title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Are there any living organisms that can change the DNA of other organisms?"
] | [
false
] | You'll often see this in science fiction or horror, where an animal will bite/cut/wound/etc another, which will change their DNA and cause wacky things like superpowers (Spider-Man) or turn them into monsters (Prometheus). Obviously it wouldn't be this extreme, but is there any precedent of organisms changing the DNA of other organisms in real life? (Retroviruses can insert themselves into the genome of their host, but they're not really alive so I don't know if I'd count that) | [
"Well, if we're not counting viruses... there are parasitic bacteria like ",
" that infect plants, and inject a small piece of DNA (a plasmid) into their host plant's cells. This plasmid will integrate into the host's genome, and carries genes for things like growth hormones, that will trigger the formation of a ... | [
"There are parasites that hijack their hosts - e.g. ",
"Apicomplexans",
" and ",
"Ophiocordyceps",
" - but not by changing the host's DNA. They change the DNA ",
", which means they can take over the protein-making machinery and have the host cells do their bidding.",
"Not quite an answer to your questi... | [
"To add to what has already been said, parasites can also change their host's behavior or physiology without messing with its DNA. To increase their own reproductive success, of course.",
"The ",
"lancet liver fluke",
" sends one of a group of sibling worms (so it makes sense genetically) to bore into an ant'... |
[
"Is Magnetism just a manifestation of relativistic phenomena?"
] | [
false
] | Does the magnetic field truly exist, or is it purely due to the contraction/dilation of lengths due to relativity? What about in the case of Electromagnetic waves? I know that in EM waves the electric and magnetic fields are always perpendicular, but I'm having trouble comprehending how a truly distinct magnetic field can exist. | [
"Well, the fact that electromagnetism doesn't really work without special relativity can be shown pretty easily (with modern hindsight). The definition of whether something is an effect of SR is whether it still exists at all in the limit c -> infinity. In electromagnetism, the vacuum permittivity and permeability ... | [
"This is not correct. It is not possible, in general, to eliminate the magnetic field by changing reference frames."
] | [
"It is interesting, though, that ",
" you can get rid of a magnetic field, but you can ",
" get rid of an electric field. ",
"For example, a charged rod only produces an electric field in its rest frame, but produces an electric and magnetic field in a frame moving along its length. "
] |
[
"If the mass of an object was somehow zero would it be possible for it to travel at, or faster, than the speed of light?"
] | [
false
] | null | [
"i believe that particles with no invariant mass (such as photons) can only travel at the speed of light. there is no compelling evidence to suggest that there exist particles, massless or otherwise, that can travel faster than the speed of light."
] | [
"I think theoretically it'd have to have ",
" mass to travel backwards through time, not negative mass."
] | [
"It's \"theoretically\" possible by butting in imaginary values for the mass of particles in some Special relativity equations, but there's no experimental evidence that suggests that there are any particles with such properties. "
] |
[
"Are the divisions of sound frequencies into musical notes arbitrary or do they correspond to something in nature?"
] | [
false
] | null | [
"The frequency ratio between notes are what matters, not necessarily the absolute frequency. Specific ratios of frequencies sound nice to our ears, for example, two notes an octave apart have a frequency ratio of 2. A fifth has a frequency ratio of 4/3. Why these particular ratios sound nice has to do with superpos... | [
"Here is a longer explanation of the Pythagorean scale, where the whole musical scale is based on 3:2 ratios.",
"https://en.wikipedia.org/wiki/Pythagorean_tuning",
"This sort of tuning would work well on a simple instrument with limited range, but breaks down if you try to change key or shift up or down by more... | [
"They're not arbitrary. They're a pragmatic approximation of small integer frequency ratios. ",
"The \"pragmatic\" part is the equal division of the octave, which was done to make it easier to play in any key. ",
"12 notes per octave were chosen because it ",
"approximates the most consonant natural",
" ... |
[
"How does the air inside of a tire (or other rotating body) behave? Are different zones of air pressure created throughout the tire, or does the air remain evenly spaced?"
] | [
false
] | null | [
"Because the rotation of the tire is slow compared to the speed of sound of the air in the tire, the pressure changes propagate much more rapidly than the tire is rotating. As a result, the distribution is essentially uniform throughout.",
"The inertial effects that ",
"/u/ninja_pigLP",
" mentioned are presen... | [
"As the tire spins, centrifugal force (caused by the outward inertia of the air in the tire) causes an increase in air pressure in the air farthest away from the center of the tire, wile causing a decrease in the air pressure closest to the center of the tire rotation. This is similar to how air pressure changes du... | [
"Apologies but could you give a more accurate formula for that? Im not familiar"
] |
[
"What exactly is dark matter? Is that what we would call the space in between our atoms? If not what do we call that?"
] | [
false
] | null | [
"We can tell how much stars and gas there is in galaxies by looking at their brightness. We can tell how heavy galaxies are by seeing the speed at which they orbit, and looking at the deflection of light through and around them. The amount of mass from the stars and gas is only about 10-20% of what is necessary to ... | [
"No, because black holes are very localized sources of mass and dark matter is very diffuse. Even the supermassive black holes at the centers of galaxies only make up a small fraction of their mass, often less than a percent."
] | [
"As the other comments here have discussed, dark matter is just a name given to matter that we don't see but that needs to be there for astrophysical observations to make sense. There are ",
" of observations that all point to a need for dark matter—that's an essay in itself, so I won't go there for now. Suffice ... |
[
"Why is our galaxy relatively flat rather than a big cloud of stuff?"
] | [
false
] | null | [
"Galaxies ",
" sphere-like in shape. Here is a diagram of the ",
"dark matter halo",
" of a galaxy. Notice how the halo covers the flat normal matter of galaxy, making an ellipsoid shape. Considering that dark matter makes the vast majority of the matter in a galaxy, we can't just ignore it when we talk about... | [
"Great answer. Thank you. :)"
] | [
"i'm pretty sure your description of how ellipticals form isn't quite right. ellipticals don't eventually settle down into spirals as you suggest. it's the other way around, ellipticals are thought to form through repeated mergers of different galaxies, for instance when 2 spirals merge most of the angular moment... |
[
"Could someone please explain how substances like activated carbon and aerogel can have a greater surface area than a basketball court in just 1.0 gram of material?"
] | [
false
] | This probably has a simple explanation, but I'm having a hard time wrapping my head around the geometry. | [
"The reason aerogels and mesoporous materials like activated carbon or silica have such high surface areas is because they have very very porous structures, with very very tiny holes, and trying to imagine such a small thing is where most people trip up. Instead of trying to imagine boreing tiny holes in a material... | [
"I'm not sure about carbon or aerogel, but your lungs have a similar surface area. The lungs branch down in to the small alveoli. This allows for a huge amount of lung/air contact, which allows us to breath like we do. I'm guessing it's something similar."
] | [
"Well done, thanks for the explanation!"
] |
[
"Anyone else feel like the Bill Nye saying he doesn't believe GMOs are a good idea but then publicly investigates and attempts to learn about them was like him saying, \"Science, this is how you do it.\"?"
] | [
false
] | null | [
"This post is better suited for ",
"/r/AskScienceDiscussion",
"."
] | [
"Ok thanks, I'll transfer it "
] | [
"This post is better suited for ",
"/r/AskScienceDiscussion",
"."
] |
[
"Why does a snow flake form on what appears to be a 2 dimensional plane?"
] | [
false
] | null | [
"Hey there, I'm an undergraduate gen physics major. This is really more of a physical chemistry question but seeing as its been 8 hours I'll try to help out. ",
"I was recently reading something saying that it has a lot to do with the specific atomic structure of the water molecules. Water is two hydrogens and a ... | [
"No, there are a lot of different ways they can snap together on the atomic level. This is why every snow flake is so unique. "
] | [
"Is this pertaining to water's \"bent\" molecular structure and that it's planar? (Err...not sure if the electron pairs on the oxygen make it planar or not...plz correct.)"
] |
[
"What computer programming language would one use to create a new programming language?"
] | [
false
] | null | [
"Before stating anything else, I should point out that programming languages are not inherently based on any implementation, in the sense that you can in principle come up with a programming language but never actually write a computer program to actually compile programs for it. Thus, until you actually decide to ... | [
"I have to say that compilers that are written in their own language just make me smile. Something about a system capable of producing itself is kind of magical and fun.",
"*I know its not magic. I am a programmer. I just like a little whimsy."
] | [
"Agree. In general, most new language interpreters and compilers are written in C or C++ until they are mature enough to be efficient while self-hosting (compile themselves). This has been true for most of the major languages in use today. This is generally due to existing runtime libraries, speed and the penetrati... |
[
"Just finished the Chernobyl series on HBO. Could someone explain what positive and negative void coefficients are and why they exist? And what about a reactor design can make such a dramatic difference?"
] | [
false
] | null | [
"Getting some definitions out of the way, the ratio of the number of neutrons available for fission in one generation of the chain reaction to the number available in the previous generation is called k",
". This quantity determines the behavior of the fission chain reaction. If k",
" > 1, then the system is su... | [
"It’s very difficult to make ",
" of the coefficients of reactivity simultaneous negative. Usually it’s a tradeoff. Even if some are positive, but very small in magnitude, the system is technically unstable, but if the instabilities grow on timescales much longer than it takes for controls to take over, then the ... | [
"Awesome, thank you! Is it know what about the RBMK design made the void coefficient positive vs. other reactors that had negative coefficients? Is it challenging to make it have a negative void coefficient and this is why the Soviet Engineers couldn't figure it out?"
] |
[
"Is there a way to measure pain objectively, instead of asking the victim to describe it?"
] | [
false
] | Inspired by : I think one of the problems that non-drug-seekers have with the "worst pain your can possibly imagine" concept is that they literally can't imagine worse because it's never happened to them. Everyone has a scale and everyone's scale probably goes to 10 where 10 is the worst thing that's ever happened to them. You can say "worse than dunking your feet in a hot deep fryer" and while I'm sure that would suck quite a bit, I can really only compare it to what's happened to me before. | [
"Here's something to read while you wait: ",
"http://en.wikipedia.org/wiki/Dolorimeter"
] | [
"Well that's a complicated question because there are so many different types of pain that can be measured at several levels.",
"Thermal pain signalling differs from pressure pain which differs from painful itch. Its not only that our brain interprets these signals differently, its that they arise from different ... | [
"This",
" might be of interest."
] |
[
"How does the streetlamp stave off winter dormancy for part of this tree? Pic included in text (x-post from mildyinteresting)"
] | [
false
] | [deleted] | [
"That branch is actually still dormant; those leaves aren't functioning, the chlorophyll has already drained out of them. ",
"My guess is that it has something to with the abscission layer in those leaves, where the plant weakens special cells to allow the leaves to fall. Formation of this layer is thought to be ... | [
"There is some uncertainty as to the purpose of leaves changing color in the Autumn. Most agree that the yellow/orange/red tones of pigments called carotenoids (think ",
") are simply what is remaining after the green chlorophyll is broken down. In turn, as these pigments degrade, the last color you see is brown,... | [
"There is some uncertainty as to the purpose of leaves changing color in the Autumn. Most agree that the yellow/orange/red tones of pigments called carotenoids (think ",
") are simply what is remaining after the green chlorophyll is broken down. In turn, as these pigments degrade, the last color you see is brown,... |
[
"Most animals seem to have an instinctive fighting style, what is ours?"
