title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How can the universe be created ex nihilo?"
] | [
false
] | I originally posted this in and was directed to come here. I know Stephen Hawking has been talking quite a lot about this lately -- how the laws of physics reveal that the universe had the ability to create itself from nothing...but how? How is this possible? Can anybody explain? It just doesn't make any philosophical... | [
"You have to first define what exactly is \"nothing\". Because in modern physics, if you have \"nothing\", literally create a vacuum where there are no particles whatsoever, quantum fluctuations will still create a measurable energy.",
"Laurance Krauss wrote an excellent book on this very subject, conveniently ti... | [
"You have to first define what exactly is \"nothing\". Because in modern physics, if you have \"nothing\", literally create a vacuum where there are no particles whatsoever, quantum fluctuations will still create a measurable energy.",
"If you want to get philosophical and redefine \"nothing\" as something with n... | [
"You have to be very careful with asserting that something \"doesn't make scientific sense\", because some parts of science have very very little to do with common sense and are still making valuable predictions (see quantum mechanics).",
"Truth is, nobody today has an unique theory to explain the beginning of th... |
[
"Is it possible mental disorders were present during biblical times? Or are they something that have grown more in recent years."
] | [
false
] | [deleted] | [
"Virtually all known mental disorders are not caused by anything specific to modern times (e.g., technology, ozone depletion, etc). However, there is extensive data to suggest that some disorders are exacerbated by modern factors (e.g., pollution, pesticides, toxin contamination) and increased in prevalence due to ... | [
"However, there is extensive data to suggest that some disorders are exacerbated by modern factors (e.g., pollution, pesticides, toxin contamination)",
"Can we have a citation to go with those factors?"
] | [
"Not only is it possible but I cannot imagine anyone would try to argue otherwise.",
"It isn't a possibility but a fact.",
"Link to a relevant wikipedia article"
] |
[
"What is the gas inside a pepper and other vegetables?"
] | [
false
] | I always wondered this. Do hollow vegetables like peppers or the leaves of green onions contain specific gas inside, and why? Is it ethylene, or did the plant just envelop air as it was developing? | [
"One time solanaceaous plant geneticist here (tomatoes, peppers, potatoes).",
"It's pretty much a mixture of oxygen, carbon dioxide, nitrogen and some water vapour and trace amounts of volatile plant metabolites.",
"The specific ratio of the gases is pretty different to the normal atmosphere, there's a lot more... | [
"does the gas composition have any function, or is it just incidental to the fruit's metabolism as it develops?"
] | [
"I don't actually know and hadn't previously though about that. A quick google didn't come up with anything. I would assume it's the latter as oxygen and carbon dioxide are photosynthesis/respiration by-products so I'd guess that the different levels reflect different amounts of metabolism at different fruit growth... |
[
"What is the physical difference between a laser in a laser pointer and a laser that can etch things?"
] | [
false
] | Follow up question, are the lasers that can cut straight through people, like in the Resident Evil movies, realistic? | [
"So there are many different ways of building a laser (which is an acronym standing for Light Amplification by Stimulated Emission of Radiation). The two that you ask about are two of the most commonly used, first being the semiconductor laser (laser pointers, dvd players) which are cheap to make, relatively low po... | [
"Is this the youtube video you were referring to?",
"www.youtube.com/watch?v=awsQs4ct0c4",
"More info:",
"http://www.onr.navy.mil/Media-Center/Press-Releases/2011/Maritime-Laser-MLD-Test.aspx"
] | [
"yeah thats exactly it. An oldie, but a goodie! gives a pretty good demonstration of how lasers aren't quite what are portrayed in James Bond movies, but still impressive, and I'm sure this isn't as powerful as the current research lasers both at Northrop (claimed ~100kW power) or the highest ever output at Lawrenc... |
[
"Why doesn't the stomach digest itself?"
] | [
false
] | null | [
"Stomach mucosal barrier prevents stomach acid from breaking the stomach lining down. NSAIDs and certain bacteria such as H. Pylori neutralize the barrier which ends up damaging the stomach from acid and causing perforations to ulcers."
] | [
"Thanks"
] | [
"Fun fact. H. Pylori is a bacteria associated with most stomach ulcers (at least in the US). Chronic cases can lead to MALT-Lymphoma, a form of cancer. This turns out to be one of the few instances where antibiotics can treat and cure a cancer via treating the H. pylori infection itself. Many (but not all) of the M... |
[
"Gal4/UAS Systems?"
] | [
false
] | I would really like someone who has a thorough understanding of this research tool to explain it to me. I've tried reading a few reviews about it and they don't make a lot of sense to me. They all start with "Gal4 lines", but I want the explanation to go further back than that. How is a Gal4 line created? How is it cre... | [
"I believe most Gal4 lines in flies are made with transposable elements (",
"all things in this list that are P{stuff here} are transposons",
"). They can be mobilized in the animals and will randomly insert themselves in the genome (",
"1",
", ",
"2",
").",
"Once they're inserted, the genes in the tr... | [
"Is the expression pattern of the Gal 4 gene based on where in the genome it was inserted? If so, and the insertion is random due to the nature of the transposase, then was every fly line that has Gal4 specific expression in varying tissues at varying times created randomly and then verified by crossing with a UAS-... | [
"Yes, the expression of the Gal4 is based on where it was inserted (",
"called an enhancer trap",
").",
"That's that way it used to be. However, now people put in specific chunks of DNA to control the Gal4 ",
"(example)",
" because we know much more now about what promoters drive expression when and where... |
[
"Why does white light only split into the visible spectrum?"
] | [
false
] | null | [
"It splits the light in more colors. This is famously how infrared light was discovered."
] | [
"How many more colours? \nI'll check out the discovery of infrared, it sounds interesting"
] | [
"Outside the visible spectrum we don't really have defined colors. The main limitation is that the prism material is not transparent to all wavelengths."
] |
[
"My dentist wants to keep the tooth I just had extracted for research -- what will they do with it?"
] | [
false
] | Just curious as to why they would want to keep my tooth and what it would typically be used for? | [
"Check under his coat for wings, there is a good chance he is the tooth fairy."
] | [
"Dental pulp stem cells",
"?"
] | [
"That is the cutest comment I've ever heard. "
] |
[
"Why do all modern windmills have three arms, and why are they all white?"
] | [
false
] | Sorry if arms isn't the proper term, but you get the idea. | [
"The arm on a windmill actually bears significant aerodynamic similarities to a wing. It turns out that in the usual windpeed ranges of operation, it is more efficient for aerofoils to have a high aspect ratio (long skinny form). ",
"Another similarity that windmill aerofoils have to wings is that they leave a wa... | [
"The more blades on the turbine, the more energy it will extract, but this diminishes quickly. Cost generally goes down with less blades so somewhere there is a balanced choice. It's really only a choice between two or three, and for big turbines, a two blade setup has bigger oscillations, and needs to be built in ... | [
"Its advantageous to have an odd number of blades. This reduces the vibration caused by the difference in wind forcing between the blades at the top of their arc and the blades at the bottom. ",
"If you're stuck with odd numbers the first possible grouping is 3, then 5, then 7. So why 3? Wind turbines work best a... |
[
"Do you have to subtract 68 years from carbon dated values because of nuclear testing after 1950?"
] | [
false
] | Read it somewhere but I feel like either it was wrong or I'm misremembering. | [
"We do have to account for varying levels of carbon-14, but it's not just subtracting a number of years. We measure the amount of carbon-14 in the atmosphere over time, which doubled during atmospheric nuclear testing in the 50's and 60's. Since we know how much carbon-14 is the atmosphere and it decays at a predic... | [
"I did some more reading on it, and apparently you can use radioisotopes in bones to calculate someone's age (if they were born after 1950ish). Basically certain concentrations correspond to certain atomic blasts, so if you know the amount you can work out which bomb went off in the same year as the person."
] | [
"Thanks. I suppose you could use tree rings or something like that to work out what the level is for every year."
] |
[
"After the recent eruption in Hawaii, it is clear to see how it affects life on land. My question now is how does it affect life in the ocean? Does the water in contact with the lava super heat it, killing off any organisms living close by?"
] | [
false
] | null | [
"First, there's no \"after\" about it. The hype has slowed down but the volcano has not. Here is the ",
"official status",
".",
"Here's a ",
"recent news update",
" about the lava flow that is currently entering the ocean. Specifically, look at the following quote from the June 8, 6am update:",
"Strong ... | [
"So you’re telling me booking a last minute trip to Hawaii will be cheaper right now?"
] | [
"So maybe a bit off topic but I probably wont find any other Hawaiian residents anytime soon but just how bad is the vog on the kona side? I'm looking at planning a trip there many months down the road when it most likely will have subsided and want to take advantage of the much cheaper airfare right now. What's th... |
[
"If you have access to complete knowledge of the state of a system, but only at one instant of time, is it possible to determine the velocities of the particles in that system at that instant?"
] | [
false
] | When I say "complete knowledge" I mean knowledge of any physical property of the system at that instant, and no knowledge of future or past states of the system. Basically like having access only to a single 3d slice of spacetime, where t is held constant. Basically, is something like velocity "encoded" somehow within ... | [
"Pedantic response:",
"The question is non-sensical because you haven't defined what \"complete knowledge of the state of a system\" actually is. \"Systems\" and \"states\" are just pragmatic mathematical tools for describing things, and the concrete things those represent differ depending on context and who is d... | [
"Oh boy this is a good one.",
"Let's start out with classical physics, no quantum. Imagine the entire universe consists of exactly two massive particles confined to one dimension. The physical law governing this situation is Newton's law:",
"F = m a",
"Since the two particles are massive (and let's say charge... | [
"So in your quantum example, you are assuming that all probability wave functions have collapsed to knowable positions and momentums for all particles? If not, there would be no way of predicting what the system would look like at t+1 beyond certain probabilities for how each particle might move due to its momentum... |
[
"Question about probability.."
] | [
false
] | If I have 600 chances to do a certain action for a random number of seconds, between 1 and 60, what is the average number that will result? How is this figured out, mathematically? Thanks, it's been a very long time since learning this, and I feel dumb. | [
"I'm not sure if I understand your question, but a single action will take on average (expected value) (1+2+...+60)/60 = 30.5, assuming uniform discrete distribution. If you do it 600 times, the average will still be 30.5, by additivity of expected value. Maybe you wanted something different?"
] | [
"I am really confused by your question. Would you mind trying to explain to me what you mean in other words ?"
