title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Could a nuclear waste repository be used as a large scale RTG (radioisotope thermoelectric generator)?"
] | [
false
] | Seems a shame to let all that toxic material go to waste. | [
"I don't see why not. Honestly I think it's just the fact that it generates such low grade waste heat (low heat generation per cubic foot) that it would be impractical and costly to harness the heat. It would be like getting a AA battery's worth of power from a metric ton of nuclear waste. "
] | [
"Not really. The waste that goes into a long-term repository has already had time to \"cool\" off, i.e. the really super highly active material has all decayed away. That's why it can be put into a waste repository without active cooling like it would have when stored in a spent-fuel pool on site at a reactor.",
... | [
"I'm only an armchair power engineer, but I don't think RTGs scale up very well... They're great for long term low power needs, but you get diminishing returns as they get bigger."
] |
[
"Does standing water help you fight bacteria?"
] | [
false
] | null | [
"If you have it, treat the water with a small quantity of ordinary household bleach, about 1ml per liter. Mix well and let it stand a while; 10 minutes or so. It's not perfect, especially for some of the nastier bugs; boiling or high quality filtration are better options by far. But bleach is better than nothing. "... | [
"Boiling the water isn't an option? "
] | [
"If you have a container that you know is reasonably sterile (perhaps rinsing a container with bleach and then washing it out several times very well with boiled water) you could store the boiled water and it would keep while sealed for a decent amount of time (depending how well it is sealed, how clean the contain... |
[
"How did the discovery of DNA affect the field of taxonomy? Were dozens of species 'wiped out' by discovery of identical genetic profiles?"
] | [
false
] | [deleted] | [
"There was reform to a large number of taxa, yes. For example the giant panda and the red panda are no longer considered to be closely related (giant pandas are bears, red pandas are closer to racoons or weasels). In some cases the genetics and the morphology had very different conclusions - bats, for example, were... | [
"I can only comment on microbiology, but the actual discovery of DNA had little to no effect on taxonomy. It revolutionized the understanding of how traits are passed, how the cells work, etc, but classification needs a way to differentiate between the DNA strands. ",
"But to go further with your line of question... | [
"The bacterial flagella is really interesting to me because it's powered by the words smallest rotary motor. It's actually a modified atp synthase, an enzyme that uses the flow of protons to spin a molecular turbine, and uses that kinetic energy to create ATP. The bacterial flegallum uses the same structure, it cre... |
[
"How Does our Brain Identify the Direction a Sound is coming from?"
] | [
false
] | I've seen this topic touched on here, but not fully answered. I've noticed my 6 month old son being able to track the direction of our voices now (he now knows which shoulder to look over to find mommy entering the room while talking). How does our brain process the vector of the source of sounds? | [
"There are three main ways we can detect the direction of sound: 1) the difference in sound volume between the ears, 2) the difference in timing between ears, and 3) the difference in sound quality between the ears ",
"that comes from your head being in the way",
". This occurs because of the physical separatio... | [
"sound waves don't arrive at both ears simultaneously",
"our brain (the auditory cortex) can use the timing differences to create location information. we do not have a full understanding of this process.",
"also, sound creates pressure waves which the brain also uses to assist and supplement the auditory infor... | [
"Thanks for this fantastic response. I had no idea HRTF existed, much less that our brains use it that much, and the simulation was a trip!"
] |
[
"how much degradation of signal strength occurs in outer space?"
] | [
false
] | My six month old wireless router barely reaches my front porch and yet we are able to communicate with Voyager 1 using technology developed over 30 years ago. Is that because there isn't any physical material between us and the Voyager probes? If there are issues with signal strength, what makes us so confident that ... | [
"Your router's antenna is pretty much non-directional, so signal strength falls off with the square of the distance. That is, the strength at two metres away from the router is a quarter of the strength at one metre away. You'll also suffer from walls in the way and interference from other devices.",
"However, yo... | [
"Well, remember a star or a galaxy is also non-directional and we can see those from mind-bogglingly large distances away with sufficiently powerful telescopes. Distance squared falloff doesn't make detection impossible by any means.",
"Also, note that the signals we're looking for will have much greater distance... | [
"Ah. Thank you, kind sir, for offering some clarity to the mysterious downvotes seemingly from nowhere. Do these clarifications rectify my statement's omissions?",
"Per the Inverse-Square Law:",
"the signal strength from ",
" radiation-emitting ",
" source is ",
" proportional to the square of the distanc... |
[
"Do spiral-galaxies slowly collapse?"
] | [
false
] | On the galaxy-scale, I understand that (for at least spiral-type galaxies) there is a super-massive black hole at the center around which is the highest density of stars and other cosmological bodies. Has it been determined whether, eventually, a galaxy will collapse as a result of the overwhelmingly strong gravitation... | [
"There's no reason to believe that an entire galaxy would collapse or fall into a black hole. Just as the Earth orbits the Sun without falling into it, the arms of the galaxy orbit the galaxy center. These orbits are thought to be stable."
] | [
"I see consistently the generalization that there is \"no friction\" in space, which is why the orbits appear to be completely unchanging, but I guess I find it difficult (perhaps impossible) to believe that there isn't at least a marginally small amount of friction which is slowing down, say, the earth's orbit an ... | [
"And you're then suggesting that this friction would slow the orbits and cause the galaxy to be swallowed by the black hole?",
"There is tidal friction, but I think it could be shown that the angular momentum of the galaxy has far, far too much energy to be converted into tidal friction.",
"Also, I found ",
"... |
[
"Black holes exist, but the theory says we can never see something fall into it.... How do you reconcile both affirmations ?"
] | [
false
] | null | [
"Theory doesn't say that nothing crosses. It says that an observer outside the black hole will never see anything cross the horizon.",
"But the infalling object will see itself crossing the horizon and reaching the singularity in finite proper time."
] | [
"Yes thats what i had understood. The theory says an observer outisde never sees anything cross.\nBut a distant observer present at the time of birth and growth of the black would have seen stars eaten by it, no ?\nI mean, he wouldnt have seen the black hole being born from nothing and grow without eating anything,... | [
"An outside observer can see things move toward the horizon, asymptotically slowing down and redshifting until it's not longer visible. But technically speaking, the infalling object will never reach a radial coordinate below the event horizon from the outside observer's point of view."
] |
[
"What necessities (food, air, fluids, etc..) would silicon based lifeforms need to sustain life?"
] | [
false
] | null | [
"This is pretty good background on it:",
"https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry#Silicon_biochemistry",
"The suggestions there, I think, aren't that it's necessarily impossible to imagine a silicon-based biochemistry, but that it's very difficult to imagine a planet where silicon-based... | [
"Keep in mind that the chances of silicon based life is a few million to a few googol times less likley by chance than carbon based life.",
"If there were silicon based life encountered it could occur naturally on Venus for example, but finding such life would be like winning the lottery due to carbon having far ... | [
"Berry interesting, thank you sir."
] |
[
"What does/could a mismatched Systolic/Diastolic pressure indicate?"
] | [
false
] | I noticed that the two numbers always seem to be given in pairs, and the numbers are typically AROUND a 3:2 relation. What does this mean is happening, and what does deviation from this ratio, say moving from 2:1 -> 1:2, suggest? | [
"If you subtract diastolic pressure from systolic pressure, you get what is called the ",
". So for example, if your BP is 120/80, then your pulse pressure would be 120 - 80 = 40.",
"There are many reasons for a narrowed or widened pulse pressure. For example, many elderly people have calcifications of their ma... | [
", If is ",
" higher than ",
", it suggests that somebody doesn't know how to read blood pressure, or that somehow physics has changed.",
"Systolic pressure is the pressure associated with the contraction of the ventricle, diastolic is associated with the filling (or dilation) of the ventricles. The systolic ... | [
"Thanks, and the article was pretty great. Pulse pressure, who knew."
] |
[
"How does ammonium ion uptake into muscle promote mass gain?"
] | [
false
] | I'm learning about trenbolone and I saw this statement in the Wikipedia article about it, and I can't for the life of me figure out the mechanism of action. | [
"How deep do you want to go into it? It seems to act through Akt/mTorc to increase protein translation. Based on wiki looks like it also acts to increase transcription of androgenic hormone receptors, which could increase muscle sensitivity to circulating androgens."
] | [
"That’s really what I’m interested in. Based on what I could find the only thing I could see is perhaps some signal cascade due to amino acid breakdown or possibly converting glutamate to glutamine for ammonium storage or maybe for anabolism of proteins."
] | [
"From other cell types, it might directly phosphorylate/activate akt to kick the whole protein synthesis machinery into gear"
] |
[
"Can the existence of randomness be proven?"
] | [
false
] | [deleted] | [
"Two big topics you're bringing up are determinism (",
"https://en.wikipedia.org/wiki/Determinism",
" ) and time travel paradoxes (",
"https://en.wikipedia.org/wiki/Temporal_paradox",
" ).",
"It's impossible to experimentally disprove superdeterminism (",
"https://en.wikipedia.org/wiki/Superdeterminism"... | [
"I'm on my phone now, so I'll try my best. The experiments you are talking about are related to the famous Bell inequality. So the arguments go like this:",
"1) we have two entangled electrons. Entangled means that they have a special property that the outcome of measuring for instance the spin is correlated betw... | [
"There are several interpretations of quantum mechanics that give different answers to this question, and we can't prove which is correct. Let's assume you can rewind time and observe what happens but you cannot affect the universe in the past in any way. Here is what three popular interpretations would predict:",
... |
[
"Why don't we out gas pollution to space?"
] | [
false
] | null | [
"We do not have the capacity to do that efficiently. Right now 1kg of cargo sent to low orbit cost about $10,000."
] | [
"With heavier gases, such as CO2 and methane, would we need to get to LEO for it to escape our atmosphere?"
] | [
"No you would need to get much higher, which would be even more expensive. If you had a way to capture such gases it would be way more cost effective to store them somewhere on earth or turn them into something else than sending them to space."
] |
[
"How does sunscreen protect my skin if it’s clear? It blocks UV— so if I were, say an insect that sees in the UV spectrum, would sunblocked skin look extra bright because UV is reflected, or extra dark because UV is absorbed?"
