title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How do giraffes breathe?"
] | [
false
] | Basically, the text. The giraffe neck is around 6 feet long, so how do they generate enough pressure for air to travel six feet and also relatively fast? How do they remove air and prevent too much physiological dead space? | [
"Long neck, but narrow; massive lungs, 8x the size of a human's; a strong heart that gives it blood pressure twice that of a human's; and a respiration rate 1/3 as slow as a human's.",
"Essentially: their throat will fill with dead air; it's too big not to. But, their lungs are huge, and they have a respiration r... | [
"I would imagine the main reason for their higher blood pressure is so blood is able to reach their heads, you need roughly 23mmHg per foot in height."
] | [
"yup, iirc, their skin is super tight around their legs to help get that blood to easily shoot up the neck."
] |
[
"Does the brain go through any physiological changes when the person is in coma? And are there any differences between medically induced coma?"
] | [
false
] | null | [
"That's an interesting question, and the answer will depend on several factors. ",
"One way to look at it is comas are altered states of consciousness, brought about by various onsets. The cause of the coma will often contribute to observable brain changes. For example, if someone has an infection in the brain, i... | [
"This is a difficult question to answer without knowing more specifics about exactly what you're trying to ask. ",
"But overall, there are, of course, physiological processes happening during a coma. This is a really complicated topic, but in simpler terms, a coma is the worst condition of what are known as \"dis... | [
"A coma allows the body/brain to heal more effectively because the brain has shut down many functions.",
"The difference between a coma and a medically-induced coma just comes down to how the coma is introduced to the body/brain. If you get a head injury and your brain shuts down by itself there is no way to kno... |
[
"Mass of the universe right after the Big Bang - why all this condensed mass not create a black hole?"
] | [
false
] | Assuming the mass of the universe right after the Big Bang was equal to today's mass.... so much mass in such a small area, why was there no immediate black hole formation? | [
"The universe was still infinitely big immediately after the big bang, just much much more dense. The universe was also ",
" uniform and ",
" hot. Because it was uniform, the gravitational acceleration on any point is basically zero. There were tiny fluctuations in density, but the universe was so hot that its ... | [
"Hot in the normal sense of very very high temperature :)",
"As the universe expanded, the energy just spread out more."
] | [
"Hot in the normal sense of very very high temperature :)",
"As the universe expanded, the energy just spread out more."
] |
[
"Why do planetary rings form in a plane instead of a shell?"
] | [
false
] | null | [
"Orbital dynamicist here. You're essentially correct. It's the same reason why solid particles in the nebula settled into a plane. I don't think it has to be collisional to work, repeated gravitational interactions would work too. Note that the origin of the rings is still an open question. Them coming from a rippe... | [
"I'm certainly not an expert but I'm not sure this is correct. I believe It's true that rings are usually cause by the gravity of the planet ripping apart the moon along it's orbital plane and so the debris spreads apart in the up direction (relative to the planet) instead of the north south direction. However tha... | [
"It's because the whole system is rotating, and rotating things tend to bulge at the equator. That's why the Earth is thicker at the equator than pole-to-pole, and why all the planets orbit in more-or-less the same plane.",
"See below for a better explanation"
] |
[
"Walking barefoot in the library at my college, I was just told by a janitor that I shouldn't do that because of all the chemicals they spray on the floor (to remove stains, etc.). In truth, how susceptible are my bare feet?"
] | [
false
] | This is a from . Thank you very much. Edit: for those arguing about athlete's foot and other fungus... I actually do have athlete's foot toe fungus on all of my toe nails. It seems to be going away now that I've been going bare foot much more. I've been barefoot most of the time since May. | [
"Janitor here so I can tell you that it depends on the chemical being used. If he told you not to do it though he's probably right. Most janitors are trained in at least some basic hazardous materials handling because we tend to have at least one or two chemicals we have to use on occasion that can fuck you up. ",
... | [
"Come on, this is a SCIENCE reddit. People who walk around barefoot in the library simply do not ever get fungal infections. The problems arise when you go someplace where a bunch of people who normally wear shoes all take off their shoes and walk around on wet floors. The real key is people who wear occlusive shoe... | [
"No, you didn't."
] |
[
"Why does water seem colder after you chew mint gum?"
] | [
false
] | Edit: first kind of popular post! Thanks for knowledge!! | [
"Your \"cold\" sensation is reported via an ion channel called ",
"TRPM8",
". Lower temperatures trigger that channel, which reports to your brain that something is cold. However, menthol ",
" triggers that channel, giving you a sensation of coldness.",
"When you take a sip of water after chewing the gum, y... | [
"Capsaicin (the chemical in spicy food) activates the TRPV1 channel, which also senses heat. Both TRPV1 and TRPM8 belong to a larger family of ion channels called TRP (transient receptor potential) channels."
] | [
"Do you know of any other substances that \"short-circuit\" our senses in a similar way? "
] |
[
"What stops hair getting stuck in healing wounds?"
] | [
false
] | I recently found myself with reason to worry about this, but it turned out not to be a problem... how come? It certainly makes getting the scab off a pain, though. | [
"More of origin. If you were worried about contamination from external sources that'd be different than worrying about hair on your body. ",
"As for leg hair, I don't know. Piloerector muscles around the hair follicles may play a role to pull it loose, or the wound could just shove things out of it as it heals... | [
"What kind of hair? Arm hair? "
] | [
"Well in this case, leg hair. What's the difference?"
] |
[
"What is heat?"
] | [
false
] | [deleted] | [
"Temperature is, in macro world, the manifestation of particles' mean velocity.",
"Heat makes things (particles) move faster because, either by mixing or by heating up from a plate, we introduce higher-velocity particles into the mixture. When it's mixing, the particles from two different substances mutually exch... | [
"Heat is energy transfer as a result of a temperature difference. ",
" is the manifestation of particles' mean velocity. "
] | [
"A good rule of thumb is that it's the energy of ",
" motion. A whole mess of particles traveling in the same direction don't have \"heat\" per se. But when particles are all travelling in random directions, their average motions balance out to zero."
] |
[
"What happens to your muscle when you sprain it?"
] | [
false
] | null | [
"A sprain actually doesn't involve any damage within the muscle tissue. A sprain affects the ligaments that connect bones to joints and can vary from a snapped ligament down to just a ligament that has a twist. What I believe you're thinking of is a strain and the easiest way to understand that is to look at a pict... | [
"Ligaments are connective tissue connecting bones to bone, and tendons connect muscle to bone. You sprain a ligament, strain a muscle. Straining a muscle involves tearing the elastic fibers, similar to what's written above. Just specifying a little! "
] | [
"Also a strain. The words are different so that it gives medical providers a much quicker understanding of what structures are actually injured. "
] |
[
"How noisy is it on the surface of the sun?"
] | [
false
] | Is it the loudest place in our system? | [
"The surface of the sun is considered to be the tau=1 line of 5000A. In easy to explain terms, it is what you see if you look at the Sun in visible light.",
"It is basically where the convective zone ends. Above that is considered to be the Solar Atmosphere."
] | [
"In fact we can, and we do!",
"Sound waves propagate through all phases of mater: solids, liquids, gases, and plasmas. The energy contained in these waves is a measure of \"how noisy\" it is. ",
"Solar scientist use the propagation of sound waves in the sun to study its interior (helioseismology), just like geo... | [
"So going of off ",
"u/Jellyman87",
" numbers (150dB on earth, sun 149,600,000km from earth) I did some quick searches and whatnot.",
"Using this formula; ",
"Lp2 = 20 log (R2 / R1) + Lp1",
" with this input; 20log((1/149,600,000,000))+150, I got that the surface of the sun would experience ",
".. Whic... |
[
"Do astronauts come back from space with weak immune systems?"
] | [
false
] | Being encapsulated in an artificial place for so long and not being exposed to the amount of bacteria and viruses that exist on earth can weaken one's immune system over time, correct? | [
"Believe it or not, ",
"Auerbach's textbook of wilderness medicine",
" has an entire chapter on space medicine. ",
"Here are the bullet points on the effects of microgravity on the immune system"
] | [
"On a similar note, how about seamen on a submarine that is basically encapsulated for months on end beneath the water?"
] | [
"While the following is speculation, I offer this article geared towards the layman as compensation.",
"http://www.navy.mil/navydata/cno/n87/usw/issue_31/idc.html",
"The air on a submarine has to be scrubbed of CO2 while underwater, and I presume a certain amount of purification is performed. That said a subma... |
[
"If a nuclear apocalypse were to happen, and every single nuclear weapon in the world was used, how long would it take for the accumulating fallout to decay and make the surface habitable?"
] | [
false
] | null | [
"It all depends on what one means by \"habitable.\" You can, for example, still go live near Chernobyl (some people do, and many people work on the site still). It just will expose you to a chronic, low amount of radioactivity, and that will increase the chances of cancer or birth defects in whatever population is ... | [
"I don't think it would necessarily be that cut and dry if per OP's inquiry every currently functional nuclear weapon in the world were to detonate in a nuclear exchange. Consider for example the scenario where a nuclear detonation coincided with a severe weather system such as a tropical cyclone (as we're headed i... | [
"significantly revised some of the original data that were presumably used to carry out those calculations and simulations?",
"It's not that significant a revision from a damage perspective. They are saying, \"oh, this thing we had judged to be 100 kilotons was really 110 kilotons.\" That sort of thing. From a wa... |
[
"Surnames appear to be \"lost\" with each generation of humans (typically through marriage or lack of procreation). Is the pool of last names slowly shrinking over time? Are we converging to a small subset of last names?"
] | [
false
] | It seems to me that the number of unique last names, over time, will eventually dwindle down to a smaller set of what exists today. When I list the things that "create" surnames vs. things that "eliminate" surnames, the former list seems much smaller than the latter. Things that "create" last names: Things that "eliminate" last names: Could this be a real phenomenon? Is this only a problem in Western culture - are other cultures generating new surnames with their customs? | [
"Yep, it's a known and studied process with it's own name--the Galton-Watson process.",
"The best documented example is from China, where family names have been used for a long time. 12000 names are known from the historical record, but only 3100 are in use today. ",
"http://en.wikipedia.org/wiki/Extinction_o... | [
"Wow, I had no idea this phenomenon has a name, much less so studied. Thank you very much!"
] | [
"All together, the top hundred surnames account for 84.77% of China's population. By way of comparison, in the United States the top 100 surnames account for only 16.4% of the population, and reaching 89.8% of the US population required more than 150,000 surnames. ",
"https://en.wikipedia.org/wiki/List_of_common... |
[
"Why can't we just \"bleed out\" lead poisoning victims who can't afford the full treatment?"
] | [
false
] | I'm sure I must be missing something really obvious here, but I keep hearing about kids in underdeveloped countries who are dying from lead poisoning because they couldn't afford treatment. but since lead poisoning is just dangerous concentrations of Pb in blood, couldn't a cheap form of treatment be to bleed out the patient a little bit every ~2 months or so, just enough to keep them healthy? Wouldn't the volume of blood eventually be restored between each procedure, thus increasing the ratio of "pure" blood to contaminated blood and decreasing lead concentrations? Or is the lead not actually in the blood, but absorbed by organic tissue? | [
"Its toxicity comes from being absorbed by normal tissue, not just the amount that's free in the blood. Most of how they treat it is chelation therapy, where you give people chemicals that bind to lead, and then they excrete it. Also, bleeding people is a bad idea when one of the main symptoms of lead poisoning i... | [
"Lead does bind to soft-tissues and bone, in addition to circulating in the blood. Also, lead that remains in the blood already has a half-life measured in weeks, which means that blood-letting could not safely accelerate this process in a meaningful way. "
] | [
"This is more a complicated question than what others have tried to answer.",
"For example, \"bleeding out\" chronic iron poisoning patients works. And is in fact used in some situations as opposed to just using chelation. This works despite the fact that the problems with iron toxicity relate to it being absorbe... |
[
"Why is the EM drive \"impossible\"?"
