title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Does placebo effect occur when there is no physical placebo (eg. pill)?"
] | [
false
] | For example, if a cancer sufferer prayed everyday instead of getting chemo? PLEASE NO SPECULATION I'M JUST USING PRAYER AS AN EXAMPLE!!!!!! | [
"Of course that can be a placebo. Anything that you think is having some sort of impact can act as one."
] | [
"I believe your interpretation of effect from placebos is incorrect. While it is likely true that there isn't a direct physiological action from the placebo itself (say the sugar in the pill); there is a multitude of support showing physiological effects from the belief in the treatment. Neurological changes, as de... | [
"Just to clarify, what mightberight means by \"patently false\" is \"is not consistent with experimental evidence\". It's not a logical falsehood, but an empirical one."
] |
[
"Why can't we utilize the crushing forces of ocean depths to generate green energy?"
] | [
false
] | null | [
"Ignorance is not stupidity.",
"\nIgnorance is not knowing.",
"\nStupidity is not knowing and never asking."
] | [
"this isn't actually something that can work ",
"This one, there's no mechanism to harness energy from that. You can't run a turbine off water that isn't moving, you can't harness the pressure deep under the ocean any more than we could harness the weight of a brick to generate electricity. Now if you have a str... | [
"I appreciate how you cropped out the part about my being stupid. Upvote for sparing my feelings."
] |
[
"Why is the Number Needed to Invite (NNI) so frequently reported and considered in clinical studies?"
] | [
false
] | How is it reconciled with the Number Needed to Screen/Treat when trying to look at the quality of a screening test or treatment? | [
"Intention-to-treat, rather than strict randomized control trials, are often used in assessing screening efficacy for various reasons. I'd hope outcomes other than NNI would be reported for treatment efficacy, but I suppose it could be done. ",
"Here's a decent review of the subject."
] | [
"Thanks! That review was really helpful. I guess if you have the NNI and the NNS then you essentially get bounds for your test with the former more conservative and lateral more liberal. "
] | [
"Agreed. NNI is conflated with many other factors, such as prioritizing that particular treatment, ability to attend scheduled appointments, interest in participation in a trial rather than standard clinical care, etc. It can still provide important information, but as you point out, it should be considered in cont... |
[
"Why do only some wounds cause scars when healed? And why do scars appear different from the rest of the skin?"
] | [
false
] | null | [
"generally scar tissue is produced by the body as a last resort, because it isnt as good as replacing the skin. Scar tissue is different from the skin because it is not made up of the same materials. If the wound is big enough that the body cannot heal the wound with its normal repair mechanisms it resorts to scar ... | [
"I would add in that scar tissue also forms from other types of damage i.e. binge drinking will cause liver damage and scar tissue there as well, scar tissue is not limited to just skin.",
"Also for OP appearance of scar tissue is different from normal tissue because it is not normal tissue, less porous, less str... | [
"Generally speaking, in the case of skin, the different appearance of the scar tissue is for the most part due to an overexpression of collagen fibers along with other matrix proteins. Wound healing is a complex process and the skin will heal itself completely if possible, however in the cases where it is not, inst... |
[
"Are there ocean deserts? Are there parts of the ocean that never or rarely receive rain?"
] | [
false
] | null | [
"I appreciate the clear explanation made easy to understand, slut_4_cum. So could you say gyres and ocean deserts are interchangeable terms?"
] | [
"I appreciate the clear explanation made easy to understand, slut_4_cum. So could you say gyres and ocean deserts are interchangeable terms?"
] | [
"Yes. If you look at a map of annual precipitation, a few of the recognisable land deserts look like they stretch well out to sea. Mainly off the western edge of continents, eg. off Western and Southern Africa (Sahara and Namib deserts)."
] |
[
"So, sperm live about 5 days, and an unfertilized egg lives about 1 day. But if the egg gets fertilized it lives on its own another 3-4 days before it implants. Why/how does a fertilized egg live longer than an unfertilized one?"
