title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How can computers be able to calculate when they are only a bunch of inert materials connected via electricity ?"
] | [
false
] | null | [
"Hi ",
"/u/lucasmoulinx",
" ,",
"Unfortunately, there's a lot of misconceptions in your question. Let me try to point you in the right way:",
"A Turing machine is a model of computation. It is not real, most prominently because it possesses an infinite tape (storage). Contemporary computers are classified/m... | [
"Hello and thank you very much for taking the time to answer my question. I understand that computers cannot think, but what I meant was how are they able to make a choice or to select information by themselves? Again I am not certain to be clear or that my question even makes sense. Maybe I should as you said make... | [
"Off-hand; I assume you have some sort of high-level overview of what a computer can do, but lack the low level insight. If so, I usually recommend ",
" by Tanenbaum. It will most likely be available at your local library, and parts of it may be available online as well.",
"You may also want to look at courses ... |
[
"Is Turritopsis nutricula (the \"Immortal Jellyfish\") really immortal?"
] | [
false
] | As far as I understand, the "Immortal Jellyfish" can go back from being an adult to an infant, repeating this process indefinitely. Since most regular Jellyfish are doomed to die after a specific amount of time after reaching adulthood, this mechanism grants the "Immortal Jellyfish" as many life cycles as it wants. But... | [
"From the Wikipedia article you've mentioned:",
"Studies in the laboratory showed that 100% of specimens could revert to the polyp stage, but so far the process has not been observed in nature, in part because the process is quite rapid and field observations at the right moment in time are unlikely.[3] In spite ... | [
"I hate that I can't make a joke about my name in this subreddit!",
"It is biologically immortal, yes. So it has chance of living forever, albeit a small chance."
] | [
"Of course! Death erases 100% of your previous life, so even a regenerative process that takes away 100% of my life would be no worse than death, with the potential for it to be better since I could learn about my previous self and thus have some continuity along with a fresh start."
] |
[
"The observable universe vs. the entire universe"
] | [
false
] | I was reading something and I thought.. "if we can't see past the observable universe, then how can we estimate a size of the universe?" Several sources later.. I took many things in from them, but some parts sounded like they were making up words. Help me out here, I'm explaining it in my own words the best that I can... | [
"the entire universe is estimated at 93 billion years",
"Who says that? Even if you mean \"light years\", the universe is usually assumed to be infinite. Are you talking about just the observable universe?\nThen that number is not measured, but more calculated based on other measurements and the theory of general... | [
"The people who made that flash applet obviously are not cosmologists. They apparently stumbled upon the number of 93 billion ly and thought, \"if the universe is only 14 billion years old, how can that be the observable universe?\" and thus came to the conclusion, that the observable universe is 14 billion ly in s... | [
"Point is, no serious scientist will conclude something they have zero information about. Almost every interview I read by a physicist answers the \"is the Universe infinite?\" question with \"we don't know\". That really is the only correct answer with our current level of understanding. ",
"It's like we are ant... |
[
"Our internal body temperature is 98.6 F, so why does it feel so hot when it's that temperature outside?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"medical advice",
"/r/AskScience",
"Please see our ",
"guidelines.",
"If you disagree with this decision, please send a message to the moderators."
] | [
"I understand the guideline against medical advice, but I would argue that feeling hot when it's 98 degrees outside is not a medical condition, but rather is how most humans experience the world. Similarly, most feel cold when it's under 0F outside. Maybe not all, but certainly most.",
"I'm open to being persuade... | [
"Oops! I'm sorry, I accidentally selected the incorrect response message (there are several when removing a post) -- I meant to select the one that said that this is a fairly common question and that you can find the answer by searching in the search bar for something like \"98 body temperature\". Unfortunately, be... |
[
"How dark is space?"
] | [
false
] | Say I was floating around in deep space but protected in a space suit, the victim of a terrible star trekking disaster. If I was stranded far away from any known star or solar system, Would I be able to see my hand infront of my face? Would the ambient universal light from distant stars provide me with enough light to ... | [
"As another post mentions, a good rule of thumb might be taking night-time with no light pollution, during a new moon. (I would add no planets here as well.) I poked around for some numbers... (Here: ",
"http://www.ee.ryerson.ca/~phiscock/astronomy/light-pollution/photometry.pdf",
")",
"What we're looking f... | [
"I'm not going to run numbers here, since the question is a little vague. This depends entirely on your definition of \"deep space\". If you mean, say, moving 4 or so light years away from our solar system and keeping that same distance from any other stars, then you're essentially talking about going to a dark s... | [
"But what other galaxies could we see? ... Turns out only a handful can be seen.",
"So, essentially, any future intergalactic traveler would never see a view like ",
"this?"
] |
[
"How much gravity does an object need to visibly bend light waves?"
] | [
false
] | I know that dark matter bends light (gravitational lensing), but what is the lower limit for this kind of thing? Does the Earth have any effect on light waves? | [
"It does, but being able to see light bending depends a lot on the position of the viewer, in addition to the mass of the object. Gravitational Lensing in most of its classical examples like ",
"this",
" dramatic distortion happens with a galaxy billions of light years away. Light travels extremely fast, so the... | [
"Thanks for the informative response!",
"Follow up question: can gravity affect sound waves the same way it does light waves? Given it was in a non-vacuum area of space and the object would not obstruct the path of the sound wave directly."
] | [
"Well, sound waves are, by definition, pressure waves in a material (normally air for us humans). So the way a sound wave travels depends on the type and shape of the object or medium it is passing through. If an object is shaped or distorted by gravity, it will have a corresponding effect on sound waves that trave... |
[
"How can sound travel as light in an optical cable? And does that mean the speed of sound can be increased beyond the sound barrier?"
] | [
false
] | null | [
"Where did you hear that “sound travels as light”?"
] | [
"I was just assuming that since light is involved at both ends and the cable is optical based that the sound was traveling in the form of light"
] | [
"What sound? It’s light everywhere."
] |
[
"Why can't I receive information from the future via delayed choice quantum eraser with a different beam splitter?"
] | [
false
] | It seems that you cannot send information to the past (aka receive information from the future) with delayed choice because the waveform interference pattern cannot be understood with the screen alone because you need to first examine the detectors to make sense of the dots on the screen. The current thinking seems to ... | [
"Ok well I've explained it 3 ways now, why your setup doesn't work and where your thinking is wrong. You don't seem to accept it, but at least keep in mind: either you've misunderstood or there is a trivially easy way to send FTL signals that has gone unnoticed by the worlds best and brightest for 100 years..."
] | [
"Then you just have an almost totally unorganized blur for your C post selections, and basically a blank screen for your D post selections. The photons state is a 50-50 superposition for the two patterns (fringe/antifringe), the BS doesn't assign the state, just sorts (trasmits or reflects) based on it/in proporti... | [
"No, I just always receive the unfiltered C+D combined pattern, which is always a blur/blob. Nothing you do before or after can change this for me. I can't filter my measurement result to just the subset of my photon impressions that paired your Cs until you tell me which ones were Cs for you. For which you will... |
[
"Why are \"god rays\" (light rays coming through clouds) not parallel but seem to come from a point light source much closer than the sun?"
] | [
false
] | null | [
"They ",
" parallel. Think about what happens when you look at a long set of parallel lines, like a railroad track. ",
"They look like they converge",
" in the far-off distance. That's why the rays that you see appear to diverge from a point.",
"PS The scientific name is ",
"crepuscular rays",
".",
"E... | [
"Thanks for the new wallpaper!",
"Hecklingfern has it right - those sun rays only look like they're vertical. They're actually angled. Something you learn when you start following weather around in the summer is that distances in the sky are very deceptive. The supercell thunderstorm that looks like it's almost r... | [
"Thanks for the new wallpaper!",
"Hecklingfern has it right - those sun rays only look like they're vertical. They're actually angled. Something you learn when you start following weather around in the summer is that distances in the sky are very deceptive. The supercell thunderstorm that looks like it's almost r... |
[
"Is it possible to see nerves in a cut of meat from the grocery store?"
] | [
false
] | Obviously in various cuts of meat you can see skin, bone, muscle, fat, tendons, ligaments, etc. Is it possible to see nerves too? This is the closest I'll ever get to dissection/surgery so I'd like to make the most of it! | [
"Yes. Nerves veins and arteries usually are bundled together, in a sheath, through muscle groups.",
"The sciatic nerve, forms around the level of the gluteal muscles and goes down the leg, is quite large above the knee.",
"So I'm thinking ham hock?"
] | [
"Yes, I believe so. I've never slaughtered a cow or pig myself and I don't really know how the locations of the particular cuts work out, but judging from the size of some human nerves (brachial plexus, sciatic, etc.), it should definitely be possible to see some in a cut of beef or pork. ",
"Here",
" is a labe... | [
"In some cuts, yes. For example, I like to smoke pork shoulders, and I have found remnants of the brachial plexus in some. I think they generally try to cut temp out, though."
] |
[
"Explain Antimatter and Matter to me."
] | [
false
] | I know there's a lot of material out there on Antimatter and Matter, but most of it is extremely technical and precise. This isn't a problem, but it also isn't what I'm looking for. I'm looking for the explanation you give to Timmy, Kid Physicist. He's seven years old, likes penguins, and wants to know more about the... | [
"Here you go, Timmy."
] | [
"Well here's the basic idea:",
"Think of your basic particles subatomic particles - proton, electron, neutron. (Protons and neutrons have further sub-particles, but we'll ignore this.)",
"Antimatter is still ordinary matter. It doesn't have negative mass. It isn't repelled by gravity. It's just opposite charge.... | [
"I would say even a teaspoon's worth would be orders of magnitude to large."
] |
[
"Are there any gemstones that have applications in the scientific community?"
] | [
false
] | null | [
"There's lots of instrumentation made out of precious gems. Examples include ",
"diamond anvil cells",
" for examining extremely high-pressure compounds, ",
"diamond and sapphire lenses",
" used for camera optics that can function at Venus surface temperatures, as well as ",
"ruby lasers",
"."
] | [
"It was natural... and, aparently, it's an interesting case in ",
"tax law",
" (!!??).",
"When you import optical elements to the US you had to pay taxes on it, and if you \"re-exported\" them later you got your money back. So a lawyer for the Hughes Aircraft Company had to argue that launching a probe is the... | [
"Within geology there are a number of precious and semi-precious stones that are useful in determining the geologic history of rocks and regions. In many cases, aspects like the trace element geochemistry (e.g. relative abundances of things like light and heavy rare earth elements or isotopic composition) or the ge... |
[
"What is going on neurologically when you switch from voluntary to involuntary breathing?"
