title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Is there a place on earth where meteors hit fairly regularly?"
] | [
false
] | Is there a place on earth where meteors hit fairly regularly? I know we get approximately 17 meteors hitting the earth a day but I want to know if anyone would know if there’s a place that they commonly hit. | [
"There are places where meteor strikes are more and less apparent- Antarctica, with its lack of vegetation and snowy ground cover is near ideal for spotting meteorites. The ocean basins are places where they are least apparent, due to the lack of ability to closely observe much of the bottom and the nature of the w... | [
"The simplest answer is no, they are random."
] | [
"Correct, they are random. So the place that gets hit the most is the Pacific Ocean, simply because it's the largest place on Earth."
] |
[
"Why does video shown at 50-60fps look so unnatural?"
] | [
false
] | null | [
"Are you talking about \"High Frame Rate Movies\", or just anything at 60 fps? A game, for example, shouldn't look unnatural, it should usually look more natural at 60 frames per second than something like 30, but motion in a game is going to be generated differently.",
"Movies might look unnatural, and at a high... | [
"It's just because you are used to 24fps video."
] | [
"First, let me point out that I am not vision, video or TV expert...",
"Are you asking when does a frame rate become unnecessarily high? Well, there are technologies that go as high as 300 fps... Those would probably get scaled down to be viewed. So it's difficult to say what is unnecessary.",
"(Looking up the ... |
[
"Is it true every atom in our bodies came from a star that exploded?"
] | [
false
] | null | [
"Except some hydrogen, helium ",
" atoms , whom have existed since the Big Bang, all elements comes from dead stars, since it's the only place, where it is hot and dense enough, for larger atoms to form.",
"Edit: Thanks ",
" and ",
" for letting me know about the lithium."
] | [
"Not a silly question, when a supernova scattered the heavier elements through the galaxy the shockwave runs into pre-existing clouds of hydrogen/helium. This disturbance can cause the cloud to begin to collapse, forming a star. It is ",
" sensible that this could have happened with our star meaning a lot of the ... | [
"Is it likely that these hydrogen and helium atoms have all gone though a star? (this feels like a silly question)"
] |
[
"Would gravity be possible as we have it on Earth on a flat surface?"
] | [
false
] | As I understand gravity, objects are drawn towards the center of mass of an object. Since Earth is relatively spherical, the center of mass is in the center of mass is in the center, and gravity works like . (with the red square being the center of mass, the red arrows being the direction of gravity, and the green dot being the Earth) On a flat surface (like previously thought by many who-knows-when), gravity would work like , where people near the outer edges of the surface would essentially be standing on walls. Is gravity like shown in the sphere possible on a flat surface? | [
"On a flat infinite surface, the gravitational field is constant and pointing in the direction of the surface. "
] | [
"You're beginning with an incorrect assumption. Gravity doesn't attract towards the center of mass. What happens, though, is that a spherical body of even mass distribution acts (mathematically) like a point mass when you calculate its gravitational field. In other words, the \"center of mass\" assumption convenien... | [
"This problem is mostly worked out in terms of electric fields rather than gravitational, but they behave the same. You can treat a capacitor as an infinite surface with constant charge density, and use either Coulomb's or Gauss' law to figure out that the electric field is constant."
] |
[
"Do bugs sleep? Plain and simple."
] | [
false
] | Do bugs sleep? (insects, spiders, moths,flies, the colloquial application of the word bugs is implied) | [
"Yes. The only living organisms that ",
" sleep (in some form) are the ones who don't live long enough to incorporate the day/night cycle into their lifespans, ",
". Plants sleep. Slime molds sleep. Single-celled organisms sleep. The common misconception that \"sharks don't sleep\" comes from the observation th... | [
"Mayflies live for a significant amount of time as nymphs. Would they not sleep during that period?"
] | [
"Also sleep is not always linked with the day/night cycle. Apparently ants sleep about 200 times a day. For one minute each time."
] |
[
"Why is the Prandtl number for the Earth's mantle so high?"
] | [
false
] | On Wikipedia's entry for the , it states that the earth's mantle's Pr is around 10 . Does plate tectonic activity contribute to a high kinetic viscosity (∴ high viscous diffusivity) relative to a very low thermal diffusivity, or is the latter just extremely low relative to a low viscous diffusivity? | [
"It's not actually correct to describe the mantle as magma because it's not predominantly melt. In fact there's practically no melt there at all. It's crystalline but able to plastically deform. "
] | [
"This is really because magma has an incredibly large viscosity.",
"It's pretty common to picture magma in the mantle as similar to liquid lava pouring out of a volcano, but the material properties are ",
" different. For all intents and purposes, if you had a piece of magma sitting on your kitchen table, you'd... | [
"Right, this is true - I probably should have just said \"mantle material\". It's also important to point out that those deformation rates are much, ",
" slower than a lot of folks think.",
"On average, a piece of the mantle is going to move about one inch per year."
] |
[
"What is the chemical progress that happens when you freeze something and then shatter it?"
] | [
false
] | I assume it has something to do with the atoms, but I might be wrong. | [
"Objects smash when you freeze them because the water inside them turns to ice, and ice is very brittle. This liquid to solid phase transition is a physical change rather than a chemical one, so the chemical structure of your arbitrary object remains essentially the same. There are very likely a large number of wea... | [
"also if the OP is talking about the freezing flower (apple, broccoli, etc.) in liquid nitrogen; rapid freezing ruptures cell walls, so even if you let it melt instead of shattering it you'd be left with something that's more like broccoli soup than the original broccoli."
] | [
"This is a difficult question to answer as phrased. Matter can exist in 4 phases, solid, liquid, gas, and plasma. \"Freezing\" something colloquially involves a conversion from its liquid state into a solid one. Not all solids are brittle, and therefore don't shatter (think of steel, or rubber for example). ",
"W... |
[
"Gene-swapping vaccines spawn lethal poultry virus - Could this happen with human vaccines?"
] | [
false
] | [deleted] | [
"It's possible, but we are much more careful about vaccines we use in humans. First off, majority of human vaccines these days are not full, live, attenuated viruses as was the case in these chickens. Instead they are specific epitopes (i..e. a small part of the virus that acts as a recognition sequence for the i... | [
"Yes, Polio itself or vaccine associated paralytic poliomyelitis (VAPP) can be caused by vaccine derived poliovirus (VDPV) from OPV (live attenuated oral polio vaccine). ",
"Either there is reversion to wild-type by mutation, divergence of vaccine strain into two distinct strains which recombine ('gene swap'), or... | [
"[–]Surf_ScienceGenetics|Systems Biology|",
"I'm guessing that would be Yellow Fever. Maybe Polio is runner-up?"
] |
[
"When you leave a carbonated drink to sit for a while after being shaken to avoid it fizzing over, what is actually happening here?"
] | [
false
] | null | [
"A carbonated drink means theres dissolved co2 in the liquid. The concentration of dissolved co2 depends on several factors but the main one in this case is the co2 concentration in the air above the liquid's surface. If you've noticed, all carbonated drink bottles are somewhat pressurised, even if they havent been... | [
"The paper I cited shows that pressure actually ",
"drops",
" (marginally) upon shaking. I haven't observed that a shaken bottle is more difficult to compress.",
"\nBasically what's happening is that shaking introduces more nucleation sites for CO2(g), allowing CO2 to form nanosized bubbles. Bubble formation ... | [
"Thanks for the mention. The slight pressure drop makes sense to me: the equilibrium between gas and dissolved species depends on having a ",
" gas/liquid interface, so a gas molecule at the interface is just as likely to enter the liquid as the gas. If the surface is a curved bubble, there's slightly more liqui... |
[
"Can the gut microbiome restore itself to healthy levels after antibiotics and if so, how long does this take?"
] | [
false
] | null | [
"PhD in Gut Microbiome here - yes they can restore - as for time it’s very dependent on the situation pre abx exposure- infants with a naive microbiome can take years to return to a pre-antibiotic treated state. \nAlso of course you’ll have opportunistic pathogens trying to gain detrimental colonisation. Someone sa... | [
"In general - if you just check the box/bottle and if there’s some Bifidobacterium that’s always a good sign - they’re a great commensal - strains of bif longum and bif infantis, bif bifidum have been shown to be positive probiotics for various issues - specifically good for infants. Lactobacillus also another grea... | [
"What are some properly researched and licensed strains please?"
] |
[
"Why does intense pain make me nauseous?"
] | [
false
] | null | [
"I suspect a few possibilities. For one, injury causes not only pain but also activates the sympathetic nervous system. This is a protective response to minimize damage while also keeping you alert because injury makes you incredibly vulnerable in the wild. Sympathetic activation decreases blood flow to the skin in... | [
"Wow, thank you for such an indepth answer. I remember feeling so sick to my stomach and I was focusing instead on not throwing up that I forgot the pain for a bit.",
"I appreciate your time in answering!"
] | [
"Thanks! I study pain for a living, so whenever I see a question I can give a decent explanation for I try to do it. "
] |
[
"Do cells have specific sizes or can they be incredibly large or incredibly small?"
] | [
false
] | As an adult I've discovered an interest in the AP bio classes I largely and regretfully ignored. So I'm learning from scratch now how my body works. I just watched a video about T cells, viruses, and b cells and it seems like they all come in different shapes and sizes. What are the similarities that make a cell a cell? Can they be as small as, say mRNA or a protein? Why isn't a protein a cell? Thanks for your patience. | [
"Great questions and welcome back to biology!! ",
"A cell is defined by its boundaries. Each cell is an individually competent unit of life, I.e it carries out the functions it needs to survive within itself (intracellularly) or gets what it needs from its environment (extracellularly). Human cells, as well as al... | [
"Upper limit is set by surface area to volume ratio. Volume increases by cubes, but surface area by square so you start hitting limits of transport and diffusion. Lower limits are reached because there just us to be enough room to get things done. Some bacteria are probably near the lower limit."
] | [
"That is true for all 3 dimensional shapes, not only bacteria. ",
"It is cause by geometry and not anything biological."
] |
[
"Why is it no matter how hard you blow underwater there are bubbles and not one big bubble?"
] | [
false
] | I was swimming and just wondered. No matter how hard I blew, a bunch of bubbles came out. I was underwater on my back, same thing. Why is it that you have a bunch of bubbles as opposed to a long bubble, like a balloon then? Stupid question, maybe, but thought I'd ask. | [
"It's not a stupid question at all. I thought about this question for about 10 minutes now and could not think of a reason that I feel at all comfortable posting! Great question."
] | [
"The behavior of water, or any substance, at temperatures below every day experience and at varying pressures is difficult, if not impossible to describe in words. There are many interesting predictable effects at low T and many more that are yet unexplained. It's an exciting field!",
"tl:dr - I have no idea. ... | [
"what if we were swimming in really low temperature water under absurd pressure to keep it from freezing?!"
] |
[
"Are humans red or white meat?"
] | [
false
] | null | [
"I seriously doubt we differ so much that our muscle fibres would be another class. "
] | [
"Red meat. White meat is reserved for fast twitch muscle like fish, which we have little of (maybe black people have more white meat)."