] | [
false
] | null | [
"This",
" is a cool video showing what our skin looks like under UV light recording, and at the end you can see what sunscreen looks like. Basically a black paste to the UV, preventing any from reaching your skin below. To answer your question, it absorbs UV not reflects"
] | [
"Now I want a UV camera just to check if I have properly applied my sunscreen."
] | [
"That’s cool. In the last few seconds, it shows the blonde girl who looks like her tooth is chipped under the UV camera, but looks unchipped in the normal light. I imagine that she had a tooth repaired at one point, and the resin used to fix the tooth absorbs UV. (Some dental resins use UV to cure them)."
] |
[
"Photons a massless particle with momentum?"
] | [
false
] | In not a physicist but it seems that to have momentum you would need mass. Anyone mind explaining this? | [
"The other comments are correct, but to you they probably seem like variations on \"just accept that to have momentum you don't need mass\"; if you're asking the question in the first place your curiosity may not be satiated by such an answer.",
"So let's take a step back and look into why momentum and energy are... | [
"Momentum is a property of any particle which is moving, whether or not it has mass."
] | [
"Just a random passer-by but awesome answer! Thanks for your detail!"
] |
[
"What are the risks of not replacing contact lenses as directed?"
] | [
false
] | null | [
"Risks?: serious infections which can lead to blindness.",
"Medical advice?: Listen to your damn doctor.",
"Do a cost-benefit analysis... save a few dollars on contacts vs. expensive medical bills and pain from eye infections with potential loss of sight. I know several people with this money saving attitude wh... | [
"Just on top of this, there are different types of lenses. Daily change, weekly, monthly etc.... ",
"The difference is the design of the lense and how porous it is. Weekly/Monthly lenses let through much more oxygen to let your eyes 'breath' as opposed to Daily wear lenses which are quite solid. As the lenses ge... | [
"The line is where it is. The FDA and contact manufacturer came up with a \nduration which they certify is safe within acceptable limits. Anyone giving you any other advice, especially someone who isn't a medical professional, could be held legally and financially responsible for any negative outcomes you or anyo... |
[
"What % of power output is used to drive a Gas Turbines own compressor?"
] | [
false
] | For example, on an industrial gas turbine that produces 15MW/20000BHP in mechanical drive configuration (twin shaft). It's producing 15MW of shaft output. So from that we can deduce at 32% efficiency it will require 46.875 of fuel. How much energy is extracted from the expanding gases at the compressor turbines, to dri... | [
"Approximatly 50% (it's a little less).\nSource: Son of Alstom engineer."
] | [
"Here",
" is a Pressure volume diagram for a brayton (gas turbine) cycle. Pressure times volume is energy so integrating one of these lines gives you work. The energy required for to compress the air fuel mixture is the lower line, the energy done on the turbine is the upper line. The energy that can be extracted... | [
"Company I work for bought out Alstom gas turbines in Lincoln. "
] |
[
"Question for upcoming art installation: What part of the visible spectrum does a regular CRT tv emit and can it be gelled/modified to support plant growth in a dark room?"
] | [
false
] | As the title implies, I'd like to take junk televisions and support new growth of a plant in a terrarium with them for a few weeks. The televisions would be in a dark room with old vhs footage of sunrises/nature scenes looping. Is this possible if all or part of the screens were gelled red or blue? does a full-spectrum... | [
"A CRT's spectrum is fairly choppy in the red region. See ",
"here",
".",
"Compare this to the spectrum used by photosynthesis, ",
"here",
".",
"You can see that the blue may be well covered, but not the red. \"Gelling\" or filtering cannot add any frequencies to the spectrum, it can only subtract. A fu... | [
"It doesn't need to be well covered. Most of the red photons will have wavelengths that are well-absorbed."
] | [
"http://en.wikipedia.org/wiki/File:Chlorophyll_ab_spectra2.PNG",
"There's the chlorophyll absorption spectrum. ",
"http://media.wiley.com/product_data/excerpt/24/35273140/3527314024.pdf",
"That has emission spectra for the phosphors used in CRT sets. ",
"Gelling can only reduce the light a plant receives,... |
[
"Does alcohol consumption provide any positive effects?"
] | [
false
] | Are there any short term or long term side effects of alcohol consumption which can be argued as being "good for you"? | [
"Yes. The benefits of moderate alcohol consumption are well studied and documented. ",
"Here",
" is an article on some of the benefits. That said, heavy consumption can damage the body."
] | [
"There are a few, but they're mostly poorly understood and attributeable to parts of the drink other than the alcohol. Red wine has many of the same attributes as red grape juice, for example.",
"The one positive effect I do know though is that it prevents methanol poisoning. Your body can't handle methanol, but ... | [
"Think of alcohol consumption and risks like a Nike swoosh. ",
"For men \n0 drinks and 2 drinks have equal long term Cardiovascular risks and benefits \nHowever those who drink 1 drink per day ( it can be wine, a shot of whisky, a beer, etc) showed a decreased risk than those who drank 0 or 2 drink. ",
"However... |
[
"Is there an upper limit to the highest possible bypass ratio of a turbofan engine?"
] | [
false
] | I am not an engineer and only have an rudimentary understanding of the physics behind the jet engine, especially for commercial airliners. Admittedly, much of the physics behind why a high bypass ratio for commercial airliners is fuel efficiency was quite counter-intuitive for me, I.e slower compressor speed and more ... | [
"Theoretically, no. Practically, there are many limits.",
"One quick example, as a fan becomes larger it would become a propeller. ",
"There are several limits to the overall diameter of both propellers and fans, in no particular order (it will be different for every airplane)\n- the structural integrity of t... | [
"Just latching on to this explanation to add: Another factor limiting the possible bypass ratio is the fan tip speed. The larger the outer diameter, the lower the possible RPM of the fan is before reaching Mach 1 at the tips and encountering problematic compressibility effects. This is currently addressed in (Ultra... | [
"There is actually an example of this, the ",
"propfan",
". Also known as an ultra-high-bypass turbofan engine."
] |
[
"How large would a population need to be to insure that the species could grow without inbreeding?"
] | [
false
] | null | [
"The number, according to geneticists, comes to 160 people- 80 men and 80 women. This of course depends on the variance in genes, so these people would all need to be as distantly related as possible. While some animals are all genetically the same, humans need a pretty big gene pool to not turn out abnormally. ",
... | [
"I have a curious question I'd like to piggy back off of this one with. If all but one woman were to vanish from Earth, leaving her with her choice of male mates, how likely is it that she and her offspring could repopulate the Earth with minimal negative side effects? If it helps the odds, let's say during her e... | [
"How long before a 2 person colony dies off?"
] |
[
"Is it possible for an earth-like planet to have a ring around it?"
] | [
false
] | Or would the ring effect it? | [
"Yes, terrestrial planets can have rings."
] | [
"Yes you do if you state that kind of fact.",
"The common theory about the theory of the moon is the giant impact hypothesis: A big body hit earth and the ejected material formed the moon.",
"But even if earth and moon formed out of the protoplanetary disk this does not imply the existence of a planetary ring u... | [
"Yes, just imagine breaking our moon into pebbles."
] |
[
"Brown Dwarfs?"
] | [
false
] | When a nebular starts to come together, the core of it starts to heat up due to friction. But if it does not have the required temperature to begin nuclear fusion it becomes a brown dwarf. My question is do brown dwarfs glow or let out light energy, and if so where does this energy come from, and will it run out of ene... | [
"More massive brown dwarfs can burn heavier elements than hydrogen, like deuterium or even lithium. Otherwise, most of their radiation comes from residual energy left over from gravitational contraction. Eventually, like an ember, they'll run out of energy, cool down and fade to black. But this process takes longer... | [
"Everything with a temperature above absolute zero gives out radiation. See the Wiki for ",
"black-body radiation",
" for a detailed explanation. But brown dwarfs, as explained in it's ",
"Wiki",
" give out extra radiation, the energy of which comes from gravitational contraction and radioactive decay. Ye... | [
"So, all the stars will \"shut down\" after a while? Will new ones for or when the ones we have are done it's all done? What's the timeframe for this to happen?"
] |
[
"Are callouses made of living tissue?"
] | [
false
] | null | [
"Most of the skin on the outside of your body is made up of many generations of dead skin cells that have flattened and bonded together to make a thick disposable surface.",
"Callouses are just thicker parts of dead skin cells that make up your epidermis."
] | [
"Why don't they go away?",
"They do, if there's no more need for them. Meaning, if you sand them down with a pumis stone, etc., they will just keep coming back thicker and thicker because the body will keep seeing a need for them as the skin keeps getting abraded away.",
"But if you gently rub in lotion at lea... | [
"I just want to add that as a guitarist, my finger tips are always calloused. However, every now and then a fairly thick layer of callous will lossen up and peel off. They definitely remove themselves over time (usually in far less dramatic fashion) but also continue to build up at the same time - if they're caused... |
[
"How much can you learn from someone's genome?"
] | [
false
] | I've heard you can learn id someone by looking at their DNA, but what else can you learn if you know what to look for? | [
"Well this is fun, we literally just covered this kind of stuff in my advanced molecular biology course.",
"Your genome will contain variation depending on genetics that has been passed down from your parents. You may be homozygous for 11 copies of a short-tandem repeat (STR, 2-3 'letters' repeated over and over... | [
"Sorry if I am misunderstanding what you said (I'm not very knowledgeable when it comes to science), but from what I can understand it sounds like you can predict what diseases may have been passed down to me from parents and grandparents, what diseases I might be prone to, and some traits I might have. What kind o... | [
"The relationship between genetic inheritance and environmental effects is one of the hottest topics in research right now.",
"Medicine related Pharmacogenomics looks at how your genes will predict your response to drugs. Understanding these links can help us predict allergies to medicine, how we'll you can meta... |
[
"Why is that that \"flu season\" seems to be in the fall/winter months? Is the virus less communicable throughout the spring and summer?"