] | [
false
] | Have there been imaging studies of the respiratory center while this takes place? | [
"See this previous post",
"Brainstem respiratory neurons control automatic breathing. When you begin to breathe 'consciously,' this voluntary breathing is initiated by the cerebral cortex but interacts with automatic breathing via projections from the cortex to the brainstem respiratory centers. For example, cort... | [
"More like those patients have to be ventilated."
] | [
"You can have lesions that affect voluntary breathing but not automatic breathing, lesions that affect automatic breathing but not voluntary breathing, or lesions that affect both types of breathing",
"Do people get lesions on their automatic breathing, meaning they have to be permanently aware of their breathing... |
[
"Since antibiotic-resistant bacteria are often less competitive than other species of bacteria, could introducing another bacteria that is harmless to humans but can outcompete the resistant bacteria be a useful treatment for multi-drug resistant infections?"
] | [
false
] | null | [
"http://www.sciencemag.org/content/312/5782/1944.short",
"\"Antibiotic resistance is also often associated with a reduced competitive\nability against antibiotic-sensitive strains, in the absence of the antibiotic\""
] | [
"Since antibiotic-resistant bacteria are often less competitive than other species of bacteria",
"Source?"
] | [
"That is primarily because it cells that are antibiotic resistant have to expend energy and nutrients to being antibiotic resistant. ",
"However, your idea does not take into account that nearly all antibiotic resistance is acquired by bacteria horizontally--that is, susceptible bacteria acquire genes for resista... |
[
"What happens when something hits the edge of the universe?"
] | [
false
] | null | [
"As far as we know there is no end to the universe. "
] | [
"It isn't an intuitive result, without studying the subject, I don't think anyone would have good reason to understand the result."
] | [
"Yeah. But what happens. I don't want to fall out. "
] |
[
"Why do planets orbit elliptically?"
] | [
false
] | [deleted] | [
"You don't need relativity to explain elliptical planetary orbits",
"."
] | [
"An ellipse is the most energy efficient shape for an orbit. I think the easiest way to explain it would be to point out that an oval is composed of the intersection of 4 circles, of 2 different radii. Each point on the oval is exactly the distance of the radius from at least one circle. The arcs of each circle joi... | [
"A shape that would not conserve angular momentum would not be energy efficient, would it? An oval would not conserve angular momentum, but then one might ask why ",
" is. I tried answering the question without talking about conserving angular momentum and avoiding the acceleration that would cause the change in ... |
[
"Do cars in higher elevations get better gas mileage?"
] | [
false
] | I’d think so, because there’s less air to create drag, but then again, maybe less/thinner air affects the engine somehow. | [
"You're right to point out that it's a combination of both factors. Fuel efficiency goes down since there's less oxygen for the combustion (although with a turbo the effect may not be so simple) but in spite of this mileage will go up because drag goes down massively. Since drag is involved it's going to depend on ... | [
"You're right to point out that it's a combination of both factors. Fuel efficiency goes down since there's less oxygen for the combustion (although with a turbo the effect may not be so simple) but in spite of this mileage will go up because drag goes down massively. Since drag is involved it's going to depend on ... | [
"This is one area where electric cars have a major advantage.",
"The \"Hot/High\" problem decreases internal combustion engine performance, which is only partially offset by decreased air resistance. This is a major thing for aircraft.",
"Electric cars on the other hand lose no power due to altitude or temperat... |
[
"Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"Cure is a bit strong of a word. THC has anti-cancer properties, and there have been many studies on it.",
"Head and neck.",
"Lung cancer",
".",
"Breast cancer",
".",
"There are many more, if you want I can provide some. The biggest problem is that there are some inconsistent methodologies giving somewh... | [
"Are male and female brains different? Like, could a very educated and experienced neuroscientist look at scans and data etc., and tell them apart? ",
"Edit: And if so, when do the differences become apparent? Puberty? And what does the brain of a person identifying as transgender. - like Jenner , who specificall... | [
"Yes the newest hypotheses is that so called ribozymes are RNA molecules with catalytic properties, these are thought to jump start the whole central dogma."
] |
[
"If carboxylic acid is created spontaneously when water is left in a beaker for a day or so, why isn't the world's lake all carboxylic acid?"
] | [
false
] | null | [
"You mean carbonic acid.",
"The reason is that only limited amounts of carbon dioxide are absorbed in water to begin with. The amount of carbonic acid is limited by the equilibrium of dissolved carbon dioxide, bicarbonate ion, and carbonic acid."
] | [
"Yes, because with more carbon in the air it shifts the equilibrium so that the water will take in more carbon as well therefore having higher concentration of carbonic acid."
] | [
"that's not at all true. CO2 in the ocean is rising rapidly in response to atmospheric increase in CO2.",
"https://ocean.si.edu/conservation/acidification/ocean-acidification-graph"
] |
[
"What's going to happen to the polar bears as the ice caps shrink? Evolution or extinction?"
] | [
false
] | I watched a show recently describing how as the sea ice melts earlier, polar bears are going to be threatened because they won't have enough time to hunt enough seals to build up their fat stores for the summer months. This made me wonder, as the earth warms further what will happen to polar bears? Will they simply go... | [
"Well extinction is a distinct possibility as a loss of sea ice results in very large evolutionary hurdles. On the other hand with less ice and snow, selection pressures favour darker bears, and as they can interbreed with grizzlies its possible they might just converge back into a single species."
] | [
"Extinction is not evolution. Evolution can only occur if the DNA is passed on. That is using evolution in the strict sense. "
] | [
"upvoted for reference to pizzlies."
] |
[
"How/why did the original continental landmass, Pangaea, form?"
] | [
false
] | Are there any theories out there that provide insight in to the formation of land on our planet, and why it started out as a single, large mass of land? | [
"Pangea was not the first supercontinent in Earth's history. Supercontinents, as you probably know already, form when several regular continents collide and stick together. There is something known as the supercontinent cycle where, about every 300 to 500 million years, the Earth's continents all join together to... | [
"This is a good question and one I would like to take my time with. I'm a little preoccupied so I'll get back to you on this."
] | [
"This is a good question and one I would like to take my time with. I'm a little preoccupied so I'll get back to you on this."
] |
[
"So Voyager has left the solar system. Could we catch up with it if we wanted to do a targeted exploration?"
] | [
false
] | Voyager was a craft designed to examine the outer planets, so I'm guessing it has very limited instruments left that can measure interesting things about space outside the heliosphere. So if we wanted to send out a craft specifically to explore the environment in interstellar space, would it take another 37 years to ge... | [
"of course we could. We could it even in the 70´s. its just a question of money.\nThe speed you need to leave the sun Gravitation is around 46 km/s. Because the earth spins around the sun you just need 16 km/s.\nVoyager 1 and 2 both use a multi slingshot acceleration flight plane where jupiter and saturn both gave ... | [
"Voyager took advantage of several gravity assists (using planetary gravity as a 'slingshot' of sorts) and a good alignment of planetary orbits to achieve escape from the solar system.",
"The planetary alignment is kind of a only happens once every N years kind of thing. ",
"We don't really have technology yet ... | [
"With conventional technology, yes, it'd take that much unless you want to spend billions to use a huge rocket. But a couple of modern concepts using solar energy could be faster. Take a look at ",
"this thread",
" for details."
] |
[
"If i had a bowling ball in the middle of outer space. Could a m&m orbit around it?"
] | [
false
] | What size ball would you need to get something like an m&m to orbit around it? | [
"Yes, but very slowly.",
"A plain old circular orbit is described by the following equation:",
"a = w",
" r",
"with a being the acceleration (in this case, due to gravity), w the angular velocity (in radians per second, for reference: a full circle corresponds to 2 pi radians) and r the orbital radius.",
... | [
"Worth noting that you have to give the m&m just the right push to put it in the orbit around the bowling ball. The escape velocity is sqrt(2GM/r), which for a 7 kg bowling ball at a distance of 1 m is just 0.00003 m/s. (G is 6.67e-11 m",
"/ kg s",
".)",
"Any faster initial velocity (from 1 m from the center ... | [
"It is absolutely possible to position something with 30nm accuracy with the right tools, and sub atom accuracies are doable with the right instruments."
] |
[
"Could Someone please explain to me the science of the octave in music?"
] | [
false
] | null | [
"First let's explain the science behind a \"note\". A note is just a name given to a particular frequency of air vibrations, which is what gives that note its tone. For example, an A in the middle of the piano in standard tuning is nothing more than a vibration at 440 Hz, meaning when that key is pressed on the pia... | [
"It all boils down to a mathematical concept called \"Fourier transformation\". This guy named Fourier figured out how to turn any series of values (like the pressure in air at subsequent points in time) into a collection of pitches. That turns out to be extremely useful for many things. ",
"One of the cool th... | [
"Of the various harmonic relationships such as octave (2:1), perfect fourth/fifth (3:2), perfect third (4:3), why do we perceive only the octave to be the \"same\" note?"
] |
[
"In sample standard deviation, why do we divide by (n - 1)?"
] | [
false
] | I understand that it is because of the sample size generally being lower than the population average, hence we just minus one from in order to obtain slightly more accurate results to emulate the population. However, I don't understand why 1 was chosen. Does anyone know the origin of the choice of the number 1? Why not... | [
"This is a sort of boring answer to your question sadly, but here it goes:\nSo let's say you try your first instinct and choose to divide by n. Then following a lot of algebra, you see that your expected sample variance will be (n-1)/n * (sigma), where sigma is the true variance. See here for details: ",
"https... | [
"According to the textbook I am studying, \"probability and statistics for scientists and engineers\" page 15...",
"It should be clear to the reader that the sample standard deviation is, in fact, a measure of variability. Large variability in a data set produces relatively large values of (x-x)",
"[I don't kn... | [
"This is the right answer, however I'd add that there is an intuitive interpretation behind this.",
"Think about it this way, what would the standard deviation of a sample of size one be? It should be undefined, because the idea of standard deviation doesn't make sense with only a single sample. Dividing by (n-1)... |
[
"What exactly is the 4th Dimension?"
