title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"What is uncertainty principle and what is it's significance?"
] | [
false
] | You want to see an electron. What do you do to see that? You shoot some photons aka light on it to 'see' it and this causes the electron to get more unstable and hence it becomes impossible to track down its original "position". Hence, the uncertainty. This is what is given in our science textbooks. It seems like it is dumbed down to it's basics. Can someone please give a more elaborate yet easy to understand explanation of the uncertainty principle and explain it's significance in physics? | [
"The uncertainty principle is a mathematical consequence of the way that position and momentum are related in quantum mechanics. Here is a slightly more accurate (but still handwavy) picture:",
"A particle with a definite momentum has a definite (de Broglie) wavelength. Something with a definite wavelength essent... | [
"It's important to remember that the uncertainty principle is just one of many (experimentally verified) ",
" of quantum theory.",
"You're correct in that the idea that \"the observer affects the observed\" is a bit simplified. It's more than that. If you prepare a system for measurement, you're going to get a ... | [
"I never quite got it, until your sine wave example. Thank you, oh person of science"
] |
[
"What does the band of muscle at the back of the head do?"
] | [
false
] | I've been looking at the muscle anatomy of the head and I'm confused. There's a band of muscle at the back of the head in between the ears and I don't know what it does. The area surrounding it seems to be mainly composed of tendons so I'm not sure why this muscle is there. Does anyone know? | [
"I assume you're referring to the occipital belly. Some believe that the occipital belly, at the back of the skull, and the occipitofrontalis muscle, at the front of the skull, are essentially the same muscle, but others classify them as two separate muscles. As far as I know, the occipital belly muscle helps move ... | [
"I’ve heard several of the facial muscles being referred to as vestigial. These come from ancestors that could wave their ears and such to (I’m presuming) ward off flies."
] | [
"This makes a lot of sense. My very nearsided family has always talked about how we think wearing glasses makes you more aware of these muscles because you often wiggle/pull your ears back to pull your glasses up, which seems like it may be the only real function of the vestigial trait"
] |
[
"How do scientists determine the gravitational pull of exoplanets?"
] | [
false
] | null | [
"Whether or not we know the gravitational pull of an exoplanet depends on how we detect it. For most exoplanets, the best we can get is an estimate of size by observing how much of a star's light is blocked when the planet passes in front of it. But without knowing the planet's density, we can't know its mass, whic... | [
"These two pieces of information tell us what effect gravity is having on the system, from which we can estimate the mass of the whole system (star+planet).",
"No. Radial velocity measurements are sensitive to the mass ratio, or more precisely (planet orbital speed)*(planet mass)/(star mass). The mass of the star... | [
"Bleh, you're right. I got lazy at the end and didn't quite remember the math that takes you from star speed and exoplanet period to exoplanet mass. Momentum is conserved, which sets up the ratio you spelled out. Kepler's third law (or Newton) and the period get you the planet's orbital speed. Thanks for catching t... |
[
"What produces the whistling sound you hear when a large bomb is being dropped or a firework is going off, etc?"
] | [
false
] | [deleted] | [
"Fireworks are designed to whistle, they basically have whistles built into them for effect which create sound as they rush through the air.",
"In war films and documentaries the sounds of falling bombs etc. are not necessarily authentic, but are added afterwards to help communicate the story. Oftentimes the orig... | [
"Bombs have a safety device which is unscrewed by a small propeller when they fall through the air. This keeps them from exploding if the plane crashes. And the propeller makes the whistling sound.",
"And as ",
"u/scroam",
" pointed out, fireworks are designed to whistle."
] | [
"Would you also count the doodlebugs or V2 rockets in this? They made a loud noise until their engines stopped. Then the psychological terror kicked in as you waited to hear where it hit. "
] |
[
"Why does torque point where it does in a spinning wheel?"
] | [
false
] | null | [
"Right, so how does it translate to the real world? Why does a symmetrical wheel appear chiral?"
] | [
"Right, so how does it translate to the real world? Why does a symmetrical wheel appear chiral?"
] | [
"My original question...\nForget torque, why is the direction of the angular momentum the way it is out of two possible, seemingly impartial, directions? Hell, even electromagnetism is applicable to this question, but a spinning object should be less \"mystifying\" so I didn't even mention it."
] |
[
"How can light be both a wave length and particles?"
] | [
false
] | null | [
"If you think ",
" weird, how about electrons? They're both waves and particles too.",
"On one level -- \"it just is\". On another...",
"It boils down to something in the philosophy of science, called ",
". It turns out that the concepts of \"particle\" or \"wave\", convenient as they are for learning, d... | [
"A good rule of thumb is that ",
". This means that any interaction with matter - absorption and emission - must occur in discrete chunks of ",
" which we call photons. For all other cases, it's often simpler to think of light in terms of EM waves.",
"Light is an electromagnetic wave - it is a changing elec... | [
"This is not correct. The field is also quantized - its components obey uncertainty relations. See ",
"this",
" (technical article).",
"Example: One cannot know both the amplitude and phase of an electromagnetic wave with arbitrary accuracy. This affects the design of gravitational wave detectors (",
", ... |
[
"I am currently taking Ranitidine (which sells as Zantac in the USA). Why are the pills so sweet to the taste?"
] | [
false
] | null | [
"Lots of pills are sugar-coated to mask unpleasant taste."
] | [
"Is it Children's Chewable Zantac?"
] | [
"Sure beats a spoonful!"
] |
[
"PHYSICS: Are there events between atomic or subatomic particles where the collision is not perfectly inelastic?"
] | [
false
] | Are there events between atomic or subatomic particles where the collision is not perfectly inelastic? This may be a silly question but my searches haven't given me a satisfying answer. Thanks! Also I'm new to posting on AskScience and couldn't figure out how to apply a field to the question. Sorry. Edit: nvm | [
"Honestly, I'm not sure I've ever heard \"perfectly inelastic\" be used to describe a collision that was not macroscopic.",
"A perfectly inelastic collision means that the maximum amount of kinetic energy is removed from the system by the collision. In the case of colliding rubber balls, this means the balls sti... | [
"Thank you so much for taking the time to answer! \nNo worries on how long you answer was, it was thorough. Which is good. ",
"I do have an additional question regarding the energy levels of electrons and photons. You mentioned that they have no internal energy level... Do you think you could elaborate on this? I... | [
"Very helpful, thank you. ",
"My understanding is that once you move beyond fundamental particle we have no measurable evidence so theories like Super String Theory take hold of possible structures. Would you happen to know if the vibrating strings described in this theory are attributed any mass or energy level?... |
[
"Does synesthesia hamper the sense it manifests in?"
] | [
false
] | Say you have a synesthesia where you see the letter A as red. You are shown a paper with a yellow A and a blue A. Can you tell that the letters are of different ink colors? Is it as easy and quick as compared to one with no synesthesia? Do you expererience both colors, only semantic or only visual or do you experience a blend or mix of them? | [
"I can always see what color letters are printed in. Like as I'm typing this, my words are clearly white. Usually the colors I see from synesthesia manifest as a translucent highlight around the word or the color would feel like it's encasing my brain. (Wonderful description, I know.) If letters or words are print... | [
"Does the fighting happen visually and is there pain involved?",
"Does it help if the whole word is one color?"
] | [
"The fighting happens semantically or psychologically. Like, for example, McDonald's is usually printed in a bright yellow, but my brain wants to see it as turquoise and red. Since the yellow is so strong and actually there, it'll cause a disagreement in my brain and it'll make it harder for me to see my brain colo... |
[
"How can I calculate the weight of a cubic meter of fat?"
] | [
false
] | I understand that there are different fats, I have no further knowledge of the type of fat... how can I roughly calculate the weight per kg / Tonne / cubicmeter? Thanks for any help, I don't know where to start on this one... | [
"Weight per kg is exactly one kilogram.\nWeight per metric ton is exactly 1000 kg.\nThe cubic meter is the only challenge. \nHere's what I found: ",
"http://www.aqua-calc.com/page/density-table/substance/animal-blank-fat-coma-and-blank-bacon-blank-grease",
"\nAccording to this, the answer is 870 kg for bacon gr... | [
"You don't ask the question very well, but I'll avoid unhelpful flippant answers and try to guess your intent.",
"First off, if you know the density of fat, you multiply that by a million, because density is per milliliter, and there are a million milliliters in a cubic meter (100 x 100 x 100). That gets you the ... | [
"Thanks. It's not about floating though. The grease separater gets disposed in cubic meters, but I have to report the data in tonnes / kg."
] |
[
"Is there a reason why we can't invent a device to objective measure pain level?"
] | [
false
] | I imagine if there was a device that could actually tell you how much pain someone is in, that would have a world changing effect on everything we know. Is there a reason why this is not feasible? What are the limitations to creating such a device? | [
"Pain can't even be defined, let alone measured.",
"Seriously, try to define pain!",
"In the end it doesn't really matter because pain is a subjective experience. It doesn't matter what caused the pain, only how much you are in and that's pretty well measured by asking the patient 'on a scale of 1-10, 1 being n... | [
"I think fMRI (functional Magnetic Resonance Imaging) can tell how much pain a person suffers. They are expensive. "
] | [
"Well I was wondering because surely something is occurring on a physiological level, even if pain was subjective, isn't there anyway to measure what physiological changes are occurring?"
] |
[
"Are telescope images of objects such as galaxies that are hundreds or thousands of light years across, are they distorted?"
] | [
false
] | My thought process is that if you look at a galaxy from an angle that would put one end of the galaxy dozens if not hundreds of light years closer to us than the furthest end, would that mean that we are looking at a distorted image? | [
"They are, but only by an imperceptibly small amount. Stars in the outer edge of a Galaxy will be moving at about 200 km/s. Their light takes about 100,000 years to cross the galaxy. So in that time stars on the far side will have moved about 70 light years, so ~1/1000th of the entire galaxy's size."
] | [
"Ah, I know what you mean.... interesting. In principle, yes. But: Huge (spiral) galaxies like the Milky Way or Andromeda are about 100.000 lightyears across. That of course that the part of the galaxy that is closer to us, is also older* than the part which is further away.",
"On cosmic time scales, 100.000 yea... | [
"Parallax measurements only bring you out a couple of hundreds to a thousand or so lightyears, because the measured angle gets soooo small, that our best telescopes can not measure it."
] |
[
"Why does a television's signal strength increase while I'm touching the antenna?"
] | [
false
] | It's happened on numerous occasions and I was curious as to why it happens. I also wanted to know how to emulate this without having to touch it to keep the signal strong. | [
"By touching the antenna, you are effectively increasing the size of the antenna. And while bigger isn't always better, this does allow TV signals to be picked up more clearly in some cases. (It could just as easily make it worse, but how often are you touching the antenna when the signal is good?)",
"You could t... | [
"If the reception is already good, you might end up adding some unwanted noise to the signal. The antenna is (almost) perfectly tuned so any change will be for the worse."
] | [
"Let's see if this gets past the mods, it's hilarious yet accurate in a way."
] |
[
"Do celestial bodies have decaying orbits?"
] | [
false
] | [deleted] | [
"If there is nothing else going on, the emission of gravitational waves makes orbit decay over time. Apart from black holes and neutron stars close together, the timescale of this process is much longer than the age of the universe. It will become relevant, but only in the very distant future. Eventually most of th... | [
"Phobos, one of Mars's moons has a decaying orbit:\n",
"what the ESA says:"
] | [
"For planets and moons the main migration is tidal and so bodies tend towards what is known as tidal equilibrium (circular orbits with aligned spin-orbit axis). This effect can increase or decrease orbital distance (depends on a number of things such as spin and orbital speeds as well as on the convective emotion i... |
[
"Why is there a very high-pitched sound coming from my CRT television? What is making it?"
