title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"If you could take a representative section of the sun and instantly move it off by itself, what would happen to it?"
] | [
false
] | Say you could snatch away say, 5% of the sun by mass that was proportionately identical to the sun; then plop it down in an area of space that's minimally affected by any external gravitational forces. Would it just become a tiny star just like the sun? Supernova or collapse on itself? | [
"If its small enough, the outward forces would blow it apart and you'd get a fairly impressive explosion, though most of the matter involved would simply be scattered across space instead of being converted into energy, so it wouldn't be on the scale of a supernova or anything. If the section is large enough that t... | [
"Not when it's just 5% the mass of our Sun. The gravity would be too weak."
] | [
"If what OP is saying is that this would be a copy of the sun with all the properties kept the same but just 5% of the mass/size, then this object would be at MUCH higher temperatures and pressures than any object of it's size would every naturally be at. That means it will definitely \"explode\". How spectacular a... |
[
"Why is it that, in any other country, extremely heavy rain is frequently accompanied by lightning, but here in Ireland, we get, max, 2 or 3 storms a year?"
] | [
false
] | I love lightening. I live in Ireland. We get torrential downpours of rain, daily. Frequently they are epic, wind-driven, biblical sideways rain (at least where I live, in a very exposed rural location). Yet we almost never get so much as a thunder storm. Actual fork lightening, you know, the exciting kind, comes only a handful of times a decade. I was in Germany recently, and there were 8 lightening storms, with real forkers, in 5 days. As a lightening fan, I feel hard-done-by. Ireland's weather sucks. So, AskScience, WHAT GIVES?! | [
"You need warm, humid air to be pushed into extremely high altitudes, so that the moisture can turn into ice and start building a charge. Ireland doesn't have warm humid air."
] | [
"Not just turn to ice; you need the droplets to become supercooled (remain liquid at temperatures below freezing) so that they can form an ice crystal/water mix that collides with other ice crystals.",
"This is also why you very rarely see lightning behind snow. The moist, but cold, air masses which cause snow ne... | [
"Your weather and that of the UK and a lot of western Europe is mostly controlled by the Gulf Stream, the effect of which is so broad, that you don't get the sharp temp. gradients that we get here in the States. The fronts that we get here in Texas are sometimes very powerful and can spawn tornados, hail, snow, ve... |
[
"Why is the human lifespan almost twice as long as average fertility rate?"
] | [
false
] | What is the evolutionary reason that we live for so much longer than the amount of time we are able to reproduce? | [
"I read that that's because the infant mortality rate was like 30% and, if you lived to be older than five, life expectancy was about 60."
] | [
"I read that that's because the infant mortality rate was like 30% and, if you lived to be older than five, life expectancy was about 60."
] | [
"to take care of offspring while able bodied parents were busy?"
] |
[
"Can it be so cold that clouds would freeze in the air and fall down as one massive unit?"
] | [
false
] | Or would it be too cold at that point to form clouds? But at that critical point of freezing temperature, what would happen to the clouds that are still in the air? Titanic clouds falling down like WHOMP.. shiiit.. | [
"In theory nothing is impossible, but even if this did happen it would just be an extremely rapid snowfall, and not a huge single block of ice. The amount of water in a cloud can be quite large (many tons) but it is quite diffuse. In an 'ordinary' cloud in a mass of air above freezing temperatures, the water part... | [
"No problem! There's actually a very good book called ",
" that explains the science and nature of clouds and other atmospheric phenomena really well. It's really interesting and a great read, highly recommended. "
] | [
"Well that settles that.\nThanks for taking your time to answer!"
] |
[
"I know that long term use of steroids suppress the immune system but how? I would really appreciate if someone told me how it does that to our body?"
] | [
false
] | I know that long term use of steroids suppress the immune system but how? I would really appreciate if someone told me how it does that to our body? | [
"Steroids are really a subgroup of signalling molecules called hormones. Hormones can deliver chemical messages around the body, influencing a myriad of different functions, often through their effects on gene expression.",
"Strictly speaking, we should be calling these compounds corticosteroids, a subgroup of gl... | [
"Yes. At high doses of glucocorticoids during which you may see significant lymphopenia (T-cells mostly, but B-cells to some degree as well), it is estimated that lymphopenia appears within 2 hours, peaks at 6 hours, and resolves within 24-48 hours. Note that these kinetics are with respect to a pulse dose - I'm no... | [
"so is the effect on immune system reversible"
] |
[
"Why is lithium-7 hydroxide monohydrate used as a power systems coolant? Is it considered a salt? Why it is used as a PH regulator on nuclear reactors?"
] | [
false
] | null | [
"I've been a nuclear reactor operator for 6 years. I don't know too many specifics as we didn't use this on the plant that I worked on. We used to use trisodium phosphate dodecahydrate and disodium phosphate in order maintain ph in the 10 to 11 range. You want to maintain a basic pH in order to minimize general and... | [
"LIOH is used in solution, generally in water which is used as a coolant and moderator in pressurised water reactors PWRs.",
"LiOH can be used in nuclear reactors to increase the pH in the coolant. This change in pH ends up decreasing the corrosion rate in your system which leads to lower output of deposits being... | [
"Generally it's used to help offset boric acid addition in pressurizer water reactors. Boiling reactors which use no boron don't inject lithium. "
] |
[
"If everybody had an electric car tomorrow, could the NA power grid support it?"
] | [
false
] | [deleted] | [
"According to ",
"this study",
", in the U.S., as of 2006, 84 percent of the additional electricity demand created by 220 million electric vehicles charging overnight could be met by idle generation capacity.",
"That estimate doesn't include any additional capacity of hydro, renewables, or nuclear plants, or ... | [
"Yes, because the majority of rechargers would be during off-peak hours."
] | [
"Citation?"
] |
[
"Is time dilation observed with particle accelerators?"
] | [
false
] | I'm familiar with the twin paradox - though I'm still rough on where and why the frames of reference shift for the twins - but what happens when we accelerate particles to near light speed? Do they "age"? Is this an absurd question? -edit- Actually, I think I just don't understand time dilation in general. I understand it has to to with relativity, but I don't understand what "relative" is actually anchored in, like with the twin paradox. | [
"This is a great question. The time dilation of the muons created by cosmic rays hitting the atmosphere is an example of this. As measured at rest the decay rate of the muon is fast enough that a muon created in the atmosphere should decay before it reaches the earth's surface. But we see just as many muons at the ... | [
"Yes."
] | [
"Yes.",
"This is a problem every physics undergrad solves in their special relativity course ",
" :",
"Muons have a lifetime of XXX seconds in an inertial reference frame. How long would it take a Muon to decay when it is moving at YYY speed ? (lifetime = time taken for it to decay into something stable, beca... |
[
"Apparently piranha can detect blood from 2 miles away, how?"
] | [
false
] | What is the mechanism they use to do this? And would it not take a lot of time for the pheromones to reach them? | [
"They can't. Neither can sharks. They can, however, detect very low concentrations. The blood still has to diffuse through the water and physically reach them, though. It's not like someone cuts themselves and instantly a fish 2 miles away can smell it. That's not how it works."
] | [
"I think the word is usually used more narrowly than that",
"Unless it is shark blood, it is. A pheromone affects the same species, an allelochemical affects other species. Both are examples of semiochemicals (or so says my masters thesis, at least. There seems to be differing opinions on the exact definitions)."... | [
"A lot of plants inhibit germination or growth of all plants near them. My thesis was an investigation of specific compounds from clover that could be responsible for this effect, both against other plants, which could be helpful in weed control, and against clover itself (clover soil sickness), which is a problem ... |
[
"How much does the liquid magma of the Earth affect it's surface temperature?"
] | [
false
] | So, say, if we were on just a solid rock of a planet, instead of one with a heated core, would it be a very different place to live? | [
"Very little. It depends of course on local geology, but is generally well below 1W/m2 compared to sunlight being 1000W/m2",
"You can of course see the effect on poles, there is magma under Antarctica just the same, but it's still covered with couple km thick ice.",
"So in terms of temperature it makes no diffe... | [
"This is not correct though. Good counterpoints are Venus, which has no intrinsic magnetic field, only a relatively weak induced one, and yet still has a thick atmosphere or Mercury, which has an intrinsic magnetic field and effectively no atmosphere. This comes up ",
" on AskScience and there are numerous thread... | [
"Deflects solar winds which would otherwise strip the atmosphere.",
"Wikipedia has a good overview of how it works ",
"https://en.wikipedia.org/wiki/Magnetosphere"
] |
[
"Is it possible for a falling object's terminal velocity in a given atmosphere to exceed the speed of sound within that atmosphere?"
] | [
false
] | It's my understanding that, as the fluid the object is falling through increases in density, the terminal velocity of the object will decrease while the speed of sound through that fluid increases, and vice versa as the fluid decreases in density. Is there a set of conditions under which the object's terminal velocity exceeds the speed of sound under those same conditions? Is it feasible that conditions like these could be met here, on earth? What kinds of extreme terminal velocities could be reached on earth, feasibly? I'm interested in better understanding the factors at play in determining terminal velocity, and in the extremes able to be achieved. | [
"Sure. ",
"This guy",
" broke the speed of sound in freefall about a week ago. All you need is a large, non-lifting, not too draggy body.",
"FYI, speed of sound for air at the conditions found anywhere in the atmosphere is a mostly a function of just composition (as in how much water vapor, etc.) and temperat... | [
"It absolutely boggles my mind that he couldn't hear or feel the sonic boom. I know ",
", but it's just so unintuitive."
] | [
"In the atmosphere (and any gas in general), it would seem that the speed of sound is strongly dependent upon temperature as opposed to any other variable (pressure, density, water vapor). In the atmosphere, a speed of sound profile would roughly correlate with a temperature profile in terms of its shape. Wikipedia... |
[
"Why are SpaceX trying to land their booster on a barge rather than land?"
] | [
false
] | null | [
"Rockets sending a payload up to orbit are launched over oceans. If anything were to go wrong with the launch, it is much better for the rocket to land in the ocean. Depending on how early any issues happen, the rocket could have a lot of fuel on board. If that exploded over land or worse exploded on impact and the... | [
"Several points:"
] | [
"I believe their initial tests were over land. They sent the rocket up, hovered for a few moments and landed it back on land.",
"Being over the ocean is mostly due to the massive amount of fuel on board for orbital insertion. There are likely regulations requiring this, of course, but also common sense. So, to co... |
[
"Why does the human body check the CO2 amount instead of O2 to determine if you got enough oxygen?"
] | [
false
] | null | [
"CO2 forms a buffer system in your blood , it actually exists as several different components depending on how much of it there is (CO2 +H20 => H2CO3 <-> HCO3",
" <-> CO3",
"). If CO2 builds up in your blood it causes a pH shift. The nifty thing about this is that it's (normally) easy to regulate by controll... | [
"The pH of your blood would drop, causing a condition known as ",
"acidosis",
". If it's from lack of breathing, it is specifically ",
"respiratory acidosis",
"."
] | [
"no, your saturation stays the same unless you are at altitude or a hypoxic environment in the absence of disease. SaO2 is what you're referring to"
] |
[
"How does space debris impact earth's environment and atmosphere?"
] | [
false
] | I know that it affects our space travel and satellites but does it have any affect on our environment on earth? | [
"Most space debris is dissolved by the atmosphere far before it reaches the earths surface. This is because of the massive amount of friction that the object must endure on its journey from space to our surface. Because of this, space debris does not affect the earth’s environment and atmosphere much at all. If a l... | [
"It could. This is why in most cases fuel is dumped before re-entry, especially in case of hypergolic hydrazine-related fuels, which are toxic."
