title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How similar is reading notated sheet music to reading the written word?"
] | [
false
] | I help teach children music literacy (specifically on-staff notation for piano students). I often read articles about different ways to enhance this process for them, and I also occasionally read articles about teaching literacy in general to children. Some are very practical tips from fellow teachers, some are academic research. What I would like to know is, is it possible to take research on teaching general literacy to children and apply those findings to teaching music literacy? Are the brain processes for reading a book aloud similar to reading a piece of sheet music and performing it? Apologies if the flair isn’t quite right. I’m not actually sure what kind of question this is! | [
"I found this interesting article on musical dyslexia that I think answers your question from a neurological perspective.",
"https://neurosciencenews.com/musical-dyslexia-17971/amp/",
" ",
"They are different. Apparently reading music activates a few of the same parts of the brain as reading written words but... | [
"Non-scientist here, so take this with a very large grain of salt",
"Reading symbols and converting them to a meaning is probably both present in sheet music and regular reading. The problem is however, that people are taught reading from a very young age and are assigned to read a lot. This isn’t the case with s... | [
"I would somewhat disagree, there are two routes to reading: ",
"the phonological route - converting symbols to sounds to access meaning (grapheme-> phoneme -> word identification -> meaning).",
"the lexical route - memory of practiced patterns of symbols that mean that memory can be accessed without this conve... |
[
"Why does your heart rate decrease when you hold your breath? Wouldn't that make your heart work harder?"
] | [
false
] | I cannot seem to comprehend this phenomena. | [
"I'm not sure why this is but on a related note, if you keep your mouth closed and try breathing out then your heart rate will increase due to increased pressure in the chest (",
"http://en.wikipedia.org/wiki/Valsalva_maneuver",
")."
] | [
"Your heart is a strong muscle in the body that uses up oxygen as it pumps. If it can slow down, this will conserve oxygen.",
"This response is thought to be a vestige of the ",
"mammalian diving response",
". It often requires facial submersion, but in young adults just a breath hold has been shown to sign... | [
"The same amount of oxygen will get circulated no matter how fast the heart is pumping. There will be a difference in how quick it goes around (not a big deal if standing at rest) and how much energy it takes to get it around."
] |
[
"How do astronomical observatories make self-positioning?"
] | [
false
] | If they have static "earth" coordinates, do they consider tectonic plates movement? If they constantly calculate their coordinates what points they use for the references? What the coordinate system do they use and where is origin of this system? | [
"Hello, amateur astronomer here. I agree with my learned geologist friend that the baseline is where we know where to expect celestial bodies. This can quite easily be calculated using historic movements whilst factoring in other variables such as gravity of nearby bodies. ",
"On a far grander scale they use very... | [
"Just to add to this, one component that ",
" taken into account during certain high-precision observations is the ",
"Earth tide",
". Much like tides on the ocean, the solid ground beneath your feet can rise and fall as much as a meter twice a day, depending on your location and Moon phase.",
"This turns o... | [
"Hello geologist here. To answer part of your question the movement of plate techtonics is not take into account. This is because observatories use lattitude longitude elevation date time and orientation as their refecernce points for where they are and they sky should be at any given time, much like starmap apps o... |
[
"How Can Drugs Affect You for 12 Hours?"
] | [
false
] | I take Dextroamp ER which has effects that last for for 12 hours. How does this happen? Wouldn't my body digest it before then? Also, how does the effect stay consistent for such a long time? | [
"Drug metabolism",
", includes two basic premises. ",
"Pharmacokinetics",
" and ",
"pharmacodynamics",
" which describe how drugs react within the body. A drug that is absorbed into the blood stream quickly may have a very long half life within the body because the enzymes and processes that break it dow... | [
"The big one here is pharmacokinetics. There are several ways to extend the life of a drug in the body but any drug that follows first-order kinetics will need to have a restricted clearance rate to extend its activity"
] | [
"A nice easy concept to get your head around is the \"therapeutic window\". There's a minimum concentration level (i.e. level of the drug in your blood) that the drug must reach in order to have an effect on your body, below this, nothing will happen. There's also a higher dose level above which, you'll start to ex... |
[
"In the Scientific American of 1863, it's claimed that if the sun were made of coal, it would only last 5,000 years. Given our present knowledge, how accurate was their estimate?"
] | [
false
] | In this month's Scientific American, in the "50, 100 & 150 Years Ago" section, there is this excerpt from August 1863: The Sun "If the sun were composed of coal, it would last at the present rate only 5,000 years. The sun, in all probability, is not a burning but an incandescent body. Its light is rather that of a glowing molten metal than that of a burning furnace. But it is impossible that the sun should constantly be giving out heat, without either losing heat or being supplied with new fuel. Assuming that the heat of the sun has been kept up by meteoric bodies falling into it, and proof has been given of such fall, it is possible from the mass of the solar system to determine approximately the period during which the sun has shone as a luminary. The limits lie between 100 millions and 400 millions of years." The speculation on the sun's source of fuel was interesting enough, but I also thought their 5,000 year coal estimate was interesting. Presumably they had a decent idea of the sun's mass, but how accurate was their estimate of the sun's energy output? Given today's knowledge, how fast would the sun exhaust its fuel if it was made of burning coal? Of course, that's setting aside the physics of whether a sun-sized lump of coal like that would be stable. | [
"Coal's energy density is ",
"24 megajoules per kilogram",
" according to Wiki. I'm going to neglect the mass of the oxygen required to combust the coal. ",
"(1 solar mass) x (24 MJ/kg) / (1 solar luminosity) = 4000 years",
"So their estimates of coal's energy density (which will vary depending on the type ... | [
"Fascinating! This WP section has some interesting historical tidbits about the discovery of the sun's actual power source.",
"http://en.wikipedia.org/wiki/Hans_Bethe#United_States"
] | [
"Wow! I had no idea that it wasn't until 1938 that we figured out the exact process by which the sun shines. For some reason, I figured it would have fallen out of one of Einstein's or some other early nuclear physicist's papers on atomic physics. It's such a fundamental question."
] |
[
"If a wooden structure (let's say a log cabin) is adequately protected from moisture and things like termites and fungus, could it last indefinitely? (Let's say 100,000 years.)"
] | [
false
] | null | [
"True, but I think that was the gist of the question, i.e. under what circumstances can wood be preserved, and for how long?",
"Here",
" is a fairly-recent story about a mummified forest found in the Arctic that's between 2 and 10 ",
" years old. Note that it's a ",
", not ",
" forest - this is still the ... | [
"Streaming Link"
] | [
"You can ",
"buy",
" wood that is 50,000 years old, so I am going to go with yes on that."
] |
[
"Do people’s core personalities change as they get older, or do they just mature and adapt?"
] | [
false
] | null | [
"This may not be the right sub for this question as the anecdotal/speculative answers so far illustrate. So in recognition of the theme of the sub, but without the knowledge to comment on the quality of the sources, here are some studies and articles about studies that I got on a quick google of the topic:",
"APA... | [
"I don't think you're arguing to the contrary, so I just want to add to your comment by saying that this is absolutely the right sub for this question. Psychology is a science, and personality psychology is a core branch of psychology. However, it's difficult to study personality experimentally, so researchers who ... | [
"Lot of speculation here. Psych generally uses the Big 5 (OCEAN) to quantify \"personality\" - certainly far from perfect but the most scientific way to quantify personality traits at the moment. Studies indicate ~50% of each of these traits is genetic in origin, so we can safely say that about half of a person's p... |
[
"Am i right for a Masters Degree in CS? What will it take?"
] | [
false
] | I just finished college (Information Technology degree) and I'm in the process of evaluating my options. I really enjoy my field and I couldn't picture myself doing anything else but so far, I've had terrible experiences working in the private sector and I've always wanted to devote myself to research and apply my knowledge to an interdisciplinary area. I may have the opportunity to get a scholarship to study a Masters Degree in Computer Science but I don't know if I've got what it takes for it. Any advice from my fellow redditors? | [
"MS in CS degree holder here. What would be your end goal after getting another degree? If you want to do research, a masters degree will open up some opportunities but not nearly as many as a Phd. Also, keep in mind CS research is essentially applied mathematics research.",
"IT has absolutely nothing to do with ... | [
"Vector Calculus, but it's been quite a while since i took it. What kind of math courses do you recommend to refresh my math skills?"
] | [
"Integral and differential Calculus and discrete mathematics are essential. ",
"What area in CS are you looking to concentrate in? What sort of course offerings does the University that you are considering have?"
] |
[
"What is loop quantum gravity and how does it differ from String Theory?"
] | [
false
] | I'm only in my sophomore year in high school, and they don't teach particle physics here at my school. I've read some books on String Theory, but recently I came across "loop quantum gravity" and I don't really understand what it is. | [
"This is difficult because, according to general relativity, gravity is not a force. Instead, it's a property inherent to space itself.",
"I dont know why these kind of statements are so popular.. You can describe gravity with a spin-2 force field. It is just that at a classical level the geometric description is... | [
"This is difficult because, according to general relativity, gravity is not a force. Instead, it's a property inherent to space itself.",
"I dont know why these kind of statements are so popular.. You can describe gravity with a spin-2 force field. It is just that at a classical level the geometric description is... | [
"A couple articles might be helpful.",
"(1) First, about Loop Quantum Gravity (LQG), here is an excerpt from ",
"this article",
": \"LQG has as one of its central features that space itself is discrete. Imagine a common analogy for gravity: a bedsheet pulled taut, with a bowling ball in the center. Rather tha... |
[
"Would we be able to travel places if we just levitated, using any means not directly in contact with the Earth(some kind of thrust generating machine) and allowing the Earth to rotate as usual?"
] | [
false
] | null | [
"No. If you throw a ball up in the air, it doesn't fly behind you"
] | [
"Throwing up a ball and staying above the ground without coming back are two different scenarios. In my query I mentioned levitation. The ball will fly back if we throw it up while standing on a moving object e.g a train. "
] | [
"This is not true. If you are inside of a closed moving train, the ball will land back in your hand. There is no magical physics that only applies to levitating objects. If you like, you can think about a balloon or a helicopter. Neither of those magically zooms backwards the moment it is no longer in contact with ... |
[
"Do I really need special eyewear for viewing an eclipse? Why/why not?"
] | [
false
] | The optics part of my physics series was a bit rushed, but I reckon with some thought I could understand why it's damaging (or why it's not) | [
"Yes! I posted this link in another thread:",
"NASA - Eye Safety During Solar Eclipses",
"They have this part in bold: ",
" The first paragraph discuses why. ",
"\"Even when 99% of the Sun's surface is obscured during the partial phases of a total eclipse, the remaining photospheric crescent is intensely... | [
"In spite of these precautions, the total phase of an eclipse can and should be viewed without any filters whatsoever. The naked eye view of totality is completely safe and is overwhelmingly awe-inspiring!>",
"Is the last line of the article..."
] | [
"It's like looking directly at the Sun... because you're looking directly at the Sun. Having part of it blocked off doesn't help much, in fact it's worse because it makes you think you can look at it for a long time. But the intensity of the light is still the same even if there's less of it, so it can still damage... |
[
"What are the processes in warm blooded creatures that regulate body temperature so precisely?"
] | [
false
] | null | [
"That just tells me it's generated in deep organs and lost to the environment, I was looking for a bit more depth than that. Besides it doesnt address how the body so finely tunes it's temperature. "
] | [
"That just tells me it's generated in deep organs and lost to the environment, I was looking for a bit more depth than that. Besides it doesnt address how the body so finely tunes it's temperature. "
] | [
"The hypothalamus gland, located at the base of the brain, controls internal body temperature. This gland responds to sensory signals from temperature receptors in the skin and deep inside the body. The hypothalamus establishes a \"set point\" for the internal body temperature, then constantly compares this with it... |
[
"Do multiple wounds take longer to heal than a single one?"