] | [
false
] | null | [
"In what way does it violate the law of conservation of momentum? I'm a chemist not a physicist so it's a bit hard for me to understand. "
] | [
"In what way does it violate the law of conservation of momentum? I'm a chemist not a physicist so it's a bit hard for me to understand. "
] | [
"So it doesn't matter that the energy of momentum is cancelled by the energy lost from the EM wave if it's not pushing against anything (according to current laws of physics)?"
] |
[
"If I walked out of a spaceship naked, into the near vacuum of space, would I be hot or cold?"
] | [
false
] | The breathing on Mars question made me curious. The vacuum of space is an insulator. Is it enough of an insulator to cause me to overheat? Or would I freeze? | [
"It would depend on if there was another heat source besides your body. Tests with animals have shown that when exposed to vacuum their fluids immediately evaporate and form thin layers of frost (water freezes at about -70C in near vacuum). A person being thrust into a vacuum situation would have this thin layer of... | [
"NASA used to have a very good FAQ page about this stuff but it is gone. Here is one of their ",
"pages",
" referencing the astronaut incident. ",
"This",
" is a second hand reference to animals' fluids freezing. The studies they have done on animals don't seem too easy to find online but they are reference... | [
"Are you exposed to sunlight or shielded from it by a shadow? In a vacuum the temperature difference between lit and shaded sides can get very extreme."
] |
[
"As far as we know, is matter continuous or discrete?"
] | [
false
] | [deleted] | [
"There is a theorised smallest length, called the \"planck length\". In short, it's the absolute minimum length that it is theoretically possible to measure, regardless of how good our measuring technology becomes. I've heard it referred to as the \"pixel size of the universe\", which seems fitting if it truly is t... | [
"The Planck length is the hypothesized length scale of quantum gravity. This is very different from being the smallest length possible. For example, the length scale of an electron in an orbital about an atom is around an angstrom, but that doesn't mean it's the smallest length possible, merely that nothing very ... | [
"Thus I believe my assertion that this is the smallest length is justified?",
"No it isn't, it's the equivalent of you saying \"I can't see beyond the horizon, so nothing beyond the horizon is physically meaningful.\""
] |
[
"Is it possible there are dinosaur bone fragments on the moon due to the Chicxulub impact?"
] | [
false
] | We have rock here in the form of meteorites so I thought that it might be possible for something go have made it into space from the impact here on earth. | [
"Dinosaur vapor maybe.",
"Throwing something out of the atmosphere at escape velocity is hard. ",
"You totally can",
" and it is faintly possible Earth's microbes might even have made it to other places in the solar system inside a rock. ",
"Flaming dinosaur chunks could follow a similar trajectory, but org... | [
"Indeed. It would however still have to contend with the intense metamorphism and shock due to the initial and terminal impacts implicit in the process. Even the original mineralogy does not necessarily survive that. Fossils would'nt fare much better."
] | [
"Indeed. It would however still have to contend with the intense metamorphism and shock due to the initial and terminal impacts implicit in the process. Even the original mineralogy does not necessarily survive that. Fossils would'nt fare much better."
] |
[
"Can someone explain why there are so many variants of allergies to cats?"
] | [
false
] | I seem to be allergic to every cat, but invariably, people tell me "Oh, but this is a long-haired cat. My brother is allergic to most cats, but not long haired." Or, "Try to get a Siamese cat, no one is allergic to Siamese cats." Do people have different triggers for different cats, or are all my friends full of shit? I seem to be uniformly allergic to all cats. Thanks, Reddit! | [
"Since the most common allergens are produced in cat's saliva, cats who groom more should theoretically have more of the allergen in their dander.",
"I know from personal experience that I have a much worse reaction to my female cat who is a constant groomer (and also sheds quite a lot). My male cat grooms himsel... | [
"The main allergen of cats is called secretoglobin. It's a protein found in cat skin and saliva. The amount of the protein in different breeds varies, but still all cats have it. It really depends on the person how sensitive he/she is to the allergen and their combinations. Cats have total of 5 different allergens.... | [
"They're full of shit, as most people are."
] |
[
"Would the Superconducting Super Collider, that was cancelled have been a huge science gain over the LHC?"
] | [
false
] | I was wondering because of this post that brought up how it looks today: For those curious: | [
"It would have had about three times the energy: 40 TeV total vs 14. That means that it would have gotten the same results faster (look at how fast the LHC found what the Tevatron spent years looking for) and would have had a better chance at finding new physics like supersymmetry."
] | [
"With the issues the LHC has had so far, would those and others have only been magnified if we went forward with this beast?"
] | [
"Likely yes. The SSC would have been capable of a much more thorough test of the existence of the Higgs boson (among other things) than the LHC."
] |
[
"In stem cell therapies, how do doctors get stem cells to the tissue or organ they are attempting to repair? Are stems cells too large to be delivered through an injection?"
] | [
false
] | null | [
"Stem cells can be delivered via injection; however, that does not guarantee they’ll stay where you put them. For example, a relatively recently study in horses showed that the majority of stem cells they injected intra-articularly (into joints) ended up migrating to the lungs. "
] | [
"I'm not sure if technology has progressed to where we are actually growing new organs for people but it's extremely close. This is almost like a 3D printer but the blueprint is stem cells. ",
"If you're getting a stem cell transplant (also bone marrow transplant) for cancer basically first they kill your exist... | [
"Very interesting, thanks for the response. Do you have a link to that study? I'd be interested to check it out "
] |
[
"Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Please only answer a posted question if you are an expert in the field. . In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for . If you would like to become a member of the AskScience panel, . Past AskAnythingWednesday posts . Ask away! | [
"Well for example changing eye colour is possible in the current day, but not through DNA altercations... Most of those examples humans do through different means then what you're talking about (Self tanner, Hair dye, etc) Because the risks out weigh the costs of affecting those through DNA in adults... For excampl... | [
"Is there a way to use CRISPR/RNA editing on adults? and as someone who want's to go into gene editing/biotech area are there any online resources or communities you can recommend to further my studies right now?"
] | [
"CRISPR has actually started being used on adults with severe diseases in the US"
] |
[
"Why does ethanol evaporate out of my cleaning solutions or off the glass im cleaning but not out of my gin and tonic?"
] | [
false
] | null | [
"Well, it does in both cases. It's just a question of rate. ",
"Assuming ideal behaviour, ",
"Raoult's Law",
" says that the vapour pressure of substances in a mixed solvent system reflect their relative composition in the solvent. So the component that makes up more of the solvent will end up being more of t... | [
"In addition to what ",
"/u/superhelical",
" has said, there's one more thing to consider: surface area. When you wipe your window with cleaning solution, you're spreading a small volume of liquid over a large surface. There is now a much larger surface area to evaporate from, compared to the liquid surface in ... | [
"Ethanol-water deviates from Raoult's law because it is a ",
"positive azeotropic mixture",
". For an ethanol-water mixture, the vapor pressure of the mixture can be higher than either component alone. ",
"Water and alcohol make a positive azeotrope because they don't stick to each other as well as each one s... |
[
"For any given probability density function, is there an upper limit on the difference between median and mean in relation to the standard deviation?"
] | [
false
] | [deleted] | [
"Are you asking is there a bound on (mean-median)/sd ? That's bounded between -1 and 1.",
"See, for example,",
"O’Cinneide C.A. (1990),",
"\n\"The mean is within one standard deviation of any median.\"",
"\n",
" ",
", 292–293",
"(the basic result is considerably older)",
"With some additional inform... | [
"This requires the existence of a mean and standard deviation. PDFs needn't have them"
] | [
"and the standard deviation. Those are huge restrictions. Stable distributions can't violate both those requirements."
] |
[
"Please help with a thermocouple problem."
] | [
false
] | [deleted] | [
"If no one can help you here try ",
"/r/askscitech",
" or ",
"/r/beakers",
"."
] | [
"Type R or S might do the trick. That's just eyeballing off of these ",
"voltage-temperature curves",
".",
"Edit: And B might be worth looking into, though it isn't on that curve. It's also got a not-so-steep slope."
] | [
"Here is my suggestion: Find a user manual for the hot press. Find out what thermocouple its supposed to have. Then ",
"just buy a damn thermocouple.",
" They're cheap, a hell of a lot cheaper than buying a new piece of equipment because the temperature controller didn't work properly because it was connected t... |
[
"What would be the consequences of a global, significant and sustained population decrease on the economy?"
] | [
false
] | Would it necessarily imply economic collapse? Deflation? Can economic growth be possible in such conditions; if so how? | [
"The problems arise when the population has more older people than younger people, as it poses significant challenges to social programs and other societal institutions that depend upon a relatively large workforce to be sustainable. There are already countries facing this issue right now, like Japan, which sells m... | [
"The key issue would be a decrease in the percentage of the population capable of (efficiently) performing labour.",
"It varies from person to person, but between 50 and 80 a large majority of people become unable to perform physical labour and an increasing number become less capable of performing other work.",
... | [
"That's a very likely possibility. A significant decrease in Earth's population would affect a variety of factors for both businesses and consumers. Less people means less need for supply and demand, fewer people would start businesses, reducing competition in the marketplace, less drive to innovate...the effects w... |
[
"Living and traveling all around the US, I've heard lots of stories about invasive species of plants, fish, insects, etc. wreaking havoc on the local enviornment. Are the examples of American flora/fauna invading other countries?"
] | [
false
] | null | [
"Yes.",
"UK. Grey Squirrels are an invasive species that have largely driven out our smaller, but much, much cuter, red squirrels.",
"Others from the US are: the American Bullfrog, American Mink, Floating Pennywort, American Skunk Cabbage, Raccoon, Pitcher Plant, and Signal Crayfish.",
"And those are just the... | [
"They dont grow particularly aggressively where I live in New England",
"That's the thing. They've been there so long everything else has adapted and eats or competes with it, or has learnt to avoid it... Point is, they adapted along side it. ",
"But bring it somewhere else and nothing knows what to do with it.... | [
"Oh, absolutely. There are several invasive American insects, for example.",
"The Colorado potato beetle is particularly notable for having being a destructive pest in America first. It originally fed on buffalo bur, a native American ",
" species (this is a large plant genus that also includes potatoes, tomato... |
[
"Why do humans have to brush their teeth in order to keep it healthy while most (all?) animal naturally have good teeth?"
] | [
false
] | null | [
"Animals do not have any better dental health than us. Most animals die before they get old enough to have serious dental disease, or the dental disease it self kills them. ",
"80% of cats and dogs will have some form of dental disease by 5 years of age (stat from my professor in vet school). They don't get cavit... | [
"I'm quite sure that I would die of bleeding if I were to try to brush my cats teeth every night.",
"Is there something you can do instead? Chewing toys or special kinds of food or stuff like that?"
