title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How long must an image be displayed for a human to recognize that an image was present?"
] | [
false
] | I've often heard the answer to this is on the order of 50ms. That is, on a blank screen, an image must appear and remain present for at least 50ms for a human to acknowledge that an image had been presented. However I am struggling to find any literature or research on such a boundary. Can anyone point me in the right ... | [
"Well, there are few related questions, but there's tons of research on the topic.",
"First I'll just give my rough understanding of the issues involved. The first thing to consider is how the image is presented can actually drastically effect if it is seen. So if it is a faint image you'll need to view it longer... | [
"Human consciousness is experienced in chunks of about 70 milliseconds. If you flash a blue image and then a red image each for 50 ms, you will see purple because your consciousness cannot keep up. ",
"Source: taking a psychology class in college "
] | [
"Thanks for all the info and especially the links! Super helpful.",
"So I was actually looking for literature on the ability of humans to see 'something' even though the work I'm doing involves analyzing that 'something'. Your third reference, unconscious perception, supplied a lot of help in both regards and was... |
[
"Do animals understand the changes that occur to them when they age?"
] | [
false
] | I live with my Grandfather and his dog is incredibly old. It's gotten to the point that if she wants to stand up, she needs someone to lift her up by her hips. Often, she will bark which is her cue that she needs to be lifted or go to the bathroom. If no one hears her barks she has no choice but to urinate on herself. ... | [
"Really I just want to say that I'm sorry your question is only getting negative responses. ",
"I may be able to be of some use though. Humans have a quality called metacognizance , which is taken very much for granted simply because its all we know. This trait is what let's be aware that we are thinking. Its tha... | [
"I really appreciate this comment. It's probably the closest thing thing to an answer I can get for this question"
] | [
"Many old people don't realize that they can't drive car safely anymore :)",
"I don't think that realizing that their abilities have diminished is beyond dogs. Especially because they are social animals and can get cues from humans. Change in social status from companion to someone who is nurtured might be very ... |
[
"How does a LASER Pointer draw a line instead of just a moving dot when I move it quickly back and forth?"
] | [
false
] | I bought a LASER Pointer to play with my cat and noticed if I move it fast enough the dot forms full circles or lines depending on the movement. Is it still just a dot and my mind is making it seem like a line or circle, or is something else going on? | [
"The same reason why you don't notice movies being single frames (at not even a terribly high rate). Processing time. The brain needs a while to make sense of input and takes shortcuts whenever possible. It will fudge over anything it misses, to make things look coherent, even when that's not what's really going on... | [
"We have a pretty large blind spot in our field of vision this happens with constantly"
] | [
"That's true for one eye but does a blind spot exist if both eyes are open?"
] |
[
"Why isn't something like a magnetic motor practical? If it is practical, why aren't they used more? What are they used for if at all?"
] | [
false
] | null | [
"Edit: I see what you are asking. By placing magnets in a circle around another magnet, you hope to cause the inner magnet to rotate perpetually. ",
"The Museum of Unworkable Devices",
" has an explanation of why this device does not function. The short answer is that the combined magnetic field of the magnets ... | [
"Yes, that is what I was referring to. Should have been more specific in my post, sorry about that. Thanks for the video though, I'll take a look at it."
] | [
"I am not sure what you mean by \"magnetic motor\", something like an asynchronous motor is a magnetic motor for example. It relies on induction and magnetic forces to produce useful work."
] |
[
"[Physics] if you cool the radioactive isotope to absolute zero, would it decay?"
] | [
false
] | in theory, at least. If I remember correctly I don't think you can cool things truly to absolute zero. Would the half-life change at a temperature very close to absolute zero? | [
"Yes. ",
"At low temperatures (meaning below even many millions of Kelvin) nuclear physics becomes pretty insensitive to temperature. The thermal energy becomes far far less than the energy of a nuclear decay, so virtually all nuclear physics happening on earth (and even in most stars) is all effectively happenin... | [
"0K means that the atoms in a substance don't vibrate.",
"This is also not true. Particles still move at absolute zero, they're just in the ground state."
] | [
"0K means that the atoms in a substance don't vibrate.",
"This is also not true. Particles still move at absolute zero, they're just in the ground state."
] |
[
"Will a cooled steel blade be sharper because the cooling causes the metal to contract, and if so could you make a blade significantly sharper by super cooling it?"
] | [
false
] | [deleted] | [
"The word supercooling actually means keeping it in a liquid phase below its freezing point. ",
"Here is an interesting video on supercooling",
". The water is already supercooled (it is below 32F / 0C), and then a slight perturbation results in runaway solidification. ",
"As for your question, the answer is ... | [
"Cooling it very quickly results in a less crystalline structure than cooling it slowly. A search for ",
"quenching",
" will give you more details. In chemistry terms, certain crystalline states are thermodynamically favorable, but by cooling very quickly you can prevent them from forming because the formation ... | [
"Honestly, I think the only \"breakthroughs\" you'll find (if you find any) would not be in the way of fabricating the steel but rather in how it is quenched/tempered since the way of making it has been found for the last hundred years. Metallurgy isn't something new to man, however finding a way to make some proce... |
[
"Is Crystallized Bismuth the Only Instance of Naturally Occurring Right Angles?"
] | [
false
] | [deleted] | [
"Cubic crystals are actually pretty common. Halite, aka table salt, also forms cubic crystals.",
"EDIT: ",
"https://en.m.wikipedia.org/wiki/Cubic_crystal_system"
] | [
"Lot of crystals have right angles. ",
"Here's one you've probably seen in a gift shop or something.",
"What's makes bismuth look weird is that it can form ",
"Hopper Crystals",
". Bismuth isn't the only material that can do this.",
"Hoppering is common in many minerals, including lab-grown bismuth, galen... | [
"Try stacking tennis balls together. You can only get right angles, or equilateral triangles."
] |
[
"Is baby weight at birth indicative of later frame size as an adult?"
] | [
false
] | If one baby is heavier than the other at birth but still within the normal range, does that mean that baby will become a bigger framed/boned adult later? I found information that longer babies do become taller adults, but nothing about weight differences in the normal range (not talking about underweight babies). | [
"A lot of comments here without sources which are saying there is no association. A cursory pubmed search however suggests otherwise. e.g.",
"https://pubmed.ncbi.nlm.nih.gov/10206622/",
"In Danish army recruits",
"\"There was a strong positive association between birth weight and adult height\"",
"https://w... | [
"Birth length can be somewhat predictive of adult height but birth weight not really, both can be confounded by gestational age.",
"https://i.imgur.com/YNolxnr.jpg",
"FIGURE 2.: A, Mean adult height by birth length. B, Mean adult height by birth length, stratified by gestational age. C, Mean adult height by sta... | [
"That doesn't really answer OPs question though does it? ",
"OP has the info that longer babies make taller adults.",
"A longer baby/taller adult are typically going to weigh more than their shorter counterparts. ",
"I think what OP is asking, is about two babies of the same length at birth but different weig... |
[
"Why are COVID serology tests not recommended as a measure to estimate protection in vaccinated individuals?"
] | [
false
] | Presumably, if I have a lot antibodies for a virus floating around - I'd be better prepared (on average) to avoid infection, won't I? | [
"The concept isn't bad, and you can do this for some other viruses. But there are two technical problems with COVID serology for this use.",
"One is that we don't yet know a correlate of protection. That is, we don't know what level of antibody you need to be protected against infection. In concept, that's straig... | [
"Thanks for the beautiful answer, that's pretty much what I was wondering about. I have a risk factor, and tested very highly with regards to the reference. Putting variants aside, it seemed weird to me that amount of antibodies won't simply correlate with protection. Indeed, I understand that's likely the case. Th... | [
"Because your protection level isn't just about how many anti-bodies you have knocking about, but your ability to recognise the infection early and produce more as well.",
"The latter is something that is harder to measure.",
"We still don't know if COVID protection relies on having a strong anti-body presence ... |
[
"Would there be a significant advancement in observation capabilities if we used VLBI like the EHT, but one of the radio dishes was on the moon?"
] | [
false
] | null | [
"Hi robb0688 thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the follow... | [
"Physics"
] | [
"Yes, there would be improvement. The Moon is sixty earth radii away and the baseline would increase by a factor of thirty (one earth diameter",
"to sixty earth radii). Correspondingly, the angular resolution would increase (at the same wavelength) by a factor of thirty. One can resolve",
"angles that are smal... |
[
"If a baby is born prematurely, does it develop like babies born around the same time or like babies conceived around the same time?"
] | [
false
] | null | [
"As no one from the actual neonatal world has chimed in yet, let me take a shot.",
"First of all, let's lay some groundwork. \"Premature\" is an umbrella term and describes a varied range of patients with extremely disparate severities of illness. Neonates in the earlier week ranges (24-28) tend to do more poorly... | [
"It develops like babies conceived around the same time. Doctors will adjust developmental goals based on gestational age rather than saying that the baby is behind. For example they use this with height and weight charts to help determine if the child is properly gaining weight. If the scale were not adjusted for ... | [
"That would depend on the constellation of developmental deficiencies in the individual patient. "
] |
[
"How did homosexuality come to be?"
] | [
false
] | null | [
"There is tons of non-hetero behavior in the animal kingdom. Gayness is not abnormal. The book ",
"Evolution's Rainbow",
" documents some of prevalence of the wide variety of genders and sexual orientations present in nature, and there is the whole interdisciplinary field of ",
"Queer Ecology",
". Moreover,... | [
"Maybe somebody will come along and give a full answer but you should really do a google search before asking. See ",
"here",
".",
"homosexuality isn't good because this let's the species die out",
"That’s clearly not true because there are still humans."
] | [
"If all humans became homosexual, we would die out. We haven't because the percentage of homosexuals is small"
] |
[
"What makes and erupting volcano like the 1883 eruption of Anak-Krakatau loud enough to be heard at great distances?"
] | [
false
] | null | [
"Things in general that make an eruption explosive:",
". This is chiefly water, though also carbon dioxide, sulfur dioxide and methane dissolved within the magma. As this magma nears the surface the confining pressure is lowered, these compounds exsolve, formung bubbles of gas (which means a large volume increase... | [
"It's a huge explosion so basically as the air expands away from the volcano it makes a very loud noise that can be heard at distances proportional to the yield of the explosion. Bigger explosion means the sound travels farther."
] | [
"Shockwave. When sound becomes too loud, it stops behaving like normal sound and becomes another type of wave called a shockwave. It travels faster than sound and eventually decays into normal sound waves, producing the characteristic \"rumbling thunder\" noise. Because it travels faster than sound, you can hear i... |
[
"Are humans (homo sapiens) closer to bonobos (pan paniscus) or chimpanzees (pan troglodytes)?"