] | [
false
] | null | [
"Assuming several things:\n1. all the wounds are exactly the same in type, size and depth\n2. there's no underlying infection\n3. blood supply hasn't been compromised (either due to the wound or due to the person's hand's arterial supply)\n4. the general condition of the hands are the same, eg no skin disease on on... | [
"So if I have this correct, each wound will take a different amount of time to heal but due to each wound being unique and it is not impacted by the quantity of wounds?",
"Edit: Because wow, what happened to my spelling."
] | [
"Thanks for the detailed answer! Really interesting "
] |
[
"Is the net biomass of Earth constant?"
] | [
false
] | Is there any real way of scientists estimating the total mass of all the organisms on Earth? And if so, is this total biomass constant, increasing, decreasing? If increasing/decreasing, where is the extra mass coming from/going to respectively? | [
"Pretty much, since most biological material is built on a carbon backbone."
] | [
"It changes depending on how much carbon is sequestered in non-biological traps, like carbonate rocks or fossil fuels. Carbon trapped in these is not a continuously cycling part of the carbon cycle. "
] | [
"Right, so it depends on how much of the Earth's carbon supply is actually participating in the carbon cycle?"
] |
[
"Would burning alive be excruciating or would shock/adrenaline block most of it?"
] | [
false
] | I've had a pretty natural fear of burning alive (dreams about it and such) and seeing stuff like the woman killed in the elevator this week is deeply disturbing. Having had small burns before I know how painful even second degree burns can be. My question is would it hurt that badly all over your body the whole time or would the pain mostly be blocked? Obviously it wouldn't be pleasant but surely it can't be as bad as I'd think, right? | [
"My intensive care unit treats burns, so we see the pretty bad ones; usually anything from 30% upwards. People with big burns are often not screaming with pain, for several reasons I think; full thickness burns are not painful as the nerve fibres have been destroyed but its very unusual for someone to have just ful... | [
"Depends on how you burn. ",
"Medieval and Renaissance executioners would, depending on the accused's crime, their mood, how much the relatives bribed them, the time of day, and any number of other highly scientific factors, either prolong their victims' suffering by causing them to burn slowly from the bottom u... | [
"Check out an ",
"escharotomy",
" (NSFL) used to treat burn patients. Pretty brutal."
] |
[
"What did the ice front look like during the ice age?"
] | [
false
] | Would it appear as a wall of ice or more of a gradual slope that you could walk on. Are there any modern day places that might look similar? | [
"It would have looked like the end of modern-day glaciers. In fact, they were glaciers at the ends. In fact, we are still in the ice age today, as there are still significant parts of the earth covered by ice."
] | [
"TIL glaciers aren't just floating ice mountains. This changes everything. Thank you."
] | [
"The general public often refers to the last ",
"glacial period",
" as the last ice age, but scientists call the last 2.5 million years ",
"the quarternary ice age",
" during which there were many ",
"glacial-interglacial periods",
". Interestingly the last interglacials periods tended to last only abou... |
[
"Do butterflies remember being caterpillars?"
] | [
false
] | null | [
"Yes and no. Butterflies don’t have a complex memories that humans have, so no they don’t remember being caterpillars. However, caterpillars can be trained to respond to stimuli and they will remember how to react to that stimuli when they’re butterflies. So no they can’t remember being caterpillars, but they can r... | [
"While some parts of a pupating insect do completely dissolve to form new parts, many of the critical organ systems, including the trachea, digestive system, and parts of the nervous system, remain intact, though they undergo some changes. Here's ",
"a link",
" to the paper that found this persistent learning i... | [
"I remember reading in an article years ago that when a caterpillar transforms, it dissolves into a liquid in the chrysalis. Do the nerves/brain of the caterpillar stay intact somehow in that process? Or do we not know how the training memories are stored?"
] |
[
"Did Marie Curie ever wonder if the radiation she was studying was dangerous?"
] | [
false
] | null | [
"Both Curies were plagued by ailments—burns and fatigue—that, in retrospect, were clearly caused by repeated exposures to high doses of radiation. Both, too, were resistant to the suggestion that their research materials caused their ailments.",
"https://www.smithsonianmag.com/history/madame-curies-passion-741835... | [
"Thanks for this link! After 4 years of performing crystallizations she only had a thimble-ful of radium?? Wow she was dedicated! The world owes her so much for her sacrifice"
] | [
"If you look at some of the devices created years after her discoveries, radium paint (radium girls who painted clocks) and Shoe-fitting fluoroscopes people had no clue.",
"They would have probably attributed the symptoms to long nights in the lab and clumsiness, poor eating habits, or any number of bad habits, n... |
[
"Any evidence for fertile hybrid origin for *Homo sapiens* ?"
] | [
false
] | There is increasing evidence being reported in the scientific literature of fertile hybrids forming new species for both plants and animals. Orchids of the genera and , rodents , Frogs , Guenon monkeys to name a few examples. A common theme reported is that fertile hybrid formation seems to be associated with ecotones, zones of overlap in species that once had ranges completely separated. Fertile hybrids can result where there is a wide difference in number of chromosomes between parent species. This leads up to my OP question, is there any evidence to suggest that modern humans, , has origin as a fertile hybrid species of two proto-human Hominid species that once had allopatric distribution that over time came to overlap, I assume in Afirica ? EDIT TO OP: Looking at a few Hominid timelines, and assuming can be traced back in time ~200,000 - 220,000 years as suggested from genetic studies, there are a few possible paths for a fertile hybrid origin: 1) 2) 3) 4) 5) others ? | [
"There is definite evidence that we cross bred with Neanderthals, it’s quite clear in our DNA. I don’t believe there’s evidence that we are the product of two separate species producing a third, it’s mostly just our ancestor species gaining genetic information from others as we progressed."
] | [
"All humans are most definitely the same species, starting with the standard biology 101 definition ”can interbreed, producing fertile offspring”. We’re also the same subspecies, ",
". \nThere’s some Neanderthal in those of us that are of European descent, but not enough to make them (or any other human subgroup... | [
"All humans are most definitely the same species, starting with the standard biology 101 definition ”can interbreed, producing fertile offspring”. We’re also the same subspecies, ",
". \nThere’s some Neanderthal in those of us that are of European descent, but not enough to make them (or any other human subgroup... |
[
"If something was on fire in a fridge that could go to extremely low temperatures and it kept getting colder. Is there a lower temperature limit where the fire can no longer exist?"
] | [
false
] | null | [
"Do note, however, that different reactants can ignite at different temperatures. ",
"Foof",
" for example:",
"\"Being a high energy oxidizer, dioxygen difluoride reacted vigorously with organic compounds, even at temperatures close to its melting point. It reacted instantaneously with solid ethyl alcohol, pr... | [
"Do note, however, that different reactants can ignite at different temperatures. ",
"Foof",
" for example:",
"\"Being a high energy oxidizer, dioxygen difluoride reacted vigorously with organic compounds, even at temperatures close to its melting point. It reacted instantaneously with solid ethyl alcohol, pr... | [
"There is a technical term for the temperature that you describe. It is called a ",
"Flash Point",
".",
"The flash point is the lowest temperature at which a substance will burn sustainably.",
"Below the flash point the vapour pressure of the combustible material is too low to supply enough fuel for a susta... |
[
"\"There is no cure for smallpox, but vaccination can be used very effectively to prevent infection from developing if given during a period of up to four days after a person has been exposed to the virus.\" How does a vaccine work AFTER being exposes? How can giving you more of the virus prevent it?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason:",
"We do not debunk or vet theories or offer peer review on ",
"/r/AskScience",
".",
"For more information regarding this and similar issues, please see our ",
"guidelines",
".",
"If you disagree ... | [
"Huh? How is this peer review or theory vetting? The scientific consensus is that you can apply the vaccine four days after infection, I'm simply asking how that works?"
] | [
"It is absolutely not the scientific consensus that vaccines work after infection, with very rare exceptions (rabies - see a recent question asking how that works). If you have a genuine source making this claim, please link to it. Otherwise this is asking to review someone’s incorrect pet theory."
] |
[
"Why are nuclear fusion explosions not 100% symmetrical?"
] | [
false
] | Please see photos in comments as an illustration of my question | [
"Explosions aren't completely symmetrical for the same reason that no cut cube of steel is perfectly cube-shaped. The mechanical limitations of how we make stuff will always result in imperfections. There's also the \"imperfections\" in how the nuclear reaction won't advance through the reacting material with 100% ... | [
"Great response. Thank you "
] | [
"https://commons.m.wikimedia.org/wiki/Category:Photos_taken_with_Rapatronic_cameras"
] |
[
"It is estimated that there are between 1-10 quadrillion ants on Earth. How did we come to that number?"
] | [
false
] | null | [
"Count/ estimate the number of ants in individual colonies of particular species. ",
"Count/ estimate density of colonies of each species in different environments and ecosystems. ",
"Multiply everything out by the measured area of those different environments and ecosystems on the planet. "
] | [
"Exactly this, and hopefully when all was said and done, the number on the calculator screen was in the 3 quadrillion range (allowing an error of a factor of 3 up or down within 1-10 quadrillion)."
] | [
"Start with ",
"https://en.m.wikipedia.org/wiki/Fermi_problem"
] |
[
"If the electromagnetic force overcoming the \"strong force\" is responsible for decay -- why do unstable isotopes with a small nucleus decay?"
] | [
false
] | Sorry for the dumb question, I am just trying to better my understanding of physics but I am not very well educated. Specifically, I understand that say, when uranium 235 is hit with a free neutron, the Uranium 236 isotope fissions, because its nucleus is bigger than the distance that the strong force is capable of exerting, (about the diameter 2.5 protons?), so the electromagnetic force therefore has enough energy to pull the deformed nuclei apart -- but what is causing unstable isotopes, say carbon 14, to decay, when their nucleus is so small? Writing this out, I'm thinking that my understanding of the "strong force" is totally wrong... surely it doesn't have the kind of centre of "force" that idea of competing forces seems to imagine... I really don't understand where the strong force between the nucleons in the nuclei exist... is it between the individual particles themselves? So I guess I'm trying to find out the relationship between the stability of isotopes to the proton/neutron ration, and how this relates to the strong force/electromagnetic force equilibrium that I was under the impression sort of holds an atom together? | [
"Not all decays of unstable nuclei are due to the electromagnetic force overcoming the nuclear force. Your example of Carbon 14 decays via beta emission, and the weak force is responsible for beta emission. Other nuclei decay by emitting alpha particles (He nuclei), which involves the alpha quantum tunnelling throu... | [
"Oh boy, there's a bunch of things to point out so let me just do one of them. Carbon 14 decays via ",
" which is due to the ",
" which is the force which controls quarks changing flavours. When carbon 14 decays one of its neutrons is converted into a proton due to one of the 'down' quarks changing flavour to... | [
"Not all decays of unstable nuclei are due to the electromagnetic force overcoming the nuclear force. ",
"oh wow... it seems so obvious to me now haha... Thanks for this, it's what I needed. I still struggle in understanding how adding a neutron is able to destabilise the nucleus, is it to do with the energy of a... |
[
"Are there clear examples of self-destructive behavior, similar to alcoholism or overeating, in other species?"