] | [
false
] | null | [
"It seems that the influenza virus survives longer in cold, dry temperatures. Dry air creates lighter mucus particles which travel farther in the air. ",
"https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.0030151"
] | [
"Not an epidemiologist, but it's my understanding that it has more to do with human behavior. As the weather changes people spend more time indoors in closer contact with other people allowing the virus to spread."
] | [
"fresh air",
"And I thought that general scientific knowledge is long past the Miasma theory.",
"https://en.wikipedia.org/wiki/Miasma_theory",
"\"Fresh air flow\" have nothing to do with it.",
"There are several factors why flu is in cold months, but not because of congregation.",
"We are protected by muc... |
[
"Why haven't we found any meteorites older than 4.5b years old?"
] | [
false
] | Isn't it possible for meteorites to come from interstellar space? Or even intergalactic space? Why aren't there any meteorites older than our solar system? | [
"It's possible, but the odds quite low. The solar system is generally believed to have ejected between 10 and 100 Earth masses in rocks during it's formation (there's a lot of uncertainty, but it's pretty reliable that something like this happened, since the same process forms the Oort Cloud.)",
"It was mostly i... | [
"Actually, no. Meteorites are mostly the remnants of the molecular cloud that formed our solar system. We can use them to determine the age of the solar system, about 4.6 billion years.",
"Small rocks like those that hit the Earth as meteorites can only form when a molecular cloud, like the one that made up the s... | [
"This is great info, thanks for this. It seems like interest in meteorites is increasing, and the hobby of \"prospecting\" for them for cash as well. I, for one, hope one is found. I think it would be very exciting and the scientific value would be tremendous, I would imagine."
] |
[
"how effective, honestly, are surgical masks in the fight against airborne illnesses."
] | [
false
] | It just seems that there can't really be a breathable material that would trap germs significantly. And even if it did, aren't there already billions of pathogens floating in the air? And a mask really doesn't seem like it would make a notable difference. And I do realize that this is a stupid question, but I couldn't ... | [
"Different masks are rated differently, based on how much particulate matter in the air they let through on inhalation.",
"A typical surgical mask is not designed to protect the wearer from the environment, but the environment from the wearer; it has poor fit around the edges, and its main purpose is to trap exha... | [
"Ok so what about the chinese that are using them for the thick smog. How is that effective? "
] | [
"I work in a hospital and by the time that they usually suspect that a patient may have something which could be airborne, we'll usually have spent quite a bit of time with that patient, breathing the same air as them. Usually the first we know is when we have to start gowning up and the masks appear outside the do... |
[
"Are the mobility of heavy metals (all) always higher under reduced conditions?"
] | [
false
] | null | [
"The solubility of metals depends heavily on what they are complexed with. For example, halide complexes of HMs tend to be highly soluble, whereas oxides tend to be insoluble. In these cases the oxidation state has little correlation with the solubility. These are both examples of metals in positive oxidation state... | [
"You'll need to clarify your question a bit.",
"By mobility do you mean diffusion? And I assume by reduced conditions you're referencing the oxidation state.",
"Smaller, lighter, and hotter materials diffuse faster. The temperature should be referenced with respect to the melting point of the material."
] | [
"Sorry about the confusion, I mean solubility of the material in water, or mobility if you factor in the flow of water."
] |
[
"How do scientists make sure that the light they are getting is from that particular heavenly body and not a nearby star, like the Sun?"
] | [
false
] | Did not know how to word it in google | [
"This question is extremely broad. Your question will most likely be interpreted as:",
"\"How do Astronomers get spectra of specific objects when there are other objects nearby?\" ",
"The answer to that is, we just block out the other light. Here's an example of an SDSS plate that takes a bunch of spectra from ... | [
"I'd like to add that fiber optic cables operate as a sort of filter themselves. ",
"Fiber optic cables work thanks to a phenomenon called \"Total internal reflection\": light cannot travel from a material with a higher index of refraction into another one with a lower index when encountering their interface (sur... | [
"To prevent confusion from overlapping light sources and scattering they analyze pictures from different locations and because the stars are at a different distance they will appear at a slightly different angle. They can then triangulate the image data to see the exact distance. ",
"I've worked as an astronomer ... |
[
"Is gas spent driving uphill offset by going back down?"
] | [
false
] | On my way to work everyday I have to drive up a big hill, and on the way back home I obviously drive back down the hill. If the hill never existed and the distance was flat, would the gas spent be the same? Of course it wouldn't be spot on but is it close? | [
"A lot of the gravitational potential you have at the top is transferred into heat (friction) and sound as you come down the hill, so you won't break even."
] | [
"Well if its a frictionless slope, you and your car are screwed going up and down."
] | [
"If we assume that you are trying to maintain a constant speed, then no, they will not be close. You must spend excess gasoline with respect to your drivetrain's overall effeciency to comensate for the potential energy gain of driving up the hill. Once you peak and start back down, you must use your brake to prev... |
[
"How are nutrition facts on every food item specifically calculated? Are any assumptions made in the process?"
] | [
false
] | null | [
"This always puzzled me. A wooden chair would have a certain amount of calories, but they are not accessible via digestion. Does this phenomenon happen with food? I don't see why it shouldn't."
] | [
"There is stuff in our food that burns and I assume shows up on the calorie count that we can't process (like fiber), so there is a discrepancy."
] | [
"Sure, but if we are interested in nutrition info, we don't care about the calories we can't get and the method of burning in a calorimeter doesn't take it into account."
] |
[
"why do bugs die upside down?"
] | [
false
] | Like roaches, when you kill them, they flip over. Why? | [
"Spiders move by applying hydraulic pressure to extend their legs. When they die the pressure reduces and their legs curl up beneath them. The dead spider is top heavy due to the body being above the legs, and the curled legs form a curved bottom. Such a structure will naturally roll over onto the spider's back. ... | [
"What organ allows a spider to move it's legs so quickly and accurately? And what does it use as it's hydraulic fluid? "
] | [
"Spiders, like us, have a hard skeleton moved by muscles. The difference is that their skeleton is on the outside - that's why it's called an exoskeleton. They also have hydraulic movement, which we don't. So the movement of spiders (and most arthropods) is a combination of both muscle-skeletal interaction, and hyd... |
[
"Why are there no thunderstorms in the winter?"
] | [
false
] | Not really winter for everybody, but I live in a colder area of the country where it is typically below freezing and I don't think I ever remember hearing thunder or seeing lightning in the winter time. Why is this? | [
"Nevermind, did a little research and found the answer!",
"In case you're curious like me:",
"It is a matter of humidity. The cold weather\nthat allows snow means the air is not humid\nenough to allow an electric current to travel\n(along the water vapor in the air) over the differently\ncharged clouds and sky.... | [
"It is entirely possible to have a thunderstorm in the winter. ",
"There's even a Wikipedia article on it."
] | [
"I've been in at least two thundersnows before, in Kansas. Mightta been three, cain't 'member."
] |
[
"If we extracted all excess CO2 from the atmosphere, how large would the pile be?"
] | [
false
] | Assuming we had a way to extract all the carbon emissions causing climate change from the air, how large a pile of carbon would we have? Where would we store it all? | [
"Using what method? Different methods of sequestration exist, leaving different end products and this different volumes. ",
"Let's break out a napkin and run some rough numbers. \nLet's assume we have boundless energy, and could somehow extract the carbon and form it into diamonds of pure carbon.",
"We're start... | [
"19 billion cubic meters is so hard to relate to. 19 cubic kilometers is much easier. Thanks for the work, though. :)"
] | [
"Wow! That's a lot of diamond. Thank you for the response."
] |
[
"Do we know of covid-19 reservoirs in wild animals yet?"
] | [
false
] | Knowing that Denmark had to cull their mink population because they contracted covid-19 and knowing the role of wild bird populations with regards to influenza, what do we know of similar wild animal populations that could play an important role as virus reservoirs for covid-19 in the next couple of years? Thank you ve... | [
"Well, the virus probably originated in bats, so those bat populations probably still harbor the wild-type of the virus and/or its close relatives. ",
"Also this coronavirus is demonstrably capable of jumping between species, so it should not come as a big surprise if the virus spills over from humans into other ... | [
"The virus is most likely a zoonotic disease, and other coronaviruses have been shown to infect various animal populations. Sometimes it's a deadly infection (therefore less likely to function as a reservoir species) and sometimes they aren't as severely affected. My understanding of the mink culling is that they w... | [
"We're way past this point. The reservoirs are humans. Just like we never could eradicate the flu or the common cold. Experts predict it will remain circulating, hopefully less deadly over time. The culling probably had more to do with slow the spread of disease in the short-term."
] |
[
"Why does it take so long for radioactive material to decay?"
] | [
false
] | null | [
"All things being equal, the more energy a decay releases the faster the decay happens. This is because in quantum mechanics the more ways an event can happen the more likely it is to happen quickly, and if there is more energy to distribute among the decay particles then there is more ways to distribute it. Enri... | [
"It doesn't, necessarily. Nuclear decays have half-lives ranging from zeptoseconds to hundreds of billions of years. Some species decay very quickly."
] | [
"Additionally, some decays are strongly suppressed because the vast majority of possible decay channels can be forbidden by other conservation laws, like conservation of angular momentum."
] |
[
"What evidence do we have that suggests the universe is infinite?"
] | [
false
] | I cannot find a concise article or report on Google which describes the whole of our current evidence supporting the now mainstream view that the universe is infinite. Can someone help me out here? | [
"It is believed that we live in a freidmann universe. This is a universe theory that forwards 3 possibilitys: a closed universe, an open universe and a flat universe. A closed universe's shape would be similar to that of a sphere, all space connected. An open universe is shaped like a saddle, and a flat universe is... | [
"Sorry to confuse you with the flat like \"paper\". When we mean a flat universe we mean that the geometry of the universe is such that parallel lines will never cross, the angles in a triangle will always add up to 180 degress, and the corners of cubes will always make right angles. We call this kind of geometry E... | [
"There's no way to know, since we can only see as far as light has traveled. We know the \"observable universe\" to be finite, but again, that is bounded by physics. Any theories regarding an infinite universe are conjecture, because from our point of view the light from some parts of the universe hasn't had enough... |
[
"Can we create mass from energy? Or is it impractical?"
