title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Is it possible for a spatial body (e.g. planet, star) to have a perfectly smooth surface because of its gravitational pull?"
] | [
false
] | Or, Why is the Earth's gravitational pull too weak to prevent mountains? | [
"As I understand it it, not quite. If I recall correctly the largest ridges on a neutron star are approximately 5mm in height. Which is pretty damn small when you consider that these things are thousands of km in diameter. Comparatively smoother than a que ball."
] | [
"Neutron stars have a radius between 10-20km, not thousands of km. ",
"http://www.astro.umd.edu/~miller/poster1.html"
] | [
"Even the event horizon of a black hole, which is probably the smoothest object imaginable (probably because it's not an \"object\", but whatever), has distortions due to frame-dragging."
] |
[
"Why are Neanderthals considered a different species from humans if we could interbreed and produce fertile offspring?"
] | [
false
] | I've often heard the word species defined as the largest group of organisms that can interbreed and produce fertile offspring, if that is the case why do we consider Neanderthals a different species when many people today have Neanderthal ancestry? | [
"species are more about having a distinct gene pool with little or no outside interbreeding, and neanderthals had that for a long time and so developed a genetic distinction of their own, becoming a separate species.",
"basically they are a different species because they formed a isolated group that didn't interb... | [
"The thing is, there isn't one definition of \"species.\" The context in which you are using it is important. Consider asexually reproducing organisms like bacteria, how would one define species there if the case you used is the only one? ",
"/u/The_Countess",
" has the right of it here."
] | [
"For some of the reasons that ",
"/u/ouemt",
" and ",
"/u/The_Countess",
" outline, the actual difference between species and sub-species is pretty irrelevant from a modern biological standpoint. Taxonomy is a great subject and very useful, but doesn't have as much weight in modern thinking of ancestry, sha... |
[
"Is there an extreme point where the temperature decreases with pressure rather than increase (gas)?"
] | [
false
] | So, there's this: pV = nRT . From this is clear that if volume and number of molecules are constant, if we increase pressure the temperature has to increase. Is there a point when, if we increase the pressure to an immense threshold that there is actually a temperature drop because the molecules cannot almost move anym... | [
"You have right intuition, but, as others have said already, it won't work like that for a classical gas.",
"See about ",
"negative temperature",
",\nif you have not a gas but a system of a kind with limited high energy states, by pumping enough energy into the system you could increase temperature from posit... | [
"confining a particle, doesn't reduce its kinetic energy. If you confine the particle enough, its mean squared momentum (and hence mean kinetic energy) would increase with proportion to how small the confinement is. ",
"That's the result of the momentum being proportional to the inverse of the wavelength of the p... | [
"Negative temperature makes more sense if you think about 1/T (called thermodynamic beta) as the fundamental quantity instead of T (temperature). Then positive infinity is absolute cold, a point that can only be reached asymptotically. Small positive values are \"normal\" hot, and negative values are the weird \"ho... |
[
"How viable is replacing/upgrading human parts with engineered ones at our current level of technology?"
] | [
false
] | Everything from prosthetic limbs to electromagnet "sensors" in the fingers. Please let me know if I should clarify more. AskAcademia didn't know much about the research of such things, so I thought I'd ask here. | [
"http://www.bbc.co.uk/news/science-environment-13273348",
"That is a story of a man who suffered nerve damage in his arm and lost use of his hand. The arm and hand were structurally fine, but the nerve damage couldn't be repaired so he elected to have his useless hand amputated in exchange for a robotic one that... | [
"If we could viably replace parts, why wouldn't we be doing so?",
"Except for where medically necessary, people tend to take that attitude of \"if it ain't broken, don't fix it\"."
] | [
"Wow! The second video where he shows his hand rotate 360 degrees was crazy. "
] |
[
"If there was a hole in the perfect center of the earth (like ~7-8 ft diameter) and you were in it, how would gravity affect you?"
] | [
false
] | null | [
"You would be weightless."
] | [
"At the very center, you would not feel any force.",
"This is a consequence of ",
"Gauss's law",
", which tell us that inside a spherical object with a mass we don't feel the attraction from parts of the object that are farther away from the center than you, and since you're at the center you will not feel an... | [
"Inside a massive sphere the force depends linearly on the distance to the center.",
"Only if the sphere has a constant density. A reasonable approximation for the core of Earth, but not for Earth overall. If you would dig a tunnel through Earth the gravitational attraction would increase by a few percent until y... |
[
"Can a planet or moon move directly through a gas giant planet and survive?"
] | [
false
] | null | [
"I thought the laws of physics were universal (except in the neighborhood of a black hole or other singularities), and it would take a different universe to have different physics laws?",
"As for OPs question, we actually observed Schumacher-Levy crash on Jupiter in 1994. It definitely did not go through."
] | [
"I thought the laws of physics were universal (except in the neighborhood of a black hole or other singularities), and it would take a different universe to have different physics laws?",
"As for OPs question, we actually observed Schumacher-Levy crash on Jupiter in 1994. It definitely did not go through."
] | [
"Pass through, no. Successfully end up inside before being destroyed, maybe. I have not actually seen any literature on this but it may be possible for a moon to enter a puffy gas giant. ",
" ",
"Puffy gas giants, also known as super puffs, inflated hot jupiters, and various other names, have up to twice the ra... |
[
"Will sea level rise, and differences in where it occurs more greatly, have any effect on continental drift and plate tectonics due to shifting weight?"
] | [
false
] | null | [
"This makes sense intuitively but it's not quite right (or at least natural examples don't really bear this out). In general we expect that mountain ranges (and especially ones well described by a critical taper) will approach a steady-state where uplift balances erosion rates. So a sudden increase in precipitation... | [
"According to ",
"data from NOAA",
", yes, it does. Also, ",
"this",
"."
] | [
"There might be some planetary-scale impacts, but I'd look more into things like changes in erosion speed, which would have effects on the state of critical taper in active mountain ranges and interplate sismicity and sedimentary rates along convergent margins.",
"In other words: mountain chains erode faster from... |
[
"If something is lifted by a magnet and the magnet is moved away with the same velocity, will the object and magnet remain at a constant distance apart?"
] | [
false
] | [deleted] | [
"you'd have to move the magnet ever faster away: If they're moving at the same velocity, they're at rest (with respect to each other). If they're at rest, the object is attracted to the magnet and begins to accelerate toward it. Therefore the magnet must move more quickly away from the object. So unless you're plan... | [
"As for your proposed idea, you could think of it kind of like a necklace going around the moon with beads every so often. You could push on one bead, and it'd push on the other beads all the way around, and they'd travel around together, but you'd have to push just as hard on that first car as you'd have to push o... | [
"magnetic force inversely proportional to the distance between the magnet and object",
"It's proportional to the ",
" of the distance. In the scenario you describe the single carriage would then no longer be balanced by the attraction of the carriage behind it (which was now weaker) and it would snap forward. I... |
[
"How does the wind carry sound?"
] | [
false
] | null | [
"OP, do you mean how does sound propagate in air? Or how does wind affect sound propagation?",
"I'm going to go out on a limb and guess you mean the latter, in which case, a wind front traveling with a constant speed will just make the wave propagate at 343 m/s (speed of sound in still air) + speed of wind for a... | [
"shockwave",
"Shockwave has a specific meaning in acoustics. So, let's replace \"shockwave\" with \"pressure disturbance\".",
"Slightly more nitpicky (sorry!), I would also say that acoustic waves don't propagate from particle to particle, just because that makes it seem like it's a phenomenon that's primarily... | [
"shockwave",
"Shockwave has a specific meaning in acoustics. So, let's replace \"shockwave\" with \"pressure disturbance\".",
"Slightly more nitpicky (sorry!), I would also say that acoustic waves don't propagate from particle to particle, just because that makes it seem like it's a phenomenon that's primarily... |
[
"How come when we walk, our arms remain straight, remaining down. But when we run, we automatically bend our elbows?"
] | [
false
] | And why is bending the elbows 90 or so degree more comfortable than keeping them straight? | [
"When you walk or run your arms act as pendulums to counterbalance the movements in your torso as your legs propel you.",
"A pendulum naturally swings at a fixed speed determined by it's length. By shortening the length of your arms you enable the pendulum to swing faster to better match your stride."
] | [
"In order to correctly counterbalance the motion of your legs, the movement of your arms doesn't need to match your movement speed, it needs to match the timing of the events in your gait. When you are driving forward off of your back foot your front arm helps to carry momentum forward. When your arm reverses direc... | [
"What",
"Your arms aren't just swinging freely when you run, and you can run at different speeds without changing the angle of your elbow. If we're pulling guesses completely out of our asses, I'd say maybe walking your arm movement is somewhat incidental (where they probably do just swing freely), but when you'r... |
[
"Is it possible to genetically determine in young age if somebody is likely to become a criminal?"
] | [
false
] | [deleted] | [
"Lazy criminology student here.",
"There are two main criminal theories in the field of Criminology; Positivism and Classicism.\nAccording to Cesare Lombroso, an Italian positivist, you could differentiate a criminal to a regular civilian only by looking at his facial and body structure. Almost all of his finding... | [
"I wholeheartedly agree with this answer. But there was an interesting study published last year in the journal ",
" entitled ",
"Examining the genetic underpinnings to Moffitt's developmental taxonomy: a behavioral genetic analysis",
". In this the authors found 56-70% of factors leading to being classifie... | [
"If your definition of criminal is based on commission of crimes, then I would say it is vastly unlikely since almost everybody is a criminal whether they are aware of it or not., and those who are not criminals will mostly be so due to luck.",
"If you restrict the definition to those who knowingly break a law th... |
[
"is the energy that life uses different from other types of energy such as light or heat?"
] | [
false
] | null | [
"i'm not quite sure at what you're getting at, but the base of all life is light energy: light is turned into chemical energy through photosynthesis, the chemical energy then travels up the food chain to eventually reach us\nfor example: Phytoplankton (converts light to chemical energy) -> zooplankton -> small zoop... | [
"If you're thinking of a concept such as a \"life force\" or something similar, then that is absolute nonsense. Your body runs on chemical energy that is no different than the chemical energy in gasoline, for example."
] | [
"It should be noted that there are other forms of energy that life uses, like electrochemical gradients."
] |
[
"Does being in an extended coma have any impact on the way the body ages?"
