title stringlengths 4 300 | selftext stringlengths 0 9.63k | answers.text stringlengths 55 11.4k | answers.score int64 2 32.7k | title_urls.url list | selftext_urls.url list | answers_urls.url list | sent_vec list |
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debroglie wavelength question | all physics students know the debroglie wavelength equation \lambda = h/p, where \lambda is a wavelength, h is planck's constant, and p is momentum. the wavelength becomes important when mass is small very small, but i have always wondered what happens when velocity gets really small. is there an explanation why this i... | macroscopic object, component parts, infinitesimal fraction ====== to get a macroscopic object (and its component parts) to stand that still, you would have to cool it to an infinitesimal fraction of absolute zero. exercise: figure the kinetic energy a 1kg mass would have to have to have a debroglie wavelength of 1 met... | 3 | [] | [] | [] | [
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how is it stimulants make people feel energetic/awake? | so i have been curious about this. i know a little bit about how the energy is made for humans(atp), but how is it a stimulant like caffeine works on our body? is it all psychological? is it a trick it plays on our body? or some other thing that i am missing. thanks! | feeling energetic, actual amount, atp floating ====== feeling energetic or awake has little to do with the actual amount of the atp floating around in your cells. caffeine mainly does 2 things to cause the "wakeful" sensation that you feel: 1. caffeine acts as a mimicker of another neurotransmitter called adenosine, wh... | 7 | [] | [] | [] | [
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binary success of persistence in weather forecasting | til that the weather forecasting method "persistence," where one merely predicts that tomorrow's high-temperature (in this case) will be the same as today's, is quite successful with an average error of only 6 degrees. but this method (obviously) does not describe a probability distribution of possible temperatures and... | challenge forecast contest, url, persis ====== you can go [here](_url_0_) and look at how persistence (persis) fares against real forecasters in the annual weather challenge forecast contest. it's pretty terrible. | 2 | [] | [] | [
"http://wxchallenge.com/challenge/results.php"
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call to all entomologists: need help identifying this bug! | hey guys, i woke up last night to some bites on my face and i suspect it is once again some bedbugs (disappear for months here and then reappear). however, whenever the bedbug emerge, i find quite a lot of these guys _url_0_ lying around dead (from poison) or crawling, but never or very rarely do i find a bed bug. what... | gibbium aequinoctiale, spider beetle, anobiidae ====== it's a spider beetle (anobiidae: ptininae), probably [*gibbium aequinoctiale*](_url_0_). they definitely don't bite and have no association with bedbugs; if you're finding them in large numbers, you may have some infested food in your house. | 7 | [] | [
"http://i.imgur.com/R1yFx.jpg"
] | [
"http://bugguide.net/node/view/55820"
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way to measure absorbancy and hydrophobia? | is there a way to measure absorbancy? and hydrophobia? a diy home method? | water, absorbancy, water absorbed ====== i'm not sure what you mean by absorbancy. do you mean the amount of water absorbed? this could be done simply by weighing the material dry versus wet. hydrophobicity......im not too sure about. in lab, we can do water contact angles. this is where a drop of water is deposited an... | 3 | [] | [] | [] | [
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my gf had two patients at hospital where she works with the same date of birth as her today. i tried to explain that this probably wasnt as unlikely as it sounded but i lack the mathematical skill to work out out the probability. could someone show me how? | date of birth, birth, probability ====== **edit**: there was a mistake in my original calculation, as pointed out by rs14-2. see edit at the bottom for correction. are you thinking of [the birthday problem](_url_0_)? that's for any two people out of a group having the same birthday just in terms of day of the year, if ... | 8 | [] | [] | [
"http://en.wikipedia.org/wiki/Birthday_problem",
"https://www.google.com/search?rlz=1C1CHFX_enUS447US447&aq=f&sugexp=chrome,mod=14&sourceid=chrome&ie=UTF-8&q=365*95#hl=en&rlz=1C1CHFX_enUS447US447&sclient=psy-ab&q=1+-+((34674%2F34675\\)%5E100+%2B+(34674%2F34675\\)%5E99*(1%2F34675\\)... | [
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i've started studying quantum physics but have come across a problem i simply can't get my head around... | from my understanding, in beta decay, a down quark in the neutron emits a w- boson, which then decays into a b- particle and an electron antineutrino, and then changes into an up quark. i know that a down quark weighs more than an up quark, but a w- boson weighs much more than the difference between them so where is th... | good questions, decay, energy ====== these are two very good questions. starting with the b- decay: the issue here is that the w- that decays is actually not a real particle, but a virtual particle. a virtual w- does not necessarily have the same mass as a real w- boson, and exists solely to transmit the weak force. wh... | 11 | [] | [] | [] | [
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why do some ekg readings require only three leads while others require 12 leads? | obviously it's to be more specific but what exactly are they doing with more leads? | measure the potential, potential difference, extra leads measure ====== the extra leads measure the potential difference in different directions. effectively, they "look at" the heart from different directions. for instance, leads v5 and v6 are place low and far to the left on the chest. if you're having an infarction ... | 6 | [] | [] | [] | [
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why do ekgs require 12 leads, and why are they placed where they are? | pretty much what the question said. why do ekgs use 12 leads instead of any other number, and what's the significance of their placement, including the ones on the arms and legs? | leads, heart, left ====== to start: 12-lead ekg refers to the number of views the 10 electrodes on the skin take. the four limb electrodes have six different views that they can see. you're able to draw a line through each electrode to "see" what parts of the heart are damaged or whatever else you're looking for. here'... | 46 | [] | [] | [
"https://s-media-cache-ak0.pinimg.com/564x/69/b1/4e/69b14e6b020a3f52861369dc51fbe19c.jpg",
"http://www.emtresource.com/wp-content/uploads/2014/04/12-lead-ecg-placement.png",
"http://www.jchimp.net/index.php/jchimp/article/viewFile/14383/html/60429",
"http://ecg.utah.edu/lesson/1"
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is pkw at 25°c exactly 14? | is it exactly 14 due to coincidence or is it something we have rounded for ease of calculations? | ease of calculations, rounded for ease, mpa ====== we have rounded for ease of calculations. the pkw of water is also affected by pressure. normally, pressure is 1 atmosphere, which is equal to about .1013 mega pascals (mpa). pascals are the standard unit of pressure, and we multiply them by one million (hence mega) to... | 2 | [] | [] | [
"http://www.nist.gov/data/PDFfiles/jpcrd696.pdf"
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can an arthropod's exoskeleton repair itself the same (or in a similar) way as a human's endoskeleton? | living tissue, lice combs work, tissue ====== yes, *if* it's over living tissue. but it's not like human skin where it quickly patches itself, any significant damage to an exoskeleton basically means mr. bug is going to bleed to death. that's basically half of how lice combs work - they strip the eggs from hair shafts,... | 4 | [] | [] | [] | [
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what is the physical setup used for the production of thermal neutrons used to create the 'rio red' grapefruit strain? | i was reading about [red grapefruit and how they were created through radiation mutagenesis](_url_2_). in particularly the [rio red](_url_0_) commonly used is cited as having been the product of thermal neutron irradiation of plant tissues in the 1980s in rio (the city). none of the biology articles talk about the phys... | simplest option, agree, reactors or accelerators ====== i agree with you. if there are no reactors or accelerators available, a pube or ambe source with a moderator seems like the simplest option. | 7 | [] | [
"https://mvd.iaea.org/#!Variety/282",
"https://en.wikipedia.org/wiki/Neutron_source#Radioisotopes_which_decay_with_alpha_particles_packed_in_a_low-Z_elemental_matrix",
"https://en.wikipedia.org/wiki/Grapefruit#Ruby_Red"
] | [
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1209649/pdf/240.pdf"
