title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"If we discovered and traveled to a habitable planet outside of our Solar System, finding vegetation, could we figure out if something is nontoxic/edible without eating it?"
] | [
false
] | What kind of tests could we run to figure out if extraterrestrial vegetation is edible? Would our "earth" toxicology tests work? If we came across compounds never before seen, how do we know if they are poisonous? | [
"Peruse a ",
"list of organic chemicals",
" if you're curious. Only a tiny percentage are non-poisonous, hence most successful lifeforms have far more skin than mouth.",
"As for degrading it with gastric acid... try that on ammonia, or sulfuric acid. Outside a rather small pH range, you'd be dead long before ... | [
"I remember hearing that aboriginals in Australia would test food items for toxicity by feeding it to another animal and then following that animal to see what would happen. If that didn't work they would also rub the food on a sensitive portion of their body (inner thigh, armpit, etc.) and see if their skin react... | [
"Am I correct in thinking that while we couldn't eat them, we could still use them for fuel? Carbohydrates + combustion reaction works regardless of what planet you're on."
] |
[
"What distinguishes time from the other 3 spatial dimensions? Couldn't time just be seen as a 4th spatial dimension?"
] | [
false
] | null | [
"There's a key difference between 4D space and (3+1)D spacetime. If you were to just take the usual three Cartesian coordinates and add a fourth (u), the metric for that space would be:",
"ds",
" = dx",
" + dy",
" + dz",
" + du",
".",
"You can think of this as being the Pythagorean theorem of 4D space... | [
"You can plot a \"faster-than-light\" worldline on a spacetime diagram without it physically meaning anything. It will remain faster-than-light under any transformation (you can change whether it's going forwards or backwards in time, though)."
] | [
"A universe where time is a space",
" dimension would be a very different place:",
"https://www.gregegan.net/ORTHOGONAL/ORTHOGONAL.html",
"Easy time travel, electrical fields that oscillate sign over distance, and collisions that require a third particle to spontaneously arrive at just the right time are a fe... |
[
"How are spacesuits sealed from the vacuum of space when assembled?"
] | [
false
] | I understand that the space suit provides air pressure to keep the fluids in your body in a liquid state, and that the suits are assembled in different pieces for the limbs and such. But how are these separate pieces sealed from the vacuum of space when assembled? (i.e. where the separate pieces connect) | [
"The same way as docking. Joints lock tightly so air can't escape. It's like putting your finger over the neck of a bottle and flip it upside down. The liquid inside won't come out because your finger is in the way. ",
"Basically, a space suit is an upside-down water bottle with a finger on the neck. "
] | [
"Thank you. I just found some information about the \"Quick Connection Rings\". If one piece of the spacesuit is compromised/punctured, will the rest of the suit be compromised? I know that there are many pieces involved. "
] | [
"One of the things that you have to understand is that space suits aren't at that high of a pressure, otherwise the astronaut in them wouldn't have the strength to bend his fingers and the like. The PLSS backpack used during the Apollo Moonwalks maintained the suit at 4.3psi (one atmosphere is about 15psi). The sui... |
[
"Does any amount of mold on food indicate that the entire thing has gone bad?"
] | [
false
] | I've heard that by the time you can see visible mold growth on some parts of a bit of food, the rest of it is already colonized by an unhealthy amount which has simply not yet grown to visible concentrations. Is there any merit to this? | [
"Depends on the food - the USDA ",
"has a neat chart",
" that explains what's safe to eat with mold."
] | [
"Depends on the food, and the quantity you are talking about. A bit of mold on the outside of a hard cheese is nothing to worry about. Mold on bread is more likely to be present throughout the loaf. Mold on one corner of a 100kg side of beef may have penetrated a bit, but is irrelevant to what's going on at the ... | [
"Wow, that's really interesting. Thanks for sharing!"
] |
[
"I tend to focus a lot more on the way the people move and speak in tv shows and film than in the story. Is this normal?"
] | [
false
] | null | [
"Hello,",
"We can't offer personal evaluations or advice here."
] | [
"Do you know any sub that could?"
] | [
"You could try ",
"/r/answers",
"."
] |
[
"How do water softeners work?"
] | [
false
] | How exactly do water softeners soften water? I know that they change atoms around and have something to do with ions of some sort. | [
"They use ion exchange resins. The resins are designed so that it initially has sodium ions at the resin's active sites. When exposed to hard water the hard ions (Calcium and Magnesium) take the sodium's spot on the resin which releases the sodium ions back into the water. ",
"In a nut shell it just swaps out... | [
"All water softeners use ion-exchange mechanisms to take the ions responsible for hard water (usually calcium and magnesium) and replace them with another ion like sodium. As for how they do that, well... It varies.",
"Off the top of my head, I can think of two different methods used for ion exchanges. The first ... | [
"Retail isn't that bad... (lol) Thanks."
] |
[
"Will the continents shift, break apart, or change like they did with Pangea?"
] | [
false
] | null | [
"Will the continents shift,",
"The continents are part of ",
"tectonic plates",
", which are rigid sections of ",
"lithosphere",
" that move together. The plates are constantly moving and we can measure their motion with GPS stations, e.g. ",
"this page",
" includes a map where you can view the rate o... | [
"Thanks for the detailed answer! I hope I'm not getting annoying here, but one thing that interests me is the local fault system in my neighbourhood - the Eger Graben. From what I know from my limited geological readings, it's a remnant of the hercynian orogenesis which built up the middle German mountain ranges th... | [
"As far as I know, there is no formal definition of a strict size cut off or something like that as to when you would call something a plate vs a microplate. For something to be a microplate, it needs to be 'plate-like', meaning that it needs to be a section of lithosphere whose movement can be described by a singl... |
[
"If a nuclear weapon is made by splitting an atom, why is it only possible with uranium?"
] | [
false
] | null | [
"There are a few different nuclides which can be used to make fission bombs (uranium-235, plutonium-239, etc.)."
] | [
"What about those elements make that possible?"
] | [
"Those particular nuclides readily undergo neutron induced fission reactions."
] |
[
"Do nonpolar organic solvents denature proteins, and if so how?"
] | [
false
] | Today in my O. Chem lab, we were using an enzyme called Acylase I to turn an alcohol + vinyl acetate into an ester, and whatever. So anyway, we put the alcohol, the vinyl acetate and some acylase I into our reaction containers, along with some Hexane. And this one dude asked our TA how the hexane doesn't denature the Acylase. I've never taken a biochem class or a microbiology class, but my speculation was that a nonpolar solvent wouldn't really mess with anything. But the dude said hydrophobic molecules prevented Van Der Waals interactions, and were used a first step in protein denaturation. The TA himself had no idea what effect the hexane would have/wouldn't have on the enzyme. So, yeah. | [
"Nonpolar organic solvents certainly ",
" denature proteins, although whether they do and to what extent depends entirely on the protein. ",
"Proteins consist of amino acid residues, which can be polar or nonpolar (and charged as well). If a protein has a lot of polar/charged amino acid residues on its surface,... | [
"Probably there would be an interaction with any amino acid side chains that are aliphatic e.g. valine, phenylalanine, leucine. This would cause a change in shape and therefore reduce the activity of the enzyme on the substrate(s). ",
"I wonder though if by removing the hexane, or other non polar solvent you coul... | [
"If the enzyme is normally in water, it will have polar groups on the outside (usually). This means if you put it into a non polar solvent, there won't be any sort of pressure on the enzyme to maintain its shape, and it could become denatured. It depends on the protein though."
] |
[
"How real was the risk with turning on of the higgs collider?"
] | [
false
] | null | [
"You are talking about the Large Hadron Collider (LHC).",
"The kind of reactions that scientist create in the LHC occur daily in our atmosphere when cosmic rays strike earth. If there was any truth to any of the doomsday scenarios associated with turning on the LHC, then these scenarios would have already be trig... | [
"As far as I remember no scientists said there was danger. Hawking was taking about the possibility of micro-blackholes occuring during the reactions. But they were never a danger. By definition they would be unstable and ",
" disintegrate. ",
"He only mentioned it because it might mean that Hawking Radiation ... | [
"The real danger was from catastrophic sealing failure resulting in very costly explosions. There was no real danger to our planet from the experiments performed. Just danger to the budget of the LHC and lots of wasted helium. "
] |
[
"Why don't we have ceramic engines?"
] | [
false
] | Ceramics can be heated to higher tempratures than common engine materials without melting. By doing so increasing the efficiency of the engine. What's stopping us? | [
"While ceramics are extremely heat resistant and much harder than (most) metals, they're also very brittle. I just don't think they would be able to stand up to the punishment that steel can.",
"It also isn't exactly the easiest material to work with, requiring very specialized machinery and techniques. I serio... | [
"Besides brittleness, there's a bit of a problem with conductivity. Sure ceramics can have very high melting points, but combustion temperatures can get just as high pretty easily. That's a big problem if your refractory material can't get rid of its heat. Metals on the other hand have lower melting points but a... | [
"There have actually been a couple ceramic engines made by researchers (in academia and industry). Lots of good info on how the properties of selected ceramics are beneficial/disadvantageous [here].(",
"http://ceramicrotaryengines.com/",
")",
"I seriously doubt the efficiency gains would come close to offsett... |
[
"Do we feel the planet moving? Does the Coriolis Effect affect the way we move?"
] | [
false
] | I find it odd that so many things that humans do, we do counterclockswise. NASCAR, track bicycle racing, Whirling Dervishes, circumambulating the Kaaba in Mecca... Does it have to do with the predominantly right-handedness of the population? Or is right-handedness a result of the Coriolis Effect? | [
"Short answer, No.",
"The coriolis effect is small and drowned out by other sources in most cases.",
"Only on large distances and long times (e.g. cyclones) does it produce noticeable effects.",
"As for right handedness, please not that the cradle of humankind is most probably africa at or below equator. The... | [
"Does the foucault pendulum work with the same principle of coriolis effect? "
] | [
"Coriolis also affects very fast moving objects.. ",
"If you were to fly at mach 15 through the upper atmosphere you would have to compensate for the apparent force. "
] |
[
"What's actually happening when you age wine?"
] | [
false
] | null | [
"some of the other answers in here are talking about fermentation and aging in barrel, both of which happen before a wine is actually bottled and sold. ",
"here are some of the things that happen as wine ages in the bottle:",
"color: newly released red wines are often more bright red-purple, while aged wines t... | [
"only a small percentage are meant to be aged (high-end bordeaux, burgundy, italian, napa, etc).",
"What wines age the best? How long can they be aged before the quality begins to decline? For consumers is it worth buying modern wine with the intent to age, or is the difference not very noticable these days?",
... | [
"Sulfites is correct, however, fermentation only takes about a month to complete."
] |
[
"Is there any truth to the claim that Earth is losing it's magnetic field?"
] | [
false
] | I have seen a couple of internet articles, but I wanted to know the truth behind this. What timescale are we looking at? What are the effects of this going to be on society and daily life? | [
"Well, the magnetic field will dissipate, but this will be on the time-scale of billions of years in the future. The reason why this is, is because the magnetic field is created by the flow of current, induced inside the outer liquid core of Earth (which is comprised of Iron and Nickel). As the Earth cools off and ... | [
"National Geographic may say it, but I would be more interested with probing the sources of their article. Keep in mind that our instrumentation back in 1845 was limited, and with that comes great err in calculations of strengths such as magnetic fields, especially when a magnetic field such as Earth's (which is no... | [
"Well....",
"On a compass, you see, the magnetic north part of the compass points in a certain direction. As you know, north is attracted to south. Therefore the north end of a compass would naturally point to a magnetic south pole. So, the \"North Pole\" as we would call it is actually closest to a magnetic sout... |
[
"What is considered to be the most destructive or powerful thing in the universe?"
