title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How is the result \"1+2+3+4+...=-1/12\" used in string theory if it's based on a faulty proof?"
] | [
false
] | [deleted] | [
"My apologies but this is a hard question to answer without some analysis, I hope it's understandable, I've tried my best but it goes pretty deep.",
"This question rests deeply on what kind of limit you are using to evaluate the sequence. They are using an unusual sort of summation so it seems weird.",
"So what... | [
"There is a commonality between the way the \"faulty proof\" works and how the field of physics that uses it works. ",
"In the faulty proof, we are dealing with infinite series that either diverge by going off to infinity, or just don't rest at a single value (1-1+1-1+... just alternates between 1 and 0, never ge... | [
"Basically, the video is arguing for the right thing with the wrong arguments, in particular due to oversimplification. The proof is bad, and it should feel bad.",
"In particular it's worth noting that the right-hand side (\"-1/12\") and the left-hand side (\"1 + 2 + 3 + ...\") are not equal, but both of them rep... |
[
"Why haven't suits been created to withstand a crazy amount of radiation?"
] | [
false
] | null | [
"Because walking around with hundreds of pounds of lead shielding on you is not practical.",
"A Faraday cage only stops electromagnetic radiation with wavelengths at least on the same order of magnitude as the grid spacing. You can't make a Faraday cage for gamma rays."
] | [
"So granted im going with the dentist chair idea here. Is that how much it would take? Hundreds of pounds of lead?"
] | [
"The thing you wear at the density is for x-rays, but you’ll need even more for gamma rays.",
"How much you need depends on how safe you want to be. But there’s a reason why we don’t do this: because people have thought about it, and it’s not practical."
] |
[
"Need help identifying a rock I found when I was very young, which glowed when I struck it"
] | [
false
] | [deleted] | [
"Wouldn't have been quartz, would it?",
"http://www.youtube.com/watch?v=eLkIoB5Iv5o"
] | [
"I'm puzzled by this rock - you do not appear to be describing a simple sparking process, but more of a kind of glow. Sounds like a mineral property called triboluminescence. Several minerals can display this behaviour and it is not sufficient onto itself for identification. Any chance this could have been in the g... | [
"Does this happen because quartz has piezoelectric properties? If not, how would you explain why it produces sparks?"
] |
[
"If by chance we could make it to the Moon and build structures, would we be able to build larger building on the Moon then here on Earth because of the Gravity?"
] | [
false
] | just talking to my genius friend who is a med professor at wash u. talking about Cosmos series done by BBC. this question came up | [
"Yes, in fact there is an idea to build giant radio telescopes etc on the moon because you could build them at a much larger scale than on earth, and on the dark side of the moon to block out signals from the earth."
] | [
"It's called the Lunar Array for Radio Cosmology (LARC). Here's an ",
"article",
" about it."
] | [
"Taking gravity alone into effect, you could easily build mile-high structures, but I suspect things like solar and cosmic radiation and asteroid impacts would make underground mega-structures far more appealing. Also, tall buildings here tend to be pretty narrow, and you'd probably want better surface to volume ra... |
[
"Why can we measure the diameter of a proton but not an electron? Do we have any proof that the electron has size rather than being a point particle?"
] | [
false
] | null | [
"Electrons are elementary particles, so the Standard Model treats them as pointlike. We have no reason to believe that electrons have any spatial extent. However protons are composite particles, so they have a meaningful radius, which can be measured."
] | [
"At one point we did think the proton was pointlike, but experiments at Stanford’s Linear Accelerator showed otherwise. We can make predictions for electron scattering from a pointlike proton but the SLAC data showed deviations from this. As Robus says, since the proton is now known to consist of smaller (pointlike... | [
"Thanks for the help!"
] |
[
"After a vasectomy, where does the stem go after an ejaculation?"
] | [
false
] | [deleted] | [
"Sperm only constitute 2 to 5% of total semen volume",
". The remainder of the seminal fluid is still expelled from the body during ejaculation.",
"Your body will recycle unused sperm cells that reside in the testes. As new sperm are generated, old sperm will be broken down and their component nutrients recyc... | [
"The vas deferens tubes aren't just left open after the procedure, the ends are cauterised for two reasons, firstly so that the sperm can't leak out, and secondly so that the ends don't come together at a later point and heal, reversing the vasectomy by itself. "
] | [
"The tubes are closed off. So, the ejaculate doesn't end up in the scrotal sack.",
"You are wondering what happens to the buildup? The same thing that happens to a person who doesn't masturbate or ejaculate for a while, it just gets absorbed back into the system. "
] |
[
"How fast does the small metal ball at the end of an average pen spin when you're writing?"
] | [
false
] | When I was writing notes for classes, I became curious as to just how fast that little ball is rotating in the tip of the pen I was using. I have no idea how to calculate it and I haven't found an answer, so I was wondering if anyone knew. Just for example, say the pen is an average .5 mm rollerball and you're writing... | [
"Assuming perfect grip, so 1cm on paper is 1cm on the ball surface:",
"\n.5mm (assuming diameter) gives a circumference of .5(pi)mm or around 1.6mm.",
"\nFor 1cm travel this translates to 10mm/1.6mm rotations per second which is: 6.25 rotations per second, although I think 1cm travel per second is an underestim... | [
"Whilst I can't make a reasonable estimate of the grip (although I imagine it would be close to 'perfect' since the flow of ink is uninterrupted), The ball would be rotating even on a wavy line. The angle of the pen is irrelevant since the ball is 'free floating' effectively. Just imagine a giant exercise ball roll... | [
"I think they meant fast, not fat"
] |
[
"The impact if our moon was an icy body."
] | [
false
] | With the surface and albedo differences between our earth and the moon, I calculated that, if our moon was an icy body like Europa, 6 to 7 times more light would be reflected to earth then our moon does during the perfect full moon, which would come down to about 10-13% of the light that arrives from the sun directly, ... | [
"Not 100% sure what you're asking, but maybe I can help clear some things up:",
"The sun is about 400,000 times brighter than the moon. If Earth's moon were as bright as Saturn's moon, Enceladus, which has an albedo of .99, ",
"This would have no impact on our climate, but it would make nights much brighter, w... | [
"Using the word \"impact\" threw me off for a while.",
"This is a neat question, I'm interested in seeing what the night time sky would look like with a moon roughly 6-8 times brighter than ours.",
"If we assume the mass and orbit of the moon is the same, the effects on nature would mostly involve the amount of... | [
"wikipeadia",
" says the moon is albedo of 0.12 is the reflected light so abolutely diffuse that it would litterally be the difference between a full moon with overcast and a brighter full moon? would there (mabey theoretically) be a focusing point, where there would be something like an actual reflection, and no... |
[
"Question about electricity."
] | [
false
] | Why is electricity so volatile and dangerous? EDIT: What about it causing fires and explosions? | [
"Wow. great answer. I was just clicking through videos on youtube, and on some occasions I noticed that the fire and resulting explosion was orange with black smoke..."
] | [
"Wow. great answer. I was just clicking through videos on youtube, and on some occasions I noticed that the fire and resulting explosion was orange with black smoke..."
] | [
"Duh... makes sense. How about the electrical arc that sometimes happens for a few seconds after opening a circuit? (I hope that the right term)"
] |
[
"Can anyone explain the chemical difference between \"runny\" and \"set\" honey?"
] | [
false
] | I visited myparents house recently and they only had "set" honey, microwaving it for a few seconds made it runny enough to spread easily, but can anyone explain the difference between the two states of honey from a scientific perspective? | [
"Over time, honey tends to crystallize. This is because honey at room temperature is a supersaturated solution, so glucose will precipitate out of the unstable solution.",
"Rock candy is prepared similarly, by making a supersaturated sugar solution. Carbonated water and soda are more examples of supersaturated ... | [
"Honey is ~80% sugars, mostly a blend of fructose and glucose. Runny honey generally has a higher level of fructose. In set honey, the sugars have crystallized and heating them causes some dissolving into the ~15% water content."
] | [
"Fine, added ellipsis to keep my quote fair.",
"It's beside the point though, which is that just because honey isn't crystallized doesn't imply that it has more fructose."
] |
[
"Why the exact moment I turn on my desk lamp (that has lost the protection glass) in a room my speakers, in another room, make a sudden noise?"
] | [
false
] | When I kept them close I figured not having the little protection glass my lamp would "disturb" my speakers (even though I couldn't give a proper scientific explanation), but I was surprised when the same thing happened even when I moved the lamp to another room. When I turn the lamp on I can hear in the exact same mom... | [
"You sound like an early investigator of electricity.",
"When searching for a relationship between electricity and magnetism, someone (Faraday or Ampere or Volta, one of those dudes) tried placing a needle next to a current-carrying wire. Nothing happened.",
"However, when he watched the setup carefully, ",
"... | [
"sounds like you have a bad ground wire"
] | [
"This sounds right to me, I supposed a way to test this would be to find a plug that is not connected to the same breaker. That way they're completely isolated and you can run a quick experiment to test this."
] |
[
"What happens when a muscle cramps, and what happens if it cramps for too long? Does the muscle get damaged?"
] | [
false
] | [deleted] | [
"C is for cookie, that’s good enough for me.",
"But also compression, which is not as fun as cookie."
] | [
"A muscle cramp is caused by dehydration, muscle strain, or overuse of a muscle, among other factors. When it occurs, a sudden and involuntary contraction of the affected muscle takes place. To answer your main question, most muscle cramps are harmless, and last between 30 seconds to 15 minutes. A muscle cramp will... | [
"What does C stand for?"
] |
[
"How much did the invention of the nuclear bomb affect Carbon 14 dating?"
] | [
false
] | null | [
"Oooooh. So much. Eventually anyway. (Also, be sure to see the below comments, people have some interesting corrections/nuance below).",
"The bomb spike began along with large-scale atmospheric nuclear testing. In earnest, this means it peaks ~mid 1960s, (below I've not NOAA's link.) ",
"In short, as one might ... | [
"14C from nuclear testing doesn't have any effect on objects that predate the tests. Carbon is only added to wood or other organic material when it is living. Once something dies, it absorbs no more carbon.",
"The bigger issue for 14C dating used to be atmospheric variation - the amount of carbon 14 in the atmo... | [
"Okay, so what I'm hearing is you can be absolutely confident something came before or after the 60s, but did it interfere with being able to identify how old something pre-1960s something is? Are we still able to be certain that objects like prehistoric tools are actually 10,000 years old?",
"If not, it sounds l... |
[
"Why are all the planets in our solar system orbiting the same “height”?"
