title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Question on why we see stars on earth but not in outer space"
] | [
false
] | Well when we look up at the night sky we see many distant stars and galaxies, but when you look from outer space you don't see anything. Or at least that is what i noticed in and . Well to be fair you do see some in the second picture but much less than what you would see from Earth. I have a feeling it has to do with ... | [
"mostly because of how cameras work. They're usually pretty bad at capturing stars ",
" a scene at the same time. One is very dim (stars) and the other is very bright (scene). You can overexpose the scene to get the stars if you want, but then... bleh. I've heard that often in movies the stars are added back in t... | [
"It's a question of ",
"\"dynamic range\"",
". The bright parts of those photos are so much brighter than the stars that they they are indistinguishable from black.",
"Here's a picture of the ISS and the aurora",
". On the nightside of the Earth. If you look closely, you can see Orion's Belt."
] | [
"The shadow in the first photo indicates that it was taken during the lunar day, so any stars would likely be washed out.",
"I can see at least a dozen stars in the second photo."
] |
[
"How are all snowflake patterns unique, but every branch on the same snowflake is (relatively) the same?"
] | [
false
] | Snowflakes don't have much deviation in the patterns of their 6 branches, but all snowflakes themselves are unique from each other. What phenomena is happening that keeps the same pattern throughout any one snowflake? | [
"Sorry, I totally misread your question! The link you provided is broken, but I assume you were referring to ",
"shapes like this",
". To be fair, ",
"most snowflakes are irregular",
", and I do know that the crystal shape depends on the precise temperature and humidity of the environment where the snowflak... | [
"A snowflake weighs about ",
"0.002 grams",
". This is about 0.0001 ",
"moles",
" of ice, or about 6*10",
" molecules of ice, in each snowflake. Because of the various imperfections that occur when snowflakes accrete in the clouds, the odds of two snowflakes having the exact same arrangement out of this h... | [
"That didn't really answer the question, but thanks anyway."
] |
[
"Were the supermassive blackholes at the center of galaxies supermassive stars at one point?"
] | [
false
] | null | [
"No, a supermassive black hole would generally start from a single black hole that then expanded via accretion of matter and by merging with other black holes.",
"There is nothing called a supermassive star, the biggest stars are hypergiants but they are not thought to collapse but rather explode at the end of th... | [
"/u/arcelebor",
" summed it up pretty well, I iust wanted to add a little context. ",
"A star is a collection of gases that coalesce into a ball with enough gravity that molecules begin to fuse in its core. The explosive energy of the fusion reactions pushes the outer layers of the star out. The balance betwe... | [
"Thats what accretion of matter means. Its that and merging with other black holes."
] |
[
"Why is it so difficult to breed animals in captivity?"
] | [
false
] | null | [
"Hi SaxMan00 thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the follow... | [
"Biology"
] | [
"'Biology'"
] |
[
"Is time and light unrelated?"
] | [
false
] | [deleted] | [
"What specifically are you asking? In your title, word \"unrelated\" is vague. ",
"An argument relating Light to Time may go as follows: Light and time are related through the the constancy of the speed of light in vacuum."
] | [
"You really need to explain what you're asking a little more.",
"RRC asked how you got from time to light because you seemed to attempt a proof of existence \"out of time\" by proposing a universe in which there were no stars to make light. Now, I'm no professional in that field, but that doesn't seem a really c... | [
"In a totally dark universe, what is there to messure time by?",
"The same kinds of things there are to measure it by now. Any simple harmonic oscillator will do. A pendulum, for instance.",
"Would time exist?",
"Yes. It's no more meaningful to ask whether time could \"cease to exist\" than it is to ask wheth... |
[
"Why do we keep talking to our pets like they can hear us and understand us?"
] | [
false
] | null | [
"There are pragmatic reasons to do this. Many pets will be soothed by a soothing tone of voice, and some may actually recognise your voice. Dogs and cats may actually recognise a small vocabulary. (Self deleting a bunch of anecdotes about my cat here!)"
] | [
"Why do we keep talking to our pets like they can hear us and understand us?",
"Well most pets aren't deaf so they can hear you. Even deaf ones might be able to see your facial/body language. As for understanding, many pets can be taught to obey verbal commands. They can likely understand tone and disposition ... | [
"My pet Graveler disagrees."
] |
[
"Are skinny or wide tires better in the snow?"
] | [
false
] | When it comes to winter driving would narrower tire be more effective (My logic here is more wight over a smaller area = more grip, especially coming from a stand still.) or would a wider tire be more effective (more surface area = more grip?) I guess it would matter a lot what kind of tire you're using so figure for a... | [
"Car nerd here: though a wide tire ",
" give you more grip on an even, smooth road, such tires have real problems with hydroplaning on wet, snowy, and icy roads. Thus, ",
"snow tires",
" are narrow to try get maximum force at a small area (biting into the snow more effectively) and have less water under the t... | [
"Agreed. If the snow gets deep enough, you're better of with ",
"tracks",
"."
] | [
"Another point to make is when driving off-road in snow (especially with a 4x4), a wider tire with lowered pressure can help the car \"float\" over snow without cutting down to the ground. Here's a ",
"nice writeup",
" on some off-road driving techniques to use on different surfaces (scroll down for snow)."
] |
[
"If I turn down my house thermostat 3°F when the outside temperature is 0°F, does it save me any more money than turning down my thermostat 3°F when the outside temperature is 32°F?"
] | [
false
] | null | [
"To be fair, at first I thought you meant turn your thermostat down ",
" 3F as opposed to turning it down ",
" 3F."
] | [
"Stand back, I know applied thermodynamics!",
"While most of the things I've modeled have contiguous surfaces you should be able to apply log mean temperature differences to your problem with a grain of salt.",
"What's a log mean temperature difference, or LMTD as we in the biz say? Simply put it's a way of ca... | [
"cavercody is correct. The colder it gets outside, the more frequently you will hear your heating system cycle on. If you reduce the thermostat, you will reduce the frequency of the heating system cycling on, but you might not notice it at a 3 degree change."
] |
[
"Can 1 strand of mature mRNA be translated into multiple Proteins?"
] | [
false
] | null | [
"There are two terms to describe what you are talking about. ",
"Monocistronic",
" (one protein per mRNA) and polycistronic (multiple proteins per mRNA). Monocistrony is most common in eukaryotes and polycistrony is most common in prokaryotes, but these are not exclusive. Sadly I can not think of specific examp... | [
"A significant portion of any bacterial (or viral) genome will be polycistronic. The lac operon is probably the most well known example."
] | [
"yes, you can get multiple proteins from a single transcript. c.elegans has a good number of polycistronic transcripts.",
"recently, uORFs have been explored a bit in higher eukaryotes. these tend to code for short peptides (10s of amino acids) and are located upstream of the canonical AUG start codon. they are t... |
[
"Can we cool Venus with comets?"
] | [
false
] | null | [
"Actually the best way to cool Venus would be to heat it up.\nThat is, heat it up, add a bunch of Hydrogen gas and a lot of nickel as a catalyst. The hydrogen would react with the CO2 leaving behind water and 10% more heat, as well as lots of graphite and a 3 bar nitrogen atmosphere. The temperature would peak arou... | [
"You have to take into account that you are dropping the comets down the venereal gravity well. The energy gained has to go somewhere too.",
"A quick calculation tells me that 1kg dropped onto Venus gains about 60MJ in kinetic energy. That's more then enough to melt ice into steam and then some. Water being prett... | [
"Chill the atmosphere every 6 months with a temporary cloud of dust and water vapor. Every season you add more till it's cooled off enough. ",
"And for the months it orbits in the cloud,... you might need need supplement light to grow plants. (you might use a planetary aurora for lighting)"
] |
[
"If we sent a signal with our location to a civilization ANYWHERE in space, what would our \"address\" look like so they could find us?"
] | [
false
] | null | [
"We already did this with the voyager disk as well as plaques on Pioneers 10 and 11, (for our own galactic neighbors to find).",
"http://en.wikipedia.org/wiki/File:The_Sounds_of_Earth_Record_Cover_-_GPN-2000-001978.jpg",
"The drawing in the lower left-hand corner of the cover is the pulsar map previously sent ... | [
"source of the signal was a good location to find us? ",
"hell, thats how SETI works"
] | [
"We found one of those the other day drifting through the nullzone. Zorblax tractor beamed it in. He said it was some kind of 2-for-1 free lunch offer. We're going next week."
] |
[
"How does a GPS satellite track multiple targets at once?"
] | [
false
] | null | [
"GPS satellites don't track anything, they just broadcast radio signals that receivers will use to calculate their positions. You can sort of think of them like lighthouses."
] | [
"Ok. So they broadcast a radio signal, and phones pick up that signal. Now don't phones have to send that signal back to the satellites?"
] | [
"They don't.",
"GPS is like a radio station. They satellites broadcast their position and a very precise timing signal. The phone receive that signal from multiple satellites and calculate its position."
] |
[
"Is it possible for photons to interact with each other? And how would we know if they did?"
] | [
false
] | I was thinking about how many photons there must be whizzing around in space. It seems like empty space must be thick with photons from all the stars we can see in the sky. Surely they must cross paths from time to time? Then I wondered if these photons could interact with one another, and if so, how would they be affe... | [
"Yes, but it doesn't really happen except at extremely high energies. It is basically mediated through spontaneous creation of electron-positron pairs. There's a ",
"wikipedia page",
" on it, but it's not very good."
] | [
"Photons do interact with each other at the quantum-mechanical level (that is, EM waves don't interact with each other at all in classical E&M, but there is a very small probability in quantum electrodynamics).",
"One way is 'inelastic' scattering, where two photons collide and become an electron-positron pair; t... | [
"This is almost right; the more usual picture is that electrons exchange virtual photons, meaning one electron 'throws' it (thereby being pushed away) and the other 'catches' it (thereby being pushed backwards), creating a repulsion. This is an okay picture because it explains how photons can carry a repulsive elec... |
[
"Let's assume we can identify the basic building blocks of matter, and energy. Assuming infinite computer resources, could we re-create the past perfectly, virtually?"
] | [
false
] | [deleted] | [
"nope. we have to pick every single time. We can either know where a particle is very well or how fast it was going. Never both.",
"Here's",
" a thread from earlier today that explains why in more detail",
"edit: This question often gets asked the other way around. If you had a computer of infinite precision,... | [
"The first post in that thread is the best explanation. We've come to realize that it is an inherent property of the universe, and not \"just\" a tool problem. Every experiment you could possibly do will result in the same answer. We just don't \"know\" both simultaneously."
