title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"The Moon and Sun influence our oceans tides and waves, but do the moon and sun also influence the clouds movement?"
] | [
false
] | I have seen a few timelapses of clouds given the fact that the moon has an effect on our bodies of water on the surface of the earth, can the gravity also have a real/noticeable effect on the clouds and their movements? Are pressure gradients seen in weather systems a result of this, or mostly just temperature? Additio... | [
"The waves you are seeing in those videos are not as a result of tidal phenomena. They are most likely gravity waves or Lee waves (although I am not an atmospheric expert so it could be some other kind of wave).",
" ",
"The Suns influence on the atmosphere is primarily of a thermal nature rather than gravitatio... | [
"The waves you are seeing in those videos are not as a result of tidal phenomena. They are most likely gravity waves or Lee waves (although I am not an atmospheric expert so it could be some other kind of wave).",
"I did suspect this was the case. However it is what prompted me to wonder whether clouds are affect... | [
"I don’t see why not, if the moon phases are strong enough to impact the oceans, certainly they would be strong enough to impact water vapor. It seems like basic physics that liquid water and water vapor would move similarly in waves. ",
"Interesting concept. I’d like to start looking at weather patterns relative... |
[
"What happens if 2 black holes collide ?"
] | [
false
] | null | [
"They orbit around each other for a bit, then merge and create a larger black hole! In the process of orbiting, they emit ",
"Gravitational Waves",
" - just like accelerating charges emit electromagnetic waves, accelerating masses emit gravitational waves. These waves radiate out some energy, so the resulting b... | [
"\"these wave radiate out some energy\" SOME ENERGY. In the last millisecond before the colision the event radiated out more energy than all the stars in the entire observable universe combined ",
"blackholes ~3,6*10E49 Watts",
"universe ~10E22 Stars so ~ 3,8E48 Watts"
] | [
"They form a larger black hole. The gravitational waves emitted in the process have been observed many times now.",
"https://en.wikipedia.org/wiki/List_of_gravitational_wave_observations"
] |
[
"How is it possible to smell metal?"
] | [
false
] | For example, copper has a specific smell. Perhaps it has to deal with oxidation? Maybe the two oxidation states of copper form some sort of complex or oxide with the atmosphere and we're able to smell the aerosol of that certain compound? Edit: words | [
"You smell the volatile compounds that are formed from the catalytic degradation of compounds from the skin by the metals.",
"see ",
"http://www.reddit.com/r/askscience/comments/2av2i8/ask_anything_wednesday_biology_chemistry/cizu8z9",
" for a paper on this"
] | [
"I still cant seem to find an answer though! Also, every answer seems to be different.",
"I posted this in another thread:",
"This really intrigues me because iron and copper do differ in smell! Its weird because most of the noble metals like platinum, gold, and silver dont smell, while copper and iron do. I wo... | [
"I still cant seem to find an answer though! Also, every answer seems to be different.",
"In each thread you'll find the same answer - the metal catalyzes the degradation of oils on your skin, and that is what you smell.",
"I'm not sure what answer you are actually looking for, if you're not happy with the answ... |
[
"What can you do with a 128qbit quantum computer? ('cause apparently they sell them now)."
] | [
false
] | Saw . As a (so-so) programmer, I'm intrigued. How would one go about using one? I hear quantum computers make current encryption methods obsolete. Can quantum decryption be serialized, or do you need a minimum number of qbits for it? If the latter, how strong an encryption can this break? And my understanding of quantu... | [
"When I get a bit more time, I'll try to come back and answer your questions in detail, but first things first: Dwave is NOT selling a functional 128 qubit quantum computer. It's a scam."
] | [
"Ok, so DWave's 128 qubit thing is not a quantum computer. Most notably, their collection of noisy qubits does not generate entanglement, which is a prerequisute for almost all quantum computing algorithms. A good source of information is Scott Aaronson's blog. See, for example, ",
"his latest post",
" on DWave... | [
"Far too good to be true. The article atimholt linked to isn't bad."
] |
[
"Currently in Canada, funding has been announced to create Mo-99 using an electron accelerator to produce medical isotopes. How is this done?"
] | [
false
] | Background: | [
"If they do use an electron accelerator, the way that would work would be bremsstrahlung. The electrons will hit some high z target like tungsten and release a lot of high energy photons. These then help by causing two reactions. One is (gamma, n) on Mo100 which will produce Mo99. The secondary reaction is the ... | [
"An area I am familiar with, I did my Masters on accelerator production of Mo-99 a few years ago. I didn't see where it said it would be an electron accelerator used, just a particle one. Typically cyclotrons would be used and the particles would either be protons or deuterons. You can get a variety of reactions... | [
"I found this:",
"Diagram of the proposed process. An electron beam from a linear accelerator is used to produce high-energy X-rays. X-rays shine on a target consisting of molybdenum-100 (Mo-100) discs. An X-ray strikes the nucleus of a Mo-100 atom, knocking away a neutron to create molybdenum-99 (Mo-99), which d... |
[
"Does the Universe have something like a frame rate, or does everything propagates through space at infinite quality with no gaps?"
] | [
false
] | null | [
"There is nothing in any of our current state-of-the art theories (quantum field theory, or string theory) which implies that the universe has a \"frame rate\" or a smallest meaningful length.",
"Another commenter mentioned the Planck length and the Planck time in this context; currently there is no reason to thi... | [
"These might interest you:",
"http://en.wikipedia.org/wiki/Planck_length",
"http://en.wikipedia.org/wiki/Planck_time",
"As a rough summary, the Planck length is the theoretical shortest possible measurable unit of length. The Planck time is the time it takes for a photon traveling at the speed of light to tra... | [
"So I get that the Planck length doesn't constitute a \"minimum\" length, but it does seem like the universe stops keeping track of information as carefully at very small distances -- locations become probability fields, such that (to my layman's understanding) only a finite amount of information is encoded in the ... |
[
"Started lifting weights regularly this January. I haven't had a hangover since January. Are these related?"
] | [
false
] | null | [
"there's more water in muscle cells than there are in fat cells. if you have gained significant muscle mass, its possible it would take more alcohol to get you to the same level of drunkenness. not sure about exercise-hangover relationship"
] | [
"Thanks, In the other thread it's sounding like it must just be increased water and protein intake. Still ain't complaining though."
] | [
"Don't forget the liver! Increased liver activity from working out can significantly increase your liver enzyme levels; your liver is responsible for detoxifying your blood after a night out so an increase in liver activity/enzymes would mean it would be more efficient at metabolizing all that toxin out of your blo... |
[
"What field science researches the fungibility of elementary particles?"
] | [
false
] | null | [
"Ok, that actually makes sense. The difference between distinguishable and indistinguishable particles determines which energy distribution (the probability of finding a given particle with a given energy) they obey, so if they are distinguishable they will obey Maxwell-Boltzmann statistics, whereas if they are in... | [
"Chapter 7 of Schroeder's book on thermodynamics, "
] | [
"The fungibility of them?"
] |
[
"How does your stomach keep from digesting itself?"
] | [
false
] | null | [
"To put it simply, it secretes a mucus that coats the walls of the stomach. This mucus provides a barrier and also contains bicarbonate, which helps neutralise the stomach acid coming into contact with it. Too much acid or under secretion of mucus can lead to irritation and inflammation to the stomach and can cause... | [
"The outermost cells of the stomach lining are also recycled about once every seven days, as with other mucosal membranes."
] | [
"Inflammatory prostaglandins also play a role in protecting the mucosa of the stomach and small intestine. If you take enough anti-inflammatory drugs, especially on an empty stomach, you just might start digesting yourself. This is how ibuprofen causes gastrointestinal problems."
] |
[
"How are rocks determined to be from other planets?"
] | [
false
] | How is it determined that a meteorite isn't just a rock originating from the earth? How do they determine it came from a specific planet (i.e. Mars)? Further, if some alien technology was discovered could you use the same principles to determine that the materials used in the technology didn't originate from Earth? | [
"Meteorite researcher here. First to clarify, I'm going to talk only of existing planetary bodies. Most meteorites were formed upon parent bodies that no longer exist. This leaves us only the terrestrial planets, Moon, and a couple of large asteroids (focusing specifically on 4 Vesta).",
"The simplest way is to e... | [
"You're correct that isotopes are used to distinguish meteorites, and for a first check \"is this from Earth or not?\" isotopes that are uncommon on Earth's surface are a good gauge. However, the most common way to distinguish meteorites (both from Earth rocks and among themselves) is their oxygen isotope ratios. "... | [
"You're correct that isotopes are used to distinguish meteorites, and for a first check \"is this from Earth or not?\" isotopes that are uncommon on Earth's surface are a good gauge. However, the most common way to distinguish meteorites (both from Earth rocks and among themselves) is their oxygen isotope ratios. "... |
[
"How does my camera know when its focused?"
] | [
false
] | I assume they use some kind of algorithm to identify certain patterns, but how does it differentiate between blurs and image details, and how does it know its "done" focusing? | [
"This is probably drastically different between camera manufacturers. My guess is they're looking for sharp lines. In image processing this is basically done with integrals.",
"To put it simply though: They scan through the image looking for very fast changes in color/brightness. A very fast change represents a l... | [
"The simplest focus algorithm is to maximize contrast in the image. Because contrast is so easy to measure (just compute the variance of pixel value over a small region) you can do it in a really cheap (nowadays) system, or do it simultaneously in many places on the image plane in a more expensive system. ",
"V... | [
"This is exactly how calibration tools work for manual lens ALPR cameras. You have a computer connected to the camera and viewing the \"live\" picture. You aim the camera at a license plate target and manually focus it to get it pretty close, then in the calibration app you select a region of the image. A histog... |
[
"Does the presence of heavy elements in the Earth indicate we are made from a remnants of a former supernova? Was it part of the Milky Way? Do we know anything about its nature, stellar environment, or even when it occurred?"
] | [
false
] | null | [
"The heavy elements in the solar system were not formed from a single supernova, but from ",
" supernovae mixed together. Supernovae disperse over a period of thousands of years, and mix into the general mess of interstellar gas. So what happens is that over time, the supernovae going off all over the galaxy will... | [
"That is the mainstream interpretation. The particular ratio of the all the elements among various objects in the solar system is taken to form a particular \"fingerprint\" of the specific molecular cloud from which our system coalesced. Our star ",
"is believed to have formed alongside others",
" in the sam... | [
"That is exactly why you don't find primordial Neptunium on Earth. The same supernovae that produced all of Earth's Uranium and Thorium would have produced Neptunium as well, but all traces of the latter has long since decayed away and the only Neptunium you find in nature are trace amounts in Uranium ore as a resu... |
[
"Where does the energy go if you have a Power Generator / Solar Panel / Wind Turbine that is not wired up to anything?"
