title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Since we are in the Milky Way galaxy, how do pictures of it exist and how come some have seen it?"
] | [
false
] | null | [
"Astronomy"
] | [
"Astronomy"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"You question is either commonly occurring or has been recently posted on ",
"/r/AskScience",
". It may also be answerable using a Google or Wikipedia search.",
"To check for previous similar posts... |
[
"Medical question: What is the best way to know if someone has a gag reflex before inserting an oral airway or intubating?"
] | [
false
] | As an EMT, I was taught I could brush the patient's eyelashes before sticking an oral airway in their mouth, or intubating them. If they don't blink or twitch, "they don't have a gag reflex" and it's safe to go ahead and intubate. The eyes and face are controlled by Cranial Nerve V and VII, whereas the gag reflex is co... | [
"Generally, if the corneal reflex (CN VII) is gone, the gag reflex is gone. You don't lose pieces of your brain individually unless you have an embolic shower or something, and that's pretty rare. When we check corneals after induction anesthesia before intubating, it's just an easy way of probing brainstem reflexe... | [
"I've been a paramedic in the Dallas area (i.e., a busy system with ",
" intubations) for nine years and the eyelash test has never given me a false positive. I see what you're saying with the different cranial nerves, but a comatose patient is a comatose patient."
] | [
"You can tell pretty quickly whether someone has a gag reflex or not when you try to insert the OPA in. There's not much of a grey area. They will cough, gag and fight it if they have a gag as soon as you try to insert it.",
"If they regain consciousness enough to maintain a gag reflex post-OPA the first thing th... |
[
"If someone was to 'swing' on a hovering helicopter would the opposing force cause it to crash?"
] | [
false
] | So I was watching the new Spider-Man movie and there was one scene where spider-man swung about a 120° swing, from a non-moving, hovering helicopter swinging at a decent speed of about 60km/h+. After the movie I had a disagreement with a friend on whether or not the helicopter would actually crash from such a swing. So... | [
"What of the tilt factor due to lateral forces?"
] | [
"All right, we'll shift the bottom of the 3.14m-high chopper 10cm, leaving the centre of the rotor in position.",
"cos",
" (10cm/314cm) is about 88 degrees. The helicopter is pushed two degrees off vertical.",
"Again, I don't think is enough to significantly foul the helicopter."
] | [
"Depends on many factors, including:"
] |
[
"Why do objects floating on the surface of water tend to attract and stick to each other?"
] | [
false
] | Hi AskScience, I was hoping that you can help my son and me answer this question. While eating breakfast this morning, my son noticed that when two (or more) cheerios floated near to each other, they seemed to get attracted together and then stay together, just like two magnets would. What is the name to this phenome... | [
"This gave me an idea. While water tends to cling up the side of a cheerio, a paperclip suspended on water pushes the water around it down. I decided to see how they would interact.",
"http://imgur.com/JY8no",
"They repelled each other to the distance seen in the photo."
] | [
"The interesting thing is that it is actually called the ",
"Cheerios effect",
"!",
"Basically it's due to surface tension and adhesion - water tends to cling onto the surface of objects, and having your Cheerios parked side by side allows water to rise up much further than if they're apart."
] | [
"Upvote for first-hand experimental evidence!"
] |
[
"Why do some photos of yesterdays eclipse show near total occlusion while others appear to show much less?"
] | [
false
] | Here are some examples: #1 #2 | [
"If you look at the photos supplied, one shows a very thin ring of light around the Moon, while in the other the Moon looks impossibly small. Technically these are both total annular eclipses since the disc of the Moon is completely within the disc of the Sun."
] | [
"Being inside or outside the band would not have such an effect on the apparent size of the Moon's disc as in the second photo. I question whether that one is even real. "
] | [
"Actually, I concur - the second picture is suspect now that I ponder on it.",
"For comparison here is ",
"yesterdays eclipse",
" from the Big Island.",
"However, a off-edge eclipse might look smaller simply because it is being more washed out by sunlight then a perfectly positioned eclipse - though not lik... |
[
"Do heavy elements like uranium sink to the center of the earth?"
] | [
false
] | Do heavy elements, like uranium sink to the center of the earth or does the convection of the liquid layer keep it mixed? Other forces I haven't thought of? Geologists of redit: I eagerly await your answer. | [
"Uranium is a ",
"lithophillic",
" element, meaning it forms oxides that tend to remain in the rocky crust and mantle rather than sinking into the iron core, so despite it's high density, it's more abundant in the crust than the core due to it's insolubility in iron. Plenty of other elements do sink into the c... | [
"u/Peter5930",
" is correct, it’s not just density but also chemical solubility which determines whether elements get sequestered into the core or not. This is encapsulated in the ",
"Goldschmidt classification of the elements",
". ",
"Some elements like uranium are soluble with silicates and so they will h... | [
"Iron is a very common element on Earth, early on when Earth was more liquid most of it sank down and took less frequent elements with it if they could dissolve in iron."
] |
[
"Why does life or why do with think life requires water?"
] | [
false
] | null | [
"The reason we can only imagine any life found in space to contain water is that every organism we currently know of is dependent on water for survival. ",
"Water plays a fundemental role in every organism. All living cells we are aware of use water in respiration or photosynthesis. Water is also essential in mos... | [
"The idea of a silicon based lifeform has been discussed, but there is no reason to think liquid nitrogen could perform the same role as water. It is far too stable a molecule to act as a solvent, meaning replication of genetic material could not ocurr. We also have the temperature issue that makes water so good. L... | [
"So basically it is just that is what we are familiar with. What about compounds with similar properties such as Silicon instead of carbon or a life form that uses liquid nitrogen instead of water?"
] |
[
"Why does your taste go bad when you are sick?"
] | [
false
] | null | [
"Do you mean your sense of taste? That actually depends a lot on your sense of smell. If your nose is stuffy, food will taste blander."
] | [
"Not necessarily, I have clear sinuses, but even water tastes gross."
] | [
"We don't really speculate about personal experiences. "
] |
[
"Why does the skull have indentations at the temples?"
] | [
false
] | null | [
"The indentations on the skull allow room for muscles which allow us to bite and chew. If you place your fingertips on your temples while you chew, you can feel the muscles flexing. If you compare a human skull with a gorilla skull, you can see that the gorilla has considerably larger chewing muscles, which attac... | [
"We actually do not have a ridge. Modern humans need much less biting power because we do not rely on tough vegetation, nuts, and seeds for our primary food sources. We need even less because our food is softened by cooking! It's one of the ways we can see the human lineage modernize from our more chimpanzee-like a... | [
"The indentation around the temple is what remains of a hole in the skull that has since been covered over in mammals. It initially formed in synapsids as an ",
"anchoring point for the jaw muscle to attach",
". The opening was only covered by the jaw muscle, this naturally would have left a point of weakness i... |
[
"Do we know of any animals which evolved with three eyes in some arrangement?"
] | [
false
] | I was curious as it would seem to be a huge advantage having one pointed backwards, to spot predatory attacks. | [
"http://imgur.com/gallery/VDU2s45",
"Here is a picture. They look like a bearded dragon almost but no spiky beard and less horny head. Almost resembling a cross between iguana and bearded dragon imo."
] | [
"http://imgur.com/gallery/VDU2s45",
"Here is a picture. They look like a bearded dragon almost but no spiky beard and less horny head. Almost resembling a cross between iguana and bearded dragon imo."
] | [
"Other than spider and some other inverts that have multiple eyes I don't believe there is. \nI'm not sure of the actual reason but I would hazard a guess that the back of the heads space is taken up by the brain, also I think it takes a lot of computing power to put the images our eyes see into an actual picture s... |
[
"Are animal toxins related?"
] | [
false
] | null | [
"Closely related species that produce venom might produce similar toxins, for instance there are enzymes in snake venom which are common to all venemous snakes. Some distantly related animals also produce the same toxins. Check out tetrodotoxin, one of the most potent toxins, which is produced by puffer fish, worms... | [
"Yes they can be. One interesting example is a protein found in snake and mammal venom. There a proteins found across vertebrates called defensins that are used in immunity. They can directly attack bacteria by piercing their cell membranes, and are also involved in regulation of immunity. Both snakes and platypus... | [
"Medically speaking a bee, wasp, and hornet are completely different in terms of allergies. One patient can be allergic to a hornet, but multiple stings from a wasp or bee won’t trigger an allergic reaction. \nSource: had a patient come in with this. "
] |
[
"How does a pandemic like spanish flu or coronavirus end?"
] | [
false
] | null | [
"In general, epidemics end when the pathogen can no longer find enough susceptible individuals to sustain a chain of transmission. This happens when each new infection goes on to generate, on average, less than one additional infection. Containment can help with this, but mostly it happens when enough people get in... | [
"However, COVID-19 has a higher fatality rate, around the same fatality rate as the Flu (~2-3%)",
"There are problems with this statement.",
"To quote this source (note that cCFR stands for confirmed Case Fatality Rate and includes only those that have been definitively proven to have the virus): ",
"https://... | [
"It's essentially the same virus that causes SARS.",
"More accurately, it's from the same family of viruses that caused SARS but is its own thing. ",
"The COVID-19 virus is clearly a separate introduction into human populations from a still-unknown animal reservoir",
"."
] |
[
"How do plants move without muscles?"
] | [
false
] | This time lapse video shows house plants moving about. I'd like to understand the mechanisms involved here. Do the cells "cooperate"? Is it just reacting to sunlight? Video: | [
"As far as I understand it, the side away from the light grows faster, \"turning\" the plant towards the light.",
"Plants also move using cell pressure, like deflating a balloon, as you see when you touch a mimosa and it curls up. "
] | [
"It's from a phenomena called \"phototropism.\" Plants have several signaling chemicals, the primary chemical of which is called auxin, that, when touched by a light source, activates several genes which change the hormone levels in the plant. The plant doesn't technically \"move;\" it actually ",
" in the dire... | [
"Thanks for the awesome reply! "
] |
[
"Is carbon monoxide lighter than the air we typically breathe? In other words, if it is released into an attic of a residence, with it seep into the living space of the same or will it rise out through vents in the attic?"
] | [
false
] | null | [
"It is slightly less dense than air so it will primarily exit upwards. However, any high concentration will diffuse through the air to areas of lower concentration so it will definitely go down as well, though it shouldn't get trapped or pool in low areas. Any forced air currents will also greatly affect where th... | [
"Yes. The difference in weight of CO as compared to nitrogen gas, which makes up ~78% of the air you breathe is negligible. As FatSquirrels said, air currents (convection) would cause dispersion throughout a building / area. It's safe to put a CO detector near the ground."
