title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"What would happen to my body if I were hit by an atom from an atom smasher?"
] | [
false
] | Lets say I was able to stand in front of the path of an atom traveling at Large Hadron Collider speeds. Would it obliterate my body to pieces or would the atom pass through my body without incident? Thank you guys a lot, extremely informative. So from has been said; a single proton would most likely have 7 TeV of energy; which would likely cause no damage at all, or even pass right through you as many particles do constantly. I have also learned that particles can be used at high speed in a medical oncology as a form of cancer treatment. I think I shall go out under the stars tonight and bathe in the particles raining down from space! | [
"As a researcher at the Institute for High Energy Physics in Protvino, Bugorski used to work with the largest Soviet particle accelerator, the U-70 synchrotron.[2] On July 13, 1978, Bugorski was checking a malfunctioning piece of equipment when an accident occurred due to failed safety mechanisms. Bugorski was lean... | [
"This happens to you already, all day every day. We usually call subatomic particles freely traveling around by another name - radiation. You are exposed to radiation every second from the ground, the air, the walls of your house, and space.",
"The protons in the LHC have 7 TeV, which is a unit of energy. This... | [
"Yes, this story never fails to be brought up whenever anyone asks anything related to human exposure to particle accelerators. This example is really only applicable if we are talking about massive cranial exposure to radiation. The OP is asking about the effect of one particle, which is so small as to not be no... |
[
"Given that the majority of calculations performed by a computer are some sort of matrix inversion, solution of a linear system equations, or solving some partial-differential equation, are there known Quantum Computer algorithms that actually provide speed-up for these problems?"
] | [
false
] | null | [
"but quantum many-body calculations are only the tiniest sub-set of the numerical calculations that we do in our society.",
"For now, because they are hard to do.",
"Quantum computers are not supposed to replace classical supercomputers. They are supposed to supplement them - take over some work that is difficu... | [
"Your statement about the types of computations being done on computers isn't really accurate, but even if it was, it's missing the point. Quantum computing has the potential to revolutionize a few specific areas of computing that are really important, which is enough to be interesting and worthwhile, even if it wo... | [
"You're taking one of the most high-profile uses of quantum computing and saying it doesn't matter. Of course you're going to be left saying that quantum computing doesn't satisfy. If you've already decided (against the general wisdom) that these things don't matter then I'm not going to be able to convince you, bu... |
[
"Would a microwave heat up heavy water (deuterium oxide) just like regular water?"
] | [
false
] | I tried to find the answer on Google but couldn't come across anything. | [
"Yes, they have almost the same electrical dipole moment. It wouldn't be ",
" the same, since H2O and D2O have ever-so-slightly different properties (specific heats and so on), but that applies no matter how you heat them."
] | [
"Generally, no. The heat capacity of an ideal gas is independent of the weight of the gas molecules. For noble gases it's 20.78 J/molK for Helium and 21.01 for Xenon, and the latter weighs 32 times as much as the former. ",
"The difference between H2O and D2O is more indirect, as the relative difference in mass b... | [
"It's not a misconception. Water is usually the part of your food which absorbs the majority of the radiation. The relative permittivity of wafer is ~80 whereas most plastics are around 3."
] |
[
"How can super low frequencies of electromagnet radiation (eg. radio waves) and super high frequencies of electromagnetic radiation (eg. gamma rays) pass through walls, but the frequencies in between can't?"
] | [
false
] | null | [
"Has to do with the wavelength. High frequencies have short wavelengths, small enough for the electromagnetic waves to pass through the empty space in the matter. This is why high frequencies are damaging to living cells - the wavelength is literally short enough to pierce DNA like a knife, slicing it apart.",
... | [
"Don’t photons need exactly the right amount of energy to be absorbed by an atom? Is it not because the atoms in the wall just don’t accept the specific frequency of the light?"
] | [
"Yes! There are specific sets of wavelengths (or frequencies, or energies if you like) that any given atom can absorb. Because these are specific, explicit sets of energy levels, we call them ‘quantized’, which is when quantum mechanics was born out of. (Very simplified, but it’s the idea). "
] |
[
"Is there a uniquely \"Human\" protein, or a unique aspect of a Human protein that exists in humans and no other species?"
] | [
false
] | Asking for a television script I'm writing. Thank you! | [
"Sure, though it depends on exactly what you mean by \"unique\". ",
"Bitar et al. 2019",
" examined over 800 genes with at least some human-specific features, and might be a good resource to read further into. Probably unsurprisingly, ",
"a lot of them are known or predicted to be involved with the nervous... | [
"Thanks for the sources you listed! That's incredibly interesting."
] | [
"You might be curious to know that author and former marine-mammal biologist Peter Watts explored this idea in his book ",
"Blindsight",
". The full novel and copious background notes are ",
"available online from the author himself",
". There's also a short ",
"in-universe lecture on the subject",
". (... |
[
"When a person suffers a severe case of amnesia, will they have interests in the same things that they had before their amnesia?"
] | [
false
] | null | [
"It depends. Retrograde amnesia (the most common type of amnesia) only impairs ones memory for events. Skill related memory (muscle memory) is not affected. That is why a person with amnesia can still speak English.",
"So, if ones preferences come from a particularly traumatic event, then they might not have the ... | [
"The area of the brain thought to play a major part in sexual preference--a subregion of the hypothalamus--is not involved in conscious memories. Also, it's a wiring thing (disclaimer, believed to be), so not really something that can be forgotten. There is some evidence (in lab animals) that you can lesion this ... | [
"how about sexual orientation, is it possible for one to forget that he is straight, or vice versa and forget he/she is gay?"
] |
[
"If you remove a verruca/wart from your body, does that remove the virus, or will it always remain in your system?"
] | [
false
] | [deleted] | [
"No, because I don't have genital warts. I have a verruca on my foot that's about 2mm across."
] | [
"I'm consulting ",
"/r/askscience",
" because I want a serious "
] | [
"Don't get your warts in a bunch, I was just kidding. Perhaps you should consult a doctor if you want a a serious opinion and can't take a joke."
] |
[
"AskScience AMA series: I am a neuroscience researcher who pokes brains all day."
] | [
false
] | I'm a postdoc doing basic research into auditory brainstem and olfactory systems using electrophysiology and laser imaging techniques. I have a free evening and a bottle of wine. I'll be hitting F5 periodically so go nuts. Edit: The questions seemed to have dried up so I'm for bed. If there's anything else, I'll get to it on the morrow. Thanks for a nice evening reddit! Edit 2: after a nice long sleep I'll be around sporadically today if there're any more questions, so feel free to AMA else. | [
"It's a cliche but - the brain. It's just really amazing. The way millions of tiny subcellular processes are going on constantly within every cell (neuron and otherwise). Each neuron is connected to an impossibly complicated network via hundreds or thousands of synapses. Each part connected just so so that you can ... | [
"I did a bachelors degree, then a masters and a PhD. Then I looked for post-doc positions. I guess I never really left university ;)",
"Pay isn't great (I work at a university), but I'm doing ok."
] | [
"Can you explain in more detail what you do? And what questions you are examining?"
] |
[
"Does a strained rubber band have more mass than an unstrained one?"
] | [
false
] | null | [
"Does a strained rubber band have more mass than an unstrained one?",
"Yes, very slightly."
] | [
"How is that shown though? How much mass would it gain "
] | [
"It gains a mass equal to the elastic potential energy, divided by c",
"."
] |
[
"Is it possible for a Plesiosaur breeding population to live in a large lake?"
] | [
false
] | Disclaimer: I am NOT a cryptozoologist! All I wan't to know is: Is there enough food and habitat in a lake of similar size to Lake Champlain or Lake Oakanogan to support a breeding population of lake monsters? | [
"Absolutely, I'll do so tomorrow evening when more people are online. I have no idea why all my questions are snared in the spam filter, but I really appreciate the help."
] | [
"I know we have some panelists that would probably love to answer your question!",
"I went ahead and approved your question, and gave you an upvote, but since you posted this 6 hours ago, you might have better luck posting it again.",
"If you decide to repost it, shoot me a PM and I'll approve it for you!",
"... | [
"I have my doubts. The best analogy might be with marine mammals...they share the closest niche. And only extensive river systems hold breeding populations of dolphins. Lake Baikal has a breeding population of seals, but lake Baikal is ",
". And note that both dolphins and seals are quite a bit smaller than t... |
[
"Can carbon dating be affected by unusually high levels of radiation during a certain time?"
] | [
false
] | I understand that carbon dating is the measurement of the degradation of Carbon14. If, in the case of human remains, an individual received extra radiation due to atomic bombs, mercury poisoning, etc, could that skew the dating process? This is not a creation/evolution related question. | [
"Heck yes.",
"C-14 dating has been noticeably impacted by human-produced C-14, mostly from nuclear testing since the 1950s. People who actually do C-14 dating use a ",
"calibration curve",
" to adjust the naïve results given by their tests to better match the actual history of C-14 production on our planet. T... | [
"C-14 decays by beta emission, which occurs with basically a continuum of energies up to 149 keV ",
"(link)",
". If you were using a geiger-type counter (which can't determine the energy or type of radiation) to determine the sample's radioactivity, then absolutely any other ionizing radiation would trigger the... | [
"To add to this, mass spectrometry is often used for C-14 dating like you said, where the measurement doesn't rely on release of radiation but rather the amount of C-14 can be quantitatively measured. This is typically done with some version of a particle accelerator like a cyclotron so that rare isotopes to give b... |
[
"How much resources do huge AIs like AlphaGo and AlphaZero take up?"
] | [
false
] | Just wondering exactly what it takes to run these very strong AI program that can learn to beat world champions in a matter of hours. I don't actually know of any other big/commercial AIs, but feel free to mention anything! | [
"When they defeated Lee Sedol, those components were replaced by 48 TPUs. (Tensor Processing Units optimized for neural networks)\nAlphaZero only uses 4TPUs."
] | [
"I read the paper and answered my own question.",
"\"AlphaGo uses an asynchronous multi-threaded search that executes simulations on CPUs, and computes policy and value networks in parallel on GPUs\""
] | [
"I don't have a complete answer for you, but AlphaGo in particular has two variants implemented:",
"quoted from their Nature paper ",
"here",
". They both played with a 5 second 'thinking time' per move (\"Extended Data Table 6\")."
] |
[
"Can intermittent light be as effective as continuous light for plant photosynthesis?"
] | [
false
] | Lets say you had a plant grow under a light-bulb that was on continuously for 8 hours and a plant under a bulb that was on for a second/off for a second for 8 hours ( for a total of 4 hours of light). Would the later plant be similar to a plant grown under continuous light of 4 hours? Lets say you had the same experiment but the light that switched on and off was doubled in intensity (so the plant gets roughly the same energy of light as the continuous 8 hour bulb only via double intensity bursts.) I suppose the root question i'm asking is if you only have X units of light (lux?)(sorry dont even know what the right word is) to give to a plant whats the optimum way to deliver it? | [
"Let's consider your first example, where Plant 'A' is grown under conditions in which it is exposed to eight continuous hours of light and where Plant 'B' is flashed with light for eight hours, but receives half amount of light energy. In this scenario, both plants will absorb different amounts of light, but expr... | [
"Here's some neat stuff I summarized about plant responses to high light intensity!"
] | [
"Thank you! This is an amazing answer to which i have no follow up questions!"
] |
[
"How much energy/heat does the moon block from reaching the Earth during a solar eclipse?"
] | [
false
] | The moon is blocking sunlight from reaching a small portion of the Earth during a solar eclipse, so how much energy does it actually block that would have otherwise traveled to the earth? Could an eclipse cause a measurable difference in temperature on the Earth? | [
"If the eclipsed area has a radius of 100 km and lasts 7 minutes, and the sun gives 1460 watts/m",
" , that's about 2 x 10",
" joules blocked.",
"If it blocks a 100x100x10 km region of the atmosphere, according to my rough calculations it should drop about 6 degrees, but I'm not sure that's accurate."