] | [
false
] | I know we're well accomplished at releasing energy from mass - been doing it since Trinity - but does science ever go the other way? Have humans ever created mass from energy? | [
"This is what happens in particle accelerators: particles with a lot of kinetic energy collide and produce particles with mass, at the cost of that kinetic energy."
] | [
"You could say that mass is a ",
" of energy, and the \"classical\" view of mass is just energy bundled together into a bound, stable state (as opposed to, say, kinetic energy). So the question that you're probably asking is, can humans create ",
" (or other stable forms) from raw energy.",
"The physics that ... | [
"Well, there's a certain amount of energy before. There's the mass of the two protons (remember E=mc",
" ), as well as the kinetic energy of the particles. Then they collide, the kinetic energy is reduced, and a bunch of particles shoot out. They all have mass, and that mass as well as their kinetic energy adds u... |
[
"Do animals (humans in particular) have pre-built in beliefs?"
] | [
false
] | null | [
"I see. I wouldn't call these beliefs. I would rephrase the question as \"is there an instinctual fear response to spoders\" for example. ",
"There is some evidence for differential responses to snakes and spiders in 6-month old infants (",
"Hoehl et al. 2017",
". However, whether this is a fear response or n... | [
"What do you mean by beliefs? Can you give an example?",
"Birdsong is not a belief..."
] | [
"For example: Killing people is bad. Spiders are scary.",
"Doesn’t it base itself on beliefs? It is knowledge to say the least and every knowledge is also a belief."
] |
[
"How does the hydraulic ram water pump work and why does it not violate conservation of energy?"
] | [
false
] | [deleted] | [
"In hydrostatics where the water velocity is zero or small pressure will be equal in the whole system and the maximum height of water will be the same in the whole system.",
"Looking at the water ram it takes a moving stream of water and suddenly stops it by closing the waste valve. This sudden stop mean the pre... | [
"Also even if you ignore the kinetic energy component of the description (which is important to its operation) you still should be able to work out a potential energy balance. In this case, you start with a pool of water at a middle elevation and end up with some water at a higher elevation and some water at a much... | [
"This is a great explanation. Dynamics are not necessary to explain the gravitational potential energy before the pumping and after. "
] |
[
"Reading the 'fan theories' thread from a few days ago made me wonder, is there any truth to the idea of heavily traumatized or comatose people inventing alternate realities to \"cope\" with their state?"
] | [
false
] | Many of the theories were based around the idea of someone being traumatized by an initial event, with an extremely intricate and complicated reality invented within the mind of the individual to cope with that trauma. Is there any scientific evidence of the human brain actually inventing extremely intricate realities ... | [
"Well, that is one of the ideas behind ",
"Dissociative Identity Disorder",
" (formerly called multiple personality disorder). Another interesting dissociative disorder (dissociation simply means a split from reality) is dissociative fugue. In this condition, the sufferer will leave their current situation, oft... | [
"Paul Bloom of Yale has posted his introduction to psychology lectures on iTunes and YouTube. They are fascinating. The section on psychopathology covers dissociative fugue if you're interested. It's been a while since I watched them, but I believe he mentioned that there was some doubt as to whether this was a \"r... | [
"Paul Bloom of Yale has posted his introduction to psychology lectures on iTunes and YouTube. They are fascinating. The section on psychopathology covers dissociative fugue if you're interested. It's been a while since I watched them, but I believe he mentioned that there was some doubt as to whether this was a \"r... |
[
"Questions you have or recommend I ask for select MIT Brain and Cognitive Sciences Researchers/Professors?"
] | [
false
] | I wasn't sure if this would be the proper category for this post, but I figured I would get the most feedback from this subreddit of prestigious repute. I will have personal access to the following 6 individuals for the next week thanks to a "Research Topics in Neuroscience" mini-course I'm taking: If anyone has any qu... | [
"For all:",
"Brain imaging system ",
" is becoming more and more refined. How do you imagine future advances affecting your studies? Will you be able to pinpoint more precisely the group of neurons responsible for your specific brain function? (hint: the answer may be difficult as the number of neurons invol... | [
"For your own career planning, you might want to ask them how they got into the field (what drew them, what paths they took getting into it). You'll probably get a lot of stories and it'll help you figure out if it's an area you really want to pursue."
] | [
"I've just got one for all of them. I'm curious as to whether they have any interest in altered states of consciousness (meditation, dissociation, psychedelic experiences), and if they have any ideas about whether or not they can contribute to our understanding of human cognition and intelligence in general. "
] |
[
"Why did our immune systems evolve so that we need our meat cooked? (please read description)"
] | [
false
] | My question, as stated above is, why do we need our meat cooked? I know it is because we need to get rid of the bacteria, but every other carnivore or omnivore does not need their meat cooked. So why does ours? Why would our immune system evolve so that we need meat to be cooked? Why would it need that extra step to be... | [
"We do not need to eat our meat cooked.",
"Does it kill bacteria? Yes. But that is an added benefit.",
"If you were to eat raw meat straight of the bone right after it was killed, as animal carnivores do, you would not need to worry about bacteria. Bacteria only move in and set up shop and multiply after hou... | [
"I never even thought about how they eat their prey directly after they kill it so no bacteria is on it. Also about how it simply an added benefit to make it more easily digestible. Thanks for answering and giving me a very complete and straight forward answer."
] | [
"Not to mention the fact that animals DO get sick if they eat a sick animal. That's one of the many reasons wild animals don't live as long."
] |
[
"How did scientists figure out that coal came from plants?"
] | [
false
] | null | [
"There are lots of grades of coal, and one of the lightest, lignite, is full of plant residues. Cook and squeeze lignite and you get shinier, more homogeneous coals: anthracite. Peat is a clear precursor of lignite and you can see peat forming from plant residues. The huge amount fo coal formed in the Carboniferous... | [
"Sometimes there’s fossil scale trees and stuff in it. So it’s clearly made of plants.",
"That’s not the full answer (because paleontology is my autistic special interest, not my job) but I just wanted to chime in if no one else did"
] | [
"Kind of... there's fossil trees in other rocks too, but those rocks didn't come from plants. And we find animal fossils in coal too (just in case someone is curious: no, coal is not made from dinosaurs either). But like you I'm struggling to find a good explanation of how we know.",
"https://theconversation.com/... |
[
"Would the radioactive spike shown in those trees from ad 774* (let's not get into dates being wrong or right) could that radiation have any significant effect on genetic data?"
] | [
false
] | kind of like a nuclear fallout. If so, how much? | [
"No. You're looking at a small percentage increase in a naturally occurring carbon isotope (about 1 part per trillion of all carbon). You could only detect that difference by very careful analysis be mass spectrometry, using carefully prepared samples. Waving a geiger counter near it is not going to show anything, ... | [
"You are right that the actual C-14 spike would have no measurable impact on life, but whatever generated that spike may have. C-14 is made when radiation impacts the upper atmosphere. If there were some large event that caused C-14 concentrations to spike (like a nearby gamma ray burst), it may have been enough ... | [
"Yes, I guess I took the question a bit literally.",
"Anyway, the most popular explanation (something which has to close enough to inject high altitude radiation but leave no presently visible trace) seems to be solar flare activity, which would be entirely buffered by the atmosphere. Interesting piece ",
"her... |
[
"How come modern computers still use floating point arithmetic instead of having hardware supported rational numbers?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"If you disagree with this decision, please send a ",
"message to the moderators."
] | [
"flawed premises",
"Could you elaborate, please?"
] | [
"There are multiple issues:",
"If you have a more specific question, please clarify it with some relevant bibliography, then feel free to resubmit."
] |
[
"Do NSAIDs reduce healing times?"
] | [
false
] | Just curious here. I recently posted a similar question to and got a wide variety of mutually contradictory answers. Is swelling at an injury site an undesirable response by the body, or is it like a fever where it serves a beneficial purpose? | [
"I'm pretty sure an immunologist will come along (or I'll summon one), but here's my take that I feel is accurate from my studies:",
"Inflammation is caused by your body trying to clean up the mess from an injury. If there's tissue destruction or blood vessel damage, debris from that injury is going to sit around... | [
"NSAIDs are not so effective that they stop the entire inflammatory process, but instead they are another tool that will control it. If the inflammation gets to be too severe, then the swelling itself will cause issues with the healing process and can possibly lead to large amounts of swelling becoming permanent. I... | [
"I agree with your statement 100%. The main issue is there is no conclusive answer to this because there are too many studies out there that contradict each other. ",
"Also, ",
"this article",
" shows that naproxen does affect the clotting process by inhibiting the formation of thromboxane A2 which is essenti... |
[
"Should I recharge a half-full battery?"
] | [
false
] | Specially a lithium-ion one that we find in electronic devices. I got a new Nexus 7, and I might only use 20% of the battery in a day. Should I be recharging at night? | [
"Theoretically, Every battery has some degree of memory. Thus, you should always charge it fully, and always let the battery totally die before you charge it.",
"This is plain wrong. Lithium-ion batteries ",
"have no memory",
". In fact, ",
"full discharge of Li-ion batteries hurt battery life",
"."
] | [
"The thing is, when the battery has reached 100% charge, the charging stops and no more heat is accumulated."
] | [
"Lithium-ion batteries are a bit different than the ones most people grew up with and require a different set of guidelines for use and care.",
"First off, storing a lithium battery at full charge reduces it's life, so leaving it on a charger 24/7 is a bad idea for overall life.",
"Secondly, they have no memory... |
[
"Do photons ever accelerate?"
] | [
false
] | null | [
"They can ",
" to accelerate, as their path, as seen by a distant observer, curves around massive objects. Similarly, if you watch a light signal pass a massive object, measure the distance it appeared to travel and the time it took to complete the trip, you'll find that it took longer than if it had traveled at ... | [
"The apparent slowing down of light in a medium is a consequence of absorption and re-emission of photons as they pass through. Any single photon is ",
" traveling at c."