] | [
"What you are thinking about is exactly determinism as described by Laplace: ",
"http://en.wikipedia.org/wiki/Laplace's_demon",
"\nThe problem is that quantum physics is believed to be probabilistic and not deterministic: if you know perfectly the quantum state of a system you can only describe the possible evo... |
[
"How many frames per second humans need to perceive life-like fluid motion (in movies, video games etc.)? What is the maximum amount of frames we can process in a second?"
] | [
false
] | [deleted] | [
"it's not really a myth - in central vision, temporal frequency sensitivity bottoms out a little past 30Hz. in the periphery (outside of central vision), this 'flicker threshold' drops, so humans can pick up flicker as fast as 50-60Hz, but it has to have very high amplitude, e.g. alternation between black and white... | [
"How it isn't a myth if people can see the difference between 30, 60 and 120fps/Hz? I have done some experiments with my monitor and can certainly tell the difference, even between 100Hz and 144Hz, just by looking how smoothly my cursor moves.",
"I don't know if you fully understood my question (or my intentions ... | [
"Are you sure you're not confusing frames per second in a game with the refreshrate of your screen? Because those are very different, but somewhat related things."
] |
[
"Why is C-13 stable and not undergoing radioactive decay?"
] | [
false
] | I'm confused as to why certain naturally occurring isotopes are stable and not undergoing radioactive decay even though the ratio of neutrons to protons is not not 1:1. | [
"Well, the mass defect for ",
"13",
"13",
"13",
"B but that has a mass defect of ~16 MeV, so either case is adding mass rather than reducing it, so radioactive decay can't go.",
"If I'm not mistaken (and I may be) it's the relative stability of ",
"12",
"13",
"C still fairly stable.",
"Edit:",
"... | [
"This relates to how neutrons insulate charge within an atom. I'll be the first to say I don't know all there is to know about this, but protons, being positively charged want to repel from each other, and when they are able to repel the result is radioactive decay. Neutrons help to insulate this positive charge to... | [
"Can we get an edit on your comment. Having a little trouble reading it. Thanks"
] |
[
"Why don’t bacteria evolve resistance to soaps like they do to antibiotics?"
] | [
false
] | null | [
"Because soap works by stripping oils from the skin and binding to fats and proteins. To evolve, bacteria would have to get under the oil on your skin and not have any bindable surface... in which case it would cease to be bacteria.",
"Resistance to antibiotics is easier because the bacteria just has to modify a... | [
"soaps work by binding to things easily because of its chemical chains, making the combination of soap, water to distribute it and also bind somewhat, and scrubbing an effective way to remove bacteria from your hands.",
"Bacteria aren't necessarily harmed in the process unless the soap contains something intended... | [
"The trick with any antibiotic is to kill the bacteria without killing the humans cells next to it. so antibiotics needs to target specific enzymes, cell proteins, etc that only exist in the bacteria and not the human cell. But because their is a lot of similarities, the antibiotics has to be very specific, and as... |
[
"If you were trapped on an island with only sea water how would you hydrate yourself?"
] | [
false
] | null | [
"Straight distilled water has very few electrolytes, since salts never actually evaporate, they just sit at the bottom. Just as plants crave electrolytes, so does the human body. A severe lack of salts in the body can contribute to muscular problems."
] | [
"Well, you could of course take the water, evatorate it, collect the distilled water, remix it with a bit of seawater and drink it.",
"EDIT: I just read that you could probable drink the destilled water withour remixing it with seawater, provided you eat enough, so the water gets mixed with minerals again, so you... | [
"Fish blood/eyes are apparently a good source of water if you're trapped at sea."
] |
[
"why do media plates (agar, lb) have to be warmed up before use?"
] | [
false
] | null | [
"That's not standard practice, as far as I know. I have never heated up plates for simple cloning or repicking bacteria. But for growth analysis (or if you are working with something sensitive to temperature) you may want the cells to be at the correct temperature as soon as they touch the new media."
] | [
"Many “official” protocols (e.g. included with a product) will say something like “refrigerated plates should be warmed to room temperature before use”; but this is one of those steps that people quickly figure out is not important"
] | [
"This is the most common reason I'm familiar with. ",
"Streaking liquid culture into a specific pattern of quadrants is valuable for ensuring they are spread apart sufficiently to give you single colonies to pluck (growths that occur from one single bacterium), for example when you're trying to isolate one partic... |
[
"What shape are the nuclei of each element?"
] | [
false
] | I'd heard the protons & neutrons were in a ball shape for most of the periodic table, but that later periods they started to look less like spheres and more like footballs (american). I'm thinking specifically how the protons & neutrons arrange themselves, if it's in basically a ball or what. I looked online and only f... | [
"Most nuclei are not spherical in the ground state. The leading-order deviation in their shape that’s not strongly suppressed by symmetries is the electric quadrupole moment.",
"Most nuclei have nonzero quadrupole moments (specifically the Q",
" component of the quadrupole tensor, where z is the direction of th... | [
"So they’re not perfect spheres, but they are still not octahedral shapes like the images on google?",
"If you link a specific image, I can tell you whether it's realistic. But most nuclei are well-described as slightly oblate or prolate spheroids.",
"so are there any resources that can help me look into this m... | [
"So they’re not perfect spheres, but they are still not octahedral shapes like the images on google?",
"Btw: I’m just a hobbyist who is taking courses (aced chemistry 11 recently but I’ve got a way to go), so are there any resources that can help me look into this more deeply but are still accessible?"
] |
[
"Do photons ever interact with each other?"
] | [
false
] | Now, I'm thankful that at day-to-day energies, they don't. Otherwise, I wouldn't have cell phones or radio or sattelite television, amongst other useful things. But does the electromagnetic field ever interact with itself at very high energies? Or does its behavior stay essentially the same well into 'new physics' ener... | [
"No... you can still talk about the photon as a definite linear combination of the W and B bosons. ",
"Photons can interact with each other at the one-loop level by pair producing electrons and positrons which interact with each other. In this way and other higher order interactions, photons can scatter off each ... | [
"Photons are what we call abelian gauge bosons due to this there are no self interaction terms. You can do weird things like what omg is talking about, but we say its a non self interacting boson. There are gauge bosons that do interact with themselves, gluons. Its this self interaction that causes the weird behavi... | [
"Well in the electroweak interaction it doesn't make sense to talk about a photon anymore. When the symmetry breaking happens you transition from three weak isospin w bosons and a weak hypercharge b boson to the two w bosons in the weak force and a mixing of one of the isospin bosons and the b into the photon and t... |
[
"Why do rivers like the Nile and Amazon not form large canyons like the Colorado river did with the Grand Canyon?"
] | [
false
] | Are they just newer than the Colorado river? Or is the ground underneath the rivers not as conducive to erosion? | [
"Deep canyons tend to form where the land is in a state of slow, steady uplift where a river runs through it. So it's not so much that the water drills down into the earth, rather the earth is rising up around an existing river."
] | [
"I'm not familiar with the geology around the Amazon and Nile Rivers, but I do know that uplift of the Colorado Plateau is the primary factor in the formation of the Grand Canyon. As uplift occurred, the river sped up and was better able to cut through the rock."
] | [
"This is spot on. The Grand Canyon is so deep because land has been uplifted while the river cuts down through it. It's called an entrenched meander."
] |
[
"Is there an argument for a trigonometric function which results in a rational number, other than \"rational multiples\" of pi?"
] | [
false
] | sin(2), cos(3), sin(√2) are irrational. Yet, sin(π/2) = 1, sin(π/6) = 1/2 [rational numbers] Is there any argument x, which cannot be expressed as a rational*pi, that would be make sin(x) a rational number? | [
" Yes: lots of them (I initially mistakenly read your question the opposite way). Namely, let's start with the following result:",
": The only rational numbers x in [0, 1/2] such that sin(xπ) is rational are 0, 1/6, and 1/2.",
"The proof is somewhat involved and requires a bit of external math background I woul... | [
"It seems like the bottom line is correct, but it seems like that theorem still leaves open some possibilities. For example, take sin(1). 1 satisfies op's condition because it is not a rational*π, but it also is not ruled out by what you say because 1=(1/π)π, and (1/π) is irrational, so maybe (1/π) is the irrationa... | [
"Whoops. I thought OP was asking the opposite of what he/she really did. I corrected the initial post. Thanks!"
] |
[
"What distance does Earth travel through space in a year, relative to the universe?"
] | [
false
] | null | [
"There is no \"relative to the universe,\" as there are no inertial reference frames. In the reference frame of the Earth's center, it doesn't move at all, in the reference frame of the sun, it moves about 300 million miles, in the reference frame of a neutrino it moves almost a light year."
] | [
"The big bang was ",
", there is no center. There is a reference frame in which the cosmic microwave background is most symmetric, and we are moving about 650 km/s relative to that."
] | [
"But aren't we expanding outward from the Big Bang? Is there no measurable way to tell how fast our galaxy is moving?"
] |
[
"what happens to the Carbon-14 that decays inside of us?"
] | [
false
] | i know it decays into nitrogen, but my carbon is doing stuff, like making up my cells. what happens when all of a sudden the carbon in those molecules turns into nitrogen? does this have any meaningful impact on our biology? is it so rare that it's negligible, or what? | [
"It pretty much does what you think it might. It changes into nitrogen which changes its chemical properties. Since Carbon typically makes 4 bonds while Nitrogen prefers 3 if the bonds aren't destroyed by the nuclear reaction itself (Since these reactions can often give off a fairly large amount of energy) they'l... | [
"I believe your intuition/estimation about the number of decay events per lifetime is off by quite a few orders of magnitude.",
"For an average person, a conservative estimate is that 2683.167 C-14 atoms in the body decay per second.",
"700,000,000,000,000,000,000,000,000 carbon atoms in the body.",
"C-14 is ... | [
"My estimates are not off. It's a very simple calculation",
"e",
" = %percent of the population remaining at time ",
"Therefore if you obtain k by using the half-life and substitute t=100 years, you get an answer of 98.8% or that between 1-2% of the C-14 that was around when you were born will have decayed w... |
[
"Shouldn't we be looking for fossils on Mars rather than life on Mars?"
] | [
false
] | Every article I come across about the search for water and life on Mars seems to point to the fact that conditions were once much better for life on the planet quite some time ago. Rather than scour a (mostly) dead planet, shouldn't we be digging under the surface of these lake and ocean beds to search for fossil recor... | [
"The fossils we'd be looking for on Mars (at least for now) would be ",
"microfossils",
". Instead of really obvious bones or nautilus shapes in stone, we'd have to find the tiniest, microscopic impressions left behind by bacteria and other small organisms.",
"The current rover lacks the ability to do microsc... | [
"That's exactly what Curiosity, and eventually the ExoMars rover, is/will be doing.",
"Just they're not looking for fossils in the sense you mean. Instead they're looking for \"fossilised\" chemical signs of life - leftover organics that may have been produced in the past and left in place. One of the problems is... | [
"Pretty cool how the original rover was only designed to last certain kilometres but its been going strong almost a decade. Makes me wonder about the new one.",
"Water on mars was once fresh but is now vinegary sour right? Makes me wonder if mars is the equivalent to an abandoned building of the solar system. Tha... |
[
"What metrics are there for expressing the quality of a series of pseudorandom numbers?"