] | [
false
] | null | [
"Well, any black hole, let alone a supermassive one, is powerful enough to destroy more or less anything that gets too close to it. On the other hand, contrary to the sci-fi depiction, they aren't like vacuum cleaners, so they don't actively suck things in to their doom. Basically things that get close enough fall ... | [
"The (presumed) black hole at the center of the milky way exists in a compact astronomical radio source called Sagittarius A* (just an FYI in case you want to look up more on it on your own).",
"I don't know what the exact boundaries of it are, but the star S2 orbits it at about 17 light hours, (about 0.002 light... | [
"The (presumed) black hole at the center of the milky way exists in a compact astronomical radio source called Sagittarius A* (just an FYI in case you want to look up more on it on your own).",
"I don't know what the exact boundaries of it are, but the star S2 orbits it at about 17 light hours, (about 0.002 light... |
[
"Does the neurotransmitter has to change firing rate to have real effect?"
] | [
false
] | Does the neurotransmitter has to change firing rate of neuron that receives it to have real effect? Are there neurotransmitters that don't change firing rates of neurons even indirectly but cause noticeable change in brain behavior? | [
"If a neurotransmitter never changed the firing rate of the postsynaptic neuron at any point in time, the answer would be yes. Often neurotransmitters have metabotropic (as opposed to ionotropic or ion channel based) effects that are subtle and/or do more to modulate potential for plasticity than to directly impact... | [
"The only direct effect of a neurotransmitter is to activate one or more types of synaptic receptors (by definition). So yes and no."
] | [
"Why were you downvoted?"
] |
[
"About AC and DC in homes:"
] | [
false
] | This is something I've wondered for a long time. Bottom line: I hate AC/DC converter bricks. They're everywhere and every gadget you own save a few computer/gaming peripherals need them. I think it dawned on my when I my mom used a wall-charger in her car to charge her cell phone. She had to use an inverter to do it. What that means is: 1) The car puts out 12V DC power to the lighter plug 2) Her inverter converts the 12V DC to AC 3) She plugs in the brick to convert the AC back to DC so she can charge her phone!? She did this because she didn't have a car charger for it at the time. This is insanity and I realized it's only slightly less insane at home. I understand that AC can be transmitted through lines much more efficiently to our homes, but why does it have to stay AC once it gets here? Why can't I have a standardized 12V DC wall plug and eliminate a box full of these stupid AC/DC converter bricks? DC/DC converters to step the voltage up or down are much smaller and I have to believe are more efficient right? Seriously, sitting at home right now, name something that has to have AC input in your home that isn't just converting it to DC before it uses it. All I can think of is the real heavy machinery like washers/dryers which might be using AC motors. Is there a problem with power transmission (or anything else) over short distances I might encounter if all my home's plugs were DC with one or two exceptions for ubiquitous AC appliances? | [
"If I remember right, AC motors are usually smaller. Most DC electronics have to do with circuit boards, and AC would not work with them. But any appliance that has a pump or motor needs AC unless the ENTIRE industry were to change over. "
] | [
"I work as an engineer at a power supply company (we make wall inverters that charge your phones and devices) ",
"the primary concern right now is that every device out there requires different voltages. You have cell phone chargers running off 5V, your radio running off 12V, your power drill charging on 24V, an... | [
"they're not. Take a look at the AC-DC converter for an iphone/ipod. have you seen the size of those things?",
"There are two main types of DC-DC converters. Linear and Switching. For a linear converter, the difference in voltage is dissipated as heat, therefore requiring a fairly large heat sink to meet safe... |
[
"Are sociopaths exclusive to humans?"
] | [
false
] | [deleted] | [
"Maybe. I'm currently involved in a project that is investigating some genetic polymorphism that have been linked with sociopathy in humans in a nonhuman primate. I won't say it results in animal \"sociopathy.\" The word sociopathy is frequently regarded as the ontogenetic manifestation of psychopathy, which evi... | [
"http://www.pbfcomics.com/?cid=PBF033-Deer_Laser_Eye.jpg"
] | [
"Very interesting, and thanks!",
"(in order to flout social conventions, there first must actually be social conventions to flout)",
"Now, forgive me if I sound ignorant or ill-informed, but don't certain animals, like chimps and dolphins have social conventions? Or am I thinking about their societies in the w... |
[
"Why does the strong force increase with distance whilst the residual strong force decrease with distance?"
] | [
false
] | [deleted] | [
"The residual strong force is analogous to the Van der Waals force. ",
"A system of two equal and opposite charges near each other is called an ",
"electric dipole",
". The total charge of the dipole is zero, so you might think that far away, the electric field produced by the dipole is small. And that would ... | [
"Well \"beam\" makes sense to me, but I work around lots of charged particle beams so maybe I'm biased."
] | [
"Sure, you could make a case for all four. But it's clear they wanted you to pick protons."
] |
[
"What determines what wavelength of light is reflected from object?"
] | [
false
] | If i have a green apple, shined on by light from sun. The apple appears green. Because all wavelengths of light are absorbed except for some that appear green to us. But what determines the color of the apple? Is it the size of the molecules on the apple surface? | [
"The transmission/reflection spectrum of a material is a function of the ",
"electronic structure",
" of the molecules composing it. You can imagine an electron as a charge on a harmonic potential; the electric field in passing light excites the electron into an oscillatory motion. When the frequency of the exc... | [
"TL;DR: it's the number of protons in most common atoms on the reflective layer of apple surface. The most outer layer is transparent wax (try to scrub apple with knife, it's fun).",
"Wavelength of any photon is determined by it's energy. wavelength = planks constant * speed of light / energy.",
"What defines e... | [
"This part is well known: under ideal light source that emits all frequencies evenly, an \"ideal red\" object (absorbing all frequencies except some red range) will receive more energy than same size/shape/etc \"ideal green\" object. ",
"https://depts.washington.edu/cmditr/modules/lum/600px-Emspectrum_energy.jpg"... |
[
"Why do scientists hypothesize dark matter and not some non-matter phenomenon that generates gravity? I.e. why consider it \"matter\" at all? Or is \"dark matter\" just short for \"gravity-producing phenomenon\"?"
] | [
false
] | For example maybe there's just an interaction we don't know about that produces gravity. Or is that an unlikely or impossible scenario? From Wikipedia I see and and , but it's unclear why these are so marginalized. | [
"They're marginalized for two main reasons:",
"1) They don't explain the data better than (cold) dark matter does, and lately have often had a harder time explaining several observations, and",
"2) They're ugly as sin. The equations governing a theory like TeVeS are just plain gross, and the only reason anyone ... | [
"I ",
"answered a similar question",
" two days ago. MoND was proposed in the 80s when the \"missing mass\" problem was really starting to make itself clear, but lots of other observations over the last three decades have really favored dark matter just being some hard to see particle (or class of particles). S... | [
"the idea of dark matter being some new particle that's hard to see isn't really that weird. It's actually one of the simplest possible solutions.",
"It's also not unprecedented. The neutrino was predicted to exist decades before it was directly detected, and it's similar to the particles that are expected to mak... |
[
"When synthesizing new elements, how do scientists know about the number of atoms they produced and how do they measure the rate of decay?"
] | [
false
] | I'm very sorry if this is a noob question. I never paid attention in chemistry class. Anyway, here we go: I've been watching some videos about the synthetization of Ununoctium / Oganesson recently and got some questions: In the video I watched, they said that they synthesized x atoms of Ununoctium. How can you measure something this small? Also, how do you measure the time for it to decay, which is also a very small time? | [
"How can you measure something this small?",
"The decay products of these extremely heavy nuclei hit your detectors. Then you can plot histograms, apply gates, and eliminate events which did not come from the nucleus you're interested in. Once you've eliminated all extraneous events, you just count the number tha... | [
"Nice paper, let me try an ELI5 version:",
"Superheavy elements are produced in fusion reactions, where you hit a heavy nucleus (say, a californium nucleus with 98 protons and 154 neutrons) with a lighter nucleus, in this case the choice of calcium-48 (20 protons and 28 neutrons) is popular.",
"The fusion of th... | [
"Typical Si detectors are 300 micrometer thick. Recoil energies are of the order of 5-40 MeV (depending on the reaction, target thickness, vacuum vs gas-filled separator etc), so implantation depths are a few micrometer. ",
"Transmissions are quite high for the channel of interest: 40% and more are not difficult,... |
[
"How do benzodiazepines cause memory impairments? Specifically spatial memory impairments?"
] | [
false
] | So I know the mechanism of action for the therapeutic effects of benzodiazepines is by binding to the GABA-A receptors. I was wondering what the mechanism of action for some of the side effects caused by benzo's are. More specifically what happens chemically that leads to spatial memory deficits in rats and humans? | [
"Alright, so the best way to explain this is probably by plasticity. As neurons fire, they become stronger. This process can occur over a long period of time, or over milliseconds. In the hippocampus, which is the section of the brain that deals with memory, this process of plasticity is directly related to the ... | [
"I don't think there is 1 thing that happens, it's a system change. If you are looking for a schematic, I'm sure something exists that will show you the molecular pathway, but I can assure you that looking at that is mind numbing:) (Btw, I'm a neuroscientist and who has worked/published on opioids and spatial memor... | [
"Would you be able to equate a neuron as being a switch that is either on or off? What you said made me think of something IT related."
] |
[
"Do trees grow at a constant rate?"
] | [
false
] | This struck me today when I was looking at some young saplings near old, established trees. Does their growth slow over time? Or does it only appear to slow because there's so much more to them and their growth remains constant? | [
"Material scientist here. Absolutely not. Tress grow at different rates. The evidence can be seen in unequal thickness of growth rings. During drought or tough conditions, rings are compacted, during wetter seasons rings can be quite large. Often a ring will be black from forest fires etc. So many other factors com... | [
"No. They require things to grow. In order for the tree to increase its mass, it must take in matter. If the tree is not eating very well, it will grow slower. Other things like temperature affect the growth rate as well because a lack of heat can slow biochemical reactions and too much heat can denature proteins a... | [
"It does, thankyou!",
"\nWhat if, hypothetically, all conditions were perfect?"
] |
[
"When you put your fingers on both leads of a battery and are grounded why do you not get shocked?"
] | [
false
] | Title | [
"Ohm's law states that the voltage (V) is equal to the product of the resistance (R) and the current (I)",
"V = I × R",
"Rearranging that, the current is equal to the quotient of the voltage divided by the resistance",
"I = V ÷ R",
"NIOSH states that the resistance of an average human body is 100 000 ohms (... | [
"Ah this is what I assumed but I didn't think skin resistance was so high. Thank you for your detailed explanation "
] | [
"You can get shocked if you put a 9v battery on your tongue you can feel it tingle. The reason you cant feel a 9v when you touch it to your finger is that it is not strong enough to overcome the resistance of your body."
] |
[
"If all the races of the world continuously cross-bread with each other would we eventually get one composite race?"
] | [
false
] | null | [
"No, because race is a sociological concept, not a scientific one. Now if you asked how skin color would turn out...I'd say there would always be variations in color, even if they are shades of brown. In which case human nature would probably take over and create \"race\" out of natural variation. "
] | [
"um, we already can't group traits together like that. "
] | [
"um, we already can't group traits together like that. "
] |
[
"Can you force Psychopathy?"