] | [
false
] | Not sure if this falls under Physics or Engineering. | [
"The frequency that the CRT puts out is a direct function of the refresh rate of the screen and the number of scan lines on the screen.",
"If you take 29.97 (the refresh rate of an NTSC signal) * 525 (the vertical resolution of an NTSC signal) = 15734, which is the frequency of the tone produced by the TV. ",
"... | [
"I can confirm that all CRT monitors make this high pitch sound no matter if it is a television or a radar display. I can walk into a room and immediately tell if one is on while others in the room can not."
] | [
"Only some people can hear this noise. All CRTs TVs make the noise (That I've been around anyway), if the OP only hears it on his TV, then it would be a capacitor going, if not and he hears it on others, then it's the refresh rate of the TV.",
"How come they all sound the same pitch?"
] |
[
"How come similar latitudes north and south don't experience the same climate?"
] | [
false
] | Base on it seems like southern hemisphere locations which are equidistant from the equator are not as cold as their northern counterparts. What causes this? | [
"There are ",
" influences on climate besides latitude. At the gross scale and for this observation, the primary reason is the relative proportion of a given latitude that is land vs ocean, where the southern hemisphere has more ocean on average. ",
"Continental climates",
" generally have larger temperature ... | [
"Human geography (which sounds like the class you took) and physical geography (which sounds like the class the poster is describing) are typically two different courses. An intro geology course might also cover some of this, but depending on the course, climate might be a relatively small component."
] | [
"If you could I would encourage you to take a geography class. They should cover this in great detail. It’s incredibly interesting to me and it sounds like it would possibly be to you as well. ",
"Yeah at a macro level, latitude matters, hemisphere matters for timing, but then as you zero in on the nuances of an ... |
[
"When and how did we learn the position of the planets in the solar system?"
] | [
false
] | For example in what year did we found that Jupiter is the 5th planet from the Sun? How did we learn that Saturn was similar in size but even further and in the 6th position? | [
"Although I'd like to encourage more history of science questions here, I'm not sure how many answers you might get. If you don't get an answer, you can also try ",
"/r/askhistorians",
", ",
"/r/historyofscience",
", or ",
"/r/philosophyofscience"
] | [
"As soon as people realized the planets orbited the Sun it is pretty obvious. The time for one orbit is easy to find by watching the planets for a while and you get relative distances by assuming the planets have somewhat smooth motion in space. At the time of Kepler people had quite good relative distance measurem... | [
"You may be interested in ",
"this",
" page which gives all the details of timelines of discoveries of planets and other objects in the solar system.",
"As a side point we may not have discovered all the planets as there is still the open question of it planet x actually exists or not."
] |
[
"Does putting Vitamin E lotion on your skin actually do anything?"
] | [
false
] | null | [
"I did a pubmed search for articles with \"topical vitamin E\" in the title. There is a paper that showed that it reduced UVB (but not UVA) skin damage in swine skin, when combined with a commercial sunscreen, compared to the sunscreen alone. Other than that, studies looking at potential benefits for surgical sca... | [
"In addition, many sunscreens contain vitamin E as Tocopheryl Acetate. Just look among \"inactive\" ingredients."
] | [
"Do you strictly mean rubbing liquid vitamin E on your skin? Or a lotion that has been fortified with the vitamin?"
] |
[
"I have a keen interest in martial arts but want to know how is this possible? What's the trick? Can anyone here explain what is happening here? [Sorry its a video link]"
] | [
false
] | null | [
"(Oh hey, something on AskScience I'm actually qualified to talk about!)",
"I trained martial arts in China for two years in my early twenties. I lived as the only foreigner in a school amongst a bunch of super hardcore dudes, some of whom were part of the school's performance troupe. I've seen a 15 year old boy,... | [
"They calculated the \"force\" based solely on the speed of the bat. That's not a measurement that would pass any kind of scientific scrutiny."
] | [
"They calculated the \"force\" based solely on the speed of the bat. That's not a measurement that would pass any kind of scientific scrutiny."
] |
[
"How much does centrifugal force counteract Earth's Gravity?"
] | [
false
] | Would a person weigh less closer to the equator? Would it be possible for a planet the size of Jupiter to spin so fast that its gravitational pull is the equivalent of Earth's? | [
"0.3% at the equator."
] | [
"Reread the question; it's legit."
] | [
"You do weigh less near the equator, but it's mainly because the earth is bulged out near the equator so you're further from the center of mass. I suppose the rotation does affect your weight, but it's a very small correction. "
] |
[
"Why are blood cells red/white?"
] | [
false
] | null | [
"Interesting. Well thank you for explaining!"
] | [
"Red blood cells contain the oxygen-carrying molecule hemoglobin, which contains iron. White blood cells, however, have no hemoglobin. The iron in the hemoglobin makes the red blood cell red, and since the white blood cell doesn't have any, it's not red."
] | [
"Oddly enough, some of your \"white blood cells\" aren't white at all. Eosinophils have a pretty distinct \"fire-engine red\" color, due to certain granules they posses. Mast cells and Basophils appear purple due to their granules, and lymphocytes (T and B cells) appear quite purple/bluish because they have a very ... |
[
"How much larger would Earth's diameter have to be before life would be affected by being that distance closer to the sun?"
] | [
false
] | null | [
"The habitable zone for our solar system, for an Earth-like planet, is approximately 0.99AU to 1.688AU ",
"according to the study done by Kopparapu et al. 2013 ",
".",
"If we take the lower limit and expand such that we're 0.01AU closer to the Sun, that would make Earth's radius increase from 6371 km to 1,502... | [
"The distance between the Earth and the Sun varies by about 3% over the year, and these changes have less of an effect on the weather than the seasons. 3% of Earth's orbital distance is over 700 times its own radius."
] | [
"For those curious, the earth is closer to the sun during the southern hemisphere's summer than the northern's"
] |
[
"COMPUTERS: When you take an image off of one machine, and apply it to another (using ~Acronis) How similar are the machines/OS's/HDD's on a low level?"
] | [
false
] | We use it at my company and we are interested! | [
"Disk imaging software typically does a byte by byte copy of the original disk, so the HDD should be near identical after copying a disk image. Granted there will be small differences -- e.g., one HDD may have different number of platters, etc and map stuff to different locations. Also if you use an old hard disk... | [
"At the level where data is read/written, it may or may not be identical depending on the software. Different imaging programs work differently. For example, a desirable piece of functionality in such a program is the ability to apply a disk image to a different capacity disk than it came from (as long as the use... | [
"From a software point of view, the machines are pretty similar (assuming the hardware is close).",
"The main differences will be the hard drive serial number and network card MAC address."
] |
[
"Will the Covid vaccine go to people that have caught Covid already?"
] | [
false
] | Since the vaccine just gives your body a little piece (mRNA) of the virus would catching the actual virus do the same thing for your body? Making people that have caught Covid and survived immune to the virus since their body has already dealt with the virus and knows what to look for. I remember around June - July that nobody was sure if you became immune once you caught Covid. but with this vaccine and how it works, it would make sense that you would be immune after catching covid. So with that, has anyone heard of "Covid survivors" getting the vaccine? Or am I wrong in thinking you'd be immune after catching Covid? | [
"We don’t know how long natural immunity to COVID (that is, immunity after natural infection with wild virus) lasts, and probably the answer is something like “between three months and thirty years, depending”. Several studies have found long-lasting immunity following clinical cases of COVID, but there are also a ... | [
"Obviously it needs to be tested. But there’s certainly precedent for vaccines giving better immunity (e.g. HPV vaccines) and it should be both obvious, and supported by data, that the natural immune response to SARS-CoV-2 is extremely variable and not very predictable (though mild and asymptomatic infections tend ... | [
"Thank you for your concise and helpful answer. I was wondering the same since I've had it and had a confirmed positive."
] |
[
"What is that faint \"vortex\" you sometimes see called or caused by?"
] | [
false
] | Sometimes when I look at the sky (or some other uniform area) I see a 'vortex' in the center of my vision. It is akin to that starfield screensaver on old Windows computers. Does anyone else ever see this? What is it called? PS Sometimes in the dark I also see noise. To me, it looks like a huge conveyer belt of very tiny SpaghettiOs (red colored too!). Is that a known phenomenon as well? | [
"Haidinger's brush",
"? ",
"That, being an artifact of polarized light in the sky, would not show up in just any blank area."
] | [
"Hmm, that is an interesting phenomenon, but it's not quite what I see. In my case, the vortex is quite animated, as if you have the sensation of patches of vaguely greyish shapes traveling inward into a point."
] | [
"Here is a starting point:",
"http://en.wikipedia.org/wiki/Closed-eye_hallucination",
"By the way, I see the exact same thing. As far as I know, not many people see it. I am not sure if this is because they cannot, or because they simply don't notice it."
] |
[
"Do all stars have the same photospheric composition?"
] | [
false
] | I googled this question and only received vaguely related articles and blog posts. I would assume the photospheric composition of a star changes whit the different stages of a stars life cycle (O to M classes) but I would like to know for sure rather than accept false information. | [
"For a main sequence star, the outer layer generally remains constant until it reaches the red giant phase.",
"Red Dwarfs would steadily grow in helium as convection currents mix their core with the outer layers.",
"If the star is between .4 and 4 solar masses, the star will undergo a set of thermal pulses wher... | [
"It depends on the chemical environment in which the star has formed. The photospheric composition represents roughly the composition of the initial cloud of gas that formed the star. This composition may vary from one star to another, depending on the enrichment its initial cloud has received from stellar winds/su... | [
"We do also observe changes over the star’s lifetime. Some red giants have significantly more carbon or other elements in their outer regions due to deep convection zones bringing up fusion products from the interior. It’s not a huge amount in absolute terms, but it can cause a pretty significant change in the spec... |
[
"Evolutionary advantages of viruses?"
] | [
false
] | I'm currently watching BBC Horizon - Are We Still Evolving and they are discussing viruses. A virus is effective at producing copies of itself and thus pass on it's gene via evolution. The thing that troubles me is fatal viruses. If fatal virus kill their host, there is technically a point when viruses will run out of hosts before it learns to jump to a new species. Would that not make it a disadvantage to be a fatal disease? Of course there is a complex interplay between viruses evolving possible host species as well as hosts evolving defense mechanisms, but it seems that if a one species, fatal virus existed, it would spread rapidly killing the host species and killing the virus itself due to lack of hosts. Is the interplay so complex that the death and defense of each species balance each other out? Won't one organism eventually lose given enough time or does evolution work too fast to have this happen? | [
"On one hand is a virus that infects and goes to a high serum titer (uncountable zillions of copied viruses in the blood, semen, gut, mucous, and tissues) causes enormous systemic symptoms and sheds everywhere through diarrhea, vomit, coughing, etc. This virus will spread fast and very likely impair or kill the hos... | [
"Ebola virus",
". Thats why its so rare. 'coz its so fatal. It manages to only come up as short outbreaks, and scientists suspect also that the only reason why it even persists is because its main host is not primates but some other species where its not so dangerous.",
"But your question is right: fatal paras... | [
"Here's a couple of advantages off the top of my head:",
"1) If you were going to insist that they're around because they add some sort of advantage, you could make an argument that they promote allele diversification. Viruses, especially retroviruses are responsible for a good fraction of gene duplication and su... |
[
"Where and how did the Spanish flu start, and what caused it to spread so rapidly?"
