title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"What do people mean when they say 'the specific shape' of an enzyme and substrate? Do they literally 'fit'?"
] | [
false
] | Do they literally 'fit together' like a puzzle piece of some sort or do they bond chemically? | [
"It's a little bit of both, and a little bit of 'same difference.' First, a ",
"video",
", from the supplemental info for ",
"this paper",
".",
"Gorgeous, no? What you're looking at is a drug binding to a protein. Well, that is a lie, actually -it's a ",
" of a drug binding to a protein; the details are... | [
"To add to this excellent comment, the common model for substrate-enzyme interactions is first termed \"lock and key\" by Emil Fischer, and it's exactly how it sounds: just like how a key has a specific shape to push the pins in the lock, the enzyme has a specifically shaped active site that the substrate fits into... | [
"Great answer, just to remind OP: Most enzymes are multiple polypeptides interacting with one another, forming a functional 3D structure, containing numerous secondary structures and are far more complex than what high school textbooks teach you (a square with a indent). Yes, the shape and geometry of the substrat... |
[
"Why do \"campfire smells\" (or other wood-burning smells) seem to stick to clothing/skin longer than other smells?"
] | [
false
] | null | [
"Wood is made of very large molecules that are very closely packed together. While they are combusting, they are not all completely converted to small gaseous molecules like CO2, but rather you get \"volatilization\" of some larger organic molecules that can collect when they cool down - like on your clothes. The... | [
"Yes you breathe in particles of smoke when you're near open fires. It is hazardous to health but the amount of time most people spend breathing in smoke is negligible in relation to a lifetime. But people who spend a lot of time around open fires or indoor fires which are not flued correctly do end up with higher ... | [
"Wonderful explanation. ",
"If you smell a campfire, you are then in turn breathing in large wood particles which are sticky?"
] |
[
"Are there stars that have begun to collapse into black holes, but stabilize before they fully complete the transition?"
] | [
false
] | null | [
"Would you consider a neutron star to be such an object?"
] | [
"Yes (sort-of). Like ",
"/u/iorgfeflkd",
" said, neutron stars could be considered as such. ",
"When a star begins its gravitational collapse, it begins to undergo matter degeneracy, forming denser and denser elements. Neutron degeneracy is one of the final types of matter degeneracy a star undergoes before i... | [
"That's not how it works though. Black holes are extremely high energy, they are only \"dark\" because of their essentially infinite density at the singularity, so something just slightly less than a black hole would be like a neutron star: bright, extremely dense, and extremely high energy and bright. "
] |
[
"Could one perform a gravitational slingshot around a black hole? How effective would it be (if yes)?"
] | [
false
] | Question randomly popped into my head while staring at the Mass Effect 2 main menu. | [
"Yes. As long as you stay far enough away from it, the gravity of a black hole works no different than that of a planet or star. Anything your spacecraft can do around a planet or a star, it can also do around a black hole. Since black holes are more massive than most stars (sometimes by a large amount), the distan... | [
"It steals, or exchanges, velocity. It has nothing to do with the rotation of the object. Also black holes do spin, since they conserve the angular momentum of anything that falls into them (they could theoretically end up with 0 spin, but that's infinitesimally unlikely).",
"A ship conducting a slingshot can onl... | [
"A normal gravitational slingshot doesn't care about spin, as you say. But for rapidly spinning black holes it is possible to extract energy from the spin to gain even more velocity. This is called the ",
"Penrose process",
"."
] |
[
"Can someone concisely clarify differences between PCR types? (qPCR, qRT-PCR, RT-PCR, Real-time)"
] | [
false
] | null | [
"qPCR: quantitative PCR. There are different ways of doing quantitative pcr but the common more accurate way is to perform a PCR with some fluorescent molecule that fluoresces increasingly as product is formed. (I think the other way is called endpoint quantification and you basically can use various methods, som... | [
"...except when they mean real-time. but generally yes, almost no one says rt = real time."
] | [
"...except when they mean real-time. but generally yes, almost no one says rt = real time."
] |
[
"How do spiders not get stuck on their own web?"
] | [
false
] | Seriously, how do they do it? Those things are sticky as shit, how come it doesn't stick to their little legs? | [
"spiders make different kinds of silk",
". They can move along the strands that are not sticky."
] | [
"Oooohh cool. And they still manage to avoid the sticky strands even when attacking their prey? "
] | [
"Yep. Fortunately, venom incapacitates prey so that there's little chance of a struggle that will entangle the spider. Also, spiders have mouths that are designed to eat their silk; they do this to recapture the precious proteins and some of the energy required to spin the silk in the first place. We're getting bey... |
[
"How well can we produce Neuroprosthetics?"
] | [
false
] | null | [
"It's definitely possible to use neuron ensembles as the driving force for neuroprosthetics. The most basic example is a cursor-control device, which is just one or two degrees of freedom. I believe there are some labs (Schwartz or Donoghue) working on control in multiple degrees of freedom. Cortical control of a n... | [
"You use neuron by the very nature of the phenomena. Your muscle contractions are influenced by nerves which are connected to your brain. That's how targeted muscle reinnervation works. You rewire the nerves, essentially. At the moment, it is not possible to connect neurons directly to a prosthetic device–not for a... | [
"They are existent. They are becoming mainstream. Look at Center for bionic medicine at northwestern. That is just one of literally hundreds of places doing research. And this research is happening all over the world. ",
"Keywords for you to google for self-study: BMI, brain machine interface, myoelectric prosthe... |
[
"How long does it take a single electron to occupy the majority of the potential space available to it around an atom?"
] | [
false
] | For the sake of simplicity, a single atom in free space. I understand this answer may change based on the size of the atom; I also understand that the answer to this question may be, for all intents and purposes, instantaneous, unanswereable, or (what I'm hoping for) on the order of femtoseconds. The reason I ask this ... | [
"Are you certain the electron is a point particle? According to classical physics, it has a lorentz radius of 2.8*10",
" m. ",
"The heisenberg uncertainty principle states that the more you know about an electron's position, the less you know of it's momentum. It doesn't state you cannot know an electron's posi... | [
"The radius of the electron is almost certainly smaller than the lorentz radius. I think I recall a recent journal article that had put an upper bound at around 10",
" m. From casual searching right now, the best I can find is an upper bound of ",
"10",
" m",
", but that article is 23 years old."
] | [
"From the ",
"electron's fundamental properties",
":",
"There is a physical constant called the \"",
"classical electron radius",
"\", with the much larger value of 2.8179×10",
" m. However, the terminology comes from a simplistic calculation that ignores the effects of quantum mechanics; in reality, th... |
[
"Is it plausible to take advantage of natural frequencies to disrupt certain unwanted cells?"
] | [
false
] | If so, why is this not being studied more as a means to destroy cancer cells? | [
"What do you mean by \"natural frequencies\"? Frequencies of what? A \"frequency\" is a rate of oscillation of some sort of medium or energy, so what is it that you propose should be oscillated? And what makes a frequency (of some undefined type) \"natural\"?",
"This sounds like a question pertaining to some t... | [
"Because cancer is more of a chemical regulation failure, like the inactivation of tumor suppressing proteins, the over expression of anti-apoptotic protein, a lack of receptors or response to intercellular signaling... the targetable factors aren't really modifying physical properties of the cell like its mechanic... | [
"Yes, thank you. I will possibly repost this with clarification. Do you think physics would be a better flair for this?"
] |
[
"What would happen if an Astronaut in a spacestation with artifical gravity due to a spinning station would jump?"
] | [
false
] | I just watched a sci-fi show with such a system and I came up with this question. My problem here is as follows: The system works by using the centrifugal forces comming from the rotation of the wheel. So, everything that is speeded up to the speed of the wheel would feel artificial gravity. The problem is that the Ast... | [
"shouldn't the Astronaut when making a little jump [...] negate the effect of the spinning wheel",
"No. During the jump the astronaut will keep moving sideways due to inertia. Since the astronaut is moving in a straight line and the floor is moving in a circle, eventually they will come closer and he'll land near... | [
"I recall reading production notes on the making of ",
", which stated that the producers of the film knew that the centrifuge at the center of ",
" was small enough in its circumference that in a real spacecraft the astronauts would almost certainly feel dizzy from the coriolis effect- it would take a centrifu... | [
"They've actually tested this in centrifuges, and the effect is overblown. While the coriolis effect would make you dizzy, being in space to begin with already makes people sick until they've had a dozen or so zero g experiences. That's why zero g flight simulators were originally called 'vomit commets'.",
"Nearl... |
[
"When measuring the energy of a lightning bolt, or any electrical discharge, is the energy of the bolt uniform through out it, or does the energy decrease as the bolt travels to its \"target\"?"
] | [
false
] | edit: i should've added that the energy decrease would be due to energy dissipation to matter around it. | [
"The energy (actually ",
" dissipation) can vary depending on the position along the bolt. This can be affected by things like atmospheric density, humidity, wind velocity, pressure, dusts, etc. As an example look at ",
"Paschen's law",
". You will notice the voltage varies non-linearly with pressure. This w... | [
"Electrical discharges happen when two surfaces (in this case the ground and the clouds) have such a strong voltage difference that electrons temporarily flow through the insulating medium between them and reduce that voltage difference. Since the electrons move from a region of high electric potential to low, thei... | [
"What is interesting is that if you apply the Paschen curve to the cloud to ground voltages, lightning generally should not start. Recently there is evidence that the ",
"ionized path that starts the bolt comes from cosmic rays",
".",
"Measurements of the electric fields in clouds could help to solve the one ... |
[
"How realistic is the goal of putting humans on Mars by 2023?"
] | [
false
] | Personally, I'm very excited about the idea, but I have no idea if it really is a realistic idea. Is it? (If you don't know what I'm talking about: ) | [
"Mars One quickly became obvious as NOT a realistic idea. The team behind it did two reddit AMA's and weren't able to answer even basic questions about the idea because the team isn't made up of scientists and engineers but PR people promoting the idea.",
"The gist of their idea is that other companies would have... | [
"It's not a science issue. It's politics. We've had the technology to start colonizing Mars ",
"years ago",
"."
] | [
"We already have technology more than capable of it, so the only real question is \"How much funding will go towards making this happen?\" thus making it not a question about science so much as politics."
] |
[
"Do 'XX days without an accident' signs correlate with lower accident rates?"
] | [
false
] | null | [
"This might have made a better question in Ask Reddit sub. Without any experience in psychology I can only answer from experience having a sign like that in my store.",
"It wasn't until there was an incentive to having so many days without an accident that made a difference. It resulted in less reported accidents... | [
"I can't really find anything on it, so I can't provide you with research results.",
"My thoughts are that those scoreboards might make people more aware of safety in the workplace by reminding them of it, and may cause people to pay more attention to safety.",
"\nIt may also serve as a competition for people t... | [
"Potentially. The kind of place that would put up a sign like that, and keep it updated, is likely to be very concerned with safety. A place that wasn't very concerned with safety wouldn't be likely to have one of the signs."
