title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"I can equalize my ears at will, what muscle am I using to do this?"
] | [
false
] | null | [
"The OP doesn't appear to be using the Valsalva Maneuver. Many people, myself included, have voluntary control of opening the eustachian tubes without the need to use that technique. "
] | [
"\"The eustachian tube joins the tympanic cavity with the nasal cavity (nasopharynx), allowing pressure to equalize between the middle ear and throat.\"",
"Yo Dawg, I heard you like popping your ears!"
] | [
"There are four muscles associated with the function of the Eustachian tube:",
"Levator veli palatini (innervated by the vagus nerve)",
"Salpingopharyngeus (innervated by the vagus nerve)",
"Tensor tympani (innervated by the mandibular nerve of CN V)",
"Tensor veli palatini (innervated by the mandibular ner... |
[
"What exactly is the Doppler effect?"
] | [
false
] | I don't really understand it that well, correct me if im wrong but I'm assuming it's the way sound changes as it passes you. | [
"The Doppler effect is the change in frequency of a wave due to the fact that the source is moving relative to the observer."
] | [
"Imagine a fire truck: When traveling towards you, the siren sounds are higher in frequency because it has a shorter in wavelength. ",
"Think about it because as the fire truck moves towards you, the wavelengths are squishing together and running out of room before it hits you. ",
"Once the fire truck passes yo... | [
"Looks like you got some answers already but I always like to bring up that the same type of effect happens to light coming from distant moving objects like stars and galaxies. They will seem to be completely different colors because the light coming from then is moving towards us much faster than they are moving."... |
[
"Do spiders actually consume flesh when they bite humans?"
] | [
false
] | This question stems from my girlfriend's fear of spiders and her uninformed assertion that they actually "eat" her when they bite--somewhat similar to the way that mosquito bites are the product of them actually deriving nutritional value from human blood. As such, I am less interested in whether a large spider like a ... | [
"Are they eating you when they bite you? No.",
"When a spider bites you they do its to kill you. Its the same when they bite insects that get stuck in their web. The venom paralyses and/or kills the insect, they then wrap it up in silk and excrete digestive juices to break it down to eat.",
"Can spiders kill pe... | [
"Spiders don't attack something that much bigger than them, their first instinct is to run away from us. Biting is a defensive mechanism, nothing else. As for the whole eating us, thing, they are physically incapable of eating anything, they don't have mouths."
] | [
"they are physically incapable of eating anything, they don't have mouths.",
"ಠ_ಠ"
] |
[
"What would a Bubble do in zero gravity/space ?"
] | [
false
] | [deleted] | [
"In zero gravity bubbles won't have any weight, thus no buoyancy to counteract it. Diffusion should take occur if the bubbles are of sufficient size (micrometer order of magnitude), as long as there are other molecules around (such as air e.t.c). ",
"But in space, the pressure is much lower than atmospheric press... | [
"The inside and outside pressures won't be the same, since the surface tension of the (spherical) bubble wall tends to pull the bubble smaller. The inside pressure needs to be slightly higher to counter that.",
"If the outside pressure is higher, the bubble will contract, but this increases the inside pressure un... | [
"You couldn't have a vacuum, but (unless the bubble pops) there'll always be just enough pressure inside to overcome the surface tension -",
"So the bubble is self-regulating.",
"I couldn't find any videos of soap bubbles in low pressure, but marshmallows are made of zillions of tiny bubbles: ",
"https://yout... |
[
"Why are certain variables reused for different physical properties in Physics?"
] | [
false
] | I just got through with capacitance and charges section of my physics class (where sigma is the current density) and the current, resistance and emf section also has sigma, but it represents conductivity. I just thought of another one too: electric dipole moment and momentum are both denoted with a "p" as well. Are ... | [
"Short answer: There's only so many letters out there."
] | [
"And equations like:",
"⌂ = ₪",
" - ☺ (♫ / ╗)",
"would look kind of silly."
] | [
"Occasionally other alphabets are introduced: ",
"Aleph number",
". But, in general, there's enough symbols in latin+greek for there to not be too much confusion, if we started using more alphabets we'd have to learn a lot more symbols and wouldn't really gain much from it."
] |
[
"Is it wrong to say that evolution is a FACT?"
] | [
false
] | null | [
"There is the fact of evolution, and then there is the theory of evolution.",
"The fact is that there exists (and is observable) change in allele frequencies in populations over time.",
"The modern theory of evolution is that all life on earth has come from a common ancestor through decent with variation, throu... | [
"Technically nothing in science is fact. Some things are just closer than others; gravity, nuclear decay, evolution... If you want to be exacting you can say it is theory which is supported by an abundance of evidence, in fact there is no evidence that evolution is wrong (which would disprove the theory). Where peo... | [
"Technically yes; evolution is a theory that explains many facts we have observed in nature in the same sense that the theory of gravity explains the movement of celestial bodies. It isn't a fact because the idea can be subject to corrections, just like Newtonian gravity was \"replaced\" by general relativity, whic... |
[
"I am teaching an Engineering Camp, need ideas!"
] | [
false
] | null | [
"The \"simple calculations\" part makes this tricky, but here are several vibration/resonance ideas:",
"Coupled Metronome Synchronisation",
"Pendulum Waves",
" - maybe simplify it to 4 or 5, and have them predict how long until they all line up again (least common multiple of each pendulum's period)",
"Diff... | [
"Like that one Mythbusters episode, you can simulate the collapse of the Tacoma Narrows Bridge by tuning some resonator to the natural frequency of some model bridge. The kids can use simple beam equations to figure out the resonant frequency and then try to collapse the bridge."
] | [
"You can show the different natural frequencies objects have, including adding a weight to show how it changes.",
"Small buildings to show how an earthquake would travel to the top floor.",
"Check out some of the towers in dubai. They have large pools or giant spheres in the building to dampen any earthquake or... |
[
"Why are radioactive elements that only give off alpha radiation still dangerous, given that that's just a helium nucleus?"
] | [
false
] | [deleted] | [
"What I'd like to add here is that yes it's a nucleus, but a nucleus that will do almost ANYTHING to gain 2 electrons. This is what's so dangerous alpha radiation. They will rip electrons of any other molecule they come in contact with, and if that's your cell, it will do heavy damage."
] | [
"What I'd like to add here is that yes it's a nucleus, but a nucleus that will do almost ANYTHING to gain 2 electrons. This is what's so dangerous alpha radiation. They will rip electrons of any other molecule they come in contact with, and if that's your cell, it will do heavy damage."
] | [
"The problems begin when there is LOTS of alpha radiation.",
"Asking how many nuclei it takes to harm a cell is tricky. It depends what, where and when it gets hit... ",
"The relative biological effectiveness of alpha radiation is 20, compared to 1 for beta and gamma radiation. One alpha particle can be thought... |
[
"Why does a small fire look so different?"
] | [
false
] | I just came across and asked myself why it's so obvious that this is a miniature camp fire. Shouldn't fire look the same in every size as it is just energy? Or has this to do with burning gas being twirled around in the air? Thanks! | [
"The heat of a fire causes convection, an upward flow of the surrounding air. A bigger fire generates more heat, so the velocity of the flow is higher. If the velocity is higher, the ",
"Reynolds number",
" is higher. When the Reynolds number becomes larger than a certain number, the flow becomes turbulent, whi... | [
"Pretty sure it's a similar reason to why water looks so different in small scale. The size/volume is important because different properties scale differently, e.g. mass scales according to volume (size",
" ), surface tension/interactions scale with surface area (size",
" ). Therefore you have optimal sizes for... | [
"I think what may be happening here, although I am no expert, is that when you have combustion, the products produced (C02,H2O and heat energy) in a small fire are in much smaller volume than that of their larger counterparts.",
"In effect, a large flame \"dances\" because there are substantially larger and more ... |
[
"Does putting ice on a burn help the actual wound or is that done just to numb the pain?"
] | [
false
] | Would the burn a couple of days later be worse if I didnt put ice on it? | [
"How would it damage the skin when its cooling down the burn area faster?"
] | [
"I don't know the specifics, as i am not a doctor. But i would guess that it just \"kills the skin\" by cooling instead of heating. One could then argue that \"more cold for a shorter amount of time\" could allow for the use of ice, but you would still expose some of the skin to very cold temperatures, affecting th... | [
"So what your saying is that it cool some skin fast then while its cooling more skin the all ready cool skin becomes too cold and becomes basically freezer burnt."
] |
[
"Why do turtles move so slow?"
] | [
false
] | null | [
"I always wonder what happens when we suddenly get things like 3 people in one week asking about turtle speeds, because another similar post came in. Did I miss a highly publicized turtle race? ",
"Let us know if you have any more questions! The panelist who wrote that response really likes turtles."
] | [
"This question was actually ",
"just answered",
" a few days ago! Enjoy!"
] | [
"Thank you!"
] |
[
"Why did Schrodinger put a cat in his hypothetical box?"
] | [
false
] | It's always troubled me, because surely the cat is itself an observer. The cat knows whether it's alive or dead so it seems it would only ever be in one state. Why not have a simple piece of machinery, like a clock? (Of course you'd need to replace the poison gas with some other means effective against clocks) | [
"The point of the thought experiment was \"",
" this theory of how quantum mechanics works were correct, ",
" my hypothetical cat would be both alive and dead at the same time. Since a cat cannot be both alive and dead at the same time, this theory of how quantum mechanics works is therefore not correct.\"",
... | [
"Considering whether something\"counts as an observer\" or not, is really another way of saying that brains are somehow special. To suggest that a waveform objectively is, or isn't, collapsed at a given moment, is not quite right. It all comes a little clearer if we only talk about physical states of affairs ",
"... | [
"The term \"observer\" in quantum physics does not imply or require consciousness. A clock is no more or less of an observer than a cat or a human."
] |
[
"Is it possible to medically erase memories from the human brain? Either a wholesale wipe or selectively?"
] | [
false
] | [deleted] | [
"\"Wholesale wipe\" - yes, it's better known as brain damage",
"\"Selectively\" - science fiction"
] | [
"It's being looked into.",
"\nIt's a long read, though."
] | [
"No. \"Eternal Sunshine of the Spotless Mind\" was a great movie, though. "
] |
[
"How do I become a scientist? Am I too late?"
] | [
false
] | null | [
"well first off your 19, not a '20something'",
"But I'm still willing to help, you've done a good job actually graduating from highschool. Now your next step into science should be to check your local university for the related course you want. Most likely you will need to either upgrade some classes or fulfill p... | [
"A common path is:",
"Congratulations, you're a scientist! If academia turns out not to be for you, you can take your qualifications and do research in an industrial setting instead, such as people who research new medicines for pharmaceutical companies."
