title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Could I get a more clear and in depth explanation of the cosmological constant?"
] | [
false
] | So I just watched and really enjoyed it. Although it's a little bit out of date now, it gave me a better grasp on what exactly was discovered by the LHC and a better understanding of the Higgs Boson and the competing theories surrounding it (Supersymmetry vs. Multiverse, etc.) The biggest question I came away with was, what exactly is the cosmological constant? Why is it so important and what allows it to dictate so much of the physical nature of our universe? I think I understand that it defines the energy density of the vacuum of space. My basic understanding is that this means that this value is sort of the sweet spot where matter will sort of reach an equilibrium in interstellar/intergalactic space in terms of the density of particles? Is that on the right track? Just to clarify, I'm not a scientist by any means but have a pretty strong grip on Physics/Astronomy from a layman perspective, or at least I think I do lol. Thanks! | [
"Basically gravitation can be concentrated in the Einstein field equations, which are",
" = constant ",
" is a tensor representing curvature, and ",
" is the stress-energy tensor of the contents of the Universe. So, the energy-momentum content of spacetime makes it curve.",
"(the constant is actually 1/the... | [
"To try and put this in perspective:",
"There is an experiement which demonstrates something called the casimir effect. This is basically where two very very thin (Low mass) metal plates are placed very close together. The gravitational attraction is designed to be almost 0, and so is the electromagnetic, and van... | [
"I think you are on the right lines. From my research, the casimir effect is seemingly the best \"fit\" for what we think the cosmological constant is (A kind of outwards pressure spreading the universe apart at an accelerating rate). However that error of 120 orders of magnitude is just too damn high (:P). Either ... |
[
"can plants get \"fat\"?"
] | [
false
] | as in make more energy than they use and store it on their body? Or is it all well regulated? I know some plants can store energy in roots (potatoes I think?) so is this what they do instead? | [
"There are some issues with terminology, but in a sense, yes! They do make energy and store it, and in a somewhat parallel way to humans",
"In humans, we store energy (generally) in two forms - fat (adipose tissue) and carbohydrates (",
"Glycogen",
"). Glycogen is what we call a \"polymer\" of glucose blocks.... | [
"Perhaps the only downside would be that animals would be more likely to eat them to use the starch. But plants have known this for millions of years; why do you think they make sweet fruits around their seeds? "
] | [
"are there any adverse effects for a plant which stores an abundance of starch? (strain on structural or vascular systems, etc?) Or is it like a savings account for them, where having more stored (\"fat\") is only positive?"
] |
[
"Question on diffusion in respiration"
] | [
false
] | [deleted] | [
"Wait, how do you know P02 in the lungs remains the same? We inhale air, of which approx. 20% is O2, and exhaled air contains approx. 15% O2.",
"Take a deep breath and hold it in. You are using that oxygen right now, but the total pressure remains the same because you closed the system by holding your breath. The... | [
"Unless you have a heart attack, the blood in your lungs is in constant motion. You should never get a chance to reach equilibrium with the outside.",
"On the other hand, with the second part of your question, you have anticipated the need for hemoglobin in blood. We cannot simply rely on diffusion to keep us a... | [
"The pO2 does change; the degree to which it changes varies greatly depending on the person doing the breathing, what the person is doing, and environmental conditions (temperature, humidity, etc). Typical, resting exhaled breath will have around 15-18% oxygen in it. "
] |
[
"Why does some metal turn red when heated?"
] | [
false
] | I was roasting s'mores with my family one night when we decided to put on a cage-like cover. After a minute or two, the metal was red, and I questioned this for the first time. I want to know what exactly it is that makes it the red color. Can anyone help? : Thank you all so much! Your answers are exactly what I needed. | [
"This is one of the most important questions in physics",
"."
] | [
"The metal \"wants\" to lose the heat (energy). It can do so by emitting energy as light.",
"Remember Roy G. Biv? Those letters represent the colors of visible light, from the visible light with the least energy (red) to the visible light with the most energy (violet). And I repeat, that's just ",
" light. Befo... | [
"OOO just said it will start ",
" those colors, which is true. It just doesn't look like it because it's also emitting all the ones below it as well."
] |
[
"By what mechanism are the minature transistors inside a modern microprocessor turned on and off?"
] | [
false
] | I was trying to comprehend how a modern processor works today, and I realized I had one critical piece of information missing. I know that at the smallest logical level, a processor is a very large array of transistors arranged to create discrete components like adders, memory, opcode decoders, etc. I also know that it is the action of turning on and off these transistors which decides the machine's state. My question is specifically, HOW does a computer cause that switching action to occur? Meaning, what physically happens that makes the input line of the transistor high or low? | [
"Taken to the limit, almost every transistor in a CPU is going to be gated by an output of another transistor in the CPU ",
" an external signal (from say an oscillator that provides a clock, or an input port) ",
" be effectively ungated by being tired to a rail in some scenarios (always on or even more rarely ... | [
"Yep! That's how transistors work. Unfortunately, that's not the question I was asking."
] | [
"The basic idea is that metalloids, such as silicon, can behave both like metals and non metals (i.e. conducting or non-conducting). With silicon you can make a semiconducting transistor, which can be made both to conduct or insulate depending on if you apply a base current to it or not.",
"A simple transistor ha... |
[
"Why does a rainbow split light into discrete colours rather than a range of the whole visible spectrum?"
] | [
false
] | A rainbow consists of definite bands of colour rather than and infinite gradient of changing colours. | [
"A rainbow ",
" consist of a continuous spectrum. You may ",
" it to contain discrete colours, but the quantization is the result of your perception, not how a rainbow splits.",
"For example, you can look at ",
"this sample spectrum",
" and pick out a set of colours, but there is much more displayed than ... | [
"Plus much more than what your monitor can display correctly :)"
] | [
"By the way, the spread of colors in a rainbow is not a pure spectrum (although it is indeed continuous and not banded) because of the way a raindrop scatters a certain color in multiple directions, causing mixing. Also, the extended, non-point-like, nature of the sun contributes to color blurring. In contrast, the... |
[
"How do fish heal underwater? Why don't they bleed to death? Also, are there less infections for underwater cuts?"
] | [
false
] | Not just little fish, but sharks and rays as well. | [
"Fish heal much like we do: a lesion occurs, immuno-responses occur, skin regenerates.",
"What's protecting them from infection is a few things. 1) slime coats that shed off bacteria and parasites, 2) scales, 3) tough skin. ",
"Slime coat is interesting because the slime coat is constantly secreted and repl... | [
"This is normal and very common in fish. Here's an awesome paper that tells you everything about the subject because 1) it's really cool, and 2) it'll take forever for me to shut about fish.",
"http://salamander.uky.edu/srvoss/425f09/Shao_et_al.pdf"
] | [
"I'm not him, but I might know the answer.\nFirst off, evolution is probability, not purpose. The one who reproduces more (often) isn't necessarily the strongest, or fastest. It's the combination of being more apt and being lucky.",
"Second, and more to the point: Regeneration is a very energy/matter and time exp... |
[
"Can you detect a ruptured eardrum with altitude pressure?"
] | [
false
] | null | [
"As someone that has had their eardrum burst, you will know if you have your eardrum burst. It hurts like hell and the best way I can describe the sound change is that it sounds windy all the time. I was kneed in the ear while underwater, the pressure of the water burst my eardrum."
] | [
"Most traumatic ruptures of the eardrums heal within a week. Barotrauma as you are describing only results in perforation if the change in pressure is large enough. You might just have experienced great movement across your tympanic membrane resulting in pain, either that or the membrane healed quickly. Did you exp... | [
"You are assuming that the rupture is big enough that the pressure difference of exterior vs interior is immediately equalized. It could well be that the tear is small enough that the pressure buildup is still noticeable."
] |
[
"How big would Noah's Ark have to be to house two of every species of animal?"
] | [
false
] | null | [
"It was removed because of the issues I mentioned, but the best answer was probably:",
"Warning: I'm having to make a few assumptions here.\nIf [1] these numbers are correct, there are a 933,253 animals that would have had to go on the ark. That's after you subtract the fish, mollusks, crustaceans, and corals. I ... | [
"This was asked two weeks ago - unfortunately, the number of off-topic replies meant we had to shut the thread down. It's probably not a good idea to let this out into the open so quickly :/"
] | [
"Oh sorry about that. Do you remember what the answer was? I did a search and it didn't come up. Thanks"
] |
[
"When birds pull their wings down they get pushed up into the air. How come when they push their wings up, they do not descent the same amount they flew up?"
] | [
false
] | null | [
"The movements of the wing are more than just an up and down motion, which is covered briefly in this paper looking at how ",
"wing stroke changes as birds grow to adulthood",
". This is why they also have the ability to fly up and forward, and in some cases ",
"hover and fly backwards",
". ",
"Both the ... | [
"Because they change the shape of their wings as they move, creating the conditions for lift. ",
"They also change the amount of air that can pass through the wings at any one point. ",
"This video",
" is really good at showing how the feathers change through the cycle. ",
"But the video is not correct (i.e... | [
"When you're swimming, and you push your arms down to your side to propell forward, why don't you move backwards the same distance when you bring your arms back up for another stroke?",
"Because when you bring them up, you bring them up close to the body and presenting minimal area for wind/water-resistance in th... |
[
"Why can't we eat wood?"
] | [
false
] | I understand that we (humans), can't digest wood because our digestive tract doesn't contain the necessary bacteria ect... Why can't we add the correct prokaryotes that termites etc... use to our bodies to make use of all the woods? Om nom nom. *edit, Could we be made to? What would it take? | [
"We lack the digestive enzymes necessary to break down the polysaccharide, cellulose, that makes up the fiber of wood.",
"As for why we haven't taken on a set of prokaryotic symbionts... the answer is evolutionary- i.e. wood doesn't taste good to us, it wouldn't provide nutrients that we couldn't otherwise get, w... | [
"Rabbits eat their poo, but cows upchuck the food.",
"Also, technically, it's not the cow that digests cellulose, but symbiotic bacteria. No eukaryote can digest cellulose."
] | [
"Rabbits eat their poo, but cows upchuck the food.",
"Also, technically, it's not the cow that digests cellulose, but symbiotic bacteria. No eukaryote can digest cellulose."
] |
[
"Why do streams seem to originate from mountain tops?"
] | [
false
] | At least here in Japan, most streams emerge from the ground quite near the tops of mountains. Even relatively small mountain tops (area-wise) will have a continuous stream emerging some 30 meters down from the peak. This, of course, joins with other streams emerging farther down or from other mountain tops and that is the source of almost all of the rivers I have seen here. So, my question is, is all that water emerging near the peaks from rain which actually fell on those peaks? (And is then just percolating down, following gravity, and happening to find a crack for an outlet?). Or, is there some other mechanism in which the water is actually forced up toward the tops of the mountains, gravity, before it finds an outlet? I spent more than an hour searching google for this but wasn't satisfied by the answers I found. TIA. | [
"Higher elevations are generally colder than lower elevations. On the windward side of the mountain, wind (caused by air pressure differentials) pushes air up the side of the mountain until it reaches the point at which the air can no longer hold the moisture. Cold air can hold less moisture than warm air. So, w... | [
"Hence the underlying question \"How did it get uphill?\""
] | [
"The simplest way to go about this would be starting with the ",
"hydrologic cycle",
". So essentially water evaporates, is transported by moist air over land and water is delivered as rain. ",
"The next step is why does it rain? Wind moves the moist air over land, where it may rain. For rain to occur, the mo... |
[
"Is there a healthy way to prolong sleep?"