] | [
false
] | And another question on the same note, given that bonobos are more socially-oriented than tool-oriented, and chimpanzees vice versa, which are we more akin to? | [
"They are equally distant. ",
"Bonobos and chimps share a common ancestor, which shares a common ancestor with us",
". ",
"Your follow up question is akin to asking which of your cousins is closer to you. Despite how one might seem “closer to you” or similar in some specific respect, and the other in a differ... | [
"We could count the number of gene differences between us and them. But that wouldn't be very meaningful because some genes are more important than others."
] | [
"I recently finished reading a very interesting book called 'Civilized to Death', by Christopher Ryan, which said that Humans were equally distant/close to both Bonobos and Chimpanzees, but closer to Bonobos from a cultural perspective. The point of the statement in the book is that people(Thomas Hobbes and those w... |
[
"Would our lives be much different if our planet were orbiting a HUGE star, but we were proportionally further away?"
] | [
false
] | We would have to be at a distance where our temperature was the same as it is now. I guess our year would be a lot longer, anything else? | [
"If it's a main sequence star, and much larger than our own sun then it would be a hotter star and emit a slightly different spectrum. It would look more blue. It would also have a higher luminosity. So we'd have to further away than we are to a star like ours. The distance and radiation could change the way the pl... | [
"This is making the assumption that intelligent life necessarily requires the same amount of time to evolve as we did. We can't really make that inference from one data point, especially not in a scenario with different conditions as in this post."
] | [
"The mere amount of time required for a planet to cool to temperatures where liquid water can exist is significantly longer than the lifetimes of many high-mass stars."
] |
[
"Do Dogs Have Episodic Memory?"
] | [
false
] | I hear conflicting opinions on this. Some say dogs have , but not . If this is the case, how do dogs dream? If a dog is dreaming, for example, about chasing a squirrel, wouldn't it have to remember seeing the squirrel first? (I am assuming that remembering images relies on this , but please correct me if I'm wrong). | [
"Go watch 'Bunny' the dog on YouTube. Has learned around 300 words, through the use of paw-activated buttons. Bunny absolutely has episodic memory, as well as long memory of the past, additionally, Bunny plans for the future and makes requests for things and events yet to come.",
"Bunny can relate the content of ... | [
"It's hard to fully confirm without a talking dog and perhaps also clearer definitions of what counts as episodic memory. But at least \"episodic-like\" memory has been confirmed in dogs.",
"https://www.cell.com/current-biology/fulltext/S0960-9822(16)31142-3"
] | [
"I dunno about the classification of dog memory and dream memory. ",
"Dreams are the brain's maintenance cycle. They aren't passive like a movie and they don't need to make ANY sense. A squirrel can just appear or something that reminds them of a squirrel. ",
"Squirrel, therefore chase. Chase therefore ball. Ba... |
[
"Why does donor blood not attack the recipients blood?"
] | [
false
] | A person with type O blood can't recieve blood from someone with type A blood because they will have antibodies that attack the red blood cells, however when done the other way the type A recipient can receive the type O blood. I understand that the blood is usually spilt into component parts, but from what I've been a... | [
"Type A blood has A antigens on the surface of the red blood cells, and anti B antibodies in the plasma. If you have A blood you can accept type O blood because it has no antigens on the red blood cells, but you cannot have type B because it has type B antigens on its red blood cells and you have type B antibodies ... | [
"You're confusing antigens with antibodies in the second sentence. Someone with type A blood cannot receive type B blood because they have type B antibodies, not antigens, in their plasma. Similarly with your fourth sentence."
] | [
"White blood cells aren't present in the packed red blood cells that we give. When we transfuse, we can put in orders for packed RBCs, plasma, or platelets. These components have all been separated out."
] |
[
"What is the selective pressure that has led to decreased sexual dimorphism in Homo Sapiens compared to archaic Homo Sapiens, Homo Erectus, and older hominids?"
] | [
false
] | Basically, I'm wondering why the size and physical appearance differences between the sexes have decreased in modern humans. Archaic humans and hominids have males that are much larger than the current males versus their female counterparts. However, I know this is just anecdotal nonsense, in my experience, males stil... | [
"First, yes there is a general trend towards sexual monomorphism in the genus ",
"Homo",
". Although, humans have been about the same (with local variation) since our speciation some 250,000 years ago. Thus when we discuss humans we are not talking about the past 10,000 years we are talking about our whole hist... | [
"other means of assessing fitness arose (ability to hunt, ability to protect, ability to care for infants...which may not necessarily involve being larger but perhaps smarter).",
"These qualities are easier to assess in a stable social group, so we should expect social species to be less subject to sexual-selecti... | [
"No? Vaginas are highly stretchable. ",
"The primary theory AFAIK in regards to penis size and our loss of penis bone is that it is a sign of fitness. Being able to maintain a large erection is a sign of cardiovascular health, which was probably very important in bipedal endurance hunters. The very fact that a hu... |
[
"If a grain of sand were the size of the Earth, how big would an atom be? How about an electron?"
] | [
false
] | null | [
"This is the kind of thing wolfram alpha is really useful for. Go plug in some queries like \"size of a grain of sand\", or \"size of the earth\", and I bet you'll be much more satisfied with what you find than someone spoon feeding it to you over here."
] | [
"Ok this is my quick back of the envelope calculation rounding to orders of magnitude to make it easier. Wikipedia says \"medium\" aggregate sand is on the order of 0.1mm, or 10",
" meters. The Earth has a radius on the order of 10",
" m so that's 10 orders of magnitude difference between them. If we scaled the... | [
"And still there are things smaller. Crazy. Thanks!"
] |
[
"Is an inertial dampener entirely science fiction? Or is there a theoretical way to actually make one?"
] | [
false
] | null | [
"Remember Newton's second (and first) law, F=ma. Changing the inertia (the resistance to acceleration due to a force) of an object is the same as changing its mass, so \"inertia\" and \"mass\" are basically two different words for the same thing.",
"So, inertial dampeners are just a piece of ",
"applied phlebot... | [
"So an example of a real world \"inertial dampener\" would be a shock absorber.",
"This is also basically how they are used in Star Trek. A device that absorbs acceleration and shocks that would apply to anything that the damper acts on."
] | [
"\"just fine, thank you.\"",
"I thought that was the response to asking how the Heisenberg Compensators in the transporter system work."
] |
[
"Could a powerful enough magnet suspend metal nano-particles in the air around it?"
] | [
false
] | Subquestion: if possible, do you think you could use it to capture radiation like, to some degree, telescopes and satellite dishes? | [
"Magnetic fields can definitely affect metal particulates, but I'm not sure what you're really asking. I think you may be implying some kind of maglev affect, in which case I can only say that I don't think there is any indication that such a 'metal dust blanket' would be possible to create."
] | [
"Well, I was actually thinking of how iron filament aligns to a magnetic field when a powerful magnet is placed near it on a 2-dimensional surface and was wondering if the magnet was powerful enough if it would happen in the air."
] | [
"It would, but they would only align themselves to the field. I guess the part of your question I didn't get was the 'suspend' part. If the particles are already in the air, the effect of the field may cause them to clump together on the magnet. They really wouldn't be held in place without multiple interacting mag... |
[
"How do things grow in eggs without air?"
] | [
false
] | How does a creature grow in an egg when there's no air circulation, no oxygen gained? How does the animal transition to air-breathing? Could it be sustained in an artificial egg indefinitely, and never start air-breathing? Where does all the energy for its growth come from? . Seriously, what is up with eggs, man? | [
"The answer is rather simple. ",
"Eggshells have tiny holes in them to allow gas exchange",
". Some species have leathery/gelatinous membranes instead of hard shells, which similarly allow gas exchange. Energy comes from stored protein and fat in the egg."
] | [
"If it's an egg that isn't normally underwater, yes. Fish eggs and amphibian eggs and such that get laid underwater will get plenty of oxygen underwater, but will dry up if you take them out, since they don't have the water-retaining shells of land-based eggs (after all, they don't need them). "
] | [
"So if I stick an egg underwater, it will die, even if I give it the heat it needs?"
] |
[
"Is it possible to have information less than a single bit?"
] | [
false
] | null | [
"Yes. For example, entropy can be measured in bits. A fair coin that lands 50% of the time each on heads and tails produces exactly one bit of entropy per toss. However, if you had a coin that wasn't fair, it produces a fraction of a bit of entropy.",
"See 2nd paragraph in summary: ",
"http://en.wikipedia.or... | [
"From an information standpoint, yes. You can have a base-1 counting system, tally points are a good example of that. ",
"Since you filed this under computing I should also clarify that digital computers exclusively work with electricity that is either above or below a certain voltage. Computer processors are des... | [
"And what about from a mathematics perspective? Is it possible to have less than two possible states?"
] |
[
"Why are the pictures of celestial objects from space never blurred out, if the bodies are in constant motion?"
] | [
false
] | For instance, a picture of Earth from the moon. I believe the Earth is rotating quite fast at 17 000km/h. Why are pictures never blurred but rather clear-cut? At those speeds wouldn't it just be a blur of white green and blue? How come we can see defined outlines of clouds, sea, and land as if the Earth were still? | [
"You know how you're driving on a highway and the road signs right next to the road whizzes by quickly, the mountains in the distance look like they're not moving? This is called ",
"parallax",
". The very same distance subtends a smaller angle in your field of view the further away it is - so for a given linea... | [
"They are moving very fast but their velocity relative to our field of view is incredible small. Think about an airplane. If one flew past you less than a meter away it would seem very fast, but if you look at one flying far above it takes a while to get through your field of view. "
] | [
"If you were on the moon, the smallest object you could see would be about 120 km wide. The Earth revolves at about 450 km/sec. Therefore, the object would appear to move at about three times it's width per second. That apparent movement is not very fast."
] |
[
"How unique are fingerprints, really?"
] | [
false
] | Has anybody ever actually worked out the math on this? How many possible configurations and arrangements of loops and whorls could there actually be? EDIT: To make this a bit more of a manageable problem, let's assume we're using current levels of fingerprint analysis used for prosecution of crimes. | [
"Fingerprints isn't just about loops, arches and whorls - those are just overall patterns. A full fingerprint analysis involves noting the location of each minutiae - the ridge endings, bifurcations, deltas, and even pore locations. It is their relative location to each other that is used to individualize prints.",... | [
"A good example being the coastline paradox."