] | [
false
] | I know that ww1 was a major contributor for the spread of it but what else, and I keep finding different theories on what animals caused it, some say horses and some say pigs. So reddit please help me out here. | [
"This was posted on Reddit a few months ago and, if iirc, the ",
" answer is....",
"It seems to have begun in a rural area of Kansas. It would've stayed there, for the most part, if not for World War 1. Infected young people went to boot camps and shared the flu. Then most of those people were transferred to ot... | [
"The exact origin of the 1918 Spanish Influenza is unclear. There is some evidence that it may have emerged in rural Kansas in early 1918 and spread from there due to the movements of soldiers enlisting, training, and being sent overseas. There are other proposed possible origins, including China in 1917 or France ... | [
"The reason it spread so fast initially, is most likely because the people getting infected (especially soldiers) were living in extremely close quarters and probably didn't use any hand sanitizer (cause it wasn't around, just so no one gets confused).\nWhen it spread in the countries there were a lot of injured pe... |
[
"Why are planets and moons spherical? I haven't seen any planets that are oddly shapes so far. Similar thing to asteroids, why are they not as perfectly spherical as planets?"
] | [
false
] | null | [
"A sphere is the most compact form of matter\n So any large lump of matter will tend to form a sphere as gravity pulls everything to the center of mass, packing it as tightly together as possible ",
"Slightly smaller masses like most asteroids or smaller moons (Martian moons Phobos and Deimos for example) can ... | [
"Any rock bigger than about 300 km diameter, will have enough gravity to pull itself into a sphere."
] | [
"Any rock bigger than about 300 km diameter, will have enough gravity to pull itself into a sphere."
] |
[
"Why do some of my wife's favorite foods nauseate her now that she's pregnant?"
] | [
false
] | I know that this is not uncommon. In my wife's case, she loves barbecue. Pulled pork, brisket, slow smoked, the whole bit. But, now she's pregnant and even thinking about slow cooked pig is enough to get her feeling sick. What's the physiological reason for this? What evolutionary purpose would this serve? | [
"From an evolutionary perspective, \"morning sickness\" is thought to serve a protective function for both the mother and the fetus during early pregnancy. Before we had such luxuries as pasteurization and proper food storage, foods such as meat were more likely to contain parasites and pathogens, and toxins in st... | [
"Thanks. Well known phenomenon, happens to many if not most women. I've never heard an evolutionary explanation, but it makes a lot of sense."
] | [
"As Iheartgogurt said, while morning sickness early during pregnancy is normal, severe morning sickness, or ",
"hyperemesis gravidarum",
" is not typical or beneficial. It is thought that this could be caused by an infection with a bacteria that can live in the stomach called ",
"Helicobacter pylori",
". ... |
[
"Is it possible that all (or all but one) elements exhibit radioactivity in all isotopes?"
] | [
false
] | Bismuth was thought to be a stable element for a long period of time until it was found to be very weakly radioactive. Although the decay rate is more or less insignificant for all practical purposes, it still exists. Is there any physical law that states that certain isotopes will never decay, or is it possible that all elements are radioactive (or decay to the simplest element possible), but their decay rates aren't detectable? | [
"I wish there were a place where we could ask expert scientists about things."
] | [
"Would the existence of proton decay imply that all isotopes can eventually decay?"
] | [
"Every element has at least one radioactive isotope. Some heavy elements have no stable isotopes. But there are some nuclides (about 300 of them) which will truly ",
" decay, to the best of our current knowledge.",
"There is no law against them decaying per se, but we've never observed them decaying, and have n... |
[
"Why are self antigens not considered foreign?"
] | [
false
] | Antigens are usually thought of as something foreign causing an immune response, then why doesn't our body attack our self antigens. If we have self-antigens that are tolerated, then they aren't really antigens, since they don't cause harm? I'm confused Thank you | [
"Something is not an antigen by itself. To a bacterium, its antigens are just proteins that do something. To our immune system, an antigen is something that an antibody binds to, either free floating or on a T-Cells membrane (that‘s how they detect antigens). Self-antigens are just normal (surface) proteins that th... | [
"The field generally does refer to \"self epitopes\" as \"self antigens\". Epitope refering to a specific peptide sequence and antigen referring to an epitope that is recognized by the immune system. Immune cells are recognizing and tolerant to self all the time. Autoimmunity is obviously the outlier. \nTo maybe mo... | [
"But wouldn't that just be an epitope?"
] |
[
"Why do babies have a distinct baby smell?"
] | [
false
] | Why is it that babies all smell pretty much exactly the same when all adults smell a different kind of foul (without any deodorant/perfume/cologne)? Is it because we load them up with baby powder? I'm sure not all parents do that(but maybe it's hidden in their items, like diapers?), so I can't figure out why they all smell very similar. Basically, I'm asking if there is a biological explanation behind their smell? | [
"http://www2.citypaper.com/columns/story.asp?id=2139",
"It seems men may like it even more than women. As a man, I can say babies do smell great. I can see this helping to change behavior from hunting and mating to taking care of a child. A trait like that could be selected for by evolution in the very care-in... | [
"Was the study measuring the father's response to the smell or random men's response? I ask because I, and every other non-father I know, find the baby smell repulsive, and being in the presence of babies stressful and unpleasant. An infant seems to induce as much stress in me as it induces love in the mother - t... | [
"(just being silly here) What if his trait would have provoked his ancestors to murder other men's babies? Thus if he even makes one kid, and he kills everyone else's babies, he wins!"
] |
[
"Do people with tetrachromacy perceive electronic displays differently?"
] | [
false
] | So I've been interested in for a while now, and while fiddling with my monitor settings, a thought occurred to me: The pixels of LED monitors are made up of red, green, and blue LEDs. If someone with tetrachromacy can see a fourth primary color, would trichromatic monitors seem to display the wrong colors to them? For instance, if they took a photograph with a digital camera and then viewed it on the screen, would the colors be "off" from what they see in reality? | [
"Yes in theory - a tetrachromat by definition would need four fixed primaries to match an arbitrary target color (like something they see in the world).",
"But as far as the literature is concerned, ",
"there's evidence for a single tetrachromat",
" (and it's not perfectly convincing, though that is a cool pa... | [
"That's true, but RGB only allows for each color to be emitted at 256 discrete levels of intensity, which ultimately results in an inability to fully reproduce every visible color. The link I provided demonstrates that clearly "
] | [
"Well for one, RBG monitors despite showing all of the primary colors cannot actually reproduce all the colors we can actually see as shown here ",
"http://en.m.wikipedia.org/wiki/Color_space",
". So even for those with only the three standard cones see colors on a monitor in a more limited way than in real lif... |
[
"Do foods have different caloric values for different animals?"
] | [
false
] | null | [
"Not a full answer to your question, but an example: Humans cannot digest cellulose, the main components of the cell wall in plants. Some animals like Cows however can (with the help of all their stomachs and their microbiome). Thus the nutritional value of plants like grass is vastly different between cows and hum... | [
"Yes, exactly. Cellulose is a complex sugar and humans cannot break it down, it is indigestible for humans (fiber). Cows can break cellulose down, and those broken down sugars can then support the Cow's growth."
] | [
"Yes, exactly. Cellulose is a complex sugar and humans cannot break it down, it is indigestible for humans (fiber). Cows can break cellulose down, and those broken down sugars can then support the Cow's growth."
] |
[
"There is a video of a man folding a piece of paper with a hydraulic press 7 times. The 7th time seems to essentially break the piece of paper, what happened here?"
] | [
false
] | Here is the video I'm referring to. | [
"After a quick literature search, the answer appears to be rather boring and straightforward: most likely what happened was the following:",
"1) Paper is largely made up of a forest of irregular ",
"cellulose",
" fibers, ",
"as shown here at high magnification",
". When pressure was first applied, the fib... | [
"Citations?",
"Edit: No idea why I'm being downvoted here. The video shows something really interesting and all the answers so far are basically speculation.",
"Edit: Well I guess the votes have swung the other way now. Thanks Science fans!"
] | [
"Except the press didn't shatter it. Rather, it seems to have momentarily liquefied it, and when it resolidified, it did so into a more brittle substance. "
] |
[
"Please explain what \"quantum tunneling\" is, and why does it happen."
] | [
false
] | I only know one thing, that companies that make processors like Intel, AMD, Nvidia and others have trouble making processors smaller than a few nanometers (smallest now is about 22nm as far as I know, I personally posses a 32nm one) because at that scale a phenomenon called "quantum tunneling" causes electrons from transistors to jump wildly across the circuit (correct me if I'm wrong). Why does this happen? | [
"Take an egg carton and cut off the top. Then put a marble inside one of the dimples. No surprise, the marble will stay there forever because it doesn't have enough energy to jump over the top and into another dimple.",
"Now, shrink everything down to the size of electrons and nuclei. The marble represents the el... | [
"I think in your analogy the bullet still has enough energy to punch through the wall even when its thinned. Tunnelling is stranger than this. It is as if without shooting the bullet, you gently place the bullet right up against the wall, and later, you find that it is on the other side!",
"The bullet is the elec... | [
"Quantum tunneling occurs when some quantum object crosses an energy barrier that it shouldn't be able to cross classically. For example, if we think of a bowling ball as our particle and a hill as our barrier then if you roll the ball towards the hill, the ball will either roll up to the top of the hill and back d... |
[
"What exactly is happening when someone uses skin lotion/moisturizer?"
] | [
false
] | I guess I’m asking how skin cells interact with the chemicals in the lotion and where those chemicals go once they’re “absorbed”. | [
"While the answer depends on several factors (including what's getting applied to the skin, where on the body it's being applied, what vehicle (or topical agent type - think cream, lotion, ointment, foam, etc) is being used, and what the composition/active ingredient(s) are in that vehicle), let's start with the ba... | [
"Yep, there's a difference! 100% oils or waxes are called 'occlusives', meaning they form an inert barrier right on top of the skin that completely blocks TEWL. While great at keeping water in, they can be a bit messy to apply - think of petroleum jelly and the like. ",
"Conversely, lotions are vehicles made of ... | [
"The top layers of your skin are dead skin cells, lightly adhering to the layers below. One they dry out, there is a lot of space in between. Moisturizer gets sucked into this space, so you end up with a more adhesive matrix of dead cells in oil. Still dead though."
] |
[
"Hand sanitizers claim to kill ~99% of bacteria. Does this mean that 1% of the population of all strains survive? Or does it mean that 1% of the strains of bacteria will always be impervious to alcohol?"
] | [
false
] | [deleted] | [
"Alcohol kills bacteria exponentially. I don't remember (read: google couldn't find) the precise numbers, but after x amount of time, 90% are dead. After 2x that time, 99%, 3x, 99.9%, and so on. As you can see from that math, you'll never 100% sterilize something using alcohol - at least not in a practical way. How... | [
"Fire is 100% effective ;)"
] | [
"Fire is 100% effective ;)"
] |
[
"why does bar soap lather differently when it's nearly gone?"
] | [
false
] | null | [
"Here is the answer from a soap maker. When soap is made commercially it hardens and crystalizes from the center out. The seed crystal that forms originally for the crystalline structure of the soap to form around it has a different structure and makeup, IE the core of the soap is different than the fatty exterior.... | [
"The most likely explanation I can think of is that, the more you expose the soap to tap water, the more it exchanges sodium ions for calcium and magnesium ions that are in the water. This effect should increase with water hardness (a measure of the concentration of calcium and magnesium ions in tap water).",
"ht... | [
"Can you show that this phenomenon actually exists?"
] |
[
"Why do I cough whenever I clean my ears?"