] | [
false
] | I always wake up too early and I feel that I chronically don't get the sleep that I need. After waking up I feel like I was hit by a truck and I can't fall asleep again. It's been lasting for years now and it really is very serious. It stresses me, I get fatter, my brain is always fatigued. In the mornings I often have morbid and unpleasant dreams. Maybe it's somehow relevant. I know it doesn't sound like much but if this could change my life would improve dramatically. Besides that I'm not stressed, my diet is ok, I rarely drink, don't smoke, play sports, I am in my twenties. I tried a lot of things (like: not eating before sleeping, changing bedsheets everyday, wearing sleep masks, earplugs) and nothing helps. Any advice? | [
"I have some sort of a disorder ",
"Why do you keep going back to this? I keep telling you that based on what you're saying you need better sleep hygiene, as it sounds that you have a form of insomnia, and the BEST treatment for insomnia is sleep hygiene. If you truly believe that you have a disorder then this ... | [
"This is bordering on medical advice, so if people think it is, I'll delete it. Anyway: Go to bed earlier. Many people mess with their natural sleep drive by staying up later than they should, and get angry when they don't sleep in as late as they'd like. Some of it likely has to do with sleep drive, and another... | [
"Any casual advice for a mid-twenties guy who both can't seem to get to sleep or get up in the morning? "
] |
[
"Elon Musk once said that Rockets won't be able to run on electricity because of Newton's Third Law. Is this true?"
] | [
false
] | Source: Elon mentions it around 2:20. | [
"It's true for any practical purpose. Conservation of momentum (which Newton's third law expresses) requires some mass to be expelled from the craft. A caveat here is that more momentum can be achieved by using a higher exhaust velocity (which is why we bother to burn propellants instead of just pumping them out)... | [
"Cars have a road to push off of. Rockets use their exhaust gas to \"push of of\" and move them forward."
] | [
"Friction on the road.",
"Rockets have no friction in outerspace, as in they have no road to grab on. "
] |
[
"When was the last time molten lava was naturally present on the surface in the continental USA?"
] | [
false
] | I know the lower 48 states have lots of volcanoes, particularly on the west coast, and there have even been some relatively recent eruptions (most famously Mount St. Helens). But to my knowledge, those recent eruptions have been explosive gas and ash, not lava. The presence of massive ancient lava flows in states like Idaho and New Mexico indicate that volcanoes with lava do exist in these though. Basically, what I'm wanting to know is when the last time there was a Hawaiian-style eruption with flowing lava, and/or molten lava present on the surface, even if not part of a major eruption -- there's not a place like this in the continental USA currently, right? | [
"I don't have a definite answer, but the youngest basaltic lava flows I can think of in the contiguous United States are at ",
"Craters of the Moon National Park",
" in Idaho. The youngest flows there are about 2250 years old."
] | [
"The last time a basaltic volcano erupted in the lower 48 was about 720 years ago, at the black rock desert volcanic field in Utah.",
"There are many, many volcanoes in the western US due to the great basin's extension. "
] | [
"Are you asking about the contiguous US or continental US? I only ask because you mentioned the lower 48. Technically Alaska is part of the continental US, and it looks like there were several reports earlier this month regarding Mount Veniaminof and lava flows."
] |
[
"Are all ants in a colony genetically same?"
] | [
false
] | [deleted] | [
"Similar, but not the same. Precisely how similar depends on a whole bunch of details.",
"If an ant colony has only one queen, the workers are all sisters. During her youth, before the queen founded the nest, she mated with one or more males. (The ant mating season is when you see winged ants flying around; those... | [
"No, she was never a worker. Because she was fed a special diet as a larva, she was born with wings and functional reproductive organs.",
"And yes, when someone tries to use animal sexual behavior as a moral yardstick for human sexual behavior, it seems unlikely that that person is aware of the stunning and bizar... | [
"So, is a male ant basically a clone of the queen, just male?",
"Not quite a clone. He only contains half of his mother's genetic variation, so she's 50% related to him, just like my mother is 50% related to me... but he also contains no ",
" genetic information that ",
" come from his mother.",
"Like, the ... |
[
"Why does metal (i.e. a metal spoon) get hot when it’s bent?"
] | [
false
] | null | [
"Because you are putting energy into the spoon, and deforming past it's ",
"elastic limit",
".",
"The force you apply multiplied by the distance you bend it is Work. This Work MUST be conserved. This Energy goes into Potential energy of the elastic deformation, and all the rest goes into heat (in the end)."... | [
"All metals do. It's just that some are easier to bend so take less energy to do so. Other metals fracture in a brittle fashion before they can deform much."
] | [
"Adding to this question, why not all metals show this behavior (at least in the same magnitude)?"
] |
[
"i have chickens. they wander about all day long and interact with one another. how much do they know about what theyre doing?"
] | [
false
] | is everything they do an empty-headed chemical instruction? what about when they walk over to another chicken and cluck at them then walk away? was that "thought" about at any level? mind boggling. | [
"Keep discussion on topic and focused on answering questions scientifically.",
"Please keep discussion civil. Name calling, insults, racism, sexism, etc. will not be tolerated.",
"Please follow the ",
"r/askscience",
" postig guidelines."
] | [
"Keep discussion on topic and focused on answering questions scientifically.",
"Please keep discussion civil. Name calling, insults, racism, sexism, etc. will not be tolerated.",
"Please follow the ",
"r/askscience",
" postig guidelines."
] | [
"Keep discussion on topic and focused on answering questions scientifically.",
"Please keep discussion civil. Name calling, insults, racism, sexism, etc. will not be tolerated.",
"Please follow the ",
"r/askscience",
" postig guidelines."
] |
[
"If I want my oven to get to 100C, will it get there faster if I set it to 200C?"
] | [
false
] | null | [
"Depends on what kind of controller the oven has. If it's a simple on/off (i.e. if the temp is below a certain setpoint, turn heater on, and if above, turn heater off), then no. If it has some sort of proportional control (i.e. the amount of heat being generated is proportional to the error between the temperature ... | [
"i can't see any real benefit from a \"proportional control\", so i would assume they are all the \"on/off\" type "
] | [
"If it's testable, it's worthy of scientific investigation, all questions lead to enlightenment. "
] |
[
"Which way should I face the opening in my disposable coffee cup while driving to minimize the chance of spilling?"
] | [
false
] | When putting my coffee cup in a cupholder, I usually face the opening towards the back of the car (6 o'clock). Sometimes if I know I'm not going to make a left turn, I might face it toward the right (3 o'clock). What's the most efficient way to set my cup down to minimize the probability of it spilling? I started thinking about other possible solutions like 7 or 8 o'clock positions since I never really accelerate at an angle. | [
"If you discount \"slosh\", the coffee will peak opposite the direction of acceleration. When you hit the accelerator the coffee pools at 6 o'clock, when you corner at 3:00 or 9:00, when you brake at 12:00. So you really want to choose a point between these that is least likely to be opposite the direction of accel... | [
"If you discount \"slosh\", the coffee will peak opposite the direction of acceleration. When you hit the accelerator the coffee pools at 6 o'clock, when you corner at 3:00 or 9:00, when you brake at 12:00. So you really want to choose a point between these that is least likely to be opposite the direction of accel... | [
"I think upwards would be best."
] |
[
"When life expectancy was 30, did people die of 'natural causes' or did they all die horribly from disease?"
] | [
false
] | I'm curious as to how people actually passed away at this age and what was the cause. Was lack of health and hygiene enough for the body to wear away faster, or did they all get diseases and pass away in sickness? | [
"A life expectancy of 30 doesn't mean that most people died around age 30.",
"The reason for shockingly low life expectancy statistics for most of our history is that there was a high infant and early childhood mortality rate. You were in fact more likely to die as a infant or young child; otherwise, if you survi... | [
"The numbers of people living into their 80's and 90's is statistically smaller until the 20th century."
] | [
"The numbers of people living into their 80's and 90's is statistically smaller until the 20th century."
] |
[
"Where are bananas' seeds contained?"
] | [
false
] | Most fruits, like watermelons, apples, and grapes, have easy-to-spot seeds, but I've never noticed any seeds contained in bananas. Are the ones we eat genetically modified to contain no seeds or are the seeds located someplace other than inside the peels? | [
"They don't have any. They're all cloned (split from a tree and replanted) from a single mutation, which is why bananas are so prone to disease. We lost one species, the ",
"Gros Michal",
", to disease (not entirely lost, but the disease was widespread enough to prevent the economic distribution) already. ",
... | [
"Here's a link to a recent SciShow video which is basically this above comment in video form, with a bit of extra trivia. And theme music.",
"https://www.youtube.com/watch?v=ex0URF-hWj4"
] | [
"Bananas are not \"genetically\" modified in the sense that people talk about \"genetically modified organisms\" or GMO.",
"All agricultural crops, including bananas, are technically genetically modified from their ancestral counterparts through selective breeding. However, the definition of GMO is that some form... |
[
"In the last 5-10 years, there’s been tremendous efforts made by many of the first world countries to curb carbon emissions. Have we made a dent?"
] | [
false
] | Where do we stand on present day global carbon emissions vs say 10-20 years ago? | [
"The ordering of that stacked graph there is unfortunate, because it hides the decreases in US/EU because they're stacked on top of \"rest of world\" which has been going up.",
"In other words, industrialized nations have been making progress, but it's overshadowed by emerging economies. On the other hand, India ... | [
"The ordering of that stacked graph there is unfortunate, because it hides the decreases in US/EU because they're stacked on top of \"rest of world\" which has been going up.",
"In other words, industrialized nations have been making progress, but it's overshadowed by emerging economies. On the other hand, India ... | [
"Having said that, is there an opportunity for new emerging economies to leap-frog straight to the greener technologies in their industrialisation?",
"A Green Leap Forward, so to speak?"
] |
[
"Why do house cats have slit pupils but big cats (lions, tigers, cheetahs, etc) have round pupils?"
] | [
false
] | null | [
"Here",
" is a fun article about it. The summary is that pupil shape has a lot to do with your position in the food web as a predator or prey, and the mode of hunting a species employs.",
"From the article: If you have a vertical slit, you're very likely to be an ambush predator, says Banks. That's the kind of ... | [
"Great article. Also wroth adding this bit.",
"But that rule only holds if the animal is short, so its eyes aren't too high off the ground, Sprague says.\nAnd while a small pet cat has vertical slits, Sprague says, \"the larger predators, like lions and tigers, have round pupils.\"",
"Tigers are mostly ambush p... | [
"But for anyone wondering, cats are quite a distant relative to the wild cats, a dog is more closely related to wolf than a cat to a lion",
"Correct. In fact, the species ",
" includes wolves, dingoes and domestic dogs. They aren't just \"closely related\" to wolves -- they are the same species. (The subspecies... |
[
"Question About Non-Newtonian Fluids and States of Matter"
] | [
false
] | [deleted] | [
"1) First rule of science: never speak in absolutes. So I won't say that any fluid won't behave in a non-Newtonian regardless of the conditions. However, there is a reason that while they seem to behave similarly, water is Newtonian while oobleck is not. It all has to do with how the materials behave under flow. Oo... | [
"2) Knowing that a non-Newtonian fluid is something that has a shear-dependent viscosity, that means it's impossible to have a non-Newtonian gas. Viscosity is a measure of a material's resistance to deformation; since gases have no such resistance, they have no viscosity and therefore cannot be classified as Newton... | [
"That's what I get for typing this off the top of my head. Looks like you're absolutely right about gasses having viscosity. But I still don't think it's possible for a gas to behave like a non-Newtonian fluid since there are so few intermolecular interactions. If you know more about this, please tell. I'm curious ... |
[
"Millions of stars are in the area of a sky covered by a pin's head. How do radio astronomers know which radio waves are coming from which star when they point their radio telescopes to the sky?"