] | [
false
] | If a certain very traumatic or life changing event happens, can it force Psychopathy(turn your amygdala off) or can it speed up the rate for developing Psychopathy? | [
"If a certain very traumatic or life changing event happens,",
"psychopathology after traumatic stress -> cf. post-traumatic stress disorder (PTSD)",
"can it force Psychopathy(turn your amygdala off)",
"there's a lot more to it than reduced amygdala activity in certain conditions",
"can it speed up the rate... | [
"Thanks so much! Just needed some information on this topic for a essay for psychology. "
] | [
"I am confused by what you mean by \"psychopathy\" and defining it as \"turning the amygdala off\". Psychopathy is basically another word for mental illness.",
"Are you asking if traumatic or large events can cause emotional blunting and problems with memory consolidation? If so, then yes. But please define what ... |
[
"Is cannibalism bad for you?"
] | [
false
] | I was watching the Book of Eli, and it shows people who have eaten a lot of human flesh have "the shakes" (their hands tremble). Is there any known harm caused by human cannibalism? | [
"I've never seen the movie, but it sounds like it is referencing ",
"kuru",
", a prion disease (think mad cow disease) that causes trembling that became transmitted in a Papua New Guinea tribe because of their cannabalistic practices."
] | [
"I don't know specifically, but my intuition would say no. Why would human meat be that much different from beef or pork? And we won't be producing anything toxic to humans, since the original human had to live too.",
"However, I guess there might be an increased risk of transmissible prion disease from eating hu... | [
"There's increased risk of viral infections. Cross species viral infections do happen, but it's common for virus not to cross species boundaries.",
"Edit I am not a biologist, nor do I play one on TV."
] |
[
"Did the universe really begin with a singularity?"
] | [
false
] | null | [
"\"Singularity\" just means some point in a field equation where the field value goes infinite. That's all it means.",
"There are cosmological models in which some term in some equation goes infinite at ",
" = 0, and models in which none do. They are all, to within the limits of our ability to make observations... | [
"Since",
"there is currently no theoretical model that explains the earliest moments of the universe's existence because of a lack of a testable theory of quantum gravity [1]",
"it is difficult to answer this question with certainty (which I deduce you want, having used the word \"really\"). However, it is \"be... | [
"Thanks. I ask because I read an ",
"article by Victor J. Stenger",
" (page 2, line 36) where he claims that no cosmologist nowadays would tell you that the universe began with a singularity and I am puzzled."
] |
[
"Why do cysts form and why is the body unable to remove / heal / rid itself of said cysts?"
] | [
false
] | null | [
"Cysts are more typically seen as fluid filled growths as opposed to a granuloma or abscess which is more likely to refer to a \"walled off\" infection of typically bacteria. One reason why they form is the body does it on purpose, if the immune system \"thinks\" it can't handle the disease (best example is TB) it ... | [
"So if someone is prone to cysts what does that usually mean?"
] | [
"Yes. I figured it was an inability to rid what it contains. Once the barrier is formed is it periodically maintained or does the body allow it to gradually break down and \"check\" if what is contained remains. The cyst itself isn't a means to create an inhospitable environment as in the TV can sustain itself ther... |
[
"What is laughter, and why do we do it?"
] | [
false
] | null | [
"The behavior of laughing most likely came about as a means of communication. The general purpose would have been to inform others of false predator alarms. Danger was expected, and when nothing happened, laughter was a sign that any danger had passed or was never there. Laughter still serves its purpose as a respo... | [
"Important distinction: Laughter is a form of communication, but not classified as a part of language. It doesn't take place in the \"language\" parts of the brain. This is why babies know how to laugh before learning any other form of communication. It's why all cultures have people that laugh even though all ... | [
"Laughter seems to exist as a stress relieving mechanism. It is often a barrier to empathy ( when empathy is the sharing of someone else's pain/trouble/suffering) that's why it can be so easy to laugh at someone else's bad fortune (and why its frown upon to indulge yourself into too much mean laughter: We dont like... |
[
"Can flies detect electric currents in the air?"
] | [
false
] | As per title. Observation was made regarding a behavioral change. | [
"Usually not, but in special conditions they can, like when fatally close to an electric bugzapper. The electric field gradient spreads their legs and wings, at least in the case of mosquitos. ",
"Please provide the details of your observation: how many amperes and at what distance?"
] | [
"More than once flies have detected this zapper from across the room. They instantly go into 2 modes of behavior: \nA.) Freak out panic mode where they will go from the \"lost circle buzz\" into a more chaotic wall bounce.\nB.) Hiding down low in places with cover.",
"I've observed it many times. Dunno the amps b... | [
"Follow up questions: Do you know if its the electrical current, is there a light going on with the zapper that might be affecting their behavior (visible or UV spectrum)? Have you tried turning the zapper on and off to see if the flies will revert to their previous behavior once you have turned it off? Then turn ... |
[
"Followup from \"The Roundest Object in the World\" video... why is the material (silicon-28) to make it so expensive and how would they make it?"
] | [
false
] | This was recently posted on , and I'm not so interested in the shape... I was wondering about why the cost was so astronomical for the silicon (which has a market price of ~$25/kg of standard polysilicon)? | [
"Silicon is dirt cheap. Literally. Almost a third of the volume of the Earth's crust is silicon. There's plenty out there.",
"The kicker here is the extraordinary high purity. That sphere is one of the purest macroscopic objects, elementally and isotopically speaking, that exists on Earth, if not in the Univ... | [
"That said, the industry exists to make silicon elementally pure. Isotopically pure seems to be (by the other comments) the proverbial kicker here. Obviously, their enrichment schemes are rather lab-scale at this point... what's to keep someone from making comercially viable Si-28 for, say, the electronics market... | [
"So what your saying is true, the electronics market uses silicon thats >99% pure, HOWEVER, it is not isotopically pure. Now, there are (from my understanding) no advantages, or very minimal, to having an isotopically pure silicon. That combined with the fact it is so expensive to produce is why it is not used in e... |
[
"Is there a way to universally measure time that is seperate from earth and it's rotation around the sun?"
] | [
false
] | null | [
"yup. \"Since 1967, the second has been defined to be: the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom\" en.wikipedia.org/wiki/Second"
] | [
"A meter is defined in terms of the speed of light, so yes, we already do.",
"It should be noted that due to relativity, even though the speed of light is always the same, and a second is always the same.. two people will measure the same thing and get two different answers, and they'll both be right. "
] | [
"Yes, you can use an ",
"atomic clock",
", which exploits ",
"electron transitions",
". The time between jumps is distributed as an exponential distribution. If you know the theoretical time between jumps (t, in (nano)seconds), counting jumps of a known, reasonably large, number of atoms (n) will allow yo... |
[
"Infinite Hotel Paradox. Is this a good explanation of Infinity or does it violate the thought of infinity?"
] | [
false
] | I found this while on a you tube binge. I couldn't help but feel this thought experiment is... wrong. I felt I grasped infinity pretty well, but does my explanation make sense, or am I missing a fundamental part of this thought experiment? I was thinking (and posted on youtube.) "If the hotel is full though that assumes there are already infinity guest bookings. Adding another infinite amount of guests is saying you want to cram 2*infinity people into infinity rooms. I would assume since both the guests and the rooms are infinite that you are adding 2 people every time 1 room is created. This problem doesn't make sense because instead of putting the people into a room they are instead moving between rooms and not actually put up in their own room. The freeing up of 1,3,5,7,9 etc..... doesn't actually free them up. You created a wave of people moving. lets assume you instantly told, everyone they are going to move and you moved them, Because it's infinite you'll never free up enough space (the hotel is occupied at every number you get to) for another infinite amount of people. I'll explain what this has done another way. Two strings that are infinitely long, one red, one blue. Both wish to occupy the same space. Red string is already in that space, to create room for blue string you create a wave, and feed blue into the now empty space. The red wave will go on infinitely and you will infinitely fill in blue for red. You never finish putting blue string in because it's infinite, and red string is never again "at rest," because it is constantly moving for blue. I understand it's supposed to be a way to illustrate how large infinity is, but surely there has got to be a better way to explain this." Edit: The more answers I get explaining unique ways of understanding this issue I get the more fraking excited I am by the concept. You guys/gals Rock!!! | [
"The nature of infinity is such that adding to it doesn't make it larger. Subtracting from it doesn't make it smaller.",
"So (2 * ",
" infinity)= ",
" infinity, and ",
" infinity+ ",
" infinity= ",
" infinity. I think the problem is that you are imagining a fluid situation that isn't fluid. You aren't... | [
"Infinity isn't a number, therefore if you define Infinity as a set of all possible numbers, it still wouldn't contain itself."
] | [
"I'll explain what this has done another way. Two strings that are infinitely long, one red, one blue. Both wish to occupy the same space. Red string is already in that space, to create room for blue string you create a wave, and feed blue into the now empty space. The red wave will go on infinitely and you will in... |
[
"What is the slowest thing in the universe?"
] | [
false
] | Any object we perceive as stationary is still moving through the universe at vast speeds, but I would like to know what the slowest object in the universe is. | [
"Because all rest frames are equivalent, any object in its own rest frame is the slowest object in the universe."
] | [
"So does the reference frame speed (sorry if that is the wrong term) adjust by shifting time to account for my different speed in the two cases?",
"Yup. That's exactly why time dilation and length contraction happen in special relativity.",
"Basically, you have to pick between time and distance being universal ... | [
"What's a rest frame?"
] |
[
"I have some questions about the big bang"
] | [
false
] | First one: For some reason, in my head, the big bang has always been the creation of the universe, including the 'firmament' of space throughout which all matter is dispersed. I've become to suspect my intuition may be incorrect, that 'space' as we know it has 'always been here', or at least we don't know anything about its origins, and the big bang is merely the first thing we know about all the matter in the universe, not the universe itself. Which is correct, if either? Second, if my memory serves, when we look around we see the universe expanding all around us ('ignoring' for the moment that it is also accelerating). And I can't quite intuit the answer, so I have to ask: should we be seeing different motion depending on where we look, and would this be able to tell us the direction of the center of the big bang? In other words, if you are in an explosion, does the stuff on the outside of the explosion behave in any way differently than the stuff inside the explosion ? Moving slower or accelerating differently or what have you? And third: I know that dark matter and energy are still just defined as the 'unknown force' that is moving the universe in ways we can't understand, but is there even a guess as to how this could come about? Any fringe astrophysical theories that could possibly explain it? Is this 'just' a question we don't have an answer to yet, or are we still not even sure where to start looking? | [
"I'm about to give the worst introductory course on modern cosmology that the world has ever seen. I apologize with all my heart in advance for how utterly inadequate this is going to be. But maybe I can add just the tiniest bit of illumination to a dense and highly complex subject.",
"There will be simplificatio... | [
"A delight to read. Thanks for putting this together! ",
"Oh, and just so we're clear, it turns out I was right in the first place. We are talking about the origins of space it self, and not just all the 'stuff' we find in it. Space is, in fact, changing shape, and the origins of our universe are tied in with... | [
"It's both, actually. Every atom that exists, ever has existed or ever will exist congealed out of that primordial quark-gluon plasma, in one way or another."
] |
[
"The human retina has three types of color receptors: Red, Green, and Blue. How would our vision differ if you added a fourth color such as Yellow?"