] | [
"No, I guess that's it. I just made it way more complex in my head. I'm trying to figure out how many seconds is wasted at my work when an employee takes a certain action. ",
"See at my job, when an employee goes 'afk' this is tracked and they no longer receive calls. I'm trying to find out on average how many ca... |
[
"Is it true that one pound of body fat is equivalent to 3,500 calories?"
] | [
false
] | null | [
"Which is why there's a capital C there."
] | [
"Which is why there's a capital C there."
] | [
"Calorie with a capital C is an internationally-recognized way to denote kilocalories, and we're in a thread about dietary kilocalories. I'm not sure it could be any more correct or unambiguous than that."
] |
[
"How are seesaws not considered the solution to perpetual motion? And what about those little toys that look like birds drinking water?"
] | [
false
] | null | [
"You have to keep pushing off the ground to keep them in motion."
] | [
"But even then isn’t the motion created still perpetual?"
] | [
"No, it requires chemical energy from the legs and loses kinetic energy to the air."
] |
[
"If a male St. Bernard breeds with a femal Chihuahua, would the fetus grow so large that it would kill its mother?"
] | [
false
] | [deleted] | [
"Artificial insemination. "
] | [
"While you may very well be right, please don't speculate. "
] | [
"You know, I think this is an experiment that the askscience community can work together to resolve. "
] |
[
"What genetic diseases/syndromes are more prevelant in Europeans than other ethnic groups?"
] | [
false
] | For example, it is often stated that sickle cell anaemia and diabetes affect people of Afro Carribean descent more, as lactose intolerance is also more prevelant in south eastern Asians. What intolerances/genetic diseases are found more in white Europeans? | [
"Lactose intolerance is not a genetic disorder. It's the standard. Lactose tolerance, which is prevalent in europeans, is the more recent genetic adaptation. It's actually one of the clearest examples of recent natural selection in human populations. Lactase persistence clearly conferred a selective advantage i... | [
"My understanding is crohn's is more common on those of european heritage (will find a source, but I am a crohn's sufferer)"
] | [
"Actually the process of making cheese substantially decreases the amount of lactose in cheese. So most lactose intolerant people should be fine consuming most cheeses.",
"http://www.ilovecheese.com/lactose_intolerant_faqs.asp"
] |
[
"How did we first measure the speed of light?"
] | [
false
] | null | [
"(Good old Olaf](",
"http://curious.astro.cornell.edu/question.php?number=269",
")",
"Also from Wiki:",
"Ole Rømer first demonstrated in 1676 that light travelled at a finite speed (as opposed to instantaneously) by studying the apparent motion of Jupiter's moon Io. In 1865, James Clerk Maxwell proposed tha... | [
"Adam Savage explains it ",
"here",
" . Pretty interesting. "
] | [
"Early measures were indirect and relied on astronomy. Rough estimates could be made based on the timing of Jupiter's moons when the earth was nearer or further away. The speed of light can also be inferred from the stellar aberration, which causes the apparent position of stars to change slightly due to the eart... |
[
"Why don't humans show coat patterns like Calico cats do due to X -Chromosome inactivation?"
] | [
false
] | Had watched a few videos and read a little when I came across how female Calico cats have differing coat colours depending on which X chromosome gets inactivated. Why doesn't this happen with human skin? Also, in what situations do calico males have the patterns that females do? | [
"Human genes that control skin and hair color aren't located on the x chromosome like they are in cats. An example of this in humans though is a gene that controls sweat pores. This gene is on the x chromosome and many women have sporadically placed sweat pores."
] | [
"Sweat glands and cat stripes tend to follow ",
"Blashko's lines",
", a pattern left behind by folds during embryo development. One cell goes one way and so do all of its daughter cells, and they are folded again and again like mixing two kinds of paint.",
"It's rare but humans can have a mutation effecting c... | [
"Wow this is cool. And didnt Turing workout the mathematics behind a lot of these patterns that can form? Also, what is the name of the striped human disorder? Id like to see if i could find a picture"
] |
[
"Are there any consumable liquids that don't contain water?"
] | [
false
] | I know various acids (HCl, etc) and other liquids don't contain water but are there any that humans can drink? | [
"Just so nobody gets a rude surprise, mineral oil is a laxative."
] | [
"Yes, but not in large quantities. You can drink pure alcoholic drinks that contain only trace amounts of water and are almost pure ethanol. You can also drink various oils that are used for cooking."
] | [
"It should be noted that all acids have water in them. HCl has to be aqueous to be an acid. Otherwise it is a salt. (I think)",
"Mineral oil is perfectly fine with the human digestive tract. Also, there are other oils, such as vegetable oil, canola oil,and olive oil, that are okay with people."
] |
[
"Why do we assume for life to exist on other planets it would need to have “Earth like attributes” when it took us billions of years for life to begin/evolve?"
] | [
false
] | null | [
"Because whe know only a planet which has live on it and it it the earth. So if life it’s possible here we look for planets with same conditions because it’s more likely to host life. Howevere there still could be life in non earth likely planets. It would be simply harder to explain it. 😁"
] | [
"For a few reasons:\n1- The only known life with which we have working experiences is derived here on Earth. We have no other template to go off of.",
"2-Life is a biologically complex set of processes that we are still developing an understanding of (relative to life on Earth specifically). To be able to diagram... | [
"It's actually probable that life began significantly less than a billion years after the formation of the planet. The earliest conclusive evidence of life is ~3.5 billion years old but there are microfossils and geological formations that may be indicative of living things that could be as old as ~4.3 billion yea... |
[
"Do hot air balloons work better in cold weather?"
] | [
false
] | null | [
"The buoyancy achieved by a hot air balloon is related to the difference in density between the hot air (less dense) inside the balloon and the colder air (more dense) outside the balloon. ",
"If the air gets colder outside the balloon, and the air inside stays at a constant temperature, then the balloon would be... | [
"The reason for morning/evening flights is to avoid thermals that can make for unpredictable rides.",
"http://www.hotairballoon.org/vermont/faq.html"
] | [
"This made me curious if the balloon section (Envelope) was insulated, it doesn't seem it is. ",
"Looking at a fabric manufacturers literature makes it seem like the most effective way to increase flight time is reduce porosity of the material. (1)",
"It seems fuel consumption would increase in cold weather, bu... |
[
"What causes the \"auras\" or \"halos\" when staring at a speaking person?"
] | [
false
] | Sitting in a passive physical state, watching a speaker and as you "zone out" on that speaker, you start to "see" a fringe of light around the speaker. Some common examples: watching a speech at a conference, at a large company meeting with a presenter, or a church service. Dim lighting helps, but is not required. In... | [
"I believe what you're describing is called ",
"Troxler's faiding",
"."
] | [
"I can see the effect in this example gif but I've never experienced this \"aura\" illusion. That doesn't sound like the same thing, in fact they sound like completely opposite effects: this fading illusion is your nervous system ignoring visual information that IS there while what you describe would have to be you... | [
"That's probably it. If you spend 10 seconds looking at the chest of a person in a black suit in front of a white wall from a distance, then move your eyes to his head, you will see the afterimage from the body around his head."
] |
[
"waves and conservation of energy"
] | [
false
] | I took an oceanography class last quarter and they taught us two facts that together seem to violate the conservation of energy. First, they taught us that when two waves with height x constructively interfere, the resulting wave has a height 2x. Second, they taught us that a wave's energy is exponentially proportional... | [
"Second, they taught us that a wave's energy is exponentially proportional to its height, so a wave of height 2x would have 4 times as much energy as a wave of height x.",
"Just to clarify, I think that you mean that it is quadratically proportional, in other words the energy is proportional to the height squared... | [
"Your explanation is good for explaining why more energy is needed to make a higher wave, but I want to make it clear that he specifically asked about the case of interference, and not the case of making a new wave.",
"\"So a wave of height x and wave of height x ",
"...\"",
"And no, it does not take 4x the e... | [
"Imagine a long pool with albert at one end and beth at the other.",
"The pool is still.",
"At the moment a bell rings, both albert and beth start waving their paddles.",
"Both are waving in still water, both are generating a wave with the same amplitude, both are putting in the same energy.",
"Let's say th... |
[
"Two planets sharing one moon?"
] | [
false
] | EDIT: ELI5 as much as you can please! I have a general knowledge of how things work out there, but that’s about as far as it goes. I have a sci fi literary idea that I would like a realistic scientific framework for. I am hoping to find some help here for these questions: Would it be theoretically possible for two plan... | [
"While you can find a ",
"mathematical solution",
" for such an orbit, it requires such precise positioning and starting momentum for every object in the system that even a tiny pertubation will shove it into an orbit of one of the two planets. I wouldn't expect to find any natural objects in such an orbit, and... | [
"This would be possible but terribly difficult. The moon would have to follow an orbital path that precisely passes over the Lagrange point L1 of the binary planet system. This particular orbit is metastable. This means that any deviation in the orbit will cause the moon to break off into a lower energy, stable orb... | [
"It’s ",
" impossible for two planets to even share the same orbital path and remain stable, and if they were close enough to share a moon they would have coalesced into a single body during formation. In a ",
" rare circumstance where one planet was formed and then sometime later another planet was captured mo... |
[
"How to tell if a semiconductor is n-type, p-type or pure through testing?"
] | [
false
] | [deleted] | [
"Look at the sign of the ",
"Hall conductivity",
". For the experimental setup, it's easiest to look at the picture in the \"theory\" section of that wiki page. The voltage that you measure will have opposite sign for n versus p type doping. "
] | [
"Another super easy test is the thermoelectric voltage described in ",
"this PDF from Keithley",
". Basically you heat up a portion of a material, then look at the polarity of thermally generated carriers diffusing away from the heated area. That PDF also describes another 4-pt probe method.",
"Also, if you w... | [
"This might be more complicated, yet practical, but grab a known semiconductor material and clamp them together and apply a battery across it in various configurations with a series ammeter. If they match, they won't conduct very well, but if they are the opposite dopant, they will exhibit the typical PN diode effe... |
[
"What the heck does Kd really mean?"
] | [
false
] | I'm a biomedical student having to repeat a molecular interactions course. This whole thing just really trips me up. I understand it's a measure of affinity. I understand it's a ratio of rate constants. But I don't it. What the heck does it mean? | [
"The best way to think of it is the concentration of the ligand at which half of the proteins have bound the ligand. Why this is what it means comes down to working through the equations.",
"If you think of it this way, then it becomes intuitive that a low Kd means a high affinity interaction, because it takes le... | [
"d is not a rate constant, it is the dissociation constant. The dissociation rate is ",
"-1, which describes NR to N+R in your N+R<—>NR diagram and has units of s-1 (per second). ",
"d has units of concentration.",
"What ",
"d gives you is a description of what concentration of ligand (N) is required to mak... | [
"The units for rate constants do in fact have units in concentration, and the power of the concentration units depend on the reaction equations.",
"See ",
"http://en.wikipedia.org/wiki/Rate_constant",
".",
"Have you gone through Michaelis-Menten kinetics yet? That's when I decided in biochemistry it was bes... |
[
"Why does the night sky seem clearer during cold weather than warm weather?"
