title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How many years did it take ecosystems to recover from K-Pg Extinction event (Chicxulub asteroid)?"
] | [
false
] | Hi, I'm doing research for fun stuff. From my understanding of article from Nature, the impact winter after the K-Pg meteor was caused by soot (and/or sulfur) in the atmosphere reducing sunlight penetration. And that the 10-ish years of the impact winter was much more responsible for the extinction event than the impact itself (ie. the sonic waves and tsunamis and heat and magnitude 11 earthquake and stuff). I would like to figure out exactly what the timeline was for the world's recovery after K-Pg. This stuff is surprisingly hard to find, I swear. I found a that said it took 30,000 years for the first microbes to start showing back up again. That feels weird. Why did the article say that the climate would be returned to normal after 10ish years but it still took 30,000 years for microbe life to return? How long was it before the first big trees? How long until everything was more or less "back to normal" in terms of the presence of flora? Are we talking, like, 200 years or 200,000? At what point after K-Pg could I walk outside and see a green landscape? Is this number different for fauna? Like, what's the earliest we saw animals thriving again? I'm going crazy. If you're an expert I'd appreciate book recommendations or articles and whatnot. Point me in the right direction so I don't have to keep hasslin' you :) | [
"The very unsatisfying answer is that nobody really knows. There aren't a lot of fossil beds immediately on either side of the K-Pg boundary, which means we don't really know how long the overall extinction took, let alone how long the recovery was, at least not on a global scale. There are estimates for the length... | [
"",
"I think you're misinterpreting the article. It mentions that it took a long time for life to come back ",
". That's to be expected, as that area was essentially sterilized by the impact",
"That that's not what would have happened all over the Earth. If *ALL* the microbes had died, all life would ha... | [
"Thanks for taking the time to reply. This is still great to know! I'm glad to know that I'm looking at a scientific-community-wide blank in knowledge, and not just the blank in knowledge of my own research, which sometimes looks identical. Have a great day :)"
] |
[
"How did we figure reference temperatures out?"
] | [
false
] | One of the ways to check for the purity of a substance is to boil/melt and check against the expected value,but how do we know the reference in the first place? How do we know that water boils at 100 degrees so we can use it as a reference for tests? | [
"The temperature scales were created to align with naturally occurring phenomena. Specific temperature values are a rather arbitrary definition as the change (or difference) in temperature is significantly more meaningful than a singular value (with the exception of absolute zero on the Kelvin scale). ",
"For the... | [
"Melting point and boiling point are not the only methods to determine purity, and weren't the only ones back in the day either. So you determine the purity of your sample by various methods, if you are sure it is pure, you measure your reference temperatures."
] | [
"Get a pure substance, test it. There are other techniques that you can use to prove a substance is pure (ie chromatography). Note that melting point comparison is only useful when you know that the crystal structure is the same.",
"Take a thermometer without markings. Mark the temperature where water freezes, la... |
[
"How high can a wall made of stone be? Would the wall in GoT be possible?"
] | [
false
] | In Game of Thrones / A Song Of Ice And Fire there is a wall which is supposed to be roughly 700 feet high and 300 miles long. Is this physically possible, or would the stones at the bottom get crushed by the weight? It is also mentioned that the wall is not entirely made of stone, also of ice in some parts, which ration is never really said (at least I never saw it). Would appreciate an answer, thanks! EDIT: Thanks for the answers, just to clear the question up: how tall could a manmade structure built of stone, not of ice and magic, be built? | [
"Ok, assumption time... Wall of stone... Lets pick granite its a nice strong stone since we are trying to build the maximum height.",
"We're also going to assume that we'll be starting construction right on the bedrock which will also be granite for simplicity.",
"Granite has a density of around 0.1 lb per cubi... | [
"The wall is made of ice. It was constructed using manpower and magic. It is this ratio that is never expanded upon or described. This would effectively make the wall a giant glacier that spans the continent since it exceeds 0.1 km",
" of surface area and 50m of thickness. Glaciers ",
" because their massive... | [
"There are granite walls thousands of feet high.",
"Trango tower",
" is about 6000ft.",
"Granite has unconfined compressive strength of about 200MPa and density of 2.75 which means you can make a vertical wall of 7200m before granite will get crushed.",
"If it's made of ice of 6MPa compressive strength the... |
[
"Is there a common ancestor between exoskeleton and endoskeleton species?"
] | [
false
] | There has to be a common ancestor somewhere, but I must not be thinking of the right search terms. I was just thinking about it because endo and exo skeletons are so incredibly different when it comes to how the body is built, so I naturally started wondering where both the frameworks came from. | [
"So the split between lineages with exoskeletons versus endoskeletons happened after the evolution of the coelom (the body cavity). Of coelomates, organisms are either proteostomes (molluscs, annelid worms, and arthropods) or deuterostomes (echinoderms and vertebrates). Endoskeletons evolved with deuterostomes, so ... | [
"This is a long answer. Every line indicates a stopping point, but if you want to understand the answer completely, read to the end!",
"The reason you're having difficulty imagining the common ancestor is probably that you're trying to imagine one that had a sort of in-between of an endoskeleton and an exoskeleto... | [
"Actually, the development of the coelom was recently found to be absolutely useless for determining evolutionary relationships, as discovered by molecular data.",
"http://en.wikipedia.org/wiki/Coelom#Biology_and_zoology"
] |
[
"Reports are coming out that SARS-CoV-2 has been detected in old sewage samples. How many people need to be infected before we can detect viruses in sewage?"
] | [
false
] | The latest report says Spain has detected the virus in a sample from March 2019. Assuming the report is correct, there should have been very few infected people since it was not identified at hospitals at that time. I guess there are two parts to the question. How much sewage sampling are countries doing, and how sensitive are the tests? Lets assume they didn't just get lucky, and the prevalence in the population was such that we expect that they will find it. | [
"The Scottish Enviromental Protection Agency has started testing waste effluent for traces of RNA of the virus",
"Not sure how they are back dating this method but they are using it to test for virus within the population to see how the virus is spreading and where it is within the population ",
"https://media... | [
"Here in the Netherlands they do this. They've been doing it for all kinds of diseases like polio and anti-biotic resistant bacteria and now they also monitor Corona.",
"Info (in Dutch) from our health institute: ",
"https://www.rivm.nl/coronavirus-covid-19/onderzoek/rioolwater",
" The article says they measu... | [
"I'm a molecular biologist, and things like RT-PCR tests for viruses are notoriously tricky and prone to false positives (and false negatives). The nature of how they work (they amplify nucleic acids using short pieces of matching DNA) means that it can be EXTREMELY sensitive. We're talking just a molecule or two ... |
[
"What actually MAKES the ocean salty, but inland water is not salty?"
] | [
false
] | Had a random shower thought about this. What makes the ocean salty? What originally made it salty when the oceans were formed? Was it always salty? If its minerals getting absorbed by the seabed, why is it salty but inland water is not? | [
"Inland water has drainage; the buildup of salt gets washed into the oceans by relatively fresh water. The only way water leaves the ocean is by evaporation, which doesn’t take the salt with it.",
"Rinse and repeat to get salt water."
] | [
"No, there are outputs for salts in the ocean. Think of the oceans more as a way-station for the ionic products of continental weathering, rather than as a final destination. ",
"The outputs are in sea spray generated from a choppy sea-surface; the chemical exchanges between seawater and crust within hydrothermal... | [
"Based in this; is the ocean getting perpetually saltier?"
] |
[
"[Biology] Does animal hair lose its potency as an allergen once it has been shed?"
] | [
false
] | null | [
"most people with pet allergies are actually allergic to enzymes in the dogs saliva. So on the dog or off it doesnt really matter the dander and fluff are well laced with whatever level of ani-funk the pet blessed them with. "
] | [
"It's true that the hair itself is harmless and that saliva... isn't, but it's about how one's body responds to different animal proteins. In the case of shedding fur, these are found in the dander i.e. dead skin cells that are attached to or break off of follicles. So it's not about an ani-funk saliva enzyme trans... | [
"I wouldn't say the problem is shedding in general, if anyone allergic to cats or dogs (or really the proteins in their saliva) buried their face in said cat or dog's fur, they'd have a pretty sneezy allergic reaction. But when they're in households that have cats or dogs and their shed fur is everywhere, yes, that... |
[
"How long take for an atom whose electrons have ascended to a higher orbit due to light absorption to go back in a ground state?"
] | [
false
] | I am interested in finding out if there is a document with the time it takes for each atom to go from an excited state to a low-energy one. For example: when hydrogen passes from 1s to 2s it remains in this state for x seconds, etc. I'm a bit confused about this thing, thanks in advance! | [
"if there is a document with the time it takes for each atom to go from an excited state to a low-energy one.",
"It's not that simple.",
"For a two-level atom, if you prepare it in the excited state, the survival probability decays exponentially with time, where the timescale of the exponential is the mean life... | [
"Yes, each level has a half-life, and there's going to be a cascade through multiple levels to go from a general excited state to the ground state."
] | [
"You can average the mean lifetimes of all transitions, weighted by branching ratios, to get an average time from the initial level to the ground state. But that requires all of those half-lives and branching ratios to be known, and it still won't necessarily be representative of any given cascade event."
] |
[
"Since Adderall is a stimulant, why is it used in the treatment of ADHD? Is it not counterproductive?"
] | [
false
] | null | [
"People with ADHD aren't overstimulated, so much as they're under-focused. The effect of adderall and other similar drugs is to increase focus. ",
"Some interesting reading on the topic."
] | [
"It does, a little bit. But the side-effects are large enough to become disagreeable before the primary effect kicks in. Self-medicating with coffee is a common ADHD trait. Nicotine also."
] | [
"So why doesn't caffeine have the same effect?"
] |
[
"[Biology] Would a stun gun be as effective on a 500lb person as it would be on a 100lb person?"
] | [
false
] | Any constant and controlled shock. And would it matter if the extra weight was from fat or muscle? | [
"Source for ",
" of his claims..."
] | [
"It would be different - and it would matter whether or not the extra weight was fat or muscle. ",
"This is also another reason why arming police with tasers is dangerous, since tasering a very skinny elderly person would likely kill them, as opposed to a younger person with healthier heart. I think police tasers... | [
"A modern taser works by a process known as neuromuscular incapacation, which prevents skeletal muscle from firing. ",
"Simpler devices like a cattle prod, or a taser on ",
"'drive' mode",
", simply cause pain (they are classed as \"pain compliance\" devices). These are the types that can be negated by strong... |
[
"AskScience AMA Series: Hi, I'm Dr. Christina Nicolaidis and I'm editor of a brand new peer-reviewed journal called Autism in Adulthood. Ask me anything about the new journal or the ways that people on the autism spectrum can get better health care!"
