title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"When investors say that stocks outperform things like bonds in the long run (as they have over the past 100 years), couldn't that outperformance just be an artifact of that particular 100 year timeline?"
] | [
false
] | When looking at for investments, one can clearly see the stellar performance of equities over the long haul. That being said, we know that we can center in on certain 20-25 year time spans throughout that century where the return characteristics look drastically different. If this is the case, then couldn't the entire 100 year period demonstrating the attractive returns for stocks be an aberration over hundreds or thousands of years, especially considering how since pre-history? And how could we hope to know? Is there a statistical/probabilistic way to be understand whether our "long-run" returns are in fact indicative of some sort of deep principle regarding average returns in a market economy? | [
"In order to answer this question, we would need to first answer one bigger question that is the topic of many books: Is the stock market random? If the answer is yes, then one can answer your question in the manner that you have asked. We need only find the standard deviation and calculate the chances that over 10... | [
"Piketty does an analysis of historic investments and returns in his book, and claims the uber-wealthy do most of their investment in BONDS and RENTABLE REAL ESTATE, both of which return 3-4% per annum. Equities \"should\" be pegged to growth in the economy, which Piketty shows pretty clearly averages around 1%. Th... | [
"Stocks are basically ownership of a company.",
"Bonds are basically loans to a company.",
"If loans to a company were more profitable than ownership of a company (in general), most people would not want to own a company anymore. ",
"Ownership of a company ",
" on average more profitable than \"just\" lendi... |
[
"Are solar panels worth buying now?"
] | [
false
] | null | [
"Not a science question."
] | [
"How is it not a technology question? Basically asking if the technology of solar panels is improving so quickly that it worth waiting a year or two to buy them because they will get better "
] | [
"We don't offer advice here."
] |
[
"Is there any natural evidence of the higher dimensions or have we totally made the concept up?"
] | [
false
] | It makes sense (though I can barely comprehend it) and was wondering if there has been any real sitings of fourth dimensional objects or activity. I was thinking maybe in quantum level since I heard the physics there doesn't behave normally? | [
"I think in context the question is referring to spatial dimensions."
] | [
"Is there any natural evidence of higher dimensions or have we totally made the concept up?",
"I think the answer to your question is no on both counts. There is no explicit evidence of extra dimensions, but it is also not a totally arbitrary suggestion, as there are phenomena that are nicely explained by extra ... | [
"It is possible to ",
"predict the implications of extra dimensions and then look for signs of those implications",
". However, thus far, there have been no positive results and the universe is three dimensional as far as we know."
] |
[
"Why is the shape of the universe assumed to be a 3-manifold?"
] | [
false
] | From the Wikipedia page on "shape of the universe": In practice, more formally, the debate seeks a 3-manifold that corresponds to the spatial section (in comoving coordinates) of the 4-dimensional space-time of the universe. Why? Wouldn't a plain 3 dimensional shape represent the spatial section of a 4-dimensional universe which has 1 time dimension? A would correspond to the entire 4-dimensional spacetime of the universe, There are 3 spatial dimensions to the universe, not 4. A 3-sphere models 4 dimensions. | [
"Because ",
"time doesn't have a Euclidean coupling to space dimensions",
".",
"Edit: thinking about this more, I may have misunderstood your question, so please feel free to correct me."
] | [
"We aren't using a 3-sphere to model the spatial part. To our best understanding, the spatial subspace of space-time is an infinite Euclidean plane."
] | [
"Then what are we using the 3-sphere to model if not the spatial section of the universe as it said in the quote from the Wiki article?",
"Because a 3-sphere is a ",
" dimensional object with positive curvature, which makes it a good model for a universe that has positive spatial curvature.",
"Why is it an in... |
[
"Would a sample of cesium decay slower if it were traveling near light speed? Would it stop decaying if it were traveling exactly light speed?"
] | [
false
] | If so what properties are involved? Did einstein figure this out? | [
"If you observe it from an outside frame of reference, yes, it would appear to decay more slowly. If your frame of reference is within the same system as your cesium sample, it would appear to decay at the same rate as ever. ",
"Time dilation applies to everything."
] | [
"It would be a fresh, non-decayed sample, because less time would have passed in the system that our cesium has been moving in than to other, slower moving observers."
] | [
"The cesium used in atomic clocks is specifically just the cesium-133 isotope, which is stable and doesn't decay."
] |
[
"Question about methylation."
] | [
false
] | When referring to methylation in biology are we talking about dna methylation only. I have noticed links between neuro diseases and methylation and also methylation tests. Are methylation test diagnostically useful? and with regard to the illumina test would it be possible to categorically say or not if a gene was silenced? Also whalt sort of sample would be supplied. I was imagining that each cell would likely have a different methylation pattern or fingerprint. | [
"When referring to methylation in biology are we talking about dna methylation only.",
"DNA methylation is the most well known epigenetic modification. In addition, histones can be methylated or have a large number of other modifications like acetylation, phosphorylation, ubiquitilation and others. ",
"Epigenet... | [
"Thanks for your help. How straightforward is it to know if a gene is being effected by examining a methylation array?"
] | [
"Bioinformatically, quite straight-forward. We can use tools like the ",
"genome browser",
" to display histone modification tracks. However, ",
" genes have their transcription effected in a sense by histone modifications. Nucleosomes, histones and the covalent modifications that appear on the histone tails ... |
[
"What happens to bugs (e.g. mosquitoes) when they bite a human and the human has natural insecticides in their system (caffeine, nicotine, cocaine, psilocybin) or even alcohol... do they die or get high?"
] | [
false
] | null | [
"According to ",
"this",
" article, concentrated doses of stimulants such as caffeine caused a distortion in mosquito behavior, followed by death.....so both.",
"I wouldn't think the levels of these stimulants could be high enough in the bloodstream for it to have a lethal effect on mosquitoes, though.",
"A... | [
"In fact, there is a drug that is already used in many parts of Africa to treat river blindness and elephantiasis that has been shown to kill mosquitoes that bite humans with this drug in their bloodstreams. Obviously this has implications for helping reduce malaria. ",
"Source"
] | [
"I really wish I could answer this, because I'd love to give those little mother fuckers what they have coming to them."
] |
[
"Does every part of us become replaced over time?"
] | [
false
] | null | [
"Everything, except stable cells that don't actively divide: nerve, muscle, ligaments, cartilage undergo constant division. The cells with the highest turn over rate are our skin cells, and the lining of our gastrointestinal tract."
] | [
"As far as I know the cells in your brain don’t regenerate. Neural pathways are one of the few “one and done” cells and cell structures in our body, and that’s why it’s difficult to come back from brain injury, and why drugs and addictive chemicals are terrible for your brain. But it’s been a minute since I’ve take... | [
"except stable cells that don't actively divide",
"Even they replace a good fraction of their molecules over time - I'm not sure if there are any that don't get replaced at all."
] |
[
"what is the statistical distribution of the numbers from 0 to 9 in the decimal places of pi (or any other irrational number)?"
] | [
false
] | E. g. in 3.1415926535 there are 10 decimal places, 2 of which are the number "1", ergo it appears 20 % of the time. (My intuition would be, that it converges to 10 % each.) | [
"We don't know, but it's conjectured and considered very likely that the decimal digits are distributed evenly. This is what is meant by a ",
"‘normal’ number",
".",
" Almost all numbers are normal, but it is surprisingly hard to prove that a specific number is normal.",
"This is not true for all irrational... | [
"very likely that the decimal digits are distributed evenly.",
"...",
"It also requires that all pairs of digits occur equally often (1%),",
"I realised I've never seen this in practice, so if anyone is interested: ",
"I wrote a short piece of code to calculate the occurances of each digit and each pair of ... | [
"We know that almost every number is normal (in the sense that if you pick a random number between 0 and 1, the odds of it being normal is 1",
"I want to give a rationale (not proof) for this, in case anyone is interested. Consider the set of binary numbers between 0 and 1 with n digits. Let N(n,p) be the number ... |
[
"Why do clouds clump together rather than an even spread as the molecules are free to move?"
] | [
false
] | Is there cloud tension? Is it just London forces? | [
"Anywhere that you see puffy discrete cumulus clouds is an indicator that there was rising warm, moist air. As that air was lofted upwards, it expanded to match the local pressure, cooled, and some of the moisture condensed out to form a cloud.",
"You can't have these rising warm convection cells everywhere. For ... | [
"Clouds are localized because rising air currents are localized.",
"Which, of course, begs the question - why are rising air currents localized?",
"It's been observed for about 100 years that convection in the atmosphere tends to organize in such a way that downdrafts occupy roughly 9-10x as much spatial area a... | [
"I saw a mathematician give a colloquium presentation about this. She built a hierarchy of simple physical models that incorporated different levels of complexity. She found that models below the level incorporating gravity waves had an even spatial distribution between cyclonic and anticyclonic systems, while mo... |
[
"Is this a geometrical rationale for the \"360 degrees to a circle\" convention? (or a coincidence?)"
] | [
false
] | Playing some kids’ geometric puzzle pieces (and then doing some pencil & paper checks), I realized something. It started like this: I can line up a sequence of pentagons and equilateral triangles, end-to-end, and get a cycle (a segmented circle). There are 30 shapes in this cycle (15 pentagon-triangle pairs), and so the perimeter of the cycle is divided then into 30 equal straight segments. You can do something similar with squares and triangles and you get a smaller cycle: 6 square-pentagon pairs, dividing the perimeter into 12 segments. And then you can just build it with triangles - basically you just get a hexagon with six sides. For regular polygons beyond the pentagon, it changes. Hexagons and triangles gets you a straight line (actually, you get a cycle out of these, but it isn't of segments like all the others). Then, you get cycles bending in the opposite direction with 8-, 9-, 12-, 15-, and 24-gons. For those, respectively, the perimeter (now the ‘inner’ boundary of the pattern - see the figure above for an example) is divided into 24, 18, 12, 10, and 8 segments. You can also make cycles with some polygons on their own: triangles, squares, hexagons (three hexagons in sequence make a cycle), and you can do it a couple of ways with octagons (with four or eight). You can also make cycles with some other combinations (e.g. 10( ) pentagon-square pairs). Here’s what I realized: The least common multiple of those numbers (the number of segments to the perimeter of the triangle-polygon circle) is ! (at least, I’m pretty sure of it.. maybe here I have made a mistake). This means that if you lay all those cycles on a common circle, and if you want to subdivide the circle in such a way as to catch the edges of every segment, you need 360 subdivisions. Am I just doing some kind of circular-reasoning numerology here or is this maybe a part of the long-lost rationale for the division of the circle into 360 degrees? The wikipedia article claims it’s not known for certain but seems weighted for a “it’s close to the # of days in the year” explanation, and also nods to the fact that 360 is such a number (can be divided lots and lots of ways - which seems related to what I noticed). Surely I am not the first discoverer of this pattern.. in fact this seems like something that would have been easy for an ancient Mesopotamian to discover.. * * * * For those who don't understand the explanation above (i sympathize): to be clear, this method gets you exactly 360 subdivisions of a circle . , not a tautology, as some people are suggesting.. I thought it was an interesting coincidence because the method relies on constructing circles (or cycles) out of elementary geometrical objects (regular polyhedra). The most common response below is basically what wikipedia says (i.e. common knowledge); 360 is a highly composite number, divisible by the Babylonian 60, and is close to the number of days in the year, so that probably is why the number was originally chosen. But I already recognized these points in my original post.. what I want to know is whether or not this has been noted before or proposed as a possible method for how the B's came up with "360", . Thanks! | [
"It's neither the rationale or a coincidence. :) ",
"The rationale is that 360 is \"highly divisible\". When all you have to work with are integers you tend to divide things up into a number that you can make fractions of very easily. 360 gives a good amount of accuracy with divisibility. ",
"An hour is split i... | [
"This is correct. All of these are examples of “Base 60” or Sexagesimal number systems that were passed down to us from the Babylonians. You can easily divide several important whole numbers into equal parts, which is great before calculators (and still great today, every one of 1/2, 1/3, 1/4, 1/5, 1/6, and 1/10 fr... | [
"And, as I recall, the Sumerians, from whom the Babylonians inherited the system, used base 60 because it originated from the practice of counting the 3 bones in each of 4 fingers using the thumb, resulting in counting to 12 on one hand.",
"If you then use the five fingers of the other hand to count each full set... |
[
"Why are black holes always portrayed in 2-d"
] | [
false
] | To clarify, I mean why is the spiraling matter always depicted as a disc (like ) instead of a sphere? Shouldn't the entire hemispherical face of the star be sucked off and revolve spherically around the hole? Side question. Why are there two pillars perpendicular to the disc? I think it has something to do with radiation emission but it's been a while since I've learned about black holes | [
"The rotation causes the gases to be \"flung\" out into a plane perpendicular to the axis of rotation. It's the same reason why most galaxies are flat. ",
"Basically if you take any fluid and spin it, it will flatten out (in the absense of other forces that can stop it ). In the old days sheets of glass would be ... | [
"Accretion disc"
] | [
"conservation of angular momentum"
] |
[
"Why is the Earth flat?"
