title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why do people in space need to wear space suits but equipment designed and built on earth works in space?"
] | [
false
] | Is it true that humans would explode in space due to the lack of atmospheric pressure if they weren't wearing space suits? If that's so, why does, say, a camera that was designed and built on earth not explode in space where there is no atmospheric pressure to push against the structure of the device? | [
"Blood, water, and other buildy fluids will want to evaporate I believe.",
"Yes but there are several examples of people being exposed to vacuum. The effects are well understood. ",
"Here is one example",
".",
"And wouldn't a computer very successfully radiant any heat away because space is so cold?",
"If... | [
"Is it true that humans would explode in space due to the lack of atmospheric pressure if they weren't wearing space suits?",
"Not really, but they won't be able to breathe so they would die quickly.",
"why does, say, a camera that was designed and built on earth not explode in space where there is no atmospher... | [
"Please don't read this with any snarckiness, even if it comes off in the way I type. ",
"Blood, water, and other buildy fluids will want to evaporate I believe. \nAnd wouldn't a computer very successfully radiant any heat away because space is so cold?"
] |
[
"How can photons carry electromagnetic force if they don't have charge ?"
] | [
false
] | I have a very basic understanding of standard model, and this question has been bugging me for awhile. Photons are the force carrier boson for electromagnetic force, which is the force between positive and negatively charged particles. The photon has no rest mass and has no charge. If it has no charge, how does it carr... | [
"It is not necessary that a carrier particle have a charge in the force that it transmits, but it is possible. I'll go over briefly why it is not possible for the photon to have a charge with the evidence we have (there are other carrier particles, like the gluon, that do have a charge of the force that they carry)... | [
"The electromagnetic force is the force between charged particles, yes, but why does that mean that the force carrier must be charged?"
] | [
"with regards to light, a good rule of thumb is that light travels as a wave but interacts with matter as a particle. This means that any interaction with matter - absorption and emission - must occur in discrete chunks of energy which we call photons.",
"Any stationary charged particle has associated with it a s... |
[
"I'm considering fasting for forty (40) days on nothing but water and a multivitamin. What precautions can I take to be successful?"
] | [
false
] | null | [
"What are your reasons for fasting? I'm assuming it is for weight loss. If that is the case then I feel the need to say that you can't replace proper nutrition with supplements. You will lose weight but once you start eating again it will come back on fast and possibly more. But fasting does have its health ben... | [
"Aren't there some individuals in studies that haven't put the weight back on?"
] | [
"I bet there are success stories with fastening and I believe in the long run it has many positive health benefits. It's just important to remember there will be some weight gain (even fat) when you start eating again. So to lose that weight and keep the other weight off you will need a good diet and adequate exe... |
[
"Why can't you see any stars in pictures taken from astronauts space walking?"
] | [
false
] | Here you can see Sunita Williams spacewalking. The thing is, I can't see any white spots in the dark black background. Why? Aren't you much more likely to see stars when you're not under the Earth's atmosphere? EDIT: Stars excluding the Sun | [
"The stars are simply not bright enough.",
"You can try that yourself, go outside and take a picture of something bright in front of the night sky. You won's see any stars."
] | [
"If you took a picture of someone and the sun was in the sky, would you see stars? ",
"It's slightly more complicated than that, but the same idea. Normally, the gases in our atmosphere scatter the sunlight during the day. That's why the sky is blue, and we have red sunsets. It's also why we can't generally see s... | [
"Stars are relatively dim and so require a long exposure. The vast majority of sky pictures showing stars are taken over long exposures, but another alternative is to take many photos and layer them on top of each other."
] |
[
"Why is micro (μ) the only prefix which doesn't use a letter from the latin alphabet?"
] | [
false
] | null | [
"We already use mega (M) and mili (m). micro also starts with m, the easiest way to keep the m but avoid confusion is to go to a greek letter. If you do not have access to greek letters you can also abbreviate it as u e.g. us or um for microsecond and micrometer, respectively."
] | [
"Funnily enough, the fact that it is often replaced by u is why most people aren't aware that the name of the popular torrent client is pronounced \"micro torrent\", not \"you torrent\"."
] | [
"On a full keyboard and on an operating system that supports it in the first place."
] |
[
"Why are some moles dark colored, and why do moles grow darker and longer hair than the skin around them?"
] | [
false
] | Why do moles seem to grow hair faster than skin on the same part of the body that is mole free? Also, could someone give me a good explanation of why moles are darker, and why some dark at all, but are just skin colored? Why is the hair they grow dark, even in light haired people? Thanks in advance! | [
"No one seems willing and/or able to answer my questions, so I will do my best to answer some of the questions using information I found from various places online.",
"could someone give me a good explanation of why moles are darker, and why some ",
" dark at all, but are just skin colored? ",
"Most benign mo... | [
"I recently had a few moles looked at for possible cancers. Protip from the doctor: moles with a hair growing from them are benign."
] | [
"It's one thing to say \"if you have moles you should get them checked out\", but you took my question, which I think is obviously just a question about how a biological process works, and claimed that it was soliciting medical advice. ",
"I think from the way I worded it it's very clear that it's not and, like I... |
[
"Why is a very small increase in average global temperature such a big deal?"
] | [
false
] | All of the apocalyptic "we're all gonna die" media seems to indicate that a one or two degree increase in average global temperatures will bring about massive consequences. Why? What's the big deal over such a small change? | [
"Because its not like we know how to cool it, the trend keeps going upwards and we have a general idea of how to stop it from warming up, but now how to cool it down. Furthermore, the more ice melts, the less there is to reflect heat into the atmosphere, and as ice recedes, frozen methane escapes into the atmospher... | [
"One degree increase in global mean temperature does not correspond to location X being one degree warmer at time Y. Many places will be much more than one degree warmer at certain times of the year.",
"Temperatures have risen much more rapidly in the Arctic than in more temperate regions.",
"Also, much of the ... | [
"To expand on what ",
"/u/PedroAlladio",
" said:",
"The problem is that the rise in temperature is a global average and not a few degrees in each location. A large amount of the warming will actually occur in the poles and, in addition to the ice melt, will relax the temperature gradient from the equator to t... |
[
"Is there anything that we eat that can make our weight increase by more than the weight that we ate?"
] | [
false
] | I know that 1lb of body fat is approx 4,000 calories. Does any food transfer to our bodies more than 4k calories by eating less than 1lb. Sorry if I am not explaining this well as I am struggling with describing the concept easily. TIA. | [
"Remember, a pound of body fat is more than just lipids. It is true there are more food calories in a pound of pure oil (4100) versus that which is estimated to be required to generate a pound of body fat (3500), but there is also a significant water content to adipose tissue.",
"The lard, suet, or whatever your... | [
"If you are discounting 'drinks' as food we 'eat', then you could eat a small amount of salt, and drink a large amount of water, and retain much of that water for a short time.",
"In that sense, yes. But in no other sense. Moving oil droplets into our cells does not magically create mass from the ether. Your body... | [
"but are there no foods that increase the amount that you retain of what you eat? such that if you did not eat the food you would not gain weight, but if you did eat the food you will gain more weight than the food weighs?"
] |
[
"Can all software be reverse engineered--how can you run a program and not be able to see its source code?"
] | [
false
] | null | [
"I'll assume you mean an actual executable file, like an exe-file on Windows, or this reply will get very long really fast. Those are programs that execute directly on the computer (on top of the operating system). Those programs consist of a bunch of machine instructions expressed as plain numbers, which are inter... | [
"Do they actually go through the process of attempting to de-compile the malware and analyze the resulting code, or is there some other method?",
"Good question, they don't. The decompiled code for such a program would be completely unreadable, if it is possible to get decompiled code at all (not including assemb... | [
"You could do that, and it's actually a good idea IMO. It is easier for people to differentiate between \"banana\" and \"apple\" than between \"var39\" and \"var27\". Sadly, it still won't help in understanding what's happening. Good practice is to use names that mean something and actually explain what's going on,... |
[
"Do any other primates chew their nails?"
] | [
false
] | null | [
"Do any ",
" primates chew their nails?"
] | [
"Do any ",
" primates chew their nails?"
] | [
"Nail biting in primates is a fairly well known stress response. You should keep in mind that, since other primates tend to use their nails as tools more often than humans, and since they lack our sense of vanity, their nails get more worn down and broken from regular use than our own."
] |
[
"Feynman theorized a reality with a single electron... Could there also be only one photon?"
] | [
false
] | From what I know about electrons, and the heisenberg uncertainty principle, you can either know exactly where an electron is at one time, or how fast it's moving; but not both. I've always wondered why the speed of a photon is the universal "speed limit". I know they have essentially no mass, which allows them to trave... | [
"And besides. \"Infinite miles per second\" seems like a better universal \"speed limit\" than \"186,282 miles per second\"...",
"And that's why we do experiments rather than imagine the laws of nature. \"Infinite miles per second\" was the speed limit in physics until our ability to measure the speed of light (... | [
"Time is a dimension of the universe. Imagine if you are flying in a plane to the north at \"186,282 miles per second\" and you start moving east. The more you move east the slower your speed to the north goes and the faster your eastward velocity. Once you have entirely turned east your northbound speed is 0.",
... | [
"The faster you travel, the faster you move through time.",
"It's the other way around. The faster you move through the space dimensions, the ",
" you move through time. And photons, which move very fast through space, consequently don't experience time at all (their time velocity is zero).",
"Formally:",
"... |
[
"Why do we have a tendency to say things like \"um\", \"like\", or \"uh\" repeatedly, and scattered randomly about in our speech?"
] | [
false
] | [deleted] | [
"I think you're talking about Filler words. Most of the time it's a pause you take to think about what you'll say next. ",
"http://en.wikipedia.org/wiki/Filler_(linguistics)"
] | [
"By vocalized pauses, do you mean the \"ums\" and \"uhs?\""
] | [
"Vocalized pauses indicate lack of confidence, knowledge, or general discomfort when speaking to groups."
] |
[
"Is there a psychological reason why people with NO attraction to their own family members, find incest so arousing?"
