title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why do the lights in this photograph each have 14 \"spikes\"?"
] | [
false
] | In , the bright sources of light each have 14 "spikes" surrounding them. I'm familiar with in astrological photography, which makes stars appear to have spikes, but that's caused by the struts holding the lenses in a telescope. An ordinary camera doesn't have struts like that—as far as I know—so what causes the spikes... | [
"It's actually due to a similar effect, except in the case of a camera like the one this photo was taken with it, it's due to diffraction of light around the edges of the the ",
"aperture's",
" ",
"diaphragm",
" blades.",
"The aperture is the hole through which light is allowed into the camera. Its functi... | [
"This is a good answer, except for one detail. Every \"vertex\" in the aperture shape actually causes a symmetric diffraction pattern with two spikes pointing in opposite directions. Thus, an ",
"-blade diaphraghm actually causes 2",
" spikes. When ",
" is even, though, each spike overlaps with another, makin... | [
"Oh, neat! Thanks!"
] |
[
"Do insects sleep?"
] | [
false
] | null | [
"Hi, this isn't for medical advice! I just want to know if insects sleep :/"
] | [
"Hi, this isn't for medical advice! I just want to know if insects sleep :/"
] | [
"LOL, I clicked the wrong button using my script. I'll click the correct button on the script and delete that, I'm sorry."
] |
[
"Do any forms of photography capture more wavelengths of light than we can perceive?"
] | [
false
] | For example, could you ever tell the temperature at which a photo was taken because the chemicals reacted to infrared? Or to radio waves? Edit: Sorry my question wasn't totally clear. I know it's possible to observe other forms of light through specialized photography, but I was thinking of a CSI type scene where on... | [
"This may not be quite what you're asking, but here is some relevant information:",
"There are films sensitve to the infrared, and ordinary films are sensitve to the ultraviolet, as discussed ",
"here",
". Though I believe it's no longer produced, ",
"Kodak Professional High-Speed Infrared Film (PDF)",
"... | [
"Yes, infrared photography that can detect temperature exists, though its usually digital. I'm sure chemical could be done, the real tricky part is in the lens given that infrared, well far infrared, doesn't go through glass. ",
"Neat trick, the infra red LED on your TV remote can be seen by cheaper, or night vis... | [
"The general term for that is ",
"hyperspectral imaging",
"."
] |
[
"Can you measure the same photon more than once?"
] | [
false
] | null | [
"Every photon is fundamentally identical to every other, so to say that \"a new photon is produced\" instead of the original doesn't really have meaning.",
"But the difference between Compton scattering and the photoelectric effect is that the photon is destroyed in the photoelectric effect, while there is still ... | [
"Every photon is fundamentally identical to every other, so to say that \"a new photon is produced\" instead of the original doesn't really have meaning.",
"But the difference between Compton scattering and the photoelectric effect is that the photon is destroyed in the photoelectric effect, while there is still ... | [
"Yes, as long as the first measurement doesn't destroy the photon."
] |
[
"Does wearing black clothes make a big difference in terms of heat perceived as opposed to wearing white clothes in a hot country?"
] | [
false
] | My really basic understanding of this field of physics tells me that white reflects the light spectrum while black absorbs it so my naive assumption would be that wearing white clothes should help tolerate hot weather better. But how big is the difference in actual heat that wearing white clothes helps reflect? Hope my... | [
"This has been studied a few times. It seems that the color has two effects that cancel each other out for the most part. Black absorbs heat from the sun, but it also wicks heat away from your body. White reflects the sun, but also reflects your body heat back in. ",
"https://www.wired.com/story/should-you-wea... | [
"So if you had a shirt that was black on the inside and white on the outside would that be even cooler ?"
] | [
"A bit of napkin math supports the everyday perceived heat difference between wearing light and dark colors on a sunny day.",
"Solar irradiance at sea level",
" amounts to about 1000 W/m",
". An adult human's ",
"body surface area",
" is about 2m",
", and assuming a ",
"spherical human",
", or more ... |
[
"Do we have an idea of how animals with more different cones in their eyes perceive the world?"
] | [
false
] | I understand that dogs have only 2 types of cones resulting in what we would perceive as color blindness, but do we have the capability to understand how a butterfly (5 color cones) or a mantis shrimp (16 color cones) sees the world? | [
"And Radiolab is wrong. Do centipedes or millipedes walk better or run faster because they have many legs? Just because a certain animal has more photoreceptor types doesn't necessarily mean that it perceives more colors! Because photoreceptors don't create color on their own. The subsequent processing in the brain... | [
"And Radiolab is wrong. Do centipedes or millipedes walk better or run faster because they have many legs? Just because a certain animal has more photoreceptor types doesn't necessarily mean that it perceives more colors! Because photoreceptors don't create color on their own. The subsequent processing in the brain... | [
"Our brains perceive color by comparing the output of all three cone types with each other and evaluating the ratios, in an ",
"antagonistic manner",
". With an increasing number of photoreceptor types, this system of weighing each receptor type against all others would take exponentially growing processing pow... |
[
"If one drops a feather and a bowling ball in a vaccum, shouldn't the bowling ball hit the ground first?"
] | [
false
] | After all, the bowling ball is pulling the earth to itself faster than the feather is. (I know that the difference will probably be beyond measurement error, but still) | [
"Ok, I'll go on record saying that if the Earth still had a radius ~ 6.37x10",
" but had a mass of only a 6000kg (instead of 6x10",
" there would be a measurable difference. ",
"To go through the calculation with M_earth = 6000kg, and m_ball = 1kg and m_heavier_ball = 100kg, we'd find that the force due to g... | [
"No. Physics is not math. In any problem you make tons of physical assumptions. If you find a difference that is orders of magnitude different than the realm of potential measurement there is no physical difference.",
"If the earth weighed say 1000kg (and had the same radius, non-deformable and nothing else is... | [
"As shown by Astronaut Dave Scott, No.\n",
"http://nssdc.gsfc.nasa.gov/planetary/image/featherdrop_sound.mov"
] |
[
"Why are atoms mostly empty on the inside?"
] | [
false
] | As far as I know, atoms are on the inside mostly empty and there's a lot of 'space' between the protons (& neutrons) and the electrons 'going around' the nucleus ('a lot of space' when comparing it to the size of protons and neutrons) My question is why don't electrons, with a negative charge, actually come even closer... | [
"The answer ultimately comes down to 'reality doesn't work like that'. On atomic scales, things don't behave as particles like you'd think, but instead of quantum objects. The behaviour of quantum objects is incredibly unintuitive, they are simply unlike anything you can see in normal life.",
"One of the strange ... | [
"Atoms ",
" mostly empty on the 'inside'. There's no 'inside' to speak of - there's a smooth distribution of electron density from the nucleus outwards. (we can only speak of the density, because in quantum mechanics, electrons in atoms do not have definite point locations) ",
"Electrons do scatter off the nucl... | [
"Electrons do not actually orbit the nucleus in the classical sense. They exists in very distinct bands around the nucleus called orbitals. Similar to (but not exactly like) classical orbit systems, atomic electrons have an angular momentum which keeps the electron at a distance. But it is quantized angular mome... |
[
"If the solar system existed the way it does now for eternity, how long would it take for all eight planets to simultaneously transit the sun from Pluto?"
] | [
false
] | If our solar system existed the way it does now, how long would it take for all eight planets to simultaneously transit the sun from Pluto? Like, if the sun never ran out of hydrogen fusion, and the planets all stayed in the exact same orbits they're in now. If ever, what unbelievably large period of time would take pl... | [
"The would require the alignment of all the planets, which happens approximately every 340 million years. Since this period is longer than the Lyapunov time of the solar system, we actually can't answer that question scientifically. ",
"*",
"- reference here -"
] | [
"It would be wildly inaccurate past 4 million years. The solar system doesn't run with the exactitude of a computer; orbits suffer small perturbations over time that we can't account for on long timescales. Small things we can't see, for example: minor asteroids, changes in local gravity fields (caused by extrasol... | [
"I don't think it would ever happen. Neptune and Pluto are locked into a resonant 3:2 orbit with each other. For every 3 orbits of Neptune, Pluto orbits twice. During those 2 orbits of Pluto (496 years), Neptune crosses between it and the sun once. However, due to Plutos orbit having a high inclination (17",
" ),... |
[
"If you added enough black holes to the universe to account for all of the dark matter. How many more black holes would there be compared to how many we think are there now?"
] | [
false
] | null | [
"Well, let's do the math. The dark matter accounts for about 23% of the density in the observable Universe. The total density is given more or less by the ",
"critical density",
", 3H",
" / 8 pi G, so we can calculate the dark matter density as about ",
"2.24 x 10",
" grams per cubic centimeter",
". Alr... | [
"The current values for what the universe is made up of with the dark matter model are ~4% Baryons (\"normal\" matter) ~23% Dark Matter and ~73% Dark energy. That means that if black holes were to account for all this dark matter there would be about 6 times the observable mass of the universe as black holes. Also ... | [
"2.24 grams per cubic centimeter",
"2.24 x 10",
" g/cm",
"?"
] |
[
"If the sky is blue because blue light gets scattered more in the atmosphere, why it is said that the sunset is orange because all the blue light got scattered and is missing? Shouldn't the sky look even more blue then?"
] | [
false
] | null | [
"One way to think of it is that the light emitted by the sun is white - a combination of all colors ranging from blue to red (simplistically). If blue gets scattered then what remains is more red (again simplistically). Once the sun gets to a low level - so much blue is being scattered that what light remains looks... | [
"A small addition: the scattered light does not strictly remain in the atmosphere, it scatters randomly. As such, some amount of it is lost to space, and the further the light must travel, the more that is scattered into space.",
"I imagine there are some other losses, such as conversion to infrared over distance... | [
"Light doesn't scatter randomly. There are well defined, non random, scattering cross sections. But your point still remains that there is a change in the forward intensity of the light, for example, due to the angular cross section of the scattering event."
] |
[
"IUPAC name of adamantane"
] | [
false
] | hi, can anybody explain me how the IUPAC name für adamantane is formed? According to Wikipedia it's: Tricyclo[3.3.1.1 ]decane What do the numbers in the brackets mean? I'm am familiar with the concept with two compounds like Bicyclo[2.2.1]hexane, but I do not quite comprehend how to do it if I have 3 rings or more. es... | [
"Start with Bicyclo[3.3.1]nonane and add a one-carbon bridge across C3 and C7, and you get Tricyclo[3.3.1.1",
" ]decane"
] | [
"Tricyclo compounds are slightly different than bicyclos. Looking at ",
"this",
" you can see that the longest cycle you can form is 8 carbons (in red) with two bridges (1-5 and 3-7). First you want to make one bridge your major bridge. The longer bride will be the major but since they're both one carbon bridg... | [
"thank you, that was very helpful :D"
] |
[
"What's the mechanism that repairs DNA mutations? How similar is it from one lifeform from another?"
