title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Does rain dampen or increase the strength of smells?"
] | [
false
] | Tobacco for instance. Edit: Clarification: I meant if the smell is on something, not just wafting in the air. So for instance I went outside to smoke a cigarette and had to walk ~100ft through the rain to go inside. Did that rain dampen the smell or make it worse? Does this apply to all scents? | [
"I should've specified but I meant if the scent is on an object as opposed to wafting around in the air."
] | [
"It's along the lines of what I thought, that both dampening and increasing the smell are possible outcomes."
] | [
"That makes sense, thanks for the answer."
] |
[
"How long could the Earth last."
] | [
false
] | If the Sun were to remain at a constant temperature and never died how long could the Earth theoretically last to support life? How long will it take for Earth to become a dead planet like Mars? | [
"Quite a few billions of years.",
"The atmosphere is the most fragile part. Some planets lose atmosphere over time, as energetic gas molecules escape the planetary gravity and float off into space. But Earth's gravity is too high and its temperature too low, for this to happen significantly. If nothing changes, w... | [
"Well the sun is a whole lot more active. It's an uncontrolled bomb that fuses something close to a billion tons of hydrogen every second. The Earth is just a big, slightly damp, slightly warm rock. :)"
] | [
"If the Sun ",
" died/changed, there is no reason that the Earth's present state could not persist essentially forever. Over a very long time (many billions of years), there would be problems with atmospheric loss and on the next largest time scale, eventually the Earth would cool and plate tectonics come to a st... |
[
"Why does your head hurt when you aren't dehydrated?"
] | [
false
] | [deleted] | [
"There are several types of headaches. Tension headache, the most likely culprit of your current headache, are caused by the muscle wrapping around your head spasming (contracting spontaneously). This is perceived as a head ache.",
"Migraines are more serious type of headache. I believe these are caused by high b... | [
"uhhhh, sinus headache is my best guess. It could be from dehydration as well as simple fatigue, but when I think of a cold headache I think of a sinus headache.",
"A sinus is just a cavity...and we have a few in our skulls. One of these sinuses can be filled with fluid (90% sure snot). This is why you should nev... | [
"Wait, you shouldn't \"suck in\" a running nose because the snot just collects more and more in your sinus?",
"I've been doing this for years out of laziness - I should really start blowing my nose...",
"I guess I do have a sinus headache then, considering I've had a running nose that I haven't blown out in day... |
[
"Have there been recent progress in ancient Egyptian DNA sequencing?"
] | [
false
] | I keep seeing new results on neanderthals and even woolly mammoths... but the ancient Egyptians lived just a few thousands years ago. I understand there are issues with the hot climate (so DNA breaks down faster and in smaller strands) and contamination, but there are new sequencing technologies available that would wo... | [
"Possibly because we've already sequenced the human genome and as you said, they were alive (are still alive, as Egyptians still exist) a few thousand years ago, and in that time frame there is no significant genetic mutations. It is likely that their genetic makeup would greatly resemble out own. "
] | [
"One of those cases of not enough scientists or money to do everything. We (and our funding bodies) have to prioritise our research targets and if it doesn't look like there is much to gain, other things get prioritised. "
] | [
"DNA is best preserved in arid environments like egypt ande east africa, it is damp tropical environments where it breaks down fastest."
] |
[
"If you could take all of the viruses out of your body during the peak of a bad flu, what volume would they fill?"
] | [
false
] | null | [
"Very little when wet, dried, even less.",
"Let me give you an example. In grad school, I worked on influenza. A couple times a year, we would do thousand egg harvests, innoculating a thousand eggs with the virus, and purifying the virus from the alantoic fluid. Out of about 6-7 liters of fluid, I'd end up with a... | [
"You might. You might also throw up, it had the consistency of snot."
] | [
"What would happen if I just straight drank that 2-4 ml of viral suspension? Would I just get the flu?"
] |
[
"Is it true that mad cow disease is caused by acts of cannibalism? If so, why is cow eating cow’s brain more dangerous than cow eating rat’s brain?"
] | [
false
] | null | [
"Mad cow disease (aka bovine spongiform encephalopathy) is caused by misfolded proteins called prions. There are two types of mad cow disease: classical and atypical. Atypical is rarer, and occurs spontaneously. Classical BSE occurs when cows eat feed contaminated with BSE-infected meat and bone meal. So yes, some ... | [
"Excellent comment. Wanted to point out that it's typically not bovine \"meat\" or skeletal muscle tissue that would be infectious but instead the tissues known as \"specified risk materials,\" which are Tonsils, Distal Ileum, Skull, Brain, Eyes, Spinal Cord, Trigeminal Ganglia, Dorsal Root Ganglia, and Vertebral C... | [
"You might be conflating a couple of things.",
"Prions that are responsible for a variety of related diseases affect the nervous system. Its possible to get a prion disease from eating the brains of an infected cow. Its also possible to get a prion disease from eating the brains of an infected person."
] |
[
"If gravity is curvature in spacetime, does that mean that when I throw a ball it is actually going straight in it's own space, but because of the earth that space is curved 'downward'?"
] | [
false
] | And if yes, can the force that is pulling me down right now be thought of as me going against the straightness of my movement? uh, so my body wants to go straight, and straight to it is down because of the curve. Am I in any way understandable? And after I've written this I see in the sidebar that disccussion should be... | [
"The short answer is yes, there is a whole branch of study of this in physics, the most relevant of these are geodesics. Standard procedure in GR is to use whatever geometry of spacetime due to the presence of mass or other parameters that we are interested in and reformulate the lagrangian, hamiltonian or other r... | [
"can the force that is pulling me down right now be thought of as me going against the straightness of my movement?",
"Here is a modified version of an answer I gave to a ",
"related question",
" a few days ago:",
"The critical thing to understand is that curved spacetime (gravity) is not a force.",
"Imag... | [
"A few comments:",
"which will offset the fact that my timeline is angled a bit toward the mass.",
"The word you want to use here is ",
"\"worldline\"",
".",
"In that sense, a person sitting on a chair is a bit like an aircraft crabbing into a crosswind as it comes in to land.",
"That's a great metaphor... |
[
"How close are we to cell phones/laptops that hold charge for a week or longer? Or better yet, wireless charging?"
] | [
false
] | null | [
"We already have wireless charging.",
"http://en.wikipedia.org/wiki/Inductive_charging"
] | [
"Indeed, inductive charging has been around for a while.",
"As for the charge, that really is so dependent on usage and the phones draw at idle that it's hard to predict.",
"I have an old flip phone that when charged, if not used, will stay charged for easily 10+ days. I also have a modern smartphone that does... | [
"There are all kind of promises about batteries that will last 10x longer, by using nanomaterials. But so far nothing commercially available. ",
"http://en.wikipedia.org/wiki/Nanobatteries",
"There are two things that draw most of the power from a cellphone/laptop: The CPU and display. Some displays, like the M... |
[
"Why can't we divide by zero?"
] | [
false
] | I mean, intuitively, 3/0 is 3 being divided by nothing...so why can't it be 3? I know I'm probably thinking about this all wrong, so can anyone clear this up? | [
"This also has to do with limits. If you're approaching it from the positive side, you'll get the above, while if you start from a negative number and work your way towards zero, you'll see that you get -infinity. The reason you cannot divide by zero is not so much that the result is infinity, but that it is both +... | [
"You can think of it this way:",
"3/1 = 3",
"3/0.5 = 6",
"3/0.25 = 12",
"3/0.01 = 300",
"3/0.001 = 3000",
"3/0.0001 = 30000",
"3/0.0000000001 = 30000000000",
"and so on. The closer you get to dividing by zero, the closer the answer gets to infinity. So, numerically, dividing by zero makes about as m... | [
"How can you put three things into zero boxes? Don't over think the problem."
] |
[
"Is there a repository of visible light pictures of space?"
] | [
false
] | I've been reading on ask science and saw that most pictures which are published are actually various spectrums of light, including ones that cannot be seen with the human eye. This makes for better looking pictures, but I was curious if there is anywhere I can see pictures of well known galaxies that only show light s... | [
"You can find a lot ",
"here",
", they are not sorted on filter, but they tell you in what spectrum the pic is taken once you click it. "
] | [
"Thanks. I found this after posting. I was mainly curious if there was a good source that had the \"doctored\" pictures side by side with visible spectrum pictures. Same exact source data, but with different spectrums filtered out, etc."
] | [
"Bear in mind that to get a pic as we see it, it needs to be made in R,G and B filters, which is not done very often, as a lot more information can be gained by adding infrared or other wavelengths. ",
"But as most of the things you see in these filters are quite distinct, you can see what belongs in what filter ... |
[
"Why does the pitch change when you zip a zipper faster/slower"
] | [
false
] | null | [
"Imagine yourself the zipper has a few points it will produce a sound on whenever you cross it. Each time you cross one of these marks it'll produce one sound wave.",
"Thus the frequency will be determined by how many marks you cross each second. Higher speed means more marks crossed per second equals more sound ... | [
"This is true, but that is the tuning fork vibrating at it's harmonic frequency.",
"If you start striking the pitchfork fast enough for the initial percussion to have an audible frequency it would make sounds of different pitch to your ears. This is what is happening with the zipper.",
"The harmonic frequency o... | [
"Would the speed at which it strikes each individual tooth in the zipper not change the pitch too?"
] |
[
"If you performed the double slit experiment with air as the medium and subject it to different sound frequencies, would you notice a change in the light pattern?"
] | [
false
] | null | [
"I not really sure what you're asking.",
"Are you saying: Can you use sound to make air into the 'double slit' and then send light through it?",
"If so, the answer is (sort-of) yes.",
"There are devices called Acousto-optical modulators that use sound waves to set up a periodic structure in a crystal, which i... | [
"Thanks for your answer. I didn't know what a AOM was until now. You are sort of on the right track as to what I was asking. The reason I asked this question stemmed from cymatics. So far, I've only seen the phenomenon in two dimensional planes such as sand on a glass pane. I was wondering if this sort of order cou... | [
"I guess that if you had nice loud standing waves in a foggy box you might see something; again, I'm not sure about the power required. Using audible sound would give nice features on the order of 10's of cm.",
"Another cool thing is that in humid air, low pressure areas would condense water into clouds. In theor... |
[
"What are some counterintuitive non-quantum level phenomena?"
] | [
false
] | In the quantum world, nothing is intuitive (particle/wave duality, superposition, nothing happens with certainty, etc.) But in the "macro" world, are there examples of processes/events that are counterintuitive? | [
"When a human being moves from a low-altitude place to a higher altitude place, their body has to cope with lower oxygen levels. One of the ways a body can adapt is to make more hemoglobin, the protein in red blood cells that carries most of the oxygen we breathe to our tissues. Some athletes will train in a high-a... | [
"The ",
"tennis racket theorem",
".",
"Babinet's principle in optics.",
"There are a lot of interesting effects in fluid mechanics, where the equations governing fluid flows can be very nonlinear.",
"This kind of involves quantum mechanics, but the differential cross section for scattering of pointlike ch... | [
"Instead, high-altitude populations have acquired mutations that enable their cells to use oxygen more efficiently.",
"Per hemoglobin levels, this depends on the high-altitude population (Tibetan, Andes, or Ethiopian) ",
"http://www.pnas.org/content/99/26/17215.full"
] |
[
"Why are heart attack victims sometimes put into a medically induced coma?"