] | [
false
] | I was reading this thread: and started becoming extremely aroused. I've noticed this in the past when reading about incest or viewing incest-related material. By material, I mean incest-themed anime or stories, not incest pornography. Mentally, I know two things: I have zero attraction to my own mother or any other fam... | [
"There is a psychological effect known as the Westermarck effect which basically prevents us from having sexual attraction to our siblings. We are conditioned throughout our lives to seek sexual partners outside our immediate kin groups. One of the ways this manifests is in the dampening down of feelings of attract... | [
"As a somewhat relevant lesson, let me expound upon squirrel zombie's point regarding the crossover between fear and sexual excitation, because it's honestly one of my favorite studies in psychology. It is based on the ",
"two-factor theory of emotion",
", which says that for \"emotions\" to exist, we need both... | [
"FWIW, saying taboo words has been found to alleviate pain. ",
"http://veggierevolution.blogspot.com/2009/09/swearing-relieves-pain-new-neurological.html",
" ",
"Humans often use the word \"naughty\" as a positive descriptor of sexuality. This suggests that perhaps it's the actual 'forbidden' quality of p... |
[
"Why does an old open glass of water taste funny"
] | [
false
] | I've been looking around to try and find out a real answer to why a glass of water will taste funny if left open for a long time whereas a glass with a lid (not air tight) will taste pretty much just like tap water. I've read answers ranging from the mineral content is higher due to evaporation to gasses have escaped f... | [
"Yes. The Acid is the same acid that makes sparkling water sparkle.\n(There it is the other way around. A lot of carbonic acid is put into the water, so that CO2 will form.)"
] | [
"Because the melted Brita ice tastes like ",
"."
] | [
"Usually CO",
" is added to the water, not carbonic acid. The CO",
" reacts with water in equilibrium to create carbonic acid (thus also making the pH of most sodas moderately acidic).",
"I cannot say I've ever seen carbonic acid. The MSDSs I've used for it are basically for weak (1% or so) solutions of car... |
[
"Would the analogy between: an electrical short to ground, and a load with an infinite amp draw, be an appropriate comparison?"
] | [
false
] | null | [
"Yes."
] | [
"Thank you! Simple, concise, straight to the point. I appreciate it. ",
"Although, considering said concise answer, I guess maybe my main question is really: is it honestly that simple? ",
"Like, no \"reasonable/relevant\" caveats? No, \"yes in layman's terms but also you have to consider X, Y and Z\"? ",
"In... | [
"Yes, ideally speaking, creating a short circuit is to connect two nodes with a zero-resistance path, which is the same as a load which draws infinite current."
] |
[
"If a pregnant woman gets e.g. chickenpox, does the child get the immunity to it too?"
] | [
false
] | My mom had chickenpox when she was pregnant with me. I've never had it, and that's why I'm interested if I could possibly have an immunity? Also, I read that most of the few people who die of chickenpox are pregnant women. It seems that if you're pregnant, the chances of dying are much bigger. Also the fetus is in dang... | [
"It really depends. The answer is probably \"sort of\". It's been a while since i've done immunology so please forgive any mistakes.",
"The fetus does not have a fully mature Adaptive Immune system. This is the part of the immune system that conveys the \"memory\" to previous infections. The maturation of B cells... | [
"Not really. The acquired immune system doesn't pick up much activity until later in infancy. Also, the mothers immune system should, by traditional self / non-self logic, battle the fetus. There are some theories, but no conclusive answers, about how the fetus gets a pass from the mother's immune system. Something... | [
"immunoglobulin proteins, antibodies, aren't going to get passed across the membranes at this interface. They are much too large.",
"Maternal antibodies do in fact pass into the fetus",
". Specifically, IgG antibodies are imported by cells of the placenta and passed on to the fetus. "
] |
[
"[Physics] When boiling water on stove, why does water make a noise that gradually increase until right before boiling point?"
] | [
false
] | [deleted] | [
"I know exactly what you're talking about, OP.\nThe noise is caused by tiny air bubbles forming at the bottom of the kettle and then collapsing as soon as they leave the hot bottom surface. Once the entire volume reaches the boiling temperature the bubbles stop collapsing and instead reach the water surface, so the... | [
"The bubbles aren't full of air, its water vapor. There is no way for air to get to the bottom of the pot, and that's what boiling is anyway, water turning into vapor. "
] | [
"Yea I realized I mistyped but had no way of editing on mobile. You are correct, it's water vapor, however to be a pedantic ass, I'll say that there in fact is air. Cold water stores air and other gasses (like chlorine) that evaporate when you boil it. This is the reason boiled water tastes different from tap water... |
[
"What would happen to a laptop if you took a medical x-ray of it?"
] | [
false
] | Inspired by . Would the laptop take any damage? What if this were done while it was running? (I actually asked this question a month ago but I didn't really get a decent answer...) | [
"Nothing should happen to the drive, it's magnetic. I've put pretty much every laptop I've had through the x-rays at the airport. "
] | [
"Not really. It is possible that if it was operating, a few bits would get flipped in RAM, which might cause software errors. See ",
"http://en.wikipedia.org/wiki/Radiation_hardening",
"To damage the structure of the materials would take a lot more radiative dose than you get during a medical x-ray."
] | [
"I see. How about the hard drive?"
] |
[
"Is \"laziness\" just a matter of reconditioning your brain to release dopamine in response to different stimuli?"
] | [
false
] | Was reading in and the top responses intrigued me. How credible is the notion that eight weeks is the time it takes to drop an addiction and get "addicted" to something better? Does this work for almost any addiction/routine? | [
"According to ",
"this article in Time",
", it seems genetics may play a role. In nature, resting, and thereby conserving energy, is the primary activity of most animals when they aren't actively hunting or foraging. Humans (in affluent societies, at least), have little need to hunt or forage for food, so if we... | [
"Quick question, I find that I have a more \"addictive\" personality than most. I think I tend to obsess over things a little more than I probably should.. Any particular reason why that'd be?"
] | [
"Quick question, I find that I have a more \"addictive\" personality than most. I think I tend to obsess over things a little more than I probably should.. Any particular reason why that'd be?"
] |
[
"Compressed Liquid Oxygen/Nitrogen"
] | [
false
] | If you had liquid oxygen and compressed it enough so that it did not have space to turn to gas would it stay cold or would it get warmer even though its boiling point is so low? | [
"The problem with nitrogen (and other gases like it, including oxygen, hydrogen, helium, etc.) is that no amount of pressure will cause nitrogen to liquefy at room temperature. Nitrogen has to be much colder than room temperature to stay liquid. If stored at room temperature, a sealed tank full of liquid nitrogen w... | [
"Thanks! I didn't know there was such thing as a supercritical fluid so that makes more sense."
] | [
"If you had liquid oxygen and compressed it enough so that it did not have space to turn to gas",
"Compressing liquid oxygen will not cause a phase change to gas. To vaporize LOX, you must either increase it's temperature or lower the pressure. If the pressure is above the critical point, then heating will prod... |
[
"how much more radioactive is enriched uranium compared to depleted uranium?"
] | [
false
] | null | [
"The total activity is just the sum of the specific activities of the two neutrally-occuring isotopes, weighted by the mass of each.",
"A = m",
" a",
" + m",
" a",
",",
"or ",
"A/m",
" = (m",
"/m",
") a",
" + a",
".",
"The specific activities are constants, and the ratio (m",
"/m",
") ... | [
"Becquerel is a unit of activity. 1 Bq means one decay per second."
] | [
"what is bq?"
] |
[
"Will we ever be able to create shielding for Gamma radiation?"
] | [
false
] | null | [
"We already have shielding for gamma radiation. You just want a material with a high Z, like lead."
] | [
"That's just a dense material, I mean a mesh that absorbs the frequency. Also, lead doesn't absorb all the radiation, theoretically waveguides do because the eddy currents are dumped to ground."
] | [
"That's just a dense material, I mean a mesh that absorbs the frequency.",
"Gamma ray shielding ",
" just dense material. If you're talking about something else, then \"shielding\" isn't the term you're looking for.",
"Do you mean like a Faraday cage for gamma rays?"
] |
[
"How can the universe be flat if gravity bends space?"
] | [
false
] | null | [
"When someone says \"The Universe is flat\", they are referring to the Universe as a whole. The curvature of space as created by massive objects (i.e., gravitational curvature) is very, very small on cosmological scales, and this curvature is essentially just little bumps and ripples on the overall shape.",
"An ... | [
"A flat universe doesn't imply that it's flat like a sheet of paper, it means that two infinitely long parallel straight lines stay at the same distance along all their length.",
"In a positively curved universe, two infinitely long parallel straight lines would actually eventually meet/cross. And in a negatively... | [
"How is the universe flat? If you look up from any point of the planet there are stars right? Doesn't that mean we are in some sort of spherical shaped universe?"
] |
[
"If the Higgs field gives particles their mass, what gives them their charge?"
] | [
false
] | Or their respective quantities for the other two forces for that matter? | [
"There's often nothing wrong with writing down a theory where particles have a certain charge or mass, and a Higgs mechanism is not required to have massive particles. However, there are two cases, realized in the Standard Model, where explicitly writing down mass terms becomes problematic:",
"Massive spin-1 part... | [
"At a qualitative level, the Higgs mechanism does explain the masses of electrons, quarks, etc., but it doesn't tell us why these masses have the values they have. ",
"So what is the property that tells us things should have charge? There are invariance principles that underlie the laws of physics; these involv... | [
"The gauge boson mass terms are not gauge-invariant. That would seem to be a more fundamental stumbling block than anything to do with renormalization."
] |
[
"If low levels of non-ionizing microwave radiation don't damage living tissue are there applications where it would be useful to heat people?"
] | [
false
] | null | [
"It depends. I wouldn't think that all parts of your body would heat up at the same time - and there's a risk of denaturing proteins through the higher temperatures if you're not really careful with temperature control. For example, proteins in your eyes could become denatured due to their limited shielding for t... | [
"Microwaves are essentially just low-frequency infrared waves. We use microwaves/infrared radiation all the time to heat people, such as from campfires, fire places, and space heaters. A microwave/infrared photon has thousands to millions less energy then a visible light photon, and so it is much safer to biologic... | [
"I've seen articles in tech magazine (can't find them now obviously) about using low power microwave sources to heat people directly instead of an entire room. From what I recall, the microwaves don't penetrate deeply so they end up creating a warming effect on the surface of the skin only. ",
"I remember readi... |
[
"Relationship between altitude / temperature / vacuum?"