] | [
false
] | null | [
"It is unclear exactly what you are asking here, since the planets don't all orbit at the same distance from the Sun (a literal definition of \"height\"). Are you asking why they are all on roughly the same plane? If so, that is answered in the FAQ. If something else, you will need to rephrase your question to clar... | [
"Yes, that’s what I was asking thank you"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"You question is either commonly occurring or has been recently posted on ",
"/r/AskScience",
". It may also be answerable using a Google or Wikipedia search.",
"To check for previous similar posts... |
[
"'Geo' Do seismic shockwaves and vibrations heat up the ground?"
] | [
false
] | I had a dream last night where an earthquake happened and the ground all around me started steaming with heat. I wonder if a similar thing can/does happen in reality? Can the ground feel warmer after a severe earthquake (at the surface)? | [
"Seismic waves heat up the rock they travel through. This is called attenuation. As the waves travel, some of their energy is absorbed into the rock as heat. If this didn't happen, the Earth would never stop ringing after an earthquake. However, the additional heat from the passage of seismic waves is miniscule... | [
"It shouldn't, no. It would just require too much movement to create such a temperature change."
] | [
"yes it does heat up because work is being done. no it isn't very noticeable because rocks are poor conductors"
] |
[
"Earth Sciences How much does the carbonated beverage industry contribute to greenhouse gas effects?"
] | [
false
] | null | [
"Are you asking about the co2 released from when you (and everyone else) open up your cans and bottles of carbonated drinks? ",
"Because that contribution to greenhouse gases is 0%. They get the CO2 as a waste product from fossil fuel burning energy suppliers. So all that CO2 would be going into the atmosphere a... | [
"When it comes to fermentation, the chemical reaction by itself is carbon neutral. The CO2 comes from the sugars which are made by from CO2 from Photosynthesis. Now as for all the processes to do that on an industrial scale, that's another story."
] | [
"I am definitely asking about the CO2 from the fermentation process (brewed beverages) and added CO2 for soft drinks. It would blow my mind to find a source that a majority of beverage companies use waste CO2."
] |
[
"Why does the Osprey use propellors instead of jets?"
] | [
false
] | null | [
"They do use jets. It's a turboprop powered aircraft - jet engines are driving the propellers.",
"They use (very large) props because it's much easier and more stable to hang a heavy transport aircraft's mass from below a rotor/prop disc than it is to balance it on top of jet blast.",
"It's also much more energ... | [
"Awesome thanks, that makes great sense"
] | [
"Since you've already been thoroughly answered I'm going to hazard a pointless little anecdote. I live in Amarillo, and they manufacture the Osprey just east of town on Tiltrotor Drive. Between the wind turbines cropping up all over the panhandle and the regular sightings of Osprey overhead it really feels like I... |
[
"How strong are GPS signals? What would happen if I \"stood\" in front a functioning GPS satellite in orbit?"
] | [
false
] | null | [
"They are about ",
"25",
" to ",
"50",
" Watts depending on the satellite, equivalent to a old style domestic light bulb. They broadcast at 1.6 and 1.2 GHz which is in the ",
"/microwave range.",
"\"What would happen if I \"stood\" in front a functioning GPS satellite in orbit? \"",
"Let's disregard t... | [
"Yes, L-band would never be considered \"far infrared\". The post is otherwise accurate though.\nSource: GPS engineer"
] | [
"Yes, L-band would never be considered \"far infrared\". The post is otherwise accurate though.\nSource: GPS engineer"
] |
[
"[Physics] If matter can't move faster than light, how did the inflationary epoch of the big bang make the universe much bigger than one lightsecond in radius in one second?"
] | [
false
] | null | [
"Matter can't move through the coordinates of spacetime with a velocity of c, but that speed limit does not apply to the changing geometry of spacetime itself. Inflation is not the spreading of matter through space, rather it's the early expansion of spacetime itself. "
] | [
"Up to one doubling per planck time in the extreme limit, but no faster,",
"I haven't heard this before. Have you got a source?"
] | [
"Up to one doubling per planck time in the extreme limit, but no faster,",
"I haven't heard this before. Have you got a source?"
] |
[
"What direction/navigational system is used in space? Obviously things like up and down, or east and west don't really apply."
] | [
false
] | How does one navigate around space? You can't really use the Earth as a point of reference unless you're orbiting it, so how does a probe report back on where it is? Is it in reference to the sun? If so, is the sun actually stationary? Is there some 3D version of latitude and longitude? How are any space navigation... | [
"There are several navigation systems used in spacecraft. Besides ground tracking, inertial and star tracking are particular favorites. With 6 degree of freedom accelerometers and knowledge of a spacecraft's initial position and velocity, location can be determined. These systems have a tendency to drift over time.... | [
"A spaceship in the future might use pulsars to map the galaxy and orientate itself.",
"http://en.wikipedia.org/wiki/Pulsar#Applications",
"Pulsar maps have been included on the two Pioneer Plaques as well as the Voyager Golden Record. They show the position of the Sun, relative to 14 pulsars, which are identif... | [
"Six axis from a known point. If you can't define a known point, you can't navigate, period (you can't figure out where you are going unless you are able to determine a guide for your direction). The earth, with proper mathematics, can be defined in the larger framework of the solar system, our galaxy, and even th... |
[
"How can nuclear reactors work without steam?"
] | [
false
] | There are spacecraft in space right now that are powered by onboard nuclear reactors. Surely they don't use steam to spin a turbine like a normal land-based nuclear power plant. That's a lot of extra weight to carry into space. Turbines are heavy. So how do these reactors work? Have we found a way to convert heat into ... | [
"Well there are no spacecraft in space ",
" that is powered by a nuclear reactor. All the nuclear powered spacecraft operational now are powered by RTGs (radioisotope thermoelectric generator). Other can explain the difference better but the basic idea is that a RTG is a purely passive device that produce heat fr... | [
"SNAP-10A",
" and Soviet TOPAZ were the only spaceborne nuclear reactors. The American version used the thermoelectric effect as ",
"/u/electric_ionland",
" described. The Soviet version used the thermionic effect, which is basically getting something hot enough that electrons start boiling off your anode and... | [
"A well-deserved upvote. ",
"So we ",
" able to convert heat directly into electricity, but it's just really inefficient?"
] |
[
"How feasible is the 'Aclubierre drive'?"
] | [
false
] | null | [
"It isn't. Almost completely impossible. General Relativity is a set of equations on the one side, the arrangement of energy and mass, on the other side, the curvature of space. To do physics, we usually start on the energy and mass side, put in some known energy configuration, like a spherically symmetric mass, an... | [
"I see, I had not thought of the maths being that way. Thank you for explaining it to me. From what I can gather from your post it seems to me that you are saying that general relativity essentially dictates the possibility/impossibility of the Alcubierre drive. Would you mind clarifying what you mean by 'energy co... | [
"ah, well just a few points to clarify, general relativity, the notion that energy and space-time curvature are related ",
" allow alcubierre. The rest of reality is what prevents it ;-). The details are the ",
"Einstein Field Equation",
". The energy configuration, in this case, is the \"",
"Stress-energy ... |
[
"Cross post from r/environment - Which is worse on the environment - Aluminum cans or glass bottles?"
] | [
false
] | From what I understand, there are two major drawbacks of each - with aluminum, you have bauxite strip mining which destroys large swaths of land. With glass production, you have large amounts of energy being used to produce the bottles. There are other issues such as the weight of a glass bottle, the energy needed to r... | [
"You seem to be asking about embodied energy - the amount of energy, logically enough, embodied in that physical product - or how much process energy went in to transport, fabrication, recycling, etc over the entire lifecycle of the product. It turns out that:",
"The energy cost of aluminum is highly dependent u... | [
"While glass certainly requires energy to produce, it pales in comparison to the energy required to produce aluminum.",
"Additionally, glass has actually begun to be re-purposed as landfill cover, after being crushed, because of the extremely low environmental impact it has in a landfill environment.",
"The rub... | [
"The problem with aluminum is separating it from the ore in initial refinement. Ancillary issues with storage of the sulfuric acid and separation byproducts cause immense problems - see the flood in Hungary for example.",
"Aluminum can be reused indefinitely, once it's out of the ground and refined. The problem i... |
[
"Has the power of telescopes increased at a predictable rate? If so, when will it be likely to get a good image of a planet in another solar system?"
] | [
false
] | By "power" I mean the detail that can be resolved. By "good image" I mean being able to see whether it has clouds. Just curious... | [
"Not exactly; telescopes (and any optical device, in fact) faces a fundamental limitation of physics that equates eye/lens size with maximum resolution. Bear with me, my memory on this is a few years old. Basically one way to quantify it is by imagining you're looking at a car's headlights in the distance- at some ... | [
"Good question. It's not so predictable but like many things in nature it can be roughly parametrised by a power law. Now this power law may not hold for long periods of time, engineering limits may be reached but let's put that to the side.",
"To image a planet at say 5000km resolution at 5 parsecs (at 600nm) yo... | [
"3D doesn't come from the width of our eyes, but their distance apart from each other (allowing us to see something from two different angles) ",
"As for telescopes on opposite sides of the earth, we've done that with opposite sides of earth's orbit, 6 months apart"
] |
[
"Quantum computing explanation... non-layman but non-expert version"
] | [
false
] | null | [
"An amplitude is never complex valued."
] | [
"Scott Aaronson: ",
"Quantum Computing and the Limits of the Efficiently Computable - 2011 Buhl Lecture ",
". It's a very interesting lecture but intented non-layman but non-quantum-computation-expert."
] | [
"Well, you've taken quantum mechanics right? So I assume you're familiar with basic QM concepts.",
"To understand QC it's best to not think of any particular realization but to think of an abstract quantum computer. Consider a ",
" probabilistic computer. It is a computer where the input is not a single well-de... |
[
"Is there such a thing is DNA reprogramming?"
] | [
false
] | A couple of people I know have posted this on facebook- To me it seems like nonsense, particularly as the writers seem to make huge jumps between apparent 'findings' and the conclusions they make.Can anyone explain if this kind of thing is actually possible? Edit: Oops, sorry about the typo in the title | [
"Nonsense?",
"I think you are showing a great deal of restraint to describe ",
" as nonsense.",
"I'm trying to describe just how insane that article is but words are failing me."
] | [
"Oh wow. It's complete nonsense. Let's see:",
"Only 10% of our DNA is being used for building proteins. It is this subset of DNA that is of interest to western researchers and is being examined and categorized. The other 90% are considered “junk DNA.”",
"That view went out of fashion years ago. It's well unders... | [
"It's one of those pages that is basically impossible to even refute because you would have to spend 5 minutes on each sentence to fully explain how wrong it is."
