title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Would a jar that had an absolute vacuum float or sink in water or air?"
] | [
false
] | [deleted] | [
"On water it would definitely float. Compared to the high density of water, there's not much difference between a vacuum and an air-filled jar.",
"Floating on air is much harder. In order to keep the jar from collapsing, its walls must be hard enough to resist external air pressure. And for that they need to be t... | [
"Archimedes Principle. The upward bouyancy force is equal to the weight of the gas/fluid displaced. So, it comes down to whether the \"average\" density of the jar is higher (sinks) or lower (floats) than the gas/fluid it's immersed in. What I mean by \"average\" density is that, even though the vacuum may not h... | [
"It could float in air if your jar is light enough. A glass jar is so heavy that the mass of air in it at atmospheric pressure is negligible."
] |
[
"How much water is there under the earths surface? Will springs ever stop producing water?"
] | [
false
] | Curious as to whether or not it's possible we can run out of water? | [
"MS hydrogeology grad student here. I assume you’re asking about fresh groundwater that can be used by people (e.g. not sea water or salty brines). In answer to your first question, a recent study estimated the total groundwater volume with 2km of the earth’s surface (essentially this is the water that is accessibl... | [
"Springs are not areas where water is generated, they are outlets for underground reservoirs of water known as ",
"aquifers",
". Aquifers are fed by rainwater and snowmelt that drain into porous ground at higher elevations. Springs are just lower-elevation areas where the aquifer flows out of the ground, ",
"... | [
"I believe an aquitard is something which prevents (or significantly slows) the rate of water flow. An aquifer is what holds the groundwater. ",
" ",
"Fun fact: Artesian wells form when aquifers are confined by aquitards. The pressure of the water in the confined aquifer forces water upwards through the soil, c... |
[
"Will a magnet still attract molten metal?"
] | [
false
] | Lets say you have a pot of hot liquid metal, if you stick a magnet in it will the metal still stick to it magnetically? edit 1: Also, if it does stick, can you raise the temperature of the metal to the point where it WONT stick (assuming the magnet doesn't melt) edit 2: Got some really good answers guys thanks; I really liked the earths magnetic core discussion as well. | [
"Molten iron, for example, is not magnetic because the melting point of iron is 1538 ˚C and its ",
"Curie temperature",
" is 770 ˚C. The Curie temperature, essentially, is when a metal stops being magnetic. Since the melting point is greater than the Curie temperature, molten iron is not magnetic. The same can ... | [
"then how does the earth maintain such a strong agnetic field with a core of molten iron and nickel?"
] | [
"I thought that the inner core was a solid sphere of iron? ",
"http://en.wikipedia.org/wiki/Inner_core"
] |
[
"If white noise is a random audio signal, shouldn't we periodically hear tones? Or entire songs?"
] | [
false
] | I don't understand how white noise has its own sound if it's just a series of random data. In theory, couldn't said random notes eventually produce a tone? Additionally, if we had a million speakers playing a white noise signal in their own rooms for a million years, would one of them eventually play, say, Beethoven? | [
"Well, it is not just \"random data\", it has a specific characteristic. It contains equal power within a fixed bandwidth at any center frequency. A good analogy would be white light. ",
"White noise essentially contains a lot of notes, all at once. The mixture is fairly random, and constantly changing. If it we... | [
"I can't think of a reason why, given enough time, such a thing wouldn't eventually make music. I'm not going to try to do the math to figure out if a million years is long enough to get a song out of it. My gut tells me no, but my gut is unreliable at best. "
] | [
"If we are not talking strictly about white noise anymore, this is essentially the same premise as the Infinite Monkey Theorem. And so the answer is almost surely yes, but there will not be nearly enough time before heat death of the universe for this to happen with any reasonable probability. "
] |
[
"Biology Are smaller animals/insects able to react to outside stimuli faster because their neural networks are smaller so the information travels a lesser distance?"
] | [
false
] | null | [
"The speed of action potential propagation isn't constant (like the speed of light is) across different organisms or even between two neurons in the same organism. ",
"This chart",
" can give you a good idea about the variation observed between neurons of different species (see conduction speed).",
"There is... | [
"Some information on response times. ",
"http://www.cals.ncsu.edu/course/ent425/tutorial/Ecology/defense.html",
" ",
"I suspect the fact that many insect responses are hardwired makes them speedier as there is no decision making involved."
] | [
"Thanks for your input!"
] |
[
"What is Reynolds number?"
] | [
false
] | [deleted] | [
"Reynold's number is defined as the velocity * some characteristic length over the kinematic viscosity of a fluid. You can interpret this number as representing the ratio of inertial to viscous forces. This in turn can be interpreted as how much momentum of the bulk fluid is transferred to molecular interactions. T... | [
"Good, concise answer. I'll just add that in a practical sense, in addition to indicating general flow behaviour, it's most typically used as one of the methods of assessing the dynamic similitude between fluid flow systems."
] | [
"No problem, I don't deal with fluid that much. I'm just looking over my old hydro notes here, and it seems you are right in normal circumstances. However, couldn't you just change gravity? Put the flume in a centrifuge?"
] |
[
"How to show that spin is a probabilistic property?"
] | [
false
] | For spatial coordinates we can do the double-slit experiment sending photons one by one and still getting interference pattern. What are the easiest to explain experiments one can do to check that spin is a probabilistic property? Reading wiki on the subject, it's usually just defined as such ("Spin can only have discrete values, thus if it has fixed value in one direction, it's projections on other directions are probabilistic"). Then maybe its better to ask, what are the simplest experiments to check that there's spin at all and that it's of the described nature? (Theoretically. It's probably impossible to do them at home anyway) | [
"Look up the Stern-Gerlach experiment.",
"The way it works is silver atoms come out of an oven in a stream. The structure of the silver atom is such that a single excess electron determines the spin of the entire atom. Passing the beam through a non-uniform magnetic field causes the stream to split into two (say,... | [
"Thanks a lot, will look into this."
] | [
"Stern-Ger...DrJesusPhD said it already."
] |
[
"How do scientists actually know what material the Earth's core is made out of?"
] | [
false
] | I remember in school learning that the core of Earth is made from mostly iron and nickel. ...how did we get that particular information? I can wrap my mind around the idea of scientists figuring out what the inside of the Earth looks like using math and earthquake data but the actual composition of the center of the Earth? It confuses me. What process did we use to figure out the core is made out of iron and nickel without ever obtaining a sample of the Earth's core? EDIT: WOW this post got a lot of traction while I slept! Honestly can't wait to read thru all of this. This was a question I asked a couple of times during my childhood and no teacher ever gave me a satisfying answer. Thank you to everyone for taking the time to truly explain this to me. Adult me is happy! :) 2ND EDIT: I have personally given awards to the people who gave great responses. Thank you~! Also side note...rest in peace to all the mod deleted posts in the comment section. May your sins be forgotten with time. Also also I'm sorry mods for the extra work today. | [
"It’s super interesting geology stuff! Basically we map it out by measuring the speeds of seismic waves (earthquakes) and then compare the speeds (and deflect!) of that with other elements. Once we have a match, it’s safe to presume that’s the composition",
"Of course this is a really dumbed down answer, but be s... | [
"It was hypothesised that Earth had an iron core long before we could employ seismic measurements that deep because:",
"• Measurements of the Earth’s mass in the 1800s indicated that the Earth was on average quite a bit denser than the rocks we find at the surface and even the (slightly denser) rocks brought up f... | [
"It does! As well as density, phase (gas, liquid, solid), even things like crystal structure and alloying elements will make small adjustments to velocity, as will the relative velocity of moving material like magma blooms, which all must be accounted for to get the most precise answer. ",
"Researchers are consta... |
[
"Is there a link between a person's learning of a programming language, and their ability to utilize their native spoken/written language?"
] | [
false
] | Here's my thinking, English as a language has a lot of exceptions to the rules. However programming languages seem to be more straight forward. Is there anything out there showing a strong correlation between the learning of a computer programming language, and improvements in the use of their native language. I ask this because my middle school students are learning Java as early as the 6th grade. In an unfortunate turn of events, I have a lot of students whose lexile scores are well below their grade level. While utilizing teaching methods that are more verbal and illustrative, I can get some good results from these students that typically perform poorly in writing and reading. The question is, will learning something like Java improve their ability to understand the mechanics of english language usage? Most studies point to better understanding of science and math, but I can't seem to find anything on written/verbal skills. | [
"It seems to me they think more in an \"object oriented\" speech pattern than do non programmers, in my subjective experience. That is, when they get to a certain point in the story, they make a \"function call\" to bring in more needed information relevant to the story",
"That would be \"functional\", not \"obje... | [
"As both a professional linguist and hobbiest programmer, I'll say that the link is very simple: If you know the native language of the programming language (that is, English) then you'll have an easier time learning the programming language, but aside from that there's no real link.",
"After all, spoken languag... | [
"I have a subjective experience with this, since I have a number of programmer friends. I have definitely noticed a tendency in certain individuals. When telling lengthy stories, it's apparent that programmers seem to have more digressions, bifurcations or 'branch points' and are easily able to return to the main ... |
[
"If I toss a coin 10 times and get heads each time..."
] | [
false
] | probability of getting a tails on the 11 time will still just be 50%. BUT isn't the probability of getting 10 tails on tossing the same coin 20 times 50% too? How can these both be true? | [
"Actually the probability of getting 10 tails for 20 tosses is 17.62%",
"Source: ",
"http://www.wolframalpha.com/input/?i=toss+20+coins"
] | [
"Midway through the 20-flip experiment, if you've gotten 11 heads, the probability of getting 10 tails drops to 0."
] | [
"To expand a tiny bit, 1/2 ^ 10 is 1/1024. This means if you did the \"flip 10 coins\" experiment a million times you would expect to see all heads about 1000 out of those million times. ",
"Also if you want to figure the probability of getting k heads in n coin tosses, use the ",
"binomial distribution",
" f... |
[
"We orbit the sun. What does the sun Orbit?"
] | [
false
] | The moons orbits us, we orbit the sun. What does the sun exactly Orbit? They say Voyager is about to leave the solar system, as far as I know this means it's on a escape trajectory from the Orbit of the sun. Now what will this spacecraft do next, follow a relatively similar path then our sun until some object pulls it into it's influence? And once this Voyager is in this limbo, do we know the forces that will be acting on it? Will we be able to plot this on where it will end up? | [
"Everything orbits centers of mass. The sun and the planets orbit their combined center of mass, which just happens to be very near the center of the sun. The sun orbits the center of mass of the Milky Way. At scales beyond this, galaxies don't orbit ",
", but can still be part of gravitationally-bound structures... | [
"Our Sun is gravitationally locked with two other stars in our \"local group",
"What two stars? The Sun isn't gravitationally bound to any other stars. And there isn't really any local group of stars, just stars that happen to be close to us now, and won't be in the future."
] | [
"Its also worth noting that the sun orbits at something like 220 kilometers per second, dragging all the stuff orbiting it such as Earth along with it too, and takes a couple hundred million years to make it all the way around."
] |
[
"Anyone aware of any oceanic wave phenomenon that generate slow moving straight waves?"
