title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"So on the front page is a post about oil being able to completely cover an area of water with a one molecule thick layer. For large industrial oil spills, how does this layer affect the absorption of carbon from the atmosphere?"
] | [
false
] | I've got to imagine that a large oil spill would literally cover hundreds of square miles if the oil is distributed as a one-molecule layer. Considering how often this happens, does it contribute to climate change, or is the effect relatively neutral? | [
"I don't know the answer to your question, but here's a related and interesting issue:",
"I know someone working on a mine pond reclamation project for his master's thesis. The \"lake\" that he studies has a (more-or-less) permanent oil layer on the surface, which (as shown in the YouTube videos) severely dampen... | [
"Even a large oil spill can only cover a fraction of a fraction of the ocean surface, so the effect of any spills on the global carbon cycle is neglible. It is definitely a bigger problem in enclosed water bodies, as ",
"u/maedhros11",
" mentioned. Oil spills cannot cover the entire ocean surface as a one-molec... | [
"This is completely tangential to the original question, but in the days of yore, one of the techniques for dealing with heavy seas when in a small boat was to release oil into the water on the windward side of the vessel. This would dramatically dampen the waves, thus increasing the likelihood of survival for the ... |
[
"How portable can we build CO2 scrubbers to be?"
] | [
false
] | I encountered in (which, admittedly, I only glanced through) and I began thinking of how portable can CO2 scrubbers become. Having worked aboard a submarine for a few years, I only have a passing familiarity with scrubbers. But would it be possible to equip them aboard automobiles and other vehicles? Now I don't only m... | [
"I found a diagram of the scrubbers found aboard subs. ",
"http://www93.homepage.villanova.edu/michael.b.walsh/CO2Scrubber.htm",
" ",
"Now I have also been reminded that we used, in addition to the scrubbers, CO/CO2 burners. Would these have any adverse effects to emissions, if they were manufactured for port... | [
"I found a diagram of the scrubbers found aboard subs. ",
"http://www93.homepage.villanova.edu/michael.b.walsh/CO2Scrubber.htm",
" ",
"Now I have also been reminded that we used, in addition to the scrubbers, CO/CO2 burners. Would these have any adverse effects to emissions, if they were manufactured for port... | [
"They can be very portable, for example, ",
"Closed-circuit rebreather",
" diving systems all contain a CO2 scrubber. These systems allow divers to stay underwater for extended periods. ",
"However, using them for the purposes you are mentioning isn't likely because there will always be a cost to build them, ... |
[
"How close does the energy of a photon have to be to the energy jump of an electron for it to absorb the photon?"
] | [
false
] | If an electron can only absorb all or none of a photon and can only jump up to specific energy levels, the energy of the photon would have to be equal to the energy level of the electron. But, I am assuming that there can be some error, otherwise it would rarely happen. What is this error and why is there one? | [
"The answer is if you are going to transition between two bound states (energy levels) the energy of the photon and energy of the transition must match ",
" for non-scattering interactions.",
"That being said its not \"rare\" because we are typically measuring ensembles of many many atoms. These ensembles have... | [
"I think they may have a misconception about the photo electric effect. Like dirac said, the probability is a distribution such that probability that a specific photon with energy E will undergo this interaction with a nuclei of an element with Z protons is proportional to Z",
" It is much more prevalent with hig... | [
"They weren't talking about the photoelectric effect at all. The OP discretely mentioned transitioning energy levels (i.e. bound state absorption), while the photoelectric effect operates [roughly] in a continuum when above the disassociation energy. When you see someone mention jumping to an energy level, 99.999... |
[
"If weightlessness in orbit is due to free fall and not lack of Earth's gravity, then is there weight in space on trajectories? I.E. traveling to the moon?"
] | [
false
] | null | [
"It's not an \"orbit\". It's an orbit. It's highly eccentric, but it's not like it's going to escape orbit or something. It's not called the Hohmann Transfer ",
" for nothing."
] | [
"Yes. A spacecraft in a Trans-lunar trajectory will be ascending in Earth's gravitational field, gaining potential energy. While it does so its speed will gradually decrease due to the gravitational pull. So gravity is still pulling from the spacecraft.",
"I understand if you want to choose a different name for t... | [
"There would be, if the space ship got to the Moon by pointing itself at the Moon and going in a straight line. Then, until you were really quite far from the Earth you would feel quite a bit of pull towards the Earth. But, as you might have guessed, that isn't how we send things to the Moon. ",
"When we travel f... |
[
"Why is 0! equal to 1?"
] | [
false
] | null | [
"If you are running a restaurant and during the entire day one person (call them A) comes in for a meal, there is only way your day can play out: \"A came in\". 1! = 1",
"If you are running a restaurant and during the entire day two people (call them A and B) come in for a meal, there are two ways your day can pl... | [
"The answers talking about bijections or convention are correct but I feel that you miss a more general phenomenon :",
"What do I mean by an empty product ? Let's take a concrete example of a product of products :",
"(4x5x9)x(5x123x47)",
"By associativity of multiplication, we can rewrite",
"(4x5x9)x(5x123x... | [
"Perhaps the analogy wasn't perfect, but it corresponds very well to a mathematical reason why 0! =1 , namely k! is the number of ways the elements of a set with k elements can be arranged and the elements of the empty set can only be arranged in 1 way. ",
"A lot of the time the use of 0! boils down to whether or... |
[
"If you slowed down the cooling of glass to a solid, could it form a crystalline structure?"
] | [
false
] | From reading it seems that glass is an amorphous solid because it cools too quickly for the molecules to line up. If you were to slow down the cooling process enough, could it form a crystalline structure? If so, would the properties of the glass change in any noticeable way? | [
"I have done some glassworking in my past and seen what you are imagining. You sometimes see ",
"crystal-like flakes and roughness",
" on the surface of handmade glassware. That's glass's crystalline phase. It is brittle, rough and considered a defect.",
"Usually this is caused by overheating of the surface d... | [
"That sounds very very cool. You don't have any pictures of it do you?"
] | [
"Not quite. Tempered vs annealed glass relates to the amount of internal strain, not whether it is crystalline."
] |
[
"Can lightning be used as a source of energy?"
] | [
false
] | would it be possible to create some sort of massive negative charge between the earth and its atmosphere where lighting happened very frequently? then outfit these "lightning fields" with some sort of device or structure that could gather the energy that the lightning produces? | [
"You're trying to violate the first law of thermodynamics. Lightning doesn't \"produce\" energy. It is a transfer of energy. The energy you could get from the lightning is less than the energy it woulld take to 'create some sort of massive negative charge' in the first place."
] | [
"Triggered lightning has actually has been done with ",
"rockets",
" (turn down volume) but as a reliable energy source is a different issue. You have to store the energy in a bolt that has an electrical potential of millions of volts at kiloamps of current that lasts for tens of microseconds."
] | [
"And also, one single bolt doens't even have that much energy, its just that it goes al at once"
] |
[
"Could you Destroy a Black Hole by feeding it a whole bunch of Anti-Matter"
] | [
false
] | null | [
"No. Adding antimatter or matter to a black hole increases the black hole's mass. In fact, there is no difference between a black hole assembled from a bunch of matter or a bunch of antimatter.",
"The Hawking calculation of black hole radiation does NOT suggest that antimatter going into a black hole decreases ... | [
"Once inside the black hole, the particle's origin as matter or anti-matter is irrelevant. What the black hole keeps track of is the mass, the spin, and the charge, and that's it.",
"Note that even if you imagine a particle/antiparticle collision inside the event horizon, all you are imagining is energy that sta... | [
"Wut.... Quarks are not anti quarks"
] |
[
"Theoretically, can deserts be turned into arable lands?"
] | [
false
] | The question might come off as one better suited for yahoo answers. Nonetheless, I'm assuming that the process of arable lands turning into deserts involves several chemical reactions; if those reactions were to be reversed, can we regain or expand our arable lands? Furthermore, if certain types of bacteria and inverte... | [
"Climate has a lot to do with why a desert is a desert, as most (all?) deserts don't receive adequate moisture from prevailing wind patterns, and that's probably what initiates desertification of a previously non-desert area. Once that has happened though, the biomass, primarily soil, of the area tends to dry up a... | [
"It is possible to reverse desertification, but a lot of it has to do with why it became desert in the first place. A great deal of desertification in modern times has to do with climate change and that no one is routing water into those areas. With enough water and proper soil, you could create arable land nearly ... | [
"Don't underestimate the power of plants to alter the microclimate at ground level. They help to moderate temperature, slow the wind, and raise humidity - making the area much more amenable to life. With time, they also add organic carbon to the substrate, the beginnings of fertile soil. And where going out and pla... |
[
"Dumb Question: How do Lakes and Ponds become populated with Fish?"
] | [
false
] | Have they been there for centuries as the lake got smaller and the water sources stopped flowing? Does evolution in fish happen in these ponds / lakes over the many years? | [
"i remember seeing a similar question - but it was how big puddles of water on mountain tops have fishes. The answer to that was - birds carry them there, some eggs stick to their legs and it fell on these puddles when they fly by and created a small system."
] | [
"\"Evolution\" or at least genetic segregation does occur within lakes. This has been documented with fish in lakes on and near Vancouver island. ",
"Lakes also usually have river outlets so they are connected to ocean. "
] | [
"I don't get why I'm being downvoted for this. It's not a scientific answer, but that doesn't mean it's not true. If it weren't for fisheries restocking them, some lakes would have way less fish, if any. Ask a \"dumb\" question, be prepared for a \"dumb\" but technically right answer."
] |
[
"How do multiple members of the same siphonophore species have the same shape if they are just colonies of individual animals?"
] | [
false
] | null | [
"The same reason you and other animals have the same shape even though you are just colonies of individual cells (after a manner of speaking). The colonies grow from each other in a defined pattern, producing a similar final outcome. ",
"Don't imagine that a bunch of individuals clump together in a random mass ... | [
"What determines the body plan ? Do they have something similar hox genes ?"
] | [
"Animal colonies are made up of multiple physiologically integrated and genetically identical units called zooids that are each homologous to solitary, free-living animals. Siphonophores, a group of pelagic hydrozoans (Cnidaria), have the most complex colony-level organization of all animals. Here the colony-level ... |
[
"Why doesnt the iron in red blood cells rust when it binds with oxygen molecules? And how do red blood cells deposite the oxygen molucules if its binded with the iron in the red blood cell?"