] | [
false
] | Looking at this histogram it seems that the vast majority of the landmass lies between 0 and 1000 meters, whereas the majority of the oceans lies below -2000 meters. So if we lowered the ocean level by, say, 1000 meters we would have the majority of the land mass above 1000 meters. Is there a process, which "flattens" the earth, i.e. makes it so that the majority of the land mass is fairly close to ocean level? | [
"robotrebellion has the exactly correct answer, ",
".",
"The majority of the oceans have a low sea floor because oceanic crust is ~7 kilometers thick (roughly), pretty consistently. So it \"floats\" (note: not literally floating) on the mantle (mantle is almost all solid, not liquid) at the same height in most ... | [
"Could ",
"erosion",
" be such a process?"
] | [
"You get more slope for water to erode away (which is a huge player in erosion), you get a larger concentration of rain on the mountain front (which is why you get such massive monsoons against the Himalayas), and at high elevations you encounter [3] glacial buzz-saws that can absolutely shred mountains apart (on l... |
[
"Does gravity work differently underground?"
] | [
false
] | null | [
"The ",
"shell theorem",
" is a useful starting point. For a homogeneous spherical body, gravitational acceleration decreases linearly as you approach the center and it would be zero at the center. The Earth is not a homogeneous body, specifically, its ",
"density varies as a function of depth",
" where the... | [
"Would the 100km above me create a gravitational field oposite to the \"main one\".?",
"The gravity from the surface layers above you is counteracted by the gravity of the surface layers on the other side of the planet.",
"Suppose you're 100 km down. You can conceptually split the planet into two parts. An oute... | [
"But the linear decrease is not a bad approximation if you want a general idea and don't want to wrangle with pages and pages of detailed calculations, all with data uncertainties anyway.",
"I mean, you don’t ",
" to wrangle with all that. Given the helpful context that you’ve just provided then we could just l... |
[
"AskScience AMA Series: Emergency Medicine"
] | [
false
] | [deleted] | [
"Trauma doesn't make you feel that way I find.",
"If anything, it's actually some of the staff at times that can make you feel that way. Some of the things people do to each other, or themselves.",
"I've never felt that way, but some of my worst memories and times are when staff do things, or say things that a... | [
"Just a reminder to all: ",
"medical advice"
] | [
"That's a tough one...",
"Massive burn victims have lost a ton of fluid. The formula for fluid resuscitation in a burn victim means that a 90kg male with burns to 60% BSA will get 21.5L of fluid in the first 24 hours. This can easily double in certain circumstances as well.",
"In terms of sheer blood volume l... |
[
"Has there been a higher peak than Mt. Everest on Earth throughout its history?"
] | [
false
] | Im not thinking a higher mountain in total like the Mauna Kea, but rather from sea level upwards. | [
"This is one of the most asked questions in the Earth Sciences category on this sub, for example, here are a variety of answers to this question (or flavors of this question): ",
"1",
", ",
"2",
", ",
"3",
", ",
"4",
", ",
"5",
", ",
"6",
", ",
"7",
", ",
"8",
", ",
"9",
", ",
... | [
"Oh man, so here we go. The major factors that control mountain height are the planets gravitational field, and the strength of the material you are building with. It also has to do with how buoyant the crust is compared to the mantle. Imagine you're building a sand castle. If you want to make it higher, you use we... | [
"A related question then: Do we have any reason to believe that these factors that limit the height of mountain ranges (and peaks) have differed throughout the Earths history?",
"As a corollary, is there something that could change (or is changing currently) to change these factors in the future?",
"Finally are... |
[
"Why can't we treat viral infections using blood transfusions?"
] | [
false
] | null | [
"Short answer: ",
"we can",
". ",
"Long answer: we can transfuse blood plasma containing antibodies against a virus into an infected individual and it well help them fight off the infection, however they still need to produce their own antibodies and B cells specific to the virus to overcome the infection com... | [
"Thank you for the information, that's very interesting!"
] | [
"Viruses rarely infect just the bloodstream. There are indeed viruses that infect red blood cells such as the parvovirus however once the virus finds its infection site like the neurones for herpes virus it's quite pointless to do a blood transfusion because it won't really affect the virus that much. We can put an... |
[
"If all life on Earth has one common ancestor, then why don't humans (and other life) share some of the best evolved characteristics?"
] | [
false
] | [deleted] | [
"But with characteristics like photosynthesis out there, why did natural selection/evolution choose to leave that out?",
"It didn't. We evolved to eat plants. Photosynthesis needs a lot of surface area to work and we can't carry enough plant material around with us to keep us alive."
] | [
"Some traits evolve after a split with a last common ancestor. For instance, humans and plants share a eukaryotic single celled ancestor that was not photosynthetic. Only after both linages split did the plant lineage develop photosynthetic abilities. So that humans, and all of our ancestors were never photosynthet... | [
"Also, evolution does not neccessarily imply continued improvement."
] |
[
"Is a person standing at sea level on the Equator traveling about the Earth's axis faster than a person standing at sea level at the 49th Parallel? If so, approximately how much faster are they traveling?"
] | [
false
] | null | [
"When we speak of circular motion it is important to remember that there are two type of velocity we can speak of. The first is angular velocity, so how quickly a body moves around that circle. Because both people in your example are fixed on a rotating body, their angular velocity will be identical because they ... | [
"Yep. Assuming the earth is about spherical you just have to look at the difference in the circumferences of the two circles traced out by their paths. The radius of the earth R is 6400km, and the radius of the circle around the 49th parallel r is 6400km*cos(49 degrees) = 6400km * .66 = 4200km. ",
"So, the circum... | [
"I've always heard 'radial velocity' used to mean the component of velocity pointed away from the origin. Maybe this is a difference of disciplines but \"angular velocity\" is more commonly used in physics and astronomy."
] |
[
"What is the difference between EMSA and DNase I footprinting?"
] | [
false
] | null | [
"Holy shit! A question that's right in my wheel-house! Wall of text incoming! ",
"TLDR: They're useful in different scenarios, so pick your poison. ",
"EMSAs (electrophoretic mobility shift assays) and footprinting do kind of measure the same thing. They both let you observe interactions between protein and DNA... | [
"Thanks so much! I'm taking a course in cell bio and this really helped to clarify the differences between the two techniques. "
] | [
"Of course! Let me know if you have any more questions or if something I said was unclear. "
] |
[
"Does every object exert gravity on all other objects within the (visible) universe?"
] | [
false
] | null | [
"Yes, anything with mass exerts a gravitational pull, the more mass, the more gravity."
] | [
"This is a very common question, so I've decided to add it to our AskScienceFAQs:",
"http://www.reddit.com/r/sciencefaqs/comments/135cd1/does_gravity_stretch_forever_is_the_big_bang_like/"
] | [
"Mass is not necessary."
] |
[
"Are covalent bonds always technically polar when two different non-metal elements covalently bond?"
] | [
false
] | I had a clash with my AP Bio teacher. Her test question was "A covalent polar bond is most likely when..." And the choices were: A: when one atom is more electronegative than the other, B: (Incorrect answer) C: (Incorrect answer) D: When there is a bond between two different nonmetal elements. According to Barron's review for AP bio, a polar covalent bond is always the case when two different non metal elements are covalently bonded because they all have different electronegativities. They said "at any case." I asked my teacher about this issue, because based on my understanding, both A and D are correct, but I had to choose one. Barron's never failed me before so I chose D. Aren't both answers technically correct? She told me that Barron's is wrong and that if the difference in electronegativities is small enough, the bond is considered to be nonpolar. Is she right? Or is she making assumptions? I think that Barron's is more detailed and accurate but that's why I'm asking. Did I choose the wrong answer? | [
"Technically both are correct, but D is the better of the two choices. Ultimately this questions comes down to how you define your terms, which is one of the problems with Chemistry. ",
"Before going on, I need to mention that I love Chemistry and I believe it to be one of the most important subjects, but Chemist... | [
"D is technically correct, but incorrect nonetheless. ",
"Since the answer states two different elements that are non-metals will have a covalent polar bond, it takes into account that these elements are (1) dissimilar, and (2) non-metallic, resulting in a polar covalent bond between them. However, not all polar ... | [
"In all honesty, A is not really correct since it hasn't specified which atoms. As an example Chlorine is more electronegative than Sodium, NaCL, while very polar, is not covalent. If they had spent the time to simply specifying organic molecules this question would be a lot more clear.",
"Question is silly."
] |
[
"Is gravity a constant?"
] | [
false
] | Like at what point do we achieve weightlessness in space, is there an exact point? Also how is gravity strong enough to keep the moon in orbit, but weak enough to allow me to walk around? | [
"1) Weightlessness is when you fall at the exact rate as your surroundings. You can achieve weightlessness at any height, assuming you had somewhere to fall. If you're standing on a scale in a falling elevator, the scale would read zero.",
"2) The simple answer is just because the moon is more massive than you ar... | [
"I'm going to approach this with Newtonian gravity. There's a much more complete theory developed by Einstein that I imagine others might reference here called General Relativity. But Newton is close enough to the truth to answer these questions.",
"So let's go with weightlessness first. Suppose you're in a space... | [
"And the moon is traveling at over ",
"1 km/s",
". You're traveling at 0km/s, and for comparison, a car at 60mph is traveling at 0.0268 km/s. If you were traveling at 1km/s at that distance from the Earth, you'd miss the ground too.",
"Simplified: imagine a system of just the Earth and the Moon. Think of t... |
[
"If hydrogen and carbon are in abundance, why can't scientists 'manufacture' hydrocarbons?"
] | [
false
] | An increased supply would stabilise crude prices, which is good for producer and consumer — and with volume would become cheaper than traditional extraction. Is it at all possible? | [
"They can. It takes energy. We get most of our energy from burning the very things you want to make. Burning oil to make less oil is necessarily wasteful and more expensive than just using it directly. However, if we used another source like solar energy, this would be a way of getting \"fossil\" fuels without ... | [
"Let's review for a minute here. A natural hydrocarbon is the result of sunlight which once shined on a prehistoric plant. The plant used the sunlight to split H2O and CO2, producing H and C which it turned into sugars. The sugars contained only 1-2% of the original energy in the sunlight. Eventually this plant hap... | [
"Plus there's all sorts of other uses for hydrocarbons than fuel. Plastics are pretty nice to have."
] |
[
"Why can't we remember smells as well as sights?"