] | [
false
] | My kids were asking me why high altitude is colder than lower. The answer, I understand, is that the air is thinner. The thinner the air, the fewer air molecules colliding with your body and therefore less energy transferred to your body, and therefore colder. (correct?) But that got me thinking. Air is a good insulato... | [
"This is a commonly asked, but often times poorly explained question. I will do my best to explain it well. ",
"There are two parts to this question. The first is absorbing the Sun's heat. The atmosphere is mostly transparent to most of the energy the Sun sends our way (really, this is just a fancy way of saying ... | [
"One point of clarification. When talking about the upper atmosphere, you are really talking about the upper troposphere, the layer closest to the Earth, and where almost all of our weather originates. This layer extends up about 10km on average ( more at the equator, less at the poles), but above it, when you ente... | [
"Minor correction: as you go up in the atmosphere, the temperature drops until you reach the top of the troposphere, rises until you reach the top of the stratosphere, drops until you reach the top of the mesosphere, rises until you reach the top of the thermosphere, and drops throughout the exosphere (which does n... |
[
"How come in the creation of our planet, when asteroids collided with each other, they stuck together?"
] | [
false
] | null | [
"Huge chunks of rock are not bouncy. Their collisions are inelastic, meaning they don't conserve kinetic energy. The kinetic energy from their motion gets used up in breaking them apart and heating them up. That's where a lot of earth's internal heat comes from, actually. "
] | [
"Thanks for the well put answer!"
] | [
"I may be misinterpreting what you're saying, but the vast majority of Earth's internal heat is generated by radioactive decay. Earth is also of sufficient size to be able to use radioactive decay for heating, and could do so even more than 5 billion years in the future."
] |
[
"What is entropy and why must it always increase with time?"
] | [
false
] | null | [
"Entropy is the measure of the number of available microstates. Microstates are the number of possible configurations of whatever it is you are looking at.",
"So imagine you have a jumping pegs game like ",
"this",
". There are 6 pegs and 15 holes. Assuming my math is correct there are 5005 ways to put 6 p... | [
"Just to use the most simple thermodynamics example:\nIf two blocks of matter are firstly isolated and at another temperature (the number of energy packets in each of the blocks is not equal). If these are now thermally connected, energy (heat) can flow from one to another. If I now give you that all possible arran... | [
"It should be noted that in real life the statistical approach ends up saying things like \"you're right it's technically not a zero percent chance but if all the energy rearranges itself a million times a second it'll take a million times the age of the universe before it ever happens\"",
"So it really is neglig... |
[
"When humans exercise we sweat fluids that evaporate on the skin causing a cooling effect, which makes us great at endurance activities like running. Do other animals endurance levels increase significantly if it's raining?"
] | [
false
] | null | [
"Maybe slightly, but overheating is not the end-all determinant of endurance. Most animals considered to be good runners have ways of keeping cool. Horses sweat just like humans do while dogs pant, for example. The bigger factor in humans being so good at endurance running is our bipedal gait, which is a slower, bu... | [
"You're not wrong, our lack of insulating hair is definitely a factor in helping us stay cool, part of why we lack the hair that other great apes still have. My guess is that it would matter very little whether it was raining or cold or very hot because both human and animal would be experiencing the same condition... | [
"Thanks for the response! I agree that over-heating is not the only factor. I never really thought that other animals don't have this nice \"continuum\" of speeds that we have, and definitely agree with your example about dogs. This continuous range of speeds would definitely be an advantage. ",
"I'm aware of... |
[
"All the depictions of Pangea that I've seen show one landmass on one side of the globe. What if anything is on the other side? Or, did the landmass span around the globe and the representation is just for simplicity of illustration?"
] | [
false
] | null | [
"It's important to remember that Pangea was not the first supercontinent. The landmasses of Earth drift and clump on a fairly random cyclical basis. If you set a bunch of objects afloat on the surface of a sphere, it's inevitable that they will occasionally form a big clump before breaking up and moving on again. B... | [
"Why is Pangea the one we care about? Because it was the last one? "
] | [
"Yes, and this term originates from Alfred Wegener, who is the main proponent for the Continental Drift (the seed for Plate Tectonics)."
] |
[
"Can I get sick from a single bacteria cell? Or does it require a critical mass?"
] | [
false
] | I was cooking/baking the other day and was licking the spoon on the brownie mix when I remembered I put raw eggs in the mix which could be dangerous to eat before I baked it due to possible salmonella. I reasoned that a little taste wouldn't hurt me but I didn't lick it completely clean. This got me thinking about how ... | [
"The answer to this question, like so many other biology-related questions, is: it depends.",
"In this case, it depends on the particular species of bacteria you're talking about. Some species can cause an infection from just a couple of bacteria; others can need hundreds (or more!) in order to reliably infect a ... | [
"Now THAT is an excellent question, and it's a primary goal of my research to figure it out.",
"Again, this is somewhat species-specific. Some pathogens kill the host because, as you suggested, their growth outstrips the ability of the immune system to keep up. Others grow more slowly, but have specific mechanism... | [
"A single cell will almost definitely not make you sick, but it's also very unlikely that you will ingest only one cell. Where there's one, there's probably a small colony.",
"The minimum number of bacteria needed to make you sick is called the ",
"infectious dose",
". The number required depends on the speci... |
[
"Can anyone explain why HIV-1 is hard to cure?"
] | [
false
] | null | [
"HIV attacks cells in the immune system called CD4 T cells. Once inside they are able to replicate and produce more viruses. As they do this they mutate slightly so it is hard to target mutated viruses. It's also hard to vaccinate against it for this reason because a vaccine would \"train' the immune system to atta... | [
"Unfortunately, no. But there are ways to try and get ahead of the virus, so that these mutations wouldn't matter. These vaccine approaches are so-called \"broadly universal vaccines\" and are being tested for other viruses like influenza. (Further reading: ",
"1",
" ",
"2",
" ",
"3",
" ",
"4",
")",... | [
"HIV is a retrovirus. This means it infects your T cells, then actually integrates into - sticks itself in - the DNA of the cells, instead of floating around in the cell like most viruses do. Most viruses are making a bunch of proteins and copying themselves over and over all the time. Pretty quickly they kill the ... |
[
"What are the chemicals/molecules that make up tea?"
] | [
false
] | For a standard cup of hot tea, what exactly is inside the cup (other than water)? | [
"Wikipedia is your friend:",
"Health Effects of Tea",
"Mostly ",
"polyphenolic compounds",
"Specifically ",
"flavanols",
" and ",
"Catechins",
"Everything is in pretty low concentration, caffeine is probably the biggest component, but of course it depends on the tea. "
] | [
"I doubt anyone could tell you. It's dissolved plant extract, there are at least thousands of unique molecules."
] | [
"http://www.angelfire.com/pro/chemist_emily_f/chemistsinabigworld.html",
"A specific molecular formula not mentioned in the article is C8H10N4O2 caffeine. If you like John Kusack and want to see this formula used as a deus ex machina in a movie, track down a copy of Hot Pursuit. A funny and forgettable popcorn fl... |
[
"A question on random out comes and Time travel."
] | [
false
] | Im using time travel in this because its the only way I know to ask this question, although time travel isn't my concern lets just assume its possible. If something is truly random such as a slot machine or the lottery. Would going back in time (or re living a day-whatever works for the sake of this question) ,with t... | [
"I think this is an important problem in physics, and I think the answer is that we just ",
". When we talk about random processes, say quantum ones, we prepare a number of different experiments in the same way and see what the outcomes for each are. Then we say that, well since we prepared them the same way, the... | [
"So, if you were to be in a locked room and rolled the dice while I observed from the outside. Then I went back in time and observed from outside that room again you'd roll the same #'s because none of the \"conditions\" that caused you to roll those dice will be changed?",
"Not necessarily, even at the classical... | [
"For classical processes, the answer of a random process is determined by boundary conditions (determinism holds on the classical level). The roll of a dice is determined by the way you roll it. So if you would go back in time (and not disturb the boundary conditions) the roll of a dice, or the lottery outcome woul... |
[
"How long can a stable (non-radioactive) atom exist? Are they made of the same protons and neutrons as when they were created in a star?"
] | [
false
] | I assume electrons can be transient from electrical properties and chemical reactions, but I'm not sure about the hadrons stability or transience. Nuclear reactions excepted of course! | [
"Effectively forever. It's possible and indeed likely that any given hydrogen atom is primordial. Over long enough times, given or cosmology, it's possible that an otherwise stable atom will be perturbed by a high energy neutrino or gamma ray and decay. Free neutrons however decay in about 15 minutes. The experimen... | [
"That's probably not the best way to phrase it... the only theories that predict proton decay are not accepted, and we have ",
" on proton decay (as we do for most stable objects), but by that rationale it is \"unknown\" if ",
" stable objects decay. We believe they are stable because their halflives are longe... | [
"I think you go a little too far in the other direction.",
"by that rationale it is \"unknown\" if any stable objects decay",
"Right, it ",
" unknown whether anything is completely stable! It's good to acknowledge that when answering questions like this.",
"There are very good reasons to expect that protons... |
[
"Why do different oral magnesium salts (supplements) have different bioavailability measures?"
] | [
false
] | Hi all. I have always wondered why Mg salts are reported to have different oral absorption rates and bioavailability in studies. Isn't Mg in all oral salts paired with acids that are weaker than hydrochloric acid? Wouldn't all Mg then turn into MgCl2 and whatever acid made the salt in solution inside the stomach? I mus... | [
"This review",
" seems to conclude that solubility in water is the main factor. They also conclude that magnesium citrate was the most bioavailable with other organic salts being pretty close and with organic salts overall being slightly better than inorganic salts. "
] | [
"This isn't the place for hints or supplements. If someone were to ask a question \"why is CO2 a greenhouse gas\" and the answer was:",
"\"The easiest explanation is blackbody radiation. But the full answer requires much more advanced chemistry. Basically things vibrate and some vibrate in special ways. And that ... | [
"You're still not explaining anything. If you can write a dissertation, you can write a summary."
] |
[
"Where do the energy losses go?"
] | [
false
] | So I'm doing a read-up in a chemistry textbook and it says that burning natural gas for electricity is less efficient than using the direct combustion of natural gas. It goes on to say that the heat from the burning natural gas is used to boil water. The kinetic energy of the resulting steam is transformed to mechanica... | [
"Heat. Waste energy always goes into the most disordered state, which is heat."
] | [
"Think about it this way: at some point, the steam has to turn back into water so you can boil it again. So you have to cool the steam, which means that you take heat out of it. So there, you lose some energy to heat.",
"Secondly, all mechanical parts have some turbulence or friction associated with them. Both... | [
"It's mostly losses due to friction, so it's heating the materials that are in contact. This in turn heats the material around it, and on and on until it radiates into the surroundings. This heat may be carried away by some sort of cooling system, but eventually it has to be radiated somewhere."
] |
[
"They say that a photon takes a million years to make it out of the Sun. But what does it even mean? How do we define that a particular photon now is the \"same\" photon that was there then?"