] | [
false
] | [deleted] | [
"Due to ",
"changes in Reddit's privacy policy",
", this comment has been overwritten by an open source script to protect this user's privacy. ",
"If you would like to do the same, add the browser extension ",
"GreaseMonkey",
" to Firefox and add ",
"this open source script",
". ",
"Then simply cl... | [
"\"We\", as in modern man, did not exist before our tools. Our tool use stretches back ",
"far further",
". Additionally it is thought that early tool use originated, from the H. Habilis smashing bones to extract the marrow as they scavenged the plains. Thus, it is possible our tool use also predated our huntin... | [
"When the prey animal is lying in front of exhausted, they likely threw stones or beat it with clubs before they developed spears. Tool use ",
" our instinctive fighting style."
] |
[
"Does a person's circadian rhythm still \"work\" if they never see the sun? Even if they don't have an alarm clock?"
] | [
false
] | [deleted] | [
"The definition of a circadian rhythm is that it is inherent to the organism, meaning that it \"works\" independent of environment. ",
"For organisms, such as plants, fungi, insects, and vertebrates, the means through which they have an inherent cyclic rhythm may vary (for the organisms listed, I believe each evo... | [
"Can it be assumed that our circadian rhythm is linked to the earth's rotation? Had humankind evolved on a planet which had days that lasted several earth days, would our circadian rhythm also be drastically different?"
] | [
"Yes, there is a central circadian clock - the suprachiasmatic nucleus, but every cell also has a circadian clock. This clock operates through expression of genes, including PER genes, which alter cellular activity. There's a continuous feedback between these proteins that are expressed and the system of gene expre... |
[
"What accounts for the difference in average human height between countries? i.e. Denmark, male avg = 6'0\", France = 5'9\""
] | [
false
] | I imagine there are many different factors; perhaps available nutrition, sunlight (do people, like plants, grow taller in an effort to get more sun?), culture, medicine, media influence, etc. Maybe elevation? | [
"Nutrition and genetics. "
] | [
"Right, but I doubt there are many French marrying the Germans or Germans marrying the Dutch. Countries tend to stay within their own population."
] | [
"The two tallest groups are Nordic and one of the tribes in Africa, I forgot which one. I think the Nordic is related to historical diet, while the African is related to heat dissipation and some other benefits.",
"An example of the role of nutrition is Japan, where over the past 100 or so years they have been g... |
[
"In nuclear pasta all the electrons merge with protons so what dictates nuclear pasta’s chemical properties? Please explain in simple terms because I am not an astrophysicist :)"
] | [
false
] | null | [
"Oh what a fun question!",
"So what you call 'chemical properties' I'm going to call 'material properties' since technically these aren't atoms, so there's no chemistry! Still, lots of your intuition from chemistry may hold. For example, what is the electrical conductivity of nuclear pasta? It depends on how elec... | [
"Um... What's... What's nuclear pasta?"
] | [
"Thank you very much! :)"
] |
[
"Statistically, what does it mean to go on a 'fishing expedition' with data?"
] | [
false
] | Is there a term for this? I believe it has something to do with having a large sample size, and measuring too many outcomes... Edit: I thought this was an easy one. I guess not... | [
"I have a nice example of this.",
"Take a look at ",
"this survey",
"\nAn insurance company collected data on 160,000 car accidents and then looked at how the star sign of the driver related to the risk of a crash. They found Geminis were the worst drivers, whilst Capricorns had the the lowest chance of causi... | [
"Not sure I can explain it statistically, just think of your odds fishing, then think of you odds of catching a fish that's never been caught. If you go on your fishing expedition and catch something everybody else has caught, whatever but suppose you found that fish everybody has been trying to land. I guess you c... | [
"The idiom \"",
"fishing expedition",
"\":",
"a search for information without knowledge of whether such information exists. (This involves asking questions with no preconceived notion of what the answers might reveal.) ",
"I.e. in general, looking for something without knowing what you're looking for. The ... |
[
"How can we know if higher dimensions exist?"
] | [
false
] | How can people possibly know that there are higher dimensions? Is there a sort of deductive process based on evident mathematical principles or is the general method more inductive, based on observations that seem to fit this idea? Furthermore, can the human mind even possibly comprehend a higher dimension? By higher dimension, I mean any dimension above 4, be it temporal, spacial, curled up, or otherwise altered. | [
"It's mathematical. Remember, a \"dimension\" is nothing more or less than a degree of freedom. The equations don't care if that degree of freedom is in position space or momentum space or in fact any abstract configuration space."
] | [
"Here",
" is an experiment that is testing whether extra dimensions modify the strength of gravity at very short scales. They've concluded that an extra dimension must be smaller than 44 microns in size."
] | [
"All equations."
] |
[
"Why/how are sulfonylureas, meglitinides and injectable insulin effective in the treatment of type 2 diabetes?"
] | [
false
] | In type 2 diabetes where the major problem is insulin resistance rather than an absolute inability of the pancreas to produce insulin as in type 1 diabetes, how do drugs such as sulfonylureas and meglitinides that act by simply increasing insulin secretion by pancreatic beta cells, and injectable insulin work in the treatment of T2DM? If the insulin is having a reduced effect because of the body's resistance to it, then how does simply increasing the levels of circulating insulin work? | [
"Sulfonylureas work to inhibit the opening of a certain potassium channel (the K_atp channel) which serves to depolarize the beta cell, releasing intracellular granules containing insulin. The depolarization opens voltage-gated Ca2+ channels which set the granule release process in motion. Meglitinides do the same,... | [
"The medicines don't work as well a person becomes more insulin resistant. ",
"As a person becomes glucose intolerant the person is started upon a biguanide like metformin which acts peripherally to reduce glucose levels (or inhibits hepatic glucose formation) or a slufonylurea that increases pancreatic insulin s... | [
"The idea behind a sulfonylurea is simple. You're right, the patient is insulin-resistant. But more insulin just gives a better response. ",
"I should also mention there is a shift from medications (like snfu's) which stimulate islet cells to other medications which dont cause the pancreas to effectively burn out... |
[
"Do rockets suffer from aerodynamic drag caused by truncated tail?"
] | [
false
] | I don't know the right terminology so please let me explain. In car and airplane aerodynamics, engineers have to consider not only aerodynamics on the front-facing side of the vehicle, but also on the back side. The idea is to reduce turbulence and low pressure, which has the effect of "pulling the vehicle back". I imagine this by having a moving object creating a vacuum (low pressure) behind itself, which "sucks in" everything around, including the object itself. Better shapes of the object will allow more air to fill out the vacuum (low pressure) area quicker, which will induce lower "pulling" force on the object. Now the question is, what about rockets? If you look on , it clearly shows how the rocket body is simply "cut off", or flat, and then the engine nozzles stick out. In my mind such moving body has to create lots of low-pressure-pulling force in the area between the flat rocket bottom and the tips of the nozzles, especially at high speeds. Now obviously it cannot be perfectly aerodynamic as we may need some nozzle gimballing, or have the incoming air cool the nozzles down a bit, or simply vibrations prevent us covering up the engines/nozzles. But such a flat surface simply looks like a beginner's first attempt at rocket design (no offence :) ). Or is that simply ignored due to short time spent in the dense part of the atmosphere? EDIT: Because there's some confusion, I made a to explain. I am specifically talking about the area between the flat and the end of the nozzle. The red arrows on the picture depict turbulent air. The other rocket design does not suffer from this as there is no such empty space. Just look at the Saturn V tail as I linked before, it has the first design from my picture. I hope it's clear now. Also bear in mind I understand it is not always possible to engineer the second design, I mentioned that above, but it should be possible to do something in-between those two. | [
"The implication of the first statement is that the hot gasses in the plume are exerting a force on the rocket. They aren't, or at least whatever force is applied is inconsequential.",
"But they are exerting a force on the rocket. Conservation of momentum doesn't happen by magic; you can't have an acceleration w... | [
"it's not the hot gasses in the plume pushing the rocket that makes it move. Rather it's the momentum of the hot gasses being ejected out the engines that causes the opposite momentum to be imparted to the rocket.",
"\"The hot gases push the rocket\" and \"the momentum of the hot gases being ejected causes the op... | [
"Two factors spring to mind.",
"Streamlined trailing edges are important to subsonic aerodynamics, but relatively unimportant in the supersonic regime. Check out the ",
"trailing edges of the X-15",
" There will be a shockwave originating at the corner of the trailing edge. Since aerodynamic disturbances cann... |
[
"Can we naturally exhaust our neurotransmitters?"
] | [
false
] | So as I know it serotonin and dopamine can be exhausted by certain drugs, and as a result we won't feel as good before they were all used up. The rate of the production also has something to do with this I believe. But say if we were to be naturally happy and social and being around someone we love (oxytocin?) all the time could we exhaust these stores and end up having a natural 'crash' where we don't feel as happy social or in love until these transmitters are restored? thanks in advance :) i'm very curious | [
"I can't really comment about the neuromodulators you mention, but there are other neurotransmitters that are used for the more basic excitatory/inhibitory communication between neurons such as glutamate and GABA. These transmitters can also deplete from synapses, or at least lower in their rate of release.",
"Fo... | [
"Some tremors are caused by a central issue in the brain, rather than a peripheral issue with the muscles, but in general that type of depletion is thought to be quite common.",
"There were some very early studies done of muscle psychology that showed that you can continue to directly electrically stimulate muscl... | [
"I've heard that similar mechanisms can explain fatigue in muscle tissue - that certain types of fatigues can occur where neurotransmitter depletion occurs before 'nutrient' (oxygen, glucose, etc) depletion occurs, causing muscle fiber activation to fail sooner than expected.",
"Do you know if such neurotransmitt... |
[
"Why do I constantly get painful (and audible) electric shocks, and how can I stop it?"
] | [
false
] | null | [
"We can't comment on personal anecdotes / isolated incidents without resorting to speculation which we try to avoid."
] | [
"OK. Can you suggest a sub to put this? I can't think of one that's quite right."
] | [
"You could try ",
"/r/findareddit",
" for help in finding an appropriate sub"
] |
[
"Do beverages get \"flat\" quicker when in a plastic bottle, in comparison to a glass bottle?"
] | [
false
] | My workmate has a theory that this is the case. Any facts, theory or science behind it? | [
"Yes, they do. Plastic (soda bottles are usually made of ",
"PETE",
", which is much more permeable to CO2 and oxygen than glass is. Similarly, this is why you're unlikely to find wine in plastic bottles/bags unless it's intended for relatively rapid sale and consumption."
] | [
"The CO2 and O2 will actually diffuse through the PET. It may be strange to think of diffusion happening in solids, but it does, just at a slower rate. Diffusion rates increase with increasing temperatures."
] | [
"/u/Dpgg94",
" this diffusion is also why bottled water tastes bad after sitting out in the sun. The plastic isn't leeching into the water, rather the oxygen is diffusing out of it. ",
"See here\n",
"https://www.reddit.com/r/askscience/comments/1sdgna/why_does_water_that_has_been_sitting_for_a_while/"
] |
[
"Can left-coiled snails only mate left-coiled snails? And do snails have a gender?"
