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seongil-dn

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seongil-dn_mteb-eli5-with-reddit_perc

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[ { "id": "corpus-325332", "score": 0.8252949118614197, "text": "If you're into the maths, [wikipedia](_URL_0_) has a nice little article on proofs of pi's irrationality. They're beyond me, but one of the approaches taken is that certain formulas pump out answers that we know to be false if we assume that pi is *rational* (answers such as 'an integer exists that is greater than 0 but less than 1'). This method is called proof by contradiction." } ]

[ { "id": "corpus-192507", "score": 0.7838800549507141, "text": "The reason for why pi is not just a repeating decimal is well above 5 year olds, it's a proper ask science question. However, the just of it is that for a number to be rational, it must be able to be written as a/b where neither can be 0. If that fraction exists, the a lot a lot a lot of math breaks down. Since we have seen our current math be correct, then pi must be irrational.", "topk_rank": 0 }, { "id": "corpus-324330", "score": 0.7826492190361023, "text": "It's not hard to prove using a bit of geometry and some calculus that pi is what's called an \"irrational\" number—that is, a number that **cannot** be represented as a fraction of two integers. Another famous example of such a number is the square root of 2. Now think about how decimals work. (We'll stick in base 10 for now, but this works for any base). * First you write an integer, say 3. * Then you put a digit after the decimal point in the tenths place, to make something like 3.1, which represents the number 31/10. * Then you add another digit in the hundredths place, to make something like 3.14, which represents the number 314/100. * And so on. Once you put a digit in the nth place, you're representing your number as a fraction with denominator 10^n ; but pi **cannot be represented as a fraction of integers**, so no finite decimal expansion is the actual value of pi. Therefore, you need infinitely many digits.", "topk_rank": 1 }, { "id": "corpus-298579", "score": 0.7823073863983154, "text": "Well it never will be, because it can't be. [It's been proven that pi is both irrational, and also transcendental.](_URL_0_) It would be like proving 2+2=5, or that you really *can* divide by zero. Math won't ever do that, because it can't. Sorry I can't give you a better answer than that, but this is sort of like those comic book physics questions about how Captain American's shield works- it simply breaks known laws of the universe, so you could go any direction you wanted with your explanation. It's angels dancing on a pinhead.", "topk_rank": 2 }, { "id": "corpus-191747", "score": 0.7819536924362183, "text": "Here's another way to look at it. Rational numbers are ones that end with an infinite series of zeros (2.4000000...), or an infinite series of repetitions (0.1428571428571428571̅4̅2̅8̅5̅7̅.....). Now, what is the chance that any value, chosen at random, would end in an infinite pattern? Effectively zero. So you would expect that rational numbers would be the rare and unusual ones. And that is what we find. Pretty much any mathematical constant - like Pi, e, phi and the square roots of every single non-square whole number, are irrational. So Pi being irrational is nothing special. Indeed, it would be really, really strange if it wasn't.", "topk_rank": 3 }, { "id": "corpus-298939", "score": 0.7809651494026184, "text": "> Pi can be represented by 22/7 Pi can be *approximated* by 22/7. It is *not* precisely 22/7. 22/7 is exactly 3.142857..., where the ... represents that \"142857\" repeats infinitely many times. The definition of an irrational number is one that *can't* be written as a fraction. Clearly, 22/7 *can* be written as a fraction (since it is one), so 22/7 is rational. Pi, on the other hand, is not.", "topk_rank": 4 }, { "id": "corpus-252290", "score": 0.7803592681884766, "text": "Johann Lambert produced the first proof that pi is irrational. It involved many pages of manipulations of generalized continued fractions. Ivan Niven later produced a one-page proof using only basic calculus. _URL_0_", "topk_rank": 5 }, { "id": "corpus-8498", "score": 0.7789075970649719, "text": "This won't happen. [Pi has been formally proved to be irrational.](_URL_0_)", "topk_rank": 6 }, { "id": "corpus-44213", "score": 0.7785072326660156, "text": "Like you know, pi is an irrational number, so its decimal representation never repeats. It is *believed* (but not proven) that pi also has a property caled **normality**; this means that every finite sequence of numbers has probability 1 of appearing somewhere in the digits. Since any information can be represented as a finite sequence of numbers, any irrational number which is normal has this property.", "topk_rank": 7 }, { "id": "corpus-24651", "score": 0.7756004929542542, "text": "A rational number is a ratio of two integers. Pi is irrational which implies that you can’t have a circle with an integer diameter and circumference.", "topk_rank": 8 }, { "id": "corpus-83472", "score": 0.7749489545822144, "text": "We don't know. Obviously if you remove some of the first numbers of pi you get a new irrational number from pi. But we know that pi can't contain something like √2. But it could in theory contain something like e. /r/askscience has several more detailed posts about this(I guess they go a bit beyond eli5) _URL_1_ _URL_0_", "topk_rank": 9 }, { "id": "corpus-83668", "score": 0.7742769122123718, "text": "I think people are missing the point of the question. It's not \"can you write pi in such a way that it terminates,\" it's \"can pi be a rational number.\" Those are two different things. Irrationality is not defined as \"the number doesn't terminate.\" That's a property that irrational numbers have when you write numbers in an integer base, but it's not what makes a number irrational. There are plenty (an infinite number) of rational numbers that don't terminate. An irrational number is a number that cannot be expressed as a ratio of two integers (whole numbers). Writing pi in base pi makes it \"look like\" a rational number, but it doesn't have the same properties as one. It's still not a ratio of two integers: the set of integers does not change when you use a different number base.", "topk_rank": 10 }, { "id": "corpus-661272", "score": 0.7734875679016113, "text": "Was just having a discussion with a friend about that whole \"pi contains everything\" statement. Assuming that pi is suddenly proven as an infinite, non-repeating irrational number, could it still not be a normal number, is this possible?", "topk_rank": 11 }, { "id": "corpus-323435", "score": 0.772518515586853, "text": "Let's take a number that has a finite number of decimal digits. For example, 1.234567891011. You can see that it's equal to 1234567891011 / 1000000000000. In other words, it's a rational number (i.e. a fraction). So, the numbers with a finite number of decimal digits are a subset of the rationals. Thing is, irrational numbers (i.e. the numbers that are not fractions) are infinitely more numerous than the rationals. That means, if you take a number \"at random,\" without constructing it so that it's a rational, it will (very probably) be an irrational number. Both e and π have no reason to be rational (because they aren't constructed to be), so, it shouldn't be surprising that they aren't.", "topk_rank": 12 }, { "id": "corpus-317167", "score": 0.7697193622589111, "text": "2^(0.5) (the square-root of two) is irrational, and it is simply the length of the hypotenuse in a right triangle of opposite = adjacent = 1 unit. pi is also irrational, and it is simply the ratio of the circumference of a perfect circle to the diameter. Other than provide these types of examples, I'm not sure what you're getting at in your question, sorry.", "topk_rank": 13 }, { "id": "corpus-89389", "score": 0.7696965932846069, "text": "It's not just Pi; any irrational number will continue infinitely without repeating or ending. Most familiar numbers are rational numbers which means that you can divide one whole number by another whole number to get that number. So a number like 3 could be written 3/1 and a number like .25 can be 1/4. Irrational numbers are numbers for which there are no whole numbers that divide out to equal that number. We know that irrational numbers never end or repeat because if they did end or repeat, we could easily find two whole numbers that divide out into that number. We've also managed to prove that pi is irrational, but the proof is rather complex. edit: adjusted wording", "topk_rank": 14 }, { "id": "corpus-54409", "score": 0.7686818242073059, "text": "Pi exists because circles exist. Draw a circle of whichever size, measure its circumference, and then divide that value with the length of its diameter. The value so obtained is always a constant (as long as the measurements are accurate) and is called pi. Pi is not infinite, because, as said above the ratio of any circle's circumference to its diameter is what is obtained as pi, and is a universal constant. However, coming to the value of pi, it is true that pi has an infinite number of decimal places. We say that it is an irrational number. For calculation purposes, we use an approximate value of pi, that is 3.14 or 22/7. Check out videos of vihart on YouTube on the same.", "topk_rank": 15 }, { "id": "corpus-2061856", "score": 0.7685466408729553, "text": "I've seen proofs that √2 and other square roots are irrational; but its there a generalized way in which you can take a given number and know if it's irrational? Also, if you add two irrational numbers, is the result irrational? What if you multiply, or do any operation, do they behave in a predictable manner?", "topk_rank": 16 }, { "id": "corpus-121621", "score": 0.7680081129074097, "text": "Pi's not infinite. It's a finite number, it's just an irrational number. That means it's not a *rational* number - it cannot be expressed as a *ratio* of one integer to another. Among other consequences, this means that the digits of pi - when expressed as a decimal - never terminate and never repeat. As for what it is, it's simply the ratio of the circumference of a circle to its diameter", "topk_rank": 17 }, { "id": "corpus-302855", "score": 0.7662980556488037, "text": "No. Pi has been proven to be irrational. If it eventually repeats, then pi would be a rational number.", "topk_rank": 18 }, { "id": "corpus-324896", "score": 0.7660356163978577, "text": "> Also I don't know a whole lot about the non-repeating element of pi, and how that plays into the whole question. How can we even tell it will never repeat? We know it will never repeat because we know that it is irrational. The proof that it is irrational is rather involved and involves a little bit of higher level math, but it is possible to show that there are no integers a and b such that pi=a/b. The fact that it will never repeat follows from this. Note that all of this is irrespective of your choice of representation; integers are integers are integers, in any base.", "topk_rank": 19 } ]

[ { "id": "corpus-325333", "score": 0.7488545775413513, "text": "Expiration dates are almost always estimates that are added starting from date of production. A lot of foods can last longer than expiration dates and some things can even last indefinitely past expiration dates, but have them (\"best by\") to ensure quality. Like for example a lot of baking products like flour can last indefinitely as long as it's kept in an air tight container and is checked before use for things like bugs." } ]

[ { "id": "corpus-551375", "score": 0.711054265499115, "text": "There is an expiration date listed on most foods. Ignore this date and your food can last forever. You're welcome.", "topk_rank": 0 }, { "id": "corpus-372", "score": 0.7105217576026917, "text": "You are looking at date Filled vs date expired. Not date manufactured vs date expired. These drugs are created in large quantities but that doesnt mean they all get distributed at the same time. So the ones you got in 2013 and the ones you got in 2015 could have all been made in 2013. Drugs do expire.", "topk_rank": 1 }, { "id": "corpus-164831", "score": 0.7101567983627319, "text": "The FDA requires an expiration date on all food products. Canned goods once had no expiration dates, even though some could last indefinitely without spoiling.", "topk_rank": 2 }, { "id": "corpus-311279", "score": 0.7100412845611572, "text": "Expiration dates are somewhat arbitrary. The dates on packaging is not regulated or tested. Too many variables affect a food's actual quality to just go by the printed date. A good source on how long [a food lasts](_URL_0_) and, for extremely durable food, look at the [MRE shelf life](_URL_1_)", "topk_rank": 3 }, { "id": "corpus-1898568", "score": 0.7100345492362976, "text": "Imagine a fatalistic universe wherein the date and time of your death is set, but a mystery to you. By selling years off the backend, you draw that date closer, still not knowing exactly when it will be. Do you sell any years?", "topk_rank": 4 }, { "id": "corpus-353", "score": 0.7100083231925964, "text": "It is calculated by measuring the rates of breakdown under less than ideal storage conditions. With ice cream, the limiting factor is likely to be the time it takes for ice crystals to grow, as well as the oxidation of some fats, degrading the taste and texture of the product. Because of this, it is likely to be called a 'Best Before' than an 'Expiry' date. All of this is very complex, but is reduced to a certain number of days, from which is subtracted a safety margin, again carefully calculated. This is added to the date of production to give an expiry date. If it has been in your properly functioning freezer, and is a few days over, then chow down and enjoy.", "topk_rank": 5 }, { "id": "corpus-35233", "score": 0.709312379360199, "text": "From years and years of experience in industrial food processing. They know how the specific food, cooking method, preservatives and packing will effect the ability of a food to remain edible and for about how long. Food science is a serious business. As an industry, it has worked hard to make foods last as long as possible with as little additives as necessary. Those dates you see on food are the results of those years of experiments and research. Even then, they aren't always 100% accurate in that some foods last longer or less, depending on consumer storage habits. At the end of the day, it comes down to years of research and development in food science.", "topk_rank": 6 }, { "id": "corpus-31956", "score": 0.7089654207229614, "text": "Got this from _URL_0_: There are several reasons why water bottles come with an expiration date. The main one is government bureaucracy: water is a consumable food product, and as such, it is subject to laws requiring expiration dates on all consumables, from bologna to lemonade. Besides that, the expiration date on bottled water has certain benefits for the manufacturer. Although water, in and of itself, does not go bad, the plastic bottle it is contained in does \"expire,\" and will eventually start leaching chemicals into the water. This won't necessarily render the water toxic, but it might make it taste somewhat less than \"mountain spring fresh.\" If consumers contact drink companies to complain that water they bought several years earlier tastes bad, the bottlers can point out that it's their own fault for not drinking it by the expiration date.", "topk_rank": 7 }, { "id": "corpus-135727", "score": 0.7089300751686096, "text": "They aren't accurate. The date is completely dependent on the date of manufacture. If the milk is produced/bottled on Feb. 3. And the FDA says it is only good for 2 weeks, the exp date will be marked Feb 17. It is often way off. And it just took me way too long to figure out that math.", "topk_rank": 8 }, { "id": "corpus-123271", "score": 0.7074293494224548, "text": "They expiration date is not always related to the contents of the package. In this case it could be related to the bottle or the labeling on the bottle. I work in implantable medical devices, the shelf life that we label our devices with is based on the capability of the packaging to maintain sterility of the contents. It is not based on the actual device within the packaging.", "topk_rank": 9 }, { "id": "corpus-59077", "score": 0.7066317200660706, "text": "An expiration date doesn't actually tell you when the object's effectiveness starts to degrade, it tells you how long the manufacturer promises that the effectiveness hasn't degraded. (This is similar to your car dealership giving you a 50,000 mile warranty, but the car will still work just as well at 50,001 as it did at 49,999.) That being said, if the poison is one you bought, such as an ant or rat poison, after the expiration date, it would theoretically become *less* poisonous over time, as the expiration date is the manufacturer's statement on how long the active ingredient (the poison) has before it degrades.", "topk_rank": 10 }, { "id": "corpus-55686", "score": 0.7056712508201599, "text": "There tends to be 2 forms of expiration date: * Use by dates - where the product is not considered safe for consumption after that date (e.g. milk that will have gone off). * Best before / expiration dates - dates on products that don't really spoil / won't got 'off' but nonetheless will no longer be at their peak after that point. Appreciate will be slightly different in the USA but that's the basic policy in the UK - as laid out by the [Food Standards Agency](_URL_0_)", "topk_rank": 11 }, { "id": "corpus-317105", "score": 0.7047460079193115, "text": "the expiration date realistically means the safety features are at the beginning of the end of their expected life cycle. these dates are set heavily in favor of \"replace it before it's an issue\" because pressure vessel failure can easily kill someone.", "topk_rank": 12 }, { "id": "corpus-483404", "score": 0.7037963271141052, "text": "Water bottles have an expiration date because the bottle will leak nontoxic chemicals into the water that makes it taste funny.", "topk_rank": 13 }, { "id": "corpus-147756", "score": 0.7031914591789246, "text": "Over here in Germany the expiration date does not necessarily tell you about the safety of the food but also about taste, form and feeling when you chew the food (\"haptics\"?). So it's an estimate to guarantee the \"freshness\" and not necessarily if it's safe to consume.", "topk_rank": 14 }, { "id": "corpus-8777", "score": 0.7031715512275696, "text": "Rubber oxidized and can become more brittle, and the lubricant can slowly evaporate over time, both of these lead to a higher rate of failure which is generally considered bad. The expiration date is just a date before which the manufacturers are confidant that their product will perform as advertised. After it becomes statistically more likely to not (and that's a legal liability for them).", "topk_rank": 15 }, { "id": "corpus-40852", "score": 0.7023736238479614, "text": "In general the \"shelf life\" is the period during which a producer is confident that, provided proper handling, the product will perform to the standard they expect. This doesn't mean that something like bottled water will instantly spoil beyond that date or shampoo will suddenly melt your head off. It just means that the guarantee has expired and it might begin to degrade in performance. The shampoo might start to settle or separate, or more likely the manufacturer just doesn't want to be taking returns from any longer ago than that. Consider the liability issues. If a company thinks that maybe 0.5% of their products can deserve a return, they really don't want to worry about products sold *forever*. Just putting a reasonable time period on it makes sense.", "topk_rank": 16 }, { "id": "corpus-81477", "score": 0.7018328309059143, "text": "Patents last 20 years. Unfortunately, companies do the (arguably) unethical thing of tweaking their invention slightly, making it technically a new, novel invention but still similar enough to carry out the same work as the original invention. They can then patent this new invention and have another 20 years of protection. This act is referred to as \"[evergreening](_URL_0_)\"", "topk_rank": 17 }, { "id": "corpus-83479", "score": 0.7014056444168091, "text": "Cost based on expiration dates, ketchup last way longer than sour cream so they have to counteract their losses on expired product", "topk_rank": 18 }, { "id": "corpus-3075", "score": 0.6997080445289612, "text": "Employer must sell this item by : dd/mm/yy ; This item is best consumed if by : dd/mm/yy ; Consumer should finish (use) this item by : dd/mm/yy", "topk_rank": 19 } ]

[ { "id": "corpus-325334", "score": 0.7116636633872986, "text": "IIRC Americans had fewer epidemic diseases mostly due to lower population density and fewer domesticated animals. This is one of several discrepancies between the societies covered in Guns, Germs, and Steel if you want to read more. Edit: Moustachoid_T-Rex has pointed out the effects of trade and the total population of the Eurasian continent. As I have heard it explained, the combination of these factors with population density are required for epidemic diseases since they need to be able to spread quickly from person to person and have a large enough population to access that there are always fresh victims (by the time they \"return\" to an original village they have sufficiently mutated, or the population is sufficiently removed from the selective pressure that the disease can spread again). I think this may be a distinct argument from T-Rex's, so you can read his post for his explanation. To be professional, I should also make clear that this is not my field, and I claim no personal expertise." } ]

[ { "id": "corpus-161035", "score": 0.6749982833862305, "text": "> I realize that part of the answer is that: once Europe became powerful, they began to colonize and conquer native peoples thus stopping native peoples (North/South America to Africa, China, India) from undergoing industrialization. That isn't really accurate. If anything, Europeans introduced new technology to developing nations, speeding up their process of industrialisation.", "topk_rank": 0 }, { "id": "corpus-166575", "score": 0.6747648119926453, "text": "They *were* enslaved. Then, in the early 1700s, the Indian Wars caused a lot of problems for slavers, who were regularly raided by Native Americans during the wars. Gradually, most Native American tribes joined up with one of the big tribes for protection (Creek, Cherokee, etc). So it's mostly a matter of Native Americans having power centers to fall back on for protection, whereas imported African slaves did not.", "topk_rank": 1 }, { "id": "corpus-210590", "score": 0.6744834184646606, "text": "This got me thinking so I hope it's cool to add to your question OP :) I heard the Iberian, Belgian and British were brutal towards the natives but how were the French/Dutch in comparison and was the colonization of America more brutal than that of Asia/Africa/Australia?", "topk_rank": 2 }, { "id": "corpus-72455", "score": 0.6737334132194519, "text": "Both in the US and in Mexico there was an enormous massacre of natives, but it was much more widespread in the US. After the massacre, in the US it was less likely for the invaders to mate with the natives. In Mexico, there where a lot more native survivors, and after a lot of boning, they had a lot of mixed-race offspring. Also, Spaniards have slightly darker skin to begin with than Irish, British, Scottish, and other Saxon immigrants the US got.", "topk_rank": 3 }, { "id": "corpus-137136", "score": 0.6734931468963623, "text": "America was discovered that way some 10-20 thousand years before Europeans found it. That is how the natives got there.", "topk_rank": 4 }, { "id": "corpus-284153", "score": 0.6722323298454285, "text": "The evidence is strong that humans caused the decline of megafauna. These species had already endured many glacial-interglacial cycles, but in each case the arrival of humans preceeds the extinction of nearly all large mammals. Importantly, humans arrived in Australia, Madagascar, and the Americas at different times, and in each case megafauna went extinct soon after. Recall also that a glacier covered a large fraction of North America, so the land area at the time was not remotely as large as today. The large predators are thought to have gone extinct in the absence of their prey. What has not been explained is why the megafauna persisted in Africa and tropical Asia, but I think it's fairly obvious that humans were never able to reach high levels of abundance in these regions because of the high pathogen load. Humans and their pathogens evolved in Africa. These pathogens can act like a predator maintaining human populations at low density.", "topk_rank": 5 }, { "id": "corpus-628164", "score": 0.6716940999031067, "text": "I've read that Horses once existed in North America, but went extinct, which is why when Europeans reintroduced them, Some Native American tribes were aware of them.\n\nIs this true?", "topk_rank": 6 }, { "id": "corpus-134862", "score": 0.6713739037513733, "text": "It's not the water that will kill you, it's the shit in the water. No seriously the shit in the water. Cholera was the leading cause of death on the Oregon Trail, dysentery was up there as well. The answer is, it did make them sick. Edit: another thing to think about is that some naturally occurring waterborne parasites that can make you sick (giardia for instance) can take almost a month before symptoms manifest. They might not even have known what was causing the illness at that point.", "topk_rank": 7 }, { "id": "corpus-204505", "score": 0.6709344983100891, "text": "\"Native Americans\" encompass two continents and thousands of years of history. You might want to clarify what you mean.", "topk_rank": 8 }, { "id": "corpus-100829", "score": 0.6708866357803345, "text": "Its a really long answer - if you'd like to really understand it, I would recommend reading _Gun, Germs and Steel_ by Jared Diamond; it addresses this _exact_ question. At a high level, Europeans had better/easier access to high calorie food stuffs and animals fit for domestication, which allowed them to more easily form large and complex communities. This allowed for people to start specializing in their labors and knowledge, which led to further advancements of civilization and technology. When they reached the point of being able to explore the world, they were able to conqour less developed civilizations (like those in sub-Saharan Africa) and colonize them. Colonization is, as a general rule, not great for the economic health of the colony.", "topk_rank": 9 }, { "id": "corpus-235445", "score": 0.6702637672424316, "text": "Brief answer: 1. North Africa was occupied by the Romans, and even some Germanic tribes temporarily 2. Sailing techniques were not advanced enough to sail very far down the coast until the 15th century, and travelling by land would be problematic 3. Until at the earliest the 15th century, powerful states had not developed, Kings were struggling to keep their own lands let alone control others. 4. Building off of 3, these would not be simple conquests they were fairly populated regions and would have been difficult to launch effective military campaigns. 5. Unlike in North America until much later the Europeans did not have a substantial technology advantage 6. Unlike North America the local inhabitants were not wiped out by disease (upwards of 80% may have died shortly after first contact with Europeans) Basically, it was a lot harder than NA, and was not really colonized until the 19th century (except for small trading posts mainly based on the slave trade).", "topk_rank": 10 }, { "id": "corpus-273917", "score": 0.6702355742454529, "text": "Well, there was [that time the Vikings tried to colonize Canada](_URL_1_). That's an interesting bit of history more people should know about. The settlement in Vinland didn't last long but yes, there really were Europeans here before Columbus. However, we know that nobody successfully introduced smallpox or anything else obviously European before Columbus got there which puts this bound on how much contact there could have been. Archaeologists don't find every last item either. Things break down with time (or get used until they're completely broken or lost in a swamp) and there's a lot of continent to search for a population of artifacts that just can't be that high. If you want *stories* about people finding stuff like this then you won't be disappointed. Some of them are [fascinating](_URL_2_) but they are [pretty obviously mostly hoaxes, wishful thinking and false positives](_URL_0_) once you examine them for more than a moment.", "topk_rank": 11 }, { "id": "corpus-40286", "score": 0.6701991558074951, "text": "They died. The black plague wiped out something like a third of Europe. Even 100 years ago, the Spanish flu killed more people than combat did in World War One", "topk_rank": 12 }, { "id": "corpus-626552", "score": 0.669749915599823, "text": "I know the europeans provided the natives with small poxs and what not but did the natives give anything in return?", "topk_rank": 13 }, { "id": "corpus-220707", "score": 0.6692435145378113, "text": "Extremely broad question question unless we can narrow it down to a geographic area and a specific time period. One common misconception most people have about Native Americans is this \"living in harmony with the environment\" idea. While some tribes did better than others, they were still all human beings. They would overhunt, overfish and burn down the forest to flush animals out. The natural environment of North America had been drastically altered by native peoples at the time of European arrival.", "topk_rank": 14 }, { "id": "corpus-210116", "score": 0.6688385009765625, "text": "You mean specifically explorers? Probably any of the explorers that were on land and travelling had to be very careful about how they interacted with the Indians. Without a fort or some defensive works, they were outnumbered and on the natives home turf, so I suspect they treated the native very well. But once the land speculators came in and their were forts for protection, anything could happen. Check out Lewis and Clarks exploration of the north west. I believe Sacajawea was instrumental in helping communicate with several tribes that Lewis and Clark were friendly. He wasn't an explorer, but William Penn and the Quakers were very respectful of the Indians. I believe I read somewhere in England in the late 1700s when the anti-slavery groups were forming there was also one for the 'protection of indigenous peoples' or something, but I couldn't find anything with google. I believe the Spanish missions were trying to convert Indians but also protected them from Spanish settlers.", "topk_rank": 15 }, { "id": "corpus-182011", "score": 0.6684296727180481, "text": "Population density in Europe coupled with domestic farm animals created plague diseases that spread throughout the new world population. The new world population was widely spread discouraging deadly diseases.", "topk_rank": 16 }, { "id": "corpus-32483", "score": 0.6679189205169678, "text": "There has been trade between Europe and Africa, directly or indirectly, for thousands of years. Africa, Europe, and Asia are all connected by land or very short ocean distances. Diseases had already been shared between Europe and Africa long before Europeans began colonizing Africa. Africa was not 'discovered' in the same way that America is said to have been discovered. Heads of state and scholars in Africa knew about Europe a long, long time ago.", "topk_rank": 17 }, { "id": "corpus-208298", "score": 0.6678898930549622, "text": "North American Indians were enslaved for centuries by Europeans and later European-Americans. In some instances they were forced to worked in mines. For example, two American ranchers and miners, Charles Stone and Andrew Kelsey, enslaved over a hundred Clear Lake Pomo in the 1840s. They forced the Pomo to work on the ranch, perform sexual acts, and work in the mines. About 100–150 enslaved Pomo were sent to work in Stone and Kelsey's gold mine and all but two died of disease and/or malnutrition ([Lawrence and Lawrence 100](_URL_0_), [Welch 38](_URL_1_)).", "topk_rank": 18 }, { "id": "corpus-262742", "score": 0.6669402718544006, "text": "Well, Native Americans metabolize alcohol differently than Europeans do. It makes alcohol much more potent and thus addictive and deadly. (Don't read this as Native Americans are more likely to be alcoholics.) It's due to a missing liver enzyme.", "topk_rank": 19 } ]

[ { "id": "corpus-325335", "score": 0.8127520680427551, "text": "The radiation is non ionizing so there aren't any proven risks. Regulatory agencies still put limits *just in case*, but cellphones and microwaves don't even come near them." } ]

[ { "id": "corpus-29419", "score": 0.7699989676475525, "text": "I'm an electrical engineer. Cell phone radiation is in on a wavelength far longer than even infrared light, way longer than visible light. Those waves are generally very low energy. The only thing that this kind of radiation can do is 'heat you up' - think a microwave, or an IR lamp. Your phone has extremely low sending power - even at full blast, it will - for WiFi, which is essentially the same frequency as microwaves use (in the EU) hit 100mW (that's 0.1 Watts) maximum - maybe slightly more in America. Compare that to a microwave - they usually blast out 700-1200 Watts, that's a factor of 7000-12000. Worst case your phone will make your leg very slightly warm. The radiation that does give you cancer is ionizing radiation - that kind of radiation starts at the higher end of ultraviolet light, moving further to x-rays, gamma rays and all that. Electronic communications equipment doesn't use that kind of frequency.", "topk_rank": 0 }, { "id": "corpus-65074", "score": 0.7675913572311401, "text": "Cell phone towers emit non-ionizing radiation. This type of radiation is also emitted by televisions, cell phones, microwaves, fish, your mother, and dirt. If one receives a significant enough dosage, the health risk is \"getting a burn\" as this form of radiation, when absorbed, generates heat. Recommend to your mother that she not climb the tower in order to get close enough to be burned and she should be fine.", "topk_rank": 1 }, { "id": "corpus-108079", "score": 0.7665194869041443, "text": "The radiation our WiFi hotspots and cell phones emit isn't strong enough to damage cells, so in theory it should be safe. But also, billions of people have been subjected to those signals daily for decades and no increases in any diseases have occurred. It's pretty impossible to prove that they can't be harmful in any way, but it's pretty clear that if it was something really harmful or life-threatening, we would have already seen it. I wouldn't worry.", "topk_rank": 2 }, { "id": "corpus-268699", "score": 0.765106201171875, "text": "No, there's not even a theoretical basis for the idea that microwaves or radio waves can harm you, and no experimental evidence either. Of course, theoretically a strong microwave generator pointed at you instead of confined to a box could cook you in the same way it cooks food, but there's no insidious cancer or anything.", "topk_rank": 3 }, { "id": "corpus-542628", "score": 0.7647113800048828, "text": "Over the years I met several big antenna operators (mostly TV broadcast repeaters and mobile networks combined) that told me how they don't like to be near them longer than necessary due to enormous power, frequent headaches, dizziness and possibly carcinogenic properties.\n\nNow, what I read on reputable sources, RF as non-ionising radiation should be safe, always. Yet, not only people that operate those big antennas are very cautious, but on the internet as well, here and there I can find how both mobiles and wifi's are still young technologies to be thoroughly evaluated and examined and how brain tumors can be linked to long RF exposures.", "topk_rank": 4 }, { "id": "corpus-308340", "score": 0.7631757855415344, "text": "If by \"radiation\" you mean ionizing radiation, the \"nuclear\" kind that causes cancer, radiation sickness, etc, then microwave ovens, incandescent, fluorescent, and LED light bulbs all give off the same amount, namely **zero**.^* None of these devices give off harmful radioactivity to any significant degree. If by \"radiation\" you mean \"traveling energy of any kind\", then a microwave gives off about 1000 watts of energy, 10-100 times more than the light bulbs -- that's how it heats your food. Almost none of that leaks out of the cooking chamber though, and it could only harm you by heating *you* up, and for that to happen you'd basically have to run it with the door wide open. **Microwave ovens are safe.** (*) This footnote is here because some \"well technically\" wiseguy is going to talk about the short wavelength tail of the blackbody curve, or the radioisotopes in the sheet metal, if I don't.", "topk_rank": 5 }, { "id": "corpus-19231", "score": 0.7621902227401733, "text": "We mean a few different things when we say radiation - the one that springs to mind for many people is radioactivity, and that's the one that makes people go \"Aaaargh! Radiation!\" whenever it's mentioned. Radioactivity can hang around at dangerous levels for thousands of years. Microwaves use a different sort of radiation, called electromagnetic radiation. Electromagnetic radiation doesn't hang around - when the microwave pings, the radiation stops right there.", "topk_rank": 6 }, { "id": "corpus-276717", "score": 0.7606436014175415, "text": "Can you please clarify what you mean by radiation? This can range anywhere from \"can uranium from a nuclear power plant ignite a gas?\" To \" can flammable gas vapors be ignited from my microwave's radiated energy?\"", "topk_rank": 7 }, { "id": "corpus-276918", "score": 0.7595966458320618, "text": "Cell phones operate in the microwave EM band, around 2GHz. While photons in this energy range are not ionizing, they can cause damage to the human body via heating. Different tissues absorb these frequencies different amounts, and the exact mechanisms that could cause long term damage are not well understood. At the moment there is no strong causal link between exposure to low energy EM fields an long term health consequences in humans, but there are some animal studies. Sources: [mice in microwaves 1](_URL_0_) [mice in microwaves 2](_URL_2_) [mice in microwaves 3](_URL_1_)", "topk_rank": 8 }, { "id": "corpus-303418", "score": 0.7584270238876343, "text": "All of the credible evidence so far indicates that cell phone use is not harmful to humans. However, there are some political organizations (like the UN) who are taking a cautious approach and calling for more research just to make sure. Cell phones communicate to cell towers using ordinary radio waves, like the kind that are constantly raining down on you from distant galaxies. Low-power radio waves are not harmful to humans. In general, radio waves do not have enough energy per photon to cause cancer via ionization. UPDATE: The OP specifically asked about \"electromagnetic fields\". Obviously, cell phone use can distract you while driving and cause harm that way.", "topk_rank": 9 }, { "id": "corpus-286664", "score": 0.7556073665618896, "text": "> My whole point is that we use cell phones, microwaves, TVs, ~~fly in planes~~, etc., all of which produces a small amount of radiation. Why does it seem like no one is worried about that? That is all non-ionising radiation. While they do all impart energy on you they are not ionising like UV, x-ray and gamma radiation are. Ionising radiation creates free radicals that can lead to DNA damage and therefore tumors/cancer or in extreme cases radiation poisoning. People do worry about the examples you quoted but the known risk associated with them is much much lower than that of exposure to ionising radiation which is strictly regulated in its use. edit: does not apply to flying in a plane, see atomicbreweries reply", "topk_rank": 10 }, { "id": "corpus-32414", "score": 0.7549182772636414, "text": "The whole \"radio waves can harm you,\" thing is not an accepted health risk in the general medical community. Those who do say it are generally conspiracy theorists and/or people who don't understand the basis of how cell phones actually work.", "topk_rank": 11 }, { "id": "corpus-308240", "score": 0.7535920739173889, "text": "On the contrary, cell phones don't emit ionizing radiation, which is the kind that causes genetic damage. This is a blog post, but it's based on the findings of an international project called INTERPHONE, so consider this to be a layman's description of a peer-reviewed paper: _URL_0_", "topk_rank": 12 }, { "id": "corpus-191409", "score": 0.7532055974006653, "text": "Even though microwaves are low energy waves, there's still always a chance of radiation damage from any kind. If enough of the waves hit an electron in your dna then it can ionize. Non ionizing just means that one wave will not cause ionization in your body. It's all chance based, and since there's a ton of waves from any radiation, anything can happen even though the chance is really slim. Did you also know that sunlight is a form of radiation ? Flight attendants and people who fly more often then the general public actually have more exposure than people who work at nuclear facilities. Source: I work at a reactor.", "topk_rank": 13 }, { "id": "corpus-272864", "score": 0.7531151175498962, "text": "Everything emits small amounts of electromagnetic radiation, including you. There is nothing dangerous about \"electromagnetic radiation\" -- as you correctly point out, visible light is electromagnetic radiation, as is the feeling of warmth from a fireplace (infrared electromagnetic radiation). Your electrical outlets also emit a small amount of electromagnetic radiation, similar to the radio waves that are everywhere that your radio picks up. The \"electromagnetic radiation detector\" is basically just a fancy radio. And just as when you go through a tunnel or parking garage and it affects your radio signal, so does putting things near an outlet affect the electromagnetic radiation emitted by it. There is nothing special about crystals -- putting anything near it will affect it.", "topk_rank": 14 }, { "id": "corpus-7274", "score": 0.7517238855361938, "text": "Short Version: It's not Long Version: It's nooooooooooooooooooooooooooooooot. ELI5 Version: Your cellphone isn't harmful in the same way the skin doesn't melt off your face every time you microwave a burrito. The radiation isn't strong enough to be harmful. Your average ejaculate contains MILLIONS of sperm cells. Even if the radiation kills a couple, it won't make any difference. In a similar way, you are technically being burned to death every time you step outside by the suns radiation - It's just not strong enough to be noticeable or cause any damage for the most part.", "topk_rank": 15 }, { "id": "corpus-1725484", "score": 0.7482509016990662, "text": "My aunt doesn't have a microwave oven because she read that it's very dangerous to use one and what so not.\n\n\n\nShe is also disconnecting her wifi router at night because she thinks the radiaton is too high and I can't do my work online.\n\n\n\nDoes she have real reasons to be afraid or the risks are minimal?", "topk_rank": 16 }, { "id": "corpus-185932", "score": 0.7479247450828552, "text": "Radiation is basically all forms of light and a lot of forms of energy. & #x200B; The light bulb in your room and the screen you are looking at produce radiation in the form of visible light. Your microwave produces microwave radiation. Your toaster produces IR radiation. Your phone produces radiowave radiation. & #x200B; Ionizing radiation is a type of energy that can cause atoms to become ionized. Meaning there is enough power in the radiation and it is the right sized wave that it can hit an atom and cause the electrons to change states. Why this is dangerous is because if it hits the atoms that make up your DNA, it can cause your DNA to change which can lead to cancer.", "topk_rank": 17 }, { "id": "corpus-311797", "score": 0.7446205615997314, "text": "As /u/rupert1920 said, microwaves dissipates very quickly, as quickly as visible light. By the time the \"pling\" or \"beep\" indicating that the microwave oven is done reaches your ears, the energy in the microwaves will have dissipated. If you by radiation mean \"nasty radioactive stuff\", the answer is simply \"none\". A microwave oven use radio waves of the same frequency that WiFi uses, 2.5 GHz. This frequency is far from energetic enough to be ionizing, neither does it contain free neutrons. So there is nothing nuclear going on in a microwave oven.", "topk_rank": 18 }, { "id": "corpus-303509", "score": 0.7438884377479553, "text": "I tried digging around. The answer appears to either be no, inconclusive or conflicting. Now I'm confused, too! Here's one short paper from [John Hopkins University on cell phones](_URL_6_) (pdf file) WHO says [EM fields possibly carcinogenic](_URL_7_). Says inadequate to draw conclusion. Here's one on [non-specific symptoms and tinnitus](_URL_5_). No risk. Here's one on [extremely low frequency EM fields and leukaemia in childeren](_URL_0_). No risk. [Children and phones](_URL_2_). No risk. [EM study of ELF EM in adults](_URL_3_). May be a risk of meningioma especially around power lines. Interesting paper on [DNA being a fractal antenna!](_URL_1_). *DNA damage could account for increases in cancer epidemiology* [Electric and magnetic fields at power frequencies.](_URL_8_). possible carcinogenic at high levels [Childhood cancer and magnetic fields from high-voltage power lines in England and Wales: a case-control study.](_URL_4_). Not statistically significantly", "topk_rank": 19 } ]

[ { "id": "corpus-325336", "score": 0.7401657104492188, "text": "As /u/Das_Mime pointed out, we can't do it with light, but we can do it (indirectly) with gravitational waves. That's the importance of the recent BICEP2 result. If correct (it probably is), it will let us watch the inflationary epoch (about 10^(-34) sec after the BB) unfold." } ]

[ { "id": "corpus-319397", "score": 0.7029601335525513, "text": "But to us, photons definitely *do* move through time. In fact, they move at the speed of light. So no, not possible.", "topk_rank": 0 }, { "id": "corpus-833947", "score": 0.7029531002044678, "text": "I am not a scientist, but i was wondering if we could record the beginning by simply filming old light, i mean, if there was light in the beginning of the world, maybe it bounced on solid and that it could travel to us even if its old???? I am not a scientis so excuse me if it make no sense.", "topk_rank": 1 }, { "id": "corpus-290947", "score": 0.7029517292976379, "text": "You are correct. If we had a telescope strong enough we would be \"looking into the past\" of another planet. Regarding your mirror idea, if we placed the mirror 5 light years away, flying at the speed of light we would be able to put the mirror up in 5 years, and have to wait another 5 years for the light to reach us again. We could only see 10 years back, as far back as the shuttle leaving to put up the mirror.", "topk_rank": 2 }, { "id": "corpus-314140", "score": 0.7028231620788574, "text": "Absolutely, gravitational waves will do it. The BICEP2 announcement that ended up being refuted was about observations of \"primordial\" gravitational waves from the epoch of inflation, right after the Big Bang. You can obtain information from across the gravitaitonal wave spectrum (see [Lasky et al. 2016](_URL_1_). Pulsar timing arrays, which are mentioned there, are sensitive to the primordial gravitational wave background, with the latest NANOGrav results (see section 5.3 of [Arzoumanian et al. 2018](_URL_0_)) being the most constraining results when including uncertainties on the Solar System Barycenter, which affect the signal from primordial gravitational wave the most currently.", "topk_rank": 3 }, { "id": "corpus-322318", "score": 0.7027472853660583, "text": "> More precisely what I mean is, if our universe is only 13-14 billion years old, how has light from objects that are 40 billion light years away reached us. The objects were much, much closer when they emitted the light. Over time, the distance between us and the light and the distance between us and the object expanded. As a result, the light took 13 billion light-years to reach us, and the object got to be 40+ billion light-years away.", "topk_rank": 4 }, { "id": "corpus-833913", "score": 0.70265132188797, "text": "Maybe I am all wrong, but if the first light from the stars was emitted around 13 billions years ago, it means it has been travelling this entire time through the expanding universe while being redshiffted. This light is still reaching it since we can see it with HST and JWST in the future. My question is: will this infrared light from that age ever stop reaching us? Shouldn't we get \"younger\" light with each new second? Or does the expanding universe cancels out that effect?\nExample: We see the light from a Galaxy who is 13Gy old. The same light we see next year (or even of a second later)should be slightly younger, right?\nI know I haven't been really clear but I hope you understand what I am asking! Thanks!", "topk_rank": 5 }, { "id": "corpus-290074", "score": 0.7011412382125854, "text": "Yes ! Some of the most famous and earliest example are the [1572](_URL_0_) and [1604](_URL_1_) ones that were visible during day time. Wikipedia talks about 8 of such events. However the one visible with the naked eye are only found within our galaxy as other galaxy are to far from us. We can detect those with telescopes tho.", "topk_rank": 6 }, { "id": "corpus-262515", "score": 0.700964093208313, "text": "Light travels at the speed of light. If an object one light-year away, then the light we see from that object left the object one year ago. If the object is a million light-years away, then the light we see left the object a million years ago. This quasar is about 12.8 BILLION light-years away, which means the light we see from it left 12.8 BILLION years ago. The light we see now left the quasar only 1 billion or so years after the Big Bang, and since then those photons have been traveling through the vast emptiness of space before they arrived at our telescopes! So, to answer your question - to see light from the beginning of time, we need to look at very, very distant objects!", "topk_rank": 7 }, { "id": "corpus-302641", "score": 0.7006940841674805, "text": "In addition to what /u/petascale mentioned: Large telescopes. A 3 meter telescope can collect about a million times the light a human eye can collect. The ELT (under construction) will collect more than 150 times the light a 3 meter telescope can collect.", "topk_rank": 8 }, { "id": "corpus-251512", "score": 0.7006424069404602, "text": "The very short answer is the universe was smaller in the past, so the photons travel along a path that's ~12 billion light years long as the photon experiences it, but the distance between us and the quasar \"today\" is ~18 billion light years. The path behind the photon continues to expand after the photon goes by, so today it's longer than it was when the photon was there. I'm not sure which complications are worth knowing. Simultaneity is not a well defined idea for distant places travelling at high relative velocities [Wikipedia](_URL_0_). This is probably the biggest problem with this explanation.", "topk_rank": 9 }, { "id": "corpus-249051", "score": 0.6998857855796814, "text": "Would we ever be able to measure it? If we're looking for a gravitational wave background that's similar stylistically to the CMB, it's earliest surface would be at nucleosynthesis right? I would think that anything from that time period would be redshifted into oblivion. The start of BBN was about ~0.1s post BB and average temperature of 10 MeV, which would mean its it's corresponding temperature now would be ~1.4x10^-8 eV, or 1.7x10^-4 K if I scaled it properly (just started learned it this last school term, might not have). These were found assuming radiation domination until 47000 years post-bang, matter dom afterward, no dark matter. If we use the end of BBN as the surface (100keV) this this becomes orders of magnitude smaller.", "topk_rank": 10 }, { "id": "corpus-263561", "score": 0.6998464465141296, "text": "There basically is. At sufficiently high energies or densities you'd run into the [Schwinger limit](_URL_0_) where a noticeable fraction of the photons interact with each other. The limit's pretty high though. We're only just approaching it with our high intensity laser experiments.", "topk_rank": 11 }, { "id": "corpus-285207", "score": 0.6998387575149536, "text": "Yes, but it's very very unlikely. It's called photon-photon scattering. _URL_0_ TLDR: You need lasers with ginormous energy densities to produce a meager few events once in a while.", "topk_rank": 12 }, { "id": "corpus-305049", "score": 0.6995907425880432, "text": "Technically yes. However, obviously an object can intersect between the viewer and the light source cutting off that particular source of photons for some time. So, for example, if you are observing light from 1 million light years away, and an object intersects at 500,000 light years, you won't see the light disappear for 500,000 years. That doesn't mean that photons are still not there, from other light sources - but simply not from the one that was blocked. Another possibility to think of is the object emitting the light is no longer there. In that case you will still receive photons up to the point where the object stopped creating them (delayed, of course, by the distance to the object). So... if a star 1 million light years away burns out today, you will still see photons for 1 million years - even though the star no longer exists.", "topk_rank": 13 }, { "id": "corpus-169189", "score": 0.6993255615234375, "text": "No, the observable universe is like 97 Billion light years across, within it are trillions of galaxies. Things could be outside that, but light from it would not have had time to reach us.", "topk_rank": 14 }, { "id": "corpus-168354", "score": 0.6992666721343994, "text": "The big bang didn't occur at a single location. It was the condition of the entire universe at the time. So there is light reaching us today, that was emitted at time close to the big bang, from all directions. This is simply because in all directions, there is a point from which light has been traveling for that amount of time. With regards to the galaxy you are asking about, yes, it was 13 billion light years away from us (approximately) at the time the light we are seeing now was emitted. That does not take into account expansion, which would mean it was actually closer. It is much further away from us today because during the entire time the 'distance' has been growing as that light was traveling. We can't look in the opposite direction and draw conclusions, because that light is gone, we can never catch it again. edit: I'd love to know why the downvote, so I can address.", "topk_rank": 15 }, { "id": "corpus-318768", "score": 0.6992143392562866, "text": "Yep, if the universe is like that, then extremely distant things could be visible mulitple times. [Researchers have looked for evidence for evidence of that](_URL_0_) in the cosmic microwave background and haven't found any, which can be used to constrain the size of the potential torus that the universe might be.", "topk_rank": 16 }, { "id": "corpus-312053", "score": 0.698722243309021, "text": "It is correct that we can only see objects for which enough time has passed for their light to reach us. However, since the universe is expanding, the furthest objects we see (whose light is 13.7 billion years old) are much further away than that, about 46 billion light years. Additionally, it is also the case that those objects we see 46 billion light years away today, were much closer when their light was emitted.", "topk_rank": 17 }, { "id": "corpus-293299", "score": 0.6987096071243286, "text": "**Short answer:** Yes. If you're near a black hole. **Longer answer:** So you already hit on the fact that light can't escape black holes, and it turns out that if you are at just the right distance from the event horizon (which is sort of the point of no return- where the black hole begins and the normal universe ends), photons can actually orbit at this point. It means that if you were at this point, and you looked straight ahead, you'd see the back of your head! Anyway, it's called the [photon sphere](_URL_0_) (not to be confused with the photosphere of the sun).", "topk_rank": 18 }, { "id": "corpus-279029", "score": 0.6985517740249634, "text": "> Extending this, is a gravitational force between photons? Yes, if they are not perfectly parallel (that also answers your last question). > And is it large enough to be observed? Not with today's technology, and not with any planned or even proposed experiment.", "topk_rank": 19 } ]

[ { "id": "corpus-325337", "score": 0.6684457659721375, "text": "Matter that is heated expands, causing its density to decrease. Due to gravity heated (less dense) matter rises above cooler matter. With flames you see that typical shape because the heated air causes convection currents that pull the flame along. It doesn't always happen this way though - flames with pressure behind them like from a gas soldering torch will keep going in the direction the gas was emitted, and flames in zero-gravity will form balls. Check out Veritasium's video with a lighter on the Vomit Comet - _URL_0_" } ]

[ { "id": "corpus-313097", "score": 0.6348124146461487, "text": "No, hot gas or liquid rises due to the fact that almost all materials decrease in density when heated and thus become more buoyant. As there is no gravity on the ISS (or, more correctly, because it is in free-fall) hot fluids will not rise. This has the effect of making [fire](_URL_0_) behave quite differently.", "topk_rank": 0 }, { "id": "corpus-169276", "score": 0.6347081065177917, "text": "common myth is that rockets go straight up. the acceleration is primarily necessary in the lateral direction to reach orbital velocity. SO at some point, you need a whole lot of acceleration sideways or your gonna come right back down.", "topk_rank": 1 }, { "id": "corpus-2789941", "score": 0.6346977353096008, "text": "I noticed this. If you take two matches and let's say they are both burning at 1cm height. If you put second match at the top of the flame of the other match. It amplifies the flame of the top match. How do you call it, where does science use this interaction?", "topk_rank": 2 }, { "id": "corpus-316452", "score": 0.6345471739768982, "text": "Buoyancy is a less dominant force on tiny particles than drag is. They pretty much follow the flow they're entrained in, and in the case of smoke that's a volume of hot air. So long as the density of hot air plus smoke is less than that of the surrounding cool air, it will rise.", "topk_rank": 3 }, { "id": "corpus-186239", "score": 0.634190022945404, "text": "The sun isn't on fire. Fire is oxidation, where fuel + oxygen + energy = reaction (fire and the fuel changes composition). & #x200B; The sun is fusing elements into new elements (for now it's Hydrogen into Helium), and when you smash elements together, they release energy in a process called Nuclear Fusion.", "topk_rank": 4 }, { "id": "corpus-25009", "score": 0.6341396570205688, "text": "There are two issues here: 1. The colour of the flames: That is related to what elements you are burning. See fireworks which can be green or red or yellow or blue, depending on the kind of metal. 2. Yellow flames of a burner is due to incomplete burning, you will end up with charred objects if you put something in the flame. Blue nearly invisible flames of a burner is complete burning, you won't get any charring on the objects in the flame.", "topk_rank": 5 }, { "id": "corpus-255810", "score": 0.6339826583862305, "text": "In your pyrotechnics example, that wave of heat that you feel is a result of radiative heat transfer. This wave rushes to you very quickly (speed of light) because it is the light (primarily infrared) that is transferring heat. Hot objects all around transfer heat this way, including our sun! You have seen things become so hot that they glow red, that's the same idea as well. Also, as flames get hotter, their color changes from red to orange to blue to white because the black body radiation spectrum is temperature dependent.", "topk_rank": 6 }, { "id": "corpus-322690", "score": 0.6336337327957153, "text": "It's not the liquid wax that burns, it's the vapors. The liquid gets drawn up the wick, and vaporized when it reaches the flame proper, and is burned then (as a general rule, most everyday things that burn do so as a gas: it's the only way to get a sufficient mixture with the oxygen it reacts with while burning).", "topk_rank": 7 }, { "id": "corpus-321479", "score": 0.6335759162902832, "text": "If you have ever seen differently fuelled \"clean\" fires with different colours, that light is the characteristic light or wavelength of that fire. This light is emitted when your highly energetic atoms and molecules fall from an excited electronic/vibrational state to a lower state, emitting light within a narrow range of specific wavelengths. The general light you're used to in more typical \"dirty\" flames is a mix of the previously mentioned source, and something known as blackbody radiation. All objects above absolute zero emit light. You can see this when you heat up metals until they glow, or when you put out a flame and glowing ashes remain, or even when you look through an infrared camera and see people glowing in the infrared region.", "topk_rank": 8 }, { "id": "corpus-36511", "score": 0.6335469484329224, "text": "TL;DR is that blue light is higher energy than red ligit. This means that the hotter something is the more energy there is so the more blue the fire appears. There are [more things than temperature](_URL_0_) that effect color, depending on what chemicals are burning. Copper burns green or blue, lithium burns red, and potassium burns purple, for example.", "topk_rank": 9 }, { "id": "corpus-81768", "score": 0.6333867311477661, "text": "Basically, on a large fire, you're introducing more oxygen. On a candle, the force of the moving air is enough to smother the flame, since, as the above reply stated, candle wicks are flame retardant.", "topk_rank": 10 }, { "id": "corpus-323594", "score": 0.6330502033233643, "text": "Fire is a chain reaction. The reaction between the carbon in the wick/wax and the oxygen in the air creates heat, that heat give other molecules enough energy to react, which creates more heat, etc. When you blow on a candle what you are doing is blowing the hot air away from the wick, and replacing it with cool air, which cools down the wick. There is now not enough energy in the area for more reactions to occur.", "topk_rank": 11 }, { "id": "corpus-178534", "score": 0.6329504251480103, "text": "It doesn’t burn like fire. It’s essentially a giant nuclear reactor. The gravity in the center is so great that it smashes hydrogen atoms into heavier elements... It’s more like a super massive nuclear bomb going off and not like a giant campfire. It’s obviously more complicated than that, but the short answer is that it’s nuclear fusion and not combustion. Good question though 😊", "topk_rank": 12 }, { "id": "corpus-296057", "score": 0.6329060196876526, "text": "The fire you see is just the effect of incandescence. When atoms are heated up to that degree they emit light, hence the visible flame. The variation in colours depends on what you're burning. The conglomeration of atoms that comprise the flames you see would be classified as a gas.", "topk_rank": 13 }, { "id": "corpus-155945", "score": 0.6327837705612183, "text": "It literally goes up in smoke. It's the fuel that allows the flame to burn, drawn up the wick, which isn't just a clever name... When it cools, it settles into soot that makes a fine layer of dust everywhere in your house. Burning enough candles will cause a noticeable increase of dust in your house.", "topk_rank": 14 }, { "id": "corpus-263986", "score": 0.6327426433563232, "text": "The same reason, more or less, that your fire doesn't burn the fireplace: the fireplace isn't made of fuel. Only a few types of heavy atom are subject to neutron-induced fission. When neutrons hit (say) concrete, the concrete doesn't emit yet more neutrons. Thermonuclear detonations (fusion bombs) are even more analogous to a very high temperature fire: they work by heating light elements very hot, and those elements fuse and release more heat that allows the reaction to continue. Most light elements can yield energy through fusion, so in principle a large enough hydrogen bomb could fuse (say) all the nitrogen in the air. But it turns out to be very hard to keep the heat from fusion concentrated enough to enable further fusion, just like a firecracker going off in a forest doesn't necessarily set all the trees on fire. Except worse, because fusion requires very high temperatures to achieve and it takes something the size of a star to keep the \"fire\" going.", "topk_rank": 15 }, { "id": "corpus-23468", "score": 0.632355809211731, "text": "Good question, lots of people know what a combustion reaction is, but not what \"fire\" is exactly. The reaction itself isn't very important to understand, all you need to know is that when something burns, it releases CO2, which is a gas. Now, imagine a forge. When the metal in a forge gets really hot, it starts to glow a redish tinge. We see this all over the place (electric stove, for example), things heat up and they glow \"red hot\". This is exactly what's happening during combustion. The CO2 gas floats upwards and is so hot that it glows. This is what we actually see as fire. As it rises and gets further from the reaction it cools and we see other colors before it returns to being transparent. Hope that helps!", "topk_rank": 16 }, { "id": "corpus-287685", "score": 0.6323397159576416, "text": "A flame is a reaction in gas molecules that is self-sustaining, and thus requires enough thermal energy to break the bonds, so there should theoretically be a low enough temperature. According to NASA, nobody knows how low this limit is, but cool flames have been made at temperatures as low as 120°C. This flame sustaining limit is being researched by NASA (microgravity flames, etc.). Oh, and such cool flames use mixtures of fuel and air. More info [here.](_URL_0_)", "topk_rank": 17 }, { "id": "corpus-163967", "score": 0.6322091817855835, "text": "Two flat sheets do not allow a significant amout of oxygen in between the two. Without this oxygen, the burn rate is slowed down, and the fire takes longer to build. It's like how you can breathe inside the ball pit at Chuck E. Cheese but you can't in a pool of water.", "topk_rank": 18 }, { "id": "corpus-313027", "score": 0.6321837902069092, "text": "I think where you're off is your assumption that the wood is \"undoubtedly higher in energy\". The blue part of a flame is pretty darn close to, if not actually, a plasma -- whereas the wood is a boring old solid. The red from the wood, as well as the white/yellow/orange/red from a flame, comes from [black body radiation](_URL_0_), i.e. glowing from being hot. The blue of the flame comes from photochemical effects from the chemistry of combustion. The wikipedia article on [flame](_URL_1_) covers this pretty well. Since the hottest part of a flame is the combusting/blue part, it makes sense that the blackbody colors would be more red as you move away. Also, keep in mind that the wood is only hot because it's near all the hot combustion in the gas phase. Smoldering embers aren't as hot as a flame for a variety of reasons, so you can expect them to be red. Everything discussed here fits pretty well into a framework of purely emissive phenomena, so there's no need to evoke absorption or reflection.", "topk_rank": 19 } ]

[ { "id": "corpus-325338", "score": 0.6769430041313171, "text": "There are primarily two forces to consider: pressure and surface tension. There is an outward force due to the difference in pressure between the inside and outside of the bubble, and there is an inward force due to surface tension. The force due to the pressure gradient is trying to increase the volume but the force of surface tension is trying to decrease the surface area. These forces reach equilibrium at the shape which minimizes the surface area for a given volume: the sphere." } ]

[ { "id": "corpus-257388", "score": 0.6430838704109192, "text": "Tiny bubbles. The candy is made by making a hot syrup of melted sugar and flavorings, and then mixing it with high-pressure carbon dioxide. As the foamy mixture cools and hardens, lots of tiny gas bubbles become trapped inside, still at high pressure. When you eat the candy and it starts to dissolve, those bubbles pop. The release of pressurized gas is what makes the rocks fizz in your mouth.", "topk_rank": 0 }, { "id": "corpus-301936", "score": 0.6430539488792419, "text": "They are spherical, and they are generally depicted as such. It's just that when you portray a spherical object in a 2D image, it looks like a circle. What can be flat is the accretion disk, the gas and plasma that's orbiting and falling into the black hole. It forms a disk because any gas not orbiting in the disk would collide with the disk and become part of it. Gas and plasma are highly collisional and will exchange angular momentum quickly until they're orbiting in a relatively smooth, circular orbit.", "topk_rank": 1 }, { "id": "corpus-171877", "score": 0.6430350542068481, "text": "The blue liquid inside the can is very thick and full of little bubbles (like a chocolate mousse, but much tinier). The bubbly liquid is packed into the can really tightly, there isn't a lot of space, so the bubbles get squished down smaller to make room. When the liquid comes back out of the can, the bubbles have lots of space again, so they're free to stretch back out to their normal size. The bubbles are colourless, so as they grow, they make the colour of the liquid look fainter and fainter.", "topk_rank": 2 }, { "id": "corpus-293933", "score": 0.6429213881492615, "text": "Your guess was right. Pyrex is very smooth. If there are no irregularities, it's possible that no bubbles form. The water just basically becomes superheated. Once it's disturbed, causing irregularity, it'll boil in a flash. When I microwave water in Pyrex, I always put a wooden skewer in there to give the bubbles a place to start forming.", "topk_rank": 3 }, { "id": "corpus-320655", "score": 0.6428579688072205, "text": "The powder acts as a nucleation trigger. Basically, the fine particles allow gas bubbles to start to form from the co2 dissolved in the beer. If you add a lot, you'll trigger a lot of bubbles, hence - what I'm guessing you saw - a massive overflow of frothy head (stop sniggering at the back).", "topk_rank": 4 }, { "id": "corpus-48326", "score": 0.642845869064331, "text": "It's because when you press on one side of a circle/sphere, the area that sees the highest pressure on the other side is where a line passing through the center of the sphere \"comes out\". So imagine you're pressing on a spherical balloon (your eye). The black spot you see is because of pressure on your retina. To figure out the location of the spot, imagine a line from the area where you're poking, through the (undeformed) center of the balloon and out the back. The location where the line comes out the back of the balloon is where the highest pressure is, and therefore where you see the black spot. This process is what causes the mirroring you observe because of the symmetry of the sphere.", "topk_rank": 5 }, { "id": "corpus-835194", "score": 0.6428366899490356, "text": "when air is released in the space does it form a bubble? will you be still able to see it?", "topk_rank": 6 }, { "id": "corpus-324657", "score": 0.6427071690559387, "text": "Those imperfections act as nucleation sites. In your example they help with the physical separation of the gas (carbon dioxide) from liquid (water). When you open the bottle some of the carbon dioxide dissolved in the water wants to leave (pressure change) and go into the air but it can't because the individual CO2 molecules cannot overcome the viscosity of the water. The nucleation site provides a place for CO2 molecules to aggregate and form bubbles capable of breaking the hydrogen bonds of the water molecules. Without the imperfections there is nowhere for the CO2 molecules to coalesce.", "topk_rank": 7 }, { "id": "corpus-165227", "score": 0.6425830721855164, "text": "Helium is lighter then air, this is what makes balloons float. Sound is created by waves traveling through air, and because the helium is lighter the waves travel faster. This results in a higher pitch. Fun fact, if you use a gas denser then air you voice will get super low. [This video from the Mythbusters explains it well and demonstrates both high and low pitches achieved with gasses. ](_URL_0_)", "topk_rank": 8 }, { "id": "corpus-288474", "score": 0.6424956917762756, "text": "> I still don't know why different-temperature blobs of wax resist combining together, Because there's a layer of water between them that they're phobic of. The hot metal coil pops them, though. > why shaking a heated lava lamp causes it to permanently become cloudy Because it creates wax bubbles so tiny that they never coalesce with the big one.", "topk_rank": 9 }, { "id": "corpus-834290", "score": 0.6424774527549744, "text": "Given a closed system containing a gas and a liquid into which it can dissolve—let's say carbon dioxide and water in a sealed bottle—at any given temperature, the system will reach a dynamic equilibrium, wherein the the overall concentration of carbon dioxide dissolved in the water at any point remains essentially the same. My understanding of the reason for this is that, at this temperature, for this quantity of gas, the quantity of gas entering solution at any given time is equal to the quantity exiting solution, so that the overall concentration remains the same.\n\nIf I now open the bottle, the gaseous carbon dioxide above the water diffuses into the atmosphere of the room I'm in, and in turn, the carbon dioxide in the water diffuses out of the water until it has reached a new equilibrium. As it diffuses out of the water, it forms visible bubbles.\n\nHowever, I don't understand why the CO2 should only form bubbles when there is a net diffusion of CO2 from the water. If my understanding is correct, before the bottle was opened, on the molecular level, dissolved carbon dioxide was always leaving the solution at a constant rate, except that an equal number of CO2 molecules were entering the solution at that same rate. Opening the bottle does not increase this rate. If the CO2 molecules leaving the solution did not form moving bubbles in the first case, why do they form bubbles in the second case?\nPlease, help me understand what I'm missing or misunderstanding.", "topk_rank": 10 }, { "id": "corpus-181865", "score": 0.6424680352210999, "text": "Flame is a result of burning air(hot air). Hot air is less dense than cold air, hence hot air rises up(like how a hot air balloon works, or if you imagine the atmosphere to be a pool of water, how a float would float upwards). Hence flame would also burn upwards. & #x200B; If free of gravitational effects, you can actually get a round spherical flame.", "topk_rank": 11 }, { "id": "corpus-88361", "score": 0.6424344182014465, "text": "Imagine a hollow sphere, made of glass, with a vacuum inside. Out in space, a vacuum, it wouldn't break under the pressure. Then imagine it in Earth's atmosphere, where it would obviously implode. But you and I aren't imploding, correct? If the internal pressure is equal to the external pressure, it won't explode or implode, regardless of the magnitude of the pressures involved.", "topk_rank": 12 }, { "id": "corpus-260570", "score": 0.6423774361610413, "text": "It creates a massive steam bubble, it doesn't last too long (not sure on actual time it is there for) but something interesting happens when the \"bubble\" is there. The gas makes the bubble expand until it reaches the maximum size it can as the pressure forcing the bubble to expand becomes weaker the water pressure causes the bubble to collapse on itself before expanding again (this can also result in a flash of light as the bubble collapses). This actually happens a few times, each time the \"bubble\" gets smaller in size until the energy is depleted. I will try to find a video explaining it as I may not have done a terribly good job of explaining it. Edit: What I am talking about happens at the three min mark of this video: _URL_0_ Edit 2: a more in depth video of the bubble side of things, _URL_1_ starts explaining it at the 6 min mark. I couldn't think of the word but the video reminded me, the bubble oscillates in the water. The size of the bubble would depend on the energy released by the explosion.", "topk_rank": 13 }, { "id": "corpus-320306", "score": 0.6423105001449585, "text": "It's a colloidal suspension. When you whisk it, you're mechanically breaking apart the preferred groupings of molecules and beating air into the mixture. Your continued stirring prevents the mixture from re-suspending, and eventually the phospholipids will reestablish membranes around air throughout most of the mixture. At that point, it can hold its shape, and remains more or less a stable froth. If you were to continue whisking, it would separate entirely and you'd end up with butter.", "topk_rank": 14 }, { "id": "corpus-87592", "score": 0.6422505974769592, "text": "Air! When you whip the cream, you're incorporating a lot of air into it. The little bubbles, combined with the cream, end up forming a foam instead of a liquid.", "topk_rank": 15 }, { "id": "corpus-80004", "score": 0.6422112584114075, "text": "I'm kinda guessing here, but I bet it happens between making the dough and cooking. They're made by extruding the dough, I bet the crunchy ones are out through a smaller nozzle and made with a chunkier dough so they simply break off. The puffy ones are rather uniform so I bet they're made with a smoother dough that gets cut off in the machine. Source: _URL_0_", "topk_rank": 16 }, { "id": "corpus-302921", "score": 0.6422009468078613, "text": "It's actually quite common to see oxygen bubbles on aquatic plant life, particularly if it's in bright sunlight. There are a couple of reasons you might not have noticed it though. First of all, this only happens with plants that are photosynthesizing quickly, in water that is already holding a lot of oxygen. Basically, most oxygen simply dissolves directly into the water, and you only get bubbles if the plants are producing oxygen faster than it's dissolving. Second, the bubbles produced are relatively small and if you aren't looking closely you probably wouldn't see them.", "topk_rank": 17 }, { "id": "corpus-261846", "score": 0.6421664953231812, "text": "They are bits of sugar with compressed CO2 bubbles in the middle. The sugar is strong enough to keep the CO2 inside it's bubble, but when you put them in your mouth you dissolve some sugar and weaken the sugar (the \"walls\" of the bubbles become thinner), eventually the bubble is weak enough that the pressure from the CO2 can break the rest of the sugar, and that happens explosively.", "topk_rank": 18 }, { "id": "corpus-37891", "score": 0.6420723795890808, "text": "Cold water can hold more dissolved gasses than warm water. As the water warms up, gas bubbles form. The bubbles form along the glass because that's where it's warmest.", "topk_rank": 19 } ]

[ { "id": "corpus-325339", "score": 0.818629264831543, "text": "Colligative properties, my friend. The mixture of a solvent (here, water) and a solute (ethanol) will make a solution that has a freezing point below the solvent alone. The more solute there is, the more the freezing point is depressed, so beer will freeze before wine which will freeze before vodka, ignoring other solutes. If you had low-proof booze and got it cold enough, the solution would freeze. But the water would freeze out first, leaving behind a solution with a higher concentration of alcohol. Ta-da! You've fortified the booze without a still! The same phenomena is why you put antifreeze + water mix in your car radiator, put salt on the roads in the winter, and use rock salt (CaCl2) instead of table salt (NaCl) mixed with ice to make ice cream." } ]

[ { "id": "corpus-292221", "score": 0.7729765772819519, "text": "Freezing only happens if you have something called nucleation points, which are places where the ice crystals can start to form, such as a seed crystal or other uneven spot. If the inside of the bottle is smooth enough, and the water pure enough, the ice crystals have no place to form, even if the temperature of the water is below 0 °C. Once you open the bottle or shake it or disturb the water in some other way, there might be some small bubble of air forming, or some other kind of small spot where the crystals can begin to form, and because the temperature is below 0 °C the crystals will keep forming. Freezing releases heat, which is probably why all the water in your bottle did not freeze.", "topk_rank": 0 }, { "id": "corpus-279600", "score": 0.7698219418525696, "text": "Sure. For example, look at the [phase diagram](_URL_0_) of a water/ethanol mixture. Notice that the freezing point of the system drops drastically with increasing ethanol concentration, such that when the fraction of ethanol is above 90%, the freezing point will be less than -100C! This explains, for instance, why Vodka doesn't freeze in household freezers. Edit: As for then removing the ethanol, that would get a bit tricky since water and ethanol will have an [azeotrope](_URL_1_) with a composition of 95% ethanol, meaning that when removing the liquid, this will be the first component removed. As you keep removing this azeotrope, the concentration of water will keep increasing, so at one point it will freeze (assuming you're keeping the system at a constant temperature), although ethanol will be trapped in the solid.", "topk_rank": 1 }, { "id": "corpus-49508", "score": 0.7623656988143921, "text": "The key here is you opening the bottle, which releases some of the carbon dioxide from the liquid. The CO2 decreases the freezing point when in the solution, but once it's released the freezing point goes up, meaning the beer can freeze.", "topk_rank": 2 }, { "id": "corpus-313506", "score": 0.759809672832489, "text": "Theory C that you listed is closest to the answer: It's essentially random which bottles freeze. If no nucleation occurs in the bottle (no disturbance, and very smooth walls) the beer can be cooled significantly without freezing, but some bottles simply have nucleation sites that cause crystallization to occur easily. It really comes down to slight movements of the bottles (vibration), and manufacturing irregularities in the glass. All the bottles have plenty of room to allow for freezing, the beer company thought of that :) a bit of source for ya! (supercooling)[_URL_0_]", "topk_rank": 3 }, { "id": "corpus-300918", "score": 0.7579458355903625, "text": "No. Alcohol and water are 100% miscible, meaning they blend together perfectly. For something to settle out of solution, you would need it to precipitate.", "topk_rank": 4 }, { "id": "corpus-147357", "score": 0.7564600110054016, "text": "If the water is very pure and is in a very clean bottle with a very smooth interior, it can become \"supercooled\" which means it's below the freezing point but remains liquid. The reason for this is that ice forms by creating crystals that start around a bit of dust, a crack or other imperfection on a surface, but if none of these exist, it cannot start the process of freezing. When the bottle is disturbed, it creates air bubbles, allowing the ice crystals to begin forming and the bottle freezes in a moment. Here's a video demonstrating the effect: _URL_0_", "topk_rank": 5 }, { "id": "corpus-283394", "score": 0.7554609179496765, "text": "Ice sculptors and upscale bars boil their water before use so it always freezes crystal clear. Heat drives off dissolved gasses so the ice is not full of thousands of tiny bubbles making it look white. But why just the center? Anything that's not water will have a hard time incorporating into the crystal structure of the ice. Water bottles also freeze from the outside. Incidentally this will concentrate more than just dissolved air including things you probably want like alcohol. Search for freeze fractional distillation and the northerner beverage known as applejack for practical applications.", "topk_rank": 6 }, { "id": "corpus-318283", "score": 0.7545377016067505, "text": "The (higher than atmospheric) pressure inside of the bottle lowered the freezing point to below 0C, so although it was below what the freezing point would be at standard pressure it stayed liquid. When the bottle was opened the temperature stayed the same but the pressure suddenly dropped, raising the freezing point above the actual temperature, and the drink froze. It happens with beer in the freezer too.", "topk_rank": 7 }, { "id": "corpus-160098", "score": 0.7523912787437439, "text": "In the brewing processes, the beer is cooled so that some of the water freezes, increasing the ABV and removing some of the soluble impurities (impurities that affect taste). Alcohol has a lower freezing point that water, so by controlling the rate and temperature, water ice crystals form which can be physically separated from the rest of the mixture - like straining out the final bits of ice in a nearly-melted slushy.", "topk_rank": 8 }, { "id": "corpus-321913", "score": 0.7508513927459717, "text": "Ice melts faster in liquor due to an effect called [freezing point depression.](_URL_0_) I've linked the Wikipedia article, but basically, the solvent lowers the freezing point of the ice, therefore, instead of water freezing at its normal 0 degrees C, it now freezes at -1 or -2 degrees C when in a EtOH + water solution (don't quote me on these numbers please! I've only giving them qualitatively). As a result, the thin layer of ice that's in contact with the liquor (what we would call the \"boundary layer\" in mass transfer) immediately melts. This is also the same reason as to why we salt roads to prevent them from freezing, or why we add ethylene glycol to prevent our engines from overheating.", "topk_rank": 9 }, { "id": "corpus-109287", "score": 0.7468317151069641, "text": "Because of something called \"latent heat\"; it's the same reason ice doesn't instantly melt when brought into an environment warmer than 32 degrees. You need to remove a certain amount of heat from the water to cool it to 32 degrees. Then, you need to remove a lot more heat, which will not reduce the temperature at all, the convert it from liquid at 32 degrees to a solid at 32 degrees. This is why ice is so much better at cooling drinks than whisky stones; the drink needs to give up a LOT of heat to melt the ice. Also, there is the question of heat transfer. For, say, a puddle to freeze, it has to transfer its heat from itself to the cooler air and/or ground. And things don't transfer heat instantly. Some highly thermally conductive arrangements, like your hand on a hot pan, transfer heat well. But air is not a super good conductor of heat; it's the same reason you can open your oven and look and reach in without burning your hand to a crisp.", "topk_rank": 10 }, { "id": "corpus-179098", "score": 0.7468006610870361, "text": "It looks like the water is supercooled. Ie it’s pure water that is below freezing temperature - when you cool water in this manner it won’t freeze until there is either an impurity for ice crystals to form around or if you shake the water (you can try this at home - buy a bottle of purified water and stick it in the freeezer for a few hours, carefully pull it out and it’ll likely still be liquid but will freeze if you shake it). When they dip the cherry in either ice crystals already on the cherry or the cherry itself provide a base for the ice crystals from the super cooled water to latch onto. The whole cup doesn’t freeze because forming ice releases heat energy into the surrounding environment (in the opposite process of how you need to add heat energy to ice to melt it), so the ice that does form warms the rest of the water to above freezing.", "topk_rank": 11 }, { "id": "corpus-292885", "score": 0.7462818622589111, "text": "There could be two different things at work, the first of which is that sugars and alcohols lower the freezing point of liquids. A typical can of soda or soft drink will have around 36 grams of sugar in it, so you can get a greatly reduced freezing point. The other is a phenomenon called [supercooling](_URL_0_) where a liquid is cooled bellow it's freezing point without actually turning into a solid, this is most common in things like pure bottled water because the ice crystals need some type of impurity to help them form. Supercooled fluids will [have a tendency to insta-freeze if you give them a shake](_URL_1_) or introduce an impurity.", "topk_rank": 12 }, { "id": "corpus-54609", "score": 0.7461932301521301, "text": "Beer is carbonated, so has CO2 in it, byproduct of yeast metabolism. In a closed container, some of that gas is going to be in a little bubble at the top, some will be dissolved into the beer. When beer, which is mostly water, freezes, water likes to have these nicely arranged little structures of molecules, crystals. So throw in something to jam up that structure, such as CO2 gas dissolved in it, and that kind of messes of the process. And here \"messes up the process\" means it has to be colder to overcome that - lowers the freezing point. So you drop the beer, shake up things a little bit, some of that CO2 dissolved in the beer comes out and joins the bubble. Same idea as shaking a can of soda then it blows up when you open it. Meaning, CO2 in the bubble, now that's not in the water any more, not disrupting the freezing process anymore, so now the freezing point nudges up a little, doesn't have to be as cold in order to freeze. Thus, this bottle freezes whereas the other ones don't.", "topk_rank": 13 }, { "id": "corpus-178620", "score": 0.7460374236106873, "text": "Sometimes it’s not as simple as them allowing themselves to be frozen. When water is supercooled, meaning it’s at the temperature at which it freezes (or even lower) and it is very still, it can still be in a liquid state. All it takes is a little bit of agitation to freeze over. Agitation like that of a fish swimming through it or a fox jumping into it. Like [this](_URL_0_). [Here’s](_URL_1_) a video of supercooled water freezing with agitation in bottles.", "topk_rank": 14 }, { "id": "corpus-304265", "score": 0.744206964969635, "text": "First question: Yes, the freezing point works the same way regardless of whether it's pure or a solution. Second question: No, much as where distillation results in a vapor with a higher ethanol content (initially), freezing results in ice with a lower alcohol content (initially). You could say this is because ethanol has a different solubility in liquid water compared to ice. Enriching stuff that way is known as [fractional freezing](_URL_0_), and it's occasionally done with ethanol. But it can't be used to concentrate ethanol to the extent that distillation can. (as the article points out, one shouldn't think of it as the alcohol and water freezing separately; that's not how it happens. Nor does distillation result in that kind of separation)", "topk_rank": 15 }, { "id": "corpus-103253", "score": 0.743587851524353, "text": "There's kind of 2 parts to it. 1. You can supercool the liquid inside, which brings it below its normal freezing temperature, but ice crystals can't really form out of nowhere. They need a nucleation point, which is some irregularity that allows the crystals to start from, then new ice crystals can form from those crystal and create a chain reaction to build the lattice structure of ice. The nucleation site can be as simple as a bubble that forms when the container is moved. 2. Specifically for carbonated beverages, when you open it and release the pressure, CO2 is released from the liquid. When you dissolve stuff in water, you lower the freezing point (i.e. it has to be colder than 32F or 0C to freeze - this is why they salt icy roads). So the water with the carbonation has a lower freezing point, but when you release the CO2 from the solution it becomes closer to normal water, which raises the freezing point back closer to 32F/0C.", "topk_rank": 16 }, { "id": "corpus-308257", "score": 0.7426904439926147, "text": "For the same reason that ethanol and water don't separate in your vodka. Even though they have different densities, they are miscible.", "topk_rank": 17 }, { "id": "corpus-178051", "score": 0.741138756275177, "text": "Water expands when frozen, and beer is mostly water. This expansion causes the can to burst. The same happens with other drinks that are likely to freeze in coolers, but the same doesn't happen with hard liqours.", "topk_rank": 18 }, { "id": "corpus-299929", "score": 0.7410903573036194, "text": "One of two things happen: The container fails and leaks (this happens when you put a beer bottle in the freezer for too long). The water forms an exotic phase of ice with a different crystal structure that can only exist at high pressures. The first is more likely.", "topk_rank": 19 } ]

[ { "id": "corpus-325340", "score": 0.667246401309967, "text": "This is a property of mixtures. If subtance A freezes at some temperature T1, and substance B at another T2, then the freezing temperature of their mixture varies from T1 to T2 as you add more substance B. In essence this property comes from Gibbs free energy considerations." } ]

[ { "id": "corpus-161019", "score": 0.6338817477226257, "text": "As water solidifies into ice, water molecules arrange themselves into a crystalline structure [that looks like this.](_URL_0_) Because there's much more space between the molecules when they are arranged than when they're free to move as a liquid, there's also the need to occupy more volume to hold the same amount of molecules. This is also the reason why ice is less dense than water and floats. I hope this can answer your question!", "topk_rank": 0 }, { "id": "corpus-312030", "score": 0.633844792842865, "text": "It's definitely a mixture. Though it is neat to mention that alcohol and water do form an [azeotrope](_URL_0_), which can make separating them a headache. Edit: There is probably some [hydrogen bonding](_URL_1_) going on as well, granted that's all intermolecular rather than intramolecular which I assume is what you meant.", "topk_rank": 1 }, { "id": "corpus-2313916", "score": 0.6337953209877014, "text": "Is there anything I can put in her water to prevent this that's safe to drink? I can give her warm water in the evening but it still might freeze. It gets down to about -3 Celsius here. We have a dog inside so we can't bring her in the house.", "topk_rank": 2 }, { "id": "corpus-170211", "score": 0.6336734294891357, "text": "When water freezes, the Hydrogen atoms are relaxed enough to go from forming bonds with 3 neighbors to 3.4 neighbors. In order to do this, the have to rearrange - rotate slightly. Say you're a water molecules, which way do you rotate? If your neighbors all agree to a direction, the choice is obvious, if not, you might not be able to decide. Water needs a nucleation material, something like other crystals to cause it to align one way or the other.", "topk_rank": 3 }, { "id": "corpus-562174", "score": 0.6335815787315369, "text": "I have a Samsung RF197ACRS that recently began the what looks to be common sheet of ice under the crisper / water / ice in crisper problem. I took the centre panel off last week and the drain was indeed frozen. Managed to thaw the line with warm water and a turkey baster until the water freezly drained again. It worked for a week but it's starting to do the same thing again. Is there an underlying issue as to why it would re-freeze after a week? I added a peice of copper wire like many have suggested online but it must not have been enough to keep it from freezing again. Samsung will be sending in one complimentary repair so I'm waiting for that but I'd like to know if there might be an underlying issue I should bring up. It seems like fruit or veggies that are on the shelf above the crisper are also being prone to getting frozen. Watermelon and cucumber have both frozen in that area. The fridge was bought in 2014 and this all started about a month ago. Temperature is set to 3 degrees celcius as recommended, and I confirmed it has been sitting at 3 with a meat thermometer in the fridge. \n\nThanks in advance.", "topk_rank": 4 }, { "id": "corpus-176070", "score": 0.6335743069648743, "text": "Alcohol and water are mutually soluble. Like salt or sugar, alcohol (specifically ethanol here) molecules will stay in the liquid solution indefinitely. Contrast that to most oils, which are *not* water soluble and will separate into distinct layers based on density.", "topk_rank": 5 }, { "id": "corpus-185687", "score": 0.6335048675537109, "text": "I mean, it isn't 90% water, but that being said, alcohol causes your kidneys to produce more urine. That urine has to be made of of what's in your body, so more water is drawn from your body than you put in.", "topk_rank": 6 }, { "id": "corpus-167618", "score": 0.6334871649742126, "text": "H2O molecules bond to other H2O molecules with a bond called hydrogen-bonding. This happens because oxygen atoms hog all of the electrons of their shared bond with hydrogen, so the hydrogen atoms get slight positive charge and the oxygens get a slight negative charge. So you have a lattice of H2O molecules bonding to each other. The important thing to remember with hydrogen-bonds is that they have to have a certain geometry. In the liquid state, the molecules move around each other and these hydrogen-bonds are only temporary. Since they are temporary, the bonds don't have to have that certain geometry I mentioned earlier, and this means the molecules can actually get closer together. In the solid state, all of the hydrogen-bonds are formed into a very specific geometry, and this spreads the molecules out relative to the liquid state. Spreading them out gives the bulk solid a lighter density, which makes ice float.", "topk_rank": 7 }, { "id": "corpus-279647", "score": 0.6334654688835144, "text": "Formation of small ice crystals is energetically unfavorable because of their high surface-to-volume ratio. So even though it is energetically advantageous for water to turn into ice when the temperature is below 0C, the process sometimes cannot start because the first ice crystals would need to be very small. It serves as a potential barrier for solidification. Introducing a crystal of ice into overcooled water triggers solidification because the ice can now grow on existing ice surface.", "topk_rank": 8 }, { "id": "corpus-292340", "score": 0.6333192586898804, "text": "If it's completely filled such that there's no air, the bottle is completely rigid, theres no particulate, and *you don't rotate it* the water will effectively be like a rigid body and not move at all. You need some kind of force differential to get things to move relative to one another, and assuming the fluid to be incompressible it's sort of like shaking a cylinder of solid metal. If you apply angular momentum though, the fluid wants to stay at rest, but the other fluid is driven by friction, and you create a shear stress in the fluid. Unlike a solid, a fluid deforms in the presence of any shear stress.", "topk_rank": 9 }, { "id": "corpus-104758", "score": 0.6333050727844238, "text": "One reason can be air bubbles caused by dissolved gasses and changes in pressure or temperature. If it clears up after a minute or two of standing still in a glass, it's just air bubbles.", "topk_rank": 10 }, { "id": "corpus-272289", "score": 0.6333017349243164, "text": "The tip of your tongue will freeze, and in the process will bind on to the surface that chilled it. Water has a tight grip- look at what a pain in the arse it is to scrape ice off a windshield, for example. Pouring water on your tongue simply melts the ice that was keeping your tongue attached.", "topk_rank": 11 }, { "id": "corpus-303247", "score": 0.633294939994812, "text": "The hydrogen bond character of water causes it to expand when it cools. In bulk water, there is a constant shifting of hydrogen bonds as the water molecules move around. There is enough energy for the water molecules to break and reform hydrogen bonds at room temperature. As the temperature decreases, the molecules have less energy to overcome the hydrogen bonding. As it approaches the freezing point, the molecules arrange by the hydrogen bond positions which forces the water molecules into a position with more open space which is why the bulk material expands.", "topk_rank": 12 }, { "id": "corpus-275892", "score": 0.6332505941390991, "text": "It's actually at low temperatures and pressures that increasing the temperature of water can cause it sublimate (go directly from solid to gas). [Check out the phase diagram of water.](_URL_0_)", "topk_rank": 13 }, { "id": "corpus-18950", "score": 0.6332255005836487, "text": "Drinking water doesn’t do anything, unless you dilute the alcohol beforehand. Any amount of alcohol damages your body’s cells.", "topk_rank": 14 }, { "id": "corpus-1252591", "score": 0.6331794857978821, "text": "So.. My fridge broke down last week and while I was waiting for a new one to arrive, I was using an ice cooler. When I got the new fridge I emptied everything except for a bottle of wine, ice packs and bought ice... I totally forgot about it all week. I went to open it thinking its just all melted... Not only is it melted, the water is murky and stinks like nothing I've never smelt before... I flushed this ice water down the toilet before I could puke. My question is, why did it do this, and is it dangerous to drink this bottle of wine that has been siting in this sludge or should I throw it out? I really don't feel like contracting gastroenteritis or dysentery..advice please?", "topk_rank": 15 }, { "id": "corpus-10224", "score": 0.6331773400306702, "text": "The object is floating in the water. As you tilt the glass to drink, the object continues to float in the liquid (after all, water ~~is heavier than the object, and air is lighter than the object and the water~~ its mass is higher), which means the object will go up as you tilt your glass. This is why it's hard to swallow an ice cube, unless you take large gulps.", "topk_rank": 16 }, { "id": "corpus-158884", "score": 0.6331589221954346, "text": "Antifreeze doesn't melt ice. It just prevents water from becoming ice when it gets cold. The antifreeze molecules — which are usually ethylene glycol — get in between the water molecules and prevent crystals from forming, so the water stays liquid below the freezing point. But once the crystals have formed, antifreeze won't magically melt them. That takes heat.", "topk_rank": 17 }, { "id": "corpus-287131", "score": 0.6331161856651306, "text": "Both ice and water can exist a zero degrees Celsius. You have to add about 80 calories a gram to ice (the heat of fusion) to cause it to convert to water at zero degrees Celsius. After this point each calorie added will raise the temperature of one gram of water one degree Celsius. Same for liquid water. You have to remove the same amount of heat from zero degree water to form a gram of ice at zero degrees Celsius. Continue removing heat and the temperature of the ice will drop.", "topk_rank": 18 }, { "id": "corpus-307776", "score": 0.6331117153167725, "text": "Salt lowers the melting point of the ice. But what does this mean? The heat flows out of the beer like this: beer - > bottle or can - > water - > ice (melting it into water) The water is essentially acting as a \"cooling interface\" between the warm thing (the beer) and the cold thing (the ice). Adding salt to the water allows the water to remain colder in liquid form. So this means we get a much better cooling interface in the mix: beer - > bottle or can - > water - > colder (just melted) water - > ice This speeds up the cooling process because the heat can move faster through the cold liquid water than it can through solid ice. The colder water that just melted from the ice into the saltwater is almost like a \"heat lubricant\" (in a very abstract way). Edit: corrected mistakes", "topk_rank": 19 } ]

[ { "id": "corpus-325341", "score": 0.7330203652381897, "text": "> I have heard before (can't remember where) that Jupiter is on the threshold of becoming a star [You heard wrong](_URL_0_). The very lowest-mass brown dwarfs, that barely produce any heat at all and can only fuse deuterium, would theoretically be no less than 13 times as massive as Jupiter. And these ultra-low-mass stars would cool to the point that they can not fuse anything on the order of a few million years, many many times younger than our solar system. The lowest mass true stars ([red dwarfs](_URL_1_) which fuse normal hydrogen) are about 75 times the mass of Jupiter." } ]

[ { "id": "corpus-191906", "score": 0.6957257390022278, "text": "Mass. The stars smaller than Jupiter are more massive, and denser, massive enough to actually start undergoing nuclear fusion. Jupiter just doesn't have the mass to do so.", "topk_rank": 0 }, { "id": "corpus-299611", "score": 0.6951471567153931, "text": "I think the brown dwarf would just get eaten by the red supergiant with an uneventful fizzle, much like a meteorite impact on a gas giant. A brown dwarf has to be smaller than 0.01 solar masses, otherwise it would be a red dwarf or something else that can sustain nuclear fusion reactions in its core. A red *super*-giant has to be heavier than 10 solar masses, which means it's being hit by a lump of gas 1/1000 its own mass. Just from that separation of scales I don't think all that much would happen, apart from some exciting fireworks at the point of impact. However, like 0acht15 pointed out, it may result in a nova explosion, though I doubt it would destabilize the whole supergiant.", "topk_rank": 1 }, { "id": "corpus-104934", "score": 0.6951191425323486, "text": "> Why don't stars, like our sun, ever run out of gas to burn? They do. Our sun will run out of gas in a few billion years. > Shouldn't it all explode in one massive explosion? No. A star begins as a cloud of gas that starts to pull inward due to its own gravity. When it gets dense enough that hydrogen starts to fuse, that's what causes it to ignite. But the energy released heats the gas up, hot gas will try to expand. - When it expands, that reduces its density and not as much fusion occurs, making it cool down, which allows it to contract. - When it contracts, that increases its density and more fusion occurs, making it heat up, which will make it expand. So eventually you get an equilibrium where any tiny amount of contraction or expansion will be reversed. The equilibrium persists until the star runs out of fuel, at which point one of several different endgames can happen depending on the star's size.", "topk_rank": 2 }, { "id": "corpus-317951", "score": 0.6938178539276123, "text": "You need ~10 times the Jupiter mass, that needs multiple collisions. The planets would collide with speeds of tens of kilometers per second, and the pressure differences would propagate at least with similar speeds. At that speed you need something like an hour to have the impact affect everything. Shockwaves from the impact would probably trigger fusion even earlier.", "topk_rank": 3 }, { "id": "corpus-323815", "score": 0.6929976344108582, "text": "At a certain size, the planet would have so much mass that it would collapse and form a star, and if you added even more mass it would easily become a black hole. The cutoff point between a planet and a star (specifically a brown dwarf star) is around 11-16 jupiter masses.", "topk_rank": 4 }, { "id": "corpus-159817", "score": 0.6928474307060242, "text": "Think of it this way: To start fusion, the star has to reach critical mass and critical density. Start as a cloud, gravity between atoms attract each other and condense. When you condense stuff, there's higher pressure, and compression causes the cloud to heat up. This goes on for a while, slowly heating up and increasing pressure. Eventually, it hits that critical density, temperature and mass. Remember nuclear fusion is a self-sustaining reaction, so it just goes boom. So the answer to your question is it heats up slowly without fusion, and ignite immediately. At least according to my understanding of star birth.", "topk_rank": 5 }, { "id": "corpus-312771", "score": 0.6925584077835083, "text": "Hi Urisk, > What would happen to Jupiter if it moved gradually closer to the sun? It would completely disrupt the inner solar system. The planets Mercury to Mars and the objects of the asteroid belt would be ejected from the solar system, shot into the sun or flung into highly eccentrical orbits at a minimum. > Could it survive at a distance as close as Mercury? Sure. There is a whole bunch of massive (exo)planets, orbiting their host stars very closely. They are called [hot Jupiters](_URL_0_) and their orbits range roughly from 0.015 to 0.5 AU. As a comparison, Mercury has a semi-major axis (average distance to the sun) of 0.387 AU.", "topk_rank": 6 }, { "id": "corpus-310877", "score": 0.6923013925552368, "text": "There is such a thing as a Rouge Star - A star that has been ejected due to intense gravitational stresses. Usually happens when two galaxies collide and there are other reasons but I don't feel like opening another tab. The thing is, gravitational influences felt on a solar system level to the rest of the galaxy are rather small, so if a star was ejected, and nothing came that close to it (relatively speaking) like another star or planetary body - The planets orbiting said rouge star wouldn't really notice much. If the sun suddenly was by itself, we wouldn't experience much more than a dimmer sky at night. We'd probably actually be safer since the chance of a gamma-ray burst or supernova wouldn't even be a problem anymore.", "topk_rank": 7 }, { "id": "corpus-260171", "score": 0.6914587020874023, "text": "Adding mass to a star won't prolong it's life, it will shorten it, as the increased mass will provide more pressure at the core, increasing the rate of fusion. I doubt adding Jupiter's mass to the sun would make much of a difference though.", "topk_rank": 8 }, { "id": "corpus-268094", "score": 0.6909210681915283, "text": "It's not a question of if, it's a question of how many. It's also not a matter of a star \"self-destructing\" and leaving a planet to roam around the stars, such events would dramatically alter or destroy planets. What's vastly more likely is a process where orbital dynamics and resonances between planets, especially the more massive ones, to be ejected. That's how the Oort cloud was created in our Solar System, cometary bodies were sent out to distances of thousands of AU or ejected entirely from our system during its early history. Similar mechanics can also eject larger planets, potentially even as large as Jupiter. Almost certainly there are millions if not billions of such planets in our galaxy.", "topk_rank": 9 }, { "id": "corpus-323105", "score": 0.6904546618461609, "text": "Fun fact: It's entirely possible to have a planetary only system in which there was never enough mass to form a star. Then you could have a big Jupiter of some kind at the middle being orbited by some rocky planets...all of it very cold and dark flying through the void. These would be called \"sub-brown dwarf stars\" or \"Rogue planetary systems\"", "topk_rank": 10 }, { "id": "corpus-280220", "score": 0.6896005272865295, "text": "As a rule, no. The Helium in Jupiter was there when the planet formed. Even with a planet as large as Jupiter, the core regions don't reach high enough densities and temperatures to start Hydrogen Fusion. In fact there's a whole class/spectrum of objects that span the gap between Jupiter (clearly a Gas Giant) to M-type Stars, the smallest stars that undergo core Hydrogen Fusion. These objects are called Brown Dwarfs. Its unclear if these objects are just runaway Jupiters that get huge (10-20x the mass of Jupiter), or if they're failed stars that don't collect enough mass to reach core burning. The largest of these Brown Dwarfs can sustain some fusion, typically Deuterium and Tritium, but can't sustain full Hydrogen burning.", "topk_rank": 11 }, { "id": "corpus-322167", "score": 0.6895266175270081, "text": "If you were to start with a gas planet consisting of mainly hydrogen, and keep adding hydrogen, you'd get to about 80 Jupiter masses before its core heat and pressure would start fusing hydrogen and become, by definition, a star. However, if you were to start with a rocky planet, and keep adding elements heavier than lithium, because those elements require far greater pressures and temperatures to undergo fusion, I imagine that the limit would instead be the Chandrasekhar limit of 1.44 solar masses (which is not heavy enough to fuse carbon or anything heavier), if the planet was not rotating. At that point, the force of gravity would overcome electron degeneracy pressure, and your planet would become a neutron star.", "topk_rank": 12 }, { "id": "corpus-323691", "score": 0.6891594529151917, "text": "Very little, presumably. Even a \"little\" star is orders of magnitude larger than a \"big\" planet. The largest planet we've ever seen, WASP-17b, is roughly 1.7 times more volume than jupiter (and, roughly, about the same mass) The smallest star (And I'm hesitant to call it a \"star\", seeing as it doesn't maintain the fusion reactions we come to expect from \"stars\", as such it's a very 'dark' object) we've ever encountered, OTS 44, is 1% the size of our sun, but is still 12 times as heavy as jupiter. Outside of outliers, a \"big\" planet would simply be annihilated by the massive gravitational pull of the star. A big star wouldn't even notice in any sort of magnitude scale the difference a small planet would cause it.", "topk_rank": 13 }, { "id": "corpus-310901", "score": 0.6880524754524231, "text": "An Earth-like planet crashing into its star is less like a crash than it is like a gnat flying into a campfire. The planet would vaporize as it falls into the deeper layers of star.", "topk_rank": 14 }, { "id": "corpus-316397", "score": 0.6874281167984009, "text": "As others have said, a brown dwarf on its own can't become a true star--the sticking point being, \"on its own.\" If two brown dwarfs merge, they could result in a single stable, hydrogen-fusing red dwarf, provide the combined mass is above the ~80 Jupiter-mass limit. I suppose it's also theoretically possible for a brown dwarf to accrete enough mass from a close companion to bring itself to the minimum mass necessary for fusion.", "topk_rank": 15 }, { "id": "corpus-302276", "score": 0.6873757839202881, "text": "Technically stars aren't *on fire*. A star *ignites*, as remarcsd says, when gravity compresses together the hydrogen in its core to the point that the atoms fuse together. Fusion releases vast amounts of energy, some of which reaches us as light.", "topk_rank": 16 }, { "id": "corpus-323422", "score": 0.6866657137870789, "text": "Sure, if you multiplied its mass by 80 or so. Like stars in general, its composition is approximately that of the universe in general--mostly hydrogen with some helium and then some trace elements. But in order to get enough pressure and temperature going in the core for sustained proton-proton chain fusion, you'd need to pile on a lot more mass. Theoretical models put that minimum mass in the range of 70-80 times the mass of Jupiter. And even then, it would not be a very luminous star, only putting out around a thousandth as much power as the Sun.", "topk_rank": 17 }, { "id": "corpus-301793", "score": 0.6866655945777893, "text": "The sun won't explode. For a star to supernova (\"explode\"), it needs to be at least about 10 times as massive as our sun. If we replaced our sun with a star that massive, the ejecta from the supernova would destroy all of the planets in the solar system, and there is virtually no possibility any type of life could survive the explosion and the drift through interstellar space for millions of years. What you're probably thinking of is when the sun will enter its [red giant phase](_URL_0_). At this point, it will increase in radius to approximately the orbit of the Earth, swallowing all closer planets. (Mars will probably be scorched but unabsorbed.) In this scenario there's no ejection of chunks of Earth that could spread life, and as before, even if there were, the temperatures involved would likely sterilize all life on the escaping chunk.", "topk_rank": 18 }, { "id": "corpus-311750", "score": 0.6864674091339111, "text": "The minimum mass for a star to sustain fusion is around 0.1 solar masses. Jupiter is only 0.00095 solar mass, so even if you initiated a fusion reaction at its core it would not be sustained. When a gas giant reaches around 13 times Jupiter's mass we start calling those Brown Dwarf stars. These are basically gas giants that would have started fusion in their cores when they formed, but could not sustain the fusion.", "topk_rank": 19 } ]

[ { "id": "corpus-325342", "score": 0.6787060499191284, "text": "I'm not sure the answer is as scientific as you might think. I'm pretty sure oil companies would rather you depend on them, than you be able to just plug in every time you park your car. Give it a few years, and the infrastructure might be there in enough places to justify the masses purchasing electric only vehicles." } ]

[ { "id": "corpus-300264", "score": 0.6447659134864807, "text": "Short news piece with numbers [here](_URL_0_) (unfortunately, original article unavailable). Summary (trusting their numbers): making a new Prius costs 1,000 gallons of gas. A Prius (45mpg) would have to drive ~16,000 miles to catch up to a 12mpg used car whose manufacturing costs are already paid off. A higher-mpg used car (say an old civic, mine's 30 mpg) would take 90-100K miles.", "topk_rank": 0 }, { "id": "corpus-90974", "score": 0.6447606086730957, "text": "Because they are *oil companies*. They have billions of dollars in infrastructure around the world, thousands of staff members, all that surround the extraction and production of oil. Leading the innovation on alternative energy is just hastening their obsolescence, when all that infrastructure becomes extraordinarily expensive paperweights.", "topk_rank": 1 }, { "id": "corpus-2460455", "score": 0.6447477340698242, "text": "Without getting too much into politics, you may already know by now that by 2030 the sale of new diesel/petrol cars will stop (besides cars like Toyotas Prius as it a hybrid). However, you could still sell second-hand cars (rule only applies to automotive companies). \n\nI'd imagine though that taxes are going to skyrocket for diesel/petrol cars in 10 years time to make people get electric cars despite them being expensive. Also I think that there would be more congestion charges at higher prices in more locations. \n\nThe reason I ask this is that in around 5 years when I've saved up the money, I'd like to get a classic car which would obviously run of diesel/petrol. But because older classic cars produce more carbon emissions, I wouldn't want to be paying top dollar on taxes and congestion fees due to having a high carbon emissions car.", "topk_rank": 2 }, { "id": "corpus-130342", "score": 0.6447103023529053, "text": "Generating power in mass quantities at a central location is at minimum a far more efficient way to use the energy in the coal, though I understand your point that driving an electric car that charges on fossil fuels is not exactly ideal, its at least marginally better than burning fuel as-needed on the fly in your tiny inefficient engine", "topk_rank": 3 }, { "id": "corpus-86286", "score": 0.6446748971939087, "text": "Fuel is what makes power in an engine. Burn more fuel, and you can make more power. In most engines, getting more fuel into the cylinders is pretty easy. The issue is that getting more oxygen into the cylinders can be hard. More oxygen is needed because fuel really only burns well in a fairly narrow range of fuel:oxygen ratios. Even with turbo- or supercharging stuffing more air into the intake, air is mostly inert nitrogen, so adding more air, while helpful, has a limited effect. Nitrous oxide, however, is a fairly potent oxidizer, and it has much less inert nitrogen in it than air does. By making a system that injects NOx into the cylinders along with additional fuel, you can deliver a large amount of fuel:oxidizer mix to the engine on demand, and make much more power. In short, NOx allows you to burn more fuel.", "topk_rank": 4 }, { "id": "corpus-403958", "score": 0.644571840763092, "text": "1. Volkswagen e-Golf, electric\n1. BMW i3, electric\n1. Toyota Rav 4, Hybrid\n1. Tesla Model X, electric\n1. Mitsubishi Outlander, plugin hybrid\n1. Toyota Yaris, hybrid\n1. Tesla Model S, electric\n1. Nissan Leaf, electric\n1. Volkswagen Passat, plugin hybrid\n1. Toyota Auris, hybrid\n1. Toyota C-HR, hybrid\n1. Mercedes-Benz GLC, plugin hybrid\n1. Renault Zoe, electric\n1. Volvo V90, diesel\n1. Volkswagen Golf, plugin hybrid\n\nSo the only car with ICE only is in 14th place. All other cars have some form of electric propulsion.\n\nBroken down in to engine types it looks like this:\n\n* Diesel: 23.1%\n* Gasoline: 24.7%\n* Hybrid & plugin hybrid: 31,3%\n* Zero emission: 20.9%\n\nSource \\(in Norwegian\\)", "topk_rank": 5 }, { "id": "corpus-2675411", "score": 0.6445091962814331, "text": "So I’ve always wondered this. Alot of people always insist on using electrical things rather than using fossil fuels, which can be seen from modern cars like Tesla which runs on electricity instead of fossil fuels. The world consumes so much electricity every single day, how do we not run out of it? Is there a renewable source that we are getting this from. Not talking about wind because the electricity it gives varies and is not good enough. Where the hell are we getting this much electricity from?", "topk_rank": 6 }, { "id": "corpus-2022896", "score": 0.6444971561431885, "text": "Whenever people are faced with a problem, their first response is \"take it out at the source,\" without considering the benefits the source brings and how it could be improved in order to get rid of the problems. Jet planes causing pollution? Don't try to invent eco-friendly jet engines, keep people from flying and/or force them to use slow-as-hell electric propellor planes that only fit half a person and probably couldn't get from Manhattan to Brooklyn on a full charge! Nuclear plants creating dangerous waste? Don't try to come up with a way of reusing or safely storing/disposing of it, just ban any form of power generation that deals with atomic nuclei, thereby either sending us back to the dark ages, relying entirely on other types of emission-free power generation and thus causing blackouts for anyone in a place that doesn't have access to hydroelectric or geothermal whenever the sun isn't shining/wind isn't blowing (and don't give me that battery BS; Elon Musk is full of shit), or increasing the demand for fossil fuels and thus doing more damage to the planet! Big corporation abusing its power? Don't try to enact rules and regs that would limit its power but keep it and its goods/services present, overthrow the entire system and plunge the world into complete chaos! Single-use plastic screwing up the ocean? Don't try to make more biodegradable plastic and/or make it easier to recycle plastic, no no, just unilaterally ban all plastic! People don't want to create, they just want to destroy, and it pisses me off!", "topk_rank": 7 }, { "id": "corpus-20742", "score": 0.6444753408432007, "text": "Some states like Washington and California have heavy taxes imposed on gasoline by the state government. California's high prices are also due to their required emissions laws, while Washington State's are due to part of the gas tax going to pay for public transit and infrastructure maintenance. States with cheap gas don't have these taxes on fuel. Also, some states like Texas, North Dakota, and Oklahoma also have a lot of oil refineries that help keep the prices low for local consumers. The farther a tanker has to travel with the gas also influences the price you pay at the pump.", "topk_rank": 8 }, { "id": "corpus-279793", "score": 0.644469141960144, "text": "Cost and mass. Everything is about cost but the mass required to have the same stored energy as the chemical energy in a battery would require it to move very fast. Fast moving heavy objects introduce significant stresses and if a failure occurs its like a bomb going off. Also these things cant be carried around like a battery simply due to velocities required and stresses induced for any amount of energy in a small package.", "topk_rank": 9 }, { "id": "corpus-43407", "score": 0.6444355249404907, "text": "Because airlines cost so much more per hour to operate than a car, they need to do two things to make it cost-effective: 1) Get as many paying customers on the plane as possible 2) Make the plane as light-weight as possible. For the former, this means small seats with very little space in between them (both to the sides and front-back). For the latter, this means making seats that are as light-weight as possible, often at the expense of comfort. Both space and weight are also concerns for cars, but not nearly as *much* of one due to drastically lower fuel costs. As well, cars are made with the expectation that any given person will spend an hour or more per day in it; with planes, most people (besides those who travel frequently for work) rarely spend more than a dozen hours per year on a plane. Comfort just isn't as important.", "topk_rank": 10 }, { "id": "corpus-1385072", "score": 0.6444315314292908, "text": "I'm curious to see if anyone just couldn't stand to live without their petrol car, or if anyone had an experience that just wasn't good enough. Do you remember anybody who has switched from a Tesla to an ICE?", "topk_rank": 11 }, { "id": "corpus-173872", "score": 0.6444253325462341, "text": "Hydrogen gas is passed over a catalyst which strips electrons from the protons. The protons pass through a Proton exchange membrane that only protons can pass through. The electrons are sent around it through a circuit acting as electricity. On the other side oxygen is run over a catalyst which reacts with the free protons coming through the membrane and free electrons coming from the circuit to create water. So you have H2 and O2 going into the system and you have heat, electricity and H2O coming out. With the electricity powering the car and the heat basically helps keep the water from freezing in cold weather, but still requires some insulation. _URL_0_", "topk_rank": 12 }, { "id": "corpus-307301", "score": 0.644418478012085, "text": "There's already operational plants that pull it from the air, mix it with water and electricity and creates a hydrocarbon fuel that can be burned in cars. To pull JUST the carbon from the air, you gotta either separate it, and/or combine it with another compound, which you can remove it from. Creating a hydrocarbon fuel is probably the best thing we can do NOW. We can use solar and water to create \"gasoline\", which removes carbon from the air. It would be a self sustaining system, in that we pull carbon from the air to put it back in gas and then back to the air again. We only need a renewable source of energy like solar or fusion to power it.", "topk_rank": 13 }, { "id": "corpus-125486", "score": 0.6444094777107239, "text": "The short version: plastic is made from oil. When they take it out of the ground it is a mixture of a LOT of similar compounds. They distill it to separate out the useful ones for making plastic, then the less useful ones go to gasoline if they are liquid, or tar type stuff if they are solid. The plastic ones specifically they react together to link hundreds of thousands of the same molecule together, resulting in plastic. The properties of the plastic (e.g. milk jug vs plastic bag vs bouncy ball) depend on the type of starting molecule. It's quite a bit more complicated than that, but I think that is as close to ELI5 as I can get without being condescending.", "topk_rank": 14 }, { "id": "corpus-77867", "score": 0.6443910002708435, "text": "Octane rating (the numbers you're describing) are a measure of how much you can compress the fuel before it ignites. Fuel that ignites before the piston in your engine is entirely compressed, or fuel that doesn't ignite all at once is very undesirable and can result in a lot of wear on your engine (as well as simply being inefficient). Most engines operate just fine with regular fuel. Only very high performance engines (that require that the fuel be compressed to a high degree before igniting) really need high octane fuel.", "topk_rank": 15 }, { "id": "corpus-291665", "score": 0.6443897485733032, "text": "Current battery technology *sucks* compared to our ability to produce/harvest energy. It's much easier to build systems that release energy than it is to build a system that can absorb and efficiently re-emit energy. Chemical batteries are large, expensive, and (as the name suggests) full of volatile chemicals. There exists due to the specific chemistry a hard limit to how fast and how often they can be charged, and in most cases it isn't economically feasible or physically practical to try and store the energy compared to just letting it dissipate as heat.", "topk_rank": 16 }, { "id": "corpus-2674894", "score": 0.644381582736969, "text": "Climate change is big topic recently. Politicians says we need to switch to green energy. Skeptics says that the green energy isn’t really green. And i would like to know how it really works.\n\nWhen you build a solar power plant you need to invest lot of energy and material to build it. And it doesn't have a long durability. Then you have solar panel to recycle it/or thrash it. You also have to build some other power plant to switch on during night, when solar power plant does not produce any energy. Or you have to build something to store energy from day to night. When you sum everything up, is really solar energy more eco-friendly than fossil fuel energy? Same question goes to other sources of „green energy“?\n\nWhat about electric cars? If electric cars would be mass spread, we would need to build more power plants to feed them. We would need to build infrastructure. When you sum everything up, are electric cars eco-friednly?", "topk_rank": 17 }, { "id": "corpus-1358861", "score": 0.6443785429000854, "text": "So I have a Tesla model 3 and it gets great gas mileage, and i heard that diesel is more efficient than gas and it consumes less, so I was wondering. Should I fill it up with diesel next time its empty? My father fills it up every weekend so I figured I could surprise him by doing that! What do you think? Also have heard something of turbocharging, that it increases efficiency. Any advice?", "topk_rank": 18 }, { "id": "corpus-2460539", "score": 0.6443073749542236, "text": "Hey! \nI am in the market for a hybrid or electric car. I am just beginning my research and wondered if you had some pointers or advice? How does shopping differ from a gas engine? \nWhat questions should I be looking for the answer to? \nThanks?", "topk_rank": 19 } ]

[ { "id": "corpus-325343", "score": 0.7560204267501831, "text": "While pesticides/agrochemicals are generally much more soluble in organic solvents, rinsing with water and rubbing the vegetables will still help quite a bit. This is because most of the pesticides will be absorbed by the dirt/dust on the outside of the vegetable, and if you get this physically removable material off the outside of the plant the majority of the pesticides will go with it. In addition, many pesticides are somewhat water soluble, so rinsing will help directly as well. As to whether or not you are taking in a lot of pesticides, the answer is more up in the air than you think. I do work with sample preparation of fruits and vegetables for pesticide analysis, and it is very hit and miss. 99% of the real world samples tested have no pesticide residue, but the few that do have *a lot* of pesticide. There is a reason I purchase organic fruits and vegetables." } ]

[ { "id": "corpus-267306", "score": 0.7061284184455872, "text": "If the fruit boy at the supermarket picked his nose before stacking the apple that you bought, then yes, washing it is a good idea. A lot of people touch your apple before you buy it, and it may have fallen on the floor. If you are not a native to a certain country, such as Thailand, and not used to their tap water, it probably contains microbes that will make you sick. When traveling to other countries, it's best to wash fruits and veggies with boiled or bottled water. Tap water is not guaranteed to be safe for everyone. I'm not familiar with what's in LA's water, so I can't comment on it specifically.", "topk_rank": 0 }, { "id": "corpus-849321", "score": 0.7016933560371399, "text": "I know fruits are supposed to be in the fridge but do I wash them before putting them in ? \n\nFor veggies (potatoes, cucumber, eggplants....) do i need to put them in the fridge ? If so, do I need wash them before ?", "topk_rank": 1 }, { "id": "corpus-686102", "score": 0.6999568939208984, "text": "I hate the taste and texture of most healthy food so I've started blending/juicing (i'm not certain which term is correct) different fruits and vegetables to help introduce more of them into my diet, however someone said that putting them in a blender breaks apart the proteins and nutrients they provide so its less heathy than just eating it. My first thought was thats a load of nonsense,but just to be sure i looked around the Internet but couldn't really find an answer. since this sub reddit is pretty reliable when it comes to facts i thought I'd ask here if its true or not, I'd hate to be wasting time and money blending stuff if its not beneficial.", "topk_rank": 2 }, { "id": "corpus-21414", "score": 0.6997697949409485, "text": "If it's black and/or shiny, don't risk it! But other than that, you can have the rest of the bunch of they're clean, and better yet, you can even have the moldy fruit if you cut off the contaminated part! (plus a few cm extra for a margin of safety, they can penetrate deeper than what you can see with your eyes) For extra safety, rinse the fruit off. For even more safety wash with soap. Even more, very hot water and soap. One step further, soak in a concentrated heated salt bath then wash with soap and rinse. Above all else, smell, then taste. If either make you feel 'off' DON'T EAT IT. We evolved without refrigeration and expiration dates, and there are automatic instinctual reactions to keep us alive. Trust them, and you'll be good. Source: I work in biotech and enjoy cooking (with non-moldy food)", "topk_rank": 3 }, { "id": "corpus-2517569", "score": 0.6967015266418457, "text": "I keep seeing all these “useful” things you can do with rice water. Make broth, use for soup, and even beauty uses. But I thought one of reasons you rinse rice (aside from stickiness) was to get rid of any fertilizers or pesticides? \n\nWhy would I use that water for cooking? \n\nSorry if this is a stupid question.", "topk_rank": 4 }, { "id": "corpus-72510", "score": 0.6953185796737671, "text": "As I guy that worked produce for a short stint, wash it, wash it good. The boxes produce comes in is filthy, produce falls on the floor all the time and it goes back on the shelf, and people touch the crap out of produce before picking one. So if you dont mind dirty produce, then you dont need to wash it, otherwise, wash it good", "topk_rank": 5 }, { "id": "corpus-1274316", "score": 0.6930239200592041, "text": "This is a pretty straight forward question. I just started juicing, and while I am pretty clear on what I am doing I want to make sure that I avoid some easy mistakes.\n\nIs there any fruits or vegetables I should avoid while doing a juice cleanse? Specifically, I am unsure about oranges (tangerine/clementine...any orange-like things), bananas (I know they can not go on a juicer), pineapples. Pretty much, the REALLY sweet fruits. Are these okay, or should they be avoided? Also, vegetable wise is anything going to mess me up? I have been loading my drinks with kale and spinach specifically, but I also enjoy cucumbers. I haven't tried carrots yet, as I am not a huge carrot fan, but I am hoping I can conquer that distaste if it's in juice form.", "topk_rank": 6 }, { "id": "corpus-9876", "score": 0.6876110434532166, "text": "Poop from cows, chickens, etc., is used to fertilize vegetables. Sometimes, that poop contains bacteria like e. coli which gets on the outside of the vegetables. If the vegetables aren't cleaned before people eat it, then people can get sick. The easiest way to keep yourself safe is to always wash your vegetables before eating them.", "topk_rank": 7 }, { "id": "corpus-59106", "score": 0.6851053833961487, "text": "The chemicals you treat water with are to kill organisms (bacteria, parasites, etc), not cleanse it of other chemicals. Drinking water with dead organisms in it might make you a little sick to the stomach but it won't kill you because the organisms won't multiply inside you. I suppose it's possible you could use one chemical to have a reaction with other chemicals in the water, resulting in a new chemical that isn't harmful, but I've never heard of such a thing in reality.", "topk_rank": 8 }, { "id": "corpus-318326", "score": 0.685091495513916, "text": "Washing greatly decreases the bacterial load, but doesn't sterilize it at all. Sources: _URL_1_ _URL_0_ Listeria hangs out in the soil. Since you're physically removing soil with just water, you'll pull the Listeria along with it. However, you aren't at a huge risk from Listeria anyway. It's kind of a crappy pathogen - it requires a startlingly high amount of bacteria to actually make you sick, and generally only affects the very young and old. Not saying you should ignore food safety warnings, but if I was going to eat a foodborne pathogen, it would be Listeria. Other pathogens are still a problem though, and have a low enough infectious dose that washing with water alone isn't safe. Campylobacter in particular comes to mind.", "topk_rank": 9 }, { "id": "corpus-39464", "score": 0.6807582974433899, "text": "This is absolutely not always true! Plants can *and do* absorb toxins from their environment. Now, the plant may filter some (or even all) of them out, but it might not. Some might end up in the parts of the plant you eat - **especially** if you eat the roots.", "topk_rank": 10 }, { "id": "corpus-161519", "score": 0.6807577610015869, "text": "the dishwater does a water cycle to wash off those chemicals. same with your laundry thing", "topk_rank": 11 }, { "id": "corpus-106588", "score": 0.6804535388946533, "text": "Impurities and even *toxins* in ground water can **absolutely** make it into the plants. In fact, one way that impurities and toxins can be removed form the environment is plants sucking them up! You should absolutely **not** eat plants that grew in questionable environment!", "topk_rank": 12 }, { "id": "corpus-148132", "score": 0.6789926886558533, "text": "Anything soluble in water can be washed away. That includes many chemicals like pesticides and contaminants like feces. Soap makes this washing away of things easier and more thorough, but water is much better than nothing. Water is sometimes referred to in chemistry as \"the universal solvent) because of the variety of things which can dissolve in water.", "topk_rank": 13 }, { "id": "corpus-309613", "score": 0.678869366645813, "text": "It's not about the pests as much as shelf life. A lot of fruits will spoil faster once they've been washed, and the store does not want the produce to go bad before it sells. Check out [these guidelines for proper washing of fruits](_URL_0_).", "topk_rank": 14 }, { "id": "corpus-2362979", "score": 0.6782081723213196, "text": "Fruit flies lay their eggs on bananas, melons and soft-skinned fruits. By washing the fruit immediately, you rinse away the eggs and avoid a biblical bug swarm if you like to eat certain fruits at room temperature.", "topk_rank": 15 }, { "id": "corpus-1480388", "score": 0.6739623546600342, "text": "I watched fat, sick and nearly dead and of course I was very impressed by the results and how healthy Joe and Phil looked. I've bought a juicer, and started drinking blended and/or vegetables (cucumber, celery, kale, lemon, ginger, apple).\n\nBut I have a PhD in Human Biology and I want to know what are the scientifically proven benefits of doing this? I'm **not** talking about fasting. I'm talking about juicing specifically - the addition of vegetable juice to the diet.\n\nI've tried looking for reputable information, but I get a lot of waffle like \"natural\" and \"toxins\" etc. And most of this goes against my knowledge of the human body and nutrition:\n\n* Vegetables contain enzymes - They definitely do. But enzymes are proteins, which will be broken down during digestion. I find it hard to believe that enzymes in the vegetables are biologically active in any way once they get into the lower gut. And by the time they are absorbed into the blood stream, those enzymes have been cut up into amino acids or polypeptide chunks. There is NO way that vegetable enzymes are in any way active in the bloodstream.\n\n* Chlorophyll will help \"oxygenate\" the body - this seems like absolute bullshit. There is no sunlight in the digestive tract so I'm not sure how this is possible. \n\n* Detoxing - again, it's never very clear exactly what toxins are involved or how vegetable juice removes them. The liver converts most un-needed molecules into something useful and the kidneys filter out waste products. Some toxins can build up, like heavy metals, but I have to wonder what sort of diet would lead to massive buildup of those metals to a point where they hurt our health. And I'm also not sure how vegetable juice removes them.\n\n* Vitamins and minerals - they are definitely important for human health. But I have to wonder how many of us actually have vitamin or mineral deficiencies that make us unhealthy? Even our daily crap food is quite full of vitamins and minerals. Even processed as shit white bread has iron, calcium, magnesium, folate etc in it. You'd have to eat a VERY narrow spectrum of foods to be pathogenically deficient in vitamins. And even then - what is the benefit to juicing vs taking a multivitamin? Is it the absorption? Again, I can't find proper answers without waffle like \"the body absorbs natural things better\".\n\n* Fibre - it's excellent for us, aids digestion, can even help to lower cholesterol, but juicing is removing most of the fibre content. That's why I personally do some juicing and some straight blended veggies.\n\nSo now we are down to those mysterious phytonutrients - things like lycopene. And I really don't know enough them to give serious discussion to them.\n\nI'm not saying that juicing is bad, not at all. Obviously a diet rich in vegetables and fruit is good us. But I wonder if a lot of benefit of juicing is overhyped, and most websites are promising detox, healing, curing diseases, curing cancer. But there is little explanation of what is so magical in vegetable juice. \n\nMy own feeling is that by juicing, you are making people eat more fruit and veg, pay more attention to their diet in general, and also making them feel involved in their own health. They are all good things, and I have already encouraged my friends and family to start doing it as a way of increasing vegetable uptake. But does anybody have any good input or information?", "topk_rank": 16 }, { "id": "corpus-1252596", "score": 0.6700272560119629, "text": "So before this whole coronavirus thing, I’ve used isopropyl alcohol 70% in a spray bottle to clean the kitchen. Counters, electric stove tops, handles, sinks, etc. it gives a nice polish that nothing else can compare to. \n\nBut more importantly I think it makes my countertops disinfected right? So I often put like just vegetables or breads directly on the countertop. Obviously I use cutting boards but I prep more food than I have space, and storing everything on top of plates or bowls is just extra washing for me. \n\nIs this weird? Is it hygienic?\n\nEdit: another benefit in my opinion (no scientific proof tho) is that I can spray the alcohol freely without worrying about microscopic bits flying into my food, utensils, knives, pots, pans, plates, etc. whereas a cleaner might make it a lot harder to avoid toxic substances.", "topk_rank": 17 }, { "id": "corpus-1255187", "score": 0.669475257396698, "text": "Things like chicken livers, beef livers, kidneys, intestines?\n\nEvery recipe or guide on it says yes to rinse it.\n\nMy family swears by rinsing it and then even boiling it first, for things like stomach and intestine.\n\nBut people are saying that rinsing meat is bad.\n\nSo which is it? What is the difference between rinsing chicken livers and rinsing chicken?\n\nAlso, I have some fish. Can I rinse it? I'm afraid there may be some scales leftover on it.", "topk_rank": 18 }, { "id": "corpus-2056734", "score": 0.6689796447753906, "text": "Typically I try to do something like a colon cleanse or bowel cleanse to help get this stuff out of my system faster. Is that wise?", "topk_rank": 19 } ]

[ { "id": "corpus-325344", "score": 0.8234876990318298, "text": "Historical reasons. There isn't a strict definition of what constitutes a continent. edit: It should also be mentioned that in some places, Europe+Asia are considered one continent, and in other places North+South America are considered one continent." } ]