] | [
false
] | [deleted] | [
"It would be more accurate to say: \"The energy from a photon released by a fusion reaction in the core takes about 1 million years to reach the surface.\" They start as gamma ray photons. Due to the density they only travel a short distance before colliding with a particle and being absorbed. That energy is re-emi... | [
"Plinko is a bad example I think. That game shows a single object actually making its way out. It might be more accurate to say that each moment the plinko disc hits an object, you stop it from traveling any further, and replace it with another disc, and repeat that process each time it hit something until it makes... | [
"Let me try my own questionable analogy:",
"\nIt's like one of those ",
"machines you drop coins into",
", except it's circular and unthinkably wide. There are quarters spread throughout, and when you drop a penny in and it hits a quarter that quarter shoots one or several pennies in random directions, which ... |
[
"[Physics] Would a hollow glass orb produce the same image as a filled glass orb?"
] | [
false
] | [deleted] | [
"No. When light travels through a medium there is something called the \"angle of refraction\". It ",
"looks something like this",
".",
"The angles in a solid sphere are different than the angles in a hollow sphere which is why the images would look different."
] | [
"Yes, that is what I'm referring to. I probably could have phrased differently \"The angles in a solid sphere are...\" though. "
] | [
"Yes, that is what I'm referring to. I probably could have phrased differently \"The angles in a solid sphere are...\" though. "
] |
[
"How severe is the problem with publication bias?"
] | [
false
] | null | [
"Anecdotal: Very. My adviser is THE GUY in his field. He puts his name on a paper it gets published. He hates that. He experimented by trying to publish a paper with a pseudonym and nothing. 6 months later he submits it with his name to a conference and he is asked to headline."
] | [
"is it even possible to blind the peer review/approval process? I expect that most research topics are narrow and specialized enough that peer-reviewers might be able to recognize someone's work much of the time even if their name isn't attached to it.",
"And if it is possible, is it something you think we should... | [
"It is blind one way (you don't know who is judging your work). But a judge does know the authors. And you are right I do not know if it is possible. Everyone in a small field knows what every one else is working on. You see them at conferences, you talk to them, you read their publications.",
"This is why for gr... |
[
"Do animals that live in total darkness still operate on a 24-hour cycle?"
] | [
false
] | null | [
"Is there anything that tells us why that is the case, evolutionarily speaking?"
] | [
"The 24 hour cycle in light-sensing organisms comes fairly obviously from the length of a day. The levels of gene expression within the cells of these organisms varies periodically, or that is to say, regularly. However, due to minor imperfections in these genetic clocks, a biological day is usually a little shorte... | [
"Nope. They did a study (sorry no link) that found when people spend months in darkness with ni external light source they tend to shift to 36 hours awake and 12 hours asleep, and in some cases even more of a difference. They also found that people were really productive on these schedules."
] |
[
"What exactly changes in a person's cognition and behaviour after a lobotomy? How do they live out their lives post-operation? The Wikipedia page is pretty abstract."
] | [
false
] | This comment is deleted | [
"I have Agenesis of the Corpus Collosum, essentially a natural lobotomy. From what I understand, my condition can manifest very similar to Autism Spectrum Disorder, as I definitely have. It is a bit different though, as I was born this way and my brain had to adapt to the missing pieces.",
"The brain is amazing... | [
"I just listened to a podcast episode of ‘Behind the Bastards’ about the guy who came up with lobotomies. Wild stuff. It sounded like some people actually had a decent life after their lobotomy, almost like they lacked any anxiety or intense concern about anything. In other cases it would debilitate the person to t... | [
"Full disclosure: I got all this info by listening to a podcast, and some quick googling. ",
"Moniz is certainly credited as the inventor of the leukotomy (later called lobotomy), but he never performed one himself as he wasn’t a surgeon. Both Moniz and Freeman learned of this procedure from a chimpanzee brain su... |
[
"Is the 13 billion years of existence of the universe relative to time as we experience it?"
] | [
false
] | Or perhaps to time as it would be experienced at a state of "rest" relative to the universe. I hope that makes some sense | [
"It's actually a bit wrong. The laws of physics are the same in every frames but the matter content gives a special frame (the FLRW metric is not boost invariant). So the cosmic time is not exactly the time we experience, since we are moving relative to this frame."
] | [
"The age of the Universe is defined in what we call ",
"cosmic time",
".",
"In the Universe, there is one special frame: the one in which the matter looks homogeneous and isotropic (=the same in all the directions). For example when we observe the Cosmic Microwave Background, we can see a special direction be... | [
"Wow. I never knew this. What direction is the earth moving relative to this inertial frame, and at what exact speed? And what is causing it? Is it the orbital movement of the solar system around the galaxy, and the fact that the Milky Way and Andromeda galaxy are moving towards each other; or is there more to it t... |
[
"Does the universe spin?"
] | [
false
] | So I know that pretty much everything is in motion within the universe. Stars, planets and galaxies spin right. I’m curious if our entire universe is spinning as well? | [
"A core idea in modern astronomy is the ",
", which states that on large scales the universe is both ",
" (the same in every location) and ",
" (the same in every direction).",
"If the universe were spinning, this would imply that it is rotating about some axis which would define a preferred direction, just... | [
"In order for the (observed, modeled) universe to spin, it would need a central axis upon which to spin. The observed, modeled universe contains structures of incredible scale, but nothing to indicate this particular piece of cosmological anatomy. There is no directional bias in the redshift of observed distant obj... | [
"We don't have to just look at the CMB - other observations such as that of the distribution of ",
"large-scale structure",
" support the claim that, at least within the region we can observe, the universe is homogeneous."
] |
[
"When my stomach rumbles what is actually happening?"
] | [
false
] | null | [
"could you verify that you are of the expert on this subject or at least provide respectable reference?"
] | [
"It all has to do with intestinal pressure building up. The more pressure you build up in the intestines, the more the feeling of \"needing to go\". Next time you are in the bathroom for a bowel movement, rock back and forth a few times to build up intestinal pressure. It makes the bowel movement happen much eas... | [
"It depends, there is certainly noise generated my the normal peristaltic contractions of the intestines but there are two specific noises that happen on a regular basis",
"One which is the movement of contents from the small intestine through the sphincter to the large intestine. This is done in one fell swoop t... |
[
"Do tides levels predict sinkhole formation in seaside areas?"
] | [
false
] | Apologies in advance if the question begs anti-science supposition about current events. The recent collapse of a condominium happened after two days of tides in excess of 3 feet (highest of the month), about an hour before the low tide. Naturally, I'm wondering if there has been any observed co-occurrence of tides and... | [
"I can't directly address sinkhole formation, but I can speak about the tides. First, the max tide range was today (Thursday, 6/24) with a high of 3.1 and a low of -0.8 (ft MLLW), not 3 days ago. Low tide was about 50 minutes after the collapse(01:30), at 02:20. That low tide was only -0.1 ft, however....the low ti... | [
"Differences in pressure (higher at surface/lower underground) can trigger a sinkhole to collapse. This article cites heavy rainfall or groundwater drawdown as potential mechanisms. Maybe low tide could draw the water level down if you are close enough to the coast but I do not know much about that. ",
"https:/... | [
"Low tide was about 50 minutes after the collapse(01:30), at 02:20.",
"So it turns out I was looking at the table for May!",
"Tides can be observed in groundwater wells, but the effects are small,",
"Yeah, I wasn't thinking it was a direct result of groundwater tidal force. More that it could be the pressure ... |
[
"In DNA replication, what is meant by 5'-3' orientation and vice-versa?"
] | [
false
] | null | [
"It has to do with the carbon number in the furanose molecule. The five prime end (5') is the fifth carbon in the ring and the 3 prime end (3') is the third carbon. The polymerase that forms the strand can only attach new nucleotides to the 3 prime end. So the first part of a chain would be a 5 prime end since it w... | [
"The 5' and the 3' refer to positions on the molecule, specifically the position of carbon atoms.",
"Adding to what ",
"/u/ColonelKick",
" said, the 5' end has a phosphate group attached and the 3' end has a hydroxyl group attached. ",
"DNA is read 3' --> 5' but DNA is synthesises 5' --> 3' (because you can... | [
"For questions like this I feel a picture will help a lot with understanding the answer. So OP, look at this picture for example, you can see 5 and 3 prime of each molecule marked:\n",
"http://universe-review.ca/I01-06-DNA.jpg"
] |
[
"What is the difference between neurological and psychiatric conditions? Is this distinction always so black and white?"
] | [
false
] | From my own rudimentary understanding - neurological conditions are well, physical in nature (as in they affect the brain physically), and psychiatric conditions are not. Is this entirely true? And is the distinction this black and white? Do neurologists end up having to pass off their cases to psychiatrists/vice-versa... | [
"Disclaimer: not an expert. However, I do believe that neurological conditions encompass some psychiatric conditions (for example, OCD, Tourette's, etc.). In fact, clinical psychologists and psychiatrists use neurological measures to test for many \"psychiatric\" diagnoses.",
"Basically, as far as I understand, n... | [
"Tishtok offers a good explanation, yes there are many interdisciplinary overlaps, especially as our understanding of the underlying causes of common psychiatric conditions increase. ",
"I just wanted to show the different uses the fields in practice with a simple example: ",
"Say a person walks into the emerge... | [
"It's not possible to answer these question because it will depend on your stance in the mind-body problem on which there is no consensus. If you believe that every mental state is reducible to the physical state of your nervous system, or that at least every mental state is caused by your nervous system, then you ... |
[
"How do coatings on solar cells increase the efficiency of the solar panel?"
] | [
false
] | If you have a coating with a specific index of refraction and then some sort of silicon cell with another index, how does the efficiency of the solar cell increase? I know that you generate different reflection coefficients, but how does minimizing the reflection coefficient actually increase the energy in the cell? Is... | [
"You seem to already have the answer. The goal of the anti-reflection coatings is to allow more light to be transmitted into the active layer of the cell rather than be reflected at the outer edge (e.g. the silicon/air interface). As a result less light is reflected and instead can be used to create more electron/h... | [
"It reduces the fraction of light that gets reflected, so more light enters the silicon. ",
"Here is a discussion",
"."
] | [
"For a specific wavelength I guess you can do much better, but in general overly complicated structures make it worse for other wavelengths."
] |
[
"Why can't we compare heat and temperature like ordinary numbers?"
