title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How do astronomers both find things so far away that aren't objects, like the KBC Void or Boötes Void, and identify objects' properties like atmosphere, temperature, and whether there's water and such on or in the object?"
] | [
false
] | I understand we have VERY powerful telescopes and fairly advanced technology, but if you look at any photo of the night sky, no matter how high the quality or magnification, the sky is so densely packed with objects that it seems totally impossible to identify certain 'Voids' that are basically just gaps in between sta... | [
"For voids, we essentially look at how far away all the objects in a given part of the sky are, this can be done using redshift (See ",
"here",
"). When a survey was done by Robert Kirshner, Augustus Oemler Jr, Paul Schechter and Stephen Shectman of Galactic redshifts in 1980 they discovered that there was an a... | [
"Here's how we work out what a distant planet's atmosphere is made of. When light passes through the planet's atmosphere, some wavelengths of it are absorbed by the gasses and then re-emitted. However, the direction these wavelengths are emitted are essentially random, so when someone on Earth looks at the light co... | [
"Note that for this technique to work, we need the planet to have an orbit that takes it between Earth and the star it is orbiting. Which is not that common. That's why we have only analysed a few atmospheres (a few hundreds to my knowledge). This is also one of the techniques used to detect those planets. "
] |
[
"If a 1000 kg cube impervious to all heat/pressure/radiation was dropped into our sun, how far would it sink before reaching equilibrium with the gravity of the sun and outward force of fusion?"
] | [
false
] | Considering the photosphere as the "edge" for measuring how far the object has descended. Edit: The hypothetical object is as dense as the sun's core. | [
"It would sink until it reached a depth where it was the same average density as the gas around it. This is essentially the same as what happens in the ocean: your buoyancy force (the force holding up a submarine or fish) is equal to the weight of the water you're displacing. If you weigh more than the water you're... | [
"Don't forget radiation pressure!",
"Yeah, that's the tricky bit - it's going to depend on how transparent your material is. hmm...",
"On another note, is there a functional parameterization of that curve?",
"Well, it depends on how accurate you want to be! It's usually just done numerically (like this is her... | [
"Don't forget radiation pressure!",
"On another note, is there a functional parameterization of that curve?"
] |
[
"What are some interesting examples of humans influencing the evolution of a species?"
] | [
false
] | Most people who've taken a basic course in biology know about the speckled moths that turned black during the industrial revolution due to pollution. I want to know what other examples there are of humans influencing the evolution of other species. The more interesting or unexpected the better. | [
"Elephants are evolving to lose their tusks",
" because poachers selectively kill elephants with the largest tusks. What had been a rare trait is now advantageous for elephants, because no poacher is going to kill an elephant without tusks. In some places over 50% of elephants have no tusks. Those that do have... | [
"I responded to a ",
"similar question",
" in ",
"r/AskScienceDiscussion",
" a few days ago, so I'll repost it here (assuming that's allowed). I actually used the exact same example with elephant tusks as the ",
"u/dromio05",
"'s comment! (And resistance to drugs is also a great example).",
"Artifici... | [
"I responded too some days ago similar question. I bring it to you: ",
"Just to add a very interesting example. ",
". ",
"In short: They developed samurai faces in their shells because people in the area avoid to take the ones who has a face-like pattern. This human behavior leads to a high face-like poblat... |
[
"How (by natural processes) are nutrients added and changes made in an area of soil over time to make it fertile?"
] | [
false
] | null | [
"This highly depends on the geology of the area.",
"One example is coral atolls. In tropical, but shallow seas, coral reefs build up and up until they break the surface to create a small baren island. Seafaring birds tend to be the first visitors. The birds eat fish and leave deposits on the island. Some times th... | [
"The nutrients in soil are released by the breakdown of rock forming minerals. Rocks weather into mineral grains, which slowly react with water and dissolved gases to convert into things like clay and silica, while also releasing potassium, phosphorus, magnesium, calcium, and other necessary elements. Nitrogen is ... | [
"So the nutrients in soil are these ions: K",
" Ca",
" Mg",
" Na",
" NH4",
" Fe",
" Zn",
" Cu",
" Mn",
" as cat ions and NO3",
" PO4",
" (normaly as H2PO4",
" or HPO4",
" SO4",
" MoO4",
" BO3",
" as an ions",
"This is what we in agriculture talk about as soil nutrients. Very long a... |
[
"Something I've always wondered is why have we never landed a rover on Venus?"
] | [
false
] | null | [
"'We' have - the russians did."
] | [
"The russians landed probes that collected atmospheric data and stuff like that. Nothing like the stuff they're doing on Mars right now."
] | [
"Venusian surface conditions are kind of extreme. The Venera probes only survived for 23 to 120 minutes each."
] |
[
"Why do positrons only have positive spin?"
] | [
false
] | [deleted] | [
"I'm not sure where you heard positions only have positive spin, but you're misinformed. By positive and negative spin, I'm assuming you mean spin +/- 1/2. Positrons have the same spin as electrons. They are identical to electrons in every way except they have the opposite charge."
] | [
"Should I delete the question?",
"I'd say not to. If you delete it, no one else can glean any knowledge from it, and (in theory) if you leave it, people also won't have to ask it again."
] | [
"Should I delete the question?",
"I'd say not to. If you delete it, no one else can glean any knowledge from it, and (in theory) if you leave it, people also won't have to ask it again."
] |
[
"Question about the Ask Science guidelines... Observer != Conscious person?"
] | [
false
] | I noticed the following in the guidelines section, under the Philosophy of Science/Logic heading. Why is that an important distinction? Sorry, if this has been asked before. | [
"It's pointed out in the FAQ because it's common to confuse the jargon term ",
" with the common English term ",
" (i.e.: a conscious person/animal who observes something), which can lead to many questions based on this faulty premise.",
"Here are a few previous discussions on this kind of subject:",
"http:... | [
"Hello: Your question is stuck in the spam filter, and I think that you need to resubmit with a different title. If you rephrased your title to something like \" Why, in quantum mechanics, is the observer specifically specified as not a conscious person\", it would garner more attention, and wouldn't look like a di... | [
"Hmm, very interesting... Thanks for the reply!"
] |
[
"Is tungsten carbide-coated D2 steel susceptible to corrosion?"
] | [
false
] | null | [
"Without really specific description of requirements, standards, and environment, it can't be said absolutely but...no, it's not.",
"In open-air at room temperature, Tungsten Carbide offers very good corrosion resistance (does depend slightly on the binder being used). In combination with D-grade steels which als... | [
"As a fellow materials scientist (who took a shot in the dark) I agree with this...mostly. I just think it's worth noting that tungsten carbide and D-grade steel are both pretty good in most (reasonable) environments",
"Also, we all know Face Centered Cubic is what's up. /unnecessaryfeelingoflatticesuperiority"
] | [
"As a fellow materials scientist (who took a shot in the dark) I agree with this...mostly. I just think it's worth noting that tungsten carbide and D-grade steel are both pretty good in most (reasonable) environments",
"Also, we all know Face Centered Cubic is what's up. /unnecessaryfeelingoflatticesuperiority"
] |
[
"Why is neutron emission so harmful?"
] | [
false
] | null | [
"Unbound neutrons can collide with nuclei in a target materials and result in a chain reaction of potentially harmful effects.",
"The neutron will impart a large amount of kinetic energy to a nucleus it collides with causing it recoil and become ionized. This heavy charged ion (HCI) can then collide with other at... | [
"It's not the neutron itself that is really dangerous, it's the nucleus that it hit that do emit high energy photons to lose the energy acquired in the process. It makes neutron emissions extremely dangerous.",
"Those high energy particles can then go around and damage chemical bonds, break molecules (including D... | [
"It can basically disrupt chemical bonds in the body through the ionization of hydrogen in molecules. Read more ",
"here",
"."
] |
[
"Is Magnetism Simply Angular Momentum at the Atomic Level?"
] | [
false
] | (As I understand it, and probably way off) Imagine electrons that exist in the metallic cloud of valence electrons contained within a bar magnet. This magnet has a lot of free flowing electrons within the iron. At the North pole the electrons are spinning in one direction, who knows, maybe similar to a vortex. At th... | [
"I'm not sure whether your question is why spins would line up in a ferromagnetic material, or why lined-up spins would cause a magnetic field -- I'll try and give a quick answer to both.",
"For the first, ferromagnetism is basically a result of the Pauli Exclusion principle (what isn't, right?). As fermions, an... | [
"Fundamentally, a magnetic field is a relativistically transformed electric field. In other words, when charged particles are moving, there's a magnetic field around them.",
"I still don't really understand ferromagnetism, though. I mean, I understand that it comes from the \"spin\" of the electron, but then I'm ... | [
"This",
" may help. I believe the spin of all the electrons adds up in the magnet and amplifies. I don't completely understand it myself, but that article helped clear some things up for me."
] |
[
"This might sound like a stupid question, but was the sky pitch black eons ago?"
] | [
false
] | I’m new to this sub and I was curious, since I had nothing to answer this question with other than my own headcanon. So this might actually have a short answer than expected. So light takes a super long time to travel right? Since what we’re seeing up there (outside of the solar system) are dead or dying stars and the ... | [
"Within the galaxy, the light travel times are actually quite short. The whole Milky Way is only about 100,000 light years across, and we're about 30,000 light years to the centre. But most of the stars you can see in the night sky are less than 1,000 light years away, and many are less than 100 light years away. I... | [
"To expand a little bit on this (unsurprisingly) excellent answer from ",
"u/Astrowiki",
", ",
"this table",
" lists the hundred or so brightest stars when viewed from the earth. Note that only six are more than 1,000 LY away and the most distant is just a bit over 2000 LY away (I believe this table mis-lis... | [
"As the sun wavers up and down in its orbit around the milky way, does it have to pass through any significant gas clouds on its way? And is it possible this may obscure a large number of stars in the sky at some point in the future?"
] |
[
"How do I derive a form of the Navier-Stokes Law which realistically reflects the vorticity surrounding complexly spinose Odontopleurid trilobites in conditions of incompressible steady flow?"