] | [
false
] | Ok so my basic understanding from Carl Sagan videos and other things like that is that it is just a higher spacial dimension than ours. But why do we think that it exists, what evidence has pointed us to thinking that there is a 4th dimension. And why is time associated with it? Is it just because its the next logical ... | [
"So let's start with space-like dimensions, since they're more intuitive. What are they? Well they're measurements one can make with a ruler, right? I can point in a direction and say the tv is 3 meters over there, and point in another direction and say the light is 2 meters up there, and so forth. It turns out tha... | [
"The point of t being ",
" (you can equally call t+ and space-, and we choose this convention often times when we work with energy and momentum) is that it creates what's called a \"hyperbolic\" geometry. so if a line of constant distance from the origin in \"standard\" geometry is given by sqrt (x",
" +y",
"... | [
"There's two different concepts here. One is that the universe has three spatial dimensions and one time dimension, so that \"The ground floor of 3rd street and 5th avenue at 7 PM\" is a four dimensional coordinate. The is other is four dimensional space, which is a mathematical construction."
] |
[
"If I was floating in space and didn't have a point of reference, would I be able to tell if my body inverted 180 degrees from my original position?"
] | [
false
] | null | [
"You could tell if you were holding a gyroscope."
] | [
"if you were slowly rotating in space with no reference points then you would not know you are rotating because your 'state' never changes; you are always rotating and always will (until you are nudged still again).",
"Not true. Rotation will always have centripetal acceleration and consequently a measurable forc... | [
"most likely yes. in order to invert your body a force would have to be applied to start moving you and then another force to make you stop moving and those forces would be felt (nudge on your shoulder or stabilizer firing), this would by a dynamic system. but if you were slowly rotating in space with no reference ... |
[
"Why do car engines 'tick' after being turned off?"
] | [
false
] | null | [
"When the engine is running, it will heat up itself and the components near it. Heating something causes it to expand. Once the engine is turned off, it will cool down again which causes the materials to shrink back to their original state. The different parts of the engine are made of different materials, so the h... | [
"That's true. That's just one part ticking then. If you had multiple parts of different size all cooling and snagging on friction at the same time, it wouldn't be a constant function. Adding multiple parts would increase the degrees of freedom in the heat transfer rate equations, and you would have some ridiculous ... | [
"the repeated ticking that I hear after turning my car off in the summer is evenly paced ticking. I doubt that internal parts all cool at the same rate (1 per second for ~20 seconds)?"
] |
[
"Why can't powerbanks charge while being charged?"
] | [
false
] | null | [
"They can. For instance, most cell phones can be used while charging. This is generally called \"pass-thru\". Unfortunately, with external batteries, most manufacturers and/or retailers don't actually say which support it. ",
"The reason it's not universal is because it creates more of a thermal load, since twice... | [
"Forgot to provide my link...",
"https://www.pcmag.com/roundup/351446/the-best-battery-packs-for-your-phone",
"Not exactly a wide selection, but if you're looking for one, hopefully it'll give you a start."
] | [
"It's only more complicated if you are making unsafe batteries. A pass through battery with the appropriate safety considerations is more complex than one without."
] |
[
"Why You Can't Tickle Yourself"
] | [
false
] | [deleted] | [
"Is there a question here?"
] | [
"Someone posted a few days ago with a question about tickling and since I went to the trouble to type this up for an answer I figured I'd see if anyone appreciated me posting it."
] | [
"TL;DR so i tickled myself on the foot and it worked. qed"
] |
[
"Do a freshly laid egg and a freshly hatched chick have the same number of calories? If not, where do the extra calories come from?"
] | [
false
] | If the chick has more calories, it must be getting the extra energy from somewhere...? | [
"No, the egg would have more calories. The egg has all of the materials, including energy, needed to form the chick. The process of forming the chick involves chemical reactions that are driven forward by the use of the stored energy. The process is not 100% efficient and the energy lost escapes from the egg as hea... | [
"Nope. You need a temperature differential to do work. The mother bird is just making sure the eggs don't lose heat."
] | [
"Bird eggs have no mechanism to convert heat energy into something like glucose that is usable for metabolism. If a mother bird sits on an egg and warms it, it transfers energy to the egg in the sense that it warms it up, but that energy is simply the heat in the egg, and is lost when the egg cools down. It's not... |
[
"Can gravitational waves escape black holes?"
] | [
false
] | null | [
"No. Nothing can."
] | [
"...sorry what? Plane of existence? "
] | [
"This is ",
". If you set up your weak field theory around a background like so",
"g = g_0 + h, h << 1",
"You'll find h features waves that move in the bg metric g_0 and are affected by it."
] |
[
"[Medicine] Improper alcohol detoxification can kill a person. How then can people rehabilitate alcoholics?"
] | [
false
] | null | [
"have them (the addict) continue to consume alcohol as needed to avoid serious withdrawal symptoms.",
"However, the amount consumed per day is decreased continually over a span of several days, so that their dependance on ethanol is gradually reduced to zero."
] | [
"Switch to other longer acting drugs that work on the same receptors (diazepam or other benzos) and then taper down the dosage at a safe and tolerable rate. Cold turkey is very rarely an effective method of overcoming moderate-severe cases of physical dependency because even overlooking the risks of seizures and st... | [
"In the hospital for the treatment of acute moderate or severe alcohol withdrawal, there is usually a \"detox cocktail\". This main aim is to treat/prevent seizures, lower craving, and supplement vitamins to prevent encephalopathy. ",
"To prevent seizures/craving from acute alcohol withdrawal, you have benzodiaze... |
[
"I've read that certain sharks will kill their siblings before birth. What purpose does this behavior serve, and isn't it a waste of resources for the mother?"
] | [
false
] | null | [
"Remembered this from an animal behavior course:\n",
"http://en.wikipedia.org/wiki/Siblicide",
"I'm pretty sure this is obligate siblicide. The surviving shark will typically be the stronger of its siblings and will have gained resources. ",
"You can think of it as way to have more biological diversity. Inste... | [
"the question isn't \"what is best for sharks as a species?\"",
"the question is \"what genes are best at surviving?\"",
"a shark that eats it's siblings is going to have less competition and do better for himself, assuming that sharks don't help each other out very much. if so sharks that do such a thing are ... | [
"This is what it's all about. Selection favors genes that survive, not necessarily genes that benefit \"the species\"."
] |
[
"How hot are the coals in the coal bed of a campfire that has been burning for a while?"
] | [
false
] | We were camping on the weekend and a few of us thought around 500-600 degrees celcius, some thought over 1000 degrees celcius. | [
"Wood coals burn at 3-600 degrees. You can get them hotter by providing lots of oxygen (like in a blacksmith's setup) but the way to tell is by the color of the coals. \nBased on the Black-body radiation (since coals are black, this is a good approximation) you start to see a glow at about 500 deg C, and it is easi... | [
"It should also be noted that coals which have burned for a while will be covered in ash, which will make approximation by color difficult. If the coals are from wood, the type of wood and dryness will also affect how hot it burns.",
"And yes, over a small fire you'll likely never melt foil - just build a bigger ... | [
"Thank you!"
] |
[
"How does putting a phone into a ceramic bowl amplify sound?"
] | [
false
] | Recently I saw that you could make your own "speaker" by putting a phone into a ceramic bowl, how does this work exactly? | [
"Sound waves spread out in all directions and bounce off of solid surfaces. So if you put your phone in a bowl, the sound bounces off all of the interior surfaces of the bowl and exits out the open side. The bowl basically works kind of like a lens for sound waves."
] | [
"I apologize for the abstract nature of my comparison. I didn't mean to imply that sound waves behave like light, simply that the way a bowl focuses a soundwave is approximately like how a lens focuses light."
] | [
"In both cases, waves are redirected by interaction with things, but I think that's as far as the analogy goes.",
"And that is only as far as I was trying to take the analogy, but seeing the error of my ways I renounce my comparison and will flagellate myself in the name of ",
"/u/horsedickery",
"."
] |
[
"If standing 1 foot away from a cellular tower antenna burns you and causes headaches, why doesn't standing in a city full of thousands of towers have an effect on you?"
] | [
false
] | [deleted] | [
"If you put your hand a centimeter away from a lightbulb, you feel the heat (or might even get burned). Now have a room full of lightbulbs in the ceiling and tables - you don't get burned. You might get some heating over time if the room is small, but that's negligible.",
"It's because there is an inverse square ... | [
"I have never heard of this, and I work in the industry. I am constantly in close proximity to cell towers and have never had headaches or gotten burned or heard of anyone who has. The only thing I could think of that might cause this is if you had a peace of metal on you which was acting as an antenna and heated... | [
"It is all about power density, or watts per square centimeter. Cell towers typically put out a certain number of watts of radio frequency (RF) and do so in all directions. The further from the tower, the less watts of RF per square centimeter. It drops off pretty quickly."
] |
[
"Are LED or compact flourescent bulbs still more cost effective for lighting if you live in a cold environment where you need to heat your home with some source of heat anyway?"
] | [
false
] | Are LED or compact flourescent bulbs still more cost effective for lighting if you live in a cold environment where you need to heat your home with some source of heat anyway? The primary argument against incandescent bulbs as i understand it is that they waste so much electricity as heat not light. But if you are goin... | [
"There has been some similar questions before, like ",
"this",
", ",
"this",
" and ",
"this recent one",
".",
"It all boils down to: Only if you use resistive heating devices like an electric radiator it doesn't matter if you spend electricity on that or something else like lights or appliances. Also ... | [
"How much you feel is not important. The thing is, you can only get two types of energy out of light bulbs: visible light and infrared. The infrared part contributes to heating your house. "
] | [
"The heating cost differential between electricity is about half in favor of gas.",
"Therefore in the winter the led only sabes you half as much because you have to make up for the heat loss with gas heat which is half as expensive as the electricity would have been.",
"No if you were all solar panels with exce... |
[
"What is happening when a fabric gets stained?"
] | [
false
] | null | [
"When a fabric is stained (or intentionally dyed for that matter), molecules which absorb visible wavelengths of light as a result of their electronic structure become attached to the fabric molecules. Usually, the stain is held in the fabric by weaker intermolecular interactions (Van der Waals force, hydrogen bond... | [
"Coincidentally, I just answered a question on ",
"how bleach works",
". It doesn't remove the staining molecules, just destroys the chromophore (part of the molecule which makes it colored). "
] | [
"If you bleach a colored material does this remove the bonded molecules? or simply add others to the mix that cause the fabric to appear white?"
