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[
"[Weekly Discussion Thread] Scientists, do you use the scientific method?"
] | [
false
] | This is the sixth installment of the weekly discussion thread. Today's topic was a suggestion from an AS reader. Topic (Quoting from suggestion): Hi scientists. This isn't a very targeted question, but I'm told that the contemporary practice of science ("hard" science for the purposes of this question) doesn't utilize ... | [
"Speaking from the biological and medical sciences, I can say I use the scientific method closer to the way it is defined by Karl Popper than by the way it is defined by grade school science teachers. It is infinitely frustrating to have to instruct every year of graduate students that you advance science by reject... | [
"Speaking from the biological and medical sciences, I can say I use the scientific method every day. It's more of an automatic process going on in a scientist's thinking than any kind of formal breakdown into steps. Practically speaking, the scientific method is a cycle that can be entered at any point, as an obser... | [
"Probably this won't surprise anyone, but mathematicians certainly don't use the scientific method in a recognizable form (although there's more observation → hypothesis → experiment than you'd expect in the craft of mathematical research)."
] |
[
"Light has been slowed way down and observed, but where did the energy come from to speed it back up?"
] | [
false
] | So there have been experiments that have slowed light down enough where we could observe them, but then as the particles pass through the experiment, they speed up again to their normal speed. How? You need some kind of force to speed up or slow something down. What is making the light speed back up again? | [
"So the answer to the question about energy is pressure energy. Non-straight motion energy is said to be pressure energy.",
"And that's where the force comes too: pressure."
] | [
"I don't really know which experiment you are talking about, but it has most likely to do with quantum entanglement and nanoscopic mirrors, or the manipulation of phase or group speed. None of them actually slows down single photons, they only interact with the beam as a whole, causing strange speeds to appear, but... | [
"They were talking about it on NPR yesterday. It was one of the sciencey shows (Radio Lab) they have and they interviewed the lady that developed the experiment. Sorry for not having more info on this but going by memory, she slowed down light down to something like 17 m/s using a bunch of lasers, so while the li... |
[
"If atoms are made up of protons and neutrons and protons and neutrons are made up of quarks, then what could quarks possibly be made up of?"
] | [
false
] | null | [
"As of right now, we don't think quarks are made of anything besides quark. There has to be some \"lowest layer\", and we think that quarks are that lowest layer for neutrons and protons and the like. All experiments we have conducted seem to show that quarks are fundamental, but it's also possible they're made of ... | [
"And what might strings be made of? is it turtles all the way down?"
] | [
"This right here. The standard model of particle physics is to (what we currently believe are) fundamental particles as the periodic table is to elements. The only other option at the moment is string theory, but it's yet to achieve experimental validation. "
] |
[
"What is the best (and most realistic) option for a warp drive?"
] | [
false
] | null | [
"There isn't a realistic one."
] | [
"But what about Alcubierre drive?"
] | [
"The Alcubierre drive wasn't meant to be taken seriously as a method of propulsion, it's just an interesting theoretical result of applying general relativity. It would need negative energy densities to work, which don't exist."
] |
[
"How fast am I going?"
] | [
false
] | [deleted] | [
"Relative to what?"
] | [
" because it's a great question (perhaps it gets asked regularly); the answer is pretty mindblowing, to me :D ",
"The question is in fact meaningless, because it assumes the existence of something called ",
". It is in fact not possible to take an object and measure its velocity in such a way that every observ... | [
"Asked a number of times in the past",
"."
] |
[
"Will a power outlet that has a lower number of amps than is typical (i.e. 9 amps vs. 15) not be compatible with some electronic devices?"
] | [
false
] | null | [
"Typically no. Unless the device requires more current than the outlet is able to provide, which is unlikely with small electronic devices. Most electronic devices are even compatible with a range of voltages, instead of only operating on a single voltage."
] | [
"So my electric piano has 13 watts of power consumption and has this kind of power supply \"Power supply (DC12V 3.5A), POWER switch\"",
"http://www.korg.com/us/products/synthesizers/krome/page_4.php",
"This is what I've heard about the power outlet at the place I'm going:",
"\"About 9 amps. Enough for fan, co... | [
"Absolutely enough. The 3.5A is the maximum current that your device would need. So 9 amps would be more than enough."
] |
[
"Some deeper questions about the double slit/quantum eraser experiment"
] | [
false
] | Hey guys. I recently stumbled upon the and my understanding is that, when they set up recording devices that automatically delete what they recorded after the particles land, the particles form an interference pattern. If it doesn't delete the information, they don't interfere. To me, this is absolutely astounding, tha... | [
"Can you give me a link to where you describe them deleting it? I do not believe this is true and you may be misinterpreting something. This has nothing to do with whether or not somebody is observing, it has to do with whether the device is interacting with the electron to determine where it is. The interaction it... | [
"The wikipedia article on ",
"Delayed Choice Quantum Eraser",
" has a bit more information about the erasure aspect:",
"In a quantum eraser experiment, one arranges to detect which one of the slits the photon passes through, but also to construct the experiment in such a way that this information can be \"era... | [
"So it doesn't matter whether or not someone actually observes it, it really matters on whether or not it will be possible for the outcome to be recorded indefinitely? Very intriguing. Now what about the death of the observer? Arguably every person viewing it will die, and the information will be \"deleted.\" What ... |
[
"What causes this colour effect on the rocket engine?"
] | [
false
] | If you watch the engine during firing, there's a band of colour that slowly moves across the rocket bell. Is this the camera or something to do with heating? | [
"Engineer here (who works with video): This effect comes from the camera shutter speed \"beating\" with the lighting (just like beat notes in music, but for video). This is a very common effect. If fluorescent or LED or other non-incandescent lighting is used the light might look continuous to your eye, but is a... | [
"Photographer here: To my eyes it looks like a ",
"moire pattern",
" caused by fine visual details in the bell going in and out of sync with the pixels in the camera's sensor, possibly due to vibrations in the bell and/or the structure housing the bell to which the camera is mounted. "
] | [
"I think you will see it ",
" there during the whole video. At the very beginning, before engine start, you'll see darker/lighter horizontal bands (about 1/3 the length of the nozzle) creeping up the nozzle. Maybe your monitor isn't adjusted to see them on the dark nozzle, so in that case look at the area aroun... |
[
"What role does working memory have in work ethic, taking initiative and career success?"
] | [
false
] | This is in response to seeing the MIT post about intelligence vs. persistence: As I understand it working memory is the attribute by how we retain and manipulate information. Remembering a phone number, retaining what you just read, telling a story without mixing up the sequence, etc… So in a goal for example; How does... | [
"Let's assume that working memory is an observable indicator of the latent factor, \"intelligence\". Along with things like quantitative ability, verbal ability, and spatial ability, memory is going to be higher for those who are smarter. Many suggest the idea of 7 +/- 2 \"chunks\" of information is the typical ran... | [
"I disagree with your point about the relationship between intelligence and motivation. Social cognitive theory (Bandura) would say that motivation largely means self-efficacy, or the belief that one can achieve or be successful at any given undertaking. Self-efficacy mobilizes effort and persistence over time. If ... | [
"Perhaps I can add to this great response with some specifics on the working memory construct. It is worth noting that working memory ",
" attention and specifically we call it \"higher order attention\" (which is different from being-able-to-maintain-focus type of attention). Working memory is intimately tied to... |
[
"Does putting helium into an object (say, a box) make it lighter? Would it weigh less on a scale versus the same box without helium?"
] | [
false
] | The box would somehow be sealed with the helium inside of it. My logic is that you can put helium into a balloon and it rises, therefore it couldn't even be weighed because gravity can never pull it down. If you could put helium into a box, would the helium "pull" the box upward, making the box weigh less? | [
"That completely depends on the size of the box, not the weight.",
"A 5ft cube of air weighs about 10 lb, and the same cube of helium weighs 1.4 lb, so you would see a 8.6 lb decrease, regardless of how much the box weighs. "
] | [
"A box of one cubic meter would be about ",
"1 kg lighter",
" if it was filled with helium instead of air."
] | [
"Well, you're replacing the air inside with helium, which weighs less than normal air. So yes, unless the box previously had a vacuum inside of it."
] |
[
"How can I cheaply cool my room?"
] | [
false
] | null | [
"You can't get much cheaper than subsidized electricity.",
"If the initial cost is prohibitive, find a used one cheap or free on craigslist, freecycle, etc."
] | [
"Put a white sheet over any windows in the room you are trying to keep cool. Keeping sunlight out is the easiest way to keep a room cool. Don't just throw any old sheet over, though. Specifically a white one to REFLECT the light. "
] | [
"Get yourself a cheap window air conditioner for $125.00",
"http://www.amazon.com/Frigidaire-FRA052XT7-000-BTU-Window-Conditioner/dp/B003F4TH6G",
"Depending on the cost of electricity where you live, you should be able to run it for no more than $.10/hour. (500 watts @ $.14 per kilowatt hour = $.07 per hour.)"
... |
[
"Would repetitive consumption of a incredibly hot pepper (Carolina Reaper, etc.) eventually yield lesser physical response?"
] | [
false
] | null | [
"Capsaicin, the spicy component of hot peppers, does indeed cause desensitization of the TRPV1 nociceptor with prolonged activation. This seems to underlie some of the effect of topical capsaicin against several types of neuropathic pain.",
"https://www.ncbi.nlm.nih.gov/pubmed/20932251",
"\n",
"https://www.nc... | [
"To add onto this comment (which explains it very well), this phenomenon is known as receptor desensitization and is part of the reason why returning drug addicts get an overdose. If you do a certain drug (or in OPs case you take a hot pepper) over time your receptors will be desensitized through different mechanis... | [
"To add onto this comment (which explains it very well), this phenomenon is known as receptor desensitization and is part of the reason why returning drug addicts get an overdose. If you do a certain drug (or in OPs case you take a hot pepper) over time your receptors will be desensitized through different mechanis... |
[
"If the Moon gets further away from the Earth every year, is the strength of the tides lessened?"
] | [
false
] | [deleted] | [
"The tidal forces used to be a lot stronger back in the early epochs of our planet's history. snooptray is correct, the tides' strength will lesson over time. I wonder what will happen when we lose them entirely..."
] | [
"That's the idea that some people (like myself) have. What sort of effect will losing the tides have on ocean ecosystems, especially ecosystems that are structured around having nutrients transported by tidal forces? Destruction of those ecosystems could cause a ripple effect."