] | [
false
] | I always wondered this. So there are some giant generators across the world, that are pumping out huge amounts of current. Where does that energy go if you just cut the wire? | [
"Friction and nowhere.",
"What happens in a spinning generator is that the total absence of current would reduce the \"counter torque\"* to zero. The generator would speed up until the regulator reduced the torque applied to the generator to maintain desired speed. This would reduce the amount of power going to... | [
"You are correct about solar cells. Electron holes pairs would still be produced and attempt to travel creating a voltage, but without anywhere to go would simply recombine and create heat. It would heat up like a black panel in the sun. ",
"Photovoltaic cells have current-voltage curves that look like ",
"this... | [
"No. You have an open circuit if it's not generating electricity. There may be initially some movement of electrons with some energy consumption, but soon the charges will accumulate on one side and they won't move anymore. When the turbine stops moving they will flow back to balance charges and give back the bit o... |
[
"If I will build RLC circuit with oscillating frequency of visible light (400-789 THz), would it glow?"
] | [
false
] | ....but if not - why? | [
" you could built a circuit that oscillates at visible light frequencies then it would glow.",
"However at those frequencies the impedance of the circuit would be so high that it wouldn't function."
] | [
"The frequency response of any second order system has really bad high frequency attenuation.",
"Additionally, solid state devices cannot even be driven at optical frequencies (~500 THz).",
"But yes, if you created an antenna that oscillated at optical frequencies, light would spew out."
] | [
"Why is impedance so high at such high frequencies?"
] |
[
"When can we say two things are \"touching\"?"
] | [
false
] | I realize that when we get down to the nitty-gritty, two particles cannot touch because that's not a well-defined concept for particles; they don't have absolute positions, space is a continuum so points cannot be side-by-side, and on an atomic scale there are electric and nuclear forces stopping what we might consider... | [
"Engineers will consider two objects as \"touching\" when they are directly exerting force on each other (by a means other than electromagnetism or gravitational attraction), or when they are close enough to do so. ",
"In practice this means they are close enough to have molecule-to-molecule or atom-to-atom force... | [
"Whenever you want. The concept of \"touch\" is not an essential one. It's a convention, basically. So the definition is going to be one of widespread agreement, not mathematical rigor."
] | [
"No. As I said, it's not an essential concept. Any time \"touch\" figures in, you're really interested in tension or momentum exchange or tensile strength or something along those lines, at which point whether something is \"touching\" or whether it's just bound in some way is beside the point."
] |
[
"The Big Bang and the Big Crunch?"
] | [
false
] | null | [
"This post is too broadly worded, and contains too many questions to be appropriate for ",
"/r/askscience",
". Please turn it into a question that addresses a specific scientific issue."
] | [
"Well my point was. How much info do we have currently that both exist. The Bang is widely known but how about the crunch?",
"I just want to know what is the most widely accepted theory about the end of the Universe these days and does it cycle?"
] | [
"I just want to know what is the most widely accepted theory about the end of the Universe these days and does it cycle?",
"OK. Post that."
] |
[
"What affects the size of hydrogen bubbles formed during the hydrolysis of water?"
] | [
false
] | [deleted] | [
"This might be a little too speculative to be helpful, but I'd have to imagine it would have to do with the viscosity and/or surface tension of the liquid/solution. Possibly altering the ionic/salt concentration would also have an effect. I'd guess that less viscous solutions with lower surface tension and higher i... | [
"I would also think voltage makes difference too. Also temperature. Hydrogen gas has so called over charge that is voltage that has to be added in order to provide energy for bubble to unstick from metal. This is highly dependant on type of metal electrode is made of and temperature"
] | [
"Electrochemist here (ignore the flair, I switched fields). ",
"The size of bubbles formed in a water splitting reaction will be governed by a few factors, but the most pertinent would probably be current density (itself a function of reaction overpotential, electrode surface area, and the specific electrocatalys... |
[
"Am I expanding with space?"
] | [
false
] | [deleted] | [
"You aren't actually stretching the rod.",
"But you are though, ever so slightly."
] | [
"The pressure driving the metric expansion of spaces is believed to occur uniformly throughout the universe. However it is dominated by gravity within galactic superclusters and definitely insignificant when it comes to electromagnetic and nuclear forces at the scale of a human body.",
"So no the space between t... | [
"No. The expansion of space doesn't exert any significant force on matter, so even extremely small degrees of any binding force will counter the expansion of space. Even galaxies in relatively close clusters, such as our own local cluster, are gravitationally bound to each other, which is why the Andromeda galaxy i... |
[
"How do you calculate when two differing sinusoidal signals become in phase?"
] | [
false
] | Given two signals f1 = sin(w1 t + b) where w1,w2 are radial frequencies and a,b are some initial phase, there will be moments when f1 and f2 are perfectly in phase (i.e., add constructively) and moments when they are perfectly out of phase (i.e., they exactly cancel). How does one calculate the time points when these c... | [
"The arguments of the sine functions should be equal when the two are in phase"
] | [
"To solve for the point where the signal is maximized, you find the time point where each of the arguments of both the sine functions are equal to pi/2 + 2 * pi * n, while for the minimum, you have to find the time point where the arguments of both the sine functions are equal to -pi/2 + 2 * pi * n.",
"Needless t... | [
"Thanks, that makes sense."
] |
[
"Why is a cancer therapy like BNCT not viable for every type of malignancy?"
] | [
false
] | [deleted] | [
"BNCT is Boron Neutron Capture Therapy. It works on the principle that boron can be delivered to a tumor. Boron interacts preferentially with neutrons. Send a beam through the tissue and it mostly deposits energy where boron is present. The problem is that you have to get the boron exactly where you want it.",
"F... | [
"Thank you!"
] | [
"I'd never heard of this treatment before, but it was an interesting read. One possible consideration is that a tumor in someone's brain is less accessible than say a gastric tumor. So surgery may be more practical for localized tumors outside the brain, but BNCT is more practical in the case of brain tumors."
] |
[
"Since retroviruses integrate their DNA into their host's, and they replicate by regular cell division, could a virus then increase the rate of cell division and thus cause a tumor?"
] | [
false
] | Are there viruses (probably non-human) that already do that? | [
"Yes. HPV might do that (although it’s a DNA virus), causing cervical, vaginal, penile, throat and anal cancers. It’s also extremely widespread in our species, (and mostly asymptomatic) so it’s pretty hard to avoid.That’s why everyone is encouraged to get the shot.",
"There are other ones, but that’s the one I th... | [
"Yes, it certainly happens in animals, and there are some human viruses that also are associated with cancers. Historically, there was a period in the 1970s/80s where it was thought that most human cancers might be caused by viruses, which led to a lot of research that was valuable, but that showed that viruses are... | [
"Sure, but hepatocellular carcinoma is only about ",
"5% of human cancers",
"."
] |
[
"Is there any form restrictions on the scale factor a(t) in FLRW cosmology?"
] | [
false
] | I understand the hubble parameter is defined in terms of a-dot/a which can be further represented as the density parameters omega, however, is there a restriction on what a(t) can look like mathematically? In de Sitter space, a(t) ~ exp(Ht) for instance. Also if there is no such restriction, that also applies to the Fr... | [
"I'm not entirely sure if I understand your question, but this is the scale factor ploted against cosmological time, based on observational data. The only thing I can say about the form, in general, is that one would expect it to be quite smooth. But that too is based on what I know about the universe, so I don't k... | [
"Sure, observation is king, but the vacuum solutions of GR allow for all sorts of possible universes even if we ourselves do not inhabit such a universe. So my question is more so, mathematically, what kind of scale factors are allowed for toy universes.",
"Essentially, can I plug in whatever I want without break... | [
"I should probably modify my original edit, there might be some special or contrived a(t) that would break the assumptions of the FLRW metric. I'm really not an expert on the subject."
] |
[
"Do/did oligocellular organisms exist?"
] | [
false
] | I would suppose the transition to multicellularity was at least somewhat gradual, but I've never heard of di- or tri-cellular organisms. Do or did these oligocellular (not sure if word) organisms exist? If not, how did life make the seemingly massive jump from single celled organisms directly to multicellular organisms... | [
"Eudorina",
", a colonial green algae, has 32, 64 or 128 cells per colony."
] | [
"Awesome, this is exactly what I was looking for."
] | [
"But do the two cells in a Diplococcus bacterium have distinct functions? I was wondering if there exists an organism with <100 cells, but with differentiated cell types."
] |
[
"Could the laws of physics change from galaxy to galaxy?? Or is there any possible way that the laws of physics could change??"
] | [
false
] | null | [
"Put it like this: It's ",
" but there is no evidence to suggest that they ",
". There's no a priori reason that ",
" or ",
" couldn't have a spatial dependence, or a time dependence, but (so far) applying the same physics from here on Earth to the sky has had phenomenal success, and compelling evidence wou... | [
"I don't think the 'laws of physics' would change really. They would have to be rewritten. That's really what you're talking about here. You mean to suggest that an object would behave one way in a galaxy given certain properties, and different way in another. This might be true, but then we would also try to figur... | [
"The laws of physics could not change between galaxies within our universe. The set of laws that govern our galaxy are the same set of laws that allow galaxies to form in the first place.",
"The first sentence is incorrect, and the second sentence is just a guess. There is plenty of room for the possibility that ... |
[
"how does adding impurities lower the melting point and increase the boiling point of a substance?"
] | [
false
] | I've always read that but how do we define an impurity? Can it be anything that is not wanted in the substance? So if I just put some specks of dust into water, it would freeze at below zero? But if I were to have a pile of dust and put in some droplets of water, will the dust pile now melt at a temperature below its m... | [
"Colligative properties occur mainly due to entropy. A solution made from two substances will have a higher entropy - more microstates, or \"arrangements of molecules\" - than both substances by themselves. In the case of water and a solute, freezing or boiling the water leads to separation of the two substances (v... | [
"Well first let us define boiling point the boiling point is the point at which the vapor pressure equals the surrounding pressure. ",
"The raising of the boiling point is something called a colligative property. Which means that it is a property affected not by what the solute (impurity in this case) is but th... | [
"It's not affected by what it is but the quantity of it? Does it mean that if we put a impurity that is non volatile, then the boiling point increases and melting point decreases? I heard that the impurity have to be soluble solvent, but when there is the melting point depression the impurity can't dissolve in the ... |
[
"How are we so confident that blue whales are the largest animals ever to have evolved on Earth? Could there have been larger sea animals whose skeletons remain inaccessible to human science because of depth or distance?"
] | [
false
] | null | [
"We have to go with the evidence that we have.",
"It's wrong to say \"We are 100% certain that blue whales are the largest animals that have ever existed\", since we can't be 100% sure of that. But based on what we know, it definitely seems that way. Is it possible that there have been bigger animals? Sure.",
"... | [
"You're significantly over-estimating the quality of the fossil record.",
"Also, don't forget that the vast majority of our oceanic fossil record has been recycled back down into the mantle.",
"You're right that we have no evidence for anything bigger as yet, but the fossil record is almost laughably incomplete... | [
"Mainly because it's awkward and time consuming to go around saying things like \"Blue whales are the largest animal, assuming some larger animal hasn't existed, died off, and left no trace.\" We ",
" confident that blue whales are the largest animal to have ever lived on earth in the sense that you are saying.... |
[
"Why two electrons with same spin cannot co-exist but protons can?"
