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Why is it easier to cook/warm certain foods in the microwave? | The reason is that microwaves ovens work through a mechanism called [dielectric heating](_URL_0_). What that means is that the way the EM radiation dumps heat into your food is by coupling to specific transitions in the molecules making up the food. One important transition is by rotating species with dipole moments. A typical molecule of this kind is water, which explains why foods rich in water tend to warm up more quickly. On the other hand other materials, e.g. bone or ceramic plates, absorb the microwave radiation much more weakly and as a result they can stay cool even when other food is already hot. |
What defines a planet? Why is Jupiter, a gas giant, considered a planet? | According to the [IAU currently](_URL_0_), a planet is a celestial body which: * is in orbit around a star, * has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and * has "cleared the neighbourhood" around its orbit. |
What makes a planet a planet? Like why Is Jupiter a planet is it's mostly made of gasses and why isn't Pluto which is made out of rock/ice? | The definition of a planet has been made pretty clear since pluto's "demotion". A planet must: - orbit the sun... Pluto does. - be spherical... Pluto is. - have cleared its orbit of other matter... **Pluto has not**. The last item is the catch. Pluto, being in the Kuiper belt, orbits with other bodies of various size. You can think of it as it hasn't 'dominated' its orbit... or it hasn't claimed its property as its own. There are many other bodies that we know of in our Solar System that fit into Pluto's new designation including one, Ceres, that is actually larger than Pluto. The definition of a ["dwarf planet"](_URL_0_) is the same as that of a planet minus that last item. Size and composition of the body is irrelevant. Edit: Oh, and of course, the body can't be so massive that internal fusion turns it into a star. |
What is sneezing? Why does it happen randomly? | A sneeze, or a 'sternutation' is basically a rapid expulsion of air from the lungs, via the nose and mouth. But you already knew that. A sneeze is typically triggered when your nasal mucosa (the membrane lining the inside of the nose) is sufficiently irritated. This may occur for a number of reasons, including inspiring foreign material, or irritation caused by viral infection of this mucosa. Irritation of the epithelium (the cells which line the mucosa), may result in histamine release, which may stimulate sensory neurons in the nose, sending a signal to the brain to initiate a sneeze via the trigeminal nerve network. Sneezing can also occur as a result of sinus nerve stimulation, in the setting of allergic rhinoconjunctivitis and congestion during viral infections. Interestingly, some people also sneeze in response to bright light, a full stomach and even eating or chewing a strongly flavoured mint. Hope this brief answer helps. |
If the cells in our bodies are only ~5-10 years old, why don't tattoos disappear in 5-10 years? | Check out [these past threads](_URL_0_). The short answer is that cells _aren't_ replaced every 5-10 years. There are many cells that don't replicate, thus are present since birth. Tattoo ink is injected below the basal layer of your epidermis - the layer that makes new skin - so it's not pushed out by skin turnover. Rather, some ink is engulfed by macrophages as part of your normal immune response, the rest is incorporated into the connective tissue of your skin as it is repaired. That said, tattoos do move and can fade over time. |
Why do electric motors have maximum torque at low rpms, while combustion engines have to be at high rpms to get maximum torque? | Also, steam engines generate maximum torque at zero RPM. |
Has it been shown that infinity exists in any form in reality? | The one that comes to mind is the [casmir effect](_URL_0_) which requires and infinite amount of zero point energy in the universe, as well as an infinite number of wavelengths of light. |
Why is it that the parasite that is transferred from one human host to another through mosquitos only appear to affect the human host and not the mosquito? | I'm not at liberty to say what the physiological reason for this is, likely some different set of conditions in a mosquito's body vs. a human's. However, if you look at it from an evolutionary standpoint, it makes sense. If something like malaria killed its insect host as rapidly as it does humans, it'd never get the chance to spread and multiply. This is an evolutionary disadvantage, and this is a common theme in parasites. It needs to take enough from its host to survive, but not so much that it kills the host, or else it stops receiving nutrients and dies itself. A sick, sedentary human is a prime target for mosquitos to bite and pick up the parasite. A sick, sedentary, or dead mosquito does the parasite no good, and the "bloodline" so to speak, stops there. |
What is happening in my liver when I consume alcohol that is so bad for it in the long term? | There are three things that happen with [Alcoholic liver disease](_URL_0_): * Fat deposits. Alcohol mainly gets metabolized by the liver, so all the energy from alcohol causes a lot of fat production in the liver which can cause fat deposits. (Some other foods, such as fructose can also cause this.) * Hepatitis/Swelling. When alcohol is broken down it is first turned into acetaldehyde before being turned into harmless acetic acid. If acetaldehyde lingers in the liver it will cause swelling. * Fibrosis/Production of excess connective tissue. (I don't really know the mechanism here.) All of these make the liver not work as well, and can lead to liver cells dying and all the associated problems with toxins in the blood. These can also lead to narrowing of the blood vessels feeding the liver which can lead to more acute problems like internal bleeding. |
If a very large asteroid ( > 300 miles in diameter) hit the earth, what would happen to the asteroid? | An object that large would break through into the mantle. Anything that isn't vaporized will be swallowed up by the massive lava sea it just created. You'll also get smaller fragments that are blasted far from the impact site and will land elsewhere. |
What causes us to twitch and suddenly wake out of sleep? | These are called "hypnic jerks" and are a form of myclonus. You mention MDMA. Drugs sold as MDMA usually have some affect on dopamine and seratonin, and these are thought to be involved in some hypnic jerks. |