] | [
"That's the idea that some people (like myself) have. What sort of effect will losing the tides have on ocean ecosystems, especially ecosystems that are structured around having nutrients transported by tidal forces? Destruction of those ecosystems could cause a ripple effect."
] |
[
"What's the consensus (if there is one) on Benjamin Libet's \"readiness potential\" experiments?"
] | [
false
] | I've read many criticisms from philosophers, but haven't found many statements from neuroscientists leaning either way. Is it accepted as fact that decisions are unconsciously made before the agent is aware of it? (There's some info on this here: ) | [
"yes there have been modern updates on this experiment and it is commonly accepted that your brain makes decisions before you are consciously aware of them (and shockingly, sometimes will make up explanations for those decisions after the fact).",
"http://www.nature.com/news/2011/110831/full/477023a.html#B1"
] | [
"interesting idea. does knowing seems to imply conscious awareness? one might argue even a thermostat can make a decision (namely whether to turn the heat on)."
] | [
"correctly, you make your decision before you THINK you are aware of it.",
"if it can be shown that you make your decision before you think you do, why can't it be that you know of your decision before you think you know?"
] |
[
"If pi or other irrational numbers are normal, then can they be used to compress data by referring to where in pi each string of data occurs?"
] | [
false
] | null | [
"No. The value you'd need to point to the sequence would, on average, take up as much space as the sequence itself. ",
"Edit: To the other answers here: Storing 100 bits of random data takes on average about 100 bits. I don't care how fast your computer is or how much time you spend. 100 bits it is. Otherwise you... | [
"That's an interesting idea, but for it to be fruitful you'd need to know infinitely many digits of the normal number. Check out the ",
"Pi-Search",
", where you can search the first 200 million digits of pi. That's a whole lot of digits, but my phone number doesn't appear in them. Neither do the first 8 Fib... | [
"Do you have any idea how long it would take to calculate 200 million digits of pi? probably hours. Also, what is \"constant memory\"? Are you referring to the hard drive or Random Access Memory?"
] |
[
"How analogous to light waves are sound waves?"
] | [
false
] | I've just been wondering this ever since I heard that scientists found out they might use sonic black holes to study how cosmic black holes because. But do light and sound behave similarly enough for this to be viable? | [
"So can sound"
] | [
"We call them phonons."
] | [
"I'm not sure about your sub questions but to take a stab at your primary question: they really aren't that similar. Light waves are transverse waves and sound is usually longitudinal. Sound absolutely requires a medium and light can travel through a vacuum."
] |
[
"Why is the hole in the ozone layer over Antarctica? Why does the ozone not diffuse into an even layer around the Earth?"
] | [
false
] | null | [
"Ozone depletion is due to chlorofluorocarbons (CFCs) in the stratosphere above the Antarctica and to some degree the Arctic. Under the right conditions, CFCs can undergo a reaction that releases chlorine ions, which break up ozone molecules. For a couple of reasons, this is most dramatically observed above Antar... | [
"Here",
" you can see point one demonstrated quite clearly. If you rotate the globe to the north and south poles you can see that at all times there are a ring of weather systems around the south pole, isolating it, while no such thing exists around the north pole."
] | [
"This ",
"Link",
" might show it better (adjusted the settings)"
] |
[
"I was looking around on Google maps and I found some frozen (?) lakes in Russia with periodic lines on them. I'm wondering what those lines are and how they're created"
] | [
false
] | I linked a few examples, though the first one is the most obvious. The first thought that came to me is that, somehow, the waves on the lake managed to freeze, but it doesn't make too much sense when I think about it. The lines themselves follow the same direction in all the bodies of water, which seems strange to me. | [
"pretty sure it has to do with either the watermarking from google, or perhaps the passes the satellite was making to take the pics, they appear on many large bodies of water all over on google maps."
] | [
"If I may ask, why does that mean it is not natural?"
] | [
"That would be a huge formation. Something occurring regularly and at that size would be a very interesting and well studied/documented phenomena. Therefor, if we haven't heard of it and it isn't easy to find information about, it's probably not real."
] |
[
"Do humans use pheromones like animals in ways, e.g., to mark things, for others to detect, etc.?"
] | [
false
] | null | [
"I'm no expert. However, I do remember a lecture on the olfactory system in which my professor spoke of a few studies regarding humans picking up chemosignals. One of them looked at state anxiety of females when exposed to the sweat of males who had high or low state anxiety. The females exposed to the high state a... | [
"Another example is with attraction. People in your reasonably close family smell in a way that stops family members from being attracted to them. Its an evolutionary mechanism to prevent incest."
] | [
"Humans (also) have a organ called, Jacobson's organ, this is a chemoreceptor which detects (or 'senses') pheromones (which in essence are chemicals) secreted by other humans. Humans use pheromones to attract the opposite (or same?) sex. This pheromone gets secreted in sweat. Companies also use pheromones in deodor... |
[
"Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"Are you looking for something like ",
"this map",
"?",
"Units are what I think you are asking about and it does look sufficiently different than the ",
"gravitational anomaly map",
"."
] | [
"The sky is, in fact, blue in all directions, and you can see that fact in ",
"pictures from space",
". ",
"When you're looking up at the sky during the daytime, the background behind the sky is just the blackness of space, so the scattered light in the atmosphere is almost always the brightest thing in your ... | [
"Celestia is great, but I much prefer ",
"SpaceEngine",
". It's a program made by a crazy russian to give ",
"accurate",
" locations of objects that we know about, at any point in time, much like Celestia. BUT, SpaceEngine will randomly generate planets, stars, nebula, and entire galaxies, down to centimete... |
[
"Why does the smell of fast food linger more than the smell of other foods?"
] | [
false
] | Is there a scientific reason as to why the smell of fast food seems to linger longer than the smells from other foods, especially in confined spaces such as airplanes or cars? [edit] Holy cow this blew up much more than I expected, thanks for the informative responses! | [
"It has to do with partitioning. ",
"The way smell works is that a few molecules or tiny droplets of an object (or a volatile component of some substance) takes to the air and a few molecules of it end up in your nose. There, some of it dissolves into the mucous of your nose, and then various receptors recognize ... | [
"Can you please elaborate on this \"bubble of dust\" you speak of?"
] | [
"No, it's a ball of waxy stuff thought to encase foreign objects in the digestive system. It gets excreted and then does float around for years and harden as you describe, but doesn't start out as a liquid. An analogy would be the tonsil stones that sometimes form in the back of your throat from bacteria, food and... |
[
"I have read that phytic acid is responsible for our teeth not being able to regenerate themselves. Is this true? Can teeth heal if allowed to?"
] | [
false
] | There are supposed studies that have been done that indicate that removing phytic acid from the diet, along with introducing a proper balance of nutrients that teeth need to grow, will allow teeth to regenerate. I have to say, the argument is a bit convincing, but I want the trusted people at askscience to weigh in, if... | [
"If that is the case, then it is very likely just a myth made up to make money."
] | [
"That's the thing, they're not selling any products. Sites that claim this just advocate reducing phytic acid intake."
] | [
"Hmm. Still sounds kinda hoaxy."
] |
[
"Why is the definition of mass not \"quantity of matter\"?"
] | [
false
] | I understand the idea of mass and how it comes from the fact that we can apply the same force on different kinds of objects, and those objects will respond differently depending on the nature of those objects. And that the units of mass are essentially arbitrary and refer to the International Protoype Kilogram, which i... | [
"The prototype kilogram isn't meant to be a fundamental definition of mass, but rather something that is easily reproducible (you just need a copy of the brick). You could define a kilogram as a certain number of silicon atoms , but that's harder to reproduce.",
"For most purposes, the mass of an object is just t... | [
"You could define a kilogram as a certain number of silicon atoms , but that's harder to reproduce.",
"In fact, that's exactly what they're doing",
"."
] | [
"I know that GP said it wasn't relevant unless you are dealing with nuclear physics, but I think you will find it is relevant here. The amount of mass something has isn't just a function of how many protons and neutrons it has, but also its energy. Look up something called the \"mass defect\". ",
"Case in point: ... |
[
"Are there any advantages to DNA being a double helix?"
] | [
false
] | null | [
"1)The bases are more protected / less exposed to mutagens on the inside of the helix so less mutation.",
"2) If a base on one strand is mutated then the correct base can be deduced from the base on the opposite strand since they are complementary.",
"3)If replication were to take place using just one strand as... | [
"Ah, thankyou!"
] | [
"in addition, certain mutations and base-pair sequences create shapes in the double helix that can be recognized/repaired by enzymes"
] |
[
"Why does urine form bubbles after peeing in a toilet but water does not?"
] | [
false
] | Is it because of the temperature difference (98.6F vs room temp) between the water and urine, or because of the other contents of urine (urea) creating some sort of odd fluid conditions creating bubbles, or something else? | [
"bubbles are usually caused by soap like molecules. Water from the tap is relatively urine is no where near as pure. If I were to make an educated guess it would be a combination of sugars, water soluble fats and proteins ala desk flyer's link.",
"edit for a slightly longer explaination... Soap molecules have ... | [
"http://www.buzzle.com/articles/bubbles-in-urine.html"
] | [
"Doesn't really answer my question of what causes the bubbles to form, just that being dehydrated or sick can cause excess proteins to build up which form bubbles."
] |
[
"Questions about Quarks"
] | [
false
] | What exactly are quarks? Are they made up of smaller molecules or are they, to our current understanding, the smallest unit of matter? What are strange and charm quarks, and why do they have those names? | [
"Quarks are what protons and neutrons and some other less important things are made of. There is no evidence or other reason to suggest that they are made of anything smaller. Quarks either have plus or minus 1/3 or 2/3 the charge of an electron. The most important quarks are up and down quarks, which protons and n... | [
"To clarify one point, a molecule is a chain/collection of bonded atoms. So no, there are no molecules in a quark. I could go into a little detail on quarks themselves, but I'll leave it to someone with a more comprehensive knowledge!"
] | [
"What exactly are quarks? ",
"They are the elementary fermions which carry strong-force charge (or color charge). This is as opposed to, say, leptons (like the electron) which are the elementary fermions which do ",
" have color charge.",
"Are they made up of smaller molecules or are they, to our current unde... |
[
"You are constantly very very close to biting your own tongue. Why doesn’t it happen more often?"
