title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why did China's recent easing of it's COVID restrictions lead to such a huge explosion in new cases?"
] | [
false
] | null | [
"They had an active circulation of a highly contagious variant, in a very dense population in winter with essentially no transmission resistance when they did it.",
"The current Omicron variant is very distant from the initial strain that was the basis for the vaccines, and the Chinese vaccines to begin with had ... | [
"I can see this thread being locked...",
"Relying on lockdown rather than an immunisation strategy meant that when the restrictions were eased folk started mixing who had no immunity causing a spike in cases.",
"Also, there is a good chance that the numbers before the change in policy were probably optimistic, ... | [
"Compared to the mRNA vaccines, China’s vaccine (Sinevac) was less effective against the original strain and is almost ineffective against omicron. ",
"The strict isolation and lock-down policies prevented most of the population from getting covid, so there is very little natural immunity. Immunity also wanes ver... |
[
"What if there was a place with no Higgs-Boson particles?"
] | [
false
] | So my limited understanding of Higgs-Boson, it's theorized as being the particle that gives other particles mass, and that there's a "fog" of Higgs-Boson particles evenly distributed throughout the universe which is why the mass of an object is the same everywhere in the universe. Feel free to correct me if I'm wrong. Now if we assume that Higgs-Boson exists and it's properties are what we currently assume them to be; What would happen in a place with no Higgs-Boson particles? Or on the other hand what would happen if some place had a higher concentration of HB particles? Say could a human still survive there? Or what sort of implications would this have the relativity? | [
"You don't need Higgs bosons to have a Higgs field (what you call a \"fog\") any more than you need ripples in order to have a lake. The Higgs field permeates all of space, just like the electromagnetic field, the gravitational field, and so on. There wouldn't be a place where that field doesn't exist. The Higgs bo... | [
"Also the electroweak symmetry would be unbroken. Electromagnetism and the weak force would very obviously be different components of a single force. What this would look like, I'm not sure. At high enough energies (above the ",
") this is the case."
] | [
"The things we ",
" to detect."
] |
[
"Boiling water in plastic bottle"
] | [
true
] | [deleted] | [
"It's the ",
"glass transition",
", of PET probably. The change is just the plastic molecules having gained enough freedom of movement from the thermal energy to re-arrange themselves into a more comfortable shape. I doubt it would have any significant impact on the rate at which anything leaches into the liqui... | [
"Plastic bags, huh? Those would normally be polyethylene, which to my knowledge has never had BPA in it in the first place, or any other additives. Sounds like a marketing gimmick to me. Anyway, BPA is used as a plasticizer; an additive that makes hard plastics soft. Mainly polycarbonate and PVC from what I know, w... | [
"If you're boiling water in a plastic container, your life is already operating under sub-optimal conditions. For wilderness survival, the short-term exposure to chemical leeching is less dangerous than a bout of protozoal diarrhea. "
] |
[
"What happens to a computer in the gap between between basic theory and a programming language?"
] | [
false
] | There is a gap in most of the information I have looked up. They explain the theory really simply, referring to basic "On Off" switches. I understand that part. Then they explain basic programming code. Which I also understand the theory of. But what comes in between? How does a computer get from analyzing milions of zeroes and ones a second to recognizing and forming a command. How does a computer remember what it's supposed to do? What happens in the gap between the time data is read off of a memory chip and the time that the computer recognizes a piece of source code that it can use? | [
"But what comes in between? How does a computer get from analyzing milions of zeroes and ones a second to recognizing and forming a command. How does a computer remember what it's supposed to do?",
"Ultimately what it comes down to is, you have your programming \"source code\" which is human-readable, which then ... | [
"The gap you described can be broken down into several layers:",
"Programming Language (C, Python, etc)",
"Assembly Language",
"Machine Language",
"Microcode",
"Logic Gates and Flip-Flops (zeros and ones)",
"Transistors and Diodes",
"Electrons and Atoms",
"It may be easier to learn about these conce... | [
"I'll try and give a simplistic explanation. Note that I omit a lot of details, and exactly what happens depends on the language used, operating system, processor, etc.",
"First, you write source code in C/C++, or your favorite language. Next, when you compile it, the compiler translates \"source code\" into \"ob... |
[
"If I smell something, does that mean I'm taking the smell away?"
] | [
false
] | If were to smell a fresh baked loaf of bread, or someone's perfume, would that mean there would be less fragrance for someone else to smell? Would the scent become weaker until there was none left? | [
"To set off your sense of smell only takes a few thousand molecules of an odor or fragrance. A loaf of bread or someone's perfume are giving off literally trillions of individual molecules, and refreshing the output of those molecules every second. Your inhaling a few of those molecules is not going to deplete but ... | [
"This is the basis of a filtering system, to vastly expand the volume of air in question, if you had a fan pulling the room air through a carbon filter, the carbon will absorb the molecules in the air producing the odor, and reduce the overall amount in the room, much like your nose would, on a much smaller scale."... | [
"That is a psychological phenomenon, similar to how your brain can tune out repetitive or monotonous sounds."
] |
[
"Can Someone Please Explain, in Layman's Terms, How Electric Eels Work?"
] | [
false
] | I tried reading the Wikipedia article, and frankly, I think it's poorly written. It had a bunch of links to other articles, which in turn link to other articles, and onto others... yadda yadda yadda. And there's a bunch of technical jargon which leaves me like, "I'm not a scientist, so what the fuck do all these words mean?" So could someone please explain, in layman's terms, the following: How are electrical eels (and other electric fish) are able to generate electricity? (I saw something about "organs") Is it enough to kill a human? (I saw this YouTube video where an eel killed a baby alligator, and another lit up a Christmas tree in Japan) Could other animals be genetically modified to do this? | [
"This might be better suited to ",
"/r/explainlikeimfive",
" :)"
] | [
"I'm not among those who downvoted you, but I'll give it a try."
] | [
"All animal cells have sodium/potassium pumps in their cell membranes. Each time these pump, they move 3 positively charged sodium ions outside the cell, and 2 positively charged potassium ions in. This creates a negative charge inside the cell and a positive charge outside it, and the cell must spend energy to do ... |
[
"What would happen if our Sun was replaced by a 1 solar mass black hole?"
] | [
false
] | [deleted] | [
"It would get very dark and cold here."
] | [
"Aside from the loss of heat/light, nothing. We would still be in orbit around it and it would be incredibly tiny. I'm to lazy to compute the size, but you can use this equation if you're interested.",
"http://en.wikipedia.org/wiki/Schwarzschild_radius#Formula_for_the_Schwarzschild_radius"
] | [
"So the pressures and outward forces of the Sun, like the solar wind, wouldn't be missed? I was thinking that since the Sun pushes things outward and a black hole sucks things in that the planets would either have to compensate by orbiting faster or moving further away, or they would eventually get sucked in. But I... |
[
"Why can the sum of two cubes never be prime, but the sum of two squares can?"
] | [
false
] | 1 is the only number that gives you a prime from what I've found, because 1 + 1 = 2. Im pretty sure the sum of two numbers that are both to an odd power can never be prime, but im not sure. Is there a proof for this? | [
"Assuming positive integers",
"a",
" + b",
" = (a + b)(a",
" - ab + b",
" )",
"(a + b) will be a factor of the number, and for positive integers",
"2 <= (a + b) < (a",
" + b",
" )",
"Thus, whatever number you get will always at least have (a + b) as a factor that's not 1 or itself, with 2 as the... | [
"When n is odd, you can factor the sum explicitly: ",
"a",
"+b",
" = (a+b)sum{k=0,n-1}(-1)",
"a",
"b",
"E.G. a",
"+b",
" = (a+b)(a",
"-a",
"b+a",
"b",
"-a",
"b",
"+a",
"b",
"-ab",
"+b",
")",
"Note the alternating signs force the \"middle\" terms of the product to cancel.",
"... | [
"This shows why a sum of cubes cannot be prime. As for why a sum of squares ",
", you could just say that 5=1",
"+2",
" and be done, but this just says ",
" primes can be a sum of square, and not why. The reason why is because sums of squares have really nice divisibility properties. ",
"In particular, we... |
[
"has the speed of light always been constant?"
] | [
false
] | null | [
"In short, yes. ",
"In not short, there are some more fringe theories coming out of quantum mechanics that posit that the speed of light (or more specifically the speed of causality) has changed slightly over time. However I've never seen anything serious come out of such papers."
] | [
"Again, my understanding is fairly limited and largely from popular press like a brief history of time and such. So any errors here are all me.",
"In that case please refrain from commenting, especially on very technical topic such as this one. A good rule of thumb is that if you can't provide peer reviewed sourc... | [
"Again, my understanding is fairly limited and largely from popular press like a brief history of time and such. So any errors here are all me.",
"In that case please refrain from commenting, especially on very technical topic such as this one. A good rule of thumb is that if you can't provide peer reviewed sourc... |
[
"Why do some quantities in physics calculations (electricity for example) take on complex values?"
] | [
false
] | College student here. I stumbled upon equations in physics on my own that take complex valued quantities. My question is: how can something like electrical impedance or current take on a complex value? | [
"It is a mathematical trick -- and a very good and useful one -- to use complex numbers in the situation you describe, AC circuit analysis.",
"The physical current is real, no question about it. But if we embed that current in a complex expression, such that the real current is the real part of that complex expr... | [
"A lot of things that are formulated in terms of complex numbers can actually be reformulated as two sets of coupled equations. In such case the use of complex numbers is just convenient. The reason it is convenient is that calculus of the complex numbers can actually be a lot more powerful than calculus of the r... | [
"Because integrals in the complex plane are generally zero or take some nice form where you can do things like the Residue theorem. In general contour integration gives your more freedom to deal with messy math. In essence, in the complex plane you have a certain amount of freedom in how an integral is performed ... |
[
"What did I just see? (Biology related)"
] | [
false
] | [deleted] | [
"I'm not an expert on birds, but I've seen this behavior before and wondered about it. ",
"As a result, I searched around a bit and found it's called the \"spread wing posture\" and is commonly used to thermoregulate (either cool off by pressing the breast into the ground or expose area to sunlight to warm up, de... | [
"Please do not reply as if you give an answer if you don't know the answer. Speculation is not an answer."
] | [
"Please do not reply as if you give an answer if you don't know the answer. Speculation is not an answer."
] |
[
"What is going on at the atomic level when my skin touches another object? How come we don't fuse with the things we touch?"
] | [
false
] | null | [
"When you say why don't we \"fuse\" with the objects we touch, what I would say you are describing can be re-stated as; why don't the molecules that make up our skin form bonds with the molecules that make up the object we are touching? ",
"For the case of your skin touching something that isn't skin - Your skin ... | [
"Q1: you dont actually ever \"touch\" another object, as in the distance between your skin and the object is 0. the electrons (negative charge) and nuclei (positive charge) of your skin and the object repel each other so strongly that they prevent the distance of closest of approach from reaching zero. afaik this i... | [
"In theory, I could see this being possible. Wounds send signals for your cells to migrate to and proliferate at the wound site. Whether or not this would cause the cells of two different people to fuse I am not sure. I do not suspect it would be very successful though, as having another persons skin cells form int... |
[
"If darker colors absorb more heat, why is our skin made to darken when exposed to the sun?"