] | [
"That's racist!"
] |
[
"Where did the electricity for telegraphs come from during the American Civil War?"
] | [
false
] | Looking at Wikipedia, it mentions electromagnets and voltaic piles, but I don’t understand how such a small amount of electricity would be able to travel the hundreds of miles needed. I can notice a reduction of power in my leaf-blower when using multiple extension cords, so how would wires from the mid 1800s be able to carry a signal from an early electrochemical battery over a meaningful distance? Edit: Thanks for the explanations and analogies, they’ve really helped! It makes a bit more sense now. | [
"In addition to the other answers: they ",
" have ",
"repeaters",
". But, these were not like modern repeaters -- they were human beings. The human operator would hear the (weak) signal coming in and, by hand, send it on down the line, now at full strength again. ",
"At some point this was automated but I ... | [
"They also had electromechanical repeaters from around 1840ish. It makes sense, considering that telegraph sounders basically WERE relays to begin with."
] | [
"The signal in early Morse telegraphy was very simple -- \"voltage on\" or \"voltage off\".",
"As long as there was enough voltage left at the receiving end to activate an electromagnet (creating the clicks, or marks on paper, etc.) the message could be copied. With enough voltage in the system and sufficiently t... |
[
"What makes a tumor inoperable?"
] | [
false
] | [deleted] | [
"Location, location, location. In ",
" general, it's because the tumor cannot be cut out entirely. Remember that even a single cancer cell can bring about a whole new tumor, so surgeons must be very sure they can get it all or else they cannot cure surgically. Another reason is that if the tumor has already sprea... | [
"To add to this, physicians also take into account the specifics of a person's history to determine if it's worth operating on. It's all about cost vs. benefit. If you have an 90 year old man with a pancreatic tumor, the risks associated with getting to it, or even operating and anesthesia for that matter, are almo... | [
"Almost every tumour is \"operable\". In the least the surgeon can do a debulking procedure, that is, cut out a chunk of the tumour to reduce the size, the idea being that a smaller tumour is more tolerable to the patient, and there are other palliative (and non-curative) surgeries that can be done to improve quali... |
[
"Why do large animals with bigger hearts have a lower resting heart rate compared to tiny animals who with smaller bodies and thus smaller hearts who have much higher resting heart rates? (Think whale vs mouse)"
] | [
false
] | I am curious as to why small animals, such as the mouse I found in my kitchen, with it's tiny body and small amount of blood to pump around, has such a high resting heart rate, even if it's just sitting there doing nothing. By comparison, a whale or elephant, with their massive hearts in proportion to their massive bodies, have a much lower resting heart rate, yet have so much more liquid to pump around.Is it just that as the heart gets physically larger it also gets stronger out of proportion to it's size e.g increase size tenfold it gets a hundred times stronger, thus less heartbeats required? | [
"Total metabolic rate ",
" with body size. Metabolic rate per unit of mass generally decreases as the surface area to volume ratio decreases. ",
"An elephant burns more kcals per hour than a mouse because there is much more cellular activity in the elephant than the mouse because there are many, many more cells... | [
"I remember reading that because small animals are small they have high metabolic rates. They need more energy to keep maintain their temperature. So with a higher metabolic rate the cells need more fuel, therefore more heartbeats to transport the fuel via the blood. Also what the other guy said probably has someth... | [
"I've been trying to find an answer to this all day, and the body temperature explanation has come up a few times, but doesn't explain why the same relationship (metabolic rate increases with increasing body size) holds true for all other taxa from bacteria to reptiles ",
"(Image)",
"If anyone can elaborate fur... |
[
"Why do I unconsciously emulate the accent of those around me?"
] | [
false
] | I have to constantly remind myself not to adopt the speech patterns of people I'm holding a conversation with, particularly accents. Am I just some kind of jerk, or is there an explanation for this? | [
"This phenomenon is known as \"phonetic convergence\" within linguistics. While there are ton of studies discussing the phenomenon, (it seems to me as though the exact reason \"why\" is still uncertain) I thought this study was the most useful in answering your question: ",
"Phonetic convergence in spontaneous c... | [
"Please everyone: This is not asking if you do the same thing, it's asking for an explanation. Please no more \"me too\" posts. "
] | [
"http://en.wikipedia.org/wiki/Style_shifting",
"It's more prevalent in Asia with tonal languages, and at least in Malaysia where people speak 2/3 languages, multiple dialects and accents, it's considered necessary to change your speech patterns unless you don't look like a local."
] |
[
"Are there invasive species that benefit the local ecosystem?"
] | [
false
] | null | [
"Yes! In varying degrees, of course. ",
"First, there are invasive species that fix what human activity (including the introduction of other, destructive invasive species) already disrupted.",
"It provides habitat for young invertebrates and fish in places like the southeastern United States",
"re-populating ... | [
"Usually a species becomes invasive because it has no real predators and fills a gap in an ecosystem more effectively than the native species, whether that be plant or animal.",
"Most of the time they become destructive by out competing rival species and exhausting prey species."
] | [
" the Western honey bee. Its native to Europe/Africa/Asia not the Americas or Australia and was introduced to the Americas in the 1600s and later to Australia. It quickly spread across all the continents and by modern standards would be considered invasive as it likely out competed native bee species. However the s... |
[
"Introducing /r/AskElectronics: a new subreddit along the lines of this one, for all your circuits/electronics questions"
] | [
false
] | All technical questions are welcome, at any level of expertise. | [
"Do you honestly think that ",
"/r/askscience",
" wants questions like:",
"Do I need a GFCI in this circuit?",
"How does one calculate the power gain as well as power dissipated through a transistor?",
"what is the symbol to represent a boost converter in a circuit diagram? ",
"Looking for a good VCO IC... | [
"Do you honestly think that ",
"/r/askscience",
" wants questions like:",
"Do I need a GFCI in this circuit?",
"How does one calculate the power gain as well as power dissipated through a transistor?",
"what is the symbol to represent a boost converter in a circuit diagram? ",
"Looking for a good VCO IC... | [
"StackOverflow is probably better, but ",
"here you go",
"."
] |
[
"Using another liquid for steam-powered engines?"
] | [
false
] | This post is inspired by this image: My question is: would it be feasible to collect the water vapor and use it to heat another liquid with a lower boiling point? Would this increase the efficiency of a steam-powered engine, or would heat loss/something else be too great a barrier? | [
"Yes you can use other working fluids. IIRC pentane is sometimes used in geothermal power plants.",
"Lower boiling point means lower thermodynamic efficiency for rankine cycle engines.",
"http://www.douglas-self.com/MUSEUM/POWER/oddfluid/oddfluid.htm"
] | [
"No materials lose mass when converting to steam. Perhaps you're thinking about density? Mass is always conserved.",
"You can compress any vapor back into a liquid, but doing so requires that you put back in all the energy you got out, so it doesn't benefit you."
] | [
"Compound Steam Engines",
" featuring multiple expansion stages were very popular precisely because of the potential to increase efficiency. Extending the concept further with the use of another working fluid is technically plausible, but the gains that could be realized are generally not worth the extra complex... |
[
"How does smoke function in a zero-g environment?"
] | [
false
] | null | [
"We are used to seeing smoke rise up, because it is carried by convection currents. In microgravity, there would still be air currents but no set direction for the smoke to go. If the air is very still it might make a spherical cloud around the source, just like ",
"flames on the ISS",
"."
] | [
"It'd behave a lot like any other fluid that has been in a 0 gravity envirionment. It would simply move in the direction that force has been applied to it or remain motionless if no force has been applied. With no gravity present no bouyant forces are exerted on the smoke from the surrounding fluid (ie. no sinking... | [
"I'm wondering if a zero-G, still-air environment would cause a fire to smother itself out fairly easy. Without convection to expel waste gases and bring in oxygen, a fire would have to physically spread in order to get fresh oxygen.",
"At the same time, they would retain all heat generated to facilitate burning ... |
[
"How do seeds know not to germinate when inside a piece of fruit? Like a tomato or pineapple?"
] | [
false
] | [deleted] | [
"I skimmed the Wikipedia article ",
"http://en.m.wikipedia.org/wiki/Germination",
"Oxygen, light, and other factors present in the outside environment, but not present inside the fruit, all contribute to the chances a seed will germinate.",
"In your example of the pineapple seed you said no light was required... | [
"If you just bury a tomato, a cherry tomato in particular, or even leave it on the ground it will germinate next season, so it doesn't have to out of the fruit.",
"Some fruit won't germinate until after the fruit has gone through an animal's digestive tract. In Australia there are seeds that won't or can't germi... | [
"I have a soil mix that has old tomato seeds in it. These seeds only germinate and sprout when they get close enough to the surface, like when I've just filled a new pot. In a clear container with no lid, no seeds germinated, but in pots suddenly they started growing.",
"Some seeds, like lettuce, will use specifi... |
[
"Is fat burned during or after exercise?"
] | [
false
] | I know excersizing burns fat, but does it occur while you're excersizing or does it take place afterwards? | [
"Both. Mostly during heavy breathing exercising like cardio. Keep in mind that most of your fat is actually breathed out. When fat is burned it converts to about 20 percent water and 80 percent CO2 which you then breathe out. "
] | [
"The simplest answer, both. But the time that your body burns the most fat is after exercise. This is because fat loss has a lot to do with your metabolism. During exercise, your body uses carbohydrates as energy to fuel your body's movements. When your body is depleted of carbohydrates, your body switches to fat t... | [
"http://andrewskurka.com/2015/metabolic-efficiency-test-results-hiking-running/",
"The above blog post gives the results of hiker and ultrarunner Andrew Skurka's ratios of fat and carbohydrate burned at a range of paces."
] |
[
"Does bacteria become resistant to dish soap?"
] | [
false
] | Dish soap and similar products always claim that they kill 99% of bacteria. If we have antibiotic-resistant bacteria, why don't we get dish soap-resistant bacteria? | [
"I'm a little puzzled by gfpumpkins comment, as a) I can't find any dishwashing liquids that use triclosan (hand soaps, yes, but not any dish soaps. Disinfectants appear to be more common in dish soap), and b) studies have found little evidence that bacteria can become resistant to triclosan (",
"source",
"). "... | [
"Does dish soap have a similar effect on skin? If not what is the difference between skin and bacteria?"
] | [
"Does dish soap have a similar effect on skin? If not what is the difference between skin and bacteria?"
] |
[
"If you had ALL the data from seconds after the big bang, knew all the laws that dictate time and space, and were able to process it, could you predict the entire history of the universe?"