] | [
false
] | I have seen this post in : is this biologically possible? | [
"All but a few species of land snails are simultaneous hermaphrodites, male and female at the same time.",
"The whole body is asymmetrical, including the reproductive opening (which is on one side), so if the body orientation is flipped, things don’t line up right."
] | [
"Most can inseminate themselves but they usually prefer to mate with partner if one is available."
] | [
"The first part of your question has been well answered by others. The second part depends on what you mean by gender. In biology, we generally talk about animals' sex, based on their biology, which in most cases is either male or female.",
"In simultaneous hermaphrodites, individuals are both sexes at once. So t... |
[
"What is the speed of gravity?"
] | [
false
] | Annihilate a hunk of matter with an appropriate hunk of antimatter, leaving behind only energy. If you're paying attention, you will see the flash before you hear the explosion, assuming that you are performing this test in an atmosphere. (You're crazy if you are.) If you were carefuly monitoring the explosion with a device sensitive to discern the presence or non-presence of the gravitational pull of the mass of matter, would you notice the change in gravitational force before or after you saw the annihilation? Do gravity waves travel faster or slower than light? | [
"Some previous threads about this:",
"1",
"2",
"3",
"4"
] | [
"c"
] | [
"Thank you!"
] |
[
"Is it infinitely improbable to hit any random point on a sheet of paper?"
] | [
false
] | A sheet of paper has infinitely many points on it. When I take a needle, close my eyes and strike the paper at random, the probability of me hitting any random point is one in an infinite. What's wrong with this speculation? | [
"If a point is defined as being infinitely small, then your needle hits an infinite number of points when it touches the paper (since the tip of a needle is not infinitely small).",
"The main flaw in your reasoning is that you're trying to translate mathematical models into the real world, where things work sligh... | [
"You do have the issue of how big the paper and needle you are using with those parameters. Your paper could be infinitely small or big, as could your needle.",
"The moment you set a scale to it, you start dealing with real numbers and infinity cant really be used to describe it"
] | [
"The probability of hitting a specific point is infinitely small (it may or may not be a zero depending on if we care about all that plank length malarkey). The probability of hitting any one of them is 1.",
"It's like the lottery. The probability that you (or a particular person) will win it is very small. The p... |
[
"Can a sane mind be turned schizophrenic?"
] | [
false
] | null | [
"Yes. About 1 in every 100 people. Kinda changes the way you view the world and the 'common person' you run into. "
] | [
"But, just because you have the gene, doesn't mean you're schizophrenic. You need to the code (1%), and you need the trigger. Which, the trigger is different for everyone because it depends on how you personally deal with situations and perception. In most cases, it's triggered by traumatic stress or head trauma. I... | [
"Follow up (more of a definition question): what is the state of mind called where you've truly convinced someone they're insane?"
] |
[
"Do all salts taste salty or just NaCl?"
] | [
false
] | null | [
"I'm sorry that people are downvoting you. I think people think you're trolling, but I had this very question back in the day, before I took chemistry. ",
"When you think of salt, you're thinking of table salt. Its chemical formula is NaCl -- one part sodium (Na), one part chlorine (Cl). ",
"In reality, there a... | [
"Saltiness is a taste produced primarily by the presence of sodium ions. Other ions of the alkali metals group also taste salty, but the further from sodium the less salty the sensation is. The size of lithium and potassium ions most closely resemble those of sodium and thus the saltiness is most similar.",
"Basi... | [
"How can it be salt and not salty?"
] |
[
"Why do we always hear about early explorers spreading diseases to natives and never the other way around?"
] | [
false
] | null | [
"Repeat question"
] | [
"Sure thing. I want to know why the early explorers who have been blamed for spreading diseases to the natives of countries they have visited, don't (or from what I've heard) pick up diseases from the natives themselves. ",
"Surely if both groups have been as isolated from each other then they must be as suscepti... | [
"These past questions may be able to help you:",
"http://www.reddit.com/r/askscience/search?q=disease+native&restrict_sr=on&sort=relevance&t=all",
"TL;DR version - population density and domestication of animals meaning the immune systems had different susceptibility to species-jumping diseases. "
] |
[
"Would a match be able to burn itself out in zero gravity?"
] | [
false
] | So if you lit a match in zero gravity, would it be able to burn itself out? Normally heat rises to move the carbon dioxide out of the way, but in zero gravity it would just form a bubble around the flame. Would there enough oxygen able to get in or would it just choke itself? What about a lighter, which is slightly different? Would it be able to sustain a flame in zero gravity? | [
"Sure, but the distribution of burning gas looks different (closer to a sphere). ",
"Here's",
" a video."
] | [
"Here's what Google turned up.",
"http://www.youtube.com/watch?v=fuFftT6ZR4k&feature=youtube_gdata_player"
] | [
"Yup, they have KClO3 in them thus the reaction can take place without oxygen."
] |
[
"Can something be waterpoof but not some other liquid proof?"
] | [
false
] | [deleted] | [
"Yes. Thin sheets of ",
"PDMS",
" are waterproof, but will let multiple organic solvent leech through.",
"In this case, it is really about the polymer being oily/hydrophobic/non-polar. So the water will not go through easily since it is such a strong polar molecule. But a non-polar solvent will find its way t... | [
"Sure, easily. Nitrile gloves are waterproof and resistant to some common chemicals, but they're also permeable to a lot of solvents. Acetone is a very common organic solvent, and nitrile is at least semipermeable to acetone."
] | [
"Yes, certainly. In one famous example, the highly toxic liquid ",
"dimethylmercury",
" can easily penetrate waterproof latex gloves, going right through them in seconds. ",
"This example was discovered when a scientist named ",
"Karen Wetterhahn",
" accidentally spilled a few drops of the liquid onto her... |
[
"What exactly happens when you delete data from a computer? Where does the deleted data go? Is their residue from the deletion?"
] | [
false
] | null | [
"There are two parts to a file system: an index of the data, and the data itself. When you delete a file, you are removing the entry from the index, but the file stays right where it is until the space is needed for another file.",
"When you change a file (or the index itself), it overwrites the applicable portio... | [
"When you empty your trash can, the system doesn't delete the data; instead, it just tells your hard drive that the data no longer exists, although it is still technically on your hard drive, allowing the system to overwrite those segments that previously contained the data.",
"With the proper equipment, one can ... | [
"Answering the question from a physical perspective...",
"\"Data\" isn't usually a physical substance. It is the interpretation of the state of an object. For different media (hard disks, flash drives, computer RAM) the state is stored in different ways.",
"For spinning platter hard disks, when we change (or de... |
[
"How are the aluminum compounds in antiperspirants effective in blocking sweat production? What is unique about their acid/base properties that help them do this?"
] | [
false
] | - Aluminum chloride - Aluminum chlorohydrate - Aluminum hydroxybromide | [
"Aluminum salts form all kinds of gel-like hydrated precipitates in water -- the exact chemical composition depends on pH. In antiperspirants, the aluminum salts interact with moisture coming out of your sweat glands and create precipitates that block the ducts of those glands, preventing sweating. "
] | [
"For very likely similar reasons, aluminum salts have notable antimicrobial properties and are pretty effective at killing any bacteria in the \"clogged\" areas.",
"Non-aluminum antiperspirants often have to add in another antimicrobial (triclosan, polyhexamethylene, etc.) as a substitute for exactly the reason y... | [
"Why doesn't this cause a ton of pimples? It was my understanding that pimples and zits come from blocked sweat ducts in the skin."
] |
[
"Bacteriophage Reprogramming"
] | [
false
] | [deleted] | [
"Are you talking about ",
"phage therapy",
"?"
] | [
"Possibly however this would increase the complexity of the phage far beyond its physical potential.\nPhage potential complexity can be measured by their size, and usually only come to about 50,000 base pairs, (Lambda phage only have about 48,000).\nFor more information on synthetic organisms the work of Craig Vent... | [
"Even if you could, there's no guarantee that an infected harmful bacterial cell would be any better for your body. For example, strep throat is caused by a viral infection. But the viral infection is of bacteria that live in your throat. These dying bacterial cells produce toxins that agitate the human tissue.",
... |
[
"What are the chances meteorites hit satellites and space stations?"
] | [
false
] | Or on mars, with no atmosphere what are the odds a meteorite will hit the rover and destroy it? Is this risk something they consider? Or is it too rare to care about? Regarding satellites and space stations, surely taking damage from them isn't that rare! | [
"Let's look at the math. The surface of a sphere with the same radius the orbit of a satelite (I assume about r=7000km) is 4",
"r",
" so 6.15e8 km",
" = 6.15e14m",
" Assuming 10.000 satelites in orbit and one having a cross section of about 10m",
" we end up at an overall sattelite cross section of 100.00... | [
"A good start, next you need the frequency with which meteorites cross that orbital distance. Also, there exist asymmetries in meteorite frequency based on latitude and longitude. Micrometeorites HAVE hit satellites in the past and it is more common than you might think: ",
"http://blogs.smithsonianmag.com/smartn... | [
"This maths is beyond me, but does this also assume that the meteorite will hit the orbital sphere directly? If it's at an acute angle it will have a greater chance of hitting something"
] |
[
"Why does a circular paper airplane fly so well?"
] | [
false
] | I have been searching for this for a while. A circular winged airplane (like ) works exceedingly well--fold one and throw it like a football if you don't believe me. Yet, i have no explanation for why it works so well. In principle, a circular wing should provide no net force in any direction, yet it clearly has a lift force. My other theory was that air funneled through the center should have a higher velocity and provide a lift force, but the plane stays aloft even without a positive pitch (I would also expect this to create a great deal of drag). So I pose to you, AskScience, why does a circular paper airplane fly so well? | [
"I think if a reddit search doesn't find it, it's fair game. Otherwise, reddit might as well abandon its own search and simply link to google."
] | [
"No offense, but you mind giving us a hint on what you searched for to get to that thread via the search function? The title of that thread if \"Can someone please explain to me why this works so well?\" which is very vague. It doesn't mention the word \"circular\" or \"fly\" and it doesn't mention the word \"paper... | [
"Ok, I think I've got a reasonably plausible explanation. There are 2 important things in the design of a paper plane: Pitch Stability and Zero Lift Moment.",
"Pitch Stability first. A paper plane is basically a flat plate and flat plate aerofoils suffer from pretty horrendous pitching moments. To remain stable, ... |
[
"How did scientists figure out how many electrons/protons/neutrons are in each element?"
] | [
false
] | I've often wondered how scientists have figured out how each element is composed. You can't see electrons as far as I know, so how do you go about measuring them? Weight? Charge before and after? Some other method?? The reason I ask is because I have always taken the atomic theory at face value, and while I don't doubt it's veracity, I am puzzled as to how we came about it in the first place. Thanks guys! | [
"The charge of an electron was figured out by ",
"Milliken's oil drop experiment",
" (even though it was still slightly off - but amazing nonetheless). In short, he sprayed droplets of oil in an electric field and measured how fast they dropped. From there he can calculate how much charge was contained in the d... | [
"Chemistry has a fascinating history of scientists figuring out pretty complex natural puzzles with very scant information.",
"Early chemists mostly used weight to determine the results of reactions. From this, they observed that quantities reacted in simple ratios -- for example, Hydrogen+Oxygen -> Water always ... | [
"I'd say so! An error of 1% is damn impressive. I knew the oil drop experiment was precise, never realized he practically nailed the bulls eye. "
] |
[
"AskScience: What would the universe be like if the if the speed of light was 1 m/s?"