] |
[
"If I stood directly on one of the Earth's axial poles and looked straight up on a cloudless night, would I be able to notice the stars \"spinning\"?"
] | [
false
] | I would imagine it would be pretty slow even if I could. | [
"The Earth spins 360 degrees in 23 hours 56 minutes, so a quick bit of calculator magic gives 0.004 degrees per second, or 15 arcseconds per second. That's pretty difficult to notice, even with a telescope - from memories of small telescope, you could notice the change in position if you looked away for a minute or... | [
"Yeah, and you can do that anywhere in the world (though if you're on the equator the point they 'spin' around is on the horizon). People often make time-lapse videos of this and post it on youtube or take long exposure pictures - ",
"here are some."
] | [
"There is nothing special about those locations with regard to this question.",
"If you are in the northern hemisphere you can look at the celestial pole anytime you have a clear sky.",
"And stuff does move there, but it moves even more slowly than stuff does elsewhere in the sky. You can see it move, but you n... |
[
"Is it possible to create a vacuum in a straw with the width of a swimming pool?"
] | [
false
] | To go into more details, if we had lets say a straw that had the width of a swimming pool, could we theoretically create a floating pool of water above our heads if we created a vacuum at the top of the massive straw? I know the straw would have to be HUGE but is it even possible? Sorry if I worded that weirdly. Not su... | [
"Not really ion the classical straw sense. The max force air pressure can exert is 14.1 psi (at sea level). Which is enough to hold up about 32\" of water depth. However, this won't happen because the water would still just flow out because water the pressure can't act across the surface as a whole. The reason i... | [
"Just wanted to say it's 32 feet (') of water not 32 inches (\"). I'm guessing you probably meant feet but used the inch symbol. Also it's probably better to say that atmospheric pressure is pushing the water up than to say that the water is levitating."
] | [
"I don't see why your hypothesis would work. Air pressure is for all intents and purposes, static and would not be affected by a non-moving object."
] |
[
"Two guys are squatting. One of them can squat a maximum of 150kg, and the other one a maximum of 110kg. Do both of them consume the same amount of calories when squatting 100kg?"
] | [
false
] | null | [
"Short answer no, because I would expect the guy with 150kg max to weigh more therefore he's squatting more in total. But to answer more what I think you're getting at, it depends on a lot. They have to do the same amount of work on the bar (assuming they squat it the same distance) but work performed does not equa... | [
"So differences in efficiency could (would) cause their metabolic energy consumption to be different.",
"Yup. It's so hard to answer any of these questions because neuromuscular recruitment pattern efficiency is so different from person to person.",
"Almost every response to questions like these is going to be ... | [
"Let's use an exercise as an example, say a bicep curl. When you workout and do bicep curls 3x/week, you will find yourself being able to lift more weight as you get stronger. The reason this happens is ",
" because of neuromuscular adaptations. Yes, the fibers will hypertrophy, but what's really happening is tha... |
[
"Blue Eyes Problem"
] | [
false
] | I was just thinking about the Blue Eyes problem. Everyone seems to agree that the problem ends on the Nth day, but I think it should happen much earlier than that. Before the first night all blue eyed people see N-1 people and can deduce that each blue eyed person is able to see at least N-2 people with blue eyes. Ther... | [
"I can't follow your argument, but it plainly fails if you just look at a simple case:",
"Say I'm on the island. I look out and see three blue-eyed people. I know each of them sees at least two blue-eyed people. So no one leaves the first night. Now we're on day two.",
"If I don't have blue-eyes, then they each... | [
"This is an example of \"proof by induction\"",
"Solve it for 1 person first (it's trivial)",
"Then for 2 people",
"Then use that as the base case to add a 3rd person, then a 4th etc.",
"You will see the pattern emerge.",
"This is how you would be taught to solve a problem such as this in a formal logic c... | [
"The group on the island can't collectively agree on what N-2 should be.",
"Given there is 100 blue eyes on the island and 100 browns eyes:",
"If you're an island with blue eyes, you'd count 99 blue eyes on the island and assume the first day would be 97 (blue eyes leaving)",
"If you're on the island with bro... |
[
"How do most otherwise healthy people find out they have cancer?"
] | [
false
] | I mean, how do they know there's something wrong when they don't feel sick? | [
"I suppose there are a few ways of answering the question.",
"They don't. Many people have subclinical or undetected cancers that simply will never manifest themselves. This is why cancer screening tends to have an upper age bound - after a certain point, you may be 'catching' a cancer that wouldn't have matter... | [
"That's generally how it's caught - the tumor(s) got big enough to finally start causing issues. Can't really answer you about early symptoms because there really aren't any (hence it's high mortality rate - it's caught in late stages) but in general, when we see patients that are in late stage lung cancer and don'... | [
"So for example if I were to have lung cancer when would I notice the symptoms? Are there actual symptoms? Or would the cancer just keep growing until it got big enough and invasive enough for me to feel pain in the area around it? I would assume that a decent sized tumor on my lung or heart would actually cause me... |
[
"Why did they need so much code to take the black hole picture?"
] | [
false
] | Why couldn't they have just used a telescope, pointed it at the black hole and just took a photo of it? | [
"It's a bit more complicated than that but that's kinda right. The picture was reconstructed using long base interferometry. Basically they look at light (radio waves in this case) from multiple antennas at once from all over the place and the difference in the phase from light emitted at the same time is analyzed ... | [
"It is not a photo. If you just point a telescope in the sky you'll never get anywhere close to the resolution they needed.",
"They pointed several telescopes at it for days and recorded everything: For each pixel, measure the intensity and phase of the radio waves as often as you can. That creates thousands of t... | [
"I'm confused... You sound like you're trying to correct me, (you lead with the word \"except\")... but nothing you said contradicted what I said.",
"To be more pedantic and hopefully clear up what I'm saying, they are measuring the interference patterns of EM waves at known locations in 3D space in order to cal... |
[
"What's the difference between something colored white and a mirror? Don't they both reflect all visible light?"
] | [
false
] | The color white reflects all wavelengths of visible light, so why does it differ from a mirror, which reflects visible light more obviously? | [
"The mirror will reflect the light but keep it going the same way, just bounce it off at an angle. This keeps the light going the same way so you can recreate an image. With the white object light bounces off of it but will scatter, or go off at some random angle. This causes the object to appear white because the ... | [
"Good answer. Another cool effect: at grazing incidence, many white things are quite reflective. Try looking at a bright light nearly parallel to a piece of paper."
] | [
"Simple analogy: it's like bouncing a ping pong ball off of a table vs a gravel road.",
"Google reflection and refraction for more info."
] |
[
"So, this is kind of a combination of social science and a lot of other disciplines: clearly ads are effective, but how much are they effective? If I want to get a streaming service, how would I calculate the value of buying it with or without ads? Is buying the ad-free service actually saving money?"
] | [
false
] | null | [
"Are you asking about effectiveness from the product perspective (e.g. how do attribution models work -- how can we say how many sign-ups for a service are due to a specific tv ad campaign vs. a billboard vs. an online ad buy) or are you asking from the consumer perspective about how much purchasing behavior, on av... | [
"I am asking how to find out how much ads are making you pay on average."
] | [
"Do you mean something like how much are you paying for things from ads that you click on? At an individual level, that's impossible to answer. Most people never click on ads.",
"We can try to answer a related question: what's the conversion rate for Hulu ads? Or something like that. However, this isn't really a ... |
[
"What advice do you have for high school students interested in careers in science?"
] | [
false
] | [deleted] | [
"If you have a career in science, there is a very very high probability it will involve a good amount of computer programming. Plus, it is a skill that can be easily learned at the high school level. Plus it is a good way to start developing the sort of structured logical thinking that is necessary in science."
] | [
"When you start looking at colleges ",
" Undergraduate research is important for two reasons. First, it allows you to see whether or not you like ",
" in a certain field as much as you like ",
" it. Second, it definitely helps when applying for grad school or jobs."
] | [
"Read about every area and figure out what interests you most to get a grasp of the main direction you might want to head in. Websites like ",
"this",
" give you an idea what is going on at the moment and you could take part in, though they still only show part of a much larger picture. Popular science books ma... |
[
"Do rockets (or VTOL capable vehicles) generate more upwards thrust the closer they are to the ground?"
] | [
false
] | Sorry if the question is confusing, but basically I'm wondering if any vehicle that uses a jet or rocket engine vectored against the ground on takeoff will need to spend less energy the achieve the required lift, due to an almost normal force effect because of the proximity of the jet engine to the ground? Like would a... | [
"What you have said is true for things such as hovercrafts, where there is a skirt to prevent air from escaping and thus pressure builds up. Similarly, if a rocket nozzle is placed directly on the ground and ignited, then you would get an effect from pressure buildup.",
"No rocket is fired in this manner, however... | [
"You might think this, but you'd be wrong. Consider the case in which the cones are set directly on the ground. When you fire up the rocket, what happens? The thrust must clearly be greater than the case where the nozzle is unobstructed, because you'll get the full contribution of the momentum thrust, plus that ... | [
"Not really. A rocket's thrust comes from accelerating propellant out of the back of the rocket and conservation of momentum. See here: ",
"http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation#Derivation",
".",
"Whether the fuel hits the ground or not after leaving the rocket doesn't really matter since i... |
[
"Why is it that when you turn on a fluorescent light, it flickers before becoming a stable light source?"
] | [
false
] | null | [
"Florescent light works by having electrons pass from one electrode to the other. This forms what is called an \"arc\".",
"To get the lamp started you need a spike of high voltage to get the arc started. Older lamps used a starter to get the lamp going. Modern lamps use pulse start which is done by components wit... | [
"Good answers so far, just one thing I think was left out.",
"As to why it flickers a lot when turned on is because the gas inside is cold. When cold it takes a lot more energy to create the glow discharge.",
"So the starter tries to start it, gets a short discharge that quickly goes away but also warms the gas... | [
"I know starters were replaceable. What would break down in the starter?"
] |
[
"If light has no mass, then why can't it escape a black hole?"
] | [
false
] | I may be missing a few pieces of information here, but doesn't gravity act solely on objects with mass? If light has no mass, why can it not escape the gravitational pull of a black hole, and thus just continue on its way? Again, I'm not a science buff, just wondered this earlier today. | [
"The idea that gravity only works between massive objects is one of those convenient mistruths you learn in high school. As far as everyday life is concerned, that's true, and Newton's gravity - where gravity is a mysterious force at a distance - holds for most experiments you'll do.",
"But it's not the most fund... | [
"FAQ"
] | [
"One of the things that I'm not really clear on is how gravity can simply be a manifestation of curved spacetime, but also be a force mediated by the exchange of gravitons (ok, given that we find them some day). Could you (or anyone else) expand on this a bit?"