] | [
false
] | Sorry if the title is a bit confusing, but it's a fairly simple question. I remember a while back seeing a story about a star which was listed as "1000 times hotter than the sun," and someone said it's not fair to say the star was "1000 times hotter" just because its temperature was greater by a factor of 1000. Why is ... | [
"It's important to note that your last sentence is only correct for non-thermodynamic temperature scales. Any thermodynamic temperature scale (0 point is at absolute zero) will give the same result for the ratio of two temperatures."
] | [
"Heat and temperature are two different things. We can't really directly compare them (although temperature is somewhat dependent on heat). For a pretty good explanation of their differences and the units involved, check out ",
"this page",
"*edit: Clarity"
] | [
"Ah, this is an excellent explanation! Essentially, because we have so many different temperature scales, temperature can be thought of as a somewhat arbitrary number, while heat is a measure of an amount of energy, and this quantity is thus not at all arbitrary (at least for my understanding--I suppose depending o... |
[
"What causes the conversion from matter to energy?"
] | [
false
] | I always hear that matter and energy are different forms of the same thing, but I never hear of the two existing in equilibrium. That would mean that matter/energy needs a metaphorical shove of some sort to be converted into its counterpart... | [
"Note: Energy isn't just a property of matter.\nPhotons aren't matter."
] | [
"Energy does not really \"exist\". Energy is not something you can hold in your hand. Energy is a property of matter; it is a way of describing things. ",
"I never hear of the two existing in equilibrium.",
"Matter and energy exist in equilibrium all the time. A baseball has mass, kinetic energy, gravitational ... | [
"That makes sense, although what I meant by equilibrium was something akin to liquid-gas equilibrium - I've never heard of a block of matter wherein particles spontaneously convert to energy and back..."
] |
[
"What ARE these? Saw this on the side of the road, looked SUPER cool, and now I want to try it!"
] | [
false
] | null | [
"They are really neat, but difficult to learn how to use. Look for jumping stilts on Youtube too for tricks."
] | [
"Ah! I wouldn't have thought to call them \"stilts\", thank you very much!",
"http://www.getflyjumpers.com/adult-standard-fly-jumpers.html"
] | [
"Ask gewgle for jumping stilts."
] |
[
"Why are car batteries 12v"
] | [
false
] | null | [
"In addition to that, the car battery keeps everything in the car powered and it generally has to get stepped down from 12v as it is."
] | [
"Lead-acid batteries are only 2.1 volts... for 12 v, you already need 6 of them. I imagine the overhead would get prohibitive if you packed too many more in the same size package. Significantly higher voltages are also a safety issue, especially with jumper cables."
] | [
"http://www.youtube.com/watch?v=rhIRD5YVNbs"
] |
[
"What's the importance of rocket engine exhaust gas velocity in terms of forces acting on the nozzle?"
] | [
false
] | I try to understand thrust of a rocket engine in terms of unbalanced forces ONLY (so please do not use Newton's 3rd law for explanation. I do understand it, however IMO it doesn't explain thrust, it just shows a relation between physical quantities). While I understand forces acting on a combustion chamber and a nozzle... | [
"The nozzle allows the exhaust gas to expand as pressure drops extracting as much energy as possible. The main source of energy in a rocket motor is heat and pressure from combustion. This is converted into kinetic energy by releasing it out the other side. There is really no other way to explain why that makes the... | [
"Exhaust gases by definition do not propel the rocket - they already left the nozzle, move in the opposite direction and have no contact with the nozzle whatsoever.",
"They do contact the nozzle, they expand against it, but contact with the nozzle is not needed to generate thrust from a strictly theoretical point... | [
"Greater exhaust velocity means the particles hit the wall harder or more often, otherwise they wouldn't have gotten a higher speed. How exactly that happens depends on what caused the greater exhaust velocity. A longer nozzle gives the particles more opportunity to hit the walls, a higher initial temperature gives... |
[
"What would theoretically be required to create a 'Faraday Cage Effect' on a Higgs Field?"
] | [
false
] | Would it be possible to create a space where the Higgs boson didn't permeate so particles in it were not exposed to it's field? | [
"No. (If the higgs boson exists and our model of the higgs mechanism is correct).",
"The vacuum expectation value of the Higgs field is non zero (due to spontaneous symmetry breaking). In very non technical terms this means that all of space is already filled with Higgs particles! The Faraday cage works by shie... | [
"When I said \"In very non technical terms this means that all of space is already filled with Higgs particles!\" I was being very non technical, so i'll take that statement back and clarify.",
"What it means to have a non zero expectation value is that there is a \"higgs charge\" throughout all of space, even wh... | [
"No is a bit definitive. ",
"Off the top of my head, I say yes. Unless I am having a dumbass moment it should be entirely possible... At high enough energy. After all he asked what would be required. Remember, even without SUSY, at high enough energy E&M and the weak force unify (Electroweak symmetery (un?)breaki... |
[
"Do Antipsychotics Cause Brain Damage?"
] | [
false
] | Hi everyone, I've read studies, from a few years ago, suggesting antipsychotics cause brain damage. Does anyone have any insight into this? | [
"Honestly, this is a very touchy and difficult subject. I'll start by saying I'm not aware of any evidence they are like, directly neurotoxic or anything.",
"Antipsychotics definitely create acute impairments, and some of their negative effects (ie metabolic dysfunction, reduced motivation, weight gain, etc) can ... | [
"You may be thinking of tardive dyskinesia, a movement disorder that can result from long-term use of D2 dopamine antagonists. It's not a cognitive effect and I don't think it is technically brain damage, but it can look similar to certain forms and can be disturbing to see.",
"More modern aka \"atypical\" antips... | [
"Thanks"
] |
[
"Why is the \"replacement level fertility\" (at which the size of a population remains the same) 2.1 children per woman and not 2.0?"
] | [
false
] | null | [
"This isn't correct. The replacement rate is an ",
" per woman, it doesn't care how many women actually have the children.",
"It's higher than 2 because of child mortality. In rich countries the replacement rate is around 2.1 but will be higher in places like the US which have higher child mortality. In poorer ... | [
"Because it’s a lot harder to get pregnant with your partner if you both have pussies?"
] | [
"Is this a real question?"
] |
[
"How can radio receivers pick out just a specific frequency wave?"
] | [
false
] | Doesn't the principle of superposition infer that all transmitted waves over all frequencies coalesce into one wave? Radios are around longer than computers so they can't be performing Fourier Transform to decompose the wave into it's constituent parts? Do radios built after advent of cheap and small processors perfor... | [
"Here's how it was done before digital radio:",
"The antenna picks up all frequencies striking out that are within its Shoreview range. Different lengths, different frequency ranges. ",
"This mishmash of signals goes through one or two stages of unbiased amplification. Meaning ALL of the signals are amplified. ... | [
"When they receive an interesting signal, they ",
" determine its source in many cases. Astronomical antennas are not singular receivers; they are arrays. Several antennas receive the signal, but there is some distance between them so signals arrive at very slightly different times. Using the delay between arriva... | [
"How difficult does filtering get for extremely sensitive devices such as in say radio astronomy, especially for unidentified phenomena where listeners might have absolutely no clue where it's all coming from one source, or maybe another source that is interfering? especially as there is no code per se like in Mors... |
[
"In Interstellar would the ship appear to be heading towards Miller's Planet for years or does time only begin to slow down once they have begun their descent into the planet's atmosphere?"
] | [
false
] | Since they spend 23 earth years on Miller's Planet what would it look like to Romilly who was still on The Endurance? Would he still see the ship in space heading towards the planet for years or would he not be able to see them? | [
"So, the orbital mechanics of Interstellar don't ",
" make sense. But yeah, if a spaceship moves very close to a black hole, an external observer would see them as moving much more slowly. The light would be emitted more slowly too, which would make them very dim. This would also make the frequency of the light g... | [
"The planet is in orbit around the black hole. Where is the ship? In orbit around the planet. The ship would experience the same effective time dilation as the planet. ",
"Additionally, the time dilation wouldn't be as extreme as shown in the movie.",
"You would think that they would get it right as they hired ... | [
"The way I understand it, that ship is powered by hand wavium. orbital flight in something the size of an RV is far beyond our technology."
] |
[
"Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"A table describing the position of a celestial body over time is called an ephemeris, and a collection of such data (plural) is called ephemerides. You can find extremely accurate tables of moonrise/moonset by looking up moon ephemeris.",
"This is my first hit on the search engine gives to-the-minute predictions... | [
"We probably should. I wasn't able to find anything specific but I'm fairly confident that the reasons are cultural rather than anything scientific.",
"",
"Of course there are those of us who believe we shouldn't bother at all... =)"
] | [
"There are a couple of facts about the universe (according to the cosmological standard model) that determine what we can observe:",
"First, the speed of light is finite.",
"\nSecond, the universe has a finite age.",
"\nThird, it expands at an accelerating rate.",
"Due to the first point, looking out into t... |
[
"Fasting: what are the effects?"
] | [
false
] | Google gives me crappy blog posts, and the best AskScience reference I can find is , which doesn't answer the question very well. What are the effects of a (water) fast for 24 hours? How about a week? I'd like to find out about all the effects: positive, negative, and neither. This is purely a science question - I'm no... | [
"Well let me just first say that it is altogether rare for anyone to fast for 24 hours straight. Almost all religious fasting is from sunup to sundown.",
"The fast on Yom Kippur, the most sacred of Jewish holidays, is a 25-hour fast. (That's not a typo, it's 25.)"
] | [
"believe",
"> ",
"/r/askscience"
] | [
"I wouldn't say it's rare. Uncommon maybe, but many, many fast for longer periods of time than 24 hours. I'm not sure why you advocate drinking tons of water. Your body doesn't need much water if it is not attempting digestion. Drinking tons of water on an empty stomach is just going to give you stomach cramps. ",
... |
[
"Is there a 'fantastic planet' out there? Could there be a terrestrial planet thousands of times the size of Earth, orbiting a Sun thousands of times as big as ours, inhabited by giant humanoids?"
] | [
false
] | [deleted] | [
"There are other scaling problems than just oxygen absorption. Strength is approximately related to the cross-sectional area of a muscle, but mass is proportional to volume. If you double in height your muscle cross section, and thus strength, go up by a factor of 4 but your weight goes up by a factor of 8. If you ... | [
"Maybe we are that planet, and there's a planet of really small humanoids somewhere. "
] | [
"Most replies deal with the planet's gravity, but there's a catch in the star's mass as well. The biggest star we've found so far has at most 150 times the mass of our Sun. Stars that massive have a puny life expectancy at a few million years at most. When you have such a massive star exploding in your face after o... |
[
"What happens to ants during a thunderstorm?"