] | [
false
] | null | [
"Because the problem with sunlight is not the heat, but the exposure to UV radiation, which damages skin cells and their DNA, leading to sunburn in the short term, and to melanoma and other problems in the long term. \nMelanin, the pigment responsible for the darkening of the skin, is placed above the DNA of skin c... | [
"It's complicated. Short answer: not really, as the fact that melanin is dark is probably a byproduct of its qualities and of the necessities of the body, although it does absorb the light that would damage the DNA. It might seem strange, but the long answer explains why.",
"Long answer - it requires a bit of bac... | [
"Skin pigmentation isn't about dealing with heat, it's about avoiding the harmful effects of ultraviolet radiation from the sun. Melanin is good at absorbing UV, and thus preventing it from penetrating to deeper skin layers and causing second-degree burns and cancer. In places where it isn't really bright all the t... |
[
"Why does stainless steel have a higher density than carbon steel?"
] | [
false
] | [deleted] | [
"I'm going to wager that the chromium fits into the spaces between the iron atoms. So you're left with a crystal structure of slightly greater volume, and substantially more atoms. Hope that makes sense."
] | [
"When you alloy two materials, the alloy's density will not normally just be an average of the alloying materials. This is because the alloy's crystal structure (here it is crystal structure for the metals) is altered by containing the two materials.",
"To give a simple example: \nImagine a large box filled with... | [
"Plain iron, the dominate metal in steels, usually exists as a body centered cubic crystal arrangment (it can also exist as a face centered cubic). When the iron is alloyed with other metals (and carbon), the inclusions are typically found along interstitial sites in the crystal structure. As a result, more atoms... |
[
"Could a powerful enough magnet pull apart the Earth?"
] | [
false
] | I'm writing a Sci-Fi, and I'm wondering if its plausible or possible that if something gigantic and magnetic could pull apart the Earth. | [
"Since the earth is a magnet itself, if you have a very powerful (and I mean insanely powerful) magnet you might be able to twist the earth axis. Any magnet will align itself to the local magnetic field, but as far as I can imagine, no magnet will be torn apart. So that part is not possible.\nBut tilting the earth ... | [
"If you're writing sci-fi about very strong magnets, then you may be interested in ",
"this",
"."
] | [
"How to Destroy the Earth"
] |
[
"By what mechanism is silver (and other heavy metals supposedly) antimicrobial?"
] | [
false
] | Bonus Question: If silver is in fact antimicrobial and can kill off infections like MRSA and VRE can/will those organisms eventually develop a resistance to it as they have antibiotics? | [
"It is called oligodynamic effect (",
"wiki",
") and the exact mechanism is not completely understood AFAIK, but these metals are wide ranged catalysts, meaning they could easily push an otherwise stable protein over the treshold of some reaction that would denature it. This is most likely the effect. "
] | [
"A catalyst is a substance, a presence of which will lower the activation energy of a chemical reaction. In example, hydrogen and oxygen will not condense to water unless heated/ignited to a high temperature. If platinum is present, however, the reaction will take place at almost room temperature (very usefull to p... | [
"heavy metals interrupt disulfide bridges in proteins. This causes deformation in 3D shape and ultimately ceases function of proteins"
] |
[
"How are anti-quarks created?"
] | [
false
] | Using an anti-proton in this situation I assume that an anti-proton is made up from anti-quarks to give us the negative charge. However, I can't find a direct answer as to how those anti-quarks come about. The only thing I have found so far is that when you separate two quarks from one another (assuming they're paired some how) the energy required to do this creates two more, one quark and one anti-quark. Is this sort of correct or am I on the wrong path? Thanks | [
"Ah ok, cheers :) That was easy."
] | [
"Ah ok, cheers :) That was easy."
] | [
"Due to anti-matter being difficult to contain?"
] |
[
"Can I \"distill\" my fermented alcohol by adding molecular sieves?"
] | [
false
] | null | [
"You can certainly use 3a molecular sieves to dehydrate alcohol for consumption, as long as they are food grade. It's not used in large consumer alcohol operations because it would be so expensive. That's not the only reason you distill alcohols, though. There are plenty of higher-molecular weight fermentation b... | [
"Well, I suppose I chose the wrong word, concentrate would probably be more along the lines of what I was thinking, therein the higher weight stuff I don't necessarily mind, as I want to keep as much of everything else as possible but just remove the aqueous part to make it higher proof. My thoughts were that the ... | [
"im pretty sure any form of distilling is illegal without the proper permits. by the way, you can just use ice to freeze the water and remove it by hand."
] |
[
"What is the series for the number of faces if you have a cube with a slightly smaller cube attached to each face, and a small cube attached to each one of those faces, etc.. to infinity?"
] | [
false
] | I start out with a cube. That's 6 sides. If I put cubes on those 6 sides, then only 5 faces of each of those cubes would be showing because the attachment point is a hidden side. If I kept repeating this trend, what does the series look like for the number of faces? I feel like this is a simple math problem but I just can't figure it out. | [
"Let's write a[n] for the number of sides of this solid after n iterations, so a[1] = 6, a[2] = 36, etc.",
"We can write down a recurrence relation",
"a[n] = 6(1 + 5/6 a[n-1]) .",
"This is because on each of the 6 sides of the cube we're putting a smaller copy of the previous iteration with only 5 out of the ... | [
"The first few terms of the series are:",
"6 + 30 + 150 + 750 + ...",
"r > 1, so the series diverges to infinity. If we were looking at the surface area, then you might get a convergent series if the extra cubes are small enough."
] | [
"Your question doesn't agree with your subject line. If you're attaching \"slightly smaller\" cubes, then you won't be hiding the face they attach to- in that case, do you want to define \"face\" as being \"face of the new polyhedron\" or visible cube-faces\"?",
"Secondly, a series may not be the easiest way to t... |
[
"Why does the light from the moon not scatter and become blue upon entering Earth's atmosphere."
] | [
false
] | null | [
"A Full Moon is about half a million times dimmer than the Sun. As a result, the \"blue sky\" caused by the full Moon is similarly half a million times dimmer than the \"blue sky\" caused by the Sun.",
"The effect is still somewhat noticeable to the unaided eye, though. If you're in a place with dark skies when t... | [
"It does.",
"When it's low to the horizon, it's yellow - just like the sun. When it's high in the sky, the moon's light is distinctly blue. (Tough the moon itself is not - just as the sun is not.)"
] | [
"It is it's just very dim. Take ",
"this image",
" for example. It's a long exposure during a full moon. Since the shutter on the camera was open for several seconds (possibly a couple minutes), it was able to collect more light that the moon was giving off. In a camera this makes the image appear brighter and,... |
[
"What are the causes of friction at the atomic level?"
] | [
false
] | Since atoms never actually come into contact, but are repelled by their electrons, it would seem like there shouldn't be any friction at all. It seems like contact should behave like a maglev train system. This obviously isn't the case, so what's going on? | [
"What's going on is that the molecular maglev train is constantly running into bumps on the road.",
"If you take two surfaces in contact with each other, generally you're not talking about two atomically flat surfaces. As you can see from for example ",
"this",
" image of a razor blade, most materials more cl... | [
"The negatively-charged electrons do repel each other. However, the electromagnetic force scales weakly with distance (relative to some other fundamental forces), which means that even far away from each other, two electric charges will still interact with each other.",
"Put most simply, the electrons in one mole... | [
"So really the question is, how does an inelastic process come about in a material? How does kinetic energy dissipate?",
"I think what happens during a frictional process is you excite electrons when the materials are brought close together. For this to be a reversible process, the electrons would have to stay ... |
[
"Why does superconductivity occur in certain materials at low temperatures?"
] | [
false
] | null | [
"The key behind superconductivity is an attractive interaction between electrons, leading to bound states called Cooper pairs. In fact, if you have a metal and introduce a net attractive interaction between the electrons, a transition to superconductivity is inevitable. For \"conventional\" superconductors, you can... | [
"To add to this in light of OP's question, the strength of the effective attractive interaction between the electrons is quantified by an energy scale, let's call it ",
" This can be converted to a temperature by dividing by the Boltzmann constant:",
"_B = 1.3806488(13)×10",
" J⋅K−1",
"to give the appro... | [
"I have a question since it is sort of relevent. Has there been an example of super conductivity with + ions?"
] |
[
"Are there any pets which age at the same rate as humans?"
] | [
false
] | Basically is there a pet that would age at the same rate as their human owner, I know most smaller animals age at a much faster rate and one of our 'years' can equal several of theirs. | [
"African Gray Parrots",
" have an average lifespan of 50 years and a maximum known lifespan of 60 years. Not quite the same rate as a person, but longer than the scant ten to twenty year lifespan of dogs and cats."
] | [
"I have a parrot that was born in the same year as I. ",
"They",
" live 80 years."
] | [
"Fascinating, thanks very much. "
] |
[
"Would handling Martian soil be harmful to humans if we were to ever come into contact with it?"
] | [
false
] | I was reading that Martian soil was found to contain perchlorates and other chemistry which is not to friendly to organic matter. If we ever did send humans to Mars would the soil and rocks be considered hazardous to handle with bare hands? | [
"Not really. ",
"Almost entirely normal, everyday rocks",
" just like on Earth, just with a lot more iron oxide. Harmful chemicals are found in ",
" small quantities. Although the abundance of atmospheric dust may be harmful to human lungs."
] | [
"Dust gets everywhere. If you go outside, it will coat your spacesuit, and get into the air when you re-enter. This is an especially serious challenge for future long-term lunar colonies, as the complete lack of atmosphere there means the dust is unweathered and sharp, and could potentially cause ",
"serious lung... | [
"Dust gets everywhere. If you go outside, it will coat your spacesuit, and get into the air when you re-enter. This is an especially serious challenge for future long-term lunar colonies, as the complete lack of atmosphere there means the dust is unweathered and sharp, and could potentially cause ",
"serious lung... |
[
"Is the principle behind radiowaves inside coaxial cables and visible light inside optical cables the same?"
] | [
false
] | Is the principle behind radiowaves inside coaxial cables and visible light inside optical cables the same? The glass in optical cables is transparent for light in and arroud the visible spectrum. Is coaxial cables of aluminium and copper "transparent" for electromagnetic waves in the 30-1000Mhz range in the same sense? Also does the shielding on coax cables reflect and contain the radiowaves in the same sense as different types of glass keeps light contained in optical cables? I know this probably isnt exactly the same principle since the wavelengths are orders of magnutide different, but how close? | [
"The fundamental equations dictating how electromagnetic waves behave (Maxwell's equations/QED) are the same in both cases, since radio waves and light waves are both electromagnetic waves. But the exact mechanisms at work are different because they materials are engineered differently on purpose.",
"An EM wavegu... | [
"Coaxial fiber exists",
", the core isn't metal though. It's usually a cylinder of a different type of material or a hollow cylinder. These types of fiber are designed for things like maintaining polarization."
] | [
"What you linked to are photonic crystal optical fibers, which are not conductive coaxial cables at all. Photonic crystal fibers are just like regular optical fibers except you use the photonic crystal effect to get reflection at the edges of the core region instead of the effect of total internal reflection. "
] |
[
"Would a \"still suit\" from Dune actually work?"