] | [
false
] | Hi, I'm Dr. Christina Nicolaidis and I'm editor of a brand new peer-reviewed journal called . I teach social work at Portland State University and internal medicine at Oregon Health & Science University in Portland, Oregon. There's a lot of talk about autism in children, but not as much about autism among adults. That's why we just launched this new academic journal. Our goal is to cover the most pressing issues affecting autistic adults, from emerging adulthood to later life. I am particularly excited about including autistic adults in our new journal - as editorial board members, authors, reviewers and readers. As a doctor and a services researcher, my own research is focused on how people on the autism spectrum can get better access to health care services. Many autistic adults don't get the health care they need, resulting in more health problems and shorter life expectancy. Ask me anything about the new journal or the ways that people on the autism spectrum can get better care. We'll be on at 1 p.m. Pacific (4 PM ET, 21 UT), we're looking forward to the session! | [
"So some adult has (presumably) undiagnosed autism. What's the threshold for \"you need to get help\" vs. \"you've gotten this far without assistance, no need get it now\" that you'd recommend?"
] | [
"First, thank you for this AMA. It seems that GenX adults with milder symptoms, more akin to those that used to be deemed Asperger’s before DSM-5, who were left to navigate the world before there was this current awareness, are still somewhat in a no-man’s land due to the fact that they’ve adopted certain behaviora... | [
"How would an adult go about getting diagnosed? Everyone seems to be focused on diagnosing children. "
] |
[
"Is there an upper limit to the amount of energy a photon can have?"
] | [
false
] | Whenever you see an EM spectrum chart, it always ends at gamma rays. Why is this? Are all photons with more than 100 KeV just referred to as gamma rays? | [
"If Lorentz symmetry is not violated, any photon has any energy in the right reference frame, so it can be arbitrarily high. However, interacting with such a photon might cause black holes to form.",
"I don't think that's what you were asking though. X-rays and gamma rays are basically the same thing except x-ray... | [
"Black holes form when you pack enough energy (specifically mass) in a small enough space. A high energy photon by itself does not have mass, but its energy can become mass when its hits other objects. The energy needed to make a black hole this way is huge, and doesn't occur naturally. And the black hole that's cr... | [
"might cause black holes to form\nWould you mind elaborating? I'm really interested"
] |
[
"[Physics] Would a large stack of clean, standard, gold bars in direct contact eventually weld together through diffusion bonding? - at room temperature, no extra energy aside from pressure of the weight of the stack). How long would it take?"
] | [
false
] | My specific question is about the likelihood of stacked gold bars at normal earth temperatures (tombs, caves, storage facilities) to actually fuse together over a long period of time. Has it happened before? And if so, what process explains it? How long would it take? I've heard this claim before. However, I can't find much on specifics. is the only place I can find anyone making a similar claim. It is one of the reasons stacks of gold will have separate pallets or separators between layers: For short term storage they may just be stacked… but leave them too long and the bars fuse together - and when separated may not have proper weight anymore. Potentially useful links: The reason for this unexpected behavior is that when the atoms in contact are all of the same kind, there is no way for the atoms to “know” that they are in different pieces of copper. When there are other atoms, in the oxides and greases and more complicated thin surface layers of contaminants in between, the atoms “know” when they are not on the same part. | [
"\"Clean\" is relative. Every surface exposed to air immediately acquires at least a monolayer of hydrocarbons and (especially for clean gold) sulfur. The unsatisfied bonds at the surface are just too appealing.",
"",
"In a microfabrication context, \"clean\" would mean deposited atom-by-atom in a vacuum chamb... | [
"You're right, and you need only to look at the paper OP links to to see how they got the gold to stick together. The samples of gold used were sputter deposited in an argon atmosphere and then pressed together at varying temperatures, none below 100 Celsius. These are the most favorable conditions you could imagin... | [
"Where are these separation layers?",
"I could imagine layers of a different material for mechanical stability of the stack."
] |
[
"What is happening when one of my ears suddenly goes 'dim'?"
] | [
false
] | null | [
"I recently finished a neurobiology course, and this was covered. From what my professor said, this type of anomaly originates in the area of the brain that processesall of the information your aural nerves send it. It then sorts through information, and what happens is similar to how your vision (and smell) proces... | [
"OP doesn't mention any vertigo at all, which I thought was a primary symptom of Meniere's?"
] | [
"OP doesn't mention any vertigo at all, which I thought was a primary symptom of Meniere's?"
] |
[
"Why is your hunger levels affected when you are depressed specifically going through love lost?"
] | [
false
] | null | [
"But this wouldn't account for people who lose their appetite when they are depressed."
] | [
"Dopamine and appetite kind of go hand and hand. When depressed, your dopamine levels, along with other chemicals/hormones, are reduced. Dopamine can control how much appetite you have, when dopamine is released, it can work down to your stomach and intestines and trigger a hunger sensation. That sensation can m... | [
"This article",
" should be a good read for you"
] |
[
"Why is oxygen the third most common element in the Milky Way?"
] | [
false
] | Wikipedia article claims that oxygen is the second most abundent element in the Milky Way galaxy. Why is this? Why is lithium, being of the atomic number 3, not the third most common? I would guess that it has to do with the mechanics of fusion, but I don't know for sure. | [
"When stars run out of hydrogen they star fusing helium using the triple-alpha process which fuses 3 helium nuclei into one carbon atom. Once carbon is present, it can be fused into oxygen.",
"The next step, fusing oxygen into neon requires a very massive star, so in most stars oxygen builds up and this leads to ... | [
"Basically, the step of fusing He into C is pretty reasonable for a star that is out of H. That C fuses pretty easily with He to form O. However, it's very difficult for that O to be fused into Ne. The result is that the intermediate amounts of C keep being used up, but large amounts of O build up."
] | [
"But wouldn't that result in carbon being more common? Does the fusion into oxygen occur easily and/or rapidly enough that a carbon atom in a dying star is less likely to stay that way than to be fused into oxygen?"
] |
[
"If I give my glasses to somebody with 20-20 vision, is their sight then as bad as mine?"
] | [
false
] | I've always wondered this, because people will put them on and then claim that my vision isn't bad at all. Also, what might cause both eyes to have different prescriptions? | [
"Is the balancing of eye sight really as easy as just adding or subtracting numbers? I know that's how prescriptions are given, but aren't there variations even past the roundness of an eye? Astigmatisms perhaps."
] | [
"Yes, the glasses make your vision more farsighted to corrected for your nearsightedness. If you give them to someone else, it will make their vision more farsighted than it was before. Depending how nearsighted you are (thus, the strength of your prescription), their eyes may just adjust and not notice a differenc... | [
"Remember that your glasses compensate for an irregularity of your eye, and will therefore overcompensate in the eye of somebody with 20-20 vision (instead of -4, they would see as if they had +4, for example).",
"\nYour eyes have a different prescription, because the eyes are not completely the same. For example... |
[
"Would it be possible to isolate the chemical in psychedelics that causes time dilation and make it into a daily pill that will lead people to feel as if they're living two lifetimes?"
] | [
false
] | null | [
"Hi Inquiring_mind001 thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of t... | [
"Chemistry"
] | [
"'Chemistry'"
] |
[
"Does COVID spread differently in humid indoor environments? (Like swimming pools?)"
] | [
false
] | null | [
"There have been several studies done on the topic. Dry air tends to 'float' the virus longer. Moisture helps the virus settle and deposit on surfaces. See Confined spaces and virus stability:",
"https://www.thelancet.com/journals/lancet/article/PIIS2213-2600(20)30245-9/fulltext",
"https://science.sciencemag.or... | [
"Afaik there have been limited in vitro studies suggesting that Covid like many viruses has favored and unfavorable temperature and humidity ranges. It's not clear to me that we really understand what those are in real life situations."
] | [
"Sorry for the late reply: this is incredibly helpful. Thank you!"
] |
[
"Do endothermic organisms have higher entropy or greater entropy production than ectotherms?"
] | [
false
] | I've studied endothermy and ectothermy but I have never seen this topic contextualized in terms of physical entropy, and a preliminary literature search returns no results. I suppose this question is quite interdisciplinary...maybe if I finish Schrödinger will tell me, but I figured I would ask the panel and see if anyone has anything insightful to say. | [
"Entropy production is pretty straightforward. Any spontaneous transfer of heat means that the total entropy is increasing. If we assume the animal is doing no work on the environment, the loss of heat dQ by the animal lowers its entropy by dS",
" >= -dQ/T",
" and raises the entropy of the environment by dS",
... | [
"Under this view, are animals like partially isolated pockets of the Earth that may decrease their own local entropy temporarily, but that act to increase the Earth's total entropy as a whole? ",
"Yes, but that has to be true for any pocket of the world we can draw a box around. Total entropy is going up, even if... | [
"the animal lowers its entropy by dSa >= -dQ/Ta and raises the entropy of the environment by dSe >= dQ/Te",
"Under this view, are animals like partially isolated pockets of the Earth that may decrease their own local entropy temporarily, but that act to increase the Earth's total entropy as a whole? Particularly ... |
[
"Found in an old post: \"You know if we breed goats selecting for horn distance, in a few generations we should be able to make UNICORNS!\" Is it realistic?"
] | [
false
] | even if not relevant at all | [
"Except that a goat is not a horse."
] | [
"This Image",
" strongly suggests that the basic principal is valid. You can see two horns about halfway merged in the center of the head."
] | [
"Unicorns have a single horn. Goats have two horns. There are other problems. If you listen to Pliny the unicorn was ",
"a creature with a horse's body, deer's head, elephant's feet, lion's tail, and one black horn two cubits long projecting from its forehead",
"You're not going to get that from selective br... |
[
"Do sound waves fall?"
] | [
false
] | Many years ago I saw a primitive sound propagation simulation in which the sound waves fell. I do not know if this was a flaw in the simulation software (physics undergraduate project) or the actual behavior of sound waves. (Also, I would expect that sound moving faster through lower denser air would "lens" the sound upwards somewhat.) | [
"Fell, as in curved downwards due to gravity? No, that doesn't happen unless the medium through which the sound is moving is falling. For example, if there were a vertical shaft with air blowing downwards through it, sound waves traveling horizontally would be deflected downward by the wind.",
"If there is no s... | [
"The density of air decreases as you go up, so if the speed of sound was greater further up, the sound would bend ",
", which could be what was being simulated. Think of it like a light beam going from a higher to lower refractive index, it bends away from the normal, not towards it. In reality though, the speed ... | [
"This may sound crazy but I think sound waves in air fall, because the gas molecules do fall between collisions; but I suspect sound waves in water would not fall. This is what seems intuitive to me but I've been wrong plenty."
] |
[
"Is the speed of a particle and the gravity field it creates related?"
] | [
false
] | My understanding is that you can not accelerate a mass to the speed of light because it's mass increases as it's speed does, and as you approach the speed of light the mass becomes infinitely large, requiring infinitely more energy to push it faster. If this is the case, does a particle moving near the speed of light create a larger gravitation effect that it would otherwise? Such as in the in the LHC where protons are accelerated to c-3m/s? | [
"My understanding is that you can not accelerate a mass to the speed of light because it's mass increases as it's speed does",
"I'm sure that RRC will be along shortly to disabuse you of that notion. I'm layman enough that I can't fully explain why that's the case other than that velocity is not actually linearl... | [
"Well my work here is done. ;-)"
] | [
"As AnteChronos said very well, your premise is flawed. There is no such thing as relativistic mass.",
"What's more, mass isn't the source of gravitation anyway. Energy is ",
" of the source of gravitation, and mass is one type of energy, so while there is a relationship there, it's an indirect one."