] | [
false
] | Years ago a saw a video that claimed there was an alignment of currents and the moon that generated slow moving linear waves. It looked pretty odd and for the life of me I can't remember what they called it. Anyone know what I'm talking about? From the original video, it was two linear waves intersecting in the ocean with people watching them. The waves were no more than 3-4 feet high each. | [
"Based on OP's description I assume \"linear\" means the large-scale spatial shape of the wave.",
"With a suitable geometry it should be possible to have two of them intersecting each other, to."
] | [
"I think you may be thinking of a ",
"tidal bore"
] | [
"Are you referring to a ",
"tidal bore",
"? There's a good and simple explanation for how they are formed in the Wikipedia article, but they're essentially formed when a high tidal range is forced into a relatively confined channel, generating waves. Tides themselves are waves caused by the gravitational gradie... |
[
"Are there any scientific studies that say beating your children is helpful or conducive to their mental and emotional maturity?"
] | [
false
] | null | [
"please tell me you are being ironic"
] | [
"please tell me you are being ironic"
] | [
"And thank Science that it is!"
] |
[
"Does a large-scale terrain irregularity database exist?"
] | [
false
] | Greetings. Considering that: The mountain/non-mountain distinction is subjective; "Land can have a degree of ruggedness whether or not it is described as a mountain. Moreover, land at low elevations can be more rugged than land at higher elevations." I'd like to know whether a database showing the proportion or index of large-scale terrain irregularities - i.e. of tens of miles or more - by country exists. The purpose is to infer the level of difficulty in the laying of infrastructure and to carry out cross-country comparisons. Ideally the database would allow to restrict the data to land with the exclusion of bodies of water such as lakes or rivers. Thanks. 1 "Consider the analogy of hills. Hills can be of varying degrees of steepness; the steeper the hill, the more exertion required to get to the top. Yet there is never any debate over whether an inclination is a hill. Indeed, public roads often display gradient ratios indicating precisely how steep a hill is: 1:10; 1:8, etc. Such quantifications make calculations of the energy required to traverse the hill possible (or, alternatively, which gear to put your car or bicycle in); a sign reading “Hill” or “Not a Hill” would not." | [
"I'm not 100% sure what you're looking for, but it seems like maps of gradients or local relief would work. There are any number of global (or near global) free data sets of ",
"DEMs",
", e.g. ",
"SRTM",
", ",
"ASTER",
", or ",
"ALOS",
". With a digital elevation dataset, it's then a trivial task wi... | [
"Excellent resources, especially the GIS blog. What GIS software and related manual would you recommend? The blog mentions ArcGIS, but the desktop base version requires an annual subscription of $800."
] | [
"QGIS",
" is a pretty full featured, free, and open source GIS program."
] |
[
"How fast can the power output of a nuclear reactor be decreased in case of power spikes in the electrical grid? (Context inside)"
] | [
false
] | Due to nice weather and low electricity use my country had to sell electricity to neighbouring France to prevent a power spike. A politician came on saying it would be wise to close NPP's and replace them by gas-powered and biomass plants, as their power output can be decreased faster than it can in a NPP. I found this: "Most nuclear reactors are hence operated in a prompt subcritical, delayed critical condition: the prompt neutrons alone are not sufficient to sustain a chain reaction, but the delayed neutrons make up the small difference required to keep the reaction going. This has effects on how reactors are controlled: when a small amount of control rod is slid into or out of the reactor core, the power level changes at first very rapidly due to prompt subcritical multiplication and then more gradually, following the exponential growth or decay curve of the delayed critical reaction. Further, increases in reactor power can be performed at any desired rate simply by pulling out a sufficient length of control rod— " Can someone give more details about this limitation in speed? How fast can you decrease the power output by, say, 10%? | [
"Actually they can adjust much more quickly than you think.",
"http://en.wikipedia.org/wiki/Load_following_power_plant#Pressurized_water_reactors",
"\n",
"http://www.oecd-nea.org/nea-news/2011/29-2/nea-news-29-2-load-following-e.pdf"
] | [
"I don't have your exact answer but a relevant fact: nuke plants are considered slow to start and stop, and are therefore treated as part of the baseload (left on for long periods of time), while other types of plants (such as natural gas, hydroelectric) are pretty quick to adjust and are used for most adjustments.... | [
"Thanks for the VERY relevant links!",
"The second one states that while load-following is ",
" possible in a nuclear reactor (more than I knew), it's harder on the equipment and the fuel. The first one seems to imply that even this difficulty does not apply in the French reactor design."
] |
[
"What's the most interesting scientific fact you know?"
] | [
false
] | There are many, many interesting things in science, but what are some of your favorite facts or studies? | [
"Most of our energy comes from a tiny little energy factory in our cells. This tiny little factory was essentially a small bacterium that our ancestral cells swallowed and they had a little microscopic Mexican stand-off. Eventually they got to know each other over the years and are now running the multi-billion cel... | [
"Parity violation in the electro-weak sector is just bad-ass. What this tells us is that it makes a fundamental difference whether you construct your coordinate system right handed or left handed. Some say in a sort of sloppy way that this means that the universe can \"tell the difference\" between right and left... | [
"Choice blindness is pretty interesting. ",
"Let's say you ask somebody to look at pictures of two different faces, and ask them to choose the one that they consider more attractive. You can then give them the picture that they ",
" choose, and ask them to justify why they chose that picture; most people will n... |
[
"when a boiler/furnace burns... does it expel both carbon monoxide AND carbon dioxide?"
] | [
false
] | or does it expel only carbon monoxide and a CO2 condensor changes the emissions into CO2? | [
"The boiler will emit both CO2 and CO, you can guestimate the amount using EPA emission factors - ",
"http://www.epa.gov/ttnchie1/ap42/",
" ."
] | [
"Incomplete combustion results in CO as a product, while complete combustion gives CO2. Since you have both in a furnace, both are products.",
"Source"
] | [
"thanks. that's exactly what i need to know. ",
"a boiler tuned properly should not emit CO. "
] |
[
"Would it be possible for two moons to orbit each other in the orbit of a planet?"
] | [
false
] | I mean in a stable orbit that could last at least a couple of thousand years. | [
"Yes. This is technically possible. In theory.",
"While we like to say things like \"the moon orbits the Earth\", the reality is that the moon and the Earth as a system are orbiting a shared point. It just so happens that the Earth is far more massive than the moon and therefore the center of that system is so cl... | [
"Moons by definition orbit a planet or asteroid. You can have a double asteroid in the Lagrange points 4 and 5 of a planet (orbiting the star in the same orbit, but 60 degrees ahead or behind), that can be stable for a very long time.",
"You can also have two objects orbiting each other while together orbiting th... | [
"For SF planning purposes, the two moons are more likely to be stable over astronomical time periods if they are much closer to each other than to the planet. So viewed from the planet, if the moons look like two little dots circling each other, you're probably fine, but if you want two big Earth-sized moons toget... |
[
"Does air have a burning temperature?"
] | [
false
] | If I had a 1m cube filled with air and just kept increasing the temperature of the cube would the air inside set on fire at some point? If this is possible, could a theoretical temperature value be applied somewhere on Earth and then engulf the whole planet with fire until no air remained? | [
"Does air have a burning temperature?",
"No. In order for something to be combustible it must have some chemical potential energy that can be released by reacting that something with oxygen. In the case of air, everything is already stable, and it would actually require additional energy to pull it apart in order... | [
"Please don't do this.",
"Again, please don't try this, because it won't work. There are much better ways of ending the world.",
"I am laughing so hard at this, thank you for the great (and funny) answer."
] | [
"There are much better ways of ending the world.",
"Please, expand?"
] |
[
"Is there any way to stop a star’s fusion reaction?"
] | [
false
] | Xenon-135 can poison a fission reaction in a nuclear reactor. Is there any analogous way of stopping a stellar fusion reaction, or would the only way to do it be to somehow blow up the star itself? | [
"If the star is not heavy enough, its gravitational collapse won't heat it to high enough temperatures to ignite any significant thermonuclear reactions. This is what brown dwarf stars are."
] | [
"Understood- I am asking about what it would take to cause a star that ",
" massive enough - where fusion is already underway - and somehow stop the fusion from continuing to occur."
] | [
"Disassemble it to reduce its mass.",
"https://en.wikipedia.org/wiki/Star_lifting"
] |
[
"Does electricity exist in 3 dimensions?"
] | [
false
] | I know that electrons are 3 dimensional objects, but one of their bi products, electricity (or other forms of radiation) I'm not so sure about. I get that electrons do have some mass, and move in more than 2 dimensions, but do the same rules apply to its more abstract products? | [
"It's not quite true that \"all particles are waves.\" They can ",
" like waves at times, and behave like particles at others."
] | [
"Either you're referring to time, which I discounted by saying \"spatial\", or you're going with one of the umpteen theories that describe extra dimensions, of which none have been shown to be correct yet, as far as I know."
] | [
"You can't discount them without discounting special relativity. ",
"Nothing in SR (or GR, for that matter) requires extra dimensions. As far as I know, the main theories talking about extra dimensions are all related to how we handle the fundamental forces and particles."
] |
[
"Why are flight times not affected by the Earths rotation?"
] | [
false
] | null | [
"First thing to think about: why are you not affected by the Earth's rotation?",
"Next, why, if you're inside a car, can you throw an object straight up and have it fall straight down?",
"Now think of the Earth as the car, and the plane as the object.",
"It's not a perfect analogy, as the Earth is a much larg... | [
"Since the troposphere (the lowest layer of the atmosphere) rotates at approximately the same speed as the Earth's surface, flying through it is analogous to driving on the surface. There is no advantage to driving or flying with or against the Earth's rotation.",
"Having said that, I will now contradict myself.... | [
"The strength and direction of the jet stream is driven by the rotation though, and that in turn affects air travel times."
] |
[
"What would the bottom of the crust and top of the mantle feel like?"
] | [
false
] | [deleted] | [
"This question actually gets at a fundamental debate within geology, or at least tectonics/geophysics. First, a few important points of terminology and clarification so that the explanation that follows make sense to everyone. 1) Their are two fundamentally different types of crust, ",
"oceanic crust",
", which... | [
"That is exactly what some have argued, and indeed, the creme brulee model (as discussed in the link to the original article) was championed primarily on the basis of observations in a particular place (the Himalayan orogen). Most observations and what we know form rock deformation experiments suggest that the jell... | [
"Is it possible that both models are right, in a sense. Like, if the jelly-sandwich model holds true in one area but the creme brulee model holds true elsewhere, dependent on a variety of factors, including the exact composition of the rock, water content and other factors?"
] |
[
"Why are some veins squiggly?"
] | [
false
] | null | [
"If all of our veins were just straight lines every time you out stretch your arm or turn your head or walk you'd be potentially stretching and ripping your interior vascular system - you need some slack in the body."
] | [
"Ah yeah that makes perfect sense now"
] | [
"Veins are very compliant vessels. This is so they can function as a reservoir for blood. They lack significant amounts of elastin fibers and smooth muscle around them. Arteries for example are typically very straight and circular. That’s due to their lack of compliance as a result of their increased elastin fibers... |
[
"Does a blind person have balance issues if standing in a boat?"