] | [
false
] | How can I quantify "how random" a set of numbers is? | [
"Kolmogorov complexity",
" is an important one. The Kolmogorov complexity of a string is the length of the shortest program that can generate that string.",
"Note that given any string, say \"This is a sentence\", you can write the following program:",
"echo \"This is a sentence\";\n",
"Thus the Kolmogorov ... | [
"There are also some statistical tests to determine if a pseudo random number generator is good. See ",
"here",
" or ",
"here",
" depending on how much detail you want."
] | [
"Thank you."
] |
[
"Is DNA stable in a vacuum?"
] | [
false
] | null | [
"Under dehydrating conditions, DNA will turn into one of the three stable DNA forms, in this case, ",
"A-DNA",
". A-DNA is similar to the common form, B-DNA, as it is right-handed, but it is a little bit more compacted (scrunched) than B-DNA. The third form of DNA is Z-DNA, which is a left-handed helix. As f... | [
"A vacuum is empty of matter, however that does not mean it is empty of electromagnetic radiation. If you have a vacuum enclosed in a transparent box, you could irradiate it with infrared radiation. Any particle within that box (in our case the DNA) would be bombarded with the IR radiation and would in turn heat up... | [
"The ",
"hydrolysis of a phosphodiester bond",
" is catalyzed by any acid or base. Even at neutral pH, there is a small concentration of H+ and OH-. However, these species must interact with the bond with sufficient energy for the reaction to happen. At -80C the crystalline lattice of the H20 prevents the movem... |
[
"How long does a mirror image reflect itself in two opposite mirrors?"
] | [
false
] | I am aware that many conditions must be set first: 1) "Long" can be expressed in distance, time or number of reflections; 2) There can be more mirrors for better observation conditions, maybe a closed triangle. 3) The mirrors are of course positioned in such a way that an object (say a red ball) is reflected back and f... | [
"Your average mirror might have a reflectivity of 90%. A really, really good mirror might get you 99%. This means, for any given photon there is a 99% chance that it survives the bounce on the mirror, and continues to be part of the image. There is a 1% chance it is absorbed/scattered.",
"So, assuming that we are... | [
"There are two limiting factors here.",
"The first, imperfectly reflectivity, seladore covered in detail.",
"The other is resolving power. As an object gets smaller in a mirror, interference patterns due to the wave nature of light start build up until the image is no longer recognizable.",
"Assume we have t... | [
"No mirrors are perfect reflectors. They absorb some of the photons and heat up a tiny bit each time the image bounces off of the mirror. Eventually there is no light left as it has all been converted into heat."
] |
[
"What, if any, known life could survive on Mars without the aid of a suit or highly controlled environment?"
] | [
false
] | Plant, insect, bacteria? Furthermore, (Bonus Question) if we were to attempt to make Mars habitable what type of life would we try to introduce to Mars? | [
"Indeed, which is why considerable precautions are taken to sterilise all craft sent to Mars."
] | [
"There are populations of bacteria within the Earths crust, several km below the surface. I see no reason why such critters would be unable to deal with conditions in an equivalent setting on Mars, especially in a more geologically active zone such as one of the volcanic centers or perhaps Valles Marineris."
] | [
"So even if there is no life on Mars today, humans could very well \"contaminate\" Mars with life, if we decided to?"
] |
[
"Why does the electron's charge stay constant even under relativistic velocities?"
] | [
false
] | After looking up the question on google it seems all experiments show that the charge of an electron is independent from its velocity. Is there a mathematical background or theory why this is the case? What would happen if it did change like mass does at relativistic velocities? | [
"Electric charge is a relativistic invariant. The electron has a four-current density",
"J",
" = (ρc,",
"),",
"where ",
" is the three-current density.",
"The electric charge of the particle is simple the integral of the charge density over space:",
"Q = ∫ ρ(",
") d",
"r, over all space.",
"But ... | [
"What would happen if it did change like mass does at relativistic velocities?",
"The notion that the mass of a system changes as it approaches relativistic velocities is anachronistic. The concept of \"relativistic mass\" is very unpopular these days, because while it makes a very few small things simpler (like ... | [
"Is that how you would define electric charge from first principles? Does that not beg the question: how do you define charge density?",
"I would just say that the charge of a particle is defined to be that number ",
" such that dp",
"/dt = qF",
"U",
". Classical electromagnetism is the unique linear Lore... |
[
"Can mountains disrupt the paths of hurricanes?"
] | [
false
] | Hello , I know that mountains can create a rain shadow making the area down wind of the mountain very dry. I was curious if you had a mountain range would it disrupt the hurricane and possibly break it up? Or would the hurricane just roll over the mountains like very little was there? With my very very basic understand... | [
"Yes, you would be correct. Land essentially suffocates hurricanes. Mountains, because they are large, choke the moisture out of the hurricane rather quickly and stop the circulation. Depending on the size of the hurricane and size of the mountain, the hurricane could reform if it were to interact with warm water a... | [
"A quick search shows the mass of mt. Everest estimated at 357,000,000,000,000 lbs. (357 trillion lbs). if I can buy gravel delivered from the quarry for $15 a ton, and figuring that the mass of Everest would be enough to build a whole range of regular mountains, I'm guessing building a mountain range on the gulf c... | [
"You're forgetting that you have to source all that gravel, so if you start running out from suppliers and you have more demand than supply the price starts to go up as well."
] |
[
"How is the infrastructure of the internet built?"
] | [
false
] | I understand some basic concepts, such that there are servers that users request information from, or upload information to, but how is it all physically organized? Are there central hubs that everything goes through? How is a connection established between one computer another for that information to be exchanged? How... | [
"The \"internet\" is simply a huge network. There are many subnetworks, and subnetworks of those networks, but it all is just a big web of connections. ",
"Some huge telecommunication companies own huge fiber optic cable trunks, and they have an agreement to connect them. The top level ISPs are called Tier 1 ISPs... | [
"Somehow you completely failed to explain the notion of \"routers\", which is quite odd given how central they are to workings of the internet. Routers are specialized computers that have multiple (or many) connection leading to them and on every packet they receive they decide where to send it (ie. which of the ma... | [
"The general infrastructure can be observed if you simplify it - take a look at the old Arpanet infrastructure. It's internet simplified to a very very simple level - its earliest incarnation. ",
"http://en.wikipedia.org/wiki/ARPANET",
"By looking at historical internet, you'll also be able to get an idea of ... |
[
"Everybody knows in physics it's theoretically possible to walk through a wall. What other theoretical quirks are there?"
] | [
false
] | null | [
"That, according to some physicists here, the \"force\" of gravity is but a mere optical illusion. It gives me ths impression that we're all a stop-motion movie. ",
"And the fact that when you approach a black hole the physics can conspire such that the black hole becomes in \"front\" of you time. That this is du... | [
"It is theoretically possible that heat will flow from a colder object to a hotter one, so putting some ice in a glass of warm water could freeze the whole glass of water. It's possible but extremely unlikely. Quite like the tunneling you describe."
] | [
"I know what you're saying, but you've got to elaborate!"
] |
[
"What is the smallest particle our skin can feel?"
] | [
false
] | So I was walking on a cloudy day and I noticed that before raining, most of the times, I feel the slightest amount of water. This is so tiny I cannot see it, but my skin does sense it. What would be the smallest quantity of atoms our epidermis can feel? Note: I have a general understanding that our skin has different s... | [
"Being able to feel something in the order of 10 nanometers is more or less something like this: Imagine you had an perfectly smooth surface (so the irregularities are smaller than those 10 nm). Using this surface as a drill ground for bacteria, you are able to tell whether the bacteria are there or not, assuming t... | [
"According to ",
"this article",
" humans can sense the difference between surfaces that are 13 nanometers in amplitude variance."
] | [
"According to ",
"this article",
" humans can sense the difference between surfaces that are 13 nanometers in amplitude variance."
] |
[
"How do lakes deep underground maintain an ecosystem with no energy input from the Sun?"
] | [
false
] | null | [
"Underground aquifers could support primitive microbial life-forms if they were adapted to living off the minerals, and hydrogen seeping into the water from the surrounding rock. They may also adapt similarly to deep sea life that lives off of/near hydrothermal vents if they're present in the underground aquifer"
] | [
"Any chemical can serve as an energy source if there is a more thermodynamically-stable energy state, such as glucose being oxidized to carbon dioxide and water. Both of those are more stable than glucose and the oxidation of glucose into them produces energy.",
"There are many such compounds such as methane, dec... | [
"Yes and no. Mostly no. When talking about energy sources for life you are talking about some high energy molecule that you are breaking into lower energy molecules and using the energy difference to power the chemical reactions of life.",
"For most terrestrial vertibrates it is glucose or some other form of suga... |
[
"How large is the possibility of life on Mars?"
] | [
false
] | null | [
"We don't know. We only have one instance of life to base our assumptions on. It's all educated speculation, but what we really want is confirmation one way or the other. ",
"If we find life did exist, but no longer appears common it'll tell us things. ",
"If we find life did exist and is still common, it'll te... | [
"That is anybodys guess at this point. What we know is, that when we look at really hostile environments here on earth, we almost always find life because it is highly adaptable. This means, that if life did indeed evolve on Mars, chances are that it's still there in one form or another. But that is just a qualifie... | [
"Mars used to be Earth but got lost in the turnstile of planetary fate. Yes there is life on Mars however it is a tad different from what we call \"Normal\". Water exists as do small biological, things, if you will. There is life on many yet unexplored planets we just have to get our shit together and go looking fo... |
[
"How did water form or arrive on Earth and how did such large quantities form?"
] | [
false
] | null | [
"Meteorites are solid pieces of space debris, mostly stony, a fraction of them iron meteorites. I guess you're thinking about comets.",
"There are 1.332 billion cubic kilometers (326 million cubic miles) of water on earth, and that takes a pretty improbable amount of comets (for comparison, the whole Oort cloud ... | [
"Delivery by comets does not work as the ",
"deuterium to hydrogen ratio for the comets is twice that of the earth's oceans",
", ruling them out as major contributors of earth's water. The going idea is instead that accretion of planetesimals (you get into a very strange nomenclature of different sized and comp... | [
"that takes a pretty improbable amount of comets",
"Not at all improbable. Remember, Earth itself is made entirely of asteroids and comets. There were a lot more of them when the Solar System was forming. The asteroids and comets we see today are only the crumbs left over after the rest went into forming the plan... |
[
"Is there some force that counters a particle that approaches light speed?"