] | [
"I don't think too much apparently ",
"http://www.aaadelhi.org/files/eclipse99_mir_big.jpg"
] | [
"Yes, because everyone knows how stuff freezes over every night only a few minutes after sunset, even in summer in the Bahamas."
] |
[
"r/AskScience, I have a question about odds.."
] | [
false
] | Is there a way to calculate random events? Or is there no such thing as a random event given the proper information and time to process? For instance, if you were breaking in a game of pool and the balls traveled at exactly the same speed until they went in a pocket would you: A. Be able to calculate the exact time it takes for all the balls to fall in a pocket? B. Be able to calculate which ball falls in which pocket? I'm not asking to actually do those calculations, but I want to know where modern science sits on be able to predict random occurrences. | [
"No, there is no way to know exact positions and exact behaviour (momentum, a measure of motion) simultaneously. In fact, you can think of the universe ",
" things don't ",
" exact positions and momenta. We've even accounted for the fact that \"well suppose there ",
" something but we don't know how to measur... | [
"So the two calculations you suggested aren't actually random. They are going to depend on a lot of different factors.",
"The easiest scientific example I can come up with is radioactive decay. Say you have a lump of uranium. We know it's going to decay but can't accurately say, ok...one decay will happen ",
".... | [
"True randomness is unpredictable by definition. If we were able to calculate a random event then the event would not be, in fact, random.",
"For your question about the pool scenario, the answer is yes. Although the calculations would be extremely tedious using fairly basic physics of angles and momentum one cou... |
[
"If honey bees aren’t native to North America, why aren’t they treated like other invasive species?"
] | [
false
] | null | [
"As a bee researcher, I have to say I disagree with several of the answers here to varying degrees. But to first address your initial question, honey bees are treated differently in North America because they are essentially livestock. There is at least some evidence that people were intentionally managing honey be... | [
"Honey bees are one of the few non native species that have become “invasive” that we’ve introduced that don’t have cons that outweigh the pros, so to speak.",
"As a matter of fact, many types of modern agriculture DEPEND on pollination from honey bees.",
"They are incredibly precise individually and amazingly ... | [
"I don't know how beneficial honey bees are outside of pollinating large agricultural fields. Honey bees are invasive and displace native bees that have evolved to pollinate specific types of native pants. I think they are treated differently because they produce honey which is a commodity."
] |
[
"What is actually going on in those salt-on-a-vibrating-plate \"resonance\" demonstrations?"
] | [
false
] | null | [
"Vibration of plates occurs in a predictable fashion based on the boundary conditions of the plate, the properties of the plate, and the induced vibration. The sand or rice or salt or whatever will tend to accumulate in regions of low displacement and leave regions of high displacement because it will get \"tossed... | [
"If you had the salt on an infinite plane, and put vibration under it, the wave would expand in circles.",
"When you instead do it on a square plate, the properties change when the wave reaches the edge of the plate in one area, but is still moving into the corner of the plate in another. ",
"The wave essential... | [
"Let's simplify this and just look at a sine wave for a second.",
" Imagine a string that is excited in that manner. If you were to first place sand evenly across the top of that string (ignoring the fact that it would all fall off), where would the sand go? It would be pushed away from the points with maximum di... |
[
"Rather than retiring the last two space shuttles on Earth, why aren't they being permanently integrated into the ISS?"
] | [
false
] | My impression is that they are still perfectly spaceworthy, with re-entry posing the only significant danger. Considering they have fully-functional life support built in, not to mention the massive expense inherent in building and deploying new space station modules, why not give the shuttles a permanent home in orbit where they can continue to serve a useful purpose? | [
"I'm going to guess that a) it's because the space shuttles are designed to be in space for a period of a few days only, b) the space station has a limited number of docking ports and they can't really spare them, and finally, c) the altitude/attitude control thrusters on the ISS weren't designed to handle the extr... | [
"Well, they're already 30+ years old. Aside from wear and tear, they must be filled with a lot of obsolete equipment. Plus keeping them up there and turned on has got to take power, which they probably don't have a whole lot of. "
] | [
"I think smhinsey is talking about using them for stationkeeping. Use them for thrust to keep the orbit from decaying. ",
"This is currently already done by the zvesda or whatever the hell it's called though...so I don't see why they need more engines. ",
"Regardless, it's a moot point. The plan of de-orbit... |
[
"Does the surface of the Earth \"flatten out\" to any extent due to space-time curvature?"
] | [
false
] | I apologize, I know it sounds like a stupid question. I'm thinking of that pithy line, "mass tells space how to curve, space tells mass how to move." I remember visual gravitational models that suggest that heavy astronomical objects acts a little like dimples on a canvas, drawing objects to them and "curving" straight line motion. My question is, how does this apply to us here on Earth, much closer to the center of our planetary mass? Do we perceive the Earth as more "flat" because of this? EDIT: awesome! Thank you all for your comments. I'm absolutely fascinated reading through them. You invested some real time explaining this to me and I really appreciate your effort! | [
"The answer is yes or no depending on exactly how you phrase the question. Let me explain:",
"Let me just specify first that these effects are ",
". Basically Earth's mass curves spacetime, sure; the components of curvature relating time and space are pretty large and are what gives you the gravitational force,... | [
"Well, what do you expect? You cannot fit the normal flat-space Earth, with A=4π R, in the curved space created by its own gravity - you need to change something. Either you keep the radius fixed and make the surface area smaller than 4πR2 to accomodate, or you keep the surface geometry fixed and increase the radiu... | [
"What would you say about the intuition that, if you lie near the photosphere around a blackhole (where the geodesics are closed), you can are going essentially \"straight\" while remaining on near sphere. Which would imply the area of the photosphere is 0 (which is not the case?), so is the problem in the definiti... |
[
"A little simple, but- Why do basketballs bounce so hard when they hit a corner?"
] | [
false
] | If you've ever dropped a basketball, or any other kind of bouncy ball on an edge or corner, you know what i'm talking about. Why do they do this? | [
"Why does this matter, though? ",
"The ball is carrying the same amount of energy whether it hits a corner, edge, or flat plane. My instinct would be to say that there should be no difference in total \"bounce\": in hitting a flat plane, you use the ball's energy to cause a larger section of the ball to deform an... | [
"A good basketball will rebound off the floor with ",
"about 75%",
" of its original energy. Hitting a corner can't do more than 33% better than this under any circumstances."
] | [
"The quastion was, \"Why do basketballs bounce so hard when they hit a corner?\" I was simply pointing out that they can't bounce more than 33% harder than from a flat surface without violating conservation of energy."
] |
[
"How do we communicate with satellites?"
] | [
false
] | Motivated by about dropping pictures. Satellites are essentially computers in space, correct? Do normal actions apply? Can I "drag n drop" an image by connecting remotely? | [
"Modern satellites communicate via radio waves. If you have an antenna or dish with the correct shape and electronics, you can easily receive the signal sent by the satellite. With a similar or larger dish correctly positioned you could probably send a signal to the satellite, but you would need the correct code/pa... | [
"Satellites are essentially computers in space, correct?",
"This is arguable, because they have lots of systems/devices that are not computers. But if you say they ",
" computers then yes, your assumption is almost correct.",
"But it's computers understood like an electronic circuit that has a processor, memo... | [
"That depends on each particular case. Probes going very far away in interplanetary space sometimes do not have any security at all, simply because the parabolic antenna needed to communicate that far is not something that a hacker may have in his garage (actually I asked this to a professor who works in the indust... |
[
"I always read about the diseases western Europeans settlers brought to American when they settled here wiping out Native Americans. Why didn't these diseases exist in NA?"
] | [
false
] | Did the Native Americans have other diseases to contend with that were more specific to that region? If so, did those affect the Europeans? I never hear about diseases in Native American culture pre-colonization, which makes me wonder if the lack of industrialization in NA made it less of a breeding ground for diseases | [
"Native Americans did have their own set of diseases to contend with actually. It's been ",
"addressed previously",
" in ",
"/r/AskHistorians",
". People here like to cite the recent CGP Grey video, despite it just summarizing Jared Diamond's book ",
", which has been widely criticized by historians and a... | [
" is a funny one, in that it caused a number of major plagues amongst the indigenous inhabitants of Mexico, some leaving whole towns with nobody alive to bury the dead, and yet it didn't seem to affect people of Spanish blood. Spanish monks were closely involved with the sick and the dying, yet never seemed to catc... | [
"thank you!"
] |
[
"what does \" no two electrons in the universe can have the same energy state\" actually mean?"
] | [
false
] | Does it mean there are an infinite levels of states an electron can be, like an infinite rungs on a ladder? | [
"This is correct. The four quantum numbers specify the \"address\" of the electron within an atom. No two electrons can hold the same probabilistic model specified by the quantum numbers within the same atom. However, electrons can absolutely hold the same quantum numbers in different atoms. Not sure if this is... | [
"This is correct. The four quantum numbers specify the \"address\" of the electron within an atom. No two electrons can hold the same probabilistic model specified by the quantum numbers within the same atom. However, electrons can absolutely hold the same quantum numbers in different atoms. Not sure if this is... | [
"It should actually be \"have the same state\". Energy or not doesn't matter.",
"The state of any quantum system is a normalized vector in a Hilbert space (well, it's typically called a ",
", but they're essentially interchangeable). Like a normal 3-d vector, we can describe this vector by a list of numbers ... |
[
"Why do people with Down's Syndrome look very much alike?"
] | [
false
] | [deleted] | [
"I won't bore you with the specifics regarding aetiology, but essentially Down's is due to a an extra chromosome leading to significant neural and physical defects, one of which is their 'similar' appearance as you term it.",
"Those with Down's appear to have a significant degree of deficiency in midfacial area, ... | [
"Intersting that the comparison to differentiating among Asians comes up - Dr. John Langdon Down, first English physician to describe the syndrome, named the disorder Mongolism as he thought these patients were simply expressing traits that made them more like ethnic Asians. When that theory was later proven incorr... | [
"Plenty of disorders have both neurocognitive effects and physical developmental effects. For example, ",
"Dubowitz syndrome",
" causes severe retardation as well as microcephaly (small hands and feet) and specific facial features.",
"Often one major mutation can cause more than one phenotypic effect. Traits ... |
[
"Why are coastlines crinkly near the poles but smooth in the tropics?"
] | [
false
] | I've noticed from playing that you can instantly tell how close an island is to the poles by how crinkly its coastline is. Everything in the Arctic or Antarctic has intricate crinkly edges: Svalbard, Ellesmere, the Falklands, the Kerguelen Islands. Tropical islands look totally different, smooth and rounded: Sri Lanka, Barbados, Nauru. Why's that? Edit: I'm getting notifications every few minutes about glaciers, erosion and Slartibartfast, and almost all of the comments vanish so no one but me can see them. But thank you for all of the answers, I am feeling thoroughly educated! | [
"Jagged coastlines near the poles are caused by glaciation cutting through the landmass and isostatic rebound.",
"Smooth coastlines in the tropics and as you near the equator are due to heavier weathering from rain and liquid water.",
"Ice cuts, water erodes.",
"This is just the simple explanation from what I... | [
"Because of the way that glaciers and waves shape the land.",
"In the polar regions, glaciers advance and retreat over thousands of years, carving out fjords and other features in the coastline. The glaciers erode the land, creating valleys, and deposit the rock and sediment they have picked up in the process, bu... | [
"There's also a lot of rounding and smoothing from biomass -- soil erosion depositing deltas, for example."
] |
[
"Do lower rates of photosynthesis necessarily mean lower rates of carbon intake in trees?"
