title list | over_18 list | post_content stringlengths 0 9.37k β | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"As you approach the speed of light, does the CMB in front of you get blueshifted?"
] | [
false
] | And similarly redshifted behind you? | [
"No, you can have a speed relative to the CMB and it can be sufficiently high that those harmless microwaves start turning in to dangerous x-rays and thus compromise the shielding of your craft."
] | [
"Yes."
] | [
"I'll try to expand slightly on the existing answer.",
"As ",
"/u/somedave",
" explained, \"approaching the speed of light\" is an ill-defined thing as your speed depends on the referential. The CMB as we observe it has a ",
"dipole anisotropy",
", meaning that it looks hotter in one direction than the op... |
[
"Why do seasonal temperatures appear to lag behind the solstices?"
] | [
false
] | The winter/summer solstices seem to be at the beginning of each season. Why do winter/summer temperatures lag behind the point at which the Earth is most tilted? Why don't the winter/summer seasons 'straddle' the solstice with equal parts before and behind? | [
"Because of climate. The biggest contributor is the high heat capacity of water; one has to insert a lot of heat, by volume, into water to change its temperature by a single degree (or extract a lot of heat to cool it by one degree) this means large bodies of water are like \"temperature regulators\" that are vast... | [
"First, I think it's really important to mention that some words used by scientists have made it into common vernacular. Even though words change meaning over time, words in science and math do ",
" change meaning hardly ever. While many people use the word \"theory\" to mean something that has no evidence or a g... | [
"As long as the heat loss exceeds the heat gain the temperature will fall. In early January the heat loss is greater than the heat gain the temperature will continue to fall. Only when we reach mid February does the heat gain exceed the heat loss, and we start to see temperatures rising.",
"\nThink of it as a b... |
[
"Can you drown someone with water vapor?"
] | [
false
] | Is it possible for water vapor to be so dense that a person drowns by breathing it in? | [
"The maximum humidity at ambient temperature is still only a small percentage, nowhere near close to enough to start displacing oxygen.",
"You could do it with water ",
" its boiling point, but drowning is the least of your concerns then."
] | [
"You can't physically displace air with water vapor (edit: ",
"at normal temperatures, anyway",
"). You could seal a room, pump out all the air, and pump in water vapor, but that wouldn't really be drowning, that would be just suffocation from lack of oxygen."
] | [
"Oxygen and Nitrogen in air are diatomic molecules. 32 g/mol and 28 g/mol, respectively. You would not want to breathe in a bunch of free oxygen atoms."
] |
[
"How are new alloys discovered?"
] | [
false
] | Is there a significant trial and error process to discovering new alloys? For a given application, how are the precise proportions of an alloy's constituents determined? Is it common to build upon pre-existing "recipes" to develop new alloys? What facilities and personnel are involved? Thanks in advance! | [
"this answers a lot thanks! it really does seem like researchers just try a new brew and throw a bunch of science at it to see what happens. thanks for your response :) im gonna look into the xray and dsc stuff too. wikipedia here i come"
] | [
"this answers a lot thanks! it really does seem like researchers just try a new brew and throw a bunch of science at it to see what happens. thanks for your response :) im gonna look into the xray and dsc stuff too. wikipedia here i come"
] | [
"ya know that doesnt sound half bad. my discipline is math and statistics. im trying to follow a data science path and i want to work with biological data. if there is a well developed statistics side then i think i could find a niche in the materials community. even better would be getting involved in biomimicry (... |
[
"Could our universe be the singularity of a black hole?"
] | [
false
] | null | [
"Hi fra5436 thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the followi... | [
"Hi fra4536. This would probably be better served at ",
"r/asksciencediscussion",
". Thanks for submitting and don't forget to flair!"
] | [
"Thank you"
] |
[
"How absorption into the lungs works?"
] | [
false
] | I have a basic understanding of chemistry and biology but an in-depth answer to this is something I can't find anywhere. In regard to smoking how does chemical absorption into the bloodstream via the lungs work? Whether it is nicotine, THC and CBD or even Methamphetamine /Other hard drugs how quickly is the active chemical absorbed? If someone holds their breath for say 10 seconds and then breathes out, has all of the primary active chemical absorbed by this point and if so what makes up the smoke/particles that are exhaled? Or would the breath need to be held until nothing is visible on the exhale for everything to have been absorbed? Any expansion on this would be greatly appreciated. Many Thanks. | [
"Chemical absorption via the lungs works like chemical absorption across nearly every epithelial tissue in the body:",
"β",
"All the substances you listed are small, polar molecules and so pass readily through the lung epithelium. Gas exchange in the lungs occurs at small structures called alveoli which are thi... | [
"Excellent reply. I had lost hope and presumed that my question would be lost to time.",
"You have done a great job articulating and expanding what I though to be the case. ",
"One further question. Further holding of your breath will increase absorption but is there likely to be a point (this is what I suspect... | [
"It would depend on the concentration of the desired substance in the drag. As long as there is a concentration differential, substances will flow down their concentration gradient.",
"β",
"But since no process is 100% efficient, especially in biology, holding a hit longer will increase absorption, with decreas... |
[
"What has humanity done to protect against large coronal mass ejections (CMEs) and solar flares?"
] | [
false
] | I've recently read about the dangers they pose to our electricronics and I'm curious as to how screwed we'd be | [
"I have a rather contrarian position on this. We protect against large geomagnetic storm events the same way we protect against any other power surge: circuit breakers.",
"The perception among the nerd public is that a major geomagnetic storm would be a civilization-ending event, with every electronic device des... | [
"Unfortunately, not much. While we would have some advance notice (a couple days), there's little that we could do to prevent its effects.",
"How wide-spread would these effects be? ",
"A flare in 1989 led to a geomagnetic storm that ",
"wiped out the power grid in Quebec",
", leaving folks without power fo... | [
"So, \"phrasing\". A wiped out power grid does not restore power in a few hours. Wiped out means ded, gone. Ain't there no more. Zilch. Zippo. Also, utilities have begun installing grounding equipment to isolate and ground induced currents in long haul power distribution lines. A long way from done, but it is a st... |
[
"When I stub my toe, why is the initial pain less intense than the pain I feel 2 seconds later?"
] | [
false
] | null | [
"This is accurate.",
"One of the interesting things about nociception (pain perception) is that it is somewhat unexpectedly slow. That is, one might expect that the fastest, most important signal from touch receptors to your brain is \"ow, that really hurts,\" but, as dustcarti mentions, other signals are faster... | [
"This is accurate.",
"One of the interesting things about nociception (pain perception) is that it is somewhat unexpectedly slow. That is, one might expect that the fastest, most important signal from touch receptors to your brain is \"ow, that really hurts,\" but, as dustcarti mentions, other signals are faster... | [
"It likely has something to do with where the fibers terminate. The A delta fibers eventually terminate at the somatosensory cortex, which allows fine discrimination of the pain. It's a very analytical scenario for the brain. \"I have a very specific type of pain coming from just off center of the tip of my finger\... |
[
"Does every latitude experience the same amount of annual sunlight?"
] | [
false
] | So would the south and north pole experience 6 months of total sunlight per year as well as the equator? | [
"In terms of ",
" the Sun spends above the horizon, yes, over a year it averages out to be the same everywhere on the planet. In terms of ",
", though, it does not.",
"While the Sun does remains constantly above the horizon at the poles for 6 months out of the year, the highest it ever gets is 23.5 degrees (w... | [
"Correct me if I'm wrong, but wouldn't the South Pole get (slightly) more daylight per year than the North Pole?",
"My reasoning comes from the fact that Aphelion occurs in roughly the middle of Southern Hemisphere summer, and Perihelion occurs in the middle of Northern Hemisphere summer.",
"What I would like t... | [
"My reasoning comes from the fact that Aphelion occurs in roughly the middle of Southern Hemisphere summer, and Perihelion occurs in the middle of Northern Hemisphere summer.",
"You have that backwards - currently perihelion occurs in early January, aphelion occurs in early July.",
"This ",
" very slightly in... |
[
"Why do physics break down above the Planck Temperature?"
] | [
false
] | [deleted] | [
"It's not so much that physics breaks down or that it's the hottest possible temperature, but rather that we can't really understand things that hot without knowledge of quantum gravity (because particles could be colliding with such great energy that they form black holes), which we don't understand well enough."
... | [
"Temperature is related to the speed of the Brownian motion of particles, right?",
"More precisely, it's related to their average kinetic energy. The distinction is that there is no limit on how much kinetic energy a particle can have (if it has mass). ",
"Wouldn't that imply a maximum possible temperature when... | [
"Temperature is related to the speed of the Brownian motion of particles, right? Wouldn't that imply a maximum possible temperature when all the particles are going at c?",
"I am aware that that isn't actually how temperature is defined, but I've never understood the more technical definition."
] |
[
"Could dolphins or elephants have taken the same role of humanity or were our limbs a prerequisite to the way we evolved?"
] | [
false
] | null | [
"We can't answer such hypothetical and speculative questions definitively."
] | [
"Right, I wasnβt looking for a definitive answer, just a thought experiment of sorts, was hoping to see some discussion from particularly knowledgeable people on why or why not it wouldβve been likely for another species to take our place. Itβd be cool to learn about the effect our ability to physically manipulate ... | [
"Not the right sub for such speculation. Maybe try ",
"/r/askreddit",
" or ",
"/r/asksciencediscussion"
] |
[
"Are Chiropractors Quacks?"
] | [
false
] | This is not meant in a disparaging tone to anyone that may be one. I am just curious as to the medical benefits to getting your spine "moved" around. Do they go through the same rigorous schooling as MD's or Dentists? This question is in no way pertinent to my life, I will not use it to make a medical judgment. Just curious as to whether these guys are legitimate. | [
"There are multiple schools of chiropractic 'medicine.'",
"Many chiropractors use manipulation to treat musculoskeletal pain. There is ",
"weak evidence",
" that chiropractic may help relieve lower back pain, although it may not be any better than standard medical treatment.",
"Many chiropractors also use ... | [
"Here's the thing, though: even chiropractors that are fairly mainstream and focus solely on musculoskeletal pain fail to follow the scientific method. They base much of their practice on anecdotal and experiential methods along with whatever seems like it might work. As a result, they fail to disclose a lot of ... | [
"Below are some excerpts from a paper I wrote regarding chiropracty. I fully support the claims that chiropractic medicine is quackery. Sorry for the multiple post but I couldn't fit it all. Enjoy. ",
"Chiropractic care has been around since the late 1800βs, invented by D.D. Palmer, he defined it as βthe scien... |
[
"How are people's gender identified medically?"
] | [
false
] | How do you make the determination? There are people of mixed gender, and I'm curious as to how each person is supposed to be identified medically to determine dosages. If different drugs are metabolized differently for a male than for a female. What is this based on? Is this based on just a different metabolic rate, or water weight. | [
"First of all, people's ",
", not gender, is what is determined genetically / physiologically / morphologically / anatomically at birth. ",
"People's ",
" is a separate thing: it is the sex of behaviors and other cultural constructs they identify with. ",
"Historically, people's sex and gender used to the s... | [
"In general, drugs aren't dosed differently for different sex, race, or genetic variability, although these factors influence how the drug acts of the person, and how the person metabolises or clears the drug. In practice, the variable dose drugs are dosed by weight or the dose is titrated to a measured plasma drug... | [
"For trans/mixed gender patients I usually chart something like \"genotypic male, phenotypic female, prefers to be called...\" Determining genotype is important because the patient may receive testing that is not useful for their sex (and be charged for it!), such as a pregnancy test. Their identifying gender is i... |
[
"Have any QUALITY studies been done on the long term effects of LSD, mescaline and/or psilocybin use?"
