title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Is there a limit to the amount of information that could theoretically be stored in the universe? Can you store more than one bit (piece) of information using a single particle?"
] | [
false
] | [deleted] | [
"Related to your question is ",
"Landauer's principle",
" which has to do with the minimum amount of energy needed to change a bit. Essentially, the laws of thermodynamics can be used to prove that changing a bit of information requires a certain minimum amount of energy to be used. Combining this idea with som... | [
"The ",
"Bekenstein bound",
" is an upper limit on the entropy of a finite region of space, varying by its temperature.",
"As it turns out, in a certain precise way, entropy corresponds to the number of possible distinguishable states internal to the system, which is also the maximum number of states of infor... | [
"Strictly speaking, from an information theoretical standpoint, the amount of information stored in the universe is precisely zero.",
"The maximum information content of any system measured in bits is the logarithm to base two of the number of possible states the system can have (if the states do not have equal p... |
[
"Isn't it technically correct that a heavier object will fall faster than a lighter object even in a vacuum?"
] | [
false
] | Hi Isn't it true that an object also "pulls" a tiny bit on earth as well as the earth is pulling on the object? The gravitational pull from the object is obviously negligible in comparison, but wouldn't it indeed be the case(that two heavy objects will accelerate towards each other faster than one heavy and one light) ... | [
"There's a couple different kinds of mistakes in the comments here so here's some more detail, but the answer is yes; strictly speaking, massive bodies will hit each other faster than light bodies will [edit: Newtonian-ly speaking].",
"For this analysis we're going to imagine the bodies in a vacuum, separated by ... | [
"Yes, the force of gravity increases but so does the mass. The formula is",
"acceleration = force / mass\n",
"Force goes up in proportion to the mass so the acceleration stays the same. We don't ignore anything."
] | [
"You have to take into account acceleration on two bodies though, not just one.",
"Let's say we have a bowling ball and a golf ball. ",
"We can think of it like this.\nThe effect of the earth's gravity on those two objects is indeed the same.",
"If you look at it the other way, though, as the earth falling to... |
[
"Why is the atomic mass of say, Chlorine-35 known to be about 34.96885 amu, if both one proton and one neutron weigh more than 1 amu?"
] | [
false
] | It doesn't make any sense to me as a math student. I am aware that the atomic mass unit is defined by one twelfth the mass of one atom of Carbon-12, and also that a neutron weighs slightly more than a proton, but since Carbon-12 weighs 12 amu, and it has 6 neutrons and 6 protons, protons should weigh slightly less tha... | [
"The reason is that a stable nucleus has less rest energy than its separated constituents (in relativity, the rest energy of a system ",
" its mass). You have to spend energy to separate the protons and neutrons inside a nucleus, and that energy is what makes for the difference in mass."
] | [
"Another thing worth noting here is that atomic masses as reported on the periodic table are actually weighted averages of all the naturally occurring isotopes of each element. That is the primary cause of ’extra' decimal places being reported on the table. But what the above folks have said is true and accurate.... | [
"The masses of both the proton and neutron are slightly more than 1u, that's right.",
"The mass of an atom is not exactly the sum of its components masses (electron masses aside) because there are binding interactions between the protons and neutrons inside the nucleus that can stabilize it, and lower its mass. "... |
[
"Do we really have 3/4 of the fundamental forces entirely figured out? My friend in physics basically said there's nothing left to learn about them except for gravity"
] | [
false
] | null | [
"For the most part, yes. ",
"The standard model of particle physics explains the strong force, the weak force and the electromagnetic force very accurately. On option is to accept that the standard model is in fact correct, and we have solved 3 of the 4 forces.",
"There are a few problems though. while the foun... | [
"However as a physicist, I sort of do get the feeling of \"there is nothing important left to learn about the fundamental forces\" and it is depressing sometimes",
"I know what you mean, and sometimes I envy the generation of the early mid 1900s. They had the thrill of discovering so much. ",
"However there ar... | [
"Knowing exactly what the fundamental forces ARE does not mean you would know all the consequences of them. So you could continue to work to figure out how to calculate broader and more complex phenomena starting with the first principles. Additionally maybe there are alternative ways of thinking about or expressin... |
[
"Why does a green laser look orange when pointed at a magenta object?"
] | [
false
] | The laser is green on every color except magenta, where it reflects as sort of a greenish-yellowish-orange. Why? | [
"Magenta isn't actually a color. ",
"http://www.reddit.com/r/science/comments/mgrdp/magenta_is_not_a_real_color_my_mind_was_blown/"
] | [
"I saw that post, that's why I started thinking about this question. Magenta not actually being a color doesn't really explain why this happens though."
] | [
"It seems as though it would... the About.com article says that if you mix violet light and red light, you see magenta light rather than the average, which would be green. By changing the combination of colors you see, you see the combination of green-violet-red, which your brain would then presumably see as either... |
[
"From an evolutionary stand point. What is the advantage of a female eating the male after mating?"
] | [
false
] | null | [
"Nutrients"
] | [
"In the few examples I am familiar with, the female of the species is much larger than the male. They are probably more efficient hunters overall. They certainly do not need a male to provide for them while they are pregnant. "
] | [
"But surely there would be much more nutrients in the male catching prey for the pregnant female? Or are pregnant spiders not vulnerable as mammals? "
] |
[
"Will space based telescopes like Kepler, ever be able to detect artificial light?"
] | [
false
] | Specifically, is it possible, given the right technological advancements, for a telescope to identify artificial light given off on a planet by an intelligent civilization versus that reflected from the nearby sun etc... | [
"Nope. The amount of light given off by a civilization would be far less than that reflected by the star.",
"However, if it were possible, it would be hard to determine what is \"artificial.\" One way would be to look at the polarization of the light coming from the planet. Reflected starlight is isotropically po... | [
"The amount of light given off by a civilization would be far less than that reflected by the star.",
"Irrelevant if you can resolve the planet separately. This would take quite a large telescope, but it is possible."
] | [
"I love some Peter F Hamilton"
] |
[
"Are there land animals that developed with only two limbs?"
] | [
false
] | [deleted] | [
"All the animals you cited are tetrapods (\"four footed\") which are by definition descended from a common ancestor that was a four limbed vertebrate that walked (at least some of the time) on land. These animals have four limbs because their ancestors had four limbs. Therefore the condition of being four limbed is... | [
"Pythons have ",
"pelvic spurs",
" which are vestigal remains of their hind limbs. The male pythons use these spurs during courtship and mating, so they do serve a purpose and may be retained in their descendants for that reason."
] | [
"There are several lizards as well as caecilian amphibians that retain only two limbs. For the caecilians, which resembles scaled worms, they are the front limbs, and can be large and mole-like. For lizards, it's usually the forelimbs; glass lizards, skinks, etc produce legless and two legged species. However, remn... |
[
"Could someone explain in layman terms, the chemical imbalance of someone suffering from depression?"
] | [
false
] | null | [
"There's something called the \"Serotonin hypothesis\". It's controversial.",
"There are medications called SSRIs - Selective Serotonin Reuptake Inhibitors. Serotonin is chemical in the brain that's associated with things like mood and sometimes addiction. SSRIs are supposed to control how much serotonin is u... | [
"Read one of \"The Emperors New Drugs\" or \"Anatomy of an Epidemic\" to see a complete discussion of the various theories behind depressions. The respective authors suggest the science is rather tenuous. "
] | [
"Serotonin is the chemical that makes you feel happy. You do not produce enough Serotonin. If you are on anti-depresants then you probably have some form of drug that increases the avilability of Serotonin to your brain.",
"Without your exact diagnosis it's hard to provide firm information, and with your diagnosi... |
[
"attention deficit disorder: inherited, or environmental conditioning?"
] | [
false
] | I know this is a hot question that's been thrown around the internet more than a billion times, but I want to learn what the current popular perspectives are. | [
"Currently we understand that ADHD is mainly inherited from parents, though there is also some environmental factors that get flagged from time to time. The authenticity of those is beyond my qualification, as they aren't my level of research. ",
"Things such as parenting and diet have been proven through researc... | [
"I just finished a research paper on ADHD a few days ago. This was the best source I had. Maybe I'll post my paper later.",
"http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7610.2012.02611.x/full"
] | [
"I'd be interested in reading that, if you can share it. What was the focus of the paper?"
] |
[
"Would balls placed randomly on a smooth rotating planet tend to roll toward the equator?"
] | [
false
] | null | [
"This is true for a rotating sphere with no gravity, but the OP asked about a ",
". A realistic rotating planet would deform due to the rotation until it is in hydrostatic equilibrium. So it would become an oblate spheroid and the entire surface would be an equipotential for gravity+centrifugal. (Let's ignore any... | [
"This is true for a rotating sphere with no gravity, but the OP asked about a ",
". A realistic rotating planet would deform due to the rotation until it is in hydrostatic equilibrium. So it would become an oblate spheroid and the entire surface would be an equipotential for gravity+centrifugal. (Let's ignore any... | [
"(I'm trying to keep this as nontechnical as possible so the OP and other readers can follow it: bear with me, math geeks.)",
"You don't need any fancy math. Let's start by imagining a water-covered planet. If the water surface had a \"downhill\" anywhere on the planet, then the water would flow \"downhill\" to... |
[
"Is the relationship between dental hygiene and overall health causation or only correlation?"
] | [
false
] | I've read a few times that there is evidence linking good oral hygiene to better health overall and less likelihood of developing some serious illnesses later in life. My question: is the reason that having a cleaner mouth might make you actually be less likely to get sick, or is it merely that people who take good car... | [
"I'm asking about the relationship between oral hygiene and overall health, particularly certain diseases like heart disease and diabetes, which to me do not have any obvious intuitive connection to bacteria in the mouth. ",
"I've read it elsewhere but here is a link to ",
"wikipedia",
" showing the diseases ... | [
"Gum disease can lead to bacteria in the blood, and can cause endocarditis."
] | [
"This. Chronic exposure of bacteria into the blood will cause systemic low-level inflammation. Excess inflammation in turn is known to cause all sorts of problems.",
"The body makes every attempt to seal the blood stream off from external bacteria sources. There are only two places where these barriers are suscep... |
[
"A question for the social scientists and neuropsychologists especially, with regards to what we've learned about the brain in the last 1-2 decades, what would you do to improve society?"