] | [
false
] | null | [
"Two main factors are at play here. The first is proprioception. The second is pain. ",
"Proprioception is the body's sense of where its parts are located. Meaning even if you close your eyes you know where your arms are. This extends to your tongue, your body tracks it while it's still and when it's moving.... | [
"To add to that, i'd suggest there's also some aspect of design. Whereas we have evolved tongue and teeth placement, size, and position to avoid biting the tongue in the resting state, or by accident in normal chewing or swallowing actions. Even if we do misjudge the tongue is sensitive enough and jaw agile enoug... | [
"Interesting side note here. I remember reading an article at some point in the past about how the game Mirrors Edge was messing with people's proprioception"
] |
[
"Why does human excrement, though often varying in odor due to individual diets, retain such an unpleasant smell?"
] | [
false
] | null | [
"The odor in feces is caused by hydrogen sulfide produced by bacteria in your gut."
] | [
"The answer is complicated, but you may find ",
"this article",
" in the NY Times on \"disgust\" enlightening."
] | [
"It's not so much that hydrogen sulfide smells disgusting by default and vanilla smells nice, but more that we are genetically coded to respond to specifically hydrogen sulfide (and lots of other \"waste\" products) with disgust as it's typically found in stuff that it's evolutionary beneficial to avoid, such as fe... |
[
"Do larger people require more sleep than smaller people?"
] | [
false
] | null | [
"Short sleep duration is associated with just about every obesity measure you can name (BMI, bodyfat%, leptin/ghrelin levels, etc). ",
"Cause and effect are, at this point, strongly favoring that people who CHOOSE to get less sleep cause physiological consequences that make them gain weight. However, I wouldn't ... | [
"What about tall people? Will someone who's 6'5\" require more sleep than someone who's 5'9\", assuming they are both approximately the same BMI?"
] | [
"No tl;dr. ",
"Obese people eat more calories than they burn, period. They were likely obese in development. However, if YOU could control their dietary intake, you could make them thin. No one walked out of internment camps in WWII fat. ",
"Of course, that's rude and insulting, and we don't live in an envi... |
[
"Is there such thing as anti-dark matter?"
] | [
false
] | [deleted] | [
"Nobody knows for sure what dark matter is. One of the most prominent possible candidates is called a WIMP: a Weakly Interacting Massive Particle. A WIMP may be identical to its own anti-particle (like the photon), or it may have an anti-particle that differs in some new kind of charge that is only \"felt\" by othe... | [
"Depends what dark matter turns out to be made of. It's electrically neutral (or else it would interact with light), and anti-particles have the opposite charge of regular particles, and the opposite of zero is zero. However, neutral particles like neutrinos can still have anti-particles with the opposite chirality... | [
"We don't understand enough of \"dark matter\" to even start discussing anti-dark matter. But if it's actually matter composed of particles, then DeBroglie's equation will say that yes there is \"anti-\" Dark matter."
] |
[
"Does Premium Unleaded fuel really clean my engine as advertised?"
] | [
false
] | Hey all I was filling up my car today with standard 91 Octane (Australia) when I started reading the spiel on the pump about premium (98 octane). I am aware of how octane numbers work, and that premium shouldn't offer any mileage benefit to my car as it is designed to run on standard. However, is there any validity in... | [
"There are really two separate issues being conflated here. First is \"engine-cleaning\" fuel additives, second is the fuel's octane rating. The two are independent.",
"Engines with higher compression ratios (high-performance vehicles, basically) have increased risk of having the fuel-air mixture detonate in the ... | [
"The cleaning additives are detergents. Collectively called \"deposit control additives\" or DCA's.",
"What they do is prevent buildup of deposits (carbon compounds) in two critical areas: The fuel injectors, and the intake valves. Injectors have very fine nozzles that atomize gasoline into very fine droplets. If... | [
"What about performance vehicles that \"require\" certain octane levels? Is it really important "
] |
[
"How long does it take from the moment my brain decides to send an action command (moving my arm) to the moment i actually do the action?"
] | [
false
] | null | [
"The electrochemical signal that causes your arm to move happens before we are able to recognize we have made the decision to move our arm. ",
"This has caused some interesting debates on the reality of free-will in neuroscience."
] | [
"The most basic way your brain could 'tell' your muscles to move is through activation of corticospinal neurons in ",
"primary motor cortex",
", which project to ",
"motor neurons",
" in the spinal cord, which in turn activate and cause contraction of opposing groups of muscles. According to ",
"this pap... | [
"The simple answer is at least 10ms since the velocity of the signal along the nerves are around ",
"100m/s",
". The scientific name is ",
"mental chronometry",
" or reaction time and is of 150 to 200ms, but it include the perception time..."
] |
[
"How an SSRI affect your brain?"
] | [
false
] | [deleted] | [
"Hopefully I'm not taking your question too literally, but SSRI = Selective Serotonin Reuptake Inhibitor. Serotonin is a neurotransmitter (one of many) that your brain cells use to communicate (basically, they spit little puffs of it on each other). After the serotonin \"does its job,\" it's taken back up into the ... | [
"Well, there are a number of drugs that are SSRI, so it's more a question of which one you were prescribed rather than what formula the manufacturer used. Some might have less adverse side effects than others for you. But that's something you should discuss with your physician."
] | [
"Fundamental neurochemistry is, relative to other scientific fields regarding the brain and nervous system, quite well researched, however, large-and-broad-scale interactions between chemicals in the brain, groups of neurons, and the ways in which specific chemicals (in this case, SSRIs) act on brain subsystems, to... |
[
"Why do they say that the spin of a pair of entangled particles is not determined until observed?"
] | [
false
] | [deleted] | [
"This is a very common question here. Please read up on ",
"Bell's Theorem",
" and perhaps do a search here in ask science for \"entangled particles\" and then feel free to ask if you have any follow up questions. "
] | [
"I've tried reading bell's theorem before. I find wikipedia can be difficult for things like this, because it can seem as though it is written in a way as to be understood by people that already know what the article is talking about. ",
"I would really like to understand bell's theorem, and how he arrived at it.... | [
"Really? I have yet to find a proper simple explanation for it, though it does seem to be all over the place. Even searched YouTube, found some videos about it, but not really any proper ones. Personally, makes me feel like the moment I grasp the concept, I should make one myself."
] |
[
"Are there \"waves\" on the top of the atmosphere like waves ossn the ocean?"
] | [
false
] | null | [
"Yes, there absolutely are. Any time you have a gravity field and a fluid with different density layers, you can make waves. It gets a little tricky, though, because the atmosphere doesn't really have a top: it just gets thinner and thinner as you go up. And yet, the atmosphere sloshes up and down and back and f... | [
"First, you can have large-scale sloshing motions of the whole planet's atmosphere all together: these are called \"atmospheric tides\", and can be caused by the pull of the Moon or Sun, or by solar heating of the atmosphere.",
"Just to add, we're fairly sure these atmospheric tides and their interaction are what... | [
"But it wouldn't look like a \"wave\"",
"If clouds are present, you very much can see these waves. For example, ",
"this video",
" clearly shows gravity waves in the atmosphere (which are essentially buoyancy waves, and not to be confused with ",
" waves)."
] |
[
"Why does the inverse square law of light (and gravity) happen?"
] | [
false
] | Instinctively I understand THAT light sources get dimmer over distance. But, since light goes on forever unless it runs into something, why in space do light sources appear dimmer over distance and why does it happen according to the inverse square law (as opposed to a linear or other rate)? Also, is this related to ... | [
"Inverse square laws happen a lot with things that spread out over a given area. If you have a light source at the center of a sphere of radius R, then the light is being spread out over an area of 4 pi R",
"; so the intensity goes like 1 / R",
".",
"This happens pretty much anytime that you have a source bei... | [
"To elaborate a bit, it's a result of having three dimensions. If you visualize a field strength as being represented by lines emanating radially from an object, you can see why:",
"In a one-dimensional universe, the density of lines stays the same no matter how far away from the origin you get, because there's o... | [
"... and ",
"My understanding is that string theorists are hoping to find a modification to the inverse square law at short distances as evidence for the \"hidden dimensions\"."
] |
[
"Do all materials release heat when they are elastically deformed like rubber?"
] | [
false
] | When rubber bands are cyclically loaded they release a noticeable amount of heat. Do other materials like steel also release heat when elastically deformed (albeit a much smaller amount)? What about when steel is plastically deformed? | [
"This is not entirely true. When elastically deforming an object, the energy that deforms it becomes the potential energy that will deform it back when you remove the deforming force. In case of steel (say a steel spring) this is stored as strain energy of bonds that hold the crystals of steel together. Elastically... | [
"All solids are technically viscoelastic (meaning they both flow plastically and deform elastically under strain); all of them therefore exhibit some level of heat dissipation under elastic loading. Plasticity is generally facilitated by the movements of dislocations through a structure, which will naturally lead t... | [
"I think the confusion you got is because of the assumptions in my post and on the page you reference. I've said: \"when the band contracts after dissipating the heat produced by stretching it, it becomes colder [than the ambient temperature]\". I've phrased it this way to make it clear that a rubber band can be us... |
[
"Will an immunosuppressant drug allow you to receive an incompatible blood type transfusion?"
] | [
false
] | null | [
"In theory - yes. In practice - this is never going to happen.",
"If a patient needs an urgent blood transfusion, there will not be time to wait for the immunosuppressants to kick in, and anyway the patient will be in too critical a state to also compromise his or her immune system.",
"If the patient does not r... | [
"Immunosuppresents are given to most if not all organ transplant recipients as matching is a lot harder than with just using blood types. Each cell has a marker saying \"this is you\" so your immune system doesn't attack it, when another body part is integrated, these markers aren't the same, and most will never fi... | [
"So I'm guessing they also try to ABO/Rh match patients for HSC transplantation? I know these patients can convert to a new ABO phenotype, do you know if they retain memory for antigens? Do they naturally make antibodies corresponding to their new phenotype? Is it possible that HSCT can cause a primary response to ... |
[
"How do photons exist within an electro-magnetic field?"
] | [
false
] | I have been learning a lot about electro-magnetism recently, and I have tried asking this question to a few people already but none of them seem to know the answer. Do the electric and magnetic fields lines around a magnet mean that that area is filled with photons running along the field lines? Are there photons in EM... | [
"It's absurd to say the EM field is not quantized, since e.g. the loop corrections to the electron magnetic moment, which are an intrinsically quantum phenomenon, have been measured to an extremely high degree of accuracy. ",
" fields are quantized, that's a basic tenet of quantum field theory, of which, say, the... | [
"Yes, disturbing the EM field will cause waves to propagate, so in that case there will be photons, but in the steady case there is a field and no photons."
] | [
"No, photons are quanta of the EM field, the same way gluons are quanta of the gluon field and electrons are quanta of the electron field.",
"They ",
" an energy but that doesn't mean they are quanta ",
" energy."