] |
[
"In the event of a nuclear war (with humanity's current arsenal being used) How long would it take for the bioshpere to regenerate? (if it would at all)"
] | [
false
] | I guess I should define regenerate. Let's say, pre-war levels of habitability for humans, and animals. Though knowing chernobyl, animals couldn't give a bother about radition. | [
"One of the things to consider in order to address your question is how ecologies have rebounded from previous mass-extinction events. There is quite a bit of litterature on this topic, and the observed recovery times for biodiversity levels vary considerably form a few million years to about 30. I suggest you use ... | [
"Just to be absolutely clear on the extinction level characteristics of a massive nuclear exchange. The main extinction mechanisms are not the actual explosions themselves, which as you correctly point out are local and of little consequence, or even the radiation, but:",
"1 - the mobilisation of particulate matt... | [
"People way overestimate the power of nuclear weapons and underestimate the vastness of the earth.",
"The current total US nuclear arsenal is about 547 Megatons.",
"The largest nuclear weapon ever tested was the ",
"Tsar Bomba",
", which was about 50 Megatons. This bomb was huge and annihilated everything ... |
[
"What are the theoretical limits to flywheel energy storage?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"A good home for this question is our sister subreddit ",
"/r/AskScienceDiscussion",
". It might be too open-ended or speculative for ",
"/r/askscience",
". ",
"/r/AskScienceDiscussion",
" is... | [
"That is unfortune. May I rephrase the question and post again? Possibly \"What prevents us from spinning flywheels faster and faster to store even more energy?\". To be honest, I assumed my question was already specific enough."
] | [
"That's still an open-ended question. It should go to ",
"/r/AskScienceDiscussion",
"."
] |
[
"If/As the universe is expanding, what is it expanding into?"
] | [
false
] | null | [
"From the ",
"wiki on expansion",
":",
"The metric expansion of space is the increase of distance with time between distant parts of the universe. It is an intrinsic expansion—that is, it is defined by the relative separation of parts of the universe and not by motion \"outward\" into preexisting space. ",
... | [
"Correct. Reading the balloon analogy carefully... it says this:",
"A frequently used analogy is the expansion of the ",
" of an expanding rubber balloon.",
"The analogy only wants you to consider the surface itself, not the area below or above the surface (the analogy doesn't work there) - it is actually why... | [
"Thank you! Wish I could upvote twice...once for the explanation and once for referencing Dr. Who."
] |
[
"Why did the solar powered Christmas lights on the tree outside my house light up on the day of the eclipse even though they hadn’t worked in over a year ?"
] | [
false
] | null | [
"We can't really comment on anecdotes / isolated incidents without resorting to speculation which we try to avoid."
] | [
"Okay thank you. Who should I ask to find out more? "
] | [
"You could try ",
"/r/askengineers",
". They have less strict rules for posts"
] |
[
"Is there a temperature where the water vapor in air (causing humidity) turns to ice?"
] | [
false
] | When it drops below freezing, there is still water vapor in the air. Some google-ing explained why this happens, and I am satisfied with this explanation. I'm just curious as to under what conditions may cause water vapor to freeze out of the air. | [
"Here's the phase diagram of water: ",
"http://serc.carleton.edu/images/research_education/equilibria/h2o_phase_diagram_-_color.v2.jpg",
"So if pressure is below 0.006 atmospheres and the temperature drops past the line, it'll re-sublimate."
] | [
"Crossing the red line",
" from bottom-right to top-left is turning water vapour into ice. The temperature needs to be below the triple point temperature (0.01C), and the partial pressure needs to be below the triple point pressure (0.0060373 atm). So if you have water vapour down there, and either reduce the tem... | [
"Others have posted phase diagrams and those are helpful, but I'm not sure that is what you were asking for. Water vapor commonly freezes in the atmosphere, many clouds are composed of ice crystals. The spontaneous nucleation point is ~-42C, a temperature which can be reached in the upper troposphere. More commo... |
[
"If I have two perfectly insulated boilers, one tall and thin and the other short and wide, and I apply the same power to both, does the rate of vaporisation differ?"
] | [
false
] | I'm a home distiller, and I often hear that you will get more boil-off if there is greater surface area of the liquid in the boiler. This sounds weird. Assuming that the boilers are perfectly insulated, have equal masses of identical fluids inside them, and have equal power applied to them as heat, can the rate of vapo... | [
"Why?"
] | [
"Same amount of heat. Same amount of water. The only variable is the area where heat may dissipate into the atmosphere. If they're insulated all around, you're just heating up the same amount of stuff in a different shape. The shape may influence how much the heat spreads through, but I don't think it is possible t... | [
"I'm assuming that you're talking about basically an insulated copper pot with a resistive heater of some kind on the inside. I don't think this changes the details of of my answer, but I'm going to ask some follow-up questions to make sure I know whats going on.",
"My understanding is that your goal is to mainta... |
[
"Why does the maximum number of electrons per quantum level follow the pattern 2, 8, 18?"
] | [
false
] | Quantum level 1 has a max of 2 electrons. Quantum level 2 has a max of 8 electrons. Quantum level 3 has a max of 18 electrons. The pattern of maximum number of electrons per quantum level is: 2 * (quantum level ^ 2) 2 * (1 ^ 2) = 2 2 * (2 ^ 2) = 8 2 * (3 ^ 2) = 18 This pattern continues for quantum level 4: 2 * (4 ^ 2)... | [
"Yes. Electron states are described by four \"quantum numbers\" n,l,m,s. These are subject to the constraints that s=+1/2, -1/2. m is an integer from -l to l, and l is an integer < n. ",
"So for n=1 you have l=0, m=0, and only the 2 possible s values. For n=2, you have l=0, m=0 plus l=1, m=-1,0,+1, times two, so... | [
"The state of an electron in an atom can be described by four numbers:",
"the principal quantum number, or energy level n",
"the angular quantum number l",
"the magnetic quantum number m",
"the spin s",
"But there are also constraints on these numbers. It turns out that l has to be less than or equal to n... | [
"The electron orbit numbers can arise from a very pure mathematical approach to electron orbits. You might be familiar with the \"wave function,\" commonly represented as capital ",
". ",
" is derived from a ",
"certain partial differential equation",
" (PDE) that has the following assumptions (initially a... |
[
"Are there any moments where a severe allergic reaction or an auto-immune response is benefic to save someones life? From an evolutionary standpoint, what's the use of these reactions?"
] | [
false
] | I mean have you ever heard someone say:" luckily this guy went in an anaphylactic shock otherwise he would be dead!!!". Is there any point to be allergic or is it just the system going crazy? What about lesser allergic reaction, rash, swelling, does it have any purpose does it help in any way to something?? | [
"Extreme immune responses are generally harmful, whether they are allergic, autoimmune, septic, or superantigen based. Since the immune system relies heavily on inflammation to recruit cells to an area, having a rapid or prolonged high-level response means that there will be a deficiency of circulating blood for yo... | [
"I wouldn't go so far as to say that \"the autoimmune response is an overproduction of normal immune defenses against cancer\". There are two problems with this statement. First, autoimmune responses can be caused via a wide variety of mechanisms that may or may not be related to each other. Many of these mechanism... | [
"Yes, not all autoimmune responses are related to cancer-prevention mechanisms - I was mainly thinking of NK and T cells here. ",
"Lupus",
" and ",
"rheumatoid arthritis",
" are heavily B cell mediated. However, these are cases of misregulation of the development of the cells or their activity, not an inten... |
[
"When we have nightmares or stressful dreams, does our brain release the same chemicals (cortisol, norepinephrine, adrenaline, etc.) that it would if the scenarios of these dreams were actually happening in real life?"
] | [
false
] | Do nightmares or stressful dreams have just as much impact on us chemically as actually experiencing the things we're dreaming about? | [
"The acute hormonal changes associated with nightmares are not particularly well studied. There have been some studies looking at changes in autonomic tone, including heart rate and respiration, showing that there are occasionally measurable effects of nightmares. Quoting from ",
"this review",
".",
"Most hea... | [
"The method used is to ask the participants after they awaken from REM sleep whether they were having a nightmare. Some studies have allowed participants to awaken spontaneously, others have induced awakenings with stimuli (e.g., loud noises). There isn't yet any way of knowing what someone is dreaming about just f... | [
"Interesting. Somewhat related: How do they study nightmares, or know that the subject is having one?"
] |
[
"How come if I smack a fly in mid-air (not smashing him against a wall) it seems to be completely ineffective? If I were flying around, and a proportionally larger creature smacked me, I imagine I'd be reduced to liquid."
] | [
false
] | [deleted] | [
"This, combined with some of xaltug's explanation gives the whole picture. The force isn't the concern when it comes the fly going splat. It's the tensile stress (force/area). A fly can withstand much larger accelerations and decelerations than we can because as you increase in size, mass grows in a cubic manner... | [
"This, combined with some of xaltug's explanation gives the whole picture. The force isn't the concern when it comes the fly going splat. It's the tensile stress (force/area). A fly can withstand much larger accelerations and decelerations than we can because as you increase in size, mass grows in a cubic manner... | [
"Sorry to nag, but tensile stress is stress in tension. I believe you're looking for compressive stress."
] |
[
"If Pioneer can accelerate itself back towards the solar system by hitting its own dish with photons emitted from itself, doesn't that contradict the law of conservation of linear momentum?"
] | [
false
] | [deleted] | [
"Here's a different way to think of it: ignore everything that happens until the photos leave the dish and go sailing off into interstellar space (since the forces in the previous steps do cancel), and then think of this as an emission event. Each photon has a tiny bit of momentum which it takes from the probe, slo... | [
"Have you ever tried to hold a firehose under full pressure? It is an amazing amount of energy that tries to force you back, and the analogy is lightly equivalent for Pioneer.",
"Think of a fireengine on a frozen lake, it has a full tank of water and starts to spray that water in one direction at high pressure. T... | [
"The trick is isolating the system. You have a certain amount of mass (photons) being expelled from one side, so therefore conservation of linear momentum tells us the system will be accelerated in the other direction."
] |
[
"Why are silicon and oxygen so abundant on Earth? Are they more likely to be formed by dying stars?"