] | [
false
] | I live in an area with frigid winters and hot summers---it has always seemed, for as long as I can remember, that more stars are visible during the winter. I'm not sure if it's because it gets darker earlier (thus I see a darker sky earlier in the evening and remember it as a fixture of winter), or if there is some oth... | [
"This is NOT my specialty by a longshot, but I am an amateur astronomer...",
"There are two main reasons that I know of.",
"(1) Cold air holds less moisture than warm air. Water vapor causes refraction of light, so dry air is clearer than humid. Since the maximum amount of water vapor that can be held by cold a... | [
"Humid air is less dense than dry air. Light does not refract in a uniform substance, so I doubt your claim that water vapor causes refraction of light. Water vapor does, however, encourage the formation of haze in the presence of heat and light, so sunny, warm, humid days will have more haze that can carry over in... | [
"Doesn't cloud cover provide some insulating effect to the area underneath, making this a case of the observed effect actually being the cause to some degree?"
] |
[
"Late Night thoughts on Big Bang"
] | [
false
] | So maybe this belongs more in ... but I was thinking and came up with a (completely baseless) new theory on how an event like the Big Bang could have happened. What if a large object with 4 or more spatial dimensions came in contact with a pre-existing "universe." What if it moved part of the 3D object into the 4th Di... | [
"[8]"
] | [
"Or at the very least \"Here's the Lagrangian, I'll be in the john.\""
] | [
"Here's the thing:",
"It's very easy to do mental constructions on \"what would happen if dimension X brane and large object did Y\", but it's not physics until you say: this theory predicts ",
" for this quantity, or at least make some qualitative prediction or give insights for some self-consistency issue. ",... |
[
"Is there evidence of any animal evolved from land to water and then back again?"
] | [
false
] | As in a wolf to a whale and then back to a land animal again? | [
"Whales had ancestors that were terrestrial and if you go far back enough those terrestrial ancestors themselves had aquatic ancestors. The time gap between the two events is huge but, I hope it still fits what you are looking for. ",
"Evolution of Whales"
] | [
"Not so much evidence, but there is a hypothesis that ",
"we did",
".",
"The hypothesis explains some aspect of human physiology but there is no empirical evidence to support it. From what I understand, it is generally regarded as unlikely to be correct."
] | [
"Land turtles (tortoises) are likely an example of this. Aquatic turtles are like whales, descended from land dwelling ancestors. You might think that Land turtles are cousins to aquatic turtles that branched off before they returned to the water, but that seems unlikely. The branches of the evolutionary tree that ... |
[
"When someone gets shot why is it so critical to remove the bullet?"
] | [
false
] | null | [
"Penetrating trauma is dangerous because it can damage multiple deep structures without the damage being immediately obvious. I think probably the most useful thing to do surgically is to explore the wound to see how much damage has been done and repair it if necessary. Once you find the bullet that's a good indica... | [
"Doctor here,",
"Not all bullets ",
" to be removed. In the case of abdominal wound, an exploratory laporotomy is usually indicated for the assessment of any organ damage and typically the bullet is found and removed at that point. However, if fragments were to be in benign locations(like in soft tissue) and re... | [
"You are correct, dunno how much of a problem metal poisoning is since it is common practice to leave bullets in the body and people live their lives perfectly fine.",
"QUICK EDIT: i think it may be a problem if those are lead bullets though."
] |
[
"How does the gravity work on earth?"
] | [
false
] | The sun curves the space and that makes the earth orbit. And its the same with earth and the moon.. But how does the gravity work here on the earth? Does is curve here aswell? Or is it the graviton which keep us down, and how does it work? | [
"Here's a very direct way to see how curved spacetime is here on Earth.",
"Take a ball. Choose a target a couple of metres away. Now throw the ball so that it reaches the target in one second.",
"What the ball is doing is taking ",
" from one point to another point, separated in space and time by 2m and 1s.",... | [
"It's not because we're closer, but because of our speed. If we were moving at orbital velocity just above the surface of a planet (assuming no air resistance or mountains to crash into) we would stay in orbit. If the Moon were to stop relative to the Earth, it would fall straight down."
] | [
"I think by \"spinning\" you mean orbiting. The best way to think of this is take a marble in a funnel. The faster the you spin the marble [around the funnel not around it's own center] the closer you can get to the bottom without falling in. whereas the higher up in the funnel you place it the less speed you ne... |
[
"Since coal is formed from plant matter, doesn't burning coal just release carbon that was previously in the atmosphere?"
] | [
false
] | My understanding is that coal comes from peat (decayed plants.) When we burn coal, are we not simply returning carbon to the atmosphere that existed in the atmosphere during that plant's lifetime? | [
"Yes, you are correct.",
"Be careful if this leads you to conclude that carbon dioxide isn't dangerous. For instance, a lot of carbon was buried and became coal during the carboniferous. ",
"This large scale burial of carbon was very possibly linked to a massive ice age, with massive sea level drop, and a mass... | [
"1) We are releasing the carbon back into the atmosphere far faster than it was trapped in the Earth to begin with.",
"2) When we burn coal, we are not simply releasing CO2. Coal burns imperfectly, and contains other substances like sulfur; both of these factors contribute to the release of toxic compounds when b... | [
"The Earth's ecosystem trapped (and still traps) carbon at a certain rate, when the rate released exceeds the rate trapped, you get extra CO2 (and other compounds in coal) and all that extra stuff floating in the air isn't what the Earth's ecosystem is used to having in its air."
] |
[
"Is arcing a more efficient way to transfer electricity versus a conductive wire? Ignoring the obvious safety concerns, could we have arc towers instead of power lines?"
] | [
false
] | null | [
"I suppose my implied question was 'is air more resistant than wires?'",
"If air wasn't more resistant than wires, the electricity wouldn't stay in the powerline wires. They'd arc right across."
] | [
"No. Electricity follows the path of least resistance and given the first opportunity would arc to ground or the nearest metal structure. The resistance of the atmosphere is too great and unless the \"arc towers\" were very close together it wouldn't work. Besides hideous safety concerns, concerns for wildlife, and... | [
"Thing is, Plasma is hot, so the efficiency of passing electrical current through it is dampened by the fact that it naturally dissipates energy as heat, besides the fact that the plasma is also less dense than the surrounding air, resulting in ",
"anything ",
" a linear path",
", as the arc naturally travels... |
[
"Why are stimulants bad for your circulatory system, but aerobic exercise is good for it?"
] | [
false
] | null | [
"Long term, coffee drinking is probably good for you.",
" The real problem with abusing stimulants is that it's so easy for one to put their circulatory system under more strain than it has been conditioned to handle. ",
"Similar strain can be induced through exercise",
", but most people will simply give up ... | [
"So, theoretically, could you take small amounts of stimulants to simulate aerobic activity?"
] | [
"There's much more to exercise than an increase in heart rate. i.e. lung capacity, oxygen efficiency, ect.. Regardless, I can't imagine any professional advocating taking any amount of stimulants(that aren't caffeine). Let alone to stimulate aerobic activity."
] |
[
"Are there lone groups of \"planets\" in the distance between stars?"
] | [
false
] | null | [
"Groups? Doubtful. Rouge planets do get kicked out of solar systems during their formation, or systems with complicated and unstable orbits can eventually kick out a planet (or gravitational interaction with a nearby stellar mass object). There's an article on ",
"r/science",
" where they measured Saturn's grav... | [
"In addition to ejected planets, there's also the question of whether we should consider lone ",
"sub-brown dwarfs",
" to be rogue planets, a subclass of brown dwarfs, or just their own category (like how true brown dwarfs are usually considered neither stars nor planets). From what I can gather from reading t... | [
"There may be more rogue planets between the stars than there are stars in our galaxy. ",
"http://blogs.discovermagazine.com/badastronomy/2011/05/18/the-galaxy-may-swarm-with-billions-of-wandering-planets/#.VHDBNsktzOM",
"It seems likely some of them could be in orbits with each other."
] |
[
"Thermodynamics of supercharged car, powered by compressed petroleum gas."
] | [
false
] | I dropped out of engineering before I had a keen grasp on thermodynamics, so I have a question for the hive. (I'll explain in layman's terms so those Redditors along for the ride can get a grip on things, along with those who have a chance of actually solving this problem!) So, firstly a supercharger compresses the int... | [
"You have to run the numbers to know for sure. No substitute for that. Too bad you dropped out before thermo; you basically are blindfolded with both arms tied behind your back on this problem because of that.",
"I'd do the research and answer the question (even as an EE, the thermo I took would be sufficient) ... | [
"If this is strictly an engineering problem, there is always ",
"r/engineering",
"."
] | [
"LPG is a mix of hydrocarbons, usually mostly propane. Butane has roughly similar properties.",
"Enthalpy of vaporization for propane: 356 kJ/kg",
"Stoichiometric mass air fuel ratio: 15.5 : 1",
"Heat removed by intercooler: 23 kJ /kg of air",
"Entropy change of air, assuming 300K air temp: ds ~ -.077 kJ/kg... |
[
"Why do we think less logically when we're afraid?"
] | [
false
] | An example; I know nobody is in my basement with the soul intent of murdering me, but every time I go down there, I'm afraid there is. | [
"Rational thought occurs in the neocortex, while self-preservation instincts such as fear are handled by the primitive brain. Your fight-or-flight response, therefore, can't directly avail itself of your best reasoning skills."
] | [
"The function of fear from an evolutionary point is danger avoidance. The relative costs of poor fear response (and thus danger avoidance) is very high in fitness terms.",
"The part of the brain most involved in fear response is the amygdala. It is responsible for linking past experience with emotional response (... | [
"When in danger time matters. You need to survive not think (overthink), there are some shortcuts in your brain that allow for fast reactions. ",
"Daniel Goleman's \"Emotional intelligence\" covers this topic very well."
] |
[
"Why do humans keep pets?"