] | [
false
] | The recurring emergence of extreme spinosity in certain Trilobite lineages in the Paleozoic has been interpreted as adaptive specialisation to a planktonic lifestyle. However, Stokes Law merely demonstrates that a sphere of a given diameter may show suspension behavior in conditions of incompressible steady flow, for a... | [
"Well, you are on point with your observation that the approximation is too simplistic. One way to tackle your problem without approximating your odontopleurida as spherical is to describe their volume using ",
"spherical harmonics",
". By using this, you can treat them as spatially extended, non-spherical dust... | [
"Thank you for those insights. I'll admit I was initially tempted by the crude effectiveness of I-T-t, but refrained from investing my efforts in that direction in view of the general robustness of spinose ",
" taxa (Consider the loveliness of ",
" for instance",
" ... ",
" is the one on the right; I'm not ... | [
"Try checking out ",
"this paper",
" and skimming through it's many citations. This sounds like a really interesting problem. Is this really how biological oceanographers parameterize all of their planktonic transport models? I'm happy to help you work through some of the Fluid Mechanics and mathematics if you ... |
[
"Would a cat living on a space station gain and shed it's winter coat?"
] | [
false
] | Assuming the the station used internal climate controls that remained steady all year. Would typical yearly (or monthly) cycles observed in the animal kingdom continue to exist when living in space? | [
"You win that bet: bird migration is almost certainly entirely triggered by changing daylight hours."
] | [
"If you can adequately simulate the seasonal changes that normally trigger these events they would certainly occur. If not, I doubt anyone would be able to give you a straight answer right away, though I strongly suspect that cats wouldn't stop losing their fur. It might become a continuous process."
] | [
"The thing that regulates seasonal shedding cycles in mammals is exposure to light. In higher latitudes days lengthen and shorten seasonally, alternately suppressing and stimulating melatonin production, which in turn regulates seasonal hair growth.",
"Temperature and humidity and all those other things apparentl... |
[
"Air pressure \"below\"sea level"
] | [
false
] | If the oceans were to disappear and it were possible to stand at the bottom of the Mariana Trench, what effects would a person feel due to the increased air pressure? | [
"Interesting aside:",
"Volume of the oceans: ~1.3 billion km³ ",
"1",
"Volume of dry air in the atmosphere: ~ 4 billion km³ ",
"2",
"So, if you just completely removed the oceans, the air would have to expand to fill that space. Using the ideal gas law (PV = RT), assuming the total volume doesn't change a... | [
"Except for the air would have to come from somewhere. So really, the question would be: how much air pressure would we have left up here where we normally are? I don't know the answer, but I bet this would cause some problems, especially considering most of the surface of the earth is water at present. "
] | [
"that's a hole though, he's talkin' the entire volume of the ocean.. about 1.3 billion cubic kilometers. "
] |
[
"Does water become marginally more viscous as it approaches freezing?"
] | [
false
] | null | [
"Not just marginally, it's pretty significant. ",
"Here is a plot",
"."
] | [
"You can actually tell there's a difference just by sound if you pour hot vs cold water from one container to another."
] | [
"glass is amorphous but still a solid at room temp, not a super viscous fluid like that myth says"
] |
[
"How much worse could The Chernobyl Disaster have been?"
] | [
false
] | null | [
"Well, at one point the area below the reactor had to be drained because if it came into contact with the water there would be a massive explosion, so three engineers donned wet suits and a flashlight, which broke, and went into the radioactive water to drain it.",
"They lived too.",
"I suggest you check out Fr... | [
"So really only mildly worse. The local effects are somewhat significant, but \"radioactive dust around the globe\" Is about as dangerous as bananas. Considering how much \"radioactive dust around the globe\" was created during nuclear weapon tests, and how big the globe is. The exclusion zone would be larger in th... | [
"Like a real global catastrophe or an equivalent to moving to denver for a year global catastrophe?"
] |
[
"How fast do I have to go to reach Alpha Centauri in 4.37 years (on my clock)?"
] | [
false
] | Alpha Centauri is 4.37 lightyears distant. If I go at 0.01 x , then it woult take me 437 years, because Lorentz contractions are not significant. If I go at 0.99999999 I would arrive in just a few days, since in my reference frame, the distance would shrink and I'd get there quicker. How fast do I go to get there in 4.... | [
"This is a question about relativistic ",
"proper velocity",
".",
"For easy mode: assume you're using convenient units where speed is measured as a fraction of c, and time and distance use the same units (eg years and lightyears), then: γ=sqrt( 1 / 1-v",
" ), and Tp (proper time) = (d/v)/γ. You're trying to... | [
"Something from that link that I never considered:",
"One major problem you would have to solve is the need for shielding. As you approach the speed of light you will be heading into an increasingly energetic and intense bombardment of cosmic rays and other particles. After only a few years of 1g acceleration e... | [
"It's just a matter of setting the traversal time in years to the distance in light years, and finding the proper acceleration, I guess. Hard mode sounds simple when you look at it that way - thanks for the wiki link!"
] |
[
"What do we actually witness when we are shown an image of a 'sonic boom', and why does travelling at such a speed cause such an overt reaction in the air?"
] | [
false
] | null | [
"It's condensed water vapor."
] | [
"Why does it condense? And in that case why does only a certain volume condense?"
] | [
"Increased pressure turns water vapor into liquid water: ",
"http://serc.carleton.edu/images/research_education/equilibria/h2o_phase_diagram_-_color.v2.jpg"
] |
[
"How does squinting help you see?"
] | [
false
] | I happened to forget my glasses today so I had to squint to see the board. This led me to wonder why squinting helps you see things. Is it just a mental thing, or is there something to it? | [
"When you wear glasses you correct light refraction reaching your eyes. When you squint, you reduce the amount of light being refracted, therefore, making it easier to see. There is something called a pinhole occluder that does the same thing. You essentially look through a tiny hole and, if you wear a prescript... | [
"Squinting hard can actually deform the eyeball ever-so-slightly, which in turn can have a small-but-noticeable effect no focal length."
] | [
"When you squint, you're essentially reducing the aperture of your eye. As a result, you limit the light entering your eye to light rays that are essentially traveling straight toward your retina anyway. Rays that are already traveling toward your retina need not be refracted and bent toward it as much as light com... |
[
"Why doesn't an ant die when it falls from a very high place?"
] | [
false
] | null | [
"Surface area vs. volume. ",
"Small animals (anything smaller than a normal sized cat) have such high surface area compared to their volume that their terminal velocity is low enough for them to survive large falls.",
"That's why cats always land on their feet seemingly uninjured. ",
"When I learned this, it ... | [
"I think the answer may be more physics than biology. Have you ever dropped feather? It falls slower than let's say a ball, even though both \"should\" experience a gravitational acceleration of 9.81 m/s",
" The feather is really light but has a high surface area, that's why it experiences lots of air resistance... | [
"Thanks, pal. "
] |
[
"Why are C and T typically the degenerate bases in the amino acid code?"
] | [
false
] | null | [
"Hydrolysis causes the Cytosine to trade its NH2 for an O, turning it into Uracil. This is a spontaneous reaction that is usually caught by the repair protein Uracil Glycosylase, but not always.",
"\nThe same thing happens to a slightly different form of Cytosine: 5-methylcytosine. In this case it trades NH2 fo... | [
"Hydrolysis causes the Cytosine to trade its NH3 for an O",
"It's an NH2 not an NH3. ",
"This is a spontaneous reaction ",
"Definitely true, but also occurs a result of mutagens, ionizing radiation and UV."
] | [
"D'oh, good catch!",
"\nI just meant it was a reaction that didn't need any energy to occur which is part of why it's so common; guess I should have elaborated for clarity :) "
] |
[
"Can we make laser pointers outside of visible wavelengths? (IR, UV, Microwave)?"
] | [
false
] | I have a laser pointer used for pointing at stars, and thought about laser pointers that are outside of the visible spectra. would microwave laser pointers be as dangerous as I'd imagine they are in terms of pointing them at people? | [
"Your green laser pointer? It's actually an IR laser. That IR laser passes through a crystal that takes 2 IR photons and converts them to 1 green photon."
] | [
"That effect is actually a really big deal, because the cheaper green laser pointers actually produce more IR than green. Many of them even omit to send the output beam through an IR-absorbent filter (cost engineering, dontcha know) so the mixed IR/green beam can be powerful enough to damage eyes even if the green... | [
"There are infrared, UV, and microwave lasers (called masers) but you might not find them in the handheld format you're familiar with. ",
"This one",
" for example is a $2000 IR handheld laser."
] |
[
"I just heard about the RH blood group system, but previously had only heard about the ABO blood group system. Do these exist concurrently, i.e. is everyone RH+/- and A/B etc. or are we all one or the other?"
] | [
false
] | I read the Wikipedia pages for these but it wasn't clear to me how it works. I'd also be interested to learn how blood groups actually differ and what that means in practical terms. | [
"The ABO and Rh+/- systems exist independently. If you've heard blood groups described as \"A negative\" or \"O positive\", the positive and negative refer to the Rh type.",
"Blood types are defined by antigens on the surface of red blood cells. These are proteins that hang out on the outside of the cell and act ... | [
"They are independent things. Just like you can be left-handed and wear blue socks (or not) at the same time. There are a LOT of other blood group systems, but ABO and RH are the most important. Some of the others have names like MNS, P, Lutheran, Kell, and Duffy.",
"https://www.britannica.com/science/P-blood-gro... | [
"Just as a correction, there are more than one antigen in the Rh system. The pos/neg is just Rh D, which you either have or don't. There's also C/c, E/e and a few others that aren't usually worth mentioning."
] |
[
"Is there anything in space we can see at two different times because of the bending of light on the way here? How much of a difference could be expected?"
] | [
false
] | I read something like this ages ago and it intrigues me. Can you really see the same thing in two places in the sky? | [
"Yes! Here you go: ",
"Astronomers Watch a Supernova and See Reruns",
"Very, very weird stuff - a combination of a supernova event and just the right alignment of Einsteinian gravitational lensing let astronomers view multiple different stages of a single supernova event.",
"EDIT: Yes, I can actually spell su... | [
"Sounds like you are describing gravitational lensing. Something as large as a galaxy can definitely bend light around itself in such a way that we can see multiple \"copies\" of whatever is behind it. The light may travel further around one side than it does around the other, so in theory yes we can see the same o... | [
"Check out the ",
"Einstein Cross",
". I think this is what you are asking about. It's an imagine of a quasar repeated 4 times by gravitational lensing around a closer galaxy. ",
"Also check out ",
"light echos",
". Sometimes we can see light reflected off of dust to see an event that happened earlier. "
... |
[
"Is there a significant difference of oxygen concentration in the air, during the daytime and night ?"