] | [
"http://en.wikipedia.org/wiki/Coastline_paradox"
] |
[
"Will a bone marrow transplant lead to a tranplantation of ones specific immunity? (and/or can chemotherapy/radiotherapy lead to the loss of ones specific immunity against previously exposed pathogens?)"
] | [
false
] | null | [
"Yes. Depending on disease,that might actually be the point of the transplant--to completely replace your failing immune system with a healthy one. Even if that is not the point, it will be necessary. The radiation and chemotherapy kill off your immune system so it doesn't attack the donor cells. Then, if everythin... | [
"Yes, this is the case regarding stem cell transplants. An interesting thing is that people who get bone marrow/stem cell transplants usually have to get their vaccinations redone afterwards since they've wiped their own immunity.",
"As for chemotherapy, there's a debate--the normal consensus is that the immune s... | [
"Bone marrow isn't able to construct memory B and T cells--the memory B and T cells are formed from already mature B and T cells, and then just kind of sit around waiting for the same infection to reappear. Memory B cells do hang out in the bone marrow, as well as the spleen and lymph nodes.",
"Memory T cells app... |
[
"What is the actual evidence we have regarding the 'cardioprotective' and vascular benefits of alcohol? Is one alcoholic drink per day truly beneficial, or are the \"studies\" people refer to simply failing to control for confounding variables?"
] | [
false
] | For example, partaking in one drink per day may actually imply one has the socioeconomic status to afford alcohol, yet the self-discipline to limit to one drink. Also, "dosing" oneself a glass of, let's say, red wine every day for the sake of 'health' implies some degree of health-consciousness. So, what is the truth? ... | [
"Below is a summary I pieced together from ",
"UpToDate",
":",
"Several factors should be considered in interpreting the evidence that relates alcohol consumption to cardiovascular risks and benefits: uncertain verification of alcohol use, multiple possible confounding factors, and differing definitions of a ... | [
"Great reply! this is perfect"
] | [
"I'm quite familiar with Framingham. Alcohol is not one of the variables we use clinically to calculate 10 year risk."
] |
[
"Say aliens had technology similar to ours and slower-than-light spaceships that were about as big as a Star Trek starship. Regular people can help sift data from the Kepler space telescope. Is there any kind of data that Kepler could detect that would scream \"SETI\"?"
] | [
false
] | a) I understand that alien spaceships probably don't exist. I just think it would be fun to look for them, in case they did exist. b) My understanding is that SETI people are already using radio telescopes to look at the planets Kepler has found; I'm just wondering if there could be signs of intelligent life that would... | [
"Kepler looks at stars to see if they occasionally dim when a planet goes in front of them. A Star Trek ship is about a kilometer will make approximately zero difference when moving in front of a star.",
"The SETI project isn't based on extrasolar planets, but rather searches radio bands that are expected to be i... | [
"If they have spaceships the size of Star Trek star ships, then their technology is not similar to ours. Not by a long shot."
] | [
" is too insignificant an object to be reliably detected from fifty light-years away. The answer to your question is absolutely not, no chance whatsoever."
] |
[
"How do scientists control and maneuver the mars rover when it's so far away?"
] | [
false
] | How does the mars rover receive the signals that are being sent to it from earth? | [
"They send a series of commands along the lines of \"go forward 1 meter\" or \"move drill to such-and-such position\" and then wait for the response. It's why the rovers are so painfully slow. Round trip time is over an hour. As far as receiving the signals, it has a high gain antenna that it keeps pointed at earth... | [
"Most of the communication is done via UHF relay to spacecraft in Mars orbit, rather than \"Direct-To-Earth\"."
] | [
"The procedures are more complex than the other user makes it. Rather than have very fragmented, step-wise instructions and delays, it's more a \"bulk\" transfer of instructions. You set out the task to be performed for, say, the day, and send those instructions. That's why the rover has its own navigation system t... |
[
"If you feel constant pain in a certain area, will the pain neutralize?"
] | [
false
] | I noticed the other day that if you bite your fingernail loosely and then slowly tighten the grip over a course of a few minutes, the ache almost goes away compared to if I'd grab a quick bite of it. | [
"Generally, no. Pain is detected by receptors called ",
". Every other kind (",
", ",
", etc) can become \"accustomed\" to stimulation, and will adapt to ignore it fairly quickly. Nocireceptors do not adapt and ignore incoming signals. It makes sense, as the body would not want to evolve an ability to ign... | [
"The particular constant pain can be \"neutralized\" however if a stronger painful stimulus is applied to the body.",
"Also, depending on the source of a pain, permanent nerve damage can occur (constant pressure, for example)."
] | [
"There's a lot more to pain than activity of nociceptors. Ultimately, pain is in the brain.",
"The classic \"Gate Control\" theory of pain proposed that pain is perceived as a ratio of nociceptive input to non-nociceptive input. After all, nociceptors are sensitive cells that might go off every time you're touche... |
[
"What is actually happening to color when sunlight bleaches something?"
] | [
false
] | null | [
"Not necessarily. The American flags placed on the Moon by the Apollo missions are, by this point, unidentifiable as such as they've been bleached by long-term, unshielded UV exposure (in a near-vacuum)."
] | [
"Not necessarily. The American flags placed on the Moon by the Apollo missions are, by this point, unidentifiable as such as they've been bleached by long-term, unshielded UV exposure (in a near-vacuum)."
] | [
"Not necessarily. The American flags placed on the Moon by the Apollo missions are, by this point, unidentifiable as such as they've been bleached by long-term, unshielded UV exposure (in a near-vacuum)."
] |
[
"Can someone explain a strange thing I noticed today? Water bottles and sound vibrations..."
] | [
false
] | So today while I was in class listening to the teacher I was drinking from a water bottle. Not special, just a regular plastic bottle with water. And I noticed that every time my teacher spoke, I could feel the sound vibrations in the water bottle. To make sure it wasn't just me, I handed it to a friend and sure enough... | [
"An object or cavity will resonate at certain frequencies. The frequencies it resonates at are dependent on the size of the object, since frequency is related to wavelength, and it resonates when a given wavelength fits neatly into the object/cavity. This is the basic principle behind musical instruments; you chang... | [
"Yeah, you'll measure a lower magnitude in the driven resonance if the driver is a bit further off the resonant frequency.",
"As for why different parts of the bottle vibrate more or less - it depends how exactly the vibrational mode you're feeling fits into the bottle. Since these are standing waves, there will ... | [
"huh. thanks. but I could feel it when I talked too, just not as much. Does that mean my voice was just a little more off. And I also noticed that holding different parts of the bottle increased or decreased the vibration. further explanation?"
] |
[
"In information theory, if I = log 1/p, then an impossible or extremely unlikely event would have infinite information, can this explain the origin of the universe?"
] | [
false
] | [deleted] | [
"Let's address your questions in turn.",
"Would that mean that an impossible or extremely unlikely event would have infinite information?",
"Correct. To be a bit pedantic, it would mean an impossible event has infinite ",
". This measure is often called ",
", for obvious reasons: the event ",
"1 equals 2"... | [
"I think it is also worth noting that the term \"information\" in this context is quite specific, and often doesn't make sense out side of some explicit statistical procedure (with some sort of ",
"prior distribution",
").",
"It is very easy to have infinite information and still not know something specific. ... | [
"Usually it is best to avoid thinking of the information of a single event. Entropy, as defined from axioms, is over a set of events, and thus so is mutual information. Only in specialized instances is self information useful in information theory. ",
"The reason for that is information, conceptually, is supposed... |
[
"If you had a set of points but instead of having their coordinates you just have arbitrary values of distance between each of them, how many dimensions would you need in order to map them?"
] | [
false
] | null | [
"So if you have ",
" points and the distances between each of those, and assuming those distances obey the triangle inequality (the distance from A to B can never be longer than the sum of distances from A to C and from C to B), then what you have is a discrete, finite metric space.",
"Such a metric space can a... | [
"The triangle inequality isn't sufficient, right?",
"Consider AB=BC=CA=2, AD=BD=CD=1. No single triangle inequality is violated but you can't put D on every side of the equilateral triangle A,B,C at the same time.",
"Edit: Typo in the equation",
"You can find a space with a different metric, of course, but no... | [
"Yeah, you're right. The metric space must also be Euclidean. ",
"Edit: I quoted this theorem inaccurately. No longer sure what the correct version is."
] |
[
"How do we know how ancient civilizations music looked like ?"
] | [
false
] | Hello ! I am currently listening "wiking-sounding" music like Wardruna, and I was wondering, we discovered instruments used by ancient civilizations, but how do we know how they used them, and how they sang ? (Thanks for your future responses and sorry for bad english) | [
"The study of ancient music has been going on for sometime, and is considered a multi-disciplinary field of research.",
"Generally it falls into several different categories:",
"Now, that said, any reconstructionist approach is never going to be truly accurate.",
"For many cultures, we don't know how fast son... | [
"As far as Wardruna is concerned, I absolutely agree with you, but it should be noted that probably a differentiation has to be made. I mean, look at the Skald album for example. Not as popular as the others but probably more accurate."
] | [
"Thanks for mentioning the Skald album. I'll give it a listen!"
] |
[
"What happens when an Anti-Atom meets a normal atom?"
] | [
false
] | [deleted] | [
"Well it really means what you mean by \"meets.\" But usually one means in the sense of slow moving collision. So as they approach each other, the electron in one and the positron in the other annihilate to produce two gamma ray photons with total energy equal to twice the electron mass (since you had two electron-... | [
"the picture... and note, this is just a ",
", it may not be the ",
"... is that in one instant, the electron and positron simply... cease to be. And two new photons are created at that same instant."
] | [
"I'm not sure if this is something you could answer, but how can we visualize the meeting of anti-particle and a normal particle? Is it just that they would meet and then merely disappear? Annihilate is obviously a strong (but accurate) word with connotations of explosions - is it an extremely rapid process?"
] |
[
"Do deafblind people (like Helen Keller) suffer from diminished/lower/deteriorating cognitive and memory abilities due to sensory deprivation and lack of stimulation?"
] | [
false
] | Granted, deafblind people are not completely deprived of all senses (still have smell, taste, feel), but they lack arguably the two most important senses, sight and hearing. There have been studies on . For example, one study had their subjects merely stay in a pitch black and soundproof room for . The study showed t... | [
"I wonder if people would show the same response if they lacked hearing and sound but were placed outside on a sunny day, or in an ordinary room with objects to interact with.",
"After all, these rooms are not only depriving them of sound and sight, but also any objects to interact with, any feeling other than th... | [
"The answer to your question depends entirely on what caused someone to become deaf/blind, as many of the causes can easily also lead one to become MR, but in general, there isn't any reason to think that they have diminished cognitive skills at all. Some examples include a significant blow to the head, lack of ox... | [
"For the most part, if only the sensory systems are affected (e.g. a born-deaf child has cateracts), then cognitive abilities are retained, especially if appropriate education is given. In nearly every case of deaf-blind studied, non-sensory system activity largely is similar to sighted/hearing individuals, for ex... |
[
"What causes a 'Flu Season?' Why isn't it a year long disease?"