] |
[
"Is it theoretically possible to reach space in a hot air balloon?"
] | [
false
] | null | [
"It depends what you mean by space. You can get through several layers of the atmosphere in weather balloons which could be considered \"space\" but balloons work because they are less dense than the surrounding air (because they are fill of hot air). Seeing how there is no air in space the best you could hope for ... | [
"I think if you REALLY want to break it down it's a much more complicated question because when net buoyancy stops all that means is you no longer have an upward ACCELERATION. You still have a velocity though. So ultimately the question is: is it possible to reach that point with an upward velocity of the escape ... | [
"You're confusing pressure with density. "
] |
[
"Why is the Woolly Mammoth the main subject of most cloning projects?"
] | [
false
] | It just seems an odd pick. Why? EDIT: I guess it would be more accurate to say "the subject of cloning projects" | [
"It's not really the main subject. ",
"List of animals that have been cloned.",
"I would say it gets the most press because Woolly Mammoth are extinct and it would be amazing to see a live Woolly Mammoth. Cool science gets more exposure than boring experiments like carp cloning.",
"Edit: Oh gosh, I thought th... | [
"because there are specimens that have been found very well preserved in ice."
] | [
"Hopefully this doesn't count as \"layman speculation\" but I remember an article about this that talked about using elephants as surrogate mothers for the cloned mammoths. I would assume that of any extinct species we have enough samples of to produce a clone, the similarity between elephants and mammoths is great... |
[
"I've read that muscles can only pull, never push. Would it make a difference if they can only push and never pull? What about a mix?"
] | [
false
] | null | [
"If we forget about all the math and newtons in pushing vs pulling; anatomically I think it would be kinda awkward to have blobs of muscle that would flatten out. Would be pretty uncomfortable to sleep if something kept protruding in your back because it neede to be in a resting state. "
] | [
"The opposite action of muscle contraction is hydraulic action. Your skeletal make up would be entirely different if things pushed. You would be built more like an excavator than a human in that things would be designed to work under compression, rather than tension."
] | [
"This question has been removed because highly speculative in nature. Exceedingly imaginary hypotheticals often invite non-scientific speculations.",
"For more information regarding this and similar issues, please see the ",
"FAQ."
] |
[
"Why doesn't everyone get a rabies vaccine?"
] | [
false
] | I heard rabies has a , so why doesn't everyone just get a vaccine and then we can irradiate it like small pox? | [
"Because the likelihood of contracting rabies is so low its not worth the risk and hassle of giving everyone the shots. Very few people come into contact with rabies infected animals, and even fewer are bitten by them. There are exceptions for animal control workers and cave explorers because they have an increased... | [
"I agree with everything stated here, and would only like to add that in response to the second part of OP's question",
"then we can eradicate it like small pox",
"To rid the earth of rabies, you would also need to vaccinate every animal on earth that can contract rabies (",
"pretty much all mammals",
"). T... | [
"\"Wears off\" is relative. Some individuals mount a strong enough antibody response such that they don't need to be revaccinated for longer periods of time compared to individuals who clear antigen quickly and don't have a sustained antibody response.",
"As veterinarians, we are highly recommended to get the va... |
[
"If a normal person has a brain altering incident (like a severe condition) and becomes stupid, if a genius goes through that same incident will (s)he become normal, or stupid as well?"
] | [
false
] | null | [
"This question is too vague. There are lots of possible injuries and lots of possible effects. "
] | [
"Well I tried to make this ceteris paribus in what the possible injuries and effects could be. You know this better than I, but think of an injury that could make someone stupid? If that same injury struck two different people with varying levels of intelligence the same exact way, will those people end up still wi... | [
"There is no single intelligence center of the brain and, although there is general functional overlap across individuals, it is not perfect. So damage to some area across two individuals is not at all guaranteed to have the same effect or at least to the same extent. Even for gross disorders like Wernicke's aphasi... |
[
"When sonoluminescence occurs what happens to all that heat produced?"
] | [
false
] | I asked this question a couple days back and no-one replied which makes me sad cause I wannna know lol. | [
"Virtually all of it (minus the light emitted) just gets absorbed into the water, giving a small net increase in its temperature.",
"Keep in mind, sonoluminescence involves a vanishingly small amount of energy (",
"8x10",
" J, according to this quick and dirty estimate",
") per bubble; we only get such an i... | [
"It is a high temperature but very very tiny amount, so the rest of the water surrounding it easily absorbs that heat. Think of pouring a cup of boiling water onto the ocean. The overall temperature of the ocean will hardly change."
] | [
"It's a matter of scale.",
" ",
"Only a very, very, very, very tiny amount of \"stuff\" gets that hot. It's so small, it's almost nothing. If you take almost nothing, and heat it very hot, then overall you still have a lukewarm glass of water sitting under a speaker.",
"Think about it another way: If you ... |
[
"How do pigeons do so well in urban environments?"
] | [
false
] | [deleted] | [
"Man, this is a great question. I am undertaking a project right now on crows which is based off of Kevin McGowan's projects at Cornell on existing Ithaca populations. He's written several papers on urban exploitation by birds and why it occurs.",
"Some animals are trapped by urban environments. They may do we... | [
"pigeons are a ",
"generalist species",
" and the common pigeon in cities is the rock pigeon which historically nest in/on cliff faces. Buildings are essentially artificial cliff faces. There is also a lack of natural predators in cities, such as peregrine falcons and sparrow hawks. Instead of me trying to soun... | [
"They're not cross-breeds. The pigeons you see in cities are rock doves, which are a single species."
] |
[
"Why can I consciously control by speed of breathing, but not my heart rate or body temperature?"
] | [
false
] | To give an example: When sporting, I control my breath (slow tempo) to be able to keep on going longer. I consciously control this tempo, and I can alter it at any moment. However, I cannot control my body temperature or heart rate, which at some points can be an issue (overheating for example). Is there any reason for... | [
"This happens because of the way our nervous systems are divided.",
"We have two main neurological systems, somatic and autonomic. These are part of the peripheral nervous system, which connects your brain and spinal cord to other organs and tissues, such as your heart, lungs and skeletal muscle (the muscle on y... | [
"you can control your ",
"heart rate",
" and your ",
"internal temperatures",
", just not instantaneously. ",
"Heart Rate control is most easily seen in the the speed with which ",
"Bi-athlete's drop their heartrate",
" before shooting.",
"Internal Temperature control can be seen in ",
"polar wat... | [
"From an evolutionary standpoint, the reason breathing is much more easy to consciously control than heart rate or temperature is because it involves sucking in some of the external environment, bypassing a large portion of your protective systems.",
"If you couldn't control it based on your conscious processing ... |
[
"Will Mars become more habitable as the Sun gets bigger and hotter?"
] | [
false
] | null | [
"There is a 'Goldilocks' zone around any given star at any given point in its life, called the habitable zone. This is defined as the point at which the planet is warm enough to have liquid water on its surface. \nWhen the Sun expands Mars may well be within this zone, however Mars has little to no atmosphere so wh... | [
"The habitable zone is a little broad, and Mars and Venus might actually be in the generic area.",
"Once Mars heats up, its atmosphere could thicken and cause a chain reaction, which is exactly what I think OP is getting after. Obviously the atmosphere is CO2 (for now), but with lots of time and introduced life,... | [
"The primary reason mars has very little atmosphere ... is that it simply isn't large enough to hang onto one.",
"This isn't true. We actually don't know why Mars' atmosphere is so thin (it's not in line with just being small). It will have lost of a lot due to the interaction with the solar wind and cosmic radia... |
[
"Average distance to a star's nearest neighbor is asked all over, but what's the distribution on that look like?"
] | [
false
] | So after some researching around, I know that the average distance from one star to the next closest star in our region of the galaxy is about 5 light years. But I'm wondering on what the distribution of that looks like, and I haven't had any luck finding anything on that. Is there any data on the distribution of "dist... | [
"I apologize-- my mind hasn't wandered to territory as nearby as stars in a while, and I completely forgot about parallax techniques. ",
"Not with the precision you would need to measure individual galaxy distances to their neighbors, as this is dominated by random motion and gravitationally bound clusters.",
"... | [
"Within a region of constant star density, the star positions are basically independent of each other. On average, a sphere with 2 light years radius will contain 8 times the stars of a sphere with 1 light years radius - as this number is much smaller than 8, you can approximate this as 8 times the probability that... | [
"Aha, okay. Yeah, this all makes sense now that you lay it out like this; I didn't think about trying to derive it, but this probably is a lot easier than pulling it out of a dataset.",
"Thanks!"
] |
[
"Why does Hydrochloric Acid dissociates more than Sulfuric Acid, or more than most other acids for that matter?"
] | [
false
] | This question comes from one I asked my chemistry teacher: how can we tell apart strong acids and bases from weaker acids and bases by JUST knowing their name (ie KOH, H3PO4, etc) and properties we can derive from the periodic table, atomic structure, so on. My teacher's answer kept coming down "strong acids and bases... | [
"Several factors must be considered, here are the main ones:",
"Electronegativity - this is most commonly understood and talked about. The more electronegative the atom bonded to the proton is, the more easily that bond will break heterolytically (both electrons go with one partner, aka the leaving group). It m... | [
"Perfect answer. And hey, OP, check out carborane (super)acids for some extra fun. Also since it sounds like you've got a prof who doesn't know their shit, please keep in mind that strong acids are not the same as corrosive acids! Some strong acids are drinkable, others would bottom out your throat before you fi... | [
"Bond length matters too. So the larger the anions’s size, the stronger the acid. For the halides this means the weakest acid is HF and the strongest is HI"
] |
[
"Why do we tend to wet our pants when we get scared? And is it a common occurrence?"
] | [
false
] | I've heard a lot of stories about people playing horror games, and when they get really scared, and thus wetting themselves. So I wonder: Why does this happen and is it a common occurrence? You learn something new every day, thanks guys. | [
"Classic animal response, i saw it constantly as a field biologist. Historically, a major source of fear is not wanting to die. A major source of dying is being eaten by predators. And really, who wants to eat something covered in urine and feces? Kinda nasty. Its always a good idea to appear unappetizing. Look at ... | [
"Sympathetic nervous system stimulation associated with the \"fight or flight\" response results in bladder relaxation. "
] | [
"It is not due to the fight or flight response. Bladder voiding is triggered autonomically by the parasympathetic nervous system. There are two muscles primarily involved: the detrusor muscle surrounding the bladder, and the internal urethral sphincter at the exit of the bladder. Parasympathetic activation relaxes ... |
[
"Can you scare someone enough to give them an adrenaline rush to counter an allergic reaction?"