] | [
false
] | As far as I am aware, this is a fairly universal cultural trend that people keep and care for animals. I understand the benefit of having livestock and domesticated help such as herding and hunting dogs, but why have we kept pets around that provide no immediate benefit? Do any other animals exhibit similar behavior? | [
"Generally speaking, pets cause an endorphin release lesser, but similar, to that of companionship with other people. Just as humans prefer to be in groups, (families, communities, villages, etc.) animals can cause similar feelings of safety and companionship. "
] | [
"Another factor is pets such as cats can perform a valuable service of catching pests such as mice which can carry diseases. ",
"We always made sure we had a cat when we we were raising ducks because mice loved to get into the duck shelters. "
] | [
"Actually, there are a few animals that keep other animals for utility and companionship. Some are species-wide behaviors, others regionally specific, and some are just individuals being quirky. ",
"My favorite example is a group of primates somewhere (I honestly can't remember where) that kidnap puppies from lit... |
[
"Is it possible that there was once an animal that was too successful a predator, therefore destroying its food source and becoming extinct itself?"
] | [
false
] | null | [
"Normally you get ",
"Lotka-Volterra oscillations",
" where declining prey leads to a decline in predators, which leads to a rise in prey, which leads to a rise in predators - and you get this pair of neat ecological sine waves describing the population of both.",
"Tiny, isolated and homogeneous ecosystems (l... | [
"This is quite common in apex predators. When a gap in an ecosystem, for a predator, arises either an organism evolves to fill this gap or a predator disperses to fill it. These apex predators are so fine tuned to an ecosystem they themselves become vulnerable to extinction due to their hyper-specialisation to an e... | [
"yes it is possible. It happens from the predator being very skilled and there being so much prey the predators population boosts, and with a combination of slow breeding from the prey and a high predator population."
] |
[
"Is it possible to detect a photon in vacuum without absorbing it?"
] | [
false
] | null | [
"Yes, there are some schemes for doing this.",
"Story: ",
"http://arstechnica.com/science/2013/11/counting-photons-without-destroying-them/",
"Source: ",
"http://www.sciencemag.org/content/342/6164/1349",
"In short, in this scheme there is only a ",
" that the photon will have to interact and be absorbe... | [
"No, I mean it's not possible because if we could, that'd mean we would be doing measurements at the Planck scale and we ",
" need to guess quantum gravity.",
"Of course, we're 18 orders of magnitude away (with the LHC), so...",
"EDIT: of course, if you are thinking about this as a gedankenexperiment, I'm all... | [
"Making a measurement of the gravitational field of a single photon is entirely equivalent to performing a quantum gravity measurement, so it's out of the question."
] |
[
"Is there any reason to expect mRNA-based influenza vaccines?"
] | [
false
] | null | [
"Yes, absolutely. Influenza was in fact one of the diseases used during the development of mRNA vaccines to test the concept.",
"mRNA vaccines in general have several advantages over the more established ones: they are quicker to develop and adapt, easier to produce in large quantities, and evoke a stronger immun... | [
"Only mRNA vaccines are affected from drastic numbers of allergic reactions. ",
"Citation for that?",
"The average rate of anaphylaxis in any vaccine is ",
"1.31 per million",
", while the anaphylaxis rate for the Moderna COVID vaccine is ",
"2.5 per milion",
".",
"While you can phrase that as \"the M... | [
"Only mRNA vaccines are affected from drastic numbers of allergic reactions. ",
"Citation for that?",
"The average rate of anaphylaxis in any vaccine is ",
"1.31 per million",
", while the anaphylaxis rate for the Moderna COVID vaccine is ",
"2.5 per milion",
".",
"While you can phrase that as \"the M... |
[
"If we found plant-life on another planet, would that count as finding \"life\"? Would that be as exciting for the scientific community as finding bacteria for example?"
] | [
false
] | [deleted] | [
"Life of any form would be terrifically exciting. The more complex the organism, the more striking it would be."
] | [
"I don't follow your logic. Plants are far more complex than bacteria, and therefore they would be far more exciting. Of course, as ",
"/u/fishify",
" noted, any life would be unimaginably exciting."
] | [
"Hells. Fucking. Yes."
] |
[
"On the complex number plane, why are coordinates expressed as a value, like 2i+1, and not as an ordered pair, like (1, 2i)? Or do they represent something other than corrdinates?"
] | [
false
] | null | [
"The number i can be represented by the point (0,1) on the Euclidean plane. The number 2i can, subsequently, be represented by the point (0,2) on the Euclidean plane. The number 1 can be represented by the point (1,0) as well. The number 1+2i can then be represented by the point (1,2). This is all fine.",
"In fac... | [
"We do that because we can (and it's very useful). What's really going on here is that we represent a complex number as a sum of its coordinates multiplied by the corresponding basis vectors.",
"Suppose we used usual map coordinates, we might say that some point x = 5 * ",
" + 7 * ",
" where N is a 1 meter l... | [
"Complex numbers are also points in R",
" Só each of them can be written as a pair (a,b) but as other have explained, a+bi allows usual distributive rule so is more convenient. But also, another aspect is that complex numbers are more than points in R",
" they are coordinates for which division and multiplicati... |
[
"Why can the Hubble not resolve a photo of Pluto yet can resolve a photo of a galaxy millions of light years away?"
] | [
false
] | [deleted] | [
"Galaxies are simply that much bigger than Pluto.",
"Pluto is about 6 billion km away from us (give or take a few 100 million) and has a radius of about 1200 km. That means the distance-to-radius ratio is about 5 million.",
"A galaxy has a radius of about 100,000 lightyears (this would put it in the same size r... | [
"To add to this Pluto doesn't reflect very much light and so is much less bright, reducing the image signal. ",
"Additionally, planets move relative to the Hubble telescope where as distant galaxies are effectively stationary. The famous Hubble deep field picture was taken by simply having the telescope focus on... | [
"The ",
"apparent size",
" is what matters. It is a function of real size and distance from the viewer.",
"For example Andromeda is 2 million ly away from earth, but in the night sky it would appear\nlarger than the moon if it was bright enough to see with the naked eye.",
"And the apparent size of your fis... |
[
"If time dilation increases exponentially as an object approaches a black hole's event horizon, how does anything ever reach the singularity?"
] | [
false
] | I've read that time dilation tends toward infinite as an object approaches the event horizon of a black hole. Time passes normally for the object itself, but to an outside observer they would see the object move slower and slower, until eventually it red-shifted out of the visible spectrum. However, for outside observe... | [
"Well, the key point is that time passes differently for different observers. So yes, someone looking from far away would see everything quickly redshift and essentially become frozen and dark right on the surface of the black hole (at least until it evaporates). ",
"But from the perspective of whatever is fallin... | [
"This is also the essence of the information lost/frozen hypotheses, as matter falls into a BH. The origin of the hypothesis is that as matter falls in, its information is never lost, but is left as a infinitesimal layer on the surface of the BH. Leads to the holographic principle and the holographic universe.",
... | [
"If so, how does matter actually reach the singularity?",
"It doesn't really matter. We can't observe anything that happens beyond the event horizon. There need not even be a singularity.",
"Wouldn't the majority of every black hole's mass be currently in the process of still crossing the event horizon",
"You... |
[
"A few questions about light and heat!"
] | [
false
] | [deleted] | [
"Photons can interact with matter in several different ways.",
"Photoelectric Effect",
": A photon is absorbed by an electron, and the electron becomes more energetic.",
"Compton Scattering",
": A photon is absorbed by an electron, the electron becomes more energetic, and emits a lower energy photon.",
... | [
"yes, a photon is a photon, but don't forget about basic stuff about wavelengths and the light spectrum. Blue light is higher in energy than red light. UV light is even higher in energy. These are all photons just at higher or lower energies (EDIT: maybe energies is too vague of a word... Frequencies? I believe you... | [
"Photons have different energies based on the frequency of their wave form.",
"A somewhat analogous picture is to imagine the photon vibrating as it travels. The faster the vibration, the higher the energy. This isn't actually what is happening, however.",
"Just think of all photons as having a momentum, and ... |
[
"Is it possible to catch 2 different cold viruses at the same time?"
] | [
false
] | If cold viruses are constantly mutating and always changing, doesn't that mean you can catch a common cold from one person and then catch another version of the common cold from somebody else? If I get over a cold (and so my body is well-equipped to fight that particular virus), am I safe to be around other people with... | [
"Related: It can also happen with different strains of HIV. Not only the virus itself is much worse than rhinovirus, but also the superinfection is a concern as it may lead to drug resistance.",
"http://caps.ucsf.edu/archives/factsheets/superinfection"
] | [
"Related: It can also happen with different strains of HIV. Not only the virus itself is much worse than rhinovirus, but also the superinfection is a concern as it may lead to drug resistance.",
"http://caps.ucsf.edu/archives/factsheets/superinfection"
] | [
"It's complicated.",
"If you just got over a cold, and you're exposed to, say, a family member or a co-worker who also has a cold, then there's a reasonable chance that it's the same virus you had, because the social groups you circulate in share viruses too. Even if the group is relatively distant (a school gro... |
[
"What is the general consensus about mental illness being caused by a chemical imbalance?"
] | [
false
] | [deleted] | [
"You're right about pharmaceuticals marketing chemical imbalance inappropriately. Really it stems from dualism, where people believe the mind and body are separate, which is of course ridiculous, and only in that frame does the distinction between not caused by chemical imbalance and being caused by chemical imbala... | [
"I think the notion of \"chemical imbalance\" grossly simplifies the functioning of the human brain, however I do believe that consciousness results from the neuro-chemical processes going on in the brain. Take depression for example; a sequence of bad experiences in life could reinforce chemically encoded neural n... | [
"You make a good distinction that the notion of a \"chemical imbalance\" being a simple cause of mental illness is based on dualism. It seems to relegate mental illness to the same category of a vitamin deficiency that can be cured merely by swallowing a pill; the propagation of this fallacy is causing huge harm to... |
[
"Could pure iron become a bose Einstein condensate at extremely low temperatures?"
] | [
false
] | null | [
"Unlike stated in a different answer, by far most of the naturally occurring iron is bosonic (about 98%) and thus could totally form a BEC.",
"The difference to Helium-4 is that iron is a metal, which indicates already that the interactions between iron atoms are very different from interactions between helium at... | [
" Bose-einstein condensation is a behavior of low-density boson gas at extremely low temperatures.",
"Read more about BEC here: ",
"https://scholar.harvard.edu/files/schwartz/files/12-bec.pdf",
"Edit: As pointed out by ",
"u/abeinszweidrei",
", the majority of iron-isotope has integer spins and that makes... | [
"A composite particle made from an even number of fermions is a boson. Bosons have integer spin and fermions have spin that's an odd multiple of 1/2; the common isotope of helium has four nucleons.",
"Interestingly, the total spin of a collection of particles does not have to be the sum of the spins of the indivi... |
[
"If you were in a spacecraft orbiting Neptune and looked out at the planet. Would there be enough light to see anything with the naked eye?"