] | [
false
] | I know that the few moments after the big bang were essentially chaos, but chaos as I understand it just means too many tiny variables to ever accurately calculate. If you knew where every bit of matter/antimatter in the universe was, it's speed and mass and energy, and knew all the laws of nature, including things like what goes on inside a black hole, couldn't you extrapolate that out to predict the entire history of the universe if you had some insanely powerful supercomputer? I suppose this question gets at free will as well, could you predict human events and even thoughts? Am I destined to be sitting here on reddit at this exact time typing this exact question? Is anything truly random? | [
"That's a very interesting question, and I thought about it a lot.\nAssuming there is no God or other influence, the answer would be that that we can't predict what is going to happen with great accuracy.\nNot every process in nature is deterministic. For example, radioactive decay is not deterministic (you don't k... | [
"This is more a philosophical than a scientific question. The Universe contains irreducible (chaotic) systems, such as turbulent eddies, brains, and, well, computers simulating discrete irreducible problems. Such systems are not subject to modeling under any approximation, because small errors between the actual ... | [
"If the current understanding of quantum mechanics is accurate, then it is impossible to know those things, regardless of technological advancements. Read this: ",
"http://en.wikipedia.org/wiki/Hidden_variable_theory"
] |
[
"What is the evolutionary reason(s) behind dogs having dichromatic vision?"
] | [
false
] | I've always wondered about this. Dogs can see violet/blue, yellow, and shades of grey. Why? Blue isn't common in nature and yellow doesn't seem that important. Wouldn't red/green be a lot more beneficial for a dog? | [
"all mammals except for \"old world\" primates have dichromatic vision (or even less - i think that cetaceans only have a single cone pigment - can't look it up now but I think they lost the short-wavelength pigment long ago).",
"primates developed a mutation that produces a variation on the longer-wavelength con... | [
"True but I think these are very very minor differences, getting that extra ability to distinguish spectral differences apparently more than makes up for the very slight loss in sensitivity.",
"In our case, the L and M cones have such overlapping spectra that they ",
" encode the same light - but it's the diffe... | [
"there's virtually no cost to implementing it.",
"Wouldn't they be losing sensitivity at their original range of frequencies if they had replace some of their receptors with the new '3rd color' receptors? ",
"Similar to how we humans have better overall light sensitivity at the pheriphery of our eyes than at it... |
[
"What is mass? What do scientists mean when they say a particle has no mass?"
] | [
false
] | null | [
"Mass is what makes objects resist changes in velocity. Particles without mass always go at the fastest possible velocity."
] | [
"Mass is what makes objects resist changes in velocity.",
"For some reason that sort of opened my eyes, mass is just simply the property that resists changes in velocity. Thats it."
] | [
"Neutrinos may be commonly treated as massless where it is convenient, but it is not believed that they are actually massless. Like quarks and electrons, neutrinos come in three varieties of different mass. The only way they can have three different masses is if their mass is not 0."
] |
[
"Is There a 100% Reflective Surface?"
] | [
false
] | Mirrors don't reflect 100% light. Is there any surface that does? I think it'd be impossible for such a thing to exist though. Prove me wrong! (or not) | [
"It is of course impossible to get 100%, but you can get pretty good. There are superconducting microwave cavities that are used in particle accelerators and/or quantum experiments with quality factors approaching the billions. Basically two mirrors facing each other; inject a photon and it bounces off each mirro... | [
"TIR is a perfect 100% reflection, but it requires going through a medium that has some absorption."
] | [
"The photons would need to be scattered for you to see it was actually on. "
] |
[
"Why are is blood delivered so slowly during a transfusion?"
] | [
false
] | 200 ml/hr seems ridiculously slow. | [
"I agree that a slower infusion might limit harm from a transfusion reaction. ",
"The second part of your answer is incorrect though. As blood is (by definition) isotonic, giving a single blood transfusion slowly is very unlikely to cause changes to plasma osmolarity and gross fluid shifts (unlike unbalanced crys... | [
"I agree that a slower infusion might limit harm from a transfusion reaction. ",
"The second part of your answer is incorrect though. As blood is (by definition) isotonic, giving a single blood transfusion slowly is very unlikely to cause changes to plasma osmolarity and gross fluid shifts (unlike unbalanced crys... | [
"So RBC are concentrated and hypertonic during the transfusion",
"No! This is also flat out wrong. PRBC are isotonic. The cells are separated out physically, by centrifuge, but that doesn't change the tonicity of the fluid they're suspended in."
] |
[
"How do Parallel SEM Avoid Interference Between Parallel Electron Beams?"
] | [
false
] | Today I learned that companies like Zeiss have electron microscopes that have parallel electron beams, to increase scanning rate. However, given that electrons are negatively charged, how/why do the parallel electrons path's not become distorted? Do computers do the math to correct for distortion caused by electrostatic repulsion? | [
"You could look up beam currents, typical separation of the beams and calculate the effect size based on that, but there is a much simpler approach: Compare it to the effect of the beam on itself. The electrons in a beam repel each other. They are ",
" closer together so their repulsion is much stronger. That is ... | [
"The statement is true for any beam currents, the self-interaction will always be stronger. ",
"This paper",
" discusses how stronger beam currents can lead to notable electron-electron interactions within a beam."
] | [
"Aren't beam currents In a SEM sufficiently small that the electrons don't interfere with each other? At least that's what I remember being taught. Should be easy to calculate given the current, velocity and travel distance are known"
] |
[
"If we found a meteorite on Earth that originated outside the solar system, how would we be able to determine its age?"
] | [
false
] | null | [
"With every applicable method that can be used for meteorites in our solar system within a margin of error. The application of a dating technique is not limited by the origin of the object but by its history, mineral and therefore element content, etc. If I take a basalt from Earth or from Marsfor example, I can st... | [
"if we assume similar partition coefficients (and why should they be different in another place of the universe?)",
"They wouldn't, but the absolute abundances of the elements do vary widely across the galaxy. I would have thought that makes it harder to translate an isotope ratio to an age."
] | [
"This is true, but this comes mostly down to measurement accuracy then. The methods themselves would not differ, only perhaps the instruments used would differ. So instead of e.g. an ICP-MS (I know, not commonly used in dating) you would use...the frick do I know; maybe an AMS?"
] |
[
"Why did humans evolve to be mostly hairless?"
] | [
false
] | Seeing as humans evolved on the plains of Africa, where most other examples i can think of animals living in that habitat have fur. What benefit did losing most of our hair (or at least it's becoming so fine that we are effectively hairless) have for our species? | [
"Sweat.",
"Relevant TED. (Important part starts at 5:00. Answer is at 9:30)",
"Humans are weak. We aren't fast, we aren't strong, we can't camouflage, and we don't have claws of big teeth. But we can run forever. Which led to an interesting method of hunting. Persistence hunting, where you chase one animal unti... | [
"It could be simply a mutation that ",
" beneficial, but propagated anyhow. People need to realize that evolution isn't always about ",
" - it's about a mutation that carried on through a successful ancestry. ",
"As an example, a three horned goat with fingers might propagate because it has fingers, but ... | [
"how about why humans have hair in their armpits and groin, yet other apes have the opposite. Related but just as strange. "
] |
[
"If one had an infinite amount of carbon and hydrogen, and let them react, which hydrocarbon would be formed?"
] | [
false
] | There are an incredible amount of different hydrocarbons that exist. A lot of these hydrocarbons are more stable than elemental carbon and hydrogen, which means that if carbon and hydrogen are put together, a reaction would occur. How is it "decided" which one is formed? | [
"What makes you think a single molecular species would be formed?"
] | [
"under what pressures and temperatures? If you're at absolute zero, nothing will happen. You need to define boundary conditions for this question. "
] | [
"Infinite amount of what graphite? double bonds? Organic reactions (or most for that matter) aren't as simple as putting two elements together/ Saying an infinite amount of carbon and hydrogen is like asking how fast you could go with an infinite amount of fuel and wheels"
] |
[
"[Chemistry] If Hydrogen bonds to Chlorine, is there any way this can be ionic?"
] | [
false
] | I know HCl is covalently bonded but is there the possibility it can be ionically bonded? | [
"Every bond can be described as having some degree of covalent and ionic character. That 1.7 difference in electronegativity cutoff is just something we tell freshman students because they need something to memorize and regurgitate on exams. The greater the difference in electronegativity, the greater the percent... | [
"As an aside, bare protons are too unstable to exist in aqueous solutions. A \"hydrogen ion\" is actually a hydronium ion, or H3O+"
] | [
"Upvote for more complete answer. But I don't think anyone would call HCl ionic. "
] |
[
"Dating amber and the fossils within. How do they do it?"
] | [
false
] | ... because you see these fantastic fossils congealed in amber, but since amber is a thing that oscillates between solid and liquid, and since carbon-dating is more complicated for really old stuff ... and so on and so forth, I just got this hunch that when they say this lizard is 65million years old, it seems just remotely possible that sometimes they might be far far off. How is it done? Example stupid situation: some tree sap drips into a little rock pocket that is kept freekishly warm for eons because hey, why not ... and a lizard creeps in last thursday (give or take a few decades) and suddenly the environment of the ambr changes and it solidifies. That afternoon it is spotted and transported with great enthusiasm to a place that estimates the surrounding rocks as being multimillions of years old. But that lizard knew a world with wifi. Hyperbolic, I know, but it's to make my doubts easier to understand. | [
"Dating Amber is complicated, as you must use an indirect approach (… aaaaaand, in just one sentence, here I am in ",
"/r/outofcontext",
" territory…).",
"So … Amber, it’s complicated…",
"Amber is a carbon-based compound, the only radio-elements it contains which might be usable are carbon isotopes … and C... | [
"Another lovely answer. Thank you very much. Is it fair to say, going by your last paragraph example, that in the case of a lizard in some amber, and latching on to the \"only determines a maximum age\" thing, it is difficult to affirm that the lizard got stuck in the Amber at the same time that the volcanic pebble... | [
"on to the \"only determines a maximum age\" thing, it is difficult to affirm that the lizard got stuck in the Amber at the same time that the volcanic pebbles got stuck there",
"That's not quite the nature of the problem - there is no doubt the lizard and pebbles (if there are pebbles with the gecko - I do not k... |
[
"Using spectrophotometry to estimate biomass?"
] | [
false
] | I was doing some work in a lab over the summer, including recording in vivo (blue) chlorophyll of some plankton samples. I've recently been sent the data (I'd given it to a lab technician to put into excel), and 'chl in vivo blue' is recorded in fluorescence (RPU). What is this unit? And is there a way I can use this to estimate biomass? Other data I have are abundances and biovolumes, but without cell density, I don't know how I can calculate biomass. Does anyone have any suggestions? | [
"Fluorescence is often measured in arbitrary units, I've always seen them called \"RFU\" or relative fluorescence units. You need a standard curve of known concentrations of plankton in order to convert the fluorescence into a cell density or biomass sort of measurement."
] | [
"I have these ",
"growth curves",
". ",
"I also have the corresponding fluorescences, so could I combine these to create a biomass curve?"
] | [
"Yes, if you have the fluorescence values for a bunch of known concentrations of cells, then you can graph them against each other (that is, graph RPU on the x-axis and the corresponding cell densities on the y-axis) and use excel to generate an equation like y = mx + b, where x is the RPU and y is the correspondin... |
[
"Why are potato chip bags made with aluminum? What special property does it have that makes it preferable to 100% plastic?"