] | [
false
] | Since plants produce 02 in day and c02 in night , there's surely a difference but i want to know how much ? Does it affect human ? Does it affect the performance of an athlete for example ? Like is he more endurant when he runs during day than night | [
"following your logic, variations in the % oxygen should be about the same as variations in %CO2. CO2 concentration is about 0.04% (or 400 per million). So the variation in O2 concentration can only be ±0.04 percentage points a most. Even then, O2 concentration would only vary between 20.9-21.0%. Anyway, CO2 concen... | [
"Very clear \nThanks"
] | [
"Don't plants respirate all the time but during the day they additionaly photosynthesis? Also because of gases diffusion in open space area without high pollution I think it's not as significiant. IMO your performance during the daytime jogging would be same as night session if the amount of oxygen in the air duri... |
[
"At what mass of feces in your colon does your body feel the need to defecate?"
] | [
false
] | When does your brain receive the signal that causes you to feel this urge? | [
"It's more about volume rather than mass.",
" There are nerves that signal when the colon is stretching, causing the urge to defecate. But you can resist that urge (because, as discussed in another question, many animals prefer to defecate in a location not where they live and eat), and some water is reabsorbed, ... | [
"Not exactly.",
"Intestinal physiology is built to conserve water, a surprisingly rare resource for evolving mammals. The colon attempts to remove as much water as possible, compacting the feces. More liquid feces usually indicates something's wrong, whether it's a viral or bacterial infection, some sort of toxin... | [
"so that's why I always feel the poo shooting out when I enter the bathroom"
] |
[
"Can mosquitoes die if they bite someone with a high blood-alcohol level?"
] | [
false
] | null | [
"This is merely a speculation, as I could not find any information on mosquito's sensitivity to alcohol:\n A human can hardly go beyond the concentration of 0.50% (half of a percent) of blood alcohol and stay alive, and most drunken \"stupor\" cases exist around 0.06% - 0.15% (six percent of a percent to fifteen pe... | [
"Wile generally accepted as fact, the 0.5% BAC max is untrue. Depending on the level of alcoholism, many people can get up to 0.9% or even higher. I work as an EMT, and my personal best is a patient who ended up with a 0.86% after we dropped her off. Highest I have heard of was ~0.92% from another medic in my corp.... | [
"The LD50 means \"Lethal Dose median\" or \"Lethal Dose 50%\" that means that not everyone will die from the LD50 dose but it means that if you pick up a bunch of random people from the streets and give them a dose of alcohol that would be equal to .5% BAC (assuming that .5% BAC really is the LD50) then half of the... |
[
"Can one hear the way another person sounds to themselves by putting a speaker with a recording of their voice up to your throat?"
] | [
false
] | [deleted] | [
"Perhaps make a recording of your own voice then hold it up to your throat and see how it sounds."
] | [
"From a sound engineering perspective there are strategies to mimic how the body alters sound. Not exactly the same but akin to ",
"dummy head recording",
". I'm not a neuroscientist but I would guess that there are other reasons we hear ourselves differently making things more difficult."
] | [
"He means the other way around. He wants to hear what you sound like to you. "
] |
[
"Is obesity as much of an eating issue as we make it out to be, or is metabolism to blame?"
] | [
false
] | With my personal experience, I have been able to eat copius amounts of unhealthy foods and been able to maintain a relatively small and fit figure. | [
"It is mostly eating. Some suffer from disorders that cause them to put on weight but by far for most it is an overeating/eating poorly issue."
] | [
"Certainly there are differences between people. Some can eat ten cupcakes and not gain weight and others seem to gain weight from looking at one.",
"That said it comes down to calories in and calories out. Some people may be more efficient (I am...I eat crap all the time and never gain a pound) and others less... | [
"Certainly there are differences between people. Some can eat ten cupcakes and not gain weight and others seem to gain weight from looking at one.",
"That said it comes down to calories in and calories out. Some people may be more efficient (I am...I eat crap all the time and never gain a pound) and others less... |
[
"Are things in our peripheral vision distorted?"
] | [
false
] | I was wondering if there was any impact on our vision due to the curvature of our eyes, similar to how a map is distorted due to the projection of a 3D image on a 2D surface. Am I thinking this out correctly or does the curvature of our eyes contribute to us being able to see in three dimensions? | [
"I am by no means a total expert but: -",
"We see in 3 dimensions because of having 2 eyes. There is overlap between the two images each eye records. which is why we can see in 3 dimensions although more accurately it’s depth perception.",
"Secondly your brain does a lot of heavy lifting in terms of the image y... | [
"There is a neat self experiment that you can do to show that your vision is not a flat projective map. I got it from a YouTuber called Carykh.",
"Lie on your back in a smallish room near the center and close to the floor and look up at the corners of the ceiling. Depending on where exactly you are you should see... | [
"Amazing! The question that the OP asked is something that I have been asking myself for years, and I break my head trying to figure it out on my own! This question is difficult to find on the internet and I am happy to see that ",
"u/LockedLemming90",
" asked exactly the question in my head in the form of a ... |
[
"Is it possible for the speed of sound in a material to be greater than the speed of light in the material?"
] | [
false
] | null | [
"But if thе idеa of \"thе spееd of light in a matеrial\" doеsn't makе sеnsе, how do wе havе еffеcts likе rеfraction and Chеrеnkov radiation whеrе thе bеhavior sееms to dеpеnd on \"thе spееd of light in a matеrial\"? Is it simply that thе apparеnt photon travеl timе is influеntial, or is it scary stuff with thе wav... | [
"The speed of light in a material should instead be replaced with the propagation of light in a material. I guess I was being facetious as a lot of askscience gets filled with \"speed of light\" discussions. My bad!",
"The wave-particle nature of light is also a little bit of conceptual stumbling block as a pho... | [
"The speed of light doesn't change in a material, just the apparent time it takes for a photon to be absorbed and re-emitted through the material. This is a different mechanism than a sound wave, which is a pressure wave. ",
"There isn't really a meaningful comparison here as I could say on the premises laid ou... |
[
"Reddit, one of my students asked an interesting physics question on string theory and matter decay. I have a physics background (engineer), but am having a hard time answering. Help me out?"
] | [
false
] | Below is the question: Is all matter slowly decaying into energy? According to the string theory, everything from matter to electromagnetic waves and forces is composed of the same fundamental building blocks: extremely small strings of energy (either open-ended or closed-ended). It also theorizes that the different pr... | [
"Energy isn't a substance, it's a quantity. Things don't turn into energy, they have energy."
] | [
"It wasn't an accusation, it was a suggestion. I'm just saying, if he has the motivation to come on askscience and answer questions, it would help a lot of people if he could fix a blatantly false wikipedia article. Hell, that article probably leads a lot of people to come on here with false assumptions.",
"Seems... | [
"Not entirely correct. Photons are gauge bosons and they can be either real or virtual."
] |
[
"Would you be able to trace every living thing's family lineage back to the same singular original source of DNA, or is it not that simple?"
] | [
false
] | I understand that the answer to this, by necessity, needs to be theoretical, if not hypothetical. I have a general idea of how evolution went down, but is it really that simple? That it's thought we all originated from a single source? Are there any other viewpoints on the story of evolution that are a bit different? | [
"A single common ancestor is at least 10",
" times more probable than multiple ancestors."
] | [
"Please explain further!"
] | [
"The link really explains it much better than I ever could, but here's a magazine article that was written about the paper that's a bit more digestible.",
"http://www.wired.com/wiredscience/2010/05/origins-of-life-on-earth/"
] |
[
"Is the act of \"rolling your eyes\" a recent social trait?"
] | [
false
] | null | [
"Well, off the top of my head:",
"\"thumbs up\" used to mean \"seal the business transaction,\" and more recently meant \"good job/I approve/things are good,\" and now also means \"I want a ride.\" (and interestingly has been retconned incorrectly as the symbol ancient Romans used to signify that they wanted a gl... | [
"Quite recent, as it happens. It used to mean sexual excitation/flirtation. ",
"Shakespeare's Rape of Lucrece poem has a passage in which the main character is \"rolling his greedy eyeballs in his head\" at the thought of having sex with the woman he's pursuing. ",
"http://www.shakespeareswords.com/The-Rape-of-... | [
"In the course of human history, Shakespeare is fairly recent and certainly would suggest that eye rolling to express annoyance is not an evolutionary thing. ",
"But if you want a more recent example, in 1950 Hank Penny released a song called \"Bloodshot Eyes\" in which a former lover tries to woo the singer back... |
[
"If 'warm air is able to hold more moisture' is a myth, how do you then define relative humidity?"
] | [
false
] | So I teach high school science. I mostly teach physics, but also teach Earth Science. I've seen it said that the idea that warm air is able to hold more water before becoming saturated is a myth. However, relative humidity is defined as the amount of water held by the air as a percentage of the amount it can hold at a ... | [
"The main misconception is the notion that \"air holds water\". It doesn't. The dynamics of evaporation and humidity would be very similar if the air was sucked out and replaced by a vacuum.",
"So what happens?",
"Water molecules in liquid form move around with varying kinetic energies and therefore varying spe... | [
"It honestly sounds like you are describing the mechanism for why 'warm air holds more water', not proving that statement wrong at all.",
"I think the central point is one of semantics. The air itself isn't holding the water. Rather, higher temperatures allow for a higher partial pressure of gaseous water to exis... | [
"It honestly sounds like you are describing the mechanism for why 'warm air holds more water', not proving that statement wrong at all.",
"Well you first have to understand that water vapour isn't ",
". Water vapour exists in the same volume as air. The air itself has less to do with anything than the volume, p... |
[
"Can a shot of adrenaline to your heart (pulp fiction style) buy me a minute of consciousness when I'm bleeding to death?"
] | [
false
] | Say I'm a combat medic and I've just sustained multiple gunshot wounds. I know that my wounds are fatal and that I will die. However, I need a minute in order to complete my objective (say push a button that's twenty meters away). So before the darkness clouding around my vision turns into infinite night, I stab my hea... | [
"Assuming that the gunshots didn't hit anything major, I'd say yes.",
"But of course, the answer heavily depends on how many gunshots and where they are."
] | [
"well, vital organs is vague, everything in your body is an organ..and its all pretty important.",
"But from my understanding a single gunshot is enough to take a limp out of commission, none of that movie shit where the protagonist can walk miles with 5 bullet holes (not to say this can't happen, generally speak... | [
"Let's assume that there are 6 gunshot wounds but no vital organs or major arteries. "
] |
[
"Why don't we give many antibiotics at once to stop antibiotic resistance?"
] | [
false
] | [deleted] | [
"I think it is more about people not taking the antibiotics (or medication prescribed) seriously than it is about the bacterium being lucky. If you skip a dosage, you are possibly providing a sub-lethal dose of the antibiotic to the bacterium, giving a chance to the bacterium to develop defense tactics against the ... | [
"Antibiotic resistance is only sometimes due to a rare point mutation. More often it is a general anti-toxic mechnism, for example a pump getting rid of everything that could be potentially poisonous. What is more those mechanisms rarely occur one at a time - a resistant bacterium often carries a few of those.",
... | [
"You are right saying that resistance is more of our fault than bacteria getting lucky. It was shown that bacteria exposed to sub-lethal doses of antibiotics gain resistance and become fitter, so in the end they are not killed by what is a lethal dose for a control group."