] | [
"Just wanted to mention that it's less about the friction that the object experiences and more about the heat generated by extreme air compression in front of the object as it slams into the atmosphere. Kind of the same sort of concept that a \"fire piston\" camping tool uses to provide embers to start campfires."... |
[
"How do scientists know that we evolved from single-celled organisms?"
] | [
false
] | null | [
"Imagine a book by Shakespeare. Now imagine a book as complex but a lot longer.. Our genome might be that big. ",
"A bacteria's genome is considerably smaller (several fold) but from everything we know we find that their genome is basically made up of a large number of chapters that resemble very closely (70-80% ... | [
"Single celled animals came before multicellular animals."
] | [
"Really if you think about it it took billions of years, because before that 500 million years we had billions of years of just single-celled life evolving on its own. ",
"The fossil record aside, the fact is that all multicellular life is made up of unicellular organisms and that the cells are mostly made up of ... |
[
"What is super-symmetry?"
] | [
false
] | I recently watched the documentary Particle Fever and this word was used often. Can someone explain to me what it is and why Super-symmetry would be supported by the Higgs Boson having a mass of 115 Gev. And since it has been found that that the Higgs Boson has a mass of 125 Gev what could that mean? | [
"Basically it's the idea that for each particle with a given spin (electrons have a half, photons have one, etc), there is another particle with a spin that differs by one half. Some processes might occur differently if, for example, these particles were being created, but there hasn't been any evidence of that thu... | [
"I answered a similar question ",
"here",
" a while back."
] | [
"Well supersymmetry is an extension of particle physics beyond the standard model, so the idea that the standard model is the end-all-be-all of particle physics (nobody really thinks that, but it's a strong null hypothesis) is at odds with it. Supersymmetry also doesn't take gravitation into account, and we live in... |
[
"How was 20 seconds determined to be the appropriate time to wash your hands?"
] | [
false
] | If you wash your hands for only 10 seconds, does that kill only. half the germs? If you wash for 30 seconds, are you able to kill off even more viruses? What research was done to establish the current time frame of hand washing? | [
"It takes a detailed 4 or 5 minute scrub, to get practically all the germs and viruses. I don't know of any studies about 20 seconds specifically. ",
"https://www.ncbi.nlm.nih.gov/pubmed/16553905",
" Seems that \"normal\" hand washing gets rid of about 92% of bacteria; I have little idea how effective it is for... | [
"our outermost surface of our skin isnt alive, its a layer of dead cells and keratin so it doest really effect our living tissues"
] | [
"If they disrupt DNA bonds for viruses/bacteria does that mean they disrupt DNA bonds for humans as well?"
] |
[
"Will it ever be physically possible to have low latency (100ms and lower) for people in South Africa connecting to Europe?"
] | [
false
] | As somebody that lives in SA, we often have to connect to overseas servers and play with 180+/- ping, which is impossible if you want to play competitively. So with all of the talk of 5G, and other new technological advances, will low latency ever be possible, because those signals still have to physically travel to Europe and back? | [
"The main limitations for network latency are:",
"For the first, physics gives us an upper bound: the speed of light",
" which is 299 792 458 meters per second. That's the fastest anything can go, so it gives us a hard limit. At this speed, a round trip time of a bean of light between Johannesburg and Frankf... | [
"Given neutrinos' low interaction with other particles, wouldn't you have to generate a ",
" of them to send a signal that can be detected at that distance? Doesn't that place an unacceptably high lower bound on the size and energy requirements of such a transmitter?"
] | [
"See \"not practical\". It might be good enough for high speed trading, sending individual bits faster than everyone else, if the monetary incentive is large enough."
] |
[
"Why is there a correlation between positivity and geographical height in the English language?"
] | [
false
] | For example saying things such as " " vs " ", or " " vs " ". It seems so arbitrary. Did one of the first civilizations just decide this is how it's going to be? Or is there an actual scientific explanation? | [
"Why wold 'high' being better be a recent development? 'High' has meant 'great' and 'illustrious' since Old English ",
". For instance a 'highway' isn't called that because it is/was a road that's higher up, but rather it's the more important, main road. ",
"That's true of other Germanic languages too, like the... | [
"Actually, there is a proposed reason for it based in cognitive linguistics. As you pointed out, we tend to associate up with positivity and good and down with negativity and evil. The reason for this likely lies in posture. When we're healthy, we stand up straight. When we're sick, we're forced to lie down. F... | [
"There's a reasonably large amount of work exploring metaphors like this by George Lakoff and Mark Johnson, and while your point that ",
" that instantiate the general metaphor are fairly young has some merit, I think your overall point that \"TALL IS GOOD\" is a recent thing is pretty off-the-mark. First off, th... |
[
"If someone was about to be shot in the chest/torso, would it be beneficial to tense the body, relax the body, or no difference?"
] | [
false
] | Would tensing somehow minutely limit the impact at all? | [
"Theoretically, yes. Practically, probably not but maybe.",
"When muscles contract, the sarcomeres pull over each other like a million little games of tug-of-war. The final result is that the muscle becomes shorter, but denser. ",
"See animation here",
".",
"At some point (far enough distance from shooter t... | [
"If we look here",
" it seems that density of fibers increases by 25% when contracted in rats. ",
"Here",
" we have a density measurement of 1.06kg/liter in a mouse.",
"Kevlar has a relative density of 1.44, so if we work from it's capabilities and extrapolate the muscle out to now 1.325 we can see there's ... | [
"Thanks! And sorry for posting multiple times, Alien Blue was acting up."
] |
[
"If I fell asleep in an airtight room filled with only enough oxygen to keep me alive for a few hours, would I wake up before dying?"
] | [
false
] | null | [
"You would probably wake up gasping for air before dying slowly. The partial pressure of oxygen in air is 21kPa. And in blood about 13 kPa. It gets diluted as it makes it's way through the lungs. ",
"If some one was in a room with fixed amount of oxygen the concentration of oxygen in that room would fall in an ex... | [
"You would wake up after your blood oxygen levels dropped below a certain point, which is what happens to people with sleep apnoea. The level required for you to lose consciousness is lower than the level which would wake you up with a start, so you would wake up, and then probably pass out quite a bit later. "
] | [
"Then why do people dying of nitrogen asphyxiation die peacefully? They're breathing a gas with absolutely no oxygen yet they pass out and die without struggling. Same goes for people breathing helium. CO which eliminates the bloods ability to carry oxygen kills people in their sleep all the time. People only seem ... |
[
"If Robert Hooke discovered individual cells in \"micrographia\" in 1665, why is the first working microscope atributed to leeuwenhoek?"
] | [
false
] | [deleted] | [
"Honestly, I don't think it's true that van Leeuwenhoek is credited strictly with the invention of the first microscope; certainly he's credited as the father of microbiology and ",
". There were microscopes built decades before van Leeuwenhoek entered the discipline (including by such luminaries as Galileo). Van... | [
"So who actually invented the first microscope?",
"According to Smithsonian Magazine, a Dutch father-son team named Hans and Zacharias Janssen in the late 1500s.",
" They invented a compound microscope with magnification between 3x and 9x. Of course, single-lens magnifying glasses predated this compound micros... | [
"So who actually invented the first microscope?\nAlso, werent most of leeuwenhoek`s findings more or less ignored in the sense that no one else made effort in furthering microscopy till around the 1700 hundreds?"
] |
[
"So exactly what IS energy?"
] | [
false
] | null | [
"Well to ",
"put",
" it as Richard Feynman did:",
"\"There is a fact, or if you wish, a law governing all natural phenomena that are known to date. There is no known exception to this law – it is exact so far as we know. The law is called the conservation of energy.\nIt states that there is a certain quantity... | [
"In general relativity, energy conservation can be violated. Since spacetime is time-translational-variant Noether's theoerem doesn't really apply.",
"You don't need GR to violate conservation of energy. Noether's theorem ",
" applies. It applies in classical mechanics, relativistic mechanics, quantum mechanics... | [
"What is it as a \"thing\"?",
"I believe the takeaway here -- what Feynman and ",
"/u/imthedogtor",
" are driving at -- is that there ",
" a \"thing\" that corresponds to what energy is. Energy is not tangible, not ",
" -- it is a purely mathematical property that can be used to ",
" an object or syste... |
[
"Is plate tectonics really necessary for preventing continents from sinking into the sea (through erosion)?"
] | [
false
] | Numerous books (like Brownlee's "Rare Earths" say that). But on the other hand, a fairly recent discovery showed this: ScienceDaily (June 25, 2007) — A University of Utah study shows how various regions of North America are kept afloat by heat within Earth's rocky crust, and how much of the continent would sink beneath sea level if not for heat that makes rock buoyant. "If you subtracted the heat that keeps North American elevations high, most of the continent would be below sea level, except the high Rocky Mountains, the Sierra Nevada and the Pacific Northwest west of the Cascade Range," says study co-author Derrick Hasterok, a University of Utah doctoral student in geology and geophysics. "We have shown for the first time that temperature differences within the Earth's crust and upper mantle explain about half of the elevation of any given place in North America," with most of the rest due to differences in what the rocks are made of, says the other co-author, David Chapman, a professor of geology and geophysics, and dean of the University of Utah Graduate School. Were plate tectonics required to uplift the Eastern half of the U.S? Even though it probably hasn't been uplifted by plate tectonic processes for millions of years? | [
"Huh, it's nice to see news from my Alma mater, and I've worked with both of these people. But, to answer your question, if there were no plate tectonics to begin with, this would mean that the fundamental view of our Earth would have to change. There probably wouldn't be any convection currents in the mantle, whic... | [
"depends on if there is active sedimentation or erosion, but on a whole, yes it will erode until it gets to point that it becomes low enough to have standing water, and then it will most likely experience sedimentation and filling.",
"Take a look at ",
"this map",
" of the elevation of the mid-U.S. Note how i... | [
"The local temperature gradients can be determined by a number of factors, namely: ",
"When you have continental extension, and especially the wide-rift style type of extension in the Basin and Range, the temperature gradients are basically determined by the depth to moho, and the amount of stretching (which is a... |
[
"What portion of a person's calories are absorbed in the stomach as opposed to the intestines?"
] | [
false
] | null | [
"It depends on the food, only glucose can be absorbed directly into the stomach, because it does not require any digestion. Disaccharides and polysaccharides need digestion prior to absorption. "
] | [
"Also, alcohol is the only other thing to be absorbed in the stomachs itself"
] | [
"I always thought it was possible to absorb a small amount of carbohydrates in the form of glucose in the oral mucosa and stomach. (Medical personnel sometimes give orange juice or glucose paste to treat insulin shock in people with low blood sugar. It works so quickly that I always thought it didn't have time to g... |
[
"Can you refract light in a circle with the right materials?"
] | [
false
] | null | [
"Actually, you can: you make a ",
" big one, fire off the beam of light, then take the light source out and replace it with a mirror/refraction setup before the light finishes making the circuit. "
] | [
"No.",
"One way to see this is because the equations that describe the motion light can be reversed in time. If you have a setup that somehow causes light to travel in an un-ending cycle, you should be able to reverse time and watch the light going in an un-ending backwards cycle. And that right there is the co... | [
"You can make loops and insert light in them. But it's cheating and not what OP had in mind. For example lasers are sometimes built in a loop. The insertion of the light is called \"pumping\" which is in big systems nothing more than shining light on a lasing crystal.\n",
"https://www.rp-photonics.com/ring_lasers... |
[
"What species is this bird? seen in Florida"
] | [
false
] | null | [
"Hi! We generally don't do ID questions. You'll do much better in ",
"/r/whatsthisbird",
", which is full of people who want to identify birds. I'm a birder and I'm not sure what this is...was this really a wild bird from Florida? It looks like a tanager of some kind, but not anything native to the state!"