] | [
false
] | I dont have proper knowledge about particle physics and Quantum mechanics but from what i know I would like to ask that if 2 electrons of same spin cannot exist in the same orbital (pauli exclusion) then how can several protons exist in the nucleus together (and neutrons too)? Please do provide some links from where I ... | [
"They also cannot. Nucleons in a nucleon are placed in \"nuclear orbitals\", and being fermions two identical ones cannot be in the same \"orbital\" with the same spin.",
"However, the forces binding the nucleus together are much larger than the EM force between nucleus and electrons, which means these nuclear \"... | [
"https://en.wikipedia.org/wiki/Nuclear_shell_model"
] | [
"Thanks fella"
] |
[
"Can two consecutive frames from a camera be exactly the same?"
] | [
false
] | If I'm running a video camera on an extremely still scene (eg. in my living room where there is no wind) and I grab two consecutive frames, is there a possibility of both frames being totally identical? By identical, I mean each pixel is the exact same color, and they both have the exact same checksum when saved to a f... | [
"Technically yes, but you have to cheat. All pictures produce some sort of grain. ",
"It looks a lot like old style grain on antenna TV.",
"Basically since ISO 0 doesn't exist you will never get two photos exactly the same.",
"However! If you were to take a photo of the sun at a 30 second exposure time you ... | [
"You always have shot noise, which is still what would be considered \"grain\" even with single photon sensing."
] | [
"There's only so many code values and only so many pixels... There's a finite - large, but finite - number of images of a certain resolution and bit depth."
] |
[
"When bees make honey, do \"other\" substances get in the honey?"
] | [
false
] | If bees exclusively use pollen from tobacco plants, does nicotine get in the honey, or if the bees pollinate only marijuana plants, would THC be in the honey? | [
"The source of the nectar does have an effect on the honey. I'm not sure if THC or nicotine would be in it, but the composition of the honey changes. For instance, clover honey is light in color and more mildly flavored than the darker and creamy avocado honey."
] | [
"There is a flavor, and appearance difference, so SOMETHING has changed. I wonder if there are medical properties, like what they prescribe for medical marijuana that the honey could help sick people."
] | [
"Honey has long been purported to have medicinal value for a wide range of conditions and symptoms. While I can not speak to the validity of such claims, it is highly unlikely that cannabis honey even exists, let alone contains enough cannabinoids to affect anyone eating it.",
"Cannabis does not produce a nectar ... |
[
"[Human Body] Is blood a liquid when it's inside the body or does it change to a liquid only once it leaves the body? Is there a way to see inside the body and observe blood in the body?"
] | [
false
] | null | [
"Yes, blood is liquid inside your body."
] | [
"Please give me a way to prove this. It's so obvious, I know. But can you prove it!?"
] | [
"https://en.m.wikipedia.org/wiki/Blood",
"It's up to them to provide evidence to the contrary"
] |
[
"When black holes collide, is there an explosion and why?"
] | [
false
] | Nothing can escape a black hole, yet when things collide they release energy. What happens when black holes collide? | [
"They form a larger black hole. Nothing escapes the event horizon. There is no light, or what might be called an explosion. Other materials around the black holes may emit light.",
"However during the collision, and while the event horizon is not symmetric gravitational waves are emitted from above the event ... | [
"An astronaut doing a spacewalk near the black hole merger would not feel anything. A very large spaceship with size comparable to the gravitational wave wavelength (100s of kms) would experience time varying tidal forces as different parts of the ship are moved in different directions by the gravitational waves as... | [
"What effect would these gravity waves have to an observer close by? Anything noticeable?"
] |
[
"What percentage of our body mass is DNA?"
] | [
false
] | What percentage of our overall body mass does DNA account for? | [
"DNA is about 500 atomic mass units per base pair. We have about three billion base pairs per cell and about 100 trillion cells. That means we have about 10",
" base pairs of DNA or about 250 grams."
] | [
"I'm more concerned with the order of magnitude than the exact amount."
] | [
"The length is a more impressive stat. It would stretch to a percent of a lightyear, or 300 times the distance from the Earth to the sun."
] |
[
"Would a sealed glass box with a candle in it start to fill with water/condensation if the air outside the box was cold/freezing?"
] | [
false
] | If yes, how much water would be stuck to the glass? If not, why? | [
"I would think the limiting factor would be the amount of oxygen in the box. The flame would go out before condensation or frost (on the outside) could form."
] | [
"Yes, If the walls were below the dew point of the specific humidity of the box. The amount of water would be related to the partial pressure of the water vapor for the temperature, ie there would be enough vapor to satisfy thermo equilibrium for the system at that temp and the rest would be liquid. If you are hot ... | [
"The condensation/dewpoint process remains the same it is just a matter if the partial pressures that are driving it can be reached. it would be a pretty easy calculation to see if it would happen if some variables were fixed."
] |
[
"Would the gravitational waves of a massive object moving at the speed of light theoretically stack?"
] | [
false
] | [deleted] | [
"SKRules is correct, but if gravitational radiation for some reason traveled at less than the speed of light and something were to travel faster than that then you would get \"gravitational Cerenkov radiation,\" the emission of which would slow things down. Because we see protons travelling so close to the speed of... | [
"You would have to find some way to substantially slow down gravitational waves. Consider it like a material with an index of refraction that slows down the bulk travel of light. If you have a particle that happens to be moving faster than the slowed-down light, you get Cherenkov radiation: it's why nuclear reactor... | [
"Massive objects cannot move at the speed of light. Your question is not well-founded."
] |
[
"Question for someone that understands the FDA drug approval process."
] | [
false
] | I apologize if this question is too specific, but I am having trouble finding answers anywhere else. Mifamurtide is a drug used against osteosarcoma in youth and children. The drug was denied approval by the FDA in 2007. As I understand it, they found some problems with the data. I've read through the actual and there ... | [
"As a result of that FDA report, mifamurtide was denied approval by the FDA",
"As previously announced, in the U.S., the Company continues to work with the COG as well as external experts and advisors to gather patient follow up data from the Phase 3 clinical trial of mifamurtide and to respond to other questions... | [
"I don't think the USA is a small market by any means, and it is a big blow to any company that doesn't manage to get FDA approval. It's not so much as the cost for the new trial, because they're not starting from scratch again, it's simply whether or not they expect different results. It's a waste conducting a stu... | [
"Also, while this isn't a universal rule, it's pretty commonly observed by people who work with the FDA that the approval process in Europe is a good deal quicker than the process here. (There are a ",
" of drugs/devices/procedures that are approved for use in Europe/Asia, but are not approved here). "
] |
[
"Can a fetus be allergic to something the mom isn't? What happens if she ingests something the baby is allergic to?"
] | [
false
] | [deleted] | [
"Short answer: No.",
"Long answer: A fetus (or infant) can't have allergy. Allergy is mediated by the acquired immune response. Kids don't have an acquired immune response until ~6 months of age (I'm talking 6 months after they are born). They can't have allergy for the same reason they can't hold their pee...the... | [
"Just once? I haven't seen data on that.\nBut breast feeding in general? Yes, asthma. And that's it. ",
"http://researchnews.osu.edu/archive/sibbreast.htm",
"Note that this article says that while breast feeding is great for a number of reasons, not all women are capable of breast feeding their children-- a... | [
"Just once? I haven't seen data on that.\nBut breast feeding in general? Yes, asthma. And that's it. ",
"http://researchnews.osu.edu/archive/sibbreast.htm",
"Note that this article says that while breast feeding is great for a number of reasons, not all women are capable of breast feeding their children-- a... |
[
"Does mediation have any scientifically proven benefits?"
] | [
false
] | Meditation seems very popular these days, and people attribute it a lot of benefits. I would like to know if this practice has ever been evaluated in a scientific way? | [
"There is Wikipedia article ",
"Research on meditation",
" that should get you started. It would be nice if people having new references and information would edit that page.",
"ps. In my opinion, asking that kind of question is like asking: \"sports seems very popular these days, and people attribute it a lo... | [
"Yes there are quite a few studies done on meditation that show it does indeed have positive results. Most of the studies have been done on TM meditation, the most prominent form of meditation. I don't have any links, but google TM meditation science or something along those lines and you should get some results to... | [
"http://www.sciencedaily.com/releases/2005/11/051110215950.htm",
"Meditate! It's good for you!"
] |
[
"Why does the US and Canada have no native primates?"
] | [
false
] | There are all kinds of primates in a vast array of climates on the Eurasian land mass, but in this part of the world we are lacking. | [
"The answer to this question is quite complicated. New World monkeys did not arrive in South America until around 35-43 million years ago. At that time, South America had separated from Africa, but the Atlantic ocean was quite narrow. There is a ton of controversy about how they got there, but the ocean levels were... | [
"I don't have an answer for you, but it is worth noting that ",
"there is fossil evidence of primates in the United States,",
" and that not all of North America is devoid of simian life: there are plenty of monkeys in Mexico."
] | [
"It is worth noting that generally speaking, modern primates do not inhabit much of the northern hemisphere (Japanese Macaques are a notable exception), it is generally accepted that early primates were adapted to an arboreal environment, more suited to SA, Africa, and South Asia, and less suited for NA, Europe, an... |
[
"How exactly does a mouthful of water stop a sneeze?"
] | [
false
] | I have suffered from fairly severe allergies all of my life, which always result in sneezing fits that can last from a few minutes to over an hour. But many years ago, I accidentally discovered that holding water in my mouth for at least a minute will completely stop the sneezing. Ever since, I've passed along that tip... | [
"Having heard this before and tried it myself, I have two things to say.",
"It's not universal.",
"Trying it as a spur-of-the-moment experiment during a departmental meeting in front of all your colleagues and your boss is ",
" not a good idea."
] | [
"I did ",
"mention it",
" on Reddit before, so I hope you didn't spray your colleagues with water because of me. I would almost feel bad if it wasn't so humorous to picture."
] | [
"You'd probably have to go find a physiologist (usually they're lurking in biology departments and medical schools), but if I had to make an educated guess, I think what's happening is a variation on something called the vagus response. Without going into crazy amounts of detail, the vagus nerve runs from the brain... |
[
"Would it be possible to maintain a constant stream of urine if one kept intaking fluids at a consecutive rate?"