] | [
false
] | null | [
"Just posting a reminder that answers should be SCIENTIFICALLY based and reasoned. Cite your sources! The OP is specifically asking regards to what we know about human neurology and its interaction with sociology."
] | [
"I would change the ages at which teenagers/adults make decisions and have access to various choices. We know a lot more about the development of the brain than we used to - and because of that there are some 'age of majority' and 'age of consent' issues in a variety of different contexts. The ability for most teen... | [
"The criminal justice system relies heavily on eyewitness testimony, which has been shown to be unreliable, and even manipulable. People can not always be trusted to correctly remember events, especially as they get more traumatic, and when the witnesses are children.",
"This NY times article",
" talks about st... |
[
"Are there actually any places that are zero-gravity?"
] | [
false
] | Being outside of Earth's orbit qualifies as "zero-gravity", but that's still orbiting the Sun. Of course, you're not in traditional gravity, i.e., being pulled to the centre of an object, but you're still being affected by the gravity. Let's say you leave the orbital reach of our sun. You aren't being affected by the g... | [
"Gravity exists in every corner of the universe. Each particle has a force of gravity exerted on it from every other particle in the universe. The strength is extremely insignificant. This can be illustrated by the equation for universal gravitation: F=GMm/r",
" where G is 6.67x10",
" M and m represent mass of ... | [
"I don't think that this is really correct.",
"Firstly, the big bang did not occur at one single place, so your premiss is faulty to begin with.",
"Secondly, and perhaps more importantly, due the metric expansion of space the distance between two given objects in the observable universe may increase at a rate m... | [
"I don't think that this is really correct.",
"Firstly, the big bang did not occur at one single place, so your premiss is faulty to begin with.",
"Secondly, and perhaps more importantly, due the metric expansion of space the distance between two given objects in the observable universe may increase at a rate m... |
[
"Can vaccinated individuals transmit the Delta variant of the Covid-19 virus?"
] | [
false
] | What's the state of our knowledge regarding this? Should vaccinated individuals return to wearing masks? | [
"You want to stay away from binary, yes/no questions. The answer is almost always yes, but...",
"Even before variants came along the vaccines weren't 100% effective. Some small number of vaccinated people got sick, some even died.",
"Some vaccinated individuals can, to some extent transmit disease, but vaccina... | [
"You got it. I don‘t understand why people always turn a „we don‘t know because there is no data and we didn‘t look into it especially“ turns into a „it‘s not working“\nFrom the general understanding of the immune system it is very unlikely for an vaccinated individual to be able to transmit a disease IF the vaccin... | [
"As far as I know this hasn't been directly looked at. The delta variant may be slightly (but only slightly) more resistant to vaccine protection. For example, with the Pfizer vaccine efficacy went from ",
" - a barely significant or not significant difference (",
"Effectiveness of COVID-19 vaccines against the... |
[
"Why are some oxidized compounds highly energetic?"
] | [
false
] | I've always associated highly reduced, long chain compounds as the most energetically dense. Compounds such as fatty acids, alkanes, and sugars all make sense to me as being energy rich. Occasionally though, I'll find that things I would not associate with high energy content are explosive. I don't understand for examp... | [
"A redox reaction takes an oxidation ",
" a reduction. That is, a reduced thing and an oxidized thing. The more highly reduced and the more highly oxidized the two reactants are, the more energy they release as they head towards the middle. ",
"Usually dioxygen is the oxidizing agent so energy = source of re... | [
"I've always associated highly reduced, long chain compounds as the most energetically dense.",
"Probably because that is true in biological compounds - especially with regards to photosynthesis and respiration and the metabolic pathways involved. However, one must keep in mind that there is the other half of the... | [
"One way to examine the stability of a compound is steric strain - and this is a common qualitative way of examining a molecule or reaction intermediate in organic chemistry.",
"Another way is to look for activated functional groups. N-Nitro groups, for example, tend to react violently if you look at it the wrong... |
[
"Is there such a thing as a \"collapsible\" polyhedron?"
] | [
false
] | So, I've been looking into some definitions of polyhedrons and, basically, I'm wondering if there is a type of polyhedron that would be "collapsible". I'm sorry for making up a term but I don't know how else I can describe the type of polyhedron to which I am referring. Basically, I'm defining "collapsible" as a proper... | [
"There is something called miura-ori origami that has the properties you describe. ",
"https://www.youtube.com/watch?v=sUyTAgTHmwE#t=1455"
] | [
"I think a way of wording what you're talking about, and forgive me if I'm wrong, is that the interior angle between any edge is free to change, but the other properties (number and size of faces) remain constant."
] | [
"Wouldn't any regular polygonal prism with an even number of edges would fit your criteria of being \"collapsible\"?",
"Examples: a cube, a hexagonal prism, an octagonal prism etc."
] |
[
"How much sunlight can you put through optical fiber?"
] | [
false
] | [deleted] | [
"Ok. There are several factors that control how well you will do. The first is, of course, if you focus it and melt the fiber. That won't work!",
"There are two types of fiber. One is single mode, which is the kind used to carry internet. The reason is that, the other type, multi-mode, allows more than one distri... | [
"I'd guess it'd take a while before you have to think about destroying the fiber due to too high optical intensities, the material is really pretty transparent at most optical frequencies, see eg here for a commerical product: ",
"http://www.thorlabs.de/NewGroupPage9.cfm?ObjectGroup_ID=362",
"I'd suspect the bo... | [
"What about concentrated light like in laser form? Or higher energy light such as X-rays?"
] |
[
"How do migratory birds who fly huge distances keep track of all the different predators and edible/non-edible foods they might encounter on their journeys?"
] | [
false
] | Some birds fly thousands of miles on their migrations and it seems to me that these birds would need to keep track of lots of different types of food sources, as well as being aware of threats posed by different predators, and other dangers, along the way. Is it all just inherited memory or instinct? Or do the younger ... | [
"Migration is complicated and operates off several different mechanisms, many of which we don't really understand very well yet. Different species of bird also handle migration differently, so there's no one size fits all answer.",
"In general, migration is expensive. Predation rates are high and dangers from wea... | [
"After following the birds’ migration south from Sweden to central Africa using tiny tracking devices, Swedish scientists found that the birds fly nonstop over a distance of around 4,200 miles (6,760 km) at a phenomenal 60 mph (97 kph)."
] | [
"Are those great snipe numbers accurate? That's a speed of like 50-100km/h for days"
] |
[
"In what ways do sperm change as someone gets older? Or will a 15y/o produce basically the same offspring as a 60y/o (disbarring fertility issues)"
] | [
false
] | null | [
"Consistency may change with aging and prostate either making more or less seminal fluid. Sperm are made all throughout life. It's possible that a random genetic mutation could happen sometime through life that would change the genetic makeup of the sperm as well (lead apron at the dentist) depending on hormone lev... | [
"Older fathers have more mutations in their sperm, see: ",
"https://genomebiology.biomedcentral.com/articles/10.1186/s13059-016-1110-1",
"Most of these are harmless but rarely they can cause problems if an important gene is mutated."
] | [
"Research has shown that the methylation pattern of sperm changes with age. Methylation is an epigenetic phenomenon which determines whether sequences of DNA are active or silent. The methylation changes are observed in sequences thought to affect neurodevelopment (increasing the risk of autism and schizophrenia) a... |
[
"Why is it that we cannot analytically solve some integrals like for the normal function and have to do it numerically?"
] | [
false
] | [deleted] | [
"One thing to note here is that the ",
" of an integral is \"the area between the function and the x-axis\" (ok, the real definition is a little more technical than that, but the main idea is the same; if you remember Riemann sums from your calculus class, ",
" is the real definition of the integral",
"It is ... | [
"The issue simply put is that there are functions without an elementary anti-derivative. For our purposes, a function is ",
"elementary",
" if it a combination of x, log, constants, exponentials, closed under addition, subtraction, division, multiplication, and composition. Note that we get trig functions from ... | [
"What exactly constitutes an analytical solution or closed-form solution is subjective and arbitrary. Take for example the differential equation dy/dx = y. Most people will say that this equation has an analytical solution, the exponential function. But what exactly ",
" the exponential function? It can be define... |
[
"Will frequently donating blood lead to any negative long term effects?"
] | [
false
] | I try and donate blood (plasma/platelets/red blood cells) about once a month. I am happy to donate but have a slight concern I could be putting myself at risk for something long term. I understand there are some short term side effects when donating blood, but are there any studies suggesting that frequently donating b... | [
"Plasma is mostly water, which can be replenished quickly. Platelet counts replenish very quickly too. That's why you can do plasma and platelet pheresis fairly frequently.",
"Red cells take longer to regenerate, which is why you're usually only able to donate once every 8 weeks or so.",
"If you meet the physic... | [
"I don't think this is quite what you meant, but it is an effect which can be argued as negative. My dad was a regular blood donor from the time he was in the Army in his early 20s; he's in his 70s now, and was still donating regularly until recently. He'd noticed that getting the needle in his arm had been getti... | [
"Used to work for blood and transplant in the UK, can confirm we had plenty of donors on their 60th+ donation come through while I was there. All happy healthy people.",
"Normally there is a defined period after you give that you should not attempt to give again during - in the UK we refuse to book you for anothe... |
[
"End the wasteful tyranny of reviewer experiments? Can the review process be changed?"
] | [
false
] | null | [
"This isn't appropriate to this subreddit, I'd suggest ",
"/r/scientists",
" or ",
"/r/askacademia",
"."
] | [
"Thanks, and apologies! I'll delete it presently."
] | [
"Not sure if the deleting worked, please feel free to ax it on your own accord. "
] |
[
"How do sewers transport waste?"