] | [
false
] | This question arose out of a discussion of alcoholism. Essentially, do other organisms eat, drink or otherwise over-indulge themselves to death? | [
"Laboratory rats were given unlimited access to intravenous cocaine hydrochloride or heroin hydrochloride. Animals self-administering cocaine quickly developed a pattern of episodic drug intake, with periods of excessive cocaine self-administration alternating with brief periods of abstinence. Subjects allowed cont... | [
"But what about the ",
"Rat Park",
" experiment? Were the laboratory rats only interested in drugs because their living conditions were bad?"
] | [
"Alcoholic Monkeys."
] |
[
"Can a compressed helium gas balloon be used to slow an object down from free fall"
] | [
false
] | I'm wondering if a space probe, for example, which is descending from orbit (from either earth or Mars) can be slowed by deploying a helium balloon from compressed gas. Would the balloons upward force be enough to slow the fall? Is this a viable alternative to parachutes? | [
"Answer! ",
"http://what-if.xkcd.com/62/"
] | [
"Theoretical, yes. I'll leave out explanations listed elsewhere, but perhaps unmentioned is that the helium won't generate any lift until in the lower atmosphere (when it can displace a heavier gas), and by then your velocity would be too high for any substance we know to realistically contain helium and be lightw... | [
"Not sure if I get the question right ... but I will try to answer:",
"You only have free fall in vacuum. And in vacuum a balloon falls as fast as everything else does. ",
"If you mean descending from an orbit above atmosphere into the atmosphere then a balloon would slow the fall theoretically because it would... |
[
"Why exactly does shaving foam keep a mirror from fogging up?"
] | [
false
] | Applying a thin layer of shaving foam on a mirror and wiping it off keeps the mirror from fogging up after a shower, which is very, very practical. My question is: What's the scientific reason behind it? | [
"Triethanolamine reduces surface tension, so a film of water forms instead of a bunch of droplets."
] | [
"Along with Triethanolamine being a surfactant, shaving foams contain oils which adhere to the surface of the mirror and create a hydrophobic barrier which inhibits water from binding to the surface of the mirror."
] | [
"It's the reason why baby-oil is a widely used mask defogger in scuba diving."
] |
[
"Why does your nose run when eating something spicy?"
] | [
false
] | null | [
"“Gustatory rhinitis” affects many people after they eat hot or spicy foods. When a person eats these foods, a nerve called the trigeminal sensory nerve is stimulated, which causes the nose to run. A person may prevent gustatory rhinitis by avoiding trigger foods.",
"Release of histamine, a nonspecific immunity m... | [
"Certain spicy compounds will trigger the TRPV1 receptors (capsaicin/vanilloid receptor) which can cause an inflammatory response due to perceived heat damage. That rush of blood to the face will warm up the sinuses and cause the mucus in them to become less viscous and flow out your nose and down into your throat.... | [
"It's your body hitting the \"EJECT\" button and trying to flush it out. remember, almost 2/3rds of your taste is carried by smell, so if you taste spicy peppers, you're getting the scent in your nose. ",
"So of course, your body hits the handle on the mucous toilet and flushes till that spicy turd's gone....... |
[
"Could we turn Jupiter into a Sun?"
] | [
false
] | null | [
"Looks like you need 13 Jupiter masses to be a Brown Dwarf star"
] | [
"I think this may have been asked before. The answer is: yes. The object would need to have about 80x jupiter's mass. ",
"Of course, at this point, the \"object\" would basically be replacing jupiter, as the original jupiter would only constitute a small portion of the new object. ",
"As a side note, there ... | [
"As an alternative to dumping 13 more Jupiters into Jupiter, as long as we're speculating on that level, you could put Jupiter into a magnetic jar and shrink it until it was about 1/3rd its current diameter. It would remain a star as long as the jar held. AFAIK, the energy to create such a magnetic jar far exceed... |
[
"Changing the speed of light"
] | [
false
] | null | [
"Changing it by 1% would probably not affect life a great deal, but it really depends on how you accomplish this. The speed of light may be derived as, for instance, a function of vacuum permeability and permittivity. Is it increased by 1% by changing each of those slightly? If so, perhaps this isn't very important... | [
"I was thinking not changing it as in humans doing it but simply a theoretical univers similar to ours with either of these two slight diferences. However I think the answer probably doesn't change much huh?"
] | [
"I was thinking not changing it as in humans doing it but simply a theoretical univers similar to ours with either of these two slight diferences. However I think the answer probably doesn't change much huh?"
] |
[
"What would happen if you light a match on a gas planet?"
] | [
false
] | null | [
"Nothing. ",
"On Jupiter, Saturn, Uranus, and Neptune there's no oxygen (O2) to sustain combustion. I doubt your match would even light in the first place.",
"Oxygen binds very readily with hydrogen and carbon to produce water (H2O) and carbon dioxide (CO2), which are more stable than diatomic oxygen. I only kn... | [
"Probably not. Nebulae are ",
" sparse from a human point of view. They generally contain around a thousand particles per cubic centimetre, give of take. For air, that number is something like 10",
" . If you were in the middle of a nebula, you wouldn't eve notice it, much less be able to light a match."
] | [
"Something akin to putting your eye right on your monitor. You see maybe 1 pixel at that distance. Now move 3 feet away, and you see the whole picture. ",
"Scale that up to cosmic distances... "
] |
[
"If the human ear can only hear frequncies up to about 20-22KHz, then what's the point of using a higher sampling rate in digital audio, such as 48KHz?"
] | [
false
] | [deleted] | [
"Any frequency above a certain point would work, and 44.1 kHz is kind of a weird number and was derived from TV frame rate frequencies (245 x 60 x 3, based on # of lines in a TV field).",
"Since Blu-Ray isn't 60 fps or defined by alternatively scanned lines there isn't any reason to use some weird number like 44.... | [
"Any frequency above a certain point would work, and 44.1 kHz is kind of a weird number and was derived from TV frame rate frequencies (245 x 60 x 3, based on # of lines in a TV field).",
"Since Blu-Ray isn't 60 fps or defined by alternatively scanned lines there isn't any reason to use some weird number like 44.... | [
"Read what you said. The Nyquist theorem needs double the frequency, and humans can hear up to 20khz... =40khz minimum. At that sampling rate, there are bad modulation issues, so the sweet spot for playback was considered 44.1khz using 16 bits. Increased sampling and bitrate does improve the perceived quality of... |
[
"Why is the combustion engine still king of common transportation?"
] | [
false
] | It seems like we are so along in knowledge and technological advances, but yet we are still using these semi-primitive ways to get around. Why isn't the hydrogen cell around more commonly? Or other little-to-none emission types of engines? | [
"There are still a lot of problems with other types of motors. The most obvious is that the energy storage is super easy (comparably) for combustion engines.",
"Hydrogen is difficult to store. It diffuses through everything and has usually to be kept at very high pressures and/or very low temperatures. Furthermor... | [
"Gasoline provides the highest energy per weight of any fuel. And it is cheap even when you consider the refinery process. It is fairly safe and readily transported. Even with the inefficiencies of engines, it is the best all around fuel."
] | [
"Gasoline provides the highest energy per weight of any fuel.",
"This is incorrect. ",
"Gasoline ~46MJ/kg",
"Hydrogen 123MJ/kg",
"http://en.wikipedia.org/wiki/Energy_density"
] |
[
"(Scientific method) Acceptable hypotheses: dark energy and phlogiston"
] | [
false
] | I'm not sure how to phrase my question simply, so please forgive me for trying to explain by example. I also don't have any background in physics beyond the AP level, so maybe there are just some technical details I'm not getting. Consider if you were an early chemist, researching the properties of then-generally-accepted phlogiston. As you burn wood, sulphur, coal -- most anything -- their masses decrease as they release phlogiston. So far, so good: the theory is supported. Now you burn magnesium, and, surprise! The mass increases. At this point, I believe, it would be bad form, as far as the theory goes, to explain that, while wood contains phlogiston, magnesium contains "dark phlogiston" with negative mass. It's an ugly, unparsimonious attempt to save a failing theory. As I understand it, dark energy works something like repulsive gravity. We observe that, for most anything, gravity seems to hold, but the universe seems to repel itself. So my question essentially is, why is it then OK to postulate dark energy? | [
"First, \"dark energy\" is just the place-holder name we give to whatever is responsible for the observed expansion of space. A lot of research remains to be done to figure out just what it is, but expansion is definitely happening and in the meantime we need some way to refer to the effect.",
"Second, according ... | [
"I would disagree with your assessment that the \"dark phlogiston\" hypothesis would be an illegitimate hypothesis. In fact, it seems it would have been a very reasonable hypothesis to propose. To call such a proposal \"unparsimonious\" or \"ugly\" (always a tricky notion) reflects the perspective of someone who ... | [
"Dark energy isn't a thing, it's an observation. ",
" exists to push things apart, this isn't in significant dispute. ",
"You must name this effect, even if you don't know what it is. Dark could just as easily be substituted for almost any word, in this instance synonymous with mysterious. "
] |
[
"Do black holes cores emit photons that just can’t escape to the surface?"
] | [
false
] | null | [
"We have no evidence of what happens beyond the event horizon of a black hole so any answer is speculation.",
"The math of General Relativity suggests that the straight line paths (geodesics) through spacetime along which all objects travel, experience such extreme curvature due to gravity that beyond the event h... | [
"No. There is no direction they could emit photons into. Inside the black hole \"going outwards\" would be going back in time. You can't send a photon to last Tuesday. That is not an issue of Tuesday (the event horizon in this analogy) - the problem is that it's not even a direction in space."
] | [
"Space is still a manifold, so locally Euclidean, so you could “turn around” and start out in a different local direction. Your path would still terminate at the singularity, of course."
] |
[
"What would happen if water's surface tension was much stronger?"
] | [
false
] | I'm interested in how this would change the world around us and everyday life. What if the surface tension doubled? What if it was increased by a factor of ten? Edit: Clarification | [
"If the difference in surface tension was reflected in a difference in Hydrogen bond strength, then changing it could have a huge impact on life. DNA pairs by hydrogen bonding and protein structures also often contain regions that are H-bonded to other regions in the protein, helping them to fold into their 3D str... | [
"Since we're here: From what I can look on the web, mercury is the liquid with the highest surface tension (5 to 10 times larger than most other fluids). Is this correct or is there something exotic with even higher tension?"
] | [
"Walmart would have to raise prices."
] |
[
"Do mosquitoes have a preferred blood type?"
] | [
false
] | I'm asking because I'm usually the one in my dorm that gets surrounded by mosquitoes while my friends are relatively better off. Is it because of my blood type or does body odor has something to do with it? | [
"Not blood type, but CO2 levels in your breath, your skin temperature, lactic acid.",
"If you exercise, your skin temperature and lactic acid will be up, attracting mosquitoes. Do you happen to work out more often than your dorm mates?",
"https://abcnews.go.com/Health/things-make-mosquito-magnet/story?id=246768... | [
"Or drink more beer? That also attracts them"
] | [
"There have been studies that lead to type O blood being preferred. ",
"https://amp-timeinc-net.cdn.ampproject.org/v/amp.timeinc.net/time/3311624/why-mosquitoes-bite?amp_js_v=a2&_gsa=1&usqp=mq331AQHCAFYAYABAQ%3D%3D#referrer=https%3A%2F%2Fwww.google.com&_tf=From%20%251%24s"
] |
[
"Why is alcohol universally toxic to living things?"
] | [
false
] | null | [
"Generally speaking, alcohol (like ethanol) is a solvent meaning it changes the solubility of cellular macro molecules. These can be lipids in cellular membranes or proteins within a cell that can denature if their solubility is altered. As membrane integrity and protein function is essential for all living beings ... | [
"Just wanted to add,",
"The order of toxicity of macronutrients is as follows: (in decreasing toxicity)",
"ethanol --> carbohydrate --> protein --> fat",
"100% of ethanol is oxidized. Conversely, a significant portion of fat may not be and may thus be stored instead if ethanol and fat are ingested together wh... | [
"I choose the latter.",
"Uh, did you mean the former? Because the rest of this sentence sounds like you're saying that soda is much worse than beer."