] | [
false
] | So, every time I clean my ears with Q-tips, I cough, sometimes rather violently. Sorry if this is a stupid question, but can someone please explain this? | [
"More specifically.",
" It's called the Ear-Cough or Arnold Reflex. One of my small contributions to Wikipedia was adding this very subject (self-serving pat on my own back, I know)."
] | [
"You're digging too deep and stimulating the ",
"vagus nerve",
". "
] | [
"Listen to this man, I'm just a physicist ... "
] |
[
"\"Greenhouse gas levels highest in 3 Million years\". Okay… So why were greenhouse gases so high 3 million years ago?"
] | [
false
] | Re: Carbon dioxide concentrations in the Earth's atmosphere are on the cusp of reaching 400 parts per million for the first time in 3 million years. The daily CO2 level, measured at the Mauna Loa Observatory in Hawaii, was 399.72 parts per million last Thursday, and a few hourly readings had risen to more than 400 parts per million. ''I wish it weren't true but it looks like the world is going to blow through the 400 ppm level without losing a beat,'' said Ralph Keeling, a geologist with the Scripps Institution of Oceanography in the US, which operates the Hawaiian observatory. ''At this pace we'll hit 450 ppm within a few decades.'' | [
"At the risk of spamming this across reddit today (I posted it ",
"here",
" in response to another post), the IPCC's Paleoclimate chapter does an excellent job of explaining changes in climate during the past, and their implications for modern climate change:",
"http://www.ipcc.ch/publications_and_data/ar4/wg... | [
"There are several ways:",
"Stable isotope ratios of growth rings in speleothems (stalagtites and stalagmites);",
"Stable isotope ratios in oceanic foraminifers (for which we have time series reaching back several tems of MY);",
"Direct measurement in gaseous fluid inclusions in both ice-core, vadose zone cem... | [
"The question isn't about natural or normal or not. Its about the ability for human civilization (and other species, though there will be big winners and losers among them) to live happily under the rapid change. Human civilisation wasn't around 3 myo, and will likely suffer immensely if the world rapidly changes t... |
[
"How are viruses and bacteriophage affected by convection currents and Brownian motion in regards to adhesion?"
] | [
false
] | [deleted] | [
"Consider that the bacteria is not a perfect sphere, it lacks a uniform density. It is not an attribute-less particle like is expected for Brownian motion.",
"Right, and small nonspherical bodies don't actually orbit the sun because ",
" can only happen between spherical objects or point masses. ",
"All you a... | [
"I get that your latest point(this is after you finished with the claims about scale and energy which were vague to the point of lacking all content) is that flexible bodies which change shape over time and as a function of interactions with water can not be perfectly described by a Wiener process. This is a trivia... | [
"All I argued is that is isn't a strict Brownian function. Not that modelling it as such is not feasible. Just that you have to make the simple distinction on definition that what we are describing may have merit modeled as such, but the two are not simply the same.",
"The OP claimed that viri and bacteria unde... |
[
"What gives a steel cable so much more tensile strength than a steel rod?"
] | [
false
] | null | [
"I thought for sure someone would give you the answer. But I saw lots of just dead wrong answers, like a cable doesn't have higher strength than a rod, that it's more flexible, or that it's denser. But tensile strength, which is the same thing as ultimate tensile strength for a wire, is fracture load divided by tru... | [
"Metallurgist here: the general rule of metals is that beating the shit out of them (or forcing them into shapes, like a wire) makes them \"stronger\".",
"By \"stronger\", we mean that you need to apply more stress (= force per unit of surface area) before it deforms or breaks. Ceramic is pretty strong, which is ... | [
"Can you explain this like I’m not a materials scientist?"
] |
[
"With the winter in North America being so long and cold this year, have any invasive species expanding northward been set back? E.g. Southern Pine Beetles?"
] | [
false
] | I remember reading which stated that there were issues with pine beetles migrating north. I'm wondering if this cold winter has mitigated the problem, and whether there are any other cases of invasive species whose impacts may have been temporarily mitigated by the cold. | [
"A couple of studies have concluded the cold weather has put a serious knock down, but not eradication, the emerald ash borer and asian murmurated stinkbugs ",
"http://www.washingtonpost.com/national/health-science/winters-freeze-stopped-ash-borers-and-stink-bugs-cold-but-theyre-primed-for-a-comeback/2014/03/02/9... | [
"Aside from the cold weather, are there any potential predators that might be able to migrate north alongside of them?"
] | [
"Not sure if resilient. They didn't get all the trees, and cones were left on ground. They took things out pretty quick. Copper-Basin TN is where I am talking about. The sapling hardwood trees (Oak, Hickory, and Poplar) took off with all the pine trees down or rotting.",
"If really concerned make a journal and d... |
[
"Why has early detection of diseases via dogs not found widespread use in medicine?"
] | [
false
] | I have heard how dogs can detect diseases such as cancer or now covid with a surprisingly high accuracy. However I have not seen widespread use of dogs in such a manner. | [
"Consistency issues.",
"In some cases, researchers don't know exactly what chemical compounds the dogs are detecting. That remains a hurdle for training better sniffer dogs but also for designing better detection devices.",
"Competition with AI detection devices. Robots are pretty good at this stuff too, plus... | [
"I would guess the skepticism of the medical community is only compounded by that of patients who would likely take the news that a dog has sniffed them and decided they've got cancer about as well as a kick in the teeth. As humans, we quite like our official and complex processes; the more official and complex it ... | [
"The studies look good",
"https://journals.sagepub.com/doi/abs/10.1177/1534735405285096",
"",
"But, its not like they have dogs just sniff 1000 people and try to find breast cancer. That wasnt done, and presumably wouldnt have just a high success rate. So basically the studies arnt well controlled to demonst... |
[
"If I'm standing in a completely red room that has a white light source, will a green ball appear black to my eyes?"
] | [
false
] | So from my understanding, the reason a red object appears red to us is that it absorbs all visible light frequencies except for red, which it reflects. This goes for all pigments/light combinations. For the sake of this question, lets say that the green ball has no direct line to the white light source, so that all the light hitting the green ball has to bounce off of something red first, thus becoming "red filtered." I suspect that the green ball will still appear green. What am I missing here? | [
"Human vision takes a lot illumination into account when deducing color. That is if a lamp is yellow it doesn't that much make you change your opinion on the color of the objects it illuminates. There is a neat optical illusion picture where a object projects a shadow on a chess board. If you compare pixel by pixel... | [
"Here's a link to the illusion you mentioned: ",
"http://web.mit.edu/persci/people/adelson/images/checkershadow/checkershadow_illusion4med.jpg"
] | [
"The only thing you're missing is that most objects in reality will reflect some level of all wavelengths of visible light. Sure, it might be predominantly reflecting red, but those walls will still reflect some measure of other wavelengths too."
] |
[
"How will E.T. see us ?"
] | [
false
] | We have been transmitin television waves for some years as seen in this . So, if there is a planet with intellengent life in that range, they should be able to watch our TV signals. But a) Will they have to point their anntenas to exactly our location (or maybe our location 50 years ago) ? b) Will the signal be strong enough to receipt it ? c) Are we doing the same with every new planet the Keppler discovers ? Are we trying to "watch" them ? | [
"Man, I feel so much more comfortable about my crush on you right now..."
] | [
"Good lord. Where even to begin. It's entirely true that there really are women working in science. Everything else I can think of about that novel is pure imagination."
] | [
"Once you get out to a distance of about three light years, terrestrial radio and television signals are attenuated to the point where they cannot be distinguished from noise.",
"The closest star is more than four light-years away.",
"So no, there are no little green men watching Hitler open the Olympic games."... |
[
"How does time near the speed of light work for two different frames of reference?"
] | [
false
] | Ok, so I know the classic example of an astronaut leaving earth traveling at near the speed of light and then returning to find that time has passed much quicker on earth than in his speedy spaceship. However, in my astronomy textbook it says that if there are two bodies moving relative to each other and each body had its own clock, both clocks would appear to be ticking slower than the other, depending on which frame of reference you take. So, my question is this: Wouldn't the people on earth be traveling at near the speed of light relative to the astronaut and thus be experiencing time at a slower rate from their perspective than the astronaut? | [
"Ah this is the classic ",
"twin paradox",
".",
"Special relativity states that reference frames that are uniform are equivalent. i.e. they are either traveling at a constant speed or stationary. ",
"The thought experiment is: if you are on a bus that's traveling at a constant speed, it is indistinguishable... | [
"This is the reason that the ",
"twin paradox",
" is called a paradox. The astronaut on his journey will see time progress slowly on earth- however, when he turns around to come back to earth, he changes his frame of reference. When he changes frame of reference, many of his coordinates get relabeled. In a sens... | [
"Just want to say that you don't need general relativity to resolve the twin paradox. Special relativity can handle the accelerating bodies."
] |
[
"How do we assign time values (in seconds, years, etc.) to events that occurred long before the earth began rotating and orbiting the sun? And are those estimates given in our present fame of reference or the local reference frame?"
] | [
false
] | When I hear that something happened X seconds or years after the Big Bang, I always wonder how that number was arrived at, when seconds and years are based on events that didn't begin to happen until just a few billion years ago. It seems like these figures could be derived from something like the hyperfine transition of hydrogen, but even hydrogen atoms didn't exist until 380,000 years (there it is again) after the Big Bang. | [
"First I'm going to be pedantic and say that the second is determined in terms of transitions of a Cesium atom, not Hydrogen. To actually answer your question though, even though Cesium certainly didn't exist in the earliest moments of the universe we still know how long those events took because we have made calcu... | [
"Why does the hydrogen need to exist before you can use it as a measurement?",
"It's almost like saying I don't have a meter stick with me, so using the metric system to measure distances is therefore invalid."
] | [
"Wow. That was exactly the kind of answer I was hoping for. Thank you."
] |
[
"How are program installer files so much smaller than the program they install?"
] | [
false
] | In order for it to install something, all of the data has to be there, right? So, how does it work? | [
"In some cases, the installer may hold a compressed version of the data. The installed files are decompressed, so they take up more disk space.",
"However, the compression factor usually only gets to about 2 or 3 for typical software. If you're seeing a much larger discrepancy than that, then probably what's happ... | [
"This, and I'll add that install programs these days often are a channel to grabbing the real data from some authorized location on the internet. In other words, not all the data has to be there if you have an internet connection.",
"You install a small program, a \"download client application\", that creates a ... | [
"Another common one you'll see with some of the big apps, like Office, is it's preinstalled and locked out, the installer just unlocks the existing application (and doesn't actually install anything, except maybe a start menu icon)."
] |
[
"Making it's rounds on Facebook: Sodium Fluoride added to our drinking water is poisoning us. Any truth to the claims?"
] | [
false
] | I'm not a scientist, but I immediately get skeptical when someone cites a "holistic medicine" website to prove their claim. The following has been posted on quite a few of my friends' walls and I am just wondering if the claims have any real substance. Offspring of pregnant animals receiving relatively low doses of fluoride showed permanent effects to the brain which were seen as hyperactivity (ADD-like symptoms). Young animals and adult animals given fluoride experienced the opposite effect -- hypoactivity or sluggishness. The toxic effects of fluoride on the central nervous system was subsequently confirmed by previously-classified government research. Two new epidemiological studies which tend to confirm fluoride's neurotoxic effects on the brain have shown that children exposed to higher levels of fluoride had lower IQs. A study published in Brain Research shows that rats drinking only 1 part per million fluoride (NaF) in water had histologic lesions in their brain similar to Alzheimer's disease and dementia. All pics are for sharing... so if you wish to use them to help spread the truth, please do! ♥ Reached the 5,000 limit so here's my other page... Feel free to share your posts! UPDATE: This is my first time using , and I am extremely pleased with the quality of these responses. Keep up the good work! | [
"Some personal informatio:\nI work with large amounts (kg quantities) of NaF for the past year in the form of FLiNaK (NaF-LiF-KF) fluoride salt. I've inhaled it a ton. I've definitely had more than 1 ppm in me. ",
"Some scientific information:\nThe MSDS says the oral lethal dosage for 50% of humans is: 71 mg/kg... | [
"http://www.sciencedirect.com/science/article/pii/S0022113905002599#sec3.5.1",
"A lot of the health effects are inconclusive. The population data supports the fact that it is generally safe, but it can cause a well documented cosmetic defect known as dental fluorosis."
