title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why do carbonated beverages lose carbonation faster when stored at room temperature after opening as opposed to being stored in a refrigerator after opening?"
] | [
false
] | [deleted] | [
"Gases are more soluble in a liquid at lower temperature, so as the temperature rises, the gas becomes less soluble in the liquid, driving it out of solution.",
"For the record, the inverse is true for solids, they are less soluble in liquids at lower temperatures, so you can dissolve more salt or sugar in a solu... | [
"Of course. I'm sure in that case acid-base equilibrium plays a role? "
] | [
"That is a really good question. Acid base equilibria must play a role, and is probably related but I don't think it's the reason per se. Ammonium carbonate has an endothermic dissolution but again that's related to why but it's not exactly why, as plenty of other salts with endothermic dissolution are more solub... |
[
"Could we make synthetic honey using the same methods bees do but on a larger scale?"
] | [
false
] | With the same enzymes and ingredients and stuff, of course. And would it taste the same as real honey? | [
"http://en.wikipedia.org/wiki/Nectar#Natural_components_of_nectar",
"it doesn't seem to be so simple",
"some things produced biologically are very difficult to produce in other ways, like silk."
] | [
"http://en.wikipedia.org/wiki/Nectar#Natural_components_of_nectar",
"it doesn't seem to be so simple",
"some things produced biologically are very difficult to produce in other ways, like silk."
] | [
"Going off what you have, you also have to take into account of how pollens can affect flavor. Since there is most likely more types of pollen than there are chemicals in nectar, it would be hard to duplicate. ",
"Then there is perhaps the factors of the nectar being inside the bee and the honey comb, which can i... |
[
"Is it possible to integrate by parts with more than 2 parts, and if not why not?"
] | [
false
] | null | [
"Yeah, you have to iterate the process though. You could try deriving a formula for it using the product rule on 3 terms, like compute (fgh)', manipulate and integrate, but that formula will be messy to deal with.",
"Also it's math, so I mean you can do this yourself. Try integrating x/(1-x",
" by factoring and... | [
"Any way that we could use it can be reduced to the typical integration by parts. The three-term product rule is (fgh)` = f'gh+fg'h+fgh' So if we have something of the form f'gh, then we could rewrite it as",
"f'gh = (fgh)' - fg'h-fgh' = (fgh)'-f(gh)'",
"Put G(x)=g(x)h(x), then this is just f'G = (fG)'-fG', whi... | [
"usually you'll do something like int ugh = int u(gh)\nand then have u as a derivative f' or something like that.",
"keep in mind that the method relies on you knowing how to antiderive some of the factors, so since",
"(fgh)' = f'gh + fg'h + fgh'",
"int f'gh = fgh - int(fg'h) - int(fgh')",
"begs the questio... |
[
"Does anyone know how long it will be until we lose contact with the Voyager space probe?"
] | [
false
] | Does anyone know roughly how long it'll be until we lose contact with Voyager, or at least the distance becomes so great that the time between when it sends the signals and us receiving them makes it useless? | [
"At the latest, about 2025. At this point, the on-board power source will have decayed to the point where the probe can no longer operate its instruments. Even if contact could be maintained past here, the probe would be unable to gather any new information to transmit to us, so it's as good as having lost contact ... | [
"Even if it can only transmit and receive, we can still get time delay ie. distance (and therefore speed), which could give some information about the density of whatever it's passing through... but that's a bit of a stretch.",
"Edit: Actually there are more direct ways of measuring speed via Doppler shift. Some ... | [
"I seriously doubt that it would be possible to detect Voyager with current radar capabilities. Radar detectability goes as 1/r",
" , and from glancing at ",
"this",
" page it seems most of the asteroids we've been able to do radar on are at least hundreds of meters in diameter, and are not more distant than ... |
[
"Creating radio or light waves by spinning a magnet?"
] | [
false
] | Maybe my Google is failing me, but something I always wondered. Since radio/light waves are forms of electro-magnetic radiation, is it possible to, for example, create a 500 kHz radio carrier wave by spinning a magnet at 500 thousand RPM? (physics of actually spinning one that fast and keeping it from falling apart a... | [
"I think you meant 500K RP",
". But setting that aside, if you could \"theoretically\" spin such a magnet, then you would be creating radio waves. Changing magnetic flux produces electric fields. If your movement is sinusoidal, then you will create a similarly varying electric field which is what we call EM ra... | [
"Ok, so if you run a magnet back and forth over a wire at X times per second, you will then cause the wire to emit a radio wave at X Hz then?"
] | [
"Radio waves have to do with Electro magnetism so spinning a magnet would probably not do much, unless there was a wire near by where the electrons would be affected by the change in magnetic field, and move at the same frequency. ",
"I guess theoretically almost everything is a tiny bit magnetic so you would be... |
[
"If diamond is the hardest mineral, is it also the most stable to weathering process?"
] | [
false
] | null | [
"There are two things to address in the question - what is hardness, and what is weathering?",
"Hardness is simply the ability of a material to resist being scratched. Diamond is currently the hardest known material using this definition, only being able to be scratched by another diamond. This does not mean it i... | [
"Diamonds also slowly decay to graphite. Graphite is more stable than diamond, so it's structure will slowly become more and more graphite. I don't know if it's THE most stable. It won't be withered away, but it can still break into smaller pieces quite easily."
] | [
"Doesn't turning a diamond into graphite take billions of years at normal temperatures/pressures? That's insanely slow, even on geological timescales."
] |
[
"Does UVA (long-wave ultraviolet) light behave more like visible light than higher-energy ultraviolet light?"
] | [
false
] | It seems to just be an evolutionary accident. UVA light scatters far more easily than visible light (especially in water, so our aquatic ancestors had no need to evolve UVA light receptors). Furthermore, UVA light doesn't stimulate electrons in the way that UVB and UVC light do. | [
"All the distinctions along the electromagnetic spectrum are arbitrary. The essential nature or behavior of a photon doesn't depend on its energy.",
"We call visible light \"visible light\" because it's, well, "
] | [
"All light \"behaves\" the same, the only difference between different parts of the EM spectrum is the wavelength. ",
"UVA is at the lower range of visible light (~300-400 nm) so, if your question actually is \"Is the response of matter to UVA light more similar to visible light than UVB (280-315 nm) or UVC (100-... | [
"Okay that's true. My question, though, was really this: could UVA be more appropriately categorized as visible light (we would have to create a new name for the band, of course) if it weren't for this evolutionary accident? ",
"There seem to be non-arbitrary differences between X-rays and gamma rays, between X-r... |
[
"If tomorrow I came up with a way to algebraically solve any nth order, nonlinear differential equation, what would we be able to know that we do not now?"
] | [
false
] | null | [
"we would know that you have made a mistake, because we have already proven that it is not possible (so as mathematics goes it is a fact now for all time, and will never change).",
"these don't have algebraic solutions:",
"du/dt = u² + t",
"du/dt = u³ + t"
] | [
"This is a very interesting question with a not very simple answer. The issue is that we can often solve such equations numerically, (at least for small systems), and thus any PARTICULAR (small) system we can also get an accurate number out. However, numerics is a black box, and only answers the exact question a... | [
"no, OP claimed ",
" solutions. the source where i got these from said the first one can be solved by airy functions (which are basically integrals of cosines of polynomials) and it said for the second one you can write down a solutions in terms of a power series. "
] |
[
"\"Light from the void\" How do SQUIDs act like turn-table mirrors?"
] | [
false
] | I was reading through this article and it mentioned that they used a SQUID to act like a mirror to give virtual photons momentum so that they became real photons. How does this actually work? All they used was a metaphor to describe the process. | [
"Correction: tunable mirror*"
] | [
"You can read the preprint of the actual work on the ",
"arxiv",
". The introductory section describes the device itself:",
"\"[The device is] an open transmission line terminated by a SQUID. The SQUID acts as a parametric inductor whose value can be tuned by applying a magnetic flux through the SQUID loop. ... | [
"Yes it does, thank you."
] |
[
"if you cut someone's lips, and held them closed for an extended period of time, would they heal closed, or just heal normally?"
] | [
false
] | null | [
"This question has been asked a few times. I'll summarize the responses. Basically, they would heal together. When you first start the process a blood clot will form bridging the gap between your lips. This clot will be replaced by collagen type III (found in scabs). This collagen will ",
" be replaced by collage... | [
"Anecdotes, layman speculation, off-topic jokes, memes or medical advice is my guess."
] | [
"Anecdotes, layman speculation, off-topic jokes, memes or medical advice is my guess."
] |
[
"Is there a difference in cancer rates between 1st world and 3rd world countries?"
] | [
false
] | I know population would make more cases in one area but I want to know based on population if there is a difference in % of people that get cancer in 1st vs 3rd world countries. | [
"A major complication in this is that developing countries have significantly higher mortality from diseases that are either eradicated or very easy to treat in developed countries (especially infectious diseases). This means that many people in developing countries die of other diseases before they can get cancer... | [
"Variations in cancer rates by geography have more to do with local exposure to carcinogens than first-world or third-world status. As an example, gastric cancers are more common in Japan than the US. This is thought to be because of a preponderance of smoked fish in the Japanese diet. Interestingly, if a person of... | [
"The simple answer is yes. Other commenters have explained why so I'll just give you the official figures;\nThere were 268 cases of cancer diagnosed per 100,000 in more developed regions, compared to 148 in less developed regions in 2012.",
"1",
" So thats around 66% more in developed countries, although as ",
... |
[
"How legitimate is the technology showcased in this Vice video that transforms CO2 into a carbon-neutral source of fuel for existing vehicles?"
] | [
false
] | If it sounds too good to be true, it probably is. But nevertheless, what's your opinion? Do you think this technology is legitimate? If it is, how likely / soon would it be implemented across the world to finally bring greenhouse gas emissions under control? This sounds like a huge turning point in the fight against ... | [
"Carbon sequestration and the production of artificial fuels are perfectly legitimate. It can be done and it has been done. In fact, producing artificial fuels from atmospheric carbondioxide is, in my opinion, one of the main requirements to significantly affect net carbondioxide emissions across the globe. Because... | [
"What goes up must come down, and you can't get something for nothing. The usual scientist's objection to synthetic fuel technology is \"it's possible but it takes a lot of energy\", which doesn't sound so bad, but that answer obscures the real problem: ",
".",
"So you need a big energy source, and unless you ... | [
"Another thing to note is that there is no particular reason to base artificial fuels on carbon / CO2. By using CO2 you first remove CO2 from the air, but by using the fuel you again return the CO2. If you don't base your fuel on carbon you don;t remove any CO2, but you also don't emit any CO2, so the net result is... |
[
"Mars, Europa, Titan - what is the most habitable place other than earth in the solar system? Is it realistic that we could colonise it, or find life? And finally, what about Gliese?"