] | [
false
] | null | [
"Oxygen and silicon are abundant everywhere because they can be formed by the normal process of nuclear fusion in a star. Elements significantly heavier than iron are much more rare as they are not produced in normal fusion, but probably in supernovae.",
"A chart of the relative abundance of chemical elements in ... | [
"Iron and lighter elements -- including silicon and oxygen -- are primarily made in stars doing their regular business. Things heavier than iron are mostly made in supernovae.",
"See ",
"http://en.wikipedia.org/wiki/Stellar_nucleosynthesis",
" and ",
"http://en.wikipedia.org/wiki/Supernova_nucleosynthesis"... | [
"Cool chart. I was under the impression that as elements get heavier they were less abundant -- this logically makes sense. But how about things like Li, Be, B,and F? I know Li and F are exceptionally reactive, does this translate into them having less relative abundance, or is some other mechanism at work?"
] |
[
"Can a particle have negative mass or exert repulsive gravity?"
] | [
false
] | I was watching the awesome PHD Comics video, and they mentioned that particles cannot have negative mass, or exert repulsive gravity on other particles. Is it is a a necessary consequence of the laws of physics (as we undertsand them) that a particle with negative mass cannot exist, or is it simply something that hasn'... | [
"I'll only comment on the experimental side because theorists can come up with almost anything.",
"No such particles have ever been seen. However, it has not yet been experimentally verified that antimatter attracts regular matter gravitationally. This has been hard to do because most antimatter we create is co... | [
"I'm pretty sure this is not true. It is true that we think that dark energy is causing the expansion of the universe, but it is not a repulsive gravity effect. It is a pressure effect."
] | [
"This is not necessarily true; again the mechanism of dark energy is completely unknown, but it has been suggested that is a type of repulsive gravity:",
"http://news.nationalgeographic.com/news/2012/02/120215-dark-energy-antimatter-physics-alternate-space-science/"
] |
[
"Since time moves relatively slower where gravity is stronger, if you have two twins the work in the same sky scraper their whole life, would the one who works on the bottom floor age slower than the one who works on the top floor?"
] | [
false
] | I know the difference if any would be minute, but what if it was a planet with an even stronger gravitational pull, say Jupiter? | [
"Yes, by a very small amount. This was shown by raising an atomic clock by a foot relative to another nearby atomic clock, and seeing that it ticked slightly faster. I saw the lead scientist give a talk and he mentioned jokingly that he was kind of sad that after all this development of the most accurate clocks pos... | [
"GPS satellites experience exactly what's being referred to here in a way that must be quantified. Time dilation due to increased speed causes their clocks to fall behind 7 microseconds per day compared to earthbound clocks. The lessened gravity causes their clocks to outpace clocks on the ground by 45 microseconds... | [
"So would these effects always cancel each other out or would there be a point where one force is greater than the other?"
] |
[
"If you have a 64bit processor but only 4 GB of RAM, could you theoretically have the CPU just split the bus width in two and have it use the two sets of 32 bits at the same time to operate twice as fast?"
] | [
false
] | null | [
"It might theoretically be possible, but I don't believe it would give the speedup that you think it would.",
"Let's say that we have a 64 bit bus that is capable of fetching N bytes of data in M units of time. Now compare that with two 32 bit buses, each of which can fetch N/2 bytes of data in M units of time. ... | [
"No, RAM is built to fetch one data line at a time, so being able to address more than 2",
" locations is not at all beneficial for memory accesses.",
"If you are talking about speeding up operations by adding 2 pairs of 32 bit numbers together instead of one pair of 64 bit numbers (assuming your processor supp... | [
"The example you give of adding two pairs of 32-bit integers is actually part of ",
"MMX",
", the earliest SIMD instruction set for x86 CPUs (introduced in 1997)."
] |
[
"How much toilet water is lost due to evaporation"
] | [
false
] | So weird question, Water evaporates and toilets are designed to keep the water level at a certain point within the bowl. I would have to believe then that as the water evaporates the toilet levels the water. So I'm curious our house has no A/C with a small guest bathroom we hardly ever use so how much water would be... | [
"Well, it depends on a lot of different factors; Air currents, humidity, temperature, exposure to light, what kind of toilet it is, and how high the water level is.",
"The easiest way to do it, is probably to measure it practically by taking the toilet apart, removing the supply of water (Turning off the pipe), a... | [
"toilets are designed to keep the water level at a certain point ",
"From my experience, all toilets use the U-trap design to keep water in the bowl. ",
"http://en.wikipedia.org/wiki/Trap_(plumbing)",
"Every time you flush, the U-trap retains a portion of water in the bowl. If you do not use the toilet for a ... | [
"Also might be appropriate for ",
"/r/estimation"
] |
[
"How does a telescope in orbit perform a ten day exposure and not end up with a blurry image?"
] | [
false
] | When the hubble telescope took its deep field exposures it collected light for ten-eleven days. If the telescope is orbiting earth and the stars are also moving around each other and away from us, how do we end up with a clean exposure? Is it because the intensity of the light is so low? After the fact image processing... | [
"No, it is because the things it is imaging are so far away.",
"The angular resolution of Hubble is 1/10 of an arcsecond or 1/2,000,000 or a radian.",
" Even if it moves to the other side of the Sun, that's about 1000 light-seconds away. Nothing farther than 2,000,000,000 light-seconds or about 60 light-years... | [
"Right but Hubble orbited at an elevation of 560km with a 96 minute period. So over a ten day period the satellite rotates around the earth 145 times and its end position in space is 25 million km from its start position due to the movement of earth around the sun.",
"So it seems to me that the telescope would ha... | [
"Right but Hubble orbited at an elevation of 560km with a 96 minute period. So over a ten day period the satellite rotates around the earth 145 times and its end position in space is 25 million km from its start position due to the movement of earth around the sun.",
"So it seems to me that the telescope would ha... |
[
"So if you got shot and weren’t hit in any vital organs (heart, lungs, arteries etc), do you just need to stop the bleeding to survive?"
] | [
false
] | [deleted] | [
"Well, if by \"just stopping the bleeding\" you include surgery required to stop possible internal bleeding, I guess. Gut wounds are almost always a life-threatening situation—you really don't want to introduce the contents of your intestines to your insides. It can be a slow and agonizing way to go. If the bullet ... | [
"Typically it is advised to limit the use of a tourniquet to a maximum of two hours to avoid compications; probably longer if the trauma is severe enough that it is clear that the limb or extremity could not be saved anyway.",
"Your body tolerates your gut bacteria well, and indeed depends on them, as long as the... | [
"why is it dangerous to get shot in the intestines? What's the main souce of danger from that?",
"Infection. Your intestines are full of bacteria. ",
"The membranes of your intestines are a good barrier against the bacteria that live inside, and also have specialized immune cells to keep them under control. But... |
[
"How does the International Space Station get continuous supply of oxygen for the crew?"
] | [
false
] | Do they get oxygen cylinders from earth continuously? | [
"Former ISS flight controller here:",
"The ISS has at least 4 pieces of hardware capable of generating Oxygen via electrolysis (3 Elektron assemblies in the Russian side, and 1 Oxygen Generating Assembly in the US side). As other people have mentioned, there are also Oxygen candles that can be used in emergencies... | [
"According to ",
"this",
" article from NASA they strip the oxygen from water using electrolysis. along with standard tanks of just O",
" (fixed thanks to evilhom3r) "
] | [
"Like this: ",
"*_subscript_*",
"So: ",
"O*_2_*",
"Turns into: O",
"Note that this is ",
"custom CSS",
" in ",
"/r/askscience",
", and will not work on all of reddit (so if you're looking at this comment in your inbox, you won't see it)."
] |
[
"I'm pregnant- if I moved at a significant speed (hypothetically, I'm a jet fighter pilot) are the g-forces exerted on my fetus the same as on me?"
] | [
false
] | On one hand, my instant answer is that they would be, since we share a body space- but on the other, my baby is in a fluid-filled sac. Is there significant cushioning that happens that change the way the forces are exerted on baby? Not to worry, I'm not going up in any F-15s anytime soon, I was just mulling as I drove ... | [
"Your fetus would be protected from some shocks, depending on the density of the amniotic fluid and the flexibility of your belly. But there wouldn't be any protection from a ",
"9g turn",
", for example. In that case, your fetus would be smashed down against your lower spine and pelvis."
] | [
"Not if it's neutrally buoyant.",
"If the fetus is denser than the amniotic fluid, then as you pull Gs, the fetus would sink.",
"If the fetus is less dense than the amniotic fluid, then as you pull Ga, the fetus would float to the top (although the amniotic sac as a whole would smash down onto your pelvis... th... | [
"Fascinating! Once it hits the extremity of the body cavity- it stil isn't undergoing the same amount of pressure? I'm having a difficult time visualizing. ",
"And if that's the case- in the case of a typical, nonpregnant, pilot, why do your organs not get crushed the same way a uterus+fetus would? Or do they? Is... |
[
"If there were oceans of liquid water on the Moon, would there also be tides on the Moon?"
] | [
false
] | null | [
"The moon ",
"wobbles",
"Not a lot, but might be enough for some small variation."
] | [
"but the water table (assuming uniform water spread across the moon) would be higher on the side that is facing earth than the side that isn't.",
"No. ",
"See this picture",
" - ",
" The water table is higher than average in both locations. It's lower on the \"belt\" that neither faces to or away from the ... | [
"The same face of the moon is always facing the earth. This is because the moon's revolution around the earth and the rotation on it's axis is \"coupled\" in that they are going at relatively the same speed. Because the earth would always be facing one side of the moon, you would not have tides that go in and out, ... |
[
"When an electron emits a photon, what determines the direction it is emitted in space?"
] | [
false
] | null | [
"It's random, according to some probability distribution given by the specific nature of the transition.",
"If you have a macroscopic sample of unpolarized atoms emitting photons, the distribution will appear uniform."
] | [
"It's truly random as far as we can tell."
] | [
"Is it truly random, or do we say it's random because the mechanism for how direction is determined hasn't been discovered yet? "
] |
[
"Will the first Quantum computer disrupt worldwide encryption and security?"
] | [
false
] | [deleted] | [
"TL;DR: ",
"No",
"."
] | [
"It's going to be a long slow process from first proof-of-concept prototypes (which we've seen), to prototypes that work reliably, to prototypes that have an actually useful capacity, to demonstrations of breaking weak crypto as another proof-of-concept, then finally something usable in a lab, then the NSA getting ... | [
"Man... that ending is depressing. Not in the scenario alone, but because it's so plausible."
] |
[
"Why is it that when I put in my correct password into the computer, it logs in almost immediately, but when I put in a wrong password, it takes significantly longer to reject me?"
