title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Are capital goods included in the calculation of GDP every year?"
] | [
false
] | Say I invested 500$ in a machine in year 2012-2013 and that machine is still running in the year 2013-2014. Will this 500$ be added for the fiscal year 2013-2014 GDP? Also, what about inventory? | [
"There are two ways of thinking about GDP and both ways have to be equivalent in the end as they are measuring the same thing. In Brazil your example, you've confused the two different ways.",
"Your earlier question stemmed from the difference between ",
" and ",
" in economics. The value of an existing capit... | [
"No, GDP, the gross domestic product is the increase of production at a given time or period. \nGDP only aggregates what is produced/consumed so capital and and inventory aren't concerned. What you have are the differences of those variables. Inventory and capital would matter in the measurements if they had change... | [
"Thanks for the quick reply! If I could I would like to ask a follow up question. ",
"If I buy a product from Brazil ( assume I live in USA) that does not factor into the reduction due to import, right? My reasoning is that the good wasn't produced in USA, hence its import shouldn't be subtracted from GDP. If my ... |
[
"Why do we perceive red as running into violet on a color wheel if their light frequencies don't similarly run into each other on the light spectrum? [neuroscience]"
] | [
false
] | For all other colors that bleed into each other on a color wheel, there is a corresponding "bleeding together" of frequencies on the light spectrum. Why do we perceive color in this way? Would this be the case if the visible light spectrum was a different stretch of the light spectrum, for example if we could see only between yellow and blue, or infrared and ultraviolet? Please let me know if it's unclear what I'm asking. I also was unsure whether to tag this in neuroscience, biology, or physics. | [
"Color perception is a bit complicated, but essentially, our eyes don't detect color in the same way an instrument would. An instrument takes the light and disperses it into its component colors, like prism. It then measures where there is a strong intensity on the detector. If there is only red light, the detect... | [
"I'm not sure if bringing up the opponent process stage adds much to the explanation that violet light is the result of activating S and L cones at the same time. But the opposite color pairs your eyes detect are ",
"magenta-green and blue-yellow",
". They detect these color pairs through Cg cells and Cb cells ... | [
"The tricky part about what you are asking is that \"violet\" is used to describe a range of colors. Your eyes have three cones - S, M, and L. We think of these as Blue, Red, and Green but the match up isn't perfect to the way these colors are used everyday. In particular, many people would consider the shortest wa... |
[
"How are photons in light bent by stars if they don't interact with the higgs field?"
] | [
false
] | They must not interact with the higgs field, by my assumption, because they have no mass... but Einstein proved that light is affected by gravity, so how does that interaction work? | [
"They must not interact with the higgs field, by my assumption, because they have no mass",
"That's correct, at least insofar as one can make such statements in a non-mathematical way.",
"but Einstein proved that light is affected by gravity, so how does that interaction work?",
"Einstein's reformulation of g... | [
"Yes, that. I would also add that the Higgs field has nothing to do with gravity."
] | [
"No no no. It's ",
" that curves spacetime. (And pressure, stress, and momentum, but you can usually ignore those.) Whether that energy happens to be intrinsic energy, a.k.a. mass energy, caused by the Higgs mechanism, or some other kind of energy, it doesn't matter."
] |
[
"Is there a tolerance band of possible values for the Law of Gravity? e.g. F = GmM•r^(2 +/- 0.00000000000000001)??"
] | [
false
] | I know the theory says that the exponent is 2, and that all experiments are consistent with it being 2, but is there anything that shows it must be precisely 2 as opposed to (say) 1.99999999999999999999998? | [
"You can show that it's two by assuming Poisson's law and knowing that we have three dimensions.",
"However, general relativity has some deviations from the inverse square law."
] | [
"Out of my field as well, but isn't the R",
" a function of the fact that fields are proportional to area, which is a mathematical function of R squared? Thats the way it works with electrics I believe.",
"Of course there are uncertainties in the other parameters."
] | [
"The experimental limits are length dependent. The most interesting are the short length scale limits because they put limits on the theories with extra-dimensions. Have a look at preprint below.",
"http://arxiv.org/pdf/hep-ph/0303057v2.pdf"
] |
[
"Are underground water turbines closed systems?"
] | [
false
] | I know you've got a lower lake and an upper lake; the water cascading down into the lower lake during high demand generates electricity. But what does it actually look like? Is the water in a great tube, or does it flow freely? | [
"Does this help?",
"http://www.tepco.co.jp/en/challenge/energy/images/16-01.jpg",
"I'm not sure exactly the context of your question, but there's no air in a generator turbine system under normal conditions. If you are imagining some kind of old-timey water wheel in there or something, it's not quite like that... | [
"Hey thanks for your reply. I'm wondering for a book -- the whole context is, could a character sneak into a city through an underground power system in an abandoned mine? Would you maybe come out in an underground building that's kind of like an office if you snuck through old mine tunnels towards what's being use... | [
"Trying to joyride through a working turbine wound invariably be fatal in the real world."
] |
[
"How did birds evolve from dinosaurs if their extinction was so abrupt?"
] | [
false
] | I don't question that birds did evolve from dinosaurs as even with my very limited knowledge I can see the similarities, but how, since the evolutionary process takes a very long time did this happen? since most theory's about the dinosaurs extinction imply that they all died out in a very short period of time, how was their DNA able to be passed on and share similar traits with modern day species of birds? | [
"To further elaborate on other posts, modern day birds are part of a group of dinosaurs called the ",
"theropods",
".",
"\"Among the features linking theropod dinosaurs to birds are the three-toed foot, a furcula (wishbone), air-filled bones and (in some cases) feathers and brooding of the eggs.\"",
"If you... | [
"Humans are apes, I think you meant humans did not evolve from chimpanzees."
] | [
"All dinosaurs did not die at the same time. There are 335 kinds known so far from 165 million years, and no one kind lived for more than two million years or so. The only reason we think of dinosaurs as going extinct at one time, 65 million years ago, is that this last group of dinosaurs didn't get replaced later ... |
[
"Is there an absolute maximum value for a magnetic field?"
] | [
false
] | Is there a value of Amps per square meter that can not be exceeded? Or is it (theoretically) possible to have an infinite amount of Amps/m2? | [
"To my knowledge, there is no fundamental limit to the strength of a magnetic field. With that said, literal \"infinities\" do not exist in the physical world. It would take more material/energy than is present in the observable universe, and longer than the universe has existed, to make a magnetic field that is li... | [
"Yes. The energy density of an electromagnetic field is proportional to the square of the magnetic field strength (plus the square of the electric field strength). This is one of the terms in the Einstein field equations that govern the gravitational field, so, in principle, a sufficiently strong magnetic field c... | [
"I've heard of a ",
"maximum information density",
" which is related to the surface area of a black hole's event horizon. Is there a magnetic field density that would create a singularity? I imagine that would be an upper bound."
] |
[
"What would happen if a regular black hole collided with an antimatter black hole?"
] | [
false
] | null | [
"There’s no distinction between a “normal” black hole and an “antimatter” black hole. Black holes are characterized by three parameters only: mass, angular momentum, and electric charge. They don’t come with labels saying that they were made by matter or antimatter. A black hole is a black hole, no matter what’s go... | [
"Strange, thank you. I have another question then. What would happen if antimatter was inserted into a black hole? Would it shrink? Or just become part of the larger black hole?"
] | [
"It would make the black hole a little bit bigger, just like regular matter."
] |
[
"What is the weak nuclear force?"
] | [
false
] | [deleted] | [
"So... a particle travels from A to B, both places we observe it at. But since we don't observe it between A and B, we can't know for sure exactly what path it takes. Some of these paths involve interacting with other \"particles\" in other fields. And when an \"interaction\" takes place, momentum is exchanged. Cha... | [
"Thanks for that link. I have been waiting for an article like that for years. I want to learn more about modern physics, but the laymen pop science books are a level or two beneath me, and I just don't have the time to go through a whole textbook or online course purely out of curiosity. If only this guy would wri... | [
"/u/shavera",
" has a much more comprehensive answers but for a ",
" simplified answer just remember the weak force is responsible for beta radioactive decay.",
"A neutron interacts via the weak force to decay into a proton, an electron and an anti electron neutrino ",
" ",
" ",
" ",
" ",
" ",
" "... |
[
"What are the benefits of our brain hemispheres controlling the opposite sides of our bodies?"
] | [
false
] | I understand that once when the fish saw a predator approaching, it needed to trigger the muscles on the other side of the body to flee, but what purpose does this design serve today? Would it be more efficient if each hemisphere controlled its side? Are there any creatures like that? | [
"While this is not an answer to your question, it will provide a way to ask a better question.",
"Your statement of opposite hemisphere control is a bit generalized. For larger functions, this is true in some cases, but hemispheres don't entirely work that way. There are ispilateral (same side) and contralateral ... | [
"Heres a related thread :) \n",
"http://www.reddit.com/r/askscience/comments/i1ggl/what_iswas_the_evolutionary_advantage_of_having/",
" "
] | [
"That makes sense. Thanks."
] |
[
"How to make an ice cube last for a long time using ordinary materials?"
] | [
false
] | Hi askscience. I'm helping my 10 year old daughter with a school project. She has been tasked with creating something in which to put an ice cube and make it last as long as possible. She has gotten up to 2 1/2 hours with three trials. Later this week the kids will be competing to see who's contraption works the best. I'd love to help her rock this one out, but frankly I don't have any particularly good ideas. The only rule is that it can't use commercially produced insulation materials. Please don't jump my case for "cheating" on a school project... that's not the case. The three experiments she completed are the graded school project. She has written up her report and that will be what she submits for grade. This is only for the fun, non graded competition at the end. | [
"I don't know if adding sawdust will remove any criteria of the assignment, but consider making Pykrete.",
"http://en.wikipedia.org/wiki/Pykrete"
] | [
"You might be able to approximate a vacuum flask. Take two glass jars with metal lids, one large and one small (such as a mayonnaise jar and a baby food jar.) You'll want to glue the lid of the small jar to the inside of the lid of the large jar so that it's suspended inside. However, don't just glue a metal lid... | [
"Aside from the vacuum flask idea already proposed, air is about as good an insulator as you could want. An airtight sealed cardboard box full of (pre-chilled) rolled-up newspaper would be pretty effective."
] |
[
"Are there more shooting stars near the equator?"
] | [
false
] | I'm currently staying with some friends on an Island in Indonesia, and we have been seeing a LOT of shooting stars. Two nights ago we saw a massive meteor that visibly broke up into sections, and I thought it was a one in a lifetime event. Then we saw a very similar one last night. I go camping/hiking in Australia quite often, so I spend a lot of time stargazing, and I have never even seen anything close to what I have seeb on the last two nights. Was it simply a coincidence, or is the incidence of meteors more common near the equator? Or are we passing through a comet's tail at the moment etc.? | [
"I can't think of anything that would cause more meteors at the equator, but I can think of something that would cause you to see more meteors in Indonesia than Australia--light pollution. If you're hiking or camping within an appreciable radius of a major city, your ability to see lights in the night sky is greatl... | [
"According to ",
"this",
" website the Orionids are right about now, although other sources are indicating that the shower is typically later. That may have contributed to a higher-than-average number of shooting stars. "
] | [
"I'm pretty sure it does--if you were floating in the middle of the Pacific on a perfectly clear moonless night I'm sure it would put all of our collective stargazing spots to shame. Once again: not an expert at all, but it's both my interpretation of this diagram and my personal experience."