] | [
"Its velocity is constant, but acceleration is a vector quantity, not a scalar",
"Velocity is a vector quantity as well. I think you're thinking of speed.",
"Changing direction at constant velocity is acceleration according to everything that I remember from physics. ",
"Again, speed. Also, everything you rem... |
[
"Why is it so easy for us to remember and describe images and sounds but so difficult to retain smells and scents?"
] | [
false
] | For example I was walking through an area of my local park and caught a wiff off something. I instantly remembered the smell (though I wasn't sure what it was) and then couldn't remember or mentally recreate the smell when I left that area. | [
"And a side quetion to this one, why are smells the most powerful reminders for something, like you remember a beautiful situation from smelling freshly cut grass, just because the lawn was freshly cut on that day? Sorry if I'm not doing the best job at explaining my question."
] | [
"The prevailing idea is that smell evokes emotion and memory strongly because of the olfactory system's location relative to the amygdala. The amygdala can crudely be looked at as the emotion and partially memory area of the brain (it is a particular type of memory more related to emotion and survival instincts tha... | [
"You can definitely train it, yeah. It's what you do when tasting wine. For an 'outsider' it might sound like gibberish or just people making stuff up to sound sophisticated (and probably it is a lot of times), but if you know your salt you would know what somebody is talking about. Say you would have two sommelier... |
[
"Is a global earthquake possible?"
] | [
false
] | With all this May 21st nonsense going around it made me wonder if a global earthquake is even possible, and if it is how could it happen? | [
"if you are talking about complete destruction from an earthquake, then no its not possible.\nEarthquakes generally happen at techtonic fault boundries. if you look at a map of the worlds techtonic plates you will see that in a grand time scale, the plates on one side of the world will interact with the plates on ... | [
"Not unless it is a VERY big impact. I suspect that impactor would have to be something Moon-sized or bigger. If you want to experiment with different types/sizes of impactors, this ",
"Impact Calculator",
" might be of interest."
] | [
"Yeah, thats my understanding as well. The only thing I could think that would be even plausible would be some kinda disturbance with the earths core. But I have no clue how or even if that could happen."
] |
[
"Could we easily spread life to another planet by sending a capsule filled with bacteria?"
] | [
false
] | In a recent post today, it said that rocks containing earth bacteria had flown to other planets outside our solar system from the the meteor strike 65 million years ago. Could we potentially do this ourselves by launching a big capsule filled with bacteria towards places like Gliese 581, Europa, and Enceladus, and act... | [
"When you contaminate Mars with Earth bacteria, then any further research on extraterrestrial life on that planet will stop being valid. "
] | [
"We could easily send them there. The problem would be getting them to survive there and reproduce. What would they use for an energy source, is there liquid water there (all organisms on earth require liquid water for life), could they live alone instead of in a web of organisms like almost all organisms on eart... | [
"Probably not \"easily\". If it is a lifeless planet then there is probably a reason for that. Conditions aren't very suitable for life. If there is life on the planet then the introduced life, unadapted to its new surroundings, is unlikely to be able to compete for resources against the other well adapted lifef... |
[
"How to use Schrodinger’s equation to find the probability of an electron at certain place in electron cloud ?"
] | [
false
] | null | [
"The solutions to the Schrodinger equation in coordinate space give you the spatial wavefunctions for the electrons. The squared modulus of the wavefunction is the probability density.",
"You now have a continuous probability density function for where the particle would be found if its position were measured.",
... | [
"I'm not really sure how to answer this, since it's really the kind of thing that if you don't know the answer then you probably won't be able to make heads or tails of the answer. ",
"However, assuming you do have the requisite background in the necessary math, the time-independent Schrodinger equation is an ei... | [
"No their square is a probability density, their square AT A POINT is a probability, which, of course since position is continuous, will be zero unless you integrate over some finite volume."
] |
[
"Windows 10 says pins are safer than passwords how can this be when passwords have more combinations?"
] | [
false
] | null | [
"Pins aren't to increase the security of your machine, they are to increase the security of your microsoft account. ",
"Pins are for logging into the particular machine/account combination, and passwords CAN be for this, but also can be (and what microsofts wants) be multiplatform/cloud based (microsoft account)... | [
"This needs to be at the top. The PIN is only for the computer, and is bound to the computer alone.",
"You can log into a Windows 10 machine with your Microsoft account and associated password. Once you've authenticated yourself, you can then set up a PIN on the device to log into your MS account on that computer... | [
"It's a marketing thing, in reality the average user of Windows 10 when prompted to set a PIN will end up using their credit or debit card PIN. Not good for your bank security.",
"A well chosen classic password will always be stronger than a 4 digit PIN."
] |
[
"What exactly is it about alcohols that make them liquid at room temperature?"
] | [
false
] | If you have etOH at standard conditions, you have a liquid. If you remove the hydroxyl group, you have ethane, which is a gas. Is it the alcohol group which causes the chemical to be a liquid at standard conditions? Are there any other rational behind it? | [
"Hydrogen bonds. Same thing that makes water a liquid at room temperature makes alcohols liquid. "
] | [
"Alcohols all contain the OH-group, with the oxygen being partially negatively charged and the hydrogen being partially positively charged. Inside the liquid (as well as in the solid/gas) phase, the positive hydrogen interact with negatively charged oxygen on neighbouring molecules. This interaction is attractive a... | [
"The -OH or hydroxyl group that all alcohols have is what makes them a liquid at room temperature. There is a significant difference in electronegativity between H and O, so oxygen tends to hold the electrons shared between it and H much closer to the O atom. As a result the H atom has a somewhat positive charge ... |
[
"What experiment am I thinking of?"
] | [
false
] | null | [
"Mercury(II) thiocyanate AKA Pharoah's Serpent?",
"http://www.youtube.com/watch?v=yN9pioJWTk0"
] | [
"Yea, that's the stuff! My thanks, friend."
] | [
"You are probably thinking of burning of ",
"Mercury(II) Thiocyanide ",
"."
] |
[
"What makes water such a good solvent?"
] | [
false
] | What is it about water that means so many different substances dissolve in it? EDIT: Wow, I didn't expect so many answers! Thank you for taking the time to explain it to me (and maybe others)! | [
"It has to do with polarity. The small water molecules have different electrical charges at each end which means that other polar molecules can dissolve in it.",
"Apolar molecules, like oil, cannot dissolve in water but will dissolve in other apolar liquids like gasoline. Apolar molecules do not have different el... | [
"It's not just about polarity. It's also about hydrogen bonding and hydration shells, as well as the two lone pairs that are so free to generate hydrogen bonds. Think, for example, about the hexagonal structure of ice and how it could fit molecules or ions in there. That kind of happens with the hydration shell of ... | [
"Rule #1 of solution chemistry: Like dissolves Like.",
"You can group substances into roughly three major categories:",
"Nonpolar substances have a uniform charge distribution. This means that the electrons that make up their bonds do not tend to clump up in any particular areas. Oily substances are basically n... |
[
"Considering that the sand dunes in deserts move like water in slow-motion, would it be possible to calculate it's motion through Navier-Stokes Equation?"
] | [
false
] | null | [
"Granular flows are similar to fluid flow but cannot be modeled solely by the Navier-Stokes equation. Specifically the viscosity term is different because for sand the inter-particle interactions are are governed by friction and collision. A pile of sand can have a stable configuration with a sloped surface (whic... | [
"Probably not what a fluid dynamicist would call turbulence but certainly the potential for chaotic regimes."
] | [
"Do granular flows exhibit turbulence?"
] |
[
"Do fungi have immune systems?"
] | [
false
] | null | [
"Fungi use a system of protein receptors which can identify foreign matter in a manner similar to plants and animals.",
"\"A class of cytosolic Nucleotide Oligomerization Domain (NOD)-like receptors, or NLRs, contribute to this recognition and discrimination process in plants and animals [2,3]. Less is known abou... | [
"\"Heterospecific nonself\". I'm going to casually insert that into conversation today."
] | [
"They won't have anything like the vertebrate adaptive immune system, but they do have a variety of immune defenses. They can use ",
"RNA silencing",
" to control viral infections, and of course fungi are famous for producing antimicrobial compounds to fight off bacteria...most notably penicillin. Many of tho... |
[
"4 Physics Questions"
] | [
false
] | 1) It seems strange to me that at a fundamental level physicists don't explain a mechanism behind relativity. Is this just not widely discussed? Are there proposed mechanisms, but the even the question of a mechanism is too abstract to pin down any real ideas? Is relativity only an effect of the geometry of the univers... | [
"Geometry. It all stems from the very special relationship that time and space have together. Let's take a simple case. If you want to know the distance between two points in 2 space dimensions, you take sqrt(x",
" +y",
" ) where x is the distance in one space, and y is the distance in the other. But if you wan... | [
"1) You're going to have to define \"at a fundamental level\" for me. The way that fundamental physics works is that you observe some phenomena, you make up a theory that explains the structure of the phenomena consistently, and then you check that your theory predicts everything you observe.",
"General relativi... | [
"Curses! You beat me to this by 17 minutes. I was typing for a long time."
] |
[
"Could any biologists help me with this question about penguins?"
] | [
false
] | null | [
"Hi Al_Rapee thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the follow... | [
"Biology"
] | [
"‘Biology’"
] |
[
"Do dogs really learn words? Or do they just learn tone of voice?"
] | [
false
] | null | [
"Very interesting: ",
"Nova did a documentary on dogs recently, I can't recall if that clip was from this episode or from on of those nova science now episodes.",
"http://www.pbs.org/wgbh/nova/nature/dogs-decoded.html"
] | [
"Very interesting: ",
"Nova did a documentary on dogs recently, I can't recall if that clip was from this episode or from on of those nova science now episodes.",
"http://www.pbs.org/wgbh/nova/nature/dogs-decoded.html"
] | [
"Very interesting: ",
"Nova did a documentary on dogs recently, I can't recall if that clip was from this episode or from on of those nova science now episodes.",
"http://www.pbs.org/wgbh/nova/nature/dogs-decoded.html"
] |
[
"Where did the moon come from?"