] | [
false
] | Or more specifically, do trees use carbon dioxide as it comes in, or do they have a way to store it before actually using it in photosynthesis? | [
"Trees can't. Cacti can.",
"Plants need CO2 and get it by opening little valves called stomata on their leaves. This lets CO2 in but also lets water out.",
"If you are a cactus or a jade plant you open your stomata at night when water loss is slower and store CO2 as ",
"crasullacean acid",
". During the day... | [
"Might mention the existance of CAM photosynthesis as well. CAM plants also can store CO2 in form of organic compounds during the night and use it for PS during the day."
] | [
"Thanks for the answer! Thanks for the link as well -- that was quite helpful."
] |
[
"Does medicine really absorb into your system faster if placed under your tongue?"
] | [
false
] | I've heard this before as for with heart medication to place it under your tongue so it gets directly and more efficiently into your blood stream. If so then why and how does it work? Also wouldn't the same go for alcohol if you hold it under your tongue, it should get absorbed into your blood stream quicker? I know that you can get drunk by placing alcohol in your rectum for a similar reason. | [
"I've heard this before as for with heart medication",
"That is nitroglycerin. It is one of the few medications which is administered sublingually (under the tongue). Once absorbed, nitroglycerin is converted into nitric oxide (NO), which is a naturally-occurring vasodilator (expands blood vessels). It is abso... | [
"This does produce an erroneously high value. I believe people have actually tried this defense in court, but don't quote me on that.",
"When I was in middle school, we had an inventor of one of the breathalyzers come in. He had a student swish mouthwash and tested them right after. Their calculated BAC was ve... | [
"At least in Finland breathaliser results are not used in court. If you blow over the limit you get bloodtests."
] |
[
"Will the asteroid belt eventually become a planet?"
] | [
false
] | Figure that seems like a logical step in the formation of planets (a bunch of small pieces forming larger and larger chunks of matter), but then I'm wondering if there's some counteracting that the outer planets do that might keep them in a more uniform distribution. | [
"No. The current thinking is that the asteroid belt is matter that never formed a planet, but there is no mechanism that would cause it to merge into a single object. It's also worth noting that the entire asteroid belt has a mass equal to about only 4% of the mass of the Moon."
] | [
"Purple tags aside (although I might have to change my username to \"purple tag guy\"), ",
"here",
" is a source, which includes this:",
"The total mass of the Asteroid belt is estimated to be 3.0 to 3.6×10",
" kilograms, which is 4 percent of the Earth's Moon."
] | [
"Larger than Mars? Were do you get your info from? I don't know about initial masses of the ring that didn't coalesce due to the gravitational influence of Jupiter or whatever mechanism, but I cannot believe that the asteroid belt currently contains any magnitude of the mass of Mars in it. I would be absolutely ... |
[
"Are there any mammals or reptiles that evolved into the water and then back out again (or vice versa with amphibians)?"
] | [
false
] | More specific, is it possible for an animal to change phylum and then back or different one? | [
"This is one hypothesis for the origin of snakes-they came from marine ancestors. See: ",
"http://en.wikipedia.org/wiki/Snake#Origins",
"\nBut no one really knows for sure.",
"Also, changing phylum is something entirely different. Amphibians, mammals, fish, and reptiles are all in the same phylum. And you... | [
"I don't know of any examples where a terrestrial vertebrate evolved to be fully aquatic and then evolved to be terrestrial again. There is a hypothesis that this is true of humans (",
"http://en.wikipedia.org/wiki/Aquatic_ape_hypothesis",
") but most scientists consider it to be unlikely. In any case, if an an... | [
"The aquatic ape hypothesis is nearly universally considered nonsense, mind you."
] |
[
"What’s the largest star system in number of planets?"
] | [
false
] | Have we observed any system populated by large amount of planets and can we have an idea of these planets size and composition? | [
"There is some speculation that most/all star systems (after sufficient time) ",
"self-organize",
" themselves into systems of 7-10 planets. This would be accomplished through Harmonic-Resonance which would cause all matter in an accretion disk to get pushed/pulled into bands at specific intervals from the pare... | [
"There are several systems that are known to have at least 6 planets. TRAPPIST-1 has 7 known planets. Kepler-90 is reported to have 8. HD 10180 has been reported to have as many as 9, but all the exoplanet catalogs I've looked at (",
"NASA exoplanet archive",
", ",
"exoplanet.eu",
", and ",
"exoplanets.or... | [
"Probably not, it is just easier to find planets here than elsewhere."
] |
[
"Is an encrypted disk volume more susceptible to becoming completely unreadable if some of its bits are altered or lost?"
] | [
false
] | [deleted] | [
"Your answer will depend on what type of encryption algorithm you use and what kind of corruption you mean. For example, using AES encryption in ECB mode would be generally resistant to \"bit flipping\" data corruption, while CBC mode is less so.",
"With AES in ECB mode, the encryption procedure takes fixed-size ... | [
"It depends upon the implementation. Many encryption schemes also employ compression in one form or another, and many compression algorithms employ varied notions of integrity checks and recovery records (the latter of which is often configurable, to allow the user to increase the amount of data in the archive devo... | [
"One thing seems worth adding: Compressed disks generally have some sort of metadata that can be crucially important. For instance, Linux's dmcrypt has a special block where it keeps the actual key your data is encrypted with, and your passphrase then encrypts that key. This allows for multiple passwords that unloc... |
[
"Have humans evolved in the last two thousand years and if so how?"
] | [
false
] | null | [
"Humans are always evolving. However, 2,000 years is a very tiny length of time to be looking for evolutionary changes. You need to bump that up to at least 5,000, preferably more like 10,000 years to see significant evolutionary changes. "
] | [
"The disease response things mentioned would be the most recent evolutionary changes. Which makes sense if you think about it, the quickly evolving pathogenic microbes and viruses are the only persistent challenges to human fitness (across all human populations). I'll throw in a few of my favorite examples when I'm... | [
"that's not always true. humans are being tossed into a radically new environment which is a catalyst for rapid evolutionary change. ",
"for instance, the hippos closest cousin is the whale, which has evolved so rapidly upon becoming buoyant we required substantial genetic evidence to discover this. ",
"it is a... |
[
"[Astronomy]Why does space not have random visible light noise?"
] | [
false
] | If the universe has random noise and background radiation from the big bang, why is nobe of it in the visible spectrum? | [
"The temperature of the cosmic blackbody radiation that fills space is between 2 and 3 kelvins. As a result, the thermal photons are concentrated at wavelengths much longer than those of visible light. This temperature is so low because space has cooled off as it has expanded, and it has been expanding for a long... | [
"Also of interesting note is that the anisotropy of the CMBR - i.e. how much it varies from one location in the sky to another - is less than one part in 100,000, so even if it was visible it would look pretty damn uniform."
] | [
"Additionally at one time in the past this background radiation would have been in the optical, but as already said it has 'cooled' since to microwave wavelengths. Prior to this it would have had shorter than optical wavelengths."
] |
[
"What are the difficulties with algal Bio fuel, biodiesel specifically?"
] | [
false
] | null | [
"Very interesting...keep us updated on how it goes.",
"The main problem in industry is balancing cost and yield. If you dont control their environment (farming them in the ocean), then they spend all their energy fending off disease and the like, rather than producing lipids which can be turned into biodiesel. I... | [
"I looked into producing biodiesel some years back, the chemistry is pretty easy, so long as you have access to the right things. A few of them wont be readily available come the zombie apocalypse."
] | [
"I'm curious about how do you plan to do it. I can help you out (I make setups to carry out chemical reaction engineering all the time) with tweaking your design if you share.",
"Forgetting the actual process for a second, you need to figure out how you're gonna test the product. My labmates do this with a DSC to... |
[
"Could one say that our body is basically a biotechnic robot controlled by our brain?"
] | [
false
] | I started to think about it after watching | [
"This view overemphasizes brain states and neglects the contribution of body states, which are implicated in emotional responses that have been shown to be involved in human decision making. See \"the feeling of what happens\" by Antonio Damasio and research on embodied cognition, and affect. ",
"This also downpl... | [
"I should clarify and elaborate. You can get some background on ",
"embodied cognition from Wikipedia",
"George Lakoff's writing is often accessible: ",
"http://www.qwiki.com/q/#!/George_Lakoff",
"Lakoff, for example, talks about how metaphor plays a role in thought, and how important the body is in those ... | [
"As a student of neuroscience, I think that you are either misinformed or misconstruing the information you have. As far as my education has shown me, thought is an activity that happens solely between the neurons of the brain. ",
"Thought is profoundly effected by stimuli from the outside world. These stimuli ca... |
[
"Does freezing and thawing store-bought bread affect/retard mould growth?"
] | [
false
] | null | [
"First of all, most bread mold won't really hurt you. However it is obviously undesirable to eat. You can definitely keep it in the freezer to prevent mold from growing, if you don't mind the loss in quality of the bread. The fridge will slow down mold growth quite a bit, but in the fridge your bread will go stale ... | [
"Thanks you for your reply. ",
"Please let me clarify the question. If you freeze and then immediately defrost the bread, is that series of actions beneficial to bread shelf-life, all things being equal?",
"Thanks, ManofMystry"
] | [
"Gotcha. Good question. I really don't know for sure, but I'd guess probably not."
] |
[
"Why do flesh, tissue, muscle, bone, skin all heal on their own but Teeth don't?"
] | [
false
] | You break a bone and it will heal. Tear a Ligament or muscle, it will heal. Cut skin, it heals. Why do bad/cracked teeth not heal and go back to normal after a while? | [
"There are two cell types responsible for making teeth. The ameloblasts and the odontoblasts. The ameloblasts make the hard enamel that protect your teeth and the odontoblasts make the softer dentin that makes up the core of your tooth. ",
"Enamel is deposited on your tooth like frosting. Inside-> outside. This m... | [
"In addition, to answer the other ",
" (Why did we evolve like this?):",
"Because there hadn't been enough evolutionary drive to make proto-teeth develop in another way, and since then we're stuck at a local maximum in DNA-space. In non comp sci terms: As teeth are \"modified\" scales, they were \"intended\" (e... | [
"What?"
] |
[
"Some materials are better erasers than others, why do graphite particles stick better to some materials than others at a molecular level?"
] | [
false
] | null | [
"Not a certified scientist but how I understand it, graphite is comprised of covalent carbon bonds that exhibit mainly London intermolecular bonding with other substances. This means that it won't stick as well to more polar substances (i.e. glass, some plastics, etc.) while it bonds well with materials like drywal... | [
"I believe so. I'm really spitballing here but I think the eraser is more attracted to the simple carbon bonds of the graphite than the the lipid bonds of the lapsed. I'm assuming the paper chemical bonds are lipid soluble because it comes from tree bark which is an organic substance and cells have a lot of phospho... | [
"I believe so. I'm really spitballing here but I think the eraser is more attracted to the simple carbon bonds of the graphite than the the lipid bonds of the lapsed. I'm assuming the paper chemical bonds are lipid soluble because it comes from tree bark which is an organic substance and cells have a lot of phospho... |
[
"How are artificial flavors that mimic natural flavors made?"
] | [
false
] | Fruit flavored candy, BeanBoozled, ect. | [
"In some cases there is a very specific molecule that gives a majority of the characteristic to a natural flavor. If that happens to be true and if the molecule happens to be fairly simple then it can be manufactured in huge quantities for low costs using chemical industry. For example, limonene provides a citrus t... | [
"Even if the molecule is quite complex it can be mass-produced. This is most commonly done using modified yeast cells. And because it's are produced by living organisms, the product is considered 'natural' and not 'synthetic'. "
] | [
"Adding onto this:",
"Another factor in synthetic flavors (all flavors, really) is actually smell",
"(1)",
" and color",
"(2)",
".",
"One of the ways that Skittles saves in production costs is by changing the colors and smells of their skittles, but the actual flavor remaining the same.",
"I know that... |
[
"Why do birds, insects, squirrels, and other animals move in short, jerky motions?"