] | [
false
] | [deleted] | [
"When they say 900x less light, it makes for an impressive figure, but the truth is that's only ~9.5 ",
"f-stops",
". A single f-stop represents a doubling of available light, but most observes wouldn't describe a single f-stop difference as 'twice as bright or dark'. A comparable comparison of exposure valu... | [
"The Sun is still pretty bright even when seen from around Neptune. It illuminates that planet pretty well.",
"Just how much light is there",
"Apparent magnitude of the Sun seen from Earth: -26.74",
"Apparent magnitude of the Moon seen from Earth: -12.6",
"Apparent magnitude of the Sun seen from Neptune: -1... | [
"I'm just using stellarium (free software) to simulate the visual magnitude of Neptune from the surface of Triton (one of it's moons). However, it's not that smart, and it paints a \"daytime sky\" that only has a meaningful definition on Earth. It doesn't calculate things based on Triton's distance from the sun and... |
[
"Do other animals find things 'funny' like we do?"
] | [
false
] | [deleted] | [
"Anticipation releases dopamine and defying the expectations of that anticipatory process releases even more dopamine.",
"This is why the punchline is at the end of the joke; it causes the brain to \"re-learn\" the whole beginning of the joke in a different context. More re-learning i.e. greater entropy causes gr... | [
"Crows have been known to play and act in a way that we would call \"silly\" for no other reason than amusment. There was a Nature special on it, and for further reading see if you can track down this journal:",
"Bekoff, Mark & Byers, John (1998). Animal Play: Evolutionary, Comparative and Ecological Perspectives... | [
"Along these lines: I work with captive, sanctuary-living chimpanzees in Africa. When one of them was recovering from surgery, she was confined to a small room to avoid opening her stitches. She would poke long pieces of hay out through the mesh and poke caregivers where she herself was ticklish. When the caregive... |
[
"How do enantiomers rotate polarized light?"
] | [
false
] | I've often heard that polarized light is rotated either right or left depending on chirality, but how exactly does this happen, like on a molecule level, how does one photon get rotated? | [
"One way to think of it is that plane-polarized light is composed of two components, one that goes like a clockwise corkscrew, and one that goes like a counterclockwise corkscrew, and because each component is going at the same frequency, the circular parts cancel and the sum is just a linear oscillation. (",
"h... | [
"Although we have good theories for explaining the process of light travelling through materials, those theories are quite complex. (e.g. ",
"https://www.youtube.com/watch?v=CiHN0ZWE5bk",
")",
"Some materials interact with light differently depending on the polarization it has. You've probably already seen ... | [
"What does the enantiomer do? Why do some materials rotate the light while some do not?"
] |
[
"What happens to the biliopancreatic loop after a duodenal switch is performed?"
] | [
false
] | I was watching extreme bodies on netflix and they were talking about doing a . But what happens to the biliopancreatic loop and why do they leave it attached? I would think that it would be safer to just remove that section because it looks like it would have a chance of becoming blocked or dieing? | [
"The biliopancreatic loop carries digestive enzymes to the common channel so digestion can happen in that short length of small bowel. "
] | [
"It's attached at both ends... (By the way, I have a DS)",
"One end is attached to the bile duct pancreatic duct and the other is attached to the common channel."
] | [
"Even though its only attached at the one end?"
] |
[
"How to use semiconductors to built a light sensor?"
] | [
false
] | The catch is: it must be a sensor of a specific frequency (a narrow band) and you must be able to change this frequency without much trouble. | [
"I think that regular PIN photodiodes would have overly broad spectral response (at least 1000 nm). ",
"The simplest thing I can think of is using an array of different LEDs reverse biased to ",
"act as photodiodes",
". Each will respond only to wavelengths shorter than its emission spectrum (but I don't k... | [
"I think your last statement is most practical/efficient, and is how UV-Vis spectroscopy works, if I remember correctly."
] | [
"Diffraction gratings",
" are preferred over prisms in UV-vis."
] |
[
"How is it that pulmonary embolisms kill you, but you can live with one lung?"
] | [
false
] | Do embolisms in a single lung kill? If so, I gather it has to do with the increased resistance in the blood flow system, which messes up the heart. But then, how come you can live on one lung? I'd really appreciate explanations which don't use acronyms :) This has sort of been but the answers are in medical speak and I... | [
"A embolism on one side won't necessarily kill, in fact, if it is detected and treated it probably won't kill (I use \"probably\" very loosely). The only embolisms that definitely kill are massive bilateral emboli (\"saddle emboli\"), which cause such obstruction to blood flow, such increase in resistance to blood ... | [
"Pulmonary embolic disease occurs along a spectrum, within a spectrum of background disorders. So, a relatively small PE in a healthy patient will likley not even by symptomatic. Conversely, a small PE in a person with preexisting cardiac and pulmonary disease may be very serious. Since you've used the example of l... | [
"It's not a ventilation mismatch, it's a perfusion mismatch. PE will restrict perfusion to an area of lung long before it impairs ventilation to that section"
] |
[
"Is there a mathematical representation of how the three primary colors interact with one another?"
] | [
false
] | I was considering some very basic things about the three primary colors, and noticed a pattern. Combining two primaries will yield a secondary color. That secondary color is the opposite of the primary color not used in the combination. Ex: Red + Blue= Purple Purple is Yellow's opposite Blue + Yellow= Green Green is Re... | [
"I've been working with computer graphics a long time and for me colors are just vectors. Each component represents the amount of one primary color (red, green and blue). For example:",
"Red + Blue = Purple",
"would be represented as ",
"(1 0 0) + (0 0 1) = (1 0 1)",
"To get the complementary of color you w... | [
"I don't know about a mathematical representation, but you've got the primary colors wrong.",
"There are two sets of primary colors, one for the additive color model (things that emit light, like computer monitors) and one for the subtractive color model (things like dyes). The primary colors for additive color a... | [
"Suppose the three primary colors are ",
", ",
", and ",
". They can be RGB for additive models or CMY for subtractive models. It doesn't really matter what colors the symbols actually refer to. For simplicity of notation, let's use the additive model.",
"Adding two colors gives some other color, and it doe... |
[
"Why can an organ, like the cornea, lung, or a heart be transplanted but a body “part” like an entire leg or arm can’t be?"
] | [
false
] | I know very little about legal or illegal body organ transplants and trafficking. I assume one of the main problems is that you have to perform surgery very well, I would imagine it’s a difficult procedure, and you would have to have the organs maintained in between the transplant. But what really is the difference bet... | [
"The answer is: they can. It's just very difficult. The many difficulties include finding a donor, keeping the body part alive for long enough before everything can be connected, and doing the connecting. These problems are unique to each kind of body part due to the anatomy. However, as surgical techniques improve... | [
"Because they are wayy more complex",
"A lung can work on its own, it just needs some blood and a throat connected to it",
"A heart has just a few working parts",
"A arm has thousands of nerves and muscles that all need to be connected",
"and usually its not really important, you can live without a arm or j... | [
"People who receive transplants have to suppress their immune system for the rest of their life - this is a big risk. The surgery itself is not trivial either. If your heart stops working properly then you are probably willing to accept the risk. If you lose an arm or leg? You can live without an arm or leg.",
"I... |
[
"Tell us something you are aware of due to your field of science, that \"normal\" people do not know, and that has an effect on your life/behaviours."
] | [
false
] | Example: If you study food poisoning you may be reluctant to eat food prepared by someone else. Please elaborate if this is something you think everybody should know about, and if it is good or bad knowledge (above example might be both depending on how you look at it...) | [
"If you tell someone (for example, a teacher) how to do something in a way which is obviously superior to their current way (such as a new classroom assessment) then they will probably never use it. If you present it to them as something that works well for you personally, saying the words, \"When I do x, I find it... | [
"\"All Natural Flavors\" is bullshit. ",
"There's nothing safer about natural foods. It's the same chemicals you're eating that make your food taste a certain way. For example, almond flavor is just benzaldehyde. Whether it came from peach pits or was synthesized in a lab, you're still consuming the same chemical... | [
"Food is safer than it's ever been in the history of the world. At least in developed countries. Food science is responsible for making food so safe. Unfortunately, you only ever hear stories about outbreaks, so the public thinks that food is unsafe. They are mistaken. The CDC recently reported an all-time low in f... |
[
"Can the earth be thought of as alive? E.g. the 'Gaian' hypothesis"
] | [
false
] | Is it feasible to think of the Earth as an organism of sorts? It seems to me that the biosphere is sort of in harmonic balance with the rest of the planet, and seems to help regulate some of the physical properties of the planet (e.g. salinity content, atmospheric makeup, etc.) Is this just a problem of defining what '... | [
"As someone who's educated in artificial intelligence and other computer systems, I'm going to approach this from another angle -- since I'm not a natural scientist.",
"In system theory -- whether it be a technological, geological, or other sort of system -- the Gaia hypothesis is a ",
"negative feedback loop",... | [
"So...I don't really feel qualified to answer yes or no. It's a self-balancing, equillibrium-prone system. However, so are toilets and shock-absorbers.",
"Aside from complexity, I'd argue that the Earth is no more alive than any system capable of remaining stable under outside perturbations. Then again, I'd be te... | [
"The answer is both yes and no. There are several different spheres of the Earth: atmosphere, lithosphere, hydrosphere, cryosphere (sometimes part of the hydrosphere), biosphere, and anthrosphere (sometimes part of the biosphere). Clearly, several of these are not alive in the traditional sense of the word, however... |
[
"Do rainbows represent every color our eyes are able to see?"
] | [
false
] | null | [
"This color triangle is a computer representation (i.e. not 100% accurate depiction) of all of the colors that a person can see",
"http://www.eizo.com/global/library/management/cms/05e.jpg",
"If you trace from the right corner over the top to the left corner, you will see the colors of the rainbow in order, ROY... | [
"Definitely not. It isn't even a pure spectrum of visible light. Especially the colours towards purple are very smudged. More about colours of a rainbow ",
"here",
" and if you click at the stuff in the menu there are loads of information about the formation of the rainbow(s) and also other similar phenomena.",... | [
"Afraid not, there's no pink in a rainbow. No grey/white/black/brown either."
] |
[
"If photons are massless, how do they impart momentum to propel a light/solar sail?"
] | [
false
] | null | [
"Momentum is a property of any particle which is moving, whether or not it has mass."