] | [
false
] | [deleted] | [
"Sorry, I can only answer part of this question. Hopefully someone else can answer the other part.",
"Your body uses a few different systems to help it maintain balance, including vision, proprioception, and the vestibular system, which all work together to help your brain know where your different body parts ar... | [
"Slightly offtopic but relevant and an easy answer. Blind people have difficulty in walking in a straight line and are not even better than blindfolded sighted people. (",
"Source",
")",
"More detailed scientific study",
" says:\nThe findings suggest that the controls of quiet stance and of\nbalancing on th... | [
"The balance system is also known as the vestibular system.",
"In the inner ear, the balance system consists of three semicircular canals that contain fluid and “sensors” that detect rotational movement of the head. Each of the semicircular canals lies at a different angle and is situated at a right angle to each... |
[
"Why do we only have fingerprints on our hands and the soles of our feet?"
] | [
false
] | I couldn't find any information on this, so hopefully this isn't like grade 2 level stuff. But yea, why do the series of lines simply break off at the end of the palm? They seem to continue as "cracks" in the skin but do not have the classic "looping" style. | [
"Also, I think the ridges serve to better sense mechanical stimuli through touch. ",
"The fingerprinted skin on your hands and feet is a special skin (glabrous skin) in that it has different mechanoreceptors as normal hairy skin and is much more sensitive and finely tuned for various mechanical stimuli."
] | [
"We don't need the extra grip for non-contact surfaces."
] | [
"A large part of mechanoreception is actually sensing mechanical vibrations, e.g. perception of fine textures is a result of scanning the finger over the surface. Having these ridges amplifies these vibrations when you scan your finger. ",
"See ",
"here"
] |
[
"So I just got my house's water quality report, anything I should be concerned about?"
] | [
false
] | null | [
"So nallen is right, drinking water is very highly regulated and held to tight restrictions. Obviously, a high concentration of anything is not good. This is a problem you don't have.",
"Your Pb (Lead) content is very low (a good thing, because it can really mess you up). Ba (Barium) is also very low. This elemen... | [
"Maybe they decided there isn't sufficient quantities in this area? I am upstate New York (Albany basically) so perhaps we don't get too much of it in runoff and what not."
] | [
"Yeah, that must be it. Hg tests are difficult (at best) so I'm going to assume they won't test for things that aren't even there to save money and time. I'm pretty sure Minnesota (where I'm originally from) tests for Hg because of the large number of lakes and the Mississippi river being natural sources of water r... |
[
"Is anti gravity technology possible?"
] | [
false
] | I just finished watching "PBS Telescope - Hunting the Edge of Space - The Ever Expanding Universe." It said that the galaxies are * expanding in defiance of gravity and this is thought to be due to dark energy. So I wondered, is anti gravity technology possible within the current understanding of the laws of physics? Or would a better understanding of dark matter be required to answer that question? Edit: * The space between the galaxies is expanding. | [
"Well... yes and no. It depends on what you mean, and on how much you think we know about gravity.",
"I assume by \"anti-gravity\" you mean a repulsive gravitational force. In the language of general relativity, gravity is a curvature of space-time. If the curvature caused by a massive object is \"positive\" t... | [
"I guess I am too stupid to even ask the question properly."
] | [
"That depends on a whole bunch of stuff. How are things arranged? What path are you taking and at what speed? Longer according to whom? "
] |
[
"Is there a reflex to wake you up if you are oxygen deprived during sleep?"
] | [
false
] | For example, if you were sleeping with your head completely covered with a thick blanket, would it be possible to get oxygen deprived and suffer health consequences like brain damage? Or would you reflexively have a reaction (e.g. moving) when oxygen deprived, even during sleep? | [
"Yes, although the arousal mechanism would likely originate first from an increase in carbon dioxide levels in your blood (as CO2 levels are the primary respiratory driver).",
"Although, if your body was exposed to hypercapnia(high C02) and hypoxia (low oxygen), you can experience a delay in arousal. ",
"Hypoxi... | [
"In a way it is. Carbon monoxide binds to hemoglobin, preventing the normal behavior of hemoglobin effectively causing hypoxia. As the primary respiratory drive is responsive to carbon dioxide levels, individuals can lose consciousness before the body detects any abnormalities. Thereby effectively dying of hypoxia.... | [
"The human body cannot detect a lack of oxygen. What it can detect is an abundance of carbon dioxide, which in most cases is roughly the same thing. If there is a high level of carbon dioxide in your blood, you will find yourself awake and panicking. "
] |
[
"How can you prove that quantum events are random?"
] | [
false
] | The question stems from this video: Here is the Wikipedia page on the topic but it's way over my head: | [
"At the moment, there is no known experiment which could determine if the the universe is deterministic or not. ",
"1",
" There are, in fact, a number of competing ideas about the ontology of the universe. Some are deterministic, many are probabilistic, some have testable consequences relative to current theory... | [
"Only if the hidden variables are observable in some way. The Bohm-de Broglie interpretation can be compatible with relativity. There is a preferred frame of reference, but it is not observable. "
] | [
"Bell's Theorem",
" tells us, that Quantum Mechanics is not governed by local hidden variables. A local hidden variable theory is one in which distant events are assumed to have no instantaneous (or at least faster-than-light) effect on local ones.",
"It says nothing about non-local hidden variables, though. No... |
[
"What would happen if everyone on earth jumped at once"
] | [
false
] | null | [
"Almost nothing, except that everyone would be in the air briefly."
] | [
"Would it burn enough calories to heat a village of 100 houses for a night?"
] | [
"The Earth is about 12 orders of magnitude more massive than every person on it. Even jumping from the same location at the same time they wouldn't noticeably accelerate the Earth."
] |
[
"What is the biggest atom that our Sun can produce?"
] | [
false
] | [deleted] | [
"Fusion of elements within stars stop with Iron. As mynameiswillem points out, elements higher than Iron require a catalyst, like a supernova, to develop. As for the largest natural occurring element, Californium. The remaining elements are far too unstable to remain naturally."
] | [
"This",
" is kind of long but essentially our sun will only be able to produce carbon.\nFusion after iron does happen. That is how we get everything heavier that iron. It just requires more energy than it puts out. Usually in the form of the gravitational collapse of a supernova. "
] | [
"my very limited knowledge of astrophysics might be of help. iirc, the heavier elements were produced by super nova, not by the fusion alone that occurs in living stars. so, because our sun is nowhere near the size needed to super nova (is that a verb?), it wouldn't be able to create crazy heavy atoms."
] |
[
"What is the neurotransmitter for pain?"
] | [
false
] | We all know that the neurotransmitter for pleasure in the brain is dopamine but can someone explain what the neurotransmitter for pain is? Also, why don't we talk about the neurotransmitter for pain often? | [
"There are many chemicals involved in pain transmission. Initially, after damage to peripheral tissues, inflammatory substances (bradykinin and prostaglandin) are released. There are sensory neurons in the tissue which are specialized for pain, called nociceptors. They are activated by an influx of ions (calcium an... | [
"Interesting. Thanks for the info!"
] | [
"Thalamus is a sensory relay station. All sensory input passes through the thalamus, except smell."
] |
[
"On r/TIL, someone posted that spacesuits, immediately after a spacewalk, smell like seared steak and/or hot metal. Can anyone explain this?"
] | [
false
] | Here is the link: | [
"According to astronaut Sunita Williams's ",
"blog",
", the general consensus among the crew is that the smell is caused by the ionization of the aluminum which comprises the ISS structure."
] | [
"skip to 2:15 \nhe does a good job explaining it ",
"http://www.youtube.com/watch?v=eiAx2kqmUpQ"
] | [
"Neat! So it (probably) isn't the smell of space itself, but instead of the space-",
"?"
] |
[
"Are neurotransmitters such as serotonin, dopamine, and GABA stored in the body like some vitamins and minerals are? Is it then possible to deplete them from chronic stress and/or bad diet? Furthermore is it possible to replenish them and cure things like anxiety and panic disorders?"
] | [
false
] | null | [
"This is sound science, but to elaborate and clarify, chemicals like dopamine , its not a matter of storage as it is how much is released during neural stimulation, and how they bind to their receptors. As mentioned there are receptors agonists and antagonists. I really do not know if on a cellular level certain ... | [
"This is sound science, but to elaborate and clarify, chemicals like dopamine , its not a matter of storage as it is how much is released during neural stimulation, and how they bind to their receptors. As mentioned there are receptors agonists and antagonists. I really do not know if on a cellular level certain ... | [
"Thank you for the response. May I respectfully ask for a paragraph break?"
] |
[
"Can an overactive immune-system benefit me in any ways I am not aware of?"
] | [
false
] | Here's my situation, I have been diagnosed with what has been described to me as an "autoimmune disorder", which has targeted my gastrointestinal system (pancreas/intestines primarily). Through some research and my doctors, I basically understand that my immune system is more or less over-active, attacking my body for no reason (that we know of). Since I'm not aware of the body having compartmentalized immune systems, could this "over-active" immune system benefit me in any overall ways I'm not aware of? edit- not asking for diagnosis or advice, I'm just curious as to the biology of the immune system and if what I ask if possible. | [
"It's possible, but not likely. Also, any benefit is probably going to be very, very minor (even trivial) compared to the problems it causes. But ultimately, it depends on what disorder you have.",
"Autoimmune disease doesn't really mean overactive immune system....your immune system is acting at a normal level, ... | [
"Thank you. That analogy really helped me understand what is going on."
] | [
"It is really of no benefit. ",
"The power of your immune system revolves around variable regions in antibodies and some white blood cells. These variable regions are responsible for detecting the surface antigens (unique surface proteins of a cell) of \"invading\" cells.",
"During the creation process of these... |
[
"How many stars had to explode to create the heavier elements that make up our solar system? How much of a heavy element is created in a supernova? How many stars had to die to create Earth?"
] | [
false
] | [deleted] | [
"MrDanger is incorrect, you can't create heavier elements through the process of neutron bombardment. You can create lighter elements, like mercury(80) to gold(79). I suppose MrDanger is ",
" correct in that neutron bombardment is occurring within massive stars, but that isn't the process creating elements heavie... | [
"Supernovas are extremely massive explosions of energy, beyond all human comprehension. It has been said that a supernova is to a nuclear bomb what a nuclear bomb is to a single flap of a mosquito wing. A huge amount of material is created in a typical supernova. According to NASA, a typical supernova creates enoug... | [
"This is probably a question without an answer.",
"It can depend on these two factors:",
"Stellar nursery where the Sun was created.",
"How many Population I, II, and III stars had created the Nursery.(If was just one , Population III star, then there's your answer.)",
"What type of stars were created near... |
[
"Does an empty refrigerator consume more power than a full one?"
] | [
false
] | My fridge is often nearly empty, so I got to wondering if filling it with a bunch of bottles of water would help keep it cool longer and thus increasing the time between cooling cycles, or if it simply doesn't matter what's in it. | [
"The power consumption is dependent on a number of things, but in this case, you're really only concerned with how much heat is lost to the environment.",
"Your suspicion is correct: If you open and close the refrigerator frequently, and it's empty, the cool air can quickly escape, making the fridge do more work ... | [
"While correct, it might take a long time to pay off. Let's say a typical empty fridge has 400 liters of space in it and operates at 3°C in a 23°C room. Assume that opening it briefly causes half of the cold air inside (200 liters) to be replaced with warm room air. Approximating the density of air as 1.25 kg/m",
... | [
"Of course one would wonder why you would open and close an empty fridge very often."
] |
[
"Is there an evolutionary benefit to humans' complex sexual desires?"