] | [
false
] | A friend collapsed from a heart attack a few days ago and was put into a medically induced coma. Why? What are the risks to this? Thanks. | [
"Well I can't speak specifically to your friends condition but can talk around general points.",
"The most likely scenario I could imagine would be in the setting of a cardiac arrest. A heart attack occurs when one of the coronary arteries that supplies the heart becomes blocked, and as a result the bit of heart ... | [
"Brain damage will start within several minutes after cardiac arrest if there is no CPR. It certainly doesn't always occur - people can make full recoveries after cardiac arrest, but the shorter the duration of CPR the better."
] | [
"Curiously, do you feel there's much supporting evidence to agree that the amygdala is one of the first areas to see damage post arrest? I've argued this with a number of personnel, and we cannot come to a valid conclusion at this time. Anyone have good evidence for or against this?"
] |
[
"Is there a limit to how fast water can be pumped?"
] | [
false
] | If not, what sorts of variables affect how quickly water can be pumped? I watched and was interested in making my own and trying to improve upon it. | [
"More speed -> more power;",
"If turbulence is introduced or friction is significant,",
"More speed -> more energy.",
"If you're using a hand pump to pump some fluid some height differential, you absolutely cannot make a pump go as fast as you want, it would be limited by (among other things) how much power y... | [
"More speed -> more power;",
"If turbulence is introduced or friction is significant,",
"More speed -> more energy.",
"If you're using a hand pump to pump some fluid some height differential, you absolutely cannot make a pump go as fast as you want, it would be limited by (among other things) how much power y... | [
"The limit in terms of energy (or power) is of course the amount of work that needs to be done. So for example, if you're pumping water 1m higher, you need at least:",
"E~mg dh~m 10 1 = 10 Joules/kg [assumes uniform gravity]",
"If you're inflating a balloon from atmospheric pressure p0 to pressure P and volume ... |
[
"How hard was Dinosaur skin?"
] | [
false
] | All photos make it look like they had hard shells, is this just a dramatization? Wouldn't they be no more tough than a bear skin? | [
"You're forgetting the scales. Like many modern reptiles, many dinosaurs had scales on their skin. Think nonoverlapping scales like an alligator, not overlapping like a snake. Many other had feathers, or a combination of feathers and scales."
] | [
"Depends on the dinosaur. The ones with feathers (probably most therapods) would have been not much different from modern birds. Ones with scales (the rest, based on skin imprints from a few different groups) would have been a bit tougher. Ones with armor (the ankylosaurs) may very well have been bulletproof, but a... | [
"We don't actually know what the skin of dinosaurs looked like or was made of. Because skin is an organic material it decomposes away, so humans have never seen dinosaur skin.",
"We can guestimate the properties of the skin based on environment, but the color of a dinosaurs skin is really up to the designer of th... |
[
"So when we say the \"speed of light\" we are referring to a measurement that approximates an asymptotic value that cannot be physically measured?"
] | [
false
] | If a particle has mass, its velocity can never be the speed of light unless its Energy is infinite. Since light has mass, what is the deal? Light can't travel as fast than its own self? We are just approximating an asymptotic value we can't actually measure in the universe since everything has mass right? | [
"While light has mass-energy, it has no rest-mass...in a certain sense all of its energy is \"kinetic\" (although that's not exactly accurate).",
"Light does move at the speed of light. All photons--indeed all particles with zero rest mass--always move at the speed of light, never slower.",
"The fact that ligh... | [
"Light ",
" at a speed less than c. It hits a particle in the medium, then gets re-transmitted. This makes its overall speed a little slower. This is my understanding of it, at least."
] | [
"Light ",
" at a speed less than c. It hits a particle in the medium, then gets re-transmitted. This makes its overall speed a little slower. This is my understanding of it, at least."
] |
[
"What happens to dead germs or bacteria?"
] | [
false
] | [deleted] | [
"Inside the body: macrophages eat them. (Sort of, dead bacteria, virus, fungus etc are destroyed by the immune system)",
"Outside the body: If you use hand sanitiser, germs will dry up and probably stick to the skin until it's rubbed off or you wash your hands. If you wash your hands with soap and water, the soap... | [
"Most will just dessicate or dry up. However this is also depended on what kind of bacteria we are talking about. Some bacteria will have a special capsule, allowing them to survive in very adverse conditions. ",
"But in your cause the rubbing alcohol would cause most of the water in the bacteria to migrate out... | [
"I wasn't broken up over it or anything, but thanks for the explanation. I read Reddit from the front page, so I don't usually notice any sub-rules in the sub-reddits. I'll mind my manners in AskScience from here on out."
] |
[
"What are the funding agencies that fund \"risky\" research?"
] | [
false
] | I found to be very interesting, so I know that HHMI is the one that funds risky biomedical research But what about other organizations that fund research, in say, fields like the geosciences or astrophysics? | [
"Its just a front for the stargate program :P"
] | [
"DARPA",
" actually funds a lot of weird stuff."
] | [
"Scary bit: The Air Force runs a space program bigger than NASA. "
] |
[
"How does satelite radio differ from fm or am? I can easily build a radio at home for am/fm but whats stopping me from making something that picks up satelite?"
] | [
false
] | [deleted] | [
"There isn't a technical reason why you couldn't build a device that receives signals from satellite radio providers - it's typically broadcast in the S band range, like a number of common consumer devices like garage door openers and wifi routers.",
"However, AM/FM radio broadcasts are intended to be heard as br... | [
"Protecting broadcasts which are sent to large numbers of people is really hard. They all have to have copies of the decryption key buried somewhere inside their device. This means that breaking the mathematical part of the encryption is not necessary; all that's needed is to figure out how to extract the keys fr... | [
"If it was easy, then the encryption wouldn't be very good. Going into depth about it would be better served by its own question, but the gist is that encryption relies on the fact it can be very easy to transform numbers in one direction and very difficult in the other. Like say 11 * 13, you can do that in your he... |
[
"AskScience AMA Series: I'm Will Armentrout, an astronomer at the Green Bank Observatory in the heart of the US National Radio Quiet Zone. Ask me anything!"
] | [
false
] | I'm Will Armentrout, an astronomer at the Green Bank Observatory ( ) in West Virginia. The Observatory is within the United States National Radio Quiet Zone, a 13,000 square mile area of the Appalachian mountains where radio transmissions are limited by federal and state law. These protections become more restrictive a... | [
"I really think there will always be a place for large single-dish observatories, and the reason is that while interferometers can be fantastic instruments and get you exceptional resolution (the best resolution of any telescopes at any wavelength), there are things interferometers are not inherently good at.",
"... | [
"Any time I can see a clear view of the Milky Way strewn across the sky, I get a little misty eyed. Green Bank was picked as a place that would be good for a radio observatory (protected by the mountains from radio interference from nearby cities), but it would not be the best place for an optical observatory. Thos... | [
"Do you know how the size and restrictions of the National Radio Quiet Zone were determined? Do other observatories have areas of similar restriction?"
] |
[
"Really odd one, but can humans produce sounds that they cannot hear? So above the Hz that a human can hear but a cat, for example, could?"
] | [
false
] | null | [
"\"In 2012, Storms reclaimed the record for the Lowest Note Produced by a Human. The new record is G−7, or 0.189 Hz, eight octaves below the lowest G on the piano, or just over seven octaves below the piano.[5] The most recent published record is in the 2020 Guinness Book of World Records.\nStorms' record-setting s... | [
"That article says it would take about 5 seconds to complete one oscillation of the vocal cords at that lowest pitch. Which is, let’s say, really implausible."
] | [
"A sound wave is a wave. It has an oscillating pattern and this one happens to take 5 seconds to complete an oscillation."
] |
[
"How common are viral & bacterial infections among aquatic organisms?"
] | [
false
] | Have there been any infectious diseases that have devastated entire populations/communities? | [
"Infections are common among all organisms. One good example is Vibrio cholerae, the bacteria that causes the disease cholera. It's natural habitat is shellfish. ",
"http://en.wikipedia.org/wiki/Vibrio_cholerae",
". This sort of behavior is a HUGE driving force for evolution. And for fun I leave a link abo... | [
"Thanks. We learned about infections in biology class, but we only went over land animals."
] | [
"Another fun fact. There are 22000 genes in the human body. Recently scientists looked at the bacterial species in and on our bodies and found 8000000 different genes. Pretty crazy."
] |
[
"What happens to the 0.01% of bacteria that isnt killed by wipes/cleaners? Are they injured or disabled?"
] | [
false
] | | [
"Ok, so I work in the industry of antimicrobial testing, and no, it's not a legal disclaimer, we test and see how much of a log reduction a product gets and we literally scrub the shit out of the device or surface or whatever, so no, it's not a CYA claim, it is based on actual FDA or EPA regulated testing on very s... | [
"There's also the ",
"minimum infective dose",
" to take into consideration. Let's say you're about to eat a sandwich and you've just washed your hands. If it takes 40 E. coli to infect you and washing your hands killed all but 10, you're likely to not be infected."
] | [
"The 0.01% form spores or slime layers that are resistant to alcohols and detergents that are in the wipes. The purpose of the chemicals is to destroy bacterial cell walls. However, if the germ has a protective layer, it can remain on surfaces until it enters a more favorable environment. Not to mention, when the c... |
[
"Why does closing one eye help the pain when it's really bright out?"
] | [
false
] | Shouldn't it be equally bright in each eye? | [
"You \"feel\" bright light when the iris contracts and makes your pupils small. This is why photophobia is a common symptom of corneal abrasion and viral keratitis, and why browache results from pilocarpine drops that force the pupil to shrink.",
"When you cover one eye, you reduce the stimulus to pupil constrict... | [
"So, ",
"u/mckulty",
" is probably wrong, but it's OK, because this was a leading hypothesis for awhile, and there was no satisfactory explanation for photophobia until ~2006. The conceptually easiest way to show this is the following case report:",
"http://www.ncbi.nlm.nih.gov/pubmed/17121141",
" ",
"Whe... | [
"Ah.. the pupil isn't the only light control in human eyes. The retina itself is responsible for night vision; in dim light your retina gets more sensitive like raising the ISO on film or a digital camera. This would happen with one eye closed, or patched, no matter what happens in the other eye. ",
"Shining ligh... |
[
"Is there a specific medical reason why 4 hours is the cutoff time to see a doctor after ED drug's effects won't go away?"