] | [
false
] | The question in the title, mainly. I know a bit about microbiology but we still haven't touched that subject, so I want to know what mechanism repairs DNA 'mistakes' when the cell is about to divide, and if it's pretty much the same from one species to the other, or if on the contrary the one we have and the one a chim... | [
"There are actually a ",
" of proteins involved in DNA repair!",
"The first line of defense against mutations is the protein that actually makes the copy strand of the DNA during replication, call a DNA polymerase. In humans, our polymerase has a high fidelity, meaning it makes mistakes relatively rarely--but o... | [
"Keep in mind there are different types of DNA repair for different types of DNA damage. \nThere are 4 major types of DNA repair\n",
"mis-match",
" repair fixes base/base mis-matches that occur during DNA synthesis by clipping out the mismatched base of the new strand (the old strand is methylated which is how ... | [
"Not all replications are caught - which is why you see trait differences between people. There are mechanisms to catch most DNA errors - due to the fact that some errors can be lethal to the cell / organism (embryo dies during development, cancer forms in a full human). DNA polymerases are the most common error ... |
[
"Why does COVID-19 affect people differently?"
] | [
false
] | This may have been asked here before, but I’m trying to understand how a virus can show completely different symptoms in one person versus the next. For example, Donovan Mitchell, a NBA shooting guard for the Utah Jazz, tested positive for COVID-19 a week and a half ago. He’s repeatedly stated that he is completely asy... | [
"Physician here. The answer is the genetics and experience of your immune system. In layman’s terms there are two important decisions your body must make. The first is how aggressively does the body want to fight the virus when it initially enters your body. Usually this is at the level of your throat before it ge... | [
"Thank you, great answer."
] | [
"Just to correct one other misconception you have, lots of times the flu is asymptomatic. Up to half of seasonal flu cases can be asymptomatic, you just didn’t know about it because you only notice the symptomatic cases."
] |
[
"Why do we not cough in sleep?"
] | [
false
] | Hello! First post here so bear with me. So, ever since I recovered from covid in May 2021, I've had this long covid wheezing and coughing it's not extreme just a little bit don't worry, anyway I was thinking, I just woke up from a night's sleep and I was coughing last night and now this morning. Why do we not cough in ... | [
"Since body movement, or rather nerve transmission down the spinal cord, is inhibited during sleep, you can't cough or sneeze. Your body does, however, enter a wakeful state very briefly to cough/sneeze but you won't remember it happening."
] | [
"If you ever got taught to turn a drunk person on their side when they're passed out, this is why. The sympathetic and parasympathetic nervous systems work weirdly. You'll wake up just enough to coiugh, sneeze, vomit, fart, sit up right (oh yeah that's a medical consition), sleep walk, piss yourself etc. but you ... | [
"Oh I see, that makes a lot of sense. Thank you :)"
] |
[
"Has the concept of living in harmony with nature really been a substantial part of native people's culture or did they just lack the economy and technology of exploiting nature in a fashion similar to that of the 'white man'?"
] | [
false
] | The notion that native people (especially in Australia and America) tried to preserve and live in some kind of harmony with nature sometimes occurs in documentaries. I was wondering if it has any merit. Why would they have stopped expanding their hunting activities, for instance, had they had the means? Why wouldn't th... | [
"One of the central tenets of ",
"Guns, Germs & Steel",
" is that European and Asian societies advanced beyond 'native' societies in terms of technology because they had the opportunity (necessity, even) to do so. ",
"Once some sort of technology enables a population to out-compete its neighbors, it does. "... | [
"Living in balance with nature, what does that even mean?",
"What would it look like for a primitive people to live out of balance with nature? They would have too many children and eat too much food...and then they would die until the balance was restored.",
"These people don't choose to live in balance with ... | [
"Less than you might think. Religion being antithetical to science is a relatively recent phenomenon. Certainly there were ",
"some instances",
" that were specific to the time and culture, but organized religion has ",
"done well",
" by science in the past. Some natural sciences have ",
"their roots",... |
[
"Do nuclear weapons lose potency/power over time as their radioisotopes decay?"
] | [
false
] | We have been going over radioactvity a lot in science class lately and how radioisotopes decay through a half life system. I was wondering if the half life of the radioactive material in nuclear missiles/bombs lasts long enough to never be replaced until use or if it needs to be constantly refreshed. | [
"Yes, however there is a lot to be considered.",
"First is the fission based element will not have a significant reduction. U-235's half life is 700 million years, and Pu-239's half life is 24100 years. So for our time span, either element would not have a substantial reduction in fissionable density.",
"Now th... | [
"Thank you, that was a very thourough explanation."
] | [
"Uranium and plutonium have such a long half-life that nobody worries about them losing strength, but the triggers for them have a much shorter half-life and have to be replaced periodically. "
] |
[
"Are there cultures where smiling is not used to show happiness? If not, how did it develop to mean this across the world?"
] | [
false
] | null | [
"Like birds know to fly south in the winter, humans are born with certain facial expressions as a representation of emotion. Facial expressions associated with disgust, happiness, surprise, fear, anger, and sadness have been found to be the same across the world, including cultures isolated from the rest of the wo... | [
"relevant, ",
"http://en.wikipedia.org/wiki/Paul_Ekman#Emotion_classification",
"Ekman devised a list of basic emotions from cross-cultural research on the Fore tribesmen of Papua New Guinea. He observed that members of an isolated culture could reliably identify the expressions of emotion in photographs of peo... | [
"I thought the most interesting part about this from my Psych 101 class was that, even blind people know the facial expressions."
] |
[
"Can animals smell water?"
] | [
false
] | null | [
"Did you downvote what I said then copy it?"
] | [
"Did you downvote what I said then copy it?"
] | [
"This is a strange question. Animals can perceive humidity in various ways. If you mean to say \"Can animals use smell to detect sources of water?\" then it is certain that many animals can perceive the smell of things associated with bodies of water. Humans can perceive both humidity and sources of water in the ri... |
[
"Why are Homo sapiens and Homo neanderthalensis considered separate species if they interbred and produced fertile offspring?"
] | [
false
] | null | [
"Anthropology student here. That's actually a really good question, and one that's debated in the Anthropology community still. One of my professors does not think that H. sapiens and neanderthalensis are different species at all. Instead, neanderthals are just a morphologically distinct subspecies of H. sapiens (H... | [
"As Circus2 suggests, it really depends on who you ask. However, I'll note that there is some evidence of infertility between humans and neanderthals. The amount of DNA crossover between humans and neanderthals is most consistent with a relatively small number of hybridizations (I've seen estimates as low as one ... | [
"Of course! Physical anthropology is definitely my focus, so this question was one I felt that I could answer. I do wish there was a more concrete answer, but it really is a point of contention in the anthropological community.",
"Thank you again for your kind words, they mean a lot to a lowly student such as mys... |
[
"What is it about grapefruit that has some medicines say \"Do not eat grapefruit or drink grapefruit juice while on this medicine\"?"
] | [
false
] | I was recently given some samples of Seroquel XR by my doctor, and it has a grapefruit warning on it. My dad takes several medicines for his heart and I believe several of them have the "no grapefruit" warning on them too. What is it about grapefruit that isn't in other citruses? | [
"This is a great question and a very important one. Grapefruit juice (and some other fruit juices, but to a much lower extent) contain molecules, such as bergamottin, dihydroxybergamottin, and paradicin-A, which inhibit the metabolism of drugs that are metabolized by a specific liver enzyme (CYP3A4). Drug dosages a... | [
"In theory yes, but grapefruit juice isn't standardized so results would vary between brands and batches of grapefruit juice. Some medications have a very narrow therapeutic index (ratio of lethal dose to effective dose) so you don't want to risk overdosing because it could be fatal or produce side effects such as ... | [
"Couldn't you then, in theory, take a smaller dosage of a drug and supplement it with grapefruit without sacrificing its efficacy?"
] |
[
"Is there a smallest-possible temperature difference?"
] | [
false
] | Given that temperature is defined thermodynamically via molecular vibration, is there a smallest-possible difference in the degree of this vibration and therefore a smallest-possible temperature difference? I suppose temperature is typically given as an average within some medium, and so the above consideration might n... | [
"Actually, temperature is defined as the ",
"derivative of internal energy of a system with respect to its entropy, under constant volume and number of particles",
". Certain particle velocities just correspond to certain temperatures.",
"This is why you shouldn't only consider vibrations when thinking about ... | [
"(assuming temperature is defined as the average kinetic energy of the system)",
"But it isn't defined like that. It is defined as the derivative of the internal energy with respect to its entropy. For many systems, this happens to correspond to the average energy per degree of freedom, but that is not the defini... | [
"Although it is unlikely that this value is the smallest possible difference, it does represent the current record holder for closest approach to Absolute Zero. 100 picokelvins or .000 000 000 1.",
"There is research that indicates measurement down to femtokelvin values is possible.",
"For my purposes, I think ... |
[
"What human actions actually increase the universes net entropy?"
] | [
false
] | Basically what human actions or activity actually increases the net entropy of the universe beyond the natural rate from the sun and tidal forces of the solar system etc... The only thing I can think of that doesn't come back to energy from the sun or geology is refining nuclear fuel causing the decay to accelerate. An... | [
"Everything we do including breathing. There is no such thing as reducing entropy globally."
] | [
"You misread my post. Global is a colloquial word for \"universe\" in systems processing. Reducing the entropy of any sub system is possible as long as the ",
" i.e universal change is still positive.",
"Therefore all actions always increase entropy if you make sure to consider enough of the system. The volume ... | [
"It is actually possible to reduce the total entropy of a system (through random fluctuations). However entropy does still tend to increase so it's not really something that needs to be considered."
] |
[
"How high up in the atmosphere must one go before you could find no more life?"
] | [
false
] | null | [
"If by \"life\" you are referring to complexer lifeforms like birds, then the limit would be the stratosphere, or to be more precise, the tropopause, which marks it's border. At this hight the air gets very thin and the temperature drops from about 0°C to -50°C. This happens at a height of about 10-15km above seale... | [
"The ",
"Bar Headed Goose",
" is thought to be one of the highest flying birds. "
] | [
"Life has been found at 398 km above sea level. Of course, it took rockets to get it there..."
] |
[
"Given a sufficiently large rotational diameter, would the human body be able to tell the difference been simulated gravity on a space station and real gravity?"
] | [
false
] | It is my understanding that we can simulate gravity in a free-fall environment using large, rotating sections. Assuming the section was sufficiently large to prevent a noticeable force gradient, with the appropriate velocity to create Earth-like gravity, would there be any practical difference between this and real gra... | [
"No, simulated gravity from rotation, as long as the diameter is sufficiently large, would not be any different than acceleration due to gravity.",
"Obviously, if the diameter is small, then the force gradient could be significant, and the Coriolis effect comes into play at higher speeds, but with a big, slow don... | [
"If there was no detectable force gradient, then no. Gravity itself ",
" an effect of an accelerating reference frame, so there is fundamentally no difference."