] | [
false
] | This may be ignorant but, if you apply a constant electromagnetic force on an electron in, say, the LHC, what keeps the electron’s speed from increasing to infinity? Does a force start countering the electron? | [
"Just for the record, the LHC is a ",
" collider, so it's not designed to handle electron beams.",
"But anyway, when a charged particle accelerates, it loses energy to radiation. But that effect is only significant at very high Lorentz factors (E/mc",
"), and when the trajectory of the particle is curved. Thi... | [
"The energy of a free particle with nonzero mass is E = mc",
"/sqrt(1 - (v/c)",
"), and the momentum is p = mv/sqrt(1 - (v/c)",
").",
"Take the limit as v goes to c."
] | [
"What RobusEtCeleritas said is true. Just to add a little bit, here is a link that explains how velocities work in special relativity:",
"http://hyperphysics.phy-astr.gsu.edu/hbase/Relativ/veltran.html",
"Edit:",
"To calculate the velocity of any massive particle, you can determine the gamma factor, which is ... |
[
"Evolution and Libido"
] | [
false
] | Dear AskScience, I've done a reddit and google search but I'm unsure as to what the evolutionary significance is behind women's libidos apparently peaking at 30 or 40 and men at a significantly younger age? Is this information actually correct? I seem to recall in sex education classes when I was back in school, that s... | [
"I have also heard the claim that the female libido peaks at 30-40, but is that claim supported by studies?",
"edit: Seriously, asking for sources in AskScience results in downvotes?"
] | [
"women's libidos apparently peaking at 30 or 40 and men at a significantly younger age? Is this information actually correct?",
"I've heard this claim many times but never seen a single solid peer-reviewed study to back this up.",
"I think it's as false as the societal expectation that men always want sex witho... | [
"The easiest evolutionary reason for males having a larger libido in general, is that it's best for men to impregnate as many women as possible, because the biological cost to produce a teaspoon of sperm & semen is very low.",
"Women should have a lower libido in general because they should wait around for a high... |
[
"Nuclear reactors produce radioactive waste right? And those reactors use the processes that take place in the sun. So what happens to the nuclear waste that is produced by the sun?"
] | [
false
] | null | [
"The kinds of reactions in a fission reactor are completely different than the ones happening in the sun."
] | [
"Oops. Well fusion reactions still produce waste right? What happens to that?"
] | [
"The waste from the reactions in the sun is mostly just helium-4.",
"For a general star, depending on how it ends its life, it may eject its \"waste\" into the surrounding space or just quietly collapse and dim out. ",
"Your body is made of the \"waste\" from stars which have gone supernova in the past."
] |
[
"Where does a scientist obtain a positron?"
] | [
false
] | [deleted] | [
"Positrons are actually fairly easy to get a hold of. There are many naturally occurring unstable isotopes that decay via positive beta decay (carbon, potassium, iodine...). The decay products of these isotopes are a positron (which we can collect) and a neutrino (which completely escapes).",
"Anti-protons are ... | [
"There's a specific nuclear reaction that produces one electron and one positron when it happens (gamma ray collision with a charged obstacle, an atomic core for example).\nIf electric and magnetic fields are applied, it's possible to separate them before they annihilate each other."
] | [
"Go to the hospital and fake the symptoms of a lung tumour, and they might order a PET scan. When they give you the contrast agent (a form of sugar), you will temporarily be a positron producing person."
] |
[
"So I'm pretty much running the science club as school...help!"
] | [
false
] | null | [
"This isn't ",
"r/atheism",
"! Take that out of your title and I will consider approving this."
] | [
"Whoops! I'm sorry! I figured this subreddit would be the best to post after I had posted in ",
"r/atheism",
". My bad. "
] | [
"Yes, but you called us r /atheism"
] |
[
"What is the name of this counterpoint of force?"
] | [
false
] | null | [
"Escape velocity",
" is the speed needed to escape some potential with not further force being applied. A rock can leave you hand at any speed.",
"If you throw a rock you stop applying a force to it as soon as it is no longer in contact with your hand.",
"If the rock is tied to a string you are holding then a... | [
"Maybe not so much the string. But the principle in which a satellite has to maintain an orbit so as to not leave earth's orbit or fall back into it. That perfect point. What's that called?"
] | [
"An equilibrium?"
] |
[
"Hey r/Askscience, I recently learned that our moon Is slowly moving/ drifting out of Earth's orbit. When the moon reaches the point where it no longer affects our tides, what will happen to Earth's oceans?"
] | [
false
] | [deleted] | [
"It will always have small tidal effects on Earth's oceans, but no more so than the Sun. \nNothing much will really happen to the oceans, they'll just stop oscillating up and down with the high amplitude that they do today. "
] | [
"So does that mean all the Hollywood moon crisis is garbage? Like could there be a moon apocalypse? "
] | [
"I don't know exactly what you're referring to by a moon crisis but I'm going to assume it is in fact garbage."
] |
[
"Why can the same temperature in different rooms feel completely different?"
] | [
false
] | I work in a freezer and chiller at work. We have two freezer units, both running approximately -24 Deg C. But one of them feels significantly colder than the other despite the temperature being within 1 deg C of each other. What is causing my body to feel a difference between these two rooms? Humidity? Or is there more... | [
"It could be a few things. You mentioned humidity. There is a lot of energy in water vapor and this can account for some of the difference felt. You should also look at where the air is coming out. If one freezer has air blowing toward the back but the other has it blowing at the door when you walk in, you will f... | [
"Regarding being outside, it is almost certainly wind chill factor."
] | [
"A lot of our perception of temperature is relative. For example, have you ever gone into an air conditioned building after being outside on a hot day and been too cold, only to stay in the room for a while and start to feel hot again? Maybe the rooms that lead to the different freezers are different temperatures... |
[
"Why is it impossible for an object to have an absolute velocity of 0?"
] | [
false
] | null | [
"How would you like to define absolute velocity? Which frame of reference are you choosing to be your absolute reference frame for measuring speeds, and why is that frame of reference preferred rather than any other frame you could choose?",
"In short, Special Relativity states that there simply isn't any preferr... | [
"because no such thing as absolute velocity exists.",
"if an object is at rest in one frame of reference, then you can easily give another frame of reference where it moves constantly with v = 0.5c in some direction. since no preferred or absolute reference frame exists, these frames are equally good."
] | [
"Any massless particle always moves at c in a vacuum, according to special relativity."
] |
[
"Why are there so many wildfires in California?"
] | [
false
] | Edit: Thank you to everyone for thoroughly explaining :) upvoted all of your answers.I now have a better understanding. From outside the US it seemed a bit weird since we hear so much about California yet there are so many wildfires. | [
"Simply, it is very dry there. ",
"Much of California is covered in dry grass. It often will not rain in large parts of California for months at a time. ",
"Combine lack of rain with high temperatures and plenty of fuel and you get large quick growing wildfires.",
"Rainfall stats in California",
"Compared ... | [
"I’m not saying you guys never get wild fires, but this year so far you have had 9000 acres burn; while California has had 432,000 acres burn. ",
"To be fair, California is already a lot bigger than the UK, but it has still had nearly 50 times as much land burn."
] | [
"CA gets rain and snow in the winter, then dries out for months at a time in the summer. This provides enough moisture for plants to grow, then dries the area out enough for the plants to burn."
] |
[
"Are genes from Mom/Dad just a coin flip at every \"zip\" of the DNA sequence? How far away can we deviate from 50/50?"
] | [
false
] | People often say we are "50% of Mom, 50% of Dad", wouldn't we actually be some amount above/below, like maybe I'm 45/55 and my sister would be 57/43, my brother maybe 49/51, etc? I assume there is some point like 30/70 which cannot be achieved, do we know of such a point existing (are we all a minimum of 40% one parent... | [
"You contain 50/50 from your mom and dad. It's essentially a coin flip at each of their genes, which you got: your dad might an allele for brown eyes and an allele for blue eyes, and you are guaranteed to have received one or the other from him. Same as with your mom. But 50% of your genome came from each.",
"Wha... | [
"You contain 50/50 from your mom and dad.",
"Technically it is possible for you to receive more or less from either though:",
"https://en.wikipedia.org/wiki/Aneuploidy"
] | [
"Pffff, as you note, that's totally wrong.",
"You inherit chromosomes, not genes per se. So the number that is relevant for variability is 23, not 10000. That's a lot more variance.",
"And there's also the fact that recombination will almost always happen, so you're pretty much guaranteed to inherit some of eac... |
[
"Iron smelting requires extremely high temperatures for an extended period before you get any results; how was it discovered?"
] | [
false
] | I was watching a documentary last night on traditional African iron smelting from scratch; it required days of effort and carefully-prepared materials to barely refine a small lump of iron. This doesn't seem like a process that could be stumbled upon by accident; would even small amounts of ore melt outside of a furnac... | [
"Well, people had thousands of years of bronze smelting before anyone figure out how to get iron from ore. People used meteoritic iron long before then too, but of course there wasn't much of that.",
"Iron isn't too hard to get out of ",
"bog ore",
" or ",
"goethite",
". Some places where you could get bo... | [
"Add to this that in 10,000+ years, humans haven't gotten any smarter. We've been this smart. We just have way more access to knowledge and the ability to pass it on through language, writing, and developing civilization. People still expiremented and were able to learn just as now. It's not a giant leap to discov... | [
"Why do you find that unusual at all? That's an extremely predictable and easily understandable misconception. People commonly equate intelligence and knowledge. Whether or not that's actually true is irrelevant, but it's not even remotely surprising or \"unusual\" that people use the two interchangeably."
] |
[
"Appilications for Diffusion (Cell, Biology) in industry?"
] | [
false
] | Hi Reddit, I recently started my first year on a foundation degree in Biotechnology. Our First assignment is to create a powerpoint explaning a Cell transport method, give examples and show how its used in industry. My topic is Diffusion. I have the first bit covered, now I'm finding it hard to find how Diffusion is u... | [
"In microfluidics and other highly laminar flow processes, mixing can only be accomplished through diffusion."
] | [
"That's great thanks"
] | [
"Dialysis",
" in protein purification."
] |
[
"To Linguists: Listen to the difference between American English and British English... and that is only after 250 years separation. Is it true that the \"Southern American\" dialect sounds more \"British\" (with respect to the current dialect 250 years ago) than the current English dialects do?"