] | [
false
] | If you were in a coma for ten years, do we have any way of knowing whether you would look relatively older, younger, or about the same as you would if you hadn't been in the coma? | [
"I treat comatose patients for a living.",
"The answer depends on the age at which one enters a coma.",
"When kids become comatose or vegetative, their bodies still grow, albeit at a reduced rate since it is hard to keep them fully nourished and they often have endocrine problems, depending on how they were inj... | [
"As far as looks go, that's an interesting question. I would imagine the average person would look slightly younger because there'd be no sun damage or smoking wrinkles. Also decreased facial expressions could play a role. The masseter might be smaller from no chewing which could attribute to the emaciated look; I'... | [
"So sad. A friend of mine who is a couple years younger (He's 18) had a traumatic brain injury one year ago and most of what you described has happened to him "
] |
[
"Why is belly fat different from other fat?"
] | [
true
] | [deleted] | [
"abdominal fat is more correlated with insulin resistance. We don't know if the belly fat causes insulin resistance or if insulin resistance makes you more likely to store belly fat. ",
"http://diabetes.diabetesjournals.org/content/45/5/633.short"
] | [
"There are studies linking stomach fat and health problems."
] | [
"Additionally, your body \"likes\" to store fat around the belly, buttocks, and hips. This is because your torso moves the least. Think about it - if all your belly fat was instead located in your fingertips, it would take a lot more energy to move your hand around with the extra weight on it, as your arms and legs... |
[
"In space could a planet orbiting a star orbit faster than another planet with a closer orbit to the same star?"
] | [
false
] | I'm currently replaying Mass Effect and clicking on planets in systems when something that caught my interest in the planetary details. I'm in a 6 planet system and the orbital periods for the planets are as such Planet 1: 0.1 Earth years Planet 2: 7.8 Earth years Planet 3: 20.4 Earth years Planet 4: 1.1 Earth years Pl... | [
"Probably a typo and it should be 31.1 years. The scenario as described is impossible."
] | [
"For circular orbits:",
"a - acceleration due to gravity",
"v - orbital speed",
"r - distance from center of gravitational body",
"t - orbital period",
"k - constant in gravitational equation, equal to the gravitational constant multiplied by the mass of the body.",
"a = v",
" / r, alternatively v = s... | [
"I agree that it is not possible, but circular orbits are kind of rare, especially as you get farther away from the parent star."
] |
[
"Do points on the equator always have 12 hours of sunlight and 12 hours of darkness?"
] | [
false
] | [deleted] | [
"A graphical answer.",
"Also just pretty interesting."
] | [
"The day is slightly longer than 12 hours at the equator because the sun is refracted through the atmosphere, causing it to appear higher in the sky than it would without an atmosphere. The other main reason the day is slightly longer than 12 hours at the equator is that we define a day as when the first part of th... | [
"Bonus fun fact:",
"The angle of refraction through the atmosphere is such so that the visible offset of the sun against the horizon is roughly the same as its diameter.",
"When you ",
" the sun just touching the horizon is about the moment it ",
" actually below the horizon."
] |
[
"Will using bigger, external antennas improve signal reception on smartphones?"
] | [
false
] | 15 years back, all cellphones used to have an extensible antenna you had to pull out whenever you wanted to speak. Then the Nokias started coming out which just had a "bud" antenna that extended an inch out of the phone. Then all phones started having internal antennas. My question is, have we sacrificed on the signal ... | [
"The size of the antenna is directly proportional to the wavelength it provides gain for. So it really depends on the wavelength/frequency you are trying to pick up. The higher the frequency, the smaller the antenna, in general. The right external antenna will certainly improve your signal strength.",
"cell phone... | [
"The internal ones are the hardest to design because of space constraints. External MIMO ones are more difficult to design than the old pull-out whips which OP mentioned. "
] | [
"All true. ",
"Also, we require our phones to operate in any position, on multiple bands, and resist multipath cancellation. A simple 1/4 wave whip with ground plane isn't enough anymore. ",
"MIMO",
" antennas are used which would be very difficult to reproduce externally without lots of simulation and testin... |
[
"If high temperature rock essentially condenses into glass, why is the surface of the earth made of rock not glass?"
] | [
false
] | null | [
"Igneous rocks are divided into two groups: volcanic (or extrusive) and plutonic (or intrusive). There are examples of rocks made of glass, e.g. obsidian. These are volcanic rocks that are formed when lava is quenched rapidly; in fact, too rapidly for crystals to form into an orderly lattice structure. But plutonic... | [
"Sand is (often) composed of quartz, which differs from glass and amorphous silica in having a definite crystal structure. In glass, the silicon and oxygen atoms are more or less randomly arranged."
] | [
"The overwhelming majority of rocks present at the surface were not formed there but at depth, either through metamorphism, intrusion or diagenesis and subsequently brought to the surface through tectonic processes and erosion. Those rocks are generally at desequilibrium relative to surface conditions.",
"The \"w... |
[
"What is the heaviest element that is safe to handle or carry around all of the time?"
] | [
false
] | I was watching videos and they mentioned that Osmium was the heaviest element. I looked it up and it seems that it wouldn't be safe to carry it around in your pocket. What is the heaviest element that a person could handle and carry around safely? | [
"As Fabien said, iridium is the heaviest thing you could carry around fairly safely. However, it's reasonably expensive and hard to find as jewelery (I extrapolated you asking about carrying around all the time to being a piece of jewelery). If you're after something you could get a ring or chain made of fairly eas... | [
"Where did you get those density values? Wikipedia and WolframAlpha both show 22.59 for Osmium and 22.56 for Iridium."
] | [
"Old textbook... It's one of my dad's, from the 70s, probably wrong. Will defer to your values"
] |
[
"Can electric propulsion be used to launch rockets into space?"
] | [
false
] | I've been looking at the differences between chemical engines and electric propulsion (EP) engines for rockets. Whilst the EP engines work well in space they don't seem to have enough thrust to launch a rocket into space and completely replace chemical engines. Does anyone know if this has been done or could possibly b... | [
"Not really! Not yet, at least.",
"The idea with EP engines or things like ion thrusters is that they give a small amount of thrust, but they do it very efficiently, so you can keep on thrusting for a very long time. If you're in space, this all adds up over time, and you can end up going very fast with very litt... | [
"I know. I personally hope it's greater than zero thrust. science paradigm shifts are exciting.",
"In my reply I wanted to emphasize the huge gap between what the drive might potentially generate and the force required to launch something from Earth."
] | [
"The EM drive that was tested by NASA has been reported to produce something in the order of micronewtons, so we need to improve it by a factor of billions before it could ever be used to launch something.",
"Assuming that number means anything. In that NASA paper, they didn't quantify any systematic errors. So t... |
[
"I picked up this lab apparatus at an estate sale, can anyone tell me what it's used for?"
] | [
false
] | null | [
"Looks like something used to purify water, but I could be wrong. If you can't get it spotless with acetone, strong acid, or other powerful cleaner, you won't be able to sell it. "
] | [
"looks like a soxhelet extractor"
] | [
"http://en.m.wikipedia.org/wiki/Soxhlet_extractor"
] |
[
"Are there tides underground?"
] | [
false
] | Do tides effect underground lakes or groundwater? What about magma chambers? | [
"Have a read of ",
"this report, especially the graphs on page 13 and 14",
". It shows how the tides ",
"affect",
" the water level underground. Essentially with underground wells and groundwater, the water level moves up and down in cycles in much the same way as other large bodies of water like the sea.",... | [
"With respect to tides caused by the Sun. Counterintuitively, even though the Sun's gravitational force on the Earth is closing in on 200 times that of the moon, the tides are nearly undetectable by comparison. This is because the tides are caused by a gravitational differential from near side to far side of the Ea... | [
"The ratio of the mean distance to the sun to the mean distance to the moon is about 390.",
"The ratio of the mass of the sun to the mass of the moon is 27 million.",
"Thus the ratio of the tidal forces (which is given by the ratio of the masses divided by the cube of the ratio of the distances) is about one ha... |
[
"Is it really bad for the body to eat Food with flavour enhancers like Monosodium Glutamate?"
] | [
false
] | null | [
"Monosodium glutamate (MSG)",
", is merely the monosodium (one Na+) salt of the amino acid, ",
"glutamic acid",
". Glutamic acid is one of the 20 amino acids that make-up all the proteins within your body, alongside being a key neurotransmitter (sending messages between neurons) in the nervous system. When MS... | [
"It's BS. Some people with glutamate sensitivities can get headaches from over-consumption of it, which may have contributed to people believing the ridiculous 'brain cell loss' talk."
] | [
"Exactly- MSG is a primary amino salt, and a direct trigger of the umami taste (savory) in your tastebuds. This is the same as NaCl with your \"salty\" taste trigger.",
"For this reason it gets loaded into junk food to render savory flavor.",
"It is in itself harmless, but gets applied poorly, thus the bad name... |
[
"Is there any scientific data to suggest barometric pressure can cause physical affects like headaches or increased arthritic pain?"
] | [
false
] | This is such an incredibly common and everyday accepted thought, at least in my part of north america. Are there any studies to back this up? I couldn't find much. | [
"http://www.ncbi.nlm.nih.gov/pubmed/21921370",
"CONCLUSION: Barometric pressure change can be one of the exacerbating factors of migraine headaches."
] | [
"Please everyone, do not post your anecdotal experience here. This is looking for a specific mechanism, not your personal experiences. Thanks. "
] | [
"Isn't that more to do with being on the safe side to avoid going into labour during the chaos/cleanup of the hurricane though?"
] |
[
"What is future of instruments that depend on superconducting magnets, given the possibility of a helium shortage in the future?"
] | [
false
] | null | [
"The notion of a helium shortage is very overblown.",
"Helium is a by product of natrual gas production. The US used to stockpile helium for Cold War purposes. They liquidated the stockpile, which lowered prices to the point it wasn't profitable to collect it anymore. ",
"So now the stockpile is liquidated, ... | [
"Helium isn't going away any time soon but it is getting more expensive.",
"People are simply going to want to switch to recycling helium (before they would liquefy it once then let it boil off to atmosphere). Once you set up a recycling system, one `charge' of helium ends up being a small part of the price."
] | [
"So then, with helium eventually going to be costly, what is the future of instruments that depend on superconducting magnets?"
] |
[
"Why are people predominantly right handed?"
] | [
false
] | null | [
"There are many theories, but the prevailing current research indicates that handedness, and specifically right-handedness, is a trait that can be attributed to tool use, and is likely inherited from a common ape ancestor. ",
"Several recent studies put forth the theory that the hand used to interact with the wor... | [
"But why right? Like why can't I just switch the words \"left\" and \"right\" in your answer."
] | [
"I'd like to see your sources for that left brain, right brain stuff."
] |
[
"Is taking rabies vaccine 100% effective? as in the once infected person won't need a booster shot in the future?"