Can two stars in a binary system eclipse each other? | Yes. > If a planet orbited two stars orbiting each other, eventually one would overlap the other from a set vantage point on that planet. As long as they were all in the same plane. If the planet was out-of-plane compared to the binary system, then obviously the planet would always see two stars. > Would the view from the planet be similar to a regular eclipse, or would the one appear brighter, or would it not really be noticeable? The total luminosity of the binary system decreases when one star is eclipsed by the other. > Do the types of stars affect the visual outcome? Of course. The brightness and diameter of each determine how the eclipse will appear. In the case of neutron stars, keep in mind they are tiny compared to main sequence stars. _URL_0_ |
Could "double eclipses" happen in an exoplanet with two natural satellites orbiting a binary star system? | I don't think anybody has ever detected an exomoon around a rocky planet. That said, about half of all stars are part of multi-star systems so there are [many, many chances for this to occur.](_URL_1_) You could also arrange a double eclipse with a single moon. Some binary stars are [very, very close together](_URL_0_) to the point that they distort eachother into egg shapes and sun-sun eclipses are a daily or weekly occurrence. They're basically one object from a distant gravitational viewpoint and this is good if you want stable orbits to park planets in. |
Is there a reason that baldness in babies follows the same general pattern as Male Pattern Baldness? | I think you may have a flawed premise here. Babies generally don't follow male pattern baldness. If they have very thin hair, it is generally very uniform. Maybe someone else can give you a better answer, but I haven't been able to find a single example of a male pattern baldness newborn for about an hour now. |
Why doesn't cooking spicy food denature the capsaicin protein? | Capsaicin isn't a protein, it's a [small molecule](_URL_0_), so heating it won't have any chemical effect. In the strange circumstance that you wanted to try and break down the molecule using heat, you'd boil it off first, because it's volatile. Your pets, roomates and possibly neighbours also wouldn't be too happy. |
Are any volcanic islands currently being formed in the Pacific? | The Big Island of Hawaii continues to grow with each lava flow that reaches the shoreline, so you could say that in a sense it's still "being formed". [Lo'ihi Seamount](_URL_0_) is far enough from the other volcanoes in the system that it will probably be a separate island when it reaches the surface of the ocean (expected to be on the order of 10,000 to 100,000 years). |
When I'm sick and I blow my nose (seemingly endlessly) where does all that nasty mucous come from? How am I producing so much? | Mucus is produced in special cells called "Goblet cells". Mucus is actually a "heap" of glycoproteins: proteins with "branches" of polysaccharids. They become very viscous. Imagine a long strand with many arms, but then on a molecular level: take millions of these molecules and you end up with a thick fluid. When the goblet cell produces these glycoproteins like any other protein, they are stored in a large "bubble". When filled, the "bubble" inside the cell "breaks off" together with the part of the cell that contained the bubble. This bubble is often the bulk of the volume of a goblet cell. tl;dr: yes, mucous tissue in your nasal cavity and throat will just ccontinue to produce mucus, moreso when there are threats like dirt or bactera that need ejection. |
Why does a lit candle make a sound when you blow on it a little? | Sound is practically (just like wind) is a difference in air pressure. You are making sound using your flute/sax because of this (_URL_2_ or, if you want to be scared: _URL_2_ ). Blowing a candle is like a the wind blowing a flag but in a milder way; pressure difference between warm and cold air can make a ~~noise~~ sound if disturbed by your blow. |
What happens in your vocal cords when you sing falsetto? | In regular singing/speech production, the entire vocal cord vibrates together to create the sound. In falsetto range, only the ligaments on the edge of your vocal folds vibrate together. They can vibrate faster, hence higher in pitch, but often do not close fully, hence the "airy" and light note quality. |
How did the planets and moons become spherical? | When an object is large enough, gravity will reduce the energy of the object by bringing it into a spherical shape. Edit to fix typo: "ship" -- > "shape" |
How much fuel is likely to evaporate from my car if left unused for 3 or 4 months? | Assuming the gas cap is on tightly, none should evaporate out. Yes, evaporation will occur within the tank, but the gas will condense as well. |
If most of the weight of a rocket is fuel, would there be a limit to how much fuel you can carry or would thrust increase as fuel decreases due to less weight? | Here's the formula you are looking for: _URL_0_ |
If there is no oxygen in space, how do stars continue to burn without the basics for fire? Fuel, Oxygen, and Heat. | Stars do not chemically burn like a campfire. Rather, due to the intense heat and pressure of the core, a star fuses hydrogen into helium which releases a tremendous amount of energy which goes towards heating the star and producing light. Depending on a star's mass and age other elements may be fused, which may release energy or even take energy. |
Does a dog hear a human talking the same way we hear another person speaking a completely foreign language? | IgorNovlkov gave a good answer, you might be interested to know that dogs ears are structured differently from ours, so they hear completely different pitches. Our voices would sound remarkably deep to them. |
What specifically allows ants to lift such huge masses compared to their own mass as compared to humans and other large animals. | The answer is more physics-based than anatomy-based. Basically, their great relative strength is because of their small size. Strength of a muscle is based on its surface area, which, being a two-dimensional measurement, decreases by a factor of 2 (x^-2) Size of an muscle is based on its volume, which, being a three-dimensional measurement, decreases by a factor of 3 (x^-3) Smaller animals like ants are much smaller in volume, but greater strength relative to that volume, than larger animals. The larger an animal, the more disparity there is between mass and strength. The smaller the animal, the less disparity. [A source article, if you want one](_URL_0_) Their muscles are actually no stronger than a human's on a pull-for-pull basis. This also means that, if an ant were human size, it would have a much more difficult time lifting a car than our elementary school teachers had us believe. |