] | [
false
] | I'm using for my numbers. I would think after fertilization it would be busy doing more stuff and burning more resources. Unless maybe it was super tiring for it to crank out the chemical signals to attract the sperm? Does the fertilized egg get to use some of the extra energy stores the sperm was carrying with it? Edit: maybe more to the point, why doesn't the unfertilized egg live longer? If it's got enough mojo to keep rollin' that many more days after it's been fertilized, why not stay alive longer and increase the window in which it could get fertilized? I hear you guys saying the unfertilized egg has a cell death programmed, but why would it program a death so soon? Unless for some reason while it's unfertilized it's busy doing stuff that damages itself such that it wouldn't produce viable offspring if it were fertilized? | [
"Ok, so you're driving in your car, with your girlfriend trying to decide if you want to go to the next town over to see a band. It takes a half tank of gas to get there and back, so if she says yes before a half tank, it's all a good time. If not your just yell that you didn't want to go anyways go home and sleep ... | [
"Once the sperm fertilizes the egg chemical signaling begins to happen and the egg goes into a sort of \"survival mode\" where the molecular machinery to survive and begin dividing is turned on and the molecular machinery for programmed cell death is turned off. "
] | [
"At some point, the egg doesn't have enough energy to start dividing. One you reach that point, staying alive waiting to be fertilized is pointless."
] |
[
"Are there any actual scientific theories regarding the creation of the universe?"
] | [
false
] | null | [
"The Big Bang",
" is the most widely-accepted, though it's pretty widely known.",
"Some steady-state hypotheses have been put forth as well",
", though they have considerably less support these days, given the preponderance of evidence for the Big Bang."
] | [
"Ah, so you're looking for more of a \"what caused the big bang\" sort of thing? That's a bit harder, as physics gets pretty weird back at the beginning of the big bang, and so asking what came before is even more challenging. In fact, if time is a dimension of the universe itself, asking what came before the big b... | [
"Ah, so you're looking for more of a \"what caused the big bang\" sort of thing? That's a bit harder, as physics gets pretty weird back at the beginning of the big bang, and so asking what came before is even more challenging. In fact, if time is a dimension of the universe itself, asking what came before the big b... |
[
"Can babies really pick their parents out?"
] | [
false
] | My wife and I had a baby girl and she spent some the time in the NICU and the nurses said talking to her in her isolet(sp?) Would help her. Can babies really pick their parents voice out that early? And they said our daughter could smell my wife and gave us a little blankie to get my wife's scent on. Can babies really do that too? | [
"They've been hearing her voice in-utero for a while, so yes, she's able to recognize her mother's smell and voice because he's lived with it for months already. If you talked to the bump she knows your voice too!"
] | [
"Yes, especially the mother. The moment the ear to brain connection starts functioning it can hear the mother's voice. Anyone else too if they're loud enough and spend enough time around the mother. Outside of the heartbeat and breathing, the voice is the most common sound in it's little world, and once they're out... | [
"How do we know they can still recognize from outside the womb? It's got to sound very different coming through the air instead of through the mother's body."
] |
[
"If phone lines (but not necessarily modems) transmitted perfectly, how fast could dial-up modems transfer data?"
] | [
false
] | Since the transfer rate of the modem depends on how fast it can modulate (and demodulate) bits into an interrupted tone, phone line noise would cause high speed modems to lose data in transmission, but if a phone line were to be perfect (i.e no noise and all transmissions came through the other end of the line exactly as they were input), how fast could we potentially build a modem? | [
"Infinite. The easy explanation is simply a proof. If I have no noise, for any message, such as 01010100001, I can find a voltage level between 0 and 1 whose greedy binary expansion is that message. I can then send that value, and on the other end (since no noise) read that value and determine my message. No noise ... | [
"To make it simple there are two factors: noise and channel. Any channel is limited in capacity and always makes a distortion to a signal. Most like it introduces an echo which affects a receiver side and can't be evaded from a signal completely, as information was already lost. Another problem is a noise and again... | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"/r/estimation",
"/r/theydidthemath",
"If you disagree with this decision, please send a message to the moderators."
] |
[
"Mercury is an ingredient in some skin whiteners. How toxic is exposure to 30 000 ppm of Mercury?"