] | [
false
] | Suppose a patient is given the treatment for rabies after getting bitten and then gets cured after a while. Are there any chances the infection might still stay active somewhere in the body for years? Are the booster doses needed? Is there any scenario where the cured person still has a possibility to get infected afte... | [
"You're supposed to get a titer every couple years to check your levels of protection and if those levels drop you would require a booster. I have friends that work with bats and other wildlife and haven't heard of them needing boosters over many years but I'm sure it happens."
] | [
"Typically every ",
"2yrs",
" for titers.",
"The only problem? No one knows what titers specifically are protective; the \"less than\" level requiring a booster is somewhat arbitrary. ",
"For obvious reasons, the experiments necessary to determine the appropriate level - exposing people with varying antibod... | [
"If you have a bite or a suspected bite, you get two things on the first day. You get your first dose of vaccine as well as a weight based Immunoglobulin (Ig). Vaccines take time to work, and so to keep you from death the Ig is basically premade antibodies that will work to fight rabies immediately. ",
"So Day 0 ... |
[
"This might be a stupid question. With rising sea levels, can't we just dig dirt from the ocean floor to make it \"deeper\"?"
] | [
false
] | They say over a long period of time coastal cities will disappear, but wouldn't taking dirt out of the bottom of the ocean allow it to hold more water? | [
"This is the type of question where simple, back of the envelope calculations can be useful. It is important to realize just how big ",
"ocean is",
", with a surface area ~361 million km",
". Even if we ignore the complication that at an average depth of ~3700 m (and many places significantly deeper), consist... | [
"Aside from the physics issues, there is so much life on the ocean floor that it would likely be ecologically disastrous. Many are endemic, undiscovered, endangered, or all of the above. ",
"There are also many other ecological problems caused by climate change in addition to rising sea levels, so addressing the ... | [
"It's almost liks you'd need to cause an entire global industry's worth of disruption to cover this single symptom of a certain globla industry's activities."
] |
[
"Have we found any ways to make a neural network or other ML algorithm tell us \"why\" it came up with its decision?"
] | [
false
] | I know that's a big issue with ML systems, that their algorithm is completely illegible by humans. It finds a pattern and produces an answer, but besides the neuron weights we don't know how it defines the pattern or produces the answer. Have we found any way of extracting a more human-legible reasoning system from tra... | [
"Not to be overly critical but most of what you said is not accurate. It's a little much to type out on my phone, but your first point about NNs lacking reasoning is spot on - the power of machine learning comes from learned relationships instead of designed heuristics.",
"However, it is unfair to say that networ... | [
"Not to be overly critical but most of what you said is not accurate. It's a little much to type out on my phone, but your first point about NNs lacking reasoning is spot on - the power of machine learning comes from learned relationships instead of designed heuristics.",
"However, it is unfair to say that networ... | [
"I didn't really mean to say they're black boxes. My point was that after we structure the network and determine how it's trained, there's no longer abstract intention that goes into it, and therefore its behavior is blind.",
"We can determine what relationships it's focusing on through analysis, and we can even ... |
[
"Would this be an hypothetical action/example considered “faster than light”?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"You question is either commonly occurring or has been recently posted on ",
"/r/AskScience",
". It may also be answerable using a Google or Wikipedia search.",
"To check for previous similar posts... | [
"hey there!",
"Please cite where this has been asked before."
] | [
"You can find answers in our ",
"physics FAQ",
". In particular ",
"this link."
] |
[
"What are the biggest problmes people would enconter living in Mars 3.6 m/s² gravity?"
] | [
false
] | null | [
"We don't know for certain.",
"What we do know is that living in microgravity affects the immune system, and it causes bone mass and muscle mass loss. This is under active reasearch, especially in the ISS.",
"http://www.nasa.gov/content/study-reveals-immune-system-is-dazed-and-confused-during-spaceflight/",
"... | [
"well 50kg on earth would be a lot heavier then 50kg on mars because of the 1/3 gravity, so what im wondering is would the muscle mass loss cancel out the fact that everything would weigh less? yes, you would loose muscle mass, but at the same time everything would weigh less. i am genuinely curious, so if someone ... | [
"well 50kg on earth would be a lot heavier then 50kg on mars because of the 1/3 gravity, so what im wondering is would the muscle mass loss cancel out the fact that everything would weigh less? yes, you would loose muscle mass, but at the same time everything would weigh less. i am genuinely curious, so if someone ... |
[
"Do we naturally think in Base 10 (with 10 numbers!) or is it a cultural influence?"
] | [
false
] | null | [
"Other cultures have had different number systems. ",
"The Babylonians had a base-60 system",
", for example.",
"Also, the Roman system didn't have zero, so it didn't have a base per se. Just symbols for different values. It made arithmetic very hard. The number system we use now is ",
"the Arabic system",
... | [
"It's ",
" \"natural\" or \"the most natural\", though. There are plenty of other body counting systems. ",
"Some cultures touch each joint of the fingers with the thumb, letting you count up to 12 on one hand.",
"The ",
"Foe count not just the fingers, but all the way up to the top of the head and then bac... | [
"I believe it's been demonstrated (through interactions with modern pre-mathematics societies) that humans naturally think in a logarithmic base, and can only naturally (\"instinctually\") identify rough halfs/doubles of given values.",
"I'll try to find a citation.",
"As for your other questions, plenty of adv... |
[
"Is the lack of hair on our bodies for the purpose of keeping us warm a way we physically adapted to our technology i.e. clothes?"
] | [
false
] | null | [
"No. ",
"source"
] | [
"From the article:",
"Loss of fur was an adaptation to changing environmental conditions that forced our ancestors to travel longer distances for food and water.",
"Analyses of fossils and genes hint at when this transformation occurred.",
"The evolution of hairlessness helped to set the stage for the emergen... | [
"Ah, the famous Clinging Garbage Theory. Sounds like solid science to me."
] |
[
"What is the physiological mechanism through which fatigue/tiredness can cause visual/auditory anomalies?"
] | [
false
] | I'm a very fatigued medical student studying not-neuro right now, but I always notice these little visual anomalies when I am very tired. Like when I stare at words on a computer screen, they will start to ripple, or I'll see color start to materialize on a white screen. (I know I need sleep, thank you) I'm curious how... | [
"Not sure if this is what you are talking about, but sleep deprivation means your brain doesn't get a chance to \"flush\" itself properly.",
"When you're asleep your brain makes itself allow the brain fluid to wash over and into the whole brain, and pushes it back out to the outside of the brain. It does this man... | [
"Think of it like this: When you drink alcohol or take some type of medication (cough syrup, benadryl, whatever it is), your brain is affected because the neurons can't propagate signals properly, causing you to make mistakes about what things are and such (which is why it says \"don't operate heavy machinery until... | [
"Why does this seem to have similar effects to stimulant psychosis (before lack of sleep even hits), alcohol withdrawal, or plain psychosis in general? You could also throw benedryl or other anticholinergics in there too. I’m talking visually speaking"
] |
[
"How do engineers plan for thermal expansion when laying traintracks in deserts where the daytime and nighttime temperatures are vastly different?"
] | [
false
] | null | [
"Railway engineer here.",
"There's some misinformation in this thread but most people have the gist of it.",
"Most modern lines will use lengths of continuously welded rail (CWR), where you can have miles of rail before there is any physical gap. This length of rail would normally be subject to large amounts of... | [
"Depending on the location and age of the railway technology, they leave small gaps in the track (really!).",
"https://en.wikipedia.org/wiki/Track_(rail_transport)#Joining_rails",
"Generally, these are being phased out but this technology has served the railways in India for over a century (in a climate where t... | [
"Engineer here",
"We use expansion joints, similar to this one: ",
"https://en.wikipedia.org/wiki/Expansion_joint#/media/File:Expansion_joint,_Hayle.jpg",
"That will allow the metal to expand and shrink depending on the temperature",
"There is expansion joints all around you guys, there are most of time unn... |
[
"Before the big bang?"
] | [
false
] | [deleted] | [
"The comment by Gustomucho is fairly similar to my best understanding. The article he posted was new to me and very insightful.",
"I would like to say that the idea of the \"big crunch\" is kind of dismissed, at least in its original form. The idea was that gravity would eventually bring the universe back togethe... | [
"'We' do not really believe that the universe will have a big crunch. It all depends on the ",
"matter (Ω_M) and the dark energy density (Ω_Λ)",
" of the universe. A high mass density would lead to a big crunch, since the gravitational pull will overcome the expansion, however expanding the universe indefinitel... | [
"Wait, here is a Wikipedia article about the ",
"Big Bounce",
". It seems to have a bit more of a complete explanation than I do, and it seems to be a little more up to date than my understanding."
] |
[
"Is it possible to identify the food someone ate through their stool?"
] | [
false
] | null | [
"Absolutely! In fact, that's a significant component of anthropology and paleontology. Through examining coprolites (fossilized dung), scientists can obtain information about what the poop producer (human or animal) was eating, and build a better picture of their diet and the environment and society they lived in... | [
"i expected this answer because usually i can identify what i ate just by looking at my stool. "
] | [
"It gets even more interesting when in certain circumstances we can identify the food that someone's food ate prior to being eaten! Then we get to check out how much of the prey's internal microbiology has in common with the predators that consumed it!"
] |
[
"How does a musician tell whether a note is in tune, especially when it is being sung or played with vibrato?"
] | [
false
] | [deleted] | [
"The pitch of a note is the frequency which the instrument vibrates the air at. Our ears can naturally tell the difference between two pitches, but sometimes it takes some training to distinguish them. There are 12 standardized pitches in western music, all in half step intervals. Every other pitch is just a multip... | [
"Anyone, even non musicians can identify intervals, even if you might not know them by name. For example, take Twinkle Twinkle Little Star. The first two notes are the same, but the jump to the next note is a perfect fifth. Sing it in your head, you should know what it sounds like. If that's exactly what you hear o... | [
"To add to this, why can some people tell very naturally that two sounds are in tune with each other, and other people be completely \"tone deaf\"?"
] |
[
"Why do I get freckles and does my hair go blonder when I get a lot of sun?"
] | [
false
] | null | [
"I'm not sure on the freckles, but I can tell you that hair getting lighter from exposure to sun is due to a phenomenon called photobleaching- essentially, the light is providing the energy necessary for pigment molecules in your hair to break down into smaller products with less conjugation that don't absorb the s... | [
"its your genes \nFreckles are spots usually seen on people with fair or light skin. These spots contain melanin, a pigment protein.",
"Melanin gets made when harmful ultraviolet (UV) light from the sun hits our skin. This UV light is very powerful and can damage DNA. Melanin shades and protects our DNA from the ... | [
"From what I understand, your skin is able to make \"fresh\" melanin, while the melanin in your hair is already there and can't increase due to your hair being dead except for the roots under the skin."