] | [
"From a human end, we don't have a lot of antibacterial components to our saliva. Also, we eat a lot of processed foods with simple carbohydrates (read sucrose) in them. These case acidogenic bacteria to produce acid and demineralize tooth structure. This demineralization over time causes cavities (a disease cal... |
[
"Do cell organelles float freely in the cytoplasm? Or are they attached to the cell membrane/some other structure through microtubules?"
] | [
false
] | null | [
"For the most part, they're anchored directly or indirectly to intermediate filaments (IFs), which are part of a eukaryotic cell's cytoskeleton. This tethering may involve microtubules. As far as your question on free-floating organelles is concerned, there is a scaffold-mediated internal architecture to the cell... | [
"just as a visual aid, here is a picture of an endothelial cell with the keratin (just one type of IFs) stained:",
"http://www.microscopyu.com/articles/fluorescence/filtercubes/yfp/yfphyq/stains/images/yfpcy2keratinptk2cells.jpg"
] | [
"This is correct. Cells are actually highly structured and organized spaces. Most movement of organelles within the cell, for example, occurs on microtubule highways driven by ",
"motor proteins",
". "
] |
[
"Why did the atom in the video \"vanish\" instead of being gradually engulfed?"
] | [
false
] | null | [
"These are not two individual atoms of gold but nanoparticles with a diameter of about 25 nm from the looks of the larger one. The graniness of the bodies is actually the individual atoms. I have experience identifying latice plains in transmission electron microscopy.\nAs for your question. These particles seem... | [
"To add to this, the sample appears to be heated, which is why the gold nanoparticles are moving. Once the two particles make contact, the surface energy of the 'almost two particle' system is much higher than a single particle, and therefore the two quickly merge to form a lower energy shape"
] | [
"Hard to tell what's going on here. I can think of a couple possible explanations. One is that for whatever reason that atom or collection of atoms popped out of the focal plane. But since the other agglomeration appears to get bigger after the smaller one disappears, I think what's more likely is that the two grou... |
[
"E of a photon is proportionnal to frequency. As energy can't be infinite, does that mean frequency have a maximum value ?"
] | [
false
] | null | [
"There is no maximum energy or frequency for a photon."
] | [
"Why ? Does'nt infinite energy break physics laws ?"
] | [
"The energy is always finite, but there is no maximum."
] |
[
"What's going on with the Novel Langya Henipavirus that's in the news currently? I have a few questions."
] | [
false
] | I have a few questions about this virus because these news articles don't make it too clear: | [
"Can’t really help you with the first 2 questions, about Number 3, there is a possibility that this virus get airbourne transmisión. If not, there may be, for different reasons, a higher number of infected animals (in this case, bats, or a number of other possible natural reservoirs ) that may transmit the virus to... | [
"Do not apologise, that's lovely information. Thank you."
] | [
"Articles say human to human transmission hasn't been identified. How did 35 people presumably get the same virus?",
"This isn’t at all surprising, for a couple of different reasons. Firstly, it is really hard to prove human-to-human transmission - you might recall the very early stages of the COVID-19 pandemic, ... |
[
"Would it be possible to induce the feeling of hunger in someone who had a full stomach simply by putting certain hormones, etc into their bloodstream?"
] | [
false
] | null | [
"While it's always a bit more complicated than simply putting certain hormones into their bloodstream, yes, it's very possible. Your body uses several hormones to regulate food intake and satiety:\nLeptin: Produced by fat (adipose) tissue, increase satiety by binding to Neuropeptide Y neurons in the hypothalamus\nN... | [
"using marijuana simply ",
" the munchies counteracts nausea."
] | [
"nausea makes you not want to eat. marijuana makes you want to eat. what do you think?"
] |
[
"Why are earth years used when referring to the age of things that existed before planet earth existed?"
] | [
false
] | null | [
"It's just a unit of time. It's easier for humans to understand what \"one year\" means. One year is defined exactly as 31,557,600 and that definition is valid regardless of whether humans or Earth exist."
] | [
"Because years are a unit of time that humans understand and these numbers are used by humans to communicate to other humans."
] | [
"It seems strange to me that it's used when referring to the existence of other things that are much older than the earth itself."
] |
[
"What is water tension? And do other liquids have the same property?"
] | [
false
] | I may have already been taught this way back when, when I used to do Chemistry, but have completely forgotten. Is it something to do with the molecular structure of water or is this a property found in every/many liquids? Thanks x | [
"All molecules have surface tension. Basically it's a result of the fact that molecules in a liquid attract more strongly than molecules in a gas. So at the surface of the liquid, where the two meet, there's more attraction from the liquid side than from the gas side. "
] | [
"I'd like to add that water experiences a much more noticeable surface tension due to increased intermolecular forces, namely dipole-dipole and hydrogen bonding. Due to water's rare ability to hydrogen bond with itself, it has one of the highest cohesion forces of any non-metallic liquid."
] | [
"Water tension, and other surface tensions are created by ",
"Intermolecular Forces",
". These forces, are basically a small amount of attraction between the molecules that brings them closer and resist separation. These happen between molecules, and the bonds' strength depends on the structure and atoms within... |
[
"What causes that squeaky noise when you rub a wet finger over a mirror or other smooth surface?"
] | [
false
] | why doesn't it work with a dry finger? | [
"There's two scenarios at play here: one where your finger is touching the surface, and the other where it's touching water. The surface has a higher coefficient of static friction, meaning it will do a decent job of keeping the finger in place despite other forces (it's sticky). The water, on the other hand, has a... | [
"BlazeOrange gave a good response, but there's a name for what this phenomenon is called. ",
"Schallamach waves",
" occur when an elastomer (or springy substance like the skin on your finger) is rubbed across a smooth surface with high ",
"surface energy",
". Waves of contact and separation occur across t... | [
"I really would like the know a complete answer for this but i have some input that i think might be a reason.",
"possibly something to do with the glass being to smooth? and the water rubbing up against such a smooth surface?",
"im not sure man! but id love to find out!"
] |
[
"AskScience AMA Series: I’m Stephan Lewandowsky, here with Klaus Oberauer, we will be responding to your questions about the conflict between our brains and our globe: How will we meet the challenges of the 21st century despite our cognitive limitations? AMA!"
] | [
false
] | Hi, I am Stephan Lewandowsky. I am a Professor of Cognitive Psychology at the University of Bristol. I am also affiliated with the Cabot Institute at the University of Bristol, which is an inter-disciplinary research center dedicated to exploring the challenges of living with environmental uncertainty. I received my undergraduate degree from Washington College (Chestertown, MD), and a Masters and PhD from the University of Toronto. I served on the Faculty at the University of Oklahoma from 1990 to 1995 before moving to Australia, where I was a Professor at the University of Western Australia until two years ago. I’ve published more than 150 peer-reviewed journal articles, chapters, and books. I have been fascinated by several questions during my career, but most recently I have been working on issues arising out of the apparent conflict between two complex systems, namely the limitations of our human cognitive apparatus and the structure of the Earth’s climate system. I have been particularly interested in two aspects of this apparent conflict: One that arises from the opposition of some people to the findings of climate science, which has led to the dissemination of much disinformation, and one that arises from people’s inability to understand the consequences of scientific uncertainty surrounding climate change. I have applied my research to both issues, which has resulted in various scholarly publications and two public “handbooks”. The first handbook summarized the literature on how to debunk misinformation and was written by John Cook and myself and can be found here: . The second handbook on “communicating and dealing with uncertainty” was written by Adam Corner, with me and two other colleagues as co-authors, and it appeared earlier this month. It can be found here: . I have also recently published 4 papers that show that denial of climate science is often associated with an element of conspiratorial thinking or discourse (three of those were with Klaus Oberauer as co-author). U.S. Senator Inhofe has been seeking confirmation for my findings by writing a book entitled “The Greatest Hoax: How the global warming conspiracy threatens your future.” I am Klaus Oberauer. I am Professor of Cognitive Psychology at University of Zurich. I am interested in how human intelligence works, and why it is limited: To what degree is our reasoning and behavior rational, and what are the limits to our rationality? I am also interested in the Philosophy of Mind (e.g., what is consciousness, what does it mean to have a mental representation?) I studied psychology at the Free University Berlin and received my PhD from University of Heidelberg. I’ve worked at Universities of Mannheim, Potsdam, and Bristol before moving to Zurich in 2009. With my team in Zurich I run experiments testing the limits of people’s cognitive abilities, and I run computer simulations trying to make the algorithms behave as smart, and as dumb, as real people. We look forward to answering your question about psychology, cognition, uncertainty in climate science, and the politics surrounding all that. Ask us almost anything! : We spent another hour this morning responding to some comments, but we now have to wind things down and resume our day jobs. Fortunately, SL's day job includes being Digital Content Editor for the Psychonomic Society which means he blogs on matters relating to cognition and how the mind works here: . Feel free to continue the discussion there. | [
"I don't think so, because progress in science usually involves simplification. For instance, astronomer's knowledge about the movement of celestial bodies before Kopernikus was much more complicated than after that. By simplifying our knowledge we can teach it more efficiently, freeing our capacity to work on the ... | [
"Just posted this in the Stephen Hawking AMA, but then saw the title of yours and said: Hey. I should post that there. So here it is: ",
"This was a question proposed by one of my students: ",
"Then follow-ups to that:",
"if not, why not?",
"if we do, how far in the future do you think that might be, and wh... | [
"That's a very hard question - essentially it is about how to distinguish reliable information from propaganda, given that the propagandists (for various causes, from ideologies and religions to corporate profit) are often very skilled at pretending to have all the features that characterize reliable information. O... |
[
"Can you please explain the approach orbit for Rosetta to the comet it is landing on on Jan 20? (Link, Video inside)"
] | [
false
] | Seen here: and directly on YouTube here The spacecraft approaches in this weird triangular orbit with almost-straight lines. I assume there's a burn at each of these points but that is a lot of changing direction for I'm not sure what purpose. Do you think it's needed for 3D imaging the comet as much as possible? | [
"The video you posted is a stylized representation of Rosetta's approach of the comet. That type of video is meant to provide a sense of the mission without providing real numbers or sense of time or scale. Some annotation would have been nice.\nSimilarly, this video shows the craft's journey from earth to the come... | [
"Based on the ",
"mission profile",
" it appears that you're right that it is for imaging the comet. Primarily for the purposes of finding a safe way to approach the comet through the debris and then to find a suitable landing site."
] | [
"One other thing to keep in mind, this is not like orbiting a planet. The gravitational pull is minuscule in comparison. Instead, think of this as drifting back and forth along the line of advance of the comet. The directional changes are not going to require a lot of energy."
] |
[
"Are there any society-wide (epidemiological) consequences to the widespread use of flu vaccines?"
] | [
false
] | I was curious if there was any mechanism with vaccines similar to the "antibiotics -> super-bug" issue. I found but I was curious if there were any other issues that epidemiologist-types watch out for. I've read a handful of studies and articles enough to have a decent understanding of vaccines on a local/individual level, but couldn't find anything [reputable] that really addressed my question. I was specifically looking at flu vaccines since their target changes so rapidly, but I would imagine any vaccine going after a "moving target" would be the same. As a related follow-up, is it possible for a society (not an individual) to overuse a vaccine? Or is it basically a (pardon the over-simplification) "magic-bullet"? | [
"The epidemiological consequence of widespread use of flu vaccines would be a widespread drop in flu infection rates =) There is no (reputable) evidence that widespread use of vaccines have any significant downside (standard caveats about exceptional or rare side cases apply). As the thread you linked pointed out... | [
"Usually, when a vaccine works, the pathogen is eliminated, and doesn't have a chance to survive, therefore it doesn't have a chance to adapt and evolve new mechanisms of survival.\nSo, that's why you don't see things like \"Super Polio\" popping up, because some vaccines pretty much work very effectively, in some ... | [
"Not surprisingly, lots of viruses (as well as other types of pathogens) use the strategy of \"I'm going to rapidly mutate/shift my surface proteins to evade an immune response\" because, well, it's a damned effective way of evading an immune response!",
" comes to mind as far as antigen shedding/shifting pathoge... |
[
"What is the mathematical proof of the lift equation used to determine the lift produced by an aerofoil?"