] | [
false
] | Or is there some arbitrariness to it? | [
"The reason being is the blood will clot and you might lose it.., the solution to this is 2 needles that are place on either side of the urtheral opening to drain the corpus cavernosum.",
"http://en.wikipedia.org/wiki/Corpus_cavernosum_penis",
"I have seen a few people come to the ER for it, each time it was re... | [
"Current scientific evidence demonstrates that when an erection lasts longer than 4 hours, it merits evaluation and possible treatment because of the potential detrimental effects of the erection on the viability and future function of the corporal tissue.",
"There is some \"arbitrariness\" to it, although starti... | [
"Greetings fellow science seekers! It's great if your friend's friend's uncle's cousin had some kind of issue with having an erection last longer than safe. However, this is a place for science instead of anecdotes. Unless you have relevant, expert knowledge on this subject, could you please keep it in your pants? ... |
[
"A thin girl from my hometown gained ~150 pounds in about 1 year. How is this possible?"
] | [
false
] | null | [
"It's difficult to answer questions about individual anecdotes without resorting to speculation which we try to avoid."
] | [
"I was just wondering which medical conditions may result in rapid weight gain or if it's even possible to gain so much weight so quickly on her own accord. "
] | [
"So a more general question like \"are there medical conditions that can cause a rapid amount of weight gain in a short period of time\" would be totally fine. But asking about a particular person is impossible to answer objectively over the internet. "
] |
[
"Why do infections not spread and kill us today, but seemingly killed often in the past?"
] | [
false
] | null | [
"Medicine"
] | [
"Medicine"
] | [
"Medicine like antibiotics, knowledge about cleaning wounds, hospital care if things get bad / fever persists."
] |
[
"Does Mercury experience any significant tidal forces from Sun?"
] | [
false
] | null | [
"Yes, though the tidal forces aren't strong enough to cause a full tidal lock. Instead Mercury is in a 3:2 orbital resonance with the Sun, meaning that three days on Mercury are equivalent to two full orbits around the Sun.",
"Solar tidal forces are relevant even on Earth: The solar tide is about half the magnitu... | [
"The solar tide is about half the magnitude of the lunar tide (but much longer period)",
"The period is nearly the same, both are driven by the rotation of Earth. The time between the Sun at the same position in the sky is a bit shorter than the period between the Moon at the same position, but that difference is... | [
"The orbit is fairly regular. It is not closed - its perihelion precesses. 90% of this precession comes from the gravitational influence of other planets, which can be described with Newtonian mechanics. Only 10% is an effect of general relativity that doesn't exist in Newtonian mechanics."
] |
[
"Why are the wheels of NASA's Mars rover, Curiosity, wearing out?"
] | [
false
] | After reading an article from Pasadena News: ...I got to wondering why Curiosity's wheels are wearing out and what threat punctures are to a non-inflated solid aluminum wheel? I've never heard this discussion from any of the other rover camps. Is it because of Curiosity's greater mass? Harsh terrain of the area it's ex... | [
"Here are some photos in case anyone was wondering. ",
"http://mars.jpl.nasa.gov/msl-raw-images/msss/00490/mhli/0490MH0262000003E1_DXXX.jpg",
"http://mars.jpl.nasa.gov/msl-raw-images/msss/00490/mhli/0490MH0262000001E1_DXXX.jpg",
"http://mars.jpl.nasa.gov/msl-raw-images/msss/00494/mcam/0494ML1964004000E1_DXXX.... | [
"This topic has been discussed multiple times on other subs. That aluminum that's cracking is probably about the thickness of a cola can. This wear was expected and is largely cosmetic. "
] | [
"This topic has been discussed multiple times on other subs. That aluminum that's cracking is probably about the thickness of a cola can. This wear was expected and is largely cosmetic. "
] |
[
"Why does a fan make me cooler instead of hotter?"
] | [
false
] | [deleted] | [
"In principle, you are correct. However, oxygen moves at something like 443m/s. The small amount of extra speed you are giving the atoms isn't particularly consequential. Really, the fan just ends up directing more of the molecules past you.",
"Overall, like was mentioned before, this has the effect of constantly... | [
"In principle, you are correct. However, oxygen moves at something like 443m/s. The small amount of extra speed you are giving the atoms isn't particularly consequential. Really, the fan just ends up directing more of the molecules past you.",
"Overall, like was mentioned before, this has the effect of constantly... | [
"Right. Taking a molecular view of things, the speed of air molecules due to Brownian motion is much greater than the speed they gain due to the fan, and so the fan doesn't increase the temperature of the air much at all. Since the air is cooler than you, when air molecules collide with your \"skin molecules\" th... |
[
"Is air really invisible or have we evolved to not detect it's would-be colour?"
] | [
false
] | Does it simply not reflect light or have we evolved to not detect it since it would impede our vision. If it really doesn't have a colour, would it be possible for human's to evolve with visual organs that would adapt to another atmosphere that's more opaque? | [
"You can look at ",
"this chart",
" which shows the amount of light of various wavelengths.",
"The blackbody spectrum is the approximate colour of sunlight. By the time the light reaches sea level, you get the line shown by the red blocks. It seems substantial, but remember, the atmosphere is many kilometres ... | [
"Air does not interact significantly with any significantly sized band of light frequency. For example, if we had X-ray vision sight and there was ample X-ray light, we would see air still as transparent. However, as you probably know, X-rays are absorbed by very dense materials like bone and metal, but now flesh a... | [
"Since human eyes are only developed to see visible light spectra Red to Violet this really impacts the question. Air up close is clear, but in a distance we see the mixture of gasses and particles as faint or brilliant colors. ",
"So the answer could possibly be that we haven't evolved, but there isn't a way tha... |
[
"Why do Aurorae in the Northern Hemisphere seem more prevalent in the winter?"
] | [
false
] | EDIT: Answered! A simple matter of better observation opportunities. ...or is this just my perception? Does axial tilt affect aurora intensity? I do understand that we're just passing sunspot peak right now, but I've not seen much in my 45º latitude. I can, however, remember winter shows from years gone by that reached... | [
"Northern latitudes get little sunlight in the winter. At the U.S./Canadian border (49°N) the nights are 16 hours long around the winter solstice. It is merely the perception because observers have significantly longer nights in winter than summer in those latitudes."
] | [
"The aurora intensity actually peaks ",
"during the spring and fall",
". During the equinoxes the Earth's magnetic field links up with the interplanetary magnetic field, which can partially cancel Earth's magnetic field at the point of contact - triggering auroras.",
"However, since the auroras are a daily o... | [
"Aurora can only be seen at night. the resulting longer days of spring and summer simply limit the available opportunity to view the phenomenon. "
] |
[
"If you lived on a high-gravity planet would you develop super-strong bones and muscles? Would you be able to jump off tall Earth buildings without injury?"
] | [
false
] | null | [
"You would develop stronger muscles and bones, much like a weightlifter does, but nothing superhuman. You'd also wind up being a lot heavier, which would counteract much of your gain in strength. Top jumping athletes develop the muscles they need for jumping...you'd be developing all of your muscles.",
"In addi... | [
"I don't see that question. I see a question about whether he could jump off a tall building, but not if he could jump high"
] | [
"I don't see that question. I see a question about whether he could jump off a tall building, but not if he could jump high"
] |
[
"Ask Anything Wednesday - Engineering, Mathematics, Computer Science"
] | [
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! ... | [
"How does the most basic level of a computer's hardware/software relationship work -- How does a motherboard and CPU essentially consisting of a lot of binary switches and pathways between them actually run software?",
"I'm familiar with the concept of the motherboard having a machine language instruction set tha... | [
"When a program is compiled, it is essentially compiled into a long list of instructions. Each instruction is just a sequence of bits, typically between 8 and 64 bits.",
"In the real world, a CPU distinguishes between registers and memory. You can think of registers as a very small but super-fast internal CPU mem... | [
"Codecademy",
" is geared toward any level of competency. Pick a thing you want to be able to do (make a website, write code, whatever), and go for it."
] |
[
"Is there a limit to the number of planets that can plausibly form around star systems of two or more stars?"
] | [
false
] | null | [
"It depends on how closely the stars orbit each other. ",
"There are three types of possible orbits for planets in a binary star system: ",
"Planet orbits around Star A",
"Planet orbits around Star B",
"Planet orbits around the gravitational centre of Stars A and B",
"In cases 1 and 2, the upper limit for... | [
"Over the long term, probably not. Even slight perturbations in its orbit from either of the two stars, or another planet in the system, or even more moderate gravitational influences would inevitably destabilise an orbit like that, and its orbit would end up with a collision with one star or the other (or ejected ... | [
"Could there be a stable system where a planet orbits first star A and then star B in an ∞-like fashion?"
] |
[
"Audio Duration vs. Data Usage on CDs? Explanation?"
] | [
false
] | When burning a CD, why does is duration the only thing that matters instead of data used. I can burn a 72 minute FLAC audio file or a 72minute 128kbps MP3 file on the same CD, why is this? | [
"Because whatever your source file audio is, it gets converted to CD-Audio format to go on the CD, which is a fixed sample rate. So 72 minutes is 72 minutes however you slice it. "
] | [
"Audio is stored on a CD in a fixed format, which varies in some important ways from the format that is used to store data on a CD. The typical format for audio CDs is referred to as ",
"Red Book",
", and fixes several parameters which control how large the data is on the CD. First, the audio is encoded as ster... | [
"A friend of mine had an old car CD player with a switch that expanded either the left or right channel across both speakers. In exchange for mono sound (which doesn't matter in a car) he could record twice as much audio onto a CD as long as he remembered to change the switch to chose the 'side' of the CD."
] |
[
"Tobacco plants have been genetically altered and are now 40% more productive. How can such an old evolutionary process as photosynthesis be inefficient?"
] | [
false
] | If I understand this paper* correctly, it is said that photosynthesis in C3 plants is really inefficient. Specifically the photorespiration part where carbon is transformed in CO2 again. Scientists see this as a waste of energy, and it has now been improved by constructing "a metabolic pathway in transgenic tobacco pla... | [
"Evolutionary processes do not arrive at the best solutions, only ones that work well enough to propagate. Perhaps there are other limiting factors that made more efficient photosynthesis less fit for survival, such as nutrient depletion. This is, in fact, a problem with modern engineered crops which require chemic... | [
"The only way to be sure that the process is inefficient is to prove that it can be significantly improved on. Biochemists can have the insight that it may be inefficient, but really, there's no other way to know than to effectively improve it. And then to prove that there's no catch with the improvement, and peopl... | [
"Photosynthesis has one of the least efficient enzymes on earth, known as RuBisCo, and can only do several reactions a second, while many are able to carry out there processes 1000's of times per second. I'm betting this is the enzyme they tried to optimize. It also has a tendency to fix oxygen molecules instead of... |
[
"Why can't we produce energy by fusion when we have working fusion bombs?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):"
] | [
"What is the flawed premise?"