] | [
false
] | In my town they are adding a road and i have seen the pipes for the new section of sewer system. I see the concrete pipes and wonder how all the waste gets to the processing plant. It would make sense for it to go downhill, but I don't think you can build all plants at the lowest point in the area. Someone more qual... | [
"In general, sewer systems are designed to flow due to gravity. On the contrary, treated water systems exclusively use pressurized systems to move water. Pressurized systems for sewage are not desirable because the potential for pipes to break/rupture. You wouldn't want pressurized sewage shooting up into your stre... | [
"Keeping sewage pipes atmospheric is also a risk mitigation against sewage leaks into groudwater. "
] | [
"Desirable? Yes, gravity is free. Practical? Not in many cases. As described already sewer collection networks are almost always gravity. In a perfect world this would continue all the way to the wastewater treatment plant. In reality this is very rare. What will typically happen is the gravity collection li... |
[
"Would a male and female be able to improve their future children's DNA by exercising, not smoking, eating properly, prior to conceiving?"
] | [
false
] | null | [
"There is a growing body of evidence supporting the relationship between ",
"epigenetics",
" (heritable changes in gene expression that don't involve changes to the actual sequence of the genomic DNA) and environment (i.e. with the current data, it is possible to hypothesise that by changing habits/environment,... | [
"Most of the influence of parent to child in obesity is from the passing down of habits. You don't pass down your overactive adipose, but you do pass down the cake.",
"I'm not saying that you can be a fat and unhealthy slob and have your children fine (I really don't know how 'conclusive' the science tends to loo... | [
"FWIW, I have seen in my field (nutrition) some evidence that methyl donors such as choline can beneficially influence descendents. The mechanisms of action are above me at the moment, but ",
"here",
" is a review on the topic and a more applied ",
"study",
"."
] |
[
"How is the Doppler effect different for sound vs light waves?"
] | [
false
] | I made a bet with a friend of mine on this (I said they were somehow a little different), but everything I'm reading online seems to support his side. I did manage to dig up a sentence from Lawrence Krauss' "A Universe from Nothing" where he says that "It turns out that the same phenomenon occurs for light waves as sou... | [
"They are mostly the same with a few subtle differences.",
"With sound, it matters how fast the emitter and observer are both moving with respect to the medium. With light, it only matters how fast they are moving relative to each other. With light, things can be moving fast enough that the relativistic Doppler e... | [
"Einstein actually gave ",
"a great example",
" of this when he wrote about Relativity for the \"common folk\" ;) ",
"There are some significant differences between the Doppler effect for light and that for sound. The most obvious one is that if something is approaching you at a speed higher than the speed o... | [
"You seem to be confusing the usage of the word \"transverse\" in this context. The word transverse as used here does not refer to what type of wave is present, but to the position of the observer relative to the direction of propagation of the wave. In principle, sound ",
" experience a transverse Doppler shift.... |
[
"Plasma Balls?"
] | [
false
] | Hi...I am 12 years old, a seventh grader, I really like science, and am using my dad's account. I have a science question and he said you people would be able to answer it. Thank you for helping! So, here goes: If you have a plasma ball and you put your hand directly on top of the ball, a string of plasma connects to y... | [
"Thank you for replying!! When I turned the plasma ball on its side and put my hand on the top, furthest from the ground, the string of plasma was solid just like it was when it was on the previous \"top.\" When I put my hand on the new \"side,\" the string was inconsistent, like how it was on the old \"side.\" So ... | [
"Thank you for replying!! When I turned the plasma ball on its side and put my hand on the top, furthest from the ground, the string of plasma was solid just like it was when it was on the previous \"top.\" When I put my hand on the new \"side,\" the string was inconsistent, like how it was on the old \"side.\" So ... | [
"No need to doubt your expertise; you are, of course, correct. ",
"I use plasma globes frequently for demos at open days and this is is one of the questions that is good for prompting thought, \"Why is this plasma filament unstable and this one stable?\".",
"So definitely a very good question to ask.",
"edit:... |
[
"What evidence is there for the existence of quarks?"
] | [
false
] | I know this might sound like a stupid question, since there are considerable amounts of evidence for quarks (interactions which would be impossible without them, etc), but is there any direct evidence for quarks? I ask this because SEMs and TEMs don't have the resolution to image them, and thus observing them seems imp... | [
"This is a great question! There is no camera or microscope powerful enough to actually 'see' a quark. This is for two reasons: (1) Quarks are the smallest non-pointlike particles we know of and (2) a single quark can never be isolated. It's the second point that causes more of a problem. The thing about quarks is ... | [
"Classical theory suggests that elementary particles are fundamentally pointlike, yes. However, quantum mechanics changes things ... and it's no longer as simple as \"pointlike or not,\" rather, particles' wave functions are spread out over all of space, with an amplitude that rapidly decreases with distance. It ... | [
"The most conclusive pieces of evidence for the existence of quarks are the results of ",
"scattering experiments",
"."
] |
[
"Are computer AIs like Alphago deterministic? Or do they use some form of RNG to decide between equally valid strategies?"
] | [
false
] | [deleted] | [
"AlphaGo uses a technique called Monte Carlo Tree Search. This is a method to evaluate board states. The computer plays a bunch of random games from a given board state and, depending on who won those games more frequently, assigns it a score. There's a lot of clever pruning happening with the neural network but th... | [
"Monte Carlo is actually a much more specific method of estimating various values by sampling (taking random points and checking a condition).",
"A simplest example of Monte-Carlo technique would be as follows: suppose you have a geometrical figure, drawn on a piece of paper. You want to find the area that it cov... | [
"Conputers are fundementally deterministic, of course any program can have randomness if a good entropry source is used. However OP never said computers are not deterministic, he meant this program specifically needs some randomness because otherwise if a working strategy to beat it is found then that can be reused... |
[
"What actually causes the \"weightless feeling\" in your stomach when you are falling?"
] | [
false
] | [deleted] | [
"The weightless feeling is ",
" weightlessness caused by a lack of force on any part of your body. All acceleration terms cancel out because you're in a moving reference frame equal to the gravitational acceleration. It has to do with ",
"relativity",
", the same reason why astronauts in orbit experience no g... | [
"I don't think you need to invoke relativity at here: classical mechanics is sufficient.",
"When you are standing on the ground, gravity is exercising a downward force directly on all of your parts. The ground is exercising an upward force on the bottom of your feet, which is transmitted indirectly to all of your... | [
"Very much so. In fact, some tend to ",
"spend their first few days in space sick",
"."
] |
[
"if the earth split into pieces, would the atmosphere stay with the pieces?"
] | [
false
] | null | [
"It almost certainly depends on how the earth is getting split up."
] | [
"well specifically, open ended hypotheticals like this are just tough to answer without more detail. If we are magically dividing the earth into chunks and pulling them apart, sure then the atmosphere can come along for that ride. If it's being blasted apart by an impact, it's really hard to say what exactly an imp... | [
"Some maths, but without a final conclusion.",
"[1] Mass of Earth is about ",
"6*10",
" grams",
".",
"[2] Mass of Earth's atmosphere is about ",
"5*10",
" grams",
".",
"[3] Air density is about ",
"0.001275 grams/cm",
".",
"[4] Hence the atmosphere has a volume of about [2]/[3] = about 3.9 x... |
[
"Is Sound Heat?"
] | [
false
] | Basically, if sound is a vibration that travels through a medium and heat is the average kinetic energy of the molecules in a substance, isn't sound a temperature? Edit: A better way to phrase this question would be, is the speed at which sound propagates through a medium the same speed at which heat propagates through... | [
"The best way to think of it is that heat is random motion and acoustic waves are concerted motion in a given direction of propagation."
] | [
"Heat is defined as energy transferred due to a temperature difference, so no. (What you describe as heat is instead called \"thermal energy\" outside colloquial use, to avoid confusion.)",
"One clear practical difference is that sound obeys the wave equation (it propagates at well-defined speed without loss of i... | [
"No sound is not heat. There are certain scenarios where they are related, such as focused ultrasound heating, and an extremely low temperature phenomenon where heat propagates like sound."
] |
[
"Whats the difference between fire and plasma?"
] | [
false
] | People have described some fires as plasma, but is all plasma a fire? I guess more specifically is a plasma cutter a flame? | [
"Plasma is just gas where some of the electrons have been knocked off so that it becomes electrically conductive and responsive to magnetic fields. Fire can produce a plasma, but most of what you see when you look at a campfire is actually leftover carbon particles from incomplete combustion that have been heated ... | [
"There are a lot of misconceptions about what a plasma is. An analogy I often provide is that a plasma is to gas as a metal is to all other solids. The free electrons in metals or in plasmas give either many unique properties. When you see a \"plasma flame\" you are really seeing the electromagnetic field being exc... | [
"If you want to take a closer look at actual plasma, just turn on a gas stove or a bunsen burner. The bluish flame comes from electrons moving around in the orbitals of unstable reaction intermediaries like CH and C2.",
"I strongly suspect this is wrong. Fluorescence from gas-chemistry isn't stripping electrons... |
[
"How do waves pass through each other?"
] | [
false
] | Assuming there are countless waves passing through the air in front of me - television broadcasts, mobile phone messages, telephone calls, background radiation etc, how can they occupy the same area of space? Do the photons collide or pass through each other? Are the waves vibrating at different velocities, and why don... | [
"An electromagnetic wave is made of an electric field and a magnetic field. Both are vectors. The components from different waves add like vectors when they are in the same place. This is why you get constructive or destructive interference in things like the double slit."
] | [
"So wave A is heading from the west and passing to the east at a frequency of 90Hz.",
"And wave B is heading from the east and passing to the west at a frequency of 45Hz.",
"They cross at point C. Is the electric field at point C simultaneously moving like wave A and wave B? How can they pass through each other... | [
"At point C it would look like ",
"this",
" as a function of time. ",
"It doesn't travel through a medium, it's just an electric (and magnetic) field getting bigger and smaller.",
"A vector is something with both magnitude and direction."
] |
[
"Does modern medicine account for the majority of the life expectancy increase (not counting child mortality)?"
] | [
false
] | More specifically, say the life expectancy is roughly 80 years old in some developed country, what would that number drop to if we took away all modern medicine advances since the 1900s (excluding child mortality)? | [
"The big breakthroughs leading to increased life expectancy over the last century include;",
"Here",
" is a good breakdown on what used to kill people 100 years ago when life expectancy in rich nations was 40 vs today when it's 80. ",
"Note that if you survived birth, childhood, didn't get taken out by an inf... | [
"Pasteurization of milk is a huge thing in lowering child mortality. Not sure if we'd call that \"medical advancements\" or not. Also much better access to food; but that might have swung the medical pendulum the other way with much higher obesity rates in developed countries."