] | [
false
] | [deleted] | [
"1) Don't look for adaptive consequences for every apparent \"trait\". Just because it's something humans do doesn't mean that they were shaped to do that by evolution because it improves their fitness.",
"2) See the ",
"bonobo chimp",
", our closest living relative, whose entire way of life is based on the f... | [
"Less of a \"reason\" and more of a consequence of having a large brain/complex society."
] | [
"Just wanted to add that dolphins will engage in sex across species. They just enjoy sex. Evolution of a drive to have sex resulted in it being pleasurable. Leading to more frequent sex, which originally served to increase the number of offspring. This would seem at a glance to have no fitness benefit. However... |
[
"Why does electricity always hum at a B-flat pitch?"
] | [
false
] | Whenever I pass a power plant or hear a lot of electricity running through my house, I always hear that pitch. Edit: To those asking, I am a musician. | [
"Electricity is run on an alternating current (AC) which reverses voltage in the pattern of a sine wave. In the US, the frequency of this alternating is 60 Hz, which is a B flat (more of a flat B or sharp B flat, really). Sometimes interactions with surroundings, especially at high voltages like in transformers, ca... | [
"Good answer! To expand on this, in the industry we call it \"60 cycle hum\": Electrical current flow creates a magnetic field, and transformers have cores made of ferrous metal. So the changing alternating-current is causing the big metal cores to move a little bit in a way that matches the rate at which the cur... | [
"In the US, alternating current (AC) oscillates at 60Hz and the buzzing you hear is generated by the second harmonic, so 120Hz. The nearest B-flat is at 116.54Hz, so it's pretty close! The next B is at 123.47Hz, so really you're hearing something that is very much in the middle of B and B-flat. If you were in Europ... |
[
"Is Wolff's law the reason that athletes usually have higher bone density, or is there another cause?"
] | [
false
] | So I've read somewhere that football players have stronger bones due to the nature of their sport. I've also heard a claim from various Muay Thai practitioners that Muay Thai can condition one's bones due to microfractures. The claim is that every time you do something like bumping your shin, a microfracture occurs. When the microfracture is healed, the bone is stronger(similar to muscle recovery). Is there any truth to this claim, and were there any studies done on this? | [
"Oooh goodie, a bone question! Finally, something that's my cup of tea.",
"It is absolutely true that loading bone makes it stronger. We tend to think of bones as inert and static things--basically giant hangers from which our muscles and organs hang. In fact, the truth is exactly the opposite--bones are very met... | [
"Thank you so much for the detailed response. So what would be a real world comparison between the two ways bones strengthen(you mentioned that microfractures are not generally how bones strengthen).",
"As it turns out, bone cells (ostecytes) can actually \"feel\" mechanical forces and respond to them. They do so... | [
"Could I deduce that this would mean that most athletes have stronger bones due to heavy lifting, as opposed to constantly subjecting their skeletal structure to non-injurious blunt trauma?",
"Well, be careful. Really, most athletes have stronger bones do to constantly subjecting their skeletal structure to high ... |
[
"Why do nuclear bombs make mushroom clouds?"
] | [
false
] | Is the famous mushroom cloud that follows a nuclear detonation unique to nuclear explosions? Is it just the sheer size and power of nuclear bombs that makes the mushroom cloud so visible and defined whereas other explosion simply don't have the power necessary to create such a distinct cloud? In either case, why is the "mushroom" the shape that the cloud takes? | [
"This is not unique to nuclear weapons. Any sufficiently large explosion will produce a mushroom cloud. This is because the explosion pushes air out of the blast area, but after the explosion the air rushes back in. This is what causes the dust and smoke brought on by the explosion to form into the mushroom sha... | [
"Fluid mechanics grad student here, to add a smidge.",
"Once the low pressure zone created by the hot gas equalizes (the void is \"filled\"), the upwelling stops. This is key to forming the mushroom. As the upwelling stops, a vortex ring is generated, whose strength is determined by the height of the plume. \nIf ... | [
"At the center of the nuclear blast is a particularly hot fireball which rises much faster than conventional explosions as well, and that pulls the dust up, which lengthens the \"stem\" of the mushroom and draws more ground-level air towards the base of the \"stem.\" The initial blast produces super-hot X-rays whic... |
[
"When you tag someone with a laser in a lasertag games, how does the gear knows who tag who ?"
] | [
false
] | I don’t understand quite well how you can manipulate a laser to transmit informations such as a username by shooting another player, knowing that there’s not a lot of parameters you can manipulate in a laser (amplitude, wavelength, etc) and that the lasergun is pretty cheap | [
"Generally the datastream is 8bit, RS232. ",
"RS232 is a physical layer which defines connectors, voltage levels, cable capacitance, etc. It does not specify the framing or formatting of the data stream. \"Asynchronous serial\" is the term for the general class of byte-oriented, start/stop-bit-framed clockless se... | [
"To elaborate on this answer, Frequency modulation(FM) or amplitude modulation(AM) can be done for any spectrum of electromagnetic radiation. Radio waves use this technology to transmit the data that you listen to in your car, but infrared and visible spectrum EM radiation can use this technique as well. Some radio... | [
"To elaborate on this answer, Frequency modulation(FM) or amplitude modulation(AM) can be done for any spectrum of electromagnetic radiation. Radio waves use this technology to transmit the data that you listen to in your car, but infrared and visible spectrum EM radiation can use this technique as well. Some radio... |
[
"For satellites such as the James Webb, what are the benefits of observing infrared light versus visible light?"
] | [
false
] | null | [
"It's just a totally different slice of the universe. In general, you get a better picture of dust and gas, rather than of stars. This is important for completing the \"life-cycle\" of stars and galaxies, and seeing how stars and black holes are fuelled. It particularly focuses on \"warm\" dust and gas, rather than... | [
"One reason why James Webb is focussed on infra red is that with modern adaptive optics, we can do excellent visible-light and near infra-red work from the ground. But far infra-red doesn't make it through the atmosphere, so we need space telescopes for it."
] | [
"The temperature of an object determines what wavelength of light it emits. If you are looking for visible light, you will only see objects that are 700K or hotter, so mostly stars. If you look for infrared light, you can see all objects warmer than 0K, which is everything."
] |
[
"Why is it so difficult for particle accelerators to increase in energy, seeing as you need about 10000000 Tev for ~one Joule?"
] | [
false
] | Couldn't we just pour an amount of energy measured in joules in, and see what happens? | [
"Couldn't we just pour an amount of energy measured in joules in, and see what happens?",
"Let me ask you the related question to illustrate the problem:",
"How?",
"How do you put one joule of energy into a particle? Do you have an answer? That's problem... neither does anyone else. The problem of energy tran... | [
"You're essentially asking about what limits the center of mass energy of colliders. In all colliders, particles are accelerated by an electric field. The problem is that the faster a particle goes, the least time it spends in the field, and so the least efficient the field is at accelerating. Colliders are therefo... | [
"\"Apart from all the other problems\" the effect of tides on CERN accelerators has been studied:",
"\"Effects of terrestrial tides on the LEP beam energy\" by L. Arnaudon et al., Nucl. Instr. Meth A 357, (1995) p 249.",
"http://dx.doi.org/10.1016/0168-9002(94)01526-0",
" (edit: doi links with parentheses bre... |
[
"How come earth is magnetic even though earth's core is above the Curie point (Temperature where nothing is magnetic) ?"
] | [
false
] | Does it have something to do with the pressure or something ? | [
"The Curie point refers to permanent magnetism, where half filled outer electron shells allow an atom to be magnetic. When the atoms in a substance are aligned such that their individual magnetic fields are in the same direction, the substance is magnetic (see ferromagnetism for more details). Above the Curie point... | [
"Are there any theories as to what it is about the rotation and convection that lead to the occasional flips in polarity?"
] | [
"My understanding of the current theories on the subject is that because of the existent magnetic field, most of the currents will produce fields in the same orientation. Occasionally, however, there'll be small disturbances for one reason or another. There are many potential causes, such as impact events, the coll... |
[
"How did Tesla's tower work?"
] | [
false
] | It pulled electricity from the atmosphere correct? Is that even possible? If so, why has no one continued work on it? | [
"There are problems though. Earth-resonance falls off above 20KHz, and essentially becomes useless above about 100KHz. Yet Wardenclyffe coil is too small to operate below these frequencies. Tesla's records show two interesting facts: his original plans were for a tower 3X larger than the one he built. When cost... | [
"It wasn't meant as a power generator. ",
"Check this out"
] | [
"I can answer this one!",
"Some people erroneously think it was just a simple high-voltage radio antenna. Basically a normal radio antenna but with power levels so high that a receiving antenna could generate useful power. You know how crystal radios can operate without a battery? Something like that, but scaled ... |
[
"What is the heaviest a single particle can be?"
] | [
false
] | null | [
"We don't know."
] | [
"Wouldn't there be some sort of limit where it would collapse in on itself? "
] | [
"There could be a limit, but we don't know what it would be."
] |
[
"Animals camouflage by mimicking their environment, but that’s in our visible spectrum. Does camouflage of certain creatures extend outside of our visible spectrum, and if so, how far?"
] | [
false
] | Follow up, are there camouflaged creatures that we don’t perceive as such, but are fully camouflaged in ultraviolet or infrared or even further? | [
"The question then would be, do predators rely on other forms of light, such as heat, to \"see\" prey? Snakes I believe can sense heat with their tongues. I'm sure most predators use smell to some extent to enhance their vison."
] | [
"Snakes actually have a special organ that detects heat. Its called a pit organ."
] | [
"Hence pit vipers?"
] |
[
"With mild temps and lack of snow this winter will there be an abnormal number of bugs in the spring?"
] | [
false
] | With the unseasonably warm temperatures and lack of snow in many places in the USA will that result in an abnormally high number of insects in the spring and summer? | [
"i dont know if harmony is the right word here. i would say that there is an equilibrium that nature is attempting to reach at all times. fluctuations in biological systems keep that balance slightly off which is actually good because it keeps the system running. think about it like a pendulum: if it is at equilibr... | [
"In general insects do best with stable winter temps. If the temperature fluctuates wildly during the season some insects may prematurely emerge from hibernation. Many insects have evolved protection against even the worst of winters. These protections (see: ",
"http://en.wikipedia.org/wiki/Insect_winter_ecology"... | [
"Does nature not have mechanisms to tune itself to create an overall harmony? For example, if there's a decline in the numbers of some species in one season (in this case, the one that prefers warmer winters), that creates comfortable environment for other species to thrive (like the lack of natural enemy or abunda... |
[
"Why is Ebola so lethal? Does it have the potential to wipe out a significant population of the planet?"
] | [
false
] | Became curious of the disease, as Ebola is now spreading in Nigeria. | [
"In short, Ebola preferentially infects endothelial cells and is highly cytotoxic to those cells. So once it is in the bloodstream, it damages the endothelial cells that line blood vessels, causing circulatory system damage (or failure) causing the characteristic rashes, bruising and bleeding. As of now, Ebola is n... | [
"Ebola is almost ",
" lethal to wipe out a significant part of the planet.",
"The epidemiological risk of an infection is determined by multiple factors - those most pertinent to Ebola are transmissibility and infective period.",
"Transmissibility is a composite of multiple different factors including vectors... | [
"In biology, one learns to never say absolute words like \"impossible\" or \"never\" or \"always\". However, evolution of airborne transmission of Ebola is extremely unlikely. While there are many enveloped viruses that infect humans (HIV, Hepatitis C, influenza, Ebola, West Nile and many more), efficient airborne ... |
[
"I have an old AM/FM clock radio sitting on my office desk. Does it consume less energy when the radio is turned off compared to when it's left on with the volume all the way down?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"Devices powered on draw power",
"The answer can be found with a Google/Wiki search. Please start there and come back with a more specific question."