Why does it seem like we have to pee more often when we drink alcohol as opposed to other liquids? | Alcohol inhibits the pituitary secretion of anti-diuretic hormone (ADH), which acts on the kidney to reabsorb water. Alcohol acts on the hypothalamus/pituitary to reduce the circulating levels of ADH. When ADH levels drop, the kidneys do not reabsorb as much water; consequently, the kidneys produce more urine. |
Why can't you find a new prime number by doing (P1xP2xP3...Pk)+1? | What we know is (P1xP2xP3...Pk)+1 is not divisible by any of the primes P1 through Pk. This does not mean that (P1xP2xP3...Pk)+1 is prime, only that it is divisible by a prime other than P1 through Pk. And after 2 and 3, every prime is of the form 6n+1 or 6n-1, but this does not mean that every number of those forms is prime. |
How much more mass would Jupiter require to begin the fusion process? And how much volume would it gain if it were to start? | Jupiter could be made a 'brown dwarf' by making it about 80 times more massive. This isn't a set limit though - depending on formation history and composition brown dwarfs can fuse deuterium with as little as ~10x the mass of Jupiter. Remarkably, it's volume would stay approximately the same. Jupiter is about as large as a planet can get, in terms of volume. If you were to add more mass, it would result in the planet becoming denser, rather than larger. Put simply, no one is ever going to 'ignite Jupiter.' |
Can a radio antenna be used to detect visible light? | Theoretically, yes. However, the antenna would have to be so small as to be realistically impossible. At 400 THz, a half-wave dipole antenna would have to be 325 nm long, and thin enough to make that look like a wire (approx two-to-three orders of magnitude, or about 500 pm wide). Also the energy collected by this antenna would be so small, and the frequency so high, that it would be essentially unnoticeable. |
Why aren't solar panels black and mat? | A huge aspect of photovoltaic design is developing effective anti-reflective (AR) coatings to promote absorption. Currently, silicon PVs are etched to yield a thin top SiN layer, which appears blue. Keep in mind, these AR coatings aren't meant to absorb any energy, just to allow as much light through to the active region as possible. This stuff is tricky business, decades of research have been spent optimizing this process and it is far from over. Currently, the best process we have yields cells that appear blue. |
How do we know the decimals of Pi are infinite if we've never counted far enough? | It's not hard to prove using a bit of geometry and some calculus that pi is what's called an "irrational" number—that is, a number that **cannot** be represented as a fraction of two integers. Another famous example of such a number is the square root of 2. Now think about how decimals work. (We'll stick in base 10 for now, but this works for any base). * First you write an integer, say 3. * Then you put a digit after the decimal point in the tenths place, to make something like 3.1, which represents the number 31/10. * Then you add another digit in the hundredths place, to make something like 3.14, which represents the number 314/100. * And so on. Once you put a digit in the nth place, you're representing your number as a fraction with denominator 10^n ; but pi **cannot be represented as a fraction of integers**, so no finite decimal expansion is the actual value of pi. Therefore, you need infinitely many digits. |
Do planets fall out of orbit just as our satellite fall out of orbit? | Satellites in LEO (low earth orbit) are still in a very thin atmosphere and thus experience drag and eventually slow down enough to start descending, hitting thicker atmosphere and then burning up. The planets generally aren’t considered to be in the suns atmosphere, although the planets do experience ‘solar winds’ |
What happens to eyelashes that get stuck in your eyes? | It gets blinked out. Your eyes eventually ignores it and it falls out without you feeling it |
If the earths crust didn't split into tectonic plates, would the continents have even drifted at all? | You can look to Mars for an example of what you describe. The martian lithosphere is much thicker that ours, and although incipient rifting began, it was unable to carry through into plate spreading. Hence there is no plate tectonics on Mars. What you *do* have is a huge rift valley along Valles Marineris and the solar systems largest volcanic centres. The gigantism of these shield volcanoes reflects the fact that they remain in place without moving above a given hotspot, as the Hawaian system does for instance. |
How do the lungs heal after a smoker quits? | Part of the answer, to the best of my knowledge (coming from psychiatry): Smoking causes changes in the epithelial cells of one's airway. This includes the loss of ciliated epithelial cells as they are replaced with tougher squamous epithelial cells. This replacement is known as metaplasia, and it is a reversible process. What is the significance of this shift in epithelial cells? Lack of cilia causes smokers to be less able to move mucous out of the airway, leading to the "smoker's cough". Cessation of smoking, which leads to a decrease in the irritation of the airway, can eventually lead to the body reversing the process, recovering the cilia and allowing the individual to better clear their airway. |
How do we have pictures of our galaxy? | We don't have pictures, it's more of a painting. Ex. You're sitting in a room, you could make a bird's eye view of the room without being at the bird's eye point of view. So what scientists/astrophysics nerds along with programmers have done, is made a map of everything in our galaxy (drawn it out from our PoV, with distance and size relations etc) and so with programming (like in Google maps), you can change your point of view, and thus we kinda took a picture of ourselves I guess you could say. Pretty much they just mapped everything inside our galaxy and then changed PoV ;) |
Why do invertebrates not get cancer? | They do. * [Tumors in the Invertebrates: A Review](_URL_2_) * [Tumors in invertebrates: molluscs as an emerging animal model for human cancer](_URL_0_) * [Tumors in invertebrates](_URL_1_) |
If we can see stars and galaxies like they were billions of years ago, shouldn't we be able to see either the beginning of time or the end of the universe if we zoom in far enough? | There's no need to zoom in. We can easily see light from the very first moment when the universe became transparent, it turns out this is just the cosmic microwave background. |