] | [
false
] | null | [
"At a technical level, we dont understand the brain at that level of detail yet.",
"However, a lot of this is a more evolutionary question than one about the underlying mechanisms. Think of asking 'why can dogs swivel their ears but humans cannot'. Mechanically, thats because we dont have the muscles, but really,... | [
"You don't remember sights that well either, your brain just convinces you that you do. You can go back to something that looks unrecognizably different from when you saw it last, your brain matches the general pattern and overwrites the non-matching characteristics in your (deteriorated) memory of how it looked, a... | [
"IIRC my neuroanatomy, the olfactory system (which processes the sense of smell) has pretty close connections to the hippocampus which codes for long term memory processing.",
"Smell is actually very powerful at eliciting memories and emotions."
] |
[
"Is it possible to make \"chords\" of visible light?"
] | [
false
] | In music, a major chord is formed by simultaneously playing a note, a second note at 5/4 the frequency of he first, and a third note at 3/2 the frequency of the first. Are there any special properties, or appealing aesthetics, of combinations of light waves that differ by simple fractions in this way? | [
"No, it isn't.",
"The ear and eye are very different beasts, the ear can pick up both pitch and intensity of sound. The ability to hear the sound at any pitch allows us to appreciate the harmonics.",
"The eye can only detect intensity. The reason we can see different colours is because we have 3 different colou... | [
"While the following tidbit might not be exactly what you're talking about, consider the color magenta. Magenta is known as an extra spectral color in that there is no single frequency of light that would produce such a color to one's retina. Rather to make magenta, multiple colors must be combined."
] | [
"The human eye can't perceive the exact nature of the spectrum, since it relies on just 3 cone cells. It can only see the \"average\" color. Two colors that additively create yellow (red and green, as in LCD subpixels) look like yellow, even though no actual yellow light is present. Also, unlike the human ear, our ... |
[
"Photon beam through an absolute zero crystal prism. What happens?"
] | [
false
] | Would the absolute zero temperature cause any weird effects? Such as slowing down the beam, messing with the visible spectrum, etc. | [
"The prism is a crystal lattice of atoms. ",
"Since it is at absolute zero, ignoring quantum mechanical subtleties meaning that this is impossible (absolute zero would mean exactly known momentum AND position, violating the Heisenberg uncertainty principle), the atoms are standing very, very still. Temperature es... | [
"Well, remember, absolute zero isn't a thing you can reach, it's a limit. Like light speed. You can get as close to light speed as you like, but never reach it. Same with absolute zero.",
"I'm sure that somebody with experience in optics might be able to come along and tell you about light NEAR absolute zero (... | [
"Often, the temperature T goes into an expression that looks like exp(-ΔE/kT) with k being the Boltzmann constant. If you happen to be interested in some kind of physical process that has ΔE comparable to kT you will be sensitive to even these incredibly tiny changes in temperature."
] |
[
"Does a container with a perfect vacuum in it float?"
] | [
false
] | null | [
"It would if the container weighed less than the volume of air it has displaced. Lets assume we have a 1 meter cube of pure vacuum, this would displace just over 1kg of air, and hence, if the container itself weighed slightly less 1kg, it would float.",
"However, at sea level, air pressure is about 100000 pascals... | [
"The first lighter-than-air crafts ever designed were ",
"vacuum airships",
". Nearly a century before the first hot air balloon flew."
] | [
"However none were actually successfully made. The application was just theorized."
] |
[
"If the international space station was not orbiting earth and just stood still as if it were held up on a pole or something - so it wouldn’t crash to earth, what amount of gravity would the occupants feel?"
] | [
false
] | I’m wondering about how much the gravity decreases at the height of the ISS. | [
"About ",
"88% as they do at sea level",
". The ISS orbits the Earth ~400km above the surface, which sounds high, but the law of universal gravitation uses the distances between centers of mass- so for something orbiting the Earth, it's from the center of the Earth, which is ~6000km. So, for something being ~64... | [
"That's an interesting question, as the OP asks about being stationary relative to the surface, not non-rotating relative to the COM, which would include some angular effects.",
"The centripetal acceleration (a) is:",
"a = r ω",
" ,",
"where r is the radius and ω is the angular speed in radians/unit time. G... | [
"What about \"centrifugal\"? forces?"
] |
[
"How do stereograms work?"
] | [
false
] | How do the optical illusions stereograms work? I understand it has something to do with the layering of 2-dimensional images, but could someone explain it further? Here are some examples. | [
"When you see something (e.g. a tree, a car, a tornado), you're actually seeing two images at the same time, one from your left eye and one from your right eye. Your brain interprets these images and comes up with a perception of the world with depth. ",
"A stereogram exploits this idea by showing your right ey... | [
"Ok, I understand that but you don't have to cross your eyes to see it do you? My friend said that he was seeing it and his eyes were not visibly crossed."
] | [
"Certain stereograms -not sure if any of the ones you've posted apply- can be seen both by converging the eyes (i.e. crossing your eyes) and by diverging your eyes (i.e. pretending to focus on an object far in the distance). Should one be this way, diverged eyes should appear normal. Nevertheless, most stereoscop... |
[
"How would you escape an autoclave?"
] | [
false
] | I recently started working at a lab where there are a few autoclaves, approximately 4 feet tall, 3 feet wide, and 6 feet deep. Definitely large enough to fit a person. What would you do if you were trapped inside? There doesn't seem to be any emergency escape button/cord on the inside to prevent this situation. How long would you have until you passed out/died from the pressure/heat? Has anybody else thought about this? Edit: Thanks for all the advice and stories! Very helpful | [
"This doesn't help you at all, but I work at a hospital and inside the morgue there is a big yellow sticker by the door that says ",
"YOU ARE NOT LOCKED IN!\nTURN KNOB REPEATEDLY TO ESCAPE"
] | [
"Ever considered cooking with it? I imagine it'd work like a slow cooker....\nTake a bone to the lab... throw it in the autoclave... add some broth, a potato. Baby, you got a stew goin'!"
] | [
"In college, we made lemon pepper chicken in an autoclave once. It was delicious and fell right off the bone. Maybe almost too tender."
] |
[
"Regarding the Demon Core?"
] | [
false
] | null | [
"Is it that neutrons are blocked by it because they're so big? But electrons (the ionizing radiation) is small enough to pass through?"
] | [
"It doesn't reflect ",
" of them. Many of them still escape."
] | [
"So when the core is going critical it's producing so many neutrons at an exponentially increasing rate and THOSE are the radiation?"
] |
[
"Would a rigid container whose contents were a vacuum such that the weight of the container was less than the weight of the volume of the air it displaced, would it float?"
] | [
false
] | [deleted] | [
"Yes and the idea has been around since 1670. The problem is finding a material strong enough and light enough.",
"See ",
"http://en.wikipedia.org/wiki/Vacuum_airship",
" for more info."
] | [
"Of course it would float, why wouldnt it? This is assuming you could build a material strong enough to support a vacuum that was light enough not to overpower the buoyancy from having a vacuum in the first place."
] | [
"Yes. In fact, a vacuum is technically the most buoyant thing you could fill a container with, though as others have mentioned, a container strong enough to withstand the outside air pressure without being crushed while still being lighter than the displaced air would be hard to find."
] |
[
"Does the parents fitness at the time of conception affect the metabolism of the child?"
] | [
false
] | [deleted] | [
"There is growing evidence that supports Lamarckian methods of inheritence. For a really thorough analysis check out the ENCODE project and literature involved in epigenetic inheritance. ",
"This is the best example I could think of"
] | [
"Yes, it can have a large effect (and it's actually the area of my research!) For example, children born to mothers after developing overt diabetes are around 10x more likely to develop diabetes in later life, compared to children born prior to maternal diabetes. (",
"link",
")",
"Similarly, children born a... | [
"This isn't the whole story but ",
"Gestational Diabetes",
" can be caused by a high sugar diet. There are many other drugs that have effects but I think they are less related to your 'fitness' parameter; such as alcohol and the wrong isomer of thalidomide."
] |
[
"How are the floaters I see in my eye in focus?"
] | [
false
] | People have asked about floaters on here before, but what I'm wondering about is how I can see them so clearly. If I hold a book a few inches from my face the text is too close to focus on, but floaters are in my eye, yet appear to be fairly in focus. How can that be? | [
"The closer they are to your retina, the sharper their shadow, and the more in-focus they will appear to be."
] | [
"Hmm interesting. Am I seeing them upside down? So an L shape floater to me might look like a 7 to someone looking in if they could see it?\nThanks!"
] | [
"No and yes. You see them \"correctly\" but an observer outside the eye would see the floater upside down because they see the image which is reversed. Surely you know that the brain again reverses the images, so it is a bit confusing to discuss what is upside down and what is correct."
] |
[
"On the link between \"information content\" and DNA"
] | [
false
] | I've been trying to do some research recently on DNA. I am involved in a long-term, email debate but it is very civil. We both agreed we'd use this as a method to increase our own knowledge of the subject. He seems to be arguing from Dembski's Specific complexity, stating that since DNA contains information (sent between DNA and received by the proteome) that there must be an intelligence behind it (paraphrased). I am in disagreement with this but am having trouble wrapping my head around the concept of information in DNA. AskSci hasn't been my first go-to. I have found a number of videos detailing how the genetic code arose and how evolution can increase the information within an existing genome. That said, I cannot find (or wrap my head around what I have found) a relatively easy to understand explanation on how DNA came to contain "information". I disagree with this definition of information, but still have no satisfying answer. I've searched high and low but thought AckSci would be a beneficial place to turn to. Anything way you guys can help would be greatly appreciated! EDIT: Clarification | [
"Dembski, as in William Dembski? The \"Creation Scientist\"? The one who is using the field(s) of computer science, search algorithms and neural networks to \"disprove\" evolution via \"No Free Lunch\"?",
"/r/AskScience",
" is not supposed to be a go-to place for people having arguments, nor as your magical sol... | [
"He seems to be arguing from Dembski's Specific complexity, stating that since DNA contains information (sent between DNA and received by the proteome) that there must be an intelligence behind it (paraphrased).",
"This is a combination of begging the question and a non sequitur. Call him on it. It's a logical fa... | [
"Everything contains information, pretty much by definition. How else could you identify anything? Information is any characteristic of an object, such as it's weight, color, size, chemical composition, behavior, etc. ad infinitum. DNA contains plenty of information, but other than the rather important nature of... |
[
"What would happen if you tried to light a match in pressurized oxygen?"
] | [
false
] | If you have a chamber of pure O2 ie: a hyperbaric oxygen chamber is it possible to light a match in that environment or would the atmospheric pressure be to much? | [
"Because of the abundance of O2 in the environment around the match, the entire match would burn extremely rapidly, in fact it may burn so rapidly as to essentially be an explosion."
] | [
"Many lab demos show that if you take a burning item and submerge it in liquid oxygen, it will burn VERY aggressively.",
"In fact, here's a demo of ",
"a hot diamond dropped into liquid O2 will burn away",
"The liquid oxygen is at room temp so it's boiling and very very very cold.",
"I believe the experimen... | [
"Would the increased pressure have any effect as to how quickly the match would burn? "
] |
[
"[Engineering] Would building a house in a glass box keep the house warmer in the winter and cooler in the summer?"
] | [
false
] | If you had a giant glass box, and then built a single-story 2 bedroom house inside of the glass box would the house stay warmer in winter? In summer, would the house stay cooler? Would the air act as an insulator? Thanks! | [
"I think there are two different things that you need to think about. First, having the house-in-a-box (and some air between the two) would help the house keep a more stable temperature versus the outside world. This isn't to say that the house will be intrinsically warmer or cooler, but rather that its temperatu... | [
"Could you make the box tall, and in the summer open the top so the chimney effect keeps the house cool, and then close the box in the summer to keep it warm?"