] | [
false
] | Be nice. I have the low end high-school understanding of chemistry and biology. I know why blood cells are able to "carry" oxygen to different parts of the body I just don't understand how they get rid of it or where it goes and how it's used on a molecular bases... But you don't have to answer that last part, I'll le... | [
"Well, red blood cells have the protein hemoglobin in them, which in turn contains ",
"heme",
" groups, which is a big organic molecule with an Fe(II) atom in the middle. So it's not free or metallic iron, it's already formed an iron compound and the iron is already oxidized a bit, and won't react with the oxyg... | [
"I find the control of oxygen-binding by carbon dioxide (i.e., the ",
"Bohr effect",
") pretty amazing. Basically, carbon dioxide binds to hemoglobin and changes the shape of the protein, which in turn makes it easier to release the bound oxygen."
] | [
"Not only that, but heme complexe's actually look like red blood cells, and the entire binding site becomes concave, to literally catch oxygen, and convex once it's bound. It's a truly fascinating little feature of our bodies."
] |
[
"Do animals have a biological way to \"tell time\"?"
] | [
false
] | Every morning without fail my cat will wake me up minutes before my alarm. Is an animal's sense of routine strong enough to know when to do something down to the minute? | [
"Sure they do. I'll answer your question more generally, and not worry about just your cat. Most animals have different priorities at different times of the day. For example, female crickets will hide in burrows during the day, and only move around after dusk when it is safe to search for mates. Male crickets will ... | [
"Basically, crickets have both an internal and external clock, since they have a biological clock that can be adjusted with environmental cues.",
"Awesome information! Can animals adjust their biological clocks without any environmental cues based on the schedules of other creatures? Example being being able to... | [
"I've editid in a bit about the neurobiology of circadian rhythms. I'll add more as I get some breaks lol"
] |
[
"Where can I see the entire human genome?"
] | [
false
] | I remember a poster in school which showed the entire sequence in the black/white lines (I'm sorry, I don't have a clue about the actual name of the methods or anything). Is there anywhere that I can see the entire sequence in this format and is there anywhere that would give some more information on our genetic make-u... | [
"The poster didn't have the full sequence. The Venter group sequenced 2.91 billion base-pairs, and you can see ",
"here",
" a whole bookcase of books with the sequence, each chromosome being several books. And ",
"here",
" you can find ",
" paper about the sequencing."
] | [
"How about ",
"this",
"?"
] | [
"The entire genome is browseable with NCBI map viewer. ",
"http://www.ncbi.nlm.nih.gov/mapview/map_search.cgi?chr=hum_chr.inf&query"
] |
[
"Can insects “heal” from injury like animals do?"
] | [
false
] | If I try to smush a spider, and mostly miss but still manage to cause a little bit of damage, will the spider be able to heal from said damage? (I’m being ambiguous about what the damage is... I didn’t want to restrict what the answers might be!) | [
"Though importantly, most insects (unlike spiders) have determinate growth and do not molt any more once they reach adulthood, so they can't really do much at that point."
] | [
"Though importantly, most insects (unlike spiders) have determinate growth and do not molt any more once they reach adulthood, so they can't really do much at that point."
] | [
"Depends on the kind of injury, and whether we're talking about insects or spiders. Spiders can heal exterior injuries quite well, up to and including regrowing lost legs; they molt (shed their skin) regularly, and with each molt, any lost parts of the exoskeleton (including entire legs) can be replaced, although t... |
[
"Asteroid A/2017 U1 may be the first interstellar object to be observed to pass through our solar system. If we had had more warning of its arrival, could we have sent a probe to it? How much warning would we have needed?"
] | [
false
] | I'm curious if such a mission is possible using current technology, given the object's unusual trajectory and high velocity. | [
"It's very small, and going really ",
" fast. It came close enough to Earth's orbit that sending a \"flyby\" probe would be conceivable: basically you could send a probe out to where it's going to be, and let it zip right past you. But as ",
"/u/katinla",
" says, matching orbits for a rendezvous would be im... | [
"Sending a probe to an asteroid is no longer a utopia since Rosetta successfully did a Rendez-Vous with comet 67P. But it was relatively easy because it was in a low speed orbit around the Sun that doesn't get too far away.",
"We would need years of warning, which we didn't have for A2017 U1 and we're unlikely to... | [
"If you were just going to do a flyby, no plane changes, where your probe meets a/2017 u1 at the probes apogee, you could do it with a Rosetta or less mission. The object came within 60 times the distance of the moon to the earth (roughly 23064000 km), and the delta v for the transfer part of a Hohmann transfer fro... |
[
"Arsenic in food. What's the real story?"
] | [
false
] | [deleted] | [
"The CDC's Chemical Profile page for ",
"Arsenic",
" is a really good place to start.",
"In the US the only exposure levels that have been set are for occupational exposure, by OSHA, and the EPA has set a standard for arsenic in drinking water (0.01 ppm).",
"In general, you probably won't ingest enough arse... | [
"You are thinking of cyanide."
] | [
"He most likely meant elemental arsenic vs soluble inorganic arsenic. The only studies done on organic arsenic have been on animals.",
"One caveat I have of making such a distinction, is most of the time, we don't know what form of arsenic we're being exposed to because it so readily transforms in the environment... |
[
"What is a wrinkle? How do wrinkles look different at cellular level compared to smooth skin?"
] | [
false
] | [deleted] | [
"People get wrinkles as they get older due to a decrease in collagen production in the dermis layer of skin. In addition, collagen is also broken down faster by the body. This leaves the person with a lack of volume in the dermis, and epidermis will sink and wrinkle as a result. Dermal fillers, used in plastic surg... | [
"Well that's one way, however generally supplements are mainly cons. However having added potassium can help. A big factor can be to try and keep out of the sun, and drink water! Fluids help lots with the skin."
] | [
"Skin is extremely flexible and has enormous tensile strength. This is due to proteins and the cellular composition of skin. However skin cells need a good blood supply and therefore minerals and water- achieved through active transportation, diffusion and osmosis.Also skin contains elasticin and collagen which pro... |
[
"Can humans die due to being in water for too long?"
] | [
false
] | Discussing ways a human could die, my friend asks me if a person could die for staying in water too long. Could a human stay in a body of water(oceans, rivers, pools) for too long for it to become fatal? What if they were to receive constant food and water? | [
"I seem to recall a study finding that pruning was actually the result of our epidermis responding to the wet environment to gain more traction... I'm on mobile or I'd track it down, sorry :/"
] | [
"I seem to recall a study finding that pruning was actually the result of our epidermis responding to the wet environment to gain more traction... I'm on mobile or I'd track it down, sorry :/"
] | [
"Human bodies just aren't made for prolonged submersion in water. I don't know exactly how long it would take to impact your health but ",
"this gentleman",
" apparently spent over 50 hours straight underwater, although granted he was wearing dive equipment. Besides any ill effects that you might experience f... |
[
"Why have we evolved to have compassion at the levels we have?"
] | [
false
] | As humans have matured, it seems that compassion has become more and more prevalent in our species. This to my mind seems to go against the "survival of the fittest" principle of evolution I imagine it increases the chances of survival (and therefore procreation) of the not-fittest. Now I am not condoning neither am I ... | [
"Compassion is a feeling that falls under empathy - empathy, or putting yourself in the shoes of others - can be very helpful evolutionary speaking. If compassion leads you to care for others (sick, wounded, poor...) you may increase their chances of survival. If they are close kin this falls under the kin selectio... | [
"From a purely game theoretical standpoint, it can be argued that compassion arises from the prevalence of ",
"cooperative games",
". Individuals that are better able to cooperate when \"playing\" such games are often more fit.",
"You may be interested in exploring the relevant field, ",
"Evolutionary Game ... | [
"Ironically my degree was in Artificial Intelligence and Computer Science and one of my courses was evolutionary computing :)",
"What you say is certainly true for a certain level of compassion, but I should think that if the compassion gets past some threshold, to the point that it is reducing the ratio of fit t... |
[
"How much ice would we have to mine from the moon to make cargo missions to resupply water to the ISS economically viable?"
] | [
false
] | [deleted] | [
"It's actually simpler than you think. ",
"Gerry O'Neill",
", an early proponent of space colonization (see ",
"this",
") realized that you don't need rockets to launch material from the Moon. He proposed to use magnetic launchers. The big expense of lunar mining is the need to maintain a presence at th... | [
"This might work. However, trying to run an industrial operation with minimal cost is not the same as running a scientific experiment. Mining is dirty, and equipment requires maintenance and repair."
] | [
"This might work. However, trying to run an industrial operation with minimal cost is not the same as running a scientific experiment. Mining is dirty, and equipment requires maintenance and repair."
] |
[
"When putting her to bed last night, my daughter (7) asked me to get her \"a science book, and a book about space!\" Any recommendations to nurture a budding 7-year old scientist, reddit?"
] | [
false
] | null | [
"When I was that age (and as I got older), I loved looking at books with lots of pictures and little blurbs covering a variety of topics and using that as a jumping off point when something in particular struck my fancy. I would suggest going to a local book store and looking at some of those big, glossy coffee tab... | [
"Is eyewitness still around?"
] | [
"+1\nI had one of those hard cover A3 sized books with plenty of pictures and covered a variety of topics from space to precipitation to light to electricity etc. All explained in a page or two then next subject. Kept my young wandering mind focused and curious"
] |
[
"Did National Socialists' program of euthanizing the mentally ill have lasting impact on mental retardation rates in Germany?"
] | [
false
] | I'm wondering where I can find data on this. Cross-country analysis on mental retardation rates would be particularly interesting. | [
"I don't know the statistics, but from what I do know about mental retardation, I would have to say it is unlikely to have had a huge impact. Some developmental disabilities can be hereditary, but for the most part they are random genetic anomalies (like down syndrome can be) or injuries to the brain (from prenatal... | [
"Just to add to the excellent observations from others:",
"If mental disability has a genetic cause (and it's not due to, say, nondisjunction), it's likely to be recessive. This is an oversimplification; for example, mutations in the same part of chromosome 15 can cause either Prader-Willi or Angelman syndrome de... | [
"hmm, to me it seems like grandtheftautumn just doesn't have any statistics to cite and instead contributed some useful, valid observations."
] |
[
"I met a man denying that we ever went to the moon. His main argument was that the astronauts would have died passing through the Van Allen belts. Does this claim have any truth?"