] |
[
"Can a metal detector detect a higher amount of iron in our blood?"
] | [
false
] | For example if I eat mussels, which contain high amounts of iron, am I more likely to set of a metal detector? | [
"The answer to your question is yes, but not from food intake. There is a disorder called Hemochromatosis which results in a higher than normal iron content in the body. A normal person has ~4 grams of iron in their body, while someone suffering from Hemochromatosis might have up to 50 grams in their body. These... | [
"If they're losing blood, and you bleed them enough, the bleeding will stop..."
] | [
"Blood loss."
] |
[
"Was the cosmic background radiation ever visible?"
] | [
false
] | to be clear, the cosmic background radiation has been red shifted down to microwaves. so assuming that someone was there to see it, was it ever visible to the naked eye when it was in the visible light spectrum? | [
"The cosmic background radiation dates from when the universe cooled to a temperature of about 3000 K (cool enough when atoms could form; they're electrically neutral, and thus the universe becomes transparent, and so those photons form background radiation from that point forward).",
"If you look at ",
"this i... | [
"\"",
" shifted\"",
"The background radiation you are talking about is thought to be the intense light left over from the big bang. So if you mean, \"did this light ever have a wavelength that falls within what we call the visual spectrum?\" then the answer is yes. But obviously no one was there to view it."
] | [
"Ah, thanks for pointing out my typo. i made this post pre-coffee this morning so i didn't have my head on right.\ncheers"
] |
[
"Would a half gram of U-238 with a .2% concentration of decaying U-235 be safe to handle in a sealed glass jar?"
] | [
false
] | null | [
"Um, why do you ask? (Calls FBI.)",
"Yes. Natural uranium is .711% U-235, so you have some depleted uranium that is less radioactive than something you could theoretically find laying on the ground. Half a gram is not a large quantity. Perhaps someone will do the math for you, but it should be safe enough. T... | [
"Fresh nuclear fuel pellets (so, somewhat enriched) are handled without more protection than gloves all the time. I wouldn't think depleted uranium would require much more than the usual chemical safety precautions. You don't want to inhale or ingest it, but it should be fairly harmless externally. ",
"Edit: ",
... | [
"Both U-238 and U-235 undergoes alpha decay, which is the easiest mode of decay (to block) out of the three common radioactive mechanisms. In fact, it has trouble getting through air.",
"Edit: Fixed non-sensical wording."
] |
[
"Since the singularity of a black hole theoretically has infinite density, would sound then travel at infinite velocity through it?"
] | [
false
] | So because sound travels faster the higher the density of the material it travels through, would that mean, in theory, that sound travels at infinite speeds through the singularity of a black hole? | [
"Nothing can travel through the singularity, it has no spatial dimensions. There's nowhere to travel from or to."
] | [
"We don't know that it ",
" exist. What we have is a model that says \"stuff falls toward this one spot and there are no known forces that can stop it, so it all just collects at that one spot.\" If it had some size, then there would need to be some outward pressure holding the \"stuff\" up against the intense gr... | [
"It is infinitely dense from the outside, not from the inside. We don't know about how the inside works. You can say, in a way, that sound does travel infinitely fast in that we treat the singularity as a point. So the energy entering one side is on the other side."
] |
[
"Why is Optical interconnection faster?"
] | [
false
] | null | [
"The main performance increase in fiber-optic interconnects compared to say copper, is the bandwidth that is permitted by the medium, ie; the amount of data that can be travelling the cable at any given moment. (comparable to the width of a pipe carrying water)",
"This is due to fiber-optics using beams of light ... | [
"To expand on that a little, the ",
"capacity of a channel",
" is defined by the following equation (from the Shannon-Hartley theorem):",
"C = B * log2 (1 + S / N)",
"Where C is the capacity in bits/second, B is the bandwidth, S is the signal power and N is the noise power.",
"As bandwidth (B) increases, ... | [
"Do you mean bandwidth or latency?",
"For bandwidth, it's about modulation rate and Shannon, other posts have treated this quite well.",
"For latency, the term you're looking for is \"propagation velocity\" or \"velocity factor\". In this respect, copper and fiber are very similar, both vary (depending on const... |
[
"Can time be subdivided infinitely?"
] | [
false
] | Similarly, is there a time measurement equivalent to the planck length? | [
"Nobody knows the answer to whether time can be subdivided infinitely.",
"Yes, there is a Planck time, but whether this is the minimal unit of time is not known. The various Planck scales are simply the scales at which quantum field theory and general relativity must both be included, and so the theory of what h... | [
"The Planck Time",
" is the time it takes light to travel one Planck Length."
] | [
"neither/both? Essentially, one of the biggest problems about the math is that we just have no (or very little) data to guide us with what that math should look like. As we'd develop the technology to probe those regions closer, we may get the necessary data to inform us on how to do the maths. So I'd imagine that ... |
[
"Has anyone ever tried to properly educate any non human species?"
] | [
false
] | null | [
"No non-human animal has language."
] | [
"But you don't ",
" language to teach. Besides we don't need them to speak a human language. If we made them a language that they could speak we could just translate it. As long as their teacher could understand their language and they could understand ours, we wouldn't need to speak the same language. "
] | [
"They have no capacity for any kind of language in the way that we do. There is no language they could speak or sign with. "
] |
[
"How do brain-eating amoebas (e.g. Naegleria fowleri, Balamuthia, etc) know the way to the olfactory bulb after binding to the mucosa?"
] | [
false
] | null | [
"The olfactory nerves exit the skull into your nose thru the cribriform plate. It's just a thin bone with tons of tiny holes in it for the nerve fibers. Naegleria has a flagella tail so if you accidentally \"snort\" it up your nose when you are in contaminated water, the protozoan can swim up and enter thru the cri... | [
"Thanks. Im'a never swim again in any water that is not at least 2% bleach by volume."
] | [
"Imagine that people use Neti pots with tap water sometimes from unreliable sources"
] |
[
"Is it advances in sheet metal molding that has enabled us to manufacture better looking, modern cars? Or is there something fundamentally different about how we think about aesthetics? Like a cultural difference?"
] | [
false
] | null | [
"The front end differences as AdShea mention.",
"Also there is a minimum amount of empty space above the engine to ensure a pedestrian's head cannot hit the top of the cylinder head.",
"There's probably other things I'm not aware of but those are certainly the bigger things."
] | [
"Modern car design is based around a few things...",
"Obviously not an exhaustive list but essentially design considerations are behind a lot of modern automotive aesthetic.",
"There is a certain aesthetic that some manufacturers try to achieve. For example white tough looking cars are \"in\" at the moment. Tha... | [
"I've seen this mentioned a lot on car literature but never really seen specifically what the pedestrian safety features are of the newer cars? it's still a many thousand pound metal object hitting a person at high speed, and odds are not good whether it's a 70's caddy or a '13 accord? "
] |
[
"Efficiency of heaters"
] | [
false
] | Is a fan forced element heater less efficient then a oil heater? Completely energy sealed room vs normal room | [
"On the other hand, ",
" (for heating, in this case) is more effective than any other heater. Why? Because although oil/fan/electric heaters all turn 100% of the energy you invest into heat, air conditioners actually use your energy to ",
" and put it into the room - so in addition to all the energy you spent b... | [
"On the other hand, ",
" (for heating, in this case) is more effective than any other heater. Why? Because although oil/fan/electric heaters all turn 100% of the energy you invest into heat, air conditioners actually use your energy to ",
" and put it into the room - so in addition to all the energy you spent b... | [
"yea you're right about the air conditioning reverse cycle being more efficient by moving more heat than it creates. you can get carnot cycle efficiencys beyond 200% depending on the volumetric efficiency of the refrigerant you've chosen and its mollier graph. \nair con has a huge isentropic efficiecy compared to m... |
[
"Are visual inputs in the center of your retina processed and perceived faster than those in your retina's periphery?"
] | [
false
] | Ok, so perfect example: I'm sitting here in my car looking at my phone, scrolling up and down Reddit. In the upper left corner of my left eye, I can see my phone's reflection in my left front window. Now, I SWEAR TO GOD, I'm seeing the reflection in the corner of my eye happen slightly the scrolling that I see happening on my phone in the center of my vision. Like maybe a few miliseconds after. Every time I scroll. Now, assuming light speed is too fast to notice this difference, my guess is the time dilation happens in my brain somewhere. I know the fovea is the most sensitive part of vision. But, is it actually so important to survival that the brain processes information in the fovea it processes information outside the fovea? Meaning, we become consciously aware of phenomena from our fovea before we become aware of phenomena from outside our foveas? So, am I crazy? Or, am I really seeing the same event essentially happen twice in my head due to seeing it from different places in my eye? | [
"Signal transduction in wires is slower than light, sometimes by a fairly significant fraction. Signal transduction in nerves is even slower because nerves don’t work like wires."
] | [
"This may be a similar phenomenon to the one where the second hand of an analog clock sometimes seems to skip a second. During a ",
"saccade",
", we are functionally blind for a brief moment, as the visual information would be too motion-blurred to make any sense. So our brains just extrapolate from past data s... | [
"I know a lot of fact about eyes and i never heard something like that.. After, the \"nervous flow\" is electric and as fast as light so it's not caused by the difference distance between the fovea, the periphery and the blindspot. Finally, each cells can be placed in a \"bit map\" so if the brain (can) do(es) that... |
[
"How can California be in a drought when they're next to an ocean?"
] | [
false
] | [deleted] | [
"The technology you're referring to is called desalination and it does exist.",
"Through techniques like reverse osmosis, we can very effectively turn ocean water into drinkable water, and there are plants in operation that do this. The problem is that these plant cost massive amounts of money and take tremendous... | [
"Yessir, plain ol' evaporation is the most common version of desalinization! The problem is (as mentioned before), it takes a lot of heat to evaporate all of that water. Californians use water at about the same rate as the flow rate of the Nile river (around 100 km",
" /year), so imagine what the engineering pr... | [
"Desalination is expensive",
":",
"Most projects are small, capable of providing less than three million gallons per day, often for rural areas. The state’s largest is in El Paso, where the $91 million Kay Bailey Hutchison Desalination Plant, completed in 2007, can supply up to 27.5 million gallons of water a d... |
[
"Total internal reflection question."
] | [
false
] | Let's say the critical angle or an incident ray going from one medium to a medium with a higher index of refraction is 60 degrees. Any incident angle smaller than 60 degrees will simply refract through the second medium, while at exactly 60 degrees the refracted ray is parallel to the plane between the media. Now we also know for incident angles greater than 60 degrees total internal reflection will occur. Such that a 70 degree incident ray results in a 70 degree (with respect to normal) internally reflected ray. My question comes from what happens in the differential increase from 60 degrees up to some arbitrary value, like 70 degrees for example. At exactly 60 degrees incidence, the "resultant" ray is parallel to the surface junction; in other words it has an angle of 90 with respect to normal. But at even 61 degrees this resultant/reflected angle becomes 61 degrees. In this short change incident angle (of just 1 degree) we lowered resultant angle by 29. How did this happen? Is the resultant degree non continuous for that region, because it is for all other values greater than the critical angle right? E.g. 70 degree incidence results in 70 degree reflection, 80 for 80... all continuous up to 90 of course. I know this is a bit lengthy and maybe even a bit arbitrary... but I'm just curious; thanks anyway! | [
"At angles below the critical angle not all of the light will be transmitted into the second medium. There's something called the coefficient of Reflection (and a related coefficient of transmission), which can be calculated with fresnel's equations. See: ",
"http://en.wikipedia.org/wiki/Fresnel_equations",
"If... | [
"Link",
" to a simulation I created that allows you to explore total internal reflection. Just set n2 to a value smaller than n1 and then vary the angle of incidence. Watch the percentages of light reflected and transmitted (simulation requires Java).\n",
"iPad friendly version"
] | [
"You are awesome!"
