title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"What is the hottest temperature you can feel, before the heat receptors stop feeling the pain of higher temperature?"
] | [
false
] | [deleted] | [
"The warm thermoreceptors on your skin can feel up to 50 degrees Celsius; it really stops around 45 degrees Celsius for most people though. But you should know that just because the thermoreceptors won't sense temperature above this threshold, doesn't mean they won't sense pain. Your nociceptors will work far beyon... | [
"thank you"
] | [
"This question may be more complicated than you think. Heat isn't a tangible thing you can touch or feel. Molecules move around and give energy to each other. This means that you can't just put your hands into a box at 9000 f and feel it. You'll only feel your hand raise in temperature until it hits auto ignition (... |
[
"Would gravity propagate at v<c when passing through a mass?"
] | [
false
] | Would we expect gravity to propagate at v<c in some sort of medium, analogously to how photons do this in a dielectric? Might the speed of gravity through a mass (just for instance) be less than c? | [
"First, photons still travel at c inside of materials. The aggregate phenomenon we call ",
" gets slowed down due to interactions, but the individual photons are still rocking along at c.",
"As for gravity, it's hard to say. The general theory of relativity is a continuum theory, and if you treat the material a... | [
"Yes, for all intents and purposes, the speed of light near massive, gravitating objects is less than c. This leads to the phenomenon of ",
"gravitational lensing",
".",
"The reason why the effective speed of light is less than c is that time runs more slowly in the presence of strong gravitational fields, a... | [
"Thanks for your answer! I was thinking less of the well-known warping of spacetime, than of something like gravitons interacting with nuclei/electrons in the mass. It may well be the possible quantum gravity effects."
] |
[
"FAQ Friday - How do you define \"species\"? Why can some species still hybridize?"
] | [
false
] | This week on we're here to answer your questions about species definitions! Have you ever wondered why two species are still considered separate, or one species hasn't been split into two? Darwin himself spent a great deal of time what a species is: No one definition (of species) has as yet satisfied all naturalists; y... | [
"I think the important thing to remember about species is that they are concepts. Species are ideas we impose on nature for our convenience and utility. ",
"Individual organisms are real entities, but species are a set of rules that guide our language and understanding of a collective grouping's behavior over tim... | [
"Just to add on, because this is pretty clear cut.",
"One thing I keep in mind with species is that it's a utility word.",
"A utility word is something I use to describe words that have no set-in-stone definitions, but are defined by the context. Which makes these words, in my opinion, more useful across disci... | [
"For sexually reproducing organisms, species is generally defined as being able to breed (despite the flaws of this definition). Is there a similarly general definition for asexual organisms?"
] |
[
"Do our brains process faces differently as we age?"
] | [
false
] | For example, a five year old looks at a picture of the face of a ten year old and thinks they look old and mature, whereas if the child looks at that same picture ten years later, he'll probably think the ten year old looks childish. Can this be explained in the brain? | [
"Yes, they do. To reiterate a few other comments, there's a part of the brain called the fusiform face area (FFA) that becomes more active when we're viewing a face. ",
"Here's a review article",
" about how this part of the brain changes as we grow up. It's from 2008, which is relatively early days of studying... | [
"Yes, various aspects of face processing do change. Face recognition memory declines with age, but more so for images of young faces than old faces (",
"Lamont, Stewart-Williams, and Podd 2005",
"; see also ",
"Bartlett and Fulton 1991",
" <- pdf!; ",
"Crook and Larabee 1992",
"). These effects may part... | [
"Hi, I'm trying to read about anything related to how your brain changes as you age, at like 50 years plus. Do you know of anythong worth reading?"
] |
[
"How do we actually know the earth is 4,5 billion years old?"
] | [
false
] | I've always just assumed this is true because people smarter than me said so. Lately I've been wondering what the methods are that they use to determine the age of the earth. Note I'm not looking for a two word explanation like "carbon dating". How does it actually work, is it not effected by different environments and... | [
"The primary method used to measure the age of the earth is ",
"radiometric dating",
", of which radiocarbon dating is one method, but radiocarbon is not in anyway relevant for the age of the Earth because the half-life of C-14 is ",
" too short (radiocarbon can reliably date things back to ~50,000-60,000 yea... | [
"I remember reading about a certain crystal structure that incorporates uranium but not lead.",
"So a trapped amount of uranium has to be \"pure\" to be in the sample, essentially caged. Therefore, and lead is from decay of that particular uranium. Aging of the crystal is thus possible. ",
"Do I have that r... | [
"That is (generally) true for some crystals, specifically zircon. I.e., uranium can easily replace for zirconium in the crystal lattice, but generally lead is excluded during formation, so any lead present can usually be safely assumed to come from decay of uranium in the zircon. Because there are two isotopes of u... |
[
"In a place like \"Gatineau Park\" in Eastern Quebec, how were all those lakes formed? Glaciers, tectonic movement, etc...? (pic/map included inside)"
] | [
false
] | You can see that there are dozens of little lakes and about half a dozen large lakes. It is like this all over Quebec. Why? My friend says it is all from glaciers but I do not really understand how they would have formed all these lakes. | [
"Kettle lakes",
" form when glaciers retreat and large ice blocks calve off the front of the glacier and become buried, then melt and form a lake.",
"However, the ",
"Laurentide ice sheet",
", which covered the region during the last glaciation, would have scraped and gouged the underlying bedrock, also for... | [
"Fixed link: ",
"http://en.wikipedia.org/wiki/Kettle_%28landform%29"
] | [
"Eastern Canada, Western Québec. ",
"As Wrathchilde said: most of the lakes in Canada, including the Great Lakes and the Saint-Lawrence are a result of the melting of the Laurentide ice sheet and the draining of the subsequent ",
"Champlain Sea",
".",
"The only credential I have is a Québec pre-universitary... |
[
"How does host selection work for different species of parasitic wasps?"
] | [
false
] | There are thousands of species of parasitic wasps, and they have a diverse range of hosts for which they lay their eggs in, such as caterpillars, spiders, aphids, etc. However, could, for instance, a tarantula hawk wasp be able to lay eggs in a caterpillar, and just prefers targeting spiders, or can it only lay eggs in... | [
"Hi! ",
"Parasitoids tend to be very specific to their hosts (even if they attack different species within a family) as they need to overcome the defense mechanisms that the host has to defend themselves from the parasitoid. ",
"Some caterpillars create melatonin bubbles around wasps eggs, others have white glo... | [
"Hell yeah! Some of these viruses can can only replicate inside the reproductive tract of female wasps, and as mentioned before ",
"their primary function is to protect the wasp offspring from the immune defenses of the host",
" ",
"And not only symbiotic relationships! Plants also releases what’s called ‘",
... | [
"and some wasps use different mechanisms such as venom, paralyzers or even polydnaviruses",
"Hang on, so these parasitic wasps can have a symbiotic relationship with viruses that help them parasitise other insects?!"
] |
[
"Is there an evolutionary advantage to passing out from pain or shock?"
] | [
false
] | Seems like it would just make it easier for predators to eat you. | [
"I think it depends on your terms.\nShock refers to a state of inadequate delivery of oxygen to the tissues. The brain is highly dependant on an uninterrupted oxygen supply, so in a state of shock the brain may cease to function and you therefore lose consciousness. This is not an evolutionary adaption but rather a... | [
"The evolutionary advantage to passing out is because of oxygen delivery to the brain. Your body will do ANYTHING to keep your brain alive, because without it, there is no point in keeping the rest alive.",
"When your blood pressure is too low to adequately deliver oxygen/glucose to the brain, you will pass out.... | [
"Which begs another ponder - if the brain is our key point, why did evolutionary mutations put it way up at the top, admittedly the hardest point to reach in terms of gravity? Is it because the PSI in our blood stream makes it fairly nominal for blood flow to reach it?",
"I'm reminded of the time I had a CAT ... |
[
"On an evolutionary scale, what happens to organisms when the environmental pressure is removed?"
] | [
false
] | Have there been any experiments done that test what happens to organisms that do not experience competition, environmental pressure etc. What happens when the natural selection part of evolution disappears? Do the organisms still tend to create variation or do they rather remain unchanged? | [
"The other answers here are effectively talking about what happens in populations that are under stabilizing selection to maintain the same body form over long periods of evolutionary time. This is quite different from what would happen if all selection were actually removed.",
"If there is truly no selection, th... | [
"That's really interesting: when external pressure is removed, given enough time, genetic drift will lead to the population losing genetic variation. It's such a bizarre thought: if I understand correctly, in these circumstances the individual organisms would effectively become genetic clones, wouldn't they?"
] | [
"when external pressure is removed, given enough time, genetic drift will lead to the population losing genetic variation. It's such a bizarre thought: if I understand correctly, in these circumstances the individual organisms would effectively become genetic clones, wouldn't they?",
"This would happen only in th... |
[
"Can someone explain the IUPAC nomenclature of caffeine?"
] | [
false
] | I came across it while looking at IUPAC nomenclature of organic compounds--planning on taking org chem in college, figured I'd get a start now--and most of it isn't confusing, except for the parts in bold. -1,3,7-trimethyl- -purine-2,6-dione First, why are 3 and 7 listed as hydro- groups when there are methyl groups bo... | [
"To be honest I am not sure how that is supposed to make sense. Seems easier to make to just add a suffix indicating single bonds.",
"The thinking is that aromatic rings are a good \"basis\" for naming things, so different states of saturation should be based off it. Like it or not, aromaticity does confer the mo... | [
"They are used to indicate the molecule is missing double bonds compared to the base component purine.",
"1H stands for the 1H form of ",
"purine",
", the where the atom numbered 1 does not have a double bond and is instead bonded to a hydrogen. 3,7-dihydro indicates the 3 and 7 positions have hydrogens, whic... | [
"Thanks, though! That pretty much cleared it up. I had looked into the different H-es of purine but wasn't sure how their nomenclature was derived. So uh, thanks. Again."
] |
[
"Is it possible to achieve geostationary orbit at lower altitudes?"