] | [
"Sure, there's a difference. There's four major elements that draw power when you turn it on:",
"the power supply. Since no power supply is 100% efficient, it will leak some power, mostly in the form of heat. Usually accounts ~5-10% of power consumption (in losses).",
"the signal processing, all the way from t... | [
"No problem. You'll still find some more accurate information out there though."
] |
[
"Are the different regions of the brain physiologically different?"
] | [
false
] | [deleted] | [
"The answer would be \"both\": the cells are different, and the ways they are connected to each other are different.",
"Even in the cortex (you know, ",
"that wrinkled walnut-looking stuff",
" that you first imagine when you think about human brain): even in the cortex, although it looks pretty uniform at the... | [
"There is huge anatomic variation between neurons, as discovered by Golgi in using a silver based stain which completely fills a random population of cells. Some may have small soma (10 microns) with few projections, while others may be have large cell bodies (50 microns) with highly branching dendritic arbor. Othe... | [
"So is it individual cells performing functions or are they acting as a group and functioning altogether? Is there a very distinct line where one type of cells end and another type begins? "
] |
[
"Why do people have talents since birth?"
] | [
false
] | You know kids who have mad talent skills in art, singing, dancing, etc. Is talent transmitted somehow genetically? | [
"nobody has an answer i guess..."
] | [
"These talents are not from birth, although i do understand the point your making, i believe these children that are really talented from a very young age have simply practiced these skills very regularly (usually due to parenting)\nI'm sure there is someone out there who could give you a better answer with some so... | [
"yeah, that's what i'm saying... \nwhy some people can easily compose songs, while other can't, or draw paintings so easily, and so on.. i mean yeah, you can teach yourself, but you know this saying - \"i guess i just don't have the talent\"...\nso what's \"talent\"?"
] |
[
"Any doctors/medical students here? Why would just one leg feel tired for no apparent reason while laying in bed?"
] | [
false
] | I'm 25 and smoke a lot and never exercise but I'm starting to change that. My diet sucks but I'm not overweight (actually underweight). Anyway, I'm just now starting to exercise again after years of inactivity so that's not the reason it feels tired, it happened before I started again. I'll just be lying in bed and it will feel tired almost like I just exercised that leg (no burning or warmth, but close to that feeling). According to it doesn't sound at all like restless leg syndrome. | [
"That's pretty nonspecific...",
"How long has this been occurring?",
"Is it the whole leg, above the knee, below the knee, or just a specific portion?",
"You say \"tired\" or \"just exercised\"... Are talking as if it's totally spent, or is it more of a tightness/aching, or something else?",
"Basically, all... | [
"It's hard to explain. It's pretty much the entire leg. It feels almost totally spent, but not completely. No tightness or aching. No burning (like from lactic acid buildup after working out or whatever it is). Just like it's almost entirely spent and it's a little hard to move.",
"It doesn't feel heavy or anythi... | [
"Are you describing weakness?"
] |
[
"With the billions of gallons of fossil fuel, can we glean any interesting paleontological knowledge from them? Or is it all too “gobbled up”?"
] | [
false
] | null | [
"Paleontology is more of a coal thing. If you look at coal under a microscope you can often still see the details of long-dead land plants and grains of pollen. Sometimes there are larger fossils, and sometimes animals. Many coal towns have fossils on display as trophies.",
"As a result of coal mining and coal re... | [
"Wow... thanks so much! I learned a lot."
] | [
"To add: if you happen to live in coal country, you can often find some really cool plant fossils in mine tailings. I'm most familiar with the Mazon Creek / Braidwood area southwest of Chicago, where there are organized tours and areas with public access."
] |
[
"Why does general anesthesia not stop the heart?"
] | [
false
] | I just recently learned (well, realized -- it makes sense, I just never thought about it) that people stop breathing when under general anesthesia. Why does the same procedure not stop the heart? | [
"I must correct you.",
"Patients do not all receive paralytic agents. They are only used when necessary for the surgery or for the method of ventilation. ",
"I see this stated quite often for some reason. ",
"Furthermore it is incorrect to state that the heart is unaffected. Most general anaesthetics depress ... | [
"The ",
"mechanism of general anesthesia",
" is pretty mysterious - it is known that centrally acting anesthetics inhibit neuron firing in certain parts of the brain. Some of these do have a respiratory depressing effect in the brain, but most of the reason why the patient cannot breathe under general is the us... | [
"Yes, this is exactly the case. It is important to remember that in true brain death the patient also cannot breathe for themselves - without a ventilator, the heart muscle will quickly die as the muscle is very sensitive to anaerobic conditions and then the patient will also be dead by cardiopulmonary criteria as ... |
[
"Why are sexual side effects so common with antidepressants?"
] | [
false
] | My app won't let me submit without adding text, but see the title. | [
"Currently it isn't really known why",
"It also seems that the prevalence of these symptoms isn't very well known either. ",
"Initial studies found that such side effects were reported in less than 10% of patients. When doctors have specifically asked about treatment-emergent sexual difficulties, some have fou... | [
"This effect is multifactorial and not well understood. In general, it is not surprising that drugs which affect the way your neurons communicate could have sexual side effects given the complex interplay between your central and peripheral nervous system in arousal, erection, ejaculation/orgasm, etc., though this ... | [
"Serotonin inhibits dopamine. Dopamine is the reward neurotransmitter, so an increase in serotonin will decrease almost every part of the sexual response cycle.",
"From Our Sexuality Eleventh Edition by Robert Crooks and Karla Baur",
"In contrast to the facilitator impact of dopamine on sexual behavior, the neu... |
[
"There are reports of a tale of an Inuk making a knife out of shit and spit in deeply sub-zero temperatures and using it to butcher a dog, build a sleigh and flee. Is such a knife mechanically possible or is it a tall tale?"
] | [
false
] | link to the apocryphal tale here: Previous discussion of this story on TIL: I underline that the tale is from Inuit oral history, so it may have grown in the telling. Could such a knife hold an edge sufficient to kill, skin and butcher a dog? Could it be mechanically resilient enough to do the job the tale claims it did? Are the faeces necessary? Would not simply making a similar tool out of ice/snow and spit be just as effective (if true)? | [
"Shear rheological properties of fresh human faeces with different moisture content\n",
"http://www.scielo.org.za/pdf/wsa/v40n2/09.pdf"
] | [
"Solidification of water that has been mixed with a fibrous component will create a ",
" (e.g., like fiberglass or concrete), with emergent material properties that differ from those of its constituents.",
"For example, ",
"Pykrete",
" is a mixture of ice and sawdust, which is much stronger (and more resist... | [
"I was under the impression that he would have lived mainly off of seal meat, and blubber. Would that provide enough fiber to create a good composite, or would be more like frozen mud?"
] |
[
"When a wheel or anything circular spins really fast, why does it sometimes look like its spinning backwards and then spin forwards again?"
] | [
false
] | Video for reference edit: Thankyou Everyone for your responses, special shout out to for his link of a super helpful video with examples of what I'm trying to talk about | [
"This is known as the wagon-wheel effect. It is most commonly observed when viewing a video recording of a spinning wheel. In this case, it is a result of a strobe-like effect caused by the fact that a video is actually made up of a series of discrete frames.",
"It can also happen in real life viewing, though. In... | [
"Is it possible that the frequency of AC street lamps cause us to view the wagon-wheel effect at night in a manner similar to how it's created in videos? I had always just assumed that was the case."
] | [
"http://www.vinylengine.com/strobe-discs.shtml",
"Yes. Check out turntable strobe discs, a gadget from the days of vinyl.",
"The same effect can be very dangerous in workshops with rotating macinery. Lighting is typically powered from 2 or more phases of the electric supply, to minimize the effect. Circular saw... |
[
"Could you take a look at this link and tell me why he's wrong? (re: Darwinism and evolution)"
] | [
false
] | I'm an atheist, and I believe in evolution. However, because I'm not knowledgeable about the specifics of evolutionary biology, the fossil record, etc., I'm not good at evaluating or disputing claims by people on the fringe. I found this link by typing into Google, "Did humans have enough time to evolve." I was seeking a discussion on whether humans had enough time to evolve to such a high degree of sophistication, because intuitively, even millions upon millions of years just doesn't seem like enough time. However, I know that science isn't about intuition -- it's about facts. I'm not a troll or a secret supporter of this guy. I looked at another link of his and he's talking about alien intervention, kind of like that Discovery Channel show, so I realize he's on the fringe, and possibly has zero credibility. But regardless, are some of his points -- such as about the fossil record -- valid? | [
"False dichotomy.",
"Straw man.",
"Ditto. These aren't actually separate concepts in evolutionary biology, they're concepts made up by creationists who don't understand biology.",
"There's no 'missing link'",
"Did he just seriously claim that hominid fossils are actually bigfoot?",
"Yes he did.",
"He ke... | [
"There's no 'missing link'",
"I like the graph, but I'm surprised to see the Successful Black Man meme pic :)"
] | [
"I'd recommend reading an ",
" book on the subject. Dawkins has some good ones, like The Selfish Gene or The Greatest Show on Earth. Well, I've heard they're good. I haven't read them."
] |
[
"Why does Bismuth appear the way it does?"
] | [
false
] | Cross-post from , but why does bismuth look like ? I'm pretty sure it's gotta do with the structure of it and how light get's reflected/scattered, but what exactly would that structure "look like"? | [
"The colours you see are actually caused by an ",
"iridescent",
" oxide layer on the surface of the Bismuth. ",
"Edit: formatting "
] | [
"Right. The very thin layer of oxide on the surface acts just like a thin layer of oil on a puddle. The thickness of the layer is about one-quarter of the wavelength of visible light, and that leads to interference of different colors depending on the exact thickness and angle you look at it."
] | [
"I'm trying to use it in a painting/sculpture. I had a tiny piece of it and I was going to either embed it directly or take a tiny chisel to it or something. Unfortunately I cannot locate the bismuth, though I still have my other rocks I bought. I haven't a way to get back to that shop right noiw, so it's still on ... |
[
"What is happening to the coke *soda*?"
] | [
false
] | What is happening to the coke after milk is being added to it? is the fat being bonded with the syrup? Or is the bilk bonding with the water and the other ingredients being heavier being pushed the the bottom. Kinda perplexed at the moment. hopefully we can get a chemist in here. | [
"What is happening is ,the fat in milk in in balls (casein)where the outside is hydrophillic and the inside is hydrophobic. Coke has a low pH level. When the milk is put in the low pH environment, the hydrophillic parts of the casein molecule get removed and dissolved, the hydrophobic fat molecules want to limit e... | [
"I don't know for sure, but I would guess that the artificial coloring bonds to the fat globs, pulling all the color to the bottom"
] | [
"What is causing the clarifying effect in the soda though?"
] |
[
"Which transfers more heat to the mug, microwaving a 1/2 cup of water for a minute, or microwaving 1 cup for a minute?"