] |
[
"Does a car's wheel have rotational velocity?"
] | [
false
] | There's an old riddle about the bottom of a car's tire never moving, but does it have rotational velocity because the rest of the wheel is rotating at a certain speed? | [
"The bottom of the wheel isn't moving relative to the road, but it is definitely moving relative to the axis. "
] | [
"That's not true. OP's scenario is a classic example of rolling without sliding. "
] | [
"The idea is that the bottom of the tire won't move relative to the road, because all the road ever experiences is a rectangle of tire touching it. as the tire rotates, it's indistinguishable from a sliding rectangle (from the perspective of the pavement)"
] |
[
"Does urine have disinfecting properties?"
] | [
false
] | My grandfather told me that when he was a kid and had a small injury he would piss on his wound to "clean" it. Every kid used to do the same. Does urine have antiseptic properties? Isn't this practice dangerous? I mean aren't there any harmful bacteria that could cause something serious? | [
"I can't comment on the use of urine as a disinfectant. I can comment on how urine prevents bacteria growth within the body. In general urea plays a key role in preventing bacterial thread along with pH and fluid concentration. Generally, bacteria with complex nutritional requirements won't grow in urine but it has... | [
"I'm a med student and after reading your comment I was thinking: what about the bacteria that colonize the human urethra? this would potentially contaminate urine and make it more dangerous if it was to be used to irrigate a dirty wound..."
] | [
"I'm a med student and after reading your comment I was thinking: what about the bacteria that colonize the human urethra? this would potentially contaminate urine and make it more dangerous if it was to be used to irrigate a dirty wound..."
] |
[
"Are rapid changes in volume worse for my ears than constantly loud noise?"
] | [
false
] | If I am walking near a highway my ipod volume sometimes gets turned up to near maximum but the volume feels fine (I know that's bad for my ears, but sometimes happens). If later in the day I turn the music back on when working in a quiet area, the sensation in my ears is almost painful. Does this pain reflect some sort of damage? Is it worse to go from quiet to loud immediately vs slowly increasing the volume. Does loud background noise somehow make the loud headphones less damaging to my ears? | [
"Your auditory system can compensate (to some extent) in (quiet or) loud environments. For example, muscles which connect to the middle ear bones can tighten, reducing the intensity level of sound transmission to the inner ear. Additionally, nerve fibers which transmit from the brain to the inner ear can tone dow... | [
"Not an expert, but my understanding is that yes, sudden changes in volume are more problematic. I'm not sure about long term damage, so I won't comment on that.",
"There are tiny muscles in your ear, mostly the ",
"stapedius",
" and the ",
"tensor tympani",
", that tighten in order to dampen the vibratio... | [
"Thanks. i had no idea that there were structural changes to the ear during increased volume."
] |
[
"What exactly causes spaceships to burn in the Earth's atmosphere during reentry?"
] | [
false
] | null | [
"Friction due to the vehicle's velocity.",
"It's not friction. It is due to adiabatic heating from compression of the air. When the object moves through the air that fast, the air in front of it doesn't have time to move out of the way, so it becomes compressed very quickly. This compression heats the air by a la... | [
"Friction due to the vehicle's velocity.",
"It's not friction. It is due to adiabatic heating from compression of the air. When the object moves through the air that fast, the air in front of it doesn't have time to move out of the way, so it becomes compressed very quickly. This compression heats the air by a la... | [
"A re-entering spaceship will be moving very, very fast: even re-entering from low orbit is done at about 8 km/s (17900 mph, or 28800 km/h).",
"Furthermore, spaceship heatshields are usually not very aerodynamic for obvious reasons: you want to lose as much speed as possible while descending.",
"Because of this... |
[
"Is there a proven way to prevent chapped lips?"
] | [
false
] | The title says it all...is there a scientifically proven way to prevent (not treat) chapped lips? | [
"Well it depends on why they are becoming chapped. For example if you are going to become dehydrated/malnourished you should drink some water/eat something before becoming so and if you are planning on sailing accross the carribean in a raft sunscreen would be a good idea (yes on your lips).",
"As for the most c... | [
"Chapping is caused by dehydration, which cold weather tends to exacerbate. Covering the lips with some sort of water-impermeable barrier retards the dehydration. Most lip balms are basically either some sort of wax or petroleum jelly, maybe with some moisturizers and flavoring mixed in. Anything that can create a ... | [
"Anecdotal evidence only, but don't lick you lips, and dry them when they get wet."
] |
[
"Is it possible to measure the amount of air displaced by turning on a shower or some other mundane thing that adds matter to a small area?"
] | [
false
] | null | [
"The pressure increases slightly and briefly, before it has a chance to equalize with the outside world, which is does very quickly in a matter of seconds."
] | [
"For example you could turn the shower on for the length of time it stays in the air for (a bit less than a second), and aim the spray in the bucket, and then weight the bucket or otherwise measure the volume of water in it, to determine the volume of air that the water displaces."
] | [
"In more of a general sense though does the air pressure increase? If it’s your shower or your air conditioner or whatever? I think I worded my question badly. When you are introducing matter into a space does the air pressure increase or does the pressure equalize with the outside world through small cracks?"
] |
[
"If both signals travel at the speed of light why is a wireless connection faster than a wired connection."
] | [
false
] | Is it just allocated bandwidth from the wireless connection, signal/noise?? | [
"a wireless connection is not faster than a wired connection.",
"According to the Shannon-Hartley theorem, if C is the channel capacity in bits/sec, B is the channel bandwidth in Hz and S/N is the signal to noise ratio,",
"C = B*log(1+S/N)",
"for connections of equal bandwidth, only the SNR is the determining... | [
"Wired connection doesn't usually travel the speed of light."
] | [
"because electric fields don't travel at the speed of light?"
] |
[
"Why is rocket staging more efficient?"
] | [
false
] | For example, when you release a stage after using up all its fuel to lessen the empty mass. Why is this more efficient than say having one main fuel "compartment" and just burning it all out of what would be the first stage engines? Definitely phrased this question wrong. | [
"The mass of the full fuel tank is mostly fuel but the actual tank has a significant mass too. When you drop a stage you lose the empty fuel tank and thus make your payload lighter and your lifting job easier.",
"There are also savings to be made in engine efficiency, when you are low to the ground it is importan... | [
"By dropping your big heavy high thrust engines and switching to lighter engines further gains can be made.",
"That's correct, but it's only part of the story.",
"The rocket nozzle is cone or bell shaped. As the gases flow outward they expand, decreasing pressure and gaining speed. Obviously the more expanded t... | [
"Hey Kerb!",
"To make it super simple, lets think about it this way: you're making a week-long expedition up the side of a mountain. Its going to be a long, arduous climb, and its going to take a lot out of you. To prepare for the trip, you've packed a ton of food and supplies into a big, sturdy, weather-proof ba... |
[
"How does the body know the relative position of its parts (eg, where you arm is)?"
] | [
false
] | null | [
"The concept is called ",
"proprioception",
". ",
"I'm sure someone will give a more in depth answer, but essentially there are multiple body maps in your brain, and these maps are used in conjunction with your peripheral nervous system in order to determine body position. ",
"For example, proprioceptors ar... | [
"As already mentioned this is called proprioception. To expand a bit on how sensors in the muscles tell you about limb position: The body's sense of its position in space is determined by stretch receptors in the muscles, joints and tendons. Muscle stretch receptors, or muscle spindles, are specialised muscle fibre... | [
"OP is not being very precise in their question, but it seems proprioception is what they are after.",
"It is worth noting, however, that visual cues seem able to overrule whatever information the brain gets from the nervous system in skeletal muscles: see the famous ",
"invisible hand illusion",
"."
] |
[
"What’s magnesium role in the human body?"
] | [
false
] | null | [
"Magnesium is the fourth most adundant mineral in your body and is involved in over 600 cellular reactions, including: ",
"More Details"
] | [
"If you want the most fundamental answer possible: ATP, the \"energy molecule\" of the body, requires a magnesium ion to function. The presence of this ion is so ubiquitous that it rarely is even indicated, but simply understood to be there. Without ATP, cells simply wouldn't function."
] | [
"I'm a molecular biologist studying RNA. We have to include magnesium in our reactions because it coordinates with nucleic acids and helps them fold correctly."
] |
[
"What did the Wow! Signal actually contain?"
] | [
false
] | I'm having trouble understanding this, and what I've read hasn't been very enlightening. If we actually intercepted some sort of signal, what was that signal? Was it a message? How can we call something a signal without having idea of what the signal was? Secondly, what are the actual opinions of the Wow! Signal? Popular culture aside, is the signal actually considered to be nonhuman, or is it regarded by the scientific community to most likely be man made? Thanks! | [
"The Wow! signal didn't actually contain any information. It was simply a narrow-band radio source that varied in intensity over roughly 72 seconds. There are a few reasons why it's of interest:",
"The frequency of the signal occurred almost exactly at what's known as the hydrogen line, which is the resonant freq... | [
"Astronomer here! You are right but with one very important detail that should be emphasized- we do not know if the signal only lasted 72 seconds, or that even the radio signal itself was varying during that time frame. To explain, the radio telescope that saw the Wow! signal detected sources by just seeing what ... | [
"Because there are a lot of people wondering if, geopolitically, it would be the best thing to tell aliens where we are. What if they're hostile?",
"To be clear, we also don't do a lot of consciously sending out other signals for aliens to pick up (",
"with some exceptions",
") and this isn't a huge part of ... |
[
"How much Asteroid mining/extra mass until it has an impact on earth's orbit?"
] | [
false
] | null | [
"It will not have an effect.",
"Because the sun is so much more massive than the Earth, Earth's mass is essentially irrelevant and only the sun's mass matters. The Earth would have to exert a significant tug on the sun in order for its own orbit to change. However, a heavier Earth would affect the moon's orbit. B... | [
"The ",
" mass of all the asteroids is just .0005 times the mass of the Earth. Asteroid mining would produce no significant change in the mass of the Earth."
] | [
"That's a fairly large scale affect, there're also variations due to changes in elevation and sub surface composition"
] |
[
"Question about Pluto's dwarf planet status?"
] | [
false
] | [deleted] | [
"This is not my field. The problem is that Pluto is in the ",
"Kuiper belt",
" a sort of cold belt of junk left over from the early solar system. ",
"When a proto-planet encounters \"junk in its neighborhood\", one of 2 things should happen, either it captures the junk and adds to its own mass, or its gravi... | [
"The reason that Pluto and Neptune don't crash into each other is not because Pluto's orbit is tilted but because they are in a 3:2 orbital resonance."
] | [
"This is a HUGE controversy. When the IAU voted it was the middle of the night after most members went home. Some people believe they did this just so the one planet found by an American would not be a planet. There is some conspiracy theories it is crazy. I know people who say Pluto is a planet. ",
"As for the t... |
[
"Are some of Pluto's moons really ellipse shaped?"