] | [
false
] | What is it about the August-December months that causes the Flu to be a rampant disease? Also, a follow up question, are the opposite months (April-July) considered the Flu season for the Southern Hemisphere? | [
"Also, a follow up question, are the opposite months (April-July) considered the Flu season for the Southern Hemisphere?",
"Google trends is good for a question like this. This ",
"link",
" shows that in the year 2007 Australians mostly searched for flu in August, which is their winter. Not every year follows... | [
"I'd appreciate if you have the source for this.",
"Wow! ",
"Found it myself but thanks for the impetus =p",
"Our bodies limit blood flow (including white blood cells) to cold extremities. If I may expand his theory, our nasal mucosa are actually the first barrier to incoming flu droplets. And if we limit blo... | [
"In 2009 it was a year-long disease. This was the pandemic H1N1 that was tearing around the world causing unusual mortality in infants. Something similar happened with the Spanish flu pandemic of 1918, and less so a handful of years after. No one truly knows why flu is ",
" seasonal though, but I have one ",
... |
[
"Thermodynamics / does water heat faster if it enters at the top or bottom?"
] | [
false
] | So I'm laying awake and wondering about a stupid problem, Let's say you make a coil of copper piping, spiraling upwards Now you add a fire to the bottom of this spiral, a pile of coals at the bottom, and flames reaching the top If you run room temperature water through this pipe, Would you see a difference in temperatu... | [
"good question, the answer is top to bottom. This is called countercurrent flow and it is more efficient because a larger temperature gradient is maintained throughout the process.",
"by temperature gradient I mean the difference in temperature between the copper and the hot air around it. The heat transferred is... | [
"My little giant hot water heater is a metal box, propane heat and copper coils as described yet it feeds cold water from below. Why would that be?"
] | [
"does the water come out the top or bottom?"
] |
[
"Why do we forget most of our dreams, and why cant we remember what they were about after some time?"
] | [
false
] | [deleted] | [
"I'll direct you to this ",
"2004 review article",
" which discusses sleep and memory consolidation. Particularly, check out the section titled \"Sleep Is an Amnesiac State.\" The author highlights a series of functional imaging experiments from the late 1990's. During REM sleep, brain regions which can be t... | [
"There's some studies on remembering dreams that point to the shift from bi-phasic to mono-phasic sleep cycles has a profound impact on dream recall. It's not just about trying to remember or not."
] | [
"There's some studies on remembering dreams that point to the shift from bi-phasic to mono-phasic sleep cycles has a profound impact on dream recall. It's not just about trying to remember or not."
] |
[
"What exactly makes a substance carcinogenic?"
] | [
false
] | null | [
"It boils down to a substances ability to damage or disrupt DNA, or it's ability to affect other cellular processes. Carcinogens are subcategorized into Genotoxic (those that affect the genome) and Nongenotoxic (those that affect other parts of the cell). ",
"There are many mechanisms by which a substance can dam... | [
"Carcinogens are mutagens that activate uncontrolled cell growth (cancer) by over expression of proto-oncogenes or under expression of tumor supressor genes."
] | [
"If it can cause cells to mutate. Basically, a carcinogen is anything that can cause mistakes in cell mitosis, because the mistakes can become cancerous cells.",
"There isn’t a specific chemical or particle that makes something a carcinogen."
] |
[
"What causes the Earth to spin on its axis?"
] | [
false
] | null | [
"Conservation of angular momentum. The Earth has a kinetic rotational energy it obtained during its formation and outside interacting tidally with the Moon and other celestial bodies doesn't have a way to get more or get rid of it.",
"So nothing continuously causes it, no force is require to keep it spinning."
] | [
"To keep it simple, collisions between objects during the formation of the solar system caused the spinning."
] | [
"To keep it simple, collisions between objects during the formation of the solar system caused the spinning."
] |
[
"How was Avogadro's number chosen?"
] | [
false
] | We all know that there are 6.022x10 molecules in one mole of a substance, but how was that number selected? As moles is just a unit of measurement, it had to have been specifically chosen for some reason or another. | [
"Avogadro's number was chosen such that a mole of carbon-12 weighs exactly 12 grams. There is currently work being done in order to give it a more rigorous definition though. ",
"NIST.gov",
" has a description of that project which will not only help define Avogadro's number but the kilogram as well."
] | [
"technicality:",
"it has 12 grams of mass. weight has nothing to do with it."
] | [
"Which is ",
" to the point made by OP about Avogadro's number. Because, if you put a 12-gram mass on a balance, whether on Earth or Mars or wherever else, you will need another 12-gram mass to even the scales. Which is the same as saying that something \"weighs\" 12 grams. If you're teaching science to middle sc... |
[
"Would a black hole just look like a (fading, redshifting) collapsing star frozen in time?"
] | [
false
] | I've always heard that due to the extremely warped space-time at a black hole's event horizon, an observer will never see something go beyond the horizon and disappear, but will see objects slow down exponentially (and redshift) as they get closer to the horizon. Does this mean that if we were able to look at a black h... | [
"This",
" black hole from interstellar was said to be the most realistic rendering of a black hole to date. You can see the accretion disk caused by the black holes massive gravitational field. An accretion disk is formed by diffuse materials orbiting a large central mass.",
"Inside the orbit of the accretion d... | [
"The Interstellar pic you linked actually isn't the most realistic rendering. ",
"The render in the movie is actually a dumbed down version.",
" Nolan veto'd it because he thought its asymmetry would confuse viewers and because it wasn't as asetically pleasing.",
"Also, the accretion disk isn't light in orbit... | [
"Does this mean that if we were able to look at a black hole, we would see the matter that was collapsing at the moment it became a black hole?",
"No, you don't see objects; you only see their photons that enter your eye. As a body falls into a black hole, there is some last photon that escapes before the body cr... |
[
"If an ant fell from the top of the Empire State Building, would the fall injure or kill it?"
] | [
false
] | the comments have changed everything. Forget Ants, we need to know if a cat would survive that fall. | [
"No, because an ant's terminal velocity is too small do it any harm when it lands. In fact it will probably be moving faster from any latent wind or air currents than from its falling speed.",
"This 1928 essay might be illuminating: ",
"http://irl.cs.ucla.edu/papers/right-size.html",
"ugh fucking reddit 503 e... | [
"Are you telling me that ants are immune to fall damage? That is pretty awesome."
] | [
"On Earth, yes. But in a vacuum...",
"\"We choose to go to the Moon! Not because it is easy, but because we are bored.\""
] |
[
"If its true what Aubrey de Grey says, why isnt anti- biological aging funded more aggressively"
] | [
false
] | null | [
"This is right up my alley, as I've done (primary/published) research in bacterial DNA damage and repair, cancer genomics, and cardiovascular disease. I'll ",
" to keep this brief. Also, I cannot read his work thoroughly because of time, so I have to keep my responses limited to his TED talk",
"First, we have t... | [
"This is Dr. de Grey. It's hard to avoid a tl;dr reply here, but I'll try. The public, and hence funding sources, view \"aging\" as distinct from diseases, and \"curing aging\" as either theoretically impossible (like perpetual motion) or else focused on extending life rather than preventing disease. Both are nonse... | [
"This seems relevant, from his wikipedia page:",
"The \"pro-aging trance\" is a term coined by Grey to describe \"the impulsion to leap to embarrassingly unjustified conclusions in order to put the horror of aging out of one’s mind\".[15] According to de Grey, the pro-aging trance or \"pro-aging edifice\"[16] is ... |
[
"If a fungus feeds on radiation, doesn't that make it a plant?"
] | [
false
] | My questions is in reference to I'm wondering, if a fungus feeds off radiation, how is it any different from a plant, then? Plants feed off light, which is a type of radiation. Or do they technically not "feed" off of it, more just use it as a catalyst for the chemical reaction of photosynthesis? | [
"It does not make it a plant. Something is only a plant if it evolved from plant ancestors.",
"However, if they're statement about using melanin as a chlorophyll analogue is correct, it would suggest some autotrophic features of the fungus, which is really neat. ",
"I guess it would be (kinda) a plant-like fung... | [
"To put it another way, \"feeding on light\" is a characteristic that \nplants share, not \"the definition\" of a plant. It would be misleading\nto consider \"Birds fly\" to be false, yet there are other things that\nfly, and birds that don't fly.",
"Definitions are secondary; primary are regularities in the wor... | [
"List of myco-heterotrophic genera"
] |
[
"How do scientists determine how far away a star is?"
] | [
false
] | I know it has something to do with the red-shift or blue shift, but I never could understand it fully. Can someone help me please? :] | [
"Well there are a couple of ways. ",
"The nearer stars we use a method called ",
"parallax",
". It's geometry, so we can be pretty confident on those values. ",
"Then, analyzing parallax measurements we found that some stars had a specific brightness. We call these the \"standard candles;\" the dominant typ... | [
"Well each measurement builds off of the overlap with previous measurements. But the most distant galaxies are too distant to resolve the Standard Candles (like supernovae) so the only thing we can go on is the red shift.",
"But the point is that parallax and Cepheid variables have a range where you can perform b... | [
"Well each measurement builds off of the overlap with previous measurements. But the most distant galaxies are too distant to resolve the Standard Candles (like supernovae) so the only thing we can go on is the red shift.",
"But the point is that parallax and Cepheid variables have a range where you can perform b... |
[
"When I look at the sky, I can't tell the difference between a planet and a star. How did people in ancient times figure it out?"
] | [
false
] | null | [
"Planets and Stars have very different motions in the sky. The word \"planet\" literally means \"Wandering Star\" due to the retrograde motion they display. "
] | [
"Planets move relative to the constellations, whereas the stars don't."
] | [
"Also the twinkle. Stars twinkle because they're so distant that they're effectively single points on the sky. While planets have smaller radii than stars, they're ",
" much closer to us that we can actually see them as discs with spatial extent on the sky, so their light can come through the atmosphere without b... |
[
"Can humans survive without any bacteria in/on their bodies?"