] | [
false
] | Hi there, I'm a little confused as to different orbiting velocities of our current satellites. The ISS at an altitude of ~430km orbits with a speed of ~27600km/hr. For geostationary satellites, I've read that the must achieve an altitude of ~35,786 kilometres in order to maintain that orbit. Why is this? Why couldn't y... | [
"Is it possible to achieve geostationary orbit at lower altitudes?",
"No. This is a direct result of ",
"Kepler's 3rd law of planetary motion",
" which says that the square of the oribital period is proportional to the cube of the radius of the orbit. For geostationary orbit, the period must be approximately ... | [
"For a ",
" orbit, you need to be going at a fixed speed, and that speed decreases as you get further from the Earth.",
"If you're going a little slower or a little faster, then you end up in an elliptical orbit instead. By going a little bit too slow, you fall towards the Earth a little in your orbit. But this... | [
"I was thinking about this too; that NASA could just perform a longer-than-average burn of the spacecraft to bring the satellite to greater than regular orbital speed.",
"They could, but it would change their orbit. So the only way would be to do that, ",
" thrust to counteract that at the same time. But \"orbi... |
[
"Are there other signals similar to the \"WOW!\" signal? Was that the closest we ever gotten to find real extraterrestrial life?"
] | [
false
] | Just curious if the scientific community has really been any closer on finding extraterrestrial signals than this one or the ? These sort of discoveries really excites me. Would it be possible to track again these signals? Are there any more of those? | [
"The short answer: yes.\nIf you read (or listen to the audio book) Pale Blue Dot (1994) by Carl Sagan, he discusses 8 events that have occurred over the last 20 odd years (as of 1994) that meet ALL criteria necessary to be considered to be of extra-terrestrial origin except one which is repeat-ability. ",
"None o... | [
"I know of no other signal like that in the extraterrestrial life community, but puzzling signals like that are pretty common across fields. Another famous one is the Valentine's Day monopole. Stanford professor Blas Cabrera built a magnetic monopole detector and switched it on in the basement of the Varian physi... | [
"This sort of \"debunking\" is absurd to the highest degree. It makes a lot of very uninformed assumptions. ",
"A signal ",
" to broadcast a simple beacon throughout the galaxy would not use any data compression because it wouldn't really be transmitting anything. A beacon signal would be something like a pulse... |
[
"What are the benefits of gravitational slingshotting?"
] | [
false
] | OK, I'm just an engineer. As I understand 'conservative systems' like gravity you get back what you put in. So you slingshot a space probe or whatever past a gravitational source and get it to accelerate wildly. But doesn't it slow down while leaving that source exactly in reverse to how it sped up while approaching th... | [
"From the reference frame of the planet that is doing the slingshotting, the spacecraft does leave at the same speed at which it approached.",
"However, if the ",
" that the spacecraft leaves is more in the direction that the planet is moving than the direction from which the spacecraft approached, then in the ... | [
"Would it be accurate to compare it to a perfect elastic collision of throwing a tennis ball at a moving basketball?"
] | [
"Yes, that's pretty accurate, but of course with a much lager mass ratio. "
] |
[
"What am I getting wrong in my understanding of the twin paradox?"
] | [
false
] | Please bear with me on this. I'm going to explain my understanding of the question first, then pose my question. Responses should take two forms. One is to correct misunderstanding inherent to my question, and the other is to answer my question directly. So I know that there are 2 fundamental theorems to special relati... | [
"First of all, there is no negative time dilation. Time always moves slower for the moving twin in the frame of the twin at rest. The time dilation for someone moving toward you or away from you is the same, it only depends on the magnitude of the velocity and not on the direction.",
"The same thing is true for l... | [
"The biggest fundamental thing I see missing from your understanding is length contraction. You say that these two rings are 1km apart, but observers A and B actually disagree on the distance between the rings. If the traveling observer thinks their 1km apart, the earth observer will actually see them as much close... | [
"This is resolved, as any explanation you can find with Google will tell you, by realizing that the situation does not adhere to the setting of special relativity. In special relativity, we can only consider inertial frames that move at constant velocity with respect to each other. When twin B turns around to retur... |
[
"Why is Rh negative blood so common in the geographic west?"
] | [
false
] | It consistently increases the further west you go in Eurasia. It is nearly nonexistent in east Asia, 4% in Bangladesh, 9% in Punjab, 12% in Russia, and 15% for Europe as a whole. In Spain, it reaches about 20%. Among the Basque, it tests at ~30%. In Beni Boussaid in the Atlas mountains (Algeria), it tests at 21%, whic... | [
"Genetic drift explains it. If you have an autosomal recessive gene randomly distributed in a population, you can either wean/winnow it down or amplify it up by clustering the population and propagating it.",
"See this analogy using 'marbles in a jar' to illustrate how a few initial minor changes in a population ... | [
"Sexual selection cannot plays role in something that is invisible to us. Although in Japan, blood type is a part of a dating profile because of a (mistaken) belief that it is linked with personality, like a bloody zodiac!",
"So Japan maybe has sexual selection by blood type?"
] | [
"There is a theory that being a heterozygous carrier of the rh negative mutation (which is technically just a deletion of the RhD gene) is protective against the lowered reaction time caused by ",
" infection. It makes sense that there is some kind of selective pressure sustaining this mutation, as in homozygous ... |
[
"How does a transistor actually *work*? What are the electric physics behind it, and how does this assemble into logic gates?"
] | [
false
] | I've been looking up this issue, and all I've found is that gates just , but never they operate at the physical level, and neither have I seen such a thing (in common English) for transistors. | [
"By \"common English\" I assume you mean a simplified layman explanation. ",
"Computers use a specific type of transistor called a metal oxide field effect transistor, or MOSFET. There are other types of transistors too, such as BJT, which I honestly think would be harder to explain in common English. I can kinda... | [
"I'm only qualified to answer the second part of your question:",
"how does this assemble into logic gates?",
"A transistor varies the resistance between collector and emitter based on the voltage that you apply between the base and the emitter. Computer circuits work just with two states: voltage or no voltage... | [
"So, if I read this right: Applying electricity to the insulation to \"open it up\", so to speak, for the flow to go through?"
] |
[
"Could additives (i.e. cayenne pepper) be added to prescription pain killers to curb abuse?"
] | [
false
] | [deleted] | [
"Right, because nobody ever has chronic pain until they turn 18."
] | [
"Right, because nobody ever has chronic pain until they turn 18."
] | [
"I remember speaking to someone who developed pharmaceuticals, and certain compounds such as hormones are absorbed best through the mucus membranes. Perhaps a pill could contain a hormone that would cause withdrawal symptoms or another discomforting effect that would happen when snorted. But when ingested, that hor... |
[
"Why don't magnets stick to some metals (e.g., aluminum)?"
] | [
false
] | null | [
"It's related to my work, but I'll put the bulk of magnetism in layman's terms and avoid my actual work.",
"First we notice that permanent magnets (which is probably what you're referring to when you say magnet, such as the magnet you'd put on your refrigerator) will stick to other permanent magnets. If you take ... | [
"It would be helpful for someone to clear up assumptions I made if necessary, and to possibly expand on any sections. I didn't really focus on filling atomic orbitals, Pauli exclusion, etc., but I'm not sure whether it's necessary or not.",
"I have a hard time explaining ferromagnetism at this level, and ",
" E... | [
"Nice explanation! I'm a materials scientist and my specialty is not magnets, but I thought I'd chip in a bit.",
"Your final point sounds like magnets only stick to crystalline objects, which I want to clarify is not always true. ",
"Here",
" is a video of liquid oxygen, a decidedly non-crystalline material, ... |
[
"Why do colors affect this optical illusion?"
] | [
false
] | I was messing around with this picture in photoshop and noticed when I changed the hue/saturation the illusion became nonexistent. Why is that? What is going on to cause the illusion in the first place? | [
"Here's a modified one that does: ",
"http://i.imgur.com/Ejcs4.jpg",
"Hypothesis time! I had an inkling that ",
"complimentary colors",
" were required for maximum effect. Since blue is not a complimentary of red, the second doesn't work nearly as well.",
"From my brief experiment, it appears that is t... | [
"Here",
" is one I made using the same palette. "
] | [
"The receptors in your eyes get saturated, then when you look somewhere else there is a residual image which is the \"opposite\" color - opposite in the sense of how your eye percieves the color, not in some art sense. You can try this by staring at an image without moving your eyes for maybe a dozen seconds and th... |
[
"What stops a woman's antibodies from attacking and killing a newly developed fetus in the uterus?"
] | [
false
] | Are there certain cells that keep antibodies from attacking the fetus? Does it have to do with the placenta? | [
"The placenta is the main player here. It acts as a barrier for immune cells and has specialized characteristics to hide from a maternal immune response. Antibodies from the mother do pass the barrier though and serve an important protective role for the newborn which cannot effectively make its own high-powered a... | [
"It happens. It's called Fetal Hydrops. ",
"It has to do with if there is a molecule on the baby's blood cells that are not on the mother's blood cells (similar molecules to determining blood type, A, B, AB, O - it is the POSITVE or NEGATIVE). ",
"Scenario: If a FIRST baby has the POSITIVE molecule on their blo... | [
"Immune Tolerance in pregnancy"
] |
[
"How does the gas pump know when to stop pumping the gas? Does it use certain sensors or just stop at a certain amount of gallons?"
] | [
false
] | null | [
"Next time you get gas look closer at the nozzle, you'll notice it has two holes. One where the gas comes out and one were air is allowed to flow back in. When the gas fills your tank eventually it covers this hole, and a pressure valve releases closing the valve to the pump inside the handle. It's quite a neat des... | [
"Just to add, this is also part of the vapor recovery system keeping the amount of fuel vapors to an absolute minimum, so next time you fill up, don't top off your tank. It forces fuel up those holes and not only can it compromise the system, you end up paying for that little bit of fuel that's not going into the c... | [
"Vapor recovery is yet another system, independent of the auto shutoff. There is very much a KISS thing going on with the autoshutoff valve, adding another feature to it would weakaen that."
] |
[
"[Mathematics] What type of counting system do we use for time?"
] | [
false
] | A little googling tells me its a sexagesimal (base 60 counting system) which to me fits fine enough for seconds and minutes, but when you include <microseconds and hours and days and such it becomes more complicated. I would call it a hybrid counting system, base ten for the first digit, base 6 for the second digit, tw... | [
"Time is a ",
"Mixed Radix System",
"."
] | [
"I just had a 40 minute game of \"Follow The Definition Link\". Utterly delightful, and I am happy that I remember something from University at least."