] | [
"Yes. The difference in weight of CO as compared to nitrogen gas, which makes up ~78% of the air you breathe is negligible. As FatSquirrels said, air currents (convection) would cause dispersion throughout a building / area. It's safe to put a CO detector near the ground."
] |
[
"Why are frequencies in the Electromagnetic Spectrum visual and others audible?"
] | [
false
] | null | [
"There are no audible electromagnetic frequencies. Sound is a pressure wave, not an EM wave."
] | [
"What you're talking about is called modulation, where the wave is modified to carry information. This is easier in radio waves than light because you can control the frequency or amplitude of a radio wave using a simple circuit, whereas to modulate light you'd have to have fine control over individual atoms. Also,... | [
"Actually optical modulation for data transfer is very effective and in very wide use. Anything using ",
"IR communication",
" farther than a few centimeters uses some form of carrier wave in order to reduce signal noise. There are also ",
"visible light data transfer",
" versions.",
"I think you're assum... |
[
"In physics we learn of kinetic and static frictions. It's binary in that the object is moving or it isn't. Is it really binary or does the coefficient for kinetic friction scale with speed?"
] | [
false
] | How I think of it is: static frictions have a higher coefficient because the objects are more set and locked in. As soon as it's in motion the ridges on the objects aren't as locked and sort of bounce and skip over the ridges which is why the coefficient is lower. Much like a motorcycle going over those small bumps, th... | [
"The static/kinetic friction model is just a model. Your intuition is one of the commonly given reasons that sliding friction is almost always lower than static friction.",
"However, if you examine the model closely it is not always perfect. In particular, objects that deform easily often have a speed-dependent f... | [
"It's really complicated. A constant coefficient is a pretty good first order model. But above that, major problems are that other characteristics and forces interact, such as heat generation, wear, deformation, slip-stick, any contaminants or lubricants, and, at high enough speeds, atmospheric interaction. ",
... | [
"In addition to the other answers here, I'd just like to mention that if you're interested in how to model a speed-dependent friction system, it's a fairly common example used in most Differential Equations textbooks, so you can usually find some good breakdowns of the math involved, as well as an interesting model... |
[
"If the color we see in objects is the one that it reflects, does that mean that an object's \"real color\" is \"white minus the reflected color\"?"
] | [
false
] | Does that mean that we are really seeing the "negative color" of reality? (I'm not sure how to phrase it). | [
"Color is not a property an object has or possesses. Color is a result of how light and matter ",
"For example, a green object lit by white light absorbs everything except for green light, so we see what isn't absorbed. The object has modified the spectrum of light from the source that now hits your eye.",
"Fu... | [
"Objects are not \"colorless\". An object's \"color\" is the color it appears to our eyes. This color is caused by the object reflecting those wavelengths of light. The reflected wavelengths are the source of the color that you perceive. "
] | [
"I can see where you're coming from, although I think you're getting a bit lost in the semantics. In one sense, there are properties of a material that determine what wavelengths it reflects so it has intrinsic color. On the other hand, color is really electromagnetic radiation, so without light there can't be colo... |
[
"Guys... It sucks to admit, but I don't really understand evolution."
] | [
false
] | [deleted] | [
"It doesn't suck to admit it.",
"Stupidity isn't ",
" knowing things.",
"It's not knowing things and being content with not knowing."
] | [
"Natural selection - Think about the people you know. They have different skin colors, they are tall and short, some are smarter, some are stronger, etc. There is variation in populations. When some sort of driver causes certain members in a population to be more 'fit' - able to survive and reproduce, then the dist... | [
"Actually I think that's ignorance. The good news is that stupidity is curable via inquiry, so he's already on the road to recovery."
] |
[
"Would two marbles in space affect each other gravitationally in the same way that two planets would?"
] | [
false
] | Does gravity act only at a certain scale, or does it act on objects even at the scale of marbles? | [
"Yes, of course. It's not called Newton's law of ",
" gravitation for nowt - you pull on me, I pull on my desk, my desk pulls on the crown of the king of Sweden...",
"I like this question. :)"
] | [
"Yes."
] | [
"The only difference would be the magnitude of the numbers involved, the math doesn't care about the size of the objects."
] |
[
"Is the galaxy a mostly flat plane like it’s depicted in pictures? If so, why?"
] | [
false
] | In most artistic depictions of the Milky Way galaxy, it’s illustrated as a roughly flat 2 dimensional plane. What I was wondering is if that’s really the case, or if solar bodies revolve “above” (relative to said 2D “plane”) and “below” the center of the Milky Way? | [
"To add some numbers to the good answers here: our galaxy has some thickness to it, but it’s wider than it is thick by a factor of 10-50 depending on how you measure. Roughly the same relative thickness as a thin-crust pizza."
] | [
"The pizza example really made it click for me, thank you"
] | [
"Spiral galaxies (like ours, and Andromeda) are mostly flat at large scale. There could be some bodies moving at angles to the galactic center, but most are generally in that plane, like roller skaters at a rink all skating the same direction.",
"A body that is 'above' the plane will eventually be 'below' the pla... |
[
"Explanation of how gifs like these work"
] | [
false
] | [deleted] | [
"This is what happens: ",
"http://en.wikipedia.org/wiki/Afterimage"
] | [
"I did this but only for science. "
] | [
"I did this but only for science. "
] |
[
"During the most recent Ice Age was there a difference in the seasons from what we have now?"
] | [
false
] | I'm writing a short story based during an Ice Age (non Earth) and was wondering what the seasons were like. Now granted the world as a whole was much cooler but was there still a much warmer 'summer' period where the ice or frost might melt away before a much longer and harsher 'winter' came in? Edit: Also any good rea... | [
"I research \"Ice Age\" glaciers (aka Last Glacial Maximum, 15-20,000 years ago), and the fundamental assumption is that if the winters were a certain amount cooler and/or wetter than they are today, then the summers will have been equally cooler and/or wetter. We assume this because there are many deposits that im... | [
"Possibly! I can't say for sure, but there have to have been flowering plants around in the spring and summer, because pollen counts of certain species are a way some scientists track paleoclimate around the world. "
] | [
"Climate typically changes much more in the temperate and polar regions than in the tropics. The Ice Age tropics were probably only slightly cooler than they are now, but they were certainly much drier. The temperate zones would have had vicious winters, but summers might not have been bad at all at the southernm... |
[
"Question about General Relativity"
] | [
false
] | I'm having trouble wrapping my head around the idea that objects in freefall are in an inertial reference frame. Clearly they are experiencing a feeling of "weightlessness" just like someone in an inertial reference frame in deep space. But they are also accelerating towards (let's say for the sake of argument) the E... | [
"In the context of general relativity, they are ",
" accelerating (in the sense of an applied force) toward Earth. It's just that in the presence of a massive body spacetime is curved in such a way that an inertial reference frame is one in which the radial distance decreases as time increases. On the other hand,... | [
"The equivalence principle states that there is no local difference between being in free-fall and being in free-float. That is, put you in a box with no windows, put you in deep space or put you in free fall, and you cannot tell the difference. As soon as your box has windows you can judge your movement against st... | [
"Actually, we can test empirically that we are ",
" in an inertial reference frame. Hold some neutral object (like a pencil or piece of paper) out at arms length and let go. Does it stay there, so that if you close your hand again you'd be holding it? If not, you're not in an inertial reference frame. You know th... |
[
"Why did the lakes and oceans of Mars disappear? Will the same thing happen to Earth?"
] | [
false
] | null | [
"Why does Venus have a thick atmosphere then? It doesn't have an intrinsic magnetic field and it is closer to the sun. Yet the atmosphere is thicker than Earths."
] | [
"we have a magnetosphere that protects us and our atmosphere from the solar wind.",
"While a magnetosphere protects against solar wind sputtering, there are many other kinds of atmospheric loss, some of which only occur because a planet has a magnetosphere. ",
"Much of Earth's atmospheric loss comes as a direct... | [
"Before about 3.8 billion years ago, Mars may have had a denser atmosphere and higher surface temperatures, allowing vast amounts of liquid water on the surface, possibly including a large ocean that may have covered one-third of the planet.\nAround 3.7 to 4.2 billion years ago, the red planet’s atmosphere was the ... |
[
"If all matter emerged and spread from a singularity, how do we use telescopes to look back at the \"young universe\" — wouldn't the light from a young universe have passed by the area of space we occupy before we arrived here?"
] | [
false
] | This one is just for fun, but something that always seemed counter-intuitive to me. We often here stories of scientists using telescopes to look deeper and deeper into space, and get an actual picture of what the universe looked like when it was very young. The idea seems to be that you are looking at light that has ta... | [
"Your two questions seem to stem from the same misconception:",
"If we imagine the model of our solar system is the universe, with the Sun being the source of the singularity/big bang...",
"The big bang did not occur at a single point. ",
". You are viewing the big bang as matter moving away from one, definit... | [
"Thank you. I was just reading about recession velocity and Hubble distance to gain a better understanding of this. Very interesting. "
] | [
"You seem to have several misconceptions on what the current consensus on the Big Bang is; you should find ",
"this popular SciAm",
" article very informative. If you read it and things still don't make sense and you're left with questions, read it again. You will see that your questions stem from the same misc... |
[
"When we whisper, are we using our vocal cords at all? And if not, how can we still make out vowel sounds?"
] | [
false
] | null | [
"Vowels are distinguished primarily through different frequencies created by the shape of your oral cavity (your mouth hole). If you look at ",
"spectrograms of different vowels",
", you can see these frequencies coming through.",
"The important feature of vowels compared to consonants is not that the vowels ... | [
"Unfortunately it's not that simple. There are multiple ways in which one may be mute. If it's neurological, then chances are no, whispering isn't going to happen. If it's because there's a physiological issue with their vocal chords or related organs, then no. If you're mute because of receiving some sort of brain... | [
"Does this mean that a person who is mute can whisper words/small sentences?"
] |
[
"How does electrochemical replacement plating (in metallurgy) work exactly?"