] | [
false
] | I know there would be a major delay in seeing objects, but what else would this change? Also, would everything appear brighter since light would be "more compact"? Instead of m/s (since pjfoster and xnihil0zer0 pointed out a meter is defined by the speed of light) how about we pretend we use a unit that would remain the same regardless of the speed of light. How about 1 yard/second. Just a clarification, I am saying that c=1 yard/second | [
"Special Relativity Simulator",
" on Youtube. It is a simulation of what you would see if the speed of light were 1 m/s."
] | [
"Further question to this--when you talk about being able to run a letter faster than the information down a wire--wouldn't the \"new\" speed of light still be the \"universal speed limit\"? As in, wouldn't it still be the fastest thing in the universe?"
] | [
"Further question to this--when you talk about being able to run a letter faster than the information down a wire--wouldn't the \"new\" speed of light still be the \"universal speed limit\"? As in, wouldn't it still be the fastest thing in the universe?"
] |
[
"What are actin and myosin made of?"
] | [
false
] | I was curious after reading this article from what exact amino acids are actin and Myocin made of? If there are a lot of amino acids involved, are there specific amino acids I could take that are used to convert into the needed actin sequence? For example taking glutamate supplements would be good for repairing muscle tissue because it can be converted into (let's say) glycine? Original article here! THX! | [
"Here is the sequence for the human beta actin protein:",
"MDDDIAALVVDNGSGMCKAGFAGDDAPRAVFPSIVGRPRHQGVMVGMGQKD\nSYVGDEAQSKRGILTLKYPIEHGIVTNWDDMEKIWHHTFYNELRVAPEEHPVLL\nTEAPLNPKANREKMTQIMFETFNTPAMYVAIQAVLSLYASGRTTGIVMDSGDGV\nTHTVPIYEGYALPHAILRLDLAGRDLTDYLMKILTERGYSFTTTAEREIVRDIKEKL\nCYVALDFEQEMATAASSSSLEKSYELPDGQV... | [
"Since your question seems to revolve around the effect of amino acid supplementation on muscle tissue repair or muscle building, I will address that question, as opposed to just giving you the sequences for the proteins or mRNA etc...which are not particularly useful in answering your question.",
"Here is the sh... | [
"Muscles are composed of more than just those two proteins. so loading up on the amino acids for actin and myosin would be as effective as loading up on beta-carotene for the end purpose of improving your eyesight. It will help you maintain and grow but it's not going to supercharge your body."
] |
[
"When the \"temperature\" of the CMB is described as being 2.7K, is this describing the blackbody spectra or some other statistical mechanics way of measuring temperature?"
] | [
false
] | I've found contradictory information on this point when trying to research it before. I'd always assumed that 2.7K referred to the apparent blackbody radiation spectra of the big bang afterglow, but redshifted due to the expansion of space. However, I read a comment on another thread a while ago that made the claim that 2.7K was some statistical mechanical measure of the temperature of the resulting . I never did take a statmech class, so I'm a bit clueless on that part of it. Are the two even related? Which does the 2.7K figure relate to? | [
"Blackbody."
] | [
"Those two are the same thing. Same distribution, same physical idea. Photons are emitted from a perfect absorber (so that the emission spectrum is independent of any incident spectrum), and the emitted photons are in thermal equilibrium with that absorber.",
"Another way to think of them being the same is that a... | [
"It fits the black body radiation very well. "
] |
[
"How does gravity affect fire? Theoretically if we were to artificially increase or decrease gravity would it affect a flame?"
] | [
false
] | null | [
" The higher the gravity, the more 'teardrop' shaped a flame will be, and the less gravity, the more spherical.",
" To answer your question with a picture, check this out - ",
"the candle on the left is on earth, but the one on right is in space.",
" Since there isn't a preferred direction (on earth is given ... | [
"I went to youtube and searched \"space fire\".",
"Here is the video of the picture you linked. ",
"New Form of Fire Seen Aboard the Space Station",
"And here is another video result: ",
"Fire In Space - It's Not What You Know\n",
"And here is an article from space.com which pretty much says everything OP... | [
"right when you hit the bottom you'll experience a strong decelerating force, and the salad dressing will settle very suddenly - faster than it otherwise would if you were just standing around",
"I'm a bit short on roller coasters at the moment. Couldn't you reproduce just this by swinging the bottle around on t... |
[
"Why do cleaning/washing products only claim to kill 99.9% of germs?"
] | [
false
] | Why can they not claim to kill 100%? Are there some bacteria that are resistant to these products or is it just for legal reasons? | [
"This is actually a statistics issue, not a legal issue. In order to make the claim that something is a disinfectant (i.e., it actually kills germs), you have to run tests and gather data. Numerical data is always reported in terms of confidence intervals and significance, which means you always have some variabili... | [
"In the same line, it's also too expensive to prove that you killed 100% of them. "
] | [
"http://www.reddit.com/r/askscience/comments/n29fi/when_a_soap_says_it_will_kill_999_of_germs_what/",
"\n",
"http://www.reddit.com/r/askscience/comments/mtoqi/what_is_the_01_of_germs_that_my_soap_cant_kill/",
"\n",
"http://www.reddit.com/r/askscience/comments/kyhr1/kills_999_of_germs_so_why_hasnt_the_surviv... |
[
"How is a Honey Bee's sting evolutionarily advantageous if it dies after using it?"
] | [
false
] | null | [
"It's less about the survival of the individual honeybee and more about the survival of the colony. If a small number of bees attack an intruder and fend that intruder off, then the colony survives even though a small number of individuals died defending it. There's really no selective pressure to produce more robu... | [
"Because only the queen and the drones reproduce. The death of the worker does not reduce the reproductive success of the bees that reproduce. In fact the death of the drone can prolong the life of the reproducing bees in the hive, and hence their reproductive success, by discouraging attacks on the hive. "
] | [
"I think for yourself you may find the wikipedia entry on ",
"eusociality",
" interesting. \"Eusocial animals have appeared paradoxical to many theorists of the field of evolution, including W. D. Hamilton: if adaptive evolution unfolds by differential survival of individuals, how can individuals incapable of p... |
[
"What causes a blister to hurt soo much when popped?"
] | [
false
] | When I compare it to a cut that goes much deeper than a blister, the cut doesn't have much pain compared to it. What causes it pain and why does it get easily infected? | [
"Please read what I wrote, I see you have just skimmed it. \n\"When I compare it to a cut that goes much deeper than a blister\""
] | [
"This answer still applies. Do a quick calculation of surface area of the cut vs a blister. ",
"For a cut, the surface area can be something like 1 inch long X .25 inches deep X 2 because the cut has two sides= .5 square inches. ",
"For a blister, its surface area could have a radius of .5 inches, so its area w... | [
"Ok, I guess it's not 100X bigger, but a cut still has less surface area and nerve density"
] |
[
"Why can't we rotate antibiotics?"
] | [
false
] | null | [
"Hi inkoDe 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 followin... | [
"You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the following flair categories and contain no other text:",
"'Computing', 'Economics', 'Human Body', 'Engineering', 'Planetary Sci.', 'Archaeology', 'Neuroscience', 'Biology', 'Chemistry', 'Medicine', ... | [
"You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the following flair categories and contain no other text:",
"'Computing', 'Economics', 'Human Body', 'Engineering', 'Planetary Sci.', 'Archaeology', 'Neuroscience', 'Biology', 'Chemistry', 'Medicine', ... |
[
"Why do bubbles in my water bottle stick to the sides?"
] | [
false
] | I was waiting to enter my calc 3 lecture one day and started to wonder why all the bubbles in my water bottle did not just float to the top. - sorry for the poor picture, this is my water bottle I know that water can have gases dissolved and as the water warms these gases for bubbles but why do they stay there? I knew from the fluids chapter in my physics class that the pressure below the bubble, so it should rise. The fact that they don't led me to two possibilities: Are either of these correct? Why does the bubble not move? | [
"The surface tension of water is a high energy state, so to create surface area on water, it requires energy. Having part of the bubble's surface made up by the inside of the bottle requires less energy than the whole bubble being surrounded by water, so it stays because that is the lowest energy / entropy state."
... | [
"The bubble is, at that point, in a state of force balance. There is a buoyant force created by the pressure difference you mention, however, there are drag forces of the bubble against the water, and against the wall which balance it (shear).",
"In static situations this force is dominant. When even small flow... | [
"Great explanation, thank you! "
] |
[
"Is there a difference in reading comprehension when reading an ebook vs. traditional print?"
] | [
false
] | null | [
"It was an interesting read, but it feels a lot like an op-ed piece that is on a mission to prove the writer's bias as being correct rather than just letting facts tell the story.",
"It goes on - at great length - to point out that reading a book is generally more efficient than reading on a LCD or CRT screen - u... | [
"It was an interesting read, but it feels a lot like an op-ed piece that is on a mission to prove the writer's bias as being correct rather than just letting facts tell the story.",
"It goes on - at great length - to point out that reading a book is generally more efficient than reading on a LCD or CRT screen - u... | [
"I simply don't remember as much from a book that was read on a device that can easily browse Reddit, check work emails or play Angry Birds in an instant. ",
"How do you play Angry Birds on a e-ink device?"
] |
[
"Is watching TV in the dark bad for your eyes?"
] | [
false
] | [deleted] | [
"I like have a TV light on. It's a very low watt lamp behind the TV that casts a little light onto the wall. It makes for less contrast between the bright light from the TV and the otherwise dark room.",
"Also: ",
"http://www.sciencedaily.com/releases/2006/04/060425015643.htm"
] | [
"So is it bad to watch movies in theaters as well?"
] | [
"I'd like an answer to that too, but reading the article quoted above...",
"visual discomfort is caused by the ",
" in luminance between the television screen and the room’s dark background",
"Since the screen in a theater is so large itself (guessing it covers more than 3/4th of my visual space - in comparis... |
[
"How does the perception of spice scale?"
] | [
false
] | With the YouTube show , the host and guest eat increasingly spicier wings as the interview goes on. Why does it seem that the 100k-300k Scoville range hits much harder than the 1m-2m Scoville range? | [
"The flagship chemical in hot peppers is called Capsaicin, which basically works by tricking your brain into thinking your mouth is on fire.",
"No, seriously.",
"your tongue and mouth are covered with a chemical receptor called the Transient Receptor Cation Channel V1 abbreviated as TRPV1. The purpose of this o... | [
"This may not completely answer your question, but one thing to point out is that Scoville was originally based on how far you could dilute a spicy food and still detect it. For example, 100 Scoville meant that you could detect it in a 100:1 dilution, while 100,000 meant you could detect it when diluted by a 100,00... | [
"Do you know of any desensitization curves for TRPV1? Where is the point of diminishing return for higher Scoville?"
] |
[
"In Carbon Dating, why hasn't all the Carbon-14 decayed over the millenia?"