] | [
false
] | I'm thinking about digestion and such. Any short term and long term consequences to this? | [
"As babies are being born they actually obtain a significant amount of initial flora from their passage through the vaginal canal, beginning the cultivation of the normal flora they grow into throughout their development."
] | [
"Newborns are essentially sterile and are decidedly alive, though they pick up and start cultivating microflora pretty much instantly. There are cases where lack of gut flora cause digestion issues, as commonly seen during antibiotic regimens, and chronic cases are possible (fecal transplants can treat this). Most ... | [
"We have become so dependent on our micro animals that we couldn't survive without them. The scientists have even discovered direct link between obecity and the type of bacteria that live inside out gi tract. That is how important they are for our digestion. Even on the outside there are types of bacteria that live... |
[
"Some redditor posted something about \"dry water\" a few days ago, I wanted to see if anybody knows anything more about this."
] | [
false
] | I have done a little reading on the subject, but not much more than what can be found at Wikipedia: I am mostly interested in how this could be used to reduce greenhouse gases in the atmosphere, but would love any knowledge or opinion on the subject. | [
"I'm currently doing active research on Carbon Capture technology, and this isn't even in the pool of realistic ideas. The solubility of carbon dioxide in water is so low that triple it is still way too low. (1.45 g/L at 25 °C) ",
"wiki",
" ",
"The capture rate would be exceedingly low as well, and as other... | [
"No opinion or knowledge sorry. I just remember seeing it on Cracked. They have some links in the article but they aren't much better. Maybe try searching for papers by the scientist?\n",
"http://www.cracked.com/article_19088_6-brilliant-inventions-that-look-like-gag-gifts.html"
] | [
"Here are some links for you.",
"It is not just water...",
"Cooper Group",
"Cooper Group News q.v. April",
"Andrew Cooper",
"Ben Carter",
"Daily Telegraph article"
] |
[
"Given the tremendous cost of their design and launch, and the relatively low cost of their operation, why aren't more NASA missions designed to operate longer?"
] | [
false
] | I'm referring generally, but this question was triggered by the Mars Science Laboratory (Curiosity) which is designed to operate for just one Martian year (~2 Earth years). Now, the track record of the rovers has been very good, but it strikes me as odd that we'd spend over $2 billion to operate a machine for just a f... | [
"Why don't we put any probes into a highly elliptical, precessing, solar orbit so that they can periodically recharge by approaching the sun, and then make orbital trips to planets?",
"The trajectory of a deep space probe is something like a fantastic Rube-Goldberg machine or a pool shark's trickiest shot. They h... | [
"Thanks for your response. ",
"The trajectory of a deep space probe is something like a fantastic Rube-Goldberg machine or a pool shark's trickiest shot. They have almost no engine thrust and so they rely on tricks using very precisely timed launches to bounce between planets on their way out.",
"Is this to sa... | [
"I can't speak for NASA personally, but in the aerospace industry we build quite a lot of conservatism into our analyses. When we say that something will work for 2 years, that generally means that it will work for no less than two years. It's not like a consumer product where it's \"it will probably work for two y... |
[
"What would happen if the Higgs field started to shut down and then it turned off?"
] | [
false
] | null | [
"There is no \"turned off\" It simply is. That's like asking what would happen if the ocean turned off."
] | [
"They can also freeze, flow, and several other things that have no relation to \"turning off\"."
] | [
"While the Higgs field can't just \"shut down and turn off,\" something akin to what you are imagining did happen in the early universe.",
"The Higgs field has always existed, but what has changed is the default value of the Higgs field present throughout space. In the very early universe, the value of the Higgs... |
[
"Is it possible that the universe is the \"surface\" of a four-dimensional hypersphere?"
] | [
false
] | This is pure speculation of course. I was just thinking this earlier today. It would explain how the universe could have no edge but still be finite. Just like how a two-dimensional world (like Flatland) would seem like an infinitely expanding plain to observers if sufficiently large, but could really be the surface of... | [
"We've considered this, but we've tried to measure the curvature of the large scale universe, and found it to be remarkably flat. The smallest possible \"sphere\" it could occupy has a \"surface\" (volume) with no less than 251 times our observable universe within it. More realistically though, we just think the un... | [
"What we really mean though is that in a flat space, triangles have 180o in their interior angles, and the ratio of a circle's circumference to its diameter is pi, and two parallel lines never converge. In positive space, triangles have less than 180o , a circle is less than pi, and parallel lines converge twice. ... | [
"A 'simple' way to describe it is in terms of the three available geometries for the universe, open, flat, and closed. An open universe expands forever (i.e. Big Rip). A closed universe will collapse in on itself (Big Crunch). A flat universe expands forever...but just barely. ",
"In a flat universe, triangles ha... |
[
"If a redwood or pine tree were to live in the perfect conditions, with enough nutrients and without pests or disease or deforestation. Could the tree live forever?"
] | [
false
] | null | [
"Keep in mind that all tree stems eventually die; trees MUST grow to survive, so a tree will inevitably grow itself into a precarious situation, either outstripping its nutrient or water supplies, or growing to big to support its size. The longest living single stem trees are bristlecone pines, which another poster... | [
"Survival results in growth. ",
"The cambium (the part of the tree that makes new cells) produces a network of wood on the inner part of the tree which allows nutrients to move up and down the tree. It also produces a new layer of bark to defend itself. ",
"When a tree gets to a certain height, it cannot get th... | [
"Can you please explain \"trees must grow to survive\" part? Surviving results in growth, or growth is a tool for surviving?"
] |
[
"Theoretically, would a paradoxical statement actually cause a robot, or other AI entity, to die/freeze up/malfunction?"
] | [
false
] | null | [
"Short answer: nope.",
"You can program paradoxes all day long, and it wont hurt a thing. Students in cs 101 do this all the time (though not on purpose )"
] | [
"What they call \"AI\" is often search. Consider, for example, computer chess: the machine is considering millions of possible sequences of moves. Or, consider neural network training: the machine is trying millions of neuron configurations to find a configuration that produces the desired output. Or, in plannin... | [
"Not necessarily, however it could hamper performance. an infinite loop could use up resources and eventually cause system errors."
] |
[
"What would happen if the moon disappeared?"
] | [
false
] | null | [
"The light of the moon is very important for nocturnal species. ",
"Owl monkeys",
", for example, don't move around much when the moon isn't out. The lunar cycle also serves to ",
"synchronize mating",
" in many species. It's unclear how well these organisms (or any animal which uses the moon for navigation... | [
"Much (if not most) of the internal mixing within the ocean is driven by the tides. Reducing the mixing rate would alter the ocean's stratification and the large-scale thermohaline circulation. Reduced mixing would also lower the supply of nutrients to the surface ocean and probably lead to an overall lower biolo... | [
"Tides would mostly be gone, the Sun causes a smaller tidal effect so that would still be there. There are probably a whole lot of hydrologic and atmospheric stuff that are affected by tides so as a consequence of tides disappearing there could be pretty far reaching effects. Not really my expertise so don't know w... |
[
"Why don't human eyes track smoothly and instead jerk around when they move?"
] | [
false
] | I've noticed that, for instance, cat eyes move smoothly when they are looking around. But human eyes jerk around from one thing to another when viewing their surroundings. Why is that? Also, I've noticed that human eyes are actually able to move smoothly if they are focused on a single object and the head is rotated, b... | [
"Searched",
"Relevant ",
"discussion",
"Original question by ",
"Cars are going past on the road outside the coffee shop here, and I can follow them as they pass in one smooth motion, left-to-right or whatever.",
"However, if I try and run my eyes along the edge of the pavement, or the road lines, they ju... | [
"Does blinking or closing the eyes not \"reset\"?"
] | [
"they do track smoothly, as long as you are tracking something. They don't when you just want to look around."
] |
[
"What was the population density of T Rexes?"
] | [
false
] | A question I've always had about them - surely as gigantic apex predators, they would have required a large hunting area to feed themselves, but they also have to be densely populated enough to find other T Rexes and reproduce. Do we know how many T Rexes would have existed across North America, for instance? | [
"I'm not sure that African elephants serve as a great comparision to T-Rex. Elephants are herbivors so you'd think you could support a lot more of them in comparision. ",
"I suppose its kind of cancelled out by the fact that elephants are warm blooded mammals though."
] | [
"thats a hard question... you can't use the fossil record to predict this because fossils are so rare, and any data you gathered from dig sites would become complete uneducated guesses.",
"",
"So... if we will compare them to the distribution of the largest land animals today. African elephants numbered 3-5 mi... | [
"I was thinking the same when writing this. The carnivores are way less populated and more spead to not encroach on each other's hunting grounds.i was thinking of using American Alligators."
] |
[
"Do primates get under arm body odor as humans do?"
] | [
false
] | null | [
"An interesting side note to that is that not even all humans get it. There's a very strong genetic influence on whether or not your sweat generates BO. People in the Far East are far more common than Western countries to have the gene which means they don't get BO. It's one of the reasons finding deoderant in the ... | [
"It is, but 80 and 90 percent of people with Asian and native American ancestry respectively lack the genes to create food for the bacteria that creates body odor. This often comes with dry flaky ear wax."
] | [
"There must be an interesting paper done on this and it's relationship to individualism of the west and strong interdependency of the east. "
] |
[
"Why does the polarity of the Sun reverse every 11 years?"
] | [
false
] | I was reading from the WSJ. It mentions that the sun has an 11-year cycle and that the poles normally reverse each cycle. How is that possible and why? | [
"In heliophysics it's still a mystery as to exactly why. Based on models, and scientific charts, it can certainly be deduced something is happening. Fortunately the magnetic tendencies of our star are being heavily researched:",
"http://sdo.gsfc.nasa.gov/",
"Some sources:",
"http://solarscience.msfc.nasa.gov/... | [
"The oscillation is a property of multi-reservoir dynamo systems. I'll explain at the bottom.",
"Nobody knows why it's 11 years (more or less) and not, say, 15 or 5. The fundamental process is probably the \"Alpha-Omega\" dynamo, which relates to two angular rotation parameters. In very brief: the outer layer... | [
"Hate to tell you, but the ",
"earth does it too",
". On average once every half million years. ",
"Here's a ",
"pic",
" to scare the hell out of you."
] |
[
"Why does male pattern baldness typically begin at the top of the head?"
] | [
false
] | null | [
"Not sure that is consistently true at all. High testosterone levels also leads to a large amount of body hair in males, a trait which most women I have spoken to about it find deeply unattractive. Indeed, I've seen it theorised that humans lost their body hair (mostly) because of sexual selection against it. Ano... | [
"Not sure that is consistently true at all. High testosterone levels also leads to a large amount of body hair in males, a trait which most women I have spoken to about it find deeply unattractive. Indeed, I've seen it theorised that humans lost their body hair (mostly) because of sexual selection against it. Ano... | [
"Haha, as a balding man i want to believe this, so i will—thanks for the confidence boost!"