Why are there more islands in the Pacific Ocean compared to the Atlantic Ocean? What causes this difference? | There are several factors. Firstly, the pacific is obviously bigger so it's normal to expect more islands in it. Secondly, the Atlantic is growing (South America and Africa are moving away from each other) so the newly formed ocean bottom as this happens is at the bottom of the ocean. Some places in the Pacific are moving towards each other, hence places like Japan and New Zealand. When two plates push together it makes sense that parts of the ocean stick up above the water. |
If they pointed the Hubble telescope back towards the Earth, what's the smallest thing it could see? | The Hubble telescope has an angular resolution of 0.05 arcseconds and an orbital height of around 350 miles. Pointed straight down at the surface of the earth, this translates to a spatial resolution of around 10 centimeters. However, the telescope itself is optimized to look at things that are very far away, meaning they don't move very fast relative to Hubble's field of vision. As a result, objects on the surface of earth are moving too fast for the telescope to "track" - so you can't actually get an image of the surface of earth using Hubble. |
What happens to plants if they are exposed to sunlight for longer periods of time | Usually plants don't *need* nighttime to live, only to flower, if they take flowering cues from the length of the day. "Vegetative growth phase" is when the plant does most of its leaf-producing and photosynthesis and they often love to be in 24-hour light during this phase. |
How are new ant colonies formed? Do a group of ants just decide to leave one day and start anew? | The queen ants and the male ants are both born with wings. There is a mating season every year where all of the queens and males fly away from their colonies and look for a mate. After a queen finds a mate and is inseminated, the male dies and the queen finds a good place to start a new colony. After finding a suitable place the queen removes her wings and digs a small burrow and starts laying eggs which results in a new colony being formed. |
If Dark Matter is changing the rotation speed of stars in every galaxy, why does it not change the rotation speed of planets around stars? | Well, the key word here is "measurable". Dark matter likely has some effect on planets, but a negligible one. Dark matter is extremely diffuse, even when it is "clumping" into dark matter halos that are found around all galaxies. This means that you are only likely to have a measurable effect on objects of galactic scale, which really begins with stars on up and their paths through the galaxy. Anything bound to a star's gravity, such as a planet or asteroid, is much, much more closely bound to the star than could be affected by the small amount of dark matter diffused in that relatively small volume of space. |
Is it possible for an earth-based telescope to capture images of stars (not the sun!) during normal daytime conditions? | Yes. It is of course very difficult in visible light given the large sky background, but it is possible for very bright stars. It gets easier in the infrared and radio, where the sky is much darker; radio telescopes in particular basically don't care at all that the Sun is up. For anything most people think of as a telescope, though, daytime observations are not useful. |
Why does your nose "adjust" to smells? | Because you need to be alert for other smells, your brain filters it out if its constantly present inorder to be able to catch other smells (that could be dangerous/important/etc) This is why people usually don't notice their own smell or their own breath |
If you smell something really bad, why does the smell linger for a long time in your nose even when it has dissipated from the air? | There are two reasons for this, the first reason being that your sense of smell is based off of (mainly) receptors in your nose. Certain receptors bind certain molecules signalling different smells. These receptors also have a binding affinity/dissociation constant that may vary depending on their specificity and the molecule that has bound to the receptor. As a result some molecules may "linger" so you keep smelling it. The second reason is a sort of placebo effect where thinking about when you dealt with that smell also leads to the activation of the other neurons associated with the memory i.e. the ones telling you it smells bad. |
How large could a rocky planet get? | First, I think you should distinguish between size and mass. There are some planets that are more massive without being much larger than Earth. For example the largest known planet is Kepler-10c, with a mass similar to Neptune, but it only has a radius 2.35x bigger than Earth. You also must think about the difference between a gas giant and a terrestrial planet. Most people think of it as either gaseous or rocky, but large planets gravity will suck in gases, so they will have large atmospheres. Maybe even gaseous enough to be called a gas giant? Also, most people don't know that gas giants DO have a rocky core! It's even theorized that a gas giant's atmosphere could be destroyed by their star, leaving a terrestrial planet behind. So instead of just terrestrial, or just gaseous, it's actually much more of a gradient. If you really want an answer, around 2.5 Earth Radii, or about 20x Earth's Mass is about the limit for terrestrial size planets. |
How is it that some rivers have fresh water while the seas that feed the rivers have salty water? and what happens when a river that has fresh water meets one with salty water? | You have it backwards: rivers flow to the sea, not from it. See wiki: _URL_1_ The idea that "salty water doesn't mix with sweet water, and god sets a barrier between them" is nonsense, as I presume you now know. There is, naturally, some mingling of salt and fresh water at the point at which the two meet, but the extent to which it extends into the river depends on the flow of the river. |
What causes the blackened skin under your eyes when you don't get enough sleep? | "The physiopathology of periorbital hyperchromia (which is the word for dark circles under the eyes) is not clearly defined; however, blood flow stagnation seems to be a determinant factor involved in the development of this process. This concept is supported by the fact that in the last years, cosmetic companies have been presenting preparations for ‘‘dark circles’’ containing mainly ingredients for stimulating local blood flow." ([Source](_URL_0_), p.129) |
Why do our eyes become red when we are deprived of sleep? | When the small blood vessels on the surface of the eye (sclera) become enlarged and congested with blood, as a result of insufficient oxygen supply to the cornea or the tissues covering the eyes, the eyes can become red. Sleep deprivation, alcohol, and decreased tear secretion at night can all contribute. |