] | [
false
] | I'm currently researching ancient Central and South American metallurgy and one of my sources is discussing a gilding technique called 'electrochemical replacement plating.' From my understanding this involves placing a copper (or similar metal) sheet in an electrolyte solution containing gold or silver. In the process... | [
"Silver hates to be chemically bonded with anything else. It likes to be pure and solid. This is also the reason why silver is always found on the ground as nuggets and not as ore. ",
"Copper also hates being chemically bonded. But Silver hates being bonded more than copper. So you have a situation where copper i... | [
"They adhere to the surface, abeit weakly. A little shake will rub off all the metal crystals. ",
"what causes them to adhere to the copper surface, rather than simply collect in the bottom of the vessel that contains the solution?",
"because the reaction happens on the metal surface, and the rough surface of ... | [
"Thank you. That makes a great deal of sense. But when the displaced silver/gold atoms precipitate from the solution, what causes them to adhere to the copper surface, rather than simply collect in the bottom of the vessel that contains the solution? Is this also an electromagnetic process?",
"(EDIT: in case you ... |
[
"Could the helium released from an MRI quench be 'caught' and re-used?"
] | [
false
] | After hearing about helium being a finite resource while studying medical imaging, I have been wondering if there is a reason the helium quenched from an MRI machine during an emergency shut down is not sent to some kind of containment and recovery system. | [
"(Edit: For a quench, probably not, but in general, )Yes! There are several universities which have built helium recovery systems to re-liquefy helium from dilution refrigerators (used for researching superconductors to make MRIs better!) as it boils off. It's not anything special in terms of technology, and hospi... | [
"That's not a docs call. I don't see a magnet provider ever allowing it and ultimately they make the call on if they will bring in equipment. I have to provide a detailed list of bend, elbows, straight runs, etc of vent duct and verify it passes a form pressure test before they bring the magnet out. The clearance f... | [
"It took two years of lurking here before something finally came up that I can comment on! I'm a couple drinks in, and the grammar/spelling nazi's on reddit are a major reason that I've never commented, but here it goes. There is a very simple system that exists to do this. I used to modify the liquefiers that ar... |
[
"Does a virus always inject itself into the same location within a chromosome?"
] | [
false
] | I was reading about the HeLa cell lines, and the book mentioned that the reason that the cells were able to divide indefinitely is that the HPV-18 virus infected a segment of the 11th chromosome that was important in suppressing tumors. That made me wonder if that particular virus always inserted itself into that regio... | [
"I haven't gone too far into detail in learning about it, but from what I gather it depends on the virus. Some may insert randomly (or may not insert into host DNA at all, just leaving their own DNA to float almost like a plasmid in the nucleus). Others have a preference to insert at certain points, others insert s... | [
"According to ",
"this publication",
" there are a couple of seemingly preferred integration sites and quite a few of them are relevant in cervical cancer. Since you are reading about HeLa characterizations in books, I assume you are a biology/medical student? in which case that paper should give you the answer... | [
"Viral integration events cluster at specific \"hotspots\" but they are a highly random event. In fact, the viral-cellular DNA junction varies so much between different cancer cells that it can be used as a unique fingerprint, such as in ",
"this paper",
".",
"In the case of HPV, there are ",
"over 1,500 kn... |
[
"How realistic is widespread nuclear energy? Does the Earth have enough uranium deposits to provide power long term?"
] | [
false
] | null | [
"I'm hoping someone with more concise data comes in to add numerical content, as I don't have a lot of my data/notes available at work.",
"From a qualitative perspective, it depends on a lot of things. One of those things is what type of nuclear reactors we use in the future. Current plants generally use about 1%... | [
"According to ",
"this",
" study, there's enough Uranium to power the world for a while.",
"There has been enough Uranium identified to produce 2.9 x 10",
" J energy, and it's estimated that global reserves actually contain enough for 2.2 x 10",
" J.",
"For reference, global energy consumption in 2010 w... | [
"There are materials (hastealloy N I think) which can withstand the corrosive environment. But there is cost involved. The main challenges are engineering/economic challenges, but one would assume we'd figure it out if we didn't have many energy choices left. There are other reactors which could utilize thorium and... |
[
"When someone loses weight, where does the mass actually go?"
] | [
false
] | Let's assume that I lost 2 lbs. this month (and that it wasn't just "water weight"). Let's also - and quite reasonably - assume that I did not set off an explosion equivalent to . Where did my mass actually go? The possible avenues I can think of are breath, sweat, urine, feces, and skin shedding. Do we have an unders... | [
"Breathed out as CO2.",
"I can go into more detail, but in short: Fats are converted into glucose, glucose is broken down into energy and CO2, which get expelled via breathing. "
] | [
"glucose is broken down into energy and CO2",
"And a fair amount of water, ",
" actually, I have no idea if you breathe out that water. On some level, all the water in your body is interchangeable, so water from respiration just becomes part of the water circulating in your blood."
] | [
"This is a common misconception. no solids are excreted into the bowel, or liquids for that matter under normal conditions. The bowel is purely for absorbing nutrients (at which it is over 90% efficient) and extracting water.",
"When you eat it goes into the stomach is mixed with acid and enzymes that break down ... |
[
"Can entropy be reversed?"
] | [
false
] | I somehow found Wikipedia's page on entropy, and then decided to try the simple English version of it found That helped me understand what entropy is. The question is, can entropy be reversed? Can the cup of tea in Wikipedia's example somehow attract heat once again? Are there people working on this sort of thing? | [
"The short answer is no. A system tending to a state with higher entropy is a statistical phenomenon.",
"Imagine a neatly organized deck of cards (by suits, then increasing value). It is at a state of minimal entropy - there is exactly ONE way that it is organized this way. If you shuffle it, it'll tend towards b... | [
"Entropy",
" ",
" be reversed locally, as is the case with the ",
" of life on Earth, which represents a local pocket of decreasing entropy within the Sun's vastly greater increasing entropy. ",
" entropy of a ",
" such as the Universe, however, cannot be reversed.",
"For the classic speculative answer,... | [
"The issue is not open/closed, it is local/equilibrium. That is, if a system is not in equilibrium then you can get local decreases in entropy."
] |
[
"What is the consistency of the brain?"
] | [
false
] | I've been told that the human brain is like custard. My friend, however, argues that it's sort of like a mushroom. Spongy, but solid. Are either of us right? | [
"Fresh brain is more like custard. Brain that's been \"fixed\" (treated with chemicals in preparation for histology) is more like a mushroom."
] | [
"the brain is mostly fat (lipid cell membrane, lipids in astrocytes, etc), so if you've ever held fresh fat in your hands you probably have a good idea of what a brain feels like. custard is actually a good description of it.",
"however, if your friend wants to be picky about it, there's an outer covering--a sack... | [
"It's mushy, kinda like jello, it will hold it's form, but won't take much abuse outside the skull."
] |
[
"if Octane has a boiling point of 125C why is gasoline so volatile?"
] | [
false
] | In my chemistry class we are learning organic compounds, saw that octane had a 125C boiling point, and was confused as I know its not the liquid that burns in gasoline. I know gas is a blend of compounds but mostly octane, so who better to ask, then you ! | [
"gasoline isnt that volatile, the vapors are. in engines, you put them under massive pressure and they combust when a spark is introduced. you can actually put a cigarette out using gas if you suck off the vapor. dont do it..."
] | [
"I don't think that octane is particularly volatile (in the scientific sense of the word - ",
"http://en.wikipedia.org/wiki/Volatility_%28chemistry%29",
") in comparison with any other liquid with a similar boiling point (like water). Its just that the that octane vapour is mixed nicely with the air and so is r... | [
"vapors"
] |
[
"Do digital maps of the universe account for movement of stars/galaxies?"
] | [
false
] | [deleted] | [
"Galaxies are hundreds of thousands of light-years across. They move at about a thousand kilometers a second at most. You could watch the sky for a hundred million years without seeing any change in their relative positions."
] | [
"Galaxies are hundreds of thousands of light-years across. They move at about a thousand kilometers a second at most. You could watch the sky for a hundred million years without seeing any change in their relative positions."
] | [
"Based on what we observe."
] |
[
"What would the advent of quantum computing mean for cryptography?"
] | [
false
] | [deleted] | [
"Researchers are also developing new classical cryptography schemes that are not based on factoring large primes, hence robust against Shor's algorithm."
] | [
"Well they aren't tailor made to factor large numbers, but probably the most famous quantum algorithm (Shor's algorithm) does just that. So yes, it would mean that the RSA encryption scheme would be breakable. Still though, it might be longer than 10-15 years before we have a quantum computer large enough to break ... | [
"Note: RSS is \"really simple syndication\", and is a web protocol.",
"RSA is the famous public key algorithm. "
] |
[
"Could there be moons orbiting gas giants in very low altitudes barely enough not to fall into their planet?"
] | [
false
] | ...like between the thick gas clouds, the patterns on both Saturn Jupiter's surfaces inspired me to ask this! | [
"If they were inside the atmosphere of the planet the friction would make them spiral into the core of the planet. "
] | [
"That point at which gravitational forces pull a moon or body apart is called the Roche limit, I think."
] | [
"On top of CaptOblivious' comment about how there would be atmospheric drag, there's also a tidal effect. For a moon orbiting around Jupiter, for example, the gravitational tug from Jupiter on the side of the moon facing the planet is a little bit stronger than on the far side. The closer the moon is, the greater t... |
[
"If an Astronaut were to die in space from natural or accidental causes, what would the procedure be?"
] | [
false
] | null | [
"The simple answer is that no-one really knows. There's no precedent for this, whose jurisdiction it would fall under.",
"Likely it would depend where it happened - on which specific section on the ISS, on which launch vehicle for whose responsibility it would be. Probably though, whoever was running the crew rec... | [
"Here is the speech",
" Nixon was going to give in the event the Apollo 11 crew died or became stranded on the moon. The plan was to just leave them. You might find it interesting that burial arrangements for the crew were planned to be the same as those lost at sea, their bodies being commended to \"the deepest ... | [
"ISS Commander Chris Hadley's book \"An Astronaut's Guide to Life on Earth\" goes into a bit of detail about astronaut death.",
"Basically, if an astronaut dies during EVA, there isn't much that can be done, since EVAs take months of prep time and unplanned ones are quite risky in even the best circumstances. If ... |
[
"How do newborns get full length telomeres?"
] | [
false
] | If as we age we get shorter and shorter telomeres due to replication, how do newborns get full length ones? And if the mechanism is available, why isn't it used in the rest of the body? | [
"The enzyme telomerase can lengthen telomeres, however it is only active in small portion of cells (including gametes, hence why children newborns don't have short telomeres). Uncontrolled expression of the telomerase gene is believe to underlie the \"immortality\" of cancer - probably a good reason for the body no... | [
"Makes sense O.O Thanks!"
] | [
"It's also expressed in embryonic stem cells."
] |
[
"How small can a living being be while still maintaining at least a human-level intelligence?"