] | [
false
] | The lift equation is L=Cl A 1/2 ρ v I understand why lift is produced by an aerofoil, I was wondering the proof behind it. I originally thought that Bernoulli's equation 1/2 ρ v = K-P However the closest I have got to is A 1/2 ρ v =K-P Is there a way to derive the lift equation without calculus? Or if there isn't, how would you prove the equation? | [
"The 'Cl' is determined experimentally, and encapsulates a lot of physics regarding, for example, the shape of the wing; it's not possible to derive the specific lift equation that includes the 'Cl' without more information. On the other hand we can easily argue that the form of the lift equation is correct. It is ... | [
"Well since Cl is a constant (depending on AoA) couldn't you assume that K=Cl and derive the equation from there?"
] | [
"What is K? In any case, if you assume a constant AoA, and absorb any constants in Cl, then the argument above works fine."
] |
[
"In humans, what happens to the majority of platelets after absorption by the spleen?"
] | [
false
] | I know that the spleen stores some platelets for release during a need, but surely they can't just build up in there forever? Are they broken down? If so, how? I haven't found any clear information on this. | [
"Platelets are phagocytosed (basically, \"eaten\") by macrophages in the spleen. I'm not sure what happens to those macrophages at the end of their life cycle. I'll look into it and post here if I find a good answer. "
] | [
"No, macrophages are white blood cells that act as scavengers, consuming and destroying bacteria and cellular debris through phagocytosis. Macrophages are several times bigger than red blood cells, whose sole purpose is to carry oxygen from the lungs to the tissues and CO2 back from the tissues to the lungs.",
"P... | [
"Macrophages also do the same, or similar, to erythrocytes, correct?",
"Thanks for the answer!"
] |
[
"If a planet is tidally locked around its parent star, then is it impossible for it to have moons?"
] | [
false
] | null | [
"Depends on the Lagrange point :)",
"L1, L2 & L3 are unstable, even though they are equilibrium points. So if a small planet was placed interior to our orbit at the L1 point, it'd eventually float away. You don't find natural astronomical objects at unstable points.",
"However, L4 & L5 are stable. These are the... | [
"Related question: How plausible would it be to have a moon that just sits at a Lagrange point?"
] | [
"I have heard you can increase the L1, L2 & L3 points stability by having an object orbit around the point as opposed to sitting in the point. I am not sure about the dynamics of it. Is there an upper limit as to how large an object you can do that with? Or, does it require some amount of energy to maintain the ... |
[
"Are \"core memories\" a real thing?"
] | [
false
] | Hey guys! I was recently thinking about the movie Inside Out, and more specifically "core memories". If you don't know, in the movie core memories are basically super important memories that help define your sense of self. So if you really like basketball, your first game may be a "core memory". You also only have a very small handful of them (<10). Now I'm not expecting a Pixar movie to have 100% accurate neurology, but are there any general concepts that are analogous to "core memories" in Inside Out? Are core memories, in any real sense, an actual thing? | [
"No, not a thing. As you describe them, these \"core\" memories would be part of autobiographical memory (memory about oneself). But there is no limited number of particularly special autobiographical memories that define people typically. A possible exception is a highly traumatic event.",
"Another slightly simi... | [
"It's more analogous to something you cherish than any real concept.",
"In real life, you may remember your first game of basketball, or you may not remember something of the sort until you win a big championship game. But there's no biological or emotional guarantee that you'll remember it any better than any ot... | [
"Thank you for the response!"
] |
[
"r/askscience, how feasible is it to \"do\" math research independently (no mentor, all by myself) and be able to publish in a journal, etc?"
] | [
false
] | Hi all, I"ll start with some background info. I've been working in a lab throughout college where the research focus is on brain cancer (Glioblastoma multiforme, to be precise). Our lab has a heavy molecular biology bent, so there's essentially no physicial or formal mathematical work done. The eventual plan is medical school but I'm planning on practicing Academic Medicine, so research is always something I'm planning on staying involved in. However, mathematics is a field that has always interested me and I'm motivated to learn/understand it better (particularly Topology). Moreover, I'd like to eventually try my hand at tackling some research problems (at least to the best of my ability). I'm wary of going to a mentor because of my pre-existing lab commitments, and along with everything else, I was intending on making my math studies an weekday evening/weekend type of venture. I feel like it'd be unreasonable of me to expect a mentor to take me on with those inconvenient hours. My question to all of you is, can I do research independently? And in the very very slight chance that I come up with something publication worthy.....do I stand a chance and submitting to a journal without a mentor? I'd welcome everyones thoughts/advice on this. Thank you :) P.S my mathematical qualifications (calc, diffeq, linear algebra). Obviously, before I undertake this task, I'd be spending a good number of months self-studying everything. | [
"I have tried and failed."
] | [
"To be honest, it'll be extremely extremely difficult, and self-studying and working probably won't work. If your math level is similar to mine (lower division undergrad calc/dif eq/linear algebra), than I would imagine it would take years before you could understand enough math to even realize what research proble... | [
"Mathematics at the university level is very collaborative. Researchers in a university department will talk to their colleagues in their department and at other universities. They will attend conferences and talks and read the latest journals, all in an effort to stay up to date.",
"A research student working ... |
[
"Would a human born on mars be stronger on mars than an earthling is on earth?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"For more information regarding this and similar issues, please see our ",
"guidelines.",
"/r/AskScienceDiscussion",
"Please see our ",
"guidelines.",
"If you disagree with this decision, pleas... | [
"Earth actually has a stronger gravitational force, so someone born on Mars and accustomed to Martian gravity would be ",
" than someone born on Earth and accustomed to our gravity. ",
"So your muscles have to work harder on Earth than on Mars, meaning they become stronger on Earth"
] | [
"Yes, I know earthlings would be able to exert a greater force than martians, but could they lift the same mass in an environment with 3 times as much gravity as the martian has to lift in?"
] |
[
"Does water count as boson, since it has even number of baryons and electrons?"
] | [
false
] | I've read somewhere that a boson is any particle with integer spin. And alpha particle is a boson too because it consists of an even number of fermions (in this case, proton and neutron). So if any composite particle consists of even number of fermions, shouldn't water molecule count as boson too? Normal water has one 16-Oxygen and two 1-Hydrogens, so the baryons (which are fermions) are even, and the electrons (fermions too) are even too. But there's nowhere said that water is a boson, so I must be wrong somewhere… | [
"Yes, a water molecule is a boson. It can have nuclear spin 0 or 1 (integers, you note). Ortho-water is water with spin 1 and para-water is water with spin 0. It's only quite recently we've been able to separate the two and find they have different chemical reactivity.",
"https://cosmosmagazine.com/science/chemis... | [
"An H",
"O molecule composed of hydrogen-1 and oxygen-16, with all of its electrons, is a boson."
] | [
"But there's nowhere said that water is a boson, so I must be wrong somewhere…",
"You'll have a hard time finding a situation where it would matter. Generally you need very cold temperatures for molecules, but water at cold temperatures forms ice where the crystal structure is more important."
] |
[
"Can I carbonate a beverage with helium?"
] | [
false
] | [deleted] | [
"You cannot \"carbonate\" a beverage with helium; ",
"carbonation",
" specifically refers to dissolving CO2 in a liquid. ",
"However you can ",
" gases other than CO2 in beverages to make them fizzy. One (fine) example is ",
"Guinness",
" beer, which contains mainly nitrogen gas (N2):",
"Draught Guinn... | [
"Wow that was really interesting! And a really well written answer! I had no idea Guiness was like that cause of Nitrogen. ",
"But to answer one of OPs other questions: no you wouldnt talk funny after drinking a drink with dissolved helium. You only talk funny because you inhale helium. Drinking it would mean its... | [
"While CO2 is indeed a natural product of fermentation, that does not mean that it is used to carbonate beverages. For fermented drinks (beer, wine) it depends on how the fermentation process was carried out and whether the bottling was done under pressure. For most beers sold, carbonation is achieved by directly a... |
[
"If I was standing on the surface of Europa, how bright would the day be, comparatively to earth? Would Jupiter's vastness in it's Horizon compensate in reflective lighting for the large distance away from the sun?"
] | [
false
] | [deleted] | [
"One thing that should be added to the pure astronomical calculation (1/5.2² = 3.6% of earth's illumination):",
"If only about 4% of the light hits your retina... it won't seem to you as if it is that dim. Our eyes perceive on a ",
" (minor quibbles possible). Our indoor lighting for example is ",
" dim compa... | [
"I suppose this explains why, during a recent solar eclipse I experienced in southern California, where the sun was basically down to a sliver, it was sort of disappointingly bright outside! I was hoping it would get really dark, but it didn't. "
] | [
"It did, but your pupils expanded to allow more light in. ",
"Imagine you were taking pictures with an SLR camera and manually adjusted the settings to be adequate for daylight before the eclipse. During the eclipse, you didn't adjust the aperture or exposure time at all and kept shooting. Your pictures during... |
[
"I understand how evolution selects for traits in a life-and-death sense, but what about for traits that have no bearing on whether the species lives or dies?"
] | [
false
] | [deleted] | [
"However, it seems like there are tons of traits that somehow are selected for and carry on, but have absolutely no bearing on whether a creature was more likely to survive, or more likely to reproduce.",
"One explanation of this phenomenon would be genetic pleiotropy, a mechanism in which one gene has a distinct... | [
"However, it seems like there are tons of traits that somehow are selected for and carry on, but have absolutely no bearing on whether a creature was more likely to survive, or more likely to reproduce.\nThere seem to be plenty of purely aesthetic traits that humans have",
"Don't confuse the fact that humans have... | [
"Here's an example of how non-selected traits may still be passed from generation to generation:",
"Let's take your example of butterfly eye patterns, where the patterns are under strong selection for some phenotype that we'll assume is produced by genotype. Now, being very clever molecular biologists, say we hav... |
[
"We know when the big bang happened; do we know where?"
] | [
false
] | null | [
" Hubble"
] | [
"the centre of the universe, where the big bang happened, is "
] | [
"If we do as you suggest, we would find that the centre of the universe is right here. The galaxies seem to be spreading away from us, and the further away galaxies are from us the faster they seem to be spreading away.",
"But, this isn't some special property of here, this is also true for every point in the uni... |
[
"What effects would someone without mental health issues feel from prolonged use of antipsychotic medication aimed towards the treatment of schizophrenia?"