] | [
false
] | [deleted] | [
"But wouldn't their tunnels be flooded during a rain storm?"
] | [
"I was wondering the same thing. During even a moderately rainy period where the ground gets soaked through, wouldn't the entire colony be flooded at that point? Most ant hills I see are made of pine needles and various things they collected... but I still don't see how they would withstand being flooded out. Can s... | [
"When electricity hits the ground, the ground is a very strong insulator, and the energy of the bolt disipates EXTREMELY quickly with distance from the strike. ",
"Ants right at the strike area would likely be incinerated, but even as far as ~10 meters (?) they wouldn't even notice it.",
"If I were an ant, I'd ... |
[
"Is dark matter the same thing as the Higgs Boson?"
] | [
false
] | [deleted] | [
"No.",
"Okay, so my understanding of the Higgs Boson goes like this: We have this theoretical Higgs ",
", with which fundamental particles couple to gain mass. The Higgs Boson is the fundamental excitation of that field in the way that a photon is an excitation of the electromagnetic field. ",
"And my underst... | [
"I agree completely - but wanted to add something.",
"One of the most obvious reasons that the Higgs boson is not a good candidate for a dark matter particle is that it is not stable. In a matter of well under 10",
" seconds it will decay into lighter particles, and at the end of the decay chain, one may get a ... | [
"Dark matter probably isn't \"matter\" because we would see it interacting with other particles.",
"Dark matter ",
" interact with other particles."
] |
[
"Can viruses be transfered by air, only by breathing into another person?"
] | [
false
] | [deleted] | [
"Your question is a bit cryptic. So I am going to assume you are asking whether viruses can be transferred via air/wind route, or only through breathing/coughing onto another person.",
"The answer to this question is actually dependent on the particular virus of interest. For instance, Influenza (flu virus) is ty... | [
"Wow, unexpectedly elaborate, tnx!"
] | [
"The measles and the chickenpox viruses can be transmitted via the air (hence patients' rooms go into airborne precautions), whereas the influenza virus needs droplets to survive (hence these patients go into droplet precautions). ",
"Source: ",
"http://www.cdc.gov/HAI/settings/outpatient/basic-infection-contro... |
[
"How does humidity affect drag?"
] | [
false
] | Do humidity levels affect the speed of an object moving through space, ex. a baseball, an airplane, a formula one car? According to aviators, the difference is negligible and not calculated in the aero. As far as I understand, humid air is less dense than dry air. But surely a baseball doesn't travel further on a 95% h... | [
"As far as I understand, humid air is less dense than dry air. But surely a baseball doesn't travel further on a 95% humid day vs 5%, given the same temperature and air pressure, right?",
"Why not?",
"There are Reynolds number effects, but they're much less significant than relative humidity (which itself is qu... | [
"It just feels like water vapor surely must create more drag than N and O molecules. But I guess not! Thanks for the answer!"
] | [
"To help you get your head around why it matters so little, note that even at 100% humidity, water vapor constitutes only a few percent of the air molecules. If you flew a model plane in a chamber with pure steam at 101 °C, and compared that to flying in 101 °C air, there would be a more measurable difference."
] |
[
"How to reduce percieved sound from an inherntly noisy bulding: a recording studio, inside of a practice building, in a residential neighborhood."
] | [
false
] | I have built and run a recording studio that is set inside of a building filled with practice spaces for bands. While our studio is well insulated and isolated from the surrounding band sounds, the building itself produces a lot of sound especially from people hanging out outside and talking really loud/being boisterou... | [
"It's more a matter of people talking outside of the building at odd hours. I am already ready to suggest mitigating this activity at the source by enforcing quietness outside of the building. But I was wondering if anyone knew of a way to ",
" the sound using acoustics..."
] | [
"If the studio is isolated enough to where loud practice spaces aren't audible how the H. can you hear voices from outside the building? Clearly your studio is not as insulated/isolated as you think"
] | [
"It's more the practice spaces surrounding us than the studio. You cannot even hear the studio from the hallway. We are just trying to help the landlord out with these sound problems."
] |
[
"How do chlorofluorocarbons (CFCs) reach the upper atmosphere?"
] | [
false
] | They say CFCs from old fridges and aerosols speed up global warming by catalysing the deionisation of the ozone. I also heard that CFCs are about 5x denser than air. How do they reach the upper atmosphere where the ozone is being depleted ? Does the atmosphere just fill with CFCs to saturation so they're everywhere ? i... | [
"Until 100km altitude turbulent mixing dominates and the entire atmosphere is well mixed, i.e. the relative concentrations stay constant. Above 100km in altitude diffusion becomes stronger than turbulent mixng and so the components of the atmosphere separate.\n",
"https://en.wikipedia.org/wiki/Homosphere"
] | [
"Mixed gases don't separate. If you have a large volume of lighter or heavier of gas, it will rise or sink as a collected mass. However, it will quickly mix with other gases. Once it is mixed, it doesn't separate based on density. This, the mixture of gas at height is approximately the same as on sea level. This of... | [
"Mostly through just regular air circulation patterns. Since CFC's take a long time to break down in the atmosphere, they spend a lot of time circulating around in the troposphere until the finally hitch a ride up into the stratosphere. The reason CFC's break down ozone is because they split when hit with enough UV... |
[
"Is it coincidence or simple logic that during both a lunar and solar eclipse the moon and sun respectively are almost perfectly eclipsed?"
] | [
false
] | The earth's shadow is just about the same size as the visible surface of the moon and the moon's apparent size is just about the same as the sun's apparent size. Would this be the case in any planet/moon/star setup or is that just plain silly? Could the earth's shadow just as easily have been a spot on the moon's surfa... | [
"Here is a composite photo of earth's shadow(penumbra) versus moon's size:",
"http://www.examiner.com/images/blog/wysiwyg/image/LEumbralshadow_ayiomamitis.jpg"
] | [
"\"The earth's shadow is just about the same size as the visible surface of the moon\" -- this part is not correct, actually earth's shadow at moon's distance is larger than the moon, so lunar eclipses do not have the tight fit as the solar eclipse.",
"\nThe moon's apparent size versus the sun is a coincidence. ... | [
"The earth's shadow is just about the same size as the visible surface of the moon",
"This is not the case. Lunar eclipses are not \"perfectly\" eclipsed. Rather, the Earth's shadow is rather larger than the moon, so there is more opportunity for blockage. This is why lunar eclipses are far more common over time ... |
[
"How can you tell what electric charge an object has?"
] | [
false
] | So if you look in textbooks that describe electromagnetic charge (the "rubber balloon rubbed on wool" is a popular one), objects will be identified as having a negative charge, a positive charge, or a neutral charge. I get that ... but is there a way to look at an object and know what charge it has? Can I tell if the... | [
"The definition of positive and negative charge is arbitrary. At some point, someone decided to name it this way around and that was that. We could swap the terms \"positive\" and \"negative\" around and nothing would change (we'd just have to update a lot of text books, manuals and other things).",
"So ultimatel... | [
"Yes, the words could be different. That's true of every word. So why bring it up (or is it down)?"
] | [
"You can tell by measuring the electrostatic field with a probe. Such things exist and are used for verifying static control in manufacturing electronics.",
"If you think, placing a metal plate near a charged object will cause electrons to either be attracted to or repelled from the plate. That will cause the vol... |
[
"Is a normal (no chimeras) human being's DNA the same throughout their body?"
] | [
false
] | For example, is DNA recorded the same way in sperm/eggs? How about in tumors? Skin cells? Hair cells? How common are errors and how would they affect things like cloning? | [
"Red blood cells lose their nucleus, so they don't have any DNA at all (except in their mitochondria, I suppose). Sperm and egg cells only have half of the normal amount of DNA, in preparation for the genetic mixing that all sexually reproducing animals use. Tumors are mutants, so they have a different genetic sequ... | [
"Unrelated comment, red blood cells also do not contain mitochondria. They rely solely on glycolytic reactions for ATP."
] | [
"Technically, no. Mutations and DNA damage happen.",
"Outside of replication-related mutations and DNA damage, there is actually a set of cells that contains DNA different from the rest of the body - T and B lymphocytes.",
"Both T and B cells are responsible for initiating the immune response after contact with... |
[
"From what I understand, if a cup is full to the brim with water and ice cubes, once the ice melts there will be no spilling. If this is true, why does melting ice caps mean rising sea levels?"
] | [
false
] | null | [
"The important ice is not that floating on the sea, but that which resides on land, such as much of that in/on ",
"Antarctica",
". This would increase sea levels if it melted, because it would flow into the sea."
] | [
"well, that sure makes sense."
] | [
"If all the floating ice in the world melted, it would cause less than 4 cm of sea level rise ",
"source",
". The main contribution to sea level is from ice that is currently grounded (on land) and melting; adding water to the ocean. "
] |
[
"What happens to light when it gets colder?"
] | [
false
] | [deleted] | [
"Light doesn't have a 'temperature', or at least, that's the wrong way of thinking about it.",
"Temperature as we commonly think about it is a measure of how fast molecules or atoms (ie, matter) are shaking-- or to put it another way, their thermal ",
" is in the form of moving bits of matter.",
"The energy o... | [
"Yes, the motion of objects is directed, the motion of atoms in a gas that makes up the temperature doesn't have a direction. The average velocity vector of a gas at rest is zero, as it must be, or the object would be moving. But the average magnitude of the velocity is not, and this is where temperature comes from... | [
"That cleared up A LOT, thank you! :D",
"On a side note then, is there a difference between the motion of objects(Like me and you) and heat motion inside our atoms?"
] |
[
"If Jupiter's \"Red Spot\" was here on earth, what damage would it cause?"
] | [
false
] | null | [
"It would engulf the entire earth in 1000km/h+ winds. The spot is a bit bigger than earth itself."
] | [
"The question doesn't really make sense. The great red spot is ",
" than Earth and is occurring in an atmosphere that's mostly Hydrogen and Helium. If it were here on Earth, our atmosphere wouldn't be."
] | [
"Thanks, sorry I wasn't more clear. I meant like what structures, if any, would remain, landscape changes, etc."
] |
[
"Will Saturn's rings eventually form a moon/moons?"