] | [
false
] | Bonus question: If the bag is made with aluminum, how come you can see light through the bag? | [
"Because metallized films are more expensive, and if the product isn't sensitive to oxygen it's not an economical choice to use them. Packaged ready-to-eat cereals are usually low in their unsaturated oil content and so rancidity isn't an issue with them. Plastic films do a good job of providing a moisture barrier,... | [
"The metal content of the film provides a superior barrier to oxygen over pure plastic; which allows the product to maintain quality longer."
] | [
"It's known as Modified Atmosphere Packaging, and it shows up in other places as well. In oxygen-sensitive foods (potato chips are a great example, as the oil content makes them susceptible to rancidity) the in-package atmosphere usually decreases the oxygen and increases the nitrogen content. For fresh vegetable p... |
[
"Why some people passed out when they saw Michael Jackson and some don't?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"/r/AskScience",
"For more information regarding this and similar issues, please see our ",
"guidelines.",
"If you disagree with this decision, please send a ",
"message to the moderators."
] | [
"Where do I ask then? I seriously searched everywhere I could and I can't sleep properly. Can you send me on track? Help is much appreciated."
] | [
"Not quite sure to be honest."
] |
[
"Do other mammals get headaches too?"
] | [
false
] | I’m specifically wondering about dogs, but do all mammals get headaches? If so, how can we tell that they have a headache? Do they also get migraines? | [
"Glaucoma (increased intraocular pressure) can cause something akin to a migraine in dogs due to the acute increase in pressure on the optic nerve. If the retina is already non-visual and enucleation (surgical removal of the globe) is performed, you can see near immediate relief in some dogs based on their demeanor... | [
"I've heard about elephants getting something called Musth which causes them to become highly aggressive. The temporal glands swell up and press on the elephant's eyes and cause pain. It's believed to be comparable to a severe root abscess toothache. It could be similar to, or cause, a headache.",
"https://en.upa... | [
"There was a 2013 paper published about a dog with migraines.",
"The dog in the 2013 study occasionally experienced episodes of apparent fear, which were followed by the dog emitting vocalizations. These episodes were observed throughout the dog’s life, beginning when she was about 6 months of age.",
"The episo... |
[
"Could a nut and a bolt made of perfectly rigid materials be tightened together?"
] | [
false
] | Lets say we have mathematically perfect, rigid material and you make a nut and a bolt out of it - could the two be tightened together? Im asking because I noticed that good quality nuts and bolts screw into each other with little to no resistance and only become tight once maxed out - what exactly happens at the last bit and why it gets tight? Im assuming the materials get ever so slightly bent, deformed and thats what makes it tight? | [
"I’ll give it a shot. The screw doesnt become tight before maxing out since all the grooves slide against each other. When the screw is completely in, the sliding is no longer possible and further twisting will press the surfaces tight against each other and the friction holds it in place. In practice some elastic ... | [
"further twisting will press the surfaces tight against each other and the friction holds it in place",
"With nonsticky materials, friction arises predominantly from deformation of surface asperities. This wouldn’t happen with perfectly rigid materials. It would be like sliding wet ice on wet ice; the nut would l... | [
"We can look at it the other way: such a nut&bolt would tighten but infinitesimal amount of force would open it."
] |
[
"If something is 41degF hotter than another thing, is the difference 5degC or 23degC?"
] | [
false
] | null | [
"The conversion from F to C is",
"F = (9/5)*C + 32\n",
"so any difference in F, F2-F1, can be written",
"F2-F1 = (9/5)*C2 + 32 - ((9/5)*C1 + 32)\nF2-F1 = (9/5)*C2 - (9/5)*C1\nF2-F1 = (9/5)*(C2-C1)\n",
"So if the difference in temperature is 41 F then the C equivalent is ~22.8C"
] | [
"Thanks. The internet here is really slow and I have a hangover. ",
"I don't know how linear the scales are.. but I arrived at 22.77...9C with: (100/180)*degF\n..those numbers being the change in degrees from freezing to boiling in each scale."
] | [
"I'm not sure what you mean by from freezing to boiling. ",
"In C the difference is 100C (0 to 100), which translates to (9*100/5) = 180 degree difference in F (from 32 F to 212 F).",
"In the case where the temperature difference is 41F then yes, 22.77...9C is the right answer (I rounded up in my original post)... |
[
"Why do some animals lay brightly-colored eggs?"
] | [
false
] | confused me. Wouldn't brightly-colored eggs be easier for predators to see? I understand that evolution doesn't act with intention, but I'd think those animals with more naturally-camouflaged eggs would find theirs eaten less often. | [
"Great question. The short answer is we are not sure. Here is one potential explanation: Eggs need to be distiguishable, because otherwise another bird could infiltrate their own eggs into other birds's nests. Some Cuckoo birds do this (it's called brood parasitsm if you want to learn more). If all eggs were all ca... | [
"College class prof used robin's blue eggs as an example of measured directional selection. Studies (nope, don't have sources handy as class was taken years ago) found that bluer eggs were found in areas with higher incidences of brood parasites (like cowbirds or cuckoos). My fuzzy memory even says that robins were... | [
"Interesting question. I did a bit of digging and found ",
"this",
" write up which cites some research indicating that the blue color provides protection from UV radiation, which can damage embryos.",
"This ",
"article",
" cites research showing that male robins take better care of offspring from bright... |
[
"Would scientists be able to synthesize photosynthesis? If not, why not?"
] | [
false
] | I mean, could they take 6 carbon dioxide molecules and six water molecules and make glucose and oxygen? | [
"Yep. ",
"http://en.wikipedia.org/wiki/Artificial_photosynthesis"
] | [
"You're far more lenient than I am. ",
"Here's the Google search results for ",
"\"scientists make photosynthesis\"",
". You might be right basing your opinion on how OP phrased things but I won't cut an adult slack when they can't think of then word \"artificial\" ",
"The point remains that there are MDs ... | [
"When the top, only, and most concise answer is a direct link to the wikipedia page that directly answers OP's question, then yes, google your question first. ",
"Then maybe ask follow up question not covered in wikipedia. "
] |
[
"How would a scientific lab break Doritos down into its component parts?"
] | [
false
] | [deleted] | [
"You can first do a physical separation, as you proposed.",
"I think I would use a suitable solvent - or a group of suitable solvents, and blend the chips to a mush. Then one can do separation on the compounds via a number of chromatography techniques before throwing it into a mass spectrometer.",
"However, thi... | [
"As rupert1920 said your best bet would be to grind up some chips and then separate the Dorito into components that are soluble in solvents of different polarities (i.e. water soluble vs soluble in ethanol vs soluble in heptane etc).",
"Then you could use chromatography techniques like ",
"HPLC",
" or ",
"T... | [
"You can bet Pepsi has a scientific lab that's any chemist's wet dream trying to crack Coca Cola's secret. And vice versa."
] |
[
"Steven Hawking's, in In To The Universe, just claimed that 10 minutes after the big bang the cosmos was already thousands of light-years in diameter; how can this be possible?"
] | [
false
] | Obviously this is so far faster than the the traditional speed limit of 1 light-year in 1 year, I can't thing of an explination other than the show misquoted Hawking. | [
"Expansion isn't measured in speed. The distances between two galaxies may increase due to expansion at such a rate that from Galaxy A's perspective, Galaxy B recedes at a \"velocity\" greater than the speed of light, but the key here is that it's not a real velocity. Nothing is actually moving. It's just the dista... | [
"I asked a very similar question ",
"here",
". Basically the big bang was not really a central point. More like a giant plasma spanning great distances when it cooled things were already far apart from each other"
] | [
"Space-time itself is not subject to the light speed limit. Thus space-time can expand faster than the speed of light, which we see today. During early time, inflation caused massive expansive which accounts for the universe becoming thousands of light-years in diameter in 10 minutes. The observable and possibly si... |
[
"Why do some parts of the world generally experience more vivid/'better' sunsets?"
] | [
false
] | null | [
"The fluctuation in sunsets by location is to largely due to the particulate matter in the air. Since every particle has a different size, and refractive index, they cause light to refract, reflect or even diffract differently. Basically, these particles in the air, can cause light to bend/change direction and or p... | [
"And in many places the particular particulate matter (heh!) is man-made pollution."
] | [
"Although some of the prettiest sunsets I've seen have been in rural country during crop harvesting season or in desert countrysides."
] |
[
"Why does the light spectrum have bands instead of continual fading from color to the next?"
] | [
false
] | null | [
"They do fade into each other:",
"http://en.wikipedia.org/wiki/File:Linear_visible_spectrum.svg"
] | [
"Why do they appear as bands? A rainbow seem to have discrete bands"
] | [
"They fade into each other too. How's your eyesight?"
] |
[
"Why doesn't the suction power behind a fan feel as strong as the wind coming out of the front?"
] | [
false
] | null | [
"Because it's diffuse. The air coming out of the fan is in a very narrow path - the fan's energy is pointing in one direction. The air going into the fan might be coming from anywhere behind it, not from any particular angle, so the moving air is harder to feel at any one spot."
] | [
"This is how I imagine vacuum machines work. Maybe something similar but more complicated"
] | [
"So theoretically, if you put a cone on the back of a fan that was wider on the fan side and tapered down, the force of the air being sucked into the fan through that tiny opening in the cone would be greater because it is more concentrated?"
] |
[
"Do animals ever forget their own kids after a while?"
] | [
false
] | My dog just had puppies about 8 weeks ago and we are in the process of giving them away. I was wondering if the mother dog will ever recognize her children if she would ever come across them again? | [
"Agreeing with this. Dogs certainly can recognize their own family members and ",
"studies",
" have shown that reunited siblings do show kin recognition, and display behavioral differences, even after an extended absence and early separation from littermates. And while anecdotes are not science, I'd just like t... | [
"Agreeing with this. Dogs certainly can recognize their own family members and ",
"studies",
" have shown that reunited siblings do show kin recognition, and display behavioral differences, even after an extended absence and early separation from littermates. And while anecdotes are not science, I'd just like t... | [
"If this were a common practice, don't you think it would be a little bit at odds with the biological imperative to reproduce? Animals are known to eat their offspring in certain cases, but not simply as a matter of course."
] |
[
"Why can eggs/sperm be frozen for future use, but the same is not true for humans?"
] | [
false
] | [deleted] | [
"Alot of it has to do with speed of freezing/thawing. Slower freezing means big pointy ice crystals which rupture cell membranes. Faster freezing means smaller crystals. Big things freeze slower so bodies freeze more slowly and get bigger crystals. This could be overcome with really, really rapid freezing.",
"You... | [
"When you freeze an egg or a sperm, you are freezing cells that do not depend on one another for survival. Humans, however, are made of trillions of interconnected cell systems. Freezing a body would take too long and the change in temperature would not be evenly distributed. For example, if you freeze the heart be... | [
"The crux of the problem lies in not being able to freeze a complex multicellular organism instantly-at once. But also in terms of thawing, we cannot unfreeze the complex organism instantly. Instead the process occurs slowly from the outside in and then when thawing from the inside out. This of course causes major ... |
[
"Do voltaic piles lose charge over time? Why?"