] | [
false
] | I've heard two theories. One is that the moon accreted along with the earth during the formation of the solar system. The second is that a Mars sized object collided with the proto-Earth and ejected enough material into orbit that eventually coalesced into the moon. I seem to remember a recent article that says the moo... | [
"It is pretty much accepted that a Mars sized object hit the Earth at a glancing blow. ",
"Wikipedia"
] | [
"Yes yes, internet meme, blah blah blah. But it's actually a good question and it deserves a serious answer. And yes, I agree that it's pretty much accepted nowadays that the Moon was formed from a collision in the early solar system. ",
"(Also, internet memes these days suck. In my day we would have said that th... | [
"Yes yes, internet meme, blah blah blah. But it's actually a good question and it deserves a serious answer. And yes, I agree that it's pretty much accepted nowadays that the Moon was formed from a collision in the early solar system. ",
"(Also, internet memes these days suck. In my day we would have said that th... |
[
"How long are acidic/spicy things like Orange Water or Enchilada Sauce safe to eat in the fridge?"
] | [
false
] | I've got some spicy Enchilada sauce with a pretty darn acidic PH, that's literally 6 months sitting in the fridge, as well as some orange water (4 slices of a large orange, pre-washed and scrubbed with soap, and then added to about a pint of water and has been sitting in my fridge for two weeks. Is the acidity of such ... | [
"DOH! I meant 'eat FROM the fridge.' That was such an epic failure, given that this ",
"/r/askscience",
". Forgive me, oh dogs of grammar.",
"Also some clarification: The orange itself is washed before slicing, no washing of the slices themselves, that would be just rather odd."
] | [
"As a general rule, if it smells fine, looks fine, and tastes fine, it's probably fine. There aren't any stealth spoilage bacteria that creep into things the minute they hit their expiration date, so you don't need to worry about suddenly dying.",
"From personal experience, chili pepper sauces will pretty much ne... | [
"As a general rule, if it smells fine, looks fine, and tastes fine, it's probably fine.",
"True, but botulism is a very important exception. It doesn't like acid, though."
] |
[
"Idle Speculation on a Geoengineering Question"
] | [
false
] | Forgive the speculative nature of this question. I imagine this is wholly implausible; mostly I'm asking because I'd like to learn more about how modern lasers transmit information through the atmosphere, how railgun technology has advanced in recent years, and whether it could serve as a viable satellite launching tec... | [
"Rail guns only require the projectile to be conductive, the magnetic field is generated by the current passing through the object."
] | [
"Lasers are subject to atmospheric distortion.\nRailgun technology has increased as much as capacitor technology - they are dependent on the capacitors for the high voltages required. The US Navy is the largest researcher."
] | [
"Launching with lasers is described in ",
"The Millenial Project",
", an interesting book on terraforming. The author suggests initially accelerating ships like a railgun and launching them out of Mt. Kilimanjaro. Then, many large microwave lasers would ablate a large block of ice under the space vessel witho... |
[
"When the first nuclear submarine, the Nautilus passed under the North pole in 1958, how did they know there is enough room for it between the sea floor and the bottom of the ice?"
] | [
false
] | It was occasionally a close call, so did the Captain of the sub knew in advance the gap's size and that the sub has enough space? Edit: After learning more about the Poles, the correct answer is that there is no continental shelf under the North Pole and the Arctic sea's depth is 4.2 km there. The ice is only about 2 m... | [
"They had been using sonar both active and passive on submarines for a long time. They can hear how far it is from the bottom and the ice sheet. It was also definitely not the first venture of a sub under ice. Just further and longer than they have gone before."
] | [
"Sounding below the ice have been taken all across the artic. Even then they had a decent idea of the topography. It has long been known that the artic was an archipelago."
] | [
"How did they know it was feasible at all?",
"Do we actually know that they knew for sure that it was possible? It seems to me that one of the reasons you might send a sub under the North Pole is to find out if it's possible to move subs around down there. After all, exploration is often less about what you kno... |
[
"What triggers Apoptosis in the human body?"
] | [
false
] | What makes certain cells kill themselves in Apoptosis while other types continue to reproduce? If its a chemical trigger can we reproduce it artificially to target specific cells such as cancer? | [
"I'll just quote the introduction of my thesis proposal.",
"Apoptosis is a highly conserved function by which individual cells can initiate and control the process of their own demise. An essential process throughout multi-cellular organisms everywhere, apoptosis is critical for the timely destruction of damaged ... | [
"All cells follow a predetermined growth and reproduction cycle, and there are certain chemical triggers that the cell recognizes at 3 points during the cell cycle, if a cell is damaged it will tell will not allow itself to build some of the proteins crucial for mitosis. Some stop reproducing, others stop functioni... | [
"Some. It gets complicated. The main pathway for apoptosis involves a series of enzymes called caspases, and these are activated by (among other things) calcium. So large influxes of calcium can cause apoptosis. In the brain during prolonged seizures, for instance, neurons may die because of energy failure (in whic... |
[
"Is it actually possible to \"inhale\" a disease from somebody who is infected?"
] | [
false
] | For example, TB or Tuberculosis... can you get TB from inhaling the air around a person who is infected? | [
"You don't get diseases from air, you get diseases from inhaling viruses or bacteria that are ",
".",
"Any \"air borne\" disease can become suspended in air and can be transmitted by inhaling air that contains that particle. ",
"Some examples include the common cold, flu, and yes, TB."
] | [
"There is a subtle difference in transmission between TB and the cold or flu. TB is truly airborne which means it can hang out in the air for a long time, like dust. The infectious aerosol can remain in the air even after the patient is long gone, and can even travel on air currents to other places. The cold and fl... | [
"Yes, definitely. I did not think the difference was substantial enough to explain the difference. "
] |
[
"What's the relationship between sharpness and hardness? Could a sharp enough blade cut through steel a la Snow Crash?"
] | [
false
] | In Snow Crash, Raven would use blades a molecule thick at their edge to cut through material far harder than the blades were made of--say obsidian cutting through steel. Is such a thing possible? More to the point: what, if any, is the relationship between hardness and sharpness in determining if something gets cut or... | [
"How sharp a material is will define how neat the cut will be, but beyond that has very little bearing on deciding what cuts what.",
"Hardness is the variable you're looking for if you're trying to decide if something will cut something else. Simply put, hardness is a measure of how much force a material can take... | [
"No, such a thing is not possible with current materials. Raven's blades were a molecule thick at the edge, but they didn't cut through steel. Read the book again, they cut through things like human flesh and bullet proof vests. That's not really surprising, though, as steel knives will also cut through kevlar w... | [
"Just throwing out ideas;",
"Maybe the better question involves edge geometry instead of just sharpness. Just throwing out ideas here, but it seems intuitive that a Raven style blade would allow for more shearing (as opposed to ploughing) at the cut. Furthermore, at the microscopic level where the contact actuall... |
[
"Is it easier to get food poisoning when on a course of Antibiotics or more difficult?"
] | [
false
] | If I was on a course of Antibiotics would their presence in my body help fight of the bugs of bad water or fish? Or would my lack of gut bacteria due to being on antibiotics help the germs flourish in an open game? | [
"Classic food poisoning is not actually caused by infection, rather the symptoms of food poisoning are typically due to the ingestion of bacterial toxins that are present in the environment. So in these cases, antibiotics won't do anything because no infection is necessary to cause the illness. Classic food poisoni... | [
"This is just too broad of a question for a specific answer. For one thing, \"food poisoning\" refers to an incredibly varied set of situations. ",
"Mycotoxins are produced by fungi that grow in stored food, and can cause serious illness even though the fungi themselves do not survive the cooking/digestion proces... | [
"I have to clarify one part of your answer there. While you are correct in saying that often people are made sick by bacterial toxins it looks to me like you're saying that those toxins are just hanging out in the environment and a person can become sick just by say drinking a glass of water with the toxin in it. ... |
[
"Step Function Symbol"
] | [
false
] | Picture: Our lecturer has awful handwriting, his notes are one of the reasons our year is going to fail (see above link for example). In the above link, the symbol outside the brackets for unit step function is unknown. Literally 200 students have no idea what symbol it is meant to be. All we know is that its somethin... | [
"Sometimes it is marked as \"1\"",
"Seriously? That's the worst abuse of notation I've ever seen, and there are a ",
" of abuses out there."
] | [
"The last one is probably a delta function, which is the \"derivative\" of the step function. The step function is usually represented by a H in physics, but I guess he meant a 1"
] | [
"I would email him if you are too worried about it. But given the context of the other functions I would say its probably the Heaviside function, especially if he told you the derivative of the 'uknown function' gave you a \"dirac impulse.\""
] |
[
"Is quantum phenomena the only example of a truly stochastic system?"
] | [
false
] | It seems to me that, at a macro level, if there is enough information about a system, that it can be entirely deterministic. I am aware of the "Hidden Variables" conjecture, and that it is countered by Uncertainty and Quantum Mechanics. My lab mates have cited Entropic systems as a macro-level system, but I (maybe fals... | [
"So a rephrasing of my question is: If the output of all quantum phenomenon in a system is somehow known ahead of time, can every system be determined from a starting state?",
"Yes. ",
"Let's say you assume the MWI of quantum mechanics, which insist the schrodinger equation is universal. The schrodinger equatio... | [
"I'm sure there are examples of larger thermal systems that behave truly stochastically but these are two that immediately come to mind.",
"You cannot get true randomness if the underlying physics is deterministic. I'm not familiar with your area, but if you're using a classical description that contains true ra... | [
"In many classical problems, an ",
" small change in the initial conditions of a system can result in a totally different outcome over time. The word \"infinitesimal\" is not to be taken lightly. No matter how well you define your initial conditions, it is always the case that subtle differences in those conditio... |
[
"How does a catalyst affect activation energy?"