] | [
false
] | When I make coffee, I usually like to preheat the mug (to keep the coffee warm for longer) by filling it about halfway with water and microwaving it for a minute. This can usually raise the temperature of the water in the mug to about 85-90C, and the mug absorbs some of that heat. Would I be better off microwaving a full mug? The water's temperature would be far lower, which means a smaller heat gradient, but there would be more surface area for the heat transfer to occur. | [
"It is the other way around. The amount of heat your water in the mug receives, depends on your microwave's MHz radiation. The higher the radiation intensity is, the faster water heats up.",
"However, heat transfer rate remains constant with more or less water. Since a microwave's emissivity of electromagnetic wa... | [
"If you could get a full mug also to 80-90 degrees in the same time, then the mug would be hotter in that case. If instead the full mug only got to 60 degrees, the mug would be cooler.",
"Depends on your microwave power settings. In general, if you put more of the hot thing in the mug, the mug will heat up faster... | [
"This question really got me thinking about transfer of energy. In theory I would have thought the cup would heat up faster without the water because there are less particles in the cup than there would be with the cup and the water so the particles with just the cup would be absorbing all of the microwave energy w... |
[
"Do humans emit X-rays from blackbody radiation?"
] | [
false
] | Infrared is the most well-known light emitted by humans, but what about the other frequencies of light? It seems by that there should be some–albeit a tiny amount–of every frequency emitted, but is this actually the case? | [
"I can't do the math right now, but you could calculate the energy emitted per second at your chosen frequency and then divide by the energy of a photon of that frequency; that should give an estimate of the rate at which photons are emitted.",
"Edit: I did the math. Taking the range of frequencies to be from 10"... | [
"Theoretically yes, but the intensity would be infinitessimally low. It would require a multiple order anti-Stokes shift where multiple atoms simultaneously combine their energy states and then release that energy as a single photon. The cross section of such an interaction is extremely tiny which leads to its ex... | [
"No, I didn't, but it's not gonna matter. What is gonna be, 100 orders of magnitude? Schroeder talks in his thermo book about very large numbers: you can multiply them by ordinary numbers and they stay about the same."
] |
[
"When did people realize that a whip crack was breaking the sound barrier? What did people think was causing that sound before then?"
] | [
false
] | null | [
"It was hypothesised in 1905 and proven by work in 1927 and 1958, including using photographic techniques to reveal the shockwave in the air (a ",
" ). More recently high-speed photography has allowed the whip's speed to be directly measured.",
"http://mathfaculty.fullerton.edu/tmcmillen/papers/2002-PRL(whip).p... | [
"In 1677, Sir Francis North published ",
"A Philosophical Essay on Musick",
", where he hypothesized that sound is transmitted by vibration or force, and that a whipcrack was caused by air molecules rushing in to refill a vacuum. ",
"By this time, a rudimentary form of atomic theory was spreading in acceptanc... | [
"We had detected sonic booms earlier in whips and rockets, but it became an actual problem when dive bombers shortly before and during WWII got fast enough for their props to break the sound barrier during steep dives.",
"Since the propeller tips are only briefly above the sound barrier, this creates a serious vi... |
[
"How do we measure extremely low or extremely high temperatures?"
] | [
false
] | Normal thermometers are using the expansion of fluids but at extreme low temperatures, most fluids become solid and at extremely high temperatures, they will vaporize. Does it has anything to do with the different energy levels of the particles? And if so, how do we measure distant objects like the sun or the Pluto? Edit: Far objects are measured by their thermal radiation. Cold objects are explained . Thanks for the answers! | [
"Let me speak to how extremely cold temperatures are measured.\nI'm assuming you mean cold things like Bose-Einstein Condensates and things as cold as the ",
"current record",
" of 0.000 000 000 1 degrees above the absolute zero.",
" ",
"Temperature is a measure of the energy content of matter. The energy t... | [
"The basic problem encountered with measuring temperatures at both extreme low and extreme high limits is the requirement to link the measurement back to the unit definition of the kelvin. That means something has to be referenced to a measurement at the ",
"water triple point",
", or 273.16 K. In practice, the... | [
"For objects a long way away (or objects so hot that no material could survive) I believe it's almost exclusively done by measuring thermal radiation, as already mentioned. You obviously already know about fluid-expansion thermometers. Some methods of temperature measurement include: ",
"resistance thermometers... |
[
"Why do teeth have nerves?"
] | [
false
] | If they are only needed to help chew food, and we do not really feel anything through them, why then? | [
"You need teeth. Nerves preserve teeth. \n* If teeth had no nerves, you'd chomp on unchompable things -- \"me eat rock\" -- until your teeth wore down, broke, and fell out. Then you'd die and not have children whose teeth have no nerves.\n* If your teeth have nerves, you're a bit more careful about your teeth -- \"... | [
"Take care of your teeth and you'll get laid. So many still don't understand this concept."
] | [
"For the same reason we have nerves anywhere else in the body: to signal, through pain, when something is wrong (infection, trauma, etc.) It used to be thought that people with leprosy had super human strength. But one day a doctor who lived in a leper colony to care for them asked a patient to get a stuck sink val... |
[
"Why are felines/cats generally afraid of water?"
] | [
false
] | I find it interesting that despite having roughly the same physical attributes as a dog/fox/wolf etc, felines are afraid of water (whereas those I mentioned cant seem to get enough), despite having roughly the same body type. Why is this? | [
"Unfamiliarity.",
"Wild felines generally have no problem with swimming, and domestic cats can be accustomed to water and learn to enjoy it as well.",
"Evidence:",
"http://www.youtube.com/watch?v=RvgsrT8Z924",
" ",
"http://www.youtube.com/watch?v=_5EjgCHLBDA"
] | [
"Is that genetic? If so, how were dogs familiar with it in their genetic past?"
] | [
"I doubt it's genetic... what I meant by \"unfamiliarity\" is that domestic cats usually aren't exposed to water when young, and don't know that it won't hurt them or that they can swim."
] |
[
"Where do neutrons come from? If the whole universe started as hydrogen which is just a proton and an electron, where did the neutrons come from when they fused into heavier elements?"
] | [
false
] | null | [
"After the Big Bang, the universe eventually cooled enough for quarks to form bound hadrons. Protons and neutrons both would've been produced as a result.",
"Protons are stable (as far as we know), but free neutrons decay with a half-life on the order of ten minutes. So any neutrons produced during this process w... | [
"At these temperatures the electrons are very detached. In plasma the electrons have been knocked off by the violence of the environment and are not bound to anything for now, although they are usually still nearby.",
"Also, the extra electron created in beta minus decay of a neutron into a proton will be moving ... | [
"I misspoke. Diprotons undergo beta plus decay, not beta minus. Charge is conserved here."
] |
[
"What will be used as a substitute for helium?"
] | [
false
] | null | [
"Helium in the atmosphere is slowly leaking into space and it is not easy to recover. There is a lot of He still in natural gas deposits so I expect when He prices get driven way up we will see companies that extract natural gas start separating and selling He. The government may stockpile again, but it seems like ... | [
"As far as lighter than air gases, there aren't many that are lighter than air and are also safe to use like helium. ",
"At least that I can think of off the top of my head. "
] | [
"The only reason the U.S. Government is selling off its helium reserves is because it's expensive to store. There's still plenty of helium in natural gas deposits; it's just not being extracted and sold because helium from the Government is still a lot cheaper. Once the government doesn't have any more helium, mi... |
[
"Is there any evidence humans lived with Neanderthals or other species?"
] | [
false
] | Since modern humans have Neanderthal DNA did any human settlements have multiple species living together do we have evidence such as bones? | [
"I don't know of any sites where there were human and Neanderthal bones found together, but they probably exist somewhere given the genetic evidence. However, Neanderthals and Denisovans were found together, along with hybrid children. See: ",
"https://www.nature.com/articles/s41586-018-0455-x"
] | [
"Yes, lots, since we have the entire Neanderthal genome. ",
"https://www.smithsonianmag.com/science-nature/neanderthal-and-human-matings-get-a-date-24217676/",
"https://www.smithsonianmag.com/smart-news/study-reveals-why-humans-dont-have-more-neanderthal-dna-180961047/"
] | [
"Wow that is extremely interesting thank you"
] |
[
"What’s the science behind japanese oil hardener product?"
] | [
false
] | I’m currently using a product from japan to dispose used oil properly. I am curious on the science behind it and have googled but i don’t think it is a result of hydrogenation. I can’t seem to find the ingredients of the japanese oil hardener in english so i can’t really tell what made my used cooking oil solidified after putting in the powder. | [
"You may be able to find a safety data sheet for the product which will may tell you outright what is in it, or at least have some clues. ",
"Can you describe the end result? My guess is a brownish, soft and oily gel. ",
"I suspect it is something very similar to ordinary flour, possibly a mix of powdered starc... | [
"Vegetable oil can under also harden under epoxidation, through oxidation and cross-linking. ",
"I imagine there are a view different ways to this, eg, peroxide and then some catalytic hardener to promote cross-linking, but I don’t know exactly what’s in yours. Can you give me a brand or something?"
] | [
"Hah, even simpler than I thought. I bet it's just a powdered high melting point fat, that when mixed with a low melting point fat combines to make a moderate melting point fat. That's funny."
] |
[
"When studies are suggesting that the Pfizer vaccine's efficacy drops after six months, how do they measure this?"
] | [
false
] | Are they looking at infections/severe illness in vaccinated people on a population level, or are they measuring the amount of antibodies people have 6+ months after getting the vaccine? Could it be the case that, although antibodies decline, B and T cells can still offer long lasting protection? | [
"Neutralizing antibodies titers- there is a study out of Israel (published in NEJM) - they studied health care workers and had neutralizing antibodies checked before the recent wave. Lower detectable Titers of neutralizing antibodies predicted who was at risk for infection despite vaccination.",
"sauce"
] | [
"I'd advise caution about this interpretation.",
"We expect antibody levels to drop to zero or background at some rate for any infection. Based on our knowledge of the immune system antibodies can only be a reasonable proxy in the short term at best.",
"Even then the Israel study is specifically saying there wa... | [
"You are correct. However, they found that titers were lower in those who got infected: in other words, as antibodies go down, risk of infection goes up. We don’t know what the B and T cells are doing, but at this point it looks like antibody levels are a decent proxy for overall immunity."
] |
[
"Why does tupperware get those weird white spots? Once the spots appear, is it still safe to use?"
] | [
false
] | I think everyone who's ever used tupperware knows what I'm talking about -- those that appear. Anecdotally, it seems to be related to washing or microwaving. So what causes them? Is this a physical change and/or a chemical change? And does anything about their appearance signal some kind of phenomenon that might make them unsafe for use? | [
"It is unlikely that it is a chemical change. Tupperware is made from mixtures of polyethylene and polypropylene, which inert to most conditions that you could make in your kitchen. However, you may know that if you heat Tupperware, that it becomes softer, and at highly elevated temperatures, may melt. What is most... | [
"Its more then likley the plastics getting near its melting temp. Nothing you can do to fix it but it should still be safe to use. ",
"On a related note, Tupperware has a lifetime warnty, go to google find a local tupperware lady (or man) and ask to have them replaced. You shouldnt need a recipt. I know this isnt... | [
"i'm not a scientist but I've got an uncle who has a plastic forming company and a father who worked with the huge Mixing / Melting machines they use. here is their reason: tiny bubbles form during the mixing process that get worked out during the \"rolling process\". the process turns the shapeless goo into a sort... |
[
"Can a black hole be charged enough to overpower it's gravity?"