] | [
false
] | I'd heard that the Tangier Island dialect is probably the closest we can come to hearing how English sounded right before the Revolutionary War (due to isolation), and that dialect sounds like a particularly heavy southern drawl compared to the "Queen's English". Any linguists have insight into this? | [
"Is it true that the \"Southern American\" dialect sounds more \"British\" (with respect to the current dialect 250 years ago)",
"I'm not sure I understand your question fully, but I think you're operating under a false assumption, which is that any language/dialect remains static over time with respect to sound ... | [
"I'm not sure what you are talking about or asking here, could you clarify? What I can tell you is that British English in 'past times' sounded a lot like the Northern dialects of English (such as Yorkshire, Lancashire, etc.) and other English dialects that remained vaguely unchanged through the ",
"Great Vowel ... | [
"I'm not sure I understand your question fully, but I think you're operating under a false assumption, which is that any language/dialect remains static over time with respect to sound patterns. ",
"I'm pretty sure the questioner is not operating under that assumption. Quite the contrary, they are curious about w... |
[
"Is it possible to deflect or reflect back infrasound waves?"
] | [
false
] | [deleted] | [
"Ear muffs would work a treat. Infrasound isn't really weaponisable. If it was it would be the mechanical energy of the shock-waves that would be the effector. You may as well just use a hand grenade if you want to make a big shock-wave. The LRADs are just incredibly loud, so loud they cause extreme pain, incapa... | [
"I would think that any sound deadening insulation would work as would anything stiff enough to stop the air movement",
"Just out of curiosity, why do you feel you need to do that?"
] | [
"Lrads not infrasound, ",
"http://en.wikipedia.org/wiki/Long_Range_Acoustic_Device"
] |
[
"Can the gravitational center of an orbit exist outside both orbiting bodies?"
] | [
false
] | [deleted] | [
"Yes, this is called a barycentre. Pluto and Charon are examples of a binary system orbiting about a common barycentre."
] | [
"A crazier example: Jupiter and Sun. ",
"http://spaceplace.nasa.gov/barycenter/en/barycenter.en.gif"
] | [
"This is a gif",
" of a binary system in which the barycenter lies outside both masses, and the orbits resemble that of the Pluto-Charon system.",
"This is also a gif",
" of a binary system in which the barycenter is outside both masses, but the orbits are both elliptic and actually cross each other."
] |
[
"Will the lighting in a room change when the area of it is increased, even slightly?"
] | [
false
] | Say you are in your kitchen for example and you open a cabinet: does the room become less bright because the light is now dispersed more or does it say the same? Why? | [
"Yes, it gets dimmer, very slightly, assuming the new area is of the same reflectivity as the rest of the room, for the exact reason in your question. ",
"Imagine sitting on a couch in a room one overhead light and expanding walls. As the room expands, the light has more surface to reflect to and scatter and the ... | [
"Thanks! Good answer!"
] | [
"As the room expands, the light has more surface to reflect to and scatter and the room will get dimmer and dimmer.",
"On the other hand, there's also more surface area to scatter the light to your eye. I can imagine this might cancel out in some cases"
] |
[
"Given our position and trajectory around the sun, what kind of extremes and temperatures would we experience without the aid of atmosphere and the magnetic field, how would it compare to other rocky worlds without these things?"
] | [
false
] | Title is rather descriptive and I think it does the question justice. Any informed answers are greatly appreciated. I think answering this question would greatly increase one's appreciation for the worldly forces we have, and would offer a unique perspective on where we are within our solar system. | [
"Well, we happen to have a pretty good analogue to this, and that's Mars. So if we were to lose the magnetic field, that would mean the planet's core has cooled down enough it has solidified (or mostly solidified) so there would be less frequent volcanic eruptions and other geologic activity. ",
"The next mission... | [
"My question is more of a comparison to mars. I know a world such as ours, without our \"shields\" in place, would be much like mars. I figured that if we are some millions of miles closer to the sun, our barren landscape would have extremes of our own, that would be different from the extremes of mars, or planets ... | [
"Interesting, would of never equated the pure mass of our planet to the function and density of a hypothetically thin atmosphere like mars. Truly unfortunate for mars. More questions arise with this however, such as these scenarios applied to planets bigger than Earth. But yes, that answers the question fully, than... |
[
"Why do we feel nauseous after getting hit in the head?"
] | [
false
] | [deleted] | [
"Nausea can happen when an expanding lesion in the upper brain like subdural hematoma or swelling from concussion forces the brain down into the skull opening, the foramen magnum. That lower part of the brain (brain stem) contains nuclei for the vagus nerve, which controls many thoracic functions including vomiting... | [
"No, concussion and hematoma exert way more pressure than you should get from migraine dilating a branch of the middle cerebral artery. ",
"Elevated pressure in the cerebrospinal fluid pressure causes headaches, but migraine isn't usually associated with CSF elevation.",
"More likely migraine nausea is the symp... | [
"I have always wondered if this the same mechanism that causes migraine vomiting/nausea? The increased blood flow to the brain would basically cause the same swelling as a concussion, right?"
] |
[
"Help in choosing a career path?"
] | [
false
] | Hey scientists of reddit, I posted this on AskReddit too but I just discovered this place so I'll post here too if that's ok. So I am a science student interested in engineering, mostly because that's the only discipline I know that people tell me has career opportunities, but I do not know what branch to choose for my... | [
"You may want to look into:",
"\n",
"Bioengineering/Biomedical Engineering",
"\n",
"Bioinformatics",
"\n",
"Chemical Engineering",
"\n",
"Environmental Engineering",
" ",
"If you were looking for the most employable of those fields (assuming you got a bachelors degree in one of them), I'd have ... | [
"I'm into biology, careers are highly dependent on whether the democrats win or the republicans do :P",
"On a serious note though, I've seen my more tech-research-oriented friends get better and more job opportunities than my biology-research-ones.",
"Though some questions in biology are very profound, basic sc... | [
"You don't mention how old you are - but I'm presuming around 20 or so.",
"In addition to the earlier comments, it's worth noting that no matter what you feel about your career interests at your age, this may change drastically in the next 5-10 years. As such, my advice would be to go into something that is techn... |
[
"Why is it that when metal conductors are cooled they have lower resistance? Can you lower resistance by increasing pressure as well?"
] | [
false
] | What is going on at the molecular&/subatomic levels that makes this possible? Thanks! | [
"For a metal, reducing the temperature reduces the kinetic energy of the ions in the giant metallic lattice (hence they get colder). ",
"The ions in the lattice are always vibrating, and their vibration is directly proportional their kinetic energy. Therefore, as the temperature lowers the lattice vibrates less. ... | [
"I don't agree with your explanation of semiconductors. Their resistance decreases as temperature increases (or vice versa) because as the more thermally energetic it gets, the more electrons can be knocked up a band creating more conductive electron-hole pairs. And this effect increases at a greater rate than the ... | [
"No, superconduction involves the electrons pairing up, known as a \"cooper pair\". The electrons then cooperate to move through the material withuot resistance. Lots of weird quantum mechanics stuff. "
] |
[
"How are SMS sent/delivered over cellular networks? (HSPA and LTE)"
] | [
false
] | null | [
"That's correct, it goes over HSPA. When the phone displays LTE, it will also maintain an HSPA connection in the background for Voice Calls and SMS. SMS is sent very quickly in the signalling plane, so the LTE radio stays on (as there is no benefit to disabling it for the duration of the SMS send/receive), however ... | [
"So SMS in HSPA is sent via the circuit switched network, rather than the data network, using the signalling space. I'll let a CS engineer describe this, as I work in the IP domain.",
"LTE is actually a bit more complex, as it moves from a circuit switched, to a packet switched world. LTE itself doesn't have a co... | [
"That's interesting. Thanks. So if a carrier only uses LTE for data and falls back to UMTS / HSPA for voice calls, would SMS also go over the HSPA circuit switched network? My carrier doesn't have Voice over LTE. When I make or receive a phone call, my network indicator immediately drops to H from LTE and within 1 ... |
[
"Why don't other massive objects exude Hawking Radiation?"
] | [
false
] | I'm a chemistry/math student, not a physicist, so I don't get this. Unless I'm seriously misunderstanding something, wouldn't Hawking Radiation come off planets and other non-blackhole objects? And maybe it's not Hawking Radiation, maybe it's just particles tunneling out of the objects gravitational field. I've been ru... | [
"This is an excellent question. I've thought about it too, and although I lack any decent education in GR, QFT in curved spacetime, or Quantum Gravity, it seems to me that OP is right and all comments so far have been wrong.",
"Hawking radiation is ",
" caused by virtual particles popping in and out of existenc... | [
"Dcarrier is correct in that beyond the event horizon there is no path in spacetime that does not lead you closer to the singularity.",
"Saying that the escape velocity of a black hole is c is a good approximation for teaching at lower levels but doesn't actually describe the reason escaping past the event horizo... | [
"No it would not.",
"Yes it would. If you have enough thrust to counter gravity, it won't accelerate towards the black hole. Or you could thrust in the direction of your orbit and you don't even need a high acceleration to escape.",
"That doesn't work on black holes because they don't run on Newtonian physics. ... |
[
"When we look up at the milky way, what part are we looking at?"
] | [
false
] | Here is a picture from Michigan. (not mine) do we see an arm of it? Can we see the center? | [
"The ",
"center of the galaxy",
" is in the direction of the constellation Sagittarius. There's a bit too many stars for me to see which part of the sky this is, it's hard to pick out the significant constellations. "
] | [
"To start, ",
"this image",
" answers pretty well the question of just what part you're looking at. In short, the answer is different for (northern hemisphere) summer vs winter- in the summer you're looking towards the center, but during the winter you're looking out of the Milky Way. I should note though tha... | [
"Yeah, but you can at least catch a glimpse of the central bulge through ",
"Baade's Window",
", a small break in the interstellar dust clouds."
] |
[
"What is (theoretically) the oldest particle in the Universe?"
] | [
false
] | Is it possible for one single proton to be as old as our universe, or do they just not have that sort of life span? I just got out of a lecture where our professor invited an expert on the big bang, but I didn't quite know how to ask the question at the time. Thanks for any and all input :) | [
"In the first instants after the big bang, we think that different particles existed than do now thanks to ",
"grand unification",
". As the universe cooled that unification was broken, and around by 10",
" seconds after the big bang the fundamental particles we know now were created, and by about 10 seconds... | [
"Under the Standard Model the proton is stable. Certain theories predict that a proton can decay, however its lifetime is on the order of 10",
" years (if not larger, this is the lower bound). Note that the age of the universe is ~10",
" years."
] | [
"Well, a proton can not be as old as the universe, but it can be almost as old as the universe. ",
"The majority of protons we have now was created in the initial condensation of energy with some created after that through decay processes. "
] |
[
"Is magnetic field real?"