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does a feynman diagram exist for wheeler's delayed choice experiment? | i have been looking online for a feynman diagram for either wheeler's delayed choice, or quantum eraser and can't find them. i am not entirely sure it is possible to describe this interaction using a feynman diagram, but i thought i would ask before giving up. if a diagram exists i would like to know what it looks like... | feynman diagrams, quantum field theory, quantum mechanics ====== feynman diagrams are not typically used in quantum mechanics, but in quantum field theory. you *can* do it, but there are a couple of caveats: 1. no quantum process is determined by one feynman diagram. several of them contribute, the same way that multip... | 4 | [] | [] | [
"http://arxiv.org/abs/hep-th/0605061"
] | [
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what is the probability that a randomly vibrating point source vibrates in a given (3d) direction? | i was thinking today about the likelihood of someone spontaneously exploding, where since every atom is vibrating randomly they all moved in opposite directions at once. this made me think, "well, whats the probability that an atom moves in a given direction". if it was a discrete set of directions this would be trivia... | point vibrating, random direction, point ====== the probability of a point vibrating along some random direction is 0. it's possible for a point to vibrate in a given direction, but it almost never happens. | 9 | [] | [] | [] | [
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is 3-d printing structurally sound method of building? | i just saw the video of the ["3-d printed mini 787 engine with working reverse thrust"](_url_0_) and couldn't help notice building layers on every part of the engine. is this a sound method to really build "any" thing? (not engines but other common household items lets say). | kind of tolerances, kind of stresses, manufactured parts ====== that depends on what kind of tolerances your application has and to what kind of stresses you expect to expose the manufactured parts. the technologies typically used in consumer-grade 3d printers (fused filament fabrication or fused deposition modeling) h... | 2 | [] | [
"https://www.reddit.com/r/videos/comments/3ivsgm/3d_printed_mini_787_engine_with_working_reverse/"
] | [
"https://othermachine.co/blog/video-tiny-aluminum-turbine-cut-on-othermill/",
"http://www.gizmag.com/ge-fires-up-all-3d-printed-jet-einge/37448/"
] | [
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where/how does shape-memory metal stores information about it previous state? | crystal, plastic deformation, plastic ====== in some sense, they store that information in their current configuration. shape-memory is a fascinating property, but to understand what's going on you need to know about how plastic deformation usually occurs in metals. ok: in metals, plastic (permanent) deformation occurs... | 5 | [] | [] | [] | [
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what does sine sound like? | more specifically, perfect sine is the wave length that "starts at 0, heads up to 1 by π/2 radians (90°) and then heads down to -1". what would that sound like? are there different "notes" that hit that frequency? | mathematical sine wave, time axis, match any mono-frequency ====== a mathematical sine wave does not have a pressure or a time axis associated to it so by choosing the right substitutes for x (e.g. p/p0) and y (e.g. 2pi*t/t) you can match any mono-frequency sound to the sine function. in nature you will hear either "si... | 3 | [] | [] | [] | [
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what would the magnetic field of a knitted fabric look like? | [removed] | coolest question, magnetic fields, current ====== so this is, without a doubt, the coolest question that i've seen in a while. consider reposting this to /r/physics too, they love neat problems like this. in the 'far field' limit, where you are far sufficiently far enough away, many of these magnetic fields will cancel... | 2 | [] | [] | [] | [
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if scientists found an undiscovered ancient animal with severe deformities, how would they be able to tell that a feature is a deformity or a naturally occurring attribute? | deformity, symmetrical, wonderful fractal maths ====== i can't tell you for all deformities, but i can tell you about most deformities. virtually all life is symmetrical in some way. from simple cells, to the wonderful fractal maths of the way plants lay out leaves, petals etc. all chordate animals are bilaterally symm... | 3 | [] | [] | [] | [
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what happens to the body when your cortisol levels are constantly too high? | broad question, human body, cortisol ====== this is a really broad question, since excessive cortisol in the human body can have a lot of implications. i'll just talk about one of them. one area of your brain that has a lot of cortisol receptors is the hippocampus. there is some evidence that excess cortisol can cause ... | 10 | [] | [] | [
"https://en.wikipedia.org/wiki/Cushing%27s_disease",
"https://www.ncbi.nlm.nih.gov/pubmed/20829623"
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how are scientists able to add plasmids into cells? | i was watching a lecture online about how now scientists are able to add plasmid with dna into cells in order to gain a new gene expression. but they never explained how they added the plasmid and now i am extremely curious! | bacteria floating, heat shock, basically a liquid ====== to insert plasmids into bacterial cells you usually add a concentration of plasmids to a bacterial culture (basically a liquid solution with plasmids and bacteria floating around) and heat shock the bacteria. the heat shock allows the plasmid to transverse across... | 3 | [] | [] | [
"http://labs.mmg.pitt.edu/gjoerup/Fugene6.pdf",
"http://en.wikipedia.org/wiki/Lipofectamine",
"http://en.wikipedia.org/wiki/Electroporation",
"http://en.wikipedia.org/wiki/Natural_competence#Mechanisms_of_DNA_uptake"
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how tightly can we compress matter with our current technology? | how much mass can we pack into a centimeter? | lithium deutride ceramic, deutride ceramic fusion, ceramic fusion fuel ====== if you want the most extreme, i was told that in the core of a thermonuclear device at detonation, the lithium deutride ceramic fusion fuel is compressed to ~1000x solid density. but this is using explosion derived xrays from a fission device... | 8 | [] | [] | [] | [
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how do electromagnetic generators work? | there seem to be too many videos showing magnetism used to generate/help generate electricity to dismiss: [one](_url_0_), [two](_url_2_), and [three](_url_1_), but it all seems too good to be true and you know what they say about that! | normal power generator, normal power, power generator ====== well a normal power generator has a steam or water turn a magnet, be it hard or an electromagnet. as the magnet turns it generates a time changing magnetic field. looking at one of maxwells equations, faradays laws, you see that the curl of the electric field... | 4 | [] | [
"https://www.youtube.com/watch?v=Wk4m1MLZudE",
"https://www.youtube.com/watch?v=CfWwPN-mTBQ",
"http://www.youtube.com/watch?v=uTtq3ALAtDE"
] | [
"http://en.wikipedia.org/wiki/Maxwell's_equations#Amp.C3.A8re.27s_law_with_Maxwell.27s_correction",
"http://peswiki.com/index.php/Directory:Magniwork#Affiliate_Sites"
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does the hall effect occur without an external magnetic field? | when a current is exposed to a magnetic field, the field interacts with the moving electrons to produce a force called the lorentz force. the electrons then are pushed by the lorentz force to one side of the wire. this magnetic field is usually described as something provided by an external source. however, any moving ... | great question, wire, magnetic field ====== this is a great question. let's consider a cylindrical wire with a dc current uniformly distributed through any cross section. (this is what generally happens for dc current.) this will generate a circumferential magnetic field inside the wire, as is easily seen via ampere's ... | 5 | [] | [] | [
"http://en.wikipedia.org/wiki/Topological_insulator"
] | [
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does your skin grow a tolerance, and eventually rely on products like proactiv? | it seems like, from personal experience and hearing from friend testimonials, that people on the treatment sometimes get even worse skin than what they started out with after stopping use of proactiv, not providing any real long-term benefits. i'm thinking the product changes the skin's behavior and natural production ... | benzoyl peroxide, main being benzoyl, bpo ====== proactiv is - as far as i can tell, a combination of several chemicals mainly used to treat acne, the main being benzoyl peroxide (bpo) as well as some moisturisers, exfoliants etc. a quick note on acne itself - generally thought to be caused by blockage of follicular op... | 12 | [] | [] | [] | [