] | [
false
] | I know we dont know how much about the Van Allen belts but from some reading I found that a satellite in that region is exposed to 25 Sv in a year which is about 3 mSv an hour which if i remember correctly is pretty high, but not enough to kill, maybe increase risk of cancer. He also claimed that solar/gamma rays would... | [
"Correlation is evidence."
] | [
"Correlation is evidence."
] | [
"No one is interested. Please stop entertaining idiots like the one you've met."
] |
[
"Is it possible that we as a species of this planet are missing out on a sensation because of our environment and/or anatomy?"
] | [
false
] | For example, imagine an alien race that doesn't have the ability to hear anything (for whatever reason), yet we know that under the right conditions, sound exists. | [
"Absolutely, there are many things that humans can't sense that other animals can (and we don't even have to leave earth to find them). For instance, some animals can sense magnetic fields (some birds and insects) and some can sense electric fields (many fish) ",
"(Source)",
". ",
"In addition, you can also c... | [
"Just to add to this. ",
"There are also lots of senses that humans have that we don't necessarily realise. The 'five senses' we are taught about in school are a grand oversimplification. Touch, for example, is not just one sense; we have multiple pain senses, both hot and cold temperature, fine, deep and vibrat... | [
"This is a bit of an oversimplification. A lot of creatures would be MORE successful and more able to survive as a species with other adaptations that they don't have now, without potentially endangering the entire species through resulting overpopulation. ",
"One example is the ability to swim or fly longer dist... |
[
"How can I interpret c^2 or v^2?"
] | [
false
] | It is hard for me to visualize this concept. I can visualize velocity and I can visualize acceleration. However, I cannot visualize a squared velocity. What does that even mean? When you consider the formula F = ma, this makes perfect sense to me because that just means mass at an acceleration. But e=mc means mass at a... | [
"e=mc2 means mass at a what?",
"E=mc",
" means the energy of mass at rest. The ",
" in this equation is the square of the speed of light, but ",
" is much more than just that. What Einstein really discovered in Special Relativity was that the universe does not exhibit what is known as ",
" in which there ... | [
"I don't think that the general concept of \"velocity squared\" really means much. You never solve for it, for instance. In K=1/2 mv",
" , it just means that doubling the velocity quadruples the energy and so on.",
"I think it would be better to think in terms of W=Fd and Joule = Newton ⨉ meter, if you want a m... | [
"I'm not physicist, but I can give a quick answer, and maybe someone else will come along and give a better one.",
"First thing, e=mc",
" wasnt just written down out of no where, it was derived from other equations. Indeed, it is a result that can be derived in all sorts of ways, including one of my favorites j... |
[
"What is the physiological basis for crying after being presented with emotional stimuli and is it shared by other species?"
] | [
false
] | null | [
"To the first question, there are two answers. The first is that the tears released when crying* contain manganese and the hormone prolactin, lowering the quantities of these chemicals in your body. Since these are the chemicals that are responsible for our emotional stress, lowering getting rid of them can make yo... | [
"Here are some articles about this",
"http://www.independent.co.uk/life-style/health-and-families/features/how-crying-can-make-you-healthier-1009169.html",
"http://www.healthylifect.com/mind/article/The-science-behind-your-tears-582550.php",
"http://lifestyle.iloveindia.com/lounge/why-does-crying-feel-good-23... | [
"Cite this please."
] |
[
"[CS] Developers, how is \"corrupted\" text (e.g. i̶̶̪̦̼͇͇̞̯͉͡ŕ̭̰͕͘ ̳̦̀͟h̀͏̧̮͔̼̠̗̫̯̭̲̜̺̬̗ ̴̷̡̫͎̟̦̠̞͡f̶̝͕̞͇̳͚̩̹̖̦̭̙͜͡) created and displayed?"
] | [
false
] | [deleted] | [
"Those ",
" unicode symbols. Unicode includes all sorts of complicated things beyond ASCII's simple assumptions that one symbol follows another from left-to-right. It supports ligatures (combinations of characters), scripts written in both horizontal and vertical directions, character rotation, characters whose... | [
"In Unicode, there's a class of characters called \"combining characters\" which mark over multiple letters. An unlimited number of these can be used to mark certain letters or letter combinations.",
"The way these things work is by taking a few letters and then adding a shit ton of combining characters until th... | [
"They are allowed to exist because they are technically valid. If you put spaces between the letters and zoom in or start deleting them character by character with backspace, you can see that the first example is just regular text with too many diacritics, while the second are some special characters, also with man... |
[
"There seems to be a disagreement between magnetic north as indicated by three compasses and maps that depict my house"
] | [
false
] | I was looting my closet today and found a couple of magnetic needle compasses and when I checked the first it seemed to be off by about 10° I figured it was just old. But then I started looking at a few other magnetic compasses (two more) and they All pointed 10° to the right of North. According to satellite pictures o... | [
"Magnetic North and Geographic North are two different directions. The higher in latitude you are, the more extreme the deviation will be according to a compass.",
"The magnetic pole ",
"wanders about somewhat",
" (at the moment it's heading NE at about 55km per year). If you have a decent quality navigationa... | [
"Magnetic North",
" and true geographic north are not the same. The exact location of the Earth's north magnetic pole wanders somewhat over time, and is currently some seven or so degrees south of the North Pole, located somewhere in northern Canada."
] | [
"There is a difference between true north and magnetic north. True north is the direction from you to the geographic north pole (that is, the point where the axis of rotation of the Earth \"pokes through\" the top of the Earth). ",
"Magnetic north",
" is in the direction where the pole of the magnetic field of ... |
[
"Are all liquids incompressible and all gasses compressable?"
] | [
false
] | I've always heard about water specifically being incompressible, eg water hammer. Are all liquids incompressible or is there something specific about water? Are there any compressible liquids? Or is it that liquid is an state of matter that is incompressible and if it is compressible then it's a gas? I could imagine th... | [
"Liquids are ‘incompressible’ in that they are only slightly compressible.",
"If we set ‘z’=1 where a fluid density doubles for a doubling of absolute pressure at constant temperature, liquids have a ‘z’ between about 0.001 and 0.05.",
"Gasses/vapors typically range from 0.4-1.6.",
"Z is compressibility."
] | [
"All liquids are compressible. You just need much more pressure for a much smaller effect compared to typical gases.",
"If you compress a gas enough (and maybe heat it, depending on the gas) you reach the critical point, a point where the difference between gas and liquid disappears. The clear separation of the t... | [
"It's worth stating that the elementary approach to water flow using incompressible equations is because it's a ",
" good approximation. The difference is nearly immeasurable in most setups."
] |
[
"If I was in a truck that drove of a bridge and managed to jump from the cab, would I initially be descending at the same rate as the truck or would I have started a new rate of descent?"
] | [
false
] | I don't even know if this is the right sub for this, I'm bored in traffic and had this random thought. Edit: if the mods see this and could whack a physics tag on this that would be great, I didn't know how to on mobile. | [
"Since a truck has a lot more surface area than you do, you'd fall faster than the truck as you have less surface area for air to slow your descent.",
"Except, a truck has a lot more gravitational force acting on it to counteract any force due to friction.",
"So, it would depend on the truck.",
"I would imagi... | [
"It has an effect on the gravitational ",
" itself. If there are no other forces, the mass of the object just cancels out when you calculate the acceleration, so it doesn't matter.",
"However, when you're dealing with a real world situation where things like air resistance are a factor, the mass of the falling ... | [
"Technically, you're both right and wrong in your own special ways. At first, yes, the person and the truck will have the same initial velocity, but only for a moment. As they continue to fall, they both feel an acceleration due to gravity of roughly 9.81 m/s",
" however, they do not actually accelerate at this r... |
[
"Does Platanus orientalis (looks like a maple tree) provide a sweet syrup like \"Maple Syrup\" as produced by \"Acer Saccharum\"?"
] | [
false
] | The scientific names are in the question but in case I got them wrong, do the maple trees that grow in Kashmir (referred to as Chinar) produce maple syrup like their look alikes in Canada? | [
"The genus ",
" is only very distantly related to the maples- they're both eudicots, but that is an enormous group of extremely diverse plants; for example, ",
" is more closely related to ",
"water lilies",
" than it is to maples, and maples are more closely related to ",
"poinsettias",
" than to ",
... | [
"Platanus species are not maple trees and aren't even that closely related. That said, blacksheep998 is pretty much correct. You could probably get and distill the sap from them but and it would be sugary, but it probably wouldn't taste the same because the other compounds present would be different. ",
"Accordin... | [
"Maple syrup is simply a concentrate of the sugary sap found in sugar maple trees. All trees transport sugars in their sap, so any tree should be able to produce syrup if you extracted and distilled the sap.",
"The problem is the other chemicals present in the sap. Many, probably most, would taste terrible. And s... |
[
"Why can't we use capacitor as batteries?"
] | [
false
] | Instead of chemical batteries? | [
"Batteries have much higher energy densities than capacitors, so they are used where you need to store a lot of energy. On the other hand, capacitors can be charged and discharged much faster than batteries, so they are used where high power is needed."
] | [
"Chemistry mostly. One is based on storing energy in an electrical field in a dielectric. Batteries are based on electronegativity. ",
"There are designs and products on the market that have both in them. Super capacitors."
] | [
"Batteries are designed so that two chemical plates (electrodes, + and -) create an environment that enables the travel of electrons in one direction and ions (the atoms the electrons separated from) travel in the opposite direction. The good thing is you store a lot of energy, the bad things are your speed of ener... |
[
"Could the event horizon of one black hole be deformed by the gravity of another close black hole?"
] | [
false
] | Or are event horizons usually spherical? | [
"Yes, when they are extremely near each other, the event horizons of two black holes can deform. They can grow \"fingers\" towards each other until they merge. "
] | [
"Once their horizons intersect, there is a process of \"ringdown\" in which the newly formed merger remnant BH event horizon oscillates down to its final form. The solutions interior to the horizon are chaotic and not very friendly. It's unfortunately not as simple as \"we have two singularities and a point of equi... | [
"If their event horizons intersect would there be a locus between the singularities with 0 net gravity between them?"
] |
[
"My cats have eaten the same dry cat food, everyday, for years... Do they mind??"
] | [
false
] | null | [
"Cats have very few taste buds (fewer than 500, compared to over 1500 for dogs, and over 9000 for humans), so I don't think they care all that much. The smell is likely more important to them. "
] | [
"Don't worry evolution will take it's place and fix it. We shall see one more taste bud here soon\nEvolution is science right?\n(downvotes to the left)"
] | [
"Don't worry evolution will take it's place and fix it. We shall see one more taste bud here soon\nEvolution is science right?\n(downvotes to the left)"
] |
[
"Does the ISS need to constantly make micro course corrections to compensate for the crew's activity in cabin to stay in orbit?"