[ { "id": "corpus-233804", "score": 0.7817624807357788, "text": "You can't be more wrong. Continents were named by ancient Greeks, as they were extremely close to the continental divide between all 3 continents of the Old World. Europe was named after the goddess Europa, Asia is of unknown origin, as is Africa. All other continent names were created in modern ages by Europeans, aptly chosen to mimic the old names by beginning and ending at A. America after Amerigo Vespucci, Australia after Terra Australis and Antarctica (discovered only after Australia was named) was named \"opposite of the Arctic). It's also important to note that the division between Europe and Asia is based on the old Greek concept, as there is no real tectonic division between the European and Asian part of Eurasia.", "topk_rank": 0 }, { "id": "corpus-253837", "score": 0.7794635891914368, "text": "It's honestly more often than not just down to convention. For the same reason Europe is considered a seperate continent from Asia. There is no major physical barrier, at some points between Russia and Kazakhstan none at all even. Still the vast majority of people consider Europe seperate. There is no geographical reasoning behind this, it's mostly historical. Sorry to disappoint you, but there is no universally accepted metric to measure a peninsula. Some groups might have their own definitions, but those will vary between said groups.", "topk_rank": 1 }, { "id": "corpus-173143", "score": 0.7776906490325928, "text": "Cultural reasons. You could argue that Africa also belongs to the same continent, as it is actually connected to Asia by land so it is also part of that land mass. Humans just arbitrarily chose to separate them into different continents. Same reason Greenland is not it's own continent, but Australia is.", "topk_rank": 2 }, { "id": "corpus-166417", "score": 0.7749885320663452, "text": "The ancient Greeks first developed the idea of a continent. They saw that the Mediterranean divided Europe from Africa, the Red Sea divided African from Asia, and with their limited knowledge of geography, assumed the Black Sea divided Asia from Europe. They were wrong, but the notion stuck, and has been reinforced by a culture divide that runs roughly along the same lines.", "topk_rank": 3 }, { "id": "corpus-229443", "score": 0.7693474292755127, "text": "Broadly speaking, Asia can be defined as \"that part of Eurasia which is not Europe.\" There are common cultural and historical strands that run through most of Europe and remain conspicuous in modern Europe. There is no such thing in Asia. For a little test, think about how similar, culturally and historically, Spain and Russia are; then think about the similarities between Japan and Turkey. While the Sinai or Panama provide geographic reasons that Africa and the Americas are separate continents, the division of Eurasia into two are entirely artificial, and I find it very Eurocentric, to be frank. Sorry for this little rant. Anyways, my point is, Asia is enormous. Ancient Asia includes the Hittites, the Zhou, and everything in between. So is there any part of Asia you have in mind?", "topk_rank": 4 }, { "id": "corpus-125466", "score": 0.7669190168380737, "text": "[Absurdly relevant](_URL_1_) The main answer is because Europe is historically, culturally, ethnically, and linguistically distinct from Asia and the Middle East. It's not really about \"creating barriers\", that's just the way it's always been. [Here](_URL_0_) is a map from 2,400 years ago. Europe and Asia are separate.", "topk_rank": 5 }, { "id": "corpus-83257", "score": 0.7640079259872437, "text": "Because someone arbitrarily decided it's big enough to count as a continent and therefore not an island. The definition of a continent is arbitrary (at least under the general definition). They aren't defined in terms of plate tectonics, it's just that plate tectonics explains why there are big landmasses. Some tectonic plates aren't considered continents (e.g. the middle east isn't considered a continent) and Europe doesn't even have its own tectonic plate. There isn't a satisfying answer. The definitions of continents are so arbitrary that different countries don't even agree how many there are. For example many countries consider Europe and Asia to be a single continent (which to be fair makes more sense).", "topk_rank": 6 }, { "id": "corpus-1335556", "score": 0.7622650265693665, "text": "I know about the term Eurasia, but as far as i know it's \"officialy\" two seperate continents.", "topk_rank": 7 }, { "id": "corpus-165581", "score": 0.7616539597511292, "text": "History. It goes back to the Greeks, specifically a guy named Herodotus. He wrote that the world consisted of Europe, Asia and Libya (by which he meant Africa). Over the years, the idea of Europe as distinct from Asia was cemented by the existence of a honking great *nothing* separating the peoples of Europe from the peoples of Asia. This meant there was relatively little migration of either people or ideas between the two regions, reinforcing their distinctness.", "topk_rank": 8 }, { "id": "corpus-155835", "score": 0.7610967755317688, "text": "Because the civilization as you live in today started in Europe. America's is west of Europe. Asia is east of Europe. If you grew up in Asia then you would not have this conception. Europe is West. And America is just Americas", "topk_rank": 9 }, { "id": "corpus-65375", "score": 0.7574224472045898, "text": "It's a mish-mash of history, politics, geography and racism. People define Europe and Asia as separate informally but the truth is even till today there is no definitive answer to what exactly constitutes a continent. I'll leave it to the wonderful Mr Grey to explain: _URL_0_", "topk_rank": 10 }, { "id": "corpus-211852", "score": 0.7528619766235352, "text": "The question of where Europe ends and Asia begins is relevant, because there's not really a border there. The Ottoman Empire obviously had territory on both sides of the Dardanelles, the one place that Asia and Europe are actually separated. The Ottoman Empire was European to the extent that the other European powers treated it that way. But it wasn't Christian, so it was definitely very different. Russia... there's not an easy answer to this. Western Russia is obviously in Europe, and most of the population is in Western Russia, so it's European. Plus all the other cultural things. Christianity, the Habsburgs, etc. Russo-Japanese war? No. It's definitely an Asian conflict. It's probably best to treat Russia's Asian territories as some kind of colonial system. TL;DR if it takes place in Europe, it's European. If it takes place outside of Europe but involves European powers, it's probably colonial.", "topk_rank": 11 }, { "id": "corpus-234475", "score": 0.7459735870361328, "text": "The distinction goes as far back as ancient Greece, who saw a separation between Greece and the lands to the northwest, and Anatolia and the lands to the southeast. They either didn't know or didn't care what was further north of the Strait of Kerch, and simply assumed there was some sort of waterway dividing the two. This is a reproduction of a Greek map from some time shortly after [600 BCE](_URL_0_). And this is a map based on that one from about [200 years later.](_URL_1_) As you can see, while they did eventually explore the area to find that there was no such separation, the idea that Europe was distinct from Asia was useful and stuck around because Russia at the time was full of uncilivized tribes and the Greeks didn't give a crap about them. Interestingly, they thought of the Nile as the line between Africa (Libya) and Asia, not the Red Sea, which they were only vaguely aware of.", "topk_rank": 12 }, { "id": "corpus-127380", "score": 0.7428520321846008, "text": "Because it was named by Europeans. From the European perspective, the 'Far East' (China, etc.) is as far East as you can go without running into the ocean. So the 'Near East' would be when you stop being in Europe and are now in the 'East' and the 'Middle East' would be between those two points (although, in reality, the Middle and Near East are much closer than the Middle East and Far East).", "topk_rank": 13 }, { "id": "corpus-193559", "score": 0.7420983910560608, "text": "Jared Diamond attempted to explain this in Guns, Germs and Steel (which I highly recommend as a book). Essentially, if you look at a map of Europe, you will see it has a very irregular coastline with lots of peninsulas and islands. This means that ethnic differences are amplified as people are isolated from one another (Spain and Italy had large numbers of non-Indo-European ethnic groups well into the early days of the Roman Empire), and so are much harder to unite under the rule of one group of people. East Asia, however, has a very round and regular coastline, with the exception of Korea and Japan which maintain independence to this day, and Taiwan which only became Chinese during the 17th Century, and so it was easier to unite different disparate ethnic groups into one country.", "topk_rank": 14 }, { "id": "corpus-166433", "score": 0.7405679225921631, "text": "Look up the CGPGrey video on continents. Basically how continents are divided is arbitrary.", "topk_rank": 15 }, { "id": "corpus-719070", "score": 0.7377720475196838, "text": "This is probably a really dumb question. I didn't get a very good education and something I always struggle with is geography. When I look at a map of Europe]( I see middle eastern countries like Iran, Iraq, Saudi Arabia, Syria, etc. But when I look at a [map of Asia I see those same countries too. Aren't Europe and Asia separate continents? What is the meaning of the term \"middle east\", and on what continent is it? How can it be on both?\n\nAgain, this is a stupid question, but I'd appreciate if anyone can sort this out for me. I've searched around online and I only see confusing and conflicting information\n\nThank you!", "topk_rank": 16 }, { "id": "corpus-19", "score": 0.737228274345398, "text": "While not universally true (especially in the case of Europe who gets to be called its own continent for purely cultural/political reasons) A continent is considered to be the primary landmass on its tectonic plate. If you look at a map of tectonic plates: _URL_0_ You can clearly see that with a few notable exceptions such as Europe and India. In general continents occupy their own tectonic plate. So then if you are a landmass that is part of a continent's tectonic plate but is not connected by land to that continent, than you would be an island. Although even this is a fairly tenuous definition.", "topk_rank": 17 }, { "id": "corpus-298403", "score": 0.734321117401123, "text": "The continent definition is the tricky thing here, as they were identified histroically by mapmakers based on simple groupings of land which could be visually divided up into chunks. Continent definitions these days are little better, but can be based on discrete tectonic plate units, or areas of isolated continental shelf (although the definitions of continents have not advanced with our knowledge of tectonics). Ultimately, however, the original continent definitions were eyeballed by mapmakers long before we understood the underlying reasons for separate landmasses. Islands are defined as landmasses surrounded by water which are part of a larger continent. Australia is *not* an island - it is a continent. Greenland is an island because it shares a tectonic basis with North America. _URL_0_ _URL_1_", "topk_rank": 18 }, { "id": "corpus-175624", "score": 0.7329620122909546, "text": "I am not a native English speaker and as far as I know, continent means two things in English, while my language has different words for the two things. Continent means a land mass as well as large area of world. There's 7 of both, but America is composed of North and South American land masses/plates (plus more), while Eurasia is a land mass (the Eurasian plate) composed of Europe And Asia divided at the Ural mountains for maps and politics, most likely due to historically Europeans not venturing too far too often.", "topk_rank": 19 } ]

[ { "id": "corpus-325345", "score": 0.6848196387290955, "text": "We have many different types of memory. In this case the important distinction is between episodic and procedural memory. The first is the memory of stuff we personally experienced, the later is on how you do stuff. This division is rather handy as it allows you to ride a bike without thinking about all the times you fell down as a kid, learning how to ride a bike. Anyhow these types of memories are independent and can be damaged separately. One interesting case is patients with anterograde amnesia, that is they remember everything up to the accident but they can't form new long term episodic memories, just like in Memento. They can still acquire new skills. There has been a case there as an experiment a patient like this learned to play chess, and developed a certain level of skill in it, but still had no memory of actually playing." } ]

[ { "id": "corpus-1998303", "score": 0.6504362225532532, "text": "Over the last few weeks, I convinced my parents to see a speech doctor (I don’t know exactly what it’s called. I’m 15, come on.) and got professionally diagnosed with Non Fluent Aphasia. For those who are not aware, this speech disorder affects the speech and comprehension of speech of a person. I can only speak about 7 words at a time in a sentence, or a little more if you give me enough time. I don’t know exactly how I got it, however, it could be from a car accident that I experienced that injured my head a lot. Again, I don’t know. It’s been affecting my life for as long as I can remember.", "topk_rank": 0 }, { "id": "corpus-153611", "score": 0.6504108905792236, "text": "Sometimes they do. Very advanced Alzheimers patients can't walk, speak or sometimes even chew.", "topk_rank": 1 }, { "id": "corpus-1971397", "score": 0.6503230929374695, "text": "drug memories add to the effect of tolerance so psychological tolerance, physical tolerance, mental tolerance, and whatever other forms of tolerance exist all come together to form the final face value tolerance you experience in day to day life. \n\nall i know about amnesia is honestly a brief summary from psychology in high school and from movies where the plot surrounds re-gaining skills / languages / or even other memories ( which is over hyped without a doubt ) but my thought experiment has to do with drugs right now. would smoking weed after getting amnesia feel like the first time ever smoking if you hadn't smoked for years but you had been a heavy pothead using weed in many forms for days on ends to months to years? imagine snorting a line of some ketamine and feel a weird sense / feeling in your mind as you don't remember taking bumps from times long ago ? \n\nmaybe the nature of this entire post is too variable and lacks more concrete knowledge behind its backing but nonetheless, its pretty fucking fun to simply think about. does drug usage lie in the \"skill\" section as in with languages or tennis skills learned over the years? does drug usage lie in the \"memory\" section as in with tripping lsd with a best friend in the best environment being placed strongly as a good positive memory next to the ones from childhood hugging your mother? \n\nedit: furthermore, it is fucking boggling to think about the brain. i was just imagining how these \"memories\" get imprinted in the physical brain itself. absolute chaos.", "topk_rank": 2 }, { "id": "corpus-1256601", "score": 0.6501922011375427, "text": "So I have a congenital neurological illness. From 2 months old to 7 years old I had 5 surgeries (including one emergency life threatening one) and countless medical examinations on the regular. I was declared miraculously healthy at the age of 10 even though my disorder normally can't be cured at all, they just maintain it by surgeries even in adulthood usually. I am one of the very few lucky stories. As I remember I was a very happy and resilient child regardless and I don't think (or didn't think until now?) that I had suffered any trauma or had PTSD because of any of these things. My T thinks that my present problems are somehow related to my childhood illness, but I didn't really understand how that can be and thought that must be such a cliche psychological thing haha... Then I realized something today.\n\nI have almost no memory of these events as I was too young. But I have a distinct memory of the last surgery at 7 years old which was a very easy, short and routine one. I clearly remember how I was pushed on the gurney and how the nurses inserted around 5 needles in my arms on the way. I remember thinking to myself that I shouldn't cry even though it was a little bit scary. At the surgery room I remember my doctor talking to me. She asked me to talk so they can test if the anesthesia was working. I remember making jokes about how the gas tastes like chocolate before falling asleep (it did, they have tasty ones for kids I guess?). I remember doing this so I will be praised. And I *was* actually praised days later by the nurses for being brave. They told me how most if not all kids cry when they go to surgery, but I didn't. I thrived when doctors and nurses praised me. I craved their attention and encouragement. I just found my medical documents from back then and a clinical psychologist evaluated me at 6 to see if I am ready to school neurologically and cognitively because my illness can sometimes cause brain defects (luckily I was mostly fine), and she wrote that I was a patient, very playful and respectful kid, but I needed HUGE amount of praises and reassurance that what am I doing and how am I playing (during the tests) is okay at all.\n\nNow, at 24, I am in therapy, mostly because I am very avoidant, a huge people pleaser, emotionally closed off, touch averse and anxious which causes me to have relationship and attachment problems. (Some of it can be directly a side effect of my illness, since it affects the brain, but sometimes kids have more symptoms if they have medical PTSD due to the surgeries). This presents itself with my relationship with my T. Even though I have a fear of my therapist, I still want him to think that I am doing well and that I am hard-working. I try not to make ANY \"mistakes\" or cause problems for him. I am always beyond punctual, very respectful, never miss sessions, never get angry at him, give him the price in cash exactly so he doesn't have to search for any change, crack at least one joke per session about my problems to show him I am okay, but don't crack too many jokes, so he doesn't think that I use humor as a coping mechanism, I NEVER cry to not be awkward, I hide my emotions. I am just generally trying to be the \"perfect\" and resilient client... just like when I was 7 before my 5th surgery? And probably even before I have memories.\n\nNow that I realized this I feel so many things and feel so nervous about my childhood for some reason and don't know what to do. I don't know if I am right about this at all. And I don't really know what to do with this parallel. My medical condition may not be related to this at all. But regardless I logically know I should tell my T this, but that also means that I would have to admit that I am trying to please him, then I will have to cry, and I cringe so hard at both of these thoughts.", "topk_rank": 3 }, { "id": "corpus-1257420", "score": 0.650180995464325, "text": "I just found out I have aphantasia and I feel devastated. My whole life I thought things like \"picture in your head\" were figures of speech, and now I feel like yet another part of me is broken! What I'm curious about is if many other people with this condition have histories of trauma and/or mental illness. I have abusive parents and was diagnosed with depression and anxiety when I was 6, and I still have it to this day. The reason I'm wondering if this is connected to aphantasia is because I've always dissociated when under stress, and my mind goes totally blank. Could this unconscious \"blocking out\" be the reason why some people develop aphantasia? (I can't really remember if I ever didn't have it, so it could also just be something you're born with but I just can't help but wonder...) I've also been on antidepressants/anti-anxiety meds for most of my life so I wonder if that could have some sort of effect too. I'm trying to come off them for the first time since I was 13 so I wonder if anything will change.\n\n\nAnyways I'd really like to know if anybody else here has a similar experience to me. I know there isn't much research on the subject so I'd like to try and piece things together through everybody's shared experiences or something. Part of me is just throwing this out there to feel less alone so any input is welcome! Thank you guys for teaching me more about myself and letting me see that even though I'm weird there are still others experiencing the same things.", "topk_rank": 4 }, { "id": "corpus-1257651", "score": 0.6500469446182251, "text": "Even though we're most of the time not acting on our emotions, or even precisely because we aren't and so we aren't used to it happening, sometimes we are in agitated states like any other person, only to quickly go back to our normal emotionless selves, and maybe regret whatever we may have behaved like before.\n\nThis happens to me very much, and I was wondering how much is this an schizoid thing. So that's just the question if want to answer.\n\nIn my case it can go from years long things, to even having deleted usernames, or left places without even looking back, ashamed of keeping being in a place after having behaved and shown myself in such fashion. Sometimes it's a matter of respect for other people, too.\n\n---\n\nThinking about it beforehand, there're a few aspects to observe to this behavior. The first one (1) is, as mentioned, that we aren't used to be minimally emotion driven even, so whenever we do something as normal people would, we think we may have reacted too much, when in fact we could have just behaved as normal. Then we would be regretting —if we do, which we may not— something that isn't even accounted for the majority of the people, something that they'd tell you 'don't worry it was nothing', if we asked.\n\nAnother one (2) is how, because we're so unused to freaking out, we may in fact react in very disproportionate ways, sometimes letting i.e. anger after years of not letting a single spark of it, so the consequences may then be bigger and everything in point 1 wouldn't work.\n\nA third one (3) is how we perceive ourselves, and how much it affects us to perceive ourselves in an altered state.\n\nFinally, there would be thinking about how to behave when this happens.\n\nShare thoughts.", "topk_rank": 5 }, { "id": "corpus-1246040", "score": 0.6499702334403992, "text": "We've had a patient who just came back to us that is in her 70s and she has Alzheimer's. She has trouble remembering she's at the hospital and remembering that she called her children. She's also afraid that her children are out for her money. She'll sometimes think she's at home or if she tries to wander off, she'll think she's at the airport or that we're trying to kidnap her. The only way we can calm her down is if we call her children and getting her to the phone is a challenge, and a lot of times, her kids will ignore our calls or ask us to stop calling them.\n\nSo what I'm asking is that, when she gets argumentative and \"aggressive,\" what is the healthiest solution? We try and let her cool down herself and will walk with her and try and influence her to go back to her room if she wanders off. The only times we've gotten defensive with her is when she's tried to go into other people's rooms.\n\nShe kind of randomly goes off and we just take it as it goes. Any other tips you can give would be awesome.\n\nThanks in advance!\n\nI'm willing to go into more detail if needed. I kind of just ran some stuff off the top of my head.", "topk_rank": 6 }, { "id": "corpus-1743066", "score": 0.6498104333877563, "text": "Hi im back again, another question. Its also gonna end up being another vent and ramble but any advice helps.\n\nI have ptsd from repeated intense instances of trauma in my childhood, and I’ve already talked to my dr about how my memory about it was affected because of how many times it happened.\n\nHowever there is one specific memory not at all related to that main trauma that just stops at a certain point.\n\nTl;Dr: Is it possible to just have complete memory loss of specific trauma, or does that mean nothing traumatic actually happened?\n\nTW for possible CSA and INCEST//\n\nIt was the last thanksgiving we had at my grandmas house and I was like 12, 13? Anyway there was a 19yo cousin there who was making sexual comments and shit at me and at one point i was playing a video game with my younger brother that evening in the basement and he came down and sat next to me and put his arm around me while telling my brother to leave and give us space. But thats all I remember.\n\nI don’t remember anything at all of the rest of the night, not going home, not my family, nothing. I don’t know if anything happened or not. I don’t know if my brother stayed down there (he was adamant on not leaving through the time I have the memory) and i dont know if anything traumatic actually happened or Im just assuming the worst.\n\nThe only thing i know is that the memory causes horrible panic attacks whenever I come across a trigger. I havent brought it up with my therapist because I dont know for sure if anything actually happened and i dont want to waste her time.", "topk_rank": 7 }, { "id": "corpus-1033922", "score": 0.6497842669487, "text": "In pretty much every movie with a brain wipe, the only thing people remember is how to talk. No recollection of where they are, where they are from, or even their name. Enlighten me, Reddit.", "topk_rank": 8 }, { "id": "corpus-513591", "score": 0.6497637629508972, "text": "I've looked all over for mention but found nothing.\n\nDoes anyone forget everything in an instant and have to sort of reboot themselves? Like, your brain just shuts on and off and you don't know what's going on.\n\nI describe it like, you're writing on a whiteboard and the writing is your thoughts. \n\nYou turn to look at your writing and it's gone. And then you're like 'White board? Writing? Was I writing?? Where am I???? WHAT'S GOING ON?!\"\n\nFew days ago, I picked up some water to drink and forgot everything and I was sitting there, holding it, wondering whose water it was and where I got it from. But then I remembered it was my water.\n\nThinking back, I remember knowing everything and then forgetting and then knowing again. Very confusing.\n\nToday, I was writing in a book, looked up and realized I was at work and couldn't remember how I got here for a few minutes.\n\nDoes this happen to anyone else? My doctor doesn't believe me.", "topk_rank": 9 }, { "id": "corpus-1757044", "score": 0.6497604250907898, "text": "I have suffered from anxiety as a 11-12 year old and recently got of the meds that helped me calm it for about 3 years. I’m diagnosed with depression and add and I have yk, problems. The thing is after I switched meds everything turned upside down even more. My anxiety is back and worse than ever. No matter how much I sleep, if I’m home, if I’m with friends or at school I feel the same. And what’s scary is I can’t even explain it properly. Because I feel like I can’t think. Like I’m going dement or that I’ll just forget everything. This fuels itself as the stress severed the memory problem, which makes me more stressed and then it just spirals like that. I question everything; time, myself, people, words. It feels like everything is fake and that I somehow am alone in this hell. We’ve taken labs to check everything from blood sugar to kidney to b-12 and so on. Everything is perfect but I still have this feeling that I’m dying or forgetting 24/7. I get no rest from these thoughts and I’m terrified. Everyone tries to help me but it feels like they don’t understand, that I’m somehow smarter than the doctors or that I of all people will be the youngest person with e.g a stroke. What is wrong with me?", "topk_rank": 10 }, { "id": "corpus-320436", "score": 0.6497583389282227, "text": "Yes. One of the most infamous and prominent case studies in understanding this is the case of a young abused girl named 'Genie,' who was largely kept immobile up until I think her teen years, strapped to a chair by her father, and never spoken to. As a consequence of her abuse, she never learned to speak language. If you want to understand how the brain works without language, the best way to do that is seek out isolation studies. The wikipedia article for Genie goes into great detail about the case, and related findings, see here: _URL_0_ Of course the big problem is figuring out what developmental deficiencies are a result of Genie's lack of language, were already present prior to her abuse, or were a result of other abuse she endured. This is a problem with most similar studies as well.", "topk_rank": 11 }, { "id": "corpus-1719850", "score": 0.6496474742889404, "text": "It wasn't until recently (past 2-3 years) that I realized that I was a narcissist growing up, and I've been trying my very hardest to uproot that unhealthy framework in favor of something healthier. The problem is that it was my everything... it framed everything I knew and now that I'm pretty quickly tearing it down, it's like there's a complete loss of identity.\n\nIt's like that's all I was and now I'm up a creek without a paddle. Like I'm going too fast for my brain to catch up with. I also have a chronic problem with disassociation related to my narcissism, so it makes the effects felt by the loss of identity even worse. I completely cease to be a person aware of my surroundings and stop recognizing people are other human beings (they become faceless and unrelatable.) \n\nI have hiccups and the nature of recovery from these things dictate it's just going to happen again, but you want to diminish the frequency in which it happens until it becomes a non-issue. My problem is I don't know what to do when it DOES happen, it's like my whole framework for recovery crumbles and I experience amnesia.\n\nI'm just really disoriented. By the time I started writing this, I was already fully in the throes of a panic attack and by now, I'm a little calmer. \n\nCan any one relate or give me some tips on how to manage these things before I feel it fully hitting me/while it's happening?", "topk_rank": 12 }, { "id": "corpus-181105", "score": 0.6495792865753174, "text": "The part of your brain that processes language is... asleep. The part which stores memories is also mostly not working. The brain can't learn when it isn't doing those things.", "topk_rank": 13 }, { "id": "corpus-1743431", "score": 0.6495568752288818, "text": "About 13 years ago I checked myself into a mental hospital because I thought I was going insane and I had to do terrible things to myself until I died. Images of ritual abuse and torture had been popping up in my mind for years, and I dismissed them.\n\nI was diagnosed with DDNOS, later changed to DID, as a result of repeated traumatic abuse. I did the same thing I did before; dismissed the alters as just brain circuits that got separated out because of some vague bad shit in my childhood that no longer affected me.\n\nThat kind of worked for about 10 years, but then the alters became more intrusive. I had a breakdown when I realized I have more Inside People than I realized. With names I didn't give them, and with memories I didn't have. The bad shit was still affecting me.\n\nI found a good therapist, and we are working through things.\n\nOne thing that \"I\" was shocked to discover is that I don't think I'm the same person that was born. Many people say alters formed to protect the core identity. I was forced to dissociate and create an alter out of my core identity by my abusers. So my original \"self\" became two separate selves.\n\nBut they kept making me split, depending on what they wanted to use me for.\n\nI don't know who I am anymore. Seriously.\n\nI'm pretty co-conscious with everybody inside. In the current lingo, I'm the ANP (Apparently Normal Person) but I think that just means we have a common daily life \"memory pool\" that everybody connects to. There are two of me that handle my career; there are two or three that handle my daily life outside of my career. Then there are many many others with their own memories and jobs.\n\nI don't know who I am.\nWe don't know who we are.\nI don't even know if I'm real, when I get down to it.\n\nFuck it. This is really hard to explain.\nI'm not even sure what the point of this post was supposed to be.", "topk_rank": 14 }, { "id": "corpus-1719506", "score": 0.6495557427406311, "text": "I am a transgender man who was violently disowned by my family in late July. \n\nI have been getting therapy to help find new coping techniques, but I had to miss therapy this week due to being stuck in government offices all day to update my ID and social security card to reflect my new name and gender.\n\nBut I think that was a mistake, because this morning, all of my ongoing problems have started happening at the same time. Inability to make decisions, agitation, disorientation, memory loss, and another one I can’t remember, are all making it very hard to navigate to where I need to go this morning. Oh fuck, yeah, I can’t understand what people are saying sometimes.\n\nNo one has officially told me that I have PTSD, but I do know that I am suffering from the after-effects of trauma and I heard from my doctor that some of the symptoms I have are a result of that trauma.\n\nAnyway, I guess I’m here to ask if you have any suggestions on how I should handle this. I’m getting frustrated :/", "topk_rank": 15 }, { "id": "corpus-2531701", "score": 0.6494651436805725, "text": "Why does losing critical objects happen repeatedly and if I cant find them quickly, why does it fuck everything up?\n\nWhen I cant find something, I hate myself, I remember why I was suicidal, I remember why I stayed so fucked up for so long, and I'm a simple idiot--i mean who loses literally everything they touch, all day and every day. I fuck it all up--just like old times. It's like I'm 17, drunk, and just pissed tf of at me. I want to punch. I want to throw. I want to growl (still growl a bit).\n\nBut when I have everything, I'm not exactly happy, but I dont fly into that rage. I dont hate as hard and as thoroughly. \n\nTherapist say I need to be nice to me. I cant think of a good reason why.\n\nIf it helps explain things at all, I'm comorbid adhd-i, PTSD, and panic disorder. I take a host of antidepressants and bipolar medications as well as everyone's favorite (except me) ADHD medication. I've take these medications daily for 2 years.", "topk_rank": 16 }, { "id": "corpus-98013", "score": 0.6494325399398804, "text": "It's called infantile amnesia. The brain structures most associated with memory are still underdeveloped until around 4 years of age.", "topk_rank": 17 }, { "id": "corpus-2435334", "score": 0.6493871808052063, "text": "A few years ago, I had an ECT treatment that changed my life. I became disabled. The psychiatrist continually dismissed my neurocognitive symptoms for years and altogether stopped properly caring of me. \n\nMy new psychiatrist has called some of my previous doctor’s methods dangerous, especially in regards to medication. I was on lithium for way too long. I had too many ECT treatments. There were dangerous increases in medication dosages that were harming me more than hurting me. \n\nAfter talking with my new doctor extensively about my memory, focus, and concentration issues that appeared after that last treatment and my experience trying to get support for it, he diagnosed me with Treatment-Induced Neurocognitive Disorder. He acknowledges (and will be acknowledged for disability) that ECT caused these debilitating symptoms. I felt happy that my experience was finally being heard and there was a name for all the difficulties I face every single day. I wasn’t just a failure. But, when I search for more info, there’s so much info for drug and alcohol induced disorders which doesn’t apply to my situation. The general consensus is still that ECT is safe despite the risks, so I just can’t seem to find anything to help. The success stories, especially in studies, often overshadow stories of loss and grief. I feel like a forgotten statistic. I hoped this diagnosis would be the door to get more help or to find others like me. \n\nI know ECT has helped many and for them it was worth it. I’m glad for that. I truly am. But, I could never recommend it to anyone. Not after watching everything I’ve lost and fighting so hard just to have a somewhat functional life. I’m so crushed right now. I’ll be okay, I know that. I am still pushing forward. I’m just really disappointed and I’m not ready to take the next step at the moment. \n\nThank you for reading this. I wish you all wellness and happiness.", "topk_rank": 18 }, { "id": "corpus-294803", "score": 0.6493744254112244, "text": "Blacked-out people are not in a sleep-like state. They are concious, in the normal sense of the word, just not forming memories.", "topk_rank": 19 } ]

[ { "id": "corpus-325346", "score": 0.6581152677536011, "text": "Our Milky Way can be imagined like a plate, with us sitting about 2/3 away from the Galactic center. Looking towards the center the density of stars is high (although we do know some galaxies in that direction as well). These stars in the plane form the band of the Milky Way that you can see during dark nights outside of cities. Perpendicular to the galaxy the number of stars along a line of sight is much less and there's no problem at all to look outside. Also, do not forget that the density of stars is very low and that even our Milky Way is very empty - in practice it is dust and gas between stars that is more of a problem for looking far than stars themselves. A good model for the stellar density in our neighborhood is if you shrink the Sun to the size of a typical apple. If our Sun was in Manhattan, the next star, i.e., the next apple, would be in Denver." } ]

[ { "id": "corpus-314506", "score": 0.6250914931297302, "text": "The [center of the galaxy](_URL_0_) is in the direction of the constellation Sagittarius. There's a bit too many stars for me to see which part of the sky this is, it's hard to pick out the significant constellations.", "topk_rank": 0 }, { "id": "corpus-285742", "score": 0.6249745488166809, "text": "Unless lights bounces off of something for you to see it, you don't see it. Think about all the light passing between distant stars out there. We don't see any of that light, because it doesn't reflect off of anything. Sometimes, there are clouds of gas and dust like nebulae that we *do* see, where light has scattered off of that material and toward us.", "topk_rank": 1 }, { "id": "corpus-12566", "score": 0.6248583793640137, "text": "The super short answer is we don’t know. All we know is that the universe is getting less dense, and there is more empty space between celestial objects. Its also not doing so radially (from a center), but more just sort of in all directions. We know this through observation and measurement so we are sure its happening, we just havent worked out why. The common explanation is “dark matter/energy”. Which basically means energy/matter that we can’t see that just mathematically must be there in order for the expansion (and the masses of several galaxies) to make any sense.", "topk_rank": 2 }, { "id": "corpus-834513", "score": 0.624703049659729, "text": "Sorry for the terrible title, but I really don't have a short way to ask my question.\n\nFrom what I understand about astronomy(which is very little), the wavelength/color is used to determine a number of things about distant objects. Things such as temperature, moving towards/away from us, and what kind of material the light has passed through. So how do astronomers know that the light from a star is blue because it is hot and not because it is moving towards us?\n\nEDIT: Thanks for the replies! That really helped me out =D", "topk_rank": 3 }, { "id": "corpus-643867", "score": 0.6245529651641846, "text": "How is it that we can get these fantastically detailed pictures of nebula, galaxies, and star clusters - but we can't get super detailed close up photos of our own planets in our solar system? Just something I've always wondered and figured had something to do with how the photo stitching process works perhaps, but would love to hear an educated answer.", "topk_rank": 4 }, { "id": "corpus-306106", "score": 0.6245259046554565, "text": "Yes, there are places where it's that dark. In fact, most of the universe is that dark. If you were to suddenly appear somewhere else at a random place in the universe the odds are you would be in a place so dark you could not see any stars or galaxies. You could see galaxies if you had a telescope but with the naked eye there would be nothing to see, not even a dim glow, because the space between galaxies is so great. It makes you realize how big the universe really is.", "topk_rank": 5 }, { "id": "corpus-53857", "score": 0.6245214343070984, "text": "We can roughly estimate the mass of galaxies by seeing how many stars are shining. We can also roughly estimate the mass of galaxies by seeing how they rotate. The problem is, the second estimate is *much* larger. Thus, the difference must be made up by some kind of matter which is not radiating light... or in other words, dark matter. The expansion of the universe is accelerating, and this requires some sort of energy intrinsic in space to drive it. We don't know what this intrinsic energy is, so we call it \"dark energy\".", "topk_rank": 6 }, { "id": "corpus-322171", "score": 0.6245086789131165, "text": "We can actually say what the frequency of the broadcasted light was. The spectrum of starlight doesn't consist of a single frequency, nor is it constant and continuous. It has peaks and valleys at different frequencies. The locations of these depend on the material. We know that hydrogen absorbs light at very specific frequencies, so any light passing through a concentration of hydrogen will show a dip at those frequencies, because part of the light with those frequencies was absorbed by the hydrogen. Now, we know that stars are made of mostly hydrogen and helium, so we can predict what the spectrum of a star looks like. When the light gets redshifted, the gaps in the spectrum get redshifted along with it. By identifying the frequencies of things like hydrogen absorption lines in the redshifted spectrum, we can determine exactly how much the light was redshifted.", "topk_rank": 7 }, { "id": "corpus-303371", "score": 0.6244285702705383, "text": "When you say spiraling I assume you mean the galaxy is spinning. The reason galaxies are flat\"ish\" is because rotating bodies in 3D space form discs due to complex angular momentum interactions in the material. Galaxies can have 3D arms during something like a galactic collision since you have outside mass and angular momentum to mix up this process. Over time however, it will reform a disc.", "topk_rank": 8 }, { "id": "corpus-312008", "score": 0.6244077682495117, "text": "A great benefit in being part of a galaxy (in my own opinion) is that we are able to see other stars. Otherwise the only thing that we would be able to clearly view would be our sun, the moon and the planets. That may lead to an entirely different species-wide philosophy regarding our place in the universe.", "topk_rank": 9 }, { "id": "corpus-296312", "score": 0.6243939399719238, "text": "The highest redshift photons we can observe are those from the cosmic microwave background. Higher redshift photons cannot be observed because before the last scattering event -- when the CMB photons were able to freely propagate -- the universe was \"opaque\" to photons, i.e. photons were not able to travel without scattering. There were no stars and galaxies to emit photons, so we can't observe light from those objects with a redshift greater than the CMB. However, in principle, as the universe ages, objects which cross the cosmic horizon will appear to us to emit light which is asymptotically approaching z=infinity. Rather than disappearing, they will become dimmer and dimmer, not unlike infalling observers for a Schwarzschild black hole.", "topk_rank": 10 }, { "id": "corpus-260914", "score": 0.6243574619293213, "text": "Stars and dust. Lots and lots of stars and dust. It's estimated that there are about 100 stars per cubic parsec in the galactic core, wich is 100x more than in our neighborhood. The central cubic parsec around Sag A* has about [10 million stars on its own](_URL_0_).", "topk_rank": 11 }, { "id": "corpus-316459", "score": 0.6243389844894409, "text": "I originally misread your question, so my first response was wrong. The Sun orbits our galaxy about every 240 million years. It takes light about 100 *thousand* years to get across the galaxy. So the farthest stars have barely moved in comparison to the galaxy when the light makes it to the closet edge to us. I don't think it actually matters how close or how far away we are from the galaxy - I think adamsolomon might have misread it too (it's kinda hard to understand what you're asking). The tiny amount that the far stars will shift relative to closer stars should be the same no matter the distance. The only difference is in the *size* of the image we get - the larger the image, the more you can tell that stars shift (just think of it with pixels. The stars will move across more pixels if we blow the image up.) But the actual amount of distortion overall will be the same.", "topk_rank": 12 }, { "id": "corpus-297698", "score": 0.6243093609809875, "text": "There isn't anything particularly special about 2012. But the Sun isn't a very good lens anyway - it's too small and too close, so you only notice lensing very close to its surface. There are three types of lensing we can see: 1) Microlensing. Two star systems line up, and the one in the background looks way brighter for a day or so. The pattern of how quickly it gets brighter can tell us about the star systems. 2) Strong lensing: A distant galaxy cluster warps and magnifies stuff behind it. We see weird arc-shaped galaxies. These things are so far away that they don't appear to be moving, so these shapes don't appear to change. 3) Weak lensing: Like strong lensing, but weaker :) The distant galaxies aren't strongly warped, but if you perform statistics on them you can see they *tend* to bend one way more than the other, and that can tell you about how much gravity is in the lens - they actually used this for the Bullet Cluster. Hope that helps!", "topk_rank": 13 }, { "id": "corpus-128420", "score": 0.6242818236351013, "text": "a picture of a black hole would be a void of light. a black circle in a sea of stars is still \"visible\". Most detection of them is through their gravitational effects on nearby objects.", "topk_rank": 14 }, { "id": "corpus-266754", "score": 0.6242524981498718, "text": "No. The further we look away, the further we look back in time. The furthest we can see is the cosmic microwave background radiation. It's how the Universe looked like 400,000 years after the Big Bang. It was very young and galaxies, stars, planets, and so on, didn't exist at the time. We can't look further than that because behind the CMB the Universe is so young, and so hot, that it is ionized. It is opaque to light. Unless we manage to see the neutrino background or primordial gravitational waves, that's it, so it's like an effective edge of the observable Universe. At the very edge of the observable Universe is the Big Bang itself.", "topk_rank": 15 }, { "id": "corpus-285788", "score": 0.6242173314094543, "text": "No. Low-mass stars have lifetimes of trillions of years. So all galaxies will continue producing light for trillions of years, since low-mass stars are the most common.", "topk_rank": 16 }, { "id": "corpus-833102", "score": 0.6241995692253113, "text": "I would imagine with the vast amount of stars smashing into each other that there would be some sort of incredible explosion. is it just too bright to see? or is it actually common and i just haven't seen any proof? or do they smash together so fast that they merge together and create something more dense?", "topk_rank": 17 }, { "id": "corpus-325463", "score": 0.6241546869277954, "text": "Yes, but not by very much. The the closer part of the galaxy is a more recent image of what's going on in that particular region of Andromeda, while the far side is an older one. This gives a slightly skewed or warped perception of the state of the galaxy as a whole, but it's minimal and doesn't cause anything that would significantly impact our perception of Andromeda's shape, or its composition, distance, etc. Despite the differences being potentially hundreds of thousands of light-years depending on what points you choose to look at, it needs to be remembered just how enormous galaxies are, how far away they are from Earth, and how slowly they rotate from the perspective of a distant observer. Combine these factors, and you realize that the distortion of the entire image of Andromeda is negligible.", "topk_rank": 18 }, { "id": "corpus-324199", "score": 0.6241410970687866, "text": "Clockwise *is* anticlockwise if you look at it from the other side, which you can do with a galaxy. Therefore the question implies that there is a \"correct\" side to look at a galaxy from, which there isn't. The ones observable from earth have the appearance of being roughly half-and-half from our viewpoint.", "topk_rank": 19 } ]

[ { "id": "corpus-325347", "score": 0.7829383015632629, "text": "This is outside of my panel expertise, but I spent a summer working for a major consumer products company in their soap areas. The primary reason that consumer soap lathers (makes bubbles) is because consumers are conditioned to believe that if the soap doesn't lather, then it isn't cleaning anything. There are many commercial soaps that do not lather, like dishwasher soap, which is why you're always told to never put your sink dish soap in the dishwasher. The bubbles do serve the helpful purpose of letting you know where you haven't properly rinsed yet, and what parts of the dish you have cleaned. And yes, for dish washing soap you're intended to use by hand, bubbles are indicative of a higher local concentration of soap which by their very nature will tend to be at the surface of the water." } ]

[ { "id": "corpus-167507", "score": 0.73795086145401, "text": "Because your dish soap is engineered to produce a lots of foam (like your shampoo or hand soap too) to give you the feeling that its doing its work. It would have the same effect without the foam. In the washing machine or dish washer you cannot see the process, thereore there is no need to let it produce a lot of foam, which would be counterproductive anyway because you would need a lot more water to flush out the remains of the foam.", "topk_rank": 0 }, { "id": "corpus-1254295", "score": 0.7367516160011292, "text": "Dish soap is actually pretty concentrated, so squirt some into either an old plastic container you can keep around the sink rim or just in a bow/pot that needs cleaning, add some warm water, and mix it up. You'll now have a soapy solution you can use to clean the rest of your dishes with and don't need to squirt any more than you really need on the sponge.", "topk_rank": 1 }, { "id": "corpus-312777", "score": 0.7348545789718628, "text": "It is a good indicator about how much soap is left to clean off your dishes. Soaps don't truly react with anything, but they do surround fats and oils and \"pull it off\" the dirty surfaces. So if the soap is being used to surround a glob of oil, it can't make foam (which is basically air surrounded by soap). Now the interesting part is that different soaps generate different amounts of foam. In terms of cleaning ability they may be very similar, but not similar in foaming ability. So most dish detergent contains stuff that makes a lot of foam so it looks very effective. On the other hand, car wash soap contains (or should contain) less foaming agent because who wants to spend the time and water removing all that foam.", "topk_rank": 2 }, { "id": "corpus-292122", "score": 0.7322713136672974, "text": "Wouldn't the soap suds embed bits of the food material and grease that you're trying to get rid of?", "topk_rank": 3 }, { "id": "corpus-255450", "score": 0.7297878265380859, "text": "This is a similar reason to the question I saw earlier \"why does shampoo not suds as much in dirty hair?\". The bubbles in your dishwater are stabilized by the soap, when the soap binds to the oils that are present on the steel wool (they are added to slow corrosion of the steel) they cannot stabilize the bubbles anymore and the bubbles pop.", "topk_rank": 4 }, { "id": "corpus-1254342", "score": 0.7183080315589905, "text": "Has this worked for some? I've seen several pieces of advice to use a dish soap solution and I am wondering its pros vs cons.", "topk_rank": 5 }, { "id": "corpus-1126227", "score": 0.7104308605194092, "text": "If you end up with a spare empty foaming hand soap dispenser, reuse it with dish soap. Fill halfway with water before filling the rest with dish soap. And voila, pre-foamed dish soap to put on the sponge! This also seems to cut down on dish soap usage without sacrificing dish soap efficacy.", "topk_rank": 6 }, { "id": "corpus-189884", "score": 0.708021342754364, "text": "Short answer is yes, because what causes it to lather up is usually the act of rubbing or intentional \"use\" of the soap. There is a process called saponification when a strong base mixes with fat it becomes \"soapy\". This is how early soaps are made: animal fat and ash. _URL_0_ Rubbing soap on the surface of whatever you're trying to clean forces the soap to pickup more fats and oil, consequentially causing a lather -- so yes, it would be better. A foaming soap dispenser (whatever its called) however, I think, is not necessarily better than one that simply drips; but for another reason, it can be more efficient and less wasteful as excess liquid soap don't drip on the floor or sink.", "topk_rank": 7 }, { "id": "corpus-134462", "score": 0.7061181664466858, "text": "Bubbles are a natural property of soapy water, but the bubbles don't do much for the actual cleaning. Many detergents do *not* naturally bubble (foam), but a foaming agent is added to the ingredients because consumers expect to see some foam to confirm that something is there.", "topk_rank": 8 }, { "id": "corpus-323943", "score": 0.7059832215309143, "text": "Most of the time not. The purpose of most soaps/degreasers is to form [micelles](_URL_0_) around fat, oil and dirt, so these tiny \"bubbles\" can \"dissolve\" and be carried away by water. The foaming is to give the consumer a good feeling about it, as they can see and feel it working. But the foaming does help spreading and holding the liquid in place, so it has a function in products like shaving cream, where the purpose is to keep the hair moist. Ever realized bread is a type of foam?", "topk_rank": 9 }, { "id": "corpus-1253824", "score": 0.7051399946212769, "text": "I know this is probably something my OCD is tormenting me over, but sometimes when I wash and immediately refill my dog's water dish, there are little soap bubbles on the surface. I make sure to rinse the bowl thoroughly, so I'm pretty sure it's a trace amount.\n\nI change dish soap brands regularly. Right now it's Palmolive.\n\nI have noticed this for a while, and I haven't seen any medical problems in her, except for coughing, which is normal for her anyway--she's been doing it since before I was washing her dog dish daily (back then, she would get it washed once a week if she was lucky), and the vet has told me that her cough is caused by a heart condition, which she is on medication for.\n\nIt's definitely not super soapy water, but I don't know how much more thoroughly I can wash her dish to get every possible hint of soap out. Do you think she's okay?", "topk_rank": 10 }, { "id": "corpus-1252869", "score": 0.7034261226654053, "text": "I have no idea where to post this on Reddit so I guess this is the closest place I can think of. So very short story is my wife and I live with my parents. As is normally the case my mom rules the roost when it comes to cleaning. And we've been having a problem for years now and are fed up with it. \n\nWhen we moved into this new house we got a new diswasher (couldn't bring the old one). Well my mom has a bad habit of overfilling the dishwasher. So most of the time there is soap scum (the white marks all over). A picture(s) below show a microwavble dish that just came out of the washer. Mind you this dish is only a month old and has NO stains and is normally clean as a whistle. But this is what it looks like because of soap scum. My mom says thats normal and packing it with so much is \"normal\".\n\nSo my questions are:\n1. Are you suppose to cram the dishwasher with that many things?\n2. If you stuff it, doesn't soap scum appear?\n3. Is the soap scum we drink/eat thats on the dishes after bad for your health?\n4. If so, what issues can it cause?\n\nI should point out when I put away the dishes I obviously rinse any of them that have soap scum on them. Which I realize is stupid since the dishwasher should be what cleans them. \n\nHere are 3 pictures of the recent dish that came out (the one in front of screen is to show you that you can't even see through it):\n\n\n\n\n", "topk_rank": 11 }, { "id": "corpus-283277", "score": 0.7008746862411499, "text": "soap has the added benefit of emulsifying oils and other leftover, not so water soluble food elements. If you want to not leave dishes greasy you need to have enough soap to effectively emulsify and remove oils. other than that water does a pretty reasonable job with cleaning, especially at high temperatures.", "topk_rank": 12 }, { "id": "corpus-41090", "score": 0.7002180218696594, "text": "The foam is the result of air getting stuck in between thin layers of soapy water. Because the soap lowers the surface tension of the water, you need less pressure to make a bubble. When you make bubbles, you actually take soap molecules out of the bulk of the liquid, therefore lowering the concentration of your soapy water and making it less effective at cleaning. This is why industrial/commercial cleaners don't foam up so much. I would assume the point is marketing. If your detergents are soaping up, they look like they are doing something... however its actually worse for cleaning.", "topk_rank": 13 }, { "id": "corpus-1254138", "score": 0.6997553110122681, "text": "Weirdly enough, I can't seem to find a good response to this on Google; I just get articles about soap scum.\n\nWe use bar soap to wash our hands at the bathroom sink, but over time, the soap dish has become covered in super-hard, thick layers of dry, leftover soap. I've tried pulling it off with my fingers and soaking the entire dish in hot water for a while, but it doesn't seem to work. Does anybody have any advice for getting the dish clean?", "topk_rank": 14 }, { "id": "corpus-1254713", "score": 0.6995534896850586, "text": "All silliness aside.\n\nI will look at a plate or dish after washing it and inspect it and still miss things and they can still be dirty. So I changed the way I do the dishes.\n\nThis only works if you have a washing up bowl. It’s very simple and makes sense when you do it. Lift the washing up bowl out of the sink, when it’s full of water, put it next to the sink and then clean the dish you have, once cleaned take it out, and run the tap, cleaning the dish with water again. A simple rinse will usually show you anything missed\n\nIt works even better if you have a window where your sink is as you get more light on to the dishes.\n\nYou could say: why not wash the plate in the washing up bowl and then just pull it out the water, then rinse. Well, I can’t put my finger on the exact reason but you tend to focus more on it when you transfer it from the washing up bowl back to the sink. \n\nSo this might seem weird at first but give it try!", "topk_rank": 15 }, { "id": "corpus-272772", "score": 0.6994102597236633, "text": "[Adhesion.](_URL_0_) Water \"seems\" to stick to glass because it does. > I don't seem to notice this when washing dishes at home though. It certainly still does, but (a) possible you're looking at non-transparent dishes so you're not really noticing it, and (b) soap in the water will massively reduce the surface tension and reduce surface adhesion.", "topk_rank": 16 }, { "id": "corpus-324865", "score": 0.6983851790428162, "text": "Nope! Two soaps that don't foam are laundry detergent and the type of soap that goes in dishwashers. If you put a foaming type of soap in either of those machines, it will cause a huge mess. However, those soaps still clean dishes and clothes just fine. Lots of cosmetics companies actually add things (like sodium dodecyl sulfate or ammonium lauryl sulfate), to soaps to make them foam more, because many people associate foam with cleanliness.", "topk_rank": 17 }, { "id": "corpus-187517", "score": 0.6980319619178772, "text": "Dish soap has stronger detergents and more foaming agents (unless you're getting foaming hand soap). The stronger detergents break down grease better but also strip the oil out of your skin more.", "topk_rank": 18 }, { "id": "corpus-318220", "score": 0.6979498863220215, "text": "[Soap is an emulsifying agent](_URL_0_) and does most of the heavy lifting when cleaning - removal of food particles, grease, etc. [And you don't really need much more than that](_URL_1_). You could probably clean dishes with your hands as \"scrubbers\" and dish soap (I often do). While I'm on my soap box, I don't understand sponges. They're the perfect breeding ground for bacteria, remaining wet for ages. Those $3 plastic scrubber brush wand thingies scrub well, are simple to keep clean, dry quickly, and don't scratch dishes.", "topk_rank": 19 } ]

[ { "id": "corpus-325348", "score": 0.9223470091819763, "text": "No, soap bubbles are not necessary. As long as you have soap in water, it will do its job on dishes. However, bubbles are a helpful indicator that you have enough soap in your water, or that all the detergent molecules are not \"busy\" encapsulating grease." } ]

[ { "id": "corpus-309278", "score": 0.7825364470481873, "text": "The purpose of the soap is to help remove the things that are stuck to the plate and help the water wash away oils. If the plate is clean enough that the soap would have \"nothing to cling to\", whether that is true or not, would simply mean the dishes are already clean enough that the soap isn't necessary to clean that area. The majority of the work in the dishwasher is done by the force of the hot water spraying against the dishes.", "topk_rank": 0 }, { "id": "corpus-314876", "score": 0.7665472626686096, "text": "They don't. Foaming agents are added to soaps as a marketing strategy, as people erroneously believe that bubbles are more than just air pockets and actually have an effect on how clean things get. Bubbles can serve as a sort of indicator of the concentration of soap in the water, which does effect how clean stuff gets. However this is only a rough indicator, and isn't really reliable. Beyond that, there's really no correlation between bubbles and how clean anything gets. As an example compare dish soap and dishwasher detergent. Both are surfectants designed to do the same job. Dish soap has bubbles, thanks to the added foaming agents, and dishwasher detergent doesn't. Both get your dishes clean equally well (assuming correct use) proving that the bubbles really don't have any impact on cleanliness.", "topk_rank": 1 }, { "id": "corpus-325347", "score": 0.762660026550293, "text": "This is outside of my panel expertise, but I spent a summer working for a major consumer products company in their soap areas. The primary reason that consumer soap lathers (makes bubbles) is because consumers are conditioned to believe that if the soap doesn't lather, then it isn't cleaning anything. There are many commercial soaps that do not lather, like dishwasher soap, which is why you're always told to never put your sink dish soap in the dishwasher. The bubbles do serve the helpful purpose of letting you know where you haven't properly rinsed yet, and what parts of the dish you have cleaned. And yes, for dish washing soap you're intended to use by hand, bubbles are indicative of a higher local concentration of soap which by their very nature will tend to be at the surface of the water.", "topk_rank": 2 }, { "id": "corpus-1254295", "score": 0.7576411962509155, "text": "Dish soap is actually pretty concentrated, so squirt some into either an old plastic container you can keep around the sink rim or just in a bow/pot that needs cleaning, add some warm water, and mix it up. You'll now have a soapy solution you can use to clean the rest of your dishes with and don't need to squirt any more than you really need on the sponge.", "topk_rank": 3 }, { "id": "corpus-323065", "score": 0.7546653747558594, "text": "The fact is that soap is \"used up\" when it removes the various lipids from your dishes, so probably having less dishes will mean more soap to go around and therefore probably cleaner dishes. Probably cleaner, because the soap manufacturer may have already put enough to go around(although highly unlikely)", "topk_rank": 4 }, { "id": "corpus-64108", "score": 0.7515303492546082, "text": "Dish soap is made with \"bubbling agents\" which is different from dishwasher detergent. (And laundry detergent for that matter) so when you use it in the dishwasher, it bubbles up like crazy because it's supposed to make bubbles.", "topk_rank": 5 }, { "id": "corpus-167507", "score": 0.7496834993362427, "text": "Because your dish soap is engineered to produce a lots of foam (like your shampoo or hand soap too) to give you the feeling that its doing its work. It would have the same effect without the foam. In the washing machine or dish washer you cannot see the process, thereore there is no need to let it produce a lot of foam, which would be counterproductive anyway because you would need a lot more water to flush out the remains of the foam.", "topk_rank": 6 }, { "id": "corpus-318220", "score": 0.7456150650978088, "text": "[Soap is an emulsifying agent](_URL_0_) and does most of the heavy lifting when cleaning - removal of food particles, grease, etc. [And you don't really need much more than that](_URL_1_). You could probably clean dishes with your hands as \"scrubbers\" and dish soap (I often do). While I'm on my soap box, I don't understand sponges. They're the perfect breeding ground for bacteria, remaining wet for ages. Those $3 plastic scrubber brush wand thingies scrub well, are simple to keep clean, dry quickly, and don't scratch dishes.", "topk_rank": 7 }, { "id": "corpus-283277", "score": 0.7414439916610718, "text": "soap has the added benefit of emulsifying oils and other leftover, not so water soluble food elements. If you want to not leave dishes greasy you need to have enough soap to effectively emulsify and remove oils. other than that water does a pretty reasonable job with cleaning, especially at high temperatures.", "topk_rank": 8 }, { "id": "corpus-192362", "score": 0.738903284072876, "text": "This is a bit of a side note - soap does not need to be bubbly to be an effective cleaner. Things like dishwashers and front load washers use soaps that are low sudsing. The reason soap is effective is largely from the way it reduces the surface tension of the water. It does this because water is a very polar molecule - like little magnets that want to stick together. This is why water forms beads, and why you can fill a cup OVER the edge. The soap interferes with this polarity because it has one end that is like a magnet and one end that isnt. So it prevents the water molecules from sticking together. This is also what allows the water to encapsulate the dirt and oils and wash them away. Bubbles are optional. Some soaps are artificially made more bubbly by adding sugary substances. The 'stickiness' for lack of a better understanding allows the molecules to stick together in a way that nicely forms bubbles, but not in a way that significantly inhibits the cleaning action.", "topk_rank": 9 }, { "id": "corpus-312777", "score": 0.7369369268417358, "text": "It is a good indicator about how much soap is left to clean off your dishes. Soaps don't truly react with anything, but they do surround fats and oils and \"pull it off\" the dirty surfaces. So if the soap is being used to surround a glob of oil, it can't make foam (which is basically air surrounded by soap). Now the interesting part is that different soaps generate different amounts of foam. In terms of cleaning ability they may be very similar, but not similar in foaming ability. So most dish detergent contains stuff that makes a lot of foam so it looks very effective. On the other hand, car wash soap contains (or should contain) less foaming agent because who wants to spend the time and water removing all that foam.", "topk_rank": 10 }, { "id": "corpus-134462", "score": 0.7359110713005066, "text": "Bubbles are a natural property of soapy water, but the bubbles don't do much for the actual cleaning. Many detergents do *not* naturally bubble (foam), but a foaming agent is added to the ingredients because consumers expect to see some foam to confirm that something is there.", "topk_rank": 11 }, { "id": "corpus-255450", "score": 0.7357902526855469, "text": "This is a similar reason to the question I saw earlier \"why does shampoo not suds as much in dirty hair?\". The bubbles in your dishwater are stabilized by the soap, when the soap binds to the oils that are present on the steel wool (they are added to slow corrosion of the steel) they cannot stabilize the bubbles anymore and the bubbles pop.", "topk_rank": 12 }, { "id": "corpus-1254138", "score": 0.7349731922149658, "text": "Weirdly enough, I can't seem to find a good response to this on Google; I just get articles about soap scum.\n\nWe use bar soap to wash our hands at the bathroom sink, but over time, the soap dish has become covered in super-hard, thick layers of dry, leftover soap. I've tried pulling it off with my fingers and soaking the entire dish in hot water for a while, but it doesn't seem to work. Does anybody have any advice for getting the dish clean?", "topk_rank": 13 }, { "id": "corpus-324865", "score": 0.7347238659858704, "text": "Nope! Two soaps that don't foam are laundry detergent and the type of soap that goes in dishwashers. If you put a foaming type of soap in either of those machines, it will cause a huge mess. However, those soaps still clean dishes and clothes just fine. Lots of cosmetics companies actually add things (like sodium dodecyl sulfate or ammonium lauryl sulfate), to soaps to make them foam more, because many people associate foam with cleanliness.", "topk_rank": 14 }, { "id": "corpus-318689", "score": 0.7318291664123535, "text": "Realistically, not using soap is probably only going to outright harm you if you don't get all the oil of a dish (hard without surfactants) and it goes rancid. Otherwise food is easily scrubbed off of dishes, and harmful bacteria are unlikely to even be on the plates to begin with unless you used them for raw meat or they got cross contaminated with a cutting board.", "topk_rank": 15 }, { "id": "corpus-1253045", "score": 0.7302177548408508, "text": "I use an old windex bottle, it usually only requires one spritz per dish to get clean. This way your not putting gobs of soap onto your sponge and then losing most of it down the drain.", "topk_rank": 16 }, { "id": "corpus-187517", "score": 0.7275153398513794, "text": "Dish soap has stronger detergents and more foaming agents (unless you're getting foaming hand soap). The stronger detergents break down grease better but also strip the oil out of your skin more.", "topk_rank": 17 }, { "id": "corpus-117464", "score": 0.7272094488143921, "text": "Dish soap does not break down lipids; it binds them with water molecules to wash them away. It will also bind to any excess oil you have on your hands, which is why your hands will also come away clean after washing dishes, but your cell membranes are safe, since they are rather tightly attached to your body.", "topk_rank": 18 }, { "id": "corpus-1126227", "score": 0.7254906296730042, "text": "If you end up with a spare empty foaming hand soap dispenser, reuse it with dish soap. Fill halfway with water before filling the rest with dish soap. And voila, pre-foamed dish soap to put on the sponge! This also seems to cut down on dish soap usage without sacrificing dish soap efficacy.", "topk_rank": 19 } ]

[ { "id": "corpus-325349", "score": 0.6662116050720215, "text": "While I share your disdain, what selection pressure has been applied to their population? They don't itch until after they've flown away, so it's not like we stop the one that bit us from reproducing. And we haven't applied consistent measures against the several species over long enough times to have such a selection pressure." } ]

[ { "id": "corpus-259140", "score": 0.6328868269920349, "text": "Insects do not breathe via their mouthparts. They have holes on the sides of their bodies which are like tunnels leading into their bodies. This is a good starting point: _URL_0_", "topk_rank": 0 }, { "id": "corpus-306716", "score": 0.6328647136688232, "text": "Sure, why not. Why they haven't? They've got it pretty good already, survival wise. Insects are already some of the most \"highly evolved\" things out there, with some extremely sophisticated strategies in play. Evolution doesn't go \"forward\" to \"more intelligent\" species. Evolution goes towards what is immediately useful for survival.", "topk_rank": 1 }, { "id": "corpus-76916", "score": 0.63283771276474, "text": "Rhinos don't reproduce by the thousands, so mosquitos have that going for them. They're also tiny, and harder to hunt down. Insects have just about everything else on the planet beat when it comes to sheer numbers. We couldn't exterminate most insect species just because they breed in extreme numbers.", "topk_rank": 2 }, { "id": "corpus-61753", "score": 0.6327943205833435, "text": "Being a fucking nuisance mainly! But seriously though, I heard from somewhere else that flies like salt, hence why they are particularly fond of annoying people when they are hot and sweaty - all that salt water coming out of you is gold to them and they are trying to find a spot t land where they won't be swatted off before they can get anything. Our eyes and mouths also contain salt water substances too so that could explain why they always seem to go for these areas in particular (leaving me wishing I had the power to turn myself into a living bug-zapper so they're fried upon touching me)", "topk_rank": 3 }, { "id": "corpus-75420", "score": 0.6327007412910461, "text": "Some do - [lufenuron](_URL_0_) for example persists in the bloodstream and kills certain parasites which ingest it with stolen blood. It would probably work very nicely against headlice, but doesn't have a license for human use.", "topk_rank": 4 }, { "id": "corpus-301648", "score": 0.6326895356178284, "text": "Yes there have been several experiments that show mosquitoes can and do respond to other peers by altering their own wingbeat frequencies. This is mostly with regards to mating but there are other cases as well. Reference: Gibson, G., Warren, B., & Russel, I., J (2010). Humming in tune: sex and species recognition by mosquitoes on the wings. Journal of the Association for Research in Otolaryngology, 11(4), 527-540. There’s loads more recent evidence of this.", "topk_rank": 5 }, { "id": "corpus-312870", "score": 0.6326403021812439, "text": "While, as others here suggested, it's possible it serves a purpose, that's not required for evolution. A lot of people mistakenly thing something has to give you an advantage for it to be an evolutionary trait that is passed on, but in reality a trait just needs to not hinder your survival or reproduction to the point you are unable to pass it on. It's possible sickness is nothing more than the body poorly adapting to its internal changes but not so poorly that passing on that trait impossible. It may be our other traits allowed us to compensate for the sickness in a way that prevented it from being evolved out of us.", "topk_rank": 6 }, { "id": "corpus-276063", "score": 0.6325317621231079, "text": "> I suspect that Janet Fang's claim that “thousands of plant species” are pollinated by mosquitoes (Nature 466, 432–434; 2010) is an exaggeration. There are hardly any papers published on mosquitoes as pollinators, and only one plant species in North America — the orchid Platanthera obtusata — has been reported to be pollinated by these insects (J. R. Gorham Am. Midl. Nat. 95, 208–210;1976). > Given the mismatch between mosquito morphology and most flowers, it is likely that they are stealing nectar without acting as pollinators. _URL_0_", "topk_rank": 7 }, { "id": "corpus-313621", "score": 0.632226288318634, "text": "*Arbovirologist here. It wouldn't matter very much at all. Both male and female mosquitoes eat sugar from any source they can find (eg: rotten fruit, nectar, etc...), but only the females take blood meals. The protein in the blood is required to produce eggs, and would still be present in large amounts even if a person was hypoglycemic. I suppose the only thing that could possibly happen is that the mosquito would have to find another sugar meal more quickly than if there were an abundance of glucose in the blood.", "topk_rank": 8 }, { "id": "corpus-56563", "score": 0.6321414113044739, "text": "Two main reasons off the top of my head: 1. We don't know how to extermine only mosquitoes. 2. At best we can guesstimate what will happen to other animals due to mosquitoes dying off, but not much more. Historically, surgical attempts to mess with ecosystems haven't gone too well. Pesticides kill lots of pests, they get concentrated in bigger animals who eat those smaller pests. Remember DDT? It's rarely used now because it messed with the way large birds (bald eagle being the most recognizable) breed. Mosquitoes make up the a huge part of the biomass that feeds water animals (fish, insects and amphibians), both at the full grown stage and as larvae. I'm sure some insect would come to take its place, but in the meanwhile the ripple effect on the ecosystem would be enormous... introducing rabbits to Australia enormous.", "topk_rank": 9 }, { "id": "corpus-285935", "score": 0.632136344909668, "text": "Other species depend on mosquitoes. Spiders, frogs, etc. Good read [here](_URL_0_).", "topk_rank": 10 }, { "id": "corpus-15022", "score": 0.6320849657058716, "text": "There's all sorts of ways an organism can develop to fight parasites. Sickle-cell disease is suspected to be the result of humans adapting to resist malaria. Humans lost most of their hair because it gave parasites fewer places to hide.", "topk_rank": 11 }, { "id": "corpus-2364188", "score": 0.6320499777793884, "text": "An extract of mosquito saliva shot into the bloodstream, leaving you to itch everywhere at once would be horrible.", "topk_rank": 12 }, { "id": "corpus-180754", "score": 0.632020890712738, "text": "Because it itches. And the instinct is to scratch. Scratching an itching spot irritates the skin and releases natural painkillers that temporarily alleves the itching. But obviously, because the source of the itching tends to be things like a bug bite, it also spreads the poison and intensifies the itch.", "topk_rank": 13 }, { "id": "corpus-644286", "score": 0.6319964528083801, "text": "Or actually any mammal. I know that our biological systems are more complicated than most ‘simple’ organisms that do so, but then again, why can some vertebrates like zebrafish do it?\n\nWould love to hear some plausible explanations from an evolutionary standpoint.", "topk_rank": 14 }, { "id": "corpus-258489", "score": 0.6318647265434265, "text": "It is as simple as them having acid resistant outer skin layer. & #x200B; It is the same reason many other things are not digested, for example hair: It simply does not react with anything in the digestive tract. Just like hair, the outer skin of parasitic worms evolved not to react with their hosts digestive secretions.", "topk_rank": 15 }, { "id": "corpus-86204", "score": 0.631756067276001, "text": "When a mosquito bites you, their saliva gets under your skin. The saliva is an irritant and your body sends histamines (the same stuff released during an allergic reaction) to the site to alert you of it. Histamines cause itchiness, redness, swelling, etc.", "topk_rank": 16 }, { "id": "corpus-66602", "score": 0.6315836906433105, "text": "Former mosquito abatement worker here: Before a mosquito bites you it does what is known as \"probing\". It will probe around looking for the path of least resistance/good blood flow and in doing so can make it through some porous fabrics. A lot of mosquitoes don't have a proboscis long or strong enough to make it through a tight weave like denim. Most likely what happened is the mosquito was attracted to the scent of your feet (mosquitoes love stinky feet), and then flew up your trousers and bit you. A number of species stay about a foot off the ground then fly up when they detect heat/CO2 (your breath). [These fuckers](_URL_0_) are huge. This picture really doesn't do them justice though. They are primarily a livestock pest. I've been bitten through two layers of shirts by this hell spawn and the resulting itchy bump is a bitch. They can be an inch long and look like a big spider at a glance.", "topk_rank": 17 }, { "id": "corpus-55239", "score": 0.6315791010856628, "text": "This is akin to asking why we don't have a cure for mosquitos. After all, couldn't someone just analyze the smell and appearance of mosquitos, and then develop a micro robot that specifically targets them? The pathways you describe are active research pathways, so far as I know. But research is hard, and actually making the kinds of things you describe is even harder. Stem cells are simple conceptually, but actually making them do what you want safely and effectively is time consuming, expensive, and difficult. And, as in the mosquito example, you're dealing with living things that have defenses, exist in differing environments, and are really, really complex. Just because mosquitos, or Herpes, is common, doesn't necessarily mean its easy to develop the kinds of things your describing.", "topk_rank": 18 }, { "id": "corpus-251839", "score": 0.6314531564712524, "text": "It is actually an evolutionary advantage. Think of it like this: The process kick starts their little immune systems into getting into fighting shape by putting things in their mouths and exposing it to all kinds of bacteria and interesting micro organisms. You wouldn't want an immune system thats never had to fight a battle before, would you? We tend to think dirt, and being dirty is bad for us, but thats just not true 99.9% of the time. It actually has a ton of physiological benefits that we just don't really understand. source: _URL_0_; Edit: took out source pointing to the wrong article", "topk_rank": 19 } ]

[ { "id": "corpus-325350", "score": 0.7022450566291809, "text": "There are a couple theories for this so far. The simplest is basically that something crashed into it, and changed its spin the other way. We can't see the surface well enough to see any craters or such, so we can't confirm nor deny. EDIT: As pointed out below, we can see the surface. My bad. Another theory is that due to the density and mass of Venus's clouds, gravity may have caused a lot of rotational energy to be dissipated through tidal friction. This would have slowed down the planet and then the continued gravitational effects would have taken it to the equilibrium we see today. This theory is based on the fact that the length of 3 Venusian days and 3 Earth years have almost the same length, leading to a possible case of 3:2 tidal resonance. The Moon and the Earth are (I believe, please correct me if I'm wrong) 1:1 tidal resonance, which means 1 Moon day = 1 Earth month." } ]

[ { "id": "corpus-242955", "score": 0.6670729517936707, "text": "This is the same as our Moon. In the time it takes for the Moon to orbit around the Earth, it rotates once on its axis. Therefore, the same side always faces us. This is the result of [tidal locking](_URL_1_) (see the [image](_URL_3_), tidal locking is on the left side, the right side shows if the Moon weren't rotating at all relative to the Earth). /u/iorgfeflkd describes how common it is in one of the other big [threads](_URL_2_) at the moment and there's even another [post](_URL_0_) giving reference to how temperatures are distributed on an extrasolar planet.", "topk_rank": 0 }, { "id": "corpus-261889", "score": 0.6669031977653503, "text": "The Earth would have to spin the other way, or be turned upside down.", "topk_rank": 1 }, { "id": "corpus-35505", "score": 0.666504979133606, "text": "a few times a year, the planet mercury will appear to stop and move backwards. it's not actually doing so; it's just an illusion. figuratively speaking, people used to be extra cautious during this period in which mercury appeared to be in retrograde. in roman mythology, mercury was the god of business and communication, so it's easy to figure why people always were superstitious during this event.", "topk_rank": 2 }, { "id": "corpus-104167", "score": 0.6656103730201721, "text": "Because its rotation is sync'd up with its revolution around the Earth as you can see [here](_URL_0_). While the moon spins, it is also revolving around the Earth so that the same side is always facing us.", "topk_rank": 3 }, { "id": "corpus-342828", "score": 0.6652466654777527, "text": "I just noticed Europa, Nessus and Earth are spinning. The moon and the traveler are not... Is that new?", "topk_rank": 4 }, { "id": "corpus-308054", "score": 0.6650694012641907, "text": "Most of the bodies in the solar system orbit in roughly the same plane, with the same direction of motion and rotation: counterclockwise. Exceptions to this are Pluto, which has an eccentric orbit ~17° from the ecliptic (the plane of Earth's orbit), most other bodies are within a few degrees of the ecliptic although Mercury is ~7° off; Venus rotates clockwise instead of counterclockwise; and Uranus is \"tipped on its side\", with its axis of rotation closer to being parallel to its orbital plane rather than perpendicular to it.", "topk_rank": 5 }, { "id": "corpus-319215", "score": 0.6650532484054565, "text": "All planets and stars rotate because they are born through a process called Accretion. In the short, its because when a portion of a nebula collapses, it spins and the stars and planets that result will preserve that momentum. Here's a more in-depth explanation: _URL_0_", "topk_rank": 6 }, { "id": "corpus-42929", "score": 0.6650225520133972, "text": "The short answer is that nobody knows for sure. It might have been an asteroid hitting in just the right direction, slowing it down and reversing it. It might have been the atmosphere dragging it backwards. There are some [videos on the subject](_URL_0_) that you can check out.", "topk_rank": 7 }, { "id": "corpus-580864", "score": 0.6640190482139587, "text": "Tilted, as in spinning in the same axis relative to our Sun. Yet it's moons have the same axis as Uranus, so collisions did all that? Sounds unlikely.", "topk_rank": 8 }, { "id": "corpus-835098", "score": 0.6631941795349121, "text": "If it is, how can it maintain a constant velocity?\n\nIf not, does it oscillate around a certain velocity? \n\nIs it accelerating or decelerating? \n\nAnd from where does the spinning arise in the first place?", "topk_rank": 9 }, { "id": "corpus-168273", "score": 0.6628566384315491, "text": "Pictures are often simplifications used to explain hard concepts in easy ways. The planets aren't actually all in the same plane. But they're pretty close, because they all formed from the same gas cloud collapse that the Sun did, and everything in that cloud was roughly spinning the way the Sun does. The dust and rocks that were orbiting on other planes mostly crossed each other's paths, hit, and either fell into the Sun or got knocked into a more equatorial orbit. The reason not everything in the solar system spins the same way is for the same reason you can put backspin on a billiard ball. Angular momentum is conserved, but it doesn't have to be uniform. Some things can spin backwards if others spin forwards faster. As for why electrons are different, it's because they're following a different law of physics that uses a different equation. Solar system accretion obeys gravity, and electron orbitals obey electromagnetism. In S1, Electrons actually \"orbit\" in a sphere, not a circle!", "topk_rank": 10 }, { "id": "corpus-147305", "score": 0.6627655029296875, "text": "They don't reverse left/right **or** up/down. They reverse front/back. But because humans are bilaterally symmetrical, we look at the image and think \"how would I put myself in the same position as my image?\" and decide that the proper way to do that is to walk forward and then spin around on the vertical axis. But it's just as valid to say that you'd walk forward and then stand on your head, in which case it would seem like like the mirror reverses up/down.", "topk_rank": 11 }, { "id": "corpus-308181", "score": 0.6624942421913147, "text": "You talking about precession. Its basically a wobble in the rotation of a spinning object. It is unique to each rotating body. It is effected by the distribution of the mass and speed of rotation so each planets is different", "topk_rank": 12 }, { "id": "corpus-168634", "score": 0.6624273657798767, "text": "Imagine I throw a ball horizontally. It goes some way then falls to the ground. Now throw it harder. It goes further. Now throw it really hard. By the time it reaches the ground, the curvature of the Earth has moved the ground away a bit. Throw it fast enough and it might get half way round the world. Harder still and you'll hit yourself on the back of the head, assuming the atmosphere doesn't slow it down. The planets are like that. Going so fast sideways that they don't fall in.", "topk_rank": 13 }, { "id": "corpus-277387", "score": 0.6621792912483215, "text": "It is a result of collisions. If you have a cloud of objects in space that all randomly orbit one point (the common center of mass) then collisions will happen. If you take the orbits of the entire cloud and average them out, you will have a net spin in some direction, simply by chance, the overall spin being exactly zero is very unlikely. So, over time, collisions will result in all object orbiting in this average direction. Think about it this way: if all objects orbit the same plane and the same direction, no collisions happen. Anything not following this path will eventually collide with something else (given enough time) which changes their orbital paths. Over a very long timeframe this results in everything orbiting in the same plane, in the same direction. (Note that once bigger planets have formed \"collisions\" doesn't have to be actual physical collisions, but is also objects gravtiy interacting)", "topk_rank": 14 }, { "id": "corpus-165419", "score": 0.6620690822601318, "text": "The effect is because the poles travel less distance than the equator does. The stuff spinning is spinning (atmosphere) because the equator spins real fast and the poles do not. So it makes sense that they'd be a mirror image. They go from high speed spinning area, back, and \"down\" where down represents the lower energy (slower spinning) area. Does that make sense? So the stuff goes from \"equator\" to \"pole\" (and back) - its not because they're attracted to N or S, specifically, it's that it's more efficient to do that than cross over the equator.", "topk_rank": 15 }, { "id": "corpus-833335", "score": 0.6618865728378296, "text": "What would the amount of force to spin it be? Obviously it would be very very hard to do but is it possible? And would spinning it throw its rotation off. \nAssuming you could get it to spin, would the planet continue to spin or would it eventually overtime slow back down and become relocked?", "topk_rank": 16 }, { "id": "corpus-182000", "score": 0.6617187857627869, "text": "It spins counter to all other planets, as if it was hit by an object and spun the other direction like two pool balls.", "topk_rank": 17 }, { "id": "corpus-325027", "score": 0.6615003943443298, "text": "What iorgfeflkd is talking about is called \"precession\", all planets have it to some extent, and it is exactly what you're talking about.", "topk_rank": 18 }, { "id": "corpus-307457", "score": 0.6614629030227661, "text": "The reason celestial bodies orbit around each other is because of conservation of [angular momentum](_URL_0_). All solar systems start as very large clouds of gas which collapse under their own gravity. Unless that cloud has absolutely no initial rotation, as it collapses it will begin to spin faster. It's exactly the same as a figure skater doing a spin. When their arms/legs are spread out they spin slowly, but when they pull them in they start spinning much faster, even though they haven't done anything else.", "topk_rank": 19 } ]

[ { "id": "corpus-325351", "score": 0.7563555240631104, "text": "The bubbles that form rise into the slightly cooler water above them and quickly condense, collapsing with a 'click'. This happens many times a second with many collapsing water vapour bubbles, producing the roaring noise." } ]

[ { "id": "corpus-54536", "score": 0.7184067368507385, "text": "Mythbusters covered almost exactly this phenomena: _URL_0_ TL;DR: water heats to boiling, but does not have time to bubble until bumped, at which point it explodes(more or less)", "topk_rank": 0 }, { "id": "corpus-108952", "score": 0.7182565927505493, "text": "Water crossing obstacles like valves and restrictions. The water temporarily increases pressure and loses it fractions of a second later due to the [venturi effect](_URL_0_)causing a vibration you can hear.", "topk_rank": 1 }, { "id": "corpus-314836", "score": 0.7180687785148621, "text": "When you're cooking pasta, some of the starch and protein in the flour comes out into the cooking water. The surface tension of the water is increased by the addition of starch and protein from the pasta, so the bubbles formed by violent boiling don't burst as quickly, and the froth forms. As the froth forms, it develops an insulating layer that begins to trap heat in the water, making the boiling even more violent, which makes the froth more substantial, and this ends with a boil-over. The effect is amplified but not created by the lid, because the lid helps trap heat in the air above the boiling water, causing the violent boiling to begin earlier. You can still get boil-over in an open pot, but the heat from the burner needs to be higher.", "topk_rank": 2 }, { "id": "corpus-76800", "score": 0.7179393172264099, "text": "First of all, what you are seeing is actually liquid water droplets. Water in its gas form is invisible. If you boil the kettle, and look closely at the spout, you'll see a little gap between the kettle and the \"steam\". This gap is full of water in its true gas form. As it cools, it turns into visible water droplets, and this is what we see as steam. So why do you get more when you blow on a pan? Well, because when you blow, you are moving everything around, causing some of the water to get airborne, causing all of the steam to move around and cover a larger area, and also helping the invisible gas cool down into visible droplets as a result of it moving around.", "topk_rank": 3 }, { "id": "corpus-27745", "score": 0.7159737348556519, "text": "Even if the water is at the boiling point (100 degrees C or 212 degrees F) It still takes some more heat energy to get it to actually evaporate. This extra energy is called the \"heat of vaporization.\" The water near the bottom of the pot evaporates first, this is why the boiling bubbles start at the bottom and float to the top. Once the boiling water really gets going, a lot of the bubbles are forming and trying to get to the top, and this can push some of the water over the side. This water that gets pushed out over the top didn't get the heat of vaporization from the bottom of the pot yet, so it doesn't evaporate.", "topk_rank": 4 }, { "id": "corpus-276402", "score": 0.7143948674201965, "text": "Truthfully, shaking boiling water will cause it to boil slightly faster, due to the shock waves passing through it. The decreased pressure during rarefaction will speed up boiling at that point slightly. It's insignificant, though. The added energy from shaking is also negligible. > Also is that the reason the oceans don't freeze? Oceans don't freeze solid since ice floats. The surface freezes and forms an insulating barrier between the water and the overlying air. Sure, there is transference of energy through the ice, but as the ice thickens, this becomes quite slow.", "topk_rank": 5 }, { "id": "corpus-115706", "score": 0.7137858867645264, "text": "The very small bubbles you see when the water starts to warm up are dissolved gases like oxygen. As water heats up the amount of gas it can dissolve gets reduced, so some dissolved gases are forced out. In an electric kettle with an element on the bottom, or a pan on the stove, water is being heated from the bottom. Water is converted from a liquid to a gas throughout the liquid, but especially at the point of heating because the heat isn't distributed evenly throughout the water. The gas produced is much larger in volume and less dense than the surrounding liquid so it will rise and escape upwards.", "topk_rank": 6 }, { "id": "corpus-88443", "score": 0.7132075428962708, "text": "That 'roaring' sound is pretty close to [white noise](_URL_1_)(YouTube link to listen). [White noise](_URL_0_)(Wikipedia link for info) is what we call it when you have a noise that's made up of all the different frequencies/pitches of sound together (sort of like that brown you get when you mix all the crayons). I'm sure you know what that \"plop\" made when a drip of water drops into a larger bit of water. The pitch of that sound depends on how much water is dropping at a time. When you have a waterfall, you end up with millions and millions of drops from tiny \"blip\"s to giant \"blop\"s. Once you get enough of them together, you can't really tell them apart & you just end up with something that's pretty much white noise.", "topk_rank": 7 }, { "id": "corpus-266211", "score": 0.7130801677703857, "text": "It's called the [Schlieren Effect](_URL_0_). This occurs in water as well, as in hydrothermal vents when hot water is injected into the cold ambient environment.", "topk_rank": 8 }, { "id": "corpus-37823", "score": 0.7129064202308655, "text": "Water can happily exist in both liquid and gaseous form at 100ºC, and it takes a lot of energy to convert liquid water at 100ºC to an equivalent amount of steam at 100ºC (indeed, it takes more than 5 times as much energy as it would to raise that water from 0ºC to 100ºC). So when the water is boiling, it's staying at a stable temperature of 100ºC, and the energy being added is being used to convert small amounts of the water to steam. That's what the bubbles in the water are, the small amounts of water that have been converted to steam (at the bottom of the kettle, since that's where the heat source is) floating up out of the liquid water and escaping into the air.", "topk_rank": 9 }, { "id": "corpus-320568", "score": 0.7121937870979309, "text": "There's an important distinction to be made here about what boiling means, that is \"boiling\" is the process of water going from liquid to steam. So in a pot of 'boiling' water, the only water that is actually turning to steam is the water in contact with the hottest part of the pot, at the bottom where the pot contacts the element. You can see the bubbles of steam forming there as the boil begins. The rest of the water in the pot is still liquid, and thus not boiling, even though we would characterize the pot as being full of boiling water. When you stir the pot, the cooler liquid water is brought into contact with the bottom of the pot and cools it just a bit, enough that the boiling dies down until the bottom of the pot can heat the water up and cause it to flash into steam.", "topk_rank": 10 }, { "id": "corpus-303007", "score": 0.7113357186317444, "text": "The egg has irregularities on its surface that allow those first bubbles to form. And once they start forming, then the boiling continues. More technical: you are getting a little superheating in your water. The temperature of the water is over 212°F/100°C, but the gas bubbles (of steam) can't find a place to get started. It needs some irregular or rough surface to start forming bubbles. Your egg, a piece of dust, a scratch in your pan. Then once it does, watch out. Think about a glass of beer or champagne. There is always a string of bubbles coming up from one spot in the glass. It is the same principle but with the dissolved carbonation in the drink.", "topk_rank": 11 }, { "id": "corpus-309937", "score": 0.7104634046554565, "text": "Boiling and evaporation are different processes. Evaporation can happen at any time from the **surface** of the liquid, while boiling is a bulk process where all the liquid may turn to gas. This is why you get the bubbeling when boiling, as gas bubbles are formed below the surface and rise. Evaporation increases with higher temperatures because the energy in the liquid is randomly distributed between the water molequles, giving some of them high enough energy to evaporate from the surface. The reason there is so much steam when you shower is that the evaporation only happens from the surface of the liquid. Small droplets have a large surface area compared to the volume, so naturally this allows for a lot of evaporation.", "topk_rank": 12 }, { "id": "corpus-27097", "score": 0.7103683352470398, "text": "The ball is so hot that it is vaporizing the water around it creating an air pocket, at this point the area around the ball is so hot that the water is boiling into a gas before it even touches the ball. That pinging sound you hear happens when the air pocket cools down enough to collapse in certain places on the ball, and when liquid water comes in contact with or near enough to the ball it it quickly vaporizes and expands because the ball is still very hot. It does this a couple of times until the ball cools down enough to completely collapse the air pocket. Edit: Read up on the Leidenfrost Effect for more info.", "topk_rank": 13 }, { "id": "corpus-280446", "score": 0.7098804116249084, "text": "On the surface of any liquid, there will be a few molecules with more energy than the others, simply due to random jostling. If one gets jostled hard enough, it will leave the surface and evaporate. Boiling is a more extreme form of this process. The jostling is so intense that molecules _throughout_ the liquid, not just on the surface, have a chance to be jostled into high speed. If they're under the surface, they join with other fast-moving molecules to form a bubble, effectively creating a new surface for more boiling (homogeneous nucleation). Incidentally, the creation of a new bubble is helped if there is any speck or flaw in the vessel where fast-moving molecules can agglomerate. This is called heterogenous nucleation, and it's why tossing salt into a pot of boiling water will make it seem to boil more fiercely.", "topk_rank": 14 }, { "id": "corpus-1834019", "score": 0.709809422492981, "text": "Is it when little bubbles form? Is it when you get a few medium-sized bubbles floating to the top? Or is it when the pot is a raging inferno of watery fury?", "topk_rank": 15 }, { "id": "corpus-560820", "score": 0.7097997069358826, "text": "Pretty simple phenomenon that I noticed but can't figure out on my own. When I heat a pot of water and it comes to a rolling boil, if I take the lid off of it, very little steam rises from the pot. However, if I turn the heat off after the pot has reached a boil, then large amounts of steam come off when I take the lid off.\n\nSo, why does steam seem to develop more when I turn the heat off as opposed to when the heat is on?", "topk_rank": 16 }, { "id": "corpus-34968", "score": 0.7094337940216064, "text": "Boiling happens when water at the bottom of the pot is heated up enough to become steam. Since the heat source is at the bottom, the bottom is hottest (and the fastest to boil), and the temperature of the water higher up in the pot is cooler. When you stir the pot, the cooler water above mixes with the hotter water below, making most of the water an average temperature. Since the hottest water at the bottom is cooled down (compared to no stirring), it takes more energy/longer for the water to begin boiling.", "topk_rank": 17 }, { "id": "corpus-325002", "score": 0.7093263268470764, "text": "The other answers miss one small bit. The first bubbles that form when you heat up water is actually dissolved air. They form even before water reaches the boiling point because the solubility of gases decreases with increasing temperature.", "topk_rank": 18 }, { "id": "corpus-159476", "score": 0.7089321613311768, "text": "Sound is vibration. The act of water mixing with other water causes vibrations, and this makes a noise.", "topk_rank": 19 } ]

[ { "id": "corpus-325352", "score": 0.7417754530906677, "text": "This is a result of a phenomenon called cavitation. What happens is that the water that is in direct contact with the heating surface tends to become vapour (steam) and form little steam bubbles. But the moment these tiny bubbles are formed, being less dense than the water around them, they begin to rise in the water column. Very quickly they come into contact with water that is substantially cooler than 100 °C, and as a result the steam changes back into water and the bubble collapses, making a very tiny little bang. When many of tiny bubbles are doing this every second, we hear it as a kind of hiss or roar. Once the water is boiling, the sound stops because the entire water column is at 100 °C and so the bubbles can make it all the way to the surface and actually escape as steam." } ]

[ { "id": "corpus-561644", "score": 0.702240526676178, "text": "So physics wasn't my best subject but.. we all know that water has a boiling point of 100 C and it cannot exceed this temperature without changes in pressure. \n\nSo what's the point of simmering (besides reducing the risk of boiling your pot dry) or is that the only purpose? Barely boiling water is 100 C (right?) And rolling boiling water is still 100 C. Maybe not quite boiling is just under 100 C but does it really make a difference?\n\nContext: tried to make menudo and I can't tell if I overcooked or undercooked. I had been texture taste testing it for the last hour on the stove (3.5 hr total) and I'm leaning toward undercooked but those of you who've made it know that overcooking it will make it tough as well. Recipe calls for 2-3 h of cooking so I'm questioning my temperature control", "topk_rank": 0 }, { "id": "corpus-241483", "score": 0.7021213173866272, "text": "I would assume that heat energy from the bottom of the kettle is causing more rapid sublimation (vaporization) of the underside of the water drop. That in turn causes the remainder of the water-drop above (which is still in liquid form) to ride on a cushion of gas (water vapor), and move forward. Since the pot is circular, the moving water drop hits the side as it tries to move forward, and bounces off the side (again and again), and thus follows a circular path.", "topk_rank": 1 }, { "id": "corpus-320692", "score": 0.7012258768081665, "text": "So your ears are not deceiving you, hot and cold water sound different. It doesn't have to be resigned to landing in your sink, pouring a mug of cold water versus boiling hot water sounds remarkably different. In fact, I can tell my shower at home has heated up when the sound changes. Despite how fascinating this is, the answer is unfortunately rather mundane. The viscosity of water changes as the temperature of the water changes, and this results in the change to the sound. Viscosity is how thick or \"gloopy\" the water is, while water is not very viscous at all the viscosity still drops by a factor of 4 or 5 between 0C and 100C. This is because the van der waal's, intermolecular forces become comparatively weaker as the random thermal motion of the water becomes stronger. [Here is a chart of the viscosity (and density) of water changing as it is heated](_URL_0_)", "topk_rank": 2 }, { "id": "corpus-321845", "score": 0.7011520862579346, "text": "> Where do all the bubbles in water come from during boiling? When the water has reached a vigorous rolling boil, the bubbles coming up to the surface are made of water vapor. Water is undergoing a phase transition from liquid to gas at the bottom of your hot pot and forming little gaseous bubbles of water vapor. Those then float up to the surface and release water vapor in the air; you can actually see this water when it condenses into steam over your pot. Also, I remember hearing once that the bubbles that you begin to see on the side of the pot *before* the water reaches a full blown boil are not primarily water vapor, but are actually dissolved gasses that are separating out of the water. [Edit: Found a source for this one.](_URL_0_) > This is quite possibly the stupidest question I've ever asked. =/ The only stupid question is the one that goes unasked :)", "topk_rank": 3 }, { "id": "corpus-315711", "score": 0.7009332180023193, "text": "Microboiling. Long before the overall temperature of the water reaches its boiling point, the bottom of the kettle will have reached this temperature and produced bubbles that quickly flash into steam and collapse again when coming into contact with the cool(er) water around it. The sound of these bubbles collapsing can often be loud enough to make a pop or a sizzle, which is what I assume you mean.", "topk_rank": 4 }, { "id": "corpus-98844", "score": 0.7008444666862488, "text": "Normally, a water heater has a lot of piping. Pushing the water through this extra piping takes pressure away from the water. So the water is pushed out of the tap with less force, so the sounds it makes is different. In addition, heated water often has air bubbles in it. You can see this because they make the water slightly cloudy. Air bubbles absorb sound and allow the water/gas mix to compress or expand slightly. This also changes how the tap sounds.", "topk_rank": 5 }, { "id": "corpus-36800", "score": 0.7007834911346436, "text": "The metal is trying to shrink as it rapidly cools, which causes stress on the metal and makes that noise. You should let it cool a bit before immersing it in water...", "topk_rank": 6 }, { "id": "corpus-60892", "score": 0.7002276182174683, "text": "Water boils at a given temperature for a given pressure. If the pressure is reduced the temperature, or energy, needed to cause a boil is reduced. A vacuum would need very little. Try taking some really hot water that hasn't reached a boil yet, placing it in a glass tube with a plunger. If you pull on the plunger, you are increasing the volume and reducing the pressure. The almost boiling water may then being to boil. This is a great example to show students too. Look up ideal gas law. And this also comes in handy when sanitizing large glass carboys for homebrew using alittle hot water, a rubber stopper, and abit of bleach.", "topk_rank": 7 }, { "id": "corpus-321596", "score": 0.6998561024665833, "text": "The steam is just more visible. While actively boiling you are creating a lot of water vapor that is rapidly rising and moving away from the surface of the water. Holding your hand above will feel very hot and moving quickly. As soon as you remove the heat you stop the vigorous vapor production and the air above the water calms significantly. This lets that air cool down somewhat which condenses a lot of the water vapor that was there from boiling or still coming off the near-boiling water and allows you to see it much better.", "topk_rank": 8 }, { "id": "corpus-170032", "score": 0.6984056234359741, "text": "Two places. The tiny bubble you get before it starts really boiling are air bubbles. Air dissolves in the water, but as the water heats up, it can't hold as much air, so some of it will form bubbles as it leaves the water. Second, the bottom of the pan is the hottest, so the water on the bottom changes to a gas before any other water does. It forms bubbles that float to the surface.", "topk_rank": 9 }, { "id": "corpus-317862", "score": 0.6981664299964905, "text": "the water starts to boil at the bottom, as the small bubbles rise to the cooler water they collapse, similar to cavitation, very noisy. this transfers heat upwards more efficiently, bringing the entire kettle to the boiling point, the bubbles no longer collapse, so the sound diminishes and the chamber fills with steam, then the kettle whistles. source (ish): _URL_0_ background: Navy Nuclear Power operator.", "topk_rank": 10 }, { "id": "corpus-311851", "score": 0.6948191523551941, "text": "In the case of a pot on the stove close to boiling it's going to be bubbles of steam. As the water heats up there is a temperature gradient from the bottom of the pot (hotter) to the top (cooler) and that gradient is steepest right at the surface of the pot. When the water is hot enough some of the liquid will vaporize and bubbles will nucleate (begin to form) at imperfections in the surface of the pot. They'll grow and adhere to the bottom of the pot (surface tension) until their buoyancy lifts them off and you get bubbles moving up. Once the bubbles grow fast enough you'll get a lot of bubbles rising and the rate of convection (mixing) will increase. Around that time you'd say the pot is at a full boil.", "topk_rank": 11 }, { "id": "corpus-23809", "score": 0.694701611995697, "text": "When water is hot and boiling, the water molecules are moving really fast and when you throw it into the air they want to move away from each other. This creates more surface area and more places for the heated water to contact the cold air, thus freezing the water. If the water was cold it would stick together more and less area of the water is confronting the freezing air.", "topk_rank": 12 }, { "id": "corpus-90037", "score": 0.6945207118988037, "text": "That is water. Because the bottom of the pot is the closest to the heat source, the water at the bottom is heated first. When it reaches the boiling point, it turns into water vapor and floats to the top as a bubble.", "topk_rank": 13 }, { "id": "corpus-115706", "score": 0.6943972706794739, "text": "The very small bubbles you see when the water starts to warm up are dissolved gases like oxygen. As water heats up the amount of gas it can dissolve gets reduced, so some dissolved gases are forced out. In an electric kettle with an element on the bottom, or a pan on the stove, water is being heated from the bottom. Water is converted from a liquid to a gas throughout the liquid, but especially at the point of heating because the heat isn't distributed evenly throughout the water. The gas produced is much larger in volume and less dense than the surrounding liquid so it will rise and escape upwards.", "topk_rank": 14 }, { "id": "corpus-292816", "score": 0.692162275314331, "text": "An exceptionally smooth surface can cause a flash boil like your describing because there are no nucleation sites on the inside surface of the vessel to form vapor bubbles. The movement of the pot causes a sufficient motion of the water to generate a nucleation site and then it is a cascade reaction (think diet coke mentos) Another common experience is microwaving a coffee mug of water that is superheated but only flashboils when your tea or spoon touches the water. Typically people get burned, I hope you weren't injured.", "topk_rank": 15 }, { "id": "corpus-81308", "score": 0.6919195652008057, "text": "Your pipes are pressurized so gasses easily dissolve in the water. Overnight the gasses slowly \"boil\" out of the water since it's now under much lower pressure", "topk_rank": 16 }, { "id": "corpus-77572", "score": 0.6913886070251465, "text": "Most household water (especially tap water) isn't pure water. It has minerals and flouride and all other kinds of stuff dissolved in it. When you boil it, the water evaporates off but the solutes stay. If I had to guess, I'd say that's what makes the smoke. Just a guess, mind you. You haven't exactly given a lot to go on. It could just be some crud stuck to your pan.", "topk_rank": 17 }, { "id": "corpus-65038", "score": 0.6900471448898315, "text": "The \"exploding\" water is caused by something called superheating. When you bring a pot to boil on the stove, you first see the water begin to \"nucleate\"--tiny bubbles form on the bottom and sides of the pot and then rise to the surface--and then come to the familiar rolling boil. When you use a microwave, as the other poster said, you're heating the water all at once, rather than from the bottom. If you're using something like a ceramic mug, which is much smoother than a metal pot, the water can't nucleate and may get hotter than its boiling point without actually boiling--that's superheating. But as soon as you disturb the water by, say, moving it or putting a teabag in it, the water sort of remembers that it forgot to boil and does so all at once, sometimes quite violently.", "topk_rank": 18 }, { "id": "corpus-18371", "score": 0.689937949180603, "text": "The lower temperature causes the vapor to recondense into liquid and the bubbles collapse, making a noise. When the water is uniformly hot and the bubbles make it to the top gradually louder, as bubble production increases, until the water is so uniformly hot that the bubbles make it to the top without popping.", "topk_rank": 19 } ]

[ { "id": "corpus-325353", "score": 0.7040722370147705, "text": "It's the speed *through* space which is limited by 'c', not the speed of light itself. Imagine you're at an airport. The maximum speed that you can move with your heavy suitcase is 10 mph. Now, you get onto the moving walkway... you can walk at 20 mph, with the aid of the belt. Are you exceeding the 10 mph limit? No, because you're only *walking* at 10 mph... it's the ground that's carrying you along, and making your walking speed look faster than it is. This is how it is; moving walkway = expansion of the Universe. The Universe is just the floor that the galaxies move around on, but the floor moves." } ]

[ { "id": "corpus-18706", "score": 0.6688632369041443, "text": "A neutral observer would see one person traveling 0.7c in one direction and another person traveling 0.7c in the other direction, so in that reference frame the relative velocity between them would appear to be greater than c. This is fine, though, because the observer doesn't actually see either of them as moving faster than c and so no FTL travel is observed. In the reference frame of each traveler, we have to take into account that velocities don't add linearly; instead, each sees the other approaching at (0.7c + 0.7c)/(1 + 0.7\\*0.7) = 0.94c So again there is no FTL motion observed in those reference frames. Velocity never adds linearly, but it seems like it does because in ordinary circumstances the scaling factor is too slight to be noticeable. If both travelers were only moving at 300,000 meters per second (0.001c), they would see each other moving at (0.001c + 0.001c)/(1 + 0.001\\*0.001) = (0.002c)/(1.002) which is only a tiny amount below 600,000 m/s.", "topk_rank": 0 }, { "id": "corpus-168993", "score": 0.6688525080680847, "text": "If A is traveling at 0.5c and B is traveling at 0.6c ( c being the speed of light in vacuum ) in opposite directions: The relative velocity is not 1.1c. The problem with what you have done is that you do not add velocities directly when the speeds are relativistic. You use the relativistic addition formula which ensures everything stays smaller than the speed of light. s=(u+v)/(1+UV/c^2) In general, special relativity does not allow for special reference frames and so you can just sit (at rest) in a specific reference frame and describe the velocity of the second particle relative to the first (which is at rest) and you should see that in this case it is clear that the speed will not be greater than the speed of light to such an observer.", "topk_rank": 1 }, { "id": "corpus-2021058", "score": 0.6688169240951538, "text": "I mean, one train goes 5Km/h, the next one will be going +5Km/h faster... and so on and so on.. until you reach the speed of light. Is this possible?", "topk_rank": 2 }, { "id": "corpus-168976", "score": 0.6687116026878357, "text": "To put it in an ELI5 scope, we know how light dims and dissipates the further you are from the source. We then look for a star in the galaxy which we can accurately estimate the brightness of at the source, look at how bright it appears to us, and then use this data to determine how far away the star is. To use an analogy, it's like figuring out how far away a car is from how bright its headlights appear to you. You know how bright headlights are when you're right next to them, so you can tell how far away they are from how bright they appear to you at that distance.", "topk_rank": 3 }, { "id": "corpus-74132", "score": 0.6686519384384155, "text": "The best explanation of this that I've read is by Randal Munroe of [XKCD](_URL_1_). It is titled [The Space Doctor's Big Idea](_URL_0_) and describes Einstein's theory of general relativity in the 1000 most common words in English. The biggest thing I got from it was that in a universe where everything is relative to the velocity of something else, the speed of light doesn't change regardless of the compared \"fixed\" point.", "topk_rank": 4 }, { "id": "corpus-295301", "score": 0.6686264276504517, "text": "No. For several reasons, physics doesn't make a lot of sense \"from the perspective of light.\" As a physical observer *approached* the speed of light from our perspective, we too would *approach* the speed of light from theirs. But neither of us will ever see the other going *faster* than light (ignoring stuff like gravitation and the expansion of the universe)", "topk_rank": 5 }, { "id": "corpus-192667", "score": 0.6685342192649841, "text": "Eli5: Expansion can be thought of as caused by a weak force gently pulling things apart. Gravity is a force that pulls objects together. Gravity gets weaker as you head away from the mass creating it. Expansion gets stronger as you put more distance between you and another point. Where gravity is really weak, far from any mass the expansion is significant. This means neighboring galaxies will drift apart. However close to the Galaxy, the gravity pulling all the stars together is stronger and so it isn't pulled apart", "topk_rank": 6 }, { "id": "corpus-272473", "score": 0.6685285568237305, "text": "I assume you mean the object in the bottom left of [this image](_URL_0_)? That's a foreground star, which is very much brighter than the background galaxies. The sharp lines are known as [diffraction spikes](_URL_1_), and are an artefact caused by various bits of the telescope that are in the line of sight. You can see a few more stars in the top image in the article, and can just about make out some diffraction spikes for the brighter galaxies (I've never actually noticed them before!).", "topk_rank": 7 }, { "id": "corpus-288185", "score": 0.6684272289276123, "text": "Particles moving faster than light actually go backwards in time. They're called [tachyons](_URL_0_) if you'd like to do some reading, but physicists generally regard them as nonexistent because they break causality. And also, your math is a little rough, because when you use a velocity faster than light in the time dilation equation, you get an imaginary number. > t'=1√1-(2c/c)2 which in turn gives us t'=1/√1-(2)2 . Which in turn gives t' = 1/sqrt(-3) = -i / sqrt(3) is an imaginary number.", "topk_rank": 8 }, { "id": "corpus-303619", "score": 0.668424665927887, "text": "Reading through your comments I realize you have fundamentally misunderstood doppler- and/or cosmological redshifting. To simplify, imagine that the speed of light is 1 m/s. Now if a source is sending out light at a constant frequency of 1 Hz, that is one period per second, what will we observe? Well if the source is stationary we will see a wavelength of 1 meter, but what happens if the source isn't stationary? Well, between each peak in the period the light source will have moved a little bit, so the wavelength of the observed light will change accordingly. If the source is moving toward you the two peaks will be closer together so the wavelength has become shorter (blue) and if it's moving away from you the peaks will be further apart and the wavelength has become longer (red). The wave itself is still travelling at the same velocity, the speed of light.", "topk_rank": 9 }, { "id": "corpus-321395", "score": 0.6684129238128662, "text": "The expansion is most evident on extremely large scales. At smaller scales, it's practically undetectable. Everyday objects have EM interactions that utterly overwhelm the expansion. The planets aren't moving away from each other or the sun because they are *gravitationally bound*, so aren't affected by the expansion. Similarly, the sun is gravitationally bound to our galaxy, and the galaxy is gravitationally bound to nearby galaxies, like Andromeda. However, most of the galaxies we can observe are not, in fact, gravitationally bound to our galaxy, and are far more distant. The further up in scale you go, the more obvious expansion becomes. When you get to the scale of galactic superclusters, which are not gravitationally bound to one another, you see the expansion takes over and becomes dominant.", "topk_rank": 10 }, { "id": "corpus-86323", "score": 0.6683946847915649, "text": "As far as I know (and according to relativity) it's impossible to *approach* the speed of light but there isn't anything saying that something couldn't have come into existence going faster - we just haven't ever found anything and a lot of physicists think it may be impossible because it would violate causality (i.e., you could get information before it happened). But the reason why nothing can approach the speed of light is that the energy of an object with a given *rest mass* m (or, mass when it's not moving, because moving adds mass) and velocity v is equal to (m * c^2 ) / (sqrt (1 - (v^2 / c^2 )). If v = c, the term inside the square root is zero, which means you're dividing by zero, which means you have infinite/undefined/not-a-number energy. And that's impossible.", "topk_rank": 11 }, { "id": "corpus-298889", "score": 0.668367862701416, "text": "Yes. The cause is, as you say, redshift. Energy is not globally conserved in general relativity, only locally.", "topk_rank": 12 }, { "id": "corpus-306194", "score": 0.6683666706085205, "text": "Stars make up galaxies, so the answer is yes to both. Leaving the finer points of the impossibility of luminal or supraluminal travel aside, the depictions are also inaccurate insofar as all the light isn't compressed to a tiny blinding point of light and ultra hard radiation directly ahead in the direction of travel. Compare [this surprisingly inaccurate animation](_URL_0_) (coming from ESA, no less...) with [this more accurate depiction](_URL_2_) of what accelerating up close to c would look like. Now you know why Star Trek's Worf has such a [large cutaneous turd](_URL_1_) on his forehead, to block all that hard blueshifted radiation that's coming from straight ahead when Klingons travel the intergalactic voids. This part of Star Trek canon at least has the decency to appear somewhat based in speculative fact, not fiction (and I love Star Trek, for the record!).", "topk_rank": 13 }, { "id": "corpus-246419", "score": 0.6682087182998657, "text": "I don't think you need relativity. Non-relativistic Doppler effect alone tells you that the spectrum of the parts of the sun in front of the probe will be blue-shifted, and the spectrum of the parts behind it red-shifted. Both the Sun and nearby stars produce not only visible light, but also ultraviolet and infrared. If visible light is blue-shifted, infrared will be visible, and if it is red-shifted, ultraviolet will be visible. If you accelerate something to nearly light speed, cosmic microwave background radiation will be blue-shifted to gamma rays, and reacting with the protons in the probe produce pi-mesons, which will take energy away from the probe. The speed where it happens is called the GZK limit.", "topk_rank": 14 }, { "id": "corpus-833202", "score": 0.6681532859802246, "text": "Moving faster than light means you can't see the present, and the further something is, the older the image. My question is this: are there faster than light methods of telescopy? \n\nCan people see where they're going in the literal sense when going into warp, or is everything just calculated?", "topk_rank": 15 }, { "id": "corpus-310900", "score": 0.6680195927619934, "text": "Very high, actually. Galaxies might look kinda dense, but the stars are actually very far apart relative to their size, so the likelihood of two stars even coming close to each other during a galactic \"collision\" is very small. It will be chaotic on a galactic scale, yes, but at the scale of a single solar system it's very unlikely that you'll see any change other than the night sky looking different.", "topk_rank": 16 }, { "id": "corpus-261644", "score": 0.6679958701133728, "text": "The universe didn't start from one point exactly. The light we're seeing now is from an area of the universe that is now very very distant from here.", "topk_rank": 17 }, { "id": "corpus-79527", "score": 0.6679661273956299, "text": "Imagine a ball with spikes. Those spikes are rays of light. Every ray of light consists of photons. If you extend spikes, they won't hit everything in the room. But if there is nothing between us and a spike, spike will reach us. So if you speak about entire galaxies, at least something should hit us, but it's never guaranteed. It's like shooting bullets(photons) at very big rate in all directions.", "topk_rank": 18 }, { "id": "corpus-237825", "score": 0.6679559946060181, "text": "The constant rate of exponential expansion of space would not give rise to a \"big rip\". A big rip would require an *increasing* rate of exponential expansion. If that were the case – for example if the \"cosmological constant\" were increasing with time – fewer and fewer galactic clusters would be gravitationally bound, then the outer edges of galaxies would begin to evaporate away into the void. (It's one of those slightly silly theories that's fun to extrapolate until the expansion is big enough to rip planets apart and then rip electrons off atoms, but has no justification behind it at all.)", "topk_rank": 19 } ]

[ { "id": "corpus-325354", "score": 0.741911768913269, "text": "The nail plate is generated by proliferating cells at the proximal end of the plate called the matrix (sort of under the cuticle). As the new nail is added it is pushed out towards the tip of your finder. It is attached to the nail bed - which is like the epidermis under the nail plate. The nail bed cells also migrate out towards the finger tip along with the nail. At the end of the nail bed is the hyponychium that seals the free edge of the nail plate to prevent stuff from getting shoved under the nail plate. So basically the growing tissue, in multiple layers, is continually being produced and moves out. The only \"attachment\" is where the progenitor cells sit on a basement membrane over the dermis - all the movement is in differentiated cells in the newly generated tissue. edit: [diagrams and gross pics](_URL_0_)" } ]

[ { "id": "corpus-180259", "score": 0.7030969262123108, "text": "New cells are continually produced by cells in what is called the 'matrix.' As the new cells are made, they push the existing cells forward, resulting in the growth of the nail down the length of the digit. If you mean why as in \"what is the reason\" it counterbalances the normal erosion and damage that takes place over time to nails, maintaining them.", "topk_rank": 0 }, { "id": "corpus-168225", "score": 0.6999276876449585, "text": "They offer a great deal of protection to your fingertips for many activities. They allow you to scratch and pick at things that would be extremely difficult without a nail. I have no idea why they grow at different rates though.", "topk_rank": 1 }, { "id": "corpus-55033", "score": 0.6979655027389526, "text": "That's the *lunula*, and it's the visible part of the *matrix*, which is the growing part of the nail.", "topk_rank": 2 }, { "id": "corpus-45339", "score": 0.6965331435203552, "text": "It's from a dry nail bed. Most people over the age of 25 have them simply from washing their hands a lot throughout the day, which removes oils. Once the ridges are there the next bit of nail tends to grow with the same ridge pattern, so they don't really go away once you have them. They aren't Beau's Lines. which are horizontal depressions in the nail that might be caused by infection or injury.", "topk_rank": 3 }, { "id": "corpus-39801", "score": 0.6954532861709595, "text": "They are excess cuticles. Just an overgrowth of the cuticle, which protects your nail bed from getting dirt or debris in it.", "topk_rank": 4 }, { "id": "corpus-53380", "score": 0.6950699090957642, "text": "Fingernails are actually supposed to be translucent, that's why you can see the nail bed through them. They turn white after they grow out because they're no longer receiving any moisture from your body.", "topk_rank": 5 }, { "id": "corpus-902", "score": 0.6947984099388123, "text": "well first you should know that its normal. Evenly spaced vertical lines are never a sign of a problem (But horizontal lines, you should see a doctor.) What happens is that as you get older, parts of the nail matrix (the part of your fingers that the nail grows out of) atrophy. They become weak and dont function quite as well. This results in the increasingly prominent vertical ridges. They're very similar in this way to skin wrinkles. Just the natural result of the aging process.", "topk_rank": 6 }, { "id": "corpus-685797", "score": 0.6945925354957581, "text": "I definitely don't have clubbed nails, and I actually see my PCP pretty regularly, nearly monthly, so I doubt I have a serious disorder.\n\nBut, once my nails start growing past 1/8th inch, some start to curve downward enough to obscure the silhouette of my nails. It's obnoxious.\nThe only thing I've found, beside consulting my doctor, is trying to up my iron levels. \n\nAnyone else deal with this? What do you do about it?", "topk_rank": 7 }, { "id": "corpus-113692", "score": 0.6940977573394775, "text": "*We aren't sure.* Here are two good theories: 1. Blood circulation is better in the fingers, feeding nail growth. Compare this to your feet, which are given the short stick in regards to blood supply in the body. 2. \"Terminal trauma\" -- meaning the more you use a digit, the more your body assumes it needs to grow, because the nail is being worn down quickly.", "topk_rank": 8 }, { "id": "corpus-162525", "score": 0.6937122344970703, "text": "I think OP is talking about the nail bed. The cuticles are the \"skin\" joined from finger to nail. Are you talking about the white semi-circles that are still part of you nail OP?", "topk_rank": 9 }, { "id": "corpus-12410", "score": 0.6925182938575745, "text": "It does stretch and break, but the nail is moving slowly enough that the tiny injuries and repairs happen without you noticing. The growth occurs under the small patch of skin at the base of the nail. The rest isn't actually alive, it's just hard protein, similar to hair, working its way across the top of your finger. The nail bed (underneath the main visible part of the nail) constantly adjusts as it works its way out.", "topk_rank": 10 }, { "id": "corpus-117626", "score": 0.691896378993988, "text": "Because the cells in the nail bed that produce your fingernails aren't fast-reproducing cells. Hair grows at a rate of about 1.25 cm / month. Nails only grow at a rate of about 0.3 cm / month.", "topk_rank": 11 }, { "id": "corpus-187417", "score": 0.6908767819404602, "text": "A cat's claw - for example - does not grow like our fingernails. Our fingernails grow in layers horizontally, so to say. A cat's claw grows from 'inside out', basically. The sharp tip thus is always really sharp, as it's part of the 'youngest' structure of the nail. The outer sheaths of the claw grows duller over time so the cat scratches things to get rid of these sheaths. I have 2 cats and sometimes i find these near the scratching pole. They look a bit like fully grown cat claws but at a closer look they are thin and hollow.", "topk_rank": 12 }, { "id": "corpus-320219", "score": 0.6906212568283081, "text": "It's called [Leukonychia](_URL_0_). It typically results from a minor injury to the [nail matrix](_URL_1_). Usually, it is nothing to worry about.", "topk_rank": 13 }, { "id": "corpus-173745", "score": 0.6892693638801575, "text": "I think there are keratin producing cells at the base of your nail, under the cuticle, that which deposit keratin in one direction, like the ones that make hair. This pushes the nail across the nail bed, or the part underneath your nail. That lighter-darker look might be your nail-bed, but I’m not sure.", "topk_rank": 14 }, { "id": "corpus-180048", "score": 0.6885865330696106, "text": "Just under the skin behind your cuticles, you have your nail matrix. This is a group of cells whose only job is to secrete the protien keratin in a large sheet, then push the sheet forwards. At that thickness, keratin is basically colorless and translucent; while it's attached, you can see the nail bed through it (the pink), but once it's fee-hanging, the ambient light makes your nails look generally white (as long as you keep them clean).", "topk_rank": 15 }, { "id": "corpus-135115", "score": 0.688106119632721, "text": "It's not exactly that they grow even, they get polished by asperities and thus they acquire a smoother edge. That's also why we have fingernails in the first place, to take care of friction on behalf of our fingers.", "topk_rank": 16 }, { "id": "corpus-1237331", "score": 0.6880041360855103, "text": "For example, if a rock hits your nail bed. It eventually grows out with the rest of the nail, and isn’t painful.", "topk_rank": 17 }, { "id": "corpus-192918", "score": 0.6865746974945068, "text": "> ELI5: Why do the nails on my ring fingers grow faster than the other nails? You're weird Just kidding. Most of it has to do with blood circulation. Some people's fingernails grow at different rates. Some people find that different fingernails on one hand grow at different rates . Some people find that their fingernails on one hand grow at a faster rate than those on the other hand.", "topk_rank": 18 }, { "id": "corpus-53245", "score": 0.6859221458435059, "text": "..You mean what's sometime referred to as the \"Lunula\"? It's part of the root structure of the nail, as in the flesh that your nail grows out of, and it's appearance varies from person to person. It's perfectly normal to not have a visible lunula.", "topk_rank": 19 } ]

[ { "id": "corpus-325355", "score": 0.8375988602638245, "text": "The answer is that they don't slide, rather the whole nail bed and nail grows out together. In the same way that the skin of your inner ear (all the way to the outer ear canal) grows outward, but it's not as though it's \"sliding\" anywhere. If you could look at a slice of your finger and recognize individual cell types, you'd see that the cells of the nail bed grow up, and out. The whole process is naturally carried forward, but as a unit, not with a sliding motion. Does that make sense?" } ]

[ { "id": "corpus-311946", "score": 0.7574962973594666, "text": "Your nails are \"built\" that way on both sides, but during the months of time it takes for the nail to grow out, the top is constantly exposed, and essentially gets sanded down. The bottom is not, and is essentially adhered to the skin underneath the whole time.", "topk_rank": 0 }, { "id": "corpus-182490", "score": 0.7561197876930237, "text": "The skin under the nail plate grows with the nail, the same way your outer skin is shed as new skin grows, it just grows forward in direction like the nail", "topk_rank": 1 }, { "id": "corpus-322240", "score": 0.7559099793434143, "text": "Yes, they are atached to the skin under it. If you've ever lost a fingernail, you can see the skin underneath is frayed where it was loosely attached. It doesn't grow out painfully precisely because it is so slow.", "topk_rank": 2 }, { "id": "corpus-176303", "score": 0.7554324865341187, "text": "Our nail bed is a bit different than ordinary skin, and is basically a membrane which specifically clings to the bottom of our fingernail. When the nail bed ends and normal skin begins, the finger nail is able to grow away from the membrane.", "topk_rank": 3 }, { "id": "corpus-10998", "score": 0.7496861219406128, "text": "It's called the [lunula](_URL_0_ and it helps the nail retain its structure.", "topk_rank": 4 }, { "id": "corpus-325354", "score": 0.7454307675361633, "text": "The nail plate is generated by proliferating cells at the proximal end of the plate called the matrix (sort of under the cuticle). As the new nail is added it is pushed out towards the tip of your finder. It is attached to the nail bed - which is like the epidermis under the nail plate. The nail bed cells also migrate out towards the finger tip along with the nail. At the end of the nail bed is the hyponychium that seals the free edge of the nail plate to prevent stuff from getting shoved under the nail plate. So basically the growing tissue, in multiple layers, is continually being produced and moves out. The only \"attachment\" is where the progenitor cells sit on a basement membrane over the dermis - all the movement is in differentiated cells in the newly generated tissue. edit: [diagrams and gross pics](_URL_0_)", "topk_rank": 5 }, { "id": "corpus-77705", "score": 0.7453266978263855, "text": "Underneath the nail is living tissue, the *nail bed*. This tissue exists to support & hold the nail to the finger, and there's blood vessels, nerves, and collagen in there that doesn't want to be damaged. Deeper down at the base of the nail is the *nail matrix* which is the part that grows the nail itself, and deeper injuries can damage this as well.", "topk_rank": 6 }, { "id": "corpus-175490", "score": 0.7433424592018127, "text": "From what I understand (from my equine science degree) you have lamella on the under side of the fingernail and the outside of your finger closest to your nail. Imagine these are like Velcro and stick together to hold on place by interlocking. They are much stronger than what you would expect of Velcro and very sensitive so it if possible to rip them apart and also very painful. Any people reading this with long nails will appreciate the pain of accidentally pulling the nail backwards. Because the nail is not ‘fixed’ to the finger, as the nail grows slowly, the lamella almost reform to keep the attachment but allow for growth", "topk_rank": 7 }, { "id": "corpus-238998", "score": 0.7426817417144775, "text": "Humans have cuticles to protect the nail bed from bacteria. If the nail bed were to continuously grow bacteria due to a lack of protection, the nail would not grow properly.", "topk_rank": 8 }, { "id": "corpus-295984", "score": 0.7418400645256042, "text": "The nail plate (the outer fingernail) is believed to attach to the underlying nail bed via CEA adhesion protein, and together they move distally from the nail matrix (where the initial hard fingernail is formed) toward the end of the finger. Once the nail bed terminates its proximity to the nail plate at the hyponychium (the skin at the groove you described in your question), the nail plate no longer has CEA to attach to and continues its distal movement without any additional need for reattachment. See: Zaias N (2014) The Nail Bed, Part I. The Normal Nail Bed Matrix, Stem Cells, Distal Motion and Anatomy. J Dermatolog Clin Res 2(1): 1008.", "topk_rank": 9 }, { "id": "corpus-189461", "score": 0.738535463809967, "text": "No it isn‘t. It‘s like the nail is resting on the skin underneath. And when the nail is growing longer it’s some kind of „gliding“ over it. Had a work accident back in 2017 where i lost my nail from left middlefinger. So i could see this nail grow back from the scratch.", "topk_rank": 10 }, { "id": "corpus-171368", "score": 0.7360624670982361, "text": "Wood isn't rigid. It can be compressed slightly. If you compress it, it tends to expand back, like a spring or a piece of rubber. So, when the nail is inserted with force, the wood around it is compressed, and it presses back on the nail, holding it tight in there. If you pull out the nail, it won't slide back in easily, because the wood has expanded as you pulled it out. Other materials deform permanently, such as metals. Nailing a metal this was is not gonna work, because metal doesn't press back on the nail and doesn't hold it in place.", "topk_rank": 11 }, { "id": "corpus-135115", "score": 0.7358550429344177, "text": "It's not exactly that they grow even, they get polished by asperities and thus they acquire a smoother edge. That's also why we have fingernails in the first place, to take care of friction on behalf of our fingers.", "topk_rank": 12 }, { "id": "corpus-181090", "score": 0.7338354587554932, "text": "That's called the lunula. It's the visible part of the root of your nail. This is where the nail grows from.", "topk_rank": 13 }, { "id": "corpus-325135", "score": 0.728865921497345, "text": "Basically, the base of the growth is situated at the part of the nail that is closest to your wrist (when your fingers are extended). Your skin folds over itself at the base, forming a sinus - a cavity in the external body in this case. All the walls of this sinus are external surfaces of your skin. In the base of this sinus, an area of skin express a large amount of keratin. Because of the shape of the sinus, growth of keratin-rich young cells pushes older cells out across your finger. This pushing compress the growing cells into a dense matrix of dead cells and keratin. So, your fingernails are just dense, flattened, protein-rich skin-cells. Because they were pressed together like that they form a strong matrix of multiple layers. If you're asking why only cells on that part of your body grow this way, I'm not prepared to answer that.", "topk_rank": 14 }, { "id": "corpus-320407", "score": 0.7273216247558594, "text": "The fingernail helps the pad of the finger to maintain grip (it prevents it from rolling) so they still serve a function. They also represent the remnants of claws from our ancestors of course. Typically nails would not have grown terribly long in ancient times due to the large amount of manual labor the typical person would have been doing on a daily basis.", "topk_rank": 15 }, { "id": "corpus-60454", "score": 0.7272184491157532, "text": "The nail bed, like the rest of our skin, consists of the dermis (inner layer) and epidermis (outer layer). The epidermis of the nail bed moves with the nail plate, and is connected to the dermis by tiny longitudinal grooves called matrix crests, along which it also moves.", "topk_rank": 16 }, { "id": "corpus-175702", "score": 0.7265833020210266, "text": "See that region just behind where the nail is? Your nails start growing from there and then push forwards. Because the back part of your nail is a set width it can only be so wide. It can push forwards 'infinitely' meaning your nails can be 'infinitely' long. These cells are set, so if you get fatter or thinner, the 'matrix' never gets bigger or smaller. Additionally, if you damage it, you can damage your nail growth.", "topk_rank": 17 }, { "id": "corpus-80224", "score": 0.7263181805610657, "text": "They grow evenly, but the uneven parts are rounded by wear. Your finger tip is rounded, so any irregular part sticking out would get worn much faster.", "topk_rank": 18 }, { "id": "corpus-12410", "score": 0.7254425287246704, "text": "It does stretch and break, but the nail is moving slowly enough that the tiny injuries and repairs happen without you noticing. The growth occurs under the small patch of skin at the base of the nail. The rest isn't actually alive, it's just hard protein, similar to hair, working its way across the top of your finger. The nail bed (underneath the main visible part of the nail) constantly adjusts as it works its way out.", "topk_rank": 19 } ]

[ { "id": "corpus-325356", "score": 0.6986033916473389, "text": "Oh, an ice cream float!! The dissolved milky fat in the ice cream increases the surface tension in the bubbles, which means they don't pop as easily/quickly." } ]