] | [
false
] | null | [
"It's a deliberate pause that serves two purposes. The first is that it makes it take years for someone to try all possible passwords (called a brute force attack). The second is that if the computer always responded as quickly as possible a sophisticated attacker could measure the slight difference (nanoseconds) i... | [
"It's not. But even in that trivial case:",
"Imagine if you had the computed hash and the reference hash in comp and ref. How do you compare them?\nmemcmp(comp, ref) ?\nIf you do that, memcmp will return faster if the hashes near the beginning and will return slower if the hashes diverge near the end. Now, hop... | [
"Do you have more details on a timing attack? I was under the impression that most places hash your password when you sign up. Then when you try to log in, they check your hashed log-in password attempt against the hashed password they recorded in their database.",
"If a password is wrong, the hash will be differ... |
[
"What would fire look like under a microscope?"
] | [
false
] | I'm in biology using microscopes, and this thought just hit me, so I googled the question and nothing came up. I was wondering if you guys could help me out. | [
"It would look like a floating aerosol of soot and dust, each particulate of which would be bright enough to be glowing. ",
"So you know how when you poke a log that's burning and a bunch of glowing embers are kicked up? Keep magnifying and it would look like that.",
"This is assuming a candle type fire. If you... | [
"While candle fires do contain a little bit of soot, most of the fire is wax turning to gas which then burs and so is not that unlike a natural gas flame. Even with wood fire, most of the flame is consists of hot gases, not hot soot."
] | [
"It would look the same."
] |
[
"What two common objects could I use to accurately represent the Scale of the Earth to the Sun?"
] | [
false
] | Somewhat accurately would be a better way to ask it I suppose. Something like a basketball and a pea. | [
"http://www.synapticsystems.com/sky/solarsys/ssscale.html",
"Earth --> Sun",
"Hole Punch --> Beach Ball"
] | [
"30.5cm radius",
"ftftfyfy"
] | [
"30.5cm radius",
"ftftfyfy"
] |
[
"Why can I hear interference on headphones when someone gets a text message?"
] | [
false
] | Normally this happens, I get interference on my headphones, when my roommate gets a text message. I haven't run any tests but the typical situation is that I we will be in the same room and I will be listening to music on my headphones. If he gets a text I can hear a short distribution in the music. I don't think this ... | [
"There is no health hazard at all.",
"What you are hearing is the effect of GSM timeslicing in the (audible) kilohertz range. In other terms it's a pulsed transmission, and you're hearing the pulses."
] | [
"So I found out that putting ferrite choke cores on the cable leading up to my speakers would eliminate the buzz. Follow up question then, If I put ferrite choke cores on balanced audio cable, would it work? Where would be the best place to put them on?"
] | [
"If I put ferrite choke cores on balanced audio cable, would it work? ",
"Probably",
"Where would be the best place to put them on? ",
"At the non-source end. ie. If you're connecting the output of your CD player to the input of your amplifier, you want the ferrite at the amplifier end."
] |
[
"Why does sensor size and not lens size matter for digital cameras?"
] | [
false
] | Media covering digital cameras and smartphones never stops mentioning sensor size. With the release of Nokia L1020, I've had enough. As a person holding a bachelors degree in physics I cannot understand why. After reading several articles on line and searching for it in this subreddit I can't shake this question: Isn... | [
"Yes, the sensor ",
" does, in fact, matter. A larger sensor has a larger area to collect photons. As you mention above, a better lens could, theoretically, just focus that light down onto a smaller sensor. However, the more you bend light, the more artifacting you get. For example, you get a lot of chromatic abe... | [
"The pixels are ",
" in modern CCD/CMOS sensors that they fill up. Think of them as tiny buckets. If your bucket holds a thousand photons, you've got 1000 different brightness levels you can detect. If it's got room for ten, well, you get the idea. A larger sensor has both a wider dynamic range (a bigger diff... | [
"The material that collects photons does not change the density of photons it can absorb just because you use smaller pixels nor just because you can focus more photons on it. You could put 20 pounds of glass in front of small sensor and get the same number of photons onto each pixel but you're going to bleach out... |
[
"If I was standing on Phobos or Deimos, could I throw a ball fast enough to make it goes into orbit around the moon itself?"
] | [
false
] | Not fast enough that it leaves the gravity of the moon altogether but fast enough that it orbits. | [
"Phobos and Deimos have escape velocities of about 40 km/h and 20 km/h, respectively. The speed required for a circular orbit at surface level is (escape velocity)/sqrt(2), so 28 km/h and 14 km/h. That's well below the typical speed of a pitched baseball.",
"However, both Phobos and Deimos are so small and so clo... | [
"I read this and instantly laughed at the possibly of a far into the future youtube video hit. \"Punk kid knocks space station/satellite out of Phobos orbit with baseball thrown from the surface\""
] | [
"With no atmosphere it might be hard breath on either one."
] |
[
"If we can make up a number for \"√-a\". Why can't we do the same for \"(-a)!\"?"
] | [
false
] | I googled about this and I can't really understand well the results. Could someone please explain this briefly? | [
"There's no reason you couldn't, but the question is whether it would be useful. A major impetus behind the definition of complex numbers is that it gives solutions to otherwise unsolvable polynomial equations (most famously x",
" +1=0), and it turns out to have lots of deep connections to other parts of mathemat... | [
"That's a very good point. ",
"/u/oldhelixman",
" has a very good overview of the gamma function extension, and he also points out that it also doesn't \"work\" for complex numbers with a negative real part.",
"Now someone might ask why we can't just declare that that (-n)! is zero for all n>0, or ssomething ... | [
"Note that using the Gamma function doesn't work for (-n)! when n is an integer, because it has ",
"poles",
" at those points."
] |
[
"are there clocks on Curiosity and/or Voyager so we can measure gravitational time dilation?"
] | [
false
] | if so how much difference is there between time in space and time on Earth? | [
"We don't need to go as far as Curiosity or Voyager for that. The GPS satellites are affected by both special relativity (because they're moving quite fast relative to us) and general relativity (because they're farther away from a massive body than we are). The net result is that a clock on board the satellites wo... | [
"If there is any type of processor on board there is a clock."
] | [
"It's accuracy probably isn't good enough to measure the effects of gravitational time dilation. You'd need atomic clocks for that."
] |
[
"Why can't you vent radioactive steam into a container or pressure vessel?"
] | [
false
] | Why do they vent it directly into the air? It seems plausible to me to vent it into a lead container of some type to prevent the radioactive material from entering the atmosphere. Obviously if this was possible, someone else would have thought of it.. so what am I missing? | [
"I think you're missing the fact that they already have one. It's called the drywell, and when the steam pressure builds up there, steam is forced into the torus or pressure suppression pool, located at the bottom of the reactor. The steam is forced through the water, condensing it and lowering the pressure.",
"B... | [
"They weren't exactly prepared for this situation as is evidenced.",
"It's surely possible, but if they wanted to make the plant safer they would have just retrofitted it's backup power to withstand a 9.0 quake rather than built a steam venting holding tank.",
"It was, remarkably, only rated to withstand a 7.9"... | [
"ok.. After all those things have taken place and the gas is finally set to escape to the atmosphere, why not pipe it into another lead container instead? Is it simply the cost and/or mechanical feasibility and risk that prevents it? Is so much steam vented as to create a situation where you would need thousands ... |
[
"Meters are sufficient to measure distance in one, two, or three dimensions. What unit takes its place for the fourth (spacetime)?"
] | [
false
] | null | [
"Spacetime is just space and time. If you call the first three dimensions the dimensions of space, then the fourth is just time. So any units of time are appropriate to describe the coordinate in this dimension."
] | [
"So, what, like a meter-second? I understand that if you were to use vectors to describe relative displacement, you'd have <x> for 1D, <x,y> for 2D, <x,y,z,t> for 4D. But in 1D-3D the magnitude can be expressed as a constant + unit, eg: \"It's 3 meters away.\" Is there not a single unit for describing similar wi... | [
"So, what, like a meter-second?",
"No, just a second. Or a year, or any other unit of time.",
"If you want all coordinates of spacetime to share the same units, then just multiply the time coordinate by c."
] |
[
"I understand that certain elements are only theoretical or mostly can only exist for a extremely short time before degrading. Are there any elements like this that could be combined into a compound that would make them stable?"
] | [
false
] | Please keep in mind I'm talking about the extreme elements here that are so large that they're not even close to stable. Thanks ! Title edit: an* (sorry, forgot to proofread). | [
"Not really.",
"The instability of these elements is a property of their nuclei, and most possible mechanisms by which nuclei can decay are not dependent on their electronic environment - which is what you change when you incorporate an atom into a molecule.",
"Nuclei which decay by electron capture are an exce... | [
"He didn't mention anything about how heavy the elements are, nor does that statement have anything to do with OP's question."
] | [
"That's a good question. I'm not an expert on radiochemistry so hopefully someone more knowledgeable can give you a specific answer. Some general comments though:",
"The result is going to depend on a number of factors, including the specific decay process (so which nuclides are being converted, and what compound... |
[
"What, in your opinion, is the biggest ethical issue in science?"
] | [
false
] | null | [
"This is something that is absolutely subjective so there are no real answers. This is the sort of question we tend to avoid because it is open ended ",
" ethics come into play. These generally degenerate into a gigantic mess. ",
"However, this would be right at home in ",
"/r/askphilosophy",
" or ",
"/r/... | [
"Sorry about that, I'm new here and thought this was a more general discussion subreddit rather than a Q and A type deal. You're right, although it'd be an ",
" mess!"
] | [
"It's all good. We're Q and A here, which is a bit different than most reddits. Those two reddits I listed are actually pretty active so I think you'd get a good response. I know a lot of panelists frequent those reddits.",
"The main issue is that not just panelists weigh in but ",
" does whether they are quali... |
[
"Do certain languages have higher percentage of people who stutter?"
] | [
false
] | I believe (as layman) that some sounds 'trigger' a stutter. Different languages have different sounds, so maybe there are languages that trigger stuttering more than other languages. And if so, which languages has the most people who stutter? | [
"There's another aspect to this. I came across what I thought was a stutter in Zulu speakers when I visited South Africa. Zulu people, speaking English, would sometimes say the beginning of a word over and over several times before continuing. I assumed it was a stutter, but nearly everyone did it. Then I noticed t... | [
"We don't know for sure. There are some theories that certain languages have lower rates (and there's some epidemiological data showing that it might be different in certain countries) but there's a lack of good data to back these theories up.",
"See here:\n",
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC36872... | [
"I’m kinda curious now. With different languages, you’ll have different diets, possibly different races, different regions on the globe, etc. I wonder if it’s a language thing, or more like a regional (lending itself to a dietary or some other odd detail) or some other odd minute detail. "
] |
[
"Does sitting posture have any affect on learning ability, problem solving, etc?"