] | [
"No, Einstein's Equivalence Principle states that gravitational force and the force experienced due to acceleration are essentially the same. Given the right specs on the rotation it would be indistinguishable from gravity we feel on Earth."
] |
[
"Why do I perceive sunlight as yellow?"
] | [
false
] | As we evolved, the sun was the only notable light we had (besides the occasional fire). Having grown with sunlight being the basic backdrop the eye evolved to see, why doesn't it see it as pure white light? | [
"Plants look green to us because that is the band of visible light that they utilize the least and reflect the most, while they are quite handy at absorbing far red and utilizing it. Even if we could perceive far red, plants would still look green. ",
"This might clear it up a bit."
] | [
"Upvote to jackcox. The atmosphere Rayleigh scatters blue strongest, so blue is scattered out of the path between you and the sun, removing some blue frequencies while distributing them over the rest of the sky. \nRed is scattered strongly by submicron size dust in the atmosphere, making the sunrise and sunset red... | [
"The sun actually has peak output in of 500 nm, which is green light, not yellow."
] |
[
"Are humans the only species of animal that continue to drink milk past the maternal bond with the mother? and if so, why is this?"
] | [
false
] | null | [
"In our evolutionary history the default was that humans, like all other mammals, would not be able to process milk (or in our case, milk products as well) into adulthood. \"Since lactase's only function is the digestion of lactose in milk, in most mammals species the activity of the enzyme is dramatically reduced... | [
"You could have a few European genes floating around in you somewhere, or you could have the lactose-tolerant trait independently generated. I'm pretty sure the mutation (or multiple mutations with the same net result) has happened several times. So enjoy your ice cream. You deserve it!"
] | [
"You could have a few European genes floating around in you somewhere, or you could have the lactose-tolerant trait independently generated. I'm pretty sure the mutation (or multiple mutations with the same net result) has happened several times. So enjoy your ice cream. You deserve it!"
] |
[
"Why are some animals so intrigued with laser pointers?"
] | [
false
] | null | [
"Would laser dots (or maybe other light sources) look differently to (some) animals than it does to us?",
"\nIs there a case where certain lasers or lights would just appear as this distracting/pulsating/unnatural object to pets or wildlife?"
] | [
"Dogs (and some cats) instinctively chase these bright-red dots simply because the dots move. Movement automatically stimulates their innate prey drive, which explains why lower-on-the-food-chain animals such as rodents and rabbits often freeze in place as a survival strategy. Although dogs aren't so discerning whe... | [
"This video shows how various African Cats react to a laser pointer:",
"https://www.youtube.com/watch?v=EOY1LVjohrw",
"How they react to it seems to correlate with the size of the animal. The animals seem to think that the laser pointer is a bug. A smaller animal that would hunt insects or other small prey ch... |
[
"How do animals know that they should perform certain behaviours, even if never shown by their parents/peers?"
] | [
false
] | For example, my rabbit was kept in a hutch from birth separated from the mother. And as soon as I took her home and allowed her to run in my backyard under supervision, the very first thing she did was start digging a burrow. How did she know to do that? She had never, ever been shown to do that by any other rabbit. | [
"All organisms have certain instincts or reactions built into their biology.",
"This is why, within reason, animals and plants will always exhibit characteristic behaviours when given the opportunity.",
"It's very literally in their genes. They simply learn faster and potentially more effective ways to use thos... | [
"To add to this, how exactly certain behaviors are encoded genetically is not known at this point. How genes result in certain traits, and how the brain operates, are two big questions in biology, and this is the intersection of those two, so pretty much a big unknown. We do know certain genes and gene variants tha... | [
"I watched one of Robert Sapolsky's lectures and he said that after exquisitely detailed experiments they managed to determine that chicks instinct to peck the ground and eat worms manifests at first as an urge to peck their own toes. Apparently after doing this for a while and pecking at something edible by mistak... |
[
"What’s the strongest possible earthquake that can happen on earth? Is there a theoretical limit?"
] | [
false
] | null | [
"There is no formal limit, but it is important to realize that the sizes (i.e. the ",
"magnitudes",
") of earthquakes generated by faults are directly linked to the area of a fault that ruptures during an earthquake, e.g. the scaling relationships in ",
"Wells & Coppersmith, 1994",
" or the ",
"variety of... | [
"Because the San Andreas and associated faults are strike-slip and thus are close to vertical in terms of their orientation, the maximum expected magnitude of an earthquake is less than what is possible on a subduction zone, like what is off the coast of Chile or in the Pacific Northwest of the US (because these su... | [
"Because the San Andreas and associated faults are strike-slip and thus are close to vertical in terms of their orientation, the maximum expected magnitude of an earthquake is less than what is possible on a subduction zone, like what is off the coast of Chile or in the Pacific Northwest of the US (because these su... |
[
"How do we know where the tectonic plates are?"
] | [
false
] | I get that we can tell where some are from fault shifts and whatnot, but I am sure that's not the case for all of them, especially ones at sea. | [
"Geophysicist here. Pretty much this.",
"There is a lot more supporting data now (gravimetric, seismic, volcanic geochemistry, etc.) but the original theory of plate tectonics was a unifying theory of planetwide observations of these three large scale geomorphs. "
] | [
"Layman here. I am pretty sure that ",
"mid-ocean ridges",
", ",
"oceanic trenches",
" and ",
"tranform faults",
" are pretty visible as plates boundaries."
] | [
"Just to put an official stamp here here:",
"rockyTron, rocketsocks and probably_wrong_but all have the right answer. ",
"There are a few ways to define what a plate is. I think rocketsocks has the best explanation of how large scale plates are worked out, but rockyTron alludes to the fact that sometimes things... |
[
"Is there much agreement on the future (end) of the universe."
] | [
false
] | I was watching episode where brian cox describes the process of entropy increasing and the fate of the universe at the end of time. I have typed out some of his words below, Is his summary true correct and widely accepted?, it is just I seem to recall that people were not really sure about if the universe will end and... | [
"It is the most likely scenario. If the universe has sufficient matter it can collapse back in on itself (I don't know what is supposed to happen after collapse). As long as the universe continues to expand it will die of heat death."
] | [
"We know with a fair deal of confidence that the universe is flat in curvature. We know with a fair deal of confidence that General Relativity, and in specific the FLRW metric well describes the physics of the history and fate of the universe. We know with a fair deal of confidence the mass and energy densities wit... | [
"I found the episode very entertaining but found his certainty in this area a little troubling in that my instinct from reading various responses here and reading generally,is that it seems, we do not know certain facts for sure."
] |
[
"This New Scientist article says that research shows there is no difference between male and female brains. How true is that?"
] | [
false
] | I'm no scientist, I'm just fascinated by the human brain and do a lot of reading about it. I believe I've read before that there are structural differences in human brains based on gender. For example, that the corpus callosum is thicker in males. Men have more "grey matter" and women have more "white matter". Women ha... | [
"The ",
"original study",
" is attacking a straw man. Here is the key sentence in the abstract that shows this:",
"However, such a distinction would be possible only if sex/gender differences in brain features were highly dimorphic (i.e., little overlap between the forms of these features in males and females... | [
"There are absolutely differences; both structural and functional. A simple search of \"sex difference brain\" in google scholar comes up with ",
"this paper",
". There are plenty more. "
] | [
"In light of the high degree of similarity in male and female bodies, it might be tempting to dismiss the significance of a few highly sexually dimorphic, but relatively small, organs, which, not coincidentally, are very closely tied to reproduction. That is what happened in this study. Because we can't yet identif... |
[
"Where is our universe traveling?"
] | [
false
] | I understand that the Earth revolves around the sun. And so does the other 7 planets. But what about the sun? I don't recall it revolving around anything. Are we just hurtling through space in one particular direction. Where are we going. Are we going further into the Galaxy? What about the entire Galaxy as a whole? Wh... | [
"The Sun is orbiting around the centre of the Milky Way in a roughly circular orbit. The gravity for this comes from the billions of stars in the middle of the Milky Way, plus all the dark matter concentrated there. There's also a supermassive black hole in the centre, but that's only one object and while it's much... | [
"Yes, the black holes end up \"sinking\" to the centre of the new galaxy, and eventually getting close enough to merge. (Note that black holes \"sink\" while most stars just have happy circular orbits: this is just because black holes are massive enough that things like \"dynamical friction\" start to be important,... | [
"Well, very few stars will collide at all, just because there's so much space between them compared to their size. When stars collide, they're almost always stars that formed in the same system or cluster.",
"But in the rare case that a pair of stars with radically different orbits do collide, they almost certain... |
[
"Why does the moon and the sun appear larger when near the horizon? Are they actually closer or it is some form of lensing from the atmosphere or Earth's gravity?"
] | [
false
] | null | [
"It's an optical illusion. When it's near the horizon your brain is tricked into thinking it's bigger because you have objects on the horizon for reference. ",
"If you bend over backwards and look at it upside down (or bend over forward and look through your legs, doesn't matter), the apparent biggification of th... | [
"It's completely an optical illusion. You can use the ruler trick you mentioned to prove that the sun and moon are virtually always the same size in the sky, especially throughout one day and night cycle. When compared to mountains or buildings on the horizon, the moon looks a lot larger than it does when it is alo... | [
"The most common objects in the sky are clouds, and clouds certainly seem to obey the regular laws of perspective. Clouds overhead are much closer to you than clouds in the horizon, and consequently appear larger. Our intuitive model of the sky is a large but very shallow dome.",
"Now, this does not hold for the ... |
[
"What is it that \"keeps\" a photon together?"
] | [
false
] | I've heard photons described as just bundles of energy. If you can narrow a beam of light into individual photons, and there's no outside force acting on them to keep the energy from dispersing into some other form of energy, what keeps it inside its containing "cluster"? | [
"I suspect a simple error in language there. The individual to whom you're speaking said \"We don't know,\" when what was meant was \"I don't know.\"",
" common mistake."
] | [
"Gravity is curvature in spacetime. Electromagnetic waves are waves propogating through the electric and magnetic fields. Again, I don't know who's been telling you otherwise, but these are fairly well understood things."
] | [
"Photons are elementary particles just like electrons; they're just elementary particles that don't happen to have any mass. That's not the same thing as being just energy, and in fact there's no such thing as \"just energy\" floating around in space."
] |
[
"What is the smallest unit that we can see with any microscope? Is it possible to see a molecule with an electron microscope, for example?"
] | [
false
] | [deleted] | [
"With an atomic force microscope, I've imaged the sheet of carbon atoms on a bit of graphite. The image showed each carbon as a 'fuzzy ball shaped lump'. Individual atom resolution is possible. ",
"(Though I suppose I was actually imaging the deflection of the AFM tip due to the electron cloud around each carbon ... | [
"He isn't talking about an optical microscope (or how they're called). It's not a thing that works with lenses to magnify small things. So in that sense you can't really see them. You can see them in the way that a radar operator can see an aircraft. Because of the deflection the microscope is able to capture."