] | [
false
] | null | [
"We know this pretty well, since antipsychotics are used for some patient groups who don’t have schizophrenia. They’re prescribed for depression, bipolar disorder, and others. Yes, these represent mental disorders. But really, the physiology of antipsychotic adverse effects is the same in almost everyone. ",
"Ant... | [
"I’m a psychiatrist.",
"While the issues related to movement disorders (tardive syndromes) mentioned by other responses are right, these are fairly benign side effects. By that I mean they are not life-threatening, but they are obviously not ideal since they can be quite pronounced and bothersome (interestingly, ... | [
"increased risk of death due to cardiovascular causes",
"Non-medical person here, but am very curious about this. In regards to increased risk of cardiovascular outcomes, if that's the case, then are these patients then also prescribed things like statins to counter the effects of the increased cardiovascular ris... |
[
"How do calculators/computers figure out how to display e or pi or the square root of 2? When you push the pi button on your calculator, what is it doing?"
] | [
false
] | null | [
"For pi and e, in all likelihood the calculator is simply recalling a constant it has stored which still leaves the question of sqrt(2) open. ",
"An important consideration is that digital devices cannot perform infinite precision arithmetic so when is comes to calculating the value of something like sqrt(2) what... | [
"I personally don't know which approach handheld calculators use if I'm to be honest, ",
"Early HP calculators, including the first handheld \"scientific\" calculator the HP-35, used CORDIC (which also computes trig functions).\nI'll leave out the gritty details, but it turns out that some basic arithmetic opera... | [
"General-purpose computers tend to use a lookup table and/or bit-fiddling tricks to get an initial approximation, followed by a few steps of Newton-Raphson or something similar to refine it to full precision. (I think this is just because the memory for the lookup table, and the circuitry for fast multiplies, is av... |
[
"Do Black Holes Precess as They Spin?"
] | [
false
] | Do black holes precess as they spin? Can the direction of their rotational axis change over time? I assume their angular momentum is the sum of the angular momentum of everything they have consumed, so if a black hole eats something new, its axis will change directions accordingly. But for a black hole with no external forces on it, is it possible to precess? If it is possible, does this mean that we could potentially see pulsing quasars? | [
"Hm, that's a very good question. ",
"I'd say no, they do not precess because they don't spin in the usual sense of the word. They do have angular momentum, but strictly speaking, there is nothing what actually can spin because that part of spacetime we call black holes is mostly vacuum.",
"Spacetime geometry o... | [
"It's really an interesting question. I mean, on the other hand, I'm a NMR guy, and we can sure model proton spin in an external field as precession, even though that is a classical approach that doesn't cover it fully. Wondering if something like it could go on here,"
] | [
"There's two types of precession. One is inherent to the object; this kind of precession a black hole cannot possess, because they are symmetric around the axis of rotation. However, precession caused by gravity (the same precession that the earth and the moon mostly experience) can happen for black holes."
] |
[
"In the double-slit experiment, wouldn't the act of observing the photographic plate, even after the fact, collapse the wave function?"
] | [
false
] | null | [
"I would reason that even the act of using a photographic plate would count as \"observation\"",
"You reason correctly. Yet this observation does not carry the information about which slit the photon travels through, so there is no conflict."
] | [
"Observation doesn't collapse the wavefunction, INTERACTION does. Despite what the pop-sci Youtube videos say, quantum mechanics has absolutely nothing to do with conscious observation."
] | [
"The photon hits the detector and the detector registers a \"hit.\" It gives you a position where a photon was detected. It has no information about which slit the photon came through."
] |
[
"What makes light reflecting off of a surface, change its color to that of the surface?"
] | [
false
] | As a photographer I often wonder why this is. I can bounce a strobe off of a colored surface, and the light will change to that color. Obviously not as strong or vibrant as the original surface color, but noticeably close. Additionally, what is happening when I shoot a strobe (flash) through an orange gel? The light becomes orange, is that due to certain light being filtered out, or does the gel act differently? | [
"Additionally, what is happening when I shoot a strobe (flash) through an orange gel? Is that due to certain light being filtered out?",
"Exactly, the material absorbs all colours except orange. The same goes for reflections - a red bowl absorbs all colours except red, which it reflects. Of course, nothing absorb... | [
"Thanks! I'm gonna get a prism and do that, sounds like a cool experiment. "
] | [
"Thanks! "
] |
[
"I need help finding out what this animal is."
] | [
false
] | I live in NW Pennsylvania and I found this leaf shaped, slug-like creature on a leaf in my back yard today. I really want to know what it is. I have took pictures of its back, underside, and *mouth. Please look at the pictures and tell me if you know what it is. * This picture is took under a microscope | [
"Can't offer advice, but I happened to see one in SE PA yesterday. Shape of it looks akin to a stink bug."
] | [
"It's not a stink bug because it doesn't have legs."
] | [
"No image. Bad link?"
] |
[
"Is it possible for a body of water (lake, pond, etc) to be naturally carbonated?"
] | [
false
] | null | [
"In fact, many bodies of water are naturally carbonated - they're called soda lakes. When you dissolve CO2 in water, you get carbonic acid which has a pKa of around 6.3. So when your body of water is sufficiently basic (pH>pKa1), carbonic acid will act as an acid and deprotonated to exist as bicarb. If your lake is... | [
"Speaking of taste buds, ",
"San Pellegrino",
" mineral water is bottled with naturally carbonated water."
] | [
"Lake Nyos",
" is an example of such a lake. It's an example of an \"exploding lake\" that can under some circumstances, degas rapidly as it did in 1986 which resulted in the asphixiation of almost 2,000 people."
] |
[
"Why don't antibiotics kill the good bacteria in our system?"
] | [
false
] | So, I know antibiotics are taken to kill bacterial infections, but how do they target only the bad, infecting bacteria and not kill the natural bacteria in our stomachs, intestines, etc. | [
"Actually, antibiotics ",
" kill the bacteria naturally found in your body. Antibiotic therapy is associated with overgrowth of ",
" gut flora in your bowels leading to intractable diarrhea.",
"When this occurs, it is recommended to ",
"change antibiotic therapy",
".",
"This is not a common occurrence,... | [
"They do actually, which is why abdominal pain, diarrhea, and things like that are listed under the side effects of just about every antibiotic on the market. But theres just a lot more of the good bacteria than any infectious bacteria so unless youre septic and on something really powerful like IV cipro for a long... | [
"Sometimes pathogenic bacteria and normal bacterial flora are the same thing. These are known as opportunistic pathogens.",
"\nYou should know that there are different classes of antibioticsc (",
") used to attack particular structures in bacteria that some have and some don't have (",
")",
"In short, antib... |
[
"Would we be able to tell if a planet millions of light years away actually had life?"
] | [
false
] | [deleted] | [
"Spectrometry can help us learn about the chemical composition of the atmosphere.",
"There are patterns we could see that would be a good hint that life exists. For instance, oxygen tends to combine with things, so free oxygen could be a sign that life recently created it.",
"Here are some ",
"slides",
" on... | [
"Doesn't matter too much how far away it is.",
"Yes, it does.",
"In order to see a spectrum of a planet's atmosphere passing in front of its parent star, you have to have a very good signal-to-noise ratio. In other words, you have to be sensitive to very subtle variations in the amount of light your telescope r... | [
"The most distant exoplanet we've detected is about 20,000 ly away, and that was discovered through the gravitational lensing of its host star's light (meaning that we have no information about the planet itself unrelated to its gravity). With current technology we are very far from being able to detect planets mil... |
[
"Given limited resources, what sort of experiment could someone do to demonstrate relativistic time dilation?"
] | [
false
] | [deleted] | [
"Are you near a mountain? Or have a balloon? You could measure the effect of time dilation on the decay of cosmic ray muons ",
"http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/muon.html"
] | [
"I don't think it would work. Theoretically, time passes more slowly for the moving mirror, but how are you planning to measure that with a laser? The only thing I can think of is if it is going fast enough and the mirrors are perfectly straight the beams would diverge slightly. And even that is not really time dil... | [
"That's the first thing I thought of, but it would only be really compelling if you also had clear proof that muon's aren't supposed to live that long."
] |
[
"Is it possible that there are galaxies that we will never see because they are moving away too fast?"
] | [
false
] | My colleague said this could be if space itself expands. Not sure what this even means and didn't find a lot on the subject so far. Layman here. My understanding is that relativity dictates that no two things can move away from each other faster than the speed of light, so light should always be able to reach the other object... Can someone shed some light here? | [
"Your colleague is in fact right. The current limit radius of the observable universe is 47 billions of light years, every object beyond that limit is invisible to us. This doesn't conflict with relativity: it's the space itself that is expanding, not any single object that is moving beyond the speed of light. As I... | [
"I'm still confused. But I was just linked to \"Metric_expansion_of_space\" on Wikipedia, so I'm reading up on that."
] | [
"Summarizing, I guess my confusion stems from my lack of understanding the difference between special and general relativity. Since I won't understand that in the near future I'm giving up on the topic. Thanks for trying to help though :)"
] |
[
"How to distinguish between an unstable atom and an element with a very short half-life?"
] | [
false
] | Oganesson, the current last element of the periodic table, has a half-life of merely 0.89 milliseconds. Are there other standards that deem it to be a genuine element instead of a bunch of stuff forcibly bound together? | [
"The IUPAC has decided that the ",
"criterion for discovering a new element",
" is the following:",
"‘Discovery of a chemical element is the experimental demonstration, beyond reasonable doubt, of the existence of a nuclide with an atomic number Z not identified before, existing for at least 10",
" s.",
"... | [
"You are absolutely right. A nucleus having a very small lifetime is called a resonance. Despite not living much, you can detect them by searching for an increase of the production probability of that given nucleus at the energy of the resonance.",
"As to why this is important I will give you just a simple exampl... | [
"Wouldn't a physicist still be interested in shorter lived elements to some degree? It might not be relevent to chemists but I would think even short lived stability would have some impact on more fundamental physics if for no other reason than to understand the nature of such instability?"
] |
[
"May be a dumb question, but why do some things (like bouncy balls) bounce, while others (like watermelons) explode on impact?"
] | [
false
] | Was just thinking about this, and realized I don't actually know the answer. I mean, if I were asked, I'd probably guess something like a watermelon is more brittle, but at the same time I also feel like if you filled one of those huge hollow rubber balls with liquid, it would probably explode too, so there must be more to it than just that, right? I'm also not super science-literate, so ELI15-ish where possible? And thanks in advance! | [
"Elastic vs. plastic deformation, tensile/compressive strength, and brittleness vs. ductility/malleability.",
"Elastic vs. plastic",
" is like the difference between dropping a gummi bear and a chocolate bar, one bends but reverts to the original shape, one bends and stays bent (dented).",
"Strength (in this ... | [
"It is actually a couple factors at play. First though, it is important to understand that many materials can be thought of as springs, even though they do not seem as such in real life. ",
"These springs are actually the atoms of the material. When a material is not under stress, atoms in it are all spaced ap... | [
"Wow, thanks for such an in-depth reply. I think I get it. One question, though. You said a ball filled with water will be heavier (which I get) and have a decreased number of molecules, but with all the water molecules inside the ball, wouldn't there actually be an increased number of molecules? Or am I misunderst... |
[
"Is there a physical difference between “true” yellow light and a red/green mix?"