] | [
false
] | null | [
"The suit would indeed kill you through heatstroke very quickly. The book tries to explain it away by saying the first layer is porous, allowing sweat to evaporate off of the skin. And then the secondary layers of the suit recapture that evaporated sweat. But this is completely ignoring the first law of thermodynam... | [
"I haven't read Dune in about 15 years but I remember them talking about how the suit is powered by pumps that you work just by walking. One of the characters even says that the boots can't be too tight because then the pumps won't work at full efficiency. Could it be possible to use this energy to convert the wate... | [
"I always imagined the surface layer of a still suit works like high efficiency heat exchanger, meaning the surface would be quite hot, hotter than the desert air, comparative to the layer touching the skin. Meaning you don't actually sweat that much in a still suit, its practically AC'd.",
"We would be incapable... |
[
"What does it actually mean to “burn fat” during exercise?"
] | [
false
] | I understand that the body can use carbs and/or fat as an energy source during exercise, in differing proportions depending on intensity, but what does “burning fat” during exercise actually mean, and how is it different to actually losing fat? If you do a long, low intensity workout where your body predominantly uses fat as its fuel source, will your body fat percentage be lower when you’re done? Is your body burning fat for fuel the same thing as when it loses fat due to a calorie deficit? | [
"The short answer to all your questions is, yes. Adipocytes (fat cells) store energy in large lipid droplets that are encased in their own single-layer phospholipid membrane. People tend to describe lypolysis (the breakdown of of fat) as though it doesn't happen until your body has completely exhausted all blood su... | [
"One thing I find really cool about weight loss is how the mass actually leaves the body. I don't remember the exact process, but ultimately it is mostly excreted via your lungs - all that carbon and oxygen is breathed out as carbon dioxide.",
"If my memory serves me correctly, when you want to know how many calo... | [
"I think the reason people talk about the body using up all its carbs before starting to munch on fat reserves is that sugar is the \"fast\" energy source. It is the easiest energy source for the body to use, because:\n- it requires little to no processing/metabolism/breaking down before its chemical energy can be... |
[
"I am drinking a glass of water and my lips keep getting shocked when I take a sip. What's going on here?"
] | [
false
] | I am drinking from a plastic cup and got the water out of a cooler at a coffee shop. When i use a straw I don't get shocked, but almost every time I sip straight from the cup I get what feels to be an electric shock on my lips. Why this is? | [
"The straw is an electrical insulator. Unplug the glass."
] | [
"Try it with your finger instead of your lips. Same result?"
] | [
"I don't have the cup anymore to try this with but judging by the way it was behaving I believe that it would have the same reaction as it did with my lips."
] |
[
"I have a question about the Twin Paradox."
] | [
false
] | null | [
"My question is, it possible for the space traveler to control his flight in a way, be it speed, flight time or distance traveled, to return to Earth at a predetermined future time.",
"What?",
"The space traveller can ",
" return to Earth at some future time.",
"And yes, by adjusting speed, flight time or ... | [
"This is wrong, the time difference occurs due to being at high speed and relativity, nothing to do with inertial reference."
] | [
"Presumably, yes. Knowing that the time dilation (to use science fiction terminology) would be proportional and thus calculable from the speed of travel (and time spent traveling at that speed), yes, one could plan a trip that would return them to Earth at a specific time."
] |
[
"Did the worms that used to bore into the hulls of ships face a decline in population as humans transitioned to using materials other than wood to build their vessels?"
] | [
false
] | Reading by Colin Woodard. Woodard frequently mentions that, in the Age of Sail, ships would have to frequently be careened so that their crews could clear the hull of barnacles and other sea life that damaged the hull. One such organism is a worm that would bore holes into the wood of the hull and cause the ship's structural integrity to weaken. Since humans have transitioned to using metal and fiberglass to construct ships and boats, have these worms declined in population? Or would these same worms also act as parasites to other marine organisms? | [
"The amount of wood in ships at any time in history would be dwarfed my the amount of wood that has fallen into the ocean due to storms and gradual erosion of riverbanks and coastlines. The worms did fine before wooden ships and fine afterwards"
] | [
"I don’t know how one defines “sizable” but as a reference point here’s a photo from Rialto Beach in Washington a few months ago. Each of those logs is an enormous tree. We saw logs that were 10-15’ in diameter and hundreds of feet long (big Douglas firs) and this driftwood covered multiple miles of beach up there ... | [
" or shipworm, is essentially ",
"today at it's highest population in history",
". It is an invasive species that displaces native wood-eating species.",
"There were a few population spikes in the 1930's, 1950's, but the entire range has spread since then. For instance, it was first detected in Oregon in 19... |
[
"Is it possible for a solar system to have two planets of the same size within the habitable (Goldilocks) zone?"
] | [
false
] | I’m reading some science fiction where two earth-like planets of the same size are only slightly outside of each other’s orbit, and have similar orbital periods. So similar life forms move back and forth between each planet. I wasn’t sure if this is possible. Would the two planets just collide? | [
"Its absolutely possible to have two earth sized planets in the habital zone, but they need to be in stable orbits, meaning that theyd need to be a minimum distance apart, or gravitational interactions would eject one body, cause their orbits to become unstable over time, or tear them apart."
] | [
"Sure, take a look at Trappist-1, google yields a good overview.",
"Super tiny system, all those worlds are at less than half the orbital height of mercury and there are three similar sized ones in super close proximity in the habitable band.",
"The why of not colliding is called 'orbital resonance'. I recomm... | [
"Given how vague the habitable zone is then yes. In the Solar system you can argue that Earth Venus and Mars are all in the habitable zone. You can also argue that Io and Europa are in the habitable zone. For these planets (and moons) you can also argue some of them out of the habitable zone. ",
"The habitable zo... |
[
"If we observe a single atom as it heats up, is it possible to tell what state it is in and whether or not it is changing state, or is there no difference at all?"
] | [
false
] | I understand that the state of an object has to do with the bonds between atoms and their potential energy, but this is all between atoms. Are there any differences in the way an individual atom behaves in different states? | [
"The concepts of temperature and chemical phase (e.g. solid, liquid, gas) do not apply to a single atom. Rather, they describe how multiple atoms are interacting with each other. In a loose sense, temperature is a measure of the average random kinetic energy of the atoms relative to each other. The \"average\" part... | [
"You are correct in that the thermodynamic state is characterized by the inter-atomic interactions of a collection of matter. But an isolated single molecule can reasonably be considered to be in the gas state for temperatures far enough away from absolute zero. Gas behavior is extrapolated from the summation of a ... | [
"Not sure what you mean by \"state\" in the context of a single atom. If you add energy to a single atom, all you can say is that it's flying around more quickly (or, depending on the energy involved, that its electrons are in higher energy levels). The latter can lead to emission of electromagnetic radiation - vis... |
[
"Light Reflection : To maximize bedroom light, do I turn the bathroom light on or close the bathroom door? [w/ Diagram]"
] | [
false
] | (All the walls and doors are painted off-white) I've been wondering about this for a while. I like my bedroom to be really bright when I'm reading at my desk. I have a few lamps and an overhead light that I turn on. Now, if I want to maximize the brightness in my bedroom, which should I do: (1) turn on the bathroom lights and open the bathroom door; or (2) close the bathroom door? Obviously it isn't going to make a lot of difference either way, but I've become really curious about how the problem could be solved using science+math. | [
"Well, this is a problem that can only really be solved by experiment! Especially since we have no idea about a lot of the factors involved (the exact geometry of the rooms, the exact optical properties of the paint/wallpaper, etc etc). ",
"The simplest way to measure I can think of would be to use my DSLR with... | [
"yeah, this is a cool idea. If you have a light meter, it might also be possible to simply place it on your desk, record the lux, and then repeat that with the bathroom door open and see if you observe any difference in light intensity."
] | [
"try putting mirrors behind both your 55w bulbs, and one on the bathroom door, leaving it open. this will maximize your lighting. "
] |
[
"If your car is on a steep hill or towing something heavy and you push on the gas pedal but the car doesn't move, where is the energy going?"
] | [
false
] | [deleted] | [
"If he has an automatic transmission, a large deal of the energy would go into heating up the torque converter."
] | [
"This situation is very much like pushing on a wall with a firehose. If the wall does not move, all the energy stays in the water as it splashes about and knocks other things over. In the situation with the truck, all the energy goes into heating up: gasses exiting your tailpipe, the engine, and the transmission."
... | [
"The torque converter, mostly. The torque converter in your car translates the spinning of the crankshaft, which is what your engine spins, to the driveshaft, which is what spins the wheels",
". The torque converter is filled with fluid, so what happens is that the crankshaft spins the fluid, and then the fluid s... |
[
"What is it about eukaryotic cytoplasm that requires mRNA to be capped and tailed vs. a prokaryotic cytoplasm which does not have such protection?"
] | [
false
] | [deleted] | [
"Good question. It's not that the eukaroytic cytoplasm is more or less toxic to mRNA -- it turns out that getting mRNA from genome to ribosome can be quite a feat no matter how you slice it -- it has more to do with the nature of eukaryotic and procaryotic cells themselves. 5' capping is a handy way for a eukaryoti... | [
"Mitochondrial genetics is, I think, a kind of bizarro world where things tend to resemble nuclear genetics in some ways, but in other ways are totally off-the-wall. I don't want to write another wall of text, so I'll just bottom-line some stuff. ",
"Mitochondrial RNA doesn't need to get transported, so there's n... | [
"All true. I would like to add that the 5' cap is necessary for recognition by the ribosome and binding by the EIF4E binding protein in order to initiate translation. The 3' polyadenylated tail is necessary for transcriptional termination of mRNA, and the cap and tail bind together to make the mRNA circular in the ... |
[
"Why is fire red/orange?"
] | [
false
] | Why is fire red/ orange? Does it have something to do with the makeup of the materials that are combusting? I know that some gases, when burning, come off as blue or even clear at the base then turn to the stereotypical red/orange. Any input is appreciated | [
"Yes but that's not all. This is true for example why Sodium ions color a flame orange, or barium does a greenish color.",
"Flames can also get colors by not fully burned material in the air which emits light based on it's temperature (Incandescence), just like a light bulp does. Because of this you can often est... | [
"Yes but that's not all. This is true for example why Sodium ions color a flame orange, or barium does a greenish color.",
"Flames can also get colors by not fully burned material in the air which emits light based on it's temperature (Incandescence), just like a light bulp does. Because of this you can often est... | [
"To expand on this, incandescence is the dominant mode of light emission in most everyday flames (e.g. candle, campfire, car exploding on TV). The dominant source of incandescent light is soot particles, which reach high temperatures in the flame and emit (typically) red/orange light. Soot is excess unburned carbon... |
[
"Do humans share a similar brain \"wrinkle\" pattern, or is it like fingerprints where each person comes out with a distinct pattern?"
] | [
false
] | So I was reading 'The Dragons of Eden' by Carl Sagan, a book in which he devotes a lot of time studying the evolution of brains. The random thought presented in the title of this post popped up as I was reading but I haven't been able to find an answer with my google-fu. Thanks in advanced! | [
"The wrinkles are called \"sulci\" and the ridges of brain are called \"gyri\" (see top image ",
"here",
"). The folds are similar between human brains and each have specific functions. For instance halfway back on the brain from side to side is the central sulcus. In front of that is the precentral gyrus which... | [
"Exactly, it increases surface area of the cerebral cortex, which is where our \"higher functions\" take place. This is most pronounced in humans; if you look at say, a sheep or rat's brain they will be much smoother."