] | [
"Wait - you can actually see ",
" atoms?!"
] |
[
"Is it physically possible to build a laser gun/cannon?"
] | [
false
] | Like Star Wars blasters. I don't know anything about the composition or physical properties of lasers. Is it possible for them to move through the air like bullets? What sort of damage would they do? Otherwise, what would be the closest thing to a laser cannon that we could theoretically build? | [
"We have things such as rail guns, however they take a lot of energy and are very, very large. ",
"There are also powerful laser cutters that industries uses to cut metal. However, again, take up a lot of power and are very big and bulky. They're not powerful enough to be mounted on ships or anything.",
"Handhe... | [
"Railguns don't have to be large if you aren't trying to accelerate large projectiles. I've seen tabletop ones shoot nails into cinder block.",
"http://web.mit.edu/mouser/www/railgun/halluc/intro.html",
" < old link I found with a quick google, but the basic electronics probably haven't changed."
] | [
"They wouldn't fly through the air like bullets; they would travel instantly as a light beam. Laser weapons are theoretically possible, but useful lasers are outside the reach of current energy storage systems, and atmospheric dust can have a huge impact on efficency at long range. Still, they have promise becaus... |
[
"i was watching cosmos and i wondered: is a neutron star kinda like a really big element?"
] | [
false
] | i'm thinking in terms of the bigger elements on the periodic table. we go out to Ununoctium 118 and i'm wondering if a neutron star is similar to a huge element with some big atomic number. *edit: if not, what are some of the big differences? thanks | [
"Neutron stars does contain protons, electrons and ions of \"whole\" elements in the crust. ",
"http://en.wikipedia.org/wiki/File:Neutron_star_cross_section.svg",
"What separates a neutron star from an atom is that it's bound by gravity rather than strong interaction."
] | [
"I would say that we don't know enough about neutron stars to say for sure how similar the core of a neutron star is to a very large atomic nucleus. I can say that the majority of the volume of a neutron star is a few orders of magnitude less dense than the nucleus of an atom, and basically consists of various atom... | [
"The difference between a neutron star and a nucleus is how the constituent particles are bound together. Think of a neutron star as a big sea of neutrons. While a nucleus in an atom consists of particles bound together by the strong force. A neutron star is not bound together by the strong force (which acts over v... |
[
"How does Hydrogen bonds 2 nucleobases (DNA) if it has only one electron ?"
] | [
false
] | How does it work? If it is bond with example, Guanine, how can it bond the same time with Cytosine? | [
"See ",
"hydrogen bond",
" - there is even an ",
"image",
" showing a GC pair. It is a type of intermolecular interaction (i.e., not a covalent bond) that describes the attraction between a bonded hydrogen with another electronegative atom. The interaction is basically electrostatic - that is, since the hyd... | [
"All chemical bonds are \"physical\" bonds. They are ",
" based on electromagnetism. The difference between them is just how tight they are. In that way, hydrogen bonds aren't in some form of special category.",
"Hydrogen bonds are, as you probably know, weaker than covalent bonds, but stronger than van der Waa... | [
"All chemical bonds are \"physical\" bonds. They are ",
" based on electromagnetism. The difference between them is just how tight they are. In that way, hydrogen bonds aren't in some form of special category.",
"Hydrogen bonds are, as you probably know, weaker than covalent bonds, but stronger than van der Waa... |
[
"What species is this?"
] | [
false
] | These pictures are from somebody else, but my friend and I found something very similar at a lake in British Columbia on the weekend. There were several crawling along an underwater log, within a metre of the surface. Any information on the species and how they construct their wooden "shell" would be really helpful. ... | [
"A bagworm moth ",
"http://en.wikipedia.org/wiki/Bagworm_moth",
"\nPossibly from the Genus Oiketicinae ",
"http://bugguide.net/node/view/43842"
] | [
"Cannot upvote this enough, because I was going to say the same thing."
] | [
"There comes a point in a person's life where they realized they've seen Jurassic Park too many times. This is then subsequently followed by another realization that it is impossible to see Jurassic Park too many times."
] |
[
"Given what we know about the life cycle of stars and heavy element formation, what is the earliest life as we know it could have formed in the universe?"
] | [
false
] | null | [
"It isn't just the existence of the elements but how prevailant they would be in the accretion disk. A single supernova could release as much iron as exists in the Earth, yet unless that iron finds its way diffuse enough to recombine into a terrestrial planet then \"life as we know it\" might be kind of hard. ",
... | [
"A hundred million years after the Big Bang is too early for life. The first stars didn't even begin forming until roughly 150 million years after the Big Bang, and these stars were almost certainly extremely massive, hot, and short-lived, meaning that their planetary systems would never even cool down enough for l... | [
"How fast do supernova dissipate into the ISM? I was trying to find ages for nebula and they seem to be on the order of millions of years. Say it takes tens of millions of years to get a good dispersion. Once that happens though the second generation will form and it will have some proportion of metals.",
"Thing ... |
[
"Can humans develop a tolerance for hormones and neurotransmitters?"
] | [
false
] | [deleted] | [
"Type II Diabetes can be a tolerance to insulin."
] | [
"Yes, this is called ",
"downregulation",
".",
"An example of downregulation is the cellular decrease in the number of receptors to a molecule, such as a hormone or neurotransmitter, which reduces the cell's sensitivity to the molecule. This phenomenon is an example of a locally acting negative feedback mecha... | [
"tolerance to hormones and transmitters produced by your own body doesn't happen physiologically because of the regular +ve and -ve feedbacks that keeps the levels of these hormones balanced according to the saturation of the target cells receptors in order to prevent these cells from tolerating the substances , so... |
[
"AskScience AMA Series: I'm Diego Pol, a paleontologist and Nat Geo Explorer. AMA about dinosaurs!"
] | [
false
] | Hi! I'm Diego Pol, a paleontologist and National Geographic Explorer who studies dinosaurs and ancient crocs. For the last few years, I've been exploring and discovering dinosaurs in Patagonia, the southern tip of South America. I'm the head of the science department at the Egidio Feruglio paleontology museum in Patago... | [
"You're already gonna have a bunch of clever questions, all I wanna know is what's YOUR favourite dinosaur?"
] | [
"Good one!",
"My favorite dinosaur is Carnotaurus!"
] | [
"I think the most surprising change is that we can now know the color of dinosaurs (of some at least).",
"But also that we can now use high resolution CT scans so we can access the inner part of the fossils, such as the brain cavity and reconstruct the shape of a dinosaur brain"
] |
[
"Why do cooked eggs warm up so fast in the microwave?"
] | [
false
] | When I warm up my kids eggs in the microwave, it takes maybe 4 seconds and they are hot and crackling. By 6 seconds they are popping/exploding. Is it trapped gasses in the eggs getting liberated? Water pockets? What is it about eggs that does this? | [
"This isn't all wrong. The popping is indeed steam escaping from the eggs. Eggs (not an expert on this part) are probably not an open mesh (like a sponge), so steam generated below the surface can't just drift out.",
"Another advantage of reheating eggs is that they are generally a thin layer. Water blocks microw... | [
"This is a good description thanks. ",
"I knew how microwaves work (vibrating water molecules), but NoJoDel's description would make you think that a glass of water boils almost instantly, which isn't the case at all. If I boil water in a cup for a tea, I have to put it in for 2-3 minutes, but my egg starts explo... | [
"This is outside my expertise, but I'd have to say yes. You heat the outside of the egg, water below the surface boils, can't exfiltrate, so has to burst out.",
"Ever microwaved a very wet sponge? (4 minutes on high to disinfect) No popping or anything."
] |
[
"If You Drop A Penny In A Bucket On A Scale, When Is The Penny Weighed?"
] | [
false
] | Let's say there's an incredibly accurate scale, with a bucket of completely still water sitting on top of it. If I were to drop a penny into the bucket of water, would the scale register the weight of the penny when it first hits the water, when it is sinking toward the bottom, or when it finally settles on the bottom ... | [
"Consider the balance of forces on the penny, and the resulting balance of forces on the bucket. Let's consider the simpler case of a sphere that weighs the same as a penny (so that the drag force is the same on the sphere no matter what its orientation).",
"1) The sphere is falling through the air at some initi... | [
"I think you are 99% of the way there, but here are two points of additional detail:",
"First, it needs to be clarified that the reading of the scale does not instantaneously jump from ",
" to ",
". The reading increase will be quick, but continuous. (While the penny is entering the water, there will be some ... | [
"There is downward force being exerted on the scale as soon as the object hits the water. And the full weight of the object would be felt either when it hits its terminal velocity in the water (and could drop no faster) or when it hits the bottom."
] |
[
"Would it be possible for cars to stop quicker, if when slamming on the brakes the tires went in reverse?"
] | [
false
] | null | [
"Then how do you stop if pushing the pedal makes the tires spin?"
] | [
"I understand that issue, but say it was a third pedal. In case an emergency you needed to stop faster than the brakes could, would this make you stop faster or just cause other issues. "
] | [
"Ok suppose you press this third pedal -- how do you know when to switch from this pedal to the brake pedal so that you don't start moving at speed at the car behind you? "
] |
[
"How is it possible to use nuclear power in outer space?"
] | [
false
] | null | [
"There is no need for atmosphere or oxygen to make a nuclear reactor work. About 20 nuclear reactors have already been used in space."
] | [
"Thanks, I will dig on that. Have a really nice day."
] | [
"A few links to get you started:",
"https://en.wikipedia.org/wiki/BES-5",
"https://en.wikipedia.org/wiki/Nuclear_power_in_space"
] |
[
"[Physics] How can photons have momentum P yet have no mass?"
] | [
false
] | null | [
"The specific question from that thread was \"Is light massless? Why is it affected by gravity? Why does light have momentum?\" and while the answer given pertained somewhat to mine, I do not think it was comprehensive. Furthermore, I would like to hear more answers to my question specifically. Although their can o... | [
"This is answered in the physics FAQ."
] | [
"The response given to the FAQ question \"does light have momentum?\" is correct, complete, and answers your question. Why do you think it is not comprehensive?"
] |
[
"Why do cavities and necrosis turn teeth/tissue black?"
] | [
false
] | [deleted] | [
"Depending on the cause of necrosis, necrotic tissue can be a variety of colors ranging from black to purple to yellowish or white. The type that most people are familiar with is avascular or ischemic necrosis (which turns black), where blood flow and/or oxygen delivery is interrupted. As cells in the region begi... | [
"The coagulated protein gunk is usually opaque and dark-colored, giving the dead tissue a black or purple appearance.",
"It's probably not the protein, ",
" but heme and products of heme degradation. Proteins, amino acids, and their degradation products are mostly colorless. Same for other biomolecules like lip... | [
"A lot of decay is black, but I also see decay that is tan, light brown and dark brown. Occasionally, I'll see green decay. It has to be because of the vast variety of bacteria involved and the multitudes of degradation products formed. I read that hydrogen sulfide produced from certain bacteria will react with iro... |
[
"Is there a way to physically visualize electric or magnetic flux in real-time?"