[ { "id": "corpus-119149", "score": 0.6632423400878906, "text": "Bubbles are already in the liquid. They are made of carbon dioxide, CO2. Drink is pressurized with CO2. Even though CO2 is a gas, it'll dissolve in a liquid - and bigger the pressure, more there is CO2. After the pressure is not holding it in drink, it'll slowly break free, hence the bubbles. Think of it as if the pressure uses rope to tie molecules of CO2 to the liquid. After pressure is no longer there to make sure CO2 is staying where pressure put it, the bubbles will try to escape. Some are better at untying the knots and therefor will escape sooner, some aren't as good and get away later. After all the CO2 has escaped, drink has lost all of it's bubbles and has become still.", "topk_rank": 0 }, { "id": "corpus-8280", "score": 0.6629800796508789, "text": "If it's carbonated, then releasing the pressure causes the gas to expand - which drops the temperature suddenly, which freezes the liquid. It's also possible that the liquid may have been supercooled - that is, it's below its freezing point but unable to freeze because it can't find anywhere to get started. The sudden release of pressure, and the bubbles that form, may be just the starting points (nucleation sites) needed to allow it to freeze.", "topk_rank": 1 }, { "id": "corpus-85580", "score": 0.6628990173339844, "text": "For the same reason that soda pop tastes different after a freeze/thaw cycle...the carbonation is gone.", "topk_rank": 2 }, { "id": "corpus-14350", "score": 0.6623940467834473, "text": "Fat is of different density than water and when left alone has a tendency to float to its top. So if you take whole milk that comes right out of a cow and let it sit for a while, the fat in it, which is the source of almost all of its calories, comes to the top and can be skimmed off. This is why they call milk with the fat removed \"skim milk\" - it's literally been skimmed. You can also leave some in there and then process that milk a little so the fat no longer floats to the top. This results in \"homogenized\" milk that doesn't separate any more into floaty globules of fat on top and water with sugars and proteins in it underneath.", "topk_rank": 3 }, { "id": "corpus-44205", "score": 0.6621211171150208, "text": "Though the contents were not changed how they mix has changed. Something easier to visualize is a milk chocolate bar. If you have put one of those in the freezer and take it out you notice the powder white film along the outside. That is the maltose sugar that separates from the chocolate because it freezes at different temps. The effect on your soda is similar. Of course if you shook the can up since it is a liquid you could probably remix the flavors but that would give you other problems.", "topk_rank": 4 }, { "id": "corpus-180603", "score": 0.6618673801422119, "text": "The co2 that gives the soda its fizz has leeched out of the liquid. Co2 in soda is under pressure so when you freeze it the co2 is pushed out of the water leaving it to taste flat", "topk_rank": 5 }, { "id": "corpus-65006", "score": 0.6616376638412476, "text": "A carbonated beverage is a beverage that has carbon dioxide mixed and pressed into it, which is what gives it that bubbly tingly texture. Cans and bottles are kept at high pressure to contain the gas within the liquid. As soon as that pressure is released by opening the container, the gas starts to come out of the liquid, appearing as bubbles. If you wait long enough, most or all of the gas will leave the liquid - your drink becomes flat.", "topk_rank": 6 }, { "id": "corpus-32136", "score": 0.6608334183692932, "text": "Same reason a mentos makes a coke explode. The bumps in both cases are \"nucleation sites,\" and they help dissolved carbon dioxide form into bubbles more easily. Id link you but I'm on my phone", "topk_rank": 7 }, { "id": "corpus-278552", "score": 0.6607682108879089, "text": "Great question! Have you ever seen what happens when mentos is dropped into a coke? Its the same principle (but usually less messy)! Little air bubbles on the surface (of the ice cream/mentos) act as nucleation sites where CO2 that's dissolved in your root beer rapidly congregate. Water-soluble ingredients in the ice cream change the surface tension of the root beer, trapping formed bubbles in ways it otherwise couldn't.", "topk_rank": 8 }, { "id": "corpus-255795", "score": 0.6591091752052307, "text": "Phase separation of the water and fat in milk. Normally they exist in a colloidal suspension, but heat and degradation of proteins causes them to separate. When ice-cream is made, you have solid ice, but that that solid/creamy fat, suspended within each other. But then (!) when you thaw it, the water separates away and you're left with a similar fat.", "topk_rank": 9 }, { "id": "corpus-150245", "score": 0.6580851674079895, "text": "When **carbonated drinks** are cold the molecules are closer together giving it more reaction and you can taste the effervescence. When it's hot the molecules are spread farther apart so you're not feeling them move, coining the term \"going flat\". **Milk** is the same way but for a different reason. Milk has a slight odor to it, considering that nearly 40% of taste is smell, that odor is more prevalent as the molecules start to spread out due to the increased temperature. When it is cold and the molecules are more closely packed together, the odor is predominately centralized and therefore not as noticeable. **Water** is better because it when it is colder the cold of it eclipses the bad taste of impurities within the water due to the molecules being so closely packed together. When it is warmed up those impurities are moving about much faster and are more spread out and therefore easier to taste. **Source:** Our company used to do taste tests for Schneider-Weiss Brewery.", "topk_rank": 10 }, { "id": "corpus-184162", "score": 0.6580796241760254, "text": "Liquids can hold a certain amount of dissolved gas. When the pressure is raised, the liquid can hold more gas. In a water bottle, the pressure is lower than soda. That's why you don't get the pop when you open it. After you agitate the bottle, the bubbles that formed quickly rise to the top or dissolve back into the water. Soda, on the other hand, has a lot of dissolved sugars and acids. These allow the frothy foam and bubbles to be more stable than just water. The higher pressure also allows more dissolved gasses. After you open it, the gas starts to bubble because the lower pressure of the atmosphere can't push the same amount of gas into the liquid.", "topk_rank": 11 }, { "id": "corpus-180258", "score": 0.6574753522872925, "text": "CO2 interacts with water to form carbonic acid. If you pump a bunch of CO2 through water, a lot of it will react. If you were to leave the resulting solution sitting out, the carbonic acid would eventually start decomposing to form water and CO2 again. That CO2 would form in bubbles and leave the water. So basically, carbonated drinks have lots of CO2 pumped through them and then they're bottled or canned to prevent the CO2 from escaping. If you shake a carbonated drink in a closed bottle it builds up pressure because the shaking causes a bunch of CO2 to leave the water.", "topk_rank": 12 }, { "id": "corpus-245377", "score": 0.6565645337104797, "text": "I have no idea about the white specks. I never noticed that before, but I did place three bottles in the freezer to see if this in fact occurs. Being the scientist that I am I placed a few different water brands / types. One carbonated spring water bottle, one non-carbonated spring water bottle, and one filtered water bottle. The water on the outside is condensation. There is water in the air, but it is present as water vapor (gaseous water). The cold water bottle absorbs some of the heat (energy) for the water vapor in the air causing it to condense on the bottle and reform into a liquid. _URL_0_", "topk_rank": 13 }, { "id": "corpus-105698", "score": 0.6562359929084778, "text": "Yes. When you shake the soda bottle, CO2 that is dissolved in the soda is released into the headspace, the empty space between the cap and soda. The pressure in the headspace will rise. Particularly if the soda is cold, this pressure difference between the headspace and soda will over time cause the CO2 to redissolve until the pressure is equalized. Warmer soda means less CO2 can be dissolved. I can't answer the \"how long does it take,\" part. But if you wait long enough (a couple days?) it will redissolve and the soda won't be flat. If you were to open the soda at any point, that CO2 in the headspace would escape. If you close it back up, there is again a pressure difference, this time the headspace pressure is lower and even more CO2 comes out of solution. Next time you open the soda, it's that much more flat.", "topk_rank": 14 }, { "id": "corpus-115168", "score": 0.6555988192558289, "text": "carbonation is the result of a very unstable acid - carbonic acid (H2CO3). during standard temperature and pressure, carbonic acid splits into water (H2O) and Carbon Dioxide (CO2) - the bubbles in your soda are the Carbon Dioxide. Even though the acid is quite unstable it still takes time for all of it to split, that's why a carbonated soda stays carbonated for some time, but becomes flat after you leave it open for too long. You can aid the acid in splitting, by applying force to it (i.e.: shaking the bottle) and therefore quickening the procedure.", "topk_rank": 15 }, { "id": "corpus-190068", "score": 0.655125617980957, "text": "Beer is made with grain. The grain contains proteins That contribute to the foaming you see. Soda only contains sugar and flavorings that do not foam as much.", "topk_rank": 16 }, { "id": "corpus-43165", "score": 0.6549596786499023, "text": "_URL_0_ During manufacturing, they dissolve carbon dioxide into the candy (it's still a liquid at this point) like soda manufactures do with soft drinks. This process leaves lots of tiny bubbles inside the pop rocks filled with pressurized CO2. When the stuff hardens, the carbon dioxide is trapped inside until your saliva starts to dissolve the rocks.", "topk_rank": 17 }, { "id": "corpus-321579", "score": 0.6544244289398193, "text": "Arguably, a textured glass would make your soda go flat faster. The irregular geometry would promote nucleation sites for the CO2 bubbles. To make your drink stay carbonated longer, the smoother the better. Edit: typos", "topk_rank": 18 }, { "id": "corpus-604461", "score": 0.6543631553649902, "text": "I realize it's typically just ice cream and milk, but when I make them they have a tendency to be somewhat separated, no matter how long I blend it together. There's mostly milkshake type texture, and then there's always a bit of just plain old chilled milk that comes with it too. Any ideas on how to get it completely homogenous, or is that just a normal thing I don't be able to get around? Restaurants and stuff don't seem to have the issue, normally, so I'm wondering if I'm doing something wrong.", "topk_rank": 19 } ]

[ { "id": "corpus-325357", "score": 0.7055737376213074, "text": "Hubble can resolve stars in the Andromeda galaxy." } ]

[ { "id": "corpus-2138621", "score": 0.6702930927276611, "text": "I am currently going through my second year in college and have been looking into getting a new hobby. I've been interested in the night sky my whole life and want to learn what I can. I just don't know where to even begin. I've watched quite a few documentaries but now I would like to take it into my backyard and do some actually viewing. \n\n\n\nThis is the telescope that I am strongly considering to buy, what would I be able to see with it? Is this a decent telescope to start with? \n\nWith your experience how do I even break into such a vast and rich field?", "topk_rank": 0 }, { "id": "corpus-299864", "score": 0.6702743172645569, "text": "I guess it depends on what you mean by \"useful\". We have a satellite in Earth orbit (not Sun orbit) called [RadioAstron](_URL_0_) that is part of the very long baseline interferometry effort with other satellites on the ground here. Since the baseline is enormous, it gives you much better angular resolution. In principle you could have many more of these, we just don't at the moment.", "topk_rank": 1 }, { "id": "corpus-262729", "score": 0.6702554225921631, "text": "Yes. There certainly exists a market for x-ray optical equipment, either to focus x-rays like you would need to do on the Chandra telescope (basically the Hubble telescope of the X-ray spectrum), or in x-ray spectrometers and microscopes. I would not be surprised if X-ray rated optical pieces would be what some specialist somewhere calls \"lab equipment.\"", "topk_rank": 2 }, { "id": "corpus-168137", "score": 0.6702218651771545, "text": "If I asked you to snap a picture of Mt. Fuji, you probably could right? Know if I asked you to take a picture of a fly/mosquito 50ft away, it would be difficult right? Galaxies are much, much larger, and also much more bright.", "topk_rank": 3 }, { "id": "corpus-316977", "score": 0.6702048778533936, "text": "Yep, perfectly possible, for the larger/closer satellites at least. For example, [here's an old image I took of the ISS](_URL_0_) by simply hand tracking an amateur sized Dobsonian with an old video camera strapped to the eyepiece. The Shuttle's were good targets too, while they were still in use. As /u/CoBr2 points out, things get more difficult with smaller/further away satellites. People are still able to do it, but the resultant images aren't \"high resolution\". Some examples: _URL_1_ _URL_3_ _URL_2_", "topk_rank": 4 }, { "id": "corpus-321013", "score": 0.6700918078422546, "text": "I think the question is more like if we were a planet orbiting a star which has been ejected from a galaxy and is say a 100,000 ly above that galaxy, would someone on the planet see something like [this](_URL_1_) in the night sky? *edit: [Carl Sagan quote](_URL_0_): > ...But from a planet orbiting a star in a distant globular cluster, a still more glorious dawn awaits, not a sun-rise, but a galaxy rise.", "topk_rank": 5 }, { "id": "corpus-2720080", "score": 0.6700657606124878, "text": "This star is inside the Formidine Rift, extremely bright, so much so that it can be seen from 1000s ly away, from pretty much anywhere in the Rift. However, it seems virtually impossible to get to (at least for my puny Asp). If you attempt this challenge, try to take enough jumponium for the way back too ;).", "topk_rank": 6 }, { "id": "corpus-298550", "score": 0.6699779629707336, "text": "You are correct in saying that we cannot 'see' through the center of the milky way. As you hinted at, there is a large amount of dust in the galactic plane which blocks light that we would describe as being in the visible portion of the electromagnetic spectrum. However, it is possible to peer through this dust using different wavelengths of the spectrum. One such wavelength is simply radio waves. Using radio telescopes, astronomers are able to get past the dust and observe objects in the center of the galaxy and beyond. Now, observing things on the far end of the galaxy can certainly be difficult, as there are a great number of radiation sources in the way. However, making use of radio waves and other wavelengths, such as x-rays, would surely allow us to observe something as high in radiation as an entire galaxy.", "topk_rank": 7 }, { "id": "corpus-324671", "score": 0.669902503490448, "text": "You've hit upon a very old question called [\"Olbers' Paradox\"](_URL_0_). The solution relies on the fact that the universe is not infinitely old, so only finitely many stars and galaxies are observable and they collectively subtend an angle on the sky much smaller than the full sky.", "topk_rank": 8 }, { "id": "corpus-325319", "score": 0.6698873043060303, "text": "There's this concept called [Schwarzchild radius](_URL_1_). If you cram too much matter into too small a space (smaller than the Schwarzchild radius for that mass) then the gravity would be too strong for even light to escape. We call the resulting object a black hole. Cramming the entire universe into a box would result in a mondo black hole. There is also a lower limit to the mass a star can have and still shine; anything below 75 times the mass of Jupiter has insufficient pressure to fuse hydrogen. I am sorry, but there is no way to realize your dream of having a pet universe in your living room. The best you could get would be a [rough computer simulation](_URL_0_) - which is still fairly impressive.", "topk_rank": 9 }, { "id": "corpus-303935", "score": 0.6698567867279053, "text": "Take a good telescope, and catalog the stars you can see. [Compute their distance](_URL_0_). Then plot everything in 3D, and you'll see that the stars that are reasonably close to us, form a spiral, and that we are roughly in the middle of one of the \"arms\" of that spiral.", "topk_rank": 10 }, { "id": "corpus-321714", "score": 0.6698513031005859, "text": "Yes. [This](_URL_0_) is a release from 1997 detailing a collection of stars that were found to be in intergalactic space. Such stars can be ejected from their galaxies for various reasons, often involving close approaches with other massive bodies that produce slingshot effects that catapult the stars out of the galaxy, often at relatively high speed.", "topk_rank": 11 }, { "id": "corpus-1271852", "score": 0.6697115302085876, "text": "Hey guys,\nso I'm sitting in my backyard right now and I'm watching some Planets (Jupiter, Saturn, Mars) no problem with these. Easy to find and I can spot some details. Awesome.\nBut as soon as I try to find some Deep Sky Objects (which I finally did), they look just like a white-ish spot no matter how much I magnificate. 🤔😕 (I found (or I think I found) M13 and Andromeda Galaxy) I live in a small village near Hanover (35km away). Slight light pollution. RN sky is very clear. \n\nSpecs: Orion SkyQuest XT 4.5 (4.5 inch aperture) 900mm focal length, Dobsonian mount.\nSirius Plössl 25mm, 10mm and an Omegon 6mm UWA.\n\nThanks in advance and clear skies!", "topk_rank": 12 }, { "id": "corpus-317979", "score": 0.6697053909301758, "text": "Not only possible but has been [suggested](_URL_0_) that robotic landers deploy such a thing. It is likely that it will not only be desirable to have radio telescopes on the Moon at some point but it may actually become necessary. The far side of the Moon is likely to soon become the only place we can be free of radio frequency interference that already prevents us from observing a great number of galaxies and other sources. This is likely to get far worse as we become more and more a wireless society.", "topk_rank": 13 }, { "id": "corpus-301473", "score": 0.6696830987930298, "text": "At night, in areas without light pollution from cities, you can see part of the rest of our own galaxy. We're about midway out on just one of the arms. If I recall correctly, the only part we can't see at all is a wedge blocked by the cloudy galactic core. Pics of the whole galaxy are computer generated but we can use what we can see from here to extrapolate the \"view from above.\" Map: _URL_0_ View at night: _URL_1_", "topk_rank": 14 }, { "id": "corpus-1190772", "score": 0.6695893406867981, "text": "After just buying some decent bins my interest in Astronomy has been tweaked again. Now I’m starting to look for a scope. \nAs stated in title I’m looking for impeccable optical quality and for detailed planetary viewing how far do I have go lens wise?\n\nI want to put the major expenditure into the optics yet still have a good solid easily controlled reliable mount to be used from a sitting position. \n\nLocation is north central Toronto Canada. \nAs far as budget goes the old “whatever it takes” applies here but I think about 5k would be max. \n\nI’m going to spend a little time checking this all out but suggestions for the best viable choices and anything I might have missed would be greatly appreciated. \n\nThanks.", "topk_rank": 15 }, { "id": "corpus-310900", "score": 0.6695305705070496, "text": "Very high, actually. Galaxies might look kinda dense, but the stars are actually very far apart relative to their size, so the likelihood of two stars even coming close to each other during a galactic \"collision\" is very small. It will be chaotic on a galactic scale, yes, but at the scale of a single solar system it's very unlikely that you'll see any change other than the night sky looking different.", "topk_rank": 16 }, { "id": "corpus-250232", "score": 0.6694657802581787, "text": "Yes, there is an angular resolution limit, which is the smallest angle you can differentiate, which is what you are asking. That's about 1 arcsecond, or 1/60th of a degree. There's also a minimum distance at which the eye can focus, about five to ten inches or so (increases with age) which is why if you hold your finger an inch in front of your eye, it's blurry, and you can't see those bacteria no matter how close you get. Saturn is large enough that it is somewhat more than 1 arcsecond across at this distance, so it is visible.", "topk_rank": 17 }, { "id": "corpus-182776", "score": 0.6694632768630981, "text": "Depends on your definition of \"relatively large\", but yes, and are sometimes referred to as Trojan asteroids. These can (and do) exist for almost all the planets (even earth has *some catalogued), but the majority of known, large ones share Jupiter's orbit easy rule of thumb for stability (although it's a bit of a fudge) is: m1 > 100m2 > 10000m3 i.e. if the star is greater than 100 x the mass of the planet, and 10000 x the mass of the Trojan, the system will be stable for quite some time (again, definitions vary on \"quite some time\") *edit: more than one", "topk_rank": 18 }, { "id": "corpus-1192121", "score": 0.6693618297576904, "text": "Be carefull of 114, 127, 130 and 150mm short fat reflectors with Focal Lengths of 875mm or more. Amongst their shortcomings, Bird-Jones Telescopes are notoriously difficult to collimate.\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nPlease list any others you might have spotted. I bought a Celestron 127EQ, which I now regret, and wish I had done better research! This particular instrument rated high on Amazon, so be aware that good ratings should still be carefully investigated!\n\nFor new Telescope Buyers, be carefull of these! For the same price you can get better products (typically, reflectors with lower focal lengths). Anything from about 400 -750mm should be a better choice.", "topk_rank": 19 } ]

[ { "id": "corpus-325358", "score": 0.7113149762153625, "text": "Feasible - yes. In practice its never done because the removal will lead to some ischemic damage, living donors are specifically selected for their ability to live a healthy life with only one kidney, and the risk of adverse events during implantation is significant." } ]

[ { "id": "corpus-95766", "score": 0.6752275228500366, "text": "I haven’t seen anyone mention the fact that once inside the recipient the donated organ will be under constant attack from the recipients immune system, which will prematurely age the organ. Because of this transplant recipients take immunosuppressive drugs to reduce the amount of damage their own immune system will do to the new organ. It’s a balancing act between suppressing the immune system enough to stave off rejection of the new organ (which is almost always inevitable) and having enough of an immune system to fight off basic infections. This is why it can be difficult to find a match when looking for an organ. The closer the new organ is to the recipients own genetic markers the better. Source : I used to be an RN on an transplant unit.", "topk_rank": 0 }, { "id": "corpus-246390", "score": 0.6751453876495361, "text": "Not sure about donor adrenals but I do know that unless there is an overwhelming reason, the recipient's kidneys are left in place. The donor kidney is taken along with enough vasculature to connect into the recipient's vasculature. So a patient who has undergone transplant will have three kidneys afterward. The adrenals have never been removed and should still have blood supply so perhaps they still function. If the transplant kidney fails and they get another then one could end up with four kidneys, as long as there's no indication for taking out the first transplant.", "topk_rank": 1 }, { "id": "corpus-2596597", "score": 0.6747049689292908, "text": "I've been thinking about living organ donors. The reason is obvious when it is to save the life of a loved one, but there are many people who donate to someone they don't (and may never) know.\n\nMy question is: why would it be better to donate, for example, one kidney when you are alive, rather than just Register as an organ donor and when you die your organs are used. You save a life now or a life later. With all things being equal, what is the benefit of donating before you die? \n\nI have looked for an answer but can't seem to find one and I feel I am missing something here.", "topk_rank": 2 }, { "id": "corpus-316152", "score": 0.6745994091033936, "text": "[Here](_URL_0_) is a thread asking the same question. The Top answer says, \"The transplanted organs will grow appropriately with the child as they age as they would have in the donor's body as is governed by the normal cell's cycle and physiologic changes.\"", "topk_rank": 3 }, { "id": "corpus-285691", "score": 0.6731793284416199, "text": "Short answer is that it *does* identify them as foreign objects. Organ transplant recipients are given a variety of drugs that they have to take for the rest of their lives that force their bodies to accept the organs. I think.", "topk_rank": 4 }, { "id": "corpus-305836", "score": 0.6731067895889282, "text": "You can't look at it like a car, where you can just replace the bad parts with new parts and keep it going. Organ replacement in it's current state isn't that simple. Once a person receives a transplant, they need to be placed on immunosuppressant drugs to prevent organ rejection. They sometimes need to remain on them for the life of the organ. These drugs have lots of side effects, including (as you might guess when you impair someone's immune function) increased infection risk among many other serious complications. Infections are a leading cause of death among transplant patients. Now if medicine reaches a point where we're growing organs from your own stem cells, there could be a different story.", "topk_rank": 5 }, { "id": "corpus-319985", "score": 0.6729393005371094, "text": "Depends on the organ. Livers can regenerate from a small nubin, so we would implant a small baby sized liver and it would grow. I think kidneys are implanted whole, hopefully in bigger children. These also can hypertrophy (get bigger) as needed. Hearts would be very unusual. Not sure it could work without a similar sized donor. As far as I know (not a paediatric transplant surgeon!) the goal is to delay transplant as long as possible so sizes work better. So in the heart they do a while bunch of weird operations like cutting out bad pieces and sticking vessels in weird spots, as a temporary measure. Past that, I think the odds of getting a super-specialist in here are low, but there will be tons of case reports in the literature. Just google \"paediatric transplant\" with the organ of interest", "topk_rank": 6 }, { "id": "corpus-309674", "score": 0.6717249751091003, "text": "The body generally does not \"get used\" to a transplanted organ. There are a few mitigation measures, though, to address the most severe of \"quality of life\" issues. For one, donor and recipients would be matched for histocompatibility. This is the reason why closely related family members often make the best donors. In some types of transplants, such as bone marrow for example, the donor's immune system itself is effectively transplanted over. One thing to keep in mind is that those who have access to organ transplants are generally in developed parts of the world, where access to immunosuppressants usually isn't a problem. This raises inequality issues, which is a different ball of wax entirely.", "topk_rank": 7 }, { "id": "corpus-146742", "score": 0.6701721549034119, "text": "Doctors will be able to decide which or your organs are suitable for donation. If you are fairly healthy and die in an accident that did not cause trauma to your heart, liver, etc, these will be donated. It depends on what you died of and your overall health. The hospital will alert the person in their district who is responsible for collecting organs and finding matches for them. The body will go to surgery, where doctors will remove the selected organs and they will be prepared for transport and kept cool.", "topk_rank": 8 }, { "id": "corpus-272033", "score": 0.669850766658783, "text": "This has happened in the past with [livers](_URL_1_), [auxiliary livers](_URL_0_), [kidneys](_URL_2_), and possibly other organs as well. There's a growing pressure to increase organ retransplantation, since there is such a limited supply. With regards to the number of times an organ can be passed on, remember that transplanted organs are still subject to the effects of aging. Many of the effects (eg telomere shortening) would still occur. Currently, it looks like the maximum number of cycles is at 2, but that may not be due to any hard biological rules.", "topk_rank": 9 }, { "id": "corpus-78639", "score": 0.669719398021698, "text": "Assuming you are in good health when you donate the kidney and don't have any outstanding illnesses and there aren't any complications with the surgery, studies have showed that their quality of life and overall health do not diminish over someone who has not donated a kidney.", "topk_rank": 10 }, { "id": "corpus-973639", "score": 0.6691955327987671, "text": "I was going to post a shower thought about this but after reading I noticed this only applies to deceased organs.\n\n\n\nAlso it appears to apply primarily to people doing the transaction. Can you get around this by using an LLC to handle the transaction?\n\nFinally, Why wouldn't life insurance companies support compensating donors if it meant keeping their clients alive longer? \n\nI understand not all operations would be profitable (ie: $50k for an organ that only has a small percentage of saving their life would be adverse) but from what I've read things like kidneys and livers are almost a 90% survival rate 5+ years", "topk_rank": 11 }, { "id": "corpus-147580", "score": 0.667838454246521, "text": "Just wanted to note that the kidney is not in the peritoneal cavity with the rest of your organs, the space where it was will flatten, enlarging the peritoneal cavity a little and thus replacing the lost space with your other organs. In the case of day your liver, you would only donate part of it, and it would grow back to almost full size over a month or so.", "topk_rank": 12 }, { "id": "corpus-301561", "score": 0.6673685312271118, "text": "No, the DNA stays the same as it always was. That's why it's so important to find as close a genetic match as possible to limit the need for anti-rejection drugs. If the immune system of the new host finds the new DNA it will try to destroy the organ.", "topk_rank": 13 }, { "id": "corpus-1758512", "score": 0.6665874123573303, "text": "I am a kidney transplant patient that got a kidney 6 months ago. I am going to visit a friend today. It has been a long time since I have gone to his house. He has 2 cats and 1 dog. I am not sure if I should be worried since transplant team told me not to be around pets.", "topk_rank": 14 }, { "id": "corpus-2596571", "score": 0.6658491492271423, "text": "My question comes after this comment. \n\nA few years ago my friend told me the rules are different for resuscitating organ donors.", "topk_rank": 15 }, { "id": "corpus-2599489", "score": 0.6657951474189758, "text": "If i donated my heart for example to another person after i died, this person has no problems with the heart, leads a healthy lifestyle and then donates the heart again after they die, how long could this go on for, do our organs have a certain lifespan or could they go on and on working in different bodies?", "topk_rank": 16 }, { "id": "corpus-324881", "score": 0.6656988859176636, "text": "Depending on the organ, it would most likely be the donor DNA. But, host cells can infiltrate and become part of the organ. Some tissues would convert over completely like a skin graft. Others would be partial like a heart. Liver and Kidney would probably stay mostly just donor.", "topk_rank": 17 }, { "id": "corpus-65807", "score": 0.6650339365005493, "text": "Because taking tissue from one person and implanting into another is more complicated than you might think. There are all sorts of antibodies that have to match, and even then the match is never perfect, so organ recipients are typically on immunosuppressant drugs for the rest of their life. Plus, there is probably more breast tissue getting augmented than removed.", "topk_rank": 18 }, { "id": "corpus-175806", "score": 0.6647776365280151, "text": "When you get a kidney transplant they leave the old kidneys in the body unless they are causing problems. If it is rejected and causing complications it gets removed and the person has to get back on the transplant list and gets back on dialysis.", "topk_rank": 19 } ]

[ { "id": "corpus-325359", "score": 0.712559700012207, "text": "No, it's the opposite. As temperature increases, the molecules in a liquid push against each other more and more, slightly increasing the volume. It's not huge, but you get the best value in gasoline if you buy early in the morning. > Why does water expand anyways in colder temperatures? When water freezes, it expands. This is because water is shaped like /'\\ . What it's a liquid, all those V shapes jumble about randomly. When it freezes, they form neat /'\\ \\,/ shapes, with each end of the v hooking into each other. These crystalline structures take up a bit more space than V's jammed into each other, so volume increases. However, if water freezes at much lower temperatures or higher pressures, it can form less compact forms of ice that don't take up as much space." } ]

[ { "id": "corpus-17948", "score": 0.6766122579574585, "text": "It's about the octane number of gasoline. In a gasoline engine, the air-fuel mixture is compressed by the cylinder, then ignited by the spark plug. If the octane number of the gasoline is too low, the mixture might already ignite from the compression alone. This throws the engine's timing off, and it might even damage the engine. Lead (or rather tetraethyllead) was an easy, relatively cheap additive that would raise the octane number, making the fuel a bit more stable under compression. It has been phased out since the 70s, when it was discovered that the lead was very bad for the environment.", "topk_rank": 0 }, { "id": "corpus-18500", "score": 0.6763458251953125, "text": "Your battery uses a chemical reaction to produce the electricity needed to run your car. When it's cold out this reaction slows down, decreasing power output. Your engine oil also gets thick when cold. It's harder to move engine parts through thick oil.", "topk_rank": 1 }, { "id": "corpus-530198", "score": 0.6758185625076294, "text": "I go to the gas station and there are four types of gasoline (normal, premium, supreme and ultra), each with different additives like cleaning stuff, antifreeze, antigunk, gods know what else. Do they actually do anything or are they just a way to 'water' down the gas?", "topk_rank": 2 }, { "id": "corpus-323037", "score": 0.6755589842796326, "text": "The gas only cools down when it expands. It remains at room temperature when in the liquid state.", "topk_rank": 3 }, { "id": "corpus-181150", "score": 0.6753314733505249, "text": "If you turn on the engine, and immediately begin to do something that requires significant energy, the engine will begin working faster. This in turn, as we use combustion engines, generates heat, assuming your car has been out in the cold, your rather massive engine block stores said cold very well. So, by rapidly pushing out extreme heat into metal that is already very cold, the outermost parts of the metal expand while the inner parts stay cool. This causes strain that will overall shorten the life of the engine, but not cause significant harm on its own. The effect can be seen on a more visible scale when you pour hot water onto cold glass", "topk_rank": 4 }, { "id": "corpus-303920", "score": 0.6750377416610718, "text": "Virtually every chemical reaction has an activation energy associated with it. Especially for combustion reactions, you are breaking and forming numerous bonds on your way from reactants to products. In order for a new bond to form, the old one often has to be broken. This requires that energy be added to the system. Even at room temperature, there is a chance that an individual molecule of gasoline has enough internal energy to react with oxygen, but it is an exceedingly small chance. Even for reactions that only form bonds, there is a (smaller) activation barrier to them occurring because the molecules still have to deform somewhat in order to accommodate the new bond.", "topk_rank": 5 }, { "id": "corpus-157873", "score": 0.6747184991836548, "text": "It's called a \"winter front\" and helps keep the engine warm by restricting airflow across the radiator. Diesel fuel turns to jelly when it gets too cold, and in subzero temperatures the radiator actually works too well, cooling the engine below optimal operating temperature and can let the fuel gel up in the fuel lines. Gelled fuel won't fit through the injectors, starving the engine. Source: 10 years OTR", "topk_rank": 6 }, { "id": "corpus-308040", "score": 0.6747136116027832, "text": "Yes, it is. To get any reaction there must be energy put in. The colder a fuel is, the more energy that has to be put in to get it to burn. To put it another way, a fuel has an ignition temperature. The fuel will not burn until it reaches that temperature, and if it is cold it will require more heat to get to that ignition temperature. Rubbing alcohol, for example. At room temperature it burns vigorously and self-sustained; frozen with liquid nitrogen it will burn when a torch is applied, but it will not sustain a flame. (This is partly because for it to burn it has to first vaporize, and to vaporize it must be liquid, so it vaporizes more slowly because it has to pull the heat of fusion out of the fire before it can vaporize.)", "topk_rank": 7 }, { "id": "corpus-92920", "score": 0.6745126247406006, "text": "Metal (and many other materials) expands when it warms up and contracts when it cools. The components rub together a little bit as they change size. The noisiest bits are usually the exhaust system.", "topk_rank": 8 }, { "id": "corpus-159630", "score": 0.6744338870048523, "text": "The engine has to run richer in order to function when cool, and this uses more fuel. The thicker oil in the engine and transmission takes more power to push around. It also takes extra fuel to push water (or sow) away as you drive. Balancing all this, cold fuel is more dense, and contains more energy per litre.", "topk_rank": 9 }, { "id": "corpus-30750", "score": 0.6744222044944763, "text": "The higher you go, the lower the air pressure - there's less air atop it. When the pressure goes down, gasses (air included) expand. When gasses expand, their temperature goes down; the same heat energy is spread over a wider area, less contained, and the molecules are better able to pick up more energy then they would when they're packed together. [And here's an experiment you can do](_URL_0_) to demonstrate it, including a more detailed explanation. :D Mind you, if there's snow on the ground it also reflects sunlight and makes it harder for the local area to heat, and there are other factors as well, but I believe expanding gasses moving higher is the key.", "topk_rank": 10 }, { "id": "corpus-322098", "score": 0.6740127205848694, "text": "[Adiabatic expansion](_URL_0_) Temperature rises with pressure because the molecules are being pushed together to fit into a smaller volume. Similarly when a piston rises in a diesel engine it compresses the mixture of fuel and air until the increased temperature causes it to explode. Also: Take care with containers of fuel. You could blow yourself up that way.", "topk_rank": 11 }, { "id": "corpus-289046", "score": 0.6739346981048584, "text": "Slightly. I don't have the numbers but I know that petrol retailers complain to the distributors if the fuel which is supplied to them is too warm. Higher temperatures mean less mass per unit volume, and the retailers pay by volume for the fuel. They sell by volume too, but they can't keep the fuel warm so they lose volume as it cools.", "topk_rank": 12 }, { "id": "corpus-28232", "score": 0.6738349795341492, "text": "Conceivably, yes, but keep in mind that gasoline and diesel also produce a large amount of water when they are burned--ever seen the exhaust of a car on a cold morning? That's the moisture in the exhaust showing up as fog briefly before it dissipates, much like when you see your breath in the same conditions.", "topk_rank": 13 }, { "id": "corpus-14819", "score": 0.6735643744468689, "text": "When gas expands, it cools down. It's sort of because the molecules are a lot less crowded together (you can imagine how hot and stuffy you feel in a crowded subway car, and then you feel a lot cooler once you have some space). This is actually the premise behind how your refrigerator and air conditioner work. Your air can is actually acting like a personal AC unit!", "topk_rank": 14 }, { "id": "corpus-53652", "score": 0.6733695268630981, "text": "Diesel engines are very temperature sensitive; diesel fuel gets too thick to run an engine if it gets too cold. As an engine runs, it gets warm, which helps the diesel fuel. However, if it's warm outside, you don't want the engine to overheat, so you want a lot of air blowing over the engine and radiator to balance it out. If it's cold outside, and you're driving down the road, that's a lot of cold air blowing on the engine, so it's harder for the engine to stay warm, so covering up the front allows the engine to run hotter, which is better , but the ambient air is too cold for the engine to really overheat. Here in North Dakota with super cold winters, we even cover up the fronts on gasoline engines, because the interior heat comes off the engine and it can be hard to warm up the inside of the car if you're driving fast in below-zero weather.", "topk_rank": 15 }, { "id": "corpus-57900", "score": 0.6733223795890808, "text": "This can happen. Some cars have completely bizarre fuel tanks with [two connected tanks with a secondary pump](_URL_1_), but the more likely issue is contamination of the gasoline. Gasoline is lighter than water, so if water gets into the gasoline it will sit at the bottom of the of the tank more or less forever. Ethanol in gasoline can make this problem a bit worse because ethanol absorbs water from the air better than gasoline does, and then the ethanol and water mixture will separate from the gasoline and sit at the bottom of the tank. Because water, or solids (like rust), will sit at the bottom of any gas tank, the fuel line is usually designed to that it will draw fuel from the top of the tank if possible, and only switch to a tube that sits near the bottom of the tank when the fuel level gets low. If it is a bit of water you can sometimes just use a [gas dryer](_URL_0_). If the problem is other crud at the bottom of the tank, it may require pumping the tank out.", "topk_rank": 16 }, { "id": "corpus-276979", "score": 0.6732719540596008, "text": "Well, this isn't a \"chemical explosion,\" but the rapid expansion of pressured gas—say a ruptured tank—can become *incredibly* cold very quickly during the expansion which can be as violent as any normal explosion.", "topk_rank": 17 }, { "id": "corpus-3290", "score": 0.6723847389221191, "text": "No. The sealed bottle or can is much closer to an enclosed system than an open container - it can stay very well carbonated for months. It would be a reasonable simplification to say that the carbonation hasn't changed at all. However, there is another property that is important, Solubility. When you open up the can, the drink itself will lose carbonation due to relatively low levels of CO2 compared to the container it was stored in as time goes on. When the drink is colder, CO2 (and other gases) are more soluble. So, as the temperature increases, there is less dissolved CO2, which likely causes the impression that the drink was less carbonated to begin with.", "topk_rank": 18 }, { "id": "corpus-68357", "score": 0.6723646521568298, "text": "Butane gets thicker when cold so it doesn't come out as fast so it only produced a small Flame.", "topk_rank": 19 } ]

[ { "id": "corpus-325360", "score": 0.70455002784729, "text": "What you're describing is called a free expansion of the gas, which is an irreversible process. You're correct in saying the internal energy stays constant, but U is only a function of T only for ideal gases. So for ideal gases free expansion is isothermal, but real gases do change in temperature. In free expansion you have an entropy increase even though there's no heat exchange, because the process is irreversible." } ]

[ { "id": "corpus-162423", "score": 0.6693094372749329, "text": "Negative air pressure. Warmer air takes up more volume than cooler air. When food is hot, and you seal it in an airtight container, the remaining air in the airtight container is warmed by the hot food. As the food cools -- even a little -- the air temperature also cools. As the air temperature decreases, the cool air takes up less volume than the warm air. Normally, that doesn't cause any other changes because other air will rush in to fill the reduced space. However, because the container is airtight and no additional air can get in to take up the now-available volume, the pressure in the container decreases relative to the air outside the container. That greater air pressure on the outside compared to the inside causes the sides / top of the container to collapse inward. It's basically a smaller scale version of [this](_URL_0_).", "topk_rank": 0 }, { "id": "corpus-1123526", "score": 0.6692612171173096, "text": "I know that hot air will tend to rise, presumably because of density differences. \n\nI also know that we can't effectively separate different gases of different molar mass by allowing the gas to settle into layers, like in a multiphasic liquid extraction, but I have heard that centrifugation is possible.\n\nI also know that helium tends to drift into the upper atmosphere when released and that I can pour SF6 into a cup.\n\nAre all these statements true? I suspect the answer is, \"Brownian motion dominates buoyancy\", but I'd like to hear from an expert.\n\nThanks!", "topk_rank": 1 }, { "id": "corpus-798116", "score": 0.6690599322319031, "text": "In the 2nd step of carnot's cycle, when the gas cylinder is kept under an adiabatic condition, it expands and the temperature falls. My question is why does the gas spend it's internal energy to expand?Since it's internal energy is not changed from the beginning as the entire heat gained in the 1st step of isothermal expansion is spent as work done.", "topk_rank": 2 }, { "id": "corpus-92319", "score": 0.6689363718032837, "text": "A very cool little piece of physics called [the venturi effect](_URL_0_), which basically senses a change in air pressure when the fuel backs up into the fill line and fires a valve that cuts off the gas.", "topk_rank": 3 }, { "id": "corpus-313097", "score": 0.6688709259033203, "text": "No, hot gas or liquid rises due to the fact that almost all materials decrease in density when heated and thus become more buoyant. As there is no gravity on the ISS (or, more correctly, because it is in free-fall) hot fluids will not rise. This has the effect of making [fire](_URL_0_) behave quite differently.", "topk_rank": 4 }, { "id": "corpus-44535", "score": 0.6687814593315125, "text": "Nope - anything you add to the sun will turn into a hot gas well before it reaches the mass. Once it hits the actual sun, it will add to the mass, and make its fusion happen at a faster rate - which makes the sun even hotter than before.", "topk_rank": 5 }, { "id": "corpus-155874", "score": 0.6684780120849609, "text": "You live in the troposphere. This is the lowest layer of the atmosphere. It is primarily heated by the sun striking the surface of the Earth. Some of that energy is absorbed, and re-released as heat, heating the air above the ground. So that's why it is hottest at the surface, it's closest to the 'heater,' the ground. As for why it's cooler as you go up, as hot air rises, it gets less dense (there's less air pushing down on it). This allows it to spread out, effectively expending some of its energy as work, 'pushing' against the rest of the atmosphere. In actuality, there are other layers of the atmosphere above the troposphere where temperatures are *much* higher... *but* because the gasses are so thin at that juncture, temperature isn't as meaningful a measurement of how you'd feel. You'd rarely interact with the atmosphere, and so not get cooked.", "topk_rank": 6 }, { "id": "corpus-312031", "score": 0.6684278249740601, "text": "It sounds like you are describing [vacuum distillation](_URL_0_).", "topk_rank": 7 }, { "id": "corpus-160012", "score": 0.6684210896492004, "text": "Short Answer: it isn't cooler. Longer Answer: This is related to how we can cool down hot food by blowing on it. In short, hot objects will lose heat to the air they're in contact with. The hot air will then float away and cool air will come in and make contact with the hot object. If there is no wind, this process can be slow. But if we blow air over the object, a larger amount of cool air will make contact with the object and take more heat with it. Same thing when we blow air out of our mouths. When we blow air with pursed lips, the air is travelling faster than with our mouths wide open. This is because the same amount of air has to travel through a smaller opening, so it has to travel faster to make up for it. If we blow on the back of our hand with pursed lips, the air will be blowing faster, which allows more air to take more heat from your hand. This is similar to how a fan works. Higher settings feel cooler because more air is blowing on you which takes away more heat.", "topk_rank": 8 }, { "id": "corpus-320815", "score": 0.6683623194694519, "text": "Yes it can, it's just much harder to compress than a gas. At the bottom of the ocean it's compressed by a few percent. If you compress it by about 10 percent without changing the temperature, you get an exotic phase of ice.", "topk_rank": 9 }, { "id": "corpus-181630", "score": 0.6681588292121887, "text": "Air (or at least some gasses in air, like oxygen and nitrogen) can get dissolved into water, and eventually it'll be released by the water. Water can carry more gasses when it's cold (or under pressure), so as it warms to room temperature they're released. Think of it like the opposite of dissolving sugar or salt in hot water and letting it cool, at which point it'll leave deposits on the surfaces of whatever it's in.", "topk_rank": 10 }, { "id": "corpus-192927", "score": 0.668122410774231, "text": "Imagine your body has the same properties as air and I placed you into a box that you fit into perfectly. I cool you down, you condense (take up less space) and as such, your body stops touching the wall of the box and you have more room to wiggle. Now say I heat you up and you expand, you're going to start pressing up against the sides of the box as you take up more space. That pressing up against the wall as the temperature increases is where the increase in pressure comes from.", "topk_rank": 11 }, { "id": "corpus-2642813", "score": 0.6680179834365845, "text": "I heard that if you hold in your fart the pressure will build up until the gas diffuses into your blood vessels and gets exhaled. Is this true or as crazy as it sounds?", "topk_rank": 12 }, { "id": "corpus-374029", "score": 0.6679676175117493, "text": "I am a finance guy, my physics knowledge is limited to highschool physics classes. Here is the story, my house has a bonus room above our garage. This room is not linked to the central duct system in the rest of the house. It has baseboard heating for the winter and in the summer obviously gets quite warm without A/C. My girlfriend comes home from the store yesterday with a portable air conditioner to remedy the problem. I have seen these types of units before, but the ones I've seen have a hose you lead out the window that vents the hot air outside, this unit has no such hose. When on, it blows substantially cooler air than the ambient air out of the front of the unit. When I put my hand near the back of it I feel heat radiating from the unit. \n\nMy thoughts are although the unit blows cool air, without a way to vent warm air outdoors the net temperature of the room should not change. If anything it should slightly raise the temperature of the air with the heat given off my motors and pumps (most likely a negligible amount)?\n\nAlthough the cool air blowing directly on you provides some relief, would conservation of energy state that this unit is essentially useless?", "topk_rank": 13 }, { "id": "corpus-65551", "score": 0.6679399609565735, "text": "Pretty much immediately, because of the pressure inside the balloon. The only reason balloons stay one size is because the pressure inside the balloon equals the pressure outside. When the internal pressure is larger, the balloon expands until it's equal again (increasing volume decreases pressure) and the opposite is true. So in a vacuum, the internal pressure would be much greater than the external pressure so the balloon would expand and expand until it could stretch no more, then pop.", "topk_rank": 14 }, { "id": "corpus-23827", "score": 0.6678972840309143, "text": "Gas is a state of matter that fills the volume of the container in which it is released. Imagine you had a room that was a perfect vacuum, and you opened a small bottle of compressed oxygen in there. The oxygen would expand to fill the room, at a commensurately lower concentration. The same would happen in space Your huge bag of oxygen would open up, and the oxygen in it would dissipate throughout the universe. This, of course, would take a very long time.", "topk_rank": 15 }, { "id": "corpus-324382", "score": 0.6677923202514648, "text": "Nope. Even the world's best vacuum systems will, in general, leak a bit of helium. Its simply too small, light and non-reactive to be contained by most materials. I have spent many hours trying to bring down my helium peak in high vacuum experiments.", "topk_rank": 16 }, { "id": "corpus-272455", "score": 0.6677629947662354, "text": "Heh, finally my job is useful. I design vacuum chambers for a living. The short answer is no, we cannot achieve a perfect vacuum. Even the best pumps, like cryopumps, which actually condense gas molecules onto the pump surface, cannot get every single molecule. Even if you could capture all molecules all materials outgas slightly, meaning they emit gas particles. So you will constantly have molecules entering the chamber. We use special cleaning methods, low outgas materials, and even bake hardware to try and reduce this but it still happens. We cannot even create a vacuum equal to that in outer space. Hope this helps.", "topk_rank": 17 }, { "id": "corpus-168116", "score": 0.667690098285675, "text": "In a theoretical, perfect vacuum, no. With no particles, there is nothing with energy to make temperature meaningful. But most vacuums aren't perfect and thus have some particles floating around with some amount of energy and thus some temperature.", "topk_rank": 18 }, { "id": "corpus-67481", "score": 0.6676154136657715, "text": "At a guess, because liquids and metals transfer heat much more efficiently than gases. Metals and liquids at room temperature are cooler than your body, and transfer heat from your body upon contact, thus feeling much cooler. I'm not a physicist though, so i could be completely wrong.", "topk_rank": 19 } ]

[ { "id": "corpus-325361", "score": 0.7861554026603699, "text": "As /u/W00ster said, this is hard to observe. We rely a lot more on computer simulations or theoretical predictions. From this we infer that in those dense regions the orbits of planets are not stable, most of them would get ejected after a hundred million years (for comparison, the solar system is 50 times older). I don't have specific sources about the galactic core, but [this paper](_URL_0_) describes the stability of planets in globular clusters, which are supposed to be the cores of ancient galaxies that were later merged into the Milky Way." } ]

[ { "id": "corpus-322258", "score": 0.7387441396713257, "text": "Basic answer is no. Even if there could be a very marginal and unusual situation where there was a planet with a smidge more mass than the star in the system, they would orbit the centre of mass, which means they would both orbit around a point between them, rather than one around the other. The planet would have to be far, far more massive than the star for the centre of mass of the system to be inside the planet, so in that sense it definitely isn't possible.", "topk_rank": 0 }, { "id": "corpus-315834", "score": 0.7368126511573792, "text": "The short answer is that we don't know. We used to think that stars might very rarely have planets, and that the solar system was an outlier. Then we started to look for them, and we found planets almost everywhere; around big stars, around small stars, around almost every type of star. That doesn't mean that every star has plants, though. Stars in dense clusters might not allow planets to have stable orbits; other phenomena might limit planet formation as well. In the end, there are probably (speculation time) as many solar systems with a ton of planets (like us) as there are solar systems with no plantes.", "topk_rank": 1 }, { "id": "corpus-314625", "score": 0.7353809475898743, "text": "First things first: stars in a *galaxy* orbit around the galaxy, and their orbits can tell us about the matter distribution within the galaxy. The \"universe\" refers to everything that exists everywhere. Unlike visible matter, dark matter doesn't form clumps smaller than galactic scales. This means that in the neighborhood of the Solar System, the distribution of dark matter is pretty much uniform, and as a result it has no real effect on the orbits of planets. Within the Solar System, the dark matter density is also *extremely* low compared to the density of visible matter (which basically consists of the Sun). It *is* thought that dark matter particles may be captured by 3-body interactions with the Sun and Jupiter, but this will be an extremely negligible amount of mass compared to the Sun.", "topk_rank": 2 }, { "id": "corpus-262556", "score": 0.7352321147918701, "text": "It depends on the system, but many are far enough apart that each could have its own system of planets independent of the companion star. According to the [Wikipedia page](_URL_0_) on Alpha Centauri, the companion star wouldn't have a significant affect on the climate of a planet orbiting either star, and they orbit at a distance comparable to Uranus from our sun. The other star would move like a planet through the sky, but be brighter than the full moon. If the stars were closer they could interfere though. Also, wobble is not the only way we can determine if there are planets around a star. The new KEPLER observatory measures brightness changes from planetary transits.", "topk_rank": 3 }, { "id": "corpus-294642", "score": 0.7331497669219971, "text": "It depends. If the stars are very far apart, they may have completely separate habitable zones that don't overlap. But if they're close enough together that their habitable zones partly overlap, then any planets in one star's habitable zone will be in an orbit that comes pretty close to the other star. This will probably be gravitationally unstable, and the planet is unlikely to last long after the formation of the stellar system, if it forms at all.", "topk_rank": 4 }, { "id": "corpus-314881", "score": 0.7316893935203552, "text": "There are a few simplified cases: -the stars orbit each other closely and the planet orbits much farther away -the planet orbits one of the stars closely and then the three stars have their own orbit (Proxima Centauri b is like this) -the planet orbits two of the stars that are close to each other, and the other star is farther away Or there could be a chaotic many-body orbital system that may not be long-term stable", "topk_rank": 5 }, { "id": "corpus-294641", "score": 0.7295225858688354, "text": "Yes. If the stars are close together, they can have a combined habitable zone that goes around both of them. If they're far apart, they can each have their own habitable zone. In between, and there would be no habitable zone or the stars' gravity would make stable orbits in the habitable zone impossible.", "topk_rank": 6 }, { "id": "corpus-169597", "score": 0.726497232913971, "text": "Solar systems do not orbit the sun (star), they orbit the center-of-mass of the system. It just so happens that the center-of-mass is inside the star in most cases, because the star is so massive compared to the rest of the system. Same goes on the galactic scale. The galaxy has a center-of-mass that everything orbits around. The star in a solar system actually wobbles around this center-of-mass. Observing this wobble is one way that astronomers determine things about distant solar systems. More information here if you want to look into it, and a gif showing what I just described: _URL_0_", "topk_rank": 7 }, { "id": "corpus-322676", "score": 0.7263405323028564, "text": "Generally, the only stable orbits are nice elliptical orbits between two objects - or what is effectively two objects from their distance. So Alpha Centauri for instance consists of two stars of about equal mass to each other (and to the sun) orbiting each other at a distance equal to about the orbit of Saturn, plus a third star (Proxima Centauri) which is about 0.2 light-years away that orbits the other two stars. So similarly with planets, you will either have to orbit one star so closely that you basically only feel its gravity (the other stars only altering your orbit slightly), or you'll orbit the whole system from such a large distance that the three stars basically feel like one large star.", "topk_rank": 8 }, { "id": "corpus-319815", "score": 0.7254430055618286, "text": "It would be cool, but probably not. There are planets that orbit around two stars (aka a [binary star](_URL_1_)); these are known as [circumbinary planets](_URL_0_). However, they form an orbit outside the two stars, and since planetary bodies revolve around the planetary system's center of mass, both stars and the orbiting planets will orbit around their common center of mass. In addition, given the chaotic environment between a binary system, the most likely area for planet formation is outside the orbit of the two stars. However, there are mathematical models that suggests the plausibility of a figure-8 orbit (called a choreographic system because of its resemblance to dancing), but this has not been observed in space.", "topk_rank": 9 }, { "id": "corpus-82709", "score": 0.7252703905105591, "text": "Technically speaking, both the planet and the star orbit each other - they orbit the [barycenter](_URL_0_), the center of mass of both objects. However, since the star is usually much more massive than the planet, the planet's mass is usually negligible, and the barycenter is very close to the star's center of mass (which in most cases is inside the star itself). For a star to be considered to be orbiting the planet, the planet's mass needs to be larger than the star's - in which case the planet would likely become a star itself, resulting in a binary star system.", "topk_rank": 10 }, { "id": "corpus-308604", "score": 0.7247146368026733, "text": "No, because the cores of the planets are very dense and tightly bound together. There would, however, be significant losses of the envelope of the planet due to the heating, tidal effects, and solar wind.", "topk_rank": 11 }, { "id": "corpus-317942", "score": 0.7244274616241455, "text": "No. We are out in the \"suburbs\" of the Milky Way. Closer to the core, stars are closer together and generally larger, so much like cities things get more and more packed the closer to the center. There is speculation that very close to the center, stars are close enough to warm each other up, which might lead to supernovae triggering off a wavefront of exploding stars. Which would be very bright, until you died of radiation exposure.", "topk_rank": 12 }, { "id": "corpus-321038", "score": 0.7234002351760864, "text": "Probably rather normal; two stars orbiting each other (probably with one larger than the other) and then outside of that orbit some planets. Here is a good video describing the same sort of thing with Kepler-16b; - _URL_0_", "topk_rank": 13 }, { "id": "corpus-252133", "score": 0.7221320271492004, "text": "There is indeed thought to be a galactic \"goldilocks zone.\" & #x200B; While there is the obvious gravitational and cosmic ray maelstrom near the galactic center, the galactic \"suburbs\" the Sol system occupies also tends to have stars of the appropriate metallicity to allow for the right kind of rocky worlds to sustain a biosphere. (See Galactic Metallicity Gradient). & #x200B; In short, the galactic hub is thought to be too chaotic and energetic to provide the billions of years of calm planetary evolution Earth has enjoyed, while the galactic outskirts are thought to be too metal-poor.", "topk_rank": 14 }, { "id": "corpus-309447", "score": 0.7215572595596313, "text": "During simulations of the accretion disk of systems, we find the heavier elements such as metals tends to stay nearer the star while the lighter elements like gasses tend to coalesce further out. This is why the smaller but heavier element based planets like Earth and it's molten metallic core is towards the inner system, while the larger gas planets are not. There is an exception however, in that Massive Jupiter style planets may spiral inwards to find an equilibrium closer to the star. The increase of heat results in the planets becoming much larger than their already impressive beginnings.", "topk_rank": 15 }, { "id": "corpus-322061", "score": 0.7208380103111267, "text": "Although a pretty rare event, they can [collide](_URL_0_), or in other words, they can get arbitrarily close. The densest regions are the galactic nuclei as well as the cores of globular clusters, in which you can have thousands of stars per cubic parsec. The core of M 32, a satellite galaxy of the Andromeda galaxy has about 5000 stars per cubic parsec, which equals one star every 2,5 lightdays or every 66 billion kilometers.", "topk_rank": 16 }, { "id": "corpus-258056", "score": 0.7202339768409729, "text": "Yes, but it's not the stellar density that is the problem. Fact of the matter is that the galaxy is incredible sparse, even in the center (Except for the innermost couple of pc of course). The problem is all the dust in the center of the galaxy (dust = small silicate particles). Here's an extinction map of the Milky Way: _URL_0_ Center of the image is the center of the galaxy, the edges are 180 degrees away from center, so they basically connect. It's what we see around us. That is why we look towards the north/south galactic pole (vertically, up/down) when we want to look outside the galaxy.", "topk_rank": 17 }, { "id": "corpus-278836", "score": 0.7176218032836914, "text": "[It's *very* rare.](_URL_1_) We generally cannot view individual stars within other galaxies--[though there are exceptions](_URL_0_)--let alone find the planets which may orbit them. Only in the case of supernova are we made aware of an individual star outside our local group. Hopefully someone more knowledgeable on the topic stops by and gives you a better answer.", "topk_rank": 18 }, { "id": "corpus-300222", "score": 0.716587483882904, "text": "Conflicting information. In physics, an orbit is the gravitationally curved path of an object around a point in space. The planet being in the middle of the four stars suggests the stars are orbiting the planet instead, which gravitationally is not logical. I would suggest not mentioning any kind of orbit, but rather the four stars being locked as they are, while the planet is somehow exactly in the middle of them with equal pull from each star.", "topk_rank": 19 } ]

[ { "id": "corpus-325362", "score": 0.745317280292511, "text": "Matter can't move through the coordinates of spacetime with a velocity of c, but that speed limit does not apply to the changing geometry of spacetime itself. Inflation is not the spreading of matter through space, rather it's the early expansion of spacetime itself." } ]

[ { "id": "corpus-308730", "score": 0.7079834938049316, "text": "First, everything we know about the universe tells us that nothing can change position faster than the speed of light. If your question requires us to assume that you *can* change position faster than the speed of light, then your question cannot be answered. Second, the rate at which an object is receding from us due to expansion is *not* limited to the speed of light. This is because rather than the objects' position in space changing, space itself is expanding. There are many objects we can see that are receding at rates significantly above c. Third, there is no \"zone that would eventually be filled later\". The expansion of the universe isn't carrying a bunch of stuff out into some empty void. Rather, the entire universe is already filled with stuff and that stuff is just getting more and more spread out.", "topk_rank": 0 }, { "id": "corpus-126060", "score": 0.7077348232269287, "text": "So c only applies to things in space, not space itself. Space itself can, and did, expand much faster than c during its early formation. That's the reason the observable universe is smaller than the universe as a whole: anything beyond the observable universe is moving away from us at faster than c, meaning light emitted from any objects will never reach us.", "topk_rank": 1 }, { "id": "corpus-323239", "score": 0.7075042724609375, "text": "Since light travels at a finite speed and the universe hasn't existed forever, we can only see a finite-sized patch of the universe. From the CMB measurements we can deduce that the universe probably is much bigger than we patch we can observe, and there is no reason to assume that there are no galaxies in the unobservable parts (we assume that the universe looks approximately the same everywhere).", "topk_rank": 2 }, { "id": "corpus-165252", "score": 0.7068743705749512, "text": "There used to be a very good commenter on here named robotrollcall who answered questions like this all the time. I won't pretend to be an expert, but he stated [Here](_URL_0_) that \"The Big Bang did not occur at a point. There's no such thing as \"outside the universe.\" Based on our very best observations, it appears that the universe is now — and always has been — infinite in extent. It can't be circumnavigated, nor examined from outside. It just keeps going and going.", "topk_rank": 3 }, { "id": "corpus-304625", "score": 0.7068130970001221, "text": "We don't currently have the tools to talk about the *moment* of the big bang. But we can talk about things in terms of a limiting procedure. It turns out that, as far back as we can safely calculate things (which is quite close to the big bang), the Universe was never within its own Schwarzschild radius. In other words, no matter how dense it got, if you took a ball of radius r, counted up all the mass inside that ball, and calculated its Schwarzschild radius, it would never be greater than r (unless you had a ball so big that points at opposite ends would take longer than the age of the Universe to communicate with each other, but then the concept of a Schwarzschild radius doesn't make so much sense).", "topk_rank": 4 }, { "id": "corpus-661279", "score": 0.7058303356170654, "text": "[8] So scientists don't REALLY know the size of the universe because they say it's expanding, or to what we can see expanding. You see, because of the incredulous distances that span between places in the universe, light takes only so long to travel to places. So if we look into the sky right now, and we can see all those little specks of light, we're really seeing into the past because what we are seeing is the light that just hit the Earth. Because of this time delay, could the Universe really be finite?\n\nAnd on another note, if because of this time delay, we are seeing what the stars looked millions of years ago, could that mean that we are misjudging distances between the Earth and other stars that they are saying are millions of lightyears away? They don't KNOW where the stars are, they're just going off of the lights that they give off.\n\nAnd one more thing, why can't scientists make probes that capture video that we can view live rather than photos?", "topk_rank": 5 }, { "id": "corpus-833643", "score": 0.7057511210441589, "text": "Another way of framing the question for clarity:How much faster do the galaxies at the expanding edge of the universe travel, and how much does the relativity of time change from there to slower parts of the universe?", "topk_rank": 6 }, { "id": "corpus-166909", "score": 0.705531656742096, "text": "This question cannot be answered, because the premise is flawed. Nothing can go faster than the speed of light, so there is no answer to this.", "topk_rank": 7 }, { "id": "corpus-22338", "score": 0.7053489089012146, "text": "You could not have viewed the big bang from a distance, because it filled the entire universe, and occurred everywhere at the same time. It was an expansion *of* space, not an explosion *in* space.", "topk_rank": 8 }, { "id": "corpus-272211", "score": 0.705309271812439, "text": "Part of this is a misunderstanding of what the big bang is. The big bang isn't an explosion of matter coming from a point somewhere in the universe. It is that we have observed metric expansion of the universe. We can, with good confidence, trace back the history of the universe to almost a time (we usually call 0). If you extrapolate the extra 10^-20 seconds that we can't really say we know about (that's a conservative estimate you could push this as far back as the Planck time if you wanted to be confident) you get to a point where the metric becomes singular. That means that there is no defined distance between points at t=0. Which is very different to a black hole, which is a \"vacuum solution\" of GR, meaning that it is only valid when there is no matter other than at the singularity. The discontinuous (if the universe is infinite) expansion at t=0 is the \"big bang\".", "topk_rank": 9 }, { "id": "corpus-274348", "score": 0.7050343751907349, "text": "> for a period of time in our universe's history, photons somehow were unable to travel unimpeded This is called [recombination](_URL_1_). Before 380,000 years after the Big Bang the universe was so hot that all matter was ionized, and so photons couldn't travel far without bumping into protons. It wasn't dark as such - it was the same as the center of the sun. We don't see light from the center, we only see light from the surface, but if you dived to the center of the sun, it would feel very bright indeed. I don't know what is the limit on how \"bright\" an object could be, but there *is* a limit to how many photons could occupy a volume of space. If there are more photons within a given volume of space than its [critical density](_URL_0_), it will collapse into a black hole. Yes, photons participate in gravitational interactions, it's not just matter that gets to do all the cool stuff.", "topk_rank": 10 }, { "id": "corpus-168048", "score": 0.7047874331474304, "text": "Locally, nothing can move faster than light. You couldn't run that quick, no ship could fly that fast. But the expansion of space is different. Even though, locally, it's expanding pretty slowly, it's happening everywhere and all the time. When you look over vast differences it adds up to a total expansion rate that exceeds *c*.", "topk_rank": 11 }, { "id": "corpus-302182", "score": 0.7046734690666199, "text": "That's a great question, and if you figure out the answer you'll win a Nobel Prize for sure! Our understanding of physics breaks down in the early Universe. There are some theories, such as the [Eternal inflation](_URL_0_) theory, but those all remain very theoretical and hypothetical at this point.", "topk_rank": 12 }, { "id": "corpus-834616", "score": 0.7046716213226318, "text": "I understand the concept behind it, and I know that we are able to measure the fact that the Universe is growing, but I'm curious how it is scientifically possible for it to be ever expanding? This is a question I've always had but had never been answered.", "topk_rank": 13 }, { "id": "corpus-834950", "score": 0.7044438123703003, "text": "I was reading this paper from NASA Eagleworks, its talking about the possibilities of traveling at the speed of light or faster. As I understood this will be achieved by expanding space behind an object in some kind of bubble and contracting the space in front of it. Due to the expansion of space being faster than the speed of light the object in the bubble can move faster than the speed of light, Correct me if i am wrong.\n\nSo I ask you, what would happen if space is contracted at the point where an object is in the universe?\n\nWhat would be the effect on the object? Would it simply become denser and then re-establish its position in space? Would atom smash together causing something to happen? Would it create a black hole?\n\nEnlighten me :D\n\nThanks \n\nSource: ", "topk_rank": 14 }, { "id": "corpus-321424", "score": 0.7044223546981812, "text": "The universe expands at 74.2 km/s /Mpc (74 (kilometers per second) per megaparsec, a megaparsec is a very large unit of distance), not 74.2 km/s . That means that the rate of recession increases with distance, which is why light emitted by very distant stars will never reach us (there is a distance at which the rate of recession is greater than c.) edit: as point out below, because the hubble parameter is apparently decreasing with time, you can't trivially compute an event horizon from the hubble parameter.", "topk_rank": 15 }, { "id": "corpus-28478", "score": 0.7043682336807251, "text": "The universe is expanding. During the early expansion it was expanding much faster than the speed of light. The current [understanding of metric expansion in the universe](_URL_0_ ) is subject to some debate, particularly the effect of dark energy.", "topk_rank": 16 }, { "id": "corpus-833347", "score": 0.703906774520874, "text": "As i've read from previous answers, the expansion of the universe can be understood as the stretching of the distance between two otherwise stationary objects.\n\nBuf if this is the case, how can we percieve this expansion? Shouldn't all our measuring capabilities expand along with the universe? Shouldn't the meter expand?", "topk_rank": 17 }, { "id": "corpus-78337", "score": 0.7038771510124207, "text": "The rules didn't apply for that little cluster. It's better to call it the 'singularity'. Everything we know about physics breaks down in that little point. In fact, the word 'before' can't even be used here, because time didn't exist before the Big Bang. Time, as far as we are concerned, began *at* the Big Bang. So to answer your question - that singularity became matter and space itself. The Big Bang caused a very fast expansion of space. And today, space is still expanding. Quite fast. Often, that leads to another common question. [What is the universe expanding into?](_URL_0_) ____________ I want to link to a few videos that explain this quite well from Khan Academy. They're absolutely free and very well explained. A good place to start is here: [Big Bang Introduction](_URL_1_) and work your way across the videos (left column) to a bit of mind-bendiness: [A universe smaller than the observable universe](_URL_1_/v/a-universe-smaller-than-the-observable).", "topk_rank": 18 }, { "id": "corpus-259809", "score": 0.7036895751953125, "text": "The radius of the observable universe increases over time in both proper and co-moving distance, which are the two most common spatial coordinate systems. This really doesn't have much to do with the expansion of the universe. The distance to the edge of the observable universe (the particle horizon) is the distance beyond which light emitted at the big bang has not reached us yet. Even if the universe were not expanding (but had a finite age), there would still be a particle horizon.", "topk_rank": 19 } ]

[ { "id": "corpus-325363", "score": 0.6838176846504211, "text": "In the case of bread, it's starch crystallization as /u/steinbergergppro mentioned. In the case of fats (which go rancid), it's oxidation by air." } ]

[ { "id": "corpus-94095", "score": 0.6494019627571106, "text": "Mostly, it is because of degradation of food proteins. Different food stuffs have different protein contents. Meat, for example, has a protein named myoglobin which gives different colours to it depending on the temperature.", "topk_rank": 0 }, { "id": "corpus-80190", "score": 0.6492441296577454, "text": "Because the way things taste is actually mostly about how they smell. Being heated up makes a lot of compounds in your food more volatile, so the molecules are more likely to waft up from the food and make it into your smell receptors. Depending on how you warmed it up the milk may also be getting slightly cooked which would change the chemical composition slightly.", "topk_rank": 1 }, { "id": "corpus-119564", "score": 0.6491926908493042, "text": "A lot of the details in how food tastes comes from the smell. Increased temperature means the volatile compounds that our noses pick up are released more, so the smell (and corresponding flavor) is stronger. It also changes the texture of most food, which is also important.", "topk_rank": 2 }, { "id": "corpus-30832", "score": 0.6490309834480286, "text": "Many chemical reactions occur as food is cooked, including meat. These reactions change and enhance flavors, which is one of the reasons we cook food. By the way, one of these reactions, the Maillard reaction, occurs at 350 degrees fahrenheit, which is why so many recipes utilizing an oven call for the oven to be heated to 350 degrees.", "topk_rank": 3 }, { "id": "corpus-167821", "score": 0.6489573121070862, "text": "It has something to do with conditioning. The same is when you smell food and instantly become hungry.", "topk_rank": 4 }, { "id": "corpus-98002", "score": 0.6487440466880798, "text": "If you are allergic to something, your body overreacts when detecting certain chemicals. Chemicals such as proteins in food are denatured and change structure when cooked, so the body recognises it as a completely different substance.", "topk_rank": 5 }, { "id": "corpus-319424", "score": 0.6484518051147461, "text": "Initial water content, mostly. The material is trying to normalize to the humidity of the air that surrounds it. Chips and such have their water content greatly reduced by the cooking method. As the moisture creeps back in, the materials become less crunchy. Bread starts with a pretty high water content and loses moisture to the surrounding air to equalize. Bread can be a little tricky, because some breads contain materials that maintain moisture pretty well. Basic french bread (flour, water, salt, yeast) goes stale very rapidly. Breads that contain oil, egg, extra sugar or honey can keep much longer.", "topk_rank": 6 }, { "id": "corpus-20168", "score": 0.6484286189079285, "text": "Imagine an apple. Large and juicy, full of flavour and nutrients growing on the branch. Think of it ripening, at some point it's at it's perfect levels of sweetness, crunch, and juiciness. Delicious right? Same with a rare steak. If you let it go too long, it loses the flavour. Loses the moisture content, loses it's texture until it's a uniform piece of dry and bland meat. I work in a kitchen. Almost every well done steak goes out with a request for ketchup.", "topk_rank": 7 }, { "id": "corpus-189771", "score": 0.6484177708625793, "text": "Usually because whatever is in the jar got between the threading at the top of the jar and the lid, dried up and got sticky. Or the jar got cold and the metal lid contracted.", "topk_rank": 8 }, { "id": "corpus-179929", "score": 0.6483420729637146, "text": "The air inside has a finite amount of humidity. Whether pulling moisture from the food or providing it, the interaction is pretty short-lived. When left open, the air is relatively endless, and with it the ability to pull or provide moisture.", "topk_rank": 9 }, { "id": "corpus-162224", "score": 0.648144543170929, "text": "Cured foods are highly dehydrated, using salts, heating, or other processes. That lack of water keeps bacteria from growing on cured meats, making them able to last an extremely long time, especially when stored in sealed packaging.", "topk_rank": 10 }, { "id": "corpus-55518", "score": 0.6481410264968872, "text": "Ice crystals form and cut through food. This can severely change the texture for example fruit comes out mushy because the cell walls are ruptured and the stored liquid has been released", "topk_rank": 11 }, { "id": "corpus-164876", "score": 0.648049533367157, "text": "Fruit ripens after it gets picked because of chemical processes that were already in motion. Ripening can be forced through chemical means with ethylene or acetylene gas.", "topk_rank": 12 }, { "id": "corpus-128170", "score": 0.6479781866073608, "text": "There's a technique called [Titration](_URL_0_). Basically, the food is dissolved into a dilution, and then this dilution is analysed via chemical reactions. But don't ask me how exactly this works. :) Source: My mother is an analytical chemist.", "topk_rank": 13 }, { "id": "corpus-2013028", "score": 0.6477447152137756, "text": "Is there a scientific reason as to why the smell of fast food seems to linger longer than the smells from other foods, especially in confined spaces such as airplanes or cars? \n\n[edit] Holy cow this blew up much more than I expected, thanks for the informative responses!", "topk_rank": 14 }, { "id": "corpus-245305", "score": 0.647580623626709, "text": "Cut fruits and vegetables turn brown due to the oxidation of polyphenols by an enzyme polyphenol oxidase, which is released when cells are cut. The rate of browning depends on various factors, such as the phenolic content of the food, the polyphenol oxidase content of the food, the oxygen content of the air, the temperature, the pH of the food, and the presence of antioxidants such as vitamin C. I would hypothesize that these factors are at play, hopefully someone can find data to support which factor is dominant in this case. Source: MS in food science.", "topk_rank": 15 }, { "id": "corpus-2269789", "score": 0.6474756002426147, "text": "I hate cooking. I hate to take care of all the nutritional elements that may be superfluous or deficient. I hate to check all the harmful substances in foods. I hate to keep track of foods in the refrigerator to eat them before they go bad.\n\nI want to eat one instant food and forget about it. Now if only there is such food that contains all nutrients humans need, and does not contain any harmful substances, and does not need cooking, and does not go bad (dried or frozen). I don't care about the taste.", "topk_rank": 16 }, { "id": "corpus-101463", "score": 0.6474530100822449, "text": "There is a protective coating that occurs naturally for farm-fresh eggs or is added in the process onto those eggs sold in most major stores which closes up the porous shell which lets in all the bad things that cause spoilage (ex. bacteria). When you boil the eggs, it degrades and many times completely eliminates this coating shortening the shelf life of the egg. Source: _URL_0_", "topk_rank": 17 }, { "id": "corpus-166945", "score": 0.647376298904419, "text": "The chemical which makes food spicy is called capsaicin. Capsaicin is an irritant. When you eat spicy food some of it will become airborne and this irritates the lining of your nose. Your body makes the nose lining produce more mucus in order to wash off the capsaicin. Source: I'm a medical student", "topk_rank": 18 }, { "id": "corpus-29111", "score": 0.6469720005989075, "text": "There are various ways of preserving food: salt (meat jerky), sugar (candied fruits), acid (pickles), heat (sundried tomatoes, smoked foods), and cold (frozen and refrigerated foods). Preservation of food prevents the original food items from living and prevents bad things from living off of it. The roof of your mouth is alive and does not want to be preserved. Exposing it to too much of any of those mentioned above will make the roof of your mouth unhappy.", "topk_rank": 19 } ]

[ { "id": "corpus-325364", "score": 0.7828903794288635, "text": "Whilst friction slows down your acceleration, you do intrinsically need energy to move in the first place, even with no friction, based on how much mass you have and how fast you're going. Special Relativity states that the amount of energy you need increases exponentially to infinity as you approach the speed of light - unless you have no mass (like light itself!), in which case you can only travel at the speed of light." } ]

[ { "id": "corpus-292120", "score": 0.7435258626937866, "text": "The rule of relativity states that nothing can move *through* space faster than *c*, but you are correct that space itself can expand away from us faster than *c*. This is what leads to the \"cosmic horizon\": A point sufficiently far away such that no information past that point can ever reach us. As for your title question, a lot of people might chime in and assert that relativity shows us that there is no preferred reference frame, so it is meaningless to state that something is \"absolutely still\" relative to open space. However, this is actually not true. There *is* a \"preferred\" reference frame (at least locally): the cosmic microwave background radiation (CMB) reference frame.", "topk_rank": 0 }, { "id": "corpus-52025", "score": 0.7433353662490845, "text": "[Verisasitum](_URL_0_) has a great video explaining why something like this, as well as other proposed systems, can't exceed the speed of light.", "topk_rank": 1 }, { "id": "corpus-151595", "score": 0.743155300617218, "text": "Nothing can travel faster than light. It's the absolutely speed limit of the Universe. So it's terrifically difficult to answer this question.", "topk_rank": 2 }, { "id": "corpus-183431", "score": 0.7429893612861633, "text": "Simply put, massive amounts of matter didn't move faster than light in every direction. The matter stayed put in the space it was in, but space itself expanded and there is no speed limit on the expansion of space (as far as we know), only on the things that move through space. Think of it like a lemon poppy seed loaf sprinkled through with little poppy seeds. When it goes in the oven, it's a small lump of dough. Let the poppy seeds be matter sprinkled through the universe. The dough is space. During baking, the dough expands but the seeds stay the same. As the dough rises (space expands), the seeds (matter) get farther apart, but each seed is still surrounded by the exact same dough as before, it's just that there's much more dough. In the case of the universe, the dough is able to rise at a ridiculous rate of speed.", "topk_rank": 3 }, { "id": "corpus-301426", "score": 0.7429705262184143, "text": "No. The way you are calculating accelerations is only correct in the non-relativistic limit of speeds substantially below the speed of light. It is also physically unrealistic, because you only find the acceleration due to gravity has a nearly uniform value near the surface of a large spherical object (if you had an object moving at c/10, it would not stay near the surface of the Sun very long; it could travel the Earth-Sun distance in around an hour and a half). But let's imagine that you somehow filled space with a gravitational field that accelerated low speed objects at 274 m/s^2. As the object's speed increased, you would have to modify your equations of motion to be consistent with relativity, and you would find that the speed of the object would not increase as rapidly, and would never exceed the speed of light.", "topk_rank": 4 }, { "id": "corpus-170302", "score": 0.7428324222564697, "text": "Space isn't sitting still during those 13.8 billion years. It's expanding. Not only is it expanding, it's expanding faster and faster. Imagine if you see a car in distance. You use a laser to figure out the distance is 100meters. You know you can travel at rate of 1m/s. You estimate that you can reach the car in 100seconds. So you start moving but the car is moving away as well. And not only is it moving away, it's accelerating.", "topk_rank": 5 }, { "id": "corpus-166812", "score": 0.7425615787506104, "text": "The \"speed limit\" of *c* (speed of light) is in reference to movement *through* space. Nothing about inflation theory suggests violation of that. In other words, while space itself may have been expanding unfathomably fast, nothing within the universe itself was moving that fast.", "topk_rank": 6 }, { "id": "corpus-293089", "score": 0.7425364851951599, "text": "There is (more or less) no friction in space. This seems obvious but videogames and movies almost always have the ships constantly burning their rockets just to maintain a steady speed. Fortunately it does not work that way. Voyager 1 started out on top of a fairly big rocket and did a rare series of gravity assists. It now has enough speed to leave the solar system and never return. The plutonium on board is used solely to power the antennas and remaining instruments.", "topk_rank": 7 }, { "id": "corpus-288624", "score": 0.7423139214515686, "text": "If you have some limited maximum acceleration and deceleration, the way you describe would be fastest. Otherwise it would be faster to continuously accelerate all the way there and then jam on the deceleration to the max at the last second, similar to what you are describing. This would be very uncomfortable. Fortunately, [the most comfortable way to do relativistic space travel](_URL_0_) was recently worked out; the low-velocity way is to do it with constant jerk, but it gets more complicated as you go fast.", "topk_rank": 8 }, { "id": "corpus-324806", "score": 0.7423030734062195, "text": "Relative to what? There's no such thing as absolute speed. To high-energy cosmic particles we are moving very close to the speed of light indeed.", "topk_rank": 9 }, { "id": "corpus-325353", "score": 0.7422431111335754, "text": "It's the speed *through* space which is limited by 'c', not the speed of light itself. Imagine you're at an airport. The maximum speed that you can move with your heavy suitcase is 10 mph. Now, you get onto the moving walkway... you can walk at 20 mph, with the aid of the belt. Are you exceeding the 10 mph limit? No, because you're only *walking* at 10 mph... it's the ground that's carrying you along, and making your walking speed look faster than it is. This is how it is; moving walkway = expansion of the Universe. The Universe is just the floor that the galaxies move around on, but the floor moves.", "topk_rank": 10 }, { "id": "corpus-46836", "score": 0.7421467900276184, "text": "Matter isn't flying apart; space itself is expanding. So the speed of light doesn't come into it. Think of it like a couple of ants an inch or so apart on the surface of a balloon. Even if they crawl apart, they can only each move at the speed of Ant. But if you blow up the balloon itself really fast, even if they don't move they can still end up way more apart than an inch (and quite probably much further than they could have gone at the speed of Ant in the same amount of time). And each one will think that the other is moving away very fast. (Only they won't, because they're ants. And provided the balloon doesn't burst. But you get the idea.)", "topk_rank": 11 }, { "id": "corpus-169004", "score": 0.7421172857284546, "text": "Relativity doesn't work that way. You wouldn't be able to walk forward on the ship. If you were traveling AT the speed of light, it would take an infinitely long period of time to move forward any distance whatsoever, effectively preventing you from moving forward at all.", "topk_rank": 12 }, { "id": "corpus-166928", "score": 0.742027759552002, "text": "Nothing can move faster than light in relation to space-time, however no such limit is placed on space-time itself. Basically, space-time can expand at a rate faster than light, just not the objects within it.", "topk_rank": 13 }, { "id": "corpus-167872", "score": 0.7418398857116699, "text": "Our current understanding of the universe says that you cannot travel faster then the speed of light. You might as well ask, if driving in reverse decreases the mileage on your car.", "topk_rank": 14 }, { "id": "corpus-73145", "score": 0.7416329979896545, "text": "As you accelerate, you need more and more fuel the faster you want to go. This amount of fuel (or energy) gets higher and higher as you approach high speeds, and the amount of energy needed to achieve the speed of light approaches infinity. Also, not specifically related to the speed of light, but to the acceleration in general: you would need fuel to carry the fuel itself, which makes it more difficult to accelerate, and this can be overcome by bringing more fuel, which brings in more weight, which requires more fuel...", "topk_rank": 15 }, { "id": "corpus-291978", "score": 0.7414175271987915, "text": "There is no absolute velocity that could have such an impact. We're moving at nearly the speed of light *now*, in some reference frame, and as you can clearly tell we're not experiencing any negative side-effects. [edit] For reference, you would only need to undergo 1g acceleration for around 2.5 years (your time) in order to reach 99% the speed of light relative to your original reference frame.", "topk_rank": 16 }, { "id": "corpus-108148", "score": 0.7411773204803467, "text": "An actual ELI5: Light travels as fast as it does because it has no mass, therefore nothing can else can travel as fast as light.", "topk_rank": 17 }, { "id": "corpus-115137", "score": 0.7411108016967773, "text": "You can't travel at the speed of light. So any question asking \"what would happen if you could travel at the speed of light\" is like asking \"what does physics say would happen in a situation that physics says can't possibly happen\"", "topk_rank": 18 }, { "id": "corpus-834268", "score": 0.7410695552825928, "text": "I understand that the speed of light is a threshold that cannot be surpassed. Are there any objects in space we know of that can closely compare?", "topk_rank": 19 } ]

[ { "id": "corpus-325366", "score": 0.7237485647201538, "text": "This would require interferometry on a massive scale that we don't yet have the technology to implement (but it's not impossible). To see in the the optical band with 1000 km resolution from 100 lightyears away (just spitballing parameters here), you'd need a telescope about 5000 km wide. This is not feasible, but an array of telescopes could do the job (the Very Long Baseline Array already does this for radio astronomy). This array of telescopes could either span the surface of the Earth (while being close enough to point at the same thing), or could be in space." } ]

[ { "id": "corpus-290616", "score": 0.6871311068534851, "text": "Not yet, currently the best we can do is see the accretion disks around them and [the orbits of stars around Sag A*](_URL_0_). There is an ongoing project called the Event Horizon Telescope which is trying to image the event horizon of Sag A* directly but even when it succeeds it will look like a darky fuzzy area on top of a bright fuzzy area.", "topk_rank": 0 }, { "id": "corpus-302350", "score": 0.6870500445365906, "text": "Depends on the lens and where the planets are when you take the picture. For a good photograph I'd suggest waiting until the planets are within 30 degrees so if you sent a probe to the sun with a lens that could see in a 30 degree cone, you could do it. The distance the probe would have to go would be about 1 au... Thiss event will happen again in the 29th century. But you could also just use a super (super) wide angle lens and go slightly above the plane of the solar system and take it from just next to earth. Sort of. In any case, the picture wouldn't be very interesting to look at. The planets would be pretty much nonexistent in the photographs.", "topk_rank": 1 }, { "id": "corpus-1190772", "score": 0.6868881583213806, "text": "After just buying some decent bins my interest in Astronomy has been tweaked again. Now I’m starting to look for a scope. \nAs stated in title I’m looking for impeccable optical quality and for detailed planetary viewing how far do I have go lens wise?\n\nI want to put the major expenditure into the optics yet still have a good solid easily controlled reliable mount to be used from a sitting position. \n\nLocation is north central Toronto Canada. \nAs far as budget goes the old “whatever it takes” applies here but I think about 5k would be max. \n\nI’m going to spend a little time checking this all out but suggestions for the best viable choices and anything I might have missed would be greatly appreciated. \n\nThanks.", "topk_rank": 2 }, { "id": "corpus-1902504", "score": 0.6864750981330872, "text": "I got a Celestron astromaster 130eq for Christmas, I’ve been stargazing with a refractor for a while and I think I set up my new one correctly but I’m not sure how to get decent images, for example, when I try to look at stars it just appears as a blurry circle with a cross in the middle which I’m assuming is a shadow from the mirrors mount, I’m not sure if there is a way around this but if anyone knows how to use this telescope to look at planets, stars, galaxies and the moon etc it would be very appreciated.", "topk_rank": 3 }, { "id": "corpus-321588", "score": 0.68643718957901, "text": "[Solar telescopes](_URL_0_) have existed in one form or another for a long time. The simplest way to observe the Sun with a telescope is to project the image onto some surface, e.g. paper or a wall, and view it there. For more complex arrangements, filters are indeed used. Many amateur astronomical societies have solar telescopes with special filters (often the [H-alpha](_URL_1_) emission line, which brings out many features in the Sun), which are often made available for viewing during solar eclipses. There are also several research telescopes built specifically for looking at the Sun, which are mentioned in the article linked at the start of my comment.", "topk_rank": 4 }, { "id": "corpus-294734", "score": 0.6864006519317627, "text": "Our detection methods don't work well for systems that look like our solar system. We don't know yet. What we know for sure: There are many systems that look completely different. Planets much closer to the star, much more distant, inner gas planets and outer rocky planets, planets in double star systems, planets as hot as some stars, ... * Transits and related methods are more likely for planets near the star. We found many systems with planets very close to the star - often closer than Mercury. * Radial velocity measurements work better for heavy planets close to the star. We found many systems with that. Imagine Jupiter, but closer to the Sun than Mercury. * Direct imaging works best for very large planets with a very large separation to the parent star, much larger than the planets in our system. * Microlensing and other approaches don't find enough for good statistical analyses.", "topk_rank": 5 }, { "id": "corpus-72803", "score": 0.6863536238670349, "text": "The thing about galaxies (clusters of stars) is that they are by definition very bright objects. And we detect exoplanets typically by pointing a telescope at a star and waiting for something to pass between the star and us. Any planet further than us from the sun will never pass between us and the sun - and will not give off any light. At this point, you're talking about a needle in a haystack a very very very very long ways away.", "topk_rank": 6 }, { "id": "corpus-278420", "score": 0.6863343715667725, "text": "This is essentially what radio telescopes do. Obviously it's not the same technology as with optical photography. The top few images [here](_URL_2_) are the Milky Way at different radio frequencies.", "topk_rank": 7 }, { "id": "corpus-1190285", "score": 0.6863301396369934, "text": "This is for backyard astronomy- I have a 10\" dob and obviously get great views of Saturn and Jupiter- but I would like to track down some other objects without having to drive 2 hours away to escape city lights. Is there anything bright enough you can recommend I look for? Astronomy books haven't been much help since they all assume minimal light pollution. Also please suggest any recommended eyepiece/filters. Right now I have a decent 3x barlow, a 6mm, and a 25mm (1.25\").", "topk_rank": 8 }, { "id": "corpus-242449", "score": 0.6863195896148682, "text": "If you could build a [focimeter](_URL_0_) using the laser, then yes!", "topk_rank": 9 }, { "id": "corpus-120509", "score": 0.6849768161773682, "text": "There is a limit, called the \"[diffraction limit](_URL_0_ )\" which limits how small an object a perfect telescope could detect. If you make the objective bigger, you can see more detail, but there is still a limit. It also depends on the wavelength, so you can also search in a different wavelength. There are radio telescopes that operate on very large scales to resolve very small objects.", "topk_rank": 10 }, { "id": "corpus-2446634", "score": 0.6847528219223022, "text": "When I was a kid my grandfather gave me a telescope. It's mostly sat in my bedroom for the past decade, the only astronomy I've done with it is to look at the Moon. When fully zoomed in the Moon just about filled the entire view from the telescope. I've always wanted to observe Jupiter and Saturn properly, would it be possible with this telescope? It's marked 15X to 60X 60mm zoom. Here's some pictures of it. I have no idea how old it is, could be anything from the 1960s to the 1980s.", "topk_rank": 11 }, { "id": "corpus-1037786", "score": 0.6841967105865479, "text": "Hi /r/telescopes! \n\nI did not prepare early enough for Mercury's sun transit by getting a solar filter and was wondering if it's feasible to project an image of the sun through an 8\" SCT. \n\nI read that it's not a good idea to do this -- at least for long -- since the eyepiece and other elements of the telescope will get destructively hot. I don't want to risk any damage and would like to err on the side of caution. Can you guys corroborate this information? \n\nAre there any modifications that would make this possible? \n\nThanks!", "topk_rank": 12 }, { "id": "corpus-289008", "score": 0.6841556429862976, "text": "Yes. And we've done it before, and are about to do it again. It's called the [NEOWISE](_URL_0_) project, and will be restarted some time in 2014, using infrared detection to find near-Earth objects. ( of course, the sticking point here is \"EVERY\" asteroid - NEOWISE will have to actually be pointing at the asteroid to see it, and even then, something might get in the way, or something might malfunction, etc. But the base principal you're asking about has been done before. )", "topk_rank": 13 }, { "id": "corpus-324594", "score": 0.684084415435791, "text": "The [Chromoscope](_URL_0_) may be relevant to your interests. It lets you visualize the sky in various wavelengths.", "topk_rank": 14 }, { "id": "corpus-168453", "score": 0.683988094329834, "text": "There's almost no light that reflects off them that reaches us. Thus even with our best telescopes, we can't get any image of their surface. Typically, planets outside our solar system are discovered by watching fluctuations in the light from the star they orbit. Astronomers can calculate the approximate orbit and size of the planet, but there's no way to actually know what the surface has on it with current technology.", "topk_rank": 15 }, { "id": "corpus-1190557", "score": 0.6839504241943359, "text": "Basically I am wondering if I buy an astrophotography telescope, are they just bad at using as visual telescopes?\n\nI am looking at these for my first telescope with the fore thought of getting into astrophotography down the road. I am wondering yours all thoughts. My very max budget is ... man, maybe 450 very top max at this time. I'd like to stay within $350 range though for just the scope.\n\n\n\n\n\n\n\n\n\nMy goals are to next buy a camera and/or lenses to take some short shots. After that I would like to start getting into astrophotography, so I'd be saving up for a mount, guide and all what have you. I just don't want to \"screw up\" right off the bat and I don't know if you can mount dob's on a guide. All the astrophoto tele's I see are not generally netwonian(I guess?).\n\nStorage is a bit of an issue but I can clean out half a closet.\n\nSo Astrophotos stick says \" There are a lot of different factors in what makes a telescope good for astrophotography – before settling on an OTA or a mount you need to know what to expect and decide what your goals are. A planetary setup may be completely different from a DSO setup and vice-versa, indeed a lot of us have a scope for each. Planets benefit from larger apertures but can be done with almost any telescope to some extent, DSOs benefit from fast focal ratios and require accurate tracking due to their faintness and subsequently longer exposure times. It can be difficult to find an entry-level setup that can do both well.\"\n\nTL;DR - Very down the road I wouldn't mind doing DSO photos but don't know if those are usable as planetary ones? I know rigs are better at some things than others but end of the day my over all question is if there is one that is kind of decent at DSO and planetary, visually and down the road .. photographically?\n\nI appreciate any feedback. Thank you.", "topk_rank": 16 }, { "id": "corpus-181129", "score": 0.6839051246643066, "text": "Diffraction's your biggest enemy here. Literally. Light spreads out, so you need a massively wide telescope to differentiate between two nearby points. If your telescope is any smaller, those two points will blur into one, and it becomes physically impossible to tell them apart. Lord Rayleigh proved that the diameter of a telescope limited solely by diffraction is roughly the distance to the object, multiplied by the wavelength of light, divided by the radius of the object. Let's plug in some numbers, and give a rough idea. Visible light has a wavelength of 400 to 700 nanometers, so let's call it 500 nanometers. The largest dinosaur is roughly 40m wide, but Alpha Centauri, the nearest star to Earth, is 4.25 light years away. And so, our hypothetically perfect telescope needs to be more than 610,000km in diameter to pick out the rough outline of a dinosaur. That's bigger than the distance between Earth and the Moon.", "topk_rank": 17 }, { "id": "corpus-319987", "score": 0.6834816932678223, "text": "There is [a limit](_URL_0_) to how far we can zoom in. The angular resolution depends on the size of the telescope and on the wavelength of light used.", "topk_rank": 18 }, { "id": "corpus-309630", "score": 0.683432400226593, "text": "Yes, what limits this is the [diffraction limit](_URL_0_). The basic idea behind diffraction is how well your imaging system can resolve two closely spaced points. The diffraction limit is set by the size of your camera's aperture (entrance pupil) and the wavelength of the light you're looking at. This is one reason that scientific grade telescopes have very large mirrors - bigger mirrors mean better resolution. **Back of the envelope calculation:** A 1m rock located at the same distance as Andromeda (2.4 x 10^22 m) subtends an angle of about 10^-22 radians. from the equation for angular resolution: (500nm * 1.22)/(10^-23 ) ~D So D~10^17 m You would need a telescope with a diameter of roughly 10^14 km, or about 650 times the distance from the earth to the sun. ~~(If my math is correct, but in truth I wasn't being terribly careful)~~. Peer review shows my calculation is fine. **Edit:** It's not impossible, just obscenely unfeasible.", "topk_rank": 19 } ]

[ { "id": "corpus-325367", "score": 0.8412437438964844, "text": "Yes. Every planet has seasons to some extent. For Mars, see here: _URL_0_ The moon is almost perfectly lined up in its orbit, the tilt is less than two degrees. Coupled with the lack of atmosphere, the Moon doesn't have seasons that mean anything. There needs to be an atmosphere for even larger tilts to have meaning, which is limiting for some planets. On the extreme end, Uranus has a tilt of 98 degrees. So it has seasons that are far more extreme than anywhere else, with 42 years of sun at a pole, dark on the other. Google can get you details on this. Most planets can be said to have four seasons, but its important to note that we humans picked four points to call seasons for biological reasons, not cosmological ones." } ]

[ { "id": "corpus-260788", "score": 0.7744197845458984, "text": "There is no reason there couldn't be seasons, because the seasons have nothing to do with the rotation rate of the moon. On Earth, the seasons are a result of the tilt of the Earth's axis relative to its orbit around the Sun. A tidally locked moon will generally align its spin axis with that of its planet. If the planetary spin axis was similar to Earth's, the moon would experience seasons similar to those on Earth. Even if there isn't enough time to align the spin and orbital axis, the moon's orbital axis would still produce seasons if it was similar to Earth's relative to the Sun.", "topk_rank": 0 }, { "id": "corpus-308190", "score": 0.7599406838417053, "text": "No. Seasons exist because the axis of rotation of the earth isn't \"vertical\" to the earth's orbit around the sun, and the axis doesn't really change. So for large parts of the orbit, the northern hemisphere points slightly away from the sun, and gets less sunlight. Half a year later, the sun has moved \"around\" the earth (relatively speaking), and the southern hemisphere now points away. The moon, however, moves \"around\" the earth (also relatively speaking) once a month, so earth's lunar \"seasons\" are about a week long.", "topk_rank": 1 }, { "id": "corpus-317349", "score": 0.7455968260765076, "text": "Seasons come about from the tilt of the Earth and it's orientation to Sol during it's orbit. This is why in North America, we're celebrating Winter right now while Australia is celebrating Summer. The Northern hemisphere is receiving less light than the Southern hemisphere. The same thing happens on Mars. However, season lengths vary from Earth's seasons. Mars has a longer year than Earth does, and it's tilt is different than from Earth. Because of this, one of its seasons lasts about 7 months (Spring for the north, Autumn for the south). The moon, however, has nearly a negligible tilt -- about 1.5*. On the moon, it's eternally one season. However, other moons, such as the moons of Jupiter and Saturn, are trickier. They orbit their respective parent planet...and they get lost behind their parent planet during their orbit. So the seasons of those moons are a bit...eccentric, to say the least.", "topk_rank": 2 }, { "id": "corpus-292174", "score": 0.7041584849357605, "text": "It has been hypothesized that the seasonality (length in the order of millions of years) of large impact events on Earth and in the inner solar system might be caused by the back-and-forth dipping of the Sun through the central plane of the Galactic disc, which, being denser, might disrupt the built up matter at the outer edges of the solar system, sending it careening towards the central parts. That's really the closest I can think of to Galactic seasons. Really, otherwise, the distances to everything else are just too great to have something like weather effects on the Sun or on the planets.", "topk_rank": 3 }, { "id": "corpus-152576", "score": 0.6878417730331421, "text": "Lunar calendars give \"preferential treatment\" to the moon and Gregorian calendars give preferential treatment to the sun. It's hard to find some sort of consistent way to balance both in a calendar so what happens in a solar/Gregorian calendar is that the months aren't exactly a lunar cycle but the year is very very very close to a trip around the sun. In a lunar calendar, the months match up to the moon cycles, but the seasons shift since it's off from the spin around the sun. My understanding is that some lunar calendars make up for this by having a short month that resolves the remainder of the sun trip.", "topk_rank": 4 }, { "id": "corpus-1335875", "score": 0.6877921223640442, "text": "The Western world has four seasons, from the Gregorian calendar. These are based on the ratio of daylight/nighttime: Summer and Winter begin on the *solstice,* the longest and shortest days of the year respectively, while Spring and Fall begin on the *equinox,* when the day and night share equal amounts of time.\n\nHowever, although most calendars in the Indian subcontinent (\"Hindu calendars\") are *solar* calendars, meaning a year is based on the cycle of the earth about the sun and has 365 days, they typically use *six* seasons. Each season has two months, and two of them coincide with the *rainy and dry seasons.* This is related to the fact that India experiences *monsoons,* and farmers plan their crops around these. I find this interesting because the major difference with the Gregorian calendar is based on differences with India's unique climate.\n\nSo here's my question:\n\nIs there a thorough classification of different calendar systems and how they choose to divide the seasons, based on their environmental differences?\n\nI'd also be interested in how astrological beliefs, and the distinction between lunar/solar affects these seasons.", "topk_rank": 5 }, { "id": "corpus-323896", "score": 0.6869441270828247, "text": "The Earth's wobble (precession of the equinoxes) doesn't cause the seasons. The seasons are due to the axial tilt and the orbit of the Sun. \"Seasons\" isn't an astronomical term. Any planet whose axis of rotation is tilted with respect to its orbital plane will have solstices and equinoxes. If you wanted to, you could define four seasons between those solstices and equinoxes. That's not quite the same thing as \"the four seasons we experience\", though, since the seasons (in terms of weather and biosphere) don't have to follow the equinoxes and solstices. Also, a planet with only very slight axial tilt will have only very slight changes in insolation throughout the year.", "topk_rank": 6 }, { "id": "corpus-320930", "score": 0.6858107447624207, "text": "Yes. The difference to a planet and moon system is not a sharp dividing line, however. We know from exoplanet observations (mainly transits) that these systems have to be rare close to the stars, but they could be more common for larger separations.", "topk_rank": 7 }, { "id": "corpus-324162", "score": 0.684512734413147, "text": "Essentially yes. But none of their orbits are perfectly level. If we define level as the plane of the sun's equator, then _URL_0_ tells you by how much each planet is off level, \"Inclination to Sun's Equator\". Space Trivia Point: The moon's orbit around the earth is not level either, at least not in the same plane as the earth's orbit around the sun. For if it were, we would have eclipses twice a month. Do you see why that would be the case?", "topk_rank": 8 }, { "id": "corpus-312891", "score": 0.6834614276885986, "text": "A planet with no axis tilt would still have normal latitudinal temperature variations, and in fact they would be more distinctive. The tropics would be always warm, the temperate zones always \"fall or spring temperature\" and the poles always cold. In a nearly circular orbit there would be no seasons, but in an elliptical orbit there could still be seasons, just from the planet being closer to the sun at some points and farther away at another point (note that this is NOT the cause of seasons on Earth). We don't really need to study other planets to know all this in general terms, because it isn't terribly complicated physics. Still, it would be interesting to see it in action. I don't know any details about that part.", "topk_rank": 9 }, { "id": "corpus-317611", "score": 0.6829429268836975, "text": "Yes, [approximately half](_URL_0_) of the moons in our solar system are tidally locked to their parent planet, meaning they only ever show one side to that planet.", "topk_rank": 10 }, { "id": "corpus-268542", "score": 0.6821991801261902, "text": "The work of [Miguel and Brunini (2010)](_URL_1_) suggests that the distribution of axial tilts for terrestrial planets *at formation* could well be isotropic (evenly distributed in all directions), and that planetary rotation rates tend to lie between 10 and 10000 hours. Post-formation, planets can have their axial tilt and rotation rate changed by a number of things including tides and perturbations from other planets. My guess is that we have four seasons by definition, based on having two solstices and two equinoxes. We humans could just as easily have defined three seasons, however the solstices and equinoxes are easily observable events that divide the year up pretty well. A planet will have two solstices and two equinoxes for any non-zero axial tilt. You might want to [askHistorians](_URL_0_) for how the seasons got defined.", "topk_rank": 11 }, { "id": "corpus-101147", "score": 0.6802622079849243, "text": "Aside from tides, IIRC the moon influences the earth's axial tilt, if it disappeared it would affect the seasons.", "topk_rank": 12 }, { "id": "corpus-317794", "score": 0.6786072254180908, "text": "This [video](_URL_0_) may help you understand the mechanics a bit better. The north pole and south pole remain pointed at fixed points in space year round, while the planet circles the sun on a different plane. This means the orbit naturally creates the same seasons year round. If the poles were pointing directly perpendicular to the plane of orbit, we'd have only one season year round, if they were pointing directly at the sun on the two equinoxes, we'd have really crazy swings in seasons year round.", "topk_rank": 13 }, { "id": "corpus-278765", "score": 0.6784199476242065, "text": "[Seasons on Pluto are a bit different than on Earth](_URL_0_) because the temperature is mainly controlled by the distance to the sun rather than the angle of the axial tilt with respect to the sun. Pluto reached the hottest part of its orbit around 1990, and is currently approaching the summer solstice in its Northern hemisphere.", "topk_rank": 14 }, { "id": "corpus-64736", "score": 0.6781272888183594, "text": "The moon is tilted with respect to the earth's orbit around the sun, and only truly comes between the earth and sun for about a month twice a year, a time know as eclipse season. Eclipse season is currently in February and August, and will shift slightly from year to year.", "topk_rank": 15 }, { "id": "corpus-309810", "score": 0.6764470338821411, "text": "It fluctuates, but of course Earth's year isn't relevant to changes on the sun, nor are these fluctuations relevant to seasons on earth. You didn't ask this, but your question phrasing makes me think you believe the seasons are related to our distance from the sun. You realize that's not technically accurate right? It's about which direction our axis is tilted in, relative to our orbit. The earth is actually closest to the sun in January.", "topk_rank": 16 }, { "id": "corpus-1172132", "score": 0.6761228442192078, "text": "I'm not asking why it's called the solar system. I'm asking if there is an official title for it.\nWhile I'm here do our moon and sun have names?\nFor example one of the moons of Mercury is named phobos.", "topk_rank": 17 }, { "id": "corpus-325258", "score": 0.6754408478736877, "text": "Such events are quite common in the outer solar system where the Sun appears to be smaller. It is possible when Amalthea, Io, Europa, Ganymede and Callisto occults the sun on Jupiter (_URL_1_), Janus, Mimas, Enceladus, Tethys, Rhea, Dione and Titan for Saturn (_URL_0_) and for many other moons on the outer planets.", "topk_rank": 18 }, { "id": "corpus-247347", "score": 0.6749698519706726, "text": "Depends on where you are. The moon would experience a night and day cycle equal to it's orbital period around the moon. If you were on the side of the moon facing the gas giant, you would also have very bright nights whenever they are illuminated by the gas giant. The phase of the gas giant, and how it lights the moon throughout the night, would vary throughout the year. If you were on the far side of the moon from the planet, you would have very dark nights like we have here on Earth away from cities. Judging by the number of moons around our gas giants, there would likely be other moons in the night sky that would provide modest illumination, and go through a very complicated series of phases and times of appearance.", "topk_rank": 19 } ]

[ { "id": "corpus-325368", "score": 0.7338277697563171, "text": "It's called a Hypnic jerk. The exact cause is unknown. The consensus among researchers is that as you drift off and your muscles relax your brain misinterprets this as falling. Your brain then sends signals to arm and leg muscles to regain balance. This would also explain the falling sensation some people experience just as they drift off. Hypnic jerks fall under the broad category of Myoclonic jerks." } ]

[ { "id": "corpus-52579", "score": 0.6968793869018555, "text": "Your body becomes paralyzed during REM sleep because certain neurotransmitters (GABA and glycine) are released in your brain to inhibit your motor cortex. The area that controls oculomotor (eye) movements is in a nearby and connected but separate area. So your brain inhibits the primary motor cortex but not the area that does oculomotor movements.", "topk_rank": 0 }, { "id": "corpus-257639", "score": 0.6965768933296204, "text": "> Muscle tone is usually reduced during non-REM sleep (hypotonia) and is sometimes nearly absent during REM sleep (atonia). This reduction in muscle tone, as well as changes in activity in the cortex and other motor generators is usually enough to prevent major movements like rolling out of bed. see: _URL_0_", "topk_rank": 1 }, { "id": "corpus-119596", "score": 0.6955590844154358, "text": "If you're talking about [hypnic jerks](_URL_0_), it has been suggested that it is an old reflex that prevented our tree-dwelling ancestors from falling off their lofts while falling asleep. > A study at the University of Colorado has suggested that a hypnic jerk could be \"an archaic reflex to the brain's misinterpretation of muscle relaxation with the onset of sleep as a signal that a sleeping primate is falling out of a tree. The reflex may also have had selective value by having the sleeper readjust or review his or her sleeping position in a nest or on a branch in order to assure that a fall did not occur.\" Source: _URL_0_", "topk_rank": 2 }, { "id": "corpus-325117", "score": 0.695263147354126, "text": "It is called a [Myoclonic](_URL_0_) Jerk. It happens because your brain misinterprets your muscles going limp as you falling.", "topk_rank": 3 }, { "id": "corpus-2234400", "score": 0.695148229598999, "text": "Hi All,\n\nI only have minor twitches while I am awake, however when I am asleep my entire body spasms quite violently. I also often wake up with a crawling / aching feeling on the soles of my feet, calves and ankles - and then cannot get back to sleep for the pain. \n \nUsing a hot water bottle dulls the sensation enough to get back to sleep, but the weather is so damn hot its not feasible until the weather cools down. \n\nDoes anyone have any tips please?", "topk_rank": 4 }, { "id": "corpus-142303", "score": 0.6949194073677063, "text": "I'm not 100% sure of this, I read it a few years ago and don't remember the source. You are meant to fall asleep gradually, however when super tired you can fall asleep too quickly, your muscles relax and your brain thinks you are falling. The jolt is an automatic, brace for impact, sub reflex.", "topk_rank": 5 }, { "id": "corpus-2542691", "score": 0.6946265697479248, "text": "Hi group! \n\nI am a 26 y.o. Male and I’m trying to figure out why I’m experiencing symptoms similar to nocturnal seizures or sleep apnea (while I wait to get into a doctor.) \n\nI have been dealing with years of headaches and mental malaise and poor sleep. I’ve had MRIs come back negative for oddities and doctors never really know why I’ve been suffering for years. I have a history of concussions, so they often just place the weight on brain trauma. \n\nWell, I decided to start recording my sleep and boy was I surprised what I heard!! \n\nNearly every night I am waking up and either sitting up and staring into the abyss for several minutes or bolt up and while sleeping, literally spit several times like spitting a loogey. It’s always disturbing to hear! I’d include a recording if I could figure out how to! This happens almost every night. \n\nI wake up depleted with a foggy head, dizzyness, anxiety, dissociation, and just a general icky ness. \n\nWhat were your symptoms and how did you pin point that you were seizing? Can seizures be non-traditional in nature? Meaning, there is no uncontrollable body flailing, etc?", "topk_rank": 6 }, { "id": "corpus-58687", "score": 0.6945381760597229, "text": "This is called Sleep Paralysis. It occurs during REM(Rapid-Eye-Movement) sessions in your sleep in which your brain is deleting useless information such as the clothes you wore 3 weeks ago. It occurs for this specific reason, to not move and possibly injure yourself in your sleep. Obviously some people have defects in which they sleepwalk. And on the flip side some people can actually go into sleep paralysis while awake, not during REM.", "topk_rank": 7 }, { "id": "corpus-922089", "score": 0.694059431552887, "text": "So this is the first time I have ever seen this. It's like he's just about to fall deep asleep and his body shakes and he moves to stop it. It's been like 30 mins now at the time of this writing. I'm freaking out.\n\nI Googled and only seen things on narcolepsy and seizures. I have no idea. Anyone else experience this?", "topk_rank": 8 }, { "id": "corpus-125064", "score": 0.6940425634384155, "text": "It's called a [hypnic jerk](_URL_0_) and apparently happens to lots of people. I like the possible explanation that the primate part of your brain thinks you're about to fall out of your tree.", "topk_rank": 9 }, { "id": "corpus-72871", "score": 0.6939921379089355, "text": "It's called a hypnic jerk. Basically your brain is testing to see if your body is dying.", "topk_rank": 10 }, { "id": "corpus-63284", "score": 0.6932744979858398, "text": "In the split second before your brain goes fully asleep, your muscles relax all at once (atonia?). If your brain catches this before it totally zonks out, it'll register the sensation as falling or losing your balance, and will reflexively try to regain balance.", "topk_rank": 11 }, { "id": "corpus-2545195", "score": 0.6931203007698059, "text": "Is it just me or you guys also sometimes experience a kind of a jerk when trying to sleep at night?It happens to me when I eat heavy or spicy dinner ora meat like a goat meat (but not a chicken meat). And also i get startled several times a day...I have done ECG,Echo, Thyroid and everything are normal.", "topk_rank": 12 }, { "id": "corpus-102367", "score": 0.6931183934211731, "text": "From what I understand, as you fall asleep, your heart rate drops. If it drops too quickly, your brain sends a jolt to make sure you're still alive. Because it cares about you and whatnot, the nag.", "topk_rank": 13 }, { "id": "corpus-127192", "score": 0.6929076313972473, "text": "Another reason can be bruxism. The nightly grinding of the teeth can cause the the neck muscles to tense up. If it is strong enough it is visible on worn down teeth. Bruxism can be caused by e.g. stress or also by other rem sleep disorders.", "topk_rank": 14 }, { "id": "corpus-90916", "score": 0.6927064657211304, "text": "The body (guided by neurons called REM sleep-on cells) are told to stop reacting to certain brain chemicals, which means that you are safe during your sleep cycle. For people where this stoppage is interrupted have symptoms like sleep walking and perceived sleep paralysis. from [here] (_URL_0_) > The release of certain neurotransmitters, the monoamines (norepinephrine, serotonin and histamine), is completely shut down during REM. This causes REM atonia, an almost complete paralysis of the body, due to motor neuron inhibition.", "topk_rank": 15 }, { "id": "corpus-1758405", "score": 0.6927000284194946, "text": "On days I'm unusually anxious or stressed combined with going to bed late I might get these weird episodes where as soon as I close my eyes I get this short surge of euphoria shoot through my body and it usually makes me panic and my body starts shaking, yet I can't seem to move myself. One time it was so bad I fell off the bed and layed shaking on the ground. I've been to the doctor, neurologist and somnologist and none of them know what it is. Just wondering if anyone has experienced this before", "topk_rank": 16 }, { "id": "corpus-81417", "score": 0.6923072934150696, "text": "Your body \"turns off\" your skeletal muscles during sleep so you don't thrash around. They should come back under your control as you wake up, but some people can get the order out of sync and awake before they can move (the other way around you move while asleep). It is so scary because your brain will try to come up with a reason you can't move, and this often takes the form of some type of restraint such as a gremlin sitting on your chest. Being immobile is a big threat to your survival so it tends to cause panic.", "topk_rank": 17 }, { "id": "corpus-2234934", "score": 0.691234827041626, "text": "First off, if this continues for another week or so, yes, I am going to see a doctor. I kinda just want to hear it's happened to someone else. \n\nI've been fitness-y for about 8 years now, doing random running, weights, bodyweight stuff. Since July, I've really gotten serious with lifting heavy, and have been doing SL pretty religiously. I've also amped up the intensity at my sport. Within the last month or so, I've hit a point where the weights I'm lifting have moved from \"this is challenging\" to \"holy shit this is heavy!\" I'm happy with my developing strength and physique.\n\nMy one problem is that I have started having insane twitching and muscle spasms at night. As soon as I drift out of consciousness, according to my husband, it's like a dance party. I've always jerked a little bit as I'm falling asleep, but it's gotten crazy, to the point that it's keeping my husband awake. I get it in the morning, too, and often wake up feeling like I'm vibrating and I've got electricity running through me. \n\nThe only reason I connect it with exercise is that in the past, after a really hard leg workout, I've had like one night of the crazy legs. And, it seems like this time, the only thing that's changed in my lifestyle is that I'm working out harder. \n\nBTW - I'm almost certain it's not RLS. I don't feel like I need to move my legs - they (and my arms and fingers and abs) just move on their own. \n\nDoes anyone else get this?", "topk_rank": 18 }, { "id": "corpus-189631", "score": 0.6912268996238708, "text": "This is called clonus or myoclonus, and is unrelated to your heart-beat, other than that it may occur with a similar frequency (that is, beats/twitches per second/minute). It isn't really known what causes these involuntary twitches in normal people. There are some rare diseases like Motor Neuron Disease/ALS which can first appear as these twitch-like movements (though typically these would be more chaotic, rapid 'fasciculations'). It may be a spontaneous phenomenon of electrical systems, like ectopic heart beats, since nerves are 'electrical', or at least based on flow of charge. It may be that there has been an 'injury' to that nerve, such as knocking it or even sitting/resting on it unusually. It may be that some of the salts the body uses to conduct the aforementioned charge are low/high in supply and lead to accidental signal firing. In short, we have a good idea of the 'what', but a pretty poor understanding of 'why'.", "topk_rank": 19 } ]

[ { "id": "corpus-325369", "score": 0.781805694103241, "text": "The eight remaining planets (sorry pluto) orbit in *approximately* the same plane. The reason being that they formed from the [Protoplanetary disc](_URL_0_) that formed around the young sun billions of years ago. In general, clouds of gas collapsing under gravity tend to form discs, because of conservation of momentum/angular momentum. Pluto was always the odd man out, being offset from the earth's orbit by about 17 degrees, and this was actually a contributing factor in its reclassification." } ]

[ { "id": "corpus-96419", "score": 0.7421454787254333, "text": "There's not that much information about other solar systems, but generally there doesn't seem to be a reason to assume they orbit in the same way as the entire galaxy, as the local \"turbulence\" and random variation of gas clouds would have greater effect than the overall direction of the galaxy spinning. The solar systems aren't necessarily even oriented on the same level as the galactic plane. For example the plane of our solar system isn't on the same plane as the galactic plane, but more [like this](_URL_0_).", "topk_rank": 0 }, { "id": "corpus-129644", "score": 0.7416141629219055, "text": "Because they're mostly all on one horizontal plane in reality. [It's definitely not perfect](_URL_1_), but it's pretty damn close. [Here's literally the first video I found explaining why planets form in one plane](_URL_0_). I find a video helps because, at least for me, it's much easier to understand with a visualization (EDIT: And after watching it, it's not a bad video at all!). But basically, when you have a cloud of materials, as they clump together to begin forming the sun and protoplanets, they'll start to rotate, and as they collide and spin the dust and clumps will cancel the \"up and down\" movement relative to the plane [of the ecliptic] and leave a more or less pretty thin plane of planets and other junk.", "topk_rank": 1 }, { "id": "corpus-323088", "score": 0.740477442741394, "text": "For bound two body orbits, like you mentioned, the orbits are generally an ellipse, but circles are a special type of ellipse, which you can have for a specific orbital energy and angular momentum in the system. In theory, nothing forbids circular orbits, and it's often a useful assumption when doing simple calculations. For example, most of the planets in the solar system have very nearly circular orbits, with eccentricities around 0.01. In practice, orbits get screwed with by the gravitational pull of all the other bodies in the solar system, so even an ellipse isn't a perfect description. As the solar system evolves, the eccentricities of the orbits change slightly due to the gravitational effects of other planets, and the perihelion of the orbit precesses.", "topk_rank": 2 }, { "id": "corpus-323059", "score": 0.7379820942878723, "text": "Planets follow the disc orbital paths because they form along with the parent star from the same rotating and flattening cloud of gas and dust, so it would be unlikely to find a naturally occurring planet on a different plane, unless the said planet didn't form with the original star (i.e. it's a captured planet, possible a rogue planet that wandered into the existing system). There's nothing, afaik, physically preventing differing orbits besides the origin though, so I could buy a sci fi scenario where a sufficiently advanced race purposefully creates a Rutherford atomic model style solar system by manipulating planetary positions.", "topk_rank": 3 }, { "id": "corpus-54577", "score": 0.7370262742042542, "text": "Its tilted relative to the orbital plane. Most planets rotate somewhat perpendicular to their plane on orbit around the sun. Uranus on the other hand is weird and its poles basically face the sun.", "topk_rank": 4 }, { "id": "corpus-164985", "score": 0.7369897365570068, "text": "Interestingly, almost all the planets in the solar system orbit the sun and rotate around their axes in the same direction! The exceptions to this are Venus which rotates around its axis in the opposite direction, and Uranus which has its axis tilted almost 90° and so rotates \"top to bottom\" instead of \"left to right\". Dev_our gave a pretty decent simply description of conservation of angular momentum. If you'd like, I could give you a more detailed description of exactly why the planets rotate, including why they (almost) all rotate and orbit in the same direction.", "topk_rank": 5 }, { "id": "corpus-2061697", "score": 0.7368553876876831, "text": "Did some preliminary googling (unsuccessfully), but am wondering if an orbit like this is possible\nWhere \"r1==r2\", and so is \"r3==r4\" - and consequently, you have two identical Apoapsis, and two identical Periapsis.\n\nMost orbits that I've seen in diagrams are either circular or elliptical with a different r1 and r2.\n\nThe context of this question is mainly about a large body, small body (Earth, Moon etc) orbit, but any extra discussion about achieving a similar orbit with spacecraft or binary orbits(?) is cool too.\n\nThanks in advance for any help with this.", "topk_rank": 6 }, { "id": "corpus-289381", "score": 0.7361302375793457, "text": "The sun rotates. So yeah the North and South pole are the points where the rotational axis coincides with the surface. Furthermore the sun has a magnetic field that has a significant dipole component. This dipole is aligned with the rotational axis, so the dipole poles are at the North and Southpole as well. The planets orbit roughly on the solar equatorial plane. The orbits are slightly inclined but only a few degrees. (Pluto has a much stronger inclination with ~17°, another factor that makes it different from the other planets.)", "topk_rank": 7 }, { "id": "corpus-292823", "score": 0.7357865571975708, "text": "This [site](_URL_0_) gives a full explanation to it. Essentially the answer is no, if you use the rigorous definition of alignment. This is because the planets don't rotate at the same angle and plane as each other, making exact alignment almost impossible. Using a more flimsy definition of alignment (where the planets line up if you look at the solar system hypothetically in 2d from top down) the planets are closest to this every ~3400 years or so; but only exactly aligned from 2d perspective every 340 million years.", "topk_rank": 8 }, { "id": "corpus-313105", "score": 0.7353381514549255, "text": "An orbit must have one focus on the centre of the primary body. Also, orbits lie in a plane (orbital plane) and the focus lies on this plane. So this plane must intersect the equatorial plane. In particular, unless the orbit lies exactly on the equator, part of it will be in one hemisphere and part in the other. The points where the orbit crosses the equatorial plane are the nodes (ascending and descending) and the line connecting them is the nodal line, which is also the intersection of orbital and equatorial plane. No escaping this!", "topk_rank": 9 }, { "id": "corpus-324756", "score": 0.7352097034454346, "text": "All of the planets formed from the solar nebula, a single large cloud of gas. The cloud of gas collapsed into a disc, and the planets formed from that disc, which means they all orbit the same way that the original disc did. This should be the same in any planetary system, so planets orbiting in nice circular orbits in the same direction should be the norm. However, weird things do happen. Random close encounters can drastically change the orbit of a planet. A star could capture a rogue planet. So you'd expect a small number of planets to have odd orbits. With smaller objects like asteroids, little interactions have a bigger effect, so these things tend to scatter around a bit more. So even though most of the asteroids are in the disc of the solar system, there are a decent amount that are above or below or in weird orbits. Comets can orbit backwards too.", "topk_rank": 10 }, { "id": "corpus-314222", "score": 0.7342368960380554, "text": "No, the definition of an orbit is not very well defined but \"a regular curved trajectory around a point in space\" is a ok compromise. If the barycenter is more or less equidistant to both object then you can say that they orbit each other.", "topk_rank": 11 }, { "id": "corpus-312557", "score": 0.7341992855072021, "text": "[This question](_URL_0_) in the FAQ probably explains this sufficiently. Although actually the planets are very similar, if you consider them as two separate groups.", "topk_rank": 12 }, { "id": "corpus-165713", "score": 0.7336867451667786, "text": "The solar system is mostly \"flat\", although some planets orbit at slightly different angles. The reason is that the planets in our solar system accreted from the same rotating disk of dust that was on a single plane (more or less). In order to have planets that orbit the sun at a crazy angle, they'd have to be \"foreign\" planets that came from another system at an odd angle and got caught in the sun's gravity well.", "topk_rank": 13 }, { "id": "corpus-324136", "score": 0.7334611415863037, "text": "No. The celestial equator (plane containing Earth's equator, separating the night sky into the Northern and Southern halves), the ecliptic (plane containing the solar system), and the galactic plane (containing the stars of the Milky Way) are all unaligned with each other. The relative angles are 23.4°, 60.2° and 62.9°. [_URL_0_](_URL_0_) Btw, there is only one \"solar system\", i.e., the system around \"Sol\", the other name for the Sun. Systems around other stars are called stellar systems.", "topk_rank": 14 }, { "id": "corpus-92091", "score": 0.7332547903060913, "text": "Planetary systems are believed to come about from big balls of dust/gas collapsing. The center forms the star, then rest forms the planet. If the original dust/gas ball has any spin at all, that angular momentum must be conserved as everything collapses, causing the whole mess to form a disk-shape before we managed to get any planets. Once you're in the disk shape everything is basically almost in one plane, so planets that form from there will all have very similar orbital planes unless something wierd happens.", "topk_rank": 15 }, { "id": "corpus-313067", "score": 0.7316597700119019, "text": "There's no reason it would be on the same plane as the Milky Way. The nebula the solar system formed in would have had matter going in all different directions unrelated to the direction the galaxy as a whole is spinning.", "topk_rank": 16 }, { "id": "corpus-325027", "score": 0.7313629984855652, "text": "What iorgfeflkd is talking about is called \"precession\", all planets have it to some extent, and it is exactly what you're talking about.", "topk_rank": 17 }, { "id": "corpus-325442", "score": 0.731146514415741, "text": "All planets' gravity affects all other planets. But it's possible for multiple planets to be in stable orbits within a single star's habitable zone, yes.", "topk_rank": 18 }, { "id": "corpus-5589", "score": 0.7306807637214661, "text": "A nebula ie a cloud of gas starts to collapse. The conservation of angular momentum result in that is spins. If you have a spinning cloud with particles that travel in random direction they start to collide. A spinning direction will be dominant and a disc start to form Particles that have a another orbit then the disc will pass trough it and collide with it. so the only way to orbit and not collide is to be in the disc. Planets are formed in the disk so they will all be in the same plane.", "topk_rank": 19 } ]

[ { "id": "corpus-325370", "score": 0.6524102687835693, "text": "erm, because carbohydrates have calories. Not sure how you make the cake without flour." } ]