] | [
false
] | [deleted] | [
"Sorry, I just didn't feel like sourcing it. Here you go:",
"liquid water and ice thickness:",
"Schenk, P., Thickness Constraints on the Icy Shells of the Galilean Satellites from a Comparison of Crater Shapes, Nature, Vol. 417, pg. 419-421, 2002",
"Tyler, R., Magnetic remote sensing of Europa’s ocean tides, ... | [
"There's a lot of debate about this question among planetary geologists. Personally, I think Europa may very well have extant life present on it. Europa is covered in ice, but it is a relatively thin layer (again, some debate here, but it's looking like it's less than twelve km) and it has liquid water underneath i... | [
"Another thing to consider is while the surface of Venus is very inhospitable, ",
"a large structure filled with breathable air would actually float in the dense atmosphere",
", and at an altitude of 50km the conditions are very earth-like, with a temperature range of 0-50 degrees C and a pressure of 1 bar."
] |
[
"How much longer does a second last for someone on Earth compared to someone floating in outer space?"
] | [
false
] | If I understand it correctly, the fastest you travel through space the slower you travel through time, and time also goes more slowly as the gravitational force acting on you increases. So is it possible to calculate the amount of time dilatation we are undergoing on Earth? | [
"The time dilation factor between an observer on earth and one in deep space who is stationary with respect to the sun is tiny. There are three contributing effects:",
"The relativistic time dilation factor is 1+1.55x10",
". The difference in the passage of time due to this factor is almost negligible - ",
"A... | [
"That's impossible. The reverse works though. For one second for someone not on Earth to be two seconds for someone on Earth, they need to be moving at (√3)/2 c, which is about 87% the speed of light, be in a gravitational field that has that escape velocity, or some combination thereof."
] | [
"You'd need to be one third the Schwarzschild radius away from the event horizon. At least, if you're using the kind of cheating measuring system that lets you measure the radius of a black hole with distance instead of time. If I'm doing the math right, or rather telling Wolfram Alpha to do the math right, the pro... |
[
"What do you think is the coolest mystery that science still can't fully explain, and if you're an expert in the field, what's your theory for it?"
] | [
false
] | null | [
"You should post this in the suggestion thread for the weekly discussion thread since it is not appropriate in general."
] | [
"Gotcha. Sorry, I'm a little buzzed and it seemed a good idea at the time."
] | [
"I think it's a good idea and you should suggest it in this thread: ",
"http://www.reddit.com/r/askscience/comments/wtuk5/weekly_discussion_thread_asking_for_suggestions/"
] |
[
"Can neutrinos pass through neutron stars like they pass through earth?"
] | [
false
] | [deleted] | [
"The density of a material affects how likely a neutrino is to interact. Neutrinos interact via the weak force, and only the weak force. The weak force is so named because of the relatively weak nature of the force. The interaction is also dependant on neutrino energy. ",
"At energies characteristic of beta decay... | [
"By exotics, I mean things with charmed, strange, bottom, or top quarks or tau leptons or muons. Things that intrinsically decay, because of mixing through the weak force with lighter states.",
"As for a good book... I dunno... I've just had this stuff thrown at me enough ways, I sort of remember it. Trawl throug... | [
"By exotics, I mean things with charmed, strange, bottom, or top quarks or tau leptons or muons. Things that intrinsically decay, because of mixing through the weak force with lighter states.",
"As for a good book... I dunno... I've just had this stuff thrown at me enough ways, I sort of remember it. Trawl throug... |
[
"Do vibrations in a wing affect the way the wing creates lift/downforce?"
] | [
false
] | null | [
"If it is more flat on the forward stroke and more vertical on the backwards stroke, it will push the helicopter forward",
"This is not how helicopters gain forward momentum. This kind of cyclic control will roll a hovering helicopter, and only very very negligibly impart any kind of forward momentum."
] | [
"Seeing as you posted under the Biology heading, I assume you are referring to birds and other flight-capable creatures.",
"If you are referring to the flutter of, say, an eagle's wingtip feathers, the short answer is no. While the angle of attack varies significantly, the flutter is so rapid that it averages ou... | [
"Hmm actually I didn't even put a heading sorry. I'm speaking more mechanically like on an airplane or race car. But thank you for the answer much appreciated"
] |
[
"Is all history on Earth traveling through space?"
] | [
false
] | My understanding is that the further we peer into space, the farther back in time we view, since light from further bodies in space take longer to reach us. And so, with deep space telescopes, we are in effect able to gaze backwards towards the beginnings of the universe. This got me wondering about our own planet. Is ... | [
"Not really, no. Inverse-square laws and all that. Light propagates outward in a sphere, and the area of a sphere goes with the square of the radius. So the intensity of light drops with the square of the radius. Before you get very far, in cosmic terms, the light is far too faint to allow anything to be resolved."... | [
"As Dimpl3s said, in order to go out far enough to look back at earth, you'd have to overtake the light travelling outwards from Earth and, to steal a phrasing from RobotRollCall, \"faster than light\" is a collection of words that doesn't have any meaning in our universe.",
" supposing there's some Alien intelli... | [
"Don't our television broadcasts become so weak after a certain distance of transmission that they are indistinguishable from background noise?"
] |
[
"How does chemotherapy treat tumors without destroying other cells in the body?"
] | [
false
] | [deleted] | [
"Standard chemo generally tries to target rapidly dividing cells, since cancerous cells tend to undergo a lot of mitosis. They can do this through a number of mechanisms, such as inhibiting DNA synthesis (methotrexate), disrupting DNA (cyclophosphamide), or inhibiting microtubules (paclitaxel). Of course, there a... | [
"Classical chemotherapy such as cisplatin targets rapidly dividing cells. Cancer is a disease characterised by excessively dividing cells, so cancer is hit by chemotherapy. The body remains largely unharmed because most cells in the body actually divide very rarely, if at all. However, those cells that do, are hit ... | [
"For a variety of reasons, cancer cells are not as efficient as healthy cells at repairing certain types of damage. For example, the vinca alkaloids such as vincristine and vinblastin inhibit microtubule polymerisation, which halts cell division in metaphase. At metaphase, cells have have two sets of chromosomes, n... |
[
"When someone has an allergic reaction, such as from being stung by a bee, what exactly is going on?"
] | [
false
] | null | [
"This type of allergic reaction is called a type 1 hypersensitivity. To break it down for you, we have 4 main cell types involved and a few main chemical messengers. First the bee venom, or antigens, are captured by antigen presenting cells (dendritic cells). Think of them like the body's surveillance system for fo... | [
"Bee venom contains proteins, which are foreign to your body. If your immune system recognizes a foreign protein, it can trigger a response to that protein. How the immune system responds will depend on the nature of the foreign protein, the individual's exposure to that protein in the past, their genetics, and man... | [
"I don't think this could have been explained with any more detail. Thanks, very informative!"
] |
[
"Can an archive file be smaller after unpacking?"
] | [
false
] | null | [
"Definitely - if you compress data that's totally incompressible. When you compress a file, the archiving program will store metadata (headers) that tell it how to unpack the data. If you can't actually make the data any smaller, then you'll be left with the same size data as before plus the metadata, giving you a ... | [
"No, they aren't. Mostly files that are coded to be small, so videos, music, images usually aren't compressible.",
"Just imagine that codecs try to make the files as small as possible, so they use basically every compression algorithm available to get the files as small as possible."
] | [
"They're still almost certainly very compressible, we just don't have the tools yet to do so effectively.",
"Compressibility is, in many ways, the same thing as randomness. See ",
"this layman-readable article",
" by Chaitin, for example. Any time your algorithm can look at data and say \"Hey, that's not gibb... |
[
"Is the flu \"more deadly\" this year in the sense that if you contract it, you have a higher chance of dying than in a normal flu season?"
] | [
false
] | A friend of mine is over 65 and is concerned about the news reports that this year's flu is "especially deadly". While I understand that the elderly are always at risk, in what way is this year's flu more deadly? Is there something inherent about the flu this year (other than the problems with the vaccine) that makes... | [
"The major problem with flu this year is that the vaccine wasn't effective. The yearly vaccine is a combo of three strains of flu experts have predicted will be major that year. If the prediction ends up wrong, an unvaccinated strain can spread. This is most dangerous for older people, who have a higher chance of c... | [
"I'd like to note that the early reports about the flu vaccine this year being less effective than usual were based on the southern hemisphere flu season. The strains active in Australia during our summer are not the same as the strains that will be active in North America over our winter.",
"According to the ",
... | [
"Also very young children."
] |
[
"How violent/rapid was the separation of Pangaea?"
] | [
false
] | Hi all, I am wondering how the first few moments would have played out when Pangaea broke up. Was there an almighty quake followed by a dramatic split? Or was it a small split of just a few centimetres that accelerated slowly? Would there have been a point where there was literally a few centimetres separating the cont... | [
"Explained in very simple terms: Look at the Afar region of East Africa as a modern day example. It is a very, very slow process that takes millions and millions of years. There is no ‘crack’ as you might visualize it - it’s more of a slow spreading apart, like taffy getting pulled. Eventually it gets so thin that ... | [
"Continental rift zones exist today and give you a good idea what things would have looked like in the early stages.",
"",
"https://www.nationalgeographic.com/news/2018/04/east-african-great-rift-valley-crack-spd/"
] | [
"On a sorta side note, the Gulf of California is actually a spreading center right now. The Baja Peninsula is being pushed away from North America and a new “ocean” is being formed."
] |
[
"If I'm playing my music at a volume of 8/10, would that use up my battery faster than if I played the music at 3/10?"
] | [
false
] | Does playing something louder use more battery life? | [
"It depends largely on the impedance of the headphones. Most headphones designed for portable listening are going to be less than 25 ohms. Headphones with larger drive coils tend to have higher impedance, and will take more power. ",
"But for things like earbuds, the difference between 3/10 and 8/10 will be negli... | [
"OP didn't mention a phone or headphones, just loud or not so loud. The answer is yes, louder uses more power. If it's a phone driving headphones, it's probably not a large increase. If it's a battery-powered stereo with speakers, there could be a big difference. "
] | [
"Because if there is no load connected to the headphone jack, there is no power consumed, besides processing power. The amplifier will pump out audio signals to the jack, but if there is no coil to receive the signal, the signal just remains as a potential charge across the terminals.",
"Unless of course the phon... |
[
"Was Einstein truly an unmatched genius, or was he just in the right place at the right time?"
] | [
false
] | null | [
"Can't he be both?",
"Einstein was unquestionably a genius. Even in an era of many new discoveries, his own work was both visionary and profound, and extended through many different areas of science; the 'scientific career' section on his ",
"wikipedia page",
" is quite amazing. But at the same time, it was t... | [
"Well, with quantum mechanics (Planck, Bohr, de Broglie, Heisenberg, Schrödinger, Dirac, ",
") I think it's safe to say we've probably got people of equal stature/ability now, and that some of them were just in the right place at the right time, and Einstein was too, to some extent.",
"When it comes to Einstein... | [
"Within a six month stretch in 1905, at the age of 26, while working as a patent clerk, ",
"he wrote four groundbreaking papers",
": ",
"Photoelectric effect",
", ",
"Brownian Motion",
", ",
"Special Relativity",
", and ",
"Energy/Matter Equivalence, E=mc",
" ",
". ",
"He was undoubtedly a g... |
[
"How do medications cause you to gain or lose weight as a side effect?"