] | [
false
] | null | [
"Just a comment, the so-called \"red\" cone is actually most sensitive to 560nm, which is greenish-yellow, not red. It actually is not very sensitive to red light. (It is ",
" sensitive to red light than the other 2 cone types, but it's actually just a slightly modified version of the M cone, and its peak frequen... | [
"Excellent answer. I would just like to emphasize the point you make that it's a misconception that we have \"red\" \"green\" and \"blue\" cones. Cones have sensitivities to different wavelengths. ",
"Here is a bit of an elaboration on why we need more than 1 kind of cone to see color: If you only had one kind of... | [
"Neuroscientist at Newcastle University have actually found someone with a ",
"fourth cone",
".",
"In this case I believe the cone was sensitive to wavelengths within the color spectrum - which means this individual is able to better distinguish between colors, but not see any extra colors. There is the othe... |
[
"Are some fat cells we store/burn more nutrient rich than others based on the foods we eat or are they all basically the same?"
] | [
false
] | To simplify the question I’m going to say we burn fat in layers like an onion, which I don’t think is true. If I eat nothing but an abundance of healthy balanced foods ( enough to gain a layer fat which we’ll call “good fat” ) then for a period eat nothing but Cheetos ( for my next layer of fat which we’ll call “bad fat”) Is the Cheeto layer less nutrient/ does it provide less energy than the fats made from healthy foods? Or is fat just fat and there is no good or bad? If we take away the layer burning idea and fat is burned more randomly, could it be we get little spurts of energy because our body randomly burned a bit of “good fat”? | [
"I do believe that quality of diet does change quality of fat stored (I can look up some sources), but that is different than being more \"nutritious\" fat. Fat is good or bad based on what it does hormonally. Some fat is pretty good at producing these things called inflammatory cytokines, which you don't want. ",
... | [
"So fat is released from fat cells usually by endocrine signaling which is signaling through the blood stream and thus hits most of your fat cells pretty evenly. We don't do anything like burning fat in \"layers\" although some fat stores are more responsive to releasing fat to be used for energy than others.",
"... | [
"The fat has the same amount of nutrition value whether it came from a healthy diet or unhealthy one. Usually the unhealthy diet has morw fat in general but as the other redditor said fat itself has the same nutritional value per gram.\nAlso the body has white fat and brown fat. White adipose tissue is the one that... |
[
"How can I test whether I can taste phenylthiocarbamide?"
] | [
false
] | Apparently some humans taste it as quite bitter and others taste it as nothing. What foods or things can I use to see which group I belong to? | [
"PTC paper strips are extremely cheap, and I would ask middle school/high school biology teachers if they have it since it's a common demonstration. Otherwise you can find a 100 strip vial (complete overkill) for a couple of dollars on ebay/amazon/etc. According to wiki, natural foods do not have PTC but they somet... | [
"I can find no reputable sources for cilantro containing PTC. The sharp division in different people's opinions of cilantro has led some people to think that there may be a genetic component to the way it tastes, and this hypothesis was inspired by the PTC gene. It seems that this has then mutated into a belief tha... | [
"http://www.amazon.com/PTC-TASTE-PAPER-VIAL-STRIPS/dp/B001D7FF5E/ref=sr_1_1?ie=UTF8&qid=1301242237&sr=8-1"
] |
[
"If we could intercept our first radio transmissions in space, would they still sound like they did when they left Earth?"
] | [
false
] | I thought about this question after watching posted on Reddit. It got me wondering if we (or aliens) could intercept our first radio transmissions in space, would they sound like they did when they left Earth. Would we be able to hear famous broadcasts like the Hindenburg disaster or Hitler's declaration of war? Or would the signals have dissipated over such long distances and time? Also does the same hold true for TV broadcasts? | [
"Signal-to-noise ratio is a bigger problem than the inverse square law.",
"Imagine someone is trying to whisper to you in a very crowded lunchroom. The sound is reaching you just fine, but can you tell what they're saying apart from the background? If the whispers are much, much quieter than everybody around you ... | [
"Our first radio transmissions started a bit more than 100 years ago, TV came a few decades later. That makes roughly a sphere 100 light years in radius where our signals have had enough time to travel to. This is really a very small space, not leaving the Milky Way and not reaching some of the stars we see to the ... | [
"This makes me feel like we will literally never encounter another intelligent species through transmissions alone. Am I wrong to say for example, a receiver the size of a solar system is comparable to trying to find a friend in Greater Tokyo using only morse code clicks of a pen on a table and not moving around v... |
[
"How do we derive results from a blood test?"
] | [
false
] | So I've recently had some blood tests done, and they've emailed me the results (with notes from my doctor, don't worry, I'm fine) and it got me to thinking, how do they make all these counts? Here's a couple of exerts from my full blood count: I've blacked out my results, the 'normal ranges' are the numbers in brackets, and I'm going to have to dive into Wikipedia in a moment to find out what things like HCT are, but I have a couple of questions: 1) How in the blazes do they go about counting these things? Surely it's not something as simple as a surveying square on a microscope slide? 2) How have we worked out what is considered to be within the normal range? Is this something that is frequently calibrated as time goes on? 3) When they take your blood, the phlebotomist fills a number of vials with various coloured lids and gunk already in the tube, what are these additives(?) and why do certain tests require the blood to be stored in such a way? I think that's about it, thanks for any insight! | [
"1) Most machines these days use ",
"Laser Flow Cytometry",
"Back before this technnology, we would make a smear of your blood on a slide and count the number of cell type per high power field and average it out - slightly more complicated than this but in essence this is the process.",
"2) Reference values (... | [
"Congratulations gentlemen, you passed.",
"(I run a hospital laboratory)"
] | [
"1). Red blood cell counts are commonly done with automated systems collectively called \"Flow cytometry\". However in the past (and in labs without big budgets) this was done manually with a fixed volume of blood spread over a slide. Not my ideal job but I've heard it can be very relaxing.",
"2). The normal rang... |
[
"Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Please only answer a posted question if you are an expert in the field. . In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for . If you would like to become a member of the AskScience panel, . Past AskAnythingWednesday posts . Ask away! | [
"One of the prevailing theories is that in youth, the brain recognizes (possibly even encodes into memory) most information as important because it does not know what is important and what isn't. As we mature, our brain figures out what is important and what isnt, so recognition and encoding of routine things (you... | [
"I'll try and add to this, since my background is in neuropharmacology.",
"One of the huge issues with understanding depression/anxiety/mood issues is because there are multiple brain areas that contribute to various feelings (happiness, fear, etc.) and it's some combination of the above that we don't really unde... | [
"If the teeth degrade slowly enough that the early human could survive to reproductive age and have children, then it couldn't be selected against in evolutionary terms. Also, it's likely the absence of refined sugar in the prehistoric diet meant that the teeth degraded relatively slowly. One last point is that hum... |
[
"What happens when a small black hole passes through an object?"
] | [
false
] | [deleted] | [
"For a black hole say at the super smallest size possible to be around for more than a second ( about 2.5 solar masses which is still pushing it. It is probably closer to 3 solar masses ) would still have such a strong gravitational pull it would just eat everything that it passes through probably collapsing most t... | [
"Wow, thanks for dredging through this post from two days ago! I appreciate the insight.",
"So is it fair to say then, by implications within your post, that black holes decay faster as they get less massive / smaller event horizon?"
] | [
"Much actually. Look up Hawking Radiation and it will explain a lot of the details of how but essentially it radiates energy out faster the smaller it gets. Also why it gets so much hotter too. There are almost no observed black holes that are less massive than 2.5 solar masses and those last for billions of years.... |
[
"Is there a link between sub-atomic particles and consciousness?"
] | [
false
] | null | [
"Do you have some details that would turn this into a question which is amenable to science? Consciousness is a huge mystery and is really the realm of philosophy"
] | [
"Where might we one day observe consciousness if it is indeed observable, Would it manifest as a sub-atomic particle, reside within one, or something else?"
] | [
"No idea, genuinely recommend you go have a look around ",
"r/askphilosophy"
] |
[
"Could you just by knowing the chemical composition of a compound determine its properties?"
] | [
false
] | Like if you didn’t know what water was but knew it was h2o, could you tell it’s state change points and that it’s a clear liquid etc | [
"Yes and no. Understanding the thermodynamics of a material is a very very very very difficult endeavor. In principle you could start with a model for each of the component atoms, then form a model for how they form a molecule, then form a model for how those molecules interact with each other, and finally use that... | [
"Hi pasthegucci 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 fol... | [
"An excellent question but also an extremely difficult question which may be why no one else has tried to answer it yet. I'll give it a go although I'm not the best chemist so hopefully a better one will come along and correct me.",
"The chemical composition does indicate a lot about a substances properties, part... |
[
"How does getting the flu shot work if your bodys t cells remimber the virus, why get it every year?"
] | [
false
] | So our body will remember a virus that has entered and been defeated . So then why is it we get the flu shot every year ? Do they just give you multiple flu virus strains ? Or is it a single virus strain every year. My guess is that they pick a strain that they think will be going around that year . Any answers are appreciated | [
"The flu mutates rapidly and there are many possible varieties out there. Scientists do some research and statistical guesswork about what kind of flu is likely to surge and then they make a vaccine to inure the public to it. This is also why sometimes people get massively sick despite taking their vaccine."
] | [
"I believe they pick the four most probable strains for that year, among the many flu strains that we have identified. So, while it may end up being a booster (remind your immune system of it, kind of like exercising) for one strain, the others will be novel. In general vaccines use either severely weakend or inact... | [
"Thank you for the knowledge "
] |
[
"If a boat floats in a current, under no other power, can it be turned with the rudder?"
] | [
false
] | If there was no wind, or any other force applied to the boat except for the water current could it be turned with a rudder? I feel like if the boat and the water are moving together, the rudder would do nothing, but everyone I ask disagrees. | [
"If the boat is stationary with respect to the current, no forces would act on the boat and it would not move.",
"However, real life currents are not smooth, and their energy often varies with depth and location. Depending on the design of the boat and depth of the rudder, it may be possible to direct the boat wi... | [
"Sailor here. No wind, no movement, no rudder action. Even in a current you are at the mercy of the elements."
] | [
"You are right, it would do nothing, provided the boat was not moving relative to the current."
] |
[
"What is the difference between time-dependent density functional theory and molecular dynamics? What are some limitations of each?"
] | [
false
] | What is the difference between time-dependent density functional theory (TDDFT) and molecular dynamics (MD)? What are some limitations of each? I know that TDDFT can be used to calculate excitation energies. I have heard that MD can be used to see how the atoms in a molecule move. I guess I'm just confused on the word "time" since MD depends on time as well but maybe in a different sense? | [
"Isn't Molecular Dynamics classical? It's just Newtonian particles interacting through some ad hoc classical potential that may or may not be quantum-INSPIRED. Conversely, DFT solves the many-body Schrödinger equation under the assumption of some approximated form for the quantum correlation/exchange physics."
] | [
"Neither are approaches I have any familiarity with but in a purely MD simulation there are no states. It's just a bunch of classical pinballs acting under a funny classical force. Dr. Google tells me that there IS something called \"excited state MD\" but that seems to be a hybrid approach where classical nuclei a... | [
"Yes that sounds right to me. Do you know what you would use each for though? Like would you use MD for excited state lifetimes or something? And could you use TDDFT for those as well?"
] |
[
"Do blood clots stay inside of your veins/arteries forever after they form or are they eventually absorbed back into your body?"
] | [
false
] | [deleted] | [
"There are three possible courses of action after thrombus formation.",
"1) nothing. some vessels can become chronically thrombosed.",
"2) recanalisation. basically the thrombus largely stays in place but the body reorganises it to create a new canal through the middle, essentially creating a new vessel through... | [
"Blood clots are gradually resorped by the body over time. For example, after someone gets a DVT in their leg, they are often put on blood thinners by doctors. These blood thinners don't help in resorting the clot. The body takes care of this on its own. The blood thinners are too prevent the cloud from growing fur... | [
"The tissue plasminogen activator (t-PA) is a serine protease that gets released from damaged blood vessels, their job is to catalytically activate plasmin an enzyme that will degrade the fibrin mesh in the blood clot. The degradation results in end products that are soluble."