] | [
false
] | Did a bit of googling with no avail. Just wondering if there's some sort of method to do see either an electric/magnetic field/flux. | [
"Haha, see happening in front of my eyes!"
] | [
"Haha, see happening in front of my eyes!"
] | [
"YES! Get a cylindrical magnet and a long piece of straight copper tubing with just a slightly larger diameter than the magnet. First drop something non magnetic through the tubing note the time it takes. Than drop the magnet through. Prepare to be amazed. ",
"http://www.youtube.com/watch?v=30oPZO_z7-4"
] |
[
"Would we know if a distant galaxy was made up of anti-matter?"
] | [
false
] | Would there be a difference in the light or radio signals or anything? Could there be huge amounts of anti-matter that looks just like matter? | [
"If it was totally isolated, we would not know. However, if there were a part of the universe made of antimatter and the rest made of regular matter, at some point there would be an interface where we'd see a ton of annihilation events occurring, and we do not see this."
] | [
"Space isn't quite empty. it mostly condensed into galaxies and such, but some of the matter is still spread out. Antimatter dominated space would have one anti-atom per cubic meter, but it would annihilate with the one atom per cubic meter on the boundary."
] | [
"It's just matter that didn't condense into galaxies. It formed the same way the rest did. Distance isn't really an issue. It doesn't make it look dimmer. Just smaller. And galaxies are huge so that's not a problem. What do you mean by muddling?"
] |
[
"What is the cause of stereoisomerism?"
] | [
false
] | I found descriptions of what it is, two identical chemical formulas with identical bind between toms, but different geometry. I recall a bit from high school too. But i can't quite understand why would the atoms decide to arrange one what or another. Does it have to do with the electronic layer that happens to bind two... | [
"To get deeper, it can also be (and is!) performed in the lab. Stereoselective synthesis makes use of chiral catalysts or chiral auxiliaries to get more ",
" of the desired stereoisomer. It works by either lowering the energy state of the desired product (thermodynamic control) or lowering the activation energy r... | [
"How do you make sure you create one and not the other?",
"This is where it gets interesting. You really don't. For example, when making glucose from scratch in a lab, about 1/2 will be D-glucose (dextrose) and the other will be L-glucose.",
"Notice how I specifically stated 'in a lab'. In living cells, this is... | [
"But i can't quite understand why would the atoms decide to arrange one what or another.",
"This has been explained before but I'd like to word it another way. Generally, when a chemical reaction occurs, the atoms arrange randomly so that you could have either version. Atoms don't care what configuration they are... |
[
"What are the problems surrounding human cryogenises (with prospect of later resuscitation), and does anybody in the field have any insight on the steps being taken to improve the process?"
] | [
false
] | [deleted] | [
"I do not work in this field, but...",
"Freezing water produces ice crystals. Ice crystals within cells destroy them, breaking apart organelles, expanding to break the membrane, causing solutes to precipitate and so on. To deal with this for electron microscopy, people flash freeze samples, freeze cells with thin... | [
"When you speak of a survival rate it seems as though you are suggesting people have been frozen and revived. Am I misinterpreting your statement?"
] | [
"I know it's a problem for electron microscopy, because our EM guy talked about it all the time (and would show pictures of samples where freezing wasn't rapid/uniform enough and ice crystals would destroy the samples), hence the very rapid freezing by plunging things into liquid propane and then freeze-substitutio... |
[
"AskScience AMA Series: I'm Birgül Akolpoglu, a doctoral researcher at the Max Planck Institute for Intelligent Systems in Germany. I work on microalgae and bacteria-based microrobots that could one day be used to deliver drugs and battle cancer! AMA!"
] | [
false
] | Hi all: I'm interested in finding new uses for medical microrobotics, which are developed by combining biological agents such as bacteria with synthetic materials. I recently constructed "bacteriabots," by equipping E. coli bacteria with artificial components. My team and I were able to navigate the bots remotely using... | [
"How do you prevent genetic drift of the biological components?"
] | [
"Hi! I am no expert on genetics since I am trained as a Chemical Engineer, I may not be able to answer your question fully. As far as I know, genetic drift cannot be stopped from occurring since it is an event based on random chance. In bacteria, we can rather talk about mutations, which would happen over a long pe... | [
"Thank you for your questions. Here in our study, what happens is that we attach nano-sized magnetic particles to bacteria, and therefore, we are able to control those bacteria using external magnetic fields. You can imagine a single bacterium turning into a tiny magnet that can be navigated using a larger magnet, ... |
[
"How do photons (when emitted from a source) decide which direction to go?"
] | [
false
] | Many chemical processes emit a photon when they release energy. How does an individual photon from a source decide which direction to go? | [
"A similar question ",
"was asked recently",
".",
"Basically, the photon doesn't have to go in any specific direction. Instead, there is some probability distribution over all angles for where you're likely to detect the photon. And this probability distribution is not necessarily uniform.",
"If you stick a... | [
"This is really an unrelated question as the reason a laser points in one direction is that it is collimated or focused in that direction. It's not that there aren't photons starting out in other directions, they just don't make it out the aperture."
] | [
"So if I shine a laser pointer towards the sky, there is a small probability that some of those photons will not go up, but go down towards the ground instead?"
] |
[
"So if a computer can't simulate itself does that make the creation of strong AI impossible?"
] | [
false
] | [deleted] | [
"Two issues with your question:"
] | [
"Computers ",
" simulate themselves! That's the whole point of the Universal Turing Machine, that it can emulate any other Turing Machine!"
] | [
"I'm pretty sure a computer can simulate itself - just not in real time. "
] |
[
"There’s always talk about terraforming Mars to make it livable. Why can’t/don’t we do that with our deserts?"
] | [
false
] | null | [
"Hi TheKramer89 thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the fol... | [
"'Earth Sciences'",
""
] | [
"You're talking about \"desert greening\" -- and it is absolutely a practiced concept.",
"https://en.wikipedia.org/wiki/Desert_greening",
"My limited understanding is that the general economic cost of transformation (soil introduction, seeding, etc.) is relatively trivial, but the limiting factor ",
" is intr... |
[
"Why do planets, and stars in galaxies, only orbit along a single plane?"
] | [
false
] | I asked this in a thread on and was told I'd have some luck asking here. This may be a dumb question, but why do planets orbit their stars on only one plane and in one direction? Satellites don't orbit the earth on only a single plane. I guess it's got to do with centrifugal force and gravity, but I just fail to see ho... | [
"If you're talking about why the planets in our solar system tend to lie in the same plane, it is because the dust cloud that our solar system came from started with some angular momentum. This causes the dust cloud to flatten out, similar to how spinning a ball of pizza dough causes it to flatten out. So now ins... | [
"This is exactly what has happened to Neptunes moon ",
"Triton",
"."
] | [
"I guess I didn't think that it formed in that manner due to initial angular momentum. Thanks for the response, that helped clear it up.",
"So, hypothetically, if a new planet arrived in the solar system, and was trapped by the suns gravity into an orbit, it could be on a completely different plane, and perhaps ... |
[
"How do you get energy from electromagnetic radiation?"
] | [
false
] | Is this even possible, if not, why can't we? Or explain how we already do. | [
"You can harness the energy in electromagnetic radiation by absorbing it. Photovoltaic cells absorb light and produce electricity. Other systems absorb light and increase their temperature, the idea behind passive solar heating. You can take sunlight and use mirrors to focus the light to heat water and run a tur... | [
"We already do. You've heard of solar cells, right?"
] | [
"A wave of electromagnetic radiation is a photon travelling and oscillating at the wavelength of the light/radio/microwave/whatever radiation that is observed. Along with the photon oscillating, a magnetic field is oscillating, in sync with the photon, but perpendicular to the plane of the photon oscillation and tr... |
[
"Would centrifugal gravity work on the surface of an asteroid of significant mass if you tilted the floor?"
] | [
false
] | So I have this little scheme in my head for artificial gravity for a smallish colony on an asteroid. If you were to stand in a spinning in space, you would feel 'gravity' in the direction of the outside of the circle, ie. centrifugal force. If you were to put the same cylinder on the surface of an asteroid with say 1% ... | [
"The concept is very similar to that of a ",
"banked turn",
", and yes it would work, for the same reason that your coffee is not spilling when your airplane is making a turn.",
"I see one problem though: Since the centrifugal force depends both on the angular velocity ",
", there would be different forces ... | [
"Sure, there's no reason that wouldn't work in principle. You can find the angle by just adding up the vectors. Note that many asteroids are significantly non-spherical, so the gravity vector might be different in different places.",
"You might be interested in Kim Stanley Robinson's ",
". Aside from being a gr... | [
"Yes, right! (Which reminds me of ",
"this experiment",
".)"
] |
[
"Why don't energy saving CFLs work in dimmer lights?"
] | [
false
] | As the titles says, why don't those energy saving CFL bulbs work in lights that have a dimmer dial? Even if you leave the dimmer switch at full-on and never lower it, they still don't work. | [
"Dimmable CFLs"
] | [
"An engineering question, not a science question :P.",
"Dimmers work via ",
"pulse width modulation",
". They very quickly turn power on and off in pulses. Incandescent light bulbs work by heating up, so the brief pulses don't heat the filament up as much, resulting in a dimmer glow. Of course, the bulb is ge... | [
"Thx, I'm gonna buy some of those, but this being ",
"/r/askscience",
", it doesn't explain why other CFLs don't work."
] |
[
"do viruses stay in the body forever?"
] | [
false
] | obviously some do, like chickenpox or HIV, but surely the head cold from when i was 5 is gone by now, right? | [
"Finally, an askscience I can help answer:",
"There are two types of viruses: Lytic and lysogenic. ",
"The lytic viruses will invade your cells and through replication, will destroy them. This is the flu, head cold, etc.",
"The lysogenic will not do this. Rather, they will integrate their DNA into your own ce... | [
"There are various types of viruses, some are easier to get rid of than others. Some viruses simply infect a cell, hijack the cellular protein synthesis system to create new copies of itself and then lyse (kill) the cell, releasing new copies of itself to infect new cells. These types of viruses are generally more ... | [
"From your explanation about the second kind of viruses, it seems they could very much fiddle with our DNA. Do these viruses commonly cause tumours?"
] |
[
"Why is death in cyanide poisoning more rapid and fatal than amobarbital overdose?"
] | [
false
] | Hello everyone. Can someone explain why is death in cyanide poisoning more rapid and fatal than amobarbital overdose? Thank you | [
"strange question, as these two have basicly nothing in common. In short:",
"Cyanide binds to the iron in red bloodcells, this directly inhibits the oxygen transfer in the body. So cyanide suffocates you from the inside even though you can breath freely. As far as i know, there is no real antidote once you got po... | [
"Under what circumstances would someone have both access to cyanide and access to someone with the wherewithal to administer the antidote in time? Are there certain industries where both are common?"