] | [
false
] | I've read many times that magnetic field is just electric field viewed in motion. (relativity + electrostatics) | [
"Photons aren't made of fields. That's a classical approximation of light which is descriptive under certain conditions, not an objective statement about the true, Platonic nature of reality.",
"And magnetic fields can't exist without any charge present. But there always is charge present. Charge exists in the un... | [
"So looking at this from a classical (non-quantum) perspective, electric and magnetic fields are all part of a larger structure called the ",
"Electromagnetic field tensor",
". Relative motion can cause the terms of that tensor to change. So I'd say it's somewhat fallacious to say that the magnetic field doesn'... | [
"Photoelectric effect, Compton scattering, pair production, spectroscopy. Et cetera."
] |
[
"Would heavy unstable elements at the core of a star have a significantly extended half-life due to gravity?"
] | [
false
] | null | [
"If you think of gravitational time dilation: No. It's a tiny effect for stars, just a few parts in a million. Instead of 1 second the lifetime (as seen from far away) is now 1.000005 seconds or something like that (with the exact number depending on the star) - not a big deal."
] | [
"Sure, but that only seems like a significant difference because of human time frames. Those 20,000 years describe the difference between being at ",
" half of the original mass, and ",
" half of the original mass."
] | [
"Well, there are neutron stars that are functionally one giant unstable element held together by gravity instead of the strong force. The only reason they don't collapse further is because of neutron degeneracy pressure. Considering the relationship between half life and atomic size, coupled with the longevity of n... |
[
"What kind of interaction ( what do they do/exchange) is happening between a nuclei and the electron cloud and what about the fact that this interaction has a probability to reasonably occur across infinite distances ?"
] | [
false
] | null | [
"It’s just a Coulomb interaction:",
"V(r) = kQq/r."
] | [
"Thank you providing the formula it's \"cute\" i was able to find it too, i found another cute one \"E=MC^2\" and more things like like 1+1=2. But What kind of interaction ? What do they exhange ? What is happenning ? And what about the fact that this interaction has a probability to reasonably occur across infin... | [
"But What kind of interaction ?",
"A Coulomb interaction, as I said above.",
"What do they exhange ?",
"If you want to think of it in this way, they exchange virtual photons.",
"What is happenning ?",
"I don’t know what you mean by this.",
"And what about the fact that this interaction has a probability... |
[
"why can't particles of zero mass be at the rest?"
] | [
false
] | in a book I'm reading it says why is that? | [
"Special relativity says that the following is true for ",
" free particle:",
"/c",
" = ",
"/E,",
"where ",
" is the velocity, ",
" is the momentum, E is the total energy, and c is the speed of light.",
"SR also says that for any free particle:",
"E",
" = (mc",
")",
" + (",
"c)",
".",
... | [
"A particle with 0 energy wouldn't exist, I assume. It would be like having a wave with no amplitude."
] | [
"A particle is an excitation of a field. If there's no energy, there's no excitation; if there's no excitation, there's no particle."
] |
[
"What allows a screw to become \"tight\"?"
] | [
false
] | I understand that it becomes harder and harder to turn as it gets deeper because of the friction, but what allows it to get "tight" at the end? I know it cannot sink into the wood any farther, but what makes it stay tight to where it is difficult to turn it back the other way and remove? | [
"The other comments seem to be addressing friction only in the threads. Most screws have a \"head\" that will be flush against the wood when the screw is all the way in. When you fully tighten the screw, there is a force between the head and the surface of the wood since the head is trying to press into the materia... | [
"When you drive the screw in the material, the friction builds up an opposite torque. When the torque you apply gets equaled by the friction torque, then the screw feels tight.",
"If you didn't drill a hole first for the screw, then you also get side and front pressure from the wood, that adds to the friction tor... | [
"Static friction. As you're turning the screw, it's already overcome static friction, and you just have to overcome the dynamic friction of the system. Once you stop, though, you have to overcome the static friction first to move it.",
"You could stop turning the screw at pretty much any point, and it'd become \"... |
[
"Found this in a sleepy seaside cemetery. I'm hoping you can tell me what it means."
] | [
false
] | [deleted] | [
"Those are Maxwell's Equations in Gaussian unit form. See ",
"http://en.wikipedia.org/wiki/Maxwell's_equations",
" for more information, but in order they're Ampere's Law, Faraday's Law of induction, Gauss' Law and Gauss' Law for magnetism. Together they describe the interactions and behaviour of electric and m... | [
"Those are ",
"Maxwell's equations",
". They describe the basic laws of electrical (E) and magnetic (B) fields, including the way their mutual interaction is related to the speed of light."
] | [
"Non-science post because this is some non-science ",
"here",
". ",
"I was curious why these things might appear on a tombstone (beyond the understandable obsession that one might have with physics). After reading around a few results that discuss Maxwell's Equation from a non-scientific standpoint, it seems ... |
[
"Quick question involving ants and gravity"
] | [
false
] | So the other day I was watching some ants climb up a tree, and wondered how high would an ant have to be for it to die from falling, or is it impossible for an ant to die from falling? | [
"Ants, being tiny, have a high air resistance:mass ratio, and thus have a very low terminal velocity, which they reach very quickly. What this means is that for any fall height over a metre or so, they'll hit the ground at the same speed, which isn't sufficient to do them any particular harm.",
"See ",
"here",
... | [
"It is impossible for ants to die from falling (under normal conditions) because they reach their terminal velocity very quickly which is quite low."
] | [
"Thanks for satisfying my question with a great source :D"
] |
[
"Without observing the sky, is it possible to prove that the earth is rotating/orbiting?"
] | [
false
] | [deleted] | [
"In the case of the Earth's rotation, yes, for instance, a relatively straightforward demonstration of the rotation of the Earth can be obtained with a ",
"Foucault pendulum",
"."
] | [
"On a larger scale you could take atmospheric measurements across a hemisphere to identify the coriolis effect from which you could infer rotiation."
] | [
"You could measure the Earth's rotation using the coriolis effect. Taking the Earth as a stationary frame of reference, moving objects experience a small force due to the earth's rotation. The faster the object is moving, the larger the force. ",
"For example, moving due east causes an object to experience a smal... |
[
"How are these kinds of layered stones formed? (Image inside)"
] | [
false
] | Some nine years ago, when I was still in school, I had found a strange looking stone with layered patterns. Recently looking at my old stuff, I found it again. Which makes me wonder how these kinds of layers are formed: Edit: The sample is about 4 centimeters long, 3 centimeters wide and about 2.5 centimeters in height... | [
"Retake the photo with a scale and a different angle or two. Where did you find it?"
] | [
"It's difficult to say without more information (scale, where you found it, multiple angles, etc.). We can make some educated guesses though. The first thing that comes to mind is foliation. This occurs in metamorphic rocks (rocks that have been subjected to heat and pressure, but not enough to fully melt them) and... | [
"Finding it on a playground makes things a little harder, since we don't know its place of origin. The yellow/orange/brown color is almost certainly a weathering product (oxide formation). If you were to break the sample in half you might find a fresh exposure that could tell you more. I don't necessarily recommend... |
[
"If we ever succeed on colonizing other planets, would their descendants be able to return to Earth?"
] | [
false
] | I once heard that if humanity colonizes Mars, the low gravity there would cause the colony's inhabitants' physiology to adapt within a generation, making it difficult for that generation to return to Earth without adverse effects. Is there any truth behind this? Edit: Fixing a mistake. | [
"Two points here:",
"Speciation takes a ",
" time. You're not going to cause genomic changes in a single generation, or even 100 generations. So the descendants of terrestrial martians would be perfectly able to adapt to normal earth conditions, if they were relocated early enough.",
"Mars' environment is sim... | [
"It depends how sci-fi-ey you are talking here. If its just people living somewhere else, probably not. Speciation takes quite awhile, and one generation would probably be insufficient to create meaningful reproductive isolation. ",
"Now, I have heard of problems with people experiencing long term exposure to zer... | [
"You are correct that it is easy to grow accustomed to a certain gravity, just like astronauts' muscles start disappearing if they don't exercise. ",
"The same would happen on mars quite quickly, but they would be able to come back to earth. Just feel very weak and heavy for a while.\nYou can compare it to living... |
[
"Why does sound have a speed?"
] | [
false
] | Why can't faster or slower moving particles be heard? | [
"Although there is a speed of sound, that speed is not fixed but instead is dependent on the medium through which it moves. Sound moves producing a pressure force on the atoms surrounding the source. The greater the density of those atoms, the greater the speed at which it will propogate.",
"Sound will move slowe... | [
"That's not what the question is about. Ultrasound and infrasound waves both travel at the same speed as audible sound."
] | [
"A very simple metaphor is imagine you are looking at pool (billiard) balls. Now imagine those pool balls are spaced in a straight line very close together so that they are just barely not touching each other. If you were to hit the first ball, it would travel the tiny distance until it hit the next ball and so on ... |
[
"Is a true artificial intelligence only science fiction or will we be able to create one?"
] | [
false
] | [deleted] | [
"I've worked and studied in AI for almost 10 years now, what follows is just my opinion. ",
"I haven't seen much progress in creating a human-like intelligence recently. The explosion in the field since 2000 has been more on the machine learning side; this is what Watson used to win on Jeopardy, and what most tec... | [
"I'd describe myself as being on the biological side of AI and I'm intimately aware of how crazy pants difficult it would be to recreate the brain. There's so much going on in there, there's a great quote by the naturalist Gilbert White \"the most complex part of nature is the part you're studying.\" The more you... | [
"A big flaw with the \"AI = problem solving\" approach, besides the fact that there are an infinite number of problems out there, is that in early AI research people tended to focus on problems that are difficult to humans, which are very different from problems that are difficult to computers.",
"My favorite exa... |
[
"Can deaf people suffer from ear injuries from loud noises?"
] | [
false
] | I am very curious about this | [
"The short answer is mostly yes. Assuming that the eardrum and middle ear structures are intact, very loud noises could still cause injuries, such as a ruptured eardrum. While this would be painful, a deaf person obviously wouldn't notice any hearing problems, since they were deaf to begin with.",
"In the case ... | [
"Deaf guy here. My eardrums still operate, just the nerve doesn't send the signal to the brain. In loud situations, I can feel my eardrums max out so yes, 'most' deaf people can still get injured by sound. Sound is, afterall, merely a vibration of air. Those differences in pressure radiate on the eardrum and other ... | [
"Would this cause problems with other non-auditory functions of the ear like Balance?"
] |
[
"Why do we call that which is within CMBR the universe? Isn't there reason to believe that there's more to the universe than that?"