] |
[
"How can you separate mixed dna samples?"
] | [
false
] | Every now and then, I have a memory from an old episode of Quantum Leap where Sam becomes a woman, and long story short, saves her son from being abducted by two men. At one point, the men discuss how if they both rape the boy, the authorities will be at a loss because the DNA would be mixed and impossible to identify. Obviously, this sounds like truth at the surface... but it's been close to a decade and half since that show aired (if not longer) and I can't imagine that it's true anymore. How do scientists identify who the culprits of a rape were when there have been multiple parties involved? Once DNA is mixed, be it blood or semen or anything else... how can science identify it with 100 certainty they aren't picking chromosomes from one person and chromosomes from another? | [
"They always have to do this to separate out the victim's DNA. Adding one extra isn't too tough - if you know there are two perpetrators, they test quite a bit of DNA and can get 3 different results. In a large gang rape, it gets increasingly difficult, but apparently is improving. Here's an interesting article on ... | [
"If you read further into a process referred to as STR profiling, it is a method that is used by forensic scientists to determine if a sample contains a mix of two or more DNA types. It basically involves the amplification of specific alleles through a method of Polymerase Chain Reaction (PCR); more specifically re... | [
"thank you, I appreciate the article."
] |
[
"What's the science behind liking things? Why does one person like and identify with some things, while others choose differently?"
] | [
false
] | null | [
"\"Like\" can be divided into several underlying processes:",
"1) Interpersonal affection seems to be mediated by ",
"vasopressin",
" in males and ",
"oxytocin",
" in females.",
"2) The ",
"dopamine reward system",
" is responsible for many positive feedback sensations from drugs, food, certain beha... | [
"I can't answer the question, but I know Paul Bloom (Yale) studied your question. He talks about it ",
"here",
". Maybe that helps to answer your question a bit! "
] | [
"The truth to your question is, we have not yet reached a truly defined answer to this question. The question itself delves deep into many different fields and aspects of Psychology and brain science. However, the current modeling leads to the following hypothesis. Because we live our lives running backwards in tim... |
[
"Can an aircraft wing or propeller cavitate like a boat propeller?"
] | [
false
] | null | [
"Cavitation happens when changes in pressure around the propeller are significant enough to cause some of the water to turn into vapor. The bubbles of gas collapse rapidly and cause damage. ",
"Air is already a gas, so it can't cavitate."
] | [
"What if it were going fast enough to heat the air into a plasma? Like the Space Shuttle coming back from space, for example."
] | [
"Agreed that it won't happen. However there are planes with supersonic props. ",
"Tupelov Tu-95 Bear",
"."
] |
[
"Does the frequency of switching a transistor on and off affect its performance/longevity?"
] | [
false
] | I know RAM wears out, and this is probably what limits the life of a computer, but does a similar thing happen to the core? Maybe the semiconductor loses its dopants? Just trying to lead the conversation, I could have no idea what I'm talking about. | [
"It doesn't \"lose it's dopants\", but high frequency operation does take it's toll on CMOS logic devices, in at least a few major ways. ",
"One major way is due to the fact that a static (non-switching) CMOS circuit has very low current flow in it, and therefore very low heat generation. Heat accelerates alm... | [
"Transistors are rated for for different frequencies of operation, determined by how they are manufactured. IIRC the amount of doping is one factor while the semiconductor used is another. For example, silicon doesn't work well at really high freqencies (ie. gigahertz range). The fast on/off switching will caus... | [
"I couldn't tell you, but you might want to try asking ",
"/r/electronics",
" as well, it's right up their alley."
] |
[
"How come vaccines don’t pass from mother to child?"
] | [
false
] | If they share the same blood before birth, which I’m 90% sure they do, wouldn’t their immune system keep information from when the mother got vaccinated? | [
"The mother and the fetus do not share the same blood. The function of the placenta is to facilitate the exchange of nutrients, gases, and wastes while keeping the blood supplies separate. There are a type of antibodies called IgG that can cross the placenta. They give some protection to the developing fetus in ute... | [
"They pass stuff, but not all.",
"Vaccines trigger immune response to form a sort of imitation cell that they can automatically produce antibodies against. Think of it as a dossier of weapon against different enemies. When vaccinated, your body learns about the capsid or binders of the virus (that is why vaccines... | [
"That is correct the baby and the mother doesn't share their blood. It's the reason why a mother infected by the HIV (which is transmitted by exchange of fluides) doesn't infect her baby until she deliver. And by doing a cesarian you can greatly reduce the risk thus the baby isn't infected by HIV while the mother w... |
[
"Can someone explain how Impedence Matching works?"
] | [
false
] | A is specialized cable which enables the transfer of Alternating Current with a frequency high enough that the length of the cable begins to matter. (Basically anything higher than mains power). At the end of the line there is usually an impedence-matched load resistor. What is that and how does it work? Does it simply absorb the wave pulse so that a return line is not needed? | [
"This is a great response. It should also be noted that when the two mediums are impedance matched, it also minimizes any reflections at the boundary. This helps to minimize signal distortions, so it helps in keeping the signal/noise ratio high. This makes it easier for a receiver at the end of the transmission l... | [
"This is a great response. It should also be noted that when the two mediums are impedance matched, it also minimizes any reflections at the boundary. This helps to minimize signal distortions, so it helps in keeping the signal/noise ratio high. This makes it easier for a receiver at the end of the transmission l... | [
"You should ",
" watch this ",
"video",
" from Bell labs, where the host use a wave machine to visually show how waves work. You can actually get an intuitive feel for what the impedence matching does, it's very interesting!"
] |
[
"Could neutrinos escape a black hole?"
] | [
false
] | So, let's assume, in line with the most recent (although still not accepted) observations, that there is a way of causing neutrinos to travel faster than light. My mate is in a spacecraft, orbiting a black hole. For convenience's sake, let's say he has a period of 10 seconds. He ejects me from the spacecraft in such a way that I'm stationary relative to the black hole. Also I'm carrying a superliminal neutrino emitter, which is sending out a continuous S-O-S pulse pattern. As I fall toward the black hole, and eventually past the event horizon, what does my mate in the spacecraft see with his amazing hand-held neutrino detector? | [
"We don't know. Our theories about black holes are based on relativity, which requires that nothing can travel faster than c. If neutrinos can, then relativity is false, and we don't know enough about how black holes work to say."
] | [
"Because the escape velocity has nothing to do with black holes. You can't simply apply Newtonian physics here. It is actually only a coincidence that naively computing the escape velocity for a black hole yields the speed of light.",
"An easy way to see this is considering this: You don't actually need to travel... | [
"No. ",
"This comment by RobotRollCall is a beautiful explanation of why not.",
" - Gravity works by bending spacetime. Black holes are special because they effectively bend it all the way around to wrap up on itself. Once you are inside the event horizon, all trajectories through space bend back around to poin... |
[
"Hydrogen peroxide (3%) in ears?"
] | [
false
] | null | [
"I wouldn't do this on a regular basis. Hydrogen peroxide (a weaker solution than above) is sometimes used to soften built up ear wax in order to remove it with a syringe. This should only be done if you have impacted ear wax that is causing problems.",
"Using peroxide routinely would likely remove, change, softe... | [
"Thank you for the precious information!",
"\nDo you also happen to know whether hydrogen peroxide diminishes the immune system due to the body's over-reliance of it as being an anti-infectant?"
] | [
"It shouldn't diminish your immune system as you shouldn't be using it unless you have small wound (i.e. paper-cut, scrape etc). You should only be using it at a 3% solution (or less) for this purpose. You shouldn't be exposing your mucous membranes or really bad wounds to hydrogen peroxide.",
"Plus, hydrogen per... |
[
"Two Time Dimensions"
] | [
false
] | What if there were two time dimensions? Would we represent it as a coordinate plane like we do for spacial dimensions? if so what would a point on this coordinate plane represent? (Also if we're thinking of it as a coordinate plane, what if we added the z axis, and thus a third time dimension?) | [
"It would be even more wibbly...",
"Though seriously, physicist Itzhac Bars has some ",
"interesting thoughts on two-time physics."
] | [
"I'm not an expert in multiple time dimensions, but I like ",
"this overview on wiki",
"."
] | [
"I've been working on this as a side project myself recently. Starting on the assumption that the Minkowski metric (for 2 time, 1 space) can be written as (-,-,+) and that Lorentz scalars must remain invariant under boosts, you can derive the form of the Lorentz transformation. For this metric, all you get is that ... |
[
"Are mitochondria significantly different in different species?"
] | [
false
] | If it were possible to replace the mitochondria in, say, a giraffe cell with mitochondria from a hyena cell, would it work? | [
"The current prevailing theory is that all mitochondria are descended from a bacterium that was swallowed by another prokaryote before the Eukaryotic cell even existed--so before animals, plants, fungi, algae, other protists, etc. split off from eachother. Because of that, it's believed that no living eukaryote dev... | [
"If you didn't research this, why are you answering?? "
] | [
"Not an expert, just got interested in the subject, please feel free to add:",
"http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0060213#s6",
" ",
"Additions: [[My thoughts on the subject, keep in mind my amateurism]]",
"The wealth of recent data from MA experiments across taxa provides ... |
[
"If I put a refrigerator in a room with the lid open, does the room get warmer, cooler, or stay the same?"
] | [
false
] | null | [
"It depends if the fridge is plugged in and what sort of circumstances you want to contrive for the room. But generally speaking, the room gets warmer. ",
"If the refrigerator is plugged in and running it's still actively trying to keep its insides cold, so it is going to be using electricity which ultimately end... | [
"“it depends on if the fridge is plugged in”",
"Ok."
] | [
"Is your refrigerator running? This entire thread is literally just a set up for that joke so let's get it out of the way now."
] |
[
"Why are position and momentum related by Fourier Transform?"
] | [
false
] | For the context, here is a brief description of my understanding level - I want to understand why the Heisenberg Uncertainity Principle is true and although, I feel like I am being thick headed or something, I really cannot figure out how we went from momentum is inversely proportional to wavelength to the Uncertainity principle. The most common answer is that it results in position and momentum being linked by Fourier transform, but I fail to make the jump. Does it come from Schrodinger equation or is it more fundamental than that? I would be really thankful if you can add some comments. | [
"The uncertainty principle is true for ",
" wave. It says that a wave can't be both constrained in space and in wavelength at the same time - the more constrained it is in space, the more spread out it is in wavelength. (I'm going to use wavelength and frequency interchangeably, because for a constant speed of li... | [
"I actually don't like the fourier transform explanation for someone who knows math. It's a much more general rule than that, and honestly, ",
"wikipedia does a pretty good job of explaining the linear algebra derivation of it."
] | [
"No, any pair of non-commuting observables obeys a minimum uncertainty relation, even if they’re not related by Fourier transform."
] |
[
"How many times has the water we drink today, been consumed by past generations?"
] | [
false
] | null | [
"Counting the number of times water is consumed would be incredibly difficult and has a few fundamental challenges:",
"1) Water molecules are created (hydrogen and oxygen atoms joining together as H20) and destroyed (braking water apart and the atoms forming other relationships) constantly. This is happening in y... | [
"What? Why has it been consumed? "
] | [
"But water is H2O and hydrogen can be removed from the oxygen atom to form OH- so it needn't be the same water molecule forever",
"Edit: or a hydrogen can be added to form hydronium"
] |
[
"What enables aquatic mammals to hold their breath so much longer than land mammals?"