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in the dropped slinky experiment, would the hovering depend on the length of the extended slinky? | sorry about the terrible title, i couldn't think of a better one. i'm referring to this [experiment](_url_0_), which completely blew my mind when i first saw it. the bottom of the slinky clearly 'hovers' until the slinky is totally compressed, then the slinky as a whole falls down to the earth. what if this experiment ... | fast perturbations travel, hovers depends, slinky ====== how long it hovers depends on the length of the slinky yes, but also on how fast perturbations travel through the slinky. if you essentially tied three slinkies together, it would take longer for the bottom to move, but not three times as long; it would be less t... | 3 | [] | [
"https://www.youtube.com/watch?v=eCMmmEEyOO0"
] | [
"https://www.youtube.com/watch?v=JsytnJ_pSf8"
] | [
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is there any scientific/non-pseudoscience (e.g. not esp) explaination for feeling like you're being watched? | i'm talking about the sensation i sometimes experience - and assume others do to, since i've seen it referenced in films and such - where i'll feel like someone is watching me, turn around, and notice that someone is. is this purely coincidence? picking up on subtle social cues of people around you who've noticed you'r... | coincidence and placebo, placebo effects, coincidence ====== coincidence and placebo effects seem like likely explanations. the act of turning around may well get someone's attention and cause them too look at you - they may have been looking elsewhere. you might 'feel' someone's presence from sounds and other small cu... | 6 | [] | [] | [] | [
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what is happening when something becomes "second nature" or habit to us, such as tying our shoes? does it move to a different part of our brain? | i'm referring to when people seem to do things automatically after many years of learning them. example: when we first learn to drive, we concentrate all our brainpower on doing everything correctly. a few years later we barely have to think about pressing the gas, brake, steering, etc. does this information move to th... | describing the formation, corticocortical connections, hippocampus ====== i think you're describing the formation of corticocortical connections. when you're first learning something consciously, you rely heavily on a part of your brain called the hippocampus to coordinate activity between the neurons required for the ... | 2 | [] | [] | [
"http://faculty.washington.edu/chudler/java/ready.html",
"http://en.wikipedia.org/wiki/Cerebellum#Learning"
] | [
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is the resultant force of a load the area under it? | say you have a tilted beam (homogenous distribution of mass) under the influence of gravity. the load would form a parallelogram (if you drew the vectors) but the resultant would be one vector times the actual length, which wouldn't be equal to the area of said parallelogram. i guess this has to do with the vectors, bu... | post a diagram, possibly post, diagram ====== could you possibly post a diagram? things like this are easier to solve if they can be visualized and it's hard to tell what exactly you mean. | 3 | [] | [
"http://i.imgur.com/fcuvaXd.jpg?1",
"http://i.imgur.com/OIfZTVJ.jpg?1"
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universal drift / absolute reference point | just a question that bothers me: my relative movement is 0... but earth is spinning around the sun, the sun is moving towards the galactic center and the milky way is drifting through space. how fast am i actually moving? is there any way to calculate an absolute universal movement? would it be possible to measure a do... | relevant in reference, point, velocity ====== velocity is only relevant in reference to another object/point. relative to what? also, some comments for a [question](_url_0_) asked earlier today may be of some relevance. | 4 | [] | [] | [
"http://www.reddit.com/r/askscience/comments/lslea/how_to_measure_speed_in_space/"
] | [
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how much g's on the event horizon? | how much gravitational acceleration is there right on the event horizon of a black hole? is it dependent of the size of the black hole? and lets say that you are in a ship that is accelerating at that value, what would you expect to happen to light and an observer in that ship.(before getting close to the light speed) | black hole, proper acceleration, black ====== in gr, you have an immense freedom to choose your coordinate system and many quantities and physical phenomenon are described described differently depending on your coordinate system. for instance, suppose you are an observer far away from the black hole and are using so-c... | 6 | [] | [] | [
"https://en.wikipedia.org/wiki/Spaghettification"
] | [
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what are the differences between daily and monthly wear contacts from a materials and durability standpoint. | soft contact lenses, hydrogel, discussing soft contact ====== without getting into too much detail because there are so many different materials, when discussing soft contact lenses there are two categories of materials: hydrogel and silicon hydrogel. hydrogel materials were the first soft contact lenses. to generalize... | 22 | [] | [] | [] | [
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what is going on when we are so afraid we "shit ourselves?" | back to primate, primate stage, tie ====== may tie all the way back to primate stage or before. many animals will void their bowels as a defense. it can be a deterrent to predators. in reptiles it is less of a deterrent than perhaps a method of unburdening the body of weight and freeing up energy. most reptiles vomit t... | 2 | [] | [] | [] | [
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how does mobile internet (carrier internet) work? how does it get to the reciever intact? | i was wondering this when i was travelling by bus and browsing reddit. how does it account for my movement, for disturbances, for other people using it? | ball, throw, phone ====== all right, i'll give this one a shot. say you capture your data (words, text, pictures, whatever) in a tennis ball and throw it to your friend across the street. he catches it and throws back his responses. now suppose you both have an unlimited number of balls you can package your stuff into ... | 5 | [] | [] | [] | [
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is there an easy test to see if a prediction vs time is self consistent? | nate silver at 538 has made a name for himself predicting presidential races. this year, his model seems to give a surprising amount of volatility. i'm specifically thinking of of his polls only prediction, which has gone from as high as ~90% for clinton and as low as ~50%. i feel like there should be some way to test ... | model, test, error ====== i split this post into two sections: testing models and why 538's predictions are so volatile. --------------------------------------- testing probabilistic models: there are a number of ways to test model correctness, though models are easiest to test against the data they are intended to pre... | 9 | [] | [] | [
"https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=number%20of%20votes%20cast%20in%202012%20presidential%20election",
"https://en.wikipedia.org/wiki/Binomial_distribution",
"https://en.wikipedia.org/wiki/Normal_distribution#Standard_deviation_and_tolerance_intervals",
"h... | [
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have we come any closer to understanding the mind/body problem? | clarify which part, mind-body problem, referring to. working ====== you should clarify which part of the mind-body problem you are referring to. working theory is that the mind is a phenomenon that arises from processes in the brain. there are numerous brain damage cases that illustrate this effect. when the brain is d... | 3 | [] | [] | [] | [
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how many holes in pants? (not really math, but not really any one thing, so...) | so, i've had this question that's been nagging me. do pants have 1, 2, or 3 holes? they have 3 openings, but they all link to each other. and from one position it looks like 2 holes coming together to make one, but from another, it looks like one hole that splits off into two. in a way, it can also be seen as one conti... | ignoring pockets, pockets and zippers, topologically pants ====== i think topologically pants (ignoring pockets and zippers) are a genus 2 surface, meaning they have 2 holes. [this](_url_0_) is a very simple example of a genus 2 surface. take that shape, stretch the top of the perimeter upwards without the center conne... | 16 | [] | [] | [
"https://upload.wikimedia.org/wikipedia/commons/b/bc/Double_torus_illustration.png",