[ { "id": "corpus-2010868", "score": 0.6197652816772461, "text": "Yesterday, I had craving for some sweets, so I tried to make some fatbomb with some 100% cocoa. And instead of sugar, I've read about sugar alternatives. And more I read on this subreddit, more confused I got. Someone said use stevia, a other person said use ONLY liquid stevia. Someone said not to use stevia and use another sugar alternative.\n\nCan someone explain very simply or rather just suggest a sugar alternative that you use that's keto friendly?", "topk_rank": 0 }, { "id": "corpus-137448", "score": 0.61976158618927, "text": "Different beverages have different ability to build and \"conserve\" foams. This has to do with proteins and other stuff. They build chains that stabilize CO2 bubbles in a way that they build foam. Much like tiny soap bubbles that are all interconnected. I think in Apples its the pectin that stabilizes the foam.", "topk_rank": 1 }, { "id": "corpus-1855954", "score": 0.6196783185005188, "text": "So, first question, what the heck does SV/NSV mean? I'm seeing these acronym's all over the damn place and I simple can't figure it out. \n\nSecondly, I'm going out with some work friends this week. I've kept myself below my calorie goal for over a week, and will be again this week, and I'd hate to break that streak. However, I want to be able to cut loose and drink without worrying about counting too much. What drinks are best for drinking and keeping calories low?", "topk_rank": 2 }, { "id": "corpus-174947", "score": 0.6196368932723999, "text": "A lot of sports drinks taste kinda salty. (I'm sure the word electrolytes is relevant here, but I won't pretend to understand). Besides, a salty [lassi](_URL_0_) is delicious! So I guess the answer is subjective taste and culture?", "topk_rank": 3 }, { "id": "corpus-1477958", "score": 0.6196300387382507, "text": "I've recently discovered Mio water flavoring, and it's helping me so much. I have to be honest, I hate the taste of plain water when I'm not thirsty, and I very rarely feel thirsty.\n\nI've gotten more than enough daily water though through using 0 calorie, sodium free water flavoring. (it has sucralose in it and not aspartame)\n\nIs my body benefitting from this just as much as it would if it weren't flavored, or should I try to limit it more? I still drink plain water, I just don't love the taste of it.", "topk_rank": 4 }, { "id": "corpus-2763290", "score": 0.6194681525230408, "text": "A lot of the recipes I want to use have things like \"1 cup of sugar\" or \"1 cup of substitue\". I use EZ-sweetz, and only require a few drops to achieve the sweetness level I desire. What can I use as the extra \"filler\" for missing 1 cup of volume?", "topk_rank": 5 }, { "id": "corpus-9112", "score": 0.6194635033607483, "text": "It's likely that the coke in glass is \"mexican coke\" or similarly foreign. Different cokes in different countries have different recipes, so its entirely possible that the coke you had in the glass bottle had real sugar cane while the coke in the plastic had fructose corn syrup", "topk_rank": 6 }, { "id": "corpus-76057", "score": 0.6193856596946716, "text": "Cold liquid can hold gas better than hot liquid. When soda is heated, the gas escapes and hence the ka boom", "topk_rank": 7 }, { "id": "corpus-67678", "score": 0.6193795800209045, "text": "Because they provide a lot of vitamins and minerals (and some proteins) and are tasty. We can get plenty of calories. In fact, it is *too* easy nowadays to get enough calories. Why should lack of calories be a downside?", "topk_rank": 8 }, { "id": "corpus-76449", "score": 0.619351863861084, "text": "Glass bottles also work in my experience. The reason is that the plastic used in the normal bottles, PET, isn't really airtight on a molecular level. So a very little amount of oxygen is able to reach the drink, altering the taste slightly but noticeably. This 'issue' with PET is also the reason while drinks in plastic bottles usually have a best before date set just a couple of months into the future while in cans and glass bottles it's often set more than a year into the future.", "topk_rank": 9 }, { "id": "corpus-2763674", "score": 0.6193480491638184, "text": "Maybe this is just an Australian thing, but even if I buy in bulk (so healthy) I expect to pay $4-5/L for any brand of energy drink, compared to $1-2/L for regular soft drink. What gives? Are all those fantasy ingredients legitimately expensive to source?", "topk_rank": 10 }, { "id": "corpus-21989", "score": 0.6192892789840698, "text": "Calories are the amount of energy your body can extract from an item of food. Water does not provide energy.", "topk_rank": 11 }, { "id": "corpus-237884", "score": 0.6192397475242615, "text": "we do have these crackers/biscuits that are used already. they come in packs of 2 and have 2300 calories. _URL_0_", "topk_rank": 12 }, { "id": "corpus-293272", "score": 0.6192389130592346, "text": "It's like taking a vitamin supplement. If you're deficient, yes there will be a benefit. If you're not deficient, it's unlikely to give you any extra benefit, but then again it won't hurt. This is why it's sometimes recommended to take a multivitamin daily in addition to eating a healthy diet, just to be on the safe side. Okay, I just took a look at the nutritional info of vitaminwater (the branded product), and I'm not impressed. The quantities of vitamins/minerals are nothing to be excited about, and the bottle has 32 grams of sugar! While it's marginally healthier than a bottle of Coke, why anyone would want to ingest 32 g of sugar just to get a small amount of vitamins is beyond me.", "topk_rank": 13 }, { "id": "corpus-2694964", "score": 0.6192274689674377, "text": "Saw a couple of 'zoats' posted. I decided to research it and though i found a lot of recipes via pinterest, they were not exactly low cal. Im sticking to 1290cals a day and I can't exactly use massive amounts of maple syrup or nut butters as these recipes suggested. \n\nCan anyone steer me in the direction of a tasty, low cal option? Or suggest substitutions for some ingredients?", "topk_rank": 14 }, { "id": "corpus-321048", "score": 0.6191921830177307, "text": "Non-carbonated beverages may also have dissolved gases in them, albeit not as much as carbonated ones. The walls of the glass usually have impurities such as dust or even scratches on them that act as nucleation sites for the dissolved gases to grow on as bubbles.", "topk_rank": 15 }, { "id": "corpus-483189", "score": 0.6191368103027344, "text": "Despite their demonization... Anyone else feel like soda and other sweet beverages help suppress appetite? They make it so I don’t have to eat a full meal, often can even skip the meal", "topk_rank": 16 }, { "id": "corpus-37230", "score": 0.6190620064735413, "text": "Part one: Brand loyalty, cultivated over decades. There are lots of ['house brands' of cola](_URL_0_), many of which do taste very close to either Coke or Pepsi, but people are willing to pay more for the brand name because they are assured that it will taste the same as every other Coke or Pepsi they've had in their lifetime. Part two: distribution. Coke and Pepsi can maintain that brand loyalty because you can't go anywhere that sells soda without one of those two being available. Fast-food restaurants are essentially forced to pick one or the other, lest they run the risk of turning off their customers. Ones that aren't, like local mom-and-pop restaurants, often carry *both* for this reason. Every grocery store, convenience store, WalMart and mom and pop, vending machine, has one of those two brands. So, since customers can nearly *always* buy a Coke or Pepsi, rather than experimenting with other brands, it's very difficult for any new brand to gain a toehold in the surgary brown water market.", "topk_rank": 17 }, { "id": "corpus-1479615", "score": 0.6190295219421387, "text": "I've been on a cut for about 5 weeks and things are progressing great. My only \"cheat\" thing is I completely down diet sodas/carbonated beverages on the weekends. It's my one solace when I'm at dinner with my friends or out and about and can't drink or eat. I've had lots of people jokingly say that I may be losing weight but am still messing up muscle growth and such due to me drinking so many of these on the weekend (rough guesstimate I'll probably have 20 cans of diet whatever between Friday and Sunday). So what's the research behind this? The only thing I see in the nutrition that's slightly bothersome is the sodium levels but hell I douse my chicken in hot sauce so I just kinda ignore it. Thoughts? Know research articles on this? Would really like to know what the science behind these claims are", "topk_rank": 18 }, { "id": "corpus-190468", "score": 0.6190163493156433, "text": "The foam on beer is stable because of the proteins in it, so the bubbles break less easily and a head can form. Fizzy drinks like soda contain much less protein so the bubbles formed are less stable, pop more easily, and are therefore much harder to foam.", "topk_rank": 19 } ]

[ { "id": "corpus-325371", "score": 0.7530437707901001, "text": "This doesn't work, but it's interesting to examine why it appears to work for a few cases more closely. x^2 - 1 = (x + 1)(x - 1) If x is prime, and x does not equal 2, then (x + 1) and (x - 1) are both even numbers. Let (x - 1) = 2k, then the test is that if k(k+1)/6 is a whole number, then x=2k+1 is prime. Obviously, either k or k+1 is an even number, but k cannot be odd, as then 2k+1 would be an even number and therefore not prime. Then k is an even number, and k+1 is odd. Let k=2j. Then the test becomes: if j(2j+1)/3 is a whole number, then 4j +1 is prime. Obviously, exactly one of (x-1)=4j, x=4j+1, (x+1)=4j+2 is divisible by 3, and (x-1) and (x+1) are both even. So what the test actually shows is that if (x^2 - 1)/24 is a whole number, then x is not divisible by 2 or 3. I doubt that it is coincidental that this tests the first two primes, so I assume that somewhere along the line someone misunderstood a method of methodically checking divisibility by 2,3,5,7,11,... to see if a number was prime." } ]

[ { "id": "corpus-321633", "score": 0.7153392434120178, "text": "1. According to [this page](_URL_3_), we have calculated (but not stored) all the primes up to 10^(18). Following it's link, we've gotten to 4\\*10^(18). 2. The largest known prime is 22338618 digits long. The largest consecutive prime is 19 digits long. So the largest known prime has 22338599 more digits. Does that help? 3. We're missing almost all of them. The number of primes we're missing has about 22338610 digits. The number of primes we have has 17 digits. 4. My rice is done and I don't have time to check. And I'm too lazy to anyway.", "topk_rank": 0 }, { "id": "corpus-236775", "score": 0.7152806520462036, "text": "I don't know about the Fibonacci sequence, but [let me know if anything here jumps out at you.](_URL_0_) There's nothing uniquely 'decimal' about the Fibonacci sequence, it's just a recurrence relation. But the prime factors of the base will determine a lot of neat tricks for factoring numbers and other number theoretic things. For example, in base 10, if the last digit is a 2, 4, 6, 8, or 0 then the number is divisble by 2. In base 2, a number is even if the last digit is 0, and is odd if the last digit is 1. These may seem obvious, but another example in base 10 is this trick: sum the individual digits of a number, if that sum is divisible by 3 then the original number is divisible by 3. These neat tricks show up in every base, and are a consequence of the prime factoring of that base. I just don't know many off the top of my head for any other than base 10... perhaps a proper mathematician would give you a better answer.", "topk_rank": 1 }, { "id": "corpus-78451", "score": 0.7151158452033997, "text": "In this context, \"find\" means identify numbers that were previously not known to be prime. To give you an idea, the largest known prime has twelve million digits. Dealing with such big numbers is not a trivial task. Only a few new prime numbers are found every year. I don't know why such huge prime numbers are so coveted but I know big prime numbers are used in public key cryptography. Basically it relies on the fact that, in the equation A*B = C, where A and B are coprimes, it's easier to calculate C when you have A and B than to calculate A and B when you have C.", "topk_rank": 2 }, { "id": "corpus-272277", "score": 0.7149398326873779, "text": "How about the [Twin Prime Conjecture](_URL_1_)? If your students can understand what a prime number is (a positive integer that only has two divisors - itself and 1), then the conjecture itself is pretty easy to conceptualize: A twin prime is a prime number that is two more or two less than another prime. (So, 5 and 7 are twin primes. 11 and 13 are twin primes. 29 and 31 are twin primes.) The conjecture assumes that there are infinitely many twin prime pairs. We currently have no proof to demonstrate that this is true. & #x200B; & #x200B;", "topk_rank": 3 }, { "id": "corpus-76373", "score": 0.7149258255958557, "text": "Mathematically speaking, you can define all other numbers purely by multiplying prime numbers. So we don't actually need any non-prime numbers, as we could simply define 4 for example as 2x2. Or 99 as 3x3x11. Obviously this would make daily life a lot harder, hence the other numbers having their own names and symbols.", "topk_rank": 4 }, { "id": "corpus-322586", "score": 0.7148914337158203, "text": "The Great Internet Mersenne Prime Search is looking for ever larger [Mersenne Primes](_URL_3_). These prime numbers conform to the function M_p = 2^p - 1. Their project has created a program, Prime95, that uses factorization and the [Lucas-Lehmer primality test](_URL_5_) to detect prime mersenne numbers, according to the readme. Prime95 also connects with a central server to coordinate the testing of the number space. There exist other methods of finding primes, as well. The [Sieve of Eratosthenes](_URL_4_) is one such method. In general, though, one can detect whether *n* is prime by testing all possible factors between 0 and sqrt(*n*)", "topk_rank": 5 }, { "id": "corpus-54895", "score": 0.7134436964988708, "text": "There's a very simple proof: lets suppose there *is* a largest prime number, we'll call it P. Next we look at the number N = P!+1 (the ! means [factorial](_URL_0_), which means to multiply every number from 1 to P). It's easily provable that N isn't divisible by any number between 2 and P. So now there are two options: either N is prime, which makes it a prime number larger than P, or N isn't prime, which means there is some prime number that divides it - but since no number between 2 and P divides N, this means that this new prime must also be larger than P. Either way we've found a prime number larger than P, which means P cannot be the largest prime number.", "topk_rank": 6 }, { "id": "corpus-319285", "score": 0.7134164571762085, "text": "I did a paper on this so here goes. There exist algorithms that can check if a number is prime or not. These algorithms are probabilistic which means that if the number passes the test there is a certain chance that it is or isn't prime. The most commonly used test is the rabin Miller test. If a number passes it the chance of it not being a prime is 25%. The thing about this test is that you can repeat the test but use different initial seeds each time and thus the probability of it being prime decreases dramatically. The \"seed\" is known as a base. So in rsa a big number is created, we run the test a bunch of times and if it is prime everything's good otherwise we create a new number and repeat. If you want more details about the actual test and an explanation just comment.", "topk_rank": 7 }, { "id": "corpus-155636", "score": 0.7129054665565491, "text": "It means they have proved that a particular number has some property. For example, it's no secret that the following number exists... 6353526374303929879127012501290127402919200192601923419028340912401927492180129801297012912012912261202912061 We don't need to go hunting for it. It's right there. However, is it prime? Is it a square? Is it a solution to < some famous equation > ? Some of these questions are hard or time consuming to answer. If I were to crunch a bunch of numbers and discover that the number above is prime, I could say that I \"found\" a prime number.", "topk_rank": 8 }, { "id": "corpus-2060569", "score": 0.7128755450248718, "text": "When I have problem like (5)/(6)+(1)/(4) and I try to find the LCD by prime factorization, so 6's are 2, 3 and 4's are 2 and 2, why is it that it becomes 2 \\* 2 \\* 3 and not 2 \\* 2 \\* 2 \\* 3 since we have three 2's there. I understand that 12 is the answer and the lcd but I dont understand quite well why we only end up picking two 2's instead of three 2's.", "topk_rank": 9 }, { "id": "corpus-821340", "score": 0.711485743522644, "text": "I've tried to do a little research, but I'm not really able to to word my question to get the proper results.\n\nGiven a number and one of its factors, I want to know how to mathematically determine (without nesting or recursion) how many times that particular factor is present in the factorization.\n\nIt's probably best to look at prime factorization as an example. I'm looking at determining the power of one of the prime factors, given which factor I want the exponent of.\n\n72 factors into 2^3 X 3^2. Given 72 and 2, I want a function that returns 3. Given 72 and 3, I want a function that returns 2. Does anyone know something that could help me? I'm not looking for a script or an answer to a particular number, I want a rule or formula that I can apply to all numbers (positive integers at least).\n\nThanks in advance", "topk_rank": 10 }, { "id": "corpus-321704", "score": 0.7113920450210571, "text": "> It's a common thing to look up phone numbers in pi, and it's a common saying that every Shakespeare ever written is encoded in pi somewhere, I just want to note this this is commonly believed, but as yet unproven. A infinite decimal in which every possible digit sequence appears *somewhere* is called a [\"normal number\"](_URL_1_). It has [not been proven that pi is a normal number](_URL_0_). It's expected to be, but no one has shown a mathematical proof that pi does contain every possible sequence of digits.", "topk_rank": 11 }, { "id": "corpus-924022", "score": 0.7112812399864197, "text": "Hi everyone\nI've made an algorithm that aims to tell if a number (a) is a prime number.\n\nIt is working but it also prints \"None\" after the desired answer.\n \nFor example when the input is 59 the output is :\nTrue\nNone\n\nHow can I take off the None ?\n\nHere is my code :\n\n", "topk_rank": 12 }, { "id": "corpus-323231", "score": 0.7109231948852539, "text": "It would make prime factorization trivial, multiplication easier, and addition extremely difficult. You'd basically have to work out the numbers in a more useful format, add them, and then factor that. But that last step would get really difficult with large numbers. Also, as others have noted one is not prime. If you have a space for one, you could stick any number there and it wouldn't matter.", "topk_rank": 13 }, { "id": "corpus-165872", "score": 0.71087646484375, "text": "People are gonna bring up RSA encription and that's fine, but that's not really what the guy was talking about. He was approaching the question as a guy who apparently is really into number theory—it's not an objective fact that prime numbers are more \"important\" than any other class of number. They are very fundamental objects in the theory of integers though. The fundamental theorem of arithmetic (this is what he was referring to) states that every number can be factored into a *unique* product of prime numbers. So, for instance, 18 = 2 x 3 x 3 = 2 x 3^2 or 24 = 2 x 2 x 2 x 3 = 2^3 x 3 or 35 = 5 x 7. This \"prime factorization\" is sort of like each number's fingerprint. The prime factorization of a number uniquely identifies that number, and it tells us all kinds of other things about the number too.", "topk_rank": 14 }, { "id": "corpus-1129432", "score": 0.710425853729248, "text": "Currently reading a book called Mathematical Mysteries by Clawson, which I recommend if you're interest in math theories. I enjoy the theories, but a lot of the book covers what seems to be pointless pursuits, like discovering the largest prime numbers, without actually explaining any deeper reason for doing so. I get the sense that a lot of mathematics isn't as much about the \"why\" as it is the \"how.\" Anyone who deals with math care to explain why math is so interesting?", "topk_rank": 15 }, { "id": "corpus-25256", "score": 0.7103487253189087, "text": "tl;dr: there can't be a finite number of prime numbers because, if you ever had _all_ the primes, you could easily construct a number which isn't divisible by any of them, which means you don't have all the primes, which contradicts our assumption.", "topk_rank": 16 }, { "id": "corpus-184161", "score": 0.7100789546966553, "text": "When doing encryption, two things has to be true: 1) It must be easy to calculate 2) It must be hard to reverse Multiplying two prime numbers is insanely easy for a computer, so 1) is true. Finding out which two prime numbers were multiplied together to get a number is impossibly hard to do (within a reasonable time frame) for a computer. Basically, the only way to truly know which two primes multiply together to form 144 483 604 528 043 653 279 487 is to multiply every single prime with every single other prime to see if it gives the correct answer, and each calculation takes some time. At some point you'll get the answer, sure, but what does that help if your calculation takes fifty thousand years?", "topk_rank": 17 }, { "id": "corpus-264354", "score": 0.7099061608314514, "text": "Being large prime numbers, their cycles tend not to coincide with predatory cycles -- especially not successively. One of the few examples of prime numbers emerging in nature that I've been able to find. (Other than from intelligent life.)", "topk_rank": 18 }, { "id": "corpus-2059918", "score": 0.7097306251525879, "text": "Have you ever sat down, made an exam, thought \"I don't remember this formula... Ah well, let's just work with what I've got!\" and aced it. Or discovered a pattern in a series of numbers and were able to formulate it. Those always amuse me, since most of the time the teachers give interesting responses. Here's such a story from me, although I don't remember the exact formula anymore:\n\nDuring high school math (I was around 15 at the time), we had a test on finding minima and maxima in functions. However, I couldn't remember the formula at all. So, I started working on the problem, and actually found an answer I was confident in. Since it's so long ago, I don't know my approach anymore, sadly. However, when we got our test results back, I got called to the front by the teacher. He asked me how I used the wrong formula, and came up with the right answer. I explained the situation to him, and he laughed.\n\nAfter class, together we tried the formula on other problems, but it didn't give another right answer. I got all the points for the question, and had a pretty fun afternoon with my teacher. Too bad I didn't discover a new formula.", "topk_rank": 19 } ]

[ { "id": "corpus-325372", "score": 0.811069905757904, "text": "There are a number of genes that have been found to be associated with increased risk of developing Alzheimer's disease. The first one discovered was the ApoE4 allele, which increases risk by between 10 and 30 times. Others have recently been discovered which increase risk by smaller magnitudes, such as presenilin-1 and -2 and amyloid precursor protein (APP). Mostly these are associated with early-onset or familial forms of Alzheimers. Apart from the very rare familial form, it's not hereditary in the classical sense of the word - one of your parents having AD does not mean that you're going to get it. Quite frankly, we still don't know what causes it. It's therefore not entirely possible to determine whether or not it's genetic." } ]

[ { "id": "corpus-51148", "score": 0.7677776217460632, "text": "Alzheimer's is a tricky thing. Although it comprises a hefty chunk of modern day research, our attempts at narrowing its underlying causes is progressing but is in no way resolute at this time. However, it seems there are some clear genetic predispositions. Japan may ultimately comprise of a population of human beings lucky enough not to carry a high number of mutations that potentially lead to the development of Alzheimer's. Another reasoning could be diet and health.", "topk_rank": 0 }, { "id": "corpus-96100", "score": 0.7504971623420715, "text": "A hereditary disease is purely genetic. If I have a mutation in a gene so that I can't express a particular enzyme, it is a hereditary disease - the gene was passed down from my parents. When they say a disease is not hereditary, it means the gene alone isn't what's responsible. However, as with basically everything else, genes can make someone predisposed for a particular disease.", "topk_rank": 1 }, { "id": "corpus-1255801", "score": 0.7340654730796814, "text": "My mom has been having difficulties for over a year now and we finally got her to go to the doctor. I’m guessing it’s early onset Alzheimer’s, she is only 53. Doctor is going through the steps as to be expected. \n\nIn the mean time I am going to have some genetic testing done to see if anything noteworthy comes up. Has anyone else done genetic testing? How did it go?", "topk_rank": 2 }, { "id": "corpus-1256055", "score": 0.7339839935302734, "text": "I've heard that adhd is genetic and often passed down through families, but so far I'm the only one diagnosed. I've been analyzing family members to see if if anyone else expresses symptoms and though there is definitely neuro diversity through my family, I'm the only one who seems to match the symptoms. I'm pretty textbook inattentive add, but it's making me question my diagnosis. Are there instances when it's not genetic, and if so, how would it be explained?", "topk_rank": 3 }, { "id": "corpus-2596918", "score": 0.7302941083908081, "text": "It’s interesting. This has been on my mind for a while. How can natural selection act on a gene that hasn’t yet been expressed? My thought is that maybe people who carry the gene for Alzheimer’s and haven’t yet developed it are less likely to reproduce because either they think it’s their social responsibility to not pass on the gene to their own offspring, or because their own parents currently have Alzheimer’s and are therefore so busy with elderly parental care that they don’t have enough time/energy/drive to be boning down", "topk_rank": 4 }, { "id": "corpus-2596579", "score": 0.7298447489738464, "text": "this is in conjunction with an article im reading about the link between type 2 diabetes and alzheimers, it says there is a link but doesnt go any further as to say why.", "topk_rank": 5 }, { "id": "corpus-302387", "score": 0.7292810678482056, "text": "Depression is hereditary in the sense that a family history of depression also increases your risk of depression. However, this is a correlation, not a causation. It's not like hair colour or colour blindness or other \"biological characteristics\" in the sense that there's a specific gene for it that we can trace.", "topk_rank": 6 }, { "id": "corpus-253379", "score": 0.7272136807441711, "text": "In addition to the comments above, I would like to add that while all Alzheimer's patients show some form of plaque formation upon autopsy, some non-Alzheimer's (ie neurologically healthy) individuals also show plaque aggregation without other disease presentation, indicating that plaque formation is in and of itself not the root cause of Alzheimer's.", "topk_rank": 7 }, { "id": "corpus-318026", "score": 0.7239460349082947, "text": "Yes and Yes. There have been some genetic associations to obesity that are inherited (associations that are not necessarily causal), but familial factors like learning poor eating habits are seen in most, if not all, obese patients, and will compound the problem in patients who could have a genetic susceptibility to obesity.", "topk_rank": 8 }, { "id": "corpus-1996964", "score": 0.7238101363182068, "text": "My dad was officially diagnosed with ALS 4 months ago, though he's been having signs for the last 2.5 years. Recently, he decided to get tested for the SOD1 gene mutation. I know that in 10% of cases, ALS can be hereditary and after talking to him recently it seems like other members of his family \\*may\\* have had similar signs as him (what he described as a \"family curse\" I interpret as a possible autosomal dominant inheritance pattern). I'm trying to confirm more of our family history right now, but it's tough since everything is passed down by word of mouth, and his side all lives in another country thousands of miles away. \n\nMy questions are: \n\n* If he comes back as positive for a mutation, how should I decide whether or not to also get tested? (I'm only 23 and quite healthy)\n* This is a ways off for me, but if you knew that your children would have ALS one day, would you still want to have them? (I realize this is also an ethical quandary)\n\nI know these are very personal and scary questions that everyone will answer differently, but I'm just trying to wrap my head around everything right now. I hate this disease and I feel really scared and worried for my dad, my brother, and myself.", "topk_rank": 9 }, { "id": "corpus-313389", "score": 0.7224346399307251, "text": "You could ask the same question about most of the leading causes of death. Why does heart disease still exist? Why does Alzheimer's? For your reasoning to work, the cause of death would need to kill a person prior to their reproductive years or otherwise cause them to have fewer offspring. A genetic predisposition to dying of breast cancer at 55 doesn't stop you from passing on that predisposition to as many kids as you want. Also, you have to assume that these diseases have a strong genetic component. While there are certainly hereditary conditions which predispose people to cancer, heart disease, and Alzheimer's, these are the minority. Genetics still play a role determining risk in many cases, but it is not as simple as one or two dominant or recessive alleles. There is a complex interplay of the genetic predisposition and environmental factors to consider.", "topk_rank": 10 }, { "id": "corpus-269478", "score": 0.7205325961112976, "text": "There are genetic links that may predispose people to certain conditions, [alcoholism](_URL_0_) being one of them. There are several genes that have been shown to influence alcohol dependence, indicating a polygenic inheritance. The reference I linked also hypothesizes that epigenetic factors can play a significant role and that gene/environment interactions are a part of the puzzle. A child with a family history of alcoholism is more likely to develop it than a child without a family history regardless if the child is removed.", "topk_rank": 11 }, { "id": "corpus-304632", "score": 0.7185670137405396, "text": "This isn't an answer but let me pose a question back to you -- would your question be different if we were talking about something like Alzheimer's disease instead of bipolar disorder? If so, why?", "topk_rank": 12 }, { "id": "corpus-253173", "score": 0.717649519443512, "text": "Having certain genes can predispose you to having an autoimmune condition. It is not as clear-cut as, say, sickle cell anemia, which is autosomal recessive (two copies of the gene -- > you get the disease no matter what). Many autoimmune diseases have certain HLA types associated with them (HLA B27, HLA DQ4, for examples), but there is an environmental component to them as well. There are theories of molecular mimicry, where virus dna is mistaken for your own dna, which causes your body to attack itself along with the foreign dna. Overall, yes - autoimmune diseases to tend to run in families. Source: the brain of a third year medical student/ fellow autoimmune disease sufferer (me).", "topk_rank": 13 }, { "id": "corpus-1256562", "score": 0.7140927314758301, "text": "My dad's father had Alzheimer's and I am starting to notice my Dad is not as sharp as he was before. He sometimes freezes mid task, he loses his train of thought frequently now and I am starting to get worried for his mental health. If I do seek a neurologist what will he recommend. Is there anything to stop the progression? Is it also a proven genetic disease? Should he get more sleep?\nHe is 63 years old.", "topk_rank": 14 }, { "id": "corpus-262784", "score": 0.7125630378723145, "text": "If a genetic disease doesn't present itself until later in life (eg huntington's or early onset alzheimers), the disease causing allele can be passed on to their progeny. Recessive genes will always persist unless you have a pure population that has weeded them out through inbreeding. there are also situations like sickle cell anemia where the heterozygote is somewhat immune to malaria, and so the disease causing allele has been selected for.", "topk_rank": 15 }, { "id": "corpus-270786", "score": 0.7117299437522888, "text": "There are some mental illnesses that are thought to be correlated to external factors (for example, toxoplasma gondii infection of a fetus while in utero), however there's actually still a lot we don't know about mental illness. Many studies on the genetic side of psychology suggest a strong hereditary component, though.", "topk_rank": 16 }, { "id": "corpus-269750", "score": 0.7099469304084778, "text": "No. Genetics is complicated. There are many genes which can contribute to looks and health but there are biological processes which result in unique DNA sequences. One example would be crossing over. Another reason can be the gene of interest (the one which causes a disorder) is on a different chromosome than the chromosomes which contain the genetic code for physical appearances. Gene inheritance is a highly randomized process so there is no guarantee that I've inherited a mutation which my dad has even if I look a lot like him.", "topk_rank": 17 }, { "id": "corpus-1997315", "score": 0.7083356976509094, "text": "Both my maternal grandmother and grandfather had alzheimer's disease. Both stopped recognizing me when I was a teenager. My grandmother has since passed, but years before she died she didn't even have a clue where she was or basically even who she was. My grandfather, who is still alive, will barely interact with me because he thinks I'm a stranger. My father is no longer alive, so it's just my mother left. I know that genetics play a role so it scares me that both her parents suffered from it. My mother is in her early 60s. I try not to think about it much, but the occasional thought slips in my head. She's all I have for immediate family and the rest of my family lives very far away.\n\nFor those of you who have parents with alzhimer's diesease, what is it like? how do you cope?", "topk_rank": 18 }, { "id": "corpus-302507", "score": 0.7061617970466614, "text": "Neuroscience researcher here that dabbles in metabolic issues. No strong correlation than I know of. There is a correlation between insulin resistance and Alzheimer's, though, and it's pretty striking. This lead some researchers in the direction of forming and testing the hypothesis that Alzheimer's disease is a metabolic disorder of the brain, specifically a decreased insulin sensitivity of the brain. The hypothesis has been coined \"Alzheimer's as Type-3 Diabetes\". A relevant study is here: [Click for Review Paper](_URL_0_), and there is convincing support for the hypothesis. That being said -- if that's the case, it may not really help you much to be a super-genius if AD is a metabolic disorder. Probably a diet modification would be more helpful than, say, playing chess or writing computer programs when you're 70.", "topk_rank": 19 } ]

[ { "id": "corpus-325373", "score": 0.7251275181770325, "text": "One way to understand how this can be possible: visible light can travel through solid materials as well (such as windows)." } ]

[ { "id": "corpus-303001", "score": 0.688510537147522, "text": "The wavelength of light that comes out of an X-ray laser is in the tens of nanometers, versus in the hundreds of nanometers that comes out of a \"regular\" (i.e. visible wavelength) laser and versus the hundreds of millions of nanometers that came out of their fore bearer the maser (Microwave-aser). But, at the end of the day, it's all light and all the same basic mechanism.", "topk_rank": 0 }, { "id": "corpus-271764", "score": 0.6884725093841553, "text": "Light travels through the EM field. Other particles travel through their respective particle fields.", "topk_rank": 1 }, { "id": "corpus-48023", "score": 0.6883138418197632, "text": "More technical answer. Photons pass through the material because they don't have sufficient energy to excite a glass electron to a higher energy level. Physicists sometimes talk about this in terms of band theory, which says energy levels exist together in regions known as energy bands. In between these bands are regions, known as band gaps, where energy levels for electrons don't exist at all. Some materials have larger band gaps than others. Glass is one of those materials, which means its electrons require much more energy before they can skip from one energy band to another and back again. Photons of visible light -- light with wavelengths of 400 to 700 nanometers, corresponding to the colors violet, indigo, blue, green, yellow, orange and red -- simply don't have enough energy to cause this skipping. Consequently, photons of visible light travel through glass instead of being absorbed or reflected, making glass transparent. EDIT: added link. _URL_0_", "topk_rank": 2 }, { "id": "corpus-310233", "score": 0.688246488571167, "text": "I'll let [Sixty Symbols](_URL_0_) answer that. Basically, if photons have enough energy to bring electrons to a higher energy level, the photon gets absorbed (opaqueness). If the photon doesn't have enough energy to excite electrons to a higher electron level, it passes through (transparent). So, if the energy gap of a substance is too large, the photons can't be absorbed, and it appears as transparent.", "topk_rank": 3 }, { "id": "corpus-274616", "score": 0.6882222890853882, "text": "Depends what you mean. We can definitely use electromagnetic waves to tell if theres any invisible gas present (more energy would get absorbed than in a vacuum), not sure if that data could be presented through photogtaphy though. Now for IR and UV - also yes. Things coated in materials that only block light in those frequencies (like sunscreen) is invisible to our eyes but can be seen with special cameras.", "topk_rank": 4 }, { "id": "corpus-289358", "score": 0.6881861090660095, "text": "In any practical sense: this is impossible. By transmitting energy through an object your *can* determine its structure and composition. But in the case of Jupiter X-rays do not have the energy to pass through without interacting with it and being absorbed. *Perhaps* high energy particles or neutrinos could be used for the effect, but to be honest high energy particles isn't my field, X-rays are.", "topk_rank": 5 }, { "id": "corpus-248839", "score": 0.6881452202796936, "text": "I think a you can extend your rubbing of the hands analogy here. Frequency isn't how fast the electrons are travelling, or even how fast the wavefront is travelling, it's just how fast they change directions. If you reduce the distance your hands travel you can change directions more often, yet have the same velocity.", "topk_rank": 6 }, { "id": "corpus-56650", "score": 0.6881443858146667, "text": "This is a concept called [blackbody radiation](_URL_0_). Everything is always emitting light, the wavelength and intensity of that light depends on the temperature of the object. Most objects you see are relatively cold, the light they emit is low-energy infrared light. You can't see it, but you can sometimes feel it around hot objects. If an object gets very hot it begins to emit more energetic light, light that we can see. Cooler objects are deep red, turning yellow, white, and eventually blindingly blue-white as they heat up. Incredibly hot objects can move past the visible spectrum and start emitting ultraviolet light in addition to the visible light.", "topk_rank": 7 }, { "id": "corpus-294883", "score": 0.6881256103515625, "text": "Crudely you can say this comes from light and energy levels in atoms/molecules being quantized. Quantized means that the material and light only have certain allowed energy levels. It cannot be in between. When light gets absorbed by a material, the material jumps up to another energy level depending on the energy from the light (photon). Lets say a photon is approaching a lone atom. The photon has energy E_p and the atom is at energy level E_a. Can the photon be absorbed? *Only* if the atom has an energy level that equals to E_p + E_a. If not, it just passes through.", "topk_rank": 8 }, { "id": "corpus-22622", "score": 0.6880098581314087, "text": "Wireless and Radio are the same, they're both transmitted through the air as radio waves. A radio wave is essentially a form of light, but the wave length is so long our eyes can't detect it. You may not know it but our eyes can only detect a tiny bit of the total spectrum of light. [This](_URL_0_) picture illustrates how little light our eyes are able to detect, what we can see is the rainbow coloured bit and the image doesn't even show the full spectrum, only part of it.", "topk_rank": 9 }, { "id": "corpus-311790", "score": 0.6879414916038513, "text": "Light has a wavelength of a few hundred nanometers. Radio waves are a few meters long. A lens would work, but it would have to be about 10 million times larger to work how you want it to.", "topk_rank": 10 }, { "id": "corpus-277122", "score": 0.6878043413162231, "text": "Short answer: [Yes to both](_URL_0_) (that's an archived page but breaks it down better than that site's current page). You can also get IR fluorescent inks. There are pigments that react to x-rays as well, but I don't know offhand if you can readily buy them for the purpose you describe (as the obvious problem, how many people have a convenient x-ray source for viewing them?). Edit: There is also \"visible light\" fluorescence, but it's hard to see under normal (white-light) conditions. For example, rubies fluoresce bright red under visible-violet illumination. The Dayglo-type inks take advantage of that effect to make certain colors much brighter than they \"should\" be under white light.", "topk_rank": 11 }, { "id": "corpus-82879", "score": 0.6876974105834961, "text": "They're just light waves; the same light you can see with your eyes, but in colors your eyes can't see. Different \"colors\" are good for different things. The color \"radio\" is good for passing through walls and traveling long distances. \"Red radio\" is especially good at things like music and walkie talkies. \"Blue radio\" is more focued and sharper and is better and stuff like cell phones and WiFi. Another color is the color \"Microwave.\" When you shine this color at water, the water heats up, so we use it to make our food warm. Most of the colors you can't see in everyday life are colors of radio or microwave, but not all of them. Our atmosphere actually blocks most of the light waves that aren't radio or visible colors.", "topk_rank": 12 }, { "id": "corpus-82347", "score": 0.6875113248825073, "text": "Well, they don't vibrate molecules in the same way sound does. Radio and microwave waves are waves within the electromagnetic field. These are fundamentally different things.", "topk_rank": 13 }, { "id": "corpus-70101", "score": 0.6873019337654114, "text": "They do, only in a very low intensity. [Here](_URL_1_) you can see the spectral distribution of a typical incandescent lamp. This spectral distribution is similar to the distribution of [black body radiation](_URL_0_) at ~~500K~~ 2700K. (Thanks to /u/Chel_of_the_sea for pointing out my error) X-rays range from 0.01 to 10 nanometers, which is at the left end of the distribution. As you can see, the intensity does not quite reach zero on that end, so x-rays will be emitted in a very low intensity.", "topk_rank": 14 }, { "id": "corpus-299004", "score": 0.6872937679290771, "text": "Photons don't move up and down, so higher frequencies don't mean they move up and down faster. The up and down oscillation is the oscillation of the electric field, the photons travel perpendicular to that. So while the electric fields oscillate at different \"speeds\", the photons travel at the same velocity.", "topk_rank": 15 }, { "id": "corpus-257260", "score": 0.6870571970939636, "text": "Light and sound waves are completely independent from one another. Light is an electromagnetic wave, which doesn't require any medium to travel, while sound is a compression wave, which does. If there *is* any difference in audio reflective properties due to different paint colors, it would be due to the physical properties of the paint and the chemical differences between the two tints. It's not due to light.", "topk_rank": 16 }, { "id": "corpus-3952", "score": 0.6869369745254517, "text": "All objects emit some radiation, as objects get hotter, the frequency of the radiation gets higher. Objects that are around room temperature emit radiation that has a lower frequency than we can see. As the objects get hotter, the frequency goes up until we can see it as red, then yellow, all the way up to blue. This might lead you to think that eventually really hot objects will emit only ultraviolet radiation that we can't see. However, objects don't emit just one frequency of radiation, they emit an entire range. The strongest frequency might be red, purple, or in the ultraviolet range, but there are always other frequencies emitted, most below the strongest frequency. So even if the strongest frequency is above our visible range, frequencies in our visible range are still emitted, so an object will never \"disappear\" because it's too hot.", "topk_rank": 17 }, { "id": "corpus-295153", "score": 0.6869351863861084, "text": "It's more of an engineering problem than anything else. Below 0.1 THz you're firmly in the realm of electronic detectors and emitters using electrons moving or being moved along a wire to generate or detect a signal. Above 10 THz you're in the realm of optics using LEDs and semiconductor lasers to emit and photodiodes to detect. In between the two regimes we haven't yet found suitable materials to generate or detect those frequencies but some inroads are being made, e.g. _URL_0_ (paywalled, sorry, but you can still read the abstract.)", "topk_rank": 18 }, { "id": "corpus-285153", "score": 0.6868152022361755, "text": "All are electromagnetic radiation. Thermal aka infrared radiation is emitted by things that are hot, but not hot enough to glow visibly. Radio waves have a much lower frequency.", "topk_rank": 19 } ]

[ { "id": "corpus-325374", "score": 0.7398840188980103, "text": "There are different types of water throughout the Earth. For instance, the Great Lakes are a Type II water. This means it's has 3 particular color producing agents (CPAs). These are chlorophyll (providing blue and green colors) , dissolved organic matter (providing dark yellow/tan/brown color), and suspended minerals/sediment (providing a red to deep brown color depending on the sediment type). So, you will get water color based on the individual concentration of each of these CPAs. For ocean waters there may be different levels or types of CPA, but I know in coastal regions of the oceans the three i mentioned are common, esp chlorophyll. On mobile so I can't get sources, however I am a freshwater remote sensing professional. Edit: here is a book on remote sensing of coastal waters _URL_0_" } ]

[ { "id": "corpus-267629", "score": 0.7019791007041931, "text": "Oceans would be black instead of blue or green due to dissolved iron. Edit: entirely possible this is false. See _URL_0_ below", "topk_rank": 0 }, { "id": "corpus-30502", "score": 0.7015042304992676, "text": "The colour of the water will be heavily affected by what is suspended in it. Colder waters tend to be rich in nutrients, with lots of plant and animal plankton, which is why whales and other animals prefer to feed in them, as opposed to tropical waters which have less. Nearby rivers enter the sea can also sweep sediment into the water, colouring it differently.", "topk_rank": 1 }, { "id": "corpus-321952", "score": 0.7007207274436951, "text": "Water isn't colourless. It looks blue because it weakly absorbs red light. In oceans, there's also a large amount of dissolved minerals and particles that add to the scattering of light. In a glass, it looks colourless because the sample is thin enough that you don't notice the blue colour. _URL_0_", "topk_rank": 2 }, { "id": "corpus-89398", "score": 0.6993181705474854, "text": "Water primarily absorbs light towards the red end of the spectrum. It reflects and scatters blues and greens. So when sunlight (a combination of all colors) hits the water, the blues are what get reflected into your eye.", "topk_rank": 3 }, { "id": "corpus-226392", "score": 0.698925256729126, "text": "There's a recent RadioLab on this, I believe. The claim, as I recall, is that the sea being \"blue\" is at least partially convention.", "topk_rank": 4 }, { "id": "corpus-25523", "score": 0.6989097595214844, "text": "If you notice the areas with clear waters, they are tropical and are usually on the east coast of a continent. That's actually because the way water flows around the equator stacks up warm oceanic water along the east coast of continents. Along the west coast, and at more extreme latitudes, the water is coming from the local area and is full of sediments. By getting all of the clean oceanic water, the east coasts get water that has had the sediments settled out of it. (Edit: Typo.)", "topk_rank": 5 }, { "id": "corpus-145352", "score": 0.6973883509635925, "text": "In some ocean areas (like the tropics) coral reefs filter the water. The living coral consumes detritus (nutrients in the water) making it hard for floating algae and plankton to live there, as they have very little in the water column to eat. Thus, water is clear. In areas where there is little or nothing consuming nutrients out of the water, plankton and algae can grow, and this clouds the water. Another example: Zebra mussels have invaded the great lakes in the USA and have been filtering the water much like coral do. As a result the water is much clearer now. _URL_0_ There is more to it then this, but that's the basics.", "topk_rank": 6 }, { "id": "corpus-316235", "score": 0.6958874464035034, "text": "Water *looks* blue because water *is* blue! [It absorbs other wavelengths of light more than blue light](_URL_0_), just not very noticeably until you have a lot of it. If you've ever been scuba diving, you won't be able to see the color red very well after 30 feet or so because it's absorbed more readily than the other colors. (Of course, if you have your own light, you can provide fresh, unabsorbed red photons to see red with.) Things dissolved in the water make a difference, too, of course, but even pure water will appear blue in white light if you have enough of it.", "topk_rank": 7 }, { "id": "corpus-3231", "score": 0.6957740187644958, "text": "Tropical waters like those in the Caribbean are warm, clear, and completely devoid of nutrients. This is why life clusters around reefs, a lot of creatures eat the plankton and algae that grows on the coral, they provide food for the area The waters up north are cold, dark, dirty, and full of nutrients! The darkness is partially from dirt/mud but a large part is all the algae, plankton, and krill. These nutrient rich waters support a wide variety of animals and many animals will go to these dark waters to feed and fatten up during the summer and then return to the warm clear waters to give birth and raise their young", "topk_rank": 8 }, { "id": "corpus-99482", "score": 0.6946811676025391, "text": "[Here's](_URL_0_) an article about it. To summarize, it looks darker and shinier because it creates a smoother surface on top of the rough surface of the stone itself and reflects the light all in the same direction. The colors can also look more vibrant because the layer of water allows for more \"subsurface reflection,\" where the light penetrates the surface and eventually comes back out, which is what is responsible for the colors of the rocks in the first place.", "topk_rank": 9 }, { "id": "corpus-55926", "score": 0.694597065448761, "text": "You know when you see the ocean and there's all that blue? Or a pool in a park and it has that light blue color? That's kinda like the light from the sun getting slowed down. Have you tried to run in the water? It's hard to run in water, and we have to be careful when we swim. It is the same for light. When light has to slow down it changes blue. So when our clothes get wet the light has to slow down and get more blue. It's like mixing a little paint together and I think that's fun, don't you?", "topk_rank": 10 }, { "id": "corpus-322699", "score": 0.6942793130874634, "text": "It boils down to how much life there is in the water. That crystal clear, blue tropical water? It's pretty much dead and devoid of biomass. That murky green seawater of the Pacific Northwest, and so forth is full of plankton, algea, and other biomass. Why is this? The colder waters tend to have upwellings that deliver nutrients into the water which feed this. The other contributor is agricultural runoff from shore which also adds to the nutrient load.", "topk_rank": 11 }, { "id": "corpus-47027", "score": 0.6941846013069153, "text": "*Gray water* is waste water from cleaning like sinks, bathing, and laundry. *Black water* is waste water from plumbing like toilets. *Blue water* is ocean water out of sight of a coast. *Green water* is ocean water near a coast. *Brown water* is rivers and lakes.", "topk_rank": 12 }, { "id": "corpus-52641", "score": 0.6935088634490967, "text": "While relatively small quantities ofwater appear to be colorless, the slight tint of water becomes a deeper blue as the thickness of the observed sample increases. The blue hue of water is an intrinsic property and is caused by the selective absorption and scattering of white light.", "topk_rank": 13 }, { "id": "corpus-646254", "score": 0.691922128200531, "text": "Like just take a grey shirt and wash it, and it will appear to be a much darker shade of grey if not completely black. \n\nWhat is it about water that makes objects have a much darker tone? Is it something to do with light? Something something refraction?", "topk_rank": 14 }, { "id": "corpus-175357", "score": 0.6914995312690735, "text": "The shiney surface is very efficient at reflecting the light that is bouncing off you... for example the blue sea on a clear day is because water is efficient at reflecting light so is reflecting the blue light of the sky .... hope that helps", "topk_rank": 15 }, { "id": "corpus-166315", "score": 0.6912151575088501, "text": "Two reasons: 1) Some of the light that bounces off of the surface of the object gets reflected back down by the underside of the water surface. So, it bounces of the object surface potentially multiple times before it escapes the water. That makes it look darker and more saturated. 2) the water surface reflects more like a mirror. A lot of the light goes in the same direction when bouncing off of water instead of going in all directions when bouncing off of a rough surface. So, if you stand where you can see the reflection of the light source, it will look a lot brighter than when the object was dry. More light in that specific direction means less light in all other directions. So, it's dimmer in most directions because it is brighter in one specific direction. If you want a ELI-college professor, here's a pro game dev writing a series of articles about how to simulate wet surfaces in console games. _URL_0_", "topk_rank": 16 }, { "id": "corpus-306215", "score": 0.6908295154571533, "text": "On reading this article: _URL_0_ it seems that water is intrinsically blue the deeper it goes - shallower parts might appear brownish red due to the dirt beneath and the sky above, but the water would still be blue (although it would reflect the sky somewhat, I'm not sure how much. - \" Clean water appears blue in white-tiled swimming pools as well as in indoor pools where there is no blue sky to be reflected. The deeper the pool, the bluer the water.\"", "topk_rank": 17 }, { "id": "corpus-317401", "score": 0.690297544002533, "text": "It isn't, water absorbs red light like crazy (giving it a blue hue). However, light intensity through a medium is inversely *exponentially* proportional to the distance light travels through that medium. So small samples of water might have very, very little attenuation due to their short thicknesses while larger (swimming pool or ocean) samples of water will be very strongly colored.", "topk_rank": 18 }, { "id": "corpus-67578", "score": 0.6889711022377014, "text": "As I understand it basically the conditions of the ocean by any particular beach will be more affected by the factors relating to that landmass than, say, a landmass 1000 miles away. So whatever materials flow out to sea, or the lack of materials flowing out to sea, will change the qualities of the water near a particular beach. Then there are other factors such as latitude, which changes how hot/cold the area is as well as the angle at which light strikes the water, the currents of water that might make another landmass's effluence a part of the local waters instead of others. For instance, it is relatively warm in Europe because of the gulf currents bringing warm Caribbean water to the south shores of England, that means a little of the silt changing the color of the water off the cliffs of Dover is coming out of the Mississippi river.", "topk_rank": 19 } ]

[ { "id": "corpus-325375", "score": 0.7209099531173706, "text": "follow up question, could that organ be perpetually transplanted?" } ]

[ { "id": "corpus-57749", "score": 0.6847625374794006, "text": "They're generally just kept cold to slow cellular death/decay. It's a surprisingly low tech solution that works very well, so much so that donor hearts are often transported in common beer coolers.", "topk_rank": 0 }, { "id": "corpus-15095", "score": 0.6847056150436401, "text": "It depends on the organ. As you noted, limbs will not regenerate, but bones will \"regenerate\" (kind of) if the pieces are brought back in proximity (assuming there is intact blood and nervous supplies). Bones will reshape themselves (including pieces) based on the forces applied to it (from use of that limb). Most solid organs also will not regenerate if damaged too badly (they just scar that damaged/dead tissue) or if the organ is lost to trauma. The liver is the exception to this rule. As long as there remains some functional liver left, it will regenerate itself if damaged or (partially) removed with correct and functional micro-anatomy. This is the basis for partial liver transplants, where the donor donates a piece of his/her liver to the recipient with the expectation that each piece in each person will grow back.", "topk_rank": 1 }, { "id": "corpus-303806", "score": 0.6845179200172424, "text": "More specifically, the renal artery and vein are attached to the recipients iliac vessels. The donor ureter is attached to the recipient bladder. And as the previous responder said - \"the donor suffers more than the recipient\" is incorrect. The donor does fine. The recipient, however, must endure immunosuppression. With that comes risk of infection, and side effects of drugs. Also, the recipient risks organ rejection as well as complications of the transplant itself.", "topk_rank": 2 }, { "id": "corpus-325406", "score": 0.6841306090354919, "text": "Honestly we don't possess enough knowledge to successfully transplant a brain. Its a common misconception since the enlightenment that the brain and body are \"separate\" but you have to understand that the brain also includes all your nerves that extend out from the spine to communicate with the body. Do I believe such a transplant to be possible? No but I have no definitive proof as only extensive testing could really determine if a head/brain/spine transplant could communicate with the nerves located in the recipient body. However when you consider how challenging it can be to get an \"alien\" organ to be accepted with current practices, you start to see how far off we are from a successful brain transplant.", "topk_rank": 3 }, { "id": "corpus-2597613", "score": 0.6836317777633667, "text": "I know people can donate their entire body for science and research, but what if Good Guy Greg over here wants a new arm? I don't need it when I'm gone, so why not pass it along to some other person?", "topk_rank": 4 }, { "id": "corpus-251965", "score": 0.6831405758857727, "text": "Depends on the drug. One of the key immune suppressants used for kidney transplants is rapamycin. There is a significant amount of evidence that rapamycin increases life span in otherwise healthy animals although the mechanism is not completely understood. _URL_0_ and _URL_1_ Rapamycin(well its analogs really) is used as a chemotherapy drug for a variety of cancers as well. The fact is that after you get a transplant, causes of death you are most likely to encounter are directly related to the transplant itself either transplant rejection or infection. It is difficult to establish cancer risk against this background. If you took a naive approach, it would look like cancer risk is significantly decreased, but it would be the same explanation as for Somalia where bullets decrease cancer risk, there are confounding conditions. Anyway while we know that rapamycin has benefits in animals we cannot be sure that the same holds for humans. Source: I am a cancer researcher", "topk_rank": 5 }, { "id": "corpus-59187", "score": 0.6828797459602356, "text": "Your body has a self protection system called an immune system that it's sole purpose is to kill any foreign agent in your body. After an organ transplant, the recipient will have to take immunosuppressant drugs for the rest of their life. Sometimes, those drugs don't suppress the immune system as well as it needs to.", "topk_rank": 6 }, { "id": "corpus-312564", "score": 0.6828352808952332, "text": "That's a really interesting question, according to [this paper](_URL_0_) (NOTE: if you aren't at a university it might be behind a paywall), it is possible to reuse kidney transplants. However, to minimize the risks to the second recipient, the Department of Health in the UK has some guidelines that must be followed. The paper also goes into some of the ethical questions that come up, but as long as the organ is viable and the primary recipient isn't on immunosuppressants, than it can be regifted. EDIT: [Here](_URL_1_) is a case study from Turkey where they successfully reused a transplanted Kidney. The paper also references two other papers that talk about the reuse of both hearts and livers in the discussion.", "topk_rank": 7 }, { "id": "corpus-146742", "score": 0.6828122735023499, "text": "Doctors will be able to decide which or your organs are suitable for donation. If you are fairly healthy and die in an accident that did not cause trauma to your heart, liver, etc, these will be donated. It depends on what you died of and your overall health. The hospital will alert the person in their district who is responsible for collecting organs and finding matches for them. The body will go to surgery, where doctors will remove the selected organs and they will be prepared for transport and kept cool.", "topk_rank": 8 }, { "id": "corpus-2596571", "score": 0.6826097965240479, "text": "My question comes after this comment. \n\nA few years ago my friend told me the rules are different for resuscitating organ donors.", "topk_rank": 9 }, { "id": "corpus-47362", "score": 0.6825999617576599, "text": "I'm actually in the middle of all my tests to donate one of my organs, so I had this conversation somewhat recently with my coordinator. It depends on the particular hospital and program you are using, but you absolutely can have contact between donor and recipient if both agree to it. The initial contact is organized through the transplant center, so that neither side feels \"obligated\" to talk to the other if they don't want to. If both agree, then it is off to the races. Some people choose not to, though. You have to go through _a lot_ of psychological testing to donate because they want to ensure that you aren't going to be upset if the recipient doesn't live their life in a way you feel is \"befitting\" the gift you gave them. Recipients may not want that kind of pressure, or they may not want to talk to them out of guilt or a sense of debt. It is a really personal decision and I can totally understand why people may not want to be contacted.", "topk_rank": 10 }, { "id": "corpus-2596809", "score": 0.6824221611022949, "text": "In my anatomy class today we were talking about organ trafficking. Theoretically, If one of my organs was harvested without my consent and transplanted into someone else, can I get it back?", "topk_rank": 11 }, { "id": "corpus-323787", "score": 0.6822993755340576, "text": "Depends on the type of organ transplanted and the way the test is administered. A bone marrow recipient getting a blood-based test would certainly have interesting results. Getting a cheek swab, on the other hand, probably wouldn't turn up anything of the donor.", "topk_rank": 12 }, { "id": "corpus-104726", "score": 0.6822973489761353, "text": "That's pretty complicated. I'll try. There's a lot of different parts of aging - cell death rates (and different kinds of cell death), simple decay and malfunctioning organs. When someone dies of old age, that means that something vital to live has given up - we don't actually die because of some invisible kill trigger. Now, the basis of that is genetic - humans have a potential lifespan bigger than a mouse because their genetics work that way. There is good reason for that, in evolution - but that would go too much into detail. So, tldr: it's because our organs and bodily systems really are only similar in the most basic sense.", "topk_rank": 13 }, { "id": "corpus-319985", "score": 0.6822788119316101, "text": "Depends on the organ. Livers can regenerate from a small nubin, so we would implant a small baby sized liver and it would grow. I think kidneys are implanted whole, hopefully in bigger children. These also can hypertrophy (get bigger) as needed. Hearts would be very unusual. Not sure it could work without a similar sized donor. As far as I know (not a paediatric transplant surgeon!) the goal is to delay transplant as long as possible so sizes work better. So in the heart they do a while bunch of weird operations like cutting out bad pieces and sticking vessels in weird spots, as a temporary measure. Past that, I think the odds of getting a super-specialist in here are low, but there will be tons of case reports in the literature. Just google \"paediatric transplant\" with the organ of interest", "topk_rank": 14 }, { "id": "corpus-2597671", "score": 0.6820165514945984, "text": "Not sure if time based, but if your organs can ever be returned if they're ever rejected by the new host body?", "topk_rank": 15 }, { "id": "corpus-250133", "score": 0.6820023655891418, "text": "Not sure if you're in the states or not. There is a whole bunch of red tape regarding US living organ/tissue donation when compared to organs/tissue procured post mortem. Short answer is that everything needs to be in place with compatible recipients lined up to receive the organs (because skin is technically an organ). I suppose it could be done, but I'm not sure that there is a shortage of skin like there is for more perishable organs. for a PDF with more info from the USgov site go [here](_URL_0_)", "topk_rank": 16 }, { "id": "corpus-311854", "score": 0.6817982792854309, "text": "Firstly, I'm not sure if this has ever been attempted before so it's hard to say what exactly will happen. However, for the second part of your question, it is likely that the organ will be a chimeric organ consisting of both your own cells (cells that originally made up the organ) and also recipient cells that have migrated into the organ. These cells will comprise largely leukocytes such as dendritic cells in most situations but for highly regenerative organs like the liver, it is likely that [extensive replacement of cells with those of recipient origin](_URL_0_) will occur. When you transplant the organ back to the donor, it is possible for the donor's immune system to have a response against the recipient cells found in the organ and although less likely, for the leukocytes present in the organ to initiate a [GVH response](_URL_1_). While the transplant is theoretically possible, you will probably have to take immunosuppressants at least in the beginning due to the reasons mentioned above.", "topk_rank": 17 }, { "id": "corpus-135981", "score": 0.6816651225090027, "text": "I'm pretty sure it'll retain the color because the DNA in those grafted cells won't change. Much like the palm of my left hand still grows tiny hairs years after the skin graft from my upper arm. /not a doctor, but I've been to way more than my share for skin issues", "topk_rank": 18 }, { "id": "corpus-190810", "score": 0.6816580891609192, "text": "Blood cells only live 3 months. A blood transfusion is a temporary fix to maintain blood pressure and oxygen levels until your body can catch up to replace blood lost. If the body rejects it a bit it's not a super big deal because foreign cells killed by the body get replaced. Organ transplants are for life. If your body attacks it it's very bad, because you'll die.", "topk_rank": 19 } ]

[ { "id": "corpus-325376", "score": 0.6902602910995483, "text": "Worth noting that the cells that replace those transplanted tissues are coming from stem cell reservoirs within those tissues, so they're still going to be \"transplanted.\" It's not as if the tissue identity is going to slowly revert to the genotype of the transplant patient." } ]

[ { "id": "corpus-313392", "score": 0.6553765535354614, "text": "Living related liver donor surgeries are fairly complicated. It's not like a kidney donation where you just cut the artery, vein, and ureter. It's more complicated than that, but kidneys are pretty straight forward. For a liver, they take a whole lobe, so they have to dissect away the bile duct, hepatic artery, hepatic vein, and portal vein. Your liver grows back, but it doesn't regrow the lobe, the other side just gets bigger. To donate another liver, you would need a whole lobe so you can get adequate vessels to separate from the donors. You can't do it with the liver you have left after the first donation.", "topk_rank": 0 }, { "id": "corpus-127691", "score": 0.6552361845970154, "text": "Before my transplant, my nephrologist explained it like this: The body attacks anything foreign relentlessly. Even though a patient takes immunosuppressive drugs, it's not enough to fully stave the constant attack, otherwise you'd have to shut down the entire immune system. Over time, the body begins to win that fight, and eventually breaks down the organ.", "topk_rank": 1 }, { "id": "corpus-97536", "score": 0.6552290320396423, "text": "cold reduces biochemical reactions. which means everything happens real slow. that minimizes how much tissue will degrade. time is still of the essence for transplants though.", "topk_rank": 2 }, { "id": "corpus-177594", "score": 0.654896080493927, "text": "The donors DNA is permanently a part of the recipient. In fact, the recipients body will treat the organ as a foreign agent, and will try to get rid of it. Organ recipients have to take immuno-suppressants for as long as they have the organ, and even still their body may reject the organ.", "topk_rank": 3 }, { "id": "corpus-643582", "score": 0.6545867919921875, "text": "I had a question. If organ transplant is possible why can’t the same be done to male reproductive organs?\n\nThe new penis is grafted to the old and new connections are made with the old penis. \n\nThe hunt for donors would be challenging but this could be worked around.", "topk_rank": 4 }, { "id": "corpus-72195", "score": 0.6544647216796875, "text": "It will always be the donor's cells. It can be possible to wean off of antirejection drugs as your body gets used to the new organ, but if your whole liver is replaced by a donor liver, you do not have any of your own liver cells to replicate and replace the donor cells.", "topk_rank": 5 }, { "id": "corpus-2597425", "score": 0.6544286608695984, "text": "Would the body “get used” to the transplanted organ, or would you have to stay on immunosuppressants for the rest of your life? Wouldn’t that cause serious quality of life issues?", "topk_rank": 6 }, { "id": "corpus-142604", "score": 0.6542431712150574, "text": "Your skin gets replaced by skin cells. Your hair gets replaced by hair cells. When you get a scar you have a wound. The wound gets filled by fixer cells. The fixer cells don't really have a purpose other than to fill in for the other cells that got damaged when you got the wound. So the cells that fix your scar on your arm aren't specific arm cells or the cells that fix your liver aren't liver cells. They are generic fixer cells. Because of that, when your cells are replaced, you get the same generic fixer cells to replace the scar cells.", "topk_rank": 7 }, { "id": "corpus-263612", "score": 0.6539492011070251, "text": "This is a little bit out of my field of expertise, but I would figure it's along the lines of blood being 'simpler' than organs. There are only a few major factors (ABO type, rhesus factor, Bombay phenotype, etc.) that affect the compatibility of blood, whereas with an organ there is a whole network of antigens and immune agents present in the transplanted tissue that won't necessarily be compatible with the target's immune system. We don't exactly autoclave and/or exsanguinate organs before transplanting them, both of those would ruin the tissue itself, so the aggravating components of the transplanted tissue are an unfortunate side-effect.", "topk_rank": 8 }, { "id": "corpus-17200", "score": 0.6537556648254395, "text": "Ahoy, fellow redditor. Yer not alone in askin', and kind strangers have explained: 1. [ELI5: Why can't you live for ever if you replace organs when they start to fail. ](_URL_1_) ^(_27 comments_) 1. [ELI5: If dying of old age is not an actual cause of death then could one live indefinitely(not immortal) provided they have enough money and a constant supply of vital body parts to replace with? ](_URL_2_) ^(_36 comments_) 1. [ELI5: If you replaced all cells and organs in your body with synthetic ones i.e nanobots, could you achieve immortality? ](_URL_3_) ^(_1 comment_) 1. [ELI5: Why can't we clone our healthy organs and replace into our damaged organs? ](_URL_4_) ^(_9 comments_) 1. [ELI5: If the human body already rejuvenates itself by replacing dead cells by new ones, then why isn't eternal life possible/happening? ](_URL_0_) ^(_49 comments_)", "topk_rank": 9 }, { "id": "corpus-289371", "score": 0.6536730527877808, "text": "Offhand, I'm going to say no, as the body will start favorably breaking down muscle tissue for protein after starvation. Tumors are identified as 'self', so unless it's a muscle tumor (which are rare), you probably won't get breakdown of it. Starved bodies are trying to maintain brain health first, and organ health second. The body doesn't start breaking down the heart during starvation. For what it's worth, caloric deprivation is not a means for reaching longevity, and this is all unrelated to transplant incompatibility.", "topk_rank": 10 }, { "id": "corpus-174607", "score": 0.653013288974762, "text": "First the claim that every cell in the body is replaced every seven years is simply a schoolyard myth. It isn't accurate so discard that misconception now. But tattoos last through the replacement of cells because the pigments which make up the tattoo do not reside within the cells themselves but rather interspersed between them. The reproduction of cells around the pigments doesn't remove the dye, it just moves a little bit and can become fuzzy.", "topk_rank": 11 }, { "id": "corpus-321981", "score": 0.6528556942939758, "text": "If I remember correctly, the danger isn't that the liver can't regrow, it's that the procedure is invasive and it carries the risk of complications for both donor and recipient in addition to organ rejection. Infections, for example is a complication of surgery. The generation of unwanted granulation/scar tissues can obstruct healing or make more complications later on. Assuming the procedure is successful, the full liver function should be restored after a few months, assuming there's no complications. Both the transplanted liver and the portion left behind should both regrow to normal volume.", "topk_rank": 12 }, { "id": "corpus-274993", "score": 0.6527194976806641, "text": "Not all cells in your body are dividing, so the answer is never. This is especially true of neurons. Now a slightly different question is how long does it take for the various components of the cells to be replaced like proteins and in general these can last for minutes in the case of rapidly degrading proteins to months or maybe years in particularly long lived ones, but in general there is a constant destruction and replenishment if the pieces that make the cells which make your body.", "topk_rank": 13 }, { "id": "corpus-973639", "score": 0.6525232791900635, "text": "I was going to post a shower thought about this but after reading I noticed this only applies to deceased organs.\n\n\n\nAlso it appears to apply primarily to people doing the transaction. Can you get around this by using an LLC to handle the transaction?\n\nFinally, Why wouldn't life insurance companies support compensating donors if it meant keeping their clients alive longer? \n\nI understand not all operations would be profitable (ie: $50k for an organ that only has a small percentage of saving their life would be adverse) but from what I've read things like kidneys and livers are almost a 90% survival rate 5+ years", "topk_rank": 14 }, { "id": "corpus-311854", "score": 0.652035653591156, "text": "Firstly, I'm not sure if this has ever been attempted before so it's hard to say what exactly will happen. However, for the second part of your question, it is likely that the organ will be a chimeric organ consisting of both your own cells (cells that originally made up the organ) and also recipient cells that have migrated into the organ. These cells will comprise largely leukocytes such as dendritic cells in most situations but for highly regenerative organs like the liver, it is likely that [extensive replacement of cells with those of recipient origin](_URL_0_) will occur. When you transplant the organ back to the donor, it is possible for the donor's immune system to have a response against the recipient cells found in the organ and although less likely, for the leukocytes present in the organ to initiate a [GVH response](_URL_1_). While the transplant is theoretically possible, you will probably have to take immunosuppressants at least in the beginning due to the reasons mentioned above.", "topk_rank": 15 }, { "id": "corpus-314520", "score": 0.6519802808761597, "text": "The answer is: they can. It's just very difficult. The many difficulties include finding a donor, keeping the body part alive for long enough before everything can be connected, and doing the connecting. These problems are unique to each kind of body part due to the anatomy. However, as surgical techniques improve, these things become more and more possible. The first arm transplant was in 2000 (Malaysia), and the first double arm transplant was in 2008 (Germany).", "topk_rank": 16 }, { "id": "corpus-185582", "score": 0.6519581079483032, "text": "Adult liver cells are closer in design to their \"immature\" natal cells and can be triggered to regress to this state to allow for regeneration. Other organs, in the process of becoming functional as they develop in the womb and immediately after birth, take on a design that is too different from this origin state to allow regression to be triggered later. One theory as to why exactly this is, postulates that the liver is in a sense a \"simpler\" organ, with cells functioning more independently of each other, all sort of doing the same job, not really getting in each other's way and so no given cell takes on an extremely specialized design relative to any other. If the heart or the brain regenerated in the way the liver did, simply accumulating more cells with no real rhyme or reason to where or to preserving a certain shape, the result would most likely be very harmful to the function of the organ because a certain complexity and balance of functions has to be very well preserved for them to do their job.", "topk_rank": 17 }, { "id": "corpus-68387", "score": 0.6512388586997986, "text": "The reason is a a bit of both. Our organs are like machines. Machines need upkeep and repair. We have tools that can do this upkeep (replication of cells), but every time they read the manual, the instructions get a little harder to figure out (shortening telomeres on dna). After a while, the machinery can no longer be fixed properly, and things break down. Once one system breaks down, the rest of the body is put under such stress that the other systems break down too.", "topk_rank": 18 }, { "id": "corpus-169771", "score": 0.651216983795166, "text": "I'm pretty sure that a faulty cell gets duplicated, until you end up with a big clump of dead cells that fuck up your organs/etc by blocking and obstructing them. that's how tumors work anyway", "topk_rank": 19 } ]

[ { "id": "corpus-325377", "score": 0.808901309967041, "text": "You're correct. In general, the larger the radius of a star, the less dense it is. The densest normal stars are the M-dwarfs (the smallest possible stars). Obviously not counting dead stars like white dwarfs/neutron stars/black holes that are all way denser. Almost all stars with a radius larger than the Sun are going to be less dense than the Sun with very wispy atmospheres." } ]

[ { "id": "corpus-1090746", "score": 0.7644248008728027, "text": "I realize that this may go beyond the scope of ELI5... Firstly, i understand that different stars can have differing masses, and densities compared to other stars of the same size. I also understand that the age of the star is a factor in it's size vs mass &amp; density. So here is my question....\n\nThere are supermassive blackholes with masses that are billions times that of our sun (and i would presume radii that are much larger as well). There are also \"stellar\" black holes with masses that are \"only\" in the dozens of times the mass of our sun. My question is, how is it that there are stars that are supermassive, like VY Canis Majoris, and UY Scutti and have not collapsed into black holes, while at the same time there are black holes with less mass than these stars.\n\n\nnote: VY Canis majoris and UY Scutti have masses about only 30 times as massive as our sun while their photospheres extend past Jupiter. are they in their final stages of life and expanding, or are they just really really big, but with a really really low density. Could some kind of push cause these stars to become back holes, or are they going to just go supernova and end up as white dwarfs?\n\nFor those interested, here is a (quite old) video showing some stellar size comparisons: here\n\n** Please note as the video is a few years old, it is incorrect about Canis Majoris being the leargest known star. That honor is held by UY Scutti, to the best of my knowledge. Article below.\n\nScutti", "topk_rank": 0 }, { "id": "corpus-158062", "score": 0.7642659544944763, "text": "They're not, in fact some material is blown away when the star explodes, so it's lighter, but it's far denser. Objects will simply get pulled into it from a comparatively further distance from the surface, but a similar distance from the centre of mass. I'm not a physicist but I feel this is fairly accurate", "topk_rank": 1 }, { "id": "corpus-312709", "score": 0.7636763453483582, "text": "Neutron stars are dense, but they aren't actually all that heavy compared to some other stars. Neutron stars are less than 3 times the mass of our sun, and we know of stars that more than one hundred times heavier than the sun.", "topk_rank": 2 }, { "id": "corpus-276215", "score": 0.7545449733734131, "text": "Yes. For example neutron stars are very dense. About 600 million tons per cubic centimeter.", "topk_rank": 3 }, { "id": "corpus-308738", "score": 0.752344012260437, "text": "The reason stars don't collapse normally despite their massive size is because the fusion that takes place at the core provides a counteractive force that prevents gravity from pulling all the mass to the center. The key difference in a supermassive star is that even when nickle and iron start to form at the core, there is still a massive amount of material that can still be fused remaining. The core may have stopped the fusion process, but the areas surrounding the core are still fusing and still providing the necessary outward pressure which keeps the star stable for a bit longer. Eventually this runs out too though, and that is when the supermassive star collapses.", "topk_rank": 4 }, { "id": "corpus-296297", "score": 0.7520063519477844, "text": "Generally the density depends on the mass and rotation speed of the star. The exact the relationship isn't full understood. [Here's a slide presentation about it](_URL_0_)", "topk_rank": 5 }, { "id": "corpus-321063", "score": 0.742904782295227, "text": "The density of stars decreases as you move away from the galactic centre. There, stars are much closer together.", "topk_rank": 6 }, { "id": "corpus-322151", "score": 0.7421083450317383, "text": "The resolution to the problem is that the star is initially low density. Stars begin as dense clumps in molecular clouds, and a few of these clumps will happen to be very massive and have several (or even several dozen) solar masses of material gravitationally bound together. However there is no degenerate core yet, no part of the clump that is dense enough to fuse hydrogen. Once fusion begins, then the pressure increases and eventually accretion is stopped.", "topk_rank": 7 }, { "id": "corpus-287381", "score": 0.7393101453781128, "text": "> ...but I would think the density changes the closer to the core you get... That's right, just like at any other big object, the density increases the deeper you get. The core has a density of roughly 150 g/cm³. The density at the photosphere, which is usually considered the surface (note that the sun as a giant gas ball has no real edge) the density is only 10^-7 g/cm3, so it's basically a vacuum. The photosphere is the place where the sun radiates off the biggest part of visible light.", "topk_rank": 8 }, { "id": "corpus-322061", "score": 0.7347269654273987, "text": "Although a pretty rare event, they can [collide](_URL_0_), or in other words, they can get arbitrarily close. The densest regions are the galactic nuclei as well as the cores of globular clusters, in which you can have thousands of stars per cubic parsec. The core of M 32, a satellite galaxy of the Andromeda galaxy has about 5000 stars per cubic parsec, which equals one star every 2,5 lightdays or every 66 billion kilometers.", "topk_rank": 9 }, { "id": "corpus-324376", "score": 0.7280893921852112, "text": "Core temperature is the key. Larger stars have much larger temperatures in their cores. For the proton-proton chain (the primary fusion mechanism in the sun), the reaction rate is proportional to density^2 and temperature^4. So if you decrease the density of a star, you can actually maintain the same reaction rate by making it hotter. For the CNO cycle (the primary fusion mechanism for larger stars), the reaction rate is proportional to density^2 and temperature^17. This extremely strong dependence on temperature means that large stars can be much less dense than the sun while still producing more light. While red giants like Betelgeuse don't use either the PP chain or the CNO cycle in their cores, I hope I've illustrated the importance of temperature in the fusion rates of massive stars.", "topk_rank": 10 }, { "id": "corpus-325237", "score": 0.7262731790542603, "text": "I can give you part of the answer. Without anything entering the system (like meteorites) stars only ever loose mass. Each star fuses smaller elements into larger ones (Ours does Hydrogen into Helium I think). But in that fusion reaction, some mass is lost in the form of heat and light. So, the star looses mass over time. One thing to keep in mind, while the star is indeed loosing mass. It's volume and density change based on where in the stars lifecycle it is. Note, I am an Econ and Math major. So take all that I say with a grain of salt. I could be wrong on a point or two.", "topk_rank": 11 }, { "id": "corpus-258056", "score": 0.7249665856361389, "text": "Yes, but it's not the stellar density that is the problem. Fact of the matter is that the galaxy is incredible sparse, even in the center (Except for the innermost couple of pc of course). The problem is all the dust in the center of the galaxy (dust = small silicate particles). Here's an extinction map of the Milky Way: _URL_0_ Center of the image is the center of the galaxy, the edges are 180 degrees away from center, so they basically connect. It's what we see around us. That is why we look towards the north/south galactic pole (vertically, up/down) when we want to look outside the galaxy.", "topk_rank": 12 }, { "id": "corpus-312205", "score": 0.7234036326408386, "text": "Dark matter is extremely diffuse. Unlike ordinary matter, it cannot radiate light to condense into stars and planets. Therefore, it remains in large-scale halos around galaxies. The [density of dark matter](_URL_0_) near the sun is around 10^(-21) g/cm^(3) (planets and stars are close to the density of water at 1 g/cm^(3)), and dark matter is even more diffuse further away from the center of galaxies. The answer is that there is just a lot of dark matter out there, around 5x as much as ordinary matter, in extremely diffuse and large-scale halos around galaxies.", "topk_rank": 13 }, { "id": "corpus-309396", "score": 0.7216848731040955, "text": "Not significantly different. You have to remember how *empty* the galaxy is. Out here, the average stellar density is about one star per ten cubic parsecs, but even close to the galactic barycentre it's only about a hundred stars per cubic parsec. If we approximate that as a cube of stars five on a side — or 125 stars total, which is an *over*estimate by nearly half, if I remember right — that puts the stars more than half a light-year apart. The galaxy is big. We are small.", "topk_rank": 14 }, { "id": "corpus-191906", "score": 0.7210477590560913, "text": "Mass. The stars smaller than Jupiter are more massive, and denser, massive enough to actually start undergoing nuclear fusion. Jupiter just doesn't have the mass to do so.", "topk_rank": 15 }, { "id": "corpus-324095", "score": 0.7208235263824463, "text": "Relatedly, a neutron star is thought to have surface features only a few millimeters high, so it's certainly much *smoother* than the Sun: _URL_0_", "topk_rank": 16 }, { "id": "corpus-72137", "score": 0.7208114266395569, "text": "No. Some stars are smaller than the sun. Some stars are much bigger. How big a star gets just depends on how much mass there is that is being pulled together by gravity when it forms.", "topk_rank": 17 }, { "id": "corpus-292238", "score": 0.7153141498565674, "text": "The question shouldn't be \"why are black holes so dense\" but rather \"why do dense things collapse into black holes.\" Although, if the density of supermassive black holes is actually pretty low. Neutron stars form when there is enough pressure to squish the electrons and protons of atoms together to form neutrons, so this generally fits your \"empty space\" description. Objects that are too massive to form stable neutron stars will still experience this, but collapse further into a black hole.", "topk_rank": 18 }, { "id": "corpus-320089", "score": 0.715277910232544, "text": "You can get an idea from [here](_URL_0_). Basically the stronger gravity is the denser and hotter stars are, the hotter the more luminosity per unit mass.", "topk_rank": 19 } ]

[ { "id": "corpus-325378", "score": 0.7501078844070435, "text": "Not without a lot of help. What has been found so far with Martian soil is that it's sterile and very salty. So you would need to introduce all the organic stuff that makes up soil here on earth (bacteria, rhizomes, fertilizers, water and so one) and flush out the excess salts. Before you even think about growing anything." } ]

[ { "id": "corpus-261899", "score": 0.7123762369155884, "text": "No. It would be HUGE news. Some microorganisms are capable of surviving in space for a while, and so there's actually a huge effort put into sanitizing our equipment before we land it elsewhere - conceivably, a microbe of some sort could survive on Mars if it found a pocket of just the right conditions, and we'd never really be able to tell whether we put it there. But life that didn't originate on Earth hasn't been discovered in any way.", "topk_rank": 0 }, { "id": "corpus-311889", "score": 0.7097396850585938, "text": "There has been a little bit of research done on this topic. Radishes, lettuce, and wheat have been [shown to survive with little to no ill-effects](_URL_2_) following 30 minutes of rapid decompression to 1.5 kPa (ambient pressure at sea level is ~101 kPa). [Wheat](_URL_1_) and [rockcress](_URL_0_) have also been found to grow fairly well at sustained low pressures ( > 10 kPa), given some caveats. That being said, plants certainly could not survive an extended period of time in a complete vacuum. As you suggest, the lack of air would be a major factor. Additionally, the low pressure would cause the water in the growth substrate to boil and transition into a gaseous state. It is not clear what the overall long-term effects of vacuum exposure on plant physiology would be. It's an active field of research and there are a *lot* of factors that could affect survival, such as matter phase changes, alteration of biochemical pathways, or rates of gas diffusion into the vacuum.", "topk_rank": 1 }, { "id": "corpus-29070", "score": 0.7094322443008423, "text": "Production of an oxygen molecule via photosynthesis requires a water molecule. Algae farms like this probably will play a crucial role in making Mars habitable, but first we need to get the temperature up it gets down to 150 below on Mars. If we could boost the temperature a bit Mars would go into a self sustaining global warming, and all of the ice on Mars would begin to melt (there's quadrillions of tonnes of water on Mars its just locked away as permafrost), once that happened plants like these could be turned loose on to the planet to do their thing.", "topk_rank": 2 }, { "id": "corpus-16129", "score": 0.7056764364242554, "text": "There's nothing stopping it from happening theoretically, but for now, NASA is trying very hard to prevent contaminating Mars with life from earth. Any kind of organisms that could be found on Mars should be studied, and if you just ship a bunch of extremophile bacteria from earth to Mars, you contaminate the planet with potentially invasive species. There might come a time where humanity will attempt to colonize a planet, but for now it's both unproductive and virtually impossible.", "topk_rank": 3 }, { "id": "corpus-73366", "score": 0.7055938839912415, "text": "No atmosphere to protect them from radiation, no nutrient rich soil for them to grow in, no viable water supply. All kinds of reasons. We can't even grow trees in the deserts here on Earth. Mars is *waaaaaaay* worse than that.", "topk_rank": 4 }, { "id": "corpus-315999", "score": 0.7036671042442322, "text": "I actually wrote my thesis along these lines I was studying Antarctic yeast species, which live in cold, dry environments and are exposed to incredible amounts of uv radiation. In other words, very similar conditions to space. Numerous studies have found that they in fact can survive in space, so it's entirely possible that other microbes could survive the trip to Mars. The yeast I studied ate rocks, do they may even be able to reproduce on Mars as well. We try to sanitize most stuff that gets sent to space, because on the off chance there is native alien life ( bacteria and what not) we don't want to accidently kill it off with an invasive species", "topk_rank": 5 }, { "id": "corpus-300116", "score": 0.702972948551178, "text": "It's quite possible that tardigrades could survive on Mars right now or with just a little bit of genetic modification. They have been exposed to the vacuum of space in for days and survived, and can live in temperatures from very close to absolute zero to over 300 degrees Fahrenheit. They are also extremely resistant to radiation.", "topk_rank": 6 }, { "id": "corpus-304922", "score": 0.7019737362861633, "text": "There are populations of bacteria within the Earths crust, several km below the surface. I see no reason why such critters would be unable to deal with conditions in an equivalent setting on Mars, especially in a more geologically active zone such as one of the volcanic centers or perhaps Valles Marineris.", "topk_rank": 7 }, { "id": "corpus-318729", "score": 0.7007638812065125, "text": "It's not _impossible_ (because that's a pretty high bar to clear) but I'd say it's very, very unlikely. The reason is time. Multicellular life didn't become common on Earth until 500-600 million years ago (EDIT: _Life_ showed up on Earth very early. But it consisted of microorganisms). There are a very few possible older fossils of very simple (think algae sheets) forms of multicellular life. This is also past the point where oxygen was common in the atmosphere. Mars never had that kind of time. When it dried out and froze, earth was still billions of years away from its first real multicellular life. For plants and animals to have shown up on Mars, they'd have had to appear much, much faster than they did on Earth. EDIT: Of course, stromatolites or other fossils resulting from single-celled organisms are more likely. I discussed the second part of the question, but fossils aren't limited to multicellular life.", "topk_rank": 8 }, { "id": "corpus-16832", "score": 0.7004374265670776, "text": "Mars lacks a functional magnetosphere to protect the planet's surface from the Sun's radiation, and the atmosphere is incredibly thin and diminishing more every day. As a result there are very few locations on Mars where bacterial life could live for a prolonged period of time. To put this in perspective, even after a full-scale nuclear war or the worst-case scenario of climate change, Earth would still be preferable to Mars for most forms of life. Mars is an incredibly hostile environment.", "topk_rank": 9 }, { "id": "corpus-245905", "score": 0.6998633742332458, "text": "You have two main problems: First, if you carry your \"life detecting experiment\" and Earth bacteria contaminate it, you may think you have seen life when really all you have seen is stuff you brought with you. Second, you might accidentally introduce an invasive species. I mean, what if Mars has native life, and we bring Earth life, and that basically eats all the Martian life. That would screw over our ability to study Martian life, and that would be bad.", "topk_rank": 10 }, { "id": "corpus-313928", "score": 0.6986693143844604, "text": "You’d have to find a way to thicken the atmosphere first. If we had bacteria or fungi that could function in a near vacuum. Add to that the problem that water boils at about 10c on Mars, and you’ve got a bit of a problem.", "topk_rank": 11 }, { "id": "corpus-644899", "score": 0.6977025270462036, "text": "I’m curious. As humans, we have developed resilience to terrestrial microorganisms (such as bacteria) in our ecosystem. If we so happen to discover “life” on Mars, and still send people there anyway, wouldn’t we be at risk to a “Martian plague” that could very well eliminate millions (if not billions) of people if those astronauts accidentally bring it back with them?\n\nIs it a major concern in Martian colonization, or is it being overlooked?", "topk_rank": 12 }, { "id": "corpus-562086", "score": 0.6970116496086121, "text": "I was thinking about the Martian and how Matt Damon survived on Potatoes. If someone wanted to do this on another planet and still live a healthy lifestyle (with moderate exercising), what else could they add to their diet to make up for what the potato lacks in nutrition? Thanks!", "topk_rank": 13 }, { "id": "corpus-320798", "score": 0.6970019936561584, "text": "Its not dumb, actually a question NASA are interested in. The main issue is not water, don't get me wrong, though that would be required, the issue is the atmosphere and the minerals present in the 'crust' of Mars, this is part of what curiosity is doing, i think it is using X-ray Diffraction to measure mineral levels. All the plants that grow on earth are acclimatised and accustomed to the specific pressure, heat and moisture that they get on earth. Also of course the obvious issue of the sun being different distances away than earth. TLDR: Water is an issue but not the main one. Plants need minerals and other metals that are present in the earth's arable soils which cause more of an issue.", "topk_rank": 14 }, { "id": "corpus-2026086", "score": 0.6965609788894653, "text": "Mars will never be earth-like. With it's weak gravity and lack of a magnetic field I fail to see how anyone is ever going to walk on the surface of Mars without a space suit.\n\nVenus on the other hand I believe has the potential to be very similar to earth. It's got the mass, it's got the magnetic field to protect it from the solar radiation. It's only real problem is that it's way too hot from global warming run amok. This extreme heat and pressure is causing all sorts of nasty problems that make the surface completely unlivable for humans.\n\nMy idea is to adjust the orbit of an asteroid (or possibly comet?) so that it is in between the Sun and Venus effectively blocking all sunlight for the planet.\n\nWould this be enough to cool the planet off after a few hundred years so that the heat and pressure reduced to the point that we could start seeding the planet with plant life that could start converting the CO2 to Oxygen?", "topk_rank": 15 }, { "id": "corpus-293721", "score": 0.6960305571556091, "text": "There is almost certainly life on Mars. Life that we sent there. We know for a fact that some organisms are capable of surviving the rigors of space (hard vacuum, radiation) because they've been found on spacecraft that have returned from the Moon. The issue is that they can only survive that way in a [spore state](_URL_0_), which is a strange 'fugue' like state that is somewhere between alive and dead. So any of the microorganisms that have survived the journey to Mars will be in a spore state. Even the spores won't last long on Mars due to the harsh environment, but some, maybe only a few, could hide in nooks and crannies of the rovers and still, technically, be alive. However, they are unlikely to ever become *viable*, i.e. reanimate and begin reproduction. This can only happen to a spore under favourable conditions, and requires the presence of water. So it's unlikely to ever happen on its own.", "topk_rank": 16 }, { "id": "corpus-310726", "score": 0.6930310726165771, "text": "The short answer is very little. You can keep a [plant in a glass jar]( _URL_0_) forever. In principle a plant could run out of CO2, but in practice a plant will survive indefinitely in a sealed jar with a bit of soil because bacteria and nematodes tend to breathe in the O2 and exhale CO2. Plants also like to have oxygen so they can use stored sugars for energy at night, but in a jar they tend to supply themselves. This works best with a jar that closes tightly filled with humidity-tolerant weedy plants that do not get very big like small ferns, dollarweed and mosses. If you use wild plants you tend to get some volunteer algae as well, and cyanobacteria (the green slime) can fix nitrogen from the air if they want to. Earth-in-a-jar is a fun little experiment. Just leave it in a windowsill.", "topk_rank": 17 }, { "id": "corpus-1705588", "score": 0.6929616928100586, "text": "I googled some of the northernmost parts of the world, and they seem to have grasses, but not many (if any) trees. So I was wondering if it's possible for plants to survive without sunlight for months at a time, maybe by going dormant or something?", "topk_rank": 18 }, { "id": "corpus-310194", "score": 0.6927891969680786, "text": "No. The atmospheric pressure on Mars is only about half a percent of Earth's atmospheric pressure. This pressure is considerably less than the [Armstrong limit](_URL_1_), where water boils at body temperature. This means your bodily fluids will start to develop bubbles ([Ebullism](_URL_0_)), which will cause death relatively quickly.", "topk_rank": 19 } ]

[ { "id": "corpus-325379", "score": 0.6925767660140991, "text": "Plants produce their own ‘sunscreen’ which consists of phenols. They have a protein called UVR8 which detects levels of UVB radiation and responds by increasing the sunscreen production. Interestingly different species of plants naturally produce different amounts of protective susncreen depending on where they originate from. Those from high altitudes/the tropics tend to produce more due to the higher levels of UVB there. This is similar to how people from Africa evolved to produce more melanin to protect themselves from the suns damage." } ]

[ { "id": "corpus-139173", "score": 0.6579364538192749, "text": "It doesn't get tan because of the sun per say, but the skin cells when exposed to large amounts of sunlight, will eventually start to produce excess melanin which is a dark pigment. Melanin will absorb light rays, which is a evolutionary adaptation to help protect the DNA in our body, from otherwise harmful radiation of the sunlight. This is why race of people from hot climates with little shade, lots of sun, naturally have darker skin.", "topk_rank": 0 }, { "id": "corpus-320377", "score": 0.6579076051712036, "text": "No. The redness of sunburn is caused by the presence of lots of blood in the skin to repair the damage from the sun. Inflammation cannot happen in the absence of circulation. On the other hand, skin damage from the sun may still occur.", "topk_rank": 1 }, { "id": "corpus-129081", "score": 0.6578938961029053, "text": "This won't be the most in-depth answer but it's kinda like this Plants and tree love sunlight. They use it in photosynthesis to create this neat stuff called glucose, which is pretty much sugar. Allows them to grow n stuff. So the higher they get the more likely they are to get sunlight, which causes this thing called phototropism, which causes the plant to grow towards wherever the sunlight comes from, in this case up.", "topk_rank": 2 }, { "id": "corpus-189040", "score": 0.6578381657600403, "text": "Biologist here! Its a protection method by our body. As the UV radiation reaches the lower levels of our skin, it tickles melanocytes, cells that basically act like photoreceptors They detect the radiation and release Melanin, a pigment that browns our skin, making it harder for UV radiation to penetrate into the soft squishy stuff our skin is meant to protect.", "topk_rank": 3 }, { "id": "corpus-153641", "score": 0.6577858924865723, "text": "It doesn't. Sunlight has the ability to bleach things by breaking down their chemical properties via radiation. This is why many plastics will yellow if left outside. But it does not have the ability to actually remove stains from clothing. Some kinds of stains will have the stain break down chemically faster than the other pigments of the cloth but this is not universal for all stains, and even when it does work it is not highly effective.", "topk_rank": 4 }, { "id": "corpus-313717", "score": 0.657667875289917, "text": "Simply because the cells are dividing more often usually. Tissue like epithelium or glandular tissue is dividing a lot. I think something like 90% of cancers are carcinomas, which are cancers derived from epithelium. Since cancer is caused by DNA mutations a cell that is dividing more often has more chance of an error occurring during replication", "topk_rank": 5 }, { "id": "corpus-166595", "score": 0.657642126083374, "text": "Your body produces Vitamin D, sunlight just stimulates it to do so. It's not \"riding\" on the light or anything like that.", "topk_rank": 6 }, { "id": "corpus-8866", "score": 0.6575166583061218, "text": "The thing about fast growing plants is that they usually have very little biomass compared to slower growing plants. Things that grow quickly would be things like corn and bamboo. Things that sequester more carbon are the things that grow more densely and more slowly. I'm no botanist, and what I know of plant genetics is that it's really *weird*. For instance, to make a miniature palm tree, you just remove some chunk of the genome, which would kill an animal zygote, but just shrinks the tree. And the thing about GMO is that we need the gene to already exist somewhere. We don't create new genes, we just take them out of one thing and stick them in another. So to make something grow more quickly we would have to rely on the mechanisms that already exist and they produce plants of low density. So it may not be a terribly effective thing to do.", "topk_rank": 7 }, { "id": "corpus-100580", "score": 0.6574966311454773, "text": "Actually, pretty much all flowers and plants move towards the sun. The idea is pretty simple, and is called Phototropism. In simplified terms, these little chemicals called \"auxins\" are at the tip of a plant when it's growing. Now, when the sun is at an angle to the tip, the auxins move to the side further away from the sun. As they are more concentrated AWAY from the sun, the side AWAY from the sun grows FASTER but the side CLOSER to the sun grows SLOWER. This causes the plant to bend towards the sun.", "topk_rank": 8 }, { "id": "corpus-188065", "score": 0.6574792861938477, "text": "Plants have a circadian rhythm, just like we do, where a molecule (CONSTANS) oscillates the same way every single day, peaking in the late afternoon. They also have a receptor called phytochrome that reacts with light. If a lot of the phytochrome is reacting at the same time that the CONSTANS is high, then the plant knows that it is a long day (spring, summer) and time to grow. If they don’t coincide, then the plant knows it’s a short day (fall, winter) and doesn’t waste energy growing. There is a whole chain reaction that actually leads to growth, but this is the basic mechanisms to distinguish if it’s growing season.", "topk_rank": 9 }, { "id": "corpus-4276", "score": 0.6574656963348389, "text": "Because your shoulders are more aimed towards the sun than your legs, which are kind of at an angle, and soak up a greater proportion of UV rays. If you laid on your back all day facing the sun, your legs and chest would then burn a lot more than your shoulders would. Imagine pointing a torch straight down at the ground, and then pointing it in front of you. Right under you is your shoulders, your legs are off in front of you, and the torch is acting as the sun. It's a lot brighter when it's not spread out more.", "topk_rank": 10 }, { "id": "corpus-324083", "score": 0.6574355363845825, "text": "Yes, there's a large variety of viruses that can attack plants. The [tobacco mosaic virus](_URL_0_) can be a particular problem since it can attack a wide range of plants. _URL_1_", "topk_rank": 11 }, { "id": "corpus-20492", "score": 0.6573578119277954, "text": "Cigarettes contain chemical which like tar which cause mutations in DNA. These mutations may cause the cell to turn cancerous. Tar and these other carcinogens are found in minuscule quantities in the air and are therefore not likely to be harmful unless specifically inhaled while smoking or by inhaling cigarette smoke.", "topk_rank": 12 }, { "id": "corpus-120960", "score": 0.6573538780212402, "text": "Because the cancer cells are your cells, but with the problem of copying uncontrollably. A lot of possible ways to kill cancer cells kill normal cells. The methods used today are pretty terrible, as they have major side effects. Cancer is not a single disease. And each of these vary based on genetics. Cancer is a fundamental problem for multicellular organisms (living things that are made of more than one cell). A living thing needs to organize, use, and control its cells. Normally a cell's cycle and behavior are tightly controlled to benefit the whole organism. A normal body generates cancerous cells, but they are usually destroyed.", "topk_rank": 13 }, { "id": "corpus-81552", "score": 0.657268226146698, "text": "Radiation isn't universally dangerous. Radiation is the name for a phenomena we witness with traveling particles of energy. These particles can be anything from visible light, to radio waves, to deadly Gamma rays. Depending on the type of radiation, the energy within the particles can be passed to your body. Light from the sun warms your skin, but also overtime can cause cancer as the energy damaged your DNA. Deadly radiation is a dose of energy so high that our bodies cannot safely process it. Our organs cook from the inside, our DNA is rapidly destroyed, and our skin potentially burned. What makes it hard is that the energy is so small it can pass right between the atoms of our bodies and be absorbed at any space between.* *very layman explanation ignoring frequency and absorption rates and criteria.", "topk_rank": 14 }, { "id": "corpus-192917", "score": 0.6572609543800354, "text": "Thin skin can sunburn way faster. Because there is less area /depth to absorb the energy. Thin skin also has less hair to protect it.", "topk_rank": 15 }, { "id": "corpus-115917", "score": 0.6572520732879639, "text": "The answer I've seen thrown around is that your body works harder to regulate body temperature when you're exposed to the sun. Don't quote me.", "topk_rank": 16 }, { "id": "corpus-313104", "score": 0.6572201251983643, "text": "That's it exactly - graphene is a giant, stable structure where everything is already bound to each other and therefore is nonreactive. PAHs, and especially their metabolites, are very reactive and can bind to DNA, causing mutations in DNA that may turn on oncogenes. Take a look at the structure of PAHs _URL_0_ and compare that to the structure of DNA bases: _URL_2_ They're pretty similar, right? They're all just made up of 5-6 carbon rings. Since they look so similar, the PAHs and their metabolites can sort of adduct themselves onto the DNA, causing damage that needs to be repaired. Everytime you have to repair something, there's a risk of not repairing it perfectly. Over a lifetime of damage and repair, you're bound to pick up some mutations that weren't repaired correctly, and some of those mutations are now oncogenes. _URL_1_", "topk_rank": 17 }, { "id": "corpus-33557", "score": 0.6572049856185913, "text": "Your genes are made of DNA. We think of DNA as a pretty static molecule, that never changes or varies once we've inherited it. As it would turn out, there are lots of chemical processes that can happen to the DNA (such as chemicals sticking to it and whatnot). These can happen at any moment in our lives and might have to do with our lifestyle. For example, having a high blood-sugar all your life might sway theses \"DNA tweaks\" a certain way. These changes are different for each cell, and can also happen in the copies of DNA that get passed on as we're discovering that it seems that sometimes these \"DNA tweaks\" can get passed on too! This means that we might be passing on effects of a certain lifestyle genetically to our kids. With their DNA pre-tweaked a certain way. It's hard to know how big the effect will be and in what way because we're still trying to understand the exact nature of these tweaks and there's also the nature vs nurture debate where we wonder if they'll have that much of an effect anyways.", "topk_rank": 18 }, { "id": "corpus-28485", "score": 0.657200813293457, "text": "Plants do this thing where they convert sugar to cellulose in order to grow. We can't digest that because we don't have the enzyme to convert it to sugars again. The plants we do eat have been cultivated over thousands of years to select for the best crop possible, and these plants tend to have a lot of sugar in sugar form like fruits, or in starch form (which we can digest back to sugar) like root vegetables. We've basically \"domesticated\" plants so that they're starchy and sugary, and recently, look pretty and big as well. The plants we don't eat are high in cellulose and not much else. Also, plants that we don't eat tend to be difficult to cultivate or only grow in specific environments that can't be brought elsewhere. Potatoes and corn? You can grow them anywhere.", "topk_rank": 19 } ]

[ { "id": "corpus-325380", "score": 0.6175783276557922, "text": "Each \"slice\" of the orange is a separate carpel, the part of the flower which produces the ovule. Each carpel contains many ovules (what becomes the seed) and many other sugar-water filled cells." } ]

[ { "id": "corpus-1707603", "score": 0.5866541266441345, "text": "Hello r/gardening!\n\nI was recently on a trip, I went to different countries in Europe and I tried this blood orange which I absolutely loved. I liked it so much I decided to bring some of the seeds to Venezuela (I live 500 m.a.s.l. in Valencia). I wanted to know if it's possible to grow the plant here, with the climate condition. And if it isn't is there any way I could \"cheat\" on nature to do so?\n\nThank you", "topk_rank": 0 }, { "id": "corpus-308116", "score": 0.5866428017616272, "text": "To add a little bit to the excellent response above, and possibly be close to the original question, some plants will increase the number of tannins in their leaves in response to and to discourage leaf eaters. _URL_0_", "topk_rank": 1 }, { "id": "corpus-308713", "score": 0.58659827709198, "text": "I can't speak to why citrus is so easy to hybridize, but I don't think it's uncommon in the plant world. As for reproduction, I believe commercially (and myself, as a hobby), citrus is propagated vegetatively. I have successfully grown a few separate meyer lemon plants and one flying dragon plant via stem cuttings. Growing plants to fruiting capability from seed takes a long time and you do not know exactly what characteristics you will get in the resulting plant. Cuttings \"self-identify\" as being as old as their donor plant, and can potentially fruit very soon. & #x200B;", "topk_rank": 2 }, { "id": "corpus-128766", "score": 0.5865141749382019, "text": "Watermelon juice is really common to see in stores. They store it in big green containers that preserve the juice really well. Once you've extracted it from the natural container though, it oxidizes easily, is more expensive to store, and has less flavor/sugar than common juices. So there's no economic benefit to storing it outside its original packaging.", "topk_rank": 3 }, { "id": "corpus-14592", "score": 0.5864766240119934, "text": "Apples are a cut-throat business. There can be dozens of different kinds in one store, and most people buy based on looks. Pears don't have that kind of competition, so they can relax and not worry about appearance as much.", "topk_rank": 4 }, { "id": "corpus-129472", "score": 0.5864710807800293, "text": "The lack of water. Same reason that any pasta is hard before it's cooked. It's just in a square shape because that's how the manufacturer decided to sell it, and it doesn't fall apart because they're all tangled in each other.", "topk_rank": 5 }, { "id": "corpus-170557", "score": 0.5862194299697876, "text": "It is due to the direction of the cut going against the muscle fibers resulting in diffraction of light into the rainbow you see. Quality isn't really part of the equation, it can happen with any quality of meat so long as the fibers are tightly packed and aligned (\"restructured\" or chopped meat bonded together won't do this).", "topk_rank": 6 }, { "id": "corpus-1660323", "score": 0.5861269235610962, "text": "People tell me half the appeal of a ShowerOrange is the biting into a raw peel and spitting it out part. But I can't do that. How else can I enhance my shower orange experience?", "topk_rank": 7 }, { "id": "corpus-93208", "score": 0.5861136317253113, "text": "It makes it much easier to isolate calorie dense portions of ingredients while removing all the fiber, water, or nutrient rich portions of ingredients, so processed food is much more likely to be empty calories. Take for example a simple process like extracting olive oil from olives. Olives have a huge amount of water (bulk that carries no calories) some protein, carbs, fiber and a relatively large amount of oil (fat). It even has a few trace minerals and some vitamins. Olive oil is 100% fat. 10g of olive oil has roughly the same amount of fat as 100g of olives. Almost every ingredient in a snack food is pure starch, sugar, or fat, with only a small amount of flavorings added. That means your eating food that has tons of calories per gram relative to something less processed even something you may consider more rich. For example, 100g of Cheetos has about 30% more calories than 100g of cheese (600 vs 450).", "topk_rank": 8 }, { "id": "corpus-305616", "score": 0.5860871076583862, "text": "Well, I think that each separated part of the oranges are in fact the result of an impregnated pistil of a singe impregnated flower on the trees that produce the orange fruit. \"The pistils of a flower are considered to be composed of carpels.[note 1] A carpel is the female reproductive part of the flower, interpreted as modified leaves bearing structures called ovules, inside which the egg cells ultimately form. A pistil may consist of one carpel, with its ovary, style and stigma, or several carpels may be joined together with a single ovary, the whole unit called a pistil. The gynoecium may consist of one or more uni-carpellate (with one carpel) pistils, or of one multi-carpellate pistil. The number of carpels is described by terms such as tricarpellate(three carpels).\" Source: _URL_1_ Image tho help understand the vocabulary or simply put a different perspective ; _URL_0_: I hope that this information is correct and that it helped you understand a little more.", "topk_rank": 9 }, { "id": "corpus-153103", "score": 0.5860175490379333, "text": "They work hard at it using every trick they can. They use plenty of water and fertilizer in very fertile ground, restrict the plant to only one fruit, baby it, and produce a large fruit which is inedible. Livestock show cattle are produced the same way. A small herd of really large bulls and cows are produced using hormones. The bulls are really sterile from the hormones. It is a game anyone with a good garden patch can play. They do it year after year. In reality we try to maximize our reward for the effort we put into it. Americans do not want large carrots, the Dutch do. Americans want sweet skinny carrots. We want normal size fruit which tastes good. So most fruit is grown for quality, not size. A tomato larger than your sandwich is not as good as two or three tomatoes which can be put on your sandwich in slices, or put on whole if small enough, sliced once, with bacon in the middle.", "topk_rank": 10 }, { "id": "corpus-1659364", "score": 0.5858498215675354, "text": "When you squeeze an orange peel, it releases oil into the air like an oil diffuser", "topk_rank": 11 }, { "id": "corpus-86712", "score": 0.5858092308044434, "text": "They can. In many cases fruit sold in stores is immature so they don't spoil during shipping. As a result the seeds don't sprout as often. Also some seeds need certain conditions before they will sprout reliably. Some need to be cold for a time and then warm to sprout -- so they will sprout in the spring, some need to dry out completely first -- so they will sprout after the dry season, and some seeds won't sprout if there's light -- so they only sprout when they get buried. Oh, and some seeds won't sprout in sugar water so the juice of the fruit stops sprouting until the fruit starts to rot.", "topk_rank": 12 }, { "id": "corpus-32633", "score": 0.5857101082801819, "text": "In some places (Chicago, New York) they are. It's merely a cultural preference; there is no scientific reason for it. Why apple pie and not peach?", "topk_rank": 13 }, { "id": "corpus-155554", "score": 0.5856319069862366, "text": "It has been proven that pruned skin provides more grip on slippery surfaces. Which has led to scientists believing that this trait was evolved for such conditions. The likely main reason for only those parts pruning up is because the rest of the body simply doesn't need the extra grip. Fingers and toes are usually the only parts of the body in contact with the surface that you're on (besides the rest of the foot and palms, but those are more about stability than grip) so it would make sense that only they prune up. Edit: the reason as to why fingers and toes are not permanently pruned is unknown", "topk_rank": 14 }, { "id": "corpus-294242", "score": 0.5856020450592041, "text": "Part of the reason is that we, like all primates, have a defective gene for producing vitamin C. Unlike dogs, cats, and nearly all other animals, we must get vitamin C in our diet or we die. The mutation must have happened to some proto-primate long ago and allowed to spread because it posed no problem for our ancestors, we lived on a diet of fruits in any case.", "topk_rank": 15 }, { "id": "corpus-67013", "score": 0.5854864716529846, "text": "Most 'rind' cheese, cheese that naturally forms a harder/protective exterior, comes in wheels because that's a good shape to get more cheese inside less rind. The rind is edible but not generally considered good eating. The wheel shape is a nice compromise between an easily transported shape and volume/surface area. Also, at this point it's just tradition. Many more modern and/or processed cheeses come in blocks that are wrapped in plastic because that's a hygienic way to get the most cheese in an easily transportable package. A rind is unnecessary and wasteful and the cheese may not be able to form a rind anyway. Even more modern cheese comes pre-shredded in plastic bags with some anti-fungal powder mixed in. Most people buy this type of cheese because it's more convenient, so it often costs less/unit than block cheese. In some cases stores only bother stocking block cheese because WIC welfare requires them to and/or won't pay for pre-shredded cheese, even though it's cheaper.", "topk_rank": 16 }, { "id": "corpus-1792366", "score": 0.5854833722114563, "text": "I just can't figure it out. Whats the point? Also, if i cut against the grain, then when its on my plate i cut it into a bite size piece but with the grain, did I just ruin the original cut? Don't bother just posting something general, I want science, specifics, and details. thanks!", "topk_rank": 17 }, { "id": "corpus-256210", "score": 0.5854323506355286, "text": "I used to manage a produce department of a grocery store, and the answer is yes. Fruits produce gas (I forget the name of it, it's been 16 years since I worked there) as they ripen, and apples produce quite a bit of it. As a matter of fact, you can put an apple in a brown paper bag with green bananas and they will ripen very quickly. The warmer the apple is, the faster it ripens and the more gas it produces. This is why apples are stored in a cool area. If you get an overripe apple (a bad one, as it were) in the barrel, it gives off quite a bit more gas and causes the other apples to ripen at a faster rate, possibly to the point of over ripening, thus spoiling the barrel. I hope this is a worthwhile answer!", "topk_rank": 18 }, { "id": "corpus-315113", "score": 0.5853122472763062, "text": "Plants don’t respond to it too well either. The best example is apples because they’re super inbred to protect the distinct flavors of each type. This makes them prone to diseases and fungus and require a lot more pesticides than other crops.", "topk_rank": 19 } ]

[ { "id": "corpus-325381", "score": 0.7128361463546753, "text": "Helium can be \"produced\" through nuclear fusion or radioactive decay. Here on earth it occurs when Uranium or other heavy elements give off an Alpha particle which then picks up an electron to become stable helium. From what I have read it doesn't sound as though \"production\" is an option. But some project to be a much higher helium reserve in the United States than what has actually been proven. Yes, we may in fact be up shit creek. Please see the occurrence production section _URL_0_" } ]

[ { "id": "corpus-71483", "score": 0.6769729256629944, "text": "I think the only hazard is asphyxiation. There could be a hazard if you stand in an enclosed space open up the valve on the helium tank, and let it displace the oxygen in the room. If you breathe it in, the low mass of the helium will allow it to escape your lungs pretty easily. It might be a little more difficult to expel it if you breathe it in while upside-down? But even in that case, coughing hard should be enough to expel most of it.", "topk_rank": 0 }, { "id": "corpus-101827", "score": 0.6768487095832825, "text": "Our sun runs on a supply of hydrogen it burns to create fuel. When the hydrogen runs out, it will begin burning the helium it contains. When the helium depletes, our sun will be out of fuel. It will crave more and slowly shrink because it is essentially malnourished. It will bear down on its own mass and without enough strength, the star will collapse on itself.", "topk_rank": 1 }, { "id": "corpus-291266", "score": 0.6767158508300781, "text": "You can, but there's no *guarantee* it's going to split nicely in half. In fact, the odds are against you. An alpha particle (a Helium-4 nucleus) has a total binding energy of roughly 28.3 MeV. Hydrogen-2 (deuterium) nuclei have an internal binding energy of just 2.2 MeV. To split a He-4 into two H-2 nuclei would require 28.3 MeV - 2\\*(2.2 MeV) = 23.9 MeV of energy. However, your other options are to split into a He-3 and a neutron, or a H-3 and a proton. To split He-4 into He-3 (binding energy: 7.7 MeV) and a neutron would require \\~20.6 MeV of energy. To split He-4 into H-3 (binding energy: 8.5 MeV) requires \\~19.8 MeV of energy. Both of these possible outcomes require *less* energy than an even split down the middle. All three of these options are, as u/RobusEtCeleritas pointed out, *highly* endothermic. 20+ MeV is a big-ol gamma ray photon. So it's going to be energetically very expensive to split each individual He-4 nuclei, and even then you're not guaranteed to slice it cleanly down the middle.", "topk_rank": 2 }, { "id": "corpus-2198681", "score": 0.6766411662101746, "text": "I'm a bit concerned about the idea of building more powerplants, due to the following reason:\n\n1. Currently, nuclear fuel is about 10% of the global electricy production\n2. At current reserves, based on 130 US$/kg, there is 6 million tons of uranium that are recoverable, which is enough for 130 years at current consumption rates\n\nIf we were to scale up nuclear energy production to something like 40%, we'd only be able to fuel the reactors for 30 years, which is a very short amount of time.\n\nAm I missing something here? Why should more powerplants be built if we can only run it for 30 more years?\n\nEdit: Thanks for all the great responses!", "topk_rank": 3 }, { "id": "corpus-307324", "score": 0.676276683807373, "text": "Yes, it would work even better with a vacuum than with helium, but you would need a very rigid shell to keep it from collapsing under atmospheric pressure. That is very, very difficult to achieve over large enough a volume without negating all the mass savings you've gained from swapping to the vacuum in the first place. Helium on the other hand is lighter than air at the same pressure, so it balances the atmospheric pressure and the balloon doesn't collapse.", "topk_rank": 4 }, { "id": "corpus-308665", "score": 0.6761568188667297, "text": "Stationary? Indefinitely? No. Neutral buoyancy? Yes. The slightest breeze or weather change would ruin the balance, and most things leak helium. As a kid I remember snapping legos on the string of helium balloons so it was just balanced. Totally doable but it won't last forever or vey long.", "topk_rank": 5 }, { "id": "corpus-321103", "score": 0.6760115027427673, "text": "In water, that might be difficult. For example, oxygen is 600 times lighter at 1 bar, meaning that you'd need a pressure of about 600 bars to make it as dense as water. But of course, at that kind of pressure, it's a liquid. And don't try to compensate by increasing the temperature: you'd just get a supercritical fluid, not a gas. [Tellurium hexafluoride has a density of about 11 kg/m³,](_URL_1_) while [ether has a density of 70 kg/m³](_URL_2_). So, in theory, at 7 bars, the former is denser than the latter. I'm not sure what happens to TeF6 at that pressure though. And I really don't want to check myself: this stuff is nasty. Edit: [Xenon is lighter than TeF6 (6 kg/m³)](_URL_0_), but, as a noble gas, it might be able to stay gaseous at 12 bar. So, maybe it's a better candidate. Or maybe radon?", "topk_rank": 6 }, { "id": "corpus-25205", "score": 0.6759825944900513, "text": "It is possible. It just takes a tremendous amount of energy - the same amount that was generated when carbon and helium fused into oxygen in the first place. Fusing a single atom of carbon and hydrogen into a single atom of oxygen produces 7.16 MeV of energy, which is a *lot* of energy. Breaking down a pound of oxygen this way would require the *input* of at least that much energy: it's [roughly that of a small nuke](_URL_0_) even if you were running the reaction at 100% efficiency.", "topk_rank": 7 }, { "id": "corpus-257111", "score": 0.6759786009788513, "text": "Basically they would have to displace an volume of air equal to the weight of their cargo, minus the weight of the helium. 70 kg of air is about 55,000 L. Helium is about 1/7th the weight of air, which brings us to about 63,000 L. A balloon is about 5 L, so that means we'd need about 1,300 of them.", "topk_rank": 8 }, { "id": "corpus-325185", "score": 0.6758447885513306, "text": "Helium actually escapes the atmosphere. Keep in mind there is no magical barrier that defines the boundary of the atmosphere - it's all held together by gravity. Helium is light enough that it floats to the top, and gravity is too weak to retain it. Also, from the thread you linked to - helium used for balloons is a very, very small percentage of total usage, so reducing that usage has next to no effect.", "topk_rank": 9 }, { "id": "corpus-298896", "score": 0.6757978200912476, "text": "If we just consider a simple single crystalline Si solar cell, we will never run out of material. Si is one of the most abundant elements on the earth. I am unsure about repairing panels but it is possible to recycle the Si. There are many other type of solar materials being researched that contain less abundant elements. Most of those materials however are more efficient absorbers and a lot less material is needed to begin with. The biggest limiting factor would be the use of indium Tin Oxide for the 'glass' coating/contact. I don't know if this is used in commercial applications but it has become fairly common in research cells. This is the same thing your touch screen is made out of and there is already work being done to find an alternative due to the cost and relatively low abundance. Edit: When I say abundance I mean in the crust. It's late and I am tired.", "topk_rank": 10 }, { "id": "corpus-175733", "score": 0.6757826805114746, "text": "A balloon expands, a tank (hopefully) does not. Helium is lighter than atmospheric air at the same pressure, but only by a factor of 5 or so, so if you put 6 times atmospheric pressure in a tank, that'll make it heavier than the surrounding air.", "topk_rank": 11 }, { "id": "corpus-290716", "score": 0.675632894039154, "text": "Absolutely, but we usually do this through a \"transfer reaction\". For example we could shoot a tritium (H-3) beam at the mercury. If we do it at the right energy, sometimes a proton will be transferred from the mercury to the tritium, and you'll get a helium and a gold atom out. These reactions are so energetic that usually they will come out of the target ionized.", "topk_rank": 12 }, { "id": "corpus-53212", "score": 0.6752595901489258, "text": "Helium is used in many industrial and medical processes - especially for cooling applications. While it is the second most prevalent element in the universe - when it is released into the atmosphere it escapes to space - gone forever. There is still helium available on earth - but obtaining it gets very expensive.", "topk_rank": 13 }, { "id": "corpus-241235", "score": 0.6750357747077942, "text": "The solar wind is matter. It is mostly protons and electrons, with some helium nuclei and trace quantities of all the other stable elements. (There's even gold in the solar wind, though of course not in commercially-interesting quantities). You can certainly capture it. At least one group wants to make use of the rather rare (on Earth) nucleus Helium-3, which is easier to fuse in a fusion reactor than is the conventional Helium-4. Catching it directly is infeasible -- people have speculated about whether it's worth trying to get it from the lunar regolith, where individual He-3 nuclei embed themselves on impact.", "topk_rank": 14 }, { "id": "corpus-273139", "score": 0.6749494671821594, "text": "Lighter gasses actually do rise to the top and escape. We're losing our helium this way. Hydrogen, too. Water vapor eventually gets broken down by UV radiation, cosmic ray particles, and the like. The hydrogen drifts upward to the upper atmosphere, where it and the helium I mentioned earlier get blown away by the solar wind.", "topk_rank": 15 }, { "id": "corpus-299975", "score": 0.6744949817657471, "text": "If you've ever had a helium balloon you'll know that, over time, even with a good material to hold it in, it will find ways to leak out of the balloon and eventually come down. Either the material the ballon is made of will have tiny imperfections allowing the gas inside to slowly leak out, or the material will degrade or be damaged with the same result. For short duration experiments this is an excellent way to get scientific equipment to high altitudes, but it wouldn't be indefinitely. Also, your equipment package will be at the whims of the air currents. If you want your equipment over certain locations or pointed in certain directions I would think a very light weight solar powered aircraft, like some of the drones used by militaries now, would be a better platform.", "topk_rank": 16 }, { "id": "corpus-277739", "score": 0.6743480563163757, "text": "I leak check high vacuum systems with He gas, the second smallest atom after H. What I can tell you is helium gets through EVERYTHING, just very slowly. That means, of course, there are little holes between the atoms in the structure of the Viton orings, aluminum flanges, steel tubes, etc, that will *eventually* allow helium in. > Everything leaks, it's just a matter of how much. -- UHV proverb Anyway, that said, there are at least hydrogen-sized holes in everything you or I have ever seen. From a physics point of view: no. Violet light, the smallest of the visible flavors, is [much bigger than a hydrogen atom](_URL_0_).", "topk_rank": 17 }, { "id": "corpus-316574", "score": 0.6743303537368774, "text": "Yes and yes. Helium becomes solid at 0.95 K with 2.5 megapascals (about 25 atmospheres) of pressure.", "topk_rank": 18 }, { "id": "corpus-294182", "score": 0.6739795207977295, "text": "Here's an outline of the proton (hydrogen) fusion chain reactions _URL_1_ Protons transmute into neutrons via beta-plus decay _URL_0_ And the collisions have too much energy to just result in a mess of helium. Fusion does happen, but so does a lot of other stuff.", "topk_rank": 19 } ]

[ { "id": "corpus-325382", "score": 0.6618070006370544, "text": "Yup, they're referred to as \"rogue planets.\" _URL_0_ Not much is known about them, they could be planets ejected from their parent stars or even objects that formed naturally without a parent star." } ]

[ { "id": "corpus-246282", "score": 0.6287129521369934, "text": "It's a [sundog](_URL_0_). [Noctilucent clouds](_URL_1_) are a related phenomenon (that's equally weird and cool).", "topk_rank": 0 }, { "id": "corpus-75586", "score": 0.6286610960960388, "text": "Orbiting happens when you continuously fall towards the planet but keep missing. Missing the planet happens because of sideways motion, you drop towards the planet a bit, but your sideways motion has taken you so far the planet is still just as far away as it was before. If you orbit too fast, you will just fling out, if you orbit too slow, you won't be able to miss the planet, your free fall ends in a crash. Now, the curious thing is, gas cloud can have momentum, that is, spinning energy. And this energy will be retained unless external force acts on the system. And in space, there aren't that many external forces. So if gas cloud spun one way, so does the star that forms from it, and so do the planets that eventually orbit it.", "topk_rank": 1 }, { "id": "corpus-285000", "score": 0.6286283731460571, "text": "> For all we know, it would be so huge that it's black body radiation would be negligible. All the power from the star has to go somewhere. The size of the sphere would determine its surface temperature based on its need to emit all that power to maintain thermal equilibrium. The outer surface of a Dyson sphere would therefore be a source just as bright as its star, just in a different part of the spectrum. To do the math, the power emitted by a sphere is proportional to surface area times is temperature to the fourth power, so we can calculate its temperature: T*_Dyson_*^4 & times; r*_Dyson_*^2 = T*_star_*^4 & times; r*_star_*^(2) T*_Dyson_* = T*_star_* & times; (r*_star_* / r*_Dyson_*)^(1/2) [Plugging in the values for the sun and 1 AU, we get a temperature of 393 K (248 & deg;F)](_URL_0_), which peaks at 7.3 micron wavelengths, in the mid-infrared spectrum. It would be much brighter than a star-sized 393 K object because of its vastly larger surface area: 46,000 times larger in our example.", "topk_rank": 2 }, { "id": "corpus-323958", "score": 0.6286240220069885, "text": "I'm not sure if there's any more recent research, but at least as of about 2006, astronomers had concluded that, in fact, most stars are singletons, not binary or higher. You can see articles on this [here](_URL_1_) and [here](_URL_0_). The studies showed that while most bright stars were in multiple star systems, there are lots of dim stars that are singletons, which tip the overall balance the other way. As for Jupiter: It's not really close in size at all to being a star. It would have to have been about 80 times bigger for fusion to start and for it to have become a star.", "topk_rank": 3 }, { "id": "corpus-5276", "score": 0.6286139488220215, "text": "Yes. There are plenty of binary star systems in the known universe. However, the planets orbiting them might not be habitable, as temperatures would likely vary greatly due to how the planet orbits the stars.", "topk_rank": 4 }, { "id": "corpus-261395", "score": 0.6285791397094727, "text": "You can use pulsars to do something like that, although that would only work within a single galaxy. In fact, the Voyager probe has a map to Earth using pulsars for triangulation.", "topk_rank": 5 }, { "id": "corpus-12983", "score": 0.6285752654075623, "text": "It would look flatter, but because the curvature of the earth is undetectable by the human eye until you are a few miles up, it would look pretty much the same. On a much smaller planet, the horizon would have a noticeable curve to it.", "topk_rank": 6 }, { "id": "corpus-312728", "score": 0.628551721572876, "text": "**Short answer:** Yes! **Long answer:** You would be broadly interested in the Messier catalog. Compiled by the French astronomer Charles Messier in 1771, the catalog contains about 100 objects that are visible in the night sky that aren't just stars. These objects include globular clusters, nebulae, and galaxies. Many of these are some of the nearest objects of their kind, and as such have been well studied with the Hubble and other telescopes. [Take a look.](_URL_0_) Our nearest galactic neighbor, Andromeda (or M31 as Messier called it) looks sorta like [this](_URL_1_) in the night sky. Can you guess which blob it is :P", "topk_rank": 7 }, { "id": "corpus-311159", "score": 0.628537654876709, "text": "If a planet is too massive, it starts to attract hydrogen from space and grows and becomes a gas giant like Jupiter. Smaller planets can maintain a rocky surface, but right now our detection methods are biased towards larger planets, so it is important to improve our investigation to detect smaller planets, so we can get a sense of how common they are and learn about how solar systems form. For example, our solar system has four gas giants, four big rocky planets, a bunch of smaller dwarf planets, and thousands of meteors and other objects. Is this normal? We don't know, because we can mainly detect big planets.", "topk_rank": 8 }, { "id": "corpus-284813", "score": 0.6285006999969482, "text": "Any planet that has become tidally-locked went though a period where its rotation was longer than it's orbit period. ~~That said, a locked planet will have a light/dark cycle that is exactly one year.~~ A locked planet would have no day/night cycle. The light/dark cycle could be longer than a year if the planet were rotating ~~slowly in the opposite orientation of its orbit~~ more slowly than the orbital period.", "topk_rank": 9 }, { "id": "corpus-274492", "score": 0.6284812092781067, "text": "It looks like a protoplanetary disk. These are generally composed of dense gas and sometimes dust [[1]](_URL_1_) [[2]](_URL_0_)", "topk_rank": 10 }, { "id": "corpus-301479", "score": 0.6284149885177612, "text": "Look at the diameters and distances here: _URL_0_ . The ratio of field of vision obscured by a spherical planet in a far circular orbit is just diam^(2)/(4*dist^(2)). If you compute that for the planets, you see the ratio is below 1e-8 for all of them - that's a millionth of a percent. Any final answer will depend on which objects you're including as \"in the solar system\", but you can see it should be pretty small regardless.", "topk_rank": 11 }, { "id": "corpus-8414", "score": 0.6283928751945496, "text": "The moon can block out the sun because it's massively closer than any planets. Sometimes that one really bright star you might see in the night sky is actually Venus. It's just a tiny point of light and it's the closest planet to the earth. Other planets in our own solar system will be even less visible than that. Planets outside of our own solar system are entirely invisible to the naked eye.", "topk_rank": 12 }, { "id": "corpus-241501", "score": 0.6283596754074097, "text": "Things that don't transfer information can go at arbitrary speeds, like shadows. The rate of recession of very distant objects is not limited by c either.", "topk_rank": 13 }, { "id": "corpus-209313", "score": 0.6283122897148132, "text": "A famous example of someone who believed in other planets and life on these planets was Giordano Bruno. He was a Dominican friar (defrocked) who was [tried and killed for heresy in 1600]( _URL_1_). Here is the exact quote, translated from Latin: > \"Innumerable suns exist; innumerable earths revolve around these suns in a manner similar  to the way the seven planets revolve around our sun. **Living beings inhabit these worlds.**\" This is from his work \"[On the Infinite Universe and Worlds](_URL_0_)\".", "topk_rank": 14 }, { "id": "corpus-244958", "score": 0.628265380859375, "text": "You've got most of it. A brown dwarf usually isn't sustaining itself at all. There may be some limited amount of fusion going on, depending on the definition, we're using, but not on the scale of stars we're used to. So you're right, that energy isn't pushing back against gravity. Degeneracy pressure works, though, and it will push back against gravity even for with larger objects - white dwarfs aren't fusing anything either, and they're many times more massive. Smaller brown dwarfs are also held up by Coulomb pressure - the atomic nuclei push each other apart because they're charged.", "topk_rank": 15 }, { "id": "corpus-27844", "score": 0.6282551884651184, "text": "Gravity keeps most of it hanging around, but some does get blown away by solar activity or whatever. I believe mars used to have a similar atmosphere but due to its lesser gravity it couldn't hold onto it.", "topk_rank": 16 }, { "id": "corpus-321387", "score": 0.6282146573066711, "text": "Most things in the universe are round-ish because of gravity, everything is being pulled to the core of the planet/star. Also spheres contain the most volume with the least amount of surface area, making them the most energy efficient shape. Asteroids are not usually round do to their small size and not having enough gravitational pull.", "topk_rank": 17 }, { "id": "corpus-312878", "score": 0.6282016038894653, "text": "Planets far away from our solar system are usually not found directly but rather indirectly. They are found by calculating the periodic dimming of the light of the star they are orbiting. When a planet travels better us and the star, we can measure the drop in it's brightness and estimate the size of the planet. The time taken to cross the star gives us it's speed and thereby it's distance from it's star. The planets in our solar system however need to be found either by direct observation it by the gravitational influence it has on other known objects this is a very hard process as planets are not self luminous and hard to spot even with the modern technology", "topk_rank": 18 }, { "id": "corpus-105006", "score": 0.628193736076355, "text": "An astronomer noticed that Io, a moon of Jupiter, appeared to have a shorter period when Earth was approaching Jupiter and a longer period when Earth was moving away. He figured the light must be moving at a finite speed to explain this. He got a damn close estimate based on working out the geometry and difference in observations.", "topk_rank": 19 } ]