] | [
false
] | [deleted] | [
"They are not ellipse shaped, but they are not spherical either. Objects that aren't big enough for gravity to pull them into spheres have potato-looking shapes. The cutoff is around 200 kilometers radius: ",
"http://quarksandcoffee.com/index.php/2015/10/29/why-are-some-moons-spherical-but-others-are-shaped-like-... | [
"You, for example, are probably not spherical, but if you were the size of Arizona cubed, you probably would be.",
"I dunno, some people are alarming close to spherical at much lower masses... "
] | [
"Mars' moons are not spherical, nor are most of Jupiter's or Saturn's. Neither, for that matter, are most asteroids. ",
"This page",
" on hydrostatic equilibrium gives a few examples of objects that do and don't have spherical (or spheroid) shapes and their relative sizes. (see the Planetary Geology section of... |
[
"Does naturally occurring oil provide any environmental benefit?"
] | [
false
] | If we never extracted oil from the ground, what would happen to that oil over time? Does it provide nutrients to anything? Will it just sit there indefinitely? Does it hurt anything? BTW I in no way want to use any answers to justify oil extraction | [
"If left unextracted, oil would sit in place until it were either squeezed out by tectonic forces (eventually reaching the surface, in theory) or transformed into natural gas due to heating. It's impossible to say when either process will occur, or how long it will take. It won't hurt anything just sitting under th... | [
"There are also some microorganisms that can metabolize it, but this not likely their primary source of energy. "
] | [
"True, but they live relatively close to the surface. They're generally separated from oil by layers of cap rock."
] |
[
"In board sports, why are some people 'regular' footed or 'goofy' footed and why does this have nothing to do with being left or right handed?"
] | [
false
] | null | [
"Here's a good diagram",
" for anyone needing further clarification.",
"Turns out I push mongo (didn't know there was a name for it) and ride regular. I'm right handed so I thought it was always related."
] | [
"That's sort of what I'm asking. "
] | [
"That's sort of what I'm asking. "
] |
[
"Can radio waves be created in nature? And If so, how?"
] | [
false
] | [deleted] | [
"Radio waves are just long wave electromagnetic waves, and are emitted by anything with a temperature (see black body radiation)."
] | [
"Yeah, look up radio telescopes, a lot of what we know about the beginnings of our universe comes from early radio waves."
] | [
"One of the most ubiquitous signals in astronomy is the ",
"hydrogen 21 cm line",
". Since hydrogen is everywhere, we see this line a lot, right in the middle of the radio band (21 cm wavelength = 1.4 GHz frequency)."
] |
[
"Does leg bouncing/twitching really burn hundreds of calories a day?"
] | [
false
] | From reading around it's seems there's a consensus that you do burn a notable amount of calories if you're a leg bouncer, but the range of calories cited seems really wide. How many calories a day or hour do I really burn from my annoying habit? | [
"I don't know, but I have a feeling it's not that much.",
"What I do want to say, however, is that you should make sure both you and the sources you've read know the distinction between calories and Calories. 1 Calorie = 1000 calories, and the Calorie version is what is quoted on food packages and FDA diet recom... | [
"Who's the fucktard that came up with that convention? And why are people not getting a new name for that?",
"It's like saying ",
".",
"Absolutely retarded."
] | [
"Yup. If you're really serious about being fed up with it, though, you can always move abroad and go metric. :)"
] |
[
"Why is there a 100% chance that a 2D random walker will return to its original position but this reduces to 34% in three dimensions?"
] | [
false
] | So I read that a two dimensional random walker will always return to its original position given infinite time, but this decreases more and more in n dimensions. In three dimensions, for example, I read that there is a 34% chance. Why is this? | [
"I'm ",
"paraphrasing an answer from Math Overflow",
" in a way that will make it more accessible. Let's say you have a random walk in d dimensions. What does it look like when you disregard all but one of the dimensions - you see a 1-d random walk! Since you have d dimensions, we can do this kind of thought ex... | [
"What it ",
" means is that if you consider the probability that it will return to the origin within N steps, as N goes to infinity, the probability approaches 100%. Obviously there will be some paths that don't return, but they're unlikely."
] | [
"I think (but I could be wrong) that the shape of the grid is irreverent in this experiment. The reason being that you can overlay a higher resolution square based grid on any other type of 2d grid, and any path taken in that second grid system can be represented in the square based grid system.",
"The pixels on ... |
[
"When someone says that if you were traveling at the speed of life, time would not pass in that reference frame, what does this mean, exactly?"
] | [
false
] | null | [
"Yeah, in the same way that \"in our current understanding of physics\" things fall 'cause of gravity and not because invisible angels push them toward the ground."
] | [
"Okay, first of all, you can't move at the speed of light. Period. No exceptions, no arguments. You simply can't, not ever.",
"But you can choose a set of coordinates that are moving at the speed of light relative to you. That's trivial. Poof. There they are.",
"Once you've chosen such a set of coordinates, you... | [
"So you're saying that trying to make sense of time as we perceive it makes no sense compared to perceiving time at the speed of light? Could you elaborate on this a bit more? what do you mean by \"infinite-momentum\"? Why is it that the distance between any two points (in a straight line) is zero when moving at th... |
[
"Is Coca-Cola as acidic as my teacher says?"
] | [
false
] | He says it has a pH of 2.8, you can dissolve nails, etc. I disagreed with him and showed him a snopes link that said it was false. He completely dismissed it. If it's false can you provide some sources he'll trust? Thanks Edit: Thank you for all the answers! And yes I know I'm a complete dumbass. Snopes is not a good source. | [
"OP asked for the pH of an internationally known beverage (Coca Cola). Although redditors delivered answers, empirical evidence for the stated fact was not provided, nor were peer-reviewed sources cited. Therefore, we set up a simple experiment to answer OP's question.",
"The beverage was obtained in the cafeteri... | [
"Wow great job! Thank you so much."
] | [
"The phosphoric acid and carbonic acid in coca-cola do have low acidic pHs and given enough time will dissolve all sorts of things, most obviously tranishing on pennies and limescale build up on taps, showerheads or toilets ",
"As both acids are weak acids you wouldn't expect them to be especially corrosive unles... |
[
"Where do the nutrients come from when regrowing romaine lettuce from an intact stem?"
] | [
false
] | We've placed an intact stump in just water and the romaine seems to be growing phenomenally well. However, without soil and the chemistry found therein, what aside from sunlight is promoting this growth? Additionally, the water turns yellow - what process causes this? | [
"what aside from sunlight is promoting this growth?",
"The ",
"carbon dioxide in the air",
". That's why with addition to some other nutrient requirement (such as nitrogen and phosphate), you can grow plants hydorponic settings.",
"Furthermore, the lettuce is likely to have quite a bit of nutrient store wit... | [
"Agree completely with zephirum---most of the bulk of a plant comes from either water or carbon dioxide (providing C, H, and O), so it can increase in size substantially from these alone. The plant is redistributing all the other elements (nitrogen, phosphorous, iron, etc) around itself from reserves in the stem a... | [
"Don't forget, that tap water they are using has plenty of dissolved minerals in it for whatever plant structure is not CHON-based molecules."
] |
[
"When archeologists find a fossil millions of years old, how do they determine its age if carbon dating has a limit of ~60,000 years?"
] | [
false
] | null | [
"There are a whole host of different ",
"radiometric",
" techniques that, depending on the decay system and mineral in question, have time ranges which exceed the age of the Earth / solar system. Radiocarbon dating is important for archeology and very specific subsets of geology that are concerned with deposits... | [
"Thank you!"
] | [
"Also, once you’ve narrowed down indicator fossils you can use those to extrapolate new fossils found…..say you find a new fossil, it’s below a layer containing a fossil you know to be 60m in age, you now have a head start in knowing it’s older than 60m….using stratigraphy can get you most of the way without having... |
[
"What are \"cosmic rays\"?"
] | [
false
] | I know space travel is hazardous to astronauts due to long term exposure to "cosmic rays".... but what are they? Are they part of the electro-magnetic spectrum, like gamma rays? Also, I've read that they are difficult to shield against... but an insulating layer of water in a space ship's hull could provide protection... is that true? If so, why water and not another (less bulky) substance? : Thanks, ! | [
"They are highly energetic charged particles which originate outside our solar system. They are primarily protons.",
"When they collide with atomic nuclei in the atmosphere, they produce showers of other particles via nuclear spallation and other high-energy reactions.",
"There are muons traveling through your ... | [
"what are they? Are they part of the electro-magnetic spectrum, like gamma rays?",
"No, they are not part of the electromagnetic spectrum. The term was coined by Pierre Auger when he reached high altitudes in a balloon and detected \"a penetrating radiation\". Today we know they are actually charged particles tra... | [
"The term \"rays\" is misleading, because it does make them seem more like EM radiation, but they're typically massive particles, usually single protons but occasionally whole atomic nuclei.",
"It was an error that was corrected, but the term stuck. "
] |
[
"Why is the water molecule a dipole in the first place?"
] | [
false
] | Yeah, sure, they teach you in high-school chemistry water is polar and that it is one of the reasons it is so amazing. What they don't tell you is . A quick google search says something about . So what? There's TWO molecules, and since two positive charges repel, wouldn't that make the hydrogen atoms push each other to the far end of the oxygen atom, resulting in a symmetrical molecule with no poles? What's the lies-to-children part of molecular bonds they didn't tell us? | [
"Because there are other electrons on the oxygen that aren't shared with the hydrogen, and they repel each other too. ",
"Here's an illustration:",
"http://learnbiochemistry.wordpress.com/category/water-h2o/"
] | [
"Besides just the hydrogen atoms, an oxygen atom in water has two electrons pairs. All four of these want to be as far apart as possible, resulting a a tetrahedron shape in 3D space. ",
"http://en.wikipedia.org/wiki/Tetrahedral_molecular_geometry",
"I'm sure a chemist could explain this better. Also, I was taug... | [
"If you want to know more detail, read about ",
"VSEPR theory",
". It explains why molecules take the shapes that they do. It says that water is will be similar to a tetrahedral structure (2 lone pairs, 2 hydrogens around a central oxygen), but slightly 'bent' because the lone electron pairs space out different... |
[
"[META] - Introducing AskScience Sponsored Content"
] | [
false
] | The mods at AskScience would like to proudly introduce our newest feature: . We believe that with this non-obtrusive , we'll be able to properly motivate the best responses from scientists and encourage the best moderation of our community. Here is the list of the released so far: All posts must adhere to AskScience rules as per usual, though posts that unfairly attack our sponsors' products may be moderated at our discretion. The best comments in each sponsored thread will be compensated (~$100-2000 + reddit gold) at the sponsors' discretion. Moderators will also be compensated to support the extra moderation these threads will receive. Sponsored content will be submitted by and distinguished to make it easy to identify and prevent spammers from introducing sponsored content without going through the official process. Please see . - djimbob 2013-04-01 | [
"I've already learned so much from all of this. I'm really grateful to the mods for allowing this to take place.",
"I can't believe that oil spills, logging, and mining are actually good for the environment. As soon as I get back to the uni, I'm going to confront those silly conservation, evolution, and ecology p... | [
"This is a terrible terrible idea IMO.",
"If AskScience does this I will be unsubscribing.",
"Edit: Apologies for the short off the cuff reply... I was on a tablet when posting this first message... This thread/concept bugged me enough to switch to the laptop to give a real defended reply with reasons which is ... | [
"I am all for this. Finally the truth can be told without liberal Reddit downvoting everything. We need fracking and Monsanto. People don't seem to understand this.",
"note: payments can be made by paypal to ",
"blueboybob@gmail.com"
] |
[
"What happened to all the energy released during Baryogenesis?"