] | [
"oops! sorry was looking for a sub like that and couldn't find it! thanks for the re direction :) it was around the disney animal kingdom park, so i suppose very likely it could have been from around there"
] | [
"Good luck! I'm curious now, too. "
] |
[
"When your car windows fogs up on the inside during cold weather, is it better to use hot hair or cold air to clear it up?"
] | [
false
] | null | [
"This is what happens:",
" you'll eliminate condensation by having both sides of the window at the same temperature. Corollary: keep the aircon on, otherwise the window will fog up again because of the temperature difference.",
" you'll add capacity to the air to absorb moisture (warm air has a larger capacity,... | [
"I was told to use warm air + turn on AC so the warm air would be drier, does that make sense? But it works!"
] | [
"BOTH: Turn on the AC and turn up the heat. Assuming the ambient humidity is at all high (which is probably is if your windows are fogging up) AC coils will collect condensation, drawing some moisture out of the air before it enters the cabin. If you then heat that air up, you further reduce it's relative humidi... |
[
"When my fork or spoon scratches against a bowl or plate, does it scratch off tiny, perhaps microscopic, pieces of the bowl? If so, are these bad to digest?"
] | [
false
] | null | [
"In all likelihood, yes. However, unless you actually make visible chips, we're talking really, really microscopic here, and really small amounts. They would certainly not be big enough to cause any physical damage (cut up your intestine, for example) and most would probably pass straight through undigested. Some m... | [
"Just adding here: Ceramics are made by mixing compounds and baking them at really really high temperatures. This causes the atoms to relax to really stable configurations - if they could react with anything, they most likely already did that. So ceramics are quite chemically inert which means you can often use the... | [
"Thanks for the reply!"
] |
[
"What causes 'suicidal thoughts'?"
] | [
false
] | I'm a little bit curious after reading about the side effects of drugs such as Accutane, where a Redditor described being tempted to drive into a tree because of taking Accutane? What happens physiologically in our body that causes those thoughts? At a stretch, I understand depression, because it's...simply a disinterest in life. But actively wanting to perform an act to kill yourself...? I don't get how a drug an incite you to have those thoughts. As in, is there a 'suicide' trigger in your brain? A thousand apologies for the non-medical, unclear language I'm using. | [
"\"Suicidal thoughts\" could be defined in 2 ways: ",
"I think number 2 is more relevant to your question. This is ",
"an article",
" about ",
"this study",
" on the phenomenon, experienced by a third of the sample at some point in their lives. The researchers reach a conclusion (people misinterpret th... | [
"Originally l'appel du vide in French. It has a lot to do with existentialism and the understanding of our \"radical freedom\" in an absurd existence."
] | [
"Originally l'appel du vide in French. It has a lot to do with existentialism and the understanding of our \"radical freedom\" in an absurd existence."
] |
[
"Can a decimal be even or odd? Is there a classification for decimals like even and odd for whole numbers?"
] | [
false
] | If I have the number 2.2, which looks even at first glance, and divide it by 2, I get 1.1. To determine if a number is even, it must be divisible by 2 and produce a whole number. Obviously this isn't the case, so therefore 2.2 isn't even. But does that necessarily mean it's odd? Is there a different type of classification for decimals like we have for whole numbers? | [
"\"Even\" and \"Odd\" apply only to integers."
] | [
"You can talk about evenness of rational numbers. Take a fraction A/B, where A and B are integers, and factor out all the 2's from them. If there is a positive power for the 2's then the rational number is even, if there are no 2's, then it is odd. If there is a negative power for the 2, then they are like, super-o... | [
"It can help us identify p-adic integers. If |x|",
"<=1, which happens exactly when x is not \"super-odd\", then x is a 2-adic integer. This is pretty handy in number theory and p-adic analysis in general. Though, we don't call things \"super odd\". "
] |
[
"Theoretically, could we selectively breed out or drastically reduce the need for sleep?"
] | [
false
] | Let's say we have animal 'X' which reaches reproductive maturity in say, 1 week. Is there some sort of chemical indicator that we can identify that correlates with a decreased need for sleep which can subsequently be enhance with focused breeding? Edit: I guess I should note that animal 'X' has no qualities that are outside of normal bounds. It can be any animal you choose provided it exists (cat, rat, sloth etc) | [
"Coincidentally I recently came across ",
"this article in the Wall Street Journal reporting on the 1-3% of the population that need less than 6 hours of sleep",
"Dr. Fu was part of a research team that discovered a gene variation, hDEC2, in a pair of short sleepers in 2009. They were studying extreme early bir... | [
"They might be mistaking the cause and the symptom. It could be possible that the gene causes them to be more healthy/upbeat/resilient and that in turn causes them to need less sleep."
] | [
"Either way, I'm jealous. "
] |
[
"What's so special about beef that humans can basically eat it raw and not get sick?"
] | [
false
] | null | [
"Most harmful bacteria that will contaminate beef requires oxygen so it's only alive on the outside of your steak. Searing the outside and leaving the inside raw kills the baddies on the outside while the inside was already fine.",
"Also that's why you're supposed to cook hamburger more because once ground up the... | [
"Your oxygen point isn't quite right. It has to do with the poreousness of the beef itself. Beef is not very poreous and as such the bacteria isn't able to get down past the surface like it is with chicken, which on the flip side is very poreous as compared to beef."
] | [
"what adaptations do predatory animals have to avoid becoming ill from consistently eating raw meats?",
"Animals that eat raw or rotten foods have a stomach that provides a much harsher environment to ingested microbes. The extreme example are the carrion eaters such as vultures that can eat dead and rotting fles... |
[
"Why can’t fish get rabies?"
] | [
false
] | Hi all, Aquarium enthusiast and 2x rabies shots recipient. I have lived dangerously so to speak, and lived! But I have a question for you all. I was at my local fish store joking with the owner who got gouged by one of his big fish (I think a cichlid). I made a joke about rabies and he panicked for a brief moment, until I told him it’s common knowledge that fish don’t get rabies. I was walking home (and feeling bad about stressing him out!) when I started to wonder why. For instance, the CDC says only mammals get rabies. But there’s a case of fowl in India getting rabies. I saw a previous post on here that has to do with a particular receptor that means birds are pretty much asymptomatic and clear it if exposed. Birds have been able to get it injected in lab experiments over a hundred years ago. I also know rabies has adapted to be able to grow in cold-blooded vertebrates. So, what about fish? Why don’t fish get it? Have there been attempts to inject fish in a lab and give them rabies? Or could they theoretically get it, but the water where they bite you essentially dissipates the virus? Or is there a mechanism (e.g. feline HIV —> humans) by which the disease can’t jump to fish? Thanks for any insight. I will be watching Roger Corman’s “Piranha” while I wait on your answers. | [
"Rabies basically enters via the muscles and is transported into the motor neurons preferentially (though I believe sensory neurons are also affected- someone else can jump in here).",
"The cells themselves at the point of infection, and cell membranes probably aren’t any less susceptible (this is an in vitro stu... | [
"Good metaphor, thanks!"
] | [
" binds to the p75 neurotrophin receptor which is highly conserved in mammals. Other vertebrates also have it but it's structured differently; rabies has adapted to infect reptiles, and we've artificially infected birds and even insect cell cultures. There's no reason it ",
" infect fish though temperature might ... |
[
"Do the \"Smart Alarm Clock\" smartphone apps really wake you up at the ideal time by monitoring your sleep cycles?"
] | [
false
] | I know there is legitimate science that explains sleep cycles & rhythms but is the simple app plus gyro-meter in a handheld smartphone really adequate to wake you up at the ideal time? I've heard many anecdotal success stories but my suspicion is they may be placebo induced. | [
"It CAN work for some people, but is by no means perfect. It is certainly based on some scientific principles (i.e., movement can be a marker of transitional sleep stages). The problem is that movement is not a reliable marker of transitional sleep stages in everyone, and there can even be significant individual ... | [
"polysomnographer here. I doubt it but maybe. Understanding what sleep level people are in takes eeg monitoring (brain waves which are different in every stage) eog monitoring (eye movement which will show rapid eye movement in REM) and emg (muscle activity, and in REM the body paralyzes from the next down as to no... | [
"I researched these in college.",
"The apps are a huge problem if you sleep with a partner, a pet, or get up throughout the night to urinate or acquire water. These can all produce false positives that will throw off the phone's interpretation of your \"rhythm\". ",
"It certainly works for some people (the popu... |
[
"Do we have any idea what prevents the massive force of repulsion between the protons in the nucleus of the atom?"
] | [
false
] | Are there any interesting theories out there? Or are we completely clueless? Also, I would love to see some interesting articles linked here! | [
"The \"strong nuclear force\" is a completely different thing, much stronger than the electric force at short ranges, and it doesn't care about electric charge."
] | [
"Nothing prevents it; they ",
" feel electrostatic repulsion due to each others' charge.",
"However there's a much stronger, usually attractive force between nucleons. It's the residual strong force. This is why nucleons bind together and form nuclei."
] | [
"Ah ok that makes more sense. Still find it odd that there is a large attractive force between subatomic particles of the same charge..."
] |
[
"How dense were dinosaur populations (e.g., t-Rex, velociraptor, brontosaurus) at the height of their respective time periods?"
] | [
false
] | [deleted] | [
"I would think sauropods, being massive herd animals, required quite a bit of room to graze. Realistically how many animals could one herd of creatures that size consist of?"
] | [
"I would think sauropods, being massive herd animals, required quite a bit of room to graze. Realistically how many animals could one herd of creatures that size consist of?"
] | [
"Its not so much about how many is in a herd but how big of a area does that herd range. You could have hundreds of individuals in a herd but only a herd for every hundred miles or it could be two to a herd but a herd every few miles."
] |
[
"Biology: When you wake up in the morning and your covers aren't all bunched up(meaning you didn't move much in your sleep) does that really mean you got a \"deeper\" nights rest?"
] | [
false
] | I don't know much about sleep or sleep patterns, but I'm curious to know a little more about this topic. | [
"All I really know is from what I learned in my AP psychology class this year, which isn't much :/. I just remember my mom always saying that if I didn't move around much in my sleep, I mustve slept \"really good\". Just curious to see if there's any truth in what she's saying. "
] | [
"If that is all yes there is some truth to it. Your mom did not lie to you."
] | [
"Well if your covers are not disturbed, you may or may not have moved much during the night. But if the covers are all at the foot of the bed, or hanging off the ceiling fan, then you certainly HAVE done some moving around...."
] |
[
"How important are the expiration dates on food really? Obviously it's certainly an issue for perishable food, but do the expectation dates really matter for dry goods and canned food?"
] | [
false
] | null | [
"Canned food, which has been completely sterilized, is preserved for infinity - as long as the container is intact and keeps the contents sterile. No microbial processes will spoil the food, however if acidic substances are stored in tin cans (like vegetables), the acids might interact with the tin coating, thereby... | [
"Obviously it's certainly an issue for perishable food, but do the expectation dates really matter for dry goods and canned food?",
"Even here it's less an issue than most people believe. Even with highly perishable foods such as yogurt and all-natural cream cheese the expiration dates don't mean to much. It is M... | [
"I guess it comes down to having your brand name associated with product quality.",
"Selling electronics/cars/ect. that break every year makes a lot of sense if you want to boost sales, it doesn't mean it's a good economic choice for your company. (It also doesn't mean it's necessarily bad - e.g. Apple. The produ... |
[
"How would the images on the Golden Record (on Voyager 1) be displayed?"