] | [
false
] | I know the crew can't make the ISS plummet to earth by bouncing around, but do they affect its trajectory enough with their day to day business that the station has to account for their movements? | [
"Momentum is conserved in a closed system. People in the ISS can't permanently change its trajectory by moving around. They push off one wall, sending it in the opposite direction but then they must necessarily then hit the other wall, undoing what they did. The center of mass momentum of the station+occupants is f... | [
"Why would a spinning space station experience more drag? Isn't drag the result of atmospheric particles hitting the space station? Wouldn't those particles hit whether the space station is spinning or not?"
] | [
"A different orientation could lead to a larger cross section of the station.",
"The effect of humans on the orientation is completely negligible, however. The ISS orientation is unstable on its own and needs gyroscopes to stay as it is anyway.",
"Edited for clarity."
] |
[
"How is space research done?"
] | [
false
] | I understand the basic principle of an orbiting telescope, using some series of lenses making an slr look like tinker-toys, but how are things like the temperature of the sun, the size and distance of planets, and the shape of galaxy's figured out? | [
"The shapes of distant galaxies are figured out simply by looking at them. They're very far away, but they're ",
" so it's not that challenging to take photographs of various sorts. The resulting pictures are informative, but they're also quite pretty.",
"The shape of ",
" galaxy is inference and speculation,... | [
"The temperature of the sun can be inferred in a variety of ways. One way is to look at the radiation we receive from it and compare it to the spectrum of what's called a ",
"black body",
".",
"The distance of a planet (from the Sun) can be figured out by looking at how it moves across the sky, and comparing ... | [
"In case anyone else is trying to find more information on the mentioned Virgo galaxy, which is rather hard to find because it shares its name with the Virgo supercluster of galaxies, here's a link: ",
"http://en.wikipedia.org/wiki/Virgo_Stellar_Stream"
] |
[
"Why does placing a wooden spoon over the top of a pot of water stop it from boiling over?"
] | [
false
] | . | [
"When the bubbles hit the spoon they go 'POP'"
] | [
"Does this really work, do you have any reference our just personal experience? I guess I will have to conduct some tests.",
"A trick I know work is putting a metal spoon in the pot. This reduces the entropy gradient since it conducts heat. Having a lower entropy gradient means less convection. It doesn't complet... | [
"It doesnt work with steel or metal things"
] |
[
"A bullet is shot and is travelling at 2,500 FPS. As the bullet travels, is the space directly behind it (let’s say an inch) filled with air? Or does the bullet push it aside and there is ‘nothing’ behind it?"
] | [
false
] | null | [
"The nose of the supersonic bullet creates a shock wave pushing the air out of the way, but the tail of the bullet creates an \"expansion wave\" -- basically the opposite of a shock wave -- that allows the air to flow in behind the bullet again. The pressure behind the bullet will be low, but not zero.",
"Here'... | [
"Stability of the bullet is due to the spin of the bullet along the long axis. This stability can be calculated via an empirical formula called the Greenhill formula.",
"Neat fact - you can reduce drag on a bullet with a flat base by bleeding air into the turbulent region directly at the base of the bullet in the... | [
"Here",
" is a similar question asked by someone on stack exchange. The answer given was about 3x higher velocity but still in an idealized sense. In reality you can’t create a full vacuum but the air pressure behind a bullet would be significantly lowered. ",
"The bullet pushes the air out of the way but as so... |
[
"Where did the bacteria in our digestive system come from in the first place?"
] | [
false
] | null | [
"Well, for one, in a minor way, from whatever touches our mouth or gets far into our nose. You can think of the body as doughnut shaped. The dough is where all the organs are, and is bounded by epithelial tissue. On the outside, that's skin, and on the inside it's the esophagus, stomach, intestine tissue, etc. When... | [
"As the womb isn't actually as sterile as everybody previously thought, the first bacteria a human encounters is in the womb. Bacteria have been found in amniotic fluid, in blood the umbilical cord, the membrane around the fetus, etc. "
] | [
"It's ironic that pandas do that. They have the guts of a carnivorous animal\n They're one of the most inefficient animals there is."
] |
[
"How much of the planet was covered in forest before humans, and how much is covered in forest now?"
] | [
false
] | [deleted] | [
"Lots of speculation in this thread, but no actual answers.",
"The best data ",
"from the UN",
" shows that about 3.9 billion hectares of forest are around today, and ~6 billion were before human civilization. We've cut down about a third of the total forest on Earth."
] | [
"It's worth noting that in some places human activity is causing the reappearance of forests. Much of the Eastern U.S. was cleared for agriculture in the 18th and 19th centuries, but now that so much farming has moved to the Midwest a lot of the old farmlands are reverting to forest. Human activity, especially fire... | [
"Forestry management dates back to somewhere between the 5th and 13th centuries depending on how you define it. If you are harvesting trees heavily you immediately grasp the importance if being able to harvest them within a reasonable distance of where they are needed for the transportation you have available at t... |
[
"Is ADHD over diagnosed?"
] | [
false
] | I just saw a report on NBC Nightly News about how so many children are being diagnosed with ADHD. I also commonly hear the layperson saying "It's just kids being kids, the don't need any medicine." Is the rise in diagnoses just from heightened awareness (like I've heard about autism)? Also, 20 years ago my sister was d... | [
"Most studies suggest that 5-7% of children have ADHD. This comes from studies that take, for example, 1,000 children and do comprehensive assessments to determine whether or not they meet criteria for ADHD. However, in the real world about 10-20% of children are diagnosed or treated for ADHD (in the US. The numb... | [
"Of course. Pay close attention to the methodologies used in each study, and how it correlates with the results.",
"http://journals.lww.com/co-psychiatry/Abstract/2007/07000/Epidemiology_of_attention_deficit_hyperactivity.13.aspx",
"http://www.ncbi.nlm.nih.gov/pubmed/18998276",
"http://www.ncbi.nlm.nih.gov/p... | [
"Do the prescribed medicines have side effects?",
"Yes. Hypertension, appetite suppression, weight loss, agitation, anxiety, sweating, headaches, dizziness, insomnia... among other things. ",
"If a child is misdiagnosed, can giving them the medicine mask their undiagnosed mental issues that you allude to in y... |
[
"How dark is outer space?"
] | [
false
] | If you got far enough into space, away from the sun or another star, would you still be able to see your hand in front of your face, or would it be too dark? | [
"You don't even need to leave Earth for it to be that dark. On a moonless night in the wilderness, fifty miles from the nearest streetlights, you can only see your hand by the black hand-shaped void where it blocks out the stars."
] | [
"But this would be due to the earth blocking the sun's light. Out in space far away from anything you wouldn't have this massive rock blocking light from hitting at all angles, even with how minimal light there would be I would feel you could still see your hand"
] | [
"I think the question here is: if you were in interstellar space, would the stars provide enough light for you to be able to see anything? "
] |
[
"Why were stations like Mir or Skylab put in orbits that decayed over time?"
] | [
false
] | [deleted] | [
"It takes more energy to get to a higher orbit. (And because of ",
"the tyranny of the rocket equation",
", what might seem like a small difference in energy requirements can translate into a substantial difference in fuel requirements.) That's a cost that has to be paid not just when you launch the station int... | [
"The ISS does need regular boosts.",
"Attach a rocket engine at its center of mass and boost, would be my guess as to \"how\"."
] | [
"The ISS does need regular boosts.",
"Attach a rocket engine at its center of mass and boost, would be my guess as to \"how\"."
] |
[
"Oumuamua was spinning end on end. It is possible the acceleration observed as it rounded the sun was due to some form of boomerang effect?"
] | [
false
] | null | [
"Space is very nearly a perfect vacuum, better than most artificial vacuums on Earth and often measured in atoms per cubic centimeter. The aerodynamics that make a boomerang work don't apply here. Light pressure is much stronger - and still incredibly weak.",
"It's not often that a paper makes my hair stand up bu... | [
"So the basic idea is that, after tracking the motion of 'Oumuamua, it was found that its acceleration didn't ",
" match what we'd expect from gravity alone. The Sun's gravity pulls stuff towards it, but it looks like there was also a weak force pushing 'Oumuamua away from the Sun too. The effect is small, but th... | [
"If it ever was a probe it would take 11,000 years for it to travel one lightyear at 26 km/s. This has been out there for some time. It's also tumbling which suggests the attitude control system is offline, and might have been offline since before humans invented fire. ",
"So derelict, garbage, or natural object.... |
[
"When an F-22 raptor lands on the runway, because of the stealth plating can ATC(Air Traffic Controll) see it on their radars?"
] | [
false
] | null | [
"The F-22, like most planes, will have a ",
" - a radio transmitter that broadcasts information about the plane. When taking off or landing at a friendly airport, an F-22 would have its transponder on, and thus ATC can track it no problem. The transponder will be turned off when stealth is required.",
"Should t... | [
"Should the transponder fail, the F-22 pilot will rely on radio contact with air traffic control. ",
"Stealth aircraft on non-combat missions usually carry a radar reflector. This 'breaks' their stealth so they can be tracked by radar."
] | [
"The F-22 is not a \"stealth\" aircraft, and is detectable by ground-based radar, although the radar return appears to be a smaller object. Additionally, when the craft begins approach, flaps and landing gear increase the radar cross-section."
] |
[
"Deep space probes that are in \"sleep\" mode while traveling. Do we just gamble and hope it doest hit anything like an asteroid?"
] | [
false
] | Just saw an article on the US space probe set to explore pluto that just "woke". So made me think if its on stand by mode, how do we know if it crashes? Or does it have a feature constantly active, like a laser, to detect objects and move it self? | [
"It is sent in a trajectory that doesn't intersect any known asteroids. This is not wicked, they are separated by hundreds of millions of km, so in most cases the simplest trajectory that works to intercept the planet is already safe enough.",
"Smaller objects that cannot be seen from Earth, i.e. micrometeoroids ... | [
"An asteroid hitting the Earth is a different matter - the Earth is a large gravity source and is actively pulling things towards itself. Asteroids in the area will, over time, tend to gravitate to us.",
"Asteroids hit the Earth all the time. Most of them are small and inconsequential, some are larger, like the R... | [
"Space is so mind boggling empty, that we ignore the chance of collision and just send probes on their paths without any security measures. The chance of collision is basically non existant for any prictical purpose and pictures of dense rock clouds are vastly exaggerated."