] | [
false
] | I've been trying to wrap my brain around the whole light physics stuff lately, and here's one of the (many) things that still eludes me. So the perceived color of visible light is a function of its wavelength, right? But at the other hand, our eyes have only receptors for red, green and blue light, so any color we perceive must be a combination of those. Now, I can sort of understand how yellow light at ~600 nm would trigger both our red and green perceptors, seeing that it sits in the middle of those two in the spectrum. But if I mix pure red and green light, it clearly has the same effect, as witnessed on CRT and LCD displays. But does this process actually somehow yield pure yellow light at just one wavelength, or is it just that our eyes can't tell the difference? In other words, is there a measurable physical difference between single-wavelength light and the RGB mixture that produces the respective color in our eyes? I should probably mention that I have a background in audio, so I tend to intuitively think about it the same way I think about sound waves, even if I know that that'll do me no good :P Great explanations, guys. Thanks a bunch! | [
"You can flash red light briefly (~10ms) followed by green light (~10ms) and you'll perceive a single yellow flash. It's called \"cortical yellow\". It's still an open question whether or not this happens at the level of the eye or of the brain, but some neat tricks (for example, you can do it binocularly - red lig... | [
"See: \n",
"http://de.wikipedia.org/w/index.php?title=Datei:Cone-response.png&filetimestamp=20050707063120",
"there are three types of sensors in your eye, which respond like shown in the graph to a certain frequency (its the red, blue and green curve).\neach frequency creates a unique pattern of the 3 values. ... | [
"You could take the light coming out of the TV and split it with a prism, and so be able to distinguish a pure yellow from a red/green mix. That means that there is a real physical difference. If you want to think about it like audio, having red/green/blue receptors is analogous to only being able to perceive sound... |
[
"If someone had every element on the periodic table could they in theory create any compound through a series of reactions?"
] | [
false
] | null | [
"There are no known compounds of Helium or Neon, as far as I'm aware, so sadly not.",
"As you may have learned in High School Chemistry, the elements on the far right of the periodic table are called the Noble Gases. They have unusually stability/un reactivity due to their electronic configurations and so don't n... | [
"Yes and no. It depends on how you frame the question.",
"Every atom in everything you can see, touch, taste, or feel was either created shortly after the Big Bang, or in a supernova. Every compound in existence ",
" ultimately formed from its constituent elements.",
"It's not feasible for humans to reprodu... | [
"Since you can ",
"buy xenon difluoride",
", it can't be that unstable."
] |
[
"Are the surface irregularities on a column of high pressure faucet water due to the aeration of the water exiting the faucet or due to the turbulence in the water?"
] | [
false
] | When you turn on the water in your faucet at high pressure, the water looks gray. I know this is because of surface irregularities in the water column that reflect light at various different wavelengths and the fact that our eyes samples the light and average it as a middle gray color (correct me here, if I'm wrong on any part). What I'm wondering is if these surface irregularities are due to the turbulence in the water column or because they have been aerated through a mesh in the faucet leaving them full of air bubbles. I would test this out but I do not have a faucet without an aerator that can be easily removed. I tried capturing these in photo as best as I could to demonstrate what I mean. Please note that I have edited the contrast, sharpness, and clarity in these photos to better display the flow behavior. Water column at mid-pressure (you can see the air bubbles inside): Water column at max-pressure (surface irregularities are clearly visible): | [
"Well, the aerator is generating turbulence as well as density irregularities (air bubbles) in the flow. The higher the pressure, the higher velocity, and the more turbulence is created. More turbulence means it takes less time for perturbations to grow large because they're starting somewhat large already. It a... | [
"Well the aerator adds turbulence to the flow as well so there's that effect too (google \"grid turbulence\"). Higher velocity will cause more grid turbulence here. ",
"But in general, surface irregularities are going to be caused by a combination of flow irregularity (like turbulence or bubbles in the flow) co... | [
"As for what's responsible - turbulence in velocity or the air bubbles... it's kind of a chicken and egg question. The aerator causes turbulence which causes the air bubbles. But ultimately, they will both contribute. There's gonna be leftover grid turbulence which gets amplified. There's also gonna be density ... |
[
"Is it good or bad to have fluoride in our water supply?"
] | [
false
] | I hear people for and against fluoride. People who claim it's good, say it's needed for our teeth. People who are against it say it's slowly killing us, that it's a poison and it sedates the population. Whats the real truth about having fluoride in our drinking water? | [
"I'm sure fluoridealert.org is a fair and unbiased source. It refers to a retracted paper."
] | [
"The study confirmed previous findings of an inverse relation between fluoride concentration in the drinking water and dental caries in children.",
"Community Dentistry and Oral Epidemiology Volume 38, Issue 3"
] | [
"The thing is, it's beneficial at small concentrations, but as you increase the concentration it starts causing fluorosis and other diseases. The measured levels at most municipalities are far below that threshold, however, meaning that it's doing by far more good than harm. The conspiracy theory idiots are unabl... |
[
"What is it about wax and a wick (candle) that makes the wick not burn to cinders quickly?"
] | [
false
] | null | [
"Candle wicks are designed to draw liquid fuel into their own bodies and provide a steadily burning flame. Candle wicks are generally made of braided cotton around a core that gives the cord its rigidity (so that it stands up). The composition and position of the candle wick affects how a candle burns.",
"So, bas... | [
"am I right in thinking that neither the solid or liquid wax burns, but the vapour, which is evaporated from the surface of the wick by the heat of the flame, so the wick is protected by the liquid wax, apart from the very tip of the wick which either evaporates the wax too quickly, or can't draw enough wax up to p... | [
"That is about right. "
] |
[
"Why are the mirrors on the newer telescopes shaped like hexagons?"
] | [
false
] | I've seen in the news that there's going to be a big telescope in Chile, or Argentina? Can't remember. Anyways, the mirrors are tons of small hexagons. Why this shape and not squares or triangles? | [
"Disclaimer: amateur astronomer. I have a clue, but no guarantee that I'm right!",
"In the past, large telescopes like the 200\" at Mt. Palomar would be just one large circular mirror. When you try to scale up much beyond that, you get problems like the mirror sagging under its own weight, ruining the image. T... | [
"Another comment says they start with circular mirrors and cut away the edges. I think the word \"harder\" is probably incorrect, but you'll have to cut away (and thus waste) more of your circular mirror to get a square than you will to get a hexagon. Perhaps they meant \"more economical\"."
] | [
"For the same \"diameter\" of the mirrors you need fewer hexagons than squares or triangles, and the hexagon shape avoids sharp edges. It is closer to circles which means you can use existing infrastructure with smaller modifications. It also means you only have to put together three components at the corners, not ... |
[
"What causes the \"post orgasm blues\"?"
] | [
false
] | Is it just that you're going from such a good feeling to nothing in a short period of time? Or is there a different explanation? | [
"It's known as ",
"Post-coital tristesse",
" -- sexual intercourse leading to feelings of melancholy."
] | [
"I have no experience of what you are talking?",
"Is the feeling accompanied with shame? If so, you might can find a new partner."
] | [
"In French it is called ",
"La petite mort",
"."
] |
[
"How will a potential manned mission to mars transport enough fuel and technology to break grip of martian gravity to come home?"
] | [
false
] | When looking at the size and scope of a earth liftoff just to ship something on a one-way trip to mars, I don't see how any trip could possibly bring the boosters and fuel needed to come back. Are there plans for this? | [
"Actually, the plan would probably be to launch quite a few Rockets the size of a saturn 5. Some would be met up with in earth orbit, some in mars orbit, and some even in mars orbit on the return flight (or just the same cabin they took the trip in and then left in orbitaround mars while they landed in something th... | [
"I know that for the fuel to return there are plans to gather elements in the atmosphere of Mars to make fuel for the return. As for the boosters, it is not nearly as hard to leave Mars's atmosphere. The gravity on Mars is only 38% that of earth's and the atmosphere is less than 1% of earths, so I don't think boost... | [
"Assemble it in Earth orbit."
] |
[
"If we are creating super bugs by over using and incorrectly using antibiotics, are we doing the same by cleaning our hands and disinfecting surfaces etc?"
] | [
false
] | Out damn spot. Is this an issue at all? | [
"I'm not sure why this got downvoted. This is the correct answer.",
"Hand sanitizers use alcohol. Alcohol kills everything. The \"0.1%\" of bacteria that are left are alive because they did not come in contact with the alcohol. It's not that they survived the contact and are evolving.",
"The problem with antibi... | [
"I'm not sure why this got downvoted. This is the correct answer.",
"Hand sanitizers use alcohol. Alcohol kills everything. The \"0.1%\" of bacteria that are left are alive because they did not come in contact with the alcohol. It's not that they survived the contact and are evolving.",
"The problem with antibi... | [
"I'm just going to be really anal on a few of your statements:",
"As far as we know, bacteria cannot become resistant to things like isopropanol or iodine.",
"Endospore forming bacteria are resistant to those things. If you are a nurse working with someone with ",
" and you use something like isopropyl alcoho... |
[
"Have scientists really discovered a new state of matter?"
] | [
false
] | Just saw an article posted in but its supposedly a real discovery. I am very curious to hear actual scientists weigh in on this. This is the Have they really discovered a new state of matter, or that a misnomer? Is this legit? What have detractors said about this, the experiment and the phenomenon? | [
"I'm not a physicist, but I'm familiar enough with scientific journalism to tell you that answers to this kind of question (about claims made in science journalism, that is) can usually be found by clicking the link at the bottom to the actual article in question.",
"In this case, ",
"the article can be found h... | [
"Actually, in the last paragraph of the Nature paper, the authors list one of the potential applications as \"the exploration of a novel quantum matter composed from strongly interacting, massive photons.\" I'm not sure if that's just the authors being overexcited about their results though.",
"Matter is a poorly... | [
"Physicists with more background, please, feel free to correct me. So, a few things.",
"Ice, alone, has 15 distinct states.",
"Bose-Einstein condensate",
"The article is written in such lay-language, however, it is really hard to tell what they are getting at. I'm absolutely sure that the scientists in questi... |
[
"Is there a physical limit to how fast a human being can run?"
] | [
false
] | null | [
"Yes. ",
"Several sources say this, but LiveScience did a great summary",
" ",
"Essentially, 40 mph. At that point, too much force is shocking the muscles, breaking them. And the brain will shut down from too much energy exertion"
] | [
"In the linked article, it says that Usain Bolt has maxed at 28 mph... and never surpassed"
] | [
"40 mph is theoretical. It would have taken seriously extraneous amounts of energy to have reached 40 mph in the first place. The acceleration to the point of that velocity is the hardest part"
] |
[
"What is the pressure of blood in our arteries?"
] | [
false
] | Blood pressure is measured traditionally in millimeters of mercury, and that conversion is simple enough to pounds per square inch, with 100mmhg being roughly 2 psi. But the pressure being measured is the pressure inflating a cuff sufficiently enough to occlude the veins in the arm. My question is: how does that measurement correlate with the actual gauge pressure of the fluid in our arteries? I'm intuitively willing to accept they're proportional (are they?) but it doesn't make sense to me that they'd be equal. Thanks, science! | [
"That's why you also have to listen with a stethoscope as you inflate and deflate the cuff. You first inflate it so that the artery closes off completely and then you back it off, deflating until you hear the beginning of blood flow which has a ",
"distinctive sound",
" and that's when you know that you've equ... | [
"In my line of work, we will frequently cannulate an artery to transduce blood pressure directly. The pressure is essentially equal to that obtained with a blood pressure cuff, although there is a small amount of error with the cuff in both directions from measurement to measurement (perhaps 5% at most, and more s... | [
"the pressures are actually the same. think of it like a hose. if the water in the hose is exerting 1 psi on the wall of the hose, and you put a box of sand that exerts .999 psi on the hose, there would still be water flowing, but if you put just a little more sand so that it now exerted 1 psi on the hose, it would... |
[
"Why do some people pass out when seeing blood?"