] | [
false
] | My friends and I are concerned that if we were to spontaneously wind up back in time, we wouldn't know how to reconstruct modern technologies. In the interest of gaining that knowledge, we intend to make an electric motor from scratch, powering it with simple voltaic piles. In the course of our investigation, we came across the question of whether and how it is that voltaic piles lose charge. So, do voltaic piles lose charge, why do they, and how do we recharge them? Also, any other advice about whether this will work or how else we might go about this project would be much appreciated. | [
"batteries run out. You should check out why there's a current in the first place."
] | [
"A voltaic pile is based on a chemical reaction, typically where a metal reacts with hydrogen ions in an acid, resulting in a metal compound and hydrogen gas.",
"Eventually, you run out of metal or you run out of acid. Since it is not a closed system, with hydrogen escaping to the air, recharging consists of get... | [
"I am not sure what the exact reaction with the saline solution would be, but Volta's original pile was quickly improved to use an acid electrolyte.",
"The key is for the less electronegative metal to give up electrons to H+ ions and form H2. Even pure water will have H+ ions (pH 7 doesn't mean neutral, instea... |
[
"What FPS (Frames Per Second) Would real life be in? And additionally, what resolution do our Eyes see?"
] | [
false
] | null | [
"See the FAQ"
] | [
"Which section? I can't find my question under physics?"
] | [
"Neuroscience for some reason"
] |
[
"Do we know of a \"gas-moon\"?"
] | [
false
] | Is there any moon, orbiting a planet, which is made out of gas, instead of rock, that we know of? | [
"No, we haven't detected any exoplanets with moons and none of our solar systems moons are gaseous (mostly rock, one that's mostly ice/water).",
"It is also difficult to believe that such an object would be possible. The reason why the outer planets have such thick atmospheres is a result of their size. By the ti... | [
"There isn't one yet. People have suggested that Earth and the Moon are a double planet, and back in '06 people tried to make Pluto and Charon a double planet instead of Pluto being a dwarf.",
"One proposal relates to the center of mass. Right now, the center of mass (the barycenter) of the Earth-Moon system is w... | [
"we haven't detected any exoplanets with moons",
"This is \"we don't have the means to detect whether or not they have moons\" not \"we have confirmed that none of them have moons\", right?"
] |
[
"Is there a way to protect the JWST from damage from space debris or are we taking a chance that nothing will hit it?"
] | [
false
] | null | [
"There really isn’t much debris in space, especially not in places that are gravitationally unstable like where JWST is. That said, JWST is designed to withstand considerably more than the predicted amount of debris strike over its lifetime without degrading the optical performance unacceptably. Mostly it can achie... | [
"Adding to this, it has ",
"already been hit",
", but is still performing above the expected levels. There is a small be detectable signature of the strike in observations, but the data processing has been updated to account for this."
] | [
"To add a bit of trivia: The Harlan J Smith telescope in Texas (of course…) has several bullet holes in its main mirror. It still works."
] |
[
"Flying above clouds, I noticed a shadow of our helicopter on the top of a cloud, with a rainbow encircling it. What is this phenomena called, and what causes it?"
] | [
false
] | null | [
"It is called a Glory.",
"https://en.wikipedia.org/wiki/Glory_(optical_phenomenon)",
"A glory is an optical phenomenon that resembles an iconic saint's halo about the shadow of the observer's head, caused by light of the Sun or (more rarely) the Moon interacting with the tiny water droplets that make up mist or... | [
"Rainbows are caused by light refracting off water droplets when you are between the sun and said droplets. Clouds are, obviously, filled with water droplets.",
"All rainbows would like to be full-circle rainbows, but, because people are so close the horizon and rainbows take up a large field of view perpendicula... | [
"A rainbow always has the same angular size. It only depends on the index of refraction of water. Other rainbow-like optical phenomena have different mechanisms and different names, this particular example is called a glory."
] |
[
"When someone is about to die, why are they told to not fall asleep? Why does that increase survival?"
] | [
false
] | My thought is that staying awake would boost circulating catecholamines? | [
"<- EMT. Having a constantly re evaluated assessment of a persons level of consciousness (LOC) is one of the best indicators of shock. Shock is defined has the lack of perfusion in the body, in other words the exchange of carbon dioxide made in the cell that is exchanged at the capillary level for oxygen brought in... | [
"In the movies, it's for drama. In real life, it's for diagnostic purposes. A patient's level of consciousness helps us see how well their brain is oxygenated. ",
"If they can stay awake and respond to questions, that's a positive thing. If they're awake but confused and can't tell me their name or where they are... | [
"There's an indirect effect: staying awake gives more useful feedback to medical personnel about your current state, which may improve their performance and therefore give you a higher chance of living."
] |
[
"I just started learning quantum physics, and of course, I'm confused. I tried a thought experiment for determining the mass of a particle produced by a standing wave, I got that it would have imaginary mass. Is that possible?"
] | [
false
] | I asked my professor if sound waves or a waves traveling across strings have particles associated with them, and he told me they do, and they're called phonons. So I thought "why not examine a stationary arrangement of something like a string (arranged in a wave pattern - like a wave frozen in time, I suppose), and see if that produces a stationary particle?" Here is what I did: using de Broglie's equation for wavelength: lambda = (h) / (p) solving for momentum and putting it into the relativistic relation of energy, momentum, and mass [ ( E ) = ( pc ) + ( mc ) ] and setting E equal to h f (that is, planck's constant times the frequency, which would be 0) I got this relation: 0 = ( h*c/lambda ) + ( mc ) and solving for m I got the mass equal to i( ( h )/( lambda*c ) ) where i is the square root of -1. Did I make an incorrect assumption somewhere? EDIT: By the way, I know I'm wrong, I'm just wondering why I'm wrong. | [
"De Broglie frequency is defined as f = E/h so for a stationary particle (p=0) it's mc",
"/h not zero.",
"The de Broglie wavelength for a particle with no momentum is undefined since you're dividing by zero",
"Stationary particles exist in time, too, so there's no reason to stop time",
"I'm not really sure ... | [
"The de Broglie wavelength is defined how it's defined. At zero momentum it's numerically undefined (or infinite if you take dividing by zero to equal infinity.)",
"Waves oscillate. If you arrange a string in a sinusoidal pattern, but it's not moving, there is no wave."
] | [
"I'm confused. ",
"Is the de Broglie relation wavelength for a momentum-less particle wrong, then?",
"What if I have a string arranged in a wave-like pattern, giving the wave (that doesn't oscillate with time) a wavelength?",
"Then I don't think I'd be dividing by zero, would I?"
] |
[
"Chemistry Titration problem"
] | [
false
] | null | [
"OK, fair enough. I did not check your math, but what you wrote is correct.",
"I then reasoned that the number of moles used to neutralize is the same number of moles of the H+ in the acid.",
"This is true because 1 mole of NaOH reacts with 1 mole of CH",
"COOH -- they happen to react in a 1:1 mole ratio."
] | [
"Many of these acid-base problems have extra information that are irrelevant to the problem. It's just how these questions are designed."
] | [
"Try ",
"/r/homeworkhelp",
"."
] |
[
"Enzyme Question"
] | [
false
] | I have a question regarding enzymes. Asian people have a different version of alcohol-dehydrogenase which causes them to get drunker quicker. While on one hand it is true to say that they have a different version of the same enzyme. Wouldn't also be true to say that those two enzymes are technically different enzymes, although they are functionally (in terms of their purpose not effeciency) the same? That they have a different enzyme for alcohol metabolism than do caucasians? | [
"No, it wouldn't be true. Enzymes are classified by function, not sequence. It's not a different enzyme, it's a different ",
"isozyme",
"."
] | [
"So its like isotopes for enzymes?"
] | [
"I suppose it could be classified as an isotope for enzymes, but generally protein chemists use the word \"isoform\" to distinguish between two enzymes that catalyze the same reaction but they have slight variations in their amino acid sequence and their kinetic parameters. "
] |
[
"I am standing in front of an airlock in outerspace..."
] | [
false
] | Assuming my feet were bolted to the deck (so I don't get sucked out), and I had plenty of air behind me (so I never run out of air to vent), what pressure would I feel if I cycled the airlock open and closed- the pressure of the spaceship, vacuum, or something in between? Would there be enough pressure from the escaping air to allow me to survive the cycling of the airlock (like in the movies) or would I die from decompression? How about freezing to death (either temp of space or the temp of the rushing air expanding into a vacuum)? Let's assume a 60 second cycle time. Would I be able to breathe while the air is escaping, or will I end up suffocating? If the air pressure is high enough, but the air is too cold, will my lungs freeze? As for the size of the airlock door- we can go with something large enough to pass a human being through. A pinhole sized airlock doesn't count. How different will the effects be with a larger airlock, vice a smaller one? | [
"Because of ",
"Bernoulli's principle",
" the air rushing out of the airlock door will have a lower pressure than it had at rest inside the spacecraft, so you may not be able to effectively breathe when the door is open."
] | [
"I think much of this would depend on the size of the ship and how much air is stored in the ship. I am assuming the air pressure in the ship is at earth sea level of 14.696 psi. The psi around you would immediately drop and this low pressure would spread to the rest of the ship. How rapidly it would spread woul... | [
"And the closer you are to the door from the air source, the less pressure you will see. If you have a hose or a pipe, the pressure drops from the source pressure (about 45 psia for most houses) to the outlet (14.7 psia right outside the hose) So if you stand halfway down the hose, you will feel pressure halfway ... |
[
"How exactly do prion diseases work?"
] | [
false
] | i'm especially curious about Human Spongiform Encephalopathy and how it starts/spreads. | [
"Take a protein in human body. This protein has to be folded in space a specific way in order to perform its biological function, and it is folded in that way when it's synthesized by a cell.",
"If it is not folded correctly, it doesn't work and is degraded by the cell. This happens all the time in normal cells."... | [
"Does that mean you could cure a prion disease by introducing a protein that would \"re-fold\" the damaged proteins to their correct shape? A first-aid prion?"
] | [
"Theoretically, yes; I am not aware of any such having been discovered or synthesized thus far."
] |
[
"What is the smallest diameter/mass a black hole can be?"
] | [
false
] | [deleted] | [
"I don't see how that's the case. Can you elaborate?"
] | [
"Sorry, should have elaborated:",
"Planck length is the square root of Newton's constant. It's the \"coupling constant\" for gravity. When talking about micro black-holes (like the smallest you can have), there is no geometric picture, there is no notion of horizon and they behave more like bound states. Keep in ... | [
"To clear up misconception:\nPlank length is not supposed to be the smallest meaningful length. It is (supposedly) the length at which both general relativity and quantum mechanics have significant effects. The problem at this point is that we don't have an adequate theory to describe what's going on"
] |
[
"After the K-T extinction, how did the survivors live while the Earth was recovering?"