] | [
"As another example, I think an argument could be made that computers use Unix time similarly, that is counting every second since Thursday, 1 January 1970. Representations in the gregorian calendar are calculated from there, but are not part of the system itself. If you wanted a time before 1970, you would simply ... |
[
"Why does the earth, as well as other planets, rotate?"
] | [
false
] | I dont believe this to be related to the earth's magnetic field interacting with its layered structure... but Why? | [
"Conservation of Angular Momentum. The current theory is that a large cloud of gas collects and begins to contract due to it's own gravity. If the particles have any lateral movement (almost impossible not to), a spin will develop. And much like a figure skater speeding up when they pull in their arms, the spin ... | [
"Those are ",
"tidally locked",
" planets, they do spin, but their spin rate is one rotation for every orbit, meaning that they have the same side facing toward the star at all times. It's not caused by impacts, it's just caused by the gradual tidal drag force on the planet's rotation which slows the spin until... | [
"Well when the planets were forming they were formed out of spinning clouds of dust and rocks. And since that cloud of dust was spinning around the the the proto planet when the planet was formed it would be spinning as well. Also another reason why planets spin are massive impacts. Part of the reason why the Earth... |
[
"A question involving lightning strikes."
] | [
false
] | [deleted] | [
"Let's assume that 100% of the energy of the bolt is transferred to thermal energy of the pool. In reality it will be much less.",
"According to Wikipedia, the energy of a lightning bolt is 500 MJ. The heat capacity of water is 4.18 J/(g K). An olympic sized pool has 2500 m",
" Water's density is about 1000 kg/... | [
"No, that has nothing to do with the calculation.",
"An olympic sized pool raised by 0.05 degrees stores the same amount of energy as 2.5 cubic metres raised 50 degrees.",
"You can use water to store electricity, either by heating it up as you suggested, by raising it and giving it gravitational potential, or b... | [
"Probably easier just to raise a lightning rod than to launch rockets."
] |
[
"Do animals have allergies to other animals or humans like humans do to dogs, cats, etc...?"
] | [
false
] | I know there can be food allergies for dogs to chicken, for example, but I'm talking more like being allergic to dandruff or saliva or something more along those lines. | [
"Yes, it is possible. ",
"The human or animal body can react to an allergen (a protein that causes an allergic reaction) that comes from basically anything. Some of these allergens, however, are more common to cause an allergic reaction among a population. ",
"For instance, it's is more common for humans to be ... | [
"Do not post anecdotes or personal theories on ",
"/r/AskScience",
". "
] | [
"Do not post anecdotes or personal theories on ",
"/r/AskScience",
". "
] |
[
"Is weight/fat loss effected by season? I.E. is it harder to loss fat in the winter than in the summer."
] | [
false
] | So my "personal trainer" that I just started using told me that losing fat in the winter is more difficult than in the summer because it's cold and your body will try to keep fat because of that. I was skeptical of this but didn't want to call him out to his face right then. So what is the actual science, if any, behin... | [
"Easier in winter because naturally our body is burning more calories to maintain our internal body temperature of 37 degrees.\nSo we are more likely to use more calories than we take in.\nHowever we often compensate for this in the winter by just eating more food."
] | [
"He said personal trainer. Unless he's training outside with his trainer (unlikely), the temperature comment is irrelevant. Not to mention nonsense. The caloric difference is negligible."
] | [
"Clarification: My personal trainer did say this, we are working out inside, not out, but with windows cracked so there is a slight temperature different between summer and winter in the gym. I think he was more referring to daily life of being out in the cold, to which I'm still skeptical.",
"I was just curious ... |
[
"Is it possible for an element with zero protons and zero electrons to exist/have existed?"
] | [
false
] | Similar to the element zero on the Mass Effect games. Is it possible for an element like that to exist and if so, how would it interact with other atoms and molecules? | [
"So neutrons only? The only bound nucleus containing only neutrons is just a single neutron. Any other nucleus with Z = 0 and A > 1 is unbound."
] | [
"Neutron stars have a complicated makeup as a function of depth; they're certainly not entirely made of neutrons. However a neutron star is not really a \"nucleus\" or an \"element\", although they are an interesting manifestation of nuclear matter."
] | [
"There's not really a way to answer \"why\" that's the case. The nature of the nucleon-nucleon interaction is such that the only bound state in a two-nucleon system is the lowest-energy isospin singlet. That's the ground state of the deuteron."
] |
[
"If me and someone else pointing guns and i shot him in the head, will he be able to squeeze the trigger due to the shock?"
] | [
false
] | null | [
"I've always wondered about this, it's relevant in so many movies when there's a standoff or hostage situation. How safe is it to shoot someone who is pointing a gun at a victim? When a character hesitates to shoot the criminal, are they worried about hitting the victim, or about not incapacitating their target qui... | [
"It's totally safe most of the time. How fast does sound travel? 812mph or close right? How fast will x bullet travel? The answer is almost always faster. That's right they never hear the bullet that hits their brain and shuts it down instantly. There are freak occurrences of course but thats what it would be. The ... | [
"A shot in the brains does not turn it off immediately. People can survive a shot to the brains. To \"turn of\" immediately you need to shoot to the neck (where head connects with neck, to severe the spinal cord).",
"EDIT: there are lots of bullets that travel at subsonic speeds. Although you are right on this pa... |
[
"If the velocity at the walls of a duct is zero in laminar flow, why does the liquid still move with the center?"
] | [
false
] | null | [
"Laminar flow can occur in either a rectangular or cylindrical pipe. The flow velocity is zero at the solid-liquid interfaces, but it's not zero anywhere else. It's maximal in the center of the pipe."
] | [
"Yes, but nearing the edge it’s a value that’s very close to zero and that begs the question of how is it flowing at the edges so much slower than at the center without the shape being a peak"
] | [
"The shape ",
" a peak. The velocity profile for laminar Poisseuille flow in a cylindrical pipe is parabolic."
] |
[
"I've started listening to classical music while I study and write papers now and it has been amazingly effective. more so than other types. is there a reason behind this? Is my brain more active when listening to it?"
] | [
false
] | null | [
"some people do need a background noise to help keep them concentrated at the intended task.* tends to help more with people with strong inner dialogues. ",
"why classical over other types? no lyrics.",
"*will look for source"
] | [
"Given how predictable and uniform most classical music is (at least pre-XX), it really might work as a background noise, yea.",
"And it bothers me that some people think classical music just makes your brain more active, or \"smarter\". There's nothing that special about it, it's just music."
] | [
"I do tend to have a fairly strong inner dialogue going. I actually asked some of my friends and i've gotten a lot of different responses. My friend who studied classical guitar for a while said it was too engaging for him to listen to. I think that it might just be the fact that I don't understand what the singers... |
[
"Do animals with tracking devices have more difficulties with normal behaviors (hunting, mating, etc.)?"
] | [
false
] | null | [
"Scientists do their level best to make tracking devices and tags as unobtrusive to the animals’ daily lives as possible, and for the most part they succeed. You still end up with the occasional case like the ornithologist who banded a couple birds with red leg bands that were apparently so sexy to females of the s... | [
"I'm pretty sure that those birds were delighted to discover their new found sexiness"
] | [
"“Under carefully controlled conditions, with environment and all variables well adjusted, the organism does as it well damn pleases”.",
"\nSuch as in this case where scientists set out to research avian behaviour and accidentally invented bird lingerie instead."
] |
[
"Can fish become \"overweight\" from eating too much? Do they generate mass like an overeating human would or does their body size just keep growing until a certain set point as they eat larger proportions?"
] | [
false
] | I thought of this while feeding my tropical tetra fish today. I can't say that I've ever seen a fat fish but then again I don't think I would know it if I saw it. I know there are are freshwater fish as well as tropical... do they differ on this topic? Any insight would be appreciated. | [
"I'm not a fish biologist (I'm a microbiologist!), but I did teach an intro bio course so I think I can provide a suitable answer. Fish are interesting and somewhat unusual amongst vertebrates in that their growth is ",
"indeterminate",
" (disclaimer: not true for ",
" fish). This means that as long as they d... | [
"There would be a point though when they ",
" hit a growth wall, right? Not because of a maximum size limit, but maybe because they can't physically consume enough food to allow for further growth?"
] | [
"It's absolutely true in that it depends on the environment and availability of food. As other people have mentioned, in a small space (eg: aquarium or pond) the fish will stop growing. However in a large enough environment (think large lake or ocean) there's no reason why they'd ever stop growing as long as there'... |
[
"What do neuroscientists think about IBM's blue brain project?"
] | [
false
] | I'm curious to know what actual neuroscientists think about , some of the claims they made in this seem really optimistic. From the FAQ on the site: Will consciousness emerge? We really do not know. If consciousness arises because of some critical mass of interactions, then it may be possible. But we really do not unde... | [
"I'm not sure I can answer your consciousness question - but I can tell you what I think of the blue brain project.",
"The trouble with projects of this type is that they never account for the neuroscience. In generating massive quantities of neuronal interactions, it's unlikely that it will resemble the brain. ... | [
"It's kind of rhetorical, I know it can't be answered. I'm more asking what actual neuroscientists think about the project and how it'll benefit their line of work in the long run. I'll put that in the OP."
] | [
"Oh, ok. Sorry. Im very interested in hearing their thoughts, too =) Didn't meen to bring your question of track."
] |
[
"How do certain medications that are supposed to reduce depression make someone feel more suicidal?"
] | [
false
] | [deleted] | [
"SSRIs are notorious for supposedly increasing suicidal ideation in the weeks before it starts working, but ",
"the evidence for this effect is weak",
".",
"A big problem with Selective Serotonin Reuptake Inhibitors is that no one knows how they really work. We do know that most people who benefit from SSRIs ... | [
"Do you have any papers on that? I'd love to read them."
] | [
"Do you have any papers on that? I'd love to read them."
] |
[
"If you had two plates, which had surfaces that were absolutly, 100% smooth, and you layed them on top of one another and managed to get all the air out that was between them, would it be possible to pull them apart?"