If skin cells constantly shed, how are tattoos permanent? | Only the top layer of skin cells shed. Tattoos are injected into the subdermis, which does not shed. Therefore, permanent. |
Why does warm air outside have a distinct scent to it as opposed to cool or cold air? | Warmer temperatures would increase the vapor pressure of nearby substances, so you would be able to smell more of the volatiles that are always present in your surroundings and simply not potent enough to detect when cold. Just like a plate of cold food from your fridge would smell much better and stronger once you heat it up. It would depend on your local environment what's directly responsible for the smells of a hot day. There's also a substance called petrichor that can be released by dry soil when it gets rained on that's responsible for that "rain" smell. There could easily be another similar process involved to produce a distinctly "warm" smell. |
Why does being sick sometimes kill your appetite? | Only thing I can think of is the immune system works better when energy doesn't have to be directed towards processing food and drink. It is well known that the body heals deeper when fasting. Not sure what actually happens inside the body when you're ill and something tells your brain it does'nt want food. |
TIL That the solar system, and subsequently the planets, rotate because the galaxy rotates. But why does the galaxy rotate? | All things rotate because the gas clouds from which they collapse have some initial motion (swirling) associated with them. The swirling means that there is some amount of angular momentum in the system. As the cloud collapses to form a star, the radius of the object decreases. Conservation of angular momentum says that the angular momentum of the cloud before the collapse must be the same as the angular momentum after the collapse. Since the radius gets smaller, the speed of rotation must increase. |
Why are not all blood-borne diseases able to spread through mosquitoes? | They have to be able to survive the transmitting host. Also a mosquito bites you and injects its saliva, and I forget it acts like some sorts of anti coagulant and blood leaks out. The basis being there is no blood from the mosquito from the previous victim being injected and the disease they do spread are found in saliva and not blood. I 100% dont remember it in all detail but I am sure someone is an expert here in bugs and can finish up. But I can tell you is the reason why is the blood born pathogen even if the skeeter sucked it up that blood wouldn't mix with the next victim. |
How complicated are computer chess programs, and what is the simplest chess program that could still beat the average chess player? | A popular method for playing fully observable board games is the Minimax algorithm, with extensions such as alpha-beta pruning etc. This algorithm is actually fairly general, in the sense that all you have to do is give it a function for evaluating how good the current game state is from each player's perspective. The hard part is designing good heuristics that can accurately predict when a board configuration is likely to lead to a victory for one player or another. IBM's Deep Blue system, which is a quite out of date but still a good example, used a fairly complicated heuristic which had parameters tuned by examining a large database of games played by chess grand masters. |
If I play music at the same volume on two speakers then will the overall volume of the music increase? | When you have two noise sources it will be louder. It is essentially the same thing as having two light bulbs next to each other. It does not add up directly though - it won't be twice as loud. If you have two noise sources with a sound level of 100 dB each the total will be about 103 dB. |
If my headphones have bigger speakers will the battery life on my iPod drain faster? | Ramast's answer is incorrect. Changing the volume doesn't change the output power, it changes the output voltage range. At a constant volume level, if you switch to a set of headphones with twice as much impedance, you'll halve the sound output, but you'll also halve the power consumption. The parameter you care about is how well sound from the headphones couples into your ears. This is reasonably well approximated by putting the headphones on and asking someone to judge how much sound they can hear near you. |
Does turning up the volume in headphones drain the battery of my phone/mp3 faster? | I don't know the general answer for consumer electronics, but at least in the case of the music playing electronic circuit I made for a class project, it makes almost no difference to power consumption whether you have the volume at 10% or 100%. The circuit component that controls volume is called an amplifier. You can create amplifiers by connecting various types of transistors with other circuit components to create a circuit which does use varying levels of energy based on amplification level, or a circuit which uses almost exactly the same amount of energy regardless of amplification level and just wastes more energy as heat when the circuit is on and the volume is turned down. There are many possible amplifier designs, and they all offer a different tradeoff between amplification ability, signal distortion, cost, and energy use. I can't tell you what kind is commonly used in portable mp3 players, but perhaps someone else can. |
Is there a theoretical limit for how large a star can become? | As mentioned previously by /u/MadFlavour there was a study done on the the [Arches cluster](_URL_2_) which is a new star cluster, the researchers did not find any stars whose mass exceeded 150 solar masses so they assumed that 150 solar masses was a limit. However the discovery of the [R136 star cluster](_URL_0_) (warning, it's a PDF) seems to break that limit with several stars such as R136a1 which has a mass of ~265 solar masses. Another possible limit could be one posed by the [Eddington Limit](_URL_1_) which is used to explain the mass loss of massive stars such as R136a1 which is speculated to have started with ~300 solar masses. |
How many stars I see in the night sky have planets orbitting them? | [wiki](_URL_0_) entry... Current estimates suggest that there are at least 1.6 planets per star on average. The actual figure may be higher. Alternatively - more than 50% of stars are expected to have planets. We are still very much in the early days of finding planets around other stars. The degree of uncertainty is very high. |