] | [
false
] | null | [
"Here",
" is an MSDS I found. This will give you government regulations on skin and vapor exposure. I would assume that 30,000 ppm mercury is extremely dangerous based on the IDLH number. IDLH stands for \"Immediately Dangerous to Life and Health\" and represents the maximum suggested exposure for a \"one-time... | [
"I assume there are different values because ones I'm aware of are for presence in marine sediments. In water, animals will be ingesting it, but in this case people are rubbing in on their face.",
"But NOAA guidelines show an ERM (effects range median) of 0.71 ppm, and ERL (effects range low) of 0.15 ppm. Those a... | [
"I almost forgot. Keep in mind that my link is for pure, liquid mercury. Mercury inside of a cream will have different properties. Now, I'm only speaking for the United States, but every manufacturer of chemicals (whether pure or mixture) must put out an MSDS for the public concerning each product's health hazar... |
[
"Is it possible for humans to learn new reflex actions?"
] | [
false
] | For a example if a boxer dodges enough punches, could they eventually train their nervous system to skip the brain completely and just dodge involuntary without thinking about it? So something like a learned extension to the . I know training makes people better and faster at responding to stimuli but I'm specifically asking about developing new reflex arcs (or at least I hope I am, I just now googled all these terms). | [
"On short, no. The action of dodging a punch would require input that suggests a punch is coming and where it is going to land (left vs right), which will most likely be visual (or possibly auditory stimuli if someone threatens you, but it would be difficult to dodge based only on sound), so the action will always... | [
"As has been pointed out here, a reflex doesn’t involve the brain. Stimulus sends a signal to the spinal cord which sends back a signal for the proper response. No thinking needed, it is very fast. In order for a boxer to dodge a punch, he has to know the punch is coming. That information comes from the eyes and mu... | [
"A morbid thought: If someone's head were chopped off, a reflex mediated in the spine would suggest the reflex would still trigger? So a headless body would react to their hand being placed on a hot surface?"
] |
[
"Is there any credible research that cell phone 'shields' aka ‘EMF protection devices’ are effective?"
] | [
false
] | [deleted] | [
"They should still buy one of my tiger repellent amulets just to be on the safe side."
] | [
"Okay, but protection from what? What's the mechanism by which harm comes? These are the specific details that get overlooked, and the basis by which these products make money. To prevent something from happening you need to disrupt the mechanism by which it happens. The only way to properly disrupt electromagnetic... | [
"Okay, but protection from what? What's the mechanism by which harm comes? These are the specific details that get overlooked, and the basis by which these products make money. To prevent something from happening you need to disrupt the mechanism by which it happens. The only way to properly disrupt electromagnetic... |
[
"What is it that prevents scientists from developing an HIV vaccine?"
] | [
false
] | null | [
"Because HIV is an exceedingly difficult virus to vaccinate against; covid is an exceptionally easy one.",
"The strategy proving so successful with covid vaccines (generate antibodies to the envelope's proteins) was tried ",
" with HIV (for covid, the envelope protein is spike; for HIV, it's gp120/gp41). It f... | [
"The problem with HIV: it has literally ",
" to evade the adaptive immune system. HIV reproduces by injecting its genetic information into the nuclear genome of the cell. But HIV is an RNA virus whereas the genome is written in DNA. So it comes with the reverse transcriptase - a molecular machine that transcribes... | [
"I would hope that the latter half of what I wrote made it clear to anyone remotely familiar with central dogma. It’s the latter."
] |
[
"Once a black hole decays from Hawking radiation what is left behind?"
] | [
false
] | Once the hole is completely decayed what happens to everything that was "sucked up". Is it just a mishmash of everything from light to stars and planets? Or once it decays does it re collapse into a new black hole or a star? I'm so confused on what happens to black holes that die. | [
"Hawking radiation is insignificant for massive black holes. It only becomes very important when a black hole is very small and has little mass or energy left, and it causes the black hole to lose mass and energy very quickly. We're not really very sure what is released in the last few milliseconds of the black ho... | [
"Nothing but the radiation that was emitted, which is probably far away from the black hole by then."