] |
[
"Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"I think this is the right thread for this.",
"I've noticed that when my eyes are exposed to bright light before they adjust I have trouble keeping my eyelids open. However, the total amount of light received seems to matter - I'm able to keep one eye fully open and the other closed with about the same amount of ... | [
"How close are neuroscience and psychology to being combined in the teaching of the mind? They are still taught as separate entities, but we know mental illness comes from chemical/physiological impairments. "
] | [
"Are humans devolving because of advances in modern medicine? Are we circumventing 'survival of the fittest' by keeping people alive through illness and injury?"
] |
[
"Other types of quarks?"
] | [
false
] | null | [
"Up, down, strange, charm, bottom, and top."
] | [
"Can the last 3 do anything?"
] | [
"Yes, but they’re not stable either."
] |
[
"What makes us distinct from other animals?"
] | [
false
] | Sorry for the slightly philosophical question but I am writing an essay on this topic and would like a more scientific answer to this question. To give some background I am using Hans Jonas' 'Tool, Image a Grave' where he argues that that it is our ability to make tools and images and also conceive of death (especially... | [
"Our brain. Specifically our highly developed neocortex. Read the quote below and if you want more answers click on the link and do some searches for \"neocortex\" or \"human brain\" or whatever key words you think will help.",
"From Carl Sagan's \"Dragons of Eden\" found ",
"HERE",
"and clearly the most rec... | [
"From a biological standpoint, we're not very different at all; a lot of our genetic sequence is shared, not just by primates, but other organisms too. Our basic needs are identical, the \"building blocks\" that make us up (proteins, lipids, etc) are all found in one way or another in other species, and even our nu... | [
"The attempt to define what's unique about humans is primarily a philosophical question, rather than a scientific one. Biologically, there are large numbers of things that are unique about humans, just like there are unique features of literally every other species. ",
"Definitions like \"man is the animal that m... |
[
"What does gravity feel like of Europa?"
] | [
false
] | Hello! I was wanting to know what gravity would be like on one of Jupiter's moons, specifically Europa. Would there be a massive tidal effect that takes place doe to Jupiter's massive size? If so how drastic is it? Would the entire moon be shifted towards Jupiter? Would this cause an odd speed for acceleration due to g... | [
"Europa is close enough to Jupiter that it is tidally locked. That is the same side of Europa always faces Jupiter. Also, the moon becomes slightly elongated at its closest approach to Jupiter, and returned to mostly spherical as it moves away from its closest approach. It is thought that this flexing can make a... | [
"The gravity on Europa is 1.315 m/s², or about 13% of Earths gravity. The tidal force on Europa is about 0.00132 m/s² (",
"source",
"), which is about 1/1000th of a decrease, so you wouldn't notice it.",
"On a planets surface, a tidal force is a 'negative gravity' force that is at its maximum on either side ... | [
"Ok this is one of those ask science questions that is fun because it's not to difficult to figure out yourself, given the right tools. To find the force from gravity F = G",
"m/r",
" Where G is the universal gravitational constant, M is the planet's mass, m is the mass of you, and r is your distance from the p... |
[
"Will a hole drilled into a metal block get bigger or smaller when the metal block is frozen?"
] | [
false
] | Let's say you have a 1" cube of steel, and you drill a hole straight through the middle, top to bottom. Now it looks like a bizarre square metal donut. You take that square cube, throw it into the freezer overnight, and take it out in the morning. Would the drill bit no longer fit inside the hole due to the hole's diam... | [
"This is exactly how we attach the turbine disk to the shaft in a T-700 helicopter engine."
] | [
"This is exactly how we attach the turbine disk to the shaft in a T-700 helicopter engine."
] | [
"There's a way to think about this that makes the answer obvious:",
"Suppose instead of drilling the hole you just draw a circle on a face of the cube. When the cube cools down it shrinks. It's pretty obvious that the circle you drew will shrink too.",
"Ok, now imagine you had drilled a hole where that circle i... |
[
"How did organisms in nature evolve to use sequences and angles like the Fibonacci Sequence in their structures?"
] | [
false
] | Inspired by . How did the Nautilus evolve its shell like that? Is there some advantage to it being that shaped? Why are the sunflower thingies spread out in successive 137.5 angles? What evolutionary advantage is there to having structure based on these sequences? | [
"This",
" may be of interest to you. And ",
"this",
" as well. Essentially it seems that the fibonacci pattern arises out of geometry rather than being hard coded into structure."
] | [
"So the Fibonacci sequence produces geometric shapes that require less energy to form? Excellent links and upvoted for that, but that doesn't quite answer my question with regard to animals like the Nautilus. The shell shape I presume would be genetic, so Fibonacci sequence-inspired shells must be selected for, cor... | [
"The important thing to recall is that genes don't code for gross structure, just the proteins which are responsible for constructing it and (abstracted - this is done by other proteins coded for by other genes) the situations in which they should be expressed. In this regard, the material of the shell and the stag... |
[
"Why do cells multiply when they're about to die?"
] | [
false
] | I seem to hear a lot that after the growth stage, cells will still multiply with one of the new splits dying and the other carrying on. Either this is a gross misunderstanding of the process or it was grossly under-explained. So, I guess the first question is why do cells dies anyway? It would seem to me that any reaso... | [
"Just because this is a topic so close to me, I'm going to add an almost useless comment:",
"Stem cell division does not have to be asymmetric --- i.e. one remains a stem cell and one differentiates. It is possible (and indeed often) that the daughters both differentiate or both remain in cycle; the overall balan... | [
"Cells in the body are lost all the time. For instance a significant proportion of your stool is cells from your intestine. These are the cells of the intestinal epithelia. The cells are fully differentiated and do not divide. New cells are developed from areas of the intestine called crypts which contain adult ste... | [
"Interesting stuff. I think the principle model of asymmetric division is the hair follicle. This might be an interesting further reading topic for the OP."
] |
[
"Any news on the attempt to photograph a black hole?"
] | [
false
] | I'm an aspiring astronomer, and I have yet to see any news about it, is there anything I missed? | [
"I'm guessing the OP is talking about the ",
"Event Horizon telescope project",
"."
] | [
"http://www.reddit.com/r/askscience/comments/ori40/scientists_plan_on_taking_the_first_picture_of_a/",
"It's on the front page right now."
] | [
"The Event Horizon imaging project is still very much in the early stages. These things take time. If/when they succeed you'll definitely hear about it. "
] |
[
"Why is string theory empirically untestable? Couldn't we build a microscope powerful enough to see \"strings\"?"
] | [
false
] | null | [
"Imagine you could only measure the shape of a statue by bouncing various sports balls off of it and seeing how they return to you. You could start with basketballs which gives you a kind of pillar shape, as best you can tell. Then baseballs, and you start to see rough features. Then golf balls, then bbs. The small... | [
"I recall that to build an accelerator capable of probing the length scales of strings is on the order of the orbit of pluto. Like we'd have to build a particle accelerator the size of our solar system to be able to \"see\" strings. So in a way, it's empirically testable, just not feasibly so with modern understand... | [
"order of the orbit of pluto",
"That is, with current accelerator technology, I think. If we had more powerful bending magnets, we could theoretically do it with a smaller accelerator.",
"Of course, that doesn't help us right now. The string scale is believed to be many many many many orders of magnitude abov... |
[
"Is it possible to scale/climb under electric fences by simply diverting the current to ground using a rod or conductor of sorts?"
] | [
false
] | I recently watched a documentary on North Korea that followed a guard who defected through the DMZ. In his interview he said that he used a plastic pipe (insulator) to temporarily divert the current to ground by bridging the gap between the wires and dirt with it, following him propping up the low current wires with a ... | [
"It might be more likely that the fence he snuck through simply wasn't energized at the time. North Korea's power grid isn't exactly known for its robustness..."
] | [
"In your example, yes - the guy probably got lucky and did not brush the fence. However, what you are asking might be possible in the right circumstances - it depends on how the fence circuit is constructed. In all likelihood, the fence is a floating DC circuit, meaning it has no electron sink until you touch the w... | [
"Why would current flow to ground through the insulator?",
"I may be missing something, but it seems like he just poked the wire out of the way with something that wouldn't conduct so that he could crawl under without touching it."
] |
[
"Is there any sort of case in which a particle and antiparticle collide which does not result in annihilation for both particles? Can a positive particle survive a collision with an antiparticle?"
] | [
false
] | I just listened to the Radiolab on Symmetry and it raised this question in me. Thank you for your time :D Additionally, is it possible for an electron and positron to collide, resulting in the destruction of the positron, but the electron survives? | [
"Bhabha scattering also has a t-channel where the electron and positron don't annihilate.",
"The more specific example you provided can not happen because it violates a series of conservation laws, mainly charge."
] | [
"By definition vertices on a Feynman diagram describing a process will always have three branches, and as a general rule of thumb the particles going in won't be the same ones coming out. With that said there are some radiation processes which \"preserve\" the parent particle. Famously, electrons do this when they ... | [
"Firstly, the notion of collisions of elementary particles is not obvious. As these behave quantumly, for an interaction between a particle and and an antiparticle, there is only a finite probability of annihilation, that depend on the particles positions, velocities, and collision cross section.\nThere are more co... |
[
"If you used anti-protons in particle therapy, would they behave like protons, electrons, or positrons?"
] | [
false
] | null | [
"They would behave like protons, but they’d also be able to annihilate."
] | [
"Either a positive or negative charge at very high energy will have the same effect: it will knock electrons out of atoms."
] | [
"yeah ok. Thanks"
] |
[
"Do black holes have any 'size'?"
] | [
false
] | I know black holes are very massive and that we don't really know what happens inside them, but I was thinking... Once a black hole 'swallows' something, does that new mass make it bigger and more powerful? Or once a black hole gets started it is always the same no matter how much stuff falls into it? I mean, do the pa... | [
"The main misconception about black holes is that they behave like vacuum cleaners. They don't \"swallow\" things, things fall into them.",
"But yes, black holes increase in mass as things fall in."
] | [
"As far as I'm aware (I'm not up-to-date with theoretical black hole physics, but I have a physics degree!), the black hole itself is usually considered to be a dimensionless object (singularity), that has mass. It therefore has infinite density. ",
"However, there is a distance (the Schwarzschild Radius) from th... | [
"the black hole itself is usually considered to be a dimensionless object (singularity), that has mass.",
"The term \"black hole\" generally refers to the region of space bounded by the event horizon as measured by a far away observer in the asymptotically flat region of spacetime. The thing you're describing is ... |
[
"Can lake Mead ever refill?"