] | [
false
] | If you eat exactly the same on and off a medication could it make you gain or lose weight? (Not just water weight, but actual weight in the long term.) I thought weight was just the difference between calories in and calories out, so I don't understand how this happens, but I've definitely gained weight from medication... | [
"Some antidepressants are associated with weight gain due to increased appetite, or similarly changing a person's taste perception. Other drugs might affect how efficiently you burn calories, some might affect how your body actually absorbs nutrients from the food you eat, or how your body makes and stores fat. ",
... | [
"Anti-psychotics frequently have weight-gain associated as a side-effect and olanzapine is no exception. There are a number of plausible mechanisms but if anyone has shown a demonstrable one outside of simple increased appetite then I am unaware of the study. There are treatment options but again, I don't know of a... | [
"What about Zyprexa? It's notorious for making people gain something like 30 pounds in a month."
] |
[
"Does deeper sleep during thunderstorms relate biologically to a decrease in predator activity?"
] | [
false
] | null | [
"Here",
" is the link that got me thinking about this.",
"edit: I meant to link to ",
"this reddit post",
" but copied the wrong link."
] | [
"Dr. Ralph Pascualy is the medical director of Northwest Hospital Sleep Center in Seattle. He explained to me that the brain naturally craves sensory input. That's why people in sensory depravation tanks hallucinate; robbed of any stimulus, the brain creates its own. During sleep in a quiet night, any random noise,... | [
"Continuous pink noise has not ever been shown in any rigorous manner to improve sleep quality."
] |
[
"Do solar flares affect the human brain?"
] | [
false
] | Recently I’ve been reading about solar flares, how they impact the Earths magnetosphere, etc, and I’ve been wondering if they affect the human brain, as our brains are made up of neurons pulsing electricity between themselves. Is there ANY correlation between solar activity and the human brain? | [
"In principle, electromagnetic fields can influence the brain noticeably, if strong enough. This is used in ",
"Transcranial magnetic stimulation",
"(TMS) or ",
"Transcranial direct-current stimulation",
".",
"The biggest solar storm that got measured was in 1859, the so called Carrington Event with 1760n... | [
"I worked with high-field NMR magnets. Even while crawling around below 18 to 20T magnets, I never felt anything."
] | [
"The change in the magnetic field is much more important than the absolute strength, you are right. That's why TMS has a much bigger effect than MRI, as the first uses a pulse, where as the later has an almost constant field but the same field strength."
] |
[
"Is \"crowd wisdom\" effective for anything other than trivial questions?"
] | [
false
] | If, for example, several hundred people are asked to guess how many pennies are in a jar and their answers are averaged out the result will be very close to the actual number of pennies. However, I read an article recently in which a computer scientist analysed global news reports over the last several years and plotte... | [
"As someone in a hard science field, I think it should be noted that the wisdom of crowds is mainly applicable in areas where everyone is equally expert (guessing number of pennies in a jar). If you're asking people what the best grand unified theory of physics is, there's no point to asking a crowd, obviously. I... | [
"Yes I understand this perfectly (I am a physicist!). What I would like to know is if there have been studies which test crowd wisdom in more esoteric areas, such as future predictions, maybe the stock market or race horse betting, that sort of thing. "
] | [
"Yes I understand this perfectly (I am a physicist!). What I would like to know is if there have been studies which test crowd wisdom in more esoteric areas, such as future predictions, maybe the stock market or race horse betting, that sort of thing. "
] |
[
"Would the heat from a hot water tank sanitize most human pathogens?"
] | [
false
] | Our city is under a boiled water advisory right now and I'm wondering if it's better to use the hot water from the tank for basic cleaning (washing dishes etc). I took a temperature reading and our hot water is running at 58 C - 60 C ( . Assuming a hot water tank is set at 70 C is that high enough to kill most human pa... | [
"Microbiologist here. ",
" ",
"If you're going to be eating off of something within ~24 hours of washing it in this water, boil it first. Most organisms will be dead after 24 hours due to lack of nutrition, so if you're waiting that long then it shouldn't be an issue. If you have small children, elderly family,... | [
"Why does it take longer at 138°C?",
"EDIT: It appears that 138°C for 2 seconds is for ultra-pasturization which is a different standard. Also, is this table for milk or water and are they different? "
] | [
"Funny story, I didn't. I was working with ~30 different strains of E.coli of a particularly deadly nature so I was freaking out when the hospital told me that it was E.coli. After the CDC investigation though it the strain I got didn't match any of the ones I had been working with. Turned out that I got it from a ... |
[
"I am in my second year of a four year science degree. I have to pick my speciality soon,i am most interested in biology,what will make me the most employable?"
] | [
false
] | null | [
"askscience is for specific science questions; you should try ",
"/r/askacademia",
" or ",
"/r/biology"
] | [
"Either a medical degree or a Ph.D in some molecular/chemical/engineering specialty. (Definitely don't stop with a BS; the long-term career prospects of bachelor's level biologists are below those of art history majors.)"
] | [
"Is an M.Sc. a bad option ? I just don't want to spend another 4 years at college :(, or an MBA ? Get a job working for a biochemistry company ? Understanding business and science ? "
] |
[
"When does an object reach maximum velocity after an impact?"
] | [
false
] | I'll make the question a bit more specific and I'll try to stick to one single problem, but I will see how it goes because I think different situations could produce different answers. So I got into an argument with a friend about when does a puck reach maximum velocity after a shot. I was confident that it's right at ... | [
"Wow, that's a long question. But I'm going to take a shot (pun intendend) at answering it, because there's a little mind-bending realization about how the world works, in there.",
"Your question is about forces and accelerations. But first, let's just look at forces. One of the first things we learn in physic... | [
"This. ",
"Also, the puck will reach maximum velocity at some time during the push from the stick. As the puck moves away from the stick, the force it feels will start to decrease. At some point the force of the stick will become balanced with air resistance and friction. This means the cceleration will be ... | [
"And also to add to the excellent explanation given by ",
"u/pfisico",
" , this universe has an absolute speed limit. Although it is called the \"speed of light\" because it is the speed at which massless particles like photons (which make up light) travel, a better term for it is the \"speed of causality\". ",... |
[
"What happens to all of the microorganisms which we are constantly inhaling?"
] | [
false
] | There are millions of bacteria, fungal spores, and other microscopic organisms that are in the air we inhale constantly. So what happens to them and us when we inhale them? | [
"Depends on their size. Some are trapped in the nasopharyngeal (nose and mouth) region where they are then swallowed and the stomach acid takes care of them. Then some are deposited in the upper airways where the mucociliary escalator sweeps them out of the lung and again they are swallowed, and the ones that bypas... | [
"Mucus is the major mechanism of trapping microbes that we inhale. It has even been shown that some polymers in mucus aid in preventing bacterial biofilm formation.",
"There is a little review on that ",
"here",
".",
"Other means are cilia in the lungs that aid in sweeping the bacteria away. These are consi... | [
"It's not 100% efficient, especially when viruses and bacteria replicate faster than they are destroyed. There's a lot of biology and chemistry that goes into answering your question properly, so for pollution I'll briefly answer. The composition of the pollution plays a huge role. Metals can dissolve, complex gas ... |
[
"If I take ice II at 500MPa and -80°C, and reduce the pressure to 100kPa, will the ice reorganise itself into ice I? Does it need to be melted in order to transition between its solid phases?"
] | [
false
] | Do any of the solid phases of ice form a stable configuration that can be taken out of its usual temperature-pressure boundaries once formed? | [
"I don't know about ice specifically, but for other materials, phase changes between different solid phases certainly does take place. For example the changes between the different phases in steel is used in order to create the desired microstructure to give the desired bulk physical properties for particular appli... | [
"True, a solid is also not really solid as we think of them mostly. Solid doesn’t mean it doesn’t move. All atoms move constantly as heat is actually the vibration of an atom. The difference is there are forces between atoms and if those forces are stronger then the vibration of the atom they win. For example metal... | [
"The short answer is yes. The reason is what we call \"thermodynamics vs kinetics.\" ",
"Thermodynamics describe the arrangement of matter with the lowest free energy. Given enough time, this is what we expect the matter to do.",
"Whether the matter in your system can actually rearrange itself into that configu... |
[
"Do hearts vary a lot among vertebrates?"
] | [
false
] | I learned recently that mammalian four-chambered hearts are more efficient than reptilian three-chambered hearts. Are mammals special as far as hearts go? | [
"Fav animal fact. Amphibians have a two chambered heart as larvae, then when they hit metamorphosis ,it changes to 3 chambers. All while pumping happily away. did i mention then most species move from being an obligate herbivore to obligate carnivore at the same time and gut track totally rearranges, oh and they su... | [
"Some. ",
"Amphibians and reptiles have 3 chambers with the exception of crodilians which have something closer to a mammalian 4 chamber setup. ",
"Birds the general structure is very similar to mammals, but tends to be larger relative to body size and a bit more efficient to deal with the oxygen demands of fli... | [
"Just commenting to expand on fish hearts; they are four chambered but not the same way as in mammals. As they only have a singular vascular circuit (no lungs), the chambers are all one after another, instead of 2 atriums and 2 ventricles separated by a septum."
] |
[
"Why is the sound quality for AM and FM radio so different?"
] | [
false
] | null | [
"A radio works by decoding a known carrier wave (the frequency you tune in on), AM modifies the amplitude (hight/strength of the waves) and Fm the frequency. As can be seen ",
"here",
"Now the amplitude weakens when the signal travels from far away, producing static. \nThe other method however does not look at ... | [
"The bandwidth would probably be the main reason why they sound so different. This is a technical limitation of AM. You'd think since only the amplitude of the wave is being changed, it would be a very narrow spike on the spectrum. But in reality, it ends up having two sidebands each with the bandwidth of the or... | [
"The bandwidth of AM commercial radio is not a technical limit, it is a political one having to do with dividing up the scarce spectrum at those low frequencies. An AM channel occupies about twice its audio band width in the radio spectrum, plus some margin to separate the stations. It is technically feasible to ... |
[
"When the human body is starving, which minerals and vitamins are depleted first?"
] | [
false
] | And which ones last the longest? | [
"Fat stores are not depleted within days. I'm sorry but that is completely incorrect. A healthy adult man of 70 kg and 20% bodyfat has 14 kg of adipose tissue - or 98 000 kcal. This will last him around 40 days, given a metabolic rate of 2500 kcal/day.",
"You are also mistaken about ketosis and muscle wasting. Mu... | [
"The short answer would be that the water-soluble vitamins would be depleted first. They would be constantly loss due to production of sweat and urine. Fat-soluble vitamins (A, D, E, K) would be depleted next. These would also be the ones that \"last the longest\" so to speak, because it takes a relatively long (da... | [
"The best source I could find about it",
"The reason you won't find detailed studies about this is because they would be entirely unethical to enact. You can't just starve people in unhealthy way to see what happens, the only way you could get these results is to sample a series of sufficiently malnourished peopl... |
[
"Are tropical storms more frequent and powerful now then they were 50 or 100 years ago?"