] | [
false
] | Say you have two square plates of any material. Both faces of the plates are impossibly smooth, as in they are absolutely flat. If you placed these two plates together face on face, and somehow managed to get 100% of the air out from between them, would they not be impossible to remove from each other? As far as my un... | [
"It would not be impossible to pull them apart. ",
"Best example would be a plunger of a perfectly smooth syring with abolutely no air left inside. You could still pull the plunger back, you would just be working against atmospheric pressure.",
"However, depending on the material the interfaces could become che... | [
"I think this is question about cold welding? What actually favors a cold weld? Flat interfaces. No contaminants. Get rid of air pockets, and you will have more contact points between the two interfaces. Clean off the oxidation, and it would be even better.",
"However, if I took, say, a rod of some metal and pull... | [
"Are you a professor? You sound like my physics professor. "
] |
[
"Is interstellar space CHOCK FULL of photons?"
] | [
false
] | I know there is the odd hydrogen atom diffused around the universe, in even the remotest, emptiest bits of interstellar space. But I know light is both a particle and a wave, and the particle is called a photon. Since, from any point in our galaxy, you can see billions of stars- does that imply that interstellar spac... | [
"Of course there's tons of photons everywhere. But most of them possess very, very little energy. Space isn't particularly bright when you're not nearby a star."
] | [
"Wait, so most of the photons in empty space are microwave frequencies? And the visible light from stars (which might even be enough to read by) are a small percentage of that? ",
"Wow."
] | [
"Oh, okay, so then everybody acknowledges that interstellar vacuum is a very active place, and only ",
" cold, empty, and boring.",
"I was afraid I was missing something. Thanks!"
] |
[
"What is the \"Overlapping Map Theorem,\" or whatever it's really called?"
] | [
false
] | I remember hearing about this math/geometry concept where if you were to take two maps of an identical place, even if they're different sizes, then lay one over the other, there will always be a point at which you can place a pin that it will be the same proportional coordinates. I can't find anything by searching "ove... | [
"That would be ",
"Brouwer's Fixed-point Theorem",
".",
"The full mathematical statement is a bit more comprehensive, but one of the consequences of it is that you can always overlay 2 maps and find a spot where you can prick a pin through both maps and hit the same location."
] | [
"Otherwise known as the \"You Are Here\" pin on shopping mall maps."
] | [
"Another consequence is that if you have a map of the place you're in, no matter how large the map or how small the place, there is a point on the map that's in the ",
" place it represents."
] |
[
"Do lasers become less powerful over distance in space?"
] | [
false
] | Just looking at the massive EVE battle, thinking about lasers as weapons, and I started wondering if there's any limit to the distance a laser could be used as a weapon or otherwise. Like, if we had an asteroid coming, could a laser be used to melt the ice and break it apart, and if-so, just how far could one go? Of co... | [
"All laser beams spread over distance due to ",
"diffraction",
". You can predict the amount of spreading by ",
"gaussian beam",
" analysis. ",
"The amount of spreading is less if the initial beam diameter is larger or if the wavelength is shorter."
] | [
"Is diffraction also what causes a decrease in the intensity of non-collimated light?"
] | [
"If light has not been collimated, there should be no diffraction. However, anything emitted isotopically should be subject to the inverse square law due to pure geometry"
] |
[
"Does the visual cortex in a congenitally blind person display any activity when they're prompted to imagine something?"
] | [
false
] | I'm really curious to know what goes on in a blind person's mind when they're asked to imagine something or reason through something with visual components. Because so much information is processed via the visual cortex in the non-blind population, Im hoping someone might be able to shed some light. | [
"I'm going to link you this paper here, titled ",
"Visual Imagery Without Visual Perception",
" that goes into great detail on this topic. It's an easy read, but page 179 and onwards are particularly pertinent to your query. ",
"In so many words, the researchers studied congenitally blind subjects via PET sca... | [
"For the human figures, even without having contact with other humans, they can have a physical model because they have their own body.",
"Small objects like the bucket and ball, they can have explored by touch.",
"The sailboat and palm tree they'd have to explore by touch, but a miniature is more likely.",
"... | [
"This is a fascinating study! It would be interesting if there is more research into visual perception ",
" (aphantasia). "
] |
[
"What are some problems or disadvantages of Thorium nuclear reactors?"
] | [
false
] | [deleted] | [
"A main one right now would be lack of experience in making them. Unlike U-235 which we have pretty much nailed down well, U-233 has been used very little, and there could be (and very likely will be) engineering or economical issues we would have to solve as they come up during development.",
"MSRs have a lot of... | [
"Well, it's not necessarily easy. Not from an engineering standpoint. The concentration of Uranium in seawater is really low, we are talking parts per billion. But due to the volume of the oceans, this is an enormous amount of Uranium, several orders of magnitude more than in the crust, and enough to power the Eart... | [
"Wait, how can Uranium be extracted from the ocean? I've never heard of this before."
] |
[
"What caused motion sickness?"
] | [
false
] | null | [
"here the main thing to know about is the -- 'VESTIBULAR SYSTEM' (this is merely a general explanation of the ASAP science video -- ",
"https://www.youtube.com/watch?v=0CP0VX9XFXU",
")",
"--"
] | [
"sense of movement and your sense of vision",
"Your ",
"sense of proprioception",
" plays a part, too."
] | [
"sense of movement and your sense of vision",
"Your ",
"sense of proprioception",
" plays a part, too."
] |
[
"Are there AC equivalents to transistors? What happens when you run a transistor backwards?"
] | [
false
] | null | [
"What do you mean by \"AC equivalent\"? And what do you mean by \"backwards\"?"
] | [
"I accidentally replied to you under top post and not as reply to this post, see my response above."
] | [
"I am software engineer so my conceptual understanding of a transistor is basically an AND gate with two inputs and one output... with a DC current I guess this makes sense but I have no idea what would happen if you tried to run one backwards with 1 input and two outputs... this made me think if I there was any co... |
[
"Where would the energy solar panels/wind turbines use go if not for electricity?"
] | [
false
] | null | [
"Hi TheTryingDutchman 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 t... | [
"'earth sciences'"
] | [
"Earth Sciences"
] |
[
"Does background radiation change at all?"
] | [
false
] | null | [
"It can. It changes based on your altitude, your location on Earth, etc. "
] | [
"Are the changes drastic?"
] | [
"I wouldn't say \"drastic\", but \"significant\", perhaps."
] |
[
"How was Faraday's constant determined experimentally?"
] | [
false
] | I am just wondering about the origin of the constant and how to recreate it. | [
"I was going to try to summarize the history, but found it all discussed with more detail than I would have been able to provide ",
"here",
" ."
] | [
"This is the most relevant paragraph I found to your wiki link.",
"The electric charge per ",
"mole",
") of electrons is a constant called the ",
"Faraday constant",
" and had been known since 1834 when ",
"Michael Faraday",
"published ",
"his works on electrolysis",
". In 1910, ",
"Robert Milli... | [
"Click the \"his works on electrolysis\" link."
] |
[
"How or why did blood types evolve? Is there any difference between them apart from accepting other types?"
] | [
false
] | I'm studying non Mendelian genetics in high school right now, and my teacher's explanation didn't satisfy me. I know how friendly this subbreddit is, but I want to say this anyway, this isn't a homework, just curious. | [
"Blood type comes from an assortment of different antigen markers that can be attached to the surface of red blood cells. You've probably heard of blood types 'A', 'AB', 'O', etc. but that's actually only one of many different blood groups, or categories, that go on to define blood type. We inherent these from both... | [
"I'll add to what others have discussed here.",
"There are way more than just A, B, and O bloodtypes - this is just one antigen 'group.'",
" There's also the Rh group, and at least 20-30 others. The reason you hear about A,B,O and Rh- and Rh+ the most is because these are (generally) the most important ones for... | [
"so blood types are like WPA keys."
] |
[
"everyone knows you can convert matter into energy with e=mc2, by is it possible to convert energy into matter?"
] | [
false
] | null | [
"That's what they do at the Large Hadron Collider. In order to create certain bosons, like the Higgs of recent discovery, scientists need to create small spatial regions of huge energy. They do this by colliding atoms. If the energy of the impact is high enough, the various fields can be disturbed enough to produce... | [
"The idea of converting matter into energy and vice versa doesn't really make sense; energy is a attribute of a thing, rather than being some peculiar state of matter.",
"Particles with mass have some of their energy as kinetic energy and some as mass energy; massless particles like photons have all their energy ... | [
"how much energy do you need exactly?"
] |
[
"I don't know exactly how to phrase my question, but... Why does math *work*?"
] | [
false
] | How is it that we can write out a formula and use that to make sense of our reality? What is the connection here that I am missing? | [
"This is partly by design: Early mathematics was developed to reflect how the logical structure of the world (counting units for transactions and planning, measuring areas). Later mathematics was developed from early mathematics, so it's perhaps not entirely surprising that (some of) it, too, reflects how the world... | [
"that's not necessarily math. our measurements are relatively arbitrary. which explains why we have various forms out there like the metric and the imperial systems. You can read up more on that ",
"here",
".",
"The standard method of determining mass, a scale, actually determines weight, but based on what we... | [
"I think to answer that question, one should think of mathematics as relationships, how numbers can relate to each other. In application, if any relationship exists, it can be represented by numbers and modeled (Physics is a giant model for the universe). If no relationship exists, it can't be modeled in the same s... |
[
"Benefits and, or disadvantages of hemocyanin oxygen transport rather than hemoglobin?"
] | [
false
] | Is one all around more efficient than the other, or only under certain situations is one more efficient? Does the difference in copper vs iron provide any sort of bacterial or viral resistance? Or possibly lower chance of infection due to open wounds? | [
"I believe there's only one creature in existence that uses hemocyanin, and that's the ancient horseshoe crab. From what I know, hemocyanin is a woefully inefficient oxygen-transporter in comparison to hemoglobin.",
"Any benefits that hemocyanin provided were dwarfed by its inefficiency; which is why there's only... | [
"Well there is more than one. Many octopus species also use hemocyanin, and have returned to \"shallow\" waters compared to their horseshoe crab ancestors"
] | [
"Compared to the billions of life forms that don't utilize it, I wouldn't be surprised that the original point still stands."
] |
[
"If space is frictionless, why is the limit on how fast our rockets can go so close, wouldn't a big enough rocket constantly accelerate?"
] | [
false
] | Pretty much, I know right now our rockets can only try like 1% the speed of light. I'm saying if we attached a HUGE fuel take to a rocket, and it continuously went for a long long long period of time, wouldn't it constantly accelerate until the fuel ran out? Allow us to go fast than that 1 percent? I don't know much ab... | [
"Okay, so fuel has mass. The more mass you add, the more thrust you need to move it, which means bigger engines and more fuel, which means more mass... ",
"All kidding aside, at a certain point adding more fuel becomes impractical. You have to put the fuel in a container, add more structure to the ship, etc, etc... | [
"A ",
"solar sail",
" is one example of a propulsion system that doesn't use on-board fuel"
] | [
"A rocket pushes exploded fuel out the rear end."