] | [
false
] | Shouldn't what they get be white noise? Radio waves from millions of stars at different points in space and time arriving together? | [
"Sadly we currently are not able to detect individual stars that far away. The farther we get outside our galaxy the harder it is to detect individual stars. There are certainly millions and billions of stars out there but we can only see a small fraction of them. We detect galaxies instead and estimate the number ... | [
"If you're a person? No. If you're struggling to observe a radio signal that's a million times weaker than a cell phone? Yes."
] | [
"Radio astronomer here! This really depends on several things. First of all, one big detail here is a radio telescope's resolution on the sky, as they are definitely not all created equal- one that I use is experimental at a low frequency range, for example, so we lack resolution more than the size of the full mo... |
[
"Is there a \"smallest\" divergent infinite series?"
] | [
false
] | So I've been thinking about this for a few hours now, and I was wondering whether there exists a "smallest" divergent infinite series. At first thought, I was leaning towards it being the harmonic series, but then I realized that the sum of inverse primes is "smaller" than the harmonic series (in the context of the direct comparison test), but also diverges to infinity. Is there a greatest lower bound of sorts for infinite series that diverge to infinity? I'm an undergraduate with a major in mathematics, so don't worry about being too technical. Edit: I mean divergent as in the sum tends to infinity, not that it oscillates like 1-1+1-1+... | [
"If you have two sequences f(n) and g(n) (where the nth term of the sequence is the sum of the first n terms in a given series), then one way to define \"divergence speed\" is to look at lim",
" f(n)/g(n). If it's zero, then f is \"slower\" than g, and if it's ∞ or -∞ then f is \"faster\". If it's anything else, ... | [
"No. Suppose there was some smallest divergent series, call it sum[f(x)]. The series sum[f(x)/2] will also diverge, but be \"smaller\"."
] | [
"This response should be higher. I think it's most likely what OP was asking about.",
"I'd add that rather than talk about one series diverging faster/slower than another, we're really talking about one function diverging faster/slower than another (the partial sums). One can then prove:",
"If f(x), g(x) are ... |
[
"Can you represent PI in a finite number of digits in any number system?"
] | [
false
] | From a computer science course I know that you cannot represent the number 1/10 in a binary number system. But you can do it in a decimal number system. Is there a system where you can represent PI in a finite amount of digits? | [
"Of course, we could always use base pi to represent numbers, with which pi has the trivial representation \"10\". But surely non-integer bases are not what you are talking about. (They're also a lot of trouble anyway. For instance, if the base is algebraic then some numbers can actually have infinitely many expans... | [
"I just wanted to quickly add a less technical summary of ",
"/u/Midtek",
"'s excellent answer.",
"An irrational number is one that can not be represented as a ratio of two integers. In any basis, you can always multiply and divide a finite expansion by a power of the base to represent it as a ratio of intege... | [
"There is a little bit more alebra involved to go from repeating rational decimal to fraction, but this proof works on any repeating rational decimal. We'll use 1/3 for this example.",
". ",
"X =0.33333... ",
". ",
"Multipy both sides by ten. ",
". ",
"10X =3.3333... ",
". ",
"Subtract these two equ... |
[
"Why is there no lag between video and sound on my portable Bluetooth speaker but every car I have been in with Bluetooth has noticeable lag between audio and video?"
] | [
false
] | null | [
"I mean using your cell phone and trying to watch YouTube or something"
] | [
"We can't really comment on anecdotes / isolated incidents without resorting to speculation which we try to avoid."
] | [
"I'm not really looking for speculation. I know there are different types/frequencies of Bluetooth and I was thinking more along the lines of perhaps they use a type in cars that is more prone to lagging behind the video for whatever reason."
] |
[
"Why do salt crystals form in almost perfect cubes?"
] | [
false
] | At the beginning of last summer I left a bottle with a salt and water substance out in the living room. when we came back from vacation the water was gone and in bottle salt crystals had formed. Now what I don't understand is how the crystals formed in almost perfect cubes. Shouldn't there just be a thick flat layer of salt at the bottom? | [
"Crystal shape is defined by the packing of the individual atoms/molecules that make up the substance the crystal is made of. Ice is made up of the packing of water molecules, rock salt is technically called ",
"halite",
" and is the results of close packing of sodium and chloride ions.",
"In the packing stru... | [
"I think you really have two separate questions here: why are salt crystals cubic, and why did my scenario result in fewer, macroscopically large crystals vs a flatter layer of many more finer crystals? ",
"I'll answer the latter question and leave the first one to someone else. Crystallization from solution en... | [
"Nucleation (crystals initially forming) require molecules to meet and collide. That is far more likely to happen at higher supersaturations (i.e. when there are a lot more of them).",
"When there is low supersaturation, molecules are likely to meet crystals that have already formed, not other molecules. Hence, g... |
[
"Is there a fundamental particle at every point in space?"
] | [
false
] | null | [
"Called virtual for a reason - they're fictitious representations of a more complicated underlying mathematical structure. It's somewhat misleading to believe that there actually ",
" little particles popping into and out of existence."
] | [
"Now i'm intrigued. I'll take whatever you can tell me about this.\nAlso, thanks for probably clicking on a negative comment and then even correcting me."
] | [
"In a \"pure physics\" sense, for most reasonable time scales, a point of space can be measured to have no object occupying it. For sufficiently short time scales, there is a corresponding uncertainty in the energy present in the system, and you can't be certain that there's nothing there. ",
"In our actual unive... |
[
"[Computing] Does streaming a YouTube video use the same amount of cell data as downloading the entire thing?"
] | [
false
] | Title. For example if I streamed a normal YouTube video, would I use more or less data streaming it compared to downloading it with say: YouTube Red? | [
"Streaming ",
" downloading. The term \"streaming\" refers to playing back a media file while it's downloading -- the same data has to to end up on your computer regardless of whether it's being written to a file or immediately played back and then discarded.",
"That said, each YouTube video is available in mu... | [
"I can field this one.",
"Youtube uses a form of network aware quality adaptation that will switch your stream to a lower bitrate stream in times of network congestion, to prevent client media players from buffering and interrupting playback.",
"So, the answer is that a stream in 1080p quality ",
" be the sam... | [
"No, answer the dern question. Is it more because of TCP overhead or less because of decreased bitrates during congestion?"
] |
[
"AskScience AMA Series: I am paleontologist Hans Sues, I study late Paleozoic and Mesozoic vertebrates. Ask Me Anything!"
] | [
false
] | Hi Reddit, I'm Dr. Hans Sues. I am a vertebrate paleontologist who is particularly interested in late Paleozoic and Mesozoic vertebrates. I first became interested in fossils when I was four years old and, as a high-school student, started collecting animal and plant fossils with a group of amateur collectors. Later I studied earth sciences and zoology and received my Ph.D. in biology. I have worked as a university professor and curator for many years. I am now Senior Scientist in the Department of Paleobiology at the Smithsonian's National Museum of Natural History. My field research has taken me to many countries around the world. I have done a lot of and a about fossils for general audiences. I look forward to talking with you! I will begin answering questions at 12 noon Eastern Time (16:00 UTC). Username: MESOZOICGUY | [
"Just got the most hilarious commentary with the lovely headline \"You are stupid - but Satan loves you\"",
"I quote:",
"\"Just seen you going to answer questions on Reddit about Palizoic and Mezosoic eras being what you claim are 65 to 540 million year ago.",
"You're obviously a simpleton but even so you may... | [
"The largest dinosaurs were longer than the largest mammal today, the Blue Whale. However, the Blue Whale attains much greater body weight and thus still is the largest backboned animal of all time."
] | [
"Do I assume correctly that you are talking about commercial fossil hunters? Academic paleontologists in North America are very divided on this. (European and Chinese researchers usually work with commercial and private collectors.) I know many commercial fossil collectors and welcome them as long as they abide by ... |
[
"If light is massless, how can it have energy and still follow E=MC^2?"
] | [
false
] | null | [
"E = mc",
" only applies for massive particles which are not moving. A photon is both massless and ",
" moving.",
"The full equation is:",
"E",
" = (pc)",
" + (mc",
")",
".",
"For a massless particle, m = 0.",
"So this simplifies to E = pc, where p is momentum."
] | [
"p = mv also does not apply to a photon, it is an approximate equation for the momentum of a slowly-moving, ",
" particle.",
"A photon has both p and E not equal to zero, but it has m = 0.",
"Also, aren't all particles moving unless they're at absolute zero?",
"If you have a massive particle all alone in sp... | [
"p = mv also does not apply to a photon, it is an approximate equation for the momentum of a slowly-moving, ",
" particle.",
"A photon has both p and E not equal to zero, but it has m = 0.",
"Also, aren't all particles moving unless they're at absolute zero?",
"If you have a massive particle all alone in sp... |
[
"Does acupuncture work?"
] | [
false
] | null | [
"You won't get anyone giving you medical advice here, but acupuncture is still controversial and most scientists will tell you it's no better than placebo. The problems associated with conducting acupuncture studies make the waters murkier too and there are many studies fraught with methodological inconsistencies a... | [
"most scientists will tell you it's no better than placebo",
"That's a funny turn of phrase, given that placebos themselves can be tested against each other and found to have variable levels of effect depending on things like color of pill / bottle, person who dispenses them, etc. And also that even when the sub... | [
"To piggy back off this comment, chiropractors lobbied for a licensing requirement under the pretense of quality control. It was never intended to be an endorsement of efficacy. The only area that chiropractic treatment has any efficacy is for lower back pain, and the results are no more impressive than standard PT... |
[
"Do the kinds of collisions created in supercolliders ever occur naturally?"
] | [
false
] | null | [
"Yes. There are extremely high energy cosmic ray collisions happening in the atmosphere right now."
] | [
"The most intense particle collision known to have occurred on Earth involved the so-called Oh-My-God particle at over 20 million times the energy in LHC collisions.",
"You're comparing a \"lab frame\" energy to a center-of-mass frame energy. The center-of-mass frame energy of the OMG particle colliding with a nu... | [
"Furthermore, these collisions are much higher energy than in the LHC, up to a million times higher, or more.",
"The LHC is the highest energy particle accelerator ever built by humans, but in comparison to naturally occurring collisions from cosmic sources, it's actually a pretty low energy beam."
] |
[
"When you eat something that is labeled as having a certain number of calories, what percentage of those calories does your body actually absorb, and how much is left in the excrement that is produced?"
] | [
false
] | I realize that the answer is probably based on a few variables, like what kind of food it is, and the metabolism of the person eating it. | [
"In his book ",
"\"Catching Fire\"",
", biological anthropologist Richard Wrangham has a very nice section on the measurement of food energy and how it's worked through the human body. ",
"As MarineBoy said, it's the science on the subject is pretty soft, but it does seem clear that the traditional method of... | [
"In his book ",
"\"Catching Fire\"",
", biological anthropologist Richard Wrangham has a very nice section on the measurement of food energy and how it's worked through the human body. ",
"As MarineBoy said, it's the science on the subject is pretty soft, but it does seem clear that the traditional method of... | [
"Here is a BBC documentary on the subject: ",
"http://www.youtube.com/watch?feature=player_embedded&v=rf_OWun4Y04"
] |
[
"Avagadro's constant. How'd they do that?"