] |
[
"Why is IV tPA for stroke patients have to be administered (generally) in under 3 hours? Why wouldn't it be as beneficial afterwards?"
] | [
false
] | [deleted] | [
"The longer the tissue has been without blood flow, the lower the chance it will recover when flow is restored. Longer time also decreases the amount of recovery that can happen. ",
"The time frame for tPA is a risk/benefit balance. The window closes when the chance of meaningful recovery drops below the chance o... | [
"This sounds like a homework question.",
"But anyway, the answer is because after several hours, all the ischemic tissue is dead, and hence restoring blood flow will do nothing but increase the risk of hemorrhage."
] | [
"Yes, this is correct. tPA increases blood flow to ischemic regions, and can make hemorrhagic regions worse. The first step, really, is to ascertain if the stroke is ischemic or hemorrhagic. Then, if it is ischemic, and you are within time limits, you give the tPA. Neurological clinics have set up telemedicine link... |
[
"With a strong enough magnet, is it possible for the human body to be affected/harmed by a magnetic field?"
] | [
false
] | I know that there is a lot of iron in the blood, and we have quite a few different metals in our body (in tiny amounts).... what would happen to us if we were placed under the influence of an powerful magnet? Would we be harmed in any way? | [
"Here is a video of a frog levitating over a magnet",
"https://www.youtube.com/watch?v=A1vyB-O5i6E",
"A strong enough magnetic field would be able to get the atoms in your body to line up and become magnetic. The frog is unharmed, but I certainly wouldn't want to have any metal fillings if this were being perf... | [
"Magnets occur because of spinning electrons.",
"No.",
"Electrons are point-particles. They do not \"spin\". We ",
" it \"spin\" because a stationary electron with some non-zero size that is spinning would produce a magnetic field, yes. However, we are talking about quantum mechanical spin here. There is only... | [
"So what is actually going on in that video, scientifically? I can't imagine how something like this would not be painful.... I could be looking at it all wrong though."
] |
[
"Do shock waves always travel at the same speed?"
] | [
false
] | [deleted] | [
"They travel at the speed of sound",
"Uhh, no. Acoustic/sound waves travel at the speed of sound. Shock waves are not sound waves, and travel faster than sound depending on the pressure driving them. They only travel at the speed of sound in the limit of an infinitely weak shock."
] | [
"They travel at the speed of sound",
"Uhh, no. Acoustic/sound waves travel at the speed of sound. Shock waves are not sound waves, and travel faster than sound depending on the pressure driving them. They only travel at the speed of sound in the limit of an infinitely weak shock."
] | [
"The speed of sound of an ideal gas is a function of temperature, not of pressure. If you've got air at 1 atm at room temperature and you have air at 0.01 atm at room temperature, the speed of sound is the same in both samples. This is because ρ (density) and K (bulk modulus) are the two properties which determine... |
[
"Why are fluids (and/or fluid dynamics) so hard to model?"
] | [
false
] | [deleted] | [
"The equations that describe them",
" are known, but \" theoretical understanding of the solutions to these equations is incomplete. In particular, solutions of the Navier–Stokes equations often include turbulence, which remains one of the greatest unsolved problems in physics, despite its immense importance in s... | [
"Fluid mechanics isn't ",
" bad until you get to turbulence. Turbulence is a mathematical nightmare."
] | [
"Even after making some simplifying assumptions for specific cases, what you usually wind up with are a set of coupled non-linear partial differential equations. To generate a solution for a specific set of initial conditions is impossible analytically, unless you manage to guess, because the non-linearity makes i... |
[
"In the history of life, was there any evolution in single celled organisms during the two billion years between the formation of prokaryotes and complex single-cell life?"
] | [
false
] | If so, what happened during this period? | [
"A big change was the evolution of photosynthesis. Cyanobacteria evolved to perform photosynthesis, which led to tons of oxygen eventually filling up the atmosphere, which lead to toxic oxygen by products being formed, which led to other bacteria evolving enzymes which could destroy those toxic oxygen by products."... | [
"Not sure what you're asking here. Evolution doesn't stop. It's a dynamic process."
] | [
"I guess I wanted to know of the changes that happened during this time."
] |
[
"Can the gravity and elemental composition of the celestial bodies in our solar system have an affect on humans."
] | [
false
] | Was wondering if there is any scientific evidence that celestial bodies in our solar system play a part in human behaviour. Or if they can have an affect of the physiology of the body. Besides the obvious affect the sun and the orbit of the moon plays (night and day, energy). For example is the pull of the moon able to... | [
"As far as gravity is concerned, the answer is almost certainly not (at least to any appreciable degree). Consider the following:",
"The gravitational attraction between two things can be calculated using the following ",
"formula",
":",
"force = G * m_1 * m_2 / r^2\n",
"Where:",
"G is the ",
"gravit... | [
"Exactly, the doctor that helped deliver you as a baby exerted more gravity on you than Jupiter at that time."
] | [
"Probably your hat has a stronger gravitational attraction force than any of the celest bodies, except the Moon."
] |
[
"Can I reproduce the sound on one record by exactly duplicating the grooves on a blank record?"
] | [
false
] | I know that records are played by placing a stylus in the grooves of a turning record. My question is, could someone take a blank record and scratch the exact same grooves into it as an Eric Clapton record, play it, and have it sound just like Eric Clapton and the rest of the band? | [
"Yes. That is how they make the record in the first place, from a master copy."
] | [
"yes there are programs that can kinda play vinyl by a normal PC scanner.",
"also, laser vinyl players are toys of the audiophiles",
"http://en.publicdomainproject.org/index.php/Laser_turntable"
] | [
"Secondary question -- Could one play a record without touching it? By perhaps magnifying the grooves and using a computer program to predict what the sound would sound like?"
] |
[
"What shape is my vision"
] | [
false
] | null | [
"It's circular - kinda. More precisely, the distribution of receptors in the eye is radially symmetric (save the blind spot, where the nerves connect). At the center of your field of vision, cones provide high quality, color vision. In a ring around that, rods provide fast monochromatic vision (to catch a predic... | [
"Incidentally, astronomers practice that looking-without-looking trick specifically because of the better light sensitivity where you're not looking. So if you're trying to see something faint, looking near it but not at it works better."
] | [
"We don't see a clearly-defined field like a TV screen displays - we don't really see much at all at the edge of our vision - but the field that we see through each eye is approximately circular:\n",
"http://www.ncbi.nlm.nih.gov/books/NBK220/",
"Light passes into the eye through the pupil (which is circular) an... |
[
"What is the science behind the possibility of immortality? Would 'nanorobots' be necessary or could we potentially live forever by reprogramming cell death and repair in our bodies?"
] | [
false
] | [deleted] | [
"Well right off the top of my head, I'd say until we figure out how to stop cancer, immortality ain't happening. From what I understand (the bio guys correct me if I'm wrong), like any system, as your cells replicate, there's a very small chance that your DNA gets copied over incorrectly. Over time, these errors bu... | [
"I think a major issue would be DNA replication. ",
"Telomeres",
" aren't regenerated when DNA is reproduced, I am probably going to butcher the description but when DNA is replicated the DNA polymerase can't start a strand from scratch so it starts just before the end (at least in one direction, I'm not even ... | [
"Which is why the nanobots would be programmed to detect cancerous cells and destroy them! Just poke a hole in the membrane and let it deflate like a water balloon."
] |
[
"What is worse on our skin, a strong acid or a strong base?"
] | [
false
] | null | [
"\"Acids eat you from the inside out, bases eat you from the outside in\". I'd be more concerned about bases, high molarity sodium hydroxide will turn you (quite literally) into soap via saponification if you get it on you."
] | [
"This happened to me in my analytical chemistry lab way back when I was learning proper handling. I got a drop of NaOH on my finger and immediately washed it off with water, only to find my finger tip felt \"greasy\". It was the fat of my skin being turned into soap! It was just a little bit, no lasting damage, but... | [
"Did it hurt...?"
] |
[
"Doctors: what is your thought process when choosing an antibiotic for patient?"
] | [
false
] | [deleted] | [
"Antibiotic choice is predicated on a number of factors. There are a number of major classes of antibiotics (penicillin derived antibiotics are only one such class), each of which works in a different mechanism that lends itself towards different biologic activity. Efficacy is certainly the first thing you look a... | [
"Experimental Pharmacologist, infectious disease.",
"If taught med students on this. Its fairly standard in theory but in practice some tend to ignore the guidelines. The theory is, you use as much information as you can to predict; Sepsis with skin infection - mostly likely gram + 50-60% chance of S. aureus, 5-1... | [
"Recent Pharmacy Grad-",
"This is how we're taught in school, and yes in practice its like pulling teeth sometimes to get physicians to buy into that idea. In just my last year of school, I had to talk 3 doctors out of using Tigecycline first line in patients. For those that don't know tigecycline, its a very i... |
[
"Is it feasible for a digital cameras to use cheaper lenses with less glass and have the distortion removed via software after it is extracted from the sensor?"
] | [
false
] | Camera lenses can be very expensive, they can contain many pieces of glass to remove distortion and all that extra glass can increase the cost significantly. I was wondering if it was possible for a lens to contain fewer pieces of glass, and therefore be cheaper, and instead of correcting the distortion with extra glas... | [
"It's generally possible to correct all manner of imaging defects (geometric distortion, lens blur, motion blur, noise, etc.) to varying degrees, but in all cases it' s a lossy process.",
"If your only distortion is geometric, and you otherwise have a sharp lens and a great sensor, then you can certainly invert t... | [
"Nothing beats a good piece of glass"
] | [
"Geometric distortion (and to a small extent) chromatic aberration can be corrected digitally, with some loss of detail due to interpolation. But spherical aberration, coma, diffraction, and flare all reduce the amount of information reaching the sensor. Perhaps lenses are being designed for special purposes that p... |
[
"Most soaps advertise as being able to get rid of 99.9% of germs. Do our bodies do the same when dealing with viruses/bacteria, or do we eliminate them completely?"
] | [
false
] | null | [
"Soaps work by breaking down proteins that form the outer shell of “germs”. ",
"I don’t think I see soaps often claim to kill 99%, but disinfectants and sanitizers do claim this. These work in a similar manner, and often these claims require contact with the surface being disinfected to remain in contact with the... | [
"Doesn't detract from your point, but a quick correction: most soaps are bactericidal by virtue of their surfactant and detergent properties. They don't break down proteins; they disrupt the cell membrane/wall."
] | [
"Thank you for this. I was sitting here aggravated but didn’t really know if I felt like getting into this discussion."
] |
[
"How close could a rogue planet feasibly get to us or our solar system without being detected?"