] | [
"If one assumes that the house has a heater then it would be warmer in the summer and colder in the winter. Warmer in summer because more of the suns light would get in and heat air that could then not escape. Colder in winter because glass is not nearly as good a thermal insulator as the stuff typically used in ... |
[
"Are there planets with mountains so high they extend past the atmosphere so you could literally climb your way into zero gravity looking over the curvature of the entire planet?"
] | [
false
] | Just a cool thing to imagine | [
"Atmosphere and gravity are two different things!",
"In terms of atmosphere, there isn't a hard cut-off where the gas just disappears - it slowly gets less and less dense as you go up. The International Space Station actually feels drag from the atmosphere and has to boost itself a little bit every now and again,... | [
"And, inconveniently, the mass of such a large mountain would likely create some degree of gravity on it’s own."
] | [
"This mountain would have to extend to geosynchronous orbit, which is about a third of the way to the Moon.",
"1/10"
] |
[
"In the line of evolution, has there been a point where prehistoric humans shared the same intelligence level as dinosaurs? Would that mean dinosaurs had a chance of human-like levels of intelligence if they didn't get screwed with extinction?"
] | [
false
] | [deleted] | [
"You seem to be under the assumption that evolution has either a goal or forgone conclusion that intelligence would rise over time, in a way comparable to humans. Sharks have been around as a suborder ",
"since the time of the dinosaurs",
" without approaching human-like intellect. Evolution is just the natur... | [
"You're assuming that evolution always drives organisms towards greater intelligence. Very high intelligence is one possible trait that, apparently, increased our ancestors' survival enough for it persist in the population. As one of the other commenters said, there are many lineages that have been evolving for mi... | [
"I am not an evolutionary biologist, but I am going to go ahead and say that anything that we would recognize as \"human\" or even \"human-like\" would be smarter than a dinosaur. ",
"Furthermore, there are a lot of cool theories as to why we are as smart as we are, and most of them include some characteristic (s... |
[
"Can someone explain the AU, Astronomical Unit?"
] | [
false
] | [deleted] | [
"We use the AU mostly to refer to distances within the solar system - for example, the distance from the Sun to Saturn, or to the Kuiper Belt. We also use it to describe similar distances in other star systems, say, the distance between two binary stars, or between a star and its planets. There's nothing special ab... | [
"It's arbitrary in that sense, but not arbitrary in that it's an extremely convenient thing for astronomers to use. So perhaps \"convenient\" would have been a better word than \"arbitrary.\" In either case, light years are neither, and that was my point :)"
] | [
"search the reddit for \"second\" There was an interesting thread a few days ago about defining the second. It all boils down to the babylonian affinity for sexagesimal. (and the large number of factors in 60) I think that particularly for degrees, there may be some coincidence with the number of days in a year as ... |
[
"If I tap my fingers to the beat of a song in my head, is there a delay between my thought of the song and the movement of my finger that I don't perceive?"
] | [
false
] | When I 'play' the song "Mary had a Little Lamb" in my head, I can tap my finger along with it, and it seems like my finger and my thought are in sync. But doesn't it actually take some time (hundredths of a second, I think) for muscles in my finger to respond to a command in the brain? So is the song in my head actually slightly ahead of my finger movements? Or does my brain make my finger move before the particular note enters my mind? Or is there no delay? | [
"Your brain is making your finger move so that your perception of your finger landing and the perception of the rhythm in your mind line up. In order to do this, the brain has to start the motion of the finger before the corresponding note hits. Your brain is thinking ahead without you even realizing it, and adjust... | [
"In musical terms this is called \"anticipation\" or \"anticipating the beat\". You have a memory or sense of language about how it's supposed to sound and, just like speaking in unison, it probably wasn't synced up the first time you tapped along to a song. Physical expression of rhythm is a learned trait. "
] | [
"Like how a bassist will begin to strum, or a drummer will bring their drumsticks down, a fraction of a second before a song starts? "
] |
[
"Is it possible for a particle to be completely still? If so, what are the implications?"
] | [
false
] | Shower thoughts. I became curious. | [
"\"Completely still\" depends on the observer's motion. Your question is equivalent to \"Is it possible for a particle to have a perfectly known velocity? (not necessarily zero)\" ",
"This is possible in classical physics (only in an idealized situation, of course). ",
"In quantum mechanics, however, it mean... | [
"Quantum mechanics is probabilistic. If we want to know where something is or where it's going, all QM gives us is the most likely position/momentum, which we call an \"expectation value.\" Formally, the expectation value is what we would expect the most common result to be if we measured an ensemble of identical s... | [
"OK.",
"In classical (Newtonian) physics, a particle can be completely still. However, \"completely still\" is not an absolute concept, because it depends on the motion of the observer.",
"In quantum mechanics, it is impossible, due to the uncertainty principle."
] |
[
"If at L1 and L2 between Earth and the Sun, an object would have the same orbital period as Earth, what is the orbital period between L1 and L2?"
] | [
false
] | Between L1 and Sun, the object has a shorter orbital period than Earth. At L1 it has the same orbital period as Earth. Beyond L2 an object has a longer orbital period than Earth. At L2 it has the same orbital period as Earth Then say if there was an object between Earth and L1, does that mean the object has a longer orbital period than Earth? If there was an object between L2 and Earth, does it have a shorter orbital period than Earth? How come the moon, in relative to the Sun, has the same orbital period as Earth, since it's between L1 and L2? Thanks! | [
"Take a quick look at Kepler's laws of planetary orbits, and you'll stumble upon his third law, which says for orbiting bodies (let's say planets) the farther away you are from the thing you are orbiting (let's say the sun) the longer your period is. The exact mathematical relation says that the period squared is p... | [
"Nope. Those ones are stable for the Earth-Sun system (and almost all systems as well)! In order for them to be stable the mass of the bigger body has to be about 25 times as massive as the smaller body, which is true for almost every system.",
"If something starts out at either L4 and L5, and is displaced a litt... | [
"How bout L4 and L5? Are they also unstable? "
] |
[
"How does the smoke of large wildfires affect insect populations?"
] | [
false
] | null | [
"Since you specified honey I'll respond regarding honey bees. It unlikely to have any effect on honey prices as honey is produced world wide and on that scale of things wildfires are very localized. You could see some rise in locally produced honey if there is a specific crop for that area that was destroyed by th... | [
"A ",
"paper",
" published less than 2 months ago actually covered this. Haze smoke had a negative effect on the development of butterflies, from their health to length of development time (slower is bad). However, the cause is not likely to be of suffocation or particle obstruction in their breathing tubes (tr... | [
"Wow, what a comprehensive answer - thank you!"
] |
[
"How does Boron's ability to absorb neutrons work and does absorbing neutrons affect the atom?"
] | [
false
] | Boron is often used in nuclear reactors because of its ability to absorb neutrons. How can Boron do this without becoming super heavy or otherwise changing itself? | [
"The boron ",
" change. It undergoes neutron capture reactions. Neutron capture looks like:",
"X + n -> ",
"X + γ.",
"That means that the nucleus is transmuted to a heavier isotope of the same element, and a gamma ray is released."
] | [
"I'm so disappointed. "
] | [
"\"Beaver\" isotope?"
] |
[
"How were the water masses on earth and how did they function before trees or plants appeared?"
] | [
false
] | So, I before plants ever existed I suppose there were already water masses like oceans, seas and, I suppose, the cycle of rain water already existed. Therefore there must have existed already rivers, right? Should we imagine that time where plants didn't exist then like naked ground and rock with rivers running down to the sea? The question might be a bit obvious for some but I have a hard time imagine such a landscape. Would it have been like say... the Colorado Canyon but without any kind of plant or tree around? excuse any typo, I'm not a native English speaker and you might find errors in the text:) thanks in advance! | [
"One aspect of your question that is discussed quite a bit is what rivers were like prior to the evolution of land plants. Specifically, there is a lot of evidence that ",
"meandering",
" rivers require significant cohesion of their banks to form, where this cohesion is usually provided by vegetation and that i... | [
"Thanks for such a detailed answer! I think somehow I had imagined them like braided rivers, but that was just a lucky guess. Then the cycle of evaporation and rain would have been essentially the same, right? Was the earth as warm as it is today? And would that somehow affect the formation of rivers?"
] | [
"This is too broad to be answered. Abundant vascular land plants developed in the ",
"Silurian",
" (though the colonization of land by simple photosynthetic organisms began in the ",
"Ordovician",
"), so the period before land plants represents > 4 billion years of Earth history. You would need to narrow th... |
[
"Would you still be \"weightless\" in a geostationary satellite?"
] | [
false
] | This mentions that astronauts in the ISS are subject to 90% of the gravity you and I are feeling here on the surface. The illusion of weightlessness is due to the fact that they're in "freefall" around the Earth at orbital velocity, and if we built a tower that high we could walk around unhindered. So what if the satellite was geostationary? Would the zero-G "freefall" occur or would it behave like you were standing in an orbital-height skyscraper? | [
"Geostationary satellites are still in freefall, so you'd still feel weightless.",
"A geostationary satellite orbits the Earth with an orbital period of one day (as compared to, say, the ISS, with an orbital period of around an hour and a a half), which is why it can stay over the same spot on the Earth. But is ... | [
"For one thing, geostationary orbit is a lot higher than where the ISS is, so Earth's gravity is only about 2% as strong there as it is on Earth. You would still feel weightless on such a satellite, just like on the ISS, and for the same reason.",
"So what if the satellite was geostationary? Would the zero-G \"fr... | [
"Absolutely correct. Geostationary satellites are still in free fall, their speed is simply matching the direction and speed of the earth's rotation."
] |
[
"Why do the various SSRIs work differently?"
] | [
false
] | If they all work by blocking serotonin reuptake, why do they seem to have differing efficacy among patients? Are there other active elements that differ from one SSRI to another? Are the differences really enough to warrant a doctor prescribing paroxetine for a patient when sertraline doesn't produce the desired result? | [
"The SSRI is a general mechanism. Each drug has slightly different receptor affinities, which can translate to substantial enough differences in drug activity as to warrant a bunch of different drugs in the same class. Switching to a new drug can make all the difference. ",
"This isn't limited to SSRI's. Ther... | [
"Just to branch off of this, these drugs may have different pharmacokinetic properties as well. Differing half-lives, ability to cross the BBB, metabolism, liver enzyme interaction, etc. all influence the drug's ability to function well in a specific patient or condition."
] | [
"Selective Seretonin reuptake inhibitors aren't really quite selective, and have activity at norepinephrine and dopamine transporters, they bind with different affinities to their transporters, and they will be distributed through the body slightly differently. That will explain why they are differences.",
"Conne... |
[
"What causes light refraction at the leading edge of an airplane wing at cruising altitude/velocity?"
] | [
false
] | I noticed it once and now I see it every time I fly (unprecedented exit row streak). It's a very thin "layer" if you will where the light is refracted. It's barely noticeable, looks like it can't be more than 1 cm, but most definitely there. Also, the light appears to to bend at an angle towards the fuselage, not towards the tip of the wing. I get that light refracts as it transitions between two mediums, and I get that moving air behaves like a fluid, but there is most certainly moving air ahead of this very thin "layer" where light is refracted. Why just at the leading edge? | [
"The refractive index of the air varies with its density. This can be observed when you look through a column of rising hot air over a flame. The hot air is a lower density than the room temperature air, and the difference in their refractive indices causes distortions in the light passing through.",
"I suspect... | [
"I'm not disagreeing with either of you. It's just that, although temperature was used as an example of refraction, it wasn't stated as a reason this phenomenon is observed on a wing. Hence \"in addition...\""
] | [
"Agreed. The air at the leading edge is the highest pressure. The air just above that moving over the wing is at a much lower pressure. The two density differences so close together causes a visual difference."