] | [
"We can produce energy from fusion in reactors, just not yet more than is put in to operate the reactor. And furthermore bombs and reactors (particularly magnetic confinement) are totally different physical problems, so being able to do one doesn't imply that we should be able to do the other."
] |
[
"Why does working memory have a limited capacity?"
] | [
false
] | Why can we only think of a few things at once? | [
"I don't think that's quite the same question. I think Noxzer answered appropriately. Capacity with working memory would be a matter of how much can be held at one time. Capacity with attention would be a matter of \"bandwidth\": how much information can be received at once. There's a subtle difference. But be... | [
"Good question, it actually has to do with attention.",
"There are a few working memory models out there, but one of the most widely used is the ",
"Time-Based Resource Sharing Model",
". Essentially what it says is that, in order to keep something in working memory, we need to keep refreshing the representat... | [
"So you're simply changing the question to 'why does our attention have a limited capacity'. "
] |
[
"Heparin consists of a HUGE chain of molecules, so how can there be gel forms to treat swelling and hematoma? If it does, how exactly does it penetrate the skin. (Or if it doesn't penetrate the skin, but still works somehow)."
] | [
false
] | My other question would also be: In the professional field here in germany, Herparin is, besides swelling and sports injuries recommended to accelerate the healing of hematomas. But isn't it contraproductive to what the body is trying to do? I haven't found an explanation how it should work. But in germany something wo... | [
"When you have a hematoma, the thing \"the body is trying to do\" is already over. ",
"A hematoma is just an area of blood that leaked out of a broken blood vessel. Once clotting occurs and the vessel has healed itself, you still have this blob of blood sitting there in the tissue. That's what a hematoma is. It d... | [
"Hey Guys! Friendly neighborhood mod here. This is a great question, but let's not focus on the whole \"Homeopathic remedies\" part of this question. We're not here to debate that. We're here to talk about heparin!",
"Cheers!"
] | [
"I believe the heparin found in gel forms are usually low molecular weight forms so they should penetrate the skin more easily.",
"Heparin is capable of binding to histamine which sequesters it from triggering the inflammatory response. Among other things, histamine causes vasodilation and increases the permeabil... |
[
"Since we measure nuclear warhead yields in terms of tonnes of TNT, would detonating an equivalent amount of TNT actually produce a similar explosion in terms of size, temperature, blast wave etc?"
] | [
false
] | Follow up question, how big would a Tzar Bomba size pile of TNT be? (50 megatons) | [
"Assuming a density >1 g/cc the volume of 50 megatons of TNT is on the order of 300x300x300 meters",
" \nThe initial conditions of the blast are quite different because the fusion event occurs in a much smaller volume and hence temperature and energy density are greater-initially. Thus the initial shockwave is fa... | [
"This was super informative. Thanks!",
"Here are a couple quick youtube videos I found in case anyone else wants to see them.",
"https://www.youtube.com/watch?v=BGE9KSlHmO0",
"https://www.youtube.com/watch?v=arQMBGdxIfw"
] | [
"It would release the same amount of ",
" (that's what tonnage equivalent means) but the devil is in the details. Conventional explosives release mostly mechanical energy and some heat; a nuke releases a bigger share of heat and a lot of ionizing radiation."
] |
[
"Does a rocket continue to accelerate if it has reached the velocity at which gas escapes its nozzle?"
] | [
false
] | [deleted] | [
"The exhaust gases move in a more or less constant velocity, with respect to its source, not the ground. A rocket with isp of 300 (exhaust velocity 2940m/s) will have exhaust of 2940m/s regardless of its speed, and as such, the force will be the same (but still dependant on throttle, air pressure, etc)."
] | [
"Almost correct: it's not the speed that matters, but the ",
". The gases will accelerate from zero to exit velocity, and like you said this is relative to the source, not the ground. That means there's a net force on those gases in the direction of the nozzle. Newton's third law applies, so the rocket will under... | [
"Actually both comments are equivalent. There is a fixed distance from the combustion chamber to the nozzle's exit, so the exit velocity is determined by the acceleration.",
"In most equations about rockets only exhaust speed is taken into account, including the most famous (and probably the most useful) one, the... |
[
"Exactly how does not finishing a course of antibiotics produce resistant bacteria? If a resistant population develops, wouldn't that population survive the entire course anyway?"
] | [
false
] | Always wondered exactly how this happens, even though I've learned THAT it happens in several classes. | [
"Resistance is not binary, i.e resistant/not resistant. If you do not kill all the bacteria, the ones hat are left are the ones that are a bit more resistant than the ones who died. Repeat that cycle enough times and you have a degree of resistance that makes it difficult to treat with normal doses of antibiotics."... | [
"Bacteria reproduce very quickly, and mutate very often, and even swap genes amongst themselves. So they are constantly changing in tiny ways, which may effect how they react to antibiotics. ",
"Generally you do not get a bacteria that has mutated to be instantly immune to an antibiotic. Random mutations are not ... | [
"Additionally, even if there are a few strongly resistant individuals after completing the course, the immune system will have a much better chance of finishing them off if the last of the antibiotics nukes as many others as possible."
] |
[
"In string theory, what exactly is meant by the notion of \"other universes\"?"
] | [
false
] | I understand that in order for the mathematics of string theory to work out, it calls for 10 spatial dimensions, plus time. Why would the existence of additional spatial dimensions imply the existence of other/parallel "universes"? Or rather, what is really meant when that language is used? I see terms like "parallel u... | [
"So there's a couple of things overlain here. ",
"First, string theory posits the idea of additional ",
" dimensions. This means the furthest you can travel along these dimensions is some very small distance (like 10",
" m or smaller) before you're back where you started. It's more about opening up different ... | [
"Yeah, it's not exactly a hierarchy, ",
". It's more like... the classic flatland example. Suppose you were a flatlander, confined to only 2 dimensions. there may be third dimensions and so on... but you, yourself, by the laws that govern you, are stuck where you are. ",
"And sometimes maybe a 3D thing casts a ... | [
"Wow, thank you for the answer! ",
"So if I understand this correctly, string theory calls for these 10 spatial dimensions- 7 that only exist below Planck scale, and then 3 that we're familiar with that exist above that scale and in which particles move about and interact. Now this membrane theory assumes that ab... |
[
"How do brain regions actually communicate together?"
] | [
false
] | This seems like it has a pretty obvious answer, but I couldn't really truly find any information on it without making my own guesses. To be clear, I mean 2 things by 'communicate'. First a synapse from the front region of the brain to the region at the back of the brain, just seems too expensive to be developing. Hence... | [
"oh man... I'm still functionally a student, but this might be my first ever askscience question I have something to contribute to.",
"First, when you say 'a synapse from the front region to the back would be too expensive', you're meaning something else than what you're saying. A synapse is very, very small (20-... | [
"This is an amazingly clear answer thanks. ",
"I will definitely check through the Kandel book and Stones neural information theory. I also looked at the links, its so very interesting. ",
"I also indeed meant more of a neural circuit or large scale brain network with my reference to synapse."
] | [
"I agree, the brain is an incredibly fascinating topic. My actual area of research is artificial intelligence, and there are some incredible connections between the fields... I'm just self studying my way up into neural science, and it's really surprising where things are going, and how much we currently understand... |
[
"Today, a brilliant white turkey vulture landed in my yard. Anybody care to expound on how rare this bird might be?"
] | [
false
] | Here's a few pictures I managed to get before it left: According to they are rare, but I believe they may be talking about albino birds. It looked a little ragged in person. It was a little wobbly and looked like it was having trouble flying and staying up. But what little I've read about albino birds is that they tend... | [
"As I understand albinism, it is more common the more inbred something is. So if the area it came from has few breeding options, its commonality goes up per capita. If this species is in decline I would imagine it will become more and more common until it becomes extinct. "
] | [
"If this species is in decline I would imagine it will become more and more common until it becomes extinct.",
"Turkey vultures are the pigeons of carrion-eaters. They're not dying out any time soon."
] | [
"And ducks don't have 5ft wingspans."
] |
[
"Why don't we measure food energy in Joules?"
] | [
false
] | null | [
"Food energy ",
" measured in kilojoules in New Zealand where I live, occasionally also with calories in brackets. I suspect it's the same in all countries that use the metric system.",
"Fun fact: Calorie values given on food packaging are actually kilocalories. The kilo is dropped for some reason."
] | [
"It's cultural. You can find many other instances where energy is measured in other units, and it's all cultural. One reason this happens so often is that energy is connected to so many different processes. In some cases, we're interested in the connection to thermal energy, and we've made units to reflect that.... | [
"The unit of energy in the International System of Units (SI) is the joule \n(J). This is the accepted standard unit of energy used in human energetics and it should also be used for the expression of energy in foods. Because nutritionists and food scientists are concerned with large amounts of energy, they general... |
[
"Demonstrations of natural frequencies"
] | [
false
] | Physics question, specifically about waves. I am afraid this will be incoherent because of my lack of related vocabulary but here it goes: I have seen various demonstrations of natural frequencies in videos and am looking for a way to recreate what I have seen. One of the methods I was shown demonstrated used a flatt... | [
"A pretty simple way to do something similar to what you are talking about is to use a speaker where you can control its frequency and put a dish of water on top of it. ",
"Video"
] | [
"It's easy to experience a 3d version of this. Get some low frequency pure sine tones and play them back through a speaker in a medium to largish space. Walk slowly around the room and experience the sound go up and down in volume (in fact there will be places where you can't hear the sound at all and they will cha... | [
"Maybe it's not so good visually, but if you have access to a guitar or other stretched string, you can play around with its natural frequencies."
] |
[
"Why the plume of steam when boiling water is removed from heat?"
] | [
false
] | Chemistry question- When a pot of boiling water is removed from a heat source (gas range burner), there is a plume of steam as the boiling subsides. What is the cause of this plume? Wouldn't the vaporization slow down/stop after being removed from heat as opposed to increasing temporarily? | [
"What you see is condensed water vapour - you can't easily see steam or gaseous water vapour. So what you're observing isn't the rate of vaporization - in fact, the vaporization doesn't increase. What changed when you moved the pot is the temperature of the air immediately above it - because it's cooler, more water... | [
"Steam is invisible. What you see is condensed water. The plume you see is condensate, coinciding with the removal of heat."
] | [
"Thanks Rupert!"
] |
[
"Is it possible for any object to have no motion or momentum?"
] | [
false
] | null | [
"For each massive particle, there is a frame in which that particle is at rest."
] | [
"Ok, now how does that work in practice.\nDoes that mean the massive particle is stationary in relation to the entire rest of the universe?"
] | [
"Ok, now how does that work in practice.\nDoes that mean the massive particle is stationary in relation to the entire rest of the universe?"
] |
[
"What is the ringing noise you hear when it's very quiet?"