] |
[
"Seeing as it is Ramadan and all right now. I have always been curious are there any medical benefits to fasting?"
] | [
false
] | In case you didn't know. Fasting in Islam requires no food or water from sunrise to sunset. | [
"Can you explain the detoxing effect? I've heard that detox diets are a hoax."
] | [
"Can you explain the detoxing effect? I've heard that detox diets are a hoax."
] | [
"A very knowledgeable chemistry professor gave me this argument when I was an undergrad. I respect this professor, and he was enlightening in many ways, but I do not claim in anyway that the following statements and arguments are backed up by any science.",
"His argument was that when you fast, your body is force... |
[
"How efficient is chlorophyll in converting sunlight to energy compared to our best solar cells? If it is more efficient, why don't we copy what those cells do in designing new solar cells?"
] | [
false
] | Presumably we know how plants convert sunlight to energy, so I was wondering if they do so more efficiently than we do with solar cells. Then I got to wondering that if they do, why we don't have some type of artificial chlorophyll that we could use for solar energy. | [
"Presumably we know how plants convert sunlight to energy,",
"Plants convert solar energy into chemical energy with an efficiency around 3-6% depending on the species and other environment factors. Generally, our problem is that this chemical energy is not readily useful to us unless we first convert it into ther... | [
"A problem here is that you're conflating two different processes. Simplistically, what is happening in the case of a solar cell is:",
"1) Photon hits optically active (in IR/visible/UV range) inorganic chemical compound leading to atomic/molecular excitation",
"2) Eventually this excitation leads to the libera... | [
"The most amazing part about chlorophyll - it's an organometallic complex nature came up with all on it's own! And it's easily reproducible by cells! Thousands of tons are produced every day. If only it were that easy for us to make solar cells. ",
"Plants can also bind carbon dioxide (albeit in a different p... |
[
"Sun's rays question"
] | [
false
] | Well we all know the harmful effecrs of our own Sun's rays. (Ie. Radiation.) There are trillions of stars out there, a lot being bigger than our own. Do these stars have the same effect as ours on earth? Do they also create radiation for earth or are they too far to contribute anything other than the very distant light... | [
"Their radiation also hits us, but its nowhere near the magnitude of what we receive from the sun."
] | [
"Not much. Look at how small and dim stars are. Whereas if you look at the sun, you could go blind. That shows just how much more intense the radiation from the sun is compared to stars. Light from other stars is minuscule at best."
] | [
"I'd like to also ask, do these distant stars also contribute to say solar energy?"
] |
[
"What's going on with all of those sub-atomic particles?"
] | [
false
] | [deleted] | [
"I'll give you a bit of an overview.",
"The fundamental particles we know about are divided into two types: Fermions and bosons. Loosely speaking, fermions represent matter particles and bosons come from the forces between the fermions.",
"The bosons are:\n(Electroweak bosons):",
"W boson",
"Z boson",
"Ph... | [
"You are mixing apples and oranges. :) Some of those are particles, some are groups of particles.",
"To explain 99% of the universe, all you need is protons, neutrons, and electrons (plus photons). Everything else is detail and special cases.",
"But, the ones that you mentioned:",
"In fact, outside of proto... | [
"There are six kinds of quark: top, bottom, strange, charm, top, bottom. Before they realized that a lot of particles are made out of quarks, they thought each new particle they discovered was a new fundamental one. Protons are made of three (up up down) as are neutrons (up down down). Strange and charm are way big... |
[
"Why are there spiral galaxies?"
] | [
false
] | Shouldn't they all be elliptical because objects orbiting closer to the center of the galaxy move faster and pass up the stars on the end of an arm. | [
"Most galaxies are formed as disks out of massive gas clouds. These gas clouds have some angular momentum (asking why they are endowed with some spin is a whole other question, one that is be happy to answer...). As the gas cools through a process called \"atomic line cooling\", the gas generally doesn't want to lo... | [
"Yes they certainly will reconfigure. The stars in the galaxy are also bobbing up and down and bobbing inwards and outwards. Additionally the galaxy will suck in more material and grow; the addition of more material will also change the pattern speed and size of the spiral arms. "
] | [
"The thickness (known as the scale height) of a disk Galaxy is a continuum from the thinnest flattest ones to fat ellipsoidal things that don't look much like disks at all. For the Milky Way we recently discovered that there are two disks superimposed if you divide the stars by age: a thin (young star) disk and a t... |
[
"space radiation"
] | [
false
] | What kinds of advances have been made in absorbing space radiation in spacecraft and spacesuits? My understanding is that carbon is super useful for that. Does carbon fiber absorb radiation? How does this work? | [
"I'm not sure about what is done to prevent radiation harm to astronauts, but I design the electronics that go into spacecraft and all of the parts we use were designed to be radiation hardened, both in terms of architecture and fabrication. Everything undergoes rigorous analysis to show that the upset rates and la... | [
"how do you radiation harden your stuff? what's the material used?"
] | [
"There is actually a good summary on the wikipedia page that says it better than I can: ",
"http://en.wikipedia.org/wiki/Radiation_hardening"
] |
[
"Can a moon have its own moon, or does the gravitational pull from the planet override the moons?"
] | [
false
] | title says it all. | [
"Sure. After all, the planets in the solar system all orbit the sun, but many of them have moons orbiting them without the gravity from the sun messing everything up. No reason you couldn't go another layer down and have something orbiting a moon."
] | [
"Hasn't been observed yet, but not out of the realm of possibilities. If you think about it, the earth is one of the suns moons, saying that the sun is a moon of the galactic core might be a stretch though. ",
"First result on google search of \"moon of a moon\", says it better than I could."
] | [
"Wikipedia's page on natural satellite",
" discusses this -- not yet observed, possible though unlikely, and maybe soon-to-be observed.",
"Also, further into the article is a short discussion on what natural satellites count as \"moons\", etc. "
] |
[
"How would you find the theoretical temperature of a system?"
] | [
false
] | null | [
"You can using thermodynamics and calorimetry, but some of the details are not straight-forward (at least to some). I would approach the problem like this in a mathematical sense:",
"-q(room air) = q(N2) + dHvap(N2) + dH(N2 for -200(deg)C to -195.8(deg)C)",
"This assumes energy is conserved and stays in the roo... | [
"Alright I know this was a month ago, but I'm curios to see if there's a realistic way to find a theoretical temperature of the ",
"Nether",
" Using thermochem and calorimetry"
] | [
"This is an interesting questions, considering I've played more Minecraft than I care to admit over the past few years. I'll give it some thought over the next little while and get back to you with what I come up with :)"
] |
[
"why does noise get quieter when we yawn?"
] | [
false
] | [deleted] | [
"Yawning activates a small muscle called the tensor tympani. This muscle is connected to your ear drum and increases the tension on it. With increased tension, the ear drum is less mobile and therefore less responsive to vibrations (sound). The end result being that sounds are perceived as dampened. Some people can... | [
"I didn’t know ear rumbling isn’t something everyone can do. Not that it matters.",
"edit: ear, duh"
] | [
"Not me purposefully ear rumbling to test if it dampens sound and then realizing that not everyone could do that..."
] |
[
"Can animals be afraid of an item which represents a predator they have no point of reference for?"
] | [
false
] | [deleted] | [
"Trauma and fear have been demonstrated to be heritable. That whole archaic nature vs nurture division is looking rather blurry considering this, and epigenetics. ",
"https://www.washingtonpost.com/national/health-science/study-finds-that-fear-can-travel-quickly-through-generations-of-mice-dna/2013/12/07/94dc97f... | [
"I was a chicken farmer for a long time for Sanderson farms. Chickens raised in chicken houses are scared of flashlights because it produces a shadow that makes them think it's a hawk.. they will run away and pile up on each other.. sometimes suffocating one another... these chickens were hatched inside and raised ... | [
"I’m not so sure the reason that the cats were afraid of the cucumbers was because they thought that it they were snakes but because it was something large that was not there a moment ago I think that the cucumber can be replaced with any item of equal size and the reaction would be the same. "
] |
[
"Were plants larger or smaller on earth two hundred million years ago as compared to today?"
] | [
false
] | I've heard a lot about how dinosaurs where able to grow very large due to the high oxygen levels at the time, did this mean that prehistoric plants were smaller back then from the lack of carbon dioxide? And how would the extinction event impact plant sizes? | [
"Just to correct a misconception: we do not have evidence that dinosaurs were larger because of higher oxygen levels. We have a ",
"number of posts in our FAQ",
" about this that go into details."
] | [
"Excellent, then you're doing science right! I can try to answer them later today. I'm not an expert on fossil plants, unfortunately. I know we have some invertebrate paleontologists, and while inverts are also not plants, they may have a better baseline of knowledge on this subject than I.",
"Edit: I'd start wit... | [
"Thank you for the correction, but now I have even more questions."
] |
[
"When two protons collide and break apart, what force is actually causing them to break apart?"
] | [
false
] | So one of the shocking things I remember learning physics, is that solid matter never actually collides or touches. The electromagnetic force actually repels molecules from actually touching each other. So when one thing collides into another, its actually the electromagnetic force that rips it apart. But this got me t... | [
"In a particle accelerator, we're giving these protons enough energy to get close enough together that their constituent particles (quarks and gluons) can interact via the strong and weak forces, which have very short ranges.",
"That being said, the EM force also plays a role in that.",
"When they interact, the... | [
"Well, at this level, we don't even really think about binding energies or changes in mass anymore. You'll likely get a giant spray of particles coming out of the collision, not a couple discrete products, so thinking about things in those terms isn't that useful to us (while it is very useful for, say, nuclear ph... | [
"Glukkake FTW.",
"But in all seriousness... Aren't even the various \"forces\" just shorthand for the weirdnesses of particle interaction? As I understand it, we represent the \"force carriers\" with so-called \"virtual particles\", basically meaning that \"It's ",
" a particle, just not\", and that it's only ... |
[
"Does Buoyancy Exist?"
] | [
false
] | null | [
"Your observations are astute. \"Buoyant force\" is indeed a fictitious force used to describe the difference in apparent weight of an object immersed in fluid. It does not exist without gravity. As for your second question about gases and surface tension, the answer is no."