Why didn't the European settlers of America contract terrible diseases? | As far as I know, diseases like that did not exist very much in the Native American population. Europe was a great breeding ground for multiple reasons: It had a denser population that the Americas, diseases that started as isolated cases were quickly spread by war and trade, and the Europeans also used more domestic animals, which spread even more types of disease. Over time, European population began to gain immunity to these diseases. In addition Native Americans were not very genetically varied (compared to Europeans) and as a result, if a virus was able to kill one person, it was most likely able to kill everyone. |
Are the planes of solar systems aligned with that of our Galaxy? | Ours isn't. It's off by about 63 degrees. There's more information here if you want it. _URL_0_ |
Diamonds in the sun? | Above a certain temperature (several thousand degrees), all chemical bonds break apart, no matter how strong they are. The pressure inside the sun is great enough for diamonds to form, but the temperature is far too high for any assemblage of atoms to persist for more than a few microseconds. Regions of stars like the diffuse atmosphere and sunspots are cool enough that simple molecules can form; these have been [detected through spectroscopy](_URL_0_). I don't think a group of carbon atoms would have time to create a large enough structure (you can't really call 2-10 atoms a diamond) before the grouping was destroyed. There is a strange exception, and that is the discovery of a white dwarf star that has cooled enough to have crystallized into a giant diamond, but I don't think that was what you meant when you asked. |
Why Does Radiometric Carbon Dating Reflect the Age of an Object Being Dated if the Carbon is Older than the Object? | When animals are alive, they generally contain a set proportion of the isotopes and elements that are relevant for radiometric dating. These proportions only start to change after the death of the animal. So we know the starting proportions, the decay rate, and the current proportions, and can thus calculate the date of death. |
Nothing can go faster than the speed of light. but didn't the expansion right after the Big Bang move far faster than lightspeed? | Two things to keep in mind: 1) The expansion of the Universe doesn't have a speed. It's a speed *per distance*, meaning there are always points near you which are expanding away from you more slowly than light, and there are always faraway places expanding away faster than the speed of light. 2) The speed of light limit really applies to objects moving *through* space. The expansion of the Universe, though, is an expansion *of* space itself. These are completely different things. The former really describes ways of sending *information*. If information were to travel faster than light, cause and effect would be broken, signals would be able to travel back in time and into their own past, so the laws of physics conspire to prevent that from ever happening. But the expanding Universe can't be used to send signals - after all, everything moves away from each other! |
Why are galaxies (roughly) planar instead of spherical? | Galaxies come in many types. Some are spirals, while others are more spherical. These are called [_URL_0_] elliptical galaxies. We think that elliptical galaxies form when a spiral galaxy merges with other galaxies, but the jury is still out! |
Theoretically, wouldn't greenhouse gases eventually stabilize temperatures between day and night? | This question can be answered by looking toward the surface of Venus. Its dense atmosphere allows for the surface to stay nearly uniform at around 460-470 degrees Celsius. *edit*punctuation and grammar |
How large would the universe be if there was no empty space between protons, neutrons, and electrons? | In the primordial, young, small, hot universe, there weren't protons and neutrons at all. Nucleosysnthesis didn't occur until there was enough space to have them around. So the question is sort of ill posed. Expect varying answers. |
Why do we not remember the first few years of our lives as adults? | It's called infantile amnesia and it's explained pretty simply by the fact that the brain structures such as the hippocampus and amygdala that encode and retrieve memories aren't fully developed yet. Many times the events that we think we remember from young ages are things we've been told by our parents or others that we've falsely created a memory for, based on their retelling. |
Why is ocean water clearer in some tropical parts of the world and darker in non-tropical parts? | Good question, albeit not a perfect correlation between latitude and clarity. It has to do with primary productivity, which is driven by nutrient supply. The more productive the water, the more "cloudy" or full of life. [Here](_URL_0_) is an image and explanation of global chlorophyll (primary productivity). |
Why is the water in tropical oceans so clear compared to temperate seas/oceans? | Due to the availability of nutrients the mid/high latitude oceans contain a lot more algea and plankton. This leads to the characteristic green colour of northern seas for example. Additionally in places like the north sea you have frequent rough weather and high ship traffic coupled with a shallow and muddy seafloor, which leads to higher amount of suspended particles in the water. |
How do spiders cast a web between two far apart things? How do they get from one side to the other? | wind drift, either at the end, or releasing web and allowing it to drift and stick to distant object...then move along the web and tie the outer end down. |
How come Helium-3 is stable but Hydrogen-3 isn't? | The first thing to realize is that, on the subatomic scale, the "nuclear strong force" is much, much stronger than electromagnetic repulsion. This is why you can have stable nuclei with dozens of protons in them. Next, you have to know that neutrons are ever-so-slightly more massive than protons. Because of E = mc^(2), this means that turning a neutron into a proton releases (quite a lot of) energy. That means that neutrons can undergo spontaneous beta-decay to form a proton and an electron. So this tells you why He-3 is more stable than H-3, but you're probably wondering at this point why He-3 is more stable than Li-3, if protons are more stable than neutrons! That's because, like how electrons fill orbitals at different energies, nuclear particles fill "shells" at different energies. So while the 2nd neutron has enough energy to turn into a proton in H-3, the lone neutron in He-3 doesn't have enough energy to turn into a proton to make He-3 into Li-3. [Reference](_URL_0_) |