] | [
"Talk to the university you want to go to. You may have to do some upgrading but people older than you have made the decision to improve themselves. Don't give up on this."
] |
[
"Why do humans have a want for material desires in relation to evolution."
] | [
false
] | Me and my friend have gotten into an argument, he claims that having a desire for something that you don't "need" to have (such as an ipad), doesn't fall under a characteristic of life. But I disagree, I say that having the desire of something that isn't needed, is simply humans using intellect, which (intellect) is hu... | [
"Both of you would probably admit that you judge people by how they dress. Also, you would think of an iPad-owning person as richer than someone who does their work on an older laptop.",
"This is because by owning stuff, people signal their environment, and most want to signal that they are near the top and not t... | [
"Because our entire evolutionary purpose is to reproduce.\nTo reproduce we need a mate (and this is where fashion comes from/why it is \"important\") and material goods show wealth, so often wanting something material such as a ring is so we can show possible mates that we can provide or to show off to competitors ... | [
"well, one thing to point out to people confused over evolution is to ask them if they understand it, because if they say they don't actually believe in it that is where the problem lies. If he does understand/believe then he must uderstand that anything and everything that exists is a result of evolution. Though n... |
[
"Whats the usefulness of finding new bigger prime numbers?"
] | [
false
] | null | [
"Probably the most useful thing is the experience we gain in the hunt for the prime number. Writing programs to search for large primes is not trivial. Consider that the latest prime number is 23 million digits long. To store the number in its entirety takes about 10 Mb. People have to develop new algorithms to eff... | [
"There's virtually no mathematical point to finding the actual primes. I say this as a number theorist. ",
"Finding new large primes is mostly a computer science pursuit. What may be of actual interest is any new methods for finding primes, new optimizations to existing algorithms, or just faster computer hardwar... | [
"I would add that new, bigger prime numbers are mostly useful because they are new, not because they are bigger. The smaller ones have just been easier to find."
] |
[
"What if someone put a modern cpu, running an algorithm to generate random (pseudo) 0's & 1's, into a huge magnetic field (~15 Tesla)? What would happen to the output? How does it relates to the design of the processor (like what specific area creates this sequence and how it would be affected)?"
] | [
false
] | [deleted] | [
"There is no \"randomness generator unit\" in the computer. The CPU is running a program, like any other program; the one you are talking about just happens to have an algorithm to generate a sequence of ",
" numbers, i.e., a deterministic sequence of numbers that will pass statistical tests for randomness over ... | [
"To be fair, there do exist \"randomness generator units\" for computers usually in high encryption applications."
] | [
"It would error out and crash, ceasing the random number generation."
] |
[
"Will a cold can of soda(5°C) standing outside(30°C) reach exactly 30°C or less?"
] | [
false
] | [deleted] | [
"Entropy states that the thermal energy tends to flow to the colder region. In reality given enough time, the temperature of the can would fluctuate between hotter and colder than the surrounding air."
] | [
"Entropy states that the thermal energy tends to flow to the colder region. In reality given enough time, the temperature of the can would fluctuate between hotter and colder than the surrounding air."
] | [
"If you assume the air remains a steady temperature at 30C (with energy being put into the system to maintain the air at 30 C) then the can of soda will come to equilibrium at exactly 30C. ",
"If air at 30C and the soda at 5C are put into a small temperature shielding box, then the air and the soda will come to e... |
[
"How does string theory \"connect\" the differences between general relativity and quanum mechanics?"
] | [
false
] | [deleted] | [
"ok, first of all, let's talk about the common misconception that quantum mechanics refers to the \"very small\", or that there is a ",
" scale at which quantum mechanics holds. This isn't true and cannot be: quantum mechanics has only one fundamental constant, Planck's constant, and it just does not have units o... | [
"This is why I chose to post here, thank you for the in-depth answer!",
"Be wary of ELI5. Lots of people reread \"explain to me like I'm 5\" as \"I'll explain to you like ",
" am 5\", in other words they make up shit. In my experience many physics answers in eli5 are just random wrong stuff. There is no quality... | [
"This is why I chose to post here, thank you for the in-depth answer!",
"Be wary of ELI5. Lots of people reread \"explain to me like I'm 5\" as \"I'll explain to you like ",
" am 5\", in other words they make up shit. In my experience many physics answers in eli5 are just random wrong stuff. There is no quality... |
[
"There seems to be a small pocket of air inside chicken eggs. What gas or gases make up this air pocket?"
] | [
false
] | Also, I'm not sure what flair to tag this with. | [
"This is called the air cell. When an egg is laid the aircell is tiny or not present and as the egg cools and loses moisture the cell grows. This happens because eggshells are porous and air enters to make up the space from the lost volume of the egg contents.",
"It's mostly just air. So the gases are 78% nitroge... | [
"Neato, I didn't even consider that the air came in externally. I imagined it as a biological byproduct of whatever goes on inside the shell while it's being formed."
] | [
"Most people aren't aware of this type of transport mechanism. We tend to think (in common-sense terms) that solids are impermeable. In reality, even the densest of materials (metals) are permeable to other things on a large-time scale. If you put two pieces of any metal together, they will eventually exchange a... |
[
"How do I determine the amount of calories in an object? eg. a Boeing 747"
] | [
false
] | [deleted] | [
"An object like a Boeing 747 is more than just a loose collection of molecules -- it is a collection of atoms and molecules that are chemically bonded to each other. That means that, due to ",
"binding energy",
", their potential chemical energy as a whole is different from what you would get if you considered ... | [
"I don't think it's that hard. It's just a sum of the parts. If you want to make sure to get every single part, then it's a tedious process. But just using the big parts, you'll get a decent approximation.",
"If you know the plane is 20% fuel by weight, then you can just look up the calorific value of that much f... | [
"Generally to find the calories in a complex object you would have to burn all of it in an enclosed vessel, such as a bomb calorimeter. You then measure very precisely the changes in temperature etc. Calculating this theoretically would be very difficult as there are many different materials bonded together. "
] |
[
"A question in regards to the Grunenthal scandal from the 1950s and 60s..."
] | [
false
] | null | [
"This question is about science policy, not actual science. As such, I'd recommend you post on a subreddit better suited for that type of discussion. All the best!"
] | [
"I see. Where would I find this sort of subreddit?"
] | [
"Unfortunately this is where I'm probably going to be less than helpful. I suppose you could try ",
"/r/politics",
", ",
"/r/AskReddit",
", ",
"/r/scientists",
", ",
"/r/pharmacy",
", or ",
"/r/medicine",
"."
] |
[
"How does our body regenerate blood cells?"
] | [
false
] | [deleted] | [
"Blood cells, both red, and white are constantly being produced.",
"cells know as pluripotent hemepoietic stem cells divide (these are found in your bone marrow and to a lesser extent liver and kidney, and spleen), in the process they replenish their own populations as well as giving rise to the various progenito... | [
"Layman version: The source of red blood cells is bone marrow (cells that occupy the inner cavity of bones), in adults the primary sites of blood cell generation are in the ",
" vertebrae, sternum, and ribs",
" In children, the marrow is more active in the long bones",
" There are many ways your body is abl... | [
"actually in the adult most production of blood is in the pelvis, calvarium (skull (hence frontal bossing in the thalassemias)), the sternum, and then some minimal production in the diaphysis of some long bones... In children production is more in long bones, and in the fetus hematapoiesis takes place predominantl... |
[
"Do we know or have a estimate of the next system Voyager 1 will enter and how long it will take?"
] | [
false
] | Since plotting and projecting is so common in astronomy that someone would have taken the time to make the calculations. | [
"If Voyager were heading straight to the closest system, it wouldn't arrive for around 60,000 years. As it is now, it won't even get past the Oort Cloud, which is part of our Solar System, for 15,000 years or so. ",
"Voyager isn't headed to the nearest solar system, so it'll be much longer than that. ",
"Space ... | [
"Here is a nice article on Space.com",
" that answers this question better than I could!"
] | [
"The term \"flyby\" doesn't really seem appropriate for something that only gets within 1.7 light years of a star. It'll hardly be 1.7 light years away from the sun by then. Real answer seems to be that voyager isn't going to enter any other systems."
] |
[
"Does the periodic table of elements go on forever? Is it possible to synthesize element 1,000,000?"
] | [
false
] | I understand that some elements have only been synthesized in a lab and last for mere fractions of a second, but is there anything keeping us from creating, for example, element 1,000,000 even if it only lasted for an incredibly short period of time? | [
"Most likely not. The IUPAC defines a chemical element as a nuclear species with a given atomic number which has at least one isotope with a lifetime exceeding around 10",
" seconds. This is the characteristic time scale of the \"motion\" of atomic electrons. So if the nucleus doesn't live at least this long, it ... | [
"I certainly don't consider a neutron star to be an atom, or even a nucleus. It's closer to what we call \"infinite nuclear matter\". In reality it's a gravitationally bound system rather than a system bound by the nuclear force.",
"Maybe the IUPAC has a technical definition for \"atom\" as well, but I'd just say... | [
"I'm aware of that, but that doesn't really answer the question. And furthermore these nuclides are unlikely to be stable; their half lives are probably on the order of milliseconds or so."
] |
[
"How is that plastic micro particles can enter the bloodstream? Aren’t they too large?"
] | [
false
] | Recently found micro plastics in the human bloodstream for the first time. I can understand finding plastic chemicals and compounds in blood, but aren’t actual particles too big to pass? We must ingest or breath all sorts of countless fine particles daily. Yet do those pass into our bloodstream too? | [
"Ingesting, eating and breathing in plastics are the initial step. ",
"Next steps could be localized or body wide. During digestion intestines absorb nutrients, this could be (and most likely is most common) way plastics build up in bodies. Secondly, lungs and really any body part that requires oxygen (all body p... | [
"Yes, that all makes sense, and explains how chemical compounds and molecules enter the bloodstream, but something as large as an actual particle which I would imagine are orders of magnitude times larger then oxygen molecules, and other nutrient molecules. I’m making a lot of assumptions, hence why I’m asking, but... | [
"Red blood cells are 7-8 micrometers. Some of the smallest microplastics are 700nm. SIGNIFICANTLY smaller than RBC. ",
"Now to address the plastics question: all plastics are polymers, not all polymers are plastics.",
"What is a compound?",
"A compound consists of two or more elements that have a bond.",
"W... |
[
"Are there any living beings that can only be seen outside of our visible spectrum of light?"