] | [
false
] | I understand how carbon dating works, but I'm wondering how there are any carbon-14 to test when it has a half life of 5700 years. Wouldn't it have all decayed over millions of years? | [
"This is covered pretty well in ",
"http://en.wikipedia.org/wiki/Carbon-14",
". Basically carbon-14 is produced in the upper atmosphere and absorbed by living creatures (by respiration). When the creature dies, it no longer absorbs carbon-14, so you can use that for a while to date when it died."
] | [
"Carbon-14 dating doesn't work to date objects from millions of years ago, as you have rightly concluded. You can use it back to around ",
"50,000 to 100,000 years",
".",
"There are other decay processes that can be used for earlier times. You can read about some of them ",
"here",
" and ",
"here",
... | [
"I think the OP is more concerned with where any 'new' C14 comes from."
] |
[
"How small and detailed could we make a Fresnel lens?"
] | [
false
] | Seeing them in the wild, you either look at it from a distance or they're quite grainy, I know they're cheap. So, probably the image might look slightly like the way insect-vision is portrayed in movies, segmented like, but if we can make the tiny tiny little mirrors and sensors in DLP projectors and smartphone camera sensors, (I don't know if the features are smaller on phone cams or pro 16k cams or what) is there any way, expensive and convoluted it may be, to manufacture a super small scale fresnel lens that would provide a clear picture. I understand this would likely never be profitable in a smartphone or anything but I just love the idea of a telescope that's much wider than it is long, or a pair of binoculars that's scarcely thicker than some thick glasses. In case you can't tell I don't know how optics work.. I flaired it for Engineers because I suppose that's closest? Rather than physics? I also just imagined a microtelescope could be made using a DLP mirror module as the collecting mirror with a little sensor in front of it, the uses however, escape me, aside from proof of concept or just messing about. | [
"In an ordinary Fresnel lens, the step changes in thickness are not especially damaging to their performance; you can mostly ignore them. But as the steps get closer together, they start to really matter. You end up in a regime where the device would be considered a diffractive optical element (DOE).",
"The steps... | [
"The main advantage of the Fresnel lens is that the lens itself is much thinner and lighter than an equivalent normal lens. But small lenses are already lightweight so there is very little to gain from switching to a Fresnel lens.",
"A Fresnel lens does not automatically make the whole optical system shorter. A c... | [
"As your gradations approach the wavelength of the light you're dealing with, your efficiency falls off a cliff. I'd guess 10-100x wavelength is the theoretical lower limit? It's not going to really make a clear picture for the camera though, these lenses are mostly used to focus the flash."
] |
[
"How do power plants, on a national grid level, figure how much electricity to generate?"
] | [
false
] | The amount is dynamic based on consumption. I may or may not turn on the AC for instance. How do the plants ramp up or ramp down production that is so closely tied to consumption in real time? | [
"One of the parameters that can keep the energy net in check is the kinetic energy of the generators. When more energy is being used than there's been produced, the generators will start spinning slower, feeding their lost kinetic energy into the net. This wikipedia page has some nice information: ",
"https://en... | [
"Well, among other things, they can try to predict peaks and valleys in the usage, and lower production in times of the day or year where people would be too hot for a heater and too cold for an AC. They make that prediction based on past usage, demographic changes, temperature variations, even data on unemployment... | [
"Think of it this way. At any given time there could be any number of drivers using a certain road. Yet oddly there generally is a consistent flow of traffic. Adjust it for the time of day you could make a pretty good guess at the rate of cars. ",
"It's the same with power. You might think what if everyone plugs ... |
[
"[Physics] If the universe is expanding, that must mean that space is being created. If space is being created, then is time also being created? If so, what does that even mean exactly?"
] | [
false
] | null | [
"that must mean that space is being created.",
"Why must it mean that?",
"If space is being created, then is time also being created?",
"I'm not sure of the link you are trying to establish here. Whether or not the future and past really exist is a philosophical question."
] | [
"Space can't exist without time right? If the universe is expanding, that means space is being created, right? And if space is being created, wouldn't that mean that time is being created?"
] | [
"Within the current paradigm of physics these are not well posed statements or questions. ",
"Space can't exist without time right? ",
"In the same sense that left \"can't exist\" without up, i.e. they happen to both exist but there is no reason they had to.",
"If the universe is expanding, that means space i... |
[
"How do we still have radioactive particles on earth despite the short length of their half lives and the relatively long time they have been on earth?"
] | [
false
] | For example carbon 14 has a half life of 5,730 years, that means that since the earth was created, there have been about 69,800 half lives. Surely that is enough to ensure pretty much negligable amounts of carbon on earth. According to wikipedia, 1-1.5 per 10 cabon atoms are carbon 13 or 14. So if this is the case for something with a half life as long as carbon 14, then how the hell are their still radioactive elements/isotopes on earth with lower half lives? How do we still pick up trace, but still appreciable, amounts of radioactive elements/isotopes on earth? Is it correct to assume that no new radioactive particles are being produced on/in earth? and that they have all been produced in space/stars? Or are these trace amount replenished naturally on earth somehow? I recognize that the math checks out, and that we should still be picking up at least some traces of them. But if you were to look at it from the perspective of a individual Cesium or Phosphorus-32 atoms it seems so unlikely that they just happen to survive so many potential opportunities to just decay and get entirely wiped out on earth. I get that radioactive decay is asymptotic, and that theoretically there should always be SOME of these molecules left, but in the real world this seems improbable. Are there other factors I'm missing? | [
"Yes, carbon-14 is constantly being produced on Earth, for example by nuclear reactions in the atmosphere caused by cosmic rays."
] | [
"Radioactive materials with short half-life are produced naturally on earth through:",
"Radionuclides which have a short half-life and are not found in decay chains of longer-lived isotopes are, indeed, not found naturally on earth, except in tiny trace amounts; for example, pretty much any isotope of Technetium"... | [
"Which is why it's useful for dating. C14 (in CO2) is produced in the atmosphere, then captured by plants and turned into larger carbon molecules, which then potentially get eaten. Once the carbon is out of the atmosphere, no new C14 is produced and it'll eventually all decay, so you can measure how long ago the ca... |
[
"Does the mass of an object affect the intensity of the sonic boom that it creates when traveling at mach speeds?"
] | [
false
] | I am a tour guide at a museum in New York City with several prominent supersonic planes. Several days ago two of my fellow tour guides got into an argument about the effect an objects mass has on the intensity of the sonic boom that it creates. One believed that two objects with the same external shape would create different sounds as they passed the sound barrier if their mass was different, and the other believed that they would make the same sound. So, if there were two Concordes flying at the same mach speed, say 1.5 times the speed of sound, one loaded with passengers and cargo, the other empty, would the heavier Concorde make a louder "boom?" Also, there was some confusion in the debate between mass and weight, these two concepts are different, but does it make a difference in this context? | [
"The only factors that matter for the creation of shock waves in atmospheric flight are outer geometric profile (size, shape), orientation of that geometry relative to the free stream, airspeed, and air temperature."
] | [
"Yes, I agree. Mass (or density) of object does not matter. What only matters is the outer geometry of an object. ",
"In OP's example - two identical Concorde planes, only differing in total mass, the sonic boom will be the same in both cases."
] | [
"Gross wieght definatly has an effect on the shock wave as seen in this paper published by NASA ",
"http://www.nasa.gov/centers/dryden/pdf/88387main_H-2068.pdf",
" "
] |
[
"If an electric motor is supplied power but restricted in turning (like holding back a ceiling fan) what is happening which would cause it to 'burn up'?"
] | [
false
] | null | [
"When a motor is turning, that rotation generates a voltage, a 'back EMF', that acts against the flow of current. It is this voltage, not the resistance of the coils, that restricts the amount of power the motor draws. And as this is an impedance, it doesn't generate heat. The power - the current in the motor pushi... | [
"An impedance it's just a complex resistance so it's false to say it doesn't make heat, it can and in a motor it does. But the back emf limits the current and hence power and hence heat. As speed slows back emf drops, impedance drops, current rises, power rises, heat rises.",
"You don't have to stop a motor to lo... | [
"I second this post. Over my years of attending scrapheap challenges at the university where we make robots out of printers, this story is not only consistent with the theory but also with the practice. Motors that can't turn can draw much larger currents than when they do. The explanation offered here is also in h... |
[
"How do scientists know what specific genes to put/insert in GMOs?"
] | [
false
] | Since there are a lot of genetically modified organisms, how do scientists know what type of gene or what specific gene to put/insert in GMOs to obtain the best produce? | [
"You have to work backwards from what the desired phenotype is, what protein(s) are responsible for that phenotype, what genes are responsible for creating those proteins. ",
"Mapping the genome of many organisms has been a goal for many years after we conquered sequencing."
] | [
"By observing the gene's effects in its native organism? Geneticists aren't making genes from scratch. At most they are modifying what nature has already created, and then introducing them into their organism of interest. Then they would still observe their modified organisms throughout their lifespan to ensure it ... | [
"A lot of times GMOs are just crossbred plants that exhibit exceptional toughness, high yield, resistance to parasites, etc. Basically if this plant grows up to better than other plants through one way or another it will be used to crossbreed. ",
"For instance if this berry bush has higher than average fruit yiel... |
[
"Is the longest Neuron in the human body visible to the naked eye?"
] | [
false
] | The longest neuron in the human body, according to my AP Biology class, is 1 meter long and runs down the leg(s). Would it be possible to see it without any aid, or is it still too small to be seen? Would someone be able to feel it if it was draped across their hand? | [
"You’re thinking of neurons of the sciatic nerve, which runs from your toes to your spinal column. The nerve itself is visible to the naked eye as it is quite large. At mid thigh the nerve contains approximately 27,000 axons. However, a single axon (while the size may vary) is approximately 1-20um in diameter, simp... | [
"The giant squid axon is the structure we have used as a basis to study computational neuroscience as we could attach probes to it. "
] | [
"There are some very famous electrophysiology studies done on the giant squid axon by Hodgkin and Huxley (amongst others). "
] |
[
"Do the tidal forces of the moon affect clouds?"
] | [
false
] | Do the tidal forces of the moon affect clouds, or any other types of fluid bodies on earth? If so, how come the ocean’s tides are the only effect we (humans) are generally aware of or concerned about? | [
"There are \"atmospheric tides\", and they cause atmospheric pressure to vary very slightly over the course of the day. The height of the atmospheric tide is about a meter, meaning the pressure change is similar to what you'd experience climbing a 1-meter-tall hill. Totally not noticeable. That's actually simila... | [
"Note that these are gravitational atmospheric tides. There are also thermal atmospheric tides (still a tide!), which are typically just called atmospheric tides. They come about as a result of heat from the sun expanding the atmosphere and hence changing the distribution of mass of the atmosphere. The thermal tide... | [
"The Moon has gravity--just like Earth, but it's weaker (because it has less mass and it's farther away). The Moon's gravity affects every single thing on Earth--even the planet, itself. We really notice the tides, because they can be easily measured (unlike, say, clouds), because they can be obviously seen with ... |
[
"It's blazing hot in your room. You open the window and put a fan in it. Do you blow the hot air out? Or blow the cold air in?"
] | [
false
] | null | [
"Mine Ventilation Student- Personally, I would say bring the cold air in, it cools you down faster and more directly. If you were to implement an exhausting system it would be best to open another window to ensure steady state air movement."
