title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"What is the slowest speed the human eye can observe to see its movement?"
] | [
false
] | For example, a plant is always growing but in most cases we can’t observe that growth with our eyes in real time. What is the speed of something before it is impossible for the human eye to recognise that it is moving? I have tried to search this up many times but it has never answered to my liking. Thanks. 🙂 | [
"What we perceive as apparent motion is created by sequences of frames portraying a stimulus at different locations. Our brains do not view the world as one continuous motion but rather the combination and processing of \"percepts\". You can think of it like a film, where each frame is combined and processed to pro... | [
"Depends on what you mean by observe movement.",
"Persuade a plant to grow with a ",
"vernier scale",
", and you'd probably be able to notice movement. Over the scale of minutes to hours, you'd notice growth in some types of grass if you had a vernier scale on it.",
"OTOH, stars that are far away may move a... | [
"I think what they’re asking is more about being able to watch it and see it grow in the moment. Kudzu grows a foot a day so if you waited a few hours you’d see the growth, but I think the question is about the minimum speed you can be able to see the motion of its growth, rather than just notice the growth. I just... |
[
"Why are marine mammals so intelligent?"
] | [
false
] | Why are the majority of mammals which live exclusively in water (whales, dolphines, porpoises) so highly intelligent? From beluga whales blowing ring bubbles to entertain themselves, to the whale putting on a show possibly as a reward to its human helpers ( ), to dolphins using sea sponges to protect themselves while g... | [
"The evolution of cetacean (dolphin, whale, porpoise) intelligence is poorly understood due to the relative difficulty of determining brain characteristics from fossils until very recently. I should point out that the higher level of intelligence is mostly contained to the suborder of odontoceti (toothed whales) an... | [
"This isn't a reddit post, this is a goddamn one-man wikipedia article. My hat off to you good sir."
] | [
"This is not a satisfying answer though. ",
"Why do tigers have stripes?",
"Which is the better answer: 1. Because having stripes helped them survive to produce more offspring, or 2. Because having stripes breaks up their outline against their background, making it harder for their prey to see them, and thus ea... |
[
"How is norovirus able to withstand the low pH of the stomach?"
] | [
false
] | In order to infect the GI epithelium, norovirus would have to survive the low pH of the stomach. I thought most proteins denature at a much higher pH. What is special about norovirus that makes it so resilient to acid? | [
"Well yes, most proteins we know of do denature at very acidic (or basic) pHs. The key word though is 'most'. The norovirus capsid is pH stable down to a pH of about 1 and the stomach typically approaches a pH of 2 IIRC. The virus capsid proteins do unfold at about a pH 10 though.",
"Here's a nice paper looking a... | [
"I vaguely recall that h.pylori also has a proton pump protein in it's cell membrane to pump H+ out of it's cytoplasm and back in to the environment as well.",
"I think a lot of GI bacteria get to the GI through sheer weight of numbers. If 99.99% get destroyed in the stomach then a couple might still make it thro... | [
"Thank you! This is a great answer. I recall from microbiology h. pylori is able to buffer H+ by producing ammonia via urease. It also burrows into the mucus lining of the lumen to protect itself. I'm not sure how e. coli and salmonella does it, though. That's an interesting question."
] |
[
"Could I eat my own arm or leg to stay alive longer?"
] | [
false
] | [deleted] | [
"Yes, assuming that the energy lost from amputating a leg (I am going to assume leg, since a proper amputation needs two hands) is less than the energy gained by consuming it. As far as how long your leg would last you, it depends all on your body, both your metabolism and how nutritious your leg is. You can surviv... | [
"Gak! Actually, you could survive without food for much longer. Gandhi lasted 21 days and hunger strikers have lasted well over 40 days. Perhaps you should hold off removing your leg!"
] | [
"I realize this doesn't provide any actual evidence, but you should read Stephen King's short story called \"Survivor Type.\" It's about a very similar situation, and he claims he had discussions with a doctor and everything in it is at least plausible. "
] |
[
"The space program has used CO2 scrubbers for ~50 years. Why can't we use this same technology to help clean the atmosphere?"
] | [
false
] | I don't understand why we don't have some capture device on our vehicles to collect CO2. I'm kind of thinking a cartridge type filter, perhaps similar to the ones made famous in Apollo 13. I have some ideas, but I don't really want to push the discussion in any direction before it begins. Edit 1) I'm thinking of an u... | [
"My understanding is that the production and recycling of CO2 scrubbers takes a significant amount of energy, greater than the amount of CO2 that is absorbed from the production of a similar amount of energy. IE it still leads to a net increase in CO2, it just decreases it locally. "
] | [
"Then why not just use the clean energy directly and not generate the CO2 in the first place?"
] | [
"It is largely an issue of size, temperature and time scale, though price cannot be discounted. Here is a link describing the method used on the space shuttle:",
"http://web.archive.org/web/20071031085108/http://www.hamiltonsundstrand.com/hsc/proddesc_display/0,4494,CLI1_DIV25_ETI5338_PRD776,00.html"
] |
[
"Could covid antibody tests be more efficient from blood mixing?"
] | [
false
] | Just an idea I was thinking over. Since covid antibody tests would be positive if EITHER of 2 mixed blood samples but negative if NEITHER did, theoretically, by using a method of mixing 2 blood samples and then one person come back with equally certain results for 1.5 average tests rather than 2 (if 50% of the populati... | [
"It's called pool testing , they just started rolling out limited testing using this with the CoVid test, not the antibody test. Obviously testing and validation must be done prior to approving pool testing with a given test , that's basically what were waiting on.",
"https://www.cdc.gov/coronavirus/2019-ncov/lab... | [
"This can be done and in certain circumstances it is but there are so many considerations it's probably not worth it for this use case. This is the sort of thing that sounds good to e.g. a computer science student because the overhead that applies to clinical samples does not (generally) apply to data.",
"For one... | [
"Thats pretty cool, didnt know about this and I'm glad theres a name for it"
] |
[
"How does Obama's basic research budget compare to Bush's?"
] | [
false
] | I was watching the PBS documentary The Atom Smashers and a lot of the interviews focus on the budget cuts for basic research which crippled Fermilab during Bush's second term. I was wondering if anyone could tell me or point me to an easy place to find out if Obama had done anything to increase basic research funding i... | [
"Courtesy of the Obamameter:",
"http://www.politifact.com/truth-o-meter/promises/subjects/science/"
] | [
"The Obama stimulus was pretty generous to science, though may hurt hard when it disappears and there are more scientists competing for less grant money.",
"That said it is a myth that \"Bush\" was bad for science budgets as opposed to it just being a horrible time for budget funding. It is true that the FY08 bu... | [
"Well there's a huge gulf between modern particle physics and weapons development and virtually no area of overlap. I've never met a modern particle physicist who thinks their research will have an iota of an impact on weapons development. Many actually go into the field, simply because they see no applicable use... |
[
"Can a quantum observation be undone?"
] | [
false
] | I was reading about the various interpretations in quantum mechanics and about the wave function collapse and was wondering whether the process can be reversed. If an observer is rendered incapable of transmitting the result of an observation (e.g. destroyed immediately after), would multiple observers, theoretically, ... | [
"http://en.wikipedia.org/wiki/Quantum_eraser_experiment"
] | [
"Is there a formula for the time a state takes to revert to a superposition?"
] | [
"After a quantum system is measured, it's wavefunction collapses to that of one of it's eigenstates (essentially one of the many possible 'answers' to the measurement). If you continually re-measure the system faster than it can return to it's original quantum state that was a superposition of many eigenstates, it ... |
[
"We know world's fastest creature both on land and sea, in terms of distance/second But what is the world's fastest being in terms of body lengths/second?"
] | [
false
] | I was watching a Nat today while I was brushing my teeth and I thought holy shit, that tiny tiny tiny bug is hauling ass compared to its size. Like I'd imagine if a human we're able to cover it's equivalent body length/sec we would be super Sonic. Am I wrong? Is it truly not that fast? I would assume the smaller the an... | [
"I don't know if it is the record but here is 1000 times the body length per second: ",
"Copepod"
] | [
"Borg et al. 2012",
" is the original article on this if anyone's interested. The ",
"relevant figure",
" does indeed show some of the smallest individuals just barely hitting 1000 body lengths per second in the top left corner, though most individuals are significantly slower.",
"I think another contender... | [
"If you were curious about Air - then its Annas Hummingbird!",
"“ Scientists calculated that the 50mph speed of the hummingbird at the fastest point in its descent is equivalent to it moving 383 times its body length each second. The G-force as it turns out of its dive is nearly nine times the force of gravity – ... |
[
"To the best of our knowledge, with which Earth species do humans share the least DNA in common?"
] | [
false
] | I remember learning in an introductory biochemistry course several years ago that share ~97% of our DNA with bananas, and ~99.9% with chimpanzees. Today I read on this from February, 2013, that the notion of our DNA being so similar to chimps is, in fact, false, now that we've had more time to dissect the human and chi... | [
"There are an awful lot of bacteriophages and archaephages with which you share zero sequence homology. ",
"That said, among cellular organisms, you wouldn't really be able to generate a properly satisfying answer with the kinds of data and statistical analyses we have available - where measuring relatedness is ... | [
"Thanks for the answer, that's what I was worried about encountering as a boundary with this question... guess I'll repost in 20 years or so...."
] | [
"Also, keep in mind that DNA sequence is only part of the picture. DNA is chemically modified to control expression. So even though chimps and humans share so much homology, it doesn't mean the genes act in the same capacity since this epigenetic modification is different.",
"I question that we have 97% sequence ... |
[
"Why are Neanderthals classified as a different species from Homo Sapiens?"
] | [
false
] | If they can mate and form viable genetic offspring, what makes them a separate species? Please feel free to apply this same line of logic to all the other separate species that can mate and form viable offspring. | [
"I don’t believe they are always considered a separate species anymore. IIRC they are often classified as ",
" (with anatomically modern humans being ",
"). ",
"Part of the confusion stems from how species work. We’ve applied a relatively rigid system of classification to something a lot more fluid. For insta... | [
"Speciation can happen both from inability to have viable offspring and from behaviors or geographic locations that create barriers to having viable offspring.",
"Speciation is also considered a more gradual thing than a lot of people realize.",
"Finally, there is evidence that surviving Neanderthal genes in mo... | [
"Ring species",
" are a good example of how the underlying biology is much more fluid than our definitions"
] |
[
"What are the effects on your health of cold and warm showers?"
] | [
false
] | null | [
"The direct effects are seen as a constricting of the blood vessels under cold conditions due to the affinity of the post junctional alpha-adrenoceptors for norepinephrine. \nWarm showers do the exact opposite with the end result being net vasodilation.\nLook into the work of Shepherd and others"
] | [
"This comment has been overwritten by an open source script to protect this user's privacy. It was created to help protect users from doxing, stalking, harassment, and profiling for the purposes of censorship. ",
"If you would also like to protect yourself, add the Chrome extension ",
"TamperMonkey",
", or t... | [
"Upon review of the literature it would seem that both have their benefits. Though not many people have conducted studies that include both variables. There has been some independent research done on one or the other variable. The literature would seem to suggest that both can be used in medically advantageous wa... |
[
"Why does sunlight cause the colors of objects to fade over time?"