] |
[
"Is the 'Tongue Map' actually a real thing?"
] | [
false
] | null | [
"You are correct, the \"tongue map\" concept isn't true and generally isn't taught any longer. Your biology teacher should get with the program!"
] | [
"^ It's an ",
"old misconception"
] | [
"Thanks alot! Ohhh its good to be right.",
"EDIT: Oops I'm in my other account :P"
] |
[
"Do all orbitals have infinite ranges with only specific regions of high probability of finding an electron? And if so, does it mean that technically an atom is infinite in size?"
] | [
false
] | null | [
"All bound-state wavefunctions for a Coulomb potential have the property that there is no distance beyond which the radial wavefunction is always zero. So they technically extend to infinity.",
"But the “size” of the atom is usually defined in terms of an RMS charge radius, or something similar, which has a finit... | [
"The electrons don’t jump around between different positions, they simultaneously exist at all positions, according to the probability density function given by the squared modulus of the wavefunction.",
"But to answer your question, an electron can’t simply escape from an atom for no reason. Something has to cau... | [
"Alright, thanks a lot."
] |
[
"Does the infinite set { 3, 3.1, 3.14, 3.141, ... } contain the whole number Pi?"
] | [
false
] | null | [
"Well technically this sequence is a sequence of rational numbers converging to Pi. In a sense, the sequence IS Pi, isn't it ?",
"No single element in the sequence is Pi, but the sequence contains all the information to know Pi."
] | [
"One definition of real numbers is using ",
"Cauchy sequences of rational numbers",
". Transcendental numbers ",
" sequences (up to an equivalence relation).",
"My point was not to go into semantics but to provide information beyond the basic question of the OP."
] | [
"Say you have an infinite set with the Nth element represented by Pi to N digits:",
"{ 3, 3.1, 3.14, 3.141, 3.1415, ... }",
"Does this set contain the number Pi with infinitely many digits?",
"No. Pi does not appear at any point on the list, so it's not in the set. Simple as that. There are numbers in the ... |
[
"Why is it that no soldering can be done on an aircraft, so they use rivets ?"
] | [
false
] | null | [
"Solder is sensitive to fluctuations in both temperature and pressure. Airplanes are exposed to massive amounts of both.",
"But that’s only the shell; in the climate controlled areas, there’s lots of soldered electronics."
] | [
"There is soldering and then there is welding. Generally soldering produces a joint weaker than the base metal. Solder doesn't work very well on Aluminum. So you won't see soldering on aircraft structures.",
"",
"Welding can produce strong joints. However some disadvantages.",
"",
"Welding aluminum produc... | [
"I work on a national neutron science facility. We had airbus bring one of their A380 wing struts and scan it to see if the (then) newly developed friction-stir welding is as strong as rivets. The idea being that millions of rivets in a plane adds a significant mass (I.E. fuel and money) so they wanted to replace t... |
[
"How can chess computers be programmed so that it can be so accurately adjusted to a skill level ranging from a beginner to a grandmaster?"
] | [
false
] | Nowadays, even the Chess apps we can download on our phones can be set to a skill level of your choice based on Elo. How can these computers be programmed in a way that it can cater for every player's skill level? What is the difference in programming of a computer that is set to play you at the equivalent of a profess... | [
"There's nothing accurate about how they do this I think :)",
"You can definitely weaken a chess engine by artificially restricting the depth to which it searches for tactics and in other ways.",
"What is very hard is mapping that to human skill levels, and especially making it play convincingly like humans of ... | [
"There's no general theory of how to do this, I'm afraid. I've seen the code or discussions about this for a handful of engines, and they do different things.",
"The one I recall off the top of my head is ",
"Stockfish",
", which, going from memory, when you tell it to lower its level of play:",
"(2) is ac... | [
"The way they map the AI to player skill is rather simple: just meassure elo rating."
] |
[
"\"Photons\" of different EM spectrum?"
] | [
false
] | If photons are particles of light (visible light? correct me if I'm wrong), do photon equivalents of x-ray or gamma exist? | [
"All electromagnetic waves are made of photons -- visible light, radio waves, X-rays, gamma rays, ultraviolet light, infrared light, you name it."
] | [
"Yup! Your wifi router, which broadcasts radio waves, is basically a strobe light that blinks in an incredibly fast and precise way in a color that you can't see."
] | [
"So photons are a general term that apply to all EM waves?"
] |
[
"What is happening when our brain is \"waking up\"?"
] | [
false
] | Do certain processes "boot" later than others? How does the brain prioritize which systems come online first? Why aren't we firing on all cylinders right when we wake up, sometimes taking up to an hour before we're fully cognizant for the day? | [
"formatio reticularis",
"Don't wave your hands around while saying that or you'll summon a demon."
] | [
"So, the feeling that \"your body is awake but your brain is not\" is caused by melatonine ?"
] | [
"So, the feeling that \"your body is awake but your brain is not\" is caused by melatonine ?"
] |
[
"Does a battery lose mass as it discharges?"
] | [
false
] | On one hand, no atoms are going in or out, so the mass should always be the same. On the other hand, we have E = mc , relating mass to energy. As charge / energy is lost, so is mass. | [
"Mass-energy equivalence always holds, it just often has negligible effects. A molecule formed in an exothermic reaction is a little lighter than the unbound atoms assuming kinetic energy stays the same, but due to the small energy involved with bonding (compared to the atoms' rest mass), the effect is pretty much ... | [
"In principle, yes. However, the energy you take out of a battery is tiny compared to the rest mass, so the effect is completely negligible. A good battery has an energy density of a few 100 Wh / kg, let's assume ρ = 1000 Wh/kg = 3.6 MJ/kg to be on the safe side. Converted to a mass fraction, this is μ = ρ/c",
" ... | [
"Do yourself a favour and grab a fine-sensitivity scale. Measure the weight of a battery before and after charges.",
"Likewise, try dropping the battery pre/post and see how the bounces differ depending on the charge-state."
] |
[
"Does everything orbiting the Sun equate to as much or more mass as the sun itself?"
] | [
false
] | Wondering if you combine all the planets and other bodies of mass of any sort equal to as much or more mass than the Sun itself. If not is it possible for this to occur? | [
"Not even close. The sun is well over 99% the mass of the solar system; it's over 1000 times the mass of Jupiter, which itself is more massive than everything smaller combined."
] | [
"There are some diagrams that show the Sun and planets to scale. This one, for example:",
"https://twistedsifter.files.wordpress.com/2014/11/our-solar-system-in-perspective.jpg",
"As you can see, the Sun is about 10 times the diameter of Jupiter, and volume scales with diameter cubed, so assuming the same densi... | [
"Piggybacking on other people's responses to post this to-scale representation of the solar system, including distances, if the moon were only the size of one pixel.",
"http://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html"
] |
[
"How does a mirror reflect light? How can a mirror absorb light and re-emit it at an angle?"
] | [
false
] | How do mirrors reflect light? How can they absorb light and send it at an incident angle? Also, if a reflective surface can absorb light and send it at an incident angle, why doesn't there exist "retro-reflective" surfaces to send light straight back to the light source? Thank you! | [
"Mirrors actually reflect at all angles, it's the interference of the light waves that cause them to rebound like they do. If you think of the light as a wave moving in all directions from a point, you can see that if it hits a boundary it will bounce off. The way it does that is to have each point on the mirror ac... | [
"I second the book QED, as a layman in the field i loved the way Feynman could describe things with such brilliant analogies and make things really easy to understand."
] | [
"The reflection of light from a mirror actually is not absorption and emission of light. What happens is the electromagnetic field of the field causes the electrons in the reflecting material to arrange themselves such that they make a field which cancels the electromagnetic field of the light. The light cannot be ... |
[
"AskScience AMA Series: We are Drs. Roger Hanlon, Mike Vecchione, and Louise Allcock, and we research octopuses, squids, cuttlefish, and other cephalopods. Ask us anything!"
] | [
false
] | Hello reddit! We study octopuses, squid, cuttlefish, and other cephalopods (we even wrote a book together called ). Why are cephalopods amazing? Let us count the ways: My name is Roger Hanlon, and I'm a senior scientist at the Marine Biological Laboratory in Woods Hole, Massachusetts. I am a diving biologist who studie... | [
"Do these animals engage in any sort of sophisticated coordinated efforts? Working together on interesting ways?"
] | [
"Can an octopus teach the use of tools to its offspring in a suitable environment? In other words could octopi lineage develop use of tools and even a culture regarding said tools if they were more social creatures?"
] | [
"Thank you for doing this AMA, cephalopods are really interesting (possibly the most interesting invertebrates).",
"I follow the EVNautilus live stream and they recently came upon ",
"large swarms of brooding deep sea octopus",
". These creatures were in a really strange position, and at the time, the researc... |
[
"Is the native GaAs oxidation layer water soluble and if yes, why are then acids used to remove it from wafers?"
] | [
false
] | I read that Si and GaAs, which are both used as semiconductors in computer chips, develop a very thin oxidation layer in air. I also read that the one that Si develops is insoluble in water, so it is a good passivation layer, while the one that GaAs develps contains water soluble oxides, so it is not a good passivation... | [
"I'm afraid I don't know much about GaAs, but I do know about silicon. ",
"In terms of the nature of the oxide layer. You can think of it like this - in the bulk of your silicon, each silicon atom has four neighbors. However at the surface this can no longer be the case. Instead the silicon at the surface have 'd... | [
"Thanks, very interesting. I came across a source that said those two materials have somewhat similar oxidation behavior, so you're probably right - thanks, I learned something, even as a non-chemist!",
"I'm still curious why they don't just use water, but maybe someone will still answer here..."
] | [
"Happy to help. What is your source on these soluble oxides? Oxides generally are quite stable, so I am surprised to hear that GaAs oxides are. ",
" on the other hand are commonly water soluble."
] |
[
"Why is it that we have evolved to eat cooked food? Doesn't cooking the food remove various nutrients?"