] | [
"Summary of top five voted answers so far:",
"All agree to open a second window."
] | [
"you want the fan to be directly against your window. not just somewhere in the middle, and you want it blowing into your room. ",
"like this horrific drawing illustrates"
] |
[
"In alternating current (AC) devices, does the same electrons do all the work as they are just getting pushed back and forth?"
] | [
false
] | null | [
"TL;DR (Sure, sorta. But it doesn't really matter.)",
"The answer to this question can be a bit complicated. I will do my best to cover the major points from a relatively broad scope and hopefully someone else can help elaborate if necessary.",
"In AC circuits it is quite conceivable to have a zero net change i... | [
"When you get right down to it the electrons aren't small balls moving through an even fluid, but wavefunctions in a highly disordered semi-crystalline grid. What you're saying will be true on average, but the picture for an individual electron is horribly complicated."
] | [
"I'm a soon to be EE, (51 more days!) but I know nothing about AC, they just don't teach that at my school! I just figured that if for example, the input signal is sin wave then at intervals of 2*PI is the same electron in pretty much the same spot, it was just pushed forward and backwards again. ",
"EDIT: Thanks... |
[
"Does the human brain consume more energy depending on what kind of task someone is performing? Such as digging a hole, playing chess, reading a research paper, daydreaming etc."
] | [
false
] | null | [
"Not really. The brain's metabolic requirements are very stable across time, regardless of activity. The notion of \"thinking hard\" is somewhat misleading in this respect. Although the distribution of energy consumption across the brain does vary based on the cognitive tasks in which people are engaged (making tec... | [
"Different mental activities can affect the energy consumption outside the brain. Performing demanding mental activities than one does not specially like causes stress and stress increases metabolism (sweating, faster heartbeat, tensions in the body). ",
"https://www.scientificamerican.com/article.cfm?id=thinkin... | [
"Good overview!"
] |
[
"Metacognition in animals: where does science stand on that?"
] | [
false
] | [deleted] | [
"There is some of this work being done at a lab in Columbia University, looking at metacognition in monkeys. They have several studies that claim to have evidence that monkeys possess metacognition. I've actually attended a few of the talks given by these people.",
"I don't know if I fully agree that this is defi... | [
"What is metacognition?"
] | [
"A few studies have suggested that bees may possess some degree of metacognition, ",
"example",
".\nI'm not an expert though, so maybe this is full of baloney."
] |
[
"Liquid water is above the melting point of ice. If I put boiling water in a bowl made of ice the sides melt. If I put boiling rock in a bowl made of rock (crater or caldera) why don't the sides melt?"
] | [
false
] | null | [
"They do, just not as drastically as the ice. There are a few reasons for this. ",
"It takes a lot more heat to turn solid rock into liquid rock than it takes to turn solid water into liquid water. The temperature difference between solid water and liquid water is a lot smaller than the temperature difference bet... | [
"One nitpicky thing...when you see lava bubbling in a lava lake its not truly boiling. That's escaping gas bubbles percolating out...its more correctly effervescing like a giant bowl of face melting Dr Pepper. Pure quartz, for reference, boils at 2230 C (4050 F). Hottest lavas erupt right around 1200 C.",
"But an... | [
"It takes a lot more heat to turn solid rock into liquid rock than it takes to turn solid water into liquid water. The temperature difference between solid water and liquid water is a lot smaller than the temperature difference between solid rock and liquid rock. Assuming things are happening in a room at room temp... |
[
"What is the lethality of Drosophila Tra gene loss?"
] | [
false
] | null | [
"If ",
"this",
" is the gene that you're interested in, it seems that a loss of function for this gene may cause sterility and courtship behavioral defects, but the flies are still viable. (See the \"Summary of Allele Phenotypes\" tab)",
"EDIT: ",
"This",
" page details the specific alleles (some with los... | [
"Wow, I honestly did not think I would get any sort of response, and certainly didn't imagine somebody providing links, advice, and multiple edits to make sure the question was answered! I'm doing independent study of C.Elegans next semester, and it looks like using those databases for extra gene info would save me... | [
"Oh, man, independent research is awesome -- that's going to open your eyes to the intricacies of science. It's pretty amazing.",
"And, on your point, the gene databases which have cropped up over the past few years are incredible. There are a variety of them for every purpose imaginable -- different species type... |
[
"My son, a fledgling evil genius wants to know what is the deadliest substance known to man. In case he has the chance to hold a city ransom by contaminating the water supply."
] | [
false
] | null | [
"They say \"the solution to pollution is dilution\" so as far as my knowledge goes no small amount of substance could do that unless it was a self-replicating virus or bacteria. ",
"If you wanted to go the most evil route I thing heavy metal poisoning is right up there. Heavy metal poisoning is terrible because t... | [
"Here is a list of LD50 for various substances. Its measured in mg/kg. So that means if you give a bunch of people this many mg for each kg of their body weights 50% will die. ",
"From this it can be seen that giving a person (~70kg) 6.3 L of water would kill. Your son might not need anything, just making people ... | [
"Thanks for the info. I know it will spark a conversation about self replicating viruses. He will think that is really cool."
] |
[
"Why metals are crystalline and not amorphous?"
] | [
false
] | Gibbs free energy equation : G = H - TS, H: Enthalpy T: absolute temperature S: Entropy, Since an amorphous structure has more entropy than a crystalline structure, which should reduce the Gibbs free energy, so why most solids exist in a crystalline state and not amorphous ? | [
"Better, dG = dH - TdS. Now, for the TdS term to be dominating, it needs to be larger than dH. In crystallization, entropy is lost and dS is negative, so -TdS is positive. Meanwhile, dH is always negative for crystallization: the system releases energy when the atoms are locked into the right place, because it's en... | [
"It is hard (read: nearly impossible) to vitrify pure metals due to very rapid configuration to the crystalline state- all bulk metals, when solid, will be crystalline. Funky things can occur at the atomic scale, however. ",
"Alloy systems with very deep eutectics can be turned into metallic glasses, however, w... | [
"ΔG = ΔH -TΔS",
"Since the influence of entropy is ",
" many things adopt a lower-entropy configuration at lower temperature if doing so is more enthalpically favorable than entropically unfavorable (i.e. ΔH<-TΔS). But at high temperatures, -TΔS dominates and they melt (or undergo a phase transition to a more d... |
[
"The earth is often referred in it's ancient state has having been very hot, and it had to cool down before life developed. Why was it hot to begin with?"
] | [
false
] | Was it the impact of all the debris that made up the earth in the first place? Or the gravitational forces between lumps of earth trying to force themselves closer together? | [
"http://www.youtube.com/watch?v=IO45ZiGql8E",
"thats a pretty cool video that explains a little about it"
] | [
"Yes, there is a actually a small liquid core in the moon that hasn't solidified (we just found this out earlier this year!), but smaller bodies cool off faster than larger bodies since they have more surface area per unit volume. "
] | [
"This is horribly wrong. The Earth and Sun were both formed by gravity... but that in no way makes the Earth a former sun (or star)."
] |
[
"What limits the specific impulse of an ion engine?"
] | [
false
] | [deleted] | [
"It depends on the technology you are considering. Gridded ion thrusters (probably what you were thinking about) are limited by the potential difference you can apply to the grids. Ignoring the engineering issues that come with high voltage power supplies in space, the ion current between the electrode is limited b... | [
"To answer your last question:",
"The specific impulse for a rocket is roughly the speed of the exhaust of the rocket, and is ",
" proportional to the amount of energy that must be spent to accelerate the rocket to a given speed. Thus higher specific impulses are very fuel efficient, but very energy ",
".",
... | [
"Picking the best specific impulse for a spaceship is a balance of concerns, where at one extreme you need too much fuel, and at the other extreme you need too much power",
"Yeah that's what I guessed.",
"Interesting perspective with the flashlight, I never thought of a flashlight as having a specific impulse. ... |
[
"Would it be possible for a huge body of free flowing liquid to exist in space (but not in planetary form)?"
] | [
false
] | [deleted] | [
"It would boil (because the partial pressure of the water would be larger than the ambient pressure), then it would freeze into ice (because boiling takes energy, and because the ambient temperature is low), and then it would sublimate into gas (because ice still has a vapor pressure)."
] | [
"The solid-liquid spectrum is a continuum, not a binary distinction. Asphalt at room temperature or below is far on the solid side for practical purposes. It's not going to bubble and boil in space. It's going to sit there, evaporating hydrocarbons very slowly, for a very long time."
] | [
"The solid-liquid spectrum is a continuum, not a binary distinction. Asphalt at room temperature or below is far on the solid side for practical purposes. It's not going to bubble and boil in space. It's going to sit there, evaporating hydrocarbons very slowly, for a very long time."
] |
[
"Is it true that even several hours after heavy alcohol consumption, one can \"sweat out\" alcohol"
] | [
false
] | I drank around 10-11 drinks of beer and whiskey ending at around 2am. I arrived at work at 230 pm the next day, showered, teeth flossed, brushed, had eaten, plenty of water was drank, but my boss insisted that he could smell alcohol on me. he claimed I was "sweating it out" Is there any possibility of this? | [
"Alcohol lost due to sweat is virtually nothing. It's mostly a myth. Nothing significantly decreases BAC other than waiting."
] | [
"It's more likely that he smelled alcohol expelled in your breath."
] | [
"This is just my personal anecdotal experience but you can totally smell it on someone the next day if they have been drinking really heavily. I don't know if they are actually \"sweating it out\" though."
] |
[
"What would happen to a water bottle in space?"
] | [
false
] | [deleted] | [
"Whether the bottle of air, or the bottle of water, would pop would be entirely dependent on the strength of the bottle. ",
"The water wouldn't boil as long as the bottle remained intact, and the water itself under normal temperatures. While the bottle is intact, the water isn't subject to the vacuum of space. "... | [
"is that not a little...chicken and the egg? does the water not push on the inside of the bottle at all?"
] | [
"Of course the water pushes on the sides of the bottle, but if the bottle doesn't break, the water can't be exposed to vacuum. ",
"The strength of the bottle is an important factor, the major factor. "
] |
[
"How close are pro drummers to the actual beat?"
] | [
false
] | Like within milliseconds? Closer? | [
"Tens of milliseconds. See ",
"this article",
" in which the author has plotted the drummer tempo differences for some popular tracks."
] | [
"That's true; depending on the genre, playing a little ahead of or behind the beat is a skill that a talented drummer utilizes. But to have that skill you need the ability to play the beat nearly perfectly before you have the skill to play around with it, so OPs question could still be asked by asking such a drumme... | [
"In most songs, a good drummer would try to add some emotion and emphasis by purposefully not hitting every beat to within a millisecond. That's why a good drummer sounds so much better than a drum machine, I guess."
] |
[
"So how much lithium can we ultimately recover and use?"
] | [
false
] | I am wondering about all the new trends of electrical vehicles, phones, laptops, rechargeable toothbrushes, R/C Toys all using some sort of Lithium-ion or similar chemistry in their power systems. Won't we hit "peak lithium" rather fast? | [
"I'll just quote from a report done by Argonne National Lab on the availability of materials used in Li-ion batteries. You can check out the full report at ",
"http://www.transportation.anl.gov/pdfs/B/583.PDF",
"\"In the case of materials for lithium‐ion batteries, it appears that even an aggressive program of ... | [
"I'm glad you said \"peak lithium\", instead of saying \"run out\".",
"All to often people disregard the effect of supply on price and therefore on demand."