] | [
"Would a theoretical graviton have momentum",
"Yes.",
"and devoid of mass how is momentum calculated for a particle",
"The momentum is related to the de Broglie wavelength of the particle by p = h/λ. The relationship between the momentum and energy is E = pc.",
"how does its momentum energy get transferred ... | [
"So like what is momentum then?",
"Momentum is a quantity which is conserved in physical systems which are invariant under spatial translations. If the laws of physics don't depend on where you're located, momentum is conserved.",
"It's a property carried by any particle which is moving. It doesn't really have ... |
[
"Is surgery harder on a more athletic person?"
] | [
false
] | I think this belongs here... I was watching a video of a lower leg amputation and wondered if it would be harder to perform on an athlete considering stronger muscles, tendons, bone density, etc. Is this the case? | [
"I'm not a surgeon, just a run of the mill medical student, but I've been involved in a lot of cases, mainly in the abdomen and thorax. ",
"The thing that makes cases difficult is obesity. Try doing a C-section on a lady with a BMI over 50. You have to go through 8 inches of fat before you even get down to the pe... | [
"Blood pressure is generally low in healthy people. Sedated heart rate has to be pretty low. If you put someone under the knife on a treadmill, it might be harder. "
] | [
"Blood pressure is generally low in healthy people. Sedated heart rate has to be pretty low. If you put someone under the knife on a treadmill, it might be harder. "
] |
[
"Is it possible to build a machine that constructs objects molecule-by-molecule?"
] | [
false
] | If so, what innovations could make this possible? Reddit is a giant think-tank, and I'm interested to see what people think. Storing the molecular blueprints for any visible object would be impossible today, but likely not so in the future. The concept of creating millions of nanoscopic "assembler machines" seems impra... | [
"You can't really just grab onto and manipulate a single molecule, at least by using any current technology.",
"Pretty sure that's inaccurate. ",
"For instance, in the late 1980s/1990, IBM wrote out \"IBM\" with individual Xe atoms on a Ni surface using an STM. AFMs can be used to stab, scratch (surfaces) and s... | [
"If you're actually really interested in learning about it I really recommend reading 'Engines of Creation' by Freeman Dyson. This book answers your question way better than I could in a couple sentences. The short answer is that we are limited by the small scale of a molecule (see QM). You can't really just grab o... | [
"3d printers can be made very accurate, using lasers to guide steams of polymers, printing a car model the size of a hair. ",
"http://www.youtube.com/watch?v=5y0j191H0kY",
"Higher resolutions require applied chemistry, using stronger shorter ranged chemical bonds more than weaker long ranged electromagnetism. T... |
[
"How many mutations can a virus have before it's considered a different virus?"
] | [
false
] | [deleted] | [
"Based on the methods of classification, it could really just be one mutation. As long as it changed the behaviors or properties of the virus enough. At the very least it would be colloquially referred to by a new (slightly modified) name.",
"This is a very informative read: ",
"https://www.ncbi.nlm.nih.gov/boo... | [
"A mutation that for example changes the spike proteins so they can't bind to ACE2 receptors anymore, and bind to something else instead would most likely be classified as a different virus right? Since it's method of entry and thus (maybe) mode of action will be different?"
] | [
"Quick reply before heading into lab, sorry for any spelling errors. The answer is not as easy or clear as one would think and how it is measured differs between which virus you are talking about, usually there are rules/systems.",
"For it to be a new \"virus\" and not a strain or subtype I would say it is a ques... |
[
"Why does putting your fingers down your throat make you gag, but eating doesn't?"
] | [
false
] | null | [
"There are two different reflexes at work. The gag reflex is a response to your body believing something is stuck in the pharyngeal cavity, the part of your throat between the back of your mouth and your airway/esophagus. What normally happens when you swallow is that the food/liquid reaching the pharynx triggers a... | [
"So if we shoved our finger even ",
". Would it trigger the swallow reflex instead?"
] | [
"No. Both reflexes are triggered at roughly the same point. The difference lies in what your sensory system is saying about what's happening in your pharyngeal cavity. If the sensory system says, yeah, that came from the mouth back here and needs to go to the esophagus --> swallow reflex. If the sensory system says... |
[
"Did the Ostrich ever have a flying ancestor, or does it have yet to evolve flight?"
] | [
false
] | null | [
"Ostriches definitely had a flighted ancestor! I have an ",
"answer on another post",
" that talks about the evolution of flight in dinosaurs, and birds are (for the most part) flying dinosaurs.",
"More than that, the current thinking is that flight was lost multiple times in ratites, the group that includes ... | [
"Was flight only lost once in penguins according to current thought?"
] | [
"As far as I know, the oldest known fossil penguin (",
") is flightless. It lacks some of the unique traits that penguins have, but it wouldn't have had the ability to fly. Beyond that, I'm not sure we understand penguins' transition to flightlessness. "
] |
[
"How do Fire Ant colonies go about splitting?"
] | [
false
] | I was reading about how Fire Ants were brought to my country, and I was wondering how lets say a few different fire ant colonies could turn into a few dozen, then a few million, when introduced to a new environment. | [
"Just as a taxonomic note, the term \"fire ant\" refers to roughly 20 or so new world species. I assume, however, that you are specifically talking about the Red Imported Fire Ant (RIFA), ",
" Is that correct? If so, I can tell you of several reasons for their rampant expansion into new territories."
] | [
"Oh, my apologies. I misunderstood. Let's see if I can get it this time around.",
"After a certain amount of time, the colony will shift from the ergonomic phase, in which colony growth is rapid and the production of new workers exceeds the the rate of death, and moves to the reproductive phase, which is characte... | [
"With ",
" (RIFA) there are a number of factors to consider, including:",
"Lack of natural predators: having been transplanted from their native Brazil/Argentina, RIFA no longer encounters natural predators, those that are adapted and capable of either defending against them or predating on them",
"Aggressive... |
[
"Why does plastic shipping tape emit X-rays when it's pulled from the roll?"
] | [
false
] | null | [
"First, this effect only occurs in a vacuum. In air, the gas molecules rapidly absorb the emitted electrons. Basically the reason xrays are emitted is because of the static electricity generated by separating the tape film from the surface below it. As the tape is pulled away, an electrical field is formed at the p... | [
"This is called triboluminescence, and even ordinary things like sugar crystals will give off light when scratched or crushed."
] | [
"http://www.nature.com/news/2008/012345/full/news.2008.1185.html",
"\"The leading explanation posits that when a crystal is crushed or split, the process separates opposite charges. When these charges are neutralized, they release a burst of energy in the form of light.\""
] |
[
"A Twin Paradox paradox - what if objects A and B are fully symmetrical (in size and movements) ?"
] | [
false
] | null | [
"but relative to A ... only B has left and come back.",
"doesnt your explanation then mean that the time-dilation logic has a fixed 3rd-party observer somewhere calling the shots or describing what is happening. unless, A is able to measure the acceleration he is undertaking. But that would mean something fixed a... | [
"but relative to A ... only B has left and come back.",
"doesnt your explanation then mean that the time-dilation logic has a fixed 3rd-party observer somewhere calling the shots or describing what is happening. unless, A is able to measure the acceleration he is undertaking. But that would mean something fixed a... | [
"i know what is speed, and what is acceleration, but i have no idea what is \"inertial frame\"",
"and does this mean time dilation is more to do with inertial frames than speed?"
] |
[
"Saw this weird cloud on the way home. What causes this?"
] | [
false
] | Saw this on the drive home from work. Note that I am close to an active volcano as well as the coast. Looks almost like two conical clouds connected at their points. Any ideas? | [
"Looks like a ",
"lenticular cloud",
" to me."
] | [
"This is correct. It's caused by waves forming in the atmosphere on the other side of some topography, such as a mountain. So imagine air moving across a mountain range, it forms a wave due to the interference of the mountain (actually, we model the atmosphere as a wave anyways, but I digress). The air can't go thr... | [
"http://www.kirainet.com/images/fujilenticular.jpg"
] |
[
"Why does the SNRI Venlafaxine (Effexor) cause memory impairment?"
] | [
false
] | It has a very high incidence of failing memory as a side effect compared to other anti-depressants. There's a lot of horror stories about it lasting long after the drug is withdrawn. Why is this? What's the mechanism? Would there be a way to reverse it? | [
"Well, I'm not completely up to date on the most widely-prescribed AD drugs, but one difference between venlafaxine and other commonly-prescribed antidepressants like zoloft/prozac is that venlafaxine blocks reuptake of both serotonin and norepinephrine transporters, whereas SSRIs mainly block serotonin exclusively... | [
"Thanks for the reply. So would these gene effects persist after the drug treatment was ended or would they gradually revert back to their 'natural' expressions? "
] | [
"That's unclear, but I think it entirely depends on the gene you're looking at. The body of literature on molecular mechanisms underlying AD has pretty conflicting results at times for whatever reason (not all published data is created equal), so it's hard to draw any universal conclusions. There are definitely gen... |
[
"When a heavy nucleus breaks apart, the two resulting nuclei are more \"Tightly bound\" than they were before, but why does this mean they have less mass?"
] | [
false
] | [deleted] | [
"Tightly bound means that it takes a lot of energy to separate something into its constituent particles, and since E = mc",
", this means it gets heavier when it is separated than when it is bound. If it gets heavier when separated, then it must be lighter when bound. In other words, binding energy is negative be... | [
"iirc there are some neutrons left after the fission reaction that get expelled with a certain energy? the initial heavy atom splits into two smaller atoms that in sum have a smaller number of neutrons, so the remaining one(s?) get ejected and contribute to the decay of other nuclei. ",
"It has been a while since... | [
"iirc there are some neutrons left after the fission reaction that get expelled with a certain energy? the initial heavy atom splits into two smaller atoms that in sum have a smaller number of neutrons, so the remaining one(s?) get ejected and contribute to the decay of other nuclei. ",
"It has been a while since... |
[
"How do we know what chemicals reside on other planets from just viewing them?"
] | [
false
] | One sometimes hears that a planet may have rain that consists of diamonds, or that a planet does not have breathable air etc. made up of some poisonous gas.. how is this determined by astrophysicists? | [
"The \"rain that consists of diamonds\" has not been observed, that's just a guess based on what might happen if a planet contained mostly hydrocarbons. ",
"The \"breathable air\" and \"poisonous gas\" scenarios are rooted more in actual observations. In very rare cases, a planet passes in front of its star and... | [
"Ok, so...",
"When light from a star is viewed through a spectrograph, absorption spectra appear as a pattern of dark lines in its spectrum.",
"Each element and each compound creates a unique pattern of dark lines at very specific locations in the spectrum.",
"Now, those locations can change due to Doppler sh... | [
"\"red shifting\"",
" relates to the speed of an object rather than it's distance (although these two things are related due to cosmological expansion). ",
"I'm not an astronomer so I don't know exactly how it's done, but I would speculate that you don't necessarily need to know its distance or speed to hypoth... |
[
"In layman's terms, could someone explain to me the purpose of the inflammation response?"