] | [
false
] | How have the predictions of climate scientists done so far? What were the predictions? What is the most reliable data? | [
"“\nExisting records of past Atlantic tropical storm or hurricane numbers (1878 to present) in fact do show a pronounced upward trend, which is also correlated with rising SSTs (e.g., see blue curve in Fig. 4 or Vecchi and Knutson 2008). However, the density of reporting ship traffic over the Atlantic was relativel... | [
"Note however, from the same source, that: \"A review of existing studies, including the ones cited above, lead us to conclude that: ",
".\"",
"",
"The basic physical of why hurricanes get stronger with warming was developed in the 1980s and is well understood. However, we just don't have enough observations... | [
"Kerry Emanuel at MIT has researched and this question systematically, using historical data. His results show a correlation between ocean temperatures and intensity. This result is obvious given that the thermodynamic efficiency of the systems are proportional to the difference between the surface and stratospher... |
[
"Can light traveling in opposite directions interfere?"
] | [
false
] | null | [
"Yes, absolutely. If you had two plane waves moving in opposite directions then there would be periodic times when the fields were zero everywhere. The wonderful thing about waves, though, is that if you had, say, two wave packets moving in opposite directions, once they were finished \"touching each other\", they ... | [
"Thank you. So if you had, let's say, two beams of monochromatic light aimed at each other such that the the fields canceled along both beams, what would happen to the energy of the light, since it must be conserved. "
] | [
"That's exactly the right question to ask. Good catch. I think I was just ",
" to say what I said. It can't be the case that the fields are everywhere zero for exactly the reason you bring up. The waves will still interfere. But I was wrong to say that it would be totally destructive like that. "
] |
[
"How do fish get into a lake when there's no river/sea connected to it?"
] | [
false
] | And do fish that are in landlocked lakes speciate? Shouldn't each landlocked lake have its own species of fish? EDIT: Thanks for the responses! | [
"One theory is that some species of fish have sticky eggs which can be dispersed when they adhere to an animal's fur, feet, or feathers. The eggs will then drop when they are rubbed off or perhaps the eggs become less sticky as they age.",
"Another theory is that fish eggs may be a bit more robust than we expect... | [
"Alot of lakes that have fish in them that arn't connected to a river or ocean could be planted their by the city/states fish and game. Or it is possible that thousands of years ago it was connected but over time water levels have dropped cause it to be disconnected. "
] | [
"Around these parts (Southern Manitoba) a lot of lakes and even recent human-made lakes (like stone quarries) have been populated by flood conditions.",
"Also for non-fish, ",
"many seeds and invertebrates have been shown survive passage of a birds digestive system",
". "
] |
[
"Why does \"nothing\" sound the way it does?"
] | [
false
] | null | [
"Probably ",
"tinnitus",
". Its pretty crazy how different quiet in your bed at night vs real quiet is. If you ever have the chance to sit in an anechoic chamber you'd be surprised how loud the sound of blood flowing through your body is. "
] | [
"blood flowing through your ears and/or the hairs in your inner ear subtly changing positions. "
] | [
"Are you referring to your ears ",
"ringing",
"?"
] |
[
"What causes magnetism?"
] | [
false
] | What is it about certain objects that causes it to be magnetic? Is it the electron configuration? Is it the overall structure of the atom? Or is it something completely unrelated to its chemical makeup? | [
"It's a combination of the structure/makeup of the atom itself and the crystal structure (how the atoms arrange into a molecule). It comes mostly from the Pauli Exclusion Principle.",
"I'll focus solely on ferromagnetism. There's a few other types that behave differently (paramagnetism and antiferromagnetism), ... | [
"Macroscopic magnetism (like the magnetic field of something you can stick to the fridge) is due to a large number of microscopic magnetic moments that are aligned. Each microscopic magnetic moment is due to the spin of the electrons in an atom or compound. Spin is an intrinsic property of electrons that basically ... | [
"if you look at the (not well known) structure of neutrons stars, they're not 100% neutrons."
] |
[
"Can water freeze under tremendous pressure, like at the bottom of the ocean?"
] | [
false
] | Why isn't the water at the bottom of the ocean frozen? | [
"The pressure at the bottom of the ocean isn't high enough, but yes, water will change to ice if you increase the pressure sufficiently. It's not the same phase as the ice you're familiar with. There are actually many known phases of ice, which occur under different temperature and pressure conditions. Wikipedia ha... | [
"I am an oceanographer, the way water works is the most dense water is super cold, super salty water, this water is on the bottom of the ocean.\n",
"http://www.cgrer.uiowa.edu/people/carmichael/atmos_course/ATMOS_PROJ_98/mapeter/4_atlanticmasses.gif",
"\nIs an example of the water in the Atlantic ocean. The ver... | [
"Examine ",
"this phase diagram",
".",
"At the ",
"Mariana Trench",
", the pressure is 1086 bars, and the temperature is 1 - 4°C. You'll notice in the phase diagram that for ice to begin to form at those temperatures, the pressure needs to be around 600 MPa, while the pressure of 1086 bars translate to 10... |
[
"Many questions about recent /r/science posts about our universe being inside a black hole."
] | [
false
] | My questions come from this article/thread: but I've read others. Questions: 1) Does anyone know how seriously the science community is taking these kinds of theories (the media is never realistic about this). 2) I'm confused about how the influx of matter into a black hole corresponds to the arrow of time for the uni... | [
"That topic was posted in ",
"/r/science",
", which has very different standards from ",
"/r/askscience",
" and can't deliver reliable answers."
] | [
"1) Not very. It's mostly just that one guy working on it. It's a cool story, so they picked up on it.",
"2) The arrow of time markers shouldn't be viewed as something causative: time doesn't advance because of entropy increasing or the universe expanding. Rather, they're ways to figure out which way is which. It... | [
"This is true, although I am thankful that OP has given me a chance to appreciate the source, as I missed it the first time around on my news feed."
] |
[
"Is there a theoretical limit on the wavelength of radio waves?"
] | [
false
] | I apologize if this is a stupid or obvious question, but in textbooks it always says that radio-waves are defined as the electromagnetic radiation with a wavelength between approximately 1m and 1km. Although this does say 'approximately' and may differ by a factor of 10 or so, but is there any theoretical limit on the ... | [
"waves that act like light",
"They don't \"act like\" light, they ",
" light. \"Radio waves\" are merely a subset of electromagnetic waves, no different physically from other wavelengths such as visible light and (on the other end of the spectrum) gamma rays. (I'm sure you know this, but I don't want OP to get ... | [
"waves that act like light",
"They don't \"act like\" light, they ",
" light. \"Radio waves\" are merely a subset of electromagnetic waves, no different physically from other wavelengths such as visible light and (on the other end of the spectrum) gamma rays. (I'm sure you know this, but I don't want OP to get ... | [
"There's no maximum frequency or wavelength for an electromagnetic wave. The idea of splitting up the EM spectrum and calling different ranges of frequencies by different names is a human construct to make things easier. I suppose there's a maximum wavelength where something will be called a \"radio\" wave, but i... |
[
"Animals can survive on \"pet food\" indefinitely. Is there a \"human food\" equivalent?"
] | [
false
] | To reiterate in a more complete way: Is there any food (man made or not) that, like the food we give our pets, could potentially have everything we need for us not to have any diet-related problems? - that is, it would have all the nutrients we need, and close to the amounts that are nowadays deemed as healthy. And if ... | [
"Well, first off, most pet foods claim to be perfectly engineered for the dietary requirements of the animal at hand, but that is a questionable assertion. Grain-based cat food is the biggest offender, which is why now you have diabetes in domestic cats. You take one of the most perfect carnivores that nature ever... | [
"Rob Rheinhart invented Soylent, which is supposed to essentially be a replacement for meals. It is a powder which you mix with water to form a drink. The cost is advertised to be ~$3/meal.",
"I am a bit skeptical as to the health aspects of relying on such a drink for sustainment. There have been claims that the... | [
"That's interesting! Have any studies since corroborated Stefansson's results?"
] |
[
"Why do our attempt to find life on other planets focus primarily on the existence of water?"
] | [
false
] | Why is that all searches for life on foreign planets are focused on the existence (current, past or future) of water? Yeah, life on our planet is dependent on water, but couldn't other forms of yet discovered life be equally dependent on something else, ANYTHING or NOTHING else? Only thing that I can think of is that w... | [
"Because that is the only sort of life we have any concept of.. ",
"looking for something we know nothing about is very hard. ",
"at least with water dependent life we have some sort of frame of reference from which to base our searches. "
] | [
"Because for chemicals to interact they need to be able to move around one another. This rules out solids as they don't move, and this rules out gases as in them particles just shoot around rarely hitting each other. So we know life requires some sort of liquid.",
"Water is the best bet for finding life since i... | [
"Because searching for theoretical forms of life is just a wild goose chase. I'm pretty sure if we discover a form of life that doesn't depend on water, it won't be an intentional discovery; it'll catch us by surprise."
] |
[
"What is the mechanism that allow dolphins and whales to stay underwater for such a long time?"
] | [
false
] | null | [
"They have a high concentration of oxygen binding myoglobin, far more than any humans. Therefore they can store more oxygen for use and as they dive deep down and they cover their blowholes to keep water from getting in to their lungs."
] | [
"Could we, using genetic engineering or some drug simply increase the amount of oxygen binding myoglobin in our blood and be able to hold our breath for minutes under water or is it more complicated than that / would cause deadly side effects. ",
"I know that in cycling they use blood doping and EPO to increase ... | [
"When myoglobin is broken down it is filtered by our kidneys. If you were to suddenly increase that amount I imagine you would overwhelm your kidney and cause kidney failure",
"Edit: also as you take in more oxygen, you’re gonna create more carbon dioxide that your lungs have to get rid of. It would overwhelm you... |
[
"If you were to lie in a pool of white blood cells, would it heal cuts and wounds on the surface of the skin?"
] | [
false
] | null | [
"White blood cells",
" would only disinfect your wounds as they act against foreign materia. If it was instead a pool of stem cells, then that could accelerate your healing a tiny bit, by entering your bloodstream through cuts."
] | [
"I used to know this, but I am really rusty on biology these days. What is it inside your body that heals wounds? As I remember the red blood cells clot the wound to stop bleeding and infection, and then the white blood cells do the healing. I know that the body has very few naturally occurring adult stem cells, bu... | [
"Red blood cells don't really contribute to clotting, it's a feature of other stuff that forms in the blood plasma (fibrin for example)."