] | [
false
] | Clearly not ALL plant and animal life died out with the dinosaurs. How did the ones that clung to life in the post-Chixculub dark era do so? | [
"There's been a fair bit of back and forth about a lot of these points, but this ",
"https://onlinelibrary.wiley.com/doi/10.1111/brv.12128",
" seems to sum up the current consensus. In short: there was some loss of diversity in certain groups in the very late Cretaceous that may have made the ecosystem more fra... | [
"My question still stands. 75% of all life on Earth vanished in that perfect storm. What was life like for those that remained? How was food found in that nuclear winter? What sorts of species thrived in that environment?",
"I ask because my worldbuilding project is ",
" that sort of environment. It's been long... | [
"There is alot of myth about that impact. ",
"The thing is, dinosaurs were already on the way out. Diversity had plummeted by the late cretacious. The dekkan traps had been going off for like a million years causing major ocean acidification and climate change. ",
"The meteor was just the final straw. Pop sc... |
[
"Is there any correlation between the direction that your eyes are looking and your mood? Example: Sadness = Looking downward"
] | [
false
] | Or if you we're angry you might be staring straight ahead. Is there any relation between the two or not? | [
"Generally this type of action is done as a social que/body language, either habitually learnt from society or as to let others around us know how we feel. In the sense of sadness we will tend to try to divert from interaction with others and an easy way of doing this is avoiding eye contact by looking down or away... | [
"To elaborate on this, one might be able to categorize shifting one's gaze as an emotion regulation strategy, specifically \"attentional deployment\". Here's an example for clarification: Say you're watching a sad movie. This movie is eliciting a sad emotion from you. To downregulate or dampen this sadness you'r... | [
"Yes. Google body language and eye/gaze direction."
] |
[
"When taking a shower, whats the difference between water pressure and water velocity? Low flow shower heads don't restrict pressure, do they?"
] | [
false
] | When people say the shower doesn't have any pressure because the water isn't shooting out of the faucet, don't they mean that the shower doesn't have any velocity? Does pressure even affect the shower quality? | [
"P = v"
] | [
"In the US , a low flow head has to be below 2.5 gallons per minute and 80 psi. Some aerate the water to reduce flow. These suck. Look for non-aerating heads. "
] | [
"You ",
" can take the aerator out if it is right at the thinger where you screw it on."
] |
[
"In devices that require multiple batteries (like say, an xbox controller) do both batteries lose same amount of charge over time? What would the battery-life expectancy be if I changed only one battery, when both old ones are dead?"
] | [
false
] | null | [
"In most cases you use multiple batteries to increase the total voltage to a level needed to get the needed work out of it. So for example, if you need a voltage of 4V you can stack up four 1V batteries in your circuit. For example, that's the main reason why the orientation of battery generally alternates, ",
"... | [
"No, that's not how it works. The simplest answer is that the setup will only work as intended until you drain the old battery. When you put things in series the weakest link breaks the chain so to speak. What this means in practice is that once the old battery drains is that it will stop acting as an EMF source at... | [
"This is a great answer.",
"A decent analogy you can use is to imagine the electrical circuit to be replaced with four pumps one after the other trying to pump water somewhere. When all pumps are running they help each other push the water, and as a result you get more water through. If you shut off one of them, ... |
[
"How do computer alarms/alerts work?"
] | [
false
] | Is there a process in the background sitting there polling the time every microsecond and comparing it to the value of the alarm time? It seems like that would be a dumb way to do things but I can't think of how else it might be done. | [
"To elaborate a little. Most processors allow for interruptions. An interruption is either an internally or externally generated signal that tells the processor that something happened. This could be an alarm from a timer, a key press from a keyboard, or data connection. When a processor receives an interrupt reque... | [
"Well there are a few different ways. Operating systems having something called a scheduler which decides when various processes run and how much time they get. If you put an alarm program on your cell phone or laptop it will receive minimal time from the scheduler and only get a minimal slice of the processors tim... | [
"I've dont some programming, not a ton, but that's basically correct.",
"You computer has a built in clock that even runs while it is off (maintained by a battery on the motherboard). ",
"The simplest 10 second alarm clock (one that would not update it's time on the screen) would do:",
"ask user: how long ... |
[
"How is polyethene different from an arbitrarily long alkane?"
] | [
false
] | If you draw a structural diagram of polyethene, it seems exactly like a really long alkane to me... but long alkanes do not exhibit the same properties as polyethene, so how is it wrong to see polyethene as a really long alkane? | [
"long alkanes do not exhibit the same properties as polyethene",
"Sure they do, since they're the same. But polyethylene can have different properties depending on how branched it is (HDPE vs LDPE), and the average molecular weight of the chains in it, and the distribution of chain-lengths. "
] | [
"I get that, but the monomer in polyethene has no double bonds."
] | [
"The monomer of polyethylene has a double bond. The monomer is ethene (C2H4). During polymerization, the electrons from the double bond go to making a new bond with another monomer, so the polymer does not have any double bonds.\nI don't think there really is any difference between an arbitrarily long alkane and p... |
[
"If the force of gravity is determined by the mass of an object then how does a star, that is constantly losing mass in the form of energy, collapse into a black hole with a gravitational force many times that of the star's original state?"
] | [
false
] | Is there some other method of producing gravity? Or does the stars mass somehow suddenly increase to the point of collapsing into a black hole? If so, where does this mass come from? | [
"One thing your probably are not aware of is that, if you take a spherical shell of matter, the gravitational force will only be felt outside of that shell. Inside, there would be no gravitational force at all. Now, picture a star as a collection of concentric shells (a bit like the layers of an onion). The ma... | [
"Not completely. First you get heavier elements fusing untill iron, sometimes the core of those heavier elements just becomes too dense and make a black hole. ",
"So once you start fusing helium the core is actually helium not hydrogen with non fusing helium surrounding it than fusing hydrogen followed by nonfus... | [
"The gravity doesn't increase in the way you are assuming. Rather the forces inside the star push against gravity, when the reactions causing the force inside the star run their course and finish the star can collapse. By collapsing it creates a point of space with a high enough density that even light cannot escap... |
[
"Why does the Moderna vaccine include two 100 micrograms doses of mRNA, while that for Pfizer is two doses of 30 micrograms each?"
] | [
false
] | Considering the overall efficacy rate is comparable. | [
"Just a note, using \"MRNA\" to mean Moderna is pretty confusing in this context. I had to read it a few times to figure out what you were talking about."
] | [
"Basically, just in case. There's no other reason. Moderna could set their dose at 30ug (probably even lower) and it would work - they just didn't know that at the time so they wanted to play it safe instead of flopping."
] | [
"MRNA chose 100ug based on an early study. Later results showed their lower doses worked fine but the phase 3 was already designed.",
"MRNA vaccine had more adverse effects than PFE- Id guess because of the higher dose. But apparently there’s a non linear relationship between your immune response and the initial ... |
[
"Solids precipitate out of solution, but what do gasses do?"
] | [
false
] | To be precise, what's the word for a gas going from an aqueous state to a gas state? | [
"Outgassing",
".",
"@",
"/u/mavric91",
", ",
"/u/DrJesusHChrist",
": Evaporation is the process where the solvent goes into gas state, not the things dissolved in it."
] | [
"As Wikipedia says, outgassing includes evaporation. I had assumed that OP was referring to a chemical reaction (intramolecularly) rather than a state change. It seems I misunderstood, and focused just on one part of the whole."
] | [
"Nah, that’s still not it. Outgassing means coming out of solution ",
". Just coming out of solution would be exsolving, or perhaps vesiculation. "
] |
[
"How does one country export usable electricity to another country? especially at great distances?"
] | [
false
] | If a country has generated electricity to excess and wants to sell it what is the scientific (or technical) method that this is accomplished? Especially over oceans, mountains across different continents? Are there any other challenges or obstacles with this task? I would appreciate any other interesting facts about global electricity or energy trade (especially having to do with renewable sources) | [
"If a country has generated electricity to excess and wants to sell it what is the scientific (or technical) method that this is accomplished? ",
"No different than how power within a country's grid is distributed between consumers and the various generators. A transmission line is built two connect the two regio... | [
"Maybe not in the USA, but in Europe most countries have cross-border connections. Norway has a few ocean going DC links to Netherlands, UK and Denmark, and also grid links to Sweden.",
"Other countries also have transmission lines to it's neighbours."
] | [
"What's the reasoning behind keeping the grids out of phase? Did they just start independently and the work required to bring them in phase is just too great at this point?"
] |
[
"Are there examples where differences in quantum states have macroscopic consequences?"
] | [
false
] | The quantum world is, as we know, teeming with a fundamental uncertainties that are, in the language of several interpretations of quantum mechanics, resolved only when the wave-function collapses, when the quantum property is observed, etc. So an individual electron has a uncertain spin until we observe it, at which point we see it has spin up or spin down, yes? Are there any such quantum states where the outcome of this has classical, macroscopic consequences? (Other than the fact that you can measure them in a laboratory.) Or does it all average out? A dumb example of what I mean: if every electron in the Sun had the opposite spin than it does right now, would it matter at all? In most cases the answer seems obviously "no," and indeed it seems part of the Correspondence Principle is to say that this would be the case (that is, all of those quantum options, even where they might matter, just wash out to be essentially classical). I can think of very artificial ways to make it happen (e.g. Schrödinger's cat, where a quantum measurement device is attached to some kind of macroscopic consequence) but having no luck in imagining a situation where this would occur without clever human intervention. The closest I can come to is maybe thinking that in the case of cancer as a result of nuclear decay — the timing of decay seems related to a wave-function collapse (right?) and if the decay releases a gamma ray that happens to ionize the right piece of DNA it can result in a cancer. Even with this it seems like a bad way to think about it because the odds of any single radioactive decay giving someone cancer is infinitesimally low. Any and all thoughts, corrections, etc. would be appreciated. I am just a dabbler here, not a physicist, obviously. | [
"Well there's giant magnetoresistance. If electrons try to flow through a magnetic layer, they can readily do so if their spin is aligned with the magnet they are flowing through. If the spin is in the opposite direction, then it has to 'flip' to match the spin of the magnet.",
"On the macroscale this leads to a ... | [
"Thanks — it's not that I am looking for situations that illustrate the validity of quantum mechanics (I don't doubt that), it's more that I'm curious if there are situations where the ",
" in possible quantum states results in ",
" that matter on a macroscopic level. So, again, something like where an electron... | [
"If you want something that is not predicted classically that happens on the macroscale one need not look further than a superconductor.\nThey differ from classical ideal conductors in that they have no internal magnetic flux. It gets expelled out, is observable on the macroscale (I imagine you've seen \"quantum le... |
[
"How do you remove indium metal from a metal surface?"