] | [
false
] | [deleted] | [
"Most of the pigments we use to give colour to objects are organic pigments. Organic pigments happen to have lots of chemical bonds in them that can be broken by exposure to visible and ultraviolet light. So put enough light into them for a long enough time and the compounds that give the object its colour in the f... | [
"It may be because red needs to fewest amount of bonds to make, thus breaking any of them gets rid of the color. Also more bonds increase the stability of the system."
] | [
"Speaking as an ex organic chemistry tutor, the answer is ",
" stability.."
] |
[
"Has there ever been a period of time (however brief) other than now, that humans lived through a temperature change as rapid as the one predicted to occur?"
] | [
false
] | I remember hearing somewhere that humans once lived through a brief period where the temperature rapidly changed like it is now, and the we survived. Is it possible this could happen again? | [
"One common theory of human evolutionary history says that our intelligence is a product of a rapid cycle of climate change and the adaptability that survival required. Ice ages and warm periods do happen. In fact, after Neandethal man had left Africa and was doing well in Eurasia, between something like 200, 000 a... | [
"Indeed, homo sapiens wouldn't be that dominating if not for the constant climate changes and his adaptability. "
] | [
"This also assumes a problem though. I mean the temperature has been increasing before humans began to have an affect, and has been higher in the past.",
"Unless the goal is to keep the temperature ideal for humanity, climate change isn't a real problem."
] |
[
"Why is the light frequency spectrum cyclical like the audio frequency spectrum?"
] | [
false
] | EDIT: *NOT. Why is the light frequency spectrum NOT cyclical like the audio frequency spectrum? I'm not sure if all my terminology is correct or my explanation makes any sense, so apologies. I'm calling the audio frequency spectrum cyclical in that when a frequency doubles (eg from 220Hz to 440Hz) the pitch heard is mo... | [
"Light and sound are both waves, but we detect them in very different ways. When a sound wave comes in, it vibrates the ear drum, which, through a linkage of bones, vibrates a fluid in the cochlea, which then vibrates a nerve. This nerve is then sending an electrical signal to the brain telling it exactly what freq... | [
"the only answer i can give you is because light isnt really a wave.",
"i mean in some ways it does behave as you describe, we just dont perceive light and sound the same way we cant even perceive directly more than a fraction of the total spectrum. but you can often treat them similarly.",
"individual quanta l... | [
"We can perceive sound from approximately 20 to 20,000 hertz. We can see light from 4x10",
" to 8x10",
" That's a frequency range of 400,000,000,000,000 Hertz. Octaves are tools used mostly by musicians. They are not a unit of measurement. The radio spectrum covers more octaves than audio. I'm rambling....",
... |
[
"How did scientist/mathematicians come up with things such as fourier/z transform?"
] | [
false
] | How did they prove it at the time? Was there a need to come up with something like this to solve an existing problem or was it to simply test correctness of proof and optimizing existing methods? Are there any books or videos which go through how some popular theorams and proofs were derived an stories behind them? | [
"The main theorems and proofs we see today are not what would have been seen when the ideas were first coming around. The idea for Fourier series had been teased at by people like Euler, Lagrange and Gauss, but not enough to recognize a more general theory. This was in the context of physics problems governed by di... | [
"Regarding the need for discovering the transforms: I sometimes think of solving problems in physics as trying to find the \"correct\" coordinate basis to work in. If you try to solve a problem naively, it's almost always very difficult, but if you find the \"correct\" coordinates to work in, the problem becomes re... | [
"It is also interesting how much of the modern* formalism around Fourier series and transforms is inspired by physics. For instance the Dirac delta function was concieved out of physical needs, and later made rigourous through distribution theory.",
"The desire to unify the \"wave function\" aspect and the \"matr... |
[
"Why do slick tyres give more grip when they are hot?"
] | [
false
] | Never made sense to me...tyres are tyres. I am not talking about all kids of tyres though, obviously wet groved ones are going break away when they are super hot, but I am talking about slick racing tyres with no grooves. | [
"Rubber gets \"stickier\" when its hot, for lack of a better term. Physically, a cold piece of rubber will be less elastic and more brittle, which means its not going to grip as well.",
"This is not just for slick tires either. All tires function better when they are warmed up."
] | [
"If you look at a slick tyre when it's cold, it's almost shiny. It has a 'waxy' feel and is quite hard. You can make a mark with your thumbnail. It's hard to describe - almost like a stiff plastic barrel. The tyre is absolutely useless when it is cold. That's why they have tyre warmers before they even attemt to dr... | [
"Ah, I honestly thought they were weaving back and fourth because either A: They didnt want someone to pass them (even tho they arent allowed to), or B: They didnt want to hit the brakes while pacing."
] |
[
"Why doesn't the water in rivers, streams and lakes just go into the ground?"
] | [
false
] | I guess I'm asking how the does water stay above the ground and not seep in? Does it have to do with the water table? Thanks for all the great answers everyone! | [
"Geotechnical Engineer here. Holy hell, I'm relevant on reddit? ",
"As some have pointed out previously, soil has a saturation limit. Varying types of soil may have greater infiltration rates than others. Such as sand versus clay. Sand is a much larger particle than clay and as the particles settle, sand wil... | [
"Just to supplement this, the level of water that lies below the ground is called the \"water table.\" "
] | [
"Just to supplement this, the level of water that lies below the ground is called the \"water table.\" "
] |
[
"If an obese person attempts to lose weight and starts eating healthy, would the plaque on their arteries decrease and/or disappear over time?"
] | [
false
] | [deleted] | [
"Point of clarification, just being obese doesn't mean that there are plaques in arteries (arteriosclerosis). Being obese only raises the risk for developing plaques. ",
"That said, a healthier diet and weight loss in a person that does have plaques can slowly decrease the natural progression of the plaques. "
] | [
"http://www.sciencedaily.com/releases/2008/09/080922155916.htm",
"Aspirin. "
] | [
"There are two major players in the formation of the plaques, cholesterol and platelets (there are others but those are the major two). We have medications that decrease cholesterol (statins, fibrates, etc.) and we have antiplatelets (aspirin). ",
"The body doesn't do anything about them on its own. The plaques f... |
[
"Rude/sexist STEM internship interviewer???"
] | [
false
] | null | [
"Ugh, this is awful. I'd post in ",
"/r/LadiesofScience",
". I think you'll get good advice there. "
] | [
"Thanks! I totally appreciate it!"
] | [
"That's absolutely infuriating and I'm sorry to hear your experience. Unfortunately, AskScience is not the place for this post. I suggest one of the other biology or biotech subreddits.",
"On the bright side, don't think of it as a failed interview, but as bullet dodged. This sounds like a terrible place to be em... |
[
"Why do human beings and dogs have such a great interspecies relationship? Are there other examples in nature?"
] | [
false
] | Can anyone cite research about human beings and dogs and their relationship? Are there other animals that do this? Why? Thank you. | [
"The current relationship between man and canine is known as symbiosis. There are different kinds of symbioses: mutual, parasitic, and neutral or commensalistic. In a mutual symbiosis, both partners benefit. In a parasitic, one benefits, and one is harmed. In a commensalistic, one benefits, and the other is ne... | [
"I feel like this is a bad example of an interspecies relationship. We domesticated the modern dog. We breed the dog based on traits that we found desirable and I will assume that those dogs that obeyed their owners got breed over those that didn't. This steady path of domestication would lead to a dog with a more ... | [
"I think you are referring to the Remora Fish...I don't think a mimosa fish is real...unless there is a fish in the mimosas I like to chug down..."
] |
[
"Do carbon-fiber prosthetics give South African runner an unfair advantage?"
] | [
false
] | [deleted] | [
"At present it is largely a moot point, given that Pistorius himself was too slow to make the individual qualification times - he is not exactly a threat to the likes of Usain Bolt at present."
] | [
"I'm not sure in this case, but I've read that prosthetics are a huge advantage in long distance races where fatigue plays a role."
] | [
"I'm not sure in this case, but I've read that prosthetics are a huge advantage in long distance races where fatigue plays a role."
] |
[
"After seeing the images included on the voyager, would we still include similar images and information today?"
] | [
false
] | null | [
"The messages on the voyager spare craft are practically a novelty, an amusing side project. Yes it may well last for thousands (millions,billions?) of years floating throughout our universe, but the odds of anyone or anything encountering this probe are so low as to be considered zero.",
"Even if an alien specie... | [
"Ah okay thanks for the answer!",
"\"Even if an alien species came across the probe this event would be so far removed from our time scale as to make all information and cultural changes between 1977-2013 irrelevant. \" ",
"This is actually a good point i didn't think of before. ",
"I just thought there are m... | [
"But IF NASA were to make a new \"golden record\" to ensure public favour, what would have changed as compared to the public favour record of 1977?"
] |
[
"Is it possible for vaccines to spread like normal colds/flu? (Through coughing or sneezing)"
] | [
false
] | null | [
"No, vaccines are either fragments of the external portions of viruses/bacteria (i.e. dead bits and pieces), or they're inactivated, meaning that key virulence/reproductive factors have been removed/destroyed/inhibited. Vaccines with dead viruses/fragments can neither spread, nor revert. ",
"Having said that, any... | [
"A few vaccines use a live, weakened form of a virus. For example, the oral polio vaccine. These can potentially spread to other people.",
"See: ",
"https://www.who.int/features/qa/64/en/"
] | [
"The nasal flu vaccine (discontinued I think?) was also a live attenuated vaccine. ",
"The CDC's info sheet says that people who received it should stay away from the severely immunocompromised for seven days, so I assume there is some small chance it could be spread from person to person."
] |
[
"What is the best way to plot the geometry of multiple intersecting magnetic and diamagnetic fields?"
] | [
false
] | Example of some practical questions to tackle are those presented in these demonstrations: Essentially how could you plot the path that electrons are taking when a magnets interact with eachother or when they interact with a diamagnetic. Georgia State University hosts a basic example of magnetic fields which likely we ... | [
"A field is a mathematical description as much as it is a physical one--it describes something that has a certain value (or values) at every point in space. Each point is described by a vector, which in the broadest sense is an ordered list of numbers.",
"The most basic kind of vector that we're familiar with in ... | [
"I'm not sure what your getting at here, he never said you can ignore one magnet. You add the vectors to find the combined effect from both fields."
] | [
"Ah ok, I understand the confusion now. The article is worded for general readers so it's a little vague.",
"I think what they mean to say is not the biggest SOURCE, but the source with the largest contribution at that point in space. As you say, distance plays a large role with the inverse square falloff, so in ... |
[
"Is there a cost-effective way to return spent nuclear fuel to a safe \"ore form\"?"