"https://en.wikipedia.org/wiki/Pair_of_pants_(mathematics)"
] | [
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what could cause such an artifact on google maps? | [google maps link](_url_0_) | solar reflection, mirrored surface, pure white form ====== a "solar reflection off a mirrored surface", as mentioned in another post, seems the most likely case. the pure white form is typical of an overexposure as received by a digital camera. the odd shape could be due to imperfections in the shape of the mirror that... | 14 | [] | [
"http://maps.google.com/maps?q=50.403871,+30.392521&num=1&t=h&vpsrc=6&ie=UTF8&ll=50.40391,30.392274&spn=0.001489,0.004128&z=19&iwloc=A"
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qft electromagnetic field vs. luminiferous aether? | what are the differences between quantum field theory's electromagnetic field and the dismissed 19th century idea of the luminiferous aether? | quantum electrodynamics obeys, electrodynamics obeys lorentz, air makes sound ====== well they're not really at all similar except that they are both related to the propagation of light. quantum electrodynamics obeys lorentz symmetry meaning that light propagates at the same speed regardless of inertial reference frame... | 3 | [] | [] | [] | [
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bit of a technical question: what would be the consequences of determining the cardiac axis using leads i and ii of a bipolar ecg as opposed to leads i and iii? | title says it all. cheers! | axis, avf, negative ====== actually, i use leads i and avf. there is a more complicated way, but this is how we typically do it in the hospital. create an xy axis. the left side of x is 0 degrees, and down y is 90 degrees. lead one is a vector towards 0 degrees and avf is a vector towards 90. a normal left axis falls b... | 3 | [] | [] | [
"http://upload.wikimedia.org/wikipedia/commons/thumb/5/56/Hexaxial_reference_system.svg/325px-Hexaxial_reference_system.svg.png"
] | [
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how often is it important to understand something on the molecular/atomic level? | it seems that once or twice a week, someone asks a question about what's happening at the atomic or molecular level of x. i'm always interested in the answers, but it got me wondering. how frequently do scientists wonder the same thing? are there particular fields in which it is always important to understand what's ha... | waking minute, minute, chemist ====== i think about it every waking minute, but that's because i'm a chemist. basically, if you understand how a particular chemical reaction occurs, you can tweak it to make something else or make it more efficient or faster. particle physicists work at this level, too. biologists will ... | 8 | [] | [] | [] | [
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what's the right way to think about r vs r^2? | say 2 variables have a correlation of 0.6. i look at that and think "wow, 60% of variable a is explained by b." that seems like a lot. but the r^2 would be only 0.36, which seems less impressive. what's the right way to intuitively think about correlation vs variance determination? when is one more useful than the othe... | null hypothesis, fraction of variance, forming a t-statistic ====== r^2 (not r) is actually the fraction of variance in y that is explained by x. it is also important to know the significance of the correlation, that is done by forming a t-statistic from the r value, and testing it against the null hypothesis. these da... | 9 | [] | [] | [
"http://vassarstats.net/rsig.html"
] | [
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would an electric shock from a source of 10a with 1000v, feel the same as a shock from 1000a with 10v? | does the shock intensity depend on power (vxa) or does voltage or current play a larger part? thanks | current, source can provide, flows depends ====== for shocks, the current that flows depends not on how much current the source can provide but on the resistance. if your hands are dry and calloused, the resistance is around 100k ohms, so the current that flows at 10 volts is going to be low; by ohms law we can calcula... | 9 | [] | [] | [
"http://www.eplasty.com/index.php?option=com_content&id=345&catid=170:volume-09-eplasty-2009"
] | [
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when did 2013 really begin? | days are measured by the rotation of the earth on its axis, but years are measured by the orbit of the earth around the sun. i would guess 00:00 at either the prime meridian or the international date line if our system of measuring time was 100% accurate, but if it was perfect then we wouldn't need a leap year, right? ... | orbit, time, earth ====== not exactly. more like we picked fixed values for the length of days and years which are related to, but not the same as, rotation and the orbit of our planet. this is why we need leap seconds and leap years so that our simple cultural time systems stay matched up to the seasons and time of da... | 2 | [] | [] | [] | [
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why aren't r-squared values commonly used in some fields of research? | [removed] | url, post, questions ====== hi madelainew thank you for submitting to /r/askscience. **if your post is not flaired it will not be reviewed.** please add flair to your post. your post will be removed permanently if flair is not added within one hour. you can flair this post by replying to this message with your flair ch... | 2 | [] | [] | [
"https://www.reddit.com/r/askscience/wiki/faq",
"https://www.reddit.com/r/askscience/search?q=Why%20aren%27t%20R-squared%20values%20commonly%20used%20in%20some%20fields%20of%20research%3F",
"https://www.reddit.com/r/askscience/wiki/quickstart/askingquestions",
"http://redd.it/s4chc",
"https://www.reddit.com... | [
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why are the roofs of mouths ribbed? | i've noticed my cat and my friend's dog have ribbed mouth, and humans do as well, why? | hard palate, rugae, hard ====== hi. this is your hard palate. its ridges, known as rugae, aid in the physical breakdown of food during mastication (chewing). your stomach has rugae that also aid in physical digestion of food. according to [wikipedia](_url_0_), the hard palate is also important in speech and nursing. (t... | 3 | [] | [] | [
"http://en.wikipedia.org/wiki/Hard_palate"
] | [
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question about tension | you tie a rope to a tree and pull with 5 n force and the tension in the rope is 5 n. ok. you are in a tug of war and each side pulls with a force of 5 n and the tension in the rope is still 5 n. weird, but ok. but what if you are in a tug of war and one side pulls with 5 n and the other with 4 n? i would assume there w... | force, side pulls, tug of war ====== if you tie a rope to a tree, and pull with a force of 5n, the tree feels the force of 5n, and resists with an equal 5n force. if the tree is small, you'd see it deflecting to use the elasticity of the trunk to help generate that force (ie, acting like a spring) if you have a tug of ... | 10 | [] | [] | [] | [
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if you dropped a flea or tick from the empire state building, would it die on impact? or no because of it's respective body mass and size? | terminal velocity depending, mass ratio, velocity depending ====== for any object, you have a terminal velocity depending, to a first approximation, on it's surface area/mass ratio. in general, this will be smaller for smaller objects and so it's more likely that they will survive. [this](_url_0_) study from nature in ... | 12 | [] | [] | [
"https://scholar.google.co.uk/scholar?cluster=5094783782928677703&hl=en&as_sdt=0,5"
] | [
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why can't we use superfluidity to make perpetuum mobile? | why wouldn't this work? [example](_url_0_) | interesting question, working heat engine, heat ====== well, this is an interesting question. what you have posted is *not* a perpetual motion machine, but is very close to a working heat engine. heat is the ultimate source of energy that drives the capillary flow of the superfluid helium up the walls. effectively the ... | 3 | [] | [
"http://i.imgur.com/xWw9g.png"
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are there any situations or perspectives where "which of two events came first" is uncertain? | assuming both events are documented properly. | reference frame, frame, reference ====== absolutely! in special relativity, the order in which events occur can depend on your reference frame. say for example that i'm stationary relative to two alarm clocks that are an equal distance away from me. they go off at the same time from my perspective and the light that sh... | 16 | [] | [] | [
"http://en.wikipedia.org/wiki/Relativity_of_simultaneity"