] | [
false
] | null | [
"Dr. Roland Griffiths has been doing excellent work at John's Hopkins University School of Medicine. His studies are multi-year; he follows the lives and personality changes of people that have taken hallucinogenic drugs. His work is very rigorous and not all that controversial when compared to someone like Dr. T... | [
"Ahhhh yea, this is the stuff I'm talking about. Good find."
] | [
"Do you consider Timothy Leary's work to be quality? Much of his work was in the use of psychedelic and hallucinogenic drugs for therapeutic purposes. As to whether or not his methods and procedures hold up to current scrutiny of the more intense variety, that depends on perspective, but in this untapped field, t... |
[
"How does one freight engine pull 100+ train cars that weight more than a ton each?"
] | [
false
] | It occurred to me while watching a train go by obviously. I would guess it is similar to a human pushing a car in neutral; even though the car weighs 2000-3000lbs it takes relatively little force to break the static friction. Is this a similar situation? What kind of torque are in the engines? EDIT: Thanks for all the answers so I have an additional question then; what about when a locomotive has to go up hills/mountains? Momentum can only take you so far. Then it really is the engine pulling the weight of the carts. Do they have to pay close attention to the weight of the carts if they know it has to take these tracks? I.e. they have a maximum load certain locomotives can carry on these tracks? | [
"A modern diesel locomotive can make anywhere from 4,000 to 6,000 horsepower and they often work 2-3 to a train, depending on how long/heavy it is."
] | [
"An additional factor is the hookups between cars. There's a small amount of slack in each connection, so from a dead stop an engine is only accelerating the car behind it at first, then once the connection is taut it has the inertia of the engine and the first car to help pull the second car, and so on down the li... | [
"An additional factor is the hookups between cars. There's a small amount of slack in each connection, so from a dead stop an engine is only accelerating the car behind it at first, then once the connection is taut it has the inertia of the engine and the first car to help pull the second car, and so on down the li... |
[
"Why is Kilogram the S.I. unit for mass, and not the gram?"
] | [
false
] | It really frustrates me. Why wasn't the weight we call a kilogram defined as a gram? It's the only one with a multiple prefix, why do this? | [
"Because the French are "
] | [
"That's ",
" kilogram to you, monsieur."
] | [
"If this is the thing about science that frustrates you, just wait a few more years."
] |
[
"Why do we use the Joule-Thomson Effect for refrigeration?"
] | [
false
] | Putting compressed gas through a nozzle to let it expand and cool (Joule-Thomson Effect, as used in every fridge and air conditioner) seems inefficient for cooling. Why don't we instead take the same volume, pressure and temperature compressed gas and make it do work by putting it through a turbine? Even if the energy from doing the work were entirely wasted, the resulting gas would be significantly colder, and therefore better for refrigeration. In reality, we could also use the energy from the turbine, potentially gearing it to the compressor to reduce electricity usage. EDIT: It seems what I'm describing is a . Wikipedia reports them as more efficient than regular throttling nozzles, so I guess my question becomes "Why doesn't everyone do this if they're more efficient?". | [
"Turbines can only really do work on dry vapor without being completely destroyed by cavitation. The real energy storage/ release is usually in phase change, so that makes turbines impractical for that kind of task. "
] | [
"\"Why doesn't everyone do this if they're more efficient?\"",
"I work in Automotive Climate Control. Cost and reliability are the biggest drivers in the auto industry and this sounds like something that wouldn't make a large system wide difference, but would add headaches in terms of things like reliability and ... | [
"Not only that, the are very few parts in comparison. Less parts=fewer ways for it to break and lower cost. The low pressure side of a refrigerator's sealed system is created by using a capillary tube, so only a little can get through at a time, and having the compressor on the other end of the low pressure side, s... |
[
"Why is there a lack of blue fruit?"
] | [
false
] | Why are there so few blue fruits? The only blue fruit I can think of is the blueberry. Plums and grapes are purple, so I guess they sort of count. Most of the other fruit in the world is red, green, yellow, or orange. | [
"The pigments that plants produce (like chlorophyl in leaves or lycopene in tomatoes) are all organic molecules that are fairly large and called \"conjugated systems\" because they can \"spread\" their electrons out across the carbons in a special way (see ",
"wikipedia",
" for a less vague way of discussing th... | [
"like copper in chlorophyl.",
"Surely you mean Magnesium."
] | [
"yep"
] |
[
"If the recent news about Mars is true,"
] | [
false
] | [deleted] | [
"Guys, please refrain from anecdotal evidence or layman speculation."
] | [
"Mars' atmosphere is around 0.6% the density of the Earth's, and is almost entirely CO2. If you could somehow turn all of that into O2, you'd still have around 1/50 the amount of oxygen that we have on Earth. "
] | [
"Here's the problem with life being on the surface of Mars. The atmosphere is WAY too thin meaning that high levels of cosmic radiation bombard the surface every second. The radiation would damage the DNA to the point where life could not exist. There are certain species of bacteria that are great at surviving h... |
[
"Why are cases of dementia more common in North America and Europe compared to the rest of the world?"
] | [
false
] | null | [
"People live longer in developed countries compared to developing countries. They are also more likely to see a doctor on a regular basis which would allow them to diagnose such a thing. So the actual incidence may not be too different, just documented more.",
"A possible cause could be related to diet and life s... | [
"Reliable information is probably harder to get from poorer countries especially for mental illnesses which carry a bit more stigma than most. Reporting, diagnosis and treatment being more available in wealthier countries. ",
"It is probably hard to make the conclusion you state in the title."
] | [
"Next to the living longer and better documented answers that have already been given, it might be that genetics could also play a role. For example, the tau locus (tau being one of the two dysfunctional proteins in Alzheimer) is robustly reported to be associated with Caucasian populations, but could not be replic... |
[
"Can /R/AskScience give me a scientific explanation to why Miller Light's Vortex Bottle does not work?"
] | [
false
] | I was drinking a Miller Light while rewriting my thesis. I'm very serious. | [
"Air pressure differential. Being in an enclosed bottle there isn't any difference, it just depends on how fast you an gulp it down. Also, the bottle won't allow the beer to \"shoot\" into your belly due like they advertise. However, you can still \"shotgun\" from a ",
" with nothing more than a ",
"straw",
"... | [
"Can you explain what the \"Vortex Bottle\" is advertised to do? (I shut my brain off and refuse to listen to any of their commercials)"
] | [
"http://vimeo.com/23290667"
] |
[
"I've noticed that there are two possible configurations for the directions of the oars in the coxless four rowing. Are there any advantages/disadvantages of one configuration over the other?"
] | [
false
] | I figured this was more of a physics-based question, so I posted it here. I was watching the men's coxless four final when I noticed that there were two configurations for which way the oars could point. Australia had the regular alternating configuration of left- and right-handed rowers ( ), but all of the other teams were oriented so that the two middle rowers were of the same handedness ( ). What is the reasoning behind these choices? Is there any truth behind them? I'd imagine that the alternating method is the more classic version and, at some point, the other method started being adopted. I'm curious to know if there are any benefits of one method over the other and if they would be most useful in particular circumstances. | [
"It's called bucket rigged. ",
"It isn't about physics as much as you would think. ",
"In a four each person in the boat needs a slightly different set of skills, the bow has to be agile and the stroke has to have good rhythm. Bucket rigging the boat allows you to have the people you want in the spots you want ... | [
"The physics of it aren't too complicated. I was trying to explain this to someone else so I decided to make some diagrams with explanations: ",
"http://i.imgur.com/nA4k4.jpg"
] | [
"Awesome! Thanks for the diagram and explanation. So the main difference between the two methods is the amount of rotation that is created by the strokes produced by each individual rower, and the positions of the rowers are chosen so as to minimise this rotation? I hope I got this right."
] |
[
"Inspired by another question: Can damage to mucus membranes lead to greater susceptibility for colds?"
] | [
false
] | I've noticed that after a night of shouting myself hoarse at a football game, or waking up on a dry winter morning with a dry throat, that I'll develop a cold later that day. Is there any connection between damage to the mucus membranes and increased susceptibility to colds and other viruses? Or is this just confirmation bias? | [
"Mucous membranes and skin are the first line of defense against most microbes. So damage to those tissues will increase susceptibility to infection. Burn victims have to be kept in as sterile an environment as possible because of the many opportunistic microbes in the environment. If your membranes are intact thes... | [
"Yes. Just ask any smoker."
] | [
"Without a doubt. Many infections of the oropharynx (the area in the back of your mouth) can lead to increased susceptibility to additional, and often times worse, infections. The primary role of mucus membranes (aka mucosa) is as a barrier to infection."
] |
[
"Why don't alkali metals such as lithium and potassium react violently with water found within the human body?"
] | [
false
] | [deleted] | [
"The reason alkali metals react so violently with water is that they have only one electron in the valence shell, and they desperately want to get rid of that electron so that the outmost electron shell is full. They do this by giving away that electron to one of the hydrogens in water.",
"In your body these elem... | [
"Essentially, they already have reacted. If an animal were to take a piece of sodium or potassium or lithium metal internally, it would go poorly for them. "
] | [
"Yes, alkali metals in their ",
" react violently with water, producing hydrogen gas and the metal hydroxide (as ions dissociated when in water):",
"2 M + 2 H2O --> 2 M",
" + 2 OH",
" + H2 , where M=Li, Na, K, etc",
"The alkali metals in your body are already M",
" , so they do not react with water in t... |
[
"What is the difference between blood pressure and peripheral vascular resistance?"
] | [
false
] | [deleted] | [
"Blood pressure (mean) = cardiac output (amount of blood pumped over time) x peripheral vascular resistance.",
"Cardiac output = stroke volume of each heart beat * heart rate.",
"So BP will increase with PVR but PVR isn't the only factor. "
] | [
"Trying to explain this conceptually. Resistance is the opposite of conductivity. Physically resistance is the friction caused by the walls of the blood vessels, especially the peripheral vascular system. The longer the vessel, the higher the resistance; the smaller the radius of a vessel, the higher the resistance... | [
"I will assume then, that you are currently at a pretty basic level and would like a pretty basic answer?",
"Blood is basically a liquid in a series of tubes. Pressure is the measure of force over an area. A liquid will always exert some force onto the tubes that contain it. Blood pressure is just the force that ... |
[
"What does unplugging your electronics when not in use do for the environment/electricity bill?"
] | [
false
] | [deleted] | [
"Nowadays not a lot.",
"Modern electronic equipment has a negligible standby power consumption but it's not zero so there will be a micro saving. But boiling too much water in an electric kettle or letting warmed air leak from a leaky building will cause far higher power wastage than leaving your TV or PVR plugge... | [
"While you're right about pretty much all of this, there are a few electronic devices which consume just as much power on as they do in standby - PVRs (DVRs) being the worst culprit of them."