] | [
false
] | For example, purely anecdotaly, I think that I tend to learn better when I'm comfortable such as being slightly reclined or slouched. But I think I do things better, such as writing code, in a more upright position. That's probably purely personal preference, but I was wondering if there was any scientific corrilation ... | [
"http://en.wikipedia.org/wiki/Context-dependent_memory#Multiple_learning_context_technique",
"This is the closest I could find. Hope it helps."
] | [
"I've read of a study that discussed how various positions and locations we are in affects our ability to learn and retain information. For example, changing where you normally sit or recline to read and study every once in a while can have a positive effect on learning.",
"Some of it is also personal preference,... | [
"Do you have any relevant links?"
] |
[
"What (if any) are the functions of the appendix?"
] | [
false
] | null | [
"Building on this, there is some evidence to suggest that the appendix still plays a role in gut immunology. If you look at histologic sections of the appendix and compare it to the small bowel (jejunum and ileum) you'll find a high concentration of Peyer's Patches throughout the appendix which are more spaced out... | [
"Building on this, there is some evidence to suggest that the appendix still plays a role in gut immunology. If you look at histologic sections of the appendix and compare it to the small bowel (jejunum and ileum) you'll find a high concentration of Peyer's Patches throughout the appendix which are more spaced out... | [
"The appendix is often thought of as unnecessary, however recent research suggests it can act as a refuge for bacteria to hide out in case there is a wide die off of normal gut bacteria (i.e. due to infection with a pathogenic bacteria that outcompetes the normal gut flora).",
"",
"Ref: Heather F. Smith, Willi... |
[
"Do mild infections yield mild immune 'memory'?"
] | [
false
] | TLDR: Is the probability of re-infection from a virus proportional to the severity of the initial infection? I have heard a lot speculate that viruses evolve to be less severe, but hadn't seen any mechanism posited for that to happen. Thinking about Omicron and the number of people who have already been infected with ... | [
"What's your definition of a mild infection? A vaccine with a weakened or attenuated version of a virus could be characterized as a \"mild infection\" and if it's successful it could lead to life-long immunity. Omicron has more mild symptoms but reproduces inside the body 70 times faster, strictly by the numbers ... | [
"I was thinking about the rhinoviruses and non-SARS coronaviruses that cause common colds. Are there just so many rhino & coronaviruses that do not have cross-serotype antibodies that every cold is our initial exposure?",
"Great point about the weakened/attenuated versions acting as vaccines. Upon further revie... | [
"That 70x number is not definitive and just coming out.",
"\"Dr. Michael Chan Chi-wai and a team of researchers found that the variant replicates much faster in the bronchus, which connects the windpipe to the lungs, 24 hours after infection. Yet it reproduces more than 10 times slower in the actual human lung ti... |
[
"Why aren't we already at maximum entropy?"
] | [
false
] | null | [
"We haven't had enough time since the Big Bang yet. The Big Bang was really low-entropy – like, REALLY low-entropy – so it takes a lot longer than 14 billion years for the heat death to come about.",
"In a sense, it's by chance that we exist now, as the time before the heat death of the universe is in theory a lo... | [
"No one knows. You can make the same sort of anthropic argument and say we couldn't be here if it hadn't been... but if you think that the universe was a one-time event then that's not quite the same argument. "
] | [
"Why was the entropy so low?"
] |
[
"Is there any scientific evidence of the idea that harmful toxins build up in your body, that need to be removed by special diets, fasting, or other forms of cleansing?"
] | [
false
] | null | [
"From NPR",
"From the article: ",
"\"The body has its own amazing detoxification systems: the liver and the kidneys,\" says Ranit Mishori, a faculty member in family medicine at the Georgetown University School of Medicine who has reviewed the medical literature on colon cleanses. \"Unless there's a blockage i... | [
"First define toxin. Whilst there are actual toxins in existence, people talking about fasting and detox are often not being precise and scientific. Not only do they misuse the word 'toxin' they don't have examples of specific toxins or toxic substances that their diet will help remove or any explanation as to the ... | [
"On the other hand, none of the cleanse diets or preps will get them out either."
] |
[
"When did the various celestial bodies in our solar system form?"
] | [
false
] | While looking around I noticed that the given age for our sun is around 4.6 billion years, and for every other planet it's ~4.5bya (with Earth given a few more significant figures). I understand that it's nearly impossible to date other planets (and even our own), but is it actually accepted that most of the planets fo... | [
"The planets took a few million years to form. The gas giants grew the fastest, and the terrestrial planets took a bit longer, but the difference is small compared to the 4600 million year age of the solar system."
] | [
"The only thing that can be said is that it's after the ",
"protoplanetary disk",
" had formed. The estimations come from models and scientifically based guesses. The most probable thing that happened. ",
"We know what the different stages are in the birth of a solar system and a star. The timelapses are diff... | [
"I almost went crazy for the title of this post but then I read your description and calmed down. But honestly you answered your own question there mate. We cant ever truly know something like this unless we invent a time machine. Any \"historical\" sciences are just professional guess work and the farther back the... |
[
"Has a solution been discovered for the curvature of space-time due to the hydrogen atom?"
] | [
false
] | null | [
"Sure, you could create a stress-energy tensor for the hydrogen atom, plug it in to the Einstein field equations, and see what you get, but the question is \"are the Einstein field equations still valid on the quantum scale?\" We don't really know how gravity works on really small length scales."
] | [
"If you want a more technical answer, let me give you.",
"The problem is not really Heisenberg. Well, in a sense it is, but it is derived from a more fundamental fact, which is: Observables are operators. In quantum physics, if I write momentum \"P\", I don't really mean that P is a number, but \"P\" is like a ma... | [
"If you want a more technical answer, let me give you.",
"The problem is not really Heisenberg. Well, in a sense it is, but it is derived from a more fundamental fact, which is: Observables are operators. In quantum physics, if I write momentum \"P\", I don't really mean that P is a number, but \"P\" is like a ma... |
[
"How are electrons \"high energy\"?"
] | [
false
] | I read in this AP bio book that as an electron is passed though a series of increasingly electronegative protein pumps to pump H+ across a membrane. The electron is no longer high energy after doing so. Does this mean that an electrons potential energy is measured by it's association with an electronegative molecule/pa... | [
"Sounds like you’re talking about oxidative phosphorylation. Your instinct is right, A free electron is hard to harness and control. ",
"Big fat analogy: metabolism can be though of as a slinky walking down stairs. Each step down is slightly more energetically favorable for the electron than the last, and so it s... | [
"Yes. First off, energy is always a relative quantity, so you're comparing the energy of compounds with and without the 'extra' electron, i.e their redox potentials. (on an aside here, the electron transport chain does not involve any truly free electrons; they're always bound to some molecule, even during intermed... | [
"Pretty much this. Thinking about the electron itself is maybe a bit confusing to the picture-- the passing of the electron down these various intermediate molecules through the cytochrome system is, essentially, analogous to electricity in a circuit. The body exploits this movement of energy by capturing it in ATP... |
[
"Why some stars in the night sky look like they are changing colours or flashing light rapidly?"
] | [
false
] | I just saw one today in the clear night sky and was wondering. Sorry if it’s a silly question. Thanks! | [
"Small fluctuations in our atmosphere cause the light to refract and can appear as focusing, diffusion, or slight colour changes. Observatories are built as high as possible on mountains to try to reduce the amount of atmosphere they have to look through, and the Hubble gets a very clear view because it is in space... | [
"Because planets are closer, they aren’t just a single “point source” and aren’t as affected by things like atmospheric pressure changes. With a regular telescope, you can see them as circles, whereas the stars will still just be the same pixel!"
] | [
"Does this sketch help",
"?",
"The angular diameter of Mars is of the order of 10 arcseconds or 0.5 m over 10 km, the angular diameter of stars is of the order of 0.001 arcseconds or smaller, 0.05 mm over 10 km."
] |
[
"Is there a study on the average/ most common answers for the original Rorschach test?"
] | [
false
] | [deleted] | [
"It's a constructed (synthetic) test - the interpretion table begins with the most obvious patterns. An overall statistic is hard, because it's an open question without limitation what and how you say your inspection/impressions. That is also why Rorschach Test is critisized as non-normalised (maybe that's not an e... | [
"This is spot on. The question is basically asking for the the interpretation table.",
"I always describe the origins of test when I talk about it. Ink blot interpreting stated as a ",
"parlor game",
" - either for fun or to predict someone's future ",
" tarot cards and palm reading, or maybe both. And Herm... | [
"There are tables of content responses used as one part of the test in order to provide some objective determination of common vs. uncommon responses. They are included in the scoring manuals for the various scoring systems, including the R-PAS, the one most current/updated now in use."
] |
[
"How badly would i be hurt if a single atom of anti-hydrogen was shot onto my finger?"
] | [
false
] | null | [
"You wouldn't notice."
] | [
"Aw man i was hoping for something a little more spectacular. Thanks for the answer!"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"megathread",
"If you disagree with this decision, please send a message to the moderators."
] |
[
"How is a number proved to be irrational?"
] | [
false
] | I was reading the pi day megathread and saw this reply: To phrase it a bit differently, how can you prove a number cannot be expressed as a ratio of two numbers? | [
"Usually you assume that it ",
" be expressed as a ratio of two integers, and then derive some kind of contradiction, proving your assumption false (i.e. it ",
" be expressed thus), although it doesn't have to happen that way. In general, there's no easy way to answer questions like 'how do you prove things' be... | [
"Nobody in mathematics calls it that. \"Proof by contradiction\" is a vastly more common terminology."
] | [
"This video",
" shows a simple proof to why squareroot 2 is irrational."
] |
[
"How would time be dilated for a white hole?"
] | [
false
] | I know that the closer you get to a black hole you are moving slower relative to everything else. but if anti gravity were possible would time be moving too fast for us to actually see matter of reverse gravity. | [
"You're multiplying, not adding. If it's less than one it slows and if it's greater than one it speeds up. If it's negative it would go in reverse. General relativity is time reversible, so it really is both the negative and positive value simultaneously. The metric tells you how fast you go through space and time,... | [
"From what I can gather, it's just extending the metric on a black hole. It sort of exists infinitely before the black hole. If you're outside the black hole, you're also outside the white hole. And I'm pretty sure the time dilation would be the same on the inside. As would the gravity.",
"If you mean a negative ... | [
"Negative mass black holes are sometimes called 'repulsons' because they do actually exhibit repulsive gravity. They show up occasionally in semiclassical approximations of string theory, but they're thought to be unphysical and it's thought that in the full string theory description they get 'resolved' or basicall... |
[
"What technologies actually use our understanding of general or special relativity?"