Soap/shampoo can be any color but the suds are always white. Can someone explain? | They're diluted when used. The bubbles, being on the micron length scale, also scatter visible light making the foam look white. It's why milk is white and not transparent. For smaller dispersions of particles, bubbles or emulsions smaller wave lengths of light are scattered more intensely and so they can appear bluer in colour - all whilst the components themselves aren't necessarily blue coloured. |
Why do our tastes in food mature as we grow up? | _URL_0_ Your taste buds change as you get older. I can't find the source for another reasoning, but he said that taste buds spread out when you get older, allowing for appreciation of complexion without possible overwhelming intensity. |
How can the largest stars have such low densities and still function as stars? | Core temperature is the key. Larger stars have much larger temperatures in their cores. For the proton-proton chain (the primary fusion mechanism in the sun), the reaction rate is proportional to density^2 and temperature^4. So if you decrease the density of a star, you can actually maintain the same reaction rate by making it hotter. For the CNO cycle (the primary fusion mechanism for larger stars), the reaction rate is proportional to density^2 and temperature^17. This extremely strong dependence on temperature means that large stars can be much less dense than the sun while still producing more light. While red giants like Betelgeuse don't use either the PP chain or the CNO cycle in their cores, I hope I've illustrated the importance of temperature in the fusion rates of massive stars. |
Did The Universe Expand Faster Than Light? | Here's the FAQ compendium on the topic, * _URL_0_ There is a definable "recession speed" which can exceed the speed of light, but it's not really a physical speed. The speed arises moreso from that we're looking at a different reference frame and not necessarily proper motion of the body itself. |
What are the rates of lung cancer and similar smoking diseases in chronic marijuana users? | I don't know about rates, but several studies^[1](_URL_0_),[2](_URL_2_),[3](_URL_1_) have shown cancer-inhibiting effects of THC, even in lung cancer, so I wouldn't be surprised if lung cancer rates are lower. Edit: Sorry for the crummy link for the first one, but [Nature's](_URL_3_) link wasn't working. |
Do ant colonies share a sleep/wake cycle with all ants sleeping at once, or does the colony operate continuously with ants resting individually on their own intervals? | Great question. This varies considerably between different ants depending on what species and environment you are in. Typically, an ant colony has a peak activity level for given times of the day and all workers follow that pattern of higher activity and lower activity within the nest. For example, the eastern black carpenter ant (Camponotus pennsylvanicus) is crepuscular with the majority of worker activity in the wee hours of the morning or dusk. Other ants are completely noctural and some are only active during the day. Some ants in the Southwestern desert actually use these difference in activity timing to screw with thier competitors: The nighttime-foraging harvester ants actually block the nest entrance to other daytime-foraging harvester ants. _URL_0_ |
Why do different mammals have different body temperatures? | The main reason for mammals to maintain a specific body temperature is to control the speed at which chemical reactions happen within cells. Almost all functions in a cell are aided by enzymes. Enzymes will catalyze a reaction faster at a higher temperature and slower at lower temperatures. A change in just a few degrees can be enough to dramatically affect these reactions. The change in the reaction rate may be tiny but when you consider that most of the reactions happen in a few milliseconds it doesn't take much to affect how a cell functions. The difference in body temperature comes down to a difference in enzymes and speed of metabolism in different animals. |
Will a solar panel generate more electricity when moving towards the sun? | I can't give you a full answer, but there are two main effects that have to be taken into account. As the panels move towards the source, the energy of the photons gets blue-shifted, so the panels would be receiving a greater energy flux overall. However, solar panels are optimized to collect a specific frequency of light. If the light gets shifted above the optimal range, the overall energy collected could decrease. |
Are there any types of balloons that don't lose helium over time? | Nope. Even the world's best vacuum systems will, in general, leak a bit of helium. Its simply too small, light and non-reactive to be contained by most materials. I have spent many hours trying to bring down my helium peak in high vacuum experiments. |
Is it possible for a terrestrial planet to be something other than solid and spherical in shape? | Planets are spheroids by current IAU definition, and nothing low-mass enough to have an irregular shape would naturally produce terrestrial conditions, so that aspect must apply. As for solid, there is no physical requirement that the *surface* be solid, but liquid surfaces that are too thick would contribute vapor to the atmosphere and build it up to supercritical pressure and temperature. That could result in conditions like Venus, or at a further extreme, a low-density "gas dwarf" planet somewhere between Earth and Neptune in size. In either case, non-terrestrial in terms of surface conditions. Earth's ocean at its deepest is only 0.0017 the width of its mean radius, so the only example we have for what produces the conditions we recognize has only a *very* thin and non-exclusive liquid layer. |
[Physics] What happens to the kinetic energy in a car involved in a crash? | A crashed car will indeed be hotter, though I'm afraid I couldn't put a number on it. If you take a small bendable piece of metal like a paperclip and bend it back and forth quickly, you can make it quite hot to the touch; bending metal causes internal friction which releases heat. |
[Physics] What happens to kinetic energy when car stops? | almost none of the energy goes into rotational energy of the Earth. I'll use linear momentum instead of angular momentum (because you also do expect the car to give the earth linear momentum), but the conclusion is the same. From conservation of linear momentum: M v_E = m v_C where v_C is the original speed of the car and v_E is the final speed of the Earth. So the final kinetic energy of the Earth is E_E = 1/2 M v_E^2 = ( 1/2 m v_C^2) * (m/M) = (m/M) E_C so the kinetic energy given to the Earth is suppressed by a factor of m/M. |
Why does water make paper products translucent? | This was an exam question on the oral part of a qualifier exam I took. The easiest answer to understand is that water changes the index of refraction of paper to be closer to water so that light penetrates it easier. |