] | [
false
] | [deleted] | [
"What a great answer. I would add that the entire field of ",
"contrast microscopy",
" has arisen to address the challenges of imaging transparent samples."
] | [
"What a great answer. I would add that the entire field of ",
"contrast microscopy",
" has arisen to address the challenges of imaging transparent samples."
] | [
"I'll chime in with some physics perspective, but remember that being completely invisible is extemely hard even for non living beings. Even if a material is transparent, as light is an electromagnetic wave, as it enters any material it interacts with the particles inside which results in a slowed velocity. Because... |
[
"According to an outside observer, does a beam of light shined directly at a black hole ever cross the event horizon?"
] | [
false
] | Or does it slow down as it approaches it, just like massive objects? If it does slow down, could someone please explain how this is consistent with the constancy of the speed of light? | [
"I'm trying to figure out how to translate this from maths to English for you.",
"The radial component of the line element, ",
" is a function of the gravitational field and of radial position, ",
" Specifically, it's (doing this from memory, so somebody correct me if I drop a sign or something) ",
" = ",
... | [
"This is a fairly famous thought experiment involving a convergent series of partially silvered mirrors strung along a radial vector.",
"The short version of the answer is that as the light scatters off each mirror, what comes back to the distant observer is more and more red-shifted, tending toward infinite reds... | [
"TL; DR: No. Also remember that both time and space change in sync.",
"No, an observer away from the black hole never observes it cross the event horizon. Of course, you never ",
" see a light ray cross any given point either. But that's not what you mean. To usefully talk about this we have to go quite a b... |
[
"What would happen to an astronaut if one of his limbs was exposed in space?"
] | [
false
] | [deleted] | [
"He would get a terrible, terrible sunburn. If he left the arm exposed longer, the high energy radiation would probably give him skin cancer in that area later in life, along with enhancing the possibility of other forms of cancer elsewhere in his body. It is a common misconception that space is so cold it would ... | [
"Wouldn't the gasses in his blood and cells start to boil? Kind of like the bends but more extreme?"
] | [
"No, the blood wouldn't boil."
] |
[
"Quantum tunneling, and conservation of energy"
] | [
false
] | Say we have a particle of energy E that is bound in a finite square well of depth V. Say E < V (it's a bound state). There's a small, non-zero probability of finding the particle outside the finite square well. Any particle outside the well would have energy V > E. How does QM conserve energy if the total energy of the... | [
"The Schrodinger equation is just a ",
"conservation of energy equation",
". So, any wave function that satisfies Schrodinger's equation must necessarily conserve energy. The wave function for the finite square well most certainly conserve energy, as we find the wave function by solving Schrodinger's equation."... | [
"The particle doesn't gain any energy when it tunnels. What we mean by quantum tunneling is when a particle surpasses a barrier that it could not surpass classically. ",
"If I am bound in a finite square well of depth V<E, ",
", I don't have anything to tunnel through. If, on the other hand, there is \"room\" o... | [
"The uncertainty principle guarentees that if you are found within the barrier (thus a delta x given by the barrier width) that the uncertainty in you energy is large enough that you cannot ensure that it was lower than the barrier height. Thus, the uncertainty principle prevents you from \"catching\" a particle so... |
[
"How do you describe refraction through quantum mechanics?"
] | [
false
] | Also, I've heard of the experiments in UC Berkeley in which they slowed down the speed of light to 9.7km/s. Was this 'slowing down' the speed at which the light travelled, or only the speed? | [
"They didn't slow down the ",
", if that's what you're wondering. They used tricks to slow down the transmission of light in a semiconductor. Wikipedia's article on slow light will tell you so ;)",
"But yes, the light actually traveled at 9.7 km/s. ",
"At Harvard, researchers managed to actually ",
" a l... | [
"Richard Feynman on Quantum Mechanics",
"Part 1: Photons: Corpuscles of light (1h17m)",
"Part 2: Reflection and quantum behavior (1h38m)",
"They are long, and really worth it. It's Feynman. Refraction can be explained with the box with a mirror in it, which is in part2 around 28 minutes in."
] | [
"Well, in a sense, it's a question that's impossible to answer. Once you get down to the quantum scale, it's literally impossible to know what a single photon is doing between interactions.",
"But if you zoom out, so to speak, and stop thinking about photons but rather the whole beam of light as a wave phenomenon... |
[
"How long would it take for a running faucet to erode through a ceramic sink?"
] | [
false
] | Let's say it's running at full blast and it's a regular-sized sink (and ceramic because it's a usual bathroom material). Would it be something like a couple years of continuous running, or on the order of hundreds of years? | [
"Depends on the water. If it has a high calcium or silicon content and is hotter than ambient, then mineral deposition could actually achieve the exact opposite - filling in the entire basin with hard mineral deposits known as ",
"calcareous or siliceous sinter",
". This often happens around hot springs, for ... | [
"I don't know if you intended your question to be slightly demeaning, but I can totally see why the guy might think the sink would break in half like that:",
"Both of those situations beg application of the scientific method, and these types of questions are smart ones because it demonstrates curiosity and desire... | [
"Erosion at Niagara Falls is in no way comparable. ",
"Erosion at waterfalls",
" mainly occurs by undercutting and resulting headward erosion. The water preferentially erodes weak layers at the base of the falls and the overlying layers, lacking support, collapse and the broken material is removed."
] |
[
"What parts of the human body that we are born with are never lost/replaced?"
] | [
false
] | I'm thinking at the cellular/structural level. Cells on the epidermis die and are sloughed off, thus being recycled, but what parts of the body are opposite to this, i.e. never being recycled? | [
"Nerve cells,Cartilage, and eggs cells in females"
] | [
"Even in non-proliferating tissues such as the ones you pointed out there still is biochemical turnover. With mutations and repair even the DNA in those cells would undergo changes. The lower you dive into structural levels the harder it is to find actual constants."
] | [
"By that definition, there will never be a cell that doesn't 100% ever get modified or get lost. I was talking about cells that aren't replaced mostly. All cells will eventually die."
] |
[
"In simple terms, how did Einstein prove relativity and that time experienced by body would be less if it travels near the speed of light?"
] | [
false
] | null | [
"Here's what happened historically:",
"First, we have \"classical\" physics. Thanks to Newton and his successors, we have some equations of motion that describe reality extremely well. One interesting thing about these equations is that if you give all of your objects the same velocity boost, it all cancels out a... | [
"You mean muons, right? "
] | [
"It's all correct, but you don't mention any proofs, which was OPs question.",
"Einstein didn't prove it himself. But the first proof is myons. Myons decay after while. Cosmic radiation produces myons in the upper atmosphere. But at the speed they are travelling, they shouldn't be able to reach the ground. Or at ... |
[
"Can you effectively wash your hands with cold water and old-fashioned (not antibacterial) soap?"
] | [
false
] | Just curious whether cold or lukewarm water negatively affects the effectiveness of hand-washing in the absence of antibacterial soap. If so, what temperature is required for maximum efficiency while remaining tolerable for your skin? | [
"Yes, and in fact traditional hand-washing with normal soap is actually seen as ideal by modern public health officials. As far as I know, temperature has a negligible effect on handwashing, as the time that the water has contact with your skin is negligible, if you're thinking about it in terms of killing the bact... | [
"Source, which cites reputable sources:\n",
"http://health.howstuffworks.com/skin-care/cleansing/basics/hand-washing2.htm",
"google search that led to above link: Water temperature and hand washing",
"Yes, you can effectively wash hands with cold water and normal soap. The positive effects of handwashing come... | [
"The fats and dry matter that you want to remove, reacts with the caustic effects of the soap. This means that the base negative charged hydroxide ions of the soap attracts the positively charged oxonium ions of the dirt, and thus breaks the bonds that has formed and makes the structure of the dirt. The water acts ... |
[
"If you had a chamber with propane at 2000 deg F, and you introduced table salt, would you get any Na2O?"
] | [
false
] | Reference for salt reactions in a carbon combustion environment: | [
"Given that the combustion of propane produces water vapour, it seems entirely reasonable to assume so. As the wikipedia article says, the NaCl gas reacts with water in the air to form sodium hydroxide and decomposes to give sodium oxide.",
"Something to bare in mind is that on exposure to air with moisture in i... | [
"What if there is almost no air, and very little combustion, as in pyrolysis conditions?",
"To clarify, I'm going to hook up a propane tank to an electric kiln and flood it as I heat it up to 2000F. Then I am going to let some air in and throw in table salt. It makes gorgeous pottery finishes."
] | [
"Assuming no air, only propane and salt (assuming pure sodium) you would get no sodium oxide as there are no oxygen molecules present. As soon as you add air, you have oxygen molecules that changes the game. Then you get H20, C02, CO, Na2O, NaOH all as products plus other trace molecules. I'd have to run the simula... |
[
"Why can't we make an artificial heart that lasts a very long time?"
] | [
false
] | I know there are artificial hearts, but why are they only a temporary solution? Shouldn't the technology be there to make a very good, maybe even better heart? | [
"Shouldn't the technology be there to make a very good, maybe even better heart?",
"Well, the answer is simply no. There's no rule that technology should be that good.",
"To fully replace a heart, you need a small, extremely durable machine capable of repeatedly performing a fairly energetic task for many years... | [
"Along with this, the artificial heart has to be able to react appropriately to different requirements, such as beating faster when the person is phtsiy active to provide enough oxygen to the body. "
] | [
"Also blood clots. This isn't a problem with your heart since it's designed to prevent blood clotting. But with an artificial heart, any points of stagnation or grooves etc is going to create an embolism. That is a very bad thing.",
"Our biomaterials and pump designs just aren't quite good enough yet either."
] |
[
"How close are we to finding a cure to the Common Cold? What's the 'official' steps in finding/confirming a cure?"
] | [
false
] | [deleted] | [
"I'm going to be pessimistic and say, not very close. The common cold is not the result of one virus. There are hundreds of different viruses that can cause it. So if you want to cure it, you need to find a way to stop every one of those viruses.",
"In general, there are two strategies that are used to find cures... | [
"The problem is that there's no such thing as 'the common cold,' that's just what we call any low-level infection which doesn't kill you and gets cleared in a reasonable time frame. ",
"We could eventually work up a vaccine to any one particular virus, but there are so many of them mutating so quickly that it wo... | [
"In terms of ever finding a cure for the \"common cold\"....",
"Hahaha not even close (though this last winter was pretty good to us) ",
"There are just too many viruses that can cause the common cold (over 200). Sometimes we have a better guess at what the kid has based on other symptoms, GI problems we thin... |
[
"Is there a Super Massive Black Hole at the center of EVERY galaxy?"