] | [
false
] | [deleted] | [
"/r/tinnitus"
] | [
"While tinnitus is \"a ringing noise\", it's not necessarily \"the ringing noise when it's very quiet\". It really depends on how quiet OP is able to achieve. In a really quiet environment you can hear your own blood flow. With increase of blood pressure, the sound of blood flow will have a higher pitch, and, modul... | [
"Not a scientific source, but it is mentioned in John Cage's book ",
" that he asked the technician of a sensory deprivation tank what the source of a low hum and high-pitched whine were that became audible after several hours. The technician responded that the hum was his circulation, the whine his nervous syste... |
[
"I heard Phytoplankton contributes more oxygen than trees themselves, is this true?"
] | [
false
] | I heard this from a friend and could hardly believe it, I was curious (not being a big science guy) that if this was a true fact or not. | [
"Remembering that 3/4 of the earth's surface is covered with water, you have a much greater potential area for photosynthesis. ",
"Bonus fact: While we often refer to crude oil as coming from dinosaurs, most of our oil is also from ancient phytoplankton."
] | [
"That is what I said. We are in agreement. "
] | [
"This is a misconception. The ocean only appears blue because that is the last wavelength of light to be filtered out. Phytoplankton are microscopic, so it would take an absolutely absurd number of them to turn the ocean green. In cases where this happens, it is usually an indicator of pollution, and it is not m... |
[
"Besides the current monotremes, marsupials and placentals, have there ever been other different types of mammals?"
] | [
false
] | If the answer is yes, how many were there? Do we know how they reproduced? What made them different from the still extant ones? | [
"That depends on how you mean it. Were there other mechanisms of reproduction than egg-laying, marsupial or placental? No. Egg-laying is the ancestral trait, and everything that came before the marsupials laid eggs. ",
"Were there other types of mammals? Yes. We think of the monotremes as being the only egg-layin... | [
"Thanks for the reply! ",
"What traits did those extinct mammals have that made them different from the current ones?"
] | [
"I can't give you a really complete answer to that, but a big part of it is their teeth. "
] |
[
"Does a water/ethanol mixture in a pressure cooker release relatively more ethanol with steam release? Is the maximum pressure reduced?"
] | [
false
] | gave rise to the question how a reasonable mixture of ethanol and water (say 1:9) would behave if cooked in a pressure cooker. While ethanol boils at a lower temperature than water, a pressure cooker usually reaches a much higher temperature than both liquids' boiling point. On the other hand, ethanol has a higher vapo... | [
"Water and ethanol form an azeotrope that boils at a lower temperature than either pure water or pure ethanol. When you boil off any mixture of ethanol and water, the mass percentage in the vapor will tend to be closer to that azeotropic mixture than is the liquid you're boiling. That is how liquor is distilled, up... | [
"When looking at this a few years ago, I had a hard time finding vapor pressure diagrams for ethanol/water solutions at pressures higher than atmospheric, but the takeaway I remember is that the azeotope comes at a lower percentage ethanol at higher pressures.",
"Pressure swing distillation takes advantage of the... | [
"Same as if you'd just used water: some of the vapor will escape during heating and during cooling and some more when you open the cooker after the pressure drops but pressure cookers are designed to retain liquid so you don't lose much."
] |
[
"Is there a way to determine the color of something without using light?"
] | [
true
] | [deleted] | [
"Something similar has been ",
"asked before",
".",
"In short, yes it's possible to calculate via quantum mechanics, but it's really much easier to just find a way to take a colour photograph."
] | [
"If you look at a single molecule, you can attempt to find its colour by calculating the absorption energies of its molecular orbitals. This is what dictates what wavelength of light a molecule absorbs light.",
"However, once we get into a ",
" of molecules, we get other effects. Quantum electrodynamics, for ex... | [
"If you look at a single molecule, you can attempt to find its colour by calculating the absorption energies of its molecular orbitals. This is what dictates what wavelength of light a molecule absorbs light.",
"However, once we get into a ",
" of molecules, we get other effects. Quantum electrodynamics, for ex... |
[
"Where does the buoyant force come from if an object is at the bottom of a body of liquid? And does the buoyant force act more weakly on flatter objects?"
] | [
false
] | Suppose I take a block of wood and push it to the bottom of a bucket of water. When I let go of the block it will float to the top, clearly due to the buoyant force acting upon it. However, at the moment I let go of the block there are no water molecules beneath it to help push it upward. My intuition says that maybe i... | [
"If there is very little space between the block and the bottom of the bucket, you may notice a suction effect keeping the block of wood down there for a few parts of a second, or more. If there is truly no space between the block and the bucket bottom, it would stay stuck down got a long time, maybe indefinitely."... | [
"What des is getting at is that its not feasible to place the block on the bottom with no water underneath, and if it were it would indeed suction to the bottom. The sides have nothing to do with it (assuming they are parallel. ",
"And as for your third paragraph, the buoyant force relies soley on the volume of t... | [
"Indeed. This is how stricken submarines get trapped at the bottom of the ocean. They settle on the bottom, settle into the sediment, and even if they blow the tanks to make the submarine bouyant, it may not always be sufficient to overcome the suction."
] |
[
"Can a gas be more concentrated when dissolved in water than when it's in the atmosphere?"
] | [
false
] | The molarity of a gas at STP is 22.4 moles per liter. Are there any gases that can exceed 22.4M when aqueous? If not, can you raise temperature or [lower] pressure to make molarity greater than gaseous concentration before the solution evaporates? | [
"Not exactly the same thing, but a liter of gasoline has more hydrogen in it than a liter of liquid hydrogen. Liquid H2 has a very low density due to some interesting quantum effects, and the dense bonding of hydrogen to carbon actually stores more hydrogen than pure hydrogen!"
] | [
"Okay, first things first you have this backwards: ",
"The molarity of a gas at STP is 22.4 moles per liter. ",
"This should, perhaps, with some thought, seem unreasonably large to you.",
"What you're thinking of is that 1 mol of a gas takes up 22.4 liters at STP. So the molarity is 1 mol/22.4 L = 0.045 M! ... | [
"Henry's law can answer this; it is of the form \np = k x c, where k is the Henry's law constant of a specific solute, p is the partial pressure of the solute and c is the concentration in water. For c > p x 0,045 M x atm, p/k>p x 0,045M x atm <=> 1/k>0,045M x atm <=> k<22,2 l x atm/mol for a specific solute in a s... |
[
"In biology how do ligands find their receptors physically? Do they just float around randomly and if they hit the receptor at the right angle they bind?"
] | [
false
] | For example, with antibodies, do they just float around the blood at a certain concentration and when they collide with the epitope of their corresponding antigen, they attach? I know its like a lock and key analogy, but textbooks just show a 2d image with an antibody falling ontop of an antigen. In actuality, is there... | [
"That's correct, up until they're extremely close they're just diffusing around.",
"That might seem like it would take a while, but diffusion works with different speed on different scales. We can estimate the instantaneous velocity of a protein in water to be around 10 m/s, its thermal velocity. That doesn't sou... | [
"This really helped me visualize it. Before, I was imagining individual sand particles trying to fit into a groove that matches its geometric complementary shape"
] | [
"Remember, everything inside your body is constantly surrounded by water. But at this scale, that really means that it is constantly being bashed into by baseballs thrown from every direction at hundreds of m/s. There's a ",
" of energy in room temperature water, and you can see this in the diffusion of macromole... |
[
"Why do video chat services, e.g. Skype, decrease in quality when the camera is moving?"
] | [
false
] | I have noticed when I chat on Skype, Facetime, or Gchat that the video quality significantly decreases when the camera is in motion. What about the video compression makes this such a tech hurdle? | [
"This is not my area, but as I understand it, instead of transmitting the entire frame 30 times per second (or whatever), the software basically says \"these pixels all stayed the same, and I'm sending you the new information for these other pixels\". When the camera moves, obviously you're having to update a lot ... | [
"/r/smeghead333",
" is correct, the compression algorithm generally sends \"key frames\" which are the entire camera area, and then following the keyframes only the delta (change) is sent, ie only the areas that are changing like your face talking.",
"When you move the camera around, it has to send more keyfram... | [
"To add on to what the others have said, it's less about movement than it is overall change, a movement changes the scene a lot making it harder for the algorithm to guess and place things, bring up the bitrate on a bd disc and you'll see this. But a movement isn't as harsh as something where the compressor just c... |
[
"Is there a rule of thumb for maximizing the magnetic field when making a solenoid?"
] | [
false
] | As a physicist I'm a bit embarrassed asking this, but this is something I've never "gotten." I know all about how to calculate the B-field in a solenoid, but in a practical sense I'm not sure how I would go about designing one if I want the most bang for my voltage source. For example, suppose I have a 12 V car battery... | [
"Sure, I could go ahead and work it all out, making some really complicated formulas ",
"It shouldn't be that complicated. The resistance per length of the wire is R/L = ρ/A, where A is πR",
" . The length of wire being used is 2πR*N, where N is the number of loops, so the resistance of the solenoid will be R =... | [
"Yes, it's a tradeoff between the two. That's why you pick a starting point that seems reasonable and iterate the design from there."
] | [
"If we ignore the thermal wattage, then we've eliminated the whole problem!",
":)",
"Just design for 10KW, or 100KW, or whatever you want. If the field is too weak, then simply design for ",
"On the other hand, for real-world engineering, wattage is the primary variable, since we require that the solenoid n... |
[
"Do animals besides humans have types of blood such as A, O-, etc.?"
] | [
false
] | [deleted] | [
"I think ",
"this",
" is what you are looking for"
] | [
"Yes, in fact we have a pretty conservative blood type grouping of just 8 combinations (ABO and +/- combined) where as horses have 10, cattle have 11 and dogs have an impressive 13. Although in cattle the B group has 60 different antigens so I think they win the non-human blood group diversity prize."
] | [
"Animals do have blood types, but the specific antigens differ. The blood type antigens are specific molecules on the surface of the red blood cells which determine \"blood type.\" When our body sees antigens it doesn't recognize, it attacks the blood cells. That's why we want a transfusion of blood with the same t... |
[
"How long after clinical death, can someone be revived?"
] | [
false
] | How long without damage to the body (brain, heart, etc.)? And how long before being unable to keep yourself alive (breathing by yourself, without help)? | [
"The movies make it look like if the patient hasn't come back in 1 minute, then it's over.",
"Remember that most things in movies are unrealistic. The medical staff call it after 1 minute because a 20-minute-long scene of someone giving CPR would be very boring.",
"EDIT: punctuation"
] | [
"It’s quite variable, but even with good CPR and return of spontaneous circulation after only a few minutes people can have quite significant hypoxic brain injuries. If you’ve been having CPR for more than 10-15 minutes your chances of survival are pretty slim.",
"There are certain cases where this doesn’t always... | [
"CPR for 20 minutes? The movies make it look like if the patient hasn't come back in 1 minute, then it's over. Can you explain why someone would need CPR for 20 mins? Rescue breathing for them too? I am very curious about this."