] | [
false
] | null | [
"Why are people answering with \"that can't happen?\"",
"A planet-sized mass that was ejected from a solar system or formed outside of one could be orbiting the galaxy and its orbit around the galaxy could eventually intersect with our solar system's orbit around the galaxy.",
"Our solar system orbits the milky... | [
"\"No chance of a rogue planet because planets orbit stars\" If that's what you believe I don't want to listen to your podcast, Planets are knocked out of their star's gravitational influence all the time. "
] | [
"\"No chance of a rogue planet because planets orbit stars\" If that's what you believe I don't want to listen to your podcast, Planets are knocked out of their star's gravitational influence all the time. "
] |
[
"Sequenced rice genome shows rice cells have more genes (50,000) than humans (26,000). Does this mean rice are more evolved than humans?"
] | [
false
] | 1) Does this mean that the rice genome is more complex? 2) Do we have to abandon the idea that the more genes an organism has, the more evolved it is? | [
"No. # of gene does not represent how far you've evolved.",
"Also what you mean by \"more evolved\"? Some bacteria can undergo a generation every 20 minutes, does that make them more evolved than everything else on Earth?",
"The reason they have more genes is because they're plants.....which in general have mor... | [
"So in essence, plants are genetically more complex because they are biologically more complex forms of life?"
] | [
"\"more evolved\" is subjective. ",
"Yes, rice dna is more ",
" than human dna. An onion is actually 12 times more complex than a human dna, but as you can probably guess, we are more complex creatures than an onion. The reason is that a large portion of an onion, or rice's dna structure, is effectively, ",
"... |
[
"Why does more drag on the fins on a rocket provide more stability?"
] | [
false
] | I was reading this article and the topic came up. Why does more drag on the fins mean more stability for the rocket? | [
"Simple answer: because drag slows the fins, keeping them directly behind the head of the rocket. Any time it starts to veer off course, the fins move back behind the head again and straighten it's trajectory back up. It's the exact same concept as fletchings on arrows that have been used for tens of thousands of y... | [
"Drag is a force parallel with the flow so no I'm not. And fins are airfoils. Flat plates, arc, and diamond cross sections are all used depending on how simple the rocket is and what Mach regime the rocket flys in and are all considered airfoils. A simple way to think about it would be to look at the drag and lift ... | [
"Fin drag is only a minor component to the stability. It's the fin lift that does the work. As long as your Center of Gravity is in front of your Center of Pressure you will be stable. If the rocket gets to a positive angle of attack the fins will generate lift, a force perpendicular to the airflow. So for a positi... |
[
"Why isn't a Bose-Einstein condensate get talked about much in lower level science classes even though it's considered a \"state of matter\"Or is this different than being a solid, liquid, gas, or plasma?"
] | [
false
] | null | [
"Just to name a few, some other phase transitions are:",
"superconductivity",
"superfluidity",
"the ",
"ferromagnetic/paramagnetic",
" transition."
] | [
"Just to name a few, some other phase transitions are:",
"superconductivity",
"superfluidity",
"the ",
"ferromagnetic/paramagnetic",
" transition."
] | [
"This all may be off topic for this sub (its rarely the scientists directly making decisions about what topics are taught or not taught in schools, after all).",
"On the assumption that it's okay for a science teacher to respond to this question: Much of what I do involves helping children understand the world ar... |
[
"Has nuclear weapons testing had any appreciable effect on the planet’s background radiation and/or surface temperature?"
] | [
false
] | In the 20th century, over 2000 nuclear bombs were detonated in unpopulated areas. We know that the bombs in Nagasaki and Fukushima left many people who were not in the immediate fallout to suffer (and often die) from radiation sickness and terrible burns. As the test sites were far away from human habitats (namely the ... | [
"As the test sites were far away from human habitats (namely the Pacific Ocean and depopulated Kazakhstan)",
"Or Nevada. Not that far away from people.",
"https://www.atomicheritage.org/history/nevada-test-site-downwinders",
"The effect on the temperature is negligible. More general: Direct heat release doesn... | [
"over 2000 nuclear bombs were detonated in unpopulated areas",
"Only about 200 were detonated in the atmosphere. The rest were underground.",
"We know that the bombs in Nagasaki and Fukushima ",
"I assume you mean Hiroshima...",
"blasts would have dissipated across the planet and its atmosphere",
"Fallout... | [
"In terms of total radiation dose the impact is small (with some local exceptions: see above).",
"In terms of health effects, it depends on what model of low-dose harm you use. In the northern hemisphere the amount of radiation that non-downwinders picked up from the testing was not negligible, and the population... |
[
"How can smoking cause cancer years after the smoker has quit?"
] | [
false
] | [deleted] | [
"Ok is your question why smoking causes cancer after years of cessation or are you asking why the risk of cancer from smoking decreases drastically after cessation? ",
"For the first question, cigarettes contain hundreds upon hundreds of carcinogens (stuff that damage your cells) that wreaks havoc in your lungs, ... | [
"Tumors have three stages :",
"Initiation : the cell came in contact with a carcinogenic substance or radiations. The DNA has been altered. At this stage, the cell can either survive or commit apoptosis (programmed death aka suicide). If it survives, the DNA has either been repaired or not. The cell is now initia... | [
"Right now, not really, though I'd try to avoid anything known to be acutely (not developmentally) toxic particularly to immune function, like sources of other smoke in general (not just cigarettes, wood smoke still has toxicants in it), mothballs (napthalene) and many pesticides to give you examples (ie. limit exp... |
[
"What Affects The Rate At Which Objects Fall?"
] | [
false
] | null | [
"Yes, it's air resistance."
] | [
"Yes, it's air resistance."
] | [
"Yes, it's air resistance."
] |
[
"If I demand too much of a certain brain area, like the visual cortex, and get a headache, will it feel first in that exact head area?"
] | [
false
] | null | [
"You can't feel pain in your brain. Headaches aren't inside the brain, they are in the surrounding tissue."
] | [
"you don't get headaches because of using your brain. headaches usually correspond to inflammation (or abnormal activation) of the trigeminal nerve that innervates your face.",
"if anything, you might sometimes get eyestrain headaches from overwork, which correspond to fatigue in eye muscles and tissues."
] | [
"I know that. But I was wondering if the surrounding tissue has some correlation with each part of the brain."
] |
[
"Zeno's Paradox. Does this work?"
] | [
false
] | null | [
"This is not a valid, physical solution. If we look at things classically (pre-quantum mechanics), then a basic assumption is that things move continuously and a most, if not all, of tools that we use would have to be completely redone to use a discrete movement framework. But these tools have given too many correc... | [
"I understand limits. I don't think it's weird that the infinite sum of constantly decreasing numbers tends to a number and doesn't go over it.",
"This is the problem I have. Ok, so we wanna move 10 meters and let's say that takes 2 seconds. Then moving 1 meter would take 0.2 seconds. The problem is that there ar... | [
"If infinite sums say that an infinite number of positive values can add up to a single, finite value, then Integrals say that an aleph 1 amount of zeroes can add up to a single finite, positive value.",
"Yes, to move from point A to point B, we need to hit every value inbetween and there are an uncountable numbe... |
[
"How does soap clean?"
] | [
false
] | title says it all, how does using a bar of soap clean you, on a scientific level? | [
"Soap molecules form micelles around dirt/contaminants/bacteria. A micelle is effectively a ball of soap molecules that surround the dirt and hold it in suspension in the water.",
"The soap molecules have a hydrophobic tail and a hydrophillic head. The heads of the molecules all face outward towards the water, an... | [
"Most molecules can be described as being \"polar\" (which simply speaking means they dissolve in water), or \"nonpoloar\" (which are greasy substances that don't dissolve in water). Washing with water can easily clean the \"polar\" dirt away, but not the \"nonpolar\".",
"Soaps work because they're both polar an... | [
"Soap consists of molecules which have two kinds of ends, one end which \"likes\" water and similar molecules (hydrophilic), and one end which \"likes\" oil and similar molecules (hydrophobic). One of the challenges to removing dirt and some organisms from your skin is that they are oily and repel water, so they a... |
[
"How come skydivers, astronauts and pilots don't suffer from an equivalent of \"the bends\" when they are hurtling towards the ground?"
] | [
false
] | [deleted] | [
"Keep in mind the relative differences in pressure - even if you go into space, you only decrease by 1 atmosphere. But the overpressure at even 100 feet deep (which is well within the reach of a scuba diver) is ",
"over 9 atm",
" ",
"over 3 atm",
". ",
"Edit: Fixed to underwater, not underground."
] | [
"Astronauts (and presumably Felix Baumgartner) do have to worry about the bends, although not when hurtling towards the ground (the bends, if I understand correctly, only occur due to a rapid decrease in pressure. I'm not aware of any equivalent problem for a rapid increase in pressure). Before spacewalks, astronau... | [
"The pressure of water vs. the pressure of air are different."
] |
[
"Does birth order have an impact on someone's personality?"
] | [
false
] | null | [
"the answer is either \"no\" or \"not really\". many studies of this exist, it's an old and popular question. here's one:",
"https://journals.sagepub.com/doi/pdf/10.1002/per.2285",
"there they find no effect of birth order on the Big Five personality dimensions (extraversion, conscientiousness, neuroticism, ope... | [
"https://time.com/5953372/birth-order-personality-traits/",
"I had a college sociology professor who stated order did determine certain personality traits. He gave the specific example that first-born children were more likely to fly a plane with a team, while a youngest child would be more likely to become a s... | [
"Your formative experiences are shaped by the people in your immediate household. No one can deny that.",
"Those experiences are going to be wildly different depending on the number of people raising you, ",
" personalities, and their dynamic.",
"The factors that shape our personalities are so varied and so s... |
[
"When I hear a sonic boom, am I hearing all the sound generated by the speeding projectile over a certain distance all in one go?"
] | [
false
] | This is how I interpret this diagram of a mach cone if we place ourselves at the red dot, but I haven't yet (after some brief internet searching) found anywhere that explains it this way. | [
"No. This is a common misunderstanding about what the source of the noise you hear as the result of the passage of a shock wave is.",
"Those circles don't represent noise as you think of it - stuff like birdsong of even the roar of the plane's engines. Instead, they represent the disturbance of the air generated... | [
"This is really a great explanation, thank you. I can see now why I kept seeing bow-wave comparisons in articles.",
"I just have one question: what is a physical discontinuity?"
] | [
"A discontinuity is when the value of some property changes instantly. In reality, there don't appear to be any real discontinuities, but some things can change so quickly or across such short distances that they are very, very close to the concept of a mathematical discontinuity, and we use that as an approximatio... |
[
"Why is exercise painful?"