[ { "id": "corpus-325383", "score": 0.6598024368286133, "text": "This is due to the ideal gas law, PV=nRT, which establishes the relationship between pressure, volume, temperature, and number of moles in an ideal gas where P=pressure, V=volume, n is the number of moles, R is the ideal gas constant, and T=Temperature. Due to the relationship between T and P, assuming the other variables, V and R, remain constant (R is a constant by definition of about 8.3 J/(K*mol)) — as T decreases P will decrease and vice versa. So in your example, when it goes from warm to cold outside, the decrease in temperature will cause a decrease in pressure. An example using 1m^3 for V and 20 moles for n: At 25C, P will equal about 7.19 psi At 5C, P will equal about 6.71 psi. Note: Low temperatures do not imply a low pressure. When evaluating pressure, all variables must be taken into consideration. However, because we are assuming volume and number of moles will remain constant, we can ‘kind of’ ignore them." } ]

[ { "id": "corpus-1964561", "score": 0.6266884207725525, "text": "So last week I got my tires rotated and balanced. Now my mileage is draining significantly more than before. Is this a common occurrence? I’ve never had that happen to any of my old cars...", "topk_rank": 0 }, { "id": "corpus-77596", "score": 0.6266055107116699, "text": "Any moving air that is colder than your body temperature will help to cool you off. Sweating helps this cooling process because evaporating water takes more energy with it, but it's not required. A gasoline engine still dissipates its heat to the atmosphere without the benefit of evaporating moisture.", "topk_rank": 1 }, { "id": "corpus-134334", "score": 0.6265713572502136, "text": "The idea is to prevent the wheels from spinning out. If you apply too much torque to your wheels (on or off ice), they will end up spinning out. However, on ice this can be achieved with far less torque than it would take to make them spin out on asphalt. Lower gears will create more torque - that's why you use them to accelerate quicker. However, this also makes you more likely to spin out, which on ice can be very dangerous. One way to prevent this is to switch to a higher gear.", "topk_rank": 2 }, { "id": "corpus-120383", "score": 0.6265437006950378, "text": "Because nothing has better insulative properties than air. A knitted blanket holds air in the spaces between the yarn threads, and your body heat warms that air up creating a shield of warm air around you. If you wrapped up in that blanket and walked outside during a blizzard, you'd freeze because the wind would replace all your warm air pockets with cold air. However, as long as you stay inside, your body should warm the the air pockets faster than the surrounding air can cool them and toastiness ensues. EDIT: I'm envisioning a crocheted afghan in the above example. Obviously knit hats are pretty warm even when it's windy outside because the spaces between threads are relatively small.", "topk_rank": 3 }, { "id": "corpus-1384974", "score": 0.6265150904655457, "text": "I mean the pressure has to remain the same from liftoff after the doors are closed. My best guess would be that there are very small leaks that change the air pressure, but that doesn't make sense because they pop pretty quickly after liftoff. A small leak couldn't cause the pressure to change that quickly.", "topk_rank": 4 }, { "id": "corpus-247369", "score": 0.6264677047729492, "text": "Its because hot air has a lower density than cool air, and this layer of hot air is concentrated near ground level. The interface of hot < > cold air causes light to refract, making objects appear distorted. Similar to how water < > air interfaces cause optical distortion.", "topk_rank": 5 }, { "id": "corpus-31971", "score": 0.6264391541481018, "text": "[Wind chill](_URL_0_) can make it feel colder than it actually is, while [high humidity](_URL_1_) can make it feel warmer than it actually is.", "topk_rank": 6 }, { "id": "corpus-8872", "score": 0.626439094543457, "text": "Because we need to have tyres that work in all weather conditions, including completely dry roads. Producing a rubber compound that was super effective in wet conditions would likely involve a fairly soft tyre surface with loads of grooves to disperse water - if that tyre were driven on dry roads, it would introduce a lot of vibration from the grooves, and the rubber compound would break down, dramatically shortening the life of the tyre.", "topk_rank": 7 }, { "id": "corpus-299285", "score": 0.6263430118560791, "text": "Sticker is one way to describe it. Ice actually exhibits \"pressure melting\" which is why it is often so slippery (a small amount of water is being made to create less friction). As the temperature gets colder the amount of pressure to cause this melting will need to increase. Since the car's weight remains the same, ice will get less slippery (and less sticky) at lower temperatures. Once agian the stickiness is caused by this \"pressure melting\" where the water thaws and refreezes (as states of matter are not referring to a single atom but rather a collection). So the \"stickiness\" is a transitioning effect between melting the ice with pressure and then it freezing back due to temperature. Source: _URL_0_", "topk_rank": 8 }, { "id": "corpus-412963", "score": 0.6263318657875061, "text": "I have a 2016 SR5 rwd, when it's cold and snowy, I get a popping noise under the driver's side seat/gas pedal area. I'm inclined to think maybe it's ice gathered some where but it's hard to tell. Does anyone else in colder climates notice this? Thanks", "topk_rank": 9 }, { "id": "corpus-57438", "score": 0.6263278722763062, "text": "Rubber balloons are obviously stretchy, but they're also porous. That's how helium leaks out - through the pores in the rubber. But in order to leak out, the helium needs pressure behind it from the helium inside the balloon. Once the balloon is deflated, there isn't any pressure pushing the helium out, so the helium remains trapped inside the rubber walls. The rubber itself is saturated with helium, so doesn't shrink to its original size. The pattern that develops is where helium is concentrated unevenly through the rubber, causing bumps and ripples on the surface. When you touch the balloon, your skin transfers heat to the rubber, which causes helium to outgas (evaporate) from the rubber, allowing the rubber to shrink closer to its original size.", "topk_rank": 10 }, { "id": "corpus-1964978", "score": 0.6263227462768555, "text": "so here's the story, had 4 new tires put on, loud hum came on immediately after. it starts at around 5o mph, and gets unbearable around 60 and goes away completely at 65...thought it was a crappy tire or low tire pressure. I checked all the pressures, they were ok, went back to sears, they \"checked\" the tires and rotated them, no change. \nI'm at a loss here, I checked for any suspension play there was none, the cv axle boots aren't torn i removed the tires and listened with a stethoscope to the wheel bearings and they seemed fine. It really does sound like bad tires, but there are no obvious defects in the side walls or the tread pattern...anyone else have a similar issue? any recommendations?", "topk_rank": 11 }, { "id": "corpus-192011", "score": 0.6263128519058228, "text": "It's dew. When the temperature drops below the 'dewpoint' the water molecules in the air can condense on to surfaces, making them wet", "topk_rank": 12 }, { "id": "corpus-186477", "score": 0.6262910962104797, "text": "It has more to do with the stability of the earth underneath the pavement than the distribution of weight on the surface. Spaces where the earth can compact faster than surrounding areas will \"sink\" faster than more densely packed earth, and the asphalt above will be less supported. It happens more frequently when weather conditions upset the foundation, like when flash flooding or sudden heavy rains saturate the ground under a paved road", "topk_rank": 13 }, { "id": "corpus-340756", "score": 0.6262566447257996, "text": "So, a question asks, if you throw an object horizontally off a building, will it produce a longer range (distance in x-direction) on a cold or hot day? The answer states on a hot day, because there is less resistance from the air that opposes the direction of velocity, which is proportional to the decreased density of the air (I guess the air becomes less viscous, with the drag force becoming smaller).\n\nThis is actually opposite to what I think would occur. I would think that the buoyancy force would be greatest on a cold day, with the density of air becoming greater and therefore the bouyancy force it provides being greater. This would lead to a longer time in the air and a greater distance traveled in the x-direction. Can someone provide input on this?", "topk_rank": 14 }, { "id": "corpus-128693", "score": 0.6262497901916504, "text": "It snows. The snow melts, and water gets in between the cracks in the asphalt. Then it gets cold again, and the water refreezes. It expands in the cracks, breaking up the asphalt. Then cars drive over it and break it up even more.", "topk_rank": 15 }, { "id": "corpus-241128", "score": 0.6262170076370239, "text": "My guess would be that if you have some flow through the system (if it's closed this would probably be from steam condensing downstream somewhere) then shutting down the header side first then you end up allowing inertia to essentially pack the downstream side tighter. If you shut the car side first you'll get the same effect in the hose, but because the header side is still open the hose gets a chance to relieve backward through the system before you have a chance to shut off the header valve. This would be similar to water hammer / hydraulic shock, though not quite to the same extreme. Does the system make a \"clunk\" when you shut either of the valves?", "topk_rank": 16 }, { "id": "corpus-43440", "score": 0.6262163519859314, "text": "Thanks for illustrating it for us! The air is the same temperature either way. The difference is how fast it's moving. It's just like how if it's 80 degrees out and windy, it feels much cooler than if it's 80 degrees out and calm. The reason that it comes out faster is that you're forcing the same amount of air through a smaller opening. It has to come out at a higher speed in order to \"keep up.\" If you're curious as to why fast-moving air feels colder, check out [this thread](_URL_1_), which is a little more simple, or [this thread](_URL_0_), which is more in-depth and informative (the guy who wrote the top comment is really smart, I hear).", "topk_rank": 17 }, { "id": "corpus-164829", "score": 0.6261924505233765, "text": "Rubber isn't completely solid. In effect it has very small holes in it, the helium leaks out of it. Some balloons are made of better materials so it happens slower.", "topk_rank": 18 }, { "id": "corpus-2014404", "score": 0.6261831521987915, "text": "I was out for two weeks and the car was parked in the garage for the whole time. I came back to a flat front tire, I have no idea why it happened. I just bought the car a few weeks ago, brand new. Please advise what should I do, I have no clue as this is my first car in US.", "topk_rank": 19 } ]

[ { "id": "corpus-325384", "score": 0.8001748323440552, "text": "Yes, it happens all the time with transition metals and you even see hypervalency with some main group elements that have d-orbitals. d-orbitals hold an additional 10 electrons. The 8 valence electron rule is a useful teaching tool for high school students to get a hang of chemistry but isn't strictly true for all atoms." } ]

[ { "id": "corpus-186347", "score": 0.759965717792511, "text": "In school, they teach you that an atom can only form as many covalent bounds as it lacks electrons to obey the Octet law (2 for Oxygen, 4 for Carbon, 1 for Fluor, 0 for Helium, etc). This is only true for the first rows: when you get to bigger elements (like sulphur), you can encounter atoms with as many covalent bounds as they have electrons on their external layer (we call them \"hypervalent\"). In SO3, sulphur forms 6 covalent bounds.", "topk_rank": 0 }, { "id": "corpus-134314", "score": 0.7572157382965088, "text": "I read u/airstew response and here is an eli5: The outer orbit of an electron has different seats available for an electron to sit in. These seats are all unique with different orbiting speeds, axis(or angle) on which it's spinning, and direction it's spinning. There are only 8 different ways these 3 criteria can exist together in an electron. Since two electrons can't sit in the same seat, an atom can only hold 8 electrons in its outer orbit.", "topk_rank": 1 }, { "id": "corpus-127226", "score": 0.7521317601203918, "text": "Only the outermost electrons are available to react. These are called valence electrons. The number of valence electrons I determined by the configuration they are in. Oxygen, for example, has 2 electrons orbiting closest to the nucleus, followed by 6 **valence electrons** orbiting at a larger distance, or higher ring. An element is considered stable when it has 8 valence electrons, also know as the octet rule. For Hydrogen and Helium, however, only 2 are needed. Edit: I didn't even answer your question! Well each element is aligned on the periotic table in such a way so that the # of valence electrons is the same as you go down the table. Hydrogen has one electron, one valence electron. Unstable. Helium has two electrons. Stable. Lithium has 3 electrons; two in the innermost orbit, one on the outermost (one valence). This trend continues on through the table, except for the metals. They're finicky.", "topk_rank": 2 }, { "id": "corpus-147668", "score": 0.7519229054450989, "text": "Hydrogen and Helium are special cases, because the first \"layer\" of electrons only fits 2. So it ends up being similar to how other elements work. Hydrogen has 1 electron and is happy to react with more hydrogen (creating H2, with two electrons) or plenty of other chemicals. Helium has 2 electrons and is \"full\" in the same way that neon is \"full\" with its 8 valence electrons - neither of them is reactive, because their valance shell is full. Once you get past those first two elements, you can start using the \"8 valence electrons\" rule as you move along the table - Lithium wants to give up its single electron, Fluorine wants to pick up one to add to its 7 and fill up, etc. It's just that the first electron shell is smaller and only fits 2.", "topk_rank": 3 }, { "id": "corpus-270391", "score": 0.7444644570350647, "text": "Simply put, the octet rule says that each atom should have an electron configuration like that of a noble gas, with 8 electrons in the valence shell. Because the oxygen atom and the carbon atoms each have 3 bonds (6 electrons) and one lone pair (2 electrons) they each have 8 electrons around them.", "topk_rank": 4 }, { "id": "corpus-264231", "score": 0.7421042323112488, "text": "There are two separate but related issues: atomic properties and nuclear stability. It is possible for large atoms to have an electron in the 8th block in the ground state, but the nucleus of that atom may be so unstable that it barely exists for any detectable time. The hypothesized \"island of stability\" around 126 may enable long-lasting larger atoms.", "topk_rank": 5 }, { "id": "corpus-832608", "score": 0.741985023021698, "text": "I'm fairly new to chemistry so please go easy on me haha.\n\nIs it possible for, lets say, sodium to gain an orbital it wouldn't normally?\n\nA neutral sodium atom would have an electron configuration of 1s2 2s2 2p6 3s1. Would it be possible to add two additional electrons so that the sodium now had a configuration of 3p1?\n\nAre orbitals formed only when we add enough electrons for a new orbital to be necessary? If so, how does this process work?\n\nSorry if this makes no sense.", "topk_rank": 6 }, { "id": "corpus-319940", "score": 0.7419726252555847, "text": "There is certainly room on the upper end of the periodic table (atomic number > 118) for more elements, but not below. An element is defined by its number of protons, so since there are only integer number of protons we have all the possible elements categorized between 1-118 protons. Above 118 protons (the limit might be higher now, I'm basing this off of a specific periodic table that might be outdated), elements presumably exist that we haven't been able to create or observe because of how quickly they decay and how much energy it requires to make them.", "topk_rank": 7 }, { "id": "corpus-286429", "score": 0.7414177656173706, "text": "I don't think you'll have much luck adding electrons due to electron-electron repulsion, but if you really *really* try you can pull off as many electrons as you want. Here's the ionization chart for [fluorine](_URL_0_), which prefers to add an electron to complete its octet. It takes over 10 times as much energy to take off the seventh electron than the first in order to go to just the 1s orbital full. Because of how destabilizing high charges are, this essentially never occurs in nature.", "topk_rank": 8 }, { "id": "corpus-262850", "score": 0.7405980229377747, "text": "If you look up electron shells, you can start to understand why certain atoms make preferential bonds with other atoms. It's energetically favorable for an atom to have a full electron shell, so an atom with 7 electrons in its outermost shell will readily bond to an atom with 1 electron, and they will resist any other atoms from joining in the molecule. Also, I'm pretty sure I've heard the Pauli exclusion principle is a reason why solid objects don't merge together. edit: _URL_0_ _URL_1_", "topk_rank": 9 }, { "id": "corpus-276545", "score": 0.7400640249252319, "text": "The numbers have to do with the number of electrons associated with each primary quantum number. If you examine [this diagram](_URL_0_), you'll see that the periodic table is grouped in blocks. The familiar 2 - > 8 - > 18 - > 32 can be found by adding up the corresponding blocks with the correct n number. So for n = 1, you only have the 1s orbital: only 2 elements have that as their valence. For n = 2, you have 2s and 2p orbitals as well, that's 2 + 6 = 8. For n = 3, you have 3s, 3p, and 3d, that's 2 + 6 + 10 = 18 For n = 4, you have 4s, 4p, 4d, 4f, that's 2 + 6 + 10 + 14 = 32. And so on. You'll see that element 118 goes 2, 8, 18, 32, 32, 18, and 8 only because it doesn't fill up the 7d, or 6f, or 5g orbitals. You can see the [expanded periodic table](_URL_1_) for some predicted elements, but many likely doesn't exist.", "topk_rank": 10 }, { "id": "corpus-12118", "score": 0.7380110621452332, "text": "It isn't quite as simple as that, and some heavier elements have more than 8 in their outer shell, but 8 is very common and I'll try to explain why. Electrons are organized into shapes called Orbitals. 2 electrons can share an orbital, each with opposite spin. The simplest orbital shape is a sphere (S orbital), so the first orbitals that fill are the spherical ones, and 2 electrons go there. The next simplest orbital shape is kinda like a figure 8 (P orbital). Imagine 2 balloons tied together by their opening/valve/pointy end. Since a figure 8 doesn't fill space fully, more than one can fit overlapping. In fact you get a figure 8 aligned with the x axis, the y axis, and the z axis. Together the shape looks just like the shape that happens if you tie 6 balloons together at the pointy end. That's 3 more orbitals, 2 electrons each for another 6 electrons in the P orbital. Once electrons fill these 8 places, they start over again filling a bigger sphere.", "topk_rank": 11 }, { "id": "corpus-177417", "score": 0.7379130125045776, "text": "Valence electrons are the electrons that take part in chemical reactions and bonding, they’re usually those in the outer most shell. Atoms form single covalent bonds by sharing two electrons between them, usually one electron comes from each atom but in some cases both electrons can come from one atom. Additionally there are double bonds which have 4 electrons shared between the atoms, and triple bonds which have 6. Yes, xenon which is a noble gas (so already has 8 valence electrons) forms certain compounds with fluorine and oxygen.", "topk_rank": 12 }, { "id": "corpus-305441", "score": 0.7361456751823425, "text": "It's all about minimising energy. Actually, *everything* is about minimising energy...for instance, things falling is because this minimises their gravitational potential energy. In the case of atoms, electrons have allowed wavefunctions that solve the equations of quantum mechanics. These rules happen to allow for 8 electrons in the valence shell in the case of most elements. When you calculate the energy, it turns out that having an extra electron to fill the shell may decrease the total energy. As above, this makes the state preferable.", "topk_rank": 13 }, { "id": "corpus-686440", "score": 0.735357403755188, "text": "So an atom is made from electrons, protons and neutrons. The amount of each determines the element. If there are 3 different \"ingredients\" for lack of a better word, you would think that there are 999 different combinations of protons, neutrons and electrons and thus 999 different elements. However that's assuming that you can only have 9 of each maximum, in reality there are millions of combinations yet only around 100 elements. Why can't we just take a carbon atom for example and shoot a few more electrons for example into it to make a new, undiscovered element. It has always pondered on my mind, genetic engineering on a molecular level.", "topk_rank": 14 }, { "id": "corpus-287041", "score": 0.7351342439651489, "text": "_URL_1_ > The octet rule is a chemical rule of thumb that states that atoms of low ( < 20) atomic number tend to combine in such a way that they each have eight electrons in their valence shells, giving them the same electronic configuration as a noble gas. The rule is applicable to the main-group elements, especially carbon, nitrogen, oxygen, and the halogens, but also to metals such as sodium or magnesium. This is one of the first things taught to students regarding the chemical structure of atoms and molecules, however it is often presented without the addendum that it is an extreme (though often useful) simplification. The next step is learning about quantum numbers. I have a link to an online lesson on it below, but if you are still in school it will be covered in senior highschool chemistry. [Quantum Numbers and Electron Configurations](_URL_0_)", "topk_rank": 15 }, { "id": "corpus-251744", "score": 0.7341597080230713, "text": "The octet rule is really only effective as a rule for the second period, and even at that, only from carbon up. Atoms in the third period have some access to the 3d orbitals, which are relatively close in energy to the 3p and 3s orbitals which are filled by the valence electrons in sulfur. This allows them to mix into [6 sp3d2 orbitals](_URL_0_) in the octahedral arrangement you see in SF6, just like how, for example, methane makes sp3 orbitals which form a tetrahedron. Oxygen does not have any d-orbitals near its valence electrons, so OF6 cannot exist.", "topk_rank": 16 }, { "id": "corpus-298718", "score": 0.7337319254875183, "text": "Depends on if you want it to be stable or not. We can create large atoms and perhaps arbitrarily large atoms but the vast majority of them decay immediately. If you're referring to relatively stable atoms, this may be worth a read: _URL_0_ e: Didn't notice the proton qualifier in your question. In that case, in a general sense you need to balance out the protons with electrons. Electrons reside in a \"shell\" (like an orbit). There's only so much room in each shell and as atoms get more protons, the additional electrons are forced into higher level shells. I think our heaviest elements have 7 shells and while it's theoretically possible to create 8 shell atoms, I think it's undetermined whether 9 shell atoms could exist so there may in fact be an upper limit.", "topk_rank": 17 }, { "id": "corpus-173507", "score": 0.7306827306747437, "text": "The concepts are sort of linked, and it’s still somewhat useful to think of orbitals in terms of shells. The shells are made up of atomic orbitals which I’m sure you know are essentially volumes of space where electrons are likely to be. Each new shell introduces a new type of orbital, that’s why each shell can hold more and more electrons. Despite it being taught, it isn’t 2,8,8,8,..., it’s actually 2,8,18,32,... The first shell only has the 1s orbital, which is why the first shell can hold 2 electrons. The second shell has the 2s and 2p orbitals (note there’s three p orbitals in a shell, from the second shell onwards), so the second shell can have 2 electrons in the 2s orbital, and 2 electrons in each of the three 2p orbitals for a total of 8 all together. Does that help somewhat? As with most things in chemistry you have to start with an easy to understand model before complicating it with reality.", "topk_rank": 18 }, { "id": "corpus-108323", "score": 0.7305900454521179, "text": "The Pauli Exclusion Principle dictates how many electrons can exist in each shell. No two electrons can have the same four quantum numbers (n, l, ml, and ms). The different numbers of electrons in each shell correspond to the number of different arrangements of those four quantum numbers. There's no simple way to explain this. But if you have a fairly firm understanding of physics, I can go into more depth. I can give the typical reasoning that you get in an introductory chemistry class, or if you're really interested I can try to explain the actual quantum mechanics behind it. Beware though, it's a mathematical nightmare.", "topk_rank": 19 } ]

[ { "id": "corpus-325385", "score": 0.7109691500663757, "text": "Paper engineer here. Paper stays together due to hydrogen bonds between the fibers. Coatings can add to the strength, but let's just talk simple, uncoated paper for this. Adding water gives additional sites to bond to and leads to the dissociation of fibers from one another as bonds go from fiber-fiber to an unsteady equilibrium of fiber-fiber and fiber-water. Edit: After thinking about it, I want to clarify that what /u/budpickens says about lubrication isn't right. The dissociation is aided by mass convection. This why an agitated tank can break down paper much quicker. It looks kind of like lubrication, but concentration gradients are a huge factor." } ]

[ { "id": "corpus-324451", "score": 0.6748402714729309, "text": "So you can think of a paper towel as being made of two things, the fibers, and the air between the fibers. These two mediums each propagate light differently, and because there is no regularity, its just a mix of air and fibers, the light scatters significantly. Why does it scatter? Well when ever light passes through a boundary between two mediums, it bends. Stick a pencil is a glass cup of water and you will see it's image \"shift\" as it enters the water. The number that describes this behavior is called the \"index of refraction.\" So the mix of air & fibers has lots of boundaries so you get lots of scattering. The oil will replace the air, and the oil is closer to the fibers in terms of index of refraction,so light feels less of a shift when passing between oil & fibers so does not scatter as much so is more transparent. Water is probably not as close, so a wet towl is more opaque.", "topk_rank": 0 }, { "id": "corpus-40858", "score": 0.674805760383606, "text": "Paper isn't sharp, it's ragged along the edge and just sort of rips it's way in rather than cutting. That's what makes it hurt, if you used a hack saw to cut yourself with it would hurt a hell of a lot more than a razor blade.", "topk_rank": 1 }, { "id": "corpus-1032665", "score": 0.6743850111961365, "text": "I've always been one to throw away the outer leaf and just use the wrap itself but I've seen a few different people keep the leaf attatched. More paper and probably harsher", "topk_rank": 2 }, { "id": "corpus-134623", "score": 0.6743340492248535, "text": "Paper is made by wood pulp dissolved in water then precipitated on a screen. When paper gets wet it loosens these pulp particles. Resulting in wrinkling or disintegration. You can try to dry pieces of paper the iron them on medium heat.", "topk_rank": 3 }, { "id": "corpus-124783", "score": 0.6739979386329651, "text": "Paper is really just wood. Wood is hard. Cutting wood with scissors quickly dulls the blades. Dull blades to not cut fabric well.", "topk_rank": 4 }, { "id": "corpus-182386", "score": 0.6738499999046326, "text": "I believe it's because as the glue dries, it loses volume and shrinks, and both the glue and paper are stuck, so it contacts and wrinkles.", "topk_rank": 5 }, { "id": "corpus-65693", "score": 0.6728501319885254, "text": "paper is made of [a bunch of tiny fibers](_URL_0_) with tiny pockets of air inside of them, which scatter light and make the paper transparent oil fils in the gaps between the fibers and stops the light from being scattered completely and allows some of it through water does the same thing, except water evaporates and oil tends to not. the difference in the refractive index of water and oil is why you can tell the difference between water spot and an oil spot on paper.", "topk_rank": 6 }, { "id": "corpus-105262", "score": 0.6721539497375488, "text": "Water is [really good at dissolving things](_URL_0_). The dried stuff will absorb some water and soften, making it easier to rub/scrape off.", "topk_rank": 7 }, { "id": "corpus-259962", "score": 0.6720397472381592, "text": "A good portion of it is due to capillary action. Capillary action is the tendency for liquids to flow without the assistance of, or in opposition to, external forces (such as gravity) in a contstrained or narrow spaces. Paper and sponges happen to be riddled with narrow spaces (paper may not seem to be, but it's a dense mat of microscopic and macroscopic fibers, which is very porous). Capillary action can also be influenced by intermolecular forces, in the case of water hydrogen bonding and dipole interactions can allow it to have a higher affinity to certain substrates. Paper and cloth happen to be made of primarily cellulose fibers, which has many polar sites along it's structure, which will interact with the water to make it \"stick\" better.", "topk_rank": 8 }, { "id": "corpus-302836", "score": 0.6711142659187317, "text": "from the wiki page on papercuts \"Paper cuts can be surprisingly painful as they can stimulate a large number of skin surface pain receptors (nociceptors) in a very small area of the skin. Because the shallow cut does not bleed very much, the pain receptors are left open to the air, ensuring continued pain. This is exacerbated by irritation caused by the fibers in the paper itself, which may be coated in chemicals such as bleach. Additionally, most paper cuts occur in the fingers, which have a greater concentration of sensory receptors than the rest of the body. The random orientation of collagen fibers in skin provides the ability to withstand pinpoint forces. However, skin does not have the same strength against shearing forces and is easily cut. The same principle can be applied to performers that stand on blades.\" I would add to that the psychological effect of anticipating pain because we expect a paper cut to hurt loads.", "topk_rank": 9 }, { "id": "corpus-56378", "score": 0.6708526611328125, "text": "When you cut paper you don't actually destroy any of the paper, it's all still there. You sheared one side away from the other. If you draw a line in felt pen, then cut with scissors right up the middle of it, this will probably look more obvious.", "topk_rank": 10 }, { "id": "corpus-35877", "score": 0.6706640720367432, "text": "Because people continue to buy inkjet. Inkjets aren't that great, [also they waste a lot of ink](_URL_0_). Buy laser printers. Also a big amount of the problem is actually the paper. Too much humidity causes the paper to cling together. Also too little humidity causes static electricity which also causes the paper to cling together.", "topk_rank": 11 }, { "id": "corpus-151967", "score": 0.6706463694572449, "text": "Also- a regular cut will bleed and lubricate the wound. A good straight cut will start to heal almost immediately because of this. A paper cut on the other hand (no pun intended) will stay dry and irritate pain receptors.", "topk_rank": 12 }, { "id": "corpus-75978", "score": 0.6705456972122192, "text": "When the rubber dries out, it no longer rubs off from abrasion on paper, and is too hard to adhere well to pencil graphite. So it's like smudging the graphite with a finger instead of a spunge. This happens due to the passage of time and dry or hot environmental conditions.", "topk_rank": 13 }, { "id": "corpus-156038", "score": 0.670204222202301, "text": "For one when the paper cuts you its generally on your hand or fingers which is a much more sensitive part of your body as it is packed with many more nerve endings Two, when you cut yourself with a knife it is straight and clean where as paper is very rough, flexable and uneven. It also leaves a very shallow wound which leaves all those nerve endings exposed to the wind, dirt, and other irritates causing the cut to hurt more than a general knife cut. Hope that answers your question!", "topk_rank": 14 }, { "id": "corpus-240751", "score": 0.6695349812507629, "text": "I'm not sure how well linking to articles is received here, but it happens that I recently read an article about the mysteries of crumpling paper. This may not answer your question directly, but it deals with many similar concepts and is a good starting point for further research. _URL_0_", "topk_rank": 15 }, { "id": "corpus-184008", "score": 0.6693493127822876, "text": "When you cut something you almost always cell rip apart cells in the process. When you break a banana, it tends to break along planes of weakness, which means the space between cells. Since you rupture much fewer cells, there isn’t as much water to spill out of the cell interior (cytosol). That’s why the broken banana is more dry around the break than a cut banana is around a cut, all other things equal.", "topk_rank": 16 }, { "id": "corpus-64003", "score": 0.6686776876449585, "text": "Before becoming wet, all of the paper fibers are neatly aligned. This allows the paper to bend predictably and smoothly Once wet, all of the fibers swell in place like individual sponges, which puts the fibers into disarray. That disarray makes its appearance to us as a stiff, wrinkly paper.", "topk_rank": 17 }, { "id": "corpus-123041", "score": 0.6684102416038513, "text": "Paper cuts cause a lot of pain because there are fibres and irregularities on the edge of the paper that make a rough cut. if you watched closely (taking away the blood) you'd see that a paper cut isn't remotely straight, like the one from a knife: it has lots of small irregularities that \"touch\" a lot of sense nerves that would otherwise be left alone.", "topk_rank": 18 }, { "id": "corpus-144068", "score": 0.6682572364807129, "text": "Think about a piece of paper dragging across the table. If the paper is dry it slides easily. It is hard and barely touches the table. There is very little friction. If the paper is wet it won't slide at all. It is soft and sticks to the table. There is a lot of friction and the paper will stop quickly. Heating the brakes softens them. It doesn't quite make them wet but they less hard and have a lot more friction, sticking a lot better. It makes breaking and other things that need friction work a lot better.", "topk_rank": 19 } ]

[ { "id": "corpus-325386", "score": 0.655122697353363, "text": "The scattering described by /u/ahhwell is called [Mie Scattering](_URL_0_) which is the reason many powders and small droplets look white. In this months Physics World there is an article about bread, which mentions amongst other things that white bread is transparent when you look at the strands of gluten under a microscope. Only the bulk scattering gives the white appearance, for the same reason." } ]

[ { "id": "corpus-269619", "score": 0.6223579049110413, "text": "The underlying principle here is blackbody radiation. The simple answer is that water never gets hot enough to emit blackbody radiation before vaporizing, at which point it is dispersed into the air and cools very rapidly. [Wien's law](_URL_0_) tells us how hot a blackbody (or to decent approximation, any common object) has to be in order to emit light at a particular wavelength. You'll see that \"red hot\" is quite a high temperature compared to the boiling point of water. However, you would find that hot water emits quite a lot of infrared light!", "topk_rank": 0 }, { "id": "corpus-59496", "score": 0.6223515868186951, "text": "It is lime. Any water contains solved amounts of lime so when it evaporates the lime reamins as residue.", "topk_rank": 1 }, { "id": "corpus-126924", "score": 0.6222177743911743, "text": "White things don't reflect all wavelengths. White things reflect all visible wavelengths, which is only a tiny portion of the whole spectrum of light. Melanin (the chemical that makes your skin darker, whether it's because you tanned or because you're naturally dark-skinned) stops ultra-violet light (light with a shorter wavelength than visible light), which normally isn't reflected by your skin, from damaging your body. It also blocks your body from using the ultra-violet light to produce vitamin D, which is why people in temperate climates, where the sun isn't as strong, evolved to have lighter skin- they didn't need the extra sun protection, but did need the vitamin D.", "topk_rank": 2 }, { "id": "corpus-40850", "score": 0.6222137808799744, "text": "the water fills the gaps in the fabric and the light can travel from water drop to water drop all the way through and not be absorbed by the fabric. Or at least I hope so, otherwise it is a sorcery of which I have never suspected.", "topk_rank": 3 }, { "id": "corpus-101789", "score": 0.6221859455108643, "text": "Your tear film has three layers: mucous, water, then a lipid layer on top. The lipid layer keeps the water from evaporating off your eyes too quickly. As you sleep, if your eyes are open even a little bit, that water layer can evaporate so when you wake up, all that is really left is mucous and the lipid layer. Without the water layer, your tear film is thicker and is more difficult to see through, hence that cloudiness. But when you blink a few times, it clears up as the lacrimal gland releases tears to add to the water layer.", "topk_rank": 4 }, { "id": "corpus-780807", "score": 0.622165858745575, "text": "Hello,\nthis is how my water looks currently.\nI use the Water And Terrain Enhancement Redux Mod and the Realvision ENB also the Enhanced Lights and FX mod. I want it to have a light blue and that i can look through it. Can anyone help me? Thanks in advance.\nEDIT: A result like this would be great", "topk_rank": 5 }, { "id": "corpus-318693", "score": 0.6221053004264832, "text": "There are many factors but here are the main ones. **Background info** The refractive index of a substance refers to how much it refracts or 'bends' light entering it. For example, glass and water have a higher refractive index than air. [A simple diagram](_URL_0_) **Reasons** 1. Water refracts light, its refractive index is very similar to that of our [cornea](_URL_1_). On land, the cornea serves an important function in refracting light so that it can be focused by the lens onto the retina - creating a clear image. In water, light hardly refracts when entering our cornea, hence the image is not properly focused on the retina. 2. In the case of 'dirty' water, there are impurities (e.g. dirt) that block light travelling through the water, resulting in an unclear image.", "topk_rank": 6 }, { "id": "corpus-239345", "score": 0.6220744848251343, "text": "These are in fact the white blood cells flowing through the capillaries on your retina. Red blood cells are much more abundant and your brain \"filters\" them out of your vision as they are good at absorbing blue light (such as light from the blue sky!), white blood cells are bigger, rarer and less red than red blood cells and so your brain has a harder time editing them out. It's called the Blue Field Entoptic Phenomenon because it happens most when looking at blue objects. _URL_0_", "topk_rank": 7 }, { "id": "corpus-306643", "score": 0.6219909191131592, "text": "Short answer: yes. Long answer: the sky is blue because shorter wavelengths of light are scattered in the atmosphere via rayleigh scattering. Since the more blue wavelengths are bounced around a lot while the more red wavelengths go strait through, the Sun appears slightly red while the sky is blue from the blue light being scattered so much that it comes from every direction. This is also true of the air between you and a distant mountain, if the air has sunlight passing through it than it will have a faint blue glow.", "topk_rank": 8 }, { "id": "corpus-124717", "score": 0.6218919157981873, "text": "[According to Don MacGorman, a physicist at the National Severe Storms Laboratory in Norman, Oklahoma: “Basically lightning stays more on the surface of the water rather than penetrating it. That’s because water is a reasonably good conductor, and a good conductor keeps most of the current on the surface.”] (_URL_0_). Also see [THIS] (_URL_1_). And [this old thread] (_URL_2_)", "topk_rank": 9 }, { "id": "corpus-113631", "score": 0.6218799352645874, "text": "I think because the sun has to travel through more of the atmosphere at that angle. And at that angle there are lots more clouds, pollutants, etc that are refracting the light and making it disperse, which only leaves oranges and reds that are strong enough to blast through all those obstacles and make it to your eyes.", "topk_rank": 10 }, { "id": "corpus-74326", "score": 0.6218793988227844, "text": "The primary factor is the thickness of atmosphere the sun's light has to pass through to reach you. At sunset, the atmosphere is the thickest, and light has the most chance to scatter the blue color away and leave the longer wavelengths -- yellow, orange, and red.", "topk_rank": 11 }, { "id": "corpus-66667", "score": 0.6218728423118591, "text": "The lines are called [Contrails](_URL_0_). It's short for condensation trails. Alot of times they are caused by the engine burning fuel and releasing water vapor along with carbon dioxide. Clouds form when there's too much water vapor, this varies by temperature. If there is enough water vapor in the air and it's cold enough there is a trail. If there is not enough water or it's warm enough, there is no trail.", "topk_rank": 12 }, { "id": "corpus-312854", "score": 0.621825098991394, "text": "> [Rayleigh scattering](_URL_1_) is inversely proportional to the fourth power of wavelength, so that shorter wavelength violet and blue light will scatter more than the longer wavelengths (yellow and especially red light). The resulting color, which appears like a pale blue, actually is a mixture of all the scattered colors, mainly blue and green. **Violet, though strongly scattered, is a minor component of the solar spectrum and is less efficiently detected by the human eye.** Conversely, glancing toward the sun, the colors that were not scattered away — the longer wavelengths such as red and yellow light — are directly visible, giving the sun itself a slightly yellowish hue. Viewed from outer space, however, the sky is black and the sun is white. [Photo here](_URL_0_) Emphasis mine.", "topk_rank": 13 }, { "id": "corpus-45750", "score": 0.6217743158340454, "text": "Ok so someone else is going to do a better job explaining this than me but I was here first. It comes down to light scattering. You know that colors are light. well when light moves through a lot of molecules that are of no color in particular it gets scattered, but only a bit, not as much as a solid object. The violet side of the spectrum has a short wavelength, and the red side has a long wavelength. So that means red is going to scatter the leads, orange a little, yellow a bit more, green more, blue a lot, and then violet (indigo isn't real) The more it gets scattered the more of it we see, and it turns out that the combination of the green, blue and violet scattered light looks pretty blue to us. You don't see that in a glass, because there is not enough molecules to have a noticeable effect compared to the color of what you are seeing on the other side of the glass.", "topk_rank": 14 }, { "id": "corpus-2413587", "score": 0.6217734217643738, "text": "so when i add unity fog, color is white, basically any snow particle that is in the fog for some reason turns black, but the color is set to white and if it is close enough to not be in the fog it works fine and shows up white. \n\n\nanyone know how to fix this?", "topk_rank": 15 }, { "id": "corpus-30860", "score": 0.6217708587646484, "text": "Because the earth and moon in that photo are much brighter than the stars, and so the camera's exposure was metered to the earth and moon, which did not allow the stars enough time to come through on the film. If you DID leave the shutter open long enough to capture the stars, then the earth and moon would just be blindingly bright white splotches.", "topk_rank": 16 }, { "id": "corpus-89505", "score": 0.6217520833015442, "text": "The clouds are not under it. Not always. In every mountain region you can sometimes see the phenomenon of a closed cloud ceiling while being above it. Cumulus clouds (thunderstorm clouds) for example can tower up to a height above 12km/40'000ft. It does snow up there.", "topk_rank": 17 }, { "id": "corpus-100341", "score": 0.6217199563980103, "text": "It's a property called adhesion - basically water molecules like to stick to other things (as well as themselves, which is another property called cohesion). It's because water molecules are polar (ie they have one side that's positively charged and one side that's negatively charged.)", "topk_rank": 18 }, { "id": "corpus-29081", "score": 0.6217138767242432, "text": "Raleigh scattering. What color is the sky? Blue. What happens if you look through a few miles of sky? It gets a blue tint.", "topk_rank": 19 } ]

[ { "id": "corpus-325387", "score": 0.6165463328361511, "text": "Polyethylene Terephthalate: Polyethylene Terephthalate (PET, PETE or polyester) is actually quite resistant to alcohol and oil. Pthalates and diethyl phthalate (DEP) are widely present illegally produced spirits/alcohol and there is some evidence of negative health risks, you would have to be drinking a lot. It's hard to type/research on my phone but here's the one I managed to go through briefly _URL_0_" } ]

[ { "id": "corpus-109935", "score": 0.5857017636299133, "text": "The mechanism in play is the same one that causes the bottom to burst off of a bottle when it is filled with water and you strike the top. Basically when you hit the bottle, the bottle moves down faster than the liquid. This causes a cavitation (vacuum) to form. Almost as quickly as the cavitation forms, the liquid quickly and violently slams down to fill it. When the bottle is filled with water, all this energy just pops the bottom of the bottle off but when the bottle is filled with a carbonated beverage, the CO2 is quickly forced out of solution. Here it is in slow motion: _URL_0_ edit: this video shows the mechanism in action in both still liquids and carbonated liquids: _URL_1_", "topk_rank": 0 }, { "id": "corpus-35677", "score": 0.585681676864624, "text": "They are there for the ejectors to unscrew the neck from the mold. They always push opposite the direction that the threads on the neck go, and they aren't on bottles that don't have threads.", "topk_rank": 1 }, { "id": "corpus-850094", "score": 0.5856778621673584, "text": "Too drunk to do the homework on this. Saw someone post about this the other day. Is it actually safe to drink? What's the alcohol content? I thought mouthwash companies removed alcohol years ago. Could use another drink and the bag of Franz has run dry. Always thought Listerine was suicide potion for homeless people.", "topk_rank": 2 }, { "id": "corpus-502892", "score": 0.585675060749054, "text": "Just a few quick questions looking to see what other people's opinions are.\n\n1. When you add fruit in your secondary do you age it with the fruit in, or do you rack it after a little while before bottling?\n2. Is there a difference between using clear and brown/colored bottles? Are there any downsides to using brown/colored bottles?", "topk_rank": 3 }, { "id": "corpus-1126436", "score": 0.5856539011001587, "text": "They’re never mentioned (as far as I have seen) when talking about the damaging nature of plastics and various industries attempts to lower usage. \n\nRight now I’m surrounded by my nephews and their endless supply of multicoloured plastics. Everything is plastic.\n\nEdit: sorry, obviously not correct when I said Single Use, more that I often see them thrown away and not recycled.", "topk_rank": 4 }, { "id": "corpus-188136", "score": 0.5856513381004333, "text": "If the glass vessel is hard to produce (ie expensive) then it may be cleaned and re-used directly. For everyday things like beer bottles the glass is cleaned, crushed into small bits, and fed back into the glass production line along with other scraps from earlier production runs. It's called 'cullet'. Minor variations (like different color, composition) are corrected for once the glass batch is fully melted.", "topk_rank": 5 }, { "id": "corpus-1593127", "score": 0.5856328010559082, "text": "I'm a beer guy, but I'm willing to try new things. I've had shots of vodka, whiskey, and rum, but never really mixed anything. Rum was my favorite of the three. Vodka was fucked, but it was cheap Vodka, so I can't really judge it based on that. What is a simple mixed drink I can make that I might enjoy?", "topk_rank": 6 }, { "id": "corpus-2296019", "score": 0.585583508014679, "text": "Howdy there DIY! \n\nBeen vaping for nearly a year now, was in need of juice and the next lot was gonna cost me 400 for 2 months worth of liquid, so i figured id give diy a small go. \n\n\nPicked up some VG and PG, 4 TFA concentrates. Did a small 20ml batch of strawberry/VBIC. Have yet to sample but smells delicious.\n\n\nMixing by volume atm, hunting for a decent scale I can grab if this all goes well. \n\n\nCleaning - currently dont have a Ultrasonic cleaner, rinse all my stuff RDAs etc in warm water. Is this fine to do for bottles and syringes? \n\n\nShould I use different syringes for PG and VG/Concentrates when mixing? \n\n\nAny pro tips on what you guys do would be greatly appreciated. \n\n\nMixing at 70 VG, 30 PG.\n\nEdit: Currently not mixing with Nic either, just small and simple.", "topk_rank": 7 }, { "id": "corpus-777526", "score": 0.585568904876709, "text": "I’ve heard this from various people across my life but can’t seem to believe it\n\nOunce for ounce, does clear liquor like gin, vodka, (some) tequila and rum really have less calories or sugar or so on than Whiskey,(some) rum and tequila, etc?", "topk_rank": 8 }, { "id": "corpus-2013206", "score": 0.585564911365509, "text": "If you’re drinking alcohol can you negate the damage done to your health by drinking more of a proportion of water in a single session? Like if you took a shot of alcohol and then drank a gallon of water would it be enough to not damage your liver? Or if you drank an entire bottle of vodka then drank multiple gallons of water could it negate the damage done by the vodka?", "topk_rank": 9 }, { "id": "corpus-2324970", "score": 0.585552453994751, "text": "I work for Starbucks, and I’m ashamed at how much waste we produce. I’ve been taking our morning newspapers home to compost/use, and I take boxes home to recycle/compost when I can. But I’m looking for ways to collect plastic (like straws who’s wrappers got soggy and cannot be given to a customer or lids that fall on the ground) and either reuse it for something or make something cool. Like weaving a basket out of the straws? Stuff like that. Ideas?\n\nMy store saves milk caps to donate to charities who recycle them for money, and I’m going to look into saving coffee grounds! We must through out hundreds of pounds of grounds a day, so if that can go back to the environment, it’d be a huge step for my store. I’d love advice for things like this as well!", "topk_rank": 10 }, { "id": "corpus-848878", "score": 0.5855520367622375, "text": "Is there some benefit to these I'm missing? I'm sure you know the kind - tervis clones with plastic lids that press into place and cost 25 dollars. They might be regular mug sized or big travel mugs. And they don't have any seal, just a plastic lid with a hole to drink out of. \n\nAm I doing something wrong by strangling my beverage with a locking vacuum seal? Because I really like not having to carry a mug upright when I'm trudging into work with my briefcase and lunch in the morning", "topk_rank": 11 }, { "id": "corpus-30940", "score": 0.5854536890983582, "text": "What makes vodka *vodka* is the decision to produce a distilled alcoholic beverage that has no added flavorings nor aged in vessels that might infuse it with flavors (such as whiskeys being aged in barrels that have been charred inside). I myself had long wanted to try a vodka made from potatoes--but since the point of making vodka is to produce a not-distinctly-flavored beverage (flavored vodkas notwithstanding), I don't imagine a potato-based vodka is going to be at all distinctive. And since vodka isn't supposed to have a strong flavor, it's one where I don't mind buying from the \"bottom shelf.\"", "topk_rank": 12 }, { "id": "corpus-37972", "score": 0.5854514837265015, "text": "One key reason is you lose alcohol from spirits aging in the barrel, especially in relatively dry, air conditioned homes. In production this is called the \"angel's share\". Most people don't want to buy an 80 proof liquor and drink perhaps 60 or 70 proof liquor. Further, many distilled spirits involve blends from several batches or barrels, to even the bottle to bottle and year to year product differences. Selling the spirit in a barrel would greatly increase the difference. Finally, cost of tiny barrels (barrels work by fitting wood strips together tightly enough to not significantly leak) is substantially higher than the cost of bottles. Even large barrels are fairly expensive.", "topk_rank": 13 }, { "id": "corpus-13238", "score": 0.5854007005691528, "text": "I believe its nucleation. The rough surface of the ice provides a huge surface area for bubbles to form on. The warm soda melts the outer edge of the ice, leaving it smooth and rapidly reducing the area for nucleation. So the fizz subsides fairly quickly.", "topk_rank": 14 }, { "id": "corpus-9125", "score": 0.5853764414787292, "text": "Long story short, it seems to be caused by different types of plastic being used due to government regulations. _URL_0_ _URL_1_", "topk_rank": 15 }, { "id": "corpus-160613", "score": 0.5853599309921265, "text": "It's a liquid. The stuff in the can is a liquid, but only because it's kept under a lot of pressure; as soon as it escapes, it turns to gas.", "topk_rank": 16 }, { "id": "corpus-1658392", "score": 0.5853295922279358, "text": "I know this may seem weird, but I can’t drink water out of anything that isn’t clear. Even if the bottle is see through but tinted a color. The problem is most clear water bottles that I have found are cheap plastic. I don’t mind pouring out some money on this one, and I have no one else to turn to. Help me Water N-wordas.", "topk_rank": 17 }, { "id": "corpus-264710", "score": 0.5853210091590881, "text": "It is called [Rheoscopic fluid](_URL_1_). They have found some sort of microscopic particle that is both rheoscopic and edible and thrown a handful of that in. [Here's another video of rheoscopic fluid in action.](_URL_2_) Edit: It is probably fine particles of [glycerol stearate](_URL_0_).", "topk_rank": 18 }, { "id": "corpus-1043605", "score": 0.5853026509284973, "text": "Going to play around with making a clarified milk punch as my pseudo-eggnog this year. I've made a few before but I've never tried to come up with my own spec. Right now I'm thinking of starting off with a base of brandy, spiced rum, and black tea. But for the acid to use...\n\nI'll experiment with various specs, but one thing that I've noticed is that an overwhelmingly large portion of specs call for pineapple juice instead of (or in addition to) other sources of acidity.\n\nI'm curious what I should expect (mostly flavor wise since I have citric and malic acid that I can add to my liking) when playing around with making my own. Thanks!", "topk_rank": 19 } ]

[ { "id": "corpus-325388", "score": 0.71694415807724, "text": "No, gravitational time dilation requires a gradient in the potential, i.e. you have to compare two clocks where one clock is much further down in the gravitational potential than the other clock. After the big bang, the Universe (and thus the potential) was extremely homogeneous. Why it expanded exponentially is still up to debate. It would solve a lot of problems if it did, that's why we believe it did. But the mechanics are not entirely understood yet. It might involve some scalar field tunneling from a false to a true vacuum state." } ]

[ { "id": "corpus-316353", "score": 0.6810872554779053, "text": "This isn't exactly correct. The energy density of the universe is decreasing with expansion, as a finite number of photons and baryons are occupying a constantly larger and larger space. What is believed by many cosmologists is that there is a separate source of energy dubbed a \"cosmological constant\" which is invariant with respect to the expansion of space. In other words, when you double the amount of space through expansion, you double the CC energy. The short answer to your question is that (assuming the CC interpretation is correct) we have no idea. Research in this area is quite new, since cosmic acceleration was first observed about 15 years ago. But it would have to be a fundamental property of space.", "topk_rank": 0 }, { "id": "corpus-136312", "score": 0.6810854077339172, "text": "We are, but as soon as we start to expand, electromagnetism pulls our molecules back closer together again. The expansion of the universe is so miniscule on smaller scales (and \"smaller scales\" in this case even includes local galaxy groups) that every other force completely overwhelms it. (Even at galactic scales, gravity can overwhelm the expansion of the universe and keep groups of galaxies gravitationally bound to one another)", "topk_rank": 1 }, { "id": "corpus-254237", "score": 0.6810572147369385, "text": "Of course there is no absolute notion of who is stationary and who is moving, that's what \"relativity\" means. The point is that if you have two observers moving relative to each other then each will see time move slower for the other. This is also what leads, naively, to the [twin paradox](_URL_0_).", "topk_rank": 2 }, { "id": "corpus-304993", "score": 0.6810467839241028, "text": "In a vacuum, things can accelerate until arbitrarily close to the speed of light as long as a force is being applied (relative to some initial rest frame). However, space contains very sparse amounts of interstellar gas, and at high enough speeds the [blueshifting of the cosmic backgroun radiation](_URL_0_) can apply enough radiation pressure to limit the speed very slightly below that of light.", "topk_rank": 3 }, { "id": "corpus-265302", "score": 0.6810189485549927, "text": "\"Weak force\" is a bit misleading anyway. It rarely has effects that look like a classical force. \"Weak interaction\" is a better term. The large mass means it does not have a long range and (combined with the short lifetime of the bosons) no radiation, these would be necessary to assign a meaningful speed value to it.", "topk_rank": 4 }, { "id": "corpus-61306", "score": 0.6809978485107422, "text": "This really depends on your point if view. A separate observer at rest to the rest of the universe would see the distance between them growing at almost 2x light speed (almost because they can't ever quite reach light speed). But each of the travelers would only see the distance growing at just under light speed.", "topk_rank": 5 }, { "id": "corpus-297968", "score": 0.6809945106506348, "text": "Note: the information is the just the *amount you learned after the event happened*. Information is a feature of a description (specifically a probability distribution), not reality. It's not synonymous with matter or energy or any physical quantity. Saying the information *would* be infinite gives no explanation for how of why it happened in the first place, which is the entire problem of interest. It's trivial to come up with tons of low probability/impossible statements in your head right now, but they're not *doing* anything to the universe.", "topk_rank": 6 }, { "id": "corpus-266061", "score": 0.6809929609298706, "text": "Your cells are all subject to the laws of physics, so they also age slower. The passage of time itself physically slows down, it's not a matter of perception.", "topk_rank": 7 }, { "id": "corpus-304163", "score": 0.6809830665588379, "text": "I'm going to assume a lot of things, but for the most part we shouldn't experience the lag. The big assumption is that our simulation is made up of frames - that what we perceive to be fluid time actually can be broken down into quantized stills - this is not too dissimilar from the concept of Planck-time. This would also mean that if we're part of this simulation, the *time in between frames* would be totally irrelevant to us, because that \"lag\" is entirely outside of our concept of time or reality. In a similar way, there's no way for you to tell if time had suddenly frozen for an hour before resuming - for you it would have just been continuous.", "topk_rank": 8 }, { "id": "corpus-38877", "score": 0.6809737682342529, "text": "The motion is microscopic, and there are forces which dominate at the scales of objects such as you and I. That said, it's only true because we're relatively big and slow; everything has a wavelength described by the de Broglie relation: Lambda = Hbar/p where Lambda is the wavelength, Hbar is the Planck constant, and p is momentum. That is to say, if it has enough momentum, matter acts like a wave. Fortunately for us, we don't exist in a scale at which those effects become apparent, and forces such as electromagnetism dominate.", "topk_rank": 9 }, { "id": "corpus-260857", "score": 0.680957019329071, "text": "I didn't read all of Midtek's response, so apologies if this is redundant, but I will summarise why light seems special. Actually light is NOT special. In the context you are talking about, it is *mass* which deserves to be called special. Without going into details, there is a relationship between mass, momentum, and energy in Einsteinian relativity. This goes some way towards describing kinematics in spacetime. The effects which you mention -- length contraction and time dilation -- are actually related to this, and not necessarily anything to do with light. The relevant part for your question is what happens when the mass of a particle is set to zero -- we find that it is now constrained to a single constant speed in all reference frames. Again, completely general for massless particles, nothing to do with light in particular. Light only seems special because it is (or rather photons are) an example of a massless particle.", "topk_rank": 10 }, { "id": "corpus-281078", "score": 0.6809467077255249, "text": "Photons do not have a valid reference frame and thus can not experience anything. If you ignore the reference frame part, you *could* say that they experience maximum time dilation where time stops completely. I would be careful with that statement though.", "topk_rank": 11 }, { "id": "corpus-250358", "score": 0.6809190511703491, "text": "At a point when everything in the universe is at absolute zero it does NOT mean that everything is standing still. Due to the Heisenberg uncertainty principle, this simply cannot happen. A better way to thjnk of it is that at absolute Zero we reach a point of minimum movement. Particles would be undergoing small oscillations", "topk_rank": 12 }, { "id": "corpus-835462", "score": 0.6809107065200806, "text": "I love physics and I've been getting started on it by reading different books and papers on several issues. Today I found myself questioned by an enigma that I could not answer, since I have not yet read (or understood) the rules and basics of the theory: the theory of relativity.\nAccording to what I understand, such theory states that the faster you move the slower u \"experience\" (?) time. Is that the reason why while moving at amazing speeds (the earth itself, or the earth travelling around the sun and with it) we feel like time is going slow? Or does that only apply to other observers? Also, is that why we don't feel dizzy or get \"kicked off\" the earth? And I know we are \"pulled\" down by gravity, but the earth's rotation speed is huge, why are we not sent flying away? (Sorry if the question sounded juvenile or childish). Also, sorry for any grammar or redaction mistakes, I'm not a native speaker.", "topk_rank": 13 }, { "id": "corpus-273121", "score": 0.6808953285217285, "text": "That's roughly the cosmic event horizon: the point where the expansion of the universe passes the speed of light, so a photon emitted from 15 billion light years away will never reach Earth. It's not connected to the age of the universe (even though it is oddly close to it), but rather, it's the Hubble constant divided by the speed of light.", "topk_rank": 14 }, { "id": "corpus-833867", "score": 0.6808937191963196, "text": "As I’ve heard, there is an inverse square law that changes the time as distance changes - but I don’t quite understand that. \n\nAny assistance would be great. Thank you 🙏\n#physics", "topk_rank": 15 }, { "id": "corpus-2326364", "score": 0.6808745861053467, "text": "I have a few questions regarding astrophysics after I've more or less run out of documentaries and lectures. :)\n\n1: Why didn't the big bang cause a black hole?\n\n2: I really dislike the concept of \"infinite\", and have a hard time understanding why the gravitational pull of a black hole does not affect the entire universe. Is the singularity has infinite in it's equation, then shouldn't this be the case? Also, how can there be different sized black holes since gravity is already infinite?\n\n3: Can dark energy have something to do with black holes?\n\n4: Since the big bang started at a point, shouldn't the universe has a center we could find by variations in redshift?\n\nLastly, where does the information/hawking radiation go?", "topk_rank": 16 }, { "id": "corpus-318577", "score": 0.6808742880821228, "text": "> would it be cylindrical and would bend back in on itself at the edges if we ever found the theoretical \"edge\". Think of it as going to the top edge of a map in a video game and ending up at the bottom edge. No, that would be roughly what happens in a *finite* universe (well, provided it's either not subject to accelerating expansion or you left early enough in the lifetime of the universe). No edge; just wrapping back around on itself. More like the surface of a sphere than a cylinder, though. In an infinite universe, you just keep going. Forever.", "topk_rank": 17 }, { "id": "corpus-317237", "score": 0.6808691024780273, "text": "\"Infinite energy\" isn't the best way to look at it, because infinite energy doesn't really mean anything, especially not to people. What they mean by that is that the kinetic energy required for an object with mass m to travel at a velocity v is equal to mc^2 (1/sqrt(1-v^2 /c^2 )-1), and that goes to infinity as v approaches c. A better way is to think about the time it would take to accelerate an object to the speed of light under a constant acceleration. The velocity relative to c as a function of time is the hyperbolic tangent of the acceleration times time. The velocity will never reach c in finite time.", "topk_rank": 18 }, { "id": "corpus-288063", "score": 0.6808618903160095, "text": "Good question, but such a theory would be incorrect, for several reasons. First, the universe is expanding at an accelerating rate. This means that galaxies are generally moving away from us, and galaxies that are sufficiently far away are moving away from us faster than the speed of light. (Though their motion through local space is always less than *c*.) Second, if we ignore universal expansion, not all mechanical systems are gravitationally bound. The escape energy/velocity is obtained by integrating the gravitational force between two bodies until their distance is brought to infinity; because gravity scales as 1/r\\^2, this energy is finite. For example, the sun has an escape velocity of about 43km/s, so anything traveling away from the sun faster than this speed will slow down over time due to gravity, but only to a finite (non-zero) speed, and will continue to travel away from the sun at that final speed forever.", "topk_rank": 19 } ]

[ { "id": "corpus-325389", "score": 0.7383737564086914, "text": "There is as yet no evidence for planets having moons anywhere outside the Solar System, much less moons around moons. Measurements are just now getting [sensitive enough](_URL_0_) that the detection of moons outside our the Solar System should be possible. As for the challenge of a moon having a moon, take a look at [this](_URL_2_) or [this](_URL_1_). Bottom line, it's not logically impossible, but having a stable configuration would be unlikely." } ]

[ { "id": "corpus-296917", "score": 0.7001670002937317, "text": "In terms of natural satellites, yes. The moon and earth share this relationship. It's called 'tidal locking'.", "topk_rank": 0 }, { "id": "corpus-321725", "score": 0.7001532316207886, "text": "Yes! Rhea, one of Saturn's moons, most likely (EDIT: *might*) does have rings. [The moons of Rhea on Wikipedia](_URL_0_) Every stellar body has what's called a \"Hill sphere,\" which is a region around it where it dominates the gravity field, rather than something bigger. So, the Moon fits within Earth's Hill Sphere (instead of the Sun's) and Rhea fits within Saturn's, and so on. So since every moon has its own Hill Sphere, there IS a region of space in which a moon is the dominant gravitational body, rather than the parent planet. Gravity depends on only two things: Mass, and distance from the center point of that mass. So one problem with Hill spheres is that for a lightweight but voluminous moon close to a large planetary body, the Hill sphere might be inside that moon's own radius. Earth is outside the Moon's Hill sphere, so it's possible that the moon could one day have its own satellites or rings.", "topk_rank": 1 }, { "id": "corpus-297877", "score": 0.6993625164031982, "text": "Depending on how you define satellites, Saturn could have millions. If you want spherical ones, then yes there is. Moons cannot exist below the roche limit, nor can they exist above the hill sphere, nor can they be too close together. As such, there isn't a hard limit, but there is a limit dependant on the characteristics of the planet. If not, then yes there is too. Too high a density of tiny moons (asteroid sized) would cause them to eventually coalesce, reducing the number of moons.", "topk_rank": 2 }, { "id": "corpus-302639", "score": 0.6991912722587585, "text": "Almost by inspection, moons. Our own solar system has hundreds, possibly thousands of moons (depending on how you count). And since there's on average about one planet per star, and an average of several moons per planet (at least in our solar system), and the potential for smaller bodies like asteroids or free floating planets to have moons, it's a good guess that there are significantly more moons than stars. Of course, until we get some solid confirmations of exomoons and begin to understand the population, this is just conjecture. But the huge preponderance of moons in our own system makes it a decent bet that there will be several moons per star at the least.", "topk_rank": 3 }, { "id": "corpus-317611", "score": 0.698431670665741, "text": "Yes, [approximately half](_URL_0_) of the moons in our solar system are tidally locked to their parent planet, meaning they only ever show one side to that planet.", "topk_rank": 4 }, { "id": "corpus-283707", "score": 0.6981041431427002, "text": "If you were in a galaxy, I'd have to say yes. If outside a galaxy, probably not. I say this because even during a new moon, the light from our galaxy itself is capable of casting a very light shadow. You would need to be far away from any light pollution to see this.", "topk_rank": 5 }, { "id": "corpus-318435", "score": 0.6969397068023682, "text": "These types of systems are known as S-type planets, and there are many, many examples of these already discovered. We don't have any examples of moons yet, but the addition of the extra binary star wouldn't really affect a planet's ability to have moons except in pretty extreme cases. Some work has been done on these types of planets and their habitability too, see e.g. [Quintana & Lissauer \\(2007\\)](_URL_1_) or [Cuntz \\(2013\\)](_URL_0_).", "topk_rank": 6 }, { "id": "corpus-318419", "score": 0.6967214345932007, "text": "There are moons a lot bigger than ours, and moons so small they're just big boulders. There are moons made of rocks, and moons made of ice. There are moons exposed to the vacuum of space, and moons with a thick atmosphere, clouds, and rain. (Well, one anyway.) There are moons that are almost perfectly smooth, and moons with cliffs 20 kilometers high. There are moons covered with huge active volcanoes, and moons that have been inert for billions of years. There are moons with liquid water ocean inside, and moons that are solid to the core. There are white moons and black ones, yellow, orange, and grey....", "topk_rank": 7 }, { "id": "corpus-244045", "score": 0.6963656544685364, "text": "Few months ago an article was submitted to /r/science that describes the latest model made by planetary scientists. Under this model both Earth and Mars suffered giant impacts that created the moons, but Earth used to spin much faster than Mars, so tidal effects boosted our Moon to a higher orbit while Phobos stayed in a relatively low one. Furthermore, a larger moon is supposed to have formed on Mars but already crashed before we had a chance to exist and observe it - its gravitational influence would explain the almost perfectly circular and equatorial orbits of Phobos and Deimos. Everything is to be taken with a grain of salt because this is recent research. We need more studies before it becomes a widely accepted theory (if it does). I'll try to find it and link it. Edit: couldn't find the /r/science submission but the article is here: _URL_0_", "topk_rank": 8 }, { "id": "corpus-265441", "score": 0.6960293054580688, "text": "Yes! There are intergalactic stars, not bound to any galaxy. Most likely they formed in a galaxy and got ejected, either when two galaxies collided or by gravity assist from a large object like a supermassive black hole. There are probably other intergalactic objects too, but if they don't give off their own light we'll probably never find them. _URL_0_", "topk_rank": 9 }, { "id": "corpus-581598", "score": 0.69371098279953, "text": "If so, how long until the event completes, and how many moons would there be?", "topk_rank": 10 }, { "id": "corpus-310556", "score": 0.6935182809829712, "text": "I don't think I saw this covered, but these were found by the planets passing in front of the star. RV (wobble) would just give us a minimum mass, and wouldn't be able to distinguish between a double planet and a single more massive planet. Transits would be able to, and [here's](_URL_1_) some simulations from Kipping et al (hosted by universetoday) that show what it'd look like with a very large moon. You'll be able to see that sometimes there's two dips, and sometimes the planet and moon are both transiting at the same time, so the transits are overlaid. Re the game: ignore the tutor on that, and if you need assistance on population statistics for that system generation, let me know if you need particular sorts of data", "topk_rank": 11 }, { "id": "corpus-301885", "score": 0.6933404207229614, "text": "You got it backwards. Moons can become rings if they are inside the [roche limit](_URL_0_). Rings don't turn into moons.", "topk_rank": 12 }, { "id": "corpus-313337", "score": 0.6927149891853333, "text": "Most of the time we don't have the tools to find something. We don't have a clear confirmation of anything orbiting exoplanets. There is a very strong indication that [this planet](_URL_1_) has rings and [Kepler-1625 b](_URL_2_) probably has a moon, but that's it. * We haven't found any trojans (orbiting 60 degree ahead/behind of a planet) outside the solar system. * We haven't found co-orbital planets similar to the moons [Janus](_URL_0_) / [Epimetheus](_URL_3_) around Saturn. * We haven't found \"rings\" of several planets sharing the same orbit. Theoretically stable if there are enough planets but I'm not aware of plausible formation mechanisms. * As far as I know we don't know any system where different planets orbit in completely different planes.", "topk_rank": 13 }, { "id": "corpus-320930", "score": 0.6918777227401733, "text": "Yes. The difference to a planet and moon system is not a sharp dividing line, however. We know from exoplanet observations (mainly transits) that these systems have to be rare close to the stars, but they could be more common for larger separations.", "topk_rank": 14 }, { "id": "corpus-305510", "score": 0.691649317741394, "text": "The closest example I can think of are the [co-orbiting satellites of saturn](_URL_0_). They technically orbit each other though that orbital period is longer than thir orbital periods around Saturn. I am sure that some natural objects orbit many of the moons in the solar system, but they would be small and hard to spot.", "topk_rank": 15 }, { "id": "corpus-534739", "score": 0.6912685632705688, "text": "i know this is a simple question and probably stupid to most but on the desktop i cant seem to find anything about moons in the subbreddit nor my profile page. could anyone help me out on this if the mods dont mind?", "topk_rank": 16 }, { "id": "corpus-301372", "score": 0.6895131468772888, "text": "There are plenty of \"rogue\" stars that are extragalactic! As for a solar system outside of a parent galaxy, it's possible - though we've yet to observe any for obvious reasons (our scope of view is limited to the Milky Way for any practical planetary observations).", "topk_rank": 17 }, { "id": "corpus-317297", "score": 0.6891196966171265, "text": "To reiterate what Weed_O_Whirler said, most of the inner planets don't have moons because their gravity wells are so small. The formation of the Moon as explained by [giant impact hypothesis](_URL_0_) probably was a pretty unusual event: instead of a Mars-sized planetesimal being gravitationally pulled in by one of the gas giants, it was grabbed by the early Earth. So really the bigger question is: **Why does the Earth have any moons at all?**", "topk_rank": 18 }, { "id": "corpus-296722", "score": 0.6890356540679932, "text": "Yes, this has been found, but presently it's thought that stars only form inside galaxies, so these star systems are thought to have been thrown out of galaxies due to galaxy collisions. One example is the star HIP 13044 and its planet, [HIP 13044b](_URL_0_), which was found in a stream of vagrant stars that loop around the Milky Way. Astronomers think this stellar stream is all that remains of a dwarf galaxy that once orbited the Milky Way.", "topk_rank": 19 } ]

[ { "id": "corpus-325390", "score": 0.7157502174377441, "text": "We don't know! There was a [paper in Science](_URL_3_) just this year on some of the newest results. It used to be that everyone thought it was the gyroscopic stability from the spinning wheels. But then somebody constructed a bike that had counter-spinning wheels to negate that, and it turned out it could be ridden anyway. It's not likely to be any single thing. But it's a (somewhat) active area of research, actually." } ]

[ { "id": "corpus-156835", "score": 0.6799337863922119, "text": "There's a tiny motor inside it with a weight. The weight is offbalanced. So when the motor spins, the weight is slung from side to side. [Here](_URL_0_)", "topk_rank": 0 }, { "id": "corpus-100168", "score": 0.6798778176307678, "text": "TLDR; It allows them to fine tune their balancing needs. Longer pole allows more subtle changes to their balance.", "topk_rank": 1 }, { "id": "corpus-161614", "score": 0.6796861886978149, "text": "Pavement is much smoother than grass. Textured surfaces have more friction that make it harder to pedal a bike against. Also, yards aren't as hard as pavement so your bike tire can sink a little bit into the grass under your weight, creating even more texture & friction to fight against when pedaling, plus if your wheels sink in then you're not only fighting the texture but also fighting gravity as you pedal your way up out of the groove.", "topk_rank": 2 }, { "id": "corpus-124090", "score": 0.6796155571937561, "text": "Wheels reduce friction. if that same 500lbs block was on ice ( with a layer of water in between) you would be able to move it as easily or even easier than on a wheel ( because there is still friction, just a lot less)", "topk_rank": 3 }, { "id": "corpus-934729", "score": 0.6792615652084351, "text": "I recently got a single speed road bike for riding around my city. I'm not very experienced at this sort of riding, and I'm finding the drop bars that are currently on it to be less than ideal. They're so low that I have a find I have to reposition myself more upright if I intend to signal a turn, and the low riding position makes it hard to turn my head to see what's around me. \n\nIs there a better option? Maybe bullhorns? Something else?", "topk_rank": 4 }, { "id": "corpus-935370", "score": 0.6790737509727478, "text": "The first time riding the bike the handlebars felt super loose and responsive which made me feel like I could lose balance at any moment. Is this normal?\n\nThe first thing I did while riding was try to figure out what foot I ride forward. I thought it would be my right but it seems I default to left forward after pedaling. Is this a good indicator I’m left foot forward?", "topk_rank": 5 }, { "id": "corpus-95054", "score": 0.6789820790290833, "text": "It puts more weight on that side, causing it to have more friction, and slowing down that side. This makes you turn in that direction.", "topk_rank": 6 }, { "id": "corpus-51593", "score": 0.6789250373840332, "text": "Stability is mainly affected by two things: centre of mass, and base area. When standing you have a higher centre of mass, and a smaller base area (only your feet are in contact with the floor as opposed to your butt), so you are less stable than when sitting. The same forces act upon you when standing or sitting but they toss you around more when standing.", "topk_rank": 7 }, { "id": "corpus-2296469", "score": 0.6788669228553772, "text": "I'm currently in the process of learning to ride a unicycle (20 inch). I've read all the advice and watched countless videos both before getting the unicycle and during my resting periods. So far, my farthest run is about 10 feet and most of my attempts are 1-1.5 revolutions. \n\nOne thing I see a lot is to get away from a wall to assist as soon as possible. For working on balance this is obviously true. However, in my experience there are things other than balance that I really need to work on for success. The first thing is weight distribution. By that I mean putting my weight in the seat rather than the pedals. Second is the mechanical motion of pedaling. I often didn't commit to pedaling fast which resulted in falling immediately. \n\nRiding with the wall allowed me to spend a lot of time learning those things when I otherwise wouldn't be able to. Working on balance is extremely difficult for me when I'm not commiting to moving forward and I'm basically standing by putting my weight on my feet. For these reasons, I recommend putting extra time with that assist as long as you're focusing on improving something specific. \n\nIt may be worth noting that I spent time alternating back an forth with assist and without. I'm trying to avoid creating a habit of using the assist, but still gain the skill improvement that I can by using it. I'm at the point now that I don't use the wall to assist, but I did use it way more than people seem to recommend. \n\nWhat do you guys think? I'm still only 2 days in so I cannot be considered an expert.", "topk_rank": 8 }, { "id": "corpus-191636", "score": 0.6787106990814209, "text": "We use many inputs to stay \"balanced\" - our inner ear, our muscles, our sense of inertia and ... our sight. You develop a _skill_ of staying balance using all of these inputs so it becomes natural that taking one away makes it harder to stay balanced. Had you learned to balance with your eyes close you'd be better able to maintain balance without sight.", "topk_rank": 9 }, { "id": "corpus-96001", "score": 0.6786178350448608, "text": "Too much cushioning would make it even more difficult to balance. Try doing yoga on your bed. The mat is there to help provide traction, and just enough cushioning to project your joints in certain poses.", "topk_rank": 10 }, { "id": "corpus-941745", "score": 0.6785774230957031, "text": "I recently started my first practical lesson, bike was cb190r. Not used to balancing 140kg while keeping the clutch at biting point. Any tips on how to balance better? Also how do you not jerk the bike when throttling?", "topk_rank": 11 }, { "id": "corpus-2791141", "score": 0.6785723567008972, "text": "I just learned about changing the suspension block so you can fold the bike w/out pressing the lever...\n\nI rarely carry my bike unfolded so it seems like a smoother step. Are there any concerns as far as the ride? I lift out of my saddle for some bumpy rail tracks otherwise can't see any times short of being launched airborne where the bike would fold up on me?", "topk_rank": 12 }, { "id": "corpus-291458", "score": 0.6784847974777222, "text": "If the problem is reduced to the ideal case - no air resistance, weightless bikes with frictionless drivetrains, inflexible wheels with no slippage, then yes, the heavier rider will have done twice the work. You can see in all the other answers that there are a lot of other factors (air resistance, bike weight, tire flex, etc.) that can be added to the equation to get a more precise answer.", "topk_rank": 13 }, { "id": "corpus-186481", "score": 0.6783846616744995, "text": "Imagine being on your bicycle in a giant concrete bowl. Try to ride out by going straight up one side. Your body and bicycle would be ill-designed (including heavier) to provide the burst of power needed to go that way. Next, imagine riding in an ever-growing circular path. It may take several rotations, but you'll expend less energy that way in the long run. There would certainly be less need to hit the gym for years in preparation.", "topk_rank": 14 }, { "id": "corpus-127236", "score": 0.6781770586967468, "text": "It's due to steering being controlled by the front wheels. Once you have the back of the vehicle in place, the front wheels allow you to maneuver the front with more precision. If you try to pull in forward, you easily get the front in place, but there's no easy way to swivel the rear of the vehicle into place.", "topk_rank": 15 }, { "id": "corpus-934837", "score": 0.6779144406318665, "text": "Update: Wow, thanks for all the great feedback everyone. I am really looking forward to my bike, and it seems like a lot of the time when the bike goes down, it could be prevented either by riding within your skill, or being a bit more prepared. Thanks! \n\n\nFor the past year and a bit I have been lurking this before signing up, and I have noticed that the biggest worry I have when I do get my first bike is the notion of *it will be dropped* in some form or another. \n\nI am curious now to know is of those of you who have dropped/lowside/highsided etc your bike, how much of it was preventable. Did you go out in bad conditions, target fixation, too fast, too slow, etc. Vs how many have gone down because another motorist put you in a position where a collision would happen had you not gone down. \n\nAlso is it more common for particular styles of bikes to go down, do cruisers go down less?\n\nPlease share your story of when your bike went shiny side down, and how you think you could have prevented it.", "topk_rank": 16 }, { "id": "corpus-118353", "score": 0.6778197288513184, "text": "Both the gyroscopic effect and the caster effect have been simultaneously cancelled out in experiments of riderless bikes and the bikes are still stable. [Popular Mechanics article.](_URL_1_) (Too much?) [An askscience submission with good replies.](_URL_0_) Maybe someone can put [camber thrust](_URL_2_) in ELI5 terms.", "topk_rank": 17 }, { "id": "corpus-2021011", "score": 0.6777949929237366, "text": "I mean on flat ground. Say if you were to bike really fast and then only hit your front brakes? Could you do a full front flip and keep riding? I don't know much about the physics of it, but I made an unsuccessful attempt when I was 12 and have been wondering ever since.", "topk_rank": 18 }, { "id": "corpus-51884", "score": 0.6777938008308411, "text": "You allow the seat to absorb more of the impact. This prevents more serious injuries such as spinal injuries and holding onto your ankles or seat in front reduces the risk of broken arms etc Source: Mythbusters did an episode about it", "topk_rank": 19 } ]

[ { "id": "corpus-325391", "score": 0.7430144548416138, "text": "The skin contains 2 different sections that are called the epidermis and dermis. The epidermis is the outer section (closer to the surface) and the dermis sits below it. The layer of the epidermis which is in contact with the dermis is called the basal layer, this is the layer important to fingerprint formation. Before the fingerprints form the cells in the basal layer all sit in a straight line. For reasons that aren’t exactly clear, around the 10th-16th week of pregnancy the cells of this layer begin to become undulated (take on a wavy arrangement instead of a straight line). As time progresses this will change the arrangement of the layers of the epidermis above it. Eventually these undulations appear on the surface of the epidermis too where they are seen as fingerprints. This is also the reason that superficial skin injuries do not destroy your fingerprints. They are caused by something that is deep underneath the skin so damage to the surface doesn’t prevent them from re-forming when the skin heals." } ]

[ { "id": "corpus-321108", "score": 0.704713761806488, "text": "No. Fingerprints are determined by the motion of fluids in the uterus during gestation. This is why identical twins (exact same DNA) do not have identical fingerprints.", "topk_rank": 0 }, { "id": "corpus-186422", "score": 0.7045764923095703, "text": "Grip. They help with grip. Also, when your fingers get wet and go all puffy and the finger prints become engorged, that's NOT because they absorbed water. We have blood vessels that expand to make them go like that when we are in water. Again though, for grip.", "topk_rank": 1 }, { "id": "corpus-130160", "score": 0.7042641639709473, "text": "Yes. There are cases of criminals utilizing burning or grafting to alter their fingerprints. Gruesome process, really. Made me cringe as I typed this out.", "topk_rank": 2 }, { "id": "corpus-242572", "score": 0.7035471796989441, "text": "You're right about the \"unseen blueprint\", only those are better known as genes. Every cell in a human's body contains the the same set of genes, but not every gene is expressed in all the cells. Gene expression depends on various factors like the functions of the cell, the location, etc. For example, the beta cells in your pancreas express genes which produce insulin, whereas the parietal cells in your stomach don't; they produce acid instead. When there's damage to tissue, the damaged tissues release chemical mediators which promote inflammation, which leads to repair. Here, the stem cells in the skin get activated and they multiply and express the specific genes. Each cell produces proportionate amounts of keratin. This leads to preservation of the fingerprints. But, if the injury was deep enough to completely destroy the stem cells, the fingerprint would be lost and would be replaced by scar tissue.", "topk_rank": 3 }, { "id": "corpus-320878", "score": 0.7035459876060486, "text": "The cells that make up your freckles/birthmarks split into basically identical copies of themselves through a process called Mitosis and since they do not move, the new daughter cells have the same pigment of the parent cell and take their place after the cell dies. Basically, the new cells inherit the parent cell's position. If you have any other questions on this or clarification I would be happy to help!", "topk_rank": 4 }, { "id": "corpus-24300", "score": 0.7031112909317017, "text": "When skin is met with direct ongoing pressure (pain, damage, etc), it starts to basically make more skin on the top layer to protect the inner layers. It doesn't happen overnight, but they can form rather quickly. The proof is in how at first your fingertips hurt but the next day it wasn't that bad. Your skin created a tougher layer of skin on the areas it was hurt (your fingertips) to protect it from any future damage that could happen.", "topk_rank": 5 }, { "id": "corpus-133211", "score": 0.7029725909233093, "text": "Finger prints are thought to be useful for adding friction. I.E. it helps you grab things easier.", "topk_rank": 6 }, { "id": "corpus-4483", "score": 0.7008693814277649, "text": "It's 11pm and I'm on my second glass of wine, so I can't be bothered to do the math. There are three types of fingerprints: whorl, loop and arch. Most people have 10 fingers, and can have any combination of those three fingerprints. There are also three different ways you can take a fingerprint: flat, slap or roll. Each method carries its own number of exact or \"sort of, pretty close\" matches. There's [a paper/presentation by Michigan State](_URL_0_) that discusses the probability of fingerprint configuration, and each source in the table has a number to the power of at least 11, which far exceeds the world's population estimate of about 7 billion. But it's sort of like lottery numbers. The odds may be incredibly small that you draw the winning ones, but that doesn't necessarily exclude other people from having the exact same combination as you. So it's possible, just not very likely.", "topk_rank": 7 }, { "id": "corpus-278706", "score": 0.7002922296524048, "text": "While it is theoretically possible that two people have the same set of fingerprints, it's not very probable. Fingerprints are formed in the womb and are influenced by a number of factors, such as fetal movement, flow of amniotic fluid around the fetus, and even the density of the fluid. These random factors all make it very unlikely that two people would be born with identical fingerprints. Even identical twins have different fingerprints.", "topk_rank": 8 }, { "id": "corpus-281281", "score": 0.7002420425415039, "text": "Depends on the extent of the damage - more specifically, if your injury is severe enough to disrupt the basal layer of your epidermis, your fingerprint would be affected. The friction ridges that define your fingerprint also exist in the junction between your dermis and your epidermis (as dermal papillae), and if your injury goes _that_ deep, it's possible to alter your print. This is also what allows some prints to be taken from a cadaver, even if the epidermis is damaged. You just peel the skin off like a glove, and both the underside of the epidermis and the dermis will contain the ridge structures.", "topk_rank": 9 }, { "id": "corpus-158481", "score": 0.7000808119773865, "text": "Not an expert, but if I recall correctly the home button (on an iPhone, at least) has something like a camera underneath that is actually taking pictures of your fingerprint.", "topk_rank": 10 }, { "id": "corpus-253493", "score": 0.6995221972465515, "text": "Via [spectroscopy](_URL_0_). Molecules absorb very specific wavelengths of light, thereby leaving a \"fingerprint\" in the form of an absorption spectrum.", "topk_rank": 11 }, { "id": "corpus-285646", "score": 0.698957085609436, "text": "It's been a few years since my forensic training so bear with me. The variance between fingerprints appears on a fetus during the second and third month of pregnancy. The exact cause is still up for debate but the most prevalent theory is the movement of embryotic fluid affects how the skin cells in your hands and feet align. An interesting note is that fingerprint shape is completely unaffected by your DNA. For example monozygotic twins will still have different fingerprints.", "topk_rank": 12 }, { "id": "corpus-162525", "score": 0.6989210844039917, "text": "I think OP is talking about the nail bed. The cuticles are the \"skin\" joined from finger to nail. Are you talking about the white semi-circles that are still part of you nail OP?", "topk_rank": 13 }, { "id": "corpus-73736", "score": 0.6982730031013489, "text": "My theory is they don't. They seam the colour they are because they are in contact with with your finger", "topk_rank": 14 }, { "id": "corpus-8156", "score": 0.6976619958877563, "text": "There's different ways a computer can do image comparison. One way is basically break down a fingerprint onto something like [grid paper](_URL_1_) with x,y positions. Then my fingerprint will say something like: Black at (4,5), Black at (4,6), White at (4,7), Black at (4,8) etc. hundreds or thousands of times. Like [this](_URL_0_). Then you can compare all these grid co-ordinates to another fingerprint. If say 99% of the squares are filled the same (Black or White) that's a good match. This is obviously a lot of work, but computers are great at doing millions of simple fixed logical comparisons in a very fast time. There's other ways to tackle this. There's also surrounding problems programmers need to solve too, like \"centering\" images so that they aren't off by one, how do you handle a fingerprint that's \"bolder with thicker lines\", etc.", "topk_rank": 15 }, { "id": "corpus-276080", "score": 0.6975986361503601, "text": "The simplest ones literally use a camera (usually infrared) to take a picture of your finger. Next, some basic image processing is used to convert the image into a normalized binary raster (i.e., thresholding is applied). Then, an algorithm selects identifying characteristics called \"minutiae\" from the raster. These minutiae are classified into a few categories (e.g., \"ridge stop\", \"ridge fork\"). The locations and types of the minutiae on the fingerprint essentially become a multi-dimensional vector, and similarity metrics can be applied between the collected vector and a database of known fingerprints. If a similar enough collection of minutiae is found, it is treated as a match. Reference: Mark Stamp. \"Information Security.\" 2nd ed., p. 244-245.", "topk_rank": 16 }, { "id": "corpus-154467", "score": 0.6972182393074036, "text": "A fingerprint is just a pattern, that happens to be found on your fingers, and any two individuals are very unlikely to share the same fingerprints. So what is stored in the database is a \"picture\" of the fingerprint. Computers are really good at pattern matching, and due to the speed at which they can perform calculations the new image can be compared to all images stored in the database one by one and if the same pattern is found in the sample and the one in the database it is flagged as a possible match.", "topk_rank": 17 }, { "id": "corpus-148073", "score": 0.6968421339988708, "text": "If you only damage the top layer of the skin, the epidermis, the underlying dermis contains the information to regrow the fingerprints in the same way. If you damage the dermis, you can cause scarring that prevents the fingerprint from growing back in the same way.", "topk_rank": 18 }, { "id": "corpus-106", "score": 0.6967990398406982, "text": "The idea that everyone has a unique fingerprint isnt really scientifically proven. There is a real possibility that you and someone else currently living have identical fingerprints.", "topk_rank": 19 } ]

[ { "id": "corpus-325393", "score": 0.7712842226028442, "text": "No. Or at least there are some elements that we cannot possibly detect even if they were produced in stars. There are some elements which have extremely short half-lives. Which means that they can be created in laboratories, and there's a very short time within which these can be detected before they decay into other elements. That means that even if they are made within stars or through chance chemical reactions, we wouldn't be able to detect them ( considering the distance and the very short time period they would exist) Earlier all transuranic elements were thought to be like this, so that they could only be produced synthetically. But now we know that there are those that exist naturally as well (like Plutonium). Those with atomic numbers above 99 have only been created in laboratories and have not been generated in stars. I think also Technetium (Tc 43) is not present in nature, but not sure about that one." } ]

[ { "id": "corpus-22266", "score": 0.7325399518013, "text": "The early universe was composed mostly if not completely of hydrogen. So the oldest stars will be almost completely made up of hydrogen. As stars go through their nova and supernova phases, they create heavier and heavier elements which are incorporated into the next generation of stars. You will obtain a larger spectrum of elements in younger stars and far fewer in older stars.", "topk_rank": 0 }, { "id": "corpus-320054", "score": 0.7325171828269958, "text": "While the largest stars are only able to form Iron in their natural process, occasionally stars run out of \"fuel\" and collapse in on themselves due to their immense gravity and cause an explosion called a supernova. During the supernova, a large amount of energy is released spurring a process known as nucleosynthesis which is what creates the heavier elements.", "topk_rank": 1 }, { "id": "corpus-170957", "score": 0.7317516803741455, "text": "So you start out with the birth of the universe, and the apparent production of a few light elements during the events of the big bang. Most of this is hydrogen. Some helium and lithium. These exist as nebulous clouds that collapse into stars, where stellar nucleosynthesis occurs, producing other elements. Some of these stars die explosive deaths, seeding the space around them with their contents, including bits of heavy elements, although the majority of matter in the universe is still hydrogen. More of these clouds, now sometimes seeded with heavier elements collapse into rotating discs. The center of these can become new stars, while out in the disc you can have the formation of planets. If the material can't coalesce to form a planet (maybe it is disrupted by the gravity of another body, maybe there isn't enough material nearby, etc), you may have smaller chunks of rock. Others may break off of another body, such as cometary tails, or even be launched from another planet by a significant impact.", "topk_rank": 2 }, { "id": "corpus-125049", "score": 0.7314789295196533, "text": "Not every element. The hydrogen on Earth could be primordial (produced in the first few minutes of the universe). The helium on Earth is mostly from radioactive decay (any helium that was here to begin with has long since escaped Earth's atmosphere). But any element heavier than lithium - aka most of them - was produced in stars.", "topk_rank": 3 }, { "id": "corpus-310094", "score": 0.7313646674156189, "text": "Elements up to lithium were created in the big bang, up to iron are created in stars, and up to uranium are created in supernovae. Elements bigger than uranium are generally created at atom smashers on Earth.", "topk_rank": 4 }, { "id": "corpus-324920", "score": 0.7309142351150513, "text": "Well, our planets formed from the same gas/debris cloud that our sun did, itself a remnant of older stars which had gone super nova. Not all elements are created in [active] stars though, as stars through fusion can only create the elements up to Iron... everything else came from supernovae.", "topk_rank": 5 }, { "id": "corpus-323305", "score": 0.7309128642082214, "text": "Nuclear fusion in stars produces all the elements up to iron - it requires an *input* of energy for elements heavier than iron to form. They are only formed during the massive energy output of a supernova (not a nova - a nova is just an outburst of surface fusion, it doesn't destroy the star). You asked how this enriched gas gets to our solar system: gas flows out from stars, novae, and in particular supernovae, so that the surrounding region now has more heavy elements in it (we call this a \"higher metallicity\"). This \"metal-rich\" gas mixes in with the rest of the gas in the galaxy (the \"interstellar medium\") so the net effect is that the gas of the Milky Way is just a little higher metallicity. New stars form from this enriched gas, and will have more heavy elements than the previous stars.", "topk_rank": 6 }, { "id": "corpus-242372", "score": 0.7298850417137146, "text": "2) In supermassive stars: The heaviest element found in heavy stars is iron, since it's the product of the last energetically favorable fission process. Heavier elements can be created when a heavy star goes supernova, since huge amounts of excess energy are released in that process and some of it can go in to forming heavy elements. In such a process heavier elements might be formed, but definitely not stable heavy elements in large quantities, since we would be able to see them in the line spectra of other stars containing such elements (those stars would be formed from the supernova remnants). It's really on a gray area to say that a black hole contains such and such elements, since we define different elements as nuclei with different amounts of protons. We can't make any measurement on the inside of a black hole and thus we can in no way \"count\" the amount of protons in nuclei. Hell, we can't even see any nuclei (or anything else).", "topk_rank": 7 }, { "id": "corpus-833329", "score": 0.7285597920417786, "text": "I have an understanding that the production of iron is what will kill a star, I understand that stars are fine before this production and that makes sense to me. Here is the issue, extremely large stars build up layers and layers of heavier elements such as gold and uranium, they will build this up just fine, but the moment they start to create iron they rapidly will do so and then either die, become a white dwarf, or super nova. Why specifically iron and why can larger stars produce heavier elements but still collapse when they produce iron?", "topk_rank": 8 }, { "id": "corpus-305403", "score": 0.7272583842277527, "text": "Stars emit a continuous spectrum of photon energies. But every element has a very narrow range of frequencies which correspond almost exactly to the energies of its electron orbitals. So atoms in the star filter out certain frequencies from the continuous emission spectrum. We can measure the [absorption spectrum](_URL_0_) of the star, and compare it to what we know about different atoms and molecules to determine what the star is made of.", "topk_rank": 9 }, { "id": "corpus-311914", "score": 0.7267962098121643, "text": "I'm sure that there is a way to tell from spectral lines the abundance of an element in a star but I don't know it. I can tell you however one of the ways we know the abundance of elements in the Sun. There's a kind of meteorite called [chondrites](_URL_0_). They are made up of chondrules which were the first large solid objects in the solar system. I say large but they're almost always less than a millimeter in diameter. These little balls of matter represent the makeup of the protoplanetary disk which formed around the Sun and eventually became the planets and asteroids. By analyzing their composition and the abundance of each element in them we can get a good idea of the overall abundance in the solar system as a whole, including the Sun.", "topk_rank": 10 }, { "id": "corpus-290498", "score": 0.7267512679100037, "text": "Here is a really good link that explains where all elements come from (including gold and silver in your title). The tl;dr version - all elements, including gold, silver, uranium and mundane elements like carbon and silicon all come from supernova. You (and me) are made out of the same stuff as the stars _URL_0_", "topk_rank": 11 }, { "id": "corpus-40044", "score": 0.7263737320899963, "text": "As stars die they start producing heavier and heavier elements. Then when they go supernova these elements are flung into space as dust and gas (star dust). This then coalesces to form planets, just as Earth did. You are made from matter from the earth, hence you are made of stardust.", "topk_rank": 12 }, { "id": "corpus-311167", "score": 0.7248344421386719, "text": "There's not a whole lot of those elements. Unless we're talking about primordial Population III stars, the star will have formed out of gas that was previously enriched by supernovae and stellar winds, so stars will start out with some C, N, and O. Prior to the onset of helium burning as a dominant power source, there can still be small amounts of helium fusion which can then produce C/N/O. It doesn't take very much of those to permit the CNO cycle to occur. Also, for context, the proton-proton chain is very hard to complete, meaning that protons have an absolutely miniscule chance of fusing into deuterium, and deuterium can then be photodisintegrated. Only because of the gargantuan number of protons bouncing around in the Sun's core does the p-p chain manage to produce the Sun's power. So even if there isn't much C/N/O, the process is so much more efficient (at high temperatures) than the p-p chain that it can still dominate.", "topk_rank": 13 }, { "id": "corpus-12005", "score": 0.7247800230979919, "text": "Understand that it takes an incredible amount of energy to do it, but yes - it's the basis of how fission & fusion nuclear power work, but the materials we're using have little other practical function (no one's going to get uranium plated teeth or use it in place of steel). In nature, stars are doing the majority of mixing & mashing of atomic structural stuff in regards to other elements (starting from hydrogen and working up heavier elements, up to iron). Elements heavier than Iron are almost exclusively going to come from super novae (and/or other equally as violent reactions in the Universe's early days).", "topk_rank": 14 }, { "id": "corpus-307618", "score": 0.7242786884307861, "text": "Stars only fuse up to iron. Supernovae make the heavier elements.", "topk_rank": 15 }, { "id": "corpus-307266", "score": 0.7240831851959229, "text": "In general younger stars are more metal rich than older ones. In the past the universe was only made up of hydrogen and helium. As stars formed they underwent a process called nucleosynthesis which creates heavier elements. When massive stars (stars in the early universe were often much bigger than now) went supernova they created even more exotic and heavy elements. As this process of stars forming and dying continues you create a universe where there is more metalic elements (for stars this is everything that is not helium or hydrogen) and so the metalicity of the entire universe goes up. So we expect stars formed now to on average have higher metalicity than ones of the past.", "topk_rank": 16 }, { "id": "corpus-168433", "score": 0.723060667514801, "text": "It can be fused into a new element (its the only way to get higher elements) the problem is the fusion takes more energy than it produces so it doesn't happen as a fuel source for stars. When a star goes supernova though it can fuse higher elements, the more massive the star, the higher the elements it can fuse. Its a short process though so the abundance of elements above iron drops off quickly and is much lower.", "topk_rank": 17 }, { "id": "corpus-287240", "score": 0.7228297591209412, "text": "Carbon is not required to form stars. The fusion in most stars for most of their lives is powered purely by hydrogen. When a fairly massive star uses up all it's hydrogen, it starts fusing heavier elements all the way up to iron. Carbon is produced along the way.", "topk_rank": 18 }, { "id": "corpus-324322", "score": 0.7222222089767456, "text": "Stars do not chemically burn like a campfire. Rather, due to the intense heat and pressure of the core, a star fuses hydrogen into helium which releases a tremendous amount of energy which goes towards heating the star and producing light. Depending on a star's mass and age other elements may be fused, which may release energy or even take energy.", "topk_rank": 19 } ]

[ { "id": "corpus-325394", "score": 0.7493796944618225, "text": "Multiple times. There are ferns that are [trees](_URL_0_), grasses that are [trees](_URL_1_), gymnosperms (conifers and ginkos), and many different lineages with trees within the flowering plants." } ]

[ { "id": "corpus-278754", "score": 0.7034959197044373, "text": "The key part of this question is \"what is an individual organism?\" And the truth is that while the idea of individuals works pretty well for things like mammals, which in fact not dividable, for things like clonal trees or coral or whatever the whole idea doesn't quite fit. So it's better to think about genets and ramets. A genet is all the genetically identical organisms. If you've got a tree that spreads by root systems (like Pando, for instance), the whole interconnected whole is a genet, while the individual trunks are ramets. Colloquially, \"tree\" usually refers to a ramet, not a genet, so usually you'd say a tree has died if a particular ramet has died (IE, you've got a dead trunk and a bunch of dead leaves on it).", "topk_rank": 0 }, { "id": "corpus-301513", "score": 0.7034075260162354, "text": "Probably depends on the amount of conductive tissue (xylem, phloem) that each tree contributes. It's likely that the root systems aren't fused so each tree is contributing based on root volume. I'm not entirely sure but I'm an Arborist with an educational background in tree biology and have seen a fair amount of trees fused together. I once found a sugar, Norway, and red maple all growing on what appeared to be one stem.", "topk_rank": 1 }, { "id": "corpus-238993", "score": 0.7014613747596741, "text": "Basically, only because our models say it is more likely to have one root than multiple to the tree of life. Here's more info on the [Last Universal Ancestor](_URL_0_) if interested. However, you could still be right for reasons that the models do not take into account.", "topk_rank": 2 }, { "id": "corpus-311987", "score": 0.7001751661300659, "text": "From an evolutionary standpoint, those trees aren't that old. I'm too lazy to dig up the rate of evolution in plants, but they probably are over millions of years rather than a few hundred (or even thousands). These trees are old compared to human lifespans, but they're not \"really old\". And remember, these trees aren't sterile, so they probably intermixed genetically with the same plants around them. I doubt you'd find anything substantially different from a genotype or phenotype level between extant members of the species and these individuals.", "topk_rank": 3 }, { "id": "corpus-317254", "score": 0.6999768018722534, "text": "Yup. Here's the eukaryotic phylogenetic tree: _URL_0_ Also, in case you aren't aware, plants, animals, and fungi are all part of the \"eukaryote\" domain. Right now most biologists accept that there are three domains of life: bacteria, archaea, and eukaryotes. So not only do you share an ancestor with bananas, but you and bananas are like brothers and bacteria are your second cousin. But, ultimately, we are pretty damn sure that all currently living life on this planet derives from a single evolution of life. There is one root to the tree of life, not multiple trees. Strictly speaking, the relationship between branches is still unclear. Clearly everything shares an ancestor, but whether, for example, the whole domain of archaea share a common ancestor, or whether there should be even more domains, is not clear. We're still working on the details.", "topk_rank": 4 }, { "id": "corpus-85885", "score": 0.6982367038726807, "text": "Trees can indeed meld together either [naturally](_URL_2_) or [with our help](_URL_1_), becoming one connected system where nutrients and water can flow across the boundary through the usual vascular processes. It can even happen across species boundaries, although this is less likely to happen without human assistance. It's actually believed the world's largest single living thing (by weight) is [a colony of naturally cloned asp trees called Pando](_URL_0_) which all share one root system.", "topk_rank": 5 }, { "id": "corpus-253314", "score": 0.695916473865509, "text": "Even if two lineages converged independently on identical genetic makeup (and this is pretty much impossible) they still wouldn't converge on the graph. This is because phylogenetic graphs don't measure _genetic_ similarity, they measure actual lines of descent. In practice, genetics is a large part of how we figure out lines of descent, but genetics isn't what the tree is about. Despite being genetically identical, properly speaking the ones descended from species A should be on the branch from A, and the ones from B should be on the branch from B. That said, it _is_ theoretically possible for branches to fuse back together. This occurs when two species hybridize to form a new species. Common ways of dealing with phylogenetic trees and cladograms don't handle this very well or ignore it (which isn't _usually_ an issue)", "topk_rank": 6 }, { "id": "corpus-311949", "score": 0.6948704123497009, "text": "Your individual experience doesn't necessarily represent the norm. It is actually pretty common for the stump of a tree to continue living. The American Chestnut, in particular is a hair's breath from extinction by the grace of this very mechanism. Early last century, a fungal disease called Chestnut blight was introduced into the tree's native range in the Appalachias via New York. In the ensuing decades, the specie was virtually wiped out as the above ground portions of affected trees die after the infection encircle the trunk. The still living roots of some trees however still continue to send up shoots. They grow for a short while before ultimately succumbing to the fungus again. So although \"functionally extinct\" as they are no longer able to effectively breed and propagate naturally, enough of the species still exist, maintaining a meaningful Gene pool that scientist hope to be able to revive with a number of [ongoing efforts](_URL_0_).", "topk_rank": 7 }, { "id": "corpus-283536", "score": 0.6943028569221497, "text": "I think this question is making some assumptions about evolution that I'm not so much a fan of. Plants have evolved over a really long period of time (longer than any animal) to be really good at what they do. Assuming that evolution eventually leads to sentience sapience or animal form is pretty determinist. It sort of follows from that logic that the trajectory of all evolution is toward animals. This isn't the case, evolution isn't linear. There is no \"hierarchy of organisms\". Plants fill a separate ecological niche than animals and there's pretty much no reason for them to start behaving like another kingdom. If plants eventually evolved sentience and started moving around, they'd probably do it in a radically different way than animals do because they posses a pretty disparate genetic toolkit to the animal kingdom.", "topk_rank": 8 }, { "id": "corpus-132988", "score": 0.6940832734107971, "text": "Absolutely. Not only are there common ancestors for plants, but *all living things* share a common ancestor. At some points, all of the various kingdoms of life diverged from the same organism.", "topk_rank": 9 }, { "id": "corpus-645575", "score": 0.6918041110038757, "text": "I was looking at sixes last and was wondering why you don't have trees or plants with eyes. Yes, I know, trees don't have a nervous system to process the information from the 'eyes', but why did trees evolve that way?", "topk_rank": 10 }, { "id": "corpus-644756", "score": 0.6882736682891846, "text": "are the branches of trees just trees growing out of other trees", "topk_rank": 11 }, { "id": "corpus-283010", "score": 0.6879976987838745, "text": "A fun plant example is ~~new~~ old world \"[cacti](_URL_3_)\" (Euphorbaceae) and ~~old~~ new world [cacti](_URL_4_) (Cactaceae). Euphorbs aren't actually cacti at all and the two plant families are quite evolutionarily distant (rosids vs close relative to asterids, a split that occurred > 100mya)", "topk_rank": 12 }, { "id": "corpus-148049", "score": 0.6873990893363953, "text": "It is called evolution. Taller plants get more sunlight and shade out competition. Only a certain amount of height can be attained by plants without using a woody core. The first woody plants had an advantage. But they differed from modern trees. They had much more bark. Mutations occurred and continue to occur. Most are unfavorable. But a very few are favorable and they are conserved in the DNA.", "topk_rank": 13 }, { "id": "corpus-123044", "score": 0.6867069005966187, "text": "Actually, the record is [somewhat over 5000 years](_URL_0_). [Clonal trees](_URL_0_#Clonal_trees) may be very much more. Possibly up to a million years. As to why - trees have a lot of things going for them. They can survive when some bits die, they retain the ability to grow new bits, once they've adapted to cope with local pests they'll probably stay that way for ever...", "topk_rank": 14 }, { "id": "corpus-122919", "score": 0.6858859062194824, "text": "If I'm not mistaken, there was a relatively long period of time where trees had evolved but the cells that enabled trees to form rigid structures could not be broken down through biological processes (it took a long time for bacteria, algae, fungi to evolve the ability to digest). During this period, trees would die but not decompose. Forests would become massive areas of dead wood. These would catch fire and created staggeringly large fires. Much of the coal we consume today formed as a result of this period. Edit: Thanks good folk for the gilding and the great info. I've really enjoyed learning more about this interesting time.", "topk_rank": 15 }, { "id": "corpus-49092", "score": 0.6848408579826355, "text": "Trees do have a defined structure. Roots at the bottom to search for and feed off of minerals, leaves up top to feed off of sunlight and carbon dioxide while expelling oxygen, and a trunk in the middle to propel the leaves higher if needed to get better sun coverage. Branch structure seems random, but so do blood vessels and capillaries. EDIT: the trunk also propels the branches higher off the ground to deter animals from eating their seeds, usually in fruit, that make more trees.", "topk_rank": 16 }, { "id": "corpus-303649", "score": 0.6841791868209839, "text": "Trees were one of the most disruptive life forms to ever appear, and the defining characteristic of the [Carboniferous era](_URL_5_). There was about a 100 million year gap between when trees first appeared, and when a fungus capable of breaking them down appeared. Before that, trees would lie where they fell indefinitely, until they were either buried or burned. This led to enormous carbon sequestration, and the rich coal seams throughout the world. It also brought global oxygen levels past 35% (vs 20% today), which allowed the largest dinosaurs to evolve. Most of those would asphyxiate in today's atmosphere.", "topk_rank": 17 }, { "id": "corpus-298038", "score": 0.6832730770111084, "text": "You should tag this \"Paleontology,\" as archeology only pertains to humans. From a paleontological perspective, the species concept isn't really a meaningful one. Remember, every lineage is a record of continuous change, even when the rate of that change varies through time. There are generally no points where you can draw a line marking the transition to a new species, with exceptions being things like self-fertilizing plants that experience full-genome duplication and become genetically isolated from their immediate relatives. Since every lineage has existed since the theoretical single common ancestor, all lineages are the same age.", "topk_rank": 18 }, { "id": "corpus-298520", "score": 0.6832149624824524, "text": "Two reasons: 1. They're modular organisms, which means they grow by adding on new parts which are not necessarily necessary or dependent on previous parts, and lose those parts similarly. 2. They are totipotent on a different level. They are composed essentially of stem cells which can reproduce any part at will. Like how a lizard can lose its tail and regrow, except all over. If you think about those two things, and you know that, for example, Aspen forests are essentially all connected underground and are considered one gigantic organism, you would wonder why any tree would ever die at all.", "topk_rank": 19 } ]

[ { "id": "corpus-325395", "score": 0.7786010503768921, "text": "They are stars in our galaxy, much closer than the galaxy in the image." } ]

[ { "id": "corpus-312728", "score": 0.7391234636306763, "text": "**Short answer:** Yes! **Long answer:** You would be broadly interested in the Messier catalog. Compiled by the French astronomer Charles Messier in 1771, the catalog contains about 100 objects that are visible in the night sky that aren't just stars. These objects include globular clusters, nebulae, and galaxies. Many of these are some of the nearest objects of their kind, and as such have been well studied with the Hubble and other telescopes. [Take a look.](_URL_0_) Our nearest galactic neighbor, Andromeda (or M31 as Messier called it) looks sorta like [this](_URL_1_) in the night sky. Can you guess which blob it is :P", "topk_rank": 0 }, { "id": "corpus-323885", "score": 0.7389637231826782, "text": "We are, relatively speaking, near the outer fringe of the galaxy. [Here's an illustration](_URL_0_). And it looks like [This](_URL_1_).", "topk_rank": 1 }, { "id": "corpus-297319", "score": 0.7388971447944641, "text": "I believe, like most spiral galaxies, there is a super massive black hole. You might think \"but the why is it bright?\" And I believe that'd because there are way more stars at the center which rotate the black hold making it look like there's a giant bright ball at the center.", "topk_rank": 2 }, { "id": "corpus-18552", "score": 0.7385839223861694, "text": "Those dark spots probably correspond to the parts of the universe which are occluded by the bulk of the disk of our galaxy. As we look in that direction, we can't really see past all the gas and dust that comprises the main disk of the milky way.", "topk_rank": 3 }, { "id": "corpus-320236", "score": 0.7384540438652039, "text": "They're not just depicted that way, they are that way! [This](_URL_0_) is a photo of the Andromeda galaxy. It's not an illustration or false color, it's just a photo. You can even see it with your own eyes if the sky is dark enough, in fact the only part you'll see is the bright center portion. Galaxies are densest at the center, so that's where the brightest light comes from.", "topk_rank": 4 }, { "id": "corpus-321202", "score": 0.7383898496627808, "text": "It's pretty typical for our neighborhood of the galaxy, maybe a little closer than average. Here's an interactive 3-d map of many (but not all!) of the nearest stars, so you can see for yourself: _URL_0_", "topk_rank": 5 }, { "id": "corpus-270640", "score": 0.7383295893669128, "text": "Those are dark, dense molecular hydrogen clouds, known as [Bok globules](_URL_0_). The Carina Nebula is a stellar nursery where stars are actively forming. These starts out as massive cold clouds of hydrogen, but as they begin to collapse from their own self-gravity, stars begin to form in the denser chunks. Once these stars begin emitting lots of photons, they will heat and ionize the surrounding gas, causing it to glow - thus all the pretty colors of the surrounding area. The heating will also cause the gas to expand, and generally prevent any further star formation, as well. Any remaining dense clumps will be harder to heat, though - the exterior will ionize and glow, but it's difficult for the photons from the stars to penetrate deep into those clumps. Thus, they appear dark compared to the surrounding area, but with a bright ionized perimeter.", "topk_rank": 6 }, { "id": "corpus-71865", "score": 0.7382433414459229, "text": "You don't have to, in most cases. [This](_URL_0_) is a picture of our closest neighbor galaxy, Andromeda taken from earth. It's that smudgy bit on the right. All of the other stars in that picture are within our galaxy. The problem is, we are pretty well smack dab in the middle of the Milky Way (in terms of it's thickness), so we always have to look out past stars in the Milky Way to see anything else. I have a feeling you are referring to pictures such as [this](_URL_1_). Those types of pictures are artists' conceptions of the galaxies, extrapolated from data collected by astronomers. [This](_URL_2_) is what the data that most astronomers collect looks like.", "topk_rank": 7 }, { "id": "corpus-323329", "score": 0.738220751285553, "text": "Well, first of all, that isn't a photograph. It is more along the lines of \"an artist's conception.\" Secondly, we can obtain information of structures like this one through a plethora of techniques like using different wavelengths for telescopes (those specific lobes were viewed with a gamma ray telescope) or gravitational lensing of other galaxies. All of our galactic observations are taken from essentially the same place. We do have distant probes like Voyager and New Horizons, but they are still essentially in the same spot we are.", "topk_rank": 8 }, { "id": "corpus-139862", "score": 0.7381225228309631, "text": "Forget galaxies, we can't even get to the nearest star in our lifetimes. But that doesn't prevent us from seeing it. I think the confusion might be because you can't see far away destininations on earth. The reason you can't see far away destinations on earth is because the curve of the earth is in the way. Let's pretend there are two ants on the surface of a sphere. The further away from each other they crawl, the harder it becomes for them to see each other. That's exactly what's happening on earth. The farther away from us something becomes, the harder it is to see. But when we're talking about stars or other galaxies, nothing prevents us from seeing them because nothing is getting in the way. Sure they look smaller as they get farther away and their light gets fainter, but they never disappear completely. That's why we can zoom in on these stars and take their picture.", "topk_rank": 9 }, { "id": "corpus-124069", "score": 0.7380924224853516, "text": "It's called scintillation. Since stars are so far away, the light they emit is very close together so it looks like just a point of light. Since the light is so close together it interferes with other light from the same star. Sometimes it cancels out, sometimes it makes it brighter. When you see a \"star\" that isn't scintillating like that, it's probably a planet. Since they're closer, they appear larger than stars and the light isn't crowded close enough to interfere as much so the light looks steadier. If you're out around 4am or so in the US (or similar latitude), look east. Jupiter is very visible right now and you can see the difference.", "topk_rank": 10 }, { "id": "corpus-54860", "score": 0.7380282282829285, "text": "I've always wondered. Everything of the Milky Way is an artist's impression, but there are two caveats. First, astronomers have mapped the Milky Way with what I would call pretty high precision, so we know what it looks like. Second, scientists have taken photos of Andromeda, our neighbor galaxy. _URL_0_ _URL_1_", "topk_rank": 11 }, { "id": "corpus-1979602", "score": 0.738013744354248, "text": "So I'm in the army and deployed to Afghanistan. The closest city to me has no electricity so at night it becomes pitch black. Yesterday I layed on the ground looking at the stars and was amazed to see the Milky Way. Ive never seen it so clear in my life, I could even make out the dark strip that runs along the center. It's an amazing experience to see the universe around us with no light pollution. It got me thinking, when I saw the Milky Way, what exactly was I looking at? Am I seeing our own spiral arm or another, am I looking toward the center or out? It would be awesome to have some perspective on what I'm looking at.\n\nTL;DR: Saw the Milky Way, what am I looking at?", "topk_rank": 12 }, { "id": "corpus-319100", "score": 0.7377687096595764, "text": "When looking beyond the galaxy, we usually look \"above\" or \"below\" the galactic plane. For example, [this](_URL_0_) map of galaxy locations.", "topk_rank": 13 }, { "id": "corpus-21875", "score": 0.7375302314758301, "text": "It's too dim, and it's not a single object. It's a loose pattern in the position of galaxies, and those galaxies are much, much, MUCH too dim to be seen with the naked eye individually. That being said, you might be surprised at how large some objects actually are in the sky. The full size of the Andromeda galaxy - the closest major one to the Milky Way - in the sky is [several times larger than the full Moon](_URL_0_). But the outer parts are too dim for naked-eye viewing.", "topk_rank": 14 }, { "id": "corpus-161599", "score": 0.7373899221420288, "text": "We haven't. Any \"picture\" you've seen is an artist's rendition or computer simulation based on what we know so far about our own galaxy. In fact, if you look at these images chronologically over a few decades, you will see changes indicative of newly gained knowledge.", "topk_rank": 15 }, { "id": "corpus-322199", "score": 0.7372541427612305, "text": "There are no photos of the entire Milky Way from outside of it. Any photo of an entire galaxy which is labeled as the Milky Way is either another galaxy which has similar structure, an \"artist impression\" or some form of simulation.", "topk_rank": 16 }, { "id": "corpus-311150", "score": 0.7370874881744385, "text": "You cannot see individual stars (including in [satellite galaxies](_URL_0_) to the Milky Way). You can see the collection of stars together looking like a blob of light, which means that you can see things like the Andromeda Galaxy with your naked eye, for the reasons listed in the link.", "topk_rank": 17 }, { "id": "corpus-301473", "score": 0.7370618581771851, "text": "At night, in areas without light pollution from cities, you can see part of the rest of our own galaxy. We're about midway out on just one of the arms. If I recall correctly, the only part we can't see at all is a wedge blocked by the cloudy galactic core. Pics of the whole galaxy are computer generated but we can use what we can see from here to extrapolate the \"view from above.\" Map: _URL_0_ View at night: _URL_1_", "topk_rank": 18 }, { "id": "corpus-317361", "score": 0.73646479845047, "text": "Many hundreds of millions of stars. Look at [this](_URL_0_) ultra high resolution picture of the Andromeda Galaxy. This is a zoomable image, be sure to zoom *way* in. Each point of light is a star or star cluster. Note that in the bright core there are so many stars it becomes difficult to pick out individual ones.", "topk_rank": 19 } ]

[ { "id": "corpus-325396", "score": 0.7646741271018982, "text": "From wikipedia: _URL_0_ > Reactions that take place on polar stratospheric clouds (PSCs) play an important role in enhancing ozone depletion. PSCs form more readily in the extreme cold of Antarctic stratosphere. This is why ozone holes first formed, and are deeper, over Antarctica. Early models failed to take PSCs into account and predicted a gradual global depletion, which is why the sudden Antarctic ozone hole was such a surprise to many scientists. There is a temperature difference between the north and south poles that accounts for the difference in the depletion of each." } ]

[ { "id": "corpus-248551", "score": 0.7248626351356506, "text": "it's the reverse, for two reasons. 1. the thickness of the atmosphere varies across the globe but is generally thicker at the equator and thins out elsewhere; therefore the air is 'thinner' at altitudes the further south or north you go - to the point that if Everest was in Europe it would likely be unclimbable without oxygen. This is also part of the reason the mountains in the Antarctic are more challenging to climb than equivalent heights in the Himalaya. (this fact caused massive issues with estimating the need for oxygen in the late 19th/early 20th C). 2. Also because although Chimborazo is higher than Everest from the centre of the earth, it's not higher from sea level, and atmospheric depth starts at sea level, so the air is still 'thicker' on Chimborazo.", "topk_rank": 0 }, { "id": "corpus-289598", "score": 0.720596194267273, "text": "Well, lets ignore the shortened period of day and just concentrate on the maximum intensity of UV radiation at different times of year, which is not the same as talking about UV intensity at different latitudes (due to differences in ozone concentration in the stratosphere with latitude). Obviously, we would assume a sunny day with the same atmospheric ozone content (no fair doing it on a sunny day and an overcast day). I would speculate that the angle of incidence on the earth's atmosphere would cause more UV radiation to be screened away. My guess is that if the sun's rays must pass through more ozone, less UV will reach earth's surface. Thus, during times of the year (or day!) when the sun is lower in the sky, less UV radiation will reach earth's surface. Also, googling around found me this [sweet map!](_URL_0_) you can see how heterogeneous atmospheric ozone is! Sweet huh?", "topk_rank": 1 }, { "id": "corpus-1314", "score": 0.711016833782196, "text": "Ozone is constantly being created in our upper atmosphere because of UV radiation from the sun. It's a good thing too, because otherwise that same UV radiation would cause all kinds of trouble for humans here on the ground. But in the previous century we had a number of machines, chemical processes (and even fridges) releasing nasty chemicals into the atmosphere that would hurt this ozone layer. This was visible in a measurable lack of ozone in the most fragile spots, around the Earth's poles. These \"holes\" in the ozone layer grew to an alarming size. Thankfully the use and release of these chemicals were banned, and now, slowly, we can see the ozone holes shrinking again.", "topk_rank": 2 }, { "id": "corpus-76330", "score": 0.7101458311080933, "text": "Most of the world's oxygen comes from the ocean. About 70% actually. And it isn't winter everywhere at the same time, in fact it's pretty much always winter equally globally. The southern hemisphere is actually in Summer right now. Perks of living on a big wet ball, things are pretty much always balanced out", "topk_rank": 3 }, { "id": "corpus-318212", "score": 0.7083754539489746, "text": "You don't even have to go to Antarctica - [Australia has problems](_URL_0_) (and [another paper](_URL_1_), sorry if pay-walled) with high levels of UVB radiation that can cause sun burn quite a bit faster than in most places on earth. I'm not sure about other parts of the spectrum, though.", "topk_rank": 4 }, { "id": "corpus-316419", "score": 0.7082622647285461, "text": "Longer, darker winters allow for more clouds containing Ozone-breakdown chemicals (like CFCs) to develop, and in the spring time, when the sun's UV returns, the Ozone begins depleting most strongly. _URL_0_", "topk_rank": 5 }, { "id": "corpus-16548", "score": 0.7055540680885315, "text": "Ozone has the chemical formula O*_3_*. It is constantly formed in our atmosphere. Ozone absorbs harmful UV light so it reduces the amount that reaches the ground. Hole isn't the best description really, there is a lot less of it over Antarctica and the southern parts of Earth. CFCs (chlorofluorocarbons) can react with ozone and turn it back into molecular oxygen (O*_2_*). These were discontinued but they are still present in the atmosphere. It's still there, but it does appear to be getting better. Come visit New Zealand in summer, you can get sunburn in as little as 20 minutes if you aren't careful. This can largely attributed to the ozone hole.", "topk_rank": 6 }, { "id": "corpus-306374", "score": 0.7049902677536011, "text": "Better but not yet back to normal. Concentration of [ozone-depleting gases](_URL_2_) has been slowly decreasing since the Montreal Protocol limiting them was signed in the 1990s, and the [amount of missing ozone](_URL_0_) has been decreasing since around the year 2000. Currently the \"hole\" is almost halfway back to its natural state. It's a pretty great example of how human-caused changes in climate can be dealt with through international agreements. Perhaps we should learn from it! _URL_3_ _URL_1_", "topk_rank": 7 }, { "id": "corpus-241227", "score": 0.7040408253669739, "text": "Read your own source carefully again, it has the answer for you. There are a few steps: * CFC's Emitted mostly in northern hemisphere. * Thorough mixing occurs in lower atmosphere over a period of years (CFC's are mostly non-reactive and insoluble) * A portion of well-mixed tropical air rises from the lower atmosphere into the stratosphere * Prevailing winds direct this air towards the poles * At the south pole, the geography of the region encourages the formation a stronger polar vortex than at the north pole, and this creates conditions favorable to ozone-depletion by CFC's", "topk_rank": 8 }, { "id": "corpus-244722", "score": 0.7033663988113403, "text": "That layer of the atmosphere, from about 10 km up to 50 km, is called the stratosphere, and one of its defining properties is that temperatures increase with height. The stratosphere has a relatively high concentration of ozone (O3). When ozone is struck by UV rays from the sun, it splits into molecular oxygen (O2) and atomic oxygen (O). The atomic oxygen recombines with molecular oxygen to reform ozone, and in doing so it gives off heat. This heat warms the stratosphere. Basically, it's a mechanism for converting energy in the form of UV rays to energy in the form of heat.", "topk_rank": 9 }, { "id": "corpus-323052", "score": 0.7022051811218262, "text": "There is a natural variability in the ozone layer, caused in-part by fluctuations in temperature. Like any other geophysical system, there is a large amount of noisy variability on top of a physical trend. The ozone hole will be larger some years, smaller in others, but on average it is returning to its historical state as we have curtailed activity that was eroding ozone.", "topk_rank": 10 }, { "id": "corpus-58582", "score": 0.7017737627029419, "text": "Not every spray can deplete the ozone layer, only those which contain [CFC](_URL_0_) do. Once we realized the bad effects of CFC (and other similar chemicals) we stopped using them.", "topk_rank": 11 }, { "id": "corpus-27977", "score": 0.7006881833076477, "text": "The Ozone layer is a part of our atmosphere made up of Ozone (which is a molecule with 3 oxygen atoms. Oxygen in the air we breathe is O2, Ozone is O3). It is important in that it protects us from the full blast of Ultraviolet rays that come in from the sun. Back in the 1980's we noticed that there was a gap, a hole in the ozone layer near the south pole. It was determined that some of the chemicals we use (Chloroflourocarbons or CFC's) were the cause of this. These were commonly used as propellants in spray cans, like cans of hair spray as an example. As we started reducing their use, the hole in the Ozone layer has actually been getting smaller (which is a good thing).", "topk_rank": 12 }, { "id": "corpus-317892", "score": 0.6975769400596619, "text": "The ozone holes occur in the polar spring (~ March in the North, ~ September in the South), and result from chemical and weather conditions. Primarily, these holes let in more UV radiation, which is bad for humans/plants/life (more UV causes more cancer, destroys certain cells, and is generally detrimental to healthy biology). The climate impacts are not as dramatic, or at least not while the holes only last for a season. Currently, stratospheric ozone depletion causes a slight cooling (see the [Wiki page](_URL_0_)), but only slight. Not a concern when compared to other warming/cooling sources. However, the chemicals that form the hole tend to be greenhouse gases, or interact strongly with greenhouse gases, and may be an indicated of increased emission of these species.", "topk_rank": 13 }, { "id": "corpus-135318", "score": 0.6958801746368408, "text": "Greenhouse gases are not related to the ozone hole. The ozone hole over Antarctica was caused by CFCs and the hole formed there because it gets so cold over the winter that a \"polar vortex\" forms. This is like a big whirlpool high in the air 24/7 during winter months. Air containing CFCs get sucked into the vortex and accumulates there. Then, in springtime UV rays hit the CFCs and break out the chlorine which destroys ozone. Since the CFCs are concentrated over Antarctica then that's where the hole forms.", "topk_rank": 14 }, { "id": "corpus-325194", "score": 0.6939512491226196, "text": "[Yup.](_URL_2_) They still is one, but it's predicted to become smaller--which is thankfully due to the drop in [atmospheric CFCs](_URL_3_) since they have been banned/phased/phasing out. However, it's best not to think of it as a literal hole, it's the reduced concentration in Ozone in one strata of the atmosphere. It's more like a \"thinning.\" Not only that, the size of the thinning is seasonal and happens mainly at the poles--though NASA released a report predicting a future global Ozone depletion had CFC emission not slowed down. Here's a couple more images: * [Arctic Ozone depletion](_URL_1_) * [Seasonal Ozone minimums over the years](_URL_0_)", "topk_rank": 15 }, { "id": "corpus-319463", "score": 0.6934852004051208, "text": "Because of tectonic shifts. The tectonic plate that Antarctica was on, and was once apart of Pangea of course, split and moved to the south pole, where it gets no sunlight during winter, and is like hardcore mode in Minecraft", "topk_rank": 16 }, { "id": "corpus-35182", "score": 0.6933229565620422, "text": "No. The global oxygen level do not fluctuate that much if at all from things like loosing leaves because half the world is always going to be in summer. Also equatorial rainforests are always in summer, and contribute the most of anything to filtering air.", "topk_rank": 17 }, { "id": "corpus-86741", "score": 0.6913532614707947, "text": "They are much more than 10,000 km apart, so it's not easy for species to spread from one to the other. Antarctica has a lot of dry land, and is incredibly cold. The Arctic has dry land at medium latitudes, and only floating ice at the extreme latitudes.", "topk_rank": 18 }, { "id": "corpus-297723", "score": 0.6902568936347961, "text": "Yes. 68% of the Earth's landmass is in the Northern Hemisphere, and there's a lot of landmass inside the Arctic Circle, whereas the South Pole is surrounded by ocean water. Now water has a high specific heat, which means it's harder to heat but also cool it down. It means more stable temperatures, so that ocean surrounding Antarctica moderates the temperature and is more efficient at containing masses of polar air inside the Antarctic Circle.", "topk_rank": 19 } ]