] |
[
"Why do we have a depression in our skin above our upper lip? Does this have any significant purpose?"
] | [
false
] | null | [
"It's called the 'philtrum' and is the last bit of the face to fuse together: ",
"https://www.youtube.com/watch?v=wFY_KPFS3LA",
"Horror show starts at 00:30."
] | [
"For the record, this is exactly why some calico cats have the \"split face\" coloration, where there's a clear vertical separation of color from one side of the face to the other. "
] | [
"Thanks for the time stamp lol"
] |
[
"Is it possible for a planet to be bigger than a star?"
] | [
false
] | [deleted] | [
"In terms of volume, yes. Neutron stars and ",
"exotic stars",
" are generally smaller than planets (but heavier). In terms of mass, no. Celestial objects over 13 Jupiter masses are called stars (brown dwarfs) and celestial objects below 13 Jupiter masses are called planets (gas giants). The cut-off is somewhat... | [
"IIRC, Jupiter is about as big as a planet can be. Add more hydrogen, and it'll shrink a little bit (due to the higher gravity.) Add considerably more hydrogen (at least 12 times), and it'll undergo fusion, and thus become a star.",
"Brown dwarves are about the same size.",
"\"Real\" Sun-like stars are bigger: ... | [
"Jupiter is about as big as a planet can be",
"Almost true. The largest gas giants can be up to about twice Jupiter's diameter, especially if their atmosphere is puffed out from being close to their sun.",
"Add considerably more hydrogen (at least 12 times), and it'll undergo fusion, and thus become a star.",
... |
[
"When you have a lump of decaying material, like Radium, it doesn't all decay at once, at the same rate, right? Different atoms will \"pop\" at different times? What implications does this have?"
] | [
false
] | So I'm just imagining a lump of Radium. It's decaying, but not every atom is in lockstep with the others, right? Some atoms will decay into other things first, and some of those will be on their way to some other thing too, and so on and so on. Yes? What practical implications does that have? Is it not really a "lump of radium" but a "lump of mostly radium and smaller amounts of other things"? How do you ever really know what you've got there? | [
"So I'm just imagining a lump of Radium. It's decaying, but not every atom is in lockstep with the others, right? Some atoms will decay into other things first, and some of those will be on their way to some other thing too, and so on and so on. Yes?",
"It's equally probable for any given nucleus to decay. But th... | [
"While I can't comment on the physics, I'll comment on the implications in computing. One question that comes up here often is how random numbers are generated, and the answer is that truly random number generation requires a physical process that is random. Radioactive decay being one of those processes, a suitabl... | [
"I'm gonna chime in here (not that your explanation wasn't spot on) because I think there is some misunderstanding when it comes to decay. It's not a stuttering random effect. Yes whether a particular nucleus decays is very random but there are so many (i.e.billions and billions etc.) that it is a completely predic... |
[
"If viruses are non-living then how did they come to use RNA and DNA? Do they share a common \"ancestor\" with something that would be considered to be living?"
] | [
false
] | [deleted] | [
"The way you ask this kind of implies that DNA/RNA use was somehow ",
" by living things, but really, RNA came before both viruses and living cells, and each arose from there. So technically, yes, viruses have the same ancestor as all living things, if you consider random RNA tidbits an ancestor. But since RNA is... | [
"Another theory of the origin of the virus is that it was produced by bacteria as an alternate form of a plasmid (a kind of \"virus\" that bacteria deal with but are also symbiotic and form the closest thing to bacterial sexual reproduction)."
] | [
"the answer is: We aren't sure!",
"There are a few hypotheses about the origin of viruses. The genes of many viruses seem to share things in common with genes in organisms. One hypothesis out there is that what would eventually become viruses first started out as portions of cellular DNA or RNA that then became i... |
[
"Where and why are there gaps in the fossil record?"
] | [
false
] | The main argument I hear people use against evolution is the presence of gaps in the fossil record. I never have an argument back, though I assume not everything can be preserved, but I would like to know this. Thanks! | [
"From ",
"http://evolution.berkeley.edu/evosite/misconceps/IICgaps.shtml",
"Response: The fact that some transitional fossils are not preserved does not disprove evolution. Evolutionary biologists do not expect that all transitional forms will be found and realize that many species leave no fossils at all. Lots... | [
"Some excellent answers here dealing with the fact species are continuously varying - the fact is species are a human attempt to classify things that are only as good as the data available.",
"To deal with the reason why there are gaps in the fossil record - fossilisation is an incredibly rare occurance. The anim... | [
"also, consider this: Scientist has 2 fossils A and C; creationist says 'aah but theres a gap'...later scientists find fossil B (which goes in the gap)....but creationist says 'aah but now you have 2 gaps'... ",
"and so it goes on: for the creationist, more evidence = more gaps. Doesnt really work as a logical a... |
[
"How do the \"Miracle Berry\" tablets work?"
] | [
false
] | I've seen these Miracle Berry tablets that claim to turn sour things sweet, and on the they claim "The truth is, science doesn't completely know (it has something to do with the protein miraculin that bonds to your taste buds, but the exact cause is still a mystery). But the berries work, and it's a miracle." I don't believe them. How do they work? | [
", such as HCl, oxalic acid, lactic acid, formic acid, acetic acid and citric acid; the sweetening effect is ",
" (Kurihara and Beidler 1969). The sweetening effect of a miraculin solution reaches its ",
" (Kurihara and Beidler 1969). A ",
". The taste-modifying effect of miraculin can be ",
", although it ... | [
"Found a nice explanation \n",
"Here",
" and ",
"Here",
" that I could understand!"
] | [
"Yeah, not only do they work but are an effective diet aid as you can satisfy a sweet tooth without so much sugar."
] |
[
"Do women have appetite changes to go with monthly cycles (excluding the obvious period cravings)?"
] | [
false
] | Half the month I have absolutely no appetite and barely eat. The other half of the month I am ravenously hungry. Is this related to me being a woman, or is this just a human thing? | [
"People are only just starting to track this stuff & figure out how diff hormones affect different people, so I don’t think anyone really knows the answer to your question.",
"but it sounds like follicular phase vs luteal phase to me!"
] | [
"Thank you! I’ll look that up 😊"
] | [
"one friend of mine has figured stuff out by tracking it herself. always writing down what day menstruation started (full flow), & writing down extreme moods.",
"Look up how long the luteal phase is (it’s pretty constant in everyone). One way to thin k of it is we have 2 different normal hormone balances, lutea... |
[
"If we have 2 identical particles and launch them at the same time in different directions and then we measure first particle momentum and the other position wouldn't we find the exact momentum and location of any of the particles ?"
] | [
false
] | null | [
"No, because the particles will form an ",
"entangled system",
". The two particles are in quantum superposition and measuring the momentum of one necessarily increases the uncertainty in the position of both of them, since otherwise this kind of system would be a neat shortcut around the uncertainty principle.... | [
"Entanglement doesn't violate relativity because no information is exchanged in this so called speed you are referencing. Relativity limits the speed that ",
" can propagate at to c."
] | [
"I see that this occur at least 10,000 times faster than the speed of light but general relativity theory limit it at c, how is this possible? "
] |
[
"Is the universe a perpetual motion machine?"
] | [
false
] | [deleted] | [
"I'm not clear what you mean by perpetual motion machine.",
"Yes, the universe is a closed system, so any energy that it has now won't be going anywhere.",
"The second law of thermodynamics is still in effect, however, so entropy will constantly increase until there is no longer any \"useful energy.\" This is ... | [
"Yes, the universe is a closed system, so any energy that it has now won't be going anywhere.",
"Not really. Energy is only conserved locally. The universe can't be described in terms of a single instantaneous reference frame for more than, well, one instant. So you can't really talk about energy conservation on ... | [
"Hrmph. Reddit seems to have eaten my first reply.",
"Energy isn't Lorentz-invariant. Change reference frames, and the total energy of a system changes. Our universe isn't time-translation invariant. You can only ",
" that it is on small scales. Hence, energy conservation is purely a local phenomenon. It's not ... |
[
"What would happen if you dove in a pool while covered with a hydrophobic material?"
] | [
false
] | As the title says. Lets say you get in a skin tight suit or something similar, sprayed yourself with a hydrophobic material (like shown in this video ) and dove into a swimming pool? Would it make you float? Would you glide through the water? | [
"Likely not much would be different. Let's say you wore a teflon suit, the water would still wet to the teflon suit, as a water-teflon interface is lower energy than a teflon-air interface PLUS a water-air interface. To demonstrate this at home, put a drop of water on a (unheated) teflon cooking pan. The water wets... | [
"There would be a thin layer of air surrounding you, as shown in ",
"this video",
" of hydrophobic sand.",
"EDIT: Stop upvoting me and listen to cosmicosmo4. I don't know what I'm talking about and he does. "
] | [
"They become very fast, and get used by all top competitive swimmers for a while and then get banned from formal competition. High end swim suits use patterns of hydrophobic and normal material (mainly the \"FastSkin\") and were banned about 2 years ago.",
"http://en.wikipedia.org/wiki/LZR_Racer"
] |
[
"Physics - Nuclear Fusion"
] | [
false
] | I was trying my best to explain nuclear fusion to somebody today and I came to one important question: If you perform nuclear fusion with, let's say, Deuterium and Tritium, having Helium 4 and a Neutron as a result, with incredible amounts of energy of course, where do the matter destroyed by the fusion go? Wikipedia says that the Neutron is "freed" in the reaction, but in my opinion you actually reduced some matter to an energy status. Can matter and energy be the same thing, something we would call "being" generally speaking? I understand that the sun takes hydrogen and makes helium and so on. Could we say then that the end of the universe will come when all matter have been fusionned in very heavy atoms, freeing energy but emptying the world at the same time? | [
"where do the matter destroyed by the fusion go?",
"What destroyed matter? You start with a Deuterium atom (p + n) and a Tritium atom (p + 2n) and end with an alpha particle (2p + 2n) and a free neutron (n): two protons and three neutrons go in; two protons and three neutrons come out.",
"Wikipedia says that th... | [
"Mass and energy are the same thing. Think of rest mass as energy that is \"trapped\" in one place. Some of this \"trapped\" energy is freed in the D-T fusion reaction."
] | [
"E=mc",
"This is why nuclear fission reactions are so violent. Mass can be converted to energy and when released that conversion scales the mass by the speed of light squared. The same occurs in fusion. An interesting thing about atoms is that the mass of the whole does not equal the mass of its parts. This diffe... |
[
"What would happen if a human body stops producing hormones altogether?"
] | [
false
] | null | [
"People often forget that insulin is a hormone. Sorry to burst the bubble, but it is very simple. You would go into Diabetic Ketoacidosis, much like a type 1 diabetic, fall into a coma and die within the first 24-48 hours. ",
"You may have some competition is ADH (Anti-diuretic hormone) which prevents water from ... | [
"All the above is true. However these hormones act slower than cathecholamines such as norepinephrine and dopamine. Without these hormones you would have no blood pressure and go into shock, then multi organ failure quickly resulting in death. "
] | [
"There is no reuptake of acetylcholine, it's all catabolised by acetylcholinesterase. I'm quite sure death would be near-instantaneous if ",
" hormone synthesis were to suddenly halt."
] |
[
"I can't seem to understand what a virtual image is in optics. Secondly, is a rainbow an example of a virtual image?"