] | [
false
] | null | [
"You can downblend fuel, but that doesn't change the total amount of activity it has. And anyway, the fuel itself is not the biggest concern with spent rods; there are lots of fission products produced by the operation of the reactor, which are often far more radioactive than the fuel itself.",
"Just some way to ... | [
"Thank you for the insight. ",
"What got me thinking about this was Thunderf00t on youtube made a video where he was walking around in Colorado and just picked up some ore from the ground that was radioactive. I didn't understand why we couldn't chop up the fuel back into such a broken down state that it woul... | [
"Downblending is mixing enriched uranium with depleted uranium to make it less radioactive per unit mass, and less able to go critical. Or generally, you could downblend with anything, it doesn’t have to be DU, but that’s what’s common."
] |
[
"Why does fluid in an IV bag infuse faster the higher it is placed?"
] | [
false
] | [deleted] | [
"The pressure difference between the bag and the iv inlet increases as you raise the bag resulting in a faster flow."
] | [
"It should be noted for clarity that it's the delta between the bag and the patient. (This kind of implies altitude plays an effect in respect to this question - which it does but not for the purpose of this question.) ",
"The liquid is free flowing and effected by gravity separately to the bag/drip feed line. T... | [
"https://en.wikipedia.org/wiki/Fluid_statics#Hydrostatic_pressure"
] |
[
"Questions regarding the expression and inheritance of the X chromosome."
] | [
false
] | This may be outdated or inaccurate but when I was in high school I think we learned that a female has 2 X chromosomes and that when genes that are controlled by the X chromosome are expressed they can be expressed differently depending on which X chromosome is used. It was the current understanding then that there was... | [
"You are mostly correct. Generally, we all have two copies of each chromosome, and there is a phenomenon called genomic imprinting in which one copy of a gene is turned off and the other is expressed. For some genes the paternal allele is silenced, and for others the maternally inherited allele is silenced, and t... | [
"That would be the job of Mr. ",
"Xist",
", a huge RNA gene (it doesn't get translated) that gets expressed only from the copy of X that gets inactivated. If I remember right this RNA coats the inactivated x-chromosome, preventing transcription and is required for x-inactivation. How is the inactivated-copy cho... | [
"for your first question, ",
" ",
"this link",
" is a good start. ",
" ",
" should be able to clear it up for you if you don't want to sift through wikipedia.",
"for your second question, it's a mix of the two. during gamete (ova, sperm) formation, pairs of chromosomes line up and undergo ",
"chromoso... |
[
"How do species evolve new organs?"
] | [
false
] | null | [
" 600 million years ago. The sea sponge eventually evolved to communicate between cells so they can pump in unison allowing for an even higher rate of food gathering. This gives rise to the predecessor for muscles, the hydrostatic skeleton which operates by having dedicated cells contract in unison to fill tiny wat... | [
"This is very informative, thank you!"
] | [
"I'm no scientist, but from what I understand a lot of it is random gene mutations combined with adaptability (survival of the fittest).",
"For example, take eyes. Let's say that a species has no eyes. Eventually a random gene mutation occurs that creates tiny, barely formed eyes. Because the creatures with eyes ... |
[
"Was the Speed of Sound ever considered a theoretical speed limit?"
] | [
false
] | This might be more of a history question, but I'm curious about scientific opinion of the speed of sound. The general consensus is, knowing what we know now, the speed of light is the ultimate speed limit of the universe. Before we could routinely break the sound barrier, was it considered a theoretical speed limit? We... | [
"The 'sound barrier' was never considered a theoretical speed limit while the term was being used. The tips of airplane propellers had been brushing up against it for a long time. Bullets has been breaking it for a long time. The V2 bomb broke it during every flight.",
"The term referred to the many disparate pro... | [
"This entire post is massively incorrect and totally at odds with actual history. Why did you even post this?",
"Yes, or better, it was considered a practical speed limit, in the sense that it was strongly suspected that large objects travelling faster than sound in air were bound to explode.",
"There was absol... | [
"This entire post is massively incorrect and totally at odds with actual history. Why did you even post this?",
"Yes, or better, it was considered a practical speed limit, in the sense that it was strongly suspected that large objects travelling faster than sound in air were bound to explode.",
"There was absol... |
[
"Can somebody explain an event horizon in a non technical way?"
] | [
false
] | [deleted] | [
"When you fall into a black hole it's the region after which you can't get out of the black hole."
] | [
"Yep so the event horizon refers to exactly that. Events are logged by what we can see so if we can't observe within the even horizon, it's the boundary at which nothing can escape. Referring specifically to light is because nothing can go faster than the speed of light and so if light can't escape, nothing can."
] | [
"I thought event horizon referred specifically to when ",
" couldn't escape?"
] |
[
"Does external pain have a \"resolution\" based on the density of pain receptors in the body?"
] | [
false
] | Similar to the resolution of pixels on computer monitor, is there a resolution of pain on the skin due to the density of nociceptors? If so, why do we feel pain exactly where we get pricked by a needle, for example? | [
"There is a test that can be done that looks like a stick with two adjustable pins on it. By poking (gently) the doctor can determine whether you feel one prick or two and the ability to resolve the pricks varies over the body. So the answer to the question is \"yes\" and the second answer is that you don't feel \"... | [
"That's quite interesting. What is this test called and what is the purpose of this test?"
] | [
"Two point discrimination test. Its to determine the sensory density of a particular area, which is loosely resolution. You can do it for different types of stimuli as well, like vibration, not just pain. This image may help:",
"http://dundeemedstudentnotes.files.wordpress.com/2012/04/untitled1.jpg"
] |
[
"How true is it that cell phones can cause infertility if left near a man's testicles for an extended period of time?"
] | [
false
] | Along with that, if true, how long would it generally take for you to become infertile? What about more than one phone? | [
"the level of radiation put out by a cell phone is incredibly low.",
"nobody realizes it, but cordless phones put out much more radiation than a cell. now granted, you don't carry this in your pocket. ",
"and cell phones put or less and less power all the time. as technology advances, the ability to decipher si... | [
"Plus, it makes the screen less likely to be damaged.",
"Also, don't phones emit really low levels of non-ionizing radiation? Doesn't that pretty much make them harmless to biological life?"
] | [
"Cell phones (and wifi) emit radio waves. Radio waves are non-ionizing radiation, and only weakly interact with tissue, so they don't cause tissue damage or sterility, even at high power. ",
"There is no possible way for any number of cell phones to cause sterility or tissue damage via radiation, even if you swam... |
[
"Can humans pant like dogs to cool off?"
] | [
false
] | [deleted] | [
"Yes, but the effect would not be as pronounced as it is in dogs because not as much blood flows through your mouth and the surface area is smaller relative to body size. Your saliva would evaporate leaving your mouth cooler, the same mechanism that sweating uses. ",
"I'm not sure about how much cooling this woul... | [
"You do lose moisture through your lungs... just take a breath in and exhale on something and witness the condensation. If the air is dry enough and cooler than your body, you would lose some heat this way. Exhale on your hand and you can tell with the heat of your breath. However, the volume of air is not great an... | [
"You do lose moisture through your lungs... just take a breath in and exhale on something and witness the condensation. If the air is dry enough and cooler than your body, you would lose some heat this way. Exhale on your hand and you can tell with the heat of your breath. However, the volume of air is not great an... |
[
"\"72% of Americans this...\", \"\"25% of Americans that...\" Where do these statistics come from, who checks them? No one ever asked me anything..."
] | [
false
] | Also what if lets say the surveys are optional, those people who take the surveys are statistically more open minded, etc? Is there a "Department of Facts"? | [
"I worked for Statistics Canada for a while as a student job. I would assume in the U.S. data is collected in a similar way. They either randomly phone somebody or send an in-person interviewer. ",
"With a large enough sample size you can make reasonable valid extrapolations as to the larger population. ",
"In ... | [
"As an interesting aside, a few thousand people, if perfectly randomly selected, will be just as representative for a million people as a hundred million people. That is, you don't need a larger sample to have representative results from a larger population. ",
"What this means is that it's highly unlikely for yo... | [
"For those interested, check out the Wikipedia page on ",
"confidence intervals",
". Using some simple math on your data set, a statistician can say \"I am X% confident that the number you are asking for is between A and B.\" E.g. \"I am 95% confident that the unemployment rate is somewhere between 7.6% and 9.1... |
[
"What exactly is a linear transformation?"
] | [
false
] | This is a basic question I know but I cannot wrap my head around it. I understand the conditions under which a transformation is linear (although I could not tell you exactly what the significance of it is) given here. What I don't get it this. The transformation y = ax + b is non-linear but it is the equation of a lin... | [
"Linear transformations preserve addition and scalar multiplication (as you've said you already know). ",
"Let's see what happens when we try the transformation f(x) = ax + b. ",
"We need f(x1 + x2) = f(x1) + f(x2)",
"f(x1 + x2) = a(x1 + x2) + b ",
"f(x1) + f(x2) = ax1 + b + ax2 + b = a(x1 + x2) + 2b",
"W... | [
"Homomorphisms are important because they preserve structure. ",
"eh, yes, but I would be careful here. Generally, a particular type of morphism preserves a particular kind of structure when mapping one instance of a category of mathematical objects into another instance of the same category.",
"So, a homomorph... | [
"In general, these are called homomorphisms. Homomorphisms have the following properties:",
"f(a#b)=f(a)#f(b)\nf(a^-1 )=[f(a)]^-1\nf(e)=e\n",
"Where e is the identity and # is a binary relation like multiplication or addition.",
"Homomorphisms are important because they preserve structure. (e.g. If we have a ... |
[
"Why don't the veins in the inner elbow crease or pinch when you fold your arm?"
] | [
false
] | I would think it has something to do with blood pressure keeping the walls of the vein pushed out but there's more. What keeps it intact when you bend your arm? | [
"I can confirm that \"wibbly-wobbly\" is the correct scientific term given to the appearance of veins."
] | [
"Veins do crease and pinch shut. Venous blood-pressure is pretty low, and the walls of veins aren't reinforced like those of arteries. Doesn't really matter, though. Veins are the capacitive vessels of your body. The bulk of your blood is in veins at any given time. ",
"If you look at histological slides ... | [
"Two different things. Not only is the course that veins take sometimes convoluted and meandering, but what we are referring to here is the cross-sectional appearance. Cut an artery in twain and it is a very thick, near-perfect circle. Do the same with a vein and it is not nearly as thick-walled and the shape th... |
[
"If someone consumed only sugar water, what nutritional deficiency would be the first to cause them major issues or be the biggest contribution to their death."