] | [
false
] | Exercise is supposed to be healthy; so why is it painful? Surely if it increased our chances of survival, wouldn't it make more sense for exercise to be pleasurable, thus encouraging us to do it more often? Are there any benefits at all to having it this way? | [
"Exercise involves slightly breaking down muscle tissue by forming micro-tears. Then the body rebuilds the muscles, over shooting a bit so that it can deal with the increased load. Repeat many cycles of that and the muscles become stronger."
] | [
"For some people it is pleasurable... You produce endorphins when you exercise which give you a feeling of well being... When I am stressed out I go lift weight or run and it defiantly improves my mood.",
"You are probably out of shape and trying to push yourself too much thus having cramping and pain."
] | [
"Due to the excess demand for energy in exercise, pyruvate is reduced to lactic acid in anaerobic respiration in muscle cells. This happens when not enough oxygen is present. Lactic acid causes a feeling of soreness and pain.",
"Can someone please go in more detail? Or correct me if I'm wrong. It's been a while >... |
[
"If something is being changed over time by Oxygen (and its binding properties), it is oxidized. What happens when Fluorine (a much friendlier element) does the same thing? (What is it called?)"
] | [
false
] | Also, are there any really interesting cases of fluoride interactions in daily life? | [
"Fluorine has a higher electronegativity than oxygen",
", and is a stronger, more reactive oxidant than oxygen. The term ",
", or ",
" has a specific meaning apart from its association with oxygen:",
"http://en.m.wikipedia.org/wiki/Oxidizing_agent",
"An oxidizing agent (also called an oxidant, oxidizer or... | [
"In my line of work we call it fluorination, emphasis on the n for the atom not the ion.",
"In the molten salt reactor experiment when they used H",
"+H2 to create a reduction oxidation reaction it was called the hydro-fluorination process.",
"Its also very acceptable to call it oxidation as well. Oxidation ... | [
"The idea that it is friendly to other atoms by binding to them often (due to its electronegativity).",
"Especially because it is so friendly that hexafluorides are a possibility."
] |
[
"Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"No, the only limit is what you choose to call a \"moon\". Each of the ice particles in Saturn's rings is technically a moon, and there are a squijillion of them."
] | [
"Yes. In fact, it already is; it's just barely noticeable - although it should be noted that it will oscillate with a period of twice the tides. High tide is when the moon is either overhead ",
" directly opposite, while gravity will be strongest with the moon directly overhead but weakest with it on the opposite... | [
"It'd probably help if you could link to the particular article you are talking about. People are mostly interested in studying the climate and atmosphere of Mars to understand how it works on Mars, rather than to apply back to earth directly."
] |
[
"If we can find hundreds of exoplanets orbiting stars hundreds of light-years away, why do we have a hard time conclusively confirming Planet Nine within our own solar system?"
] | [
false
] | [deleted] | [
"That's not an ideal comparison for a few reasons:",
"-There are billions of stars to look at, a small fraction have detectable planets but most of them do not. There is only one sun so we can't get statistics on multiple versions of our solar system.",
"-Most planets are detected by the light they block as the... | [
"We have discovered 56 exoplanets within 10 parsecs. It's likely that there are actually thousands of exoplanets within that distance. So we have only discovered a few percent (perhaps 1-5%) of the exoplanets within 10 parsecs.",
"If there is a 9th planet in our system, then we have discovered 8/9 of the planets ... | [
"There are lots of planets, so finding many planets isn't hard. Confirming or refuting the existence of a specific planet is much more difficult, however.",
"Planet 9 is far away, if we knew exactly where it was we could just look at it with a telescope powerful enough to see it (which are unfortunately few) and ... |
[
"I've heard that humans share 50% of our DNA with bananas. What living organism on Earth shares the LEAST amount of human DNA?"
] | [
false
] | [deleted] | [
"It's important to realize that the 50% figure refers to actual ",
", not all DNA. A large majority of our genome is not part of any gene, and the same goes for bananas. You wouldn't even be able to compare these non-coding regions in any meaningful sense, since our genomes are about six times larger than those... | [
"bananas are Eukaryotes, just like us. This is one of the three most fundamental groups of life that we recognize, alongside Archaea and Bacteria. Eukaryote cells all have nuclei and other organelles enclosed within their own membranes, and that's what we share with bananas. (aside, it's pretty crazy that 50% of ou... | [
"I think I read that Archaea might be more closely related to eukaryotes than bacteria, but maybe someone with an actual biology degree can answer with more certainty.",
"Indeed, it is now widely theorized that eukaryotes evolved from archaea. A group of archaea called the \"Asgard archaea\", which were discovere... |
[
"Does an inductor coil become a capacitor when 1 of the middle loops is cut?"
] | [
false
] | It would have no direct path for electrons to cross between the 2 sides of the wire (cut somewhere deep in the coil) so to prevent buildup of static charge the 2 now separate but concentric coils should become oppositely charged, total neutral charge. Do some capacitors work this way? How efficient are they compared to... | [
"It would act like two inductors attached to each side of a very small capacitor. So the capacitor portion would have a huge reactance and you'd very likely end up with a device that had the performance characteristics of an open circuit since the two 'filters' would have an overlapping frequency range."
] | [
"The physics behind your question is sound, but I have a feeling that the capacitance of these two half-coils would be very small.",
"The rest of your questions would be better answered by an electrical engineer."
] | [
"The capacitance would be tiny depending on separation distance and surface area on the separation, which would be very small. Ideally a capacitor should be two parallel sheets. "
] |
[
"When I fire a gun does the bullet slide down the barrel, or does it float/fly down the barrel?"
] | [
false
] | [deleted] | [
"Most bullets are slightly wider than the barrel diameter. For example, the .45ACP bullet is .452 inches in diameter, while the bore is generally (and this varies slightly depending on the gun, and rifling type) .451 inches. The 21,000 psi in the chamber squeezes the bullet into the rifling, preventing gas blow by ... | [
"In modern guns the bullet is squeezed through the barrel.",
"In the era of muzzle loaded flintlocks and similar firearms the bullet would be smaller than the barrel, in order to be able to be loaded. Sometimes wadding would be added to help the bullet fit more snugly. This is necessary for two reasons. One, if t... | [
"If you notice the last paragraph of that article, jacketed bullets fired out of rifles are almost always larger than the bore and swage to fit."
] |
[
"Are there any languages that are easier or harder for AI systems to sufficiently \"learn\" for translation purposes? If yes, what are the aspects of a language that make the process easier or harder?"
] | [
false
] | null | [
"There aren't really individual languages that are inherently more difficult to learn, as the purpose of modern machine-learning is that we automate the process by which we learn the rules. There are some major practical considerations:",
"Furthermore, translation is between ",
" of languages, and there are pai... | [
"In Google's instance, one strategy they used to use is they used to train two pairs of neural networks for each language, one for encoding and one for decoding that work with concepts themselves, and then have a common neural network that works across all languages that only deals with the concepts. What they then... | [
"Certain languages, particularly artificial languages, have features whereby you can determine the function of the word just by inspecting it.",
"Esperanto is one such language. All singular subject nouns end in -o (-oj for plural). All singular object nouns end in -on (-ojn for plural). All verbs end in -is (... |
[
"How does a dried, packaged seed \"know\" when to grow once I've planted it in the ground?"
] | [
false
] | [deleted] | [
"http://www.ehow.com/about_6695705_respiration-germinating-seeds.html",
"Respiration begins when a seed absorbs water. The enzymes inside seeds have to be in suspension to function. Activated enzymes start respiration and use organic matter stored in the seed during respiration to make ATP molecules needed for gr... | [
"So are said enzymes in the ",
"germ of the plant",
"? "
] | [
"Imbibition (\"drinking\" or absorption of water) is part of it, but many seeds also have complex germination inhibition systems in place. Some seeds require stratification (to be sown in cold, wet soils over winter, for example) that \"burn up\" various germination-inhibiting compounds. Others require scarificatio... |
[
"Is every Subatomic particle moving at the speed of light at all times?"
] | [
false
] | Ive wondered this for a while now. This question only includes smaller subatomic particles and not matter. | [
"No. Only things without mass, like photons, can travel at the speed of light."
] | [
"There are several kinds of neutrinos. We observe that they change between these kinds. Therefore the neutrinos must experience time, so they can't be traveling at the speed of light - so they have mass."
] | [
"Massless particles have to move ",
" the speed of light.",
"Massive particles have to move ",
" the speed of light.",
"So no massive particles are moving at the speed of light, and most of the subatomic particles we know of are massive, including quarks, electrons, and various other things which make up mo... |
[
"If I had a treadmill set at a 5% upward grade and someone ran on it for a mile, would they be expending the same amount of energy running up a perfectly straight track that is angled at a 5% grade for a mile?"
] | [
false
] | It seems like it is the same, but the problem is that if you take the initial and final state conditions, the person running up the track has gained some potential energy, the person on the treadmill has not moved. | [
"Even when we run outside we are still on a treadmill, it's just that we are going the same speed as it and we call it Earth. There isn't enough room on a treadmill to travel the same speed as the belt (if the belt were 10 miles long you would eventually feel no movement as you stood there and you could take off ru... | [
"For a treadmill to accurately simulate running it would need to have a feedback response that can adjust speed to exactly counter your forward movement in a natural way. If you could confidently start sprinting on a treadmill and the belt would move at that exact moment to compensate then you would be using the sa... | [
"You're right. It's misleading. I got off track relating it to a gravitational problem. What I should have said was yes but only in specific circumstances beyond just wind. I'll edit."
] |
[
"I just learned about the sinoatrial node. Why does the heart stop in cases like fatal brain aneurisms if the heart has its own pacemaker?"
] | [
false
] | If I understand correctly, the sinoatrial node is sort of like a natural pacemaker that generates an electrical impulse and stimulates the heartbeat. I read that even if you separate the heart from the brain, the heart can keep on beating because of the SA node. What is the reason that, for example, in the case of a fa... | [
"Not a pathologist, but I think it goes something like this:",
"In a brain aneurysm, the leaking blood is pumped into the space between the brain the skull. This puts pressure on the brain and the vessels delivering blood to the brain, reducing blood flow to the brain. This causes the brain cells to die. If the m... | [
"In cases of ",
" as with (in your example) massive aneurysmal subarachnoid hemorrhage, trauma, or other causes, the heart loses its greatest ally in the cause of controlling cardiovascular system function.",
"Normally a combination of sympathetic and parasympathetic inputs to the heart and to the circulatory s... | [
"Because the heart also needs other things to function, such as nutrients, and getting adequate quantities of nutrients into your body requires a complex system of actions that involve your brain and digestive system. Similarly, elimination of waste products requires a functioning brain, liver, and kidneys.",
"If... |
[
"What happens to the muscle and bone when a finger is jammed?"