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how do strong forces pull things from far away? | i heard that strong forces pull things stronger from farther away, and that these forces are so strong that nuclear forces are basically the residual spill-off from them. how is it possible that something can get stronger from farther away? wouldn't that pull everything into a certain range? | color confinement, effect you referring, quarks ====== the effect you're referring to is known as [color confinement](_url_0_). the force felt doesn't increase with distance, but it is approximately constant. however, this occurs in bound groups of quarks (either a quark and antiquark pair, which is a meson, or three q... | 7 | [] | [] | [
"http://en.wikipedia.org/wiki/Color_confinement",
"http://en.wikipedia.org/wiki/Quantum_chromodynamics",
"http://en.wikipedia.org/wiki/Quark",
"http://en.wikipedia.org/wiki/Asymptotic_freedom",
"http://en.wikipedia.org/wiki/Lepton"
] | [
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given that cerebrospinal fluid flows around the structures of the brain, would messenger chemicals from synaptic activity in one area be passed to, and alter synaptic activity in other regions of the brain? | messenger chemicals, chemicals i assuming, assuming you referring ====== by messenger chemicals i'm assuming you're referring to hormones. neurotransmitters travel across synapses so the answer is no. the hormones that are secreted by the brain (hypothalamus-pituitary) get dumped into systemic circulation and thus woul... | 5 | [] | [] | [] | [
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at what point in your academic career are you a scientist? | i'm a lowly undergrad, the most i can do at my level is maybe a 3rd/4th year project or work as a lab/research assistant, i'm not a scientist. what about graduate students, i know they have original research going on but does that make them a scientist? do you call yourself a scientist when you're a tenured professor o... | neil degrass tyson, neil degrass, seeking out knowledge ====== neil degrass tyson would probably say that your a scientist as soon as your born and you only stop being one when you stop seeking out knowledge. | 11 | [] | [] | [] | [
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what is the equation describing an electrostatic interaction through a varying dielectric medium? | point charges matter, dielectric materials alter, materials alter ====== dielectric materials alter the electric field, so all of the material between the point charges matter. define the dielectric constant as a function on x, where x is the axis on which i and j lie. e(p) = 322.0637 * qiqj / ∫(e(x)dx) for x from xi t... | 2 | [] | [] | [] | [
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how do we have control over our movement? | i understand how we move, with joints, muscles, nervous system etc... though i am baffled as to how we have control over our movement. since we don't think, "brain, move my right arm, please", how do we decide to move in the way we want to? it has been confusing me recently as to what i do to move my body. so confusing... | sense, brain, symbolic map ====== it's the subconscious part of the brain. as a rule we're aware of only a small part of what our brain does. you're basically talking about volitional movement, which is intimately tied up to some of the biggest mysteries of the brain, things like will, consciousness, self-awareness. a ... | 10 | [] | [] | [
"http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1950571/",
"http://www.ini.uzh.ch/~conradt/Projects/PencilBalancer/",
"https://www.youtube.com/watch?v=f9UngTdngY4",
"https://www.youtube.com/watch?v=w2itwFJCgFQ"
] | [
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in the periodic table, why does the d block start with 3d, rather than 4d? | why does period 4 have 4s, then 3d? shouldn't it be 4d? | lower energy, shell, lower ====== the 4s shell is actually lower energy than 3d. this means the 4s shell fills first before 3d. if you look at period 3, you’ll see that the 3d isn’t filled in that period. here is a diagram of the electron shell energies which determines fill order. _url_0_ | 26 | [] | [] | [
"https://chemistry11mrstandring.wikispaces.com/file/view/level.gif/147227731/level.gif"
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is there any rhyme or reason to the charges of polyatomic ions, or is it completely random? | the charges never seem to line up with the elements that each polyatomic ion contains. (ex. nitrate's charge is -1, but contains 4 negatively charged atoms, so shouldn't the charge be at least -4? peroxide's charge is -2, but contains 2 oxygen, so shouldn't the charge be -4?) | electrons, polyatomic ions, atomic ion counterparts ====== it's wrong to think about polyatomic ions as a bundle of atomic ions. they are really molecules, containing covalent bonds, which just like their atomic ion counterparts still need to gain or lose electrons to complete their orbitals. however, those covalent bo... | 5 | [] | [] | [
"https://en.wikipedia.org/wiki/Peroxide",
"https://en.wikipedia.org/wiki/Nitrate"
] | [
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what determines the rate of action potential propagation? | i'm going to ask what i think is the same question three times in three different ways because i can't quite pin down what i'm trying to say. hopefully it makes sense... assuming no myelination, what is actually responsible for mediating the change in charge along an axon during an ap? it's not the diffusion of na+, is... | covered regions, successive ion channels, open successive ion ====== the na+ is diffusing down the covered regions of the axon. time is saved by not having to open successive ion channels. the signal propagation velocity is limited by the diffusion rate of na+. | 2 | [] | [] | [] | [
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i'm french, my book talks about a "fonction sinusoïdale". it may to do something with sine, but i have no further clue. what is it ? | my books says that fourier found that a periodic function, especially sound waves, is always the sum of "fonctions sinusoïdales". i'm french and i haven't found a translation, as i can't find what a "fonction sinusoïdale" is : i know about the sine function ("fonction sinus" in french), but is it the same ? is a "fonct... | sine function, slightly more generic, generic form ====== a sinusoidal function is just a slightly more generic form of the sine function. if f(x)=sin(x), then f(x) is the sine function but if f(x)=asin(x-b), then technically f(x) is not a sine function, but it is a *sinusoidal* function. at high school you can probabl... | 23 | [] | [] | [] | [
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prolonged exposure to high pressure | what would be the effects on a human body from prolonged exposure to high pressure (400-500 kpa approx 100ft underwater 30m). on the scale of days and weeks at this pressure. the idea is what would happen with a pressure equalized submarine and why don't we pressurize them. | bbc documentary, spend days, lives of saturation ====== [this bbc documentary](_url_0_) follows the lives of saturation divers who spend days/weeks at pressure even higher than you specified. there do not seem to be any acute effects of high pressure except very high voices from the helium required in the breathing gas... | 9 | [] | [] | [
"http://www.youtube.com/watch?v=B3BWSMrgi3I"
] | [
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"water" on the road | when i'm out driving i often see these things that look like water puddels in the distance. but as i get closer, they disappear. can someone please tell me why we see these things, and how they are "created"? | decent diagram, sky, shimmering blue sky ====== it's called an inferior mirage; [here's a rather decent diagram with example picture](_url_0_). light coming down from the sky hits the density gradient near the road and gets bent back upward toward your eye over on the right side, but since that light came from the sky ... | 2 | [] | [] | [
"http://www.animations.physics.unsw.edu.au/light/geometrical-optics/images/mirage_truck.jpg",
"http://4.bp.blogspot.com/_PaqGry0Ohzk/TJ7jpFpJj7I/AAAAAAAAAOU/6FTNyoaHp4A/s1600/2688993540012523983hPDjyG_ph.jpg"
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what are some common causes of static electricity outside of the widely known factors (i.e., wool sweaters, etc) | electrons, electricity is caused, materials ====== static electricity is caused by a charge imbalance between two materials. most things are electrically neutral in a normal state, but when certain materials come in contact with each other electrons from one can be transferred to another. the material with extra electr... | 2 | [] | [] | [
"http://www.static-sol.com/articles/static_build_up_on_people.htm"
] | [
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do physical forces have a reference frame? | so i watched interstellar last night and it got me to thinking about spaceships and relativity. we are used to seeing science fiction craft that spin in order to create the illusion of gravity due to centripetal force. in some of those depictions, the spinning disk is separate from the hub; that is, the hub can remain ... | inertial reference frame, reference frame, inertial ====== inertial reference frames are, by definition, inertial. rotation is a kind of acceleration (remember that velocity is linear), therefore a rotating system is not in an inertial rest state, and so you can't consider a rotating system as an inertial reference fra... | 6 | [] | [] | [