] | [
false
] | I have read several obscure science articles describing the probability but none state it definitively. I know scientist say their is a super massive at the center of the milky way. I have been wondering if true why. | [
"Probably not.",
"Small irregular galaxies may not have central black holes, though they could just have relatively low mass ones we haven't detected.",
"A2261-BCG is a (very) large galaxy that appears to lack a central SMBH. It's theorised the black hole formed but was later ejected in a galactic merger.",
"... | [
"How would a spherical, non-rotating galaxy maintain it's shape? Shouldn't gravity cause it to collapse inward if it isn't spinning?"
] | [
"How would a spherical, non-rotating galaxy maintain it's shape? Shouldn't gravity cause it to collapse inward if it isn't spinning?"
] |
[
"What happening when/why do we 'zone out'?"
] | [
false
] | I don't really know how to explain 'zoning out' if you don't know what I mean--probably the best example is when you're and somebody who sees that will probably wave their hand in front of you. Anyway, is it just us acting stupid for a minute or is there some kind of neurological 'hiccup' going on? | [
"Your brain devotes huge amounts of energy to \"filtering out\" information that it finds irrelevant. For example, at any given time you usually don't feel the clothes on your skin, you don't pay attention to all the sounds around you etc. If you did you would go crazy dealing with sensory overload. ",
"My guess ... | [
"Well, as a kid with ADD, I frequently zone out when I'm bored. ",
"http://discovermagazine.com/2009/jul-aug/15-brain-stop-paying-attention-zoning-out-crucial-mental-state",
" implies that it's related to daydreaming. But still, there is some difference between the two"
] | [
"Microsleep"
] |
[
"If a living organism, say a cell for example, is composed of a combination of tinier living compounds, which is then made up of smaller non-living matter--Would it be possible to re-create that same living organism using a combination of non-living matter?"
] | [
false
] | null | [
"I'm not quite sure what the paragraph is trying to say, but it is certainly possible to create life from \"dead\" components. Life is but a series of (complex!) chemical reactions.",
"One way of looking at it is human reproduction. How is babby formed?! Literally, the mum is eating the building blocks for that b... | [
"By and large the smallest organisational unit which can be said to be alive is a cell (putting the virus argument aside for a moment). Cells are composed of a wide variety of compoments, almost all of which are complex organic molecules, these include lipids (fats), proteins and enzymes, DNA and many more...",
... | [
"This is a philosophical question, IMO. For arguments sake, if we had perfect knowledge of how individual atoms come together to yield the emergent phenomena we call consciousness, in addition to the requisite bodily functions needed for life, then the answer to your question is maybe?"
] |
[
"How do we determine sea level?"
] | [
false
] | Do we base it off of some point on land, and then depending on if it raises or lowers from that point we know if the sea is rising? And if that is how we do it, do we measure that point at high or low tide? Also, how often do we change topography maps with the new sea level? | [
"There are two main ways to determine sea level. \nFirst, is to do the whole geoid math that ",
"/u/ToasterFanclub",
" mentioned. The other way is to take an hourly, 19-year average of tide levels and use that mega-average as sea level. This second way is used in aviation, atmospheric sciences, and land surveyi... | [
"Yes, over water that would be the better, and rereading the OP, this would be the better answer"
] | [
"Short answer. It would be based on the geoid. It would be the height of where the water would be if that pesky land wasn't in the way. ",
"Longer answer explaining the geoid and how it affects what level the water would be:",
"Start off with a stationary ideal planet. Gravity would pull everything in and make ... |
[
"James Webb Space Telescope question."
] | [
false
] | Someone told me that this telescope, when deployed, will actually be able to observe exoplanets; not just their gravitational pull on stars, or dark spots, but it will be able to take images of planets in other solar systems. Is this true? I haven't been able to scrape up any information on this claim. | [
"We have already taken pictures of planets around other stars, most notably this star: ",
"http://en.wikipedia.org/wiki/HR_8799",
" "
] | [
"http://en.wikipedia.org/wiki/New_Worlds_Mission#Starshade"
] | [
"So will the JW be able to produce better photos than this? Does anyone know by what order of magnitude better?"
] |
[
"Does Epsom salt actually do anything?"
] | [
false
] | [deleted] | [
"Chemistry student with a dash of pharmacology education here:",
"Your skin is capable of absorbing compounds, but the actual ",
" is likely to be low. High enough for therapeutic effects? I don't know.",
"Drugs are introduced into a cell via a number of routes: passive diffusion, facilitated diffusion, or ac... | [
"Both of those studies are highly biased, don't you think?"
] | [
"The second one may be. Although the first one is on a site promoting the benefits of magnesium, the study is produced independently by the University of Birmingham. "
] |
[
"Do scale-prevention devices based on quartz crystals work? If so, what is the scientific basis?"
] | [
false
] | I've come across this product called that claims to prevent scale buildup, using nothing but quartz crystals. Electricity is not provided, the quartz just sits there. Quartz crystals, allegedly, "emit low end frequencies" which break up scale and prevent it from forming. It sounds like pseudoscientific nonsense to me, ... | [
"quartz is piezoelectric, but it won't oscillate unless there is oscillating voltage applied or it is part of an oscillator circuit. The amplitude of motion for a tiny crystal is very tiny. The frequency of the crystal goes up with decreasing size, so tiny crystals oscillate at very high frequencies, not low. In fa... | [
"In fact, typically megahertz frequencies, not acoustic frequencies, so its not \"sound waves\"",
"Just want to correct this. Even if the frequencies are high above the maximum frequency of human hearing they are still \"Sound Waves\" according to the acoustics definition. Acousticians do categorize sound waves a... | [
"Unfortunately, getting a voltage from dissimilar metals only works if there is a temperature gradient - gotta love the Seebeck effect. Columbium is right, quartz crystals (when voltages are applied) operate at relatively high frequencies - I've never seen one below about 20KHz. Looking at their website, I find mys... |
[
"What is the relationship between gravity and magnetism?"
] | [
false
] | null | [
"This is a totally unanswered question in physics, and an extremely important one too.",
"Right now, the consensus in physics is that there are four fundamental forces: electromagnetism, weak nuclear force, strong nuclear force, and gravity. The standard model of particle physics accounts for only the first three... | [
"thanks. I was just about to ask if there was any progress on the topic"
] | [
"thanks. I was just about to ask if there was any progress on the topic"
] |
[
"What are the main differences/similarities between Gram positive and Gram negative bacteria?"
] | [
false
] | First time poster long time lurker. I recently went on a bit of a Wiki dive when looking at Petrichor, and found out about actinobacteria and the Gram test, but I can't quite discern from looking at the two wikis the differences and similarities of what Gram Positive and Negative bacteria have. I am not a scientist in ... | [
"The main difference is their cell wall/cell envelope structure. Both gram positive and negative have an internal cytoplasmic membrane surrounded by a peptidoglycan layer (cell wall). The peptidoglycan is much thicker in gram positive bacteria, but gram negative bacteria also have an outer membrane surrounding the ... | [
"Another difference between them is that the membrane of gram negative bacteria is generally more complex than that of gram positive. "
] | [
"I believe so, I remember reading it, im not a biologist by any means, but I took A.P bio and learned a decent amount. "
] |
[
"Why do lines come out of light sources when you squint?"
] | [
false
] | My best guess is that it is coming from something about my eye-lens shape being changed. | [
"I'm trying to remember the exact term for this, but it's the same effect that you see in cameras. Essentially, when you squint, you are changing the shape of the \"aperture\" for your eye, and the number of streaks and the shape of the streaks depends on the shape of the aperture.\nFor cameras, you have an octagon... | [
"I've always kind of thought it might just be how the light shows through your eyelashes, but I'm glad you asked because I've been really curious too."
] | [
"By closing your eyelids just until the lashes mesh without completely closing the lids."
] |
[
"Question about an alien spaceship travelling to earth"
] | [
false
] | I had a discussion about it and now am rather confused. Following situation: An alien planet is 10'000 lightyears (LY) from earth. So at our year 0, they receive the radiowaves from year -10'000. An alien ship launches and travels to earth with lightspeed (if this is a problem, let's say 99.9%) just as the radiowave fr... | [
"Now as the ship travels the 10'000 years to earth, does it receive 20'000 years worth of radiowaves? How?",
"Yes. It will be doppler shifted, though. So not only are the frequencies higher, everything is played in fast forward, so to say. Time dilation also comes into play. The closer the aliens get to the speed... | [
"It might actually heat up the spaceship quite a bit, yes. "
] | [
"The ship spends 10000 years in transit but at the same time it is crossing radio waves going the other way. It crosses 20000 years of radio waves."
] |
[
"What would happen if the Sun suddenly disappeared...?"
] | [
false
] | (The Sun disappear suddenly and instead there is only space). Specially interested in: How long would be until the temperatures on Earth made human living impossible? Could some living beings (like extremophyles on hydrothermal vent) survive? What would happen to the orbits of the planets? | [
"We would have about 8 more minutes of light.",
"But way more interesting to me is that we would have about 8 more minutes of gravitational attraction before we began to float off in a straight line. Gravity operates at the speed of light."
] | [
"For 8 minutes, nothing at all. We'd keep on orbiting and we'd still see the sun. Then... it gets bad. (speculating:) Presumably we'd fly out of the solar system on a straight path along some vector tangential to our orbit, as would all the other planets. We could quite possibly live underground, there was a thread... | [
"No, for eight minutes it would be like nothing has happened at all because, at that distance from the Sun ",
"."
] |
[
"The Human Genome Project cost $2.7 billion. 20 years later, it costs <$1000 to sequence the genome. Was the cost of the project fundamentally necessary for subsequent progress, or could we have \"waited\" for the technology to become cheaper?"
] | [
false
] | I'm very much a clueless layman, but I'm learning about genetics for the first time. I don't mean this in any sort of combative way–the Human Genome Project had countless benefits that we can't possibly track, and I'd imagine $2.7 billion is a trifle compared to its broader impact. My question is just narrowly about th... | [
"The cost of gene sequencing has dropped dramatically, but these two numbers are apples and oranges. The Human Genome Project \"mapped the genome\". Meaning it created a \"reference genome\" that is roughly accurate for every human being on earth. It's like a scaffold upon which you can place any individual sequenc... | [
"We did go through a bunch of technological leaps though. The HGP was done with Sanger sequencing and the nanopore and similar we've got today are hundreds of times cheaper per base."