] | [
false
] | null | [
"We can't answer such hypothetical questions about aliens objectively."
] | [
"I'm not asking about \"aliens\", it's just an example.... \nIf I can make the question simpler, how small could a human/earth living organism can get while maintaining a level of intelligence high enough to say, hold a conversation with another human being?"
] | [
"There are no organisms other than humans that have language that we know of. The shortest known human that grew to be old enough to talk was 21.5 in. tall. Could they have been smaller? possibly. It's not clear how to objectively determine what a lower bound would be. Enough to fit a head and organs (of whatever s... |
[
"What causes eye redness when I wake up in the mornings?"
] | [
false
] | null | [
"You most likely sleep with your eyes partially open. The environment in your room is ",
" harsher for your eyes than the environment experienced when you have your eye lids closed since it is much drier and has more foreign bodies (i.e. dust). This harsher environment dries out and irritates your eyes causing th... | [
"You will actively and passively blink more."
] | [
"Why would sleeping with my eyes partially open cause redness while having my eyes open during the day does not?"
] |
[
"Why do people vomit after intense exercise?"
] | [
false
] | People puke when they push themselves farther than they can go but why. Is it to decrease their stomach capacity so there is more room for the lungs to fill with air? But guesses are bad so go science! | [
"Based on clinical studies, overeating/overhydration prior to strenuous exercise is a top causal link to exercise-induced nausea. - ",
"Source",
"List of all four studies on the topic"
] | [
"I'd like to add that the major cause of over hydration is the misconception on how much water you should intake in a day.",
"It is normally reported you require 8 glasses of water a day. That is incorrect misconception that started in the 1960s due to a study released saying the average person required about 1.8... | [
"It has been linked to endorphins released while exercising, endorphins sometimes cause vomiting. Eating or drinking too close in proximity also can lead to vomiting. Finally lack of proper breathing can cause it like holding ones breath and sticking out your tongue can lead to gagging."
] |
[
"What laws of physics govern this specific effect?"
] | [
false
] | I'm completely baffled to explain how this works. My only guess is that the thing "floating" is super cooled ferret magnet or something similar. Could you please tell me what is happening here? Thanks in advance. | [
"ferret magnet",
"I chuckled a little bit :) It's \"ferro\" magnet what you mean. Ferro is italian (?) for iron. Now to the real question.",
"What you see is ",
"Flux Pinning",
". Essentially, you trap magnetic lines in a superconductor. Changing the position of the superconductor requires much more force t... | [
"I apologise for the mistake, in my language it's called 'magnes ferrytyczny' so i just translated it in my head, now I see that ferret is actually an animal :)",
"Thanks for the explanation!",
"edit: just checked, ferrum is latin for iron, thus Fe :)"
] | [
"It's called the Meissner effect. Basically, in a superconducting material, if magnetic fields penetrate the material (which happens in some superconductors but not other) then the magnetic field lines become...sort of squeezed into tubes, and it becomes difficult to move the tubes with respect to the magnet. This ... |
[
"Parade of low-earth-orbit satellites?"
] | [
false
] | About an hour after sunset, my son and I just saw about 30 lights moving across the sky that looked exactly like LEO satellites (we’ve watched the ISS pass over before, so we know what to look for). These were not airplanes. What was notable was the sheer number — about 30 in groups of 3-5 over about 12 minutes — but ... | [
"You've most likely seen the Starlink satellites being deployed by SpaceX. Their goal is to deploy a large set of satellites (up to 12,000) to provide broadband internet access around the world.",
"These satellites are being deployed in batches by the SpaceX Falcon 9 rocket. The Falcon 9 carries the satellites in... | [
"I believe they also intend to make future Starlink satellites less noticeable by reducing their albedo (how much light they reflect) so it might be worth trying to see them while you can."
] | [
"While it is true that they continue to launch satellites, it is false to claim that they have taken no concrete action to reduce albedo. From the ",
"Starlink-2 launch presskit",
":",
"\"On this flight, SpaceX is also testing an experimental darkening treatment on one satellite to further reduce the albedo o... |
[
"Why is it so hard to artificially replicate so many naturally occurring substances?"
] | [
false
] | null | [
"A good place for this question is ",
"/r/AskScienceDiscussion",
"."
] | [
"I'm not familiar with that sub, quick elaboration?"
] | [
"It's a sister subreddit of ",
"/r/AskScience",
" that the mods run. Good for open ended questions."
] |
[
"Although there is a firm understanding of the pathology of cancer, why has it been so difficult to find a direct cure?"
] | [
false
] | null | [
"It’s because ‘cancer’ as a catch-all term is misleading. Cancer is just a disruption of the regulation of the cell cycle, resulting in unchecked cell division and growth. There are many different types of cancer arising from many different types of tissues and caused by many different types of aberrations of the c... | [
"To be honest I couldn’t really tell you. It’s out of my area of expertise. Sorry."
] | [
"If I’m not mistaken this is why hair loss happens during chemotherapy, the cells responsible for hair growth are also fast growing, and are thus also susceptible."
] |
[
"What are the chances that there exists a solar system identical to our own?"
] | [
false
] | By identical, I don't necessarily mean all objects have the same mass and size, I'm speaking a little more generally than that. I'm talking about same type of star, same placement of eight planets and asteroid belts; same number of jovian planets. I'm not necessarily asking for a number, but are the percentages of ther... | [
"I'll just leave this here...",
"http://dictionary.reference.com/browse/identical"
] | [
"Identical twins aren't \"identical\" in every possible way. So to call them identical is incorrect? ",
"Could you say that all hydrogen atoms are identical? If the electrons aren't in the same place at the same time, would they still be considered identical? It kinda all breaks down to semantics at some point, n... | [
"Be careful not to let big numbers bully you. 100B planets is a lot, but OP's amended requirements for \"identical\" are still pretty strong, and there are a ",
" of ways a solar system could be put together just from a combinatorial perspective. Hopefully we can get someone in here with expertise in solar system... |
[
"If a cloned organ starts off as \"old\" as the original cells used for the cloning and with the same accumulated damage to the DNA and shortened telomeres, then shouldn't we be preserving our DNA as soon as possible?"
] | [
false
] | Wouldn't that ensure the "youngest" possible cloned organs for ourselves when the technology becomes viable in the future to extend our lives in such ways? In other words, let's say I am in my 20's now, wouldn't I want to preserve my DNA as soon as possible so that if the technology to clone your own organs becomes via... | [
"Theoretically that would be ideal as your DNA will have accumulated less mutations. A mutation in a part of the genome that a tissue doesn't use has no effect but try using that DNA to recreate another tissue, you might run into a problem",
"Couple options would be to preserve when younger. Another would be to t... | [
"Although you're right, our telomeres do shorten time and lead to aging/senescence, we do have the natural ability/enzyme to lengthen our telomeres (telomerase), we just don't express it most of the time. In fact, one common step of a cell becoming cancerous is expressing higher levels of telomerase to overcome the... | [
"This is how we immortalize most cell lines for research, by the addition of hTERT. Other times a virus such as SV40 is used, but the \"cleaner\" way is with telomerase. ",
"I wouldn't want that in my body though. It's highly unpredictable not just how a pure cell culture will respond, but to then add the complex... |
[
"Do solar systems have a theoretical size limit?"
] | [
false
] | If not do they have a realistic size limit? | [
"If you mean by the space in which objects would be gravitationally bound to a star then there are some factors you need to take into account. The theoretical maximum mass of a star is around 150 solar masses (one solar mass is the mass of our own Sun). So for a single star solar system it would be the volume of ... | [
"I would think at some point it would collapse to a black hole, maybe total of 450 SMs based on a Trinary system?"
] | [
"The mass of the black hole that forms when a large star runs out of fuel in its core will not simply be equal to the mass of the star. The majority of the star's mass will be blown outward in the supernova explosion, and only the core material will collapse into a black hole. So even if you have a triple system ... |
[
"How good of a conductor is our brain?"
] | [
false
] | no idea if this should be tagged physics or human body,sorry in advance. I was just wondering,since our brain sends electric signals,how much of them is lost along the way? | [
"First, some background; ",
"The question itself is a little difficult to address because the way we define conductivity for metals and conductivity for neural tissue is very different. For physical, rather than biological, systems, we employ what's known as Ohm's Law to determine conductivity. Ohm's Law states t... | [
"That's not how neural signaling works. ",
"As a signal travels down a neuron, none of it is lost due to resistance, because at every step along the way the neuron uses energy (derived from the ion gradient across the membrane, which is derived from ATP) to boost the signal to full strength. So it doesn't matter ... | [
"I have a degree in physics and a background in biomedical sciences. Maybe my response fills in what you're looking for? ",
"Though your response is definitely great! "
] |
[
"Proton-proton reacton - why the \"detour\" via He-3"
] | [
false
] | [deleted] | [
"There's a lot of excess energy in that reaction: the mass of two deuterons is 23.8 MeV higher than the mass of a He-4, which is enormous. It has to go somewhere.",
"If the deuterons had the right energy to hit a resonance, you could make an excited He-4. It's even possible that the energy could be released as on... | [
"Quoting Donald Clayton's \"Principles of Stellar Evolution and Nucleosynthesis\":",
"One could imagine that He",
" might be produced by the reaction D + D → He",
" + γ. This reaction, however, suffers from a small cross section and, more importantly, from the fact that ",
"He then describes the chain in t... | [
"Pretty much, at least in stars that are still in the hydrogen burning phase (which is all stars most or all of the time).",
"Sometimes fusing with a proton isn't a viable reaction, though. That's why Clayton brings up the H + He",
" → Li",
" reaction: having 3 protons with just 1 neutron in a nucleus is so... |
[
"Geologists: If the existing continents were once part of a supercontinent called Pangea, do we know that there weren't additional continents elsewhere on the Earth that were swallowed up at the receding ends of the continental plates?"
] | [
false
] | My limited understanding of plate tectonics is that magma is expelled from one end of the plates, and rocks are gobbled up at the other end, like an epic treadmill. I also heard that some plates might "spin", and thus the rocks on those continents might be much older. I just wondered if we had a clear idea if there was... | [
"There are two kinds of crust:",
"-",
"Continental Crust",
" is very thick and light, composed primarily of felsic igneous rocks.",
"-",
"Oceanic Crust",
" is thin and dense, composed of mafic igneous rocks, which are enriched in heavier metal elements.",
"When a tectonic plate made of oceanic crust c... | [
"To a first order this is correct. It is however important to point out that continental crust is not completely permanent. Some of the sediments deposited along the margins of convergent boundaries (which were originally produced by erosion of the continent and transport by rivers to the oceans) will be entrained ... | [
"The plates do not stop moving immediately, but there is typically a slow down in the velocities of the plates when true continent-continent collision starts. The timing of the slow down in plate velocities is sometimes actually used to bracket when collision started as rocks within the collision tend to get a bit ... |
[
"Why are Airforce employees wearing Level A Hazmat suits when inspecting the X-37B space plane?"