] | [
false
] | null | [
"It's a matter of size. It takes a lot more energy for a large animal to accelerate/decelerate a limb or such. On the scale of an insect, beating their wings is relatively easy. Here's the wikipedia article on the ",
"Square-Cube Law",
" in regard to biomechanics."
] | [
"Survival would be the main focus. They move short distances and check for any dangerous situations or predators. Hence you always see a bird when eating to pick to the food a few times, and then look around a few times, rinse and repeat."
] | [
"Fast movement allows the organism to be still more often, and movement attracts predators."
] |
[
"How are food calories scientifically measured, and how well does this reflect what is actually biologically available in living systems?"
] | [
false
] | What I have read suggests that basic values for caloric content are derived from bomb calorimeter studies, which seems to just represent how much heat energy can be given off by the substance through igniting it making careful measurements. Obviously this would not be a perfect surrogate for calories available to all living systems. For instance humans are unable to digest cellulose, so although it could give off energy on ignition, it would not be biologically available to humans. So how did we figure out calorie content for various complex foods and what its functional impact would be on human nutrition? | [
"This Link",
" might provide some usefull information. It states that the bomb calorimeter is an out-dated technique and not used anymore.",
"most of the calorie values in the USDA and industry food tables are based on an indirect calorie estimation made using the so-called Atwater system. In this system, calor... | [
"To expand, the values used are:",
"4 Cal/gram usable carbohydrate",
"4 Cal/gram protein",
"9 Cal/gram fat",
"7 Cal/gram alcohol",
"It's not exact, especially when it comes to the large variety of carbohydrates that exist, but it's good enough for government work."
] | [
"There's this device called a bomb calorimeter, which is a chamber pressurized with oxygen and filled with whatever you want to measure. ",
"You put this chamber in a very specific (well measured) amount of water, ignite it, then measure the change in the temperature of the water. ",
"From this, you are able to... |
[
"What will happen to the frequency and wavelength of the sound wave if we directly change the speed of sound? How will they change?"
] | [
false
] | null | [
"The sound wave will ",
"refract",
", similarly to how light would. The frequency stays the same and the wavelength changes."
] | [
"Is that what causes your voice to sound funny when you inhale helium?"
] | [
"This already happens with refraction. If a light wave enters another medium, the velocity of that photon will change according to the index of refraction.",
"When this happens, the wave length changesbut the frequency stays the same. V is proportional to wavelength, so when velocity increases, so does wavelength... |
[
"Could a railgun projectile reach low Earth orbit? The ISS?"
] | [
false
] | I understand that a railgun projectile could reach speeds of over 7000mph(high estimate) or 5000mph(low estimate). I was unable to find a range of the projectile or a definitive answer on the weight but one article from 2012 mentions it being around 40lbs. I know it would not be able to STAY in orbit however is there a possibility of the projectile reaching LEO and damaging satellites or even the ISS? | [
"No.",
"The speed that you mentioned is enough to reach the ",
" of the ISS and many satellites, even though not fast enough to remain in orbit. If your objective is just reaching it (based on your use of the word \"damage\" I guess crashing isn't a problem) this could be enough, if sent in a trajectory where t... | [
"In real life the projectile will burn up like a meteor",
"Just thought I'd add a visual for anyone interested. ",
"Here's some text footage",
"."
] | [
"For a roughly circular projectile, atmospheric drag is a huge problem. It's proportional to the square of the velocity if the velocity isn't very low. This gives you the differential equation v'=-kv²-g, which has the solution v=tan(atan(k v0/q)-tq)q/k and x=log(cos(qt)+sin(qt)v0 q/g)/k. where v is the velocity, x ... |
[
"How does exercise affect mood, and what is the best type of exercise for mental acuity?"
] | [
false
] | As a programmer, and before I had this profession; I noticed it was harder and harder for me to sit down and concentrate and work through a boring, but necessary task. I've also been, not necessarily a couch potato, but definitely not getting my recommended allowance of exercise. I had known, in theory, that exercise can help improve concentration. However, after starting running, I noticed I could work much more efficiently than usual; tasks that I couldn't bring myself to do before fell easily. I did some research (of the google variety) and it seems there is a general pop-sci consensus that exercising is affecting dopamine and endorphin levels; and this would probably account for my ability to concentrate. I read somewhere else that aerobic exercises were more associated with dopamine and endorphins than anaerobic exercises; so things like jogging would be better than weight lifting; for increasing dopamine production. In any case; it seemed to me that this is actually not really well understood at all (despite the pop-sci confidence). I am hoping someone with some expertise can give me a way to think about the exercise <-> concentration link, and maybe give some clarity as to what is really understood on the topic. At a high level, I am looking for a way to optimize my fitness routine around a sense of well being and being able to concentrate. | [
"OK. Here's what science can tell you to do wrt using exercise to improve executive function. ",
"30 minutes, hard aerobic exercise, 3X per week. This is what most studies use. It has a clear, unambiguous impact on executive function over a time period of months. You will become a more effective programmer. I rec... | [
"Thanks, I have been doing that.",
"What I have learned is that running is better than lifting; and also better than stationary biking of similar intensity. ",
"It also seems that longer is better (for ability to concentrate) but worse for recovery.",
"I'd like to know more though because I am sort of bounci... | [
"Thanks, I have been doing that.",
"What I have learned is that running is better than lifting; and also better than stationary biking of similar intensity. ",
"It also seems that longer is better (for ability to concentrate) but worse for recovery.",
"I'd like to know more though because I am sort of bounci... |
[
"How much propylene glycol would it take to kill you?"
] | [
false
] | I saw the news story on Fireball being pulled from European shelves due to a high amount of propylene glycol. Is there enough in it to kill someone? If not how much would someone have to drink before there were any harmful effects? | [
"an additional comparison would be to the ethanol in the beverage:",
"LD50/LC50:\nCAS# 64-17-5:\nDraize test, rabbit, eye: 500 mg Severe; Draize test, rabbit, eye: 500 mg/24H Mild; Draize test, rabbit, skin: 20 mg/24H Moderate; Inhalation, mouse: LC50 = 39 gm/m3/4H; Inhalation, rat: LC50 = 20000 ppm/10H;\nOral, m... | [
"A common way to measure the toxicity of a substance is the ",
"LD50 test",
". A population of laboratory animals receive the same dosage of the substance. The amount of killed animals is counted and the test is repeated with higher/lower dosages until half of the population is dead. The result is influenced by... | [
"Thanks!"
] |
[
"In movies, when a patient is about to pass out, a common cliche is the first responder saying \"stay with me\" or something to that effect, is there actually any medical benefit to trying to keep a person awake in such situations?"
] | [
false
] | The only context I know of where this is helpful is in surgeries where a patient is kept conscious and doctors want to make sure they haven't injured their brain. I don't see how this would help when a patient is losing blood and is entering hypovolemic shock (which is one of the most common context of this). Recently I saw this interview with where she recounts her experience with a ruptured brain aneurysm, she says she tried to keep as active as possible and started repeating lines from memory with the host stating that this is something that you should do in that situation. Is there any scientific basis to justify all this? | [
"It's really useful to be able to ask someone what's wrong. It's also helpful to be able to talk to someone to assess them. Keeping an injured person awake until they can be assessed is easier and probably less harmful than trying to wake a person with unknown injuries. "
] | [
"Doubtful, but keeping them as alert and oriented as possible (read: conscious) will help them maintain airway patency if nothing else."
] | [
"Yes, but is there evidence that talking with a patient slows down their loss of consciousness? if you are losing blood, for example, the rate at which you lose consciousness depends on the amount of blood lost. "
] |
[
"Why will cocoa powder only mix with warm/hot water but won't with cold water?"
] | [
false
] | So I noticed when mixing cocoa powder with water than when I pour cold water into the powder it really resist mixing up properly and it leaves a lot of cocoa powder dross on top even after lots of stirring. But when I pour warm/hot water it mixes up with little to know stirring. I suppose this is a food science question so I will tag it chemistry without that as an option. | [
"Warmer liquids in general have a greater ability to dissolve solids, and less ability to dissolve gasses in solution. ",
"A good way to remember this concept is by thinking of the energy in the liquid. A hot liquid, or gas, has lots of energy. All of the molecules are moving around quickly, and they all want mor... | [
"On top of the general answers already given, cocoa powder also contains some amount of fat. The fats will not easily dissolve in cold water, so cocoa is even more resistant to dissolving in cold water than many other substances."
] | [
"The whole dissolution thing is absolutely correct, ",
". With cocoa powder it's a lot more about the fact the small amount of oils and fats only melt at higher temperatures. If you put a stick of butter in cold water, it's... Not doing a lot. If you heat that water up, the butter can more easily melt. ",
"Plus... |
[
"How can two lasers combine to create white light?"
] | [
false
] | Two complementary colors, let's say red and cyan, can be combined to create white light. I also know that white light consists of all frequencies. How is it possible that all frequencies can be created from a superposition of just two single frequencies? If this is the case, this is very counter-intuitive. | [
"There is a tiny bit of confusion here: color is a psychological property, not a physical one. While it is the case that light composed of all wavelengths in the visible range is experienced as white, so is light made up of just the wavelengths we experience as red green and blue (that's how your monitors and tvs m... | [
"That's a good answer, Just one thing to add regarding the addition of wavelengths:",
"To see how different hues could be reached by combinations different wavelengths, one can use the ",
"color gamut",
". pure wavelengths are on the edge, combination of two wavelengths form a line between them, where the ra... | [
"Thanks for solid answers both of you, it helped my understanding a lot!"
] |
[
"Why don't waterfalls get worn down to gradual inclines?"
] | [
false
] | null | [
"Waterfalls form where a layer of hard rock lies on top of a layer of soft rock. The soft rock below erodes faster, creating a steep drop, sheltered by a ledge of hard rock above. Eventually, the soft rock starts to erode beneath the hard rock, creating an overhang, which breaks off when it gets too long, creating ... | [
"Thank you, that makes perfect sense."
] | [
"Yeah, more or less. They divert water into reservoirs at night, which is used to power the hydro plant during the day so the falls can be going at full-volume when tourists come by. At night, they're reduced to a trickle.",
"Also, one time the water was fully diverted away from the American falls.",
"For such ... |
[
"How do Virtual Machines handle Memory Caches?"
] | [
false
] | Let's say I have a multicore processor with three cache levels. On it, there is a hypervisor with two virtual machines running. As I understood it the hypervisor kind of to be a computer with smaller memory to each VM. I also know that a cache is a faster and smaller type of memory, like RAM relates to the harddrive, but a cache can't be explicitly targeted by an application programmer. Does an operating system programmer handle cache accesses? Or is the cache behavior determined by a even lower level, like directly in hardware? If the OS on one VM wants to write to the cache, does it tell the hypervisor "Hey I want to write to this specific line/address of my own virtual cache!"? A "virtual cache" sounds weird, because indirection is slow and caches are supposed to be fast. Also, when multiple VMs each have a dedicated space in the cache, these spaces would be rather small. Therefore, maybe the VM doesn't concern itself with caches and just tells the hypervisor on which vitual adresses it wants to read and write and lets the hypervisor decide when and where to access a cache. Probably I have misunderstood something about operating systems and it works differently altogether. The background to this question is that I'm reading the paper . They explain that the cache opens a side-channel, where information can leak from one process to another. They write that this also works for cross-VM attacks. I want to have a clearer understanding on how the caches of two VMs on the same host interact. I would be grateful for even some pointers. | [
"Caches are usually managed entirely in hardware, with no input from the software. This is true in both traditional (single-OS) systems as well as virtualized systems. There is only one set of caches for the entire system (though multi-core processors will usually have a separate L1 and L2 cache for each processor)... | [
"Thanks for the explanation! That’s the first high level detail that I was able to quickly grasp"
] | [
"I think an additional detail that would help is that most modern cpus have physically indexed caches. Meaning, they are caches of physical memory after virtual address translation. This means that the different VMs will compete for space in the cache but the CPU does not confuse them because they are using uniqu... |
[
"If the Earth was tidally locked to the Sun (like the Moon is to the Earth), would it still be able to sustain life?"