] | [
false
] | Are they sprains or strains and what does it "look like" on a muscular/skeletal level? Bonus question: Why do I feel the need to pop the finger ever 30 seconds to a few minutes? When they are uninjured I pop them maybe 4-5 times a day. | [
"There aren't any actual muscle groups in the fingers themselves like you have muscles resting on your arm that bends your elbow. All the muscles that control the fingers are found in your forearm. Each finger has two groups of tendons extending from the forearm, through the wrist, and onto each finger bone. Imagin... | [
"The space in between each finger is put under a lot of pressure. There are nerves, blood vessels, and connective tissue in joints. So the swelling is the result of the crushed vessels and the tenderness is from the nerve cells being cramped up by the large increase in fluid in their tissue. The fluid is a mix of b... | [
"My mistake, it's been years since my anatomy and physiology class. Thank you for catching that. I think there might also be muscles in between each metacarpal. "
] |
[
"Why do we use sine to calculate refractive index?"
] | [
false
] | In class today I learnt about refractive index. We only got as far as a practical and learning the equation (n = sin(i) / sin(r)). I understand why we would need to calculate refractive index, but I don't understand why we use the sine function in the equation. I always thought sine was a wave, so if anyone can explain... | [
"The sine function gives a wave when plotted in a graph, but it is also the ratio of two specific sides of a triangle for a given angle. The calculation for refraction index uses the second usage of sine. "
] | [
"Snell's law can be derived from Fermat's principle or Huygen's principle (or a few other ways I'm sure, but I've only had geometrical optics).",
"The definition of the refractive index of a medium is",
"n = c/v",
"Where c is the speed of light in a vacuum, and v is the speed of light in that particular mediu... | [
"or a few other ways I'm sure, but I've only had geometrical optics",
"If you want to be really fancy about it, you can derive Snell's Law from the boundary conditions on Maxwell's Equations as well (and the law of Reflection, and about all the rest of optics; that derivation was when electrodynamics really \"cli... |
[
"Why is Haloperidol absorbed more slowly in individuals with Schizophrenia?"
] | [
false
] | So I was reading about some anti-psychotic drugs since I'm not in the medical field and didn't get a joke my friends told, but just read that Haloperidol is absorbed much more slowly in individuals with schizophrenia. This really got me wondering if that had anything to do with Schizophrenia directly or if had more to ... | [
"I'm having trouble finding a primary source with that information, but ",
"this paper",
" did a retrospective analysis on a related drug (paliperidone) and found that the pharmacokinetics were influenced by patient BMI, injection site, injection volume, needle length, and creatinine clearance. So it could be d... | [
"Actually I'm at work right now and there aren't any psych consults to see so I'm looking at our med search to see if I find anything.",
"Only thing I really see is that oral dose is initially higher for schizophrenia then acute psychosis according to manufacturer label. ",
"IM as decanoate is available that is... | [
"Actually I'm at work right now and there aren't any psych consults to see so I'm looking at our med search to see if I find anything.",
"Only thing I really see is that oral dose is initially higher for schizophrenia then acute psychosis according to manufacturer label. ",
"IM as decanoate is available that is... |
[
"Why Fluorine is a Hydrophobic compound ?"
] | [
false
] | [deleted] | [
"It has a strong ability to withdraw electron density from what it bonds with. In the case of Teflon (or PTFE), you have a situation where two fluorines are symmetrically bonded to one carbon; both the fluorines are pulling the electrons towards them equally strongly. This limits the electrons' availability to ta... | [
"Well, you're comparing apples and oranges there. It's not the Mg-F or Mg-O bond that's important here; it's the additional O-H bond, which is a polar; water, being polar, will naturally be attracted to it."
] | [
"Well, you're comparing apples and oranges there. It's not the Mg-F or Mg-O bond that's important here; it's the additional O-H bond, which is a polar; water, being polar, will naturally be attracted to it."
] |
[
"[Biology] Why do we sleep better with the lights off then with the lights on?"
] | [
false
] | Is this a obtained preference or does this go back to when we slept outdoors during the night or in caves? | [
"We produce melatonin from our pineal gland when its dark. It regulates our sleepfulness/wakefulness. Yes it has everything to do with our baser human instincts, as does every aspect of our lives. ",
"We are animals pretending to be above organic lifeforms, but alas, we are still animals."
] | [
"You also partially open your eyes at times like during REM cycles. REM=Rapid Eye Movements. You go through different stages of sleep. Each cycle lasts about 3 hours. Wearing an eye mask or room darkening curtains helps with this for day sleepers."
] | [
"This is all due to our evolutionary ancestors who had a pineal eye instead of a pineal gland. The pineal eye has photoreceptors that help regulate the sleep/wake cycle and assist in managing internal body temperature. Our ability to sleep better at night is a holdover from \"lower\" animals. Melatonin and cortisol... |
[
"Saturation: is it possible to saturate water with several substances?"
] | [
false
] | For example, let's say that the saturation point of sugar in water is 50g, and salt is 100g. If I were to dissolve 50g of sugar in 1l of water, how much salt could I add? Is it the full 100g, or is it less? | [
"I'm not entirely sure about this example, however adding impurities in your solution can interact with whatever you are trying to dissolve and make them more soluble. "
] | [
"Sugar does not \"dissolve\" in water but it forms several equilibriums:",
"http://users.wmin.ac.uk/~perryd/ch/glcrings.gif",
"So, what's the effect of salt saturation on a water glucose solution you may ask.",
"Simple, since glucose just make an equilibrium with water while sodium chloride in fact \"dissolve... | [
"Reasonably good explanation of ion activity and salting out effect and their effect on solubility. For point of clarity - glucose does dissolve, it just doesn't do so by ionization like acids, bases and salts. Rather it does so by hydrogen bonding - the same type of reaction that water has with itself. Further,... |
[
"Is there any evidence to suggest that galaxies are just young super-massive \"solar\" systems?"
] | [
false
] | While looking at the formation of solar systems and the current state of galactic formations I noticed that they both appear to form similarly from dust and particles eventually combining around a large gravitational object at the center. Could galaxies just be young super-massive "solar" systems so-to-speak? Obviously... | [
"I don't understand what you're asking really.",
"Imagine it this way: the moon orbits the earth, the earth orbits the sun, the sun orbits the black hole at the center of the Milky Way, and the galaxy orbits the center of mass of the local galaxy cluster. That's the way things are. ",
"Are you asking if all the... | [
"Sorry for the lack of a straightforward question. What I'm trying to ask is that given enough time (on the scale of billions to trillions of years) if all the solar systems within a galaxy would roughly form into a large, multi-billion planet, macro solar system with the black hole at the center. Given the time it... | [
"all the solar systems within a galaxy would roughly form into a large, multi-billion planet, macro solar system with the black hole at the center. ",
"That's what we already have.",
"Unless you mean, will all the stars burn out and all the planets stop orbiting stars and just orbit the block hole? I don't thin... |
[
"If you stacked a lot of microscopic organisms, would you eventually be able to see them? What would they look like?"
] | [
false
] | Assuming they don't move or run away, what would happen if you stacked (or piled up) a of microscopic organismic or just microscopic "things" in general. Disregarding the improbability/impossibility of finding that many of the organism, would you eventually pile up enough to be able to see them? Would it look like a so... | [
"This actually happens all the time, especially in labs when you're growing up a culture of bacteria to use for something. ",
"And you can definitely see them!",
"What they look like depends a lot on what species of organism it is and what environment it's growing in. A lot of bacteria will be a kind of gooey s... | [
"So mold is basically what the original post was talking about? Aren't we all giant 'stacks' of microscopic bacteria?"
] | [
"Well, not bacteria. But stacks of microscopic cells would be accurate. Bacteria is just a particular type of cell."
] |
[
"What exactly can quantum computers do?"
] | [
false
] | I know they're based off of quantum mechanics, but I'm a little unsure about their purpose. Are they able to replace modern computers or are they being sought after primarily as an instrument? | [
"I will answer your question after a few paragraphs of background. Yay learning!",
"Computer scientists have a theory of complexity with various complexity classes. We take some problem (such as \"what are the factors of this number?\"), and classify it according to properties of some algorithm known to solve it.... | [
"They can do precisely the same things classical computers can. Further, they'll have less memory, and each operation will be much slower.",
"So why would people be interested? Because while they're slower and smaller, they can do some things with many fewer ",
"-operations and ",
" bits than we can do wit... | [
"Sure. There's a set of problems that we can solve efficiently with a classical computer, and a set of problems that we can solve with a quantum computer. There are problems that we know are in the latter set which we do not know are in the former set. This means that there are problems we know how to solve efficie... |
[
"Does the amount of salt in water effect the time it takes to evaporate?"
] | [
false
] | like, does more salt make water take longer to evaporate? | [
"Yes, all things being equal . This is mostly due to the ",
"colligative property",
" of boiling point elevation/vapor pressure depression. It's important to keep in mind that when you're trying to predict the rate (kinetics) of a physical process, ",
" things can be a factor. Generally, rate of evaporation w... | [
"Yes, because",
"1) some of the heat energy is absorbed by salt ions, which do not evaporate",
"2) water-salt interactions are stronger than water-water interactions, so as the amount of water decreases, the strength of adhesive forces keeping water molecules in liquid phase increases",
"3) water only evapora... | [
"Yep, like other people have said. It's not a particularly strong effect for amounts of salt you're likely going to run into. So it takes a pretty careful measurement to really notice the difference. you're not really going to notice it very much in normal life."
] |
[
"Why didn't the Greenland ice sheet melt after the ice age?"
] | [
false
] | Part of the Greenland ice sheet is at the same latitude as where the ice sheets that covered Canada and northern Europe were and those melted, so why not the Greenland one? | [
"Jet streams. The earth isn't a static thing, hot air is blown via jest streams across the globe, cooled and recycled, like an AC.",
"Greenland wasnt getting an equatorial stream north, the air that hit europe ice cooled the air, and warmed the ice, causing it to melt over a few thousand years.",
"That loss of ... | [
"There's also the Gulf stream, north Atlantic drift, and Labrador current. the Gulf stream bring warm water up the eastern seaboard, turns out into the Atlantic at the boundary between it and the Labrador current, and the goes across the ocean to warm much of Europe. The Labrador current brings cold Arctic water so... | [
"You can't equate latitude directly with temperature, due to jet streams and ocean currents. The ",
"Gulf Stream and North Atlantic Drift",
" bring warm water (and accompanying air masses) to Europe and along much of the coast of North America. Note in the image that Greenland is bordered almost completely by a... |
[
"2 part question here: First, how does a black hole become charged? And second, why do some rotate but others do not?"