] | [
"Because of the architecture of the brain. Have a look at ",
"this cross section",
". The cortex is the grey edge around the outside. Grey matter is what does the processing because it has many neuron cell bodies in it in a particular arrangement. Inside that is white matter which contains axons which transmit ... |
[
"Why do like charges repel and opposite charges attract?"
] | [
false
] | I'm also asking the question from a physics point of view (QED) despite the chem tag | [
"This answer is circular. One state is stable relative to another because work can be done by going from one to the other. Work can be done because of the force acting to draw the system towards a lower potential energy. Potiential energy and conservative forces are different ways of expressing the same concept, so... | [
"And now the big question, what is spin? Or should I make a whole new post about it? "
] | [
"A really technical answer is that for any force mediated by a spin-1 particle, like charges will repel while opposite charges will attract. This fact can be proved in quantum field theory. Electric forces are mediated by photons, which are spin 1, so like electric charges repel and opposite electric charges attrac... |
[
"Who came up with the Order of operations like multiplication bevore substraction/addiditon? And why does it make sense?"
] | [
false
] | 2+3*4 = 14 and not 20. Who came up with it it, why does it make sense? I never really asked that question, always accepted it as a fact, but lately I've been asking that questions. Why is 20 wrong? Who says? | [
"PEDMAS and heuristics like it convey the idea of unsaid parenthesis sets we've decided not to write to save ink and space. ",
"(2+3)*4 is 20 ",
"2+(3*4) is 14 ",
"If everyone in the room agrees to follow a certain order of operation convention, you can skip writing parenthesis, if not, make sure to write ... | [
"BEDMAS/BODMAS/PEMDAS or whichever acronym you decide to use are not hard, set rules of mathematics; rather, they're designed to provide a common format for incompletely notated equations.",
"For example:",
"2+3*4 = 14",
"and ",
"2+3*4 = 20",
"are both correct equations. It is only because the equation is... | [
"It is worth mentioning that there are other conventions. So-called ",
"Polish notation",
" and its cousin ",
"reverse Polish notation",
" are designed so that there is no need for parentheses ever."
] |
[
"How are we able to find planets light years away but are still finding dwarf planets at the edge of our solar system?"
] | [
false
] | I just saw a post where a new dwarf planet was found at the edge of our solar system. Should we not have found all these by now since they are closer and we are finding planets light years away. Is it not easier to find these closer celestial bodies? | [
"Planets far away from our solar system are usually not found directly but rather indirectly. They are found by calculating the periodic dimming of the light of the star they are orbiting. When a planet travels better us and the star, we can measure the drop in it's brightness and estimate the size of the planet. ... | [
"For a couple of reasons.",
"They can have a measurable influence on the star or the starlight we receive: While they orbit the star the star also moves a bit as reaction, this can be measurable. Alternatively the planet might pass our line of sight and block parts of the starlight for a while. Most planets are f... | [
"I think planets that are light years away are found by their association with a nearby star. Local dwarf planets are more difficult to find because they are relatively solitary; even though they are orbiting our sun, from the earth's perspective they are in the blackness of space instead of circling a star. "
] |
[
"Skin Color question"
] | [
false
] | I have always understood that it is predicted that human beings first developed out of Africa (Fertile Crescent, Mesopotamia, Etc) and I was wondering what gave the rise to skin color? Did the changing skin color help is adapt to new weather patterns throughout the ages, and is that why Nordic people have lighter skin (colder weathers) and why people closer to the equator developed darker skin? Also, if it was just a tan, there would be no genetic modification (would there?) so there was no chance of passing on your "modified" skin color through reproduction, and therefore what caused distinct skin colors? I hope my question is properly constructed and that you understand what I mean. Thank you askReddit :) Thank you for the overwhelming response. It had really bugged me for a bit to figure out how it had all occurred. That you cited everything has given me a little bit of reading material and I'm enjoying every little bit of it. Thanks once again Wow, this blew up! Thanks everyone for your responses! It is helping me to understand the issue greatly, I just expected a simple answers. You guys are too good<3 | [
"It is simple natural selection, maximizing the amount of vitamin D synthesized, and minimizing any potential damage to the DNA in the basal layer of skin cells. For example, in Africa, there is incredible amounts of ultraviolet light, so African natives have been selected for very dark skin. The large amount of me... | [
"Great question. The fact is Inuit people are lighter in skin than their ancestors but only slightly. This is because they get their vitamin D and folic acid from fatty rich sea food diets, so the selection pressure for lighter skin is far less as there is not nearly as high a requirement for the ultraviolet cataly... | [
"Why then do people in the far North (I'm thinking about natives I've seen in the Canadian north) have dark skin as well?"
] |
[
"Why does metal sometimes look so rough and \"powdery\" on the inside when it breaks?"
] | [
false
] | I noticed this most recently on this corkscrew/bottle opener that snapped. I would have expected it to be smoother and more shiny, even if not quite as much so as the polished surface. | [
"Metals are crystalline, but the metals we work with typically are not in the form of nice chunky crystals but are composed of many many small crystal grains. When a metal piece breaks, the exact surface of separation will propagate randomly between these grains which results in the rough surface."
] | [
"Hey there! What you've just described is called intergranular fracture, and is distinct from microvoid coalescence, which is what is causing the particular texture that OP is showing. Intergranular fracture is more common with high strength steels, and results in crystal facets being shown on the fracture surfa... | [
"A metalugusit will have a better answer I just beat and weld on the stuff occasionally. Cast metals have a granular crytaline structure as it's a one and done process where molten metal is poured into a form or mould. Processes steel goes through a series of processes involving heat and pressure to refine the cry... |
[
"[Neuroscience] Is there a difference in language comprehension depending on which ear we listen with?"
] | [
false
] | Both Broca's and Wernicke's Areas are on the left hemisphere of the brain, so is there any detectable difference in our ability to comprehend language depending on which ear hears the words? I imagine any differences must be slight, but do any exist? Also, follow up question: What about people who have had their corpus callosum severed, and thus don't have as much communication between hemispheres of the brain? What happens with language comprehension then? | [
"Yes, differences in comprehension do exist if you isolate the message to one ear. In right handed people and most lefties, verbal information entering the right ear (which sends signals to the left hemisphere) is more easily processed than information entering only the left ear. ",
"If you cut the corpus callosu... | [
"Aren't people who get their corpus callosum cut abnormal in the first place though? How generalizable are results from experiments conducted on people with ",
" otherwise untreatable severe seizures?"
] | [
"Thank you for clarifying! I'm not sure where I got the schizophrenia thing from, now that I'm trying to look it up. I think I may have learned at some point that schizophrenics have an abnormal corpus colossum and then got that mixed up with the seizure treatment and lobotomy as you say."
] |
[
"Why is a real string pitch depending on the wave amplitude?"
] | [
false
] | When you pick a string on, say, a guitar, with exaggerated force, you may notice a higher pitch, then rapidly decreasing to the expected one when the wave amplitude decreases. This pitch shift is especially noticeable on the lower strings (where larger amplitudes are possible). What is the physical phenomenon leading to this? How can one express this dependence between pitch and amplitude mathematically? Edit: This is not about higher harmonics. There is a small but perceptible shift of the fundamental towards higher frequencies. My guess is that the deformation applied to the string increases the tension, which in turn increases the wave frequency. Is this a possible explanation? | [
"Because the tension in the string is a function of the amplitude. This is because the tension is nonlinear with amplitude. As the string is moved further from the relaxed center position, the tension increases. Tension is part of the equations describing the frequency. That is why in stringed instruments they have... | [
"Tension is nonlinear with amplitude, but itnis more of a \"state\" and not a property. The core of the nonlinearities lies in material properties that change with deformation amplitude."
] | [
"The tension in a string - or any vibrating metal - depends on many properties including stiffness of a material: how much it deforms under a given pressure. Anther factor pertinent to your question is the shape (cross sectional area for a string) of the metal/string.",
"For small amplitude oscillation, these p... |
[
"If some animals can emit light, can they emit other forms of electromagnetic radiation in useful ways (obviously, excluding infrared as escaped heat)?"
] | [
false
] | null | [
"So there's a lot going on here. I'm a physicist, not a biologist, so I'm going to talk mostly about the physics involved.",
"Visible light is very useful as a sensory medium because the spectrum of the sun peaks in the visible region. So the world is nice and bright in those wavelengths, at least during the day.... | [
"There's another physical problem that you didn't mention, which is that UV light tends to damage cells. Our biology usually tends to block UV instead of using it, because the biological cost of using it isn't paid back. But some hunting birds have developed regenerating retinas so that they can see the reflections... | [
"Insects can see UV too, right? What do they do, uh, have disposable eyes? Or do they grow back? Or are they less prone to damage?"
] |
[
"Weird visual/ auditive effect when I watch TV or the computer screen too long."
] | [
false
] | null | [
"Do you have a sensitivity to light and sound?"
] | [
"Nothing apart from this phenomenon."
] | [
"\"The longer I keep the effect up the larger, louder and faster everything seems.\"",
"Does that mean you control the effect? I don't know what it's called or what it means, but I've had the same experience a few times too..."
] |
[
"If you clear your nose often will your nose run more in the long term?"
] | [
false
] | I.E Does your brain compensate for an abnormal mucus loss? | [
"Wow, not much traffic on this question. I'll try to throw my (lightly researched) 2 cents in.",
"This",
" and ",
"this",
" will tell you how mucus generally helps keep the nasal and airway tissues from drying out, among other things (trapping irritants and such). Obviously this doesn't tell you whether blo... | [
"I think the interesting thing would be the brain's response (if any) to the dry nasal passages. I would like to assume it just results in more mucus produced, because that feels accurate in an anecdotal sense... but yeah, if somebody could science this up it would be helpful."
] | [
"oh yeah not really looking for medical advice. Was interested to know how the brain deals with this particular situation. Kinda like the brain getting used to paracetamol you know?\ncheers though man!"
] |
[
"When someone has some kind of head trauma what is it about keeping them awake that can keep them alive; and vice versa?"
] | [
false
] | null | [
"It doesn't keep them alive as such. If I understand it correctly when you are awake and the trauma worsens you will immediately see it by changing in person's behavior and will be able to do something about it. If you are asleep nobody would notice anything."
] | [
"There isn't anything. That's a myth that you need to keep people awake after a head trauma. There's nothing about falling asleep or unconscious that will cause more damage to the person than would otherwise be caused by the injury. You can see how the belief would arise though, the patients people were able to kee... | [
"To add to this, sometimes it’s actually ",
" for people to be unconscious with head injuries. Which is one reason why medically induced comas are a thing."
] |
[
"'Planetary Sci.' Why are the Pacific and Atlantic sea levels different if they are all connected? The difference between the two at opposite ends of the Panama canal can be as much as 20 feet."
] | [
false
] | null | [
"It's all about ",
"currents",
". Currents run east to west on both sides of the Panama Canal, so the water piles up on the east side and is pulled away on the west side. "
] | [
"Wouldn't it also have to do with global tides as lunar gravity pulls more water towards it?"
] | [
"But if you dug a canal straight through, what would happen ?"
] |
[
"Why is it better to wait until food cools down before refrigerating it?"