] | [
false
] | I was always curious about how this number was calculated. What was the model of experiment(s) that determined it? A quick google search tells me it was related to charge and mass of the electron, but beyond that I wanted to know the particular methodology of the experiments that got it to within 5 or so sig figs. I work in a completely unrelated field, but my first major was chemistry and I was always curious, especially given the precision of the number and the time it was determined (no computers?!?). My educational background in relation to this question; I was a chemistry major at a decent science school in the US who dropped out senior year (p-chem got me). | [
"It wasn't determined ",
" early, it took well over half a century from Dalton proposing his theory of atoms until they actually got a handle on the scale of them. The first, very rough approximations were due to the kinetic theory of gases. Maxwell (one of the pioneers of that) in 1873 ",
"made the estimate",
... | [
"This was exactly what I wanted to hear. Thank you very much! The links to the literature I particularly appreciate."
] | [
"In addition to Platypuskeeper's excellent response, the first answer with some real accuracy (in terms of significant figures) did not come until Millikan determined the charge of the electron. The charge of a mole of electrons was known (the number of coulombs per mole) so this allowed the calculation of the numb... |
[
"How does polyethylene (both high and low density) crystallise?"
] | [
false
] | From what I've read, crystallisation plays a major role in the properties of polyethylene. However, I have been unable to find information about how these crystalline regions are formed. Even if you provide the name for the method of crystallisation, that would be much appreciated. Of course a full length answer would also be much appreciated. Thanks! | [
"Polymer crystals are rather different to other crystal structures.\nWhat you'll typically see is regions where the polymer chains are neatly \"stacked\", doubling back end to end. Between these \"crystal\" areas, you get more typical amorphous areas, where the chains are arranged randomly.",
"Basically, polymers... | [
"From my research, I have figured out that polymers have crystalline and amorphous areas, which is why they're semicrystalline. So I gather that the only reason why there are crystalline areas is because it is more stable for the polymer to be arranged that way?"
] | [
"A crystalline region occurs because there is enough of some given interaction in the polymer (van der waal forces, pi-pi stacking, hydrogen bonding etc) to overcome the strain energy of packing so neatly in a given area. However, as Devil noted above, this packing causes strain energy, which must be accounted for ... |
[
"After sunlight exposure in vacuum, does the ISS hull become charged due to the Photoelectric Effect? If so, does this create any technical problems?"
] | [
false
] | null | [
"ISS has a ",
"plasma contactor",
" to dissipate any charge built up on its structure:\n",
"http://science1.nasa.gov/science-news/science-at-nasa/2001/ast13nov_1sidebar/"
] | [
"It is really outstanding how many details have to be dealt with to make those missions possible. The technology employed to solve problems most of us would never think of blows my mind.",
"Thanks for your reply!"
] | [
"IMO, space agencies are the biggest hubs of human intelligence. These guys are hyper efficient problem solvers. It's my dream to one day write code for a space agency."
] |
[
"Why does flat carbonated water taste so bad?"
] | [
false
] | null | [
"There's carbonic acid from the carbonation in the water, which has a bitter flavor."
] | [
"I take it that this is the reason that fizzy water tastes different in the first place, too?"
] | [
"Pretty much. There might be some other things that are different. Maybe the carbon dioxide has a flavor."
] |
[
"Will keeping my room at a lower temperature (about 60 degrees F) increase my resting metabolic rate?"
] | [
false
] | null | [
"I read something in The 4 Hour Body (Tim Ferris), that suggested something along those lines. But he was looking at the thermic effect of being in a swimming pool. Since water is 25x (IIRC) more thermally conductive than air, you can sit in a pool for a an hour or two and get a similar effect. Or you could take... | [
"It has been going around for a couple years that drinking ice-cold water is another method to increase your body's metabolic rate.... slightly.",
"This Wall Street Journal article",
" references a this ",
"actual study",
" on the effects of drinking cold water:",
"Here is an excerpt of the article: ",
... | [
"I think I'll check that out at some point, appreciate it"
] |
[
"Does odor have mass?"
] | [
false
] | Or is odor just a property of mass? Could I physically measure odor and in what units? If I leave a place and my clothes smell like something from that place, is it because I am carrying the odor or small particles of the object that had an odor? | [
"When you smell something it is because airborne molecules have found their way to your olfactory receptors. You are smelling tiny little bits of whatever is producing the odor, sort of like a fine dust in the air. The mass of these particles will vary depending on chemical structure and how concentrated they are i... | [
"So when you notice foul smells, take care not to think about the tiny little bits of whatever that just went in your nose."
] | [
"Your nose is basically a particle detector. For something to have an odor, airborne particles have to reach the olfactory receptors in your nose.",
"Apparently there is a way of measuring odor strength quantitatively.",
"http://en.wikipedia.org/wiki/Odor#Measuring_odor_concentration",
"The aricle is also qui... |
[
"If I was to freeze water that contained a dangerous bacteria, such as a strain that caused dysentery, would it sterilize the water similar to boiling?"
] | [
false
] | In a controlled environment: the water is pure aside from the bacterial strain, placed into an ice cube tray, and frozen. Would it have any effect? If not: could the bacteria remain cryogenic? | [
"Bacteria can form cysts or endospores to endure unfavourable environments until conditions improve. While the freezing would undoubtedly kill many of the bacteria, it is not guaranteed to. Even autoclave sterilizers that use 121 degree celsius heat to kill bacteria are not 100% efficient in doing so, and while not... | [
"Related point: Sometimes it is a toxin (typically a protein) that the bacteria produces, not the bacteria itself, which causes negative symptoms. That's the case with staphylococcus aureus, which can cause food poisoning. If it's the toxin that is the problem, freezing won't have an impact as proteins are stable a... | [
"So labs can put the bacteria into a completely frozen state and thaw them without damage? Thank you for the answer, too."
] |
[
"Why does the Earth's crust have different densities? Like how is oceanic crust always more dense than continental crust? Is this a way to determine if a dead planet had an ocean or not?"
] | [
false
] | null | [
"Why does the Earth's crust have different densities? Like how is oceanic crust always more dense than continental crust?",
"Composition. ",
"Oceanic crust",
" is primarily ",
"mafic",
" igneous rock (i.e. basalt or gabbro) with an average density of 3.0 g/cm",
" ",
"Continental crust",
" is more va... | [
"Generally, melting point increases as a function of pressure, so as a rock gets deeper, it gets harder to melt the minerals that make up the rock. The melting at subduction zones is primarily from the addition of water, which lowers the melting point of minerals. The water is primarily released during dehydration ... | [
"Does compression due to water factor into this at all, or is it mostly related to those geological processes you mentioned?"
] |
[
"When an airlock is breached in outer space, what happens to the air that gets sucked into the vacuum?"
] | [
false
] | Let's say that a spaceship has a compromised airlock. The air is sucked out through the breach, and everyone onboard dies. What happens to the air that gets sucked out of the spaceship and into the vacuum? Does it disperse like dust? Does it stay in one place? Does it drift in one direction forever? | [
"Good point. If you hadn't included that, people never would have known that I was referring to currently understood science. :)"
] | [
"Suction is a macroscopic effect. Particles in an area are constantly moving in all directions, and this motion averages out under static conditions. When containment in space is lost, there is an unbalancing of particle motion at the barrier between the pressurized area and the unpressurized space. More particles ... | [
"Suction isn't a force. There are only four forces - EM, weak, strong, gravity.",
"Once the particles are in space, \"temperature\" is no longer a good descriptor of them because they aren't a coherent gas. They are individual particles flying in specific directions. Thus, the Joule-Thomson effect doesn't apply."... |
[
"Questions from 2nd Graders about Animals - Students posting from 3:30 - 4:30 EST"
] | [
false
] | Dear AskScience, First of all, thank you for once again interacting with my students and ! You're all my favorite people on the internet, and you always go above and beyond. I am currently working with a group of 2nd graders once a week during an afterschool program. We are working on a project to create a book about animals, in which each student will contribute a page. Each student has chosen an animal, examined a picture of it, and generated questions about that animal. They have made some predictions about their questions, and are now seeking answers. We have discussed several ways students can research the answers to their questions. One resource that isn’t often talked about is asking an expert. This is where you come in, AskScience! Our 2nd graders are very eager to learn and are excited about getting to ask scientists about the animals they have chosen. Some questions are more in-depth than others; as an expert, perhaps you might be able to supply them with some additional information, fun facts, or prompts that might lead them into asking deeper questions. On my end, I will be walking around monitoring responses, helping students to understand and respond to the answers, and generate new questions. When this is over, the students will be writing a few sentences about their animal, will find or draw some pictures, and will compose a page that will go into the final, published book. Please remember that these students are about 7 and 8 years old, so choosing appropriate language is important! I have absolute faith in the AskScience community. (I would ask if anyone has a potentially offensive/inappropriate username, they post on a throwaway. ) The students will post on a shared account: "2ndGrader". I will be posting on my own account. Hopefully everything will go smoothly! Again, thank you so much for being a wonderful community, and thank you to the individuals who are taking the time to respond to the children. If you have any questions, please feel free to PM me! | [
"We ask our users to help the moderating team keep this discussion friendly and age appropriate by judicious use of reporting and voting.",
"Remember to target your science-based answers to a 2nd grade level. Follow up questions or additional interesting information is encouraged, but top level is reserved for t... | [
"Hello Darrian!",
"1) Snakes hiss because they want to warn other animals to stay away from them! They don't want to get hurt, stepped on, or beaten up.",
"2) Some snakes will wag their tails because they are will use it as a warning call (rattlesnakes) or they may use the tail wag to distract their enemies ... | [
"I can help with the whisker question. Whiskers are just like regular hair, except they are thicker and connected to more nerves, which help animals feel through the whiskers. It's like how you can feel when someone moves their fingers through your hair, except much much more sensitive.",
"When cats, dogs, otte... |
[
"How and why does scratching relieve an itch?"
] | [
false
] | I'm talking about general itches which result from skin irritation, like a tickle or a mosquito bite. What I don't understand is how a sharp utensil like a fingernail can stop the itch, or at least offer brief relief until the itch returns. How is it that scratching has this effect? | [
"Not to hate, but: ",
"I'm not sure scientists consider it mundane. Scratching has a lot of negative consequences (it can be absolutely terrible for your skin), its a symptom of a lot of diseases, and it's a side effect of a lot of drugs. As a noxious stimulus, severe itching isn't a lot better than severe pain. ... | [
"Those are all very good points and a much more plausible explanation.",
"Today I learned to be less flippant with my comments on AskScience. "
] | [
"Coming from a medical student:",
"This was discussed in our neuroanatomy class, my teacher made it seem that scientists don't really know. I just tried looking on the internet further, found an article with this line: \"Currently, there is no proven hypothesis on the functional basis of scratching the kind of tr... |
[
"What causes a specific note to be produced when feedback is looped through an amplifier back to the pickup?"