] | [
false
] | null | [
"If we assumed an average urine flow rate of 20mL/s, halved it (as you'd want to be urinating slowly) to 10mL/s, and assumed a 100% conversion of liquid intake into urine (obviously a vast overestimate) then you'd have to consume 36L of water in an hour to maintain a constant flow. ",
"This is obviously impossibl... | [
"Depends what you mean by a constant stream. If you mean at the normal volume you’d urinate at, then no, your kidneys couldn’t produce urine that fast. But if you keep drinking fluid, or have a constant IV, then your kidneys will constantly be producing some urine. If you had a catheter in, you could drain that uri... | [
"Thank you! That is what I was wondering. "
] |
[
"Is there any scientific basis to the idea that creatures such as Dolphins and Whales have their own form of consciousness or sentience?"
] | [
false
] | null | [
"What do you mean by 'intelligence' and 'sentience'? Depending on how you define those, the answer is either 'yes', 'maybe', or 'no'. ",
"Under any scientific use of the word intelligence, yes, dolphins and whales are most certainly intelligent, along with countless other species. This is very well documented and... | [
"I think it's important to clarify that when you say the \"same level\" as humans, you mean the same level as the average adult human. There is a wide range to human intelligence and sentience, and there is undeniably overlap with other animals."
] | [
"When compared to the variance in intelligence between species I belive that the variance in intelligence among humans would prove negligible. The difference between the intelligence of Einstein and Forrest Gump would be virtually zero when compared to the difference between any human and a chimp. ",
"Saying the... |
[
"What happens to my muscles when they tire? As in, why can I lift something really heavy, but only for a short period of time?"
] | [
false
] | What makes it so the muscle can no longer hold the weight? edit: Lots of great and helpful answers! Thanks a bunch. Now I feel like I need to lift things instead of sitting on my lazy ass. | [
"A byproduct of this is actually lactic acid, which builds up in your muscles and makes them sore the next day.",
"Just one small correction: It's pretty well understood now that lactic acid is not responsible for delayed onset muscle soreness.",
"http://www.scientificamerican.com/article/why-does-lactic-acid-b... | [
"A byproduct of this is actually lactic acid, which builds up in your muscles and makes them sore the next day.",
"Just one small correction: It's pretty well understood now that lactic acid is not responsible for delayed onset muscle soreness.",
"http://www.scientificamerican.com/article/why-does-lactic-acid-b... | [
"Just wanted to add a bit of information about how exactly muscle works physiologically.",
"But anyway, because it's a cycle, it requires ATP to go full circle and continue contracting. I know that's a little odd and I'm not explaining it 100% accurately, but it's good enough for our purposes.",
"Just to provid... |
[
"humans metabolize vitamin D on exposure to sunlight. Do completely fur covered animals do the same? if not, how do they metabolize vitamin D?"
] | [
false
] | null | [
"From wiki:",
":",
"In some animals, the presence of fur or feathers blocks the UV rays from reaching the skin. In birds and fur-bearing mammals, vitamin D is generated from the oily secretions of the skin deposited onto the fur and obtained orally during grooming"
] | [
"Straight Dope",
" debunks this. Someone tracked down the original paper referenced by the textbook referenced by wikipedia, and apparently the paper was pretty doubtful about putting forward this explanation. There is also the evolutionary observation that we evolved fairly recently from a long lineage of furry ... | [
"Thanks for the verification/truth. Even cited sources are not always to be trusted."
] |
[
"How is it that voltage lags current in a capacitive AC circuit?"
] | [
false
] | I thought that voltage is the force that “compelled” current to flow, so how could it be that current can flow “ahead” of voltage? | [
"Instantaneously, what is happening is that current is proportional to the derivative of voltage: i=C dv/dt. There's no anticipation: if voltage sits steady for a while and then starts to change, there will be no current until it starts to change.",
"With a steady sine wave, it turns out that dv/dt is largest wh... | [
"Voltage is indeed still what causes current to flow",
" But its not like capacitors can see the future so that kind of thinking isn't actually very solid. The whole leading the voltage thing thing is only really true for periodic sinusoidal esk signals anyhow. ",
"A better, and in a sense the correct, intuitio... | [
"How could current flow without an electric potential energy? "
] |
[
"Relativity question in regards to motion"
] | [
false
] | As I understand it, we are moving through time at a certain speed, and as we speed up in regards to space, we move through time slower. But then, when we slow back down, we are traveling just as fast through time as we were before we sped up in regards to space. However, how do we regain the speed we lost in regards to... | [
"A better explanation than most can give: ",
"http://www.reddit.com/r/askscience/comments/fjwkh/why_exactly_can_nothing_go_faster_than_the_speed/c1gh4x7",
"Focus especially on the part about halfway down, starting with the line, \"Imagine you're driving in your car when something terrible happens: the brakes fa... | [
"Definitely said better than I could. The important thing to note is that slowing down in space and speeding up in time are not seperate actions that you happen to take at the same time; they're just two parts of the same action, which look special to us only because time looks special to us."
] | [
"A word of caution: When thinking about relativity, one really must cling with the focus and purpose of a toddler seeking its mother to the fact that ",
"For example, you say here, \"we are moving through time at a certain speed.\" A certain speed relative to what? It turns out there's no definite answer to that.... |
[
"What is the point / significance of determining whether or not our universe is a simulation?"
] | [
false
] | I've seen a lot of articles lately on Reddit talking about determining whether or not our universe is a simulation. an example from the front page. I don't understand the significance of this theory, though. For someone to have come up with it, there must have been some type of physical meaning behind it, something th... | [
"That's a different kind of quantization. The kind these stories you've been seeing are talking about is just a simple grid with cubic cells, or something like that - it implies that spacetime is not a continuous entity, but rather a discrete set of finitely spaced points.",
"The kind of quantization we expect (n... | [
"It's philosophy. If everything was a simulation then it could just as well be simulated in a way that when tested for always reported that it wasn't a simulation. There's no way to definitely prove it one way or the other and as such is within the realm of fiction."
] | [
"This would be a great question for ",
"r/askphilosophy",
"."
] |
[
"I would love to see the physics equation for this post."
] | [
false
] | I'd like to know how much % bigger each domino has to be in order to be successfully knocked down. If any of you are interested as well and have the physics background, could you show how you come to the answer? | [
"Take a look at this: ",
"http://www.math.udel.edu/~rossi/Math512/2005/Team3.pdf"
] | [
"I'm not going to go through and derive it, but here is the outline of what you need to do:",
"The relevant input variables are the dimensions of the dominoes (you need all three dimensions as well as the ratio of sizes between the smaller domino and the bigger domino) and the spacing between them. Density and t... | [
"I did a bunch of work, and got something that looks like an answer. I made some assumptions (outlined below) and found the minimum height-to-height ratio ",
" you need (as in, how much taller each domino is than the previous) for a given height-to-width ratio ",
" (is our domino a square or more rectangular?):... |
[
"When using gravity assist to go to interstellar space, does the mass of the spacecraft have any significant effect on the speed gained?"
] | [
false
] | Also, side question but kinda related. Is there an upper speed-limit on how fast an object can go when using gravity assist? As I understand it, the limiting factor for going the speed of light is the amount of fuel you'd have to carry. But if you're getting your propulsion from gravity assists, then would that no long... | [
"While technically true, the loss is completely negligible. Consider Voyager stealing some of Jupiter's energy during a flyby versus an Imperial Star Destroyer doing the same maneuver- while one is much bigger than the other, both are smaller than Jupiter by an absurdly huge factor."
] | [
"The speed of the spacecraft after the assist can be given by:",
"v = u_1∙(m_1 - m_2)/(m_1 + m_2) + 2∙u_2∙m_2/(m_1 + m_2) (",
"pretty version",
")",
"Where u_1 is the initial speed of the craft, u_2 is the initial speed of the planet, and m_1 & m_2 are the masses of the craft and planet respectively. As you... | [
"If your goal is to leave ",
" then a gravity assist doesn't help you. If you want to leave the Solar System it does help you, as the planet is moving in the Solar System. If you are at rest relative to the Sun (not really a realistic situation, but considered here for its simplicity) then Jupiter is approaching ... |
[
"Why does low blood pressure make you shaky?"
] | [
false
] | Everything I can find is just listing shakiness as a symptom of low blood pressure, but what is actually happening at a cellular level that causes your muscles to not work as well? | [
"There is a lot going on at the cell level. Cells are not getting enough of what they need. Blood is not moving fast enough and the body is being starved. Adrenal glands begin producing more chemicals to try and facilitate the lack of oxygen and nutrients carried by the blood to keep you standing. The kidneys and l... | [
"Not eating for a long time can cause low blood sugar which would have similar symptoms and effects. ",
"Your body is good at storing nutrients and releasing it but it operates most efficiently on a consistent schedule. Once you break away from the norm the body has a harder time regulating itself and delivering ... | [
"Does the same phenomenon occur when someone does not eat for a number of hours?"
] |
[
"Is it possible to have instantaneous change in velocity, acceleration, or ANY of the higher derivatives of position?"
] | [
false
] | As I understand it, it's impossible to have instantaneous change in position because it would require infinite velocity. Likewise, it's impossible to have instantaneous change in velocity, since it would require infinite acceleration. So, I'm assuming that it just keeps going on like this as you keep getting into the h... | [
"Mathematician here. You're asking whether or not the function which maps your position as a function of time is infinitely differentiable. This is a question which transcends empirical testability."
] | [
"These higher derivatives can be quite large, but they can't be infinite. Consider releasing a ball from your hand in a vacuum. In order of the acceleration to immediately jump from 0 m/s",
" to 9.8 m/s",
" you would have to let go of the ball instantaneously. You can't do that though. There will be some (s... | [
"Is nature infinitely differentiable? In some cases the answer is definitely \"No.\" Phase transitions, for instance, can be defined as discontinuities in one of the derivatives of the free energy.",
"In other cases it depends on your model. For the ideal classical model of dropping a ball from rest at time t ... |
[
"Is the oxygen level in Denver (1 mile high) the same as the oxygen 1 mile directly above a random beach?"
] | [
false
] | I'm curious if there's a reason that one spot might have a higher oxygen level then another and why? Does that same hold true for the peak of one of Colorados mountains at 3 miles high vs 3 miles above a beach? | [
"What do you mean when you say oxygen level? Contrary to popular thought, oxygen is at 21% up to roughly 70,000 feet. Air density and pressure are lower higher up, however. Just wanted clarification on the question."
] | [
"The answer is roughly, yes. The exact value of the pressure at a given height will change with the movement of high- and low-pressure systems, and the latitude and average temperature does matter a little bit, but typically this will not change more than 1-2% from average.",
"If you're interested, the average pr... | [
"I'm sorry you're right, i guess I should have asked about air pressure instead of oxygen level. Is the air pressure the same in denver as it is 1 mile above the beach?"
] |
[
"Why do rockets fly upwards instead of sideways like a plane lifting off ?"