] | [
"Well there are the proven reserves:\n",
"http://en.wikipedia.org/wiki/Lithium#Terrestrial",
"It all depends on economics. The amount of extractable lithium is entirely dependent on the market price. At low prices, only the most concentrated sources are viable. At high prices, very dilute sources are viable. ",... |
[
"Why do Australians have the highest per capita CO2 emissions?"
] | [
false
] | [deleted] | [
"That's probably the main factors I would imagine. No source on anything so take it with a grain of salt - I'm sure others have better information / experience.",
"Source - am Australian, some environmental science experience. "
] | [
"Would our large agricultural industry also ramp up emissions?"
] | [
"False: The plants are going to be eaten by humans or animals that turn them into CO2 again so at best this would be CO2 neutral - but since you use machinery running on fossil fuels you are adding CO2, not removing. If your farm runs 100 % on renewables and you plant trees that stand forever or bury them deep in t... |
[
"Why do we create igM antibodies first?"
] | [
false
] | My understanding is when a t cell activates a b cell it goes into germinal center and goes through class switching. Shouldn't we start off with igG antibodies first? | [
"The first heavy chain exon in the gene's locus is for the μ heavy chain, which is for IgM. The second is δ - IgM and IgD are the first immunoglobulin classes produced by naive B cells. Class switching is primarily deletional, so the exons for μ, δ, etc heavy chains are actually spliced out, so γ-1, α (or whatever ... | [
"IgM is the first antibody to be produced in response to infection since it does not require ‘isotype switching’ to another antibody class. These early IgM antibodies are produced before B cells have undergone somatic hypermutation. However, it is only synthesized as long as antigen remains present because there a... | [
"u/mystir",
" answered it down to the biochemistry components beautifully. To take this further, take a look at a condition called hyper IgM syndrome. These patients lack the ability to class switch antibodies so ONLY have IgMs."
] |
[
"Why is earths gravity so similar to saturn (relative to other planets) when its only a fraction of the size, when the gravity on mars is close to a third of earths when its so much closer in size?"
] | [
false
] | null | [
"Because gravity is a function of mass over radius squared, so whilst Saturn is much more massive, it is also much larger, so the surface gravity is the same.",
"\nBecause the Gas Giants have very dense cores, but very sparse, thick gas layers, at the surface you are far away from most of the mass.",
"\nWith Ma... | [
"Indeed so, but acknowledging that the mass is there but far away was easier for me to explain than saying that planets may as well be eggshells with point masses at their centres."
] | [
"Assuming approximately spherical symmetry",
"Actually, this assumption doesn't work well for Saturn, because it's the most oblate of all the planets.",
"Its polar and equatorial radius are different enough that Saturn's polar \"surface\" gravity is 12.1 m/s",
", while its equatorial surface gravity is only 8... |
[
"How does visual stimuli get stored in genes and subsequently expressed in the brain? (For example, the innate fear of spiders, &/or possible sexual stimuli.)"
] | [
false
] | I'm talking about things like innate fear of spiders: This only seems possible if the brain has "preprogrammed software." Its seems like an image of a spider (or a visual form) has to exist in the mind at birth. It sounds like a memory has gotten passed down from a previous generation. But that is a Lamarckian idea which is generally debunked. How does a gene encode a visual stimuli? Let's say memory cannot be passed down. This would mean there are genes that produce innate fear in random visual stimuli, and the spider-looking-stimuli so happened to get evolutionary selected? i) That seems statistically unlikely. ii) It seems to imply that we would have a storage of innate fears for other random stimuli. We do not have such a storage. I am also curious if sexual visual stimuli is innate (and expressed at puberty.) I am also curious how the brain determines what defining characteristic of a vision is the necessary threshold to trigger fear or desire. | [
"This is a super complicated question since visual stimuli are processed at many levels from the retina to cortex and beyond. I doubt that sexual visual stimuli are innate in humans, but don't think this is known one way or the other. Fearful stimuli are more likely to be genetically encoded via the connectivity an... | [
"I don't see how sexual visual stimuli could be learned. When straight boys hit puberty, they are attracted to women IRL and on pictures. The attraction is strong and immediate. It hits them before they have sex- so there is no reward mechanism involved. "
] | [
"In animal models I would define innate behaviors as naive responses to stimuli that an animal has never encountered before. Let me know if you disagree with that and we can discuss. In humans, it's hard to say whether any behavior is innate because so much information is communicated from parents, friends, media e... |
[
"What's your thoughts on Emergy Medicine (EM) and its use in the East?"
] | [
false
] | null | [
"I was recently given this ",
"article",
" and as I am skeptical of EM, I decided to try and review it. I was advised that the East uses primarily medicine of this nature, and I would love to know a comparative analysis (if that statement is even true).",
"Honestly, it seems like it's overstepping, equating Q... | [
"Hi Headshothero 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 fo... | [
"Medicine"
] |
[
"In the time we've been watching the moon and keeping track of its appearance, have we seen new craters being added to its surface? Aka have we witnessed any collisions?"
] | [
false
] | null | [
"Yup, there are new craters that show up on the lunar reconnaissance orbiter images that did not show before. Here's a NASA link on one example: ",
"https://sservi.nasa.gov/articles/new-impact-crater-on-the-moon/"
] | [
"Here is a video of an impact in 2019.",
"https://www.newscientist.com/article/2191526-a-meteorite-hit-the-moon-during-mondays-total-lunar-eclipse/",
" ",
"The reddit thread.",
"https://www.reddit.com/r/space/comments/ai79zy/possible_meteor_impact_on_moon_during_the_eclipse/"
] | [
"Nice! Thanks for the article!"
] |
[
"When you stub your toes, why does it take a second for the pain to fully hit you?"
] | [
false
] | Maybe this is just me, but whenever I stub my toes (like I just did- ow!) it takes about one second for the pain to fully hit me. It comes like a wave. Why is this? | [
"I do know that a similar experience is putting a foot into a hot bath. It takes a second or so to realise that the water's too hot. I always thought that this is to do with the speed at which the nerves can transmit the sensation to the brain."
] | [
"Im definitely not an expert in this matter but in my experience, when that happens to me, my feet tend to be really cold. So lack of bloodflow to the feet may make the pain receptors slower or less receptive. The impulse to the brain and back to the foot is the same as any bodypart. When touching or jabbing your ... | [
"This is probably not true. If he had stepped on something sharp, the pain would have been immediate. It might have to do with the type of injury - blunt trauma that doesn't break the skin. Can't really offer an answer but I think we can rule out that it has to do with distance from the CNS."
] |
[
"Why are calculations that are fed through a graphics processor completed so much faster then when run through a CPU?"
] | [
false
] | Not completely sure, but I think Sanford's Folding at Home completes basic computations, predictions, and calculations by using the computer's graphics processor instead of the more typical mathematics that occurs within the computers cpu. I get that it runs faster, but I'm not sure why a gpu would be so much faster for completing the computation if the cpu's the normal base. Better put, if the tech on the gpu is better and faster, why don't cpu's use it for everything else they do for computations. | [
"CPUs are more general-purpose. GPUs are more specialized, and they specialize in putting out a massive number of calculations under proper circumstances. The \"proper circumstances\" is the key phrase there. The key thing that a GPU brings is parallelization. It's not that GPUs are faster at doing a single cal... | [
"GPUs do less complicated things, and do a ",
" of them. They're useful for graphics because if you need to do something for each pixel, you likely only have a few multiplications and additions but you have a ton of pixels. And, importantly, the computation for each one is unrelated to the others, so they can be ... | [
"That's exactly what I fucking said.",
"(1) No, it's not, it's the ",
" of what you said. I began the sentence with \"can't\" to indicate that what you said is ",
" the case. Here's a rephrasing for you, to make the meaning clearer: It is not the case that GPUs can complete some operations faster than CPUs... |
[
"To what extent does temperature influence coefficient of friction between two materials?"
] | [
false
] | EDIT: let's assume that the two materials are not nearing a phase change | [
"Anywhere from none to a lot.",
"This question is very vague, so it can't really be answered with any specificity. However, suffice it to say that there are cases where temperature wouldn't change the coefficient of friction, and there are cases where it would significantly change it.",
"Note that in all the c... | [
"This is a super interesting question.",
"Friction is a macroscopic manifestation of repulsion between valence electrons in two materials. Like charges repel, so when the microscopically jagged edges of two materials pass by one another, the repulsion slows them down. What interesting, though, is that we know t... | [
"Hi!",
"I am agreeing with you that the question is very interesting and hard to study, but in recent times a lot has been done to understand friction on the atomic scale.",
"First, you are incorrect in your interpretation of friction as a result of repulsion between valence electrons. The opposite is true! You... |
[
"Why does bad eyesight transfer into mirrors?"
] | [
false
] | null | [
"Focual distance for objects seen in a mirror is distance from eye to mirror + distance from mirror to object. If you are seeing an object that is 10 ft behind you in a mirror, it is as if the object is actually 10 ft in front your in terms of how your eyes are focusing."
] | [
"Thanks for the reply, didn't realize that's how mirrors worked. I assumed they would reflect a perfect image and my eyes then only have the eye to morrow distance to see."
] | [
"Here",
" is a helpful illustration"
] |
[
"If a significant period of time passes since an individual had last used a muscle, can that individual literally forget how to move that muscle?"
] | [
false
] | null | [
"when i read the question i was thinking of something like raising one eyebrow. you would still use that muscle enough so it doesnt suffer from atrophy, but you might forget how to individually control that muscle."
] | [
"Not sure there is a way to know. A muscle will atrophy beyond use before enough time passed to 'forget'.\nI remember seeing this guy on a show a few years back, maybe this will answer your questions.\n",
"http://www.odditycentral.com/pics/indian-sadhu-has-kept-his-right-hand-up-for-the-last-38-years.html"
] | [
"Probably not. Basic use of single and related groups of muscles is hardwired in motor cortex. You have anatomical regions of your motor cortex devoted to specific sets of muscles; the function of those regions is to control those muscles. However, like Calyber said, though you may not forget how to use an unuse... |
[
"Why doesn't plants seem to have an age limit?"
] | [
false
] | I have the impression that plants have no built-in age limit like humans and many animals. If perfect conditions persist indefinitely, it looks like plants can also live indefinitely. I am primarily thinking of trees, but I've read about herbaceous plants that can re-sprout annually, apparently without limits. In humans I've been told that telomeres partly determine the life-span. They reduce in length every cell division, and when worn away, genetic material deteriorate from the edges of the chromosomes. Does plant chromosomes have telomeres? How is genetic material preserved in plants for such long time periods? Does the age of (viable) seeds determine life-span of plants? Some seeds may stay viable for decades and longer, are there any notable differences between two individuals of a species who have sprouted from very differently aged seeds? | [
"I wouldn't say all plants are \"absent of organs\" as spermatophytes do have what are analogous to reproductive organs, but you're correct that a lack of major organs is a big factor.",
"Basically, plants have way fewer types of tissue than most animals do, and one of the other big causes of aging is our bodies ... | [
"You can look at it in terms of a probability. The probability that an event will cause the death of some animal is pretty high, since they have to move around, predation results in death, their systems are more complicated and have more points of failure, they require more energy to power locomotion and brains whi... | [
"I've got no idea what everyone else in the thread is talking about. Plants age slowly because they don't age at all on the cellular level. When they get old and die it's because they get big and gnarled and can no longer sustain themselves properly but their cells are just as young as ever. If you take the newest... |
[
"How do we know that the Ice on other planets consists of H2O?"