] | [
"This is perfect. Thank you so much!"
] |
[
"Why are neanderthals considered a seperate species to humans if we were able to breed with them and produce fertile offspring, to the point that a large percentage of modern human DNA is derived from neanderthal DNA?"
] | [
false
] | null | [
"Species is a pretty mushy term and there is many species where things are just species because we want them to be or find it useful. ",
"Like a polar bear and a black bear can breed but no one is super interested in making them the same species because it's more useful to just pretend because they are different ... | [
"To expand on this, human paleontology in particular is rife with named species that probably should not have their own name. We don't have DNA for the vast majority of them (Neanderthals are recent enough to be an exception), so everything is based on anatomical differences, and many of these differences are real... | [
"Species definitions vary, but typically feature reproductive isolation as part of the definition, not outright reproductive incompatibility. i.e. if two populations don't typically encounter each other (on separate islands maybe) they might be considered species even if, were we to artificially put them together i... |
[
"If cold-brewing coffee takes nearly 12 hours, would continuous mechanical stir/agitation significantly accelerate extraction?"
] | [
false
] | For example, putting water with coffee grounds into something like a slurpee machine then letting it run for a while? Or, for an even more vigorous stir, a mixer? If this does indeed accelerate extraction, can we take some wild guesses on how much faster the process could potentially be? Does the possibility exist that with sufficiently energetic stirring, one could obtain similar results to the 12-hour "static" process in a matter of minutes? | [
"Generally, stirring the solvent speeds up whatever is going on in it. If you place a sugar cube in water, it dissolves rapidly at first but then as the water around it becomes saturated the dissolution slows down as molecules diffuse away from the sugar cube. Diffusion happens rapidly over short distances but slow... | [
"Not minutes but faster. But for something like coffee there are other complexities. The issues involved are how fast something comes out of the grounds into solution and the amount of stuff in the water at the time. The more stuff that has dissolved in the water the longer it takes to extract. That is why stirring... | [
"It seems that every cold-brew method I've read about is essentially some form of maceration (as opposed drip coffee, which is percolation). Intuitively, the maceration speed of a stirred \"solution\" should increase many times over a static one, but I'm specifically interested in the behavior of compounds found in... |
[
"Why doesn't the sun have a metal core?"
] | [
false
] | Or does it? I realize the metals may not be liquid or solid, but seems to suggest that the metal composition of the inner and outer layers of the sun are roughly the same, suggesting it doesnt' have a metal core. But the same article suggests the sun isn't churning out elements from its center because it is radiative, rather than conductive. Shouldn't it have quite a bit of the heavier elements that were floating around the solar system while the planets were forming? | [
"A bunch of it did end up in the sun, 2% of the sun's mass is heavy elements, not 2% of the total heavy elements in the solar system are in the sun. Huge difference ",
"Here",
" is a pie chart comparing the masses of the different objects in the solar system, notice anything?",
" post originally said what it ... | [
"The sun indeed was born with some metals. Gravitational settling would tend to make the heavier elements \"sink\" (I am not saying that heavier things fall faster; that is not how gravitational settling works).",
"There is a timescale associated with gravitational settling. I actually don't know what physical pa... | [
"Well, I can accept that they'd spin off all across the solar disk, but I'd think at least a ",
" of the metals would have ended up in the sun."
] |
[
"How do Hard drives of the same physical size have different memory capacity?"
] | [
false
] | Say you have a 2.5" laptop HDD. How do HDDs of the same physical size, (such as 2.5" or 3.5") have such varying memory capacities? I know there are different numbers of platters but you can't really fit more than 4 in a standard case i would assume. Is the servo for the read arm just more sensitive? If this is true, can a lower capacity HDD be "recycled" into a higher capacity one by slapping on a higher resolution read arm servo and special drivers? | [
"There are several different factors. One of course is the number of platters. But the magnetic medium on the discs, the field strength of the write heads, the sensitivity of the read heads, the placement accuracy of the heads, platter vibration, etc. all determine the raw bit density that can be put onto a platter... | [
"And what are the differences in production cost when you build a 500gb hdd vs. a 1000gb one?"
] | [
"Also, how different (if at all) is the design? "
] |
[
"Why is \"clean coal\" technology so difficult? What are the limitations?"
] | [
false
] | [deleted] | [
"Aren't most of the byproducts too heavy to be released into the air ",
"The main byproducts of the combustion of coal are CO2 and H20. The lesser products include SOx (various states of oxidized sulfur). All of these are \"released into the air.\"",
"\"Clean\" means scrubbing the exhaust of coal-fired indust... | [
"One other thing is that mining coal is incredibly dirty and is not addressed whatsoever with the \"clean coal\" technology. Coal also has big pools of fly ash that have been known to spill and leak thousands of cubic meters of sludge all over the land."
] | [
"Clean coal is easy on a technical level but if it costs more than solar or wind its not very useful."
] |
[
"Why does biodiesel produce less emissions than petrodiesel?"
] | [
false
] | I imagine it must have to do with the chemical structures of the different molecules, but I can't find anything that confirms this. | [
"Oh, well there are likely to be fewer sulfur compounds in the total process. The sulfur doesn't really get to your tank of gas but it is a part of the oil that comes up that needs to be cleaned out. Although nowdays most of the sulfur is extracted and used rather than just burned into the atmosphere anyways. Essen... | [
"It produces less CO2 emissions. Because the carbon comes from plants, where it comes from the CO2 in the air. So no net CO2 emission.",
"Digging coal/oil up out of the ground and burning it ",
" lead to a net increase in CO2."
] | [
"Oh. I guess I just misinterpreted the information I was reading. I assumed that they meant it produced less CO2 and other kinds of dangerous emissions. I'm less impressed with biodiesel now. Thanks for clearing that up for me. "
] |
[
"Effects of solar gravity..."
] | [
false
] | Does the gravity of the sun counteract the gravity of Earth to any degree? If so, is there sun based gravity conflicting with the Earth's affecting us at daytime when we are facing towards, i.e. being able to jump a few millimeters higher and the opposite at night? Would this effect be more pronounced for example on a moon of Jupiter where the large body is much closer? | [
"Solar gravity is negligible compared to Earth's gravity for a person on Earth. The acceleration due to gravity at Earth's surface is 9.81 m/s",
" . The acceleration due to the sun's gravity for a person on Earth's surface is",
"(Gravitational constant)*(mass of the sun)/(distance from Earth to the sun)^2\n",... | [
"Moreover, you need to remember that the Sun is pulling Earth too almost as much as it pulls you. Think what will happen if you hold a bowling ball and have a lego figure \"standing\" on the under side of it and then drop both. Earth pulls the both of them just as much and they'll stay together. Similarly the Sun p... | [
"Another way of putting it is that the Earth itself is orbiting the sun, so it is essentially in a free fall around the Sun, along with everything on it. It's kind of like the way you feel weightless in a free-falling elevator. So, the tiny differences in gravity (the 5*10",
" m/s",
" you calculated) that the E... |
[
"Found this on the beach and can't identify what it is. Help?"
] | [
false
] | [deleted] | [
"I am pretty sure it is not wood (or petrified wood)."
] | [
"It looks like a really worn clam shell, possibly ",
", which can grow quite big. I remember finding these a lot in North Carolina"
] | [
"It seems way too heavy and rocky to be wood, even impregnated with something. It's also wearing away in a pattern that I don't ever see on driftwood."
] |
[
"Why does drinking methanol (CH3OH) cause blindness while drinking ethanol (CH3CH2OH) doesn't?"
] | [
false
] | Even though the difference between the two is only one carbon. | [
"The compound causing the blindness is actually not methanol, but formic acid, created from methanol in a metabolic process called toxication. Formic acid is a nerve toxin that acts through damaging mitochondria, and the optic nerve seems to be particularly vulnerable to its toxicity. Though, with doses only a litt... | [
"In principle, yes. You want to keep the oxidising enzymes busy while the methanol is eliminated in another way that does not yield formic acid. "
] | [
"Diverse, or none at all. If the methanol is not metabolised, it will be excreted through the urine and maybe stool in it’s original form. Takes long though, it is quite lipophilic and thus can freely diffuse. "
] |
[
"What is the physical state of victims of cardiac arrest after being woken up?"
] | [
false
] | null | [
"I used to be on the code blue team when I worked in acute care hospitals and no, the person who has been revived after a cardiac arrest doesn't just get up afterwards. They generally look quite shocked afterwards and are taken to ICU because their condition will be guarded until they're stabilized. I forget the e... | [
"Cardiac arrest often causes or is caused by damage to the heart muscle (typically, part of the heart isn't getting enough blood/oxygen and starts to die).",
"It takes a week or so for this damage to heal (as much as it's going to - it's common for some portion of damage like this to be ... | [
"usually after a cardiac arrest a person is quiet confused (if not unconscious) due to the fact that brain's (as well as the other organs) is not well maintained during , then the patient is placed under surveillance in a intensive care unit, since the cardiac arrest is prone to occur afterward (especially if the c... |
[
"How close can two stars be without absorbing each other or colliding? Is there a standard distance that makes them a binary system?"
] | [
false
] | null | [
"I would love to see an artists rendering of this."
] | [
"I would love to see an artists rendering of this."
] | [
"I read the Wikipedia article but I guess I'm not all that smart. Does this mean that theoretically a body such as a moon could one day turn into rings around a planet if it moved within the Roche limit?"
] |
[
"If I could physically manipulate atoms, how much force would it take to smash or combine two?"
] | [
false
] | The question is hard to word properly, and I can't help but think I'm misunderstanding how atoms work, but imagine if I was somehow able to hold a hydrogen atom in one hand, and a couple oxygen in the other. With impossible accuracy, would I be able to clap them together and make water or even function as a particle accelerator/smasher? I remember reading a while back that the force of the LHC is something like a mosquito running into you, so it got me thinking about if it would take a similarly weak physical force to smash atoms together if only we could actually manipulate them at that level. A related question that might be the basis for my misunderstanding is if combining hydrogen and oxygen (or any other combination) could even be done physically or of it's some other quirky feature of atoms that wouldn't work if simply smashed together. | [
"So would smashing two whole atoms together just make a tiny explosion, and would I be able to produce the force necessary with my hands? ",
"I wasn't really thinking about specifically what the LHC was doing, just that the energy was related to something as small as a mosquito hitting me. That got me thinking ab... | [
"Warning: Not a particle physicist.",
"First, for colliding hydrogen and oxygen to make water, that's not exactly what happens. When you add a certain amount of energy to hydrogen and oxygen (the activation energy), they are able to break up and recombine to form water and heat. This reaction is not a direct coll... | [
"From what I understand it's more about the speed you can clap rather than the force.",
"The repelling force of charged particles like electrons is based on ",
"coulomb's law",
". Basically the equation says that the repelling force approaches infinity when you get really really close together. Although, with... |
[
"How deep in the ground can we find microbial life?"