] | [
false
] | Why not just put food in the fridge straight away after it's been cooked (unless you intend to eat it all)? If you leave it out to cool down first, one might concur that this would give germs more time to multiply on the food. | [
"In most cases it isn't better to let it cool down. ",
"Here",
" is a paper which looked at hygiene practices and compared to reccomendations. Here is a relevant section:",
"Putting warm food in the\nrefrigerator increases energy consumption and causes\ncondensation inside the refrigerator. However, the food... | [
"What do you mean you don’t reach 140 significantly faster? The rate of heat transfer by convection is directly proportional to the difference in temperature of an objects surface and its environment. The fridge has a lower environmental temperature and heat transfer will occur more rapidly as a result. The fridge ... | [
"What do you mean you don’t reach 140 significantly faster? The rate of heat transfer by convection is directly proportional to the difference in temperature of an objects surface and its environment. The fridge has a lower environmental temperature and heat transfer will occur more rapidly as a result. The fridge ... |
[
"What kind of DNA damage is not fixable by the cell?"
] | [
false
] | if any? | [
"I think that the ability to repair DNA damage is a function of enzyme availability.",
"If there is more damage than available enzymes there will be portions that will remain unrepaired. ",
"Other than that I think that only particular cell states will determine the unrepairability of DNA, like senescence or ap... | [
"Thanks for your response!",
"Because you hit on the root of my question (senescence) I have a two forked response. When you say if there are not enough enzymes then damage will remain, does that mean injecting enzymes will solve the issue? I'm not suggesting that's simple (is it?) because each cell would need th... | [
"Regarding the first question, a lot of DNA damage repair events are replication dependent, so unless you de-senesce a cell there will still be areas of the DNA left unrepaired. ( I am going to post this and go back to the second question, I totally forgot what it was)",
"I'll be back!",
"Hmm the non telomeric ... |
[
"Is it possible that a good portion of the cancer today was caused by all the radioactive products created for the public back in the 50's?"
] | [
false
] | I had a thought the other day when I was reading an article on Cracked about all the radioactive products. And, I know radiation causes DNA damage so I put 2 and 2 together...is there any connection between the DNA damage over 50 years ago and cancer today? | [
"I dont have the fancy flair on Askscience, but I have worked as a biostatistician and the more likely \"cause\" of the increase in cancers is extended length of life from other medical care and better diagnostic equipment. I have actually worked on data for these types of arguments.",
"Our life expectancy is ve... | [
"Great post. One thing worth reiterating is that cancer risk becomes much higher the older you get. This is supported by numerous theories of carcinogenesis. In the DNA mutation model, a cell becomes cancerous when it accumulates several (~7-10) mutations in a handful of traits that control cell division - ",
... | [
"I think the down votes are because your point is misleading in the extreme and therefore bad science. Did you bother to check how much polonium is in a pack of cigarettes? Is it enough to matter? I did.",
"A cigarette contains about .04 picocuries of polonium-210. The maximum safe level is about 30 nanocuries. S... |
[
"When we get sick with the common cold, what is actually happening to cause the symptoms?"
] | [
false
] | ie. Why does swallowing become painful? Why does our nose end up getting blocked? (And why only one nostril?). etc | [
"The virus doesn't, rather your own body causes this as part of it's attempts to fight off the infection. Almost all symptoms of an infection result from your own body's attempt to fight it off. It's unpleasant, but biologically preferable to death.",
"I'm not qualified to properly explain the specifics."
] | [
"Common cold is usually caused by a viral infection. The viruses cause inflammation of the nasal mucous membrane with swelling of the membrane and outpouring of mucous , thereby reducing the calibre of the passage and blocked nose. If the pharynx at the back of the throat is inflamed and congested, the nerves carry... | [
"That makes sense, as a follow up question:",
"Why does the virus cause the mucous membrane to become inflamed?"
] |
[
"Ask Anything Wednesday - Engineering, Mathematics, Computer Science"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Please only answer a posted question if you are an expert in the field. . In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for . If you would like to become a member of the AskScience panel, . Past AskAnythingWednesday posts . Ask away! | [
"There are multiple problems with computers right now:",
"So we have a limit to transistor amount and frequencies. AMD currently circumvents the transistor limit by glueing multiple dies on one chip on their Workstation and server cpus and is researching how to do that with their gpus aswell. Chiplets bring anoth... | [
"How fast are we approaching what's physically possible with computer systems? Gpu's and Cpus's are steadily getting better and better and smaller and smaller, but I'm sure that similar to cars, were going to hit a brick wall at some point where you physically can't cram anymore inside a space without significant t... | [
"What, physically, are the defects you mentioned in your second point? Are they something that will eventually be (mostly) eliminated as the tech matures? To what extent are they feasibly avoidable?"
] |
[
"How can our bowels selectively pass either gaseous or solid/liquid contents?"
] | [
false
] | How do muscle contractions selectively act on gasses as opposed to more substantial contents? Is this similar to how one can burp without expelling gastric juices? I apologize for the shitty question, but not for the pun. | [
"To move fecal matter you use persistaltic muscle contractions in your intestines, for gas these movements are either minimized or not present-releasing gas compared to a solid is much easier. The body has many sphincters, which is something that just constricts an opening. For a sphincter to pass gas it doesn't ne... | [
"Moreso mechano/stretch receptors in your rectum and anal sphincters that signal whether or not you need to poop or pass gas. Funnily enough, it gets tripped up from time to time, which is why people tend to have accidents. You also tend to pee a bit when you defecate because your urinary system uses the same rec... | [
"Moreso mechano/stretch receptors in your rectum and anal sphincters that signal whether or not you need to poop or pass gas. Funnily enough, it gets tripped up from time to time, which is why people tend to have accidents. You also tend to pee a bit when you defecate because your urinary system uses the same rec... |
[
"Thought problem: looking into a mirror"
] | [
false
] | I came up with a little thought experiment the other day. Lets assume you have a perfectly circular mirror (a mirror that reflects back an identical and completely undistorted image), and you looked directly at it. If you then spun this mirror very fast (lets say 1/10, 1/2 or even 99.99% the speed of light) what would you see? Would your image looked skewed or exactly the same? | [
"There is no evidence to assert this claim. It is highly possible that the image might be skewed at speeds around .9999C because locally the atoms have a tangential velocity. Electrons in the atoms of the mirror absorb and re-emit the photons. There has to be something deeper happening than ",
".",
"While norma... | [
"I think one problem that this thought experiment describes is the problem we have resolving relativity with quantum phenomena.",
"Doubtful. In this case, gravitational effects shouldn't be considered for simplicity's sake. Quantum mechanics can be used with special relativity without the problems encountered wit... | [
"Since it takes a nonzero time for the photon to be absorbed by the material and then reemitted wouldn't the mirror have shifted a bit in that time (assuming we can spin it arbitrarily close to ",
")?"
] |
[
"Does thinking really hard use measurably more calories?"
] | [
false
] | [deleted] | [
"Depends what you mean by thinking really hard.",
"Your brain is functioning at all times in some manner or another. I'm assuming you're referring to higher functioning in the sense of thoughts and images and sounds being relived through memory, the issue with that is we don't exactly understand how that comes ab... | [
"Depends what you mean by thinking really hard.",
"How about \"flow\" or intense concentration? Like when doing a math exam.",
"Also, is it possible that amount of blood flow is somewhat beside the point? Are there differences in the brain's utilization of blood glucose, e.g. measured as ",
"? Mind you I'm so... | [
"One anecdotal story is not science, sorry. See sidebar note on \"free of anecdotes\"",
"Also, just to napkin sketch losing \"a couple of pounds\" in a weekend is ~7000 calories over (2) 12-hour days, or 300 calories per hour. This is not a totally unreasonable amount of energy to expend (comparable to brisk w... |
[
"Genome wide association studies and SNP data interpretation."
] | [
false
] | Genome wide association studies use SNP data from the entire genome sequence of study participants to identify particular SNPs that are strongly associated with a disease state (in my example study Type II Diabetes and triglyceride levels). Those SNPs can be used to identify nearby genes that are likely associated with the disease. This is because it is not likely that there will be recombination between the nearest gene and the SNP. What I don't understand is why there are SNPs located within the gene and between the gene and the SNP that was associated with the disease that are not associated with the disease. How can one SNP be associated with a particular allele of a gene that causes disease, while the intervening SNPs are not associated with the disease? The introduction of the concept of haplotypes and their association to SNPs further complicates my understanding of SNP association to gene alleles. How can one haplotype be associated with a disease and the SNP alleles within that haplotype not be associated? An example for those of you that have institutional access: More clarification: I assume at one point there was a haplotype containing the first mutant allele of a gene that contributes to disease and specific alleles at the surrounding SNP loci. What genetic events could occur that would alter the surrounding SNPs such that an SNP 2kb downstream would be associated with the disease while the intervening SNPs are not? | [
"This is largely a question of statistical power. Consider the following three SNPs. SNP X/x causes the disease if you have allele x. SNP Z/z was found to be linked to the disease. SNP Y/y occurs between SNPs X/x and Z/z, but was not found to be linked to the disease. There are four haplotypes: XYZ occurs in 93% of... | [
"Thanks for that! I always wondered the same thing as OP."
] | [
"Thanks, but how do the intervening SNPs (in your example SNP Y/y) arise? The only scenario I can think of is that SNPs that are correlated with disease arose from a point mutation shortly after the disease allele of the gene they are associated with was created, such that the associated SNP allele traveled with al... |
[
"If we're creating so much carbon dioxide, what keeps us from creating a photosynthesis machine to get rid of it?"
] | [
false
] | This is a question that's been bugging me for awhile. Maybe the science is too technical and we're not there yet, but I'd like to know whats keeping us from doing it. If you look at a basic for photosynthesis, it shows if we take some carbon dioxide + water + sun = oxygen and sugar. Why can't we do the same thing and start pulling carbon dioxide out of the air ourselves? Thanks! | [
"Considering the amount of energy involved, it would be far more efficient to simply plant more trees. As a bonus, you mitigate problems with soil erosion, ecosystem destruction, etc."
] | [
"This is a relatively old ",
"article",
" but it explains the difficulties involved in creating artificial photosynthesis. "
] | [
"Leaves on trees are green because that is the part of the spectrum that has the largest intensity from the sun's radiation. Unfortunately, that part of the spectrum is the least efficient portion to convert to energy. Think of it like you are in a dry climate and you want to store water in your house from a rare r... |
[
"Is it possible to harvest electrical energy from plants?"
] | [
false
] | Aside from the obvious potato or lemon batteries, but for the possibility to harvest electricity from an oak tree and how much could it generate? | [
"A lot of people seem to not properly understand how these batteries work. The lemon or potato don't actually \"have electricity\" in them. Rather their \"juices\" act as electrolytes that allow for the transfer/flow of electrons from the zinc-copper diodes* that are needed for these to work. You can actually repla... | [
"Burn plant matter as fuel for a generator. ",
"Anything that can burn can be used to generate electricity. "
] | [
"Lemon batteries can generate voltages of about 0.9V. ",
"According to Guinness, the highest voltage ever recorded from a potato battery (which consisted of 1,000 potatoes) was 538.1V",
"http://www.guinnessworldrecords.com/records-7000/highest-voltage-from-a-potato-battery/",
"These voltages are very low. It ... |
[
"When did life evolve sleep?"