] | [
"This nifty chart qualifies this rosy assessment somewhat- ",
"https://www.infoplease.com/us/mortality/life-expectancy-age-1850-2011",
"From the 1850s through 1900, a ten year old, twenty year old, or thirty year old would be expected to live to about 60. Newborns had an expectancy of only 40-50, so most of the... |
[
"Until the discussion about SARS-CoV-2, I had no idea you could be infected by a virus and yet have no symptoms. Is it possible that there are many other viruses I've been infected by without ever knowing?"
] | [
false
] | null | [
"Yes. Just for example HPV and Herpes strains can be carried and transmitted for many years while someone is showing no symptoms, and that’s just STIs. Nearly every virus has examples of carriers who don’t know they get it and may further transmit."
] | [
"Not just viruses, but bacteria, too. There is the legendary case of ",
"Typhoid Mary",
", who was a household cook who was infected with the bacteria that causes typhoid fever but never showed any symptoms. She kept infecting the families she worked for and refused to acknowledge that she was making other peo... | [
"Yes, there are some viruses that seem to be completely symptom-free, though they are the exception, not the rule. More common are viruses that occasionally cause symptoms, where “occasionally” might range from one in a thousand all the way up to 100%. ",
"The classic examples of symptomless viruses are spumaviru... |
[
"What would happen if we exploded the worlds nuclear stockpile at the core of the Earth?"
] | [
false
] | null | [
"My wife works for a coal mining company. During a recent blast the charges went off in unison rather than in a cascade like they were supposed to. The explosion in Wyoming was detected by seismographs in Japan. I thought that was cool. ",
"Edit: ",
"http://billingsgazette.com/news/state-and-regional/wyoming/w... | [
"The total yield of all the nuclear weapons ever built would be on the order of 3-4 gigatons. That's very small. We'd perhaps pick up a disturbance of some kind, since seismology has gotten good at picking up fairly subtle effects, but that would be about it.",
"The energy would be equivalent to a rather large ... | [
"Everyone, this thread got off to a terrible start. Remember, this isn't the place for pet hypothesis, half guesses, anecdotal evidence, and baseless speculation. Keep it sourced, keep it cited, keep it scientific. "
] |
[
"Why did it take so long for humans to discover dinosaur fossils?"
] | [
false
] | People have been digging since the dawn of the shovel. I'd think that thousands of years ago, someone would have dug up enough bones to identify a ridiculously big lizard. | [
"Where did you think the dragon mythology came from? "
] | [
"They actually had been discovered, but nobody knew what they were.",
"http://en.wikipedia.org/wiki/Dinosaur#History_of_study"
] | [
"So is the question how long it took them to discover it or how long it took for a person who discovered it to pass on the knowledge that they did discover it to our current day and age?"
] |
[
"How does Hawking radiation cause a black hole to evaporate? Why don't as many particles as antiparticles fall into the event horizon?"
] | [
false
] | null | [
"So, this whole business of (anti)particles falling in and particles escaping isn't actually supported by the calculations that predict Hawking radiation (at least, as John Baez puts it ",
"here",
", \"I've never seen how the standard computation can be transmuted into one involving virtual particles sneaking o... | [
"AFAIK, the same number of particles and antiparticles are emitted by Hawking radiation. But both particles and antiparticles have mass; when they escape the black hole they take this mass with them. So the black hole is left with slightly less mass than it had before. This continues until the black hole's mass is ... | [
"This probably answered my question, but it has raised new ones for me. The description Baez gives is fairly complex, so I suppose I will need to know more in order to understand it."
] |
[
"Why do the blades on my oscillating fan look like a boat prop instead of an airplane propeller?"
] | [
false
] | null | [
"They're designed for maximum ",
" of air, not maximum ",
" of air."
] | [
"Also, they are designed to be quiet."
] | [
"This is probably even more important than my point."
] |
[
"What causes the blur that we see over hot surfaces?"
] | [
false
] | I was wondering what that distortion or blur is that we see above things that get really hot, but have no open flame. | [
"Wow. So this affect is generated when the density is varied? Would I he correct in assuming that placing the heated object in a room of the same temperature would not cause any blur or distortion? Thanks for answering btw."
] | [
"Wow. So this affect is generated when the density is varied? Would I he correct in assuming that placing the heated object in a room of the same temperature would not cause any blur or distortion? Thanks for answering btw."
] | [
"This is called the Schleiren effect"
] |
[
"Proteins in cells"
] | [
false
] | Why is it important for cells to control the amount of proteins in them? As well, how do cells even do this? I'm doing a "guided reading" (see: nothing related to our assigned reading in our textbook) for my AP biology class, and these two questions have me stumped. I can only guess why, and I would rather not err. For... | [
"Cells are extremely complex machines, so variations in the amount of proteins can create huge differences in how those machines work. Gene regulation is something we still don't fully understand, and we're still discovering new methods the cell uses to regulate genes.",
"A classic example is the gene for lactase... | [
"These answers cover the control of production of proteins well, but another process cells regulate is the destruction/down-regulation/elimination of proteins.",
"There's a class of enzymes called E3 ubiquitin ligases which can add the small protein ubiquitin onto proteins. Ubiquitin can be added onto another ubi... | [
"Thanks for the reply. Your example wit lactase really helped me understand the whole process with gene regulation more and the whole protein level issue I was having. "
] |
[
"[[Astronomy]] Why can total solar eclipses last for longer than 3 hours 27 minutes when that is how long it would take for the moon (and its shadow) to travel the distance across the diameter of the earth?"
] | [
false
] | Would really appreciate an explanation Moon roughy travels at 2288mph and diameter of earth is roughly 7912 miles. 7912 / 2288 ≈ 3.45. 3 hours + (0.45 x 60)minutes = 3hrs 27mins. But according to this website: , the total solar eclipse on the 21st of August 2017 lasted, across the earth, 5 hours. Why does this happen? | [
"You haven't factored in the width of the Moon or its shadow. The centre of the shadow passed at the speed and duration you calculated, but the shadow, the umbra and penumbra, is thousands of miles wide so it takes longer for the whole shadow to cross the Earth's surface."
] | [
"That 5 hours includes the penumbral, partial eclipse time. Looking at the table near the bottom of your site:",
"First location to see the partial eclipse begin Aug 21 at 15:46:50 ",
"First location to see the full eclipse begin Aug 21 at 16:48:34 ",
"Maximum Eclipse Aug 21 at 18:25:35 ",
"Last loca... | [
"That was an annular eclipse, in which the Moon doesn't entirely cover the Sun because it's farther from the Earth than usual. The orbital velocity of a moon is slower when it's farther away: in this case, by almost 10%.",
"That's enough to explain the \"extra-long\" 2010 eclipse, but in addition, as ",
"/u/kk... |
[
"Can a cylindrical magnetic field be easily created that drives positively charged particles inward towards the center axis of the cylinder?"
] | [
false
] | For elaboration, lets say that we are accelerating an atomic nucleus in a solenoid, like a bullet in a gun. Can a mangetic field be created around the solenoid that drives the atmoic nucleus towards the center of the solenoid (gun barrel)? | [
"Not with a static magnetic field, since magnetic field lines must be continious and point from N to S, and in your setup the center axis would be a monopole (which don't exist).",
"You can do it with alternating magnets though, just like how the LHC does.",
"A charged wire would work to draw everything in towa... | [
"I take it the corkscrewing radius is determined by the charge and the intensity of the magnetic field?"
] | [
"and the mass of the particle"
] |
[
"Does sunburn actually make skin radiate heat?"
] | [
false
] | null | [
"this is because of the increased blood flow from your body trying to heal the area - not actually the burn itself making you hot. (same is true for the red color - which is why sunburn can sometimes take a few hours to turn red)"
] | [
"Yes. The bodies internal reactions to the damage of the sunburn necessitate higher work rates and internal changes to enable the cells to repair the body. I.e., temperature is raised in accordance with the wound response, bringing in the necessary motion and reaction of required cells. This includes increased bloo... | [
"Sun exposure in long periods of time are not something most industrialized humans are used to. Sun exposure not only damages the skin (which requires repair and thus energy) but it also leads to an imbalance because of an excess of substances produced by sun exposure (leading to muscle acidity). It also can cause ... |
[
"Is there any technology utilizing the strong and/or weak forces?"
] | [
false
] | Pretty much every technology I can think of(except maybe nuclear bomb or nuclear power) rely on electro-magnetic and/or gravity to work. Is there any that uses the strong and/or weak forces? If not, could you conceive of one? | [
"Household smoke detectors depend on the weak interaction."
] | [
"Um. No. Just owning a house. Each smoke detector includes a tiny amount of radioactive material. Any particulate matter passing through the detector gets ionized, which allows a current to flow between two poles, which sets off the detector."
] | [
"Radiation therapy often uses beta-decaying nuclei (weak force)."
] |
[
"Do fish feel gravity?"
] | [
false
] | Assuming fish are neutrally buoyant, do they even know gravity exists? I would guess that water pressure would be a bigger indicator on what depth they are at than gravity. | [
"If fish are the same density as water (they seem to be nearly so), they would indeed never feel gravity at all. What an interesting question!",
"That said, let's wait for an expert to tell us if they are in fact equal in density to water.",
"Water varies in density according to temperature as well, which bri... | [
"To put it in a bit of different terms:",
"Fish do experience gravity, but they also experience buoyancy. These forces cancel one another out, resulting in a net zero force. ",
"So their buoyancy cancels out gravity, allowing them to stay at the same \"altitude\" in water. Similarly, we humans experience a forc... | [
"Well that's kind of what I thought. But I wasn't sure if that was correct."
] |
[
"Why doesn't the immune system of a chimera animal not attack itself? Shouldn't different cells with different genetic code in the same body trigger some type of immune response?"