] | [
false
] | Basically the title…are we in a long period of drought or is this the new normal? Is there any realistic amount of rain/snowpack in a wet year that would get the lake back to its 1980s levels? | [
"I like to use dice to explain it to people. If every year the lake loses 35 units of water, but every year you get 10 six-sided dice of input, it'll fluctuate but stay stable. Sometimes you roll a 60, sometimes a 10, but usually between 30 and 40. Climate change takes away dice. With 9 dice, it'll take a long ... | [
"are we in a long period of drought or is this the new normal?",
"More the latter than the former. In terms of us considering this a drought, that's specifically in reference to past climatological means, i.e., there is less precipitation than an average baseline from decades past. Generally, in the context of pe... | [
"Is there any realistic amount of rain/snowpack in a wet year that \nwould get the lake back to its 1980s levels?",
"Note that when the dam was first built (with fewer downstream demands on the water than there are presently), it took it all the way from 1934 to 1941 to fill. Even if everything works the way it w... |
[
"Does black is an actual color or a shadow?"
] | [
false
] | null | [
"Objects do not have color. Color is a psychological, not a physical property. Objects, like you wrote, have surface reflectance properties which determine which wavelengths of light are absorbed/reflected and how they are reflected (e.g. diffuse). ",
"We experience objects as black when our cone receptors are ew... | [
"Wow, this really changed my perspective of viewing everything in this world right now. Thank you so much for explaining it. Does everyone knows this? I mean this is super mind blowing!! To think that every objects do not have color at all!"
] | [
"Colloquially we speak of objects having color and this being a stable property because for the most part, we have similar visual systems. In the same way, most of us agree that the same things taste sweet, but that's because we are detecting sugar and have the same sensors for doing so, not because \"sweetness\" i... |
[
"How does a CME disrupt electricity?"
] | [
false
] | So I just saw a video by a Youtube channel called RealLifeLore talking about Coronal Mass Ejections. And I got curious. He talks about the possible damage and that electricity may be shut down by such an event for years. Why is it lasting such a long time? Wouldn't it only be during the time the ejection actually hits ... | [
"Even though the electromagnetic disruption from a CME is temporary, if it is powerful enough to fry every transformer, computer chip, and electrical switching station in the country, they would all need to be physically replaced, and that would take a much longer time."
] | [
"Plus, even when the Sun emits a big one, it's less than a 1 in 2 billion chance that it will be headed towards Earth.",
"(from the Sun's perspective, the solid angle subtended by the Earth is.. quite small)"
] | [
"Why do you think the utility company gives a dam about it?"
] |
[
"How long would it take for a hand crank generator to fully charge a AA battery?"
] | [
false
] | Obviously there's a couple of variables here, such as crank speed, battery capacity, and so forth. Please feel free to make assumptions on an average use-case. Using this kind of thing; | [
"Most rechargeable chemistry AA batteries have energy capacities of ~2-3 Watt-hours, charge capacities of ~2000 milliamp-hours",
".",
"A healthy person can maintain an output of 75W",
", so recharge could conceivably be done in minutes.",
"However, the real limitation of recharge rate is the internal resist... | [
"Why thank you! Here's to hoping we can get some excellent answers!"
] | [
"I read this and actually said aloud, \"That's an excellent question!\""
] |
[
"What makes the australian black bean - castanospermum australe - poisonous?"
] | [
false
] | Wikipedia didn't specify what chemical actually made it poisonous, and several other links also didn't specify it. | [
"Well you might figure this, but Castanospermum contains at least one toxic substance and it's called castanospermine (heh). I'm unsure whether there are more toxic substances. ",
"Castanospermine is a glucosidase inhibitor. I could explain to you what that means if you're really interested but that's a whole ot... | [
"There might be very little difference.",
"\nCastanospermine has been reported to have an anti-diabetic effect, and it has long been noticed that a lot of alkaloid plants actually have an anti-diabetic effect. This might be the main cause. ",
"Interestingly, compare the chemical structure of ",
"castanosperm... | [
"That sounded familiar so I googled it, and found that anti-diabetic drugs are alpha glucosidase inhibitors. So I'm interested in knowing how it's different from that"
] |
[
"Are there any major advantages to flapping wings, or are fixed wing aircraft something we have truly improved upon nature? Given advanced enough materials and power supply, could ornithopters theoretically be practical compared to fixed wing and rotor craft?"
] | [
false
] | null | [
"Short of a propulsion system powered by explosive flatulence, our aircraft design, while very efficient, is simply impractical for animals. In the same way, cars with wheels are more efficient than limbs but a living organism can't support a wheel. Our machinery is certainly simpler and requires less energy but is... | [
"This actually depends on the size of the flier.",
"For a large wingspan, non-flapping will always be better. This is because large units of air have less \"surface tension,\" behaving more like what you think about when you envision your own arms flapping.",
"At smaller distances, the surface tension of air i... | [
"Air does not have surface tension, nor anything of the like. Flapping wing flight is governed by relative frequency and relative velocity.",
"Insects are far less efficient than birds, although their small size does allow them to hover, making use of dynamic stall and wake recapture.",
"Telling someone interes... |
[
"All all rechargeable battery chemistries inherently degrading, or are there technologies either practical or theoretical that would allow for rechargeable batteries that barring mistreatment keep the same capacity?"
] | [
false
] | null | [
"There are lots of Electrical energy storages devices that do not degrade with direct usage. Their issue is that they either are very expensive, or have limited power to weight or volume.",
"Flywheel energy storage. Used everywhere, ultra robust. Problem? Cost and minimum size required.",
"Flow Batteries.... | [
"There are advancements being made in this area. Personally, I believe we are on the verge of a rechargeable battery that will keep the same capacity almost in definitely. Here’s an interesting read on one such technology. ",
"SOURCE"
] | [
"For large-scale installations, there are already flow batteries (",
"https://en.wikipedia.org/wiki/Flow_battery",
") which would qualify, but I think you're more likely thinking about smaller, consumer-grade and sized batteries. There are thin-film lithium-ion batteries under development which have shown no de... |
[
"How much physical space is needed to store the data of every possible game of chess?"
] | [
false
] | And also what is an informed estimate of the total amount of info/data our universe holds. IE if you were to model every atom. it's location etc, store all of it as a binary number, how many orders of magnitude greater would it be than total chess game permutations (which I hear is c. 10 | [
"Yes, well I don't think it would be possible given the total number of atoms in the observable universe.",
"The total number of chess permutations is indeed 10",
" according to the paper 1950 ",
"Programming a Computer for Playing Chess",
" and is known as the Shannon number.",
"The ",
"number of atoms... | [
"The reason we consider only the observable universe as the universe we can interact with is not just semantics. If you imagine your actions as being on a world line and possible interactions in a light cone, then there are certain things outside of that light cone. Given the expansion of the universe there are reg... | [
"endlessly produce new matter ",
"I don't know of any good evidence for this. This seems like a speculative idea not rooted in solid evidence."
] |
[
"Why doesn't frequency affect current in the photoelectric effect?"
] | [
false
] | [deleted] | [
"If electrons are discharged with greater energy, doesn't that mean they move faster and the current should be faster?",
"So I see where you are coming from. Let's talk a bit about the experiment to shed some light on this.",
"We have two plates of metal as part of an electrical circuit. When we apply a voltage... | [
"is increasing amplitude pretty much the same as increasing the intensity?",
"Not really.",
"The thing is amplitude doesn't really have a nice analogue in light. Photons aren't really little wave packets, you could talk about the strength of the electric field of a photon but that isn't simply defined.",
"I p... | [
"is increasing amplitude pretty much the same as increasing the intensity?",
"Not really.",
"The thing is amplitude doesn't really have a nice analogue in light. Photons aren't really little wave packets, you could talk about the strength of the electric field of a photon but that isn't simply defined.",
"I p... |
[
"If I spill my coffee onto a piece of paper, what determines the rate at which the fluid advances through the paper?"
] | [
false
] | [deleted] | [
"Sounds possible, but I suspect he would see the slowing down even with an infinite pool. In doing ",
"thin layer chromatography",
", I have noticed that the rate at which my solvent front advances up the plate slows down as it gets farther up the plate. In that case I don't have an ",
" pool of solvent, bu... | [
"To me that argues against it being a vapor pressure based phenomenon. The vapor pressure of water is pretty low, I wouldn't worry about losing it to atmosphere and if you're doing your TLC in a closed jar that should negate any vapor pressure effects."
] | [
"Do you mean a thin strip? The amount of liquid is still constant and finite. The adhesive property of the paper is going to have to pull more and more water as the area of saturation gets larger and eventually it is going to be overpowered by the cohesiveness of the water. It isn't just pulling the water at the \"... |
[
"Despite the diversity of life, no form has three sexes. Why exactly?"
] | [
false
] | null | [
"I took a class on the evolution of reproduction. We actually do see multiple sexes (mating types) in certain species like Physarium (a genus of slime mould) which has >500 sexes (but it still only takes two individuals, who are not the same sex, to make a baby).",
"The main problem that limits most species to 2 ... | [
"Ah, I heard someone talk about this on a podcast the other day and it made alot of sense. So, while I can't say \"it's definitely because of X\", here is some food for thought.",
"With the two sexes we have, the male is gametes are very small, they basically just contribute some genomic DNA. The female gamete is... | [
"Not a biologist, but I do remember reading about this question year ago. My understanding is as follows:",
"The main reward for sex is sharing of genetic information. Species that reproduce asexually evolve much more slowly and have troubles adapting to new environments.",
"Adding a third (or fourth) sex would... |
[
"Do Turbo Engines have more cylinder pressure than NA engines?"
] | [
false
] | Background: Friend says turbo engines (typically) run lower than naturally aspirated engines, and concluded turbocharged engines don't require as high of octane as an NA engine of the same compression ratio. From my experience with ECU tuning, I know that maximum Manifold Absoulute pressure is often (roughly) double in... | [
"Your friend is right and then wrong.",
"Yes, turbocharged engines usually have lower static compression ratio. For example my Subaru had 8.5:1. While NA engine is typically 11 to 13. But why ?",
"To compensate for higher air pressure from turbocharger. To make more force you need more pressure that comes from ... | [
"The primary reason for lower compression ratios on engines with forced induction is that the compression process (from turbocharger or supercharger) heats up the air, and even with an intercooler, the increased temperatures raise the risk of pre-ignition (or detonation, or knock). Higher octane increases the auto ... | [
"great response, thank you"
] |
[
"Is there any scientific evidence or reason that you gain weight by eating late?"