] | [
false
] | As a secondary question, which modern animals don't sleep? Why? | [
"This is kind of a weird question to ask, since it all comes down to how you define sleep. Most organisms, including unicellular organisms like bacteria, show a 24-hour cycle of rest and activity. These 24-hour cycles are driven by some sort of internal circadian rhythm, and their purpose is to address both externa... | [
"Just to add to the invertebrate section, at least one ",
"jellyfish species",
" is thought to sleep (arguably), despite not having a brain (it uses a nerve net). It definitely fulfills criteria 1, 2, 5, and 6, and it's not clear 3 and 4 could possibly apply to a species that basically has one posture and one b... | [
"I'm not sure that's a change of concept so much as a change of how information is indexed."
] |
[
"How do emotions trigger tears?"
] | [
false
] | I know that stimulants and irritants can stimulate the tear ducts to secrete fluid, but how do emotions do the same thing? | [
"Your body produces different types of tears. The ones that irritants make aren't the same as the ones that you create through emotional response.",
"Emotional tears contain prolactin, corticotropin, Leu-enkephalin, and trace elements that are not found in reflex tears (which are 98 percent water). These hormones... | [
"where would that 98 percent of water come from?"
] | [
"They all come from the same place, the lacrimal glands and the conjunctiva perform active excretion. These glands are able to formulate various concentrations of substances as needed for lubrication, removing irritants, or discharging abundant proteins."
] |
[
"Knowing that water expands when either boiling or freezing, is there a temperature at which it takes up as little volume as possible?"
] | [
false
] | [deleted] | [
"+4C.",
"Above that, it expands with heat. Below that, it expands as it starts to form into crystal lattices."
] | [
"Just want to add that this assumes standard pressure (as does the OP's question)"
] | [
"Assuming you're talking about its liquid form, 4C or 39F. At this temperature water has the highest density, and since d=m/V, the volume will be the smallest."
] |
[
"What is so special about \"prime numbers\"?"
] | [
false
] | I understand prime numbers and pseudo-prime numbers have applications in cryptography, precisely because it is difficult to determine what a particular unknown number's factors are, if any. However, what is really so fundamentally special about prime numbers? There seems to be an air of mystery around them, and I'd genuinely like to understand this. Thanks! | [
"Prime numbers are special because they form a sort of basis for natural numbers: you can describe all natural numbers by their decomposition into prime factors (eg: 15 = 3 * 5). This decomposition is unique, and importantly for the cryptography application, is very hard to find for big numbers (you pretty much hav... | [
"There are a -lot- of primes. For example, we can approximate the number of primes smaller than n by n/ln(n). RSA public keys are typically at least 1024 bits large. Making some gross approximations (2",
" ~ 10",
" we get there should be about 2*10",
" primes or roughly 2",
" primes. ",
"So even if you ha... | [
"For example - we can take two large primes, say 100 digits each, and multiply them. The number we get from this can be the public key --- or what people use to encrypt their messages. They can encrypt in such a way that to decrypt, one would require the two original primes we used to create the key. Since they are... |
[
"Why is it that when you're in a \"dark\" room and you focus on a really dark spot, everything, even light, will start to fade away?"
] | [
false
] | I know I probably didn't make any sense since it's hard to explain but imagine being in a dark room with nothing but a little red LED light in the center of the room, if you focus on a dark corner you can see how this light will fade away into darkness. Why is that? | [
"What you describe is an example of Sensory Adaptation. Through the process of sensory adaptation, our sensory systems become less sensitive to constant, unchanging stimuli. ",
"In your scenario, if your eyes remain motionless, what little light is present will continually stimulate the same retinal photoreceptor... | [
"Yes. The photopsins in your cone receptors photobleach when stimulated and take time to regenerate. So, if the same cones keep receiving the same light signal, the photopsins will bleach out faster than they can regenerate and that part of your eye becomes more and more insensitive to that color. When the image sh... | [
"Is this the same concept that’s in play when you stare at those inverted color images for x amount of seconds and then look away to see the image in color? "
] |
[
"What would modern cars look/perform like if occupant safety was not a design factor?"
] | [
false
] | null | [
"How do I move it?"
] | [
"A good home for this question is ",
"/r/AskScienceDiscussion",
"."
] | [
"Just make a new post."
] |
[
"Do animals ever get zapped by \"static shock\" in non-human made environments? Or is getting that static shock a byproduct of human engineering?"
] | [
false
] | It seems like all the times that I've ever gotten a static shock, I was in a human made environment where there was carpet, or a car, or a door knob. Now, I'm not saying that animals could never get a static shock, I know it's just the passing of electrons, but I'm wondering, are there are any natural environments that are conducive to creating that build up? EDIT: So I'm still a little confused as the "of course it happens" posts often are not taking into account man-made fibres and contexts. It looks like it might happen more often in winter since it is drier, and would be more likely if the animal was not touching the ground (so in a tree with lots of sap and resin maybe?), however since most animals are touching the ground a lot, the build up necessary wouldn't happen nearly as often. | [
"Furry animals in dry environments generate static electricity all the time. Pet an outdoor cat in winter, and you'll hear the crackling."
] | [
"Unless anyone came up with a specific example, then I'd say no. ",
"For a static shock to occur, two materials on opposite ends of the ",
"triboelectric series",
". need to come into contact. Most biological environments are made up of materials on the positive end of the triboelectric series (air, skin, hai... | [
"Good call on the amber. Around 600 BCE, in Greece, a mathematician named Thales discovered that amber rubbed with animal fur attracted light objects. This was the first known discovery of static electricity. "
] |
[
"Who is the human holotype?"
] | [
false
] | Is there a specimen of Homo Sapiens that was used when it was formally described? | [
"QI did a section on this: ",
"http://www.youtube.com/watch?v=xpRksEo4Q8k",
"To summarize:",
"Edward Drinker Cope was going to be, but then they found he had syphilis ",
"http://en.wikipedia.org/wiki/Edward_Drinker_Cope",
"Currently, there is no human holotype."
] | [
"I bet Marsh was ",
" when he found out they were planning on using Cope"
] | [
"No. Or not when I last checked. The person who described humans (or something) WAS going to be it, but it was found he had syphillis or something "
] |
[
"Why is there a limit to how far back humans can remember?"
] | [
false
] | For example, why can't we remember learning to walk, or speak, or virtually any of the first few years of our lives? Does it have something to do with incomplete neurological development? | [
"The lack of the proper use of the word 'you' makes it extremely hard to take you seriously. :( other than that, your response sounds valid to me."
] | [
"Well memories are basically reinforced neural pathways that are maintained so that u can replay the same sequence again. This is useful because it allows u to remember where u stored the milk, or where u can go buy bread. Stuff like that is used every day, so you reinforce it more and more by playing the sequence ... | [
"As with most things neurological, we don't really have a clear understanding of the limits of neural circuits, and guessing why something evolved over time to be the way it is usually leads to either an unsatisfying level of generalization, or unscientific speculation. That being said, you might be surprised to kn... |
[
"Any update on theories on how will universe end?"
] | [
false
] | In an "askreddit" thread on what will happen after death, someone did post an insightful quote on how our atoms will be here forever, and this leads me to reflect on the few theories I did read here and around the internet on the end of the Universe, mostly about the so called "heat death". When looking around in this sub, I did realize that the few threads on the matter are few years old, and I was wondering if more recent studies did change our perspective, or maybe made more solid one of the few theories. Thanks for any reply. | [
"Since the accelerating expansion of the universe was first discovered in the late 90s, we've really just got more and more precise in measuring this acceleration of the universe - there's no indication that it isn't actually accelerating. So the \"heat death\" is just being increasingly confirmed.",
"The current... | [
"\"ruled out\" would be difficult to say with certainty, but it does appear vanishingly unlikely. dark energy appears to be a constant energy ",
" of space itself. therefore, as the universe expands, there is more space, and with it there is more dark energy. if dark energy weren't created out of nothing, the den... | [
"Wikipedia has the \"",
"Timeline of the far future",
"\" article which covers many of the possible scenarios and the time when they might occur if our predictions are correct."
] |
[
"Why do meteors burn up on entry into the atmosphere?"
] | [
false
] | null | [
"Friction",
" and compression both play a part. As the atmsopheric particles interact with the surface of the meteorite heat is produced. The more particles interact, the higher the friction. Rub your hands together. Now increase the rate or force of the rubbing - you'll notice your hands get hotter quicker. Sa... | [
"Atmospheric friction is just a simplification for the general public view. (air have v. little fiction)",
"Compression following the gas law is what actually heats up anything travelling through a gas at speed."
] | [
"Sorry to reply to a 6 day old comment, but I figured the subreddit was flooded with meteor questions around now, and this question seems the closest to mine:",
"I understand why things heat up and burn up when entering the Earth's atmosphere, but what is the mechanism behind their exploding before impact? (That ... |
[
"Is it theoretically possible for chimerism to occur between identical twins?"
] | [
false
] | , though I'm not sure whether it would be this or . If something like this did happen, would we even be able to tell since the embryos had identical DNA? Edit: The way I worded the title may be confusing. I meant, "Can a pair of identical twins become a chimera?" And would you even be able to tell if they did? | [
"You would not be able to tell the difference between them if there were. By definition, a mosaic is comprised of two ",
" genotypes. So the situation you describe wouldn't be mosaicism or chimerism, and we wouldn't know if they existed, due to their genetic compatibility."
] | [
"This would be mosaicism. Mosaics come from one zygote, as is the case with monozygotic (identical) twins. Fraternal twins could be chimeras, although the odds of that happening would be much smaller likely than mosaic monozygotic twins. And ",
"yes",
" it has happened. They can test via blood sampling."
] | [
"I don't think that's quite what I meant. The article you linked talks about a pair of twins that each had mosaicism; I meant a single person who was a chimera of identical twins. Or does chimerism have to occur before the zygote starts dividing?"
] |
[
"When scientists refer to \"information\" as in \"can information be lost in a black hole,\" what is the information?"
] | [
false
] | [deleted] | [
"quantum numbers. For instance, there's a thing called lepton number. When a neutron decays to a proton it emits an electron and anti-electron neutrino. Why anti? Because you get a +1 lepton number from the electron and a -1 lepton number from the anti-neutrino. And since you had no leptons to begin with +1-1=0 so... | [
"evaporation was the resolution. See we used to think that all of that information was just trapped in the black hole. But now it seems more like evaporation releases the information back into the universe. So to continue with my example, when an electron \"falls in\" its lepton number is recorded on the event hori... | [
"It is literally information, as in Shannon information. ",
"All information is physical, i.e. it must be encoded in something, for example the switching state of a transistor, or even just as lines on a sheet of paper.",
"What remains is to figure out how much information can possibly be carried by a given sys... |
[
"Where/How do we get birthmarks?"
] | [
false
] | [deleted] | [
"We don't know why birthmarks occur. There are two types. Pigmented birthmarks are caused by an excess of skin pigment in the area while vascular birthmarks are caused by blood vessels clustering up. Vascular birthmarks are not hereditary, it's just an imbalance. Pigmented are not necessarily genetic but the condit... | [
"Developmentally, they can be explained by clonal colonies of cells. A patch of cells early in the embryo over express pigment. Later all the cells from this line will express the excess pigment too because something is causing the gene to be up regulated. This could be a minor mutation, or some environmental compo... | [
"I find this amazeing that we do not know why they occur. are you talking in a evolutionary why extent like why would our ancestors have had them or what there.left over from. or are you talking like what use they could of served? "
] |
[
"If the Earth is 4.5 billion years old, shouldn't the oceans have higher salt content?"