] | [
"Short answer is no. Basically the people working on the Human genome project developed and advanced the technology while also proving that it was even possible! ",
"A good analogy would be that it cost about $2.27 Billion for the Sputnik mission to get the first person into space and SpaceX rockets cost about 57... |
[
"I want to create a contained \"atmosphere.\" Is this possible?"
] | [
false
] | null | [
"All of that depends on the type of experiment you are preforming, what kind of data you need, what kind of model you are making, etc.",
"Building an airtight vessel that has a gas composition of our atmosphere or close to it is pretty simple, but things get complicated pretty fast. Do you need to analyze the ga... | [
"Thank you, this is helpful.\nI definitely would want to \"recreate\" the sun, I didn't realize it would require that much precision. Now that I think of it though, maybe it could work without it? I had the idea of essentially getting this \"atmosphere\" together, rising the temperature to global averages with, and... | [
"I think it really depends on what exactly you are trying to measure. If you want to measure just the raw insulation of a certain mixture of gasses then you don't necessarily need a fake sun, though you can also find this data or calculate it from known properties without running an experiment.",
"Faking the sun... |
[
"How do energy saving light bulbs work?"
] | [
false
] | null | [
"I am assuming you mean CFL's vs incandescent. ",
"In this case incandescent bulbs heat a filament enough that its blackbody radiation shifts into the visible range. Now a lot of this electricity that goes into heating dosen't make it out as visible light but instead as heat and is essentially wasted since we ca... | [
"Now kids, don't go out and break flourescent bulbs to observe this coating firsthand.",
"These bulbs contain mercury.",
"Mercury's bad, mmmmmkay?"
] | [
"yes I get the reference....but newer bulbs are mercury free ;D Yay"
] |
[
"What would space battles realistically look like in the near future?"
] | [
false
] | null | [
"Over large distances, lasers would be almost necessary. Space is really big, and lasers obviously move faster than any other weapons available."
] | [
"Depends on what you mean by \"near-future\". But I'd recommend reading about The Outer Space Treaty: via Wikipedia,",
"The Outer Space Treaty represents the basic legal framework of international space law. Among its principles, it bars States Parties to the Treaty from placing nuclear weapons or any other weapo... | [
"While that's true, the 2007 Chinese killsat test is particularly important in the context of space warfare, since China's the sort of country that might actually put this tech into use (as evidenced by their ambition, lack of stake in the current space status quo, behavior in other contexts, etc)."
] |
[
"Is a radio station's transmitter power approximately equivalent to how much power a light bulb would need to have to be visible everywhere in the radio station's listening area?"
] | [
false
] | Obviously what type of bulb and what time of day would matter a lot, but my basic question is whether a radio transmitter is essentially a giant light bulb that just generates light outside of the visible spectrum. | [
"I think that this slightly misses the point of the question, which I believe is more along the lines of \"How does a radio station's broadcast range compare to the range over which a visible light source of the same power would be visible?\""
] | [
"radio waves have a much (MUCH) ",
" frequency than light.",
"Typical visible frequency is about 5*10",
" Hz . Typical VHF 10",
" Hz which means that it has a roughly 1 million times lower frequency (and lower energy).",
"However, transmission depends on the frequency/wavelength, but it is more complicate... | [
"radio waves have a much (MUCH) ",
" frequency than light.",
"Typical visible frequency is about 5*10",
" Hz . Typical VHF 10",
" Hz which means that it has a roughly 1 million times lower frequency (and lower energy).",
"However, transmission depends on the frequency/wavelength, but it is more complicate... |
[
"Is the frequency range of human hearing limited by the biology of the ear, or brain capability/processing?"
] | [
false
] | Suppose technology were advanced enough to create a bionic ear implant, capable of interpreting frequency ranges wider than 20Hz-20kHz. Could the human brain interpret the signals and give us super hearing abilities? | [
"You can hear ultrasonics quite well by using frequency division or heterodyning systems, which are the basis of bat detectors. The basic technique is to divide the ultrasonic frequnecy by some constant to remap it onto your normal hearing range or to convert high frequencies detected into clicks to let you know t... | [
"This is in fact a combination of both. The human ear works because of sound waves will make hair cells in the cochlea move. Thus generating an electric current, which is sent to the brain where it gets \"decoded\". The cochlea wouldn't be capable of catching waves outside the 20Hz - 20kHz. That's why humans can't ... | [
"Thanks for your responses! I've learned something here. However I'm a little surprised by the conclusion from Mallasun. I suppose I jumped to the conclusion that the brain might be capable of decoding wider frequencies—given better equipment—in a similar way to how eye mutations or defects allow some people to see... |
[
"Is there a widely-accepted theory as to the characteristics of randomness?"
] | [
false
] | null | [
"The lottery is not going to be affected by quantum physics, and that's the only source of true randomness there is. The lottery numbers that are picked don't care who's buying them. The butterfly effect, and all of chaos theory, can (and usually does) occur in perfectly deterministic systems; it's just that they'r... | [
"So all of what we know as 'randomness' or chance on a macroscopic scale is only considered as such because we have no way of predicting it with perfect accuracy (or, often, with any accuracy at all), but the outcome of a given 'random' event (e.g. the rolling of a die) is essentially predetermined as soon as the a... | [
"Sure. Think about what happens when you're rolling a die: you give it some velocity in some direction, and it falls, hits the table, rolls and bounces around, all following perfectly ordinary laws of physics. Given complete knowledge of the entire system, you could predict the outcome, unrealistic though that is i... |
[
"Why can't we as a planet completely switch over to nuclear energy and shoot the radioactive waste into the Sun?"
] | [
false
] | null | [
"The two most common reasons we cant dispose of the waste in space are: ",
"Expense. Right not it's just too damn expensive to launch stuff into space, let alone to the sun. But this will come down soon.",
"Risk. If that rocket carrying it to the sun blows up in our atmosphere, well, we'd all be having a very b... | [
"Reasons for not switching to nuclear:",
"Public fear. Also from the lawmakers who implement it. People just don't trust the safety enough. Especially since the Japanese tsunami incident recently. That incident prompted a massive inspection of all reactors in Europe. Cant remember exact stats, but that majority ... | [
"So right now, we're limited by technology of space travel and the social stigma of nuclear safety. Say both of these issues are solved over time, it would, in theory, be safe to dispose of nuclear waste by shooting it at the Sun? Could all waste produced by humans be disposed of this way? "
] |
[
"If we our sun was a different type of star, emitting different types of radiation or light, would our plants be a different color?"
] | [
false
] | Just as the title reads. | [
"Well we actually evolved to see certain wavelengths of electromagnetic radiation, roughly .4-.7 micrometers. This is because the light that gets to our eyes has the highest concentration of light in that spectrum. To address your question, ALL colors would be different because we would not be seeing the same way, ... | [
"I'm going to assume you mean \"would plants have evolved to use different wavelengths of light and therefore would not be green if our sun emitted different wavelengths of light than it does now\".",
"Obviously, if you went to some other planet, or \"restarted\" evolution of this planet, plants (and animals) cou... | [
"Yes, thank you! I couldn't figure out how to word this question. That's very interesting. Thanks for the clarification!"
] |
[
"What Would Happen if the Forces Holding the Molecules in your Body Together Disappeared?"
] | [
false
] | null | [
"Hi j0nr 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 following ... | [
"Physics"
] | [
"Physics "
] |
[
"How do we know genetically modified foods are safe for human consumption?"
] | [
false
] | Taking BT corn for example. Assuming the necessary animal and human trials have been conducted to demonstrate the cry1Ac protein is safe for human consumption: This protein is 1178 AA in length, yet the gene it is encoded in is 75 Kb. That would suggest only 4.7% of this gene codes for the cry1Ac protein. How thorough... | [
"You are asking the wrong question: ",
"First the GM crops",
"The only mechanism by which DNA can harm us is by the proteins that it encodes. DNA itself can do nothing, it just gets digested. DNA is DNA no matter it's source.",
"The proteins that we want a GE organism to express are very well understood. ... | [
"You said yourself that we do not fully understand how genes and the epigenome function. This is true. Because of this, we cannot absolutely predict the effects of a given gene based on our knowledge of genetics. However, that is true for every organism. If you examined the entire genome for Bt corn, it would be eq... | [
"The testing applied to GM crops is no different than the testing applied to any other food product that comes on the market - arguably stricter for GM, actually."
] |
[
"Would a comet in a binary star system have two tails?"
] | [
false
] | It's my understanding that a comets tail is caused by solar winds, so I'm wondering if a comet interacting with solar winds from multiple stars would have multiple tails? | [
"The tails ",
" caused by solar winds, but having two star would ",
" cause there to be two tails.",
"When you have one star, the force acting on the comet's dust is basically in one direction (unless you go across vast distances), and grows weaker with distance.",
"When you have two stars, you just get two... | [
"Vectors!"
] | [
"The two tails you are seeing there are the gas (ion) tail and dust tail (larger particles), both caused by a single source.",
"Read more at Wikipedia"
] |
[
"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! ... | [
"Where does the music in my head come from? Why does it happen?"
] | [
"The fast growth of bamboo mostly doesn't come from specific genes, but rather from the structure of the plant itself and the environment it is growing in. Bamboo is a grass, and grows entirely from the tip of the shoot. Since all the growth of the plant happens at one point, it grows fast. Something like an oak... | [
"The fast growth of bamboo mostly doesn't come from specific genes, but rather from the structure of the plant itself and the environment it is growing in. Bamboo is a grass, and grows entirely from the tip of the shoot. Since all the growth of the plant happens at one point, it grows fast. Something like an oak... |
[
"Where did Earth's water come from?"
] | [
false
] | [deleted] | [
"The same reason that it's the only planet with life on it. We're the perfect distance away from the sun for the elements of life to latch on and grow! Hydrogen, oxygen, nitrogen, carbon, and other life essential elements were cooked up for billions of years in the core of a star before exploding in every direction... | [
"Earth is not the only planet with an abundance of water. There's ice on mars and moons like Europa. It has been hypothesized that there is a subsurface ocean underneath Europa due to water vapor plumes.",
"I can't say for certain what other planets have or do not have water, because I am nowhere near this field ... | [
"Different planets have different masses and different distances from the sun. Mercury is so close that most of it's atmosphere has been blasted away by the Solar wind. Saturn and Jupiter also have huge amounts of water, but they are diffused throughout a vast planetary atmoshpere so they only take up a small perce... |
[
"AskScience AMA Series: I am Tom Talbot MD MPH, an infectious diseases physician and infection prevention expert/vaccine advocate who's been working on the frontlines during the COVID pandemic. AMA!"