] | [
false
] | null | [
"Almost all of the work an orbital launch rocket does is flying sideways. That's the hardest part of getting to orbit, getting up to orbital speed.",
"But consider the problems of doing this at low altitude. Atmospheric drag. The problem of crashing into the Earth from losing altitude. Low rocket stage performanc... | [
"Planes go sideways partly because they have to in order to generate lift. Also their destination is always somewhere else on the ground. Rockets sometimes go sideways, if their destination is on or near the ground. But for those going to space, up is the shortest path there. Once above the majority of the atmosp... | [
"There are some curious responses here. It sounds like you're just after a simple answer:",
"The key difference is that a plane generates lift using its wings and flies in the atmosphere to do that.",
"A rocket is typically built to leave the atmosphere and the two biggest obstacles to doing that are atmospheri... |
[
"Would passengers of a spacecraft that wasn't in orbit still experience the same amount of weightlessness?"
] | [
false
] | So, as I understand it, spacecraft such as the ISS and other orbiting objects experience weightlessness (microgravity, whatever) because they are technically just in a state of constant free-fall as the the Earth curves beneath them. So then what would happen to a theoretical spacecraft that was designed to travel beyo... | [
"Arguments about the definition of \"noticeable\" aside, I think the fact that astronauts already experience that level tidal force right here on the ISS makes it perfectly reasonable for me to have pointed out that astronauts on this hypothetical deep space voyage, possibly on a much larger spacecraft, and possibl... | [
"As long as their engines were off they would be weightless just like they are in orbit around earth. Depending on how how close they passed to the \"orbiting bodies\" you refer to, and how massive those bodies were, they might experience significant ",
"tidal force",
" within the spacecraft."
] | [
" Unless you are passing near a black hole's event horizon, no single person would feel a difference in pull between their feet and head. "
] |
[
"If a supersonic aircraft gets hot from compression heating, does that mean that the air behind it is colder because it transferred heat to the aircraft?"
] | [
false
] | Additionally, if you had a perfect theoretical model (ignoring the inconvenient physics) could you fly a second aircraft behind the first that would get colder? | [
"Not exactly, remember that airplanes aren't coasting, they are generating power from their engines, that heat ultimately is dissipated into the atmosphere. Also, consider a similar scenario: re-entering spacecraft. The spacecraft doesn't have engines producing heat as it re-enters but it is converting gravitationa... | [
"I like the way you are asking. ",
"The answer is both yes and no. The turbulent air behind the craft does cause a sort of ",
"convection effect",
". What is happening with the heating of the plane though is that both the plane and the air are heating each other. The energy of the molecules get friction force... | [
"Think about where the energy is coming from. The air is heated by compression because the plane is pushing it forwards faster than it can move out of the way. The plane gets its energy from the fuel. The air behind the plane will be warmer than it was before the plane passed through, and that energy comes from bur... |
[
"If a Space Elevator was constructed, how could it be decommissioned and deconstructed?"
] | [
false
] | I feel I have read a fair amount on how they might construct a space elevator (materials, etc...), and disasters involving a space elevator (detachment from earth or satellite), but I can't remember reading about how you would safely remove a Space Elevator from service if it was decommissioned or damaged. How would yo... | [
"Unhook it from the ground and it will float off into space. A space elevator would require a massive \"anchor\" that is outside earth's geostationary orbit (the center of mass of the whole system needs to be above geostationary orbit). The same force that keeps the line taught for normal use will pull it away from... | [
"The base would be under constant tension being pulled upwards. As soon as you cut it, off it goes, straight up. Hold a string in both hands and pull. Release one side. Does the string sit and dally around your fingers at all?",
"Also, a space elevator would be a thin tether, not very damaging, and any elevator w... | [
"How realistic is space elevator anyway? Even with all the progress in carbon nanotubes we are no closer to being able to build one."
] |
[
"How do bugs become fossils by being trapped in amber? Cant other small animals can be fossils the same way?"
] | [
false
] | null | [
"Yes, anything can be preserved in amber. Aside from small critters like arachnids and insects, we’ve also found pieces of larger animals like the tail of a feathered dinosaur. Bugs are most common because they can be fully encased and tend to crawl around on trees a lot.",
"http://news.nationalgeographic.com/201... | [
"According to this",
" it’s not just insects. Plants, lizards, and dinosaur feathers have also been trapped.",
"Being trapped in amber is basically what it sounds like. You get caught in amber. The trick is that amber isn’t a solid substance when it starts life. Amber is a liquid, a very thick liquid, at first.... | [
"anything can be preserved in amber",
"I'd like to think that someone will soon discover a specimen and there will be a team of scientists studying the just-a-smidge-too-dark foundation, pastel purple lip-gloss, false eyelashes, and hoop earrings of a high-school Amber from the late '90s that got trapped and pres... |
[
"What are constants like Planck's constant? Is there a reason for these seemingly arbitrary numbers to be necessary components of an equation?"
] | [
false
] | [deleted] | [
"Physical constants in SI units tend to be \"messy\" in that they have many digits or very large/small orders of magnitude because they are expressed in \"human-sized\" units, e.g. the meter, second, kilogram, etc.",
"For effects that are very strong or weak compared to human scales, this causes the relevant phys... | [
"That's why they are long, messy numbers. ",
"There is a relationship between the energy of a particle and its wavelength. Because energy and distance are different characteristics there is necessarily going to be some conversion factor.",
"Why is there a relationship between wavelength and energy? It's a p... | [
"Mathematical constants like Pi and e arise from nature. For example, the ratio of a circle's circumference to its diameter happens to be an irrational number (a number that cannot be represented by a finite fraction, and therefore cannot be represented by a finite or repeating decimal). We find this number usefu... |
[
"What evidence (if any) exists to demonstrate catching Covid creates the same level of antibodies as any of the first doses of the vaccines (does catching it give a higher antibody count than the first dose of the vaccine)?"
] | [
false
] | null | [
"The phase 1 trials studying the immunogenicity of the vaccines often would use convalescent serum (which is serum taken from people who recovered from Covid-19) to compare the magnitude and the level of neutralizing antibodies generated by the vaccines.",
"Here is one publication for example, I'm not sure if its... | [
"What's important to conaider here is the variant that the convalescent plasma donor was exposed to. While titers are inportant, its also important to consider which epitopes the antibodies bind to, and does this binding prevent viral success (completely deactivate the virus). I have seen very different statistics ... | [
"For additional context, BNT162b1 and BNT162b2 were vaccine candidates under development by Pfizer. Trials on BNT162b1 were discontinued because of BNT162b2's comparable efficacy with fewer systemic reactions. BNT162b2 is the vaccine candidate from Pfizer with an EUA from the FDA.",
"https://www.nejm.org/doi/ful... |
[
"How can isobutane have a global warming potential of only 3.3 times that of CO2 when methane is roughly 80-90 times that of CO2 (within the first 20 years of emission)?"
] | [
false
] | I read Wikipedia articles on alternative refrigerants, which are of interest due to HFC refrigerants commonly in use having extremely high global warming potential, often thousands of times higher than CO2 and extremely long atmospheric lifetimes. One alternative refrigerant that has gotten a lot of attention is "Green... | [
"A major part of assessing the global warming potential of a molecule is determining where in the IR region the IR absorption bands exist. CO2, CH4 and O3 are all significant greenhouse gases because they absorb IR radiation within a region where water doesn't. In this sense, any increase in their atmospheric conce... | [
"Thanks!",
"The link you have for isobutane is for isobutanol. Isn't that technically a different molecule? What does the extra hydroxyl group do to the absorption spectrum?"
] | [
"Yes you're right that link is wrong (and actually shows some significant absorption between 8-11 um!). Thanks for spotting that. ",
"This",
" is the correct link, showing the correct spectrum and the lack of absorption in that region. I found isobutanol as I was looking for isobutane and then muddled up the li... |
[
"Why wouldn't plasma propulsion work within the atmosphere of the earth?"
] | [
false
] | Well, the question in the title? Why wouldn't it work? What's the physics behind the not working? Not enough force to cause an action-reaction? Thanks in advance! | [
"It does work (sort of) but there are a few reasons why plasma propulsion is not used in atmosphere. ",
"The first part is that most the plasma propulsion systems used in space would not work as they are in higher pressure environment. Most of them rely on the fact that at low pressure there is less probability o... | [
"This is a great and comprehensive answer but I feel like many people will take away the wrong impression, like maybe we're just a few breakthroughs away from using plasma thrusters in aircraft.",
"Plasma thrusters are ",
" energy-inefficient compared to turbojets and turbofans. This is not a temporary obstacle... | [
"For a rocket engine, higher exhaust velocity means the engine uses less mass, but more energy, per unit impulse.",
"In space, mass efficiency matters a lot more than energy efficiency, since there is no way to get more mass, while there is plenty of energy from the sun or from nuclear power. So it is worth spend... |
[
"Is it true that no 2 snowflakes have the same pattern?"
] | [
false
] | And if it is, why is it like that? | [
"It depends how much difference you're willing to tolerate and still consider them the same"
] | [
"NewsBiscuit is another fake/parody news site, I'm fairly sure.",
"Edit: I posted that exact same article on Tumblr and found out the hard way :P"
] | [
"TLDR: ",
"There is a non-zero possibility that two snow flakes have the same exact pattern. It's however so close to zero that the answer is \"probably has not and probably will not ever happen, even counting snowfall on other planets in the universe\""
] |
[
"Is there an easy way to measure the relative strength of Iron or Copper in solution?"
] | [
false
] | When dying wool, copper or iron mordants are used and the down and dirty way of doing that is to get some scrap metal and put it in water for a while. To make the dying process more predictable, it would be great to have a way to measure how strong the solutions are. Does anyone here have any suggestions for how to do ... | [
"Yes, there are many methods",
". The simplest would be voltammetry and spectrophotometry."
] | [
"Thanks. I'm looking for something that a non-scientist can do without much or any special equipment. I don't need exact concentrations, but would like to be able to tell if one batch is about as strong as another."
] | [
"Turns out that ",
"aldrich",
" has test strips"
] |
[
"If you make the slits in the double slit experiment thinner than the width of the molecule your beam is composed of - does it still work?"
] | [
false
] | If you perform the double slit experiment with a large molecule - say you make the slits smaller than the minimum width of the molecule, will it still go through? Supposedly the largest molecule this has ever been achieved with was empirically C284.H190.F320.N4.S12, about 800 atoms. I can think of reasons for why this ... | [
"You want information about quantum tunneling, where an object can pass a barrier even though it doesn't have enough energy to persist in the space in between. In this case the molecule could usually squeeze smaller to fit through the gap, but this shape requires more energy than it has. There is still a chance tha... | [
"It is not tunnelling through the slit. In quantum mechanics \"particles\" are described by wave(function)s. Tunnelling is a property of all waves, it's called evanescence. The slit experiment is based on diffraction and interference. Entirely unrelated. The extent of the \"particle\" (wavepacket) is smaller t... | [
"You're confusing the positional uncertainty of the particle with the physical width"
] |
[
"Is there any animals that does not eat any plants at all?"