] |
[
"How can old films be re-released in higher and higher resolutions a technology of displays progress?"
] | [
false
] | null | [
"Photographic film works by having tiny photosensitive crystals suspended in a gelatin emulsion. When light hits the crystal, it causes a chemical change, and developing chemicals later preserve that change so that you can see it in the negative. The crystals are referred to as \"grains\" and speed of the film (ind... | [
"Film doesn't have a characteristic resolution the same way that digital images do, film has \"grain\" which depends on about a zillion factors. A typical 35mm shot (what a lot of films and tv shows were shot on) will have a grain that corresponds to something between 4 and 20 megapixels of resolution, with the typ... | [
"So film is kinda strange. Theoretically really high quality 35mm should have the same resolution as an 87 MegaPixle image (Depending on who's metrics you use). As with anything, the reality is... well... complicated.",
"Movies are not always shot in ideal conditions, lighting, apertures, Cameras ect. This often ... |
[
"What are the most \"intelligent\" asexually reproducing species?"
] | [
false
] | Among the asexually reproducing species of life on Earth, do any have a brain and nervous system, etc? Of those, which are the most intelligent? (As agreed upon by scientists) (Also allowed are species which have both asexual and sexual reproduction, but I don't know much about these) | [
"Parthenogenesis is a form of asexual reproduction that has been documented in turkey, condors, and quail, so one of them. If you restrict the query to animals who reproduce ~primarily~ asexually though, it's probably stick insects or thrips.",
"I'm just getting this from the Wikipedia article on asexual reprodu... | [
"Asexual reproduction is not incest at all. The problem with incest is that it can expose recessive homozygous combinations (e.g. from heterozygotic parents) that can be deleterious. But asexual reproduction won't do this as the offspring is the same as the parent."
] | [
"It actually does allow for variation, but at a much slower rate. Asexual offspring will still experience transcription errors and other random mutations. Naturally this is less of an issue for organisms that reproduce at a high rate than it would be for complex organisms."
] |
[
"Compared to say, 60 years ago, how harmful are todays cigarettes?"
] | [
false
] | Are they about the same, worse, or better? I'm almost sure the answer is worse but I'm looking for some concrete justification. Would a heavy smoker fare better today or in the 1940's? | [
"Would a heavy smoker fare better today or in the 1940's?",
"Today, for at least two reasons. First, health care is better; there are more treatment options for emphysema, lung cancer, COPD, etc today than there were 70 years ago.",
"Second, filters didn't become widely used until ~1950s, and these did help. Bu... | [
"Well back then it was mostly tobacco. We know for a fact they add many chemicals and fillers now as compared to the 60s. The amount of actual tobacco leaf used is half what it was in the 60s, the rest is fillers of some sort. ",
"[1]",
"Also those \"safer\" Cellulose acetate filters were known to cause dama... | [
"I'd like to point out that there is a persistent myth in our culture that additives in cigarettes make them significantly more dangerous. At the end of the day, you're breathing in a bunch of smoke, and that is incredibly bad for you. An additive can only have a minimal positive or negative effect."
] |
[
"Why do people die of starvation without using up all their bodies' fat reserves first?"
] | [
false
] | I've read that the human body starts breaking down proteins for energy after some time during starvation even when there is still fat left that the body could have utilized to make energy. Why is that so? Also, is it possible for a person to survive on just his fat reserves for a long period of time if he can't find an... | [
"Your body requires more than just fat and protein to survive, and this long list includes your vitamins and minerals that keep your inner machinery working. Not enough vitamin C? Scurvy! No vitamin A in your diet? Keratomalacia!Lacking vitamin B12? Say hello to atrophic gastritis.",
"Again, you can't survive on ... | [
"Don't forget sodium and potassium just to move the muscles with the \"sodioum/potassium pump\". If muscles lack the energy to move then the heart can't pump blood."
] | [
"Your body still needs a base amount of energy to break down the fats. Once it runs out, its out. People usually succumb to dehaydration before they actually starve to death, so to say. Without water, your body cannot do anything. "
] |
[
"How does a neutron star generate a magnetic field if it is composed entirely of neutrons?"
] | [
false
] | null | [
"Mostly because it's not composed ",
" of neutrons - just nearly so. ",
"The very outer layers of a neutron star are \"normal\" matter (as normal as 1,000,000 K matter can be, that is) and probably consist of a very dense fluid of nuclei and electrons. This layer is conductive, and so combined with the very fas... | [
"Of course, all stars are made of subatomic particles, when you get down to it. But what happens in a neutron star is that the protons and electrons - which normally make up atoms - get essentially \"smashed\" together by the extreme gravity. As it turns out, when you combine a proton and electron under the correct... | [
"I am no expert on neutron stars, but I figured I would point out that neutrons, while electrically neutral, ",
" have magnetic moment.",
"The overall charge of the neutron is zero, but it made out of charged particles, their charged just cancel. The distribution of charged particles within the neutron create a... |
[
"Why are UHF TV antennas (almost) always loop antennas, vs. VHF antennas which are usually whip antennas?"
] | [
false
] | null | [
"The length of an antenna is related to the wavelength of the signal it is meant to receive, typically some fraction (1/2 or 1/4). UHF wavelengths are less than a meter, so loop antennas (antennae?) work fine. VHF wavelengths are longer, 1m - 10m, so they need longer antennas.",
"There is math involved, so someon... | [
"It's my understanding that Loop antennas come in two main varieties; self-resonant large-loops where the circumference of the loop is roughly the same size as the wavelength, therefore works better on the high-frequency/short-wavelength bands (so the physical size of the antenna doesn't end up too large) whereas s... | [
"It also has to do with wave propagation and reflection. If you are trying to get UHF frequencies from a single distant tower, a \"beam\" design will still be your best bet. VHF antennas were essentially a beam design. Reflection was a major issue with VHF frequencies. Al loop antenna on UHF is much more forgiving ... |
[
"Is washing your hands with warm water really better than with cold water?"
] | [
false
] | I get that boiling water will kill plenty of germs, but I’m not sold on warm water. What’s the deal? | [
"In a ",
"2005 report in the Journal of Occupational and Environmental Medicine",
", scientists with the Joint Bank Group/Fund Health Services Department pointed out that in studies in which subjects had their hands contaminated, and then were instructed to wash and rinse with soap for 25 seconds using water wi... | [
"Warmer water is better at breaking-down the dirt or grease on your skin, but isn’t shown to have any effect on the bacteria. The quality of the soap and the hand-washing technique are themselves the biggest contributing factors."
] | [
"If removing caustic chemicals, however most substances exhibit greater solubility in water with higher temperatures , thus removing greasy residue better with soap."
] |
[
"is there a limit on how far back in time we can see with a telescope?"
] | [
false
] | I've heard about how the JWST allows us to see things that happened close to the start of the universe. I sort of understand how this works, but I was wondering if there is any sort of theoretical limit on how long ago something could have happened that we could see with the telescope? Are there things that are just ... | [
"There is a limit. As the early universe was opaque, ",
"we can't see past a redshift of ~1100",
"."
] | [
"As further context, JWST won't see anything farther than redshift ~10 because that's when the first galaxies formed. If you want to look farther than that, you need to be searching for the kind of light that was produced or scattered at earlier times, which includes radio waves (from the 21-cm atomic transition of... | [
"There is essentially no light at infrared or shorter wavelengths that was sourced much earlier than 13 billion years ago, because such light is produced inside galaxies. At earlier times, there were no galaxies.",
"The time period between last scattering (at an age of about 350 thousand years) and the formation ... |
[
"Does having exercised in early life have an effect on losing weight later on?"
] | [
false
] | Suppose there are two people at an equal level of fitness, but one has never done sports and the other has had lots of exercise in his youth. Does the person with experience in sports get fit faster? | [
"This is wrong. Your muscles contain no memory at all and that is just marketing/laymans terms of something already completely understood.",
"Muscle memory is attributed to the strengthening of neural pathways in the brain that govern the exercise youre doing. Do it often enough, and you brain has to spend less a... | [
"To answer your question OP, yes the person who has done physical activity in their youth will have a slight advantage, why? Because their brain has to spend less time forming new pathways, essentially increasing their efficiency (gains from the workout) from the start.",
"Someone who has never worked out before ... | [
"Thank you for the correction. "
] |
[
"Can you have a coefficient of friction greater than 1?"
] | [
false
] | My physics teacher said it does exist but I just cannot wrap my head around it. Wouldn't that mean the frictional force is greater than the applied force (assuming its on a flat surface)? So when you push it it would move toward you? I just need some help understanding this. | [
"Yes, it is possible for a coefficient of friction to be greater than 1. One particular example is rubber on rubber, which, according to ",
"this",
", has a static coefficient of friction of 1.16.",
"The idea behind static friction is that in order to get an object moving, the force ",
" that you exert on ... | [
"It can be greater than 1. The thing you misunderstand here is that the coefficient of friction is the ratio of the NORMAL force (or in the simplest case, weight) to the frictional force. For example, say a box sitting on the ground is pushed at a constant speed, and that the coefficient of friction is 1. In this c... | [
"Thanks! My teach failed to mention that it mean less than or equal! It all makes sense now."
] |
[
"Why is consuming cow milk more popular than milk from other animals?"
] | [
false
] | null | [
"Several reasons. ",
"One is that there is a very limited range of animals that produce milk of a texture and flavor that is widely appealing. A lot of animals have thick or strongly flavored milk, but cows milk has a similar fat content to human milk (whole milk is around 4% fat) so it seems \"right\" to us.",
... | [
"In theory probably yes. It wouldn't taste exactly like cows milk, but it would not have the same bitter compounds from all the weird things goats eat. ",
"In practice, good luck stopping goats from eating everything in sight."
] | [
"Does this mean then that, if you had goats that only grazed on grass, you would end up with a milder goats milk compared to how it typically tastes?"
] |
[
"Has the earth's gravity increased in any significant manner since the emergence of life?"
] | [
false
] | I've always assumed that the earth's mass (and by extension gravity) has remained fairly stable through out its history. But I realised maybe I'm wrong, the earth is constantly catching space rocks which could've added mass to the earth, also the earth's rotation is slowing down so surely that'd increase the gravity at... | [
"The short answer is no, there has been no substantial change. The mass of the earth is on the order of 10",
" kg, so for even a 1% change in gravitation potential you would need a change in the mass on the order of 10",
" kg, which is a ",
" amount of matter and far more (in my estimation) than catching spac... | [
"If I remember correctly, in our solar system only the largest gaseous giants actually radiate more energy than they receive from the sun, so that effect wouldn't be a likely mechanism for mass loss on the earth. Even if it were however, tiny amounts of mass convert to huge amounts of energy, so converting the ener... | [
"The Earth loses about 3 kg of atmosphere a second, or about 31,000 tons a year. ",
"http://www.reddit.com/r/AskReddit/comments/150srk/is_any_matter_from_our_atmosphere_gases_for/",
"It gains about 40,000 tons a year from space dust and meteorites. ",
"http://www.bbc.co.uk/news/magazine-16787636",
"In terms... |
[
"Why does most trees have dark bark, but trees like Birch have \"white\" bark? What's the benefit for the Birch tree? Does it effect the tree differently?"