] | [
"If you're interested in how much electricity your devices use when not in use, I'd recommend a Kill-A-Watt device. It'll give you realtime information on watt consumption. The term for this is standby power, or I've always heard it called ghost load: ",
"https://en.m.wikipedia.org/wiki/Standby_power",
"In shor... |
[
"What's the atomic correlate of light passing through tranparant material more easily than through non-transparants?"
] | [
false
] | In other words: what is it that makes materials transparent? | [
"The electrons of the material don't scatter or absorb the wavelengths of light the material is transparent to. "
] | [
"http://www.youtube.com/watch?v=Omr0JNyDBI0",
"sixty symbols explanation. "
] | [
"The strength of the interaction between light of a certain wavelength and the electrons, which is a function of the energy and mobility of the electrons, which is determined by what material they are a part of. "
] |
[
"Diseases like influenza, and probably Covid-19, need a minimum amount of viruses to cause infection and disease. Why? Shouldn't a single virus be enough?"
] | [
false
] | So according to a multitude of sources, influenza viruses are floating almost everywhere where people are, suspended in tiny droplets in the air where they can remain airborne for days and are being inhaled by all of us. But the number of viruses we ingest this way is too low to cause infection and disease. The same is presumably true for the new coronavirus. But why is this? As I understand it, unvaccinated people get infected with the flu, and everyone with Covid-19, because our immune system does not yet know how to even fight back against these pathogens. The virus can basically operate in the organism unopposed and hijack our cells, until the immune system learns and starts making antibodies, at which point the infection is beaten back and we become immune to this particular strain, if we didn't die before that happens. So shouldn't a single virus be enough to start multiplying inside of us and eventually cause disease? And if our immune system can defeat a few copies of a virus despite not having a specific antibody for it, why can it not defeat all of them? | [
"It's a war in your body, your body defends itself against things coming from outside, just one single guy? Easily surrounded and eaten. 10? No problem! 100, 1000 and more is getting tricky, can you surround them and eat them before they hide in cells and start to force them to reproduce you? maybe maybe not."
] | [
"Our body has a number of protective mechanisms that act whether a virus is novel or not, that in concert would make it difficult(though I suppose not entirely impossible) for a respiratory infection to be caused by a single virus. ",
"Our respiratory epithelium cells are covered with a layer of protective mucou... | [
"So, would people with extra mucous production, say, due to asthma, have some extra protection against a virus?"
] |
[
"Why does both fission and fusion release energy? If splitting an atom releases energy, wouldnt fusing atoms require energy?"
] | [
false
] | null | [
"I'd recommend checking out the ",
"graph of nuclear binding energies",
". As you can see, there's a peak in that graph, approximately near iron (",
"Fe). If you want to produce energy, you need to increase the binding energy in a nucleus. This is not very intuitive, but the reason for this is that the bindin... | [
"To add on:",
"You read that graph starting with your starting elements and moving towards your products. In fusion, you're moving right; in fission, you're moving left. Hopefully that's not counterintuitive.",
"The binding energy comes from mass. This means that 1) the sum of the masses of the protons and neut... | [
"And not even really quickly in astronomical terms. Like really quickly as in like stopwatch terms. Like hours."
] |
[
"Is consciousness an all-or-nothing deal? Can it be \"improved\"?"
] | [
false
] | I know there is a fine line between science and philosophy, but I think this is more of a science question. Did humans just all of a sudden become sentient one day? Or did we "fade" into consciousness? Is consciousness binary? Do you either have it or you don't or are there different levels of it? Because if it is binary, then there must've been a first sentient being right? But then he/she reproduced with a non-sentient one? And if it's not binary, can humans over time "improve" our consciousness scientifically through evolution? | [
"Considering that we don't really understand anything about the phenomenon of \"consciousness\" or \"sentience,\" science can't really say anything about your questions. We must first figure out what we're even dealing with before we can address your questions."
] | [
"There was an experiment where a small LED was flashed twice in quick succession at individuals from two groups; Buddhists who engaged in meditation, and a control composed of any individual who did not meditate.",
"The buddhists who meditated reported seeing two flashes and their brain activity levels (on a micr... | [
"Science, by definition, deals with quantifiable, observable, falsifiable things.",
"\"Consciousness\", as you used it, is none of those things. What's the definition of sentient? Is a monkey \"more sentient\" than a dog?"
] |
[
"In space, how do astronauts measure small amounts of mass?"
] | [
false
] | [deleted] | [
"If you had a motor with an arm attached of known mass with a force sensor built into it and something to put the object being measured inside at the end, then you could spin the motor to a known speed and measure the force to calculate the objects mass. I dunno how they actually do it though."
] | [
"I don't know how they DO measure it, but you could set up two springs with the mass in the middle and measure the period of the oscillations."
] | [
"Not sure about small masses, but for weighing the astronauts they use a spring with a known spring constant. Attach the mass to the end of the spring and pull it off center, and when released it will oscillate with a period that depends on the mass. ",
"For a spring constant k and oscillating frequency f, the ma... |
[
"Do anti-aging creams really prevent wrinkles in the long-run?"
] | [
false
] | I've avoided these creams based on my assumption that they may prevent wrinkles in the short-term, but the chemicals would eventually take a toll on my skin. I have been using natural oils instead. : What I am really interested in, and should have asked in the first place - Is it possible that anti-aging creams could actually be harmful, even contribute to aging in the long-run (due to chemicals, etc)? | [
"No. Wrinkles are cause by repeated replication of cells. As cells replicated more, their copies aren't as good as the original. After billions of replications, the skin cells are unable to as strong and smooth as the once were. The \"weaker\" skin cells are pressure by muscle contractions to form wrinkles in place... | [
"Some of them just cover wrinkles with goop, and some of them are complete scams and don't do anything. Some might help with hydration, but I doubt that they would do harm. And as virnovus said, protecting from the sun's radiation would slow the cells aging. But that would only work for creams that you apply, then ... | [
"Well we know there are ways delay aging (or to cause premature aging) of the skin, eg. eating healthy, not smoking, etc. So although aging is inevitable, I'm wondering if these creams actually slow down the process, or could they even be harmful?"
] |
[
"How does a car determine its speed?"
] | [
false
] | I was thinking it can't be a simple revolution counter of the wheel, because if you change the size of the wheel the distance covered will be different. So how does the car "calculate" its speed accurately? | [
"It is done by counting revolutions, of the wheel, axel, transmisson, ect. And yes, changing the tire size does change the calculations, which is why you are supposed to have it recalibrated if you do change tire sizes. "
] | [
"I did the math years ago and for a 2005 Subaru Forrester with properly inflated tires the maximum deviation is 3 mph due to temperature and pressure variations. This error is swamped by parallax error from reading the dial if you are tall. So the errors in the system will not be enough to get you out of a speeding... | [
"Additionally, in Australia the applicable standard states no car speedometer is allowed to show a speed lower than the actual speed.",
"Because of this, you will find cars commonly error towards the speedo showing a higher speed than actual. My car came out with a sports pack and relatively large wheels (18\"). ... |
[
"Assuming the reasons are scientific and not political, why will examining Arafat's body take three months?"
] | [
false
] | null | [
"My understanding was they wanted to do isotope tests for polonium-210 at two points in time, to determine... something. That's what the individual said in the interview I saw, but I'd like verification.",
"I'm not sure what information they could get from that, anyone with experience in radioactivity care to ch... | [
"I suspected that they were trying to do something with the polonium-210 and was hoping someone could chime in. Surely they can determine whether there's any there in less time, but perhaps the two measurements could be used to pinpoint when he was poisoned, or at least when the polonium was created? ",
"Thanks f... | [
"This says that it should take 40-45 days to finish an autopsy...\n",
"http://www.healthcare.uiowa.edu/path_handbook/Appendix/AnatomicPath/autopsy.html",
"\nDefinitely shouldn't take 3 months... political?"
] |
[
"What limits the length of my body hair?"
] | [
false
] | [deleted] | [
"All hair follicles cycle between active growth (anagen) , paused (catagen) and shedding (telogen) phases. ",
"Hairs grow to their max length defined by the period of the growing phase (at approximately 1/8th of an inch per week) . This period is different for hairs on different parts of your body which is why yo... | [
"I'd guess some of this data exists but it's not really my field. I do know that the reasons why Clipper grade guards (1 through 8) are the size they are is because each grade is an additional 1/8th of an inch. So each grade represents about one week's growth. ",
"Anecdotally, from my own head shaving and manscap... | [
"Shouldn't the speed of hair growth also be a factor? Or is the growth speed the same (or close enough) for all different areas of the body?"
] |
[
"Are the aerodynamics correct in this article?"
] | [
false
] | I just saw this article: It says the lead goose in a migrating V formation does the hard work while the followers benefit. I always thought that the lead goose was the one benefitting because he is getting his wing tip vortices picked up by the geese on either side and it is the trailing goose that has the hardest work? Can someone clarify? | [
"Your thinking is correct in that something trailing a body can improve its characteristics by affecting the wake or tip vortices. However you have to be very very close, so trailing birds aren't going to noticeably affect the lead bird.",
"The article correctly mentions the \"wash-up\" of the lead bird. Tip vort... | [
"That's actually almost certainly an effect as well, though I'd have to run calculations to get an idea of the relative magnitude of the two effects (whether the aft birds are working harder or easier) - they're certainly coupled.",
"Because of that \"high aspect ratio\" effect the flock is more efficient than th... | [
"Ok. Thanks I get it. I used to fly gliders out of an airport in upstate New York. The geese would fly over sometimes and this topic came up once. The person who brought it up equated the flying formation to a high aspect ratio glider; that the geese flew more efficiently but it was the goose at the end that shed t... |
[
"How effective are antidepressants and anti-anxiety medications? Is there physical evidence of their efficacy?"
] | [
false
] | I was recently told that many antidepressants and anti-anxiety meds don't actually work. I never heard this stance and I was incredulous, so I did some quick research and discovered articles that echo this view. (I've included some sources below.) Apparently SSRI's do not work better than a placebo unless the patient is extremely depressed. Do SSRI's have verifiable evidence for the alleviation of depression or anxiety? What about other drugs, like MAOI's or benzodiazepines? What are their physical effects on brain chemistry, and why would that help? Thanks in advance, . I've always had great respect for this subreddit. Sources: The following are a response to Professor Irving Kirsch's findings in 2008: | [
"I don't think antidepressants are really that different from any other medication. Sure some patients don't respond, but that's the case with many other drugs out there. The first link you cited doesn't say anything beyond that. ",
"The Kirsch paper (from the second and third links) you cited does argue that ... | [
"I've seen some of the evidence you write about. ",
"Even with this doubt on SSRIs, I think ",
" anti-depressants and anti-anxiety drugs may still have value.",
"I also understand that some SSRI's work better than others, that th4e best SSRI can be different for each individual, and it is difficult to predic... | [
"How do MAOI's differ from SNRI's?"
] |
[
"Why can't the James Webb Space Telescope see the full visible spectrum? Why are it's mirrors gold-coated?"