] | [
false
] | null | [
"Long before that, the loss of potassium, then probably sodium would cause death. "
] | [
"In a normal, healthy adult with no genetic predisposition, insulin resistance may occur in a ",
" hyperglycemic (overfed) setting, but your pancreatic beta cells will compensate by increasing insulin. It is only when there is combined insulin resistance and beta cell dysfunction (may also see concomitant alpha c... | [
"This. This question is a variant of the starvation /dehydration question "
] |
[
"Why does restmass prevent things standing still or moving with c?"
] | [
false
] | I was thinking about how particles that posses restmass never can reach the speed of light and the same particles can never stand absolutely still, which is implied by quantum-mechanics. Is there a deeper relationship between these two limits for massive particles? I find it interessting that photons (0 restmass) can n... | [
"First off- relativity. ",
"There is one \"axiom\" of relativity- the speed of light is constant in all reference frames. While this is an axiom, it has been experimentally verified, so you don't have to feel bad accepting it. It is from this one axiom that all of the other \"cool stuff\" of relativity comes from... | [
"This video",
" is an excellent answer"
] | [
"could you expand on that distinction between being at rest and not having a definite position? I am still under the impression something as an inertial frame cannot truly exist, since uncertainty in position to me sounds just like moving, more specificly brownian motion which is like random acceleration in all sor... |
[
"49,999 readers! Because reading AskScience was also cool before hitting 50k!"
] | [
false
] | Alrighty, we're officially pretty darn huge by now. 55th largest subreddit, half-way to the big 100,000. Excellent! Since the last State of AskScience post, we have seen a few exciting changes: Slim and improved side-bar, enabled by the nifty that explains our house rules, mission statement, and so on. Improved panel t... | [
"Another thing:",
"Don't just post questions like \"explain acid-base chemistry to me like I'm five.\" Ask a specific question, and someone will answer it but will treat you like an adult."
] | [
"And if you don't understand the answer, you can always ask for clarification on the part you don't understand."
] | [
"Yes, this is actually a matter that should be addressed, and in a positive light:",
"http://www.reddit.com/r/explainlikeimfive",
" is a really nice subreddit which is meant to give you answers that children can understand. They really make no claims about how accurate the answers are, and that's also not the m... |
[
"Does the melting of the polar ice caps contribute to cooling in the atmosphere, similar to how evaporative cooling works?"
] | [
false
] | [deleted] | [
"Yes but...",
"the amount of extra heat absorbed this way cannot exceed the amount of extra heat supplied, that would violate the 2nd law of thermo",
"water absorbs more sunlight than ice because water is darker than ice; over time the additional heat absorbed this way will dwarf the enthalpy of melting",
"it... | [
"Polar cooling events are mostly about containment and redirecting cold that already exists ",
"https://www.businessinsider.com/polar-vortex-dangers-why-it-happens-2019-1",
"The main local arctic thermal variable is color. Dark dirt doesn’t reflect heat as well as bright snow and ice. "
] | [
"I'm in no way able to answer this, but I find it pretty interesting. And just thinking about it: it seems like it wouldn't contribute because ice melts at 32+ F. But the temps in the vortex are well below zero. The ice would have to warm up, then the air would cool the air way back down..."
] |
[
"Given the right conditions and diet, is extremely prolonged life (i.e. significantly greater than 122 years or whatever the confirmed record is) theoretically possible?"
] | [
false
] | Someone posted this link in the TIL subreddit, describing a man who allegedly was at least 197 years old when he died, and lived that long by using his knowledge as an herbalist. I'm obviously skeptical to an degree, but I know next to nothing about biology and aging so I figured I'd askscience. My basic question is j... | [
"Our telomeres, which break off in parts after each cell division, dictate how many times our cells can divide. They are only long enough to support about 140 years of life. After that, when cells die, they aren't replaced.",
"However, cancer will almost certainly occur during that time. Every time a cell divides... | [
"You have an odd definition of proof."
] | [
"The only regimen I've heard of that ",
" achieve meaningful life extension is ",
"caloric restriction.",
" It has been shown to extend the lifespan of many creatures, but the jury is still out on if it can meaningfully extend ",
" lifespan. There are ",
"some signs",
" that it can but nothing conclusiv... |
[
"Why does water evaporate off of ceramic quicker than plastic?"
] | [
false
] | Well I imagine it's because water sticks to the plastic more cohesively. So why? I imagine it has something to do with the electrons. The electrons with H20 and plastic must share some sort of bond that is more cohesive than the random bond-breaking force of evaporation? | [
"Most likely because of higher thermal conductivity.",
"When water evaporates, it cools, which makes it less likely to evaporate. On ceramic, the material can transfer heat back into the now cooler water faster, but in plastic it can't, so the water has to wait longer to get enough thermal energy to fully evapora... | [
"Evaporation happens at the water/air surface, far away from the material the water has contact with. A different surface can influence how a drop of water shrinks, which has a small effect on the surface tension, but I would be surprised if that is relevant. The different thermal conductivity is a more interesting... | [
"As they said; thermal conductivity. ",
"Water binds to itself much more strongly than to either a plastic or ceramic surface, and it's the water-water bonds that are being broken in evaporation. As things evaporate the liquid cools though, slowing further evaporation, so all other conditions being equal (tempera... |
[
"Are certain speech impediments restricted to particular languages? eg: lisps and English?"
] | [
false
] | null | [
"I would say yes.",
"For example, a \"lisp\" commonly refers to misarticulation of ",
"sibilants",
". If a language does not have sibilants, its speakers obviously won't have a lisp (dunno about L2s though...). Examples of languages without sibilants (or voiceless fricatives, in fact): ",
"Hawai",
", ",... | [
"If, by \"lisps\" you mean \"replacement of one sound with another\", then the answer is \"no\". ",
"A \"lisp\" commonly refers to ",
"any articulation problem",
" involving ",
"sibilants",
".",
"French, for example, has the word susseyement[...], which refers for the impediment where /ʃ/ (\"sh\" as in ... | [
"If, by \"lisps\" you mean \"replacement of one sound with another\", then the answer is \"no\". One way of answering this question is to look at whether other languages have come up for words for speech impediments for their own speakers. French, for example, has the word ",
" (also called ",
" and ",
"), wh... |
[
"How does one represent concepts, such as looping, stopping, storing, etc through electric signals (created by binary)"
] | [
false
] | [deleted] | [
"The most basic programming languages are ",
"machine languages",
", which define numerical codes for very basic commands. In a machine language, each instruction is some fixed number of bits long, determined by the processor (",
"). Those bits are then broken down into the opcode, which tells the processor w... | [
"In a machine language, each instruction is some fixed number of bits long, determined by the processor (this is basically what the \"64-bit\" refers to when we say \"64-bit processor).",
"When we say 64-bit processor, that number can refer to a number of things (e.g. virtual address size, data bus width, size of... | [
"The size of the accumulator and other general purpose registers might be a better indication of how many bits the processor is. The 8088 for example had a 20 bit address bus and an 8 bit data bus, but was a 16 bit processor."
] |
[
"Does a hot metal bar lose heat in empty space?"
] | [
false
] | Afaik heat is the cumulative kinetic energy of the metal atoms. If it does get cold, how is this energy lost? There is no matter to transfer this kinetic energy to. I suspect the bar may radiate energy as the (various kinds of) light. But how exactly is an atom's kinetic energy converted into light? The only processes ... | [
"Yes, due to radiation. It doesn't lose heat due to conduction or convection, as it would in normal circumstances."
] | [
"It can become excited in a collision with another atom and then emit radiation as it de-excites."
] | [
"http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/images/irbody.jpg",
"keeping that in mind, you can understand how will the metal object 'lose' it's heat in space. if u would look at it with infrared goggle, u would see it as red and turning to blue"
] |
[
"Do we have vestigial psychology, just like we have vestigial organs like our appendix?"
] | [
false
] | Felt like a really stupid question to ask but wanted to know if there is any real data on it, or if im just not looking at it from the right angle. | [
"Insofar as we share emotional responses with \"lower\" order sentient beings, yes. Human brains have different components you can sort of think of as stacked on top of each other.",
"One of the more basic components is the amygdala. It functions similarly to the entire brain of reptiles. We experience fear an... | [
"I would say no solely in the fact that if we were dropped in a situation that is outside the norm of our day-to-day lives are primitive like old school ways of thinking kick in. It's like fight or flight, how often is that get triggered? But when it does it's life-saving. I think the brains a lot faster and adapti... | [
"The closest things I can think of are some infant reflexes like the Moro reflex. A speculative idea is that it helped baby primates grab their mothers when at risk of falling. Humans don't climb trees of course.",
"https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=90&ContentID=P02630",
"Th... |
[
"Is there a statistically significant difference in any variable depending on the season of the year you were born?"
] | [
false
] | Like a stronger immune system? A higher likelihood of having certain traits? | [
"This is more sociological than biological, but there is something called the Relative Age Effect where the arbitrary dates placed on age groups for youth sports leads to children born towards the earlier dates to be more successful and likely to become professional than the kids born later in the date range. ",
... | [
"There was a study done in Africa where they monitored the life span and health of individuals. They found that people lived longer when they were born in a certain time of the year. The later concluded that this was due to the harvest been present when the mother was carrying the child so nutrients from veg and ot... | [
"Seasonality is a strong predictor of air pollution (its higher in winter) and we now know that pregnant mothers exposed to air pollution can transfer some of it to their developing babies, so in a round about way, season can potentially change things like neurodevelopment through air pollution as a mediator."
] |
[
"Can neural impulses (electrical signals) in a human body be connected to a computer?"
] | [
false
] | null | [
"Sure. See for example braingate."
] | [
"So would it be possible to store memory, think faster, and process information using a computer connected to our brain? Ik this sounds ridiculously sci-fi but is there potential?"
] | [
"We don't know how a lot of information is encoded and stored. For many of these applications, what is happening is that a person is able think of something that produces a clearly identifiable signal. We can then pair that signal to some response in a computer. But it's not necessarily that we know what the person... |
[
"Why are everyone's voices different from each other?"
] | [
false
] | I mean since pretty much everyone have the same designed organs and such, why are our voices all different? | [
"Everyone has ",
"vocal folds",
" which generate roughly sawtooth shaped buzzy tones. We can control the frequency of these tones to a greater or lesser range with a bit of practice and training.",
"On their own, the sound made by these folds would pretty much sound the same for everybody in the world, but th... | [
"Is it possible for everyone to be a good impersonator? Or do you have to be lucky enough to have a more neutral resonance in your skull cavities and stuff?"
] | [
"The vocal folds, explained previously, buzz. On their own they sound like a kazoo. These, along with the cartilage surrounding them, vary in size, rigidity, and capability. Trained singers have a very dense, calloused, and durable set of folds. Smokers have a destroyed set after heavy use. Alcohol users have their... |
[
"Why don't the heavier elements fall in to the center when solar systems are forming?"
