title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"ENT Doctors: Reason for cauterization of tongue."
] | [
false
] | [deleted] | [
"On further reflection, I am wondering if he simply was sterilizing the tool, and then used it as a tongue depressor to get a good look at your throat and tonsils, and simply did not wait long enough to let it adequately cool down."
] | [
"It's been 57 minutes without a reply, so I'm going to ask a question (as a non-expert): Why didn't you ask?"
] | [
"he didnt cauterise your tongue. The alcohol and flame are to stop the mirror fogging up. makes it easier to see. ",
"I worked an ENT post for 2 months. Only one or two of us did that. I didnt like it. Cause i was afraid Id burn somebodies tongue :)"
] |
[
"Why is it that, when I'm sick, I feel better for the first half hour or so after waking up than I'll feel all day afterwards?"
] | [
false
] | Every time I'm sick, it seems like my body tries to trick me into thinking I'm feeling better than I am first thing in the morning, then by the time I'm out the door, the symptoms hit me full force. | [
"It's the exact opposite for me. I often feel the sickest during the morning and better as the day progresses."
] | [
"This may be related with the disease that one is suffering, body response and also perception about feeling better or worse.",
"For some diseases (as common cold) there is ",
"data",
" that says that most people suffer more in the first hours after waking up."
] | [
"I experience this too, and it always pisses me off."
] |
[
"Is computer code written specifically for space travel systems written to a higher standard or in a different way then code for military, enterprise, or consumer applications?"
] | [
false
] | I’m assuming yes, but how so? Are errors mitigated by redundancies or is it a “get it right the first time” approach...or both? Thanks! | [
"Another great blunder example is the Mars Climate Probe that burned up in Mars atmosphere because some engineers worked in metric units and others in English units, and the software was never checked.",
"https://www.wired.com/2010/11/1110mars-climate-observer-report/"
] | [
"For something of a counter-example, read about the failure of the Ariane 5's first flight, caused by reusing software from Ariane 4 that had a bug that only became apparent with Ariane 5's different rocket performance.",
"https://en.wikipedia.org/wiki/Cluster_(spacecraft)#Launch_failure"
] | [
"Yes. Software for spacecraft is essential to get right. A bug could render a billion-dollar flagship program into a billion dollar piece of space junk, or on a manned flight, could cost the lives of the astronauts. NASA has, among other things, the ",
"Laboratory for Reliable Software",
" at the Jet Propulsion... |
[
"If someone gets a blood transfusion, wouldn’t they have a mishmash of genetic material appear in a DNA test?"
] | [
false
] | null | [
"From a review of an article in ",
":",
"Scientific American explains that when donor blood is mixed into the body with a transfusion, that person’s DNA will be present in your body for some days, “but its presence is unlikely to alter genetic tests significantly.” It is likely minimized because the majority of... | [
"Suppose the white blood cells from the donor, that can persist for up to a year in the blood of the recipient, have a high risk of becoming cancerous. Is there any evidence of this occurring, that is, a recipient developing cancer of a type of white blood cell that came from a donor ?",
"Theoretically yes, but t... | [
"Thank you for a very informative answer to my question. "
] |
[
"Do the conditioned reaction to a stimulus such as those in Pavlov's experiment naturally disappear over time?"
] | [
false
] | Do the conditioned reaction to a stimulus such as those in Pavlov's experiment naturally disappear over time? If so, how long would it take for conditioned reaction to disappear if both the stimulus and reward are taken away (if you no longer ring the bell or give the second stimulus that doesn't involve starving the d... | [
"Yes. This is a phenomenon called \"extinction.\"",
"After successful conditioning has been achieved, if the conditioned stimulus is no longer associated with the unconditioned stimulus, the conditioned response will fade. Using the example of Pavlov's famous experiment: If Pavlov continued ringing the bell but... | [
"Doesn't really answer the question. He's not asking about extinction from presenting the CS without the US, he's asking about extinction from presenting the US without the CS or from without presenting either the original CS or US again."
] | [
"This phenomenon you are interested in is called extinction, which just means that the link between the bell (the conditioned stimulus) and the dog salivating (the unconditioned response) fades or disappears. ",
"The usual situation is bell-food, bell-food, bell-food long enough to produce bell-salivation. Then... |
[
"What's the difference between \"Electric\" and \"Electronic\"?"
] | [
false
] | [deleted] | [
"I wrote an answer to exactly this question ",
"here",
". For convenience I reproduce it below.",
"The distinction comes from the two fields of ",
" and ",
" (which some consider a subset of the former). Electronics refers to technology that works by controlling the motion of electrons in ways that go bey... | [
"My attempt at explaining: Everything that uses / has to do with electricity is \"electric\". Batteries, light bulbs, toasters, supercomputers, certain eels, your nerves, your brain... all of that works \"thanks to electricity\", hence it is \"electric\".",
"However, using electricity to do ",
", i.e. using vol... | [
"The difference is one of scale. Electrical machines are big, electronic components are small. Although they obviously share a common base, traditionally they have been two separate areas of study. This is because the scale has a lot of implications.",
"To quote from ",
"Hughes",
":",
"Electronic systems ha... |
[
"How are nuclear arms/weapons safely created and stored to prevent accidents related to arming and detonations?"
] | [
false
] | [deleted] | [
"You can sort of chunk the history of US nuclear weapons safety into a few broad categories:",
"1940s through early 1950s: The early weapons were ",
" once assembled. They had very few safety protections. They could be set off by lightning, fires, what have you. The main safety precaution was that the nuclear c... | [
"Very simple explanation: ",
"So the core is required to be compressed in order to achieve a real nuclear blast. The core is a ball of reactive material, like plutonium. It is surrounded by shape charges that blast inward. \nOut side of that is material that add to all detonation, but not relevant here. ",
"I... | [
" was a great read. I'm a technical person but with zero background in physics or engineering, and he laid it out very well in an entertaining book to boot."
] |
[
"How much alcohol does it take to 'sterilize' a drink?"
] | [
false
] | In other words, when my sick friend wants a sip of my drink and says, "Oh, don't worry, the booze'll kill anything from me", how true is this? Also, what percentage of alcohol would be required (ie. are beer, wine, and weaker cocktails safe, too)? | [
"this article talks about killing off Montezuma's revenge (an amoeba) in drinks, but it is ",
"relevant",
"\nYou should also think about a few things: whether the alcohol is killing viruses as well, those being the main source of colds (answer: not as much...alcohol acts by \"drying out\" bacteria and any other... | [
"To actually sterilize a drink ... I think even a drink that was made of 99% ethyl alcohol would fail to be sterile, just due to the resistance of certain hardened bacterial endospores that have the potential to be anywhere.",
"I mean, these can be dormant for hundreds of years in the desert, subjected to tempera... | [
"The amount of alcohol in your drink and the length of time it would be in contact with your potential pathogens would be insufficient to \"sterilize\" a drink, or the drinking vessel. While alcohol (particularly ethanol) can be good at sterilizing surfaces, it generally needs to be 70% or more ",
" be in contac... |
[
"How effective are drugs (neuroleptic, antidepressants etc) vs psychotherapy in treating mental disorders?"
] | [
false
] | When are drugs more effective? When is psychotherapy more effective? What disorders are best treated with what? What is the effect vs placebo? Thank you for your time | [
"It really depends on the disorder. However, the most effective treatment is usually medicine combined with therapy, allowing the patient to be relieved from the symptoms via the medicine, and the therapy allowing them to gain control over the disorder. Usually the person is better off over a long period of time re... | [
"I can only speak from experience but for some disorders like schizophrenia drugs are usually the only option for any kind of relief. But i have found that for anxiety disorders behavior modification is extremely helpful. The meds just seem to mask the problem while behavior therapy helps you figure out ways to get... | [
"Antidepressants only work for severe depression, and are pretty much useless for minor depression.",
"Schizophrenia in many people cannot be managed without hard drugs.",
"It depends on the disease."
] |
[
"Some dogs and cattle have very similar coat patterns, is that controlled by the same gene?"
] | [
false
] | null | [
"Yes, many of the genes involved in pigmentation are conserved genetically across different species (especially for mammals).",
"However sometimes a \"coat pattern\" can refer to the spatial distribution of pigments and that isn't always conserved (e.g. calico patterning in female cats).",
"http://www.annualrev... | [
"So that answer would probably be yes and no. In some sense an albino cat and an albino cow are the same \"spatial distribution\" of - in this case - lack of pigment.",
"Another example is the how calico cats get their \"pattern\" from simply having a specific pigment turned off and on randomly in different cells... | [
"I recall a National Geographic article from several years ago that was examining the domestication process and specifically a long-term related experiment involving gray foxes in Siberia. It mentioned a curious correlation between domestication and spotted coats if I recall correctly. Not sure how scientific some ... |
[
"Are there any biological reasons other than UV rays why people feel so compelled to be outside in nice weather?"
] | [
false
] | null | [
"Sunlight helps regulate circadian rhythms and lack of sunlight is correlated to depression. A psychologist once told me that there is a spot on the top of your head that when exposed to sunlight helps improve mood.",
"You can speculate as to evolutionary reasons why being outside in the sun may be beneficial, b... | [
"Meteoropathy",
"Seasonal Affective Disorder",
"High prevalence of self-reported depressive mood during the winter season among Swedish senior high school students"
] | [
"Biologically, we produce Vitamin D from exposure to UV rays.",
"Fun fact, these can't penetrate windows, so now you have another reason to go outside."
] |
[
"When light is redshifted, where does the lost energy go?"
] | [
false
] | Lower frequency/higher wavelength light has less energy, so when the expansion of space redshifts light, it has less energy than it started with. What happens to this energy? It must be conserved too in some way, right? | [
"Okay so two seperate points: Lets talk about red-shifting. Think of an object at rest that emits light. Then think about that object as viewed by someone moving away from it at some speed. The observed would see a red shift in the light so where did the energy go? Well the energy is just a frame dependent quantity... | [
"When light is redshifted, where does the lost energy go?",
"It depends on the mechanism that underlies the redshifting. There are three different ones: ",
"Doppler redshift",
", which is due to relative movement between the emitter and the receiver; ",
"gravitational redshift",
", which is due to the e... | [
"I know this is very late, but I'd like to thank you for your detailed response."
] |
[
"How Do Dopamine Releases Differ Between Different Stimuli?"