] | [
false
] | Basically, I just want to know what the mechanism behind "charging" a BH is, because I thought that all matter was ripped apart to the quark level or whatever. How does is gain a charge? And what causes some to rotate but not all of them? | [
"Just toss electrically charged matter into it so that it gains a net charge. If you initially have an electrically neutral black hole, perhaps made by the gravitational collapse of an equal number of protons and electrons, then just shoot an electron beam at it. By conservation of charge the charge of those electr... | [
"Most black holes probably rotate—",
"some even near a fundamental maximum",
"—because the stars that produced them rotated and angular momentum is conversed in all of physics. A rotating black hole is a strange beast with some truly bizarre properties."
] | [
"All black holes rotate. Some rotate more than others, but everything rotates a little, and when you compress it that much, it will start rotating very fast. We study non-rotating black holes because the symmetry makes the math easy, not because they're a thing."
] |
[
"Does wind have the same effect on light that it does sound? Why or why not?"
] | [
false
] | We've all heard that wind can interfere with and even direct sound waves, but if all that's true then why wouldn't wind affect light? "Light is both a particle and a wave." Okay, well we KNOW that wind can carry particles . . . And if wind can carry a sound wave, why not a 'light wave'? Forgive me if this a stupid qu... | [
"The main difference is that the gas particles carry sound waves, while light is a propagating electromagnetic wave that travels ",
" the medium, and not ",
" the medium.",
"The only way that there would be a visible effect by wind would be if it somehow changed the refraction of the air, like in a ",
"mira... | [
"so the mistake you are basically making is thinking that by 'a particle' the person means is like a ball that you can pick up and throw around. ",
"what they in fact mean when referencing wave/particle duality is that it doesnt follow the rules of the macroscopic world. ",
"when you look around yourself in th... | [
"Light is infact perturbed by air currents, just usually not enough to notice. When using an optical interferometer for example, if you clap or breathe near your photo detector the intensity signal will oscillate up and down as the laser source becomes unalligned and realligned with the semi conductor.",
"This i... |
[
"Is there definitive scientific evidence that the universe is, in fact, infinitely expanding?"
] | [
false
] | Hope it's not a dumb question. | [
"There's clear evidence that the expansion is happening and that it's accelerating. ",
"If we assume this will keep going then eventually all galaxies become isolated from each other and something like a ",
"heat death",
" occurs. ",
"But no one knows if the expansion will keep on going. We don't even hav... | [
"Didn't know the indefinite expansion was related to the maximization of entropy. Is it really related? I thought it wasn't."
] | [
"It's not connected, it's just a side effect if you wait long enough. ",
"In an eternally expanding universe the energy density just keeps dropping, causal domains becomes smaller and smaller and everything cools and stop interacting eventually. We asymptotically approach absolute zero.."
] |
[
"How are thermodynamic quantities calculated? Such as enthalpy, internal energy, entropy, chemical potential, etc."
] | [
false
] | null | [
"This is a good question. Here's the general procedure for simple thermodynamic systems:",
"First you start by defining your ensemble. What are you dealing with, what are your independent variables, what's being held constant, etc. For example, you might say that you have a box of gas where your independent varia... | [
"To give a slightly more compressed answer.",
"The way we go about calculating various thermodynamic variables is by relating them back to quantities we can readily determine. For instance variables we can easily measure in a system are things such as pressure, temperature, volume, etc. ",
"So what we do is ... | [
"It is conceptually simpler to start from statistics: start with the multiplicity Omega of macrosystems. Two systems with the same temperature have the same relative change in Omega with internal energy. Entropy is proportional to log Omega."
] |
[
"The electromagnetic field is one where the electric field is 0 but the The Higgs field has a non-0 value everywhere. What does that mean? It's an energy field with constant charge?"
] | [
false
] | null | [
"It's simpler than that.",
"The the level of water on a swimming pool. This is a field, it's a number that takes some value everywhere on the lake. If you have a windy day, this number can change very dramatically because you can have waves forming, but if you average out the waves, you have something which is th... | [
"where the electric field is 0 but the The Higgs field has a non-0 value everywhere. ",
"This is not a description of an electromagnetic field. It is a description of the field configuration that makes up the (classical) vacuum."
] | [
"is the \"expectation value\" a number that represents energy?"
] |
[
"Help me reddit! Wondering why water always feels colder than the room temperature. Wet fabric always feels cool. A glass of water left in a warm room feels cool for hours after. What's the deal?"
] | [
false
] | null | [
"Water simply has a better capacity than air to absorb heat from your fingers. Water has a much higher ",
"thermal conductivity",
" than air. Air will suck ",
" heat from your hands considering the difference between room temperature and body temperature. Water will absorb ",
" heat with the same temperatur... | [
"On top of its greater heat capacity, as unonimus said, evaporative cooling also leaves water cooler than room temperature. This is much more of an effect if the water is in a thin layer (i.e. wet fabric), because it has a much greater surface to volume ratio."
] | [
"There's two different phenomena at work here. The first is thermal conductivity and thermal storage capacity. The second involves phase change and heat transfer.",
"Wood has little capacity to either store heat nor conduct it. It is somewhat insulative. All insulators have that property, and air is one of the be... |
[
"Do computers access familiar memory addresses faster the second time around?"
] | [
false
] | It appears when I open a file a second time around, it opens faster. Why is this? Or is it my imagination? | [
"Computers usually cache oft-used data in a portion of memory that's much faster to read than your mass storage device - but the memory itself is not the same type. Most operating system will cache things like opened files in RAM and will keep them there until the memory is needed by other things. Therefore, the fi... | [
"From your point of view - yes... but the third time is a crap shoot.",
"For files especially there's a lot of places that a computer will tuck data about that file that are much higher speed than actually reading it from the disk. Even the disk itself has some RAM on it that's a few orders of magnitude faster t... | [
"/u/IronMew",
" partially explained caching, but didn't take it to its most effective level. ",
"A computer typically contains several levels of cache memory. The lowest levels are inside of the microprocessor itself. Once data/instructions have been fetched from RAM, it will store a copy on the chip itself. I... |
[
"To increase power, why do gasoline engines add to the number of cylinders while diesel engines add to the size of the cylinders/engine block?"
] | [
false
] | What would happen if you modeled a diesel engine like a V12 sports car engine? Conversely, if you modeled a gasoline engine like a large Detroit diesel engine? | [
"Diesel engines compress the fuel air until it combusts. Petrol engines compress them less and use a spark to combust them. So in a diesel engine you get more benefit from compressing more fuel/air to combustion so bigger cylinders = more power because you get longer strokes on the piston.",
"For petrol engines y... | [
"Not quite. A diesel compresses air until it gets very hot and then injects the fuel into the hot air causing it to burn. The fuel is not mixed with air ahead of time. "
] | [
"they don't necessarily, The GMC Duramax diesel is comparable to their gasoline engines in bore to stroke ratio and displacement. Diesel engines have to be stronger because of the increased force of compression which makes them heavier than a comparable gasoline engine."
] |
[
"Has any real scientific research been done to study meditation, yoga and other mystical phenomenon?"
] | [
false
] | Amongst supposed spiritual and mystical phenomenon meditation and yoga seem to be fairly well accepted as having tangible benefit to the practitioner. Has there been any studies to measure or validate their effectiveness and/or to try to discover their physiological mechanisms. Obviously some elements of yogic practice... | [
"I feel almost guilty doing this, and if I'm in error I'm very sorry, but that doesn't sound like a medical abstract to me. It reads like some of the crazier stuff from my liberal arts days. Especially the criticism of things as \"reductionist\" and the frequent use of the word paradigm.",
"Can I have a link to t... | [
"There's been quite a lot of research into exactly what's happening in the brain during meditation. One example would be this study:",
"http://journals.lww.com/neuroreport/Abstract/2000/05150/Functional_brain_mapping_of_the_relaxation.41.aspx",
"There are a bunch like that. Typically they get some practitioners... | [
"A study from earlier this year on the impact of an 8 weeks training course in Mindfulness Based Stress Reduction (a secular meditation technique) on the brain.",
"Impact of Mindfulness-Based Stress Reduction training on intrinsic brain connectivity.",
"findings suggest that 8 weeks of mindfulness meditation tr... |
[
"Do germs end up in the air after they have settled?"
] | [
false
] | Not sure if I posed the question correctly, but, I'm basically wondering how germs work, particularly COVID at this time. Suppose there was a warehouse of boxes just completely contaminated with COVID and they transferred it to a second warehouse, which previously had no COVID whatsoever. What would be the risk of some... | [
"Not highly likely, due to adhesive forces that would bind the virus to surfaces. One way that this could happen is the virus settles and adheres to some loose particulates (e.g., dust), which can be kicked up into the air, and carry the virus as a vector."
] | [
"In theory yes,but viruses also DIE fairly quickly if they dry out, so it's very difficult to reconcile those factors. It probably COUlD BE DONE intentionally, but it hasnt been seen with Covid"
] | [
"Covid is not a germ, it is a virus. Corona viruses only propagate through fairly large water droplets, and briefly in surfaces. They have never been seen to pass through the air in atomized air (some viruses do). Hence the 2m social distancing argument, since a cough or sneeze falls to the ground in less than th... |
[
"Why does fire behave this way in zero gravity?"
] | [
false
] | null | [
"The flame is actually hot gas undergoing convection. Convection depends on the ",
"Rayleigh Number",
" which depends on gravity. Zero gravity means 0 Ra Number, which means no convection, giving a spherical flame."
] | [
"I can't do any better than ",
"Wikipedia",
"."
] | [
"I was confused until I realised you weren't talking about the Reynold's number... there are too many numbers..."
] |
[
"If a car acts as a faraday cage, why can I get radio signals through the antenna?"
] | [
false
] | And why does lightning not propagate through the antenna? | [
"Well, ideally, the antenna will be on the outside of the car. Then the signal will be carried inside the 'Faraday cage' of the car by wires. (Modern cars tend to have very compact antennas instead of the long whip antennas of yore, but they're typically either on the top of the car, front windshield or incorporate... | [
"I'm pretty sure yoh are picturing EM waves wrong. Amplitude is not a height like it is with say water waves, it has no spacial measurement or size. We merely visualize the amplitude of a EM wave in a diagram as a height, the axis is not distance though but rather field strength. Same as if you plotted say temperat... | [
"I'm pretty sure yoh are picturing EM waves wrong. Amplitude is not a height like it is with say water waves, it has no spacial measurement or size. We merely visualize the amplitude of a EM wave in a diagram as a height, the axis is not distance though but rather field strength. Same as if you plotted say temperat... |
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