[ { "id": "corpus-325397", "score": 0.760910153388977, "text": "[Here is a good summary](_URL_0_) Plants and animals share a lot of structure at the cellular level. Cells have chromosomes, ribosomes, phospholipid bilayers for cell membranes, they all use DNA to store genetic information, various forms of RNA are common to both plants and animals, etc." } ]

[ { "id": "corpus-283536", "score": 0.7217223644256592, "text": "I think this question is making some assumptions about evolution that I'm not so much a fan of. Plants have evolved over a really long period of time (longer than any animal) to be really good at what they do. Assuming that evolution eventually leads to sentience sapience or animal form is pretty determinist. It sort of follows from that logic that the trajectory of all evolution is toward animals. This isn't the case, evolution isn't linear. There is no \"hierarchy of organisms\". Plants fill a separate ecological niche than animals and there's pretty much no reason for them to start behaving like another kingdom. If plants eventually evolved sentience and started moving around, they'd probably do it in a radically different way than animals do because they posses a pretty disparate genetic toolkit to the animal kingdom.", "topk_rank": 0 }, { "id": "corpus-257505", "score": 0.721367359161377, "text": "Monotremes (the Platypus and the Echidna are the only examples I know of) shared a common ancestor with other mammals about 160 million years ago. We can call them our extremely distant cousins (actually, the most distant mammal cousin).", "topk_rank": 1 }, { "id": "corpus-254689", "score": 0.7201359272003174, "text": "All species have a common ancestor, but that ancestor did not have a brain, heart or true eyes. Brains have evolved in animals at least [9 times](_URL_0_). Eyespots evolved independently [around 50 times](_URL_1_). That said, most species on Earth don't have brains, hearts or eyes, but are unicellular. Multicellularity took a long time to arise on Earth, so we might expect that most alien lifeforms would be unicellular as well.", "topk_rank": 2 }, { "id": "corpus-293534", "score": 0.7199856042861938, "text": "Yes. See [Last universal common ancestor](_URL_0_). Yes, even methane-metabolizing bacteria. That Wikipedia page also outlines the evidence in favor of this. However, this does not mean that life didn't spring up in a common way in separate places or times. All it means that the life present today that we have researched so far has a common ancestor; other lineages might be extinct or undiscovered.", "topk_rank": 3 }, { "id": "corpus-298568", "score": 0.7193014621734619, "text": "In the case of spiders and scorpions, they came from the same ancestor, they're both arachnids. But that's not true for every animal that looks like another animal. Two completely different species can evolve the same features in convergent evolution.", "topk_rank": 4 }, { "id": "corpus-241525", "score": 0.7190287709236145, "text": "You will really love this article: [Uprooting the Tree of Life](_URL_1_). Basically, horizontal gene transfer was absolutely rampant in the early history of life, so if anything the tree of life springs from more of a vague genetic morass than a single universal common ancestor. And it's not just the early history, either. For instance, genes have been known to jump between the ancestors of certain [cows and snakes](_URL_0_), presumably carried around by blood-sucking ticks (I'm not sure exactly what the mechanism is that put the genes from the blood carried by the tick into the new host's nuclei. I know retroviruses do that, but they're not mentioned here.) As I understand it, this is mainstream science among biologists and the picture of a tree of life with a single point of origin and clean lines of genetic descent is basically a pedagogical simplification.", "topk_rank": 5 }, { "id": "corpus-110492", "score": 0.7179747223854065, "text": "First, by most measures, we don't share anywhere near 99% of our DNA with trees. The typical figure thrown about is 60% commonality between humans and banana plants, for instance; the number would probably be somewhere in that vicinity for most species of tree. That said, there's a whole lot of shared functionality between various kinds of living organisms, so they do share a whole lot of their DNA. Things like cell respiration, DNA replication, cell nuclei structure, and protein synthesis are all things both plants and animals have to do, and they share the DNA for some number of them. You can think of it like the difference between a (wooden) bridge and a (wooden) house. They look super different and are used in different ways, and nobody would confuse one for the other, but no matter which one you're building you need timber, nails, load-bearing beams, flat sheets that things can rest on, etc.", "topk_rank": 6 }, { "id": "corpus-121776", "score": 0.7178620100021362, "text": "Yes, all humans are descended from a common human population. Furthermore, all life on Earth is related by common descent. Go far enough back and your lineage merges with that of cows, or clams, or trees, or mushrooms.", "topk_rank": 7 }, { "id": "corpus-254510", "score": 0.7177133560180664, "text": "I think it's important to note that we don't just share a common human ancestor. We have a common ancestor with chimpanzees. All vertebrae share a common ancestor, as do all mammals, etc... Groups of species with a common ancestor are known as a [clade](_URL_3_) and can be represented using a [phylogenetic tree](_URL_5_). This is a fundamental concept in evolutionary biology. It is also key to understand that we can't clearly define the first human. The [classic diagram](_URL_1_) you see of evolution is inaccurate. Evolution isn't linear. Rather it is many small changes over huge amounts of time. This is very well shown using [this image](_URL_4_). That being said, the common matrilineal ancestor is known as the [Mitochondrial Eve](_URL_2_) and the most common patrilineal ancestor is [Y-chromosomal Adam](_URL_0_).", "topk_rank": 8 }, { "id": "corpus-145419", "score": 0.7175832986831665, "text": "As far as we know, yes. All the information we have points to a common ancestor for every living creature on the planet, referred to as LUA (Last Universal Ancestor). As all life appears to be able to be traced back to one source, everything currently living is very, very distantly related. To the point that it's kind of a stretch to consider everything your cousin, but strictly speaking, it's true.", "topk_rank": 9 }, { "id": "corpus-240829", "score": 0.7153276205062866, "text": "All plants are related through one common ancestor. Both are land plants that have vascular systems and both are angiosperms but other than that they are not closely related. Corn is a monocot grass native to central America while jackfruit is a eudicot native to India.", "topk_rank": 10 }, { "id": "corpus-240329", "score": 0.7130867838859558, "text": "Yes. When describing other species anatomy there is a corresponding naming scheme for their body parts. All vertebrates share the same basic blue print, so in this case both we and a cow and a dog have an ulna. There are description of species-specific differences, whales lacking the second pair of limbs for example. And there is a scientific naming system for arthropod and other invertebrate anatomy. Science wouldn't work if we couldn't properly specify what we're talking about.", "topk_rank": 11 }, { "id": "corpus-187885", "score": 0.7128502130508423, "text": "Fruit came after animals. When dinosaurs started walking the earth there was no grass or trees evolved yet. We think of plants as being evolved first, but modern plants are fairly new", "topk_rank": 12 }, { "id": "corpus-43851", "score": 0.7123487591743469, "text": "Because these animals all are descendants of a common ancestor that had similar organs as well. Most animal eyes are very different from human eyes but they do share many common features. These common features were inherited from ancestors that had those features but lacked the specializations that present day animals gained (or had some specializations that were instead lost by some descendants).", "topk_rank": 13 }, { "id": "corpus-644301", "score": 0.70977383852005, "text": "**TLDR - Why are human/animal anatomies so similar?**\n\nDogs, cats, horses, humans, etc. all have bones, livers, lungs, hearts, etc. \n\n\nDoesn't evolution say that mutations happen by chance, and that any useful adaptations happen not because of direct adaptation to a climate, but rather through eons of life and death, with the most favorable genetic traits thriving and surviving by chance mutation? \n\n\nI understand that the uses of a liver, bone/cartilage, heart, lungs, etc. are all, obviously, needed for our lives... but why is it that they're almost all essential for every life form that exists? Why do so many species overlap with having extremely similar physiology to one another? \n\nAlso, and I know this is going to sound incredibly dumb but bear with me - Trees are alive, and they've been around dating back to the earliest periods that Earth could harbor life. So why didn't we see (again, I know this probably sounds dumb) Ent-like creatures develop over time, with a completely different physiology but the capacity to function \"intelligently\" as other life forms do?", "topk_rank": 14 }, { "id": "corpus-305459", "score": 0.7088768482208252, "text": "It is impossible to really predict the outcome of evolution, and when you say evolve you're looking at so many years down the road it's hard to tell. Basically anything COULD happen, although plants are so specialized right now that it would be unlikely for them to develop animal characteristics. I would think that would also mean they would somehow have lost their chloroplasts somewhere down the road, and considering how important they are in photosynthesis it is incredibly unlikely that a plant's environment would select against having a chloroplast. When animals and plants first diverged back when the first organic molecules started forming, and cyanobacteria began to be incorporated in living cells, we saw the distinction between plants and animals begin. It would be surprising to see that change. I'm no expert but that's just taking some things I've learned and incorporating them, if my science is incorrect anyone feel free to correct me.", "topk_rank": 15 }, { "id": "corpus-305189", "score": 0.7066817879676819, "text": "Birds are dinosaurs. The following statement is true for dinosaurs and birds: All dinosaurs share more recent common ancestors than any dinosaur and any reptile. > I realize yahoo answers is not science It's bad science. It is awful. There is not smooth transition between animal classes, nor is there a progression from fish to reptiles.", "topk_rank": 16 }, { "id": "corpus-320334", "score": 0.706321120262146, "text": "No. It would be some sort of bacteria or archaea (prokaryote superkingdom) where our closest common ancestor dates back to when a small prokaryote attacked a large prokaryote and got stuck inside leading to eukaryotes which eventually (2 billion years later) led to both bananas and humans.", "topk_rank": 17 }, { "id": "corpus-79458", "score": 0.7062925696372986, "text": "Those types of animals evolved from common ancestors, and fit their niches. However, not all animals (snakes, fish, etc) are like that. Its a matter of the common ancestor being (relatively) recent enough.", "topk_rank": 18 }, { "id": "corpus-260094", "score": 0.7062689661979675, "text": "No. Not the same. Convergent evolution results in similar organisms occupying the same niche, but they will not be the same.", "topk_rank": 19 } ]

[ { "id": "corpus-325398", "score": 0.7750092148780823, "text": "Short answer: Yes! Long answer: Actually plant life isn't that different from animal life when you look at it on a molecular basis. As plants are eukaryonts (their cells have a nucleus) they are even more closely related to us than for example bacteria. Their DNA resembles ours in many ways and even codes for some of the same proteins. This is most probably due to a common ancestry. Concerning the origin of life... there is no evidence that life on earth started more than once, all living things most certainly share a common ancestor and lines split only after evolution kicked in (as evolution could only start AFTER life had begun)." } ]

[ { "id": "corpus-305587", "score": 0.7333145141601562, "text": "That's more of a philosophy question than science - it simply depends on how you view that common ancestry. Also, trace the ancestry back even further and we shared a common ancestor with plants as well - so by your argument, eating anything living at all would be cannibalism. Just some proverbial food for thought...", "topk_rank": 0 }, { "id": "corpus-295896", "score": 0.7325794100761414, "text": "Yes and no. [Carnivora](_URL_0_) is a monophyletic order of placental mammals. So that's the yes. Most of the carnivores share a common ancestor. The no is that some species of cetaceans (whales and dolphins) also eat meat, but they aren't from that order. Note: I treated insectivores as separate from carnivores. Second note: the latter phenomenon you were talking about, where traits evolve to be similar because those are the most efficient (i.e. sharks and dolphins have similar looking bodies) is called convergent evolution.", "topk_rank": 1 }, { "id": "corpus-307284", "score": 0.7288830876350403, "text": "Yes, all life is believed to be derived from a common ancestor [(Source)]( _URL_2_). We often sort organisms by their relatedness to make a [“tree of life” called a phylogeny](_URL_0_). However, life *may* have originated multiple times, but all but one type of life died out due to selection leaving all known organisms with a single ancestor [(Source)]( _URL_1_).", "topk_rank": 2 }, { "id": "corpus-127676", "score": 0.7265849709510803, "text": "No, while we share a common ancestor, our evolution went a different direction to apes. [This](_URL_0_) gives you an idea.", "topk_rank": 3 }, { "id": "corpus-277397", "score": 0.7263439893722534, "text": "I'm not familiar enough with this to speak for all animals, but there are two relevant common human ancestors (because of sexual reproduction): [Mitochondrial Eve](_URL_1_) and [Y-chromosomal Adam](_URL_0_).", "topk_rank": 4 }, { "id": "corpus-316530", "score": 0.7249919176101685, "text": "While I can't answer which came first, I can tell you that all life on this planet seems to share an ancestry at least at some point. Here's some previous discussions on the topic: _URL_0_ _URL_2_ _URL_1_", "topk_rank": 5 }, { "id": "corpus-285560", "score": 0.724810779094696, "text": "How much uncertainty are we talking about here? At least in plants, we don’t have very good resolution on *most* branches of the tree of life once you get down to species level, and even genus level is pretty fuzzy in some families. I can’t speak to animals, though, and they tend to lack the weirdass reproductive options that blur a lot of plant lineages.", "topk_rank": 6 }, { "id": "corpus-266871", "score": 0.7247219085693359, "text": "Humans and chickens are on the same evolutionary tree. We share a common ancestor with chickens that already had single bones in their upper limbs and double bones in their lower limbs. This is called homology, anatomical identity by descent. Organisms that evolve anatomical traits independently generally do it in different ways. For example birds and bats evolved their wings independently, meaning they did not inherit their wings from a common ancestor that had wings. So even though their wings are both modifications of the front limbs (made up of the humerus, radius, ulna, and carpals since their common ancestor did have front limbs made up of these bones), the modifications that make those bones into wings are entirely different. This is called analogy, convergent function but non-identical descent.", "topk_rank": 7 }, { "id": "corpus-319932", "score": 0.7245866656303406, "text": "Yes, all life appears to have come from 1 abiogenetic event - or if not, several incredibly similar events producing incredibly similar organisms along the same lines (i.e. carbon-based with nucleic acids as the coding component). Given that the hypothesis for creating such life would require lightning to strike a pool with a clay-like bottom it's entirely possible that it happened in multiple places, we just can't be sure either way. The point is though that this event would produce a common ancestor which could lead to the evolution of both plants and animals (and probably did).", "topk_rank": 8 }, { "id": "corpus-128744", "score": 0.7239868640899658, "text": "All domestic dogs are the same species, and are pretty nearly identical genetically. This is far from the case with birds. Two bird species taken at random might have last had a common ancestor millions of years ago, making them as closely related as humans and howler monkeys. Dogs all share such an ancestor only about 10 000 years ago.", "topk_rank": 9 }, { "id": "corpus-283536", "score": 0.7217223644256592, "text": "I think this question is making some assumptions about evolution that I'm not so much a fan of. Plants have evolved over a really long period of time (longer than any animal) to be really good at what they do. Assuming that evolution eventually leads to sentience sapience or animal form is pretty determinist. It sort of follows from that logic that the trajectory of all evolution is toward animals. This isn't the case, evolution isn't linear. There is no \"hierarchy of organisms\". Plants fill a separate ecological niche than animals and there's pretty much no reason for them to start behaving like another kingdom. If plants eventually evolved sentience and started moving around, they'd probably do it in a radically different way than animals do because they posses a pretty disparate genetic toolkit to the animal kingdom.", "topk_rank": 10 }, { "id": "corpus-257505", "score": 0.721367359161377, "text": "Monotremes (the Platypus and the Echidna are the only examples I know of) shared a common ancestor with other mammals about 160 million years ago. We can call them our extremely distant cousins (actually, the most distant mammal cousin).", "topk_rank": 11 }, { "id": "corpus-254689", "score": 0.7201359272003174, "text": "All species have a common ancestor, but that ancestor did not have a brain, heart or true eyes. Brains have evolved in animals at least [9 times](_URL_0_). Eyespots evolved independently [around 50 times](_URL_1_). That said, most species on Earth don't have brains, hearts or eyes, but are unicellular. Multicellularity took a long time to arise on Earth, so we might expect that most alien lifeforms would be unicellular as well.", "topk_rank": 12 }, { "id": "corpus-293534", "score": 0.7199856042861938, "text": "Yes. See [Last universal common ancestor](_URL_0_). Yes, even methane-metabolizing bacteria. That Wikipedia page also outlines the evidence in favor of this. However, this does not mean that life didn't spring up in a common way in separate places or times. All it means that the life present today that we have researched so far has a common ancestor; other lineages might be extinct or undiscovered.", "topk_rank": 13 }, { "id": "corpus-298568", "score": 0.7193014621734619, "text": "In the case of spiders and scorpions, they came from the same ancestor, they're both arachnids. But that's not true for every animal that looks like another animal. Two completely different species can evolve the same features in convergent evolution.", "topk_rank": 14 }, { "id": "corpus-241525", "score": 0.7190287709236145, "text": "You will really love this article: [Uprooting the Tree of Life](_URL_1_). Basically, horizontal gene transfer was absolutely rampant in the early history of life, so if anything the tree of life springs from more of a vague genetic morass than a single universal common ancestor. And it's not just the early history, either. For instance, genes have been known to jump between the ancestors of certain [cows and snakes](_URL_0_), presumably carried around by blood-sucking ticks (I'm not sure exactly what the mechanism is that put the genes from the blood carried by the tick into the new host's nuclei. I know retroviruses do that, but they're not mentioned here.) As I understand it, this is mainstream science among biologists and the picture of a tree of life with a single point of origin and clean lines of genetic descent is basically a pedagogical simplification.", "topk_rank": 15 }, { "id": "corpus-110492", "score": 0.7179747223854065, "text": "First, by most measures, we don't share anywhere near 99% of our DNA with trees. The typical figure thrown about is 60% commonality between humans and banana plants, for instance; the number would probably be somewhere in that vicinity for most species of tree. That said, there's a whole lot of shared functionality between various kinds of living organisms, so they do share a whole lot of their DNA. Things like cell respiration, DNA replication, cell nuclei structure, and protein synthesis are all things both plants and animals have to do, and they share the DNA for some number of them. You can think of it like the difference between a (wooden) bridge and a (wooden) house. They look super different and are used in different ways, and nobody would confuse one for the other, but no matter which one you're building you need timber, nails, load-bearing beams, flat sheets that things can rest on, etc.", "topk_rank": 16 }, { "id": "corpus-121776", "score": 0.7178620100021362, "text": "Yes, all humans are descended from a common human population. Furthermore, all life on Earth is related by common descent. Go far enough back and your lineage merges with that of cows, or clams, or trees, or mushrooms.", "topk_rank": 17 }, { "id": "corpus-254510", "score": 0.7177133560180664, "text": "I think it's important to note that we don't just share a common human ancestor. We have a common ancestor with chimpanzees. All vertebrae share a common ancestor, as do all mammals, etc... Groups of species with a common ancestor are known as a [clade](_URL_3_) and can be represented using a [phylogenetic tree](_URL_5_). This is a fundamental concept in evolutionary biology. It is also key to understand that we can't clearly define the first human. The [classic diagram](_URL_1_) you see of evolution is inaccurate. Evolution isn't linear. Rather it is many small changes over huge amounts of time. This is very well shown using [this image](_URL_4_). That being said, the common matrilineal ancestor is known as the [Mitochondrial Eve](_URL_2_) and the most common patrilineal ancestor is [Y-chromosomal Adam](_URL_0_).", "topk_rank": 18 }, { "id": "corpus-145419", "score": 0.7175832986831665, "text": "As far as we know, yes. All the information we have points to a common ancestor for every living creature on the planet, referred to as LUA (Last Universal Ancestor). As all life appears to be able to be traced back to one source, everything currently living is very, very distantly related. To the point that it's kind of a stretch to consider everything your cousin, but strictly speaking, it's true.", "topk_rank": 19 } ]

[ { "id": "corpus-325399", "score": 0.7976594567298889, "text": "I can think of at least one thing that would affect the reflection off a mirror moving at high lateral speeds, though there are probably more. There is some (very short) time delay between when the mirror absorbs incident light and when the mirror re-emits the the incident light. This is because whenever light falls onto the surface of a conductor, it doesn't just interact with the surface, it interacts with all the atoms near the surface to a depth roughly equal to the skin depth of the metal, which is usually a few nanometers, or a few hundred atomic radii. This gives the reflected beam a very tiny lag, of something like 10^-18 seconds. This means the reflection would probably be dragged along the direction of motion by a very small amount." } ]

[ { "id": "corpus-324191", "score": 0.7576731443405151, "text": "The number of photons emitted - what you perceive as \"light\" - would be unchanged. The mirror would only distribute them differently. So the perceived increase in brightness from the reflection in the mirror is offset by the shadow the mirror casts.", "topk_rank": 0 }, { "id": "corpus-835301", "score": 0.7574090957641602, "text": "Being that the mirror would be on the inside and the see through side would be outside, what is expected to be seen?\nAre there any theses done to predict such an effect?\nHow much would it vary depending on the light source or object?\n(Saw the one way mirror cube post and this came to mind... probably gonna get ignored tho)", "topk_rank": 1 }, { "id": "corpus-145584", "score": 0.7568824291229248, "text": "_URL_0_ See this image? If the mirror is placed at the point where the light bounces off the wall, you will be able to see the reflection of the object. It doesn't matter if the mirror only extends a foot in either direction as long as it's in that spot.", "topk_rank": 2 }, { "id": "corpus-178315", "score": 0.756636381149292, "text": "If you are not referring to the \"white body\" term that is used in physics and you only mean a real white object like white colored wall or something, the answer is very simple. Mirrors reflect light in a straight line, while white objects diffuse the light in any possible direction. Even if the same intensity of light reaches your eye (which is unlikely, but for the argument let's go with it) you don't see the reflected light like one in the mirror. Think about the light being a picture. If you see it in the mirror, you see exactly that picture. If you look at a white object, you see the same picture, but every Pixel is randomly rearranged.", "topk_rank": 3 }, { "id": "corpus-316474", "score": 0.756626546382904, "text": "No. Since mirrors don't reflect 100% of the light that hits them, eventually the light will have bounced back and forth so much that all of it has been absorbed. Even with theoretically perfect mirrors, there is a point at which the wavelength of visible light does not allow features of a certain size to be resolved, which is why we use things like electron microscopy for very small objects. Since each successive mirror image is smaller than the last, you will reach a point where the size of the image is smaller than what visible light can resolve, and it's just noise.", "topk_rank": 4 }, { "id": "corpus-311152", "score": 0.7556518316268921, "text": "It’s because the direction of reflection isn’t preserved. White surfaces can be explained by light penetrating into the surface, scattering, and then exiting the surface in a random direction. With a mirror, there is no penetration and the incident angle is equal to the reflected angle.", "topk_rank": 5 }, { "id": "corpus-286740", "score": 0.7555442452430725, "text": "Any flat mirror should give you an accurate image, this is because on a flat mirror, the rays are all treated the same.", "topk_rank": 6 }, { "id": "corpus-320399", "score": 0.7550646662712097, "text": "Regular mirrors are made to reflect visible light. Other types of electromagnetic radiation may not be reflected. For example, small waves like x-rays and gammas will pass right through a normal mirror.", "topk_rank": 7 }, { "id": "corpus-292919", "score": 0.7545492053031921, "text": "In an idealized case, no difference. The only difference between a mirror and \"white\" is the *direction* that the light is reflected. The amount of absorption is the same. In practice, the mirrored one would stay cooler. This is because practical whites are less reflective than high-quality mirrors; part of reflecting light in random directions is that sometimes they reflect light inward and absorb it. Also, mirrored surfaces usually reflect non-visible wavelengths well. White diffusers more commonly have a limited range of effective frequencies.", "topk_rank": 8 }, { "id": "corpus-312629", "score": 0.7545203566551208, "text": "You are correct, but are a few practical matters that intrude on this. First, mirrors are not 100% reflective. After 500 reflections, less than 1% of the light is left. That might sound like a lot, but if your mirrors are a meter apart, that takes a little more than a millionth of a second. Then you got alignment. If the mirrors are 1^o off, the first reflection will be 1^o off, the second 2^o, the third 4^o, and so on. For that 500^th reflection to be on target, you would need alignment on the subsubatomic scale and beyond. Finally, you have the Dawes limit. Because light is a wave, diffraction introduces a level of blurriness, even with perfect optics. With a 1m mirror, the Dawes limit would be reached at about 500m, or 500 reflection if the mirrors were 1m apart.", "topk_rank": 9 }, { "id": "corpus-96289", "score": 0.7542034387588501, "text": "Because the mirror actually doesn't reverse left right. It reverses _front and back_ - as if someone pulled your nose out the back of your head. If you track the image from the wall behind you, you'll notice that your back is closer to that wall than your nose is. However, if you extend this analysis to your image, you'll see that the nose of your image is closer to the (real) wall behind you than the back of your image. You've reflected front and back.", "topk_rank": 10 }, { "id": "corpus-131874", "score": 0.7536590099334717, "text": "Actually, the reflected image of the TV is 10+1 feet away. The mirror does not \"reset\" the reflected image of the TV to a distance of one foot, the light rays from the TV behave, from your POV, as if they originated from a point 10 feet *behind* the mirror.", "topk_rank": 11 }, { "id": "corpus-171862", "score": 0.7535092234611511, "text": "Assuming that mirrors are at a 90 degree angle the light reflected from your body will always make a 180 degree turn. Light reflects at the same angle as it falls. So let's say a ray of light falls on a mirror at an angle of 60 degrees. Then it will bounce back at an angle of 60 degrees and fall on a second mirror at an angle of 30 degrees and bounce again at 30 degrees. That gives us 180 combined.", "topk_rank": 12 }, { "id": "corpus-321979", "score": 0.753466784954071, "text": "The mirror is not flipping along the vertical axis, but instead in the front/back axis. You can see this by noting that if you point your hand out toward the mirror the reflection of your hand appears to be getting closer (movement away is changed to movement toward). You don't usually see people flipped front/back, so you perceive the person of your reflection as having their left and right sides swapped.", "topk_rank": 13 }, { "id": "corpus-321813", "score": 0.7531726360321045, "text": "Mirrors actually reflect at all angles, it's the interference of the light waves that cause them to rebound like they do. If you think of the light as a wave moving in all directions from a point, you can see that if it hits a boundary it will bounce off. The way it does that is to have each point on the mirror act as its own light source ([huygens-fresnel principle](_URL_1_)) and the interference of light from all those points is what causes the wave to reflect as it does. A surface could be retro-reflecive if instead of being flat it were made of a bunch of tiny [corner reflectors](_URL_0_). if you want to get an excellent understanding of light you should read *QED: The Strange Theory of Light and Matter* by Richard Feynman", "topk_rank": 14 }, { "id": "corpus-45538", "score": 0.7529464960098267, "text": "There are actually two mirrors in your rearview. The first one reflects a lot of light and the second one reflects less. That's why your rearview mirror isn't perfect flat, it's more wedge-shaped to fit both mirrors. When you hit that switch it moves the second mirror into place.", "topk_rank": 15 }, { "id": "corpus-289953", "score": 0.7524086236953735, "text": "No mirror is perfectly reflective, a small amount of light is lost with each reflection. Eventually the image decays.", "topk_rank": 16 }, { "id": "corpus-259067", "score": 0.7523970007896423, "text": "They would be about the same; a polished sheet and a sheet painted white both reflected all wavelengths of light. They just do it in different ways - the paint reflects light diffusely, causing all the light waves to interfere into plain white, while the 'mirror' reflects to form an image. Neither absorbs very much light, but I would suspect that the paint be a bit less reflective, in all.", "topk_rank": 17 }, { "id": "corpus-292493", "score": 0.7523544430732727, "text": "Yes, it involves an aptly named [non-reversing mirror](_URL_1_), in which you have some kind of \"curved\" surface to reflect the light. The most common one is the two pieces of glass put together but the third one listed looks like [this](_URL_0_), which is still curved in some way, but pretty cool.", "topk_rank": 18 }, { "id": "corpus-85234", "score": 0.7522579431533813, "text": "When you say the image is all in the same plane, you're probably thinking of a mirror as being in some way similar to a television or computer monitor. That's not the case -- a monitor or television produces its own picture by **emitting** light, whereas a mirror is merely a device for **reflecting** light that originates somewhere else. That means that when you're looking at your wife's reflection when she's standing 6 feet beind the mirror, the light from her face is travelling all the way to the mirror. It then reflects off and travels a further couple of inches to your eyes. So in total the light has travelled 6 feet + a few inches, and as far as your eye's lens is concerned it's the same as looking at your wife standing that distance away.", "topk_rank": 19 } ]

[ { "id": "corpus-325400", "score": 0.6439516544342041, "text": "they go up a few thousand feet and pop as the gas in the balloon expands beyond the stretching limit for the rubber. No balloon will ever make it into orbit.. orbit requires thousands and thousands of miles an hour of lateral velocity" } ]

[ { "id": "corpus-310376", "score": 0.6113395690917969, "text": "\"Vacuum airships would theoretically replace the helium gas with a near-vacuum environment and would theoretically be able to provide the full lift potential of displaced air. The main problem with the concept of vacuum airships however is that with a near-vacuum inside the airbag, the outside pressure would exert enormous forces on the airbag and causing it to collapse if not supported. Though it is possible to reinforce the airbag with an internal structure, it is theorized that any structure strong enough to withstand the forces would invariably weigh the vacuum airship down and exceed the total lift capacity of the airship, preventing flight.\" _URL_0_", "topk_rank": 0 }, { "id": "corpus-276952", "score": 0.6111517548561096, "text": "It's not *escaping* Earth (well, it is, but that's not really the issue). It's that all of our easily accessible sources are being used up. Essentially, a U.S. law has made helium cheaper than it should be by flooding the market, paying no regard to demand. So all of those party balloons are popping and the Helium is buggering off into the atmosphere where it's too hard to get at it. On top of that, there's no incentive to recycle the helium we *can* reprocess and reuse. It's just being treated as waste. Mostly, we get our helium from underground deposits. It's a by-product of the extraction of natural gas. There's no other financially viable way to get the stuff. Edit: Amusing little tidbit from my googling: Apparently, the bit of helium that does remain in the atmosphere is used as \"evidence\" to support Young Earth Creationism. Okie dokie then....", "topk_rank": 1 }, { "id": "corpus-182464", "score": 0.6109621524810791, "text": "Helium is one of the least abundant gasses in our atmosphere. It is not a renewable resource. Also, it is not captured from the atmosphere, it is found in mines in the earth. Once it is released into the atmosphere it is essentially “lost” and not ever recovered.", "topk_rank": 2 }, { "id": "corpus-322137", "score": 0.6109181642532349, "text": "The other answers are correct but didn't answer your actual question: if you had a magical material that wouldn't allow any helium to diffuse out, then yes, the balloon would float forever.", "topk_rank": 3 }, { "id": "corpus-284019", "score": 0.6107888221740723, "text": "When you say it is tightly secured with no leaks, you are ignoring the gaps between the latex molecules. These vary in size, and a few are larger than air molecules. More of the holes are larger than Helium atoms, which is why Helium balloons deflate faster than air balloons (which in turn deflate faster than a balloon filled with, say, Sulfur Hexafluoride would).", "topk_rank": 4 }, { "id": "corpus-319230", "score": 0.6101902723312378, "text": "Yes. If we assume a balloon which doesn't compress the gas inside it (probably a fairly reasonable assumption) we can easily work out the volume of helium required. Assume the mass of the deflated balloon is 5 g or 0.005 kg. The effective mass (the reading that would show on scales if you were to weigh the balloon) is given by, m = 0.005 + V( ρ - ρ' ) where V is the volume of the balloon, ρ is the density of helium and ρ' is the density of air. If we want the effective mass to be 0 then we can solve for V: V = 0.005 / ( ρ' - ρ ) Density of air at sea level and 15 C is ρ' = 1.225 kg/m^3 Density of helium at sea level and 15 C is ρ = 0.169 kg/m^3 so V = 0.00473 m^3 or 4.73 Litres Since a real balloon exerts some pressure on the gas inside it, an experimentally determined value would probably be a little higher (since the density of the helium in the balloon would be slightly higher). Sources: [Density of air](_URL_0_) [Density of helium](_URL_1_)", "topk_rank": 5 }, { "id": "corpus-319551", "score": 0.6101271510124207, "text": "So far, Helium has been mostly recuperated as a by-product of natural gas operations. The reason is that pretty much all terrestrial Helium is the product of nuclear disintegration of radioactive isotopes deep within the Earth. This Helium slowly accumulates and concentrated in natural gas reservoirs, where it found in solution. Since the Helium is in solution in the gas, it is recuperated alongside the gas during reservoir production. It may be separated from the gas during the purification/liquefaction process, by separating it through fractional distillation. See: _URL_1_ That being said, the information above may be less accurate than it used to, as [straight Helium deposits (without natural gas) have begun to be sought out, and found](_URL_0_), notably along the East-African Rift. Whether it will be possible to put these new deposit types hosted by volcanic successions into commercial production in an economically sustainable way remains to be seen, but it sure is an interesting development.", "topk_rank": 6 }, { "id": "corpus-192381", "score": 0.6090106964111328, "text": "For things like rubber balloons, the material is like 99.9% impervious to gases like helium, but not 100% so over time it just very slowly leaks through.", "topk_rank": 7 }, { "id": "corpus-67863", "score": 0.6076090931892395, "text": "Air is pressurized inside the balloon. When the balloon pops, it releases that air very rapidly...your ears hear that expanding air as a \"pop\". The higher the air pressure inside (e.g. new balloon inflated to maximum size), the louder the pop when it breaks. Only a small amount of noise is caused by the actual rubber/plastic breaking, most of it is just air pressure.", "topk_rank": 8 }, { "id": "corpus-165102", "score": 0.6070368885993958, "text": "Much like \"peak oil\", the world will likely never completely run out of helium - it will merely become too expensive for most to afford. Beyond balloons and dirigibles/blimps, helium is an incredibly important mechanism for cooling large machines, especially magnetic ones, like particle accelerators (the LHC) and MRI and other medical imaging machines. On the bright side, if we ever figure out fusion, hydrogen is easy to get and the common fusion reactions produce helium.", "topk_rank": 9 }, { "id": "corpus-129388", "score": 0.6070247888565063, "text": "The smaller balloon has a higher internal pressure. The inward tension from the balloon rubber decreases as the diameter of the balloon increases. i.e. the bigger it is, the easier it gets to inflate it a bit more. So the air flows from the higher pressure (small balloon) to the lower pressure (large balloon). Think about it a slightly different way. If you blow up a balloon and let it go what happens? The higher pressure (balloon) goes into the lower pressure (the room). The room could be considered a much bigger balloon...", "topk_rank": 10 }, { "id": "corpus-188079", "score": 0.606943666934967, "text": "We can't produce helium unfortunately, but we can separate it from natural gas deposits. Pumping it into tanks is a basically just a process of pushing a lot of in harder than it's trying to escape, so that you can stuff a large quantity in a small, cramped (pressurized) space.", "topk_rank": 11 }, { "id": "corpus-176846", "score": 0.6068703532218933, "text": "Compressed helium is heavier than air, it's only when allowed to expand inside a container to near atmospheric pressure does bouyancy come into play", "topk_rank": 12 }, { "id": "corpus-324382", "score": 0.6066693067550659, "text": "Nope. Even the world's best vacuum systems will, in general, leak a bit of helium. Its simply too small, light and non-reactive to be contained by most materials. I have spent many hours trying to bring down my helium peak in high vacuum experiments.", "topk_rank": 13 }, { "id": "corpus-257221", "score": 0.6062147617340088, "text": "Helium and air have densities of around 0.18kg/m^3 and 1.28kg/m^3 respectively at STP. This means that each cubic metre of helium can support almost 1.1kg (1.275-0.179kg) under these conditions. A high vacuum, on the other hand, has a density of 0kg/m^3 meaning it can support around 1.3kg per cubic metre. This means a decent vacuum can only support about an additional 16% in comparison to helium. This means the structure required to contain your vacuum can only be 16% heavier than that used for helium to provide equivalent lift for a given size balloon. So yes, a vacuum will produce a buoyant force, but the gains are minimal compared to helium or hydrogen!", "topk_rank": 14 }, { "id": "corpus-317334", "score": 0.6060351729393005, "text": "Most commercially used helium is produced through fractional distillation of Natural Gas. Helium has a distinct boiling point from the other components of natural gas and therefore can be separated by boiling the helium out of natural gas. Helium is only present in minute fractions in air so reclaiming it from air is difficult and costly", "topk_rank": 15 }, { "id": "corpus-313819", "score": 0.6059248447418213, "text": "The mass of a helium balloon is positive. The weight is negative. There might be such a thing as negative mass, but we haven't encountered such a thing yet.", "topk_rank": 16 }, { "id": "corpus-868288", "score": 0.605853259563446, "text": "What would happen if you put a balloon in your vagina and blew it up while it was there", "topk_rank": 17 }, { "id": "corpus-297748", "score": 0.6051881313323975, "text": "As the balloon rises the outside pressure drops causing the balloon to expand, eventually the balloon either bursts or obtains neutral buoyancy. Also, it sounds like both parts of your problem- make it stay in sight and come down rather quickly could be obtained by having a very slight air leak.", "topk_rank": 18 }, { "id": "corpus-850122", "score": 0.6039755344390869, "text": "Do you know/think it's allowed to bring small Helium tanks into the camping grounds? We are thinking about decorating our camp :D", "topk_rank": 19 } ]

[ { "id": "corpus-325401", "score": 0.7314661741256714, "text": "Partially right. It's mainly erosion, and many smaller things are lost due to disintegration in the atmosphere. Water, wind, ice, etc- they all work to reform the landscape, erasing evidence of impacts. But we still see plenty of craters in dry places or places with less erosional activity. Meteor crater in Arizona is a good example. Also, impacts in the ocean are much less likely to leave a crater (unless it's really big), and since oceans cover over half the surface area of the earth, that many less craters!" } ]

[ { "id": "corpus-238123", "score": 0.6948557496070862, "text": "There was a recent paper by Yu and Jacobsen that has a nice diagram of how Earth accreted but basically the first 10% of the mass or so comes from frequent small collisions in a stage called planetesimal formation (think km sized objects or so). However, the bulk of the mass comes from 5-10 giant impacts (something about the size of mars). The last 10% then comes from the moon forming impact which happened sometime after the rest of accretion slowed down. It depends on which images you are talking about the ones that show the moon forming impact with a glowing red Earth (or worse one covered in magma) is probably incorrect but accretion of large objects is a violent process. It should be noted that this entire process was probably finished within 10 million years or so (except for the moon forming impact). That might be slow on a human scale (5-10 mars sized impactors over 10 million years or 0.5-1 per million years) but on a geologic scale that is essentially instantaneous.", "topk_rank": 0 }, { "id": "corpus-75366", "score": 0.6947853565216064, "text": "basically... the soil on the moon is called regolith... and it reflects light. just like silver reflects light way better than titanium does :) edit: Albedo is how well an object reflects light, the moons albedo is higher than earths is 2# edit: fact check", "topk_rank": 1 }, { "id": "corpus-1169751", "score": 0.693686306476593, "text": "If it was completely crater-free, it was probably for a very short period right after it was first formed. I also wonder how strange a craterless full moon would appear in the night sky. I mean, would it look that different to the naked eye?", "topk_rank": 2 }, { "id": "corpus-302323", "score": 0.6936450600624084, "text": "While most scientists believe that our only satellite was the product of Earth's collision with Theia, a mars-sized planet drifting through the young solar system, the moon is unlikely to crash into us. In fact, it is actually drifting away from us, by about an inch a year. But, if a moon-sized asteroid hit us, the blast wave would be huge, and would surely circumnavigate the globe; within 24 hours, the entire surface of Earth would be molten and/or on fire. No part would be spared. If a much smaller asteroid hit us, parts of the Earth would be not be scorched, but nonetheless, whatever lived in these intact areas would likely still die, due to the subsequent long freeze. This has happened, in various degrees of severity, about six times in Earth's history. There are some pretty cool simulations of it on Youtube. _URL_0_", "topk_rank": 3 }, { "id": "corpus-100280", "score": 0.6933922171592712, "text": "Because the moon is **really** far away and the moon lander is exponentially smaller. We didn't have a telescope with enough power to see something of that detail.", "topk_rank": 4 }, { "id": "corpus-323651", "score": 0.6917417645454407, "text": "Mostly because of the inclination of the moon to the Earth. The moon is inclined 5 degrees relative to the Earth and so rarely lines up with the sun. [A diagram.](_URL_0_)", "topk_rank": 5 }, { "id": "corpus-321151", "score": 0.6912597417831421, "text": "The crater would be about the same size as the one on earth (180km ish) although debris would have dispersed more widely. If pieces did approach Earth (and this would be strongly dependant on which side of the moon was it, from which direction, and at which point in the moons orbit), the majority will have burned up in the atmosphere. I would not have destroyed the moon - the moon is covered in craters which mark the remnants of similar or even larger impacts over its history. Its orbit will have changed slightly (as indeed our own will have done), but the amount is relatively negligible, and again dependent on the directions and velocities.", "topk_rank": 6 }, { "id": "corpus-314757", "score": 0.6910831332206726, "text": "So I might be talking about the wrong thing here, but the moon has certain areas we call Oceans/Seas, which would be the dark grey areas of the moon, the color contrast between these areas and the rest of the moon are due to the Oceans/Seas being basaltic planes (basically it was lava at some point), there are concentrated points in between these that are really lightly colored, those are mainly craters. Here's a good reference for all of that: _URL_0_ Hope that answers that!", "topk_rank": 7 }, { "id": "corpus-261575", "score": 0.691071629524231, "text": "First of all, the moon was most likely formed when a planet the size of Mars struck the Earth about 4 billion years ago (the meteorite you mention struck the Yucatan Peninsula about 66 million years ago). If that meteorite had struck the Earth in an easterly direction, it could have increased the rotational speed of the Earth, but the increase would have been very small. It had a mass between 10^15 and 10^17 kg. Compared to the Earth's mass of 10^24 kg, this would be like a small pea hitting a person.", "topk_rank": 8 }, { "id": "corpus-282131", "score": 0.6901867389678955, "text": "This answer is lacking as well, but is kind of helpful for some perspective if you know how big the moon is. All the water on planet Earth. Size comparison. _URL_0_", "topk_rank": 9 }, { "id": "corpus-169644", "score": 0.6901135444641113, "text": "The Earth is \"alive\" and the Moon isn't. Earth's got an atmosphere, water cycle, living things, and plate tectonics, each of which contribute to erosion and general smoothing of geological features. The Moon has some dirt on it. Nothing's going to move that dirt. There's no atmosphere to have wind blow it around, no water to wash it away in the rain", "topk_rank": 10 }, { "id": "corpus-320780", "score": 0.6894257664680481, "text": "iirc earth is the only planet in our solar system that has active plate tectonics. a good indicator are impact craters as plate tectonics constantly recycle crust which means that the majority of craters are quite 'recent' (in geological timescales). if you e.g. look at other planets or the moon you will see that the majority of craters are very old (late heavy bombardment etc.) and you have a lot of craters. the lack of tectonics is also the reason why mountains on mars can get so big - the surface does not move and hot spots effect only a specific spot (not like on earth where you have e.g. the hawaiian mountain chain) and the mountains kept growing. an exception is venus because it supposedly has undergone a resurfacing event \\~500 million years ago which erased evidence of old craters - but still does not show signs of tectonics", "topk_rank": 11 }, { "id": "corpus-319911", "score": 0.6893969774246216, "text": "The Moon actually isn't all that reflective. It has roughly the same albedo as asphalt, only reflecting about 12% of the total light that hits it. It's just that this 12% is actually rather a lot of light. Source: Open Uni Astronomy and Planetary Science student.", "topk_rank": 12 }, { "id": "corpus-78063", "score": 0.6893459558486938, "text": "The Moon is thought to have formed when a Mars-sized body impacted with the proto-Earth, with the resulting debris accreting to form the Moon. The gravitational tidal force of the Earth would then have pulled the Moon into an orbital plane along Earth's equator. However, the Sun also exerts a tidal force on the Moon, with the result being that the latter's orbit is tilted slightly (which is why we don't get a solar eclipse every new moon, and a lunar eclipse every full moon). Note that for most other bodies in the solar system, the orbital plane is determined not so much by tidal forces as the way they were formed. When the Sun formed, it was surrounded by a disc of gas and dust, which due to angular momentum tended to flatten out. It was out of this disc (called the accretion disk) that the planets and most of their moons formed, so they were already all on the same plane.", "topk_rank": 13 }, { "id": "corpus-316348", "score": 0.689324140548706, "text": "Depending on how far back in time you're thinking about, this question is pretty easy to answer. Because in the very early stages of the formation of our planet, it was struck by lots and lots of meteorites. In principle you could argue that Earth is mainly made build up from meteorites ( though it gets tricky with the definition of meteorites, which is roughly - according to wikipedia - \"[...] a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. \"). If you think of the more recent past, I can not really help you with your answer. But I hope somebody else with a little more knowledge will jump in.", "topk_rank": 14 }, { "id": "corpus-54141", "score": 0.6886977553367615, "text": "There are 2 main theories as to how the Moon formed. They both start with a Mars-sized object, dubbed Theai, colliding in a catastrophic manner with the Earth during the early formation of the Solar System. The first is generally referred to as [Great Impact Theory](_URL_1_), involves Theai impacting earth at a severe off-centered angle. What results is most of the matter being absorbed into the Earth and remnants of Theai being flung out and coalescing into the Moon. The second possibility is the [Accretion Theory](_URL_2_). It starts with Theai colliding pretty much dead-center with Proto-Earth, but instead of a large mass left over, almost all of the matter merges into the Earth and pushes loose debris out from the center to form an [Accretion Disc](_URL_0_) around the new planet. Then, over time, these orbiting debris clump together and form the moon.", "topk_rank": 15 }, { "id": "corpus-169829", "score": 0.6882235407829285, "text": "well, gravity is a bit like heat. The closer you are to something, the more you feel its effects. So the earth orbits the sun because of it's strength but the moon is just so close to earth that it's caught up in earth's gravity instead.", "topk_rank": 16 }, { "id": "corpus-33516", "score": 0.6880042552947998, "text": "Astronomers believe almost that very thing happened to the young Earth before it had a moon: it was hit by a Mars-sized body, which obliterated both, and the modern Earth/Moon system was born out of the debris. Such an event would have sterilized both bodies, if there had been anything living.", "topk_rank": 17 }, { "id": "corpus-324542", "score": 0.6875811815261841, "text": "There's essentially two types of moon - those that are captured asteroids, which are obvious - they tend to be similar to most other asteroids and are irregular in shape. The other kind, i.e. Io, Europa, Titan, are basically mini-planets (in some cases not so mini). We don't actually know how these formed. They could be captured planetesimals that formed at the same time as the planets. However, it's also possible they formed out of a kind of quasi-circumstellar disc around the planet - so like mini-solar system but with, say, Jupiter at the middle instead of the Sun.", "topk_rank": 18 }, { "id": "corpus-182569", "score": 0.6865503787994385, "text": "The Earth has a substantial atmosphere. The moon does not. Earth's atmosphere scatters sunlight as the light passes through it. This is what makes our sky bright and blue. The moon has no atmosphere to scatter light, so the sky is always dark and full of stars.", "topk_rank": 19 } ]

[ { "id": "corpus-325402", "score": 0.6691939234733582, "text": "I can think of a number of different reasons why this may be the case; metabolic rate change, drinking habits, alcohol tolerance just to name a few. But this is simply speculation. Here are a couple of studies that you might find interesting: [Age, alcohol metabolism and liver disease.](_URL_1_) [Variations in alcohol metabolism: influence of sex and age.](_URL_0_)" } ]

[ { "id": "corpus-2035940", "score": 0.6357020139694214, "text": "Sorry if this is a common question which has been answered before, but I haven't found much searching around.\n\nI have a type of social anxiety which seems a bit different than most, and I'd be interested in any thoughts or resources you might have about it.\n\nSo I'm a bit on the reserved side and not especially outgoing, but I don't have any social anxiety day to day, like talking to store clerks, that kind of stuff. And when I have a social event coming up (like a party or hanging out at the bar with a group of friends,) I'm fine there too. I look forward to it and don't worry about. \n\nAnd even during the social event, I enjoy myself, interact with people, and have a good time. All without any anxiety.\n\nBut if I had been drinking (even just a few drinks over the night,) when I wake up the next morning the anxiety is crushing. I spend hours tossing in bed worried about whether I said something weird, came off as a dick, touched somebody inappropriately (like if I touched someone's shoulder, what if they felt I was invading their space?) All kinds of worries. I just compulsively go over every little detail I can remember about the night, thinking about it in the worst possible light, and worrying that I seemed like an asshole.\n\nHowever, even as I'm feeling super anxious about it, I know rationally that I didn't do anything wrong.\n\nI don't actually say rude stuff to people, I don't actually touch people inappropriately. Nobody ever calls me out on anything I'm saying or doing in the moment, and everyone still likes me afterwards and wants to hang out again. And though this has some connection to the alcohol, I'm not raging drunk/blacking out. So I'm not just forgetting bad things that actually happened, or being 'that drunk guy.'\n\nSo even while I consciously know all this, it doesn't keep me from having a miserable several hours the next day. The logic of it has no control over the general anxious feeling. \n\nEventually, usually by that evening, the anxiety wears off, but it's so bad in the morning, that I'm worried this might start changing my social behavior just to avoid those horrible mornings. And I feel like if I start avoiding social events to avoid the anxiety the next day, now my issue has gotten even more damaging.\n\nAnyway, is this a known type of social anxiety? Is there a specific name for it? Other than just never drinking during social occasions (which would suck because basically every social gathering I and my friends have seems to involve drinking) do you have any tips/strategies to minimize the anxiety?", "topk_rank": 0 }, { "id": "corpus-299192", "score": 0.6356329917907715, "text": "Specifically for the tipsy part, your sense of balance comes from fluid in a channel in your ear. Alcohol is permeable to cell membranes- that is, it can freely enter the cell not requiring any special transport proteins or energy. When alcohol enters the neuron cells in your your ear to your brain, just as it does with the rest of your body, that cell gets dehydrated. These neuron cells pass information pertaining to balance to your brain based on the fluid orientation in your ear. When they are dehydrated the action potential (or neural signal) that is being sent to the brain travels much slower because the ions can’t diffuse as quickly across the axon (the channel of the neuron that passes the signal to the next neuron). Therefore when you are falling slightly off balance, the signal doesn’t reach your brain fast enough to adjust and fix it. Edit 1: I’m a 4th year biomedical engineering student. I learned this in my senior level cell biology course. Edit 2: grammar", "topk_rank": 1 }, { "id": "corpus-2390353", "score": 0.6356043219566345, "text": "I get that people get into drinking and sometimes become a lot of fun. That's a good thing. I'd never call it a problem, but I do think it's a problem when people start drinking heavily without a care in the world. I don't do this, but I know other people who do it.\n\nPeople who constantly drink are terrible people. Drinking too much is a huge problem. I'm not trying to defend people who do this, but I do think there are some people whose drinking problem is not as severe as what I'm talking about. Just because you're happy when you're drunk doesn't mean it's a good thing. I feel like that's why I see a lot of people drinking, it's a way to loosen up.", "topk_rank": 2 }, { "id": "corpus-2038288", "score": 0.6355475187301636, "text": "Also - and I really really want to believe the answer to this is yes ...... is it possible to go from being a ‘problem drinker’ (high functioning alcoholic) to a moderate drinker .... with help support maybe therapy? Love to hear your thoughts (first time poster long time lurker / commentor)", "topk_rank": 3 }, { "id": "corpus-1971804", "score": 0.63544762134552, "text": "Title. I’m 21, never drank before then. I’m on a trip to Disney World and I’m afraid drinking a few days in a row would affect me negatively. Because of course health anxiety would kick in lol. Not like, binging and being drunk everyday. I typically barely ever drink. I wouldn’t get alcohol poisoning from this, right? Thanks.", "topk_rank": 4 }, { "id": "corpus-2037414", "score": 0.6354390382766724, "text": "I know this isn't positive like most of the posts I see, but I don't know what to do anymore. I'm 24, it's been a problem for years, but I just haven't been able to make the \"Monday is day 1, and I'll go a week\" change yet. I don't remember the last time I went a few days without a beer. \n\nI need support but I haven't found it yet. So I want to give this sub a try.", "topk_rank": 5 }, { "id": "corpus-1642867", "score": 0.6354321837425232, "text": "It was my friends birthday. A group of about 8 were at our friends small hotel his family owns downtown for his dinner. We sneaked upstairs to have a drink or two. No big deal.\n\nIts no big deal until some one decides to drink too much before we had even got home. One friend named lets say, Jake, decided to have a few more than we all had because \"he wasn't feeling tipsy\". Okay what ever he'll be able to make the right decision. So we thought.\n\nBy the time we had left the hotel and headed to birthday kids house, Jake had at least 10 shots. This is an absurd amount already, and he's not looking too good.\n\nWe are now home and wow what a surprise, Birthday kid, lets call him Carl now had his older brother have a large get together for him. It was great a lot of fun. Good party. And yes there was drinking and smoking here. Jake thought he was good and kept on drinking. Now he really wasn't looking good.\n\nWe were now doing our best to keep him from drinking but when he went to go to the bathroom or so we thought he would drink more. He is at very dangerous amounts of alcohol in his body now. He has passed out on the couch and pissed his pants and onto the couch. He's done for the night.\n\nSo we put him in the bathroom where hed be the safest. Jake is now violently throwing up and has hit his head. and He's bleeding. Oh shit. Not good, not good at all. We all thought hed be okay though even though in hindsight this was a terrible situation we were in. He could have died and it would have been our fault.\n\nJake woke up the next day very hung over and threw up on his way home. This was one of my worst nights and has brought me to the point where I can not stand parties with drinking.\n\nPlease be safe when partying and always make sure to limit drinks to some one who you might even think will drink too much or already is. Its hard to do but its the responsible thing.\n\nSorry no TL; DR. this experience can not be summed up in a short amount of words.\nAlso sorry about grammar, threw this together in a minute or two.", "topk_rank": 6 }, { "id": "corpus-2037772", "score": 0.6353332996368408, "text": "A few months back I stopped drinking. 7 days later I went to a party and decided to have just one. One turned into a LOT and a 2 day hangover. Haven't had a drink since. \n\nLast night we went to a dinner at the same friends' house. When asked if I wanted a drink I said \"not now, I'll catch up later\" and that was that. Didn't drink at all. I always thought I maintained myself very well while drunk but watching my friends slowly get drunk and hear the volume of speech increase, or fumble to make a point, or just look like a drunk telling a story made me think, \"good god I must have really been a jackass\". \n\nSlept in this morning, didn't wake up 3x during the night, headache free for about 2 months running, feeling good. \n\nIf you're on the fence about quitting, yes you'll feel deprived for about a week maybe but do what you gotta do to get through each day and after a few days or weeks or months (your mileage will vary) you'll realize that YOU ACTUALLY FEEL PRETTY GOOD which is something you won't feel while you're drinking.", "topk_rank": 7 }, { "id": "corpus-644588", "score": 0.6353191137313843, "text": "I had a semi-drunken dispute with a friend about this scenario, can anyone give some hints please ? \n\nThank you for your comments. \n\n[edit] It seems my question is not science... sorry and have a good day. Also, can anyone suggest a more suitable reddit to post this to ?", "topk_rank": 8 }, { "id": "corpus-2011228", "score": 0.6352406740188599, "text": "For clarity: I get it, its spreading it more community places, but Im curious if thats more coming from restaurants, bars, establishments of that nature. My little brain wouldnt guess a shopping trip for 20 minutes to Target or Kroger is causing the issue (youre always moving, not catching up for an hour over a beer with a friend who havent seen since Christmas, etc)", "topk_rank": 9 }, { "id": "corpus-16046", "score": 0.6352384686470032, "text": "I was a heavy drinker (about a pint of whiskey per night) for decades. I stopped drinking about 5 years ago but will still have a few on vacation or holidays. I can still drink the same amount I always did. Your mileage may vary.", "topk_rank": 10 }, { "id": "corpus-98045", "score": 0.6351597309112549, "text": "Obviously this isn't a perfect description, but brought together from several hypotheses and personal experience. First of all, a lot of things get lost when you drink. Fluids, sodium, other chemicals that tend to help everything function well. Eating unhealthy food loaded with salt usually helps with the sodium depletion. (Another thing that actually is supposed to help are B vitamins. I've tried it and it seems to work to help the headaches) More importantly- carbs and sugar. Especially greasy stuff. Our bodies make more acid the more we drink. This is sometimes why we throw up, but also why carbs are great, because it \"soaks\" all the acid up. Sugar is also depleted during drinking, so sugar and carbs make you feel more normal. There's a lot more I could talk about but I'm trying to keep this shortish.", "topk_rank": 11 }, { "id": "corpus-940939", "score": 0.6351518630981445, "text": "I'm having a hell of a time keeping that first morning drink down. I always get halfway through it then I have to puke and rally. I drink about 1/2 to 3/4 handle vodka a day. Should I get some tums or something? My poor esophogus is going to fail well before my liver does at 26. Anybody got any secrets to avoid the morning puke?", "topk_rank": 12 }, { "id": "corpus-591253", "score": 0.6351460814476013, "text": "so im here, like many times before, its well past 6 - 12 hours since my last drink and while I am sleepy due to poor sleep from the booze, (will take a nap); i am literally in fear that if i dont drink tonight will the withdrawals get worse? ive stopped cold turkey a year ago for 2.5 months and didnt have major withdrawals just minor insomnia and some anxiety—in fact i was so happy by day 7 it was amazing. why suddenly i think the worst will happen (such as DT’s) and moreover I am actually considering doing an inpatient detox \"just in case..\" to be medically supervised. should i tough it out and see what happens...? this is so annoying.\n\nEDIT: i meant to spell severe correctly in the title LOL. And from some of the comments i drink 10-12 vodka sodas a night (only at night) its actually about 6-7 actual drinks but with the heavy pour the number of units i doubled hence the 10-12 above.", "topk_rank": 13 }, { "id": "corpus-1366294", "score": 0.6350975036621094, "text": "One of the worst negative effects of drinking--in my opinion--is waking up in the morning with crippling anxiety about how far off course my life has become. \n\nIt really bugs me. I usually wake up right around first light (about 6:30am where I live) and the anxiety of my impending day and dealing with the consequences of my drinking begins. \n\nAt this point, I swear off drinking for that day and head to either work or school, only to start craving drinks toward the middle of my day. \n\nToday I looked at the academic progress report for my school, and it looks as though I've tacked on yet another extra quarter to my graduation period, because of the poor decisions I've made these past weeks. I'm really let down about this. There's a lot of pressure on me to succeed, and I feel like I'm failing myself and others. Starting a new sobriety streak right now, and hoping this one sticks. \n\nReally want to find some sort of support group, but have trouble finding the courage/motivation to head to AA. \n\nAnyway. Just needed to vent. Pretty rough day. Any comments help. Thanks.", "topk_rank": 14 }, { "id": "corpus-590659", "score": 0.6350279450416565, "text": "A little over 5 months sober and the past week or so I have been hit with a horrible wave of what feels exactly like PAWS did in my first 90 days. Depression, horrible anxiety, awful brain fog that feels like dementia honestly, sex drive nonexistent, awful cravings not because I really want to drink but just because I want to stop feeling like shit, etc. Someone please tell me it’s gonna go away again like it did before? I hate feeling like this.", "topk_rank": 15 }, { "id": "corpus-2037972", "score": 0.6350101232528687, "text": "Had my uncle and aunts anniversary bbq for lunch, then like 2 hours later go to my bf's moms for fathers day and we stayed until 8. I was already tired due to poor sleep the night before so I went home for about 1.5 hours before bf called saying he left his wallet in my car. So I went over to give him his wallet and got brought along for a party he was going to with friends. I decided after 2 years no alcohol that I would try a small drink because my bf had said before that he wished I would drink in those kinds of social gatherings so I thought I would try. Had an Oz of vodka in a 16oz cup with water, ice and water flavouring. After about 1/4 of the drink I could feel it affecting my head, by the 3/4 mark I was feeling physically sick. I left after an hour because I just couldn't handle so many people I didn't know well along with already feeling tired from an exhausting day.\n\nWent to his place to spend the night and going to sleep I felt off. Woke up and feel off.\n\nI told him I'm not drinking ever again. It tasted gross, it just made me feel unhappy, didn't help me Socially. Definitely regret doing that.", "topk_rank": 16 }, { "id": "corpus-1593588", "score": 0.6349488496780396, "text": "alright, they probably don't, but to me they kinda do and that's all the justification I need. \n\nYesterday I woke up at like 2:36 am just like I do every night where I binge drink hard. Jim Carrey's The Number 23 had a profound effect on my psyche I swear because I wake up at 2:30-*something* every morning. Actually, that movie is kinda dumb. It seemed better when I was an angst-filled emo teen. As an angst-filled emo grown ass bitch, it's less remarkable.\n\nWhere was I? Oh yes, I had to work yesterday and it was awful. I have an emergency stash of vodkation in the spare tire in my SUV and after many moons of marinating in those cold, greasy confines, it's day had come. I was doing clerical work in a private office and was like...imma go grab those little dudes. \n\nI showed some restraint for once and only drank two 100ml bottles over the course of my shift and tbh it made me more productive. The buzz wore off way before my shift ended (*way* before, i had to drive home and get terrible anxiety from driving even when sober) and my boss came in and basically commended me for how much work I am able to get done on a daily basis. \n\nHe asked me if I wanted to work from home tomorrow (today) on a particular project and I dutifully agreed. I got up at 2:37 this am (got that extra minute in) and completed the project about an hour ago now. Then I took about 6 shots, did a little tai chi, and began writing this post.\n\nI feel great. Day drinking on an empty stomach is my religion. Now, for a Mtn Dew Game Fuel and four more shots.\n\nHave a good day you boozehounds ily", "topk_rank": 17 }, { "id": "corpus-730093", "score": 0.6348752379417419, "text": "Hey guys,\nSo, I was downing 6-8 drinks a night regularly for a little while. I've recently cut back to 2 glasses of wine with dinner. And while I feel **much** better, I've noticed that sleeping has been a pain. I am averaging 3-5 hours a night, as opposed to a solid 8.\n\nThis normal? And also, what do you guys do to help with this?\n\nKeep up the good work!", "topk_rank": 18 }, { "id": "corpus-107157", "score": 0.6347755193710327, "text": "There have been studies showing that sleep deprivation has similar effects to alcohol intoxication - perhaps explaining a little why you don't feel good. Judgment becomes impaired, you get cranky and impatient, even nauseous, and for those of us with chronic migraines sleep deprivation can be a trigger. Everyone responds (slightly) differently, but it sounds like you need to stop staying up late. Even if you feel fine in the morning, long-term chronic sleep deprivation has been shown to damage your brain and have serious negative health implications. TL;DR: The five-year-old answer is your brain really needs sleep and it's telling you to go the f*ck to bed - what better way than to make you feel like crap so you'll lay down.", "topk_rank": 19 } ]

[ { "id": "corpus-325404", "score": 0.8009915947914124, "text": "> is there an actual pattern for what memories you lose first when you suffer memory loss? In the case of Alzheimer's, yes. As another comment mentioned, 'dementia' is a broad category that can mean a lot of things, and there are also many different causes of memory loss. Different brain regions have different roles in memory, and store different types/duration of memory. With the progression of [MCI to severe Alzheimer's](_URL_0_) the affected portion of the brain expands to encompass more brain regions and by extension more cognitive functions, in a somewhat predictable pattern. There are other things going on too but this is the main reason you see an increasing number of *types* of cognitive impairments with time - more brain regions are being affected." } ]

[ { "id": "corpus-141175", "score": 0.7412281632423401, "text": "There are lots of different kinds of memory. One kind of memory is for remembering things that happened a long time ago. Another kind of memory is for remembering things that happened just a few seconds ago. Another kind of memory is for remembering how to *do* things like talk and drive a car. People with amnesia don't lose all of them. They usually lose the first one or maybe the second one. They don't usually lose the last one. Edit: \"just a few seconds ago\", not \"yesterday\", to give more accurate description of short-term memory, per ImNotJesus.", "topk_rank": 0 }, { "id": "corpus-322857", "score": 0.7385182976722717, "text": "It's more a decrease in the ability to store things in short term memory and to transfer short term memory into long term memory. Remembering things stored in long term memory prior to loosing the ability is mostly intact, just normal forgetting long term stored things or maybe some loss of that, also. It really has nothing to do with \"quantity\" of stored information. It does not happen to everyone. I have met many people in their 80's and 90's who seemed to me to have no loss of mental capacity at all.", "topk_rank": 1 }, { "id": "corpus-181629", "score": 0.735621452331543, "text": "Generally these conditions get worse over time and people recognise that they are forgetting things that they should be able to remember easily. These days most elderly people know that dementia or Alzheimer's are likely to be the cause when this happens too frequently, eventually however there may come a time when they even forget about the condition.", "topk_rank": 2 }, { "id": "corpus-182061", "score": 0.7343729734420776, "text": "Alzheimer's disease affects the retention or creation of memory. Use this metaphor to help you: Think of your memory as a huge stack of paper. Every time you need to remember something, you flip through the stack until you find the right page. When you need to remember something else, you place the page you were using on the top of the stack. This process continues, and the most used pages tend to be on the top of the stack. However with Alzheimer's disease, a person going through their 'stack' has a chance of accidentally dropping that page, losing it forever. This means that the most recently used pages tend to be lost sooner. Eventually, the person's stack begins to dwindle, the victim starts to pull pages from lower and lower parts of the stack as pages are lost. This dosen't answer your question: What about language? Well, language is on every page. The victim has used it throughout all of their life, and is present in all of the memories. I hope this helped.", "topk_rank": 3 }, { "id": "corpus-145384", "score": 0.7340080142021179, "text": "Because there are different types of memory that are 'stored' differently. The two most important types here are Episodic Memory and Semantic Memory. Episodic memory is recalling specific events or experiences. For example, if I asked you what you had for breakfast this morning, that would come under Episodic memory because you're recalling a specific event. The other is Semantic or Procedural Memory, which is remembering facts, concepts or skills. So, for example, you know what the word 'notebook' means, but you don't remember exactly when you learned that word, or remember when you learned what a notebook was. So, when people lose their memory, they may lose a portion of their Episodic memory, but they still retain their Semantic and Procedural memory.", "topk_rank": 4 }, { "id": "corpus-110327", "score": 0.7290446758270264, "text": "There are two different categories of memory, declarative (or implicit) and procedural (or explicit). These break down further; declarative memory can be broken down into semantic memory (facts, like your name) and episodic memory (things like a sequence of events). Usually when memory loss occurs, it happens to only one kind of memory (most frequently episodic), and does not typically affect all memory. So, when you forget your name (declarative semantic memory), you don't necessarily forget your language (procedural skill memory). Although you might have trouble remembering an exact definition of a word, you could still string together a sentence that made coherent sense.", "topk_rank": 5 }, { "id": "corpus-139486", "score": 0.724016010761261, "text": "That kind of memory loss does exist, although it's really rare. Language and mechanical skills like tying your shoes live in a different portion of your brain than does memory of events, though - you have whole segments of your brain pretty much devoted to handling language.", "topk_rank": 6 }, { "id": "corpus-275359", "score": 0.7235559821128845, "text": "You're talking about Declarative Memory, more specifically Episodic and Semantic memory. Remember events, feelings and our self experience of the world is a different work of remembering facts and information in general (like phone number). And when I say \"work\", I'm talking about distinct mnemonic pathways, distinct activate areas in our brains. We could talk about this specific pathways, but I think that I can help more by giving advices about keywords or articles to search. This link will give you a good start: [_URL_0_](_URL_2_). & #x200B; After you read him, try search something like \"Hypocampus and Memory\", \"Learnig and Memory\", \"The case of Clive Wearing\" (a nice start to have some fun and an good view at the difference between the memories), \"Dementia and Memory) & #x200B; Here it is a good image to enlighten the whole idea: [_URL_1_](_URL_1_)", "topk_rank": 7 }, { "id": "corpus-67956", "score": 0.7218225002288818, "text": "The short answer is there are different kinds of memory as well as different kinds of amnesia. There is retrograde amnesia, which means that you forget some or all of the past, but you can create new memories normally going forward. There is also anterograde amnesia, where you remember the past but you can no longer make new memories. Also, there are different types of memory. There is declarative memory, which is facts and memories, and procedural memory, which is skills and how to do things. Declarative memory is further divided into semantic memory for words and meanings, and episodic memory for events in a person's life. There is a lot of individual variation, but it is common for people with various types of amnesia to have declarative memory affected, but not procedural memory. [edited for a bit more detail]", "topk_rank": 8 }, { "id": "corpus-86629", "score": 0.7211703062057495, "text": "It doesn't. Memories are not really 'ordered' in any way. They can be stronger or weaker though, and this usually is linked to the memories 'emotional content' - you remember things associated with strong emotions more clearly, for example. With time, your 'inner link' to the memory fades if you don't use it much - you forget things. We certainly don't remember things with a time stamp. You experience this yourself: maybe you remember something that happened during one of your childhood holidays. You don't remember directly what year it was or how old you were. You need other hints to remember this, like \"ah, we only once went to Italy. I remember that i brought my best friend a gift from there. This must have been in 2nd grade since that friend moved away when i was in 3rd grade, so this in fact was our last summer together.\" Or something like that. You don't remember years, but you remember 'the year my grandfather died' or 'the year we went to Italy'.", "topk_rank": 9 }, { "id": "corpus-1257001", "score": 0.7200542092323303, "text": "I am a 27 year old female, soon to be 28 and for the past 10-9 years I have been experiencing gradual loss in my memory. At first I ignored it as did my doctor saying it was due to stress, anxiety, and depression but it has come to a point where my memory loss is severely impacting my ability to learn new things. I have also noticed that my cognitive abilities have steadily declined. I am thinking of going either for a masters (Data and Comp Sci) or a second bachelor's in engineering and this is alarmingly affecting my ability to do things.\n\nI used to have lazer focus and that has declined. I used to be able to read books in one sitting. Now, I would read a sentence in a book and not understand what I just read because I couldn't remember important details. When I read books (fiction and nonfiction) I used to remember the detail such as the names, important scenes etc so I can summarize later what happened in the story but that has become impossible. I also noticed that I am not learning new words which used to be something that I loved doing.\n\nWhen I am having conversations, I find myself asking the same question over and over again now.\n\nI used to remember faces well but that has stopped as well. This one day, I was in a college club and I met this guy. We talked for a little bit and when I ran into him a few days later again in college, I didn't recognize him at all until he said that we met and talked at the college club.\n\nSomething that has really alarmed me is muscle memory loss. When I do something over and over, say cutting a vegetable, I noticed that I would become faster as I spend more time doing it. And I would do things automatically, like breathing, but that has stopped as well.\n\nI have noticed that when I bend my thumb sometimes, it shakes. Not always, but sometimes.\n\nI also have a hard time distinguishing between faces, something that wasn't an issue for me.\n\nI have a hard time distinguishing between similar things now which wasn't an issue for me before.\n\nI used to be very good at recognizing places. I would remember the places I have been to when I am walking through the place again. That has stopped as well. I don't remember or recognize houses places that I have been past two to three times.\n\nI would remember the things that happened during the day. But now it's more like faint patches and I can't recall details fast and well.\n\nI used to be good at playing board games. Learning new rules to play a new board game is hard now because I forget the rules.\n\nI had really bad sleep hygiene, eating habits in late HS and college and I thought that was the problem. I have been working on eating healthy, having a routine, getting 8 hours of restful sleep. I exercise daily. I was very social and became lonely in HS and college. I have been working on becoming more social as well.\n\nThese things have improved my situation a little but hasn't made a significant impact. It has been two years since I made these changes.\n\nI feel confused a lot.\n\nI have made an appointment with a neurologist. I had an MRI done and the doctor said there was nothing. Bloodwork also came out normal.\n\nI have had low blood pressure and cold hands and feet since I was 14. My doc told me to eat salt when BP is low. I also have clammy skin. \n\nDo you think oxygen therapy (hyperbaric oxygen) will improve my situation if I have brain damage or something?", "topk_rank": 10 }, { "id": "corpus-2237864", "score": 0.7184023261070251, "text": "Hi everyone,\n\nI guess I'm mainly posting for emotional support here.\n\nIn the past few years, my mother (70 years old) has been experiencing increasing issues with memory loss - beyond just the normal \"slipped my mind\" type of thing. All of this sort of came to a head last night when my aunt called me to tell me that my great-aunt had passed away a couple of weeks ago, and she was concerned my mom forgot to tell me. When I called my parents to ask about this, it turns out my mom didn't just forget to tell me her aunt passed away...she had totally forgotten that her aunt passed away entirely. I essentially had a total and complete breakdown at finding this out, because this is kind of a really big thing to forget. She later called me and told me that she remembers her aunt passed away (\"Of course!\") just she was making dinner when my aunt told her about it, so it slipped her mind and she forgot to tell me (for two weeks). From her wording, I'm not entirely sure I believe that she actually remembered, since it sounded an awful lot like the story my dad gave about what happened - I'm not sure if she actually remembered this happening, or if she's just repeating what my dad is saying happened until she believes it.\n\nMy mom is (and probably always will be) extremely stubborn, and doesn't really like to admit that this is a thing that's going on, even though it's really impossible to miss at this point - she basically doesn't want to talk about it at all. I think she seems anyone bringing up her memory issues as a personal attack, so she pretty much shuts it down immediately or laughs it off and changes the topic. She saw a neurologist a few years ago, but had a really negative experience, and has been very reluctant to see anyone since, though she has an appointment with a new neurologist this week to get a second opinion (which, in light of all this happening, is good timing).\n\nI'm just feeling scared - my parents had me when they were older, so I'm only 29, and I feel like I'm losing my mom when I'm still barely an adult myself. I'm not sure if I have any questions, or anything concrete like that...I just wanted to share in hopes that I can get some emotional support and guidance about what to do. None of my friends are going through this, so I don't really have anyone to talk to outside of my family, who is being affected directly by this the same way I am.", "topk_rank": 11 }, { "id": "corpus-24302", "score": 0.7163199186325073, "text": "The type of memory they lose is called [episodic memory](_URL_0_), which is stored differently in the brain than language or learned skills.", "topk_rank": 12 }, { "id": "corpus-186006", "score": 0.7160618305206299, "text": "Memory isn't a single thing. There are many different types of memory, which are physically based in different parts of the brain. The common types are episodic memory (memory for events), semantic memory (memory for ideas), procedural memory (memory for how to do things), and working memory (the type of memory that allows you to remember things that are happening second to second around you). It's possible to lose one without losing others. For example, people who have Alzheimer's disease tend to lose semantic memory first--forgetting the names of things and people--even as their episodic memory for long-ago events is often fine. Language is an incredibly complex process that involves pretty much all those types of memory, as well as a bunch of other specialized brain structures. People who suffer brain damage often do have language problems, but they're specific--so not being able to speak as fluently, or having trouble understanding people, etc.", "topk_rank": 13 }, { "id": "corpus-182787", "score": 0.715847909450531, "text": "Amnesia is usually a symptom of a bigger disorder or injury. Alzheimers patients suffer a form of amnesia called anterograde amnesia, the inability to form new memories after the onset of the disorder, the disorder itself causes the degradation of brain tissue. As the brain begins to slowly die it loses the pathway connections that form memories, control motor functions, and eventually, cognitive thought Retrograde amnesia is when an injury or sudden onset complication causes the loss of all memory from before the amnesia Edit: spelling", "topk_rank": 14 }, { "id": "corpus-100050", "score": 0.712537407875061, "text": "We remember different types of things with different components of the brain, and they can fail independently of one another. So you might lose [episodic memory](_URL_1_) of things that have happened to you without losing [muscle memory](_URL_0_) for the action of walking or [semantic memory](_URL_2_) for what words mean, facts about the world, history and so on. Fiction writers usually emphasize this kind of amnesia because it gives a character a mystery to solve and a motivation without reducing their capacity to solve it. Actual amnesiacs can present in a lot of different ways.", "topk_rank": 15 }, { "id": "corpus-37220", "score": 0.7120179533958435, "text": "Amnesia sufferer here (retrograde and anterograde). It manifests differently for each person depending on which part of the brain was damaged. It's not like a disease that simply turns on or off. My memory center was affected. I lost everything for in about an 8 month span- a few months after and many months before the accident. Memories at the edge of either end of that period are unreliable. Other people in my BI (brain injury) support group have different experiences. I can tell you that losing that much time is rare. Also, TV amnesia is rare too. People don't forget who they are very often at all. I did change *who* I was, however. I'm a modern day [Phineas Gage](_URL_0_).", "topk_rank": 16 }, { "id": "corpus-157897", "score": 0.7079111337661743, "text": "Alzheimer's slowly destroys the brain's ability to do things, how fast and in what order varies from patient to patient, but they eventually \"forget\" how to breathe", "topk_rank": 17 }, { "id": "corpus-126374", "score": 0.7078335881233215, "text": "There are many forms of amnesia and what you forget varies by what part of the brain is damaged and how severely it is damaged. There are types that do forget language, mathematics, basic knowledge, family/friends, self identity, and many other things.", "topk_rank": 18 }, { "id": "corpus-56356", "score": 0.7072587013244629, "text": "To some extent, yes. There is evidence that memories tend to fade if not accessed. It seems that our memories act somewhat like DRAM...to remain, the memory must be read (accessed), and then re-stored. So your old memories are not just memories, they are memories of memories. This has been demonstrated by inhibiting the re-storage mechanism. If you do this and cause selective recall, you can actually seem to erase some memories. The memory is recalled, but then can't be re-stored.", "topk_rank": 19 } ]

[ { "id": "corpus-325405", "score": 0.8550411462783813, "text": "I find it a little unpleasant but since there have been 'successful' [head transplants](_URL_1_) then yes, in theory a brain transplant could be done. Challenges are mainly with scarring of nerve tissue such as the spinal cord. - _URL_0_" } ]

[ { "id": "corpus-176913", "score": 0.8119421005249023, "text": "There is no such thing. No one has ever successfully transplanted a human brain into another body. If they could, the brain would carry the personality and memories, as you suspect.", "topk_rank": 0 }, { "id": "corpus-169199", "score": 0.811724066734314, "text": "The question is fine, but the logic is a bit flawed, as you say, our consciousness is seated in our brain, so a brain transplant would not be done to save the recipient body, but to save the brain.", "topk_rank": 1 }, { "id": "corpus-106813", "score": 0.8043482899665833, "text": "Isn't this question literally unanswerable at the moment? Brain transplant has never been done", "topk_rank": 2 }, { "id": "corpus-298964", "score": 0.7884976267814636, "text": "If you are referencing the recent post here on Reddit, I would caution you that even with all the progress implied by that post, with even the best current technology, we cannot perform a human head transplant. That being stated, there is absolutely no way to answer this question without an unhealthy dose of speculation.", "topk_rank": 3 }, { "id": "corpus-286471", "score": 0.7875940203666687, "text": "Currently, absolutely not. While it might be plausible to remove a hemisphere from somebodies head, insert it into somebody else's body, give them immunosuppressants such that they didn't destroy the foreign material (aka brain), steal enough blood supply to keep the brain healthy... all of the nerves into the brain (optic tract, olfactory tract, all of the cranial nerves and the spinal chord) while have been severed. Currently, we are unable to hook them back up. And I do not see it as being likely to be possible until we have functional nanorobotics. Even the first bit would be incredibly challenging (just the removal surgery) because of how large, and delicate the brain is. i.e. it can not support its own weight, and in incredibly vulnerable to anoxic damage.", "topk_rank": 4 }, { "id": "corpus-1185064", "score": 0.7808161377906799, "text": "I think the idea of a soul is going to go out the window the second we successfully transplant a brain, I'm interested to see how the surgery is going to go for that guy who volunterred.\n\nFurthermore, if we get the technology to do backups of the information in our brains that presents another problem. If we die after committing a crime and revert to a backup before the crime, are we then held accountable for it, even though we technically had no part in it?", "topk_rank": 5 }, { "id": "corpus-294983", "score": 0.7801815271377563, "text": "The brain would still die of old age, but not as quickly as without the transplant, because other organs usually fail from old age before the brain. The biggest obstacle would be somehow attaching all the afferent and efferent nerves (all the neurons which send info from the body to the brain and send commands from the brain to the body) up to the brain such that they still worked properly. We really have no way of forming those connections, and even if we did, it's very likely that they would not convey information in exactly same way across individuals, so the signals you got even if they were connected would probably be nonsensical. If you could somehow attach all the nerves and train them to communicate with the new brain properly, the primary obstacle remaining is organ rejection by the immune system (I rank this as the secondary problem because we're closer to solving it, but it would definitely cause death very quickly if not addressed).", "topk_rank": 6 }, { "id": "corpus-3063", "score": 0.7740903496742249, "text": "When we transplant other organs, we mainly have to reconnect tubes (blood vessels, intestine, etc.). If we were to replace the brain, we need to reconnect the nerves which we don't know how to do on such a large scale. At least that is my current understanding.", "topk_rank": 7 }, { "id": "corpus-107537", "score": 0.7714594006538391, "text": "For any organ transplant, you need to connect the new organ to the host. For most organs, that means some rational number of blood vessels and physical attachment to the surrounding structure. For a brain transplant you'd have to reconnect all the individual nerves...it would be like trying to replace a computer processor with tens of thousands of super tiny pins with no connector. We don't have the surgical techniques to do it with enough speed or accuracy.", "topk_rank": 8 }, { "id": "corpus-1467580", "score": 0.7699844241142273, "text": "This sorta serves as a follow up question to my previous post. I know this isn't outside the realm of reality because back in 2017, an Italian doctor tried to transplanting someone's head onto another dying person's body. \n\nIf the procedure was successful and can be replicated, would the person with the transplanted brain be considered the same person and thus his soul still intact? \n\nWould god still welcome him?", "topk_rank": 9 }, { "id": "corpus-1270345", "score": 0.7600380778312683, "text": "I am currently gathering resources to conduct an experiment on consciousness expansion through multi-brain cognition (using brain organoids as a second home for the mind) at UCSD. I have the expertise and access I need, but require funding still. Thus, I wondered if you knew any possible source of funding for it. The theorems we are testing will almost certainly lead to consciousness transfer, and radical life extension; this, because if the mind can migrate outside the body, then the body can be restored on a more fundamental level than ever before.\n\nI have attached the theorems, since all their details are not necessarily amenable to quick summarization, but the essence of both is that the human mind is a product of cognitive operation, and these operations can be extended using modern technology such as Brain-Brain Interfaces (BBIs), Brain-Computer Interfaces (BCIs), or Direct Neural Interfaces (DNIs). Doing this allows us to momentarily move the mind outside of his original brain, by splitting it among multiple vessels, and in so doing, permits us employ decellularization and scaffolding techniques to regenerate the body without destroying the mind.\n\nAny feedback you can provide would be most appreciated.\n\n\n\n&amp;#x200B;\n\n", "topk_rank": 10 }, { "id": "corpus-108771", "score": 0.7597151398658752, "text": "Repairing serious spinal cord damage is the last thing needed in order to make head transplants a reality. I think that the doctor planning the head transplant basically said \"We're going to do this in 2017 **if** we've figured out how to reattach spinal cords yet. I think we'll have it down by then.\"", "topk_rank": 11 }, { "id": "corpus-2598169", "score": 0.7540306448936462, "text": "If i could pay a surgeon to transplant my brain into someone elses head, would my conscience go with it? Could i keep taking peoples bodies again and again until my brain died?", "topk_rank": 12 }, { "id": "corpus-105449", "score": 0.7533668279647827, "text": "It is theoretically possible, and it has been done before, but it's far from ideal and it's generally avoided when possible. This is because going through a second round of an organ sitting on ice, without blood flow, and dealing with yet another immune system decreases its viability. Here's one article about a [re-transplanted kidney](_URL_1_) and one for a [heart](_URL_0_)", "topk_rank": 13 }, { "id": "corpus-56136", "score": 0.7518390417098999, "text": "I'm not a surgeon or doctor of any sort, but I would think this sort of thing might hypothetically be possible. The risks would be that the body rejects the replacement skull or that it allows infections to get into the brain. But, there's no earthly reason to actually do this. When the NIH is handing out grant money they don't usually take \"Shit would be tight\" as a valid justification for why you should get funded.", "topk_rank": 14 }, { "id": "corpus-141568", "score": 0.748007595539093, "text": "\"You\" are your brain. Everything that you think/feel/know is in there. If you were to get a brain transplant, think of it more like a whole-body transplant. You would be in a new body. The person who received your body would be \"in there\". You are getting a new body: your body isn't getting a new brain.", "topk_rank": 15 }, { "id": "corpus-315465", "score": 0.7474580407142639, "text": "Spinal cord injury researcher here. You are absolutely correct, we have no idea how to repair a typical SCI... however, in this case the nerves of both patients are likely fully intact, making it a much easier job than coaxing cells to regrow following an injury. That being said, I agree with u/AHoddy that this is extremely unlikely to work. This is more of an experiment to see what will happen as well as a \"last-ditch\" attempt to save a terminally ill patient. Also, thank you for calling the procedure by its proper name: a body transplant. It irks me to no end when people call it a head transplant.", "topk_rank": 16 }, { "id": "corpus-8960", "score": 0.744075357913971, "text": "In a more philosophical sense the dilemma you're describing is known as the [ship of Theseus](_URL_0_). If you're asking if neuron replacement is possible the answer is \"hell no\" in the foreseeable future. Humans have some 20 billion neurons, each of which connects to thousands of others. Trying to replicate that sort of complexity is utterly impossible without decades worth of breakthroughs in nanotechnology. Your brain stores its memories in the connections between the neurons, so if you somehow were to replace all neurons in you with exact replicas nothing would change. Your brain doesn't have a metaphysical part (\"soul\") to it. Like cogs in a machine the neurons would continue to fire just as normal. Sure, it'd be an entirely different brain composed of entirely different atoms but the end result would be identical to the original one.", "topk_rank": 17 }, { "id": "corpus-281086", "score": 0.7431966662406921, "text": "In theory it is possible It's mostly down to the importance of inter cellular signalling and complexity of signalling between the cells including the connections beyond the brain which we cannot replicate yet, also replicating the correct nutrients to flow through the brain would exceptionally difficult due to the controlled environment of mammalian brain Brain isolation is a bit far-fetched today , if you had unlimited resources maybe, but there is currently plans for a human reattachment of a human brain to another body: look up Sergio canavero", "topk_rank": 18 }, { "id": "corpus-1107103", "score": 0.7430709600448608, "text": "Note: Just as a heads up, I know head transplants are currently not an actual operation. However, given the advancement of medical science, it likely soon will be. Only just a few years ago, you could not do face transplant, hand transplants, or fecal transplant. Now you can. I am certain that in preparation there is someone who has officially coined a term for it. Plus head transplants actually have been performed as early as 1954 by scientist Vladimir Demikhov. It was a dog head transplantation but it was successful, albeit the dogs would die after a few days. And yes, \"just a heads up\" was intentional. :D", "topk_rank": 19 } ]

[ { "id": "corpus-325406", "score": 0.7760487198829651, "text": "Honestly we don't possess enough knowledge to successfully transplant a brain. Its a common misconception since the enlightenment that the brain and body are \"separate\" but you have to understand that the brain also includes all your nerves that extend out from the spine to communicate with the body. Do I believe such a transplant to be possible? No but I have no definitive proof as only extensive testing could really determine if a head/brain/spine transplant could communicate with the nerves located in the recipient body. However when you consider how challenging it can be to get an \"alien\" organ to be accepted with current practices, you start to see how far off we are from a successful brain transplant." } ]

[ { "id": "corpus-115427", "score": 0.735563337802887, "text": "It has been done on animals, but they remain paralyzed. This doctor that wants to do a head transplant, wants to do it on an already paralyzed patient, that also suffers from multiple organ failure to save his life by moving his head on a healthy body. He will still be paralyzed but won't have to worry about his other organs failing him....", "topk_rank": 0 }, { "id": "corpus-108771", "score": 0.7252345085144043, "text": "Repairing serious spinal cord damage is the last thing needed in order to make head transplants a reality. I think that the doctor planning the head transplant basically said \"We're going to do this in 2017 **if** we've figured out how to reattach spinal cords yet. I think we'll have it down by then.\"", "topk_rank": 1 }, { "id": "corpus-1185064", "score": 0.7245059013366699, "text": "I think the idea of a soul is going to go out the window the second we successfully transplant a brain, I'm interested to see how the surgery is going to go for that guy who volunterred.\n\nFurthermore, if we get the technology to do backups of the information in our brains that presents another problem. If we die after committing a crime and revert to a backup before the crime, are we then held accountable for it, even though we technically had no part in it?", "topk_rank": 2 }, { "id": "corpus-315465", "score": 0.723973274230957, "text": "Spinal cord injury researcher here. You are absolutely correct, we have no idea how to repair a typical SCI... however, in this case the nerves of both patients are likely fully intact, making it a much easier job than coaxing cells to regrow following an injury. That being said, I agree with u/AHoddy that this is extremely unlikely to work. This is more of an experiment to see what will happen as well as a \"last-ditch\" attempt to save a terminally ill patient. Also, thank you for calling the procedure by its proper name: a body transplant. It irks me to no end when people call it a head transplant.", "topk_rank": 3 }, { "id": "corpus-279876", "score": 0.7216113805770874, "text": "If a patient has irreversible brain damage but the body is kept alive by life support, then sure, all the processes in the body which don't require conscious activity, such as healing, will go on. Death is a continuum, not a yes/no issue.", "topk_rank": 4 }, { "id": "corpus-107537", "score": 0.7202628254890442, "text": "For any organ transplant, you need to connect the new organ to the host. For most organs, that means some rational number of blood vessels and physical attachment to the surrounding structure. For a brain transplant you'd have to reconnect all the individual nerves...it would be like trying to replace a computer processor with tens of thousands of super tiny pins with no connector. We don't have the surgical techniques to do it with enough speed or accuracy.", "topk_rank": 5 }, { "id": "corpus-136823", "score": 0.7200076580047607, "text": "If we're talking about flawless transplant with no problems, then yes, people with younger organs have a certain chance of living longer. For example, if you have a new heart. But don't forget that your brain and the rest of your body will still be old and prone to various failure. And you can't transplant your conciousness to another brain.", "topk_rank": 6 }, { "id": "corpus-239380", "score": 0.7181627750396729, "text": "**Fair warning, the wikipedia article I link to might have some uncomfortable pictures.** There is a condition called [anencephaly](_URL_0_), where newborns only have a brain stem. Some responsive functionality still exists (touch, sound, light). But they don't survive very long. Two examples of this are [Baby K](_URL_3_) and [Baby Faith Hope](_URL_1_). As for a removal of everything except the brainstem in humans -- I have no idea. I would assume survivability would be limited. However, resective surgery in children at a young age doesn't have devastating impacts later life, as [here](_URL_2_). But the later resective surgeries are done, the worse the outcome. When parts of the brain are removed or damaged later in life there can be substantial and irreversible deficits, like with Phineas Gage and HM.", "topk_rank": 7 }, { "id": "corpus-281086", "score": 0.7179011702537537, "text": "In theory it is possible It's mostly down to the importance of inter cellular signalling and complexity of signalling between the cells including the connections beyond the brain which we cannot replicate yet, also replicating the correct nutrients to flow through the brain would exceptionally difficult due to the controlled environment of mammalian brain Brain isolation is a bit far-fetched today , if you had unlimited resources maybe, but there is currently plans for a human reattachment of a human brain to another body: look up Sergio canavero", "topk_rank": 8 }, { "id": "corpus-3063", "score": 0.7157979607582092, "text": "When we transplant other organs, we mainly have to reconnect tubes (blood vessels, intestine, etc.). If we were to replace the brain, we need to reconnect the nerves which we don't know how to do on such a large scale. At least that is my current understanding.", "topk_rank": 9 }, { "id": "corpus-104261", "score": 0.7150230407714844, "text": "No, because you need more organs than just a heart to keep the brain alive. You need lungs to cycle the O2/CO2, you need a stomach and intestines to process nutrients, you need kidneys/liver to filter the blood, etc. Now, if you were able to provide all of those things for the blood stream - basically creating an artificial body which enriched the blood with everything the brain required - and circulated that through the existing blood vessels in the brain, yes, it would remain alive.", "topk_rank": 10 }, { "id": "corpus-323705", "score": 0.7143216729164124, "text": "As has been said in previous threads on this topic, generally the answer is no. There was a recent [report](_URL_0_) of it being done successfully, but they did it shortly after it was transplanted in to the first patient. Basically, the first recipient started to reject it very quickly, and they new it wouldn't help that patient for long. So, they gave a try to transplanting it in to someone else and it worked. I feel like when people ask this question, they are picturing waiting for someone to die after having the organ for a while, and then retransplanting it. I still don't think that's a possibility, but this case opens the idea to pulling the transplanted organ from someone that initially rejects it and trying to transplant it in to someone else. I think this was the first time this was ever done.", "topk_rank": 11 }, { "id": "corpus-315476", "score": 0.7134807705879211, "text": "As long as the cells in question can be provided with nourishment, oxygen and a mechanism for removing waste, they can remain alive for some time after brain/heart activity ceases. Scientists regularly collect cells from freshly 'dead' subjects and culture these in vitro. Brain cells too can be kept alive in this fashion: electrophysiologists, working quickly, can collect a slice of brain tissue and keep it alive in a special solution while they record activity with electrodes or patch-pipettes. In your hypothetical - without any intervention, depending on temperature (cold can preserve cells for longer periods), I would say that the person's cells could last anywhere from several minutes to several hours before they become non-viable. But that last sentence was just a guess - I'm sure a cell biologist will correct me.", "topk_rank": 12 }, { "id": "corpus-289920", "score": 0.7123203277587891, "text": "Your question is actually two different questions - 1. Can the brain be kept alive by artificial means? 2. Can the body function without a natural brain? 1. Yes, the brain could theoretically be kept alive if you can maintain the cerebrospinal fluid environment and supply the brain with oxygen and other nutrients. This is the case of the isolated brain. Whether such a brain will be functional is a good question. 2. Yes, when our research in artificial intelligence reaches a point at which we could successfully model the way the brain functions in response to stimulus etc, we can technically run a body without a brain. Again, the question is of the personality etc. Will such a brain generate emotional responses to stimuli?", "topk_rank": 13 }, { "id": "corpus-249539", "score": 0.7100389003753662, "text": "Yes and no. In one sense, yes, because the brain does not produce new neurons in sufficient quantities to repopulate someplace where a bunch of them have died. There is some debate on neurogenesis and its role in the brain (Perhaps it relates to [Alzheimer's](_URL_0_) ), but something that neuroscientists agree on is that neurogenesis does not happen in the brain on a large enough scale to repair damage. In another sense though, brain damage is \"reversible\" in the sense that due to brain plasticity, other parts of the brain can pick up the slack from the damaged areas. Neuroscientist Jill Bolte Taylor recovered from a stroke, and has written a book and given a TED talk about it (search \"My Stroke of Insight\"). However, her recovery took a few years. Certainly any recovery due to plasticity will not be \"reversing\" the brain damage, but it will mitigate the loss of functionality.", "topk_rank": 14 }, { "id": "corpus-2598169", "score": 0.7078938484191895, "text": "If i could pay a surgeon to transplant my brain into someone elses head, would my conscience go with it? Could i keep taking peoples bodies again and again until my brain died?", "topk_rank": 15 }, { "id": "corpus-172025", "score": 0.7057633399963379, "text": "A [cardiopulmonary bypass](_URL_0_) is performed, connecting the patient to a machine that pumps and aerates blood in a sufficiently similar way to how the heart and lungs does it to keep their body mostly functional for the time the surgery takes. If one isn't available, and waiting isn't an option for whatever reason, the human body can be resurrected after extended periods of cardiac arrest with little or no brain damage if cooled down beforehand (though brain damage does happen often enough that this is not done).", "topk_rank": 16 }, { "id": "corpus-294831", "score": 0.7053135633468628, "text": "Sometimes blindness can be neurological. A condition called “cortical blindness” fits this description. The occipital cortex (at the back of the brain) is damaged, and the pt will report subjective blindness yet the structures of the eyes are perfectly intact. So no, eye transplant cannot solve every case of blindness.", "topk_rank": 17 }, { "id": "corpus-275236", "score": 0.7044306993484497, "text": "Yes in principle, but brain death implies the person isn't breathing spontaneously anymore. However there are a lot of brain damage situations that involve permanent unconsciousness or quasi-unconsciousness and where the rest of the body may be fine as long as the person is given food and water Also it's normal for people with major trauma to be put in an artificial coma for a few days or weeks while their injuries heal a bit", "topk_rank": 18 }, { "id": "corpus-84002", "score": 0.7040327191352844, "text": "Because it's very complicated to get everything joined up, apart from the problems of organ rejection that you get with any transplant. However, the first successful head transplant procedure has, apparently, been done on a monkey. The first human procedure is still in the future, but there is already a volunteer. The Wikipedia page is here: _URL_0_", "topk_rank": 19 } ]

[ { "id": "corpus-325407", "score": 0.8248466849327087, "text": "It's because surface area grows like length squared whereas volume goes like length cubed. That is, a bigger cup has proportionately more coffee in it relative to its surface area. So you have a much larger amount of heat you need to transport out, but only slightly more surface area that you can transport it through." } ]

[ { "id": "corpus-295471", "score": 0.7679872512817383, "text": "I've thought about this before as well. If you pour in the milk immediately, then wait a minute, that will be warmer than if you waited a minute and then poured the milk in. This is because there is a greater difference in temperature when the coffee is hot, so it gives off that heat faster than if it were cooler (with the milk in it).", "topk_rank": 0 }, { "id": "corpus-132830", "score": 0.7625510692596436, "text": "it is because the item does not retain heat long enough. water will retain temperature the longest, followed by ceramic, then metal, then wood, then that really thin plastic they make tupperware out of. So liquid in a ceramic coffee cup will stay hotter than in a metal coffee cup, and both will stay hotter than in a wooden coffee cup. the thin plastic doesnt get hot enough to cause the water to evaporate off of it. (for a more detailed answer, look at the specific heat of materials, and this will give you an idea of how warm they stay. it essentially works the opposite way for cooling, so that is why i used the term temperature.)", "topk_rank": 1 }, { "id": "corpus-101269", "score": 0.7447779774665833, "text": "Along with what the other guy said, and I don't know if this applies to Keurig or just regular coffee makers, but coffee makers force the water through a very small tube, heating it as it goes. It's much easier to heat up small amounts of water than trying to heat it all at once.", "topk_rank": 2 }, { "id": "corpus-146765", "score": 0.7431254386901855, "text": "Simple answer is the amount of liquid. A tiny amount of hot liquid disperses quickly and gets cooled very quickly. A large amount of hot liquid does not disperse as quickly and subsequently does not cool as fast either.", "topk_rank": 3 }, { "id": "corpus-323745", "score": 0.7425834536552429, "text": "Yes, because of the [relationship between surface area and volume](_URL_0_), a larger cup will not have a proportionately large surface area in which heat transfer could occur. This is also something you can easily test at home.", "topk_rank": 4 }, { "id": "corpus-315515", "score": 0.7368311285972595, "text": "[As you can see](_URL_0_) Glass will conduct heat about 7 times as much as Clay. As a result, Glass will conduct away heat from the coffee significantly faster than a clay mug. This is why coffee cups are typically ceramics (clay). You can verify this experimentally by pouring coffee into both a glass and a mug, then press your hand against both at the same time. The one that feels hotter is the one that is pouring heat into your hand faster, and thus will allow the coffee to cool faster. This should be the glass. It can depend on the type of clay used though, and whether the glass is insulated or not. But this holds true if you're talking about a typical water glass vs. an earthenware coffee mug.", "topk_rank": 5 }, { "id": "corpus-296054", "score": 0.7340430021286011, "text": "As said before, hotter water means better solvent. And the longer the coffee is in contact with the water, the more caffeine will be dissolved. And there is a max caffeine (the max in the coffee itself). The french press contains a lot of caffeine if you compare it to espresso-based coffee (short extraction time). Also the darker the bean the less caffeine it contains. So yes, the way of preparation (french press) as well as the ingredients (darker or lighter beans) affect the amount of caffeine. I work as a Barista myself. So thats how i know. (if I'm correct obviously, if not, please do correct me)", "topk_rank": 6 }, { "id": "corpus-65009", "score": 0.7328652143478394, "text": "There's no difference in caffeine if you're drinking the same volume of coffee. The only explanation is that black coffee is hotter than if you add cream.", "topk_rank": 7 }, { "id": "corpus-18167", "score": 0.7326636910438538, "text": "In general, heat tries to equalize, and the larger the difference between two temperatures, the faster it happens. Think of it like this, a thermos full of coffee is 70° and the outside world is 15°. A thermos full of milkshake is about 5° and the outside world is still 15° So there's a larger temperature gradient between the coffee and the Earth, than between the milkshake and the Earth. So the coffee cools quicker than the milk warms.", "topk_rank": 8 }, { "id": "corpus-2253493", "score": 0.7317818403244019, "text": "So I've recently begun to think that maybe I could actually be having a better cup of coffee (given all the recommendations on r/ coffee) if I bought a thermometer to control my brewing temperature rather than just guessing. It turns out, the coffee ended up tasting better, but by the time I'm done brewing using the aeropress or french press, the coffee is mildly hotter than lukewarm. Is this normal? Maybe it's just a preference, but I like to have my coffee hot... So how do you all go about ensuring that your coffee stays hot after you have let it sit for 4 minutes in a french press and 1 minute+ in an aeropress?", "topk_rank": 9 }, { "id": "corpus-312338", "score": 0.7301195859909058, "text": "The coffee with two scoops will cool faster, and it has nothing to do with color. Water has higher heat capacity than coffee, which means that the higher relative water content, the more heat it needs to lose for it to decrease in temperature. _URL_0_", "topk_rank": 10 }, { "id": "corpus-51177", "score": 0.7287582755088806, "text": "A typical drip coffee machine has a set of tubing that runs from the bottom of the reservoir, into the burner below the coffee pot, and back up to above the grinds. When water goes down this tubing, it passes a one-way valve, so that the water that gets heated never mixes back with the reservoir. This means that at any point in time, the coffee maker is only heating a little bit of water, which is significantly faster than boiling the entire thing. That hot water is pushed up the tubing by the boiling action, and drips into the grinds. The reduction in pressure means the one-way valve will open up again, allow more cold water in, and more heating happens. Essentially, coffee makers are faster than a pot because they heat the water sort of 'sequentially', since only a small amount is needed at any given time.", "topk_rank": 11 }, { "id": "corpus-101683", "score": 0.7282392382621765, "text": "When things cool down, they're really just moving heat from a hot thing to a cold thing. And the movement happens faster when there's a bigger difference between the hot thing and the cold thing. But that means the process slows. The hot thing gets cooler, but the cool thing gets warmer. They get a lot closer together. In the case of a cup of coffee, it's being cooled by the air around it. And the air around it is getting warmer too. You can speed the cooling process along by getting that warm air out of the way, increasing the temperature difference between the coffee and the air around it. It's the same principle that makes a breeze or a fan cool you on a hot day.", "topk_rank": 12 }, { "id": "corpus-311199", "score": 0.7278416156768799, "text": "A lot of it is just the surface area/volume ratio. The eggs and toast are relatively thin while your coffee cup is short and fat. A thin puddle of coffee will cool much faster.", "topk_rank": 13 }, { "id": "corpus-562217", "score": 0.727637767791748, "text": "When coffee is left to sit on a standard coffee maker with a hot plate beneath the carafe, the taste of the coffee will take on more of a burnt flavour. This is why an insulated carafe with no hot plate is better than a glass carafe. \nIf you do have a standard coffee pot, take the freshly brewed coffee off the burner or turn the pot off when you're done brewing to avoid scalding the coffee. If it cools down, nuking it will warm it up just fine without making it taste charred. (Yes, to a coffee snob microwaving coffee is blasphemy, but it will give you a better tasting cup than the alternative).", "topk_rank": 14 }, { "id": "corpus-293883", "score": 0.7265350222587585, "text": "I would say you are not comparing similar events. If you put your finger in a cup of coffee, it will feel very hot cause the entire cup is contributing to the heat transfer. The same thing would happen if you took a giant gulp of hot coffee, it would burn you. Now if you took the amount of a normal sip of coffee and put your finger in it, I doubt it will burn that much. Plus when you sip coffee you spread that small amount over your mouth which has a lot of surface area and blood vessels to dissipate heat. Try spilling a sips worth if hot coffee on the table and see how quickly it cools.", "topk_rank": 15 }, { "id": "corpus-2497845", "score": 0.7264261841773987, "text": "I'm curious because each K-cup is exactly the same size, yet you have the option of 2-5 different sizes depending on your model. \n\nWhat is the difference in terms of caffeine content in each of these sizes? I've heard mixed things, though it seems like in general smaller cups are stronger and larger cups are weaker, with 8oz being the intended size. Yet someone also said that the larger size is weaker in terms of caffeine per oz, but still has more caffeine total (I guess because with larger cups it squeezes out every last bit from the coffee grinds).", "topk_rank": 16 }, { "id": "corpus-261250", "score": 0.7246713638305664, "text": "It likely has nothing to do with the coffee. When you shake very hot water in an air tight container, the air trapped in the container will heat up to the temperature of the water. As the temperature went up, and the volume stayed the same, the pressure went up. Opening the container will release this pressure.", "topk_rank": 17 }, { "id": "corpus-304731", "score": 0.7209724187850952, "text": "The same volume of creamer should chill the coffee the same amount, this would be because it has a fixed heat capacity and so would absorb the same amount of heat from the coffee. This is slightly complicated by the fact that if there is a greater temperature gradient between two objects then heat flows faster, therefore the greater the temperature gradient between the coffee and the room the more heat can be lost, so if you pour in slowly then this greater temperature gradient can be around for longer so more heat will be lost by this method. This effect will probably be pretty minimal however.", "topk_rank": 18 }, { "id": "corpus-274773", "score": 0.7207174897193909, "text": "I believe it's called diffusion (or maybe dissociation). as the sugar dissolves into the water, it will naturally move from areas of high concentration to areas of low concentration. The end result will be a nearly even distribution of sugar in the cup of coffee, although this will take some time, but the hotter to coffee, the faster this reaction will occur.", "topk_rank": 19 } ]

[ { "id": "corpus-325408", "score": 0.6573142409324646, "text": "Spherical. A sphere has the least amount of surface area per volume, and the surface is where the heat transfer happens. Less surface area means less heat transfer is possible. Since a sphere is not a practical shape for a mug, the cylinders we use now is probably the best comprimise." } ]

[ { "id": "corpus-603003", "score": 0.624441921710968, "text": "I worked as a barista for over ten years and I can't come close to this especially for a cold brew. A few local shops make a cold brew but they taste sour or \"tealike\". It's the closest thing to an iced latte I used to make at one shop that was nothing more than Davinci syrup and good espresso and good ice. I've made cold brews at home but they end up acidic and cream curdles up with it. I'm not the type to test out various methods so I thought I'd ask here first. Thank you!", "topk_rank": 0 }, { "id": "corpus-2304878", "score": 0.6244301795959473, "text": "as the title says, I'm looking for Tea Infuser / Pitcher for iced tea. I'm wanting between 1 ~ 2 liters and something for around $20. I checked amazon but the only one I could really find that seemed close to what I wanted was one for $30 + shipping and I'm kind of on the poor side. I saw some Teavana infusers (I know.. I know) but they're so freaking expensive I can't even comprehend.\n\nSo, does anyone know of one of these pitchers that I could get? If I gotta bite the bullet and get the $30 one I suppose I will, but I wanted to see if anyone in this subreddit would know of one &lt;: \n\nThank you for your time!", "topk_rank": 1 }, { "id": "corpus-2252246", "score": 0.6243619918823242, "text": "I have a Krups Brew &amp; grind which I rarely use, but it still delivers the nicest cups of coffee when against:\n\n* Baratza Vario \n* OXO temperature controlled kettle (when applicable)\n\n----------\n\n* Brikka pot\n* Moka pot\n* Mini-spresso\n* French Press\n* Chemex\n* Coffee grounds in a pot on the stove\n* Aeropress\n\n--------\n\nThe krups seems to manage in a way I don't to keep the flavors of the beans fresh &amp; full of distinct flavors.\n\nThe same beans in anything else results in a lot of muddy flavors.", "topk_rank": 2 }, { "id": "corpus-2762105", "score": 0.6243603229522705, "text": "Hey everyone!\n\nI've tried drinking tea a few times before, but I could never get into it because everything just tasted like hot water. Granted, it smelled good but it tasted just like water! So I had given up on tea for a while, but I recently discovered this sub and want to give it another shot!\n\nI read a bunch of threads and have decided on ordering a few sample sets through Adagio. Are there any that are strong-flavored ones that you would recommend? Any naturally-sweet teas? I'm open to any suggestions because I have no clue which types of tea I might prefer, so I'm going to just listen to you guys. \n\nAdditionally, I was thinking about getting the ingenuiTEA, but I'm worried about using a plastic container to hold hot water over and over again...is this a valid health concern?\n\nThanks for all of your help!", "topk_rank": 3 }, { "id": "corpus-2303280", "score": 0.6242514848709106, "text": "Atleast once a year, we have to replace our coffee machine and there are about 30 employees that use it throughout the day. Anyone got any good suggestions on one that will last?", "topk_rank": 4 }, { "id": "corpus-1648988", "score": 0.6242147088050842, "text": "So I love enjoying tea at home and would love to enjoy some at work too, but I have a small problem. All my small office has is a microwave and a water cooler with hot and cold taps. I can't seem to get the water hot enough in either device for my loose leaf teas and it always tastes somehow... off. Like it hasn't been brewed in hot enough water and tastes weak. I've tried microwaving water til boiling point and it still tastes weird to me.\n\nSo if anyone here makes tea at work, how do you go about getting your water to the right temp without a stove and kettle?", "topk_rank": 5 }, { "id": "corpus-2232974", "score": 0.6242110133171082, "text": "Looking for coffee mugs, something fun like Skull Coffee Cup, Monsters, weird stuff. Seen some things online but would much rather see it first hand, any wacky coffee mug stores in HRM?\n\nThanks!", "topk_rank": 6 }, { "id": "corpus-2499093", "score": 0.6242016553878784, "text": "I was reading a post in r/fitness (addressing some caffeine... and got to thinking that a caffeine boost wouldn't be bad before a nice ride. My only problem is coffee usually makes me need to use the restroom shortly after drinking it. That obviously wouldn't be ideal if I were to drink it right before a long ride. Are there any other options aside from the 5-hour energy drinks and soda? I do drink iced tea once in a while but I don't notice any energy boost from it; most likely because of too low of a caffeine dose. What do you use?", "topk_rank": 7 }, { "id": "corpus-1651001", "score": 0.6240462064743042, "text": "At home, I enjoy preparing black coffee using around 18g-30g of beans using my Comadante and Chemex and then drinking it on my commute in a Zojirushi travel mug. After I finish my delicious coffee, I have been tolerating the commodity coffee in the office kitchenette in order to feel something/anything throughout the day. \n\nAt my last job, pre-covid, I had my Baratza Encore and gear on my desk and a kettle in the kitchenette and brewed around once per day. I'd often split a Chemex 3 ways with any of my teammates and tried not to be too loud considering the open office floor plan. I'm not ready to rock the boat on the noise and perceived time-wasting too much yet at my new job.\n\nHow do you brew in the office vs at home?\n\nThe commercial brewer in my current office kitchenette has instant hot water that is far from boiling. Does anyone brew single serving coffee with this water? I'm thinking the aeropress could make for a good office brewer", "topk_rank": 8 }, { "id": "corpus-1079031", "score": 0.6239248514175415, "text": "I'm thinking of following these plans for my first still:\n\n\n\n* I already have a large stainless steel brew kettle and plastic buckets which is why I like this design. But I want to make some modifications.\n\n* I don't want to use hot glue since it's permanent. Will a PTFE gasket on one side of the compression fitting make a good enough seal?\n\n* For sealing the lid to the pot, he says not to worry too much but I plan to heat this on a gas stove so I'm going to worry. If I apply flour paste to the lid and let it dry before starting will that be adequate? Are there other options besides flour paste that will work just as well and be less messy? I've also seen pictures of pots with binder clips in a circle around the top, is that worth trying?\n\n* I'm pretty sure his step 9 is completely wrong. Don't you need a bit of a flare / flange on the end of the tube for the compression fitting and ferrule to push against? Otherwise what's to keep the tube from just sliding off as easily as it slid on?\n\n* I noticed that most pot still designs include a fairly large riser off the lid before going to the worm. What's the purpose of a riser and how important is it?\n\nThanks!\n\nEdit: I forgot to say that my plan is to make apple brandy, and to ask whether this design will keep the apple flavor in the final spirits.", "topk_rank": 9 }, { "id": "corpus-101683", "score": 0.6239190697669983, "text": "When things cool down, they're really just moving heat from a hot thing to a cold thing. And the movement happens faster when there's a bigger difference between the hot thing and the cold thing. But that means the process slows. The hot thing gets cooler, but the cool thing gets warmer. They get a lot closer together. In the case of a cup of coffee, it's being cooled by the air around it. And the air around it is getting warmer too. You can speed the cooling process along by getting that warm air out of the way, increasing the temperature difference between the coffee and the air around it. It's the same principle that makes a breeze or a fan cool you on a hot day.", "topk_rank": 10 }, { "id": "corpus-2745547", "score": 0.6239080429077148, "text": "I'm a college student -and I'm a beginner at brewing coffee. I have a cheap Farberware coffee dripper which was worth $20 given to me, but I'm not sure how much I'm missing out by using the cheap coffee dripper. I can buy a french press, or a non-electrical coffee dripper, but my dorm doesn't have a stove to make boiling water. My budget's fairly tight, and the max I would be willing to spend is around $50. I would prefer a smaller coffee dripper as I'm somewhat limited in space, but a large one would be fine if it's worth the money.", "topk_rank": 11 }, { "id": "corpus-2011097", "score": 0.6239008903503418, "text": "I'm hoping for some awesome hot cocoa ideas, because my prepackaged \"just add hot water\" kind just isn't doing it for me this year.", "topk_rank": 12 }, { "id": "corpus-2576754", "score": 0.6238709092140198, "text": "I doubt this will get any traction, but does anyone any an extra ROK portafilter? Like, did anyone buy the naked one and no longer need the original?\n\nI live in the US and recently bought a used ROK (missing all accessories) and thought I'd be able to buy a new portafilter from espresso unplugged or another us retailer but every single online store is sold out. I talked to one of the sales reps and they told me that they have no idea if/when ROK will be sending them more. I can't find one online ANYWHERE.\n\nSo that leaves me with a useless espresso machine unless someone out there would be willing to part with one of their old portafilters that's just sitting in a kitchen drawer (for $ of course).", "topk_rank": 13 }, { "id": "corpus-1969279", "score": 0.6237385272979736, "text": "I'm a huge coffee drinker, and I always love a good cigarette with coffee. As many other people on this sub though I'm trying to get away from analogues. Currently I have Ecto Cooler (which is kindof citrus-y) mixed with Mango, and when I have a cup of coffee with it I get a chocolate-caramel taste that I like. Any other flavors you found that you like?", "topk_rank": 14 }, { "id": "corpus-27406", "score": 0.6237144470214844, "text": "Stackable cups are *tapered* so that they're smaller at the bottom than at the top. They also stick out past the top of the lower cup somewhat, allowing them to regain the extra space lost by being inside the lower cup. If they had to completely fit *inside* the lower cup then, yes, they'd have to constantly get smaller.", "topk_rank": 15 }, { "id": "corpus-2693856", "score": 0.6237086057662964, "text": "Hi, I'm English as per title, and I've been wanting to use American recipes. What does a \"cup\" translate to? In England we use millilitres. Cheers.", "topk_rank": 16 }, { "id": "corpus-89000", "score": 0.6236850023269653, "text": "Those are stir sticks, they're for stirring in milk/sugar, not for drinking through. They're built like that so they don't bend", "topk_rank": 17 }, { "id": "corpus-1443565", "score": 0.6236597299575806, "text": "What are some methods to keep a geodesic dome cool? Like using a specific type of glass that lets less heat pass through?", "topk_rank": 18 }, { "id": "corpus-1592542", "score": 0.6236557364463806, "text": "Also l, which ginger beer do you use? I used fever tree premium ginger beer but maybe it's too strong?\n\nEdit: copper cup.", "topk_rank": 19 } ]

[ { "id": "corpus-325409", "score": 0.7060966491699219, "text": "In England 'the stiff upper lip' is responsible for the majority of male suicides. Men simply do not talk about their problems. Women will more likely go to their social group or a family relative; usually female, and debate their issues, yet in comparison men do not want this. They do not want to seek help because they are supposed to lead and solve it themselves, hence the stiff upper lip. When they reach problem that is unsolvable one of the courses of action to combat that situation is suicide. In the north east of England where there is a lot of poverty an initiative known as CALM has been introduced that presents suicide as a option that everyone considers, as a result of this programme the suicide rate in this area has dropped by 55%. Perhaps this is the way forward?" } ]