] | [
false
] | I know that sexual climaxes, marijuana, amphetamines, tobacco, alcohol, exercising, and even listening to music can all release dopamine. I'm wondering if there are any differences among the reactions and, if so, what they were. Any body care to enlighten me? | [
"The rate of dopamine release is important. A leading theory of addiction supports a correlation between increasing the speed of DA release and a higher likelihood of addiction. So quicker routes of administration, eg IV or nasal are more likely to lead to an addictive habit. "
] | [
"There's no set scale. I mean, if you smoke meth you're going to get a bigger dopamine flood than if you smoke some pot... but what you're asking is largely not quantifiable due to its dependence on experiential, environmental and neurochemical variables. ",
"Now that I've said that, for me I would GUESS that if ... | [
"One thing I would consider is the difference between rate of uptake and relative bioavailability in different routes of administration. In general, BA is something like IV > Nasal = Rectal > Oral, with time to peak plasma levels following roughly the same pattern. I'd actually like to hear more about this kind of ... |
[
"If atoms are 99.9999% empty space...."
] | [
false
] | How far is each atom in relation to the other? Are the nuclei closer together? Do electron paths cross over into the adjacent atoms' space? Am I asking completely the wrong questions? I find this fact extremely mind boggling, yet very interesting! | [
"The space in the atom is fully occupied by electron(s). It is not empty in any reasonable sense. When an electron is in a bound state in an atom, it is not just that we don't know exactly where it is, it is that it literally does not have a specific position. It is like a standing wave, where the ripples are mostl... | [
"The basis for this statement is the ratio : ",
"/",
" : The non-empty parts of an atom would be those 'occupied' by electrons, protons or neutrons. However, none of these particles occupy a volume per se. There are sizes ascribed to electrons and quarks, but these are mostly a measure of how close one can get ... | [
"Pun threads are forbidden on ",
"r/askscience",
", and this rule is set ",
".",
"wink wink"
] |
[
"Astrobiology course track help"
] | [
false
] | Hey guys... Im planning on majoring in Biology and was wondering what my course track might be to eventually move my studies towards Astrobiology. I know there are only a few astrobiology programs in the country, but can I build my own course track to prepare me for a job in the field? Also, what should I do after my B... | [
"Get a B.S. but ask your adviser about teaching licensing courses, usually the difference between a B.A. and B.S. in science is a B.A. will take some courses regarding teaching/policy and a B.S. will take labs/classes on advanced research topics.",
"It is totally possible to get a B.S. and the teaching stuff too.... | [
"I'm not directly in this field but I work with several geobiologists who have done work on meteorites and such. Astrobiology is the type of field where the majority of the jobs/work will to require an advanced degree, or you'll like become involved in it as part of your advanced degree.",
"My suggestion would be... | [
"Okay, thanks. I was thinking about Stony Brook in NY for grad school, or at least part of it. Id like to eventually get a PhD. To incorporate the right classes in with my schedule would I need to eventually need to take physics classes in order to take more advanced astronomy classes, or would I need to be in an o... |
[
"When disarming a bomb, why can't you just cut all the wires?"
] | [
false
] | null | [
"I used to work as an explosives chemist. Worked with a lot of ordnance guys over the years.",
"A ",
"collapsing circuit",
" would be the main concern for someone who just randomly started cutting wires. Cut the main power source, and a solenoid (held open by electric current) closes, causing electricity to f... | [
"In the real world, bombs don't always look like a tangle of wires with some discoverable wires that you can cut to disarm it. In other words, the tv portrayal of eod is not realistic at all. The bomb typically has a casing, and in a hot situation you are not going to open that casing (it could be booby-trapped). I... | [
"think of it like this:",
"the brake lights in your car are set up to always be on; the circuit is designed that way. On the brake pedal, there is a switch that interrupts the circuit, and it's set so that when the brake pedal is up, the brake lights stay off. But, when you press the brake pedal, the switch opens... |
[
"Which is more energy efficient, internal combustion driven generator to power an electric motor, or direct drive?"
] | [
false
] | [deleted] | [
"This would only be true in a more complicated system like in some hybrid cars, where the internal combustion engine first charges a battery. This has the advantage of regulating the output of the engine, so that it can operate at maximum fuel efficiency, instead of changing in response to the required torque whil... | [
"The direct drive system could be more efficient if you always went the same speed and rarely had to accelerate from a stop. In practice this does not happen, so the engine is designed with compromises to work at variable speeds.",
"In locomotives, the diesel-electric has the advantage that the power can be dis... | [
"For locomotives, it also takes advantage of the very high amounts of low-RPM torque that electric engines, which is very important when you want to start moving a train that can weight hundreds of tons."
] |
[
"Schrodingers cat was a satirical attack on quantum uncertainty (Copenhagen Interaction), and itself isn't a valid example of the uncertainty principle. What is?"
] | [
false
] | is a fun page on it from tvtropes. | [
"Some corrections: Schrodinger's Cat has nothing to do with the uncertainty principle; it deals with the principle of superposition. Except it isn't a reductio ad absurdum of the principle of superposition itself, but rather of the Copenhagen interpretation. Note that the Copehnhagen interpretation is an intrepre... | [
"Stern-Gerlach",
" experiment is a good example. A beam of atoms is separated into two beams, distinguished by the orientation of magnetic moment. Then, one of the secondary \"pure\" beams (containing atoms all with the same magnetic moment orientation) is separated according to the magnetic moment along a diff... | [
"Thank you. As is evident, I need help understanding this "
] |
[
"Question: Looking for layman's introduction to Quantum Mechanics"
] | [
false
] | So I am looking for a good (hopefully free) resource to get a soft overview to Quantum Mechanics. More specifically I'm trying to get a handle on Electromagnetism. The wikipedia articles on Quantum Electrodynamics are a tad over my head. And just another question for any that might have an answer, I thought the force o... | [
"You'll probably want to study the classical theory of electromagnetism (Maxwell's Equations), as well as regular quantum mechanics before you tackle QED. I didn't start studying it until I was a graduate student."
] | [
"Griffiths Introduction to Quantum Mechanics is a pretty common intro text. You could probably glean a lot of meaning from it without having to do too much math or learning the notation of QM."
] | [
"Schumacher's Quantum Processes, Systems and Information is pretty easy. It starts out with some information theory and then lays out the mathematical system that quantum mechanics uses using simple examples. We're using it for an advanced QM class, and everyone loves it because it actually provides a good foundati... |
[
"How can two photons traveling parallel observe each other to be traveling at speed of light?"
] | [
false
] | My question is dealing with the fundamental ideas of Einstein's theory of relativity. Suppose we have two photons traveling side by side in the same direction. If the first photon observes the other to be traveling forward at speed c, and the other photon observes the first to be traveling forward at speed c, isn't t... | [
"If the first photon observes",
"Let me stop you there, you can't draw a reference frame for a photon to observe anything. It breaks the postulates of special relativity and this is evident in that the mathematics either blows up to infinities or non-physical zeros.",
"So the paradox you're calling out is preci... | [
"Here is a logical argument: In special relativity, light moves at the same speed in all reference frames. In an object's rest frame, the object's speed it zero. Clearly, there can't be a reference frame where light's speed is 300000km/s ",
" 0km/s. Thus, if special relativity is correct, there is no rest frame f... | [
"All evidence supports the theory, that mass-less particles travel at c in all frames of reference. ",
"Thus it stands to reason that we build our theories on this observation. "
] |
[
"Ironing. What is happening at a molecular level?"
] | [
false
] | Hello guys, I have noticed that when something is ironed when wet the wrinkles tend to be removed. When it is not wet or damped the wrinkles tend to still stay there on fabrics. Can anyone tell me what is happening on a molecular level to the molecules when wet? | [
"Irons use high heat to loosen the connections between the long polymer chains that make up the fabric of the shirt. The heated, looser fibers are now more malleable. The weight of the iron literally flattens them out, removing the wrinkles. As the fibers cool, they stiffen, and hold their now straight, unwrinkled ... | [
"Some fibers (cotton is one) need more than just the heat to properly loosen the polymer chains. The polymers most clothing is made out of falls in the hydroxyl group, which had very similar chemical properties to water. They have hydrogen and oxygen covalently bonded, and can form hydrogen bonds with the water. S... | [
"What effect does water do to the polymer chain?"
] |
[
"From what we currently know, is Teleportation of objects, alive or not, possible in the next 100 years?"
] | [
false
] | null | [
"Quantum teleportation",
" is already possible now. ",
"It's not the kind of teleportation you know from Star Trek though. It works by teleporting the quantum state of a particle onto another particle. In principle, that allows you to create an object identical to the one you want to teleport at a distance with... | [
"Teleportation isn't possible ",
" It would violate every core principle of physics we have."
] | [
"No. Absolutely not. Just like FTL."
] |
[
"You know how a tubal ligation prevents eggs from traveling down to the uterus? What happens to the eggs?"
] | [
false
] | Unfertilized eggs get sloughed out during menstruation, but if they're just getting stuck in the Fallopian tube they can't leave that way. Does the body reabsorb and if so how? | [
"During tubal ligation, menstruation would still be the shedding of the lining of the uterus but it will not include the egg because it's physically blocked from entering the uterus. The regular oestrous cycle occurs whereby the follicle develops, the hormones are released at specific points and ovulation occurs et... | [
"From what I've read, the eggs are simply reabsorbed. In male sterilisation, sperm are destroyed by macrophages as they cannot migrate from the testes so it would follow that the egg is reabsorbed too. In fact, the egg has a limited life and if it isn't fertilised by sperm then it will simply be recycled as usual."... | [
"I thought the egg is flushed out via menstruation?"
] |
[
"Did the insect (or arthropods in general) ability (or inability) to have some sort of emotion (no matter how simplistic they may be) have actually been studied?"
] | [
false
] | Title. I've seen a lot of people (and I do mean a lot) saying that insect were little more than simplistic robots due to the size of their brain, and thus that they can't have any kind of feeling or emotion (or even pain). Was it studied and confirmed in some way, or is that just a "common knowledge" (kinda like how "h... | [
"The thing is that they do not have a brain at all - at least not comparable to ours or most other animals with a spine. They have a nerve cord, which runs through their body and controls individual functions of that segment. Lacking such a central nerve system it is unlikely to have such complex functions like emo... | [
"You can't make contradictory statements like \"They do have a brain. I don't know what a brain is.\" If you don't know what it is then at best you don't know if insects have one."