] | [
false
] | I am an infectious diseases physician (for almost 2 decades) working at Vanderbilt University Medical Center (VUMC - views expressed are my own and don't represent formal VUMC guidance). Much of my professional career has focused on infection prevention as the VUMC Chief Hospital Epidemiologist (a fancy word for medic... | [
"Thanks for the AMA. Two questions.",
"Has there ever been a vaccine in the past that was safe in adults but unsafe in children? I am aware of the formalin inactivated RSV vaccine from the 60s that killed a few young kids, but not sure if they were trialed in adults first to test safety. I can't find much literat... | [
"Great question -- we need to have the vaccine trials being performed in children completed (and hopefully show a similar benefit as we've seen in adults); even if not as protective, if we get more adults immune to the virus, then spread can still be slowed markedly. It's likely that the COVID virus will be with u... | [
"Great questions -",
"Off the top of my head, other than just having vaccines that have not been tested in kids, I cannot think of such a vaccine. Maybe the early pertussis vaccines that caused febrile seizures, but that was just that the infants had less tolerance for fevers vs. an adult.",
"Honestly, one of ... |
[
"Do the physical properties of ice change at different temperatures?"
] | [
false
] | Does ice change at all at different temperatures (below 0°c obviously), for example does it become in any way harder the colder it is? | [
"Under the right conditions, ice can take on different crystalline forms called \"solid phases.\" Parameters like ",
"temperature, pressure, and volume",
" govern these varying morphological regimes (image from ",
"Wikipedia:Ice/Phases",
", which features an excellent summary table). ",
"This University p... | [
"Wouldn't that suggest it does harden? Generally breaking a material involves breaking bonds, which break by absorbing too much eneegy. If there's less vibration at -70 as opposed to -10, the ice must absorb more energy overall to reach the point where bonded molecules will separate? "
] | [
"Yes it does. At least on an atomic level. Generally, atoms vibrate a little bit. They do when water is frozen at -10°C and they do when it's frozen at -100°C. The difference is that at lower temperatures, atoms vibrate a little bit less than they do at higher temperatures. At one point, they stop vibrating at all.... |
[
"If the earth spins at 1000mph, how does a rocket fly back into the atomsphere and adjust to the spin?"
] | [
false
] | So if a rocket flies head on to the earth which is rotating at 1000mph, how does it align with the rotation of the earth so that it's at at a suitable position to land? | [
"Rockets don't come straight down to land. They come in at only a few degrees of inclination away from the surface of the planet/atmosphere, moving in the same general direction as the Earth's rotation. Friction with the atmosphere then reduces their velocity until they're moving at nearly the same horizontal spe... | [
"We actually usually have sort of the opposite problem. It's rare for a spacecraft to return to Earth head on. Typically they return from orbit, and getting into orbit is not merely a matter of getting above the atmosphere but of gaining velocity. The basic concept of an orbit is that you are moving horizontally so... | [
"There's definitely more to it, but part of it has to do with the fact that when approaching earth, it's not like there's a discrete line where the atmosphere starts and that is going at 1000 mph relative to the space just outside it. The atmosphere gradually gets more and more dense as you get closer to earth, so ... |
[
"If systems move toward entropy, why do atoms tend to bond toward non-reactivity?"
] | [
false
] | [deleted] | [
"You're missing something about ",
". They lose energy when they bond, meaning that energy is given off as heat, which creates more entropy than is lost by forming a bond. The entropy of the atoms and their surroundings as a whole increases. ",
"An ",
" system moves towards greater entropy. If you bring a bun... | [
"I got the first part, but the second got me intrigued....\nCould you add ti that explanation, why would a clorine care about being in a closed or open system?"
] | [
"It doesn't 'care'. Here, ",
"see this graph",
", it's a typical representation of what the energy (vertical axis) looks like for two atoms, separated by a distance r (horizontal axis). There's a minimum, which is the bonding distance, and there's a maximal dissociation energy (D0) required to pull apart the tw... |
[
"Why is the magnetic force vector perpendicular to the magnetic field?"
] | [
false
] | [deleted] | [
"We can explain this by symmetry arguments! The force acting on a charge due to a magnetic field is a vector (like all forces) but the magnetic field is a pseudovector. Vectors change sign under a reflection transformation and pseudovectors do not. ",
"Here's an intuitive way of thinking about it. Imagine we plac... | [
"The force acting on a charge due to a magnetic field is a vector (like all forces) but the magnetic field is a pseudovector.",
"Isn't that a bit of a chicken-and-egg sort of thing? Given that explanation, aren't I going to ask, \"Well then how do you know it's a pseudovector?\"",
"We didn't find out how magnet... | [
"Magnetic fields in a different reference frame are just electric fields.",
" ",
"Consider a frame with a positive test particle moving to the left and below it, a line of positive charge moving to the right. In this frame, you can say that the test particle is deflected upwards by the combined forces of the el... |
[
"What can you do with a synchrotron that you can’t do with an electron microprobe?"
] | [
false
] | I have done some synchrotron stuff, but never use an electron microscope and am wondering more about it. I am a soil chemist and focus a lot on redox chemistry. Would it be the EXAFS are only with synchrotron but XANES can be done on a microprobe? Is it the fluorescence stuff microprobes can’t analyze? Is it a differen... | [
"Do you mean an electron microscope? The electron microprobe was developed to analyze compositions of unknown samples using wavlength dispersive xray spectrometry and an array of standard samples.",
"In a transmission electron microscope you have access to similar features in the X-ray data of a light source in t... | [
"I believe I was, thanks for the clarification! ",
"And gotcha yeah I’ll check that out, thanks!"
] | [
"To piggyback off of this, electron microscopes are ideal when you have small samples, or need to probe specific features of a sample.",
"The wavelength of an electron is 2 (if i remember correctly) orders of magnitude smaller than an xray. This means it is easier to beat diffraction limited resolution. Additiona... |
[
"Why is General Theory of Relatively needed to explain the orbit of Mercury?"
] | [
false
] | [deleted] | [
"GR is more important for Mercury than the other planets because it's much closer to the Sun, deeper in the gravitational potential where GR effects are stronger. ",
"Mercury's orbit, like the orbit of all the planets, is not circular but is eccentric. One part of it's orbit is closest to the Sun (perihelion), th... | [
"Pluto was discovered in the same way sort-of. Neptune didn't totally account for the orbit of Uranus, so some additional calculations were performed and led to the discovery of Pluto.",
"However as it turns out, the calculations were in error, making Pluto's discovery mostly a lucky fluke. They just happened t... | [
"If I remember correctly, precession does not occur for the point mass two body problem with an inverse square law. I would imagine that whatever approximation is being used by the simulation has a significant enough error so that the effective force is noticeably not inverse square law. Of course, if the simulatio... |
[
"[chemistry] Why is sunlight a mixture of all the other lights?"
] | [
false
] | So i was reading my chemistry textbook yesterday. And i came across the "Radiant Energy Spectrum". I think Neils Bohr used this to prove his atomic model theory. In the textbook it said that all elements give off a unique set colors that are part of the Light spectrum. Simply because when electrons are charged and go b... | [
"Everything you talked about is regarding atomic (or molecular) absorption and emission - and you're correct in that there are only specific allowed electronic transitions.",
"The sun, in addition to atomic emission, gives off a huge amount of ",
"black-body radiation",
", which is a different phenomenon that... | [
"I think im gonna need a masters degree in chem to understand black-body radiation :("
] | [
"naw, you'll need one in physics :P"
] |
[
"Why are there no stars in pictures of earth taken from space?"
] | [
false
] | I was having a debate about the validity of the space program with one of my coworkers. He is a moon landing denier and asked me this question to which I was stumped. | [
"Just to clarify, it has nothing to do with \"focus\" necessarily, and everything to do with exposure.",
"Quite simply, both film and digital cameras have a very limited range of exposure. You can expose for the deepest shadows by letting a lot of light through the lens, but then you end up with blown-out highlig... | [
"It's because cameras have to focus on a light source. The amount of light earth reflects back into the camera is so intense, focusing it causes the much dimmer stars I'm the distance to disappear. \nIf they held up a piece of paper and blocked the earth from view when they snapped the picture, the stars would come... | [
"The premise is false. There are photos of earth from space with stars. Its just a matter of finding the right photo that has the right exposure.\nFor example here: A long exposure taken with a UV camera.",
"http://en.wikipedia.org/wiki/File:Apollo16EarthID.gif",
"The same reason you cant see stars during the d... |
[
"How do astronomers pick up signals from the early universe?"
] | [
false
] | I understand they travel at the speed of light and are from far away, hence they are from billions of years ago , but if matter expands at less of the speed of light then shouldn't those signals have gone past us long ago ? | [
"matter expands at less than the speed of light",
"That's where you're confused. Matter doesn't expand. Space does, and matter is pretty much fixed in space (at super ginormous scales where galaxy clusters form filaments). Whatever the actual rate of expansion is, as long as it expands at all, then there is a rad... | [
"Thanks!"
] | [
"Also OP needs to know that in the case of the ",
"cosmic microwave background",
", the EM radiation IS traveling at the SOL. But even that presents a problem. How did the CMB become so perfectly uniform? There was not enough time for thermal equilibrium to have happened. So theories on how this happened have b... |
[
"Does electrical current have something similar to a water hammer?"
] | [
false
] | I understand that electrical current is the flow of electrons through a conductor. It is often compared the water flowing through a pipe. When water is rapidly shut off it can cause a water hammer. Does something similar happen when electrical current is rapidly stopped? | [
"Yes. If there is inductance in the circuit which is sort of like momentum then when you have a sudden change in current (closing a switch) you get a spike in voltage. Given we manage lots of power these days by turning transistors (elctonic switches) on and off very fast this is an important phenomenon. The soluti... | [
"While it is a good analogy it does lead to some really bad ideas. ",
"Things that directly lead to a large water hammer, like a long straight pipe, have nearly no impact in a circuit. Nearly none of the steps I would use to reduce water hammer would have an application in circuits. Things that increase the im... | [
"This effect can be also used in boost converters for generating a higher voltage from a lower one."
] |
[
"Why doesn't a star's gravity disturb its planets' moons?"
] | [
false
] | null | [
"There's the concept of the ",
"sphere of influence",
" where the gravity of a planet, despite being weaker than the star, is locally dominant due to the short distance. Therefore a moon or an artificial satellite can still be in orbit around a planet despite the presence of a much larger attractor.",
"The st... | [
"The star is still attracting the moon and the moon is still orbiting the star. But the planet-moon system is still attracted as a whole, so in a reference frame centered on the planet you can still see the moon orbiting the planet.",
"I think this is the most important point if you want an intuitive grasp of it.... | [
"If you place an artificial satellite at this distance it will be too unstable to orbit the Earth.",
"You mean no artificial satellities can have stable orbit at same altitude as where the moon is? Is this because of the moon, or because of the sun? ",
"Or did you mean at twise the moons altitude?",
"And what... |
[
"Why is it that in some areas, the western side of a mountain range is desert and the eastern side is lush, but in other (sometimes nearby) regions, the opposite is true?"