] | [
false
] | As the title says, why is it that hydrogen goes to the center when solar systems are forming? | [
"there wouldn't be fusion happening in the core, would there? ",
"Well, fusion is happening in the sun, isn't it? So the assumption that there would be no fusion at all, isn't correct. You're right however, when comparing two stars of the same mass with different metallicities. A star with less metals will have a... | [
"They do. The sun holds more heavy elements than the mass of all planets combined. Furthermore, the sun was at the center of the primordial nebula. The huge amount of mass gathered even more mass and so it gorwed. The planets on the other hand formed from the leftover after the sun has already formed. The reason wh... | [
"But stars are made up of hydrogen, helium and only trace amounts of everything else. If there was that much of the heavy elements, there wouldn't be fusion happening in the core, would there? "
] |
[
"Can diesel explode due to suction rather than compression?"
] | [
false
] | Could suction pressure be enough to set off an explosion if enough oxygen was mixed in the chamber? | [
"Not really. Diesel requires compression to raise the pressure (and as a consequence the temperature) of the air to their combustion levels. This is why the pistons exert pressure on the gas in the cylinder. The vacuum you'd create by applying suction to this gas would neither compress nor heat it, therefore combus... | [
"No. Inside an engine diesel ignites because of the increased pressure of the compressed air. ",
"\"Suction pressure\" is negative pressure. If pressure decreases, air temperature goes down and therefore there is nothing to ignite the fuel. "
] | [
"Suddenly decreasing pressure will reduce the temperature",
"You would have invented a way to chill diesel fuel (mostly useless), and if you try a different fluid such as freon and loop the fluid around so you compress it outside your house (producing heat) while allowing it to expand inside your house near a fan... |
[
"How complex of a computer could someone build by hand?"
] | [
false
] | Basically, let's assume all the giant manufacturing plants in the world shut down. Humanity is limited to building things using relatively simple tools, with the most complex being something like a soldering iron. If we limited the computer to being, say, the size of an average car, how complex could someone make it? | [
"This fellow built a computer out of relays. Relays are nothing more than electromagnetic switches, and can be built by hand from basic parts such as wire, nails, and metal sheet.",
"http://www.electronixandmore.com/project/relaycomputertwo/index.html"
] | [
"There are current projects where hobbiests are making microchips with pretty low-tech tools. ",
"http://code.google.com/p/homecmos/",
"\n",
"http://hackaday.com/2010/03/10/jeri-makes-integrated-circuits/",
"\n",
"http://hackaday.com/2010/05/13/transistor-fabrication-so-simple-a-child-can-do-it/",
"with... | [
"Hmmm? You can build a processor from individual transistors. Unless the premise is that transistors no longer exist, in which case vacuum tubes wouldn't either. "
] |
[
"How can a computer program can prevent the computer from \"knowing\" its code? (like closed source programs)"
] | [
false
] | In non open-source programs, you can't check the source code from the program, but it still executes and runs on the computer. Shouldn't there be a way to know what that code is? From what I understand it works like a blackbox, you feed it input and it gives outputs acording to the code. But how can it prevent me from ... | [
"There are ways of viewing the code of an executable program, using tools called decompilers, disassemblers, or debuggers, for instance. The thing to remember is that you won't be looking at source code, but rather machine code. Unless it was intentionally compiled with debugging symbols intact , you're not going ... | [
"Just to add to this. Op you could view the machine readable code inside an executable with a text editor, but it would just look like a bunch gibberish. If you had a program that displays the hexadecimal interpretation of the file you might be able to reverse engineer it, but it would take a lot of time and effort... | [
"Just to add to this. Op you could view the machine readable code inside an executable with a text editor, but it would just look like a bunch gibberish. If you had a program that displays the hexadecimal interpretation of the file you might be able to reverse engineer it, but it would take a lot of time and effort... |
[
"Why does my nose get all runny when it's cold outside?"
] | [
false
] | null | [
"Your nose serves two purposes: to warm and humidify the air. When it is cold and dry outside, your nose works really hard to add moisture to the air coming in through your nose, however some times some of that fluid may start to run out of your nose. Additionally, when breathing out through your nose, the warm a... | [
"In addition, the cilia (little hair-like projections) that beat to move the mucus (produced in the nose) away fail to work in the cold, stopping the natural mucus flow and causing it to drip out instead."
] | [
"The nasal cavity is highly vascularized, that is, it has tons and tons of blood vessels, and they are relatively close to the surface. That's why medications (or drugs) taken through the nose work relatively quickly. Like someone else said, one of the nose's functions is to warm and moisturize air as it enters the... |
[
"Would you do more work on Mars or less?"
] | [
false
] | Watching the film The Martian, we see Mark (Matt Damon's) character breathing heavily after shoveling some dirt. With the low gravity field on Mars should he be that fagged out? | [
"Acceleration is force/mass, so as long as mass is constant, the two are directly related. In fact, the integral of acceleration is velocity.",
"But more to the point, lifting a mass requires an acceleration. By the definition of work, moving a body against a gravitational field requires work."
] | [
"It requires work against gravity and also work against intertia. Have you taken dynamics or just statics? The force transmitted by the shovel to the dirt is eccentric. It is off-center thus requires both a linear acceleration component and a rotational component.",
"My argument is that the work required for both... | [
"Have you taken dynamics or just statics? ",
"Analyzing dynamic problems and evaluating forces is what I do for a living. If you work out the kinematics, you'll find that the moment required to rotate the shovel scales linearly with gravity. So presuming the geometry of the two situations is identical, the factor... |
[
"How do climate scientists correct for historical date from less precise instruments?"
] | [
false
] | I'm not a climate change denier; I accept the broad scientific consensus. There has been one bothersome argument that I can't find specifics on how it is quashed. I originally heard it from that bastion of facts, Dennis Miller, when he said something to the effect of "How can we possibly trust the accuracy of the data ... | [
"Your question come from the premise that old (1800s and 1900s - which is in reality not very old for weather and climate science) instruments are less precise. But, as I see weather sciences, it's not really the case. ",
"Actually, we can trace back the invention of alcool and mercury-based thermometers somewher... | [
"I'm not sure question of OP concern this kind of data. As I read is, he talk about climate for the 2 past centuries (1800s - 1900s). ",
"On of the interests in dendrochronology is modelling of much older climatic trends (in the order of 10,000 B.P. and even more). To achieve this, scientists rely on old specimen... | [
"I'm more familiar with ocean measurements than atmospheric. From the late 1800s to circa 1970s, ocean temperature measurements were taken with high quality mercury thermometers which could routinely measure to an accuracy of 0.05°C and in the right hands could be as accurate as 0.01°C. [",
"source",
"] So th... |
[
"Does the growth rate vary between fingernails?"
] | [
false
] | [deleted] | [
"Since fingernails actually grow with a rate proportional to the to the length of the terminal phalanges (outermost finger bones) [",
"Source",
"], yes, your nail on your little finge should grow a little slower.",
"With the same reason, some people's nails are going to grow faster than nothers'."
] | [
"Weird, I always assumed that the thumb nail would grow slower, but the outermost finger bone there is longer than on the other fingers, so it must grow faster. Well, TIL."
] | [
"Some do grow faster than others, and the older you get the slower they grow. "
] |
[
"Is there a term for the set of valid 'letter groupings' in a language that correspond to one or more words?"
] | [
false
] | null | [
"A list of heterographs. See ",
"this",
" wiki page."
] | [
"That's almost what I'm looking for, but it appears to exclude words that only ever have one meaning (e.g. \"logarithm\", as far as I know, has no homonyms or heterographs, yet is included in this hypothetical list because it is a valid 'ordered group of letters' that can make up a word)."
] | [
"Perhaps I'm not entirely sure what you are asking then. Why would a list of English words include multiple copies of the same word? You could just say a \"a list of all English words such that each word appears only once on the list (i.e. homographs appear only once)\""
] |
[
"Are there any adverse effects that can result from drinking fluoridated tap water?"
] | [
false
] | I ask because I have a somewhat sketchy landlord who tends to buy into all these conspiracy theories. The other day my roommates and I ran into him downtown where he was protesting the municipal government's decision to fluoridate the tap water. He subsequently advised us not to drink the tap water because we'll end up... | [
"There really are no proven dangers. Throughout the years many a person has claimed that fluoride in the water leads to more children with Downs, more bone cancer in males and thyroid problems, along with a few hundred other complaints. None of these claims have been backed by any meaningful research, a few relie... | [
"At the concentrations used commonly, there is no danger to a healthy person. ",
"http://en.wikipedia.org/wiki/Water_fluoridation_controversy#Safety",
"There does, however, seem to be a real reduction in tooth decay."
] | [
"Technically speaking, the wiki page is off on average, daily ingestion amounts. It fails to take into account fluoride present in foods, watered with fluoridated water. But, still not really an issue. ",
"The wiki article also doesn't address the ion interactions that we get with fluoridated water in most com... |
[
"How much alcohol is safe to drink while pregnant? Is it safe at any time during pregnancy?"
] | [
false
] | From a speech I saw from 2 professors from Duke (Bloom and Schwartz-Bloom), many physicians and people still have the notion that drinking during pregnancy is okay in moderation. You can see for yourself the recent discussion on this topic (which severely lacked recent evidence). [1] However, guidelines within many cou... | [
"http://www.bjog.org/details/news/2085661/Danish_studies_suggest_low_and_moderate_drinking_in_early_pregnancy_has_no_adver.html",
"http://news.discovery.com/human/alcohol-drinking-pregnant-women.html",
"Telling someone to drink nothing is just so much easier then saying moderation may be fine. Mostly because t... | [
"From what I gathered, the UK study surveyed women when the babies were 9 months old. That casts big doubt on the accuracy of the data used here."
] | [
"Most of the problems will be apparent when the child is born, especially the facial malformation associated with FAS. However there is also heart defects, spinal defects and mental defects associated with alcohol consumption during pregnancy. And even though most children will turn out okay you should never risk i... |
[
"Pterosaurs are my favorite class of dinosaurs. Quetzalcoatlus had a wingspan of 40 feet and was the largest flying animal to ever live. Are there any theories on how it actually managed to achieve flight?"
] | [
false
] | They are, to me, probably the most fascinating animal that there's ever been. They were . Their size is actually comparable to small planes. But of course, in order for them to actually be able to fly, it would have required major anatomical adaptations. They had to somehow be lightweight despite being such an incr... | [
"The big pterosaurs are indeed incredible animals. Here's the TL;DR of the articles I'm going to cite in this post.",
"Azhdarchid pterosaurs were huuge. They could ",
"look a giraffe in the eye",
" is how huge they were. Probably weighed in at a good 250 kg. In terms of ecology they were probably ",
"s... | [
"The strongest argument I can make for them being flyers (Petrie, haha) is that evolution and natural selection does not support redundant characteristics. Q. northropi had all the physical characteristics to be a flyer. It's physiology is similar to many current long ranging birds like ",
"albatross",
" and ... | [
"Yes, I know. But it's the only way I know at least to indicate to anyone else reading that they existed ",
" the dinosaurs, if that makes sense. Just like how people may not know that there's a difference between Pterosaurs and Pterodactyls."