] |
[
"Do people in large population-dense cities like Tokyo, Mexico City and New York get sick more frequently, being exposed to more people on a daily basis?"
] | [
false
] | Related question: do they end up with stronger immune systems for the same reason? | [
"Short answer is yes and possibly. More people touching more areas allows for a greater spread of any bacteria. More hosts allow for a greater chance of mutation and more strains. Each time you contract a strain, even if it doesn't make you physically sick causes your body to create antibodies, thus theoretically b... | [
"The fact that there is some increase in illness isn't surprising. Really, it's interesting that there isn't a MORE striking increase. That's fortunate given our proclivity to live close to one another. "
] | [
"The increase is definitely noticeable during flu season or among children in those types of locations. With the recent increase in anti-vaccination beliefs, cities are at the highest risk of epidemic outbreaks."
] |
[
"Has anything changed in the last 20 years to make the forecasting of weather more accurate?"
] | [
false
] | So I was sitting on my deck and I was looked at my weather app at 11:30. It said that at 12:00 pm there will be a 100% chance of rain. The rain started at 11:50. Is this just a case of weather forecasts being more accurate closer to the event, or has something in the way that weather is forecast fundamentally improved? | [
"Now you can get customized forecasts based on your GPS coordinates instead of just your region or town. Radar and instrumentation has also improved over the years. Still, my weather app is wrong almost as often as it is right when it comes to rain forecasts."
] | [
"You’ll have to specify if you refer to a specific region in the world or if you look at average forecast quality in general. ",
"Weather forecasting is wildly different from region to region. Coastal vs. inland, flat regions va. regions with mountains, regions with lots of lakes and other water vs. with none, ar... | [
"It’s a matter of the app knowing your exact location and the current track of storms. It’s common for my app to send me lightning alerts as well as, “rain will be starting in X minutes”. ",
"To answer your overall question, some of the biggest advancements in weather forecasting has come from the launches of n... |
[
"How does cold welding work? What causes the metal to fuse?"
] | [
false
] | I recently read about how cold welding is possible in a vacuum while reading about some space type stuff, but I'm unable to dig up / understand the specifics behind this. | [
"If you have two metal surfaces that are extremely clean and well matched, you can compress them together very tightly to make a cold weld. The atoms at the interface start to diffuse and intermingle with one another, resulting in one solid piece of metal.",
"If you cut a metal block in vacuum, you will reveal a ... | [
"No, whole atoms will move. There are some animations of this ",
"here",
"."
] | [
"ok I can wrap my head around that. am I correct in assuming that when you mention atoms diffusing it's primarily electrons?"
] |
[
"In the double slit experiment, the peaks and troughs cancel out from the light from the two slits. Why does the peak and trough from a single slit not cancel out on the display screen?"
] | [
false
] | I was just thinking of the double slit experiment... We're told (and can see) in the experiments that the waves of light travelling offset from each other cancel out, or reinforce each other... If so - how come we can see any light coming from a single slit? How come it's not got a net brightness of zero, if the wave's troughs and peaks are hitting a screen? What about two light sources and two slits overlaid? Where's the waves go? Surely both sets of light create their own waves and troughs that can still interact? It seems they only exist when light's "split" into two from a single source? It's all very confusing... | [
"The peaks and troughs from a single slit do cancel out, this produces what is called a diffraction pattern. It is not completely dark, but it does have alternating light and dark spots.",
"In general, the intensity of light a particular point is due to the amplitudes of light at that point from all possible sour... | [
"Oh! I didn't suspect that! I thought there may have been something deeper happening - in a deeper dimension than usual."
] | [
"How come it's not got a net brightness of zero, if the wave's troughs and peaks are hitting a screen?",
"The \"brightness\" is proportionnal to the square of the amplitude of the EM field. In average the EM field is 0, but not the \"brighness\".",
"It seems they only exist when light's \"split\" into two from ... |
[
"What are the unique detriments to a Guaranteed Minimum Income?"
] | [
false
] | [deleted] | [
"Indeed. A guaranteed income needs to not be based on any additional income. You should get that 15k on top of anything else you decide to earn, it should be like your allowance for being a citizen, not something that gets sucked away whenever you put forth effort to try and better yourself.",
"On the plus side t... | [
"Indeed. A guaranteed income needs to not be based on any additional income. You should get that 15k on top of anything else you decide to earn, it should be like your allowance for being a citizen, not something that gets sucked away whenever you put forth effort to try and better yourself.",
"On the plus side t... | [
"Marginal Revolution has a take on this question from just days ago:",
"http://marginalrevolution.com/marginalrevolution/2013/11/what-are-some-of-the-biggest-problems-with-a-guaranteed-annual-income.html",
"Basically, while basic income could simplify and reap large savings for the entire welfare system, we act... |
[
"How come the undersea earthquakes and plate movements don't release oil into the environment under the oceans?"
] | [
false
] | null | [
"Oil seeps",
" are naturally occurring undersea oil leaks. They occur in many areas, often with oil wells there too. Oil well operators will often try to blame their own leaks on naturally occurring leaks (and not fix their leaks). My main point: It doesn't take an earthquake to leak oil from the sea bottom. In s... | [
"There are methane clathrates all over the ocean bottoms in oil producing areas. At the pressure and temperature of the sea bottoms, methane forms into an ice-like mineral with water. The crystals are clear and look like ice. The methane forms weak bonds with water and effectively raises the freezing temperature of... | [
"That's wild, In undersea vents I read that they found a flatworm that was like eating frozen methane or something like that.\nI wonder if there are any natural animals or microbes that are found around Oil seeps?"
] |
[
"How come we can't efficiently cool something quickly?"
] | [
false
] | I know there's things that can supercool stuff pretty much instantly, but ho come there isn't like a microwave equivalent for cold? Refrigerators/freezers usually take hours to cool something. | [
"The biggest reason is that it's much easier to turn useful energy into heat than it is to do the reverse. This is a direct consequence of the ",
"Second law of thermodynamics",
", which can be restated in simple terms as: \"You can't build an isolated device that converts its own heat into useful energy.\" On ... | [
"On the molecular level, it's a lot easier to speed up the molecules in something moving than it is to slow them down. There are a million different ways you can heat something up. Convection and conduction interactions between the object and the atmosphere, chemical reactions, radiation exposure, electric currents... | [
"Nowhere close to a scientist here. Just took his question to mean cooling food rapidly, which can and is done, a lot of people aren't aware of blast freezers because they are really only used commercially."
] |
[
"What causes one chemical to be classified as addictive and another chemical with the same effects non-addictive?"
] | [
false
] | For instance there are painkillers that are considered to be addictive and some that are not. What makes this so? | [
"I'll chip in. This is hard to explain but I'm gonna try my best. ",
"A lot of brain altering substances work by blocking neurotransmitters. (You'd be shocked how many drugs do this!) So what makes your regular old prozac (fluoxetine) and cocaine. Prozac is an SSRI, which means it blocks the brain from reuptaking... | [
"This is not my field so someone else feel free to correct me, but I believe it is the idea of psychologically addictive vs physically addictive. You can argue that all pain killers (among other things) are addictive but I am under the impression those classified as addictive chemicals are physically addictive. "
] | [
"Excellent points! I was more curious about the biology of physical addiction. I suppose I should have been more specific. "
] |
[
"What's wrong with these Homeopathy studies?"
] | [
false
] | I've always believed homeopathy to be a pseudo-science, but yesterday someone provided me with a link to studies on homeopathy that seem to show that it has valid medical applications. List of all the studies: Here are a couple of examples from the list: - Triple blind trial, Significant improvements in patients with chronic fatigue syndrome using homeopathic methods - Double blind trial, found that homeopathy improved hayfever symptoms Most of these studies show that homeopathy works at least better than a placebo, and in some cases leads to significant improvement. I don't understand how this can be the case. Homeopathy seems to violate everything I know about chemistry, but these studies show that it works. What's your take on these studies? | [
"The first study states in their abstract that the results were not statistically significant. In any clinical trial you have errors due to the random nature of human response to treatment, so your sample size must be large enough to show that there is a statistically significant difference between two treatments.... | [
"Full meta-analysis's show that Homeopathy performs no better than a placebo.",
"http://www.cochrane.org/search/site/homeopathy",
"If you really want to find out the true results of soemthing you need a meta-analysis. This merges data from multiple trials (that have good methodology) into a single analysis. ",
... | [
"Try enough times and anything will ",
"look effective."
] |
[
"How accurate is radiation in fiction (e.g. irradiated cities)?"
] | [
false
] | Oftentimes in fiction or science fiction, the film, novel, or video game is set in a place where the setting is irradiated, such as a city that was hit by a nuclear bomb. How realistic (if at all) is it that certain areas could be more irradiated than others? Another example would be the Fallout games, where some areas have extremely lethal levels of radiation, despite the fact that the entire world was equally decimated. Also, some fiction has the survivors living underground and only occasionally make short trips to the surface; is it realistic to only need a gas mask for trips to the surface if the duration is short enough? At what point does greater protection become necessary? | [
"The portrayal of radiation in fiction is at best incredibly misleading and at worst outright false. Things like comic books and video games have helped contribute to the widespread (and misplaced, in my opinion) public fear of radiation. Most of the pop-media portrayals of radiation effects, like glowing green o... | [
"Thanks for the reply. If the air was irradiated and toxic to humans, would you be able to tell just by breathing it, or would it seem completely like normal air?"
] | [
"You usually wouldn't be able to tell. The exception is if you had a specific radioactive gas that had a scent or if a smell was added to it (like natural gas in your house)",
"I work in a nuclear plant. You don't 'feel' or sense radiation at all. "
] |
[
"Do long-time smokers have a better chance of surviving smoke inhalation than non-smokers?"
] | [
false
] | Title says it all really. Are they better off in the situation of a house/building fire? Or worse off even? Or are they simply just as susceptible as non-smokers? | [
"Smokers need oxygen just as much as the rest of us. When they smoke, they are essentially replacing part of their inhale with smoke. ",
"Your question appears to be asking if one can build an 'immunity' to smoke inhalation, that enables a smoke to go longer without air... ",
"It would be the exact opposite. ... | [
"It's a bit anecdotal. Basically, smoking isn't gong to prevent you suffocating, which is what kills in a fire. The smoke itself doesn't do anything to your lungs, it's the lack of oxygen."
] | [
"It's a bit anecdotal. Basically, smoking isn't gong to prevent you suffocating, which is what kills in a fire. The smoke itself doesn't do anything to your lungs, it's the lack of oxygen."
] |
[
"What are some examples of reversible chemical reactions?"