] | [
false
] | I have seen diagrams of catalysts which hold molecules in place so that they are in the correct orientation for reactions to occur but my textbook says that they provide a alternative route which lowers activation energy. Does that mean orientation is factored into activation energy or are they separate things? If so h... | [
"As an example, for a reaction with one intermediate state the activation energy is the energy required to reach that state. A catalyst changes the intermediate state in a way that the energy required to reach it is reduced.",
"A simplified (and not necessarily correct) view of the oxidation of hydrogen on a Pt s... | [
"I'll try and give a biochemical perspective, as catalysis is fundamental to biology. The activation energy of a reaction refers to the energy needed by a given chemical species to reach its reactive state. Typically, this energy is used to overcome some kind of steric hindrance. (As you suggested, the electrons in... | [
"Don't worry about kinetic energy for the moment. The potential energy associated with the bonds is what we care about.",
"Breaking these bonds requires energy. In some cases, less energy is required to break bonds when the molecule is 'bonded' (to differing amounts) to a surface. H2 dissociation on Pt is an exam... |
[
"Are there lifeforms with translative joints ?"
] | [
false
] | So I noticed that every joint in the human body is based on a rotation, the only difference between them being the number of liberties (for example : elbow and knee : 1, neck and ankles : 3). I've thought about pretty much every living species I could think of, and all of those which have joints have, I think, rotative... | [
"Would you consider that a joint? That is the mechanism of the molecular motors (related to ATP synthase motors), but it isn't really a joint like those of an animal's arms and legs."
] | [
"Yes there are, a sperm's tail can rotate clockwise and counterclockwise without a stop ",
"http://en.m.wikipedia.org/wiki/Flagellum#section_1"
] | [
"You're right, but I was thinking about something macroscopic."
] |
[
"How did monkeys get to the new world?"
] | [
false
] | How did monkeys get from Africa to South America? I'm actually writing a research paper on it and two theories I have found are the drifting theory in which a giant tree brought them across the ocean, or the Antartica theory which has been pretty discredited. I need sources to for my bibliography so if anyone has lin... | [
"AFAIK, the raft of vegetation is the best (only?) theory out there. Even though the Atlantic Ocean was narrower about 40 m.y. ago (around 1000 miles at the narrowest), it seems a remarkable journey."
] | [
"You want aliens just watch the history channel. But rafting is the going theory. Here's an article (the bit about rafting is down toward the bottom, and mentions some other groups thought to have rafted) ",
"http://blogs.scientificamerican.com/tetrapod-zoology/2011/10/05/hoatzins-in-africa/"
] | [
"Thank you. It sure is remarkable, when it was explained to me I was like, \"You really expect me to believe that?\" But that is the best hypothesis out there. Still searching for articles that support electromagnetic anomalies or even better... ALIENS! "
] |
[
"Why does the shower curtain get 'sucked' inwards when you turn the shower on?"
] | [
false
] | Edit - thanks for the answers everyone! I still find myself curious, there's been lots of different principles given as answers... | [
"A minature sideways huricane",
"http://www.scientificamerican.com/article/why-does-the-shower-curta/"
] | [
"Because the water flow is also dragging air along with it, creating an air current. If you remember your physics class, or if you've ever studied how airplane wings work, you'll be familiar with the concept at work here. ",
"To put it in simple terms, air that is moving quickly has a lower pressure than air that... | [
"While that is a contributing factor, the same phenomenon can be observed when cold water is used."
] |
[
"Does temperature affect cellular signal?"
] | [
false
] | [deleted] | [
"It shouldn't be a significant factor. I believe that this battery depletion is due to some other effect. Not temperature related impact on the reception."
] | [
"Temperature does affect the resistivity of conductors but that doesn't usually impact signal processing and transmission because the information flow is not proportional to the charge flow but rather information flow. "
] | [
"Temperature does affect the resistivity of conductors but that doesn't usually impact signal processing and transmission because the information flow is not proportional to the charge flow but rather information flow. "
] |
[
"Is there a sweet spot on any of the gas giants where we could float something like a blimp?"
] | [
false
] | If so, could there be the possibility of a maned mission some day that does just that (other than first testing the idea with a probe)? | [
"Kind of relevant xkcd"
] | [
"So this idea has been explored somewhat extensively. ",
"This PDF",
" gives a decent insight into some preliminary mission planning for an aerobot that could be used on Jupiter.",
"Technically speaking, a \"blimp\" itself would never work on Jupiter. Blimps work on the principle that you maintain buoyancy by... | [
"So, uh, scientist who actually studies Jupiter's atmosphere here...",
"Atmospheric pressure is about 10 bars at the start of what we consider Jupiter's atmosphere",
"That should read ~1 bar, not 10. Earth's pressure at sea level is 101.3 kilopascal, and 1 bar is defined as 100 kilopascal. Based on our best est... |
[
"Is there a nearby neutron star / pulsar associated with the supernova that created the heavy elements found on Earth?"
] | [
false
] | We know that all of the elements on the periodic table with an atomic number greater than iron are created from supernovae events. Therefore, much (if not all?) of the matter in our solar system is made up of material left over from a supernova in our cosmic past. We also know that neutron stars are the stellar cores l... | [
"So anything greater than about 8x the mass of the sun will explode in a supernova. This means that the remnant can be either a black hole or a neutron star. (Though Neutron stars are way way way cooler.)",
"The seeding of the milky way to produce metals did not come from just one supernova. It came from many sup... | [
"Also, a supernova imparts a large kick to the remnant.",
"Just to chip in on this...neutron stars are kicked randomly out at a few hundred kilometers per second from an exploding supernova. The solar system is about 5 billion years old, so the neutron star could have gone a couple million light years in this tim... | [
"Does this imply there is a neutron star somewhere in our cosmic neighborhood associated with the supernova that generated all of the heavy elements found in on Earth? If so, have we identified the location of this neutron star?",
"The solar system is about 4.5 billion years old, and it takes about 230 million ye... |
[
"Does hot water flow faster than cold water?"
] | [
false
] | [deleted] | [
"It can flow marginally faster while remaining laminar(smooth) rather than turbulent. This is defined by the Reynolds number and is proportional to density and viscosity which both reduce with higher temperature. Lower Reynolds is less turbulence. Water is liquid over a narrow range of temperature though. "
] | [
"The viscocity of water varies by about a factor of 3 between room temp and boiling point. "
] | [
"The thermal particle motion you are referring to is random, there are just as many particles moving \"forward\" as there are \"backward\", so the net effect is zero.",
"Two potential effects on flow due to temperature are:",
"If the flow is driven by a constant pressure difference (eg, water flowing down a hil... |
[
"What does a black hole look like?"
] | [
false
] | null | [
"Like a black circle which lenses background light around itself. Probably something a bit like ",
"this artist's rendition",
". That's assuming it's just a black hole with no accretion disk.",
"The event horizon of a black hole describes a spherical shape in space."
] | [
"Think of the gravitational field of a star or planet. In the same way, a black hole's gravitational field is spherical. conservation of momentum tends to form the accretion disk into a flat shape, though."
] | [
"Okay, it makes sense now! and that's a really cool picture. Thanks! "
] |
[
"Do other species have cultures?"
] | [
false
] | Humans have a wide variety of cultures in different areas. Do other widespread species have similar cultural variation? I've heard examples of a certain group of predators developing a hunting technique that other groups don't use, but how far does this go? Which other animals present wide variation within the species ... | [
"Many cetaceans (whales and dolphins) have been demonstrated to have cultural differences in behavior. This can include hunting and foraging behavior, communication, and social interaction.",
"Groups of the same species in different regions often have widely varying behaviors. For example, Killer whales (",
") ... | [
"Chimpanzees have many well documented forms of culture. Most of it comes from differences in tool use or communication. Chimpanzee populations that are isolated from one another tend to develop cultural differences. They learn the techniques from others within the group",
"http://www.sciencedaily.com/releases/20... | [
"http://www.youtube.com/watch?v=bXQAgzfwuNQ",
"This is just one example of species having idea sharing!"
] |
[
"How are HELA cells immortal?"
] | [
false
] | null | [
"This answer is incorrect.",
"The end replication problem that you describe applies to (as the name strongly suggests), replication, not transcription (the process you describe) and especially not translation (which does not involve DNA at all). As well, RNA polymerases ",
" attach to single-stranded DNA. Prima... | [
"This answer is incorrect.",
"The end replication problem that you describe applies to (as the name strongly suggests), replication, not transcription (the process you describe) and especially not translation (which does not involve DNA at all). As well, RNA polymerases ",
" attach to single-stranded DNA. Prima... | [
"They are cancer cells. Cancer cells generally are immortal. But obviously, that doesn't really answer the question.",
"Cancer cells obtain immortality in the sense that they no longer have any limits to how many times they can replicate themselves, thus growing continuously (and why we can harvest enough cells f... |
[
"A question about relativity..."
] | [
false
] | I understand that all observers measure the speed of light as a constant, no matter how fast they travel, and that time slows down to ensure that you don't match or exceed the speed of light, but why does time dilation only affect one of the moving objects. If we had somebody get on a spaceship from earth, travel at 0.... | [
" isn't relative, and you have to accelerate to come back. That's the deciding factor."
] | [
"So my question is, how can we calculate absolute time dilation if all motion is relative?",
"The thing you calculate in this theoretical scenario is called the \"proper time\" along the trajectories of the two observers. The most convenient way to do this is to pick a single inertial reference frame in which to ... | [
"Wow, thanks a lot. If everybody explained things this well I wouldn't have had to ask the question in the first place."
] |
[
"Are there any benefits from eating sugar?"
] | [
false
] | [deleted] | [
"Sugar's not harmful if you don't overdo it, but it wouldn't hurt to leave it out altogether. You get plenty of sugars in almost all the food you eat, unless you only eat whale blubber. Even proteins can be converted into sugar by your body if the need arises."
] | [
"Glucose in particular is extremely important to the function of the human body. ",
"Hypglycemia",
", or low blood sugar, is a condition that wreaks all sorts of havoc on normal brain function. Fortunately, as mutatron said, most everything you eat can be used as a glucose source by the body, so you don't nec... | [
"Sugar is not harmful if used in moderation, but this can be said about everything. In excess it can be converted to fats for storage. So if you take in more than you use, you'll get fat. Also, excess sugar floating around in your blood can cause damage (the same damage that results from diabetes).\nGlucose is not ... |
[
"In string theory, if strings are 1-dimensional, how do they vibrate in more than 1 dimension? E.g. If a piece of paper (defined by dimensions ,y) was truly 2 dimensional, could you bend it along the z-axis?"