] | [
false
] | null | [
"In Aspens the bark is white because it has chloroplasts embedded in it (sometimes you can see a green or brownish tinge if you look at it up close), and photosynthesis occurs in the bark during winter, helping it survive. In most trees the outer layer of bark is dead tissue called rhytidome which helps protects th... | [
"In birch (not aspens) the bark is flaky and constantly shed. Combined with potent chemical defenses, this makes it very difficult for insects and rot to attack the tree.",
"It is ",
"speculated",
" that the white color and insulation help keep trees from warming up in the winter. Freezing and staying frozen ... | [
"Wow. Is that why birch bark is a good fire starter?"
] |
[
"Does it take more energy for an mp3 player to play music at a loud volume, or is the volume independent of battery life?"
] | [
false
] | null | [
"It does draw more power to have higher volume - there is a relationship between sound intensity and energy. However, things like the LCD screen on the device draw so much more power that the difference should be negligible."
] | [
"Louder draws more power, however when you're talking something just powering earbuds I'd be surprised if it had a measurable difference (Think of the energy require to make the thudding bass in a car, for example. This is why they have multiple amplifiers)"
] | [
"Yes, they will use more power driving the speakers in your headphones if turned up. The output is pretty small though. I think w're talking about anywhere between 1 and 10mw. I think your typical mp3 decoder is going to use around 40-100mw of power and you're also looking at the display driver, storage system (l... |
[
"What's the margin of error for atomic clocks?"
] | [
false
] | null | [
"The ",
"NIST-F1 caesium clock",
" is accurate to 1.5e-15 (1 second in 20 million years). Recently, a German group built a clock based on Ytterbium transitions which ",
"is accurate to 3.2e-18",
", or about 1 second in 10 billion years! "
] | [
"How is the accuracy measured? "
] | [
"That's a question which is very specific to the implementation. Uncertainties from different sources can be added/multiplied/exponentiated/etc in ",
"well-defined mathematical ways",
". The final uncertainty value for an experiment like this (and in fact, most reported uncertainties in science) is a combinatio... |
[
"Earthquakes and Tsunami's speeding up or slowing down time?"
] | [
false
] | I was in my stellar galactic astronomy class today and my professor asked me a puzzling question. He had recently attended a meeting of sorts on the recent disasters in Japan. One of his colleagues had made a comment about how the earthquakes made the day shorter by a microscopic amount and would then in turn make her... | [
"I can say with confidence that the earthquake did not speed up or slow down time.",
"Technically there would be an imperceptibly small time dilation, since it changed the speed of rotation of earth (and thus the people on it)."
] | [
"This question has a few implications. I'll do my best to address them.",
"1) The Earth circles the sun in 365.24 days. If the day were shortened, that would mean that there would suddenly be more days in the year because a revolution still takes a fixed amount of time.\n2) if you live a fixed amount of time, say... | [
"http://www.space.com/11115-japan-earthquake-shortened-earth-days.html",
" it is estimated that 1.6 microseconds were taken from each day, due to the shift in earth’s orbit/mass distrubution. For somebody on the planet this change would go unseen. For satellites and GPS timings this may be more important (not a p... |
[
"Biology: My question is about deep ocean ecology. Are there places in the deep ocean that humans can't submerge into?"
] | [
false
] | I remember watching a documentary where an exploration team was unable to pass through a certain area of the ocean. It looked like an ocean within the ocean. So my question is what are these places and does anyone know what documentary that was? Cheers! | [
"My guess is you saw something like ",
"this",
", where salt water and fresh water meet but don't mix underwater.",
"The reason divers avoid entering the more dense salt water that makes the \"rivers\" is because they have to carefully calculate ",
"their buoyancy",
" to set up their gear (mainly their we... | [
"Wow! Yeah it looked similar to this! The only difference was that it was in the ocean. I'm sure though something similar to this occurs in the ocean. Thanks for answering! "
] | [
"The same sort of thing... \"rivers\" of denser water... does ",
"happen in the ocean",
", but there it's caused by vast temperature differences that haven't equalized yet, as ocean currents mix colder and warmer waters together. So that might have been it."
] |
[
"When you drink cold water, heat from the body is transferred to warm the water to your core temperature. So, how much 32 degrees F water do I have to drink throughout the day to burn, say 500 calories?"
] | [
false
] | null | [
"One calorie raises the temperature of one gram of water by one K. So, each gram of 0°C water would take 37 cal to heat up. 500/37 gives 13,5 g. ",
"Now, keep in mind that what is colloquially called \"calorie\" when it comes to food is actually a kilocalorie. Carbohydrates yield roughly 4 kcal/g. So, to compensa... | [
"I would like to point out that the kilocalorie type of Calorie is always capitalized to differentiate it from actual calories."
] | [
"Thanks for the info - I am not a native english speaker, so that one was new to me. "
] |
[
"When you have mono-zygotic twins, are the chromosomes from one or both parents coded to replicate prior to conception? Basically, is there anything that signals the zygote to split, surely there should be 46 chromosomes for both fetuses?"
] | [
false
] | [deleted] | [
"No. The zygote divides into 2 then 4 cells and so on. Eventually, the cells will start to differentiate, but if the zygote separates into two at this very early stage, each one just goes 'huh', and develops into a new individual. Nothing amazing needs to occur - just that physical split. "
] | [
"Exactly. ",
" cell in your body (barring mistakes) has all 46 chromosomes. A developing embryo is no different. As a zygote begins to become an embryo, it divides many times, replicating its chromosomes for each division. The only difference for identical twins is that the early embryo breaks in two parts, which... | [
"I was thinking more along the lines of DNA. Basically, do people that have mono-zygotic twins on the DNA level does something say (loosely speaking) \"hey we need double everything b/c we are going to split\" or does the splitting just happen, like \"oh shit, replicate\"? What I am trying to get at how do the game... |
[
"I saw massive spider web \"structures\". Does anyone know why they would do this?"
] | [
false
] | [deleted] | [
"Did you actually see any spiders? It's far more likely that this was the work of some species of caterpillar. Here in Maine they are an invasive species and will cover tons of trees and bushes, killing them, as well as being highly allergenic due to their little spines that come off regularly."
] | [
"Although most social spider colonies remain relatively small, they will sometimes form massive webs like this. The answer to the evolutionary \"why\" question is that larger groups are more effective and efficient at capturing large prey than a single individual (see ",
"this article",
"). A web of this size... | [
"On the east coast a number of years back we had a problem with some sort of caterpillar. They left giant white constructions on every tree you could find. Maybe that's what you're thinking of? I think they called it a gypsy moth."
] |
[
"What happens to fat cells as fat is metabolized?"
] | [
false
] | Is fat metabolism basically just a point in time process, or does it kick off a process of longer changes to the fat cells? What is that process and how long does it take? This question comes from a thought I had on a 6 hour bike ride yesterday. | [
"The fat cells (adipocytes) undergo very little changes when fat is used in metabolism, other than decreasing in volume. DNA modifications such as methylation/demethylation and histone remodeling may be long-term effects of fat loss by adipocytes, but this is unclear at this time.",
"A skinny person and a fat per... | [
"So if someone were to have liposuction and reduced the number of fat cells in the body what is the effect on the number of adipocytes long term? Does this have a lasting effect on how fat the person can get from that point on? I'm genuinely curious, not asking for a recommendation on surgery."
] | [
"No, not to any real extent. Adipocytes are basically cell membranes, with a smushed nucleus to one side, and the rest of the cytoplasmic space is filled with fat molecules. ",
"Here",
" is a light microscope pictures of adipocytes stained with hematoxylin and eosin stain, which stains DNA. ",
"Some transcipt... |
[
"How do satellites in space protect their electronics from all the different types of Electromagnetic waves they are exposed to?"
] | [
false
] | [deleted] | [
"They are made inside metal enclosures, so they do have some inherent protection as the body of the satellite itself provides some protection. That being said, they are still vulnerable to em interference. During solar storms they can be disrupted or even destroyed. Another example of a satellite being destroyed by... | [
"One of the biggest sources of damage to satellites is electrostatic discharges. Not direct EM waves. The solar wind, protons and electrons, causes charges to build up on insulation surfaces. The potential builds up until it arcs over surfaces or even out to free space. This causes high surge currents in the satell... | [
"With difficulty. ",
"Usually the electronics are in a sealed metal box. ",
"But then you have to still deal with rejecting unwanted signals on any connections into the box.",
"And, if you are a a responsible space citizen, you do your utmost to prevent to you box of tricks radiating unwanted EMI."
] |
[
"What happens when a newer fossil of unknown species is found in an older rock strata?"
] | [
false
] | Lets say a new cretaceous dinosaur species is living near the bank of a river, The river is continuously eroding the rock on which the cretaceous dinosaur stands on exposing triassic rocks, the cretaceous dinosaur dies near the exposed triassic rocks and gets buried and fossilized. We humans then find this fossil of ne... | [
"In this scenario, the remains of the Cretaceous dinosaur, if it was preserved as a fossil, would be within Cretaceous rocks sitting unconformably on top of Triassic rocks, i.e., the \"gets buried and fossilized\" part implies that the sediment burying the dinosaur is Cretaceous in age. So the fossil would not be \... | [
"Thank you so much for the extremely detailed answer. It answered my question in both practical sense and also in the sense that my curiosity wanted it to be answered in.",
"I would like to let you know that you are sort of a celebrity among my 5 close friends here in India who also study Geology with me for bein... | [
"As Crustal says, you don't really get fossils incorporated into ",
" rocks, because for various reasons you can see the difference between the new rock layer with the fossil and the older rock layer beneath it.",
"What ",
" sometimes happen, though, is a fossil incorporated into a newer rock strata. Imagine... |
[
"If a particle needs to be massless to travel at the speed of light, does that mean that tachyons need to have negative mass?"
] | [
false
] | null | [
"Damn you, Rene Descartes, and your condescending terminology!",
"For real though, ",
"/u/tanzmeister",
", famous French mathematician Decartes essentially had the same this-is-nonsense notion as you for these complex numbers and started snidely calling them \"imaginary\" numbers, and the name stuck. It's a ... | [
"Damn you, Rene Descartes, and your condescending terminology!",
"For real though, ",
"/u/tanzmeister",
", famous French mathematician Decartes essentially had the same this-is-nonsense notion as you for these complex numbers and started snidely calling them \"imaginary\" numbers, and the name stuck. It's a ... | [
"Damn you, Rene Descartes, and your condescending terminology!",
"For real though, ",
"/u/tanzmeister",
", famous French mathematician Decartes essentially had the same this-is-nonsense notion as you for these complex numbers and started snidely calling them \"imaginary\" numbers, and the name stuck. It's a ... |
[
"Can you ferment avocados?"