] | [
false
] | The soil microbiota has a very important role in many processes such as nitrogen organication, the production of methane and so on. Is there true limit in depth we can find microbes or are extremophiles able to basically colonize the whole crust? | [
"Multicellular life has been found up to ",
"3.6 kilometers deep",
" and microbial life ",
"at temperatures of 102C",
". It's reasonable to suggest that life might be found even deeper.",
"There are probably a few limits to consider:",
"We're not sure if life can survive in environments above the boilin... | [
"Correction: It's 122 deg C at around 200 times pressure at sea level, still liquid phase of water. ",
"http://www.pnas.org/content/105/31/10949.full.pdf",
" (from wikipedia)"
] | [
"As long as there is an energy source and it's physically possible for bacteria to make it down there, I don't see why not. ",
"Crust is ~40km thick and we've only ever drilled 12km down, so it will be a while before we can ever verify it either way. We've found them present 3km down, and the super deep borehole ... |
[
"Is the military myth true that you don't hear the artillery/mortar shell that kills you?"
] | [
false
] | this was inspired by another question that was asked that if an atomic bomb went off near by you wouldn't see, feel or hear it. So I was just curious if there was any scientific evidence that could prove whether or not you would hear the mortar/artillery shell that kills you. | [
"It's no myth. Most artillery shells travel faster than the speed of sound. You, or the area near you, get hit before the sound reaches your ears.",
"Personal experience. While at field artillery school at Fort Sill Oklahoma there was a battery practice firing nearby. The shells passed directly over our position ... | [
"You probably wouldn't hear the explosion that kills you, the shock wave would probably kill you before anything.",
"Artillery and mortars are fired at high angles, usually, the sound takes the shortest path. Indirect fire rounds go way up and then come down, they may leave the tube traveling faster that the spe... | [
"You're ",
" underestimating the amount of energy released in a nuclear blast. You will be ",
"."
] |
[
"How does Aspirin inhibit platelets but other NSAIDs don't?"
] | [
false
] | Both ASA and NSAIDs such as naproxen or ibuprofen inhibit COX and prostaglandins and all that business but ASA inhibits thromboxane release of platelets and decreases their aggregation. Is it COX 1 vs 2 or is it more complex than that? What makes ASA so special? TL;DR Whats the molecular mechanism behind ASA inhibiting platelets and but other NSAID don' | [
"The other NSAIDs do inhibit platelets. It depends upon the ratio of COX1 to COX2 activity of the NSAID. Aspirin, naproxen, ibuprofen are all anti-platelet due to COX 1 inhibition, but aspirin is an irreversible inhibitor of COX1 and so the duration of effect is longer (the lifetime of the platelet). For ibuprofen ... | [
"One extra thing, even the so called \"COX-2\" inhibitors should be more accurately named \"mostly COX-2\" inhibitors because all the NSAIDs inhibit both COX-1 and COX-2. The COX-2 inhibitors mostly inhibit COX-2 but they'll also have a small amount of COX-1 effect. Likewise of the older nonspecific COX inhibitors ... | [
"Sweet thanks"
] |
[
"Reasurance theorem? Mutual masturvation of primates?"
] | [
false
] | null | [
"Hi gigilo_down_under 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 t... | [
"How many bloody things do i need to add to a post? Question marks, flairs... im on the Android app. With no ability to edit headings"
] | [
"There isnt a flair for zooology"
] |
[
"Are the same type of cells found in humans relatively the same size across all humans, or do they vary in size? Similarly, are the same type of cells the same size across species, and other animals, e.g. is a liver cell in a dog the same size as a liver cell in a cat?"
] | [
false
] | null | [
"Not sure about \"regular\" cells but spermatozoa very in size a lot comparing different species. I did research on fish reproduction and sizes would vary between fish species, though they would be somewhat similar. They differ a lot from other species I also did a bit of research on or saw on the field such as dog... | [
"Different types of blood cells (red and white) tend to be the same size across a species unless there is pathology. This is why we can have machines that do automated cell counts, and also why they can be wrong with disease (I.e. leukemia). Cell sizes and morphology vary quite a bit between different species, so o... | [
"There's obviously a lot of variation in cell size within an organism and even within a tissue. You have neurons with a 2 meter long axon, but also neurons of less than 10 micrometer total size. But this does not correlate with animal size, so smaller animals don't have smaller cells, they just have fewer of them."... |
[
"Electromagnetism is generally presented as wave phenomena. What is the particle (photon)-based interpretation of wireless communication, or of two charged particles repelling each other?"
] | [
false
] | I've just completed a mid-level university course in electromagnetism under electrical engineering, covering uniform plane waves, transmission lines, antennae, waveguides, optical fibres, etc. The entire subject matter was presented by interpreting a disturbance in the electromagnetic field as a wave, e.g. for a basic plane wave, the electric field strength and direction could be given by: E(x,y,z,ω,t) = A e e e . Similarly, we are shown that a charged particle creates a disturbance in the E field, and hence will exert a force on other charged particles. My question is, how should I think about these phenomena as an interaction between matter via photons? I understand that matter particles can be considered in a quantum sense to be entirely described by a wave that represents the probability of that particle's superposition collapsing to that point. Does a similar understanding apply to photons? If so, how does this wave (which seems to be a lot like a field to me) relate to the electric and magnetic fields as I understand them now? And if particles are constantly shooting photons at each other to convey the effects attributed to the electric and magnetic fields, where does the energy for these photons come from? Maybe related, or maybe I am reading the wrong discussions -- I have seen some talk online of electrons having a "cloud" of virtual photons. How can this possibly work if photons travel in a straight line and always at c? Cheers | [
"In principle, interaction of matter via photons ",
" the interaction of charged objects through changes in EM fields.",
"Let's say you have some static distribution of charge in some volume of space. This distribution generates constant electric fields with constant energy that we might as well call 0. Now, if... | [
"I may not have have understood some of your post, but I hope I will answer your question.",
"Actual photons are definitely described by a wave function, but not really the quantum-mechanical kind. The problem is that quantum-mechanics doesn't work really well with the concepts of absorption and re-admittence, an... | [
"So a photon is really just virtual?"
] |
[
"What happens when you go without sleep?"
] | [
false
] | Is it true that you can 'go crazy' if you go too long without sleep? How long would that take if it is possible? What is the mechanism by which this takes place? And how long would it take someone to die without sleep? | [
"The longest any one person has stayed awake without the use of any stimulants was 11 consecutive days. Supposedly, people have broken that record, but none of them have been scientifically verified. The individual suffered from moderate sleep deprivation symptoms, but did not die, nor reported any long-term issues... | [
"Theoretically, yes. Though I'm not sure if such a study has been performed. I'd be willing to bet that if stimulants had been used in the aforementioned study, the subject might have been able to stay awake much longer. Constant administration of methamphetamine would probably do the trick, but of course you're lo... | [
"Very extreme cases of insomnia can limit your sleep entirely for years ",
"Al Herpin",
" , ",
"Thai Ngoc",
". Also, studies have shown that it's not the actual lack of sleep that makes someone go \"crazy\" but the lack of the REM stage of the sleep cycle. I recently read a study (that must have been perfor... |
[
"Question on perpetual motion"
] | [
false
] | [deleted] | [
"Nobody really disagrees that a system into which you're pumping energy indefinitely can sustain motion indefinitely. However, that's not what \"perpetual motion\" has come to mean.",
"Perpetual motion machines are those that can produce more energy than they consume. Your friend is not proposing one of these. So... | [
"I don't think he's using the magnet to power the rod - I think it's there as a magnetic bearing. ",
"And if you have something spinning on a frictionless bearing in a perfect vacuum, yes, it will spin forever. But that's still not a perpetual motion device any more than any space junk floating forever in space ... | [
"Yeah, its possible for something to move forever if the energy in the system doesn't change forms. But thats a highly ideal (and useless) scenario."
] |
[
"How do you calculate the motion resulting from a sound wave?"
] | [
false
] | In other words, lets say you have a sound wave at a known pitch, amplitude, etc, going through an object of known mass, etc. Is it possible to calculate the size of the resulting vibrations? If so, how? Thanks. | [
"What you're essentially asking is how does a sound wave in air behave when it becomes a soundwave in a material. Well in many ways, it's a similar process to how light interacts with materials. In this, you can even reach a quantum description of sound in materials in the form of ",
"phonons.",
"How these wave... | [
"Thanks for responding. Is it safe to assume the frequency of the vibrations in the material is equal to the frequency of the vibrations of the air particles? If a sound wave carrying a pitch of middle C (ie, 261.6 cycles per second, no harmonics) goes through air, then a wall, then through more air, is it all v... | [
"Frequency is always constant with waves. The wavelength and velocity change."
] |
[
"Why does my coffee look like this?"
] | [
false
] | null | [
"Hi wandering_grizz 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... | [
"‘Chemistry’"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"/r/AskScience",
"For more information regarding this and similar issues, please see our ",
"guidelines.",
"listed in our wiki!",
"If you disagree with this decision, please send a ",
"message ... |
[
"If it takes time for nerve impulses to reach your brain and be processed, is your body in the future as compared to your conscious?"
] | [
false
] | null | [
"Yes!"
] | [
"That is also correct. Especially when you consider the fact that information from different senses is processed at different speeds (e.g. auditory is faster than visual, pain, especially from far away limbs takes a (relatively) long time to reach your brain). Also consider the fact that a lot of information that w... | [
"I feel like this has big implications; we're not living in one point in time, but in a period in time. ",
"Am I coming at this from the wrong angle? "
] |
[
"Why do some parts of the body seem to be more prone to cancer?"
] | [
false
] | I'm especially thinking of breast cancer and cervical cancer in women, what makes those parts so vulnerable? | [
"Cervical cancer is actually less common--the reason it's often emphasized is that many instances are preventable.",
"In general, the most common cancers are in areas that are subject to rapid cell turnover, are acted on by hormones that impact growth, and are exposed to environmental compounds that cause either ... | [
"Here's a ",
"list of the most common cancers",
" divided by men and women and ethnic group. You can often see interesting environmental trends. You'll note, for example, that while colorectal and breast tend to be common in women across ethnic groups, stomach cancer tends to correlate with high salt diets. ... | [
"Women who have breastfed are actually at lower risk, ",
"http://onlinelibrary.wiley.com/doi/10.1111/j.1582-4934.2005.tb00350.x/abstract"
] |
[
"What is the smallest theoretical size a nuclear fusion reactor capable of 'breakeven' could be?"
] | [
false
] | [deleted] | [
"Went looking for a small design I saw a while ago and came across this fairly well done blog post:",
"http://www.ialtenergy.com/spherical-stellarator.html",
"The UST-1 is the design I saw, smallest I've ever seen. And the guy that makes it is such a pure engineer it gives me hope. ",
"edited since I found hi... | [
"There is the reactor size and the then there is the support stuff. In the NIF holorum and the Z-machine wire net, the reaction device is millimeters in size, but the external drivers are gigantic and weigh many tons."
] | [
"The holorum is millimeter sized. I've toured the NIF and seen one. The reaction after being hit by the lasers stops a few tens of nanoseconds after the initial compression and fusion. The plasma has not grown by much more than a few more millimeters. The chamber to do this in on the other hand is meters across. I ... |
[
"What can I put on ice such that a second layer frozen on top will separate easily?"