] | [
false
] | null | [
"Many animals have a process through which the immune system learns what is self and non-self.",
"\nAs \"baby\" immune cells mature they are given a test against a collection of cells. If the baby cells react, they are killed off - they failed the test. If the baby cells do not react, they pass, and can mature ... | [
"Chimeric individuals develop both ",
"central tolerance",
" and ",
"peripheral tolerance",
" to 'self' antigens. ",
"One example of central tolerance is ",
"negative selection",
" in the thymus gland to remove T-cells that react with 'self' antigens. T cells undergo ",
"VDJ recombination",
" to... | [
"CodonAUG seems to have it just right, but I will add that not much is known about the etiology of autoimmune disorders. It's not known why exactly animals occasionally fail to distinguish self from non-self, and finding out is one of the big goals in immunology right now. We will have to figure this out before you... |
[
"Where did the cosmic dust come from to create the first stars?"
] | [
false
] | [deleted] | [
"When matter formed about 13.7 billion years ago, the universe was about 80% hydrogen and 20% helium. The original stars formed from there. You only need hydrogen to make a star. ",
"You need the cosmic dust created in novae to form solar systems."
] | [
"Cosmic dust (heavier elements) is not a necessary requirement to form stars. The very first stars basically ",
" mainly consisted of hydrogen. Hydrogen gets fused to heavier elements like helium. And after the end of the life of these stars the next generation is formed of the dust of the previous one. So, they ... | [
"Start ",
" —> ",
"https://youtu.be/wNDGgL73ihY",
"This channel (‘in a nutshell’) is great for physics stuffs so check out their videos on stars and black holes next. They answer your question simply with pretty animations.",
"‘One minute physics’ also has a great video on your question as well. Plus, Neil... |
[
"Is there a blob of particles that only loosely interact with matter at the 'bottom' of gravity wells, such as Earths?"
] | [
false
] | I know there are particles out there that don't have very many interactions with the EM field and the Strong field, like Neutrinos, which are more or less only affected by gravity. I know Neutrinos are very short-lived, but if they were longer, they would collect eventually at the bottom of gravity wells, in the center... | [
"Neutrinos are generally very long lived - we observe a background of neutrinos from the very early universe. But they don't collect at the bottom of gravity wells, precisely because they don't interact much with other forces. It takes friction (or some other force) to slow something down, an object will otherwise ... | [
"we observe a background of neutrinos from the very early universe",
"We expect it to be there but it hasn't been measured yet. We can see indirect effects of the neutrinos on the cosmic microwave background - but that was the very early universe. ",
"PTOLEMY",
" is a proposed experiment to measure the cosmic... | [
"Neutrinos are expected to be stable as there is no plausible decay mode for them. There are no lighter leptons.",
"For some types of dark matter particles and for some parameter ranges it is expected that a few accumulate in the cores of heavy objects: They fly in, some interact with something there (rare but po... |
[
"Is there more or less energy required to maintain temperature inside a cooler, depending on how much mass (stuff) is inside the cooler?"
] | [
false
] | To better explain and be more specific... We have an ice cream food truck. We are trying to mitigate damage in case our storage freezer breaks or loses power. We have some really "high tech" freezer packs that we're going to put into the freezer, so if the power goes out, the freezer packs keep the temperature as close... | [
"OK, I'll keep this qualitative and generalised (so be aware there are exceptions to some of this).",
"Chilling is generally a problem of removing energy. Here you're problem is keeping thermal energy away from your goods once they are already cool.",
"Gasses don't like conducting heat, but can do convection. S... | [
"yeah, a weird part of thermodynamics is separating heat and temperature in your head. heat is a measure of all the energy contained, temperature is a measure of how bad the heat wants to spread somewhere else. ",
"If you have more mass in there it can hold more heat before the temperature changes. it will take m... | [
"Ice cream will have more thermal inertia, meaning that the full freezer will take longer to cool down to 0°, but will also take longer to heat up to ambient temperature if your freezer stops working. ",
">Does it take more energy to maintain temperature if the freezer is full of ice cream, or more if it's empty?... |
[
"Do balloons float or sink in vacuums?"
] | [
false
] | Would a balloon filled with, say, helium, float in a container that had been drained of air? Would it sink? | [
"It would either explode, or sink."
] | [
"People don't explode when they go into a vacuum though. They just kind of puff out a little bit and all the moisture on the skin starts evaporating."
] | [
"I agree with this. If you're doing this on earth in an imaginary vacuum chamber, then it would probably fall as there's no buoyant force that would direct the balloon upward. It would also depend on the strength of the material the balloon is made out of. As there's no external pressure that would normally be exer... |
[
"Why do our hands get sweaty when anticipating strenuous activity, and are often the first things to sweat? What kind of survival situation is benefited by slippery but slightly cooler hands?"
] | [
false
] | Is this just poor adaptation? In many sports - e.g. weightlifting, climbing - and work activities people need to chalk up their hands or wear tape or gloves for grip, purely to counter this crappy response from their body. I would imagine in a fight or flight situation, evolving humans needed grip much more than they n... | [
"In evolution terms, sweating has been around a lot longer than hairless bodies. So although it is complex and there is no definitive answer, you can't rule out the possibility that hand sweat under stress was a way to cool off as much as possible in anticipation of overheating from back when body sweat was not ve... | [
"And, as others have noted moisture generally improves grip of organic material (trees, rocks,)",
"The chalk bag of every rock climber out there would like a word with you."
] | [
"Something tells me our ancestors weren't scaling sheer rock faces for fun though."
] |
[
"How did earth initially develop an ozone layer?"
] | [
false
] | How did earth initially develop an ozone layer? | [
"UV light (and some atmospheric electricity like lightning) react O2 into O3"
] | [
"Hmm... This isn't meant as an answer, but O2 was produced after photosynthesis evolved. In fact, cyanobacteria and other oxygen producing organisms were responsible for a great number of extinctions due to the change in the composition of the atmosphere. The point is though, the oxygen was a result of photosynthes... | [
"okay, do we have any theories as to where the oxygen came from for the O2?"
] |
[
"What physically causes a feeling of anxiety or nervousness? Is there anything physical, or is it all in my head?"
] | [
false
] | For example I'm pretty anxious right now and I feel something weird right under my ribcage, my hands are shaking, and I can't slow down to focus or think straight. I'm more interested to know if something is physically happening under my ribcage right now that makes it feel like this, but an explanation for the other p... | [
"It's all in your brain...but your brain can make your body do many things that ARE real, such as tighten your muscles and raise your blood pressure/heart rate, pump out adrenaline and activate sweat glands (it can even trigger fight or flight mode) which are all real symptoms of your anxiety/panic disorder. The ki... | [
"It can definitely go the other way, as well. For example, if your adrenal glands aren't functioning properly, and dumping excess adrenaline or coritsol into you're blood stream, you're going to feel it, "
] | [
"The fact that this is a common question reveals a basic misunderstanding that most people have about biology and neuroscience. The mind is not separate from the body. The mind is part of the body. Anytime your body experiences changes due to external stimuli it is because your brain sent signals causing your body ... |
[
"Computer controlled electric motor."
] | [
false
] | Something I've been thinking about lately. I do not have a clue how to approach this so I thought I would ask. I do a lot of amateur astronomy. Unfortunitly, it is winter and therefore cold. I do not like the cold. I decided it would be neat, if I could arrange my telescope so that I could control it from my deskto... | [
"http://substack.net/posts/87bfa7/Robot-Telescope"
] | [
"Read up on stepper motors, as one of those would be perfect for this scenario. Basic gist is that they are \"digital\" motors, in that you send a signal to the motor to move a single step. Send lots of signals, and the motor starts turning.",
"The alternative is what's called a servomotor, which typically invo... | [
"You could always part out a cheap RC Car and use the radio to control the telescope for pretty cheap."
] |
[
"If evolution has emotionally rewarded beneficial actions, such as sex feeling good, why do I hate exercising?"
] | [
false
] | null | [
"You should keep in mind that our modern society is not at all a reflection of how humans have lived for the majority of our history. "
] | [
"Also to add, the adrenaline rush that accompanies things like being on a chase of an animal, or conversely running for your life, is not present when you are simply exercising. "
] | [
"Also to add, the adrenaline rush that accompanies things like being on a chase of an animal, or conversely running for your life, is not present when you are simply exercising. "
] |
[
"Where does the world's water go?"
] | [
false
] | I watched a documentary recently about how important of an issue water shortages are becoming. Even if water evaporates from one area, won't it condense in another as long as it doesn't get locked up in glaciers (which is becoming less of an issue with global warming, I'm guessing?) Help my feeble mind understand where... | [
"Humans use huge amounts of fresh water. When it leaves our houses it is grey water, which tends to get cleaned in a processing plant, sent into a river, and lost to the sea, where it gets mixed with saline water.",
"Our fresh water supply, therefore depends on two things; catching new fresh water from rainfall ... | [
"Spaceman Pete did skip over the fact that a lot of rain (freshwater) originates over oceans so while we can use desalinization natural cycles kinda take care of that for us. ",
"However, the real reason for shortages is that each person requires a certain amount of fresh water per day just to live and the more ... | [
"Outstanding answer! Thank you."
] |
[
"How will we venture to the Moon, to Mars and other planets when we will run out of fossil fuels?"
] | [
false
] | null | [
"Fossil fuels are only used indirectly in the current space programs. Most rockets are propelled by combining liquid oxygen with liquid hydrogen, neither of which are fossil fuels. ",
"However, to actually extract these gases and cool them to cryogenic temperatures, fossil fuel is currently being used. Ultimately... | [
"Unfortunately, it's quite likely that the Alcubierre drive is impossible to build. Essentially, he showed that there is a solution to General Relativity that allows a \"bubble\" to travel faster than light. However, it looks like it breaks our rules on energy, and it may be impossible to actually start it, steer i... | [
"Rocket fuel is mixing hydrogen and oxygen to make water. No fossil fuels required."
] |
[
"Is there a limit on how much energy superconductors can transmit?"
] | [
false
] | [deleted] | [
"Yes, superconductors have a critical current density above which they do not superconduct. The simplest way to think of this is that the current produces a magnetic field, and a strong enough magnetic field shuts down superconductivity, so eventually the current will be strong enough to kill itself.",
"You can f... | [
"The is a current density in a superconductor that cannot be exceeded without it losing it's superconducting properties. The current passing through the superconductor generates a magnetic field, but superconductors expel magnetic fields, so you end up with a very strong magnetic field surrounding the superconducto... | [
"So if the superconductors is made thicker that should lower the gradient of the magnetic field. Would that raise the threshold of permissible current density? Also what if the superconductor's geometry is that of a thin walled pipe. With sufficiently large OD could we get away with small overall mass (per unit of ... |
[
"What gives neural networks an advantage over other machine learning solutions?"