] | [
false
] | Hey guys, I was playing my guitar today and I noticed when you crank the amplifier gain and have your volume at a reasonable setting, you generate a feedback loop. This isn't new but what I noticed was the note it produced, it was inline with the harmonic points of the string, and not the note of the open string itself. My previous physics knowledge taught me that a harmonic is a temporary node on the string, similar to a fret except that it isn't a physical node. When a harmonic is struck, the entire string has energy producing the wavelength but it is completely stationary at the node point. These nodes are perfect divisors of the entire length of the string, causing the frequency to multiply linearly (1st harmonic is the open string, 2nd harmonic is the string divided in half, 3rd is the quartered string and so on). What causes the string to produce a note that coincides with the harmonic points on the string, but without any nodes? As a footnote, if you have a guitar play the E harmonic on the A string (7th fret), it's an E5 apposed to the A3 you play with the open string. That E5 is the note my amplifier feeds back to my pickup, except there's no human interaction creating the note. And it isn't a harmonic played by the string. | [
"Yes that explains the feedback loop, but what determines the frequency the loop is producing? If I were to pluck the string that builds energy I get as I mentioned, an A3, or the 5th string I'd get just that, an A3. When frequency is resonating in the instrument it produces a completely different note. ",
"Edit:... | [
"image",
"If a string is vibrating at its fundamental frequency (say, 100 Hz), the entirety of the string is up, then down. This vibrational mode is easily excited by a sound source at that frequency, located 'above' the string in that image.",
"If the speaker instead produces a 200 Hz tone, this could potenti... | [
"The susceptibility of the string to excitation by a nearby speaker seems greatest at odd-numbered harmonics, since those involve unequal quantities of string moving towards and away from the speaker. Even-numbered harmonics have the same amount of string moving away/towards, which would seem to lower the response... |
[
"How does a sheet of laminated paper or thin metal make a wobble-wobble sound when you...wobble it?"
] | [
false
] | I'm talking about this kind of thing: | [
"This is caused by a process called buckling (in this case: elastic buckling). When you put lengthwise force, e.g. bending stress, on a thin piece of material it will start to yield (strain) a little bit as you increase the force. At some point, the material will not be able to withstand the force anymore and yield... | [
"When the board is flexed, there is some warping that resists deformation, until it suddenly plops through. According to \"Musical Instrument Design: Practical Information for Instrument Making\", this causes vibrations in the sheet that make the wobbling sound.\n",
"https://books.google.se/books?id=CuHi9edzELEC&... | [
"Wouldn't it be the same principle as a regular string? Only because it's a planar object and the frequency of the wave propagated by stress in the material differs depending on which portion of the sheet you're bending it would produce several soundwaves at once?"
] |
[
"Is it possible for a planet to rotate about two axis' at the same time?"
] | [
false
] | With the Earth, the North and South poles are essential frozen because they aren't as exposed to the sun as much as the equator. Is it possible for a planet to rotate about a second axis, essentially constantly changing which poles are frozen or a tropical paradise? | [
"In 3D space, rotations on any number of axes can be reduced to rotation about one axis - so any planet that rotates about two axes is merely rotating about one axis that's the sum of the two rotations."
] | [
"That's actually really simple to understand.",
"\nI drew you a little picture, just picture how the ball would spin if he would spin on both shown axes.",
"http://m.imgur.com/odaLB4o"
] | [
"That occurs because of the ",
"tennis racket theorem",
", which applies to objects with three different moments of inertia - like the T handle in the video you linked to. For a cube or sphere, this would not occur.",
"It's really cool because it was only discovered in 1985 - it's a phenomenon that wasn't rea... |
[
"Why does matter travel through time in only one direction?"
] | [
false
] | Or is that a misconception based on our perception of reality? EDIT: Expanding slightly... Matter seems to travel in the other three large dimensions relatively freely. Why should time be any different? | [
"We don't know."
] | [
"You are making it seem as though time is a complete illusion. We might not perceive objective reality but that doesn't mean our perception isn't veridical to some degree. It's the only mode of perception that means anything to us, so it means ",
" to us. "
] | [
"You are making it seem as though time is a complete illusion. We might not perceive objective reality but that doesn't mean our perception isn't veridical to some degree. It's the only mode of perception that means anything to us, so it means ",
" to us. "
] |
[
"Why don't non-spiraling galaxies collapse on themselves?"
] | [
false
] | Since there's no rotating motion, there isn't anything to counteract the average gravity, right? | [
"When you see the word 'spiral' in order to describe a galaxy, it simply denotes how the galaxy is visually structured in order to make it easier to classify all the different types out there. The lack of the term doesn't imply the galaxy isn't rotating, because they all are.",
"Hope that helps."
] | [
"Elliptical galaxies have stars with more randomly oriented velocities. Their stars still have a \"standard deviation\" of velocities (also called a velocity dispersion) that is comparable to the rotational velocities of stars in elliptical. So basically you have a lot of stars in lots of different orbits rather ... | [
"Elliptical galaxies don't have very much bulk rotation."
] |
[
"Will you lose your cigarette addiction if you're in a coma for a long time?"
] | [
false
] | null | [
"It sounds like what OPs really wanted to know was \"is there anything about a coma that would leave addictions in their place or slow down the withdrawal process\". Do we know anything about that?"
] | [
"It sounds like what OPs really wanted to know was \"is there anything about a coma that would leave addictions in their place or slow down the withdrawal process\". Do we know anything about that?"
] | [
"Not solid science but damn near relevant experience."
] |
[
"Would it be possible to design a spring with variable stiffness depending on an applied electrical current?"
] | [
false
] | Say I want to design a constant force translational spring with a decent amount of play. For a constant force Fc, I guess the spring would have to obey Hooke's law F = kx, where k would equal to Fc/x. Are there any materials where one could vary the stiffness using a current, or otherwise achieve a similar result? Current designs for constant force springs seem to have very little play. I could use an actuator but want to keep it as light as possible. | [
"Not quite what you're looking for, but there are magnetorheological dampers, which are hydraulic pistons filled with a ferrous fluid. An electrical current is applied to an electromagnet- usually just a spiral of copper wire inside the piston, and this causes the ferrous particles in the fluid to align, thereby in... | [
"There are actually magnetorheological elastomers, where the iron particles are embedded in a rubber or urethane which accomplish stiffness modification with magnetic field similar to MR dampers: ",
"https://en.m.wikipedia.org/wiki/Magnetorheological_elastomer"
] | [
"So when the current is turned on, my piston would have much larger stiffness, and when turned off the fluid inside would relax making it less stiff?",
"Sounds familiar"
] |
[
"Quantum superposition"
] | [
false
] | First time asker, and will most likely have to rephrase or explain this more deeply, since i don't understand the subject as well as i would like to, but here goes. In quantum superposition is a particle which can be observed as two particles actually representing the opportunities that particle has at that moment, and does the particle "think" that it is not being observed so it shows it's potential locations. Or are locations even meaningful in quantum physics? Like i said the question isn't very clear, but i hope someone could shed some light upon at least one of the things i was asking. | [
"After you test the particle, the experimenter-particle system is in a superposition of \"experimenter sees particle in A\" and \"experimenter sees particle in B\". You only experience one branch of the superposition though; some people think this implies that an \"alternate universe\" is created where you experien... | [
"That's not an accurate statement of the many-worlds interpretation. The universe ",
" have already decided which state the particle is going to be in; through Bell's theorem, you can prove that such a universe would not behave like ours does."
] | [
"That's not an accurate statement of the many-worlds interpretation. The universe ",
" have already decided which state the particle is going to be in; through Bell's theorem, you can prove that such a universe would not behave like ours does."
] |
[
"What defines a sound's \"texture\"? Like how some guitars sound softer, some rougher, etc."
] | [
false
] | I understand that sound waves have frequencies and amplitudes, but I don't understand why two sounds that have the same frequencies and amplitudes can make different noises. Another example is peoples' voices. Why does my voice sound different than my friend's voice and also different than my dad's voice, etc. There are so many people in the world that if freq. and amp. are the only defining aspects of a sound, people would have to have very similar voices. I hope I'm making this question understandable. Thanks so much for any help. The real internet is too hard for me. | [
"As I don't know too much about physics, I can't go too much in to the nitty gritty of it, but what you are referring to is called \"Timbre\" (pronounced TAM-ber). This is the quality of a sound separated from it's pitch and loudness. I can play the same pitch on a piano as on a guitar at the same volume but they w... | [
"See this image here",
". Different instruments can have the same volume (amplitide) and same pitch (frequency), but completely different sound.",
"It's because they have ",
"different waveforms",
". Thinmk about them as having different shaped waves.",
"(Ironically, all waves can be reduced to a sum of d... | [
"This is the correct answer. To OP, A simple example of a Timbre is a sine-wave vs. a square wave (both can have the same frequency and amplitude). Now you can imagine any type of shape that repeats at any frequency, and have a certain volume (amplitude). That's why people voices are different. and that why 'Octate... |
[
"How does soap work to get rid of odors and bacteria?"
] | [
false
] | [deleted] | [
"Let's say you're washing your hands in two hypothetical scenarios: 1) You just ate an orange and don't want your fingers to smell like a fruit 2) You haven't bathed or washed your hands in days and now they're starting to smell.",
"In the first case, you could argue that some of the smell is coming from fat solu... | [
"Soap is a surfactant, so the most basic explanation as you said is that soap molecules have two ends, a hydrophilic (water loving) end which attaches to water molecules, and a hydrophilic (water hating) end that attaches to oils and dirt. When you wash your hands, one end of the soap molecules attaches to the dirt... | [
"Here's an illustration: ",
"https://www.sarthaks.com/21470/explain-the-cleaning-action-of-shop",
"Basically the hydrocarbon tail of soap molecles will stick to the surface of dirt or bacteria membrane pulling it away from the skin. In presence of water, the molecules form micelle trapping the dirt in the core ... |
[
"Is using anti-bacterial hand sanitizer as healthy as actually washing your hands?"
] | [
false
] | [deleted] | [
"It depends strongly on your situation.",
"In everyday life there is no reason to use hand sanitizer because washing your hands is better for your health. First of all, what you want to remove is potentially harmful bacteria and viruses. Washing your hands properly does this. You don't even need to get rid of ALL... | [
"Overtime, the bacteria may become resistant to sanitizers. Especially the non-alcohol ones. Also, you don't flush the debris away. You rub the dirt into your hand. "
] | [
"At least for anti-bacterial soap, there seems to be ",
"no documented health benefits",
" over normal hand soap..."
] |
[
"Is it possible for microorganisms to leave our planet without aid of rockets or other advanced mechanics?"
] | [
false
] | I realize that weather balloons can go fairly high, but not enough to escape the gravity well. I also have heard theories that some bacteria on earth may have come from asteroids/other planets. Is this only possible as a result of massive impacts/asteroids/planetary impacts? Removing rockets from the equation, would it be possible for small enough organisms, spores maybe, to escape the atmosphere? | [
"Ejecta from large bolide impacts can escape the Earth's gravitational influence. Also, we know that extremely hardy life exists on our own planet- they're known as ",
"extremophiles",
" and they can survive under extreme physical and chemical conditions. The combination of these two things have lead people to ... | [
"Panspermia: ",
"http://www.spaceref.com/news/viewpr.html?pid=7089",
"Mushrooms spores are < 5 microns in size in some species, and could survive in space according to some researchers. Not fact, but worth further investigation. Fungi are very important to breaking down raw materials to make them ready for pl... | [
"It is ",
" easy for impact ejecta to escape Earth's gravity; there are no cases where a volcano has erupted material at greater than escape velocity. Meteorites have been ejected from the Moon and Mars by low angle impacts on these largely airless, low-gravity, worlds. It would require a very large impact to ej... |
[
"If someone has a fully sealed iris (like the One that recently reached front page), why can't doctors simply cut a pupil into the iris?"
] | [
false
] | null | [
"A pupil is not the lack of iris. If you were born with no lips they would not appear by cutting the area directly above and below the mouth hole. It would bleed and begin the normal healing process. This would work out far worse in the situation involving an eye."
] | [
"The iris wouldn't function the way it's meant to (constriction and relaxation) so the person would likely have extreme sensitivity to light. This is one among many problems that could result: blocking of the drainage system of the eye --> increasing eye pressure resulting in damage to the optic nerve (glaucoma). A... | [
"Could I have a link to that post?"