] | [
false
] | null | [
"I don't know about particular theories related to blood or violence in particular, but the \"fainting\" reaction related to all stressful situations is called a \"vaso-vagal reaction.\" To some, a stressful situation is seeing blood or violence. The stress overstimulates the nucleus tractus solitarii in the brains... | [
"The pain sensor nerve cells that give you the deep throbbing pain have unmyelinated axons (they don't have \"insulation\"), so they actually conduct at slower speeds than the myelinated sharp pain sensory neurons that let you know that you injured yourself."
] | [
"Is this why often times when you just injured yourself, you feel fine at first, and after a few seconds (seeing blood, perhaps?), the pain kicks in?"
] |
[
"Why do we hiccup?"
] | [
false
] | null | [
"It's a left over nerve action from when we were fish millions of years ago. ",
"Your lungs used to be swim bladders in fish and fish had an automatic way of adjusting the swim bladder to be higher or lower on the water.",
"\nFor us this auto system now manifests as hiccups.",
"What triggers hiccups? Actuall... | [
"There are a few triggers for hiccups but the most common one is swallowing large amounts of air, such as when one is eating too quickly."
] | [
"I don't think that's even possible.",
"I suspect it's triggered when you breath in but windpipe is closed (epiglottis is closed) so you get a negative pressure or something that irritates a nerve"
] |
[
"Why do certain noises hurt to us? (Nails on a chalkboard, rubbing styrofoam together, etc)"
] | [
false
] | null | [
"It's still a mystery, but recent research found that, if you don't know that it's ",
"from styrofoam, or squeaking chalk, then it's not nearly as horrible."
] | [
"The investigation of sounds with certain frequency ranges modified seems familiar, but I don't remember reading about the effect being dependent on knowing what's making the sound. That's pretty interesting, and might be a problem for the warning call theory: if you hear a warning call, but you don't know it's a w... | [
"I'm not a biologist, but i actually know the answer to this one! ",
"A proposed reason for this, is that the Human ear canal is shaped to amplify frequencies significantly between the 2000-4000hz range, which is roughly the frequency of the human voice. Because of our reliance on verbal communication, our ears a... |
[
"When a food has sugars on the nutritional value section, what type of sugar is it?"
] | [
false
] | null | [
"Here in the US, the type of sugar isn't identified. The sugar in unadulterated dairy is lactose (a complex disaccharide, or double sugar, composed of galactose and and glucose) but not listed as such. Sugars in a simple fruit jelly would be both fructose (fruit sugar) and sucrose (table sugar, from cane,) and poss... | [
"While not identified on the nutrition label, many if not all companies will list the different types in the ingredients. That may be a legal requirement, or they might do it because it allows them to split up the sugars so they make up a smaller percentage, allowing them to appear further down the list of ingredie... | [
"Following up on this, where do they draw the nutritional line between \"sugar,\" \"carbohydrate\" and \"fiber?\" My understanding is that chemically speaking, they're ",
" technically carbohydrates, but of varying saccharide chain length."
] |
[
"Can ears become insensitive to certain frequency ranges?"
] | [
false
] | My father is getting fever (for seemingly unidentified reasons) since more than 20 days, so I bought a thermometer. Now for some very weird reasons, he is not able to hear that 'beep' sound which notifies that thermometer has completed measurement at all? He is 60 but he otherwise can hear all the sounds, in fact even lower volume sounds pretty decently. He could hear very faint voice from his phone far away while measuring fever and mistook it for beep. I told him it was not thermometer. Then, when it was actually beeping, he was literally holding it in hand and asking me me if it is beeping??! I only tried with my mother once, but she also couldn't hear it, however, she hears less on one ear so it didn't surprise me much. That leads me to the question whether this is a known phenomenon? The only plausible explanation I could think of was that beep was of constant frequency (I don't know proper term for it but 's same sound you would get if you would supply a speaker with dc signal) and his eardrums don't vibrate at that frequency perhaps due to aging. PS : I'm new and couldn't decide what would be a better flair, physics or human body. | [
"The main issue isn’t the eardrums, but the hairs in the cochlea that sense individual frequencies.",
"Basically, the ear drum transmits vibrations through some other funky looking bones to a wound up bit of cartilage called the Cochlea. Inside the cochlea are strategically placed hairs. Depending on where in the... | [
"Yes. It’s very common to have hearing loss in the upper ranges as we age. Our eardrums stop having the flexibility to vibrate at those frequencies as they get older. Totally normal. And might be helped with a hearing evaluation."
] | [
"You can have dead ranges of the cochlea absolutely. Specific frequencies for which the hair cells don't work.",
"He's also ill at the moment which ",
" cause a middle ear infection, dropping his hearing by a bit. But a conductive loss like that should affect the low pitches more.",
"So this sudden loss for h... |
[
"There appears to be a monumental military/science experiment going on in a Chinese desert, visible on Google Earth. Can anyone tell what exactly is happening here?"
] | [
false
] | null | [
"\"Exactly\" what is happening, no, but there are a LOT of reasons to do this kind of thing, not all of them requiring tin-foil hats. Monumental is a bit of an overstatement, it's mostly white plastic on the ground. Also of interest is that it doesn't follow topography. It's meant to be viewed orthogonally.",
... | [
"Having watched this area and activity for years when I was in the military. There's several things that you've found out here. Some of it is \"cool\" and some of it is just random.",
"The Gobi area is rife with military activity. The Chinese frequently use it as a military training area. They use it to test ... | [
"For the record, 'tin foil hats' are actually quite effective at amplifying signals from two specific wavelengths.",
"MIT investigation",
"Among a fringe community of paranoids, aluminum helmets serve as the protective measure of choice against invasive radio signals. We investigate the efficacy of three alumin... |
[
"What is the scientific response to Shmuley Boteach's assertion on the probability of evolution"
] | [
false
] | [deleted] | [
"Shuffle a deck of cards.",
"The chance of that deck coming up by chance is 1:10",
".",
"By that logic, shuffling a deck of cards is impossible.",
"Evolution is a scientific fact and anyone arguing against it should pretty quickly be dismissed as lacking scientific expertise. "
] | [
"He points out that mutations are generally bad, and uses this as an argument for intelligent design. ",
"The problem is, as long as these bad mutations are selected against, they die out. The one-in-a-million beneficial mutations are favored by natural selection, and thus become more common in the population. ... | [
"mutations are generally bad",
"Most mutations are neither bad nor good. "
] |
[
"If clams have nerves but no brain to interpret signals, how can they feel pain?"
] | [
false
] | [deleted] | [
"Consider a human touching a hot pan. The body reacts by pulling away before the pain is ever 'felt'. Feeling the pain was not a prerequisite to reacting to it."
] | [
"Its difficult to say how and what other animals feel, especially one as different from us as a clam. In reality, they likely don't \"feel\" anything, merely react to stimuli. That being said, even simple creatures like clams are still treated as if they can feel pain in the lab, and are treated with an anesthetic ... | [
"This question gets to the heart of what pain is - \"an unpleasant sensory and ",
" experience associated with actual or potential tissue damage, or described in terms of such damage,\" according to the ",
"IASP",
" (emphasis mine). Clams have a nervous system but do not have a brain capable of emotional or a... |
[
"Do all people of the world have similar bacteria on their bodies and in their homes, or are there distinct breeds of bacteria for every continent?"
] | [
false
] | Is there such a thing as New World bacteria and Old World bacteria? | [
"I'll add to this that, besides the fact that many human-living microbes and viruses are becoming more cosmopolitan due to the interconnectedness of the modern world, there is some seriously interesting stuff going on in microbiome studies.",
"The human microbiome is the sum total of species living on or inside u... | [
"Just like how certain animals live in certain places, so do bacteria. Not every bacteria can be found everywhere. That being said, because of the increasing amount of globalization, more \"germs\" can be found in the same places. ",
"Take smallpox for example. Until the Europeans arrived from their respective co... | [
"The composition of species comprising the gut microbiome is heavily influenced by diet, which generally speaking is influenced by the environment of the host. Many studies have showcased that the typical Westerner's gut has a very different balance of the two major bacterial phyla found in the gut, compared to say... |
[
"Why is integration the opposite of differentiation?"
] | [
false
] | [deleted] | [
"Let f(x) be some function and let F(x) be the area-under-its-curve function (say, the area under f(x) between 0 and x).",
"Think about the derivative of this area function. If you increase x by a little bit, you increase F(x) by adding on approximately a rectangle of height f(x). There's a pretty good ",
"pict... | [
"...and FWIW, ",
"here's",
" Herb Gross' wonderful lecture on the Fundamental Theorem. OP may or may not be able to jump into the middle of a lecture series, but it's a pretty swell explanation."
] | [
"I always find math a little easier to understand when you think about in terms of describing a physical property. And with calc I find distance, velocity and acceleration. ",
"So what are you measuring when you take a derivative? You're measuring the rate of change of the dependent variable to the independent va... |
[
"If Earth was located in another orbit, further away from the sun, would the sky have a diferent color?"
] | [
false
] | I'm guessing "yes" but if we were really far away. | [
"If the atmosphere remained constant, then the only change you would see when pushing the Earth further away from the sun would be that everything would look darker, but the actual color (i.e. spectral color) of the sky would not change. The reason is that the color of the sky is only determined by two things: 1) t... | [
"Unfortunately there's no simple answer to that. ",
"This has been asked before",
" and there are good answers in that thread. tl;dr: it's a combination of factors:"
] | [
"The one thing I don't get is why the sky isn't violet seeing as it should be scattered the most efficient "
] |
[
"Are there screens that can display all colours?"
] | [
false
] | So it's impossible to make every colour using only three primaries, and what's more, apparently most screens use sRGB which only covers 30% of the CIE colour space. Is there anything that covers 100%? | [
"Covering more of the full horseshoe-shaped CIE chromaticity space in the ",
"Wikipedia link",
" comes down to two things:",
"To directly answer the original question, there is nothing that covers 100%.",
"In the future, there may be tech that uses tunable lasers to emit exact spectral color, hitting any po... | [
"Hey, thanks for the answer and info! I had given up hope.",
"\nIf you don't mind, I'll ask a couple more questions.",
"We're a very long way from turning those lasers into a screen, right? It's nice to know there's a possible path though.",
"\nIn the meantime... looking at the wiki page on ",
"sRGB",
", ... | [
"Yes, as far as I'm aware there have been no published successes (or even attempts) of making a display with tunable lasers, although you can buy screens and projectors that use fixed-wavelength lasers.",
"The reason that the sRGB triangle looks brighter at the edges is because that graphic is designed in a confu... |
[
"Is there a book that will get me from mechanics to quantum physics (or at least far ahead), that also teaches the math that is included?"
] | [
false
] | null | [
"No, there is no one single book which will do all of that.",
"For the math, there is Boas' ",
". She gives some physical examples varying from classical mechanics, electrodynamics, etc."
] | [
"I am a Ph.D. student in physics."
] | [
"Yes."
] |
[
"Why doesn't dark matter inexorably collapse into black holes?"