] | [
false
] | I see posted a lot as a representation of the universe, but what bugs me about that statement is the idea that there's more to the universe than just what's in that bubble. Why don't we call what's inside the bubble the "cosmos" or something else, don't you think that it's a bit bold to say that what's inside the CMBR ... | [
"these are all terms that mean something specific within science and not necessarily the same thing to the general public. The universe is everything in existence; anything we can, in principle measure, right? Within that universe is a portion we call the \"observable universe\" that many people aren't particularly... | [
"yeah of course there's more. There's our \"observable universe\" the bit we can see, which is only a small part of the overall universe"
] | [
"Well I'd rather the public learn the proper scientific meanings for these words. I'd rather increase scientific literacy than have to translate old publications to fit modern linguistic patterns. That's what we try to do here. We try to help educate people on the difference between observable universe and \"univer... |
[
"How do we measure the mass of an electron ?"
] | [
false
] | null | [
"And the oil drop experiment works if you have a precise measurement of the charge-to-mass ration, wooooo.",
"It's like getting Newton's constant by dropping something and seeing how long it takes to fall. Works fine if you know the mass (and radius) of the earth, sure, but if you tried dropped anything why would... | [
"And the oil drop experiment works if you have a precise measurement of the charge-to-mass ration, wooooo.",
"It's like getting Newton's constant by dropping something and seeing how long it takes to fall. Works fine if you know the mass (and radius) of the earth, sure, but if you tried dropped anything why would... | [
"The charge of an electron is a fundamental constant of nature,",
"So is the electron mass. Neither are any more fundamental, and neither are any more well-known a priori.",
"This experiment only measures the charge-to-mass ratio q/m. It was first done in 1897, and for about fifteen years, that was all that wa... |
[
"[Physics] If an object has a higher mass, when it's energy is higher, wouldn't that end up in a loop where you would have to recalculate Energy and mass infinitely times?"
] | [
false
] | null | [
"In the rest frame of a particle, its energy and mass are related by E = mc",
". If you could somehow measure the rest energy of the particle directly (that's ",
"), there would be no reason to correct your measurement of ",
". You would just get E = mc",
". Your measurements would be consistent with that e... | [
"I see. But are we able to measure that rest energy? Or is everything we calculate just a value which is very very close to the real one, and we don't know the real one?"
] | [
"All measurements have error. "
] |
[
"Why have some species (like ducks) evolved to make copulation difficult?"
] | [
false
] | This is a question that has been bugging me for quite some time now. From : Male ducks force copulations on females, and males and females are engaged in a genital arms race with surprising consequences. I understand why evolution might favor males of a species that force themselves on the females, but why do the femal... | [
"The adaptations to resisting copulation have more to do with female mate selection than resisting insemination in general. If the female can't reliably ",
" resist unwanted copulation attempts from males and thus choose their mate that way, then it makes sense to dodge unwanted fertilization ",
". The weird sp... | [
"Basically, both sexes would benefit from having control over who inseminates the eggs, and so have evolved elaborate genitalia to avoid relinquishing that control. This is a conflict that is actually not uncommon, but doesn't often manifest itself in such a violent way.",
"Males of ducks have very large penises... | [
"There are many things that might make a male 'more fit'. From a natural selection standpoint, this could include things like being faster and stronger, but also things unassociated with ability to coerce females, like having bigger fat stores, being better at foraging, being camouflaged to avoid predation, among ... |
[
"How to assume material wear?"
] | [
false
] | Hello! My question is - how to assume wear of the material over time? I.e.1 - I have a pipe. In time pipe's walls can get thinner due to wear. But how to approximate rate of the wear process over the years? I.e.2 - I have a steel bowl or funnel. I pour granules or flings of a softer metal (let's take copper as example)... | [
"The best way would probably be to a sample of the material and have a lab do some sort of ",
"accelerated wear test",
". There are several different types of standard tests depending on the type of wear - dry abrasion, wet abrasion, metal-on-metal, high or low stress, etc. This still may not give you a number ... | [
"There is still wear. Hardness is only a guideline. Soft materials will still damage hard materials over time. For instance in plastic injection molds, the molds are made of hardened steel, which can be harder than glass, and the plastic is obviously very soft or even self-lubricating in the case of nylon and PT... | [
"This is an old question, but as this is my area of expertise...",
"Your question is covered by the area of Mechanical Engineering known as Physics of Failure. ",
"Predicting how long a material will last is a two step process:",
"1) Stress Analysis\n2) Reliability Assessment",
"Step 2 is what you are aski... |
[
"How long will two 12v batteries heat a small room for?"
] | [
false
] | I would like to set up a bike with a car alternator, put two 12v batteries in parallel, get an inverter and plug a low power heater into it to say, keep my (small)room temperature 22 Celsius in winter. How long would i have to cycle for to charge them?, to heat my room for how many hours? basically is it worth doing, o... | [
"The voltage of the battery is only one piece of the puzzle and on its own doesn't say much about how much energy it contains. The second component is the amount of charge in the battery. This is often measured in Ampere-hour (short: Ah) or milli-Ampere-hour (mAh). 1 Ampere-hour is simply the amount of charge that ... | [
"You'll find that the actual cycling heats the room more than five times as much as the power that ends up in the batteries.",
"Humans are (roughly, and it varies from person to person) 20% efficient. So if you're putting 120 watts into the pedals, your body will be dumping 480 watts of heat into the room just t... | [
"Op, you could work out on a standard exercise bike for exactly the same heat output as the battery contraption."
] |
[
"What would be the difference between the trust required for a same volume and weight ship with the form of pointed cylinder, square pyramid, and a cube to escape earth gravity. How does one go to calculate that?"
] | [
false
] | Title just about sums it up. I was wondering how much of difference does shape actually make as far as the trust required is concerned. | [
"If the area of thrust isn't a factor then I'd say the differences are negligible. v(dm/dt) is the thrust forces, and v relies on sectional area of propulsion and the density of fuel."
] | [
"I was thinking that the other thing that might affect the needed trust would be air resistance and since it would be bigger in some cases depending on form it would require greater thrust to achieve the same results, wouldn't it?"
] | [
"That's not what terminal velocity means.",
"Terminal velocity is highest speed to which a falling body can be accelerated ",
". If you add more thrust, you certainly can go much faster. "
] |
[
"Does death unrelated to the heart stop the heart immediately?"
] | [
false
] | Let's say someone was killed by a blow to the head, or drowned, or any other way that doesn't damage the heart or cause lethal blood loss. Does that person's heart stop at the moment of death? If it doesn't how long does it continue to run? Does it slowly fade, or stop abruptly if it continues? | [
"In most cases, the moment of death would be defined by the irreversible cessation of a heartbeat. In the scenarios you mentioned:",
"Patients may die by brain criteria, also called ",
", if there is irreversible cessation of function of the entire brain. These patients will continue to have a heartbeat for a s... | [
"Thank you!"
] | [
"As below, it is really important to define death by either the brain or the heart. The heart can continue to pump independent of the body. In the case of severe whole body trauma the heart can be ripped clear of the body and continue to pump on the ground. ",
"Edit. So, not necessarily. The heart has tissues on ... |
[
"A few questions about Quantum Physics and Omega point theory"
] | [
false
] | I'm a bit confused about different theories I am being presented through Frank Tipler, which ones violate others, etc. Any help from someone knowledgeable would be GREATLY appreciated. Here are the conclusions presented in the article: 1) Assuming the existence of black holes, and given Hawking's conclusion that black ... | [
"Most scientists are wrong their entire life. The great scientists, those that are right, are often only right once in their entre career. The legends are the ones that are right more than once. ",
"I'm sure Tipler has pretty thick skin by now, and given how nutty his theory sounds I'm sure he's been told he's wr... | [
"Thank you, the ability to cite a source for this will be very helpful",
"edit: This was for research I am doing for a (non-science) paper I am submitting for a class. The Omega point theory was coined by another professor at my university, and my paper is going to suggest he is wrong. This could be interesting."... | [
"Thank you, the ability to cite a source for this will be very helpful",
"edit: This was for research I am doing for a (non-science) paper I am submitting for a class. The Omega point theory was coined by another professor at my university, and my paper is going to suggest he is wrong. This could be interesting."... |
[
"Does the light from a photographic flash harm plants?"
] | [
false
] | Hey guys, I'm quite new when it comes to photograph in open spaces, and I ended up using my photographic flash - standard Nikon one, nothing sophisticated - in the botanical garden of my town. Sadly the guard - military one - said that I couldn't use the flash there and just say "no because I said so" when I asked for ... | [
"To add to that, the actual reason flash photography tends to get banned in public places is simply because it's extremely distracting/annoying to everyone else."
] | [
"The flash on a portable camera comes no where near the intensity of being able to harm a plant. Normally, the flash on a camera is built to mimic the spectrum of natural light, or white light. This is because that is what we are used to seeing things bathed in. The levels of light that your flash is putting on the... | [
"Thank for the answer! I should have thought about that and tried to argue with him."
] |
[
"Would a drinking glass with a hydrophobic outer surface produce less condensation and stay cooler for longer?"
] | [
false
] | When water vapor condenses on a surface like a cold drinking glass it releases some heat energy in the process. Would a hydrophobic surface reduce condensation, thus reducing the amount of heat energy the drink absorbs? If so, how much cooler would the drink stay? | [
"Could this question be answered by spraying Never Wet on the surface if a cup? If so, I will go perform this experiment in my garage with a plastic cup, coated with the Never Wet product, and fill it with ice water, placing that cup next to an untreated cup with the same amount of ice and water and see which cups ... | [
"Actually, a hydrophobic coating would probably warm your drink up faster.",
"Why? When a droplet forms, it takes up space on your condensing surface (the outside of your glass) and prevents new droplets from forming there. Adding a hydrophobic coating wouldn't do much to prevent condensation, but would help to... | [
"Yes. Please perform this experiment. I recommend that you buy two identical thermometers, and stick them in the cups of water without removing them for the duration. In this way you can determine and document the temperature change every couple of minutes.",
"Then perform the experiment again with the thermomete... |
[
"If the Empire State Building were in space, would a single person have the power to move it?"
] | [
false
] | Assuming any sort of internal elasticity was negligible, and there was some sort of immoveable wall to brace oneself against (this is hypothetical, after all), could the building or something of similar mass be moved by a single person? | [
"Yes it will absolutely move, although very slowly. If a person were to push the tower in space, then an equal force 'F' would act on both the person and the tower in opposite directions. ",
"Acceleration = Force / Mass, which means that given the same force, an object of greater mass will have a smaller accele... | [
"Give me a long enough lever, a fulcrum, and a place to stand, and I could move the world. "
] | [
"Is this true even as the Empire State Building stands, embedded in concrete? Would it move a tiny fraction of a nanometer if I just pushed on it? If yes, would it only move locally, e.g. the concrete around my hand, or would there be an infinitesimal twitch of the whole building?"