] | [
false
] | I know that cats and snakes are some of the obligate carnivores which means 70% of their diet are based on meat but, I read that both of these animals do eat plants for digestion. Also, I heard someone said that there has yet been any pure carnivores observed in nature? Is that true? | [
"The big cats will eat grass when they're having digestive problems, but I'm not familiar with any snakes doing the same. There have been instances where snakes ingest plants by ",
" like ",
"coastal cottonmouths eating seaweed because it smelled like fish",
". But outside of mistaken identity, I believe the ... | [
"Do spiders and carnivorous mosquitoes count also?"
] | [
"Well a spider would fall into the category of “probably gets a bit of plants from its food.” There are also some spiders, especially among the jumping spiders, that will drink nectar or even bite a stem from time to time, but most spiders are about like snakes in terms of how carnivorous they can be when eating th... |
[
"Why does stuff get preserved in amber?"
] | [
false
] | [deleted] | [
"That’s somewhat true, but it’s a sweeping generalization that cuts against the thrust of the question.",
"Things encapsulated in resin DO preserve better than their peers left exposed to oxygen and water. While it’s true that the exoskeletons of insects preserve better than the pulpy stuff inside, it is also tr... | [
"Stuff doesn't get preserved inside an amber completely. Only the shape of an insect and maybe a thin outside layer, stays intact. The inside of the creature is decomposed.",
"Ambers are basically like imprints, but in 3D."
] | [
"Amber keeps oxygen out. Many complex molecules, like the ones that at make up living things, would rather be broken up and bonded with oxygen than stay the way they are, which is one of the main reasons why things break down over time.",
"No oxygen, much less breakdown."
] |
[
"Why can't I graft plums branches to orange trees or nectarines to apple trees? Is a fruit salad tree possible?"
] | [
false
] | null | [
"The way grafting works is that you line up the cambium layers of the scion (the piece you're grafting) and the rootstock (the piece you're grafting it to) and the two pieces will behave as if the graft union were simply bark damage and heal over it.",
"But the pieces need to be closely related enough for the cel... | [
"different fruits of the same family",
"This is the key phrase. It is actually fairly easy to graft different varieties of the same family to the same tree. We used to experiment quite a bit with our apple trees."
] | [
"different fruits of the same family",
"This is the key phrase. It is actually fairly easy to graft different varieties of the same family to the same tree. We used to experiment quite a bit with our apple trees."
] |
[
"Does gravity travel at the speed of light? If the sun suddenly disappeared, would we still orbit it for a while?"
] | [
false
] | Does gravity travel at the speed of light or is it faster than light? (By disappeared I mean replaced with the standard empty space make-up) | [
"Here's the thing, the speed of light is not really just about light. The speed of light is the speed at which data propagates through space time. So yes, 'Gravity' or the progression of the forces of it travel at the speed of light.",
"I.E. If you have a star sitting in space, and then 1 light year away another ... | [
"Gravity doesn't \"travel;\" it's a curvature of spacetime which is simply present. But small changes in that curvature do propagate at c.",
"The fully correct answer to your question is that the Sun can't just disappear; that would violate all kinds of conservation laws. But if you ask the field equations that u... | [
"Not straight out as in radially, but straight out along the tangent to its former orbit."
] |
[
"Besides nitrogen fixing bacteria what other non-plants use atmospheric nitrogen?"
] | [
false
] | I've been trying to understand the nitrogen cycle, particularly as it relates to organic gardening. Compost, manure, various meals, etc get added to the soil to increase the levels of ammonia, urea and other nitrates in the soil. It is my understanding that most of that nitrogen came from directly or indirectly eating ... | [
"No plants or animals are capable of nitrogen fixing, nor are fungi or any other eukaryotes. The nitrogen gas in our bodies is inert.",
"Only bacteria and archaea are capable fixing N2 gas into ammonia or nitrate, forms that are metabolically useful. These include some cyanobacteria, rhizobia, Frankia, and free-l... | [
"No citations/sources for any of that? OP may like to at least read WP article on ",
"nitrogen fixation",
" and ",
"Diazotroph",
", both of which make it fairly clear that only bacteria and archea can fix atmospheric N, and also support your answer while giving further examples and context. Also while I'm h... | [
"Thanks for those links, very informative."
] |
[
"Can extreme tidal forces have an effect on the half life of an atom?"
] | [
false
] | So one of first thing people hear when they are told about black holes, is that they have the power to even rip apart atoms due to extreme tidal forces produced by the gravity. Well I was thinking is this somehow a linear capability. Say we have an Uranium atom orbiting an Earth mass black hole 2cm above the event hori... | [
"In principle: yes. In practice: well...",
"A very rough estimate: Tidal gravity scales with GM/r",
", the alpha nucleus would need to see something like 1 MeV/fm force over a distance of 1 fm. We get relevant tidal forces if GMm/r",
" = 1 MeV/fm",
" where m is the mass of the alpha particle.\nThe closest s... | [
"If you think 10",
" years is rather quickly: yes.",
"Edit: the parent comment was deleted, that time is the evaporation time from Hawking radiation."
] | [
"If you think 10",
" years is rather quickly: yes.",
"Edit: the parent comment was deleted, that time is the evaporation time from Hawking radiation."
] |
[
"What was the leap of insight that led John Bell to develop Bell's Inequalities?"
] | [
false
] | It wasn't until 1964 when Bell addressed the EPR paradox from 1935. Since the results of Bell's Theorem seem so counter-intuitive and he had no experimental evidence prior to crafting the theory, I'm trying to understand his thought process that led him to the theory. Basically why did it take so long before a physicis... | [
"For obvious reasons I can't tell you what John Bell was thinking, but we can look at his paper to see what he was reading that helped him formulate the ideas. In addition to the EPR paper, he was influenced by Von Neumann's textbook on the formulation by quantum mechanics, and another paper by ",
"Jauch and Piro... | [
"You could ask a very similar question about quantum cryptography and Shor's algorithm. These ideas could also have been developed in the 1930s, since quantum mechanics was certainly well-understood enough to have produced these results back then.",
"It's a matter of asking the right question, and questions are n... | [
"JS Bell's famous theorem took a long time, because John von Neumann published a proof (in 1932, I think) that hidden variables were impossible. Bell showed that the proof rested on an unwarranted assumption. See ",
"this",
".",
"Bell's book, \"Speakable and Unspeakable in Quantum Mechanics\", might help yo... |
[
"If you can see point B from point A, can you always see point A from point B?"
] | [
false
] | I'm having an argument with someone, please help me settle it. If I'm standing at location A and can see location B from where I'm standing, does that mean I will always be able to see location A from location B? What if they are at different elevations of vantage points or other factors like that. | [
"Assuming we're talking about vision, imagine there is a light source shining toward location B in an otherwise dark environment. You'll be able to see location B perfectly well from location A. However, from B, you may be blinded by the light, and thus unable to see A.",
"There's also the one-way mirror phenomen... | [
"Assuming you are talking about if photons are able to travel from A->B, traveling from B->A is also possible, the answer is \"not always\". For example in black holes there is nothing to stop the photon from entering beyond the event horizon, but exiting the event horizon isn't possible."
] | [
"Thanks for the answer! Those are both really good points!",
"Neither of us had considered something like that."
] |
[
"How is it that we can train our brains to 'think faster'?"
] | [
false
] | [deleted] | [
"Correct me if I'm wrong, but it sounds like what you're really asking is: What physically happens in your brain when you learn something? Because practicing something and become faster and better at it is really just a form of learning.",
"There is a saying in neuroscience that summarizes what happens: Neurons t... | [
"what you are describing is not an increase in speed but rather focus. Think of your computers task manager. While you are reading this your computer has a dozen of more things going on in the background. Now imagine you set the browser to be the most important program. Others have to run in the background still bu... | [
"Because the action potential goes at around 200m/s down the axon, which sounds fast but is a couple orders of magnitude slower than an electrical pulse going down a wire. ",
"Plus once it reaches the end it has to disgorge neurotransmitters across the gap to the next neuron to trigger it, slow, slow slow. "
] |
[
"Why does an ideal fuel:air mixture not burn completely, in practice? Why do the \"lean\" mixtures used in road vehicles not burn completely, either? Is there leftover oxygen, as well? If so, why is secondary air injection needed? Thanks."
] | [
false
] | [deleted] | [
"While the ratios of your input may be perfect, vaporization and actual physical mixing of the fuel and oxygen are never perfect. Think of it like a campfire. You have plenty of oxygen around to burn the logs, and plenty of heat. Why don't they combust immediately? It's because the reaction can only happen where th... | [
"Not just 'in contact', but at the correct pressure and temperature.",
"The gasoline-air mixture, starting at the spark plug, has to burn quickly enough to mostly burn when it is most mechanically advantageous, and when the chamber pressure and temperature are best suited for the burn...but not too quickly, or th... | [
"Modern catalytic converters have virtually zero performance penalty and the engine is probably even designed for the backpressure of the cat.",
"PCVs are commonly vented to atmosphere because the gasses contain oil mist and vapors that condense on the intake system. I've heard various nonsense excuses ranging fr... |
[
"Can cold welding, like when two pieces of metal touch in space, be achieved on earth in a vacuum chamber?"
] | [
false
] | Ive been reading about how cold welding can happen in the vacuum of space, but could it be achieved with a vacuum chamber on earth? | [
"Yes, although it's likely of limited use in an industrial setting, since vacuums are difficult to maintain. Friction welding would probably be preferred. However, a cold weld can be achieved without vacuum if you can apply enough pressure.",
"The reason for this is that metals in atmosphere have an oxide layer a... | [
"could you do cold welding by filling the area with an inert gas, like say argon, then you scrape off the oxide layer?"
] | [
"You'd be better off chemically reacting the oxide layer away. ",
"The inert gas would prevent new oxide from forming, and therefore could help the process, and may allow you to perform a cold weld without high pressure. For example, if you were working with a metal that would deform under pressure (say, copper).... |
[
"If carbon has a relatively short lifespan, how is new carbon created?"
] | [
false
] | Since carbon has a relatively short half life, compared to how old the universe is, why is there any carbon existing at all? | [
"Carbon 12 is the most abundant isotope of carbon. It is formed in stars through the ",
"Triple-alpha process",
". I believe that you are thinking of Carbon 14 which is used in radioisotopic dating. It does have a relatively short halflife, but it is continuously produced in the ",
"atmosphere",
".",
"... | [
"What you're thinking of is carbon 14, the radioactive isotope of carbon. It has a half-life of roughly 6000 years. It has 6 protons and 8 neutrons, and likes to decay into nitrogen 14, which is stable.",
"The most abundant form of carbon, however, is carbon 12. Six protons, six neutrons, completely stable, it co... | [
"I assume you're talking about the carbon 14 isotope, since most carbon (carbon 12) is stable. Heavy atoms in the universe were created in stars, long after the beginning of the universe, so comparing the halflife to the age of the universe doesn't make much sense. But either way, C-14 has a halflife of 6000 years,... |
[
"Is it possible for a magnet to disrupt activity in the brain? If so, how powerful would the magnet need to be?"