] | [
false
] | I almost exclusively eat late, ranging anywhere from 9pm to 11pm. I just need to be relaxed and have time to enjoy eating. When my kids are awake I have to be alert and take care of them,so I don't eat just a few bites with them and prepare dinner after they are asleep. People who know about of this habit tend to state... | [
"Directly - no. Calories are calories and whether you eat late or early doesn't seem to change much in terms of nutrients.",
"However, there has been research that suggests that people who eat late tend to ingest more calories:",
"https://pubmed.ncbi.nlm.nih.gov/25439026/",
"There is also evidence that people... | [
"Interestingly, it seems that hormonally there is an urge created to eat more the more tired you are:",
"Huh, don't you get tired when you are really hungry too? I wonder if it's your body getting them confused"
] | [
"When you're tired your body tells you to sit, eat and relax.",
"When you eat a lot your body tells you to sit, relax and digest."
] |
[
"If gravity affects time, can time affect gravity?"
] | [
false
] | Layman science fiction nerd here, please be gentle. I've read that in places where there's lots of gravity, time is affected (speeds up? can't remember) My question is this: In a theoretical situation where excessive time is produced, is gravity affected? If so, how, what are the parameters, does more time give more or... | [
"General Relativity says that time passes more slowly in a gravity well.",
"In a theoretical situation where excessive time is produced, is gravity affected?",
"Since time isn't really 'produced' by anything, there's no way for something like this to happen."
] | [
"In a theoretical situation where excessive time is produced",
"It's hard to answer your question, as I have no idea what this means."
] | [
"Wait, time slows down with excess gravity? As in, we age less on Earth than in empty space? I thought it was the opposite."
] |
[
"Would it be ecologically feasible to reintroduce cheetahs into the western US?"
] | [
false
] | null | [
"Could it be done? Yes it's quite possible if there were a proper prey item available. Should it be done? No"
] | [
"proper prey item",
"Jackrabbits.",
"Also: The theory is that the reason ",
"pronghorns",
" are so fast is that they used to be the chief prey item for the North American Cheetah. ",
"(Pronghorns aren't real common now, but if we got real gung-ho on the cheetah re-introduction program, we'd probably want... | [
"Oh, I had been under the impression they were related to old world cheetahs. Thanks.",
"Also they have been extinct for only about 10,000 years actually, from what I have read."
] |
[
"What determined the earths final orbit position and how did it begin its orbit as opposed to just moving closer to the sun?"
] | [
false
] | I have read explanations as to the reason why we are not pulled into the sun as we are in orbit moving sideways around the sun. Many websites have used the analogy of swinging around a ball on a string as an example. What isint clear is how did the earth first enter into the correct distance that its orbit now inhabits... | [
"The 'correct'ness of orbiting bodies is basically self-generating. Bodies without 'correct' orbits (those that are too slow or to fast etc and so are less circular) collide with the Sun or some other body, or are flung out into deep space. After billions of years, everything thats left looks nice and planned, but ... | [
"Do you mean Earth's ",
" orbit? Because simulations show that the planets are not in stable orbits, long term, and wander in and out quite a bit. The Earth will still be wandering when the sun swells to red giant state and either evaporates it all away or slows it down by friction and swallows it completely."
... | [
"The reason the earth did not initially fall straight into the sun is conversation of angular momentum - things that are spinning need to keep spinning (unless acted on by an outside torque). In this case the \"spin\" in question is the tangential velocity of the earth relative to the sun.",
"With slightly more m... |
[
"Why is proving Riemann so important?"
] | [
false
] | According to "The Math Book," (by Clifford a Pickover) proving the Riemann Hypothesis is the most important open question in mathematics. Say a mathematician did it tomorrow...what would the implications be? What use would come from it and how would we seeit manifested in quantum theory, or in our day-to-day lives? | [
"Here",
" is a list of some important consequences of the Riemann hypothesis. As you can see, they are mostly mathematical in nature. You would not see it immediately manifest in your day to day lives, as is the case with just about any mathematical research being done nowadays. I'm also not aware of any implicat... | [
"A practical thing that might effect the everyday world would be credit card security which uses primes to create a very difficult security systems. It's difficult because primes are still very mysterious to us and how it is distributed. The Riemann hypothesis, from what I understand is that it suggests that all pr... | [
"I'm also not aware of any implications in Quantum mechanics.",
"http://en.wikipedia.org/wiki/Hilbert%E2%80%93P%C3%B3lya_conjecture#Possible_connection_with_quantum_mechanics",
"Searching for Riemann hypothesis and quantum mechanics turns up multiple papers."
] |
[
"In 4 - vector space-time geometry, why is the time component negative?"
] | [
false
] | null | [
"For background on the OP's question, see ",
"this",
" post from earlier today. The question is: in spacetime, vectors have four components (one for time and three for space). The length of a 4-vector (the technical name for these) with components (t, x, y, z) is defined as",
"length",
" = -c",
" t",
" ... | [
"One way to look at it: ",
"Space is \"circular.\" If you want to draw a line connecting all the points that are equidistant from one center point... you draw a circle. (or sphere in 3-D)",
"Space-Time, on the other hand, is \"hyperbolic.\" To draw all the points equidistant from one \"event\" (a location in sp... | [
"If (ct)",
" is greater than x",
"+y",
"+z",
" your length takes on a complex value; I assume this would be the case for a particle moving faster than c. He's asking how one should interpret the imaginary part of that complex length.",
"And if I've misinterpreted and that ",
" what he meant, then I woul... |
[
"If visible photons are absorbed by atoms and then re-emmited at the same wavelength, why can light not pass through dense matter?"
] | [
false
] | For example, if you shine a light on a concrete block which appears grey, why don't photons travel through the block by this re-emmission of absorbed photons? | [
"Light traveling through materials scatters. This includes air, water, glass and opaque materials. When it scatters, it is not necessarily re-emitted at the same wave length, or in the same direction. The particle that absorbed the photon may de-excite by emitting two photons with lower energies than the original. ... | [
"Light can pass through dense matter. It's just a matter of how likely it is for each photon to get through unscattered and unabsorbed. As a photon passes through just about anything besides vacuum, there is a finite chance that it will be scattered (direction changed) and/or absorbed. The thicker the material, the... | [
"Adding a bit more to this to more fully answer the quesiton:",
"When light is absorbed by a substance, only light of specific wavelengths is absorbed and only light of specific wavelengths is reemitted. The rest is scattered. For a block of concrete, visible light is scattered rather than absorbed while infrar... |
[
"Obviously, there are solids that float in liquids. Are there liquids that float in gases (specifically air)? Solids in air?"
] | [
false
] | null | [
"In a practical sense, I'm not aware of any liquids light enough or gases heavy enough to allow this to happen. If you take one of the densest gases, radon, its density is something on the order of 10 g/L, and if you take a very light liquid, say an alcohol, they have densities on the order of ",
" g/L. This is a... | [
"When densities of these solids are given it is as if they are in a vacuum. Aerogels are extremely porous, which gives them their low density. In a radon atmosphere the pores would fill with radon gas and as radon gas + aerogel is heavier than radon gas alone the aerogel would sink.",
"I am a material chemist hav... | [
"That boat only works because there is air inside it. If that video is an example of a \"solid floating in gas\", then so is a hot air balloon."
] |
[
"Why are things that aren't fission products themselves, become \"radioactive\" and are dangerous? (IE Clothes, metal, etc)"
] | [
false
] | null | [
"They are contaminated. If you’re in an environment where there’s radioactivity dissolved in the water, in the dirt, in the form of dust in the air, etc., you will carry that contamination with you."
] | [
"Well what makes them contaminated? Fission makes things radioactive, the things contaminated have simply just been around it and effected by it. What makes it continue to resonate radioactivity?"
] | [
"They have collected radioactive dirt, water, and dust, in and on their bodies and clothes, and inadvertently carried it with them."
] |
[
"Why do human males have external penises, rather than penises that only come out for copulation?"
] | [
false
] | It seems that for most animals, penises only emerge during sexual arousal. Why are humans different? Is it a feature we share with other primates? | [
"Yes, it is a feature we share with other primates in a sense. The reason for it is likely both physiological and social. ",
"Primates have an amazing diversity when it comes to penile morphology. There have been entire books written on it. Most have a penile spine called a baculum that assists copulation. This... | [
"Questions like this are incredibly difficult to answer experimentally, so most potential explanations will rely on post-hoc rationalization - in other words, trying to fit the data into your explanation rather than the other way around.",
"I can think of a number of potential explanations, but these would merely... | [
"Here's a little gallery of primate penises I just found for some morphology comparison.",
"Chimpanzee",
" | ",
"Bonobo",
"\n| ",
"Orangutan",
" \n| ",
"Proboscis monkey",
"\n| ",
"Vervet monkey",
"\n| ",
"unknown species",
"\n| ",
"unknown species",
"\n| ",
"unknown species, surly exp... |
[
"When they say the most common cause of death among children is accidents, do they mean car accidents only or any unintentional action that causes death (chocking by food or sh) ?"
] | [
false
] | null | [
"Who is “they”? Unless you present a source no one can answer accurately."
] | [
"Oh sorry for that, i was reading on amboss a resource for medical students about leading cause of deatg in children aged from 1-18, and they say that leading cause of death is accidents and don't elaborate which ones."
] | [
"In the US it’s firearms as of the last 2 years, so you need to give details on the source"
] |
[
"What makes spinal cord tissue different than other tissue than can repair itself when damaged?"
] | [
false
] | null | [
"I'm not entirely sure what the context of your question here is, but I will assume you are asking why spinal injuries can cause permenant damage and disability.",
"The answer is that nerves do not repair. The nerves you have when born are largely going to be the same nerves you have when you die. This is for sev... | [
"The central nervous system is composed of both the brain and spinal cord and contains cells called \"neurons\" that are used to transmit the electrical information we perceive as thoughts and senses. These neurons transmit information via the use of long extensions of the cell body called axons that are frequently... | [
"That and also the fact that the spinal cord is like a mega cable, made up of thousands and thousands of smaller cables, for a full recovery every severed cable needs to find its second (severed) part, and this is usually impossible, although theoretically possible, the factors are listed above. Extra fact the neur... |
[
"Why do sneezes often come in pairs?"
] | [
false
] | null | [
"I've asked many different boards so far and this is the first time anyone's even responded. I guess I'm making progress!"
] | [
"Sorry that your best response is essentially: insufficient data. I'd be quite surprised if anyone's come across a truly explanatory theory as to why this is the case. First I'd say that I personally experience the classic double-sneeze, however, I've encountered many people that get any number of sneezes each bo... | [
"I call bullshit on anyone who even attempts this one."