] |
[
"How does buoyancy work in zero gravity?"
] | [
false
] | And can it be used as a means of propulsion in space? | [
"Buoyancy is a force acting on a body as to oppose gravity when that body is immersed in a fluid. This force is proportional to the weight of the volume of fluid displaced. In zero gravity, the fluid has no weight and there is no direction in which buoyancy could act. Buoyancy requires gravity... or more generally ... | [
"I just took the liberty to animate your comment.",
" Yes, you ",
" make a ball float in outer space in a bucket with ",
". Now picture a still bucket (you somehow make the water stay in it).If you push a ball of lead, styrofoam, or any material into the water, it will just push the water away from it. "
] | [
"Here's a good video answering your question. ",
"http://www.youtube.com/watch?v=bgC-ocnTTto",
"In it an astronaut places an alka-seltzer tablet into a spherical water drop. Without gravity the only major force affecting the bubbles is surface tension, which causes most of the bubbles to combine with each other... |
[
"What prevents all dense stars from collapsing into black holes?"
] | [
false
] | I’m just starting to try and learn more about astronomy and physics, and black holes are super interesting to me. From my understanding, it seems that stars with large enough mass collapse under their own gravity when they die out as there isn’t enough energy to keep it stable, and as the mass crunches together from it... | [
"At any given time, a star (or any celestial body, for that matter) is held up by some force opposing gravity. When stars are doing nuclear fusion, the outflow of radiation provides outward pressure which holds the star up against its own gravity.",
"When a star like our sun dies, it collapses down until it reach... | [
"This explains it perfectly, thank you!"
] | [
"Well using the sun as an example, the sun would need to be about 20 times more massive to end its life as a black hole. Stars that are born this size or larger can explode into a supernova at the end of their lifetimes before collapsing back into a black hole, an object with a gravitational pull so strong that not... |
[
"Do trees have a lifespan or are they immortal?"
] | [
false
] | null | [
"They definitely have lifespans. The right conditions can support them for long periods but time gets everything. ",
"Many palm trees have lifespans of about 100 years, which means a lot of the palms that give famous Los Angeles streets their look are almost about to die off."
] | [
"Invididual trees have lifespans, which depends on the species. Some of them, including Great Basin bristlecone pine and Giant sequoia have been verified to live for thousands of years. But that seems to be the upper limit.",
"However, there are clonal trees. These are trees that form clones of themselves from a ... | [
"Some things have pretty good DNA repair mechanisms like the immortal jellyfish. I guess there are a couple of bristlecone pines that have been found to be about 5,000 years old which to me is pretty damn immortal. But I am pretty sure most species of tree will eventually die of old age regardless of conditions"
] |
[
"Does the speed at which a planet (or any other astral object in orbit) rotates affect the strength of its gravitational pull?"
] | [
false
] | I guess what I'm asking is this: The Earth rotates on its axis at a rate of 1 revolution every 24 hours, give or take a few seconds. If that rate changed, meaning it sped up or slowed down, would we feel a change in the strength of the Earth's gravity? If so, does a faster rotation speed mean a stronger pull or a weake... | [
"Kind of, yes.",
"Although, the centrifugal force is not actually real but rather a pseudo force.",
"If you take a bucket on a rope, fill water in it and start swirling it around fast enough in a vertical circle, the water will not fall out, right?",
"Lets take a look at the moment the bucket is upside down, ... | [
"Yes and no. For an observer from space (the moon, let's say) the speed of earth's rotation doesn't affect gravity. If you're standing on the earth, then it does, depending on where you're standing. At the equator, gravity will feel reduced by 0.34% (not much) weaker than at the poles due to the earth spinning.",
... | [
"The gravitational force would not be affected and depends only on the amount and locations of the planet and object's mass. However the net/total force on an object on the surface of the planet would be affected due to an increase in the centrifugal force."
] |
[
"How do parasites change a host creature's thought patterns?"
] | [
false
] | Like the Cordyceps fungus that forces ants and other creatures to climb to the top of a plant stem before the fungus fruits and releases spores. This kind of thing creeps me out but I would love to know how an invader can change the behavior of a much larger host. Cordyceps fungus video, see here: | [
"http://www.medicalnewstoday.com/articles/253802.php",
"http://www.theatlantic.com/magazine/archive/2012/03/how-your-cat-is-making-you-crazy/308873/",
"Toxoplasma is mentioned a lot. Apparently it is capable of altering the disposition of vertebrates, including ourselves. Is there anything to the hype?"
] | [
"Will check those links out tomorrow, it's the night cycle where I am now."
] | [
"Well a parasite like the liver fluke controls a cluster of nerves below the ant's oesophagus, which control various muscles, forcing the ant to climb a blade of grass at night. The exact method by which this occurs is, to my knowledge, still not fully understood."
] |
[
"Does /r/askscience believe travel beyond the solar system is impossible?"
] | [
false
] | [deleted] | [
"I don't believe it's impossible from a physics standpoint, seeing as the Voyager spacecraft is currently on it's way to interstellar space and that thing was built some time in the 70's. So it's clearly not impossible from a materials standpoint. Adding the human element would make the journey extremely difficul... | [
"With current technology, yes it's impossible.",
"But with future technology and a whole lot of patience (multi-generational colony ships, for example), it's not impossible. Just really, really hard."
] | [
"And it's important to remember, that regardless of technological advances, there is zero reason to believe it will ever get \"easy\". "
] |
[
"What is the feeling of \"freefall\"?"
] | [
false
] | I had this question arise the other day on the flight back from Colombia: What is the neurological origin of the gut and body feeling that one experiences with sudden drops (such as during plane turbulence or on a roller coaster)? And one more question: If this is related to a downward acceleration as a physical phenom... | [
"a basic answer ",
"here, in a previous comment",
".",
"to sum up, you have two otolith organs in each ear; they're sensitive to linear acceleration. the utricle senses linear acceleration in the horizontal/transverse plane around the head (left, right, forward, backward); the saccule senses vertical (top to ... | [
"Thanks for the response! That's pretty interesting- I'll remember that in my anatomy class next year"
] | [
"I'll respond to this part of your question: \"What is the neurological origin of the gut and body feeling that one experiences with sudden drops (such as during plane turbulence or on a roller coaster)?\"",
"This feeling is due to the change in the apparent gravity of our situation when engaged in circular movem... |
[
"What makes our bodies stay at 98.6 degrees?"
] | [
false
] | I may be asking a dumb question but, if we are constantly in air conditioned environments, at or around 74 degrees, why are we still at 98.6? I get like warm blood but what inside the body keeps us warm? Is blood just inherently warm or what. | [
"I don't know about the details of how the biological processes work, but I can provide some physics answers. Our bodies are hotter than the environment because they constantly produce heat as a result of our basic metabolic activities. The term \"heat\" here means thermal energy produced that can be moved around, ... | [
"Animals constantly regulate physiological processes. It’s also known as homeostasis, or a tendency towards a state of equilibrium. You can think of homeostasis and body temperature as a thermostat for your body. It can shift depending on conditions (at rest, active, hibernation, infection, etc.).",
"Many of thes... | [
"Others have explained the concept of homeostasis. I'll just explain one part of your question, where you asked how we maintain a body temp of 98.6 when comfortable room temp is 74. I'll be switching everything the Celsius though.",
"Air is a good insulator. Heat doesn't move through it easily, partly because ... |
[
"Freezing Water in a Cup"
] | [
false
] | I have a freezer at home and it's roughly -10 degrees celsius or so (14F), and I had about half a cup full with a block of ice. I added water to the cup of ice and left the block of ice sitting in the cup as I added the water and put it back in the freezer. I came back about 5-10 minutes later and the cup had no ice an... | [
"Water is a much better conductor. Much like how you can get hypothermia in warm water fairly quickly while in the same temperature of air you would fair much better. The water you added was above freezing. This conducted warmer temperatures into the existing ice faster then the air could conduct colder temperatur... | [
"I like your answer, but I think you mean to say heat rather than temperature and that the water transferred heat to the ice faster than the air could transfer heat away from the water.",
"Cold isn't a physical property, only a description of relatively less heat than something else and it can't be conducted to a... | [
"here are the two things that are going on:",
"1) when you added the water the mixture of ice and water was already working on becoming a consistent temperature. meaning after a while the entire mixture of water and ice would be the same temperature. the only way it would be ice is if after the temperature is t... |
[
"Where does carbon 14 come from?"
] | [
false
] | [deleted] | [
"It's mostly created on Earth in the upper atmosphere due to bombardment of cosmic rays and nitrogen.",
"This is why it's such a good dating tool, stuff sealed from the atmosphere won't get exposed to any more and the amount of nitrogen and the cosmic bombardment rate is roughly fixed and insensitive to anything ... | [
"Thank you, this is exactly what I was looking for! Have a nice day! "
] | [
"Have some gold"
] |
[
"Would water work as a Faraday Cage?"
] | [
false
] | Imagine if a big solar flare happened on the Sun. I have a mobile device which would get damaged by that and I want to save it. If I put my mobile device into waterproof box and then I put it under water. Would that water make a Faraday cage effect, which would save my mobile device from the solar wind actually damagin... | [
"They are the same microwaves, frequency and wavelength. Just their pattern of re-radiation changes. The array of hole in the microwave oven window become a ",
"phased array antenna",
"."
] | [
"First you have to understand a lot of what people call Faraday Cages are really a shielded enclosure. The original concept of the ",
"Faraday Cage",
" was for static electrical charges and not radio frequency signals. But the concept has morphed into that all shield enclosures are called Faraday Cages. ",
"... | [
"As for holes in the enclosure, many people think that a hole smaller than a wavelength of the signal will block it. ",
"Wait, what does this tell me about microwave ovens? Isn't the mesh supposed to absorb all the microwave radiation?"
] |
[
"Are gas giant planets perfectly round?"
] | [
false
] | At some given radius, does Jupiter have the same density all the way around or does the density of gas vary throughout? If not, what causes the density variance? | [
"Jupiter, like all other planets, is not perfectly spherical, but instead is ellipsoid in shape, with a bulge around the equator. This is caused by the rotation of the planet around its axis pushing matter more outwards the closer to the equator it is.",
"If you measure the radius at the pole you'll find a figure... | [
"The famous \"great red spot\" on Jupiter is actually a very large storm in Jupiters atmosphere.",
"Well, sort of. It's certainly a vortex, but calling it a \"storm\" isn't quite right.",
"Storms on Earth are generally regions of low pressure. Curiously, though, the Great Red Spot (GRS) is actually a region of ... | [
"That's very interesting, thank you!"
] |
[
"What's particular about humans that we evolved advanced intelligence?"