] | [
false
] | As I understand it, dark matter interacts with matter primarily of exclusively through gravitation. Given that, it seems that any clump of dark matter would inevitably grow denser as it attracted more dark matter. In the absence of normal repulsion forces (particle interaction-based pressure/quantum mechanical exclusion shenanigans) what prevents this clump from automatically collapsing into a point? In my head the evolution equations look like Euler's equations with a negative pressure/density dependence which sort of looks like a backwards heat equation-the father of singularities. Why isn't that what happens? | [
"Short answer: conservation of angular momentum and lack of friction.",
"Long answer: most dark matter lies in and around galactic disks. In this regime, gravity acts mostly Newtonian, and Newtonian gravity conserves angular momentum. This is the reason it's actually rather hard to capture moons, asteroids, etc... | [
"I'm not sure what this response has to do with the comment you're responding to.",
"It's true that the black holes out there in the Universe most likely have negligible electric charge and therefore only interact gravitationally (barring any \"fifth forces\" through which they might also interact), but that's a ... | [
"You could just as well ask why all the planets don't spiral into the Sun - after all, they only interact through gravity, right? Or why the stars in the galaxy don't all collapse into the center. It's the exact same question.",
"Except it isn't quite. Dark matter haloes are actually ",
" likely to collapse int... |
[
"Why, in a circuit, does electricity travel both directions in a junction and not just through the path of least resistance?"
] | [
false
] | null | [
"As ProblemIsInPants said, going through both resistances is the least resistive path. If you consider two (or more) resistors in parallel, the equivalent resistance is given by the formula",
"Req = (R1*R2)/(R1+R2)",
"So Req is ",
" smaller than R1 or R2 (check yourself if you don't believe me). It's always \... | [
"Here's a metaphor: If you punch a bunch of holes in the bottom of a bucket of water, why doesn't all the water flow out just through the largest one? ",
"People sometimes say \"Electricity follows the path of least resistance.\" People also sometimes say things that are incorrect, and this is one of them. Ele... | [
"The path of least resistance is the one where both paths are used. Even if the other path has a huge resistance compared to the other one, some goes through there."
] |
[
"How was the speed of light first measured to some degree of accuracy?"
] | [
false
] | null | [
"https://en.wikipedia.org/wiki/Speed_of_light#First_measurement_attempts",
"This page has some listings you might find illuminating"
] | [
"You can also try ",
"/r/askhistorians",
", ",
"/r/philosophyofscience",
", ",
"/r/historyofscience",
", and ",
"/r/historyofideas"
] | [
"I believe it was by Rømer, who used the moons of Jupiter:",
"https://en.m.wikipedia.org/wiki/Rømer%27s_determination_of_the_speed_of_light"
] |
[
"What makes a gas a greenhouse gas? For example, what are the molecular properties of carbon dioxide (CO2) that allow it to retain heat, that nitrogen (N2) lacks?"
] | [
false
] | null | [
"Greenhouse gases absorb and re-emit infrared radiation. This means that instead of passing through the atmosphere and directly into space, some of the infrared radiation is re-emitted back toward the surface of the earth, increasing the net heat on the planet's surface. If it were re-emitted in the same direction... | [
"Just to tack on to the last sentence - molecules that have vibration frequencies that can be perturbed are polyatomic. This has to do with the vibrational frequency degrees of freedom. Linear molecules (all diatomic, some polyatomic) have 3N-5 degrees of freedom, where N is the number of atoms. So a diatomic molec... | [
"So a diatomic molecule has (3x2)-5 = 1 vibration frequency.",
"This is technically right, but it's a bit more complex than that.",
"Saying that a diatomic molecule has one vibrational frequency sort of implies that it can only ever vibrate at a specific frequency. It would be more precise to say that they hav... |
[
"How difficult is it to \"clean up\" radiation?"
] | [
false
] | Is dumping water and concrete on it the most efficient way we have as of now? | [
"Cleaning up radioactive waste is an extremely processing-intensive procedure. To dispose of radioactive waste (generally in the form of a thick sludge), it must be vitrified (basically locked away in glass) and sealed in thick metal canisters. Vitrification (and glass science in general) is a very complex science ... | [
"There's no way to just make the radioactive particles stop being radioactive. You have to immerse them in something that prevents the radiation from escaping; concrete is used because it strikes a good balance between ease of transport/use and power to block radioactivity, and water is used because it's easy to re... | [
"Does the water that is used to cool the fuel rods in a power plant become radioactive? Does it have to be filtered or processed somehow before it is released into the environment?"
] |
[
"Question about relativity and I think what is called the \"twin's paradox\" after reading Hawking's \"A Briefer History of Time.\""
] | [
false
] | Okay, so one twin is born at sea level and the other on the top of, say, a mountain 100 million miles high. The twin on the top of the mountain will age slower, let's say twice as slow. If the sea-level twin were to take a telescope that could see faster than the speed of light, in instant-time, would the mountain-twin be moving in slow motion? What if the telescope were limited by the speed of light reflected off the mountain twin's skin? (I believe telescopes can't actually see that far.) *I think I am correct in saying that the person closer to gravity ages faster, not positive. It has been 8 months since I read Hawking's book. | [
"Okay, so one twin is born at sea level and the other on the top of, say, a mountain 100 million miles high.",
"We're going to change that to \"100 miles\" in order to at least keep our thought experiment in the realm of the not-entirely-ridiculous. It doesn't affect the maths.",
"The twin on the top of the mou... | [
"No question is stupid. All corrections that are applied are applied during the processing of the data. The data you receive from a GPS satellite is, more or less, the range (uncorrected for satellite error) in meters (based off of satellite clock transmission time and ground receipt time multiplied by the speed ... | [
"Great response, I'm just here to clarify the relativity portion of the GPS explanation.",
"Relativity and clock drift are two different things. The error due to relativity on the GPS signal is something on the order of 10s of nanoseconds (equates to a couple meters of accuracy) at any given time and arises due ... |
[
"Do the different types of genetic mutation occur at equal rates?"
] | [
false
] | Specifically talking about transition, transversion, addition, and deletion (or more, if there are other types I haven't read about yet). | [
"I imagine substitution is more common than indel, because the latter produces much worse effects (frameshift mutation). So there should be a strong selection pressure against indels. Transition (A-G or C-T) is much more common than transversion (A-C or G-T).",
"Overall, the most common mutation is a ribonucleoti... | [
"I'm designing a simulation for bacterial mutation. I saw the overall mutation rate was on the order of 10",
" per base pair and S. Aureus has 2.8x10",
" base pairs approximately. Thanks for the info, with that I can make the simulation a little more realistic."
] | [
"I see. Prokaryotes are more complicated. You may need to factor in ",
"GC skew",
" (different strands of dsDNA have different mutation rates) and ",
"mutational codon bias",
" (different codons have different mutation rates). To be completely accurate, you also need to look into repair rates (or maybe your... |
[
"How small can a gas planet be?"
] | [
false
] | null | [
"Uranus has the lowest mass",
"Uranus is slightly larger in mass.",
"Which one is it? :S"
] | [
"This is very temperature dependent, the reason planets lose atoms/molecules of gas is mainly due to thermal loss, atoms which have sufficient energy to get to escape velocity and leave the planet. For small planets the energy required is very low (compared with say, the same thing on the earth) and a high fractio... | [
"Because of the (currently considered correct) model of planetary formation, called \"core accretion\", it is estimated that a planet must be ~5-10 the mass of earth. While it might be that much larger than mass of earth, it's diameter will be larger, because of an average lower density in gas planets. But, because... |
[
"Are poodles really hypoallergenic?"
] | [
false
] | I know several people who have poodles because they are supposedly "hypoallergenic." What's the basis of this claim? What gives a poodle this magical quality that other dogs don't have? | [
"Relevant wiki link.",
" The gist of it is that poodles are not truly hypoallergenic; all dogs shed and therefore can provoke allergies. However, their fur sheds less frequently, and loose fur and dander tends to be more effectively trapped by their curly fur than that of other dog breeds. In addition, many poodl... | [
"As far as I'm aware, hair and fur are both keratin growing out of follicles. I'm not sure what the distinction you're making is."
] | [
"Thanks for this. However, in regards to your statement that they shed allergenic proteins less frequently-- By following links in the article you referenced, I found a reference to a study that tested levels of allergens in the homes of dog owners: ",
"http://www.ingentaconnect.com/content/ocean/ajra",
"No cl... |
[
"Please help me help 8-year-olds understand how heat and light affect evaporation!"
] | [
false
] | I'm an elementary school teacher preparing a science lesson for my students' upcoming unit on the water cycle. I'm not sure my school administration envisioned the teachers they're trusting to build the school's curriculum going to reddit for answers, but all of the textbooks and websites I usually check to make sure I'm not completely screwing up the way my students understand the universe have slightly different answers on this one. I don't want to synthesize them into my own best guess and, in doing so, risk giving incorrect information to my students. My kids will be doing an experiment which will result in their understanding that water evaporates more quickly when it's left in sunlight. All of my sources are pretty clear about the role of heat, and I anticipate that my students will definitely get that increased heat results in an increased rate of evaporation--I'm going to activate prior knowledge by bringing up boiling water for them to reach this conclusion if they don't get there from the experiment alone. My sources are less clear on the impact of light. Some imply that light has a unique role in making the water evaporate more quickly. None of those explain how. The others don't mention light at all. I need to know if light affects the rate of evaporation and, if so, how. If possible, language that I can translate into 8-year-old-speak would be appreciated! Thank you! | [
"1) Light directly heats up the water. Refer back to what they know about hot water.",
"2) Light itself is made of photons which are basically packets of energy where the energy depends on the color of the light. For example, green light is made of photons with about 2.33 eV of energy. For water at room temperatu... | [
"The reason things evaporate is that not all of the water molecules in the glass of water (or whatever) have exactly the same energy. ",
"There is a certain threshold amount of energy that a water molecule needs in order to leave the liquid body of water it is in and become a gaseous molecule. Imagine a gatekeepe... | [
"Thank you for answering. This makes sense to me, and I know I can easily make this example work for my students. ",
"I think that my language in framing and phrasing my question was a little unclear, though--in fact, I think some of my word choices reveal that I need to do some more looking into what I mean by... |
[
"Is there a lifeform which does not use DNA/RNA for its genetic code?"
] | [
false
] | [deleted] | [
"I’ve taken more genetics courses and read more genetics papers than I care to admit to, but I’ve never heard of such a thing. DNA/RNA is one of the basic necessities of life. Are you sure you didn’t read a paper that was extrapolating the idea of DNA-less life?"
] | [
"It was probably that strain of Halomonadaceae from Mono Lake that was hyped a few years ago, because it was thought it could substitute arsenate for phosphate in its DNA, which turned out to be not so correct."
] | [
"https://digital.library.unt.edu/ark:/67531/metadc832429/m2/1/high_res_d/1016932.pdf",
"That was the original, but it's largely refuted by now. The strain is arsenic tolerant, but depends on phosphate."
] |
[
"Do oxygen levels drop in areas during night time?"
] | [
false
] | [deleted] | [
"I'm not an expert, but some plants do produce oxygen at night. Orchids are an example. "
] | [
"Yes, plants convert oxygen and sugars into energy and carbon dioxide the entire day. But while photosynthesis takes place the amount the plant needs for itself is negligible compared to the amount it releases into its enviroment. ",
"So at night most plants release carbon dioxide and no oxygen and thus the oxyge... | [
"Yes they are. But as long as photosynthesis occurs, the amount of oxygen produce is larger than the amount consumed. At night, photosynthesis stops, but plants keep on consuming oxygen. (the total consumption of oxygen is lower than the production of oxygen if you take the average through the year). You learn that... |
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