] | [
false
] | [deleted] | [
"Whatever energy existed in the past is still here, it's just been spread out.",
"The universe is expanding, and as it does, the total mass/energy density of the universe declines. There's stars, galaxies, and the CMB. If you sum up all that mass/energy and then run time backwards to a brief moment after the bi... | [
"I actually don't know anything about the stages of the Big Bang or Baryogenesis, but I think the answer is yes.",
"If I'm wrong, I hope someone can correct me."
] | [
"Does that mean that CMB is the radiation rleased during Baryogenesis only very spread out?"
] |
[
"Why is it so hard to remember dreams?"
] | [
false
] | If I just wake up and go about my business, I never remember dreams. The only way I can manage it is to wake up slowly, in darkness, and what I've been dreaming while I slowly wake up. I think I'm making a conscious memory that is keyed to the ones that have been flagged as unconscious/no access. But once I have that key, I can remember quite a bit about the dream, and even other related dreams. | [
"I usually remember about 4-8 dreams per night.",
"You win, sir; that's the most blatant bullshit I've read today."
] | [
"My dreams are vivid, and I remember them all when the alarm goes off. I return directly to them after that first swipe at snooze. \nThis has remained constant for fifty three years regardless of substance abuse or health regimes. I do not know how or why, but I fly, get laid by twins, get crowned king, travel in s... | [
"I kept a dream journal two years ago or so when I started lucid dreaming, and I found out that just deciding that you will try to remember your dreams makes your dream retention better. Two nights after my first dream journal entry, I was suddenly remembering two dreams each night."
] |
[
"Why have dental scientists (is that a thing?) not come up with something better to fix cavities with than metal tools and drills?"
] | [
false
] | It seems to me that using basic metal tools to hack away at the hard tissue of teeth is a slightly barbaric way of dealing with cavities/root canals, etc. Why have we not come up with something better? OR What could be a future alternative? | [
"They have alternatives. My old dentist used to use a ",
"air abrasion",
" tool (the equivalent of sandblasting for teeth) to clear out tooth decay. "
] | [
"Is there a reason that a) He doesn't anymore? and b) It's not more widespread? It seems that there are alternatives, but why are they not more implemented?"
] | [
"Well, the particular dentist I went to retired. I would imagine the reason more dentists don't use it is because it likely requires going back to get mid-career training in order to be able to use it, also the equipment represents an additional capital cost you need to be able to recover in your business. I woul... |
[
"Why is an electrical plug not hot / warm immediately after being unplugged from an outlet?"
] | [
false
] | [deleted] | [
"Electrical plugs ",
" get warm. If you use a high-power appliance you'll notice it - vacuum cleaners, space heaters, etc. "
] | [
"Electrical conductors are designed with enough cross-sectional area so as not to become noticeably warm under normal use.",
"The thicker a conductor is, the lower its electrical resistance. The heat dissipated by a plug can be calculated with I²R. Say the resistance is 0.01 ohms and you put 10 amps through it. ... | [
"I've seen plugs on extension cords that were rated high enough to handle the air conditioner get a little squishy-melty on really hot days. "
] |
[
"What's the difference between a legless lizard and a snake?"
] | [
false
] | They look very similar to me but what is the real difference? | [
"Another difference is that lizards (even legless ones) have earholes in about the place you'd expect. Snakes have no external ears, and they pick up vibrations through the ground. "
] | [
"There are a bunch of differences between the two (skeletal differences, etc.). But one of the most obvious one is the legless lizard can blink (they have \"eye lids\"), while snakes can't (they have a modified scale that covers their eye all the time and have no \"eye lids\"). ",
"EDIT: This is just a general ... | [
"In addition, snakes have broad belly scales, lizards do not. It's harder to tell by just looking, but snakes have very short tails, while lizards have long tails. "
] |
[
"Why does π come in integrals of Gaussian curves ?"
] | [
false
] | All in the title | [
"The function f(x)=e",
" has the amazing property that the value of f(x)f(y)=f(r), where r is the distance that the point (x,y) is from the origin. This is easy enough to see as ",
"Moreover, up to some scaling factors, it is the only nice function whose product depends on the distance from the origin. This mea... | [
"That was awesome. Thank you!"
] | [
"We use do have to use ",
"Fubini's Theorem",
", along with linearity of the integral, to setup it up."
] |
[
"Is a black hole a perfect sphere?"
] | [
false
] | People speak of black holes having a diameter (independent of the diameter of the event horizon). Do they mean that whatever that diameter measures is part of a perfect sphere? Could there be any perturbations on the "surface" of a black hole, the way neutron stars can have "star quakes" that release gamma ray bursts (and I realize that nothing similar on a black hole, were there any such thing, would release any energy to the outside). | [
"Yes and no. The event horizon of a black hole is not a physical object; it is the beginning of the region at which there are no paths leading away from the black hole's singularity. So a non-rotating black hole will have a spherical event horizon.",
"A rotating black hole has an equatorial bulge due to a phenome... | [
"As material nears the center of the disk, it heats up, releasing x-rays. I seem to remember reading that this is usually in the direction perpendicular to the plane of the disk, but I might be wrong",
"Around smaller black holes, the temperature of the inner edge of the accretion disk is high enough that the pea... | [
"Unfortunately, it's hard to talk about the shape of the event horizon since spacetime is quite curved there. Usually when we think about a shape, we think of one in Euclidean 3-space, and we can freely translate and rotate a body without affecting the \"shape\". However, the event horizon is a surface within a cur... |
[
"If the universe is expanding, does that mean that beyond that there is just nothing? Sorry if this is a stupid question I'm not very educated in any of this."
] | [
false
] | null | [
"There isn't any \"beyond\" the universe, because the current consensus is that the universe is infinite. "
] | [
"No, the answer to his question is determined by consensus. "
] | [
"The space between two objects is getting larger. This is irrelevant at small scales, but at galactic scales we see uniform expansion."
] |
[
"I'm a creationist starting to take a more serious look at evolution. What, in your view, is the SINGLE most compelling piece of evidence for inter-species evolution?"
] | [
false
] | null | [
"Evolution stands as a scientific theory because there is ",
" evidence. Identifying a single piece as the \"most compelling\" isn't really feasible, unless you're willing to accept something like the entire fossil record as a single piece of evidence.",
"If you really want to take a serious look at evolution, ... | [
"ribosomal RNA homology.",
"All living things (depending on how you define \"living\") have ribosomes, and all ribosomes the same basic architecture and purpose. Structurally, they are made of a mix of folded RNA and folded protein, although the RNA parts form most of the \"core\" of the complex.",
"Because ev... | [
"Very literal. As far as we know ",
" life on earth shares a common ancestor."
] |
[
"Does a refrigerator cool more efficiently when it is full or empty?"
] | [
false
] | If I have some food in my refrigerator that I am going to throw away, but that does not need to be thrown away urgently due to spoilage -- say, an expired can of beer -- is it more energy efficient to leave the can in the refrigerator until later, or is it more energy efficient to have as much empty space as possible in the refrigerator? Or maybe it makes no difference? Intuitively, I would assume that the refrigerator would be more efficient with a can of beer because the can "retains cold better" -- but I know that we aren't concerned with cold, we are concerned with heat: and it's much easier to change the temperature of air then it is to change the temperature of a solid. So I guess that as long as no heat is entering the refrigerator, it would be more efficient for it to be empty. Is that correct? | [
"Full. ",
"The amount of energy a fridge consumes depends on the temperature difference between where it wants to be and where it is, temp-wise. Leave a fridge closed and once everything is cool you only have to make up for head influx though the well-insulated walls. This is the lowest amount of energy usage ... | [
"If it is full of cold items - then opening the doors briefly means less cold air to escape and be replaced by warm air. But it will take more energy to cool them down in the first place.",
"But when fridge is cold (and assuming fairly air tight) - I suspect it will loose the same amount of energy to the enviro... | [
"expired beer? you're kidding right?"
] |
[
"Hey social scientists, what do the data actually say about guns and crime?"
] | [
false
] | It's often said by gun-control opponents that gun ownership reduces crime, and obviously we can imagine scenarios where we defend our homes from burglars with the aid of our trusty Glock, but gun-control proponents say you're more likely to shoot a member of your household than a burglar. There seem to be reasonable, informed people on both sides of the issue. What's the truth, empirically? Do places where people have more guns experience less crime, and does it look like the former causes the latter? Does the likelihood of an accident dwarf any such effect? is for expert scientific answers, not layman speculation, memes, politics, etc.* | [
"You may have trouble finding good studies with real data. This New York Times article discusses the ways in which the NRA has used its political clout to defund exactly the kind of research you are hoping to find. It's a very chilling article for any scientist to read.",
"http://www.nytimes.com/2011/01/26/us/26g... | [
"All the data I've seen indicates that violent crime is a function of poverty and other social factors more than gun ownership. ",
"Pennsylvania releases gun sales numbers by county, on a yearly basis. \nI'll use two neighboring counties, Philadelphia and Bucks, as an example.",
"Bucks County is suburban (625,0... | [
"There's an ",
"AskSocialScience",
" subreddit, where you might have more luck."
] |
[
"If light has more energy than microwaves (since it has a higher frequency), why do microwaves have a greater heating effect?"
] | [
false
] | null | [
"All the answers I see here do NOT correctly explain how a microwave works!",
"Microwaves do not heat food by directly imparting energy via photon absorption. They work via ",
"dielectric heating",
".",
"Essentially, the microwave field in your microwave oscillates rapidly. The polarized molecules in your f... | [
"Temperature is a measure of the motion of a molecule. Molecules can undergo several types of motion: translation (where the whole molecule moves in one direction), rotation (the whole molecule spins), and vibration (the atoms in the molecule wiggle with respect to the other atoms in the same molecule).",
"The E... | [
"Actually, dielectric heating does involve the absorption of (microwave) photons. The microwave field is a quantized field just like any other, and the water molecules absorb excitations in this field. It is wrong to say \"do not heat food by directly imparting energy via photon absorption\". That is actually preci... |
[
"Which uses less energy. Accelerating down a hill and using momentum to reach the top. Or, accelerating up the hill after you free roll down?"