] | [
"The problem is we need to define a brain. Is it just a nerve center? I'm not sure because our brain has cells or molecules that are not nerve cells, and I don't know which of these are also in insect \"brains\".",
"Regardless, they absolutely have a central nervous system, the nerve cord being part of it. The ce... |
[
"How did the apollo 11 mission protect against solar radiation?"
] | [
false
] | For that matter, how do the technologies we use today work? It seems like coating everything in lead isn't cost-effective (too much weight to launch into space) but I don't really know what they did use, but it seems they didn't have the same coatings we use today. | [
"Beyond that you shield the best you can and try to not stay out for too long.",
"This is the key. The Apollo mission went to the moon, it was a round trip of about 10 days, and the level of solar radiation they would be exposed to in that time was an acceptable risk. Going to the next closest target would be a r... | [
"In short, they dealt with the problem by making sure they weren't exposed for too long. The US Atomic Energy Commission sets acceptable does levels for workers using radioactive materials and the estimate doses for the astronauts during this time were \"significantly lower than (the limit of) 5 rem.\" ",
"1",
... | [
"This may not be the best answer but seeing as the only current response is the idiotic one by chubsthemagicwagon I'll give it brief overview. First of all we aren't great at it that is one of the major obstacles to going to mars. On earth we have atmosphere and earths magnetic field to protect us, in leo no atmosp... |
[
"Would it be possible for us to simply \"drop\" supplies onto the moon from orbit due to the lower gravity?"
] | [
false
] | [deleted] | [
"Supplies dropped in this way would still hit the surface at about 1.5 km/s which is fast but not too fast for some types of material. You could imagine packing food into a package which rolls at high speed across the lunar surface so that it could be retrieved by astronauts in a rover.",
"Its called ",
"Lithob... | [
"its harder to drop something if there is no atmosphere to allow paracute-friction.",
"landing something on a surface is tricky to get accurate. without hanging a lander from a rope with jetpacks on top of it, the landing zone is too large to try to target near or inside any large crater, your landing zone must b... | [
"You can't drop what is already falling. You have to get it out of orbit. It's currently moving at 1.7 km/s You can slow it down just a little so that the perigee is below the ground and it hits the ground, but it will hit the ground at over 1.7 km/s. You'd have to completely neutralize it. And then it would still ... |
[
"When a blend fabric is (for example) 99% nylon and 1% spandex, how does that add so much stretch to the whole garment?"
] | [
false
] | Where is the 1%? Are the individual threads 99% nylon and 1% spandex? Why does that work? | [
"The nylon is woven loosely, held by tightly woven spandex threads. Relaxed, the nylon is actually bunched up, the fabric stretches until the nylon fibers are taught.",
"Think of it like a scrunchie, where theres loose fabric around a rubber band. You can pull it open until the fabric outside is straight, then le... | [
"Thank you!"
] | [
"Great question. Additives are a huge part of material science. On a molecular level what is happening is that the molecules are wrapping around one another in a different way when just a small amount of spandex is added. It makes it harder for the nylon to wrap around itself and thus makes the material less ridged... |
[
"How many different ethnic variations of Neanderthal existed?"
] | [
false
] | Were Neanderthals all African? Were some asian? If so, did they have slanted eyes and lighter skin? Or are all these ethnic traits and difference unique to Homo Sapien? | [
"It seems there were at least three genetically distinct groups of Neanderthals:",
"source",
"While I'm unaware of any specific studies, it seems that with the time between the ",
" diaspora across Eurasia (500,000 too 200,000 years ago) and their extinction (about 30,000 years ago) would allow a fair amount ... | [
"To answer the first question, no Neanderthal remains have been found in Africa - perhaps no Neanderthals were African. The range of the Neanderthal is believed to have been limited to Europe and Central Asia.",
"Wikipedia - Neanderthal"
] | [
"If different ethnic variations did exist I'm very interested and want to know: How did we figure that out?"
] |
[
"How can I see satellites at night?"
] | [
false
] | The title. How can I with my bare eyes see satellites fly by at night? Is it the sun's reflection that I see or are the satellites equipped with their own lights? edit: Ok. I wasn't really clear. I've seen the satellites at night and what I'm asking is how it is POSSIBLE to see them with my bare eyes. | [
"You are seeing reflected light. You'all also notice that the intensity of the light goes cyclically up and down; the rate at which the albedo changes is the rate at which the satellite spins around it's axis."
] | [
"Also think about how someone in a search plane can spot the reflection from a small mirror on the ground. The mirrors specifically made for this purpose are only around 2x3 inches and can be seen for ",
"20 miles",
" in broad daylight. ",
"A satellite, though much farther away, is much larger and its reflec... | [
"It's all reflected light. They have solar panels which take up a lot of area and if the angle is right, it's like someone is using a mirror to bounce sunlight at you. If you want to know when are where to look for satellites (the Iridium flares are always a great see) you can use",
"http://www.heavens-above.co... |
[
"Is it possible to kill a house fly with a static charge that you have accumulated?"
] | [
false
] | null | [
"This only talks about the voltage, not the current. "
] | [
"This is correct. Current is what causes damage in biological tissue."
] | [
"As my physics teacher used to say, volts jolt, and mills (milliamps) kill."
] |
[
"How is energy produced by nuclear fusion captured? And what form is this energy in?"
] | [
false
] | I know that energy from coal or nuclear powered plants etc is transferred through steam powered turbines, but how exactly would the energy given off by fusion be captured? | [
"I actually just threw an answer up in ",
"this thread",
". Assuming they ever create a self-sustaining, net-energy-producing fusion reaction, they are probably just going to boil water with it until somebody comes up with a better idea."
] | [
"The most commonly suggested concept is that power will be captured like it is in other power plants, through boiling water. ",
"Alternatively, there is a method called direct conversion where the charged particles produced by fusion are passed through a small tube, and generate a current as they go through, whi... | [
"Most of the energy from deuterium-tritium fusion comes out in the form of 14 MeV neutrons. One way to capitalize on these neutrons is to surround the fusion reactor with a blanket of fissionable material and convert the 14 MeV neutrons via fission, multiplying their energy by a factor of around 14 to 15 and extrac... |
[
"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! ... | [
"[Neuroscience] \nIt’s said that, when you go though some trauma (I’m thinking about ptsd) your brain is physically damaged in the process. How can that happen? How does that actually happen? (So what is damaged and how)",
"Thanks!"
] | [
"The electricity in our bodies certainly dissipates when we die. Your body is constantly using food as fuel to pump salt ions across a cell membrane—this charge separation is the principal underlying batteries. Once we die, our bodies no longer fight entropy, so the separated charges will mix, eliminating the “elec... | [
"If a physically and psychologically healthy person experiences no significant situations of fear, stress or excitement on any given day, will adrenaline still have a role to play in their bodily function on that day?",
"In other words, does adrenaline have a role to play outside of the fight-or-flight response?"... |
[
"How can neutron stars have a magnetic field if neutrons are neutral?"
] | [
false
] | Both normal neutron stars and magnetars | [
"How can atoms have a magnetic field if atoms are neutral?",
"Neutrons do actually have a magnetic field. However, the magnetic fields of neutron stars mostly comes from magnetic dynamos. Neutron stars are composed of more than just neutrons, there are also electrons, protons, and even whole atoms (in a thin surf... | [
"It's believed to be solid, and tectonically active producing \"starquakes\".",
"http://www.nasa.gov/content/goddard/nasas-fermi-satellite-finds-hints-of-starquakes-in-magnetar-storm"
] | [
"To further explain. The neutron has no ",
", but the quarks they are made of do.",
"https://en.wikipedia.org/wiki/Neutron_magnetic_moment",
"For an elementary particle to have an intrinsic magnetic moment, it must have both spin and electric charge. The neutron has spin 1/2 ħ, but it has no net charge. The e... |
[
"How do plants know which direction to lean towards in search of light?"
] | [
false
] | For instance, indoors where there's minimal light coming from one window like 30 ft away. Does the plant sense the UV radiation similar to how we feel 'hot' vs 'cold'? | [
"In a nutshell, yes. At the tips of the plant shoots are hormones called auxins, which are responsive to light and function in making the plant get taller. They auxins themselves are negatively phototropic, which means they migrate to the side of the plant that is getting less sunlight. So, shine a light from th... | [
"Auxins also work to enable gravitropism, which is plants growing towards (positive gravitropism) or away from (negative gravitropism) the force of gravity.",
"Auxins are positively gravitropic, which means they go \"down\". Roots respond to auxin the opposite way ",
" shoot cells do, growing slower with auxin.... | [
"Roots respond to auxin the opposite way shit cells do",
"Uhhh, k?"
] |
[
"OK, fess up cosmologists; to what extent is \"dark energy\" just a fudge factor to make general relativity work on a cosmological scale?"
] | [
false
] | My understanding is that dark energy is needed to explain the accelerating expansion of the universe. Since we know that general relativity doesn't handle subatomic/quantum scales very well, isn't it reasonable to conjecture that it is breaking down at the cosmological scales as well, rather than imagine a mysterious e... | [
"Sort of...Einstein initially put it into his equations and gave it a specific value to make the universe static and stable-which it appeared to be at the time. Later, Hubble observed that the universe was in fact not static but expanding, suggesting a value of zero. Around this time, Friedmann, Lemaitre, Robertson... | [
"\"Dark energy\" is an umbrella term for all mechanisms that could explain the accelerated expansion of the Universe. The cosmological constant (CC) is only the simplest explanation, but most people don't really expect it to be the answer. It also corresponds to vacuum energy, which we expect to be there from quant... | [
"I don't think that idea is being taken seriously by anybody. At least I have never heard of it in any of the many talks or papers about alternative theories I have attended or read."
] |
[
"When discussing anthropomorphic causes of climate change, why does it seem only atmospheric emissions are considered?"
] | [
false
] | Some of the things I wonder about contributing are the heat sinks created by dams and cities, the changes in wind patterns from cutting the tops off mountains and building mountain ranges called cities in other places, pumping oil ect. out of the ground by pumping in water and so forth. My current thought is about the ... | [
"Interesting question, it is well known that human structures have an impact on local climate. ",
"Heat Island effect",
" is well known in cities that are often several degrees warmer at night than the surrounding countryside.",
"Bur on a grand scale of things, human structures are quite tiny compared to moun... | [
"So are you saying that cooling from the core or the effects or mountains rising from pumping water from underneath them or cities sinking because they are heavy would have no effect on the climate compared to the sun light? It just seems to me that tidal forces and increases in tectonic activity might contribute t... | [
"Well, big volcanic eruptions undeniably affect climate. But you already know. "
] |
[
"Could a woman deform her breasts if she sleeps on her stomach every night?"