] | [
false
] | Relative to body size, it doesn't seem like the lungs of aquatic mammals are any larger than those of land mammals; yet a sperm whale can hold its breath for an hour and a half and most humans can't hold their breath for more than a few minutes. Is there something special about their lungs? Is it due to metabolic differences? Are humans just especially bad at it? | [
"Excellent question!",
"Different Marine Mammals use different strategies for these problems. Here are the big evolutionary advantages developed within marine mammals, though different marine mammals use different ratios of each depending on their environmental constraints.",
"1.) Myoglobin: Basically, this act... | [
"Whales exhale when they dive. Their enormous blood supply can hold an immense amount of oxygen. Aquatic mammals have a diving reflex (which can be partially activated in humans in experienced free-divers) which lowers blood flow to non-essential muscles and organs, reducing oxygen consumption."
] | [
"All marine mammals have haemoglobin, but other organisms in the marine environment may use haemocyanin (a copper based oxygen binder found in crustacea and molluscs) or haemorhythrin (iron based, found in polychaetes) to carry oxygen.",
"edit: some fish don't even have any oxygen carriers at all, and carry oxyge... |
[
"Why does Google's Deep Dream code add shoggoth eyes, creepy tendrils, and warped animal faces to everything?"
] | [
false
] | , , and . Seriously, I think I understand what it's designed to do, but why does it warp things into an oddly specific sort of nightmarish? | [
"It has to do with the training data and what sort of high-contrast, \"easy to find\" features it contains. Most photos interesting to Google have \"human interest\" aspects like people and animals, so that's what they train their ANN with. Eyes are a good example of a feature it's easy for the network to figure ou... | [
"So, I'm going to type this up under the assumption that Google is using a convolutional neural network, which I'm pretty sure is true.",
"So, having said that, I should start with what that is. CNN is basically an algorithm for training object detection models in image processing (most commonly, anyway). It kill... | [
"From what ive read, the way they generate the images is to run the CNN in reverse: they give it an image and ask it to generate (as opposed to locate) the 'eyes' or the 'dogs' or whatever the network was trained to detect"
] |
[
"What is the “colorful static” that some people see?"
] | [
false
] | So a couple years ago, I found out that not everyone can see this, but what it looks like to me is what I like to call “colorful static”. Basically it looks like your vision isn’t completely clear because of all these tiny dots flashing in front of your vision, but at the same time you can see everything just fine. I can see them better at night, and they’re separate from the eye floaters people get. What I’m trying to find out is what it is, and how it’s caused. | [
"Are you talking about ",
"visual snow",
"? We actually don't know the cause at the moment."
] | [
"Like ",
"/u/albasri",
" said, we don't know the cause of it. So what I'm going to write here is purely speculative. Take it with a grain of salt.",
"Visual snow seems to be highly comorbid with high-pitched tinnitus (",
"68% in this case report",
"). There is reason to believe that the two sensory proces... | [
"Oh yeah I am! I didn’t realize it had a name"
] |
[
"slow light"
] | [
false
] | Does anyone know of any good books that do a thorough job of covering the material? Or a good review article? If anyone actually works on this, I would love to pick your brain. Edit: since I wasn't clear (sorry, I was on my phone), I'm looking into more on kind of effect. Specifically, I'm looking for a book that might cover the material well, or a good current review article. I'm posting here in the hope that someone works on something similar, or has encountered it in their studies. | [
"also, it doesn't ALWAYS travel at the same speed through a medium, it depends on frequency, intensity, and shape of the pulse. the intensity dependent changes are nonlinear effects of the medium that only start popping up for really intense pulses."
] | [
"classical and quantum mechanical on-resonance nonlinear optical effects. its particularly well pronounced in BEC's because of the whole \"single quantum state\" thing, but it can happen in any medium where you can control the absorption."
] | [
"something a bit more specific. mechanisms (EIT, SIT), theory, papers (eg. Hau's paper in nature circa 1999), information on stopped light, etc.",
"I know the general story, I want specifics."
] |
[
"Do magnets lose their magnetic properties over time? And why does dust seem to strongly affect how magnetic a surface is?"
] | [
false
] | [deleted] | [
"Do magnets lose their magnetic properties over time?",
"Over very long times (billions of years), when heated too much, with mechanical shock, or when put in strong external fields, yes.",
"I don't understand the second question."
] | [
"Materials maintain magnetization for billion of years if they are not heat over the curie's temperature. That's the way how geologists recognize the movement of plates over million of years. "
] | [
"Materials maintain magnetization for billion of years if they are not heat over the curie's temperature. That's the way how geologists recognize the movement of plates over million of years. "
] |
[
"How is our brain able to pinpoint specific voices in crowds and then focus in on what they're saying?"
] | [
false
] | null | [
"Because our hearing system is absolutely amazing. And I mean utterly, utterly incredible.",
"Sounds are made up of harmonics. These are, basically, a bunch of different frequencies that are mathematically related to each other, and the relative volumes of them all determine the ",
" or ",
" of the sound.",
... | [
"This problem, in acoustical psychophysics, is referred to as the cocktail party effect. It has been studied, quite a bit. Almost 100 years ago, scientists made recordings of 6 people reading books at the same time. A listener can attend to only one of the six. If you playback the recording, a listener cannot parse... | [
"The cochlea is part of the inner ear, and is a snail-shaped (i.e. curled up) organ that starts out wide at the base and gets narrower and narrower towards the apex. The cochlea is topographically tuned to different frequencies, which means that higher frequency sounds are recorded at the wide base, while lower fre... |
[
"Why aren't we moving at the speed of light?"
] | [
false
] | Velocities are relative - spaceship A zipping away from spaceship B at a million MPH is the same as saying spaceship B is zipping away from A at a million MPH. But what is one spaceship is a photon? The photon zips away at c - does that mean the spaceship zips away from the photo at c? The explanations elsewhere I've found boil down to "something with mass can't go c, so no", which is dissatisfying. Why aren't we all moving at the speed of light relative to photons? (Obviously we aren't because we experience time) | [
"How long an explanation do you want? The first thing to note is that massless particles do not have a rest frame. By definition massless particles move at c in any inertial frame, so there is a clear contradiction if you try to construct one with a massless particle at rest.",
"There is also a geometric explanat... | [
"The laws of physics are invariant under translation, rotation, and Lorentz transformation. Lorentz transformation lets you turn any slower-than-light velocity into any other slower-than-light velocity, but c is still c. There is no reference frame where the photon is not moving."
] | [
"I think everyone has missed your real question, so I'll restate how I'm interpreting it. Ignore the photon, it is a red herring here and doesn't really get at the real question imo.",
"Say we have a spaceship and a planet. I'm on the planet and a monkey is in the spaceship. The spaceship is travelling away from ... |
[
"I've heard that the Azolla fern could be used for carbon sequestration. How do you measure how much CO2 a plant is absorbing? Could an individual person measure how much CO2 a plant take in?"
] | [
false
] | null | [
"Just to be clear, you cannot just weigh the plant. It is mostly water. You have to dry it first.",
"Plants also do reactions other than photosynthesis, so the element ratio in the plant will not be the same as in the photosynthesis equation. Lignin has a higher carbon content than carbohydrates, so if you assume... | [
"Would it not simply be dependent on how fast the plant grows, which can be measured by weighing the plant with all other inputs (eg. water) controlled? The chemical equation for photosynthesis would enable calculation of the amount of carbon dioxide reactant. Wikipedia states that azolla fern can double its biomas... | [
"Here is an outline of an experimental design you could do at home to measure the carbon content of a plant: ",
"https://edu.rsc.org/feature/the-carbon-dioxide-problem/2020244.article",
". It's behind a signup wall but you get one free article.",
"Instead of waiting for the leaves to decompose, after sealing ... |
[
"How does inhaling marijuana smoke affect your mucosa?"
] | [
false
] | Specifically, how does the smoke from marijuana (asking here about both unfiltered and water-filtered smoke) affect your mucosa? Specifically, the gastric, oral, buccal, and bronchial mucosa are of interest. Specific questions regarding the mechanism of action of smoke on mucosal surfaces I have include: is cottonmouth a mental or physical phenomenon? Can irritation of the mucosa cause swelling, vasodilation, or water retention in the affected areas? Otherwise, I'd like to know generally what happens physiologically. Citations of studies instead of comments are just as appreciated! Reg | [
"There is only a little good info on this, but we ",
"can start here.",
"\nFor a study of this nature, I'm happy with what they published, and this is even a reasonable sample size. They also have good p values and stat's tests, excepting the results for Cocaine-Marijuana smokers.",
"Table 5 shows the rates ... | [
"The DCO in Table 4 is also, albeit only slightly, below predicted, and is indicative of a restrictive lung disorder. Keep in mind however that wheeze, sputum production and acute bronchitic episodes in MS are elevated, which are obstructive disorders.",
"I personally feel it's reasonable to predict MS will see ... | [
"Obstruction is more acute than restriction.",
"Obstructive lung diseases include asthma and COPD, and refer to the obstruction of airflow entering/exiting the lungs. They're generally related to inflammation and airway constriction due to irritation. Chronically they become worse due to the loss of lung compli... |
[
"Is it possible that one of the gene edited Chinese twins is does not have their genes edited to fight HIV as part of a placebo study?"
] | [
false
] | null | [
"Who knows. That's not what they said they did. "
] | [
"Well no shit that’s not what they said. The premise of my question wasn’t what they said it was the possibility of a placebo study. Granted a speculative question but your response neither adds to nor detracts from the discussion. It merely points out the most obvious by stating that they didn’t say that. As thoug... | [
"The question in your post is about what they did. What are you trying to ask? Is it possible to do a study where the genes of one fertilized egg are edited and the genes of another are not and then both are implanted? Sure, why not. "
] |
[
"Is there a function/equation for every different combination of graph?"
] | [
false
] | So as the title says, If I were to have a graph let's say showing sales over time for a specific time frame, would it be possible to actually form an equation for that specific graph? I'm not sure how feasible it would be but theoretically is there an equation for every single graph you can draw? So if I were to right now draw a random graph, could it be possible to find an equation for that graph no matter how many zig-zags there are in it etc? | [
"You have to realize that the functions that you learn about and use in school are very limited. You learn about polynomials, rational functions, trigonometric functions, exponential functions, logarithmic functions and that's basically it. Theses are the ",
"Elementary Functions",
" In the grand scheme of \"Al... | [
"A function is a set of x-y coordinate pairs such that there is at most one y-value that gets paired with a given x-value. I assume that's what you meant by graph. So really the question is if there's an equation for every function.",
"But if you're asking about just ones that can be written out, the answer is no... | [
"If I were to have a graph let's say showing sales over time for a specific time frame,",
"This is a special case, because you probably only measure \"sales\" at discrete intervals. Like every quarter or every month. ",
"Given a graph like this, with y values at discrete x intervals, you can always write an equ... |
[
"Are there contradicting phylogenic trees both based on genetics such as cytochrome c and something else? Or are they all very harmonious?"