] | [
false
] | I've got this friend who keep saying that all this new astrophysics research is totally useless, and that Einstein's theories don't actually help anyone. But I know that's not true. Can you guys help me out and give some examples of of technologies that wouldn't be possible without understanding relativity, and how? Th... | [
"That might be the only one that uses the general theory, but the special theory is used in many places.",
"Off the top of my head: Radio communications, police speed radar/laser guns, particle accelerators for medical use, nuclear power, and radiation dosimetry all invoke it.",
"Edit for more: Mössbauer spect... | [
"Basically the only technology that does this is GPS, where the clocks on the satellites have to operate at sliiiightly different frequency than the ones on Earth to account for gravitational time dilation."
] | [
"(note: ",
"/u/iorgfeflkd",
" already gave an example of the usage of GR and SR, I just wanted to expand on the bit of \"why is this useful?\")",
"Ah yes, \"why is this science exactly useful?\" question. I always tell them this story:",
"In 1888, Heinrich Hertz discovered the so called \"radio waves\", aft... |
[
"Can dark matter just be black holes?"
] | [
false
] | Pretty simple concept here. I'd find it hard to believe nobody's brought it up before, but I've not heard it so I'll ask. First things first, my starting concepts (in case those need correcting) The question: why can't it simply be that we just don't realize there are vast amounts of black holes providing all the gravi... | [
"That's an idea that has been considered in the past, yes, but it doesn't fit with other observations. It's still technically possible for a fairly narrow range of black hole masses to make up some part of dark matter, but to make up all of it, it is not a realistic mass distribution that all the primordial black h... | [
"I think it's worth noting that recent micro lensing survey such as the ",
"Subaru HSC",
" still leave an interesting parameter space: ",
"Black holes with ~30 solar masses can still constitute around 70% of dark matter.",
" Interestingly, this is exactly the mass range in which LIGO is detecting black hole... | [
"The figure you linked to shows that there's a completely open window in the 10",
" - 10",
" solar masses range. Why is this this mass window usually ignored in favour of the now mostly closed 10-100 solar mass window? Is it just based on interest in that mass range black holes since LIGO sees black holes in th... |
[
"Why there is a need to convert time domain signals to frequency domain signals?"
] | [
false
] | null | [
"Such conversion from time to frequency domain, done using ",
"Fourier transform",
" has a very wide variety of uses. Here are some of those I am familiar with:",
"A lot of devices, including transistors, amplifiers, detectors, our ears and others respond differently, depending on the frequency. Some frequenc... | [
"You're not actually converting the signal to a different one, you're just transforming it into a different domain to look at it differently. For instance, you can't look at a complex waveform in the time domain and be able to analyze it's frequency content. In order to see how a signal or system behaves in the fre... | [
"Awesome explanation. I also heard a lot about Laplace transform that convert the time domain into s-domain (also known as frequency domain?). ",
"Why is there a need to convert the time domain to s-domain? and what is the difference between the frequency domain obtained by Fourier transform and the frequency dom... |
[
"When certain ethnic groups are stated as having a higher risk for certain medical conditions, is this based purely on genetics or general lifestyle for the specific ethnic population?"
] | [
false
] | For example, when I look up Type-2 diabetes, almost all health related websites state that essentially every "non-white race" is at a higher risk. Is this just based on the general dietary and exercise habits of the population, or would a healthy non-white individual still be at a greater risk than an equally healthy w... | [
"The short answer is that both genetics and lifestyle as well as cultural differences are factors contributing to higher/lower risk. Genetics can significantly contribute to risk or response to treatment, diet/cooking and other cultural elements like smoking and alcohol consumption can also directly contribute. Ind... | [
"Thanks for the response. So I guess my next question would be why would South Asians have the same likelihood as East Asians for a disease if the types of food that they eat, culture, and etc are different. Wouldn't it make more sense for them to be in their own category, similar to people from the middle east, s... | [
"It's a false assumption that the same likelihood of diseases is shared between these regions. Actually, individual (separate) risks for ethic populations and countries are documented when possible, but are not always available. ",
"For example, this study compares cancer risk factors and incidence between Chines... |
[
"What is it called when you are awake, blink, and all of a sudden it is morning?"
] | [
false
] | null | [
"Ohhh! I know what you're talking about. It is similar to the feeling you get when you wake up after really blacking out. Like the 8 hours you just spent asleep transpired in half a second. I have no idea how that happens, but sometimes i wish it would happen more often"
] | [
"No. I mean the instant sleep. Where you don't dream. You LITERALLY blink. "
] | [
"Yes! I know. I wish I could control it."
] |
[
"If we received an alien signal, is it even possible that we could decode it?"
] | [
false
] | null | [
"hmm, you could try ",
"/r/AskScienceDiscussion",
", of course."
] | [
"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."
] | [
"Where would be an appropriate place to submit it?"
] |
[
"FAQ Friday: Why are most people right handed? Ask your questions about \"handedness\" here!"
] | [
false
] | This week on we're discussing how and why people show a preference for using one side of their bodies. While we often refer to this as "handedness", it's technically called . Have you ever wondered why most people are right handed? , or ask your questions here! We remove comments containing anecdotes or asking for expl... | [
"Is there any prevalence of handedness in other creatures? For example, do birds have a dominant talon, or do we see handedness in other apes? I'm not even sure how this would translate to non-bipedal animals, but are there similar phenomenon?"
] | [
"Yes! There has been research to suggest that parrots tend to be ",
"left handed",
". in the study 20 parrots were fed a piece of fruit daily and it was recorded which foot they picked up the piece of food with. \"In captivity, a parrot, if fed on the floor of the cage, will descend from the perch, grasp the bi... | [
"Yes, handedness is present in at least some capacity from birth and some research even suggests its present in utero. ",
"This study",
" (sorry pay wall) showed a strong preference for 15-week fetus to suck on their right hand. ",
"Here is a book that reviews newborn handedness",
". Unfortunately my newbo... |
[
"Is there a size limit for terrestrial planets?"
] | [
false
] | Pretty straightforward question, but I'd like to add a wrinkle. Can such a planet form beyond the frost line? | [
"There is, but we don't exactly know what it is. Above a certain mass (",
"approximately ten earth masses",
") the planet is heavy enough to maintain a thick hydrogen and helium atmosphere, so it is believe the cutoff is around there."
] | [
"Because that would make them by definition gas giants, and not terrestrial."
] | [
"Essentially, it is a guarantee. When the mass is great enough, hydrogen and helium cannot be stripped away in the same way that solid material on Earth cannot be stripped away."
] |
[
"How was cancer treated before modern techniques were invented?"
] | [
false
] | I was reading about Adolphe Sax, who's birthday is honored in today's google doodle, and saw this near the end of his biography on Wikipedia: Sax suffered from lip cancer between 1853 and 1858 but made a full recovery. I was always under the impression that cancer was kind of a death sentence back then. Did they just k... | [
"During the 19th century after the invention of aseptic technique, surgical removal of the tumor was the primary method of treatment and the results varied largely depending on the skill of the surgeon and the nature of the tumor. Some doctors would inject bacteria directly into the tumor but it didn't work very we... | [
"Adding on to ",
"/u/Wave_Existence",
", we've been carving cancerous tissues out of people long before aseptic technique, until quite recently that was the only real method of treatment. ",
"Mr. Sax would likely have had a surgery (or several) until it stopped coming back, as we couldn't identify where exact... | [
"Here's ",
"another",
" a source on the history of cancer, people have indeed been cutting it out for a while, but even the egyptians have ackgnowledged that the disease is not really treatable that way.",
"A ",
"side mention",
" of a considerably more modern (late 19th century) but way less bloody method... |
[
"Why can a complex number be used in Physics?"
] | [
false
] | I'm currently trying to understand how to use complex numbers and with that how to calculate with i. I think I now understand the basic math behind it, but I'm still confused how a number, that in some kind of way doesn't exist, is able to describe something like Oscillation in Physics. Or to better describe my questi... | [
"\"i\" is just as real as pi or e or sqrt(2) or -4 or 7 or 1 or 0 etc. We've invented every single number because the way they combine helps us keep track of patterns we perceive. Math is not of the universe, we originally invented math to try to communicate patterns that we see around us, the more intricate patte... | [
"It's a bad name, but used for historical reasons. Technically, all numbers are imaginary so it's not really any different. Math itself exists just in our thinking, but not in reality."
] | [
"Math is not of the universe, we originally invented math to try to communicate patterns that we see around us, the more intricate patterns we perceive, the more intricate our math needs to be to communicate it well. All numbers are imaginary!",
"/u/functor7",
" I love what you've done on this forum, and you've... |
[
"If PCR tests look for specific DNA sequences, how can they be false positives?"
] | [
false
] | [deleted] | [
"According to ",
"this paper",
" the causes of false positives include:",
"They cite contamination and cut-off issues with the two most common sources of error."
] | [
"As an example of how it can occur, PCR uses an enzyme called polymerase to duplicate the RNA/DNA present. Every time it cycles it doubles the amount, until the machine is capable of detecting it, so the more DNA at the start, the quicker it reaches the detection threshold.",
"To bind to the DNA/RNA polymerase ne... | [
"Tl:dr..pcr data interpretation is..complicated.",
"I've noticed an interesting issue I've been had with a PCR test..maybe 1 reaction out of every 100. Instead of the usual logarithmic increase in fluorescence, I see a small increase that creeps up and above the threshold I've set (essentially resulting in what c... |
[
"My daughter was born completely blind in her right eye due to an under-developed optic nerve. Does anyone that follows the sciences closely know of any information or progress in stem-cell work with the optic nerve?"
] | [
false
] | null | [
"I am very sorry but she will, at best, (re)gain very blurry vision in her right eye because the necessary nerual connections in the brain that interpret the signals coming from the eyes mature in the first few months. If in that time the nerves are not stimulated they degenerate and are effectively useless, togeth... | [
"I have \"lazy eye\" in one eye which, as I understand it, is a result of a poorly developed optic nerve. I'm hazy on the details, but I believe my eye was actually removed from the socket and operated on when I was weeks old. ",
"Early on in life, I was made to wear a patch one day a week over the working eye in... | [
"A company called Advanced Cell Technology Inc. is currently working on clinical trials in the US and Europe for macular degeneration. ",
"Scroll down a few times to check out their bio. ACTC.",
"http://seekingalpha.com/article/620561-hope-springs-eternal-in-biotech"
] |
[
"Calling all Material Scientists!"