] | [
false
] | I noticed this looking at the satellite view of , where there appears to be a flip to the north of Santiago. What accounts for this? | [
"For the Andes, in addition to the orographic effects described in the other answers, because the mountain range spans such a huge range of latitudes, you are also seeing some influence of global scale atmospheric effects, like the ",
"Hadley Cell",
". There's a nice discussion of the interaction of local and g... | [
"The Rain Shadow effect is well covered here, but the \"flip\" of the Andes is also due largely to the Hadley Cell effect, in which latitude determines general wind direction. ",
"This image",
" shows the South American situation nicely- the wind coming directly from the ocean is wet, and that same wind becomes... | [
"The cells themselves are due to the coriolis effect, which has more to do with the fundamental physics of our orbit and planet shape than temperature or chemical makeup of the atmosphere. So, the fundamental driver of the wind cells won't change.",
"That's not to say that there can't be local effects from climat... |
[
"Will water cool faster, slower, or at the same rate at higher vs. lower temperatures?"
] | [
false
] | If I put a glass of water, that is at 60°, in a room that is 65°, would the water get to room temperature faster than a glass of water at 35°, in a room that is at 40°? | [
"Okay, so the traditional thermodynamics answer is that the cold one gets to room temperature first. It takes a certain amount of energy to cool the water per unit temperature and the atmosphere can only supply that energy at an (approximately) constant rate.",
"Now if you put the glasses in a freezer, counter-in... | [
"Semantics.",
"The definition of cool is 'A fairly low temperature.'. If the temperature drops then it is, by definition, 'a fairly low temperature' relative to it's previous temperature.",
"It's not a scientific term, but there's not reason to be so nit picky. There are plenty of questions that don't use scien... | [
"It all depends on the accuracy that you desire in your answer. To a first approximation, they both will reach their new temperature at the same time.",
"But if you dig in enough and get picky enough, you will start to find some differences. The heat capacity of water will show small changes with temperature, as ... |
[
"Why doesn't water ever get 'red hot' or emit light when heated or vaporized?"
] | [
false
] | Even glass does this. | [
"The underlying principle here is blackbody radiation. The simple answer is that water never gets hot enough to emit blackbody radiation before vaporizing, at which point it is dispersed into the air and cools very rapidly. ",
"Wien's law",
" tells us how hot a blackbody (or to decent approximation, any commo... | [
"Glass, iron etc glow when heated because the atoms in the structure vibrate rapidly without actually leaving the structure. It's called incandescence. Solid/liquid water doesn't do this (at 1 atm) because it becomes a gas before reaching incandescent temperatures. Well, it does emit, but not in the visible spectru... | [
"Considering there are ways to increase the boiling temperature considerably, could it be possible then? What about visible light?"
] |
[
"If hot water cleans more effectively, then why do we brush our teeth with cold water?"
] | [
false
] | null | [
"Put a toothbrush in your mouth for 5 seconds and it will heat up (or cool down) to the temperature of the inside of your mouth. It wouldn't matter if you wet the brush with cold or hot water, you're brushing at body temperature in the end."
] | [
"Many people thinks its the detergent in the toothpaste that does the cleaning but this isn't the case. Many companies add sodium lauryl sulfate to the tooth paste to the provide the foam that everyone associates with cleanliness, using a toothpaste that does not foam just isn't satisfying. It's actually the abbr... | [
"This was why i didnt use warm water, my grandmother always used to tell me it would poison me haha\nAll i know is that everyone i've asked outside brushes their teeth with cold water."
] |
[
"Does taking medication for cold symptoms delay your body's ability to fight the illness?"
] | [
false
] | null | [
"Here's an evidence-based answer from a review done in January of 2004 from the Journal of Family Practice.",
"Generally, the use of acetaminophen/paracetamol (brand name Tylenol) did not affect the course of of rhinovirus (common cold), varicella (chicken pox), and may even prolong the course of shigellosis (bac... | [
"Cold medications consist (usually) of many different ingredients such as diphenhydramine for sneezing/runny nose, acetaminophen for pain/fever, a decongestant such as pseudoephedrine or phenylephrine, and sometimes and anti-cough or expectorant. ",
"The important thing to remember is that all of these medication... | [
"Hi Clessa, great response. ",
"The one issue I have with this response is that \"prolongs the course of illness\" is rather imprecise. Are we talking hours, days or weeks? What's the margin of error?",
"Edit: I'm clearly blind."
] |
[
"Say that I weigh myself just before bed: 150lbs. I weigh myself immediately after waking: 148lbs. What processes happen while I sleep that cause this overall loss of mass overnight?"
] | [
false
] | [deleted] | [
"The weight loss would be due to breathing, mainly in the form of expelled carbon dioxide with some water vapor as well. You intake oxygen, but expel carbon dioxide (basically just an oxygen molecule plus a carbon atom), with that extra carbon coming from the food you ate. All the carbon adds up. You also lose s... | [
"There are some nice answers in this thread involving respiration. First you should calibrate your scale at those two times of the day; it is likely that the temperature is different in the morning and evening, and if you're using an inexpensive scale temperature may be important. You can do this by taking a heav... | [
"I'd also expect this to be a measurement error of some sort. There is no way you could exhale two pounds of carbon dioxide in a night, although you might exhale a detectable amount of mass as water vapor."
] |
[
"Is there a \"deeper,\" physical explanation for QM uncertainty or complementarity in particle-spin measurements?"
] | [
false
] | I gather that spin about orthogonal axes is subject to uncertainty in that (roughly speaking) if we know x-spin at 100% confidence, then we can only guess y-spin at 50%, and vice-versa. I also gather that the mathematical formalism requires this. But is there a known or hypothesized (physical) explanation for why spin ... | [
"The act of treating \"quantum uncertainty\" as a literal uncertainty is to treat a quantum particle as a literal particle. But that is not the current mainstream interpretation of quantum particles. Rather, a quantum particle such as an electron is a wave-like fluctuation in a quantum field. So, \"uncertainty\" is... | [
"Okay, this is pretty helpful; thanks again!"
] | [
"Any \"deeper\" physical understanding is entirely dependent on your interpretation, so there really is no one clear cut answer, sorry."
] |
[
"Lottery lightning strikes twice?"
] | [
false
] | Hypothetical: I buy a lottery ticket from a convenience store in California and win the jackpot. The chances were 20 million to one -- 20 million tickets sold in the state of California. The next week I buy another lottery ticket from the same location. The chances of winning are the same -- 20 million to one. I argue ... | [
"You're absolutely right - the chances of you winning the lottery the second week are the same as they were the first week (1 in 176 million).",
"Where the odds get longer is if you ask the question 'what are the chances of someone winning the lottery two weeks in a row'. In that case you multiply the probabilit... | [
"\"The lottery is not lightning. Your chances of winning are not affected by the results of previous lotteries.\"",
"Of course, lightning isn't affected by the results of previous lightning strikes either."
] | [
"except lightning isn't random. if lightning hits somewhere twice for example, there's a good chance theres a reason and it's more likely to hit there again. if lightning never hit twice, there would be no use for lightning rods on tall buildings. i don't know the physics behind lightning, but on flat ground it may... |
[
"Is there a stable solution of n-body orbits in 3D where one body is significantly smaller than the rest?"
] | [
false
] | This question was brought on by the recent question about 6 blackholes arranged in a cube, which had some obvious problems, but it got me thinking about wether you could have a stable multibody orbit like a stable Plummer sphere as shown here: with all the bodies bar 1 being blackholes, and the final body being a human... | [
"If you meant in 3D, as in, non-trival solutions, I don't have a response. However, there is a stable but trivial n-body system of the masses arranged in any collinear orientation, and with rotation around the center of mass."
] | [
"No? I said no such thing. I said I have no response for general systems, as I'm not an expert. I only have enough knowledge to suggest that there is a specific construction of n-bodies (for all n) that is stable (in relation to each other).",
"I don't know enough about orbital systems and the math behind them to... | [
"You might want to read about lagrange points, where objects can hold their relative position in relation to two other more massive objects. Of the 5 lagrange points in a 2 body system, 2 are stable.",
"https://en.m.wikipedia.org/wiki/Lagrangian_point",
"In addition to the lagrange points made by the sun earth ... |
[
"Can light polarization be explained as an emergent property of a photon? (quantum mechanically)"
] | [
false
] | I'm familiar with the classical description of light polarization ) and I'm familiar with basic quantum mechanics... but how does polarization emerge from a photon's properties? Does a photon have an orientation? If so, how? | [
"Polarization is an intrinsic property of photons. Polarization with which you're familiar actually arises from the spin of the photons.",
"Because photons are massless and spin 1 particles, we can describe any state by breaking it down into states that have spin 1 aligned along the direction of motion or spin 1... | [
"Great answer, thanks!",
"Polarization is an intrinsic property of photons. Polarization with which you're familiar actually arises from the spin of the photons.",
"I was wondering if that was the case, since spin is the only property I know of with some \"direction\" to it.",
"Because photons are massless an... | [
"To my knowledge it A good rule of thumb is that ",
". This means that any interaction with matter - absorption and emission - must occur in discrete chunks of ",
" which we chose to name \"photons\". Another way to think of this is that \"photon\" is the name we give to a unit of ",
", not the EM field.",
... |
[
"After the COVID vaccine is out will we still need to social distance and wear masks?"
] | [
false
] | Oxford said that by the end of 2020 there will be millions of doses of the vaccine available to the public. With all of those doses out and millions more coming in the following months, when will all of the restrictions be lifted and we can return to normal life? Edit: Wow, I was not expecting this to blow up like it d... | [
"Yes. It will take a long time for the vaccine to deploy, especially to countries that have poorer economies and inadequate healthcare systems. In addition, if travel is less restricted, community transmission will continue to be a risk. Nobody really knows when the right time to open up will be."
] | [
"First thing to note is that while we have phase 1 and 2 data for several of the early vaccine candidates we have no phase 3 data, which is where vaccines shows how effective they are. Some of the ones we hope will work may not prove to work or they could show bad adverse events in a larger population. Phase 1 and ... | [
"It helps to understand the scale involved. If vaccine development successfully finishes on October 1 and they can make a million doses a day (which may be optimistic, but they’re trying to get a jump on production before trials finish), then there will be 92 million doses manufactured by New Years. If every sing... |
[
"Why don't moths fly toward the sun?"