] | [
false
] | I know there are physical changes such as water changing its state from ice to liquid water which can be easily reversed (changing the liquid water back into solid, ice form). I remember reading in a science textbook that chemical reactions are not so easily reversed, however. Are there any examples of everyday chemical reactions that can be easily reversed? | [
"Dissolution is one that comes to mind. Dissolve salt in water and then cool the water down and the salt will begin to precipitate out. \nIf that isn't \"chemical\" enough, then you can think of the same thing about carbon dioxide. When CO2 dissolves in water it follows the reaction CO2 + H2O = H2CO3, known as carb... | [
"One example everyday chemical reaction is the charging an discharging of batteries. A redox electrochemical reaction",
"Not to get too much on the complex chemistry of modern lithium ion batteries. Here a summary:",
"A typical Li-Ion battery discharges (when used) undergoes a reversible reaction where lithium ... | [
"Not a very helpful answer but every reaction is reversible, its just that in the case of what we call irreversible reactions the equilibrium so far toward the products that the concentration of reactant species is negligible.",
"The best example I can think of for a reversible reaction in the way we mean it most... |
[
"Schroedinger equation and wavefunction"
] | [
false
] | Schroedinger's equation contains the imaginary unit, i, and the solution (wavefunction psi) is a complex function. Indeed, Roger Penrose devotes pages in his books to develop and comment on the use of complex quantities in quantum physics....seemingly to say that somehow, complex quantities are needed to describe the physical world. In fact, a little math shows that the Schroedinger equation can be expressed as a pair of coupled real equations whose solutions are the real and the imaginary parts of the complex wavefunction, psi. Just substitute psi = psireal +i psiimag into Schreodinger's equation to find the two real, coupled equations. (psireal and psiimag are, respectively, the real and the imaginary parts of psi.) So it seems to me that in principle there is no need to use complex quantities in quantum physics. Perhaps the use of complex quantities is simply a convenient mathematical tool? I am really puzzled why this is not mentioned by Penrose or other quantum physicists. Am I missing something important? | [
"So it seems to me that in principle there is no need to use complex quantities in quantum physics.",
"It's true that one could use two real-valued equations to represent the original complex values and terms. But that would be more difficult, the math would be more involved, and the outcome would be less intuiti... | [
"So it seems to me that in principle there is no need to use complex quantities in quantum physics.",
"Pretty much, yeah. You could always reformulate them in terms of real and imaginary coordinates, psi would be a length 2 vector consisting of the real and imaginary part of our current formulation. Replace every... | [
"Thanks, lutusp. You have answered my question. We use complex functions for the same reason in electrical engineering. As you said, real functions could be used, but the math would be more involved etc. I just had not seen anyone say this wrt Schroedinger's equations and its solutions ....i am glad to get this... |
[
"If I started a fire and then fed it nothing but damp cardboard, would the energy in the cardboard be enough to keep it going despite the water?"
] | [
false
] | null | [
"Water has a specific (quite high) heat capacity, which means it takes a certain amount of thermal energy to saturate it to the point it boils away.",
"If the global heat capacity of the water in the cardboard is greater than the thermal energy you get by burning the dried up mass, you're not breaking even and th... | [
"I agree with your analysis, but it doesn't really answer my question. It does clarify the question though:",
"Is the global heat capacity of the water in damp cardboard greater than the thermal energy from burning the dried mass?"
] | [
"\"damp cardboard\" a bit too much of an umbrella term for a proper calculation.\nThe type of cardboard can vary the amount of water it can hold by probably an order of magnitude (think about how many ways the paper can be folded in the layers, depending on what features the manufacturer is after).",
"If you're t... |
[
"Why does hot water sound different when it's poured?"
] | [
false
] | null | [
"The viscosity of water changes significantly with temperature (hot water \"flows easier\" than cold water). Viscosity and speed of sound are related, and the propagation speed of sound waves is an important factor in the sound it makes when poured."
] | [
"No, viscosity is not related to density. Water's densitiy is not constant, but the variation is not that high, and much less noticeable than the variation in viscosity."
] | [
"It always seemed intuitive to me that density and viscosity would be related. Mercury is a great counterexample to keep in mind."
] |
[
"Why does gas-stove and electric stove cook foods differently, even though they are both indirect?"
] | [
false
] | null | [
"IANAS but I imagine it's because of the distribution of heat on the pan, as well as the speed at which the temperature can change."
] | [
"This seems correct. I've cooked with both and gas seems to have the great benefit of quick temperature change."
] | [
"Chef here. That is correct. Also, whenever you add food to a hot pan, the temp drops. When using gas, its easier to maintain the heat. It's much easier to get that golden crust on scallops using gas. "
] |
[
"How powerful must a laser be in order to see the beam in air?"
] | [
false
] | I know it's a function of how hot the air gets before it starts to glow, so how powerful of a beam would it take to make it visible in daylight? EDIT: To clarify, I was watching a video of a Naval vessel firing a laser at a target. The beam was invisible, but the target exploded almost instantly. How powerful would that laser have to be for the beam to glow bright enough to see with the naked eye in broad daylight? | [
"Maybe you should clarify your question -- do you mean a hypothetical scenario in which the air is totally free of dust, or do you just mean in practice? In practice it depends on the color of the laser, but roughly speaking you can (barely) see the beam above around 20 mW or so in daylight. "
] | [
"Yes in a vacuum in would be invisible regardless of wattage. But ordinary air is filled with dust (sometimes this is really obvious if light comes through a window in your house at the right angle), which reflects light. "
] | [
"It depends on the wavelength, but in clean dry air you get air breakdown with around a TW per cm",
" so maybe around 100 MW for the usual beam profile of a laser pointer. But with the right kind of dust you can initiate breakdown much lower, and I think it just depends on the size and type of dust that's in your... |
[
"If the level of energy in the universe is constant, how is it that it is constantly expanding ?"
] | [
false
] | [deleted] | [
"There's no real reason to suspect that energy is conserved in the universe. Conservation of energy is a consequence of certain symmetries of a system (specifically time translation symmetry), and an expanding universe does not ",
" that symmetry."
] | [
"expanding is easy, it's the accelerating part that's a bit trickier. if you assume energy is constant, it is still being reorganized into different forms. These different forms can cause the universe to expand and cool down simultaneously. No physics violated :)",
"In string theory, things get a bit weirder. ... | [
"Galaxies do die out, because they throw all of their energy out into space as heat, and since the universe is expanding, but cannot gain energy the AVERAGE temperature of the universe is becoming colder."
] |
[
"If meditation is good for the brain, is the opposite of mediation(chaotic, unfocused thoughts) bad for the brain?"
] | [
false
] | null | [
"I think you're going to have to explain your premise before anyone can answer your question. In what way do you think meditation is \"good\" for the brain? Do you have a source that states that meditation is \"good for the brain\" so we can form an objective definition for what that might mean?"
] | [
"The source you provided doesn't suggest that meditation only reduces symptoms in those with illness already - \"Among healthy subjects, 5 RCT’s were performed in 247 students[36]. Anxiety decreased significantly compared to students that did not receive MBSR,...\". ",
"And even more importantly, they only evalu... | [
"Thus, the 'opposite' of mediation would also do nothing. ",
"In the best interests of OP, I would suggest that you don't jump unscientific conclusions like that. You may well have sources that suggest that meditation does not have a positive effect anyway - but that doesn't necessarily mean the opposite is true... |
[
"Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Please only answer a posted question if you are an expert in the field. . In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for . If you would like to become a member of the AskScience panel, . Past AskAnythingWednesday posts . Ask away! | [
"[deleted]",
"\n ",
"This comment has been overwritten by ",
"this open source script",
" to protect this user's privacy. The purpose of this script is to help protect users from doxing, stalking, and harassment. It also helps prevent mods from profiling and censoring. ",
"If you would like to protect ... | [
"The Big Bang Theory is pretty simple, and extremely general. It says that in the distant past the universe was a hot dense almost featureless soup of particles. This expanded and cooled, and the material fragmented into galaxies, stars, planets, etc.",
"We can directly see back to when the universe was hot, dens... | [
"Is it possible that on a large enough scale our universe is in a \"solid\" state?",
"Just as my desktop appears solid but is largely empty space - as our known universe is."
] |
[
"How come we see the Milky Way almost as though we’re outside of it?"
] | [
false
] | null | [
"The galaxy is flattish and you can see along it... I'm not sure what you mean exactly. You are inside your room and can see the room"
] | [
"Do you mean why is it only a strip and not taking up the entire sky? That's because it is \"flat\" like a disc. There are some renderings ",
"here",
" that might help"
] | [
"No worries =) sorry if I didn't understand your initial question"
] |
[
"How much does covering your mouth with a hand/scarf etc or mask protect you from pathogens?"
] | [
false
] | [deleted] | [
"It varies with the pathogen and whether it is truly airborne or just aerosol (that is, contained within tiny droplets of water). Aerosols are generally mostly blocked by any mask/scarf, while truly airborne pathogens are nowhere near as affected.",
"Note that unless the mask/scarf is washed fairly quickly after... | [
"It's actually to stop the wearer making others sick and not to avoid getting ill himself (for which it has no effect). Western hospitals use them for the same reason."
] | [
"Agreed, but while its purpose isn't to provide protection to the wearer, it does provide a small amount."
] |
[
"Does the total volume of precipitation in the sky vary? If so, by how much?"
] | [
false
] | null | [
"Unsure what you are asking. Are you asking if the amount of water vapor varies? If so, it clearly does because humidity varies widely over the Earth."
] | [
"Yes, I'm asking about water vapor in the air. Is it possible to find out the ranges of vapor?"
] | [
"This in no way my expertise... perhaps start with ",
"http://en.wikipedia.org/wiki/Water_vapor",
". This article states:",
"Gaseous water represents a small but environmentally significant constituent of the atmosphere. The percentage water vapor in surface air varies from a trace in desert regions to about ... |
[
"Can one \"burn off\" ingested caffeine? (Or other drugs)"
] | [
false
] | If 2 people drank a cup of caffeinated coffee (or whatever method you prefer) that had X milligrams, one (person A) remained sedentary for the day and the other (person B) exercised rigorously (a good 2-4 hours worth) throughout the day, would the caffeine stay in both their systems for the same amount of time or would Person B 'use' it faster? | [
"Mainly decomposed by CYP1A2 in liver"
] | [
"Not really. Most drugs are broken down and/or excreted by the liver & kidneys as the main method of excretion. They don't normally get used up because they act like catalysts for physiological processes rather than being directly involved in them. For example caffeine gives the perception of having more energy and... | [
"Wouldn't increase in circulation rate lead to more blood going through the liver, more enzyme exposure and faster decomposition? Or might the exercise actually divert blood flow to the periphery and away from the liver?"
] |
[
"I know you can donate your body to science, but what about your death?"
] | [
false
] | null | [
"It wasn't just about the legality of voluntary death, but about making sure you cop it while in the tube, which practically speaking means someone pushing a death button, in my mind."
] | [
"Right, that's what I mean by palliative treatment. Hospice doesn't extend the lives of its patients; it merely provides them with comfort while they decline."
] | [
"Right, that's what I mean by palliative treatment. Hospice doesn't extend the lives of its patients; it merely provides them with comfort while they decline."
] |
[
"When two people are infected with the same virus, are the t cells in our bodies that deal with the virus the same?"
] | [
false
] | I only have a simple understanding of how the immune system works, but I learnt about the lock and key model that describes the way in which t cells operate. From what I know, a specific t cell will attack the virus depending on the antigen (?). If this is the case then would two separate immune systems identify the antigen in the same way and thus would the t cells be the same? | [
"Nice to see some immunology on here!",
"No. The concept of V(D)J recombination and there being \"one epitope for one clonotype\" of T cell was soundly struck down a few years ago. I, like you, however, was still taught the same dogma you've been taught. ",
"The clonal selection theory proposes that individual ... | [
"B cells and monocytes are the \"professional\" antigen presenting cells (and to some extent dendritic cells, but they're a v small percentage of total white cells). They endocytose and present peptide fragments on MHC classes I and II, endogenous and exogenous respectively. The T cells then recognise the antigens ... | [
"B Cells are the ones doing the antigen recognition, not T cells. I thought?"