[ { "id": "corpus-77330", "score": 0.670616865158081, "text": "For a very long time, men were the ones going out of the house and doing stuff (work, errands, war, etc), while the woman stayed home and took care of the house and kids. It's pretty much a given that you're safer staying in the house all the time than you are going out into the world. Thus, men would usually die earlier than women. Nowadays, with the two genders slowly drifting towards equality, many women are out doing things and many men are staying home housekeeping. It's possible in a few generations that there will no longer be a clear consensus on which gender lives longer.", "topk_rank": 0 }, { "id": "corpus-642258", "score": 0.6701213121414185, "text": "I feel that females are always complaining that their lives are so much harder. But what things make a males life harder than a females life?", "topk_rank": 1 }, { "id": "corpus-1438726", "score": 0.6687599420547485, "text": "Recently our Ministry for Women released guidelines for gender analysis that the government should use when investigating new polices. Policymakers should consider that policies will not necessarily have the same impact on one gender as it does on another. This got me thinking about the things that policymakers should consider about men when making new policy.\n\nFor example, one thing I thought about was because men are not as involved in childcare or responsible for contraception and are basically pretty healthy up until age 40, a lot of men don't see a doctor. This means that policies to improve peoples health that require contact with a doctor will not be as effective for men. EG something like distributing health information pamphlets at doctors surgeries, or getting doctors to screen for certain types of diseases more often.\n\nAnother one is that because male suicide is often fatal on the first attempt and often there is no signs of mental illness, policies to address male suicide need to extend beyond normal mental health systems.\n\nThat's about all I could think of, but I am sure there are more\n\nWhat other gender factors for men to policymakers need to consider when making policy?", "topk_rank": 2 }, { "id": "corpus-670631", "score": 0.6677138209342957, "text": "Note I am a male saying this.\n\nWhen school shootings happen everyone talks about the race or the guns but nobody points out every single one is by a male. Evil dictators are basically all males. Males are more likely to lie, cheat and steal. They are murderers, rapists and criminals at an exponentially higher rate than women. They have big egos and treat the opposite sex worse.\n\nWomen grow up valuing relationships and love between friends, family and spouses more. They are more likely to understand there's more to life than money and sleeping with the right person means more than the number of you have. \n\nIf everyone on the earth was a woman there would be world peace and almost no crime", "topk_rank": 3 }, { "id": "corpus-1400127", "score": 0.6666913628578186, "text": "&amp;#x200B;\n\nMen are more likely to be sexually abused.\n\nMen are more victims of domestic violence.\n\nMen are disadvantaged in university.\n\nMen are more likely to be manipulated by their partners.\n\nThere are fewer male pedophiles than women.", "topk_rank": 4 }, { "id": "corpus-6377", "score": 0.6647506356239319, "text": "There's a few reasons. First men tend to do more risky jobs then women. I can't quote a source right now but I recall something like 98% of all workplace deaths being men. Secondly there seems to be an evolutionary aspect. It's related to the first reason. Men hunted and did dangerous things which got them killed. Women stayed 'at home' and raised the next generation. Their own children and grandchildren. And having those extra hands around to help raise these kids turned out to be advantageous. So the offspring of women that lived longer where more likely to grow up and make baby humans of their own allowing the trait to be passed on.", "topk_rank": 5 }, { "id": "corpus-1399706", "score": 0.6620612144470215, "text": "I just don’t get it. Men have been proven to have lower graduation rates, lower grades, and overall struggle more than women, but women are the ones to get exclusive scholarships. It doesn’t make sense to me. Men also have a lower rate of going to college than women. So, if men are the ones struggling, why in the world would people be trying to give women even more advantages.\n\nP.S: I don’t hate women or anything like that. I’m just curious why this is the case.", "topk_rank": 6 }, { "id": "corpus-672536", "score": 0.661492645740509, "text": "I'm not generalizing *every girl*. You can't deny this is a statistic.\n\nI know to a point it's upbringing. Men are definitely raised differently than women are, and that's a cultural thing. \n\nI'm saying even when girls have the same hobbies as guys do, they tend to be worse or there tend to be less extraordinary samples. \n\nIs this just because of the sample size, or is this an actual difference between men and women?\n\nPlease try to not be misogynistic in your responses. This is a serious question.", "topk_rank": 7 }, { "id": "corpus-158734", "score": 0.6608579158782959, "text": "It's not completely understood why this happens but it's thought that a mix of biochemical and social elements play a role: * Social: Men and women describe pain in slightly different ways, likely due to cultural and societal expectations and pressures. * Biochemical: Women are more likely to have coronary artery anatomy ([right-dominant](_URL_0_)) that is more likely to lead to atypical symptoms like nausea and vomiting. Also, endorphins, which can affect how pain is perceived, are released during heart attacks and can be affected differently by sex hormones present in males and females. Edit: Here are a couple of resources for those that would like to read more: _URL_1_ _URL_2_ _URL_3_", "topk_rank": 8 }, { "id": "corpus-84392", "score": 0.6598533987998962, "text": "A recent study I can't find right now actually showed that, absent environmental effects, men and women should live equally long. The difference is that men tend to engage in more risks, which can lead to early death, and until recently tended to smoke way more. Since smoking has started to drop in the US, the difference between men and women has shrunk somewhat as a result.", "topk_rank": 9 }, { "id": "corpus-642513", "score": 0.6592156887054443, "text": " - Is it because women are getting more violent, men are getting more passive, or simply because men are just reporting it more often nowadays?", "topk_rank": 10 }, { "id": "corpus-264140", "score": 0.6588039994239807, "text": "Women have a lower chance of death at all stages of life. _URL_0_ This is by no means a complete solution, but it probably helps.", "topk_rank": 11 }, { "id": "corpus-461824", "score": 0.6584600210189819, "text": "So I did some research online about the transgender suicide rate and found out that discrimination and violence against trans people is the primary reason. However, I encountered an article that seemingly \"refutes\" the argument that discrimination is the reason why the suicide rate is so high.\n\nNow I am not saying that the article is correct but rather wanted to know if it is a bad idea to compare the transgender suicide rate to the suicide rate of people of color.\n\nThe argument on the article goes like this...\n\n&gt; The second problem is that the discrimination theory of suicide does not hold up when compared to other minority groups who suffer disproportionate real and perceived amounts of bigotry and negative discrimination. The Centers for Disease Control’s numbers on suicide indicate that the highest rates of suicide over the past 15 years or so belong to…white people. In contrast, in most of the years surveyed black people had the lowest suicide rate among all ethnicities. White suicide actually rose in the period 2000-2014.\n\n\n&gt; If discrimination were truly a motivating factor for suicide, you would expect the black suicide rate to be a good deal higher than it is, if not higher outright than the white rate: blacks report overwhelmingly higher rates of perceived racial discrimination than whites, and it is reasonable to assume that actual instances of discrimination against blacks are a good deal higher than those against whites. Yet the suicide rate of the former remains stubbornly lower than that of the latter.\n\nI think that the article is wrong because I think that the black community views seeking mental health treatment or suicide as a solution for mental health issues as a sign of weakness and therefore that stigma lowers the suicide rate of black people significantly. The transgender community doesn't have that same stigma attached towards suicide.\n\nSo am I correct in that the article's logic is fallacious? Comparing the suicide rate of black people and transgender people is like comparing apples to bananas.\n\n*Note: I am not including the link to the article because I don't want to upset any trans people. Do a google search of the quote in quotation marks \"like this\" and you should be able to find the article.*", "topk_rank": 12 }, { "id": "corpus-82376", "score": 0.6583828330039978, "text": "Men are more likely to engage in risky behavior and are much, much less likely to seek medical attention for injury or disease.", "topk_rank": 13 }, { "id": "corpus-56666", "score": 0.6580684781074524, "text": "Women have far better support systems available compared to men. It's socially acceptable for women to feel hurt and express those feelings. They usually get ample sympathy and support from friends, family, colleagues and the public. When a man tries the same, he's ignored, ridiculed and perceived as weak.", "topk_rank": 14 }, { "id": "corpus-76952", "score": 0.6568371057510376, "text": "It is not just humans; studies have shown in most species, the females outlive the males. There are numerous theories and hundreds of variables, but it can be simplified and reduced to a few variables: Evolution: Women mature faster. Biochemical: Estrogen is more beneficial than testosterone. Societal: Woman are less prone to be in life threatening situations. Also societal: Woman bond better than men. Having a social circle is beneficial to survival.", "topk_rank": 15 }, { "id": "corpus-72540", "score": 0.6559317111968994, "text": "1. More men are serial killers because testosterone creates a greater perpencity for violence and lack of empathy 2. More women are victims because crime is largely committed by either A) lack of social mobility, B) invalidated emotional states, and C) greed. Women fulfill all the necessary remedies for these things in a social darwinian sense.", "topk_rank": 16 }, { "id": "corpus-140381", "score": 0.6553996801376343, "text": "Men are more prone to taking up risky professions (solder, farmer, miner, policeman, fire fighter etc). Thus more die at a young age.", "topk_rank": 17 }, { "id": "corpus-47775", "score": 0.654758632183075, "text": "For one, men tend to be at higher risk for accident. This is due partly to male culture and partly to men's historically being the more common participants in war. Beyond this, males are more at risk for many diseases due to the nature of XY sex determination. While females have an XX sex determining chromosomes, men have XY. If a recessive disorder located on the X chromosome were passed down from one parent to the child, a male child would be guaranteed to have the condition, as they have no other X chromosome. Meanwhile, a female child would have a chance that the other X chromosome would possess a dominant allele that would override it. This is actually why males have a higher incidence of colorblindness than females; the gene for colorblindness is located on the X chromosome.", "topk_rank": 18 }, { "id": "corpus-102970", "score": 0.654617428779602, "text": "They have larger breasts and therefore more physical matter that can have a mutation that turns to cancer. The hormones that seem to aid in the growth of breast cancer are in higher concentrations in females than males, so while they are subject to change on average they are much higher in women than in men.", "topk_rank": 19 } ]

[ { "id": "corpus-325410", "score": 0.7436057925224304, "text": "People are making out in this thread that synthetic diamonds are next to indistinguishable but there are quite a large number of detectable, atomic level differences. This GIA piece summarises the differences _URL_1_ The table at the start of the Identification section lists the main detectable differences: _URL_0_" } ]

[ { "id": "corpus-25962", "score": 0.7049548625946045, "text": "Oh contraire. Doesn't necessarily take time, you can substitute time for heat and that's how you can synthetic diamonds.", "topk_rank": 0 }, { "id": "corpus-867584", "score": 0.7049006819725037, "text": "I found a square cut, rather large white \"diamond\" in a parking lot. I didn't bother picking it up when I first walked by it because I thought it was rhinestone. Then I thought, \"What if it's actually real and someone is looking for it?\" So I went back and picked it up. It's a somewhat shallow cut but the bottom comes to a sharp point just like a real diamond would. It lacks the silver coating on the back that is often found on rhinestones. But there was a tiny black speck on the back of it. I assume it's the glue that once held it in place. I was going to post a picture of it but I have dropped it between the seats of my car. And I don't want to tear my car apart for a piece of cut glass. So have you ever heard of black glue being used on real diamonds?", "topk_rank": 1 }, { "id": "corpus-305072", "score": 0.7044971585273743, "text": "All these lab growing procedures need to grow the crystals very slowly (since they basically add the carbon layers one by one). This is in a way the limiting factor (see below for more details). But 1 carat is not the limit. I found 30 carat for yellow diamonds (with impurities). Or here in this paper they present a method to get a 1cm 8carat pure(white) diamand: _URL_0_ (took them 200h). Unfortunately the limit growth rate decreases as the crystal size increases (the surface area you need to grow increases with the volume - but the speed they can \"coat\" new layers on top stays the same). In other words: They grow slower the bigger they get. You can not deposit faster if you want to maintain a good quality diamond without impurities and defects.", "topk_rank": 2 }, { "id": "corpus-741533", "score": 0.7041511535644531, "text": "I had this ruby ring and diamonds checked they said the diamonds are real genuine. And the rubys was natural stones. What do you all think it’s worth? Thanks\n\n", "topk_rank": 3 }, { "id": "corpus-239258", "score": 0.6971484422683716, "text": "Depending on the factors involved, it can take from 1 to 3 billion years. Synthetic diamonds are made from any carbon rich substance (even things like peanut butter), and put under tremendous amounts of heat and pressure, thus making the time much much shorter.", "topk_rank": 4 }, { "id": "corpus-1408082", "score": 0.6947054862976074, "text": "I have been looking at Brilliant Earth, James Allen, and Rare Carat. Some of the prices on Rare Carat seem very low compared to the other two.\n\nIn Rare Carat, I have been using the filter function \"price score\" to find the best deals.\n\nLab grown 1.7 carat, ideal cut, F color, VS1. No florescence. \n\n\n\nWill it be lower quality than ones purchased from other sites?", "topk_rank": 5 }, { "id": "corpus-1659451", "score": 0.69412761926651, "text": "So you should know that diamond is made up of entirely carbon. So when the temperature reaches the boiling point it turns into a diamond gas, so that's got me thinking - isn't diamond gas basically just carbon gas? What do you think?", "topk_rank": 6 }, { "id": "corpus-282015", "score": 0.6940667629241943, "text": "In theory yes, practically no. Diamonds are not elements, but rather a specific structure of carbon atoms. Lithium, meanwhile, is an element. To create it, your would need to use nuclear process, mostly in terms of atomic fusion - literally combining smaller atoms into larger ones. This is extremely difficult, complicated, and expensive - especially if you want to produce large amounts of lithium atoms. The analogy would be that lab grown diamonds are like taking flour and turning it into bread. Synthetic lithium would be like trying to create flour itself, without starting by harvesting wheat. It's not a perfect comparison, but that's the gist.", "topk_rank": 7 }, { "id": "corpus-50196", "score": 0.6937053203582764, "text": "Mostly clarity (seeing whether the diamond is foggy or not,) and for inclusions (bascially just a fancy word for flaws within the stone.) Real diamonds are very rarely perfect, so the presence of flaws is a good indication that it is genuine.", "topk_rank": 8 }, { "id": "corpus-317915", "score": 0.6936313509941101, "text": "Here is a picture of a (natural) 35 carat diamond. _URL_1_ Some random site on the internet claimed DeBeers created a synthetic diamond that was approximately that size. There are more difficulties as the crystal gets larger, but the size shouldn't have any absolute limit. _URL_0_", "topk_rank": 9 }, { "id": "corpus-2320616", "score": 0.6935786604881287, "text": "So I found this diamond on clearorigin:\n\n\n\nSorry if sounds stupid, but does this diamond seem to have any obvious flaws?\n\nThanks in advance, and sorry again if this is a dumb question, I'm just nervous about messing something up.", "topk_rank": 10 }, { "id": "corpus-307507", "score": 0.6926316022872925, "text": "There are materials harder than diamonds, but most of those are quite specific combinations of elements which are difficult to create or maintain outside a lab. Industrial grade diamonds are cheap and easy to make, so diamonds will remain the go-to material for industrial needs.", "topk_rank": 11 }, { "id": "corpus-20299", "score": 0.6922966837882996, "text": "Most commercial diamonds now are laser-inscribed with a GIA (Gemological Institute of America) serial number, which can be tied to records that authenticate the diamond. I assume this is also done for other precious stones. You can see this serial number under 10x magnification if you know what to look for.", "topk_rank": 12 }, { "id": "corpus-27374", "score": 0.6919863820075989, "text": "There is plenty of things harder then diamonds, well a handful at least. They are however not naturally occurring or occurring in so small amounts that they are practically not naturally occurring.", "topk_rank": 13 }, { "id": "corpus-1445066", "score": 0.6915329098701477, "text": "So I was looking for lab diamonds at ebay and as usual checked for good reviews and found some sellers on the usa, the onde that got my attention is on new york but their diamonds are made on india. Have a few reviews, all good, and social media accounts so what u think? \n\nSorry for my English\n\nEdit 1 links\n\nother add\n\nlink\n\n\n3rd", "topk_rank": 14 }, { "id": "corpus-1272867", "score": 0.6912487745285034, "text": "Hi Diamond People,\n\nI wanted to get your thoughts on what looks to me like two similar diamonds:\n\n\n\n\n\nFrom the diamondscreener (thanks sproutworkshop!), I would gather from a number's perspective (table %, depth %, L/W ratio) the two are very similar. The JA diamond has a faint fluorescence, but not sure how much that matters in this cut.\n\nIt looks like the light reflects differently from the tables, but maybe that's because the 360s views of each are taken from different angles.\n\nSo I wanted to get your thoughts on what you see as the difference between the two.\n\nWhich would you prefer?", "topk_rank": 15 }, { "id": "corpus-1125523", "score": 0.6909559965133667, "text": "Because if that's the case, I doubt White Diamond is called White Diamond, more likely just Diamond.\n\nBecause I can't find any real-life examples of diamonds that are colored white. Do they exist?", "topk_rank": 16 }, { "id": "corpus-346463", "score": 0.6905403137207031, "text": "I'm in the market for a lab diamond and was wondering about others' experiences shopping around and finding the right rock and vendor.", "topk_rank": 17 }, { "id": "corpus-1189715", "score": 0.6895578503608704, "text": "So a while back I was getting in my car in a parking lot and I saw what I thought to be a diamond on the ground near me. Of course I picked it up in hopes of luck. I've done some home tests such as scratching glass or seeing if it fogged when I would breathe on it. It has passed a few tests and failed none. Basically, given the backstory of how it was found, I was wondering what the best approach would be when taking it to a jewelry store.", "topk_rank": 18 }, { "id": "corpus-34156", "score": 0.6874326467514038, "text": "We have them. They make industrial diamonds for saw blades and the like quite frequently. We produce diamonds all the time through a variety of processes, though it only recently we have been able to make gem quality diamonds of size in the laboratory.", "topk_rank": 19 } ]

[ { "id": "corpus-325411", "score": 0.6527094841003418, "text": "[Any gases lighter than air](_URL_0_) EDIT: If you have the resources, and are actually going to try this, I would suggest avoiding flammable gases, such as hydrogen - think *Hindenberg disaster*" } ]

[ { "id": "corpus-314343", "score": 0.6200209259986877, "text": "Besides buoyancy, the main use of helium is to get things very cold. It has the lowest boiling point of any element (4 Kelvin), and liquid helium is basically the only thing that can get things much colder than that. One of the more common applications is in MRI machines in hospitals, where liquid helium is used to keep the superconducting wires in the magnet cold enough to keep superconducting.", "topk_rank": 0 }, { "id": "corpus-180084", "score": 0.6199154853820801, "text": "The interesting thing about the feeling of suffocation is that it's not triggered by a lack of oxygen, it's triggered by the *presence* of carbon dioxide. This is why it's so easy to accidentally pass out while breathing helium, and why liquid nitrogen in a closed space is so dangerous; there's almost no warning that you're about to lose consciousness, aside from your rapidly diminishing cognitive ability. The gas released from carbonated drinks is nearly pure carbon dioxide though, so when you breathe that in your body immediately thinks it's suffocating.", "topk_rank": 1 }, { "id": "corpus-687925", "score": 0.6198184490203857, "text": "Packages over 2kg cost more to ship where I live. Now if i would have to ship an item weighing a little bit over 2kg could I just add helium balloons to make it lighter or would that not work!", "topk_rank": 2 }, { "id": "corpus-98415", "score": 0.6197539567947388, "text": "[Helium is light. Lighter than air. When it's not contained, it rises into the atmosphere and is no longer in a usable state to us. According to VSauce, it gets picked up by solar winds and completely removed from our atmosphere.](_URL_0_) Helium is very cheap to use, and is used in a lot of places, and it's non-renewable. That means it's getting fairly rapidly depleted.", "topk_rank": 3 }, { "id": "corpus-276066", "score": 0.6197381615638733, "text": "According to the Wikipedias, it's because of its relatively low mass and low reactivity. Its negligible reactivity prevents it from forming compounds so the heat of planetary formation drove out almost all of it and it's light enough to float up out of the atmosphere to get stripped off by the solar wind. Helium is the same except that it's constantly being replenished on Earth via alpha particle decay.", "topk_rank": 4 }, { "id": "corpus-247526", "score": 0.6194972395896912, "text": "Wax is a very hydrophobic surface, so imagine what would happen if you threw a candle into water. It would float because it's less dense and the surface effect wouldn't change that. The same would be be true for you in a superhydrophobic suit.", "topk_rank": 5 }, { "id": "corpus-286281", "score": 0.619408369064331, "text": "I would imagine the mass of the release valve and mechanism to make it work would be counter productive. At 100,000 ft the density of the air is pretty low which the bouyancy force is proportional too. This means your balloon will only continue to rise as long as the mass of the balloon and containing air (plus valve) is less than the mass of the air displaced by the volume of the balloon. Coming up with a very lightweight system to do this is probably the limiting factor and challenge here. My own calculations: Right at bursting point your displaced mass at 100,000 ft is 1.483 kg. This means that if you can get the sum of your balloon, air inside, and valve to be less that 1.483 kg you could keep rising. I have no intuition at all for mass of balloon is normal and other things but you may have a better idea. [Bouyancy forces and equilibrium](_URL_0_) [air density](_URL_1_)", "topk_rank": 6 }, { "id": "corpus-167944", "score": 0.6193618774414062, "text": "Its probably a definition issue of freezing. What makes helium unique is that it can't \"freeze\" or be solidified under normal pressures on earth. You have to expose it to 2.5Mpa and a temperature of less then 1.5K (0K beeing absolute zero) so that would be around -271°C or -457°F.", "topk_rank": 7 }, { "id": "corpus-82130", "score": 0.6193422079086304, "text": "Water has air dissolved in it. When it's pressurized in pipes, it gets air forced into it. Most home sinks have aerators that mix in air when it's being poured. Even splashing it into a glass can add some air. Over time, these gasses come out of solution & form bubbles. Often, the bubbles form at the side of the glass where there's little imperfections ('nucleation sites') for the gas to stick to. It's not a lot different than a carbonated beverage except that the carbonated beverage has a *lot* more gas dissolved in it, so you get get streams of bubbles at the nucleation sites, growing large enough to float to the top.", "topk_rank": 8 }, { "id": "corpus-127123", "score": 0.6190384030342102, "text": "They get lighter. Helium tanks contain compressed helium, which is actually quite a bit heavier than air.", "topk_rank": 9 }, { "id": "corpus-275814", "score": 0.6189995408058167, "text": "The advantage of Helium and Hydrogen is that they exert outward pressure to counteract the inward pressure of the atmosphere, so the skin of the airship just needs to be strong enough to hold in the gas without leaking. However, an airship that used a vacuum would have to be **much** stronger (and therefore much heavier) to resist the inward force of the atmosphere. The added strength required would greatly offset the marginal benefit from having a vacuum.", "topk_rank": 10 }, { "id": "corpus-321103", "score": 0.6189529299736023, "text": "In water, that might be difficult. For example, oxygen is 600 times lighter at 1 bar, meaning that you'd need a pressure of about 600 bars to make it as dense as water. But of course, at that kind of pressure, it's a liquid. And don't try to compensate by increasing the temperature: you'd just get a supercritical fluid, not a gas. [Tellurium hexafluoride has a density of about 11 kg/m³,](_URL_1_) while [ether has a density of 70 kg/m³](_URL_2_). So, in theory, at 7 bars, the former is denser than the latter. I'm not sure what happens to TeF6 at that pressure though. And I really don't want to check myself: this stuff is nasty. Edit: [Xenon is lighter than TeF6 (6 kg/m³)](_URL_0_), but, as a noble gas, it might be able to stay gaseous at 12 bar. So, maybe it's a better candidate. Or maybe radon?", "topk_rank": 11 }, { "id": "corpus-321048", "score": 0.6183842420578003, "text": "Non-carbonated beverages may also have dissolved gases in them, albeit not as much as carbonated ones. The walls of the glass usually have impurities such as dust or even scratches on them that act as nucleation sites for the dissolved gases to grow on as bubbles.", "topk_rank": 12 }, { "id": "corpus-238913", "score": 0.6182080507278442, "text": "Back when I was at MIT (in nineteen mumble mumble), we made something we called a Hydrogen Bomb. It was actually a balloon with two parts hydrogen and one part oxygen (made in a chem lab). In the evening they were suspended from an outside balcony so they almost reached the level of the roof, but suspended from the West side of the building. When the sun rose (in the East) the next morning (over the level of the roof), the sunlight would hit the balloon and break apart one of the 0*_2_* or H*_2_* molecules, releasing two free atoms. The free atoms would then react with another molecule, releasing energy and possibly creating another free atom or two. This took less time than the description but the result was an explosion, creating the water, as you note. Most likely, the prevalence of free Oxygen in the air prevents much Hydrogen from accumulating. In fact, I would assume that it's vanishingly small, but don't quote me.", "topk_rank": 13 }, { "id": "corpus-18729", "score": 0.6181283593177795, "text": "Soda is stickier than water. Foam is the fluid sticking to escaping gas. Water slips off bubbles really easily but the soda doesn’t.", "topk_rank": 14 }, { "id": "corpus-271827", "score": 0.6181212663650513, "text": "From [ENRICO FERMI AND THE PHYSICS AND ENGINEERING OF A NUCLEAR PILE: THE RETRIEVAL OF NOVEL DOCUMENTS](_URL_0_ ) > to build the pile inside an envelope made of ballon cloth to remove the air (and replace it with Carbon dioxide), in order to minimize the absorption of neutrons by the nitrogen in the air within the pile, with a gain of about 1% in the reproduction factor [25, 5]. Although the balloon was planned to be filled with carbon dioxide, it ended up not being necessary because they were able to acquire purer metallic uranium.", "topk_rank": 15 }, { "id": "corpus-324690", "score": 0.6179968118667603, "text": "Helium is less polarizable than hydrogen (or H2) because its nucleus has double the charge, yet its electrons lie in the same shell. The same effect makes helium atoms smaller than hydrogen atoms.", "topk_rank": 16 }, { "id": "corpus-291666", "score": 0.6179799437522888, "text": "(_URL_0_) Basically all liquids have this ability. The only thing stopping them from doing this is their viscosity. Since superfluid helium has virtually no viscosity, its molecules can slide past each other with virtually no resistance allowing them to overcome gravity's downward force.", "topk_rank": 17 }, { "id": "corpus-322461", "score": 0.617855429649353, "text": "For the same reason it goes up in still air: its lighter/less dense than regular air. When the car accelerates, the heavier/denser regular air moves towards the back of the car by inertia, just the same way you feel pressed into your seat. The helium balloon wants to do that also, but the heavier air rushes past it and pushes the helium balloon forwards. Think of the back of the accelerating car as \"down\" and it should make more sense.", "topk_rank": 18 }, { "id": "corpus-274631", "score": 0.6178013682365417, "text": "The reason we fill blimps with gas is to equalize the pressure inside and outside. If you try to have a vaccuum blimp, you need to make it from a material that's capable of holding up against 101,250 newtons per meter squared of pressure. I don't know of anything that could do that for something the size of a blimp, especially without being heavier than that amount of vaccuum could lift.", "topk_rank": 19 } ]

[ { "id": "corpus-325412", "score": 0.7154426574707031, "text": "Perhaps the most famous astronomical discovery from an eclipse is Arthur Eddington's observation that the light of distant stars is bent by the gravity of the sun, as predicted by Einstein. They're also useful for seeing the spectrum of the solar corona, which is normally hard to see over the sun." } ]

[ { "id": "corpus-776652", "score": 0.6771751046180725, "text": "I keep hearing about so many important astronomical events that won't happen again for \\_centuries\\_ that I could be able to witness, and yet I can't, or I won't, probaly because I'm so used to seeing them online. Mainly to blame is the absurd light contamination I've always been used to, having lived all my life in a urban setting. I know it's simply a matter of me wanting to make it happen and doing it... but for this post I just wanna know if there's more peoplein this situation.", "topk_rank": 0 }, { "id": "corpus-237756", "score": 0.675163984298706, "text": "Astronomy in general. Amateurs with amateur-level telescopes find new and interesting things all the time. _URL_0_", "topk_rank": 1 }, { "id": "corpus-304598", "score": 0.6744236350059509, "text": "Yes. Since 2006 NASA is monitoring the Moon to record impacts. Most of them can be seen only through telescopes, but there has been one of magnitude 4, which is comparable to the dimmest stars visible to the naked eye. (Under appropriate conditions up to magnitude 6 may be visible.) _URL_0_", "topk_rank": 2 }, { "id": "corpus-324311", "score": 0.6736522912979126, "text": "Yes. > If a planet orbited two stars orbiting each other, eventually one would overlap the other from a set vantage point on that planet. As long as they were all in the same plane. If the planet was out-of-plane compared to the binary system, then obviously the planet would always see two stars. > Would the view from the planet be similar to a regular eclipse, or would the one appear brighter, or would it not really be noticeable? The total luminosity of the binary system decreases when one star is eclipsed by the other. > Do the types of stars affect the visual outcome? Of course. The brightness and diameter of each determine how the eclipse will appear. In the case of neutron stars, keep in mind they are tiny compared to main sequence stars. _URL_0_", "topk_rank": 3 }, { "id": "corpus-2062245", "score": 0.673226535320282, "text": "I'd like to do a lesson on eclipses. I have a delta kit (earth moon and sun), but I'd like to have some great understanding of the concept. I teach 7/8 science. This lesson is not my 8th grade. I'd appreciate any help I could get!", "topk_rank": 4 }, { "id": "corpus-130628", "score": 0.6710072159767151, "text": "Astronomers and other scientists that study outer space are interested in phenomena that occur in all parts of the night sky visible from Earth. As such they observe all the parts of the night sky they can. This does still leave us with some limitations, however. For example, a sizable chunk of our view of the wider universe is blocked out by [the disk of our galaxy](_URL_0_) that is so dense and bright that we can't really see through it.", "topk_rank": 5 }, { "id": "corpus-1907581", "score": 0.6682751178741455, "text": "I recently got my self a nice pair of 10x50 orion binoculars. As the Lunar Eclipse is almost around the corner, I’m wondering how to view it with my binos? As I know the sunlight can be very dangerous so I’m not sure if it’s safe to view it without some kind of a filter. Btw I live in Slovenia - Central Europe. Thanks!", "topk_rank": 6 }, { "id": "corpus-324470", "score": 0.6681562066078186, "text": "This is exactly the effect that was measured by Eddington and Davidson back in 1919 that make Einstein world famous. During a solar eclipse, when the Sun is dimmed, you can see the starlight near it. If you record the positions of those stars and compare them to their locations when the Sun isn't in the way, there is a bending of light or shift which occurs because of the Sun's gravitation. Here's some info about it with a diagram, * _URL_1_ The actual paper, * _URL_0_ And the even more impressive and related effect of the Einstein Ring, * _URL_2_", "topk_rank": 7 }, { "id": "corpus-299695", "score": 0.6680421829223633, "text": "Technically, you are not observing the stars; you are observing the photons they gave off many years ago. Thus, this act of observation has an effect on those photons, but not on the star.", "topk_rank": 8 }, { "id": "corpus-292100", "score": 0.6676579713821411, "text": "It absolutely is. And yes, it's noticeable! In fact, when Einstein proposed his theory of general relativity - now our best theory of gravity - a century ago, the first prediction of his which experiments confirmed a few years later was that during a solar eclipse, stars near the darkened Sun should be in slightly different positions than usual, because the Sun is bending their light. An even more dramatic effect of light bending is [Einstein rings](_URL_0_), when one galaxy bends the light of another galaxy, behind it, so much that it becomes a lensed ring. We even have used this lensing effect to find Earth-sized planets around other stars! Another effect is that gravity stretches light out, causing it to become redder. This is something we've also observed in labs on Earth.", "topk_rank": 9 }, { "id": "corpus-411724", "score": 0.6669671535491943, "text": "\"There’s a total solar eclipse happening on August 21, 2017, and for the first time in nearly a hundred years, the Moon’s unabashed Sun-blocking power will be visible from much of the continental U.S. (though certain locations will of course have a better vantage point than others). Warning: don’t look directly at it with your naked eyes—instead, use certified eclipse glasses or the pinhole method described here.\n\nIn the U.S., the eclipse will appear to move across the country from West to East, with the best view starting around 9:05 a.m. PDT in Lincoln Beach, Oregon, according to NASA, and moving southeast throughout the day to end around Charleston, South Carolina at 2:48 p.m EDT (enter your location here to find what time to look up).\n\nBut what if you are stuck in work that whole time, or something else is keeping you inside? Don’t worry, the internet has your back.\n\nNumerous organizations, including NASA, will be livestreaming the eclipse online for those of us indoor people. Below is a list of some of the main websites and apps you can use to stream this once-in-a-century astronomical sight. Just be sure you have Bonnie Tyler queued up and ready to go.\n\nDesktop: NASA TV Livestream Megacast (includes video from space, high-altitude balloons, and aircraft)\n\nAll Platforms: NASA TV YouTube (link to come)\n\nDesktop: NASA EDGE telescope views (toggle between 5 views)\n\nDesktop: Eclipse.Stream.Live (a.k.a. The Eclipse Ballooning Project, featuring footage captured by 100 high-altitude balloons from 55 teams of students around the country)\n\nDesktop: Astronomy.com\n\nDesktop: San Francisco Exploratorium website\n\niOS: Total Solar Eclipse app (from the San Francisco Exploratorium)\n\nAndroid: Total Solar Eclipse app (from the San Francisco Exploratorium)\n\nAll Platforms: Time and Date Livestream (in collaboration w/ Slooh)\n\nVirtual Reality: If you have the Samsung Gear VR app, Google Daydream VR app, or CNN VR app, you can watch CNN VR’s livecast of the eclipse in VR\n\nDesktop: Elephant Sanctuary in Tennessee (watch how the elephants react) \n\n", "topk_rank": 10 }, { "id": "corpus-833953", "score": 0.6667338013648987, "text": "So what if the star that we are observing has a star relatively close to it and it is behind it from our point of view. Could this star be larger and acting like an eclipse on the star behind it with sort of an overlap and the overlap becoming smaller as time passes.\nJust an interesting thought I was having.I know nothing about space but would something like that be possible to see if two Stars were close like that?", "topk_rank": 11 }, { "id": "corpus-213109", "score": 0.6664934754371643, "text": "I had a long answer typed up but the app crashed. I'll simplify for you. Late 500s, Gregory de Tours did lots of empirical observation and wrote \"The Course of the Stars\", which accurately contains records of eclipses and Comets. However, The key source for this period is the Anglo Saxon Chronicle. It's a gold mine record for astronomy in the time period. Here's a source that will answer all questions you have: _URL_0_ As an added bonus, Haley's comet showed up in 1066 and people at Hastings could allegedly see it.", "topk_rank": 12 }, { "id": "corpus-109316", "score": 0.6648504137992859, "text": "During the day, the simple pain from looking at the sun is usually enough to prevent you from staring at it too long. But during an eclipse, you can easily stare much longer at it even though a potentially harmful amount of radiation is still coming from it.", "topk_rank": 13 }, { "id": "corpus-832509", "score": 0.6627644896507263, "text": "How dangerous is it actually to view an eclipse without proper equipment? I know it's ill-advised. But is it ill-advised in the sense that jaywalking is ill-advised; or ill-advised in the sense that jumping into a lion enclosure is ill-advised? Surely there are thousands of people who look at solar eclipses without proper equipment every time one occurs (most don't frequent astronomy websites), and yet there isn't mass-blindness every time one occurs. And I've looked at the sun unprotected for short times before without causing any noticeable eye damage.\n\nI ask because I can't get the right equipment. I simply don't have that kind of money. So while I accept that taking a few quick glances at it with an ordinary pair of sunglasses does have some risks, I'd like to have some rational idea of exactly what those risks are that's a bit more nuanced than \"It's dangerous. Don't do it.\"", "topk_rank": 14 }, { "id": "corpus-283274", "score": 0.6618324518203735, "text": "Yes. The less atmosphere you are looking through the less distortion you see. That's why observatories are located on mountain tops or in space (as in the Hubble).", "topk_rank": 15 }, { "id": "corpus-194418", "score": 0.6603646278381348, "text": "As a follow up question, I know I've certainly looked at the sun directly many times, and as far as I can tell I can see just fine still. Why is looking at an eclipse more dangerous?", "topk_rank": 16 }, { "id": "corpus-202559", "score": 0.6598526239395142, "text": "I don't know a specific answer, but it will almost certainly be an astronomical event that we can, with modern astronomy, calculate when it must have been, instead of somebody mentioning that something happened on a day, and we know enough about that calendar to figure out when that day was in our own calendar. Eclipses happen rarely enough to be commented on, but so regularly that we can figure out all of them have happened in the last X thousand years, and predict them for the next X thousand years, too. Also comets that come around regularly (specifically Halley's) are often mentioned. I don't know if those count as \"historical events\" for your question, but they're the sort of thing that might be seen as a sign from the gods, and therefore influence peoples' actions.", "topk_rank": 17 }, { "id": "corpus-1420311", "score": 0.6576966047286987, "text": "So first of all, I know that many of us don't pay too much attention to astronomy and stuff outside of spell work, but I am a pantheist, and I've always felt a strong connection to the universe and space as a whole, not just nature. There is going to be a lunar eclipse tomorrow night, and there will also be a comet! I'm really excited, but at the same time, I'm not sure how to celebrate it. I have a friend who is having a hard time with her health, so I was thinking of doing a ritual for her, since she could really use the support. \nAll of this in mind, can anybody direct me to some guides regarding this, or share ideas?", "topk_rank": 18 }, { "id": "corpus-832609", "score": 0.6576006412506104, "text": "Hey all. I'm located in Oxford, Mississippi, about a 5 hour drive from close to the center of the eclipse (Nashville area). I'm debating whether I should skip my first day of classes to travel to the center of the eclipse. I'm wondering how different the viewing experience is for a *total* eclipse compared to the partial I will experience in Oxford. Accoring to this website, the sun will be almost completely covered. Will I notice a significant difference?", "topk_rank": 19 } ]

[ { "id": "corpus-325413", "score": 0.8131064772605896, "text": "Helium, a noble gas, is too light to be held under earths gravity. Hydrogen is lighter, and free hydrogen will also escape, however, it is also reactive, and unlike helium, is mostly bound up in compounds with other elements. Free hydrogen will still escape." } ]

[ { "id": "corpus-246060", "score": 0.7723405361175537, "text": "We lose some hydrogen to space, we gain a little bit of oxygen from asteroids and dust that hit Earth. Both elements are found in a large range of molecules so the effect on the amount of water is not immediately clear but the loss of hydrogen should be more important: We slowly lose a bit of water.", "topk_rank": 0 }, { "id": "corpus-294371", "score": 0.7717978954315186, "text": "We lose about 3kg of hydrogen and 50g of helium each second (about 10^8 per year) due to [Jeans escape](_URL_0_). _URL_1_ We also gain 10^7 to 10^9 kg per year due to meteorites and such. _URL_2_ It balances out (to some degree). EDIT: Added a source.", "topk_rank": 1 }, { "id": "corpus-98415", "score": 0.7674759030342102, "text": "[Helium is light. Lighter than air. When it's not contained, it rises into the atmosphere and is no longer in a usable state to us. According to VSauce, it gets picked up by solar winds and completely removed from our atmosphere.](_URL_0_) Helium is very cheap to use, and is used in a lot of places, and it's non-renewable. That means it's getting fairly rapidly depleted.", "topk_rank": 2 }, { "id": "corpus-276066", "score": 0.7664890885353088, "text": "According to the Wikipedias, it's because of its relatively low mass and low reactivity. Its negligible reactivity prevents it from forming compounds so the heat of planetary formation drove out almost all of it and it's light enough to float up out of the atmosphere to get stripped off by the solar wind. Helium is the same except that it's constantly being replenished on Earth via alpha particle decay.", "topk_rank": 3 }, { "id": "corpus-318463", "score": 0.7645398378372192, "text": "Because Helium is the second lightest element, behind Hydrogen, it is lighter than air. We lose Helium by it escaping the atmosphere. Helium is generated through the radioactive decaying of minerals such as, uranium, thorium and monazite along with a few others that I know of. Sources: _URL_0_ Under Occurrence and production, 2nd paragraph _URL_1_", "topk_rank": 4 }, { "id": "corpus-168813", "score": 0.7642718553543091, "text": "Earth's gravity isn't strong enough to hold onto helium in the upper atmosphere, so once it gets up there it will eventually escape into space and be blown away by solar winds. And the helium in the atmosphere is so dispersed you would have to filter tons and tons of air before you could extract enough helium from it to be usable, and the entire time you are trying to extract it, you will be using energy that needs to be paid for.", "topk_rank": 5 }, { "id": "corpus-109102", "score": 0.7607307434082031, "text": "Helium is a very small atom, just two protons. Only hydrogen is smaller. It seeps out through the mylar\\rubber that makes up the balloon itself and escapes into the atmosphere. That's why helium balloons start to sag after a while, there's less gas pressure inside.", "topk_rank": 6 }, { "id": "corpus-324944", "score": 0.7601225972175598, "text": "It gets spewed out by the sun, and when it reaches the moon it gets embedded in the soil but when it reaches the Earth it circulates through the atmosphere, moves around through geological and meteorological processes, etc and any helium in the upper layers of the soil would quickly be loosed by erosion. The main difference is that helium-3 is lighter than helium-4 (the regular kind), and also more technical differences like it's a fermion and He4 is a boson.", "topk_rank": 7 }, { "id": "corpus-319079", "score": 0.7600525617599487, "text": "Helium does indeed escape out the top of the atmosphere and is continuously being lost to space. The atmosphere contains essentially no helium and the only sources (used for balloons, medical equipment, etc) is found buried and trapped in the earth. Our current helium sources are usually associated with oil and gas wells. Once that helium is used up it will become [very difficult to replace.](_URL_0_)", "topk_rank": 8 }, { "id": "corpus-303666", "score": 0.7599998712539673, "text": "The ambient temperature induced movement of the atmosphere is enough to mostly keep them all well-mixed. Think wind and the actions of precipitation as brought about by continuous solar heating of the air. But a little bit of what you are suggesting does happen to a significant degree. Helium and hydrogen are very light gases that tend to find their way into the upper atmosphere and escape into space sufficiently such that free molecules are relatively rare on Earth despite them being the most abundant things in the universe. Hydrogen isn't hard to produce (by electrolysis of water for example). But Helium as a byproduct collected during mining of other resources isn't produced in very much quantity. There has been talk of a helium shortage for some time now in the US.", "topk_rank": 9 }, { "id": "corpus-136651", "score": 0.7568913698196411, "text": "There are pockets of it underground. When these are discovered, it's pumped out and put into containers. It's typically found mixed with natural gas, and there are ways of filtering it out. Helium that escapes into the atmosphere is gone for good. Back in the day when it was thought that lighter-than-air craft would have a place in wartime, the U.S. government started stockpiling it. This was the [\"National Helium Reserve\"](_URL_0_).", "topk_rank": 10 }, { "id": "corpus-249072", "score": 0.7560155391693115, "text": "Someone else may have to correct me on this, but I believe this is related to the Joule-Thomson effect, where helium and hydrogen have anomalous behavior, being very much non-ideal gases. I don't remember enough about the topic offhand to go into it in detail, but I'd read up on the [Joule-Thomson Coefficient](_URL_0_) for at least a hint as to why hydrogen and helium are unusual.", "topk_rank": 11 }, { "id": "corpus-80337", "score": 0.7521947622299194, "text": "You know how when you inflate a balloon it stretches out? This is because all the air molecules inside are banging around against the walls of the balloon. In space, it would be the same story, except you don't have any walls to stop it. So your 'bubble of air' would expand outwards and quickly become extremely thin and indistinguishable from the normal background of space. The difference in a place like Earth, is that there is so much mass here (of which the air is a part) that the gravitational pull keeps the air from flying away, for the most part. It's unable to achieve escape velocity. Even so, hydrogen and helium from earth do constantly achieve escape velocity, and so we are gradually losing it to the universe, but at such a slow rate (relative to the total volume) that we don't really notice.", "topk_rank": 12 }, { "id": "corpus-92594", "score": 0.7521376609802246, "text": "Gravity keeps most of the atmosphere contained. However, if an air molecule gains enough speed through a series of collisions, it can escape earth's gravity and into space. This is much easier for lighter elements like Hydrogen and Helium. For heavier gases, like the nitrogen and oxygen that make up the majority of the atmosphere, these losses are very low compared to the total mass of the atmosphere.", "topk_rank": 13 }, { "id": "corpus-145065", "score": 0.7512488961219788, "text": "Helium is extracted from natural gas, kind of like how gasoline is extracted from petroleum (oil). It won't float away because it is PART of the natural gas. Since it is extracted in a controlled environment it can be separated from other products, like butane (think cigarette lighters) and propane (think gas BBQ grills). Each product is removed at a particular fracking stage and stored into separate tanks. this is an oversimplified explanation...but this is ELI5. You can google fractional distillation or wiki it for the science(y) details of how the process works.", "topk_rank": 14 }, { "id": "corpus-1553582", "score": 0.7505370378494263, "text": "Helium is lighter than air so it will all be blown off the atmosphere sometimes. But it is also constantly created during radioactive decay and therefore is found in natural gas deposits. Our lab is using two 50L tanks of helium (220 bar) in one and a half week. Frequently we fail to get enough gas and need to shut down some of the instruments. I used to say the Large Hadron Collider for responsible for the shortcoming. I'm not sure if it's still valid. Does anyone else here have the same problem? Is there really a helium crisis?", "topk_rank": 15 }, { "id": "corpus-134151", "score": 0.7496390342712402, "text": "Gravity. That being said some particularly light gasses do escape into space like helium.", "topk_rank": 16 }, { "id": "corpus-2385779", "score": 0.749491810798645, "text": "I've read that Helium is distilled from natural gas and most of the supply is in Texas. So after Helium gets used it goes into the air. Is that all that is happening? Helium is a noble gas so it won't react. Can Helium escape the pull of gravity? I would think the gravity and buoyancy would equalize before atmospheric escape (I may be wrong). \n\nIf this is true, it is not that we are running out of helium, it's that the atmosphere is full of Helium and we just don't know how to collect it yet.", "topk_rank": 17 }, { "id": "corpus-97068", "score": 0.7487691044807434, "text": "It's not burning like a fire. Hydrogen is being fused into helium, this requires high temperatures and produces a lot of energy.", "topk_rank": 18 }, { "id": "corpus-311775", "score": 0.7487300634384155, "text": "It is not fighting gravity. It is just lighter than the air around it. The air is pushing it up, much like air bubbles rise in water. Space is a vacuum, so it depends on it's initial course. If the helium escaped Earth's atmosphere it would not keep 'rising'. Earth's gravity would still pull it. But in a zero G vacuum it would travel (or be stationary) until something else acted upon it.", "topk_rank": 19 } ]

[ { "id": "corpus-325414", "score": 0.8149237036705017, "text": "You're going to have to clarify your question a bit. When you get sunburned, the damaged skin goes away and is replaced by new/healthy skin." } ]

[ { "id": "corpus-108135", "score": 0.7584984302520752, "text": "only the outer layer of skin replaces itself ... thats why tiny scratches heal without scars but go any deeper and the body has to do a rush job just to keep you alive .... and rushed jobs never look pretty", "topk_rank": 0 }, { "id": "corpus-68222", "score": 0.7584237456321716, "text": "Our skin usually replaces itself slowly at all times, when you get sunburnt your skin cells get damaged, they either die or go through apoptosis (programmed cell death) to avoid developing into cancer or disrupting other cells, and your body has to replace them faster than usual. The skin that peels off is just dead skin.", "topk_rank": 1 }, { "id": "corpus-158706", "score": 0.752948522567749, "text": "The thing that everybody believes about skin being \"constantly regenerated\" isn't exactly true. Your skin is made up of five different layers. Blemishes are located in the lower layers. It's only the top layer (the epidermis) that falls off and is replaced. It's the same layer that peels off when you have a sunburn.", "topk_rank": 2 }, { "id": "corpus-129045", "score": 0.7446253299713135, "text": "Short answer: The same way bad haircuts do. Longer answer: The human body is an amazing bit of engineering. It's constantly repairing itself, protecting the more vital organs from harm, and adapting to the environment as best it can in a way that human beings haven't even come close to replicating with technology. The sunburn isn't 'disappearing' it's just that the damaged and burned skin cells are sloughing off (as skin cells tend to do) and being replaced by new, healthy skin. The worse the sunburn, the more damaged tissue that needs to be replaced, thus, the longer it takes for a 'sunburn' to heal.", "topk_rank": 3 }, { "id": "corpus-149049", "score": 0.7392849922180176, "text": "Because your body doesn't fully heal. It covers the area with tough collagen fibers, and the skin tissue does not grow to replace it.", "topk_rank": 4 }, { "id": "corpus-53256", "score": 0.7339591383934021, "text": "Imagine your skin as the walls of a house. Normally, there is some wear and tear from the weather on the sides of the wall but you can always replace the paneling or repaint the outsides (epidermis). However, one day, a drunken driver crashes into the side of your house and leaves a big hole. You have to patch up the hole quickly (scar) to make sure that all the bad elements from the outside don't get inside your house. You can still cover up the hole with new paneling and paint (the epidermis regenerates) but all the wiring and insulation (dermis) that was originally in the wall is gone. It's in the dermis that contains the cells that will create melanin when exposed to sunlight. The melanin is what makes your skin tan.", "topk_rank": 5 }, { "id": "corpus-187176", "score": 0.733948826789856, "text": "Because with a scar you have damaged the deeper layers of skin where the new skin is being formed. Your skin has to try and fill in the void created by the injury and does so in a way that effects the new skin that will eventually be there.", "topk_rank": 6 }, { "id": "corpus-308933", "score": 0.731454074382782, "text": "Humans sweat and rub their skin. Over time the sun screen is either absorbed or rubs off. Aside from that, it doesn’t fully block UV light; only enough so that the skin can repair any damage inflicted. Over time, the damage due to exposure increases past the point your skin can safely handle.", "topk_rank": 7 }, { "id": "corpus-120924", "score": 0.7291316986083984, "text": "the ultraviolet light from the sun is invisible, but high-energy. it can actually hit your genes inside the skin cells and knock them all wonky. if it doesn't kill them outright, they can make bad copies of themselves. some of these bad copies might be cancerous. scrapes and bruises are mechanical damage to the tissue, but don't get inside the cells and change the dna in the genes.", "topk_rank": 8 }, { "id": "corpus-22248", "score": 0.7285201549530029, "text": "So basically, our bodies make more skin by having the old skin cells make new ones. Young people’s cells are in perfect condition, so the new cells are in tip top shape. The older you get, you have damage from the sun and that sort of thing - so the skin cells aren’t able to make new skin as well as they used to. I hope this helps. I’m sure someone else will be able to explain it better.", "topk_rank": 9 }, { "id": "corpus-191116", "score": 0.7278291583061218, "text": "The same way we still have regular skin which acts differently in various locations (such as hair growth in some places and no hair in others)— it gets replaced with the same type of cell that is programmed to act the same way. Some of these things may seem like “flaws” (cosmetically or otherwise) but they are just following the body’s chemical signaling, or genetic makeup of the cells in that location. As far as the replacement cells are concerned you are “supposed” to have a freckle there so it stays. And when it comes to scars— they form during the (relatively fast) healing process when it may not be possible to fully, or quickly rebuild the underlying structure with the same circulation, muscle tissue, nerve tissue, etc to restore the original appearance and function... so scars can fade over time but there are good reasons why they persist and take a long time to heal.", "topk_rank": 10 }, { "id": "corpus-159798", "score": 0.7250362634658813, "text": "It's a myth that you replace all your cells after so-and-so many years. The most important cells in your body — neurons and osteocytes — stay with you for life. But getting back to the question, the reason why scars don't usually disappear is because the skin that was lost gets replaced by a *different kind* of tissue altogether. Basically, in normal skin the microscopic structure of the tissue is such that it's kind of like a *weave,* sort of. In scar tissue, on the other hand, the fibers are mostly aligned. The net result is that the scar tissue is very different from the skin it replaces. As you age, that scar tissue stays with you. The individual cells in your skin die and slough away, yes, but the larger-scale *structure* of the tissue remains the same. Kind of like replacing every brick in a building one at a time but leaving the walls where they are.", "topk_rank": 11 }, { "id": "corpus-60739", "score": 0.7243550419807434, "text": "Your skin contains several different types of cells. The skin cells you're thinking of that regenerate and slough off every so often are called keratinocytes. The cells that make up moles/birthmarks are a different cell type called melanocytes. Melanocytes do not get replaced by keratinocytes. As far as cancer goes, the skin regeneration is the problem! UV light causes damage to cells by forming abnormal linkages in the DNA. Often this damage can be corrected, but the more UV exposure, the more damage that occurs. If it cannot be corrected, then it is possible that certain regions in the DNA are not read correctly during replication. Some mutations can cause this new cell to become immortal, and it will keep on replicating. This abnormal growth is cancer.", "topk_rank": 12 }, { "id": "corpus-12788", "score": 0.7241974472999573, "text": "Because the regrowth is not perfect, the body also needs to grow until its twenties, and because wrinkles are not affected by replacement. A wrinkle is like if you squished a cloth a bunch of times, it would have wrinkles and replacing all the individual threads of the cloth would NOT make the wrinkle go away, because everything had already been bent into shape.", "topk_rank": 13 }, { "id": "corpus-246858", "score": 0.7233909964561462, "text": "This is not my field of expertise, so I'll keep my comment brief. Consider 2 groups. Group A gets 3 minutes of exposure to the Sun each day for 100 days consecutively. Group B gets no exposure to the Sun for 99 days, then is exposed for 300 consecutive minutes on the 100th day. Clearly, it's not entirely linear. The body obviously has some healing ability that can, given time, counteract damage done to it.", "topk_rank": 14 }, { "id": "corpus-163899", "score": 0.7209891676902771, "text": "Skin has living cells which can react to incoming UV light by producing more protective melanin. Hair does not have any living cells, so whatever pigment it has is broken down by UV light and can't be replaced.", "topk_rank": 15 }, { "id": "corpus-189739", "score": 0.7202908992767334, "text": "Skin is constanly dying an being shed. If there is no more sunlight triggering tanning, the new skin won't be as tan.", "topk_rank": 16 }, { "id": "corpus-171266", "score": 0.7183859348297119, "text": "Scars don't have, or produce melanin, because they're areas of fibrous tissue (from my understanding, just not fully healed tissue). It's also the reason why they have no hair follicles or sweat. Complete regeneration takes a really long while as well. When skin tans, it's because it's essentially your skin adapting to the short-term high amounts of sunlight hitting your skin; in particular UV light attacking the epidermis and causing more melanin to be generated. Scars lack this, because they're an unorganized layer of collagen in the skin, while normal skin is neatly organized in layers. Although this is a bad example, think of scars like welding a large hole in an otherwise complex machine. Something that'd cause the machine to do something if touched wouldn't happen on contact with the welded hole because it's just unorganized metal that sloppily covers the machine, as to prevent things to enter it and mess things up before the mechanic can fix it properly.", "topk_rank": 17 }, { "id": "corpus-107615", "score": 0.7171451449394226, "text": "The sun doesn't actually burn you, it causes DNA damage at the cellular level. When the damage is detected, the cells begin to commit suicide to prevent the mutated cells from reproducing. The redness is caused by increased blood being provided to the area to take away the damaged cells and help the healing process. It takes some time for the cells to detect this mutation and cause the cells to die off, thus the delay noticing the burn.", "topk_rank": 18 }, { "id": "corpus-50077", "score": 0.7160860300064087, "text": "The actual sunburn is an inflammation **response**. The skin cells exposed to sunlight get so much DNA damage that they will go through cell death rather than risk replicating the damaged DNA. The large amount of dead cells and cell matter activates the inflammation response so the body can clean up the mess and it doesn't poison the surrounding living cells. The inflammation response is a combination of swelling to promote blood flow, heating up to make the immune cells work faster, and movement of macrophages like white blood cells to the area to help consume the mess. This is why sunburns become red, hot to the touch, and slightly swollen. If the tissue was not alive, the immune response will not active and thus, you won't experience the inflammation response that causes sunburns.", "topk_rank": 19 } ]

[ { "id": "corpus-325415", "score": 0.8105044960975647, "text": "Nope! Not as it is naturally. In the book (which is fantastic, by the way), Mark Watney actually adds fertilizer (poop) and water to the soil, so it's not as simple as it seems in the trailer. That said, plants still wouldn't grow in Martian soil in reality. I'm no botanist, but one major problem with the soil on Mars is that it's covered in perchlorate, an extremely reactive (ie explosive) oxidizer, which is toxic. I'm sure there are other problems as well..." } ]

[ { "id": "corpus-299405", "score": 0.7662031054496765, "text": "Yes, and in fact on the next Mars rover, [there will be an instrument that will convert CO2 into O2 in a technology demonstration in preparation for human exploration](_URL_0_). The problem with plants on Mars would be the soil moreso than the atmosphere. The Phoenix mission I worked on did some experiments with the regolith to determine composition, pH, etc. and at first they thought it would be suitable for planting things, but the discovery of perchlorates has complicated that.", "topk_rank": 0 }, { "id": "corpus-316824", "score": 0.7580618858337402, "text": "[This article](_URL_0_) goes in depth on the subject. The short answer is no you cannot just plant a tree on mars. There is not enough nitrogen. However, if you compensate for that problem, it may be doable, however there may be poisonous perchlorates in the martian soil that would kill your tree.", "topk_rank": 1 }, { "id": "corpus-324815", "score": 0.7529376745223999, "text": "No known species of plants would be able to survive direct exposure to the Martian conditions, such as extremely low temperature, thin air, high levels of solar radiation, and low amount of minerals and nutrients in the Martian soil. However, scientists are working on removing useful genes from extremophiles through gene splicing and adding them to plants, which could then be housed in little greenhouses on Mars. See more [here.](_URL_0_)", "topk_rank": 2 }, { "id": "corpus-552234", "score": 0.746696412563324, "text": "There's been a lot of talk about how future settlers will adapt Martian regolith to farming, but odds are this kind of farming isn't optimal for Mars. Just because planting things in dirt is conventional on Earth doesn't mean it'll be just as easy on Mars.\n\n1. Efficiency:\n * While figures vary depending on the specific plant, hydroponics can yield 4x more plant matter per farming area per year for less than 10% the water than conventional farming. A big part of the water inefficiency in conventional is that all the soil must be hydrated. You're not just feeding the plants.\n * Hydroponics is massively more energy intensive. ~80x the required light intensive.\n2. Infrastructure/scalability:\n * An obstacle to widespread hydroponics use on Earth is that conventional farming is easier. Putting seeds in the ground, fertilizing it, and letting nature do its thing vs building infrastructure for every plant you can accommodate; which way would you rather feed millions of people?\n * Farming on Mars, unlike Earth, will reqire infrastructure in either case. While hydroponics obviously requires plant housings, plumbing, water recycling, and lots of indoor space; conventional-style soil based farming on Mars requires washing regolith of perchlorates, fertilizing it with bioaccessible nitrogen and minerals, colonizing the intended soil with bacteria and fungi that associate with plant roots (helping nutrient uptake), putting all of this soil on top of a constructed floor (air and water would rapidly be lost to diffusion if a dome was just put over open soil), running water collection plumbing under all this soil (for recycling), running a watering system over the top.\n * Both hydroponics and soil based farming will need artificial lighting. *Try shielding the plants from too much radiation while keeping the ceiling transparent.* So hydroponics' increased lighting requirements won't require more lighting infrastructure, but more power production capacity.\n\nTL;DR: it looks like conventional-style farming will reqire all the infrastructure of hydroponics *plus* a lot extra. With the exception of being a power hog, hydroponics on Mars looks easier than soil based farming.\n\nE: formatting.", "topk_rank": 3 }, { "id": "corpus-309818", "score": 0.7395626306533813, "text": "It would be possible, it would just take a while. Adding gas isn't the problem; we do it all the time here on earth with global warming and such. Once you have enough CO2 in the atmosphere, add plants to get oxygen. The problem is that pesky solar radiation. Mars doesn't have a protective magnetic shield like Earth has, so the constant radiation would beat the atmosphere into space.", "topk_rank": 4 }, { "id": "corpus-289731", "score": 0.7387450933456421, "text": "Plants are very finicky. While having them in space would be the most logical way to produce life support, it is difficult because of a lack of gravity. While we have been able to grow sunflowers aboard the ISS, the lack of gravity showed some problems in their development. Plants require gravity to tell then which direction their roots should grow. Obviously, down means soil. Without gravity, plants become lost and will have more difficulty growing, resulting in limp produce. While there has been some success, growing plants in space is still unreliable, but will improve in the near future.", "topk_rank": 5 }, { "id": "corpus-322400", "score": 0.7380944490432739, "text": "The main problem I can foresee is the lack of nitrogen in martian substrate. There are many various plant species that can prosper with a lack of certain nutrients that others demand.", "topk_rank": 6 }, { "id": "corpus-1659883", "score": 0.735651969909668, "text": "Let me set the stage for this scenario. Let's imagine that (poof) Mars has a habitable, human-breathable atmosphere that's similar to Earth's atmosphere. Mars is now an M-class planet. Choose whatever method you like; oxygen factories, algae, asteroids, giant alien machines melting underground ice reserves and popping eyeballs, etc. The point is the atmosphere exists. Also, there's weather, mild seasons...everything is there for this planet to survive in this state for a long time.\n\nAlso, let's imagine that there is enough Martian plant life to maintain that atmosphere. These plants would be Earth plants that have thrived on Mars. Mars would look more like Pandora or a primeval Earth, with no shortage of healthy ecosystems. \n\nI'm well aware that the solar winds blew away the real Martian atmosphere long ago. But, if the above scenario was real, could Mars keep its breathable atmosphere? Or (whether it took 100 years or a billion years) would the atmosphere get blown away again by the solar wind? Could the Martian plant life produce enough oxygen to maintain the Earth-like atmosphere to counteract the solar wind's effects?", "topk_rank": 7 }, { "id": "corpus-2200196", "score": 0.7330597639083862, "text": "TIL about a neat company called 'The Martian Garden.' It was started by two friends who were both \"passionate space enthusiasts.\" They came up with the idea for Martian Garden Kits in 2015, and through a Kickstarter campaign in 2016, they were able to sell their first 50 kits. The soil (Mars Mojave Simulant or MMS) is based on original NASA/JPL research, and simulates the surface of Mars. You can buy two types of MMS soil and/or Martian Garden Kits on their website. \nYou can read more about how the company started here:\n \nYou can visit The Martian Garden website and webstore here: ", "topk_rank": 8 }, { "id": "corpus-775812", "score": 0.7214230895042419, "text": "Basically, if we put any species of earth life on Mars, is there any possibility that some kind of Earth life would be able to survive?", "topk_rank": 9 }, { "id": "corpus-322138", "score": 0.7190800905227661, "text": "At a microbiology conference I went to recently, there was a graduate student working on a project where he trekked all the way to the top of the highest peak in the Andes, on the assumption that conditions there would be similar to those on Mars. He took soil samples at various altitudes, brought them home to his lab, and spread them out on petri dishes containing growth medium. As I recall, he had growth from all the samples except for the very top of the peak. This doesn't really answer your question, but it is interesting experiment to try to find the answer to your question without actually going to Mars. Also note this is a very preliminary experiment with a lot of variables to account for (type of nutrient plate, contamination of samples during transfer, etc.).", "topk_rank": 10 }, { "id": "corpus-180847", "score": 0.7179136872291565, "text": "You could, but you would have to take some things into account, most of which could be solved reasonably easily: 1) as plants do their thing, they lose water from their leaves and transfer it to the air (called transpiration). This would reduce the amounts of water in the hydroponic reservoir. As plant on Mars would be in a closed system though (greenhouse for example), you could use a dehumidifier or something of the like to reharvest this water from the air and return it to the reservoir. 2) certain waste products would gradually build up in the water as it gets recycled. These could end up being toxic to the plants. Using a very good filtration system, you could return the water to its original purity periodically or even in line. 3) every time a plant is harvested, unless you dehydrate it totally and return that water to the system, you will lose some as you take it out as food/biomass. Other than that, water is water. You can totally use the same water indefinitely in a closed system.", "topk_rank": 11 }, { "id": "corpus-313880", "score": 0.716894268989563, "text": "Yes. In fact, the reason Mars is \"the red planet\" is because it's already covered in a thin layer of iron oxide powder -- rust dust! While Mars doesn't have atmospheric oxygen, radiation from the sun breaks up carbon dioxide and water to form peroxides in the soil. These are super-oxidizing chemicals that should cause rust pretty effectively. Might take a while, though. _URL_1_ _URL_0_", "topk_rank": 12 }, { "id": "corpus-324786", "score": 0.7122898697853088, "text": "From [wiki](_URL_0_) \"Actual temperature measurements from the Viking landers range from −17.2 °C (1.0 °F) to −107 °C (−161 °F).\" Which suggests that it very rarely makes it above zero. I'm guessing the answer is therefore no. But it would be interesting to know whether, if placed in a \"greenhouse\" like structure, possibly with heating, could earth's plants survive in the atmosphere of mars? (and therefore be able to produce oxygen for us to live)", "topk_rank": 13 }, { "id": "corpus-29070", "score": 0.7084965705871582, "text": "Production of an oxygen molecule via photosynthesis requires a water molecule. Algae farms like this probably will play a crucial role in making Mars habitable, but first we need to get the temperature up it gets down to 150 below on Mars. If we could boost the temperature a bit Mars would go into a self sustaining global warming, and all of the ice on Mars would begin to melt (there's quadrillions of tonnes of water on Mars its just locked away as permafrost), once that happened plants like these could be turned loose on to the planet to do their thing.", "topk_rank": 14 }, { "id": "corpus-290634", "score": 0.7057850956916809, "text": "Yes, plants are able to grow in zero gravity, but the precise effects on their growth are still an area of active research (i.e. on the ISS). _URL_0_", "topk_rank": 15 }, { "id": "corpus-312265", "score": 0.7054622173309326, "text": "[Chroococcidiopsis](_URL_0_) comes to mind: > Due to its resistance to harsh environmental conditions, especially low temperature, low moisture, and radiation tolerance, Chroococcidiopsis has been thought of as an organism capable of living on Mars.  As other commenters have said, the lack of water on Mars would probably prevent these guys from growing on their own. But with a little human intervention, they may be able to grow in Martian soil and help with the terraforming process (assuming we ever terraform Mars). Edit: for anyone interested in a great vision of colonizing and terraforming Mars, I highly recommend the Mars trilogy (Red Mars, Green Mars, Blue Mars) by Kim Stanley Robinson!", "topk_rank": 16 }, { "id": "corpus-1335938", "score": 0.7049145102500916, "text": "Okay weird question i know. \nBut lets say we build giant domes on Mars and is able to heat up the ground, to such a temperature that you can walk barefoot on the soil of Mars. \nWould it feel any different lets say walking on sand here on Earth, also how would mars smell compared to Earth? \nI think i read somewhere that the chemical composition of martian soil would make Mars smell quite sour, but if so what would be the closets analogy on Earth to the smell of Mars??", "topk_rank": 17 }, { "id": "corpus-644497", "score": 0.7047848701477051, "text": "I mean, we have studied Mars soil samples for more than 10 years and we haven't found any sign of life there. And terraforming could take an incredibly long time, so the sooner we start, the better.", "topk_rank": 18 }, { "id": "corpus-281550", "score": 0.7033742070198059, "text": "Its not the composition of the Martian atmosphere that matters, it's the atmospheric density. Atmospheric pressure is so low on Mars that nothing could grow. From Wiki: > mean surface level pressure[for Mars] of 600 pascals (0.087 psi), compared to Earth's sea level average of 101.3 kilopascals (14.69 psi),", "topk_rank": 19 } ]

[ { "id": "corpus-325416", "score": 0.714738667011261, "text": "You're neglecting the high pressure of air inside the tire that keeps the tire bead seated into the rim. All that pressure squeezes the rubber tire against the metal rim and greatly increases the friction between the two." } ]

[ { "id": "corpus-94074", "score": 0.6789267063140869, "text": "On top of the weight distribution factor, if you lost traction in the back wheels, your steering ability is now almost completely useless, because the part of the car that you actually control has no power. If you have front wheel drive, then at least if you get into a skid, you can point your wheels the direction you want to go and supply them exactly as much power as you want.", "topk_rank": 0 }, { "id": "corpus-1965469", "score": 0.6788345575332642, "text": "So you know how you have a car on a lift and you shake the front wheels side to side and up and down to test hub and tie rod ends? Well I did the other day and normally the wheel/steering doesn't turn with you, but this one did with a little force. I don't recall it being easy to do before.\n\nThere does appear to be some side to side play in both front wheels, but what are the chances of 2 tie rod ends going out at the same time? Even so, I don't think I should be able to turn the steering from outside the car. It's a 2002 Cadillac DeVille dts if that helps.\n\nWhat does this mean? It drives fine so I doubt anything is wrong with the steering shaft.", "topk_rank": 1 }, { "id": "corpus-274471", "score": 0.6787672638893127, "text": "The rotor still has to be supported by bearings which means there are still moving parts rubbing against each other making sound. Also, I don't know so much about electric cars, but industrial electric motors often have a fan attached to the rotor for force air through the motor to cool it down and so the spinning fan makes noise as it sucks air through the motor.", "topk_rank": 2 }, { "id": "corpus-52125", "score": 0.6787163615226746, "text": "When a bike is moving the wheels will have a gyroscopic force that resists \"sideways\" tilt movement. In this video, you can see Tim Peak demonstrating a gyroscope in space. When it's spinning, you can easily move it in any direction rather freely, but it's difficult to get it to \"tilt\" unless you physically reposition it or apply a significant force. It won't tilt under it's own weight. _URL_0_ It's the same with a bicycle wheel. As it's spinning, it will resist a tilting motion (to some extent), which helps you keep balance.", "topk_rank": 3 }, { "id": "corpus-1963524", "score": 0.6787034273147583, "text": "The problem began last year. I had winter tires on the car, on the stock wheels, no problems up to this point. I swapped the tires for the stock all-seasons, (by this point, I had approx 12,000 miles on the car, about 6,000 on the stock tires. It currently sits at 22,300 mi) and the day I left the shop (general mechanic), it started to shake at highway speeds, mostly around 65-75 mph. \n\nShortly after, I took the car to a tire specialist, who said all four wheels were out of balance, and one of my wheels was bent (I don't remember hitting any potholes, but I live in PA, so I can't rule it out.) They re-balance all four tires, and move the bent wheel to the rear, to reduce the shaking. This worked to an extent, and it reduced the overall shaking by ~50%. \n\nThis year, I decided to buy aftermarket wheels for the summer, so I could have a smooth ride again. Put the stock all-season tires on the new wheels, took it to the tire specialist to be mounted and balanced, and it still shakes. I have no idea at this point what it could be.\n\nThere's no drifting, and the shaking doesn't affect the steering wheel much, if at all, so I'm not sure it's an alignment issue. It's mostly felt in the seat.\n\nThe wheels were brand new. It's done it with different wheels and different tires.\n\nI don't feel any shaking during braking, so it's not the rotors. \n\nI'm at a bit of a loss, and need a little advice before I try something else.\n\nThank you.", "topk_rank": 4 }, { "id": "corpus-325131", "score": 0.6785366535186768, "text": "Combustion engines have a relatively narrow range of rotation rates where they can operate. When turning slowly, they are inefficient and [produce little torque, or cannot run at all](_URL_1_). That's because the force provided from a combustion event has to synchronize with the expansion of the cylinder volume, or the energy it represents ends up being wasted. If the cylinder is opening up too slowly, the fuel cannot fully combust. And each combustion event has to rotate the crank at least enough to enable the next one in the cycle. This is also why gas cars need a \"starter;\" the engine must already be turning in order for it to work. An electric motor, on the other hand, can produce torque at zero RPM, and while there is a \"torque curve\" it's [shallower and wider](_URL_0_) than that of a combustion engine. Most electric vehicles are actually geared down because the most efficient range for the motor is very much faster than typical wheel RPM but it's a single, fixed gearbox.", "topk_rank": 5 }, { "id": "corpus-320936", "score": 0.6785028576850891, "text": "Try this: Fill a glass with water and rotate the cup from rest. The water will initially remain \"at rest,\" but eventually begin spinning along with the cup due to viscosity. The same will occur with the air in the tires of your car. This question actually has a lot of deep meaning as it elicits Newton's bucket argument for absolute space, the Mock principle and Relativity.", "topk_rank": 6 }, { "id": "corpus-13865", "score": 0.6783673167228699, "text": "Because when you accelerate, turn, or brake, you're putting extra wear on the tires doing that work. Having more weight on the tire also wears them out faster. That's why the rear tires of front-engine, front-wheel drive cars wear out the slowest, and why the rear tires of rear-engine, rear-wheel drive tires wear out the fastest. Rear tires of FF cars do almost no work and have less weight on them. Front tires of MR and RR cars do almost no work unless you're braking or turning and have less weight on them.", "topk_rank": 7 }, { "id": "corpus-161929", "score": 0.6782457828521729, "text": "To add to what Ionizzatore said there is also a AWD. This is similar but not exactly 4wd. And ALL WHEEL DRIVE has the potential to propel any of the 4 tires and adjusts which tire/tires it uses when/if you loose traction. A 4WD will spin all 4 tires if the hubs are locked.", "topk_rank": 8 }, { "id": "corpus-54260", "score": 0.6781570315361023, "text": "It takes a fair bit of oompf to get them going. Some have starter motors, but if the wind is just a bit slower for that one than others, it may not kick in. Also, they can have brakes put on so they're not spinning during maintenance.", "topk_rank": 9 }, { "id": "corpus-289077", "score": 0.678013801574707, "text": "This would require motors to be installed at each tire to spin it and match the speed. This also needs to be more exact as a missmatched tire speed will cause problems upon landing and this will also create an unwanted gyroscopic event. Commercial airplane tires get replaced after about 10 landings. Having the tire spin and match speed will cause more complications.", "topk_rank": 10 }, { "id": "corpus-118203", "score": 0.6779017448425293, "text": "You didn't ask but anti-lock brakes try to prevent this by detecting when a wheel stops spinning when it shouldn't (other wheels still spinning, for example) and releasing the brakes very briefly and then re-applying them over and over until you release the brake pedal or the vehicle stops. In some cars you can hear this when you hammer the brakes as a very fast thumping. FYI: if you have ABS, in an emergency stop situation just push the pedal down as hard as possible and don't release until safety is achieved. Some Mercedes have a panic stop feature that will do this for you if you do stand on the brakes, I.e. Will hold the brakes on until stopped. Pumping the brakes is the non-assisted method of stopping without skidding. As you approach skid, slightly release pressure until skid averted, then press again, over and over until safety is achieved.", "topk_rank": 11 }, { "id": "corpus-286708", "score": 0.6777334809303284, "text": "There is a limit to how fast you may spin rotors because the edges are going faster than the center. As the edges speed up and approach/ exceed the sound barrier, the shock waves and turbulence cause nasty problems both mechanically and aerodynamically.", "topk_rank": 12 }, { "id": "corpus-107291", "score": 0.6776586174964905, "text": "If there is less air in the tires, there is a larger piece of the tire that is \"bend\" . Bending a tire costs a lot of energy. This means you need more fuel for the same amount of distance.", "topk_rank": 13 }, { "id": "corpus-107586", "score": 0.6775106191635132, "text": "As you're looking at the front of a vehicle you want as small of a surface area as possible facing the oncoming wind. So, you don't cover up the wheels because that would be unnecessary added surface area. But, as you move further back you want the air to slip off the side of the vehicle so you cover the wheels so that they don't catch any more air.", "topk_rank": 14 }, { "id": "corpus-1062127", "score": 0.6774006485939026, "text": "Do I need to run them in or something? They were already oiled and ive not got the nuts too tight. They just dont seem as fast as I expected or do they roll for that long when I spin them", "topk_rank": 15 }, { "id": "corpus-110730", "score": 0.6774002313613892, "text": "To finish the job you need to abruptly swing the loose end in toward the curb. This can only be done if the loose end (the one out in the street) is the end with steerable wheels.", "topk_rank": 16 }, { "id": "corpus-172085", "score": 0.6773197650909424, "text": "The wheels significantly reduce the friction of just shoving it along the ground and once you get the heavy object rolling inertia will help keep it moving.", "topk_rank": 17 }, { "id": "corpus-2676642", "score": 0.6772732138633728, "text": "I have a Strada MT Evo and didn‘t use it for quite a while. I just used it for the first time in ages again, and recognised that when i hold the car mid air and press throttle, that until about 30% throttle only the front left and right rear start to spin/take all the power. If i give more power, the other 2 wheels start to gain speed as well, just not as fast as the 2 „main“ wheels", "topk_rank": 18 }, { "id": "corpus-324515", "score": 0.677261471748352, "text": "It will depend on more factors than simply the diameter of the tire. A larger diameter will give more resistance to change in its [rotational inertia](_URL_0_) than a smaller tire. When you are out next, pay attention to the diameters of different vehicles wheels. Less powerful vehicles (like the Prius, Smart car, etc.) which are designed for efficiency over speed will have smaller wheels because the motor would struggle to move the wheel with 20\" diameter wheels on it. The larger diameter wheel may cover more distance in a single rotation than a smaller diameter wheel, but because of its moment of inertia it will take more energy to turn it a single revolution. Add to that the likelihood that a larger-diameter wheel (or simply a larger diameter tire) will most likely weigh more than a smaller one, the added weight will also have an effect on a vehicles mpg.", "topk_rank": 19 } ]

[ { "id": "corpus-325417", "score": 0.6783435940742493, "text": "Slight pressure against your retina from the intraocular fluid (leading to sensory input as light) caused by the muscles pulling the eye around." } ]

[ { "id": "corpus-143990", "score": 0.6443349719047546, "text": "It's a process called synkinesis - the muscles that control eye movement are wired to the same nerve control endings, so a single signal from the brain moves both simultaneously, though they are capable of some independent movement via separate muscles that control focal length. Sometimes these muscles get out of sync and cause things like lazy eye. Synkinesis can also happen to other muscle/nerve pairings, sometimes naturally and sometimes as the result of improper healing after injury. This is why some people can't move some fingers without others moving. Some people, like myself, even experience one hand moving involuntarily when another is moved intentionally. When I grasp an object like a spoon or toothbrush in my left hand, my right sometimes makes the same shape without me meaning for it to.", "topk_rank": 0 }, { "id": "corpus-2652356", "score": 0.644323468208313, "text": "I've been to several eye doctors and they all have different opinons on what causes my extreme night glare and glowing things. One dr said dry eye, one said it was because my dominant eye was worse than my other eye but not by a lot. My prescription is really low,I think -0.75 and -0.5. I am not trying to ask for a diagnosis, I am trying to determine what kind of dr I need to see. It's very hard to see at night with the glare and the glow.\n\nHere are illustrations: (This is one of those green road signs and the glow I see around it. Notice it doesn't occur in corners) I cannot flip it correctly for the life of me.\n\nThis is the headlight glare which I am sure is more common. Mine just seems to be excessively long, like 15 feet. Excuse my horrible drawing: I cannot get it to turn around. The curvy part is the front of the car and the two things that look like eyes are headlights. I drew orange instead of yellow so you could see: \n\nWho would I see? I've had a normal eye exam. I've thought of seeing a vision therapist but I can't afford therapy. It's really causing night driving problems and I'm starting to become convinced its in my head but I know it's not.\n\nI don't know how to make links I hope this is okay.", "topk_rank": 1 }, { "id": "corpus-90107", "score": 0.6442654132843018, "text": "The condition is called nystagmus. It has to do with alcohol diffusing into the membrane of your inner ear. This changes the specific gravity of the membrane that is perceived as motion by your brain, which tries to accommodate. It’s coupled with an eye twitch to one side as you sense things moving, try to track with your eyes, and they quickly reset. The same process happens in reverse as you’re sobering up, with all of this changin direction. Have fun tracking this through your inebriation! Maybe with a couple selfie vids in the mirror?", "topk_rank": 2 }, { "id": "corpus-2343040", "score": 0.6442644596099854, "text": "Ever since I remember, I have had visual snow. In fact, it was only recently that I found out this wasn't normal. It in no way inhibits my visions, I have and have always had perfect sight. When It gets dark, the \"static\" gets worse, and I have minor hallucinations, nothing major, just dark blobs moving around, but very faint. What could have caused this? And is it ok to smoke weed if I have this? I have been for around a year, and when I smoke during the day it helps, during the night it slightly worsens.", "topk_rank": 3 }, { "id": "corpus-1901914", "score": 0.6442482471466064, "text": "So I've been getting more LD's lately, in total I've had about 7. But every LD I've had has been quite unclear. Like only some small parts of the eyes can see, the rest is just distorted and unclear. I've been staying calm as well(I think), but the distortion is always there, and after about 5-10 seconds I wake up.\n\nIs this something that will go away with time and experience, and/or is there any way to avoid the distortion and actually gain some clarity and not wake up after 5-10 seconds?\n\n**TL;DR: Whenever I'm Lucid I can only see small parts of my sight, rest is unclear and flashing black and white. Need help! =)**", "topk_rank": 4 }, { "id": "corpus-23745", "score": 0.6442217826843262, "text": "The reason you fall asleep is because of a hormon that is released; melatonin. Melatonin production is regulated partly by light. The more light that \"hit your eyes\", the less of this hormone is released. Your eyelids are quite effective at blocking out the bright light that halts the production of this hormone, as well as protect your eyes and distribute lubrication for the retina. You can read more about it here: _URL_0_", "topk_rank": 5 }, { "id": "corpus-137550", "score": 0.6441988348960876, "text": "Are you trying not to blink? Cause you need to blink to keep your eyes from drying out.", "topk_rank": 6 }, { "id": "corpus-192495", "score": 0.6441935300827026, "text": "A lot of the data your brain uses to control balance is visual. Try walking a balance beam with your eyes closed. This phenomenon happens sometimes because your brain doesn't realize that the object it is using as a stationary frame of reference for your movement, is itself moving. Your brain really thinks you are moving backwards and can trigger the sensation. That's why this happens more if you are not paying attention to what you're looking at, and the car is a large portion of your field of vision. Without another object to tell your brain that the car is actually moving, for a split second it assumes you are rolling backwards.", "topk_rank": 7 }, { "id": "corpus-105805", "score": 0.6441890597343445, "text": "Because it is a vortex. A vortex is made when the medium is spinning around a center. That center is the eye.", "topk_rank": 8 }, { "id": "corpus-1191256", "score": 0.6441813707351685, "text": "First of all sorry for my english. \n\n\nSo, I started to wear glasses 3 days ago because i have astigmatism of 1.50 in both eyes, so everything was normal and i see a LOT better with them but sometimes i noticed a weird “reflection” if i see a light, like a lamp or something, i also noticed that if i am watching a movie or playing videogames and in the screen appears a big white letters with a black background, i see the reflections of those letters too, like if below the letters there was a lake and you could see the reflection but with less brightness. I noticed that if i move my head up and down the reflection moves too so if before the reflection was below the letters, i move my head up and now its above the letters. I did some research but i find NOTHING about this or something similar of what is happening to me, i ask some friends and just one of them told me that is normal but 5 more told me that this doesn’t happen to them. This isn’t something too bad but tonight i went to Walmart and while i was driving i saw this reflections EVERYWHERE in all the lights of cars and lamps and driving like that was very uncomfortable, is this normal or is a problem with the glasses?\n\nThanks for reading this large post!", "topk_rank": 9 }, { "id": "corpus-277929", "score": 0.6441793441772461, "text": "If your eyelid muscles were off, your eyelids would generally be droopy/mostly closed. We have muscles to open AND to close the eyes. If they're paralyzed, then the eyelid will do whatever friction+elasticity dictates. If someone does have a paralysis of their eyelid muscles, a patch is often applied to the eye to force the eyelid completely closed, so that the eye doesn't get dry and damaged by the inability to blink. Yes, we are using our 'opening' eyelid muscles constantly when we are awake. We are using our 'closing' eyelid muscles a little bit when we are asleep.", "topk_rank": 10 }, { "id": "corpus-67386", "score": 0.6441379189491272, "text": "Water causes additional refraction. Light travels further into the fabric and less of it bounces back to reach your eyes.", "topk_rank": 11 }, { "id": "corpus-103286", "score": 0.644108772277832, "text": "Because your eyes are still trying to focus on something. If you try to imagine the image of a lion let's say, you can do so while staring off into space because you're brain isn't focusing on what you're seeing. If you close your eyes the same is true. But, if you look into the dark and try to make the lion appear it's not going to work because that would be you hallucinating something using your vision.", "topk_rank": 12 }, { "id": "corpus-63538", "score": 0.6440931558609009, "text": "It's called positive after image. It is usually because the photoreceptors of your eye are still sending signals to the brain for a brief of a second. this persistence is because of the molecular mechanism of vision in which there is a change in the pigments present in these receptors that initiates electrical impulses!", "topk_rank": 13 }, { "id": "corpus-313273", "score": 0.6440830826759338, "text": "You're imagining this whole thing wrong. Imagine you're in a perfect vacuum and perfect darkness. If there's a laser shining directly into your eyes, you will see it, because the photons will enter your retina and activate your receptors. If the beam of light is completely missing your eyes, imagine a laser ray completely missing you, you will see nothing. If the same laser reflects of a surface and hits you in the eyes, you see it again. A laser is just a very thin stream of photons, and in normal conditions, you can sometimes see the beam because it's being scattered off dust in the air, but in clear conditions you don't see it unless it's reflected (and scattered too) off a surface, in which case you see a red dot. In a vacuum it becomes impossible to see any light unless it's hitting you directly in the retina, or is being reflected of something else.", "topk_rank": 14 }, { "id": "corpus-312234", "score": 0.6440746784210205, "text": "It's a purely physiological effect, or at least that's how my professor explained it to our class last week. More broadly, these types of full-body twitches are called [myoclonic jerks](_URL_0_), while the hypnagogic jerk refers specifically to a jerk that occurs while the subject is in hypnagogic reverie (descending Stage 1 sleep). Sometimes, the hypnagogic state terminates in a hypnagogic jerk, usually after the subject experiences some imagery of falling. According to my professor, we experience myoclonic jerks because different parts of the skeletal musculature relax at different rates. According to the prof, muscles relax before tendons can account for this relaxation, and you experience a spasm.", "topk_rank": 15 }, { "id": "corpus-161212", "score": 0.6439856290817261, "text": "Yup, instinct is the cause here. Lack of light makes it harder to see danger, and its not so much that there *is* something dangerous out there, its that something dangerous *could be* out there. Your body doesn't like taking risks on survival, so your instinct is to get to somewhere where you can see more clearly ASAP.", "topk_rank": 16 }, { "id": "corpus-156198", "score": 0.64397132396698, "text": "You're deforming your retina - which is the organ that receives the light from your eye's lense. This obviously causes a measurable distortion in your vision. The spot appears on the opposite side of where you poke because the light from that part of your vision is what hits the distorted part of your retina (I'm sorry this is a very poor explanation, but it's hard to describe the light with words - I'd really need a diagram to explain it properly).", "topk_rank": 17 }, { "id": "corpus-24272", "score": 0.6439592242240906, "text": "A portion of your brain spends all your waking hours \"scanning\" your vision for eyes looking at you. Think of it as a hard-wired defense mechanism that is a hold over from the earlier days of humans. If you're about to be attacked, your attacker is probably looking at you after all. **Edit** Honestly don't remember where I heard this for the first time. Maybe Radiolab? [Here's a really sound full description from Forbes via Quora.](_URL_2_) Author is a computational neuroscientist and software engineer, so in the immutable words of Reading Rainbow, you don't have to take my word for it...", "topk_rank": 18 }, { "id": "corpus-300888", "score": 0.6438402533531189, "text": "You have a [Vestibulo-ocular reflex](_URL_0_) which automatically corrects your gaze to accommodate any self-initiated head movement. To demonstrate this reflex, nod your head. Your eyes will automatically move counter to the direction of your head in order to keep these words fixed on your retina. Jaw movements during eating usually create some movement of the head, but the vestibulo-ocular reflex compensates for it by moving the eyes as well, so the world appears stable. Crunchy foods, however, may move or shift the jaw in unpredicted ways due to resistance of the hard material--the vestibulo-ocular reflex may not be able to compensate 100% for these unpredicted vibrations of the head, and so you get a slight \"jiggle\" on your retina. Arguably, as H1deki says, this effect is most noticeable with digital displays or other objects with crisp, high-contrast edges. Hope this helps :)", "topk_rank": 19 } ]

[ { "id": "corpus-325418", "score": 0.7591184973716736, "text": "_URL_0_ That episode of radiolab is very interesting and the first section talks directly of how dolphins sleep. TL;DL - Their brains are a bit more divided than ours (left/right) and they put one hemisphere to sleep at a time, while the other hemisphere functions enough to just keep them surfaced and breathing. They call it logging since they just kinda float there like logs. They then switch hemispheres. Its been a while since I listened to the podcast and I'm sure someone else can come along and give a better/more specific answer, but seeing as its been 4 hours without any responses, I thought I'd take a crack at it." } ]

[ { "id": "corpus-28585", "score": 0.7107158303260803, "text": "A few things: 1. we can sleep with one eye open, technically...just like we can sleep with both open. 2. We don't have the capacity to put a single hemisphere of our brain into \"sleep mode\". This is the wonderful capability of the dolphin and it's not so much their eye (although that part is true) it's their _brain_. Our brains can't do this - we're all or nothing in the sleep department.", "topk_rank": 0 }, { "id": "corpus-128596", "score": 0.7104010581970215, "text": "They have a different sleep pattern from other animals. They can sleep but they don't have eyelids, they will reduce metabolism and rest and recover the same way our bodies recover during sleep. It depends also on the species, for example a dolphin can rest one lobe of its brain at a time. Some fish like a Wrasse sleeps in tiny openings in rocks and puts a mucous coating around it and sleep that way. I've had a clown fish that sleeps dead still on top of a coral or basically anywhere it felt comfortable and safe, even in the filter one time on top of filter media (he was a baby at the time so managed to squeeze through). My other clownfish swim in a very peaceful motion while one of them likes to press his fins against the sides to keep him still. So they've got their habits of \"sleeping\" but their eyes do not close cause they don't have eyelids. Sharks have eye lids but are different.", "topk_rank": 1 }, { "id": "corpus-324928", "score": 0.6898751258850098, "text": "Yes, they do since they're mammals, but they seem to come out when it's time to nurse. Here's an [interesting article on whale nursing](_URL_0_) that I found for you. :)", "topk_rank": 2 }, { "id": "corpus-315373", "score": 0.6849040985107422, "text": "That's not something that's been researched to the point of having an answer. For almost all deep sea organisms, we don't even know their general operating behavior patterns, let alone their sleep cycles. Since they exist in an environment that we cannot access, we can only observe them by doing one of two things: remove them from their environment and place them in pressurized tanks at the surface, or descend to their level in submersibles or with deep ROVs. Both of those things constitute a major disruption of their regular environments. How the tank disrupts is pretty obvious, and the capture and removal process can be traumatic as well. And subs or ROVs make noise and have lights, both of which would cause the animal to be aware of it's presence and act accordingly. It's going to take a lot, lot longer and a lot more study for us to know anything like that.", "topk_rank": 3 }, { "id": "corpus-166612", "score": 0.6822738647460938, "text": "Dolphins do. Some Whales as well. If you watch the cove, the guy that trained the dolphins for Flipper tells a story of how a dolphin committed suicide in his arms by refusing to come up for air. _URL_0_", "topk_rank": 4 }, { "id": "corpus-314304", "score": 0.6821249723434448, "text": "Mammals and birds have REM sleep, and other stages of sleep that humans also experience. We just can't ask them about their objective experience of REM sleep or ask what they dream because, well, we can't really talk Cat or Parrot or Dolphin.", "topk_rank": 5 }, { "id": "corpus-250746", "score": 0.6809903383255005, "text": "Generally speaking, cetaceans (whales, dolphins, and porpoises) have a 'melon', and oily fatty organ between the tip of their rostrum (nose) and their blowhole. Vibrations (sound) are made in the blowhole passages which is amplified by the melon and directed outwards. By contracting or relaxing their melon they can produce different sounds. Google belugas, they have a crazy developed melon and can make hundreds of different sounds. You can actually see their melon move when they produce noises. They (along with walruses) are called the canaries of the sea for that reason.", "topk_rank": 6 }, { "id": "corpus-171022", "score": 0.6788803339004517, "text": "Whales are mammals, they need to breath air. They are not fish, so they can't extract oxygen from water and stay down forever. Instead they breach to breathe and just hold their breath a long time.", "topk_rank": 7 }, { "id": "corpus-99568", "score": 0.6754290461540222, "text": "Not all fish are known to sleep. Those fish that appear to sleep, do so with their eyes open. There are nocturnal fish, and also fish that live in environments that are perpetually dark.", "topk_rank": 8 }, { "id": "corpus-459", "score": 0.6748257279396057, "text": "They get it from the food that they eat. Whales, and dolphins, can't starve to death, they die of dehydration first. They do get a little bit from sea water but their kidneys can't remove much salt so if they accidentally drink too much sea water when they eat that could kill them.", "topk_rank": 9 }, { "id": "corpus-267217", "score": 0.6732600927352905, "text": "There are animals that sleep on the surface of water. Otters [sleep floating on their bellies](_URL_1_), and seals can [sleep with just their heads above water](_URL_2_). Sometimes ducks will sleep floating [(PDF source)](_URL_0_). There is also at least one animal that spends most of its life floating: the [Portuguese man o' war](_URL_3_). This jellyfish-like animal has a air-filled sack that keeps it floating at the ocean's surface while its tentacles hang into the ocean below. Strangely this \"creature\" is actually a colony of individuals living together with specialized body types. There may be other ocean floaters, but this is the first that came to mind.", "topk_rank": 10 }, { "id": "corpus-292318", "score": 0.6688266396522522, "text": "We really have no idea since no one was there to see, but what we can do is observe modern long neck animals and try to come to a conclusion on how they may have done it. Giraffes sleep by curling their necks and using their own bodies as pillows. Like this _URL_0_ Ostriches do it differently. They keep their heads upright and look like they are wide awake but are actually fully asleep. _URL_1_ Since birds are descended from dinosaurs we might say this is a more appropriate analogue but there is the possibility they slept like giraffes or in some other way.", "topk_rank": 11 }, { "id": "corpus-1981035", "score": 0.668487012386322, "text": "Don't other mammals like owls and dolphins sleep with one of their eyes open to subconsciously watch for predators? Why don't us humans do so?", "topk_rank": 12 }, { "id": "corpus-800892", "score": 0.6662904024124146, "text": "People aren't usually fully asleep when they sleep walk they are usually just half asleep and I wondered if that's what it's like for animals all the time although some more intelligent animals like dog/wolves, dolphins, and many primates might be a step up from this.", "topk_rank": 13 }, { "id": "corpus-278359", "score": 0.6652460098266602, "text": "Whales get the water they need from their food. The way they digest food extracts water from their prey which keeps them hydrated. Dolphins actually get their water the same way. The funny thing is a dolphin will actually drink water if you sprayed fresh water in their mouths. The issue is they can't distinguish thirst from hunger so they will actually not eat if they are given water.", "topk_rank": 14 }, { "id": "corpus-260546", "score": 0.6652235388755798, "text": "There is a tolerance system involved. Whales don't dive from land to water so their receptor have time to adjust when they enter cold water(they enter gradually). For seals, bears and other \"furry\" mammals there is an extra thin layer of air/water that gets trapped in the fur and acts as an insulating layer. Even if they jump into cold water the receptors \"get used\" to the temperature and their signals get blocked after a while and only get reactivated when their signal changes(water temperature changes).", "topk_rank": 15 }, { "id": "corpus-142436", "score": 0.6625633835792542, "text": "Whats even more mind boggling is how Hippos sleep...they can actually sleep underwater, and they surface to breathe automatically, while still asleep.", "topk_rank": 16 }, { "id": "corpus-59521", "score": 0.6625054478645325, "text": "[S2E1: Sleep](_URL_4_) This hour of Radiolab: birds do it, bees do it...yet science still can't answer the basic question: why do we sleep? Every creature on the planet sleeps--from giant humpback whales to teeny fruit flies. What does it do for us, and what happens when we go without? We take a peek at iguanas sleeping with one eye open, get in bed with a pair of sleep-deprived new parents, and eavesdrop on the uneasy dreams of rats.", "topk_rank": 17 }, { "id": "corpus-251328", "score": 0.6622129082679749, "text": "Dolphins fall under toothed whales, called odontocetes. One of the differences between toothed whales and baleen whales is their number of blow holes. Toothed whales have 1 blow hole while baleen whales have 2. The \"missing\" blow hole is a highly specialized structure called the monkey lips, also called phonic lips. These vibrate to produce high frequency sounds like those used for echolocation. This sound is amplified and focused by the melon, an oily tissue above the rostrum (beak), which functions as an acoustic lens. Vocal cords in dolphins are not known to have a function. They can make noises with their mouth, but it's from snapping their jaws shut.", "topk_rank": 18 }, { "id": "corpus-184687", "score": 0.6621624231338501, "text": "If their skin isn’t kept wet, it causes severe damage to their body. That’s why in rescue videos you see people using hoses, towels, everything they can to keep them soaked with water. Another issue with whales/dolphins is their body weight on land. They’re meant to be in water — so having all that weight on land puts enormous pressure on their organs.", "topk_rank": 19 } ]

[ { "id": "corpus-325419", "score": 0.7185235023498535, "text": "* _URL_1_ * _URL_2_ * _URL_3_ * _URL_0_ tl;dr most whales have the ability to sleep with one half of their brain at a time." } ]

[ { "id": "corpus-284379", "score": 0.6819928884506226, "text": "[Yes, cetaceans can do unihemispheric slow wave sleep.](_URL_0_)", "topk_rank": 0 }, { "id": "corpus-318440", "score": 0.6812174320220947, "text": "Many fish and whales will sleep with only one half of their brain, such that the other half can remain alert for danger (for [dolphins] (_URL_0_): left side of brain sleeps so they will swim in a circle with their left eye on the outside, watching for predators)", "topk_rank": 1 }, { "id": "corpus-113264", "score": 0.6783701777458191, "text": "Fish do sleep. Fish sleep in a few different ways. Some fish sleep with half their brain at a time so that the other half is alert enough to keep them away from predators. Parrotfish [build a cocoon of mucus](_URL_0_) to sleep in that protects them from predators. They sleep so soundly in their cocoons that divers have been known to play catch with them without the fish waking up. But yes, fish totally sleep.", "topk_rank": 2 }, { "id": "corpus-297764", "score": 0.676167368888855, "text": "To add to what /u/hiearthpeople said, cetaceans sleep in a pod with one eye open. They all swim in a circle, and the eye that is facing the outside of the circle corresponds to the opposite side of their brain. That means they swim clockwise and counterclockwise depending on what hemisphere of the brain they are resting. Granted, I’d imagine that their sleep cycles aren’t as deep as a humans. They can do this, because their hemispheres are more separated than a humans. EDIT: I had it backwards regarding how separated their hemispheres were so I’ve corrected it", "topk_rank": 3 }, { "id": "corpus-186186", "score": 0.6706912517547607, "text": "It appears that scientists do know where blue whales mate. According to a source I located, they made near the equator. During their mating ritual, they dive into the ocean, and return quickly to the surface, followed by intercourse. Source: [_URL_1_](_URL_0_)", "topk_rank": 4 }, { "id": "corpus-325418", "score": 0.6705021858215332, "text": "_URL_0_ That episode of radiolab is very interesting and the first section talks directly of how dolphins sleep. TL;DL - Their brains are a bit more divided than ours (left/right) and they put one hemisphere to sleep at a time, while the other hemisphere functions enough to just keep them surfaced and breathing. They call it logging since they just kinda float there like logs. They then switch hemispheres. Its been a while since I listened to the podcast and I'm sure someone else can come along and give a better/more specific answer, but seeing as its been 4 hours without any responses, I thought I'd take a crack at it.", "topk_rank": 5 }, { "id": "corpus-284380", "score": 0.6680716276168823, "text": "This behavior is called unihemispheric sleep, where the separate halves of the brain alternate between being awake and being asleep. However, just like with humans, dolphins (and other animals with this behavior) only need to sleep in this state for 8 hours per day. Researchers think this behavior evolved so that dolphins could surface to breathe, even when sleeping. There was actually a recent study performed by researchers in San Diego showing that even during a unihemispheric sleep state, dolphins had remarkable accuracy when using echolocation to oversee their environment and detect prey. Source: _URL_4_", "topk_rank": 6 }, { "id": "corpus-315373", "score": 0.6651546955108643, "text": "That's not something that's been researched to the point of having an answer. For almost all deep sea organisms, we don't even know their general operating behavior patterns, let alone their sleep cycles. Since they exist in an environment that we cannot access, we can only observe them by doing one of two things: remove them from their environment and place them in pressurized tanks at the surface, or descend to their level in submersibles or with deep ROVs. Both of those things constitute a major disruption of their regular environments. How the tank disrupts is pretty obvious, and the capture and removal process can be traumatic as well. And subs or ROVs make noise and have lights, both of which would cause the animal to be aware of it's presence and act accordingly. It's going to take a lot, lot longer and a lot more study for us to know anything like that.", "topk_rank": 7 }, { "id": "corpus-7107", "score": 0.6647332310676575, "text": "Birds and other animals for that matter don't sleep exactly the same as humans do. Birds for example sleep sitting all the time. A human sitting on a branch would fall down the second he started sleeping. Most animals sleep standing on all fours. Dolphins sleep while swimming. And migratory birds sleep while flying. Or sailing in most cases. Their brains do not shut down all the way so parts of it sleep while the rest is awake.", "topk_rank": 8 }, { "id": "corpus-171022", "score": 0.6584440469741821, "text": "Whales are mammals, they need to breath air. They are not fish, so they can't extract oxygen from water and stay down forever. Instead they breach to breathe and just hold their breath a long time.", "topk_rank": 9 }, { "id": "corpus-128596", "score": 0.6561362743377686, "text": "They have a different sleep pattern from other animals. They can sleep but they don't have eyelids, they will reduce metabolism and rest and recover the same way our bodies recover during sleep. It depends also on the species, for example a dolphin can rest one lobe of its brain at a time. Some fish like a Wrasse sleeps in tiny openings in rocks and puts a mucous coating around it and sleep that way. I've had a clown fish that sleeps dead still on top of a coral or basically anywhere it felt comfortable and safe, even in the filter one time on top of filter media (he was a baby at the time so managed to squeeze through). My other clownfish swim in a very peaceful motion while one of them likes to press his fins against the sides to keep him still. So they've got their habits of \"sleeping\" but their eyes do not close cause they don't have eyelids. Sharks have eye lids but are different.", "topk_rank": 10 }, { "id": "corpus-59521", "score": 0.6546018719673157, "text": "[S2E1: Sleep](_URL_4_) This hour of Radiolab: birds do it, bees do it...yet science still can't answer the basic question: why do we sleep? Every creature on the planet sleeps--from giant humpback whales to teeny fruit flies. What does it do for us, and what happens when we go without? We take a peek at iguanas sleeping with one eye open, get in bed with a pair of sleep-deprived new parents, and eavesdrop on the uneasy dreams of rats.", "topk_rank": 11 }, { "id": "corpus-324928", "score": 0.6531208157539368, "text": "Yes, they do since they're mammals, but they seem to come out when it's time to nurse. Here's an [interesting article on whale nursing](_URL_0_) that I found for you. :)", "topk_rank": 12 }, { "id": "corpus-32618", "score": 0.6501633524894714, "text": "I read about this recently. I believe dolphins can sleep with half their brain at one time (I'll delete my answer if someone who knows posts) so essentially they both get the benefit of sleep while they're partially awake.", "topk_rank": 13 }, { "id": "corpus-117594", "score": 0.6487574577331543, "text": "There are two main reasons: First, whales are massive but buoyant. In the ocean, water pushes on all sides and helps to support their bodyweight. On land without the buoyancy from the water, the whales struggle to lift the weight of their own bodies to take a breath. It's like when you lift a heavy weight underwater easily but then can't lift the same weight out of the water. Second, whales are surrounded by thick blubber to insulate them from the cold water. On land, there's no water to pull away their body heat and they are more exposed to the sun. They become very susceptible to overheating unless cooled down by water.", "topk_rank": 14 }, { "id": "corpus-267217", "score": 0.644126832485199, "text": "There are animals that sleep on the surface of water. Otters [sleep floating on their bellies](_URL_1_), and seals can [sleep with just their heads above water](_URL_2_). Sometimes ducks will sleep floating [(PDF source)](_URL_0_). There is also at least one animal that spends most of its life floating: the [Portuguese man o' war](_URL_3_). This jellyfish-like animal has a air-filled sack that keeps it floating at the ocean's surface while its tentacles hang into the ocean below. Strangely this \"creature\" is actually a colony of individuals living together with specialized body types. There may be other ocean floaters, but this is the first that came to mind.", "topk_rank": 15 }, { "id": "corpus-79443", "score": 0.6434942483901978, "text": "Yes, they sleep half of their brain at a time, so that they can still float/swim/breathe while sleeping. The other half of their brain is able to keep an eye out for danger as well.", "topk_rank": 16 }, { "id": "corpus-288401", "score": 0.6424967050552368, "text": "Belugas have extra blubber to stay warm in the Arctic Ocean. Good question though. Most of the baleen whales are pretty streamlined until they open their mouth to eat. Sperm whales have that huge, spermaceti-carrying head. That's probably more important to them than being super streamlined though, because it enables them to sound to great depth with less swimming effort. They let cold water circulate in there when diving, which cools off the spermaceti and makes it harden into a wax. This phase change increases the density of the spermaceti which creates a [downforce of about 860 lbs](_URL_0_).", "topk_rank": 17 }, { "id": "corpus-99568", "score": 0.6422096490859985, "text": "Not all fish are known to sleep. Those fish that appear to sleep, do so with their eyes open. There are nocturnal fish, and also fish that live in environments that are perpetually dark.", "topk_rank": 18 }, { "id": "corpus-321279", "score": 0.6391122341156006, "text": "Whales are placental mammals so they nurse their young by definition. Their nipples are located under special slits in their abdomen that are normally inverted--this keeps the hydrodynamic. When they calf wants milk he or she will prod his or her mother's belly with their snout and the mother whale can open the slit and reverse her nipples to the point out. Whale calves cannot suckle like most other mammals since their mouths don't work that way and they cannot create suction, so they have specially shaped tongues that they curl around the nipple and then the mother kind of just sprays the milk in their mouth through the tongue. Their milk is ~15x fattier than whole cow's milk so it comes out like yogurt. Hopefully you don't have a vivid imagination.", "topk_rank": 19 } ]

[ { "id": "corpus-325420", "score": 0.7657762765884399, "text": "Bleach (sodium hypochlorite) kills pretty much everything. I work in a BioMed lab, and we use bleach as a standard disinfecting agent before we dispose of biological waste. Bleach is not an antibiotic like many agents used. Instead, it denatures the proteins that comprise microbes, usually irreversibly. Also, the high basicity of bleach can cause damage to cells. Bleach or ethanol (EtOH) are industry standard means of disinfecting in the lab setting. Bleach is used primarily for killing microbes in a sample or beaker (say I have a flask of bacteria that needs to be disposed of), EtOH is used to disinfect surfaces and equipment (spray down the micro-pipettes, biosafety cabinet surface, your hands, etc). Bacterial adaptations are usually the result of antibiotics. Neither bleach nor EtOH are antibiotics, so the chance of adaptations is very, very low. I've never heard of it happening." } ]

[ { "id": "corpus-60172", "score": 0.727330207824707, "text": "[This article](_URL_0_) provides good information on this, but the long and short of it is that the chemical structure of bleach makes it so that it cannot penetrate the membrane and actually kill the mold, whereas acetic acid (vinegar) can.", "topk_rank": 0 }, { "id": "corpus-2411049", "score": 0.7244079113006592, "text": "When properly diluted it kills virus with ease and a gallon goes a very long way. If the situation deteriorates you are sitting on a supply that is useful for water purification or even setting up an impromptu medical theater. Bleach has a relatively short shelf life of 8 months but you can also make your own using calcium hypochlorite which lasts many years. A small amount of calcium hypochlorite can be used to make thousands of gallons of bleach and millions of gallons of safe water but requires extra care because it is a dangerous lab chemical. I got mine from Amazon.\n\nDisinfecting solution and sanitizing solution are the same mixture of bleach and water but different strengths. Sanitizing solution is ubiquitous in the food and beverage industry because it cheap, easy to use, and extremely effective. A chef that trained me said 'bleach is the enemy of all life,' yet it is perfectly safe for humans when used correctly. Normally sanitizing-strength solution is best for household use but because we are dealing with a known or suspected pathogen we will use only disinfectant-strength solution.\n\nDisinfecting solution remains effective for 24 hours so we replace the \\`sanitizer-bucket\\` each morning, often re-using the same container and cloth for several days. It sits on the kitchen counter with a dish-cloth floating in it. Use the wrung-out, damp cloth on commonly touched things like phones, keys, buttons, knobs and remotes but also on food contact surface. Afterwards just put the cloth back in the sanitizer-bucket for next use. \n\nThis is a pandemic-specific measure but is excellent protection against a whole host of other potentially life-threatening medical problems like food-borne illness and bacterial or fungal infections. \n\n&amp;#x200B;\n\n**Disinfectant solution:**\n\n**2 tablespoons bleach to 1 quart water**", "topk_rank": 1 }, { "id": "corpus-1253441", "score": 0.723570704460144, "text": "My bottle of bleach claims to kill 99.9% of all household germs. What is the .1% of germs that are not killed with bleach?", "topk_rank": 2 }, { "id": "corpus-1253317", "score": 0.7188431620597839, "text": "I own a vacation rental and the health and safety of my guests and family is very important to me. I understand a 10% solution of bleach will effectively disinfect hard surfaces but what about soft surfaces? Specifically upholstery and carpeting.", "topk_rank": 3 }, { "id": "corpus-187915", "score": 0.7164983749389648, "text": "bleach is a highly reactive oxidation chemical that basically destroys the molecules responsible for coloring as far as I know", "topk_rank": 4 }, { "id": "corpus-80175", "score": 0.7163758873939514, "text": "It's thought that bleach and most disinfectants are harsh chemicals that attack living things generally and it's not possible for the bacteria to evolve resistance. That's backed up by the fact that despite widespread use of bleach for decades, bacteria have not evolved to resist it. If an antibiotic is a special forces assassin out to kill the bad guy without harming the civilians, then bleach is carpet bombing the city until nothing is left. That general action is why we can't base medicines on bleach - it kills our own cells just the same as the bacteria. That said, some cleaning products *do* use chemicals that behave more like antibiotics and there is a rising opposition to them. Last September the USA prohibited hand cleaners from being marketed as 'antibacterial'.", "topk_rank": 5 }, { "id": "corpus-30131", "score": 0.7156695127487183, "text": "Bleach destroys protein, the fundamental building block of all life. Bacteria can't get along without being made of protein -- it's what they are. They could evolve a protective coating, but bleach occurs *very rarely* in nature, and such a coating would get in the way of everything else the bacteria needed to do.", "topk_rank": 6 }, { "id": "corpus-99275", "score": 0.7132255434989929, "text": "Bleach will burn the crap out of your mouth, throat, esophagus, stomach lining, etc. It will possibly make you vomit and get diarrhea as well. If it's undiluted it will kill you by basically dissolving all the tissue it comes into contact with.", "topk_rank": 7 }, { "id": "corpus-90475", "score": 0.7130385637283325, "text": "No, developing bleach resistance is nigh impossible because that would literally require the microbe to develop a coat of metal, bleach can pretty much burn through anything organic. Also, the problem with antibiotic resistant bacteria is not that they are completely impervious to antibiotics (simply up the dose and they will still die), it's just that they evolve to be impervious enough so that we can't use the antibiotic on people anymore, as the dosage needed to kill the resistant bacteria will kill the human too. This is not a problem with bleach, considering no one will be drinking it to treat strep throat. So even if somehow bleach resistance starts developing, no problem, just pour on more bleach.", "topk_rank": 8 }, { "id": "corpus-173379", "score": 0.7113108038902283, "text": "Because bleach doesn't *medically poison* them, it *physically destroys* them. It would be like me and you growing resistance to shotguns.", "topk_rank": 9 }, { "id": "corpus-71167", "score": 0.7109302282333374, "text": "Soap and water is all you need; it removes the bacteria. One caveat is an old wood cutting board with indentations from previous knife cuts. Bacteria can get trapped in there. If you don't have a smooth surface, clean with a stiff brush to reach those crevices. BTW, bleach fumes are neurotoxic.", "topk_rank": 10 }, { "id": "corpus-2598447", "score": 0.7100356221199036, "text": "There’s a lot of memes about drinking bleach to die but what does it actually do to your body?", "topk_rank": 11 }, { "id": "corpus-100101", "score": 0.7091737389564514, "text": "Not the answer you're looking for, but: color-safe bleach is peroxide-based, not chlorine-based, and is absolutely ideal for getting blood stains out of anything. (I'm an anesthesiologist; getting blood on your clothes is part of the job.)", "topk_rank": 12 }, { "id": "corpus-254054", "score": 0.7070125341415405, "text": "At least for bleach, Clorox has this [to say](_URL_0_): > Household bleach begins and ends as salt water in a fully sustainable cycle. There's a significant difference between \"bleaching\"-- the name often associated with the manufacturing of paper products -- and household bleach. > During consumer use and disposal, about 95 percent to 98 percent of household bleach quickly breaks down. The remaining two percent to five percent is effectively treated by sewer or septic systems. > Bleach does not contaminate ground water because it does not survive sewage treatment - either in municipal sewage treatment plants or in septic systems. Thus, there are no harmful effects of bleach in the environment. Wikipedia provides a more objective source, summarizing: > A Risk Assessment Report (RAR) conducted by the European Union on sodium hypochlorite conducted under Regulation EEC 793/93 concluded that this substance is safe for the environment in all its current, normal uses", "topk_rank": 13 }, { "id": "corpus-60546", "score": 0.7067251205444336, "text": "Bleach oxidizes stuff. Oxidation is a chemical reaction. When you change the chemical makeup of cells, you generally kill them. Therefore, large concentrations of bleach will cause lots of chemical changes and cells can't recover, so everything dies.", "topk_rank": 14 }, { "id": "corpus-309656", "score": 0.706506073474884, "text": "My guess is those figures leave some bacteria surviving as a \"cover your ass\" sort of thing from a liability perspective. From what we know, 10% bleach, for example, will kill everything, yet bleach-containing products still have that 99.9% figure. Assuming that figure is scientific and real, bacteria can form biofilms that can prevent activity of certain toxic agents, like antimicrobials and antibiotics, due to poor diffusion/local concentrations of the toxic agent. Also, if the surface one is cleaning on is porous, the cleaner may not hit every nook and some bacteria may survive. The cleaners themselves could probably kill most everything in isolation on a flat dish, for example, with proper mechanical scrubbing, it's just a matter of adequate exposure, which is why I think it isn't 100%. Edit: also I forgot that some bacteria can sporulate. Bacteria that are in spores can survive pretty extreme environments, like vacuum, desiccation, and extreme temperatures.", "topk_rank": 15 }, { "id": "corpus-644733", "score": 0.7061320543289185, "text": "My roommate uses household bleach to clean everything (clothes, shoes, floors, table tops, appliances ect.) I've explained to him that it is kind of dangerous to use such a harsh cleaning agent so often, but he insists. He cleaned the water dispenser with bleach and I am worried about it getting into the drinking water. Am I overthinking this or could this damage the body over time?", "topk_rank": 16 }, { "id": "corpus-240120", "score": 0.7057727575302124, "text": "chlorine bleach will react with and oxidize almost everything that it touches. also, another very important source of contamination that can make you very sick are endotoxins, which are sugar molecules sticking out of bacteria. these are not destroyed by normal sterilization procedures (eg autoclaving). the bacteria might die, but those molecules remain and elicit a (sometimes severe) immune response. _URL_0_", "topk_rank": 17 }, { "id": "corpus-108885", "score": 0.7052379846572876, "text": "Because alcohol kills everything. It's not possible for a microorganism to be resistant to alcohol. Alcohol is a tiny molecule that competes with water. Consequently, it's a dehydrating agent. Nothing can survive being catastrophically dehydrated. Same thing with bleach, albeit by a different mechanism. Bleach kills *everything.* You can't be resistant to bleach.", "topk_rank": 18 }, { "id": "corpus-278295", "score": 0.7049667835235596, "text": "This can be a big deal--there are often specific guidelines on how to clean for certain diseases and equipment. C diff infections are notoriously hard to kill, and require crazy amounts of cleaning in a patient's room to make sure it doesn't spread. Overall, it depends on quite a few things, including: * The toxicity of the disinfectant (putting bleach on a cut is not a great idea) * The type of pathogen you're concerned about--things like bacterial spores are very hard to kill, whereas larger viruses and \"normal\" bacteria are relatively easier. * Cost and ease of use For example, according to the CDC guidelines, alcohol solutions are okay to use to disinfect small surfaces like medication vials and external medical equipment like stethoscopes, but they are not effective enough to clean surgical materials. If you're curious, you can read the CDC guidelines [here](_URL_0_) (warning...not a thrilling read)", "topk_rank": 19 } ]

[ { "id": "corpus-325421", "score": 0.6409386992454529, "text": "According to [This paper] (_URL_0_) There has been detection of dust from outside of the solar system, possibly coming from several parsecs away." } ]

[ { "id": "corpus-317811", "score": 0.6088864803314209, "text": "The short answer is no. The typical impact velocity in the asteroid belt today is ~10 km/s, which results in destructive collisions. However planets form (and there's some uncertainty in this, to say the least) the impact velocities between bodies are low, allowing them to stick. The longer answer is - there's very little mass in the asteroid belt anyhow. Ceres has ~1/3 of the total mass, and has a total mass ~0.015% that of the Earth. Even if all the mass in the asteroid belt assembled into a single body, it would only be ~1% the mass of the moon.", "topk_rank": 0 }, { "id": "corpus-318783", "score": 0.6088849306106567, "text": "Typically all objects in a system will rotate the same direction, having formed from a cloud with some initial angular momentum. Major impacts late in formation and tidal forces can change the spin of a body and the axis about which it rotates, so you will see some planets and moons with retrograde or severely tilted rotation.", "topk_rank": 1 }, { "id": "corpus-135149", "score": 0.6088510155677795, "text": "Essentially, we don’t know for certain. It is _believed_ that they have solid cores, but that is (albeit well-evidenced) conjecture. One theory suggested that Jupiter has a diamond core. The sheer mass of these planets suggests that the core _should_ be solid, but at the moment we don’t know for sure.", "topk_rank": 2 }, { "id": "corpus-1774928", "score": 0.6088429093360901, "text": "idk how to really explain this but a GIANT meteor spawned in the city while i was playing online, can someone please explain what happened? maybe its an easter egg or something?\n\nPicture: ", "topk_rank": 3 }, { "id": "corpus-162811", "score": 0.6088410019874573, "text": "As far as we know, there's no reason *why* gravity does what it does. It's one of the fundamental interactions; it's just part of how the universe works. You get different gravities on different planets because gravity is created by mass. More massive planets create more gravity.", "topk_rank": 4 }, { "id": "corpus-249773", "score": 0.608833909034729, "text": "It's approximately three trillion kg and is about 4 km across. If you treat it like a sphere (which it isn't), it has about five millionths of Earth's gravity and an escape velocity of about 45 cm/s. These are very rough estimates.", "topk_rank": 5 }, { "id": "corpus-279377", "score": 0.608832061290741, "text": "Yes, geology and plate tectonics have a lot to say about this. By studying rocks, their layers, elemental and chemical composition and a bunch of other things, geologists can produce a surprisingly rich and detailed history of any rocky area. The caveat is the reconstructed history gets less accurate and there's less daa the further back you go. It basically depends on the rock from that era being still present near the surface in some form - not having being recycled into the mantle for example. Even so, because continental plates typically \"float\" they stick around a lot longer than oceanic plates which only last a couple of hundred million years. The oldest plates, known as cratons are billions of years old. This shows the known super-continents, but the older ones don't quite the fit definition of \"super\" and are more like continents: _URL_1_ _URL_0_ _URL_2_", "topk_rank": 6 }, { "id": "corpus-310094", "score": 0.6087818145751953, "text": "Elements up to lithium were created in the big bang, up to iron are created in stars, and up to uranium are created in supernovae. Elements bigger than uranium are generally created at atom smashers on Earth.", "topk_rank": 7 }, { "id": "corpus-181800", "score": 0.6087700724601746, "text": "1. There are heavy radioactive isotopes that sink to the earth’s core and generate heat 2. Crust and mantle material sinking into the core creates friction and heat. 3. Finally the original heat from when the earth formed from compressing dust has not dissipated, molten rock is a surprisingly bad conductor of heat.", "topk_rank": 8 }, { "id": "corpus-205484", "score": 0.6087683439254761, "text": "Follow up question: did pre-gun powder peoples ever try to replicate natural \"explosions\" like volcanic eruption, meteor impact (if they saw an actual impact) or perhaps even lightning strikes? Did these natural occurrences have any bearing on the invention of black powder?", "topk_rank": 9 }, { "id": "corpus-287385", "score": 0.608765721321106, "text": "That's a velocity (~20 km/s) that's within the velocity dispersion of stars in the Galaxy, and it's actually slower than the Earth's speed as it goes around the Sun (gravity assists further out increased it's speed to escape velocity where escape velocity was lower than it is near Earth). Any star-faring species has the capability of going that quickly, by definition. Something at rest relative to the Sun might have a similarly high velocity relative to their home star. That said, the odds of actually being picked up by an intelligent species are vanishingly small. It's a symbolic gesture, more in the spirit of \"Hey, you never know...\", instead of something intended to actually have a good chance of making contact. After all, now the end of the world wouldn't erase all record of humanity. There's still a bit of us, our art, our music, our ideas out there, even if the Earth itself is destroyed. Even if no one ever sees it, that's pretty cool, right?", "topk_rank": 10 }, { "id": "corpus-317683", "score": 0.6087603569030762, "text": "The energy required to create heavier elements comes from supernova of large stars. When they blow, they generate enough energy to fuse heavier elements. Since super large stars are the only ones who can create them under such specific circumstances, elements heavier than iron are relatively rare.", "topk_rank": 11 }, { "id": "corpus-324653", "score": 0.6086993217468262, "text": "[Here](_URL_1_) is the International Astronomical Union's definition for bodies in the solar system. Perhaps a similar definition could be applied to other bodies not in our solar system, using the galactic plane as a reference (potential problem: I'm not sure if we have accurate measurements of the invariable plane of the galaxy though, so I'm not sure if this could be done)? I really don't know. I haven't been able to figure out how or if it's done for bodies outside of our solar system, so here's how I would imagine doing it: Perhaps you could simply define the geographic north pole of a whole star system to be that around which the orbit of the planets is seen to be counter-clockwise (like it is in our solar system), when viewed from \"above\". Then you could simply reapply the IAU's definitions to that star system to identify north and south poles of planetary and smaller bodies.", "topk_rank": 12 }, { "id": "corpus-309017", "score": 0.6086727976799011, "text": "\"Earth will end up in the sun, vaporizing and blending its material with that of the sun,\" said Iowa State University's Lee Anne Willson. \"That part of the sun then blows away into space, so one might say Earth is cremated and the ashes are scattered into interstellar space.\" _URL_0_", "topk_rank": 13 }, { "id": "corpus-307001", "score": 0.6086642146110535, "text": "It varies geographically, but generally it is a mixture of sand (quartz) other minerals, fibers, plastics, human skin cells and other organics and the products of whatever organisms eat that organic material such as dust mites or microorganisms. This is certainly different from dust you'd find in the desert though.", "topk_rank": 14 }, { "id": "corpus-124605", "score": 0.6086596846580505, "text": "It's basically random. Continents and islands aren't really things though. Like look at the Moon or Mars, they have low valleys and canyons and high plateaus and mountains and stuff, but if Mars or the Moon had a shit ton of water on the surface, you would see continents and a scattering of islands, surrounded by ocean. The Earth is the same. Water has submerged most of the surface, but some areas are at a high enough elevation that they are above the ocean's surface, and these areas are continents and islands. Think of it this way, an island is just an isolated mountain that is mostly submerged under water. The islands of Hawaii are a mountain range, but most of it is underwater, with just the \"peaks\" above the surface.", "topk_rank": 15 }, { "id": "corpus-287295", "score": 0.6086304783821106, "text": "On earth, the phenomenon depends on two things: earth’s magnetic field, and earths atmosphere. I’m on my phone, so can’t write the entire process, but basically charged particles are shot out of the sun and then are captured by earth’s magnetic field and funnelled down into the atmosphere at the poles. The visible light that we see is the interaction between said charged particles and the stuffs in the atmosphere. So, to answer your question, it is very likely for many (dare I say most?) planets to have similar phenomena, so long as they have similar conditions (magnetic field and atmosphere).", "topk_rank": 16 }, { "id": "corpus-325128", "score": 0.6086289286613464, "text": "Those are in the milky way. When a supernova goes off in a distant galaxy, it looks like a new star has lit up: _URL_0_", "topk_rank": 17 }, { "id": "corpus-94936", "score": 0.6085919737815857, "text": "They haven't. Any images you've seen that represent our galaxy or solar system are artists's interpretations, and not actual images.", "topk_rank": 18 }, { "id": "corpus-319480", "score": 0.6085914969444275, "text": "They would have turned into a planet if it weren't for Jupiter's gravity and most of the remaining (a lot was lost from the solar system) mass is within a few big uns anyways. Read the wiki article _URL_0_", "topk_rank": 19 } ]

[ { "id": "corpus-325422", "score": 0.850183367729187, "text": "Ice is actually less dense than water, so in ice the molecules would be more spread out than in liquid water assuming that the frozen liquid is homogeneous, which it probably isn't. And yes, there is a difference in density between cold and warm water, but it only varies from about 999.97 g/dm^3 at 4°C to 958.4 g/dm^3 at 100°C (998.21 at 22°C) so it might be difficult to notice the difference. As a rule of thumb, when you cool something down it shrinks (of course water below 4°C is an exception to this rule), so the molecules in your juice will be more tightly packed when cold than when warm." } ]