] | [
false
] | [deleted] | [
"Insects often use the sun for navigation purposes. Imagine that it's daytime, and you want to travel in a straight line. As long as you're not traveling for hours and hours, you can get a pretty good approximation of a straight line by keeping the sun in the same position in the sky (say, to your left). Since t... | [
"I managed to find some quotes from a book called ",
"Ecological Consequences of Artificial Night Lighting",
":",
"Several theories try to explain the behavior of moths around artificial sources of light, but none accounts for the diversity of observed behaviors. The light-compass theory postulates that moth... | [
"I managed to find some quotes from a book called ",
"Ecological Consequences of Artificial Night Lighting",
":",
"Several theories try to explain the behavior of moths around artificial sources of light, but none accounts for the diversity of observed behaviors. The light-compass theory postulates that moth... |
[
"Can forces act across time as well as across space?"
] | [
false
] | If time is just another dimension of space (equivalent to l, w, h), then do gravity and electromagnetism (and the other two forces) act on objects in the past and/or future? | [
"If time is just another dimension of space (equivalent to l, w, h)",
"Time is different from space. In general (or even special) relativity, time is considered one dimension of space-time (hence the name), because you can't study space and time separately.",
"Electromagnetism and (AFAIK) gravitation propagate ... | [
"The universe is not isotropic in the time direction. You might be interested in ",
"maximally symmetric spacetimes",
", one example of which I've linked. ",
"I guess, broadly, the pattern over time seems to have been that energy density has been decreasing, while always being homogeneously and isotropically ... | [
"Related question:",
"We know that matter/energy in the universe have homogenous distribution on the large scales.",
"Can we name any pattern regarding the distribution of events over the history of the universe?"
] |
[
"Why do people have different blood types?"
] | [
false
] | [deleted] | [
"Same reason we have different eye colours and different hair colours. Arbitrary differences mean that there were random mutations somewhere along the line.",
"Also, the differences may be arbitrary, but what if a disease came along that only killed people with, say, B type blood? Or a disease that only A types c... | [
"Use the search function, question has been asked twice:",
"http://www.reddit.com/r/askscience/comments/f19p4/how_or_why_did_blood_types_evolve_is_there_any/",
"http://www.reddit.com/r/askscience/comments/iepiv/why_did_we_evolve_with_different_blood_types/"
] | [
"Its cool that you don't want to see repetition too often but what I don't like is the discouraging of discussion. Just because a question has been answered does not mean there isn't more to talk about. ",
"The idea of \"Just use the search function\" is the same as saying \"Just Google it\", pretty much making "... |
[
"How does my body form antibodies against the antigens of other blood types eventhough i have never been exposed to them? ( for eg how did a person with O blood group form anti-a and anti-b?)"
] | [
false
] | null | [
"Contrary to how it may be presented in general discussions, your body does not \"form\" antibodies in response to antigens. Rather, when antibody producing cells differentiate (become antibody producing cells from more general precursor cells) the portion of the genome that is responsible for producing the antibod... | [
"Blood Bank Guy is a pretty well known resource for students on the subject, and he has a good ",
"primer on ABO",
" testing. The straight forward, low-level answer:",
"When humans are born, we have no ABO antibodies of our own (we may have a few floating around from our mom, but we haven’t made any yet). As ... | [
"I just took an immunohematology course and this is the way we learned it. The bacteria in our environment are responsible for a person acquiring anti-a and anti-b seemingly without any exposure."
] |
[
"If aliens were to look at earth through a telescope from 65 million lightyears away, would they see dinosaurs?"
] | [
false
] | [deleted] | [
"So I should add like two more ",
"'s?"
] | [
"Yes.*",
"*But this telescope would have to be very, very, very large to have the proper resolution to see Earth, let alone individual objects on Earth."
] | [
"very, very, very large ",
"Read: impossibly large. To resolve the earth as a single pixel at a distance of 65 million light years a lens would be large enough to fill most of the inside of Mercury's orbit. "
] |
[
"What is the hottest object in the known universe?"
] | [
false
] | I know this is a stupid question, but I am interested in knowing | [
"It's actually the quark-gluon plasmas produced in the Large Hadron Collider and and Relativistic Heavy Ion Collider. They can reach trillions of degrees."
] | [
"It's within a very small volume...like the size of atomic nucleus."
] | [
"Not only is this intense heat in a very small volume, but it is also only that hot for an extremely short amount of time"
] |
[
"Why don't we snore while awake? What changes in our breathing when we fall asleep?"
] | [
false
] | null | [
"Respiratory therapy student checking in. There are a few factors which may compound with eachother causing symptoms ranging from simple snoring, to severe sleep apnea. As mentioned earlier, the snoring sound comes from a closing airway in the back of your mouth/throat. ",
"While we sleep we have different stag... | [
"Some people do snore while awake! This is called stertor. It is usually associated with airway narrowing or loss of muscular tone. \nThe true question then becomes: Why do people snore more often when asleep? This is because our muscular tone is lower while sleeping. \nIn short, snoring/stertor comes from vibr... | [
"I'm a sleep tech. People that come in snoring while they're awake....its like a neon sign that says severe sleep apnea. "
] |
[
"Can an airplane traveling along magnetic field lines become magnetized?"
] | [
false
] | This stems from my knowledge that in order to magnetize something like a screwdriver, you physically move the object through a magnetic field ALONG the magnetic field lines. The earth has a natural magnetic field running basically longitudinally. If an airplane were to leave from the magnetic south pole due directly ma... | [
"So, as has been stated, Aluminum is not ",
"ferromagnetic",
", and cannot be magnetized even if you tried.",
"Basically, magnetization occurs when the atoms making up the material have a dipole moment because of a lone electron orbiting. When the dipole is subject to a magnetic field, it tends to align with ... | [
"Earths magnetic field is too weak to have any noticeable effect and aircraft are usually made of aluminum which cannot be magnetized."
] | [
"Maybe you were thinking of this already but steel ships can become magnetized. The Navy has a facility to degauss them ",
"http://en.wikipedia.org/wiki/Deperming"
] |
[
"Where can I find information/charts about efficiency of vaccines?"
] | [
false
] | I have tried to find a char with 3 variables for several illnesses, i am specially interested in infections where the vaccine is not very effective and with a long incubation period. I am trying to make an interactive page where you see an scenario for example a classroom or a zoo visit with an X% of kids who are not v... | [
"Truthfully I don't know of many places that would give all this information so succinctly to you. You would have to do a bit of research. Here is a link to the CDC list of curent vaccines available in the US ",
"http://www.cdc.gov/vaccines/vpd-vac/vaccines-list.htm",
". You can just google them 1 by 1 to get t... | [
"why wouldn't that be public information?"
] | [
"Efficacy rates of the vaccine and infection rates in vaccinated individuals are fairly complicated.",
"For example, the tuberculosis vaccine most commonly used (BCG) varies in efficacy in different regions. Part of this is that different regions have different strains of the vaccine (and different strains of tu... |
[
"Is it actually possible to suffer a heart attack from being scared or startled?"
] | [
false
] | I just read another Reddit post about a woman who was presumed dead, only to wake up at her funeral, then dying of a heart attack because she was so shocked at the fact that she woke up at her funeral. Is this actually possible? I assume that if you already have a weak heart it's likely, but what if you have a healthy ... | [
"As ",
"/u/eosha",
" said, if there is some underlying ",
"coronary artery disease",
", a sudden elevation of blood pressure or heart rate triggered by a ",
"sympathetic surge",
" could be enough to cause a plaque to rupture and cause ",
"infarction",
".",
"This is also a condition triggered by st... | [
"Yes. Fear can activate the body's sympathetic nervous system, which controls heart rate and blood pressure, among other things. In extreme cases, or if the circulatory system is already damaged/weak this can cause stroke, heart attack, etc.",
"http://www.scientificamerican.com/article.cfm?id=scared-to-death-hear... | [
"This is good info. Thank you."
] |
[
"Why are heavy duty wires not made of one solid wire?"
] | [
false
] | What's the reason for this? Is it to increase flexibility or strength? Or one Solid Wire is never invented in the first place? | [
"Higher strength, way better flexibility (thick wire is technically a rod).",
"\nAlso - the ",
"skin effect",
" which makes the AC electricity run on the outer shell of the wire, which makes more wires - more surface."
] | [
"the skin effect which makes the AC electricity run on the outer shell of the wire, which makes more wires - more surface.",
"If the strands of a stranded cable are not insulated, then there isn't much difference in skin effect between a solid wire and a stranded one. If you are concerned about skin effect, you e... | [
"Mostly flexibility and ease of handling. But also for strength; drawing a wire down in diameter (pulling it through a hole in a plate to make it thinner) aligns the metal crystals similar to how forging does. Depending on what equipment is used, there's a limit to how thick a wire you can practically draw throug... |
[
"How far would a bullet have to travel for it to be affected by the Coriolis effect?"
] | [
false
] | [deleted] | [
"Not a scientific answer, but when I was a scout in the army our sniper section guys told me they compensate for it on north/south shots over 1000 meters."
] | [
"Here's a very simplified and completely hypothetical/theoretical approach to determine whether or not Coriolis would affect it:",
"Imagine you shoot the bullet from the North Pole due South. You are aiming towards, say, China. If the bullet instantaneously got to its destination, you would hit China. If it took,... | [
"What is your threshold for defining something as being \"affected\"? Your answer depends entirely on that."
] |
[
"What is the maximum length of a peptide and minimum length of a protein?"
] | [
false
] | Also, linking to an article would be nice, I know what wikipedia says. | [
"Interesting question. A peptide is technically any two or more amino acids linked by a peptide bond, so there is no maximum size. All proteins are peptide chains, the largest one in humans is titin, a spring-like muscle protein comprised of 34350 amino acids. Its virtually impossible to work with biochemically as... | [
"it's an arbitrary distinction, which is what Wikipedia says. So why are you asking for a definition? For what it's worth, the ",
"IUPAC",
" says proteins have \"molecular weights greater than about 10000 (the limit is not precise).\"",
"It's like asking \"What's the maximum length of stubble and the minimum ... | [
"Actually, scratch that. I just remembered that there are so called Anti-Microbial Peptides - gene products involved in innate host response to pathogens. They are termed peptides despite being complete gene products I suppose because they are so small. But, again, there is no strict rule about it. You could call t... |
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