] | [
false
] | null | [
"You can certainly have contradicting trees if you use different characters, genes vs morphological characters. You can even have contradicting trees if you use different tree searching methods (distance-based methods, or character-based methods), and choose unwisely, given the limitations of some methods in differ... | [
"In phylogenetics, we are usually concerned with estimating the \"Species tree,\" which reconstructs the order and timing of speciation events. For instance, we try to figure out which of the great apes shares the most recent common ancestor with humans. We can reconstruct this phylogeny using any type of inherited... | [
"I don't mean to seem like I'm trying to nitpick your posts, but I have some points of clarification on this as well:",
"Weights are not assigned in Bayesian and maximum likelihood analyses in the way that they can be in parsimony analyses. What are probably most analogous (but still considerably different) to pa... |
[
"Theoretically speaking, could antimatter be contained and stored?"
] | [
false
] | My understanding of antimatter is limited, but what I do know is that if antimatter meets regular matter then they destroy each other. With that in mind, is it possible in theory for antimatter to be stored? For example, a chunk of antimatter suspended in a vacuum by a magnetic field. I imagine it would take a lot of power and technology we're nowhere close to now, but is it possible? I've seen antimatter used as weapons in a few sci-fi stories so it got me curious about how it would be stored/manufactured. | [
"This is already done, in electromagnetic traps. It's really difficult, and the length it can be trapped for is limited."
] | [
"There's always a probability that the antiatom will be found somewhere sufficiently far from the trap centre and annihilate with a regular atom."
] | [
"Why is the time span limited? Is this something to do with the magnetic field or stability of the antimatter, etc?"
] |
[
"If an issue of aging is rising levels of cortisol, why not remove the Zona Fesiculata or else remove an adrenal gland when you have higher levels of Cortisol?"
] | [
false
] | From what I understand, Cortisol is only really useful during gestation and in small doses, stimulating the conversion of T4 to T3. As you get older, Cortisol is catabolic on everything, making you store fat viscerally around organs instead of subcutaneously (terrible for life span). At high levels, Cortisol will shut down TRH and TSH, inhibiting T$/T3, which lowers metabolism. Cortisol also lowers the reproductive axis, negatively effecting levels of GnRH, LH, and T. High levels of Cortisol also causes higher sodium reuptake, since it overwhelming the 11BHSD at the kidney that makes cortisol unable to bind to the Aldosterone receptor (since both cort and aldo can bind to the receptor). So, at high levels of cort, you get higher sodium reuptake, causing high blood pressure --> thus the need for low sodium diets hen you are older. Also, since CORT is a glucocorticoid, it ups the glucose in the blood, so even more high BP. Cortisol, since it is catabolic, also causes you to lose calcium from the bone (since it degrates the collagen, so there is no where for Calcium to be put on). Yes, while messing with the endocrine system can be dangerous, why isn't removing an adrenal gland (or at least the cortex) an option FOR WHEN YOU ARE OLDER? (unless it is, and I didn't know?) The adrenal cortex makes weak androgens, cortisol, and aldosterone, the only one of which is necessary for life is aldosterone. Seeing as you have higher levels of cortisol anyway, won't it be enough if you just have one adrenal gland working? This is just me thinking, and wondering what you all have to say about it! :) added older part. | [
"A number of thoughts come to mind about your assertion. I think you can claim a superficial level of plausibility, in as much that, nothing you say is actually wrong. However, I think the difficulty lies in the fact the system is so complex, that it is possible to find supporting observations for almost any hypoth... | [
"first, i think you should really understand what cortisol does[wiki it, i know this is ask science but theres A LOT of information regarding cortisol; it interacts with so many aspects of metabolism and the body that its next to impossible to explain it briefly here. I've looked over the wiki article and its spot ... | [
"Thanks! That was the kind of answer I was looking for :) "
] |
[
"How do we know what the Milky Way looks like?"
] | [
false
] | You always see pictures of the Milky Way, but I assume this is just interpretations. How do we know its a spiral galaxy, and where we are in relation to the rest of it. | [
"From one of my previous answers to this question:",
"Star counts. Lots and lots of star counts. Mapping the galaxy is a very difficult, pain-staking, and error-prone process. The basic idea is that astronomers count the number of stars brighter than some value in various directions. As you decrease the lowest br... | [
"The dust is a problem for optical light, but if you work in the near or mid-infrared, its extinction is much reduced and you can actually see stars through the dust. Of course, you still have to deal with the fact that any stars on the other side of the galaxy are at least ~30,000 lightyears away.",
"Also, the r... | [
"Sky surveys and then models based on this. The Sloan Digital Sky Survey is one of the more modern spectroscopic surveys. This data can then be fed into models. (SDSS: ",
"http://www.sdss.org/news/",
")",
"There are areas of course that cannot be mapped, because they are 'out of view'. For example you cant l... |
[
"Books on the theory of evolution?"
] | [
false
] | null | [
"If you want to read everything, start at the beginning, which is slightly ironic since the topic is evolution, and thinking has, well, evolved:",
"On the Origin of Species by Means of Natural Selection",
"Warning PDF."
] | [
"Thank you. And where do I go from there? I would also like to read the history of it all. The response it got and the arguments against it."
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"A good home for this question is our sister subreddit ",
"/r/AskScienceDiscussion",
". It might be too open-ended or speculative for ",
"/r/askscience",
". ",
"/r/AskScienceDiscussion",
" is... |
[
"As a kid my mom told me not to freeze my plastic water bottles because the frozen water would attatch to particles on the plastic. Is this even remotely true?"
] | [
false
] | I had a lot of warm water as a child.. | [
"There is a slight truth to it, in the sense that ice crystals need something to nucleate around, so if your plastic is a bit rough (on a microscopic scale) that will be where ice crystals will start to form during the freezing process. ",
"As others have pointed out, that won't actually cause the particles to ge... | [
"The water isn't going to attach to anything, but plastics can decompose and get into the water and you end up drinking it... (after high temperature treatment, at least) and they can mimic certain hormones like estrogen which is one of the reasons for the shift away from using BPA-based plastics."
] | [
"not really. and even if it did \"attach,\" that does not mean that the plastic molecules would detach and float around in the water. And then, even if they did, there is nothing that indicates they would do anything more than just pass harmlessly through the body"
] |
[
"What makes a battery or cell \"heavy duty\"? How does it differ from a \"normal\" cell?"
] | [
false
] | null | [
"Marketing, usually. Industrial batteries are designed to have a longer shelf life by sacrificing capacity. Battery manufacturers sometimes come up with ways of improving the capacity of consumer batteries, and market the \"new\" design as something like \"MAX!\" or \"Heavy Duty\", but the terms have no official ... | [
"It doesn't really mean anything. It's usually just down to marketing."
] | [
"Does that mean these \"heavy duty\" cells have a higher capacity in exchange for a poorer shelf life, in comparison to say, \"standard\" cells like the average alkaline?"
] |
[
"Calculating the time dilation for an object inside a black hole returns imaginary values, does this have a deeper meaning?"
] | [
false
] | [deleted] | [
"The Schwarzschild coordinate chart does not cover the region beyond the event horizon. To the faraway observer, the inside region doesn't even exist. It doesn't make any sense to talk about the time dilation factor between a faraway observer and an observer beyond the horizon. "
] | [
"A Schwarzschild black hole singularity is always hidden behind a horizon. Naked singularities don't seem to exist but if they did, then, sure there could possibly be a single chart that covered all of the relevant spacetime. The Kerr metric for a superextremal black hole is one such example. ",
"The original que... | [
"Hmm, what if cosmic censorship were wrong and we had a naked singularity? An object could be closer to the center of mass than the Schwarzschild radius and we would still be able to observe it."
] |
[
"[Physics]My 12 year old wants to know if a microwave oven would turn thermal paper black? And, of course, regardless of what the answer is, why?"
] | [
false
] | null | [
"Your 12 yr old may also be interested to know that rubbing alcohol will also turn thermal paper black. ",
"I'm actually not sure why this is but if anyone out there has an explanation, I'd love to see it. My guess is that the alcohol causes the activation temp of the paper to change, but again I actually have no... | [
"It's not only water molecules but also anything opaque to that frequency of light"
] | [
"No, it is not the resonant frequency of water, that has absolutely nothing to do with it. It will heat a wide variety of dielectrics and conductors, not just water. Stop spreading this false rumour. ",
"2.4 GHz was chosen because:",
"It's fairly cheap and easy to generate high power waves with a magnetron, 2.4... |
[
"How can Olympic skiers jump the distance of a football field going 40+ mph without sustaining an injury?"
] | [
false
] | null | [
"Because the distance doesn't really matter (for the injury part). Imagine if they were on a horizontal plane. The height of the jump would not be that high relative to that plane.",
"Also, the angle of the landing zone to the angle of the skier when they touch down is small because the slope of the landing zone ... | [
"Yup, adding to that last point, imagine throwing an egg or water balloon up in the air. If you try to catch it by just putting your hand out they will break. But if you continue with the egg/ water balloon's motion and slow it down more gradually then you reduce the amount of force that is experienced and decrease... | [
"Because of the sloped landing. Also the terminal velocity of a flying skier is relatively low because their wide skis acturally generate lift. That's why it's crucially important for a ski jumper to maintain the correct pose and angle in flight - if one of the skis stalls the jumper will tumble down and slam into ... |
[
"Why are there common food allergens?"
] | [
false
] | [deleted] | [
"A theory of why people seem to be developing so many more food allergies is not just because or food sources are more globalized than ever, but due to the inflammation response. Your microbiome (all the bacteria living in your body) have a big effect on your immune system and how it responds to external factors. B... | [
"Several reasons have been given as to why peanuts are more allergenic than other foods. Seed storage proteins are extremely ",
" from heat, acidity, and proteolytic activities (Koppelman et al., 2010). Moreover, factors associated in the manner in which peanuts are processed can also lead to higher allergenicity... | [
"You drink a big ol' glass of Kiefer Sutherland, he will help support a healthy immune system...",
"Yes that was a typo, I meant Kefir. Thanks :p"
] |
[
"Is there any difference between a black hole made out of regular matter and a black hole made out of antimatter?"
] | [
false
] | Suppose we have two identical stars (size, mass) except that one is made of matter and the other of antimatter and they both implode into black holes? Are the two black holes identical? If not, what happens if they collide? | [
"No there is not. Black holes only have three properties: mass, spin, and charge."
] | [
"Specifically, the \"no hair\" theorem— which says that black holes only have those three properties— implies that black holes don't conserve baryon number (or ",
"lepton number",
"). A black hole made from the collapse of a matter star would be indistinguishable from one made from the collapse of an antimatter... | [
"At Cern, a physicist I was talking to was in the middle of an investigation to determine whether anti-matter followed normally gravitational effects, because an element of string theory(pretty sure its super symetry but I could be wrong) says that anti-matter particles should 'fall up'. He also said the results wo... |
[
"Can water, if pressured enough, cut you?"
] | [
false
] | I have seen it happen sometimes in cartoons. The water would come out of a slit of a pipe and it would be so powerful that it would give the person a cut (it looked a lot like a paper cut). Is this possible? If it is how pressured would that water have to be? Also, I realize that my explanation is a bit messy, If you don't understand I will try to elaborate. EDIT: after what all the people have been saying, I'm beginning to look at my super soaker differently... | [
"Yes, there is an industrial cutting technique known as ",
"water jet cutting",
" which uses this method. Although, such methods usually mix in an abrasive compound to help with the cutting. I couldn't tell you the force required for the water to actually cut you, though."