] | [
false
] | JSWT is stated to be able to detect wavelengths between 0.6 Β΅m and 28.5 Β΅m. The shorter end is due to the gold coating of the mirrors. Why not use different coating for at least the full visible spectrum (which starts around 0.4 Β΅m), if only for the obvious popular appeal of "true-color" images? | [
"Gold is more reflective in the infrared range than is aluminum or silver, which are used for mirrors for traditional visible telescopes.",
"For the things the JWST is looking to study, such as the most distant galaxies, visible light is considered less desirable for several reasons.",
"Among these is the fact ... | [
"Yeah, the idea is that with adaptive optics, it's not quite as necessary to put a telescope in space as it used to be. So the current projects are to build big 30-metre class optical telescopes on the ground, but go to space for wavelengths that you can't do so well in an atmosphere."
] | [
"Why not use different coating for at least the full visible spectrum (which starts around 0.4 Β΅m), if only for the obvious popular appeal of \"true-color\" images?",
"It wouldn't work as well for the infrared range."
] |
[
"Fine, nothing can get out of a black hole when free-falling into it. But can something accelerate out?"
] | [
false
] | For example if a rocket falls into the event horizon. Could it use its engine to accelerate out? As I understand it, if the rocket's acceleration counteracts the black hole's gravity, the rocket could move towards the outside of the event horizon at a constant, lower-than-light speed. In general, one could say that the only thing "trapped" in the black whole is the center of mass of a system. This consideration is used in some science-fiction novels, but is it true, or is there a flaw in the reasoning above? Would the action-reaction principle that propels the rocket's engine be limited in any way when inside the event horizon? Would the acceleration have a theoretical limit? I know that a lot of weird stuff happens to space-time near a black hole, so I would like to hear your ideas. I was asking this because the typical, simple explanation given for the event horizon is that, inside it, the escape velocity of a particle would exceed light's. This explanation does not account for forces acting on a particle that could "expel" a particle outwards even if its starting speed was below escape velocity; thus my doubt about the rocket. No, the rocket cannot get out. It has been pointed out by many redditors that, inside the event horizon, there is no such thing as a direction in space that points away from the black hole; any kind of movement will bring you closer to the singularity . It is therefore irrelevant whether the object is a free-falling particle or a magical rocket with infinity power. As I understand it now, it could be compared to being in the center of a hollow sphere that is quickly collapsing towards its center: no matter which way you go or what you do, you will be closer to the sphere's surface. It is your very position and the geometry of the sphere that defines this fact; you do not need to imagine forces or weird phenomena "restricting your options". | [
"Nope. Inside the event horizon, moving \"forward in time\" is equivalent to moving \"further down inside the black hole\"."
] | [
"Great explanation by RRC:",
"But it isn't. It's the absolute, literal truth. Inside the event horizon of a black hole, there is no way out. There are no directions of space that point away from the singularity. Due to the Lovecraftian curvature of spacetime within the event horizon, all the trajectories that wou... | [
"So, basically, the spacetime inside the event horizon is twisted in such a way that there is literally no \"outward\" direction.",
"Mind = blown.",
"This is exactly the kind of answer I was expecting. Why don't physics books have this sort of explanations? All this insight is very difficult to extract from jus... |
[
"Have scientists tried to make a coronavirus vaccine before COVID19? If so, was it successful? If not what went wrong?"
] | [
false
] | null | [
"A vaccine is available that protects dogs against Canine Coronavirus (CCoV).",
"As for human coronaviruses: There are 4 coronaviruses that typically cause a cold in humans. And combined these 4 only make up a small portion (10-20%) of all cases of the common cold. Consequently, there has been little interest in ... | [
"They're protecting against a different type of coronavirus, one that doesn't infect humans."
] | [
"They're protecting against a different type of coronavirus, one that doesn't infect humans."
] |
[
"Is there a reason that baldness in babies follows the same general pattern as Male Pattern Baldness?"
] | [
false
] | null | [
"I think you may have a flawed premise here. Babies generally don't follow male pattern baldness. If they have very thin hair, it is generally very uniform. ",
"Maybe someone else can give you a better answer, but I haven't been able to find a single example of a male pattern baldness newborn for about an hour no... | [
"Well I'm not going to pretend there are statistics on the issue, but it's just something I've noticed very frequently. ",
"A google of \"bald babies\" pulls up a large number of results which have the characteristic thinning on the temples that occurs in MPB. ",
"http://www.rookiemoms.com/wp-content/uploads/... | [
"No one is saying babies are lossing hair. The question is about if there is a pattern between how hair forms and grows in when compared to how it thins and \"grows out\"."
] |
[
"Does a gravitational field affect the path of gravity itself?"
] | [
false
] | Gravity distorts spacetime and this affects the path of light (photon). Gravity itself travels at the speed of light. Will it also be affected by the gravitational field? Could you get gravitational lensing of the strength of gravity from an object behind another? If light can't escape a black hole, why can the gravitational effect travel past the event horizon? Information can't escape, neither should the gravity, which provides info about the mass of the BH. I've never come across a discussion about the differences between light and gravity that explains away my confusion. | [
"While on the surface I think you're right, I wonder if its completely true. Let me pose a theoretical question:",
"Lets say you have VERY precise measurement equipment. There are three stars, one that we're on, and two that are far away in a binary system. This binary system creates gravitational waves/distortio... | [
"I suppose the simplest way to explain this would be that gravity hasn't self interaction. For example gluons, the force carrier of the strong force ( to quarks what a photon is to an electron) has color charge. A gluon can act on a gluon. It is this self interaction which causes the strong force to be so short ran... | [
"Gravity distorts space-time",
"This is a common misconception. It's not that gravity causes distortions in space-time, gravity ",
" space-time distortion. ",
"To elaborate, the presence of mass distorts space-time, and what we perceive as gravity is an emergent property of objects (such as light waves or pla... |
[
"Would music sound different with a different air density?"
] | [
false
] | I know sound travels in a wave, but does that mean that it would interact with something making a vibration or the way we hear it differently based on the air density? Say for instance I had a perfectly in tune guitar and hit the low E string at sea level and struck the same string on the top of Kilimanjaro? What about Mars? | [
"A big factor that is not mentioned is temperature, at room temp the speed of sound travels at 343 m/s and when there is major temperature change that speed changes "
] | [
"Technically, yes. In actual practice, you probably wouldn't hear much difference here on Earth. The most amount of difference you might hear is a very humid day compared to a very dry day. The humid day would sound slightly more \"muffled\", but it would be really hard to notice it.",
"I can not tell you about o... | [
"The overtones are inherent in a single note. Playing multiple notes doesn't make them appear, it just makes them more noticeable when two notes have overtone series that overlap. "
] |
[
"If you're driving down hill with your foot off the gas pedal, is your car still using gas?"
] | [
false
] | null | [
"Could you please elaborate on how you can shut off fuel injectors completely and still keep the engine running. I need to know this because right now it doesn't make any sense to me.",
"As far as I know, if the TAC is registering anything above zero rpms... pistons are pumping and fuel is being ignited. Zero rpm... | [
"For a traditional internal combustion engine, it will depend on your transmission. Most manual transmissions and dual clutch automatics will shut off fuel injectors completely when costing in gear -- thereby using no gas. A slushbox automatic, on the other hand, might not be able to transfer enough torque back to ... | [
"For a traditional internal combustion engine, it will depend on your transmission. Most manual transmissions and dual clutch automatics will shut off fuel injectors completely when costing in gear -- thereby using no gas. A slushbox automatic, on the other hand, might not be able to transfer enough torque back to ... |
[
"Why do quarks have electric charge which is multiple of 1/3 (and not, for instance 1/5?)"
] | [
false
] | null | [
"Actual answer: they just do. Nothing forbidden about 1/5, nothing special about 1/3.",
"Also actual answer: there is something ",
" special about 1/3, which is that the Standard Model must satisfy something called 'anomaly cancellation' conditions in order to be mathematically consistent. This puts non-trivial... | [
"Sure, but the ratio of quark charge to electron charge would still be 1/3(or 2/3) independent of the units you use."
] | [
"In the standard model it is just placed there by hand, but isn't a choice and is required for the reason given by ",
"/u/nonabeliangrape",
" ",
"Also actual answer: there is something somewhat special about 1/3, which is that the Standard Model must satisfy something called 'anomaly cancellation' conditions ... |
[
"Why does standing water evaporate?"
] | [
false
] | [deleted] | [
"The temperature of a liquid like water is proportional to the average kinetic energy of the molecules. The key word is \"average\": In fact the molecules have some distribution of energies (i.e. some are moving slower, some faster). This means that near the surface of some water there is always a small number of p... | [
"In a sealed container, a small amount of water will evaporate to maintain a certain ",
"vapour pressure",
" in the air that depends on the temperature. Eventually, this will reach equilibrium, and even though it's below the boiling point, some of the water still manages to escape the liquid into the air, but t... | [
"In evaporation, the surface molecules of the body of water are the ones to vaporize. Even in water well below the boiling point, there is still a considerable amount of energy contained within the molecules. These molecules obtain sufficient energy through the kinetic energy of the water molecules, or energy trans... |
[
"Why do f-holes in instruments such as violins and cellos produce a superior sound/tone?"
] | [
false
] | I always see this as a benchmark for the quality of the instrument, and am very curious as to why | [
"Physicist and guitar/cello player here. The exact shape of the f-holes does not matter too much. There are many variations which however do not affect the sound of the instrument too much. However, there is an important difference between the round sound hole and the f-hole. Guitars are built with both variations ... | [
"The shape of the hole is almost purely decorative, the \"f\" shape being traditional for the viol family (violin, viola, cello).",
"Basically, the shape doesn't matter as much as the fact that there is a hole."
] | [
"Thank you for that lesson about the archtop. I'm a multi-genre violist who is now playing bass in a local college jazz band. (Bass Guitar, I cheated, tuned it to cello strings. Now I mildly regret it because I can't easily switch to standup bass for jazz sound.)",
"I hadn't understood the difference between volu... |
[
"Why do we stretch our muscles right after waking up?"
] | [
false
] | null | [
"Doesn't the brain also release a mild paralytic in order to keep us from injuring ourselves during active sleep cycles?"
] | [
"Doesn't the brain also release a mild paralytic in order to keep us from injuring ourselves during active sleep cycles?"
] | [
"It's called pandiculation. Most mammals (or vertebrates perhaps?) do it, which suggests it's a deep neurological reflex. Nobody is entirely sure why, and as is plain from this thread, guesses are just that: guesses.",
"On mobile, apologies for lack of references. Go to Google scholar and type in pandiculation fo... |
[
"What does it mean when we say that vaccines contain \"dead viruses\"?"
] | [
false
] | I got a flu shot today, a "trivalent inactivated influenza virus vaccine injection". According to the pharmacist who administered it to me, this means the viruses in the vaccine are "dead". Viruses, as I was taught in high school Biology, are not "alive" in the traditional sense. Or at least they straddle a line between alive and not. So how exactly are they "killed" to be put into vaccines? And what happens to the individual viruses when that happens that we consider them "dead" at that state? | [
"They're typically heat-killed, which denatures the viral proteins and prevents them from completely hijacking your cells as a normal, non-damaged virus would. Some vaccines don't even contain the whole virus, but just the proteins, which is enough to inoculate you."