] | [
"Buoyant force is as real as centrifugal force! :)"
] | [
"Just to add something to the discussion, here is a video about air bubbles in water in space! ",
"http://www.youtube.com/watch?v=cXsvy2tBJlU",
"The surface tension of the water keeps the bubble inside."
] |
[
"How are chip manufacturers getting around quantum tunneling in the manufacturing of smaller than 7nm sized chips?"
] | [
false
] | So we all know that quantum tunneling was going to be an issue down at the smallest transistor size levels, where 7nm was claimed to be the absolute limit. But now I'm seeing 7nm processes everywhere in my phone, in the CPU I'm using in my machine, and from what I'm reading Samsung and TSMC have manufactured 5nm proces... | [
"They're not getting around it. But also, they kind of are.",
"First though, \"5nm\", \"3nm\" and so on are just marketing names. There is nothing about \"5nm\" that makes it \"5nm\" other than the company in question saying it is. Some things are smaller than 5nm on a given 5nm node, and some are larger. I canno... | [
"Well someone can explain this better but the names hardly refer to any feature size and hasn’t for awhile. They used to refer to the pitch or how I understand the space between two logic gates. Intels pitch was 70nm for 14nm and tsmc pitch was 80nm at 14nm.",
"Even then, they do face quantum tunneling and to fig... | [
"The main leakage path for quantum tunneling is through the very thin layer of insulator separating the transistor channel and the gate contact (see ",
"this video",
" for a discussion of a lot of these issues). The insulating material we use for this was silicon dioxide because it was very easy to grow on a si... |
[
"How does the security on a phone compare to the security on a computer, assuming both are using top-level technologies?"
] | [
false
] | null | [
"You know, I'm pretty close to just unsubscribing because of the mod team. Let people ask their questions, and leave the \"vagueness\" up to the reader. Stop filtering good questions. "
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"For more information regarding this and similar issues, please see our ",
"guidelines.",
"If you disagree with this decision, please send a ",
"message to the moderators."
] | [
"Your question does not refer to a single measurable quantity, as you seem to think security is, nor a use case, scenario, or threat model. It's not possible to answer such a query without either addressing all of them or making assumptions about what you wanted to ask, which is in both cases counterproductive and ... |
[
"Looking for a citation web visualization tool (or something)"
] | [
false
] | So, let's say I have a bunch of articles, and I want to see how they interconnect, specifically what cites what. Is there some tool where I can plug in my citations, and it will look up the article on google scholar or some such, and make a web showing which articles cite what? Bonus points for showing relative dista... | [
"One of my colleagues is working on creating an expert recommender system on a problem similar to this. He's working on creating a system that, given a set of articles, finds ",
" additional articles that are relevant and interesting to the articles provided, based currently on the citation network.",
"Based on... | [
"Cool, I will try those; but as for the semantic recommendation thing, I don't think I need anything as elaborate as that; really, I'm just looking for a good way to organize the articles I already have. I have a bunch loaded into Zotero, but keeping track of what cites what gets difficult once you hit 30 articles... | [
"On a practical level, you could try manually tagging articles with the articles they cite. For instance, if you have an citation like the following:",
"[1] H. Benko, \"Beyond flat surface computing: challenges of depth-aware and curved interfaces\", ",
", 2009.",
"You could decide to give a tag to citing a... |
[
"Is there any correlation between skin colour and body heat (and heat retention)?"
] | [
false
] | I'm convinced that there is! My girlfriend was born in England. She gets cold much quicker than I do and finds it hard to retain body heat. I on the other hand have a middle eastern background and am warm skinned most of the time (and don't get cold as easily as she does), I'm olive skinned and she is white skinned. No... | [
"Early humans in the tropics probably developed dark skin to block out the sun and protect their body's folate reserves, which decreases with increased UV exposure. Early humans further from the equator probably developed fair skin to drink in the UV rays in order to make enough vitamin D to survive. As far as heat... | [
"The issue of skin surface area is related to body proportions, right?I read somewhere that people from warm climates tend to be more limb-y and less torso-y."
] | [
"yep.. eskimos short and stocky, africans tall and lanky"
] |
[
"Why does my glass of water get a bunch of bubbles clinging to the glass after I leave it out for a few days?"
] | [
false
] | null | [
"It doesn't have to be days, 3-4 hours can be enough.\nMy understanding is the colder water from the faucet contains an amout of oxygen which comes out of solution as the temperature rises to room temp.\nGuess it could be tested with a bottle of tap water placed in a fridge."
] | [
"Generally it is the gasses of the environment disolving in the water (see below). It can also be some of the hydrogen or oxygen coming out of solution due to an unbalanced state (equilibruim-wise).",
"Atmospheric gases such as nitrogen and oxygen can dissolve in water. The amount of gas dissolved depends on the ... | [
"That could be true, but most of the time it is not. I'm fairly certain to produce the amount of bubbles seen in the glass, your cultures would need to be visable to the human eye. <--100% assumption based"
] |
[
"Is it possible with unlimited fuel to reach the speed of light in space? Or is there a maximum speed that can be reached?"
] | [
false
] | null | [
"You can asymptotically approach c, but never reach it. With unlimited fuel, you can travel at 99.9999999999999999999% of c, but you’ll never reach c itself. You’ll also move into the realm of insane time dilation, so by the time you get back to Earth the Sun will probably have long since burned out. "
] | [
"No massive object can travel at the speed of light. In principle, with enough fuel, any speed less than ",
" (with respect to Earth) is attainable."
] | [
"You're already travelling close to c relative to a cosmic ray anyway. Speeds mean very little without frames of reference."
] |
[
"If a supernova from a star was racing toward us, would we know before it hit us?"
] | [
false
] | null | [
"Sun won't go supernova, it'll turn into a red giant, expel its atmosphere as a planetary nebula, and a white dwarf will remain."
] | [
"It depends on the type of supernova. A type II supernova releases a burst of neutrinos a few hours before the light leaves the explosion so if you have a neutrino detector you would be alerted a few hours before you see the light from the supernova. In fact, there's a website that will send you an email if such a ... | [
"Ah right, I'm sure I knew this.. Should really try finishing a thought before trying to be a 'smart-ass'. Going back to my hole now!"
] |
[
"How to generate electricity from scratch?"
] | [
false
] | Assume I wake up in pre-industrial civilization with only my clothes and everything I've got on myself. Past sucks, so I want to rebuild modern society as soon as possible. Unfortunately I'm just regular guy, I hardly know how any of the technology I use works, I could give locals some good ideas, but nothing radical. ... | [
"The most important thing to know is to be familiar with ",
"Lenz's law",
": The changing magnetic flux through a loop of wire is proportional to the amount of \"voltage\" produced in the wire. So you get yourself a coil of wire and a magnet, and maybe a water wheel, and you've got yourself a generator. Of cour... | [
"Yeah If I find myself dropped back into pre-industrial Hawaii.... I think I'm going to just let it be and enjoy myself."
] | [
"You could also ",
"build a homemade solar cell"
] |
[
"Why does rain fall in drops and not as one mass of water?"
] | [
false
] | [deleted] | [
"Three main reasons:",
"1) Once a droplet reaches a certain size it starts falling, so there's limited time for a droplet to grow and merge with other droplets. There are some environmental properties which cause droplets to vary in size, but they can't grow indefinitely.",
"2) The water is spread across a larg... | [
"When invisible water vapor condenses on particles of dust, it becomes visible as a cloud. When enough water vapor has condensed on a given particle to make it too heavy to float in the air, it will fall as a rain drop. Because these drops are formed individually, they act individually as rain drops."
] | [
"This could also be related to Plateau-Rayleigh instability. The premise if that small perturbations are always present, and that the faster growing perturbations eventually cause the liquid to break apart in some situations.",
"http://en.wikipedia.org/wiki/Plateau%E2%80%93Rayleigh_instability"
] |
[
"What commodities are we going to run out of in the next x decades? What alternatives exist for these?"
] | [
false
] | null | [
"I am looking for research based answers from research based people in their respective fields.",
"How is this not relevant?"
] | [
"To be fair, this is a very specific question. Finite commodities. Nothing complex. ",
"I want to maximise the best chances at getting good answer. Please reconsider letting my question through. Suppressing questions doesn't help anyone, especially when they are good ones like mine. This question has never been b... | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"For more information regarding this and similar issues, please see our ",
"guidelines.",
"/r/AskScienceDiscussion",
"Please see our ",
"guidelines.",
"If you disagree with this decision, pleas... |
[
"How can we measure the universe's age in years?"
] | [
false
] | If years are a measurement of earth's revolution around the sun, and we (I guess "we" here can be extended to complex life) have only been "aware" of time for ~2 billion years (taking half the , how can we possibly measure the age of the universe in the same way that we measure earth time? For that matter, since we hum... | [
"If years are a measurement of earth's revolution around the sun, and we (I guess \"we\" here can be extended to complex life) have only been \"aware\" of time for ~2 billion years (taking half the , how can we possibly measure the age of the universe in the same way that we measure earth time?",
"A year can also... | [
"For any observer who is at rest relative to the cosmic microwave background, the age of the universe will appear the same. And no, time is not altered by the density of the universe, since gravitational time dilation happens from the ",
" of spacetime rather than merely the density. So it's more about how uneven... | [
"When we say \"rest frame of the CMB,\" we mean a frame in which it looks as isotropic as possible. If you just look at it standing on Earth, you'll get a large extraneous asymmetric Doppler shift signal due to the motion and rotation of the Earth, Sun, and Milky Way relative to this frame. The CMB maps you see f... |
[
"How did eukaryotes evolve?"
] | [
false
] | Or at least, what are the prevailing hypotheses? | [
"The ",
"endosymbiont theory",
" is the one that gets the most traction, and is probably correct. ",
"Basically, some early prokaryote took on a parasitic lifestyle; living inside and off of another, larger prokaryote. Over time, this developed in to a symbiotic relationship, the former parasite not just livi... | [
"On a related note, the ",
"Hatena arenicola",
" is an example of how chloroplasts probably evolved in eukaryotes through endosymbiosis. Hatena actually starts out as a heterotroph and eventually injests an algae cell but instead of completely breaking down the algae cell, Hatena retains the chloroplast organel... | [
"Awesome, thank you. "
] |
[
"Does water evaporate faster if it is mixed with alcohol?"
] | [
false
] | Title is pretty self-explanatory. Was wondering if a mixture of alcohol and water were to evaporate (I am aware that the alcohol will evaporate much faster), but would this have any effect on the evaporation rate of the water itself as well? Reason is because I made a cheesecake and accidentally got the crust soggy. I ... | [
"Alcohol-water mixtures do evaporate faster than pure water. That said, spraying alcohol on food will likely cause other problems -- for example, the alcohol may partially dissolve some oils or fats and change the texture of the food."