] | [
false
] | We got indium on a copper surface and want to remove the indium without damaging the copper surface. Is ther anyway to do this with a solvent or anything from than mechanically peeling/scratching it off? | [
"You can oxidize it off in a dilute acid solution. I'd use 0.1M Sulfuric acid, with include 0.1M Copper Sulfate. Volume of solution needs to be calculated based on the amount of In you need to remove. Don't let the Indium exceed 0.05M or so.",
"Use alegator clips to connect your In coated piece to a sheet or snar... | [
"I spent several months doing an experiment where I melted indium on top of copper to use as a thermal contact material for silicon wafers.",
"If your copper was dirty, you're in luck. The indium will peel right off.",
"If your copper was clean, you're screwed. You will have to scrape it off with a razor blade.... | [
"You will most likely need to scrap or treat it with acid. If memory serves me correctly, Indium reacts with hydrochloric acid while copper does not. You might be able to dissolve it off if you are able to use acid. ",
"Though as always don't use acid without doing your safety and regulation homework first. D... |
[
"How to understand that Godel's Incompleteness theorems and his Completeness theorem don't contradict each other?"
] | [
false
] | As a layman, it seems that his Incompleteness theorems and completeness theorem seem to contradict each other, but it turns out they are both true. The completeness theorem seems to say "anything true is provable." But the Incompleteness theorems seem to show that there are "limits to provability in formal axiomatic theories." I feel like I'm misinterpreting what these theorems say, and it turns out they don't contradict each other. Can someone help me understand why? | [
"The completeness theorem says that any logical consequence of the axioms is provable. This means that we're not missing any logical rules, the ones we have are \"complete\". They suffice to prove everything you could hope to prove.",
"The incompleteness theorem says that any set of axioms is either self-contradi... | [
"This is very good thinking. This is ruled out in the premises of a \"workable set of axioms\" as the set of axioms needs to be recursively enumerable. If this premise is dropped, Gödel's incompleteness theorem would not be true for precisely this reason."
] | [
"But what if my set of axioms is an exhaustive list of every true statement about numbers?"
] |
[
"What's the difference between a negative pressure and a vacuum?"
] | [
false
] | null | [
"It's a semantic difference. You are creating a pressure gradient which drives a flow."
] | [
"Can you explain this to me like I’m 5? "
] | [
"If there's a difference in pressure between two positions, there is a force acting on the fluid in the direction of the lower pressure."
] |
[
"When people are suffering from a severe, and sometimes fatal illness (such as cancer), does \"fighting for your life\" actually do anything? Does a person's level of resolve to fight and survive actually play any role in their recovery?"
] | [
false
] | null | [
"An optimistic attitude is associated with better health outcomes. ",
"Research seems to show this is because optimistic people participate more actively in their own care, and seek opportunities to improve their health. That is, it's probably not the attitude itself, but the way optimism makes you behave. ",
"... | [
"Super interesting. I understand that having a positive outlook will lead you to make better choices (such as quitting smoking or changing your diet) in illnesses like hypertension and diabetes which can be directly caused by lifestyle. I was really curious if the power of optimism and hope like the authors of the... | [
"There's a specific study on this that found it doesn't have an impact. I'm not across the literature enough to know how this fits in to the overall science though;",
"https://www.webmd.com/cancer/news/20040209/attitude-doesnt-affect-cancer-survival"
] |
[
"If our star system was near (relatively) a dense nebula, would we see blue skies during the day, but amazing swathes of color at night?"
] | [
false
] | And if it was sufficiently dense, would it be obviously very far away? i.e. could we look at the moon & think 'yeah, that's the moon & it's a very long way away, but that nebula is REALLY far away'? I would imagine that sort of view at night would give us a completely different perspective of the universe. the scale would be immense. of course, we don't really think of the stars as far away, they're just dots of light in the dome of night. at least, that's the way I see them, unless I think about it. maybe we'd perceive a nebula in the same way. | [
"Amateur astronomer here. Not actually a scientist, I just looking at cool stuff through a telescope.",
"No. Nebulae are too dim. Being closer to a nebula wouldn't make it brighter, just larger, and making it larger wouldn't the cone cells in your eyes detect color in them. There are plenty of nebula in the sky t... | [
"Let's talk about what \"brightness\" means, because it can mean multiple thing depending on context. It is not really a very useful scientific term because of how loaded it is. I apologize for that; I should have been more rigorous.",
"Objects appear \"brighter\" when they get closer because they appear larger. ... | [
"The closer you are to a source of light the brighter it gets so it would in fact make it brighter. "
] |
[
"Could concentrated injections of B lymphocytes be a solution to cure cancer?"
] | [
false
] | null | [
"There is plenty of research looking at using the bodies own immune cells to combat cancer, you suggest. B cells are not the main cell of interest for this however. B lymphocytes tend to be more associated with combating humeral diseases, small things in the blood. ",
"The cell we generally want to kick into acti... | [
"Is this specific to CD8+ T cells, or are there other T cells who partake in killing cancer cells, except for activation?"
] | [
"CD8+ are the main cells that mediate specific cell killing, which is generally what we want in cancer or viral infections.",
"If possible we also want CD4+ Th2 helper cells activated, as they promote CD8+ killing, but don't attack the cancer cells directly themselves.",
"There are a number of T cell types that... |
[
"Why is oxygen paramagnetic while iron is ferromagnetic?"
] | [
false
] | Ogygen and iron atoms both have unpaired electrons. Why can these unpaired electrons keep existing in iron (making it magnetic) while they can't do this in oxygen? | [
"Because the atoms of iron exist within a periodic lattice. And the unpaired electrons on adjacent iron atoms align with one another due to the exchange interaction. The oxygen molecules in the gaseous or liquid state take essentially random orientations with respects to each other.",
"Exchange interaction: essen... | [
"While your second paragraph is absolutely correct I disagree with the first one a bit. Yes, a lattice is important for ferromagnetism but it does not guarantee it. Vanadium has 3 d electrons, yet it's a paramagnet in bulk. So is manganese. In Fact, the only ferromagnetic (at room temp) bulk materials are Iron, nic... | [
"Below its curie temperature, each Material will be ferromagnetic and above it, ferromagnetic",
"Good answer, but should that read \"and above it, ",
"\"?"
] |
[
"Would it be (theoretically) possible to use the heat in the air to generate electricity effectively enough that it would cool the air significantly?"
] | [
false
] | The reason I'm asking is because if it was possible you could create an air conditioner that would generate electricity. | [
"No, it's only possible to generate electricity through heat differences. Thermoelectric devices work by producing a voltage across a material that has a different temperature on both sides of them. In space satellites, this is achieved with radioactive pellets.",
"Essentially, in your example, you would need t... | [
"You're laboring under a misapprehension, that \"heat in the air\" is a form of energy that can be harnessed.",
"First of all there's no such thing as \"heat in the air\". There's the ",
" of the air, and there's thermal energy in the air, but heat is a transfer of thermal energy (of any kind) from one thermod... | [
"Every heat engine operates off of a temperature difference. (I.e., the Stirling engine is not particularly special in this way.) No heat engine can remove thermal energy from a system except by sending at least some of it to a lower-temperature system. "
] |
[
"At an altitude of 1470km, how fast is Dawn traveling, orbiting Ceres?"
] | [
false
] | null | [
"TL;DR answer: an average of 179.6 m/s, relative to Ceres, ignoring Ceres' rotation.",
"Orbital parameters aren't immediately obvious on JPL's web site, so I'll assume we're talking about a uniform circular orbit. As outlined at ",
"physicsclassroom.com",
", this can be modeled with the simplified satellite e... | [
"Thank you for the details! 180m/s is not that fast, I'm surprised."
] | [
"No worries. Its gravity is a measly .03g, so it doesn't take much to orbit. :)"
] |
[
"#eng Why are I6 engines considered so highly balanced but a V8 isn't?"
] | [
false
] | There are 4 strokes in a complete cycle, so shouldn't an engine like a V8, which is an even multiple of four, be able to cancel out the forces generated by each piston by virtue of the fact that another piston must also be doing the exact opposite motion? | [
"reciprocating mass connected via two links have something called shaking force (think of a motor in your phone allowing it to vibrate). With even number of cylinders the force can be balanced. However, this doesn't account for the moment caused by the shaking force. Two pistons opposing the shaking force is at dif... | [
"Why ",
" a I6 engine naturally balanced but I4 and I8 engines are not?"
] | [
"An inline engine has all cylinders in the same line (like this: | | | | | |), so the up-down motion of the pistons can be balanced. A V engine has cylinders at an angle to each other (like this: \\ /). V8 has two banks of 4 cylinders on each side of the V. The motion of the pistons is partially up-down and partia... |
[
"If the dinosaurs hadn't been wiped out, what would the world look like today?"
] | [
false
] | Would we still have evolved to be the dominant species or would they have eventually developed intelligence and became dominant? | [
"Intelligence isn't necessarily an advantageous trait to develop, and certainly isn't the end goal of evolution. There's no reason to think that they'd develop it given enough time."
] | [
"More dinosaurs, mostly.",
"Dinosaurs were around for 160 million years, and died out around 65 million years ago. That isn't such a huge gap considering their long evolutionary lifetime. In contrast, we've been around for 50,000 or so.",
"Edit: Fixed for correct time."
] | [
"Don't you mean 65 million years ago?"
] |
[
"How did people before modern times deal with torn acls?"
] | [
false
] | In addition, there was a story about in nba player Dejaun Blair who was able to sustain a career for a period of time without an ACL. How is this possible? He is also not the only one. | [
"When I tore mine, the physio said that I can get surgery, or I can do a lot of work to strengthen up all the muscles from my ass to my calves to prevent my knee going backwards again. There's no guarantee though. I'd say if people are already elite athletes, they're in a great position for strengthening already. O... | [
"Depends what you mean by modern times I would think, for example if you think back to the 1800’s I’m sure there were less acl injuries due to less intensive sports I would imagine, but in terms of more recently, I believe treatments for torn ACLs was developed in the 1970s at some point. Before these treatments I ... | [
"Full ACL tears cannot be healed without surgery. A pre-surgery-option person would be injured for life. ",
"However, very minor tears can heal on their own over time (months-> years). Ligament tissue heals really slowly. An injured person will be limited to activities that don't involve pivoting on the knee.... |
[
"Is solar wind energy at all possible?"
] | [
false
] | I remember reading something around Reddit some time ago about the theoretical possibility of harnessing solar wind in order to create energy for practical human uses, like we do with wind turbines or solar panels. Is there any reality behind this idea? I've had little luck finding much of anything on this, as it seems to be more of a proposed idea. Any idea where I could find more information/research? Cheers. | [
"Its possible, but I suspect that the solar wind is too diffuse to make harnessing its energy a viable option. I also suspect that there is a much higher density of solar energy from light than there is from the solar wind."
] | [
"I don't think that solar wind will ever be a terrestrial power supply. I don't think solar winds even get through the magnetosphere. ",
"It might be used one day as a way to get around the solar system. You don't have to carry fuel with you."
] | [
"Not quite solar ",
" but somewhat relevant: ",
"Dyson Spheres",
"."
] |
[
"If I leave my phone in the sun it gets pretty hot very quickly. Would this happen more slowly if the screen stayed on a white screen?"