] | [
false
] | null | [
"A couple of different things.",
"For example, you might want to look at images and figure out whether or not they contain dogs. You can do this by writing a function f(x1,x2,x3...xn) where the variables xi are the pixels in an image, which will return 1 if there's a dog, and 0 if there isn't. Even if you can fin... | [
"/u/scienceistoohard",
" is describing CNNs or convolutional neural networks here which are important in image recognition and I think one of the easiest ways for laymen to understand neural nets. You can also do much cooler things like Generative Adversarial Neural Networks. ",
"In general, Machine Learning is... | [
"Neural networks are very powerful in that they can learn arbitrarily complex functions. When training a neural network, you don't need to have any idea what kind of function you're trying to approximate to represent your data. You just let the Neural network do all that work for you during learning.",
"The cavea... |
[
"What are the reasons for variations of Sr isotopes in the earth's crust?"
] | [
false
] | What causes variations is Sr86/Sr87 compositions in the Earth's crust? Also, why are their values higher in lavas on oceanic islands? | [
"While Sr 86 and 87 both obviously behave the same chemically, there are two effects. One is a tiny mass fractionating effect due to Sr 87 being slightly heavier. By far the most important effect, however, is that Sr 87 is a decay product of Rb 87. Rb behaves in a chemically different way to Sr, and therefore gets ... | [
"The values do not have to be higher on oceanic islands. As OrbitalPete mentioned, preferential partitioning of Rb leads to high time-integrated Sr87/Sr86 values. The high Sr87/Sr86 values of some islands can be produced by assimilation/mixing, assimilation fractional crystallization, and/or just tapping a source... | [
"Just to point out, Rb-87 has a 48 billion year half-life, so about 6.3% of the Rb-87 the Earth started with has decayed to Sr-87."
] |
[
"When viruses infect us and inject their DNA into our cells, does that (eventually) alter our genome?"
] | [
false
] | [deleted] | [
"Great question! I can’t see the other comments, so I’ll answer your question from scratch. ",
"TL;DR YES! And it’s happened A LOT",
"In answer to your first and second questions, viral genetic material (DNA or RNA) will only persist in you if it is integrated into your genome. Not all viruses do this though. S... | [
"To add to that we actuall have direct proof of a common ancestor with great apes because humans and chimps have the same string of viral DNA in our gene codes so it infected the reproductive cells of a common ancestor to both."
] | [
"A family of viruses that live in our bodies but doesn't alter our DNA are the human herpes viruses. There are 8 though we commonly experience of hear about 3 of them. When first infected, a viral particule hides away in the ganglion root of your central nervous system and remains there. This is why we continue to ... |
[
"What evidence is there linking violent video games to violent acts in real life?"
] | [
false
] | [deleted] | [
"While I am not a psychologist, this has been a topic of interest to me so I have read a number of papers on the subject. From what I've seen, these are the arguments of the side that believes video games cause real world violence: (sorry that many papers are behind paywalls)",
"fMRI",
" studies ",
"confirm",... | [
"Are there any studies that explore the opposite view - that playing violent video games can be an outlet that prevents actual real-world violence because the emotion could be lived out in a safe environment?",
"I think as long as such studies have not yet been conducted, any attempt at prohibiting such games wou... | [
"Unfortunately not. Most studies on the positive effects of video games focus on using them in an educational context."
] |
[
"What exactly is happening when vision deteriorates over time?"
] | [
false
] | null | [
"As people age, they tend to need glasses. Why is that?"
] | [
"As people age, they tend to need glasses. Why is that?"
] | [
"That tends to be presbyopia (\"loss of accommodation\"), the inability of the ciliary muscles to \"squish\" the lens of the eye to accommodate for close objects. ",
"Follow your finger and focus on it as it approaches your face. At a certain point, your eye cannot hold focus and it becomes blurry. Over time, thi... |
[
"If every light on earth shut off, what would we see in the sky? (At night)"
] | [
false
] | null | [
"Yes you would see bunch of stars and the milky way. You can do this by going camping."
] | [
"However isn't there still light pollution when camping? And would you see crazy purples and greens in the sky or is that just fantasy?"
] | [
"You can find plenty of examples of what the night sky looks like with minimal light pollution with a simple Google search. Re colors: are you talking about an aurora?"
] |
[
"Do virtual particle pairs in space make gamma rays in their cancelling?"
] | [
false
] | From my understanding, virtual particles are matter and antimatter particles that come into existence for a short while before cancelling out. I also heard though, that when matter and antimatter collide, they release gamma rays in energy, would that not imply that gamma rays are forming all over space? (that sounds co... | [
"Virtual particles are not real (hence the name \"virtual\"). They are names given to terms in a very large integral used to approximate the calculation of particle interaction probabilities. This is a common confusion and there are many threads discussing it if you search for them."
] | [
"When/if people say that they are describing a misleading heuristic. High powered lasers interacting with a particle can create particles. The calculation of that process involves an integral where you sum over \"virtual particle\" terms. But these are just mathematical expressions in an integral, and they are summ... | [
"Oh..what about when people say that they can make these virtual particles real? There were some posts saying that high powered lasers could separate the particles before they annihilate."
] |
[
"What is happening in my brain when I get light headed from standing up?"
] | [
false
] | null | [
"This is a common question. Try searching for something like \"stand up\". Unfortunately, because of the high volume, a lot of great questions and answers can get buried quite quickly. The searchbar can be a great way of exploring ",
"/r/askscience",
" and we encourage everyone to use it before posting."
] | [
"Thank you. Sorry for wasting your time I'll delete this post. And thank you for being a fantastic mod! I love this sub it always has good content!"
] | [
"No worries! Cheers!"
] |
[
"Which is more important to oral hygiene, the toothbrush or the toothpaste?"
] | [
false
] | Just curious, if you had to pick just one to use, which gives the greater benefit to maintaining oral heath? | [
"The toothbrush. While toothpaste assists in the removal of detritus (it's basically mouth soap) and helps strengthen teeth with its fluoride content, it's the toothbrush that removes food particles and plaque responsible for turning all the sugar in your mouth to lactic acid that wears at your teeth.",
"As mfigu... | [
"You could use it but I don't suppose that it would be more effective. Toothpaste also has abrasives in it like salt and talc that assist in cleaning. ",
"Soap also tastes very ungood. I don't think you're supposed to put it in your mouth, no matter what your grandmother has been saying."
] | [
"Since you seem knowledgeable on this subject: Would using soap, despite it being disgusting in the mouth, be more effective in oral hygiene than toothpaste?"
] |
[
"What is happening with large hadron collider?"
] | [
false
] | null | [
"The Higgs is confirmed, and the LHC is still running."
] | [
"They are still running proton-proton collisions, and lead-lead collisions. They're looking for signs of interesting physics in the first case, and studying quark-gluon plasmas in the second."
] | [
"They are still running proton-proton collisions, and lead-lead collisions. They're looking for signs of interesting physics in the first case, and studying quark-gluon plasmas in the second."
] |
[
"Is the Higgs Boson the only scalar boson that exists, or is there a possibility of another?"
] | [
false
] | null | [
"It’s the only elementary scalar particle in the Standard Model, but there are plenty of composite scalar particles. Any nucleus or atom with spin 0, for example."
] | [
"Gravity has a spin 2 Boson , not scalar though"
] | [
"To add to ",
"/u/RobusEtCeleritas",
"' answer, it is the only scalar boson in the Standard Model of Particle Physics, but there's plenty of stuff out there that isn't part of that model, e.g. gravity. I don't remember my particle physics and QFT lectures very well, but I'm sure many different extensions of the... |
[
"Does your car need to \"warm-up\" before driving it?"
] | [
false
] | null | [
"With any reasonably modern car (basically anything fuel injected), there really isn't a need to warm it up first. However, that is not a license to turn the key and floor it 5 seconds later. It is usually good practice to let it run for a short time (10-20 seconds) in order to let the cold oil fully start circul... | [
"Oh, and as to your bonus question about A/C, same thing applies. That was reasonable 20 years ago before cars were computer controlled - you would be starting the car and immediately putting a decent load on it from the A/C compressor charging up the unpressurized line. But these days the compressors are much mo... | [
"It's not the metal, it's the oil. Cold oil is thick and will not lubricate in the same way as warm oil. "
] |
[
"Are there methods or \"mind games\" a person can use to prevent going insane?"
] | [
false
] | A thought popped into my head about a movie I watched a few years ago. A man was locked up in isolation and, to prevent from going insane, did mathematics in his head for the duration of the imprisonment. Can you prevent from going insane in a situation like that if you kept your mind busy somehow? | [
"No. Human beings are social animals and require interaction to maintain their mental health (which is why solitary confinement qualifies as torture). There is the case of one man serving life in solitary confinement who created beautiful works of art by literally sucking the dye of M&Ms to use as paint. ",
"http... | [
"\"Anecdotal\" doesn't mean \"mythical\". If a single person spends a prolonged amount of amount of time in solitary confinement and is then found not to be insane by the best methods available, that is still anecdotal evidence. There would not be sufficient sample size or controls to make a statement about the sta... | [
"History is full of examples who chose volontary solitude without going mad in any meaningful sense. People from the Buddha through Anthony of Egypt to Emily Dickinson chose to spend parts of their lives in solitude, without going mad. ",
"Anecdotal historical \"examples\" (including mythical religious figures) i... |
[
"Why can carbon form four covalent bonds when the 2s orbital is paired up leaving only 2 solo electrons in the 2p Orbital?"
] | [
false
] | null | [
"The \"simple\" answer is molecular orbital theory. In methane, the 2s and 2p atomic orbitals in the carbon combine with the 4 1s atomic orbitals from the four hydrogen atoms to create 4 bonding molecular orbitals (and 4 anti-bonding molecular orbitals). The four electrons from the four hydrogen atoms, and the four... | [
"The other way to look at it is with hybridization (also known as the valence bond theory). The idea is that when atoms get involved in bonding, the outer shell orbitals combine into mixed or \"hybridised\" orbitals. So for example in a carbon atom, the s orbital could combine with the three p orbitals to make four... | [
"Thanks a lot! "
] |
[
"Before the Holocene were all humans hunter gatherers?"