] | [
false
] | Seeing as serious allergic reactions are countered with epinephrine injections... | [
"My initial thought would be that someone under the stress of an anaphylactic reaction would already be pumping out plenty of catecholamines on their own and that you wouldn't be able to add much more to that by scaring them.",
"But I found some data, too.",
"This study",
" compared epinephrine concentrations... | [
"People going into a serious allergic reaction are already panicking, and this physiological response is not sufficient to counteract the effects of the allergic response. So no."
] | [
"\"Supraphysiological concentration\" . . . also known as a pharmacological concentration.",
"Overall, however, I had the same interpretation. This question boils down to an explanation of the difference between physiological and pharmacological concentrations of natural substances.",
"Also, I've never unders... |
[
"Does washing hands in water that is hot to the touch actually kill more germs than washing with water that is cool to the touch?"
] | [
false
] | Just like visible light and audible sound, the range of temperatures that is tolerable to human flesh seems quite narrow. I was wondering what are the odds that water at the highest temperature tolerable to a person would also be enough to effectively kill microbes? I understand that many solids do have a noticeable di... | [
"I disagree about the hand sanitizer. Soap and hand sanitizer work in completely different ways. Soap removes bacteria whereas hand sanitizer denatures surface proteins and lipids to kill the bacteria. However this killing effect is something that can be worked around through evolution. This is especially true ... | [
"It's actually an extremely common misconception that washing your hands with hot water will kill bacteria on your hands. Soap and water essentially create a mixture that attaches to oils and other grime on your hands, which house bacteria, and allow them to slide off when rinsed. Because these bacteria are livin... | [
"There is no way bacteria can develop meaningful resistance to alcohol based hand sanitizers."
] |
[
"Why is there a reflective ripple on the pavement of the road when looking at it from a distance(noticeable when driving a car)?"
] | [
false
] | Whenever I'm driving I can see the tires of the car reflected in the road as like almost silvery and wavering. It happens during the day time from what I've seen and only when looking from a considerable distance. | [
"This is heat distortion caused by changes in the density and movement of the air.",
"Light refracts when it goes through objects. When you look down through the surface of a pool objects under the watter appear to dance, wiggle, or distort. This is because the light traveling through the water slows down, and th... | [
"You're probably referring to an ",
"inferior mirage",
". It's simply a naturally-occurring phenomenon that is triggered in hotter temperatures. The sky is reflected off of the roads at certain angles, and is interpreted by our minds as a pool of water."
] | [
"That sounds like a mirage, many people know that phenomenon because it makes it seem like there is a source of water in the distance, but what is really is, is the light rays being bent to produce a displaced image of an object. When you see a source of water in the distance, the sky is displaced to look like it's... |
[
"How did early chemists know when they had isolated an element?"
] | [
false
] | I enjoy learning about the history of science. I'll often read something like "Radium was discovered by Marie Curie and her husband Pierre on 21 December 1898" (from ). Sometimes the histories will give a few details about how they knew it was a new element, but it has always intrigued me how early chemists were able t... | [
"Spectroscopy is a rather large field that helped out with the discovery of individual elements. Most well known is the discovery of Helium by Pierre Janssen using this method.",
"Here's a rather short infographic regarding some of the basics behind it. I'll defer* to the rest of the community regarding anything ... | [
"Aristotle's definition of an element",
" is pretty straightforward- it is a substance that can be obtained by decomposing other substances, but cannot itself be decomposed into other substances. As you probably know, the classical Greek elements all turned out to be incorrect, but the basic idea of trying to se... | [
"I'm really late to the party here, and this comment will probably be buried. Nonetheless, I've read a couple of REALLY good history of science books. They're written to be accessible to all audiences, whether you have a background in science or not. They are both by Sam Kean. \nOne is called \"The Disappearing Spo... |
[
"Can power spectral density analysis only be performed up to half the frequency of the sample rate?"
] | [
false
] | Context is that I work in a lab that studies seizures in a mouse model. I was given the data from the EEG recording and asked essentially to perform PSD analysis on it. I've researched this and tried different methods for a couple weeks now, and it seems like no matter what I try, my DFT is symmetric about 50 Hz, which... | [
"You're seeing the ",
"Nyquist rate",
". You're right, you'll need >120 Hz to see 60 Hz without aliasing."
] | [
"What other people here said, but I'll just add that there's frequency content in the EEG up to about a kilohertz, so even if you up your sample rate to 120 Hz, you're going to need to analog low-pass the signal otherwise you'll alias higher-frequency stuff.",
"And, as you probably know, stuff around 60 Hz is a b... | [
"Astrokiwi is right, but you also need to make sure you have a filter to get rid of frequencies higher than half of your sample rate. Aliasing will ruin all of your data, not just the data above half of your sampling frequency. ",
"http://en.wikipedia.org/wiki/Aliasing",
" explains the basis of it, but in short... |
[
"Are bees the best pollinators? And could other pollinators take their place?"
] | [
false
] | Why are bees held in much higher esteem than other pollinators? Are they the most efficient pollinators? And if so, what gives them the edge over other pollinators? Additionally, if bees dissapeared today would it be possible for plants to be pollinated just as efficiently if an extant species rose up to fill in the be... | [
"Different plants are adapted for pollination by different means - grasses are wind pollinated, many crops are bee pollinated, some plants are pollinated by other insects or vertebrates. The degree of specificity varies, with some plants requiring a specific insect species and others being pollinated decently well ... | [
"The problem is bee extinction is just one of many problems we are facing at the same time. The vast majority of mammal and avian biomass on the planet is human and livestock. 40% of all habitable land is being used for agriculture. The population is unsustainable and still growing. Climate change, pollution, overf... | [
"In addition to what others have said, bees also have a tendency to stick to one group of flowers at a time. For example, if they’re sipping nectar from say lantana, they’ll stick to that lantana bush. Whereas, a butterfly, for example is more random...”hmmm this lantana looks nice, oh wait look at that penta!” For... |
[
"How are new mutations successfully inherited by progeny if the mutation is only present in one progenitor?"
] | [
false
] | Wouldn't the mutation be weeded out after one generation? I am trying to understand this in terms of alleles but I understand that it may go beyond this. I am sorry if this has been asked before; I was not sure as to the best way to word the question. | [
"Here's ",
"an interesting paper",
" that explains how that might have happened in the case of human/chimpanzee divergence. "
] | [
"well there are two alleles in each parent yes? depending if the mutation is homozygous or heterozygous, the chance that the parent will pass on a mutation is either 100% or 50% respectively.",
"A mutation can still be passed on, even if only one parent has it. Its just like any other trait... all traits in essen... | [
"You're partially right; even if the mutation is very beneficial, it has a large likelihood of being weeded out. In evolution, everything is subject to chance to some degree. Genetic drift is a large force for evolution (change in allele frequency over generations), but it isn't talked about as often because it's l... |
[
"What is the fundamental difference between a space dimension and a time dimension?"
] | [
false
] | Referring to this SMBC comic. Why would multiple time dimensions make travelling through space easier? | [
"Having more than one time dimension would allow you to construct reference frames where you can essentially time travel. It would be very easy to get around if you can, in essence, get somewhere before you left if you wanted.",
"In reality though a universe like that would have no physics that we could extrapol... | [
"actually this is a fascinating thought experiment. a universe of say 3 time dimensions and 1 spatial dimension. life-forms just endlessly sliding involuntarily down the one possible Trajectory of Existence, but hey at least they can rewind and fastforward all over the place which is precisely how they navigate t... | [
"https://arxiv.org/abs/gr-qc/9702052"
] |
[
"Cats & Dogs have many nipples. What creatures have the most nipples. Why?"
] | [
false
] | null | [
"From ",
"https://en.wikipedia.org/wiki/Mammary_gland#Other_mammals:",
"\"The number of nipples varies from 2 (in most primates) to 18 (in pigs).\"",
"\"The nipples and glands can occur anywhere along the two milk lines, two nearly parallel lines along the ventral aspect of the body. In general most mammals d... | [
"Wild pigs will have around 12 to 16, even 20 babies every time. They are a huge problem here in Texas because of this. And they ALL live. "
] | [
"Large mammals are typically only preyed upon by snakes, birds-of-prey, and apex predators mammalian and reptilian. In the case of wild pigs, the expected predators are wolves and their like, but wolves don't coexist with large populations of humans. The same problem exists with kangaroo and deer in Australia and ... |
[
"After watching the recent Black Mirror episode \"Metalhead\" and comparing it to my own experience with drone development, I am wondering what obstacles science must overcome before autonomous hunter-killer drones may be developed?"
] | [
false
] | null | [
"Such questions are better suited for our sister-sub ",
"/r/asksciencediscussion",
". Please post there instead."
] | [
"Roger, will do; for the future, what would make the post suited for AskScience versus Discussion? "
] | [
"Any sort of hypothetical, speculative, or open-ended questions. Or questions asking for opinions, lists of pros and cons, etc. On ",
"/r/askscience",
" we try to focus on empirically addressable questions."
] |
[
"If secondary protein structures are so energetically stable, why are molecular chaperones required to assemble them?"
] | [
false
] | Why do they not automatically assemble this way when the primary chain reaches equilibrium, as it is the most energetically favourable state? Is the desired secondary structure truly the most energetically stable? My guess would be that imperfections could arise, as some configurations are slightly more favourable, but... | [
"As ",
"/u/rupert1920",
" has said, Levinthal's paradox states that it would take longer than the age of the universe for a polypeptide of 100 residues to fold into the correct configuration by \"trying\" all phi/psi angles. Anfinsen et al (Anfinsen, CB et al (1961) ProcNatAcadSci 47, 1309-1314) showed that pri... | [
"Disclaimer: I'm not an expert in protein folding, and would love to be educated more on the matter.",
"Check out ",
"Levinthal's paradox",
", which states that the sheer degrees of freedom a protein has makes it highly unlikely to spontaneously fold into the energetically stable conformation. Which means tha... | [
"I would say that rupert1920 has the majority of the answer, but I would also like to add a caveat. Most chaperone proteins actually serve a dual purpose. ",
"The first and most intuitive purpose is ensuring that the native state of the protein in question is the most energetically favorable. The second purpos... |
[
"Old 3D video games rendered circles as visibly crude polygons. Modern games have them perfectly circular. Did we just increase polygon count until its too high to notice, or have rendering algorithms changed to allow \"true\" circles?"
] | [
false
] | null | [
"We increased polygon count and have considerably more filtering options to smooth out jaggies. But even with no smoothing/anti-aliasing a simple 32 sided polygon is nearly indistinguishable from a circle even at ",
"large zooms"
] | [
"The amount of polygons rendered has increased, tessellation allows meshes to be subdivided during runtime and detail can also be added by many different techniques, displacement maps to displace vertices, normal maps to add fake bump effects to a mesh, shaders have come a long way too but 3D graphics is all still ... | [
"Modern games have them perfectly circular",
"No, they don't. They are just cheating it so good that it becomes hard to notice.",
"On old graphics cards, with built-in rendering pipeline, you could only really control vertices. This meant, if you wanted high-quality circle, you had to use lots of vertices.",
... |
[
"How rigorous are the concerns about the speed of neutrinos?"