] | [
false
] | null | [
"No.",
"You're right that white things stay relatively cool under intense sunlight, but that's because they ",
" light and avoid absorbing it. A phone's screen is ",
" light instead, so colors are irrelevant for controlling the temperature. Rather, you should cover your phone with a white reflective surface (... | [
"Not really. The pixels aren't 'colored white'. There are actually 3 different pixels (red, green and blue) that are all lit up to trick your brain into seeing white. So all in all, you still have the exact same non-white pixels absorbing not only the Sun's energy, but also the backlight."
] | [
"What's the difference between ",
" and ",
"? Isn't it just colored pixels with a backlight, instead of reflected light?"
] |
[
"What has a greater effect on melatonin levels, light intensity, or the tint of the light itself?"
] | [
false
] | It seems common knowledge that light in the blue spectrum has a significant impact on our melatonin levels, which can lead to decreased sleep quality. But would a bright light in the red spectrum have a similar impact? | [
"A common model is that what matters most is the amount of light in the blue-green range, most strongly in the 400 nm to 500 nm range, and tailing off somewhat gradually beyond there. However, some recent work indicates that the relative spectral power does matter, and it's not that simple. [1] has some plots and... | [
"if you have light that is just red, that will have little effect, even if it's bright. But it's not only blue that has an effect: green, depending on the particular spectral distribution, can have a substantial effect as well. ",
"OP, just to follow up on this good answer with some of the biological details... | [
"Awesome, that's really interesting. Thanks for the great response!"
] |
[
"If a solar panel isn't connected to a power grid, what happens to the electricity generated?"
] | [
false
] | null | [
"If a solar panel is in the sun but not connected to anything, it will maintain its normal voltage but no current will flow (because there's no complete circuit for it to flow through).",
"It's exactly analogous to having a battery with nothing connected. Same voltage as normal but no current flowing.",
"Using ... | [
"Absolutely not true. Most of the world's solar capacity is connected to the grid, not batteries. (And yes, grid-scale backup batteries do exist but they're kind of fringe, and the connection between them and solar panels is not at all direct.)",
"You only need a battery if you're off the grid, or otherwise need ... | [
"As ",
"/u/cuicocha",
" points out, no current will flow. ",
"Interestingly, this means that if you were to leave a connected panel and a disconnected panel out in the sun, the disconnected panel will get warmer since none of the energy hitting it is leaving via the wires."
] |
[
"who would win a zipline race - a heavier or lighter person?"
] | [
false
] | [deleted] | [
"The heavier person would. If they have the same drag, it would affect the lighter person proportionally more than the heavier person."
] | [
"so if you dropped two balls with the same coefficient of drag but different masses, the heavier one would always hit the ground first?"
] | [
"Yes as it has more mass the drag force has less of an effect on it due to F/m=a."
] |
[
"Sarcopterygii, Myxini, Cephalaspidomorphii, Chondrichthyes, Sarcopterygii - why all the \"fish\"?"
] | [
false
] | [deleted] | [
"The unsatisfying answer is that \"fish\" is not really a technical term as far as taxonomic classification goes. I've heard conodonts and even protoconodonts referred to as fish by people who are into taxonomic hairsplitting with the fire of a thousand suns. Same with whales.",
"If you've been introduced to the... | [
"Taxonomy is such a mess. I learned three different classification structures, just during my grade1->b.Eng. But what's beautiful about that is we can easily permute the trees depending on the most currently accepted lineage. I think of it like some gigantic program that can be patched whenever 'bugs' around found.... | [
"You repeated Sarcopterygii, you probably meant Actinopterygii for one of them ;)",
"There isn't really a one-sentence way to distinguish them other than that they are different branches on the vertebrate tree of life. ",
"And why do frogs, reptiles, birds and mammals only get one class each?",
"This has to d... |
[
"Why do we shake when we flex a muscle and hold it still?"
] | [
false
] | I often find that whenever I flex and hold a part of my body still (such as my leg) it tends to shake/vibrate. Why does this happen? | [
"When you are holding your leg out, your muscles will become fatigued. When our muscles are flexing, the muscle fibers sort of take turns holding up the weight, switching on or off - this is called a 'twitch.' When we start to become fatigued, these muscles do not have time to fully relax between each twitch causin... | [
"When you first start strength training for weight lifting it is common to see very fast increases in the amount of weight that can be lifted. These increases are faster then muscle can be built. These increases come from neural adaptation. Essentially you are training your neural system to synchronize the firin... | [
"I am happy to provide!",
"Zatsiorsky, V., Kraemer, W. Science and Practice of Strength Training. Champagne: Human Kinetics, 2006.",
"Walker, A. \"The Strength of Great Apes and the Speed of Humans.\" Current Anthropology. 1 Apr. 2009, Volume 50, Number 2: 229-234.",
"\"There is also the upstream control of m... |
[
"Did they need glasses?"
] | [
false
] | Dear Reddit, I now need glasses to see things up close, like reading this post. I hate that! Anyway, it led me to ponder if the eyesight of man has evolved over time. Given Neanderthal people did not have the need to read, did they have eyesight that enabled them to see fine detail up close, like we can? Or was their eyesight only developed to a point that enabled them to see large detail? Just pondering. Edit. Many thanks for all the input. Very interesting. | [
"lack of selective pressure",
"IIRC not at all that. There were comparative studies between Jewish children in Israel. They compared those growing up in a Kibbutz and were outside a lot, and those who attended religious schools to reading the Torah a lot.",
"They found that the latter suffered more from myopia... | [
"I do not think that reading has been a factor in the evolution of our eyes to be able to focus at short distances. I would think most creatures with eyes can focus well at arm, claw or tentacle length. Compound eyes exempted perhaps.",
"That poor eye sight is common among humans probably has more to do with incr... | [
"Their eyesight was probably similar to ours. However:"
] |
[
"If the Beta(1,4) bond in cellulose is hard to break, does that mean it was hard for the plant to make it as well?"
] | [
false
] | null | [
"AFAIK, the beta(1,4) isn't actually a stronger bond than the alpha(1,4) linkage of amylose (normal starch). Rather, we just don't have an enzyme that can do the reaction (and such enzymes are apparently relatively uncommon in nature, maybe it's a hard shape for enzymes). I don't actually know the energy expenditur... | [
"Not necessarily. The strength of a chemical bond is not equal to the work it requires to cause the bond to form. Some bonds, like between two individual hydrogen atoms, form spontaneously without any real external effort but are incredibly resistant to breaking. "
] | [
"Apart from the fact that very few organisms have an enzyme to break down the beta (1,4) glycosidic bond, cellulose is relatively difficult to break apart. The glycosidic bond itself is actually relatively easy to cleave with acid in either cellulose or amylose. The big problem with cellulose is that it forms a cry... |
[
"What causes arthritis?"
] | [
false
] | So I've been digging through the Ask Science sub-reddit, and I've seen a lot of "does cracking your knuckles cause arthritis?", "why not?", etc. But I haven't seen a "What causes arthritis?" so I'm asking. Is it a virus? Genetic defect? Wear and tear? Bacteria? Symptoms of injury? Diet? I've heard about the various types, but never a solid cause. | [
"There are quite a few different causes for arthritis. The two most prominent that come to mind are rheumatoid and osteoarthritis. Rheumatoid is an autoimmune disease where the immune system, which normally should not be sensitized to the joint capsule, gains immunity against it and attacks joints. Rheumatoid arthr... | [
"To add to the OA discussion the spine works a little differently than most other joints due to the presence of discs. In spinal osteoarthritis the first phase is damage of the cartilage end plates of the disc/vertebra, this produces a decreased nutrient flow to the nucleus pulposus of the disc (it gives the disc ... | [
"There is no one set cause of arthritis. There are only risk factors, and all of the things you listed plus things you can find on the arthritis ",
"wiki",
" can predispose you to getting arthritis. There are also over 100 types of arthritis. This is such a complicated area that there is an entire field dedicat... |
[
"Will a piece of wet laundry dry faster if I throw it in the dryer alone, or together with other, already dry textiles?"
] | [
false
] | Sometimes I need a certain piece of cloth to dry as soon as possible. I assume having towels in the dryer could work as they absorb the humidity and distribute it, whereas the additional load may also block the airflow. | [
"It will change the dynamic - it will get partially dry faster, as the other textiles absorb moisture from it, but it will take longer to get completely dry, as they block airflow around it. Finding the optimal amount to include is an extremely complicated and idiosyncratic problem that depends on the materials in... | [
"If I just have one garment to dry, I always dry it with an already clean and dry towel. I have found that it is typically much faster this way. The reason is that there are usually a few lips/humps inside the dryer to help the clothes mix when drying an entire load. If you just throw one garment in, these will som... | [
"In my particular case, I often want to dry a piece of cloth, several meters long, made from woven cotton. The already dried fabric that I would add consists of several pads made from microfiber terry cloth."
] |
[
"Could someone actually use a smart meter to spy on one's computer?"
] | [
false
] | Okay, hear me out: I just read Neal Stephenson's and there was a part in there with something called "Phreaking." As I was reading cyberpunk, I was unsure as to whether this was hypothetical or an actual technique. Anyway, I read about smart meters, and it just tracks usage and reports the data through an RF transmitter. I was wondering if someone sneaky wanted to, could they intercept the data and translate the changes in power usage into the rastering of a monitor, effectively capturing the screen output? Edit: I just realized that I not only gave an anecdote, but also commited the crime of speculating as a layman. I appreciate the fact that I haven't been deleted. | [
"It is possible. The general technique of determining what is displayed on a monitor from its EM emission is called Van Eck phreaking [1]. The general technique of attacking 'secure' systems through indirect means is called side-channel attack [2]. Another example of a side-channel attack is using microphones to de... | [
"I'm kind of geeking out right now. Thanks!"
] | [
"how does the meter capture a wide band of EM radiation?"
] |
[
"Why are asteroids all different shapes, but planets and moons are mostly round?"
] | [
false
] | null | [
"Planets, some moons, and dwarf planets are big enough for gravity to be strong enough to pull them together. Systems tend toward their most stable state over time and that is one where potential energy is minimized- ideally, a sphere. Rotation can bulge mass around the equator creating an oblate spheroid. ",
"It... | [
"This.^",
"The reason why planets amd moons are round is that the higher gravity from all their mass pulls them into a sphere. The reason it turns into a sphere is that any high points tend to fall/shift towards the center of mass. This keeps happening and gets you a sphere instead of a cube, disk, or otherwise."... | [
"This.^",
"The reason why planets amd moons are round is that the higher gravity from all their mass pulls them into a sphere. The reason it turns into a sphere is that any high points tend to fall/shift towards the center of mass. This keeps happening and gets you a sphere instead of a cube, disk, or otherwise."... |
[
"How do hydraulic systems amplify force?"
] | [
false
] | null | [
"Hi ThePreaux thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the follo... | [
"‘Engineering’, ‘Physics’"
] | [
"Engineering, Physics"
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.