] | [
false
] | [deleted] | [
"Rocket fuels can be really toxic. ",
"edit to add link: ",
"http://www.msnbc.msn.com/id/6817699/ns/technology_and_science-space/"
] | [
"The X-37B's rocket motor uses hydrazine as a monopropellant: ",
"http://en.wikipedia.org/wiki/Hydrazine",
"A quote from the EPA via the above link:",
"Symptoms of acute (short-term) exposure to high levels of hydrazine may include irritation of the eyes, nose, and throat, dizziness, headache, nausea, pulmona... | [
"I think it's done initially to make sure nothing hazardous from the engine leaked or remains. One of the pictures notes \"A crew of vehicle handlers clad in suits to protect against hazardous materials (like any remaining rocket fuel)\"",
"I'm sure they will scrub it down in a clean environment before launching... |
[
"I've heard that the longer males hold in urine, the more risk they take in getting prostate cancer. Is there any basis in fact, or is this an old wives' tale?"
] | [
false
] | My entire life growing up I've heard this but I don't know if it's true. Can the smart people of reddit help confirm or deny? | [
"Not according to ",
"the American Cancer Society",
". Uptodate lists the following as risk factors for prostate cancer: age, ethnicity (more common in black men), genetics (commonly 8p deletion, also BRCA), infectious factors (XMRV exposure, trichomonas infections), diet (high fat, low vegetables), diabetes (... | [
"I'm not aware of any scientific studies involving voluntary urinary retention as a mechanism for anything.",
"Voluntary urinary retention is certainly a mechanism for UTI, however you are correct that in general there are few known other effects. I believe there have also been studies done on voluntary urinary ... | [
"What if when you hold the foreskin over the head of your penis and then urinate a little so it fills up with piss, and then release it? are you damaging the head or your penis in any way by doing this?",
"Edit: Why are you all downvoting a perfectly legitimate question? this isn't a joke."
] |
[
"What is the actual mechanism by which the body generates a fever?"
] | [
false
] | To my very dumbed down knowledge, the hypothalamus pulls some regulatory stuff to get pyrogens like IL-1 to circulate in the body which somehow adjusts the body's "thermostat" to default to a higher temperature. My question is, how does this actually generate a fever? Where is the increased heat/thermal energy actually... | [
"You are right, it is surprisingly difficulty to find the type of information you are asking about when you include the word \"fever\" in your search.",
"",
"Our body heat is regulated by our body's ability to balance of how much heat we generate and how much heat we lose to the environment. ",
"Here are so... | [
"You forgot an important mechanic - perceived body temperature. People with serious fevers often feel cold and actively take steps to warm up (e.g. warmer clothes)."
] | [
"That's part of resetting the internal thermostat, so I didn't include it as one of the biochemical mechanisms for generating the heat, but its a good point."
] |
[
"Do wolves panic during thunderstorms the way domesticated dogs sometimes do?"
] | [
false
] | null | [
"This answer makes no sense at all. How would being outside 100% of the time matter? Thunderstorm are no more or less likely to occur over them as they are a domesticated dog. And unless you're raising the dog in a sound proof bunker (which you aren't), a dog pup is as likely to hear thunder as a wolf pup. "
] | [
"Dogs panicking during thunderstorms only primarily happens because they aren’t conditioned to the sound before formative development in the brain stops. Dog trainers can suggest playing different sounds—cars honking, trains, thunderstorms, alarms, etc.—while puppies are young so they get used to the sounds and don... | [
"Your question is stated in a way which makes it a bit hard to answer correctly. There is most likely a wolf somewhere in the world which panics during thunderstorms. But that is not very helpful. What I think you want to ask is \"Is it common for wild wolves to panic during thunderstorms?\" We restrict it to wild ... |
[
"How do we know the basics of mathematics are true?"
] | [
false
] | How do we know that 2+2=4? The times tables, square roots, formulas of area, velocity, volume, and the other basics of mathematics are true? How do we know that they are not wrong, and what would happen if some of this was wrong? | [
"If you want to see just how deep the axioms of formal mathematics go, I refer you to the ",
"Proof Explorer",
". On that site, there are a number of proofs that have been completely reduced to their most fundamental assumptions. For example, the proof that 2+2=4, for example, is 150 layers deep. There are a... | [
"The thing about mathematical truths is that they're true by definition or by construction. Mathematics works by starting out assuming certain things, called axioms, are true, and then everything else is of the form \"assuming those are true, ...\"."
] | [
"There were no axioms when the first man counted.",
"Perhaps not, but trial and error isn't really an essential part mathematics at any level. 2+2=4 is not the result of empirical observation, but rather by definition of what we mean by \"2\", \"4\", \"+\", and \"=\". It's not that we observe that two and two hap... |
[
"What do we actually know about the Big Bang?"
] | [
false
] | [deleted] | [
"\"Big bang\" can mean several things.\nFor a cosmologist, it's a theoretical framework which claims that the Universe was hotter and denser in the past. If you push the predictions to the edge, they predict a singularity. We don't know anything about this singularity because we know our laws of physics fail before... | [
"You don't need to explain the big bang to refuse some theistic consideration. The big bang is a model that describes the evolution of the universe and explains a set of observed data, such as:",
"the universe is expanding",
"at very large scales, the universe is very homogeneous and isotropic",
"we observe h... | [
"Good point, what the xian is really getting at is the \"god of the gaps\" argument. Point out to them how silly that is. For example 300 years ago, every lightning bolt and every illness was \"goddidit\", now we understand those things, so now the big bang is \"goddidit\". It's pretty ludicrous to hang your belief... |
[
"Why can't we cure virus infections? Will we ever be able to?"
] | [
false
] | First, apologies if this is an obvious question. I tried to look into this and didn't understand as well as I would like. From what I can see, one of the major issues is how fast viruses evolve, which makes it very difficult for our body's immune system to keep up and for us to create an effective treatment / cure. My ... | [
"Don't think it's an obvious question at all! Viruses are tricky little bastards for a few reasons. As you say, they evolve very quickly. Let's take flu as it's a virus we know a lot, if not the most, about. The influenza virus enters your cells by binding to sialic acid on your cell membrane. This is enabled by ha... | [
"A major issue is finding good targets for a drug. Viruses are fundamentally much less “complicated” than bacteria are. A bacterium must be able to all things necessary for life: copy, transcribe, and translate its genome, carry out metabolism, etc etc. While these activities parallel what happens in human cells, t... | [
"I think this is the best answer so far and really strikes at the heart of the difference between viruses and bacteria and why viruses are hard(er) to \"cure,\" so I wanted to expand on it a bit. If anyone wants to help me format it better somehow, please do.",
"Bacteria are ",
" They have ",
" that can be ... |
[
"How does cancer spread?"
] | [
false
] | I know it's such a simple question, but to me it doesn't make much sense. From what I know we all have cells which are cancerous that just need to be triggered to become active. Does this mean that when a cancerous cell is active, it has a chance to remotely trigger another one in another part of the body? | [
"If the cancer starts with a primary tumor (few cases of cancer do not), then the following ",
"page",
" has a decent diagram. Essentially, cancer cells in the tumor undergo further changes that allow them to get into the blood (and sometimes lymph) and eventually extravasate into another tissue. So, for exa... | [
"Does this mean that when a cancerous cell is active, it has a chance to remotely trigger another one in another part of the body?",
"No. A cancer cell doesn't trigger a non-cancer cell. Cancer cells just grow like weeds.",
"Just for ease of communication, when I way \"grow\" I mean \"grow by dividing and makin... | [
"Cancer basically spreads through 3 mechanisms. All of these usually require new mutations. It can spread through the blood, the lymphatics, or through peritoneal spread. The mutations it acquires help it survive in the new environment."
] |
[
"Could external source of neutrons be used to speed up a radioactive decay of uranium containing lava in Chernobyl NPP?"
] | [
false
] | At the end of the November 2016 the New Safe Confinement was moved into place over the destroyed reactor. However most of the fuel is still left on the site in form of lava with slow rates of natural decay. Could it be sped up by using some source of neutrons? | [
"In general neutrons can be used to transmute nuclear waste, but nobody does it on an industrial scale and it wouldn't be cheap, so you would only do it for the nasty isotopes and not for uranium. Much could be gained already by separating the different elements in nuclear waste and bury the harmless ones and store... | [
"Another thing to note, at least in the use that the OP is suggesting, is that you'd end up with a bunch of new transmuted crap in anything inert depending on the intensity and energy of your neutron radiation. It doesn't help much if you make the elephants foot less radioactive but everything else more radioactive... | [
"Not exactly harmless. You wouldn't want to make projectiles out of it and pollute war zones with a highly concentrated alpha emitter for example.",
"It would be a hole that has to be guarded (it's a poor man's dirty bomb material...). But you would not have to manage decay heat or pay very close attention to lea... |
[
"How do you design a drug and not know how it works?"
] | [
false
] | Every now and then I see a new drug that's been created to blunt the effects of some symptom, or perhaps even cure a problem, and upon further reading I'll learn that the makers, "don't know how the drug works." Take , for example. It's an ADHD drug. The makers say, "It is not known exactly how INTUNIV works in ADHD.... | [
"The human body is very, very, very complex. ",
"Its relatively easy to create a compound and see what it does in a laboratory setting. Based on lab test they can get an idea of what it might do in people, they can do this because they know the structures of existing compounds and how they interact with the body.... | [
"One way to do drug development is to use a model of the disease to determine efficacy (cell culture or animal model). Then, you screen many compounds in your model to find a new drug efficacious against the disease process. Finally, you optimize it and refine pharmacokinetics. Later, you move it into humans.",
... | [
"Maybe sometimes by accident? Zyban anti smoking medicine (it takes the joy out of smoking) was originally sold as Wellbutrin for treating depression."
] |
[
"Is the soil underneath cities nutrient rich, poor or normal?"