] | [
false
] | null | [
"Yes, it is possible to do this, and the magnet doesn't have to be all that powerful. ",
"Transcranial magnetic stimulation, or TMS",
" works by creating a strong magnetic field over the skull. The way in which this field is applied can be varied to either make the neural cells underneath the coil more or less ... | [
"What is it with reddit and wanting to hallucinate all the time?",
"Yes, but it's nowhere near what you think it is. The best you'll be able to do is to induce a ",
"phosphene",
". At best, it'll look like a shimmer, and it can be hard to actually detect a phosphene in the visual field because it is so subtle... | [
"What is it with reddit and wanting to hallucinate all the time?",
"Yes, but it's nowhere near what you think it is. The best you'll be able to do is to induce a ",
"phosphene",
". At best, it'll look like a shimmer, and it can be hard to actually detect a phosphene in the visual field because it is so subtle... |
[
"Why don't we use DC insted of AC in households?"
] | [
false
] | Wouldn't it be more practical and efficient to have just one big DC converter per household instead of multiple small ones since almost all devices run on DC (phone chargers, TVs, computers and so on)? | [
"It all comes down to the equations P = I*E and P = I",
" * R",
"The amount of energy lost to resistance in the transmission line is proportional to the square of the current. So there is an advantage to transmitting power at high voltage and low current. Once the power arrives at the home, you want higher cu... | [
"One issue is that many different pieces of equipment currently have many different requirements for total wattage, a singe dc system would still require dc to dc converters. so now you have multiple converters in on system. why would you need multiple converters bc your usb charger and laptop have different power ... | [
"For a desired given load expressed in Watts to be consumed at a residence/business you can deliver this power with any combination of Voltage(Volts)/current(Amperes) levels - where increasing one parameter decreases the other as expressed by P=IV.",
"Now, in the real world we deliver power over power lines with ... |
[
"Does a knee-jerk reflex happen while under anesthesia?"
] | [
false
] | Why or why not, and why would/wouldn't it happen while other functions continue? | [
"Yes and no, depending on the type of anesthetic used. Reflexes occur without conscious thought.",
"The patellar reflex or knee-jerk (myotatic) (monosynaptic) (American spelling knee reflex) is a stretch reflex which tests the L2, L3, and L4 segments of the spinal cord.",
"Mechanism",
"Striking the patellar t... | [
"The signal sent to your brain is actually not integral to the reflex. As explained above, reflexes are enacted by arcs that actually bypass the brain, allowing your body to act without the need for processing.",
"As to whether or not sensory signals are sent to the brain at all: it would depend on the anesthetic... | [
"That's really cool thanks. One more question; when this happens while conscious we notice the reflex, therefore some signal is sent to our brain correct? Is this signal still sent while unconscious?"
] |
[
"Why aren't all batteries rechargeable?"
] | [
false
] | [deleted] | [
"Batteries covert chemical potential energy into electric current by exchanging electrons from one electrode to the other, through the external load circuit (the device you are powering). ",
"There are two types of batteries: primary and secondary. In primaries batteries, when the electrons are passed between ele... | [
"How come you can charge some batteries and can't charge others",
"A lot of non-rechargeable batteries can't reform the anode/cathode, for example when these are lost in the electrolyte. Rechargeable batteries either keep the material on the cathode/anode (for example in lead acid batteries) or have a matrix as t... | [
"Reddit automatically formats lists from 1. You can kind of override this by adding a backslash in front of the number.",
"Rechargeable batteries tend to have a higher \"self-discharge\" speed, meaning that for very low power devices like tv remotes, non-rechargeable batteries can last over a year, while a recha... |
[
"Why do planets form in stable orbits?"
] | [
false
] | In general, not necessarily our solar system: Did a majority of the accretion disc directly form into the star and planets around it? Or are there innumerable "failed planets" that begin to form but do not have enough angular momentum to remain stable and they fall into the star. I imagine by its nature, the orbits are... | [
"So much time has gone by since they were created that the ones that formed in unstable orbits are long gone. Such as ",
"Orpheus",
"."
] | [
"The 'Asteroid Belt' was most probably a proto-planet torn apart by Jupiter's gravity. The remnants still follow a relatively stable orbit. Also, the hypothesized Mars-sized object that smashed into our nascent Earth and formed the Moon was a proto-planet in an obviously unstable orbit. chilehead is correct in that... | [
"Researchers are still trying to determine the extent to which the orbits of the planets are stable. The orbits of the planets are chaotic, and will deviate slightly and unpredictably from their orbits now, over the scale of tens of millions of years. chilehead has the right reason why they're almost stable. ",
"... |
[
"How much radio active waste (in kilos) does a nuclear plant leave per TW produced?"
] | [
false
] | As SpaceX seem to come closer to the holy grail of space launches, reusable rockets, price per kilo sent to space could drop rapidly in the coming years. Wikipedia mentions $200 per kilo, will we be getting close to be able to shoot the radioactive waste into the sun or is is still just not doable due to the cost? (Whi... | [
"It is not a good idea for a few reasons. One that you mention is mass. A typical reactor that outputs 1 GW(e) has around 30 metric tons of uranium fuel. About 1/3 of the fuel gets replaced every 18 months. So an entire core is replaced after about 4.5 years. That is a lot of mass you have to send up. Keep in... | [
"Thanks for the reply! And sorry about the unit failures. \nThe rocket disaster is of course a good point, when I googled this though there were some reports concluding that it would be possible to encapsulate it to be safe even in the case of a disaster. But that also add weights so it definitely adds up to the ne... | [
"Not an exact cost for disposal. The waste fund has well over $30 billion and is growing each year. Everyone pays 0.1 cents per kwh to fund nuclear disposal. ",
"As for Sweden, that is assuming running full power. The plant would not be economical if you ran at that low of power. Sweden consumes 153,000 TWh ... |
[
"If Cheetahs were extinct, would palaeontologists be able to gauge how fast they were based on their fossil record?"
] | [
false
] | And how well are we able determine the speed and mobility of other extinct creatures? | [
"Hey, I did my masters in the Animal Simulation Lab at the University of Manchester, this lab has been responsible for a lot of the well quoted estimations of dinosaur running speeds including T.Rex. ",
"I will first confirm what many have already said, if only the skeleton is preserved it’s quite likely that the... | [
"Many of these issues come up in trying to understand the extinct American Cheetah (Miracinonyx trumani), though at least there we have the comparison with living Cheetahs to help. There are various biomechanical ways to work out that they were likely quite fast from their bone structure, but also from seeing that... | [
"Most likely. You would probably be able to say that they were quite fast, although getting an idea of exact speed might be difficult. You can work out locomotor behavior for fossils by studying things like body plan, limb morphology and the details there of, the ratio of the hindlimb to the forelimb, limb to body ... |
[
"How did the notion of 3 meals per day come about? How do we know that it's good for us?"
] | [
false
] | This entire 3 meals a day things seems a bit arbitrary -- how did it come about and how was it determined that it's the optimal for human health? | [
"Meal frequency has no effect on metabolism. ",
"As can be seen here",
" - \"Studies using whole-body calorimetry and doubly-labelled water to assess total 24 h energy expenditure find no difference between nibbling and gorging\".",
"In ",
"this study",
", no differences were found between a lower (3 meal... | [
"We know that at least as far back as the Romans, three meals a day was the standard (this is in Adamson's ",
", and in others). Their three meals were the same as ours: breakfast, lunch and dinner.",
"It's hard to say what the eating habits were before that - it's a question that can really only be answered b... | [
"Working on construction sites, we would have two 20-30 minute breaks during the day, during both of which we'd have a proper meal. The combination of a long working day and high energy work meant that it made sense.",
"Working in offices, I have one smaller meal a day, and some snacks. ",
"These are cultural p... |
[
"Settle this argument please Reddit"
] | [
false
] | [deleted] | [
"If I wanted to know the latter i'd probably just visit ",
"r/trees"
] | [
"On a related note Drug dogs have a very high rate of false positives and are likely to be reacting to their controlling officer's belief regarding drugs rather than actually detecting them.",
"Here's a",
" link",
" at least to back up this result. I don't know of any \"official science\" papers supporting th... | [
"Can't offer any particular research, but I don't think it would be realistic.",
"The concept of \"scent molecules\" is dead on. All the substances you are thinking of release some sort of reasonably small molecule with enough vapor pressure that they tend to rise into the air and travel. They travel all over, bu... |
[
"What gives the Squid nebula its stretched oval shape?"
] | [
false
] | Hey today on they were showing this picture made buy Rolf Geissinger of the Squid Nebula: What gives the nebula this shape? To my untrained eye it looks like the red cloud is some kind of super nova remnant. kind of like the other one around the star at the bottom left-middle of the picture. Then there is the central b... | [
"This paper",
" reaches the conclusion that it it's not energetic enough to be a supernova, and is likely to be a wind or outflow, probably due to an interaction in the central ternary system.",
"More specifically, a slow wind has been emitted from the system for a while, but more recently (~90,000 years ago), ... | [
"Thank you very much. That is cool."
] | [
"Noob question: by wind, you mean solar wind right?"
] |
[
"Why do charred foods become carcinogenic? I have seen warnings at fast food restaurants that their fries can cause cancer, so... why?"
] | [
false
] | [deleted] | [
"The details are extremely messy, but the principle is fairly simple. Food, like all organic matter, has a huge number of complicated (and rather fragile) organic compounds in it. If you heat it up enough it'll start burning, decomposing into smaller molecules that vaporize and are further combusted into CO2 and wa... | [
"Acrylamide is the issue with French fries, not PAHs like you mentioned. "
] | [
"Thanks, yes I live in CA, which asks places to label anything that has even insignificant risk. I saw the cancer warning at Wendy's once.",
"Thanks for your detailed explanation. "
] |
[
"Can we effectively stabilize the ocean's fish population through fish farms? Or do we have to slow the amount of fish being harvested and let them repopulate?"
] | [
false
] | null | [
"The factors effecting the ocean's ecosystems are multifactorial and fish farming only attempts to solve one of those factors: over fishing. Just for background (I don't know how much you know). ",
"Fish are renewable resource so long as we don't take more then they be can replenish - in the same way trees are re... | [
"There are some good examples of sustainable fish farms though, particularly species such as tilapia or catfish as they feed lower on the food chain than other commonly farmed fish such as salmon.",
"One more thing we can do to reduce overfishing is the over-capitalization of fish fleets. Many fleets have too man... | [
"Yes we are overfishing, climate change is also wreaking fish stocks as is pollution.",
"Fish farms aren't magic bullets either. \nBasically The most easy to understand reason why we have screwed future generations "
] |
[
"Why is a lunar eclipse not red until near totality?"