] |
[
"What Would I Have To Do To Power My House Completely Off Renewable Energy?"
] | [
false
] | null | [
"Depends a bit on how \"off the grid\" you want to go.",
"The average American household uses around about 14 000 kWh of electricity a year ",
"(source)",
". This means about 38 kWh per day. This is quite a lot. A well set-up 1.5kW solar panel system in Sydney, Aus would produce about 6kWh of energy per day o... | [
"Some of the answers below are good, but I have actually worked as a renewable energy contractor and I can tell you the first thing you are going to want to do has nothing at all to do with your renewable energy system.",
"You are going to want the most efficient home you can buy/build. For every dollar you spen... | [
"I should also add, the price of these systems really depends on a lot of things, including the kind and amount of government subsidies in your area. You can dramatically reduce costs using the methods I mention above."
] |
[
"Is the useful energy released from ATP losing its phosphate group... mechanical energy? Is everything that my body does a result of tiny bomb-powered propulsion engines?"
] | [
false
] | I was trying to figure out what kind of energy is released when ATP is broken up, and I came across . Most of the comments are a little over my head, but the top comment mentioned that proteins have binding sites for ATP, and that the release of the phosphate group causes the proteins to change shape. The description in the comments almost makes it sound like the release of the phosphate group propels the rest of the protein in a predefined way like a carefully calculated little explosion. A tiny rocket propulsion. Am I wrong to imagine that this is a little like changing an asteroid's shape and trajectory by strategically detonating bombs on specific points on the asteroid's surface? Does this mean that when my muscles move, it is the result of proteins contracting under the force of billions of tiny explosive forces? I hope so. Oh please let it be true. I want to be a machine moved by billions of tiny rocket-propelled proteins. | [
"I hate to break it to you but it isn't mechanical energy or like small explosions. It's what is often referred to as chemical energy or chemical potential energy. In essence, there are a lot of different bonds between atoms, for example, a Carbon-Carbon bond such as in graphite or diamond, has a different energy l... | [
"http://www.researchgate.net/publication/10774066_ATP-induced_conformational_changes_of_the_nucleotide-binding_domain_of_NaK-ATPase/file/e0b4951a75c5fbef88.pdf",
" ",
"Molecules like sodium... right. Honestly it seems like either you have a secondary school level education in this or English isn't your first l... | [
"It's a paper not an article, and I'd say conformational change is pretty mechanical. Why do you keep putting that in quotes? I was making the point that sodium is not a molecule."
] |
[
"What would happen if a very large amount of \"Pharaoh's Serpent\" was ignited?"
] | [
false
] | [deleted] | [
"Firstly it can't create mass, it changes form and increases its volume. I would assume that if you did ignite that large of an amount the same reaction as before would take place just on a larger scale. The actual rate of the reaction likely would not change due to an increased reactant quantity, and your limiti... | [
"Didn't southpark do an episode on lighting the worlds largest \"snake\" firework? ",
"Seems like that would be the result."
] | [
"http://en.wikipedia.org/wiki/Summer_Sucks",
"Does that answer your question? ;)"
] |
[
"If a child were to not EVER come in contact with another human/lifeform, how might it act?"
] | [
false
] | [deleted] | [
"They're what we call ",
"a feral child",
" (not the most sensitive name ever). The most famous case is ",
"Genie",
". ",
"tl;dr human contact is very important for proper development. What's more, we have critical periods of development (think about how hard it is for adults to learn new languages) where... | [
"I still remember my first year psychology professor saying, slightly annoyed, \"You know we could skip most of this stuff if they would just kidnap a baby and lock it in a dark room for 15 years\""
] | [
"Fitting username?",
"Yeh, that's the frustration with psychology. There's so much we could study if it weren't for pesky ethics. Most of the seminal studies would have 0 chance of being approved now. \"Oh, you want to terrify a baby over and over to see if it gets scared of a toy? Sure, that seems alright!\""
] |
[
"Do the various dog breeds derive from a common dog ancestor, who derived from wolves -- or, does each dog breed correspond to a domestication of a corresponding wolf breed?"
] | [
false
] | In general, the diversity of dog breeds is a mystery to me. | [
"All dogs derive from a single domesticated wolf ancestor--or possibly (they're not sure) wolves started living with human ancestors and diverged from the rest of the wolves and so the wolves that lived with human ancestors were their own separate breeding group for tens of thousands of years before domestication.... | [
"Thank you!"
] | [
"This domestication can actually be seen in foxes. It hasn't taken many generations to produce dog like traits like floppy ears and docile behavior in ",
"foxes",
". "
] |
[
"Since DNA degrades as we age, would a clone made with an older person's DNA sample have a shorter life expectancy than a clone made with a young person's DNA sample?"
] | [
false
] | Possibly a related question: Why is it that humans are able to produce offspring with "fresh" DNA, yet we are unable to maintain the integrity of our own DNA over time? Edit: Thank you, everybody for your very informative answers. TLDR: clones are essentially as normal as if they were naturally born. There is a very fine balance between healthy cell repair and cancer, and we haven't quite figured out how to control it reliably yet. | [
"Maybe but one of the first things that happens in cancer cells is that a lot of those mechanisms get turned back on"
] | [
"So if these repair mechanisms can be triggered in humans, is this how aging could be slowed?"
] | [
"So if these repair mechanisms can be triggered in humans, is this how aging could be slowed?"
] |
[
"What factors could you change to direct evolution?"
] | [
false
] | Ignoring hands-on selective breeding for a second, if you wanted to make a species evolve to be suitable for a given habitat, what factors would speed up the process? I'd imagine you change their habitat gradually from their current one towards the desired one, but what else would speed up the process? Anything else? | [
"Larger is better, since it means their is more variation and a higher probability of mutations. ",
"Radiation is mostly causing damage to germ cells, and I do not know if or how it could effect a population in a whole. different radiation treatments can have different effects. A danger is created so many defunct... | [
"You can't really change the process of evolution unless you do something like genetic engineering. What you are really talking about is setting the parameters under which natural selection will take place (though I guess in this case not so natural). ",
"If you have a large enough population with a large degree ... | [
"Well you could put it into the water supply, which would probably be the easiest delivery mechanism. I'm not sure if you are thinking that they are in a farm like environment or free range. If you had some sort of relatively contained water source, it would be best, so as to avoid dilution of the chemical and to p... |
[
"Why are suicidal thoughts such a common side effect of so many medications?"
] | [
false
] | null | [
"I’ll add that some antidepressants (like Prozac) have black box warnings for increased risk of suicide because these medications can improve a person’s motivation before they start to improve their mood. Typically we say it takes up to 6 weeks to see a full benefit from antidepressants. Now, say you’ve got a patie... | [
"This is why we stress that patients should be reviewed by their prescriber 3-4 weeks after starting treatment. 'It may make you feel worse before you feel better' is a warning I've said a thousand times as a pharmacist."
] | [
"Your mood is regulated by chemicals in your body and brain, if you take drugs or medications that can interfere either directly or indirectly with any of these pathways it can cause you to feel low or stressed or strung out. This can result in you having thoughts of suicide. It's important to know that while we ca... |
[
"Why can the lone star tick bite make you allergic to red meat, if that very same allergene your body starts reacting to has always been present in the meat itself?"
] | [
false
] | So I've heard that getting bitten by the lone star tick will make you allergic to red meat, specifically to saccharide "alpha-gal", present in most mammals, except humans. I wonder why we don't develop this allergy by eating the meat itself. Wouldn't that sugar circulate the body and be detected as foreign anyway? I'm sure I'm missing an important mechanism here, I just can't figure out why the body is fine with it as long as it's exclusively eaten, but after a bite you can't eat it anymore. I'm really curious about this acquired allergy. | [
"It doesn't happen when we eat alpha-gal because alpha-gal is not dangerous. The immune system confuses alpha-gal with the dangerous tick proteins after exposure to the tick proteins. ",
"Immune cells generally learn to attack proteins. A protein is shaped kinda like a puzzle piece. It has a shape on the outside ... | [
"This is a great explanation, but worth noting that \"Alpha-gal\" typically refers to asparagine linked glycans (oligosaccharides on glycoproteins) that are terminated with alpha linked galactose. The allergy is still caused by a protein, it's just the sugar component acting as the antigen. Glycans are fairly com... | [
"To answer part of your question: You don't develop allergies from eating the meat itself because we digest the meat before we absorb it. In other words, our digestive systems take whole proteins and break them down into amino acids before we can absorb them. Whole proteins in the blood stream trigger immunologic r... |
[
"How does the Arecibo Observatory account for all the water and debris that might accumulate on it?"
] | [
false
] | As you can see this radio telescope is located on the ground where (I think) water and debris may easily enter. Do the observatory personnel somehow clean all the water and dirt up even after a heavy rainfall? | [
"They have a hole in the center through which excess water and debris are drained.",
"More importantly, the radio waves which they observe are largely unaffected by any debris or water on the dish that may still be there after the rain has stopped."
] | [
"Drained to where? My impression was that a karst sinkhole connects with a natural groundwater system of some kind, is that the case here? Or is this drain man made?"
] | [
"I don't know what their drainage system is like.",
"But I am quite sure they have something suitable for the amount of rainfall that would fall on a surface of that area.",
"I got curious and looked around:\nThe amount of precipitation they get on average ",
"annually",
" at Arecibo is 54.5 inches. The ave... |
[
"Ask science: Are there atoms floating through space (like small particles we can't see but are everywhere) or is it mostly empty? Would the suns gravity effect something so small?"
] | [
false
] | This is bottling my mind right now.. you know, like when your mind is in a bottle. edit: oops typo, should be "affect".. that sort of thing usually drives me crazy when others do it..that's what I get for posting something late at night whilst stoned! | [
"Yes, there are atoms floating around in space. Gravity affects them, but not very much, and it turns out that radiation pressure (or getting hit by light) affects them much more."
] | [
"Are there atoms floating through space",
"Yes. No doubt about it.",
"Would the suns gravity effect something so small?",
"Yes -- gravity affects all matter. It happens that, for small masses in the solar system, solar radiation pressure might easily be a more powerful force, and drive small particles away fr... | [
"I think the problem is that the AskScience reddit doesn't have that feature enabled."
] |
[
"How many tumours/would-be-cancers does the average person suppress/kill in their lifetime?"
] | [
false
] | Not every non-benign oncogenic cell survives to become a cancer, so does anyone know how many oncogenic cells/tumours the average body detects and destroys successfully, in an average lifetime? | [
"I don't think we can reliably estimate how many \"pre-cancers\" a healthy immune system can detect and destroy, but one of the major complications after a solid organ transplant is the risk for developing cancer due to the severe immune suppression needed to prevent transplant rejection. According to this article ... | [
"Wow. This is maybe the best answer I have ever seen on here. With citations, source and everything!"
] | [
"I’ve had a transplant, and I was told forever. Though the longer you have it, the less you need. I’m 5 years out and still at full day 1 dose levels. I have an overactive immune system, so we’re struggling to fight off the rejection."
] |
[
"What is an 'observation' in quantum physics?"
] | [
false
] | Having read about quantum superposition, an observation is said to collapse the superposed state, but what is an observation? is it merely photons bumping into the particle we're trying to observe? or is it interpretation by a "conscious" observer? if it is the former then almost every place is filled with some kind of radiation (if not anything at least thermal radiation) which would make it almost impossible for anything to be in a superposed state anywhere. | [
"Imagine that you have a whole universe (or system) with a single particle in it. There's just one particle described by a very simple wave-function.",
"But how do would you know that there's a single particle? You observed it by sending some other particle at it. ",
" And since there is ",
" a single particl... | [
"Yes, Schrodinger came up with the thought experiment to show how ridiculous the Copenhagen intepretation is. "
] | [
"Isn't this the critique that Schrödinger's cat is supposed to represent?"