] | [
false
] | Sorry to be a boob, but I have been looking online for the answer to this for a while and all the info I find is related to breast augmentation. If a woman with small/regular sized implant-free boobs slept on her stomach every night, would she be more likely to sag or have deformities in her breasts later on in life, o... | [
"Breast sagging, or ptosis, has not been significantly linked with sleeping on your stomach. A ",
"2010 study",
" concluded that \"age, history of significant (>50 lbs) weight loss, higher body mass index, larger bra cup size, number of pregnancies, and smoking history were found to be significant risk factors... | [
"Just a reminder of the ",
"guidelines",
" of this subreddit. ",
"Please keep posts on topic, and refrain from speculation (\"My guess is this...\"), anecdotes (\"My wife sleeps on her stomach and her breasts are...\"), and jokes (\"I think we need pictures for this!\"). ",
"Use that handy report button w... | [
"I'm wondering about that old wives tale of placing ice on breasts every night to prevent ptosis. I'm too lazy to search myself (running/quantifying some big expts right now), do you have any info on that?",
":",
"This case is completely different from sleeping on your chest, it has nothing to do with it. There... |
[
"Weather balloons that are sent up with cameras eventually pop when the air pressure gets too low. What if a second balloon was attached that had, say, 1/4 of the normal helium? Would it rise up significantly higher?"
] | [
false
] | null | [
"Let’s look at our system, we have two balloons providing a buoyancy force which is greater than the gravitational force. When we pop one balloon the system still has a buoyancy force larger than the gravitational force. This is what our system looks like in equation form:",
"Fi > Fg where Fi = Fl + Fs",
"Ff > ... | [
"You don't need an indestructible balloon to reach a neutral buoyancy and it is done fairly often for long term balloon campaigns.",
"Same with the 1/4 filled balloon, it won't rise forever and if we assume it does not pop or lose and helium it will just reach an equilibrium height and keep on floating along.",
... | [
"The higher up in the atmosphere you go, the lower the air pressure.",
" As a weather balloon gets higher, the gas inside the balloon expands, increasing the size of the balloon. The balloon eventually grows to a ",
"certain size",
" and bursts. The payload has a parachute, and is able to be recovered."
] |
[
"When it is said that someone \"died peacefully in their sleep\" was it actually peaceful?"
] | [
false
] | What are the main causes of death for dying in your sleep? Have any studies been done to determine if dying this way is actually painless? | [
"Citations for all of this, please. I have no idea who 'astruc' is."
] | [
"First of all, you mis-cited the user who posted it (it's ",
"biscotti",
"). Second, "
] | [
"It means peaceful for others. Nobody heard agony of death. "
] |
[
"Is contagious yawning a cultural/learned thing or is it hardwired into us?"
] | [
false
] | When I see someone else yawn it's almost automatic that I will yawn. Even just writing this made me yawn. But I've noticed that my young children don't do this. So is my instinct to yawn because there is some innate connection in human brains or is this something I do because grew up around would do it and I learned it... | [
"Contagious yawning happens in animals and between species as well. Doesn't really answer the question of whether it's cultural or biological though, sorry.",
"https://www.npr.org/sections/health-shots/2017/05/15/527106576/yawning-may-promote-social-bonding-even-between-dogs-and-humans"
] | [
"You will find ",
"this article",
" very fascinating. Here is an excerpt. ",
"When it rains, some orangutans make umbrellas out of branches and leaves to cover their heads. It’s quite unlikely that this behavior is genetic. Orangutans likely aren’t born with the knowledge and capability to build umbrellas in ... | [
"We have something called mirror neurons, which some psychologists believe are involved in developing empathy. When you see someone sad, your mirror neurons will register the facial expression as sad, and then depending on your upbringing/nurture you will act based on that (maybe you ignore the sad person, maybe s... |
[
"How do speakers produce multiple frequencies at once?"
] | [
false
] | null | [
"The waves add up to make one complex wave. For example, look at this picture of three waves being added together. Your speaker would just play the complex wave on the right when you tell it to play the three waves on the left.",
"http://x2.i-dat.org/~csem/UNESCO/4/imgs/FIG3-01.gif"
] | [
"More detailed version:\nAn audio signal is just one big ugly wave. When people talk about a single frequency in audio they mean a sine wave at that frequency. You can prove mathematically that any waveform is equivalent to the sum of an infinite series of sine waves, called a Fourier series. If you have a complex ... | [
"That's a very interesting question and one I've had myself before. As someone that was obsessed with speakers and audio (and still is), I've had it explained on loudspeaker mailing lists as this- no matter how complex the waveform, the whole thing can be condensed down to the fact that the speaker's cone only has... |
[
"What is the strongest magnifying lens without a handle?"
] | [
false
] | null | [
"Do you mean that you can buy? We don't offer product advice on this sub"
] | [
"Ok, sorry I was unsure where to post this, where should I post it?"
] | [
"Not sure. You can post to ",
"/r/findasubreddit",
" -- they can help find an appropriate sub"
] |
[
"If time slows the closer to the speed of light someone travels, what is the effect on an airline pilot over the course of their career?"
] | [
false
] | Of course, we'll have to do some assumptions her, and I'll start. Any more assumptions and I'll edit them in with an asterisk. *And please show the reasoning behind it, so that I can further understand the concepts. | [
"Since you asked for a step-by-step approach with actual numbers, I'll try to break this down a bit.",
"The easiest thought experiment here is to imagine a laser-clock that is defined by two mirrors ",
"A",
" and ",
"B",
", separated by a distance L:",
"mirror A mirror B\n | |\n |--------»... | [
"On the order of microseconds."
] | [
"Your feet age at a slightly different rate than your head. "
] |
[
"Doesn't Jevons paradox imply that any attempt to \"solve\" the oil crisis with more fuel efficient cars will only make it worse?"
] | [
false
] | For the unfamiliar, means that an improvement in the efficiency of the use of a resource, rather than decrease consumption, actually means that it will increase consumption of that resource. Apply to the oil and transportation industry this means something rather disturbing: If we simply increase the efficiency of all ... | [
"I think this may not happen. First off, the reason increased efficiency can increase consumption is because it lowers the price of using one unit of resource, thereby making it a better deal to use that resource to do things. So if the price of driving 1 mile decreases, then there are more situations where it's ... | [
"I would really like to see the source for these numbers. 828 cars per capita??? Are you using a definition of per capita that is not \"per person\"?"
] | [
"Following the references from the Wikipedia article you cited leads to ",
"this report",
" on \"The Effect of Improved Fuel Economy on Vehicle Miles Traveled: Estimating the Rebound Effect Using U.S. State Data, 1966-2001\". A shorter version appears to have been published in Energy Journal, vol. 28, no. 1 (20... |
[
"Why does everybody say nothing can go faster than light?"
] | [
false
] | null | [
"\"Gravitation is stronger than the speed of light\" doesn't make any sense. Even when black holes are involved, nothing can move locally faster than c."
] | [
"No matter how strong the black hole is, an observer near the photon will always see it moving at c."
] | [
"No matter how strong the black hole is, an observer near the photon will always see it moving at c."
] |
[
"How big is the size of the shadow when the ISS transits the sun?"
] | [
false
] | null | [
"That just depends on how far away the ISS is from the observer, and how big the ISS is. The small-angle formula (and this is a small angle!) gives",
"theta = ISS_size / distance , in radians.",
"Looking up the size of the ISS, I see it's about 75 m x 100m or so; let's use ISS_size =100m number because it wil... | [
"The penumbral shadow is basically as big as the ISS when both it and the Sun are directly overhead. That's because the Sun is so far away. At the maximum inclination of the ISS orbit of 51 degrees and the Earth's axial tilt is at the maximum of 23.4 degrees, the shadow gets much longer. The time of day also has a ... | [
"So basically, there is no full shadow. Only a lot of half shadow.",
"Just as if you put a needle in front of a lightbulb."
] |
[
"Can someone please tell me what type of fungus [this is](http://imgur.com/oGRSp)?"
] | [
false
] | Found near a playground. edit: link to image is , and is also provided below by the helpful astanix. | [
"http://www.reddit.com/r/mycology"
] | [
"http://imgur.com/oGRSp",
"For the lazy."
] | [
" aka Chicken of the Woods",
"One of the most delicious wild edibles."
] |
[
"What is the practical progress of Quantum Computing? Will we see home versions any time soon?"
] | [
false
] | null | [
"The number 143 was factored",
" and ",
"D-Wave claims to have created a computer utilizing 84 qubits.",
"In short, we have relatively little practical progress. These computers are very small and only perform simple tasks. Moreover, they're incredibly expensive.",
"Consumer versions are not likely in the n... | [
"Let's not forget the algorithms for these machines have to be completely different. Theoreticians have worked up a couple of different one's but there are probably a great many more algorithms which can be run on a quantum computer.",
"http://en.wikipedia.org/wiki/Quantum_algorithm",
"However, if we examine th... | [
"Quantum computing is coming along, but it will be a while before it is actually a viable technology. The current top end technologies are D-wave's 'quantum computer' (in quotes because how quantum it is has been under dispute - it certainly doesn't allow all algorithms, such as Shor's Algorithm), which claims to h... |
[
"Is it possible for a living being to exist outside of our Visible Spectrum of light?"
] | [
false
] | For example a creature that only reflects UV light. I started thinking this because I had read that Bees can see UV. | [
"In order for it to be invisible to us it would have to reflect UV light and flawlessly ",
" visible light. Otherwise we'd see blackness/distortion where it was standing."
] | [
"You see stuff because light is reflected off them. Living \"outside of our visible sprectrum\" doesn't really makes sense. Two ways to approach that :",
"1 - It absorbs visible light : we call that being black.",
"2 - Visible light can pass through it : we call that being transparent. ",
"And yes, some organ... | [
"well distortion can mean things like glass. and it would only be black if it perfectly absorbed visible light. if not it would be like a regular object. so maybe not so creepy."
] |
[
"When I touch a wall, what color is the light?"