] | [
false
] | I'm curious to know what it would be like on Earth if we had no day-night cycle at all. Are scientists able to predict what the implications of that might be? | [
"If the Earth were tidally locked that would mean that one side the planet is perpetually in sunlight, and the other in darkness. This would result in continual heating of the one side from solar radiation, and cooling of the dark side from radiative loses to space. The atmosphere and ocean current may move some ... | [
"I can't recall the source, but I read in an article somewhere that not even the terminator would be habitable, because (and don't quote me on this): If the planet was tidally locked, solar winds unhindered by the Earths rotation would cause winds of up to 1000mph on the surface, effectively killing anything there.... | [
"The earth is protected from solar winds by the magnetic field, which isn't created by the earths rotation but rather the rotation of the earths core. So whether or not the solar winds would blow off the atmosphere, depends on whether or not the core of the earth stops spinning the same time as the earth does."
] |
[
"Why does blowing on a lit match cause it to go out?"
] | [
false
] | null | [
"Your intuition that it would burn brighter is good one, because fire needs oxygen to breathe. Fire also needs a fuel and a heat source. When you blow on a match (quite a small flame compared to bellows on a fire pit), which of those three things (oxygen, heat source, fuel) are you taking away?"
] | [
"Your intuition is correct. You get flames when you have flammable vapors in the air, and they get a source of ignition. I thought it was really interesting when I learned how candles work: the wick of a candle \"sucks\" up wax from the body of the candle by capillary action, and once in the wick, the wax vaporizes... | [
"You can also blow out a fire pit with a bellows and make the coals hotter in doing so. They ignite when you stop blowing. In this case you've got constant fuel, more heat and more oxygen but no fire.",
"What's fire made out of? I think maybe the bellows blow away the stuff that the fire's made out of."
] |
[
"Why did biological creatures evolve to be symmetrical?"
] | [
false
] | I understand the biological process that leads to symmetry to a certain extent.. But why did this happen? What's the evolutionary advantage? Is the coincidence due to universal forces and constraints? | [
"Bilateral symmetry has evolved many times. Within the echinoderms, which are generally considered pentamerally symmetric, bilateral symmetry has subsequently evolved in at least two groups, the irregular echinoids (sand dollars) and the holothurians (sea cucumbers).",
"Both those groups - as well as most bilater... | [
"If they weren't macro symmetrical they would find it harder to move in a straight line, also senses such as hearing and sight would be skewed making it harder to avoid attack and also harder to pinpoint prey."
] | [
"I think the symmetry is directly linked to the way that creatures move (or do not move) and the medium they are in. Let's look at the three dimensions for a creature on land. Up and down are significantly different due to gravity (parts of the creature are usually in contact with the ground, while others are not... |
[
"How do poisonous/harmful gases dissipate into the atmosphere?"
] | [
false
] | After seeing some news regarding chemical weapons recently I've begun to wonder/worry how exactly poisonous gases become non-lethal. I understand lethality is often a matter of how concentrated the gas is. But does that theoretically mean enough gas can be released into the atmosphere to make it entirely harmful? Or are there other processes which break down the gas into its components and render it harmless? | [
"As someone who has sat through a lot of atmospheric chemistry colloquia, let me add that ",
"hydroxyl radicals",
" are (one of?) the major degradation pathways for organic molecules in the Earth's atmosphere (so there's at least some radical chemistry that doesn't ",
" involve UV reactions)."
] | [
"You could never poison the whole atmosphere, even if you tried.",
"The most potent lethal substance known to man is the Botulinum toxin, with a median lethal dose via inhalation of ",
"3 ng/kg",
", or 186 ng for the average human (about the weight of a large pollen grain). The average human breathes about ",... | [
"wazoheat covered dilution pretty well. But as for the processes, there's (broadly speaking) two ways things can go; photodegradation and biodegradation. Gases in the atmosphere can/will be picked up by living things (or dissolve into rain and get into the ground that way, in order to be picked up) and then convert... |
[
"What is dark matter? (More questions inside)"
] | [
false
] | Do we even know what it is? If not, where does it come from? Who "found" it? Also, how is it created? Thanks | [
"DarthBarthus is correct; dark in this case means two things. 1) we don't know what it is... it's mysterious, and 2) it does not emit (or absorb) light. ",
"We don't know yet what it's made of. There are a number of plausible ideas out there, and lots of experiments working on figuring it out. As far as we ca... | [
"The existence of dark matter was first inferred by ",
"Jan Oort",
" and ",
"Fritz Zwicky",
". Dark matter was first identified by looking at how the stars in a galaxy rotated around the center of their galaxy. If the only matter present were the stars we can see, we should see stars further from the cent... | [
"Thanks, long and detailed answer!"
] |
[
"Could weapons grade uranium melt into some geometry that could explode?"
] | [
false
] | Basically does 95%+ U-235 need to be compressed by an explosion or theoretically could a cube say 50m per side explode? I guess my question is does the metallic lattice of the uranium need to be compressed further. If it does need to be compressed what depth of water would a cube need to be under for it to go super-critical? Follow-up are there any rarer fissionable elements that could do this? | [
"The critical mass of U-235 is about ",
"50 kg",
" for a sphere in empty space. The radius of this sphere is less than 10 cm. Anything larger will \"explode\". ",
"I put \"explode\" in quotes, because the U will begin to explode but, because it will no longer be critical, the explosion will fizzle. A nucl... | [
"U-235 on its own will not just explode. Assume you have more than a critical mass just sitting there. Don't ask how you got it to that condition, but assume you have 1.5 critical masses just sitting there. A fission chain reaction would begin and would rapidly increase in power. It would heat up rapidly and ev... | [
"Ah OK. So basically you'd need some external pressure greater than the internal pressure the uranium sphere generates. Otherwise it will be a splat rather than a boom."
] |
[
"What biological differences in some mammals allow for advanced movement very soon after birth?"
] | [
false
] | [deleted] | [
"That's awfully anthropomorphic. A lot of mammals give birth to babies that are highly non-independent, this has nothing to do with being human. Horses are the special ones here.",
"But you're right one one thing; there is a fundamental evolutionary trade-off between the impact of pregnancy on the mother and the ... | [
"We have a longer development time after birth because evolutionarily we can afford to. It was sort of a biological arms race to see how small a child woman could have so that she could increase the physiology, pelvis and whatnot, to be able to walk upright. As those creatures increased their social cohesion, child... | [
"Simply put, the biological difference is genetic. Mammalian embryos start out seeming quite similar and gradually differentiate as they develop due to genetic traits. For some mammals, like dolphines, the need to be carried along by their parent(s) is outweighed by the benefit and convenience of being independen... |
[
"How do we know that the sedimentary rock on Mars was formed by water, and not wind?"
] | [
false
] | This article (and others) are claiming that the sedimentary rock was created by water, but how do we know it wasn't from wind blowing sand into a desert, then the climate changing, and the desert moving. By desert in this case I just mean sand dunes, not just lack of water. | [
"In general, the process that transports sediment leads to characteristic differences between various aspects of deposits of sediments including the shape of grains, the distribution of sizes of grains, and the size and type of ",
"bedforms",
" within the deposit. For Mars, certainly eolian (wind blown) deposit... | [
"If I understand your question, I believe the answer is that the sand or dry dirt needs some other mechanism to help hold together the grains. If you think of the Sahara desert, you can picture all of the dunes. These dunes are representative of the structural limits of loose dry particles.",
"No matter how much ... | [
"Not exactly, I was thinking of the rock itself. The balls (concretions) are formed by precipitating minerals in the sedimentary rocks, before it becomes solid rock. But I guess for the minerals to precipitate in a significant amount, there would have to be water present, even if it was just a little bit of ground ... |
[
"Would an atomic bomb produce two mushroom clouds in opposite directions if the bomb was released in the sky?"
] | [
false
] | [deleted] | [
"When an atomic bomb goes off, it creates (in the remnants of the fireball, which becomes the \"head\" of the mushroom cloud) something like a bubble of very hot, low-density gas. At most altitudes it is going to be much less dense than the atmosphere around it. So like a bubble released at the bottom of a jug of w... | [
"It's spherical, but with weird fringes as it comes apart and isn't being held together the way it would be in an atmosphere. There are photographs of this, as the US and USSR both tested nuclear weapons in outer space in the late 1950s and early 1960s: ",
"Starfish Prime cloud, 1962",
". This was an exoatmosph... | [
"When a nuclear bomb goes off, the amount of material involved is initially very small - after all it has to fit inside a warhead! ",
"The explosion produces a tremendous amount of energy in the form of radiation at many wavelengths. So the first thing we see when any bomb goes off (anywhere) is the intense whit... |
[
"With the increase in population and decrease in trees, would we see a noticeable increase in CO2 in our life time?"
] | [
false
] | null | [
"We are already experiencing some of the most high levels of co2 the world has seen in recent history. This is due to burning of fossil fuels etc. ",
"Respiration in one human releases 900 grams of CO2 according to Wikipedia. So :",
"0.9 * 365.25 = 328.725 kg per year per person.",
"The united states census b... | [
"What do you mean noticeable? We notice it enough to get warming. Do you mean enough to affect our respiration?"
] | [
"Wow it means we lose a pound sleeping every night just by breathing "
] |
[
"Is a bar of soap always clean?"
] | [
false
] | Do bars of soap actively fight germs and bacteria even when they're not being "used" or do they simply collect the bad stuff? Or does the bad stuff get washed off with the top layer of soap and go down the drain, hence why soap bars get smaller over time? | [
"Actually soap in of itself is not clean, nor is it necessarily anti-bacterial. In fact, it is the mechanical action that is largely responsible for removing the little creatures living on you, not necessarily directly killing them either.",
"Soap's active ingredient is usually Lauryl Sulfate which is an amphipat... | [
"That was a great answer - like one you might expect from Bill Nye. "
] | [
"A luffa or a washcloth will probably increase the amount of stuff you wash off. However, the goal of washing is not to end up 100% sterile, that's impossible and ultimately detrimental - the vast majority of microorganisms that colonize your body are benign or even helpful.",
"Using antibacterial soap in the sho... |
[
"Why does salt/lime dissolve in water and why is the amount dependent on the temperature?"
] | [
false
] | So let me begin by telling from which direction I'm coming from. After using my water boiler in the kitchen for a couple of days, lime will settle at the bottom of it. Why does this happen? As far as I know warm water is capable of holding more salts and lime then cold water. Is this right? And my question then is, why is that even the case, why is there a difference in the amount of slat/lime, water can hold with different temperatures. I was wondering that because I don't understand why the lime settles down if it more it can dissolve in warm water. Is it only because of the steam that can't hold the lime? But then, why does there is no lime at the top of my boiler but only at the bottom? | [
"The reason lime deposits mainly at the bottom is that the heating element is where the highest temperature is found, and where water actually boils by direct contact with this surface. The rest of the body of water heats up by conduction/convection and, when boiling, by the bubbles of vapor flowing up the water.",... | [
"This is a really good answer. Thanks for the great explanation. Do you by any chance know where I can find a table of the solubility of salts in Water?"
] | [
"table of the solubility of salts in Water?",
"Most common salts should be in here : ",
"https://en.wikipedia.org/wiki/Solubility_table",
"For a more scientific approach, or mixtures of various salts (common ion effect!), best look into solubility product constants. Tables for common salts in water at 25°C ar... |
[
"If an air conditioner was locked in a (somehow) heat-sealed room, with it's air intake, would the room (not the internals of the aircon) get hotter or colder or stay the same?"