] |
[
"How fast do radioactive things boil water?"
] | [
false
] | I read somewhere that nuclear power was just using nuclear things to boil water and using the steam to spin a turbine. Is it really that much more effective than burning something else to do the same thing? Also is that the best way to be using nuclear power? I imagined it would have been way more complicated than boil... | [
"I read somewhere that nuclear power was just using nuclear things to boil water and using the steam to spin a turbine.",
"Yes, although \"nuclear things\" doesn't just mean a pile of radioactive material. Inside the core of a fission reactor, there is a self-sustaining chain of neutron-induced fission reactions ... | [
"SPERT",
" - that time the U.S. government and Phillips blew up a purpose-built nuclear reactor in Idaho, featuring terrible 1950s slow motion footage and parts of a nuclear reactor impacting the ceiling of the building. The third version of SPERT (the government didn't stop at one) boiled all the water around th... | [
"Turns out, we are very, very good at turning boiling water into energy with turbines in what’s called the Brayton cycle, sometimes exceeding 50% efficiency. It is possible to do direct thermoelectric conversion, like in RTGs, but that’s inefficient. We also have magnetohydrodynamic generators, which can only do ar... |
[
"Are nuclear weapons test safe?"
] | [
false
] | Why is it that places like Chernobyl and the other plant in Japan are dangerous to visit for prolonged periods of time where as places like Hiroshima, Nagasaki and multiple nuclear test sites are safe to visit? Isn't it technically the same thing, but one is a weapon and the other one is just being used for it energy? ... | [
"Why is it that places like Chernobyl and the other plant in Japan are dangerous to visit for prolonged periods of time where as places like Hiroshima, Nagasaki and multiple nuclear test sites are safe to visit?",
"Atmospheric testing ",
" release fallout into the atmosphere. However since the 1960's or so, mos... | [
"To give an idea of the energies involved: The Hiroshima explosion released an energy of about 60 TJ, that's the power output of a single nuclear reactor block in a few hours. Nuclear reactors run for months without refueling, they need way more material. In addition they don't have to be made as light as possible,... | [
"Atmospheric nuclear weapons tests aren't safe. But that's separate from your question, which is about nuclear fallout.",
"Both nuclear weapons tests and nuclear power accidents release most of their radioactive contamination in the form of fission products, the split pieces of uranium or plutonium atoms. In a re... |
[
"Why do bananas and other fruit rot so much faster when they are in an enclosed space with one another?"
] | [
false
] | null | [
"Ethylene is a fruit hormone that is naturally produced by fruits. When green bananas are kept in a brown paper bag, they will ripen faster!",
"Rotting would be related to the concentration of ethylene in the surrounding gas. Also bacteria that causes rotting can easily proliferate to other fruits when they are k... | [
"To expand on the ethylene thing, ethylene causes fruit ripening, more ethylene makes fruit ripen faster, but it also has a positive feedback loop: the more ethylene there is, the faster more is produced. The ethylene is also released as a gas, so it propagates to adjacent fruit and kick starts ethylene production ... | [
"To expand further, ethylene is a byproduct of incomplete combustion, so if you have a greenhouse, using internal combustion engines inside of it can increase the concentration of ethylene, negatively affecting your plants.",
"More relevant to post-harvest physiology, if someone had a flower or a climacteric frui... |
[
"Do black holes get bigger from absorbing all the light that falls into it?"
] | [
false
] | null | [
"Yes."
] | [
"so do they just keep getting bigger and bigger? is that why there are supermassive blackholes in the center of many galaxies?"
] | [
"Hi magictron thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the follo... |
[
"Is there a method of detecting current in human tissue in 3d space"
] | [
false
] | So, as i pour over ECG's I always wonder, surely there is a better way. I studied most of my physics in the Irish equivalent of high school so its not exactly my strongest subject, but is there a way , theoretically at least, to detect moving changes in membrane voltage of about -70 to + 40 miliVolts running in muscle... | [
"This is how magnetoencephalography works, but the magnetic field involved are really, really small. Like, one trillionth as strong as the Earth's magnetic field."
] | [
"And magnetoencephalography."
] | [
"Another big problem is that the scull sort of blurs all of the signals. "
] |
[
"Would new leaps in protein folding computation produce many non-functional proteins?"
] | [
false
] | In school I learned about how a protein is folded into the native via , but outside of school I learned about how computers are currently incapable of solving protein structure. Then today I watched the that was posted earlier and I learned that the issue with NP problems, such as protein folding, is that you cannot di... | [
"I don't think the P=NP problem really applies to protein folding because the solution to a protein folding problem cannot be checked any more quickly than it can be calculated. ",
"I mean there are obvious cases that can clearly be flagged as wrong, such as impossible bond angles, but they are trivial so we can ... | [
"From my understanding, the researchers that did it dissolved the proteins and then used some kind of mechanical flow to produce the conditions that allowed the protein to re-fold into the native state. ",
"This is similar to something we do in biochem labs when our proteins made from bacteria aren't immediately ... | [
"In practice the models we use effectively check themselves as they calculate because they are iterative models; they check solution n against solution n-1 until the difference is insignificant",
"and",
"different initial parameters",
"answers my question perfectly. Thanks!"
] |
[
"With the exception of therian mammals, did any other clade of synapsids give birth to live young?"
] | [
false
] | Is there any evidence to suggest that other clades of synapsids were viviparous too? Did viviparity arise only once in synapsids? | [
"My guess is that nobody knows because the non-therian synapsids are known only from fossil evidence, often skulls/teeth, and it'd be quite tricky to figure out whether or not a species has viviparity just from the skull and teeth.",
"However viviparity is relatively easy to evolve. Many elasmobranchs have evolv... | [
"The only group of vertebrates that seems to \"have trouble\" evolving viviparity is the birds - some 10,000 species and not a single one of them viviparous - most likely because of flight constraints (pregnant females are heavy). ",
"How about ratites? They arey flightless for quite some time now."
] | [
"My guess is that nobody knows because the non-therian synapsids are known only from fossil evidence, often skulls/teeth, and it'd be quite tricky to figure out whether or not a species has viviparity just from the skull and teeth.",
"However viviparity is relatively easy to evolve. Many elasmobranchs have evolv... |
[
"Since humans are drilling so much oil out of the ground, are there large empty caverns underground where the oil used to be?"
] | [
false
] | Humanity has drilled a lot of oil since the late 1800’s. What happens to all the empty space where the oil used to be? Is it just empty air pockets now or does it fill in with dirt? | [
"Not exactly. The oil is held in rock in the formation, think of squeezing a wet rag with the rag being the formation. The oil goes and formation stays. ",
"Fracturing is the process of opening that rocks natural permeations so the oil, water, and gas can flow out more efficiently. ",
"Of course there may be so... | [
"Not exactly, in the olden days oil would seep out of the ground on its own (even still in places like the tar pits in California), things like salt caverns can hold oil.",
"But I would guess the pictures of the oil shooting out of the ground that your talking about would be after a hole was drilled with the oil ... | [
"Oil is most commonly produced from porous sedimentary rocks. It doesn't come from caverns, but tiny microscopic holes or gaps in the rock. It comes gushing out when we drill through the non-porous rocks above because the fluid is under enormous pressure.",
"The pores are never really emptied, they just stop pr... |
[
"Why is cancer sometimes untreatable?"
] | [
false
] | [deleted] | [
"It can become inoperable by invading deep inside sensitive tissues such as the brain, or by spreading far enough through vital organs so that removing the tumors would kill the patient (such as the lungs or liver). Stage IV means that it has spread to other parts of the body. The majority of chemotherapy drugs don... | [
"We don't know how that has worked, so we cannot say that it is going to work for cancer. There is a hypothesis that the treatment works only in cases with a weak virus or far away from the brain, thus putting the patient in coma slows down the spread of Rabies, giving the immune system more time to fight the disea... | [
"First of all, every medication has something called \"therapeutic range\", which is the range of doses in which it's strong enough to be useful and not so strong that it will serious harm you (or kill you).",
"At some point, every medication is seriously harmful, so if you \"just increase the power\", you will k... |
[
"If an object keeps gaining speed on its way into space will it continue to accelerate within the vaccum of space? If so, for how long? If indefinitely, what happens when it reaches the speed of light? Finally, have we ever recorded or somehow glimpsed a solitary object travelling at the S. O. L.?"
] | [
false
] | null | [
"Massive particles cannot travel at the speed of light. Indefinite acceleration is possible, but the speed will just asymptote to ",
" from below."
] | [
" is the speed of light. "
] | [
"By c do mean the limiting curve? "
] |
[
"are there any statistics on the prevalence of Naegleria fowleri throughout each country and each countries respective case counts?"
] | [
false
] | [deleted] | [
"Probably can’t find stats because the amoeba grows best in warmer waters, hence why it is most prevalent in the southern half of the US. You can probably take an educated guess and say the cases are similar to Minnesota, which has two total ",
"reported cases",
"."
] | [
"We talked about the Minnesota cases on the Halloween episode of the Strange by Nature podcast last year. They tested a number of lakes in the county where a known lake had the amoeba and most of the lakes contained the amoeba. It is probably quite common but rarely causes a problem. You can listen here. It is the ... | [
"This might be more of an epidemiology question and therefore medicine, but I'll give it a shot.",
"I could not find any reported case of primary amoebic meningoencephalitis (PAM) in Canada. Currently it is being ",
"tracked by the CDC",
" within the United States but it appears no other countries are perform... |
[
"Does sunscreen really expire?"
] | [
false
] | All my sunscreen from last year is expired, and that shit is expensive. Does it really expire, or become less effective, with age? | [
"Shelf-life can be a tricky thing to say anything definitive about without knowing how it was set. It could be because the active component oxidizes to a level at which it no longer give the coverage claimed (a performance limit.) ",
"Alternatively, it could be the limited by the active period of a biocide that... | [
"If the active component is TiO2 (titanium dioxide or titanium oxide) then no, it won't go bad. That's rusted titanium, and it photocatalyzes so it protects you from sun."
] | [
"It depends on the ingredients.",
"In a ",
"natural",
" ",
"Zinc oxide",
" based sunscreen, the zinc will never lose effectiveness. However, the vegetable oils will eventually go off and separation may occur.",
"The list of more modern ingredients is large and would be difficult to classify: ",
"http:... |
[
"Why do all domestic cats grow to roughly the same size when domestic dogs can vary in size greatly?"
] | [
false
] | [deleted] | [
"Cat breeds do come in a large variety of sizes, from tiny Munchkins to very large Maine Coons."