] |
[
"Ideas can't hurt...can they?"
] | [
false
] | In discussions I often hear the claim that ideas cannot harm people; however, I suspect that they can. From my understanding, there is research showing that stress is detrimental to physical health. I am wondering what evidence there is demonstrating that ideas, perhaps those of ideologies, actually have physical effects on people. Are there ideas that can like malicious software attacking human hardware? Is there much evidence backing up nocebos such as the bone of death? Can thoughts kill? If ideas can harm us, what are scientifically backed ways of inoculation and defense? | [
"The idea of harmful ideas, or images is common in science fiction. One of my favorites is \"",
"BLIT",
"\" by David Langford, about an image that is fatal just to look at. But as far as I've been able to tell, sci-fi is all they are. There's no evidence of any specific meme or thought-form that causes physical... | [
"I'd be willing to bet that the human nervous system is far too robust to be hacked by some BLIT style attack, or similar things I've read in stories (like a tune so catchy that anyone who heard it would just waste away humming it). We've got built-in \"get used to the stimulus\" and \"get bored of the stimulus\" ... | [
"I'd agree. Humans are too good at perceiving, inventing, and communicating ideas and information. If any members of our species were susceptible to mental-death-by-meme, they were probably weeded out of the gene pool shortly after we invented language.",
"Chronic stress can cause cause long-term health issues, b... |
[
"How were ancient rope suspension bridges built across large gaps in terrain?"
] | [
false
] | Specifically how were they built above large drops? Would they need an extra long rope so they could climb down and then up to secure it from the other side? | [
"There were a few ways to do it, but one common way was to get one or two long pieces of thin string or rope across, then use that to pull a larger rope across. ",
"One method was to tie two pieces of light rope to an arrow and shoot the arrow over the river. One of the ropes would be tied taught at each end. The... | [
"Check out the ",
"Wikipedia article",
" about it. The section titled “Charles Ellet, Jr.'s temporary bridge” talks about it."
] | [
"Would you happen to have a source for that Niagra Falls bridge? Seems like a very interesting way to do it, I'd like to read more about it!"
] |
[
"Do languages affect our ability to feel different types of emotions? Would a bilingual person feel a wider range of emotions due to knowing more emotional vocabulary?"
] | [
false
] | [deleted] | [
"Linguistic relativity is the idea that language affects thinking. The strong version of this hypothesis is that languahe determines thought. Without a word for a concept, one cannot think of that concept. However, this idea is near universally discredited. There is a weaker hypothesis, that language influences tho... | [
"Excellent point there. I don’t know about ",
" more emotions, but a polyglot would be able to ",
" subtleties of emotion by borrowing words from other languages. If I could pick a second language, it would be German. They have (very long) words for amazingly specific things. ",
"Here is just one list of wor... | [
"Excellent point there. I don’t know about ",
" more emotions, but a polyglot would be able to ",
" subtleties of emotion by borrowing words from other languages. If I could pick a second language, it would be German. They have (very long) words for amazingly specific things. ",
"Here is just one list of wor... |
[
"Why are some acetylcholinesterase inhibitors classified as poisons and others as safe pharmaceuticals or even nootropics?"
] | [
false
] | Solanine is a poison in potatoes and sarin is a nerve agent/chemical weapon while galantamine is a pretty safe pharmaceutical and huperzine A is an OTC nootropic, despite the fact that all of them are acetylcholinesterase inhibitors. Why is that? | [
"Side effect profile.",
"Solanine is a saponin, so it destabilizes cell membranes. Cell toxins don't make good medicine.",
"Sarin is an irreversible inhibitor, which means that it binds to the cholinesterase enzyme covalently. Replacing these enzymes can take up to a week, so the increase in acetylcholine inevi... | [
"AChE inhibitors are used for treating Alzheimer's but so far, they don't seem to be that beneficial. Alzheimer's is believed to be caused by the death of cholinergic neurons, and AChE inhibitors would result in less ACh broken down and thus more ACh present. However, Alzheimer's is more complex than that and has o... | [
"I'm going to ignore the Altzhiemer's treatment bit; I'm speaking generally here. ",
"If the effects were identical, and the only difference were the potency, then yes. However, it's rarely that simple. It's pretty typical of chemicals that affect neurotransmission to have more than one effect."
] |
[
"When you wash your skin with lukewarm or hot water after you’ve been in freezing temperatures, why does it feel like the skin is burning? Is your body actually in danger or are the nerves misinterpreting what is happening? Are there other examples of this situation?"
] | [
false
] | null | [
"This happens because when your body gets cold it constricts blood flow to the extremities first so that it can maintain heat in the core areas of the body such as the brain and and abdominal. This causes nerves to shut down in the extremities which is why you don't feel as much pain when you are cold and any pain ... | [
"Most nerve cells in humans don't send signals all the time. A thermal receptor in your skin does not constantly report how warm it is, but reacts to change - because this is the interesting information for your brain to take action. In our skin, we have two types of thermoreceptors - one that reacts to 'cold' and ... | [
"Running a freshly frostbitten area under even room temperature water can actually cause much worse damage to the flesh. On the other side of things placing severe burns under cold water will cause it to blister faster and more agresively. I believe under normally safe temperatures it just feels like it is burning,... |
[
"What’s the point of flightless birds? Why didn’t they evolve additional limbs if their wings are effectively useless?"
] | [
false
] | null | [
"Hi thomas_ja thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the follo... | [
"Earth sciences "
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"This question is based on fundamentally flawed premises. Please conduct some background research and revise your question if you wish to resubmit.",
"It suffers from issues listed in the AskScience ",... |
[
"Is it possible to have a black hole so small that its effects on its surroundings are negligible?"
] | [
false
] | null | [
"One theory is that yes, you can have a black hole with a mass of only a few thousand kilograms and an event horizon smaller than an atom. The problem is that thanks to Hawking radiation, the lifetime of a black hole like that is short unless you feed it matter."
] | [
"A black hole has no more mass or gravitational influence than the matter that it is made of, and so if you were able to make a black hole by smashing together two hydrogen atoms, it would have the same effect on its surroundings as the gravity of a helium atom - negligible. "
] | [
"Say, it was possible to keep such a black hole sustained. Would it be something that we could see and possibly get close to ?"
] |
[
"Why Isn't There Nothing? (Non-Philosophical Approach)"
] | [
false
] | null | [
"I would add that consciousness only exists where it can; in parts of the universe where nothing exists, there is no one pondering why nothing exists. Thus, if nothing existed, there would be nobody to realize that this was the case."
] | [
"Sorry, I know you're aware, but this is much more philosophy of science than science. So you may want to consider ",
"r/philosophyofscience",
" instead actually."
] | [
"Thank you. I'll look into this venue as a location to pose this inquiry. "
] |
[
"How does running effect gene expression? What does that mean?"
] | [
false
] | I have heard that when people run on a consistent basis, that it have a positive effect on gene expression. What does this mean? If someone who did not run before began to run consistently, what changes would one witness in that person in terms of gene expression? | [
"Im on mobile, so this will be quick with a source. But, stresses on the body causes differential gene expression to create proteins designed to help the areas that are stressed. Since we are not as physically charged as our prehistoric ancestors we don't have the same amount of gene expression in certain areas. It... | [
"Just about any activity you do a lot has some effect on gene expression. ",
"Ever notice how you get tired and/or are physically bad at some things, but the more you do them, the better you get? That's gene expression. Even tolerance to alcohol or drugs is gene expression, ultimately. Some things get up reg... | [
"Gene expression simply refers to the types and amounts of transcripts(RNAs) produced by genes in a genome. ",
"There are many ways and multiple levels at which gene expression can be controlled. Many of these level have a kind time frame associated with them. For example, DNA binding proteins can turn expression... |
[
"Forced and sympathetic vibrations"
] | [
false
] | What's the difference between forced vibrations and sympathetic vibrations? For example, a guitar string forces the body of a guitar to vibrate at the same frequency as the string. Forced vibration or sympathetic vibration? | [
"I don't see how this explains the difference between forced and sympathetic vibrations though."
] | [
"The key to understanding sympathetic vibrations lies in understanding the concept of damping: ",
"http://en.wikipedia.org/wiki/Damping",
"Depending on the damping of our system, there will exist certain resonant frequencies at which driven oscillations will increase in amplitude and undriven frequencies will \... | [
"To clarify: \"sympathetic vibrations\" are oscillations which are exited indirectly by our driver (probably through elements which are not themselves highly resonant, and which will not to continue to resonate long after the source is turned off), and can continue to resonate after the source is turned off."
] |
[
"Why are suicide rates rising despite all kinds of new anti-depressants and therapies?"
] | [
false
] | null | [
"It'd be a good time to point out that that is the way all medicine is practiced. Are you at a risk of a heart attack or stroke? Let's proscribe you some anticoagulants, like heparin or warfarin. If we have a hard time maintaining the numbers we want with warfarin, go back to heparin... ",
"People's bodies are ... | [
"I don't believe that suicide rates ",
" rising. ",
"According to these OECD data",
", suicide rates have remained fairly steady. You would expect an increase in the ",
" of suicide as the population increases. It is still interesting to speculate about why suicide did not decrease as our antidepressants g... | [
"Same goes with somatic medicine. Knowledge of aetiology is not necessary in order to treat an illness."
] |
[
"What is the ‘curvature of spacetime?’"
] | [
false
] | In General Relativity, gravity is the curvature of space time, and it makes sense to me how objects can move as a result of the curvature of space, but I’m having a hard time (hah) seeing how time gets into the picture. Specifically, what does it mean to say that time ‘curves’? Curviness is a spatial property, by definition. Is it a metaphor for something deeper? Or am I totally missing the point of general relativity? | [
"Curviness is a spatial property, by definition.",
"No, it doesn't have to. Mathematicians have more general definitions of curvature. You could call it \"deformation of spacetime\" if you like.",
"Take a flexible cube, where places of equal height mean things happen at the same time and left/right/forward/back... | [
"Curviness is a spatial property, by definition",
"This thought comes from our oldest and most fundamental understanding of geometry, which was formulated in large part by Euclid. You might have ever heard the term \"Euclidean Geometry\" or \"Euclidean Space\". At the time of its creation, it was an attempt to ... | [
"They don't get applied to time, but to ",
". Time for any given observer is defined by choosing a certain direction within that 4-dimensional non-Euclidean space, with distances along the time axis measured in metres via",
"x",
" = c·t"
] |
[
"When did humans start to cook their food?"
] | [
false
] | And why? Obviously we can survive without cooking meats, but now most people (in the US) have only had raw meat a handful of times, if ever. What sparked this change? | [
"https://www.google.com/search?hl=en&site=&q=when+did+humans+start+to+cook+their+food&oq=when+did+humans+start+to+cook&aq=1v&aqi=g-v2g-j2&aql=&gs_sm=e&gs_upl=543l6069l0l7398l29l25l0l1l1l0l363l4070l2.17.3.2l24l0"
] | [
"We can survive without cooking ",
" meats, many however cause illness and seeing how it was long in the past, almost certain death. Most people stayed in one area so they only really had access to a few types of meat, so they couldn't get meat that they could eat raw. Also, they had very little sanitation, so ra... | [
"There is some evidence that suggest that we have been cooking food prior to even being human, with Homo Erectus (learned this in arch but here is the wikipedia on them ",
"http://en.wikipedia.org/wiki/Homo_erectus",
" )",
"look at 'use of fire' and 'sociality' in sociality it suggests that they were believed... |
[
"How often do new craters appear on the moon?"