"http://en.wikipedia.org/wiki/Absolute_rotation"
] | [
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what is the "purpose" of short-lived particles like the muon or tau? | or to put it another way, if these particles didn't exist, would there be any noticeable impact on reality? | chiral fermions coupled, standard model, chiral fermions ====== the standard model is a very delicate theory in that it contains objects (chiral fermions coupled to gauge fields) which are dangerously close to being nonsense. in particular, if a theory of this type almost always has something called a [gauge anomaly](_... | 6 | [] | [] | [
"https://en.wikipedia.org/wiki/Gauge_anomaly"
] | [
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are there any shapes that maintain a constant surface area while being consumed at a steady rate? | imagine setting a cube of sugar on fire. as the outside of the cube burns off, it's surface area decreases. conversely, i've heard that some clever taurus-based designs for gunpowder can yield increasing surface areas as they are burned, at least temporarily. is there any shape that yields a linear surface area graph w... | surface area, cool question, surface ====== cool question, the answer is yes! this can be achieved by nearly *any* shape, depending on the direction of the consumation, up to a certain point of course. once it's been consumed down to a small size it is rather more difficult to maintain a constant surface area. if you w... | 2 | [] | [] | [] | [
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how come you can remember that you had a good idea, some very particular details about it, but not the core idea itself? | memory, specific thing, relationships ====== rather than remembering a specific thing... we remember the relationships between things. we will recall something best when the set of relationships now are most similar to the set of relationships at the time the memory was laid down (you can remember more easily what you ... | 3 | [] | [] | [] | [
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how small can electromagnets be made? both what has been done and in theory as well... | i've searched everywhere for this answer. help! :) | magnetic field, flowing charge, charge will create ====== well, to be fair, any material containing a flowing charge will create a magnetic field. so hypothetically the smallest electromagnets we've made would be the tiny wires carrying information around the chips in electronic devices. | 4 | [] | [] | [
"http://en.wikipedia.org/wiki/4-Cyano-4%27-pentylbiphenyl",
"http://en.wikipedia.org/wiki/Lenz%27s_law",
"http://en.wikipedia.org/wiki/Aromaticity"
] | [
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does new evidence point to geocentrism? | so, this is going to be my first reddit post, and hopefully you guys and gals can help me out. the other day i heard a noise coming from my computer, it was the warning alert indicating that someone on the internet was wrong. i therefore engaged in a brief discussion with someone who advocates geocentrism. never having... | earth, universe, center ====== well, the earth most certainly is the center of the *known universe*. the inclusion of the word known is very important. the known universe is bounded by a sphere which is exactaly the age of the universe times the speed of light distance away. that is, as reported by the planck team rece... | 17 | [] | [
"http://en.wikipedia.org/wiki/Michelson-Morley_experiment",
"http://magisterialfundies.blogspot.com/2013/03/copernican-principle-1532-2013-rip-why.html",
"http://www.galileowaswrong.com/galileowaswrong/features/5.pdf",
"http://blogs.discovermagazine.com/badastronomy/2010/09/14/geocentrism-seriously/#.UUycXhxw... | [
"http://www.reddit.com/r/askscience/comments/1acd0i/has_the_copernican_principle_been_debunked/",
"http://en.wikipedia.org/wiki/Not_even_wrong"
] | [
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vision and brain researchers: looking to find the correct topical label for something i've notice about vision, so that i can look into it further. is there a static frame of reference? | hi there! i really hope that i can describe this accurately! my concern that i cannot (lacking good terms) is my justification for the lack of brevity. i've always been a big fan of stereogram puzzles, and this has induced a habit of playing with my subjective visual experience. things like the floating sausage finger ... | reference frames, egocentric and allocentric, geocentric ====== i'm not 100% sure i understand what you are getting at, but the terms you might be looking for are egocentric and allocentric (sometimes "geocentric", but less common) reference frames. typically they are used to refer to navigation and spatial positioning... | 2 | [] | [] | [
"http://www.nmr.mgh.harvard.edu/mkozhevnlab/?page_id=308"
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[optic] why does every measurement of a system that contains coupling/transmission is approximated through a lorentzian function? | i often read that something in the field of optic gets measured and then gets least-square fitted by a lorentzian functionl. i think it was always with coupling/transmission etc. hence the question, since i didn't find any source and everything that i found just stated that they did it. | bit in optics, oscillator, simple vibrating spring ====== the reason lorentzians pop up quite a bit in optics is that they describe the behavior of what is called a lorentz oscillator. the basic idea is that to a first approximation you can treat an electron-bound to a nucleus as a simple vibrating spring. when if you ... | 5 | [] | [] | [
"http://i.imgur.com/194KJcq.gif"
] | [
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what do the thick bars represent on atomic spectrum lines? | like [this](_url_0_) is it the brightness at one wavelength? or is it a continuous spectrum of wavelengths? or is it a bunch of smaller lines that are really close together? | dark lines represent, represent the wavelengths, wavelengths absorbed ====== in an absorption spectrum, the dark lines represent the wavelengths absorbed by matter in between the source and the observer. the spectrum emitted is potentially continuous and in many cases eg stars is approximated as a black body spectrum. ... | 5 | [] | [
"http://chemistry.bd.psu.edu/jircitano/V.gif"
] | [] | [
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why does an elephant's heart rate increase when it lies down? | _url_0_ > when standing, the elephant's heart beats approximately 30 times per minute. unlike many other animals, the heart rate speeds up by 8 to 10 beats per minute when the elephant is lying down. | tidal respiratory volume, increase heart rate, recumbent position reduces ====== from [this web page:](_url_1_) the reference for that second para is from [this citation.](_url_0_) in effect, the weight of the animal in the recumbent position reduces tidal respiratory volume; the compensatory mechanism is to increase h... | 47 | [] | [
"https://en.wikipedia.org/wiki/Elephant#Internal_and_sexual_organs"
] | [
"http://wildpro.twycrosszoo.org/s/00Ref/BooksContents/b453.htm",
"http://wildpro.twycrosszoo.org/s/0MProboscidae/Elephantidae/Loxodonta/Loxodonta_africana/10LoxAfrDetPhy.htm#Pulse"
] | [
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irisin hormone, why has a discovery this important gone by without hardly any mention? | sound earth-shattering, url, important discovery ====== _url_0_ this does not sound earth-shattering. what makes you think it's such an important discovery? also _it's_ is a contraction of _it is_. the possessive of _it_ is _its_. | 2 | [] | [] | [
"http://en.wikipedia.org/wiki/Irisin"
] | [
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scientifically, how is this basketball shot possible? | [this.](_url_0_) if it's true every action has an equal and opposite reaction, then how does the momentum of the ball not even cause a little bit of pushback, it just completely stops. physically, how is this possible? | essentially wedged, super slo-mo replay, ball ====== friction - it's essentially wedged in there. combine that with the fact that the ball has the ability to deform, so in a super slo-mo replay, you would see the ball change shape like [this tennis ball](_url_0_). this would never happen with a solid ball bearing, whic... | 3 | [] | [
"https://www.youtube.com/watch?v=Ea0tJhdNRxg"
] | [
"https://www.youtube.com/watch?v=VHV1YbeznCo"
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how long do landmines remain active? | how long does it take for the explosives to become inert? does the process by which the mines become unable to explode speed or slow depending on climate and soil composition? | common primer, wikipedia article, maintain its capacity ====== according to the wikipedia article for [anti-personnel mines](_url_0_) the most common primer/detonator charge used is an explosive called [rdx](_url_1_) which seems to be able to maintain its capacity to explode for a very long time (extremely stable). com... | 10 | [] | [] | [