] | [
false
] | Like for example say you have a negatively charged object of some sort, could you have a black hole with a charge strong enough that it would allow that object to escape once already inside it's horizon? EDIT: tried to make the question a little clearer | [
"Sort of.",
"A charged black hole is indeed \"more repulsive\" than an uncharged one. The electromagnetic field of the hole acts sort of like dark energy in cosmology and modifies spacetime to be repulsive.",
"So it is not directly the Lorentz force that pushes you out (a simple force cannot really save you fro... | [
"The information is already out. There is no need in EM to carry information about the total amount of charge at the speed of light. The field itself retains that information throughout space, in its shape.",
"Imagine charging a black hole by throwing electrons in it. An electron has field lines going out to infi... | [
"How can a black hole be said to be charged? Isn't any EM field information unable to get out?"
] |
[
"Why do metals interfere with lower frequency (VHF) radio transmissions moreso than higher frequency (UHF) transmissions?"
] | [
false
] | To visualize photons riding transverse waves (the transmission) through a dense field of particles (the metal), and given a common amplitude and rate of propagation, makes it seem VHF transmissions would have fewer chances of intersecting a scattering particle (proton/neutron/electron) than UHF. So, why do UHF transmissions penetrate metals better than VHF? Does it have something to do with their higher energy imparting something analogous to inertia that makes them fundamentally harder to deflect? | [
"There's no need to invoke photons at all. The metal functions as a ",
"Faraday cage",
", and that is well-described by classical electrodynamics. Holes in the metal function as high-pass filters, as in order to prevent the propagation of light through a gap, that gap must be markedly smaller than the wavelengt... | [
"Ah, I see.",
"To a good approximation in most materials EM waves interact in a linear fashion. That is to say that doubling the amplitude of the wave is equivalent to simply doubling any of its effects. So if your signal before interaction with the metal was has amplitude A1 and after interaction A2, then we can... | [
"Sincerely, that’s a great answer from a practical standpoint, and I thank you for it.",
"I also acknowledge that my description of photons “riding” waves of EM radiation was somewhat ham-fisted.",
"What I really was interested in, though, was an explanation of the physics. I.e., what are the specific interact... |
[
"Honest question about the vaccine?"
] | [
false
] | null | [
"The question is removed because it’s off-topic. If you continue to try to override the moderators’ decisions you’ll be banned from ",
"r/askscience",
"."
] | [
"Respectfully, I do not understand why it's off-topic. I'm asking for a scientific reason why we should all get vaccinated, as I'm unable to find an answer anywhere else.",
"I understand vaccination is good on a personal level for protection, but I'm asking ",
" why should I care if someone else does/doesn't ge... | [
"All of your premises are wrong. The vaccines prevent transmission and infection. To the limited extent your question reflects reality it’s been asked and answered many times."
] |
[
"When it rains/snows - how comes the rain/snow does not fall out of the clouds all at the same time?"
] | [
false
] | as title says - Question asked by my work colleague. Thanks. Edit: followup question - would there be any circumstances where the rain could eventually just fall all at the same time? Edit 2: thank you guys for the answers. | [
"It does. It's called sleet. If snow falls from a cloud and enters warmer air as it falls, some of the snow will melt as it descends. Larger flakes will remain partially frozen. The effect at ground level is you get big, soppy flakes of snow with drops of water falling at the same time.",
"For your second questi... | [
"Rain isn't ",
" the clouds, the clouds ",
" rain!",
"When each individual water droplet gets too big for air currents to support it begins to fall. This happens over time, and a little bit differently for each drop. Basically, as the cloud continues to condense more water, it makes more rain. Its not a fixed... | [
"A raindrop falls when it weighs more than the force of the updraft on it. Since the drops grow randomly as they bump into each other and the updraft in any given location is also changing randomly, the moment when any given raindrop reaches “critical fall mass” (my made-up term) will also vary randomly, and so the... |
[
"Is it possible to train your brain to have faster reaction times?"
] | [
false
] | null | [
"Call me out on this if I'm wrong, since I'm basing this on old information and fundamental neural mechanism.",
"At its core, reaction time can be broken down into a few components. Input to brain, processing and selection of response and finally signal that causes the response. For the first and the last, the ti... | [
"This doesn't cover improvement (it might come down to genetics), but here is data for the fastest of the fast:",
"http://www.ncbi.nlm.nih.gov/pubmed/22739331"
] | [
"Your reaction time to what? Regardless, yes, it's possible. One of the things to be aware of is that there's ultimately a trade-off between speed an accuracy, so past a certain point, your speed will improve, but you'll be false-alarming a lot as well. Video games are frequently used for this kind of training. ... |
[
"Does ice get harder as it gets colder?"
] | [
false
] | Does water ice get harder as it gets colder? For example, an article said ice on Titan is "rock hard" because of the tempetature. Is this accurate? | [
"Here's where we pull out our handy ",
"deformation mechanism map for water ice",
" (Fig. 19.26 ",
"here",
"). This tells us---not surprisingly---the dominant deformation mechanism for an arbitrary temperature and stress, and also provides the deformation (i.e., creep) rate. The grain (crystallite) size for... | [
"Yes, but I'm not sure how much.\nAssume a hydrogen bond takes a set amount of energy to break.\nAs you cool the ice further, you're removing vibrational energy from the water molecules, therefore putting less stress on the hydrogen bonds, therefore to meet the set energy required to break the bonds, you must apply... | [
"Yes, somewhat. Temperature history certainly affects grain size. For ice, though, I don't see a huge dependence on gran size for the topics discussed here: ",
"check it out yourself",
"."
] |
[
"[Physics] What type of detector would be needed to verify or disprove the existence of the gravitational wave background?"
] | [
false
] | The gravitational wave background is conjectured to exist and is similar to the cosmic microwave background radiation, but instead of light, it is gravitational waves. As light from the first quarter million years of the universe could not penetrate the plasma soup at the time, the CMBR is limited to showing us the universe after that time - the gravitational wave background might enable us to probe earlier than that. | [
"Would we ever be able to measure it? If we're looking for a gravitational wave background that's similar stylistically to the CMB, it's earliest surface would be at nucleosynthesis right? I would think that anything from that time period would be redshifted into oblivion.",
"The start of BBN was about ~0.1s post... | [
"There was a group in 2014 that claimed to had found GWB only to learn a lesson in peer reviewing.",
"I believe you're referring to the BICEP2 resuls, but I feel I should point out that had nothing to do with peer review (in fact the paper passed peer review and was published in PRL): the problem was that the dus... | [
"Please be civil. This is an educational subreddit. If you would like a source, please ask in a kind fashion. There are some great links in the sidebar on how to follow said suggestion. "
] |
[
"What drives the electric current in earth's core that is responsible for earth's magnetic field?"
] | [
false
] | I've searched high and low for a good paper or diagram that describes the current in the earth's core, but found nothing. We know it's there because it's necessary for a magnetic field, right? And unless the liquid core has a very positive or negative net charge, it is more than just the movement of the liquid itself. I hope I have the proper understanding, but please correct me if I'm wrong. If we know the magnetic field strengths at various places around the earth and at the same distance from the core, wouldn't it be possible to derive the location, structure and power of the electric current? | [
"Molten iron inside the earth is flowing. The flows are driven by convection (it's hotter at the center of the earth). This leads to the magnetic field.",
"More here ",
"http://www.usgs.gov/faq/?q=categories/9782/2738"
] | [
"Rotation of the ferrous core in the surrounding magma."
] | [
"Rotation of the ferrous core in the surrounding magma."
] |
[
"What dose the R [Random] in RAM [Randomly Accessible Memory] mean?"
] | [
false
] | Dose it mean, that it can be accesed at any [Random] moment, or that the any [Random] part can be accesed? Couldn't it have been AM [Accessible Memory] or FAM [Freely Accessible Memory]? What was the reason for the choice. | [
"The hard drive analogy is particular apt - before RAM, there was ",
"drum memory",
", which was a lot like a hard drive."
] | [
"The hard drive analogy is particular apt - before RAM, there was ",
"drum memory",
", which was a lot like a hard drive."
] | [
"The question has been answered already, but from a historical perspective a lot of the terminology we use today was coined in the age or punch and tape data storage. So, having a real random access was a pretty incredible thing. Being able to read memory by memory location instead of running through a long tape ... |
[
"What interesting occurrence of memory in nature did we observe?"
] | [
false
] | . . Epigenetics can retain information across generations. The immune system stores information about pathogens. Those are two examples beyond the brain I can come up with that I would apply the concept of memory to. Do you know of more? | [
"I'm very stupid, but excuse me for that and indulge me: I'm not following your leap of logic. How would you characterize the relationship between epigenetics and shape-memory alloys?"
] | [
"I don't have anything new, but since the context was fitting, I thought I'd share ",
"this research",
". ",
"tl;dr: Visit some wallabies isolated from predators for thousands of years, show them cut-outs of predators, watch wallabies get scared."
] | [
"the prevailing hypothesis about molecular origins of life postulates that informational polymers like RNA (or PNA or others) began a cycle of self-catalyzing its own formation. These pre-biopolymers have been shown experimentally to adapt to their environment (Ill dig up a reference) but more importantly, attain ... |
[
"How is it that if Earth exerts a force of gravity on you of 600N, then you also exert a force of gravity on Earth of 600N?"
] | [
false
] | null | [
"Could you elaborate on your question? That is, the question of \"how is this fact a fact\" is very difficult to answer with anything except \"well... that's the fact.\""
] | [
"The gravitational force is proportional to the product of the two masses involved. So the larger the mass that's pulling on you is, the stronger you are attracted because there is more stuff to pull. But also the more mass you have, the stronger you are pulled because there is more mass to be pulled on.",
"So ... | [
"I think what's confusing you here is a misinterpretation of the underlying meaning of Newton's third law. From a deep perspective, there aren't actually two independent forces involved. It isn't you pulling on the earth ",
" the earth pulling back. Rather, there is a single attractive force of 600N ",
" you... |
[
"Could a biologist/earth scientist please help me answer a question regarding plants asked by my ten-year old?"
] | [
false
] | Daughter: Dad - you said plants take water and air and transform it into plant matter? Smug dad: Quite right, little sunshine. Daughter: Well, that means the more plants there are, the less water there is, because they are using it up, turning it into something else... And so, one day, there cannot be any water left... right? Befuddled dad: Err, wait, that obviously cannot be right - hold that thought... (frantically tries to tackle the perceived paradox with common sense, finds he has none, but only half-truths, unfounded hypotheses, and more-than-half-forgotten high-school learning... Do plants return some water "when they are done"? Sweat/transpire? But some water would still be locked up in the new molecules of plant matter, no? Do the plants give it back after they die? Or is there so much water and so little plant material globally that it does not matter? Am I wrong and plants actually build themselves from air, using water only as a "catalyst"? And how do I dare to throw around big-boy words like "catalyst" when I cannot even answer a kiddie question about water?) Daughter: Dad? Dad: Don't worry, little buttercup, I'll ask the Internet, after the weekend... there is this cool forum, you know - ... Daughter: OK, let me know when you hear back from them! Dad (to himself): oooo, and I have a second question for those scientists as well.... Question 1: Plants, in my understanding, use up water and air to make more plant matter. Does this mean that their consumption of water is permanently removed from the water cycle? Question 2: In your view as scientists, how dangerous/problematic is it that "we" (i.e., parents with only a basic education in the natural sciences, but enough of useless other education to consider ourselves, vainly, "fairly educated") feed the next generation with our own falsehoods and misunderstandings from our privileged position of perceived authority figures? All this "teaching" about how the Earth and the ecosystems work, what atoms look like, how traits are inherited, how our bodies handle diseases... surely it is 60% wrong on a good day? I used to think how horrible it is that creationists teach their kids all these blatant falsehoods... but suddenly I am not so sure those parents who are accepting of science (but otherwise not well-versed in it) are any better. Thoughts? | [
"Plants also have to break down energy via respiration, which yields water as the final product."