] | [
false
] | Ok, so that's a pretty silly way to phrase my question, but my thinking is this: When I touch a wall with my finger, the electrons on the outside of the outer molecules of my finger repel from the electrons on the outside of the outer molecules of the wall. In order for this to happen, photons must be transmitted betwe... | [
"First, note that the photons that supposedly appear between your finger and the wall are what we call virtual photons. Now I will paste ",
"my response to a similar question",
" since it comes up so often:",
"Virtual particles definitely do not exist.",
"When doing quantum field theory (QFT), you can work ... | [
"The interaction between electric fields are mediated by \"",
"virtual photons",
",\" which exists only as long as the interaction requires, and is different from the real photons we observe."
] | [
"I'm not sure if this is relevant, but Wikipedia says ",
"(existing importantly only within a few wavelengths of the field-disturbance which carries information or transferred power)",
"That suggests to me that virtual photons have a wavelength too, although since I'm not 100% sure what it's talking about, mayb... |
[
"How many years ago did Asians have a Common Ancestor with Europeans?"
] | [
false
] | [deleted] | [
"Interesting that you asked this question now, as a ",
"rather substantial paper was published in Science",
" just this week on the very issue of human dispersals out of Africa. I haven't had a chance to read it yet, but I know that it identifies Aboriginal Australians as the first population to leave Africa, a... | [
"Not an expert, but that doesn't really answer his question, right? There's been so much exchange between Europe and Asia throughout history that the MRCA should be earlier than the \"out of Africa\" epoch. The exchange has been pervasive and crosses many time periods - think of the \"wandering peoples\" coming fro... | [
"Perhaps you need to be a little more specific with your question.",
"Since you phrase it as \"how far back to find a common ancestor between a Chinese and a French person\", the implication is that you mean ",
" common ancestor, no matter how small their contribution to your ancestry is.",
"In that case, our... |
[
"Is the Hydronium ion just as likely to occur as Ammonium Ion during a basic water and ammonia reaction?"
] | [
false
] | This is probably a simple question but I'm struggling with understanding basic trends in chemical reactions. The equation in question: "NH3 + H2O = NH4+ + OH-" Why is the ammonium ion and hydroxide the product of this (reversible) reaction? Why does the hydrogen pair with the nitrogen over the oxygen? Is H3O+ also crea... | [
"The Kb for ammonia is larger than the Kb for water, so ammonium is far more likely a product than hydronium. To produce hydronium from a reaction between ammonia and water, the transferred hydrogen ion needs to come from the ammonia, which would produce the NH2- anion. The Kb for this anion would be even larger th... | [
"Thanks for taking the time, very well written and easy to understand. "
] | [
"Let's look at a similar series of reactions, the acid dissociation reactions of NH3, H2O, and HF. The F is the most electronegative, so that hydrogen is the most acidic. The hydrogen on oxygen is the next most acidic, and the hydrogen on nitrogen is least. This is why HF is an acid, water is neutral, and ammonia i... |
[
"When I froze a cup of water, why did this happen?"
] | [
false
] | Just a cup of water, probably lukewarm water. We sat it on a level pizza box in the freezer, and it came out like this. Anyone know why or how? | [
"there's a name for this and i can't remember it at the moment- but basically it comes about because the surface freezes first, then as the rest continues to freeze, that increases the pressure (because of course ice is less dense than liquid water) and at some weak point breaks the frozen surface and squeezes some... | [
"The name you're looking for is simply ",
"ice spike",
"."
] | [
"This was answered in ",
"/r/sciencefaq",
" ",
"here",
". Please follow the instructions on the sidepanel when posting.",
"Before you submit, please try to improve your post by using Google, ",
"/r/sciencefaqs",
", and searching this subreddit for similar questions. It makes it easier for panelists an... |
[
"Question about mRNA vaccines: what stops production of the new proteins?"
] | [
false
] | So I get that the mRNA bonds with host cells, the host cells then begin producing the protein encoded by the mRNA, and the immune system learns to fight that protein. What stops the process? Will the host cells make the new protein forever? Can the mRNA replicate inside a host cell? | [
"mRNA degrades very quickly naturally. Cells contain endogenous RNAses as well, this is specifically one of the advantages of mRNA vaccines, RNA is short lived and will provide a burst of protein translation before it's degraded by the cell and the nucleotides are recycled. ",
"That burst of protein then gets pro... | [
"mRNA stands for \"messenger RNA\", and it's like an order pad instruction for the kitchen to make a thing. We're sneaking our instruction into the kitchen: it's something they can make, but usually don't make.",
"The kitchen has recycle bins and shredders to tidy up old messages, because old messages aren't usef... | [
"For the last question, no the mRNA shouldn’t be able to be replicated in human cells, so once it’s degraded naturally it will be gone.",
"In order to replicate mRNA you need an enzyme called reverse transcriptase to transcribe it back into DNA which then human cells can replicate. This is how RNA based viruses m... |
[
"Can you die from Pfizer second dose?"
] | [
false
] | null | [
"You need to talk to a doctor and not Reddit."
] | [
"They don't bother, all they say it's the vaccine"
] | [
"You need to talk to a doctor, not Reddit."
] |
[
"Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science"
] | [
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! ... | [
"Is it truly feasible for human life to ever inhabit another planet? It seems as any adult would be long dead by the time we reached a habitable planet."
] | [
"how are we supposed to use our laws of physics to explain something that breaks our laws of physics?"
] | [
"how are we supposed to use our laws of physics to explain something that breaks our laws of physics?"
] |
[
"How are newly manufactured \"empty\" computers programmed before you can install higher level programming software on them?"
] | [
false
] | I was programming and then I thought that the programming software is also programmed by somebody. But if every program is programmed with a programming software then who and how programmed the first programming software? My boyfriend says that robots place the boot code in the BIOS when new computers are manufactured.... | [
"It's a process called \"bootstrapping\", which is why it's called \"booting\" a computer, it refers to \"lifting one's self up with one's bootstraps\".",
"In very very old computers, you would first manually enter a series of instructions on switches: you would have 8 switches and an \"execute\" button, and manu... | [
"Computer Science grad student here. With regards to contemporary \"programming software\", you do not really have to go back into a history lesson for everything. Today majority of the \"first software\" is written in C, a mid-level programming language. The compiler for C is also usually written in C ... an old c... | [
"CPU chips have programming in them called micro code. It figures out how to handle the assembly level instructions and what to do with them. ",
"The computer first has to run a program when it is turned on. Typically it will be in the ROM of the computer, and is fired from an interrupt that signals that the CPU ... |
[
"Is terminal velocity a constant regardless of aerodynamicy?"
] | [
false
] | null | [
"The terminal velocity of an object depends on its drag coefficient."
] | [
"Do you mind elaborating? "
] | [
"The answer to your question is no.",
"If the drag force is ",
" = -cv",
", then the terminal velocity is",
"v",
" = sqrt(mg/c).",
"c is a constant which quantifies the \"aerodynamicity\" of the object. So the terminal velocity depends on how aerodynamic it is."
] |
[
"Do we know how long dinosaurs lived?"
] | [
false
] | I'm talking about each individual dinosaur, not the time period. Did T-Rex live for 10, 50, or 100 years? Do we have this information? | [
"Yes, we do. For some.",
"Or at least we have an idea.",
"Animals tend to grow seasonally, with more growth in warmer weather and less in colder weather. This results in what are called \"lines of arrested growth\" or \"LAGs\" for short. As an analogy, you can think of them sort of like tree rings for animals."... | [
"For those interested: this methodology is called ",
"Sclerochronology",
". "
] | [
"Thats an interesting methodology. But you're not actually examining a bone, you're examining a fossil, which is sediment that filled the void where a decayed bone laid then hardened. So how are you seeing anything about the internal structure and detail of these LAGs?",
"Do you have actual dinosaur bones?"
] |
[
"Physics photoelectric effect question. Why are larger atoms more likely to undergo photoelectric absorption?"
] | [
false
] | My textbook says this: "The clinical significance of photoelectric absorption depends on the fact that the frequency of photoelectric interaction varies directly with the third power of the atomic number of the absorber. For example, because the effective atomic number of compact bone (Z = 13.8) is greater than that of... | [
"\"I figured larger atoms have more protons and thus have a stronger attractive force the their electrons.\"",
"Actually it's not true - larger atoms have a lower attractive pull on the electrons. The lower electrons 'screen' the positive nuclear charge from the outside electrons, which reduces the pull from the ... | [
"Haha, yeah any question about photons here in AskScience gets one answer from the semiconductor people, a different one from the medical imaging people, and sometimes a third answer from the high-energy people. I only have a very basic understanding of anything that happens under 1 keV."
] | [
"This is actually not true - the greater increase in probabilities does not make promoting an electron more 'likely' to happen. In fact, the photoelectric effect is not about how likely it is to happen, but rather, the minimum energy required to make it happen."
] |
[
"How different is getting burned by 100 °C and 1000 °C or higher?"
] | [
false
] | null | [
"It depends on the length of time you're getting exposed, a nanosecond at 1000C won't do anything,but a second would probably cause 3rd degree burns. You can quickly dip your hang in boiling water, and get away with a light scalding, but if you hold your hand in it you'll be lucky to get away with 2nd degree burns.... | [
"3rd degree burns cause permanent nerve damage, and there would likely be quite a bit of charred flesh. 1000C would permanently disfigure you, so I'm not sure what you're going for here"
] | [
"Lets suppose that it´s a few second. "
] |
[
"Is there a lower bound to how much energy a photon can lose due to red-shifting?"
] | [
false
] | My understanding is that a photon which escapes a gravity well will be red-shifted due to the energy lost (increased wavelength). Given the gravity well of an *arbitrarily massive* body, is there no limit to the amount of energy lost from a photon escaping at an angle perfectly opposite to that of the gravitational pul... | [
"It can lose an arbitrarily small amount of energy."
] | [
"Is there a lower bound to how much energy a photon can lose due to red-shifting?",
"No, the lower the mass of the body, the less energy is lost, all the way down to zero. I guess if one wants to be nitpicky then the mass of the body cant be arbitrarily small due to having to be built up from massive particles, a... | [
"No."
] |
[
"Can somebody explain the results from this “accidental” experiment I did?"
] | [
false
] | null | [
"Perhaps ",
"/r/askchemistry",
", ",
"/r/askreddit",
", ",
"/r/asksciencediscussion",
" or a similar sub. You can use ",
"/r/findareddit",
" or ",
"/r/findasubreddit",
" (I don't remember which) to help you find subs in general"
] | [
"We can't really comment on anecdotes / isolated incidents without resorting to speculation which we try to avoid."