] | [
"Technically, yes. This is done all the time, especially when cleaning things with small crevices, such as toys or electronics. ",
"However. ",
"Everclear also has other things in it, such as sugar. I know nothing about baking and I have no idea what kind of side effects you might have. ",
"But yes, alcohol w... | [
"Thanks for the reply man, you've confirmed my intuition. It did end up turning out just fine by the way, no alcohol needed"
] |
[
"What did Carl Sagan mean when he said, \"If you wish to make an apple pie from scratch you must first invent the universe\"?"
] | [
false
] | null | [
"In any creation project, you have to get something from someone else. A pie needs flour. If you want to make your own flour, you'll need wheat, and milling equipment. To get that, you'll need farms and metal, which needs soil and minerals. To truly say you made it, you'd have to make the dirt and minerals. To make... | [
"I understand it as a particular perspective on what \"from scratch\" means. Sort of a reductio ad absurdum, but it's less of an argument and more of an observation. Basically, if you take \"from scratch\" to enough of an extreme you can take it all the way back to the Big Bang. "
] | [
"This will get downvoted, but you're an asshole along with the 9 people who (at the moment) have upvoted you. The strict posting rules should be to prevent the influx of jokes and immaturities, not to eradicate kind behavior. It's a harmless comment (inexplicably downvoted) which doesn't detract from the conversati... |
[
"Does gravity still 'work' when scaled down?"
] | [
false
] | [deleted] | [
"Small, yes, but theoretically possible.\nGiven an orbital radius, of 1m, the above calculated gravitational attraction force of 7.5x10-15 N, we can calculate the required speed for this orbit to be viable (ie no decay or orbital enlargement) from the equation for centripetal acceleration, a=v",
"/r, and Newton's... | [
"Small, yes, but theoretically possible.\nGiven an orbital radius, of 1m, the above calculated gravitational attraction force of 7.5x10-15 N, we can calculate the required speed for this orbit to be viable (ie no decay or orbital enlargement) from the equation for centripetal acceleration, a=v",
"/r, and Newton's... | [
"Small, yes, but theoretically possible.\nGiven an orbital radius, of 1m, the above calculated gravitational attraction force of 7.5x10-15 N, we can calculate the required speed for this orbit to be viable (ie no decay or orbital enlargement) from the equation for centripetal acceleration, a=v",
"/r, and Newton's... |
[
"How do small birds survive sub zero temperatures with such little body mass?"
] | [
false
] | I understand the concept of hollow, thus insulating, feathers, but it just amazes me that these little creatures are still flying about. It's been below zero for several days where I live. Their bodies are so small, they cannot possibly produce much heat. | [
"MS in biology here...not sure about that specific species of bird, but usually keeping warm is going to involve a few things, 1) maintaining body heat through the expenditure of energy, so metabolism needs to be supported by adequate food consumption, and 2) preserving that body heat through insulation such as fat... | [
"Very good explanation. Birds need to find a lot of food during the winter (which is why bird feeders are so busy) to keep their temperatures up. I band birds in my spare time, and we're not allowed to use mist nets (fine nets that catch birds in flight) for catching in the winter because it restricts their movemen... | [
"Don't forget about ",
"torpor",
"! Hummingbirds are the most well known for going into a torpid state overnight, but many other birds can do it too. And some can do it for even longer, the longest known being the Common Poorwill (88 days!)."
] |
[
"Why are some illnesses more (or less) serious to adults than to children?"
] | [
false
] | Chickenpox, mumps ect. Why are they less serious in kids, but potentially fatal in adults. Equally why are some things trivial to adults, but serious in children? | [
"Sometimes it is the immune response itself, being stronger in adults, that can cause fatality. An apposite example is \"cytokine storm\" with respect to influenza outbreaks - it is the case that the young are more susceptible to having a stronger immune response (positive feedback loop where cells are stimulated t... | [
"It is because Children and adults have fundamentally different biological systems at play. Children are not small adult s but unique in their own right, they have weaker immune systems at a very early age which makes them susceptible to infection but less susceptible to immune mediated damage e.g. Hepatitis B (no ... | [
"Complications make some illnesses more serious to adults than to children. Adult chickenpox can lead to serious complications if pneumonia (which is more serious with adults) occurs and mumps in adults is often associated with meningitis and encephalitis, which isn't as common with mumps in children. Some illnesse... |
[
"How much damage would a sudden reversal of the magnetic poles do?"
] | [
false
] | My (somewhat paranoid) sister says that the 2012 apocalypse will happen when the solar system lines up with the galactic core and reverse Earth's magnetic poles. I was wondering how much damage a sudden reversal of the poles would do. | [
"There is an easy experiment you can do at home to assuage your concerns about what impact a magnetic pole reversal may have on modern-day technology:",
"1) Take a laptop or smartphone or other piece of tech and place it in front of you. ",
"2) Next, pick it up and rotate it 180°. ",
"Congratulations, your te... | [
"That was literally the best explanation for anything I've ever heard."
] | [
"Polar reversals are not really sudden the way most people would think of them. They happen over the course of anywhere from 1,000 to 10,000 years, so they just seem instantaneous on a geological time scale. It is actually quite possible that one is occurring now, as the poles have moved a fairly significant distan... |
[
"Are there any \"one-way\" membranes?"
] | [
false
] | Basically I'm just curious if there are any materials that will allow liquids through, but only in one direction. | [
"Cells have membranes that only allow things to pass one way. This could be something as small as protons passing through a pump or something as large as kilobases of mRNA going through the nuclear pore complex. But active transport across these membranes requires a source of free energy (like GTP or sunlight), bec... | [
"Such a membrane would violate the second law of thermodynamics, unless it was externally powered or needed a pressure differential to work (like a valve).",
"Thought experiment: take a pool of water and divide it in two with a wall of this membrane. The water will flow through random motion all to one side, decr... | [
"So, no chance for the Gungan city to exist?"
] |
[
"Why does all garbage smell roughly the same?"
] | [
false
] | [deleted] | [
"This doesn't really answer OP's question. If garbage all smells the same because it's harboring the same disease, that just raises the question of why does it all harbor the same disease?"
] | [
"And why doesnt garbage composed of different material smell wildly different? "
] | [
"The reason our nose is located above our mouth is presumably so that we don't ingest things which our body can't process as food, or which eventually kill us. One of the things that kill humans is disease. Our sense of smell has evolved to associate things harboring disease with a very bad smell (e.g. excrement)... |
[
"Does tectonic activity contribute to sea level changes?"
] | [
false
] | There is an article on front page right now about how Antarctica is actually gaining ice(more specifically increasing in elevation) more than it is shedding ice. When we try to quantify sea level fluctuations, is tectonic activity taken into account? | [
"Tectonic activity can certainly affect sea level. It depends mostly on the speed at which the plates move, which in turn affects the age of the material on the plates. Consider that at a divergent plate boundary, material is being added to the plate. This fresh material is hotter and less dense. Because the plate ... | [
"I doubt it. Tectonic movement is generally a very slow process, and the change in rate is likely even slower. Sea level changes with tectonic sources are processes that take millions of years. Actually, tectonic activity isn't part of climate, so by definition, it would not be factored in, I should think."
] | [
"The two principle factors that control eustatic (global) sea level are tectonics and glaciations. Tectonics are not entirely independent of climate, although climate change activists fear the melting of glaciers and the resultant sea-level rise mostly. As glaciers melt from the continents, however, a process known... |
[
"What is the time uncertainty in the energy time uncertainty principle? How can we derive this from position and momentum uncertainty? How to calculate it since we do not have an operator for time?"
] | [
false
] | null | [
"This",
" is my favorite explanation of the time-energy uncertainty relation. The gist of it is:",
"the \"uncertainty\" in time is expressed as the average time taken, starting in state ψ, for the expectation of some arbitrary operator A to change by its standard deviation.",
"You're not using t since, as you... | [
"The time uncertainty is the lifetime of an unstable state, and the energy uncertainty is the intrinsic linewidth (full width at half maximum) of the state.",
"This is independent of the position-momentum uncertainty relation."
] | [
"By that logic there is no space because the only way an observer knows if space extends is if something is where the observer is not. He can only know that however if something moves from there to here."
] |
[
"Which of a nuclear explosion's effects are unique to it being nuclear?"
] | [
false
] | Radiation and fallout are obviously due to the radioactive fuel source, but what about things like the flash or mushroom cloud? How many of, say, Little Boy's effects could be replicated with 12,000 tons of conventional explosives? | [
"Mushroom clouds are not unique to nuclear explosions, it’s just a result of fluid-dynamical instabilities (Rayleigh-Taylor, and subsequently Kelvin-Helmholtz). If you put a denser fluid above a less dense fluid (including fluids of the same composition, but with a downward temperature gradient) buoyancy drives any... | [
"The specific feature unique to nuclear explosions in atmosphere is the double flash - essentially the explosion generates a bright flash which is briefly dimmed by the shockwave passing through it, before brightening up again... this does not happen with conventional explosives, so much so that detecting the doubl... | [
"The time it takes for the detonation wave to propagate across a volume of 20 kt of conventional HE is maybe ~ milliseconds, while the energy release of a nuclear weapon happens on a faster timescale.",
"But what's more important is the temperature produced, because that determines the thermal radiation (and ener... |
[
"Would the Hubble be able to take a picture of the James Webb and Vice Versa?"
] | [
false
] | Question... | [
"JWST (James Webb Space Telescope) will be all the way out at the L2 Lagrange point, which is about 1.5 million km from Earth. HST (Hubble Space Telescope) is in low earth orbit, only like 500 km up, so from anywhere in HST's orbit, JWST will still be about 1.5 million km away.",
"The L2 Lagrange point is permane... | [
"Without Earth, at that distance to the Sun an orbit would need to take longer than one year because it's a bit farther away from the Sun. Earth provides the necessary additional gravity to keep a spacecraft in a one-year orbit at L2."
] | [
"Side tangent since you seem like a smart person able to explain things: I do not understand how the L2 point works. How is there gravitational equilibrium there when it's not between the Earth and the Sun?"