] | [
false
] | I was just thinking the other day about the soil underneath cities. A lot of cities have trees and plants growing in the ground and it occurred to me that cities completely stop the natural cycle of dead things decomposing in the ground replenishing nutrients. On the other hand, they don't have much growing there, so t... | [
"Nutrients are really only applicable to topsoil (the dark layer of soil ranging in depth from inches to a few feet). The foundation of any building or even a road will be deeper than the topsoil layer so the question is mostly moot."
] | [
"There is topsoil contained to the greenspace where the tree/plant/lawn is growing. It's not \"under the city\" though but just under the greenspace within the city."
] | [
"When doing construction all topsoil is removed because it makes for a terrible foundation. If trees were preserved then their original soil was preserved. If new trees were planted then they were planted using fertilizer and soil from somewhere else. "
] |
[
"What speed is the universe expanding at, and how can we measure it?"
] | [
false
] | I feel like everything I have ever read on this subject has different opinions, what is the currently accepted answer for the speed of the expansion of the universe? Or is it still under debate? | [
"The expansion of the universe follows ",
"Hubble's Law",
", which essentially states that objects recede from each other at a rate proportional to the distance between them. So objects in the universe aren't all moving away from each other at the same speed- very distant objects are moving away from us much fa... | [
"I have no idea what you mean by \"models of expansion\" here, since Hubble's law is basically an empirical observational law- i.e., redshift is observed corresponding to a velocity proportional to distance for basically all objects in the observable universe. It's similar to hooke's law (or even Moore's law) in t... | [
"Redshift certainly does give us a good idea of what's going on locally (roughly the observable universe), I didn't mean to suggest that wasn't well accepted. You're right that this is pretty much a descriptive, not explanatory phenomenon that is mostly model-independent, insofar as these things can be.",
"But m... |
[
"What theory best describes the known Universe?"
] | [
false
] | What theory is generally accepted most in the scientific community for explaining how the universe began and other mysteries like dark matter and dark energy. Please explain in layman terms or share a link to the theory. | [
"The Lambda-CDM model."
] | [
"Astrophysics dude here.",
"The intro to the big bang theory describes things succinctly, yet accurately",
"Our whole universe was in a hot, dense state, then nearly 14 billion years ago expansion started...",
"Basically, about 14 billion years ago, our universe was very small and very hot. Over time it natur... | [
"Thanks! I don't see why I wouldn't search \"standard model\" first because I have heard that term many times."
] |
[
"Has anyone proved how many colors you would need if you had a cube with an arbitrary number of three-dimensional regions in it so that no two bordering regions are the same color? It would be like the four color theorem but in three dimensions."
] | [
false
] | null | [
"There are generalizations of the 4-color theorem to arbitrary surfaces. The classical 4-color theorem is concerned with maps drawn on a plane, but we can consider maps drawn on a sphere, or a torus, or a Mobius band, or any 2-dimensional manifold. It turns out that answer to that question is known, and the maximum... | [
"Is there any deeper reason why this question is interesting in 2D but not in 3D?",
"What if the regions must be convex?"
] | [
"First, you have to understand that it's basically a graph theory question : regions become vertices of your graph, and two vertices are joint by an edge if the corresponding regions touch. ",
"The graphs that arise when you look at planar maps are called planar graphs. These are the graphs that you can draw on a... |
[
"Has all the infrastructure built for mining bitcoin whose price has since collapsed led to a glut of cloud computing power and a drop in price for other uses?"
] | [
false
] | I apologise if this is the wrong sub. This is an interdisciplinary question so I'm not sure where to ask. | [
"No. The Bitcoin mining rigs are not general-purpose computers, they are special-purpose circuits to compute SHA-hashes, and there is no real use for them except for cryptocurrency mining.",
"Things might be a bit different for Ethereum: there the price is also going down, but the Ethereum proof-of-work function ... | [
"This is incorrect. Bitcoin is NOT mined using GPUs and hasn’t been for 6 years at least. ",
"Bitcoin miners use specialized ASICs to mine.",
"Ethereum, monero and others are mined with GPUs. Not bitcoin."
] | [
"This is incorrect. Bitcoin is NOT mined using GPUs and hasn’t been for 6 years at least. ",
"Bitcoin miners use specialized ASICs to mine.",
"Ethereum, monero and others are mined with GPUs. Not bitcoin."
] |
[
"What is the approximate percentage of the world population descended from Genghis Khan?"
] | [
false
] | [deleted] | [
"I can't find it but I came across an article that said .05%."
] | [
"The article I posted says .5% of all people have nearly identical Y chromosomes "
] | [
"everything I looked up says you are right at .5%. 60% population of the world live in asia."
] |
[
"How do painkillers work?"
] | [
false
] | null | [
"Mechanism: Block COX enzymes which inhibit prostaglandin production. One of the prostaglandins (PGE2) is associated with pain and fever. ",
"Side Effects: Because we don’t have a specific PGE2 blocker, other helpful prostaglandins are also inhibited. Use of NSAIDs over a prolonged time can lead to gastrointestin... | [
"I'm not qualified to speak of most of this list, but I'll go a little more in depth about what I feel like I can",
"The short version of how neurons works is that they need to be \"depolarized\" before they can fire. In other words, neurons are negatively charged when they're at rest, but when they're made posit... | [
"There are a few mechanisms of action for painkillers, depending on the class of painkiller.",
"Opiates block opioid receptors in the pain pathways in the nervous system at the synapses. This stops the signals going from the injury to the brain to be processed.",
"Local anaesthetics, like lidocaine, work simila... |
[
"Is there an analogue to the color wheel for taste/smells? Something that covers pretty much all the bases in a concise model?"
] | [
false
] | null | [
"There has been some attempt at creating a color wheel for smells, such as ",
"this one",
", but these \"fragrance wheels\" don't even come close to covering all scents.",
"Creating such a wheel is rather difficult as humans have \"hundreds of different olfactory sensors\" capable of distinguish \"trillions\"... | [
"Would you say smell is closer to sound than color?"
] | [
"I am not expert but I have to disagree with miffedmouse that says a smell wheel doenst exist. The sense of smell is connected to our sense of taste, the tongue and the nose are interrelated. Thus it would make sense that we can break down smells into components and form a wheel because that is what we have done ... |
[
"How can baryons consisting of the same type of quarks have different masses?"
] | [
false
] | I just learnd that there are baryons which consist of the same quarks, like neutrons and Δ , but have different masses. Where does this additional mass come from? | [
"The same reason why Hydrogen has multiple energy levels in spite of the different energy states corresponding to the same two particles (a bound proton and electron). The wavefunction of the same three bound quarks can take on multiple excited configurations - the lowest energy for uud is the proton, the next high... | [
"Yes, gluons should contribute to the spin. I should note that the linked Wikipedia cites sources with conflicting results regarding how much different effects contribute, so I will defer to any experts here who can comment on the current status of this problem."
] | [
"I'm not an expert in this subject matter but I have explored the proton spin crisis out of a lay interest and my understanding is that there are actually a multitude of experiments now all designed to test this specific question (how much does each type of parton contribute to the proton's spin) and many of the fi... |
[
"How can you electrolyse water if it’s a covalent compound even though electrolysis only works on ionic compounds?"
] | [
false
] | null | [
"Electrolysis does work on covalent compounds and water is an example. ",
"Confusion usually stems from the fact that electrolysis is typically undertaken in ionic solutions (aqueous or ionic liquids etc.) or on molten ionic compounds because Electrolysis requires mobile charges in the electrolyte. But you can us... | [
"Electrolysis does happen for pure water. It's just that it proceeds very slowly due to a build up of opposite charges at each electrode. ",
"For example, at the cathode H+ is consumed leaving an enrichment of OH- ions in the solution. Any other H+ ions within the vicinity of the cathode will react with the exces... | [
"My understanding is that electrolysis of water really only happens when there is an electrolyte such as table salt or calcium chloride present. Is that correct?"
] |
[
"Is your belly button connected to anything on the inside? And if so, will it be \"anchored\" in the same spot if you gain weight?"
] | [
false
] | Is the belly button connected on the inside? What is it connected to? If it is connected by some sort of tube or string, will it restrict the distance the belly button can move outward causing a deep belly button cavity if a lot of belly fat is gained? | [
"it's connected/anchored to your bladder by a piece of fibrous connective tissue called the urachus, or median umbilicial ligament. It's basically just a left-over from the interior part of your umbilical cord.",
"When a person puts on weight such that their belly grows larger, fat accumulates in the abdominal ca... | [
"The uterus is located behind the bladder, expansion of the uterus pushes the bladder forward and thus making your belly button more shallow."
] | [
"Why does the belly button become more and more shallow during a pregnancy? "
] |
[
"Is there such a thing as a gamma radiation mirror?"
] | [
false
] | Is there any material capable of forming a surface that is not just opaque or translucent to gamma radiation, but capable of specular reflection, even of perpendicular radiation? How high can the reflectivity get? EDIT: Can't find reflection per se, but I found something about refraction. It looks like Scientists at Lu... | [
"The general idea of wave behavior is that waves reflect when obstructions are repeated and have a gap range smaller than the wavelength (so the wave \"sees\" the series of objects as if they are a solid wall). When wavelengths get down into the range of the gap size, diffraction occurs. When gap sizes are way big... | [
"You would have to get into subatomic matter and such materials do not cluster in large enough masses to create an important obstruction.",
"I suppose ",
"Neutron Stars",
" might reflect Gamma then? Though the point would be moot unless one could direct enough gamma towards the surface of one that the reflect... | [
"On the geologists front, I wholeheartedly agree. My personal favorite is Nick Zentner of Central Washington University, ",
"whose lectures on YouTube",
" are extremely lucid and clear about how geologists arrived at their conclusions and what's still up for debate. ",
"Still mindblowing to me that plate tect... |
[
"Question about SI units"
] | [
false
] | null | [
"Yes",
"."