] | [
false
] | null | [
"Can you clarify your question?"
] | [
"There are always reports that neutrinos are getting caught breaking the speed limit, then later those reports are chalked up to measurement error. So originally my question was more about accounting - had every report about neutrinos moving too fast been debunked by BETTER science or were there a few good cases s... | [
"That \"new\" article was published in 2011, it was a false signal due to a loose cable."
] |
[
"Why do the Japanese live so long? In other words, why does Japan have longest life expectancy in the world?"
] | [
false
] | Surely there must be some research into the topic. | [
"Funny story. They recently discovered that a lot of old Japanese died long ago, but because of the economic depression there (which is lasting decades) their kids don't notify the authorities so they can keep the pension payments, etc.. They started an investigation a year or two ago and I don't know if the longev... | [
"Sounds interesting. Got a source?"
] | [
"I ",
" I read it here first ",
"http://www.guardian.co.uk/world/2010/sep/10/japenese-centenarians-records",
" but there were some other similar reports. It is hard to believe figures like these did not impact average age statistics."
] |
[
"A space question"
] | [
false
] | [deleted] | [
"In perfect space it would go forever and never slow down. Newton's first law.\nIn real space there are a small amount of particles the object would hit while travelling and it would also be affected by the gravity of other celestial objects. "
] | [
"One comment mentioned that space is not really empty, so this is one. Second, the gravity of every particle acts on every other particle in the world so depending on where in the universe you launch-yo will get your object pulled in a direction. If you imagine a universe with only your object in it so no gravity s... | [
"An object in motion stays in motion unless acted on by an external force. Newtons first law of free bodies. So if space was completely vacant of all material than the object would translate indefinitely. The problem is space is not completely vacant. In \"most places\" you will run into some particles that then ca... |
[
"On the average frequency of of electro-magnetic radiation and the quantum state of electrons"
] | [
false
] | Layman here, trying to conceptualize QM from the ground up. Since the frequency of an electro-magnetic wave determines how much energy is imparted to an electron and thusly determines its orbital position (as evidenced by the photoelectric effect), can we postulate that certain positions are more favorable than others ... | [
"A photon can have any wavelength you can think of. An electron when bound to an atom can only occupy certain states, this is not the same as positions, in fact we can't say much about the exact position of an electron in an atom - only something about how likely each position is. The CMBR was emitted at around 300... | [
"Honestly, i don't see the importance of its exact position within an orbital plane, only knowing which orbital it has jumped to seems significant. (when looking at the particle by itself.) I mention the Cosmic microwave background because it is a universally uniform radiation that has a known average frequency, th... | [
"The CMBR is a thermal gas of photons with frequencies such that the temperature is ~2.7 K, this used to be higher but as the universe expands the gas cools. There is no connection between these photons and the meaning of electron orbitals. The typical energy between orbitals is on the order of electron volts ~1000... |
[
"Relative time question."
] | [
false
] | Disclaimer: I am a complete layman in regards to the matters I am inquiring. I am having problems with a rather unintuitive (for me) problem. Say for a moment that there are two inhabited planets, who's movement through space is a significant fraction of c relative to wach other. Two people, one on each plannet, perfor... | [
"The thing is, the two people don't have to agree on the order in which the events happened. Loss of simultaneity is one of the more important but also more complicated implications of relativity.",
"As to your followup question, the fastest gravitational system I know of, the Hulse-Taylor binary system, has obje... | [
"Yes, and relative to the center of mass of that system."
] | [
"Simultaneity is one of the coolest things about relativity. So if you're familiar that objects shrink in length when moving at speed, consider a barn and a pole vaulter.",
"The pole vaulter has a 10m stick, and the barn is only 5m long. If the pole vaulter is going fast enough, the pole will only appear to be 5m... |
[
"Can I make a non-mechanical battery powered by a saltwater gradient?"
] | [
false
] | This is not a 'practical' question. I'm just wondering if there's a way. | [
"Usually, concentration cells are built using electrodes composed of the metal that makes up the salt in question. If you were making, say, a copper sulfate concentration cell, this isn't a problem. ",
"If I understand you right, by saltwater, you mean sodium chloride in water. By analogy to my example above, ... | [
"I'd just like to point out that all batteries are non-mechanical. They all use chemical energy to make a current flow."
] | [
"I think some nordic country, can't remember which, built an experimental power plant which generates electricity through a saltwater gradient method. I believe i remember learning that it produces enough power to run a coffee maker...a whole power plant...one coffee maker.",
"Not much hope for a battery, im afra... |
[
"Is sleep's benefit effectively additive? And if not, how can I sleep through the night better?"
] | [
false
] | Most nights I'll sleep for six hours, wake up briefly, use the bathroom, and then sleep for another hour and a half. Is this basically as beneficial for me as sleeping for 7.5 hours (i.e., are the effects additive)? If not, what are some strategies for consistently sleeping through the night? Also, sleep cycles are gen... | [
"sleep cycles are generally 90 minutes, right?",
"This \"rule\" is completely overblown--it's an idealized estimate that has been taken out of context. The length of sleep cycles can vary considerably depending on the person, how much they've slept in previous nights, how tired they are, the presence of any nigh... | [
"I'm not an expert and I am just speculating here, but I think it would essentially be the same thing. Many animals engage in ",
"polyphasic sleep",
" and we can too. The uberman sleep schedule for humans involves multiple \"naps\" throughout the day and one can sleep for less total time and still get more REM ... | [
"I have a family friend who is a sleep researcher and his one sentence advice given at the end of his talks is \"sleep as much as you can, whenever you can\" (unless you are clinically depressed). The longer meaning is that you cannot sleep too much, you are only catching up on your \"sleep debt\", and it does not... |
[
"Why does salt in an open wound hurt?"
] | [
false
] | null | [
"Yes, but it would likely be from the highly exothermic reaction that would occur."
] | [
"Looking at it from an electrical engineering standpoint, it seems like this might be described as short-circuiting one's nerves."
] | [
"Looking at it from an electrical engineering standpoint, it seems like this might be described as short-circuiting one's nerves."
] |
[
"Wasp Sealing Own Nest?"
] | [
false
] | I have a wasp nest on my patio, it's a burrowed hole inside the wood that I have noticed a wasp or two flying in and out of in the past month. Yesterday I stood and watched this wasp sealing off the hole. It looked like a dried paste that covers the whole thing. My two questions are: What is the seal made of & why woul... | [
"They are sealing in their young. They will implant food and an embryo and seal it up to protect the baby till the baby can come out. It's sealed with the same thing the nest is made of - what that is I do not know."
] | [
"Solitary wasps use a diversity of materials in their work. The materials used are, however, species specific. Amongst the most common substances used are mud, conifer resin, silk, pebbles, and leaves.",
"They are fascinating critters in their own right; there are a large number of species. Some are poarasitic, s... | [
"I guess the main difference here is that although having one of these \"insect hotels\" will increase the number of wasps that are around, the individual wasps don't work together. Yes you might get one sting if you sit on one, but it won't trigger the whole nest to start swarming you. Solitary wasps are also su... |
[
"How do electrical grids manage phase balance?"
] | [
false
] | In the US most residences are fed by single phase power, usually via a split-phase transformer. Somewhere upstream of this transformer, presumably at a distribution substation, that single phase is being drawn from a three phase transformer. So what mechanism is used to maintain phase balance? Do you just make sure eac... | [
"In Australia (Victoria) when talking about single phase household connections we alternate through the phases per house as you go down the street.",
"This might lead to some imbalance but we also have smart meters at each property that give good usage data. ",
"When phase imbalance becomes enough of a problem ... | [
"What? No, not at all. Distribution service into residential homes is absolutely single phase to neutral. You have single phase lines with large step-down single phase transformers on them that take voltage down from between 12-14k volts down to 120-240 single phase/phase to neutral, then go through your meter t... | [
"I wish utilities would give households as clear an explanation for smart meter use as you have. So if you find one phase is being judiciously drawn upon by conscientious consumers and/or homes with grid- tied solar, you plop some of the high-usage pool heater/hot tub/ home welding shop/ Tesla-charging homes on to... |
[
"Has humanity exhausted any resources on earth? as in, its gone forever. (not species)"
] | [
false
] | [deleted] | [
"Would a plant species qualify?"
] | [
"We're doing a pretty good job of using up ",
" all of our ",
"helium",
". ",
"That's sorta close to exhausted. "
] | [
"Well not exactly what I was thinking but sure! That link was interesting enough."
] |
[
"Have spiders evolved to make their web near artificial light sources?"
] | [
false
] | There seems to be far more spider webs near lampposts and other artificial light sources. This makes sens since lot of flying insects are attracted by them and end up in the webs. I was wondering if this accumulation at these places is simply the result of spiders staying there because it works, or if there as been som... | [
"Attributing that observation to evolution would mean that there is a genetic change in spiders to cause it in which that change would be caused by natural selection against spiders that DON'T do that. I believe that is highly unlikely. Naturally, some insects are attracted towards those artificial light sources so... | [
"That's a genetic change that doesn't have mutation as a cause. Instead, the cause is a new set of selective pressures. The genetic population would become more red-haired and less blond/brown/black-haired. But it's just like your butterfly example (which I think you may have been remembering the ",
"peppered mot... | [
"I'm pretty sure it ",
" to involve a genetic change. In your example the butterflies with the beneficial color had them because of a genetic mutation."
] |
[
"What is exactly happening during muscle building? Google left me with \"jock\" definitions."
] | [
false
] | I have my bachelors in biology, but the most I learned about muscle physiology was in the introduction class. So I gather that growth of muscle happens from the cells in the myofibrils increasing in size and not number? That seems counter intuitive to me that you can have really big muscles that have relatively the sa... | [
"Firstly its important not to think of muscle fibres as conventional cells, they are many cells which have joined together to form a longer fibre with many nuclei and containing many fibrils composed mainly of actin and myosin. And yes it is getting more actin and myosin chains which increases your muscle size.",
... | [
"So working out doesn't create more muscle cells, just bigger ones? Is there any mechanism which creates more cells?"
] | [
"Useful link, but wikipedia tends to give you an \"explain it to me like I'm a third year college student majoring in this stuff\" fashion. That link is not very useful for a hobbyist who knows little about biology. "
] |
[
"What does the 3rd law of motion really mean?"