] |
[
"Can a surface that appears matte in visible light act like a mirror in other (longer) wavelengths?"
] | [
false
] | I seem to recall my heat & mass transfer professor explain that a surface that appeared dull in visible light could act like a mirror to infrared radiation. He demonstrated this by using a sheet of metal and an infrared camera to show his "reflection" that was actually pretty similar in appearance as if he had the came... | [
"Of course. Simple example is a radar antenna. It's typically a parabolic section, made of wire. The holes in it don't matter, as they are smaller than the wavelength being monitored. Same thing for a microwave door.",
"The point is, any detail shorter than a particular fraction of a wavelength isn't picked up at... | [
"And why too? Why would something turn into a mirror at a certain wavelength (infrared), but normally be a solid, non reflective object in visible light? You'd think it would be more \"see through-able\" as you shifted up (or down) the spectrum."
] | [
"I guess I would say that, in the case of a reflective metal surface mirror, that if it were perfectly polished, that it'd reflect all light pretty well. As it got more rough, it would only act as a mirror to certain wavelengths, and it would distort/scatter light to others. ",
"If it were a glass mirror with a ... |
[
"Do bugs feel the same amount of pain we feel when we lose a limb?"
] | [
false
] | [deleted] | [
"We can't tell what a bug feels but by any real measure bugs don't feel pain anything remotely like higher organisms. There Are tons of videos of bugs continuing to eat while being eaten alive, moving around trying to eat while missing their heads, there's a beetle that's missing all of its internal organs but sti... | [
"No. Pain and nocioception are not the same phenomenon. ",
"Nocioception is the ability to detect noxious stimuli - for example, excess heat. This can elicit a response that all but bypasses the central nervous system. This is why you can touch a hot object and jerk your hand away before you even realize it w... | [
"Instinct. The same reason a fly flies when you swing your hand at it. ",
"I have a similar memory of throwing crickets into a spider web that I don't like. Despite them not feeling pain they are still alive and I don't think people should go out of their way to torture them."
] |
[
"Question about time dilation and the \"Twin Paradox\""
] | [
false
] | I'm trying to understand how time dilation works and I found a pretty thorough explanation on Special Relativity that covers time dilation, Doppler Shift, and the Twin Paradox from HowStuffWorks. Here's the snippet I'm confused about: "Let's take another trip with the twins, but this time John will travel 12 hours away... | [
"Yeah, I figured. Thanks for your replies though I definitely understand it a bit better now."
] | [
"Yeah, I figured. Thanks for your replies though I definitely understand it a bit better now."
] | [
"The term \"speed of light\" is a relic from the past where light was measured to move at c. There's nothing special a light aside from the photon being massless, any massless particle(graviton, for example) will move at c. The part that differs from classical physics is that c is always the same value regardless... |
[
"If we had a telescope strong enough to see the surface of a planet 5 lightyears away, would the events be taking place clearly in real-time, effectively looking at the past?"
] | [
false
] | If so, we should put a giant mirror in space that faces us so we can look at it and view our past. | [
"never worry about sounding dumb in order to learn "
] | [
"never worry about sounding dumb in order to learn "
] | [
"You are correct. If we had a telescope strong enough we would be \"looking into the past\" of another planet.",
"Regarding your mirror idea, if we placed the mirror 5 light years away, flying at the speed of light we would be able to put the mirror up in 5 years, and have to wait another 5 years for the light to... |
[
"Do all Covid variants have the same incubation period, and does such an incubation period mean less selective pressure toward a less deadly mutation?"
] | [
false
] | It’s my understanding that the key issue with covid is the pre-symptomatic incubation period where it can still spread from person to person, which can last about two weeks. Have there been any variants that don’t have such an incubation period? And does the pre-symptomatic spread mean that a deadlier and more infectio... | [
"We don't know that yet for sure. Delta ",
" incubate faster than the other variants, but this is yet to be proven. As far as I'm aware Delta is the only variant suspected to incubate faster.",
"There is no variant with no incubation period at all."
] | [
"Some suspect that Omicron might incubate faster."
] | [
"Incubation periods can change with variants. But are unlikely to change drastically. ",
"In terms of which variant becomes the predominant variant. That’s based upon how infectious it is (it’s r number). How deadly a virus is doesn’t have any real bearing on wether it becomes the predominant variant. If anything... |
[
"Artist asks scientists; How can I make a large rigid panel for an unforgiving medium?"
] | [
false
] | [deleted] | [
"/r/AskEngineers",
" might be helpful."
] | [
"This could be a structural engineering problem more than a materials problem. I learned how to make lightweight rigid panels for my artwork after day-jobbing making architectural models. Imagine your surface is the floor of a house. What keeps a floor from sagging or drooping under the weight of furniture and p... | [
"Sorry, can you explain, in as excruciating detail as possible, what the standard panels you use with these paints are made of? I'm guessing not canvas stretched over wood. Can you also describe the failure mode of the panel larger than 24x36 that you tried? Did it peel off the panel, or did the panel just bend? wh... |
[
"Is a Hurricane just a giant tornado?"
] | [
false
] | null | [
"No. The simplest way to put it is that hurricanes and tropical systems drive themselves by creating heat which increases wind. This requires large areas of water to occur. Tornadoes happen over plains and require a a wedge of cold and warm air to create spiraling motion, which eventually reaches the ground. ",
"... | [
"No. They're both storms rotating around low pressure systems, but the forces that make them spin are totally different. The two relevant forces that can produce spin from a low pressure area are the coriolis force and centrifugal force; in both cases, the speed of the rotation increases until this force balances... | [
"not quite... i'm sure it was just a typo but i'll chime in anyways.",
"although hurricanes in and of themselves do not create heat, they are driven by heat though. a hurricane is basically a giant conglomerate of thunderstorms that are rotating in a low pressure system. in just the same way that thunderstorms ar... |
[
"What is physically happening in the brain when we forget something?"
] | [
false
] | null | [
"Many times it is the result of either inefficient encoding, or an insufficiently salient cue for retrieval. Memory traces do degrade with time, but sometimes a memory can be retrieved by using a different cue.",
"Also, while long-term potentiation seems to be necessary for memory, there is not consensus yet on w... | [
"This is generally the consensus at this point in research. You’ve summed it up nicely - insufficient cues, insufficient coding, or potentially actual changes in the network itself. At one point, it was considered that forgetting was the result of “writing over” a memory, essentially, like a computer writes over da... | [
"In my physio-psych classes they made a big del about the fact that writing something down is one of the best ways to get it in to long term memory and have it able to be recalled quickly. It activates networks in the visual, language, speaking, and motor sections of the brain. This was 200 level stuff so I don't... |
[
"A balanced diet - Ramen and Vitamins?"
] | [
false
] | I was chatting with my room mate who was complaining that I eat too much and it's too expensive to get food. I have always eaten a lot so I told him to just buy a bunch of ramen noodle packets next time he goes for food because they are inexpensive. I know that this leads to serious nutritional imbalances if eaten alon... | [
"Ramen is harmful in high amounts because of the high amounts of sodium and saturated fat. Take a look at the nutrition label; just two packets will completely cover your sodium and saturated fat requirements for the day. And are you really going to survive on just two ramen packets a day?",
"Add to that the fact... | [
"It should also be added that vitamin pills alone aren't going to do the trick. It's right there on the label, too - they're called \"supplements\", not \"replacements\".",
"Your body can't store a lot of vitamins and just excretes whatever it can't use. A pill might contain 100% of your daily dose of vitamin C... | [
"No, its definitely not a balanced diet. You have to put a lot of vegetables and maybe even some meat in ramen to make it somewhat healthier. Also you only need like half the seasoning packet, or maybe none of it at all. You can just add low sodium soy sauce, mirin wine, sesame oil, garlic, ginger, onions, maybe... |
[
"Can a bioengineered rubisco enzyme with improved enzyme kinetics be a potential solution in helping to mitigate carbon overproduction, climate change, and help with food yields?"
] | [
false
] | I am not a plant physiologist or a biochemist, but I do know a little bit about biology. I understand that rubisco is an enzyme found in plant chloroplasts that catalyzes the incorporation of atmospheric CO2 into ribulose-1,5-bisphosphate (RuBP). RuBP can then enter the rest of the Calvin cycle reactions. I’ve learned ... | [
"I’ve learned that rubisco has one of the slowest enzyme kinetic profiles, and considering that this enzyme facilitates atmospheric CO2 incorporation into organic molecules, wouldn’t it be important, in terms of climate change and food yields, to genetically engineer an enzyme with faster kinetics?",
"It seems li... | [
"Additionally, Rubisco has been around for a very long time evolving separately in many different organisms. There is ",
"a lot of variability",
" in enzyme kinetics across different organisms and some tradeoffs that are associated with increased carboxylation. ",
"C4 photosynthesis comes with a lot of downsi... | [
"Well geneticists got a 40% increase in growth after 2 genes one from algae and one from pumpkins where added to tabaco plant for a more efficient photo respiration pathway. (they also deleted a gene to make sure the C2 product stayed in the chlorophyll and was recycled there.)",
"https://science.sciencemag.org/c... |
[
"I was reading a book about Albert Einstein when I got to the e=mc2 part. Reddit Scientists, I have a question."
] | [
false
] | null | [
"I understand your position, but that still doesn't answer my question of 'why the speed of light, as opposed to just an arbitrary number?'"
] | [
"I understand your position, but that still doesn't answer my question of 'why the speed of light, as opposed to just an arbitrary number?'"
] | [
"This video explains it",
". It was a proof that followed directly from other, known laws of physics."
] |
[
"How does the human digestive system separate solids from liquids?"
] | [
false
] | [deleted] | [
"They all mix together into a liquid solution. This is broken up in the stomach and nutrients are absorbed through the small intestine (enzymes in the stomach and small intestine help with this). In the large intestine components that cannot be absorbed (e.g. cellulose) remain and the water is re-absorbed, leaving ... | [
"If you're asking how urine and faeces are produced separately, it's because the solids follow a single path (in the mouth, out the anus). Although there's a few intermediate stages, there's a single tube from one end to the other. In the case of urine, fluids are absorbed into the bodily tissues then waste is extr... | [
"The mouth is the entrance to the human digestive system. Teeth gnash the food, breaking it down mechanically, while the three salivary glands release saliva containing the enzyme amylase, which breaks down starch and fat chemically. Saliva makes food easier to swallow by moistening it, as well as preventing the er... |
[
"Is it really possible to colonize other planets considering the laws of special/general relativity?"