] | [
"The gram was defined via water originally.",
"The Kelvin scale is a shifted Celsius scale and the celsius scale is also based on water (0 freezing, 100 boiling).",
"However, the meter, second, Ampere, mole and candela have nothing to do with water :-)",
"Most of that info can also be found on the wiki site\n... | [
"From wikipedia page \"History of the metric system\" : ",
"\"The metric system was, in the words of philosopher and mathematician Condorcet, \"for all people for all time\". The unit of length, the metre, was based on the dimensions of the earth, and the unit of mass, the kilogram, was based on the mass of water... |
[
"Energy of a photon of red (or blue) shifted light"
] | [
false
] | Hi Ask Science, I've been puzzling over this one for a while. Hubble observed that the light, or more specifically the absorption spectra, from distant galaxies appears red shifted. According to the theory of relativity, this means these distant galaxies must be receding from us at great speed. This leads to the theo... | [
"Energy is relative, at least kind of.",
"Think about a simple example: You are the observer (with a mass m) and observe two masses (mass m) going in opposite directions. Each carries kinetic energy of 1/2mv",
" making a total of mv",
"Now switch the reference system to one of the masses (without relativistic... | [
"I know this seems incredulous, but it is the case. In a non-time invariant system conservation of energy does not hold. Does this mean the conservation of energy is useless? Not in the slightest. Our entire local galaxy group is gravitationally bound and not undergoing expansion with respect to us, thus conservati... | [
"The conservation of energy only holds for closed systems, and the expansion of space sort of breaks that constraint. Simply, conservation of energy does not work on cosmological scales. There are some effects that decrease the total energy of the universe (like photons red-shifting) and there are some effects that... |
[
"Is there any way to prevent mass extinction after a meteor impact?"
] | [
false
] | I'm just thinking after a massive meteor impact, most plants and animals on Earth would probably die as a result of the dust blocking out sunlight. Could we quickly build thousands of air cleaners or sky-scraper sized vacuums to remove the dust from the air? Is there really anything we could do to prevent mass extinc... | [
"The dust would go to a stratosphere, up to 50 km high, so it is highly unrealistic to get rid of it with the current technology and capabilities."
] | [
"Scientifically minded people, is there no chance that a sufficiently advanced underground facility could house enough people to ensure survival of the human race, provided that it was built far in advance?"
] | [
"That makes sense I guess I didn't think of it going up quite that high. ",
"Edit: One thing I did find interesting is that there is lots of information on our capabilities to perform ",
"stratospheric geoengineering",
". It seems like if we can get to that altitude to inject sulfate aerosol, there could pl... |
[
"Do animals feel fear the same way humans do?"
] | [
false
] | And if so, to what extent? | [
"You'd be a shoe in for a Nobel prize if you could definitively prove they do or don't. The biggest problem with questions like 'can animals feel X' is that we can't communicate with them. We can expose them to stimuli that humans consider frightening, and observe their behavioral responses and/or brain activity. W... | [
"As has been pointed out, it's impossible to know. However, we CAN say that there exists great similarity between the fear responses of humans and other animals (mammals, mainly). The types of stimuli / situations that evoke fear are similar, the social reactions that fear produces in other animals of the same sp... | [
"humans are animals as well, and I am sure we (animals) all feel fear in much the same way. There seems to be a good agreement with animals as to the appropriate responses a fear input. (flight or fight).",
"How do you gauge extent? we all (animals) seem to do about the same things when we experience fear, we cry... |
[
"Is a \"complicated\" orbit the same thing as a \"chaotic\" orbit?"
] | [
false
] | I recently saw a commenter on an article about Pluto/Charon's moons say that there's a difference between a "complicated" and "chaotic" orbit. Am I right to assume that orbit of sufficient complexity, such as one involving three bodies, with two of roughly equal mass, is "chaotic" in the scientific sense (extreme depen... | [
"Is there such a thing as a \"complex\" orbit that is relatively stable?",
"The word \"relatively\" is important here, allowing me to provide an affirmative answer.",
"An example of relatively stable orbits that differ a bit from the classical ellipse are ",
"horseshoe orbits",
". These can be seen as almos... | [
"Not quite. Pluto and Charon appear to be 'locked' into an orbit as a binary planet system. So that's not what would normally be called chaotic - once known, their orbits should be reasonably stable. The effect that this binary system has on their moons means that the moons aren't locked into stable orbits and can ... | [
"My understanding of the mathematics in question goes that you can't have a stable orbit in a Pluto/Charon-like system, unless you were sufficiently far away as to be able to abstract them as a single body, because any three-body problem of that nature inevitably degrades to \"chaos\"."
] |
[
"Math/signal processing question: how do I locate segments in my time series which look similar to my test function? Cross-correlation?"
] | [
false
] | As a simplified example, I have a long function/time series with repeated-sawtooths and I want to locate each individual sawtooth in it. I have a generic single sawtooth (test function) to compare against. The problem is the individual sawtooth segments each have different slopes and different widths and heights. I wan... | [
"There's really not enough information here to help you, but you want a similarity function that captures your personal idea of similarity (which you didn't tell us). Then you can just compare the differences between slices of your time series and your training data.",
"I suggest you just normalise by the average... | [
"I've put more information up. (Thanks for responding)"
] | [
"I am not entirely clear what's going on but maybe you want to do something with wavelets?"
] |
[
"If the sun was blocked out for years by dust, is there any plant or animal life we could survive on?"
] | [
false
] | null | [
"http://www.quora.com/Are-there-any-plants-that-can-survive-without-light",
"If the first post is actually an expert, it suggests parasitic plants could survive.",
"The next question is: how to provide THEM with nutrients, since their host plants would no longer exist",
"Another question: Can we sustain ourse... | [
"Plants can't generally live without light, since photosynthesis is a defining characteristic of a plant. Some can go super dormant, but eventually they'll die because of the normal decaying process of organic molecules.",
"It's worth mentioning that photosynthetic life is a complex adaptation, and life necessar... | [
"He said plant or animal life; suppose he forgot about the fungi? I have always thought fungus would be a potential foodstuff in extreme environments (space/colonization) thanks to its properties and relative ease of cultivation in low light environments, etc. Not sure how nutritious they are in terms of a balanced... |
[
"Is the old concept that one can be stuck in a dream state but doesn't know it (for an extended period of time) possible?"
] | [
false
] | There's the old joke where you whisper in someone's ear "It's a dream" and that sort of thing, to make them believe that their whole life is a dream. Is there any basis that this is possible? (can be from a coma, trauma, psychosis, anything) EDIT: can the mind produce the illusion of a false reality and sustain it. | [
"This is more of a philosophical question, and the generally accepted answer is it's theoretically possible. The problem is you can never prove this theory wrong because even if you determine it's \"scientifically impossible\", that illusion could just be part of the dream. You should read Descartes Meditations and... | [
"I meant more specifically could the brain create the illusion, rather than can someone realize that they are in a dream. Still, great answer!",
"An The Matrix is one of my favorite movie/series. Never thought I'd see Descartes and The Matrix in the same sentence. :P"
] | [
"Research \"lucid dreaming\", a state where one retains conscious awareness during a dream, and some experienced practioners can actually exhibit conscious control over their dreams.",
"http://en.wikipedia.org/wiki/Lucid_dream"
] |
[
"Can silicon from old cpus and gpus be recycled and reused to manufacture the newer ones?"
] | [
false
] | null | [
"In principle yes, but it's not practical. There is no shortage of silicon as an element. Go to a random beach, pick up a handful of sand: Usually a large share of that is silicon dioxide, i.e. ~50% silicon. To be used in computers you need to make that silicon extremely pure, and then add other elements in just th... | [
"No. Creating the circuits in the silicon wafer involves doping it with other atoms, such as boron, arsenic, and phosphorus. There is no way to remove those substances and reuse the wafer. ",
"There wouldn't be much point anyway. Making a pure silicon wafer takes a lot of care and the right technology, but it's r... | [
"There is no way to remove those substances and reuse the wafer.",
"This is not technically true, because the doped layers are a small fraction of the total wafer thickness. They could be polished off. But still, there's no point."
] |
[
"Can anyone explain \"spooky action at a distance\" to me?"
] | [
false
] | I guess I "get" quantum entanglement at a layman's level, but I don't understand how making a measurement at one place affects the other of the pair in another location. I get that once we know the spin of one particle (entity, whatever), we can deduce the spin of the other, but it's just our knowledge that has change... | [
"Edit: The following is a basic experiment that demonstrates entanglement going beyond classical plausibility and apparently necessitating some kind of spooky action at a distance. To be clear, there is of course more to entanglement than this and some aspects are glossed over.",
"Lets take a basic entanglement e... | [
"Actually the particles should have opposite spins for your example to work out that way. An entangled state of one spin up and one spin down is the same as the entangled state of one spin left and one spin right, but two spins up isn't the same as two spins right, for example. Other than that, it works."
] | [
"A better example, I find, involves different locations since it is more obviously in violation of classical physics. This is the example that helped me grok it; hopefully someone else can link a diagram since I'm on my phone.",
"Suppose you have a laser shooting at a semi-silvered mirror, so that half the light ... |
[
"Is there a physical/chemical difference in cold air during the winter and hot air during the summer?"
] | [
false
] | I'm not a smart person (duh) but for example if the air is cold enough is there a possibility that you are breathing frozen CO2 molecules or Oxyge/Nitrogen. For the summer since it is hot can there also be other things in the air. | [
"The composition of the air you breathe is absolutely affected by its temperature. However, within the relatively mild temperature ranges in which humans can live, the changes are not nearly as extreme as your examples.",
"CO2 freezes at around -109F, and elemental nitrogen liquefies at even lower temperatures, b... | [
"Not really, It is one of the reasons why you can get very dry climates in the winter (the water can \"freeze out\" more or less) but CO2 freezes at 195K, and O2/N2 don't even liquify above 100K. I have seen frozen O2 before but that was because of liquid He. You definitely wouldn't be able to breathe that in."
] | [
"A good explanation above, however I would add one point about CO2 levels which may alter slightly in winter due to photosynthesis processes slowing down to a greater extent among the plant population, than animal hibernation does amongst the animal population."
] |
[
"What is vacuum energy and what is the \"vacuum catastrophe\"?"
] | [
false
] | null | [
"Vacuum energy is an energy density associated with empty space. ",
"You may have heard of 'zero-point energy' of quantum mechanical systems, where the state of lowest energy--the ground state--doesn't have zero energy but instead slightly above zero. For example, a classical harmonic oscillator (think mass on a ... | [
"The quantum version of a tiny ball attached to a spring (the ",
"quantum harmonic oscillator",
") has the property that the least energy it can have is not exactly zero, but a little bit higher. You can think of it as due to the famous uncertainty principle (the ball can't ever stop, because then it would have... | [
"True. But high energy effects--special and general relativity, for instance--have only small corrective effects on the low-energy (Newtonian) behavior. In quantum field theory case, high-energy stuff usually does the same thing--e.g. the top quark will give a tiny (unmeasurable) correction to the behavior of elect... |
[
"Can science predict weather better today than a few decades ago?"