] | [
false
] | Is it something to do with being able to digest meats easier? If so, is it worth the trade off? I know that chimpanzees eat raw meats, and i'm not certain but i'm guessing early humans ate raw meats as well. That means we have actively evolved to eat cooked foods. Why? | [
"This probably isn't true.",
"http://www.sciencedirect.com/science/article/pii/S1095643303000205"
] | [
"It also kills some/most/all harmful bacteria"
] | [
"My totally non-medical opinion is that it's BS, for a few reasons. We're evolved to use agriculture, we can't support our population on a foraging diet, agricultural societies live longer, our civilization is predicated on it, and there's no evidence that the supposed \"paleo diet\" is actually what paleolithic m... |
[
"How can a bird stick it's neck out if muscles can only pull?"
] | [
false
] | I have seen my bird extend it's neck to almost twice it's normal length. How does it work? | [
"This is a very good question.",
"It's essentially the same way you hold your head up. There are muscles running up the vertebral column on all sides. The neck is articulated by adjusting the tensions on opposing sides. Birds typically carry their heads with their necks in an S curve. This curve is straighten... | [
"As the others have said, the bird is essentially straightening it's vertebral column. The vertebral column in most animals looks remarkably different from the visible neck. Check out this blog post for some excellent examples:",
"http://svpow.wordpress.com/2009/05/31/necks-lie/",
"One diagram is of a small b... | [
"The author of this post, along with a couple of other regulars, have a paper published about how dinosaur necks are often illustrated in ways which don't make a lot of sense biologically. I don't think they suspect sauropods pulled back like a turtle, but had a more s-shaped neck and less of a horizontal, stickli... |
[
"Anthropologists, Sociologists, Psychologists of Reddit - Are humans the only specie that seeks gratifications by watching porn?"
] | [
false
] | [deleted] | [
"http://www.abc.net.au/science/articles/2005/02/08/1298389.htm",
"http://joshuapundit.blogspot.com/2010/05/proof-monkeys-willing-to-pay-for-porn.html?m=1",
"Apparently other primates \"enjoy\" porn. There was more i just googled \"monkeys watch porn\" and \"primates watch porn\" "
] | [
"Just for future reference, the singular form of \"species\" is also \"species\". The word \"specie\" does not have a biological meaning.",
"In addition to the reports on 'primate porn' given by SeeDickRun, there have been attempts to promote sexual arousal in giant pandas by showing them videos of panda mating, ... | [
"Although I am not an expert in this field by any means... I did watch a lot of Animal Planet and Discovery Channel.",
"To get Stallions and Bulls to ejaculate into a receptacle they usually have fenced off lady within viewing distance. I watched this purely for educational purposes. "
] |
[
"How far can electricity travel through our electrical grid?"
] | [
false
] | For example, if every power plant in the country shut down save for the Hoover Dam, how far could that electricity travel? | [
"For long distance transport, power is converted to a very high voltage and transported in high-diameter cables, usually Al for cost. ",
"A very naive calculation (300kV_RMS and 750mm",
" cross-section aluminum wire @ room temperature) assuming all the power of the Hoover dam is used (that's 2080MW) says that t... | [
"AC power systems transmit and dissipate the same power system as DC does. The current is constantly varying in AC, but the common way to refer to it is an RMS current and voltage. If you multiply the RMS voltage by the RMS current, you get the power in Watts.",
"Example: A 120VAC (RMS) line with 1A (RMS) flowing... | [
"While in AC power systems the electrons do not generally move, it is not entirely related to how much losses you have. ",
"AC losses are generally controlled by having very high voltages in large diameter conductors."
] |
[
"I have grown up in a northern country where there we have really cold winters and lots of snow. My forefathers have always lived here too. Does this give me any perks in ways of being better suited for cold weathers? Perhaps other things? Also the other way around."
] | [
false
] | [deleted] | [
"I believe what you've described in your example is acclimatization. While the ability to acclimatize well to any given environ no doubt leads to adaptation I don't feel this is the best example possible, but then you've said so yourself already.",
"While adaptation to climates within human populations is no doub... | [
"I believe what you've described in your example is acclimatization. While the ability to acclimatize well to any given environ no doubt leads to adaptation I don't feel this is the best example possible, but then you've said so yourself already.",
"While adaptation to climates within human populations is no doub... | [
"Yes, this is not necessarily a genetic difference. In fact, all northeners are probably familiar with how much less acclimatized to the cold you are in the fall, while the same temperature in winter or spring feels quite nice.",
"I can't source this at the moment, but I believe some groups have a trait which pro... |
[
"How does formaldehyde preserve tissue?"
] | [
false
] | And does it work in all species? Would it work for a fish? | [
"Formaldehyde works mostly by cross-linking proteins. It causes a reaction that binds the loops and coils of an indiviual protein to each other, and also binds parts of each protein to other proteins nearby. ",
"This has three main results. One, it kills any bacteria that could decompose the tissue. Two, it deact... | [
"Thank you!! I work on embalmed bodies and I had no idea of the mechanism. This is such a great explanation!!!!"
] | [
"Follow up question because you seem so knowledgeable about this - how does cold methanol fixation work? Ive seen it used for some applications like ICC staining of cytoskeletal proteins but could never find an explanation for how it preserves them."
] |
[
"Question about the theory of the Multiverse...."
] | [
false
] | There is a theory within the scientific community that the BIG BANG was actually the result of two universes colliding with one another. Whether it is the most popular or the most plausible I will leave to the scientists but I have a question about the theory. Now basically it states that two Universes collided togethe... | [
"There is a theory within the scientific community that the BIG BANG was actually the result of two universes colliding with one another.",
"Not really, no. That's more of a wild speculation. It's not reasonable to call it a \"theory\" until the speculation is translated into some kind of objective prediction abo... | [
"I've heard you mention a few times that there is no evidence for any kind of multiverse. I've read about the many-worlds interpretation of quantum mechanics which, if I understand it, stipulates that the quantum nature of waves mean they exist as all possible states simultaneously. Various perturbations collapse t... | [
"The sci-fi/comic book Multi-World Interpretation (MWI) is that every choice that gets made divides the universe into two separate universes and so on such that there are an infinite number of universes in which case every choice was made in any one of them. The real MWI is so much more boring. It pretty much boils... |
[
"Can a fission explosion occur naturally?"
] | [
false
] | I’m currently studying nuclear physics and was wondering if it’s possible for a natural source of uranium 235 to have enough of that isotope to form a critical mass. I know it’s usually around .7% but has there ever been a case where an unusual amount formed? | [
"I am unaware of a naturally occurring fission ",
" per se. However, we have evidence for natural sources of uranium-235 becoming critical and thus undergoing sustained fission reactions. ",
"Specifically, there is a deposit of uranium in the Oklo Mine in Gabon. About 1.7 billion years ago, it went critical, th... | [
"Yes (to a reaction ...but no to an explosion as ",
"/u/restricteddata",
" has pointed out).",
"There is a well-documented case of natural fission reactions at ",
"Oklo, in Gabon, Africa, 2 ",
" billion years ago",
".",
"The article describes four important criteria that were met at Oklo to enable nuc... | [
"Though it should be noted that this was not an explosion. It was a chain reaction. But not an explosive one. It was, as the article notes, a natural nuclear reactor. Not a natural nuclear bomb.",
"(Bombs can't use moderators — the reaction needs to be faster than that. So they need much higher levels of enrichme... |
[
"What purpose do toe nails serve?"
] | [
false
] | [deleted] | [
"Same as fingernails. They protect the superior aspects of your toes and add some structural integrity to them.",
"You would probably not feel they were so pointless if you didn't wear shoes all the time. Think about the benefits of your fingernails, would you argue they are useless? Your toenails, from an evo... | [
"Not everything has to serve a purpose. I know fingernails serve a purpose to protect the fingertip and to help with delicate gripping. Even if it doesn't serve a purpose, it's still an evolutionary heirloom from the days of claws."
] | [
"I prefer my toe-nail get crushed than to chip the end off the bone when I drop a brick on my foot."
] |
[
"Why do cats go still if you grab the back of their necks?"
] | [
false
] | I don't mean why it's a useful trait, I'm wondering what is actually making them stop moving around. | [
"The exact mechanism is still being investigated, but ",
"research",
" shows that there is forebrain activity associated with \"Pinch-Incuced Behavioural Inhibition\" (PIBI), more commonly known as \"clipnosis.\" ",
"There is also significant contribution from the parasympathetic nervous system, as the calmin... | [
"You seem to indicate that you know this already, but if anyone else is wondering, the trait is useful because it allows mothers to carry their offspring easily and quietly from place to place."
] | [
"Thank you! ",
"whoever thought of the term clipnosis deserves an award... "
] |
[
"Is it fair to say that all of your atoms will arrange themselves together multiple times after enough amount of time?"
] | [
false
] | null | [
"The wikipedia article on the ",
"timeline of the far future",
" says that the expected time before the observable universe repeats itself by chance is 10",
" years.",
"Contrast this against the 10",
" expected years for a fully formed and (temporarily) functioning brain with memories, desires and dreams ... | [
"but still, infinite time, that brain may as well, after a good chunk of time, appear on a planet similar to earth. Is it statistically impossible?"
] | [
"I'm not sure what you mean by \"it\" or \"statistically\" in \"Is it statistically impossible?\". The probability of a copy of your brain spontaneously forming on a spontaneous copy of the earth is non-zero, assuming quantum physics is correct (erm.. I think..), if that's what you mean. On the other hand, it's ",
... |
[
"When Turing came up with the Turing machine, how did he justify that it is indeed the essence of computation? Did he know for sure, that you can't build a more powerful computer in real life?"
] | [
false
] | [deleted] | [
"The turing machine was actually developed in order to answer a different question than \"what is computation\". The goal was to answer the ",
"Entscheidungsproblem",
", which was formulated by Hilbert and sits squarely within the realm of traditional mathematics. The paper title was \"On Computable Numbers, wi... | [
"A Turing Machine is one type of automata, however there are others. Turing Machines are mathematical representations of algorithms which can process recursively enumerable languages; there are other types of automata that can process more and less restrictive languages.",
"A single Turing Machine can be thought... | [
"Why don't we translate certain words when we use them in English? Entscheidungsproblem is the immediate example, but I've thought this about the word Zeitgeist as well. Would using the term \"decision problem\" muddy the conversation too much?"
] |
[
"Why can looking at a solar eclipse blind you in seconds versus looking at the sun normally?"