] | [
false
] | Can you ferment avocados and make an alcoholic beverage from them? Would it taste good enough to drink? | [
"Found ",
"this",
" for ya, hope it helps?"
] | [
"It looks like a ",
"few",
" different ",
"homebrewers",
" have at least attempted to make beer with avocados. They both posted a while ago; you could try and contact them to see if they had any luck. Aside the relatively large amount of oils, an avocado wouldn't be too much different from any other fruit t... | [
"It's the fat and oil that makes it not very feasible as a fermentable fruit. The yeast won't metabolize fat, so it would sit there on top starving anything of oxygen."
] |
[
"Why do you see countershading in some land mammals, when it seems to serve no purpose?"
] | [
false
] | I get why there is countershading in sea animals, the light color blending in with the lighter water above; the dark color with the darker water below. Why though, do so many land mammals have white bellies? Is this perhaps an evolutionary remnant? You see it with all sorts of land animals, but not all either. Horses f... | [
"Countershading can still serve a purpose on land just like in the sea or air. It's not quite as effective, but it still helps to break the outline, which is the most important part of camouflage."
] | [
"I expect it's an energy saving response. The belly of some animals will be white, and therefore unpigmented because, not only is it rarely seen (i.e rodents, mustelids etc.), it is rarely in contact with the sun.",
"How is light-colored belly fur an energy-saving response?",
"If it's an energy-saving response,... | [
"I expect it's an energy saving response. The belly of some animals will be white, and therefore unpigmented because, not only is it rarely seen (i.e rodents, mustelids etc.), it is rarely in contact with the sun.",
"How is light-colored belly fur an energy-saving response?",
"If it's an energy-saving response,... |
[
"What is physically changing in my computer when I overclock my CPU?"
] | [
false
] | I can vaguely picture information being stored in ram, and how different states in a semiconductor move information through logic gates... But when I change the clock speed on my CPU, what is actually happening? I know digital watches have a quartz crystal in them that vibrates at a very specific frequency.... But how ... | [
"There are frequency divider circuits using something called a T flip-flop, which toggles whenever the clock goes high. ",
"More complicated than that. Only the early processors divided the Crystal. Like dividing 4 MHz to 1 Mhz. But in today's world of gigahertz clocks, where there are no GHz crystals, They take... | [
"The crystal always oscillates at the same frequency like you said. There are frequency divider circuits using something called a T flip-flop, which toggles whenever the clock goes high. ",
"If you put one T flip-flop behind another one, you get something that toggles every other clock cycle. Through careful comb... | [
"To add to that, something I didn’t understand about PLLs when I first heard about them is they use a voltage controlled oscillator to increase the clock frequency. So one might use a 10MHz clock to adjust a VCO to 100MHz by dividing the VCO by 10, and comparing the frequencies of the two clocks. Then you go on and... |
[
"Does radio sound have a 'quality'?"
] | [
false
] | We're used to MP3's being in 320kbps or 128kbps. Analagous to that, does broadcasted radio sound have a quality? | [
"Yes.\nFor an analogue wave transmission you have bandwidth and signal-to-noise ratio. Bandwidth in analog signals is similar to sampling frequency of a digital sound. For example, FM channels have allocated bandwidth of 200 KHz, which is plenty to fit a 20 KHz sound wave. That's also why you are able to transmit s... | [
"If it deviates more than +/- 75kHz it is exceeds FCC limits. Analog TV was +/- 25kHz. "
] | [
"I think you mean bitdepth as the analogous digital counter part the SNR. Bitrate is a depends on both the sampling frequency and bitdepth. ",
"Given he knows mp3 files quality by bitrate, I guess it would be good to note how those make up bitrate. Sampling frequency is how many times each second the sound is mea... |
[
"When I breathe casually, why does my stomach move in and out. But when I breathe deeply my chest expands?"
] | [
false
] | [deleted] | [
"When you inhale normally, your diaphragm drops displacing the contents of the abdominal cavity. When you do a forced inhalation, you utilize your external intercostals and other accessory muscles, allowing for further expansion of your chest cavity until your inspiratory reserve capacity. "
] | [
"My fault, continue posting identical answers. I guess we don't capitalize here either, as long as we are telling others what to do. "
] | [
"My fault, continue posting identical answers. I guess we don't capitalize here either, as long as we are telling others what to do. "
] |
[
"Why are there tigers in Primorye and historically throughout Siberia, but none in the similar ecosystem of Alaska?"
] | [
false
] | Was there something that prevented the migration of Siberian tigers across the land bridge between Asia and the New World? | [
"But Beringia may have been reasonably temperate and populated by big mammals. I don't think climate should be considered the main factor. \nSource: ",
"http://www.beringia.com/research/beringia_flora.html"
] | [
"There were a number of large cats that formerly inhabited North America, such as the American Lion: ",
"http://en.wikipedia.org/wiki/American_lion",
" And the Saber-toothed cat: ",
"http://en.wikipedia.org/wiki/Saber-toothed_cat",
"The only species to survive in North America into modern times is the Coug... | [
"Thank you for the response. I was aware of the fact that The Americas were inhabited by large cats in prehistoric times. My question is, \"why did they survive in Asia and not in the New World?\""
] |
[
"Why do dogs like to lick my face and hands?"
] | [
false
] | Is this common to any other animals besides dogs? Is it a socio-behavioral thing? Do they expect something particular in return? These are just a few general question I was curious about. | [
"There are a number of reasons dogs lick. ",
"That is how the mother communicates with her puppies, how she gets them to start breathing and how she cleans them when they are born. You’ll find the puppies (both feral and domestic) will lick around the mother’s mouth...this is just instinct.",
"It’s also sort of... | [
"Ugh. My 1.5 year old dog is a compulsive licker. Terribly difficult to train out of. "
] | [
"Long and preachy, but this is the trainer coming out so bear with me. ",
"It takes discipline on your part, and even then it is indeed very hard to train since it's something that is rooted in their instinctual habits. ",
"For chewers there is this bitter apple spray that you can get at pet stores which makes ... |
[
"I'm new to the idea of emergence..."
] | [
false
] | So I'm new to the topic of emergence and I'm looking for the scientific perspective of it. I recently came across the idea that if a phenomenon is 'emergent' from other phenomena that it supervenes upon - such as laws of social systems emerging from the laws of physics - that it isn't possible to describe the higher p... | [
"I think a better term is \"derivative reality.\" (imo) We know the vast majority of day-to-day physics really well. Does that mean we can solve quantum mechanics ",
" for the interaction between two atoms to make a molecule? No. So we make some assumptions for some simple systems, and maybe we can do those... bu... | [
"but it's not the electrons neutrons and protons that have color. It is the light they emit or reflect that does. And that light, in a way, doesn't care about the arrangement of those various particles. I mean, I understand what you're saying, but I'm trying to encourage the thought that you haven't really created ... | [
"I think it's a concept that becomes quickly misappropriated. I mean, this is why I wanted to encourage you to think along these other lines. If I say that biology is somehow \"emergent\" from physics, that life is something that can't be quantified in terms of particles and forces, then people take this quickly to... |
[
"Is there a way to safely dispose of nuclear weapons?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):"
] | [
"Can I ask how it is fundamentally flawed?"
] | [
"and we can't destroy them. ",
"What makes you think that we can't disassemble them?",
"Why can't we dispose of them outside of earth's orbit?",
"We could, if we wanted to dispose of them, but that would not be cost-effective at all. They can just be disassembled on Earth.",
"Would they be able to survive l... |
[
"Can we think of a Black Hole as just a really really dense planetary body?"
] | [
false
] | I read this and I think it helped explain black holes to me better than I ever understood them, but I want to make sure I have it right. A black Hole is just a body that is so dense that nothing can reach an escape velocity to leave the body. So any body with escape velocity greater than C would be a black hole (assum... | [
"A black Hole is just a body that is so dense that nothing can reach an escape velocity to leave the body. So any body with escape velocity greater than C would be a black hole (assuming that C is the maximum velocity of any object in the current universe). ",
"It's actually quite a bit more complicated than that... | [
"Newp.",
"It's not just the case that you can't escape a black hole once you cross the event horizon: it is impossible to do anything except fall inwards towards the central point. It is literally impossible for any force to hold you up. So all the mass just collapses into a single point."
] | [
"Not really. A ",
"neutron star",
" is a very dense object, so dense that its gravity will bend light when you stand on it, allowing you to see way past the horizon. (And also be crushed to a horrible, horrible death.)",
"A black hole is mostly just empty. As far as we know, all the matter in the black hole i... |
[
"What is a moving node in wave mechanics?"
] | [
false
] | null | [
"A node is just where the oscillatory function goes to zero. Those points can be stationary or moving."
] | [
"Thank you."
] | [
"May I ask if a moving node would in turn do something to a mass in an optical or acustic tweezer setup?"
] |
[
"Is it possible to create a superconductor that works at room temperature?"
] | [
false
] | null | [
"The short answer is that we don't know. We do not understand the mechanism that causes high temperature superconductivity (and we aren't even certain it is the same mechanism in all materials). Since we don't understand high temperature superconductivity theoretically, there is no way for us to predict an upper bo... | [
"Here I go diving into the details, but whether room temperature superconductivity leads to a technical revolution will depend a lot on the kind of progress made in vortex pinning between now and then. High temperature type II superconductors won't be that useful if vortices are continuously dissipating energy. Als... | [
"And if you were to discover a good way to make room-temperature superconductors you'd revolutionise experimental physics, medical imaging, computing, and possibly even fusion power. It would be an enormous technological advance, because a lot of the difficulty with these things comes from the extreme cooling curre... |
[
"How can the transfer of photons between a positively charged particle and a negetively charged particle make them attract each other ?"
] | [
false
] | [deleted] | [
"There is no transfer of photons."
] | [
"Actually, ",
" photons are transferred, which is just a common but misleading way of saying that static/pseudo-statc electromagnetic fields emanate from charges and exert forces. A real photon is an asymptotically free oscillation in the electromagnetic field. All other forms of the electromagnetic field; static... | [
"Yes, the electromagnetic force is carried by the quantized electromagnetic field as described by QED field theory. In a particle physics context, we refer to the QED field as a collection of photons, but that does not mean that we always have real photons."
] |
[
"What is the origin of the quadratic formula?"
] | [
false
] | I used to know this back when I did honours maths in the Irish version of high school, but I can't remember anymore, it is my favourite formula in applied maths so I thought I might ask the hyper intelligent mathematicians of r science to impart the knowledge. | [
"Do you mean historically or a proof?",
"Historically, the Babylonians had some concept of the problem (~2000BC) and the ancient Greeks (~300BC) were able to generalize and find solutions geometrically (when they made sense). Between 0-1000 AD, many Indian mathematicians worked with it, and eventually lead to a p... | [
"I was indeed referring to the proof, however the history is interesting and appreciated. Alot of forgotten terms that i need to relearn there with your proof's, even though you already have simplified it down. But thank you for feeding my curiosity. "
] | [
"It's derived by factoring through completing the square, there was a slicker method but I forgot it now.",
"This is worked through step by step: ",
"http://m.wikihow.com/Derive-the-Quadratic-Formula"
] |
[
"A question about cooling atoms..."