] | [
false
] | typo: ...(defined by dimensions x,y)... | [
"They vibrate in the dimensions orthogonal to its length, called transverse dimensions.",
"They can because they are elastic! Paper is not analogous because it's not elastic."
] | [
"No, the string is vibrating in the transverse dimensions. The string is ",
" a background spacetime and moves in it. It's really like a normal guitar string.",
"Now for the advanced part: the curvature of spacetime has actually an equivalent (dual is the best word) description in terms of virtual gravitons. Bu... | [
"No, the string is vibrating in the transverse dimensions. The string is ",
" a background spacetime and moves in it. It's really like a normal guitar string.",
"Now for the advanced part: the curvature of spacetime has actually an equivalent (dual is the best word) description in terms of virtual gravitons. Bu... |
[
"What causes shivers when you pee sometimes?"
] | [
false
] | [deleted] | [
"Ahhh the good 'ol pee shakes, or, rather \"Post-Micturition Convulsion Syndrome\". This is completely unknown cause but is thought to be part of a sympathetic reflex of your sacral portion of the spinal cord to the pedundle nerve during micturition. "
] | [
"what about poop shivers?"
] | [
"I was always told it means that a bunny ran over your (future) grave"
] |
[
"If this graph from NASA is used to show that global warming is occurring, what was going on before 1940?"
] | [
false
] | null | [
"The line in the middle of the chart is the average temperature during this time period. Because the temperature has been increasing, this is above what the old average would have been. The average looks like it would have been around -0.25 C, with regular yearly fluctuations occurring throughout."
] | [
"I'm not sure what you're asking. Can you elaborate on your question or explain what has you confused? Also, can you link us to where this graph is from?"
] | [
"Warming was still occurring prior to 1940, but to show increases in temperature, we subtract a time period in question relative to another time period, which is usually 30 years. ",
"For example, the recent release of the ",
"National Climate Assessment",
" will usually use a base period of 1980-2010. Temper... |
[
"Can you recommend a good book that explains an area of complicated science in layman's terms?"
] | [
false
] | null | [
"Oh, hey, also do a search in AskScience (make sure the checkbox is checked) for \"books\". There are quite a few threads there that did get some traffic before we became despots. "
] | [
"We are going to do a little special on this topic soon, so stay tuned!"
] | [
"Haha did you remove my post from public view? I was wondering why I couldn't see it on the \"new\" thread. And how will I know when you do the special/where to find it?"
] |
[
"Electro-Convulsive Therapy - how does it work?"
] | [
false
] | [deleted] | [
"I will assume you mean ECT for the treatment of severe major depressive disorder. As far as I am aware this is the primary indication in the modern age.",
"The short answer is nobody really knows. ",
"Here",
" is a PDF of an overview of proposed mechanisms of action. (It's fairly technical.)",
"The goal of... | [
"There was research published about ECT just this week. ",
"1",
", ",
"2",
"."
] | [
"I not familiar with the details but what I do know is its overdramatrized in films. Those \"shocks\" are very short, like a defibrillator. Exposure to current through the brain for any period of time can be very lethal, keep in mind. As for how it works, as I understand it puts the patient into a small seizure and... |
[
"How was the first computer OS created without another OS to create it on?"
] | [
false
] | null | [
"The first computers didn't have operating systems, they just had dedicated programs that performed specific functions or would have programs and data loaded using punch cards. These were written manually.",
"Predating operating systems were assemblers and compilers that allowed for simple programming languages. ... | [
"This is like asking how a house knows how to stand upright when you put nails in 2x4s and build a frame...",
"A processor is a processor because we designed an electrical circuit to respond to stimuli in a given way. If I tell it to load 23 in the A register it puts 23 in the register because that's what the ci... | [
"At its core, a CPU is just a complex circuit that when given certain inputs produces some output or performs some action. At the lowest level, there is memory that stores instructions for the processor, encoded as ones and zeros, that tell it to perform some operation. ",
"One such simple operation is to move da... |
[
"In the electromagnetic spectrum, what do you get at frequencies higher than gamma rays?"
] | [
false
] | What is the result of electromagnetic radiation at a frequency greater than that of gamma rays? It seems that as the frequency increases, it interacts more strongly with matter. Does this continue? | [
"What is the result of electromagnetic radiation at a frequency greater than that of gamma rays?",
"In proton-proton collisions many neutral pions are produced which predominately decay into high energy photons. At LHC energies, these photons can range into the 100 GeV range. As far as I know, these are just call... | [
"Indeed.",
"Also, very high energy photons tend to \"leak out\" their energy as they travel through the universe:",
"http://en.wikipedia.org/wiki/GZK_cutoff"
] | [
"They turn into e+/e- pretty quickly assuming that they are in some dense material like lead (on the order of centimeters), but otherwise they can travel a long distance before 'converting'. Conservation of energy-momentum prevents them from converting without exchanging momentum with a nearby charged particle. ",... |
[
"Could an orb of photons orbit a massive enough object?"
] | [
false
] | If you had a massive ball of photons traveling at the speed of light at the proper trajectory could they orbit a massive enough object? I'm assuming that this object would have to have more mass/be dense enough to surpass any known black hole. I would also guess that the ball of photons would be invisible since none of... | [
"A massive ball of photons doesn't really make sense, but for individual photons it is called the ",
"photon sphere",
"."
] | [
"Every black hole has a region around it where photons are trapped in orbit."
] | [
"Similar"
] |
[
"Why are men better than women at chess at the elite levels?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"statistically",
"If you disagree with this decision, please send a ",
"message to the moderators."
] | [
"Thank you for getting back to me but that does not seem to cover why men are better at the elite levels. "
] | [
"Thank you for getting back to me but that does not seem to cover why men are better at the elite levels.",
"Please direct your objections to the authors. Thanks."
] |
[
"Why is it that some dyes, like that used in laundry detergents, do not stain [white] clothes and can actually do the opposite, clean them?"
] | [
false
] | The question popped in to my head as I poured a popular detergent in to my washer containing white clothes and I noticed how dark blue the detergent was, completely opaque, and I found it odd that it cleans as opposed to leaving a dreadful blue splatter all over my clothes. | [
"I work in textiles so I can answer this question:",
"When you are using a detergent, especially for whites, the blue color most likely comes from the optical brighteners that are in the detergent.",
"Modern detergents have a number of active agents. They have surfactants such as SLS (same as your shampoo or li... | [
"Hey I have a related question you might be able to help me with!",
"What are some good anti-foaming agent for SLS? It was a problem I came across at work last year and I did't have time to track down a good answer, only a few generic lists of anti-foamers to try."
] | [
"I actually don't. We did a bit of anti-foaming stuff for the mining industry back when I was in uni but I wont be much help. Perhaps look at what they have in dishwasher liquid vs the regular dishwashing soap. "
] |
[
"With solar sails being so thin, how do they avoid being punctured by tiny space debris?"
] | [
false
] | null | [
"Answered for the Planetary Society's LightSail project at ",
"http://sail.planetary.org/faq.html",
". Their sails use rip-stop construction so that a pinhole doesn't develop into a large-scale tear, and they can accept several localized holes without losing mission effectiveness."
] | [
"To add to this, protecting the sails from debris would not be feasible. ",
"This is what happens when something gets hit by space debris"
] | [
"I'm pretty sure there is always a chance of a space pebble killing everyone."
] |
[
"What type of wire should I use for high-T petrological experiments?"
] | [
false
] | null | [
"Not the right sub. Maybe try ",
"/r/labrats",
" or ",
"/r/askchemistry",
" or another more specialized sub"
] | [
"Thanks, I've tried both of your suggestions. Could you explain why this isn't right for AskScience? I don't see anything in the guidelines that could disqualify this. \"Chemistry\" is definitely too broad of a flair for such a question, but I don't see anything better suited, such as \"Materials Science\"."
] | [
"This sub isn't the right forum for project or research help. There are other, more specialized subs that might be more appropriate."
] |
[
"Spherical universe and relativity"
] | [
false
] | Although my understanding is that measurements are pointing towards the universe being flat, how would the "paradoxes" of relativity (both watches going slower than the other, both twins being older than each other) work out if the universe were shaped like a sphere or other closed object? The other person wouldn't hav... | [
"Not really, no. In this context, we have to talk about ",
" trajectories, not merely spacelike trajectories.",
"In a Minkowski universe, there is, at most, exactly one inertial trajectory between any pair of events. An inertial trajectory is, in practical terms, any one along which no acceleration will be meas... | [
"Have a look at this ",
"old post",
"\nIt should answer most of your questions."
] | [
"I read most of the ",
"paper",
" linked in one of the comments, and so to make sure I understand correctly: The twin paradox doesn't directly translate from \"go somewhere, come back\" to \"go around the universe\" because the paths are not really the same; the second path \"goes around\" and therefore can't b... |
[
"What is the long term effect of human growth hormone?"
] | [
false
] | [deleted] | [
"There was a lot of buzz about it that basically amounted to nothing. In people not deficient (the majority), all it really does is increase lean muscle mass and decrease fat content without any increase in strength. This is interpreted as increased water content in the muscles. So I suppose it'll make you look a l... | [
"What about people who are deficient?",
"When I was a kid I took growth hormone shots, but stopped taking them when I was about 17. In college I was a summer camp counselor, and by coincidence, one of my campers took HGH. I spoke to his mother when she came to pick him up and she said that he would be taking the ... | [
"\"",
"Acromegaly",
" \n is a syndrome that results when the anterior pituitary gland produces excess growth hormone (GH) after epiphyseal plate closure at puberty\"",
"This wikipedia article explains the long term side effects of too much GH, especially after the growth plates in many bones have fused. Altho... |
[
"What is the science behind acne, and how do products work?"
] | [
false
] | [deleted] | [
"There's actually a lot of research going on regarding acne, due to the high prevalence in society (something like 80% between 12-24yo). The disease process starts with an abnormal proliferation of the keratinocytes (skin cells) that line the top of a hair follicle. This results in blockage of the follicle, as we... | [
"Are you able to provide any sources? I'd like to learn more."
] | [
"Resource from another redditor; fairly comprehensive. ",
"Link"
] |
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