] |
[
"Climate Change"
] | [
false
] | Can some explain in detail how the increase in CO2 leads to climate change? I've always understood it on the surface, but not the details. I want to be able to counter argue opposite talking points such as found here Thanks | [
"The Wikipedia article on the ",
"greenhouse effect",
" is a good starting point. ",
"The basic idea is that the hotter an object is, the faster it loses heat through thermal radiation. The earth is in a state of equilibrium where it loses heat at the same average rate at which it receives energy from the sun... | [
"Follow the energy:",
"The Sun radiates like a blackbody with a 6000 Kelvin effective temperature, so it's peak wavelength is ~ 500 nm (i.e green light). Some of this radiation gets radiated in the direction of Earth. It so happens that there's not much in the Earth's atmosphere which absorbs at these wavelengths... | [
"Thank You.",
"This does a great job of explaining the effect."
] |
[
"Since all life shares a common ancestor at some point, how 'related' might I be to a chimpanzee, in the traditional sense? (Could a chimp be my ten thousandth cousin? My hundred thousandth?)"
] | [
false
] | I was thinking about how the tree of life is like a really big family tree and it brought me to this question. | [
"The last common ancestor of humans and chimpanzees is estimated at ",
"5-10 million years ago",
" and ",
"average generation length",
" = 15-30 years",
"Using those numbers ~166666 to 666666 generations back...",
"So nth cousins share a n+1 common ancestor.",
"Somewhere between 166665th cousins and 6... | [
"The most recent common ancestor between humans and chimpanzees is estimated to have been around 6 million years ago. Assuming a generation time of 20 years (may be off somewhat but it's good enough for Fermi), that would be about 300,000 generations ago. I think that means that chimps are our 300,000th cousins, gi... | [
"Once two branches have diverged, any inbreeding within either branch doesn't matter for the most recent common ancestor."
] |
[
"How does Shotgun sequencing work?"
] | [
false
] | If the genome is broken by restriction enzymes, how can they be computationally put in order? The way I was thinking about it was "they are broken into puzzle pieces and reassembled by the computer" . However, this doesn't make sense to me for two reasons: 1) Wouldn't they have the same ends, so it would be impossib... | [
"With shotgun, what you get out is just contigs, not chromosomes.",
"Contigs vary from a few kilobase to millions of kb, depending on genome architecture. ",
"Assembly algorithms are based on homology, so as long there is sufficient variation to uniquely map individual 20-200bp reads (length depending on the te... | [
"Going to try and use layman's terms here.",
"You go to the store and buy 100,000 of the same 1,000-piece puzzle of a ship on the sea. You complete each of the puzzles, and randomly smear glue over parts of each completed puzzle. Then you shuffle everything up, breaking apart any pieces that aren't glued together... | [
"Well, to get the draft of a genome, sequencing is just the first step of the process. ",
"What you get with shotgun sequencing is a lot of fragments of some genome. These are called \"reads\", and their size may vary according to the technology used (454, Illumina, etc.). ",
"The next step is \"assembly\", and... |
[
"Can a spaceship descend slow enough to Earth that it wouldn’t encounter the intense heat generated upon reentry?"
] | [
false
] | If a craft was able to decelerate to a slow enough speed, could it gently fall back to earth using vector rockets (or something) and main thrust to keep the descent slow enough or would it be unable to punch through the Earth’s atmosphere? Less heat and constant radio communication are cool, right? (Pun intended). | [
"Yes it could. But that would require about as much propellant as what is used to launch the rocket in the first place so it's not really practical. "
] | [
"In principle, yes. The reason we don't do this is that it means that we get the deceleration \"for free\". Instead of having to use a huge amount of fuel to slow yourself down and gently land, you can use the atmosphere to aerobrake.",
"You would need to slow your speed down to zero, which means you need a rocke... | [
"Any way of reducing the tangential velocity would work. A highly spiraled entry (with fixed wings and a careful entry velocity) would work as well, but would be incredibly difficult and take a long time."
] |
[
"If an object reaches absolute zero does it lose all mass?"
] | [
false
] | null | [
"No, it still has its mass. Absolute zero doesn't imply an absence of energy, it just implies that they system has its ",
" energy. The minimum is not necessarily zero."
] | [
"A free particle can't have zero energy. A massive particle has a minimum energy of mc",
", and a massless particle must move at c in all frames of reference, so it must have nonzero momentum (p), and an energy E = pc."
] | [
"If something had zero energy would it then have zero mass?"
] |
[
"Why do we get the urge to throw up when we smell something bad?"
] | [
false
] | null | [
"I have no sources to back this up, but basically, if you eat something bad, you should throw it up, yes? So if you smell something bad, your body is reacting as if it might have contaminated anything you recently ate, and wants to get rid of it. "
] | [
"I figured something along those lines myself actually lol, just wasn't sure."
] | [
"I do not get this urge. "
] |
[
"How do kinetochore microtubuli take chromatides with them when depolymerising?"
] | [
false
] | So I know THAT it happens: kinetochore microtubuli bind to the kinetochores on the chromosome, then they start depolymerising and they take the chromatides with them. I can find all of this on the internet, what I can't find, however, is how it happens. Why does the chromatide go along with the depolymerising microtubu... | [
"If you can ",
"see this figure",
" I think it might help you understand. The kinetochore of the chromatid is not attached to the ",
" of the microtubule. It is attached a little further 'in', on the side of the microtubule. ",
"Imagine a rope with a ring loosely fitted ",
" one end, but not directly on t... | [
"There are motor proteins pulling on them called kinesin-related proteins (KRPs). There are many different types of KRPs with many different shapes. The simplest example I can think of is kinesin-5. It looks like ",
"two kinesins attached by their tail ends",
". For each pair of microtubules (MT), there'll be m... | [
"The kinetochores shorten at the plus end (the end attached to the chromatid) by depolymerization of the tubulin dimers that make up the microtubule (MT).",
"Due to the interactions of various microtubule associated proteins (MAPs), the microtubule stays attached to the kinetochore on the chromosome as the microt... |
[
"A quick question on information transfer speed within cables?"
] | [
false
] | I was having a quick browse on cnet today when I read that Singapore had released broadband out there with a 100Gb/s transfer speed, this got me thinking, with my broadband at home perhaps a short part of my connection is fibre optic but the majority of it is made from what I assume is copper cable? I'm studying theore... | [
"One electron \"pushes\" the next electron through the electromagnetic field, without needing to be right on top of it. The next electron then pushes another electron farther down in the same way. An electrical signal is not really carried by individual electrons. It is carried by the electromagnetic field, and sup... | [
"If the cable is capable of transfering higher frequencies, then the cable can support faster data transfer. But cables work as a damper for high frequencies and therefor the data transfer is limited. On the internet the data transfer rate is mostly limited by the switches and routers between two computers and othe... | [
"Really well explained thank you! So are higher frequency electrical signs capable of transferring more information, or is it the rate at which the frequency can be changed that determines the amount of information transferred? "
] |
[
"What are the effects of spontaneous decay of carbon-14 in genes?"
] | [
false
] | Carbon-14 spontaneously decay into Nitrogen-14 via beta radiation. As our genes contains carbon atoms, some of them should be carbon-14 isotopes and they would naturally decay into Nitrogen-14. So I was wondering what are the effects of replacing a carbon atom into a nitrogen atom in genes, and what might the beta part... | [
"Well, carbon is chemically different from nitrogen, so in most situations you couldn't swap out a carbon atom in a molecule for a nitrogen and have the bonds remain the same. Depending on its position, the nitrogen atom might pop out of the molecule, or eject one of the atoms beside it, or the molecule might break... | [
"Oh OK. So the body will probably repair it, or it won't spread through the body.",
"There goes my hope of an X-men mutation!",
"THX for the answer ☺️"
] | [
"Well, put it this way, if a mutation does occur that gives you* a cool new ability - this is extremely unlikely, but it does happen occasionally, which is how evolution gets its raw material, as it were - carbon-14 decay ",
" one way this mutation can happen. I was primarily trying to explain that a carbon-14-in... |
[
"Could this be a form of synesthesia?"
] | [
false
] | came up in DAE a few days ago, and I thought I'd pose it to the experts.... If I hear a sharp, sudden noise when I'm half-asleep (car door slamming, door banging, one of our fatass cats belly-flopping off the windowsill, etc), I get a quick flash of brightness/static behind closed eyes to "accompany" it. Would this be ... | [
"I get the same thing, and it appears to be a somewhat common byproduct of ",
"hypnagogia",
".",
"Sometimes there is synesthesia; many people report seeing a flash of light or some other visual image in response to a real sound. "
] | [
"Good to know! I totally got this when my TV used to give a little \"bang\" from discharging itself."
] | [
"To be synesthesia, I believe it must be consistent."
] |
[
"Has there been any actual research into the claim that shaving accelerates hair growth?"
] | [
false
] | This belief seems to be quite prevalent. I've even had MDs tell me this. And I've heard the reason why women with wispy mustaches don't shave is because they're afraid it'll start growing even faster and darker. It would probably be quite easy to test scientifically, even for an average redditor. For example, shave one... | [
"The reason that this belief is held onto is likely because, in a sense, it ",
" true that shaving will make the hair grow back thicker than if you pluck or otherwise pull it out, or even leave it alone, because you're only chopping it off mid growth so that the thick part of the hair pops up instantly, and now w... | [
"AFAIR it is an urban myth, classic confusion of cause and effect. I'm sure this has been tested (after all hair growth is a HUGE commercial buisness). Hair growth depends on testosterone levels and genetics primarily. "
] | [
"BMJ says shaving has no effect",
"* (scroll a bit down), and there's a nice ",
"WikiAnswers page",
" on why that is so.",
"*) They mention a study from as early as 1928. I found one by a certain M. Trotter, but it is not available online. Take ",
"this one",
" instead."
] |
[
"Why is turbulence less dangerous than it seems, and when should we actually be worried while on a flight?"
] | [
false
] | null | [
"When you hit a bump in the road at high speed, it feels far more impressive than it actually was. It's similar with turbulence. Just like a sudden pothole, you probably don't anticipate it, it may cause discomfort, but it's not actually harmful as long as you're strapped in.",
"What's refered to as turbulence wh... | [
"Turbulence usually isn't a problem because modern aircraft are equipped with control systems that stabilize it during flight. Most turbulence only occurs for a brief period of time before the airstream returns to a fairly laminar flow or is compensated for by the flight controls.",
"Turbulence becomes a dangerou... | [
"Yeah I would imagine T/L turb is deadly. I always feel the least comfortable about 100-200 meters in the air when the aircraft performs its first 20 degree bank."
] |
[
"At what point does attraction to youthfulness become counterproductive?"
] | [
false
] | [deleted] | [
"Interestingly, male chimps prefer to mate with older females, presumably because the older females have shown they can survive long term and have lots of experience raising offspring. So the human approach isn't the default.",
"Oh, and about blonds. I can't guarantee it's the case here, but there's a phenomeno... | [
"hmm, on a side-track, why are certain people sexually attracted to prepubescent child given that this confers no reproductive advantage ?"