] | [
false
] | Is there like some sort of projector that lights up or something? I have no idea how the images will appear. I guess I understand how to start it, however what happens after? | [
"Nope. There’s a stylus to read the record just like a vinyl record and some instructions on the back to interpret the analog signal and a “You got it right”-welcoming screen that will show a perfect circle if everything is calibrated correctly. ",
"So other than the record and stylus it’s BYO when it comes to sh... | [
"an alien civilization that can intercept an interstellar space craft",
"That's a really important point. The chance that Voyager hits something is tiny, and even if it would hit a planet it would burn up or get destroyed by the hard impact. It won't be studied by people who just discover how sound waves work. To... | [
"Each image is encoded in binary on the disc in three channels: Red, Green, and Blue. The first image is a white circle so if they decode any one of the channels correctly, this will be the first clue.",
"There are also instructions that show each image is constructed from 512 vertical lines, with 8ms between eac... |
[
"Can I save myself from \"nerve gas\" poisoning by ingesting tomato leaves?"
] | [
false
] | Looking at how atropine is used as first-line treatment for poisoning by organophosphate nerve agents like Sarin, Soman, Tabun, VX etc. (i.e. anything that acts by inhibiting acetylcholinesterase enzyme), would naturally occurring tropane alkaloids administered orally have the chance to save my life, or reduce the damage, if administered soon after exposure? Would oral administration by anywhere near fast enough, what kind of dosage would be appropriate, and how likely am I to accidentally give myself a fatal dose of atropine? What effect would the other alkaloids have, i.e. scopolamine, etc? Thanks guys, as always. EDIT: Spelling | [
"As a graduate from the US Army's Nuclear, Biological and Chemical school, I'd say no.",
"We were taught that even the atropine auto-injectors that the military issued would likely be useless if you got a good dose of Sarin or VX. The atropine was just issued as a \"hope for the best/better than nothing\" type of... | [
"Right. I was guessing that perhaps there was some amount of hope because when I was reading about the Tokyo Subway Sarin Attack, when the victims were being treated in hospitals hours later, some doctor who recognised the symptoms of nerve agent poisoning faxed information about the antidote to the city's hospital... | [
"If tomato leaves contained any kinds of alkaloids which were useful I suspect they would be in far far too lower concentration. Most natural products are. You'd have to eat tonnes of leaves. Also the time for the leaves to be digested and make their way into the bloodstream would be orders of magnitude slower than... |
[
"Is unplugging an electronic device that is fully charged, then plugging it back in so it charges more bad for the device?"
] | [
false
] | I've noticed that every rechargeable battery, if unplugged then plugged back in, keeps charging. Is this increasing the charge? Does it hurt the battery or cause it to wear out faster? | [
"When your battery reaches ~95% charge most devices will 'trickle charge' i.e. they will add small amounts of charge compared to the normal charging. They do this because it isn't good for the battery to be fully charge for long periods of time, they can lose their capacity over time if you do this a lot.",
"By u... | [
"It depends on the type of battery used in the device and the battery-specific term is called \"short cycling\" if you wish to look into it more.",
"The short answer is there's no harm, at least with respect to the ubiqutious Lithium-ion batteries or Nickel Metal-hydride. Its an idea left over from rechargeable N... | [
"Thanks for the response and the source!"
] |
[
"If humans survived for 100 thousand years, wouldn't the evolution of some species be obvious to see?"
] | [
false
] | null | [
"Biology"
] | [
"Biology"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"A good home for this question is our sister subreddit ",
"/r/AskScienceDiscussion",
" because of its open-ended or speculative nature. Please feel free to repost there!",
"Please see our ",
"gui... |
[
"What, physically, happens when I get the wind knocked out of me?"
] | [
false
] | When I was younger I thought it was my lungs fully emptied, but that doesn't make sense. Is the diaphragm going too far one way? Is it a by-product of evolution? | [
"Unfortunately this is a common misconception. The celiac plexus is located deep to the diaphragm and actually has no contribution to diaphragm activity (it functions to help regulate your foregut). It is correct that having the wind knocked out of you is due to a diaphragmatic spasm, but this is directly due to th... | [
"Getting the wind knocked out of you is often a response to a hard blow near your solar/celiac plexus. ",
" The force of the impact causes your diaphragm to spasm, causing it to not work as intended.",
"Until the spasm goes away, your diaphragm will have trouble working properly.",
"Source: ",
"http://en.wi... | [
"Whoops, you're totally right. My bad, thanks for the correction."
] |
[
"Do vinyls really have a better audio quality than CDs?"
] | [
false
] | I think everyone knows a person, which loves vinyls and often states how much better the sound is. The theoretical background behind this assertion is, that a digital saved audio file can only have a finite accurateness, while this is not true for analag stored audio (until the effects of quantum physics occur etc.). But my question is: Do vinyls have a better sound than CDs? CDs have a samling rate of 44.1 kHz, so as per the sampling theorem one can represent frequencies up to 22 kHz, which is enough for humans (afaik). The samples have 16 bit, I do not know whether humans could hear a difference if they had 24 or 32 bit. On vinyls, a major drawback is in my opinion the loss that occurs when pressing the vinyl and when reading the information (I think noise when reading the information is unavoidable). I also heard, that the rotational velocity of vinyls is too low and that with a higher speed one could achieve a more exact representation of the original audio. I have searched the web, but I only found biased discussions between "digital" and "analog" lovers, are there any studies on that topic etc?. Edit: Thanks for the answers. I did not think that there are so many factors which play a role in representing the audio signal. | [
"I have searched the web, but I only found biased discussions between \"digital\" and \"analog\" lovers, are there any studies on that topic etc?.",
"When it comes to high-end audio and music listening gear, the placebo effect plays a huge role in people's perceptions. More importantly, when people make qualitati... | [
"This is a fantastic video that explains the digital side of things from the guys who make the Ogg Vorbis encoder and a lot of other good stuff.",
"http://xiph.org/video/vid2.shtml",
"In general, 44.1 KHz is enough for anyone and is capable of perfect fidelity (more can sometimes introduce noise if the speakers... | [
"I will not attempt to answer the entire question, but I will add this to the discussion. A vinyl record decreases quite drastically in quality as the needle moves from the outside edge, to the center. This is because rotational speed is constant, while the radius of the circular groove gradually decreases while th... |
[
"How do we detect what colours an organism can perceive?"
] | [
false
] | I understand colour blindness tests in humans, but they can verbally communicate. How do we know that dogs are colour blind or that the mantis shrimp can perceive more colours than we can? | [
"the main way to understand animal color vision is to see what photopigments are expressed in their retinas (or whatever they have). in vertebrate vision, each photopigment serves as one dimension in the visible color space, so the more pigments you express, the larger the space of colors you can experience. humans... | [
"You are very kind. Thank you very much for you detailed explanation! "
] | [
"Good explanation. One thing I'd like to add: just because an animal has more photopigments, or photopigments that cover a larger range on the spectrum, doesn't automatically mean that it perceives more colors. Color discrimination ability is an important factor that can be revealed by those behavioral tests. Show ... |
[
"Does all baryonic matter decay?"
] | [
false
] | Does the Universe have a unique “ground state” where entropy dictates matter inevitably go? | [
"The lightest baryon is the proton. So if baryon number is really always conserved, the best we can do is have all baryons decay into protons.",
"Well we \"know\" that baryon number is not conserved at high energies due to the Adler-Bell-Jackiw anomaly of the standard model such that only B-L is conserved.",
"A... | [
"The lightest baryon is the proton. So if baryon number is really always conserved, the best we can do is have all baryons decay into protons.",
"Well we \"know\" that baryon number is not conserved at high energies due to the Adler-Bell-Jackiw anomaly of the standard model such that only B-L is conserved.",
"A... | [
"Do ",
" elements decay? To what?"
] |
[
"AskScience Cosmos Q&A thread. Episode 8: Sisters of the Sun"
] | [
false
] | Welcome to AskScience! If you are outside of the US or Canada, you may only now be seeing the seventh episode aired on television. If so, This week is the eighth episode, "Sisters of the Sun". The show is airing in the US and Canada on Fox at Sunday 9pm ET, and Monday at 10pm ET on National Geographic. Anyone can ask a question, but Popular science shows, books, and news articles are a great way to causally learn about your universe, but they often contain a lot of simplifications and approximations, so don't assume that because you've heard an answer before that it is the right one. If you are interested in general discussion please visit one of the threads elsewhere on reddit that are more appropriate for that, such as , , and . Please and . We'll be removing comments that break our rules and some questions that have been answered elsewhere in the thread so that we can answer as many questions as possible! | [
"A bit of a correction to the science in the show: Not all supernovae are actually nuclear explosions. ",
"The show portrayed the death of the star Rigel in a ",
"core collapse supernova",
", which is indeed the expected fate, but Tyson incorrectly referred to it as a nuclear explosion. In fact a core-colla... | [
"With a show as broad as Cosmos you're going to see a lot of generalities and some innacuracies to appeal to a brlad audience. Sagan had the same problem when he started talking about the Library at Alexandria for example."
] | [
"It is tightly bound by its own gravity, so it does not disperse. It will be a small dark ball of mostly carbon and oxygen. This phase could be called a ",
"black dwarf",
". There are not expected to currently be any black dwarfs in the universe, because the universe is not old enough for a white dwarf to ha... |
[
"If I moved a lake (includes plants, fish etc.) from here to mars, would the inhabitants survive?"
] | [
false
] | null | [
"Think about what sort of things fish, other marine life, and plants need to survive on earth. Then think about the environment of the earth is different than the environment on mars, and if the life in the lake could handle that kind of change. ",
"I'll start you off with one. Earth is the 3rd planet from the... | [
"There is a rare atmosphere on Mars. It exists, but pressures are so low that water would boil away. "
] | [
"Except that the ice is going to sublimate from the top down on warm days (depending on latitude), progressively exposing more water to freezing. "
] |
[
"True Zero G"
] | [
false
] | [deleted] | [
"It depends what you mean by \"zero g\". One of the fundamental tenets of general relativity is that acceleration and a gravitational force are fundamentally indistinguishable. If you're stood inside a sealed box, there is no experiment you can perform which will tell you whether you're stationary in a gravitationa... | [
"I did specify a point mass because of this, but I should have been clearer about the simplification made. Apologies."
] | [
"One of the fundamental tenets of general relativity is that acceleration and a gravitational force are fundamentally indistinguishable.",
"That's not true - if it was, then there would be no such thing as gravity, since GR is a diffeomorphism-invariant theory (i.e. it works in ",
" reference frame). You cannot... |
[
"Do we get heat from other stars?"
] | [
false
] | So we are heated by our sun but do others starts also heat us or are they just too far? If we do get heat, how much do we get? | [
"Your answer to this question is very good. There are a few interesting exceptions though. If for example Alpha Centauri were to go supernova things would change a bit, a bright supernova can be more than 10",
" brighter than Alpha Centauri. Meaning it would heat up Earth to a significant degree. Only for a shor... | [
"All forms of radiation, including heat, have the relative intensity of 1 over R squared. Put another way, if you increase the distance that you are from a star by a factor of 2, you receive a quarter of the energy. The Earth is approximately 93,000,000 miles away from the sun, a distance that can be represented by... | [
"Whenever I think of this, I can't help but be amazed at the sensitivity of the human eye. True that there are many stars JUST under our visual acuity, but a starry, clear night away from any city is pretty shocking. The eye can pick up a tiny, tiny amount of energy.",
"I've noticed that dark nights on the beac... |
[
"If a lack of sunlight has the propensity to make us depressed, why did humans migrate to the Arctic Circle?"