"http://en.wikipedia.org/wiki/Anti-personnel_mine#Components",
"http://en.wikipedia.org/wiki/RDX"
] | [
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how did scientists (einstein?) know what would happen when an atom splits before it had ever been done? | produce smaller atoms, free neutrons, prior to actual ====== prior to actual experimentation, einstein couldn't elucidate exactly what it would look like when an atom was split, only that it would produce smaller atoms, free neutrons, and also an enormous release of energy, the sort of raw facts you get from the math i... | 3 | [] | [] | [] | [
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why does hypothyroidsm cause fatique? | how is the lack of thyroid hormons making you want to sleep? | regulating basal metabolism, play a role, role in regulating ====== thyroid hormones play a role in regulating basal metabolism. without those hormones the metabolic rate drops. as metabolism slows down so does the other chemical reactions (including in the brain) are reduced. severe hypothyroidism can actually cause c... | 7 | [] | [] | [] | [
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does a van de graaf generator make you positive or negative? | i'm really hoping for some sources here if possible. i've been taught using van de graaf generator that the belt is taking away electrons from the dome and whatever is in contact with the dome. which i thought would leave the dome positive and you positive, making hair repel from each other. recently some stuff i read ... | rub two dissimilar, pick, dissimilar materials ====== when you rub two dissimilar materials together, in some cases one material will pick up a positive charge and one will pick up a negative charge. what a van de graaf generator does is to transfer this charge, using a belt, to the metal dome. it is therefore possible... | 13 | [] | [] | [] | [
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why does capillary action not violate conservation of energy? | i know that energy is conserved, but in the case of capillary action, it seems as though it is creating gravitational potential energy without using any energy. how does this really work? | lowest energy state, fluid rise, energy state ====== it works because having the fluid rise up is the lowest energy state. the water molecules prefer to adhere to the walls of the tube and cohere to each other. that is, the formation of intermolecular bonds is energetically favourable, so much so that increasing gravit... | 14 | [] | [] | [
"http://science.jrank.org/pages/1182/Capillary-Action.html"
] | [
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assume i could travel 1000 years back in time...what foods/fruits i could ask for and not be surprised by it's appearance or taste? | i know that the definition of a strawberry has changed a lot over the past 100 years so, what can i expect of fruit and food if i were to go back earlier? | cultivated for thousands, fruit, thousands of years ====== not many fruit, only the stuff that's been cultivated for thousands of years... squash, melons, pomegranates, apples, peaches (the rest of the stone fruit), bananas... and i say this in generalities, but we have pretty much changed every fruit in the past 100 y... | 69 | [] | [] | [] | [
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do cities (or specifically the masses of the cites) produce any noticeable isostatic effects? | i imagine the mass of something like new york city is likely (?) comparable to a decently sized glacier covering the same area, and isostatic glacial rebound since the last glacial maximum is a very well accepted phenomenon. just something that occured to me after i took geomorphology... | nyc is waaaay, cubic feet, feet of water ====== nyc is waaaay less heavy than a glacier. i've got a lot of experience working with objects (aquariums) full of water, and i can tell you they are heaver than almost any equivalently-sized object that you might find in a city--to the extent that it's usually considered unw... | 7 | [] | [] | [] | [
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why does a plane look like its going up from the inside? | sorry if this is a stupid question but its hard to describe what i mean but i'm just curious why this is? surely if the plane is in the air and my position on the seat hasn't changed, then my view of the plane shouldn't change but from my position it will look as if the plane is rising vertically. | jumbo jets generally, jets generally fly, slight positive angle ====== jumbo jets generally fly with a slight positive angle of attack (slightly nose up). this helps generate lift at higher altitudes. so, you are seeing correctly, the front will look higher than the back. | 5 | [] | [] | [] | [
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a question about processor power.. | it seems like society acts as if we will continue to develop progressively more powerful computers forever, but is there a limit to how powerful we can make a computer? could a processor take too much energy to use or is there some sort of natural limit to the possible power of a processor? | power, processing power, computer ====== there are various limits to the potential computing power. the main one is the size of computer chips. a processor is just a huge number of transistors, on and off switches, which are used to process logic tasks. even those really old computers that took up whole rooms worked on... | 5 | [] | [] | [] | [
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can anyone please explain the difference between lumens and candela per square meter (cd/sqm) (in human language) as a measure of light brightness? | i am sourcing a product, a bicycle light. have 2 options. one option has higher lumens (cheaper) but the other has higher cd/sqm (more expensive). i am now having difficulty understanding the difference between lumens and candella per sqm. which one is a better indicator of light quality/intensity? | beam, lumens, light ====== a lumen gives the *total* amount of human-visible light given out. how bright the light actually is will depend on how wide the beam is. a very wide beam with a lot of lumens is as bright as a very narrow beam with a few lumens. a candela is maybe a more useful unit here. a candela tells you ... | 3 | [] | [] | [] | [
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watching the sun from outerspace. | well, in a lot of games you can watch the sun in outerspace. but i was wondering, can you watch the sun in outerspace without getting blind/eye damage? because if you look at the sun from earth your eyes will hurt a lot. edit: sorry for not setting the right category, i'm not sure where this belongs to. | sun, damage, depends ====== it depends on your distance from the sun. if you're in earth orbit, or closer to the sun than earth, yes, it will cause damage. farther from the sun, somewhere around jupiter, the intensity falls below the threshold for retinal damage. | 3 | [] | [] | [] | [
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what exactly is redox potential? | hi guys, i'm really trying to understand the role of redox potential in the functionality of cellular proteins. i don't think i ever got a good grasp of redox potential and what it exactly is. i understand that within the cell there are different compartments of varying redox potentials which can affect the functionali... | easier to understand, inorganic chemistry, electrons ====== you have the right idea - redox (reduction/oxidation) in inorganic chemistry is much easier to understand. oxidation is the process of losing electrons; reduction is the process of gaining electrons. there is a redox potential anytime you have two species with... | 4 | [] | [] | [
"http://en.wikipedia.org/wiki/Standard_electrode_potential_%28data_page%29"
] | [
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latest sixty symbols "currents and magnets". what is the 'lensing' effect along the wire? | in the latest [sixty symbols video](_url_0_) about current and magnets; every time the camera pans over the wire there is a [lensing effect](_url_1_) around it. it's hard to see in the picture, but the video is very obvious. i was thinking charged particles in the air, but this is happening even when (i think) there is... | heat, wire, instrument readings ====== it's heat! they're running 30v at 1.8a through that little wire, which is close to 60w (assuming it's all being dissipated in the wire, which is fairly safe to assume based on the instrument readings). | 5 | [] | [
"http://www.youtube.com/watch?v=UV0wtX9AXq4&list=UUvBqzzvUBLCs8Y7Axb-jZew&index=1&feature=plcp",
"http://imgur.com/3Ya7D"
] | [] | [