] | [
"The most common form of cyanide exposure is smoke inhalation from house fires. The cyanide is created by the burning of many kinds of plastics and polymers. ",
"A person who has inhaled smoke at a house fire should get immediate medical attention. Hydroxocobalamin will be given at the hospital if indicated. ",
... |
[
"Knowing that the Meyers-Briggs typology is bunk science, is there a more accurate system for observing behavior patterns in people?"
] | [
false
] | A year ago, several friends got me into the MBTI stuff. Avoiding the highly inaccurate online tests and sticking with understanding the philosophy behind it, I'd discovered that it was a great system for picking out certain tendencies in people. It also helped me better understand what qualities in people I tend to pre... | [
"I wouldn't go so far as to say Meyers-Briggs is bunk science. I would personally reserve that title for some pseudo-science that is actively harmful to people's psyche and their relationships. I think of Meyers-Briggs more along the lines of a self-help book: beneficial because it encourages conversation and thoug... | [
"I know about the different cognitive functions of MBTI. The vast majority of people don't understand or use the cognitive functions of MBTI or the deeper layers of MBTI. Even though you can score in different shades of Extroversion, it is always reported either on or off. That is one of the negatives of MBTI. Peop... | [
"Sorry OP, I don't have anything to help you, but I've had a passing interest in Meyers-Briggs for a while, and I was wondering if you could suggest any resources for learning a basic introduction. (As well as the dissenting opinions you mentioned.)",
"Thanks."
] |
[
"Are there any known animals that have a sleep/wake cycle that is not 24 hours?"
] | [
false
] | I remember reading somewhere that humans naturally would be on a 23 hour sleep/wake cycle. It got me wondering if any animals have extremely different sleep/wake cycles, i.e. Awake for 36 hours, asleep for 12? | [
"Many animals have sleep/wake cycles that are ",
" than 24 hours / and/or variable. ",
"For example",
"- Grazing animals such as horses",
"Unlike humans, horses do not sleep in a solid, unbroken period of time, but take many short periods of rest. Horses spend four to fifteen hours a day in ... | [
"Also humans have been found to adjust to a different sleep cycle when there is no sun. e.g. ",
"http://en.m.wikipedia.org/wiki/Michel_Siffre"
] | [
"The four relevant terms are diurnal, nocturnal, crepuscular (active dawn and dusk), and cathemeral. The last is the one you're interested in. Animals of this least common type are active any time day or night. I first heard the term applied to the fosa (cryptoprocta).",
"So, yes."
] |
[
"Accelerative artificial gravity in zero G."
] | [
false
] | In sci-fi, often you'll have spinning ship (or spinning ship sections) to induce an artificial gravity by acceleration. In Babylon 5, you have a giant space-station whose body spins while a set of rings at either end anchor to a stationary platform across the top of the station. The station is supposed to be at a Lagra... | [
"It can be done a number of ways. Chemical thrusters work just fine, especially small thrusters spinning up a big station. If you have two counterrotating sections, they can be driven by electric motors of any sort. Flywheels could also work, but it seems needlessly complex compared to simple exterior thrusters. If... | [
"Sure, it works that way too. Have thrusters on both the stationary and rotating sections. Thrust the ring to spin it up, and thrust the other to keep the stationary part still.",
"For that matter, if you have a big electric motor and big thrusters, you could spin up the ring with an electric motor and apply enou... | [
"Unless I'm misreading you, your thoughts don't account for one moving part ",
" one stationary (non-accelerating) part. Motors and gears wouldn't work for sure, but I'm not sure exactly how flywheels work in zero-G. And presumably one would need to move between the stationary and spinning parts in some way.",
... |
[
"Why does hand foot and mouth disease (coxsackievirus) cause blisters in the hands, feet, and mouth?"
] | [
false
] | I saw a post about chickenpox in this sub and the common spots, but this made me wonder why hand foot and mouth disease (coxsackievirus A16) specifically causes blisters and rashes on these extremities. I am not well versed in virology or histology, so if this belongs in another sub please let me know (like ) Thank you... | [
"In order for a virus to infect a cell, it has to be able to bind to one or more receptors on the cell's surface (often proteins on the cell's surface, but can be other things like specific lipids in the cell membrane, or carbohydrates on the membrane's surface) and use them as a foothold to somehow deliver its gen... | [
"Sorry if I didn’t make this clear. I’m NOT asking about WHY the disease was named this. I’m asking WHY blisters form where they do with this disease rather than ALL OVER like smallpox and chicken pox"
] | [
"Would you know if cells on the retina or other parts of the back of the eyeball can be affected by this virus? In June of last year, I caught a pretty good case from my 2 year old grandson. I ended up with lots of spots on my face, hands, and feet. About a month after I got symptoms, I noticed a new blind spot in ... |
[
"[Bio] What caused so many ancient mammals to have sabreteeth?"
] | [
false
] | I always wondered how so many (mostly extinct) mammals had sabreteeth. Was there a common reason that they developed? | [
"It's an example of convergent evolution. Which means that a number of disparate lineages all settled on the same solution to similar problems. In this case the problem is \"How can I slit that thing's throat quickly and efficiently?\" ",
"And the solution is giant knife-like teeth. "
] | [
"How about three highly disparate species? ",
"Wings have evolved in birds, bats and insects. ",
"How about at least ten?",
"Hard outer shells have evolved in mollusks, turtles, arthropods, echinoderms, brachiopods, mammals, dinosaurs, fish, corals, diatoms, and more. ",
"We actually see conver... | [
"Follow up question: Why don't we see sabreteeth in the present day? What factors encouraged them in past periods?"
] |
[
"Clarification of anatomical differences between Homo sapiens idaltu, homo sapiens sapiens, and Homo rhodesiensis?"
] | [
false
] | Wikipedia writes the following: An exact description was made, by its discoverers, of Homo sapiens idaltu:[1] On the limited available evidence, a subspecies of Homo sapiens distinguished from Holocene anatomically modern humans (Homo sapiens sapiens) by greater craniofacial robusticity, greater anterior–posterior cran... | [
"Here's how it goes:",
" (HSS): That's you, and me, and all the Redditors who aren't actually dogs.",
" (HSI): An early variant of HSS, possibly a direct ancestor. Maintains some archaic features that distinguish it from HSS. I'll explain them below.",
" (HR): The most difficult to classify. Pre-dates both HS... | [
"Craniofacial Robusticity: Essentially the thickness of the bones and size of the muscle attachments.",
"Craniofacial Region: Your face, discluding your lower jaw (well, pretty much anyways).",
"Anterior-posterior cranial length: The length of your skull from front to back.",
"Glenoid-to-occlusal plane distan... | [
"And suddenly everything makes sense!"
] |
[
"Why are there different types of meat? Red meat, white meat, etc.?"
] | [
false
] | null | [
"So the color of the meat tells you what kind of movements the animal makes. Myoglobin is a protein with higher affinity for oxygen than hemoglobin and is found in the muscle which allows the oxygen from the blood to be passed to the muscle.",
"Cellular metabolism is split into 2 different flavors, non aerobic (g... | [
"This may not be the whole answer, but the ",
"amount of myoglobin in the meat",
" is probably one of the main contributing factors."
] | [
"Just to clarify, myoglobin is not just 1/4 of a haemoglobin molecule. Haemoglobin is a four subunit protein (2 alpha and 2 beta subunits) and myoglobin is ",
" in structure to one subunit. However it is not exactly the same. For example, the parts of the subunits of haemoglobin that face each other have hydropho... |
[
"Are we getting close to designing spacecraft where large parts of the craft don't have to be discarded after launch and before reentry (for example the shuttle loses the large fuel tank)?"
] | [
false
] | null | [
"The reason they detach large parts is because otherwise the craft has to supply enough energy to take the empty bits up to orbit. There is no reason to do that - it means more fuel in the later stages. to lift that later fuel up, it means you need even more fuel in the early stages. So now the fuel tank for the... | [
"Discarding large parts of the craft isn't necessarily a disadvantage. Especially if they can be recovered (like the solid state booster rockets), but even the main liquid fuel tank of the space shuttle being lost was still the best option at the time, and the next design could also use something like it.",
"The... | [
"This was the intention for Single Stage to Orbit vehicles (SSTO) ",
"http://en.wikipedia.org/wiki/Single-stage-to-orbit",
" the original Space Shuttle program was envisioned to create technologies that would eventually lead to SSTO development. The Skylon as mentioned is an example of a possible SSTO vehicle.... |
[
"Why does putting pressure on an injury reduce the pain."
] | [
false
] | [deleted] | [
"Your brain and your spinal cord probably do something called \"sensory gating,\" in which it seems that pain information from different nerves have to pass through the same neural \"gate\" in the spinal cord to get further. When you, say, rub your sprained ankle, then your brain prioritizes the pressure informatio... | [
"Had neuroanatomy last year, here is the real answer: there is a positive feedback loop which lessens the amount of pain you feel when you put pressure on the wound. This is evolutionarily advantageous as it will help stop a hemorrhage when you are injured. (BTW, pretty much the only useful thing I learned in the... | [
"This is true. The phenomenon is called \"presynaptic inhibition\". The synapse of one neuron may communicate with the presynaptic region of another dendrite from an adjacent neuron or even to another dendrite on the same neuron. This is in contrast to the more typical point of communication- that is a synapse t... |
[
"Does wind speed effect a ram-air canopy's decent rate?"
] | [
false
] | So people are saying that it doesn't. People are saying that flying into 12 mile an hour winds and 24 mile an hour wind should produce the same decent rate. this seems completely messed up based on what I know of how wings work and law of conservation of energy. more energy int the general system cant produce the exact... | [
"Now would the same decent rate occur at two different constant wind speeds would, for simplicity, head winds at 40mph and 20mph still produce the same decent rate on the glider?"
] | [
"Absolutely. If your vertical speed is 15 ft/s in no wind, it will still be 15 ft/s in 20 mph winds, or 40 mph winds, or any other feasible wind speed."
] | [
"Ok, can you tell me why that is though? since it is demonstrable that wind speed has an affect on lift ",
"http://quest.nasa.gov/aero/planetary/atmospheric/lift_experiment/index.html"
] |
[
"How do those mountains of stone columns form?"
] | [
false
] | I assume it has to do with lava potentially but I'm not really sure. I took a picture (sorry I just snapped the pic off my TV) so my horribly phrased question can be easier understood. I'm pretty sure they're not man made but hoping I can get better answers. I'm not googling the right words so I'm not coming up with an... | [
"This kind of texture is most often found in basalt. Basalt is an igneous rock formed from magnesium- and iron-rich lava flows. When a big mass of lava covers the surface of the Earth, it generally cools most quickly from top to bottom (where the old surface of the Earth was), for obvious reasons - the top is exp... | [
"I would assume this has formed much in the same way as the Giant’s Causeway. That formed via the result of intense volcanic activity when highly fluid igneous rock (basalt) intruded through chalk, cooled and contracted giving rise to horizontal fracturing similar to drying mud. "
] | [
"Thank you for the incredibly informative answer! "
] |
[
"Why does Moana Kea have so many cinder cones?"