] |
[
"Could FTL neutrinos be used for extraterrestrial communication?"
] | [
false
] | [deleted] | [
"So I'm not a particle physicist, but I do know that neutrinos are so small they rarely interact with larger matter like atoms. A hundred billion neutrinos are streaming through every square centimeter of the Earth every second, only one of which will interact with something (",
"source",
"), but it takes a hug... | [
"Even accepting assumptions 1 & 2, there may be some issue with 3&4. ",
"In the paper about the Opera experiment (",
"http://arxiv.org/abs/1109.4897",
"), they looked into energy effects on neutrino speed a little, analysing both the entire event history, as well as sub-dividing it into \"low\" and \"high\" e... | [
"I am a particle physicist, and I approve this message.",
"Actually, the OPERA experiment gives you an idea about what you would need to do in order to transmit a message, based on our current understanding of neutrinos. A neutrino beam from CERN is being shot at the OPERA detector in Italy with a certain timing ... |
[
"Does scratching at irritations like bug bites harm or delay the healing process at all?"
] | [
false
] | null | [
"It will cause more histamine release and more immune cells to infiltrate the area, causing more irritation. Theoretically it might have the potential to fight against certain microbes, but in terms of healing, it would not help. ",
"First of all, the scratching causes more damage to the area. Then the immune cel... | [
"It's important to keep in mind that not everything has an evolutionary advantage simply because it is a trait that evolved. "
] | [
"Why then have we developed such an intense, hard-to-resist itch response? Animals often will scratch themselves to the point of skin loss and infection, which seems like a very bad trait for survival.",
"I can understand a slight itch response to dislodge an insect or object, but beyond that, what benefit does a... |
[
"Is there anything “special” about the visible spectrum?"
] | [
false
] | Our eyes perceive light in the visible spectrum, which is just one small part of the full electromagnetic spectrum. We can differentiate hundreds of colors out of this relatively narrow spectrum of light. My question is, is there anything special about the part of the EM spectrum that our eyes can see that allow us to ... | [
"Hi, I'm a astrophysicist.",
"There's absolutely nothing special about visible light in principle. Our sun emits light ",
"fairly predictably across IR, visible, and UV",
" (although it also emits in other wavelengths). We can only see a tiny fraction of that spectrum",
"citation needed]).",
"However, our... | [
"The differentiation between colors is also an artifact of our biology. We have three types of cones that are sensitive to red, green, and blue respectively (roughly, they all have an absorption spectrum). A human that sees UV light is just seeing blue because that's the only cone that gets any signal. If we had mo... | [
"Geosciences here. To go along with this, the Earth’s atmosphere has what we call atmospheric windows, which are wavelengths of the EMS that can pass through. The visible spectrum passes through at a high rate while much of the spectrum does not."
] |
[
"Can you identify which forest ash came from by analyzing the ash?"
] | [
false
] | With the California Bay Area currently being covered in ash from wildfires across the state, I am wondering if you could analyze the ash that is falling on the ground here and determine which forest it came from. If not, what, if any, information could you determine? Thank you! | [
"Generally I would say no.",
"In specific cases yes. For example, if the soil in a particular forest is enriched in, say, the elements selenium and vanadium, you might be able to assert that this particular ash sample possibly came from that forest. ",
"In a court of law, IMO, a SME for the other side would shr... | [
"I could see if different trees put out different compositions of ash you might be able to say what sort of tree it came from, and that might help you differentiate the source. A coworker did a project where they put wood smoke through a mass spec and demonstrated they could figure out what species it was from, so ... | [
"That’s a surprising finding! Thanks..."
] |
[
"Why does alcohol interact with so many other drugs?"
] | [
false
] | A lot of drugs carry a warning to not mix with alcohol. Is it just because it's legal and widely used or is there a chemical explanation? | [
"Oh wow, lots of misinformation in this thread. Yes, alcohol has CNS effects. Yes, it affects other organ systems. But ",
". The source of its interaction is its metabolic pathway.",
"Alcohol is oxidized in the liver, primarily by the enzyme Alcohol Dehydrogenase. However it is also oxidized by the cytochrome P... | [
"and humans have used it for so long, our bodies have numerous adaptations to its consumption",
"Really? So does this mean I have a higher alcohol tolerance than someone from several hundred (thousand?) years ago, despite never having had a drink? Or that mean we now just metabolize it faster and don't stay drunk... | [
"and humans have used it for so long, our bodies have numerous adaptations to its consumption",
"Really? So does this mean I have a higher alcohol tolerance than someone from several hundred (thousand?) years ago, despite never having had a drink? Or that mean we now just metabolize it faster and don't stay drunk... |
[
"How does a plant seed know which way is \"up\"?"
] | [
false
] | I guess since they are buried deep in the ground with no sunlight or without any other way of knowing which way it should grow to get the surface. | [
"I believe seeds have the ability to detect the directing of gravity (gravitropism), but they can also detect temperature gradients and hence direction to the surface."
] | [
"A bunch of other commenters have mentioned that plants can sense gravity, but nobody's explained how! The answer is that they have starchy components (amyloplasts) in some of their cells that are heavier than the cytoplasm, making them sediment at the bottom of the cell. A hormonal growth signal then emanates in t... | [
"If I were a smartass, I'd talk about how the vacuum of space does no one favours.",
"More seriously, yes! We have been experimenting with plant growth in space in both shuttles and on the ISS since the 80s. Root formation is described as 'disorderly' or 'random', because they have no \"down\" to aim for.",
"Th... |
[
"Why do we need a Higgs boson to impart mass to particles?"
] | [
false
] | Isn't mass just energy? Or does energy not interact with gravitational fields in the right way? How then could a Higgs particle have a ridiculous energy of 250 GeV (one possibility that hasn't yet been ruled out) if it gives itself mass? | [
"So there are these things called ",
" What they are and now they work aren't important right now; just know that they're a thing.",
"Four elementary bosons have been conclusively identified. There's the photon, which is the boson of the electromagnetic field. Then there are the W and Z bosons, which are relate... | [
"I forgot about photons, and that by mass one might mean the m2 = E2 - p2 variety (in c = 1 units because that's how I learned it).",
"What? No. That's completely wrong. Photons are ",
" and mass is independent of momentum.",
"So the Higgs boson is basically a necessity of QFT",
"No, it's part of the Standa... | [
"It's bad science reporting. It's like the kid who sulks because he's looked everywhere for his toy, even though he really spent three seconds glancing around his room before having a pout."
] |
[
"How can light sails exist if \"light\" has a nonzero mass?"
] | [
false
] | null | [
"This is an ",
"FAQ"
] | [
"Not necessarily, I'm specifically wondering if there is a proof that the mass is 100% zero as opposed to as absurdly close to zero as possible.",
"I realize this question basically questions the whole basis of the current energy without mass formula. ",
"My only current proof that the mass is not one katrillio... | [
"Oh I misread the question, I read it as \"how can light sails exist if light has no mass?\".",
"Why would light having mass mean a light sail couldn't exist?",
"People have done experiments looking for a photon mass. You can only ever put an upper bound on the photon mass but it is currently something like 10"... |
[
"Electromagnetic radiation; can electronics actually give you cancer or headaches, or render you impotent, as some people claim?"
] | [
false
] | As an engineer, I find it frustrating that some people genuinely believe that household electronics can do collateral harm. "Bad waves" from televisions can give you cancer, a cellphone in your pocket can make you infertile. But then again, I can't seem to find solid proof that they are indeed, completely safe. Is ther... | [
"I tried digging around. The answer appears to either be no, inconclusive or conflicting. Now I'm confused, too!",
"Here's one short paper from ",
"John Hopkins University on cell phones",
" (pdf file)",
"WHO says ",
"EM fields possibly carcinogenic",
". Says inadequate to draw conclusion.",
"Here's o... | [
"Let's do some theory to tackle the idea. ",
"Electromagnetic waves are photons. The only way photons could interact with your body are either exciting the electronic state of a bond in your biochemical makeup (like UV tanning --> skin cancer), or by triggering some resonant frequency in your molecules/cells (lik... | [
"I don't think microwaves use a resonance phenomenon for heating. How I have always understood it is that the water molecules, a dielectric, aligns (rotates) to the electric field in the micowave oven. This dipole rotation has a region between where subjected electric field oscillations are \"oscillating slow, with... |
[
"Is the ionic radius of Cu2+ bigger than Cu as an atom? If so then why?"
] | [
false
] | I could not find any help on the internet. Any help would be very much appreciated :) | [
"No, Cu2+ has fewer electrons than Cu. Whenever electrons are removed from an atom its radius gets smaller. This happens because electrons push against each other so as electrons are removed the outer ones can move closer. If you want to think about orbitals, Cu has an electron in the 4s1 orbital and Cu2+ does not.... | [
"thanks a lot. I guess there was an error in my school exam ;)"
] | [
"Cu2+ as an ionic radius of 0.73 angstrom, Cu has an atomic radius of 1.3 angstrom.",
"Cu has more electrons orbiting it, in order to relieve high energy electron interaction effects the electrons orbiting Cu expand the orbital, increasing the atomic radius.",
"Cu2+ has less electrons orbiting it, less electron... |
[
"Is time infinitely divisible, or is there a minimum quantum value for time?"
] | [
false
] | I suppose the same question can apply to space. Matter and energy have minimum quantum values, and matter/energy warp spacetime around them, so it would seem natural to assume that spacetime would also have some kind of minimum divisible amount, but at the same time that would seem to suggest that existence is digital ... | [
"Energy does not have a minimum quantum value. When you measure the energy of a particular quantum system, the energy that you measure can only be particular values. These values are different for different systems, and there is no universal energy 'quanta' which all energy eigenvalues are multiples of.",
"The sa... | [
"FYI, it's very straightforward to define and use smaller intervals of time than the Planck time -- just divide it by any number! Super easy. :) The Planck time isn't necessarily \"special\" -- it's just a natural unit for time in Planck units.",
"The Planck time ",
" be the smallest ",
" interval of time ... | [
"FYI, it's very straightforward to define and use smaller intervals of time than the Planck time -- just divide it by any number! Super easy. :) The Planck time isn't necessarily \"special\" -- it's just a natural unit for time in Planck units.",
"The Planck time ",
" be the smallest ",
" interval of time ... |
[
"What is the nutritional content of human flesh?"