] | [
"Dogs were specifically bred to perform certain tasks for people, and as a result physical traits vary greatly between the different breeds. Cats, on the other hand, were not selectively bred for such purposes and so the different breeds look relatively similar."
] | [
"Pretty much. Cats have not been bred for specialized purposes for nearly as long as dogs. Working cats, for example, mainly caught vermin - and they're already the right shape for that. Working dogs could be set to a wider variety of tasks, which called for a variety of body shapes. BIG dogs for guarding, small do... |
[
"Wasn't sure which subreddit to post this in. My right side has been getting weaker but my left has been strengthening."
] | [
false
] | null | [
"I am sorry, but medical advice violates Reddit's Terms of Service so we do not allow it. However if you are wondering what is up you can try contacting a medical professional."
] | [
"I'm not asking for medical advice, I just want to know why this is happening. It's not really bothering me, I haven't even considered going to the doctor about it. "
] | [
"I can understand that. But when asking a medical question about yourself, it is unfortunately considered medical advice."
] |
[
"Pauli's Exclusion Principle - Does It State All Electrons Everywhere Must Occupy Different Energies?"
] | [
false
] | Here in the UK we have a prominent physicist named Brian Cox (who's occupying a similar place as Neil deGrasse Tyson does in the 'States, in terms of public science discussion), who just had a show on TV wherein he explained Pauli thus: That no two electrons can have the same energy, and that as he heated a diamond (by... | [
"No. It says that two identical fermions (like electrons) can't occupy the same energy state. For example, two spin-up electrons can't both be in the 1s orbital (the closest to the nucleus). However, in two adjacent atoms, the electrons in the 1s orbital will both have the same energy, but still not be degenerate b... | [
"I think you are correct. The Pauli exclusion principle isn't even really about energies, it's about quantum states. Two electrons may not occupy the same quantum state, but this isn't the same thing as not having the same energy.",
"I don't know what Cox actually said, but perhaps he was making some big simplifi... | [
"What the Pauli exclusion principle really says is this: the wavefunction describing all of the electrons in the universe must be completely anti-symmetric under exchange of any two electrons in the universe. Luckily, most electrons are pretty non-relativistic and therefore pretty well localized in space. The as io... |
[
"What quantity can be measured most accurately by modern scientific instruments? (e.g. time, heat, number of photons, electrons)"
] | [
false
] | [deleted] | [
"The magnetic moment of the electron can be measured down to the nearest trillionth (it's 2.00231930419922(2) )."
] | [
"And it agrees with theory to 12 decimal places! Quantum Electrodynamics is a force to reckon with."
] | [
"And it's also not the actual magnetic moment, which is the g factor times a bunch of factors of Planck's constant, the electron mass, and its charge, giving about 9x10",
" Joules per Tesla."
] |
[
"When electronics use batteries does the device draw power from each battery equally or one at a time?"
] | [
false
] | null | [
"tl;dr: they draw from all batteries equally the majority of the time.",
"In the vast majority of battery powered electronics the batteries are wired together in series. This means that the positive end of one battery is connected to the negative end of another battery, so the positive end of the first battery a... | [
"Most things will draw from all at the same time. Though whether or not it draws equally from each battery depends on a lot of factors. If they are in series or parallel, if the batteries all have the same capacity, if there’s electronics controlling the power output, just to name a few."
] | [
"I’m not sure for all electronic devices, but some of the radios I have worked with that have 2 lithium Ion batteries use 1 at a time even though the compartment fits two. So you can swap a dead one and keep running the radio on one without losing the programming. The batteries are very heavy so sometime 1 is prefe... |
[
"Is our atmosphere rotating with earth or is it stationary?"
] | [
false
] | null | [
"Look up laminar flow. The air at the surface is spinning with the earth otherwise we would have really strong winds at the surface. In the upper atmosphere it is more spinning less which gives up strong upper atmospheric winds. Remember wind speed is relative to the surface. "
] | [
"Air is a fluid just like water. It sticks to the surface of the Earth. As the Earth rotates it pulls the air. ",
"It's the same idea as water in a glass if you spin the glass the water inside will also begin to rotate with the spin.",
"It's also the same idea as an uncooked egg. Spin the egg and the fluid insi... | [
"It's almost exactly rotating with the earth. Some parts of it rotate a little faster, some a little bit slower: from our perspective moving with the Earth, we see the difference as an eastward or westward wind. But the difference in rotational speed is generally less than 5-10%."
] |
[
"What exactly was Schrodinger trying to prove with “Schrodingers Cat”?"
] | [
false
] | null | [
"Schrödinger proposed the cat thought experiment to illustrate the ",
" with the Copenhagen interpretation of quantum mechanics. It was meant as a ",
", an argument that shows that if you take a train of logic too far, you get silly results. Specifically, the idea of quantum superposition being related to obse... | [
"In the Schrödinger equation, you have various terms that describe the property of a quantum system. In some cases there is a possibility that the information about the system is not known — e.g., an electron might have spin-up, or it might have spin-down (spin is a quantum property; you don't have to understand wh... | [
"Excellent response! If you don’t mind me probing further, what is a “quantum superposition”?",
"ELI5 ideally :P"
] |
[
"How can a doctor check for HIV with a cheek swab if kissing someone with AIDS won't cause me to get AIDS?"
] | [
false
] | null | [
"First of all HIV is generally quite fragile, so often it will happen that it simply disintegrates before it can reach a suitable host cell. Furthermore it needs to be properly assembled to be infectious, which is not always the case. Even if it reaches a suitable host cell, the insertion of it's RNA may fail or th... | [
"To elaborate a little, there is little to no virus in the saliva or epithelial tissue of your cheek. There may or may not be cells present nearby that have been infected by the virus, but they will be rare, since only specific immune cells can be infected by HIV. These infected cells will contain a copy of the HIV... | [
"The posts here are not entirely correct. Most buccal swabs are checking for the antibodies your immune system makes against HIV. They are not testing for the virus directly.",
"What the other posts have correct is that there is little to no HIV virus in the oral cavity, unless of course you have an open wound pr... |
[
"Unknown black dot on Jupiter"
] | [
false
] | I was just out tonight with my 10" LX-200 taking pictures of Jupiter using an Orion Starshoot 3MP LPI, and when I went in to process using Registax 6 i noticed a black dot just south of the Great Red Spot. At first I thought it was a transiting moon, I recently saw Io midtransit, then I checked my starmap app and I co... | [
"Given that you have the data for the moons, is it possible that while none are actively transiting, you could be seeing a shadow from one of the moons? ",
"Since from the picture I can't make out the direction of the sun I don't know if that is possible or not. But seems like it could either be a impact or a sha... | [
"Here is his image",
"-helpful AskScience mod who knows little about Astro-stuff."
] | [
"Yep, Europa's shadow. See my other post for explanation, and ",
"here's my re-creation of this shot.",
" (Callisto is off-screen to the right)."
] |
[
"Can a magnet orbit another magnet?"
] | [
false
] | null | [
"It is at least plausible. One situation: one heave magnet rotates about it's center of mass, the other magnet orbits and rotates such that the force between the two are constant.",
"Basically, they rotate in such a way that they are tidally locked.",
"However, this will create em radiation, so it will not be a... | [
"While this could happen from a mathematical standpoint, it would not be a stable system, unlike gravitationally bound orbits. The polarity of the field would result in a total collapse of the orbit under small perturbations."
] | [
"If you tilt one of the magnets a tiny bit, the system won't move back towards a stable orbit, unlike if you put a rocket on the moon and pushed it towards the earth."
] |
[
"What is the most environmentally friendly way of disposing of the dead?"
] | [
false
] | What method of disposal for our dead bodies would be "greenest". Pick from the traditional types or make your own! | [
"sky burial"
] | [
"Alkaline hydrolysis",
" is claimed by its creators to be better than burial and cremation."
] | [
"Link",
" for the curious."
] |
[
"Why was I born with blonde hair that fell out and then came in brunette?"
] | [
false
] | I stole a stack of "baby books" from my parents earlier this year and have been making a slideshow for them for Christmas. (Worry not, Reddit, it will be delivered with a box of tissues.) While scanning photos I was reminded that I was blonde-haired until I was about 5 years old, and then it all fell out and came in br... | [
"Everyone: This question is not asking if you have had the same thing happen to you, it is asking for an explanation. Please don't add your personal experiences here. "
] | [
"In the hair follicles an organelle named the melanocyte can make three types of melanin pigments: brown eumelanin, black eumelanin and pheomelanin (red). Melanosomes are organelles that can be moved",
"At birth brown eumelanin and pheomelanin are the predominant pigments produced by Caucasians and are present in... | [
"Unless your population is all white, you are probably wrong."
] |
[
"What's the difference between the claim that asteroid collisions were the source of Earth's water, and a theory that Earth's water has been present from its accretion?"
] | [
false
] | contains the following sentence: "The water vapor emissions from the comet are significantly different from the stores on our planet, suggesting that asteroids, not comets, may have been the main source of Earth’s water." When Earth initially come into existence, wasn't it because of the mutual attraction, collision, a... | [
"Or is there some reason to think that A) our water was delivered some significant amount of time after the rocky part of our planet formed, and B) the asteroids that delivered it (if that's what happened) were categorically different in some way than all of the asteroids that eventually became Earth?",
"Yes, thi... | [
"Wow, thanks for the detailed response! So if I understand correctly, the answer to my question is that depending on how much if the excess deuterium to protium we can account for by atmospheric escape, it's possible that most of our water was here from the start; otherwise some of it had to come from either comets... | [
"Yep, you've got the basic idea. The point of the article you linked to is that we had certain ideas about what the deuterium fraction should be for comets, but our direct measurement for this one comet doesn't seem to line up perfectly with our estimates, and so we may need to look elsewhere for this reservoir of ... |
[
"How does an instant cold pack work?"
] | [
false
] | As per wikipedia: I understand that there is an endothermic reaction that absorbs heat energy from the surroundings, which is then stored in the chemical structure of the reactants. So if you put a pack on your leg, your leg provides heat energy that drives the endothermic reaction. What happens if you put the cold pac... | [
"No. Take the cold pack as a closed system consisting of a tube of NH4NO3 and a bit of H2O. The NH4+ is bonded to NO3-. When it comes in contact with the water energy from the water, in the form of heat, goes into the bond and breaks it. It takes energy to break bonds, and energy is released when making bonds. The ... | [
"In the broadest sense yes, but you wouldn't be cycling anything.This reaction in particular would require a whole lot of reagent and a constant supply of clean water. It would produce a lot of waste, but I guess you could refrigerate things like this if you had to. There are lots more ways to cool things that are ... | [
"Thanks for re-reading the question.",
"So in a closed system at thermal equilibrium, the water in the cold pack will lose heat; this would create a thermal gradient, which in turn will cause some convection flows in the air around the pack. There is no energy being put into the system, so wouldn't this break the... |
[
"How bad is the space junk problem?"