] | [
"The whole \"killed\"/\"dead\" thing about viruses is just words; it has no biological significance. Viruses are obviously capable of replicating and causing disease, and the debate about what to call that is just about the word to put on it, not the biological fact.",
"A killed virus vaccine is a vaccine made o... | [
"You can test some vaccines by taking aliquots and lining a monolayer of cells and checking for certain parameters (e.g. cell death for lytic cells, certain biomarkers or metabolic measures for lysogenic viruses).",
"The immune system is strongly reactive to foreign proteins (not but so much sugars) so testing fo... |
[
"Why doesn't diarrhea kill us when it used to be so fatal?"
] | [
false
] | When we get diarrhea, we generally don't take medicine for it & we don't die from it. Why was diarrhea so fatal back in the day? | [
"It wasn't diarrhea that was fatal. Dysentery and other illnesses whose symptoms include diarrhea were fatal. In modern days, most cases of diarrhea are symptoms of mild digestive irritation, poisoning, or psychosomatic disorders. The lethal cases you refer to from the past were symptoms of much more serious afflic... | [
"Two important factors ",
"1) we are better at treating cholera, a bacterial disease that kills through dehydration caused by severe diarrhea. It used to kill people in the millions. ",
"2) this is the important one, we discovered a very important mechanism in the gastrointestinal system. Water absorption is a ... | [
"Don't be afraid of it unless you've recently been downwind of a nuclear fission weapon detonation."
] |
[
"How pronounced is the \"classical Casimir effect\" experienced by ships that are docked close to each other?"
] | [
false
] | [deleted] | [
"He's talking about water wave modes between ships, not actual electromagnetic Casimir forces."
] | [
"According to ",
"Nature",
" it's mostly just an urban legend.",
"This article",
" may go into greater detail but I ",
" haven't read it yet."
] | [
"No, this is just due to air pressure, similar to a suction cup."
] |
[
"Can we replicate a Pool break in perfect conditions?"
] | [
false
] | [deleted] | [
"Part 1: Yes, a computer would be able to simulate the same break over and over pretty easily. Keep all the variables and math the same and you will keep getting the same outcome.",
"Part 2: I could write a really long winded answer about chaos theory and computational/technological/practical limits, but rather I... | [
"No- Sensitivity to initial conditions would prevent this from happening. ",
"You may know the position and velocity of the ball to so many decimal places, but you do not know it past that. You can not measure its position and velocity exactly. And since you do not know these exactly the divergence between act... | [
"I'm skeptical. It seems like the mass of the balls makes them much less sensitive to initial conditions. And I suspect that the balls can be reliably placed in a well-established initial configuration (e.g. by rapping the balls into the felt, ensuring that they're all touching, etc.). Finally the break could be... |
[
"Does Radioactive Uranium actually hum?"
] | [
false
] | null | [
"We need more context, but a piece of uranium just sitting by itself doesnβt make any noise."
] | [
"The guy i was talkin thing to said they had \"depleted uranium fuel rods on a conveyor belt\" thats all i got sorry"
] | [
"Well I donβt see why the uranium would be βhummingβ in that situation."
] |
[
"How do we know the age of the universe, specifically with a margin of error of 59 million years?"
] | [
false
] | null | [
"There's a phenomena called the Cosmic Microwave Background, or CMB. If you point a radio telescope in any direction, you see radio waves from the CMB. Looking at radio waves from the CMB is kind of like looking at visible light from the sun. If you go far back enough in time, the universe was denser and hotter, so... | [
"dark matter is the phenomenon that many galaxies should have flown apart instead of rotating (if they only have the mass of matter we see). So there must be another source of gravity, and we call it dark matter. (dark cause we can't see it and matter, cause that has gravity) Just keep in mind, that is just a name,... | [
"Great explanation; thank you. About your side note, does it explain dark matter or dark energy? Isn't dark energy what's used to explain the expansion of the universe? I would think that would be implicated more w changes in the CMB. "
] |
[
"Why can't human nerve cells regenerate?"
] | [
false
] | I know that some of them can do it, but the most aren't able to. So is there any good explanation for it? Wouldn't we better of with regeneration? | [
"\"Wouldn't we be better of with regeneration?\" is the wrong way to go about this. Those cells evolved, so they do not necessarily have to behave in the optimal way.",
"Then again, the balance between regenerative powers on one side and the danger for uncontrolled regeneration and multiplication has to be mainta... | [
"Great anwser, thank you. Do you know any papers/books about the connection between reeneration and cancer?\nI also was thinking that, possibly, bran cell regeneration would erase our memories. What do you thing about that?"
] | [
"Just learning about this now, but since there is a dearth of answers i'll give it a shot. ",
"Cells in your peripheral nervous system and central nervous system have different helper cells that keep them nourished and supported structurally among other things, but the specific helper cells are different. The one... |
[
"How does gene editing lead to changes throughout the body?"
] | [
false
] | null | [
"Hi joechoj thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the followi... | [
"Medicine"
] | [
"Medicine"
] |
[
"What exactly is the sine function? What does it do to the number in the brackets?"
] | [
false
] | I understand that a sine wave represents the relationship between the Cartesian coordinates of a point on a circle's edge, and the angle of the point. I know that, by combining a sine and cosine wave, you can draw a circle. I know the whole reason the sine wave is shaped that way is because a circular curve first drops slowly at the top of the circle, then very steeply, then slowly again. And from what I understand; in maths and programming, a function is just a set of instructions. It's short-hand for a list of operations to be performed on whatever you put in the brackets. What are these instructions for the sine function? Is it complicated? I suspect it somehow involves Pi or e or some other crazy number. Or - on a computer - does the sine function actually just reference a pre-made curve of data representing a sine wave? | [
"A function is not a list of instructions. A function from a set A to a set B is nothing but an assignment of a single element of B for every element of A. Sometimes the assignment is explicit and we can use it as a list of instructions to calculate things. For instance, if I have a function that assigns to every r... | [
"Yes, but you can't do it forever. At some point you must stop. The upside is that if you want to calculate sin(x) to within an error is just epsilon, then you know that if you go out far enough, you'll eventually always be within epsilon of sin(x). This is the whole epsilon-delta nature of limits. All limits are j... | [
"I see where OP may be a bit confused.",
"In programming, as OP mentioned, a function ",
" a list of instructions, roughly. This is unrelated to the mathematical concept of a function. Same word, two very different things."
] |
[
"Does Earth's annual tilt that creates summer and winter affect geostationary satellites?"
] | [
false
] | null | [
"No, the tilt of the axis doesn't shift (well it does but over hundreds of thousands of years, but for this purpose it doesn't).",
"The seasons are caused by the angle of incidence of light hitting Earth as it orbits the sun, the tilt doesn't change at all. So geostationary satellites are fine. "
] | [
"I can't remember what the phenomenon is called, but at certain times during the spring and fall the satellite and the sun will be in the same position in the sky which will cause interference."
] | [
" satellites orbit on the equatorial plane. This is inclined about 23Β° relative to the ecliptic (the plane of Earth's orbit). Their orbit is at an altitude of ~36000km (radius ~42000km), so Earth looks relatively small from that distance.",
"Thanks to the distance and the inclination, they get constant light on t... |
[
"How do we know Virus \"X\" lingers in the air for \"X\" hours?"
] | [
false
] | For example. They say COVID19 can remain in the air for 3 hours. How do they figure this out ? | [
"Covid19 is a corona virus, like SARS, MERS and a variety of other less well know viruses we've seen before.",
"Although technically the virus is called SARS-CoV-2, where COVID-19 is the name of the disease it causes. Yes, I'm moderately fun at parties."
] | [
"Covid19 is a corona virus, like SARS, MERS and a variety of other less well know viruses we've seen before. So early in the life cycle of something like this they base it on research done with those known, similar viruses. We also have a lot of data on sneeze/cough droplet spreads and the like that will apply to j... | [
"Hey I'm a fan of factoids, we can sit in the corner and be lame together."
] |
[
"Would the force of gravity be weaker on the side of the moon facing Earth?"
] | [
false
] | For example: if I was standing on the near side of the moon and jumped, would I jump higher than if I were to perform exactly the same jump on the far side of the moon, because of Earth pulling me away from the moon? I hope this is worded clearly enough to understand. Thanks in advance. EDIT: Wow, thanks for the in-depth answers guys! | [
"In theory, something very similar to what you asked would happen, but not strong enough to even notice.",
"Gravity would feel weaker in both the near side and the far side of the Moon. It would feel stronger on other parts of the Moon, perpendicular to the Earth-Moon line. This is due to ",
"tidal forces",
"... | [
"Tidal forces are not caused by the orbital motion of an object (which implies that a tidal force is really the centrifugal force). Rather, tidal forces are caused by the gravitational gradient. If the moon was not orbiting the earth, but was held in place at its current location, the tidal forces would be exactly ... | [
"This is a common misconception that even creeps up in textbooks. The tidal bulge on the far side of the earth is not caused by centrifugal force. It is caused by the elongating effect of gravitational gradients. The textbook Planetary Sciences by Pater and Lissauer covers this on p.40:",
"http://books.google.com... |
[
"What form is hydrogen in stars?"
] | [
false
] | So everyone pretty much knows that stars are made of hydrogen mostly, but like what form is the hydrogen in? Just elemental hydrogen, 1 proton 1 neutron 1 electron? Or an ion/isotope? I would assume it's probably an ion due to my very basic understanding of how plasma works but specifically what form is the hydrogen? | [
"You are correct to think that you're dealing with ions, of course a hydrogen ion is just a proton, which is where stellar fusion begins with the proton-proton chain. The steps are",
"p + p -> ",
"H",
" (deuterium nucleus) + positron + neutrino",
"H",
" + p -> ",
"He",
" (helium-3 nucleus)",
"He",
... | [
"ah thats helpful. so where do all the electrons go? "
] | [
"Since they're in a plasma the electrons are free, they aren't part of the reactions"
] |
[
"Is it possible to limit the impact of a tsunami by sending out waves in the opposite direction?"
] | [
false
] | I don't know if it's possible to do this once the wave has already started because I know the tide goes out considerably when a large wave develops. | [
"No, because even if yo could get the waves perfectly in phase, at one point, the waves are radial, not in a straight line, so you couldn't stop them everywhere, your created wave would do damage elsewhere.",
"Thats ignoring the obvious, in order to make a wave that powerful, you'd have to release the same energy... | [
"Making a wave in the opposite direction does not work, there would only be a small amount of interaction between the incoming tsunami and the outgoing wave. To absorb a wave you need to make a wave in the ",
" direction, but with opposite phase.",
"Basically the only way to limit a tsunami is to put a lot of s... | [
"True, globally the tsunami wave is radial. I think a corollary question is whether one could limit the impact of a tsunami locally - many people would be interested in limiting the impact near one point, e.g. one city or one nuclear plant. At this point, the waves are planar. Cancelling waves locally wouldn't r... |
[
"How are the compositions of Asteroids determined?"