] | [
"Thanks! It's weird how a liquid can have such effects. "
] | [
"Water, if pressured enough, can blow your limbs off."
] |
[
"My grandfather had schizophrenia. However, at my father's age it's safe to say that he does not suffer from the same disease. What are the odds of me having it?"
] | [
false
] | null | [
"We have strict guidelines against medical advice. If you have any health concerns, please see a physician."
] | [
"This is not medical advice though, im just trying to get some information on my odds"
] | [
"Please see the guidelines. Alternatively, you could as a more general question about the heritability of schizophrenia in general."
] |
[
"Eugenics from a purely scientific viewpoint."
] | [
false
] | I am interested in the cons and pros(if any) of eugenics from a purely scientific viewpoint, rather than historic, political, or moral perspective. It is my understanding that eugenics fails to be a scientifically valid model for creating the "supreme race" of humans, but I have yet to read any detailed explanation as to why. I am in no way a supporter of eugenics, but if we can breed a horse specifically for speed, or a dog to have a short nose, why can't we do the same with humans, or if we can, what BIOLOGICAL (not social/moral) effects will it have (either in the short term or the long term)? Again to make it clear, this is posted in askscience because I would like to avoid any moral/political discussion. | [
"Of course we could breed humans for whatever we would like, just like any other mammal. Humans however are slower at reproducing than cats, dogs or pigs, so it would take more time.",
"Biologically, well, we would probably see some of the same side effects we see in other artificially selected breeds of mammals:... | [
"Eugenics is dangerous from a biological prospective without accounting for morals and politics. Traits are linked together and selected for in complex networks that we're nowhere near understanding. By artificially selecting for one trait, we don't really know what we're pulling with it. ",
"The implications for... | [
"This has been covered a few times before, but I'll add a quick summary (leaving out the whole 'shallowing the gene pool' thing that others have covered pretty well). The biggest issues are:",
"1: Defining 'good' genes",
"The classic example for this problem is the mutation(s) that causes ",
"sickle celled an... |
[
"How would a Vantablack coating affect a laser cutters ability to cut?"
] | [
false
] | [deleted] | [
"When a surface is black it means it is absorbing all of the light heat. If it were the opposite, vantawhite, little/no heat would be absorbed and the the laser would only be reflected and rendered useless. So, I'd bet that vantablack would be cut more efficiently by a laser, as it would more readily absorb the hea... | [
"So, I'd bet that vantablack would be cut more efficiently by a laser...",
"I agree. Especially since vantablack is made of CNT, carbon being VERY combustible.",
"However, the question becomes would the underlying material be cut more efficiently as well?",
"I don't know for sure, but my gut says no. In fact ... | [
"Vanta black works on the same principal as an anechoic chamber, it may absorb the heat, as that is what it is designed to do but that heat wouldn't be centralized it would be dispersed along the material, difference similar to some one standing on your foot with a stiletto or a boot, same weight but one is more co... |
[
"Why does it appear that \"all of a sudden\" many people are allergic to gluten?"
] | [
false
] | Up until two or three years ago I had never even heard of Coeliac disease or Gluten free diets, or a Gluten/Wheat allergy. Now I know at least a dozen or so people that have lived their whole lives eating wheat products that no longer can. I also read on wikipedia that the prevalence is 1 in 105 in America, yet it is 1 in 1,750 worldwide. Why the sudden jump? Is it real? Or just a fad diagnosing spree? | [
"Celiac has been a thing for a long time, but you only heard of it in serious cases where continued consumption of wheat would end in death. That is very real.",
"In America we eat lots of wheat and we have advanced medicine to test for such things. Lots of places in the world don't have one or both of those so... | [
"Worth noting:",
"Up until 70-130 years ago, most breads were sourdoughs. Sourdough is a combination of at least one lactobacillus (lactic acid bacterium) and at least one yeast (usually not Saccharomyces cerevisiae, common bread yeast- and, in fact, sourdoughs that are intentionally inoculated with S. cerevisiae... | [
"As this article demonstrates",
", the diagnosis was originally only considered and tested for in patients with gastrointestinal complaints. The golden standard was endoscopy and biopsy. The screening blood test was developed and is quite sensitive and specific and so testing has become much less invasive and che... |
[
"What is the purpose of the white part of eyeballs?"
] | [
false
] | null | [
"They are thought to make it easier for humans to see what other humans are looking at, facilitating nonverbal communication."
] | [
"\"Human eyes are somewhat distinctive in the animal kingdom in that the sclera is very plainly visible whenever the eye is open. This is not just due to the white color of the human sclera, which many other species share, but also to the fact that the human iris is relatively small and comprises a significantly sm... | [
"Do you have a source for that?",
"It doesn't seem obvious to me that that is strictly the reason why we evolved the white portions of our eyeballs."
] |
[
"Dear AskScience, why do humans create pendular motion with their arms while walking?"
] | [
false
] | I've always assumed it was to create forward momentum and balance, but please enlighten me on the actual physics behind the behavior. Thanks! | [
"To maintain balance, or, more specifically, to keep your centre of gravity over your feet. The left leg goes forward and the right arm goes forward too, and vice versa. Try walking with your hands straight down by your sides and without rotating your hips. Now try running (preferably somewhere where you won't get ... | [
"You may find that you are swivelling your hips or shoulders or swinging your elbows to compensate for the lack of arm movement."
] | [
"As it says in the sidebar, personal anecdotes and layman speculation are unwelcome in this subreddit."
] |
[
"On the most fundamental level, what is a computer?"
] | [
false
] | Inspired by xkcd comic. What is a computer? When this guy , what exactly is happening? | [
"The word you're looking for might be \"",
"Turing Machine",
"\". It's a mathematical description of what a computer ",
" - on a purely abstract level, without concerning yourself over whether the computer is built out of transistors, rocks, redstone torches, or clockwork.",
"The original Turing machine des... | [
"At the absolutely most fundamental level, it's nothing more than lots and lots of switches. Millions and millions of them. The switches are called transistors. Hooking up a couple transistors in the right way give you logic functions with 1's and 0's, which are really just high or low voltages. With logic function... | [
"Computer scientist here: This post isn't getting enough love. Other people are describing what an electronic, digital computer is made of/how it works, but at a basic level a computer doesn't have to be electronic or digital.",
"If your question is, \"Fundamentally, what is a programmable computer?\" this is th... |
[
"What determines the smallest particle size for powders?"
] | [
false
] | Can anything be ground down 'to the molecule' ? | [
"Electrostatics, the amount of effort you're prepared to invest in production, the amount of effort you're prepared to invest in storage, and the amount of time you want your powder to last."
] | [
"Further question: Wouldn't something ground down to 'the molecule' effectively be a gas/liquid?"
] | [
"Not an expert, but as I recall it has to do with the current thermodynamic properties (temperature, pressure, etc) and phase boundaries of the material.",
"e.g. ice isn't a liquid/gas, even if you crush it up. "
] |
[
"A horse goes through puberty in its second year. Why is our physical development so slow?"
] | [
false
] | I can understand why our mental development would take a lot of time, since there is so much to learn - complex language and all the skills and knowledge we take for granted as adults. But human physical development is also remarkably slow compared to most species of comparable size. Why would this be? Wouldn't it be a rather sever disadvantage during our evolution? | [
"I'm away from home right now, or I could give you a more complete quote, but John Gottman in his book \"And Baby Makes Three\" talks about the evolutionary loss of our \"fourth\" trimester. Essentially, we are forced to be born too early because our greatest evolutionary asset (our brain) means that our heads woul... | [
"A lot points to the kinds of foods we ate in the ancestral environment. Hunter gatherers specialized in high caloric, highly nutritious food that took much learning to sucessfully gather.\nThis specialization probably happened slowly. There are monkies that break open nutritious nuts with tools. It takes years for... | [
"Yes but carrying the baby in the womb is also a constant energy drain."
] |
[
"Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Please only answer a posted question if you are an expert in the field. . In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for . If you would like to become a member of the AskScience panel, . Past AskAnythingWednesday posts . Ask away! | [
"How scientifically significant is the fact that water is most dense at 4",
" Celsius? In other words, the fact that there can be liquid water below the ice.",
"\nIt seems to me that this property of water played a huge role in developing life on Earth.",
"\nAre there any other materials that have such anomal... | [
"What are some of the present theories on the Great Attractor? What do we think is the cause of all the mass? How do we take anomalies like this into account when calculating for dark matter/energy? Are there other regions identified in other parts of the universe that also function as great attractors? "
] | [
"The great attractor is not an anomaly. It's a region of some dozen(s) of Abel clusters in relatively close confinement. In a big universe - a universe as big as ours - you get regions with many huge clusters packed close together and regions with no galaxies, cosmic voids. There are for sure other great attractors... |
[
"About all those lonely trees falling in forests..."
] | [
false
] | Everything is observed due to every particle being gravitationally attracted to every other particle which makes every particle in the universe 'visible' to every other particle? ...Which boils down to: there is always someone within earshot of a falling tree. Does this sound about right? | [
"This would hold if all these signals were uniquely distinguishable. But how could you tell, from gravity, the difference between a mass m at some distance r, and a mass 4*m at distance 2*r ? All you see are the sum of the effects, without any way to disentangle the whole set, even if you had measurement accurate e... | [
"It seems like I need to explain this more clearly... I was talking about being within 'earshot' as in observing a gravitational pull. If a tree falls or a particle moves it will create a wave which will ripple through space-time. So if a tree falls and no one is around to hear it the change in gravity although ext... | [
"This seems like it would belong more in ",
"/r/trees",
", no offense.",
"There ",
" always something in earshot of a falling tree, but sound is not gravity... Neither is light. Everything on our planet is linked through causality to some degree.",
"As for everything being causally linked in the universe,... |
[
"How does abnormal (too low or too high) blood sugar affect blood vessels?"
] | [
false
] | null | [
"This is an enormous topic. Sugar is an energy source, a growth signal, and can form adducts with cellular proteins. If you have a more specific interest in one of these broad areas, can you narrow your question so we can tackle it more effectively?",
" perhaps this is an accessible introduction: ",
"http://en.... | [
"That article you linked to, while short, actually answered it perfectly. Sorry, didn't realize it was such a generalized and broad question, but thanks. :)",
"Are you a doctor by the way? Just curious."
] | [
"Glad to hear it. I'm not a doctor yet, but I am a medical student."
] |
[
"Does music sound different on a space station?"
] | [
false
] | Does the lack of gravity affect the perceived quality of sound? | [
"As far as I can tell, no, it shouldn't. While there is, in fact, a term in the ",
"Navier-Stokes Equation",
" that represents the force on the air due to gravity, its effect on acoustic propagation is negligible. If there would be an effect, it would probably have to do with structural noise. One of the ways t... | [
"The ISS operates at sea level air pressure."
] | [
"I agree. The only possible reason I can think of that could cause music to sound different would be long-term physiological changes in response to micro-gravity, e.g., redistribution of body fluids."
] |
[
"How are video games “ported” to other consoles and PC?"