] | [
false
] | [deleted] | [
"The \"blind you in seconds\" part is an exaggeration, but there is an explanation for why looking at a solar eclipse can be more harmful than looking at the sun normally.",
"When you normally step outside into the sunlight your retinas contract to limit the amount of light coming through. The sun puts out a lot... | [
"One correction: your irises open and contract, not your retinas."
] | [
"semi-related question: When I was young and stupid, I used to look at the sun by looking at it from the corner of my vision, which caused that area of my vision to turn dark blue, and by slowly moving where the sun was in relation to my field of vision, would be able to look directly at it without discomfort (it ... |
[
"Why don't we see the sun's light going past us at night?"
] | [
false
] | If night and day are the rotation of the earth, why don't we see the light beams going beside us when we are turned away from the sun? | [
"You can't \"see\" light beams in general. Light has to go directly into your eye for you to see it. The only reason why you can see something like a laser on earth is because some of the light bounces off dust particles suspended in the air."
] | [
"I like to say that you can only see light when it slams into your eyeballs."
] | [
"Look at the moon. The moon \"glows\" because it is being lit by the sun. In other words, some of the light that was \"going past us\" bounced off the moon and went toward Earth, specifically your eye. "
] |
[
"Nutritionally speaking, isn't having Kool-Aid with a vitamin pill just as good as drinking Orange Juice?"
] | [
false
] | [deleted] | [
"Well, ",
"cranberry juice may not be a good (bad?) example because it seems to have some nice Phytochemicals",
" which aren't in your typical vitamin pills, but in general if you already have a balanced diet, juice drinks aren't much better than sugar water. ",
"What I've been told is that if you really wan... | [
"I think the fallacy here is that you're trying to think of something as complex as food in terms of its \"goodness\". When you make a comparison like this, you engage in a dichotomy that really doesn't help you make wise nutritional decisions. To try and engineer something as opaque as \"health\" using such underp... | [
"My dentist considered both equally bad. ",
"She recommended beer."
] |
[
"How can we have a vaccine for a lifelong disease, like herpes, that our bodies can't normally fight off?"
] | [
false
] | null | [
"It helps to understand how the virus evades the immune system. Unlike a retrovirus, which actually writes its genetic makeup into cells to spring up later even after active viruses are gone (think HIV), so there is never really a \"cure\" once the virus sets in. With Herpes, the virus prevents the cells it infects... | [
"A lot of viruses either overwhelm the immune system. Or trick it. Or they find a place in the body to hide. ",
"Vaccines can teach your body to spot the virus, have a head start on how to fight it, or kill it off before it can hide. "
] | [
"Thank you, that was excellent. "
] |
[
"Do hurricanes hit the east Atlantic?"
] | [
false
] | We always hear about hurricanes in the Atlantic hitting the east coast of the US, Caribbean, etc. The west side of the Atlantic. But I can't remember ever hearing about them hitting the west coast of Africa or anything like that. Is that just US focusing on US and not talking more about the outside world, or do they re... | [
"Generally, the sea surface temperatures are too low to support hurricanes near mainland Europe. Wind shear is also usually too high, and towards Spain and far NW Africa, dry air and a general lack of weather disturbances during hurricane season also reduce the opportunities for tropical cyclogenesis in otherwise m... | [
"To add, quite frequently a hurricane will drift North after landing in the US (sometimes before) before heading back East over the North Atlantic, usually as a storm remnant packing gale force winds and heavy rain.\nWestern Europe (UK and France especially. Spain and Portugal occasionally) often receive the remnan... | [
"To add, quite frequently a hurricane will drift North after landing in the US (sometimes before) before heading back East over the North Atlantic, usually as a storm remnant packing gale force winds and heavy rain.\nWestern Europe (UK and France especially. Spain and Portugal occasionally) often receive the remnan... |
[
"Are there any materials that are harder then steel but aren't made from any oils?"
] | [
false
] | null | [
"Hi interestedinscience0 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 o... | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"If you disagree with this decision, please send a ",
"message to the moderators."
] | [
"Carbon fiber and the new materials are made using oils and steel is a finite supply so are there any materials that are harder then steel but made with no oils?"
] |
[
"How could a large skyscraper in a densely populated area be demolished?"
] | [
false
] | What if a large skyscraper such as the Willis Tower in Chicago had to be demolished for safety reasons? It's not like a big stadium where you can implode it into itself. Would you just take it apart piece by piece starting from the top? | [
"Skyscrapers are dropped using a controlled demolition of key supports, in the center of the building. While it does create a big cloud of dust around the footprint of the building, the heavy debris collapses inward on itself, then straight down. Sorta like this: ",
"|==| building roof",
"\n|-V-| buildin... | [
"One Meridian Plaza was a 38 story skyscraper in Philadelphia burned in 1991 and was dismantled piece by piece from the roof down to the sub basement in 1998-1999. A taller condo tower stands there today.",
"In the period between the fire and the building's demolition the surrounding blocks were more or less aban... | [
"Here in my built up South East Asian city, top down demolition is the rule, not the exception. Basically an excavator equipped with a pneumatic jackhammer is put on the top of the biliding, and it works its way down floor by floor. The Japanese, who else, have made it almost into ",
"an art",
".",
"Edit: aut... |
[
"How soon are antibiotics likely to run out?"
] | [
false
] | [deleted] | [
"The problem with this situation is completely how you define the post antibiotic era.",
"Do you define it as a bacteria existing (even if rare) that is ",
"resistant to common treatments?",
" If so then we are already there.",
"Or do you define the post antibiotic era to be when such bacterial infections a... | [
"There are two reasons antibiotics are \"running out\".",
"1) Bacteria are becoming more and more resistant to antibiotics. Antibiotic resistance has always existed in some form. Antibiotics are used in nature by bacteria and fungi to kill competitors, and as a result, some bacteria have evolved defences against ... | [
"There are two reasons antibiotics are \"running out\".",
"1) Bacteria are becoming more and more resistant to antibiotics. Antibiotic resistance has always existed in some form. Antibiotics are used in nature by bacteria and fungi to kill competitors, and as a result, some bacteria have evolved defences against ... |
[
"What would the sky look like, if our solar system would be anywhere near the galactic core?"
] | [
false
] | How many stars would we see? Would we see some during day time? How close would be the next star in average?.... Thanks for any replies. | [
"What would the sky look like, if our solar system would be anywhere near the galactic core? ",
"It would be bright. I mean, like ",
" bright. In fact, you wouldn't distinguish between day and night, because, well, there is no night anymore. It would be continuously bright because of the vast amount of stars, ... | [
"hey, fellow german, thanks for your reply. Could a solar system like ours exist in a nebula, like the Horsehead nebula, or soemthing similar?"
] | [
"Wouldn't a star that size just attract all of the mass in the nebula due to its own gravity?"
] |
[
"Does this or can this kind of mirror exist?"
] | [
false
] | A mirror like . One side acts as a mirror or reflects most light. The other side reflects or absorbs (doesn't matter which) any color except for a specific range of wavelength, like the color red, which it lets through. My instincts tell me no. So, "one way" mirrors aren't what I thought they were. Also, are interestin... | [
"There are some basic physical principles that prevent this, and there are no real one-way mirrors, even for just a singe wavelength. Read about ",
"Maxwell's Demon",
" to find out why."
] | [
"I didn't ask for a 100% one way mirror, that's why I offered the option of reflecting \"most\" light.",
"There cannot be ",
" between the two directions. Not 1 percent, not 0.001 percent. If this existed, it would violate basic thermodynamics. The article explains why."
] | [
"Then I'm misunderstanding you.",
"There cannot be any difference between the two directions.",
"One way glass exists. On a ",
"lighter note",
"."
] |
[
"Is a drug-resistant TB epidemic possible?"
] | [
false
] | I just read the front page article on the TB coverup in Florida, and the comments really freaked me out. Would a catastrophic/apocalyptic TB epidemic be a possibility in the coming months or years, or is that just scaremongering? | [
"Searched",
"Relevant ",
"discussion",
"Original question by ",
"TubeZ",
"With recent articles about Totally drug-resistant TB, is there reason to be concerned about it?",
"Relevant comment courtesy ",
"Teedy",
"TB spreads as airborne spore, and has well and truly been very nearly eradicated for mos... | [
"I think the above comments sum things up pretty well, but I have just one nit-picky comment about Teedy's reply. As far as we know, M. tuberculosis does not form spores. It is very resilient and can survive for months to years outside of a host with no nutrition (",
"Source",
"), but it still is not quite as... | [
"Thanks for the correction! :)"
] |
[
"Why do Iron Filings in a magnetic field form distinct lines around a magnet?"
] | [
false
] | A good example of this is this video. Why are the filing arranging themselves into wave-like patterns around the magnet? As far as my knowledge goes, the field strength should not fluctuate like this. Edit: BrainSturgeon put this question in a better way - Why are magnetic materials organized around magnetic field line... | [
"If the OP will allow me to clarify the question: ",
"I think it's understood that things align north-south according to the field lines, but what about the lateral spacing between? Is there some sort of repulsion between adjacent magnetic materials lined up with the field?",
"Related: ",
"Ferrofluid",
" ... | [
"Why don't the iron pieces clump together in a huge mass? Why is there space between laterally adjacent iron pieces?"
] | [
"Thank you, this makes perfect sense."
] |
[
"Time dilation calculations. Did I do this correctly?"
] | [
false
] | [deleted] | [
"This graph",
" show the time dilation depending on the speed. "
] | [
"Yep, about 56 days is correct."
] | [
"You did it correctly.",
"A lot of people don't realize just how fast you have to go to get a really significant time dilation effect. For instance, to get your expected result where the stationary frame experiences 5 years before seeing the traveling clock pass 1 year, the traveler needs to be moving at ",
"0.... |
[
"Can different bird species cross breed like domesticated animals?"
] | [
false
] | We cross breed dogs, cats, and even horse between different subgroups to create new shapes, sizes, and designs in our pets. I is this something we could also do with avian species? Like could we cross breed a chicken with a turkey or a duck and take 50% of the work out of making a turducken? | [
"Most of your examples (pets) are just different populations of the same species, or rarely different species in the same Genus or occasionally some shenanigans with “exotic breeds” of cat where they’re all at least Felines. Chickens and ducks are in entirely different orders and to my knowledge far too different t... | [
"What's this user says. It depends on how close the two species are, all of the domesticated dogs are basically just reshaped wolves. I do not know if there's a similar \"wolf\" for domestic cats",
"A good example might be horses and donkeys. They can interbreed and reproduce, but The offspring are sterile. There... | [
"You can and people do breed two chickens to be more lean, fat, short, tall, ect to give different types of chickens in a similar way."