] |
[
"Can I always use the Heisenberg uncertainty principle to understand diffraction?"
] | [
false
] | What happens in a single-slit diffraction experiment when the slit width "d" becomes narrower than the wavelength of the light? To put the question in more context, when I was an undergraduate I once heard that single-slit diffraction could be understood in terms of the Heisenberg uncertainty principle. The argument goes as follows: Imagine an incident plane wave of light at wavelength "λ" approaching a 1-dimensional slit aperture from the left, which I will define here as the "x" direction. The slit is of height "d" along the "y" direction, and for simplicity's sake is infinite along the z direction. Light must pass through the slit in the form of photons, and the Heisenberg uncertainty principle places limits on these photons' momenta. Specifically, we know that as a photon passes through the slit, its vertical position is known to within an uncertainty of about "d" so the vertical component of momentum, "p_y", is only defined to within a precision of about hbar / d. Now, because the incident light was coming in with wavelength λ, we know that each photon’s total momentum must be roughly 2 π hbar / λ. We can combine the two relationships to give the following relation, d sin(theta) = λ. (sin(theta) = transverse photon momentum / total photon momentum.) This is exactly the condition for the edge of the central peak in Fraunhofer diffraction. My question is this: What happens when the slit becomes narrower than λ? That is to say, what happens when the slit becomes so narrow that a photon passing though it must acquire an uncertainty in transverse momentum that is greater than the photon’s total momentum was to begin with? At least two possibilities come to mind: (a) When the slit gets narrow, light simply cannot get through. This seems reasonable except for the fact that once you close down the slit even a single photon that sneaks through the slit would have to violate the uncertainty principle. Transmittance that is identically zero seems almost as difficult to swallow as a failure of the uncertainty principle. (c) When the slit becomes very narrow, it begins to resemble a cavity where photons can be up-converted to higher energy and momentum. Would this mean that forcing light to pass through a narrow slit changes its color? Thanks in advance for any thoughts. | [
"I wouldn't use the uncertainty principle to try to explain anything, to be honest. It's much better to look at the underlying principle, namely that of conjugate operators or, clasically speaking, Fourier transform relationships.",
"For a diffraction experiment, the resulting image in k-space (wave vector space)... | [
"I see the problem now, I'll have to give it some thought. The typical description relies on conservation of momentum and capping the available wavevectors to k (this is done by the relation k_y = |k|*sin(theta)). I've never really thought about how the uncertainty principle applies to this. I don't know if a small... | [
"Let me word the question a different way:",
"The Fourier transform of a slit of width = d is a distribution in k_y with standard deviation ~1/d. If d << λ, then the absolute value of transverse momentum for a typical photon passing through the slit is |k_y| >> 1/λ. How do we simultaneously understand this and th... |
[
"Which flow type cools faster, Laminar or Turbulent?"
] | [
false
] | If a copper rod is being cooled by a fan, and depending on its position it can experience both turbulent or Laminar flow, would the rod cool faster if the flow is more turbulent or laminar? The position the rod experiences laminar is closest to the cooling source, so intuitively this would cool faster, but experiment has shown that the further away from the source it is, and the more turbulent the flow, the faster it cools. Am I misunderstanding my results, or what is going on behind the physics? | [
"Laminar flow provides heat transfer only through conduction because in laminar flow the air is flowing in sheets with little mixing between them. A way to visualize this is a deck of playing cards. The layer of air that touches the rod is heated. That layer also does not mix with the other layers of air above it.... | [
"Thank you very much for the response. When you say that laminar flow provides heat transfer only through conduction, why is this? What you have said definitely makes sense in terms of my results. I'm new to the heat transfer stuff, and just the sheer number of angles you have to approach everything from and the vo... | [
"Thank you very much for the response. When you say that laminar flow provides heat transfer only through conduction, why is this? What you have said definitely makes sense in terms of my results. I'm new to the heat transfer stuff, and just the sheer number of angles you have to approach everything from and the vo... |
[
"If an object is colored in a color outside the visible light spectrum (ex: ultraviolet, infrared) would that object be perceived as invisible to us?"
] | [
false
] | null | [
"No. Objects that do not reflect light in the visible spectrum appear black."
] | [
"So does that mean anything that is black is actually colored a color outside the visible light spectrum? How can we tell if a black object is colored UV or infrared or any other invisible color?"
] | [
"An object that appears black to us may reflect light in wavelengths outside of the visible spectrum. We would need some sort of sensor to measure this that is sensitive in that range (an infrared or UV camera for example). ",
"In reality, no object perfectly absorbs all wavelengths in the visible spectrum."
] |
[
"What is the heaviest naturally forming element in the universe?"
] | [
false
] | null | [
"You don't need an estimate. Its Plutonium. No elements heavier than plutonium are known to occur naturally. That said, natural plutonium is so rare, for a long time it was thought to be only artificial. Uranium is the heaviest element created in appreciable quantities."
] | [
"Wikipedia, citing Emsley's \"Nature's Building Blocks\", suggests that elements up to ",
"Fermium",
" were produced naturally in the Oklo natural reactor.",
"I've also read elsewhere that some supernova could produce elements as heavy as Californium or Curium."
] | [
"According to ",
"THIS",
" blogpost on Scienceblogs, the one study that detected naturally occurring plutonium is \"not universally accepted\". His argument is that while plutonium could be created naturally, the supernovae that supplied our solar system with its heaviest elements was not energetic enough to do... |
[
"Do insects have thoughts or is it all pre-wired actions?"
] | [
false
] | [deleted] | [
"What's really gonna bake your noodle later is when you ask yourself \"When I see a predator and think 'I should hide because that thing can kill me', is that because ",
" wired that way?\".",
"So, yes. The process by which an insect determines a reaction to an aversive situation may involve fewer steps than a ... | [
"I am not an insect (to my knowledge), so I can't tell you for certain. FYI a conscience is not the same as consciousness; I doubt insects have strong moral leanings. And consciousness is hard to define, much less measure.",
"You're asking an interesting question, but the problem with these kinds of questions is ... | [
"But then consider a virus. Is the worm any more \"special\" than a virus? The worm is obviously more complex, but they both have the same \"thoughts;\"",
"I would argue that this isn't true. Viruses work, respond to their environment, and reproduce on largely a protein/nucleotide level. A worm has an extra level... |
[
"If a racquetball and a golfball are hit with a golf club against the wall of a racquetball court, which one will have the most speed/force when returning from the wall?"
] | [
false
] | So here is the setup. you have a golf ball and a racquetball on separate golf tees inside a racquetball court. They are struck with a golf club at the wall and bounce back. My question is which would be traveling at a greater speed ad have more force. My guess is that the answer has something to do with the bounciness (elasticity) of the balls. I would think that the racquetball would have more speed/force after hitting the wall because the golfball is much less elastic, causing it to transfer most of its energy to the wall. Correct if I'm wrong. I guess I derived this question from the "Jackass" boys. We were wondering which would hurt more, being struck by a racquetball or a golfball. The link to the video is posted below(Sorry for any crude language) | [
"The golf-ball collision is ",
" more elastic",
" than the raquetball one.",
"The raquetball being squishier actually has nothing to do with its elasticity, and everything to do with it's (lack of) stiffness. Both balls are almost completely elastic and return almost perfectly to their original shape after b... | [
"From an energy point of view it is correct that golf-ball would be worse for the person getting hit. From a force point of view (mass * acceleration) it is also worse for the person getting hit as the racket ball will decelerate over a greater length than the golf ball.",
"[note OP that since they have the same... | [
"Are we assuming that the golf ball will rebound perfectly off of the wall without damaging the wall? If you were to actually try this I believe that in most cases a golf ball would cause much damage to the wall and lose most of it's rebound through this damage."
] |
[
"What is the probability of TCP failing to detect an error?"
] | [
false
] | I am starting to learn about CRC and the TCP/IP stack protocol. Am I correct in thinking that, for as little as it may be, there is still a possibility that all of the error detection methods throughout the layers fail to discover a particular sequence of wrong bits? If so, is it an issue that programmers should take into consideration, when dealing with highly critical data? | [
"The TCP checksum isn't meant to guarantee anything, it's a pretty weak test, especially when you're talking about massive amounts of data. ",
"This",
" paper is pretty cool. Mostly you're relying on the fact that your data transmission protocols are pretty high-fidelity, so your base error rate is low, and the... | [
"I can't seem to access the paper, though I found ",
"this",
" web page describing the phenomenon. It actually cites your source, and estimates that",
"between 1 in 16 million and 1 in 10 billion TCP segments will have corrupt data and a correct TCP checksum",
"So that is actually quite a lot, isn't it? Any... | [
"Absolutely not - you can't guarantee an error-free connection, you can only guarantee one to a certain tolerance (probability of failure). In any case, not all bytes are created equal, so the consequences for an error rate of 1 in 10 billion is not necessarily that high. But if you've ever downloaded an ISO, you k... |
[
"During a severe asthma attack, why can't the patient resolve it with endogeneous release of epinephrine?"
] | [
false
] | During exercise-induced asthma, asthmatics can 'treat' bronchoconstriction while they are exercising due to epinephrine release. But when they stop, they can have an attack minutes later because there is no further release of epinephrine. My question is: why can't these patients release epinephrine because they are panicking/in a high stress situation, especially one that they know can cause them to die? Is this because they 'run out' of epinephrine in the adrenals? | [
"Doctor here.",
"Many asthma medications are Beta-2 receptor agonists--including albuterol. ",
"Beta-2",
" receptors are responsible for the smooth muscle relaxation that achieves symptomatic relief in asthmatics.",
"Epinephrine is non-selective and can cause myriad effects that differ based on high vs. lo... | [
"As an asthmatic that has been struggling with it all my life, I'm a bit intrigued by this as well. ",
"Something I'm curious about as well is why Cold air seems to help my asthma significantly. If I'm having a bad attack, and I'm somehow without my inhaler, going outside and taking big gulps of fresh cold air re... | [
"We will certainly use adrenaline infusions to treat asthma, but they are not first line, and as Shinkei says, more selective beta 2 receptors stimulating drugs are normally used first. However, in a severe attack even these may not be effective. Thats because part of the problem in asthma is not just the airways n... |
[
"How much potential energy could be produced using wind and solar means in the US if we took advantage of all the empty space?"
] | [
false
] | null | [
"that, combined with geothermal (properly harnessed) would make charging for energy obsolete as it would be so plentiful and ubiquitous. We're talking in the order of Zeta joules (the whole earth only uses about 1/2 a Zeta joule per year. "
] | [
"I can't speak for Solar, but there were two studies back in September - one from the Carnegie Institution for Science, which speculated that there's enough wind in the world for trillions of watts of power from Wind alone - 10 times the world's current 'need'.",
"However, the catch was they would need 100 new tu... | [
"The limitations to complete penetration of renewable energy are technical and economic. There is absolutely enough renewable energy potential capacity, even using current technologies, to meet global energy demands. The obstacles are cost and technical feasibility (e.g. if you build a giant grid composed of high... |
[
"Is there any difference between mass granted by the Higg's mechanism versus mass granted by the Strong force?"