] | [
"Or once it decays does it re collapse into a new black hole or a star?",
"By the time it gets really small it is most likely billions of years after it initially formed and it has been radiating away energy over those billions of years, so it isn't in any danger of just re-collapsing. ",
"I'm so confused on wh... |
[
"Why are 10 dimensions needed in string- theory ?"
] | [
false
] | please explain why "superstring" needs 10, M-Theory 11 and bosonic even 26 dimensions, equations and everything else is very much appreciated. | [
"Basically, and someone can correct me if I misrepresent things, there's a mathematical procedure you do in quantum field theory called renormalization, which takes equations that would normally give an infinite answer and makes them finite. You can do this with a variable D in your equation that represents an arbi... | [
"This is exactly what I was looking for. Thanks.",
"And I'm not OP. "
] | [
"Very few, if any, will be able to explain it very concisely.",
"If you're really interested, I'd recommend a book \"The Elegant Universe\" as a starting point. ",
"Edit: and it looks like iorgfeflkd is one of those. I'd still recommend the book"
] |
[
"How cold, and for how long, does the earth have to be in order for all bodies of water to completely freeze solid?"
] | [
false
] | null | [
"You wouldn't necessarily have to be that cold. The phase diagram of water (",
"http://ergodic.ugr.es/termo/lecciones/water1.html",
") shows that even at the bottom of the Marianas Trench (pressure of ~100 MPa), water will still freeze at ~0ºC. Granted, the oceans aren't pure water, so the freezing point drop... | [
"Assuming that the coldness was coming from some direct source, you would have to have a very cold temperature. The first to freeze would be lakes, ponds, etc. The oceans would be very difficult to freeze, because of enormous size and freezing point depression due to dissolved salt in the oceans. One of Jupiter's m... | [
"When you say 'water' do you actually mean water, or just a liquid of similar properties? "
] |
[
"If stars convert mass directly into energy via fusion, is there a \"natural\" way to convert energy back into mass?"
] | [
false
] | I just saw video explaining how stars convert mass into energy. Is there a way that does the opposite? And if not, will there come a time in the universe where all mass will be eventually pure energy running around forever? | [
"where all mass will be eventually pure energy running around forever? ",
"Technically there are no such things as \"pure\" energy nor mass. Mass and energy are properties, ability to resist acceleration (inertia) and ability to do work respectively. They are also conserved quantities which means that they can't ... | [
"This is wrong.",
"Nope. It just is something that isn't taught as often in chemistry because the effect is so small. ",
"If you add up the masses of 6 protons and 6 neutrons, you will find that the result doesn't equal the mass of a carbon nucleus. That's because the binding energy of the nucleus plays a ro... | [
"Isn't Hawking radiation at the boundary layer of a black hole creating matter from energy?"
] |
[
"What is actually happening in my face when the left side of my nose is more congested than the other, then I lay on my right side and the congestion migrates to that side?"
] | [
false
] | I understand gravity is pulling mucus through to the other side, but I cant seem to visualize how that's actually happening -- is there no membrane? what consistency is the mucous for it to do what it does? It seems like even the most porous membrane would stop that. Boogers arent exactly flowing, and it doesnt feel runny either. Almost like a spongey slug walking back and forth between nasal cavities as I toss and turn. | [
"http://en.wikipedia.org/wiki/Nasal_cycle"
] | [
"There is actually a lot of communication between the paranasal sinuses, and they are actually divisions of a larger cavity. ",
"http://www.webmd.com/allergies/picture-of-the-sinuses",
"So the sensation you have the the mucus passes from one side to the other is true. The mucus is viscous, but it flows a lot b... | [
"https://www.youtube.com/watch?v=eiAx2kqmUpQ&feature=youtube_gdata_player",
"\nSauce explains it brilliantly"
] |
[
"Does the 4.54 billion year age of Earth mean the planet has orbited the Sun 4.54 billion times?"