] |
[
"Does molten iron have magnetic properties?"
] | [
false
] | Could I wave a magnet over a pool of molten iron and pick some up? | [
"Molten iron does have characteristic magnetic properties, but these are very different from those of solid iron at low temperatures. The easiest way to understand magnetism is that each electron has a ",
"magnetic moment",
", (it acts like a small bar magnet), the orientation of which is determined by a proper... | [
"Interestingly this effect shows us how the Earth's magnetic field orientation flips occasionally.",
"At the mid-atlantic ridge (in the mid atlantic) 2 tectonic plates are moving away from each other. This leaves a gap where molten material (including iron) rises up, and cools on the seabed, essentially creating ... | [
"To be slightly (OK, very ) pedantic, this shows us ",
" the field orientation flips, but not ",
". I'm not sure if we know how it happens particularly well."
] |
[
"Do siphons have a maximum tube height and how is it calculated?"
] | [
false
] | [deleted] | [
"Because the pressure in the fluid cannot dip below 0 Pa (actually it can't dip below the liquid's vapor pressure at whatever the fluid's temperature is, which will tend to reduce the maximum height difference), the maximum height fluid can travel up a tube due to a siphon is (P",
")/(ρg) where P",
" is the pre... | [
"That's actually really high."
] | [
"If you try sucking water through a straw any higher than ~32 feet (don't use your lungs, it's impossible. Try a vacuum pump) the water will actually boil!",
"There was some studies regarding using this mechanism to desalinate water as an alternative to distillation or reverse osmosis, which are moth very energy ... |
[
"Have any animals developed projectiles?"
] | [
false
] | [deleted] | [
"Solid projectiles:",
"Some tarantulas fling stinging hairs",
"Many a zoo visitor has had poo flung at them by a ",
"monkey or ape",
" (that one's an ape---a chimp---in spite of the title)",
"California ground squirrels fling sand",
"Liquid projectiles:",
"Spitting cobras",
" spit",
"As do ",
"a... | [
"awesome response, great examples! i enjoyed the videos thank you!!"
] | [
"Apes and monkeys can throw sticks and stones and supposedly feces. I believe there are some snakes or reptiles that can spit venom. I vaguely recall seeing a documentary where some kind of a fish came to the water surface and squirted water out of it's mouth to knock an insect off a leaf. It fell into the water wh... |
[
"How common is cancer among wild animals with little to no contact with humans?"
] | [
false
] | null | [
"Wild animals are not free from pollutants, so contact with humans is not the only thing to consider.",
"Cancer has a lot to do with size, so humans are a lot larger than rats, so we should get more cancer. Also, it has a lot to do with longevity and humans live a long time. What's interesting is whales and ele... | [
"Tasmanian devils have a kind of cancer that is killing them off. Basically they transmit it by biting each other and it eats away their face as it grows. It was decimating populations last I heard about it, and it's believed to have evolved naturally from a female devil that's long since died. It's a pretty inter... | [
"The number one risk factor for cancer is age. The longer you live the more chances you've had for a stray bit of ionising radiation or reactive chemical to alter your DNA in exactly the wrong way to get cancer. Basically if you live long enough, you will die of cancer. Human are among the longest lived animals, so... |
[
"Is there a -- and if so, what is the -- \"feedback\" mechanism from the bladder to the kidneys? (Is there a message like, \"Stop already!!\"?)"
] | [
false
] | Like normal humans, I wake up in the morning, put on my glasses, and take a humongous morning pee. It has not been an emergency to get to the bathroom; I am not in pain; etc. Thing is, I can void nearly the same volume an hour later. It's almost like, say, at 3ayem the bladder told the kidneys to take a break for a fe... | [
"No. The kidneys keep making urine regardless of what state the bladder is in. This is necessary because our bodies make waste continuously, so we need to make urine continuously. If there is a distal obstruction impairing urine flow (large prostate, big stones, neurologic injury, etc), the urinary tract dilates an... | [
"At night your pituitary releases more of a hormone called \"antidiuretic hormone\" (ADH) which is an important part of the system that regulates how much fluid stays in your bloodstream. It conserves fluid in your body by making your kidneys let out less water. They still filter out waste, but they bring water bac... | [
"This, and also - the bladder is more stretchy than we realize. We can go a lot longer than that initial \"gotta go\" feeling before we lose urinary control, which is why you can last all night but \"need\" to pee a few times a day."
] |
[
"Can becoming fat really be a 'hormonal' thing, surely you still have to eat enough food to get fat in the first place and can lose it in the same way?"
] | [
false
] | It's pretty much all there in the title. | [
"As stated, hormones can affect the secondary aspects of caloric intake (hunger, stress, habits, etc) but they do not effect the laws of thermodynamics. ",
"Energy is not created or destroyed, only transferred. ",
"Intake more calories than you expend? Gain mass.",
"\nIntake less calories than you expend? ... | [
"Not sure who's moderating, but would be wonderful to tighten up the discussion in general on AskScience with more adherence to the whole \"based on repeatable analysis published in a peer reviewed journal,\" \"free of anecdotes,\" and \"free of layman speculation\" things."
] | [
"The differences can be negated by a single cookie or soda. That's why they aren't justifiable.",
"The difference between obesity and healthy weight can also be as little as a single soda per day. People don't become overweight over night. ",
"Anyway, you are probably correct that other factors are much more im... |
[
"Why are smooth metal metal wheels used in railroad trucks?"
] | [
false
] | Increasing the traction of rail wheels would allow the cabs to be lighter and increase fuel efficiency. Gym shoes, car tires, and tank tracks all use threads to increase grip. The same principle can be applied to rail wheels. Using a crosshatched metal surface, or wrapping the wheel in a thick band of rubber would incr... | [
"Tread doesn't increase grip, it decreases it (in your shoe and tyre examples at least). It is needed on road cars and shoes etc to disperse water in wet conditions, allowing the rubber to grip the surface rather than float on a thin layer of water. \nTrains also need to slide across the surface of the rails slight... | [
"First, metal on metal wheels don't suffer in efficiency for lack of traction. It just makes them take somewhat longer to get going and to stop.",
"Why is metal used? Two reasons.",
"First, cost. If you lined a loaded cars wheels with rubber it would squish out of the sides under the pressure and tear off withi... | [
"Not sure it exactly answers your question but ",
"it's awfully entertaining.",
" Feynman on train wheels."
] |
[
"What happens when a planet falls into a star?"
] | [
false
] | Is this possible? Or would a planet be destroyed by the heat and solar radiation before it got to the surface of a star? | [
"As the planet got close enough, probably seismic activity would break it apart",
"Seismic activity, sure, but it probably wouldn't break apart - or at least not if we're talking Earth crashing into the Sun.",
"The ",
"Roche Limit",
" is the critical threshold here; if you have a small body and a large body... | [
"In 1992 an asteroid broke apart and crashed into Jupiter. It would probably be something like that.",
"As the planet drew nearer, its temperature would change, likely killing any life on it. Radiation and solar wind changes would probably overwhelm any EM or atmosphere protection the planet had.",
"As the plan... | [
"The consequences for gas giants however are not the same as the Roche limit is outside of the star (roughly at 0.02 AU). A number of Hot Jupiters find themselves at close to this limit (but we have no observations of a Hot Jupiter within the Roche limit). So we expect that giant planets get tidally disrupted (ther... |
[
"What were domesticated animals (cows, horses, dogs, etc.) like before domestication, and what caused them to domesticate?"
] | [
false
] | null | [
"As far as can be told the path to domestication was different for different animals.",
"Livestock (cows, sheep, goats, pigs, chickens) were likely herded, caught and penned. With livestock domestication occurring around the advent of agriculture in the Neolithic period aprox 11,000 years ago. Once we had control... | [
"Excellent and thorough answer. I would like to add that chickens were domesticated >5 thousand years ago in Asia from the red junglefowl, a wild species of pheasants. ",
"https://en.wikipedia.org/wiki/Red_junglefowl"
] | [
"Well,that question really has a very long answer. In a nutshell,people kept animals and allowed the friendliest ones to breed,kept the friendliest young to breed,rinse and repeat. Gradually there were changes in the animals physically and visually and those with the most interesting markings were kept as well. Peo... |
[
"How and why does psychotherapy work?"
] | [
false
] | [deleted] | [
"I didn't intend to contradict you at all, I meant to offer further understanding of CBT from the perspective of a past patient :) I realise my comment was ambiguous tho."
] | [
"I didn't intend to contradict you at all, I meant to offer further understanding of CBT from the perspective of a past patient :) I realise my comment was ambiguous tho."
] | [
"Talking to a professional does not require you to trust her/him (they are by law obligated to keep your secrets except for extreme cases), they have experience and have heard pretty much everything (hence you don't need to feel like keeping up appearances or think they will think you are uniquelly screwed - in fac... |
[
"In a CNO cycle in a star, where do the intermediary particles come from?"
] | [
false
] | Massive stars use a CNO cycle to fuse hydrogen into helium, but this process requires some intermediary particles (Carbon, Nitrogen, Oxygen). But how do these come into play? Are they there to begin with or are they created within the star? | [
"There can be some carbon in the star to begin with, if the star was formed late enough after the beginning of the universe.",
"If there are no carbon, or at least not enough to allow CNO cycle to fuse helium at the high enough rate, helium would accumulate in the star's core in greater and greater concentration,... | [
"Large stars have very inefficient burns due to the lack of convection throughout the outer envelope, so there's lots of hydrogen around when you get enough carbon to start CNO. I'm not sure exactly how much carbon it takes, but it's very little since it's a catalytic process. ",
"This paper",
" suggests only a... | [
"Where would the hydrogen for the CNO cycle come from if the star started the triple-alpha process already?"
] |
[
"Do planet orbits lie on the same plane?"
] | [
false
] | Solar system models show the planets orbiting on the same . I was wondering if they have orbits that aren't on the same plane and we just model the solar system like that for simplicity. | [
"The eight remaining planets (sorry pluto) orbit in ",
" the same plane. The reason being that they formed from the ",
"Protoplanetary disc",
" that formed around the young sun billions of years ago. In general, clouds of gas collapsing under gravity tend to form discs, because of conservation of momentum/a... | [
"It doesn't form a perfect plane.",
"But in a simplified explanation, you can imagine a rotating gas cloud - its rotation is in a single plane. As it collapses to form a star, its angular momentum must stay the same. Thus, any axis of rotation is conserved. Any process involving orbit would generally respect this... | [
"It doesn't form a perfect plane. ",
"That's because you included a dwarf planet from the Kuiper belt."
] |
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