] | [
false
] | It recently sprained my ankle - the latest in many injuries and it occurs to me that with virtually every injury, inflammation is undesired and vigorously counter-acted. But we must've had a reason to evolve it. Or is it just some kind of atavistic throw back? | [
"There are many different types of cells that make up the Immune System. Some of these are always around, just hanging out in tissues and in the blood. Others are in a kind of dormant state and have to be activated. When you injure yourself, the immune cells that are in the immediate area start to send out signals ... | [
"Inflammation is a very complicated concept in medicine, as you pointed out it can be bad as it can be useful.",
"Inflammation is a process that is triggered when any tissue is subject to injury. This injury can be in form of trauma, hypoxia (lack of O2 as in myocardial infarction), autoimmune diseases (rheumatoi... | [
"Hi! Yes, you're right that oftentimes an inflammatory response can have a more detrimental effect than a helpful one. But this is the price we pay for having such an incredible repair and defense mechanism built into our bodies. It's like having an alarm system in your house that is a bit too sensitive and goes of... |
[
"How long would it have taken for the moon to coalesce into a sphere after it was separated from the earth?"
] | [
false
] | null | [
"Can I add a request? History Channel's \"The Universe\" claims that the moon formed in just a few months after the Big Splat. How can that possibly be true?"
] | [
"http://en.wikipedia.org/wiki/Giant_impact_hypothesis",
"This is what wikipedia's article has to say about this:",
" ",
"Unfortunately the statement is not directly sourced, so I don't know it's validity. "
] | [
"Whichever one states that the moon formed from a mass of rock torn from the earth as a result of some massive impact early in its history..."
] |
[
"How did mines of minerals on Earth formed?"
] | [
false
] | My understanding is that all elements are formed by nuclear fusion in collapsing stars which then explode, dispersing all kinds of atoms in clouds. Then these clouds condense and eventually form planets. But then intuitively, I would expect planets, at least in the early phase, to be like a random collection of atoms, ... | [
"There are ",
" of different ore deposit types, each the result of different and specific processes. But you have an important insight: without ",
" peculiar acting on the Earth to concentrate some elements in a specific place, all you should expect would be pretty homogeneous rocks. In that view, ore deposits ... | [
"Well technically, mines and quarries are man made. But regarding why minerals are aggregated in certain areas and not evenly distributed, that's because the conditions that lead to their formation are localized. The ore or mineral deposits that we mine do not date back to the the original formation of the planet... | [
"Great answer! Thank you!"
] |
[
"If I get a flu shot one year for a specific strain of Flu, like H1N1. Why would I ever need a vaccine for that strain again?"
] | [
false
] | I understand you need flu shots every year because different strains of the virus circulate every year, but eventually shouldn't I be immune to all of them from receiving flu vaccines? Why does a vaccine that protects against H1N1 in 2015 not protect against H1N1 in 2019? | [
"The people who claim that the problem is that flu mutates yearly are more wrong than right. Influenza does mutate, and that leads to the problem of needing to regularly update vaccines, but it’s not yearly. The H1N1 component of the vaccine, for example, wasn’t significantly changed between 2010 and 2017. The H3N... | [
"Why does our immunity to influenza wane so quickly when other immunity doesn't (e.g. the shots you get as kid and last for 15+ years)?"
] | [
"This is completely wrong. Zoonotic viruses only enter the human population on very rare occasions; it has absolutely nothing to do with why influenza vaccination needs to be given annually. Almost everything else about this comment is also wrong. The virus doesn’t mutate more in pigs or birds, the mutations don’t ... |
[
"what's the smallest particle that can produce light?"
] | [
false
] | null | [
"Elementary particles can produce light."
] | [
"thanks for answering!",
"what kind of light does an elementary particle produce? is it visible light like from an element?"
] | [
"It depends on how it's produced. But any charged particle can produce ",
"bremsstrahlung",
", which has a continuous spectrum. So it could be radio waves, it could be visible, it could be gamma rays, etc."
] |
[
"Does the heart really 'skip a beat'?"
] | [
false
] | "I was alone in my house, when I heard some movement behind me my heart skipped a beat. When I turned around it was really the cat." - My girl friend was telling me over the phone. I know the feeling but is the heart really 'skipping a beat' ? | [
"The heart can \"skip a beat\". The most \"elegant\" example is probably the second-degree atrioventricular block type 1. Check out this EKG result from wikipedia: ",
"http://en.wikipedia.org/wiki/File:Type_I_A-V_block_5-to-4_Wenckebach_periods.png",
"\nTake a look at the three bottom lines. Without getting int... | [
"Yes, it should be extrasystole. Patients having up to 200 asystolies a day would drive the doctors crazy ;)"
] | [
"The supraventricular asystole is in fact a premature contraction of the heart muscle",
"Did you mean \"extrasystole\" here?"
] |
[
"Where does Australopithecus/Homo Floresiensis fit into the evolutionary tree?"
] | [
false
] | Was Floresiensis a descendant from Australopithecus Africanus or Homo Erectus, or was there some other underlying; perhaps pathogenic cause of 'The Hobbit' enigma? | [
"We can't know with absolute certainty how all these hominin fossils fit together in a family tree. Mostly we look at morphology, particularly the brain size, and some behavioural traits, like tool cultures, to help us define where species distinctions should be made. Again, its hard enough for us to delineate livi... | [
"How do you explain the substantially smaller brain size of Floresiensis when compared to H. Erectus? The brain and skull can be shrunk due to the island effect; however only to a certain extent. Floresiensis had the brain size of 400 cubic centimeters (roughly) and Erectus 600. People who suffer dwarfism don't hav... | [
"People that suffer dwarfism also ",
" Homo floresiensis. They ",
" have they adaptations that reconfigured their brains into a smaller space. You're comparing two different organisms (again) in a comparison that is not valid. In your other post you compared Australopithecus to H. floresiensis when these two sp... |
[
"following from the 700tb stored in a gram discovery, how long would it take to actually sequence that out."
] | [
false
] | didn't say in the , but what would the theoretical read-speed be on that (to sequence it all out) i'm no scientist but if i remember freshmen bio, sequencing takes a very long time, and i thought a gram of DNA is a lot. | [
"Yes a gram of DNA is a lot. When you sequence DNA you're usually starting with less than 1 ug (microgram), so less than 1 millionth of a gram.",
"700 terabytes = 5600 terabits, so that's 5600 terabases of DNA. The highest throughput DNA sequencing machine is, I'm pretty sure, the ",
"Illumina HiSeq 2000/2500... | [
"First, the title of that article is a bald lie and it should be taken down from ",
"/r/science",
". They actually only stored less than a megabyte of data, but there were billions of copies of it.",
"Second, we have high-throughput sequencing now, so what they did (one HiSeq lane) would cost over $1000 for r... | [
"Well, it took 10 years and 3 billion dollars and a worldwide effort to sequence the human genome for the first time in 2003, and 10 years later we can do the equivalent in 11 days (less actually if you just want one genome) for a few thousand dollars with one guy sitting in a lab with a few machines and a computer... |
[
"What is the physiologic difference between whispering and speaking in your regular voice?"
] | [
false
] | Or is there no real difference and I'm just an idiot.. | [
"Take one hand and put it on your neck, palm on the front of your throat. Now, say \"I am speaking louuuuuuuudly.\" You'll feel a vibration on your hand. That's your vocal cords flapping around in your neck. Try it again, but whisper. Where before you were pronouncing vowels with your vocal cords, now your vocal co... | [
"P and T don't use vocal cords. Pay close attention to how the B and D sound when you whisper. If you're really whispering, here is no vocalization. However, because you know what you're saying, your brain will fill in some of the gaps. Whisper the words \"pat\" and \"bat\" back and forth a few times. Are you actua... | [
"I can whisper b,p,d and t just fine without using my vocal cords. I agree with your first paragraph though."
] |
[
"If the mantle of the Earth is liquid iron, how is the core solid iron if it is much hotter than the mantle?"
] | [
false
] | What makes this possible? | [
"The mantle is not solid iron; it's dominated by silicate minerals like pyroxenes, olivines and a range of others depending on the pressure and temperature conditions at a given location.",
"The inner and outer core are both predominantly iron, and the reason for the phase change is simply that the solid arrangem... | [
"To add to that, the solid inner core is growing all the time. Iron, being much denser than silicates, sinks through the mantle to the core, as this happens, the pressure causes some of the liquid iron at the inner-outer core boundary to crystallize and solidify. A result of this is it gives off it's heat of fusion... | [
"One of the other ways in which the inner core is growing is the crystallisation, or freezing, of the outer core as it convects heat into the mantle and then the crust. There was a paper written in 2005 by Professor Hiroshi Shimizu from the Earthquake Research Institute at the University of Tokyo, \"",
"On crysta... |
[
"Why does this work?"
] | [
false
] | So I was reading that rage comic on f7u12 and was wondering if I could get a clear explanation as to why this works. | [
"-- Non expert, just providing food for thought until someone better qualified comes along --",
"Do you know for sure that it works? Would be a good thing to test experimentally :)",
"Car keys broadcast at ",
"~400 Mhz",
", so I would ",
" that your head functions as an antenna at these frequencies.",
"... | [
"It could be that the water in your body/head acts as something like an extended antenna (much like standing next to a radio sometimes improves its reception).",
"Also, holding the key upwards instead of pointing at the car exposes the sides instead of the tip of the antenna, which may give a better signal streng... | [
"The amount of iron in a human is so very tiny that it wouldn't really make a difference. Also, it's in haemoglobin molecules, not in pieces of iron, so it isn't conductive. The conductivity of metals arises from the fact that when they are just a piece of metal there are extra electrons knocking around in the meta... |
[
"Is there an accurate method of testing the percentage of urine in a swimming pool?"
] | [
false
] | I'm a writer and I think a great story would be to establish a sort of "average" urine-pool ratio. Obviously it depends on the size of the pool, the filtration methods, the amount of people in the pool, etc. But let's say I chose 10 swimming pools in my area, then took samples from each at different times on different ... | [
"There are definitely ways that would allow you detect almost anything in a pool. For example mass spectrometry instruments are routinely used to find trace amounts of contaminants in our water supply. These sorts of instruments are expensive however and you would usually only see one at a university.",
"It might... | [
"Also, sweat contains urea so that couldn't be used to establish an accurate urine measurement. I don't know what you'd use for that, maybe some biologist can weigh in on chemicals unique to urine."