] | [
false
] | null | [
"When you look at something, your eyes see and your brain interprets rays of light diverging from individual points of the object. This is called image formation.",
"When you look through a magnifying glass at something, you still see rays of light that ",
" emanating from a common point, but those rays of lig... | [
"So, to add to this, yes, a rainbow is a virtual image.",
"In this picture",
" the rainbow will appear to be coming from the top right."
] | [
"Easy determinant is whether the image can be produced on a screen or not - real images will, virtual images won't. Reals are produced by light rays that actually converge to a point (which is where we perceive that point to be), whereas virtuals only appear to converge at a point, but actually originated from some... |
[
"Why did old CRT TVs get some discoloration when you hold a magnet up to them?"
] | [
false
] | And why dont modern led tvs do that. | [
"The pixels of a CRT are made from a phosphorescent material that emits light when hit by electrons. To create the picture, a modulated electron beam is swept over the screen to selectively light up the pixels you want to light up. For each point, you actually have three pixels for the elementary colours. If you pu... | [
"In a modern TV, the pixels are actively light emitting semiconductors",
"This is only true of OLED and Plasma displays. In LCD TVs, each pixel does not emit discrete light, rather it blocks or passes light from a single large uniform source behind a colour filter."
] | [
"The electron beam was definitely being pushed around as others have suggested.",
"I interpret your question of 'discoloration' to include long-term changes to the picture (as opposed to just 'distortion'); colors being thrown off or \"color halos\".",
"The reason this happens is on some models of television th... |
[
"What are a cat's whiskers for and how do they work?"
] | [
false
] | null | [
"They are used by cats to help navigate, especially in the dark. They are very sensitive to being bumped, so as a cat walks forward in darkness, any time the whiskers get bumped, the cat knows they're about to run into something.",
"The tips of their whiskers are usually about the width of their body. This helps ... | [
"Couple of questions here: ",
"If a cat were to put on a lot of weight and start to 'bulge', would the whiskers grow to compensate? ",
"Do the whiskers account for a cat being able to compress somewhat?",
"\nI.e. it's ribcage can be smushed so the cat is thinner, fat can roll around the bars or whatever it ... | [
"\"If a cat were to put on a lot of weight and start to 'bulge', would the whiskers grow to compensate?\"",
"No. Source: my cat Jojo, currently 22lbs and on a diet."
] |
[
"What are the issues with using tritium as fuel for a radioisotope photoelectric generator?"
] | [
false
] | null | [
"And many of them have ",
"CURIEs",
" of tritium in them. I have some self glowing exit signs that are only dimmly lit in the dark but were initially filled with 20 Curies of tritium!"
] | [
"Tritium has a fairly long half-life so it doesn't emit radiation rapidly. Because it only emits beta particles rather than photons directly, it also requires a second compound to allow photons to be generated - this isn't very efficient process.",
"Have you seen a tritium light source? They aren't very bright ev... | [
"I don't mean for conventional use, I thought I saw NASA used tritium for a RPG on a probe."
] |
[
"How does our brain wake itself up?"
] | [
false
] | null | [
"It's all a balancing act. The hypothalamus--the trapese artist of the brain--has two hubs decidated to sleep and wakefulness. The ventrolateral preoptic area (",
") promotes sleep. The lateral hypothalamic area and the posterior hypothalamus (",
") promotes wakefulness.",
"",
"",
"The LHA/PH works in c... | [
"Absolutely fascinating. Thank you for taking the time to so clearly articulate this complex system. Greatly appreciated."
] | [
"From an external stimuli perspective I believe it is light that initiates it (naturally). However, loud noises often do the trick.",
"From a biochemical perspective I recall that adenosine is the neuromodulator responsible for regulating sleep cycles. How it does that I'm not 100% on but that gives you a startin... |
[
"When was the sonic boom discovered? What was the general population's reaction?"
] | [
false
] | null | [
"By going faster than the speed of sound.",
"https://en.wikipedia.org/wiki/Whipcracking#Physics"
] | [
"Lashes of whips can create sonic booms. So... very long ago? At that time there was no good explanation for it of course.",
"Edit: Wrong word."
] | [
"I bet most people assumed the crack of a whip was from the tip hitting itself rather than breaking the sound barrier."
] |
[
"Would it be possible to make contact lenses that have the same effect as 3D glasses?"
] | [
false
] | Has this been done? Would it be safe? Is it possible? Would it work? | [
"I'm no 3D expert but my understanding is that all you need are 2 different \"filters\", one for each eye. Then you display 2 slightly different images, each one being able to be viewed by each eye's filter. ",
"So for example back in the day when you had to use those red and blue glasses, there was an image disp... | [
"Use polarized filters (one vertical, one horizontal for ex) and you have the same idea as passive modern 3d glasses."
] | [
"Using just vertically and horizontally polarized filters leads to the problem of bleed through when you tilt your head. (It is possible to get the lenses oriented the right way in the same way that contact lenses can maintain their orientation for astigmatism.) The circular polarizations used by RealD 3D don't h... |
[
"If hand sanitizer kills 99.99% of germs, then won't the surviving 0.01% make hand sanitizer resistant strains?"
] | [
false
] | null | [
"Most hand sanitizers use alcohol, which kills indiscriminately. It would kill us if we didn't have livers to filter it, and in high enough doses will kill anyway. Some germs survive due to randomly being out of contact, in nooks and crannies and such, not due to any mechanism that might be selected for."
] | [
"Let's say you throw 1000 humans into a volcano. One of them happens to land on a ledge inside the volcano and escapes. If he has kids, they will not be volcano resistant."
] | [
"Sanitizers almost always use alcohol, which bacterial cells don’t really have any cellular means of developing resistance against. You may as well worry about developing resistance to having a nuke dropped directly on your face. Alcohol essentially saps bacterial cells of all moisture instantaneously, and to com... |
[
"What happens to the mass of a burned object?"
] | [
false
] | [deleted] | [
"a completely isolated system will experience no loss of mass. If it is a realistic system, there will be a slight conversion of mass into energy, but the amount will be incredibly tiny. Say you release 10 kJ of heat, E=mc",
" so you take 10/(300000000)",
" g of mass lost. The heat would actually be much gre... | [
"The average heat of combustion of wood is about 15MJ/kg, So 10kg would create 150MJ of heat. By E=mc",
" , m=150,000,000/300,000,000",
" =(5/3)x10",
" kg. That'll be the loss in mass, roughly."
] | [
"g or kg? You guys keep changing it."
] |
[
"I was musing yesterday and caused a debate I hope /r/askscience can help me with. Can Usain Bolt, out accelerate a car?"
] | [
false
] | [deleted] | [
"For Bolt to beat a car to 100 meters that car has got to be about dead. Bolt's best time to 100 meters is 9.58 seconds. That's an average speed of 23.3 MPH, which is obviously very impressive. But any car that's only managed to average 23 MPH after almost 10 seconds of acceleration is in very bad shape."
] | [
"Based on 20m splits from ",
"Sports Scientists",
" His maximal acceleration is the first 20 meters, from 0-25km/h in 2.89 seconds. This works out to ~2.4m/s",
" ",
"Based on ",
"0-60 Times",
" the acceleration of a 1985 civic is 0-96kmh in 11.8 seconds. That works out to 2.25 m/s",
" ",
"So yes. At... | [
"It wouldn't have to be a competent driver. You could forget the handbrake and leave the car in first gear, a decent sports car will still win. ",
"Car: Lotus Elise 2011",
"\nSome numbers:",
"\n0-97km/h: 4.4 seconds",
"\nAverage Acceleration: 6.123 m/s",
" over the first 4.4 seconds",
"\nDistance trav... |
[
"Why do pathogens transmitted with a vector often cause more severe diseases than those transmitted by direct contact?"
] | [
false
] | null | [
"Okay nevermind I found it!\nSince vectors can transmit the disease even if the diseased is dead, it doesn't matter if the pathogen multiply quickly, hence a high death-rate. But other diseases which need to be transmitted from different carriers can't multiply as quickly because then they'll kill their first carri... | [
"I don't think that's right. Ebola, not vector-transmitted, can transmit disease up to five days after death. Myxoma virus of rabbit, transmitted by sand-fleas in Australia, wasn't transmitted after death because the vectors didn't feed on dead bodies. I don't believe that mosquitoes will bite dead bodies, eithe... | [
"I found my answer in a biology book which hopefully should be correct. They presented a chart that showed overall death-rates among vector-transmitted diseases aswell as non vector-transmitted diseases, where it was higher in vector-transmitted ones. The chart didn't have a source though, but I'll trust it.",
"T... |
[
"What is the physiological/biological/psychological response to self harm (i.e. cutting)"
] | [
false
] | I am working on licensure for being a counselor. Often clients who engage in self harm, such as cutting, say that it is self-medicating. What I want to know is what causes them to feel medicated? I know that psychology plays a role in this but it cannot only be psychological. These clients also often express that the cuts or other forms of self harm do not actually cause physical pain. What is going on there? TLDR: Soon to be LPC, What is the physiological/biological.psychological response to self harm? | [
"Injuries trigger the release of endorphins, which in the case of normal injury is to cause an analgesic effect. In the case of cutting, they're going for the \"side effect\" of endorphin release, which is to get a sense of euphoria. In basic terms, cutting is like taking a drug, without the physical addictive prop... | [
"Awesome! Thanks. Do you have any journal article references for this? I would love to read some research on it. APA or MLA citation or link is fine."
] | [
"Alright. I've tried like hell to find you free copies of these, but failed. You'll have to get the journals:",
"Plasma B-endorphin levels in patients with self-injurious behavior and stereotypy - American Journal on Mental Retardation, v95 n1 p84-92 Jul 1990",
"Relationship between release of beta-endorphin, c... |
[
"Why is that when you get a cut (a big cut, not paper cut), and water gets poured on it, it burns?"
] | [
false
] | null | [
"When you have a cut, tissue is exposed that does not have the protective hydrophobic layer of skin. ",
"Water is hypotonic and when those exposed tissues are exposed the cells swell and it causes irritation. That's why 0.9% NaCl is often used to irrigate wounds because it is isotonic and does not cause the cells... | [
"So to wash a minor scrape or wound without access to saline, would it be preferable to use a mix of 9g/liter of table salt and filtered water over just using water from the tap?"
] | [
"depends on whether 0.9% by volume or weight"
] |
[
"Dear Scientists, How hard is it to synthesis Diesel or Petrol or other fuels obtain by crude oil?"
] | [
false
] | null | [
"Not hard, just not worth it while there's cheap oil to burn.",
"Basically, you use a ",
"gasifier",
" to generate a mixture of H2 and CO gasses, called \"synthesis gas\". This is basically done by burning a chunk of carbon (which can come from coal or biomass) in an oxygen-starved atmosphere, and then passin... | [
"Thanks and appreciate your reply"
] | [
"There was a ",
"plant",
" that up to a few years ago was cranking out crude oil from turkey offal. ",
"But it ",
"shut down",
" due to financial problems."
] |
[
"What causes the two big population spikes in China's population pyramid?"