] | [
false
] | Since the matter is spread out around the body, in a similar way to the matter around the sun in the early stages of the Solar system, will this matter too go on to form bodies that will orbit Saturn? | [
"No, because they are too close to Saturn.",
"They are so close to Saturn that the tidal force from Saturn is larger than the attraction between two rocks of the ring. That's what we call the Roche limit.\nAnd actually it could be an explanation of their formation: a moon came too close to Saturn and was ripped a... | [
"Ill add some source for this",
"The best theory we have right now as to the formation of Saturn's rings comes from ",
"Robin Canup",
". If you'd like to read the full paper, PM me and i'll send you a pdf. Its one of the best I've read in the past few years.",
"Also the reason the rings won't coalesce int... | [
"As Coin-Coin says, most all of the material inside Saturn's Roche limit is doomed to fall inward to the equatorial region of the atmosphere of Saturn. Many/most of the rings were in fact a satellite that might have been impressive to see the breakup of. But it's at least several thousand years after the fact now. ... |
[
"It's sunny and warm outside, my curtains are black. Should I draw them to avoid heating my house?"
] | [
false
] | It's often recommended to close your curtains to prevent the sunlight from heating a room. But since dark curtains absorb more light than bright walls, wouldn't they emit more heat? Or is it better to keep the hot air between the curtains and the windows? | [
"If you leave them open, the sunlight that passes through the window will penetrate farther into the room, where it will be absorbed/reflected and ultimately converted to heat.",
"If you close them, they will absorb the light and heat up, but a small percentage will reflect back through the window.",
"So it sho... | [
"Keep them drawn. They will absorb the energy. Half of that energy will be radiated into the room, but half of it will be radiated back to the window.",
"For example, if your window is 1 sq. meter you get about 1500 watts of sunlight through it. Without the curtain, 1500watts of energy comes in and lands on the f... | [
"True. Windows are transparent to visible light, but block infrared. Unless your curtains are hot enough to start visibly glowing, they'll only emit infrared."
] |
[
"Is the double helix a representation of DNA as a concept, or could you actually see those patterns in a hair follicle or drop of blood if you had a good enough microscope?"
] | [
false
] | I've never been clear on how this structure came to be the lingua franca for discussing DNA. | [
"It's real. The actual molecule is much more complex than what you usually see because each nucleotide is composed of three subunits, each of which are in themselves complex, so you would have a hard time resolving a good image even with a powerful enough microscope, but the double helix arrangement is accurate."
... | [
"Taking some exception to ",
"/u/johnny_rico",
" , we can actually image individual atoms, just not with an ",
" microscope. Scanning Tunneling Microscopy is a technique the scientific community uses routinely now to image individual atoms. ",
"Here",
" is a relatively recent paper demonstrating STM of DN... | [
"It's safe to say you can't \"see\" because a light microscope will never get that resolution, but other microscopes can resolve the image and the visualization is accurate to the physical shape. Layman's terms in science communication is always fun. "
] |
[
"Is there an evolutionary benefit to eating spicy food that lead to consumption across numerous cultures throughout history? Or do humans just like the sensation?"
] | [
false
] | I love spicy food and have done ever since I tried it. By spicy I mean HOT, like chilli peppers (we say spicy in England, I don't mean to state the obvious I'm just not sure if that's a global term and I've assumed too much before). I love a vast array of spicy foods from all around the world. I was just wondering if t... | [
"Some spices kill some bacteria and fungi.",
"https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1745-4565.1984.tb00477.x"
] | [
"There's a recent paper that showed an association between regularly eating chili peppers and lower all cause mortality: ",
"https://www.sciencedirect.com/science/article/pii/S0735109719382063?via%3Dihub",
"It's still not causal, but those results could suggest that spicy food impacts our health in positive way... | [
"Except for black pepper, garlic, szechuan peppercorns, ginger,Daikon, radish, cinnamon, mustard et. al.",
"Hot peppers are not the only source of heat in spices. Most of these were used all through Asia and many were used in Europe at least back through Roman times."
] |
[
"Why is blue light the hardest colour of light to focus our eyes on?"
] | [
false
] | My robotics teacher mentioned that blue LEDs are used in keyboards and other indicator lights, as it's the hardest colour to focus on and we don't pay much attention to it. Googling around has verified that blue is hard to focus on but I can't find any credible research talking about it or verifying it, so is it the ha... | [
"I'm going to try to give you answers based on human biology, and the physics of light. ",
"First the Physics, blue light is scattered the most out of any visible light. If you take a look at the equations for ",
"Rayleigh scattering",
", the intensity of scattering is based off of the inverse of the wavele... | [
"It's a side effect of how your eye is structured.",
"\nOnly a small part of your eye can see fine details.",
"\nThis part of your eye happens to be where the 'red' and 'green' cones are most concentrated, but 'blue' cones are mostly found in the 'peripheral' parts of your eye.",
"\nSo in simple terms - the p... | [
"I think it's correct that the blue is hardest to focus on, but I do not think that that it's correct to say that we therefore don't pay much attention to it, nor do I think it's correct to say that either of those is why they are used as indicator lights. ",
"I think the real reason they are used is that for a... |
[
"Will shooting high-proof alcohol remedy food poisoning?"
] | [
false
] | null | [
"Notwithstanding the general proscription against seeking medical advice on reddit: No, it won't.",
"Food-poisoning can be caused by a wide variety of pathogens, which be either bacteria, viruses or assorted parasites. No two of them would react to alcohol the same way. Furthermore, it would have to pass the stom... | [
"I'm not aware that 14% alcohol [like in wine] is really that effective against salmonella [as the article implies]. Usually when you clean your hands with alcohol it's >60%.",
"Chances are if you're having wine with your chicken [for instance] you're eating at a classier place who have better cooks. It's proba... | [
"Well food poisoning can happen for other reasons too. Like eating chemicals for which your body can't correctly process (arsenic for instance). iirc alcohol will help if you ingest windshield fluid (not that I would recommend trying that) but that's about it.",
"What many people call food poisoning can also ar... |
[
"Sometimes when I'm about to fall asleep, I feel an almost electric like shock that jolts me awake."
] | [
false
] | null | [
"Do you mean a ",
"hypnic jerk",
"?"
] | [
"Well, I think we have solved this mystery! Thanks for the info. How did you know about this?"
] | [
">A higher occurrence in people with irregular sleep schedules is reported.",
"Maybe this is why so many people in this thread seem to experience it - too much late night Reddit and study."
] |
[
"Does Limestone pollute the water local to it?"
] | [
false
] | I am not talking about a mine. Rather a limestone bed in a totally natural setting that has water moving through it and dissolving the limestone. Does the solution that leaves the limestone bed pollute the waters that it reaches, or the surface? | [
"The calcium ions in water IS hard water."
] | [
"Limestone is just calcium carbonate. When water passes over it you get a lot of dissolved calcium ions, which can be problematic when the concentration is extreme, but short of that poses no concern. The biggest \"danger\" from water with high mineral concentrations isn't to people, but to plumbing. The minerals p... | [
"This is called \"dead\" carbon and is commonly caused by dissolution of carbonate rocks, as mentioned, or due to aging of oceanic bottom water. I just want to point out to anyone wondering that anomalously low 14C contents due to dead carbon is a very well known fact, and the reliability of \"shell dates\" is ques... |
[
"What is the addictive potential for pure nicotine for a non-smoker? Pure nicotine meaning without the monoamine oxidase inhibitors."
] | [
false
] | When I Google it I only seem to find information on cigarettes or sketchy sources. I really do not want to get hooked on anything which is why I ask. Also what health risks from using say, the patch? | [
"From wikipedia: \"Nicotine, a substance frequently implicated in tobacco addiction, has been shown to have \"relatively weak\" addictive properties when administered alone.\" It cites its source to a paper called \"Monoamine oxidase inhibition dramatically increases the motivation to self-administer nicotine in ra... | [
"There have been a lot of studies that show that not just smoking, but nicotine by itself is addictive. Long story short, we have a lot of receptors (nicotinic acetylcholine receptors) that are specific to nicotine, and the version of it that we produce naturally. Triggering these receptors stimulates the release... | [
"The patch does not contain pure nicotine, but also degradent products such as myosmine, cotinine, trans/cis-nicotine oxide, as well as matrix related products. FYI, the amount of nicotine actually in your patch is more than enough to kill you. The 21 mg systems contain 114 mg total IIRC. Only 21 mg are released... |
[
"Could a previously right/left handed adult train himself to be ambidextrous? If so how?"
] | [
false
] | Title says it all. Can you become fully ambidextrous if you previously had a preference for one side? | [
"I am not an expert in this field, but I was intrigued by the question, and figured this must be an issue that has been encountered by those who have lost use of their dominant hand for medical reasons. I found the following ",
"dissertation",
", entitled \"Injury-Induced Hand Dominance Transfer.\" The thesis ... | [
"There weren't any other comments, and it's frustrating to ask a legitimate question that nobody has an answer to"
] | [
"2nd good answer"
] |
[
"What is the molecular biology behind an allele being recessive or dominant?"
] | [
false
] | null | [
"The dominance of different alleles of a gene is largely determined by the nature of the protein that it encodes. For example, defects in structural proteins generally manifest as dominant traits because being heterozygous results in defective protein synthesis, which disrupts the native healthy protein. On the oth... | [
"Excellent explanation, I particularly like the truck analogy. "
] | [
"You should be more explicit in your explanations.",
"In this scenario, the heterozygote still has a loss of function, so we think of that trait as 'dominant'.",
"The dominant allele was the little b and the the recessive allele was the big B. This confused me for a minute since the common notation is that the ... |
[
"Does drinking water during meals dilute the acids and enzymes in the stomach, leading to poor digestion?"
] | [
false
] | A friend of mine got very agitated when I drank water during meals, saying that it is detrimental to digestion because it would 'flood my enzymes'. Is it true that drinking water during meals is detrimental to digestion? | [
"Almost certainly not to any significant extent. There are many factors at work that will effect the acidity and volume of the gastric contents. These will include how quickly the stomach is propelling the contents into the duodenum (gastric motility) and to what extent it is creating more digestive enzymes (gastr... | [
"There have been more than just that one study. This topic came up before and here was my answer:",
"http://www.reddit.com/r/askscience/comments/frz3r/gastroenterologists_does_drinking_water_or_any/c1i7otb",
"I constantly hear this but have never seen any solid evidence in support. ",
"There is in fact benefi... | [
"To be quite honest about that study, however, 100 mL of water 2hrs before surgery was a design failure asking for irrelevance. For safety reasons they probably didn't feel they could ask patients to drink more water closer to surgery, but the small bowel absorbs dozens of liters of water a day and I'd guess the tr... |
[
"Has there been any attempt of genetically modifying trees to yield wood with better material properties?"