] | [
false
] | If you are driving a car and encounter a row of hills all exactly the same height and perfectly symmetrical, what is the most fuel effecient way to drive over them? | [
"On a coarse level, ignoring environmental friction, if you never touch the brakes, you would use the same amount of energy no matter how you drove them. Fuel efficiency is lost when you convert kinetic energy into heat. The power needed to overcome rolling resistance is linear with speed, but the power needed to o... | [
"You don't factor in wind resistance. The faster you go, wind resistance creates exponentially more drag. You want to cross the hills with the lowest average speed.",
"\nSee ",
"cheald's comment"
] | [
"Most cars have a fuel cut off that kicks in when you let off the gas (engine braking). This should tip the scales to always let you coast down the hill, then accelerate up. ",
"Specifically, roll down the hill, off throttle with the transmission in the highest gear. This give the least resistance and still us... |
[
"In Relativity Theory, we are told that time is relative and that there is no \"master clock\" for the Universe, and yet it is commonly stated that the Universe is 13.7 billion years old. How can both of these statements be true?"
] | [
false
] | Is it that the Universe is only this old from our perspective, or is that that this dating is a simplification of a more complicated reality? | [
"We defined it to be the age in the reference frame where the CMB is isotropic. "
] | [
"13.7 billion years is the longest amount of time that it's possible for a massive particle to have experienced between the big bang and (here and) now. It's the amount of time the particle will have experienced if the total amount of acceleration and gravitational fields (which general relativity tells us are equi... | [
"Everything about the universe is in some sense defined in a special frame which has us at the centre of the universe because this is all we can observe. "
] |
[
"Why does a light tap on the testicles hurt so much?"
] | [
false
] | [deleted] | [
"Danger Will Robinson!"
] | [
"Oh dear, we are not supposed to laugh in this sub-reddit. "
] | [
"Wouldn't it be because evolutionarily speaking they are the reason for your existence? Therefore the security system evolved to be very sensitive. "
] |
[
"Does a charged particle feel its own field?"
] | [
false
] | Question is in the title, but specifically I'm thinking about effects of velocity fields vs acceleration fields and what effects it has if any? Also for the Lienard Wiechert fields what is the justification that the acceleration part is responsible for radiation? | [
"Since the top comment is incorrect, I feel like I also need to write a wall of text, so please bear with me. I also know that this is still a somewhat controversial issue, since it has been solved not too long ago.",
"Here is also a recording of a lecture on exactly this subject, if you'd rather hear someone tal... | [
"I've done some reading since I posted this and this seems to be a bit of a rabbit hole.",
"\"In a classical sense, if a charged particle felt its own electric field, it would experience a force. This would basically be self-acceleration, where would Newton's third law put the reaction force? It would ultimately ... | [
"I've done some reading since I posted this and this seems to be a bit of a rabbit hole.",
"\"In a classical sense, if a charged particle felt its own electric field, it would experience a force. This would basically be self-acceleration, where would Newton's third law put the reaction force? It would ultimately ... |
[
"What makes the sound of a stomach grumble?"
] | [
false
] | I assume it has something to do with liquids moving and such, but how can it get so loud sometimes? Why do we not hear the same sounds on a full stomach? | [
"It's called borborygmus and it's caused when the muscle contractions in your upper gut push its contents against the walls, sometimes causing pockets of gas or liquid to move and bubble around.",
"It's louder and more common when you're hungry because after your stomach empties, shortly after eating, the srong m... | [
"Not really - your stomach's job is to mash your food into a kind of sludge with a cocktail of horrible chemicals, which it then pushes into the rest of your intestinal tract so the nutrition in it can be extracted.",
"Your stomach is very strong and usually does a good job of packing the sludge quite tightly int... | [
"Well, they are by most standards - they're caustic, quite toxic outside their intended environment, and very smelly. If you ever attend an autopsy, you may find that they're very unpleasant indeed!"
] |
[
"How big of a role does drag play in atmospheric reentry breakup?"
] | [
false
] | | [
"All of it. When an meteorite enters the atmosphere from space, it’s often going several kilometers per second. Drag increases at an exponential rate, with the velocity squared, so an object going ten times the speed has roughly 100 times as much drag. When it hits the atmosphere the drag and pressure created from ... | [
"Yea, that’s pretty much it. Anything that can’t withstand the drag force gets torn off, and objects that can’t stand the heat melt. Anything else falls to the ground and is usually destroyed."
] | [
"Drag increases at an exponential rate, with the velocity squared",
"So... not exponential.",
"Most of the heating is due to compression, not drag."
] |
[
"We have seen successful transplants of various organs, hands, even faces -- so why not transplants of legs or feet to lower-limb amputees? Why are these not a thing?"
] | [
false
] | null | [
"Prosthetics. The lower limbs are simple enough that you can use a fake one and still get around for the most part. They've even got those special legs for running that are banned in the Olympics for being too fast. It's just not worth the risks from transplants. With transplants, you have to take immunosuppressive... | [
"People need to understand that transplants are never actually successful. When someone gets a new kidney/lung/heart the body wholeheartedly rejects it. The recipient has to take immunosuppressant drugs for the rest of their life which does nothing more than slow down the bodies ability to reject the organ. But rej... | [
"Risk of rejection would be the biggest one , not to mention having to suppress your immune system. ",
"And it’s all to get back something very simple and easy to replicate if not provide something that performs even better ",
"Not to mention we already have a small supply of spare organs for transplants , it’s... |
[
"How do we know the core of the Earth is hot?"
] | [
false
] | How do we know its really hot when no one has been to the core of the Earth? I get that there is magma and all, but where is the gaurantee that it's from the core? It could very well be from the mid layer | [
"In addition to the other answers, if you drill down, it gets warmer. There are lots of caveats to this. The deepest hole is about 12 km and the earth is >6000 km is size, so we have only drilled a small percentage of the distance. This does not guarantee that the core is a particular temperature, but any mo... | [
"This is a good question, the answer to which (exactly how hot is the core?) is not precisely known and con't be measured with current technology.",
"However, it is hot by all reckoning (4000K - 7000K). The simplest explanation proceeds from the assertion that the outer core of the earth is liquid FeNi. At the p... | [
"Huh, so it's about as hot as an oven. That's really crazy, as that doesn't SEEM that hot, but I've heard that the heat is what prevents them from continuing further?"
] |
[
"Is it possible to have an object whose surface area grows faster than its volume?"
] | [
false
] | I am familiar with the square-cube law, but all the examples I can find only discuss regular solids, I am wondering if it applies to all 3D objects. | [
"If you mean: an object in regular (euclidean) 3D space, and you are looking for an object whose surface grows faster than its volume, the answer is no. All objects will show cubic scale behavior for the volume, and quadratic scale behavior for the surface, under linear scaling.",
"However, it is possible, for a ... | [
"There is a class of mathematical objects with infinite surface area but finite volume. Take the function 1/x and revolve it around the x axis from x=1 to infinity to give a trumpet shape. The resulting integral is finite, but because the function has an asymptote and never quite reaches the x axis the surface area... | [
"because the function has an asymptote and never quite reaches the x axis the surface area would be infinite.",
"1/x",
" has an asymptote and never quite reaches the x-axis but its integral from 1 to infinity is 1.",
"https://www.wolframalpha.com/input/?i=integral+1%2Fx%5E2+from+1+to+infinity"
] |
[
"Will the first influenza season after all corona restrictions are lifted be worse than before?"
] | [
false
] | It is my understanding that our immune system needs, to some extend, "training" or rather some exposure to germs in everyday life to keep us healthy. To my knowledge, this is also why overuse of desinfectants (e.g. every time you touch something in public spaces) is actually a bad thing. So, I was wondering whether the next influenza season or some other disease could become worse (meaning more people suffer from it or show more severe symptoms) than before because our immune systems won't be up for the task when the corona restrictions are lifted. | [
"This question is complicated on many different levels, but I can explain a few things. First, the state of seasonal influenza is determined by random mutation, but mutation can only occur when the viral genome is replicated during infection. The virus needs host infection to produce more mutations, and this years ... | [
"Thanks for this response. I guess we can only hope that wearing masks will at least somewhat become a new normal when people are feeling sick. Regarding the flu shot: won't this only work in more developed countries because poorer countries don't have enough access to flu vaccines?"
] | [
"It’s complicated. ",
"A recent paper tried modeling the impact of non-pharmaceutical interventions (NPI - things like social distancing and wearing masks) on future influenza and RSV outbreaks. (RSV is respiratory syncytial virus, another seasonal respiratory pathogen.). They concluded that the current downturn ... |
[
"What was the most commonly held scientific theory regarding the origin of the universe and what observation led scientists to question this theory compared to the big bang ?"
] | [
false
] | [deleted] | [
"infinitesimally small at some point",
"Just to nitpick, infinitely dense not infinitely small."
] | [
"infinitesimally small at some point",
"Just to nitpick, infinitely dense not infinitely small."
] | [
"Sort of... More accurately, they used various branches of physics to make predictions about what the universe should look like if the big bang occurred, for example the spectrum of the Cosmic Microwave Background. They found repeatedly that the theory led to accurate predictions and so gradually came to the conclu... |
[
"I am the \"X\" number person to have existed, ever. How would I approximate \"X\", for a given year in time?"
] | [
false
] | null | [
"I can tell you how to do it in a very round-about way as I don't know the exact method (which I think you may be after here, rather than just a way to get \"your number\"), however - have you seen:",
"http://www.bbc.co.uk/news/world-15391515",
" this?",
"It works out from your date of birth what number out o... | [
"That website actually also gives you the number person alive you are aswell when you put in your age and gives this blurb about how the calculate it:",
"\"Both numbers have been calculated using UN Population Division figures. The first is an estimate of how many people were alive on your date of birth. It is on... | [
"Well, first you'd need to decide what constitutes a person for your purposes. Evolution doesn't produce neat little tags on the back of the neck with one's species written on them, and at what age even a modern human may be considered a person is very dependent on your definition."
] |
[
"Are there researchers/academics that need development help from a highly-motivated scientific amateur? Advice on connecting with them?"
] | [
false
] | [deleted] | [
"You could always just cold call/e-mail faculty at a local university in a department you're interested in. Or even go to the department (best to have a meeting there with someone already) and talk to scientists in person. This is what I did when I wanted to do astronomy research in high school. When I found a proj... | [
"going back to school to get a physics degree isn't really an option",
"I'm not sure if you're interested in this or not, but there are other options that could let you avoid doing an undergrad degree. For example, you could simply apply for a phd in bioinformatics or ",
"computation biology",
".",
"Outsid... | [
"Why don't you offer your services in biophysics/molecular biology by means of molecular simulation?\nAdvantages:",
"You can work from home",
"It is at the interface between chemistry, physics and biology",
"All tools are open source (I used ",
"GROMACS",
" which is also well-documented and has a great s... |
[
"Correct me if I'm wrong, it is possible to send a message through light right?"
] | [
false
] | [deleted] | [
"When you turn on the radio, that's what's happening. Radio waves are a part of the electromagnetic spectrum, just with a much longer wavelength than visible light. Visible light isn't all that useful for this sort of thing, because it tends to not go through things..."