] | [
false
] | Hypothetically if someone were to substitute human flesh instead of meat along with a balanced diet, how would it impact on their health? Positives? Negatives? | [
"In the amazing though somewhat academic work, \"Dinner with a Cannibal.\" The author discusses the survivors of a plane crash in Chile(?) who were forced to turn to cannibalism to survive. Essentially, the human body provided all the nutrients they needed to live (high in fat and protein) however they began to hav... | [
"Well, ",
"the person who commented on \"tastes like pig\" may be right.",
" Because of the amount of salt we take in with our daily diets, and the similarities between people and swine (we can even substitute organs), I'm not surprised human meat is compared to pork. ",
"That being said, the biggest negati... | [
"From what I understood of that, it's only transmitted through the consumption of brain matter, something to do with a protein only found there.",
"(edit: what greath was saying below)"
] |
[
"Can I propose a solution to the non-contributors that post to askscience?"
] | [
false
] | null | [
"Hmmm... that's putting a lot of trust in the moderators, and I've seen one or two lame posts by the mods themselves. What's the benefit, though? If someone posts crap, they get downvoted to hell and/or deleted."
] | [
"What's the benefit, though? If someone posts crap, they get downvoted to hell and/or deleted. ",
"It would remind people to make insightful posts. I'm definitely for this, good idea OP."
] | [
"It would remind people to make insightful posts",
"Why? Isn't that what upvoting is supposed to do? Will I get brownie points whenever I make an insightful post?"
] |
[
"If energy can be never be created or destroyed, and as the universe is expanding, would there come a time where all energy is so dissipated that things have little to no, energy and hence would freeze?"
] | [
false
] | null | [
"There are no (nontrivial) global conservation laws for energy in GR. There are some spacetimes in which conservation laws can hold, but there is no law that holds for all spacetimes. That is, the statement that \"energy cannot be created or destroyed\" is not necessarily true in GR. Indeed, energy conservation typ... | [
"Yea, the eventual heat death of the universe.",
"\n",
"From this article",
": \"Every star will die, nearly all matter will decay, and eventually all that will be left is a sparse soup of particles and radiation. Even the energy of that soup will be sapped away over time by the expansion of the universe, lea... | [
"There is a great short story by Isaac Asimov that is related to this: The Last Question (",
"http://www.multivax.com/last_question.html",
")"
] |
[
"What could have emitted the \"Oh-My-God\" particle (a likely proton caught traveling with 99.99999999999999999999951% of the speed of light?"
] | [
false
] | The doesn't mention its origin. | [
"Well, the short answer is that we don't know, but analysis of the most energetic cosmic rays shows that a lot of them originate in one part of the sky (see ",
"here",
") at least hinting at the location of the source. Now the Ice Cube neutrino detector under the South Pole is starting to see super-high energy... | [
"Particles shouldn't go that fast for too long. The ",
"GZK",
" limit sets a suggests a threshold before the speed of the cosmic ray is great enough to blue-shift the Cosmic Microwave Background (",
"CMB",
") to high enough energy in the frame of the cosmic ray to slow the cosmic ray down. This only holds o... | [
"What is the long answer?"
] |
[
"Where does the light come from during a nuclear explosion?"
] | [
false
] | I know a lot of the bright light associated with a nuclear explosion (like a nuclear weapon going off) must be associated with the fire. However, would a nuclear weapon give of light in, say a vacuum, where there was no fuel for fire? | [
"I know a lot of the bright light associated with a nuclear explosion (like a nuclear weapon going off) must be associated with the fire.",
"Why do you assume light is associated with fire? What about chemiluminescence (e.g. glow sticks) or glow-in-the-dark materials? What about fireflies or lightbulbs? Why ex... | [
"Visible light is the result of electrons moving from an exited state to a ground state, the energy between the two states being given off as a photon. In the case of a nuclear reaction, the energy needed to move an electron to its excited state is provided by the nuclear reaction. These excited electrons then give... | [
"Building off of what radaroffline and Yuforic said:",
"A nuclear explosion provides immense amounts of energy (in many forms like blast, multiple forms of radiation, heat, etc.) through fission/fusion reactions (depending on the nuclear weapon). That energy transfers to electrons in an electron shell and causes ... |
[
"Why don't step up transformers violate the law of conservation of energy?"
] | [
false
] | null | [
"V = IR applies to Ohmic circuit elements, where there's a linear relationship between the voltage and current.",
"V = IR does not apply ",
" the insulating gap of a transformer, and there's no need for any resistance to change for the transformer to function.",
"How can it possibly self-limit it's own curren... | [
"I get that, I'm not taking about the insulating gap. I'm talking about the circuit on the other side of the transformer, the circuit that the secondary coil powers. I and V in that circuit are connected. How can you have a high voltage but a very low current without introducing resistive elements into that circuit... | [
"I'm talking about the circuit on the other side of the transformer, the circuit that the secondary coil powers.",
"Then what is the resistance you're referring to? Is ",
"this",
" the question you're asking?"
] |
[
"How can I calculate the power output of a Fresnel reflector/Parabolic concentrator"
] | [
false
] | I'm currently working on a project for my engineering degree and am struggling with calculating outputs for a solar oven. I mainly want to focus on viability within the UK and am unsure what to use as a Q value (for the amount of energy provided by the sun) within my Stefan-Boltzmann equation. I've seen the average pro... | [
"The amount of solar energy that you have to work with is going to be in the form of Watts per square meter - energy per area per time. The area in this case is the area of your reflectors - this is your maximum starting value. That energy is then concentrated into a smaller space ... but the amount of theoretica... | [
"I'm still not sure that I'm following you correctly. ",
"For peak values in a particular spot, you're either going to have to measure yourself, or find measurements that someone else has taken. I don't know of a way around that. ",
"For the ... diffusivity affecting things - if you're worried about the radi... | [
"Sorry, I should have stated I meant 1000W/m",
" is the output of the sun on average, which goes down to 600W/m",
" in the UK (assuming the midday sunshine) so if for example the surface area of my reflector was 1m",
" what would be the energy output. I'm aware I'll change this through emissivity (for alumini... |
[
"Why would the addition of a yellow subpixel to the usual RGB increase the picture quality if the input remains the same?"
] | [
false
] | I mean, if the signal coming into the TV with the extra suibpixel is the same RGB signal that would be displayed on your typical RGB TV then where would the extra colorspace information come from? Wouldn't an RGB monitor by default offer the best possible picture, ie a 1:1 representation of the incoming RGB signal wit... | [
"There is no extra colorspace information. These televisions do some onboard signal processing to derive or augment a yellow channel, and that's about it."
] | [
"The theory is that the color mixtures that produce yellow aren't precise enough. To get yellow (and other non primary colors), we are essentially mixing RG. The RGB signal might be (128)(128)(0) to get a dark mustardy yellow. The TV that had RGB(Y) would interpret that signal as (0)(0)(0)(128). Add in some in... | [
"If there was perfect RGB fidelity, then it shouldn't help.",
"But it is possible that it can help augment the imperfect output of the other three pixel colors."
] |
[
"Why are creases in paper impossible to smooth out?"
] | [
false
] | What about the material of paper makes that so difficult compared to, say, a folded cloth? | [
"This image",
" shows the difference in a fold in paper (top left) and polyester fabric (bottom right). As you can see, the polyester fibers bend and deform, but are not damaged and can therefore be smoothed out. They are also woven together, so individual fibers won't be separated from the cloth. Cellulose fiber... | [
"They're from ",
"this paper",
" about origami robots, but I just found it on Google."
] | [
"where did you find those images? they're amazing"
] |
[
"What is the scientific/ biological explanation behind female menstrual cycles syncing?"
] | [
false
] | null | [
"Menstrual synchrony seems to be just plain chance, as far as I know. Menstrual cycles of women greatly vary, and supposed synchrony is usually noticed with a wide range. Given a group of women whose cycles can have a difference of two weeks, and which last only a few days to over a week, they'll eventually occur a... | [
"To add to this, the mechanism often proposed is that it's due to pheromones. The problem is that there's no evidence that humans use pheromones. The vomeronasal organ, which in other species is used to detect pheromones, is either non-existent or inactive in human beings. So even if we did send out pheromones, we ... | [
"It's now thought to be mostly a myth. Because most (but not all) menstrual cycles are 28 - 35 days (that will vary person - person and even within the same person) and last ~5-7 days (again, SO much variation there) if you have a large enough group of women, at some point they'll overlap. "
] |
[
"How possible is it to access oil and natural gas fields by drilling from a place lying hundred kilometres away from the field?"
] | [
false
] | Is it scientifically possible that Iran can access oil fields of Saudi Arabia or that Turkey, Kazakhstan access Russian oil fields by drilling horizontally? Moreover, can they transport oil this way and can it be detected by the other country? This picture illustrates what I mean | [
"That article should give you your answer. The lengths mentioned are apparently our current maximum lengths. Even if you double the longest mentioned one, it wouldn't be very far relative to the \"hundreds\" of km from your question."
] | [
"Thank you for your reply. Actually bend drilling at right angle is of minor if of any importance. ",
"I'm more interested in if it actually possible to access oil fields lying hundreds of kilometres away from a place you start drilling. ",
"edit: here is something I found after a short research on the Internet... | [
"Unlikely to happen as you've drawn, since how would they bend the drill bit at the right angle?",
"However, they can certainly ",
"drill diagonally and drillholes do not have to be straight",
"."
] |
[
"If our internal organs only contain pain receptors, why is it that when I eat/drink something hot or cold, I can feel its temperature in my stomach?"
] | [
false
] | My anatomy and physiology textbook (published in 2011 so it's fairly recent) states "As a rule, pain receptors are the only receptors in viscera whose stimulation produces sensations." So why can I feel, for example, ice cold water as it travels to my stomach? | [
"The book may simply be incorrect, depending on how it classifies thermoception--or more charitably, it might not be putting things the best way it could. Thermoceptors/thermoreceptors (both spellings used) ",
" present both cutaneously ",
". Because of the involvement of you-know-what-cranial-nerve, these on... | [
"Sure, we're big-elongated-doughnut deuterstomes and all, but that didn't exactly look like the point the book was making. Receptors peppering the stomach lining would usually pretty easily qualify as \"in the viscera,\" (given the usual use of the preposition there) unless there's a point being made off-camera he... | [
"I was just trying to explain how the book's ",
" correct in a very abstruse way, but I suppose the simplest answer is that they should have said it differently.",
"unless there's a point being made off-camera here about embryonic development.",
":D"
] |
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