] | [
false
] | Was just watching Gravity with my friend and we started talking about space junk, the old satellites and debris floating around up there at astronomical speeds, and were wondering how bad it actually is. Has it ever interfered with a mission to outer space? Is it a legitimate worry our astronauts have to account for? | [
"For a scintillating read a few times a year, I recommend ",
"Orbital Debris Quarterly",
".",
"In brief summary -- yes, it is a significant problem, and the US government spends significant resources tracking as much debris as possible, partly in order to be able to move spacecraft out of the way when the sit... | [
"Plans? Yes. Possible with current technology? Not exactly.",
"Currently we can manually (launch a ship up, grab it or put assist rockets on it, then bring it down) bring down the largest debris. But they are in the minority when it comes to the amount of debris up there. Most of it is tiny stuff, hammer sized an... | [
"This is a very good question that unfortunately has no clear cut answer. There are satellites falling to Earth all the time yet most end up burning up in the atmosphere upon re-entry. Also one thing Gravity does get wrong is that everything is kept at the same 'height' from the top of the atmosphere and everything... |
[
"Why doesn't the body break down drugs like caffeine during digestion before they reach the blood stream?"
] | [
false
] | null | [
"Two reasons: ",
"I'll use caffeine as the example, per your request. Caffeine is absorbed into the blood stream from your mouth, throat, stomach, and intestines. This absorption happens rapidly as you drink a cup of coffee for example, since caffeine is both water- and lipid-soluble. So, it gets into the blood s... | [
"Yep, also important to note is that caffeine is stable at low pH and won't be degraded in the stomach."
] | [
"Short answer? Digestion doesn't deal with metabolising drugs. The liver does that.",
"Your digestive tract isn't there to metabolize your food. it digests it-- beating the complex tissues down into easily aborted and utilized sugars, amino acids, etc. Using acids and reactive lytic enzymes.",
"Now, when that ... |
[
"What exactly is happening in an automatic gearbox when a car is at a full stop?"
] | [
false
] | The output shaft is constantly spinning when in drive, even at a stop, so what stops the engine from stalling? | [
"Expanding on this... for a simple visual imagine two fans sitting facing each other. Turn one fan on and it'll blow air against the other fan's blades and cause that fan to turn. In the torque converter one fan is blowing fluid at the other fan to cause it to turn. When the vehicle is stopped the force from the br... | [
"instead of a clutch, there's a torque convertor...which is two plates (one on the input, and one on the output shaft) in a pool of a non-newtonian fluid that becomes more viscous with shearing force.",
"at an idle, there is very little force, so the shafts are effectively decoupled. when you accelerate, the inpu... | [
"in a pool of a non-newtonian fluid that becomes more viscous with shearing force.",
"I don't think this is correct. The torque convertor really has two parts connected by the fluid. But the fluid does not need to be nonnewtonian. The fluid is spinned by the blades on input sides and forced to the blades on the o... |
[
"How would you ground electronics in the space station?"
] | [
false
] | Ha! There is no ground. Jokes on you. Seriously though... how does that work. | [
"There is a defined 'ground' on any spacecraft. Normally you use the main structure, but it can be different. Obviously this ground will not be at 0V compared to the actual ground (which isn't chargeless anyway), but as long as everything is coupled to the same 'ground', it's fine, since voltages are potential ",
... | [
"The typical problem on spacecraft is where an instrument accidentally hooks a signal varying path directly onto ground, which then introduces noise into all the other instruments that are tied to the same ground."
] | [
"The typical problem on spacecraft is where an instrument accidentally hooks a signal varying path directly onto ground, which then introduces noise into all the other instruments that are tied to the same ground."
] |
[
"Why is it that the de facto standard for the smallest addressable unit of memory (byte) to be 8 bits?"
] | [
false
] | Is there any efficiency reasons behind the computability of an 8 bits byte versus, for example, 4 bits? Or is it for structural reasons behind the hardware? Is there any argument to be made for, or against, the 8 bit byte? | [
"People should know, \"word size\" is a term of art in computing. It's more or less the smallest number of bits that needs to be loaded in order to read one bit. So if your word size is 32 bits, you have to load all 32-bits of a word if you want to know what the last 4 bits say. "
] | [
"There really isn't a definitive reason. There were other architectures that had different data unit structures but because of marketing or user friendliness or whatever reason, systems that used 8 bits won out and became standard.",
"At the time 8 bits was convenient because using binary to interpret them it pr... | [
"What exactly defines a \"word\" isn't defined perfectly, but I think the definition of \"smallest chunk of memory that can be involved in memory transfers\" is much less common than \"the size of a GP register\". I can't remember the last time I worked on an architecture that only had word stores and loads. Most a... |
[
"What makes a room \"stuffy\"? Heat? Humidity? Scent?"
] | [
false
] | [deleted] | [
"All of em'. The humidity can affect how potent certain smells (like dried milk on the carpet) are in the room, and the size of the room makes a difference as well. It can be as hot in my living room as it is in my bedroom, but my bedroom feels more stuffy. ",
"Might also have to do with dust in the air."
] | [
"One of the biggest factors is whether or not there is air cycling through the room. The air would become saturated with CO2 if it was a room with no air flow which gives room air that heavy, \"stuffy\" feeling you mentioned. With cycling air, there is a higher oxygen/C02 ratio"
] | [
"I appreciate the response. Once I started thinking about this it made a lot of sense intuitively, but that's not always proof.",
"a) A hotter room will have less air in it due to expansion. Could explain why cold rooms are rarely stuffy.",
"\nb) A closed door will help trap C02 in.",
"\nc) As a room's oxygen... |
[
"[Biology] How can RBCs function without a nucleus?"
] | [
false
] | I understand that they don't reproduce from a mature RBC, but how are proteins replaced in RBCs? | [
"The proteins aren't replaced. This is why RBCs have such a high turnover, they have no mechanism for cellular repair"
] | [
"No apoptosis necessary without a nucleus. They're snagged by the spleen."
] | [
"When RBCs get old, they become less flexible and have a hard time squeezing through capillaries. When this happens, the old RBCs get caught in the spleen and eaten by macrophages."
] |
[
"What's the difference between sentience and consciousness?"
] | [
false
] | null | [
"Do you mean sapience? Sentience has to do with experiencing pain and other emotions. For instance, we know beyond doubt that dogs, cows, birds, lizards, etc. have emotions and are sentient. Sapience is the question of human level cognition, awareness of self and higher decision making. I think there's a good chanc... | [
"Seems to me like there are two angles you can look at this from.",
"1: Does an organism become conscious before they become sentient?\nWould the difference here be that a being who is sentient is aware of their own consciousness?",
"2: I am sentient and conscious. If I get knocked out I am now sentient and unc... | [
"Is there growing (though not completely conclusive) evidence of the sapience of any non-human species?"
] |
[
"Why do we believe gasses compress to form stars?"
] | [
false
] | I’m not challenging that, but I just want to know the logic that went into forming that hypothesis so I can better understand how it all works. ~ Thanks! | [
"So the important force here is gravity, coupled with the idea that the universe in not homogeneous (the same every where).",
"So the argument is as follows:\nImagine a small box with a uniform density/distribution of hydrogen (let's ignore the edges for now)\nIf we wait for a long time nothing would happen as th... | [
"Thank you so much! This was a stellar explanation! ",
"I like your box example, it really helped me put the “gravity cloud” into perspective."
] | [
"So the energy is actually the energy of the big bang. The big bang essentially pulled everything that's trying to pull itself together apart. The energy is then left in the potential energy of the gravity. Gravity is a force converting this potential energy back to kinetic as it moves towards the centre of a soon... |
[
"Why are chickens, pigs, and cows so widely used for food throughout the world?"
] | [
false
] | These aren't the healthiest animals to eat and they consume a lot of resources to reach the stage where they can be killed for meat - why eat them so much? | [
"These aren't the healthiest animals to eat ",
"Only because we've bred then to be fatty and grow as quickly as possible.",
"and they consume a lot of resources to reach the stage where they can be killed for meat ",
"Actually, chickens and cows are killed relatively young. Cows after a couple years, and chic... | [
"When speaking of diverse small to mid size farms, the answer would be synergy. In general, animals are a sustainable protein source producing fertilizer for the vegetables. Win/win for any farm. These particular animals each have an exclusive benefit they provide farmers over similar protein sources.",
"As far a... | [
"you can feed them literally anything."
] |
[
"Why are we not blinded by the froth of virtual photons interacting with our retina?"
] | [
false
] | Or alternatively, do virtual photons not interact with anything? | [
"If it's alright, I'll copy my answer about virtual particles from here:",
"http://www.reddit.com/r/askscience/comments/gznrr/can_someone_explain_how_virtual_particles_carry/",
"\"In the usual picture, when two particles interact electromagnetically (for example), a photon goes between them as part of the elect... | [
"That's not always the case, though. Virtual particles \"becoming real\" is how black holes are theorized to \"evaporate\".",
"No... it's not. That explanation for Hawking radiation is yet another example of how virtual particles are a very useful way of picturing things (in either the original black hole radiati... | [
"Another way to think of this: mass/energy can't be created or destroyed. If virtual particles popped into existence and then interacted with your retinas, there would be a net gain in total energy, which would violate the conservation law.",
"That's not always the case, though. Virtual particles \"becoming real\... |
[
"Can bacteria take over cells like viruses do?"
] | [
false
] | [deleted] | [
"As other comments explain well, viruses have no way of reproducing ",
" by using the replication machinery present inside a living cell, but bacteria are cellular entities that have everything they need to replicate already. That said, there are some bacteria whose life cycle involves invading the cells of thei... | [
" viruses inject their genetic material into a host cell, that then creates more copies of the virus. That is what viruses do, that is what defines a virus. A virus itself is not in the classical sense alive. It has no metabolism, it cannot replicate on its own.",
"Basically what a virus truly is, is just some fo... | [
"I just think it's curious that all excelente replies forgot to mention that the mitochondria inside your cells were, a long time ago, a free living bacteria! Most of its genome is now on the host cell nucleus. If it is not \"taking over\" on steroids..."