] | [
false
] | Just came back from a trip to Hawaii, and we drove over the Saddle Road, and I was really surprised by how many cinder cones are scattered all over the south side of Moana Kea. By contrast, there are comparatively few on the north side of Moana Loa. I've spent a lot of time around volcanoes in the PNW, from Mt. Baker t... | [
"Mauna Loa and Mauna Kea are both shield volcanoes formed by the Hawaiian Plume, but they are in different phases of life for volcanoes of this type. Mauna Loa is in active shield building, where you have large volumes of silica-poor lavas with low viscosity with frequent eruptions. The eruptions occur both from th... | [
"There are at least 30 cinder cones that have come out of vents in my lifetime there in Hawaii. The volcanic system is very active and over geologic time you would expect to see lots of them. The ones you see at the saddle road area have not experienced ocean erosion and so once they pop up they stay for a long tim... | [
"Can you explain more about the Kea/Loa trends? Kilauea is active (like Mauna Loa), so presumably you are not referring to the temporal evolution of silica content."
] |
[
"How does the energy of a nuclear fusion reactor scale according to its size?"
] | [
false
] | Does it scale according to volume? For example, if you have a reactor that fits a volume X of hydrogen, and another that fits 10X, would the energy generated by the second be 10 times the energy produced by the first one? Or does it scale exponentially or by some other factor? (assuming the reactors have the same effic... | [
"Assuming all other factors, such as pressure and temperature, remain constant, the total reaction energy is indeed proportional to the volume of the fusion plasma.",
"However, the energy loss through the reactor walls is proportional to the surface area of the reactor vessel and since the surface area scales mor... | [
"So it scales as n",
" - n",
"?"
] | [
"Yes"
] |
[
"How do creatures know or learn what they are attracted to?"
] | [
false
] | I was thinking about this the other day. We have mirrors, we know we are humans, we are attracted to humans. How does a low intelligence creature know it is trying to copulate with a compatible mate? Could this affect evolution and the mutation of new species? | [
"Some know, some learn. There are studies showing that a baby seagull will instinctively attack a red dot on a pretend beak that looks like its mother's. This behaviour has been shown in chicks that have not been raised by gulls, and so must be innate. Other animals will attempt to mate with anything: my dog quite ... | [
"Are you sure the dog isn't simply masturbating?"
] | [
"Humans are attracted to (feel connected to) other humans before they can identify themselves in a mirror (circa a year). This is because of the environment we grow up in is directly condusive to strengthening that particular effect. You are probably aware of cases where x species was raised by y species. This warp... |
[
"If you were sleeping in an immediate environment that was extremely loud, would a sudden, immediate and total quiet wake you up?"
] | [
false
] | null | [
"I came here to say this, my grandfather was a submariner and retired, he had to have white noise constantly to sleep. When the power would go out (We lived in the mountains.) He would come awake like a gun shot. If memory serves, the sudden lack of pressure causes a vertigo moment where the subject has a feeling o... | [
"Do you have a source for this or is this just speculation?"
] | [
"I could tell you how a pussy feels too, but you'd probably yammer on about \"scientifically calling it a vagina\". "
] |
[
"If we were to discover amino acids on Mars, would this suggest that life on Mars was a near certainty?"
] | [
false
] | What characteristic about amino acids along, is single evidence enough that life is nearly certain?? If we discovered amino acids/proteins instead of water. | [
"Well, it certainly would bolster the case; but I don't believe it would slam dunk it for local martian life though. Amino acids such as adenine can form abiogenically and have been identified in interstellar space and glycine was recovered from cometary material by ",
". I believe there was also some evidence of... | [
"No not at all. Because the vacuum of ",
" grouped in huge clouds. Small amino acids can form naturally in space from gas clouds and on planets without forming self replicating lifeforms. Medium sized amino acids are less common in space, but we might find them as well, proving nothing. large amino acids are not ... | [
"Amino acids are very simple molecules, made of just a few atoms. They form spontaneously very easily when the necessary precursors are present.",
" which is what life is all about, are ",
" molecules made up of hundreds or thousands of amino acids chemically bonded together into a big polymer.",
"Finding ami... |
[
"What determines the speed at which memories are recalled?"
] | [
false
] | Not the difference between long and short term memories, but why do the rates of recollection I have for long term memories of nearly the same importance vary in speed? | [
"One model of memory essentially posits that you have a network of neurons which participate in the storing and recollection of particular events or facts. The more nodes in this network are activated during recall, the faster recall. A lot of things influence how many nodes are activated:"
] | [
"Sorry if this is inappropriate for the subreddit, but your description sounds a lot like ",
"Freenet",
" and I wonder how similar the processes are. In Freenet, data is passed around and sometimes duplicated as it moves throughout the network. When retrieving data from the network, you often get different bloc... | [
"Conceptually quite similar, though the mechanisms and media obviously differ substantially."
] |
[
"[Math] Where did the notion of 'cross product' arise?"
] | [
false
] | I am a student studying physics, and I had familiarized myself with the notion of carrying out a cross product and the applications in problem solving. I was working on a systems of particles problem, and I realized that I never really questioned what a cross product is (beyond how it is defined and their properties) ... | [
"Josiah Willard Gibbs",
" developed the notion of both the dot and cross products. He was looking for an easier mathematical approach to quaternions. So he came up with the idea of representing lines as vectors, and the rules for multiplying vectors with either a dot or cross product.",
"It's important to note ... | [
"Have you look at the ",
"history section",
" in the Wikipedia article about cross products? It's also got some good references if you want to go further."
] | [
"Wow, how did I miss this? I was on that page earlier today attempting to answer my own question. I guess I skimmed a little too quickly. Thanks for calling this to my attention."
] |
[
"Do Magnetic Fields Instantly Appear or do they Propagate at the Speed of Light?"
] | [
false
] | null | [
"Electric and magnetic fields always propagate at the speed of light. That's what light is made of, after all. When we talk about the 1/r",
" distribution for a static charge for an electric field (or the magnetic field of a bar magnet) we're assuming that the charge has existed \"forever\" in the same position. ... | [
"As ",
"/u/Snuggly_Person",
" notes, magnetic fields do not instantly appear. If they did, you could use this to break causality and propagate information instantaneously. ",
"To elaborate slightly, at a point ",
" at time t, the electromagnetic fields come about from the history of moving charges through a... | [
"A useful tip for understanding what may or may not travel faster than light: If you can use it to send information, it can only travel as fast as the speed of light, if it is totally random and cannot be used to send information, then it has the potential to travel faster than light. For example, if you and a fri... |
[
"How are therapeutic genes loaded into viral vectors?"
] | [
false
] | In gene therapy, a viral vector is loaded with a therapeutic gene for delivery to a cell where it then inserts and can begin producing a target protein. I've searched the literature and can't find any experimentals or explanations on how to actually package the therapeutic gene into the vector. Could someone explain ... | [
"Not my specialty but i'll get the ball rolling.",
": By use of classical cloning techniques. Restriction enzymes, ligases, phosphatases, much like inserting a vector into a bacterial plasmid.",
": The nucleic acid construct can be transfected into certain model (and competent) organisms by electroporation or l... | [
"I do this once a week. \n1. The gene is produced from genomic cDNA and amplified via PCR. \n2. The product along with a \"packaging plasmid\" (pCDH) are digested with restriction enzymes. The packaging plasmid usually has a promoter (CMV) that will cause the gene to expressed in a human cell and antibiotic resista... | [
"There are basically three steps in this, that you might call \"loading\". The example here is a rAAV vector.",
"The first to place the sequence (the gene) into a suitable vector backbone. The gene is coding sequence, so no introns, meaning that every nucleotide will get translated straight to RNA to protein. Thi... |
[
"Why do some fluorescent light bulbs and TVs seem to flicker when I look at then through my peripheral vision?"
] | [
false
] | [deleted] | [
"The retinal cells for your perpiheral vision are optimized to see change, whereas the ones in the center of your vision are optimized to see color. ",
"The bulbs and TVs really are flickering all the time, but only your peripheral vision can see this rapid flickering."
] | [
"Lights, certain TVs and CRT monitors actually do flicker. The reason you only notice when they are in your periphery is because of the organizational structures in your eyes.",
"Your eye has two different type of photoreceptors: rods and cones.",
"Cones discern color, while rods are sensitive to intensity(1)--... | [
"Because they are flickering. Fluorescent bulbs flicker at 100 or 120 Hz, depending on where you live. CRT type screens also flicker at their refresh rate, which is determined by the application."
] |
[
"Can someone explain how this image is possible?"
] | [
false
] | This image - How is the rider tilting the bike so that it is nearly parallel to the ground, without toppling over? Is this possible with a normal 2 wheeled vehicle on a normal road? What I mean to ask is that, is there anything special about the tyres, about the road, about the speeds of such turns? | [
"They do touch the ground. They have solid pads on the knees called knee sliders, usually made from plastic or sometimes titanium, to protect them."
] | [
"First off, the tires on MotoGP bikes have a much, MUCH larger contact patch than normal road motorcycle tires, so they are able to maintain their grip on the road over a much wider angle.",
"Secondly, the reason he can do this is due to angular momentum, which is more commonly known as the gyroscope effect. When... | [
"A low center of gravity, a carefully made turn, and centripetal acceleration. As he is turning, the bike wants to go straight, meaning that he keeps his balance, even as he nearly touches the ground."
] |
[
"Do Climate Change denialists actually have any kind of real science to stand on?"
] | [
false
] | Like have any anti-climate change research been published. Does there exist any controversial facts that don't quite fit into climate change. Obviously, climate change denialism is often seeded by cherry-picking, junk science and bought-out scientists. I'm just wondering if any of their claimed facts are true. | [
"Your question is ambiguous. Pretty much everyone agrees that since the beginning of the previous century Earth has warmed on the order of just under a degree Celcius. If by \"climate change\" you refer to AGW, or anthropogenic global warming, it is mostly accepted that CO2 causes some amount of warming but the mag... | [
"Even Christopher Monckton admitted (at least a few times) that the climate is in fact changing, but not, he believes at a level that warrants concern.(as stated above)"
] | [
"While we're on the subject, some of my friends periodically bring up this Climategate business and the allegedly deleted \"raw data.\" Rather than pointing them to the investigations which mention being able to acquire the raw data online, I'd like to just point them directly to said data. I see that I can downl... |
[
"Would it be more efficient to build Spaceships in space?"