] | [
false
] | [deleted] | [
"It's related to conservation of momentum. If two objects collide and the momentum of each changes, the total momentum will still be conserved. That means the change in momentum that one experiences plus the change of momentum the other experiences will add up to zero. A force is just the change in momentum over ti... | [
"\"will the force from the truck to the sedan be equal to the force from the sedan to the truck.\" Yes.",
"Now, let's assume that both vehicles are perfectly elastic (not realistic, but relevant for this discussion). The sedan will bounce back much faster than the truck, since the truck is heavier. Therefore, ... | [
"mph is a unit for measuring speed, not acceleration. The equation F = ma uses acceleration."
] |
[
"Why is 90% sulfuric acid more corrosive than 99% sulfuric acid?"
] | [
false
] | I tried doing some research on this but the only reason I can find that explains this is that 90% acid has a higher water content. However, that is not too clear to me why the extra water content affects corrosion. | [
"The applicable definitions of acids refer to their ability to produce H+ in solution or to donate H+. They can only do that when they are in solution, i.e. dissolved in water.",
"The water allows for dissociation of the proton, H+, yielding H+ and HSO4-. It's the H+ that does the work of corroding metals and rea... | [
"Yep. But when you're talking about chemistry, you usually put things in terms of elements rather than fundamental particles."
] | [
"H+ (hydrogen ion) is a proton in the physical sense and is also oftentimes refered to as a proton in chemistry (for example, acids and bases being refered to as proton donators and acceptors, or the process of protonation and deprotonation). However, in practice hydrogen ions like that are unstable and form bonds ... |
[
"It is reported that redheads, with their mutated MC1R gene, require about 20% more anesthesia than the average person. Are there other reported correlations between this gene and other effects (pain tolerance, drug tolerance, metabolism, etc...)?"
] | [
false
] | null | [
"Lots of relationships with this gene: ",
"https://monarchinitiative.org/gene/HGNC:6929#phenotype",
" (see also tabs for related diseases, interactions with other genes, etc., and the support drop-downs linking to relevant publications)."
] | [
"Surgical nurse here....I would say bleeding. I even once had a (very good) surgeon that was frustrated with a high blood loss case kinda curse out \"Goddammit she's not even a redhead!\" I piped in- \"She had 3 daughters in pre-op, all flaming red heads.\" The whole OR went, \"ah, that explains it!\" ",
"This i... | [
"Surgeon here, not an anaesthesiologist",
"You can’t know for sure that it’s ",
" of one particular gene. That’s impossible to say. It will depend on what drugs they were using (and specifically how these drugs are metabolized—some people metabolize some drugs faster than others), what prior exposures you’ve ha... |
[
"Where in the scientific process does consensus break down?"
] | [
false
] | I apologize if I'm oversimplifying the issue. My understanding of the scientific process is that as new evidence is found, it viewed through the established theory. If theory holds up, it is expanded to include the new evidence. However, if the evidence seemingly contradicts theory, then it is necessary to re-evaluate... | [
"Most of your question is closer to philosophy of science than straight science. You may want to read Kuhn's \"The Structure of Scientific Revolutions\" which discusses many of your questions in detail.",
"Shouldn't an evidence-based approach lead to the same conclusions by everyone who sees the evidence?",
"A ... | [
"First of all, consensus is not really an important part of scientific theory. Science isn't done by polling and individual results should stand for themselves.",
"The question of consensus therefore often concerns not so much individual results but their interpretation. A prominent example are quantum effects in... | [
"Wait, what are you referring to? I honestly don't know. (For the bystanders, I'm the other author.)"
] |
[
"Do sound follow inverse square law? Like light and gravity?"
] | [
false
] | null | [
"The intensity of a sound wave from a pointlike source goes like 1/r",
"."
] | [
"That's inverse square law if r denotes distance"
] | [
"Correct."
] |
[
"Whats the difference between a 30p pack of own brand aspirin(or any over-the-counter drug) and £1.30 pack of named brand?"
] | [
false
] | both are 16 pack of 300mg aspirin Is the more expensive better refined? or are you literally paying for a name? | [
"£1"
] | [
"Nothing. They might even be made in the same factory."
] | [
"Generic medications are required by law to have the same amount of active ingredients as the brand name medications, so for most things there is no benefit for paying extra.",
"The only exception is for formulations that have very low API ratios - like antidepressants and a few other types of medications. Becau... |
[
"[Physics] What happens to kinetic energy when car stops?"
] | [
false
] | Hi Reddit. Me and my friend had an angument about where kinetic energy go when car breaks. He says energy completely transforms into heat energy of break pads and then transmits to the air. I say only a small portion of energy (like 5-10%) transforms into heat and most of it is transmitted to the Earth, so when car sto... | [
"almost none of the energy goes into rotational energy of the Earth.",
"I'll use linear momentum instead of angular momentum (because you also do expect the car to give the earth linear momentum), but the conclusion is the same.",
"From conservation of linear momentum:",
"M v_E = m v_C",
"where v_C is the o... | [
"Heat, sound, and vibration. Mostly heat not necessarily to the air but the friction caused by the braking action heats up to brake discs. That's how they warp over time too. When I drive through water and brake the metal heats and cools unevenly. "
] | [
"To add to this, modern hybrid cars recoup some of the car's kinetic energy when the car brakes and feeds it back into the battery to make the car more efficient. If the energy went to the earth, the hybrid cars would not be able to do this."
] |
[
"Does the physics of \"shock dynamics\" check out?"
] | [
false
] | I've recently stumbled upon this site . The website presents evidence for an alternative to plate tectonics, namely an impact generated continental drift. There are even calculations concerning the kinetic energy of the astroid to make such an impact happen. Can anyone tell me if this scenario is plausible? | [
"No. This is........ I haven't heard of this theory before, but of all the theories concerning a rebuttal of plate-tectonics, this is the most asinine, poorly thought out construct I think I've had the misfortune of reading. ",
"This can be refuted in one simple fact: If there was an impact that big, don't you th... | [
"I was just wondering if it's a plausible theory. Even if we don't have any evidence for it, can it even have the smallest chance of happening?"
] | [
"no, it's not plausible. The geodyanamic record is really quite good in the broad understanding, it's just the details and smaller details of mechanics that need to be worked out. There is no way this theory could account for 99% of the phenomena we see in plate tectonics. ",
"There is absolutely no way this is a... |
[
"Were there changing seasons at all during the ice age, or was it like a long, harsh monotonous winter?"
] | [
false
] | null | [
"It would have depended on your latitude. Generally speaking, an Ice Age simply means the average global temperature was lower than normal. Near the equator, you would have still experienced seasons, but in the more northerly regions, the temperature was low enough that there was ice year or snow year round."
] | [
"Just to add, I believe we are still in an ice age. We are in an interglacial period. In other words: colloquial use of ice age = interglacial for climatologists.",
"In a true non-ice age, there is land vegetative life at the South Pole and a very different overall climate dynamic due to orbit, axial tilt, and ot... | [
"Yes, there absolutely are seasonal cycles during glacial periods. ",
"In fact, at some times the seasonal cycle was actually ",
" than at the present day. The seasons are controlled by Earth's obliquity, which is the tilt of the planet's spin axis relative to the plane of its orbit. The steeper the tilt, the g... |
[
"Why would animals share self-harming information?"
] | [
false
] | I read that dogs have anal glands that release smells which give information to other dogs about their health. So other dogs can decide if they would want to make acquaintance but wouldn't natural selection make it so that all dogs would give out 'good' smells even if they were unhealthy just to get a chance to reprodu... | [
"Aside from what others posted, animals do occasionally indeed try to share evolutionary advantageous information, and mask the self-harming one, known as ",
"dishonest signals",
". For example, it was observed that shorter bears get on their tiptoes to rub their fur against trees, creating the illusion that th... | [
"TLDR: Any signal that can be faked can reasonably be ignored.",
"This is a great question and demonstrates some good thinking about evolutionary theory! If organisms can increase their fitness by deceiving others, why would they give honest information, especially honest negative information?",
"Some people ma... | [
"So let's say an unhealthy dog gives off a good scent. Then that dog mates. So that dog either dies before giving birth, or if it does give birth, it cannot care for it's young, and has either few offspring or sickly offspring that do not fair well in life. Meanwhile, a healthy dog gives off a bad scent. That do... |
[
"what would happen if we dropped at bowling ball from the same height as the stratosphere jump? would it make a small crater?"
] | [
false
] | like i said in the title if we were to drop a bowling ball from the same height as the stratosphere jump would it make some kind of crater. what if we tried the same thing with a pumpkin. | [
"Both objects would reach terminal velocity quickly, and continue hurtling toward Earth at that speed. Terminal velocity will be higher at higher altitudes, but as they fall into more dense air, they will slow slightly.",
"For a sphere, terminal velocity = (2mg / CρA)",
" , where m = mass, g = gravitational ac... | [
"Very minor but you meant 27\" circumference instead of diameter."
] | [
"Good catch."
] |
[
"Why don't we withdraw from exercise but withdraw from drugs?"
] | [
false
] | I understand that both drugs and exercise block neurotransmitters. In , Huxley writes that mescaline acts like depleting sugars in our brain. This gets us high. He types that it compares to running. I doubt we withdraw from mescaline, but I know that we withdraw from opiates and some stimulants. Do we withdraw from dru... | [
"This assumes that we don't, in fact, feel a sort of withdraw when we suddenly stop exercising. However, many people feel irritable when they don't get the workouts to which their bodies have become accustomed. ",
"Taken from: ",
"http://www.livestrong.com/article/364106-what-part-of-the-body-does-skipping-exer... | [
"In Doors of Perception, Huxley writes that mescaline acts like depleting sugars in our brain. This gets us high.",
"That aside, withdrawal from drugs is caused by your body being accustomed to the presence of something and down/upregulating things based upon whatever the presence of that something causes.",
"F... | [
"This is a good point; I don't know why I romanticized exercise and demonized drugs. Maybe this means our brains react to these stimuli in a similar way? "
] |
[
"Will the universe ever reach a point at which entropy cannot increase?"
] | [
false
] | This question occurred to me in a thermodynamics class. | [
"http://en.wikipedia.org/wiki/Heat_death_of_the_universe"
] | [
"Follow-up question: if entropy is no longer increasing, would time essentially cease as well? If there was no longer any change in the system, whether towards higher or lower entropy, then there would be no way to measure the passage of time."
] | [
"It's not necessary that total entropy in the universe increases, only that it doesn't decrease. Notice I say total, because it is possible for entropy to decrease locally. But as far as the universe(the system that is defined as the system that contains all other systems) is concerned, entropy cannot decrease. ... |
[
"How did aboriginals make it to Australia (Sahul)?"
] | [
false
] | null | [
"there was no water inbetween, New guinea and oz were walkable, the sea level was much lower then before the end of the last ice age. The continental land mass was called ",
"Sahul"
] | [
"Island hopping. There's no reason not to assume that humans didn't have rafts or canoes that long ago. It may not have even been intentional: it could have been as simple as coastal fishermen getting swept out to sea by storms and winding up at sahul.",
"Interestingly, there was still intermittent contact betwee... | [
"But how did they get to Sahul in the first place?"