] | [
false
] | When I was in high school I read Brian Greene's "The Elegant Universe" and I remember it crushing my dreams of an intergalactic future. Specifically, even if we could somehow create spaceships that flew fast enough to move between solar systems or galaxies, the time paradox (or whatever) would mean that by the time I l... | [
"wormholes are outright unphysical. They're cute mathematical abstractions, but the mass-energy that is required to create such a space-time curvature is unphysical. "
] | [
"As long as you don't care about communicating with the people back on Earth, this doesn't pose a problem."
] | [
"It's not as crazy as you imagine. The entirety of human civilization is a small place today, it takes mere hours (or sometimes minutes) to travel to the other side of the planet, and it takes mere milliseconds for messages to travel around the world. But it wasn't always that way. For much of human history it took... |
[
"How does half life work?"
] | [
false
] | What isn’t whole life stated instead of half life? | [
"The \"whole life\" is incredibly long, and depends a lot on random chance.",
"Basically, every nucleus has a 50/50 chance of decaying every \"half-life\". So if you have a billion nuclei, about half of them will decay over one half-life. You now have about half a billion undecayed nuclei. Each of those nuclei st... | [
"Everything you wrote is correct, but you mixed up the central limit theorem and the law of large numbers. ",
"The central limit theorem says the distribution of the addition of a bunch of distributions will approach Gaussian (regardless of the individual distributions). ",
"The law of large numbers says the me... | [
"It sounds like you're misunderstanding what half-life even is. It's not half the lifetime of a thing, it's the lifetime of half of the thing.",
"Every half-life, you can expect half of the thing to go away. And then, after another half-life, half of _that_ will go away, leaving one-quarter of the original. After... |
[
"Exactly what is radiation?"
] | [
false
] | Can someone explain this to me like I'm an idiot? I've been through science, but I was never able to total grasp just what radiation is. Is it a...thing? A...condition? Can I hold "a radiation" in my hand? Also, what does it do to the human body that's so bad? What is the actual mechanism of damage? Does it burn ... | [
"Basically, it means knocking electrons loose. Atoms bind into molecules through the \"sharing\" of electrons. If enough electrons are knocked free, it can break the connection between atoms and molecules, leading to damage to important chemicals in the body. Most importantly, this kind of damage to DNA can cause s... | [
"Is it a...thing? A...condition? Can I hold \"a radiation\" in my hand?",
"These are very good questions. I'm not an expert in the biological aspects, but I'm sure someone around here is. I'll just describe what radiation is. There are three types: (",
" 3 ",
" types, see kahirsch's comment below)",
"If you... | [
"What does \"ionize random atoms\" mean? (sorry)"
] |
[
"After infection, does constant exposure to virus maintain a higher antibody level?"
] | [
false
] | [deleted] | [
"With all due respect these idiots should be fired.",
"Even if they already HAD covid, they can still SPREAD it to others. And they WILL because they get in contact with the virus on a daily level.",
"Worst case: they infect a previously uninfected person who they are testing. That person then receives a negati... | [
"Well, reexposure to the antigen will trigger the proliferation of memory cells and production of antibodies and CD8+ cytotoxic cells.",
"In fact, to be precise, the antibody response gets ",
" after each exposure. This is because B cells (the antibody factories) hypermutate and compete with one another. Those ... | [
"If they are really completely over it, they can not actively spread it, but of course aid in the spreading of other peoples viruses as a temporary host. ",
"either way, idiots should be fired."
] |
[
"Can both pressure and vacuum exert identical magnitudes of stress inside a pressure vessel?"
] | [
false
] | The stress profile will vary based on if its pressure or vacuum, but will equal magnitudes of either i.e. 20 psi vs -20 psi (on either side of atmospheric pressure) exert comparable stresses on their container? | [
"First, -20 psi ",
"gauge pressure",
" isn't possible because atmospheric pressure is only about 15 psi. However, let's say that you'd like to compare a pressure vessel's stress profile at -1 atm and 1 atm gauge pressure, with the first condition corresponding to vacuum. You are correct that ",
"pressure vess... | [
"That's buckling mode failure -- it doesn't actually mean the material is under greater stress. "
] | [
"You can absolutely have negative absolute pressure in a liquid. Any fluid that can support internal tension can have a negative absolute pressure. Water in trees can have absolute pressures of -20 Atm."
] |
[
"How are the angles in molecules figured out?"
] | [
false
] | For example on PCl3 the angles are 107 degrees. How are these angles figured out? | [
"IR and Raman spectroscopy. Knowing the masses and measuring the IR spectra of molecules such as PCl_3 one can determine the bond lengths of the P-Cl bonds as well as the angle between these bonds. "
] | [
"in addition to the other responses here, X-ray crystallography can also measure bond angles."
] | [
"People often use computational methods to determine what the bond angle should be to adopt the lowest energy conformation. This is not always observed to exactly agree with experiments, but they're often very close.\nRemember that bonds are always stretching and bending very rapidly."
] |
[
"I remember learning about a tree species that breeds by sprouting new trees from its roots a sufficient distance from the parent..."
] | [
false
] | ...and thusly there are entire forests of this tree that share roots and are arguably a single organism. I can't find this tree on Google, can anyone identify it for me? | [
"This the one? ",
"http://en.wikipedia.org/wiki/Pando_%28tree%29"
] | [
"Bingo! Thanks!"
] | [
"You're quite welcome!"
] |
[
"How can we say \"nothing travels faster than light\" without using a frame of reference?"
] | [
false
] | [deleted] | [
"You're missing that in special relativity, velocities don't add linearly - they add like ",
"this",
". So neither astronaut will see the other one moving away superluminally, and there is never any possible circumstance in which they will."
] | [
"What you're missing is just that your classical intuitions - such as that ",
" velocities are relative - simply don't hold when it comes to relativity :) If I'm driving in a car at 20 mph relative to the ground, and another car is driving at 50 mph in the same direction, to me it'll appear to be travelling at 30... | [
"That's the thing. The speed of light is the same in all frames of reference.",
"I know, it's bizarre. It's shocking. It's never stopped being bizarre and shocking since it was discovered, but it's the truth. Different frames of reference have different definitions of time and space, this causes velocities to not... |
[
"How is it that a person can (presumably) safely hold plutonium in their hands?"
] | [
false
] | null | [
"The sample of plutonium he would've been holding is not ",
" radioactive. And as long as it's not allowed to get anywhere near criticality, there won't be many fission reactions happening in the sample either.",
"It can be held in your hands, although if you're being responsible, you'll use shielding whenever ... | [
"Plutonium is not automatically fatal. It’s jusy a heavy metal, and it’s somewhat radioactive (depending on the mixture of isotopes you have).",
"If you injest it, you’ll get sick from heavy metal poisoning, and probably get a significant dose of radiation. But otherwise, it can be handled. You should wear gloves... | [
"Interesting. That's completely turned my idea of radioactive materials upside-down! Thanks."
] |
[
"What is the most common type of planet ?"
] | [
false
] | What is the most common type among the observed planets in the universe ( Rocky, gas giants, other that I don't know about) or are they uniformly found. | [
"This turns out to be a question about ",
" more than anything. There's still enough wiggle room in theoretical models that we don't really know what we should expect the most common planets to be. However, observations don't tell us about every planet out there - they tell us about the planets that are ",
".",... | [
"They are gas planets.",
"The biggest rocky planets are probably 10x the mass of the Earth, but it's a bit fuzzy. There's a lot of planets where we know the mass, but we don't know if it's a \"Super Earth\" or a \"Mini Neptune\"."
] | [
"Are hot Jupiters always made of gas or are there Rocky planets that can be the size of Jupiter? \nEdit : is there a limit on how big a Rocky planet can become ?"
] |
[
"Can mice experience shock or be frightened to death?"
] | [
false
] | [deleted] | [
"Well, humans can:\n",
"http://circ.ahajournals.org/content/111/4/480.short",
"\nThere is better experimental evidence for a role for chronic environmental stress in cardiac disease/cardiac episodes.\n",
"http://ajpheart.physiology.org/content/273/4/H1754.short"
] | [
"I don't have any scientific merits to my name, but I have first-hand experience that this is true. We had a bit of a mice problem in my families pantry at home years ago, and one night my mother began pulling bags and other things off the Pantry floor, only to uncover a small group of about 5 mice than went scurry... | [
"Great articles, thanks!"
] |
[
"Can you be \"Star-burnt\" at night? If so, how long would it take?"
] | [
false
] | The way I take it, the first question boils down to a few mechanisms: The first of which comes from photons emitted from the sun, absorbed and re-emitted by the moon. The second comes from photons emitted from distant stars other than our own sun. From my understanding, "sunburn" occurs when photons with energies in th... | [
"It can't be affected by other light, but it can be deflected by magnetic fields. See how the auroras are created for details.",
"This is wrong.",
"The auroras are created when charge massive particles, like protons and electrons, are deflected by the magnetic field which causes them to accelerate (change the d... | [
"Even on top of this for some types of electromagnetic radiation, our sun's magnetic field will prevent some photons from entering",
"No, that can never happen. Photons don't see electric or magnetic fields (nor can they interact with electromagnetic waves)."
] | [
"Radiation being emitted in a uniform spherical distribution has an intensity fall off of 1/r",
" where r is the distance to the source. That means that if we were twice as far away from our sun as we are would result in an intensity one fourth of what we currently experience. If we take Proxima Centauri add 4.25... |
[
"What is the youngest (most recently formed) a piece of granite could be? I just read that they can be as old as 4 billion years, but it’s mind-boggling to think that I’m putting rocks that could be millions — let alone billions — of years old in the bottom of pots for my houseplants."
] | [
false
] | Seems disrespectful, somehow. | [
"Granites are intrusive igneous rocks, meaning that they crystallize from a melt within the Earth's crust before reaching the surface (as opposed to a rhyolite, which is the approximate equivalent of a granite if erupted at the surface of the Earth). The age of an igneous rock reflects when it crystallizes from a m... | [
"As of 2013",
", the youngest dated exposed granite pluton is the 1.4 Ma Takidani Granodiorite in Japan, which was dated via SHRIMP U-Pb.",
"My labmate is doing his Masters on the youngest Himalayan granite, which is an 8 Ma leucogranite in the Ramba Dome, that's the youngest I've seen in person."