Why are astronomers focused on creating giant telescopes as opposed to giant arrays of smaller telescopes (lets ignore radio telescopes for now)? | When you integrate the signal from an interferometer, you're just getting a slice of the image along any two telescopes in an array. The slice will have very good resolution but if you don't build a lot of telescopes to give you many slices, you won't have enough information to fill in the holes. Also, doing the integration is computationally expensive and you need to sync all telescopes very precisely, so it adds a lot of complexity vs just building one very giant telescope which we know how to do very well. |
About recycling plastic | Recycling isn't, generally, profitable without subsidies. To answer your question would require know what, if any, subsidies are available to you. Yes people currently recycle plastics, as to whether or not it's profitable, you'd have to ask them or look at their books. Some are privately owned companies so the information may not be available. However, some like waste management are publicly traded, those you can find their last year financial logs via the SEC of you're willing to pour over them (I'm not). As for whether or not recycling plastics will ever be profitable outside of subsidies... There's no realistic way to say. Not all plastics are created equally, some are more easily recycled than others, and the regulatory environment as it pertains to everything from plastics manufacture to emissions from recycling plants is subject to change at almost any time. Because of those factors, your last question, while a very good one is near unanswerable. |
Does Coffee Stunt Your Growth? | This myth has been pretty thoroughly debunked over time. Short little [New York Times](_URL_0_) column summarizing the studies. |
Why does coffee make you poop? | [This](_URL_0_) article provides some possible explanations: *We suspect that coffee may induce a 'gastrocolonic response' by acting on epithelial receptors in the stomach or small bowel. Such a mechanism could be mediated by neural mechanisms or by gastrointestinal hormones.* *Coffee has been shown to promote release of Gastrin which can increase colonic spike and motor activity. Cholecystokinin is another putative mediator of the 'gastrocolonic response' but there are no data on the effect of coffee on CCK release. Another possibility is that the colonic response to coffee could be mediated by exorphines. Both regular and decaffeinated coffee contain exorphines that can bind to opiate receptors. Opiate receptors, both in the brain and within the gut wall, mediate important effects on colonic motility; Sun and his colleages have shown that opiate receptors are necessary for the colonic response to food.* |
What is the temperature of space without stars? | It's about 2.7 kelvin due to the cosmic microwave background. |
What is it in some foods that makes them require refrigeration? | Sugar and salt are natural preservatives. To determine whether you need to refrigerate something, you need to think about the growth factors for bacteria and mold. Jelly, for example, has a high sugar content, making it an unsuitable environment for bacteria, but a high water content, making it highly suitable for mold. For this same reason, you can leave things like cakes and pies out for extended periods of time. (You can, in fact, leave jelly unrefrigerated for awhile as well.) Peanut butter has a very low moisture content, a high sugar content, and a high salt content, making it undesirable for both mold and bacteria. Thus, it does not require refrigeration. (100% natural peanut butter, on the other hand, has no preservatives and does in fact require refrigeration.) Source: layman food buyer |
If flowers are brightly coloured to attract pollinating insects, has the average brightness increased over the years? If we went back far enough, would flowers be dull and bland? | Pigmentation in organisms can change greatly over relatively short timescales. Consider how humans developed such a wide spectrum of skin colors in since leaving Africa less than 100k years ago. Thus if color brightness is a strong selective pressure on flowering plants, I would expect that colorful flowers appeared almost immediately (geologically speaking) as the selective pressure existed. |
Is the Universe Spinning? | I know the answer to the bonus question is no. Gravity is created by the mass of bodies. |
What happens to data when you delete it off of a cell Phone or a hard drive? | When you delete something, the information remains but the portion of the drive that contained the item is "marked" as being usable at a future time. At some point the item may be become unrecoverable if that portion of the drive gets written over a good number of times. |
Is the universe itself spinning just like galaxies do? | This is a good question, and it has been answered using careful observations of the cosmic microwave background. As explained in [this article](_URL_0_) about the search for any sort of universal anisotropy (that is, a difference in what you see in the universe depending on the direction you look), the odds that our Universe is anisotropic are 1 out of 121,000. We will never be able to exclude an immeasurably small rotation, but the answer to your question seems to be no, to a high degree of confidence. |
What is the evolutionary advantage to honey bees that they die after delivering a single sting? | _URL_0_ They're mostly there for interinsect warfare. They only break when stinging an organism with thick skin like a mammal. When stinging a bee or other insect with thinner skin they can repeatedly sting them without it breaking off. |
Are there any cognitive (or other) benefits I'm missing out on by listening to audiobooks rather than reading the book? | Well the most obvious thing would be spelling. |
Will we ever be able to see beyond the edge of our observable universe? As time goes on we are able to see further and further, but is the edge just going to stay the same, or possible have less to see since the outer galaxies are expanding faster? | By definition, we will never see beyond the edge of the observable universe. But the radius of the observable universe does grow over time. If you are asking whether new galaxies enter our observable universe as time goes on, then, yes. Galaxies up to a current distance of about 65 Gly will eventually enter our observable universe, albeit when they do they will be much farther away than they are now and their light will be incredibly redshifted. But no farther than that. |
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