] | [
false
] | null | [
"Anthropologists have chalked this up to the fact that our ancestors began cooking our food. This increased the amount of neurons in our brain to approximately 100 billion. (I've heard comparisons that animals around our size have 30 billion.)",
"So what does cooking food have to do with brains? When people eat... | [
"Humans are A: Diurnal (active during the day), B: have opposable thumbs, C: have vocal apparatuses capable of making precise sounds.",
"Most meat eaters hunt during the night, but early primates hunted during the day. Now, the African sun is very hot, hot enough to make brain cells die much faster. So over time,... | [
"So you're saying that the factor prohibiting other species from evolving greater intelligence is the energy cost? I don't really understand how the concept of marginal increases in intelligence would work, but for larger animals that already have huge caloric requirements, it seems the requirements of increased br... |
[
"If we have a compressed spring and bring it to space, then release it. In what form does the energy leave?"
] | [
false
] | It can only be heat as far as I know. On earth it would be sound and kinetic too, but what about deep space? It can't all be heat? | [
"If there isn't any friction within the spring the energy will stay, shifting back and forth between kinetic energy and potential energy as the spring keeps oscillating until something stops it. With friction mechanical energy will dissipate to internal heat in the spring. The heat causes the spring to emit energy ... | [
"Thanks a lot for that answer! Makes some sense. :). So the spring will actually keep going \"up and down\" in space, or will it be vibrating? I'm just trying to visualize the oscillating. And this will slowly go over into radiation, and thus losing the spring energy?",
"If i got that right now, I would be happy.... | [
"The center of the spring will stay in place while the ends expand and contract in unison."
] |
[
"Question about photons, emission, absorption and time:"
] | [
false
] | I've been trying to follow some of the questions asked here recently and I apologize if I've missed some crucial tidbit that would make this all make sense to me without asking, but: If a photon's proper lifespan is zero, and it is emitted at the exact same instant it is absorbed, how can it be correct to say that empt... | [
"\"Proper lifespan\" isn't what we want to say here. If we're going to talk about this, we want to do so in a rigorous and disciplined way, in order to maximize clarity of thought.",
"What we want to talk about here is ",
" The elapsed proper time along a trajectory is the integral over the curve parameter of t... | [
"quite well, thank you ;-)"
] | [
"it is emitted at the exact same instant it is absorbed",
"Actually there's some delay, though I don't know the time scale here. But IIRC, it's why light propagates more slowly through materials.",
"can it be correct to say that empty space contains photons?",
"Because to all non-light speed observers, light ... |
[
"Why do we see meteor showers at roughly the same times each year?"
] | [
false
] | If the debris field is orbiting the sun too, why does the earth move through them with such regularity? | [
"Debris fields orbit the Sun on highly elliptical orbits because they are generated by comets, which also have highly elliptical orbits. There is debris strewn all along the elliptical path, so whenever we cross said path, we run into some of that debris.",
"This image",
" shows the debris field as the diagonal... | [
"On scales as large as the Solar System, if a comet's orbit is inclined by even a degree with respect to the ecliptic (the plane that all the planets approximately orbit in), it will be significantly out of the plane. So it's not too surprising that the comets' orbits don't coincide with Earth's at more than one p... | [
"Do Earth's and the comet's orbits coincide at only one place? I guess I'd expect two or four. Are the elliptical orbits in the same plane as Earth's?"
] |
[
"What is a Lie group?"
] | [
false
] | What is its application? What field of math is it a part of? Why is it so complicated? And finally, what textbooks do I have to read to get to that level, I figure Linear Algebra is step 1? I only ask here because hours and hours on Wikipedia got me nowhere. | [
"You can get a basic idea of what a Lie group is fairly easily. It's just a set along with a binary operation, such that the operation obeys the group axioms (closure, associativity, and the existence of an identity and inverse), and the set describes a... well, smooth thingy is the best nonformal way to put it. A ... | [
"What field of math is it a part of?",
"Its used a lot in mathematical physics. For example the angular momentum operators belong to SU(2). Its also used in studying fiber bundles.",
"It would help quite a bit in knowing what exactly your background is, are you a senior level physics student who has heard the t... | [
"A Lie group is a group and a (smooth?) manifold, such that the group operations are smooth/continuous. This makes it part of algebra (because of the groups) and differential geometry (because of the manifolds), although to be frank, I guess the majority of applications are found in the geometry field.",
"I don't... |
[
"Why is Hydromorphone not called Hydromorphine. Same for hydrocodone why is it not called hydrocodeine? Or are they just not related?"
] | [
false
] | null | [
"Morphine and codeine have allyl alcohols in their structures which are converted into ketones to make hydromorphone and hydrocodone respectively. Compounds with ketones in their structure typically end with the suffix -one. ",
"See the top half of this image. "
] | [
"So its an organic chemistry nomenclature deal. When the -O bond become a ketone (=O) the ending changes to -one.",
"",
"https://pubchem.ncbi.nlm.nih.gov/compound/Morphine#section=2D-Structure",
"https://pubchem.ncbi.nlm.nih.gov/compound/Hydromorphone#section=2D-Structure",
"http://www.chem.uiuc.edu/GenChe... | [
"Hydromorphone differs from morphine in that an alcohol group is replaced with a ketone group. Ketones are assigned names ending in “-one”.",
"If you compare the diagrams at ",
"https://en.wikipedia.org/wiki/Morphine",
" and ",
"https://en.wikipedia.org/wiki/Hydromorphone",
", the ketone group in the latt... |
[
"An accurate Helium thought experiment?"
] | [
false
] | [deleted] | [
"An \"ideal\" gas is one which doesn't really interact with other particles accept during collisions. So imagine a bunch of tiny little bouncy balls flying around in a vacuum so no wind resistance. Next you must remember that the bouncy balls on average don't lose any energy during collisions. So you've no got a ro... | [
"\"",
"\"",
"This is not correct. Helium is a gas, and will fill the container pretty much uniformly.",
"Also, a helium balloon floats in our atmosphere for exactly the same reason that a boat floats in water - they each weigh less per unit of volume than the fluid (water or atmosphere) that they are in. Th... | [
"Helium is a gas, and will fill the container pretty much uniformly.",
"This is mostly true, unless the container is very, very tall. ",
"As the column grows in size, atoms at the bottom of the container will compress from the weight of all the atoms above it. It's the same reason that atmospheric pressure decr... |
[
"What are the benefits and risks of \"inhaling alcohol?\""
] | [
false
] | Machines that vaporize alcohol and mix it with oxygen apparently exist as an alternative method of consuming alcohol. What are the benefits/dangers of this? Inspired by a current AskScience about bathing in alcohol: | [
"When you ingest alcohol, it's taken up into your bloodstream and the first places it goes is through the ",
"Portal Venous System",
" to the liver. It gets metabolized there in what's called the ",
"First Pass Metabolism",
" before it goes anywhere else in your body.",
"Basically, anything that you're e... | [
"Its also important to note that you lose the ability to vomit as well, which increases the risks of alcohol poisoning. "
] | [
"so how come when I take a shot of something really stiff I can feel drunk within seconds? is it just a placebo affect, some sort of muscle memory of being drunk other times?"
] |
[
"What are the downsides to a Molten Salt Thorium Reactor?"
] | [
false
] | Seems like its sort of an energy dream other than obtaining funding. Whats the fine print? | [
"not an expert but...",
"\"Molten salts can be highly corrosive, more so as temperatures rise. For the primary cooling loop of the MSR, a material is needed that can withstand corrosion at high temperatures and intense radiation. Experiments show that Hastelloy-N and similar alloys are quite suited to the tasks a... | [
"First of all, I suggest everyone read this:\n",
"http://energyfromthorium.com/pdf/MSadventure.pdf",
"Secondly, since this post gets referenced a lot:",
"Four problems with the MSR for those unaware",
"-Uses ultra expensive Hastelloy-N Alloy to house the salts. Its not even made anymore, but can be made."... | [
"It's an experimental design that has never been made as a full scale power generating plant.",
"No one has any idea whether it can be done economically and safely. It is an interesting concept that has never been proven to work well. It isn't as big a leap as fusion, but it's not much further along in developmen... |
[
"I just learned how cosmic rays are primarily (positively charged) protons and atomic nuclei. How is their charge balanced?"
] | [
false
] | If earth just sucked up positive particles it would accumulate a charge, so there must be some incoming negative charge to balance it? Are these just electrons, or other particles as well? | [
"We think ",
"cosmic rays are generated in supernovas",
" by shock waves. My understanding is that there are similar amounts of positive and negative particles generated initially, with similar velocities. But the electrons are screened out by ",
"inverse compton scattering",
". Basically, the electrons can... | [
"It seems like you are assuming the net flux of cosmic rays to the earth is neutral, but in reality it is ",
"99% positive nuclei and 1% electrons",
". Also, they are generated by ",
"supernova shock waves",
", not from nuclear fusion per se."
] | [
"You really need to read more about cosmic rays before you answer questions about them here. The wikipedia page would be a good place to start. The 1% vs 99% refers to the abundance of positive vs. negative particles. The proton-electron mass ratio is close to 2000, so if electrons were 1% of the mass of cosmic ray... |
[
"How can a system at an equilibrium have maximum entropy?"
] | [
false
] | I’m trying to understand the concept of entropy but I don’t understand why, if entropy is how chaotic a system is, a system at an equilibrium is considered to be at maximum entropy? Isn’t such a system at its most inactive state? I’m sorry for my use of simple words. Edit: I’m amazed by the quality of the replies I got... | [
"I don’t understand why, if entropy is how chaotic a system is, ...",
"Ah ... this is the block in your understanding here: although historically entropy was ",
" as a measure of \"disorder\" in a system, and although it is still often ",
" as such, the truth of the matter is that entropy has virtually nothi... | [
"if entropy is how chaotic a system is,",
"Entropy and chaos are unrelated concepts. Entropy is a mathematically well-defined quantity that can be calculated from the probability distribution of microscopic states of a statistical system. It's a concept that is useful not only in physics, but more generally in st... | [
"An alternative but equivalent definition of entropy is ",
"Boltzmann's entropy",
", where Ω is the number of microstates of a given macrostate.",
"In the 100 coin flip example, the macrostate is \"50 heads, 50 tails\", or \"100 heads, 0 tails\". The microstates are all possible sequences of 100 flips. ",
"... |
[
"How can yogurts like Activia have \"active cultures\" but show no evidence of gas being produced in the container (the lids are not popped up, for example)?"
] | [
false
] | null | [
"Yogurt is made over a heat source at about 115 F and becomes too acidic for most bacteria to live due to fermentation products. It is then cooled down so the heat-loving bacteria that survived become mostly inactive. They're not dead but they're also not doing much.",
"Activia markets the presence of bacteria mo... | [
"If there is any evidence of the benefits of \"Bifidus Regularis\"...",
"\"Bifidus Regularis\" is a scientific sounding name for ",
", an anaerobic Gram-positive rod that is found as a commensal bacterium in the mammalian intestinal tract. Of course, this is just one bacterium used as a probiotic and other comm... | [
"Theyve been sued and had to pay money because of those false health benefit claims."