] | [
false
] | null | [
"Didn't you ask this same question just an hour ago? The answer is still the same, that we undoubtedly have. ",
"Have a look at this site",
". Drag the mouse to view other parts of the world. Use the scroll button to zoom in and out. Click the [Earth] logo and experiment with various options and move the dis... | [
"Please don't repost questions in the future. We review all posts individually, so it takes awhile for them to appear on the sub. "
] | [
"A lot of the computer modeling software that predicts weather has remained relatively unchanged in the last 15 years. In order to more accurately predict weather these programs would have to be coded again, literally millions of lines of code. By the time that was written, debugged and formed into a new software ... |
[
"If the Earth was not rotating, how different would the gravity we experience be?"
] | [
false
] | Taking into account centripetal forces, how much heavier would we feel? | [
"((40,075 km / 24hr)",
" / 6378.1 km)/ gravity on earth = 3.4*10",
"So at the equator you feel about 3 tenths of a percent lighter because of the rotation than you would have been."
] | [
"The formula for Centripetal acceleration: a = v",
" /r ",
"So your velocity is distance over time which gives us ",
"(circumference of earth / 24hr )",
" so you get the first part (40,075 km / 24hr)",
"then you divide by the radius of the earth 6378.1 km. You get the centripetal acceleration."
] | [
"Can you explain the math and numbers?"
] |
[
"Does anyone know where I could find information about a genetic disorder called a p9:p16 unbalanced translocation?"
] | [
false
] | null | [
"Although I don't know anything about that specific translocation disorder, here is the wikipedia page on Chromosomal Translocation in case you havn't found it yet. Hopefully that can help give you a sense of what is going on.",
"Chromosomal Translocation"
] | [
"Chromosome nomenclature is usually written this way, 9p and 16p.\nIt sounds like you are talking about a case where part of chromosome 9p is missing and instead appears on 16p.",
"This is possibly relevant:\n",
"http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1015677/"
] | [
"TYVM. "
] |
[
"Are there any mathematical operations that don't have an inverse?"
] | [
false
] | Earlier today I was thinking about how I tend to check division using multiplication, subtraction using addition etc. This got me thinking about whether there were any operations that didn't have an inverse. I couldn't think of any off the top of my head, and the only things I know about that I thought could be options... | [
"Sure. What does an inverse g for a function f: X -> Y mean? The function f(x) turns an element x from the set X to an element y from the set Y, and the inverse function g when applied to y will return x. However, this means that there must be at most one x which corresponds to each y. If f(1) and f(2) all return 3... | [
"Any function that maps everything in the domain to the same value (a constant function) is trivially not invertible."
] | [
"If you are claiming that some operation gives you back two possible x-values, then that function is not invertible. The definition of invertible means that for each ",
"-value in the range, there is a ",
" ",
"-value such that f(x) = y.",
"Also, when we write Sqrt(x), we always mean the positive root of ",... |
[
"How were people able to measure the speed of light before today's technology?"
] | [
false
] | null | [
"http://en.wikipedia.org/wiki/Speed_of_light#First_measurement_attempts",
"You may also be interested in the cited works for this section."
] | [
"The first techniques produced accurate results essentially by bouncing the light off of mirrors, and back again. The time difference is measured because some part of the system is undergoing regular motion, and so the experiment reads off the time of flight for the light as a fraction of the period of motion.",
... | [
"Thank you very much."
] |
[
"What are virtual particles? How are they theoretically real yet undetectable?"
] | [
false
] | null | [
"Virtual particles are undetectable by definition. They are mathematical artifacts of ",
" methods of calculating ",
" observables. Specifically, they show up in perturbation theory.",
"In quantum mechanics, when you want to calculate the probability amplitude for a system to evolve from some initial state to... | [
"Assume you have two infinite conducting plates, separated by some distance d, and consider a situation where there are no photons anywhere in space. The state of the electromagnetic field in each of the three regions of space is the vacuum state (the state of no particles). In quantum field theory, the vacuum stat... | [
"This is the clearest explanation I’ve ever seen of what virtual particles are, thanks."
] |
[
"Can our eyes feel temperature?"
] | [
false
] | I know this sounds dumb but I noticed today while it was near freezing that my eyes are the only part of my face that wasn’t immediately or subsequently cold. Is this just because we blink a lot, or smaller blood vessels, or what? | [
"Yes. The cornea (the transparent part over the iris and pupil) has unmyelinated nerve endings sensitive to touch, temperature and chemicals. Triggering those nerves causes an involuntary reflex to close the eyelid. The sclera (the white part) also has these same nerves, and similar signals will also trigger the in... | [
"The body doesn’t actually perceive temperature, it perceives ",
". Let’s say you have a desk in the middle of a room that’s 72F. Everything will have a temperature of 72F if you measure it, right? But if you touch the wood part of the desk and the metal part, which will feel colder? The metal will feel cooler be... | [
"Eye doctor here - Several factors will affect this. First: the answer to the question is yes. Second: It's complicated. The Corneas and conjunctiva are completely bathed in tears and under normal conditions, those tears protect the surface from the temperature changes. The tears themselves have water, oil, and... |
[
"If salt is toxic to most plants why do plants by roadways that are heavily salted year after year seem to be unaffected?"
] | [
false
] | It seems that over the years the soil around the road would accumulate a lot of salt. | [
"They actually can be affected, you just don't notice.",
"Halophytes",
" are plants more tolerant of salts than others. These plants can slowly begin to takeover in roadside ditches were road salt accumulates, but if you weren't looking for them you'd never notice.",
"It's out of my area of expertise, but I ... | [
"oenothera humifusa (seabeach evening primrose), and species of amaranths are starting to be found along roadsides. These species are found in quantity in salty environments like beach dunes. An ecology class that I took had us document and study these and similar plants, and I now notice them along almost every ro... | [
"OneShotHelpful is correct. Some plants are more tolerant to salt than others. If you live in an area that salts its roads during winter, you might have noticed how the same handful of plants (like Mock Orange) are planted in all medians, parking lot 'gardens', highway ditches, etc. This is because these are really... |
[
"I’m searching for the friction coefficient of paper on paper and of paper on steel... Does anyone know a good website where I could find it ? Or even an easy way to compute it by myself ?"
] | [
false
] | null | [
"Hi Pas_Steak thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the follo... | [
"‘Engineering’"
] | [
"Engineering"
] |
[
"Whats the best way to send radio signals over 400 miles?"
] | [
false
] | null | [
"VLF waves. I doubt it would be feasible to obtain an antenna for personal use, however.",
"Unfortunately, your question is quite limited in scope. If you have a more specific question, feel free to make a new submission.",
"Cheers."
] | [
"Hi thanks for the quick response. basically my friend and i are Linux hobbyists so to say, and we just think it would be cool to be able to send decentralised messages via encrypted radio signals. this is more of a experiment for the fun of it but i thought i would ask people on here what the most likely method wo... | [
"If range is your primary requirement, VLF seems like a dead-end. I think it would be considerably easier to conduct the experiment in a localised environment, where you can use cheap WiFi/Bluetooth/etc. devices.",
"Otherwise, the power required - even for directional antennas - seems prohibitive in a hobbyist co... |
[
"How clearly can we see objects in other galaxies?"
] | [
false
] | I have always been curious as to just what kind of details we can see, and what can only be theorized. For instance, we can count how many moons Saturn has, but can we tell the same for a planet in another solar system? To my understanding it would really come down to just how much light is being reflected from these p... | [
"Our telescope resolution is what limits us to see detail on objects in other galaxies. An object can be incredibly bright, but unless the optics you're using have the proper resolving power, it will look like a big bright blur.",
"Telescopes have specific resolution that depend on their size and ability to see ... | [
"In the very big picture, the brighter an object is, the farther away we can still identify it. We can identify individual stars in nearby galaxies if they're bright. We can identify planets around nearby stars if they're bright. All known moons are in the solar system.",
"But brightness also depends on at wha... | [
"Wow thank you for that! I'm going to look more into this. "
] |
[
"If a person is breathing pure O2 will they become flammable?"
] | [
false
] | null | [
"No.",
"It is used as a treatment in diving if you have too much nitrogen in your blood from diving.\n",
"http://en.wikipedia.org/wiki/Decompression_sickness",
"Though you can hurt yourself if you inhale pure oxygen at higher pressures.\n",
"http://en.wikipedia.org/wiki/Oxygen_toxicity"
] | [
"In terms of using hyperbaric chambers for decompression sickness, it is not just about the O2 content. Decompression sickness is due to a quick rise of a scuba diver to the surface. As you reach the surface, the atmospheric pressure decreases, allowing more nitrogen to bubble out. (think about a soda can being ... | [
"This isn't really correct, while 100% pure oxygen will not combust, it is misleading to say \"In that case, oxygen wouldn't be flammable\".",
"A combustion reaction is Fuel + Oxygen -> Heat + Water + Carbon Dioxide.",
"\nIn the case presented \"In pure O2, would your skin be flammable\", yes, it could. With sk... |
[
"So were are learning about the Hodgkin-Huxley model of K channels; but it is from a long time ago. Are their models still correct nowadays?"
] | [
false
] | I'm just wondering if current evidence supports their ideas; or if new studies have shown it to be wrong (like the Bhor model of atoms) | [
"We did a computer simulation of the H-H model in a quantitative physiology class in undergrad and let me just say that it is absolutely incredible.",
"The full differential equation almost perfectly mimics the actual action potential including shape, amplitude, refractory periods, threshold effect, etc. ",
"I ... | [
"The original HH model included only a transient Na+ current, a delayed-rectifier K+ current, and a leak current. The idea behind the model - channels that open and close under various conditions, whether simply voltage gated or more complex, is still correct. It has, however, been significantly extended to include... | [
"happy inerwebz birthday"
] |
[
"If Earth had rings like Saturn would the night time be significantly brighter due to reflection from the Sun?"
] | [
false
] | [deleted] | [
"Ron Miller created some cool ",
"images",
" of what rings around Earh might look like.",
"Interestingly, the moon began its life around Earth as a ring that coalesced and will likely end up the same way in the future when our Sun transitions to its red giant phase. The drag caused by the sun's atmosphere wi... | [
"But I just can't compute that in my head. We have a moon. If I took that moon and cracked it in 4, keeping the same speed, and placing all the pieces at 90 degree angels, why wont that work?",
"If it works, why not do it a thousand more times.",
"Also we already have rings. Man made. Thousands of satellites. W... | [
"Simple answer to both questions - both the effects would be similar, depending on the density of the rings. If they were dense enough, they would reflect light at night (except where Earth casts a shadow on them), and in turn they'd cast a shadow on Earth during the day. Of course that's assuming Earth could have ... |
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