] | [
false
] | When a video game is “ported” from one system to another, say PC to Playstation, how difficult is this process? Is the entire game rewritten in the code that each system reads? Or does a PlayStation interpret the same kind of programs/code that a PC interprets? | [
"Let's assume the video game you're talking about is written targeting a specific system architecture, and a specific framework. For PC a common example would be Windows x64 and DirectX. Let's say we wanted to port the game to PlayStation. That would entail rewriting all parts of Windows and DirectX-specific code t... | [
"Programs including games are not written in a platform specific code, they are written in a more human-friendly language like C, C++, C#, Java etc. Those languages are quite abstract in the sense that they make very few assumptions about the hardware they are going to be executed on and you generally don't think a... | [
"Apart from actually porting platform dependent Code as mentioned by Fuet, one of the more time intensive tasks is complying with platform holders’ technical requirements. Things like QOL requirements, where and how a game saves its data, what to report to its servers, and even trivial things like the correct displ... |
[
"I have heard/read from a few sources that viral load is one of the factors influencing severity of the infection in Covid-19. How far is this true?"
] | [
false
] | For example, if person A gets a higher viral dose than person B, is his/her infection more likely to be more severe and has there been any research/studies conducted on this? Also, I'd like to know if there's a minimum viral dose that is needed for symptomatic infection, and if this dose varies from individual to individual. The new (mutated) strains of Covid-19 are said to be more infectious- does this imply that a smaller viral dose is required to cause symptomatic infection? | [
"In general, there is a positive correlation between initial inoculate and disease severity that has been shown for several viruses including this one. This at the population level, at the individual level it can be that 2 get infected by a similar inoculate but one does worse than the other etc."
] | [
"I have spent much time looking for any type of study or experiment finding a link between inoculum and severity of symptoms of Covid.",
"But of course, I could not find one, because purposely infecting subjects with various levels of SARS-CoV-2 to see levels of Covid symptoms in unethical. And there does not see... | [
"Yes, it is conclusive and perfectly normal. Though when one sneezes for example there is a multitude of viral particles, many are not even viable. Besides that, those that do get inhaled have to find suitable host cells, infect and replicate potentially forming thousands of new virions from a single infected cell.... |
[
"If combustion requires oxygen, what happens if I put a piece of paper in a vacuum and heat it really hot?"
] | [
false
] | I know it's possible for paper to burst in flame with high heat even if there's no flame, but I was wondering if the same would happen in a vacuum. Also, since in space there's no oxygen, what would happen if you send a rocket towards the sun? Sorry for my lack of science knowledge.. | [
"If paper is heated without the presence of oxygen, it undergoes thermal decomposition, also known as pyrolysis. This is similar to the process through which ",
"biochar",
" (and charcoal) is made. The carbohydrates and cellulose in the paper will break down into gaseous CO, CO2, CH4 and H2O, leaving a solid ca... | [
"What about radiation? Yes, you can't do conduction or convection in a vacuum, but radiation you can."
] | [
"It turns to carbon in a sheet."
] |
[
"Why do women typically have higher voices than men?"
] | [
false
] | Is there an evolutionary reason for women to have higher voices than men? I'm assuming it has something to do with sexual selection, although I may be way off base. Also, does this happen in other animals? EDIT: I'm not asking HOW women have higher voices, I'm asking WHY. Also, I thought about the size thing, but regardless of size, a large woman still has that "feminine" element to her voice, while a small man still sounds like a man. | [
"I think it's the other way around: why do men have lower voices than women? Female is the default, the Y chromosome only has 45 genes in it, compared to 20,000 or 30,000 in the entire human genome.",
"Women find deeper voices in men sexier",
", testosterone lengthens a man's vocal chords to produce a lower voi... | [
"I'm not professionally versed on this particular topic but I've done a fair amount of studying on it nonetheless. Compared to other primates, humans have been sexually selected to a much greater degree in favor of neoteny- the retention of childlike characteristics into adulthood. Comparing humans and other primat... | [
"Well shit, my voice definitely isn't sexy then."
] |
[
"Why can't we make spaceships go faster?"
] | [
false
] | What is preventing us from increasing the maximum speed of the modern spaceship? Edit: Thanks everybody for the answers, they were all amazing! | [
"With current technology the speed of modern spacecraft are limited by the amount and type of fuel we deem economical to carry into orbit with us. We have to carry the fuel with us as we don't have the technology ready to create fuel for us in space. Right now the most efficient fuel we have is Hydrogen and Oxyge... | [
"Delta-v",
" is one of the most important concepts in basic space flight. In a way it describes how big a change of velocity the spacecraft is capable of performing. This includes both accelerating and deccelerating as well as making course corrections or changing direction when done using engines. Excluding thin... | [
"I like both ",
"pozitron's",
" and ",
"Olog's",
" answers, but here's yet another way to put it:",
"Spaceships travel with rockets. Rockets work by conservation of momentum. If you want momentum ",
" you have to also create some momentum ",
" to balance it. You put all the ",
" momentum on some... |
[
"How can a real particle have negative energy?"
] | [
false
] | Hi, I'm reading Stephen Hawkin's "Brief history of time". There's a chapter where he talks about black holes and I assume is the precursor to hawking radiation, but basically it explains that at the event horizon there are particle-antiparticle pairs being created, some escape into space (particles as radiation, antiparticles annihilate pretty soon after their escape), but whenever a particle falls into the black hole it reduces it's mass (instead of increasing it). Hawkins says "Normally, the energy of the particle is still positive, but the gravitational field inside a black hole is so strong that even a real particle can have negative energy there". Cans someone elaborate on this? how is the possible? I mean to me it just sounds like "well, it has to be negative or else the black hole will grow, so lets just make it so" but doesn't really click (in my head) | [
"that explanation of hawking radiation (even if presented by hawking himself) is really just so laymen can feel they understand hawking radiation. it's not accurate. particles don't have negative energy. it's true that a positive energy particle would add to the mass, so your suggestion",
"I mean to me it... | [
"a particle has positive energy.",
"mind I'm only talking about this explanation , that doesn't mean hawking radiation cannot be derived rigorously"
] | [
"I just want to emphasize what he said: this explanation of Hawking radiation is an oversimplification intended to help a layperson understand sort of what Hawking radiation is, but it is an ",
" explanation. It's not totally wrong, but elements of it are wrong, and it's not the whole story. The idea of a real pa... |
[
"Why have we not been funding/seriously researching transplanting brains and directly hooking in motor functions to artificial bodies?"
] | [
false
] | null | [
"I posted this, as a response, to ",
"/r/askreddit",
" and it did decently well, so I am finally deciding to post here and see if anyone can help or at least help me understand why."
] | [
"Our question would be better suited to ",
"/r/AskScienceDiscussion",
". Please, consider resubmitting there."
] | [
"Resubmitting now."
] |
[
"How do parrots talk like us if they have a beak and no lips to form sounds the way we do?"
] | [
false
] | Okay, maybe this is a stupid question but yesterday I was chatting with my sister and she brought up one of her patient's parrot and how he greets everyone, sings lyrical and even says goodnight. She actually told me she was scared at first because the first time she entered his house, she greeted the patient (Hello [name]) and she heard this robotic like voice saying "Oh [patient's name] who is this?" And then the question came up. How do they talk almost like us if they have a totally different mouth? We change sounds based on our tongue and lips, but they have a beak, yet they can still sound human! Thanks to anyone who might respond. :) | [
"Birds have an extra throat structure called a syrinx that’s a bit more advanced than the larynx in mammals. Humans have to add mouth shape to what the larynx can do to get our sounds, but birds do it all with their syrinx!",
"(Birds still have a larynx, but it doesn’t vocalize.)",
"The syrinx can even be separ... | [
"They do indeed! It’s a credit to both bird and human brains that birds parse and attempt noises they can’t quite make, and human brains fill in the gaps where needed."
] | [
"I imagine that some of the sounds we make will give parrots issues too. P sounds, for instance."
] |
[
"Because temperature affects the speed of sound, how slow could the cold bring down the speed of sound?"
] | [
false
] | I assume it's not possible for sound to not move at all. I'm not exactly sure how this works other than temperature affecting energy levels. | [
"Well the limiting case is if you get it so cold that it becomes liquid, and then sound becomes much faster. If you treat nitrogen as an ideal gas down to the transition temperature, the lowest speed will be about 180 m/s, just over half as fast as at normal temperatures. "
] | [
"I suppose a vacuum would reduce it to zero. however a quick googling indicates that decreasing pressure doesn't affect it much. I'm left to assume that as pressure approaches 0, something changes; can anyone explain?",
"got my info from ",
"https://en.wikipedia.org/wiki/Speed_of_sound#Dependence_on_the_propert... | [
"Thank you for the response. "
] |
[
"Why does the power rule \"shortcut\" for differentiation work?"
] | [
false
] | I know what the power rule is and that it works. I've read the , but the mathematical notation is a little confusing. I guess I'm asking for a logical, intuitive reason why I can just turn the old exponent into the coefficient and reduce the new exponent by one. Thanks! | [
"One reason is that you can look at the ",
"Binomial Expansion",
" of (a+h)",
" in order to find (a+h)",
"-a",
" in the numerator of the derivative. What you'll get is something like (a+h)",
" = a",
"+na",
"h+ (Terms with a higher degree in h). Subtracting out the a",
" will give na",
"h+h",
"... | [
"Using the product rule to show why the power rule works is probably not very informative. Someone asking this question would likely have the exact same question about why the product rule works."
] | [
"By the product rule d/dx x",
" = d/dx (x * x",
")= x*(d/dx x",
") + x",
" * d/dx x = x * (d/dx x",
") + x",
"Using the same process again for d/dx x",
" gives:",
"d/dx x",
" = x * (d/dx x",
") + x",
" = x",
" * d/dx (x",
") + 2x",
"Once more gives us ",
"d/dx x",
" = x",
" * d/dx... |
[
"5 year-old asked what life is. Help?"
] | [
false
] | After waiting up most of the night for relatives to fly in on the red-eye, and being awoken at 6am by our darling child, he starts looking a little down. Us parents as him what's wrong, and he turns to us, and in the most manner-of-fact manner possible, says: While I appreciate that the question is vague, I trust over the more religious/philosophical subreddits, and would frankly prefer to be able to give him a factual answer. I'm only one coffee into the day, and can't even begin to shape the beginnings of an answer. Any suggestions on what I can tell him? | [
"An operational definition is MRS GREN: Life is something with \n Movement\n Respiration\n Sensitivity\n Growth\n Reproduction\n Excretion\n Nutrition"
] | [
"Well, at the very least it won't be some vague philosophical bullshit."
] | [
"This is just about perfect. I can nut down to the details of each of those with him relatively easily - thankyou!"
] |
[
"Why do we divide the electromagnetic spectrum into different sections?"
] | [
false
] | Did we just arbitrarily decide where the divides between say X-rays and gamma rays are? Or does energy literally behave differently at these different levels? | [
"microwaves have wavelengt roughly the size of micrometres",
"They do not. Micrometer waves are infrared. \"Microwaves\" got the name \"micro\" from being shorter than radio waves, it shares the origin of the name with the SI prefix for 10",
" but they don't have micrometer wavelengths."
] | [
"It's just a historic classification, based on the prominent experiments and application of the bands.",
"X-rays, also known as Röntgen radiation, was discovered as a typical bremsstrahlung when electrons hit certain materials. Wilhelm Röntgen called it \"X-ray\", the X standing for \"unknown\", because at first ... | [
"The ionization energy is not dependent on the way you measure it, or which units you use. It's purely based on the forces within that specific molecule. You'll get different values if you measure in eV or in J, but an alien doing the same experiment on a different planet in completely different units will come to ... |
[
"How would we know when we become homo novus and not homo sapien?"