] | [
false
] | null | [
"Warmer. Even if the transfer of thermal energy from its intake to its outtake can be considered equal, the fact that it has to use energy to run will result in a net growth in temperature.",
"This is similar to the question of: \"If a refrigerator is thermally isolated in a sealed room, then would that room warm... | [
"The room would get hotter. Think of it this way: to pump out colder air, you need to create at least as much hotter air (to obey the laws of thermodynamics). So that alone balances out. However, on top of that there's also a motor running to achieve this process, so you get additional heat from that."
] | [
"Cool, thanks :D"
] |
[
"Basic heat exchange question"
] | [
false
] | null | [
"You can have liquid water at 100 C."
] | [
"You are correct, with no temperature difference there will be no heat flow. If there were it would be a violation of the second law of thermodynamics."
] | [
"The phenomenon is ",
"vapor-liquid equilibrium",
". There is a different phenomenon known as a ",
"superheated liquid",
" where a liquid remains a liquid well above its boiling point until it is disturbed, but that isn't really related to the question at hand."
] |
[
"Say the Continental US is a flat object and population density determines its actual density. Where would it's Center of Gravity be?"
] | [
false
] | For instance, if you were to balance it on top of a pole, where would you put the pole, somewhere in the midwest? But where specifically? | [
"For the whole of the US, this location would be near Plato, Missouri.",
"The US Census Bureau has an animation of how the mean center of population has moved from 1790 to 2010 ",
"here",
".",
"There's also a news story ",
"here",
"; excerpt:",
"The Census Bureau calculates the center of population af... | [
"Did this compensate for alaska and Hawaii? Since they are detached it would skew the results westward."
] | [
"It does include Alaska and Hawaii.",
"The Wikipedia article on this subject ",
"states",
":",
"The addition of Alaska and Hawaii to the union moved the center about two miles (3 km) farther south and about ten miles (16 km) farther west in 1960.",
"The citation for this statement isn't there any more, bu... |
[
"If someone or something could move faster than the speed of light, what would happen to its shadow?"
] | [
false
] | null | [
"That’s fair. Just was disappointed. Have a good day."
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"guidelines",
"Please see our ",
"list of related subreddits",
" for other options for your question.",
"If you disagree with this decision, please send a ",
"message to the moderators."
] | [
"Lame."
] |
[
"What exactly is a “panoramic view” in astronomy maps and images?"
] | [
false
] | For example, I understand a panorama when taken from my phone. I understand that, if it is a 360 panorama, the sides will wrap around. However, astronomy maps and images (e.g. the cosmic microwave background images) are ellipsoidal. Does this imply the image wraps around at all the edges? Why is it ellipsoidal instead of circular? Are we looking at a pre-specified projection? Is there an article where I can learn more about the history of them? I really have not been able to find an answer on google. Panoramic space images or maps link to many beautiful photos, but not to the answer I’m looking for. Thank you in advance, not easy to put this question into words! | [
"Looking at a map of the whole sky is similar to looking at a map of the earth, like the ",
"Mollweide projection ",
". A sphere is 360° around its equator but only 180° from top to bottom, which is why the projection isn’t circular. Because of the rotation of the earth it’s easy to pick a top and bottom, but i... | [
"Thank you! This is what I was looking for."
] | [
"This is the ",
"Mollweide projection",
", and is easiest to understand by looking at a Mollweide map of Earth. It is ellipsoidal because it is a projection of the surface of a sphere onto a 2d map while keeping area correct and without too much distortion."
] |
[
"What’s the mechanism that causes sore throats due to viral infections?"
] | [
false
] | I cannot find anything about this online. I know that viral infections, and to a lesser extent, bacterial infections, cause sore throats. But WHY? Is it beneficial to the body in fighting infections somehow? Is it inflammation of the lymph nodes? Can’t figure it out! | [
"Many viruses/bacteria first encounter our nose/throats/upper airway when we inhale them from other infected people. The probable combination between the upper airway being the first tissue inhaled pathogens encounter and an evolutionary adaptation towards that specific type of tissue means the upper airway is wher... | [
"<recruit more immune cells",
"Some of these immune cells are literally like bouncers shoving through a packed crowd. The push between cells that normally do not have any space between them, and in their wake extra plasma may flow in. ",
"Imagine a packed club, and then 50 or 100 huge bouncers show up and begi... | [
"https://www.wikidoc.org/index.php/Pharyngitis_pathophysiology",
"Essentially viruses can directly invade the cells, bacteria can release toxins and things that irritate nerves, all of this can cause immune cells to come and cause inflammation, and your mucous can also be irritating."
] |
[
"Orbital Trajectories and Error?"
] | [
false
] | I first appreciated what a free return trajectory was when I watched where a science teacher uses a lycra sheet and weights to demonstrate gravity (free return is at the 6:20 mark). The trajectory makes sense to me and I guess you could say you "fall" all the way to the moon and fall all the way home again. What I don't understand is that ideally the whole path is predetermined by the velocity of the object when it leaves the earth. How is this done so accurately? I know that mid course corrections are possible but I assume they must be minimal. Maybe a better question is how accurate does the initial velocity need to be? That is an earth/moon question from the Apollo era. I had the same sense of "how do they achieve that accuracy" this year when New Horizons not only reached Pluto but passed between Pluto and Charon.......wow | [
"It's simple: they don't have the needed accuracy at launch (for some trips you might need to be unpractically precise). You might know that in general, the error in the configuration of a mechanical system grows exponentially, so no matter how good you are, you often aren't able to calibrate everything in advance.... | [
"When shooting for the moon, you can normally get within 2-3km/s and still be very close to the trajectory you were aiming for. ",
"The change in velocity required to go from low earth orbit to the moon is 3 km/s, according to Wikipedia. Your numbers aren't entirely correct."
] | [
"When shooting for the moon, you can normally get within 2-3km/s and still be very close to the trajectory you were aiming for. ",
"The change in velocity required to go from low earth orbit to the moon is 3 km/s, according to Wikipedia. Your numbers aren't entirely correct."
] |
[
"Can someone become un-allergic to something?"
] | [
false
] | [deleted] | [
"Sure, the process is called ",
". It can happen naturally, after extended exposure to an allergen (this can also aggravate symptoms), or therapeutically, through ",
"immunotherapy",
" (where patients receive repeatedly, and over a long period of time, small doses of modified allergen)."
] | [
"Thanks much, this is the type of response I was hoping for"
] | [
"I was allergic to nuts (and a bunch of other stuff) for ~7 years, but now i can eat nuts again except cashews."
] |
[
"If I see a fly land on my food, should I ignore it and go ahead and eat the food?"
] | [
false
] | When a fly lands on my food I always feel kind of revolted and I wave it away, but I don't know if I am being hyper-fussy by not eating that bit, or being sensible because I could get ill. I suspect I'm being fussy. But then, why do we go to such lengths to keep food fresh and covered up if there's no risk? So how much risk is there of the fly passing on some kind of bacterium that might do me harm? | [
"Your immune system is pretty beastly. Keep in mind the environment in which the human body was conditioned for included ravaging diseases and general filth. Our immune system has adapted to combat common environmental microbes and pathogens through built up passive immunity. Unless the fly transmits something s... | [
"You might not like this answer... You likely consume many flies during an average year without harm.",
"\"it is not possible to eliminate pest insects from the human food chain. Insects are present in many foods, especially grains. Food laws in many countries do not prohibit insect parts in food, but rather, th... | [
"Yes, it's true. They eat by regurgitating enzymes onto their food, letting the food dissolve into a soupy mess, and then sopping it all up with their sponge-like mouthparts."
] |
[
"At a small enough scale, visible light wouldn't register as such since you'd be smaller than the wavelength. Are there types of energy too large for us to experience in a similar manner?"
] | [
false
] | I've read that we can't see objects that are smaller than the size of the wavelength range of visible light. I hope I'm getting that right? Are there types of energy with wavelengths that are so large that we cannot register them? | [
"Not really. Radio waves are the longest type of electromagnetic radiation. They range from centimeters to kilometers and larger in wavelength. Despite their large wavelengths, we stull use them all the time. As long as you have an antenna long enough to emit or receive these long waves, you can still use them. ",
... | [
"Random fun information: Very long wavelength radio waves are used as an extremely low-bandwidth way to communicate with submarines:\n",
"http://en.wikipedia.org/wiki/Extremely_low_frequency",
"This requires an antenna that is thousands of kilometers long, for which purpose the earth itself is used."
] | [
"This is not entirely correct. An ionized plasma will not transmit waves with a frequency higher than its \"plasma frequency\", which for the Earth's ionosphere is about 10 MHz - in the middle of the radio/TV spectrum."
] |
[
"[META] - AskScience Journal Club!"
] | [
false
] | Hello AskScience! Today we're rolling out the AskScience Journal Club as a new trial feature. Basically, this thread will be a dedicated space for discussion of interesting research studies in a variety of fields. This presents an opportunity for our panelists to talk about interesting topics that may not be asked about very frequently, as well as a chance to demonstrate how scientists read and critique journal articles. Meanwhile, our readers get exposure to both the cutting edge of research as well as some of the lesser-known aspects of science. This initial post can range from a simple "here's this cool article on the topic of X, which basically found that Y, which is important because Z", to something more elaborate that be included in a . AskScience users are encouraged to engage in a dialogue about these studies: don't understand a paper's methods? Disagree with the overall significance? Want more info on the background context of this study? All are great questions to ask the panelists! We also welcome discussion between people other than the OPs for each paper - while the panelist who originally posted the paper likely has expertise and interest in the area, I'm sure that none of them will claim to be the final authority on any topic. Many similar "I read this article in the NYT about a research study, can someone tell me more?" questions are posted to AskScience, and we absolutely want to discuss topics that are of interest to you as well. Because these topics involve providing analysis on published literature we understand that not everything can be sourced, but as always try to keep everything as factual as possible and make it clear when you are offering your opinion vs established facts. Please feel free to message the mods with any feedback or suggestions you may have, but let's keep those comments out of this thread to avoid clutter. If this experience is well-received we may continue this as a regular (weekly?) series, so let us know what you think! Lastly, a big thank you to everyone taking the time to discuss papers! Our success is largely dependent on our user base and our panelists, so keep up the good work, both with asking and answering science questions! | [
"I'm a biophysical chemist, and so I've chosen a very recent (presently in press) paper that touches upon protein-membrane interactions, membrane biophysics, and some interesting (NMR) spectroscopy. All of this is right up my alley, so I was actually interested enough to do more than just skim through the figures... | [
"I thought it'd be interesting to talk about the paper ",
"Use of azithromycin and death from cardiovascular causes",
" by Svanstrom et al, published in the New England Journal of Medicine (one of the larger journals in the field) this past May. ",
"To provide some background, ",
"azithromycin",
" is a t... | [
"1) Speaking as someone with zero experience in SLF or DROSS (in the spirit of keeping initialisms and acronyms to a minimal, they stand for \"separated local field\" and \"dipolar recoupling on-axis with scaling and shape preservation\"... yeah...), could you explain what those techniques are and how the residual ... |
[
"Explain electron spin, how .5 spin gives objects mass, and why bosons have a spin of 1."
] | [
false
] | null | [
"Particle spin is an intrinsic amount of angular momentum that they have, i.e. something that is the same no matter what angle you look at it. Multiplied by Planck's constant, bosons have spins of 0,1,2,3 etc and fermions have spins of 1/2, 3/2, 5/2 etc. I'm not sure what you mean about mass."
] | [
"Actually, just about all of this you can read about on Wikipedia ...",
"You're right, let's close this subreddit and leave a redirect to Wikipedia in its place."
] | [
"To expand on this, Fermions obey the ",
"Pauli exclusion principle",
". This means that two identical fermions can't occupy the same quantum state at the same time (roughly, they can't be in the same place with the same energy at the same time). This is what gives matter (composed of fermions like protons, neu... |
[
"When humans imagine an image in their brain, is the image we see being activated from the occipital lobe or somewhere else?"