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do organic brains operate on any logic system? | by logic system, i mean that most modern computers use binary so everything can be broken into booleans/discrete voltages. other computers use hexadecimal/quantum, etc. do organic brains use any sort of system? | suuuuper complicated question, coding, place coding ====== suuuuper complicated question. shortest answer: brains use wildly different coding schemes to accomplish different tasks, but generally, the inputs and outputs of a neural system are represented by continuous variables, in the form of "firing rate," or how rapi... | 3 | [] | [] | [] | [
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in stoke's law (f = 6πηrv) where does the "6" come from? in simple terms. | i understand the other terms are to do with viscosity and a sphere, but i can't find any explanation of where "6" comes from. is it just because a sphere is used? or is there some complex mathematics behind it? | term gets integrated, giving a prefactor, ultimately gets multiplied ====== briefly, an 1/r^3 term gets integrated (giving a prefactor of 3/2) and ultimately gets multiplied by the surface area of a sphere, 4πr^(2). | 22 | [] | [] | [] | [
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when listening to large amateur orchestral groups (ex: "school chrismas pageant"), what happens in our brains when we single out individual dissonant players? | how do we single out which player in a tight group of 15 kids playing the same instrument is making that hackle-raising dissonance? specifically, from the perspective of somebody with no musical training whatsoever. is our directional hearing so good that we can pinpoint where the worst notes come from? or are we picki... | book chapter, sound, url ====== here's a [book chapter on auditory aesthetics](_url_1_) you might find interesting. i haven't read it fully, but there are several points in it that might address your question. for example, the authors describe a property of sound they call "roughness" that is present in cringe-inducing... | 2 | [] | [] | [
"http://en.wikipedia.org/wiki/Auditory_scene_analysis",
"http://mcdermottlab.mit.edu/bib2php/papers/McDermott_2011_Auditory_Preference_chapter.pdf",
"http://auditoryneuroscience.com/scene_analysis",
"http://en.wikipedia.org/wiki/Timbre"
] | [
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question about permittivity | hi, i am confused by the concept of relative permittivity at high frequency. after a whole day trying to figure how the permittivity is related to the conductivity of a material (a few books later i am now convinced some people fake understanding it or can't address it properly or i am stupid as stupid gets..which is p... | properties of metals, drude model, model for determining ====== you might want to look into the drude model for determining the dielectric properties of metals. the [first result](_url_0_) from a google search looks pretty good. | 2 | [] | [
"http://www.ioffe.ru/SVA/NSM/Semicond/Si/Figs/141.gif",
"http://en.wikipedia.org/wiki/Lossy_medium#Lossy_medium",
"http://www.nist.gov/data/PDFfiles/jpcrd162.pdf"
] | [
"http://optics.hanyang.ac.kr/~shsong/27-Metals.pdf"
] | [
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in mwi, is there a dynamic probability distribution, and if so, what is its characteristic/its mechanics? does local reinforcement of a choice increase the amplitude of the choice across multiple realities? | dynamical probability distribution, ordinary quantum mechanics, dynamical probability ====== you aren't providing a whole lot to go on here, but the "dynamical probability distribution" provided by the mwi is exactly the same as in ordinary quantum mechanics. it is given by the born rule. the answer to your second ques... | 4 | [] | [] | [] | [
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is there any evidence for or against the possibility of shields like those in the book dune, by frank herbet. | in the book traditional ballistic weapons and lasers have been made obsolete by the development of a full body shield. the shield works by only allowing only slow moving particles through it. this shield would allow air to flow through normally but would prevent a projectile or beam from penetrating it. (on an unrelate... | interesting prospect, nebulous term, force field ====== a force field is an interesting prospect, and kind of a nebulous term. but i know there's been talk of making body armor filled with non-newtonian fluids. non-newtonian fluids are liquids that act like a solid when impacted with enough kinetic energy. ever had sil... | 4 | [] | [] | [] | [
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is it more effective to perform aerobic exercise with oxygen mask. | define effective, train, trainning ====== define effective. what exercize? what rate? what conditions? what type of mask? what concentration of o^2? your question leads to too many other questions? are you asking if giving your lungs access to higher concentrations of o^2 will assist aerobic output? yes, essentially. y... | 2 | [] | [] | [] | [
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why we see b & w under poor light? | why do we see objects black and white under a really poor light? | kinds of light-sensitive, light-sensitive cells, light ====== for the scope of this question, you could say that our eyes have two kinds of light-sensitive cells. one type detects light/no light (rods), the other detects colour (cones). the cones are less sensitive to light than the rods. so in low light conditions, we... | 22 | [] | [] | [] | [
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why does the lhc detector need to be five stories tall? | combination of reasons, particles, layers measuring ====== for a combination of reasons: the detectors are like an onion, with different layers measuring different things. it adds up. one thing you need to do is to measure the paths of charged particles. this requires at minimum 3 layers (but in practice more, in order... | 4 | [] | [] | [] | [
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does telomere length correlate with death risk? | disease called dyskeratosis, called dyskeratosis congenita, improper telomere shortening ====== there is a disease called dyskeratosis congenita that is thought to be the result of improper telomere shortening. people with it have multi-organ system issues, especially in tissues that are rapidly replicating (bone marro... | 4 | [] | [] | [
"http://www.wired.com/images_blogs/wiredscience/2011/05/telomere_graph.jpg",
"http://www.wired.com/wiredscience/2011/05/telomere-testing/"
] | [
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what if someone mixed two kinds of proteases in a beaker and had them "cockfight"? | in my molecular biology class, we were discussing protein modification and the ways in which one rna transcription can result in multiple proteins. for example, a polyprotein is produced when one large rna transcript is made into one large protein, which is then subsequently cut into multiple smaller functional protein... | drunk i guess., guess., drunk ====== well quite drunk i guess.. anyways i think the main question is what type of proteases you are talking about. some cleave at very specific sequences while others are more broad spectrum. it will just mean that the ones that are fastest will last longer, but do remember that protease... | 3 | [] | [] | [] | [
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how can i calculate the optimal path for a particle through a set of points? | given a set of points on a 2d plane, and assuming no friction, how would i go about finding the quickest (or at least a close to optimal) path for a particle through these points assuming that i can change the angle of acceleration as well as the amount of acceleration up to a constant. for example, say i am flying a r... | optimal control theory, calculus of variations, optimal control ====== look up optimal control theory and the calculus of variations. this stuff is pretty high level though. you are looking for the functions thrust(t) angle(t) (it may end up better to change to functions of x or arclength or something rather than time)... | 8 | [] | [] | [
"https://en.wikipedia.org/wiki/Automatic_differentiation"
] | [
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why do atoms in the stern-gerlach experiment always scatter into two bands? | my understanding of the experiment is that each band is created by one of the possible values for an atoms magnetic dipole moment. i also thought that magnetic dipole moment was based on both the spin and the angular momentum quantum numbers, meaning that there should be always an even number of bands (as opposed to th... | orbital angular momenta, splitting is based, specifically pick atoms ====== the splitting is based on the total angular momentum of the atom, which is the sum of the spin of the nucleus plus the spins and orbital angular momenta of all of the electrons. they specifically pick atoms where this sums to 1/2 so that there ... | 6 | [] | [] | [
"https://en.wikipedia.org/wiki/Hyperfine_structure"
] | [
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