] | [
false
] | Or is it just that old based on how many times it would have to orbit at our current yearly rate? We add leap seconds ever couple years, so I'm just wondering how much of an affect that would have over 4+ billion years. | [
"http://en.wikipedia.org/wiki/Year#Variation_in_the_length_of_the_year_and_the_day",
"Sun loses mass, year gets longer by 1.25 micro-seconds a year. This leads to the earth orbiting the Sun ~4.5405 billion times in 4.54 billion years."
] | [
"I've heard the days are slowing down because of tidal interactions with the moon. I hadn't heard the year was getting longer. Any links/arguments as to why this is the case? "
] | [
"Pb-Pb dates of comparably old materials (in meteorites) typically have errors of 1-2 Ma, well in excess of the 0.5 Ma noted above."
] |
[
"Where do you find the best and most informative coverage about the US and Stem Cell Industry?"
] | [
false
] | null | [
"Wired. Hands down. Their innovation blog is spot on."
] | [
"Regardless, very few publications (particularly of the major news corporations) have taken time to give perspective on what many of the tenets of stem cells.",
"Take pluripotency for example, it wasn't until I found his article through Forbes that I learned there was a discretion between full and partial pluripo... | [
"I have found Forbes does a good job of breaking down mid-high level science while incorporating excellent sources. John Farrell is one of my favorites."
] |
[
"Why do humans and most other animals have a soft \"underbelly?\" Why doesn't our rib cage protect our digestive organs as well?"
] | [
false
] | null | [
"The rib cage isn't just for protection. The rib cage's most important purpose is to inflate and deflate the lungs. The muscles between the ribs help them to expand and retract which brings air into and pushes the air out of the lungs. The diaphragm, which attaches to the inferior border of the rib cage, also he... | [
"Also if we had an abdominal section of the rib cage mobility would be greatly reduced. "
] | [
"There is no functional need for ribs below the diaphragm.",
"Exactly this. If the rib cage extended to cover our digestive system, we wouldn't be able flex our trunk, or bend at the hip. It is simply not bio-mechanically sound. It would affect our ability to bend over, squat down, sit up, have babies grow in the... |
[
"Does this image of a bacteriophage comes from an electron microscope or is it CGI?"
] | [
false
] | null | [
"It looks like a real SEM, but it does not look like a real virus. ",
"EDIT: Yup. DLC FIB on Si substrate. Real image, fake virus. ",
"http://geometrymatters.tumblr.com/post/55950708193/artificial-nano-t4-bacteriophage-t4",
" "
] | [
"Thanks! that make sense, cause it did look like a SEM image, but the other bacteriophage I saw where less shaped. ",
"So it's like a model? I found these words: \"diamondlike carbon (DLC) resonator by focused-ion-beam\". No idea what that means though :P"
] | [
"A focused ion beam is like a nanoscopic 3d printer. Except it can both add and subtract material. DLC is just the material that particular FIB machine uses to print with. "
] |
[
"When condoms are listed as 99% effective, is that per use? How is that number determined?"
] | [
false
] | If a condom is 99% effective every time you use it, eventually, the odds are pretty bad. If you and your partner have sex 100 times, the condom's effectiveness would be .99 or 37% effective. Or is the use of condoms 99% effective regardless of the number of times you have sex? That number seems to be arbitrary. | [
"besides the actual statistics (the 100 couples for 1 year thing) this number is likely made by lawyers, not scientists. even if they were 100% effective, no company would ever market something as 100% effective when the consequence of failure is having a kid."
] | [
"This questions comes from a misinterpretation of that statistic. It isn't that there is a 1 in 100 chance each time you use a condom that it might fail. Instead, it's something much weirder than that, but eventually I'll explain why it's really the only way we can measure this.",
"That 2/100 number (actually not... | [
"Condoms come along with a small information package that tells you what the failure rates are. Here is an example: \"Pregnancy rates for birth control methods. (For one year of use in the United States)\"",
"For \"Male latex condom\" it states 2% for \"Lowest Expected Rate of Pregnancy\" - so it means that if us... |
[
"Do veins grow in the same configuration in most/all people? That is, will my neighbor's veins branch in the same places/same way as mine?"