] | [
false
] | If we look at the time course of a lunar eclipse e.g. , the shadow that falls over the moon isn't always red. It looks like you get a normal shadow until around the 10th picture, where we're pretty near totality, and only then does the red light (from refraction through the atmosphere) become apparent. Why is it not al... | [
"The red light is always there when the moon is in Earth's shadow. But the red light it is dim and drowned out by the direct sunlight that hits the moon. You can see a sudden transition in the second row, on the right side. That transition does not happen in real life. It's the camera doing that.",
"The sequence ... | [
"This is part of the answer. But the moon is actually more red the closer it is to a totality. The red color is sunlight that has passed through earth's atmosphere, been scattered and lost most of its blue color. In this way, the red color is light from Earth's sunsets and sunrises reflecting off of the moon. When ... | [
"I thought this might be the case, but when watching it the other night, I saw the same effect. Maybe the same happens with the eye though, that the red is drowned out by the fully illuminated part?"
] |
[
"Medically, what happens if you get shot or stabbed in the heart?"
] | [
false
] | I looked up on the internet, but I was unable to find a satisfactory answer, or variations for piercing specific parts of the heart. Essentially, what happens phase by phase, when one's heart is stabbed/shot? I am not psychotic, I am just a writer. | [
"FWIW, that procedure has a survival rate around 1%. I think the chain of events in that case report (from injury to survival in the OR) mounts to nearly 1 in a million odds.",
"Here is the course of events:",
"1) Penetrating trauma. Mechanism of injury passes through chest wall, +/- lungs, pericardial sac and ... | [
"Depends. If some one took a battle axe to the left ventricle, they would not be alive for very long and they would stop perfusing their brain very soon (dozens of seconds to a few minutes)",
"EDIT: the most acute tamponade I've seen (out of 3) was: \"My chest hurts\", grabs chest, bends over to use his other han... | [
"Here's an article about a woman whose heart was lacerated in a car accident, but lived long enough to be saved in the ER:",
"http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1477483/?page=1",
"Hope that helps."
] |
[
"propagating sigmas from Poisson and Gaussian"
] | [
false
] | [deleted] | [
"By sigma you mean variance? What do you want to propagate?"
] | [
"The Poisson Distribution is not a continuous distribution as is the Gaussian (normal) distribution, it's discrete. Therefore a given sigma value for a Poisson distribution only approaches that for a Gaussian distribution as the number of samples approaches infinity.",
"In general, a sigma value from a Poisson di... | [
"I was rather convinced that said error propagation assumes Gaussian distributions. What are you trying to do? Why are some of your errors Poisson distributed?"
] |
[
"Why use cDNA rather than mRNA?"
] | [
false
] | Why is it that labs use cDNA when investigating genes? What is the advantage over mRNA? Is it possible to use mRNA instead? If cDNA is patentable, which it seems that it is after the recent ruling, could mRNA be used as a substitute? | [
"The lab I worked in was using cDNA for a few reasons. We were interested in sequencing mRNA, and the only reasonable way to do it is through cDNA. ",
"PCR",
" works on cDNA, high-throughput sequencing works on it in the normal way, and DNA is much more stable than RNA.",
"cDNA is also useful if you have ... | [
"CDNA lasts a long time ... rna is readily degraded ... that's the biggest reason."
] | [
"It's actually a combination of the increased stability and the greater genetic tractability of cDNA. For example, most modern sequencing technologies -- including those that are used to look for mutations in the BRCA-1 and BRCA-2 genes -- are designed to work on DNA only (including cDNA, but excluding mRNA)."
] |
[
"Can anything be derived from handwriting (mood, personality, character traits...)?"
] | [
false
] | [deleted] | [
"Wikipedia entry for ",
"graphology",
"."
] | [
"I used to say bullshit to this, but I once submitted my signature to a computer that scanned it in and then printed out a sheet with 16 character traits and it was eerily accurate - from what I remember, \"Intelligent\", \"Can be lazy\", \"Impulsive\", \"Doesn't think before speaking\" etc.",
"I have a scan of t... | [
"It's really easy to produce a bunch of words or descriptions which either play off individual's pride or can be applied to most anyone. Additionally you can make some general guess about someone who would put the effort into submitting a signature to a computer."
] |
[
"[Physics] Do I gain mass when i am higher up?"
] | [
false
] | I of course remember learning that you gain potential energy as you rise in the air, equivalent to E=mgh. But since E=mc would you gain the slightest bit of mass by at the same time? Follow up question if yes, how would that mass be stored? Is it just stored as energy? | [
"It's not ",
" specifically that's gaining mass, it's the entire ",
".",
"You and the Earth are bound together by your mutual, attractive gravitational interaction.",
"When you increase your altitude, you are increasing the potential energy stored in the system, and thus increasing the mass of the ",
".",... | [
"If I heat a waffle, does the waffle itself have more mass or does the system of vibrating waffle particles have more mass relative to my own change in mass?",
"If your system is just a waffle, and you increase the internal energy of the system, you have increased the mass of the waffle."
] | [
"When you increase your altitude, you are increasing the potential energy stored in the system, and thus increasing the mass of the entire system.",
"Only if you use some external power source, e. g. the Sun, to do so. If you spend internal energy (walking upward, driving a car, whatever), the total mass is conse... |
[
"What does a wild animal do when it is safe, warm, and full of food?"
] | [
false
] | Once an animal's basic needs for survival are met, how does it spend its time? Do animals try to amuse themselves? Do they get bored? | [
"Well of course it would look for a mate. Once the mate is found and they've done the process of mating, what happens next is really up to the species and gender of it. "
] | [
"You forgot one: looking for a mate."
] | [
"Say it's a carnivoran, and it's not mating season. What would it do in that case?"
] |
[
"Will the duration of the average human life ever be a barrier for progress?"
] | [
false
] | I was thinking the other day of how no more than a couple hundred years ago it was possible to be an expert in almost everything. One could be a leading physicist, mathematician, astronomer, biologist, engineer, artist, philosopher, and a prolific inventor to boot. A lot of the reason for this was simply the relatively... | [
"This is an interesting question, but I don't think anyone can answer it definitively. An important factor is that being a jack of all trades and being able to make progress is not the same thing. Furthermore, it takes far longer to find new ideas to make progress than it does to learn things that have already been... | [
"There's an excellent short story by Asimov called ",
"Profession",
" about this. I won't give away the ending though."
] | [
"Nah. Exponential growth in human knowledge will be handled by increasing specialization and increasing human lifespan. Who cares if it takes you 100 years to learn a subject if you can replenish your telomeres indefinitely and keep flushing old cells out for replacements derived from stem cells and gametes? The... |
[
"I was recording myself in my sleep last night and it got me thinking, what decides why we change sleeping positions while we're sleeping?"
] | [
false
] | Why does the sleeping brain change our sleeping positions? Is it because it's starting to get uncomfortable or anything else? | [
"The body has a number of bony prominences, which are areas where bone comes up close to skin level, such as the heels, the sacrum/coccyx, and the shoulder blades. As you sleep immobile, pressure builds on the skin beneath these bones and will eventually cause pain, numbness and then skin tissue damage/death if the... | [
"Are these what are known as 'bed sores' or is that something different? "
] | [
"Same thing."
] |
[
"How does the weak force works ?"
] | [
false
] | I manage to understand the other 3 interaction but the weak force still remains a mystery, i was wondering if you van answers these following questions: 1. What are the mechanism of the weak force ? 2. What field of boson transmit it ? 3. How does the weak force affect our lives ? 4. Can or Have we harnessed the weak f... | [
"The force carrier particles for weak interactions are the W and Z bosons. There are three of them: W",
", W",
", and Z",
" (the superscript denotes their electric charges).",
"The W bosons mediate so-called \"charged current\" interactions, while the Z boson mediates \"neutral current\" interactions.",
"... | [
"Ionization smoke detectors use alpha-emitters rather than beta-emitters. Alpha decay is not caused by the weak force."
] | [
"My whole life has been a lie.",
"Sorry, OP - try ",
"PET, ",
" which is used in hospitals worldwide."
] |
[
"If the Earth was not following a circular path, would we feel a change in normal force throughout its path?"
] | [
false
] | For example, Pluto, it follows an elliptical path. If you were standing on Pluto and measured your weight/normal force, would there be a difference in that value between the point in time at the curve, and the point in time at the more, relatively straight path? Now, in terms of Earth, lets say some other gravitational... | [
"If you performed very careful measurements, you would notice small differences in your weight",
"Earth is in freefall around the sun, so despite the gravitational field varying through Earth's orbit, one's weight would not change due to this field gradient.",
"So for OP's questions:",
"If you were standing o... | [
"The Earth does not follow a circular path, our orbit around the sun is an ellipse, with eccentricity 0.0167 (for reference, ellipses have eccentricities between 0 and 1, 0 being a perfect circle, 1 being the limit case, a parabola), so it's almost circular.",
"If you performed very careful measurements, you woul... | [
"Ah so there is a change. Interesting. And thank you for that correction."
] |
[
"Why does Earth have so many Islands, and why are (so many) so flat?"
] | [
false
] | I've recently found bathymetric data interesting and as a complete nooby it has occurred that islands are actually rather weird once you consider the underwater portion. : . Go to any in the Pacific and you'll see what I mean. (In Google Maps, use satellite view to see Ocean's Surface) With that said, it seems highly c... | [
"So there are a couple of different things going on. ",
" Importantly, there is a decent amount of confirmation bias here. Specifically, there are ~440 ",
"atolls",
" (i.e., ring shaped reefs built on top of submarine volcanoes) and ~283 ",
"guyots",
" (i.e., flat topped submerged volcanic mountains), but... | [
"Piggy backing on the comment about sea mounts. Helen scales wrote a great book for the layman called the brilliant abyss. It goes into great detail about sea mounts not breaking the surface of the ocean but still being incredibly diverse hot spots for life, acting like an under water island. So even in terms of b... | [
"Thank you for the detailed answer! The part about Sea Mounts I found especially interesting. And the effect of coral is also very interesting."
] |
[
"What makes a gas giant different from a star?"
] | [
false
] | [deleted] | [
"Stars are denoted by the production of energy through sustained fusion. Fusion in stars is triggered by immense gravitational pressure, so you have to be above a certain mass threshold to have a star. Basically, gas giants are too small to trigger the process."
] | [
"Babyyyy you're a whiteeeee dwarf.... come on let your fusionnnnn burn..."
] | [
"Size and process of formation.",
"Stars condense directly from pre-solar nebulae. Planets accrete from proto-planetary disks around young stars.",
"Gas giants likely all have rocky/icy cores due to their formation processes, whereas stars, even brown dwarfs, don't have solid cores.",
"Currently we call anyth... |
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