] | [
false
] | Would it be possible? or is there something intrinsic to the nature of trees or wood that makes this impossible? Could a superwood be created to replace metals in some applications? | [
"To create a \"superwood\" would take an incredible amount of modification. obviously some woods (i.e hardwoods) are stronger than others (i.e. softwoods), but think of wood almost like human tissue. The consistency is dependent on the biology of the plant, its necessities, and how it grows. It's very possibly to ... | [
"As the strength of wood is normally linked to the speed of the tree growth, i don't think it's possible to make fast growing hard wood withoud extreme measures. Also we are able to reform the structure of wood to improve it's properties, but rather to replace plastic with a regrowing material because crude oil wil... | [
"Yes! Trees encode for a wide variety of proteins, all of which interact in complex ways to build their physical structure, but nothing about wood makes it impossible to tinker with those properties.",
"One group has been looking at the structural properties of aspen with a modified ferulate 5-hydroxylase. It had... |
[
"What do they mean by \"information\" when they talk about information being/not being destroyed in black holes?"
] | [
false
] | I've tried looking this up and understanding it, but for some reason it just goes over my head. What is "information" in this astrophysical definition? | [
"The word information is used in a very broad sense here.",
"In quantum mechanics, two different initial states cannot evolve over time into the same final state; they will evolve into two distinct final states.",
"In (non-quantum) general relativity, two different initial states can evolve into identical black... | [
"Modifying quantum mechanics to allow different states to evolve into the same state undermines a core, central feature of quantum mechanics. On the other hand, we know general relativity needs to be modified to account for quantum mechanics, and there is no core problem that would arise if the modifications gener... | [
"Is there any principled reason we think that the resolution will end up preserving information? Or do we just have a strong conviction that the quantum side of things is probably right on this?"
] |
[
"Realistically, how far away are we from solving the mystery of abiogenesis?"
] | [
false
] | null | [
"Biology"
] | [
"Biology"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"A good home for this question is our sister subreddit ",
"/r/AskScienceDiscussion",
" because of its open-ended or speculative nature. Please feel free to repost there!",
"Please see our ",
"gui... |
[
"Why is molecular polarity important to know?"
] | [
false
] | There is the "like dissolves like" argument and how water dissolves polar substances more easily than nonpolar, but is there anything else students need to understand? I was thinking about doing a project on oil spills or detergents and investigating polarities, but want to be absolutely sure I know what I am doing fir... | [
"You're already touching on the answer: the reason polarity matters is because it (and other atomic-scale factors) are what give a substance its macro-scale properties."
] | [
"It certainly goes beyond the ability of solutions of varying polarity to dissolve substances of the same polarity. The folding of proteins is largely determined by the presence and position of the side groups of amino acids present on the polypeptide. When in water, hydrophobic (water hating, like oil) side groups... | [
"Thank you. Are you talking about hydrogen bonding and London dispersion forces when you talk about macro-scale properties?"
] |
[
"What makes platinum so good as a catalyst for fuel cells?"
] | [
false
] | null | [
"Note that the question originally asked for platinum, but since palladium and platinum are in the same group I assume the answer is basically the same either way."
] | [
"Catalytic reactions occur in a few basic steps. First, the reactants adsorb onto the surface of the catalyst. Then, the reaction occurs. Finally, the products desorb from the surface.",
"In general, a catalyst is \"good\" when the adsorption is favorable (or else the reaction won't happen very fast), but the des... | [
"There are many reasons that palladium is so good at catalysis in general. One is that its Pd-H and Pd-C bonds are not too polar. This gives them a lot of stability towards water and other functional groups that organic molecules typically contain. Their bond strength is not too strong or weak, making them easier t... |
[
"why do fermions follow the pauli exclusion principle but bosons do not?"
] | [
false
] | null | [
"Fermions are ",
" to be particles whose multi-particle states are totally antisymmetric under particle exchange. And it's a direct consequence of that that the state vector vanishes if any two identical fermions have all the same quantum numbers. For bosons, the multi-particle state is totally symmetric, and the... | [
"Yes. Fermi-Dirac statistics is the statistics of many identical fermions."
] | [
"Thanks, and is that like the Fermi-Dirac statistics? "
] |
[
"What is the destructive capability of anti-matter?"
] | [
false
] | [deleted] | [
"Just use e=mc",
" and bear in mind that about half the energy released will be in neutrinos that don't really interact with anything, and voila."
] | [
"Um, massive.",
"The total matter conversion of the Hiroshima Atomic bomb was estimated at between 2 and 5 grams.",
"1 gram of antimatter would result in 2 grams of matter conversion to energy. Nuff said."
] | [
"I'm not sure what profession GeneralRobert is, but a very common application of positrons are in PET (positron emission tomography) scanners in hospitals. The basics of it is you ingest/get injected by some type of radioisotope, usually some isotope of fluorine with a very very very small half-life (most completel... |
[
"What is it called? Being around people you think are smart, which in turn makes you feel smarter?"
] | [
false
] | null | [
"It's called reason. If you have learned something from that person, you are smarter than before you learned it."
] | [
"Something like this? ",
"http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect"
] | [
"While that IS a very interesting study. Thats not quite what I'm meaning. You know thinking on it even more. The feeling you get when you learn something from people you admire."
] |
[
"Why is there no standardized way of measuring speaker-system audio quality? What makes it difficult to objectively assess?"
] | [
false
] | Sure, there's a big subjectivity factor. But I would have thought there would be a way to holistically (or otherwise) quantify clarity, fidelity, warmth, space, and all the other things audiophiles seem able to discern, but technology apparently can't. | [
"The biggest hurdle is that the impact of the signal's ",
"phase",
" on a human's perception is not ",
"fully understood",
". This makes it harder to objectively conclude signal A is better than signal B since some measure of A is less than some measure of B; presumably any measure which allowed for a defin... | [
"Your problem here is philosophical, not scientific.",
"There are plenty of objective measurements you could make. The most common one used to characterize a speaker is ",
", describing the intensity with which the speaker produces each frequency. ",
"But you can't objectively define terms like 'clarity' or '... | [
"There's a bunch of stuff that can be measured, but some of the measurements require expensive equipment and facilities, and even once you get that, translating the measurements into quality metrics isn't easy. For one thing, if you are comparing two speakers, one might be better in one respect, and another better... |
[
"Can anyone tell me what this bug/beetle is?"
] | [
false
] | null | [
"That my friend is a ",
"Rosemary Beetle."
] | [
"found it and got sad another time for not buying a better cam before the trip :/",
"picture of the fruit",
"taken between june and august 2005 (though seasons shoudn't matter there) in western Kenya, near lake Victoria.\nI'd say up to 5 cm in length.\nThe photographed one wasn't ripe at that time (but still ta... | [
"For future reference:",
"Give us some context - where/when was the picture taken? What's the approximate length?",
"There are better subreddits for this:\n",
"whatisthisbug",
", ",
"entomology",
", ",
"species",
", ",
"animalid",
".",
"I approved the link, but try to make the questions more u... |
[
"What is the efficiency of protest marches and public demonstrations to change policy and what do we know about the factors influencing this efficiency?"
] | [
false
] | Many people consider the public display of dissent with the current political or social status quo a hallmark of a modern democracy. Because of this the right to peaceful assembly and freedom of speech are protected in most democratic constitutions. There are also without a doubt examples throughout history where demo... | [
"I too, would like to know the answer to this question from someone with professional/scholastic insight on the subject. History has a number of great examples that showcases the success of such activities. But when we consider more recent events, it seems to either fizzle or have mixed results at best. I'm thin... | [
"Marches are often accompanied by encouragement to call state representatives and postcards are often given out at the Women's March to send mail to government officials. Marches let individuals know that other people stand with them in dissent. Publicity/social media circulation let a wider audience become aware o... | [
"Since the objectives, methods and scale of protests vary it's very difficult to assess effectiveness because you're not comparing like with like. The best we can do is list examples that worked and examples that didn't. In the former category would be protests that led to revolutions: the Arab Spring, Eastern Euro... |
[
"Is a complete simulation of reality impossible ?"
] | [
false
] | null | [
"Then, if you've consumed all of the universe and converted it into storage, you don't have much left to do any computations with."
] | [
"Also, I think to encode all the information of the universe, you'd need stockage as big as the complete universe."
] | [
"Chaos theory is another reason why pretty much any simulation of a system as complex (chaotic) as reality would be impossible due to the sensitivities inherent in the initial conditions of said simulation. It would be IMPOSSIBLE to gather enough data points with enough precision as you'd need an infinity of data p... |
[
"For alot of humans external temperatures above 20-25°C can be fairly uncomfortable. How do much smaller animals, particularly small insects, manage the heat?"
] | [
false
] | null | [
"Social insects have a lot of neat adaptations to keep their nest spaces cool. For example, the placement and angles of tunnels in a termite mound facilitate air flow and cooling:",
"http://www.planetseed.com/relatedarticle/cool-termites",
"Honey bees will forage for water on hot days, spread the water on the ... | [
"It is important to remember that the ratio of surface area to volume increases as an animal's size decreases, so it is in fact easier for smaller animals to get rid of waste-heat than for larger animals (and subsequently harder to retain it in cold weather)."
] | [
"Not insects, but I've seen more than one earth worm completely charred on the street during hot summer days. Perhaps insects and their better mobility allows them to escape such fate, but it is possible, it seems.",
"Also, taking into account that some insects like some species of bees can actually kill their pr... |
[
"What causes the 4 point twinkle effect on stars?"
] | [
false
] | I can't help but notice how stars always have these 4 lines extending from the center. What causes this effect? Also why is it that some have different colors in the lines (you can really see this in the Celestial Spiral pic)? Examples: | [
"That is not a twinkling effect; all the pictures you posted were taken by Hubble, which is above the effects of the atmosphere. What those are is diffraction spikes. In the types of reflecting telescopes used today, the secondary mirror is typically suspended above the center of the large primary mirror. In ord... | [
"at work so can't find the source right now but there was a Deep Sky Video on Youtube (",
"https://www.youtube.com/user/DeepSkyVideos",
") where they actually talked about how they've managed to adjust he shape of the spider's arms so the diffraction spikes don't appear, but for pictures they're publishing for ... | [
"It crap/scratches on your glasses lens. Diffraction occurs just as well around scratches/imperfections in materials as it does around free-standing obstacles. You should also be seeing it on streetlights, car headlights, etc. The halo is from oils, dust, and other crap physically sitting on the lens; ever notic... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.