] | [
false
] | If the Holocene is the current geological epoch which began 11,700 years ago and the development of agriculture and animal husbandry started around 10,000 years ago, does that mean humans were primarily hunter gathers before the Holocene? | [
"The shift towards agriculture and animal husbandry, also known as the Neolithic revolution, allowed for the development of larger, more complex societies and the rise of cities and civilizations. It also led to significant changes in human diet and lifestyle, as people began to rely more heavily on domestic crops ... | [
"Did the Neolithic revolution happen before 11700 bp anywhere?"
] | [
"Is it possible to ever know for certain that there weren't agricultural societies with simple degradable tools and buildings prior to the Neolithic revolution?"
] |
[
"When we say something is \"genetic\", how do we know it actually is biological and not a result of similar environments shared by parents and offspring?"
] | [
false
] | For example, depression is said to be genetic, but how can we be sure it is a result of inherited genes and not the fact that, say, a depressed parent will more likely raise a child in a similar environment that leads to depression? Not doubting research, just genuinely curious. | [
"Twin studies",
" are the classic way. Identical twins share almost all of their DNA, whereas fraternal twins and other siblings share 50%...so if something is more common in identical twins than non-identical twins, we can assume that it's more likely to be genetic. The other way is by finding actual genes.If yo... | [
"That's the difference between \"genetic\" and \"heritable\". It used to be super muddy back in the day before they determined that DNA was the physical material carrying genes - but after that, it became possible (although not easy until relatively recently) to determine exactly which genetic variants an individua... | [
"Depression is in a grey zone of likely being influenced by both genes and the environment. It's more like a genetic background might predispose you to depression.",
"Let's go for a more simple example, cystic fibrosis (CF). CF is definitely a genetic disorder. You can take any individual with CF, analyze their D... |
[
"Why does a container of liquid gas not cause the outside of the container cold?"
] | [
false
] | Should read "not cause the container to be cold" Silly perhaps but never found an answer. Eg. a canister of liquid nitrogen. Since the gas inside can not expand and is super cold when expelled why then does it not cool the metal container it is in. I'm going for perpetual refrigeration here but obviously there is a ... | [
"The gas only cools down when it expands. It remains at room temperature when in the liquid state."
] | [
"It’s liquid inside the container because it is below the evaporation temperature, and gas outside the container because the environment at atmospheric pressure is above the evaporation temperature. The container is heavily insulated, allowing very little heat transfer between the environment and the contents of th... | [
"Thanks I_Can't_logoff. That is true and I have now just looked up that fact. However can you explain why if something is submerged into say, liquid nitrogen it will freeze immediately in the liquid, i.e. the liquid is not at room temperature but at -321 F "
] |
[
"Is there a measurable difference, genetically or otherwise, between a heavy sleeper and a light sleeper?"
] | [
false
] | [deleted] | [
"There have been a few reliable differences found in \"light vs. heavy\" sleepers (aka, one's ability to maintain sleep in the presence of auditory stimuli), however the most interesting and promising is in a characteristic EEG finding known as a sleep spindle. ",
"Basically research consistently shows that peop... | [
"It's not actually a tangible \"thing\", but rather a specific pattern of measured brain activity characterized by 12-14 Hz waves that occur in bursts of about a half second."
] | [
"Sounds logical to me, however the contrasting argument might be that people who are sleep deprived (from frequent nighttime awakenings) might be more likely to fall prey during the daylight hours. Important to note that I am in no way an expert in evolutionary theory so my opinion on this side of the topic is ess... |
[
"Resistance to viruses"
] | [
false
] | When humans develope a resistance to a virus how long does it last. If we developed a resistance to flu, and the the flu was wiped out...but then reappeared 100 years later would people still carry the resistance? | [
"If you are talking about an individual developing resistance and then surviving those 100 years only to encounter the virus again, there is precedence for this. The recent 2009 swine flu virus actually shared some similarities with the 1918 flu virus. Studies of antibodies from a survivor of the 1918 pandemic sh... | [
"As has been pointed out elsewhere, there is a difference between resistance and immunity - so I hope that I was addressing what you meant by resistance. ",
"Immunity is another matter altogether."
] | [
"First, there are two parts of the immune system (in mammals and most vertebrates): the acquired and the innate immune systems. Acquired immune system is when you body learns to recognize a pathogen and in the future can effectively defend against future attacks. In theory this resistance lasts for a life time (wit... |
[
"What happens when a single photon is released and subsequently is absorbed?"
] | [
false
] | Lets say a single photon is released, perhaps it is the last one released from an object as it passes through an event horizon (this is what got me thinking about this). When I think about this photon as a particle, it seems like it will be released in a specific direction, and if something happens to be in that direct... | [
"That's why I put \"collapse\" in quotations. Whether it actually collapses or not is pretty irrelevant to your measurement outcomes or the predictions you make from the theory. If you were writing a theory describing the evolution of the photon, then initially it was a superposition throughout all space, and after... | [
"If it is a single photon, then only one observer can observe it. After the photon is admitted, assuming there are no constraints on its evolution, the photon's wavefunction (think of this as a probability wave) will spread out in all directions. However, once it is observed, the probability wave \"collapses\" to t... | [
"That's assuming that the probability wave actually collapses. That's just one theory (the Copenhagen interpretation); there are others, e.g. MWI, where such collapse is neither necessary nor actualised. So, one should be a little careful when making such statements as being a matter of fact."
] |
[
"What exactly is fractional distillation?"
] | [
false
] | Could someone please explain fractional distillation? I find it really confusing to understand. Thanks! | [
"Ordinary distillation is boiling a mixture to separate its components. You can do this in a flask or pot. If you get the temperature right, the component with the lower boiling point boils, and the other component stays a liquid. You can then collect the vapor and condense it to get the first component back.",
"... | [
"Yup, trust this guy to heat, pump, cool, condense and fractionate in a workmanlike manner."
] | [
"You need to read up on the concept of an \"azeotrope\". A mixture of water and ethanol boils to a vapor with 95% ethanol and 5% water. ",
"Many azeotropes exist. ",
"https://en.wikipedia.org/wiki/Azeotrope"
] |
[
"Why do we have cuticles?"
] | [
false
] | What is their purpose? And what causes them to become damaged so easily? Despite taking care of my nails, mine seem to break at the edges and become painful. | [
"Humans have cuticles to protect the nail bed from bacteria. If the nail bed were to continuously grow bacteria due to a lack of protection, the nail would not grow properly."
] | [
"The cuticle works to create a seal between the nail and the skin. You should be able to see why it would be an early mutation of land animals that practically every species would find beneficial.",
"Think about it. If you were an early land animal who had developed the mutation of claws and you did not have cu... | [
"Yes, and in early mammals cuticles very well could have meant life or death. But in current times, it just keeps bacteria from building up. Dying from lack of a cuticle today is unlikely, but you are correct. :)"
] |
[
"New material appears to convert heat to magnetic energy."
] | [
false
] | So a link to PopSci was posted to earlier, which was linking to . Skimming through (I'm a CETech major, not a physicist) it seems like it actually does convert thermal energy into magnetic energy, which is then harnessed as electricity. I was wondering if this is a clever way (phase transition) of going around the prob... | [
"The material only produces electricity once per heat cycle. So it's good for dynamic systems, where the heat is cycling a lot. This is in contrast to thermoelectrics, which produce electricity in steady-state with temperature differences.",
"As far as, \"is it better in situation X than technology Y?\" I'll have... | [
"Could the material potentially rotate through the heat? I.e. inside, then outside of a computer for the differences in heat."
] | [
"I suppose, but mechanically cycling things would likely be difficult and inefficient."
] |
[
"What is the evolutionary advantage of the poppy plant to produce morphine?"
] | [
false
] | null | [
"Alkaloids like morphine, nicotine, caffeine, and many more act as ",
"insecticides",
" for the plant in nature. Their effects on us are a bit of a natural accident."
] | [
"Exactly. It's interesting to realize that while we grow millions of acres of corn, wheat, and rice, to some degree we are serving the plants, rather than the other way around. "
] | [
"Their effects on us are a bit of a natural accident.",
"Which caused humans to cultivate the poppy, which is an evolutionary advantage."
] |
[
"How do electrons know they're being observed in quantum super position?"
] | [
false
] | [deleted] | [
"It's not that the electrons know anything. It's that the measurement requires an interaction with the electron, and it is this interaction that affects the outcome."
] | [
"I'll answer that with a qualified yes. The right way to think about this is that notions of wave and particle don't really apply; electrons (like everything else) are objects that follow the laws of quantum mechanics. There are situations in which those objects behave in a way quite like a classical wave, and si... | [
"I'll answer that with a qualified yes. The right way to think about this is that notions of wave and particle don't really apply; electrons (like everything else) are objects that follow the laws of quantum mechanics. There are situations in which those objects behave in a way quite like a classical wave, and si... |
[
"Is it possible to transmit composite/coaxial tv over fm radio?"
] | [
false
] | null | [
"That's almost exactly what broadcast television used to be, back in the analog days (i.e. before 2009 in the United States).",
"An analog broadcast TV channel consists of an RF carrier modulated with a standard NTSC composite video signal. The only difference is that instead of FM, it uses AM, or more accurately... | [
"If you mean FM broadcast band, then no it can't be done. FM channels are 0.2 MHz wide while analog video needs 4 MHz bandwidth. ",
"If you mean \"can analog video be sent using Frequency Modulation?\", then yes it has been done for over 60 years. It just needs more bandwidth than FM broadcast. We used to use 18... | [
"To add to what other people are saying, you can literally transmit anything you can transmit through a cable through the air as well. In practice, the coaxial cable is nothing more than trapping the same waves you'd send through the air inside a circular geometry so that it doesn't spread out and lose its power (t... |
[
"Why does egg turn white when you cook it?"