] | [
false
] | null | [
"I don't know if the results of the Lunar Impact Monitoring study have been published yet, but they've spent much of the past two decades observing the near side of the Moon when it's over halfway in shadow to try to guess the rate of impacts. Because the lower end of impact velocities is still outrageously high, ... | [
"Quite frequently, like every day.",
" ",
" ",
"Source",
"So, in less than 4 years, and by looking at 1/15 of the lunar surface, they detected 222 craters larger than 10 m across. Extrapolating a bit, that's 222 x 15 / 4 = 832 new craters/year, ",
" across the whole lunar surface."
] | [
"I'd like to add that many planetary scientists would consider the moon a planetary body, and one of the criteria is having cleared its orbit / path of debris."
] |
[
"Are the “good” neurotransmitters produced when we exercise caused by the physical act itself, or the feeling of accomplishment from achievement?"
] | [
false
] | I apologize if this is an ignorant question/if I used the wrong label, but everyone is telling me to exercise to beat my depression (no worries I’m very happy and on meds). They always cite “endorphins!!” - I feel happier immediately after I finish exercising, but I also notice that more than anything I’m just proud of myself for the accomplishment. Does that have any bearing on the “happy chemicals” production, or is it all from the physical exertion? | [
"This question really has two parts, and I think you're mixing things up a little.",
"One side effect of running, or any other vigorous aerobic exercise, is that your body will release endorphins. Endorphins are a class of endogenous opiods. When opiods bind to opioid receptors in the in the ventral tegmental are... | [
"That makes a lot of sense actually, and yes, I always wondered why people were connecting depression to it because I know my medication is an SSRI, as are many others. Thank you so much for the thoughtful response and taking the time to sort it out, I really appreciate it!! "
] | [
"I thought that one of (not saying it is THE) the mechanisms involved is increased BDNF production after excercising. \nA quick google search gives quite a few hits but I doubt one conclusive answer will be given.\nA friend of mine finished her thesis on how depression comes to be and focussed in particular on the ... |
[
"Anthropology/History question: Is there a documented shift from polytheism to monotheism throughout the 'evolution' of a civilization? If so, what would cause this shift?"
] | [
false
] | I'm wondering how and if the Romans abandoned their plethora of gods. Or the Japanese, their multitude of spirits like Amaterasu (and other Shinto deities). Or the Vikings, their Norse gods. How does this shift happen, and what contributes to the persistence of widescale polytheism, for example Hinduism? Is it inevitable except for special circumstances? | [
"Not qualified to speak about the others, but the Romans started to abandon their plethora of gods roughly when Constantine converted to Christianity and, in the years following, he and his successors outlawed pagan religions and made Christianity the official religion.",
"See here."
] | [
"They all converted to Christianity. Sample size = 1"
] | [
"This isn't related directly to your question, but to something you said. This is my first post on ",
"/r/AskScience",
" so sorry if I'm breaking any rules.",
"Hinduism isn't a polytheistic religion. It is actually monotheistic. While it does have a large pantheon of deities, all of those deities are just dif... |
[
"Why are Newton's formulas considered laws, and Einsteins formulas considered theories?"
] | [
false
] | Einstein created the "theory of relativity". Newton however, made "laws". How are the two different? | [
"Perhaps contrary to the usage of \"theory\" and \"law\" in general language, \"theory\" is really the stronger term in science, a theory is more complete.",
"As I understand it, a law is an observation, an expectation. We see something happen so we write it down and we expect if we do the same thing over and ove... | [
"Thank you! Very clear and descriptive answer."
] | [
"A law is a description that, under normal circumstances, can always be reproduced. Like the OP mentioned it does not try to explain, \"why\" and merely concerns itself with, \"what.\"",
"A theory not only goes a step further and explores, \"why\" but there is one more caveat: A theory has never been disproven. A... |
[
"Does an insect, like a fly or a mosquito, have itches?"
] | [
false
] | null | [
"Yes, if their exoskeleton gets irritated. (Itch: An uncomfortable, irritating sensation that creates an urge to scratch that can involve any part of the body.) For example, put a drop of formic acid on a cockroach's abdomen, and it will rub the area with its legs to clean it as it's irritated."
] | [
"How extensive is the nerve system in the exoskeleton itself? I was under the impression that it was just made of (nonliving) chitin."
] | [
"Well it's comes down to how insects breath. So in a way what gets irritated is the tubes throughout their body called trachea."
] |
[
"If no two particles can occupy the same space and the center of a black hole has infinite density, do particles at the center of a black hole get infinitesimally close, infinitesimally small, or both?"
] | [
false
] | null | [
"Actually, it's not true that no two particles can occupy the same space. The statement is that no two ",
" can occupy the same quantum ",
". This is called the Pauli exclusion principle and is the effect that creates electron and neutron degeneracy in white dwarfs and neutron stars respectively. Specifically, ... | [
"If you could answer that and related questions, you would have offers from every research body and university in the world within the week."
] | [
"Since no information can escape a black hole",
" we can't really be certain. I don't think its constructive to think of objects existing within a black hole. Are you familiar with objects being stretched as they approach a black hole? Basically, the gravity well grabs one end of the object more strongly than ano... |
[
"Which side of the \"health vs weight\" debate has the greatest amount of supporting evidence?"
] | [
false
] | As I understand it the two opposed views are as follows: Health and weight are not causally linked, and many people who are very overweight are very healthy. Health and weight are causally linked; excess weight is a health risk, and causes health risks in its own right. If I am oversimplifying please correct me as I'm basically paraphrasing what I've heard from various people. | [
"It's reserve. You have a certain capacity for stress on your body before physiology becomes pathology, and it's both cumulative and synergistic.",
"Say you have a bridge. It gets a lot of traffic. It is also subjected to high winds frequently. It hasn't been inspected in a while. There was an earthquake a few ye... | [
"\"Reserve\" is a general term used in a lot of organ systems, usually applied to single organs or organ systems. Here, I'm applying it more broadly. An example would help, I think. Pulmonary reserve is probably the easiest to understand.",
"Assuming you are an adult male, sitting in front of your computer (playi... | [
"But that doesn't mean that being overweight is healthy, it just means that the person hasn't reached their reserve yet. ",
"Be very careful with your terms here! ",
"I think what the OP might be getting at is that this ",
" necessarily true for the classic BMI definition of \"overweight\". Within the \"ov... |
[
"Is it fair to compare ingesting an amount of food emitting 100 Bq/kg of K-40 to the same amount of food emitting 100 Bq/kg of Cs-137, I-131 or Sr-90 in terms of the biological effects of their decay?"
] | [
false
] | What I'm trying to ask: is each Bq the same as each Sv being the same (a weighted dose), regardless of their source? Is a Bq of K-40 as "dangerous" as a Bq of any other radioactive isotope. If not, how are the "dangers" of each source of radiation calculated and how do scientists know which isotopes are present in a sample and in which distribution. Sorry if this is gibberish, I probably have a lot of misconceptions on the subject. | [
"No. Different elements will have an affinity for different parts of the body. They also have different half-lives and decay energy. But perhaps most importantly, they all have different ",
" half-lives, which is the amount of time they stay in the body.",
"This is taken into account in radiation protection ... | [
"But once we convert the ingested amount to effective dose (or committed dose), then the \"danger\" per Sv will be equivalent. 100 mSv of internal exposure from K-40 is equivalent to 100 mSv of internal exposure from Cs-137.",
"Is there an easy way to do this conversion? I want to be able to say: \"ingesting an x... | [
"The annual limits are set at 20 mSv, so you can back-calculate from there. ",
"ex: 10",
" Bq Cs-137 per 20 mSv, so 0.02 microSv per Bq Cs-137."
] |
[
"Frost on car windows"
] | [
false
] | I've always wondered why this is. Why does the frost ice over my windscreen and side windows but not those that are nearest a wall? Can anyone help with this? | [
"One of my professors actually had to explain this phenomenon in his doctoral dissertation. Here's how he explained it: ",
"Basically, it has to do with what are called \"view factors\" and black body radiation. All object radiate some of their heat as electromagnetic radiation and this radiation depends on tempe... | [
"An explanation that doesn't require \"seeing:\"",
"The car emits radiative heat in all directions, as do all objects. The wall emits radiative heat as well, which counteracts the heat radiation from the car towards the wall. The wall and the car trade heat all night, while the car additionally radiates heat into... | [
"I own a carport and so far (-20° Celcius) no frost on the windshield."
] |
[
"What is the origin of the word \"moment\" in physics? [x-post from r/AskReddit/]"
] | [
false
] | The word "moment" in mechanics roughly means how a quantity acts about a given point. For example: "moment of force" (usually just "moment")---how a force acts about a pivot point, "moment of inertia"---how a body's mass is distributed about its center of mass, "moment of momentum" (usually just "angular momentum")---the linear momentum measured relative to a specified point. After much searching, the closest I've come to finding an origin is from the OED: "moment of a balance" n. [after post-classical Latin momentum staterae small weight or counterweight (Vulgate, corresponding to Hellenistic Greek ῥοπή small weight or counterweight (Septuagint); the Hebrew text has šaḥaq dust), misinterpreted in glosses (8th cent. or earlier) as denoting the tongue of a balance] the tongue of a balance. Obs. Any ideas? | [
"I came across this explanation in my search, but I don't quite find it satisfying---partly because we already use momentum to mean something completely different. Also, the use of moment always suggests how something acts (or moves) relative to a given point; I'm curious how \"to move\" became \"to move about a gi... | [
"A moment is really caused by abstractly moving a force to a new location and replacing it with a force and a moment. That is, a force of 1 N that is 1 m away is equivalent to a force applying 1 N and a moment (a moved force) of 1 Nm here."
] | [
"Just to clarify: I don't think that knowing the etymology of the word moment (for this context) will help me understand the physical concept any better (this isn't actually a problem). I'm just really curious how this word came to be used this way (either by logic or historical accident or some other rationale)."
... |
[
"How close are we to Digital Immortality? What research is being done on this front?"
] | [
false
] | I was reading some articles; first on our radio bubble, then on our attempts to contact life, then on artificial intelligence, then on mind upload... (the old Wikipedia link trail) and I couldn't help but fantasize about a future in my lifetime where anyone with enough money can have their mind digitized and preserved. Is this at all feasible in the near future? How would such a process exist? That is, would we be able to interact with our digital mind? Would it be able to control our body given the proper control systems? Given advances in tissue regeneration and lab-grown organs, could we possibly live forever with a digital mind? I know a lot of this seems like science fiction, but is it really? | [
"I think right now it's completely science fiction. Despite popular comparisons, our brains do not work like computers, and our brains are not digital. Right now we understand relatively little about how our brain creates the mind, and thinking about how you would encode a mind into digital logic seems pretty far o... | [
"We've learned a lot in the last 20 years of research, but there is SO MUCH MORE to figure out that to me the idea that we can completely understand the brain within our lifetimes seems a little difficult. The idea of completely mapping the brain is a little farfetched right now- it's just too complex to really eve... | [
"That's kind of what we mean by mapping- tracking all the connections neurons are making to each other and such. If you can simulate the entire brain completely, then there would be no issue (although you still have to map all the neurons if you are going to encode it in silico). But right now the pure amount of co... |
[
"Does seawater become denser as you get deeper? Is this change in density independent of the temperature change?"
] | [
false
] | [deleted] | [
"Another submariner here. In the real world the density of ocean water at different depths can vary greatly but mostly due to reasons other than depth. Water temperature and salinity are what would cause most of the density differences. "
] | [
"If I had a 1000 meter tall column of water (or any fluid), all at the same temperature, physical conditions, with only pressure changing, would the fluid become denser as I got to the bottom of the column?",
"Yes it would. Water has a low compressibility, but it is compressible, so density would increase with pr... | [
"Because their internal pressure is the same as the pressure of the water outside.",
"In physical terms, pressure doesn't do much, it's pressure differentials that hurt. If you were to tie a chunk of steak to a heavy weight and drop it off the side of your boat over the deepest spot in the ocean, nothing much wou... |
[
"Is it possible for a person to change angular momentum while in a vacuum?"