] | [
false
] | Sorry if this isn't the right place, but I would love it if you could tell me why you're in the material science field and what you're researching (or have done research in previously). I had always planned to study physics in University, but I'm at a university where I didn't get to do straight physics until my 3rd ye... | [
"Hi! Materials Scientist here. I'm doing steel research now for my PhD, but I used to work with thin films of magnetic oxides, which are slightly more physics-y. The stuff I do now is looking at the effect of nitrogen on steels containing aluminum.",
"I'm hoping to go into consulting/failure analysis \"when I gro... | [
"Polymer chemist. I'm researching stimuli-responsive copolymers. In solution, they undergo some change in physical properties based on some external stimuli like pH, temperature, or ionic strength."
] | [
"I got into materials by a long a circuitous road. After high-school I studied enrolled in an applied physics program at a large university and promptly failed out twice. I then worked as an industrial mechanic while going to technical school to be an aircraft mechanic (a&p). I worked on airplanes for several years... |
[
"Why do we measure decay in half-lives rather than just lives?"
] | [
false
] | null | [
"To explain in simpler terms. I've run into a misconception occasionally that OP might be falling prey to. If a certain material has a half life of 100 years that doesn't mean it'll be fully decayed in 200 years, it means about half will decay in 100 years, then half of that half in another 100, then half of that h... | [
"Basically, each atom has an x% chance of decaying during some given time interval. Let's say that an atom of some radioactive element, let's call it Examplium, has a 10% chance of decaying in any given hour. This means if you start with 100kg block of it, and wait an hour, then you can expect that 10% of it will h... | [
"Basically, each atom has an x% chance of decaying during some given time interval. Let's say that an atom of some radioactive element, let's call it Examplium, has a 10% chance of decaying in any given hour. This means if you start with 100kg block of it, and wait an hour, then you can expect that 10% of it will h... |
[
"Can astronauts knock a spacecraft off course my moving around inside it?"
] | [
false
] | Watched Apollo 13 for the nth time and wondered this. They were coming back from rounding the moon, heading for Earth in a (relatively) straight line. They had to do critical course corrections so as to reenter the atmosphere at the right spot. When they were moving around inside the LM and capsule, they were pushing o... | [
"By changing the distribution of mass about the center of mass of the object they can affect its trajectory. Pushing off would not as the sum of all forces would equal zero. It is like trying to pick yourself up to fly."
] | [
"No. I'm going to confuse you by using the term center of mass again, but the center of mass of the system is still the same and it is still moving with the same velocity. This is defined as momentum.",
"For example say you and I are hugging and flying through space. Our center of mass as a system is right aro... | [
"Ah, I see what you are saying.",
"I was thinking when propulsion is on. Let say your craft is a tube and the center of mass is in the middle and the engine is at the end. If you are near the engine and you push off, you would temporarily swing the engine to point at a different direction. During that time, th... |
[
"What happens if a diamond is hyper-pressurized? What about other precious gems?"
] | [
false
] | null | [
"Diamond is quite resistant to pressure - in fact, diamond surfaces are used in pressure anvils for just that reason. If you Google \"carbon phase diagram\", you can see a plot of what happens at various temperatures and pressures. Diamond is what you get a \"normal\" temperatures as you start cranking up the press... | [
"Diamonds can burn like any other form of carbon, not sure what happens when pressure is applied or no oxygen is available.",
"Diamond has a very high melting point, so high that it has never experimentally been reached. So without oxygen and with heat only, nothing much happens :)"
] | [
"Heat treatment of precious gemstones has been practiced for a long, long time. It's a terrible idea with diamonds, the carbon would react with any available oxygen, literally disappearing into thin air, but garnets, sapphires, and topaz can change color and brilliance after heat treatment. Sometimes the value goes... |
[
"Is there a biological basis for being a \"night owl,\" or am I just horribly indisciplined?"
] | [
false
] | I've always been a night owl like my dad. For some reason, my brain just seems much sharper and alert between 1:30 am and 4 am. Conversely, many others wake up naturally with the sun, and can't keep their eyes open past the early hours of the night. It seems that no matter how many times I try to alter my sleeping habi... | [
"There is a biological basis. Medically, the term is \"night preference.\" A Japanese study showed that a polymorphism of the CLOCK gene is strongly associated with being a night owl. Later studies have seen relationships with ADHD prevalence as well.",
"Source"
] | [
"I did a brief paper on the subject a while ago, I doubt I'll find it, but perhaps I can dig for some of the old references later. To put it simply; having variances in the time at which individuals of a particular group sleep provides a protective advantage. If in your group of 12, let's say, everyone slept from... | [
"The influence of the 3111T/C polymorphism on ME preferences in Caucasian populations remains controversial.",
"/Edit:",
"It has even been ruled out as cause of sleep disturbances for untreated depressed patients",
"3111T/C clock gene polymorphism is not associated with sleep disturbances in untreated depress... |
[
"What exactly triggers a salty taste? Will a solution containing only Na+ or Cl- ions taste salty?"
] | [
false
] | null | [
"On each taste bud, called a papillae, there's a few bundles of cells that actually act as a mediator between your mouth and the gustatory nerves that actually send pulses to your brain. On those taste receptor cells, there's 4 different proteins that can bind to different things.",
"TAS1R1 and TAS1R3 bind toget... | [
"You can't have a solution containing ions of only one charge, there has to be a counter ion to make it electrically neutral. ",
"Neither hydrogen chloride (hydrochloric acid) nor things like sodium hydroxide or other sodium salts taste salty. In (very!) dilute solution HCl tastes acidic/sour, NaOH tastes bitter.... | [
"Interesting source! It definitely suprises me that there would be a receptor that requires the presence of both constituents of NaCl to trigger a response rather than the mixed response caused by simultaneous Na+ and Cl- receptor triggers, since receptors within my knowledge only have a single signal molecule site... |
[
"Why is it that I can stand on a balance ball and look everywhere and be steady, but when I close my eyes, I lose balance quickly?"
] | [
false
] | null | [
"Because vision is important to balance, particularly so on an unsteady surface where constant weight redistribution is necessary. 20% of our optic nerve's output goes to our vestibular system.",
"Some ",
"articles",
" to back this up."
] | [
"Really? The links say something slightly different, ie. that good vision is necessary for calibrating the vestibular system and that people with poor vision often have poor balance with their eyes closed."
] | [
"The relationship between vision and balance is discussed in ",
"this",
" classic, educational, and somewhat hilarious video (the video relates to ",
"Lishman & Lee, 1973",
" )"
] |
[
"Could a combination of different types of particle accelerators make hydrogen?"
] | [
false
] | null | [
"Sure, you could split alpha particles to make protons. But that would not be a good way of doing it."
] | [
"On a planet where there's naturally large amounts of water, you can electrolyze water to make hydrogen and oxygen gas.",
"Particle accelerators are not an efficient way to make macroscopic amounts of material. We only use them to produce relatively small amounts of material, and usually only radioactive material... | [
"It just would be nice if we only used nuclear power where no life exists. I'm sure it could still be useful for terraforming in certain circumstances. Like once the raw materials are on the planet. I am pretty sure you are 100% right the more I think on this. Thank you for taking the time to explain it to me."
] |
[
"At what distance from us does the apparent recession of the galaxies due to the expansion of the universe reach FTL speeds?"
] | [
false
] | I am pretty sure it lies beyond the CMB (≈ 14 billion light years away). | [
"Hubble's constant is 70 km/s/megaparsec. Divide the speed of light by this to get the distance at which the recession is that speed. This is about 14 billion lightyears. "
] | [
"This is about 14 billion lightyears.",
"This looks strangely familiar ... Is this a complete coincidence or is this an obvious consequence of something ?"
] | [
"Is this fair, considering Hubbles constant isn't an actual constant. Wouldn't it actually be a given that the FTL point from our POV would occur somewhere during the insanely fast early expansion of the universe? "
] |
[
"What would happen if you applied a lot of pressure but no heat to a piece of graphite?"
] | [
false
] | null | [
"It should turn into diamond, although you might need a lot of pressure and/or a lot of time. See the temperature/pressure phase diagram for solid carbon referenced in ",
"this page",
" or ",
"this page",
". "
] | [
"History of a material can absolutely have an effect on its structure, although often it's more related to kinetic effects. As an example, at room temperature graphite is slightly more thermodynamically stable than diamond, so why do diamonds exist at room temperature? It's because there is no easy way to change ... | [
"That has more to do with the nature of the covalent bonds in diamond (or ionic/covalent bonds in other ceramics) versus, say, metallic bonding in metals. The ability to deform without breaking requires that atoms be able to slip past one another without destroying the structural integrity of the material, which i... |
[
"What kind of digital memory is used in high radiation areas (e.g., in orbit around Jupiter)? What is the expected lifetime of data integrity of these devices?"
] | [
false
] | Also, besides masked or fused prom, is there any digital memory technology that will last the hundreds or thousands of years that could be used in deep space probes? Can you even buy fused prom anywhere? | [
"http://en.wikipedia.org/wiki/Radiation_hardening"
] | [
"3-5 semi conductors with a larger band gap are becoming more popular. It turns out that AlGaAs for example is quite hard to UV, p, n, and e-. ",
"Also, larger chip formats are better because you are less likely to get a cascade event, or a multiple point failure."
] | [
"http://imgur.com/jvyFg.jpg",
"Specs for radiation hardened Sram from BAESystems. Proms are available as well as fused gate arrays. Check em out ",
"http://www.baesystems.com/ProductsServices/bae_prod_eis_rad_hrd_electrnic.html"
] |
[
"How would a Google Password Ring work?"
] | [
false
] | Regarding , explain password rings to me like I'm a STEM graduate student. Where exact implementation is unknown or multiple implementations exists, simply choose any method that would 'work'. I simply want to understand in my head what happens in the background during the interaction, and why the ring is so robust t... | [
"Have you ever used google authenticator? Perhaps implementation would be similar. "
] | [
"Google Authenticator generates a second (time-sensitive) password for extra confirmation. This is not the same thing. Thanks though."
] | [
"I think he means you would need both a text password and the ring to log in."
] |
[
"Let's say an asteroid the size of a small town is heading toward Earth. Where would be the best place for it to make impact?"
] | [
false
] | null | [
"The best spot would probably be in the center of a large continent. Any impact in the ocean would cause immediate tsunamis worldwide followed by long term sea level changes that would cause major damage to coastlines. ",
"Obviously the least populated area would probably be the most ideal. At first I though some... | [
"I was not referring to the volume of the object entering the ocean as the cause of sea level change. I was considering the massive alterations to coastlines and the destabilization of continental ice sheets by tsunami. Do you see that as a possibility?"
] | [
"no real global issues.",
"Only in terms of the Earth's orbit. There would be some very serious global climate issues from an impact this large."
] |
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