] | [
"Ah yeah, I should have made it clear what Ma means, sorry about that. ",
"Yes, the rocks you pick up are likely hundreds of millions of years old. Of course, it varies depending on where you are. ",
"You actually can't really get non-igneous rocks under a million years old. Soft sediment needs to buried, compa... |
[
"In evolution, does one single specimen mutate in a certain way that's beneficial regarding its environment and then pass down the mutated genes to its offspring increasing their chances of survival, or do several specimens mutate in the same way in different locations?"
] | [
false
] | I teach science (Biology, Chemistry, and Physics) at High School, but I teach at a Life Skills level, which means my kids are between 14 and 18 but have the mental capacity of 3-7 year olds (hence my lack of focused expertise in any one single field). I have more of a chemistry background than a biology one, and while ... | [
"I think what you're asking is, does a mutation that perhaps eventually becomes fixed in a population trace back to a single individual or does it trace back to multiple identical mutations in two or more individuals within the population?",
"While it's not impossible for the exact same mutation to occur more tha... | [
"Both are possible. ",
"Multiple discrete mutations could occur within the same generation and be passed on due to increased fitness, resulting in a multitude of different alleles of the same gene in a population. If two discrete mutations essentially work the same way, it's also possible that one may work better... | [
"What you wrote seems to imply that new species arrises due to a single mutation, but that rarely happens.",
"There are cases today where speciation is still incomplete, like between wolves, dogs, and coyotes. There is no single gene that distinguishes them. The populations separated, and different traits have be... |
[
"Would it be possible for two planets to orbit one another at such a close proximity that you could jump from one to another?"
] | [
false
] | [deleted] | [
"The same force that keeps you from jumping into space is keeping Earth together. So if you could jump to the other planet, then that means that the earth itself would also end up on the other planet if there's the tiniest disturbance. And there would be because the tides caused by this situation would be huge. Bas... | [
"You are describing ",
"Lagrange points"
] | [
"NEAT! I know science and didn't know I knew science."
] |
[
"Why doesn't caffeine affect me?"
] | [
false
] | null | [
"We can't really comment on isolated incidents / personal anecdotes."
] | [
"From what I have seen, I'm not the only person to have had this happen, I am just the first to have collected data."
] | [
"Right -- we can't comment on a single observation. Perhaps you could ask a more general question like \"why does caffeine affect individuals differently?\" That has an objective answer that doesn't require speculation like a question specifically about you."
] |
[
"Do we remember everything?"
] | [
false
] | [deleted] | [
"No, for example, you don't remember the color of the volkswagen that passed you yesterday on the freeway. Things stored in \"short term memory\" do not exist forever."
] | [
"Absolutely not.",
"One clear example is in witness testimony. For a ",
", often violent, one would think that would make a fair impression on someone. At the very least, it draws our attention - one of the main factors in memory retention. However, the reliability of witness testimony is overwhelmingly bad - o... | [
"To answer this question properly, consider different types of memory. Your random school day memory is an example of episodic memory, or the \"movie of your life\" type memory. The lyrics to a songs are more implicit memory. ",
"There is some speculation to the effect that we subliminally store both these kinds ... |
[
"If I donate bone marrow to a 100 recipients (theoretically) would there be 100 other people with blood completely indistinguishable from mine?"
] | [
false
] | Inspired by the OP states the premise that marrow recipients take on the DNA makeup of someone elses blood if they recieve a marrow transfusion from a donor. If this is in fact the case, what other parts of their (recipients) genetic makeup would also match the donors DNA? and is it a 100% match or sort of a cocktail o... | [
"In order for a bone marrow transplant to occur, the recipient's own blood-producing stem cells are eradicated, so if the procedure works properly, only those stem cells from the donor (with the donor's DNA) will continue to produce blood and immune cells in the recipient.",
"Although these stem cells are limited... | [
"Actually it's probably most the white blood cell DNA. Saliva is highly enriched with white blood cells, which is good since lots of foreign material enters your body via your mouth"
] | [
"This paper",
" provides some decent information about chimerism in saliva- using mouthwash specimens they detected the donor DNA frequently over the recipient's. A ",
"followup paper",
" by a different team found that having the individual rinse their mouth out with water first and using a brush to swab cell... |
[
"Why do we need IPv6?"
] | [
false
] | [deleted] | [
"This is a very good answer.",
"Less than 30 years after IP was invented, and well before the internet became so ubiquitous, we were already having to adjust routing architectures to accommodate growth.",
"With the Internet of Things growing as it has, IPv6 will allow for more fluid development of new technolog... | [
"This is a very good answer.",
"Less than 30 years after IP was invented, and well before the internet became so ubiquitous, we were already having to adjust routing architectures to accommodate growth.",
"With the Internet of Things growing as it has, IPv6 will allow for more fluid development of new technolog... | [
"we were already having to adjust routing architectures to accommodate growth.",
"I don't know if this is true or not, but a greybeard network engineer told me once that if NAT has not been invented, the internet would have ground to a halt before 1995."
] |
[
"How do email spam filters work?"
] | [
false
] | From taking a course in statistics I learned that spam filters use obvious cue to label something as spam; like excessive dollar signs. But what else do spam filters do to determine what is and isn't spam besides obvious give-aways? For example-Do spam filters monitor if a user sends out multiple emails in a short peri... | [
"Great question!",
"The short answer is: \"Lots of different ways\".",
"Basically, spam filters will use some process (we'll talk about different kinds of processes in a moment) to categorize email as either legitimate or spam. In fact, many email clients and services have a 'learning period' where they notify ... | [
"/u/thenmar",
" is right in that nowadays, supervised learning algorithms in the form of classifiers form the basis of spam filters. This makes spam filters much more adaptable as spammers modify their messages in any attempt to circumvent them.",
"In the early days of email, though, rule-based approaches and i... | [
"/u/thenmar",
" is right in that nowadays, supervised learning algorithms in the form of classifiers form the basis of spam filters. This makes spam filters much more adaptable as spammers modify their messages in any attempt to circumvent them.",
"In the early days of email, though, rule-based approaches and i... |
[
"If I were traveling in a vehicle (or on an object, etc.) fast enough to break the sound barrier, would I hear the sonic boom?"
] | [
false
] | Or would I outrun it, as it were? What else - associated with the boom - would I experience? | [
"No. For a given speed, the shock location is fixed relative to the aircraft, like a bow wave is fixed relative to a ship. Hearing the sonic boom means that the shockwave has passed over you. Since the shock is fixed relative to the aircraft, it doesn't pass over you if you're inside the aircraft."
] | [
"Nope you wouldn't hear it! Its not that you would outrun it, it just doesn't happen in your area. You create a cone around your vehicle where the pressure wave is, but the air inside the cone is just normal air. so the boom happens in front of you, and kind of goes around you since it cant travel through that ar... | [
"Sound doesn't exist unless there's a physical medium through which its waves can travel. No sound in space."
] |
[
"Can people have different, naturally developed, antibodies for the same diseases?"
] | [
false
] | Some time ago there was a post saying that the number of random mutations of our antibodies rises greatly when we are sick, so we can develop immunity to novel pathogens. So I started wondering if when people catch, for example, Covid and then beat it naturally, or even through vaccine, do they develop antibodies that ... | [
"Yes. As you note, antibody variability arises from random mutations that alter the surface by which the antibodies bind to their target antigen. It is possible for antibodies that have different binding surfaces to still bind to the same site on a target antigen, or to different sites on the same antigen, or to di... | [
"The stronger the antibody binds to its target (antigen) the better, but different antibodies can bind with the same \"strength\" (affinity) even though they don't bind to the exact same \"part\" (epitope) of the target. It's safe to assume that different people have antibodies with very similar affinity, probably ... | [
"because we all start with a different complement of MHC genes that we inherited from our parents",
"This is true but not the explanation. MHC genes are different from antibody genes. (The antibody genes are also highly variable, though.)"
] |
[
"What are the long term effects of preventing an animal that would normally hibernate from doing so?"
] | [
false
] | Specifically; Would preventing hibernation in an animal like a bear by keeping it in a warmer climate decrease longevity or skew their mating season? Would the same be true for hibernating reptiles, fish and amphibians? | [
"Nothing bad, bears hibernate only when they need to. They don't in zoos because the food is always there."
] | [
"They can, however, starve if they are awoken early and are unable to replenish the calories they burn as a result. This can happen if bats are disturbed halfway through the winter, and don't have enough fat reserves to survive after they go back to sleep. ",
"Source."
] | [
"According to Rick Shine (in a lecture I had from him many years back during my undergrad biology course), a pretty big Australian herpetologist, for reptiles it's far safer if they don't hibernate - this is why most reptile owners won't hibernate their pets unless they are planning to mate them (hibernation trigge... |
[
"How does radioactive half life work?"
] | [
false
] | null | [
"No, it doesn't affect the half-life."
] | [
"Could you please elaborate further?"
] | [
"Putting shielding around radioactive material has no impact on its half-life."
] |
[
"How can we calculate how close Halley's Comet came to the Earth in the past?"
] | [
false
] | I understand we can get a lot from how people reported sightings at the time. Such as how bright it was, etc. However, when I look at a chart of the comet's previous sightings some of them include a number in astronomical units suggesting how close the comet was at the time. How can we work this out for some years bu... | [
"We know the orbits of Earth, the other planets, and Halley's comet. Because there's almost no drag or friction in space, it's straightforward to calculate the position of celestial objects at any time in the past or future, and therefore the separation between Earth and Halley's Comet on a given date. Within a cer... | [
"Take the current orbit and extrapolate backwards. Ideally include effects that change the orbit over time. Or get a database where someone did this already.",
"Any particular time period you are interested in?"
] | [
"Thank you for the answer. What I'd like to know is how I could work out roughly how close the comet was on the years it was visible from Earth. Is there a way you'd suggest going about this?"
] |
[
"How do we know that blue whales weigh upwards of 200 tons. How do you physically weight them?"
] | [
false
] | [deleted] | [
"The largest blue whale ever recorded was a female off the coast of South Georgia in 1947, who weighed 190 tons (",
"source",
"). It would be nice to be able to say some sort of estimation method was used, but in reality she was just killed and weighed directly. Incidentally, it is likely that the ",
"extre... | [
"If I was tasked with ball-parking their weight, this is what I'd do:",
"So if we just rough-park it as a conical pyramid, then (4.88m / 2)^2 * pi * 32 / 3 is roughly 200 cubic meters, which, with a density of 1, comes out to 200 tons."
] | [
"That's a good point, their density has to be close to the density of water, so that they can swim efficiently. And not constantly expand energy by trying to swim up or down."
] |
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