] | [
"Who knows, maybe some undergrads in an analytical chem class would want to take a crack at determining urea concentration in a sample of pool water ? Sounds like a good time to me ",
"Edit: just saw the comment above mine about urea also being in sweat. Guess you'd have to find another analyte. "
] |
[
"Does gravity affect electricity in any way?"
] | [
false
] | Gravity will pull the electricity down into the p... | [
"Considering electrons have mass, they are in fact affected by gravity. I imagine that because the mass of them is so small, the gravitational effect on the electron is so small. Therefore I wouldn’t expect it to have any effect on the functionality of things such as ICs. Feel free to elaborate if I’m wrong."
] | [
"If the calculations in this paper:",
"http://journals.aps.org/pr/abstract/10.1103/PhysRev.168.737",
"are correct, then the gravitationally induced voltage between the top and bottom of a 1 meter tall conductor is of the order of microvolts, so the effect of gravity on electrons is maybe measurable (barely), bu... | [
"Certainly not in that way. An electric current is electrons flowing in a circle - the amount of electrons flowing upwards and downwards is the same.",
"You can find some indirect effects, e.g. gravity affecting the motion of objects or forces in the objects which then affects electric currents. Piezoelectric mat... |
[
"Imagine an object in a huge sling. If you swung it around fast enough, and then let go at an upward angle, would it be possible to launch it into orbit?"
] | [
false
] | If you could, it seems like you'd be able to do the spinning with magnets, and then not have to deal with rockets. But I know way more about science fiction than actual science, so I'm sure there's some reason this wouldn't work. | [
"I just have to ask: why do you so freely mix English and metric units here?"
] | [
"If you're referring to sending astronauts to space by this means, then someone would have to fly up in a shuttle after them to sponge up their remains. The g-forces would kill a person."
] | [
"But orbital velocity is only 71% of escape velocity."
] |
[
"How did the idea of the atom advance beyond a theory? (other questions inside)"
] | [
false
] | Hi , I'd like to get a better understanding of atoms. How was this idea proposed in the first place, and how did they end up proving it? Was the atomic bomb and nuclear bomb the first instances of being able to smash/slice an atom? I've also noticed that for many elements they have the same amount of protons/neutrons/e... | [
"Atomic theory came from chemistry, from the realization that there must be little indivisible bits of each element. (Actually atomic theory is often said to go back to antiquity and the Greeks, but that's a bit misleading, because until the 19th century it all amounted to little more than \"I bet stuff has bits in... | [
"Let's be clear, your question is really, \"How did atomic theory advance beyond a hypothesis?\""
] | [
"Theory isn't a pejorative in science."
] |
[
"Question on Thermodynamics and Body Temperature Regulation"
] | [
false
] | [deleted] | [
"a) No\nb) No\nc) Your body's narrow survivable temperature range is not because of water boiling- it is because proteins denature. Enzymes and proteins require extremely specific conditions, including temperatures, to remain in their native conformation and function. All of your body's functions and chemical react... | [
"Pressure isn't as large a concern due to the nature of the forces involved. Sure, you are talking about a lot of pressure, but these proteins are molecules within their own special forces. You are not just pushing on one side of the protein either, you are pushing on all sides of it as well. Thankfully it really i... | [
"*",
"not true about the chamber at 70 degrees centigrade.",
" At least not true about an immediate death.",
"we know that if you stem into a chamber that 100 degrees centigrade, the water inside you will begin to boil. ",
"Not so true. Water will boil at 100 degrees celsius ",
" That is the key point... |
[
"Is there a material or theoretical material that would be strong enough to be cast into extremely long solid beams that could build a large beam type bridge (say the length of the Golden Gate Bridge) without any sort of supports?"
] | [
false
] | [deleted] | [
"Coming from just a very basic mechanics standpoint...",
"The span that a solid beam can withstand is proportional to its width. You linked to the Peace Bridge, and that bridge supports itself by transferring the stresses through the helical steel structure. In that way, the relevant structural \"width\" is the... | [
"Simplistically, let's look at tensile strengths as listed on Wikipedia.",
"So yes, there are materials that would offer far greater capability than common structural steel."
] | [
"$$$ None of that would be economical on such a scale as the golden gate, but in theory, I agree there are many higher capacity materials than structural steel."
] |
[
"How much does lifestyle affect offsprings genetics?"
] | [
false
] | [deleted] | [
"Long story short, what you're asking about is the field of epigenetics. ",
"Traditionally, it was understood that only alterations to DNA sequence, the order of nucleotides that codes for proteins, was heritable. So, if there was no changed to the nucleotide sequence, there was nothing to pass on, no heritabil... | [
"Welllllllllllllllllllll....maybe not quite.",
"You've done a great job explaining the traditional understanding of genetic heredity. However, the traditional understanding isn't the whole story. It turns out that, actually, a parents lifestyle can impact the genetic expression of offspring. This is the field ... | [
"Thank you for clarifying! ",
"Would these changes be heritable to the offspring's offspring? Or would a different lifestyle reverse the changes? If so, is there a certain point where the lifestyle has been consistent enough through generations that it changes the DNA?",
"And could you break down what methylati... |
[
"Why did it take humans so long to discover agriculture? Why did we not discover it in the last inter glacial period?"
] | [
false
] | I googled something along the lines of this and only founded it posed as an open question on a khan academy page: | [
"Why agriculture originated when it did is a pretty mysterious thing and there's no real answer yet. That said, I suspect the answer had ",
" to do with population density. Human population density slowly increased leading up to the agricultural revolution...it may have just been too low in previous interglacia... | [
"Perhaps the megafaunal extinctions were an added incentive for a more reliable food supply."
] | [
"We are talking about a gap of thousands of years in that case though."
] |
[
"How much ( min/max ) genetic information do I share with my cousins, if our fathers are identical twin brothers?"
] | [
false
] | I'm curious, they look the same despite having lived more than half of average lifespan and people who don't know them very well still confuse them. I'm going to guess that way more than a regular half-sibiling, however whats also intrigueing is how much genetical information do the twins share, if they are identical ?... | [
"I'm going to guess that way more than a regular half-sibiling",
"Chances are you've guessed wrong. Your genetic relatedness with your father's identical twin brother's children is the same as for a half-sibling.",
"however whats also intrigueing is how much genetical information do the twins share, if they ar... | [
"Most of these answers are right and wrong. They are right in the sense that they're talking percentages of ",
" DNA. Seeing as humans share ~96% of DNA with chimpanzees, remember to take into account that the 50%s and whatnot are 50%s of the small percentage of DNA that ",
" shared with a vast majority of othe... | [
"The probably not very useful answer to the first question between 0% and 100%.",
"0% and 100% are statistically very unlikely but possible. ",
"your identical fathers sperm could have split their genome exactly the opposite way so that they don't share anything."
] |
[
"How does the brain differentiate between music, normal sounds and cacophony?"
] | [
false
] | I understand that people have different musical tastes, but clearly there is a difference between what we hear is music and what we don't. Is there any neurological explanation for how music exists? Furthermore, how do you qualify good vs. bad music? | [
"More accuarately, pattern recognition."
] | [
"Fantastic question. I will answer this tomorrow in detail when I have more time. I will edit this comment here."
] | [
"Pardon me, but I was searching for music-related questions in the subreddit, and this one intrigued me. Is there any chance that you could come back and edit with an answer?"
] |
[
"How to doctor's know they removed 100% of the cancer in someone after surgery?"
] | [
false
] | null | [
"In general they don't, which is why cancer surgery is such a crap shoot. ",
"But there are special cases in which the cancer is contained inside some sort of membrane. In a case like this, if the surgeon is able to remove the lump with the membrane intact, he can be confidant he got it all. ",
"As long as ther... | [
"In truth though you can't be 100% certain you got every last bit of it, so they make cut into the good tissue surrounding a tumor. Like cutting out a circle in the wall around a dart board to make sure you get the bullseye out. But it can't necessarily be detected at the cellular level during surgery so its possib... | [
"As other posters have said, they are rarely or never 100% sure, but even so determining whether and how much cancer has remains is an important aspect of many cancer surgeries. One procedure of which I am aware is ",
"Mohs surgery",
". In that technique small section of suspected cancerous skin tissue are remo... |
[
"Why particle accelerators are so huge? Wouldn't be possible to crush particles in a smaller and spiral structure?"
] | [
false
] | sorry for the dumb question, my knowledge of electromagnetic fields is restricted. | [
"The vast majority of accelerators are not that big (they can fit in a garage). It sounds like you're specifically asking about the few very large colliders around the world. So why are ",
" so large?",
"You use a collider rather than a fixed-target machine when you want to reach higher energies. Kinematically,... | [
"They don't need to reach such high energies, so they don't need to be big."
] | [
"Oh, that was fast.",
"Thank you very much for spending that time answering my question, I really appreciate that.",
"But what about the smaller ones which fit in a garage? they use a different mechanism or just a stronger magnetic field?"
] |
[
"Is wrinkling caused directly by worsening skin health due to aging skin, or is it simply a by-product of movement of skin over time?"
] | [
false
] | null | [
"Human Body",
"Human Body "
] | [
"Human Body",
"Human Body "
] | [
"Human Body"
] |
[
"What happens to the blood vessels that run through our limbs when we bend or twist a joint on those limbs?"
] | [
false
] | null | [
"Your blood vessels have some pliability to hem but not much. There are many instances in traumatic joint and extremity injuries where a vessel can be ruptured by the twisting and pulling force or severed by hard tissue like bone or cartilage. One of the things we look for in traumatic extremity injuries is whether... | [
"Your blood vessel twist and can accomdate this to an extent. Go to far and you risk damage. Interestingly part of the reason you cant twist your neck all the way around is related to this. In fact owls evolved a very interesting adaptation to the blood vessels feeding their brain which allows them to twist their h... | [
"Puts a whole new meaning to the “Golden Hour” and “Platinum Ten” when you’re at terminal velocity. "
] |
[
"Has anyone ever noted an evolutionary change between REALLY old trees and young members of the same species?"
] | [
false
] | I was reading about "The Senator" from a comment on an old tree that got cut down my poachers in Canada, and it made me wonder. Since some trees are thousands of years old, like (and some clonal colonies like ), is it possible that the modern versions of these display any traits not found in the older (but still alive)... | [
"From an evolutionary standpoint, those trees aren't that old. I'm too lazy to dig up the rate of evolution in plants, but they probably are over millions of years rather than a few hundred (or even thousands). These trees are old compared to human lifespans, but they're not \"really old\". And remember, these tree... | [
"What does that mean?"
] | [
"You might see a change in the hardy-weinberg equilibrium. You can see that in less than a hundred years. It won't be huge, but you can see it."
] |
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