] | [
false
] | Obviously human bodies have variation, but most people are born with two eyes, two hands, ten fingers, etc. which are all in the same places. Does this apply to veins, too, or do they vary in the number of places they branch/particular places they branch? I guess this question can apply to other parts of the body, too, like the nervous system... | [
"The major vessels have a pretty much identical branching pattern in terms of where and how often, which is a pain in the arse to learn in anatomy courses, believe me. Same holds for nerves. If you look at the small vessels supplying the tissue directly, things get more random, again for innervation."
] | [
"Consider them much like hands and eyes: at a large enough scale, they are very similar, but when you get to finer scales (fingerprints, the structures in the iris, fine veins and capillaries), they become much more unique. A forensic anthropologist in the UK has performed research on the individuality of vein patt... | [
"I’d just like to add that there are areas in the body that are prone to more variation than others, the forearm for example has a few different vein patterns which are quite common, but as the others said, most of the important vessels don’t variate much"
] |
[
"In Layman's terms, how do the new RTX graphics cards calculate the path of light rays?"
] | [
false
] | null | [
"The maths behind raytracing isn't too complex. You work out where a beam of light hits a surface, and then you work what direction it bounces to etc. The problem is that you have a ",
" of rays of light to deal with, and that gets computationally expensive.",
"So what you do is you run the calculations in ",
... | [
"i'd like to add that following ray bounces from light source to camera still is not cheap so instead they follow rays from camera to light source"
] | [
"Indeed. This is primarily done so the GPU doesn’t have to worry about rays that end up out of sight of the camera."
] |
[
"Why are African Americans usually lighter skinned than Africans?"
] | [
false
] | [deleted] | [
"My thought is that it is a result of interbreeding with light skinned people",
"Yup.",
"(",
"ref",
")"
] | [
"What makes you think that this is actually true? I'm not saying it isn't, but has this been approached scientifically?",
"Also, it is possible and likely that the genetic diversity throughout the African dark-skinned races is much much larger than in America. It would make sense that the slave trade \"imported/k... | [
"Sounds right. I just wanted to make sure I've considered the whole picture (or at least a bit more than just the focal point) and clarified that there isn't just one skin color throughout Africa before jumping the gun."
] |
[
"What are the molecular differences between milk, creme, butter, and cheese?"
] | [
false
] | What are the molecular differences between milk, creme, butter, and cheese? Are there chemical differences too? | [
"Milk is a colloid composed mostly of water and fats and also calcium and protein. Cream is an oil in water emulsion, meaning more water than oil. It's basically just the milk fat clumping together. Butter is the opposite, a water in oil emulsion. Take most of the water out of milk and leave the fat, that's butter.... | [
"I apologize for not making my question more detailed, but I am curious more about specifics. I understand the general differences between the four. I understand the processes of production for all of them as well as their basic fat/water/protein relationships. That much i've learned from my own reading and working... | [
"I believe most of the calcium is contained in the proteins. Not that it makes much difference in then end though."
] |
[
"How do electrical storms affect cell phone reception?"
] | [
false
] | Today I was having trouble with cell phone reception over the course of several hours, and postulated that it was due to a large storm passing by. Would a storm block cell phone reception and if so how? | [
"The electrical storms generate a lot of random radio waves, which decrease dramatically the ",
"signal_to_noise ration",
". An example of it would be whispering in a silent room vs whispering on high way, you can hear it perfectly in the room but not on high way."
] | [
"How are the radio waves generated? Buildup of EM-spectrum energy that's discharged via lightning, right?"
] | [
"When a large diffrence in the electrical charge of the ground and the cloud (or cloud to cloud) builds up, large amounts of charged particles can break through the atmospheric barrier and flow between the air and ground. This mass transfer of charge radiates much like an antenna would."
] |
[
"How can things with no mass make up everything that has mass?"