] | [
false
] | I'm planning an ice sculpture but can't build it where I want to present it, and since it's going to be very heavy, I'd like to be able to separate it into layers. If I freeze the first layer, then smear something hydrophobic (butter?) on the ice before filling up the rest of the mold, will they be easily separable? What are other common household hydrophobes? (I hope this question is sciency enough...) | [
"How about a physically intact barrier like wax paper or saran wrap? If those aren't tough enough you could do polyethylene sheeting (trash bag material, if thin. you can get thicker at hardware stores) or even something like a tarp."
] | [
"I look forward to this thread helping me store individual cooking size portions in my freezer. ",
"If I may request some answers more generic than OP's specific scenario (sculptures)?"
] | [
"I immediately thought of painting drop sheets, which I imagine are polyethylene as well."
] |
[
"What is morning breath and what causes it?"
] | [
false
] | null | [
"Bad breath (and even body odor) in general is caused by bacteria. On the tongue, the back is relatively dry and not really affected by brushing, rinsing, etc. This creates a very pleasant environment for bacteria to thrive, and they produce malodorous compounds, which accounts for the vast majority of bad breath. ... | [
"So despite my brushing and flossing, there is still too much bacteria build-up while I'm sleeping? Is this due to food in the diet, (like too many simple sugars) or are there multiple factors?"
] | [
"Right, sort of. It's not that you're doing a bad job or anything, it's just that normal brushing and flossing doesn't reach the back of the tongue, and that's where all the bacteria hang out. It's not that they're building up, but they secrete smelly compounds, so the longer you leave them there to do their thing,... |
[
"How Do Inward-Rectifying Calcium Channels INCREASE \"Resting\" Potential In Pacemaker Cells?"
] | [
false
] | I understand that less inward-rectifying Ca2+ channels is responsible for the higher mV "resting" potential of pacemaker cells (and consequently keeps the fast Na+ Channels inactive), but how does that make sense? The inward-rectifying Ca2+ channels are responsible for uptake INTO the cells. By having less of them, would it not mean that there are less positive Ca2+ ions going into the cell, thus the charge would be MORE negative? Additionally, as a bonus question, would the decrease in intracellular calcium due to less of these channels affect the rate /force of contraction, given the need for Ca2+ to release calcium from the SR via CICR? | [
"Where did you come by these ideas? If they have come from a lecturer then perhaps I am wrong but from my understanding pacemaker cells function differently to how you suggest. I will use cardiac pacemaker cells as an example which will hopefully help explain.",
"If you scroll down to figure 4 here (",
"https:/... | [
"Great info in there. I'm relatively familiar with the phases of the action potential. What I'm referring to is (supposedly) why the \"resting\" potential is -60 rather than -80 or so. I've read it's because there are less inward-rectifier potassium channels, but that doesn't make any sense to me."
] | [
"Do you have the source for that? If I can see that it might help me to explain your question better.",
"The reason why the membrane potential is as it is will be a consequence of the dynamics of all the channels involved."
] |
[
"Can someone explain what's exactly going on in yesterday's Astronomy Picture of the Day?"
] | [
false
] | This is the picture that I mean: Apparently, there was a solar eclipse on 1st September and it is a time lapse shot of the same. However I don't quite understand how this time lapse shot worked. My doubts: Is that the sun we're seeing in different phases? It looks like the moon to me! Why does it look like the moon? If that indeed is the sun, then what is the bright yellow object in the lower left corner of the image? (I still feel the white object in phases is the moon and the sun is in the lower left hand corner. But then the 'lunar' eclipse makes no sense!) Would highly appreciate if someone with knowledge in photography/astronomy can enlighten me what is going on in the photo. | [
"Yes, it is the sun. It \"looks like the moon\" because the sun is VERY bright and these photos were shot with VERY dark filters which allow the camera to actually capture the detail of the sun and not a big bright orb as you are used to seeing in photographs.",
"Yep, that is the sun, I am guessing at sunrise.",... | [
"I may be mistaken, this isn't so much as a 'time-lapse' as a photographically altered image, solar eclipses typically last 7 minutes in totality (that's the circle of light 19 images down). ",
"So, what's happening?",
"Yes, that is the sun, no it's not in different 'phases' as much as it's undergoing an eclips... | [
"Yes, the foreground from all the other shots would be entirely black because of the aforementioned dark filter :) ."
] |
[
"Why haven't any plants evolved the ability to move around, crawl walk or otherwise?"
] | [
false
] | [deleted] | [
"Because there is no evolutionary pressure to do so. They already have a perfectly well adapted means of travel, their seed dispersal mechanisms. ",
"There isn't an \"extreme advantage\" to movement. Movement is an extremely expensive operation. There are plenty of animals who move as little as possible. Cats are... | [
"Movement is extremely energy costly. The energy that a plant would need to expend in order to move to a \"better\" location would be extremely higher than the energy it would gain.",
"http://what-if.xkcd.com/17/",
"Is a good breakdown of how much energy an animal (cow in this case) could gain from photosynthes... | [
"Some plants do have the ability to move, think tumbleweed for example. Other plants instead of moving take advantage of more of their surroundings. Venus flytraps eat bugs to get essential nutrients, and cactus have evolved protections against extreme weather and dryness for example. "
] |
[
"How did sleep evolve so ubiquitously? How could nature possibly have selected for the need to remain stationary, unaware and completely vulnerable to predation 33% of the time?"
] | [
false
] | [deleted] | [
"It also should be noted that remaining stationary and unaware is the ancestral state for animals and all multicellular eukaryotes.",
"Awareness and behavior are fairly remarkable evolutionary innovations, really."
] | [
"I don't know the answers to most of your questions, but I just want to point out that for something to evolve \"ubiquitously\", it only really needs to evolve once, in a common ancestor. And if it seems to have obvious maladaptive disadvantages, it must have some other adaptive advantage.",
"EDIT: So these threa... | [
"This is an obvious, but very interesting observation."
] |
[
"When they mapped the human genome, what is that? If everyone has different genes, was the mapped genome one person or an average or a \"perfect\" one?"
] | [
false
] | null | [
"Everyone's DNA sequence is different. Even identical twins may be slightly different due to gene copy number variations, or due to mutations occurring during development. However, on average, about 99.5% of our DNA is similar to all other humans. Since the human genome is about 3 billion base pairs long, the varia... | [
"Not very different at all. IIRC, human DNA and chimpanzee DNA is something like 98% identical. Remember though, that our genome contains about 3 billion base pairs, so that 2% difference is actually 60 million base pairs. Between two different humans, DNA is over 99% similar, but that <1% is still millions of base... | [
"The biggest implications are its uses for identifying where exactly certain genetic mutations come from, and what genes do what. While we may look drastically different to one another, the genes that make up our appearance are minuscule in comparison to the number of genes that control everything else that makes u... |
[
"Is it possible for a single volcanic hotspot to create features of the Yellowstone hotspot (specifically, fertile plains due to ancient ash beds) and the Hawaiian hotspot (specifically, island building)?"
] | [
false
] | I'm working on a new world building project, and one of the major ideas of the region I'm creating is a volcanic hotspot creating a volcanic archipelago (much like Hawaii) across an inland sea or a large oceanic bay. However, I'm wondering what the land would look like on the adjacent land where the hotspot had been active before moving under the water. I understand that a typical shield volcano doesn't really produce huge clouds of ash, instead producing lots of lava which builds land. Something like Yellowstone, on the other hand, erupts explosively, leaving a large caldera that can later be filled in, creating fertile lands like the plains of Idaho. Do these features ever appear from the same hotspot? How are these related to volcanoes on islands like Monserrat, which, while capable of land building, also seem to erupt explosively? Finally, could a hotspot capable of island building exist under a continent, or is it factor of thinner oceanic crust? How thin would continental crust have to be to have such a volcanic system exist? | [
"well, first we have to discuss what a hot-spot actually is. A hotspot is not material travelling from deep, it's a thermal anomaly from the D\" that transmits thermal energy to the surface in a very concentrated area. ",
"When this thermal energy reaches the crust, one of a few things can happen: You can end up ... | [
"The size of the hotspots are just about the same. The reason that the hotspot trace on a continent is 'larger' because of the composition of the continental crust. Instead of spewing out a less viscous material as soon as it is heated, it heats up a much larger area. ",
"You can theoretically make an island chai... | [
"Ok, so a couple of followup questions. What happens to a hotspot of Hawaiian size when it travels across a continental plate? I assume that the Yellowstone supervolcano's hotspot is a dramatically larger/deeper anomaly then Hawaii's hotspot.",
"I was originally hoping it would make sense to end up with a mountai... |
[
"Is pregnancy between the ages of 35 and 40 really a considerably higher risk?"
] | [
false
] | I've always heard that pregnancy over ages 35 (often called Advanced Maternal Age) is significantly more dangerous for both the woman and the baby, due to the higher risks of miscarriages, preeclampsia, gestational diabetes and decrease in fertility rates (as said , and , for example). But, I watched this , from "Adam Ruins Everything", which provides evidence that the risks of getting pregnant between the ages of 35 and 40 don't increase as much as warned by the majority of doctors. So, what's the truth about pregnancy after 35? If women could have babies until they were 40 without taking any more risks, it would be better to their careers. | [
"Genetic counselor here. The historic reason for 35 being the magic number is that when amniocentesis was first introduced, the risk of a complication due to an amnio was the same as the age-related risk of the baby having Down syndrome. ",
"Now, the risks of amnio are significantly lower (ultrasound guidance, pr... | [
"“Advanced paternal age” (not sure how this is defined, possibly > 40?) is associated with an increased risk of de novo mutations and specifically an increased risk for dominant FGFR and Noonan spectrum disorders. ",
"These are rare conditions however, so the overall risk to the fetus is lower than having a chrom... | [
"Just adding to this, nondisjunction can happen on lots of chromosomes, but many of them won’t thrive and spontaneously abort. You might just experience a heavy period, and you try again. We hear about chromosomes 21, 18, and sometimes 13, because those chromosome errors can still be compatible with life and be bro... |
[
"Do electric cars have a measurable weight difference after they deplete their batteries?"
] | [
false
] | null | [
"2 micrograms, for the Tesla Roadster."
] | [
"As far as I know you apply it just like in any other case, for example a spring weighs slightly more when compressed due to the (relatively tiny) energy it is storing."
] | [
"Only those with fuel cells, since they use atmospheric oxygen as one electrode (whether they get heavier or lighter depends on whether they exhaust reaction products into the atmosphere or retain them as solid or liquid)."
] |
[
"Would it be possible to condense all daily nutrients into a single block of food?"
] | [
false
] | You often see in Sci-Fi (maybe just 50s B movies) in the future people eating food that's just a cube. I know each person is different even the two genders have different caloric requirements but could it actually be possible to have all daily nutritional requirements concentrated into a small block? | [
"It would certainly be possible since we can list them out and could just homogenize them together. The problem comes with actually using it as our only source of sustenance. There are a lot of writings that discuss (mostly) NASAs research into minimization of food for long-haul space travel. (Mary Roach's book ... | [
"Nutraloaf",
" is(was?) served in prisons as punishment. "
] | [
"It already exists, and zoos and medical labs feed it to their monkeys and chimps. It's called Purina Monkey Chow. ",
"(I've tried it and tastes horrible)",
"Purina makes a wide variety of nutritionally complete foods for various sorts of mammals. They also have Pig Chow and Carnivore Chow (I did not try those.... |
[
"Does low blood sugar have an effect on blood pressure?"