] |
[
"How much do we know about the \"circiutry\" of the brain?"
] | [
false
] | Have neuroscientists found specific logic gates or anything resembling one in the brain? How much do we know about how the brain calculates things? I know we haven't exactly mastered the art of artificial intelligence, but about how close are we to understanding the brain? | [
"It's a really fascinating field - here's an example of a network that controls motor activity, called the ",
"basal ganglia",
".",
"Cells in a regions of the brain called the substantia nigra pars reticularis and the globus pallidus internal provide a inhibitory signal to the thalamus, and suppress motor fun... | [
"To answer your question more broadly, we know a lot about some very specific points (as in arumbar's example) but very little elsewhere. I think we all agree that we are a ",
" long way away from throughly understanding the brain as a single integrated system.",
"Part of this is a problem of scales. There are... | [
"to be fair, those examples you used are in completely different regions of the brain. ",
"parkinson's loss of dopaminergic neurons is secondary to death of cells within the ventral tegmental area, largely. huntington's chorea is dysfunction within the subthalamic nucleus"
] |
[
"Is leaving a computer on for periods of time better or worse than continuously shutting it down after use?"
] | [
false
] | After I am done using my laptop/desktop is shutting it down more favorable than leaving it on? (purely from a performance point of view) | [
"Shut it down! The hard drive is still a mechanical device, and the motor can wear down over time. There's always reading and writing going on when the computer is on. Also, the fans which keep spinning to keep it cool will collect dust much faster since it's spinning 24/7. And last but not least, it saves on e... | [
"Hard drives that idle (are not requested for information) for more than 3-5 minutes spin down and stop running. What's more, I'm not sure where you heard of fans collecting more dust due to motions, but it'd make more sense logically that they'd collect more dust while idle than moving, since the air currents woul... | [
"I stand by my statement that with today's operating systems and typical user environments, the hard drive ",
" is idle. There are so many different components and system functions that are constantly reading and writing to the hard drive.",
"Also, dust particles are constantly passing through these fans into ... |
[
"Do stars exist that only emit infrared light?"
] | [
false
] | [deleted] | [
"Bodies radiate electromagnetism at different wavelengths based on their temperature. ",
"Infrared, radio waves, light, x-rays, etc. are all em radiation at different wavelengths.",
"In order for a star to be doing any nuclear fusion it has to be hot enough to emit visible light. ",
"There are brown dwarfs w... | [
"Generally, pretty much any star will emit at least some visible light. They are, after all, powered by nuclear fusion; even the 'coldest' stars, low-mass red dwarfs, have surface temperatures of ~2000 K (approx 1750 C). Heat up a piece of metal to 2000 K, and it will give off a dull red glow.",
"However, by the ... | [
"You're thinking of \"quasars\", which are \"quasi-stellar radio source(s)\". \"Quasi\" is a word used to describe something like something else, but not quite that other thing."
] |
[
"Could Curiosity be seriously damaged by a martian dust storm?"
] | [
false
] | [deleted] | [
"I was watching a documentary on it and they were worried about losing communication with the rover and having it damaged and/or buried by the dust storms.. ",
"If I can find the documentary I'll post it again"
] | [
"I was watching a documentary on it and they were worried about losing communication with the rover and having it damaged and/or buried by the dust storms.. ",
"If I can find the documentary I'll post it again"
] | [
"When you're spending that much money on such a project as landing on Mars, a modicum is worth looking into. "
] |
[
"What temperature is the universe trying to get to?"
] | [
false
] | I've been reading up about how heat death would occur at some point far in the future because the universe is trying to reach equilibrium in temperature. But do we know what temperature the universe is trying to achieve for all matter? | [
"Interesting question. Strictly speaking, heat death implies thermodynamic equilibrium, that work cannot be extracted any more (see ",
"wiki",
"). However, if you look at the ",
"equations",
" for how the temperature of the Universe scales with the scale factor (the \"size\" of the Universe), it always decr... | [
"If dark energy really is a cosmological constant, then the universe will approach an empty and exponentially expanding ",
"de Sitter universe",
", which has an ",
"event horizon",
" at a fixed distance from the observer. Like the horizon of a black hole or the ",
"horizon in Rindler coordinates",
", th... | [
"That's right. To clarify, when you say \"the temperature of the universe\", what you really mean is the temperature of the cosmic microwave background. This is the redshifted flash of light that was emitted when electrons and ions produced in the big bang first combined to form hydrogen and helium about 300,000 ye... |
[
"Is all matter composed of stardust?"
] | [
false
] | And if not, just how much matter that we know and see, including our own selves, is made up of the remnants of ancient stars? Literally blows my mind that we are the product of what happens when a burning ball of hydrogen is left alone for so long, that it eventually evolves the ability to ask where it came from (us). | [
"The Big Bang basically only produced Hydrogen, Helium, and some Lithium. Everything else has to have come from nuclear reactions, mostly in stars. Even much of the Helium and Lithium on Earth is not \"primordial\" but has come from later nuclear reactions.",
"So: the carbon that makes up organic chemistry, the o... | [
"A variety of different stars. This is actually something that people seem get wrong a lot. What happens is that supernovae and winds from stars spread out and mix into the \"interstellar medium\" - the thin gas between all the stars. This gas is fairly turbulent and mixes quite well, so when it condenses into a cl... | [
"One of the big clues is that generally all the even elements are more abundant than all the odd elements - e.g. ",
"here",
". This suggests a build-up of elements through fusing together helium nuclei. That's one nice little clue."
] |
[
"If I'm looking at my bathroom mirror 1 foot away, is my reflection 2 feet away?"
] | [
false
] | Also, if a person were to stand next to the mirror, do they see the same amount of visual details of me or more amount of visual details of me, because they are 1 foot away (just like the mirror)? I assure you I am not high right now. | [
"Actually, the answer is just yes. In optics, there's the concept of an ",
", which is the apparent point of intersection of the light rays radiated from the point called the ",
". In the case of a plane mirror, the light rays never actually intersect after reflection, but you can trace their path back through ... | [
"Mirrors are weird. I will go back to dealing with brains now."
] | [
"More. They'd see the same amount as you'd see if you stood 1/2 a foot away from the mirror. Also, they wouldn't see you with left and right reversed."
] |
[
"When our ears \"pop\", what is actually popping?"
] | [
false
] | I understand that our ears "pop" because of changes in pressure based on our altitude but what is actually popping? And why do our ears feel better after they pop? I just flew to the Rose Bowl (Go Ducks!!) and was curious as to why this happens. Thank you! | [
"Just to be pedantic, it is actually the middle ear and outer ear that is separated by the tympanic membrane. The inner ear is the cochlea."
] | [
"The inner ear and outer ear are seperated by a layer of issue impermeable to the outside atmosphere called the ear drum, aka tympanic membrane.",
"When the air pressure changes by a large amount, the air in the inner ear and the air outside the ear are not at equilibrium. To re-establish that equilibrium of pres... | [
"As you ascend into the air, the air pressure decreases. This causes the air in the inner ear to expand and push against the eardrums. What occurs during the \"pop\" is that your body is able to equalize the pressure by venting the trapped air through your Eustachian tubes.",
"When the pressure increases again, y... |
[
"Why does \"turn it off then on again\" solve so many computer/electronics issues?"
] | [
false
] | null | [
"Countless types of bugs exist, all with slightly different reasons, but the gist of it is that the computer stores some stuff in memory and then does countless changes to the memory. The computer tries to keep track of what it changes, but it sometimes loses something changed. This is usually a memory leak, but so... | [
"It is because often, the problem exists because something went wrong in the computer's temporary memory, or the RAM. The RAM is what's called volatile memory, which means if power is turned off, the memory is cleared. By turning off the device in question, it effectively wipes the RAM and gives a fresh slate."
] | [
"Think of a computer as a Roomba. It's trying to do its job loyally. It has a limited set of rules by which it can operate. Most of the time, it's doing ok. Once in a while, it reaches a situation that was not anticipated by its programmers. It gets stuck kissing the cat's ass or falls of the stairs into the s... |
[
"Would it have been possible for someone in the Middle Ages to create napalm accidentally?"
] | [
false
] | So this question arises from reading Game of Thrones. Yes, its fantasy, but it raised an interesting question for me. Could napalm, or a similar substance, have been created accidentally by say an alchemist mixing various chemicals? | [
"http://en.wikipedia.org/wiki/Greek_fire",
"Not accidentally, yes. This is what the author based his idea on."
] | [
"Is greek fire chemically similar to napalm?"
] | [
"I suppose i meant that they are liquid/gel-like, and that they are very difficult to put out with water."
] |
[
"Do sparks break the sound barrier?"
] | [
false
] | Do sparks break the sound barrier? is that the clicking noise? When we hear thunder is that because the lightening is breaking the sound barrier? | [
"The lightning bolt, or rather the flow of electrons creates plasma by superheating the air to temperatures higher than the surface of the sun. Air expands when it’s hot and lightning heats the air extremely quickly and the air expands in what is basically an explosion that we hear as thunder."
] | [
"Is it the same for small sparks?"
] | [
"Ever get a static shock? You can hear it for the same reason."
] |
[
"How many atoms are split in a nuclear explosion?"
] | [
false
] | null | [
"This is pretty easy to answer, but you should know it depends on the ",
" (energetic release) and ",
" (fission or fission-fusion) of the explosion.",
"For an all-fission (atoms splitting) explosion (like the Hiroshima and Nagasaki bombs), all you need to know is that every atom split releases about 200 MeV ... | [
"All of the above is just unit conversions, but with an awareness of what units you ought to be converting. Here are the basics:",
"Every fission (atom splitting) event releases around 200 MeV of energy. MeV is just a unit of energy, just one most people aren't familiar with (it's small). Google can convert bigge... | [
"Is there a service where I can pay to have someone call me, say those words, and just hang up? Nothing weird but my goodness that's so far over my head that the less I understood the better it got. The right words are in the right places and I read every single one. Twice."
] |
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