] | [
false
] | I understand that the salt content in the ocean is caused by mineral run-off, volcanic explosions, and hydrothermal vents on the ocean floor, and that there's evidence that the current salinity of our oceans was about the same a billion years ago. I've heard those in favor of a younger earth state that the salinity of the oceans is proof that the earth is much younger. I don't know enough about this, and am curious. I've done a few searches on Google, but everything I've found so far is coming from the Creationist standpoint. Would you mind offering some clarity for me, ? : You're the best, . Thank you very much for your input so far. I'm reading and learning as we go. | [
"Salts do enter and form in the ocean, but they also leave it.",
"The two major processes capable of removing significant amounts of salt from the ocean are the formation of ",
"evaporites",
" (rocks that form when restricted, salty water evaporates) and the sequestration of ",
"brine",
" as groundwater o... | [
"Ocean salinity",
"Ocean salinity has been stable for billions of years, most likely as a consequence of a chemical/tectonic system which removes as much salt as is deposited; for instance, sodium and chloride sinks include evaporite deposits, pore water burial, and reactions with seafloor basalts.[11] Following ... | [
"As described by D8M900 and wiki-linked by stubob, the salinity of the ocean has been (relatively) stable for a long time. This is due to the cyclical nature of the addition and removal processes, which is intuitively obvious when you consider these processes have had plenty of time to equilibrate.",
"Truth be t... |
[
"Do the contents of our blood have any affect on mosquitos after they drink it? Do drunk people make drunk mosquitos?"
] | [
false
] | null | [
"I think the answer is, \"",
"we don't know",
",\" but it seems that mosquitoes are more attracted to drunk people, than sober people, and according to the article I linked fruit flies do get drunk, but have a high tolerance. ",
"Same article also says, \"Any liquid other than blood is diverted first to a sep... | [
"Remember than even an extremely drunk person won’t have a blood alcohol content of more than about 0.20-0.30%. You could drink a nearly infinite amount of 0.2% alcohol solution without becoming intoxicated yourself."
] | [
"Train of thought?"
] |
[
"Does a satellite orbiting earth cast a shadow on the earth's surface?"
] | [
false
] | null | [
"More specifically, the umbra cone of the satellite falls far short of the earth's surface, while the penumbra is too subtle to discern with the naked eye."
] | [
"The shadow does not reach the earth's surface.",
"A shadow is not actually straight lines from an object down to the surface, it is actually slightly angled (the sun is much bigger than any object on or near earth, or earth for that matter). These angles are small because the sun is very far away.",
"It is qui... | [
"Imagine yourself on Earth with a satellite between you and the Sun. You are not in the shadow, because the satellite is too small. "
] |
[
"Do hot objects experience time differently than cooler objects?"
] | [
false
] | Temperature corresponds to the average kinetic energy of an object's molecular particles. Objects with more kinetic energy experience time "slower" than objects with less. Do hot objects experience time "slower" than cold objects (assuming both objects are made of the same material, and have the same mass)? | [
"You would have to own an extremely accurate scale.",
"You can do the calcs with iron, with those numbers. I'm too lazy but the steps would be, figure out the amount of heat required, in joules, to change the temperature or 1 kg iron (easy formula). Convert that to MeV. Use 931.5 MeV/ 1 Atomic Mass Unit."
] | [
"No. Hotter objects are more massive, but time does not ",
" slow down with increased energy/mass.",
"All goes back to E=mc",
" If energy increases, the mass does as well. But, in order for time to dilate a formula is used:",
"Δt'=γΔt,",
"where gamma is the Lorentz factor, and t is time. The prime ind... | [
"Got curious.",
"5.563×10",
" kg (kilograms)",
"Would be somewhere around the mass change."
] |
[
"Question about anti matter-matter annihilation?"
] | [
false
] | Does anti matter annihilate with any matter or just with its exact opposite? As in, would antihydrogen be safe in containment of pure carbon for example and only annihilate with hydrogen or does it react to everything? If it does annihilate with all normal matter, what would happen if we pushed antihydrogen to say uranium (or any other really heavy element)? | [
"Does anti matter annihilate with any matter or just with its exact opposite?",
"Just its exact opposite. An antiproton and an electron do not annihilate each other, for example.",
"As in, would antihydrogen be safe in containment of pure carbon for example and only annihilate with hydrogen or does it react to... | [
"Matter/anti-matter annihilation reactions are best understood in the context of laws of conservation. There are many well known laws, such as conservation of momentum, conservation of mass/energy, conservation of charge, etc. There are some other laws that are less well known such as conservation of lepton number,... | [
"in feynman diagrams antiparticles are displayed as going back in time.",
"from wikipedia:\" Feynman used Ernst Stueckelberg's interpretation of the positron as if it were an electron moving backward in time.[2] Thus, antiparticles are represented as moving backward along the time axis in Feynman diagrams.\"",
... |
[
"Can someone explain to me what makes a good or bad nucleophile for SN 2 and SN 1 reactions?"
] | [
false
] | I know that it affected by the strength of it being a base, but I'm still confused by knowing exactly how to figure it out. Being in a summer class my professor flew through it and didn't explain it that well. | [
"Try ",
"this Wikipedia article",
" for some help.",
"Basically, the rate of the reaction is only affected by the nucleophile in the SN2 case, assuming high enough nucleophile concentration. How easily that nucleophile can donate its electrons to the central carbon determine how fast the reaction proceeds. Th... | [
"There are four factors that affect nucleophilicity for an SN2 reaction:",
"1) Bases are better than conjugate acids (another way of saying negative > neutral > positive). The justification is that negatively charged atoms will have higher starting energy and the transition state will have lower energy.",
"2) ... | [
"Okay let me breakdown those 4 types of mechanisms for you clearly and concisely side by side, for reference.",
"Elimination-1 means only one thing happens at a time. First we will have our leaving group bounce, and then our nucleophile will attack the vacant spot in a second step. E-1 reactions are supported b... |
[
"Is it possible to massively accelerate the growth rate of plants?"
] | [
false
] | [deleted] | [
"It depends on how much you mean by \"massively\". You can get a plant to grow many times faster than typical by giving it lots of light of the proper spectrum, nutrients of the right types, CO2 supplementation, and hormones, such as gibberellins.",
"Mind you, making a plant grow faster is a lot more tricky than... | [
"Thank you for your answer! As a follow-up, what do these factors influence in the plant that makes it grow more quickly?"
] | [
"Well, what most of the factors do is remove natural bottlenecks that slow plant growth.",
"If you have a ton of light, then you are limited by the ability of the plant to take up nitrogen and other nutrients. If you have an optimized system that allows the maximum possible uptake of nutrients, then CO2 concentr... |
[
"RIP Kepler Megathread"
] | [
false
] | After decades of planning and a long nine years in space, NASA is retiring the Kepler Space Telescope as it has run out of the fuel it needs to continue science operations.We now know the Galaxy to be filled with planets, many more planets existing than stars, and many very different from what we see in our own Solar System. And so, sadly we all must say goodbye to this incredibly successful and fantastic mission and telescope. If you have questions about the mission or the science, ask them here! | [
"Oh man. The gap between this and James Webb (which appears to be launching in about a year, and that is a fact that appears to remain true independent of what year you're reading this in) is gonna kill me. Bye little buddy. Anybody close to this project have any cool science/mission facts they could share that are... | [
"We now know the Galaxy to be filled with planets, many more planets existing than stars, and many very different from what we see in our own Solar System.",
"I know this will be somewhat subjective, but what do you think is the strangest, most unexpected planet that we have discovered?"
] | [
"I've got two that I'll suggest as strangest objects, though neither fits into the 'planet' category neatly from Kepler discoveries. The former.... could be tied to planets, and the latter may be the remnants of a former planet. More broadly, the goal of Kepler was primarily to understand planet frequency, especial... |
[
"Why do things look darker when they get wet?"
] | [
false
] | Pavement, hair, clothes, everything! | [
"Reflection and absorption. When you see something, you're sensing the light that has reflected off of that thing. ",
"When it's dry, a portion of the light that strikes your target is absorbed by it and the rest is reflected. When there is a layer of water (or oil, laquer, etc) the same thing happens BUT some ... | [
"The reason materials often look darker when wet is that there is decreased back-scattering of light towards the observer.",
"Materials such as clothing and paper and made of fibers with air spaces in between (pavement also has an irregular surface with many air spaces). According to Fresnel's equations, at each ... | [
"You seem to be neglecting transmitted light. If all the light was either absorbed or reflected, then it would not be possible to see diffuse light through a dry sheet of paper or what's underneath a wet t-shirt."
] |
[
"Do people with similar kinds of synesthesia have similar kinds of synesthetic associations?"
] | [
false
] | [deleted] | [
"Us non-synesthetes for the most part see the same colors in the same places, and agree on high and low pitched sounds, etc.",
"We're taught that a particular wave-length of light corresponds to a particular colour. The way that those wave lengths are given off by objects doesn't change because of the person look... | [
"Yes, yes ",
"beetle in the box",
". Still, we don't ",
" the wavelengths, we see the signal the eye gives the brain in response to those wavelengths. And you could say we don't see the signal either, we \"see\" whatever the furthest thing back in the causal chain is that the brain does in response to receivi... | [
"So I have grapheme->color, grapheme->personality and space sequence synesthesias. I just found out this year that these were even a thing - always thought it was my imagination that likes 'a' to be yellow. They are sort of embarrassing to describe so I barely even talk about the grapheme->color, and almost never... |
[
"Does letting a phone battery die completely before charging help improve battery life?"
] | [
false
] | It seems occasionally my phone will start to get a terrible battery life, lasting less than 12 hours, but if I run the battery to zero and let it charge to 100%, the phone seems to last a whole day again. Is this a real effect? If it isn't, why would it seem like a real effect? | [
"Resetting the charging circuit has been covered here. However, you should avoid fully discharging a lithium-ion cell as much as possible.",
"The rate at which a lithium-ion cell is damaged varies based on how far the cell is from its nominal voltage (~3.7V). The voltage limits for your device are chosen to balan... | [
"I thought modem batteries had safety measures in place to keep from ever fully discharging. "
] | [
"ya but due to internal resistance they will self-discharge.",
"The cut off is to stop the terminals from providing current if the voltage is too low (to save space for self-discharge)."
] |
[
"My physics textbook says that small redshifts of galaxies are due to their velocities relative to us, while large redshifts would be caused by expanding space stretching wavelengths. Is it really necessary to make a distinction like this, and can redshift be explained through a particle model?"
] | [
false
] | Thanks in advance! | [
"No it does not. (The other poster is very very wrong) The expanding space solution does not apply for gravitationally bound systems. Here's a look at the concept: ",
"http://arxiv.org/abs/0809.4573"
] | [
"It is indeed necessary to separate the two kinds of redshift. They are actually physically very different. The relative velocity redshift occurs immediately - someone at rest with respect to us who was right next to the galaxy would see the exact same redshift as we see.",
"The cosmological redshift is much more... | [
"Since the relative velocities of other galaxies are proportional to the distance between us and them (",
"Hubble's Law",
"), the redshift of the nearby galaxies are much smaller than that of far away ones. Therefore, the redshift of nearby galaxies could be regarded as a redshift due to the recession of the li... |
[
"Can anything be said in every language?"