] | [
false
] | [deleted] | [
"Defining the breaking point between two species is always a tricky business, but it usually is agreed that when two populations are no longer interbreeding (due to behavioral/genetic reasons, not geographic reasons) they can be considered separate species"
] | [
"Defining species is bad enough sometimes, but distinguishing when one species becomes another ",
" is much worse--especially when you are watching it happen and not looking at a couple of fossils seperated by 10 million years. People will draw some arbitrary line that may have little biological relevance, unles... | [
"Species aren't that terribly well defined. Reproductive compatibility is the most common criterion, but in a world of genetic medicine and in-vitro breeding, who could tell and why would it matter?"
] |
[
"Is it possible for a brain tumor to inhibit emotional response?"
] | [
false
] | I've recently taken an interest in Neurology, or more accurately, in diseases of the brain. As a result, I have been wondering if it is possible for a brain tumor (malignant or otherwise) to inhibit the afflicted party's emotional response, or ability to express emotions in general. If the answer to the aforementioned question is affirmative, in which part of the brain would the growth be located in to illicit such an affect? | [
"Lesions of the amygdala have been associated with blunted emotional responses, so if the tumor results in damage to that area (or projections to/from it), then the answer is yes. ",
"More generally, it's well-established that emotional changes can accompany any kind of brain trauma (not just tumors); a famous ca... | [
"I would guess any kind of mass growing within the enclosed volume of the skull has the potential for doing damage. The stuff in there doesn't respond well to getting pushed on..."
] | [
"Tumors which cause emotional ",
" are most commonly seen in the frontal lobe. Offhand, I'm unfamiliar with tumors near the amygdala, but it is certainly plausible that they could cause problems similar to what LabKitty described."
] |
[
"What am I hearing when I close my eyes and flex the muscles responsible for blinking?"
] | [
false
] | The sound is best described as a fairly low rumble as though a great herd of buffalo were on the move a fair distance away. It can be done voluntarily. edit:spelling. | [
"It's activation of the tensor tympani muscle, also activated when you yawn. Check out ",
"r/earrumblersassemble",
" for more info."
] | [
"The sound you are hearing is actually that muscle contracting! muscles contract anywhere from between 10 and 70 Hz (times a second) - and we can hear those twitches! When you yawn, you're hearing the muscles of your head contract. crazy!"
] | [
"Crazy indeed! Thank you both."
] |
[
"How significant is nose hair in protecting us from infection?"
] | [
false
] | It's common to see advice not to pluck nose hair because of it's supposed role in protecting us from infection. Late edit: I'll also add another reason I've posted this question; I'm 51 and my nose hairs are doing what they do in all of us after we reach middle age. If I could afford it, I'd consider permanent removal of them. Like most men my age, it's getting to the point where I could probably grow a bit of a mustache with just my nose hairs, now that they've changed the direction and length that they grow. | [
"The mucosal membranes are part of your immune system's first line of defense. Hair, mucous, and ciliated movements trap and expel foreign objects/antigens out and off the membranes and therefore out of the body. It's not that you're fucked without it, but every little bit helps."
] | [
"To follow up on this, instead of starting a new thread:",
"How well do other bodily methods prevent infection, such as coughing, sneezing, ear wax, etc.?"
] | [
"If you have a productive cough (a cough with a fair amount of mucous), you need to get it out of your system or you're just making things harder on your immune system.",
"Forgive the gruesome detail, but I imagined that after a wad of mucous was coughed up and then re-swallowed, it was leaving the respiratory tr... |
[
"Pelican found"
] | [
false
] | In Pacific Mexico, we found a bird looking like this with a smaller and sharper beak. It is seemingly lost and possibly juvenile, seperated from its family. Is there anything possible that we can do to save this bird? It stays in one place and lets humans touch it; the parents would probably reject it if found on account of the human scent. edit: Not a pelican. Went out today, and for the second day it was just standing, not caring about humans. When we got near, it opened its beak and positioned it vertically (hungry?). Please help, I have pics here! | [
"Look up for any animal shelters that take animals such as pelicans if its indeed abandoned/injured. I have no idea where you are in Mexico so you got to ask the locals and look up if there is one in the area."
] | [
"You are correct,that is a myth. WHEN is that stupid myth going to die!?ಠ_ಠ",
"I used to be a wildlife rehabber and we always had babies brought in that should have been left ALONE..But no.\"My kid picked it up and so now we are giving it to your wildlife shelter to raise cause of a tired old myth.\""
] | [
"You are correct,that is a myth. WHEN is that stupid myth going to die!?ಠ_ಠ",
"I used to be a wildlife rehabber and we always had babies brought in that should have been left ALONE..But no.\"My kid picked it up and so now we are giving it to your wildlife shelter to raise cause of a tired old myth.\""
] |
[
"In the course of Earth's history: Are separated continents less common than super-continents?"
] | [
false
] | This question only arises after I became curious about how Pangaea formed. I then saw that geologists believe there may have been four or so other super continents at one time or another. I was just curious if continents being separated (like there are in the current day) is just a transitional period before there is another super-continent or if those super continents were all created due to random circumstance? I was just curious if geologists had an idea of the frequency of each type of continent. | [
"Hi there, Geologist here:",
"Whilst I cannot comment definitively on the \"frequency\" of both (it's very difficult to work out, and there are many oppositing theories and interpretations) I can handle the rest of your question.",
"Regarding: \"or if those super continents were all created due to random circum... | [
"I see that site has geophysics in the URL thingy. Is it suitable for me to learn the very basics of geophysics in less than a week?"
] | [
"Why the same land masses for so long, just cut up and moved around?",
"Shouldn't plate boundaries be creating new continents and destroying old ones, so that there's never a single supercontinent because land is forming on the other side of the Earth just as quickly as the continents are being smushed together e... |
[
"Are there any human populations without any Neanderthal DNA? Are there measurable differences from that absence?"
] | [
false
] | null | [
"Native African tribes. Neanderthals lived in Europe and Western Asia, and only encountered humans after we migrated out of Africa. From there, we interbred with Neanderthals, and moved across the globe, first to East Asia, then the Pacific Islands and Australia, and finally North and South America. Since no human ... | [
"Since no human groups (that we know of) went back to Africa",
"... except for the ",
"Eurasian backflow",
", but your general point stands."
] | [
"Second more speculative question. What would we be like had we never interbred with them? How would that have changed history and cultures?"
] |
[
"How does sorting by \"Relevance\" work? How does a computer determine what's relevant and what isn't?"
] | [
false
] | A lot of search tools let you change the thing you sort by. You can look at the most recent, the newest, or the most popular, and I can understand the criteria they're sorting by. But sometimes you have a sort by "relevance" option ( ), and I don't understand what that's doing. And just to be specific, I'm not talking about algorithms like pagerank that can use outside information like cross linking to determine the weights of specific entries, but specifically something like reddit's search, that only has the entries themselves to determine relevance from. Unless, of course, that's how all of these relevance sorts work on the back end. | [
"A whole lot of different websites use a whole lot of different information to sort by \"relevance\". One option would be to use the amount of times someone searched the same keyword and clicked a link from that search (thus making its relevance higher). Other options would be to use the searching user's own histor... | [
"To give an example of this that happens to be open-source, we can look at ",
"Apache Solr/Lucene",
", which is pretty widely implemented on a lot of big sites for internal site searches. Each possible search result is stored as a \"document\" (in this case, probably the text content of each possible page on th... | [
"It's just a name, so don't put too much stock by it: the computer does not know what's truly relevant what's not; rather, the designers of the system have come up with an algorithm that is ",
" to find things relevant to your query, and so that's the label they put on it.",
"One popular algorithm if you type i... |
[
"Nitrogen versus carbon dioxide in beer."
] | [
false
] | Probably asked before but I can't find it. Why when you pour a beer that uses nitrogen (nitrogonated?) like Guinness can you pour straight down and get a solid head without overflowing a pint but with carbonation it will just go everywhere. Specifically what is the chemical reaction that keeps the nitrogen from expanding as recklessly as CO2. | [
"I'm pretty sure this is wrong. It might not be entirely wrong, but it is not the main reason for OP's observations.",
"Guinness doesn't \"go everywhere\" because it's only carbonated to about 1.2 volumes of gas mix, whereas most other beers are carbonated to 2 - 3 times that amount. For instance, Bud Light is ... | [
"I'm pretty sure this is wrong. It might not be entirely wrong, but it is not the main reason for OP's observations.",
"Guinness doesn't \"go everywhere\" because it's only carbonated to about 1.2 volumes of gas mix, whereas most other beers are carbonated to 2 - 3 times that amount. For instance, Bud Light is ... | [
"But they're not pressurized to the same level; that's my point. That one fact fully answers the question. Guinness has 1/3 - 1/2 the dissolved gas as most other beers. And the pressure that the bottle can handle is irrelevant here."
] |
[
"Big Bang and the accelerating universe?"
] | [
false
] | [deleted] | [
"In the explosions you mention, the initial expansion accelerates because energy is still being put in (the fuel is burning). That is not happening in the accelerated BB expansion now.",
"In your examples, the expansion slows because they are pushing against the air and losing energy to it. The BB expansion isn... | [
"My phrase \"we think\" was only referring to the inflationary epoch during the very early universe. The other two periods (of deceleration, followed by acceleration) have been observed.",
"We certainly don't know everything (we never do), but the probability that \"all we thought today about BB was wrong\" is n... | [
"keep in mind the big bang was not an explosion actually.",
"\nRather it was a sudden , very energetic expansion of the time-space continuum. I.e. there was no space-time where sth existed , only a singularity which encompassed all , space - time - matter - energy - possibly other dimensions. ",
"The BB was a ... |
[
"If a hammer is essentially made of atoms, and a nail is essentially made of other atoms, and on the outside of these atoms is an electron cloud, then is sound essentially the product of electrons banging into each other?"
] | [
false
] | I got to thinking, and sometimes things like this show up in my head. But if the outer "layer" of metal is just a bunch of atoms that have a nice pretty electron shell, then how is sound produced when nothing but electron clouds touch? How is sound different on one object than another when all elements have the same electrons? | [
"You can think of the atoms of the hammer as a bunch of weights attached to each other with springs. An illustration:",
"*—*—*—*\n| | | |\n*—*—*—*\n| | | |\n*—*—*—*\n",
"Where * is an atom with mass, and lines represent \"springs\" (the bonds between atoms). Now consider what happens if you punch one of the a... | [
"Sound is the collective vibration of matter, not of individual atoms. Vibration of electrons produces photons, but that's a different story.",
"Electron clouds repel eachother. When you force some close to another, they resist (this is why the hammer can't go through the nail). As a result, this vibration transf... | [
"If matter is composed of atoms, and atoms are mostly empty space, then why doesn't the hammer just go right through the nail!?",
"The answer is that pauli's exclusion principle prevents electrons from occupying the same quantum state. By trying to force the hammer and the nail to occupy the same space you come ... |
[
"Do you use more energy when walking up the stairs by stepping on each step or by skipping every other step?"