] |
[
"Does alcohol cause dementia? Are there studies done on this?"
] | [
false
] | null | [
"clarity nitpick: there are no \"benefits\" to alcohol in terms of health. All of us who drink are choosing to poison ourselves because we like the side-effects. Obviously that's a trade-off the majority of people are happy with, but I wouldn't want anyone to think that a small amount of alcohol is beneficial to ... | [
"A quick search shows ",
"this article on the UK Alzheimer's Society",
" regarding alcoholism-related 'dementia'.",
"They use quotations around dementia because it is not exactly the same issue, it is really dementia-like brain damage that results in focus issues, problem solving impairment, poor emotional co... | [
"There have been a lot of studies back and forth over the years, the difficulty being that non-drinkers are (in Western nations) are a weird group including a disproportionate number of former alcoholics and those with nasty conditions that make drinking dangerous for them. Therefore non-drinkers tend to look unfa... |
[
"What physical characteristic allows gold/silver coins to \"ping\"/resonate when struck while coins made from other metals with the same crystal structure do not?"
] | [
false
] | For example a platinum coin does not resonate when struck, even though it has the same face-centered cubic crystal structure as silver and gold. Does the speed of sound in the material play a role? | [
"It more has to do with the harmonic frequencies that resonate in the metal that make the ping. This is how a tuning fork works but in the case of the platinum I would guess that the harmonic that it reaches produces a sound that has too small of a wavelength for a person to hear which really has to do with the sub... | [
"Yes, depending on how big you make it. f =c/2L, where f is the frequency of the first harmonic, c the speed of sound in your material and L the diameter of your disc."
] | [
"Does this mean if there was a larger platinum disc being struck it would likely ring?"
] |
[
"Can a moon orbit 2 planets in a figure 8 style?"
] | [
false
] | null | [
"No, because the two planets must be orbiting something as well. If they are isolated in space then they are orbiting eachother, and you have what is called a \"3 body problem\". If the two planets are orbiting a third planet or star, then you have a \"4 body problem\". ",
"Things get increasingly difficult wh... | [
"Thanks! The three body simulation at the end there is pretty close to what imagined might happen. Couple of questions:",
"1) since the center of gravity appears to be the center of the three body figure eight, couldn't that entire system orbit a much larger star?",
"2) in the three body simulation, if two of t... | [
"3+ body problems are excellent examples of \"chaos theory\" in action. Aka. sensitive dependence on initial conditions. ",
"I am afraid I cannot answer those questions without running a full simulation of the initial conditions. There is simply no way for me to tell you what will happen when the situation is ... |
[
"Is time just the way we measure how long gravity is taking to pull us toward whatever it is pulling us towards?"
] | [
false
] | It seems like time/gravity are intertwined but if we can see light from the past, which is a measurement of time, is this only because gravity has an effect on light? I just keep coming back to time/gravity and feel I dont know enough about their relationship. | [
"No, because even in the absence of gravitation, time is a meaningful concept in special relativity. Time and gravity do share a relationship through curvature, but in the same way space shares a relationship with gravity which is part of the reason why we call it spacetime. Gravity ",
" any distortion of spaceti... | [
"I just want to add a slight clarification here. You could do exactly the same with the Schrodinger equation. A nice easy review (mainly about the ADM decomposition but they talk about the vanishing hamiltonian as part of that) is written ",
"here",
".",
"The point is that if your time coordinate is an arbitr... | [
"the truth is that time does not exist, it's merely space that's warping",
"Relativity would like to seriously disagree with you. The metric tensor explicitly places time and space on equal footing which is more generally referred to as a unified framework called spacetime. Time warping is supremely important to ... |
[
"Is the 'explosion' part of a nuclear explosion just what happens when something gets very hot, very quickly?"
] | [
false
] | Is a nuclear explosion just what happens when a chunk of metal is nearly instantaneously heated to around 100,000,000 degrees in our atmosphere? Or put another way, If I suddenly had the power to heat an object, let's say the cast iron pan sitting on my stove top, to 100,000,000 degrees very, very, very quickly, how cl... | [
"No, the energy released in a nuclear explosion is orders of magnitude more than the energy stored in a few kilograms of very hot iron (which at that temperature would be a plasma). ",
"I don't know exactly what what would happen with the iron, I guess you would get an explosion of some kind as it super heats the... | [
"The temperature spiking is simply a side effect of the massive amounts of energy released. For example, the fireball of a nuclear detonation tends to be caused by soft x-rays interacting with the atmosphere, dumping a lot of energy which causes the air to heat up. But of course a wide range of electromagnetic freq... | [
"So what is the nuclear chain reaction doing besides heating up the material of the bomb to ~100,000,000 degrees? Can't the energy released by the runaway fission just be represented as a massive increase in temperature?"
] |
[
"How can something be transparant?"
] | [
false
] | Air is all around us, and we can "see" glass, but how is it possible for something to be composed of matter yet still be transparant? | [
"There's a lot of misconception on this issue. Actually, it all comes down to the photon's ability to excite the electrons of the substance. If the energy required to excite an electron is higher than what the photon can provide, it cannot be absorbed and therefore passes through.",
"This video by SixtySymbols ex... | [
"Glass isn't transparent, at least to understand why photons or light can pass through glass let's define what transparent will mean to the answer.",
"The reason I bring this up, is when we use the words transparent, translusent or opaque we are talking about a materials properties towards the visible spectrum. T... | [
"oh"
] |
[
"In the math world, what's so important about proving the Clay Millennium problems? What will proving them change?"
] | [
false
] | If you only know about one or two of them, by all means explain what you know. Be as technical as you want. | [
"Just having proofs of them is not particularly world-changing. It's the math that will be invented to solve them that are invaluable. For each of those problems, we have an expected answer, but no clue how to go about solving them so the proof will more than likely lead to new branches of math. ",
"We've seen th... | [
"Math provides us with tools. When Einstein thought about the elevator problem and realized that gravity is indistinguishable from acceleration, it allowed him think about space and time differently, as a curvy surface. Luckily decades before Gauss, Riemann, and many others figured out the mathematical tools to dea... | [
"In situations like that, where a physicist has a qualitative idea for how something might work, how does s/he go about finding (e.g.) manifolds to describe it?"
] |
[
"After the Human/chimpanzee divergence, was inbreeding required?"
] | [
false
] | Im aware that humans have 23 pairs of chromosomes, and chimpanzees have 24. There became a divergence when there was a chromosome fusion. Since that fusion had to have been a rare mutation, wouldnt there have to be some kind of inbreeding? Or were the ones with the chromosome shift able to still reproduce with the c... | [
"The first pre-human who had the fused chromosome mutation would have had reduced fertility with the other members of its species who still had 24 chromosome pairs, but it wasn't a complete barrier to reproduction.",
"If it were then that individual would never have been able to reproduce.",
"They would have ha... | [
"You didn't answer the question and it was also pretty clear that the person who asked the question already understood people didn't spring from chimps, since they specifically asked about divergence."
] | [
"First, humans didn't spring out of what we call chimpanzees. The common ancestor population of humans and chimpanzees most likely experienced some sort of division leading to two different populations which evolved separately. One population was prehuman, the other was prechimp."
] |
[
"What exactly is electron spin?"
] | [
false
] | Often when reading about atoms and atomics orbitals the topic of spin comes up. I understand some of the basic college level ideas about spin, but often times both in my chemistry classes and just reading around people include the caveat that the electrons are not in fact spinning, and that "spin" is just a useful plac... | [
"It's intrinsic internal angular momentum. Let's take that in two pieces. Intrinsic: it is a property of the particle, not anything of the particle's interaction with its environment. Internal angular momentum: it's an angular momentum that ",
" come from the particle orbiting something. It's something internal t... | [
"The problem with electrons is that it ",
" really take a lot of rigorous math and physics to properly describe them (as we currently describe them.) ",
"I like your answer, though."
] | [
"A good way of thinking about the concept of spin is by an analogy. Let's imagine you live in a universe where there are no potentials (gravitational potential, electric potential, etc) at all. This would mean the only form of energy you can have is kinetic energy. So you'd have a law called \"conservation of energ... |
[
"When they found out that hubble was near sighted, how did they know how to perfectly shape the corrective mirrors?"
] | [
false
] | null | [
"In optics there is a term called the point spread function. This is what happens when you give an optical system a single point (like a star) as an input, and look at the output on the other side. Ideally, you will get a single point on the output, but in a non-ideal system (like the flawed-Hubble) you'll get so... | [
"In addition to the other answers, ",
"here",
" is the original paper where the commission to determine the nature and extent of the aberration presented their results. In addition to analyzing the Hubble imagery, they also investigated the mirror grinding machine's settings, and created models of their hypothe... | [
"Apparently, no one reads the newspapers, which readily confirm what I said. Here's one article:",
"http://content.usatoday.com/communities/sciencefair/post/2012/06/nasa-receives-two-hubble-class-space-telescopes-from-spy-agency/1"
] |
[
"What forms of energy does a computer output? Does it all translate into thermal energy eventually?"
] | [
false
] | [deleted] | [
"Substantially all the power your computer consumes is converted to heat, mostly on the circuits, some as sound (which hits the walls and ends up as heat) and the light which is absorbed by the walls. (I assume no windows here).",
"A very small amount of energy would be lost through EM fields. You would need pret... | [
"People are weird about things like this. Mind you, your father might have been right during cooling season or during the times of the year you didn't need to run the heater. ",
"Funny thing about electric heaters: they are all 100% efficient. Some might be quieter than others but they are all 100% efficient. And... | [
"People are weird about things like this. Mind you, your father might have been right during cooling season or during the times of the year you didn't need to run the heater. ",
"Funny thing about electric heaters: they are all 100% efficient. Some might be quieter than others but they are all 100% efficient. And... |
[
"Collecting Lunar Regolith with magnetic hoses."
] | [
false
] | I just found article and was wondering if it is even feasible. Basically, they want to create a hose with electromagnetic rings running down the length of it to vacuum up regolith. I realize you can pulse the rings in a cascade so the regolith is brought up the tube, but does the regolith have enough charge to be affec... | [
"This sounds a little fishy to me. The moon is chemically differentiated -- the lighter elements are near the surface and the iron is presumably in the core. Though the regolith is made of lunar material and impact material mixed up, I question how much of this regolith is ferromagnetic."
] | [
"There is ",
"this",
" on wikipedia. I guess gamma rays and such are powerful enough to ionize the smaller particles. Still, I think you are correct. Most of the regolith wouldn’t be affected by the magnetic field."