] | [
false
] | China's population pyramid is unique, as it has two large groups of people at the age 25-35 and 45-55. I would guess this has something to do with their one-child policy and their explosive population growth since the 1900s. but i haven't found any sources on this. Could anyone help me out? | [
"I believe the first \"spike\" was due to (a) the great leap forward in the early 1960s which killed a lot of people, and (b) decreased birth rates starting around 1970 due to a two-child policy and then one-child policy. Basically, starting in the mid 1960s, birth rates dropped. Consider also decreases in mortal... | [
"Not an expert, but are you sure it's two spikes and not one dip for ages 35-45? Also what year was the population pyramid you're looking at published in?",
"Because if you're thinking about China 45 years ago, you're talking about the middle of the Cultural Revolution. If your pyramid is a few years old, the 35-... | [
"FWIW, I found a chart of birth rate in China ",
"here",
" showing birth rate peaks around 1963 and 1987. ",
"And the Chinese population pyramid for 2016 ",
"here",
"."
] |
[
"Question about specimens suspended in blocks of glass or plastic, and how they're made."
] | [
false
] | At my elementary school library, there were a bunch of specimens - mostly of insects, spiders, scorpions, seahorses, and coral - that were perfectly suspended in glass. At least, I'm fairly certain it was glass. My question is, how can something organic be encased in glass like that, and positioned so perfectly? Wouldn't the heat from the glass-making process utterly destroy them? Just how are specimens like this made? Even if it was acrylic or some kind of plastic, wouldn't they still have to be made at temperatures too hot for delicate specimens to remain intact? | [
"It is likely encased in plastic. When making plastic, you mix together chemicals to form a polymer, but not necessarily at high temperature (usually 100 degrees C). You can then place the specimen in the liquid plastic and cool it.",
"This is a common lab done in undergraduate organic chem courses."
] | [
"Thanks. Exactly what I wanted to know. "
] | [
"If you're interested in this kind of thing, there's a subreddit called ",
"How It's Made",
"."
] |
[
"Are terrestrials and gas giants the only two possible types of planet?"
] | [
false
] | According to Wikipedia, the planets in our Solar System fall into two categories: Terrestrials (Earth-like planets primarily made of rock, sometimes with an atmosphere), and gas giants. Are there any scientific theories regarding other types of planets that could exist, or does the scientific community currently believe those are the only two possible types of planet? | [
"There's actually an extensive list of planetary types on Wikipedia: ",
"http://en.wikipedia.org/wiki/List_of_planet_types",
" that said some like \"rogue planet\" could be a \"rogue terrestrial planet.\" However following the type theme of terrestrial and gas giant there are also ice giants, iron planets, ocea... | [
"That list doesn't really address the question.",
"It's just a flat collection of groups with no indication of which categories are mutually exclusive and which are not. For instance, ",
", ",
", and ",
" are all on the list. We know of ",
" of either of the latter classes, and the ",
" class doesn't ... | [
"From what is known about Gliese 436b, the ocean extends so far down so as to substantiate a good percentage of the total planetary radius. From these theoretical depths, liquid water would be under such a tremendous amount of pressure that completely exotic forms of ice would form such as Ice VII. However, as far ... |
[
"Can somebody explain why radio waves can go through matter (i.e. walls), but visible light -which has more energy- cant?"
] | [
false
] | As you may know, my physics knowledge is limited, but i've wondered this for a while. It goes hand in hand with me trying to disprove people who keep saying radio waves from cellphones can cause cancer... to which I always reply it doesn't make sense. | [
"Essentially yes, although I want to be sure I answer you accurately so I'm going to go a little into it, to make sure I understand your question.",
"So as I'm sure you know the eltro-magnetic spectrum, such as Radio Waves, Visible light, Ultraviolet, X-Rays and Gamma rays are all made up of photons. The reason t... | [
"You will still see the box because it absorbs all visible wavelengths but blue. Most ordinary materials eventually absorb or reflect all visible wavelengths. The only ones that don't, require these massive excitation energies.",
"Remember all of what we can see is a combination between absorption and reflection.... | [
"I find this explanation specious. Cell phones are related to cancer formation - specifically, people who develop brain tumors are predisposed to develop them on the side of the head that they use to talk into their cell phones. ",
"http://journals.lww.com/epidem/Abstract/2004/11000/Mobile_Phone_Use_and_the_Ris... |
[
"Would it be possible for humans to drink seawater?"
] | [
false
] | I just read this article " " saying how cats can drink seawater, and my thoughts were that we humans are seeing a future water shortage. Would it not be better for us to instead of looking for a way to remove the salt from the water find a way for us to drink the seawater like cats can? Perhaps through future genetic manipulation? | [
"The main problem with drinking seawater is that it actually dehydrates you. Your body senses an overload of salt in the intestines and secretes water into the lumen to lower the concentration gradient. The result is actually a net water loss, rather than a water gain."
] | [
"When I read the link that i had in the text it says that the cats kidneys I believe it was is able to process the water so its drinkable.\nWould it not be more simple to try to achoeve something like this instead of trying to find a energy efficient way of separating the salt from the water?"
] | [
"I feel uniquely equipped to answer this question. I'm a vet student going through diseases of the kidney right now. One of the main differences between the cat and human kidney is that the cat kidney is unilobar where the human kidney is multi-lobar. Part of the physiologic differences that exist as a result of th... |
[
"[Physics] How did physicists prove that gravitational waves do not travel faster than the speed of light?"
] | [
false
] | null | [
"Physicists have known for a long time that gravity \"moves\" at the speed of light. According to Einstein's theory of relativity, nothing can ever move faster than c, not even gravity.",
"Last year, physicists observed a neutron star collision that caused a gravitational wave and a burst of gamma rays to be dete... | [
"Additionally, the gravitational wave was detected at two locations with a time interval between equal to distance/c. "
] | [
"If some signal carrying information is sent faster than light, you can choose a reference frame in which its effect precedes its cause, allowing you to affect the past. "
] |
[
"Can someone review this video showing the solar system moving through space, is this a correct approximation or false visualization and why?"
] | [
false
] | null | [
"Phil Plait gave a very good commentary on this video.",
"While it's an amusing attempt at depicting the motion of the solar system in the galaxy, it gets a lot of stuff pretty wrong. "
] | [
"/u/VeryLittle",
" already answered this but I want to reinforce the point that the video, while visually appealing, is not a helpful portrayal of the solar system. At the very beginning it commits the unforgiveable offense of claiming that the Sun isn't the center of the solar system. One of the major premises o... | [
"... The ecliptic plane is inclined about 60° from the galactic plane (and not 90°) like in the video. We are moving through the galaxy basically following the galactic plane.",
"The rest of the video about life and spiral mumbo jumbo is precisely that: Mumbo jumbo pseudo-scientific woo.",
"EDIT: I did not look... |
[
"I live in Florida, will I be able to witness the upcoming lunar eclipse?"
] | [
false
] | [deleted] | [
"This should help",
"http://eclipsegeeks.com/images/NASA%2010%20dec%202011%20TLE%20eclipse%20geeks.jpg",
"Short answer - not really"
] | [
"The ",
"wikipedia",
" page may give you more details. It looks like the moon will set in the eastern time zone before the partial eclipse begins, so you will not be able to view the eclipse in Florida."
] | [
"Looks like not :("
] |
[
"What purpose do tails serve on mammals?"
] | [
false
] | Same with lizards and other reptiles, is there an evolutionary advantage? | [
"For balance and stability. Both by moving laterally to increase stability and decrease \"wobble\" while running, and in some cases to adjust the center of mass to a position where it may be more easily manipulated.",
"In addition to that, some animals (like elephants, rhinos, horses, and cows) use them to keep i... | [
"How would a turtles or rats tail aid in stability?"
] | [
"Rats use them to balance, like when they run along a thin rope. If they fall right, their tail goes left, keeping them balanced. Like the long pole that tightrope walkers utilize, but evolutionarily developed rather than implemented as a deliberate tool."
] |
[
"Do kidneys adapt to whether/regions with higher temperature?"
] | [
false
] | It is known that after some time in a weather with much higher temperature than we are used to, we adapt by having changes in our sweating and metabolism. I do not know whether our kidneys also adapt in the long term by, for example, reabsorbing more water and producing urine with a higher concentration of solutes. | [
"A simple answer to your question is yes they do, but the adaptation is not as simple as x degrees increase in temperature so y amount of change in reabsorption. ",
"Our metabolism adapts to maintain body temperature at about 98 F which is what the kidneys will be exposed to, but what does change is water level i... | [
"Thanks so much for your response. I deal with population data of some sort and have noticed that the longer (years) some people are working at a very hot place (not born there), the more urine indicators of dehydration with no signs of kidney damage."
] | [
"It is very interesting you mention that, we do know for a fact that isolated kidneys, slices or nephrons have a higher capacity to reabsorb salts compared to what is noticed in vivo. Which cna explain why you don't see kidney damage even though there are doing more."
] |
[
"Can you eventually die from lack of sleep?"
] | [
false
] | null | [
"To add to this, there is a prion disease called Fatal Insomnia which leads to total sleep depravation and death. This is the only time I’ve heard of sleep deprivation becoming fatal. I imagine that those without the disease will end up sleeping at some point whether they like it or not."
] | [
"While no human has been attributed sleep deprivation to a cause of death, the university of Chicago did a study on rats, after 32 days of total sleep deprivation all the rats were dead. They didn't all agree of a specific reason they were dead, other then whatever the actual reason was, it's due to the lack of sle... | [
"I have never read of a cause of death being lack of sleep in any publication. However, sleep deprivation can cause severe impairment in the individual, leading to drastically heightened risk when , for example, driving a car.",
"Sleep deprivation, given enough time, will cause psychosis, but it will not cause di... |
[
"How do we know the age of light that we receive on Earth?"
] | [
false
] | Meaning, how do we know that certain objects are x distance away and certain objects are y distance away? How have we measured the furthest objects away to be 13.7 (I think) billion light-years away? I understand that all objects outside of our local cluster of galaxies are red-shifted. Is it some kind of interval measurement between the frequency of the wavelengths? | [
"A photon doesn't age or degrade in any way, so the age of it must be measured by figuring out the distance it's travelled. ",
"Distance of stars can be measured in a couple of ways. One uses triangulation. We know the diameter of our orbit, so if we are to measure the angle of a star when we are at the aphelio... | [
"I believe the triangulation method can only provide accurate distances for stars within 500 light years or so. It's been quite a few years since Astrophysics class. ",
"After some quick rough calculations using the built in calculator on windows, since I don't have another one available atm, I got something cl... | [
"3/10,000th's of a ",
". 2pi radians = 360 degrees. Also helpful is knowing that a parsec is the distance at which 1 AU subtends 1 arcsecond (it's short for \"parallax second of arc\"). A star 3 pc away has a parallax of 1/3 of an arcsecond ~ 1/10,000th of a degree. We can now measure parallaxes of a couple t... |
[
"What determines the rate at which lightning moves across the sky?"
] | [
false
] | There's a pretty good thunderstorm going on outside my window, and it occurs to me that I can watch lightning progress across the sky - meaning it's 'traveling' at substantially less than the speed of light. It was my understanding that electrical charges travel at something approaching c. So, given that's clearly not the case, what determines the rate of propagation of a lightning bolt? | [
"Here is an interest slow motion video of lightning (with time display at the bottom):",
"http://www.youtube.com/watch?v=-bvmEYxEYiA",
"You can see a lightning has two steps, first an ionized air path is created, this is the slow part, because air takes time to get ionized, you can see one took over 50 millisec... | [
"Very neat. I suspected it had to do with the ionization step, but I (incorrectly, I guess) assumed that the plasma would not luminesce until the discharge phase, which should be (relatively) instantaneous. I guess what I am seeing is the electric charge slowly burning it's way through the cold air in the cloud."... | [
"The speed at which light propagates through transparent materials, such as glass or air, is less than c. The ratio between c and the speed v at which light travels in a material is called the refractive index n of the material (n = c / v). For example, for visible light the refractive index of glass is typically a... |
[
"Do we know where in the universe the big bang occured?"