] |
[
"What would be the scale limits of Nano Quadrotors (flying robots) while maintaining their intended function? Videos inside."
] | [
false
] | [deleted] | [
"Nano is a complete misnomer... ",
"The smallest you can make a Quadrotor is dependent upon the size of the motor to drive all the propellers. So the question is how much money are you willing to spend? You could very well have a very tiny motor, but it would need to provide enough lift to support the weight of t... | [
"Honestly, i'm pretty sure it becomes primarily software dependent in diverse weather conditions assuming you have a good enough quadrotor. All you need is good software and gyroscopes to make the adjustments when the wind tips it over. As for rain, there are a lot of commercial hydrophobic sprays available now i'm... | [
"The limitation is having world sensors integrated onto the vehicle. GRASP only has their vehicles flying in a room with IR sensors mounted on the walls. "
] |
[
"How do we know that the Mariana Trench is indeed the deepest point on earth, if we’ve only explored/mapped 15% of the ocean floor?"
] | [
false
] | null | [
"We've only looked at a little bit of the ocean floor in detail.",
"We've seen the whole thing in a general view, though. ",
"And while that's not enough for really intricate information, it's more than enough to know that there aren't any other 11km deep chasms out there. Those are kinda hard to miss."
] | [
"The entire ocean floor has been mapped. Just look at google maps, open the satellite view and look at the oceans. We know the bathymetry of the oceans very well. But we don't have perfect resolution everywhere. We don't have meter-scale resolution of the ocean floor everywhere. But our resolution is easily good en... | [
"This is a very common misunderstanding that keeps cropping up. The entire ocean floor has been surveyed to about kilometer accuracy, which excludes the possibility of any unknown superdeep trenches.",
"This 15%, sometimes 5% figure comes from various reports about ",
" scale survey data. ",
"Deep trenches al... |
[
"If colors come from light, as part of the spectrum, then how is it possible that non-luminous objects can have color?"
] | [
false
] | [deleted] | [
"How do we perceive objects? You don't directly detect an object when you look at it. The way yours eyes work is as a photon detector. Photosensitive cells in your eyes are struck by photons (quanta of light), and are capable of \"recording\" both the number and frequency that they receive. Number translates to how... | [
"Because the object absorbs certain wavelengths of ambient light, and reflects other wavelengths. The combinations of wavelengths that hit our eye are somewhat arbitrarily converted into 'colors' by the brain."
] | [
"when any form of visible light hits it, it will appear that color.",
"This isn't true. Go put a blue object under a red light. It will appear black, not blue. This is because red light doesn't have any blue light in it for the object to reflect. Similarly, a yellow object will appear red under red light, and gre... |
[
"If an Ephemeris data updates every two hours, how does GPS finds its position accurately?"
] | [
false
] | I just downloaded a set of Ephemeris data and I realised that the satellite position updates every two hours. Does a navigation message includes the same Ephemeris data and if so, how does one find an accurate position with the time information obtained in the nav message? I'm quite confused with the time info in the E... | [
"GPS signals contain both the emission time and satellite orbit data.",
"https://onlinelibrary.wiley.com/doi/abs/10.1002/j.2161-4296.1978.tb01325.x",
" Table 2-1 has the message structure"
] | [
"Oh thanks, I'll check it out!"
] | [
"The ephemeris data is NOT the position of the satellite. It is the *description* of the satellite's elliptical orbit. Using the ephemeris data you can calculate the position of the satellite at any time. Each satellite has an atomic clock that is precisely synched to GPS master time. The time the signal is tra... |
[
"Why aren't lymph nodes impervious to tumours?"
] | [
false
] | This is to do with lymphomas. So why are areas so abundant in Immune receptors so susceptible to tumour growth? Shouldn't areas with high immuno-surveillance be practically impervious? Thank You | [
"Simple answer is because cancer cells look very similar (to your immune system) to normal cells. ",
"Longer answer is that there often is immune recognition of cancer cells (often by natural killer (NK) cells). NK cells pick up more on \"stressed\" cells and cells where things just aren't quite right than do oth... | [
"I like this answer.",
"Also, I'd like to point out that while OP says that the question is about lymphomas specifically, it's important to note that cancers of non-immune origin also can metastasize through the lymph nodes. So immune evasion, even within a lymph node, is not specific to lymphoma. ",
"I'd als... | [
"I couldn't have said this better myself. A++"
] |
[
"How is energy conserved when photons are red-shifted by their emission towards us from objects moving away from us?"
] | [
false
] | I've read other questions that have been asked about when photons which are red shifted by the expansion of the universe, energy isn't technically conserved, but I was wondering if energy is conserved when red shifting is happening solely because an object is moving away from us. If it is conserved, how is it conserved... | [
"I'm not moving relative myself, but I'm moving rather fast relative the Sun. So I have different kinetic energies depending on what my coordinate system is. This holds true both for classical mechanics (Galilean relativity) and with Special Relativity. ",
"But it doesn't matter if you measure things relative one... | [
"Energy is generally not conserved under change of (inertial) frames. One way to see this is that energy is the temporal component of the energy-momentum vector (\\omega, cp) and/or the purely temporal component of the stress-energy tensor. So under for instance Lorentz transformations the energy transforms covaria... | [
"Wow, that's actually really clear! That makes a lot of sense. I suppose the problem is that it is represented as a sort of physical process, e.g. when people say the wave is stretched, it makes me want to think that it occurs like that no matter what perspective you take, whereas it is actually a matter of referen... |
[
"How would having a giant planet in close proximity affect Earth's gravity and the people on the surface?"
] | [
false
] | The thought came up when my roommate and I were watching a Sucker Punch ad on TV. There is a shot that shows a ringed, Saturn-like planet very close to wherever they are in that movie. I have no interest in seeing Sucker Punch, and in talking about how stupid it looks, I wondered how a huge planet's gravitational pull ... | [
"For starters, the Earth-Moon distance is about 1/100-th the Earth-Mars distance. The moon's mass is 1/10 that of the Earth. The pic in question might indicate another Earth sized planet at a moon-like distance. The effects of two large mass in such proximity would show its effects during the planet formation stage... | [
"Visit ",
"Io",
" to find out what it is like. ",
"I guess we would have a lot of trouble with towering tidal waves, earth quakes and volcano activities. "
] | [
"(non-professional)",
"\nhuge tidal shifts, very likely stronger tectonic movement, climate shifts as a planet that size/proximity would likely alter the orbit of the planets around it. "
] |
[
"Why do babies try and put everything in their mouths? This seems like a huge evolutionary disadvantage."
] | [
false
] | Without constant supervision, almost every baby ever would kill itself within minutes. Is there some sort of advantage to this I'm not seeing? | [
"It is actually an evolutionary advantage.",
"Think of it like this: The process kick starts their little immune systems into getting into fighting shape by putting things in their mouths and exposing it to all kinds of bacteria and interesting micro organisms. You wouldn't want an immune system thats never had t... | [
"Human babies learn an incredible amount in a short amount of time. They don't come prebuilt with a bunch of species instincts, but are instead staggeringly adaptable to different environments/cultures. This constant testing of all objects is part of that. It's the major evolutionary advantage of our species, but ... | [
"I think you are failing to appreciate the selection landscape. Human babies are dependent on their mothers and are helpless. It is not the case that babies have this trait and are free range. An instinct to suckle is a pretty good thing for a mammal. One could certainly imagine that babies without a suckling t... |
[
"Why are robots still so \"jerky\"?"
] | [
false
] | After many years, most robots I see demonstrated/operating still have very jerky movements - it seems odd that they aren't built with motors capable of much finer/more delicate control, and it would be very surprising if such motors weren't available (there must be applications for them somewhere!). Are smoother, finer... | [
"Robots have been used for remote surgery since 2001. There are many motions an artificial structure can make that are much more efficient and more accurate than any human could do.",
"You are considering 'jerky' with respect to humans which are limited by requiring slow steady movement for accuracy. Robots can ... | [
"The robots ",
" moving smoothly. It's just that they are often programmed to move efficiently, which often means perfectly straight lines and a high acceleration, so it doesn't look smooth compared to say a human moving a human hand around."
] | [
"I guess it's only a problem if you're trying to emulate human movements, then, although quite often it does look quite unstable - e.g. the robot stops moving suddenly, causing it to wobble, such as when ",
"this red robot",
" comes to a stand. I'd also imagine it puts more stress on the structural components -... |
[
"How long does it take for asphyxia related death to take place?"
] | [
false
] | In movies and TV shows, anytime a character is choked, s/he always passes out in under a minute and is presumed dead. I understand that temporary loss of consciousness can occur as a result of suboptimal brain oxygenation, as is the case in some fainting spells (or that fading feeling one has when standing up too quick... | [
"Can't really address the specific causes of death, but I will say that the vast majority of tv and movie portrayals of asphyxiation are unrealistic. You would need to continue choking someone for a significant period of time AFTER they lose consciousness in order to kill them. Doesn't make for good television thou... | [
"Physician here.",
"Short answer: the brain will die in 5-10 minutes.",
"Long answer: If the person has had training or preparation, they can hold their breath for ",
"up to 20 minutes",
". Also, if they are immediately cooled... like a drowning in a frozen lake, then they could recover almost completely ... | [
"Understandable about TV. It's an acceptable concession, methinks. Do you think one passes out (or drowns for that matter) with their eyes opened like in TV, or rather with their eyes closed (as I'd imagine most blackouts to occur -- I'm thinking g-force induced blackouts experienced by untrained fighter pilots[soo... |
[
"Is there a way I can safely remove the Americium-241 from a smoke detector?"
] | [
false
] | null | [
"The activity of the americium-241 in the smoke detector is less than 1 μCi, so as long as you don’t swallow it, it won’t really harm you."
] | [
"I don’t advise you to play around with the source in your smoke detector, but when I handle similar sources, I make sure to follow ALARA (dose As Low As Reasonably Achievable), use gloves when possible, avoid touching my body with contaminated gloves, and wash my hands after. There is no food or drink allowed anyw... | [
"So just keep far away from food, cover my skin and wear disposable gloves, essentially? Thanks :)"
] |
[
"Is it possible to improve one's vision without glasses or surgery?"
] | [
false
] | [deleted] | [
"I am an American board-certified ophthalmologist. Let me clear a few things up. In general, nearsightedness is caused from the eye being too long, and farsightedness is due to the eye being too short. There is no way to change this with any type of activity or medication. However, as we get older the lens of the e... | [
"I have amblyopia, a fairly common vision disorder in which the brain ignores input from an eye that is otherwise physically healthy. ",
"A few years ago a VR game called Diplopia was successfully crowd funded, and today it's been renamed Vivid Vision. The VR game forces the brain to incrementally utilize more in... | [
"He et al. (2007)",
" showed renewed plasticity in adult rats and ",
"Duffy and Mitchell (2013)",
" found the same in adult cats following deprivation during adulthood. In humans: ",
"Zhou, Thompson, and Hess (2013)",
". See also ",
"Mitchell (2013)",
" and ",
"Mitchell et al. (2016)",
".",
"Mor... |
[
"Why is it that planets don't 'twinkle' when viewed from earth?"