] | [
"Ok I apologise, is there a better place to post this or anywhere you could appoint me to where I can find an explanation?",
"Thanks"
] |
[
"I was taught in science class a few weeks ago that the row in the periodic table is representative of how many shells the atoms contained within have. However, I was also taught that the order of electrons per shell was 2, 8, 18, whereas the periodic table has 2, 8, 8, 18. Which is incorrect?"
] | [
false
] | null | [
"Both are correct. As the atomic number goes up, electrons start filling up the fourth shell ",
" completing the third shell. So an element like potassium has only 8 electrons in its third shell, but it has one electron in its fourth shell, thereby belonging to the fourth period.",
"This happens because each sh... | [
"They are sort of both right. The first three shells do indeed hold, 2, 8, and 18 electrons respectively, but it to understand the layout of the periodic table you need to understand the make up of these shells. The first shell consists of a single s-orbital that can have two electrons in it. The second shell has a... | [
"This image",
" should help OP visualize it."
] |
[
"Could being dehydrated/hungry when you go to sleep impair body growth or maintenance?"
] | [
false
] | null | [
"Hi SansFinalGuardian thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of t... | [
"'Human Body'"
] | [
"Human Body"
] |
[
"What distance has to be covered on a bike to charge a smartphone?"
] | [
false
] | What implications/limitations/issues would this have? | [
"Well, Zero distance if you had a stationary. Most stationary bikes at the gym are self powered by your pedaling. For years you could buy headlights that are self powered. you could convert that generator to a cell charger. TO find out the distance..",
"Read ",
"http://inhabitat.com/bike-powered-cellphone-charg... | [
"No, just curiosity"
] | [
"No, just curiosity"
] |
[
"If it's true that under a certain depth of water blood appears green, why is that?"
] | [
false
] | null | [
"Actually, yes, as bizarre as this may sound at first, it is certainly true that blood appears green at a certain depth underwater when illuminated by sunlight as you can clearly see ",
"in this video",
". ",
"The reason for this effect is not that the blood itself is changing color, but rather because the su... | [
"Is that why many fish are red? They'd evolve those colours to appear dark or colourless to their predators at depth but would appear red on the surface..?"
] | [
"Oceanographer here. Lots of critters that live in the mesopelagic part of the ocean (more than ~400 meters deep) are red for this reason. This doesn't apply to fish that live in the surface ocean, because there's still sufficient light for them to be seen even if they appear green. Animals in the \"twilight zone\"... |
[
"Lexus claims to have produced a 'future-proof' hybrid engine, capable of 'optimizing any fuel source on the planet'. How is this possible? [link inside]"
] | [
false
] | frustratingly vague recent Lexus | [
"This is mostly a gimmick. A well designed Diesel engine can run on almost any combustible fuel. Diesel fuel (as it has come to be called) is used primarily for it's high energy density, and low volatility. ",
"I will say, it seems like they are hinting at adjustable timing systems, as wherein mentioned. I'm not ... | [
"Adjustable ignition timing and ability to adjust compression ratios to be able to oil ignition."
] | [
"AKA a tune-able diesel engine with spark ignition."
] |
[
"If for smooth video you need 24 fps, what is the hearing equivalent?"
] | [
false
] | [deleted] | [
"Your question appears at first to be comparing apples with giraffes as you are looking at two very different processes.",
"Seeing smooth video means that you are not seeing the discrete frames, ",
"but are fusing them together",
".This is essentially an artifact of the limitations in our visual system that m... | [
"Alternatively viewing both as a sampling problem does lead to a somewhat decent comparison. As you pointed out that if the frequency of the flashing light is too high our brain fuses images. Technically we can view this as distortion of the signal (on the alternating pixel value, not the image you want to see on s... | [
"A side comment concerning your question. The 24 fps you refer to as \"needed\" for a smooth video isn't quite true. It may be necessary to perceive smooth MOTION in the video, but if nothing in the video is \"moving\" from frame to frame, a 1 fps video would be indistinguishable from a 24 fps video, as long as t... |
[
"Are the same areas of the brain used when recalling music as those used when listening to music?"
] | [
false
] | If I recall a song, let's say , I can hear all of the instruments and vocals in my head. What is happening neurologically when I do this? Is it at all similar to what occurs when actually hearing the song? In a simple case, for instance a 440 Hz tone, are the same neurons that fire when hearing the tone being stimula... | [
"The one word answer is ",
"yes",
".",
"But, when you're hearing a sound, there's ",
" a bunch of basic auditory collection and processing centers (cochlea/thalamus/inferior colliculus/etc.) activated. It's just the same neurons in the primary auditory cortex that get activated both when imagining and when... | [
"I don't know about audio, but when asked to visually imagine things the brain does recruit some of the same areas used in visual perception. I'm trying to find a citation but having trouble at the moment. I think that the low level visual areas (retina, V1-V4) are not involved in visual imagination, but some of th... | [
"That's interesting, thanks. I don't have access to ",
", though, so perhaps you can shed some light on my next question:",
"What is activating the neurons in the primary auditory cortex if it's not the basic auditory collection and processing centers? I would guess that another part of the brain associated w... |
[
"why do black holes increase in size if the singularity has infinite density?"
] | [
false
] | In alot of online articles they state that the singularity has infinite density. So when a black hole consumes an object (goes past the event horizon) why does the size of the black hole increase? Wouldn't the mass just be squeezed infinitely without altering the size of the black hole? | [
"I think you're getting mixed up by the two \"length scales\" that one might consider here. One is that of the singularity, which in a classical theory is infinitely small, infinitely dense, and those two facts stay the same as the mass of the black hole grows. (We don't yet have an good quantum theory of gravity... | [
"So. The singularity doesn't increase in size itself. But due the added mass, the event horizon radius does. Correct?"
] | [
"Right.",
"We don't know if there is really a singularity, but that doesn't matter for what we observe outside."
] |
[
"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! ... | [
"When you are conducting a survey, and you ask something like, \"Do you prefer A or B?\" - is there the possibility that it could be affected by people preferring 'Option A' or Option B'?",
"For example, they will always prefer the option presented first or last, or will always prefer the option assigned to a cer... | [
"Yes, this happens a lot and researchers try to screen for this, but also have math/statistics formulas to account for this, which is a type of bias in the raw data. Honestly, it can't be entirely eliminated because you can never know which subjects are being 100% honest/truthful, which is why researchers use these... | [
"When working out there is a range of recommended protein intake (depending on who you ask, between 0.8 and 1.4 grams per pound of lean body mass, per day).",
"But... the protein in the meals is also included in the caloric values of the foods you eat, and ends up being a very large component of the daily recomme... |
[
"A curious question about evolution"
] | [
false
] | [deleted] | [
"neither came from either. Vertebrates are thought to have evolved from soft-bodied invertebrates like ",
"tunicates",
" (tunicates are, in fact part of the phylum chordata). Arthropods are thought to have evolved from segmented invertebrate animals with hardened exteriors. Ie, the common ancestor of vertebrate... | [
"The question of exoskeletons vs. endoskeletons goes a long way back about 600 million years back approximately.",
"What you need to understand is that these two body forms didn't even really exist at the time when the divergence happened. The first step down the road to \"arthropods\" and \"chordates\" wasn't so... | [
"is there some evolutionary \"trigger\" that chose how they would evolve in that way? ",
"The short answer is: no.",
"The slightly longer answer is: given enough individuals and generations (i.e. time), all changes and mutations that can happen will happen. Harmful mutations will die out, neutral and beneficia... |
[
"I just spent a Canadian quarter at the local American McDonald's and received a Canadian penny in my change. Numismatists of Reddit, Is there any significant economic impact of foreign currency exchanged like this?"
] | [
false
] | Insight from Reddit's students of currency will be looked upon with great awe. | [
"Considering the very nearly equal value and expecting that roughly equal amounts of currency will be introduced in both directions along with the very small actual value of pocket change...",
"the economic effect should be quite low."
] | [
"colechristensen's comment is right but let's look to the most extreme situation to see if it might matter.",
"At the worst in the last 20 years, the Canadian dollar was 60 American cents. Let's pretend there's a daily imbalance of 100,000 more Canadian quarters being spent in America than American quarters spent... | [
"American money is ALWAYS mixed in with our money here in Canada. Is it that way in the States or is it a more rare thing?"
] |
[
"What sort of reaction would occur if you were to mix anti-hydrogen with anti-oxygen?"
] | [
false
] | Rather than make anti-water would you make fire or something? I heard my Chemistry teacher (I'm doing level 2 currently) talk about anti-hydrogen but didn't explain further about any of it mechanics and what not, so I figured if there's anti-hydrogen why not anti-oxygen? and what would happen if you mixed the two. | [
"Just like mixing oxygen and hydrogen, you would get no reaction.",
"Until you add a spark.",
"Then you get both fire and water.",
"In an antimatter system, you would get the same: fire and 'anti water' - that is, a substance that behaves like water, but it made of anti protons anti electrons etc.",
"Here's... | [
"From my understanding you could just use heat, so radiation, to heat the anti mixture to it's combustion point."
] | [
"From my understanding you could just use heat, so radiation, to heat the anti mixture to it's combustion point."
] |
[
"LTP and LTD in the mesolimbic system contributing to addiction"
] | [
false
] | [deleted] | [
"LTP is the way that connections between neurons, synapses, are strengthened. LTD is the process by which synapses are weakened. LTD is thought to result mainly from a decrease in postsynaptic receptor density or a decrease in presynaptic neurotransmitter release. When you use drugs, it is believed that you feel dr... | [
"Do you think it will be possible in the foreseeable future to block down regulation? It would be cool if you could take drugs without getting addicted or having a diminishing effect. "
] | [
"From \"Nucleus Accumbens Long-Term Depression and the Expression of Behavioral Sensitization\" Brebner et al 2005 Science:",
"\"Within a given nucleus such as the NAc, it is suggested that the relative balance between LTP and LTD at different afferent inputs determines the expression of specific patterns of beha... |
[
"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! ... | [
"If I go into the rain forest wearing bright colors like red or yellow, colors traditionally used by poisonous animals, will predators tend to avoid me?"
] | [
"More like patterns of responsiveness, via long-term potentiation of some synapses. So certain neurons tend to fire together, in principle representing the elements of a memory (and probably a connection to things that trigger recollection - could be a neuron that fires in reaction to a particular smell)."
] | [
"Assuming Hardy-Weinberg equilibrium, never. The genotype frequencies remain the same from generation to generation*, including the frequency of homozygotes for the recessive allele.",
"*p",
" / 2pq / q",
"In reality, genetic drift could eventually fix the allele. With a large population size, that's a very s... |
[
"Do aerodynamics matter in the vacuum space?"