] | [
false
] | [deleted] | [
"You should ignore that answer entirely. That’s some Ancient Greek level understanding of science right there, meaning it’s entirely wrong. I’m not sure if ",
"/u/bugsybunny14",
" just thought they’d give it their best guess or what, and it’s a shame because the question is a good one. I’ll post a reply to your... | [
"Glucose (sugar) tends to be really sticky. It especially likes to stick to proteins, and this process is called glycation. It's hard to undo glycation, so high levels of blood sugar over time will continually glycate protein components of different organ systems. Glycation is not harmless, because the addition of ... | [
"Eating less sugar does not really cause low blood sugar, at least in the way you're probably thinking about it. The body has an extremely sensitive and complicated way of maintaining adequate blood sugar and will make it if necessary from carbohydrates, proteins, and fats elsewhere in the body, mostly in the liver... |
[
"Sperm... Apart from being male or female, does each sperm carry a unique genetic makeup or would I be this good looking whichever sperm got there first?"
] | [
false
] | null | [
"A normal male human has 23 pairs of chromosomes. Each sperm will get one of the two chromosomes from each pair. Which means there are 2",
" different combinations (2",
" = 8,388,608), barring genetic defect and potential mutations."
] | [
"Each sperm is different. They carry some general basic stuff. For example let's say you are heterozygous for widows peak. It is possible that one sperm has the dominant while the other the recessive allele. There's more to the mechanics of variation in sperm production, I don't remember it all too well from last s... | [
"Recombination/crossing over during meiosis would most likely produce this variation. It wouldn't be very fun if all sperm cells were the same."
] |
[
"Would the geographic center of a tectonic plate be the least earthquake-prone spot on that plate?"
] | [
false
] | Or is it more the makeup of the underlying rock that makes an area less likely to experience quakes, regardless of how close it is to a fault line? Or perhaps a combination of both? | [
"Not necessarily. To understand why, we need to think a bit more about how plate tectonics works. The idealized view of a tectonic plate is a portion of lithosphere that is internally rigid and non-deforming that moves coherently with all of the consequences of its motion (i.e. deformation, earthquakes, etc) occurr... | [
"The response above is only a partial answer. The likelihood of an earthquake to occur is not only controlled by the presence of faults and the stress state, but also by the strain rate, i.e. by the rate at which the plate is being deformed. We know from earthquakes that are induced by oil and gas operations that t... | [
"Good point, strain rate does play an important role. Though it's worth pointing out that in some places it's been argued that intraplate seismic zones have comparable strain rates to plate boundaries (albeit still on the low end), e.g. ",
"this paper",
". Similarly, going off just estimation of hazards, these ... |
[
"AskScience Panel of Scientists"
] | [
false
] | Calling all scientists! Please make a top-level comment on this thread to join our panel of scientists. The panel is an informal group of Redditors who are professional scientists or amateurs/enthousiasts with at least a graduate-level familiarity with the field of their choice. The purpose of the panel is to add a certain degree of reliability to AskScience answers. Anybody can answer any question, of course, but if a particular answer is posted by a member of the panel, we hope it'll be regarded as more reliable or trustworthy than the average post by an arbitrary redditor. You obviously still need to consider that answer here is so check sources and apply critical thinking as per usual. You may want to join the panel if you: You're still reading? Excellent! Here's what you do: We're not going to do background checks - we're just asking for Reddit's best behavior here. The information you provide will be used to compile a list of our panel members and what subject areas they'll be "responsible" for. The reason I'm asking for top-level comments is that I'll get a little orange envelope from each of you, which will help me keep track of the whole thing. Here's a good chance to discover people that share your interests! And if you're interested in something, you probably have questions about it, so you can get started with that in . isn't just for lay people with a passing interest to ask questions they can find answers to in Wikipedia - it's also a hub for discussing open questions in science. I'm expecting panel members and the community as a whole to discuss difficult topics amongst themselves in a way that makes sense to , as well as performing the general tasks of informing the masses, promoting public understanding of scientific topics, and raising awareness of misinformation. As long as it !!! EDIT: Thanks to ytknows for our fancy panelist badges! :D | [
"I bet this is giving the Grammar Nazis fits right now."
] | [
"Position: Research scientist (postdoc)",
"General field: Astronomy",
"Specific field: Extragalactic astrophysics, observational cosmology",
"Research interests: Galaxy evolution over cosmic time, star formation in the distant ('high-redshift') Universe, the connection between gas behaviour and star formation... | [
"PostDoc Experimental Particle Physics. Currently on ATLAS , did PhD on IceCube."
] |
[
"Why do we get a feeling in our gut/chest when experiencing very strong emotions?"
] | [
false
] | For instance, when experiencing embarrassment, nerves... Love. Is this just an accident, a biproduct of our physiology; or is there an evolutionary reason for it? | [
"The gut has more nerve endings than the brain, and a much higher concentration of neurotransmitters which help to regulate gut function. A flood of neurotransmitters such as serotonin and norepinephrine, caused by strong emotions and resulting in a temporary increase in gut neuronal activity, is likely the cause o... | [
"I study a region of the brain called the insular cortex for a living. It is intimately involved in both the perception of bodily states and emotional awareness. The predominant theory among my colleagues is that the two are linked.",
"The first real question is, \"what are emotions, and why did they evolve?\" Th... | [
"Maybe ",
"this",
" thread and ",
"this",
" thread on ",
"/r/askscience",
" can answer some of your questions"
] |
[
"Why can't a charged object be approximated by a point charge at the object's \"center of charge\"?"
] | [
false
] | When we were learning about gravity in Physics, we learned that an object can be treated as if all of its mass is concentrated at its center of mass. Since gravity and electromagnetism are both inverse square laws, why can't we treat charge this way as well? | [
"A spherically symmetric charge distribution ",
" be approximated in this way, as long as the observation point is outside the object."
] | [
"A spherically symmetric charge distribution has exactly the same electric field as a point charge. ",
"For a non-spherically symmetric distribution, you can still approximate the field by a point charge. For any charge distribution with a net charge, Q/(k r",
" ) is the leading term in the multipole expansion.... | [
"If it’s spherically symmetric, it’s still the same.",
"If not, you can expand in multipoles. At short distances, higher multipoles will become significant, and the approximation will break down."
] |
[
"What is the highest grade a wheeled vehicle could climb theoretically?"
] | [
false
] | Scenario: vehicle on Earth, no artificial down force | [
"If you have enough centripetal acceleration, you can drive through a loop-de-loop, or (usually diagonally) ",
"around a near 90-degree slope",
". ",
"If you're moving very slowly, then your options are going to be a little more limited."
] | [
"Theoretically, anything up to but not including 90 degrees (perpendicular to the ground) is possible, with unbelievably sticky tires and an almost impossibly low center of gravity.",
"In reality, above about 30 degrees of incline, gravity starts to make things a bit difficult."
] | [
"As long as the vertical sum of the normal force vector and the friction force vector exceeds the force of gravity, it will climb.",
"The vertical friction is directly related to the normal force, and the normal force is just the force of gravity times the cosine of the angle of the slope.",
"Theoretically, as ... |
[
"What is \"Metallic\" taste?"
] | [
false
] | null | [
"When you touch iron or copper (and to a lesser extent zinc and some other metals) and then smell or taste metal on your hands, you're sensing a chemical called ",
"1-octen-3-one",
".",
"The role of 1-octen-3-one in the taste of metal was only determined recently (2006). Full paper:",
"http://onlinelibrary.... | [
"Neither – the taste they have in common is not metal or blood but another chemical made from body oils/sweat in the presence of metal or blood."
] | [
"It's theorised that this smell is related to our ability to smell blood which forms the same chemical in contact with skin.",
"So blood doesn't taste metallic, but metal tastes like blood?"
] |
[
"How do E&M instruments which require extreme precision account for the Earth's magnetic field?"
] | [
false
] | From what I know, Earth's natural magnetic field is constantly changing, although the changes are extremely small. (Except for when it "flips".) So how does an instrument account for this? You can't just "zero it out" like you can with a mass scale, because it might change afterwards, right? | [
"You can't just \"zero it out\" like you can with a mass scale, because it might change afterwards, right?",
"Earth's magnetic field (1) is weak enough and (2) changes slowly enough that it can effectively be \"zeroed out\" for many experiments. In order for Earth's magnetic field to be problematic your experimen... | [
"This is actually an issue for people developing very sensitive magnetometers. I believe there's a group where I work actually dealing with nT field measurements. They need to use mu-metal chambers and specific materials inside the chamber so as not to produce unwanted fields."
] | [
"While you can't 'zero it out' at the sensor unit, you can subtract noise of any kind from a data set if you have some way of measuring JUST the noise (i.e. 'everything that isn't the thing you want to measure').",
"Shield one sensor against the thing you want to measure, and compare the reading from that against... |
[
"How do you weight things in zero g?"
] | [
false
] | Lets say two hundred years from now you make a quick trip to "Geostationary Quality Foods" for the roast you're making for the holiday seasons up in your spankin new space station mansion and you buy some turkey breast by the pound. How on Earth (well, actually "how in space" I guess) are they supposed to weight it to charge you? | [
"Put it at the end of a spring balance of known length and swing that turkey... For a certain given spin rate (angular velocity) you will read a force that is proportional to the mass. Yay centripetal acceleration."
] | [
"Well... implementation details :-P",
"You can always fix instruments to minimize disturbance. You can constrain the string to one axis using a cylindrical of some sort around it. You can tie your turkey to a rigid spring whose vibrational axis has be confined to a single axis by a smooth sheath. You could us... | [
"Remember 'weight' is just a measure of the force produced by a mass being accelerated by gravity. So you are really just looking for the mass of the object.",
"Mass equals force divided by acceleration. So basically they could add a force to the turkey and see how much it accelerates? You could still tell how ma... |
[
"Is it possible to cancel out AC current the same way sound gets cancelled with an inverse wave?"
] | [
false
] | I was wondering since both AC and sound are waves. I know that the way sound cancelling headphones work is by simply playing an inverse wave of the sound it is trying to cancel. This way the two waves cancel each other out, and silence is formed. Are we able to do something similar with ac current where we would match the frequency to "cancel" any current? | [
"/r/AskScience",
" frowns upon short answers but yes, yes you can. AC signals have a phase that varies in time and space and to a good approximation can superimpose and constructively or destructively interfere with other AC signals. In fact in most power system the base AC signal is a superposition of three si... | [
"In fact in most power system the base AC signal is a superposition of three sinusoidal AC signals all offset in phase by 120 degrees from one another.",
"No it's not, the three phases are sent on different wires.",
"Three sinusoids, offset in 120 degree increments, would completely cancel if combined via super... | [
"Well, each sine wave starts on a separate wire, but they all cancel out on the shared neutral, so there's minimal load over that line assuming a balanced load; otherwise you'd need a need a neutral line 3x the capacity of each hot line."
] |
[
"How do we know the mass of quarks when it is impossible to separate them from each other and not knowing the binding energy?"
] | [
false
] | null | [
"The particle data group has a section on ",
"quark masses",
". This is a notorious problem, both conceptually and experimentally.",
"Defining and evaluating quark masses is most challenging for light quarks. The basic idea is to find ways to relate observed hadron masses, and the differences and ratios there... | [
"We can picture a proton as 3 valence quarks (up, up, and down) switching their respective colors by exchanging gluons between one another. These gluons can in turn themselves split into quark-antiquark pairs, and can even radiate gluons. The process repeats, and the extents of this process depends on the scale of ... | [
"For heavy quarks (charm, bottom) the hadron mass is dominated by the heavy quark so it is relatively easy.",
"The top quark decays before it hadronizes, here we can actually measure its mass directly.",
"See the other comment for the light quarks."
] |
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