] | [
false
] | Why do planets, as opposed to stars, not 'twinkle' when viewed from earth even thought the light from both passes through the same atmosphere? Is it that stars, due to their relative distances, behave as point source of light? | [
"Yes, basically. It has to do with the relative ",
"angular diameter",
" (width) of the two bodies in the night sky.",
"Jupiter",
", at ~140,000km in diameter and ~700,000,000km away has an average angular diameter of ~40 arcseconds, which is right at the limits of resolution for the human eye.",
"Sirius... | [
"It has nothing to do with the number of photons ",
". If Sirius appeared as bright as the sun, we would be receiving the same number of photons per second from it as from the sun, but it would still appear to twinkle because of its small angular diameter."
] | [
"In other words, stars are basically point sources."
] |
[
"Why is there no medical approach based on how plants fight infections?"
] | [
false
] | null | [
"What a douchelord"
] | [
"What a douchelord"
] | [
"Questions based on discussion, speculation, or opinion are better suited for ",
"r/asksciencediscussion",
"."
] |
[
"If we dropped an atomic bomb into a hurricane at the right spot, could it \"kill\" the hurricane?"
] | [
false
] | null | [
"Similar question asked earlier in the week (I think) this is the only one I could find on it (3 months old): ",
"http://www.reddit.com/r/answers/comments/hpb8b/could_you_disrupt_a_weather_pattern_with_a/",
"also just found this ",
"http://www.reddit.com/r/AskReddit/comments/fcebk/if_an_atomic_bomb_was_droppe... | [
"Thanks! Apologies for the repost-ish. :)"
] | [
"No props :)"
] |
[
"The boiling point of carbon dioxide is -57 °C. The coldest recorded temperature in an inhabited place is almost -68 °C. Does this mean that carbon dioxide condenses out of the air in these places?"
] | [
false
] | This is what got me thinking: . Furthmore, the lowest recorded natural temperature anywhere on earth is -89.2 °C , colder than the freezing point of CO2. Would carbon dioxide ice freeze out of the air under those conditions? | [
"At 1 atm it wont form a solid until -78.5 C.",
"CO2 Phase Diagram"
] | [
"I don't want to rain (CO2 frost) on the parade here but Vostok Station is at an altitude of 3,488 meters (or 11,444 feet) and ",
"this site",
" describes \"atmospheric pressure here is very low comprising 624.2 hPa on average for a year.\" ",
"So about 62% of standard temperature pressure. The CO2 phase chan... | [
"The freezing point of CO2 is really only valid when going from liquid CO2 to solid and at a specific pressure, probably sea level or one atmosphere. The same thing with water if you have water that has impurities it affects the freezing and boiling points the 0 C and 100 C freezing and boiling points of water are ... |
[
"How do antibiotic creams work compared to antibiotic pills, and is there also a risk for over using it as well?"
] | [
false
] | null | [
"Depends on what you’re treating, the drug that is applied, etc. typically you don’t use the same antibiotics as creams and pills. You would use a topical cream for most skin infections, but if you needed to treat a pulmonary infection, you wouldn’t want to slather someone’s lungs in cream. There is a risk with ove... | [
"As for the second part, yes, there is a big risk for overusing it, but not in the way you think. Using antibiotics all the time will start triggering evolution within bacteria, creating strains that are completely resistant to antibiotics, eventually creating a superbug. This is already going on, and the best exam... | [
"Antibiotic creams is specially formulated to work on applied area. Antibiotic pills need to be ingested and some drugs (pro-drug) will need to be metabolized to its active drug before it can circulate the body and do its work.",
"Antibiotic cream is prescribed especially for local skin infection (e.g skin ulcer)... |
[
"i found a mysterious science object. what is it?"
] | [
false
] | i was walking down the burke-gilman trail, close to the university of washington, and i found this odd thing hidden in a wooded grove. it comes up to my knee, and weighs maybe 30 lbs. does anyone have any idea what it is? | [
"I believe you're right. It's a picture of an eight quartz lamp heater array mounted to a custom made flange with huge heat sinks. This is a furnace that could have been a part of a chemical vapour deposition setup. Hard to tell. There are many applications that would require this type of heating.",
"Those golden... | [
"It reminds me of a lot of the ultra-high-vacuum equipment I've seen, but... is it open at the sides, or does it have thick solid walls?",
"edit: Example of what an UHV chamber might look like: ",
"right here",
"The roundness, the stainless steel (possible gold plating?) and screw holes remind me of this kind... | [
"What's on the slabs of PCB at the center of the parabolic reflectors? A great honking set of LED emitters? ",
"I have no idea. But from looking at it, we can see a few things:",
"In general, it looks set up to do ",
" with a lot of power, probably involving light aimed at the center. If the other end was... |
[
"With solar panels being so \"shiny\", doesn't it affect their ability to absorb the sun light?"
] | [
false
] | I saw this picture and was puzzled how their surfaces could be so shiny: Does the material have other benefits which makes up for the glossy effect of it? Is any sun light lost because of the shinyness? | [
"The picture you posted is taken at an oblique angle. As you increase the viewing angle, the reflectivity grows until it reaches 100%. If you looked at those same panels straight on, they would look almost black.",
"For that reason, you always want solar panels to be facing the sun. One of the main areas of resea... | [
"One of the main areas of research in solar tech is figuring out cheap ways to make panels track the sun.",
"What do you mean by this? I'm imagining we have enough information about orbits to accurately predict the Sun's position in the sky on any given day, so it simply using that information that is being resea... | [
"Tracking for a single panel with clearance around it increases daily output only marginally, whereas tracking panels packed adjacent in an array will actually REDUCE the array output dramatically.",
"Say you have 1000 sq ft of south-facing roof. The panels are all packed together. The ROOF can't turn to face t... |
[
"Why do my computer speakers occasionally pick up AM radio stations?"
] | [
false
] | I went to plug my computer speakers into my laptop today, and if I only half plug in the line-in cable, I can hear a local AM radio station (specifically WLS890 Chicago) playing under static on my computer speakers. What's the explanation there? | [
"http://en.wikipedia.org/wiki/Antenna_%28radio%29",
"Something in your computer or case is acting as an antenna that is matched to that local station. ",
"For some reason when the cable is only half plugged in, the circuit is delivering that station to your speakers. Not sure why this is the case here though."
... | [
"AM = Amplitude Modulation. So there's a frequency in the air that's getting stronger and weaker to directly model the waveform of a sound. (This is important, because FM doesn't do this)",
"Your computer case is acting as an antenna. When the cable is plugged in halfway, this is probably connecting the signal pi... | [
"This would be more fitting in ",
"/r/electronics",
" or ",
"/r/AskEngineers",
"."
] |
[
"If two astronauts are indefinitely moving away from each other at a constant speed, who is aging slower?"
] | [
false
] | Was reading about the twin paradox earlier and I can accept the age difference resulting from the acceleration needed for the twin to turn around. But what would happen if the twin just didn't come back? Assuming they are already moving away at constant speed from the start | [
"Each twin would determine that the other twin was younger than themselves. No one would be able to determine which twin was \"really\" younger, because there's no such thing. This is one of the consequences of the relativity of simultaneity, which is the idea in special relativity that there's no way to uniquely d... | [
"That's completely incorrect. Time dilation ocurs between any two reference frames that are moving relative to each other, including constant relative velocities. Acceleration greatly complicates the matter, but is not necessary for time dilation."
] | [
"That's completely incorrect. Time dilation ocurs between any two reference frames that are moving relative to each other, including constant relative velocities. Acceleration greatly complicates the matter, but is not necessary for time dilation."
] |
[
"Why do transformers only work with alternating current?"
] | [
false
] | null | [
"Transformers make use of the fact that a changing magnetic field can produce a voltage - this is Faraday's law of induction. It's not the absolute value of the magnetic field but its rate of change which is important.",
"Direct current has a constant electric (and hence magnetic) field across the coils and so is... | [
"So, basically, what is ",
" happening is the same thing as moving a magnet relative to coils of wire?"
] | [
"A good answer is provided ",
"here",
". Basically, the reason is that DC cannot create an alternating magnetic field which is needed to make the electrons in the second coil move."
] |
[
"What would happen to an object that fell onto a gas planet?"
] | [
false
] | Lets assume theres a planet fully made of gas, like neptune just without the massive core. What would happpen if I threw a rock at that planet? The planet should have gravity but because theres no solid core, the rock cant really hit anything and therefore land. Would it just fall through the core and then return to ev... | [
"There might not be a solid core, but there's plenty enough gas for it to ",
"go through and burn up in!",
"There's a thought experiment that wonders what'd happen if you managed to bore a tunnel straight through the centre of the Earth to the other side. If you just jumped in, the assumption is that you'd end... | [
"I'd imagine the gravity of a planet the size of Neptune, even ignoring that compression of particles due to gravity nearing it's centre, creating a denser core, would still have enough gravitational mass to crush the rock, and have it begin orbiting the centre of mass and burn. "
] | [
"Thanks for the answer :)"
] |
[
"Were protohumans able to reproduce year round, or did they have seasonal mating? How far does this trait go back on our evolutionary tree?"
] | [
false
] | null | [
"Well, pretty much all monkeys reproduce year round, so it's probably a reasonable bet that our most recent common ancestor with new world monkeys probably did too. That puts us at least at 40 million years. That said, year-round reproduction in mammals probably more a factor of climate than lineage. If you live... | [
"Followup: is the incidence of seasonal mating proportional to latitude?"
] | [
"Yes, almost certainly. Off the top of my head, I can't think of any terrestrial mammals that natively live in northern latitudes and don't have seasonal reproduction. So I would say that seasonal reproduction is highly correlated to latitude. Exceptions might be animals that are more capable of controlling thei... |
[
"Chloroplasts into humans."
] | [
false
] | null | [
"It would in my opinion be technically possible... eventually. A plant respires like we do so it would seem to be possible although I am sure there are many things I've overlooked (I'm not saying in any way that this is feasible without a huge amount of research).",
"\nHowever, the real question is why you would ... | [
"Energy isn't concentrated as you go up, it is lost as you go up the energy pyramid to higher trophic levels - I believe the rule of thumb is that only 10% of energy at each trophic level is passed on to the next."
] | [
"Yeah, that's what I've heard, between 10-15%. And to answer his question, you could do it in order to stop muscle meltdown (catabolising proteins for energy, when glucose and lipids are unavailable) in nations where there is no or very little food."
] |
[
"Would it be possible to propel a spaceship using only nuclear radiation?"