] | [
false
] | Forgive my terminology, but as I understand it, the Higg's field creates mass for elementary particles, but the vast majority of mass we see is a result of the strong force holding together bundles of quarks and nucleons. How is it that these 2 seemingly different mechanisms result in something that on our scale look like exactly the same thing? Does mass created by the strong force interact with the Higg's field? Does mass created by the Higg's field interact with the curvature of spacetime? | [
"Is there any difference between mass granted by the Higg's mechanism versus mass granted by the Strong force?",
"No, there is no difference.",
"How is it that these 2 seemingly different mechanisms result in something that on our scale look like exactly the same thing?",
"Because both mechanisms are doing th... | [
"Photons in a box are a good place to start because they're simpler to picture than the Higgs mechanism. Move the mirrored box and the photon bounces off a moving mirror, blueshifting it. This costs energy so of course you get a force opposing your attempt to move the box.",
"You find that any way you look at it ... | [
"It's that simple all along? I've never heard that analogy before but it makes the idea of \"giving mass\" so much more plausible."
] |
[
"When would you clean with, say, vinegar or borax instead of dish soap or bleach or alcohol?"
] | [
false
] | What are the properties of common solvents used to clean things, and what about them makes one better or worse at certain jobs than another? | [
"Some of the substances you mention are solvents, and others aren't. ",
"Bleach and vinegar (acetic acid) chemically attack anorganic and some organic substances and destroy them. I don't know how Borax works. ",
"Dish soap is a surfactant, it is a long molecule with one polar (hydrophilic/lipohobic) and one ... | [
"Great answer, thanks! I'm off to imbibe some complex solvents😁"
] | [
"In addition to the above, vinegar works as a decalifying agent because much of the crust that develops on sinks and tea kettles is carbonate salts, which are very soluble in acidic solutions. The acid used doesn't have to be acetic acid, but it's readily available, and acetate is itself highly soluble, so it won't... |
[
"Prior to the existence of pollinating insects, how did plants reproduce sexually?"
] | [
false
] | null | [
"Pollen is a relatively recent invention. It evolved around the same time as the seed. The first types of pollination were almost certainly by wind -- there is clear evidence for this from fossil plants (their anatomy and morphology is consistent with wind pollination).",
"Your question is more broadly about sexu... | [
"Thank you for saying hypothesis instead of theory. It's so sad when people interchange them."
] | [
"Prior to evolving for specific insect types for pollination (eg. corollas for insects with long tongues), plants pollinated by wind. Actually some plants still do that today!",
"It is probable that brightly coloured flower petals that are attractive to insects evolved from dysfunctional stamen (the male reproduc... |
[
"What is the math behind mining bitcoins?"
] | [
false
] | What math does the computer do exactly to mine bitcoins? How do they make it to be harder and harder to mine and calculate so that you always end up needing more processing power? Why was it once relatively easy and now it is almost impossible to do decent mining with a desktop computer? | [
"What math does the computer do exactly to mine bitcoins? ",
"To \"mine\" coins you find an input to the SHA-256 hash function that produces an output that is less than some specified value. Since SHA-256 is a cryptographically secure hash function there is no way to predict the inputs that will produce a particu... | [
"The central calculation (also known as the \"",
"proof of work",
"\") involved in Bitcoin mining is the ",
"SHA-256",
" hash function (technically, two calculations of the hash).",
"When you mine BTC, what you're technically trying to do is create a new ",
"block",
". This is done by repeatedly hashi... | [
"The reward and benefit is having mined the coin. It becomes \"your\" coin and is entered into your Bitcoin wallet. Some places will accept Bitcoin as currency. It has value because the people who deal in it mutually agree it has value."
] |
[
"Why does a photon have an electric field?"
] | [
false
] | Or rather how does it have one? | [
"I think discussing the reverse question is more illuminating: ",
" ",
"From electromagnetic theory, we know the Lagrangian (an incredibly compact way to describe motion and energy in physics) is for chargeless situations, ",
"ℒ = -¼F",
"F",
" ",
"where 'i' and 'j' cycle through time, x, y z, and, "... | [
"The photon is nothing but a particular configuration of the field; a ripple in the field, if you will."
] | [
"More precisely, the field is ",
" photons."
] |
[
"At what point does motion become sufficiently microscopic such that it becomes tempurature?"
] | [
false
] | null | [
"A motion contributes to the temperature when it is in thermal equilibrium. Size doesn't matter in-itself. For translational motion, it will be in thermal equilibrium when it's randomly distributed. That is, the net motion of an object does not count towards its temperature. It doesn't matter if something is standi... | [
"The particle level for most familiar substances is molecules (or atoms for pure elements).",
"To me that suggests a certain amount of independence from scale, which is what I think the OP is trying to ask about. Are differences in temperature manifest at a subatomic / quantum level?",
"I'm open to being correc... | [
"Then they're oversimplifying to the extent of being wrong and you're taking some very introductory level courses. Temperature is defined by dU/dS = 1/T, and encompasses all energetic degrees of freedom. If you heat something enough, electronic excitations begin to occur. Does that mean the temperature drops as ene... |
[
"Why did the Apollo astronauts not just parachute from space directly? Why did they have to use the heat shield and then open the parachutes? And could someone conceivably skydive from the ISS?"
] | [
false
] | It seems like it would be possible to just "float" down from space on a parachute... | [
"The ISS is travelling at around 28000km/h (17000mph) relative to the Earth's surface. To land on the surface, that kinetic energy needs to be shed. The spacesuit (EMU) plus manned manoeuvring unit (MMU) have a combined mass of around ",
"190kg",
" (420 lbs). Combine this with an 85kg (185 lbs) astronaut and yo... | [
"And could someone conceivably skydive from the ISS?",
"If you're on the ISS, then you are in orbit. Jump from it, and you'll continue to orbit the earth for decades."
] | [
"Very true! That increases the power dissipation requirements by about an additional 10%."
] |
[
"How dangerous is uranium/uranium oxide to handle?"
] | [
false
] | At 38:55 of the below video, it is said that people wear gloves when handling uranium to protect the uranium from being contaminated, rather than wearing gloves to protect themselves from the uranium. It is said that since uranium's half-life is in the billions of years, it isn't that radioactive. This sounds hard for me to believe, as I thought uranium was very dangerous to handle. Is it true that uranium isn't that radioactive? That gloves are worn to protect the uranium, and not the human? Also, is uranium oxide - which is what the pellets in the video are - the same as uranium in terms of safety? | [
"Uranium in its natural state is not particularly radioactive. U-238 is the most common isotope in Uranium ore. U-235, the more radioactive isotope used in enriched and weapons-grade uranium only accounts for about 0.7% of natural uranium ore. But even U-235 isn't terribly dangerous from a radiation standpoint. The... | [
"I have never seen someone in a \"radiation suit\", and I work at a nuclear plant. What I have seen is people in anti-contamination clothing, which basically protects their skin and clothes from getting radioactive particles on them. Consider that typical lead shielding is one inch thick, and to give you 12 squar... | [
"Purified uranium metal or uranium oxide is chemically toxic (like lead) but not very radioactive. You can handle it. Don't eat it. Don't fill your house with it. But it's not very radioactive. Handle it like you'd handle lead — wash your hands after touching it, don't vaporize it and breath it in, etc. Uranium oxi... |
[
"Trying to learn about ultrasound and I get that sound is reflected at an interface proportional to the difference in acoustic impedance between the two materials but what I can't find is a physical explanation for why that would be the case. Can someone help?"
] | [
false
] | I find it especially weird that it works in both directions equally, for instance nearly 100% of sound is reflected going from air to solid AND solid to air. Why?? | [
"In one dimension, you can consider that your substances are a bit like a Newton's Cradle. Air has very light balls on long strings, a solid has heavy balls on short strings. It's a bit of a simplification, but the math comes pretty close to being a discretised version of the wave equation.",
"If a soundwave come... | [
"Because of the difference in impedance the waves will travel at different speeds in the two materials. Given this, and the fact that there has to be continuity of the wave fronts across the boundary separating the two materials, a reflected wave must exist. If it didn't then there'd be an unexplained discontinuity... | [
"That's an awesome explanation, thank you!"
] |
[
"How safe is handling a radioactive fragment of Chernobyl's nuclear fuel with bare hands? (video inside)"
] | [
false
] | In video, the girl finds what is purportedly a radioactive fragment of Chernobyl's nuclear fuel. She handles it with her bare hands and even takes it home. Is it safe to handle this with bare skin? If not, what protective gear should have been worn? What if the fragment was eaten or inhaled? Thank you rennovak for the additional questions: What effect does it have, if any, on the devices like the laptop, mobile phone etc? Is this fragment dangerous only from a nearby position or could my whole building be in danger if I would to take it home and keep it? | [
"First off, I would be highly skeptical of any YouTube video claiming to have found something like that. It is easy to make stuff up on the internet. ",
"But let's assume that the video is accurate: she claims the source she found has a contact dose rate of several Sv per hour. It seems like the source is most... | [
"The girl in the video posted a gamma ray spectrum of that very piece of fuel on Fusor.net, an amateur Fusion/radiation discussion board. ",
"The thread and discussion can be found here.",
"That individual piece wouldn't cause acute whole body harm, but I wouldn't want to sleep near it nor would I neglect to wa... | [
"You can read an AMA I did ",
"here",
". I work in a radiation oncology clinic."
] |
[
"When I'm hungry, I smell food better. Is that my brain filtering information differently or is it my nose being \"more active\"?"
] | [
false
] | null | [
"I don't experience this, but nonetheless it must be the former (your brain filtering the information differently).",
"There is no difference in the number or type of odor receptor cells or the \"activity\" of your olfactory epithelium in the roof of your nose between times when you are hungry and times when you ... | [
"My best guess: an evolutionary defense mechanism. When you're hungry, your brain focus more resources towards finding nourishment. It makes processes that would benefit you finding food in the wild a priority. A heightened sense of smell during hunger likely benefited a primitive human in search of food in the wil... | [
"As a neuroscientist, this is moreorless correct."
] |
[
"Is it possible (theoretically) to cause nuclear fusion through a purely kinetic method, or in layman's terms smash two objects together really hard to fuse them?"
] | [
false
] | null | [
"Yes, this was first done by Ernest Rutherford, who combined helium and nitrogen into oxygen."
] | [
"Yes, this is routinely done using accelerators."
] | [
"These are generally fixed-target machines rather than colliders. So the beam is shot onto a stationary target, and fusion reactions happen in the target."
] |
[
"Explain to me, in a nutshell, what Quantum Superposition is."
] | [
false
] | null | [
"First, you have to understand the concept of quantum states. Let me give you an example:",
"Take an ordinary photon. Any photon. And now this photon passes through a vertical polarizing filter. Now, there are two states that this photon can be in: vertically polarized, or horizontally polarized. If it's ve... | [
"In any quantum mechanical system, the state of the system is described by its wavefunction. This was the insight gained by the most important tool in quantum mechanics: the Schrödinger equation, whose solutions, given initial and boundary conditions, describe the probability distribution of observing the system in... | [
"Superposition is counter-intuitive, but not that mysterious in the formalism of quantum mechanics. The possible states of a quantum system are often characterised as \"directions\" in Hilbert space. The state of a given system might be a direction that can be written as a sum of two other \"directions\". It's ... |
[
"How small a particle can be effected by magnetism?"
] | [
false
] | What is the smallest individual particle that can be manipulated by magnetism? Would magneto be able to individually manipulate individual iron molecules? | [
"Mass and volume have absolutely no effect on magnetic force. Magnetic force is proportional to charge, strength of magnetic field, and velocity of particle. An ideal particle with no mass and no volume could still be affected by magnetic force. Yes, theoretically magneto could manipulate individual particles of ir... | [
"An electron is the smallest charged particle, and therefore the smallest particle that can be affected by magnetism. Magnetically deflecting electron beams is how CRT monitors and televisions work."
] | [
"Electrons are affected by magnetism, as was mentioned. There are hypothetical particles called axions that are about a millionth as massive as electrons, which would interact with magnetic fields."
] |
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