] |
[
"If there were no moon would we have waves?"
] | [
false
] | I know the moon causes the tides, but without the moon would there be no waves as well? I suppose a different way of asking this would be to say do the tides cause waves? | [
"The moon only causes the tides, the waves are a result of the chaotic conditions of the atmosphere (like wind, as Organic_Mechanic mentioned) and other fluid mechanical processes.",
"(Source: I am an astrophysicist)"
] | [
"Waves are a product of wind currents hitting the water (mostly) and thus would still occur. Ever notice how its wavier on the water when it's windy outside as opposed to when there's no wind (see: a nice sunny day)."
] | [
"Indeed, I have noticed this. I also just noticed that there were still waves on a day with no wind (I just moved to the beach). Just wasn't sure exactly which forces were in play. Thanks for the response!"
] |
[
"How did humans evolve to be able to accomplish extraordinarily complicated tasks?"
] | [
false
] | building complex objects (cabinetry, a PC, a car's transmission); training to perform non-intuitive actions (driving a race car, typing words as quickly as they're spoken, painting); et cetera. None of these actions have conveyed an evolutionary advantage upon the actors for any significant period of time. Obviously th... | [
"Tool building and use? I mean that's what a lot of this boils down to. How does this thing work? How can we make it work better? That's my guess at least. I too have wondered though about driving. That does seem really interesting that we can move around at tens or hundreds of miles an hour and still be able to p... | [
"You seem to be talking about two different things. First you talked about building complex objects/machines, and then you talked about having good motor function with respect to your body. ",
"None of these actions have conveyed an evolutionary advantage upon the actors for any significant period of time.",
"I... | [
"In terms of the brain, we evolved to be pattern matchers. We learn by noticing specific patterns of behaviour, and by comparing them with the patterns we have already stored. That comparison allows us to suss out the differences between one thing and another, eventually creating distinct mental representations o... |
[
"What happens when you compress water?"
] | [
false
] | I hear a lot that water is incompressible. But it must to some degree. Hypothetically if you take the mass of two planets and make them collide with a litre of water in the middle, what would happen? When people say water is incompressible, I take it as such. Can a litre of water really support two planets? Seems too f... | [
"You don't need to collide two planets to compress water. You can just put it in a pressurized chamber, or go to the bottom of the ocean.",
"Water is incompressible for most engineering applications, but it definitely compresses. It compresses by about 2% at 4 kilometers under water. If you put it under more extr... | [
"Or you could use a ",
"diamond anvil cell",
" and compress up to 300 GPa. At these pressures water becomes Ice X (except at very, very high temperature), with a density of 2.51 g/cm",
" , meaning a compression factor of 2.5.",
"Water is predicted to transition to a metallic state somewhere in the 2-5 TPa ... | [
"I hear a lot that water is incompressible. But it must to some degree. ",
"Water is compressible, but is very difficult to compress. The fact that sound travels through water in the same way it travels through other liquids and gases (compression waves) is evidence that water is possible to compress.",
"The co... |
[
"What is meant when astrophysicists say that the universe might be \"saddle-shaped\"?"
] | [
false
] | I've often heard that the universe night be spherical, flat, or saddle shaped, depending on it's total mass. What is meant by this? Why would this happen? Why would a flat or saddle shaped universe mean infinite volume? | [
"The terms \"flat\", \"spherical\", and \"saddle shaped\" (I prefer Pringles shaped) are meant to be ",
"; they're two-dimensional examples of the sort of curvature that our three-dimensional universe could have. To say that our universe is \"flat\" is to say that it is uncurved—that, for example, the interior an... | [
"From what I understand if the universe is spherical(ie we exist on the membrane of an expanding bubble), it would be very very massive. Trillions of light years to make it all the way back to the starting point. And the traveler would have to be moving faster than the speed of light to ever accomplish even one go ... | [
"On a 2D surface, there are the terms \"flat\", \"spherical\" and \"saddle shaped\", but 3D space, are there more types of different curvatures?",
"(For example, on a 1D line, there are only spherical (circular) and flat, once we go into 2D surface it can become flat, spherical, and saddle shaped, once it's in 3D... |
[
"Is the rate of our expanding universe exponential?"
] | [
false
] | Or is it more of a gradual, linear type of expansion? For example, using miles per hour as a speed measurement. Is the universe accelerating like this: 1mph->2mph->3mph->4mph->......... or is the universe accelerating like this: 1mph->2mph->4mph->8mph->16mph->......... Bonus: Does that mean the universe was a certain s... | [
"For the last little while - the last 4 or 5 billion years - the universal expansion rate has shifted from deceleration under the influence of matter, to acceleration under the influence of the dark energy.",
"You can think about it like this: if most of the energy density in the universe is in the form of matter... | [
"There is one technicality that makes the answer \"yes, the expansion of the universe is exponential\" not quite correct, and you touched on it (and probably you are already aware of it, but you just take it for granted):",
"What you get from this is that the fractional rate of acceleration (that is, the rate of ... | [
"Interesting, I've never heard of the density of dark energy explained as a constant before. It makes sense if the density is, in fact, constant. Thank you for the explanation!"
] |
[
"Does masturbation have any effect on mood, confidence or personality?"
] | [
false
] | null | [
"Some of it:",
"\nA lot of it has to do with the chemicals released after ejaculation: \"men release a cocktail of brain chemicals, including norepinephrine, serotonin, oxytocin, vasopressin, nitric oxide (NO), and the hormone prolactin\". ",
"ref",
". These chemicals make us sleepy afterward.",
"\nSo doing... | [
"I have a quick (related) question: Would frequent sex have the same effect as frequent masturbation? I mean, surely there isn't a difference in the type of orgasm (ie masturbation vs. sex) for a male since orgasm is typically reached the same way for each. As a female, though, I have no idea how it feels for a ... | [
"The hormone prolactin is actually 4x the amount after sex than it is after masturbation. Mix that with the full-body physical activity of sex which as a work out brings out its own chemicals... "
] |
[
"Is there an anatomical reason Chicken Pox scars form where they do?"
] | [
false
] | null | [
"Your premise is probably wrong: The face in general ",
" be slightly over-represented as a place for chickenpox scars, but not by much. Only about 20% of children with chickenpox ended up with scars, and of those fewer than half had scars on their face; nearly 60% had scars on their abdomen. ",
"The scars were... | [
"I’m old enough that I got pox partied (36. If you were the first in the mom group to get chickenpox, you got a bunch of playdates with all the kiddos that hadn’t had it yet). I REMEMBER being absolutely covered, I’m talking like at least four in a square inch. Anecdotally, I have zero scars.",
"Mine was not too ... | [
"Does every lesion lead to scarring though? Or is just where the person has excessively scratched and irritated it? Or is there some other factor?"
] |
[
"Why is the inverse of operations not as \"neat\"?"
] | [
false
] | For example, adding natural numbers keeps the answer a natural number, but subtraction runs into negative numbers. Multiplying numbers doesn't run into problems, but division runs into problems with dividing by 0. Exponentiation also doesn't have any problems, but rooting can run into imaginary numbers. Taking the deri... | [
"Because functions are by definition total and single-valued but not necessarily injective or surjective. If you start with some function on a particular domain, then by definition the function takes every point in the domain and produces an output and furthermore it produces a single output. However, it does not n... | [
"Addition is the inverse of subtraction, but addition is neater. Of course one would typically think of it as the other way around, but it seems reasonable to think that addition appears to be logically prior ",
" it is neater and requires less structure.",
"Taking the derivative of a 2-variable function pretty... | [
"Integration is actually a lot \"simpler\".",
"Indeed. I think a lot of the confusion here stems from underappreciation of the fundamental theorem of calculus. Fundamentally, an integral is limit of sums of areas of rectangles (just sticking with the Riemann integral for now). There's no a priori relationship bet... |
[
"Is it possible for there to be a room whose walls reflect no light? So that even if we shone a light the walls reflect nothing and it appears that there is nothing but darkness?"
] | [
false
] | null | [
"Theoretically, yes. However, there are no materials known to man which have a optical absorptivity of 1.0. Now you have to ask yourself what you mean when you say \"no light\" - do you mean \"No light that I can see\" or \"no electromagnetic radiation at all\"? ",
"If you mean \"no light that I can see\", the... | [
"Ab absolutely fantastic answer, it's well written and explains easily what I had asked. Thank you very much good sir! "
] | [
"Even when it's \"cold\" it's still releasing radio or infrared waves. ",
"Is there a cutoff where it stops releasing infrared waves and switches to radio. Is that cutoff at 0 Kelvin?",
"It is just strange to think about how all throughout the radio spectrum you use electricity to send radio waves, however the ... |
[
"Does having smart parents mean you will smart? Does having dumb parents guarantee you will not be smart? And does being musically gifted mean you could be mathematically gifted, \"if you applied yourself\"?"
] | [
false
] | I had an interesting conversation with my Uncle last night. We were discussing the ability to pass on "raw intelligence" through your genes. "Whether it be artistic ability or mathematics", he argued, "it makes no difference; they are both the same: exacted potential." He claims, while being completely unmusical, that ... | [
"I'm a Ph.D. student who does a lot of research on intelligence. I agree with much of what you say, but I'd like to counterpoint other things:",
"Personally, I don't like Gardner's idea of \"multiple intelligences\", such as Spatial,\nLinguistic,\nLogical-mathematical,\nBodily-kinesthetic,\nMusical,\nInterpersona... | [
"Intelligence is partly hereditary, and partly due to the environment. There are genetic components to how our brains work, but at the same time our brains are responsive to what they're put through, well passed childhood - we have a fairly high degree of neuroplasticity. ",
"So dumb vs smart parents won't alway... | [
"According to most studies, general cognitive ability is about 75% - 85% heritable by the time you're 18. During childhood things are a little less predictable, because environmental factors probably play a bigger role in the earlier years. By adulthood, there is a very strong correlation though. Here is a good ... |
[
"Why are the other apes so much more stronger than us?"
] | [
false
] | The fact that the Gorilla is so much stronger than man seems obvious by appearance, though I am sure there may be more to it, but even the average Chimp or Orangutan seem to exhibit raw strength that competes with even the most elite strength athletes. Why are they so strong? Also, why did we not retain this strength? ... | [
"Several possible reasons:",
"1) Other apes live more active lives than we do. A particularly fit human who lifts a lot is obviously going to be much closer to other apes.",
"2) We left the trees.",
"3) We have much better fine motor control than other apes. It's hypothesized that this is due to a change in... | [
"Can you expand on the change in muscle architecture?"
] | [
"tl;dr: Leverage."