] | [
false
] | I know this is only theoretical, but would it be possible to design a ship capable of being propelled using only nuclear radiation as it's method of propulsion? I realize the specific impulse of an engine like this would be extremely high, but theoretically, even if only one particle left the original mass we are using... | [
"Yes",
"http://en.wikipedia.org/wiki/Fission-fragment_rocket",
"\n",
"http://en.wikipedia.org/wiki/Fusion_rocket"
] | [
"While i appreciate the links, this is not the radiation i meant. When a piece of plutonium is sitting on a table, it is emitting radiation. I was talking about using that radiation to propel something. The thrust would be almost infinitely small, but it would still be there, and it would last thousands/millions of... | [
"That would be the propulsion scheme from my first link."
] |
[
"Why is there bacteria everywhere? What does bacteria feed on to survive and multiply on the floor for example?"
] | [
false
] | null | [
"Other bacteria. And then when they die, other bacteria comes to capitalize. Then (in water environments) when the process of cellular respiration depletes available oxygen, anaerobic bacteria comes and thrives while reducing sulfur instead (ever step in stagnant muck and it smells like rotten eggs?)",
"In short,... | [
"Prokaryotic or single-celled life has always been the dominant from of life on the planet. From free-floating algae that can alter the atmosphere over millions of years to polyextremophiles that survive the harshest of conditions.",
"Bacteria don't need much to survive but water of course is the most essential c... | [
"Not just other bacteria, but all the organic dust that comes from plants, animals, people, etc"
] |
[
"Conservation of Kinetic Energy in an Inelastic Collision"
] | [
false
] | Experimentally, if a collision is inelastic, yet energy is still conserved, where might the kinetic energy go? Just got curious while studying physics. | [
"Usually inelastic collisions involve rearrangements of the pieces that make up each object. For example, in a crash between two vehicles that stick together, the vehicles will get crushed to some extent, and this will take energy to do. ",
"There are other effects to consider such as if the collision made any no... | [
"It might be transformed to heat, it might deform something involved in the collision... Sky's the limit, and it depends on the circumstances of the collision."
] | [
"Usually inelastic collisions involve rearrangements of the pieces that make up each object. For example, in a crash between two vehicles that stick together, the vehicles will get crushed to some extent, and this will take energy to do.",
"Just as another example: For less rigid objects, some sort of deformation... |
[
"If I consume undercooked beans (still kinda crunchy), do I obtain all the nutrients, or will my body just ignore some of the calories from the nutrients?"
] | [
false
] | null | [
"Don't consume undercooked beans, particularly red or white kidney beans. They have a toxin that is incredibly unpleasant. ",
"See ",
"this wikipedia article",
". Note that undercooked can be even worse than not cooked."
] | [
"Dried pasta is safe to eat uncooked, but you should cook any fresh (or \"wet\") pasta before eating since it may contain raw egg. Dried peas are fine too (wasabi peas . . . drooooooool). Although, I can't guarantee you won't chip a tooth on the pasta."
] | [
"I do cook the beans (usually pinto and chickpeas, the latter which are not beans) for about 30 minutes. But there is still some firmness to the beans. Even after 30 minutes of boiling. I do avoid red kidney beans because I had heard of their toxicity, which I am also aware is not just exclusive to kidney beans.... |
[
"How does the environment of space affect electronics?"
] | [
false
] | Specifically, how can electronics be protected from it? I know the temperatures are a major factor, but I understand that this can be stopped with insulation, cooling or just using electronics that operate in a greater range of temperatures. I'm more interested in the other factors, how they affect electronics, and how... | [
"A relative of mine does this stuff for a living so I can tell you what I've learned by asking the same question. Note that this is a combination of ",
" and what makes sense.",
"Issues that you have to worry about when sending electronics to space:",
"wire bonds",
"As for the cost, there are two factors. T... | [
"part of radiation protection is a different layout for the memory.",
"in your home RAM the bits in a byte are physically next to each other and next to the next byte.",
"In spacecraft the RAM doesn't necessary look like this, apart from using EEC RAM it is also more spread out, so radiation most likely flips o... | [
"Having adjacent bits in the same word/byte is almost never done in any IC memory. Not just to avoid soft errors, but because it doesn't make as much sense to lay things out like that on physical ICs. The most efficient ways to lay out the decoder circuitry that addresses the various bits naturally does not have ... |
[
"If something as small as an atom shot through your body would it be detrimental? Or even a string of atoms being passed, at fast speeds, horizontally through your body."
] | [
false
] | null | [
"The extreme example is ",
"Anatoly Bugorski",
" who had a high energy proton beam go through his head. He was injured, but survived."
] | [
"It was actually a beam of protons, just one wouldn't be that big of a deal. You are kind of right though, in those kinds of high-energy collisions, a lot of energy gets released in the form of radiation. I don't know if the beam had enough energy to cause nuclear effects (essentially, when a proton hits the nucleu... | [
"Alpha particles are just that, they are equivalent to a He2+ atom. Which consists of 2 protons, 2 neutrons, and no electrons. Very few things are smaller than alpha particles including isotopes of hydrogen ( H ). Alpha particles are already too large to pass through your body. However, if the source which emits th... |
[
"What do ants do with their deceased?"
] | [
false
] | I was out on a smoke break today on the wooden staircase outside of my workplace. As I often do, I soak up the feeling of nature around me and enjoy the break from an otherwise hectic day. I noticed a line of ants marching along seemingly conducting business as usual. I noticed the lead ant was holding a deceased ant i... | [
"Ant colonies operate rubbish heaps that are separate from the colony, but nearby. Any undesirable detritus from the nest goes there, carried by worker ants. This includes their deceased comrades. Even ants that have been terminally injured (such as their abdomen cut off) yet are still alive and moving are unceremo... | [
"Ditto. Well, not an ant farm, but I've come across several wild ant colonies that had a \"dumping ground\" with a pile of dead ants and other debris."
] | [
"I don’t know the answer, but I can tell you this: I once was tasked to feed and water a co-worker’s ant farm. I forgot about it for several days and by the time I did remember, several of the ants had died. The living ants moved the dead ant bodies all to a specific area of the ant farm. ",
"I felt pretty ba... |
[
"Why does light travel the same speed for all observers?"
] | [
false
] | To my understanding, if something (say a ship in a vacuum) is travelling away from a light source it would observe photons reaching the ship in [time=d/c], while a stationary observer (with respect to the light source) could theoretically observe photons reaching the ship in [time=d/(c-v)] (where d=initial displacement... | [
"I wouldn't classify it as a \"mystery\" of nature. But it is a postulate, something assumed to be true, based off of a lot of observations. ",
"The postulate arose because people were playing around with the equations that govern electricity and magnetism. You can test each of the 4 equations independently, they... | [
"Well that's kind of my point about the story of this electromagnetism stuff. All observers will come up with the same laws of electromagnetism, regardless of their respective motions (so long as they're uniform and not accelerating). And out of the laws of electromagnetism fall the laws of light. Classically at le... | [
"Maxwell's equations clearly predict the speed of light, without reference to relative motion. There are two ways to interpret that; either the speed of light is the same for all observers, or the laws of physics are ",
" the same for all observers. The latter violates the principle of relativity, which states th... |
[
"Would it be reasonable to consider the human species as Homo Domesticus?"
] | [
false
] | null | [
"No. Domesticus is a subspecies designation for a selectively bred subgroup of another species that has been domesticated. If a group of aliens comes to Earth, takes a small group of humans away and they are bred for certain traits that make them genetically and phenotypically distinct from humans on earth, then it... | [
"Welcome, thank you for asking. "
] | [
"Thankyou."
] |
[
"Is it possible that an “earthquake season” could exist? Or are the earthquakes in my country just coincidences?"
] | [
false
] | I live in Mexico and earthquakes are fairly common here. They happen at any point of the year really but there’s a strange pattern a lot of us have been noticing recently. One of Mexico’s most devastating earthquakes happened on September 19, 1985. Then in 2017, a small earthquake happened on September the 7th. Then, ... | [
"A general response to any question involving apparent periodicity, trends, clustering, etc in earthquakes are that apparent clustering of a variety of types in records of stochastic events (like earthquakes) are typically just that, i.e., apparent not real, and are actually an expected outcome of randomly distribu... | [
"I’ll let this paper by ",
"Hough, 2018",
" answer that question."
] | [
"Yes. You can spend days sifting through the contradictory papers saying that they’ve confidently identified tidal triggering in a given seismic catalog vs the papers saying they’ve confidently rejected tidal triggering in the same catalog. Suffice to say, demonstrating clustering is hard, as described above."
] |
[
"What would happen to a bubble of carbonated water in space?"
] | [
false
] | [deleted] | [
"This is a video of Alka-Seltzer in a sphere of water on the ISS. ",
"http://www.youtube.com/watch?v=bgC-ocnTTto",
"Edit: Here is the same thing while rotating. ",
"http://www.youtube.com/watch?v=BxyfiBGCwhQ&feature=relmfu"
] | [
"hope this answers your question.",
"http://www.youtube.com/watch?v=bgC-ocnTTto",
"(on a related note, how does one make a link out of something that is not a link? i.e. Platypuskeeper's \"like this\")"
] | [
"there is formatting help on the lower right side of the reply box",
"but basically it is [like this]_(",
"http://www.youtube.com/watch?v=bgC-ocnTTto",
")",
"except remove the underscore between the ] ("
] |
[
"If the average human ear was a microphone, what would its specifications look like?"
] | [
false
] | null | [
"Ribbon microphone with huge fleshy ribbon. (DO NOT run phantom)",
"Cardioid with perfect off-axis rejection when installed in HUMAN HEAD mount (sold separately)",
"20hz-20,000hz for first 20-25 years of regular use",
"http://www.audioholics.com/room-acoustics/human-hearing-amplitude-sensitivity-part-1/clip_i... | [
"You ask a fascinating question, and one that requires a complex answer.",
"First, a lesson on what the ear is because I want to let you know exactly what you're asking and this is a topic about which I am very passionate. TL;DR at the bottom if you don't give a damn about science.",
"There are three sections o... | [
"not omnidirectional, more like a figure 8 bent forward once you factor in the shape of the fleshy cartridge ear thing attached to your head"
] |
[
"How does rain come down diagonally with no wind?"
] | [
false
] | I suspect it has a simple answer such as wind at higher elevations? I've Googled and searched Reddit and couldn't find a definite answer. | [
"Your guess at a simple answer is correct. Rain will fall straight downwards unless there is horizontal wind blowing it in a different direction. It is not uncommon for there to be strong winds above ground that don't fully reach the surface, especially if you're in an area surrounded by buildings and/or trees. So ... | [
"In a sail boat, I sometimes can have no wind at the deck but have wind just a few feet higher on the sails. Once the boat starts moving, I get apparent wind on the deck even though I can see from the surface of the water that it is calm. ",
"I imagine the rain keeps moving the direction it was going when it hit... | [
"Thank you for taking the time to reply!"
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.