] | [
false
] | I know a little about asteroids, like how we use "spectography" in order to say what an asteroid is made of. I'm curious how this process actually works. How does seeing the color and wavelength let us determine what the asteroid is made of? Also, isn't this essentially just telling us what is on the outside? How could we know what is inside the asteroid? Surely an asteroid is not simply a homogeneous mass of the same mineral. | [
"The wavelength of light that you are looking at reacts differently to different types of substances. That is inherently down to the interactions of the light itself with the atoms of the substance that the asteroid is made up of. For eg, a certain part of the spectrum that you see from an asteroid may be enhanced ... | [
"Different compounds reflect different wavelengths of light. This will tell you the chemical makeup on the surface, though it looks like this was already explained fairly well. ",
"As for the inerior.... There is no immediate way to determine the composition on the interior of the asteroid. But there are some w... | [
"Interesting, I wouldn't have guessed that asteroids had a homogenous mass distribution...",
"Would that mean then, if someone were to sample the interior of an asteroid, it is likely the rest of the asteroid is of a similar makeup?"
] |
[
"Do blind people experience the ganzfeld effect?"
] | [
false
] | Would a blind person experience the visual hallucinations prompted from seeing nothing but a black field? (Specifically, someone who is blind due to damage to the eyes and photoreceptors not the cortical visual systems) | [
"I think this has been answered before in another Reddit thread.",
"This article summarizes a 1964 study where totally blind patients were given LSD (those were the days when such a study was not unethical. Ahhhh sigh).",
"Subjects who were blind, but had visual information at some point or another, did experi... | [
"I'm curious how you know for sure that a fully blind person is or isn't having visual hallucinations if they've never seen anything before. How do you explain vision to someone without functioning eyes"
] | [
"Yes, there is a very similar phenomenon known as the ",
"Charles Bonnet syndrome",
". In the absence or diminishment of visual stimuli, the intact visual cortex of the brain will sometimes come up with hallucinations. Classically, the hallucinations are lilliputian and often cartoonish (",
", one might see a... |
[
"What would happen to a plane if, instead of leveling out, it simply continued to ascend towards space?"
] | [
false
] | Found myself wondering this as my flight took off yesterday. Example questions: *how high would the plane get before the engines failed? *When would the plane explode (if at all)? *Would it just keep going up into space if it were going fast enough? and if so, how long before conditions on-board killed all passengers? | [
"Planes use the air around them to produce lift, and the less dense the air is the less lift they can produce at a given speed. If a plane attempts to climb indefinitely, it will eventually reach a point where it can't produce enough lift to overcome gravity, and will cease to gain altitude.",
"Would it just keep... | [
"Any plane will have a ",
"service ceiling",
" which is the maximum altitude it can maintain stable flight (you might be able to accelerate lower and then \"jump\" above this level but you will inevitably fall back down). In the normal case, it is caused by less lift from less dense air ",
" less lift from le... | [
"very interesting. thanks for the reply!"
] |
[
"Why does the roof of my mouth burn so easily?"
] | [
false
] | I've often wondered why it is the case that the roof of my mouth burns easier than any other part of my mouth. Sometimes if I accidentily take a sip of a hot drink and it's burning I'll lower my mouth so it's on my tongue or near the back of my throat to stop the burning, usually it is too late. It seems areas like the throat, tongue and cheeks are all more resiliant to hot foods and drinks than the roof of the mouth which seems counter-intuitive as the roof of the mouth is the area the food tends to hang around while it's chewed up and cooled down. | [
"Any useful reason why this is?"
] | [
"Any useful reason why this is?"
] | [
"Uh, no."
] |
[
"Why are there no saltwater amphibians?"
] | [
false
] | null | [
"There is one saltwater amphibian: the crab-eating frog. According to Wikipedia, adults can survive in water with up to 2.8% salinity, while tadpoles can survive in water with up to 3.9% salinity. For reference, the largest oceans average about 3.5% salinity.",
"The crab-eating frog has evolved some amazing kidne... | [
"No, that's crazy we never came from monkeys. ",
"What I'm saying is, it's equally possible for life to have originated in Salt Water despite there not being many salt water amphibians today. The salinity of the water could have been the catalyst for amphibians to move onto land primarily. The fresh water amph... | [
"So, if all land life evolved from amphibians, that means it evolved from freshwater fish. And that might mean that land life evolved from a single body of fresh water. Interesting."
] |
[
"Would a corpse decompose in outer space, or say the surface of the moon, as it does on Earth?"
] | [
false
] | I remembered this scene in Kubrick's adaption of 2001, where HAL kills the astronaut working on the outside of the craft and his body is shown drifting further into space. Would his body decompose over time, while he's in that suit? Would it change if his body were not protected by a space suit? | [
"No the body would dessicate and mummify, similarly to what happens to corpses at very high altitudes. Decomposition is mediated by bacteria which cannot live in a very low pressure, low temperature environment. Even if the integrity of the suit were maintained, temperature would drop below freezing quickly and all... | [
"The process of decomposition is a direct result of bacteria inside our bodies breaking down our body into its constituent components, so yes his body would decompose but only to a point, as the heat produced by the decomposition would be slowly lost through the space suit and the bacteria would freeze to death eve... | [
"On an interesing but unscientific note, the fourth book in the series, 3001: The Final Odyssey, is written completely on the premise of what happen to Frank Poole after HAL throws him off into space. ",
"Ice miners discover his body and are able to revive him and thats where the book starts. "
] |
[
"If all atoms of a given element are equal, what causes one atom of the element to radioactively decay before another?"
] | [
false
] | null | [
"Random chance. Two nuclei of the same type, in the same state have the same half-life. The half-life is related to the average time it will take the nucleus to decay. Almost definitely, one will decay before the other. Which comes first is just random chance."
] | [
"Put another way, you could say \"what number comes up on a die is random chance, with a 1/6 probability for each outcome.\" However if you pay attention to all or control all of the mechanics of each toss, you can accurately predict an outcome or explain why a certain number came up instead of another. It's just ... | [
"However if you pay attention to all or control all of the mechanics of each toss, you can accurately predict an outcome or explain why a certain number came up instead of another.",
"The mechanics of a dice throw is classical; the mechanics of a radioactive decay is quantum. Even if you have 100% knowledge of th... |
[
"How is the jump made from unicellular organisms to multicellular organisms, and how does specialization of functions occur?"
] | [
false
] | I was trying to explain evolution, but got stuck on this early phase of life - I realized I couldn't fully explain it. Can help me out? | [
"There are lots of theories, some good, some bad. The one I lean towards currently is biofilms.",
"Biofilms are complex communities of bacteria. They can be single or multispecies (the crap on your teeth in a multispecies biofilm, for example). I'll stick with single species because they're simpler. ",
"Take on... | [
"This was incredibly helpful and interesting. But since you seems to have a good grasp of the topic, care to elaborate on some of the other theories? Even the bad ones, as long as you state why they're bad."
] | [
"wow, thanks. for a gross over simplification, that was pretty enlightening!"
] |
[
"What happens when you have an organ surgically removed?"
] | [
false
] | [deleted] | [
"The organs aren't well packed at all. They're vacuum sealed and your standard human is organised the same as everyone else, but a lot of the time that structure isn't necessary. So if someone has some sort of bowel surgery, the surgeons will generally just shovel the guts back in, sew 'em up and let them get on wi... | [
"Medical student here. This is spot on. In addition, the body will also form scar tissue that tends to fill the space. Just opening the abdomen can cause adhesions and scar tissue. "
] | [
"Yes. This is particularly important in the thoracic cavity (the one that's full of lungs)- when you open the chest, the lungs collapse to about the size of a tennis ball, and the only way to reinflate them is to close the chest and suck the extra air out."
] |
[
"Would a creating artificial gravity through a centrifuge impact something like a watch's time over a period of time?"
] | [
false
] | If someone had 2 very accurate clocks and one was placed in a centrifuge to create strong artificial gravity, would the clock in the centrifuge eventually be measurably ahead of the other one? | [
"The clock in the centrifuge would measure behind the other one. If you observe the system in the external frame, the time dilation observed for the centrifuge clock is equivalent to that predicted by special relativity.",
"If you're in the centrifuge, the time dilation experienced would appear to be due to \"gra... | [
"That's really strange. What about the differences between GR and SR? For example, in SR, if a person moving at some velocity close to c observes a clock in a frame that is stationary relative to him, the clock appears to tick very slowly. If the people in that stationary frame observe a clock in the fast-moving pe... | [
"For example, in SR, if a person moving at some velocity close to c",
"Relative to what?",
"observes a clock in a frame that is stationary relative to him, the clock appears to tick very slowly. ",
"Any clock stationary relative yourself ticks at the normal rate. Did you mean observes a clock that is moving v... |
[
"Does multi-verse theory allow for variation in the laws of physics or must the laws of physics be constant across all universes?"
] | [
false
] | null | [
"Which multiverse theory are you talking about ? The idea that there could be many possible universes (yes physics can change) or the Everett many worlds hypothesis of quantum theory (in which case locally the laws should be the same)",
"Of course there is nothing in principle stopping some laws (e.g. involving t... | [
"What about mathematical constants that are more abstract, such as Ο or other mathematical/ geometric properties/constants "
] | [
"There are several multiverse theories, but in all of them I am aware of, physical constants could vary. ",
"The catch is that you can only exist to observe them in a very select subset of those variations, so from your point of view as an observing agent, the laws of physics would be constrained to those which ... |
[
"Any idea what's going on with the sun in this picture?"
] | [
false
] | Yesterday (Sunday) in Atlanta, GA, we were walking through the parking lot to the Braves game and everyone was staring up at the sky, taking pictures. There appeared to be a giant circle around the sun, and nobody had any idea what it was. Any idea what it is? What causes it? | [
"This is a ",
"22 degree halo",
". It's an optical phenomenon caused by ice crystals in the atmosphere. If you hold your arm outstretched with your hand giving a 'hang ten', the span between the tip of pinky and the end of your thumb will measure about 22 degrees."
] | [
"I am not a meteorologist. But I believe those are ice crystals in the upper atmosphere doing that. Here are at least the images google turned up with that search ",
"http://www.google.com/images?rlz=1C1CHMP_enUS291US304&q=ice%20crystals%20around%20sun&um=1&ie=UTF-8&source=og&sa=N&hl=en&tab=wi"
] | [
"Sun dog refers to the spots of light on the sides, not the halo itself."
] |
[
"Curious about evolution, mind vs body"
] | [
false
] | I have a question about human evolution that seems to me to resemble the old adage of the chicken and the egg. Would the human brain have evolved first and "built" a body to defend it or would the "mindless" body have evolved a mind to allow it to hunt/gather more effectively? | [
"Well you could say that the body developed first, since single celled organisms didn't have a nervous system (which is what the brain is part of). But the question doesn't make a lot of sense since they developed together."
] | [
"You can't will evolution. I'm not 100% what you are asking but from what I can tell you are asking if \"humans\" got being brains then selected on their own to stand up right and all that. ",
"If you look at early hominids you can tell they stand up right long before they use tools."
] | [
"Well first of all no complex animal is \"mindless.\" Our brains differ from other mammals only by degrees, not by some really fundamental divide, even if the difference in capability is large.",
"Evolution works on the whole creature, and so mind and body are always going to be evolving as a combined unit. I su... |
[
"If pi is an infinite number, nonrepeating decimal, meaning every posible number combination exists in pi, can pi contain itself as a combination?"