] |
[
"Were superconductors theorised first or discovered?"
] | [
false
] | The title say it all really. Were they mathematically predicted first or just discovered by accident or similar? | [
"In the early 1900s, there were competing theories about what would happen if a sufficiently pure metal were lowered towards absolute zero. Some thought that the trend of lower resistance would continue all the way down, others that electrons would become immobile and resistance would increase towards absolute zero... | [
"I expect people didn't believe him at first? The idea of exactly zero resistance sounds completely contrary to how most of physics works in the real world, so did other scientists doubt his measurement? Or was the testing mechanism sufficiently accurate or constructed in a way that removed all doubt?"
] | [
"I am having trouble finding sources that answer your question, but he was awarded the Nobel prize in physics only two years later, mostly for his work on liquefying helium (which allowed him to do these experiments in the first place). "
] |
[
"Did the 1918 pandemic have asymptomatic carriers as the covid 19 pandemic does?"
] | [
false
] | null | [
"As far as we can tell, most if not all viruses have the potential for asymptomatic carriers. Do we know for sure that the 1918 Spanish Flu did? Not with direct evidence. That kind of testing just didn't exist back then. But we can say with a fairly high degree of confidence that yes it did."
] | [
"Yes it did, the numbers will never be known though since the government had no testing capabilities like we have today.\nAsymptomatic infections happen because of the slight differences in the immune system from person to person that are caused by genetic variation.\nSome people are just bound to have a immune sy... | [
"Does anyone have a citation that supports the idea that the mutations of Spanish Flu that we see every year have asymptomatic and pre-symptomatic carriers? My anecdotal experience suggests that may be the case."
] |
[
"Is it possible to create an electric jet engine?"
] | [
false
] | Jet planes make use of axial-flow compressors to compress air. They then mix the compressed air with fuel and burn both, resulting in gases escaping at large velocities through a nozzle. Is it possible to do away with the burning fuel part, and just compress the air and let it flow out through a nozzle? I understand th... | [
"A modern ",
"jet engine",
" is actually a compressor and turbine in one machine. The turbine harvests some of the energy from the burning fuel and uses it to power the compressor. The rest of the energy provides thrust or is lost as heat. If there is no energy input (fuel) then the turbine won't be able to ... | [
"In a normal jet engine, the \"burning fuel\" part is what makes the back-end spin,,,, which is what turns the front part. If you eliminate the fuel-burning part, then you don't need the back end either, so all you have is a set of propellers on an electric motor. Which will certainly work (ducted fan) but isn't re... | [
"What prevents the pressurized air from escaping out the front?"
] |
[
"Diet Drinks, Dentistry Dissension"
] | [
false
] | Diet soda does contains sugars. They are simply sugars that the body cannot digest, so they pass through without calorie gain. Question One: can the bacteria that cause cavities feed on diet sugars? Restated, are there compounds in diet soda that can cause dental issues? I do have another diet soda related question, wh... | [
"The carbonic acid in diet soft drinks ",
" gradually dissolves the material that teeth are made of."
] | [
"In addition to apartame (Nutrasweet) and sucralose (Splenda), some diet formulations contain ",
"ACE-K",
", a sweetner and sweet enhancer or sugar alcohols such as ",
"sorbitol",
". None of these have been conclusively shown to cause tooth decay, although there is some speculation that sugar alcohols can ... | [
"Nutrisweet, which is in Diet Coke, isn't an inactive sugar, it's amino acids, which both you and bacteria can digest, but the amount is too small to have a significant caloric content for the beverage.",
"It's 100% bullshit that diet sodas have any association with weight gain or cancer.",
"There's another kin... |
[
"Why is the strength of my fingers so weak during the few minutes after waking up in the morning?"
] | [
false
] | null | [
"dentist here, most of my understanding of physiology pertains to the head and neck, but i have some understanding of extremities as well.",
"the further away you get from your heart (ie your fingers and toes) blood circulation relies less on your blood pressure and more on your muscles compressing and moving the... | [
"Thanks for the reply! This certainly makes sense. "
] | [
"Thanks for the concern, but it's definitely not a medical issue. It doesn't happen every morning (presumably it's more likely after a night of deep, non-restless sleep now that I've read the comments). The few people I've asked about this before ",
"r/askscience",
" all said they knew exactly what I was asking... |
[
"I want to have a career in Astrophysics in the future; I'm 14 years old now. What can I do to better prepare myself?"
] | [
false
] | null | [
"I'm not im college yet but I plan on double majoring in particle physics and astronomy. I think astrophysics is similar. I've read lots of books, watched lots of shows on the Science Channel, and just stuff like that. Lots of websites can give you more information, I can give you some if you'd like. I can assure y... | [
"Thanks a lot for the reply! You were right, I have read multiple books on the subject but I still hunger for more. It would be fantastic if you could recommend any to me you found entertaining or informative."
] | [
"I haven't read any books labeled \"astrophysics\" as the subject. But what I have read different ones about physics and astronomy; could you tell me which ones you prefer?"
] |
[
"Do other planets experience earthquakes?"
] | [
false
] | null | [
"They do.",
"The Apollo missions carried ",
"seismometers",
" that were deployed on the surface and measured ",
"moonquakes",
".",
"Currently, a mission called ",
"InSight",
" has deployed a seismometer on Mars to record the phenomenon and better understand the planet's interior."
] | [
"Any process that can fracture rock or generate differential stress across a preexisting fracture is capable of generating a quake. A variety of different processes have been proposed for different populations of moonquakes, including ",
"meteorite impacts",
", ",
"tidal stresses",
", and ",
"expansion an... | [
"It was my understanding that a celestial body had to be geologically active to experience quakes? \nWhat are the causes of Moonquakes and Marsquakes?"
] |
[
"When astronomers refer to distances between galaxies, do they mean the distance as we observe them or as they are now?"
] | [
false
] | For example, if astronomers describe the distance between two galaxies in a supervoid that is a billion light-years away to be 150 million light-years. Is that distance representative of what we have observed (essentially an image from a billion years ago) or as it is now (accounting for the expansion of the universe)? | [
"It'd be distance at the observed time in the past. We sometimes use \"comoving units\" which do take into account the expansion of the universe. If two objects are a kiloparsec apart back when the universe was half its current size, then they are \"two comoving kiloparsecs apart\".",
"But additionally, galaxies ... | [
"Yes, they meant the distance from ",
" point to ",
" point."
] | [
"Are there efforts made to create a map of what the universe probably looks like ",
"?",
"I'm not sure if that word \"now\" has a clear definition."
] |
[
"If the heart is a muscle, after running, will eating protein repair it and make it stronger like other muscles?"
] | [
false
] | null | [
"You mean like ",
"hypertrophic cardiomyopathy",
"? Actually, the article says \"Athletes are known to have enlarged hearts. It is the body’s way of adapting to intense exercise, and it is not a disease like hypertrophic cardiomyopathy.\""
] | [
"Well, it wasn't necessarily a question about athletes, but the best way to improve cardiovascular performance for a layman who runs. So I know that after I work out, I should eat protein to help get stronger, and I was wondering if the same advice pertains to my heart after a cardio workout.",
"The article, it ... | [
"Fun fact, Sectarian the horse (won a bunch of races and) was found to have this condition (this was found after his death)"
] |
[
"Due to Climate Change, How Long Before Some Places Are Uninhabitable Due to Temperature?"
] | [
false
] | More specifically, high temperatures - I know that some places have recorded individual temperatures over 120, but I'm talking about over a prolonged period of time. Any ideas on how soon/where? | [
"There's no specific temperature at which a place becomes uninhabitable. Death Valley already exists--but it's a tourist attraction."
] | [
"It's not so much straight temperature that's important, it's wet bulb temperature. This is temperature taking into account evaporative cooling- important because humans sweat and can survive higher temperatures through evaporative cooling. A human can survive very high temperatures in dry air, but a wet-bulb tem... | [
"Anywhere where humans currently reside, they could easily adapt to an increase of 1-5 degrees K/C. The problem is more about self sustaining, when local crops or ecosystems crumble, if they do. Any question regarding raise in temperature works on almost a global scale, what happens when we lose 5 % of our agricult... |
[
"[Chemistry/Physics] What is an effective way of separating carbon isotopes on a small scale in a lab?"
] | [
false
] | [deleted] | [
"Are you looking to get pure ",
" ",
"C? That'll be a challenge. You can buy highly enriched ",
"C containing compounds, but reducing them all the way down to pure elemental carbon on the lab scale will not be easy."
] | [
"Extracting pure carbon from molecules with C13 only is way easier than doing isotope separation on your own.",
"@",
"u/grandmasteroftea",
":",
"on a small scale in a lab?",
"Forget it."
] | [
"If you think about it, the easiest way to get ",
"C is some kind of distillation of a molecule containing a single carbon atom. Your choices are CO, CO2, methanol, formaldehyde, formic acid, maybe formamide or urea.",
"If I had to guess, I would imagine that the infrastructure already in place to generate pure... |
[
"Can ice be compressed into water?"
] | [
false
] | I have wondered about this for some time. Since ice is not as dense as water and it forms a crystal structure, I was wondering if you applied enough pressure, could you break the structure and turn the ice back into water? | [
"Yes it can! The phase of water, whether solid, liquid, or gas, is a function of both temperature and pressure. ",
"Here",
" is the phase diagram for water. It will show that above ~100kbar (100,000 times normal atmospheric pressure), water will be solid, as in ice, no matter what temperature. ",
"EDIT: Oops,... | [
"Pressure, along with friction, is also part of the reason why ice skates work the way they do (or so we think). The blade has a very small surface area and a person is relatively heavy. Since pressure = force/area you can see the pressure exerted by the ice skate blades is very large. The pressure slightly compres... | [
"I suspect that the reason that snow melts when you pack it is that heat from your hand transfers to the snow. Unless the snow is sitting right at 0 C, you would have to impart an incredible pressure to compress it into water. This is clearly not what happens because even a well packed snowball contains a lot of ai... |
[
"How loud is your pulse in decibels?"
] | [
false
] | If you you could link to an article or something, that'd be great. Also, some bonus questions that I have: How loud is your breathing? and How is our hearing absolute threshold measured? | [
"From what point? From inside your skull where if it's quiet enough you can hear your own blood flow and vibrations travel through your bones? Or from immediately next to the heart, in open air? Same goes for breathing. You hear it, but it would be extremely difficult to measure the vibrations going through your bo... | [
"I'm an acoustical engineer, and I have studied psychoacoustics. So I can comment on some of this.",
"It's definitely possible to measure the vibration of a pulse, this is how stethoscopes work. The only difference here is we would be converting it to an electrical signal. The problem would be getting it into a m... | [
"This is not an answer as to what the lower limit of audibility is, but I do have the answer to the ",
"range of human hearing",
"."
] |
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