] | [
false
] | [deleted] | [
"When we imagine movement, such as a batter hitting a baseball, our mirror neurons fire. This event resembles the activity that the motor neurons would exhibit we were to perform the action of hitting a baseball, however we will not move at all. It is hypothesized that this is one reason, among many, why humans e... | [
"Just to clarify, mirror neurons would fire duirng both doing and seeing. Also, I think the question relates more to thinking about the sight of someone hitting a baseball compared to actually seeing it.",
"The occipital lobe is related to dreams and damage can cause them to cease, so it could be connected to con... | [
"Some of us do not have any visual images in our minds. Some of us think entirely in audio. This is worth consideration, perhaps."
] |
[
"Does milk really help you grow taller?"
] | [
false
] | My parents always used to say that drinking milk makes you taller. Is there any truth to this? | [
"A more accurate statement would be that drinking milk enhances your ability to grow taller. It doesn't necessarily make you taller. It's like saying eating protein makes you grow muscles. It can help you grow, but it doesn't do so automatically. It's only one part of a complex equation."
] | [
"While your still very young, calcium is absolutely necessary to help strengthen bones and lack of calcium could indeed stunt growth and have negative effects. But this is only during the weening time period. After that it has not real benefit when it comes to bones"
] | [
"Yes, but there is more to it than drinking milk. Overall nutrition during early development has a significant impact on height. Milk contains important nutrients, including fats, sugars, and proteins, as well as the calcium that is often focused on. Milk alone isn't sufficient for healthy developement, but the pro... |
[
"Is it possible to put out fire with Gasoline?"
] | [
false
] | [deleted] | [
"I'm sure someone will correct me if I'm wrong, but here it goes.",
"Gasoline burns as a vapor, but not very well as a liquid. So you could extinguish a flame if enough liquid Gas engulfed the flame so as to smother it out. Obvious risk that if it did not go out, it would be flooded with an accelerant."
] | [
"I think the problem would be delivering the gasoline to the fire in a manner that would prevent it from separating or becoming and aerosol. As you said, the liquid isn't the problem, the vapor is. You can't simply spray it or pour it over the fire fast enough unless you could evacuate all the oxygen first. "
] | [
"One way of extinguishing fires is with explosives - see videos of putting out burning wells in the Kuwaiti oil fires and other well blowouts. One firefighter started a company around this premise - Red Adair was known for putting out huge oil fires with explosives.",
"The premise is that if you have a large fire... |
[
"Why do some helicopters have 2 blades whilst others have 4 or 5?"
] | [
false
] | null | [
"The greater number of blades in a helicopter enables it to produce more lift, hence heavier helicopters, such as Sikorsky CH-53 has more blades. ",
"However, there will be trade offs from having more blades. The helicopter blades produce a wake of turbulence behind them, reducing the efficiency of the subsequent... | [
"No. Counterbalancing (counterweighting you called it) a single blade would give a balanced rotation, but would require the same energy (fuel) to spin, while only creating half the lift, as you would only have one lifting blade. This single lifting blade also causes an issue where it is being lifted up, and prying ... | [
"Your correct, thats exactly what would happen. But more blades means you need bigger engines to turn them. This increases fuel consumption, which means you would need to have bigger fuel tanks and cary more fuel. ",
"It all depends on the purpose of the chopper. If you want to fly faster or lift more weight then... |
[
"What is it that makes chemotherapy successful with some people but not others? (x-post from askreddit)"
] | [
false
] | This has probably been asked before, but my 2 minutes of pre-question research turned up nothing. I'm curious why chemo is successful with some cancer patients but seems to have little or no effect on others. What determines the effectiveness? If it's body chemistry, wouldn't doctors be able to determine whether or not it will work prior to beginning treatment? I lost my dad to esophageal cancer in '06 and watched him suffer through chemo for 2 months before he died. I'm wondering why he was subjected to the hell of this form of treatment when, in the end, it didn't improve his situation. | [
"First of all, I am sorry about your father. Cancer treatment is extremely complex and can cause horrible side effects to those receiving chemotherapy. I will try to explain my understanding of it.",
"There are many, many differences in the different types of cancer that occur in the human body. This includes dif... | [
"Wow, fascinating! Thank you for your thorough explanation."
] | [
"no problem. Let me know if you have any other questions!"
] |
[
"Why is T wave on ECG (in most leads) of same polarity like QRS complex, despite having the opposite vector?"
] | [
false
] | The only explanation I could think of is that although the electrical axis of repolarization is of opposite direction than depolarization, the flow of ions through the membranes is opposite as well (positive ions go inside the cell during depolarization and outside during repolarization). So it's like double negative. Is that right? And, if it is, can you please specify the exact mechanism of how does this flow affect the ECG? I just feel it could be right, but can't support it with any logic. | [
"The last cardiomyocyte to depolarize is the first to repolarize. So it means that the endocardium is the last portion of ventricle thickness to depolarize, but it will be first portion to repolarize.\nThink of repolariation as being the opposite of depolarization. Whereas a positive deflection will be seen as a de... | [
"Yeah I think understand this. The order in which the ventricle wall layers depolarize and the direction in which this action advances determine the mean vector of repolarization. At the same time this vector is approximately opposite to the one of repolarization. But still, my question is, ",
" will a repolariz... | [
"Sorry that I'm a little unclear, I should probably have waited with answering this until I sober up tomorrow morning.",
"Repolarization begins in the epicardium and base, and spreads towards the endocardium, whereas depolarization does the reverse. As a result, the same polarity develops transiently across the h... |
[
"how much energy would we save if we stopped lighting up streets, houses, and parking lots, and focused on cheap individual night vision?"
] | [
false
] | I hate light pollution and the energy used has to be a huge amount, but is it even feasible to get good enough night vision cheaply? Sorry kind of turned into a 2 part discussion... | [
"Hey, turns out that I work with night vision devices for a living. Couple things.",
"1) Yes, right now, the technology is pretty expensive. Military grade stuff is very expensive. To provide a pair of night vision goggles to all the 300+million (and growing) people in the country would be a monumental underta... | [
"At an approximate population of 300 mil. I'd say the USA."
] | [
"Night vision",
" is pretty crappy compared to illumination. You can't see colours or details for a start, so any task that required those would be impossible. And you're reliant on the goggles, so if you run out of batteries, or they get damaged then you can't see. Or if you just can't afford them. Luckily our s... |
[
"What is the correct term for when the effects of an isolated variable cannot be accurately identified in the context of a large robust study? Esp. in relation to nutrition science."
] | [
false
] | Sorry for messy title but I'm not exactly sure how to ask this. ------------ Compound madeup123 has been shown to raise blood pressure. This has been shown in short-term, clinical experiments, by administering the compound to test subjects, and taking measurements. It turns out that the goofball fruit, which we have all been enjoying for years, has been shown to have relatively high levels of madeup123. Dr. Jon Smith, in his latest diet book, puts the goofball fruit on his list of foods to avoid, citing the experiments with compound madeup123, connecting it to increased risk of heart attack, stroke, and damaged arteries. ----------- I have a friend who seems to switch to a different diet every few years. Inevitably he has some book to show me, which "proves" that this diet is the best one. Sometimes its written by a medical professional, sometimes not. Littered throughout the book are examples like what I have written above. But here is the crux of my question: I understand this is different than trying to look at a large database of outcomes, and trying to draw some general conclusions. E.g. - a study of 300k coffee drinkers shows that drinking a cup a day extends your life by a few years. Ok, I'm skeptical of some of these, but I get it. This is different than the example I've given. But these fad diet books are rife with the kind of thing I'm talking about and sometimes it drives me bonkers. Either something wonky is going on here or I'm just not understanding something. If its the latter than thats fine with me, please educate me. What is the technical term for this sort of thing - statistical significance, or noise....or something else? What am I missing? | [
"First of it is important to make one thing very very clear. Nutritional science is despite its name not a an exact science. A lot in the field can not be proven due to the very problem you describe. It is almost impossible to downright impossible to without major concessions to get any result that is above error r... | [
"thought at first maybe you were thinking of \"confounding variable\" but maybe youre looking for this:",
"\"In an experiment, an extraneous variable is any variable that you're not investigating that can potentially affect the outcomes of your research study. If left uncontrolled, extraneous variables can lead t... | [
"Yeah I'm not sure what the right words are, so I figured the best thing I could do was provide a hypothetical example.",
"Thank you for the detailed answer, very helpful."
] |
[
"Would it ever be possible to clone or create extinct animals out of fossil DNA?"
] | [
false
] | If so, why should or shouldn't we? | [
"There's interest in it, and there's been at least one ",
"partially-successful attempt",
". There's constant publicity about teams who claim they're going to clone mammoths, but group after group has been announcing that for decades and at this point the default assumption is that they're all full of shit. Eve... | [
"It takes 521 years for half of your DNA to decay",
". ",
"If you run the numbers:",
"...And so on.",
"Tyrannosaurus lived around 68-66 million years (My) ago. If we take 67 My, the number in-between, and divide it by 521, we get (rounded up) ~130 000 iterations of this decay process. As you can notice, the... | [
"Yes and no. ",
"In theory you could potentially create, what looks and appears like, an extinct animal but one of the big problems is knowing what is important and what isn't. The most straight forward way of creating this mutant animal would be to use a construct, probably an animal, that shares a relatively re... |
[
"How do peripheral neurons receive oxygen?"
] | [
false
] | [deleted] | [
"The same way all your peripheral cells get oxygen.",
"The arteries from the heart divide and shrink as they progress from the aorta. From these, capillary beds spring, which are a maze of small vessels slightly smaller than an RBC. Across the walls of capillaries oxygen/CO2/nutrient exchange occurs, and these th... | [
"So, do we see a decrease in neuronal conductivity when blood vessels are constricted? For example, will someone with hypertension have a weakened nervous system?"
] | [
"When neurons do not receive enough oxygen they will quickly reduce their energy production and ion channel conductance. The latter will cause the neuron to have a higher excitation threshold which will lower the overall activity of the neuron. So yes, when there is not enough oxygen available to the neuronal popul... |
[
"Why do strokes only happen in the brain?"
] | [
false
] | null | [
"That's the definition... Interruption of blood supply to other parts of the body has other names like \"heart attack\""
] | [
"I was thinking about the specific cause, like a blood clot. Why don't those clots cause disaster elsewhere, like a finger or something?"
] | [
"Ah, I recommend making a new post with that rephrased question then."
] |
[
"Would decompression have any affect on stopping or slowing a projectile in space?"
] | [
false
] | What prompted this question is the scene in Star Trek Into Darkness where Khan and Kirk perform a space jump first by being depressurized and pushed into the vacuum of space, and then guiding themselves to an entry port on the enemy ship... that also depressurizes when it opens. Wouldn't this exert the same or similar amount of force? If yes, would that not stop them instantly at the point of entry? Would that sudden halt kill them, or does decompression disperse air quickly enough that any incoming projectile (human or otherwise) has more than enough mass to pass right through? Are aerodynamics even at play in space? Hope that makes sense. I'm sure there are variations depending on the size of the projectile and amount of pressure on either end, but I was curious about the physics here - both if the depressurization is equal or unequal. The video in question: | [
"Sure, any projectile in a cloud of gas is going to experience \"air resistance,\" whether that cloud of gas is on Earth or in space. The same basic principle applies in both contexts: the projectile has to push the gas out of the way in front, and this takes energy. In your case, a moving cloud of gas will exert a... | [
"Hitting gas at sea-level pressure at 300 m/s should be survivable with a good suit. People have used ejection seats at various heights and speeds. Does it slow you down fast enough so you don't crash into the next wall? That is another question...",
"Do we know for sure these two reached 340 m/s relative to the ... | [
"Thanks for both your answers. That’s also throwing me off about all this. The door opens, emits air pressure at a rapid rate, and even if that is survivable at the point of entry, would the atmospheric pressure when the door is closed create a cushion, a brick wall, or neither and they continue flying into the nea... |
[
"Why do allergy shots help? Why can't I just be exposed the thing I am allergic to once a week?"