] | [
false
] | null | [
"[edit: As pointed out by CAPS_LOCK_LIAR, I didn't actually explicitly answer the question. The answer is \"no.\"]",
"First, the fact that the decimal expansion of pi is infinite and not eventually repeating does ",
" guarantee that every possible number combination exists within that expansion. It doesn't even... | [
"For an example of a decimal that is infinite and not repeating, consider",
".101101110111101111101111110...",
"While it's clear how to continue the pattern, it never actually repeats. And clearly it will not contain all sequences. So this is not a normal irrational."
] | [
"If the digits DID start repeating, then you could write pi as a rational number, i.e. a/b for some a and b.\nHere are the \n",
"proofs that pi is irrational",
"."
] |
[
"How does my cat not die/get electrocuted when he chews through my power cords?"
] | [
false
] | My cat chewed through his 10th power cord today. I always figured since his tongue was covered with saliva (which I think is conductive) he would get a shock. Can anyone explain to me why this happens? | [
"If it's between the adapter (brick) and the computer, it's not wall-voltage. That brick's job is to take wall voltage and step it down to DC low-voltage that the laptop wants. So - the cat is chewing through what amounts to a few AA batteries for voltage, and low current. You'd get a nastier shock from li... | [
"Sorry but this is really incorrect...on all accounts. While the 3 phase power into an american house is capable of supply 240vac, the outlets in your wall only have a maximum potential of 120vac. There is a ground wire and a black/white pair, black is hot (120vac) wrt to white and white is neutral. At the panel... | [
"if you watched her like a hawk, wouldn't you have to capture and eat her?"
] |
[
"How does space have a temperature if it's just vacuum?"
] | [
false
] | null | [
"Remember that \"temperature\" is a pretty handwavey concept. We can't measure temperature directly. We can measure ",
" in temperature, by seeing how something metallic expands or contracts over time for example. Or we can measure the radiation coming off an object and make a guess as to its temperature based on... | [
"Layman here. My terminology is probably all wrong.",
"When people talk about the temperature of space, they're talking about the ",
"cosmic microwave background radiation. (CMB)",
" This is a persistent microwave 'buzz' with a peak frequency of 160.2GHz or a 1.9mm wavelength.",
"All material will emit elec... | [
"This ",
"BBC-Horizon",
" episode provides a vary interesting explanation for what ",
" means."
] |
[
"What does an imaginary factor of a polynomial represent?"
] | [
false
] | [deleted] | [
"By themselves, they don't mean anything. But if your quadratic equation models some sort of real-world scenario, then the roots refer to something in that scenario.",
"If a quadratic equation is the path of a projectile thrown into the air, then the solutions might tell you where the projectile was launched and ... | [
"I don't know what kind of answer you are expecting. They are solutions just as a valid as one with only real numbers. So if you calculate 2*(1.5+0.5i)Β² - 6 * (1.5 + 0.5i) + 5 you get 0. Same for the solution with the minus. Maybe you should look at it from a graphical side. Create a coordinate system in which the ... | [
"Thanks, this is pretty cool"
] |
[
"Microwave Ovens: What is the relationship between the power level selected and the cooking time?"
] | [
false
] | Serious question...I'm wondering about the science behind this relationship, and how it affects the product being "cooked" if different combinations of power and time are selected. Say I place a cup of water in the microwave. In one instance I select full power and 1 minute cooking time. If in another instance I select 50% power and 2 minutes cooking time, would I get the same result with the cup of water (same ending temperature of the water, etc)? Why or why not? I'm assuming there must be a difference, as modern microwave ovens have a separate "defrost" setting you can select, which I assume has something to do with using a lower power setting over a longer time period. I understand that the microwave "cooking" energy is (generally) applied to the water (fluid?) content of the item being cooked. And for my question, I am assuming the same output wattage microwave oven is being used (ie - 1100 watt, etc). PS - Not sure if I should use the Physics or Engineering "flair", so I submitted as a Physics question. | [
"There are a variety of factors to take care of, so I'll try my best to explain:\nAdmitting your microwave has a power of 1'000 W (watts). It means it delivers 1'000 j/s (joules/seconds) at 100% power setting. For the sake of explanation we'll assume every joule is used to heat whatever is in.",
"So, if you have ... | [
"Really, the main reason is that its way easier and cheaper to have a magnetron that just turns on and off rather than changes its output power."
] | [
"What you're asking for is called diffusion; I'll try to explain the differences.",
"Convection is a natural mouvement that occures when there are multiple states of mater in a given medium (difference in temperature, difference in concentration). For temperature: imagine molecules like small balls, if they're ho... |
[
"Is there any way for a planet to have seasons that vary in length from year to year?"
] | [
false
] | Watching Game of Thrones where the winters and summers always last different lengths of time got me wondering if this is actually possible. Is there a conceivable way that a planet could allow for this? Whether its orbit be disturbed by another planet in some way or whathaveyou? | [
"I think GRRM has said that it's due to magic and not astronomy, but it could happen if the planet was in a highly eccentric elliptical orbit with another large object orbiting the same star.",
"This paper discusses it in more detail: ",
"http://arxiv.org/pdf/1304.0445.pdf"
] | [
"Seasons are caused by the tilt of the axis of rotation and the amount of solar energy the surface receives. So a planets axis tilt would also have to wobble in semi stable way.",
"I'll defer to a real expert on the matter, but one theory I could come up with would be a planet with 2 very large moons having diffe... | [
"Well, notice 1) the publishing date along the side, and 2) it's not actually in a peer-reviewed journal, but rather submitted to arxiv (a clearinghouse for scientists to submit papers that are still in review). It's actually pretty common for folks to submit \"joke\" papers to arxiv on that date."
] |
[
"Is it possible to completly solve chess?"
] | [
false
] | I donΒ΄t mean just programming an engine that is able to beat anyone. I mean to have a computer calculate the best turn (assuming that there always is exactly one best turn) in all possible position and storing the result as a file, so that another computer would have to do nothing but searching for the current position to know the best turn. And if it is possible, how long would it take the currently fastest computer to do so? | [
"Mathematically, yes. Realistically, no. While it's a finite number, there are many orders of magnitude more chess games possible than there are atoms in the universe. It's not physically possible for a computer capable of storing those games to exist, due to lack of available matter if nothing else.",
"https://e... | [
"Building off of this, chess endgames have been solved for all possible positions for up to seven pieces on the board. ",
"https://en.m.wikipedia.org/wiki/Endgame_tablebase"
] | [
"u/eterevsky",
" is correct. It is sufficient to find an algorithm that can tell whether a given state relates to 'A can force win' ,'B can force win', or 'draw'. ",
"This algorithm ",
" be a comparison with a large database containing all states. "
] |
[
"How do scientists discover new complex molecules?"
] | [
false
] | null | [
"I work in a lab that focuses on specialized metabolism in plants. Theres a number of things you can do for this.",
"For one mass spectrometery is pretty amazing these days. We can have mass spectrometers get insanely accurate mass measurements, well below a dalton and if done properly you can get some interestin... | [
"I canβt speak to the process involving naturally occurring molecules, but I do have some experience in high throughput screening methods which are used extensively in pharma and formulation science. Typically a combination of high accuracy calculations and machine learning techniques are used to identify potential... | [
"The type of compound you're describing sounds like what chemists would categorize as \"natural products\". Usually there is anecdotal evidence that a certain plant, critter, or whatever causes some sort of medicinal benefit. It's quite common for the \"active ingredient\" in these sources to be quite potent, that ... |
[
"It is theorized that diseases like IBS are caused by bacterial dysbiosis, so why doesn't the immune system eliminate the offending bacteria and prevent them from colonizing the GI tract?"
] | [
false
] | To clarify my question as advised: | [
"There are cells called Tregs (regulatory T cells) that direct the immune system to ignore certain antigens, including those of gut bacteria. The immune system wouldn't know to attack \"overgrowth\" of gut bacteria, because they're already in a protected class of citizen, so to speak."
] | [
"Tregs are a somewhat new (last twenty years) discovery, and they're mostly being manipulated to try and decrease autoimmune diseases right now, at least that I know of. The issue here is that the immune system needs to be able to distinguish between \"self\"/\"protected\" and \"non-self\"/\"non-protected\" antige... | [
"While the GI tract plays a huge role in the immune response, the immune response in the \"gut\" is generally setup to keep pathogens from entering into underlying tissues and the blood. Your GI tract is the one place we to stick foreign antigens (in this case food) and not generate an immune response. Your GI syst... |
[
"Can you build Nuclear Weapons from a light-water reactor?"
] | [
false
] | I was reading a wiki the other day where the United States came to a compromise with North Korea (over a decade ago) regarding nuclear energy. North Korea wanted to pursue it for "energy" purposes, so instead, the United States offered to build a light-water reactor there instead. I would assume there would be little to no supervision outside of the occasional UN visit. Could you build nuclear weapons from LWR? Is there a viable reactor we could build in countries that is a good source of energy, you can't build powerful weapons from, and don't need supervision? I am creating a (fictional) policy on how to attack climate change from the perspective of the U.S. | [
"Anytime you have a process that involves neutrons, you have the capability to create plutonium. This includes light water reactors. ",
"That said, you need to be constantly removing fuel and separating the Plutonium, which requires complex reprocessing centers. You also need enrichment centers to bring the enric... | [
"Like ",
"/r/Hiddencamper",
" mentioned, you can use a LWR to \"breed\" weapons grade materials. Neutron fluence in the reactor core slowly transmutes the fuel from uranium to plutonium, but it's stuck in the fuel with everything else. To isolate it you have to use rather complicated processes that are difficul... | [
"Thorium reactors have different proliferation risks. The fissile material in a thorium reactor is Uranium 233, which is produced by breeding from the thorium. U233 is better than U235 for making weapons, and because it can be separated from the thorium by simple chemical processes is much easier to acquire from ... |
[
"Why do we get that tingling feeling in our legs?"
] | [
false
] | Sometimes after sitting for a while my legs 'falls asleep' and it takes a while to stop 'sleeping'. what happens in your body when this happens? what is the cause? how can i prevent it from happening again? | [
"Nerves. "
] | [
"'Paresthesia' is the medical term for the \"pins and needles\" feeling. It describes the partial numbing of a nerve. \nSide note: Many people are familiar with the similar word 'paraplegia'. This describes a completely numb nerve, IE: He cannot walk because he is paraplegic.\nParesthesia can be caused by pinching... | [
"very interesting.\nso relatively speaking because of the electric currents not being passed through the bodies in paraplegic that is why they are unable to move? if so how come for some of these unfortunate people is it not possible to 'jump start' the electric currents so that they can move again?\nor i am unders... |
[
"Can a person lose fat cells or do they just change in size?"
] | [
false
] | When a person loses weight does their fat cell count decrease or does the size of the cells decrease? | [
"A bit of both depending on the age, but mostly its the fat content not the cell number than changes. Adults tend to keep the same number of cells and just change how much fat is stored in them. The number of fat cells in children can change until we reach about 20 years old, then that number is locked in",
"http... | [
"A little late, but Iβve always been curious (if this is true) how liposuction would impact future fat deposition..."
] | [
"Usually the amount of fat cells remain the same and the size just decrease with regular dieting methods but if you were to do liposuction then the fat cells would get reduced since the doctor is actually taking out the fat cells."
] |
[
"Are gravitation and time dilation indistinguishable minus an external observer?"
] | [
false
] | [deleted] | [
"None of this makes any sense. Can you please rephrase the question in a way that doesn't involve elaborate hypotheticals or drugs?"