] | [
false
] | Other then getting my craft though the atmosphere and into space, could I realistically have an odd shaped craft? And it fly correctly? | [
"To some extent it doesn't matter. However there are still some orbital perturbations which can cause issues:"
] | [
"asteroids, moons, and planets, are not exactly aerodynamic, and they move through space incredibly fast along fairly regular paths.",
"Space is virtually empty. There's no matter to push through. As long as your thrust is aligned with your center of mass you'll fly relatively straight as (there's a lot of orbit... | [
"In space flight, the thing that matters is weight and balance, rather than aerodynamics. Unless you want to rotate your craft, the thrust vector must pass through your center of mass. If it doesn’t, you’ll go spinning off every time you light the engine.",
"A lovely example of a craft designed knowing that it do... |
[
"If a photon is massless can two be in the same place at once?"
] | [
false
] | Since one set of mass cannot occupy the same space as another can photons? Since they have no mass. | [
"Mass is not what limits the occupation of the same space. Particles with mass can actually be all in the same place at once (Bosons can do so with all particles in the same quantum state and fermions can in different quantum states (aka electrons) )"
] | [
"No two electrons can occupy the exact same ",
" not energy ( there was a bit of a complaint by some over the guy who said this on tv). This just means that no two electrons can be in the exact same place at the exact same time with the exact same energy and the exact same spin.",
"If you look at it very broad... | [
"Fermions too, if they have different spins. "
] |
[
"If we had the capabilities to catch up with light that left Earth at a specific time could we see into the past?"
] | [
false
] | null | [
"A green alien living 2000 light years from us is just watching what happened on earth 2000 years ago. An alien less than 50 light years could even theoretically watch our television broadcasting. ",
"But thanks to the fact that nothing can travel faster than the speed of light, you cannot catch up with the light... | [
"I guess I didn't clarify what I meant. :( I know that a planet x amount of light years away would be seeing Earth as it was that far back.",
"My question was more, IF we ever were able to go that fast, could we on purpose calculate where to be to witness a particular time frame."
] | [
"Yes, sure, you could. But that's a big if. Probably the most forbidden if in physics."
] |
[
"Where do the emitted photons go when we switch frames for a charged particles falling in a gravitational field?"
] | [
false
] | There is a (solved) paradox in general relativity of what happen to a . Here is the issue: a charged particle moving under the influence of gravity alone is "weightless", so it shouldn't emit any radiation. But classically we would assume that the charge is accelerating and emitting radiation, from a non-inertial rest ... | [
"But I am bothered by the idea of real photons being emitted by the charge in one frame but not in another. Real particles should exist in all reference frames.",
"that's actually pretty reasonable and in fact definitely a real thing.",
"This is related to how you derive Unruh/Hawking radiation.",
"The existe... | [
"The existence of particles (classically, radiation) is dependent on the observer / coordinate system. ",
"This really is the key to the whole question. In addition to the paper you listed, I also found ",
"this paper",
" to be useful when I was trying to understand this exact same problem. The gist is that w... | [
"If our definition is based on the detection of photons, then we need to take into consideration both the source and the detector.",
"Thanks, that actually helps a lot."
] |
[
"On a chemical level, why are tobacco plants more cancerous than cannabis when smoked?"
] | [
false
] | Or could it be related to the typical amount smoked of each respective plant? | [
"AFAIK, they are not. ",
" smoldering bit of plant/organic matter creates hundreds or even thousands of carcinogens, and other toxic substances. E.g. polyaromatic hydrocarbons (PAHs), just to mention one class of compounds. This is an unavoidable consequence of the fact that there's incomplete combustion going on... | [
"The actual scientific findings on the question of whether marijuana causes cancer are widely distributed and, overall, inconclusive. Smaller case-control studies (",
"this one from New Zealand, 2008, with 403 subjects",
" and ",
"this one from Tunisia, 2006, with 337 subjects",
") show an increase in lung ... | [
"All this is correct. The reason there are no recorded cases of lung cancer from cannabis is that nobody smokes anything close to 20 joints a day 7 days a week, while many cigarette smokers consume this much. There is also some evidence that the greater expectoration induced by cannabis helps remove carcinogens fro... |
[
"Does working out after consuming caffeine make the effects of caffeine wear off faster?"
] | [
false
] | [deleted] | [
"The opposite is actually true",
" in that splanchnic circulation decreases during exercise. To increase blood flow to the muscles being worked, that blood flow has to come from somewhere. Resistance to the muscles decreases while resistance to non-necessary (at the time of exercise) increases to maintain systemi... | [
"Before. Caffeine has some demonstrated analgesic effects. I can't seem to find the specific study I'm looking for, but ",
"this one",
" discusses the topic. The study that I can't seem to find found that people who received 200mg of caffeine prior to cycling could perform for longer before feeling leg pain and... | [
"I'm interested in this as well, as I never know whether to drink my supercaffeinated wake-up of the afternoon before or after my daily bicycle trip."
] |
[
"Where exactly does the boundary lie between Quantum and Classical physics?"
] | [
false
] | Is there a definitive size or something where particles stop behaving by quantum rules and are reintegrated into the world of classical physics? Or am I on the wrong track thinking of it in this way? Edit: Thanks guys, great answers! This really helped my understanding. | [
"Consider the ocean. When you're near it, you notice the waves and the movement of the water, etc. When you view the ocean from far away, it looks relatively still. ",
"That's the difference between Quantum and Classical. Particles never stop behaving with quantum rules, you just don't notice it from up here.",
... | [
"It's not a hard cutoff, but a smooth transition. With bigger and bigger objects quantum effects become less and less noticeable until eventually you can approximate everything with classical mechanics. ",
"I know they've done the double slit experiment with buckyballs, which are about a nanometer big and compris... | [
"I suppose you might want to look for where the action of your system gets much, much larger than h-bar. Then the path integral becomes classical in the stationary phase approximation.",
"Not sure how to explain this without the math, though..."
] |
[
"Has cancer always been this prevalent?"
] | [
false
] | This is probably a vague question, but has cancer always been this profound in humanity? 200 years ago (I think) people didn't know what cancer was (right?) and maybe assumed it was some other disease. Was cancer not a more common disease then, or did they just not know? | [
"http://onlinelibrary.wiley.com/doi/10.1002/ijc.1571/full",
"http://progressreport.cancer.gov/doc_detail.asp?pid=1&did=2009&chid=93&coid=920&mid",
"Short answer: No. Its prevalence has increased. ",
"Longer answer: Compared to 200 years ago, the incidence of cancer has increased. This is due to a combinat... | [
"As the life expectancy has grown longer, cancer rates have increased just because 200 years ago a significant proportion of the population wasn't around long enough to get cancer",
"In addition to this entirely correct statement, it must also be noted that there are more possible sources of cancer in today's wor... | [
"As the life expectancy has grown longer, cancer rates have increased just because 200 years ago a significant proportion of the population wasn't around long enough to get cancer",
"In addition to this entirely correct statement, it must also be noted that there are more possible sources of cancer in today's wor... |
[
"Cetacean experts: Wikipedia alludes to the possibility that dolphins can transmit actual images of their surroundings to other dolphins using ultrasound. To what extent is this true?"
] | [
false
] | This is in addition to dolphins' well established use of ultrasound for 'personal' navigation. The interesting idea here is that they might be able to beam visual representations of objects to other individuals. Could we intercept and decode these messages and obtain a dolphin's mental picture of an object that it has ... | [
"Whether or not it's true, that press release isn't a reliable source, so I've removed it from both the ",
"Ultrasound",
" and ",
"Dolphin",
" articles. If anyone here knows of peer-reviewed research that makes the same claim, that will be another matter…"
] | [
"Well the way they describe it makes more sense than the description of an image.",
"Sonar, in a way, is a translation of an image in terms of sound reflected off of a surface.",
"designed an experiment in which he recorded dolphin echolocation sounds as they reflected off a range of eight submersed objects, in... | [
"Try the email addresses at the bottom of the press release. It says you can get full results that way."
] |
[
"Why do molecules tend towards lower potential energy?"
] | [
false
] | The whole reason chemicals react is to be at a lower state of potential energy. Why is it this way? What's so special about having less potential energy? | [
"No, there isn't. Things try to minimize this quantity we call energy, and that's all there really is to it. You can try to go a bit deeper with the Principle of Least Action, but that's just another optimization problem, except instead of energy we're dealing with a different physical quantity we've decided to n... | [
"The second law of thermodynamics says that a system at equilibrium tends to exist in a state of maximal entropy. This is equivalent to saying that the appropriate energy function (internal energy, Helmholtz free energy, etc.) is at a minimum.",
"This is because the energy within the system is spread around evenl... | [
"The second law of thermodynamics says that a system at equilibrium tends to exist in a state of maximal entropy. This is equivalent to saying that the appropriate energy function (internal energy, Helmholtz free energy, etc.) is at a minimum.",
"This is because the energy within the system is spread around evenl... |
[
"I had to break a spider's web to get to my door. I then watched as it went up and down the leftover web strings and gather them all up in ball. Why did he do this? Can he \"re-use\" the string?"
] | [
false
] | null | [
"Some spiders will gather their webs and eat them on a daily basis. Since spider silk is a fairly protein-rich substance, the spider can subsist off of it until prey is caught. Since you broke the web, it was no longer of any use as a trap. The spider collected it, ate it, and will produce another."
] | [
"Follow-up question: Are there any non-spider species that consume spider webs for the nutrients?"
] | [
"Yes, and how most mammals will eat the placenta after birth. Nutrients saved are nutrients earned."
] |
[
"Why Does a Magnet not repel itself?"
] | [
false
] | I have 2 pretty strong magnets if front of me. They are the size of bottle caps. I have them interact with each other and wonder where the north and south poles might be. I think the south is in the center of the magnet and the north takes the rim... any confirmation on that? Anyway, if south repels south with two m... | [
"To have an \"only-south\" magnet is called a magnetic monopole...and they don't really exist. Scientists have ways to sorta make fake ones, but honestly, it only works ok, not really good enough to do much with.",
"You magnet does not explode apart because if you were to magnify down to the lattice of atoms, you... | [
"You seem to be suggesting that the interaction between two parallel dipoles is always attractive. It actually depends on the angle between the shared dipole moment and the displacement between the two dipoles. If the displacement is perpendicular to the dipole moment, you get a repulsive force. And if you split a ... | [
"'Quick' overview of magnetism:",
"A steady electric current produces a magnetic field---this is a pretty central concept in an introductory E+M course (although this isn't quite the whole story, once you take relativity into a account---briefly, magnetic fields and electric fields are the same phenomenon seen fr... |
[
"Why don't new microscopic life forms spontaneously appear on Earth?"