] | [
"Yeah, that's only very small particles, not significant amounts of regolith capable of building structures with."
] |
[
"Why don't you get infected when you wipe too hard and there's blood on the toilet paper?"
] | [
false
] | Logically it should be like rubbing faeces in an open wound, but it doesn't seem to pose a big problem. Why don't all the pathogens which can cause disease get into the bloodstream and if so, why don't they effect us as much as they would elsewhere? | [
"Also, you don't get blood on toilet paper from wiping too hard. You probably have a hemorrhoid.",
"The rest of your post is good. That part is nonsense though. A small dab of light red blood certainly does not indicate hemmorrhoids...."
] | [
"About 10% of the time you have a bowel movement and often when you floss your teeth you get a transient bacteraemia, i.e. bacteria circulating in your blood. Your immune system manages to clear them which is why we don't all die of sepsis. "
] | [
"A small dab of light red blood certainly does not indicate hemorrhoids....",
"No, it really does. A small dab of light red blood indicates a scratch or abrasion of some kind, and if it's on a blood vessel then that's called a hemorrhoids.",
"If it's not on a blood vessel, then it's called an anal fissure, whic... |
[
"Why is silver a bad catalyst, except for oxidation reactions?"
] | [
false
] | [deleted] | [
"I'm not really sure what you mean by \"sticky\". Silver is great at catalyzing redox reactions because its +1 oxidation state has a very strong driving force to become reduced to the zero valent state (Ag metal). One important feature of many catalysts is their ability to access several different oxidation state... | [
"That, and it forms quasi-stable oxo compounds."
] | [
"(Yay, a catalysis question!)",
"Silver is an epoxidation catalyst used in industrial applications to make the very important chemical ",
"ethylene oxide",
". It is an intermediate for many chemicals in the manufacturing process. It is used for the direct epoxidation of ethylene to ethylene oxide. A single ox... |
[
"Is it unrealistic to assume all intelligent life would be humanoid?"
] | [
false
] | You see in almost all scifi that intelligent life is bipedal with arms with dexterous hands, a head, etc. It seems like life could be in all shapes and sized, but so far, the things that make us humanoid are also what makes us intelligent life. Is there any truth to that, or are there theories to the contrary? Thanks! | [
"If by \"intelligent life\" you're demarcating at \"building technologies\" and so on, then yes, it's very unrealistic. It is useful to have dexterous limbs, but that doesn't necessitate hands--just look at this ",
"elephant painting a picture",
". Tentacles and other ",
"muscular hydrostats",
" make for gr... | [
"By intelligent life, I did mean being able to build technologies, and develop the required space travel to find and interact with us on earth.",
"Would muscular hydrostats be good at making tools if you only had one (like a tongue) or would you need two or more (like boneless arms and fingers)? Also, the elephan... | [
"Elephants aren't known to do stuff like that in the wild, but when they were shown what the brushes did (someone just dabbed one in some paint and dragged it across a canvas idly), they spontaneously started painting without being shown what to paint or anything like that. ",
"A single appendage is probably insu... |
[
"At what ABV% does an alcoholic drink become dehydrating instead of hydrating?"
] | [
false
] | I've read that older civilizations would drink beer instead of water throughout the day, but because it was lower in alcohol content than modern beers, it wasn't really intoxicating and didn't result in being dehydrated instead of hydrated. Is there a flipping point for the alcohol content when it stops hydrating a per... | [
"Disclaimer: while I do have flair, my field of study is not related to health or biology. Take this answer as if it was from a non-flaired user.",
"The idea that people used to drink beer instead of water is not rock solid from a historical standpoint, and doesn't really work out from a health perspective.",
"... | [
"This doesn't give us the answer we really want, as it suggests that even a drop of alcohol in a bucket of water converts it to non-hydrating. Alcohol may stimulate free water loss, but what we care about is NET hydration. If a liter of weak beer is mostly water and stimulates loss of 100 mL, that's fine."
] | [
"Would this in turn mean that drinking beer instead of water and dry foods will kill you quite quickly?"
] |
[
"Was calculus discovered or invented?"
] | [
false
] | When Issac Newton laid down the principles for what would be known as calculus, was it more like the process of discovery, where already existing principles were explained in a manner that humans could understand and manipulate, or was it more like the process of invention, where he was creating a set internally consis... | [
"As others have said, this question is very philosophical in nature, but I'll add to that a bit, making it as simple as I can.",
"When it comes to the nature of mathematics, there are two ",
" views:",
"1.) ",
" - this is essentially the idea that mathematical objects are \"real\" - that they exist abstrac... | [
"That's a question of a pretty philosophical nature, so it's hard to say how well it can be answered. That said, mathematicians typically talk in terms of \"discovering\" a proof or method, thinking of the process as finding a principle hidden in the laws of math that they can now use to their advantage. As far as ... | [
"In one sentence: calculus is the study of rates of change.",
"With algebra you can plot the position of an item over time and try to find a model for it. With calculus you can find the velocity, the acceleration, and the total distance traveled all as functions."
] |
[
"Optically active substances: How do they work? [more specific question in text]"
] | [
false
] | Optically active substances take polarized light and change it's plane of polarization. Why is the effect cumulative when shining polarized light through a volume of the substance (i.e. why are the changes in polarization different when you shine the light through different concentrations or volumes of the material). D... | [
"Optically active substances have different indices of of refraction in the X and Y plane. The wavelength of light is related to the index of refraction. So, as light enters the substance, the X and Y component of the light each experience a different index of refraction, speed, and wavelength. It is this differ... | [
"Woah. Thanks. and about my other questions about commutativity and cumulative result of repeated changes in the plane of polarization in optically active substances. It may have been answered already. I was just thinking, how does this work in the context of say, a single fructose molecule vs, a solution of lots o... | [
"Solutions, or liquids in general, will tend to be arranged randomly, so you won't get a different index of refraction along the different axes. ",
"In general, the index of refraction is more of an aggregate effect than something that happens on a molecular level. Certainly an individual molecule would lack the ... |
[
"Why does a french horn need valves?"
] | [
false
] | If the french horn pitch can be controlled by producing a faster or slower "buzz" with the lips, why do we then need the valves also to change the pitch? Could you not produce all 12 semitones and every note in between with just different buzzing speed? | [
"The way brass instruments work, is there are certain frequencies they are resonant with. This depends on the size and shape of the horn. You can \"lip up/down\" to bend notes, or get sounds close to whats resonant, but they tend not not come out quite as clearly as on-pitch tones. ",
"The valves change the shape... | [
"This is the correct answer. You can buzz your lips at any frequency, but the horn will only resonate if the buzzing matches the internal volume. The valves change the internal volume so it can resonate for whatever note you want.",
"Iirc, without valves you can only play 5ths and octaves, which does let you pl... | [
"Actual horn professor chiming in.",
"Warning: acoustics can get complicated, so I am going to simplify a few concepts to get the main point across. Any resonator (a tube of air, a vibrating string) can vibrate at a pitch whose wavelength is the same as the acoustical length of the instrument. There are two types... |
[
"It's a broad question, I know, but how much do psychotropic drugs typically affect the spinal cord, peripheral, and enteric nerves?"
] | [
false
] | [deleted] | [
"Some to a lot is the broad answer. I'm not aware of a drug that 100% selectively acts on the CNS.",
"Some highlights(each receptor is also found in the affected organs):",
"Mu-opioid agonists cause constipation.",
"Anti-cholinergics cause dry skin/mucous membranes and lower muscle tone.",
"5HT-2B agonists... | [
"To continue this stimulants like cocaine and amphetamines increase release, and/or block the reuptake of dopamine and norepinephrine both peripherally and centrally. Peripheral effects are things like heart rate, respiration rate, sweaty palms, dry mouth, tremors. ",
"There are a few drugs that have a lot of tr... | [
"The not being able to cross the BBB is not true. The blood brain barrier is both a passive barrier that prevents large molecules from freely traveling through the brain, but there's also active ion pumps like the ABC transporter that actively remove substances from inside the blood brain barrier.\nIf that were the... |
[
"Are black holes hot or cold?"
] | [
false
] | Alright so stars obviously burn pretty hot relative to humans, but a question thats been bothering me lately is when something collapses into the singularity of a black hole, is the black hole itself hot or cold if we can even tell. Thanks in advance :) | [
"Black holes have a 'temperature', in that they emit what amounts to thermal radiation. This is called Hawking Radiation, and while not directly observed it's agreed upon by physicists that it probably exists.",
"This temperature, for any black hole we know, is far lower than we'd be able to measure from those di... | [
"And this, in turn, is why Hawking radiation is not yet causing any black holes to shrink. They are all growing by virtue of the surrounding space being hotter than they are. ",
"It would take a solar-mass black hole 10",
" years to evaporate due to Hawking radiation, and a supermassive black hole more like 10"... | [
"It's even lower than the 'temperature' of empty space itself.",
"Just to avoid confusion: That temperature comes from the radiation in space. Space is not completely empty."
] |
[
"Can someone try to explain to me the concept of the \"beginning\" of our universe? My brain fights the concept of the existence of the universe having always just been, without some sort of beginning."
] | [
false
] | null | [
"This question is asked often. You'll find a lot of information by using search.",
"The same question was already asked here: ",
"What Existed Before the Big Bang.",
"And here: [..]",
"There is no \"before\" the Big Bang, because the concept of \"before\" does not apply to the Big Bang. This has been state... | [
"In science, a theory is a well understood model of how a complex system functions. This is very different from the colloquial use of the word \"theory\" which tends to mean \"guess.\"",
"The fact is that we observe that space is expanding and the existence of the cosmic microwave background radiation confirms t... | [
"My understanding is that zellyman understands the idea, but whats to find an easier way to get ones head around the concept. Something along the lines of \"Where's north when you're at the northpole\"."
] |
[
"What's changed since \"A Brief History Of Time\" was published? -physics-"
] | [
false
] | [deleted] | [
"They've discovered that the universe is accelerating (nonzero cosmological constant) and also that neutrinos have mass. Ed Witten hypothesized a theory called M-theory that would generalize all string theories, launching the second superstring revolution, and they found a string theory \"landscape\" which makes th... | [
"Well for one thing, we now know that the universe is 70% dark energy."
] | [
"What about the recent articles I've read about the chances there are no dark matter? It highly contradicted any math theories I've read about the mathematical proof of them.",
"Also, 70% by mass or volume? If by mass, how can that be when mathemtically, iirc, you should end up with equal amounts? Is it because o... |
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