] |
[
"How, or why, do refraction and dispersion occur?"
] | [
false
] | I'm an A-level physics student and we've just covered refraction and dispersion. Our teachers have said we don't need to know why and how they happen but I'd like to know because it'll help me understand everything. They tried to explain but they've told me so many things that contrast that I don't know what's what any... | [
"Speed of light is constant in a vacuum, but not as it passes through matter. "
] | [
"See this animation and page for a good description. \n",
"http://physics.ucdavis.edu/Classes/Physics9B_Animations/ReflRefr.html",
"\n(Sorry I'm on mobile, you may have to copy/paste)",
"The frequency of light is constant, but it's speed is not. Light will slow down when it enters some medium such as glass or... | [
"To add, different frequencies of light (colors) are slowed differently in materials. Look up 'index of refraction vs frequency' plots on Google. \nThis means that light beams of different colors will bend differently if shot into some medium at an angle. This leads to the formation of rainbows (like the Dark Side ... |
[
"Is there a reason why 8 bits make up 1 byte?"
] | [
false
] | null | [
"A byte hasn't always consisted of 8 bits, it is hardware dependent, and so there have been implementations 4,5,6 and 7 bits in a byte. It was just how those implementers decided to represent that information. For example, ASCII is transmitted at 7 bits to the byte and hardware that made use of ASCII would have t... | [
"The 8th bit was used quite often as a parity bit, 7 bits gave 128 characters enough for the full latin alphabet plus common punctuation plus 1 bit for parity.",
"It was fairly common in the early days of computing, there is a funny story about Cray and Parity bits.",
"For a contrary view, Seymour Cray, premier... | [
"As powerful as it would be, I would still overcluck it"
] |
[
"Are there any plants/animals that have absolutely no elements in them heavier iron? ie life that doesn't require the explosion of a supernova to exist."
] | [
false
] | So I know that most stars only fuse up to iron so these are the most common elements in the universe, and that the human body needs some elements heavier than iron, like iodine, but is there anything on this lovely planet of ours that doesn't require elements heavier than iron to work? edit: thanks! | [
"Nope. There might've been at some early stage in evolution, but all single- or multi-cellular life that's around now requires (among other things), zinc, copper and molybdenum. ",
"Just to mention one example, there's copper in Cytochrome c Oxidase, and that one enzyme alone is present in all eukaryotic life and... | [
"I gotta point out a very common misconception in your title. It's true that supernovae might produce many of the heavy elements in the universe through the ",
"r process",
", but about half of the heavy elements are produced in the ",
"s process",
", which happens in some giant stars. There are also some... | [
"haha thanks, me too!",
"EDIT to ask a question, so the s process is just a bunch of neutron capture yeah? is it the case that this is not energetically favourable but just happens anyways cos there's loads of neutrons flying around with enough kinetic energy?"
] |
[
"How does an hydropower plant in a river affect the river?"
] | [
false
] | The water is running through Turbines, which should kill most fish. Is that not a big problem for wandering fishpopulations? | [
"Dams (whether they are hydroelectric or serve another purpose) fundamentally alter a lot of the underlying characteristics of a river and thus have very large impacts on a variety of life, mostly downstream of the dam, but also in the area immediately upstream that is inundated. In terms of the dam being a physica... | [
"Just to add to your as usual excellent write-up: the flood control coming with damming rivers often reduces the spring flooding of adjacent vegetation. While that is of course a desired effect from a civil engineering perspective, many fish species use those flood zones for reproduction and are badly affected by t... | [
"I will add that these impacts go beyond fish using flood zones to a whole variety of cascading effects. Example: spring floods create sandbars that are a specialized environment for both plant and animal species. Some tree species only sprout on the newly exposed post-flood bars. When the floods are eliminated the... |
[
"Is there a formula to calculate the average range of a photon (emitted as gamma radiation from a decaying radioisotope) with a particular energy in a particular material?"
] | [
false
] | I'd like to be able to calculate the average range of gamma emissions from radioactive nuclides in air, given the energy of the emission. I know the linear attenuation coefficient comes into it - and that the linear attenuation coefficient of a material depends on its Z and the energy of the photon, but I can't actuall... | [
"If one exists, it's probably some obscure empirical relation in old textbooks. In practice, you would usually just look up a value for the attenuation coefficient rather than trying to calculate it."
] | [
"The reason you aren't finding a formula is because it's fairly complicated and there are lots of different processes going on and they all have to be added up. There's ",
"the photoelectric effect",
" which depends on the energy level of every electron in every element in the material, ",
"Compton scatterin... | [
"Are you after a formula for the attenuation coefficient, or how to use the attenuation coefficient to work out what you need?"
] |
[
"How do we know the second law of thermodynamics is a law and not merely something we've never seen broken?"
] | [
false
] | null | [
"Keep in mind that the second law is an inherently statistical statement. There's always a non-zero probability that some process won't obey the second law. It's just that when you have macroscopic numbers of particles (on the order of Avogadro's number, say, 10",
" the probability that heat flows backwards is ef... | [
"Aren't all laws of nature like this? Couldn't the most fundamental laws be \"merely something we've never seen broken\"? ",
"Why should the sun rise tomorrow? We've seen a pattern in that it rises each day, but we can't be 100% certain that it would next day.",
"Truth is, there are no \"laws\". All science and... | [
"No, it's a law because of your second sentence, not your first."
] |
[
"If Humans Had Never Evolved: Top Animal Candidates for Sentience and Technology?"
] | [
false
] | Say the most 'advanced' of the Great Apes were the chimpanzees or bonobos or some kind of fairly stupid Lucyish creature, still kickin' it in Africa. Climate or circumstance made sure that hominids with big brains, a penchant for weaponry and an upright stance just didn't show up. Fast-forward however many millions of ... | [
"I don't think there's ever much benefit in speculating about future evolutionary directions, but the current non-primate leaders in tool use are probably ",
"birds of the crow family",
". Birds are also pretty good with language. "
] | [
"Peer review of comments came back negative, posts were redacted."
] | [
"Peer review of comments came back negative, posts were redacted."
] |
[
"I keep hearing that Voyager will take 10,000 years or 100,000 years to reach the closest star. Is it actually aimed towards a star or is it just going in a random direction?"
] | [
false
] | null | [
"Voyager 1 will pass within 1.6 light years from some nameless star in Camelopardalis. Voyager 2 will pass within 1.7 light years from 248 then in 300,000 years pass 4.3 light years from Sirius. So really, they're not aimed at anything.",
"Here is my source at JPL",
"."
] | [
"This doesn't directly answer your question, but I think it's still interesting: ",
"Voyager 1 travels at about ",
"17 km/s",
" or 61,200 km/h. ",
"Alpha Centauri is the closest star system to our solar system. That system is about ",
"4.37 light years",
", or about 41.5 trillion kilometers away. ",
"... | [
"Voyager 2 will pass within 1.7 light years from 248",
"For the record, the name of the star is ",
" 248. It's currently a little over 10 light-years away, but ",
"will be the closest star to our Sun 35,000 years in the future",
"."
] |
[
"Why do trash cans smell even after they've been washed?"
] | [
false
] | My plastic kitchen trash can smelled bad. Really bad. So I took out the trash, and washed it with soap and hot water. That didn't remove the odor. So I bleached it -- I sprayed it with a bleach solution, making sure to let it sit for 10 minutes before I rinsed it. Still have smell remaining. I washed it again. Still th... | [
"I can only speak in generalities -- but I think it's pretty reasonable that those smell molecules have simply diffused into the plastic. At the molecular level, the plastic will be quite porous."
] | [
"My first thought was actually a metal trash can. But I honestly don't know the answer to this question. I don't expect the polymers in mass produced trash cans to be as good quality as specialty ones that are found in a research setting."
] | [
"Are there certain plastics that are more or less susceptible to this? In other words, is there a trash can I can buy that won't have this kind of problem?"
] |
[
"Einstein said vegetarianism will improve health and increase chances of survival of life on Earth, how much more beneficial is a vegetarian diet?"
] | [
false
] | null | [
"Einstein was not a famous nutritionist. I can find no evidence that he ever made any scientific claims about the benefits vegetarianism."
] | [
"Given that Einstein was a physicist I don't think we should listen to his claims about nutrition, even if he actually said that (he didn't)."
] | [
"If you consider the fact that energy/mass is lost in every stage in a food chain due to the waste products that animal produce, or simply because energy is lost as heat as a result of the animal using it's muscle, then if everyone just ate plants we would have more than enough food for everyone.",
"tl;dr Adding ... |
[
"space time and earthtime"
] | [
false
] | I don't know if i'm saying this right but if time in space is different to time on earth, is the possibilty of being in space and having time move much quicker then on earth at all likely. By which i mean; say we were on earth and a star was going supernova in 1000 years earthtime (at the point of the star and not by w... | [
"There is no preferred universal inertial reference frame. However, there is a reference frame that has a unique property that the cosmic microwave background doesn't look hotter in one direction and colder in the opposite. We are moving about 600 km/s relative to this reference frame. This is too slow for relativi... | [
"This is not meant as an attack, but you are very confused about how relativity works. ",
"This article",
" is an excellent summary, and I would recommend reading it. If afterwards you have questions, come back here and ask. The problem is from where your apparent level of understanding is, it would take a lot ... | [
"The difference between time on earth and in space is incredibly small.",
"\"In 1976 the Smithsonian Astrophysical Observatory sent aloft a Scout rocket to a height of 10,000 km. At this height, a clock should run 4.5 parts in 10",
" faster than one on the Earth.\"",
"That's not far enough to be called \"oute... |
[
"Time Machine Question (More about how accurately we can calculate our place in time and space)"
] | [
false
] | [deleted] | [
"Well, ignoring the obvious problems with time travel, the position of the earth could be calculated fairly well for a couple million of years. You might want to check out works of Jacques Laskar, who simulated the behaviour of our solar system over 100 Million Years. He has also found indication for chaotic behavi... | [
"I hear this brought up a lot- and I'm not saying this about you OP, but as a trend- and a lot of people say it thinking it makes them super clever, but I believe asking this shows a lack of understanding of the laws of physics. ",
"All inertial reference frames are identical, and if you are travelling \"through ... | [
"The Earth is in free fall so it is in an inertial frame."