] | [
false
] | I saw this stupid creationist video on youtube sarcastically asking why we don't find new life in peanut butter jars now and then. I rolled my eyes and then... well.. hey yea why not? Or at least somewhere on Earth at some point in history? Why is it that everything evolved from one single life form rather than two or ... | [
"Good list. #4 is likely the most relevant."
] | [
"Mostly because it takes an incredible coincidence of circumstance to create life randomly out of a collection of, say, peanut butter. Remember that there were a billion years of earth being around before that perfect storm of coincidences took place. A ",
". Humans have had the scientific ability to identify s... | [
"Who's to say they don't? It's obvious why they don't appear in specific places, like peanut butter jars, but to say that, in every nook and cranny on Earth, from the tops of the highest mountains, to the depths of the deepest trenches, some form of abiogenesis isn't happening? That's quite a claim.",
"If it's ha... |
[
"What is the name of the theory that states that the universe is perceivable by us because we are a part of it?"
] | [
false
] | I know I'm not forming my question very well but I just have a vague idea of the concept and I really want to learn it because of a discussion I am having with a friend. Cheers | [
"The anthropic principle doesn't mean quite that. It means that the fact that the Universe has what appears to be the just right, Goldilocks-esque conditions for life to develop - gravity isn't too weak for galaxies to form, the Universe isn't heavily curved so that it quickly recollapses, etc. - is because if it d... | [
"http://en.wikipedia.org/wiki/Anthropic_principle",
"I think this is what you mean. The issue of what \"because\" means gets slightly mindfucky."
] | [
"Perhaps the ",
"Anthropic principle",
"? Maybe you can rephrase your question because you might be referring to something else."
] |
[
"If our cells can respire anaerobically, why do we die (so quickly) when suffocated? Wouldn't the cells just start respiring anaerobically until oxygen was re-supplied so the lactic acid could be broken down? I'm assuming here that all cells can respire anaerobically like muscle cells can."
] | [
false
] | null | [
"Anaerobic respiration is nowhere NEAR efficient enough to do anything more than handle short term emergency situations.",
"When relying on anaerobic respiration, your average cell will break down a molecule of glucose for a net total of 2 molecules of ATP (the energy molecule of the cell).",
"Using aerobic res... | [
"Your brain needs oxygen and glucose and gets a lions share of the blood supply. Without circulation your brain starts to die, generally speaking brain cells start to die after 6 min. So not all your cells are equally capable of anaerobic metabolism. You don't want lactic acid in your brain. I and on my phone so ex... | [
"Every cell in your body can respire anaerobically. Brain cells do it just as efficiently as muscle cells do.",
"The fact is NO cells can do it efficiently, anaerobic metabolism just is not efficient no matter WHAT tissue you are talking about.",
"It just so happens that brain cells are one of the the least ab... |
[
"How does running on a treadmill compare to running on a street?"
] | [
false
] | I've always wondered how treadmills relate to real running, since your body on a treadmill is staying in one place. I can only see that energy expenditure would come from the bobbing up and down as you run, and your legs moving. You are not really propelling your body forward at all. I understand that the carpet moves ... | [
"Don't discount the movement of the air around the runner. By this I mean there is little air movement when you are on a treadmill, while running outside there is plenty of air movement. This means two things: 1) there is increased wind resistance outside versus inside, and 2) the lesser air flow means less cooling... | [
"Obviously running on a treadmill is not just bobbing up and down. Compared to a fixed point on the belt, you are propelling yourself forward. Imagine just jumping up and down with your feet together, you would move backwards and be flung off the treadmill. Imagine running on a train. Whether the train moves or not... | [
"The lack of wind resistance, while small, will make running on a treadmill easier. Also, unless you're running on a track, uneven pavement, roots and other obstacles will make running outside that much more difficult."
] |
[
"When we dream, do we dream in \"real time\"?"
] | [
false
] | Is dream time faster or slower than the perceived speed of time while awake? Could the speed of time that you experience in dreams vary between people or even dreams individually? Is this even possible to measure? | [
"I'm not saying it would be impossible to measure someday, but it's certainly not in reach right now.",
"Think about the experiment you'd have to do. One way to interrogate people's mental experiences is simply to ask them -- self-report. Only problem there is, you'd have to wake the person up first, and there is... | [
"I would agree that imaging is the way to get a real answer.",
"There are, however, a few more pieces of evidence already. They are not conclusive. One study woke subjects after they had been in REM sleep for 5 or 15 minutes and made them guess how long it had been.",
"http://psycnet.apa.org/journals/xge/53/5/3... | [
"Nice reply and interesting links. Of course I bow to your more specific expertise, but I think the first study and OlderThanGif's question below more address the question of \"Can people judge how much real time has gone by while they were sleeping?\" whereas I interpreted the question more like \"If events happen... |
[
"How do we know for sure that there is molten lava in earth’s core?"
] | [
false
] | null | [
"Earthquakes and some other events like nuclear weapon explosions set off seismographs. These record the pattern of the ground waves that reach it. Earthquakes create 2 different kinds of waves which travel at different speeds. Sometimes the direct line from the seismograph to the event goes through the earth. When... | [
"Like some previous folks said it's all about seismicity and earthquake waves. You can read plenty about ",
"seismic shadows",
" on Wikipedia, but basically...",
"Two of the faster traveling seismic waves produced by earthquakes are P-waves (planar waves) and S-waves (shear waves). When an earthquake happens ... | [
"Just to add to your already good answer, the BGS website explains the different waves and how they travel through solid and liquid parts of the earth well: ",
"https://www.bgs.ac.uk/discoveringGeology/hazards/earthquakes/StructureOfEarth.html"
] |
[
"Why do children not spread covid as well as adults ?"
] | [
false
] | With schools opening up in the UK , the government are saying the science is saying, transmission rate among children is low. Why is it low for children and not adults? Why is this getting downvoted... | [
"Conflicting reports of what happens with children. Signs and evidence seem to point that COVID has no preference and will attack anyone equally. Kids may be more susceptible because they are around eachother more and may not practice proper hygiene during a pandemic because they're kids and we were all stupid when... | [
"\"Science\" is not a monolith. Various studies have had conflicting results. Early in the pandemic there was evidence suggesting kids may not spread the virus as much. Now there's evidence that they do. Children in general tend to shed a lot of virus, so we might expect that to be the case here too. The more time ... | [
"Kamikaze... Divine wind?"
] |
[
"I watched an interview with Neil deGrasse Tyson where he says that black holes can evaporate and leave behind everything they consumed. How do we know this?"
] | [
false
] | [deleted] | [
"I started to type up a response but I remembered RobotRollCall had answered this in the past so I'll quote her",
"Hawking radiation is not yet fully understood. It's known that black holes must have a temperature, and anything with a temperature must radiate. These are facts rather than theories; the details of ... | [
"We haven't observed it from black holes, but there have been observations of Hawking Radiation from gravitational analogues that support the theory. ",
"Link"
] | [
"We've never directly observed it. It's a purely mathematical construct that seems to work."
] |
[
"How does the nervous system \"route\" signals?"
] | [
false
] | If you look at a picture of the nervous system, you have the brain connected to the spinal cord, which then branches off to every other part of the body. If the spinal cord is the only signal outlet from the brain, how does the brain signal only a specific organ, such as a single muscle in my hand? The spinal cord and ... | [
"The nervous system is in fact much like a bundle of wires. Nerves are organized in a ",
"hierarchical structure",
" with the individual neurons wrapped in myelin (which insulates the neurons from each other), then the endoneurium (which isolates neuron bundles), then the perineurium (which isolates terminal ne... | [
"I thought I could add another perspective. The other comments have mentioned that indeed, the spinal cord and peripheral nerves consist of bundles of neurons. ",
"However, the story is obviously more complex than that. There isn't a single 1-1 connection from your brain to each individual muscle. There are in fa... | [
"Your first theory is correct, your spinal cord as it leaves the brain is made of several thousands of nerves which you can think of as biological wires so your spinal cord is actually a really thick bundle of wires. As it leaves the brain, the spinal cord is 1/2 an inch thick but a nerve is anywhere from 0.2-20 mi... |
[
"Is it the actual bone itself breaking that delivers pain, or the shards of bone cutting into nerves and muscles that causes pain? Both?"
] | [
false
] | I'f you take away all the muscle and nerves from around a bone and you are left with just an exposed bone and sever it, causing a fracture, will pain ensue? | [
"A little googling turns up this:",
"Yes, a person's bones do have pain receptors. Periosteum is a tissue layer over the bone. The number of pain receptors per square millimeters of Periosteum is greater than anywhere on the body.",
"which entirely explains my own experience where in a very thin fracture that w... | [
"Medical student here. \nYes, the periosteum contributes to the pain of fracture. However, bone is actually extremely vascular and well innervated. You would be in severe pain if the periosteum were absent and you fractured the bone. \nThis is in contrast to cartilage, which is completely devoid of any blood or ner... | [
"So are you saying that it's possible to fracture/break a cartilage and not be aware until much later?"
] |
[
"If swelling is an evolutionary response to bodily injury, why do we attempt to minimize it?"
] | [
false
] | As the acronym RICE suggests, icing a sprain is a crucial part to keep down the swelling. Wouldn't it be better for our bodies to let it swell? | [
"I'm no expert by any means, but in my mind, if you take swelling to be an evolutionary response, then we should take the context back to when the swelling response appeared. ",
"Since swelling is a common occurrence across species, it should be safe to assume that swelling has been around from very early on. As ... | [
"Inflammation is a normal response to tissue injury. A part of this is pain and swelling, so as you say, it is possible that damping down this response may delay healing. I don't know about ice, but there is some evidence that using non steroidal anti inflammatory drugs (such as ibuprofen) can delay fracture healin... | [
"An illustrative (and extreme) example might be ",
"compartment syndrome",
", most commonly caused by trauma. ",
"Basically, your muscles (especially in your arms and legs) are surrounded by fascia, forming separate compartments. Fascia is inflexible, so swelling within a compartment cannot expand the fascia.... |
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