] | [
false
] | Would this make it possible to skip the step of launching a ship into orbit? Would this be possible at all? | [
"If we get to the point of having raw materials and the means to process them into components already in orbit (space factories, space stations, space habitats, etc.), it would definitely be more efficient to keep things in orbit if we expected them to need to be there later.",
"That said, that's a large up-front... | [
"This answer assumes a few things that aren't ",
" true. The main thing that sticks out is the notion that the spaceship you want to build is capable of getting into space. ",
"For example, it was cheaper to build the International Space Station in orbit. It's way too big and not at all capable of atmospheric f... | [
"Actually this has been done with MIR and ISS.",
"Ok, it actually depends on what you call \"build\". Technically, they were built on Earth and ",
" in orbit. The greatest advantage is that it can be taken up there without the need for a very big launcher, by splitting it into several small launches. For instan... |
[
"Laser Behavior"
] | [
false
] | [deleted] | [
"The light which travels through the plastic is simply the light from the laser which passed through the plastic unchanged. The more interesting case is the different color light emitted from the plastic. In this case, photons from the laser excited the dye molecules in the plastic, which then re-emitted lower ener... | [
"High-Curious is right. I would just add that the process is called fluorescence if you'd like to google it."
] | [
"An orange dye would not emit blue after absorbing a blue photon, it's emission would be orange. The energy structure of dyes allow them to have very large absorption bands that extend from roughly the peak of the emission curve to well into the UV. Molecular fluorescence doesn't necessarily follow the same rules a... |
[
"Is it known, with relative certainty, that plants and animals have a common genetic ancestor?"
] | [
false
] | Or, I suppose stated differently, is it thought that biogenesis occured only once/in a single location on Earth - or is generally accepted that biogenesis could've/likely occurred independently in multiple geographic locations throughout Earth's "early-ish" history? | [
"Yes, all life appears to have come from 1 abiogenetic event - or if not, several incredibly similar events producing incredibly similar organisms along the same lines (i.e. carbon-based with nucleic acids as the coding component). Given that the hypothesis for creating such life would require lightning to strike a... | [
"Ah, thank you - this gets to the heart of my question - whether the conditions for a Miller-Urey type event would've been so rare as to have been unique (or nearly unique), naturally, in biological history.",
"If I could go just a bit further - are there any other theorized (perhaps silicon-based?) base chemistr... | [
"Yes ",
"silicon-based life has been proposed",
", as have sulphur and nitrogen. Generally anything that can form 3 or more stable bonds in one way or another is viable for life (at least theoretically). The solvent may need to be different, but the key thing to consider is whether it works structurally."
] |
[
"Why does fire need oxygen (I mean oxygen specifically, instead of other things) and why does the common \"burning\" reaction seem so universal?"
] | [
false
] | Fire is things reacting with oxygen. Why don't we get similar effects happening with, say, nitrogen (or any other substance for that matter)? And why does it seem to work on so many things in the same way? | [
"Any strong gaseous oxidizing agent could in principle support combustion just like oxygen. For instance, chlorine. ",
"http://www.youtube.com/watch?v=MtygiCwnEzw",
"You could even do a reverse experiment where you have an \"atmosphere\" that is mostly something like propane, and pipe in a \"fuel\" of oxygen. T... | [
"Fire is a reduction-oxidation reaction, so technically any so-called redox pair is similar to fire, and their are thousands that we know of. ",
"What makes oxygen particularly special is three things. First, it is very oxidative, with a reduction potential of ",
"1.23V",
", which is pretty high on the list o... | [
"This is correct. I do want to add a bit about point 3. In a typical combustion reaction, the reaction is not catalyzed by temperature (at least not directly). Temperature cannot catylize the production of singlet oxygen from triplet oxygen. Instead it is catalyzed by the production of free radicals. So at hig... |
[
"How many years of driving a Prius, or similar, would it take to offset the carbon emissions generated in the manufacturing of the car?"
] | [
false
] | null | [
"Isn't the correct answer never since the act of driving a car produces more emissions? ",
"I guess you are asking if I buy a new Prius or an second hand car which will have the lowest emissions, but even that is flawed. What if I buy a secondhand Prius?",
"I think the important part of the Prius or the like is... | [
"Man, I really liked the ",
" of your comment.",
"If you really care about the carbon emissions, don't drive a car.",
"I don't like the binary reasoning here, that someone has to either never drive, or stop caring about carbon emissions. "
] | [
"Every car has some initial manufacturing cost, in emissions, and some running cost, in emissions. OP is asking for a comparison between three options:",
"OP is asking if the long-term benefit of option 2 over option 1, is actually less significant than the long-term benefit of option 3 over option 1. You seem to... |
[
"Do we have any solid theories about how organisms with vastly different numbers of chromosomes came about in the context of evolution?"
] | [
false
] | null | [
"In the future please don't resubmit your question. We hold all posts for moderators to check and make sure they meet our guidelines. It is normal for submissions to take some time to show up on the sub.",
"Your other submission has been released."
] | [
"I've never submitted something just once and got an answer. Yall need to work on your algorithms if you want people to not do this."
] | [
"There's no algorithm, there are a bunch of people volunteering their time to go through through everything. Submitting things multiple times doesn't make your post get through faster. It just makes more work for us. ",
"If your post doesn't show up after a few hours you can send us a modmail and we'll look into ... |
[
"Why does protein cause foamy urine?"
] | [
false
] | Tried a quick Google search, but just turned up vague "protein reacts with air to make foam" and wanted more specific reasons why proteinuria would manifest as foamy urine. | [
"So when proteins are whipped up by mechanical forces (stream of urine hitting toilet water, or making a meringue using egg whites) the protein gets denatured, meaning that the three-dimensional structure of the protein is destroyed. You are left with long chains of amino acids which are all charged differently bas... | [
"Thanks, that makes perfect sense!"
] | [
"Well although foamy urine would most often be caused by excess protein in the urine, it could potentially also be due to excessive force while urinating or maybe a change in diet that includes a ton of protein. People can also have a significantly higher amount of protein in their urine at the first morning void (... |
[
"can you explain, in layman's terms, how particle accelerators actually work?"
] | [
false
] | Sciencebabes, I have a question. I understand what particle accelerators are, and what they are looking for. I love reading about the experiments they carry out. But what fascinates me the most, and what is rarely covered in the literature, is that behind every machine and every experiment there is an army of machini... | [
"No, it's good! And thank you. I have a pretty good handle on the theory, I'm mostly just curious about the machines themselves that make this sort of thing work. "
] | [
"I'll let the experts explain, I just want to recommend a book: The god particle by Leon Lederman. It's amazing and very entertaining and it's all about particle accelerators. (Lederman was the director of Fermilab and took part in the discovery of the muon neutrino and the bottom quark)"
] | [
"Thank you! I will be sure to check it out."
] |
[
"Why do we put satellites in orbits that decay?"
] | [
false
] | I sometimes read about satellites' orbits decaying, because they experience some drag from the earth's atmosphere (e.g. says that the Hubble will fall to Earth around 2024). Why do we place satellites in these orbits, knowing they're unstable? Would it be that much harder to place them in deeper space where orbits can... | [
"All good things must come to an end.",
"Geosynchronous satellites are generally far enough away to be stable in their orbits for a long time. Indeed America has for some time required satellites launched to that orbit be able to boost themselves into a higher \"",
"graveyard orbit",
"\" once their service li... | [
"They usually have small ",
"RCS",
" thrusters for station-keeping (so the right parts are pointed to earth and the solar panels are pointed to the sun).",
"A larger thruster like ",
"IUS",
" is often used only once. Thrusters for moving to different orbits during the lifetime of a satellite are possible ... | [
"but in space you would not need as much fuel. So, say, two small fuel pods could have been attacked to each side. Pod a used for goings past the ISS orbit and pod b to return to orbit entry for glide down. ",
"I really do not understand why we scrapped the shuttle. Yes, they were old, but in 30 years there was o... |
[
"How random is our universe?"
] | [
false
] | What I mean by this question is say: I turn back time a thousand years. Would everything happen exactly the same way? Take it to the extreme, the Big Bang: Would our universe still end up looking like it is now? | [
"It's not random at all; there are well-defined laws that govern how the state of the universe evolves from instant to instant. However, some of those well-defined laws are ",
" rather than ",
" That means it would be impossible to predict with certainty, even if you had perfect knowledge, how the universe woul... | [
"Cosmology grad student here. ",
"If we wound time back to the Big Bang, holding the laws of physics as constants for this Universe, and then fast forwarded to today, the Universe would look identical on the largest scales, i.e. the distribution and density of galaxies and galaxy clusters would be the same (scale... | [
"Meaning that the universe ",
" random to an extent?"
] |
[
"How could I calculate the maximum size of a water balloon before it bursts?"
] | [
false
] | I've got a BSc in Physics and I'm wondering what the maximum size of a water balloon or any other liquid filled spherical object would be before it breaks under it's own weight, depending on the strength of the shell material. How do I calculate the pressure on the shell and relate it to it's mass and volume? | [
"If we're doing this \"spherical cow\" style then it should be possible, otherwise you'd need to work the problem for a class of specific balloons and probably study them extensively.",
"http://www.damtp.cam.ac.uk/lab/people/sd/papers/2014/LundDalziel2014_JFM756.pdf"
] | [
"The comments treating this as a hoop stress or pressure vessel problem are missing an aspect that may or may not be trivial- the strength of the balloon material as it is strained will vary with both the amount of strain applied and the rate at which it is applied . The balloon is probably latex or something simil... | [
"I would think the failure would occur when the hoop stress in the balloon exceeds the strength of the material. It should be a property of the volume filled rather than the weight inside. For example, if you fill it with air instead of water, you won't get the same mass of air in before it bursts as you would wate... |
[
"How do warm-blooded animals create their own heat, and why can't/don't cold-blooded animals do this?"
] | [
false
] | null | [
"Warm-blooded creatures, like mammals and birds, try to keep the inside of their bodies at a constant temperature. They do this by generating their own heat when they are in a cooler environment, and by cooling themselves when they are in a hotter environment. To generate heat, warm-blooded animals convert the food... | [
"The heat is generated by all of the biochemical reactions carried out by cells. The liver is the main contributor of heat since it carries out hundreds of reactions. Every time that a \"fuel food\" - protein, carbohydrate or fats - is broken down, heat is released as a by-product. The actual product of this \"tiss... | [
"There are many advantages to being warm-blooded. Warm-blooded animals can remain active in cold environments in which cold-blooded animals can hardly move. Warm-blooded animals can live in almost any surface environment on Earth, like in arctic regions or on high mountains where most cold-blooded animals would hav... |
[
"why my flight wasnt on a straight line?"
] | [
false
] | i took a flight from america to japan. the flight path was: west coast going north, following canada and alaska coast, then going down in russian coast to japan. instead of a straight line trough the pacific | [
"In other words, your flight was straight, your map is not :)"
] | [
"It was, or fairly close to it. Your plane probably followed a ",
"great circle",
". On flat projection maps, these often don't look straight (unless they're along the equator or directly North-South), but they are the equivalent of \"straight\" lines for lines on spheres. It may have veered away from a true... | [
"Also, on the return flight, you actually fly more of a 'straight' path back, and the flight a couple hours shorter. ",
"Another thing that people aren't mentioning is tailwinds. the ideal solution is to fly in a path where there is tailwind (wind pushing you in the direction of travel) This helps a lot with f... |
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