] | [
"Not only do plants have to undergo respiration, when animals metabolize sugars, we generate water as the by-product as well. That's how the water cycle is completed.",
"I think the most important lesson parents have to instill to their children is to ",
" if their answers are correct. Beyond giving the best an... | [
"The best thing any privileged authority figure ever did for me in teaching science was to lift the curtain and demystify what knowledge authority really is and isn't.",
"Science is often thought of as a large collection of useful facts, but in truth it's not (just that). Science is the attitude and technique tha... |
[
"How much virus is 10 TCID50?"
] | [
false
] | null | [
"Did you check this article: ",
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7973348/",
"? It has a lot of math, but the gist is that 1 TCID50 is the amount of virus needed to infect half of a tissue sample, so 10 TCID50 is 10 times that viral load"
] | [
"The TCID50 is a way of measuring the amount of virus present in a sample, and 10 TCID50 means that if you take a sample and dilute it by a factor of 1,000,000,000 (10^10) only half of the cells that are exposed to the diluted sample will be infected. It's a laboratory measurement that's used to compare the infecti... | [
"the amount of virus needed to infect 50% of the cells in tissue culture",
"Wait . . . I thought it was the amount needed to inoculate a flask of cells, in order to have a 50% chance of causing an infection (i.e. infecting at least one cell). Can you double check this?"
] |
[
"How does a permanent magnet attract ferromagnetic materials."
] | [
false
] | null | [
"Rat_poison answers the B and H question really well, so I'm going to answer your first question.",
"Ferromagnetic materials are magnets. a permanent magnet is a piece of ferromagnetic material that we have oriented all the domains (mostly) into the same direction. So all the individual magnet dipoles in the ferr... | [
"nth EDIT: Would the person who downvoted please explain the reason? I think I'm right and if I'm wrong I'd like to be corrected.",
"Magnetic monopoles have nothing to do with Maxwell's equations.\nTheir inexistence isn't something theory deduces. It's based on observation alone. In fact it works the other way ar... | [
"Do you mean a paramagnetic material, where there are randomized, permanent dipoles? Ferro and ferrimagnetic materials do possess an overall magnetization vector. ",
"When a paramagnetic material is placed in an external magnetic field, because each unit does have a dipole, the crystal structures begin to orient ... |
[
"How is the observer effect consistent with quantum tunneling?"
] | [
false
] | The quantum observer effect has always been the part of QM that's hardest to wrap my head around. I was thinking about this and it raised the following. This is almost certainly a gap in my understanding of quantum mechanics, but I'll throw the question out there: if we can see macroscopic effects of quantum tunneling in say computer transistors, that seems like it'd be sufficient to count as observation of the electrons. But descriptions I've read of the observer effect seem to indicate that the wave-like properties of electrons should go away when they are observed, making quantum tunneling impossible. I'm sure I'm missing something, but what is it? | [
"An electron tunneling a new nanometers is not a macroscopic effect in itself. The result of it can have macroscopic effects, such as your electronics don't work. But those happen after the electron is measured on the other side of the barrier and tunneling has taken place. "
] | [
"In basic quantum mechanics there are two major elements of the physics: (1) a ",
" part, where you have a wave function that evolves (according to a certain wave equation -- Schrödinger's Equation or the Dirac Equation or whatever) in a time-reversible way; and (2) a ",
" part, where the wave function \"colla... | [
"If a potential barrier is thin enough, an electron has a nonzero probability of being located on the \"other\" side. (By \"other\" we mean the side that is prohibited in classical mechanics.) Once we measure the electron to be on the \"other\" side, it actually is there.",
"It's not like how you are describing i... |
[
"Can humans make sounds that we cannot hear? What about other species?"
] | [
false
] | null | [
"I believe that he is asking is humans are able to create sounds that are outside this range. I would have to go with no on this as there would be no real need for humans to be able to make these sounds if we cannot hear them and so we have developed to a specific range. The typical human vocal range for males is 8... | [
"on the second question, i think op means as it applies to that species. are there any species which can produce sounds that they cannot hear themselves"
] | [
"Of course. Hold your arm out in front of you and waggle a finger around. This makes a sound. Can you hear it? No, because it's too quiet for you to hear. If you mean can we make a sound that is too low- or high-pitched to hear, then again, the answer is yes. Waggle your finger backwards and forwards once a second.... |
[
"Was there any evolutionary advantage behind the widespread use of salt on cooked food? Or is it just because we got used to the taste?"
] | [
false
] | null | [
"Salt, drying, and freezing are the three food preservation methods that humans have had access to for thousands of years. Freezing isn't always available outside of cold climates, and drying can run the risk of other animals getting to the food before having the chance to eat it. ",
"Salt, however, is extremely ... | [
"In addition to ignorant's comment...",
"Salt used to be very hard to come by for our ancestors, yet it is essential to be in our diet (mainly the Na/K pump and osmoregulation). Making it taste good got our ancestors to actively seek salt in their diet.",
"Monkeys still do this too. They have a diet of mainly f... | [
"Don't forget sugar, oil, and vinegar as natural preservatives in your list. "
] |
[
"How is data stored in huge data centres, like the Google Drive storages? Are they like the discs in hard drives but giant? Do they use discs at all?"
] | [
false
] | null | [
"Google has published statistics about hard drive failures",
" because they use so many of them.",
"In particle physics we use a mixture of hard drives (recent/frequently accessed data) and tapes (cheaper per terabyte, but accessing data can take hours or even days - for long-term storage), but we \"only\" have... | [
"One of the better references here is Backblaze, because unlike Google etc, they are completely open about their large amount of storage.",
"https://www.backblaze.com/b2/storage-pod.html",
"It's worth noting their performance needs are much lower than, for example, any databases used by Google. Facebook has a l... | [
"Rare events and analyses that need large data samples.",
"Raw events in ATLAS and CMS are of the order of 1 MB, it depends on what's happening in the event of course. There are collisions every ~30 ns during data-taking, if every collision would be stored we would get ~30 TB per second or ~200 exabyte per year a... |
[
"What is the physiological basis (and evolutionary significance) of itches, and why does scratching relieve them?"
] | [
false
] | [deleted] | [
"Wikipedia has a pretty reasonable article on itch.",
"The gist of it is that relatively recently, we found out, \"oh hey, there are actually specific receptive pathways for itch.\" For some reason, which never made sense to me personally, people had thought for a fair amount of time that itch was sensed by pain ... | [
"Danharaj offered a dubious, extremely simplified explanation with no sources or credentials. Itching is most likely much more complex than that.",
"I wouldn't trust him on this. "
] | [
"I can't speak to the evolutionary basis of itching, but ",
"this paper",
" came out a while ago, along with its ",
"sciencedaily commentary",
" if you can't access Nature Neuroscience.",
"tl;dr: There are sensory neurons in your skin that fire in response to histamine, which is released by inflammation a... |
[
"When someone loses one of their five senses, does the brain actually change to make the others better or is it just a result of getting used to it?"
] | [
false
] | null | [
"I believe you are both right and wrong. Getting used to something means the brain has changed in some way.",
"It's common for brain areas that were previously associated with one of the senses (such as vision) to be used by other senses after the loss of that one. Blind patients often use the visual cortex to pr... | [
"I believe you are both right and wrong. Getting used to something means the brain has changed in some way.",
"It's common for brain areas that were previously associated with one of the senses (such as vision) to be used by other senses after the loss of that one. Blind patients often use the visual cortex to pr... | [
"I think, when discussing neuroscience, it's always important to emphasize that learning and other psychological changes are also neurological changes. There are people who don't really understand that or think about it that way. But, I also wanted to put out that the usage of different areas of the cortex in actua... |
[
"How much of a difference in DNA is there between the average first world person and a completely isolated tribesman in South America?"
] | [
false
] | Or is there a different, more significant biological difference? | [
"This is both wrong and a really unhelpful way to think about genetic differences between organisms.",
"Take chimps, who are much, much closer to us than rats. For the genes which we share there is about a 1% difference in the sequences of those. But humans have somewhere around 1500 more genes than Chimps which ... | [
"This is both wrong and a really unhelpful way to think about genetic differences between organisms.",
"Take chimps, who are much, much closer to us than rats. For the genes which we share there is about a 1% difference in the sequences of those. But humans have somewhere around 1500 more genes than Chimps which ... | [
"This is both wrong and a really unhelpful way to think about genetic differences between organisms.",
"Take chimps, who are much, much closer to us than rats. For the genes which we share there is about a 1% difference in the sequences of those. But humans have somewhere around 1500 more genes than Chimps which ... |
[
"What two species are the most distant relatives that can still produce an offspring?"
] | [
false
] | null | [
"I dunno if it's the ",
" distant, but the wholphin (a ",
" hybrid between a dolphin and a false killer whale) should at least get some mention. ",
"http://en.wikipedia.org/wiki/Wholphin"
] | [
"Two different species of animal cannot, by definition, have fertile offspring.",
"Ursid hybrids (offspring of different species of bears)",
" are often fertile."
] | [
"Wouldn't the fact that the offspring is fertile indicate that the dolphin and the whale are actually distant members of the same species? "
] |
[
"Do butterflies imitate the falling leaves?"
] | [
false
] | Today I saw a leaf spinning mid-air and the first thought was that it was a butterfly. Is it possible that butterflies evolved that way to imitate the falling leaves and escape the predators? | [
"As discussed in the research paper below, the fluttering pattern of butterfly wings does appear to be an adaption to avoid predatory birds since butterflies are active during the day. Likewise, fluttering by moths which are active at night would be adaptive to help escape bat predators. Some butterflies such as ... | [
"I think that this sounds like a no on OP's question, though, which was whether flying butterflies mimic falling leaves. On the contrary, the authors of this study propose that butterflies have evolved to stand out against the background:",
"A bird, we suggest, could learn or inherently know that brightly colored... | [
"Interesting. Thanks!"
] |
[
"Are we the only species to use currency?"
] | [
false
] | null | [
"Hi DannyRoy4 thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the follo... | [
"‘Anthropology’"
] | [
"Anthropology "
] |
[
"Why do matter and anti-matter produce energy when they touch?"
] | [
false
] | null | [
"\"Why\" is a sort of generalized question. Do you mean \"what is the reason behind?\" or do you mean \"What is the processes by which it happens?\" ",
"From ",
"wikipedia's article titled Annihilation",
"Since energy and momentum must be conserved, the particles are simply transformed into new particles. Th... | [
"Remember that energy is mass and energy is conserved. But a lot of other things are also conserved in physics like electric charge and various quantum numbers like baryon number, lepton number, etc. Normally you don't see particles undergoing reactions that involve changing to very different particles (such as, sa... | [
"They produce photons with kinetic energy, the energy was always there."
] |
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