] | [
false
] | I didn't really want to start a new thread with this question, however the right comment to ask hasn't come up. Following the link about "atomtronics" it mentioned about cooling atoms using lasers. I have seen and heard about this quite a few times however still not sure about how this works. I believe they managed t... | [
"It's a process that takes advantage of both relativity and quantum mechanics.",
"Atoms can only absorb photons of specific energies; that's the quantum-mechanical part. If you shine light at a material, photons that can be absorbed will be, putting the atoms that absorb them into an excited state. An atom in an ... | [
"There are several methods of laser cooling, the most widely used is called Doppler cooling, which uses the Doppler shift to its advantage.",
"An atom can only absorb discrete energies. Two lasers are pointed at each other, with the atom in the middle. The energy of the lasers are set so that if the atom moves to... | [
"It's actually pretty neato. You need to know the energy levels of the element you want to cool. Then you tune your laser to ",
" a little ",
" the frequency that would excite an atom in its ground state to some higher state. Then you shoot that laser on there from all six directions. The thing is now that only... |
[
"Does pilot wave theory work with experimental results of (delayed choice) quantum erasers?"
] | [
false
] | [deleted] | [
"s types, those who just can't get around the philosophical matter of wtf QM is saying, and people outside of QM. I think the vast majority of physicists are still (professionally) \"Shut up and calculate\" types; the question of an ontol",
"Very interesting. Would you be able to also explain how, in the model of... | [
"There is no science in this. The different interpretations make no difference to any predictions of the theory."
] | [
"Yes, it does (by getting rid of locality and adding a deterministic, FTL, universally present \"Pilot Wave\"); the the reason that theory isn't quite dead is that it still manages to make the same predictions as QM. The reason that nobody cares who isn't a devotee is that it's not much of a theory... just another ... |
[
"Why do I get a static shock from everything this time of year?"
] | [
false
] | Every time I touch something metal, something touching metal (I just got a shock from touching my damn taquitos in the oven) or people, I get a shock. Why does this happen and is there anything I can do about this? | [
"Get an ionizer. I run a commercial 3M ionizer. You can measure static energy in the air with a multimeter.. Point the ionizer at it, and you can watch the voltage drop. "
] | [
"I've been thinking of it as the worst super power ever. My archnemesis is the door knob on my back door. Earlier, that thing shocked me so hard that I heard it. "
] | [
"I've been thinking of it as the worst super power ever. My archnemesis is the door knob on my back door. Earlier, that thing shocked me so hard that I heard it. "
] |
[
"If an atom's electrons zip around at high speeds, what do they look like when two atoms form a covalent bond?"
] | [
false
] | Hi, I've been teaching myself chemistry in my spare time recently, and in general I understand bonds and that electrostatic charges cause them to form. But they're tricky to visualize. Diagrams and models are of course static, whereas in reality electrons are jumping all over the place. So, say I've got NH3. Normally, ... | [
"...the electrons interfere with each other in such a way that they resolve to a lower energy state upon bonding. If they are behaving as standing waves, then they must be undergoing destructive interference to acquire this lower energy state.",
"This is wrong. Let's first approach this using molecular orbital t... | [
"When you form a bond, the behavior of the electrons don't really change per say. They are still very much moving around just like on a single atom. But what changes is where it is doing the zipping. In a molecular orbital, the electrons are either zipping around multiple atoms or primarily hanging around in be... | [
"Isn't the model of \"electrons zipping around\" a classical interpretation of what is really more of a probabilistic quantum distribution? "
] |
[
"Is it possible to harness the Earth's magnetic field for flight with a strong enough and self stabilizing electromagnet?"
] | [
false
] | [deleted] | [
"For flight...very unlikely. The Earth's magnetic field is something like 30 to 60 microteslas at the surface of the Earth (depending on your latitude), which is minuscule. For reference, the superconducting electromagnets used to control the proton beam at the LHC are on the order of 10 Teslas...so about a milli... | [
"There's no need to point out someone's lack of understanding, if they understood the concept in the first place they wouldn't need to ask about it."
] | [
"q has to be 0.5232 gigacoulombs. That is...immense. I mean, that is so unbelievably big it's ridiculous. There are probably BIG ramifications to this.",
"The biggest rammification would be that, in the case of positive charge, which is easier to get by in larger quantities than negative charge (electrons will ju... |
[
"Is there a reason, from like... a linguistics standpoint, that people say \"like\" so much?"
] | [
false
] | Maybe this is a dumb question, but I was thinking about this earlier when I caught myself saying "like" numerous times in a conversation. I've always kind of noticed that a lot of people, including myself, do this. Then I thought why on Earth would that be a thing? Why the word "like"? Do other languages besides Englis... | [
"Generally \"like\" is used as a linguistic filler, which indicates the person is thinking about what to say next. Previously, people seemed to use \"um\" and \"ah\", but we seem to have moved away from that to using terms such as \"like\" or \"actually\".",
"As a poor French speaker, I tend to need fillers all t... | [
"In Mandarin they say 那个 all the time. (Sounds like \"negga\", btw.)",
"Without any solid evidence I would hazard a guess that it's almost 100% cultural. No-one I know outside of a certain social sphere uses \"like\" in the way you're describing. I'm strongly of the opinion it's a learned cultural behavioir. "
] | [
"I'm not sure 'like' means exactly the same thing as 'um' or 'ah'. 'like' in its \"filler\" usage has a softening effect, because it has the effect of making the speaker seem less articulate, more casual, it can be used to make criticism less harsh. Compare",
"You're like such a hypochondriac",
"You're um such ... |
[
"How strong of a magnetic field is required to rip iron particles from the bloodstream?"
] | [
false
] | This occurred to me after reading AMA about a man who had magnets implanted in his fingers and his concern about taking a MRI. Not sure if its even possible, but what a old 4T MRI machine can do. | [
"That depends entirely on the hemoglobin state. Deoxyhemoglobin is usually paramagnetic. ",
"To answer the OP's question though (and this has been asked before): You cannot do this with a magnetic field strength that's anywhere near what we can create. You'd be talking about something like hundreds of thousands o... | [
"Hemoglobin (iron containing protein in blood) is slightly ",
"diamagnetic",
", and would be repulsed, not attracted to a magnetic field."
] | [
"You can read ",
"all the previous questions here",
". The short answer is that the iron in your blood is not ferromagnetic, thus won't be attracted like the metal objects you see in the video."
] |
[
"What's between protons/neutrons and electrons?"
] | [
false
] | null | [
"There isn’t anything “between” them. Their wavefunctions all overlap somewhat in space."
] | [
"Electrons in s orbitals have a nonzero probability of being in the nucleus."
] | [
"Electrons in s orbitals have a nonzero probability of being in the nucleus."
] |
[
"How exactly do we get used to capsaicin?"
] | [
false
] | A few years ago, my idea of spicy was something along the lines of cayenne pepper sauce. As I'm typing this, I'm enjoying a cheese sandwich spiced up with a Madame Jeanette chutney. What happened to my body to allow me to sit through this sandwich with enjoyment rather than burning screams of agony? | [
"Another tangential question: if you hold water in your mouth when your tongue is burning from spice, the burn is completely gone. But as soon as you swallow the water the burn comes back. What's going on here?"
] | [
"Chilli (capsaicin) is detected by the capsaicin-receptor (TRPV1) on the surfaces of heat-sensing pain fibres. ",
"Science doesn't completely understand the process of habituation (tolerance) to capsaicin exposure - but it is thought to be because of down regulation of the receptor (i.e. reduction in the numbers ... | [
"afaik it is oil-soluble, so the milk helps because it contains a lot of fats"
] |
[
"Why is hot chocolate powder still dry when it comes out on the spoon?"
] | [
false
] | A cup of hot chocolate and a spoon with HC on it , dip it in and its dry about 70% of the time. | [
"When you stick the loaded spoon in the cup of milk/water, the surface layer is dampened, then keeps more moisture from migrating to the center of the spoonful of powder because the powder particles on the surface have become stuck together, and the gaps between the particles is too small to let water through.",
... | [
"Is there a way to minimize it? It's frustrating."
] | [
"Well, with hot chocolate...adding the powder to hot milk or water by pouring it in (slowly...not all at once), then stirring, works best for me. You will still have some clumps, but the heat will melt/help dissolve the clumps. And keep stirring, as the agitation action of stirring also helps break up the clumps."
... |
[
"Does Teleporation violate the 3rd law of thermodynamics?"
] | [
false
] | I am FAIL and meant the because I forgot they start at zero. If teleportation over practical distances (football field or a mile) with larger masses (like a human or a truck) is possible, then does one of these have to be true? I hear about small "quantum sized" objects being teleported small distances in sensational n... | [
"Who claimed you could do that without expending energy?"
] | [
"Quantum teleportation is ",
" actual teleportation, and it's very frustrating that newspeople won't make the distinction. Quantum teleportation involves transporting the state of one system onto another; it's an interesting phenomenon in and of itself, but it's not the same thing as transporting matter.",
"But... | [
"Why would it violate ",
" law of thermodynamics?"
] |
[
"If the speed of sound in fresh water is nearly 1500 m/s, why do the ripples on a pond travel so slowly?"
] | [
false
] | Are they fundamentally different types of wave? | [
"Yeah they are different types of wave. Sound waves are ",
"compression waves",
", whereas ripples are ",
"displacement waves",
", (more specifically ",
"gravity-capillary waves",
").\nSound relies effectively on the mechanical properties of water (I am in no way an expert on that), whereas ripples rely... | [
"this is also why when there is an earthquake, the p-waves (or compression waves) are detected first, and the s-waves are detected second. It's just a difference in the way the energy is propagated. "
] | [
"If you're interested here's another type of wave, soliton, that travels at less than 1 feet/s:",
"http://www.youtube.com/watch?v=PyjwZ39EDmw"
] |
[
"The owners of WannaCry attack can withdraw the bitcoin money without being tracked by police? How?"
] | [
false
] | null | [
"There is no way to match a Bitcoin address to a person. It's not like an IP address that is assigned based on your location. However, there is a public record of every Bitcoin transaction, and if the attackers tried to directly sell the bitcoins for real money, then the exchange they use has information about who ... | [
"But someone ends up with the stolen bitcoins, and the authorities could chase them. Don't people who use mixers worry they could end up with \"hot\" bitcoins in this way?"
] | [
"The coins could potentially be confiscated without charging the owner with a crime. This is what happens to people who unwittingly buy stolen goods from someone, if the police track the goods to them. A lot would depend though on where the mixer resides, and if the country they are in has any laws in place regul... |
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