] |
[
"AI: How would it function without motivation?"
] | [
false
] | I keep hearing these opinions and predictions from the smartest people of the world like Musk and Hawking that AI will take over our planet in the future. I'm confused (well, duh!) We, as humans, are driven by motivation and emotions. Everything we do has a REASON for it. We don't go and kill someone - there's always s... | [
"This isn't a complete answer to your question, but consider the ",
"Paperclip Maximizer",
". It's a thought experiment that shows that an AI does not have to have \"evil\" intentions to be dangerous. Basically the idea is that someone makes an AI whose goal it is to make as many paperclips as possible. But wit... | [
"AI/Machine Learning PhD student checking in here.",
"The problem with your question, and similarly with the sensationalist articles surrounding the opinions of ",
"Hawking and Musk",
" is that at this point we don't know and can't really make this kind of prediction. Let me explain. I'll try and answer your ... | [
"The paperclip maximizer is a great example of the \"newsy\" uses of computers that raise questions like this. Why doesn't anybody ask \"Could a human with unchecked powers cause lots of problems?\" A computer with unchecked powers would be a dangerous thing, but it's not because of some deep flaw in our understa... |
[
"Can someone explain the implications of amino acid imbalances, and specifically how they link to l-tyrosine and phenylalanine?"
] | [
false
] | null | [
"L-tyrosine (Y) and phenylalanine (F) are usually discussed in regard to a condition called phenylketonuria (PKU). There are 20 different amino acids, all of which the body needs to make proteins. The body can make some of these on its own (these are called non-essential), but others you must get from the diet (e... | [
"Ah gotcha, that makes sense. Is there a connection between Y/F and none of the other essential amino acids (other than each other). Basically, my sister was claiming that ALL amino acids are dangerous because they cause other essentials to fall by the wayside during catabolism causing said imbalance. Is there any ... | [
"Amino acid \"imbalance\" really means amino acid deficiency. Amino acids are the building blocks of all proteins, so I don't understand what your sister means when she says they're \"dangerous\". As long as you have the amino acids you need, your body will be fine. Excess amino acids can't be stored, so you bod... |
[
"How does iron exist IN the earth without rusting?"
] | [
false
] | Better yet, how do we have it in our blood without it out oxidizing? There's water and oxygen in our blood. | [
"For the record: ",
"so yes, pure Fe2+ iron is not found in your blood or in the earth.",
"I think you mean that Fe",
" is not found in your blood or in the earth, because (one of) the ionic forms (Fe",
" and Fe",
" ",
" found in your blood and in the earth. Hemoglobin for example, as you mention in you... | [
"For the record: ",
"so yes, pure Fe2+ iron is not found in your blood or in the earth.",
"I think you mean that Fe",
" is not found in your blood or in the earth, because (one of) the ionic forms (Fe",
" and Fe",
" ",
" found in your blood and in the earth. Hemoglobin for example, as you mention in you... | [
"It's very hot in the Earth's core, hot enough to break down Iron oxides (Iron oxide decomposes at under 1600 Celsius, Earth's core is over 5000 deg. Celsius). Also, Iron Oxide is less dense than Iron, so the metallic Iron sinks to the core while rust would float higher up.",
"Also, Iron in our blood ",
" oxidi... |
[
"Why, with a sinus infection, does pressure in your sinuses/head build up whether you blow mucus put or suck it in?"
] | [
false
] | null | [
"The paranasal sinuses are poorly innervated - pain tends to be vague and poorly localizable in the sinuses because the brain has a difficult time precisely interpreting what little sensory input it receives from the sinuses.",
"When an acute bacterial sinusitis occurs, with all the inflammation and mucus product... | [
"But why would it seem to build pressure if you blow out or suck in? The same reason aggitating a sore limb would hurt?"
] | [
"The pressure you are feeling has extremely little to do with the mucus in your nose. The pressure is due to swelling and inflammation of the irritated mucosa in the nasal passages.",
"If you look at decongestants that treat sinus pressure and pain, they do not alter mucus secretions at all. All approved deconges... |
[
"Why do you sometimes randomly get that loud ringing noise in your ear for no apparent reason?"
] | [
false
] | [deleted] | [
"I responded to a similar ",
"thread",
" about about how tinnitus is thought to occur, and this thread was suggested. So for those interested: ",
"Tinnitus is defined psychologically as the spontaneous perception of sound in the absence of external stimuli, and neurophysiologically as aberrant activity within... | [
"Great answer on general tinnitus...but you missed that he was specifically asking about transitory tinnitus: The type that starts out of apparently nowhere quite loudly with a nearly pure tone, persists for several seconds and then fades away completely. Often associated (at least in my experience) with a temporar... | [
"Seeing how he says randomly, then I'd assume it's acute. I get it once or twice a month."
] |
[
"How do different immunosuppressants like Avonex and Imuran differ in their biological function?"
] | [
false
] | null | [
"Please, do not ask for medical advice here. Thanks."
] | [
"I'm not. I'm curious as to why 2 drugs, both labelled as immunosupressants, treat 2 separate illnesses. What is the biological mechanism behind immunosuppressants and how do their functions differ across drugs?"
] | [
"Ok thanks. I'll try again, and delete this one."
] |
[
"What is the fastest human sense?"
] | [
false
] | I've read a few blogs and articles that say that hearing is the fastest human sense. I've done searches in Google and Google Scholar with little success. However, I don't see many that cite very credible sources in Google and Google Scholar hasn't yielded anything pointed towards the question. I found this medical blog... | [
"Smell is actually a little part of your brain sticking its tendrils through the cribiform plate in your skull. You smell with a part of your brain, not a sense connected to your brain through a nerve or nerves. ",
"What? I thought that olfactory stimuli are transmitted through the olfactory nerve. And I don't kn... | [
"Smell is actually a little part of your brain sticking its tendrils through the cribiform plate in your skull. You smell with a part of your brain, not a sense connected to your brain through a nerve or nerves. ",
"What? I thought that olfactory stimuli are transmitted through the olfactory nerve. And I don't kn... | [
"Like three marijuanas? "
] |
[
"Difference Between Pain Medicines"
] | [
false
] | null | [
"First off, patient experience with various pain killers is highly variable for their specific painkiller aspect. ",
"While you may like ibuprofen for headaches and aspirin for muscle aches and naproxen for that trick shoulder, it may be very different for someone else. AFAIK, the reasons for this are not fully k... | [
"Great question! Let's keep this on topic without a lot of anecdotes kids! "
] | [
"Could you give me some grievous statistic or figure to convince me to never ever drink while on acetaminophen.... (I have a few times)?"
] |
[
"What does a wave function look like?"
] | [
false
] | [deleted] | [
"It is possible to see, using scanning microscopy, the interference pattern of delocalized electrons on a surface inside a ring of atoms, which you could interpret as a visualization of a wavefunction.",
"pic",
".",
"The \"height\" is related to the electron density."
] | [
"one of the postulates of QM is that the wavefunction itself is physically meaningless. Ψ(x,y,z,t) = ψ(x,y,z)e",
" is a general solution to the time dependent Schrodinger wave equation. Note the presence of i, why does the solution contain an imaginary number? well, you'll have to consult mother nature for that ... | [
"The problem is that the image you posted is actually not the 'wavefunction', but the mod-square probability density (psi-star times psi). There is no way to visualise the wavefunction itself - a good reason why is to look at the units of psi - inverse cubic meters square rooted. This has literally no real life ana... |
[
"If the flu kills approximately 36,000 people in the US every year, why aren't we doing more to prevent it like we are doing for ebola?"
] | [
false
] | The flu travels much quicker and more easily yet people seem to brush it off. | [
"There is a lot of research being done for influenza. The NIH is spending approx $312 million ",
"this year",
" in research. Then there are multiple other companies doing private, independent research. The problem with seasonal influenza is that it mutates every year. There needs to be a lot of research to ... | [
"From what I know, the deaths due to the flu are usually due to confounding factors, such as existing sever health issues.",
"And I think the death rates for each disease is quite significant. If you did not take serious steps against ebola you could potentially get a large population decimated."
] | [
"That's a common misconception.",
"Although elderly, sick, immunocompromised, young etc are more vulnerable to the flu. A significant number of healthy adults develop ARDS and die from the flu each year"
] |
[
"Why can i see the outline of the whole moon right now, even though only a sliver is lit up?"
] | [
false
] | null | [
"Reflected Earthlight: In the same way the dark surface of the Earth is lit by moonlight, the dark surface of the moon in turn is lit by the light reflected from the Earth."
] | [
"It even has a beautiful name: earthshine."
] | [
"Wikipedia link: ",
"earthshine"
] |
[
"[Mathematics] Probability Question - Do we treat coin flips as a set or individual flips?"
] | [
false
] | is having a debate on the gamblers fallacy, and I was hoping could help me understand better. Here's the scenario. A coin has been flipped 10 times and landed on heads every time. You have an opportunity to bet on the next flip. I say you bet on tails, the chances of 11 heads in a row is 4%. Others say you can disregar... | [
"I've always summarized it as such: ",
"People basically confuse two distinct scenarios.",
"In one scenario you are sitting at time 0 (there have been no flips) and someone asks you: \"What is the chance that I flip the coin heads eleven times in a row?\"",
"In the second scenario you are sitting at time 10 (... | [
"I've always summarized it as such: ",
"People basically confuse two distinct scenarios.",
"In one scenario you are sitting at time 0 (there have been no flips) and someone asks you: \"What is the chance that I flip the coin heads eleven times in a row?\"",
"In the second scenario you are sitting at time 10 (... | [
"You sir have answered a question that's bothered me since childhood and elegantly too. Props."
] |
[
"If the vacuum of space is such a great insulator why did the Apollo 13 astronauts nearly freeze?"
] | [
false
] | I didn't want to hijack the computer in space thread but the first answer made me think about this. Why is there any concern for heat loss in such a near perfect vacuum? | [
"Insulators function to inhibit the physical transfer of heat. (Conduction)",
"Heat is lost through space quite fast because the heat is radiating away faster than is coming in. (Radiation)"
] | [
"I'd be hesitant to say \"quite fast\" just because radiative cooling can be substantially slower than other forms. As noted, space does make a decent insulator, but certainly not a perfect one. For that matter, depending on the situation (for instance, how much sunlight you are receiving) the process could actuall... | [
"Imagine you're the designer of a spacecraft. Since there's no conduction or convection in a vacuum, you have only two tools for controlling temperature:",
"Radiative heat transfer physics tells us that warm objects emit energy in the from of photons (light). The rate of energy emission (power) is proportional ... |
[
"Probably another stupid Higgs question,"
] | [
false
] | null | [
"Where did my question go? ",
"edit: that wasn't the question, I just want to know"
] | [
"What was the question?"