] | [
false
] | null | [
"Everywhere"
] | [
"When I picture a bang, it happens at a central point and matter moves outwards. How can it happen everywhere?"
] | [
"Because the Big Bang is just a name, a purposefully derisive one. It was nothing like a chemical explosion"
] |
[
"How are sea turtles so good at holding their breath?"
] | [
false
] | Apparently sea turtles can hold their breath for up to seven hours while they're sleeping. How the heck can they do this?? | [
"Here's a good post: ",
"http://www.emperordivers.com/blog/2009/07/how-air-breathing-diving-animals-hold-their-breath.html",
"TLDR: basically, air-breathing animals that dive have an extra protein that's like hemoglobin (which carries oxygen throughout your blood) called myoglobin. What happens is animals breat... | [
"As in diving mammals and birds, several factors influence this capacity: ",
"some sea turtles, such as leather backs, can store large quantities of oxygen in their blood and in their muscles, bound to hemoglobin and myoglobin, respectively. Shallow water species however don't show this specialisation.",
"the h... | [
"To add to the below: reptiles have much lower metabolic rates than mammals, since they're not maintaining a body temperature. This is especially true at low temperatures. Snapping turtles winter in the mud below ponds, not breathing for months."
] |
[
"Question about the Schrodinger’s Cat thought experiment"
] | [
false
] | From Wikipedia: Schrödinger's cat: a cat, a flask of poison, and a radioactive source are placed in a sealed box. If an internal monitor detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison that kills the cat. There is a supposed 50% chance of this happening. The Copenhagen interpretation of quantum mechanics implies that after a while, the cat is simultaneously alive and dead. Yet, when one looks in the box, one sees the cat either alive or dead, not both alive and dead. This poses the question of when exactly quantum superposition ends and reality collapses into one possibility or the other. My question is this: If the only way to tie a quantum phenomenon to larger world of classical mechanics is to utilize some sort of device (in this particular iteration of the famous though experiment, a radiation monitor) to detect the quantum phenomenon, then why would any interpretation of QM (outside of the consciousness-causes-collapse interpretation) imply that the cat would be alive and dead at the same time? Even under the Copenhagen interpretation, wouldn’t the measurement of the radiation cause the quantum eigenstates to collapse into a single state? It seems to me that it would not be possible to tie a quantum phenomenon to larger world without first making a measurement, causing the wave function to collapse. Can anyone tell me what I am missing here? | [
"The problem is that Schrodinger's cat is a terrible way to illustrate quantum mechanics. All it's trying to demonstrate is that as long as you can not observe something, the particles exist in all possible states. You have to act on a particle in some way to observe it (shoot electrons at it or something), and whe... | [
"He thought it was ridiculous."
] | [
"Schrodingers cat was meant to illustrate how unphysical that interpretation is not as an actual thought experiment.",
"It is entirely a byproduct of the probabilistic nature of QM. If you have a particle (or a cat) you must account for the all possible outcomes of the solution if you have not measured the solut... |
[
"If you lived in a cold climate, had a heated home, but instead of walls you had lines of small stirling engines, could the difference in temperature power the heater and keep you warm?"
] | [
false
] | Of course i don't mean there to be , it would have to be a sealed home. I guess the way to store and convert the energy to the heater would be the harder part, but still, how viable would this be? I realize this is absurd, but i'm wondering if this could work considering one could have a large difference in temperature (IE if it's -10C outside, and inside its +20C). And of course you'd need something to start up the heater and get it going. Feel free to point out any misconceptions about stirling engines i may have made, thank you! | [
"Stirling heat engines (or any heat engine) will do exactly what you ",
" want: transfer the thermal energy outside. ",
"In the process, they will create a relatively small amount of energy (1-263/293 = 10% at most) through work that you could turn back into thermal energy inside, but it won't come close to the... | [
"The energy from your heater is used to power the engines which in turn power the heater.",
"This sort of self-supporting energy source doesn't work, it would otherwise be free energy.",
"What you ",
" do is put a little electric motor to drive something like a sterling engine which will then be acting as a "... | [
"If the inside of the house started out hot with cold outside of course the engines would run, but they would generate much less energy to run the heater than the house would lose through the engines running."
] |
[
"What's the smallest celestial body that could maintain a satellite in orbit?"
] | [
false
] | Could we put a satellite in orbit around, say, the moon? | [
"Anything in theory could have a moon around it thats smaller. \nIn ",
"universe sandbox",
" for instance they male a tennis ball orbit a bowling ball (which should work if nothing more massive is around) "
] | [
"That's fine, we've had plenty of satellites orbiting the moon."
] | [
"This, it depends on what else is nearby. There could be a tiny pebble orbiting a small asteroid, but as soon as it gets near another asteroid, the orbit will be perturbed."
] |
[
"Why is it that your eyes can \"pan\" smoothly back and forth when following a moving object, but are more \"stuttery\" when you try to do the same without a moving object?"
] | [
false
] | What I'm observing is that when I move my finger back and forth in front of my face, my eyes seem to follow it smoothly. But when I stare at the wall and move my eyes back and forth without focusing on anything in particular, I find that my gaze "jumps" at certain intervals. Sorry I can't articulate it any better than that, but I hope that makes sense to somebody. | [
"I don't think he is describing saccades. He means when his eyes track an object they move smoothly, but if he attempts to move his eyes smoothly ",
" following an object he can't do it. In any case, saccades movement is too small to be 'visible'. "
] | [
"I don't think he is describing saccades. He means when his eyes track an object they move smoothly, but if he attempts to move his eyes smoothly ",
" following an object he can't do it. In any case, saccades movement is too small to be 'visible'. "
] | [
"Not sure what the focus of your question is (no pun intended!), but this might be of interest: ",
"http://en.wikipedia.org/wiki/Smooth_pursuit#Smooth_pursuit_in_the_absence_of_a_visual_target",
"And ",
"here's a non-paywall version of the paper cited for \"Performing smooth pursuit without a moving visual st... |
[
"Why do we use the word 'volume' to refer to how loud something is, when volume is typically a measurement of physical size?"
] | [
false
] | null | [
"This is an etymological question and the short etymological answer is: Etymologically, they mean the same thing. ",
"Here's a link to ",
"'s etymology dictionary entry.",
" Let me sum up the history of the word:",
"The Latin word ",
" means \"to turn\" or \"to wind\" (you see this in \"-volve\" words lik... | [
"For those interested in this post and answer, I also recommend ",
"/r/etymology",
" as a fun sub."
] | [
"I'm an acoustician and this is the correct answer. Contrary to the other answers, there's no physical reason to call the loudness \"volume\". If that knob had been named to reflect the science and engineering behind it, it would be called \"gain\" to reflect the gain of the audio amp feeding the speakers.",
"Y... |
[
"How close would you have to be to the Sun to be warmed by its heat without an atmosphere?"
] | [
false
] | As I understand it, (of course I could just be wrong) if you leave the atmosphere towards the sun the temperature would drop to absolute zero. Inside the atmosphere particles can collect the Sun's energy and therefore some amount of heat exists, even if it's very little high up where the air has very low density. So how close would you have to get to the Sun to be warmed by its rays directly, and enough to maintain a body temperature? | [
"The whole thing comes down to balancing the thermal radiation you radiate away with the thermal radiation you take in from the Sun. How much heat you radiate depends on your own temperature, as your temperature gets higher you radiate away more heat. The heat you take in from the Sun depends mostly on the distance... | [
"it depends how warm you want to be, but as long as you can see it (even if you're out by pluto), you're being warmed by radiation. radiation travels best through a vacuum (e.g. space), whereas convection is heat flow within a flow. conduction is heat flow through a solid/liquid/gas that isn't moving.",
"in oth... | [
"Well the question you need to answer first is \"How fast does my body lose heat in space?\" If you answer that question then you find the distance where the rate your body takes in heat (in this case where you absorb enough light from the sun) matches the rate your body loses heat. ",
"In short if you want an ex... |
[
"What happens when we cut plastic?"
] | [
false
] | Just bit one of off a shirt and wondered what was actually being done to the polymer when I bit it. My understanding of plastics is that they're composed of monomers linked together via covalent bonds. This sounds like the bonding of diamond, but obviously it is not the same. Are there weak intermolecular bonds between long chains of polymers? how did biting the plastic affect the structure of it? | [
"It's all a matter of scale. While you commonly associate chemical bonds with something solid and strong - like diamond - it's only the case when there are both strong bonds and ",
" of them. Individual bonds are very weak and easy to break.",
"Depending on the type of plastic, there are varying degrees of cros... | [
"A telephone directory, also known as a telephone book, telephone address book, phone book, or the white/yellow pages, is a listing of telephone subscribers in a geographical area or subscribers to services provided by the organization that publishes the directory. Its purpose is to allow the telephone number of a ... | [
"http://en.wikipedia.org/wiki/Polymer",
"http://en.wikipedia.org/wiki/Fracture_in_polymers",
"In a polymer, you have long (or short) chains of lined C atoms that might have any number of groups attached to them. These chains might be cross linked. They might be ordered. They might be jumbled and knotted.",
"P... |
[
"Are there any predators or parasites that feed on intestinal worms, when they're in the intestines?"
] | [
false
] | null | [
"There are many hyperparasitic bacteria that use nematodes and cestodes as hosts. Most forms of multicellular life on earth can serve as host for at least one species of parasite, and that includes other multicellular parasites. The term you are looking for is \"super-\" or \"hyperparasitism\"."
] | [
"Would there be health complications with ingesting or trying to maintain a colony of the hyperparisites? Would a pill of them be an effective medicine for fighting these parisites? Or do we just not know enough about their effects?"
] | [
"Is it any better if your parasite has a parasite?"
] |
[
"Is there a \"light-horizon\" that represents that edge of the knowable universe with respect to any practical purposes?"
] | [
false
] | The universe is expanding. Not from a central point (because there may be no coherent way to speak of a central point), but from all points in all directions simultaneously. This has been revealed experimentally as all astronomical bodies recede from each other at rates proportional to their distance from one another! The farther away something is from an observer, from us, the faster it recedes from us. If the two bodies get far enough away from each other, their recession approaches, reaches, and exceeds the speed of light. This forms an effective "horizon" for the observer at either point, since distant stellar bodies are receding fast enough that their light traverse the ever-increasing distance between the observer and the horizon. In other words, if I'm understanding the idea correctly, even if the universe is endless, assuming that we are never able to travel faster than the speed of light, there is a necessary boundary formed for our knowledge and exploration generated merely by the expansive properties of the universe? Is this right? If so, why doesn't this get brought up more in discussions about the universe being infinite? If there is an absolute knowledge horizon for less-than-light beings (LTLs), can't we just treat the universe as having a very distinct "edge"? | [
"In other words, if I'm understanding the idea correctly, even if the universe is endless, assuming that we are never able to travel faster than the speed of light, there is a necessary boundary formed for our knowledge and exploration generated merely by the expansive properties of the universe?",
"Yes, there is... | [
"There is a 'cosmic event horizon' from beyond we will never receive any signal, however, this horizon doesn't correspond to the Hubble distance (where v=c), it is actually further away.",
"This is an excellent article about this",
", see the chapter titled \"Running to stay still\" which talks about exactly th... | [
"Scientifically speaking, we assume the explanation that requires the fewest additional assumptions. Sure we ",
" assume that somewhere out there beyond our horizon the universe wraps back around on itself... but that's an unscientific statement. ",
"Given all of the data we have available",
" the universe is... |
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