] | [
"hmm, on a side-track, why are certain people sexually attracted to prepubescent child given that this confers no reproductive advantage ?"
] |
[
"Multi-part Question: Fans vs Air Conditioner. Relative Humidity and Self Cooling. Overall Cost/Benefit."
] | [
false
] | It's that time of year, and the housemates and I are having "disagreements" about cooling and humidity. help us settle the argument. Fans & AC list Does it take more energy to run JUST the AC or 5 fans? What about with [2] more 8" single fans? The argument often shifts between the cost of the AC, but then the "it's to... | [
"I'd guess your A/C unit uses as much electricity as 12 box fans. 11,500 BTU A/C unit uses about 1200 Watts. A box fan uses around 100 watts. But thats only the amount of electricity it uses when the compressor is running. The exact amount of energy used by your A/C unit will depend heavily on what temp you set ... | [
"It's an older AC, early/mid 90s. The dial goes only to 10. It is set at a low cooling instead of high cooling. It is supplemented with fans. ",
"The flat doesn't stay cool long due to it being in the SW Corner of one of the higher floors. It does get a nice breeze when the windows are open. "
] | [
"Well then I would ",
"get one of these",
" and run an experiment to settle the debate. I'm pretty sure you'll find that not using the A/C will be the cheaper solution but A/C the quality of life that A/C can bring you is often worth the expense. "
] |
[
"If I lit a candle in space on a spaceship then what would the flame shape look like since there is no gravity?"
] | [
false
] | null | [
"Round"
] | [
"Here's the picture (it's a bit far down)"
] | [
"The reason that flames are ",
"tear-drop shaped",
" is because heated air is lighter density and rises, while convection draws cooler air into the flame, feeding it with oxygen.",
"In space, there is no \"up\", so the flame maintains a spherical shape. Incidentally, without the convection necessary to draw m... |
[
"How do machines produce randomly generated numbers from a distribution?"
] | [
false
] | I was lamenting about how much I had to mark this weekend, and jokingly proclaimed I should produce random grades according to a distribution. But how do machines do that? Suppose I wanted to generate a series of numbers that were distributed exponentially, or normally. What is the process for creating such an algorit... | [
"As long as you can produce random numbers from a uniform distribution you can transform them to whichever distribution you want by using the cumulative probability distribution of the desired distribution. ",
"https://en.wikipedia.org/wiki/Inverse_transform_sampling"
] | [
"That is really neat. Thanks for the post."
] | [
"This would be hardware technique. While an algorithm of some sort would be needed to turn this randomness source into something useful, the randomness itself does not come from the algorithm. No purely algorithmic (i.e. deterministic) process can produce true randomness."
] |
[
"Can anyone r/AskScience identify the strange creature currently residing in my bathroom sink?"
] | [
false
] | and of the beast in question. Saw it on my shirt in the mirror when I entered the washroom. I think it must have fallen on me while I was outside. Relevant information: Edit: I just noted the grammar fail in the title. My bad... | [
"In the future, if you have any insect ID questions, definitely check out ",
"/r/whatsthisbug",
". "
] | [
"It's an 'inch worm'- the caterpillar phase of the ",
"geometer moth."
] | [
"Yep. \"Inch worm\" caterpillar. They are abundant in the midwest of the US. I guess in Canada too. "
] |
[
"Why do photons impinging on a CCD camera exhibit poisson noise?"
] | [
false
] | I've never gotten a straight answer to this question. I know that this is true, but I don't understand why it is so. | [
"not every kind of light exhibits poissonian statistics and so it really depends upon what generated the light and how you are detecting it. ",
"There is also a big distinction between saying the light has poisson noise and the current coming out of the detector has poisson noise. ",
"So if you take the clean... | [
"I'm not really sure if poisson noise was an issue in film-based images or not. it depends upon what you were doing with it I guess.",
"\nBut yes, for a constant light source the moment you 'convert' to discrete things, that's when you get poisson noise. ",
"(however when you start moving away from a small mea... | [
"With film, the poisson effect shows up as ",
"grain",
"."
] |
[
"What would happen if I shot a photon orthogonally from a black hole?"
] | [
false
] | As in orthogonal to the event horizon. would it have to stop and turn around? Thanks | [
"A photon always travels in a straight line, but space itself may be curved such that this straight line doesn't look straight to someone somewhere else.",
"In a black hole (within the event horizon, and to the extent that it even makes sense to say this), space is so warped that there are no paths out of the bla... | [
"From the inside of the black hole or from the surface of the event horizon?\nIf from the surface, it would escape to infinity with \"infinite red shift\" - it's energy would be zero in infinity.",
"Behind the event horizon, the only permissible movement is towards the centre. No matter how you shoot it will fall... | [
"So the space its warped in a way that erik make it end up in the middle. That's crazy..."
] |
[
"How much energy could you produce by solar panneling the entire sahara desert?"
] | [
false
] | output with the technology we have now, and with near distant technology? | [
"2.8 quadrillion watts",
" with current technology. ",
"4.3 quadrillion watts",
" with the theoretical maximum of current technology.",
"Impurity band semiconductors could possibly get higher, as much as ",
"9.8 quadrillion watts",
".",
"Of course this is completely ignoring the difficulty of getting ... | [
"its just hypothetical, not practical at all, i know. "
] | [
"To put that in perspective, world energy consumption is about ",
"142 quadrillion-Wh",
", so we need about 50 hours of sunshine."
] |
[
"Are there any animals that eat mushrooms or plants that are psychedelic?"
] | [
false
] | null | [
"Reindeer are known ",
"to eat fly agaric",
". The author of Shroom claims that the stories about ",
"humans consuming reindeer urine",
" after the animals have eaten the mushrooms to get high are true."
] | [
"I've heard the opposite to be true: Reindeer would actually crowd around snow that humans have urinated in after consuming psychedelics, jostling each other to get a piece of the action"
] | [
"Plants are not inherently psychedelic, but rather psychedelic to humans (because of how they interact with our species' specific brain chemistry).",
"However, monkeys, elephants and cats (just off the top of my head) have been observed to imbibe alcohol or substances that are psychoactive to them for apparently ... |
[
"What's the maximum height a fly or a mosquito can reach?"
] | [
false
] | I mean flying of course! Is there a limit? How high is that? Why? | [
"National Geographic Article about bumble bees",
"\nI mention bumble bees because they were studied a lot by scientists. Some people thought bumble bees shouldn't be able to fly because they are too heavy, so they ran a lot of tests on them!",
"Helicopters have an upper limit of height in which they can safely ... | [
"I think it's quite obvious that there isn't really much science going into how high insects can fly, so there is no direct answer to the highest flying insect. The only insect that was tested was bumble bees, and they were found to be able to fly higher than the highest land on Earth. So the answer that is known i... | [
"Found a link that goes into detail",
"https://www.livescience.com/55454-how-high-can-insects-fly.html",
"The highest altitude where insects (butterflies and flies) have been found is 6000m. However, they tested bumblebees in a pressure chamber and they were able to fly at 9000m! (for reference, Everest is at... |
[
"Where do fish in high altitude/mountain streams and ponds come from?"
] | [
false
] | I've been hiking in Europe and Asia and have seen fish even in tiny puddles at very high altitudes, close to the ice cap source of the river. How the hell do they get here? Surely both migration and reproduction is incredibly difficult against a current and in such isolated bodies of water | [
"You always hear about birds transporting eggs, but I've never seen documented evidence of this (please, if anyone has a paper on this send it my way!). I have seen it documented for plants and aquatic invertebrates, however.",
"What ",
" definitely happen is that humans will introduce fish into every body of ... | [
"Dont forget that fish are very resourceful, and that seeing a puddle at one moment in time does not give you a complete picture of how it is related to other bodies of water. Water systems can be connected at different times and fish can migrate up them, then they become isolated stranding the fish in funny places... | [
"It's so interesting that you posted this here OP, I came to ask the same question almost exactly -- if X and Y lakes were frozen 10,000 years ago or not carved by the glaciers or formed by the melt water yet, then how could there possibly be fish in them? It's not like they could \"evolve\" there in 10,000 years, ... |
[
"How are quantum tunneling in stars and their weight associated with each other?"
] | [
false
] | null | [
"So is my answer widely false or just inaccurate?",
"It's inaccurate to imply that tunneling is ",
" crucial for the sun to sustain fusion at its current temperature and density.",
"If you take the core temperature of the sun and convert it to an energy (kT, on the order of the average kinetic energy of the p... | [
"It's inaccurate to imply that tunneling is not crucial for the sun to sustain fusion at its current temperature and density.\nIf you take the core temperature of the sun and convert it to an energy (kT, on the order of the average kinetic energy of the particles in the sun), it's on the order of keV. The Coulomb b... | [
"The fusion cross section would certainly be higher if the average relative energy were above the Coulomb barrier. I don't know what astrophysical implications that would have."
] |
[
"Is there any documentation of how much or what type of bacteria there are on the surface of the eyes?"
] | [
false
] | They say the mouth is where most of the bacteria are on your body, so I wondered how the bacteria on your eyes would compare. I am talking about the actual wet eye surface. Also in case anyone knows, if this bacteria is somehow destroyed for an extended period of time, will the eyes be harmed? | [
"I found one scholarly article:\n",
"http://www.ncbi.nlm.nih.gov/pubmed/19620859",
"\nDoes it help? Its probably not exactly what you're looking for.."
] | [
"your eyes are protected with enzymes, one of these is lysozyme which can disturb the reproduction of gram-positive bacteria but the article posted by thermalphysics seems to be a good point to start."
] | [
"Not exactly but that does help, thank you."
] |
[
"What is the correlation between brain size and intelligence? Is it possible for a large-brained animal to be unintelligent or a small-brained animal to be highly intelligent?"
] | [
false
] | null | [
"Sure. Rats have tiny brains, but they're quite intelligent. The ratio of brain size to body size matters a bit more than just overall brain size, but there's still not much of a proven correlation. There are just too many factors. ",
"It's probably down to evolutionary pressures in the end. Rats benefit from bei... | [
"Another thing to note is that birds have higher neural density than mammals, hence they can pack the same number of neurons in their smaller brains as a bigger mammalian one. Macaws for example are considered highly intelligent animals, some compare them to a 2/3y old human in that regard"
] | [
"To add on- there’s also the correlation of “how much energy is available” for brain power. Humans divert a proportionally huge amount of energy to our brains, whereas other animals do less so. Even so, among the animal kingdom there are varying levels of energy availability"
] |
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