] | [
"What was the question?"
] |
[
"When happens from the perspective of a photon when you shoot it towards the edge of the universe?"
] | [
false
] | So as I've learned from AskScience, when you shoot a beam of light towards an object, lets say a wall, it travels from the flashlight to the wall at the speed of light from the perspective of a stationary observer. But apparently, from the perspective of the photon, time is dilated so much that it gets there basically ... | [
"Really, it just makes no sense to talk about the perspective of a photon. They don't experience time, so they don't have a perspective."
] | [
"Neil deGrasse Tyson answered ",
"this",
" on his first AMA here on reddit."
] | [
"It would simply watch the universe age in reverse, and watch the universe fizzle out of existance as the light had not yet reached there."
] |
[
"Why can't scientist come up with a method to highlight the resistant proteins on cells?"
] | [
false
] | null | [
"Hi Chemrxt thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the followi... | [
"What does this mean? Resistant proteins? Highlight?"
] | [
"So when a human is giving a cancer drug, the cancer drugs helps the immune system technically destroy the cancerous cells; any cancerous cells that are left adapt (proteins in the outside of cells change, mutation, become resistant to that certain med). So why isn't there a method to hit cancerous cells with a fun... |
[
"Why is iron so abundant in the universe"
] | [
false
] | I understand Iron comes from the end result of fusion processes in very massive stars. However, looking at this article: raises a question: Iron is generated last in big stars. Why then is there so much more iron present in the universe than other elements which are generated before iron in the fusion cycle in large ... | [
"It's got to do with nuclear binding energy. The heaviest nucleus that can be created in a star is, if I remember correctly, nickel-56. So as a massive star ages, it accumulates a lot of nickel-56 nuclei in its core. When that star turns into a type Ia supernova, the nickel-56 nuclei are scattered into space.",
"... | [
"DISCLAIMER: Not a scientist, have no sources. Please someone with credentials confirm or deny the following. ",
"I read somewhere that Iron has the lowest \"energy potential\" (not correct phrasing). ",
"That is to say, when you fusion two hydrogen atoms together it takes a lot of energy but you get more energ... | [
"Yes, when you try to fuse Iron (or heavier) the reaction requires more energy than you get out.",
"http://hyperphysics.phy-astr.gsu.edu/hbase/astro/nucsyn.html#c1"
] |
[
"A quick question about S-Waves"
] | [
false
] | Last night I was watching BBC's Horizon, talking about the center of the earth. One scientist was saying how S-Waves can only travel through solid rock, hence were fundamental in proving the inner core of the earth is solid. What I don't understand is if S-Waves can only travel through solid rock, how do they pass thro... | [
"They don't pass through the liquid core. It's called the ",
"S-wave shadow zone",
". Only the P-waves go through the liquid outercore, but only with significant refraction. It's the P-waves that allow us to understand the solid inner-core. "
] | [
"True, but there is also mode conversion where the P wave that travels through the liquid outer core become s-waves at the inner outer core boundary, they then mode convert back to p waves at the next inner outer core boundary. The modelling work for the mode conversions led to the hunt for these weaker mode conver... | [
"The original S-waves that are propagated by a seismic event do not go through the core, and the P-waves are most certainly not totally converted into S-waves, probably only a portion. We can't measure the effect of the S-waves in the inner core, because they exist only in the inner core, which means that S-waves c... |
[
"If a sociopath loses his/her memory (amnesia, etc), is he/she still a sociopath?"
] | [
false
] | null | [
"You really need to clarify the question.",
"A sociopath is someone without empathy. According to the DSM-IV, a sociopath has 'antisocial personality disorder.' ",
"They are unable to relate to the feelings of others. This is associated with violence towards others, since they are unable to empathize.",
"I... | [
"So you cannot create a sociopath, i.e Dexter would be one no matter what his past was?"
] | [
"They would have no qualms about turning on you though, it would be hard to control an army of psychopaths"
] |
[
"Will the earth ever revert to Pangaea or a similar land congregation?"
] | [
false
] | null | [
"Earth has had several supercontinent cycles, taking somewhere between 250 to 500 million years to go from supercontinent to many continents to supercontinent again. Pangea was only the most recent, with Gondwana before that, Rodinia before that, Nuna (or Columbia) before that, Nena before that, and several before... | [
"To further this point, there are several hypothetical models predicting the future movement of the continents. Pangaea Ultima is one of the proposed names for a supercontinent that may form in about 250 MA, with the close of the Atlantic Ocean. "
] | [
"Wikipedia has a pretty good page on the ",
"Supercontinent Cycle",
"."
] |
[
"Is it possible to have damage in the brain so that you can remember something without ever seeing it?"
] | [
false
] | [deleted] | [
"It doesn't require brain damage to have or cause false memories."
] | [
"I think what OP is asking is if you can recall an event or object without visualizing it."
] | [
"Not what I meant. I meant that if event A happens, your eyes record it, and then send it to the part of the brain that records it, but don't send it to the part of the brain that lets you see it. So you wouldn't actually be able to see Event A happening, but you will be able to remember it."
] |
[
"Physics: Forward momentum with a headwind"
] | [
false
] | On the other thread I saw , and I have no idea how forward movement is achieved with a headwind. | [
"I am going to make the observation that the guy is standing (in the glider) at the top of a hill. The wind isn't just coming in horizontally, but it is actually coming ",
" as well because once it hits the hill it doesn't just stop, but kind of follows the hill. This will be relevant later.",
"Consider now a... | [
"A quick shitty drawing",
"The roughly wing-shaped object is the wing. The four arrows starting at the word 'wind' represent the wind. When they hit the bottom of the wing, the wing experiences a force in the direction of the long arrow pointing at a right angle from the base of the wing. It is perpendicular t... | [
"As it falls air hits its wings and the wings redirect the air backward.",
"This is the part I am confused on. How does it creat thrust?"
] |
[
"Is there any reason why Earth's orbit wouldn't be in the style of a Möbius strip?"
] | [
false
] | null | [
"The way gravity works all orbits have to be in the shape of a ",
"conic section",
". This means they can either be circles, ellipses, parabolas or hyperbolas."
] | [
"Not sure what you mean there. But yeah this is the only possible shapes for a single body orbiting around a more massive star or planet."
] | [
"So it already is in that style?"
] |
[
"Are we any closer to a functional and practical early diagnosis/screening for alzheimers disease? Are we any closer to reliable, safe treatments?"
] | [
false
] | Forgive me, . It has been years since I picked up the textbooks. Namenda is nice and all, but it's overpriced and isn't very effective unless Dementia is diagnosed early on. Oh and diagnosing AD is still only accurate after an autopsy. What are some of the recent advances?!? What exciting discoveries have been made? | [
"The aetiology of Alzheimer's is still large unknown and the subject of much discussion, conjecture, theorisation and experimentation. There are currently no known cures, and no treatments that substantially slow the progress of the disease once it becomes apparent."
] | [
"Thanks for the reply. ",
"I refuse to believe the fatalistic viewpoint, however. I'm willing to bet that advances have been made in early screening, and that there are promising drugs that haven't made it to human testing yet."
] | [
"There are drugs being tested",
" but the success rate so far has been zero, mainly because we still do not know the how, why and what of the disease. There are plenty of theories, and some of those have led to millions being spent on development and trials, but so far, no cigar."
] |
[
"Do our pupils dilate when we dream about light?"
] | [
false
] | Last night I dreamt about being in a very dark room for a long time. Eventually I walked outside and was met by this very bright daylight. It hurt my eyes, but the pain eventually disappeared, as it would in a real life situation, because of our pupils adjusting. I found this very fascinating, because it's probably all... | [
"Vivid dreams like the one you described typically occur during REM sleep. Interestingly enough, the pupils are generally constricted (the antonym you were looking for) during REM sleep, though they do dilate periodically during this time. This intermittent dilation occurs in conjunction with other physiological ch... | [
"I am going to preface this by saying that I'm probably not qualified to answer this question. That being said, something I learned in my high school psychology class seemed relevant, so I did some googling...",
"I didn't find a definitive answer, but I found enough information that I would fairly confidently ans... | [
"Tangentially related: There was ",
"an intriguing study",
" done 50 years ago experimentally testing the opposite direction of what you suggest, whether (real) pupil dilation and visual stimulus during sleep impacts reports of visual stimulus during dreams. They found no association, though add the usual cavea... |
[
"What exactly is happening when a body part 'falls asleep' and why does it hurt so much when it wakes up?"
] | [
false
] | null | [
"Almost correct (it's not a direct mechanical process for your normal dead leg) - the term for the short-circuit of nerves you're describing is ",
"paresthesia",
".",
"There are a number of causes (",
"see this excellent review",
"), but when you get a dead leg normally it's probably driven by ",
"ische... | [
"I study brains, not body nerves, so take what I say with salt.",
"Signals are transmitted along nerves by way of axons -- long tubes with gates in their sides (membrane). When the potential difference across the membrane goes past a certain threshold, the gates open and let ions into the cell. These ions spread ... | [
"from howstuffworks -",
"Nerve impulses carry sensation information from nerve endings in the body to the brain, as well as instructions from the brain to the parts of the body. When you interfere with this transfer by squeezing the nerve pathways, you don't have full feeling in that body part",
"I was just won... |
[
"What is the smallest 'thing' that can have a temperature?"
] | [
false
] | This is a question in the same spirit as: "What give's an electron its negative charge." Is there a fundamental thing that carries temperature (sort of like ye olde Caloric theory of heat transfer)? Is there any sort of quantum heat particle - like a phonon - for heat energy? If we follow the mechanical theory of heat,... | [
"The smallest \"thing\" that can have a temperature is a single particle that carries with it a kinetic energy. To see this imagine that we have a one particle system where the particle is at a high kinetic energy (equal to its average kinetic energy since there is only one particle in our system), and we place it ... | [
"Most of this is good, but you can define temperature to be one particle as for example using the kinetic theory where the average KE = 3/2(kT) for a single particle. For a system of N particles, the total KE is then 3/2(NkT). ",
"Where temperature becomes useful is in many particle systems, but you can use it to... | [
"Most of this is good, but you can define temperature to be one particle as for example using the kinetic theory where the average KE = 3/2(kT) for a single particle. For a system of N particles, the total KE is then 3/2(NkT). ",
"Where temperature becomes useful is in many particle systems, but you can use it to... |
[
"If an object keeps accelerating, will it eventually turn into a black hole?"