] |
[
"Why do we cry?"
] | [
false
] | I'm talking about tears due to emotion, not normal physiological lubrication or irritant removal. Evolutionarily, it seem like a terrible idea to have a stress response that includes obscuring your vision and making your nose run. What advantages could crying confer to a species that makes it so widespread in humans? | [
"Beware assuming your cultural norms apply to humanity as a whole."
] | [
"It's an open question. ",
"Wikipedia lists several working theories.",
" Note that the last one specifically addresses your 'obscured vision' dilemma, in that by signaling submission by outwardly displaying a handicap which indicates that your defenses are lowered, others in a group might be more willing to ... | [
"Humans are an extremely social species. You have to consider many traits with regard to how well they enhance fitness in a group. I presume crying would alert other people to know something is wrong."
] |
[
"What colour was the cosmic background radiation?"
] | [
false
] | More importantly, is it more likely that it was a long wavelength colour, or a low one? (My understanding is that over time, the wavelength of the light from the cosmic background radiation got longer and longer, until it reached infra red, sorry if I'm misunderstood.) | [
"At recombination (when the universe became clear), the temperature was around 4000 kelvin, so it was glowing red."
] | [
"No leave it up."
] | [
"Thank you! Now that I have my answer, do I just delete this, or do I leave it up for anyone else curious?"
] |
[
"Can cats survive their own terminal velocity?"
] | [
false
] | I heard this was true, but I'm not sure. If this is true could a cat survive a fall from an airplane or, if it were properly insulated from cold and low pressure, space? | [
"Yes"
] | [
"great graph"
] | [
"Disregarding the cat's survival; terminal velocity is terminal velocity, whether you fall from the minimum point to reach it or the outer edge of space just means you have a longer fall till you reach the ground at the same velocity."
] |
[
"Does tanning decrease vitamin D intake?"
] | [
false
] | Whenever someone is regularly outside, do they absorb less vitamin D because of the melanin their body produces? Do "whiter" parts of a person's body take in more vitamin D than "tanner" parts? | [
"Melanin does block vitamin D production in the skin. It's a problem for dark skinned people in northern climates. For light skinned people, getting a tan decreases production, but you get something like 10,000 or 20,000 units per hour when sunbathing, so it doesn't take much exposure to get what you need. "
] | [
"How much is one unit? What kind of number is \"daily recommended dosage\"? (i realize vitamin time spans are probably larger than days, maybe asking about monthly recommended dosage makes more sense?)"
] | [
"Vitamin D isn't absorbed through the skin. For vitamin D3, specifically, UV light converts 7-dehydrocholesterol into vitamin D3. VD3 is then hydroxylated in the liver, then kidneys, through activating pathways to make the active form (1, 25, dihydroxy vitamin D3). "
] |
[
"Why does it take so much longer to tune to a digital channel than an analog one?"
] | [
false
] | null | [
"It doesn't take longer to tune in, however it does tak longer to display an image. Digital image streams are generally 'differential' streams, that is, since each frame is so similar to the one before it, it's easier to compress and transmit only the differences between each frame. Once in a while, a 'key frame' ... | [
"The main reason is that digital channels contain compressed information, and proper decompression is only possible from certain points. ",
"Video contains key frames which encode the whole picture, and other frames which only encode changes between frames. There, proper decompression must start at a key frame. I... | [
"The problem is that digital channels require you to \"tune\" to a station. To \"preload\" adjacent stations, there would have to be two separate tuners. Also, there are bandwidth restrictions to consider, many digital channels take up the entire available bandwidth to display, whereas web pages, once loaded, gener... |
[
"What do you call the protein on the surface of CD4+ cells that allows other cells to know ita infected?"
] | [
false
] | When HIV goes away from the cell it manifested,it takes with it the host cell membrane(cytoplasm),which helps the bioinformatics(protein molecules of HIV) to hide and not be detected by the system. Is there not any protein/enzyme on the surface of the cytoplasm that shows that it was once infected? And that the HIV virus is just using it as a front line to hide itself? What do you call the protein on the surface of CD4+ cells that allows other cells to know its infected?Is it MHC 2? | [
"cell membrane(cytoplasm),which helps the bioinformatics(protein molecules of HIV)",
"I'm very confused. The cytoplasm is the inside of the cell, the cell membrane is the membrane. Bioinformatics is a field of research.",
"I'll let an immunologist respond to the rest."
] | [
"Your question is a bit confused so not quite sure what you are asking, but I think the answer to your final question there is T cell receptors. Antigen-presenting cells take up foreign cells/viruses and present peptides from those pathogens on the MHC 2 receptors on their cell membrane. The CD4 receptor and the T... | [
"As other answers mentioned, you have a lot of words getting used incorrectly in your post. However, in a more general sense, the answer is MHC I. MHC I is responsible for the presentation of antigens within the cell by nearly all the cells in the body -- MHC II is primarily used by professional antigen presenting ... |
[
"How does NASA \"download\" images from Hubble?"
] | [
false
] | I mean, what's the mechanism for some technician at NASA to connect to Hubble, and download the images? How are they stored on Hubble? As computer image files (jpg, tiff etc) or some other way? How big are the files? How fast is the transmission rate between Hubble and Earth? I've always been fascinated by this sort of stuff | [
"After some reading looks like they are microwaved from the hubble to the TDRSS communication sattilites, then that is microwaved to the White Sands Antennae Array",
"Here is some info from ",
"Nasa.gov"
] | [
"While I don't know much about the hubble, someone in my lab was working on a ",
"GIS",
", and he briefly explained how modern Earth facing satellites work. In other words, this is second hand.",
"The key problem is that they capture data orders of magnitude faster than they can ever hope to transmit it. Many... | [
"This is quite correct. Hubble was designed to use the TDRS relays to get data to the ground, so it knows (i.e. on-board equipment was designed for this specific purpose) how to interact with the TDRS constellation. ",
"The other half of the equation is how the data is interpreted when it reaches the ground sta... |
[
"What's actually going on, in physics terms, in Bose- Einstein Condensate?"
] | [
false
] | I asked my HS teacher this question today and he seemed dumbfounded, so here I am guys. See title. I know all about absolute zero, motion ceasing, bosons in the lowest quantum state, and all, but I was curious as to what really happens. | [
"I know all about absolute zero, motion ceasing,",
"First, let's be quite clear here, BEC does ",
" involve motion ceasing and does ",
" involve absolute zero. Both of these are impossible.",
"The real phenomenon at the heart of BEC is...well, exactly what you then said. The bosons all enter the lowest quan... | [
"Just curious if there were any more complexities by chance. And for the record, I realized that right as I typed it that someone would point that out. Thanks though!"
] | [
"There are many complexities. The exact math and physics behind it is nontrivial. ",
"Here's a video",
" that may be of some help. "
] |
[
"'Dropping' things from orbit."
] | [
false
] | So, I've been having vivid dreams and thinking in vectors again (uh oh!). I hear people talk about the concept of 'dropping' things from orbit, usually to use as weapons. The more I think about it, the lowest-energy way to 'drop' something from LEO onto the surface would be to propel it from your current trajectory, no? It seems that aiming 'down' at the target would actually take more energy, since as your altitude drops, the projectile would 'get ahead' of the target. Can someone draw some pictures? Would a small mass-driver-type weapon need some base amount of propulsion and guidance to effectively be used from LEO? Would it make more sense to drop from a geosynchronous orbit (much higher altitude, but at least the surface below is 'steady')? Overall, what are the implications for hypothetical orbital weapons platforms? What would happen if I was in LEO and tossed a baseball (or shot a gun) backwards? What about 'Earthwards'? Would either projectile hit the earth (assuming no atmosphere)? If so, which projectile would get to the ground first? | [
"You're right. If you want to blow up something directly below you, the lowest energy way to do that would be to fire the projectile almost exactly against your orbital velocity (you'll want to account for how much the earth rotates during the time it takes for your bomb to fall.)",
"If you throw an object down ... | [
"From geosynchronous orbit, the problem of missing the Earth is worse than LEO, not better. If you gain an inward velocity, you don't maintain the same angular frequency. It's not as if you spiral into the planet.",
"What you are saying about propellant makes sense. ",
"Regarding de-orbiting a 1 kg object, I... | [
"(neglecting the atmosphere)",
"Incidentally, wouldn't this path send you through more of the atmosphere than any other possible route?"
] |
[
"What is it that prevents \"Irish cream\" from going bad? Why doesn't it need to be refrigerated?"
] | [
false
] | [deleted] | [
"It's the alcohol. Most microbes cannot tolerate an alcoholic enviroment. As a rule of thumb, it takes upward of 60% alcohol to reliably kill the things off, but even the lower 15-20% content in Irish creme will inhibit the growth of most of them.",
"There are two main reasons it doesn't curdle. First, fat inhibi... | [
"Baileys was one example, there are plenty of Irish creams out there. And I'm asking more about the chemical process: what is it that stops a product that usually degrades fairly quickly even while refrigerated from going bad at room temperature for years?"
] | [
"Baileys shelf life",
"Baileys is the only cream liqueur that guarantees its taste for 2 years from the day it was made, opened or unopened, stored in the fridge or not when stored away from direct sunlight at a temperature range of 0-25 degrees centigrade.",
"One of the keys to achieving this 2 year shelf-life... |
[
"what is the chemical makeup of a tomato?"
] | [
false
] | [deleted] | [
"There are literally thousands of chemicals in a tomato, just like any other living organism. The main ones you'll find are water, cellulose, various sugars, and probably citric and malic acids. "
] | [
"I don't know about all the active chemicals, but tomatoes have a temperature sensitive chemical called \"z-3-dexanol\". When tomatoes are refrigerated that chemical changes and so, makes the tomato taste different. (ref: Alton Brown, Good Eats)."
] | [
"It's actually (Z)-3-hexenal, and I've never heard any credible reason why cold temperatures would damage it. The only ",
"reference",
" I could find with respect to the cold thing talks about the effect of temperature on an enzymatic system that produces the aroma compounds upon exposure of the tomato flesh t... |
[
"My math teacher in 5th grade told us this formula to find out if a number is prime. I still use it today, but never found it mentioned/proved in mainstream books. Anyone know if it works for all prime numbers?"
] | [
false
] | [deleted] | [
"This doesn't work, but it's interesting to examine why it appears to work for a few cases more closely. ",
"x",
" - 1 = (x + 1)(x - 1)",
"If x is prime, and x does not equal 2, then (x + 1) and (x - 1) are both even numbers. Let (x - 1) = 2k, then the test is that if k(k+1)/6 is a whole number, then x=2k+1 i... | [
"x=25"
] | [
"I don't, it's hard to follow. Here's a better one, made ",
" I had caffeine.",
"24 has no prime factors other than 2 or 3. If (x+1)(x-1)/24 is a whole number, then (x+1)(x-1) must be evenly divisible by 2 and 3. ",
"Assume that (x+1)(x-1) is evenly divisible by 24.",
"It is clear that (x-1), x, (x+1) are c... |
[
"Do bugs sleep? If not, what are they doing when they're not around?"
] | [
false
] | You get day bugs, night bugs, some that come out during the morning and some in the evening. But what do they do in their (for lack of a better word) downtime? Bees during the night, moths during the day, that sort of thing. | [
"Yes, bugs do sleep. They have a central nervous system which presence seems to indicate the need for sleep. Studies have shown that insects that are forced to stay active during the normal down-time will rest when they are normally active.",
" This would indicate that their down-time is for a sleep-like rest, an... | [
"Thanks, I just learned a new term -- stealth dining!"