] | [
false
] | I know some languages don’t express certain words or concepts. Like English borrowed “rendezvous” among very many others because there isn’t a good substitute. And some languages lack certain color words. And there are probably many more examples. But other than maybe “yes”, “no”, and greeting (and even then I can’t be sure if that’s true), is there any concept that’s universal among languages? If so, what/why? | [
"I listened to a podcast awhile ago about the most universal word understood among languages both now an early precursors to modern language. The word they came up with was \"mama\" and thought it was at least partly due to human vocal development. Basically, mama is one of the earliest sounds a baby can make, so w... | [
"There are certainly words that don't have a 1 to 1 translation. The German \"waldeinsamkeit\" is the experience of being alone in the woods. English doesn't have one word for that, but clearly I can convey the meaning. I would argue rendezvous is is just a specific type of secret-ish meeting. Agglutinative languag... | [
"English has a way to express \"rendezvous\" without using that word, though:",
"a meeting at an agreed time and place, typically between two people.",
"You could just say that whole thing every time you would say \"a rendezvous\", if you happened to not know that word, or had a weird thing against French loanw... |
[
"Why are download and upload speeds in average internet connections so radically different?"
] | [
false
] | null | [
"Simply because most ISPs limit your upload speed to a fraction of your download speed as a cost-saving measure.",
"The idea from the ISPs side is that most of what users want to do is download (streaming music, video, visit web pages, etc.), so they go cheap and limit your upload speed so they don't need as much... | [
"That depends. For the most part, your ISPs equipment will be full duplex; any given router or server at your ISP should be able to run the same aggregate speed in either direction.",
"However, just like you get asymmetric speeds from your ISP, your ISP also buys their capacity from an upstream provider, and th... | [
"Historically, high speed Internet via T1, T3, OC5, etc. Was the same bandwidth up and down. Early cable used the cable wire for down and the slower telephone wire for up, so there was a discrepancy there in the early days. Then along cane DSL which got T1 speeds over twisted pair phone cables — with a catch. To... |
[
"Why are our fingerprints spirals?"
] | [
false
] | null | [
"No one can answer that because No one knows about regularity of fingerprints, because fingerprints are not genetic. All of your finger and toe prints are formed when you’re rubbing the inside of the amniotic sac."
] | [
"The number you present in your argument is binary",
"As the base wasn't specified, it could be in any base, including base 10. As such, it is an example of a repeating number which doesn't contain every possible number."
] | [
"The number you present in your argument is binary",
"As the base wasn't specified, it could be in any base, including base 10. As such, it is an example of a repeating number which doesn't contain every possible number."
] |
[
"Does the DNA scramble randomly?"
] | [
false
] | [deleted] | [
"Yes, this phenomenon is known as ",
"genetic recombination",
" and is quite common - and is arguably the biggest contributor to genetic diversity in offspring. Many mechanisms exist for genetic recombination, including what others have mentioned about homologous recombination of sister chromatids known as ",
... | [
"Well, it's 'random' and it isn't. There is a random shuffle between chromosomes, and also somewhat with chromosomes during crossovers. But, depending how close certain gene loci are together, they will more often be associated with each other. and genes on a certain chromosome, will nearly always (barring weird re... | [
"Well, it's 'random' and it isn't. There is a random shuffle between chromosomes, and also somewhat with chromosomes during crossovers. But, depending how close certain gene loci are together, they will more often be associated with each other. and genes on a certain chromosome, will nearly always (barring weird re... |
[
"How far can a smell travel? Are there ways to figure out where a smell will/is going? Do different odors travel farther?"
] | [
false
] | [deleted] | [
"The inner workings and sensitivity of the olfactory system are beyond me, but \"smells\" and how they travel basically works as follows:",
"Odor compounds are given off by something - bottle of perfume, skunk, rosemary chicken cooking in the oven. What you're smelling are various molecules that your olfactory s... | [
"Also, does odor displace air, or does it infect it and change it? How does it spread on the molecular level? "
] | [
"A smell can travel at least several kilometers. Look up \"The Tacoma aroma\"."
] |
[
"If a 9 hours sleeper sleeps 7 hours a night, are the effect the same as when a 8 hour sleeper gets 6 hours?"
] | [
false
] | null | [
"When it comes to sleep, \"we don't really know\" is usually the best answer.",
"It was only recently that it was discovered that our bodies clean the fluid around our brain during sleep. This may or may not be the primary reason for sleep.",
"In terms of time, we don't really know. Because we don't know what d... | [
"Thought sounds pretty interesting. Can you dig up a source for the fluid-cleaning during sleep? I'd love to read more about that."
] | [
"I actually worked on a study relevant to this! The project itself studied the effects of minor sleep loss (3 hours per night for a week) on speech processing in adults, using EEG event related potentials to speech sounds. The analysis mainly showed that speech processing under minor sleep deprivation involved an i... |
[
"Has a virus ever been cured with medication? If no, why not?"
] | [
false
] | [deleted] | [
"-- Are immunizations possible for bacterial infections? If no, why not?",
"Yes, the anthrax vaccine for example.",
"-- Why are bacterial infections curable with medication, and virus infections not curable, or more difficult to treat?",
"Bacteria are sperate organisms with their own metabolisms and their cel... | [
"this would be depending on what you consider acceptable as \"cure\"",
"There is quite the assortment of antiviral drugs out there.",
"One of the most commonly known ones (thanks birdflu) would be Oseltamivir or more commonly known as Tamiflu. (on a side note H1N1 seems to be resistant against it by know).",
... | [
"Thanks!"
] |
[
"About Einstein-Rosen-Bridges and thermodynamics..."
] | [
false
] | I read an article about in which was stated, that a "white hole" can seemingly "ignore" the laws of thermodynamics. How is that possible I always thought, laws of physics have to be universial, which ultimately is a criterion to be a law of physics. Does anyone have any explanation for this? | [
"One of the main problems in theoretical physics in the 1970s was the black hole entropy problem, where black holes would seemingly violate the second law of thermodynamics if they had no entropy. To solve this problem, Hawking and Bekenstein conjectured that black hole entropy was proportional to the surface area ... | [
"Thank you for that detailed answer could you specify what ",
"a perpetual motion machine of the second kind",
"means?"
] | [
"It is a machine that would be able to take in heat and convert it all to work, thus violating the second law. For example. it would be able to take in steam at 500 K, then release it at 0 K after extracting all heat from it to do useful work. This is impossible."
] |
[
"Correlation between countries age gap indicative of Prosperity?"
] | [
false
] | Countries that have a higher median age tend to prosper more than countries that have a lower median age. | [
"Two things I'd consider is that as education improves people tend to have fewer babies and they have them later. This effects the median age. Also developed nations tend to have longer life expectancies also effecting the age distribution."
] | [
"An interesting idea, but I believe your premise to be flawed. I'll present several cases at the end to show that there is a not a substantial correlation between age and GDP. As you will be able to see, there are a great many other factors which determine a state's economy (area of country, size of workforce, indu... | [
"Correlation vs. Causation. It's the bane of every stats and econ major. Combine them, and you get econometrics!",
"In actuality, this is how economists measure things. Regression analysis gives you hard data on whether certain variables are correlated.(assuming you set up the regression correctly with good data.... |
[
"How are Carbon Nanotubes made into useful things?"
] | [
false
] | So from my understanding carbon nanotubes look like a black powder to the naked eye. How is this turned into string, or rope. How would this be made into a surface like the body of some future car. I don't understand how these microscopic tubes in powder form are made into anything at all. By the way I watched this: Which explained how the powder itself is made pretty well but not how it is made into an end product. | [
"In a lot of cases they're added to traditional carbon fiber composites, such as ",
"this",
" bike frame. "
] | [
"I'd take that application with a grain of salt. To get the strength-to-weight ratio they cite in comparison to normal carbon fiber you'd need continuous carbon nanotubes acting like the continuous fibers of typical carbon fiber. It's an apples to oranges comparison. Carbon nanotubes right now are similar to compos... | [
"Caveat: I'm not a materials expert and not necessarily up to date on the latest in carbon nanotubes. Materials to me are only as good as they are macroscopically useful.",
"How is this turned into string, or rope.",
"Currently, it isn't. At least the last time I read up on what's been going on with carbon nano... |
[
"Is it possible to develop a biological tolerance to allergens via medicine and/or continuous exposure?"
] | [
false
] | Also, is it possible to become immune to certain allergens as a result of this? | [
"It is also possible to become more allergic to something after repeated exposure. In the medical field, this often happens with latex gloves."
] | [
"Short and sweet: Yes, but not always. Works for some and not others."
] | [
"Not necessarily, I don't think there's a ",
" hereditary component to allergies, most of it is environmental and dependent on habits though we still don't have a full understanding of what these cues are.."
] |
[
"Why do pipes sometimes \"resonate\" and create a loud hum when I turn on the faucet a certain way?"
] | [
false
] | I can't really think of any mechanism that would cause this, but fluid dynamics are not my strong point. | [
"A direct application of my thesis work?",
"I'm going to have to email this thread to my mom who can never understand what I do.",
"Anyway....",
"When water forms a free surface, waves form on the surface due to a combination of ",
"Rayleigh instabilities",
" and ",
"Helmholtz instabilities",
" (depen... | [
"Fascinating! Thank you. :)"
] | [
"Possibly - if it does it when the valve is just cracked it's probably the water slugging. Basically the pressure builds up, a slug of fluid shoots out, the pressure drops and the valve slams shut, then the cycle repeats itself over and over. "
] |
[
"Why does coming into contact with a dangerous substance like di-methyl-mercury kill you?"
] | [
false
] | null | [
"Elemental mercury is toxic but what makes mercury compounds such as dimethlymercury so toxic is that it can easily pass through latex or pvc gloves and the human skin. Once it finds its way into the body it will pass the blood-brain barrier. It's not sure how this happens but its presumed because it forms a comple... | [
"It varies from chemical to chemical. Methyl mercury kills partly because it's fat soluble so it can cross into the brain tissue and cause symptoms akin to cerebral palsy. That's not the only effect. Other poisons may affect transmission of nerve signals, prevent oxygen transport to cells or cause paralysis."
] | [
"Would chelation work when the mercury has already penetrated the blood brain barrier?"
] |
[
"How exactly is the second based on the hyperfine structure of the Caesium atom?"
] | [
false
] | I know its based on the electromagnetic transitions in its hyperfine structure, but I have no idea what that means. I've clicked through the different wiki article explaining both, and I just can't quite model it out in my head. Any help would be appreciated! I would also have to think it would be possible to base our second on something else (a comparable vibration/transition of the Hydrogen atom maybe?), and I don't know why we wouldn't outside of it being impractical or incompatible with our current conception of the traditional second. Not sure about any of that, but intensely interested in any responses. | [
"Hyperfine structure is really simple to understand. You have a nucleus, which has charge and spin. It therefore acts like a little bar magnet aligned along the spin axis. Similarly, the electron has a charge and spin. It also then has a magnetic field. These two magnetic dipole moments are in a lower energy state... | [
"Hey there, I worked for NIST for a while (though not in the Time and Frequency division). They're the people that build and maintain the standard atomic clock(s).",
"It's just a choice of convenience really.",
"It's more than ",
" convenience. You can define the second in a ton of different ways. All you nee... | [
"The frequency of the photon it emits is how many times it oscillates per unit time. If you define that unit time as ~1/86400 of Earth's rotation, then the frequency is 9.2 billion whatever times per second. If you make the second longer then the frequency is higher.",
"Given that a Hz is 1 per second, you can sa... |
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