] | [
false
] | null | [
"Proteins are shaped with hydrophobic parts of the molecule on the inside and hydrophilic parts on the outside, allowing them to be water soluble. When the egg white is clear, you're seeing a solution with dissolved proteins in it.",
"Proteins are very large molecules that are typically designed to function in a ... | [
"Proteins are very large molecules that are typically designed to function in a certain range (of temperature, pH, ...). For most proteins, that range does not include typical cooking temperatures. On a molecular level, the heat imparted by cooking is enough to undo some of the bonds that give protein its structure... | [
"Disulfide bonds generally do not get broken by heat. ",
"They sort of don't fit into the usual categorization of protein structure that well; chemically they're more like the primary structure (peptide bonds forming each polypeptide chain), but they're holding together different parts of the chains and thus have... |
[
"What is the net charge of the universe?"
] | [
false
] | I don't mean a precise answer, but are there more protons than electrons in the universe? Or vice versa? Or do protons and electrons exist at (or extremely near) a 1:1 ratio, even if not equally distributed in terms of position relative to each other? From what I understand, a few fractions of second after the Big Bang... | [
"There are several indications that the universe is in fact charge-neutral. For starters, gravity seems to be the dominant force when dealing with cosmological length scales. Since the electromagnetic force is much much stronger than the gravitational force, if the universe had a net charge we'd probably see evid... | [
"You can have an infinite universe in which that's not true. ",
"1111111111111111111111111111111111111111.... is an infinite sequence of numbers, but there aren't any 2's. Not everything happens just because you have an infinity. "
] | [
"That's not at all obviously true if you allow the universe to be non-Euclidean. If the universe is a shaped in a way akin to the surface of a sphere (albeit in a higher number of dimensions), then there need not be a center. Where is the center of the earth's surface? Greenwich? The Pacific Ocean?",
"I don't kno... |
[
"If matter cannot be created or destroyed what happens when matter touches antimatter?"
] | [
false
] | null | [
"Matter ",
" be created and destroyed, annihilation is an example."
] | [
"I thought the workaround was gonna be something about not being actually destroyed in that scenario, somehow, I didn't expect that sentence to be false."
] | [
"It's a useful simplification in chemistry classes, but in high-energy physics processes, it's no longer true that matter can't be created and destroyed."
] |
[
"Do we know approximately how much neurons there are in the different parts of the brain?"
] | [
false
] | Or do we just know how many there are in total? For example, do we know how much neurons are used for language acquisition? | [
"We have rough, order-of-magnitude counts of the number of neurons in different regions of the brain's gross anatomy. However, this number keeps going up as we continue to study the brain. Just a few years ago, it looked like around 10 billion neurons in the cortex, and now it looks like the number is closer to 2... | [
"Great project! Some work has been done in this area that you might wish to learn about. One of the better understood systems is visual processing. In fact, there are people who are modeling visual systems using neural nets, and have also been setting up big parallel processing farms with GPUs to try and test var... | [
"I got the idea from Manfred Spitzer's book The Mind Within The Net. ",
"He writes about ",
"this paper",
". Rumelhart and McClelland model how a child acquires the past tense. Their neural network makes the same mistakes a child often makes, and it goes through the same learning phases. "
] |
[
"I'm eating a very old apple pie, which my wife is convinced would make her sick - are some people physiologically more tolerant to dodgy food, or are people just more/less risky with food intake?"
] | [
false
] | null | [
"Everyone's body will respond differently. Some people have food sensitivities that other's don't and different tolerances to fat's, spices, dairy etc. If you were both to eat something teeming with Salmonella you would both get sick, your immune system would determine how sick each of you got though. A lot of food... | [
"I frequently consider, as I throw away slightly wrinkled produce, that our ancestors would store barrels full of apples and citrus in their cellar or ship hold to help them survive a winter or voyage.",
"\nI'm sure the beasts at the bottom were not pretty, but we're here so most of them were also not deadly.",
... | [
"It depends on the type of bacteria or mold that colonizes the food in question. Some species of bacteria release toxins that can make you quite sick and it is independent of your immune reaction. Bacillus cereus, for example, releases a heat stable toxin that can make you sick even if the bacteria is not present. ... |
[
"Is the amount of energy in the universe a constant?"
] | [
false
] | So, there is this very common knowledge that you can't create or loose energy, it is just being converted from one form to another. So...since you can't make more of it or loose it by any means...then...does that mean that since the big bang and possibly before it...the amount of energy available in the universe as a f... | [
"Energy isn't conserved in the construct of general relativity (with exceptions of special cases). The statement made in an earlier comment is also incorrect \" As the universe expands the energy decreases\". That statement is valid for the redshifted photon only. By definition, redshifting implies lowering of ener... | [
"The redshifting does lower the energy content, but this does not imply that the universe as a whole loses energy - there are other processes going on other than redshifting photons.",
"\" As the universe expands the energy decreases\". That statement is valid for the redshifted photon only.",
"He is 100% agree... | [
"Energy conservation arises as a consequence of physical descriptions for systems being constant over time. In the same way as the conservation of momentum arises from the consequence of physical descriptions of systems being constant from place to place. On \"local\" scales, these descriptions do stay constant ove... |
[
"Why do people sweat when they are afraid?"
] | [
false
] | null | [
"Sympathetic nervous system.",
"I really need to get this added to the faqs.... unless it is already there.",
"Mods - can i volunteer to write a faq regarding the SNS? It would answer MANY questions, like this one.",
"I have only been here 5 or 6 months.... but this is the answer at least double digit times.... | [
"Never a curse. Knowledge is nothing but blessing."
] | [
"The thing is, I didn't find it here, nor I did find it after a superquick search in wikipedia. ",
"But if you would be kind enough to add it to the faqs, I would be happy to educate myself."
] |
[
"Why do I have three distinct hair colors if hair is controlled by two alleles?"
] | [
false
] | null | [
"hair colour is controlled by much more than a single gene with only two alleles."
] | [
"They didn't teach you ",
"Pleiotropy",
".",
";D"
] | [
"They didn't teach you ",
"Pleiotropy",
".",
";D"
] |
[
"If one were to mine the craters on the moon, would one find what made the impact?"
] | [
false
] | null | [
"You can sometimes find bits of meteorite in craters on Earth, but in impacts at orbital velocities, the impactors tend to vaporize and end up splattered over the landscape. For example, the impactor that made ",
"Meteor Crater",
" has left ",
"fragments",
", apparently constituting 15% of the mass, scatter... | [
"I think OP meant would you find the meteor that created the crater? Or would the meteor have bounced back into space after the impact?"
] | [
"Except that on the moon the impacts are at vastly higher speeds, not much left to find after that."
] |
[
"Single-celled?"
] | [
false
] | Is an egg a single-cell? If so, how is its structure similar to or different from body cells? | [
"The yolk is a single cell, but there is no nucleus yet. After fertilization the first three divisions are not even 'complete' so the the DNA is multiplied but the \"cells\" are still not completely separated by a membrane. "
] | [
"thanks."
] | [
"That's not true. The entire egg is a single (unfertilized) cell. The yolk is a nutrient mixture present for the developing embryo; it contains protein, fat, carbohydrates and cholesterol. Yolk is present in other animal oocytes as well, but it's not always in a big blob. Human eggs have the yolk dispersed througho... |
[
"Homeopathy is obviously a scam, but why is Chiropractic therapy also considered a scam? Other than they come from the same school of thought."
] | [
false
] | I have never understood why, since it does make my back feel better. My doctor even suggested it, but the general consensus I'm getting from my M.D bound friends is "You're retarded" without any reason given. Thanks! Edit: Alright, you know what? I decided to take advantage of my schools really cheap Physiotherapy inst... | [
"The reason that Chiropractic is sometimes rejected or ridiculed is that its origins are pretty well rooted in pseudoscience.",
"For example, some Chiropractors believe in the made up concept of \"vertebral subluxations\" (which they define a bit more broadly than \"subluxations\" in medical science) which subver... | [
"Just one note - makes sure that your chiropractic not only rejects the bullshit, but also has a solid training similar to that of a physiotherapists. Even if he doesn't believe in subluxations, he can still fuck you up badly (or at least not help you properly) if he doesn't know what he's doing."
] | [
"Several arguments against chiropractic therapy are described in Simon Singh's article ",
"Beware the Spinal Trap",
", for which he got unsuccessfully sued by the British Chiropractic Association.",
"I think there are five issues that get confused:",
"For treating back and neck problems, chiropractic appear... |
[
"How do we know of the existence of Dark Matter?"
] | [
false
] | [deleted] | [
"Copypasta of one of my posts from a while ago: To answer the question \"What makes scientists think that Dark Matter is the missing piece of the formula, and not that the formulas themselves are incorrect?\", I would say many converging lines of evidence, and a cosmological model that works extremely well. ",
"D... | [
"Most of the evidence for Dark Matter (as far as I know) comes from indirect observations regarding gravity.",
"True. We're hoping to find Dark Matter that interacts in other ways, but we haven't yet.",
"What makes scientists think that Dark Matter is the missing piece of the formula, and not that the formulas... | [
"I've always felt like we're compensating for evidence that doesn't add up with far-fetched explanations, almost like early astronomers did with epicycles in geocentric theory.",
"I can't address your other questions, but the situation now is that observation which doesn't fit our current theories, and one possib... |
[
"This has been bothering me. In January this year an Australian guy found a 5.5kg gold nugget. What caused all that gold to bunch up in one place?"
] | [
false
] | [deleted] | [
"The gist of it seems to be something called 'cold welding of smaller particles'",
"In your link, this mechanism is noted ",
" to occur..."
] | [
"I saw an article on Nature about the flash deposition of gold in faults:\n",
"http://www.nature.com/news/earthquakes-make-gold-veins-in-an-instant-1.12615",
"Perhaps, a geologist can comment on this?"
] | [
"Indeed, it's not really known how gold nuggets form (now that cold welding has been ruled out). It's only known that ",
"they form that way deep underground at high temperatures",
"."
] |
[
"How to use your brain efficiently?"
] | [
false
] | null | [
"These veers too close to medical advice against which we have strict guidelines. Try a different question or phrasing."
] | [
"Hmm, how would you recommend phrasing it?"
] | [
"I guess I'm not sure what it means to \"use a brain efficiently\". That's like asking \"how do you use your skin (or any other organ) efficiently?\" it's not something you have control over. You could try something a bit more general like \"does diet affect cognitive function and, if so, how?\""
] |
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