] | [
"Are there any animals that don't require sleep though ?"
] |
[
"Why do we develop dominance in a certain arm/leg, and are we the only species to do so?"
] | [
false
] | null | [
"Which is why when people ask me what my dominant hand is, I simply state, \"Polar bear.\""
] | [
"There isn't any proven theories about right or left dominance, but its speculated that its simply a stronger signal to one side of the body. its an interesting study as to if nature or nurture is the root of which hand or side a person will prefer. Nurture would be supported because of how many people are 'right-h... | [
"There's a tendency to favor one side among at least some other animals. Parrots appear to prefer to use one foot to pick up food, for example:",
"http://en.wikipedia.org/wiki/Laterality#Laterality_in_other_animals"
] |
[
"What's the big deal with magnets? Magnetism, more specifically"
] | [
false
] | null | [
"Richard Feynman on why he can't explain ",
" magnets work.",
"He says he can't explain ",
" magnets work. Not how. "
] | [
"Richard Feynman on why he can't explain how magnets work."
] | [
"Still worth watching. One upvote each."
] |
[
"What would happen to the string in this scenario?"
] | [
false
] | Two objects, A and B, of equal mass are at rest in space and connected by a 10 meter cotton thread. Object A begins accelerating at 500 m/s². Assuming that this is not an ideal string, what happens to the string? My expectation is I haven't provided enough information for a satisfactorily scientific answer, but I'm wondering what specifically I'm missing in my understanding of this situation. If possible, please suppose real world values, i.e., "it's a cotton string, so it has a fairly small breaking point of only XX Newtons. When the tension exceeds XX, the string will break," in a response. | [
"Wow, a downvote and no replies? Did I do something wrong? I tried googling this last night for over an hour, and it's ",
" hard to find information about a string physics between two objects without gravity being a factor. I found many results for pendulum problems and ",
" results about guitar strings, but no... | [
"500 m/s2 would snap the cotton thread."
] | [
"Thank you! I had thought so, but I wasn't sure how to formulate it exactly. My thought process goes that if it takes 50 Newtons of force to break the cotton thread, it would only take a mass of .1 kg for Object A with the given acceleration for the cotton thread to break. So it would seem that if the mass of objec... |
[
"Do we have the technology to 'subtract' sound? Like take vocals out of a song for example."
] | [
false
] | Suppose a band was playing. Suppose that microphone A was setup to record the total sound that the band was producing. At the same time, microphone B was setup to record only the vocals (maybe via split mic lines and a very elaborate sound proof booth setup). Is it possible to take these 2 recordings and get only the sound produced by the instruments? | [
"I recently answered a very similar question ",
"here",
"."
] | [
"Can I ask a somewhat technical question?",
"You say you use independent component analysis for separating the components of the sound. In this field, what are the advantages of ICA over non-negative matrix factorisation?",
"Most of the astrophysical problems of this ilk are better solved by NMF, as far as I kn... | [
"I'm not very familiar with NMF methods. Do you just use singular value decomposition or a similar linear algebra process to solve for a mixing matrix in that method?"
] |
[
"How come when you fall asleep or your eyes are closed for a while in direct sunlight and then you open them again you see blue for a while?"
] | [
false
] | I have always wondered this, and today i thought, why not ask reddit? So why do you see blue for a while after your eyes are closed in direct sunlight for a while? Thanks askscience! | [
"i always figured it was because of your eyes filtering out red to compensate for the red sunlight coming through the blood in your eyelids, when the red is taken away(when you open your eyes) everything seems blue by comparison. ",
"You can simulate it if you look at ",
"this",
" for about 30 sec, and then l... | [
"Rhodopsin has a purple pigmentation and is responsible for our ability to see in the dark (whatever little extent that is). So, eyes are close = increased levels of rhodopsin. When you open your eyes, rhodopsin photobleaches if exposed to bright light. Most people experience a white flash. You may see blue partial... | [
"To provide a little more background of what you added....",
"The example you are portraying here is color burn, or ",
"'after-image.'",
" The prevailing theory is it has to do with neural adaption, or compensation. ",
"I still stand my ground based on the physiology of rhodopsin. ",
"EDIT: I originally t... |
[
"What makes outside air smell fresh?"
] | [
false
] | What is it that makes the air from outside feel so refreshing when I let it mix with the “neutral” feeling air of my bedroom? Is there something in the air outside that somehow dissipates when it's enclosed somewhere for a while? Is something psychological going on? What's up with that good-feeling air? | [
"Another aspect of \"freshness\" concerns the smells and gasses that are given off by interior furnishings, pets and sweaty people. The longer a room is sealed off, the greater the concentrations of these gasses. Opening a window flushes out these unpleasant smells."
] | [
"To add, about outside air having a 'good-feeling' property: the brain has a disproportionate demand for oxygen. (Brain weighs about 2% of the body, but consumes 20% of oxygen) So it can be said that the brain is also sensitive to changes in oxygen content in the air we breathe in. More oxygen makes one feel fresh ... | [
"To add, about outside air having a 'good-feeling' property: the brain has a disproportionate demand for oxygen. (Brain weighs about 2% of the body, but consumes 20% of oxygen) So it can be said that the brain is also sensitive to changes in oxygen content in the air we breathe in. More oxygen makes one feel fresh ... |
[
"Where do autistic people derive their of morality from? If the ability to feel 'empathy' is not core to our morality, how does the brain derive morals and sense of social justice?"
] | [
false
] | Edit: Adding more info to clarify the intent behind this question. I am reading the book 'Tell Tale Brain' by V S Ramachandran. He has a chapter dedicated to Autism, and he stresses that they sometimes have a stronger sense of morality that the neurotypical people. I stressed empathy, 'cos my layman's understanding says our mirror neurons gives us the ability to empathize, which is probably sub-par or insufficient in autistic individuals. | [
"What an excellent and thought provoking question. For starters autism spectrum covers a wide range of poorly understood disorders so there isn't a one-size-fits-all answer. ",
"But here is one answer; \"But people with autism may perceive morality differently than normally functioning people because they focus ... | [
"I suffer from aspergers, a mild kind of autism. I feel empathy, i have high moral standards and social knowledge. I just cant show it very well. The fact that i cant show my feelings, often lead to depression and anxiety.",
"Your question is kind of a false assumption. Maybe you should try and rephrase it."
] | [
"While Autistic individuals may not understand emotions in others to certain degrees I'm sure they understand pain in others.",
"Wouldn't that perhaps underpin a restricted form of empathy? They might not understand that they've upset you or how you were feeling but they would understand if you were injured?",
... |
[
"How do we know chemical reactions doesn't react with air?"
] | [
false
] | for example A+B-> C How do we know there isn't air involved in A+B? Don't you need to have a vacuüm to be 100% sure there is no air involved? | [
"We can pretty easily see that oxygen isn't in the products if we can see what atoms make up both the reactants and products, and so for that we can rule out air involvement. If we are a little unsure we can do isotopic studies to actively watch the movement of atoms to confirm.",
"However, your question gets to... | [
"To add: many reactions which are known to react with air (usually the oxygen content) are carried out under the atmosphere of an inert gas, usually nitrogen gas. This is done by flushing the apparatus with nitrogen gas and keeping the experiment closed to prevent re-entry of oxygen into the apparatus.",
"EDIT: I... | [
"FWIW, I believe sparge refers to a liquid. Nitrogen \"purge\" seems more appropriate here"
] |
[
"What is the 'bump' at rotation of a commercial airplane?"
] | [
false
] | At rotation (when an airliner's nose first rises up, during takeoff), there is usually a noticeable 'thump' or 'bump', in terms of both sound and physical sensation. Given that the plane is becoming airborne at that point (i.e., applying increasingly less weight on the wheels and ground), what causes this 'bump'? | [
"The thumping sound happens when the wheels hit minimum suspension. ",
"When the plane is on the ground, the wheels are closer to the fuselage because the plane is really heavy, and because of the suspension. ",
"When the plane generates enough lift to get off the ground, the wheels get farther from the fusela... | [
"While I know that landing gear retraction occurs very soon after takeoff (and much sooner than most people realize), this is literally at rotation - as the nose begins rising but the rear wheels are still on (or just lifting from) the ground. "
] | [
"The suspension hits the end of its travel ",
" when the wheels break contact with the pavement. There's a lot of pressure in those shock struts, so it can make quite a bump. Bear in mind that you don't have any way of knowing when the wheels break contact, because you obviously can't see them.",
"The CRJ-200's... |
[
"Why do many physicists seem to assume the existence of an elegant, simple, Theory of Everything? Is there evidence for the possible existence of such a particular theory in the first place?"
] | [
false
] | null | [
"One reason is because it is possible to model most of the \"fundamental\" forces using the same theoretical framework: quantum field theory. Moreover, the fact that the electromagnetic interaction and the weak interaction have been successfully unified into a single quantum field theory -- that of the electrowea... | [
"I think it is partly because so many disparate phenomenon have been unified into single simple theories in the past. For example, phenomena that originally appeared to be unrelated to one another such as electricity, magnetism, and light were all eventually unified into a small set of equations (Maxwell's equation... | [
"One reason I've heard given as motivation for a search for a Theory of Everything is that Quantum Mechanics and General Relativity are the most accurate theories we've made, and they're mutually exclusive. That is to say, they can't both be correct. That they both can predict so many things so well makes us believ... |
[
"What would be the significance of discovering a magnetic monopole?"
] | [
false
] | I've been wondering this for a while. Edit: I mean this as in both practical significance and also mathematical, i.e. completing any current models. | [
"It's actually pretty easy to rewrite Maxwell's equations to allow for magnetic monopoles - you just assume that there is a magnetic charge particle, and the magnetic side of the equations becomes exactly symmetric to the electric side.",
"\nActually, it would make some things much more symmetric, and many attemp... | [
"Good answer. Let me just add that if magnetic monopoles exist, it gives us a ",
"nice, elegant explanation",
" for why charge is quantized."
] | [
"Maxwell's equations are less fundamental than quantum electrodyanamics."
] |
[
"Why is heat emitted as infrared?"
] | [
false
] | I understand all objects above 0 Kelvin emit thermal energy in the form of infrared but why is it that specific part of the spectrum and not radio waves or visible light for example? | [
"I understand all objects above 0 Kelvin emit thermal energy in the form of infrared",
"Then you misunderstand.",
"All objects above 0 K emit thermal radiation, which takes the form of electromagnetic radiation. The frequency profile and total intensity of the thermal radiation depends on the temperature of the... | [
"These objects emit the bulk (or all) of their thermal radiation in the part of the spectrum that we call infrared",
"Incorrect (\"all\"). The intensity of blackbody radiation at any given frequency monotonically ",
" with temperature. A very cold object radiates only in the microwave band. A hot object may ... | [
"There are some very hot neutrons stars and white dwarfs that radiate significantly in xray spectrum."
] |
[
"Besides size conatraints, why couldn't we attach a steam engine to a conventional engine and use the excess heat to give the engine more power/gas mileage?"
] | [
false
] | null | [
"We use heat from an internal combustion engine to drive a turbine which forces air back into the intake plenum. This is a turbocharger and it effectively makes great use of otherwise wasted energy.",
"As the engine goes through its 4 cycles (combustion exhaust compression and intake) it releases the exhaust fume... | [
"There is an engine that already does this. Look up Bruce Crower’s Six-Stroke engine. It adds an additional two strokes to a standard 4 stroke engine. It injects water into the hot cylinder and creates steam which adds a second power stroke. "
] | [
"I designed a small part of a power plant that operates in such a way. In general, this is called \"combined cycle.\" ",
"https://en.m.wikipedia.org/wiki/Combined_cycle",
" ",
"This is the plant I worked on. ",
"http://www.duke-energy.com/about-us/edwardsport-overview.asp",
" ",
"As you might imagin... |
[
"What am I doing to my eyes when I intentionally blur them?"