] | [
false
] | Since mass increases as speed increases, and mass goes to infinity as speed approaches c. | [
"No, also mass doesn't increase with speed.",
"It cannot become a black hole: there are coordinates in which it is stationary and thus obviously doesn't become a black hole. So it cannot become a black hole in any frame"
] | [
"but doesnt energy have an effect on the gravitational field according to general relativity?"
] | [
"but doesnt energy have an effect on the gravitational field according to general relativity?"
] |
[
"Why don't we sneeze in our sleep?"
] | [
false
] | null | [
"the trigeminal motoneuron pools that mediate the sneeze reflex are inhibited during NREM sleep and are actively suppressed during REM sleep as part of atonia. Which means it is much more difficult to sneeze during NREM sleep and nearly impossible in REM (without also causing waking).",
"http://www.reddit.com/r/a... | [
"Because there is more value in sleeping.",
"Sleep also inhibits other normal bodily functions, like hunger (shouldn't it be important to know when one is hungry?) and, more importantly, consciousness (what if there are predators nearby?)."
] | [
"But why is it beneficial when we are awake but not while sleeping? "
] |
[
"Why does it require more energy to accelerate a mass faster, as it approaches the speed of light?"
] | [
false
] | Does it have something to do with the higgs field? Assuming it exists? | [
"Well, the most intuitive, if you don't know much of the math, would be to say that the speed of light has to have the same value in every reference frame. You can take that as a principle, derive it from electromagnetism, or just do what Einstein did and note that experiment suggests pretty strongly that it's true... | [
"Nothing to do with the Higgs field - this was understood more than a half century before we even realized we needed a Higgs field.",
"The reason is that force isn't ",
" just the product of mass and acceleration as you might have learned in high school. Without getting into too much ",
"mathematical detail",... | [
"Pretty much yes. You have to accelerate the energy as well."
] |
[
"Is a covalent bond the strongest bond known?"
] | [
false
] | If so, why? If not, what is stronger? | [
"The answer is not so black and white, though. Yes, inorganic compounds can have lattice energies that are anywhere from ",
"600 to a few thousand kj/mol",
". The carbon monoxide bond energy and the N-N triple bond both have energies around 1000 kj/mol, making them stronger than some ionic compounds. Also, k... | [
"No. Ionic bonds are much stronger. It doesn't seem like it at first, since ionic compounds easily dissolve in water, but you have to think about bonds in terms of the energy needed to break them. ",
"The melting temperature of NaCl is 1474 F (801 C), this is an ionic bond.",
"Compare that to the covalent bonds... | [
"All true. The guy didn't seem like he needed this much info. Its like, \"How does division work?\"",
"\"Well, integrals...\""
] |
[
"I just did something amazing. Can someone help me settle my disagreement with my wife iver just how amazing it was?"
] | [
false
] | My wife and I were pulling M&Ms out of a two pound bag of M&Ms and trying to guess what color we had pulled out before looking at it. This quickly escalated to guessing pairs and then triplets. So, I would say, "blue, red, and red," and reach into the bag and pull out three. Neither of us got the triplet but my wife gu... | [
"You're not accounting for reordering. For a given string of six colors, there is a 1/46656 chance that you'll pull them ",
". But if you're just seeing if you match the colors that you say, you need to make each reordering of the same six to count as one. To do this, you need to compute 6!/6",
". This is 5/324... | [
"Why does that image use 26 M&M's to represent 25 M&Ms' worth of data?"
] | [
"Since he wants \"brown, brown, red, blue, green, and yellow\" in any order, the probability would be C(6,2)*4!/6",
" assuming equal distribution of the six colors. The binomial coefficient C(6,2)=(6*5)/(2*1) accounts for the two positions of the browns in the sequence; the 4! is there to count the different ways... |
[
"Would it be a good idea to diversify a newborn child's microbiome as much as possible?"
] | [
false
] | When a new child is born, im to understand that both parents should hold the child with their bare chest or at least get good skin to skin contact as to populate their microbiome with the parents bacteria and such. Would it be a wise idea to have another two or three people who exhibit good health get in there just for... | [
"The skin microbiome is actually not what you are going for here. It’s important but you don’t really want the skin flora to be the source of gut diversity (I think the microbiome you are interested in). The main seed of the gut comes from the mother during passage through the birth canal - largely the GI flora of ... | [
"Thank you! ",
"Im actually interested in all biomes. Thats really interesting on the establishing of the gut biome. And im glad im aware of the diet role. It seems to make sense thinking about it, but im glad you brought it to words. ",
"I was in fact though asking about the skin biome in particular, haha.... | [
"Gotcha. There isn’t much work in the skin area right now (I have a grant at the moment to study it though!). I think the skin to skin is more for attachment though it wouldn’t surprise me if that is mediated by some microbiome sharing we don’t understand yet. The goal would be to not get the skin flora in the gut ... |
[
"Is the speed limit of light only determined experimentally?"
] | [
false
] | Or is there some theoretical calculation/simulation/model that tells us precisely what that value is and that doesn't rely on any experimentally determined values at all, during the course of that derivation? I think the answer is No. Still, what would the implications be if we could formulate a theory based only on ax... | [
"To generalize your question: \"Can the numerical values of physical constants be predicted theoretically?\"",
"This is actually a more important question than at first glance. First if all, the absolute numerical value of a constant depends entirely on your choice of units, so it is not very fundamental. Instead... | [
"Even if there was, the computation or simulation would be based on the properties of the universe. It would basically just be a really, really inefficient way of measuring it.",
"Something along the lines of what you're talking about comes from atomic physics. The fact that integer-spin particles can occupy the ... | [
"Although there is not complete proof that all such numbers can be predicted theoretically at this point, that is really the end goal of science: to be able to predict everything.",
"If we are to take the idea of no free variables seriously, we'd need a theory saying that the universe is the way it is because tha... |
[
"Can a virus infect a bacterium?"
] | [
false
] | null | [
"Yes viruses that infect bacteria are known as bacteriophages or simply as phages. ",
"Generally phages are can be categorised in to two groups; lysogenic and lytic, this refers to the the life cycle of the phage. Lytic phages insert their DNA into the cell which stays separate from the bacterial DNA and in most ... | [
"That was an amazing answer. Thank you for taking the time and giving the effort. "
] | [
"Lol thanks, did some research involving phages a few years ago and found it pretty interesting."
] |
[
"What is the physical meaning of the velocity of electronic information transmission?"
] | [
false
] | I am studying electric circuits and the book explains that there is a difference between electronic transmission of information and transport of electrons through conducting wires, pointing out that the former occurs at a rate 12 orders of magnitude higher than that of the latter. While I understand what is physically ... | [
"Think about it this way, when you put water through a hose, it takes a while for the water to come out the other end, right? The speed of water in the hose is analogous to the velocity of electrons in a wire.",
"Now think about the hose again: this time, the hose is already full of water. When you turn the wa... | [
"In a circuit electrons are just carrying the charge, but there is also an ",
" around them. When you move a charged particle, it changes a field around it and those changes propagate in the field with a speed that can be different from the speed of the particle that caused those. A very rough analogy - you hear ... | [
"This is transport of electrons through conducting wires",
"As you can see, this is VERY slow, but like shadydentist said, electronic transmission of information is different in that it works by essentially one electron pushing into another and so on, like a set of dominoes."
] |
[
"Does gravity cause heavier isotopes in gasses/liquids to tend towards the bottom of their container?"
] | [
false
] | [deleted] | [
"Yes.",
"But it's a pretty subtle effect, and in natural systems is going to be masked by much more dominant fractionation and mixing effects. "
] | [
"I'm not sure if just gravity would be enough, but centrifuges are used to separate isotopes."
] | [
"What this man said, however I imagine Brownian Motion would overpower it in our regular gravitational field."
] |
[
"If you are past the sound barrier in a plane do you still hear the sounds you create?"
] | [
false
] | [deleted] | [
"Sound is a transversal wave that needs a carrier medium. In most cases, this carrier medium is air. The maximum speed of sound waves in air is somewhere around 343 metres per second which equals 1235 km/h. \nIf you are faster than this, the sound waves you produce aren't faster than you anymore, which means you ca... | [
"If you are in a closed cabin, the air around you is moving with you and sound will propagate normally through that air.",
"If you were describing a scenario where you were moving in a stream of air faster than the speed of sound, then no, sound cannot travel \"upstream\" through the air fast enough to reach your... | [
"Yes, you would, because the metal that the plane is made of is not moving with respect to you or the engine making the noise (and neither is the air inside the cabin)."
] |
[
"If 98F is my inner temperature, why does it feel so hot when the ambient temperature is 97F?"
] | [
false
] | Why does my body feels the need to cool itself at that temperature? | [
"Because your body is constantly generating more and more heat you'll only feel comfortable when your body is able to shed heat at the right rate. ",
"At 97F the air around you is barely conducting any heat from your body, but down at 70F it feels just right.",
"But then water at 70F will feel pretty chilly, be... | [
"A good point to be made about perceived temperature is that we do not sense temperature, we sense the rate at which heat is conducted and whether it is conducted away from or towards the body. ",
"This is the reason your bathroom floor feels colder than the bathmat next to the tub does. The tile or vinyl conduct... | [
"Yes, two objects in the same environment are typically the same temperature the only reason one feels cold or warm is its conductivity of heat. "
] |
[
"Do the particles within an atom gravitationally attract each other?"
] | [
false
] | null | [
"Yes, but gravity is much weaker than all other forces on that scale."
] | [
"How do we know? Has it been confirmed experimentally?"
] | [
"Well it’s essy to calculate using Newton’s law of gravity and Coulomb’s law if electrostatics."
] |
[
"Where would you have to be standing on Earth such that you were furthest away from the Earths centre?"
] | [
false
] | [deleted] | [
"The summit of ",
"Chimborazo",
", Ecuador."
] | [
"its location along the ",
"equatorial bulge",
" makes its summit the farthest point on the Earth's surface from the ",
"Earth's center",
"."
] | [
"The Equator bulges an average of 43km (27mi) farther than the poles. Everest being much farther from the equator means it isn't the highest point from the core, just the highest above the surface."
] |
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