] | [
false
] | . | [
"Because lack of food has a tendency to make us dead"
] | [
"Depression isn't something that is going to take immediate hold or even necessarily have a detrimental effect that would effect reproduction. There's resources up there, and we can live up there and breed successfully. So we went, and the reduced competition doesn't hurt either. "
] | [
"Were central (laterally speaking) Europeans forced Northwards due to a lack of food?",
"(Sorry, my knowledge of ancient human migration is poor.)"
] |
[
"When you're running and you get a stitch, what is actually happening? And what causes it?"
] | [
false
] | [deleted] | [
"This phenomenon is known as '",
"exercise-related transient abdominal pain",
"' (ETAP), and unfortunately while a number of theories exist we don't know definitively what its cause is. The ",
"leading hypotheses",
" include 1) diaphragmatic ischemia, 2) peritoneal irritation, and 3) stress on ligaments su... | [
"It is important to be a bit careful here. ",
"It is easy to show it causes extra weight.",
"\nIt is easy to show it results in more stitches. ",
"Not so easy to show the extra weight is what is causing the stitch, and eliminating all other causes. "
] | [
"I'd imagine the difference is being ",
" versus having a stomach full of water."
] |
[
"Is it possible for human clones to evolve?"
] | [
false
] | For example, if you were to make a clone of yourself and that clone were to make a clone of itself, is it possible for it to evolve over time? | [
"It should be noted that individuals don't evolve. Populations, however, do."
] | [
"Thank you for that. So depending on the time of cloning it could evolve... I've been wondering that ever since watching that DQ commercial. "
] | [
"Short answer is yes. Cloning would mean that the clone has the same DNA as the donor at a single specific time. From birth the clone would then grow up developing random mutations as any normal person would, these would then be passed on to a future clone. ",
"Edit: You would probably see a little less evolution... |
[
"Is terraforming of Ganymede feasible?"
] | [
false
] | null | [
"NOTE: Speaking off-flair here as someone with a laymans interest in this sort of thing.",
"It depends on what you mean by \"terraform\". First off, the thick atmosphere of Titan is due to the fact that it is extremely cold. Atmosphere retention is a function of planet mass and temperature (and sources of gas, ... | [
"For further reference on why temperature is important at Ganymede, have a look at ",
"this graphic. ",
" The surface temperature would need to be drastically increased before the atmosphere was breathable. ",
"Further, ",
"the total solar irradiance at Jupiter is ~27 times less than at Earth",
", meaning... | [
"I learned awhile ago that any question requiring speculation, particularly those related to science fiction, are absolute karma graveyards for anyone actually giving scientific responses. People really, really don't want to learn that they will never travel the stars in faster-than-light space ships. I personally ... |
[
"Why is cycle detection the key to integer factorization?"
] | [
false
] | I have been spending a lot of time lately with Pollard's Rho algorithm for integer factorization. While I have managed to implement it and I've tried both Floyd's and Brent's cycle detection algorithm I don't really understand why we're looking for a cycle to find a non-trivial factor of n? What does the sequence generated by g(x) = (x + 1) mod n represent? I understand the cycle detection algorithm itself (letting a function work its way through the sequence faster than the other function (i.e. the hare and the tortoise)) but I do not understand how this translates to finding a non-trivial factor to n? | [
"A short summary:",
"Cycle detection is not the key.",
" are the key.",
"The sequence (x",
" + 1) represents nothing; it is pseudo-random.",
"Let's say we have a pseudo-random sequence (a_i) of integers mod n, where n=pq with p and q unknown. If, by chance, we find i and j such that a_i ≡ a_j (mod p) but ... | [
"What are you even talking about? Are you sure you wrote this in the intended place?"
] | [
"Yeah, well, simply stated there is nothing in the universe that is random, what you have are equations, nothing more, nothing less.",
"so all this talk about random had far more to do with things like wishful thinking than anything else."
] |
[
"Using VOIP, is there a maximum bandwidth of data that can be transmitted?"
] | [
false
] | Consider this thought experiment: I initiate a perfectly stable VOIP call to a machine which can translate verbal english into a file. I spend 1 hour reading the contents of which is 4,749 KB, resulting in me transferring 1.350 KB of "real" data per second, with the VOIP call (using G.729 and 8kb\s), in reality consuming 28.1 MB to transmit the file. Now say perhaps I verbalize the file in 9 min 53 seconds instead of 1 hour. Rather than 1.35KB\s, I've transmitted at almost exactly 8kb\s, the same rate that the VOIP connection itself requires. What happens if I were to verbalize the file in 9 minutes then? Does the 8kbps that the VOIP call maintains act as a maximum bandwidth that can be transmitted? At 9 minutes, I'd be transferring data at 8.79 kbps, which is higher than the VOIP connection itself. Would this data simply be lost? In my example above, I the maximum bandwidth that the system could handle. If I wanted to initiate a new and different connection without knowing the maximum bandwidth, is there any way I can be sure that my message gets delivered without data loss? | [
"VoIP typically uses ",
"audio compression",
" for audio data transmission. While there are a pretty wide variety of algorithms currently in use (depending on the provider), most of the compression algorithms used fall into one of the following categories:",
"In all three situations, data is lost. There rea... | [
"Per your answer, perhaps I use narrow-band compression, and attempt to transmit at a higher bitrate than the VOIP connection actually supports. ",
"That's really not possible. The best you can do is saturate the link. It isn't as if an application ",
" a certain amount of bandwidth. VoIP systems just send a... | [
"but is there any way to determine what data is affected?",
"You're up against two things, one is the theoretical maximum data transmission rate. Followed by limits to the encoding used by the VOIP system. The latter point is important because the compression used by VOIP will be optimized for voice and will prob... |
[
"Every once in a while my toothpaste tube spontaneously explodes. Why?"
] | [
false
] | It has a hinge cap and sometimes it opens itself and oozes out all over the counter. I assume it has something to do with pressure. Is the toothpaste evolving gas? | [
"Your ",
" leaked? How is that possible?"
] | [
"The tube probably somehow got hotter, so the toothpaste expanded."
] | [
"I'm looking at this on my phone, so I can't read the small print - does this toothpaste contain bicarbonate of soda, by any chance?"
] |
[
"What type of genetic mutation causes Phenylketonuria (PKU)?"
] | [
false
] | I've searched through the internet and I can't seem to find any conclusive discussion or explanation about what type of genetic mutation causes PKU - does anyone, in this field, know what it is? | [
"In addition to the above answers; there are around 5 tipes of PKU with clinical significance. Each is caused by a different mutation in a different enzyme. Most (I do not dare say all) enzymatic reactions in the body are just parts in a greater machine; Glucose to glycogeen takes many steps. Just so, many steps ar... | [
"PKU is caused by mutations to the gene Phenylalanine hydroxylase. A quick wiki search tells me that there are ~300-400 distinct mutations that have been identified as causing this disease. Most are missense mutations, and most (as expected) occur in the catalytic domain of the enzyme. "
] | [
"PKU is defective phenylalanine metabolism. The metabolism of phenylalanine to tyrosine is dependent on an enzyme called phenylalanine hydroxylase. So any mutation that causes a change in the enzyme's amino acid structure (and hence shape and function) [missense mutations and even frameshift mutations] or premature... |
[
"Do mosquitoes do anything for the ecosystem?"
] | [
false
] | [deleted] | [
"It's been estimated that in Alaska alone, mosquitos weigh ",
"96 million pounds",
" [1]. ",
"Taking 50,000 tons of nutrition out of an ecosystem seems like it's going to lead to serious consequences."
] | [
"I'm glad you clarified. I was terrified of Alaskan mosquitos for a minute."
] | [
"Yeah, I mean that would be at least ten."
] |
[
"why do most of the planets revolve around the same plane?"
] | [
false
] | null | [
"Source: I'm an astrophysicist.",
"The reason is the physical principle known as conservation of angular momentum.",
"Before the planets formed, the solar system was just a giant cloud of dust and gas. Initially, the cloud had some net spin. As it collapsed, it began spinning faster and faster (just like an ice... | [
"Yep, the same goes for galaxy evolution too, but not really for galaxy clusters. Clusters don't really flatten out at all, but they do cluster into filaments because of gravity."
] | [
"I also notice that our galaxy is also pretty flat. Does this extrapolate further out to clusters of galaxies?"
] |
[
"Could a \"flash freeze microwave\" be made to flash freeze food?"
] | [
false
] | So, I know that microwaves head up the water molecules, in turn heating up the food very quickly. But could it be possible to do the opposite, to freeze water molecules very quickly to intern freeze the food? | [
"No. Its vastly easier to add energy to a system than to remove it."
] | [
"The closest thing I can think of is ",
"Doppler cooling",
", but its capabilities are nowhere near what you're describing."
] | [
"Setting aside methods like Doppler Cooling, which can only be used to cool very small amounts, on the order of individual atoms, there isn't a way to do what you're suggesting.",
"To add heat to a system, you need to add energy. Microwaves do this by emitting light, the magnetic field of which causes some of th... |
[
"physicists say to laymen \"observing a quantum particle causes the wave function to collapse\" but what does this mean mathematically? what does a collapsed function look like compared to the original?"
] | [
false
] | null | [
"Here is an example",
", where the quantity being measured is the position of the particle. Initially it has a wavefunction which is a superposition of many locations in space. After the measurement, the particle is localized at a single point in space, and its wavefunction becomes like a Dirac delta function at ... | [
"Well the original function can be arbitrary wavefunction, and the final function is a Dirac delta function. I can make up a function for the example in the picture, it looks like a Gaussian function.",
"So the original wavefunction would be something like",
"f(x) = N*exp[-k((x-x",
")",
"+(y-y",
")",
")... | [
"The most important thing to know about that statement is that \"an observer\" doesn't mean a guy looking at it. To be \"observed\" just means anything of any type interacting with it an iron atom can \"observe\" another atom if it interacts with it in any way. People put a lot of spiritual significance on a choice... |
[
"Why is it so hard for women to get pregnant?"
] | [
false
] | Or am I just misinformed? In my personal experience it took me years before I got pregnant, and I've heard so many people say it just takes time. You know the classic scene of a woman telling her husband she's ovulating - such care goes into trying to get pregnant, why is it so hard? What is it about us that prevents trying couples from getting pregnant within the first, I dunno, month of trying? Has it always been this way? | [
"Well the fertility rate in men has been dropping significantly across the board. One study associates it to ",
"pollution",
" but there is much speculation over ",
"other factors",
".",
"\"The latest scientific studies have also shown that the average sperm count has fallen by up to 50% from 380 million... | [
"It's not necessarily that hard. 85% of couples having regular unprotected sex will conceive within a year, 95% within 2. ",
"Source"
] | [
"Also conjecture, but I wanted to point out that due to women seeking careers before having a family more often nowadays, many women are having children later in life. This has an affect on both parent's lowered fertility due to age. ",
"Whereas in the recent past it was not uncommon for a woman to become pregnan... |
[
"Can a larger black hole pull out objects within the event horizon of a smaller black hole?"
] | [
false
] | null | [
"No. ",
"In addition, if their event horizons touched, the two black holed would merge to form one larger black hole."