] | [
"Again, we already use radio waves for this (communicating with our deep space probes). ",
"Radio waves ",
" are light, just at much lower wavelengths than the light that our eyes are capable of seeing. If you wanted to send a message deep into space using visible light, like the laser you saw in class, you cou... | [
"You mean like radios, cell phones, wireless internet, fiber optic communications...?"
] |
[
"What determines the number of propeller blades a vehicle has?"
] | [
false
] | Some aircrafts have three, while some have seven balded props. Similarly helicopters and submarines also have different number of propellers. | [
"You can imagine an airscrew as a disk that accelerates air passing through it and creates a pressure change across the disk. ",
"https://en.wikipedia.org/wiki/Momentum_theory",
"The average pressure change accross the disk is called ",
"disk loading",
".",
"If you want more thrust, you can either increas... | [
"I just wanted to add that same principles work for water too. For ship propellers and the like. You practically just change the fixed valued for air for water values like weight, viscosity and so on. Even the efficiency principle: infinitely large, slowly moving propeller is the most efficient but in oractice ther... | [
"Water propellers actually have an additional consideration to take into account during design - cavitation.",
"The fluid medium they're in can phase change under certain conditions if the propeller creates momentary areas of low pressure in the fluid as it moves. In practical terms this means bubbles, but the ... |
[
"Would a more massive object fall slightly faster than a less massive object with no air resistance?"
] | [
false
] | I've been taught that without air resistance, any object, when dropped, will fall at the same speed based on earths gravity. However, would a more massive item have a larger gravitational pull of its own, pulling itself towards earth slightly faster than a less massive object? | [
"Surprising fact: no it wouldn't! This is a very special fact about gravity. No other force works this way, and this is one of the things that inspired Einstein to develop general relativity.",
"In algebra terms, here's what's going on. The attractive force between the earth and the object is ",
"Where ",
" i... | [
"When you use the formula you have to have reference point. When dealing with that situation usually use earth as reference point. So earth is stationary. If in your edited scenario earth is also moving then your reference point is outside of earth and formulas are changed."
] | [
"Wait no. I don't think that's right. I can choose a \"lab frame\" independent of the position of both the Earth and the falling object, and the formulae I wrote down would still hold. And thanks to Newton's third law, the Earth has to feel some acceleration due to the pull of the falling object."
] |
[
"[optics] How small can focus spot be?"
] | [
false
] | There is a great post on XKCD about how you cannot focus light to a hotter spot than the source. I kinda understand that, but then again - not quite. Specifically, what limts the size of a focal spot? The smaller the focus spot size, the bigger density of photons and, thus, hotter it is. I cant seem to find information about this. Maybe im just googling wrong. | [
"Geometrically speaking, it can be infinitely small. But the problem begins when you consider the wave property of light: if you do the calculations (which I do not recommend, but it is fun to see it once), you'll see that the remaining pattern will be a sort of wavey-pattern, with a large middle peak. The size of ... | [
"You are looking for ",
"diffraction limit",
". I have not seen xkcd post you are referring to, but my guess is that it was an analogy to a blackbody radiation or second law of thermodynamics that was supposed to help you understand, but in the end did the opposite. It would help if you can link the post here. ... | [
"Call it by name: Diffraction."
] |
[
"Do you think there will be another paradigm shift in science like the emergence of quantum mechanics 100 years ago?"
] | [
false
] | Will there be another incisive paradigm shift at some point, or will it be a more gradual transition. What candidates are there for such a paradigm shift? String theory? A post-quantum theory? How would science/technology change with this paradigm shift? What problems do you think we would be able to solve? On a related note: The common opinion (that may actually be a myth, but that's a separate issue) is that scientists in the late 19th century thought that all problems in science were essentially solved and that any further development would be incremental. Today, we think we have learned our lesson: we know that we don't know everything and that another paradigm shift might occur. Still, I have the feeling that we (the scientific community) secretly believe that we know better today and at least won't be surprised by another paradigm shift. Again, take string theory as an example: do the results of a theory still constitute a paradigm shift if you have been researching this theory for more than 40 years? | [
"Hmm... these are all very nebulous terms that \"philosophers of science\" sometimes like to use... and they're all very nebulous. Most scientists don't really talk about them seriously, in my experience.",
"In a sense, the difference between a sudden paradigm shift and a gradual transition has nothing to do wit... | [
"Edit: Oh shit, I didn't know you were a panelist. I would have written much less, and differently."
] | [
"so? substitute \"small\" for \"weakly interacting\", \"turbulent\", \"really, really far away\", \"Magnetic\" or any number of other tricky conditions."
] |
[
"In the double slit experiment, what are the results if you remove the slits? Does the wave pattern still appear?"
] | [
false
] | null | [
"If you remove the slits, you just have a screen that blocks all light going through. So the result is, no light goes through."
] | [
"You get ",
"single slit diffraction"
] | [
"Ideal interference specifically needs multiple point sources; the pattern washes out as the width of the slits becomes comparable to their separation. In the limit where the widths are half the separation your wall has vanished: nothing fancy happens here, it's the same thing you get if you shine a lightbulb onto ... |
[
"Layman's question on the curvature of spacetime"
] | [
false
] | Let's assume I'm stood on the surface of an Earth-like planet in the depths of space, it is stationary (not orbiting anything or rotating). I jump into the air, with my legs, at non-relativistic speeds. According to Newton, I exert a force against the ground greater than the force of gravity, this propels me into the air until the force of gravity pulls me back to the ground. The more force I exert, the higher I jump. No problems understanding this. According Einstein, gravity is not a force. I exert a force against the ground which pushes me in a straight line through curved spacetime, the curvature depends on the mass of the planet. This sounds reasonable, but I can't wrap my head around what exactly determines how high I jump. If I was just moving faster in the same direction then wouldn't I just jump and land rather than higher? Is it that the direction away from the mass is more difficult to travel through, and if so, how is this not a force? If I jump directly up with varying forces at different times, I am landing in the same place but travelling to it along many different up-down directions, all of which are straight lines. So are there a continuum of different "ups" depending on how much force I exert, or am I missing something? I'm guessing my problem in understanding this is due to me being unable to visualise the relationship between position and direction in a 3D curved space. Can help? | [
"One of the key ideas that allowed Einstein to unlock general relativity is known as the equivalence principle.",
"Imagine you go to sleep tonight, and wake up sometime later in a room with no windows. This room just happens — because you're lucky, and also this is all imaginary — to be stocked with every piece o... | [
"If gravity relies on a constant acceleration, what happens when velocity reaches the speed of light?",
"It doesn't. Nothing can ever go that fast.",
"Does this mean you could accelerate forever at a constant rate?",
"Yes!",
"Imagine we're sitting here on Earth, and there's a spaceship on the launch pad. Th... | [
"At the risk of sounding stupid, does equivalence mean that a mass at rest has intrinsic acceleration which is equivalent to a change in velocity?",
"A mass ",
" that's at rest ",
" is undergoing acceleration, yes.",
"At this level what we mean by \"acceleration\" gets a bit wonky, because we normally think... |
[
"When Deuterium and Anti-Hydrogen Annihilate, What Happens to the Extra Neutron?"
] | [
false
] | According to Star Trek lore, Federation starships are powered by matter-antimatter reactions, but more specifically, this reaction is canonically said to be between deuterium and anti-hydrogen. Given that every atom of deuterium has a neutron in it that hydrogen (and anti-hydrogen) atoms lack, what would happen to this neutron in real life if an atom of deuterium were to annihilate with an atom of anti-hydrogen? | [
"Antiprotons (the nuclei of antihydrogen) will happily react with both protons and neutrons - they don't care. And as both of them are close together, the reaction is really more like \"deuterium nucleus+antiproton -> X\" where X will typically contain either a proton or a neutron (with about 50% probability) and a... | [
"I see, thank you. So roughly half the time we’re left with a proton and the other half of the time, we’re left with a neutron? In either case, we are left with one baryon (if I have my terminology right)? Plus a pion or few, as you said. Am I correct in understanding that the fate of this leftover baryon depends o... | [
"Yes."
] |
[
"How do I do research on my own? (sonoluminescene)"
] | [
false
] | null | [
"Start by reading up on bubble dynamics, for example, the Rayleigh-Plesset equation. Tim Leighton has a book on it, called The Acoustic Bubble, that may interest you. You'll need to know differential equations.",
"The rate at which surrounding water fills the bubble was largely worked out by Rayleigh in 1917."
] | [
"The book is so much money :(",
"124 dollars for a paperback edition. I may have to pirate it :X"
] | [
"Oh no!",
"Also, try to read through as many sonoluminescence papers as possible. That's how you stay on top of a topic."
] |
[
"It is estimated that at formation the moon was between 20 to 30 thousand kilometers away from earth. With the moon's closer proximity, how often would earth experience solar eclipses, and what effects would it have on the path of totality?"
] | [
false
] | null | [
"I'll have to check my math again tomorrow but it seems as though almost every single new moon should be a full eclipse. At a distance of 20 thousands km only a 93 km radius circle is needed to completely cover the Sun. And even though the Moon's orbital inclination will carry it above and below the line of sight t... | [
"Thank you for the answer."
] | [
"The length of the totality would depend on the rotation rate of the Earth. What did you use for your estimate?"
] |
[
"Have any animals shown signs of reaction to music? Or any studies to suggest they can feel appreciation to or at least recognition of it?"
] | [
false
] | null | [
"National Geographic seems to think so on some level:",
"http://news.nationalgeographic.com/news/2001/01/0105biomusic.html"
] | [
"Discriminative and reinforcing stimulus properties of music for rats",
":",
"We trained rats to discriminate music by Bach from that by Stravinsky using operant conditioning. The rats successfully learned the discrimination and transferred their discrimination to novel music by the same artists. Then, we train... | [
"Quite a few I think. I specifically remember dairy cattle being shown to react to music being played whilst being milked; they produced more milk when classical music was played compared to rock and roll. A quick google found ",
"this",
"\n and ",
"this paper",
" about chickens"
] |
[
"What temperature would be required to ignite the earth's atmosphere, and would it be possible for humans to ignite our atmosphere?"
] | [
false
] | null | [
"The possibility of humans igniting the atmosphere was considered as part of the initial work on the development of the atomic bomb.",
"The fear was that if you set off a fission bomb, then you could release enough energy to cause fusion to occur in the atmosphere. These fusion reactions would release more energy... | [
"Technically at 2000℃, carbon dioxide decomposes into carbon monoxide, which is flammable at 605℃, and may at the right mixture explode (12,5%-74,2% vol), meaning it would be possible if you manage to hear up the entire atmosphere a LOT.",
"Dust explosions are like saying 'lets just add a flammable gas and light ... | [
"Sorry if I'm off on this, but if you're igniting carbon monoxide won't that just get you back carbon dioxide? The opposite process of CO2 decomposing. "
] |
[
"Could an animal come back from extinction due to evolving?"