] | [
"Sure, there is a ship moving next to a black hole, as it passes the black hole, the ship will experiencing itself turning towards it.",
"Alternatively, a ship has two engines on each side of the ship that each spit out one ion per second from their respective reference frames. They are experiencing some kind of... | [
"They are experiencing uneven time dilation",
"This would not happen. The only way that could happen is if different parts of your hypothetical impossible rocketship are accelerating at different rates."
] |
[
"Defibrillators almost always work in the movies. How likely is it to actually work when your heart stops in real life?"
] | [
false
] | null | [
"Paramedic here: The chance of a defibrillator working is directly proportional to amount of of time that elapsed since the heart has gone into fibrillation. ",
"Defibrillators are not used in Asystole (flatline) but in Ventricular Fibrillation (heart still quivering), and Ventricular Tachycardia (fast ventricula... | [
"A defibrillator isn't for cardiac arrest, it is for fibrillation, which is when the heart instead of contracting in the normal way begins to spasm causing it to stop pumping blood. A defibrillator sends a sudden shock through the heart, the hope is it causes a reset and the muscle begins contracting in an orderly ... | [
"The long answer is that it depends on why your pulse stopped.",
"If the heart has literally stopped all activity, showing a \"flatline\" on the EKG, the condition is called ",
"asystole",
". The defibrillator has no effect on asystole and will not be used. The only response is to continue CPR, give epinephri... |
[
"How is Tysabri ( Natalizumab ) produced? \"Natalizumab is a humanized monoclonal antibody\"... do they just have a farm of laboratory mice growing somewhere?"
] | [
false
] | Relevant wiki Laymen's explanation of its use and method of action: For MS patients, its the most extreme treatment option. It won't stop the progression of MS but does slow it down and hopefully prolong or minimize the chance of developing secondary progressive MS. It acts like micro-condoms on immune cells, preventing them from passing the blood brain barrier. Downside of that last part is that the immune system is partially compromised and increases the risk of developing a PML infection in the brain or similarly developing a HSV2 brain infection. Neither are good and the survival rate has been pretty bad. To the point though, I've been taking this stuff once a month for two years. It does work and has been phenomenal. Still, I'd like to know how it's made, or at least made in sufficient quantities to treat myself and the few other thousand(s) of patients receiving it. | [
"The ",
"European Medicines Agency",
" has what looks like a ",
"helpful document",
" on Natalizumab, where they mention the following:",
"Natalizumab is a purified, recombinant, humanized ",
"monoclonal antibody",
" against the integrin Ξ±4-subunit (IgG4/ΞΊ). Natalizumab is produced in non-immunoglobul... | [
"Monoclonal antibodies are generally made by cells in culture -- specifically, by B cells (the cells that produce antibodies) fused with cultured tumor cells to make hybrid cells called hybridomas.",
"When you want to make an antibody to a particular protein (in this case, alpha-4 integrin), you expose a lab anim... | [
"... Hence why these molecules are so expensive "
] |
[
"Space's rate of expansion increases with distance. So is it theoretically be possible to go so far that light would never reach you?"
] | [
false
] | Came up when discussing physics over beer. | [
"Metric expansion works like compound interest. At a given rate of interest accumulation, how much you earn is a function both of how much time you let your money sit there ",
" how much money you started with.",
"Metric expansion can be quantified, at any given instant of time, in units of length per unit of t... | [
"Yes, this is true. There are parts of the universe we can't see even today.",
"In fact, space is expanding so fast that in billions and billions of years, we won't be able to see anything outside of our own galaxy (which will by then have merged with others). Civilisations that rise up in this period will never ... | [
"And, you know what? For all practical purposes, they'll be right.",
"And asking ",
" would be meaningless."
] |
[
"You need energy to light a fire, but it also gives out thermal energy - so is it a endothermic or exothermic reaction?"
] | [
false
] | As I see it, it's: A carbon-hydrogen-oxygen molecule + O2 --> CO2 + H20 But I'm confused about the definition of endo/exothermic reactions, and how that relates to burning. Followup question: Is it possible to burn water? | [
"I'm pretty sure any normal definition of combustion requires it to release heat, so endothermic reactions wouldn't be combustion by definition.",
"That said, endothermic reactions can occur during combustion; for example, oxidation of nitrogen (e.g. N",
" + 2O",
" --> 2NO",
") is slightly endothermic, and ... | [
"Combustion is almost always exothermic, it releases a lot of energy as it goes. However most reactions do not just happen when you get two things close to each other, you need to provide them with enough energy to start the reaction. It is often necessary to get the molecules very close together which requires g... | [
"Combustion is almost always exothermic",
"Do you know of any situations where combustion is ",
"thermic?"
] |
[
"How close is the Earth right now in its orbit as it was exactly one year ago? (In relation to the Sun)"
] | [
false
] | null | [
"(Assuming that by \"year,\" you mean at midnight on 12/31 last year).",
"Well, the period that it takes Earth to orbit the sun is about 365.2564 days; since this was a leap year, this is a difference of about .7436 days. So we've gone .7436/365.2564 = .002036 extra orbits around the sun.",
"Now the distance to... | [
"The others here are missing a critical point, that of ",
"apsidal precession",
" and ",
"variation of its eccentricity",
". The Earth's orbit is never exactly the same year to year."
] | [
"Nope. See silpion's comment for some minor effects that make the orbit different every year."
] |
[
"If you did not consider the sun, is the mass:area in our solar system higher, lower, or similar to that of the stars in our galaxy?"
] | [
false
] | That is, if you considered the ratio of the mass of all planets/asteroids etc. vs the space they orbit in and compared it to the mass of all the stars vs the space they orbit, which would be higher? | [
"System mass 1.0014 solar masses",
"solar mass 1.98855 X 10",
"Mass of Solar System",
"(1.98855 X 10",
" * 1.0014 = 1.991334 X 10",
" kg",
"Mass of solar system without sun",
"1.991334 X 10",
" - 1.98855 X 10",
" = 2.784 X 10",
" kg",
"Solar System 1 ly across (trying to include Ort ... | [
"Perhaps I missed it, but don't you need to account for the area not diamater of the milky way? I mean wouldn't it be lyrs",
" *pi? And isn't the milky way significantly more than 120 light years? (I thought tens or hundreds of thousands)"
] | [
"Oops yes my bad I missed a K in the numbers I pulled lol\nit was 120K ly haha This is what I get got pulling numbers fast while i at work and not focusing. :D I litterly had to hide what I was doing.",
"I just went for the diameter as if it was on 2d plane as since the shape of the galaxy is more complex then ju... |
[
"Is it more fuel-conscious to accelerate quickly in a car or to slowly work up to a certain speed?"
] | [
false
] | null | [
"Read this:\n",
"http://www.reddit.com/r/askscience/comments/igmfe/why_is_rather_quick_acceleration_and_high_gear/"
] | [
"The conclusion is correct, but the explanation isn't very good.",
"High gears are better because \n* frictional power losses scale as the cube of rpm\n* more time is available for scavenging at lower rpm",
"In addition, spark ignition otto cycle engines typically modulate power by using a throttle valve. This ... | [
"I think this was asked last week. It's in the subreddit somewhere. "
] |
[
"Why are fluids practically not compressible?"
] | [
false
] | Which forces make it practically not possible to compress a fluid significantly? Why is it not possible to compress the molecules further together? Fluids have nearly zero shear resistance, when you apply the force slowly. So why is it not possible to change the distance between molecules in a fluid? | [
"Molecules in a ",
" (as opposed to gasses, which are also fluids) are effectively \"touching\" one another, in the sense that they're close enough for electrostatic forces to be significant. Push the molecules closer and those forces ramp up very fast.",
"Contrast that with a gas where the molecules are so fa... | [
"As an Mechanical Engineer we should take the blame for this. We use incompressible in a different way. We use it to descrbie what happens when you stretch a material. The volume of many materials change as you compress them from one side. This is called the Poisson ratio. At one extreme is cork. If you compress it... | [
"Cohesive and Adhesive forces. If liquids were perfectly solid, then of course the cohesive forces would be so powerful to not allow any type of adhesive force to exist. For this to occur the universe would have to cease its existence unless adhesive forces were preserved within the atom or molecule itself as the ... |
[
"If instincts are genetic, is it possible to find and alter the genes responsible to make any information instinctual? (In theory)"
] | [
false
] | [deleted] | [
"What do you mean by 'information'?",
"You could almost certainly affect behavior by changing genes involved in instinctual responses, but there would be boundaries on what exactly you could do. It becomes difficult to ascertain exactly what those boundaries would be since we know so little about what genes are ... | [
"I think the face recognition ability of infants is something that must involve coding some form of abstract face recognition into the brains that is genetic. Babies are born with rough model of what face is (eyes, nose, mouth) and they develop more specific model over time. ",
"http://onlinelibrary.wiley.com/d... | [
"Now, it would be ludicrous to think you could \"instinctually\" insert learned human knowledge - like knowing state capitals or how to do calculus - but rudimentary behavior might be possible.",
"Well, in ",
" nothing would make it impossible, physically. In practice it would be so mindboggingly complex to eng... |
[
"Examples of application of automata in software engineering"
] | [
false
] | As a CS major (in Canada) we learn far more theory than application. We learned about FSA, DFSA, CFG and so on, yet we never learned how to apply them or examples of how it's applied. Please expand upon this, thanks! | [
"To give another NLP example, some (most?) part-of-speech (i.e. noun, verb, adjective) taggers use hidden markov models, which are pretty related to finite state automata: the system traverses from state i to state j with probability p-ij, and samples some probability distribution associated with state j. To 'tag' ... | [
"To give another NLP example, some (most?) part-of-speech (i.e. noun, verb, adjective) taggers use hidden markov models, which are pretty related to finite state automata: the system traverses from state i to state j with probability p-ij, and samples some probability distribution associated with state j. To 'tag' ... | [
"Please correct me, if I'm wrong, since I understood, you are requesting very specific/concrete applications for automata.",
"A potential application is the string-matching problem. Using an automaton you can solve it pretty efficiently. If you are interested, the algorith of Knuth, Morris and Pratt may be releva... |
[
"Is a low calorie cooking oil possible?"
] | [
false
] | [deleted] | [
"Yes, it's possible to make oils that have no calories (",
"olestra",
" is one example). unfortunately, they have unpleasant side effects, like anal seepage."
] | [
"That's just a marketing gimmick. For cooking spray there are about 7 calories per second of spraying, and it's only low because it's such a small amount of oil."
] | [
"And this would be why I am not a scientist."
] |
[
"When I run for an extended period of time I get a stitch in my side, what causes this?"
] | [
false
] | By stitch I mean a sharp pain in my abdomen. Usually if I keep running it goes away, but often it comes back. What can I do to prevent it? Why does it happen? | [
"it happens because of the way the liver and diaphragm are attached. when you are breathing rhythmically with your pace, remember the liver is pulling down on the diaphragm with each right sided footstep, due to gravity. when the diaphragm is pulling down because you're breathing in, and the liver is pulling down... | [
"Is there any way to prevent the pain? Habits, nutrition, etc?"
] | [
"In my case it diminished with time and training. (Sorry if this violates the no anecdote rule it is solely my own observation and experience)"
] |
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