] | [
"It's not quite as simple as that. One feature of the equations of General Relativity is that they are non linear, which means if you know two different individual solutions, their sum is not necessarily going to be one. Classical gravity and all other forces are, however, which is why we intuitively assume it as ... | [
"Layman here, ",
"Wouldn't the gravity of a second black hole reduce the net force on an object between them, even deforming the actual event horizon of the first? Wouldn't there be some kind of Lagrangian point between them that could even lie inside the original event horizon? "
] |
[
"Why does metal spark in the microwave?"
] | [
false
] | null | [
"Microwaves are electromagnetic waves, meaning that they (like light, radio waves, and other forms of electromagnetic radiation) can potentially induce a current into a conductor. ",
"This is how radios work. You generage an oscillating (think sine wave) electrical signal in a long metal rod (transmitting antenna... | [
"conducted on the surface of the metal; it does not get absorbed by the conductor. This is why most thick cable is strands of smaller wires braided together, like a rope.",
"There is not a significant decrease in resistance for stranded wire vs solid because all the wire strands are shorted together. Further the... | [
"conducted on the surface of the metal; it does not get absorbed by the conductor. This is why most thick cable is strands of smaller wires braided together, like a rope.",
"There is not a significant decrease in resistance for stranded wire vs solid because all the wire strands are shorted together. Further the... |
[
"Does an hourglass flow at a constant rate? If so why?"
] | [
false
] | I feel as if it would slow down slightly as there was less pressure from the sand above it. Can you explain some of the fluid dynamics or relevant physics for why it behaves the way it does? | [
"Sand granules are too large and static to follow the physics of fluid dynamics, at least at the scale of an hourglass, so there isn't really a \"pressure\" to speak of. Instead, contact forces distribute weight downwards unevenly. (Uneven force distribution is present in fluids as well, but the constant particle m... | [
"This is just a guess.",
"please avoid speculation in this subreddit."
] | [
"This is just a guess.",
"please avoid speculation in this subreddit."
] |
[
"This may be the wrong sub, but do you think this could make a pina colada without a blender?"
] | [
false
] | null | [
"It completely depends on the ratios of ingredients. A large enough amount of sugar, milk fat, and vodka in there will make it slushier. Any alcohol especially lowers the freezing point and makes things slushier. You'll have to experiment. "
] | [
"...but as far as you're aware this would work?"
] | [
"There exists some ratio of those ingredients for which you will get a slushy-like substance, but I cannot guarantee it will be a worthy substitute for using a blender."
] |
[
"What is the speed of a bubble rising in water a function of? And is there an absolute limit on that speed?"
] | [
false
] | null | [
"/u/Asinus",
" is correct that the rising force is due to the principle of buoyancy, and ",
"/u/perso_nel_mondo",
" is correct that Stoke's Law can be used to calculate the terminal velocity for a rising bubble - however only for small bubbles where the viscous drag dominates and the droplet is still spherica... | [
"The go-to piece of information here is Stokes' Law which relates fluid viscosity, drag, size (bubble size, in this case) and velocity. ",
"To interpret in the context of a rising bubble, the absolute limit on speed occurs when the buoyant force equals the drag force. So, from Stokes, as velocity increases, drag ... | [
"As others pointed out, this is not an easy subject. Yet it has been extensively treated in literature, beacuse of the many industrial fields where you need to know the behaviour of gas-liquid interface.",
"Most discussed is probably the flow of bubbles in tubes, or the formation of bubbles on a surface liquid-so... |
[
"What happens if primordial black hole evaporates in the Earth's atmosphere ?"
] | [
false
] | I read that small black holes could have formed in the early universe and that there is a possibility that they move through space and actually could hit the Earth. Depending on their mass they actually could pass through the planet without doing measurable damage, since they are so small and don't influence many particles with their event horizon. But I am more interested in what happens, when a black hole evaporates through Hawking radiation. It is often stated that since the rate of this radiation would become increasingly stronger when the black hole becomes smaller, it will eventually end in "burst of energy". But how massive would such a burst be? I read somewhere a 1000 ton black hole would evaporate in just over a minute. What would happen if it was flying through our atmosphere during his last breath? Would it cause destruction? | [
"I found a calculator for the intensity of Hawking radiation on a ",
"website",
". I am not exactly sure how to interpret the numbers though. The luminosity seems pretty high but I don't know what effect it would have if it came from an event horizon that is way smaller than a proton.",
"According to this cal... | [
"We don't know exactly what goes on as the black hole shrinks to nothing, as far as I know.",
"You can just quickly look at ",
"the Hawking radiation equations",
" and see that Hawking radiation temperature as well as instantaneous power outflow are inversely proportional to black hole mass, which means the p... | [
"Safe to say, it would not look good. According to some science in an answer ",
"here",
", the explosion from a black hole with a mass of 5 grams would be three times stronger than the Nagasaki and Hiroshima atomic bombs combined, and I seriously doubt anything would get better if you increased the mass, it wou... |
[
"Are the benefits of fish oil (omega-3) pills proven?"
] | [
false
] | As the title asks, am I benefitting from this substance, or am I wasting my time and money consuming fish oil tablets. Note: I also eat fish at least once a week. | [
"The Omega-3 ester extract of fish oil has been proven stringently enough to reduce triglycerides to be ",
"approved by the FDA as a pharmaceutical."
] | [
"Related: Can people with Fish allergies take them? "
] | [
"I can't answer whether they'll aggravate your allergies but I can say this. There exist plant versions of the omega 3's. They're found in flax seeds (as well as other plants). Your body will convert the omega 3's in them into the animal forms (EPA/DHA). The conversion rate is awful though, something like 10%, but ... |
[
"How valid are the claims that fluctuations in solar activity can account for a significant portion of our global warming woes?"
] | [
false
] | I know that it is pretty well understood that humans are contributing to global warming but I was trying research the validity of some of the claims that it may not be as bad as the hype. What role does solar activity play in climate models? How much do we really understand? Is there a consensus in the scientific community about it's role? | [
"Sallie Balliunas tried desperately to connect solar fluctuations and flares to climate change (research paid by Carbon Fuels think tanks) and failed miserably. Only one of her papers was accepted by an accredited publication, and the review process was so flawed and the findings so incorrect that other scientists ... | [
"A plot from the IPCC comparing the various components of changes in radiative forcing: ",
"http://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-ts-5.html",
"If you really want to dig down, the best recent publication is the 2010 review article by Gray et al. ",
"http://onlinelibrary.wiley.com/doi/10.10... | [
"Your source is hardly unbiased, they are skeptical of anything that doesn't support AGW unquestioningly. ",
"\"Unbiased\" =/= \"Unwilling to call something out as false\". Just because the vast majority of garbage is on the denier side doesn't mean that any source that recognizes that fact is biased. Do you t... |
[
"Why are Uranus's moons equatorial?"
] | [
false
] | Assuming a protoplanet (or more) collided with Uranus, why would the moons change their orbital plane to match Uranus's equator? If they were there before the collision, how were they affected by the collision so that they moved so much? And if they were captured after the collision, why is it that they didn't stay in the ecliptic like pretty much every other moon or planet? I thought that maybe it had to do with a similar mechanism as that which causes tidal locking, but even that seems too extreme. I've been searching for a few hours, with no results. | [
"So first, let's get this out of the way: The idea that Uranus got knocked on its side by a severe impact early on is an old theory, and in the past 20 years this idea has strongly fallen out of favor. It turns out it's almost impossible to have an impact large enough to turn Uranus on its side that doesn't complet... | [
"the moons' orbits would have been brought into line by the gravitational attraction of the slight equatorial bulge caused by Uranus' rotation.",
"That's not really how equatorial bulges work on inclined orbits. They cause a ",
"regression of the nodes",
" (causing the orbit to wobble) as well as ",
"preces... | [
"Currently, how widely accepted is the Nice model? What, if any, are the most likely competing hypothesis?",
"Venus is the only terrestrial planet that lacks a moon. Could a moon loss scenario also apply there?"
] |
[
"Why is there a Voronoi diagram on my giant Reese's peanut butter cup?"
] | [
false
] | I just finished a class in computational geometry, and I bought a giant Reese's peanut butter cup at the grocery store and when I opened it up, I saw a familiar sight. There was what looked like a on the top of it. I took a picture and put in the coordinates of the pixels where the sites approximately would be into and the results matched almost perfectly. Here are the images of the peanut butter cup, the generated Voronoi diagram and them overlaid: Why would this be there? Do they use this in the manufacturing process? | [
"I think this math question has an engineering-flavored answer: the melted chocolate that they use to cover the peanut butter probably has a somewhat high viscosity. If all of the chocolate were applied in the center of the cup, it would take a while for all of it to spread evenly over the surface (and it would li... | [
"The reason is fairly simple. What is a Voronoi diagram? It's a diagram created by taking pairs of points that are close together and drawing a line that is equidistant between them and perpendicular to the line connecting them. That is, all points on the lines in the diagram are equidistant to the nearest two (... | [
"I would agree, except that the difference in color is from the variation in surface shear flow direction, not temperature gradient. Chocolate doesn't turn different colors depending on how fast it cools, but variation in the orientation of chocolate particles would definitely do it. Rheoscopic fluid would be an ex... |
[
"How is it proven that entangled particles don't have a well defined spin?"
] | [
false
] | In video Veritasium tries to explain this at 2:13 but I don't get it. He states that if entangled particles have a well defined spin (vertical and opposite) and are measured in a horizontal direction (perpendicular to the spin) there is a 50/50 change for each particle being spin up. And that this would give a 50% chance that both particles would have the same spin violating the law of conservation of angular momentum. I am totally missing the point here. Why would entangled particles having a well defined spin have a 50% change of both having the same spin and particles with undefined spin not? | [
"If the two particles had a well defined spin in the vertical axis, one being up and one being down, if they were measured in the horizontal axis they would each have a 50% chance of being measured spin up or spin down, independent of each other. For instance, if particles A and B had well defined spin in the verti... | [
"Particles with well defined spin cannot be entangled, for the reasons above. Entangled means they always give the opposite result no matter which axis they are measured on. If the two particles are not entangled but are simply opposite, you get the results I described in the first paragraph. As soon as you measure... | [
"Thanks for your answer. I understand what you say but the bit in the video about entangled particles with a well defined spin is still confusing to me. Are there any experiments done with entangled particles with a well defined spin like the experiments done with entangled particles with an undefined spin? Or is V... |
[
"Is it possible to control which direction heat flows on the atomic of molecular levels?"
] | [
false
] | Is there a material that can transfer heat in desired directions rather than just march towards equalizing temperatures between two objects? I don't have a background in physics or chemistry, I just had a curious thought after thinking about how well my Yeti cup keeps things cold. I'd love to learn more about our understanding of heat flow, and any cool efforts ongoing on the subject. | [
"Thermal conduction is the transfer of heat by collisions between particles and movement of electrons within a body. Heat likes to flow from higher energy places (hotter) to lower energy places (colder), and electrons and other stuff like to go where the ",
"free-energy (combination of energy and entropy) is lowe... | [
"Very informative thank you! "
] | [
"So could it be possible to make a structure at the atomic scale \"locking\" the atoms to only move in a two dimensional sense?"
] |
[
"If a pregnant mother drank enough to get drunk, would the baby as well be drunk?"
] | [
false
] | If the baby did not die, would it technically be drunk? | [
"The Alcohol enters the Mother through the stomach/intestines and is absorbed into the blood. The mother's circulatory system is ",
"not directly connected",
" to the fetus's circulatory system, as it is routed through the placenta and then through the umbilical cord. However, ",
"alcohol can permeate the pla... | [
"The placenta is about as permeable to alcohol in the blood as the blood brain barrier in the mother. The baby would have the same BAC as the mother, except the baby is much smaller, so the effects would be way more pronounced. On the other hand, it depends when in the pregnancy this happens, and I don't know how w... | [
"What?"