] | [
false
] | Watching another run of the mill "Colonize Mars" videos and I heard what I've heard hundreds of times before about there being ice underneath the surface. I remember hearing the same about there being ice on the Moon and even Pluto. I never thought about it before, but how are we sure the frozen liquid we've found is H2O and will be useful in colonization or terraforming? Aren't there many other kinds of frozen liquids this could be? | [
"In many cases it's not H20,but other liquids.",
"It is really just a deduction based on:",
"- What liquids we know are easily formed from chemical reactions or base elements, there are not that many.",
"- What the temperature is on the planet",
"- What temperature those common liquids and elements freeze a... | [
"I learned about this at the Greenwich Observatory. Fascinating, yet very simple. They use a special light filter, a spectrometer. Each element has a unique signature that is detected by the filter. Here is some information about it. \n",
"http://www.scholastic.com/browse/subarticle.jsp?id=2498",
" \nAnd here \... | [
"Yes, of course there can be other liquids too. Wasn't it on Titan where we found liquid Methane?",
"\nAnyhow; the answer to the \"real\" question has two components. First one is probing. If we send a probe to a planet/moon and this probe finds ice, that turns out to be water ice, then of course we know that the... |
[
"Why is mercury-vapor used instead of non-harmful noble gases in lamps?"
] | [
false
] | Why not use gases like Helium, Neon, or Argon in lamps? Instead of mercury-vapor, which is hazardous. | [
" mercury just happens to have atomic characteristics that make it useful for producing visible light at high efficiency, and it is superior to other elements to the point that we use it despite the possible dangers. ",
" in a ",
"gas discharge lamp",
", you pass electrical current through an ionized gas (pl... | [
"Uh ... good question. This ",
"EPA site",
" states that there is such a thing as \"low-mercury\" fluorescents, which leach so little mercury when disposed of normally that they are not regulated as hazardous waste. They still contain mercury, just less of it, along with other chemicals to encourage the mercu... | [
"Mercury vapor gives off uv light which is the right wavelength to excite the phosphor coating on the inside of fluorescent tubes. None of the noble gasses emit a white light which is comfortable to the eye. "
] |
[
"If you could download the schematics of every part of a car, could you make a functional car with a 3d printer?"
] | [
false
] | [deleted] | [
"http://gizmodo.com/5678476/the-worlds-first-3d+printed-car-actually-works"
] | [
"I'm not sure I'd take a Fast Company press release too seriously -- it's pretty much an advertising site aimed at venture investors. I note that their web site doesn't repeat any of these claims about 3-D printing.",
"With that said, it would certainly be possible to 3-D print a range of exterior and interior pa... | [
"but to make something like an engine block would be difficult",
"Use a metal printer then (yes they do exist), or CNC the engine block from a solid piece using a 5 axis CNC machine. Not a printer since it's not an additive process... but it gets the job done."
] |
[
"Why does bad eyesight persist in humans?"
] | [
false
] | Why does bad eyesight persist among humans despite evolution or natural selection? Seems like it would have beared strongly on survival and reproduction of our ancestors and the trait would have been removed. | [
"Well, for most people, the onset of bad eyesight doesn't occur until middle/late age. The evolutionary pressure against it only lasts until after prime breeding age. ",
"\"Evolution doesn't care about organisms, it only cares about genes.\"* Thus, if you can pass your genes on before problems develop, there's no... | [
"Here is an article on just that in the ",
"New York Times: The Sun is the Best Optometrist",
"Some quotes:",
"in the early 1970s, 25 percent of Americans were nearsighted; three decades later, the rate had risen to 42 percent, and similar increases have occurred around the world.",
"In this case, the rapid... | [
"I'm not a biologist, but it seems to me that the eye is a pretty complex work of evolution, and should we have imperfections in other parts of the body (we all do), that it's pretty likely the eye may not develop PERFECTLY also.",
"As far as survival goes, the ability to see vs. the ability to read tiny print on... |
[
"Does the procession of Earth's axis have any effect on the climate?"
] | [
false
] | null | [
"The precession of the Earth's rotation axis is one of several factors that enter into the ",
"Milankovitch cycle",
"."
] | [
"Perihelion (closest approach to the Sun) tends to occur during winter in the northern hemisphere, while aphelion (greatest distance from the Sun) occurs during summer in the Northern hemisphere.",
"The Earth's ",
"next perihelion",
" is January 2, and the next aphelion is July 5."
] | [
"Wow, only one answer but it's a good one. Thanks!",
"Bonus question edit: Do you know if we are currently in perihelion or aphelion?"
] |
[
"How do you cool things to extreme low temperatures +1-2K?"
] | [
false
] | null | [
"For anything below liquid helium temperature, generally laser cooling is used. There are many different mechanisms for exactly what physical properties are used. The general principle is that you shine photons at very specific frequencies, so that the material is more likely, on average, to give momentum to the ... | [
"Cooling things to extreme low temperatures is a very long, tedious process, but shockingly enough, 1-2k is not really \"extreme(ly) low.\" If you have just a nice bucket of liquid helium, that helium is around 3.5k, then using a \"simple\" ",
"Evaporative cooler",
" you can actually cool something down to .3K,... | [
"Yes, that is about the best we can do. Our instruments like to be around 4K to 10K depending on the instrument.",
"Of course, we are doing this at 13,796 ft - which helps quite a bit."
] |
[
"Why do things like saliva or melted cheese pull into strings when you try to separate them?"
] | [
false
] | null | [
"Saliva \"pulls into strings\" due to water's property of ",
"cohesion",
" (saliva is over 99% water), as well as the mucus content in the <1% non-water part. Miscellaneous proteins also composing the admixture may increase saliva's \"stringy\" properties.",
"Melted cheese \"pulls into strings\" due to its m... | [
"The cohesion of molecules of pure water cannot resist the adhesion forces between the water mass and the object touching it. The mucus content of saliva adds to that cohesion and causes the \"stringy\" effect."
] | [
"Saliva \"pulls into strings\" due to water's property of cohesion",
"If it was due to that, water would also behave similarly, and it obviously doesn't."
] |
[
"Does Eating Healthier Disproportionately Affect People of Low Income?"
] | [
false
] | Hello folks. I always hear that eating vegetables is better for the body and that we should eat more of them. However from an economic standpoint, is it actually feasible for people with a limited income or people that are struggling economically to purchase healthier foods like fruits and vegetables over unhealthier processed foods like easily prepared mash potatoes or fast and ready mac and cheese? I'd like to hear people's thoughts on this as I have been trying to research whether eating healthy is actually feasible economically. | [
"It is possible, but increasingly difficult as you go lower down the levels of economic stratification. Not only is price an issue, but in low income areas, it is common to find ",
" These are areas where there is limited or no access to healthy food at all. Think of a slum with only a corner store and MacDonalds... | [
"I would add that prep time is also an issue the further down the economic line you go"
] | [
"The guardian piece puts it well. They describe it along the lines of: a project that is described as a hobby or stress reliever in the affluent becomes another time consuming stressor in the poor."
] |
[
"Does the centripetal force of Earth's rotation make you lighter at the equator than at the poles?"
] | [
false
] | I was bored at work one day and thought of this. My buddy who has an engineering degree worked some math on the back of a paper plate (sadly misplaced now) and told me that the average person will indeed be a few pounds lighter (depends how much you weigh in the first place) at the equator as centripetal force combats gravity somewhat. Thought I would see if his conclusion holds up to scrutiny by the larger community. | [
"and told me that the average person will indeed be a few pounds lighter (depends how much you weigh in the first place) at the equator ",
"Actually, the difference in a measured weight between the north or south pole and the equator, arising both from ceptripetal force and the earth's oblateness, ",
"is about ... | [
"It is true that due to the centri",
" force, in the frame of reference rotating with the Earth you will in fact be a little bit lighter at the equator. In an inertial reference frame, some of your gravitational attraction to the Earth is being used as a centri",
" force to keep you rotating with it. "
] | [
"Neil Tyson has answered this very question in many of his talks, which you can find on youtube, and yes, you are lighter at the equator than at the poles. He mentioned hypothetically, you could speed up the rotation of the earth and make it so that people at the equator would essentially be weightless. But people ... |
[
"What happens when there are two, different dominant alleles in the genotype?"
] | [
false
] | [deleted] | [
"The short answer: It's likely co-dominance. ",
"I'm not a geneticist, but I know enough to try to answer your question. I will also try not to over generalize this question because the genetic mechanisms at play are not always as simple as one just being dominant over the recessive (such as functional gene vs de... | [
"It depends, say you have a white mouse and a black mouse with both color traits being dominant. If the offspring are grey, then you have incomplete dominance, which is characterized by a blending of the traits. If you wound up with a spotted black and white mouse, then it would be codominance."
] | [
"None of these answers really answer the question very well. It's more useful to think of ",
" or ",
" as being dominant or recessive rather than individual alleles or genes. An allele is a variant of a gene that produces a protein. You can have different alleles at different loci within that gene that cause di... |
[
"Do my brother and I share the same genes?"
] | [
false
] | I guess I am not yet clear about DNA and genes. My brother and I clearly must not share the same genes because we are different people. Then, this must mean that every sperm/egg's DNA/gene (?) content is unique. If that is the case, then when someone performs a DNA test, what are they getting? | [
"You have received half your father's genes and half of your mother's genes.\nIt's the same for your brother, but with different halves.",
"In the end, it is highly improbable that you received exactly the same genes or totally different ones. In average, two brothers share 50% of their genes."
] | [
"Genes are the bulk of the \"data\" stored on the DNA. There are other important elements that are called non-coding, because they are typically not ultimately translated into proteins. However, they play important roles in the regulation of gene transcription, for example.",
"All humans share an almost identical... | [
"The three responses you have so far are correct to some extent but may also be a bit confusing. All three leave out the reason why some of your genes aren't even the same as any of the genes your parents have.",
"To answer your question more directly: your brother and you share about 50% of your genes. About hal... |
[
"Why do power plants need cooling towers?"
] | [
false
] | Why does the steam after going through turbines and then condensers needs to be cooled by cooling towers? Wouldn't it be more efficient to pump hot water into the boiler to generate steam? My preliminary research shows, there are such systems as closed circuit that does not use cooling towers. I would think this was the obvious choice. What then, would be the advantage behind the design with cooling towers and open circuit water system. | [
"There are two different things going on here. All “heat engines”, and a power station is one, need to dump waste heat in order to be efficient. That might be done by ",
"a conspicuous cooling tower, or some other way",
", but it's always done somehow. As the wiki articles says, if the power station has access ... | [
"It's cooling the steam that has already been through the turbine to convert it back to water. The water has a MUCH smaller volume than the steam and is easier to pump back into the boiler."
] | [
"Yeah, but the Carnot cycle describes a perfect heat engine, doesn't it? "
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.