] | [
false
] | I have a decent knowledge of how allergies work, but what I still don't understand is how allergy shots actually work. I understand that the shots are exposure to allergens, and that the dose increases over time. Therefore, the patient can tolerate greater and greater amounts of the allergen until they have reached an acceptable level of tolerance. But what I don't understand is why continuous exposure doesn't do the same thing. If I am allergic to, say, cats and I am around a cat once a week, why does the allergy continue to get worse (or stay at a certain level of severity)? Why does the body build up a tolerance through allergy shots and not repetitive acute exposure? Does it have to do with the graduation of doses of allergy shots? Thanks! | [
"Actually, allergy shots ",
"don't cause a \"tolerance\"",
" in the way you are thinking. What they actually do is change the nature of the immune response from one dominated by IgE and eosinophils to an IgG/T cell immune response. These different immune mediators still respond to antigen, but they don't cause ... | [
"Ahhhhh, that does make sense, thank you! I think the disconnect was that I thought the allergy shots still produced a reaction via IgE/eosinophils and the body just became used to it, or bored of it, haha. But that exactly answers my question, thank you!"
] | [
"Work the same way with Asthma allergy? If I get the shots will it only help the itching, watery eyes, sneezing. When I run into cats/dogs I really struggle to breath but didn't know if allergy shots would help that too... "
] |
[
"Why don't nuclear power plants use direct air cycle turbines?"
] | [
false
] | DACT were successfully spun up during the nuclear propulsion program but nuclear aircraft were not viable for obvious reasons. However they seem to make a lot of sense, why heat steam and run a turbine when you can run the turbine directly off the heat of the core? Wouldn't this be more efficient? | [
"No, so far we haven’t find anything is better than steam. You can look at the PV or TS diagram, steam give you the best result. Coal fired power plant do exactly that. But natural gas turbine will burn fuel at the turbine to generate power and send the exhaust to generate steam for more power, heat recovery steam ... | [
"The energy extracted from a fluid equals its pressure times its change in volume, so to get the most energy you want the volume to change as much as possible. The best way to do this is with a phase change, starting from a very dispersed gas and condensing it into a liquid.",
"There are a variety of condensible... | [
"If you want to be horrified then that's not just an off-the-wall idea I made up. About half a dozen multimegawatt ",
"mercury turbines",
" were built in the U.S. for power generation, mostly in the 1930s and 40s. The site has old photos of workers floating calmly on top of pools of liquid mercury...",
"Mercu... |
[
"If trees did not ever exist, would homo sapiens even exist, if yes then what would humanity look like in that timeline's 2014 in comparison to our timeline's 2014?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"For more information regarding this and similar issues, please see our ",
"guidelines.",
"If you disagree with this decision, please send a message to the moderators."
] | [
"Do you know a good place to ask this question besides askreddit? "
] | [
"/r/AskScienceDiscussion",
" "
] |
[
"Why doesn't 2,4-Dimethylpentane have cis or trans isomers?"
] | [
false
] | [deleted] | [
"You're right in your last point. There's free rotation about all the bonds in this molecule so there's no way you can configure the atoms that isn't equivalent to all the others. ",
"It is possible to make some non-equivalent isomers if you for example replace half the hydrogens with deuterium. In that case, you... | [
"Yeah, you need something to restrict the geometry so they can't easily interchange. This can happen a couple of other ways too, but they're not common."
] | [
"Yeah, you need something to restrict the geometry so they can't easily interchange. This can happen a couple of other ways too, but they're not common."
] |
[
"How does 5G achieve speeds orders of magnitude faster than LTE if they’re both just using electromagnetic waves?"
] | [
false
] | [deleted] | [
"The TL;DR is: The speed of radio waves is often not important at all in wireless communication.",
"Long answer:\nFirst of all, in communication systems there are usually two important measures that relate to the \"speed\" of the system. One is called latency the other throughput and only the latency is directly ... | [
"The biggest change between 4G and 5G is the transmission frequency. The fastest 4G networks transmit at 2.5Ghz, and the fastest 5G networks transmit at 25Ghz and 39Ghz. This represents at least a 10-16 times increase in bandwidth- potentially more if you're used to 4G operating at 600 or 700 Mhz.",
"There are ma... | [
"The biggest change between 4G and 5G is the transmission frequency. The fastest 4G networks transmit at 2.5Ghz, and the fastest 5G networks transmit at 25Ghz and 39Ghz. This represents at least a 10-16 times increase in bandwidth- potentially more if you're used to 4G operating at 600 or 700 Mhz.",
"There are ma... |
[
"Why does pure aluminum have such a high thermal conductivity, but such a low elastic modulus?"
] | [
false
] | [deleted] | [
"I knew keeping all my engineering textbooks would eventually have a use.\n\"Heat conduction is solids is moved by both lattice vibrations and free electrons. In high-purity metals, the electron mechanism is much more efficient than the phonon contribution because electrons are not as easily scattered and have high... | [
"Yes. Any material with free electrons will conduct both well. Then there are things like diamond that have no free electrons but conduct heat very well because lattice vibrations can easily move through the perfect crystal."
] | [
"is this why good conductors of heat tend to be good conductors of electricity?"
] |
[
"Where did the name \"The milky way\" originate from?"
] | [
false
] | null | [
"The ancient Greeks were IRC the first people to call the galaxy the Milky Way. In fact, the Greek word for \"galaxy\" derives from the Greek word for \"milk.\""
] | [
"Yes, it's Hera's breast milk that sprayed across the heavens when she breastfed Heracles."
] | [
"Seen from Earth, the Milky Way is a gigantic arch across the entire night sky, visible with the naked eye, many times wider than the moon.",
"It's only hard to see in the modern world because light pollution from cities makes it difficult to see from where most people live. To the Greeks, it would have been the... |
[
"When a Phase Change Occurs Because of Pressure Change (e.g. flashing of water), Does The Temp. Remain the Same?"
] | [
false
] | I was reading about the effects on the human body when exposed to near vacuum conditions (such as in space). When NASA testing this, their test subject reported the last thing he remembered before he began to lose consciousness was the water on his tongue beginning to boil. I assume this is because of the pressure of the water was below 1 atm and was beginning to change phase to a liquid? Would that be that be correct to assume? I imagine if, while the water was beginning to boil due to pressure, that if the temperature also changed it would probably be pretty painful. | [
"You are correct, the water on his tongue boiled because the pressure was so low. The ",
"phase diagram",
" of water shows the thermodynamically preferred state of water for a given combination of pressure and temperature. Assuming the test subject was in a near vacuum the boiling temperature of water in his ... | [
"I'm not sure of the article is question since I'm on mobile, but I don't think it's necessary. I'm just a sophomore undergrad, but I may be answer your question. If you've seen a phase diagram before, there are usually three curves that distinguish different phases of a substance at various pressures and temperatu... | [
"In the scenario you described, what happened was that once the pressure in the ambient environment was reduced enough, it fell below the vapor pressure of the water in the subject's saliva. This caused the water molecules in his saliva to push harder than the air was pushing back, and the water began to vaporize.... |
[
"What is the thin layer that forms on top of tea when it steeps too long?"
] | [
false
] | Well, title speaks for itself, I guess. I've noticed that when I let tea sit too long with the bag still in it, a transparent/white-ish layer forms on top of the water. The stronger the tea is, the more apparent it seems to be. For instance, it rarely appears with herbal teas, but with a strong Darjeeling, it takes no time at all. Can anyone tell me what that layer is and how/why it forms? Cheers! | [
"My guess would be various oils that are present in the tea leaves that sit on the surface of the water. "
] | [
"Do you live in an area with hard water? Could be that combined with the oils in the tea"
] | [
"It's a mixture of calcium carbonate from the water and complex organic molecules from the tea. Try filtering your water to soften it, or add lemon juice to lower the pH. "
] |
[
"Could Opportunity be in reach of Curiosity and see it?"
] | [
false
] | null | [
"Not really. Opportunity is ",
"here",
" and Curiosity is ",
"here",
"."
] | [
"Thanks!"
] | [
"Your question has been removed, but I'd encourage you to participate in the ",
"main thread",
" on the Mars landing. Right now, all Mars related threads will directed to that one."
] |
[
"If I were to stand in the middle of a completely sealed, spherical mirror with a light bulb in the middle, would the light build up to blinding levels, or just remain as bright as the bulb?"
] | [
false
] | Title basically says it all, but I imagine if you have a box full of bouncy balls, and you keep throwing them in there with infinite energy, adding more and more would increase the density of the balls in the box, so would the same thing happen with light? | [
"Short answer: for perfectly reflecting walls, it's gonna get hecka bright.",
"Let's start with what determines the brightness of an incandescent bulb. You've got some electrical power P being deposited in the resistive filament. The filament heats up to the point where that input power is matched by all the p... | [
"[EDIT: ",
"]",
"This is a point that begs for an estimate of timescales. ",
"First, let's estimate the timescale for radiation to fill the sphere so that it has the right energy density for a 2800K (say) blackbody. Since you're standing in it the room needs to be fairly big... to pick a round number let's... | [
"[EDIT: ",
"]",
"This is a point that begs for an estimate of timescales. ",
"First, let's estimate the timescale for radiation to fill the sphere so that it has the right energy density for a 2800K (say) blackbody. Since you're standing in it the room needs to be fairly big... to pick a round number let's... |
[
"Is there a difference in the quality of gas based on where it's sold. Is exxon gas better than walmart gas,etc.?"
] | [
false
] | null | [
"I refer to Cartalk hosts, the Tappet brothers.",
"\"Is there a difference in the gas between the big names, and the El-Cheapo gasoline at my local Costco or Stupey-Mart?",
"There is. A number of years ago, some of the major auto manufacturers were ticked off with the deposits from gas that met EPA detergent st... | [
"As someone who has worked on software for a pipeline terminal, gas is gas. Far be it from me to disagree with Click and Clack, but I don't think this tells the whole truth: The only difference between these Tier 1 and Tier 2 fuels is the additives. An Exxon truck pulls up to a terminal, pushes a few buttons (on... | [
"They call those 'Diesel' engines."
] |
[
"Is there a consensus on what is a dinosaur? How different were they from dinosauromorphs ?"
] | [
false
] | null | [
"Dinosaurs are defined as Triceratops, a house sparrow, and all descendants of their most recent common ancestor. You might hear a couple other definitions--sometimes Iguanodon and Megalosaurus are used the references instead--but they all amount to the same thing, which is basically ornithischians and saurischians... | [
"No, which is typical for large groups. Even if we happened to find an example of that species, we wouldn't have the evidence to say if it was the actual most recent common ancestor or a close relative.",
"Of the dinosaurs we have found, different analyses still disagree on which species is the closest to the anc... | [
"This is not possible. Most species exist as chronospecies, they differ slightly over time. H. Sapiens is a chronospecies including H. Antecessor, H. Heidelbergensis, all the way back to H. Ergaster. There's no defining moment between any of them, and forms midway between different morphologies are common.",
"Let... |
[
"How do center-surround receptive fields account for the Hermann Grid illusion?"
] | [
false
] | null | [
"They do not (in a lateral inhibition account). See ",
"here",
". "
] | [
"Yes. I've looked up the site. Thank you for sharing.\nI understand that there is much more that we do not know.",
"Let's ignore the argument that it is the \"weak\" explanation. I'd still like to understand how RFs work in the Hermann Grid illusion. Particularly when it's reversed (White Squares; Black Lanes). ... | [
"See the \"previous page\" in that link, which is ",
"this",
". It has an illustration of the mechanism / explanation. For white squares and black lines, it's just the opposite kind of RF (OFF-center instead of ON-center). "
] |
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