] |
[
"Is It True Helium Is a Liquid At 0 Kelvin?"
] | [
false
] | null | [
"Solid helium is quite cool. It's probably the solid with the least density, if you exclude aerogels and other composite stuff. It's density at 1.15K and 66atm is 0.2 g/cm",
" That's a fifth of water. And it's highly compressible, almost five times as much as water. The reason is that the zero point energy is so ... | [
"It freezes at higher pressures."
] | [
"What properties would solid helium have? This concept is hard to wrap my head around."
] |
[
"Do the points where a curve function and its derivative intersect hold some significance?"
] | [
false
] | We're doing calculus in school now. And I was wondering whether the points where y = y' are used in science, engineering or some field? Are they called something? I was wondering when I graphed a cube function and its derivative . | [
"Exactly. The function y=e",
" is its own derivative: the function's graph and its derivatives graph are the same, over the whole length of the graph from minus to plus infinity. And it is the ",
" function with this property.",
"BTW, if you want to get your jargon right: You wrote \"y=e",
" \", which descr... | [
"Thanks! That makes perfect sense. I just have a question here:",
"If some function y fulfills the differential equation y' = y, then we have that y = Ce",
" is the exponential function. This is used rather widely in applications.",
"So for the graph y = (c)e",
" , the answer of y for any value of x on the ... | [
"Thanks! That makes perfect sense. I just have a question here:",
"If some function y fulfills the differential equation y' = y, then we have that y = Ce",
" is the exponential function. This is used rather widely in applications.",
"So for the graph y = (c)e",
" , the answer of y for any value of x on the ... |
[
"how do molecules in cells know what to do?"
] | [
false
] | ive been reading a lot of biology and ect chemistry stuff recently, and in normal chemistry its like, ok, we've got a couple molecules in a jar, there's only a couple things they can do. and they do that. but in biology it seems like there's this infinite possibility for things to go wrong. oh, ok there's this DNA in this nucleus and there's this other thing that's gonna copy it, but how does it get there, and why doesn't it react with some other random molecule along the way? (not specifically that case, but as a general rule) | [
"It's because biological molecules fit together geometrically. The molecules in a cell are all careening around at random, but if they don't fit together, they just bounce off of each other. This continues until they find a match, and then some reaction occurs. Actually there are some molecules that fit into a lot ... | [
"The cellular molecules that I am going to address are proteins, specifically enzymes (proteins that are able to catalyze a reaction, i.e. they increase the efficiency of the reaction without being consumed by the reaction itself).",
"The short answer is that they do not actually \"know\" what to do. You have th... | [
"I feel ",
"Brownian motion",
" should be mentioned. It's tempting to anthropomorphise molecules as the combination of Brownian motion and varying levels of interactivity makes it seem like molecules seek each other out, but really, most molecules have bumped into most other molecules in the cell and some of th... |
[
"Is it possible to breen pedigree calves with non-pedigree calves?"
] | [
false
] | I got this question for school (it's rufly translated from dutch) and to be clear it's not about it being possible for pedigree cows and non-pedigree cows to have a child; it's about if it would be possible for a non-pedigree cow to have a pedigree cow/calve as child. If not as some sort of surrogate... Might this be possible in any way? | [
"I'm not sure about cows, but with cats, dogs and horses, the animal has to have pedigree ('pure') parents and grandparents in order to be called pedigree. The word 'pedigree' basically means 'family tree', and in terms of animals it's used to show that this animal has pure parents and pure grandparents, with no ot... | [
"All \"cows\" are the same species. They can have fertile offspring together. A \"pedigree\" cow (or any animal) is just one that has a record of lineage."
] | [
"to be clear it's not about it being possible for pedigree cows and non-pedigree cows to have a child"
] |
[
"Why do my feet feel like they're burning if I put them in warm water when they're cold?"
] | [
false
] | [deleted] | [
"I'm surprised no one has answered this already, as this question is fairly easy to answer. Your feet feel like they're burning because of the difference in temperature. The rest of your body doesn't feel that way since it is not as cold as your feet, as the difference in temperature between your body parts and the... | [
"I've thought this effect related to the involvement of \"cold\" thermoreceptors in burning sensations and that it was essentially a variant of the ",
"Thermal Grill Illusion",
".",
"Perhaps someone can elaborate or dismiss this."
] | [
"Found this on page 5 of ",
"Craig and Sorkin, 2001",
":",
"[...] there is a cross-modal interaction between\ninnocuous thermosensory (cool–warm) activity and C\nfibre-evoked pain. Therapeutic cold or warmth has a\nperipheral palliative effect on inflammation and on\nsensitized nociceptors; in addition, there is... |
[
"If I remember a song in my head, lyrics and all, does the brain use the equivalent amount of memory to store this as it would need in a device?"
] | [
false
] | [deleted] | [
"This is a difficult question to answer. And it's even quite difficult to explain why it is difficult.",
"Let me put this question to you. Pick up whatever is to closest to your right hand, say, it's a pen. How many megabytes is that pen? Is that a reasonable question to even ask? Plainly, it currently is not rep... | [
"There is at least one man who is able to imagine complex pieces of music with an accuracy level that was thought to be theoretically impossible until it was shown that he does it. He's an American Rag-Time concert pianist called Bob Milne. ",
"It's not just that he can 'hear' symphonies by imagining them, he's d... | [
"There is at least one man who is able to imagine complex pieces of music with an accuracy level that was thought to be theoretically impossible until it was shown that he does it. He's an American Rag-Time concert pianist called Bob Milne. ",
"It's not just that he can 'hear' symphonies by imagining them, he's d... |
[
"If a bird is inside a box, but it's flying, does the box weigh the same as it would if the bird was standing on the bottom."
] | [
false
] | I was staying with one of my buddies at his grandmothers house for a few days, and somehow we got onto this question. To me and my buddy, it seemed simple. If the bird is flying the box would weigh less because the weight of the bird is being supported by the bird itself so it's not combined with the weight of the box. | [
"If the box is closed (no air coming in or out) then the box will weigh the same on average regardless of whether the bird is flying. Over a long period of time, the average acceleration (averaged over time) of all the mass in the box (bird, air, and box) is zero, which means that the forces sum to zero (averaged o... | [
"You are correct. This is one of the reasons why beaverjacket's answer has \"averaged over time\" everywhere in his answer. The lift birds create is rather variable, and what will likely be turbulent airflow inside the box only makes this worse."
] | [
"Let's say you have a tall box with a bird in it... if the bird is increasing its height, does the box begin to weigh more during it's climb?",
"I imagine: bird hovering = static downforce = opposite of weight of bird. So equilibrium.",
"But if the bird is climbing, they're exerting a downforce more than they'... |
[
"Is there such a thing as negative water pressure? has it been studied?"
] | [
false
] | I got this question by pondering Luke Skywalker suspended in some kind of water tank while convalescing ( ). You know when you're in the tub with a cup, and you completely submerge the cup, filling it with water (no air) and then turn it upside down and raise the bottom of the cup above water level? It would seem to me that there would be some kind of negative water pressure in the cup. Imagine doing that on a massive scale, in a large swimming pool. When I dive down 10+ feet in a swimming pool, my ears start to hurt from the pressure. If, in such a pool, there were a similar inverted, giant glass - sealed at the top - filled with water (that is, the water is in the glass only because of vacuum, like the bathtub cup) that rose 10+ feet above the surface of the rest of the water, what would it feel like to swim up in it? Would my ears hurt just as much, except in the opposite direction? Are there any possible therapies or treatments or scientific phenomenon that occur, or occur more readily, in such a vacuum like, negative water-pressure environment? Have there ever been studies or research conducted in this direction? | [
"It would seem to me that there would be some kind of negative water pressure in the cup.",
"No, the pressure just goes below the atmospheric pressure.",
"Would my ears hurt just as much, except in the opposite direction?",
"It would feel a bit like in an airplane that rises rapidly. Yes, the ears could hurt ... | [
"If you try to make the column of water too high, you reach (nearly) zero pressure at about 10 meters",
"Presumably swimming upwards into a sealed tube 10 meters high with a vacuum at the top would have nearly the same effect as jumping out of the airlock of a space ship. Except that the void at the top would be ... | [
"Remember that you can't really have negative pressure. You can have a negative relative pressure, where something is at a lower pressure than some other arbitrary zero point, but you can't have the absolute pressure be less than zero, it's just not possible. ",
"EDIT: You can have negative pressure! In liquids a... |
[
"Why is the moon not spinning?"
] | [
false
] | null | [
"An orbiting object not spinning like that is called \"tidally locked\". If you search this subreddit for this keyword you should find a lot of explanations on how it works. This is not unique to the moon."
] | [
"tidally locked",
"Thanks for the explanation. I just read about tidal locking, I didn't know it is called that. ",
"Wow, this theory makes zero sense. It seems another one of those weird explanations that humans come up with when they have no explanation (pyramids, evolution, gravity, supernatural etc.). It sa... | [
"There is a lot of missconceptions in your comment. The moon is definitively affected by Earth gravity (as well as the opposite). Tidal locking is a fairly straightforward consequence of Newtonian gravity on non-symetrical bodies. ",
"Satellites are definitely affected by earth gravity, this is why they orbits th... |
[
"Does electricity slow down as it moves along a wire (or other conductor)?"
] | [
false
] | If you use a generator and have a wire running from it, would there be a point at which the wire was too long to be useful? Could you run a generator in New York and power a lamp in LA? Does it slow down, peter out, and if yes to either, why? | [
"The main issue with long distance power transmission is that you don't get 100% transmission. A lot of electricity is lost to heat (and other energy) as the electricity moves down the wire.",
"Our grid isn't very efficient, and this is one of its big problems."
] | [
"It seems that by \"slow down\" you mean \"get weaker\", is this correct?",
"The main issue affecting long-distance electrical power transmission is voltage drop due to the resistance of the wire. If this voltage drop is too large it will affect the equipment trying to draw power from the line. "
] | [
"can you expand on (and other energy)?",
"I understand loss of energy through heat (non-perfectly insulated wires, transistors, etc)"
] |
[
"How exactly do physicists interpret line integrals of vector fields?"
] | [
false
] | First of all, please forgive my poor physics-knowledge. I was told that physicists use line integrals quite often, and when I searched for examples, I found the following several times: "For example, the work done on a particle traveling on a curve C inside a force field represented as a vector field F is the line integral of F on C." (From Wikipedia) This, however, I don't quite get. For example, let V be a vector field and C a curve parametrised by a function r in such a way that V(r(x)) is orthogonal to r'(x) for all x. Then the line integral of V on C is equal to 0 - but speaking from a physical perspective, I'd still have to apply a force to a particle to move it along its path C through V, wouldn't I? Please show me my mistake! | [
"I'd still have to apply a force to a particle to move it along its path C through V, wouldn't I?",
"Nope! Or, at least, an arbitrarily small force would suffice. The point is that the vector field would not be doing to work to stop you. This is analogous to pushing a box along a horizontal, frictionless surface.... | [
"The integral along C doesn't tell you the force needed to move the particle along C, but rather how much work the field V does on the particle as it moves along C. If the field and the path are always orthogonal the field does no work on the particle as it moves, which tells you that as you move the particle aroun... | [
"Gravity is a conservative vector field - consider the Earth's orbit around the sun. It keeps going around and around the sun and coming back to the same place every year. No work has been done on the Earth at all during this time."