] | [
false
] | null | [
"Your legs are more efficient at straightening when they're closer to straight (to a point) -- this is why for example racing cyclists will set their seats so that their legs are almost straight at the bottom of their pedal stroke.",
"So the deeper knee bend when going up two at a time means you do more work for ... | [
"Posting this a reply here since it got buried under a negative comment.",
"Your legs are more efficient at straightening when they're closer to straight (to a point) -- this is why for example racing cyclists will set their seats so that their legs are almost straight at the bottom of their pedal stroke.",
"So... | [
"Posting this a reply here since it got buried under a negative comment.",
"Your legs are more efficient at straightening when they're closer to straight (to a point) -- this is why for example racing cyclists will set their seats so that their legs are almost straight at the bottom of their pedal stroke.",
"So... |
[
"Can someone help me understand the arguments around Abortion?"
] | [
false
] | null | [
"Human Body"
] | [
"Human Body"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"This question is not answerable via the scientific method. Please see our ",
"guidelines",
".",
"Please see our ",
"list of related subreddits",
" for other options for your question.",
"It ... |
[
"Psychologically, what's happening in my brain when I spin around really fast and get dizzy?"
] | [
false
] | null | [
"Its more physiological than psychological. There is fluid in your ears that (along with other mechanisms) help you orient and balance yourself. When you spin, the fluid moves outward due to centrifugal forces (ie: spinning a pizza moves the dough outward). This confuses your senses into thinking your still moving,... | [
"On a related note this is basically why you get dizzy when you're drunk. Signals are not in [relative] sync (as alcohol inhibits brain activity) and what you see is not what you feel [balance wise] and it throws you off."
] | [
"Your brain is trying to process two different signals about where it is and what it is doing. Once you stop spinning your eyes will be sending a message which should be interpreted as \" I am standing still\" at the same time the motion sensors in the inner ear are still giving the signal normally interpretted as ... |
[
"If you've lost a limb like a hand or foot, what do your muscles do when your brain sends the signal to move that limb?"
] | [
false
] | Obviously there's no hand to move but is there still muscle contraction? Will the "stump" (for lack of a better word) move slightly? Will it hurt? | [
"I don't believe that the actual question has been addressed yet. Unless I'm mistaken, the question wasn't referring to signals unable to reach missing muscles after loss of a limb. It's asking about muscles still present which at one time had a part in controlling the missing limb, EG forearm muscles after loss ... | [
"Typically called phantom limbs. So maybe searching for mirror phantom limb."
] | [
"Any source on this? Very interested and not so sure what to search for."
] |
[
"What inferences, if any, can be drawn from an unrooted phylogeny?"
] | [
false
] | I know unrooted phylogenies are a useful simplification because each one encapsulates many different rooted trees. But if you look at an unrooted phylogeny itself, with no background knowledge as to where to root it, what can you say about the taxa involved? For example, in the first image here, one might be tempted to say that we can infer that humans are more closely related to chimps than they are to gorillas. But we can’t: if the tree’s root was actually at point B (hypothetical), then that’s false. So is the unrooted tree merely an intermediate step on the ultimate journey, with no insights to be gleaned? But then how can that be reconciled with their frequent appearances in journals, and the fact that some analytical methods for unrooted phylogenies really do mean to convey information (such as the hypothetical second phylogeny linked here)? Thank you so much for your help! | [
"You actually can tell relationships on an unrooted tree, the issue is you can't tell when things happened at the sort of starting point. If your example included neanderthals for example, you'd see them branched from the same line that leads to humans. Theres still no root. We don't know whats the next closest, bu... | [
"That makes a lot of sense. Thank you. But when making inferences about relationships, isn't the only true metric of interest the time of the MRCA? So two sequences could be remarkably similar, sure, but if it only happens that way because of convergence (e.g., long-branch attraction) then they really can't automat... | [
"Well first of all you state \"time\" but in reality time isn't the best indicator of evolution. Time is an alright metric because mutations and genetic drift happen at constant rates, but under different conditions there can be faster or slower evolution of some traits in certain environments. So time is an ok est... |
[
"[Physics] Why does it take around 100000 years for the energy from the center of the sun to reach the outside of the sun?"
] | [
false
] | null | [
"THe specfici reason though, is the density of the matter the photon is going through. It takes a long time to get retransmitted from molecule to moleclue."
] | [
"It is just a typo, I'm sure, but could be a confusing one. It is fusion going on in the sun, and the typo looks like it could be you're saying fission. "
] | [
"The radiation from the sun (such has heat energy and light) reaches us in only 7 minutes. The photons that originate from the center however do not have a clear path, and they are absorbed, ejected, and reabsorbed by the dense matter in the sun. It has been approximated to take over 100,000 years for those photons... |
[
"How involved is the strong force in creating mass?"
] | [
false
] | It is my basic understanding that most of an atom's mass arises from the energy of the quarks inside nucleons. But since the strong force (via gluons) dictates how these quarks operate, how much of a hand (if any) does the strong force have in the creation of this mass vs. the sheer kinetic energy of the quarks? | [
"It is my basic understanding that most of an atom's mass arises from the energy of the quarks inside nucleons.",
"The vast majority of hadron masses is due to strong force interactions. And the vast majority of the mass of matter is from the atomic nuclei, which are made of hadrons (protons and neutrons).",
"B... | [
"The vast majority of hadron masses is due to strong force interactions.",
"For light hadrons (including everything that makes up the matter around us), but not for all hadrons. If they have a charm or bottom quark (or more than one) their mass is mainly from these quarks."
] | [
"Thanks so much! Can you offer a brief explanation of the graph?"
] |
[
"Can depression affect someone's memory?"
] | [
false
] | [deleted] | [
"Yes"
] | [
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4561348/",
" depression can induce a decrease in episodic memory, with lessen reward for positive memory recalling."
] | [
"I'm no expert but I have previously been taught about something called 'overgeneralised memory' which is, in the most basic way that i remember it, when a depressed person looks back and only recalls the memories related to general doom and gloom and misery in their life.",
"https://en.wikipedia.org/wiki/Overgen... |
[
"When I transfer data to my external hard drive using a USB cord why does the rate of the transfer constantly change (60mb/s to 90mb/s) throughout the transfer when my computer is doing nothing else?"
] | [
false
] | null | [
"There's a couple factors that can influence this.",
"Are you transferring one big file, or a whole folder full of different sized files? There's overhead to create and finalize each file written to a file system, so lots of small files will slow down the overall transfer speed.",
"How populated is the hard dri... | [
" - Think of a parking lot with a lot of small spaces. You have an SUV (file) to park (write) and these spots (empty drive storage) look empty at first but as you check it out it has a motorcycle or Smart Car parked in it, or someone parked over the line and didn't leave you enough room (there is empty space on the... | [
"HDD transfer rates vary by the location on the platter being accessed. The further towards the edge of the platter, the faster read/write will be. If the drive is constantly changing the location where data is being read/written, possibly because of bad sectors or disk fragmentation, this would account for the cha... |
[
"I know that its a myth that we only use 20% of our brains, but we use small areas during different activities. What activity can I do to use the \"most\" of my brain at once?"
] | [
false
] | null | [
"A seizure!"
] | [
"I remember seeing (a very long time ago) a 3D measurement of brain activity during various activities. This was all set up to try and show how the 20% can be BS. There were various activities of reading, watching TV and sleeping. All of those activities there wasn't much more than 20% activity or so. Then they rec... | [
"ride a unicycle while juggling and reciting pi to 200 decimal places..."
] |
[
"If Dinosaurs got extinct by a meteorite hit or a megavulcano, why didn't the underwater sea-dinos survive? (f.e. Plesiosaurus, Mosasaurus,etc..)"
] | [
false
] | null | [
"ObNitPick: Plesiosaurs and mosasaurs are not dinosaurs. They aren't even archosaurs - they are lepidosauromorphs, more closely related to modern lizards than they are to dinos & birds.",
"In something as big as the Chicxulub/Deccan traps event, marine ecosystems are going to suffer, too. First there would be the... | [
"There are two common misconceptions surrounding the K–Pg event ~65 mya: ",
"That all dinosaurs went extinct. This is not true, since birds are dinosaurs and they are alive today. ",
"Dinosaurs were the only group to experience widespread extinction. While dinosaurs are probably the most famous example of wides... | [
"Other sea creatures like sharks, fishes etc survived, so why not those?",
"I'm uncertain from how you phrased your question, but I want to point out, other land animals survived as well, not just marine creatures. The extinction event was severe but not universal. However, the only dinosaurs that survived were t... |
[
"Can cancer be contagious?"
] | [
false
] | I'm not referring to things like oncogenic viruses or infectious agents that can cause cancer; rather, if cancerous material from one individual (say a fleck of a tumor) enters another individual (say it got into their bloodstream through a cut), could it thrive in the host environment? I'm guessing the immune response would make this difficult, but given that cancers replicate so quickly and aggressively, could this happen? | [
"Almost invariably no. If you’re talking about humans, then almost never. ",
"There are four exceptions that we know of: A contagious cancer of dogs, a contagious cancer of Tasmanian Devils, a contagious cancer of clams, and a contagious cancer of hamsters that has been extinct since the 1960s. ",
"Canine trans... | [
"It's very rare, but yes. Tasmanian Devils are one such species who suffer from contagious cancer called DFTD. This takes the form of facial tumors which can be spread from one to another through biting. This is very much the exception though, otherwise you only see metastasis within a singular creature's own body.... | [
"While most cancer is not contagious, it’s important to remember that the causes of certain types of cancer are contagious. HPV is a great example which is why they have a vaccine. Further, community exposure to the same free radicals might cause a certain form of cancer seem contagious."
] |
[
"If a quantum fluctuation caused matter and antimatter to come into existence, than is it possible for it to happen again during the lifetime of our universe? A second big bang?"
] | [
false
] | null | [
"There is an idea out there called the metastable or ",
"false vacuum",
". It's not held in wide regard, but... it exists. Specifically, that when the quantum state fluctuated down to its present state, there may have been a deeper state it could have gone to, and maybe someday it could spontaneously fluctuate ... | [
"Oh, that would suck."
] | [
"So let me ask you a second question. ",
"How would we ever communicate with the other universe?"
] |
[
"In an a large asteroid or comet strike, does the angle of impact make a difference? Same with a ground vs. air burst."
] | [
false
] | Also, What if there was an impact was in deep ocean, would it make it to the ocean floor? | [
"Yes, they absolutely make a difference. Mybest advice is to spend some time playing with this ",
"http://impact.ese.ic.ac.uk/ImpactEffects/"
] | [
"The major difference that angle of impact makes is whether or not it will explode in the air. ",
"At a low angle of reentry the meteor (comets work differently) has a longer time to heat up and flatten, this flattening causes more heat to be generated and the cycle self-accelerates. It reaches a point where it c... | [
"cool link. Thanks."
] |
[
"Are there any non alternating, infinite series', that diverge slower than the harmonic series?"
] | [
false
] | The harmonic series already diverges extremely slowly, I was wondering if there were any other series' that diverge slower than the harmonic. | [
"The series Σ 1/(n ln(n)) diverges and does so more slowly than the harmonic series.",
"In fact, given ",
" divergent series Σ a",
" with positive terms, there exists a divergent series Σ b",
" with positive terms such that b",
"/a",
" --> 0 as n --> infinity. So in this sense, the series Σ b",
" dive... | [
"A series of the form Σ n"
] | [
"Suppose you give me a series that goes to infinity. Chop it up into 'blocks' that each sums up to at least 1. Now divide n-th block by n. Now each block is smaller (except for the first one) than it was, but n-th block is at least 1/n - so summing over the blocks gives at least as much as harmonic series, i.e., in... |
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