[ { "id": "corpus-174089", "score": 0.7755758166313171, "text": "Well there are substances which behave as you describe, they are called amorphous. So something like butter. If you take it from fridge it is firm, if you let it warm up it becomes more and more soft. What separates water from butter in terms of solidifying is that water creates cristals while solidifying, while butter does not (at least on big scale). So in butter while you cool it particles have less and less energy, they come closer to each other, intermollecular interactions increase, it becomes gradually firmer. Water on the other hand while in appropriate conditions starts creating cristals in its internal structure. So this moment of transition makes bigger difference in terms of firmness. In liquid molecules are loosely bonded, while in solid molecules are firmly held in place. This is at least how I understand this.", "topk_rank": 0 }, { "id": "corpus-260316", "score": 0.7706528902053833, "text": "Short answer is no. For example, liquid methanol has a density of 0.786 g/cm^3, while solid methanol has a density of 0.791 g/cm^3. The reason ice is less dense than water is because of hydrogen bonding, not necessarily because it is polar (although without this polarity hydrogen bonding wouldn't happen). In liquid water each molecule is hydrogen bonded to approximately 3.4 other water molecules. In ice each each molecule is hydrogen bonded to 4 other molecules. This leads to more space between atoms in the ice crystal. [This picture should help illustrate; liquid water is on the left, solid ice is on the right.](_URL_3_) Hydrogen bonds are relatively weak, so the higher energy of the liquid phase means the atoms are moving around more-- hydrogen bonds are constantly breaking and reforming. However, in solid ice, there is less energy in the system so the hydrogen bonds are better at holding the atoms in place. If you'd like to read more about the structure of ice, [here's a link](_URL_2_).", "topk_rank": 1 }, { "id": "corpus-57425", "score": 0.7688318490982056, "text": "15-20 C isn't really cold. That's like room temperature to lukewarm. But most liquids become more viscous as the temperature decreases. Water does too. It's probably more noticeable in ethanol since it also has a lower surface tension and you can get it a lot colder before it freezes.", "topk_rank": 2 }, { "id": "corpus-305560", "score": 0.7674061059951782, "text": "Water is made up of a central oxygen atom that's very strongly bound to 2 peripheral hydrogen atoms. In the liquid phase, these water molecules are all jiggling and randomly moving around. Also, the hydrogens from one molecule can temporarily bond to the oxygens in other molecules, and this is called hydrogen bonding. As you cool the water, the molecules move around less and less. The molecules form a more ordered structure through hydrogen bonding, and end up being spaced farther apart than when they were in a liquid. This makes ice less dense than water. That's a simplified explanation; it turns out that this is a really complicated topic. Other substances that expand on freezing are silicon, gallium, germanium, antimony, bismuth and plutonium .", "topk_rank": 3 }, { "id": "corpus-108256", "score": 0.7639968991279602, "text": "Most liquids take up less space when they freeze into a solid. This is because, as you have pointed out, solids are typically denser than liquids. But water and ice are an exception - ice is *less* dense than liquid water. This is why it expands when freezing, and also why ice floats. The reason why is complicated, having to do with the crystal structure of ice and the hydrogen bonds the molecules form. Hopefully someone else can explain that part better than I did.", "topk_rank": 4 }, { "id": "corpus-190913", "score": 0.7635510563850403, "text": "Below 4°C, the hydrogen bonds between each water molecule become stronger and cause the matter to expand. As a liquid, water molecules are constantly moving (forming and breaking hydrogen bonds) resulting in less expansion and the molecules being jumbled up on top of each other. When frozen, water molecules take a more defined shape and arrange themselves in six-sided crystalline structures. The crystalline arrangement is less dense than that of the molecules in liquid form because the molecules don't get jumbled up on top of each other it actually creates space between them, which makes the ice less dense than the liquid water.", "topk_rank": 5 }, { "id": "corpus-53496", "score": 0.7597942352294922, "text": "C2H5OH (ethanol) vs H2O (water). Ethanol is alcohol. It does freeze, just at a colder temperature than water. Ethanol is a bigger molecule than water; the electron distribution is also more equal (but still favoring the -OH side of the molecule). Water is more polar, so the molecules are attracted to each other (like magnets). These things mean that the ethanol molecules don't get close enough together to form a solid until a lower temperature than water. You're probably talking about vodka in the freezer. Try moving to Minnesota and leave a bottle on your back porch... it'll freeze.", "topk_rank": 6 }, { "id": "corpus-35726", "score": 0.7581835985183716, "text": "Because alcohol's melting point is about -173°F (or -114°C), while freezers generally keep their insides about 0°F (or -18°C), so it stays totally melted inside the freezer. Water has a melting point of 0°C, so it will turn to solid (ice) in a freezer. Also, aluminum has a melting point of 660°C, so it remains solid even inside a relatively balmy fridge, and doesn't melt into your bowl that you've covered in foil :)", "topk_rank": 7 }, { "id": "corpus-117628", "score": 0.753224790096283, "text": "Its not that you *cant* compress liquid, its just that its very hard to do so with any result, some times you will turn that liquid solid, other times you wont depending on the substance. it depends on the substance, but many compounds are more dense when solid rather than liquid. water for example is *less* dense as a solid which is why ice floats.", "topk_rank": 8 }, { "id": "corpus-323070", "score": 0.7510157227516174, "text": "Ethanol is less dense than water on its own, but it is *soluble* in water so that when they are mixed it does not separate out like, say, oil. Since it is soluble, the two together essentially become a new \"unified\" liquid and the relative densities do not cause layering (like how dissolved salt or sugar does not separate out by density either). If I were to guess at what you are experiencing, it would be that you have ice in your drink, and the part at the top has simply been diluted more locally due to the melting ice.", "topk_rank": 9 }, { "id": "corpus-31368", "score": 0.7494974732398987, "text": "Ice is less dense than water. When it melts the liquid water takes up less space.", "topk_rank": 10 }, { "id": "corpus-286547", "score": 0.7479600310325623, "text": "Yes, a solid is almost always denser due to having a more organized structure that allows the molecules to pack together at maximum tightness. Water/ice is one of the few exceptions to this as you mention. This is in part because the strong hydrogen bonding interactions between the molecules in the liquid phase allow the molecules to sit very close together.", "topk_rank": 11 }, { "id": "corpus-186895", "score": 0.7469891309738159, "text": "Alcohol freezes at a much colder temperature (-115C if I remember correctly) That's why you store stuff like white wine in the freezer so itll be chilled", "topk_rank": 12 }, { "id": "corpus-287004", "score": 0.7464108467102051, "text": "Ice takes a [crystalline](_URL_0_) structure that causes the molecules to be spaced further apart than when they are in liquid form.", "topk_rank": 13 }, { "id": "corpus-292885", "score": 0.7464003562927246, "text": "There could be two different things at work, the first of which is that sugars and alcohols lower the freezing point of liquids. A typical can of soda or soft drink will have around 36 grams of sugar in it, so you can get a greatly reduced freezing point. The other is a phenomenon called [supercooling](_URL_0_) where a liquid is cooled bellow it's freezing point without actually turning into a solid, this is most common in things like pure bottled water because the ice crystals need some type of impurity to help them form. Supercooled fluids will [have a tendency to insta-freeze if you give them a shake](_URL_1_) or introduce an impurity.", "topk_rank": 14 }, { "id": "corpus-81790", "score": 0.7447862029075623, "text": "This was explained to me this way: H2O has a shape formed at about a 100 degree angle, so a very wide V. When it gets cold and approaches freezing, the molecules are not arranged in any particular way, and in fact, very much random. The wide angle V shape causes them to freeze together with a lot of open space between the molecules, making ice less dense than water.", "topk_rank": 15 }, { "id": "corpus-315303", "score": 0.7439663410186768, "text": "None that I'm aware of, the molecular spacing once a gas is formed is several orders of magnitude greater than in a liquid, hence the enormous density difference. With solids and liquids the case is not so straight forward - ice is the perfect example of a solid which will float on its liquid due to the arrangement of molecules within the solid.", "topk_rank": 16 }, { "id": "corpus-179485", "score": 0.7434321045875549, "text": "It has do to with what is the most favorable lattice formation (crystalline structure) for the atoms to arrange themselves in. In a liquid, the molecules can pass over each other and pack together to fill the volume. Similar to a gas, without expanding to fill the volume. In solids, the molecules have to arrange in a repetitive structure. For ice, this structure happens to have more space in between the molecules than in the liquid form of water. Since there’s more empty space, the solid is less dense than its liquid form.", "topk_rank": 17 }, { "id": "corpus-325339", "score": 0.7429242730140686, "text": "Colligative properties, my friend. The mixture of a solvent (here, water) and a solute (ethanol) will make a solution that has a freezing point below the solvent alone. The more solute there is, the more the freezing point is depressed, so beer will freeze before wine which will freeze before vodka, ignoring other solutes. If you had low-proof booze and got it cold enough, the solution would freeze. But the water would freeze out first, leaving behind a solution with a higher concentration of alcohol. Ta-da! You've fortified the booze without a still! The same phenomena is why you put antifreeze + water mix in your car radiator, put salt on the roads in the winter, and use rock salt (CaCl2) instead of table salt (NaCl) mixed with ice to make ice cream.", "topk_rank": 18 }, { "id": "corpus-161019", "score": 0.7428185343742371, "text": "As water solidifies into ice, water molecules arrange themselves into a crystalline structure [that looks like this.](_URL_0_) Because there's much more space between the molecules when they are arranged than when they're free to move as a liquid, there's also the need to occupy more volume to hold the same amount of molecules. This is also the reason why ice is less dense than water and floats. I hope this can answer your question!", "topk_rank": 19 } ]

[ { "id": "corpus-325423", "score": 0.6932543516159058, "text": "I thought this was actually a pretty good question.. Thermoregulation, i.e. producing heat in response to external stimuli, is usually associated with birds and mammals. However, according to [this](_URL_0_) article it sounds like there are some flowering plant species that are able to use an alternate pathway for respiration that allows for heat generation instead of ATP synthesis. This is actually really really cool. Maybe someone who knows more about this can chime in?" } ]

[ { "id": "corpus-159742", "score": 0.6578715443611145, "text": "Plants derive most of their mass from the air! CO2 (carbon dioxide) is converted into fuel and mass for the plant via photosynthesis. From their roots, plants acquire water and nutrients. Water is transitory in the ground, and thus the large amount of water used by a tree wouldn't cause a depression. And the nutrients acquired by the plant are in very minute quantities. So, in summary, plants get their mass from the air! Cool huh!", "topk_rank": 0 }, { "id": "corpus-79956", "score": 0.6575378179550171, "text": "Building on u/tears4lube's response, it takes energy to heat something. Different materials (water, or flesh, or tree, or dirt, etc) take different amounts of energy to raise their temperature. The lightning has an incredible amount of energy, which is why it's hot. The lightning flashes/strikes, and does not transfer enough energy in that amount of time to the human body (or whatever it strikes) to heat its target to reach the actual temperature of the lightning.", "topk_rank": 1 }, { "id": "corpus-268036", "score": 0.6575263738632202, "text": "\bFlames are more a combination of radiative heating and convective heating. The heating of the pot itself is conductive, from contact with the heated fluid (air) around it. The pot heats faster when there's contact with the flames not just because of the contact itself, but because contact means you're at a closer distance to the heat source. The flames are visible at all because they're energetic enough to radiate light, so clearly the flame is an illustration of where the hot part of the air is.", "topk_rank": 2 }, { "id": "corpus-121216", "score": 0.6572247743606567, "text": "The chemical reactions that power our cells are exothermic--they release heat. These reactions, combined, look like a big combustion reaction (read \"fire\"). So, roughly, the food you eat is burned *while dissolved in water* all throughout your body, and that's where your body heat comes from.", "topk_rank": 3 }, { "id": "corpus-172497", "score": 0.6571558713912964, "text": "What do you mean? Like greenhouses? They let in light and trap heat, allowing plants to grow in colder climates than they could otherwise.", "topk_rank": 4 }, { "id": "corpus-174236", "score": 0.6569181680679321, "text": "Absolutely. Alot of urban and downtown infrastructure generates alot of heat. NYC literally has underground steam pipes pumping hot steam around. Blacktop roads also contribute to heat patterns, and of course dense urban roads cause more contributing than sparse rural roads. And not to mention the cars on those roads.", "topk_rank": 5 }, { "id": "corpus-181363", "score": 0.6566359996795654, "text": "If you think of water, as we heat water, it doesn't just warm but it will boil at 100 Celsius. With any molecule, if you heat it enough, you will cause either a physical change like boiling, or chemical changes such as breaking links, reacting with other molecules. Something like an egg will have their proteins unfold, and refold into new forms, which hardens the egg. Vegetables will likely have their cell walls broken, and water content leaks out. Cell wall being what makes plants have a crunchy texture.", "topk_rank": 6 }, { "id": "corpus-259159", "score": 0.6565859317779541, "text": "[The process that generates heat is called \"cellular respiration\".](_URL_0_) You may be familiar with aerobic respiration, whose chemical reaction (in simplified terms) is C6H12O6 + 6O2 -- > 6CO2 + 6H2O + heat. This process releases 2.8 MJ per mole of glucose.", "topk_rank": 7 }, { "id": "corpus-1706237", "score": 0.6565510630607605, "text": "I really want to cultivate some indoor plants in my flat but anything I buy almost inevitably starts browning and losing leaves after few weeks. I expect this is likely because of the cold. We heat only for few hours every day but because the building is old and poorly insulated the heat escapes quite fast - so even if I make air warmer, the soil in pots is likely to stay at lower temps. I've had some plants where the roots have rotted away which I assume was due to water not evaporating from pots, so I've drastically cut down on watering. However that doesn't seem to improve the condition of the plants, and on top of that it makes me really uncertain about when to water.\n\nAny words of wisdom?", "topk_rank": 8 }, { "id": "corpus-58698", "score": 0.6563622355461121, "text": "Adding heat to an area often opens up blood vessels. When they're cold, they contract more. So by adding heat, you're effectively increasing blood flow to the area, which obviously contains white blood cells needed to fight off infection. This is why diabetics are prone to infection, especially in their feet, because of decreased blood flow to their feet", "topk_rank": 9 }, { "id": "corpus-52672", "score": 0.6563578248023987, "text": "As a Bio student right now, while I may not know the exact reasons, it seems to be those are ways to generate heat. Shivering and other excessive and fast movement generate body heat and may even cause cells to respire more which also generates heat as a by product. Basically its the body trying to balance its process of equilibrium and homeostasis.", "topk_rank": 10 }, { "id": "corpus-643826", "score": 0.6562480926513672, "text": "Apparently its the heat from your scalp that makes the roots process faster, but are there any other factors into which parts of the hair lighten faster?", "topk_rank": 11 }, { "id": "corpus-5069", "score": 0.6559054851531982, "text": "It depends upon the kind of pain. For muscle aches, heat causes blood vessels to relax and dialate. This means more nutrients are going into the area, promoting healing and carrying away toxins faster. For other sorts of pain - like a burn or an area swollen with infection, apply heat is a terrible idea. Cooling is effective as it causes blood vessels to clinch closed -and the problem is too much fluid in the area.", "topk_rank": 12 }, { "id": "corpus-250817", "score": 0.655635416507721, "text": "The sun warming your back is transferring thermal energy to you through infra-red radiation. In a vacuum, this travels at the speed of light. In different media, the speed of electromagnetic radiation is variable. Heat transfer through the other two methods - conduction or convection also strongly depends on the method. Conduction, for instance, is very slow across something considered to be an insulator such as air or wood which is why they feel warm to the touch. It can also be very fast in a good conductor such as gold, copper or diamond which is why they can feel cold to the touch as the thermal energy is rapidly conducted away. Incidentally, this is where the link between diamond and ice is claimed to come from. Convection depends on things like airflow and surface area. Blow on hot tea=cools down faster. TL;DR - there is no specific speed of heat, it depends on method and the specifics of what is transferring the energy.", "topk_rank": 13 }, { "id": "corpus-271926", "score": 0.6555310487747192, "text": "I am not a scientist, but I thermal images of different people smoking cigarettes in a laboratory setting to answer your question and you can actually see heat being drawn from their extremities (like fingers, toes, and ears). Smoking may distract you, and make you feel warm, but it is proved to reduce the heat from your extremities, if not your overall body temp.", "topk_rank": 14 }, { "id": "corpus-295179", "score": 0.655513346195221, "text": "The heat generated by smoking is tiny next to other sources, and all direct heat production by human civilization is insignificant next to the effect of CO2 production on the retention of solar heat. The smoke would, if anything, reduce solar flux to the ground, but in reality it is much too diffuse to have any effect. Cultivation, production of cigarettes, and shipping does cause some CO2 release through various types of energy use (cars, electricity) but tobacco forms a fairly small proportion of global agriculture.", "topk_rank": 15 }, { "id": "corpus-108223", "score": 0.6554945707321167, "text": "It does heat up, but you greatly underestimate how much energy is contained in heat. XKCD did a [write up](_URL_0_) of more or less your exact scenario.", "topk_rank": 16 }, { "id": "corpus-299553", "score": 0.6554688811302185, "text": "Yes, you can feel heat in space, heat can travel through space in the form of electromagnetic radiation. The frequency of that light depends on the temperature of the object, so cool objects (most things on earth) emit primarily infrared while the sun emits visible light. That's why you feel warm when you step in the sunshine, heat transfer is occurring through visible light (and some nonvisible light as well, primarily ultraviolet, which is why you need to wear sunscreen) edit: ultraviolet is only a small contribution as pointed out by gunner3210, most of the power transfer occurs in the infrared with a sizable contribution from visible.", "topk_rank": 17 }, { "id": "corpus-19239", "score": 0.655349850654602, "text": "Why do humans, who rely on heat, burn with too much heat? Obviously everything has tolerances for heat that it can and can't take. Exact tolerances depend on the species and even the breed. For example, huskies can't really handle the tropics, and chihuahuas can't really handle Alaska. The burning point of plants depends on the plants and the parts of the plant. Ferns, mushrooms, trees, tree leaves, etc. all have different burning temperatures.", "topk_rank": 18 }, { "id": "corpus-260411", "score": 0.654516875743866, "text": "Heat is produced as a by-product of all chemical reactions in our body. However, when the temperature in our surrounding drops, our body is able to upregulate the conservation and production of heat. Goose bumps are when the small smooth arrector pili muscles attached to hair cause the hair to be erect to slow the movement of air across skin, minimizing the loss of heat. Sweat also is not produced when the surrounding environment is cold. Muscles can also shiver, creating heat since cellular respiration is exothermic. Vasoconstriction of the arterioles under the skin also occurs, to keep more blood away from the skin and closer to the core of the body. Lastly brown fat tissue (present in babies, as well as people constantly in the cold, such as inuit tribes, but also activated by cold in [regular healthy people](_URL_0_)) is able to directly produce heat from fats by letting H^+ bypass the ATP synthase channel in the mitochondria and enter directly back into the matrix of the mitochondria.", "topk_rank": 19 } ]

[ { "id": "corpus-325424", "score": 0.7802873253822327, "text": "Yes! There are plants that produces excessive amounts of heat, referred to as thermogenic plants. They do this by uncoupling the electron transport chain to produce heat instead of ATP. I cannot think of specific species right now but I know that many of these plants use this heat to better disperse compounds that attract pollinators and I think there is also a plant that uses thermogenesis to melt snow around its flower." } ]

[ { "id": "corpus-2313860", "score": 0.7353255152702332, "text": "I have a plant that's having a hard time in this unusual summer heat and I was wondering how I might cool it. I thought of running a fan on it but... do fans actually cool things or do they just blow away the radiant heat it produces?", "topk_rank": 0 }, { "id": "corpus-267000", "score": 0.7157990336418152, "text": "The major source of heat is the release of chemical energy through cellular respiration! For example, glucose breaks down into carbon dioxide and water, but it also liberates heat.", "topk_rank": 1 }, { "id": "corpus-172370", "score": 0.7156951427459717, "text": "Trees and other plants cool down the space around them because water evaporates from their leaves. In order to evaporate, water molecules require energy. To get this energy, they \"take away\" heat from their environment, which creates a cooling effect!", "topk_rank": 2 }, { "id": "corpus-272403", "score": 0.715546190738678, "text": "Microbes secrete enzymes that break down the plant matter, eventually releasing single sugar monomers (like glucose) they can use. Breaking the bonds produces energy in the form of heat.", "topk_rank": 3 }, { "id": "corpus-159963", "score": 0.7079426050186157, "text": "The plant isn't shrinking, it's drying rapidly. Most of the volume of a plant is water, heat causes evaporation, that volume is now gone so the plant loses all of it's body. When you heat and cool a piece of metal all that material is still there from beginning to end.", "topk_rank": 4 }, { "id": "corpus-325423", "score": 0.7064498066902161, "text": "I thought this was actually a pretty good question.. Thermoregulation, i.e. producing heat in response to external stimuli, is usually associated with birds and mammals. However, according to [this](_URL_0_) article it sounds like there are some flowering plant species that are able to use an alternate pathway for respiration that allows for heat generation instead of ATP synthesis. This is actually really really cool. Maybe someone who knows more about this can chime in?", "topk_rank": 5 }, { "id": "corpus-172497", "score": 0.6990106105804443, "text": "What do you mean? Like greenhouses? They let in light and trap heat, allowing plants to grow in colder climates than they could otherwise.", "topk_rank": 6 }, { "id": "corpus-142010", "score": 0.6895092129707336, "text": "No, plants don't feel pain. Science hasn't found any evidence that plants feel pain, as they lack brains and a nervous system. It's agreed upon that you need those things for the more complicated sensations, such as pain. Some plants do respond to stuff, like Venus flytraps catching flies, but it's not the same thing. Plants are simple things, pain is too complicated of a response.", "topk_rank": 7 }, { "id": "corpus-274941", "score": 0.6883743405342102, "text": "I do a lot of work in the areas of physics and chemistry not so much biology but I can give you a general idea. When you break the chemical bonds in a chemical reaction it is either exothermic or endothermic meaning it either releases energy or absorbs it. I don't know specifics but my guess is whatever reacts with the nutrients makes an exothermic reaction which would release energy in the form of molecular kinetic energy, which in turn would transfer heat.", "topk_rank": 8 }, { "id": "corpus-313156", "score": 0.6880865097045898, "text": "All metabolisms do produce some heat. In larger fish/reptiles this can be enough to keep them noticeably warmer than ambient. They lack the complex thermoregulation systems that mammals have though, and may experience significant changes in core temperature during the course of the day.", "topk_rank": 9 }, { "id": "corpus-260430", "score": 0.6842662692070007, "text": "Every cell in your body produces heat as a byproduct of the various chemical reactions taking place, most prominently metabolizing sugar. It isn't evenly distributed (the more energy an organ is using, the more waste heat there is), but yes, your foot produces body heat too.", "topk_rank": 10 }, { "id": "corpus-103399", "score": 0.6834576725959778, "text": "The simplest answer I could give to this, the one I would tell an actual five year old is that plants don't photosynthesize from heat, which black would help retain, they photosynthesize from light using a chemical called chlorophyll. Chlorophyll is an important part of how plants create their energy and it is sensitive to and absorbs every spectrum of visible light except green, which it reflects. Which is why it's green.", "topk_rank": 11 }, { "id": "corpus-2311786", "score": 0.6817853450775146, "text": "Hey savage gardeners! Just wondering if anybody has experience with or recommends using plant heating pads or plant warmers of any kind for carnivores? I have two tropical pings, one is doing pretty well, the other almost died and I’m just trying to salvage leaves for propagation at this point and I’m wondering if maybe it’s just too dang cold in my house. I live in a very cold place. Does anyone recommend this? Maybe my plants would do better with heaters? Happy holidays all!", "topk_rank": 12 }, { "id": "corpus-274445", "score": 0.6810271143913269, "text": "Body heat is the accumulated heat of all the exothermic metabolic reactions happening inside cells. Animals are typically said to be warm blooded when the rate at which they generate this excess heat exceeds the rate they are capable of radiating it to the atmosphere. There is a more too it than that but the essence is to do with how metabolic rate interrelates to body surface area. To answer your second question the answer is Yes. Almost all metabolic reactions are concerned with processing material that is eaten. So almost all the heat generated is ultimately the by product of converting the foods you've eaten in to useful metabolic products.", "topk_rank": 13 }, { "id": "corpus-179102", "score": 0.680348813533783, "text": "Not an expert but I believe some carbon gets stored in the structure of the plant, which when burned releases that carbon, or when pressed and stored over many years turns to oil and when burned releases the carbon into the air.", "topk_rank": 14 }, { "id": "corpus-299130", "score": 0.6802548170089722, "text": "Plants are permeable to air. The air just seeps in.", "topk_rank": 15 }, { "id": "corpus-121216", "score": 0.6764739751815796, "text": "The chemical reactions that power our cells are exothermic--they release heat. These reactions, combined, look like a big combustion reaction (read \"fire\"). So, roughly, the food you eat is burned *while dissolved in water* all throughout your body, and that's where your body heat comes from.", "topk_rank": 16 }, { "id": "corpus-304804", "score": 0.6760309934616089, "text": "The heat is derived from chemical energy. The chemical energy accumulated when plants fixed carbon into sugars, fats, and proteins/amino acids is released in the body to do cellular work. This is called the **Krebs Cycle**, or the **[Citric Acid Cycle](_URL_0_)**. This heat is created more or less evenly throughout the body, however, not every part of the body is as efficient at removing the heat as others are. Cold blooded animals do not produce as much heat due to much slower metabolisms. They have slower metabolisms and are cold blooded because they lack cooling abilities, not heating abilities. **EDIT: Link**", "topk_rank": 17 }, { "id": "corpus-310259", "score": 0.675789475440979, "text": "Plants and other photosynthetic organisms also release CO2. Oxygen is produced in the process of turning water and CO2 into sugar. The plants then produce ATP through oxidative phosphorylation in other tissues, which releases CO2. This is why a sealed terrarium can function, as light is all that's needed to keep the plants alive, as water, oxygen and CO2 will all cycle through the plants.", "topk_rank": 18 }, { "id": "corpus-181363", "score": 0.6755049824714661, "text": "If you think of water, as we heat water, it doesn't just warm but it will boil at 100 Celsius. With any molecule, if you heat it enough, you will cause either a physical change like boiling, or chemical changes such as breaking links, reacting with other molecules. Something like an egg will have their proteins unfold, and refold into new forms, which hardens the egg. Vegetables will likely have their cell walls broken, and water content leaks out. Cell wall being what makes plants have a crunchy texture.", "topk_rank": 19 } ]

[ { "id": "corpus-325425", "score": 0.78227698802948, "text": "Generally no. The main reason disks get flatter is that they are dense enough for collisions between particles, which causes them to lose vertical speed and hence drop towards a flat disk. In a galaxy, the odds of even a single star colliding is very small, so the vertical velocity spread doesn't significantly change without a perturbing force." } ]

[ { "id": "corpus-285169", "score": 0.7426642179489136, "text": "No. While galaxies are certainly accelerating one way or another, the forces due to this acceleration are extremely minor compared to the forces of gravity within the galaxy. The orientation of a spiral galaxy is determined by the net angular momentum that the massive cloud of dust that became the galaxy happened to have. Since this angular momentum is conserved except when an outside torque is applied (which basically can't happen to the whole galaxy except maybe during galaxy collisions), the orientation of the disk remains constant.", "topk_rank": 0 }, { "id": "corpus-319003", "score": 0.742624044418335, "text": "There's no edge, the universe isn't moving in any direction, it's just increasing the amount of space between the galaxies. See the [FAQ](_URL_0_) for more.", "topk_rank": 1 }, { "id": "corpus-12566", "score": 0.7422731518745422, "text": "The super short answer is we don’t know. All we know is that the universe is getting less dense, and there is more empty space between celestial objects. Its also not doing so radially (from a center), but more just sort of in all directions. We know this through observation and measurement so we are sure its happening, we just havent worked out why. The common explanation is “dark matter/energy”. Which basically means energy/matter that we can’t see that just mathematically must be there in order for the expansion (and the masses of several galaxies) to make any sense.", "topk_rank": 2 }, { "id": "corpus-313643", "score": 0.7400002479553223, "text": "The average trend is that galaxies are moving away from each other. On small scales (e.g. nearby galaxies), your normal motion through space (from gravity etc) is in some sense \"stronger\" than the expansion of the universe, and so on a small scale you can get galaxies moving in all sorts of directions relative to each other. We even have galaxy clusters where a hundred galaxies orbit around a common centre.", "topk_rank": 3 }, { "id": "corpus-287524", "score": 0.7398713231086731, "text": "There is definitely evidence that dark matter is not symmetric: [Link](_URL_0_) But, gas is interacting, which causes it to lose energy and cool, whereas dark matter does not really. Angular momentum is harder to get rid of, thus the disk shape. So, the halos won't really flatten.", "topk_rank": 4 }, { "id": "corpus-325456", "score": 0.7386766076087952, "text": "There's clear evidence that the expansion is happening and that it's accelerating. If we assume this will keep going then eventually all galaxies become isolated from each other and something like a [heat death](_URL_0_) occurs. But no one knows if the expansion will keep on going. We don't even have a good theory for the acceleration yet.", "topk_rank": 5 }, { "id": "corpus-323314", "score": 0.7374014258384705, "text": "Just a side note. Don't think of distant galaxies as moving through space, because they aren't. Think instead of changes in geometry over time, because that's what's happening. When we talk about accelerated expansion, we're talking about the way the rate of change in geometry changes with time. The essence of it is that the distances between fixed points in the universe are increasing over time. Take any two points, measure the distance between them, then wait a reasonable amount of time — say a dozen billion years. Measure the distance again and you'll find that the distance has increased. The two points are not moving. But the distance between them is not fixed. So when viewed from a single point at a single instant, it appears that objects sitting out in space at those fixed points are receding from us, and that their speed of recession is proportional to how far away they are. But we know that isn't the case. It's just an optical illusion.", "topk_rank": 6 }, { "id": "corpus-308386", "score": 0.7368419170379639, "text": "You're thinking correctly. In fact, after a redshift of about z=2, the angular size of objects *increase* with distance! Galaxies look bigger in the sky the further out we look. Here's [a graph of angular scale](_URL_0_) as a function of redshift (~distance). The units on the y-axis are kiloparsecs per arcsec.", "topk_rank": 7 }, { "id": "corpus-250036", "score": 0.7362738847732544, "text": "The warp is almost certainly due to the gravitational effects of either a collision with or close pass by another galaxy. Galaxies often merge with each other, and it can take a long time for the disruptions to flatten out.", "topk_rank": 8 }, { "id": "corpus-300472", "score": 0.7348283529281616, "text": "Not sure about all the galaxies but you can read up on [the great attractor](_URL_0_).", "topk_rank": 9 }, { "id": "corpus-325006", "score": 0.7334280610084534, "text": "Some elliptical galaxies are, in fact, quite close to spherical, a sphere merely being a special case of an ellipsoid. Spirals just get all the attention, 'cause they're so purdy.", "topk_rank": 10 }, { "id": "corpus-325284", "score": 0.7295889258384705, "text": "According to my [calculation](_URL_0_), the difference in distance between the center and one edge of the Andromeda galaxy (one of the closest) means that we see the edges of its spirals about 2,900 years in the past relative to its center. this time scale seems almost irrelevant on a galactic level. so I would assume there is little warping from the width of the galaxy", "topk_rank": 11 }, { "id": "corpus-55208", "score": 0.7286514639854431, "text": "The expansion is still happening, but the immense gravity of two galaxies close(in astronomical terms) to each other has more of an effect. But there's also the reasoning that we don't really understand a lot of it yet, for instance, everything in this general area of the universe seems to be gravitationally effected by one extremely large mass that we don't know what it is.", "topk_rank": 12 }, { "id": "corpus-299470", "score": 0.7278177738189697, "text": "From the side, a (spiral) galaxy looks like a thin disk with lots of dark dust lanes in the disk, and a bright bulge in the middle extending above and below the disk. Some examples: [Sombrero Galaxy](_URL_3_) [NGC 4565](_URL_0_) [A galaxy with a warped disk](_URL_1_). Warped disks commonly result from close gravitational interactions with other galaxies, either dwarfs or major galaxies. The gravitational influence of the visitor tugs the disk out of shape, and the warp can remain for a few dynamical timescales after the interaction. Elliptical galaxies, like [NGC 1132](_URL_2_), look elliptical from any angle (though they may appear more circular or more elliptical depending on viewpoint).", "topk_rank": 13 }, { "id": "corpus-250209", "score": 0.7271408438682556, "text": "This is only the case if it is curved in certain ways, which as far as we know is not the way our universe is. If that were the case, we could perhaps see multiple copies of the same galaxy in different directions, but we don't see that. [This can be used to put limits on the dimensions of such curvature](_URL_0_), if it exists.", "topk_rank": 14 }, { "id": "corpus-311985", "score": 0.7259920239448547, "text": "The galaxies formation and evolution are still highly debated, but yes, it appears that their size change with time (while they keep roughly the same mass). This image shows a rough scenario of our current understanding of galaxy evolution. _URL_0_ If we don't consider galaxy mergers (of which you can see beautiful images on the Internet, and what will happen to the Milky Way and the Andromeda galaxies), the evolution of their star population is most certainly at the origin of these changes, even if it is not a clear-cut answer. The problem is that it is difficult to infer a clear evolution scenario from observations. Sources : _URL_1_ _URL_2_ _URL_3_", "topk_rank": 15 }, { "id": "corpus-322483", "score": 0.7258254289627075, "text": "Yes and no, respectively. Galaxies don't just sit there stationary - for the most part they're moving away from one another as the Universe expands, and then on top of that they have some additional motion as well. But they don't orbit around any common center. As far as we know there is no center of the Universe.", "topk_rank": 16 }, { "id": "corpus-312314", "score": 0.7255083322525024, "text": "For why the galaxy is flat - that's a commonly asked question and you should search previous posts or check the FAQ. Basically, angular momentum means that a disc is the furthest that a cloud of gas can collapse into. The spirals only represent like a 10% difference in density - there's plenty of stars in between them. They look so prominent because there are lots of bright new stars in them. What *causes* the spiral shape is actually a bit of an open question. Spirals come out quite naturally in a galaxy because the inner parts are orbiting faster than the outer parts, so any structure is going to be stretched out into a segment of a spiral. There may not be one single mechanism for making the spiral shape, because they come about so easily. But a common idea for the big \"grand design\" spirals is that they are density waves in the gas of a galaxy - kinda like sound waves - that are stirred up by interactions with nearby galaxies.", "topk_rank": 17 }, { "id": "corpus-318112", "score": 0.7245121598243713, "text": "Galaxy's can change shape. Especially during galaxy mergers, when one galaxy passes through another. Other self interactions are probably too small to notice and certainly not in real time. But that doesn't mean they are moving slower than your coffee! We are spinning around or own galaxy at a dizzying ~1/2 a million mph. And moving toward the Andromeda galaxy at~1/4 a million mph. Some day , ~4 billion years from now the will crash into one another and drastically change shape. Look up this stuff on _URL_0_.", "topk_rank": 18 }, { "id": "corpus-314160", "score": 0.7243289947509766, "text": "Most galaxies if left undisturbed should form spiral galaxies, and it's thought that these galaxies will eventually form elliptical galaxies as they age. Collisions are commonplace in the universe and cause a lot of the irregular and misshaped galaxies. Gravity from other galaxies nearby may cause the galaxy to not be spiral or elliptical, and form other shapes as well.", "topk_rank": 19 } ]

[ { "id": "corpus-325426", "score": 0.6248689889907837, "text": "I haven't kept up on the field, but there was a.ckmpany trying to grow them via vapor deposition processes to try and make semicondutor-sized wafers. Last I had heard they were making wafers on the inch or so scale, but I think they got derailed for the jewelry industry. Same deal with Gemesis (if I remember the name right). They do it with pressure chambers. I saw a talk by one of the founders and he had crazy baller jewelry." } ]

[ { "id": "corpus-544931", "score": 0.5935885310173035, "text": "I've been shopping around for an engagement ring with my fiancee, and we've decided to put down a deposit on a ring we really really like the look of. However we're a little nervous that we may have made a mistake. \n\nThe ring is certified by IGL and has been graded as colour: H and clarity: VVS1. Our reasoning when agreeing to go for this ring was that even if the clarity and colour are off by a couple of grades, then it's not too much of a big deal, as we really like the way the diamond looks. But, since committing to this diamond, we've done tons more research and are starting to get nervous that IGL may not just be off by a couple of grades, but the certificate could actually be completely off. This is mostly down to horror stories we've read, where diamonds are 4-5 grades lower in colour and clarity when graded by IGL. \n\nIs it really common for IGL to be 4/5 grades off when it comes to colour and clarity? Does anyone know if less known/trusted certification bodies like IGL are likely to be inaccurate when it comes to cut? Surely they can't get the cut and carat wrong too?\n\nCan anyone provide any guidance or suggestions as to what we should do? I feel super stupid as I didn't ask to view the diamond under a magnifying glass, but we did take a look at the diamond outside (under direct sunlight though) and again we thought it was beautiful. We'd rather loose our deposit then pay for a diamond which isn't worth anywhere near as much as we've agreed to pay. We're just not sure what to do. Please help!", "topk_rank": 0 }, { "id": "corpus-2559117", "score": 0.5935484766960144, "text": "My boyfriend and I have started looking at engagement rings and I mentioned maybe moissanite because they’re beautiful and cheaper and that way I could get my dream style but a bit more budget friendly. \n\nI found a place that sells them here in Toronto and after seeing them in person found the perfect style (oval solitaire moissanite with a lab grown diamond band) at the top of our budget. My boyfriend is hesitant because it has a lab grown diamond band and he’s heard they don’t last over time and are easy to damage especially because there would be no warranty. I am just hoping for some advice on care of moissanites (specifically with lab grown diamond bands) after purchase and if you’ve had any problems and if so how do you go about getting them fixed specifically if you lose a stone or even just if I need it resized? Hearing from people with first hand experience and not just people trying to get a sale has been hard to find so any and all advice is appreciated!", "topk_rank": 1 }, { "id": "corpus-527813", "score": 0.5935197472572327, "text": "We currently have 3DM CAD models for our diamond jewelry, and we need a 3D artist to set up the materials and environments for rendering them in Rhino. We're using Brazil for Rhino, but if you have experience setting up HDR equirectangular environment maps in Maya, 3DS Max, VRay, etc., the process is very similar. We'd need HDR environment maps that are optimized for diamond jewelry set in precious metal settings. Also, material settings for platinum, white gold, yellow gold, and rose gold. We have a computer (Windows 7, 6-core Intel i7) in our office with all the necessary software (Rhino, Brazil, Photoshop) installed on it, we just need someone with these particular artistic skills to come in and spend a day or two setting up the renderer. We're located in midtown near Herald Square, and we're very flexible as far as what hours you'd be able to come in. We'd pay $80 an hour for someone with the requisite skills, and we'd like to establish a working relationship with someone who can do this type of work for us in the future.\n\nOur current ring renderings look like this:\n\n\n\nThey're okay, but can certainly be improved on. I've been trying to do it myself for a while, but there's a pretty steep learning curve, and it's really difficult to find the right balance necessary to render platinum/diamond jewelry. In tutorials like this one, for instance, the render looks great, because the gold and the gemstones are different colors, but when you try and do that in platinum, it looks really fake. We've made some progress in figuring out the technical side, but really need someone to assist on the artistic side.\n\nAs far as who we are, here's an AMA we did:\n\n\n\nIf you're interested, send me any examples you have of rendering work that you've done in the past, especially jewelry, or scenes with a lot of metallic and glass materials.", "topk_rank": 2 }, { "id": "corpus-2225150", "score": 0.593433678150177, "text": "Just found this Engagement Ring on Ebay, it comes from Hong Kong.\n\n\n\nIs it a real lab grown diamond and is the ring made out of real platinum, or is it likely that I will be scammed? Thanks for the help in advance", "topk_rank": 3 }, { "id": "corpus-309003", "score": 0.5934185981750488, "text": "The [W54 warhead](_URL_0_) used in the [Davy Crockett nuclear rifle](_URL_1_) is the smallest nuclear weapon ever created, with a yield between 10 and 20 tons of TNT. This is thought to be close to the minimum size possible, at least with the technology and materials we use. You need a certain amount of fissionable material to achieve a chain reaction, and while this amount can be reduced with the use of explosives to compress the material, it's hard to balance between getting a significant yield at all and not getting a much higher yield.", "topk_rank": 4 }, { "id": "corpus-313823", "score": 0.5933829545974731, "text": "Worse. While diamond is incredibly *hard*, it is not particularly *strong* (like steel). Hardness is the ability of a material to resist abrasive wear and tear, meaning that diamond is perfect for use in cutting tools and abrasive applications such as polishing. Strength is the ability of a material to resist high impacts and is clearly more important in a swordfight when you have swords clashing against eachother. I suspect that the diamond would most likely just shatter on impact.", "topk_rank": 5 }, { "id": "corpus-2309946", "score": 0.593251645565033, "text": "I’m not sure if this is the right subreddit to post this in but I’m going to give it a shot! \n\nMy boyfriend and I have been dating for 2.5 years and we’ve spoken about marriage A LOT. He’s asked me off hand whether I want a lab grown diamond/real diamond and he’s taken my ring size but that’s about it. \n\nI don’t know how to drop hints about what type of ring I would want without feeling like I’m pressuring him to engage. I want it to be a surprise but I don’t want to hate the ring he gives me. I’d love any suggestions anyone might have.", "topk_rank": 6 }, { "id": "corpus-307533", "score": 0.5929852724075317, "text": "There are physical limitations to how small you can make a nuclear bomb. The major one is the [critical mass](_URL_1_) of the fissile material. This is on the order of 10kg for Plutonium warheads and higher for uranium. The critical mass is the absolute minimum amount of material you need for a spontaneous nuclear chain reaction to occur if you just have a chunk of the material sitting there. You can use a few tricks like compressing the material with a shockwave created by conventional explosives, but of course adding conventional explosives to your weapon also makes it larger. In reality, you're not going to get too much small than the ~10kg size. Also, keep in mind this 10kg is just for the fissile material and doesn't include the casing, detonator, etc. A nuclear warhead the size of a bullet or hand grenade is pretty much in the realm of science fiction, but [nuclear artillery shells](_URL_0_) were apparently a thing.", "topk_rank": 7 }, { "id": "corpus-283384", "score": 0.5927929878234863, "text": "For their width the limits would be the [Roche limit](_URL_1_) and the edge of the atmosphere (roughly 10 000km on Earth). This is because if it is outside the Roche limit, the rocks used to make the rings win't break up and will stay as what they were before, and inside the atmosphere they will gradually slow down due to drag and fall down to Earth. The vertical thickness of the rings won't be very much at all. I don't know the exact equation for the thickness, but Saturn's rings are only [~10m thick](_URL_2_). [This paper](_URL_0_) is on planetary rings if you want to read more into it. Hope I helped :) EDIT: The paper I linked talks about the thickness far better than I could on pages 24 and 25.", "topk_rank": 8 }, { "id": "corpus-87650", "score": 0.5926843285560608, "text": "It's not as big a deal as you think. The diamonds they revealed are not jewelry grade. \"The Siberian branch of Russian Academy of Sciences said that the Popigai crater in eastern Siberia contains \"many trillions of carats\" of so-called \"impact diamonds\" — good for technological purposes, not for jewelry, and far exceeding the currently known global deposits of conventional diamonds.\" I don't think these type of diamonds will affect DeBeers much. [source](_URL_0_)", "topk_rank": 9 }, { "id": "corpus-986559", "score": 0.5925299525260925, "text": "I have a six inch rig with a 14mm female hole, so I need a 14mm male enail setup. I looked at mini nail and thought that looked good. Help.", "topk_rank": 10 }, { "id": "corpus-287006", "score": 0.5924277901649475, "text": "You're scaling things the wrong way. Don't worry about the *size* of the golf ball, worry about its *mass*. The earth has a diameter that's about 3 * 10^8 times larger than that of a golf ball. But the earth's *mass* is 1.3 * 10^26 times greater. That means the force of gravity the golf ball exerts is 1.3 * 10^26 times weaker than that of the earth, so something would have to be 1.14 * 10^13 times *closer* to earth than the moon is to experience a similar strength attraction, which ends up being about 30 microns. For one, this means your golf ball is not *nearly * small enough to be a stand in earth. You simply can't get something close enough to it to experience any significant amount of gravity.", "topk_rank": 11 }, { "id": "corpus-1192009", "score": 0.5922207832336426, "text": "I've entered the world of engagement ring shopping and I'm a little overwhelmed, as I expected. I've read about what a \"good sapphire\" should look like, but I'm having trouble really differentiating between stones. \n\nI've been looking on The Natural Sapphire Company's website and I think these two are pretty good and within my price range, but I'd like a second opinion from someone who knows more than me about sapphires (pretty low bar here tbh):\n\n1: \n\n2: \n\nShe wants an oval shape and a diamond halo setting, so I'm thinking the stone shouldn't be more than .75 carats or it may look overly large. \n\nI appreciate any advice I can get!", "topk_rank": 12 }, { "id": "corpus-1659468", "score": 0.5920013785362244, "text": "Q-Carbon is an allatrope of carbon that is harder than naturally-occurring diamond.\n\n&gt; The process uses a high-powered laser pulse, similar to that used in eye surgery, lasting approximately 200 nanoseconds. This raises the temperature of the carbon to approximately 4,000 K (3,700 °C; 6,700 °F) at atmospheric pressure. The resulting liquid is then quenched (rapidly cooled); it is this stage that is the source of the \"Q\" in the material's name. The degree of supercooling below the melting temperature determines the new phase of carbon, whether Q-carbon or diamond. Higher degrees of cooling result in Q-carbon, whereas diamond tends to form when the free energy of the carbon liquid equals that of diamond.\n\nIt seems to me that it could be printed on an SLS printer that had the ability to \"quench\" the material fast enough.", "topk_rank": 13 }, { "id": "corpus-2590995", "score": 0.5917264223098755, "text": "The value for every synthetic share that is covered will be put into the value of every certified share.\n\nIf there are currently 70 million certified shares and 140 million synthetic shares. The true market cap is 42 billion. \n\nThat’s very simple math. If true the current price is $600.\n\nTLDR: hodl\n\nThis is not Financial advice.", "topk_rank": 14 }, { "id": "corpus-301434", "score": 0.5916294455528259, "text": "You can calculate it quite easily. The length of a carbon-carbon bond is [154 picometres](_URL_0_), or 0.154 nanometres (if both carbon atoms are sp3-hybridised). Most polymers are grown from alkene monomers (2 carbon atoms), so the length of the polymer chain is equal to 2*N*C-C*cos(32.25 degrees): N - degree of polymerisation C-C - carbon carbon bond length 32.25 degrees - deviation of C-C bond from backbone axis. If you're dealing with a sp2-hydridised backbone, or some mixture, you'll have to adjust the equation a little, and if the portion of the monomer in the backbone is longer than 2 carbon atoms you just need to alter the initial coefficient. For a polyethylene polymer for instance, N = 50, length ~ 13 nm, for N = 3839, length ~ 1000 nm.", "topk_rank": 15 }, { "id": "corpus-886875", "score": 0.591394305229187, "text": "By big i mean: \n7.5 inch and above, 19cm and above. \n \nHad bad experiences and wasted some money so far... \nHad a silicone toy that did not smell right. Dont believe that it was actually 100% silicone. \nI did found a NS Novelties Colour one that i would like to order. \nBut i am not sure if they are 100% Silicone. \n\nSuggestions?? ^^", "topk_rank": 16 }, { "id": "corpus-302966", "score": 0.5913863182067871, "text": "Carbon is ideal because it is the fourth most common element in the universe and can covalently form chains of itself (called [catenation](_URL_2_)). The four valence electrons also allows it access to a wide range of geometric forms, such as sp^3 tetrahedral (diamond), sp^2 planar (graphene), or sp linear (sort of, alkynes definitely exist but polyynes like carbyne are often unstable). This allows you to make *a lot* of stable structures out of just carbon. The main drawback to silicon is that it just doesn't catenate with itself well. Long chain silicon molecules are highly reactive with water, and often spontaneously decompose. Also aromaticity for silicon doesn't work in the same way as carbon. You can barely make a [benzene-like silicon molecule](_URL_2_), much less a sheet of slicon-based graphene (which wouldn't even be flat).", "topk_rank": 17 }, { "id": "corpus-1219049", "score": 0.5912648439407349, "text": "So I'm still currently looking for a stone as I had to postpone the purchase due to the pandemic. Some of the stones that I looked at some two months ago are no longer available and, therefore, I would appreciate any opinions on the following stones:\n\nCriteria - Round Cut, around 1 Carat, SI, F Color or above, and \\~$5k\n\nFrom James Allen:\n\n \n\n \n\n \n\n \n\nI notice the last one has chips on the side and I was wondering how significant these inclusions are.\n\nFrom Blue Nile (while I like Blue Nile, I wish they had better clarity on their photos and videos)\n\n \n\n&amp;#x200B;\n\nI would greatly appreciate your opinions on any of the above stones or a suggestion for another similar stone.", "topk_rank": 18 }, { "id": "corpus-152755", "score": 0.5911800265312195, "text": "Its not the size of a pingpong ball. Its a singularity. A size so small that it has no width no height no diameter.", "topk_rank": 19 } ]

[ { "id": "corpus-325427", "score": 0.7269308567047119, "text": "Galaxies are big, planets are small. Do some simple math, a galaxy is maybe 100,000 light-years across, or more, at a billion light years away that's a ratio of 1:10,000. Now consider a planet, even a huge planet like Jupiter is only about 0.5 light-seconds in diameter. So even at 4 light-years distance, the closest any other star is to us, that's a ratio of about 1:240,000,000. Planets are very, very tiny, there's just no way with current telescopes of resolving them into anything other than a single point. Worse, because planets are near stars the enormous brightness difference means that the light of the planet gets lost in the glare of the star. With advanced techniques it may become possible to cancel out the glare of the star and resolve the planet but such technology is still being developed today and may be years or decades away." } ]

[ { "id": "corpus-8132", "score": 0.6905381679534912, "text": "There are people looking for life on Mars. It's one of the things that the rovers are doing, and the next one [has it as one of the main goals](_URL_0_) (though they don't expect to find current life, just past). The problem is that we can't exactly put rovers on a planet orbiting Alpha Centauri, due to the distances involved, so we can't do that type of search on planets outside our solar system. Even reaching mars is a serious technical challenge, so we've not started looking as seriously at Europa or other possible incubators of life.", "topk_rank": 0 }, { "id": "corpus-151827", "score": 0.6902174949645996, "text": "Ok, you have been tasked with searching planets for life. Oh boy, where do you even start? You barely even have any telescopes. You live on Earth. All life on Earth is carbon-based and relies on water. This is an absolute fact and you know it to be true, because you're one of those squishy life-forms. You did the math, and *maybe possibly* life *could* also be based on silicon and eat hydrofluoric acid. What planets do you search first?", "topk_rank": 1 }, { "id": "corpus-56485", "score": 0.6901727318763733, "text": "You have a good point. You can also ask what can be considered living. We only understand life as it is on earth. Thus we know wat we are looking for on these goldilocks planets. That being said, there may be an object in the middle of a planet that could be classified under our definition of living organisms. Those 7 characteristics of life. But we have no idea how other live an arise from something other that C, N, O and H molecules, and these molecules can only be used generally as animals on earth use it. Because of that we also know a certain temperature for these are needed with certain conditions. Thus we believe there is a bigger chance of finding life on planets with similar conditions. Hope this helps:)", "topk_rank": 2 }, { "id": "corpus-115912", "score": 0.6899048686027527, "text": "It's generally not just one continuous long exposure, it's multiple exposures layered on top of each other digitally that add up to the final image. And because the stuff that Hubble is looking at is all so far away, the motion of the telescope as it orbits doesn't mess up the image.", "topk_rank": 3 }, { "id": "corpus-238863", "score": 0.6898750066757202, "text": "There's not anything to see one light year away. The Very Large Telescope has an 8 meter lens and can see 300 nm wavelength, meaning we could see resolve 400,000 kilometers at that distance.", "topk_rank": 4 }, { "id": "corpus-167249", "score": 0.6897696256637573, "text": "It's the latter. We only know life on earth -- life as we know it. It's possible there could be exotic forms of life elsewhere, but we have no idea what it would look like or how to find it. So we focus on the life we understand, because that's what we're best at finding. To some degree though, we know the chemicals our life is based on are probably some of the best for \"life\". Carbon has specific properties that make it very nice for replication and other life functions. Silicon is very similar to carbon, which is why you often hear about people looking for \"silicon based life\" -- it's the most likely other element that could produce organisms that follow similar mechanics as ours.", "topk_rank": 5 }, { "id": "corpus-245010", "score": 0.6896103620529175, "text": "According to my astronomy professor (who specialized in searching for extraterrestrial life), one thing we will look for life on other planets is oxygen gas. This is because free oxygen is unstable and combines easily with other atoms/molecules. The only process we know of that produces oxygen in large amounts, and the only reason we have a lot of oxygen in our atmosphere, is plant life. More info: _URL_0_", "topk_rank": 6 }, { "id": "corpus-835099", "score": 0.6895724534988403, "text": "So I am on the telescopes topic, and I was wondering why we can’t tell apart two distant stars at almost the same angle in the sky, and what a telescope needs to achieve so that we can resolve smaller angles when we look through it. \n\nI have some ideas but cannot put it into words.\n\nAny help would be appreciated", "topk_rank": 7 }, { "id": "corpus-271456", "score": 0.6895179152488708, "text": "For Earth based telescopes, the largest aperture belongs to Gran Telescopio Canarias (GTC) at 10.4m. Assuming (incorrectly) that this telescope is [diffraction limited](_URL_0_), and that Earth was at aphelion, Mars at perihelion and opposition (closest possible approach), GTC would theoretically be able to resolve objects down to about 3.2 kilometers across (~2 miles). I wouldn't care to guess what its actual limit would be due to being seeing limited, better ask an astronomer. (Note that these numbers were calculated for green light with a wavelength of 500nm). If the Earth and Mars were on opposite sides of the sun (with a viable viewing path between them) this number would change to ~23.5km (~14.6 miles) for GTC. For Hubble with its 2.4m optics, these numbers would be ~13.9km (8.6 miles) and ~101.9km (~63.4 miles) respectively.", "topk_rank": 8 }, { "id": "corpus-296216", "score": 0.6894851326942444, "text": "A mass spectrometer would be pretty high up there. To clarify, it would provide enormously valuable information about the composition of the universe outside of our solar system.", "topk_rank": 9 }, { "id": "corpus-832894", "score": 0.6894330382347107, "text": "I know that unlimited magnification is impossible, but I'm curious to know what other limiting factors there are. I presume that the light disperses/degrades after such a distance that there's a limit as to how much detail you would be able to be able to resolve, so being able to see life walking around on the surface (for example) would never be able to happen, even if you could achieve enough magnification.", "topk_rank": 10 }, { "id": "corpus-261395", "score": 0.6894214153289795, "text": "You can use pulsars to do something like that, although that would only work within a single galaxy. In fact, the Voyager probe has a map to Earth using pulsars for triangulation.", "topk_rank": 11 }, { "id": "corpus-298743", "score": 0.6893941760063171, "text": "When we look farther away, we're looking farther back in time. If we look far enough, we're looking at a time when the universe was much hotter and denser. Beyond a certain point, the universe was so hot and dense that it was full of ionized plasma, and light couldn't propagate. The plasma cooled and formed hyrogen about 400,000 years after the big bang, and that is the farthest we can see (which appears as the cosmic microwave background). If we can drastically improve our neutrino detection capabilities we could see farther back, because neutrinos travel unimpeded through basically everything.", "topk_rank": 12 }, { "id": "corpus-191277", "score": 0.6892455816268921, "text": "We cannot, this is one of the greatest questions ever bestowed upon mankind, there are many theories; some of which being an empty void of dark matter/dark energy. But we truthfully have no idea what is beyond the observable universe. We can only see up to 13.8 billion\\~ light years with current tech, the James Webb Telescope will surpass this by hopefully a minuscule fraction more, albeit, it will be used to see objects we have already seen via the Hubble but at a higher level of clarity than we have ever been able to achieve before. Anything beyond is simply so red-shifted that we will never know, this is also a scary thought, the universe is theorized to be expanding at a FASTER rate than we previously predicted and it is speeding up, for all we know there could be absolutely anything out there, things that we cannot even begin to comprehend.", "topk_rank": 13 }, { "id": "corpus-299901", "score": 0.6891777515411377, "text": "That planet's gravity might be able to perturb the orbits of the other planets. We could notice this with telescopes. This method is how ~~pluto~~ Neptune was discovered.", "topk_rank": 14 }, { "id": "corpus-145969", "score": 0.6889972686767578, "text": "They can't. However, if you know that a planet orbits at a certain distance from a star of a certain temperature, then you can calculate the surface temperature of the planet, which might be good for Earthlike life.", "topk_rank": 15 }, { "id": "corpus-236517", "score": 0.6889926791191101, "text": "The spectrum around 1420MHz is critically important to astronomy. Hydrogen is very common, so we can use 1420MHz to image all sorts of heavenly objects. It's logical to assume that any civilization curious about the universe will also build radio telescopes for this purpose. So, they'd already have a bunch of ears to the sky listening at that frequency, regardless of whether or not they're looking for ET signals. The general idea is that a digital data signal from intelligent life would behave much differently than anything we normally see out there.", "topk_rank": 16 }, { "id": "corpus-59011", "score": 0.6889498233795166, "text": "It's very expensive to explore there. We have already sent submersible craft to different parts of the ocean floor, but it's just very expensive to do. So unless there is some specific reason that you are searching for something, there needs to be a reason to justify the cost.", "topk_rank": 17 }, { "id": "corpus-320731", "score": 0.6882606744766235, "text": "From [_URL_0_](_URL_1_) > The surface of the Earth is whizzing by as Hubble orbits, and the pointing system, designed to track the distant stars, cannot track an object on the Earth. The shortest exposure time on any of the Hubble instruments is 0.1 seconds, and in this time Hubble moves about 700 meters, or almost half a mile. So a picture Hubble took of Earth would be all streaks.", "topk_rank": 18 }, { "id": "corpus-1190905", "score": 0.68797367811203, "text": "\n\nI don't know many astronomy terms, but will I be able to see deep sky objects such as the Orion horse nebula? Will I be able to see Jupiter or even the Andromeda galaxy?\n\nThank you for any answer!", "topk_rank": 19 } ]

[ { "id": "corpus-325428", "score": 0.7122864127159119, "text": "This here should answer your question _URL_0_ The genioglossus muscle is responsible for \"protrud(ing) the tongue as well as depressing its center\"" } ]

[ { "id": "corpus-245796", "score": 0.6764671802520752, "text": "Mostly with two muscles: 1) The [**levator labii superioris alaeque nasi**](_URL_3_), which is a tiny muscle, not a Harry Potter spell. It means \"elevator of the upper lip and wing of the nostril\", referring to the slip of muscle that attaches to the [alar cartilage](_URL_2_). It's the longest muscle name, which is kind of cool. It attaches to the bone right below the eye and runs down to the alar cartilage and part of the upper lip. When it contracts it pulls the corner of the nostril up and out. It also [allows you to snarl](_URL_0_). 2) The [**nasalis**](_URL_4_), a muscle that lies on the bridge of the nose and inserts into the alar cartilage. The [**dilator naris**](_URL_1_) is specifically what's doing most of the flaring. It's going to pull the top of the nostrils up and out.", "topk_rank": 0 }, { "id": "corpus-1664270", "score": 0.6763631701469421, "text": "I've been mewing for a year now and just recently, managed to position my tongue in such a way that gives constant pressure to both the roof and my molars. Is this how it's done?\n\nI've also felt subtle changes when my top and bottom teeth are against each other. It's the small subtle changes, such as my teeth feeling out of place for the first time, that make me wonder if I'm doing it correctly", "topk_rank": 1 }, { "id": "corpus-1388298", "score": 0.6762134432792664, "text": "I know it has been asked a million times, but it's always asked specifically for suicide, so the only answer people get is that it probably won't kill you. I'm just wondering how tough it is to completely remove your tongue, or at least a part of it. I believe I've read, and learned a bit from experience, that the tongue isn't very sensitive to pain. Is it like this all the way through? Would it be easier to bite hard at first and maybe hit the jaw upwards, or would taking it slow work just as well? Is it easy enough that anyone who wanted to could do it?", "topk_rank": 2 }, { "id": "corpus-1030535", "score": 0.6751985549926758, "text": "It happens immediately. I can sometimes push through to the point where my throat eventually opens, but I want to learn how to open my throat under pressure. Thanks!", "topk_rank": 3 }, { "id": "corpus-1032849", "score": 0.6749661564826965, "text": "Because when i need to collect saliva all my tongue goes low to sweep up. Do u have some advices or exercices for maintaining the back of the tongue on the palate and only move the tip ?\nSry for my bad english, hope it was understandable!", "topk_rank": 4 }, { "id": "corpus-112914", "score": 0.6749418377876282, "text": "If there's not enough space in your mouth you may be unable to keep your tongue out of the way. People who have to wear retainers or other dental hardware sometimes get a lisp.", "topk_rank": 5 }, { "id": "corpus-1997733", "score": 0.6736947298049927, "text": "I have a tongue tie. I can't make my tongue out from my mouth. If I try it strains for days. She said I am tugging too much not actually licking. \n\nPlease give me some tips.", "topk_rank": 6 }, { "id": "corpus-109378", "score": 0.6736432909965515, "text": "Muscle memory. Like playing a piano or hitting a baseball, your \"speech muscles\" (tongue, lips, jaws etc) get better at remembering certain movements with practice. With enough practice, the muscle movements become almost reflexive, making it more effortless to produce the desired speech sounds over time.", "topk_rank": 7 }, { "id": "corpus-55940", "score": 0.6735068559646606, "text": "It's not like your mouth is working independently of the brain and then the brain has to interpret what's going on. Your brain is the boss here and initiates the action. When you breathe your brain tells your diaphragm to contract. This expands the lungs and draws in air through your windpipe and mouth/nose. When you swallow food your brain is telling a different set of muscles to contract, specifically the ones in the esophagus.", "topk_rank": 8 }, { "id": "corpus-149110", "score": 0.6728666424751282, "text": "Kinda close to your jaw? This is your salivatory gland going into overdrive and \"pulling a muscle\" from the strain of trying to produce enough saliva to protect your tough and taste buds. Some people get it one one side, some get it on both", "topk_rank": 9 }, { "id": "corpus-247370", "score": 0.6727269887924194, "text": "In and out through the cheek muscle? No biggie right?", "topk_rank": 10 }, { "id": "corpus-67985", "score": 0.6720442771911621, "text": "I can tell you why *I* lisp, if that will help. There is a flaw in the musculature of my tongue, on the leading edge about a centimeter from the tip. When I go to make a S sound in the ordinary way, air leaks through the gap that the flaw leaves, makes a distinct hiss. It took me years to learn another way to form sibilants that sounded better.", "topk_rank": 11 }, { "id": "corpus-99539", "score": 0.6719100475311279, "text": "Sticking your tongue out or biting your lip while concentrating is not really that weird. Michael Jordan was famous for his tongue sticking out while going up for a dunk. It is an example of what’s called motor overflow or motor disinhibition. It happens sometimes when our brains are working really hard at something. Normally, the brain keeps the brakes on the parts of the body it doesn’t want to move. However, when we concentrate really hard on a tough task, sometimes the brain lifts the brakes on other parts of the body (most often the face, lips, tongue, etc.) making them move without our control. As we get older our brains get better at controlling the brakes (inhibition) and the motor overflow goes away most of the time, but some people still have this happen when they are grown ups. There are studies that show it is more common in people with ADHD.", "topk_rank": 12 }, { "id": "corpus-176841", "score": 0.6715514659881592, "text": "It’s really hard to inhale when your muscles are all contracted, but contracting all or a lot of your muscles is what happens when you lift a heavy thing. You inhale, the lift, and as part of the lifting, you exhale. If your mouth is closed, and your jaw is also clenched, their in your mouth builds up in your cheeks until you think to let it out. Because this happens kind of naturally, we also learn to do it on purpose to coordinate our breathing and exertion.", "topk_rank": 13 }, { "id": "corpus-189775", "score": 0.6715114712715149, "text": "The bolas you've formed to swallow is too large and stretching out the muscles of your esophagus as it travels down your throat. Edit to add: The throat is a tube with muscles that can squeeze or relax but no muscles that open the throat wider. So what happens is each section of the throat widens because the section above it squeezes a football shaped pocket of food down like getting the last glob of toothpaste out by squeezing the tube from the very bottom and working it out. The tongue is what kicks off the process. If the ball of food in your mouth is too large, the ball working its way down stretches the muscles as it passes through the tube.", "topk_rank": 14 }, { "id": "corpus-295174", "score": 0.67149817943573, "text": "Because normally, our airways are open unconsciously, with the epiglottis standing strait up, allowing air to flow in and out. When we swollow, the muscles in our throat push on the epiglottis, closing the larynx, guiding the food to the esophagus and stomach. So, if we were to allow saliva or other fluids to just slide down, without swallowing, it wouldn't be guided into the stomach, it would be guided down our bronchi and lungs, since the airway wouldn't close. Here's a [picture](_URL_0_) to clarify, hopefully Source: 3rd year med student", "topk_rank": 15 }, { "id": "corpus-114283", "score": 0.6714799404144287, "text": "Part of the function of your tongue is to roll up the food that you are chewing into a ball (called a bolus) that can be easily swallowed in one gulp. So while you chew it is constantly moving and churning the food. This process is not always perfectly coordinated with your jaw movement.", "topk_rank": 16 }, { "id": "corpus-2559516", "score": 0.6706649661064148, "text": "I (22F) have had tongue thrust for most of my life. I had braces when I was 13-15, for the second time, because I knocked a tooth out on my bottom teeth and we had to use braces to “close the gap,” so to speak, where that bottom tooth had been. So I also have a slight overbite. \n\nAnyway, since getting my braces off 7 years ago, a slight gap has emerged between my bottom and top teeth. It’s not terribly noticeable because of the overbite, but still. I wear top and bottom invasalign retainers NIGHTLY and I try to remain conscientious of where my tongue is resting and how I swallow every day. Of course, I’m sure when I’m hyper focused on something, or I’m sleeping, my tongue will still thrust between my teeth.\n\nI have a nice smile otherwise, but:\n\nGiven the information above, will my tongue thrust continue to widen the gap between my top and bottom teeth?\n\n\n\nEDIT: the whole thing honestly wigs me out, especially since I don’t have the sort of money to afford surgery or even therapy.", "topk_rank": 17 }, { "id": "corpus-174644", "score": 0.6705567240715027, "text": "Yeah basically. When you swallow, you create a *bolas* (a ball of food or water). Then you start *parastalsis* where a sequence of muscles involuntarily push the ball down. If the ball is too large—yeah it hurts. But it doesn't stop. It keeps traveling down stretching your throat.", "topk_rank": 18 }, { "id": "corpus-55531", "score": 0.6705129146575928, "text": "It's caused by two activities fighting for the same bit of brain to process them. When biting your lips or tongue, or sticking your tongue out, you suspend motor activity, minimizing movement, hence interference. Edit: [sauce](_URL_0_)", "topk_rank": 19 } ]

[ { "id": "corpus-325429", "score": 0.7380640506744385, "text": "As the National Lightning Safety Institue says : \"Swimming pools are connected to a much larger surface area via underground water pipes, gas lines, electric and telephone wiring, etc. Lightning strikes to the ground anywhere on this metallic network may induce shocks elsewhere.\" _URL_0_ However they do not explain really more than that." } ]

[ { "id": "corpus-137947", "score": 0.7005318999290466, "text": "It depends on the path the bolt takes through the body. A lightning bolt that travels from a person's butt to the ground through the leg might not be fatal. A bolt that travels through the head and the heart is much more likely to be fatal. Lightning doesn't travel in a straight line, and for some lucky individuals, the path the lightning travels through the body misses the vital organs.", "topk_rank": 0 }, { "id": "corpus-314982", "score": 0.6972323656082153, "text": "In someone who survives a lightning strike, most of the electricity doesn't pass though the body, it stays on the surface. The body is a better conductor then unionized air, but once the current has reached the ground, the surge of current will ionize the air around your body and form a better path then your body. If most of the current passes through your body, you will end up with severe internal burns. If the channel is through your heart or your brain, you're dead right away, and no matter what you're going to have serious long-term consequences.", "topk_rank": 1 }, { "id": "corpus-313101", "score": 0.6940537095069885, "text": "The immediate-death effect of being struck by lightning is cardiovascular. The bolt essentially acts like a defibrillator. If a person's heart is still beating after being struck, they will likely be fine. The route the bolt takes through the body (ie, through the chest, or not) will determine if the person's heart is affected. Most other injuries from being struck by lightning are thermal injuries (both internal and external). The path of the bolt through the body as it makes its way to ground will determine that.", "topk_rank": 2 }, { "id": "corpus-1899132", "score": 0.691382646560669, "text": "Can i meditate on the ground ( Grass ) when it is raining and thundering? \nIf the lightning hit the wet grass ( while i am on the ground ) \nis there a chance i will get shocked or die?", "topk_rank": 3 }, { "id": "corpus-152868", "score": 0.6907490491867065, "text": "The fear is that if lightning strikes your home and hits a water pipe it could electrocute you while you shower since water is a conductor of electricity. The odds are low.", "topk_rank": 4 }, { "id": "corpus-31967", "score": 0.6903730034828186, "text": "the reason you die from electrocution is it is an ongoing, continuous, current. The current will immobilize an muscle tissue it passes through, keeping it contracted for as long as the current is present. This includes your heart and lungs, to name a few. So basically you die because it stopped your heart / breathing / etc. A lightning strike, is pretty fast, lasting only a split second. Can still kill you but the chances are lower.", "topk_rank": 5 }, { "id": "corpus-21594", "score": 0.6902351975440979, "text": "When lightning hits the ocean, the discharge spreads over the surface of the water. Any fish/human near the surface will be electrocuted. Edit: humans are also better conductors than fish so the damage will be more substantial.", "topk_rank": 6 }, { "id": "corpus-124717", "score": 0.6900365948677063, "text": "[According to Don MacGorman, a physicist at the National Severe Storms Laboratory in Norman, Oklahoma: “Basically lightning stays more on the surface of the water rather than penetrating it. That’s because water is a reasonably good conductor, and a good conductor keeps most of the current on the surface.”] (_URL_0_). Also see [THIS] (_URL_1_). And [this old thread] (_URL_2_)", "topk_rank": 7 }, { "id": "corpus-27244", "score": 0.689720869064331, "text": "Lightning wants to get to the ground and it wants to do that through the first thing it can reach. So houses are often built with a system to collect lightning that would strike the house and funnel it into the ground. It moves the electricity through your metal pipes. So showering during an electrical storm exposes you to some risk of becoming the ground for the lightning.", "topk_rank": 8 }, { "id": "corpus-60006", "score": 0.6894444227218628, "text": "xkcd did a post about this a while ago: _URL_4_ If you're swimming close enough to get shocked you'll likely get hit directly, since it strikes the highest object... Unless you're completely underwater.", "topk_rank": 9 }, { "id": "corpus-249058", "score": 0.686374843120575, "text": "No. Terminal velocity is dependant on you weight and air resistance. The waterfall is very soon going to break into droplets that will fall much more slowly than you. Even if you position your body as to offer maximum air resistance your gonna fall at around 200km/h while a droplet falls around 36km/h. Attempting ot swim upwards (as opposed to trying to position yourself to augment your air resistance) in that scenario would probably reduce your air resistance and make you fall faster.", "topk_rank": 10 }, { "id": "corpus-76064", "score": 0.6857303380966187, "text": "My pool I supervise at has the water tank and filtration system underground. It can be struck by lightning which would feed into the actual pool and do harm. That's why we evacuate when its lightning outside even though it's indoor.", "topk_rank": 11 }, { "id": "corpus-99395", "score": 0.6831817030906677, "text": "Water is a good enough conductor that electricity mostly just travels along the surface. As a result, fish must either be really close to the lightning or touching the surface to be electrocuted.", "topk_rank": 12 }, { "id": "corpus-253874", "score": 0.6826239228248596, "text": "Very interesting question. Harmful Algal Blooms are a problem for swimmers. But I would bet the hurricanes affect would result in a dilution of the toxins concentration to a dose that would be a negligable risk.", "topk_rank": 13 }, { "id": "corpus-182860", "score": 0.6813469529151917, "text": "Being close to the sun doesnt kill you instantly, it kills you very *quickly*. In theory, if you could expose yourself to the sun for a *very* short amount of time, you would be fine. Lightning is very hot, but it is also gone very quickly.", "topk_rank": 14 }, { "id": "corpus-66599", "score": 0.6809787750244141, "text": "The lightning will take the path of least resistance through the human body. If that happens to be through or over the skin, missing important organs (especially the heart) then it's survivable, although you will likely come out with some burns and of course enough burns can kill you by themselves. Electricity is always most lethal to the heart, as it keeps its timing using electrical impulses", "topk_rank": 15 }, { "id": "corpus-150646", "score": 0.6806767582893372, "text": "Since the other answers are not helpful at all, I'll give it a stab. I don't understand it super well but if I'm wrong someone please correct me. Only the immediate vicinity is effected. As with any substance, however, saltwater has resistance. That means that the farther away from the point where the lightning struck, the \"weaker\" the electricity is, because it had to face more resistance. That's why the entire ocean doesn't become \"electrocuted\" when lightning strikes. However, if you were just a few feet away from where it struck, you'd feel it.", "topk_rank": 16 }, { "id": "corpus-265340", "score": 0.6804074048995972, "text": "It shouldn't really affect anything other than the surface of the water. Basically lightning stays more on the surface of the water rather than penetrating it. Water is a reasonably good conductor, and a good conductor keeps most of the current on the surface. If there is any penetration of the water column, that water directly hit will vaporize and I imagine some bacteria that occupied the vaporized water would die. But I doubt you're looking at a large area die off.", "topk_rank": 17 }, { "id": "corpus-303879", "score": 0.6794986724853516, "text": "It's possible, but improbable. The probability goes up significantly if your shower is on the roof, and you're the highest point on the roof. So the moral is don't shower on the roof with a short-shower in a lightning storm.", "topk_rank": 18 }, { "id": "corpus-1077269", "score": 0.6793720722198486, "text": "i'm guessing it's because maybe the saltwater acts like a big resistor only letting a bit through. either that or the person in the water would have to be 'grounded'. a g.i. joe PSA told me to get out of the water when it's storming, and i know saltwater is a better conductor than fresh water. right?", "topk_rank": 19 } ]

[ { "id": "corpus-325430", "score": 0.6922176480293274, "text": "what about the water moisture put out by fuel cells? I've seen a bus running on fuel cell and the exhaust looked like steam locomotive. I've been on the streets of Manhattan in July when the temp is 100F and humidity is 100% and its feels like hell. If all the vehicles are putting out as much moisture as the bus it will feel like a steam bath... or will it?" } ]

[ { "id": "corpus-278889", "score": 0.6575993895530701, "text": "_URL_0_ This is a CO2 scrubber used in anaesthesia, as you can see it is pretty small. It is obviously very different from what you'd need for the purpose you suggest though. This would be saturated very rapidly by a car. A human exhales about 4% CO2, With a minute ventilation of roughly 5L that is 200ml of CO2/min. If you estimate a gas consumption of 0,6L/10km and approximate the carbon content to 12/14 by weight, that gives 514g of carbon being burnt every 10km, yielding 1885g of CO2. At roughly 2g/L, driving 1km will produce 1000 times the amount of CO2 as breathing for 1 min, or about 16h 40min worth of breathing. That would consume several such scrubbers. So, _with this type of technology_ it would be a hopeless project. You'd have to switch scrubbers every 300m or so, and the actual carbon dioxide release from producing the scrubbers would probably be larger than the amount scrubbed by a significant margin.", "topk_rank": 0 }, { "id": "corpus-2459565", "score": 0.657439112663269, "text": "Just recently rediscovered this, I’ve had an aversion to diesel for some time, though in the early 90’s I was infatuated with VW diesels. No intentions of going back to ICE for most of my transportation needs but my Model 3 doesn’t do everything.\n\nAnyway I am having trouble making comparisons of renewable diesel vs gasoline. Particularly comparisons in identical vehicles. For example the same model pick up offered with diesel and gas variants. Any sources would be appreciated. \n\nI haven’t lost hope in Rivian or Tesla but if substantial gains can be had with excess capacity why not? America is up to its ears in pick up trucks.", "topk_rank": 1 }, { "id": "corpus-1729526", "score": 0.6569576859474182, "text": "The allowable hybrid energy is going to increase eventually from 2MJ per lab. When do you think that will be? \n\nAlso, when the allowable energy is increased, wouldn't it be appropriate to start brake harvesting from the front brakes as well? It makes sense to do it because in reality most of the braking energy is expended by the front brakes, which means a lot more energy can be recovered and increase the fuel efficiency. If energy is allowed to be harvested I would assume that would also mean that the cars will then have electric FWD. Would the weight of a front axle offset the benefits of the extra available power?", "topk_rank": 2 }, { "id": "corpus-1385845", "score": 0.6565463542938232, "text": "Obviously when flying, weight is a major issue and battery-packs aren't suited for this. However, it seems like this is the perfect opportunity for hydrogen fuel cells. The Toyota Mirai can go over 300 miles with just 32.3 gallons of compressed hydrogen, for example? So what's preventing hydrogen-fuel cell planes from being more mainstream as a greener alternative?", "topk_rank": 3 }, { "id": "corpus-1630215", "score": 0.6560804843902588, "text": "I bought a 2000 Honda Civic EX about a year and a half ago. The engine was blown so I had it replaced, at that time it was better than just buying a new car I did not have the money. Anyways the car runs really well no problems aside from the bad gas mileage. I get about 200 miles per full tank from driving street and freeway. I called the mechanic that replaced the engine and they've repeatedly told me that it is normal but isn't that super low? My car has 11.9 tank size and I basically get 16 miles per gallon.", "topk_rank": 4 }, { "id": "corpus-46666", "score": 0.655650794506073, "text": "Fuel is generally a string of carbon atoms with two hydrogen atoms attached to each one. To make it into CO2 and heat you have to mix it with oxygen. So CH2 + 3O - > CO2 + H2O. Carbon weighs 12 units, hydrogen weighs about 1 unit and oxygen weighs 16 units. So from the above formula we can see that 14 units of fuel and 48 units of oxygen turns into 44 units of CO2 and 18 units of water. This is just rough estimations and the exact numbers varies on the fuel and the combustion so we round that x3.1 to an even x3 to account for the extra hydrogen and oxygen atoms we find in real fuels. So the extra weight of CO2 emissions comes from the oxygen that is being consumed in the combustion.", "topk_rank": 5 }, { "id": "corpus-171611", "score": 0.6550032496452332, "text": "Most gasoline cars are very inefficient, turning most of the chemical energy into heat. I don't have any studies to site but if I remember correctly, cars only use about 20-30% of the energy stored in gasoline for forward motion whereas power plants (which can operate in more ideal situations) are more like 40% efficient at turning chemical energy into heat and then into electricity. This doesn't even include the energy lost to breaking a car which can be elleviated with many hybrid cars having regenerative breaking For comparison, electric cars can be 80-90% efficient at at storing and then turning electric energy into motion: _URL_0_", "topk_rank": 6 }, { "id": "corpus-242658", "score": 0.6541299819946289, "text": "According to the Department of Transportation in 2010 [PDF WARNING], [buses emit about 33% less CO2 per passenger per mile](_URL_0_). Note that buses are on average about 28% full, and at full capacity buses save much more. This data is pretty old so both cars and buses are more fuel efficient now, but I'd imagine the relative savings are similar, especially since hybrid or fully electric buses are becoming more common. I'm speculating now, but I'd imagine as a second-order effect increased bus ridership would decrease emissions even further by reducing traffic, meaning quicker routes with less time standing.", "topk_rank": 7 }, { "id": "corpus-1385825", "score": 0.653766393661499, "text": "Here in Germany SUVs aren't as popular as in the US. Extreme gas prices and higher taxes prevent people from buying them, so as a owner I sometimes get mocked for its high consumption and unnecessity.\n\nSo today I contradicted by saying I could tow heavier trailers and I got back the car would need to tow a tanker trailer full of gasoline... so I did the math:\n\nMy first generation Hyundai Santa Fe is allowed to tow **2240kg** (=4938 lbs). If you assume roughly 500kg for the empty trailer, this means I can carry approximately **1700kg** (=3748 lbs) of extra fuel, which at a density of 719.7 kg/m3 = 0.026 lb/in³ = 6.073 lb/US gal = 7.29 lb/imp gal (according to wikipedia\n\nMy car on average, using an economical driving style, consumes 11l/100km which equals 21.38 mpg (US) or 25.68 mpg (UK), but we have to assume the comsumption is higher when towing a trailer. As this trailer is very heavy, but gets lighter I assume this would cause a consumption of far more than 20 liters/100 km in the beginning and something like 15l/100km when the trailer is nearly empty. This is just a woolly estimate, but I would assume 20 liters/ 100km (=11.76 mpg) gets the job done: \n\n2422l / (20 l/100km) = 12110 km = 7525 mi \n\nAccording to Google Maps (saying 11.000 km in distance) I could drive to Wladiwostok without refilling, crossing russia in its full width or driving from Vancouver to Mexico City (one way approx. 4800km = 2983 mi) and back again, the possibilities are endless!\n\n... but there is one downside: because of high taxation gasoline isn't very cheap over here and at a current price of 1.55€ per liter it would cost 2422*1.55=3754.10€=5224$ ... well that's about the same my car is worth...\n\nedit:grammar", "topk_rank": 8 }, { "id": "corpus-748835", "score": 0.6536087393760681, "text": "i have a diesel powered 1900cc car\n\nIn city i usually do 12 km/l (28 mpg)\n\nRecently I got a bluetooth obd adapter and i am reading the consumption. When I am driving normally, i get the same mileage i was getting before from the on board computer. But if i drive without pressing the throttle (clutch, 1st, clutch, 2nd, clutch, 3rd, and so on, only keeping the engine idle) the ODB gives me insane mileage, like 40 km/l (95 MPG)\n\nIs that accurate? Seems impossible to use this much less gas. Ok, i am driving at 45 km/h (30 mph) in 5th gear at 900 rpm, but this difference in mileage is insane.", "topk_rank": 9 }, { "id": "corpus-254607", "score": 0.6531621217727661, "text": "I don't think any of the commenters so far have addressed the equal partial pressures aspect of your question. I believe the answer to your question is still yes however. Thinking of two boxes with equal fuel and and equal amount of oxygen, the one that also contains a bunch of nitrogen or other inert gas will see a slower rate of combustion due to the fact that the inert gasses have to be heated up too at the point of the flame. Their excess heat capacity will sap energy from the chemical reaction and slow it down. In internal combustion engines, the unavoidable addition of nitrogen into the mix is a significant drain on efficiency.", "topk_rank": 10 }, { "id": "corpus-303832", "score": 0.652805507183075, "text": "Oxygen and carbon atoms are (very) roughly the same mass. The carbon comes from the fuel, but the oxygen mostly comes from the air. So for every atom of carbon you take from the fuel, you take two atoms from the air. Hence you'd expect the final mass of CO2 to be about 3 times that of the fuel. This won't be perfect, because the fuel isn't all carbon (although hydrogen weight a lot less than carbon), because there's probably some oxygen in the chemical make-up of the fuel, and because carbon and oxygen are only very roughly similar in mass. But about 3 kg CO2 per 1 kg of jetfuel is what you would expect from a back-of-the-envelope calculation.", "topk_rank": 11 }, { "id": "corpus-285546", "score": 0.6526695489883423, "text": "A company in Arizona, called Fluidic Energy, is doing some pretty exciting research on Metal-Air-Ionic-Liquid (MAIL) batteries. They won an ARPA-E grant, and have already been field-testing some of their battery designs. The MAIL batteries would eventually cost about the same as a lead-acid battery, but would store enough energy to drive a car over 400 miles on a single charge. There are other companies doing similar research, but I have heard the most about this one. _URL_0_", "topk_rank": 12 }, { "id": "corpus-1356669", "score": 0.6526462435722351, "text": "I have recently started messing around with hybrid rocket engines and was wondering about the difference between using oxygen and nitrous. I have been using oxygen and was wanting to know if nitrous was a better oxidizer and it's price compared to oxygen. The store in my town that sells oxygen said you need a medical license to get nitrous, so I wanted to see what your opinions are and see if you know if it's possible to obtain nitrous without a medical license, also I live in Ohio so it may be different in other states.", "topk_rank": 13 }, { "id": "corpus-2011748", "score": 0.6525719165802002, "text": "It's a negligible amount, but it's still less. This does not apply for carbureted vehicles. Engine braking also wears more on your car, but this is still a fact.", "topk_rank": 14 }, { "id": "corpus-187543", "score": 0.6524215340614319, "text": "The RON represent the level of compression of the fuel, but natural gas is a gas and not a liquid like gasoline/petrol. & #x200B; So even if natural gas have an higher energy/mass than gasoline (about 15% more), it also have a terrible energy density or energy/volume (about 0.1% of gasoline). & #x200B; So ya you can compress natural gas more than you compress gasoline, but you gonna have a LOT less natural gas in your cylinder than you could with gasoline. This mean you will have a lot less energy available with natural gas. The reason is that on a car the volume is really important, you can't have super large cylinders to use more natural gas. In a power plant, it's the other way around. You can make your combustion chamber larger and the difference in mass that you need to transport, become a more important factor and in that case Natural gas is more efficient.", "topk_rank": 15 }, { "id": "corpus-300004", "score": 0.6523904800415039, "text": "You can. A cylinder of 200 cubic feet of hydrogen costs around $60 and 200 cubic feet of oxygen is around $50. Each of those contains ~500 moles of gas. 2 hydrogen cylinders + 1 oxygen cylinder will produce 1000 moles, or around 18 liters, of water for only $170. If you bought your gas by the truckload instead of the cylinder, it might be a little cheaper, but still a lot more expensive than just buying a truckload of water.", "topk_rank": 16 }, { "id": "corpus-2763927", "score": 0.6519090533256531, "text": "Good night my lovely people =)\n\nI am writing my master thesis in Freiburg, Germany. The subject of the master thesis is fuel cell powered bicycles. and the comparison of those with battery bikes. I have created a survey to help answer a few questions that have risen and to help to make an educated guess with external feedback.\n\n\n\nIf you could be so kind to answer my little survey, I would be very grateful to you all. Every answer helps me a lot =)\n\nWish you all a nice night and good riding 😬\n\n\\-Leonardo-", "topk_rank": 17 }, { "id": "corpus-303278", "score": 0.6515570282936096, "text": "Yes, that's the first law of thermodynamics. The reaction of H2 and O2 to water takes the same amount of energy in both directions. But due to heat losses/the second law of thermodynamics, neither the fuel cell or electrolysis cells would ever be 100% efficient. So there's little point in using electrolysis in producing hydrogen to put into a fuel cell, where your end goal is getting electrical power. But fuel cells can still be useful if you produce your hydrogen by some other means (for instance, directly from sunlight using clever chemical catalysts that we're currently doing a lot of research into). The point here is that chemical compounds serve as very good forms of energy storage, and that fuel cells have the ability - in principle at least - to produce electrical energy much more efficiently from them than combustion does.", "topk_rank": 18 }, { "id": "corpus-23304", "score": 0.6514899730682373, "text": "Oxygen isn't the fuel, it's the *oxidizer*. You need the O^2 in the air you breath in order to burn sugar and fat for cellular energy, and the waste product of burning sugar is carbon dioxide and H2O. The carbon from the fuel has to go somewhere, and we breath it out as CO2.", "topk_rank": 19 } ]

[ { "id": "corpus-325431", "score": 0.7547956109046936, "text": "do you mean like allotropes? Carbon can have several allotropes including buckyballs, graphite, and diamond, and more. _URL_0_ Other elements can exhibit allotropy _URL_1_" } ]

[ { "id": "corpus-318611", "score": 0.7163514494895935, "text": "Yes! They do exist, here's the most known example: _URL_0_ Often diagrams of it will depict two of the hydrogens as \"connected\" together which the Carbon like this: _URL_2_ The reason for this is in how the orbitals manifest, essentially, it's more like a CH3+ ion that's coupled with a H2 molecule. The reason this system of bonding can exist is that the other hydrogens share some of the bond energy in that through conformational changes, different hydrogens will be the \"bonded hydrogen molecule\" at any given time in an atomic game of hot potato (who get's to be electron deficient): _URL_1_ The reason the \"4 bonds only\" mantra is always touted is that usually, the higher or special bond configurations cannot be accessed so it's easier not mention or deal with them.", "topk_rank": 0 }, { "id": "corpus-322856", "score": 0.7162445783615112, "text": "It's more that carbon is such a flexible atom when it comes to making molecules. You can do so many things with it because it can take on so many different valencies, make so many different kinds of bonds, and arrange itself into so many different molecules. Metals typically do not have the same level of flexibility as carbon.", "topk_rank": 1 }, { "id": "corpus-322713", "score": 0.7161174416542053, "text": "We do not know and have never observed such life. Chemically, carbon is incredibly versatile in ways that other atoms simply cannot compare such as forming long chains and branches with itself (and other atoms like nitrogen) in complex shapes. While nature is generally more creative and subtle than we are, it doesn't look very likely.", "topk_rank": 2 }, { "id": "corpus-305698", "score": 0.7133991718292236, "text": "As others stated, it might help if you refer to a specific source stating it to give context to the question. Also keep in mind that an _element_ is not necessarily one, distinctive material. There can be different [allotropes](_URL_1_) for a given element, and they have different physical and chemical properties. For example, diamond and graphite are two allotropes of carbon. Ozone (O₃) and molecular oxygen (O₂) are two allotropes of the element oxygen. [Sulfur has many allotropes](_URL_0_) with slightly different melting points.", "topk_rank": 3 }, { "id": "corpus-72498", "score": 0.7126634120941162, "text": "I'm no expert but, Carbon has four valence electrons which means that it can take in four electrons which makes it possible to bond to a lot of shit. That diversity in shit-bonding allowed for more complex shit to be created and life needed a lot of different shit to bond to exist. That's why science fiction sometimes says that there could be silicon life forms, because it, too, has four valence electrons.", "topk_rank": 4 }, { "id": "corpus-318266", "score": 0.7101254463195801, "text": "I'm not aware of anything occuring naturally. But, you could put certain elements under pressure, and raise the temperature such that one is in a solid state while another is in a gaseous phase. To force the solid one to be lighter than the gas would be tricky. You would have to look at the triple point of both elements and design an experiment appropriately. I think in nature you aren't going to see this for the simple fact that gaseous elements tend to only exist with very low density, while solids have high density. I wouldn't expect to find it naturally occuring in any environment.", "topk_rank": 5 }, { "id": "corpus-280669", "score": 0.7090291976928711, "text": "Yes, but regular atoms are the most stable and common. You can make \"atoms\" about of muons and positrons, for example.", "topk_rank": 6 }, { "id": "corpus-314669", "score": 0.7090134620666504, "text": "Sure. Just wait long enough. The stable state of carbon under ambient conditions is graphite, meaning that all other forms will spontaneously decompose to graphite, eeleasing energy. This process ia very, very slow, though. But given enough time all diamonds at any temperature and pressure you could live through will convert to graphite.", "topk_rank": 7 }, { "id": "corpus-273059", "score": 0.7088057398796082, "text": "Not all *compounds* can be found in all states (as they often decompose under certain conditions), but under the right conditions you can get any element into any state. In fact, most of the periodic trends you probably learned about in general chemistry (including for metals like iron), are actually gas-phase properties. All those electron configurations they teach you? Gas phase electron configurations, not necessarily the most accurate for solid metals. All of those ionization energies and electron affinities? Those are measured for gaseous atoms as well.", "topk_rank": 8 }, { "id": "corpus-253267", "score": 0.708510160446167, "text": "I think the only difference is the context. Generally compounds (e.g. TiO2) have poly-morphs and pure elements have allotropes.", "topk_rank": 9 }, { "id": "corpus-324271", "score": 0.7077920436859131, "text": "Carbon is capable of forming stable chains of essentially arbitrary length and complexity. No other element does so in the same way. Silicon can form similar structures but they're much less stable and nothing else really comes close. Complexity is fairly essential for anything you'd call life.", "topk_rank": 10 }, { "id": "corpus-134415", "score": 0.7070956826210022, "text": "The color is called an *emission spectrum*. There are patterns, but they're not very simple from element-to-element: it has to do with how much energy it takes to 'excite' an electron in that type of atom. > Is there a way to predict it for new elements? Yes, by doing particle physics to calculate the gaps between energy levels in that atom. That being said, there are probably no more naturally occurring elements than those already observed - the periodic table has no remaining gaps and elements of higher number than those already discovered are extremely unstable.", "topk_rank": 11 }, { "id": "corpus-189876", "score": 0.70535808801651, "text": "Most of our DNA and cell structure is carbon, yes. In each molecule of bio-material, a majority of what you are is carbon by weight. And yes, it is a theory that life could also exist based on other elements like silicon because it creates the same number of bonds in a molecule as carbon does, and so it would behave in a similar way", "topk_rank": 12 }, { "id": "corpus-245800", "score": 0.7053176760673523, "text": "Be careful not to apply the rationale of Lewis dot structures, which are all about octets and the like, to metal structures. Metals do not have distinct atomic orbitals to consider, but instead broad [*bands*](_URL_0_) of energy levels. Achieving noble gas configuration turns out to pretty much never happen in metals in solid phase. (The concept doesn't really have any meaning.) Instead, the structure of a metal is based upon its crystal structure. The most intuitive way to think about this is to imagine how you can best pack spheres into a small area. It turns out that a hexagonal pattern (also called hexagonal closeness packing) is the most optimal amount you can get. Being very close together allows for the largest amount of overlap between the individual metal atom and its neighbors.", "topk_rank": 13 }, { "id": "corpus-302478", "score": 0.7050482034683228, "text": "_URL_1_ _URL_0_ Diatomic Carbon turns out to form a double bond but is highly unstable so we never really see it. Some transition metals can form quad bonds with d-orbital electrons.", "topk_rank": 14 }, { "id": "corpus-319666", "score": 0.7036296725273132, "text": "That's the pheynl group - the most basic [aromatic structure](_URL_2_). The delocalized nature of aromatic structures lends it stability - and more stable molecules are more prevalent; that's probably why you encounter it often. Aromaticity is not limited to six-membered carbon rings - there are many with heteroatoms, such as [pyridine](_URL_3_). Non-aromatic six-membered rings do occur though - see [cyclohexane](_URL_0_), and the common sugars such as [glucose](_URL_1_) and [sucrose](_URL_4_).", "topk_rank": 15 }, { "id": "corpus-834225", "score": 0.7031205296516418, "text": "I know this has been observed with electrons and buckyballs (60 carbon atoms) using the “two slit” experiment. I remember reading a while back that it was replicated using a 100 atom object. Has anything larger been attempted? Is there a theoretical maximum? Is it possible that everything exhibits this behavior and the probabilities just sort of balance out into Newtonian physics?", "topk_rank": 16 }, { "id": "corpus-270325", "score": 0.7020864486694336, "text": "[This article](_URL_0_) does an analysis on some transition metal and actinide species with high bond order (ditungsten and dimolybdenum in fact are listed as species which can be interpreted as possessing a sextuple bond). It also suggests that there should be no species with bond order larger than six using the atoms below Z = 100. It may still be possible for some elements to display septuple bonding or higher, especially in the 8th period of the periodic table, but chances are we won't be able to find that experimentally for a very long time, and reliable calculations for ultraheavy elements are extremely computationally intensive. It's also important to note that the very notion of bond order isn't completely set in stone. It can be defined in more than one way, and I'm not sure there's any experimental technique that will return a direct measure of how bonded two atoms are.", "topk_rank": 17 }, { "id": "corpus-320431", "score": 0.7020115256309509, "text": "The Carbon atom has four valence electrons allowing it to be very versatile for chemical bonding. Plus, it's just very abundant in the universe.", "topk_rank": 18 }, { "id": "corpus-292637", "score": 0.7019271850585938, "text": "Think of \"element\" as meaning \"possible configurations of subatomic particles\". \"Configurations of subatomic particles found in nature\" is a subset. Also, all of the elements we synthesize in labs probably exist in stars, constantly being formed and decaying. They just aren't stable enough to make it out of the star.", "topk_rank": 19 } ]

[ { "id": "corpus-325432", "score": 0.7547169327735901, "text": "Fruits have lots of other molecules in addition to sugar. One type of molecule that is responsible for the aroma/taste of fruit is [esters](_URL_0_). Esters are small, volatile organic molecules that, depending on the specific ester in question, have the characteristic smell of a particular fruit." } ]

[ { "id": "corpus-304009", "score": 0.7169672250747681, "text": "A lot of something's flavor is actually contributed by the olfactory receptors in your nose, which can detect hundreds of chemicals. For instance, bananas have a flavor that is clearly more complex than sweet, salty, bitter, umami, and sour. Turns out it's the isoamyl acetate in the banana stimulating your nose that contributes to the flavor of bananas. Your olfactory receptors can pick up on hundreds of chemicals. Smelling is half of flavor. (Incidentally, this is why flavors are muted when you have a cold and your nose is clogged up.) And for the record, chemists *do* use these aroma compounds to mix different flavors together.", "topk_rank": 0 }, { "id": "corpus-26483", "score": 0.7137733101844788, "text": "I ain’t no scientist but here is my two cents... Fruit is designed to ferment (rot) as part of its ability to seed. When fruit falls from a tree (or is picked) the fruit starts to ferment which releases natural sugars making it sweet and juicy - eventually you’ll see the pips, seeds or stones becoming easier to remove like in the case of a peach or nectarine - hard to remove when not ripe, easy to remove when ripe. It’s also beneficial for fruit to tase good because then animals will eat it, not digest the seeds and poop them out miles away from the parent tree/bush. It all comes down to spreading your seed, having the juiciest peach and poop. Story of my life.", "topk_rank": 1 }, { "id": "corpus-51829", "score": 0.7135871648788452, "text": "The type of grapes they use have just the right amount of sugars and tannins and such. And it's definitely not all grapes. But it's not exclusive. There are plenty of fruit wines made from other fruits. Usually they use grapes too, for the reason mention above, but sometimes there are no grapes. They probably have to add sugar though.. And I don't know if this part of the reason too, but grapes grow well in areas where other fruits don't. Dry conditions actually make for sweeter wine.", "topk_rank": 2 }, { "id": "corpus-166008", "score": 0.7115361094474792, "text": "How they're made? Chemical reactions which are company secrets (thought I'm sure you could find some online). The better question is how they work. Artificial flavors aren't derived directly from what they are meant to resemble. Instead, something like the juice of a pineapple is analyzed. The chemical composition of this is analyzed and found out. Our tongue, when it tastes food, has receptors on it which react with different chemicals which then send a message to our brain which trigger a memory. The memory is one we usually relate to a food. So if a tongue reacts with a banana, the brain then associates those chemical signals with a banana. All the companies then have to do in order to replicate this is reproduce these chemical signals by making a chemical which triggers them.", "topk_rank": 3 }, { "id": "corpus-191797", "score": 0.711029589176178, "text": "Maybe a bit late to answer, but I wanted to chime in with a different perspective: there is also a reason why *fruit* are rarely blue. It is because most fruit are acidic. I don’t know the exact biochemical link, but acidic things are more often redder and alkaline things are more often bluer.", "topk_rank": 4 }, { "id": "corpus-24839", "score": 0.7099624872207642, "text": "It's probably due to how ripe the fruit is. The longer a fruit stays attached the plant, the larger it will get. As it gets older/riper, the fruit changes its sugar/acid composition, to more sugar less acid, making it sweeter. The small less ripe ones have less sugar and more acid, making them sour.", "topk_rank": 5 }, { "id": "corpus-232994", "score": 0.7098515629768372, "text": "Bananas. My biology professor told us this in class, so It is most likely true. Bananas in the entire world are genetically identicaly. They all come from one crop, that's why they all taste the same. But in fact there different kinds of bananas in the world, and each tastes different (there are hundreds). Now, before the 80s all the crops where from one species of banana, let's call it X. So all bananas in the world tasted like X. But a disease hit crop X and it was bad, so they had to change the crop, so they choose crop Y(todays bananas) so that's how all the bananas in the world became the same new taste. Now if you want to know how old bananas taste like, check out those small cheap candy that are banana flavored but taste nothing like banana, that's because they taste like X not Y.", "topk_rank": 6 }, { "id": "corpus-25734", "score": 0.7083607316017151, "text": "Many of the more favourable taste sensations we get from food are caused by a mix and blend of various flavour-carrying chemicals. Some tone down others, others cause mild flavours that are there to be stronger. For example, the best chefs sampling a dish might add a little lime juice to their stirfry because it needs some \"acid\" to balance some of the other too-strong flavours that are there, and of course soups taste much better when salted to the right level. One of those flavour contributors is sugar. Take it away, and the taste of the end-product could considerably change, even if you don't detect a noticeable \"sweet\" taste in the product when you taste it. Another point is that sugar caramelizes when it's cooked, so things like barbecue sauces become sticky and tacky and form a dry-ish coating when cooked onto food.", "topk_rank": 7 }, { "id": "corpus-21968", "score": 0.7080517411231995, "text": "for starters sugar is a carb. with that said, ignoring artificial sweeteners, there are only 2 \"sugars\" fructose and glucose. The same molecules are in fruits as is in that big bag of granulated sugar. different ratios of fructose and glucose, but even then, they all generally hover around 50/50. Both sugars are generally the same thing to your body. they process a bit differently, but its not important to a healthy person. So yes, they are the same sugar. With that said, fruits tend to have some fiber, which slows their digestion, they also have some vitamins and a bunch of water. So by volume, much less sugar. sweets tend to either be candy sugar, or mixed up with flour for some more carb goodness, highly concentrated, no vitamins, and surrounded by more things that arent beneficial. as always, the ultimate answer is \"moderation\".", "topk_rank": 8 }, { "id": "corpus-54823", "score": 0.7071053385734558, "text": "Naturally occurring sweet items such as fruits and berries, have a semi sweet smell to them to help lure animals towards them, consume them, and then proceed to spread their seeds and make new plants. Part of what makes them enjoyable is the taste. This association of sweet smell = sweet taste from an evolutionary standpoint helps to ensure the survival of the species. In things such as soaps and perfumes, that may or may not contain the same chemicals/plant based ingredients, there are other chemicals that have tastes that far outweigh that of the 'sweet scent' on your tongue. Usually these are chemicals meant to make the smells and product last a long time. In products that don't contain the plant/sweet item derivative, they chemically reproduce something that is close to the original to pass it off as the same or similar smell. These chemical reproductions of scents generally won't taste good unless taste is also a factor considered in the development process.", "topk_rank": 9 }, { "id": "corpus-160470", "score": 0.7070797085762024, "text": "They can't make *every* flavor. Since they're creating them artificially, some flavors will be less accurate than others. IMO, lime and watermelon are two other natural flavors that they can't properly reproduce.", "topk_rank": 10 }, { "id": "corpus-41298", "score": 0.7069776654243469, "text": "In the specific case of banana vs. banana-flavored things, it's because the flavoring is based on a different species. Modern bananas are Cavendish, versus the Gros Michel which is no longer around in great quantities.", "topk_rank": 11 }, { "id": "corpus-48799", "score": 0.70634526014328, "text": "The other juices certainly exist, and are (for example) more common in Mexican markets than in American ones. The less common ones tend to be extremely sweet, very thick/pulpy, made of relatively costly/uncommon fruits, or made of fruits that are only in season a short time and thus rarely available in the surplus quantities needed for industrial production of juice.", "topk_rank": 12 }, { "id": "corpus-111622", "score": 0.7059949040412903, "text": "The fruit break down the starch is it to sugar so it taste sweater. Starch and other carbohydrate is food is long chains of sugar molecules connected together. Even cellulose tat wood is made of is long chains of sugar.", "topk_rank": 13 }, { "id": "corpus-101628", "score": 0.7058821320533752, "text": "sweet and taste are not the same things. sugar have own taste, aspartame have different taste, high-fructose corn syrup have different taste. everything have own taste.", "topk_rank": 14 }, { "id": "corpus-39902", "score": 0.705862820148468, "text": "As fruit ripens, enzymes (chemicals) in them break down the starches into sugars. Sugars taste sweeter than starches.", "topk_rank": 15 }, { "id": "corpus-283613", "score": 0.7052351236343384, "text": "Not with the fruit we eat, since most of it is cloned. For example every single banana you have ever eaten is genetically identical. Same goes for some other fruits too. In the best case you could probably trace a fruit to a region or a single orchard, but beyond that all the plants are propagated by cuttings (cloning) so you could never tell which exact plant it came from.", "topk_rank": 16 }, { "id": "corpus-55143", "score": 0.7048216462135315, "text": "It doesn't know. But the ones that didn't taste good lost whatever benefit comes out of getting eaten, right? The ones with the positive traits survived, the other plants died out. If having your fruits eaten helps in survival, then look at it this way: its not that plants knew what tastes good. Its that the plants that DIDNT taste good died out.", "topk_rank": 17 }, { "id": "corpus-54092", "score": 0.7037370204925537, "text": "It's an incredibly complex reason, actually. In order to break it down, I'm going to put in bullets points, and possibly make a power point. Alright, here we go. *Sugar tastes good, and enhances lots of flavors. Eating sugar makes you want more of it. *Actually, that's it. That's the reason. The explanation was way easier than the build up.", "topk_rank": 18 }, { "id": "corpus-85759", "score": 0.7034790515899658, "text": "Honey isn't just sugar, it's a complex mixture of over 180 different chemical compounds, some of which are derived from the bees themselves, but some of them are derived from the nectar source. Different plant species create nectar with different chemical profiles, so it makes sense that honey from different plants will have different taste profiles.", "topk_rank": 19 } ]

[ { "id": "corpus-325433", "score": 0.7647314667701721, "text": "Basically it's much, much, much more likely for a nebula to have some net angular moment than not. To have no rotation the motion of all the particles that make it up would have to be so carefully balanced and there could be no perturbations from other systems. Basically it just never happens." } ]

[ { "id": "corpus-114450", "score": 0.726320207118988, "text": "It's funny because this question was actually asked to me by my 10-years old. So: the pre-requisite is \"planet formation\" Is it clear to you how planetary systems form? Stuff and dust and gass that \"fall\" towards its gravity center, creating a vortex and some \"lumps\" of condensed matter. The bigger lump is usually in the center (that's the star), smaller lump turn around (the planets) Ok? this said, it's really simple: if a planet is REALLY large, the pressure at its center is enough to start fusion reactions, and the planet actually becomes a start. So, the explanation is: if sometimes happens that some of the \"smaller\" lumps are large enough to become stars. To put things into perspective, if Jupiter was about 50 times heavier, that would be enough for it to become a star", "topk_rank": 0 }, { "id": "corpus-62143", "score": 0.7259831428527832, "text": "A lot of planets are thought to have formed from a Protoplanetary disk which underwent gravitational collapse to form the planets (and Pluto) that we all know and love today. The asteroid belt is also thought to have formed this way but was either unable to collapse due to gravitational stability or it is the result of 2 bodies colliding. The bodies that are not in the same plane are (probably) from a body falling into our solar system from elsewhere or were swung out into an odd orbit during collapse.", "topk_rank": 1 }, { "id": "corpus-236351", "score": 0.7258836030960083, "text": "Kuiper Belt objects \"condensed\" gravitationally and then chemically reacted (creating water and whatnot) basically at the same time than every thing else in the solar system inside of the Solar Nebulae. Gravity does not need temperature to bring objects (like dust of gas) together.", "topk_rank": 2 }, { "id": "corpus-314564", "score": 0.7256738543510437, "text": "Things like disk galaxies and the solar system get their disk shape from friction and/or frequent collisions, with objects or particles losing losing their momentum perpendicular to disk by colliding with others. In the Oort cloud, there is no real friction and barely any collisions, so there's no way for it to become more disk-like.", "topk_rank": 3 }, { "id": "corpus-298119", "score": 0.7255749106407166, "text": "If you are fine with bound rotation (they appear in the same place in the sky all the time), then the orbital dynamics discussed by /u/dukesdj are not an issue, and you just have to keep them outside the Roche limit for liquid bodies - a few times the radius. At a (center to center) separation of 5 times the radius the planet occupies about 3% of the visible sky. It would be ~30% larger than Jupiter in [this video](_URL_0_) - very impressive. Without bound rotation, tidal gravity will change the orbits in some way (depending on the rotation) - the system won't be stable over long timescales.", "topk_rank": 4 }, { "id": "corpus-324920", "score": 0.7254126071929932, "text": "Well, our planets formed from the same gas/debris cloud that our sun did, itself a remnant of older stars which had gone super nova. Not all elements are created in [active] stars though, as stars through fusion can only create the elements up to Iron... everything else came from supernovae.", "topk_rank": 5 }, { "id": "corpus-322673", "score": 0.7253748774528503, "text": "Because of conservation of angular momentum. Objects form from smaller stuff colliding and sticking together. If you have two or more objects, unless they collide head on, the final object has angular momentum and will be spinning. It's incredibly unlikely that anything in space was formed from objects colliding head on with each other.", "topk_rank": 6 }, { "id": "corpus-324891", "score": 0.7250863313674927, "text": "I am not sure what \"spatial\" means in this context but, I'll answer why the planets in our solar system are in a plane. The sun and all the planets were formed from a big ball of gas (the proto-solar nebula), that slowly collapsed in on itself due to its own gravity. At some point, the fact that the gas was slowly spinning generated a force that was comparable to the gravitational collapse, and the system formed more into a plate-like shape. Most of the gas stilled flowed toward toward the center, and formed the early sun. Some of the rest of it, especially the sooty particles we call astrophysical dust, agglomerated into the planets. The planets retained the motion of the gas and dust they were born from, and thus all orbit in the same plane, which has the same sense of rotation as the sun itself. I am not up on all the recent results from Kepler and other planet finding missions, but I do believe that not all systems have all the planets in a relatively flat plane, though most do.", "topk_rank": 7 }, { "id": "corpus-324195", "score": 0.7246454954147339, "text": "Gas clouds usually don't have enough pull to converge into planets on their own, if they aren't extremely large or dense. And as tendrils, their parts are already likely to be moving apart from each other in one of the three dimensions. So it will usually only happen when the tendrils are extremely dense, extremely massive, or get pushed together by an outside disturbance, like the blast of a supernova. Edit: The first two cases would be likely to leave stars nearby. Only with some disturbance I'd expect 'free' planets to develop. And there's probably quite a few sub-brown dwarf gas giants between the stars.", "topk_rank": 8 }, { "id": "corpus-310888", "score": 0.7233918309211731, "text": "I worked with a professor of Astrophysics for a little while and we were working on planetary formation within gas clouds surrounding freshly formed stars. The densities in these clouds can, it seems, reach the level of an atmosphere. Meaning, theoretically, if the gases were right, one could breathe, unassisted. Of course, I don't know of any evidence, but as the science fiction writers referenced here have written, it's definitely not out of the realms of reality.", "topk_rank": 9 }, { "id": "corpus-182658", "score": 0.7230515480041504, "text": "Not the big bang, at least certainly not directly. It is something known as the conservation of angular momentum. Basically when particles clump together they don't join perfectly instead they hit each other off-centre which causes them to rotate this initial rotation is enhanced by each new particle joining. However in the case of the Earth the formation is from a proto planetary disk ejected from the Sun when it was forming - _URL_0_", "topk_rank": 10 }, { "id": "corpus-835368", "score": 0.7230308055877686, "text": "All pictures show the planets on the same level or plane. Is that true or is it simplified for the general public? Or do the planets circle the sun with each planets orbit following it's own path?\n\nIf they do orbit the sun on the same level is that because the sun causes them to rotate along a certain axis? \n\nSorry if it's been explained before but I couldn't find the answer to my actual question(s). Thanks in advance", "topk_rank": 11 }, { "id": "corpus-287774", "score": 0.7228223085403442, "text": "Not really, for a couple reasons. One, the vast, vast majority of the material in our solar system is in the sun in the form of hydrogen. That hydrogen was mostly never inside a star, though perhaps some was in a star but never fused. So most of the material in our solar system was never in a star. The heavier elements, like those making up Earth and other rocky planets, were created by heavy stars it's true, but not one single one. Instead, many stars impregnate the interstellar medium with heavier elements. Then a local cloud came together from that medium and formed our solar system. However, sometimes a very close supernova can \"trigger\" a cloud to collapse and form a star, and it's thought there may have been a single local star which went nova and triggered the birth of ours. While very little of our solar system is composed of matter from that star, there are some trace elements which came from that supernova.", "topk_rank": 12 }, { "id": "corpus-81549", "score": 0.7226681709289551, "text": "If you're wondering why all of the planets lie on the same *orbital plane*, it's because the planets were formed from orbiting debris, and that angular velocity (ie the spin) was preserved as the debris flattened out into a disc due to the effect of gravity.", "topk_rank": 13 }, { "id": "corpus-1333566", "score": 0.7226518988609314, "text": "I want there to be solar systems with two stars orbiting each other, and a single stationary, rotating, world at their lagrangian point.\n\nSomeone please tell me that this is accounted for and does exist in NMS.", "topk_rank": 14 }, { "id": "corpus-834905", "score": 0.7224084138870239, "text": "I admit that I'm not up on gravitational physics but I am wondering what actually holds planets together. Is it our molten core spinning so fast that creates enough gravity momentum to keep everything together? What keeps everything in equilibreum?", "topk_rank": 15 }, { "id": "corpus-322099", "score": 0.7221773266792297, "text": "Assume that at one point they were much more of a cloud. The particles were all moving in fairly random directions in their orbit around Saturn. When two collide, they will lose much of the component of their directions that opposed each other. After many, many collisions, a preferred direction starts to be obvious. As the flattened disk starts to form, any particles moving \"vertically\" with respect to the disk have to pass through the disk two times on every orbit, thus with a high probability of further collision. Basically, a flattish disk of particles is the equilibrium state for a cloud of orbiting particles, and any cloud-like behavior tends to the disk more and more as the disk becomes prominent.", "topk_rank": 16 }, { "id": "corpus-321200", "score": 0.7219701409339905, "text": "The rings will end up in the same disk because collisions occurred when they weren't. The system tends towards stability in that respect. Another way to put it is that the whole system has a particular angular momentum, and the parts of the system will reflect that with time. It's the same reason that the bulk of the material in our solar system is in the same plane, and likewise, the majority of the mass of our galaxy is all in roughly the same plane.", "topk_rank": 17 }, { "id": "corpus-323906", "score": 0.721167266368866, "text": "Everything spins. Essentially because everything is not *perfectly* uniform, as it falls together, it doesn't fall straight \"toward\" the center. It falls, but misses passing through the center and shoots off into an orbit. This is true of stuff falling into place around the sun (forming planetary orbits) and stuff falling into a planet, forming it (forming planetary rotation). This is also why *more or less* everything orbits in the same plane (a practically flat solar system), in the same direction, and generally, rotates in the same direction. (notable exceptions include Venus, which nearly doesn't rotate at all, and in fact does so \"backwards\" with a \"day\" longer than its year; and Uranus, which, for some reason, is tipped such that its pole lies almost in the same plane as its orbit)", "topk_rank": 18 }, { "id": "corpus-79177", "score": 0.7211280465126038, "text": "As the sun formed, some of the material flung off. Some of it was ejected far out into space, some was pulled back in, but some was flung at just the right velocity to orbit the sun. Through electromagnetic forces at first and then gravity, this stuff in orbit started pulling together into clumps. As these clumps orbited, they picked up more matter, increasing their gravity and thus pulling in even more matter in their orbital path. All sorts of chaos likely ensued as different clumps bumped into each other or had enough gravitational influence to fling them around. But over billions of years, things eventually settled into a stable configuration as the planets we see today.", "topk_rank": 19 } ]

[ { "id": "corpus-325434", "score": 0.6357918977737427, "text": "Yes, the chlorophyll breaks down over the course of a day or two, causing it to lose its pigment. The grass will not spend energy making new chlorophyll until it has a means of transportating it and other nutrients to throughout the leaves, which requires a certain amount of water." } ]

[ { "id": "corpus-1707002", "score": 0.6039662957191467, "text": "I have had this heartleaf philodendron for about 6 months now (it was grown from a cutting) and recently it appears to have taken a turn for the worse. Pictures Some background: it's indoors with access to sunlight from the window. I keep my room at about 70 degrees and water the plant a couple times a week. I keep the philodendron exclusively indoors and live in Nebraska. Thanks for your help!", "topk_rank": 0 }, { "id": "corpus-159742", "score": 0.6039354801177979, "text": "Plants derive most of their mass from the air! CO2 (carbon dioxide) is converted into fuel and mass for the plant via photosynthesis. From their roots, plants acquire water and nutrients. Water is transitory in the ground, and thus the large amount of water used by a tree wouldn't cause a depression. And the nutrients acquired by the plant are in very minute quantities. So, in summary, plants get their mass from the air! Cool huh!", "topk_rank": 1 }, { "id": "corpus-281801", "score": 0.6039152145385742, "text": "Of the three functional groups you mentioned, only carboxylic acids can be dehydrated, since aldehydes and ketones do not have -OH groups, only =O. Aldehydes and ketones can take part in condensation reactions that produce water, but are not themselves dehydrated. Carboxylic acids can be dehydrated by forming compounds called acid anhydrides. Secondary and tertiary alcohols can also be dehydrated just like primary ones.", "topk_rank": 2 }, { "id": "corpus-177915", "score": 0.6038399934768677, "text": "A combination of capillary action and suction. The leaves are still alive, they are drawing the moisture and nutrients up from the base of the tree and expelling some of the water through tiny pores in the cells of the leaves. Or return it back down to what would have been the roots. _URL_0_ So dipping a cut tree or flower will suck up some water and prevent it from drying out.", "topk_rank": 3 }, { "id": "corpus-555578", "score": 0.6038053035736084, "text": "So my lawn looks great in early Spring, and then a month or so into Spring I start to notice areas where it gets yellow/brown'ish and stays mostly like this throughout the Summer. I can't figure out whether it's too much/too little water (doubt it's either, since it's same spots every year and I've tried watering). Fungus, but again, would this stick around year after year? Some of this grass is from sod, while the rest is from seed, if that makes a difference. The worst pic I think is from too much weed n' feed, maybe burnt some grass but otherwise I can't tell why the other areas looks like this year after year.\n\n&amp;#x200B;\n\nEdit: living in zone 5B\n\n&amp;#x200B;\n\nHere are some photos: ", "topk_rank": 4 }, { "id": "corpus-1707352", "score": 0.6037716865539551, "text": "I've had a plague of root rot in my flat which ended my beloved Philodendron and also two new sweet-heart plants, so I chopped them up and put them in water hoping to try again one day - but theyre so happy in the water I'm really reluctant to pot them again. \nCan they just live indefinitely in water? Is there a downside to have loads of plants in water?", "topk_rank": 5 }, { "id": "corpus-311903", "score": 0.6037706136703491, "text": "The plant stops producing chlorophyll. The other pigments in the plant are always there (they are called accessory pigments and they help to absorb more light for photosynthesis), and without the overwhelming green of the chlorophyll they become easier to see.", "topk_rank": 6 }, { "id": "corpus-1706576", "score": 0.6037389636039734, "text": "I found a pot to put my sprout in that I thought had good drainage but I was wrong. The holes didn't go all the way through the pot. It had dirt in it already so I didn't notice. \nI went out and watered the plant and didn't think to check the forecast, it rained really hard later that day. When I went and checked it today there was like an inch of water covering the soil and the plant was laying sideways completely waterlogged and floppy. The plant is maybe four inches tall with like 4-6 leaves so it's still pretty young. I stabbed a bunch of holes in the bottom of the pot and poured out the water sitting on the top and set it in direct sunlight with the leaves propped up facing the sun. \nThe soil is still very wet. It's in a big pot so it may take a while to dry out. Is there any chance of saving the plant? It was like that for probably just under a day. \nI'm not looking to harvest much or anything from it. Just want it as a plant like any other flower.", "topk_rank": 7 }, { "id": "corpus-646473", "score": 0.6036977767944336, "text": "some said because it is hygroscopic, absorb moisture from atmosphere. Some said it reacts with carbon dioxide readily . Some said it can form water of crystallisation , etc . But when I googled them , none of them are based on concrete evidence. Can anyone answer this question. A source provided will be much appreciated . Thanks", "topk_rank": 8 }, { "id": "corpus-1706750", "score": 0.6036653518676758, "text": "Is a plant ruined if it's grown tall from reaching for light? If it has a few leaves but has grown more tall than it's supposed to in about 2 weeks", "topk_rank": 9 }, { "id": "corpus-157778", "score": 0.6035950183868408, "text": "Besides your being torturously dehydrated which can have severe impacts on your reasoning and perception, mirages can actually be the result of some pretty cool physics. When light from the sky comes it an angle towards the hot sand or asphalt, it will actually bend away from the ground back up towards your eye. Thus if its very hot and you look out at the horizon you may see some blue just beneath it. To a desperate person this looks like a pool but its really just the sky. If you're wondering how the light bends, the way I think about it is you're offroading in a car. If the drivers side is in mud and the passengers side is on a dryer surface, then the wheel is gonna naturally pull towards the mud. In the same way light beams get pulled towards the slower medium which in the case is the air further away from the asphalt.", "topk_rank": 10 }, { "id": "corpus-2452974", "score": 0.6035930514335632, "text": "hi, I have a mango tree in my kitchen, which is maybe two years old and has only grown inside its whole life. The last few days , the leaves have started to lose color and lose strength. It is watered very often and almost never to much, yet it starts drying out. This has never happened before. Btw I live in sweden, so maybe the winter makes it a little weak?\n\n&amp;#x200B;\n\n", "topk_rank": 11 }, { "id": "corpus-295417", "score": 0.6034569144248962, "text": "The two most significant issues with severe dehydration are the loss of perfusion volume as well as the electrolyte abnormalities that develop. If someone is hypovolemic enough, they will not be able to maintain an adequate blood pressure to supply oxygen to their organs, which results in multi-organ failure (in particular, the heart, brain, kidneys, and liver are particularly vulnerable). In addition, changes in electrolyte concentrations in the blood (most typically sodium or potassium) can result in comas or seizures as well as cardiac arrhythmias.", "topk_rank": 12 }, { "id": "corpus-2099845", "score": 0.6034170985221863, "text": "I jack off into a glove then hide it from family. Once I’m ready to clean my nasty jizz-filled glove then dry it outside, I always notice that my cum turned yellow. Why exactly is that? Is it like how an apple turns yellow when dropped on the floor or something? I need answers!", "topk_rank": 13 }, { "id": "corpus-12423", "score": 0.6033875942230225, "text": "Paper and most clothing is made of long chains of molecules that will attract and loosely bind water. When they get wet the structure of the molecules that make up the paper or cloth changes slightly allowing more light to pass.", "topk_rank": 14 }, { "id": "corpus-284192", "score": 0.603312075138092, "text": "Generally oceanic mammals get their fresh water needs from their food. If they don't eat they also dehydrate.", "topk_rank": 15 }, { "id": "corpus-1708422", "score": 0.6032586097717285, "text": "So I bought my jade a couple weeks ago. The soil was really dry, I waited a couple days then I watered it. Then I kept it outside in the sun. After two days (today), the some leaves and stems turned really pink. As I touched them, they were cold, thin and really bendy. I moved them back indoors next to the window. What do you think the problem is?", "topk_rank": 16 }, { "id": "corpus-1708148", "score": 0.6032406687736511, "text": "Hey everyone!\n\nI'm only an amateur grower, 2nd year actually. My first year was plagued by aphids, but was still successful! This year however, I'm stumped about problem(s) with my Paper Lantern Habanero plant.\n\n\n\nSome of the leaves near the top began to curl up, I gave it some time guesssing it was due to overwatering but no change. The leaves were soft to the touch instead of firm. (First pic)\n\nMajority of the leaves all have these little white dots undearneath, they don't fall off with scraping. A google check said it may be down to overwatering, all of my chilling plants have this to an extent.\n\nThe bigger leaves near the bottom had started to get black dots on them, with some bigger white ones.\n\nCould anyone confirm what is the cause of the wilting, black dots and the smaller white lumps under my leaves? The other plants are healthy and are growing lots of chillis! Even this has chillis growing on it.\n\nAppreciate any responses.", "topk_rank": 17 }, { "id": "corpus-1707023", "score": 0.6032149791717529, "text": "So, I am growing a few variety of melons (Charleston grey watermelon, Strawberry watermelon, and Petit Gris de Renne melon) and besides the fact that I made the mistake of starting them indoors (we just bought a house and just got the keys a couple days ago, so I did not have access to the yard in order to prepare my plot, but am planning to ASAP), everything was going great! \n\n&amp;#x200B;\n\nI am a first time gardener and I REALLY want to plant this year, so even though I did not have my yard quite yet, I went ahead and started them indoors so I could get them going. I was pretty surprised when they exploded and were huge! Regardless though, they seemed to be growing nicely and put out their first true leaves, but then I checked them today to find some of them have shrunk up and turned mottled.\n\n&amp;#x200B;\n\n I have googled a bunch and can not seem to figure out what is going on. Only the melons (all 3 varieties) were affected (though only some, not all. I have separated out the affected ones in case it is transmittable to the others). I have some pumpkins growing as well, and they are completely fine, as well as the various tomatoes and flowers. I'm really not sure what the issue is. Perhaps it is overwatering? I watered them a day or two ago (last watering before this was a week before) and maybe it gave them too much? I don't know. \n\n&amp;#x200B;\n\nI would REALLY appreciate it if you guys could help me out and at the very least, save the others! Thank you so much! Photo is of a normal and an affected Petit Gris de Renne melons. Additional photo in the comments of another melon where the first true leaf has shrunk.\n\n", "topk_rank": 18 }, { "id": "corpus-306318", "score": 0.6031643152236938, "text": "Leaves are colored by molecules called pigments. The pigment that causes leaves to be green is **chlorophyll**. Chlorophyll is important for plants to make food using sunlight. During Spring and Summer when there is plenty of sunlight, plants produce a lot of chlorophyll. In Autumn, as sunlight decreases and temperatures cool, some plants stop producing chlorophyll. Instead, those plants break down their chlorophyll into smaller molecules, and transfer them out of the leaves before the leaves fall. This molecules are stored elsewhere in the plant until Spring. Then, they will use this stored material to rebuild their chlorophyll more easily. Once the plants have broken down the green chlorophyll, other pigments in the leaves are revealed, e.g. carotenoids which are yellow and orange. Anthocyanins are other plant pigments that are only produced in the fall. These pigments cause red, pink, or purple colors.", "topk_rank": 19 } ]