] |
[
"Why was Bismuth, Antimony, and Arsenic discovered so early in the history of Chemistry?"
] | [
false
] | I read the other day that they were all discovered before the 14th century, and I'd just like to know why. Chemistry at that time wasn't very advanced, it was just beginning thanks to Alchemy. Even phosphorus and Nitrogen were discovered really early, compared to the rest of the elements on their respective period. So why was that group's elements discovered so soon, and how? | [
"The scientists at that time looked at a bunch of minerals and heated them up or reacted them and eventually some interesting things came out. Arsenic can be isolated by heating the mineral arsenopyrite. The arsenic is driven off in gas form and can then be captured.",
"Antimony sulfide was well known and ",
... | [
"Thank you!"
] | [
"If you don't get an answer here, you can try ",
"/r/askhistorians",
", ",
"/r/historyofscience",
", or ",
"/r/philosophyofscience"
] |
[
"Global Warming: Sea Level Rise of 50cm. What is the big deal?"
] | [
false
] | First off, I want to make it clear that I am not a global warming skeptic. I know that 97% of scientists agree with AGW. I understand the issues with temperature increase and how it affects ecosystems. I understand the issues with ocean acidification. But I simply do not understand why a sea level rise of 50cm by the end of the century is a big deal. I live next to the coast and I have been to the beach many times. There is usually a couple of meters high worth of sand from the point where I park my car to the water level. If the water level rose by 50 cm over the course of a century, I probably would not even notice it. | [
"It causes damage to lots of areas close to the ocean and damages freshwater habitats near to the shore.",
"The temperature rise is perhaps more significant, as are the effects on weather."
] | [
"This is exactly it. Both parts of the concern.",
"Assuming the water is coming from melting polar ice caps, you're going to see some serious fluctuation of ocean currents, which is large responsible for governing weather, particularly on areas near the coast."
] | [
"Half a meter is a very big deal if your regions's altitude is close to sea level. Half of the Netherlands, for example, is only one meter above the current sea level. Hurricane Katrina shows you what can happen to areas like Louisiana. Many pacific islands are equally close to the sea level and many, many people l... |
[
"If someone receives a donated organ, can that organ be donated again when they pass?"
] | [
false
] | null | [
"Not an expert here, just a doc.",
"I have never heard of that thing happening so I guess there are reasons for it not being practical.",
"One I can think of is that once you operate in a person, his/hers organism, trying to put things back, makes a lot of connecting tissue where you disturbed it, so taking thi... | [
"I heard that donated organs only last so long because of damage to the organ builds up over time due to slow chronic immune rejection of the organ, so maybe that's why. I wonder if someone who recieved a transplant and died in a car crash a week later could still donate though."
] | [
"I work with a few doctors and nurses in a kidney and liver transplant team. Never heard of a liver being replanted however it is possible to reuse kidneys. \nThat being said, it would only be taken if the patient receiving the kidney had almost immediately passed away, before any long-term use occured. \nTake this... |
[
"The past never ceases to exist? If so, this means that, in someway, we never cease to exist too, am i right?"
] | [
false
] | (pardon my english, not a native speaker) | [
"This thread is oddly void of meaningful information."
] | [
"This is one of those questions that — deliberately or not — takes advantage of subtle ambiguities of language to give the impression of meaning where no meaning exists. A Buddhist would say that the only possible meaningful answer to the question is \"mu.\"",
"That said, I have this big, empty box in front of me... | [
"I suggest you try asking the people in ",
"/r/Philosophy",
". Scientists are reluctant to answer this type of question because there is no clear answer and no real way to test whatever answers you can come up with. ",
"/r/Philosophy",
" is quite a good subreddit. ",
"Good luck!"
] |
[
"Imagine 2 spheres weighing 1g each, 1cm in diameter, and placed 1m apart in space..."
] | [
false
] | Assuming no other outside forces, how much time would it take for gravitational force to cause them to eventually touch? I am sure there is probably very simple math for this. Please help a dumb artist! I've posted this question several times and don't get any responses... | [
"Unfortunately the maths isn't very simple; you get a nonlinear second-order differential equation as follows:",
"F = Gmm/r(t)",
"F = 2ma = 2mr''(t) (the 2 comes in because the force is applied to each sphere, so the relative acceleration is doubled)",
"-> r''(t) = Gm / (2r(t)",
" )",
"with the boundary c... | [
"If we use them as point particles instead of 1 cm spheres, you can use the ",
"free fall equation",
" to calculate it, and get 3.04 million seconds, or 35 days, 4.5 hours."
] | [
"This is not an exact calculation, but they would exert an initial force of 6.7x10",
" N. Which means the acceleration would be something like 6.7×10",
" This is where I get fuzzy. That acceleration will change as they get closer to each other, but for a ballpark, it would take about 3x10",
" to accelerate... |
[
"Why is Helium not commonly used for inert atmospheric reactions?"
] | [
false
] | null | [
"heavier than air gasses are preferred as they can be contained, utilized, and reclaimed far easier than lighter than air gasses....",
"\nThe expense is negligible for most operations. My kid brother goes through a tank of argon every month or two welding.. Id have to say Argons MORE readily available than helium... | [
"Argon is like 1% of air, it's massively more available on earth and essentially renewable. Helium floats high and awat."
] | [
"Weight and cost. Helium is much lighter than air, so in the atmosphere, you’ll lose most of it before it reacts. Nitrogen is commonly used for preservation because it about weighs the same as air. With that it is much more commonly produced "
] |
[
"What actually are the 'impurities' that allow flux tubes to penetrate superconductors, achieving Flux Pinning?"
] | [
false
] | I was curious about the process of Flux Pinning, and found that thin flux tubes from a magnetic field actually the superconductor itself, locking it in place, almost. However, I couldn't find any information on how or what these impurities are or come to be. Are they just small holes? I'm not sure if this is too mundane a question to answer, but I find the whole subject of Flux Pinning fascinating. I'm a Physics (British definition of) college student, so I'm essentially a layman, haha. Thanks a lot. | [
"According to the ",
", ed. Walter Benenson, John W. Harris, Horst Stöcker, Holger Lutz, ",
", places at which the magnetic flux tubes in type-II superconductors may be fixed. Such pinning centers may be dislocations, grain boundaries, or segregations, i.e., defects in the crystal lattice."
] | [
"Hm, didn't know about Google Books! Ah, so it could really be anything that flux tubes could penetrate? Even grain boundaries ",
"? That's quite interesting. Thanks a lot, I might pick up the book, so thank you also for linking it."
] | [
"Even grain boundaries (presumably in wood?)?",
"Wood isn't superconducting :).",
"The individual crystals that make up your typical multicrystalline sample of metal or ceramic are called \"grains\". That's what it means by grain boundaries."
] |
[
"How \"bright\" is WiFi?"
] | [
false
] | Assuming you could convert 100% of the amount of energy that the signal contains and convert it entirely to a certain wavelength of visible light how would that compare to a common bulb or led? Please consider a home series wireless N variety access point, and if possible give us a comparison to a lightbulb, christmas light, etc. | [
"FCC regulation is that output power be less than 1 Watt. Typically it is less, about 100 mW. For comparison, a typical ",
"LED",
" is about half that, around 50 mW, and a standard 60 W incandescent puts out about 1 W of visible light. So a standard WiFi router would look like a low-wattage incandescent or a br... | [
"Great answer! Another interesting point is that a wifi photon has about 100,000 times less energy than a visible photon, so while a power meter will show less power than a typical lightbulb, if you had a microwave photon counter, it would show dramatically more photons being emitted than from a lightbulb."
] | [
"It's really not, though. When you build a laser, you don't say \"this one's going to shoot 10 photons per second, better make them high-energy photons!\". You say \"I'm going to put in 1 kW, better make sure as much of this power as possible makes it to the target!\"",
"High-energy photons get absorbed more easi... |
[
"Benzene is a known carcinogen. Why is it that by adding just a methyl group, toluene is not carcinogenic?"
] | [
false
] | [deleted] | [
"The big difference is metabolism. Benzene is metabolized, to a small extent, to a reactive epoxide that can alkylate DNA (likely via the sort of intercalation mentioned by ",
"u/croutonicus",
"). Toluene, though, is very easily oxidized on its methyl group to benzoic acid, which is excreted harmlessly through ... | [
"Toluene has the same basic shape as benzene, the methyl group is not big enough to prevent van der waals interactions with aromatic DNA bases."
] | [
"Neither benzene nor toluene are stable enough in vivo to interact directly with DNA, it is their metabolites that show differences in DNA intercalation."
] |
[
"How do physicists separate neutrinos from particle collisions from neutrinos coming from the sun?"
] | [
false
] | How are neutrinos from high energy particle collisions separated from the thousands of neutrinos that would pass by from the sun? I know that neutrinos are detected using conservation of momentum, but wouldn't neutrinos that pass by from the sun alter the momentum of the collision? | [
"Well, most neutrinos that are detected do come from the sun. If you're referring to experiments that use man-made neutrinos (so to speak), then they employ highly anisotropic detectors, meaning only neutrinos coming from a specific direction can trigger the detector. It's also necessary to measure the background f... | [
"Most of the neutrinos created in collider experiments have a much higher energy than those emitted by the Sun. The Sun emits neutrinos of energy 10 MeV or less. Also, detectors have directionality. They can detect which direction the neutrinos are coming from. As far as the collider experiments are concerned, neut... | [
"How do you design an anisotropic detector for neutrinos? I'm only familiar with the \"put a giant tub of water deep underground\" sort of detector."
] |
[
"Why are the air intakes of fighter jets so often on the bottom of the plane?"
] | [
false
] | Just as an example, the F-16 is like a vacuum cleaner, and will suck up ANYTHING off the ground nearby. That's a problem when rocks, tools, and bolts, get sucked up into the air intake, so I'm wondering why they continue to be below wing level. As I'm not an aeronautical engineer, the only good reason I can think of so far is to have the cockpit out from in front of the intake. Is there more to it? | [
"For fighters, having the intakes above the wings would create a visual obstruction for the pilots, a definite disadvantage in a dogfight. Generally, the top of the wing is more aerodynamically sensitive than the bottom and stalls are caused by flow separation between the air stream and the top of the wing, so you ... | [
"I'd like to add to this answer. ",
"Most of the American (well most of the planes) have intakes below the plane. But good ole Russian planes (MIG 29) have 2 intakes. ",
"One above the plane one below",
". These help in taking off on runways with debris on them as the intakes won't suck up anything on the gr... | [
"On a serious note though I imagine it would be quite useful to save time having to sweep debris from a warzone runway that's been attacked, or be able to use a dirt/gravel improvised runway."
] |
[
"[Physics] How does the the Beta function describe the strong nuclear force?"
] | [
false
] | I've always wondered what were the mathematical laws that describe the strong and weak nuclear forces. I was watching the Elegant Universe and it said the Beta function describes the strong nuclear force. Can someone explain the physics of how the describes the strong nuclear force? | [
"The other two commenters saying that you are confusing it with the Callan-Symanzik beta function are mistaken; the ",
"Veneziano amplitude",
" really ",
" the Euler Beta function.",
"In particle physics we are interested in calculating scattering amplitudes. These are functions which, given a set of incomi... | [
"I think you're confusing it with a different kind of beta function: ",
"http://en.wikipedia.org/wiki/Beta_function_(physics)"
] | [
"As iorgefeflkd pointed out, the beta function you've linked to is not the same beta function as is referred to in particle physics. In fact, every quantum field theory has a beta function, even quantum electrodynamics, but it is particularly relevant for understand the strong nuclear force, or more specifically qu... |
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