] |
[
"Does an electron jump back down from it's excited state to it's initial state spontaneously or is there a definite interval involved before it jumps back down?"
] | [
false
] | null | [
"If you prepare an atom in some excited state, which decays to the ground state (assuming a two-level system for simplicity), the state vector of the combined system of the atom and electromagnetic field evolves with time into some superposition of |excited atom>|no photon> and |ground state atom>|1 photon>.",
"T... | [
"The decay half-life is an intrinsic property of the decaying state. So every atom of the same type, prepared in the same state, will decay according to the same probability distribution as a function of time. It is proportional to e",
", where the k is the same for all of the atoms. "
] | [
"You are mixing two different things here.",
"The Eigenstate is also undeterminable",
"Which eigenstate of what?",
"and so start point and ends points for a decay over a period of time are impossible to calculate and therefore it is indeterminable whether or not the decay rate is constant or variable and we c... |
[
"How do droughts occur? If water is conserved in the water cycle, where does the rain that would normally fall go?"
] | [
false
] | For example, the drought in California means that less free water is available for use. Where did this water go? | [
"The water goes somewhere else, in accord with prevailing weather patterns. California is in a drought right now because the jet stream keeps bypassing the west coast and going across the US instead. There has been quite a lot of flooding in the northeastern quadrant of the US lately, and southeastern states are no... | [
"So then theoretically, the jet stream could return to California in full one day?"
] | [
"Yes, and possibly soon. Climate scientists were ",
"looking for an El Niño this year",
", which could pull the jet stream down the coast and bring rain. Now they're not so sure it's going to happen, and if it does it might be too weak to do much good."
] |
[
"What causes objects in the distance to be less vibrantly colored than those nearer to the observer?"
] | [
false
] | On my way to work this morning, I finally put some thought into a "phenomenon" that I see every day. The trees just 20 feet ahead of the car were a beautiful, deep green. But the trees more distant, say a mile ahead, were quite bland and visibly less green than the nearer trees. Now, my best guess for this is because o... | [
"Indeed. That is why we can see the colors of the stars, even though they are so far away, and determine what they are made of :)"
] | [
"The answer is dust, my friend. It absorbs all of the deep, pretty colors and reflects dull grays and browns. There are some other things that cause this too, other than particles, like the molecules in the air itself (to a lesser degree)."
] | [
"Alright, that makes sense. I hadn't even considered particulate matter."
] |
[
"Why is there such a thing as \"critical mass\" for a radioactive material? Why couldn't the chain reaction sustain itself with less mass than the critical amount? How is this mass calculated?"
] | [
false
] | null | [
"Fission results in the release of 2 to 3 free neutrons. To sustain a critical chain reaction, on average, one of these neutrons should be captured by a fissile nucleus and cause it to fission.",
"So what you need to understand is the parameters that affect how likely it is for a free neutron to be captured in th... | [
"Not a problem. If anyone is particularly interested an excellent and surprisingly digestible publication is ",
"Anomalies of Nuclear Criticality",
"."
] | [
"Wow, that response was awesome! Thanks for taking the time to type it out"
] |
[
"Slow moving asteroids?"
] | [
false
] | When we see or hear about asteroids they are always racing through space at crazy speeds. Is it possible that we would someday encounter a slow moving asteroid, that simply landed on earth quietly? | [
"Suppose that there is some asteroid that's more or less still in relation to Earth. Then it's set on a collision course with Earth, but at a very slow speed, again in relation to Earth. This is more or less the same as dropping a big rock to Earth from a great height. Even though the rock initially is still, it'll... | [
"It depends on definition of \"slow\" you have. Short answer is No we won't encounter an asteroid which simply landed quietly, Earth gravitation will attract it and it will gain speed."
] | [
"Asteroids are typically in orbit around the sun. Their orbits are generally elliptical. In order to stay orbiting the sun, they have to have a specific velocity. But that velocity at the outer most point of their elliptical orbit is relatively slow, and it increases as the asteroid approaches the closest point of ... |
[
"What's the difference between clinically diagnosed depression and that which comes about due to a life changing event (death, breakup, misfortune)?"
] | [
false
] | Have dealt with depression from a clinical standpoint, but I was just thinking about a time when a friend was explaining to me how he was feeling after a breakup. The way he described his emotional state, it really fit the general idea of depression. Looking back I was a bit of a dick towards him at the time because it... | [
"Grief is a relatively healthy, adaptive reaction to loss. While significant loss typically triggers a normal grief reaction, it can also trigger a Major Depressive Episode (MDE). The DSM-5 points to key differences between grief and MDE. Grief comes in waves and usually mixed with pleasant emotions/memories, where... | [
"By what criteria do they decide on those exclusions? Seems rather arbitrary to me."
] | [
"From what I gather, much of the criteria is based on how long these symptoms have been present, usually defined in either multiple weeks or months."
] |
[
"If I spin a marble on a smooth surface, it appears to slide along the plane. Is it rolling, is it actually sliding?"
] | [
false
] | I have a marble and I set it spinning horizontally to the desk. The desk is slightly out of level. The marble will move towards the lower part of the desk while continuing to spin. If the marble wasn't spinning it would roll along this plane, but when it is spinning, it appears not roll, it looks like it is sliding. ... | [
"Yeah, it can slide/skid. See how a ",
"bowling ball moves",
" for an example of both sliding and rolling."
] | [
"A bowling ball is also on top of a layer of oil."
] | [
"It should be \"sliding\" because the angular momentum generated by spinning the marble will create torque that resists the molecule turning outside of the direction of its spin."
] |
[
"Why does it take more energy to use muscles that have been worn out?"
] | [
false
] | [deleted] | [
"Muscles have a given store of glycogen(a polysaccharides, meaning a large molecule of sugar), which is the animal equivalent of starch-an (almost) ready to use energy source. After the blood glucose is used up-within seconds of all out sprinting, or a few minutes of normal running this is the primary source of ene... | [
"Well, no. It still takes the same amount of ATP, it's that there's less free ATP available because the muscle has switched to a less efficient energy source. Thus peak muscle force is less. "
] | [
"Well, no. It still takes the same amount of ATP, it's that there's less free ATP available because the muscle has switched to a less efficient energy source. Thus peak muscle force is less. "
] |
[
"My car has a display showing the gas consumption (MPG or Litres/100km) for the current moment and the current drive so far. Is it physically measuring the gas consumption, or is it monitoring other parameters to calculate gas consumption?"
] | [
false
] | null | [
"On new cars, it's done by calculation, using the commanded fuel injector pulse width and your current speed. There are also dial gauges that were used about a decade ago that were less accurate and used engine vacuum as an indicator."
] | [
"OP said \"physically measure\". To me, this implies some sort of meter on the fuel line. ",
"Monitoring pulse width and other variables is calculated because you're not directly measuring fuel flow. "
] | [
"That is a measurement of what the fuel flow ",
" be, but the actual flow may vary slightly from that."
] |
[
"Have we reached the optimal compression rate for data?"
] | [
false
] | Feels like there haven't been any major enhancements the last years when it comes to data compression. Are we restricted by physical laws or is it just really hard improving it? Is the next logical step improving e.g bandwidth/computational power etc as a way to lessen the gap? | [
"Video compression is arguably still improving. The ",
"daala codec from Mozilla and Xiph.org",
" is a totally new and fundamentally different approach (so that it will not be subject to patent claims).",
"Daala is a new general-purpose video codec currently under development at Xiph.Org. Our performance targ... | [
"Replying to myself: The ",
"Opus audio codec, also from Xiph.org",
", is a relatively new audio code that also used a new approach, and it achieved an ",
"unexpectedly good result in that it is now the best audio codec to use in all applications",
", which is performance beyond its original design aims.",
... | [
"I can fully describe to you what I read last night by saying \"I read Bartleby, the Scrivener\", but the Kolmogorov complexity of what I read last night is much higher than that.",
"Not necessarily. The ",
"invariance theorem",
" tells us the Kolmogorov complexity of the book you read is only an upper bound ... |
[
"Does a hot object in a vacuum with an emissivity gradient self propel?"
] | [
false
] | Imagine a spherical object with mass existed in empty space with no other mass, with the object initially at rest. If this object has one side of it with a higher emissivity than the other side, and it is at some non zero temperature, will it self propel due to its radiation being biased to one side? | [
"Yes, until the object cools down to the temperature of its environment.",
"Not purely from emissivity differences - temperature differences played a role, too - but the ",
"Pioneer anomaly",
" was caused by radiation pressure."
] | [
"Yes, and it happens for asteroids. Since they are heated on one side and are rotating, this effect can slightly change their orbits. This is known as the Yarkovsky effect."
] | [
"If you're doing this on purpose it is called a photon rocket. Light has momentum but you have to radiate about 300 megawatts of heat to produce 1 Newton of force. ",
"If an asteroid is doing it accidentally it is called the ",
"Yarkovsky effect.",
" The sunny side of an asteroid is hotter, and most asteroids... |
[
"Can the Covid-19 pandemic turn into something similar to the 1918 Spanish flu? Behaviourally, not severity."
] | [
false
] | I've been reading a lot about the historical pandemics of late when I stumbled upon the Spanish flu. Like Covid-19, its first wave predominantly effected the elderly but when it came back during the fall, more strongly, it mainly effected healthy young adults and that period is considered the deadliest of that pandemic... | [
"It’s hard to compare today’s pandemic with 1918 for obvious geopolitical reasons. There was a world war, widespread hunger, and modern medicine was in its infancy. Most deaths were caused by bacterial pneumonia, which often follows flu infection, and antibiotics were still a few decades away from being discovered.... | [
"The virus is extremely unlikely to mutate into a more or less severe disease. It has a very low mutation rate and no mutations thus far have appreciably affected disease severity. That said, less severe disease causing virus would be selected for if anything, since healthier hosts can spread virus to more naive ho... | [
"Like I said, extremely unlikely. Viruses with a high mutation rate tend to be “metastable” because they are at an evolutionary peak and so most mutations are neutral and steps away from the reference genome either die out or revert back. ",
"This one has a low mutation rate. There is very little chance there wil... |
[
"If you flew towards a black hole at velocity V from a point in space, and then turned around and flew back to the point at 2*V, at any point during that trip would you be able to see an earlier version of yourself?"
] | [
false
] | [deleted] | [
"shouldn't the time it usually takes light to reflect off you towards the start point appear to take longer and longer?",
"No, light always travels at c regardless of gravitational / velocity components.",
"You are always traveling slower than light as it leaves your current position, what you are proposing wou... | [
"No. The short version is that in order for that to happen you would, at some point, need to exceed the local speed of light.",
"The longer version is easier to consider if we look at an alternative formulation, where you are carrying a flashlight and flip it on and off at some point. Then the question becomes, i... | [
"Ah, thanks for the prompt response!"
] |
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