] | [
false
] | Not sure if it's something only I can do or not. But when I sort of "tense" my eyes, my vision blurs. Whats the point of this? | [
"Most people can only focus on whatever's in the middle of their field of vision, but apparently some, like you, can change focus at will. When you blur your vision, you're exerting conscious control over your eyes' focusing muscles to make your lens focus on a point that's not occupied by something that would be i... | [
"That seems really surprising to me that other people claim to not be able to do that. I can easily focus my eyes anywhere from ~6'' to infinity at will no matter what I'm looking at. It's an amusing way to entertain yourself by manipulating the star-shaped distortions of street lights at night. (I.e., trying to ma... | [
"You've got a lens in your eye that is essentially a clear sac of liquid protein. Muscles in your eye can shape that sac into a lens that is adjustable to whatever your brain wants to look at. It's like a dynamic magnifying glass in your eyeball, and some people can control it more than others. ",
"Probably other... |
[
"Theseus' body, is there any part of a human that is cellularly or even atomically stagnant?"
] | [
false
] | As an extension of the riddle of Theseus' ship I was wondering if all of the human body eventually grows a replacement. I know skin and other cells die and are replaced but what about other parts. I know some things won't heal sometimes like tendons, ligaments and cartilage; do they get replaced? I also thought neurons didn't re-grow. however even if we don't get new individual neurons are the cells themselves static? Or do they get internally replaced at a lower level such that although we can recognize it's existence as contiguous (much like ourselves as we get replaced) that it too suffers from a micro-Theseus dilemma? if nothing is the same how many years does it take to be essentially completely replaced? | [
"Sensitive cells in the ear (",
"hair cells",
") are created once, and for life. They are notoriously non-replaceable, and if they die because the ear is exposed to a loud noise, then, well, that's it. No hearing for this set of frequencies, ever.",
"The reason for that is, probably, that the ",
"cochlea",
... | [
"Some cells are replaced far more slowly than others. Sperm and blood are constantly being made and destroyed but osteocytes in your bones take far longer to be replaced (>25 years). Almost every cell in your body will be replaced every decade. ",
"Cartilage, ligaments and tendons can heal and be replaced at a ce... | [
"That's really fascinating. so yes dead cells would indeed not change in a human. I just wasn't sure we had any that never got replaced (hair/nails regrow constantly) ",
"so i guess every 7 years you may be a new person, except for your teeth lenses and ossicles."
] |
[
"Must all body proteins be synthesized from amino acids or can ingested protein be used directly?"
] | [
false
] | [deleted] | [
"I am unaware of any proteins being able to cross the brush boarder or any of the junctions present in our digestive tract. They simply are too large to effectively cross the membrane. As I'm sure you know the process of protein secretion from cells is highly regulated and requires a large pool of snares, binding p... | [
"You are absolutely correct! Creutzfeldt-Jakob Disease (CJD, aka the human form of Mad Cow Disease) and Kuru occur due to gut absorption of proteins. How this is possible, given the protease-laden environment of the stomach and small intestine, has been the topic of a lot of research. There are two prevailing th... | [
"These mimic enzymes that are functional in the intestinal lumen to break down lactose into it's constituent monosaccharides, glucose and galactose . These are often either are encapsulated to prevent degradation by digestive enzymes or are able to properly function at the low pH of the stomach. The enzymes are not... |
[
"How do micro-organisms see/sense other things?"
] | [
false
] | [deleted] | [
"Chemotaxis",
": specialized proteins are distributed on the membrane of the micro-organism, that act as sensors: they can assess the concentration of different molecules, thus allowing the organism to perceive gradients in its environment. It will consequently adapt its behavior: move towards the source of chemo... | [
"Vaguely related - ",
"quorum sensing",
". Basically, certain microbial behaviors, including motility, are regulated by the population size of a bacterial species in a particular environment. "
] | [
"Thats amazing! I never knew such a thing existed. Do you think that chemotaxis might be related to how a neuron cell's dendrites and axons find eachother? "
] |
[
"Which would kill you faster, a starvation diet or a diet of ~2000 calories a day of candy?"
] | [
false
] | My parents used to me that candy would kill be faster than starvation as a means to dissuade me from eating them. Is the claim true? I'd have to assume different candy would have different effects, but for arguments sake lets say it's just the 'pure sugar' types. | [
"Starvation. You'd have health problems from the candy but you'd be dead in a month or two eating nothing at all."
] | [
"Most likely a lot longer: beer is like floating bread, plus water. Water and bread is better than just water. You could survive for several months on just bud light."
] | [
"Much less time, because I would rather die agonizingly of dehydration than drink Bud Light."
] |
[
"Does a body of water exhibit a curvature in its surface due to gravity drawing every point on its surface to the earth's center of mass?"
] | [
false
] | Stated another way, do opposite ends of a surface of water, being both drawn to the center of the earth with equal force, angle outward? I already know this will be tough to explain, but I'll try. Imagine the surface of a body of water, whether in a glass or a bucket or an ocean, to have edges at points A and B. Gravity draws both A and B toward the same point in the center of the earth. Therefore the force of gravity vector to A must form a very very small angle with the force of gravity vector to B. Does this angle difference manifest in the surface of the water? Scale must matter, and it is probably too small to be realistically observable, but does this phenomenon occur? | [
"Yes otherwise, very simply, the oceans would not wrap around the planet."
] | [
"Yes, oceans have horizons."
] | [
"Large bodies of water do curve with the shape of the earth. It's not noticeable on the scale of normal day to day experience (in the same way the curvature of the earth is not noticeable). If you are careful about your measurements you can detect this. Someone won some money off a Flat-Earther back in the 1800's ... |
[
"If someone jumped off of a building, and were tackled at full speed right before they hit the ground, would either party survive?"
] | [
false
] | I was arguing with my friends recently about this; I will attampt to explain. Someone jumps off of a building and is travelling at a speed that if they hit the ground they would die no matter what. If someone came from the side and tackled the falling person at the last second (maybe 2-5 feet above the ground), would either of them survive? | [
"It would be hard to tackle them in any meaningful way without exerting an upward force. A person falling 100m will only take about 0.03 seconds to travel that last meter. If no upward force occurs, that tackle will be little more than a nudge, which will be of no benefit to them, and little harm to our would be ... | [
"There's two components of velocity, and therefore momentum, here; vertical (mostly contributed by the falling person) and horizontal (mostly contributed by the tackling person).",
"Considering the horizontal momentum first, the tackling person will give some degree of their horizontal momentum to the falling per... | [
"PoopMachin3 didn't ask what units you're talking about, but what quantity. If you're talking about velocity it doesn't make a difference whether you're talking about meters per second or miles per hour, but it does make a difference if you're talking about velocity, force, kinetic energy, etc. The laws are uphel... |
[
"In a rotating black hole, what is rotating?"
] | [
false
] | Just something that crossed my mind recently, since the horizon isn't made up of anything. What is the rotating. Or is it just a way to allow for the conservation of angular momentum without having to go inside the BH with our current understanding? | [
"The black hole has angular momentum, it may not make sense to speak of anything rotating (at least in a model where you have a 0d point or 1d ring singularity), just like you don't think of electrons as rotating because they have spin."
] | [
"When a macroscopic object rotates it has angular momentum. Elementary particles can have intrinsic angular momentum (spin) without a sense of \"classical rotation around its axis\" associated with it."
] | [
"Just to add to this, I believe the rotation is real and noticeable though relativistic frame dragging of the surrounding space-time."
] |
[
"Why do return trips feel shorter?"
] | [
false
] | null | [
"Well, this seems quite subjective. I for one find the return trip 'seems' much longer."
] | [
"I've noticed a similar phenomenon, in that when I'm watching a television program television, playing a game, reading a book, etc. for the first time, it seems to take a lot longer than subsequent times. I will often think \"Wow, it sure felt like it lasted a lot longer\" when I watch a television program again. I... | [
"+1 to that.",
"I guess it really depends on your state of mind during the trip."
] |
[
"Is there anything at the center of a gas giant? Does it have a metal core of some sort to keep the gas contained in a gravitational field?"
] | [
false
] | [deleted] | [
"Yes, hydrogen is supposed to be in a metallic state close to the core. That wikipedia article explains it pretty well.",
"Gas would contain itself in gravity the same way Earth's rocks do. All matter has gravity, it's just that it's a very weak force so for it to be perceptible you need a huge mass, like a plane... | [
"Yes, hydrogen is supposed to be in a metallic state close to the core. That wikipedia article explains it pretty well.",
"Gas would contain itself in gravity the same way Earth's rocks do. All matter has gravity, it's just that it's a very weak force so for it to be perceptible you need a huge mass, like a plane... | [
"With current measurements, it's impossible to know for certain. Theories about the formation of Jupiter suppose that a rocky core about 10 to 40 Earth masses provided the initial gravity to hold all the gas together. But hydrogen is a powerful solvent, and the properties of materials at such high temperatures and ... |
[
"Animals wake up and execute actions immediately, why do humans take significant time to do the same?"
] | [
false
] | null | [
"I find your question interesting, but I disagree with your hypothesis. Having been around various animals throughout my life both in domestic settings and in the wild, my observations have been that animals have a very similar reaction to the state between sleep and consciousness. Animals upon waking are known t... | [
"I think you are mistaking animals sleeping and simply resting.",
"It's like if you were just lying down on the couch waiting for the pizza guy vs. actually sleeping."
] | [
"Human's are animals. Your premise is false."
] |
[
"Would it be possible to refuel a dying star with a smaller, younger one?"
] | [
false
] | My train of thought was taking me to the prospect of Sol becoming a red giant, and I was thinking, provided a body could be moved and collided with a dying star, without disrupting the orbits of its planets, could one extend that star's longevity? | [
"Absolutely. This actually happens (though in a slightly different fashion) relatively often to stars in binary pairs where one star is more massive than its partner. A star's lifetime on the Main Sequence (its hydrogen-burning phase, like the sun right now) is correlated with it's mass - higher mass means shorte... | [
"This actually happens in globular clusters, see ",
"here",
". ",
"Here",
"'s a link to a scientific study where they actually observed two stars merging! Isn't that crazy?",
"You'd extend the life of the almost out of fuel star, but you'd significantly reduce the amount of time the younger star would l... | [
"Sounds neat! Would a red dwarf, for example, perhaps be able to keep a stable orbit for a while inside the expansion of a neighboring star?"
] |
[
"Could someone please provide a layman's explanation to the Susskind Solution to the Black Hole Information paradox and correct my layman's statement of the problem?"
] | [
false
] | Here's my statement of the problem: | [
"The idea you are talking about is the ",
"Holographic Principle",
". Essentially what it is saying is that the information about the incoming particle is encoded on the event horizon of the black hole. The event horizon is the boundary surrounding the black hole where your escape velocity exceeds the speed lig... | [
"Effectively you can represent the information from the 3-D world, in a 2-D object (the event horizon, a 2-D surface). Much like a hologram."
] | [
"Yeah, so in the analogy, the 3D components (velocity) of the bowling ball are imprinted on the 2D sheet of the trampoline (as elastic potentials in this example)."
] |
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