] | [
false
] | There's been a post circulating reddit that says about a bird coming back from extinction die to evolution which has been said is fake but I'm wondering could it be possible that animals couple evolve back an extinct species (say the dodo for example) | [
"What this story is about is ",
"this paper",
". The study basically found that there was a bird (let's call them bird 1). Some of the population of bird 1 flew to a new island where evolution made them lose their ability of flight, turning into a new species of bird (bird 2). Their new island then gets flooded... | [
"A species could evolve to resemble a species that went extinct. See: ",
"convergent evolution",
".",
"But they would not be categorized as the same species. And to say that the animal \"came back from extinction\" is sensationalism."
] | [
"I like how much this suggests about the kinds of factors that influence evolution. In this case, it's almost a deterministic: similar inputs (bird 1 + island 1, bird 1 descendant + island 1) yield similar outputs."
] |
[
"I am an artificially-intelligent machine. What do I need to do to prove it?"
] | [
false
] | null | [
"what does it mean to be artificial?"
] | [
"The politically correct term is \"synthetic sentience\". "
] | [
"Have a conversation with a person to the point that the person with whom you are speaking does not realize you are not human.",
"Or in a less round-a-bout way of saying it; take you, put a real person next to you, and have a person talk to you both without being able to see you. If the person is unable to identi... |
[
"Does a sickness know when it is losing the battle in its host (i.e. when the host starts getting better)? If so, does the sickness try to do anything differently to try and stay alive?"
] | [
false
] | null | [
"Wow, ok, good question. \nSo if you’re thinking about “foreign invaders” I think not. I mean bacteria, viruses and parasites don’t really have a super complex thought process. They are driven by basic needs: to survive, to procreate. So I don’t think they “know” per se they are losing the battle. \nThat said, bact... | [
"bacteria for example mutate under certain conditions (eg. inhospitable environment) and create resistant genes in order to survive better against the attackers (antibiotics)",
"Mutations don't happen in response to treatment. They are generally random. Sometimes a random mutation produces a result that makes the... | [
"You are partially right. ",
"Mutations do happen indeed because of randomness, but they also happen in response to treatment. And it happens so darn fast, because bacteria can just \"touch\" each other in order to share information aka resistant genes. ",
"I would refer you to this comprehensive article which ... |
[
"Does the road heat up due to friction?"
] | [
false
] | I know that just one car driving on a road won't be enough to cause any heat change. However, I was wondering if on a highway early in the morning, let's say 05:00 am, where the ambient temperature of the air is 5 C would the friction from the morning traffic traveling at 120 km/h cause the road to eventually heat up significantly? Because I know that tires do get quite hot from the temperature from the brakes as well as the actual friction to the road. Would that same friction cause the road to heat up or does the heat disperse into the earth fast enough that it is a negligible difference. | [
"Why does snow seem to melt more and wet road seems to dry sooner where car tires pass vs where they don't?"
] | [
"A rolling (not slipping) rigid wheel will not generate any heat from friction of the surface of the wheel against the surface of the road. Work requires relative displacement of the two surfaces, not just a force. Static friction theoretically does not do work. e.g.: doing a burnout will create heat",
"That heat... | [
"That's because of pressure as already answered, and it's also because of the contact in wet conditions as the water gets a larger surface area and relative wind speed to dry to."
] |
[
"Black holes?"
] | [
false
] | I was just reading an article about how there are high resolution photos of a super massive black hole ( ) and I started thinking. 1) Are black holes stationary (i.e. do they orbit other things, or do they sort of float around in space and time)? 2) If they are stationary, what would happen if two black holes encountered each other? Would they combine into an even bigger black hole? I'm not a scientist, but these sorts of things are really interesting. Thanks! | [
"A collision of black holes would be very dramatic and exciting event.",
"To steal from my ",
"own post",
" in another thread about a month ago:",
"When two black holes collide, they coalesce into a single black hole. And, if all goes right, ",
"LIGO",
" and ",
"VIRGO",
" detect the events (and may... | [
"Black holes can merge, yes. I'm just not sufficiently knowledgeable to explain the repercussions of it. "
] | [
"Thank you so much!"
] |
[
"Do small dogs have less mental capacity than larger ones?"
] | [
false
] | [deleted] | [
"Attempts to measure the differing intelligence of different breeds have been made (",
"see here",
"). At a fairly casual glance it is difficult to see any correlation between average size and intelligence. Certainly there is no strict relationship, as demonstrated by Miniature Schnauzer (weight 5-8kg) at 12t... | [
"Thanks for the link. "
] | [
"To truly determine if this correlation is true would require quite a sophisticated analysis that requires the incorporation of phylogenetic information (the evolutionary history of dogs)"
] |
[
"If a fly, the insect, flies into a car and the car moves, would the fly stay stationary where it is in the car or would it be pushed to the back of the car?"
] | [
false
] | Usually when you're in a moving car you get slightly pushed to the back. Would a fly be pushed as well? | [
"When a car accelerates forward you are not pushed back in the car; the car moves forward and pushes at your back. Since the air inside the car is moved along with the car, when the car is accelerating the rear of the car will move toward the fly, but only slightly."
] | [
"You can consider a fly in your car similar to a fish in a bowl of water. The air in the car is a fluid like water, but less viscous. Since a fly is a lot lighter than a fish, it's still enough to carry the fly around as you accelerate the car."
] | [
"Yes, it will. In fact, assuming the fly just hovers there, it would smack the back of the car, here's why:",
"Here's a ",
"graph",
" of the fly in your car as you accelerate from a stop to 108 kph (~67 MPH). Note that the \"fly displacement\" is BACKWARDS towards the rear of your car. I can provide the equat... |
[
"Why do we use different units for the same thing?"
] | [
false
] | Hey guys. In Richard Feynman's book The Character of Physical Law he says that if you want to embarrass a physicist, ask them why they use different units to measure different kinds of energy when they could use one for all energy and make it less confusing, since energy is everything. Do you actually think this would make the subject less complicated, and if so, why don't we do this? Thank you for any insight. | [
"I do not think using one unit of energy would necessarily simplify the matter (sorry for the pun). Sometimes, using a specific unit of energy allows one to quickly gauge the relative energy of the system one is investigating. ",
"For example, consider the unit of electron volts, which is equal to the energy chan... | [
"Could you clarify what different kinds of energy he means. If he means kinetic or thermal etc then I don't agree that we do. Sure different physicists might use ergs vs joules or whatever but they don't usually use different units between forms.",
"If he means mass and energy then well part is tradition part is ... | [
"The order of magnitude is also convenient, since there are not excessive digits or decimal places.",
"I can not stress this point enough. Sure we could work in all the same units, but when it comes to using computers for data analysis and modeling, different unit systems are beneficial for preventing numerical e... |
[
"If I mix red and blue paint, do the two colours ever truly become one? Or if I zoom in close enough, will I always see distinct red and blue particles?"
] | [
false
] | null | [
"The pigment molecules stay exactly the same. You see a mixture of red and blue light that your brain perceives as purple. "
] | [
"It's possible to design pigments that have any colour of the visible light spectrum. (any colour of the rainbow in other words). However because of the huge range of coloured paints I suspect many of these aren't pure solutions of pigment but rather mixtures of different pigments.\nSo your purple paint may either ... | [
"It's possible to design pigments that have any colour of the visible light spectrum. (any colour of the rainbow in other words). However because of the huge range of coloured paints I suspect many of these aren't pure solutions of pigment but rather mixtures of different pigments.\nSo your purple paint may either ... |
[
"What are the the fundamentals and differences of different types of bonding? Are some bonds the same as other? What are the pros and cons of each bond?"
] | [
false
] | null | [
"The question is asking a lot. We request that you do some research on your own before posing a question, and that should answer several of the points you are asking. But there is a continuum between ionic and covalent bonding, which relates to the degree that electrons are shared between bound nuclei. In complete ... | [
"For simplicity, you see more ionic character in bonds when there is a greater difference in electronegativity between the bonding atoms. So, when you have an alkali metal or alkaline earth metal bound to a halogen or oxygen, then it will be ionic. But when there is a small difference in electronegativity, like bet... | [
"I am not sure how you come to the conclusion that ionic bonds are stronger than covalent bonds. Covalents bonds with a partial ionic character are stronger than totally covalent bonds as far as I know.\nDid you derive this (covalent bonds weaker than ionic bonds) from the Gibbs free energies of formation? And if s... |
[
"What would happen if Earth moved at a different speed in its orbit around the sun?"
] | [
false
] | At this moment it's orbiting at about 30 km/sec. What would happen if the earth would, for instance, orbit at 20 km/sec around the sun? Or at 40 km/sec? | [
"I don't really understand your question so I'll try two interpretations",
"Interpretation 1: The earth suddenly loses (gains) speed from one moment to the other with everything else staying as it is. Not taking into account effects due to the acceleration, the earth would go from the basically circular orbit, it... | [
"The orbit would become elliptical with endpoints lying on the original circular axis. Our orbit would turn into a oval that gets close to the sun."
] | [
"Wait, you say that it would heat up the Earth, but the world would still spin around its shoulder, and the Earth would lean the same way, anyway. Isn't this, in fact, a completely moot question? Wouldn't the only differnce be that a year is longer?"
] |
[
"Why doesn't the roche limit have an effect on objects like the ISS or people when we orbit the Earth or Moon?"
] | [
false
] | This may not be the most accurate way to describe it, but I have been told that objects get ripped apart by the roche limit because they get too close to another object and the gravity from the bigger object rips them apart because their mass doesn't have enough gravity to hold itself together. Given we are much smaller and have way less gravity, why don't we get ripped apart in orbit? | [
"The normal roche limit is based on something with 0 tensile strength / is purely held together by gravity. This is a good approximation for a planet or large moon, but not for a person or manmade object. (If it were, we'd all be spheres)"
] | [
"The Roche limit applies to bodies with enough mass to be held together by their own gravity. The ISS is obviously held together with welds, nuts & bolts. It doesn't have any gravity to speak of. So the Roche limit does not apply."
] | [
"\"In celestial mechanics, the Roche limit, also called Roche radius, is the distance from a celestial body within which a second celestial body, ",
" will disintegrate because the first body's tidal forces exceed the second body's gravitational self-attraction.\"",
"If indeed the ISS or people were merely bein... |
[
"Are our brain's wrinkles unique to each individual like fingerprints or are they mostly the same shape with few variations?"
] | [
false
] | null | [
"They are generally the same in a gross manner. For example most people (~70%) have a ",
"lateral occipital sulcus",
" but not everyone does.",
"You may find people completely lacking a sulcus (groove) or gyrus (ridge) where others may have one more than a \"regular\" brain.",
"Anatomical textbooks generall... | [
"And what are the changes associated with those variations? In case we know."
] | [
"Are you trying to describe neuroplasticity?"
] |
[
"Best Carl Sagan Book?"
] | [
false
] | I am looking to pick up my first Carl Sagan book and since I trust the Reddit Science community more than random internet threads I thought I'd ask; Which is the best Carl Sagan book and why? | [
"I thought Contact was amazing."
] | [
"Second vote for demon haunted world. Really the first book of it's kind: A broad overview of pseudo science."
] | [
"Also, do watch all 13 episodes of COSMOS: ",
"http://hulu.com/COSMOS"
] |
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