] | [
false
] | I have been wondering if this was possible after seeing the movie . If I were in low earth orbit, would I be able to flail my arms/legs around and be able to start spinning? | [
"Here's the answer you're looking for straight from the ISS. They even demo it for you. ",
"http://youtu.be/VJcno_XL4RU"
] | [
"Not unless you exert a torque on something else, e.g. by throwing something or expelling gas with thrusters. Though tidal gravity forces (the difference between the strength of gravity on one side of your body and the gravity on the other side) will exert torque, the effect is extremely small for something as smal... | [
"I can't intuitively think of a way to emulate the effect of the cat righting reflex, but I imagine something like it can be done.",
"Hold your arms out at right angles to your body but your legs together and in line with your torso. Twist and hold the lower half of your body with respect to the upper half. Then ... |
[
"What would happen if you a popped a balloon full of air in space?"
] | [
false
] | Assuming that it's possible for a balloon full of air to exist in space. | [
"Nothing too special would happen. Balloons can exist in space if the material is tough enough (hey, space shuttles are basically balloons; big containers full of air!). ",
"A standard, everyday party balloon would probably just expand and pop on its own without you needing to prick it with a needle. But other th... | [
"if the balloon was strong enough, it could last in space.",
"popping it would let the air escape, and it would then dissipate very quickly"
] | [
"This would fall under the topic of rarefied gas dynamics... which I am not an expert in. I have a friend who took a gas dynamics qualifying exam who said that the MIT fluid dynamics film on rarefied gas dynamics was really good. The source is ",
"here",
".",
"My understanding on what happens is you get a s... |
[
"Why do we know that Pi and E are transcendental numbers, but we aren't sure if Pi^pi or e^e are transcendental or algebraic?"
] | [
false
] | [deleted] | [
"The ",
"Lindemann-Weierstrass theorem",
" has as a corollary that, for any nonzero algebraic number z (which can be complex), e",
" is transcendental. In the reverse direction, this also shows that for any algebraic number z other than 0 and 1, log(z) is also transcendental (otherwise log(z) must be algebrai... | [
"/u/nijiiro",
"'s answer gives specific reasons why we know that π and e are transcendental. ",
"More generally, proving that a number is transcendental is really hard. You have to show that it can't be the root of ",
" polynomial with rational coefficients. Since there are a lot of polynomials, this sort of ... | [
"/u/nijiiro",
" gives a nice answer. I just wanted to take the opportunity to plug a similar fact which is easy to prove and a bit surprising. It is unknown whether e+pi or e*pi are rational or irrational. However, we do know that if one of them is rational, the other must be irrational. How? Consider the polynom... |
[
"AskScience AMA Series: I'm Nestor Espinoza, and I study exoplanets with the James Webb Space Telescope. AMA!"
] | [
false
] | I'm an Assistant Astronomer at the Space Telescope Science Institute (STScI) and an Associate Research Scientist at Johns Hopkins University. Here, I lead teams that focus on optimizing the scientific output from the JWST mission, with a particular focus on exoplanet atmospheric characterization, as well as teams focused on developing cutting-edge science for this exciting field of research using both ground and space-based facilities. I participated on the team that produced the first images and data for JWST (the Early Release Observations ---- EROs) --- and led the analysis that produced the first exoplanet spectrum (of many to come!) that was shown to the public of the exoplanet WASP-96b. I'm also part of several teams working right now on producing the very first scientific results on exoplanet atmospheres with JWST, which range on exciting new science from highly irradiated, gas giant exoplanets all the way to the very first observations with JWST of the small set of terrestial planets orbiting the TRAPPIST-1 star. I was recently featured as one of the experts in NOVA's documentary film, Ultimate Space Telescope, about the engineering behind the JWST. You can watch it here: Ask me anything about: Before joining STScI, I was a Bernoulli Postdoctoral Fellow at the Max-Planck Institute for Astronomy in Heidelberg, Germany. In 2018, I was selected as the recipient of one of the prestigious IAU-Gruber fellowships by the International Astronomical Union (IAU) for my work on the field. I did both my undergrad (2012) and PhD (2017) at the Pontificia Universidad Católica de Chile, in Santiago, Chile, where I was born and raised. I'll be on at 3pm ET (19 UT), AMA! Username: | [
"Great question ",
"u/Segesaurous",
" --- I'm just jumping from my chair right now just thinking about it :-). ",
"I think any carbon or oxygen molecule in a terrestrial exoplanet will make me jump out of my chair in excitement!"
] | [
"Thanks for this question! All my exoplanet dreams are layered, here's a breakdown --- top is the ones I believe will happen soon-ish (next few to tens of years), last ones might vary depending on how we do in the firsts: "
] | [
"How does searching for exoplanets with the James Webb telescope differ from the Hubble telescope?"
] |
[
"How much bleach could the average man drink before he died?"
] | [
false
] | [deleted] | [
"By \"bleach\" I assume you mean common household bleach, and not pure sodium hypochlorite. Household bleach is diluted down to about 5%. ",
"First off bleach isn't really a poison, it oxidizes cells, like burning, but without fire. ",
"Just breathing in the vapor from pure bleach would likely kill you before ... | [
"I would say yes, one or two gulps."
] | [
"So, you're saying maybe one or two gulps?"
] |
[
"Is the universe flat and infinite? How was it \"the size of a tennis ball\" if it is infinite?"
] | [
false
] | How are the first epochs of the universe comparable to finite diameters? For example, "x seconds after the big bang, the universe was the size of a tennis ball" It seems like a poor metaphor for lay people, and it just confuses me. How does the universe go from infinitesimal to infinite in spatial expanse? | [
"For example, \"x seconds after the big bang, the universe was the size of a tennis ball\"",
"They mean the ",
" Universe, which right now has a radius of 46 billion light years. If the total Universe is infinite, it always has been infinite at any x seconds after the big bang, where x is any positive number."
... | [
"A point of clarification: i think that these kinds of statements are usually referring to the scale factor, a_0, which is the size of the observable ",
". ",
"So the 'size of a tennis ball' remark should be taken to mean that what is ",
" our observable universe occupied a region of space the size of a tenn... | [
"I'm not enough of an expert in GR or topology to say whether or not a mobius-like flat geometry is possible, but I've never heard of it.",
"You can construct a flat Möbius strip in the same way that you construct a flat cylinder or a torus; take a strip-like subset of ",
" and identify the edges. For the Möbiu... |
[
"Are steroid alternatives any good?"
] | [
false
] | null | [
"We do not give medical advice on this sub. Please speak to your doctor."
] | [
"Not a problem, they have a pretty wide definition of what constitutes medical advice on this sub, and I myself have been censured for what I thought was an innocent remark. "
] | [
"Sorry, I wasn't necessarily looking for medical advice, more an insight as to whether or not steroid alternatives work."
] |
[
"What is the cause of excess protein in urine if a person has a protein deficient diet?"
] | [
false
] | In a pathology text I read a question that asked about a patient that had a distended belly, edema in the legs, low blood protein, but excess protein in the urine. The text stated it was caused by a lack of protein in the diet. How is it that a person who is not consuming enough protein ends up excreting excess amounts in their urine? | [
"Proteinuria is not a normal symptom of kwashiorkor (dietary protein deficiency), although minor glomerular changes are observed. It would make a lot more sense if the proteinuria were causing the hypoproteinemia, not the other way around.",
"http://books.google.com/books?id=bw7esE2kfwUC&pg=PA509&lpg=PA509&dq=kwa... | [
"The deficiency in protein might cause the body to produce more protein to be digested from its own sources, as the digestive enzymes produced endogenously start to digest the bodies own proteins leading to increased excretion of the proteins in urine. Fasting issues along with protein deficiency could lead to this... | [
"That was my logical conclusion as well, but I was unsure if I were missing something.",
"Thanks!"
] |
[
"What class of numbers are renormalization group constants?"
] | [
false
] | In mathematics and physics, there are constants that can only be determined through methods like renormalization group (roughly speaking, zooming in, squinting, analyzing, zooming in again, etc) or Monte Carlo. An example is the average size of a self-avoiding random walk as a function of length, the physical manifestation of which is the size of a blob formed by a polymer. A simple estimate puts this at 0.6 (so the a self avoiding walk is bigger than the regular random walk of L but renormalization group and Monte Carlo put it at around 0.588. Experiments on polymers put it close to this, but I'm more interested in the mathematical self-avoiding walk and things like that. I was wondering what type of numbers these constants are. If they haven't been written down as roots of a polynomial I guess that makes them transcendental, but has there transcendentality been proved? If they cannot be precisely calculated (only converged upon), does that make them uncomputable? Is there a class of number than can be known numerically but not written in closed form? | [
"They're definitely not uncomputable; the fact that we can approximate them arbitrarily close means that they ",
" computable! Similarly, if they are transcendental, i'd guess that their transcendentality hasn't been proven, simply because it's incredibly hard to prove numbers are transcendental. For example, we ... | [
"A number x is algebraic if there is some polynomial p with integer coefficients such that p(x) = 0. Transcendental numbers are not algebraic (and therefore necessarily irrational, otherwise they'd be roots of p(x) = b*x-a)."
] | [
"Is there a class of number than can be known numerically but not written in closed form?",
"Of course! We have a finite number of symbols (be they numbers or operators) and an uncountable number of real numbers - you can see where this is going. So there are actually infinitely many numbers that don't have a clo... |
[
"Does an increase in blood glucose necessarily mean there is going to be an increase in Insulin?"
] | [
false
] | I know about how Insulin regulates glucose, but does a small increase in blood glucose mean that the body is going to release more insulin or can the glucose levels lower through a different mechanism? | [
"In human biology no process is absolute, and the pancreas continually secretes varying levels of insulin. Blood-glucose is not the only stimulus for insulin release either.",
"However, in a hypothetical system where glucose is the only circulating ligand and insulin secretion is either 'on' or 'off' (no backgrou... | [
"Every time you eat there's an increase in glucose levels, which makes the pancreas produce insulin. No matter how small your meal or snack is. \nAnd yes, to lower glucose levels the only mechanism the body has is the insulin release. \nHowever, when your glucose levels are too low, your pancreas produces glucagon,... | [
"When you consume carbohydrates, your blood glucose levels will rise, assuming the carbohydrates are absorbed. The glucose in your blood causes the insulin in your beta cells to be release. It enters the cell through an insulin-independent transporter GLUT2. Once inside the cell, the production of energy from the g... |
[
"Why do I experience morning nausea during periods of depression?"
] | [
false
] | null | [
"We can't really comment on isolated incidents / personal anecdotes."
] | [
"Thanks, and I appreciate the difficulty of answering a vague question. ",
"It seems pretty common, from what I can see. However no where I can find explain why, just that it does occur. "
] | [
"You could try a more general phrasing like: why is morning nausea a symptom of depression? "
] |
[
"Why can't capacitors work like batteries?"
] | [
false
] | It seems they have this special property that only allows them to discharge quickly. Several years ago, scientsist were interested in this application, but the interest has seemed to died off. Why? | [
"Capacitors don't have the ",
"energy density",
" of batteries. So they are heavier and bulkier than batteries that can do an equivalent amount of work. Chemical bonds are marvelously good at storing energy at high density that is easily recovered and transportable (gasoline, batteries, mars bars, etc)."
] | [
"Interest has not died off;",
"http://www.physorg.com/news/2011-11-carbon-foam-key-ingredient-battery.html"
] | [
"Another issue is that a capacitor's voltage is dependent on the charge of the capacitor while a battery maintains a constant voltage over most of its lifetime. Many electronics require constant voltages. "
] |
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