] | [
false
] | Basically, how can elementary particles with no mass, electrons and quarks for example, make up everything that has mass, such as protons and neutrons? | [
"Quarks",
" and ",
"electrons",
" ",
" have mass. However, the mass of the individual constituent quarks is ",
" than the total mass of the particles they make. The reason for this has to do with binding energy, but this delves into quantum chromodynamics which I don't really know anything about; I hope s... | [
"This is a good YouTube video by Veritasium called \"",
"Your Mass is NOT From the Higgs Boson",
"\" which gives a nice heuristic explanation of how baryons get their mass."
] | [
"Interesting fact: the top quark weighs about as much as a tungsten atom. It is by far the most massive elementary particle."
] |
[
"What happens to the debris we inhale on a daily basis? do we absorb nutrients from the air?"
] | [
false
] | [deleted] | [
"Dust and other irritants are not absorbed into the bloodstream nor otherwise broken down in one's respiratory system. They are captured by small hairs and mucus and expelled out the way they came through coughing, sneezing, and picking. With the lungs some may also be swallowed and dealt with by the digestive tr... | [
"You're right that we don't have that dust in your lungs, as the gas exchange areas of the lungs (alveoli in particular) are very, very delicate and prone to infection. We don't want any debris in there. ",
"What happens instead is that, as you say, any debris we inhale is caught in mucus. We then have what is te... | [
"Your respiratory cilia ",
"move mucous toward the throat",
" where it is swallowed."
] |
[
"Why does a camera measure luminance in a scene and not illuminance?"
] | [
false
] | I always thought that a CCD or CMOS sensor measured how many photons had hit a pixel within a given time frame. This seems to suggest that illuminance is being measured, if the pixel has a certain area its value will be proportional to the illuminance hitting it. However i understand that a camera is sensitive to Luminance, and is demonstrably so by moving it further away from a light source, where the light source looks smaller but has the same "brightness". How is this? | [
"The key here is to note that the camera is measuring the light coming from the scene it is taking a picture of. It thus measures the amount of light being reflected off the object from a light source; this is luminance. Measuring the total amount of light hitting the object, reflected or otherwise, would be illumi... | [
"The amount of light passing through the lens and aperture should be directly proportional to the luminance of the scene, so theoretically yes the illuminance on the CCD should be proportional to the luminance of the scene. If you have no lens or aperture but simply a CCD it is directly measuring how much light is ... | [
"So the CCD sensor is a measure of the illumination hitting it. However the illumination hitting it comes from the lens and not the scene, so is the illumination hitting the CCD proportional to the luminance of the scene when there is a lens/aperture? ",
"If instead of a camera i has a ccd with no lens and no ape... |
[
"Why don't freight trains use turbine engines?"
] | [
false
] | Freight trains in the US use diesel-electric drive trains where the engines act as a generator that then drives electric motors. These trains are supposedly extremely efficient, with a commonly-cited figure of 400 mpg per ton. However, I'm operating under the assumption that turbines are the most efficient way to produce electricity as they're used to produce electricity for the grid. If this is the case, then why aren't trains using turbines, since they're trying to turn fossil fuel into electricity at peak efficiency? If it's not, then why do power plants not use diesel? | [
"Because trains do a lot of idling as well. Turbines are ungodly inefficient at low speed (power)",
"There are several examples of turbine locomotives though. The opitomy of which were Union Pacific's General Electric turbine locomotives (GTEl's). Flooring 8500hp (and by some accounts capable of up to 10k.)",
"... | [
"This is super interesting, thanks! Btw, the word you're looking for is epitome, not opitomy."
] | [
"Power plants work differently. They use heat to generate high-pressure steam, and send that through a series of turbines to extract work from it. That process is very efficient. For a gas turbine engine, it's the expanding gases from the combustion itself that turns the turbine. While capable of generating hig... |
[
"Will we be able to feel or notice when the andromeda galaxy collides with ours?"
] | [
false
] | null | [
"Assuming you're anthropomorphizing The Milky Way, we will feel it. The individual solar systems not so much. The space between the stars is so vast, that the stars will just glide through each others neighbourhoods.",
"\nOn astronomical time scales, there will be stars thrown about all over the place, but on civ... | [
"The andromeda galaxy will collide with ours in about 4.5 billion years (4.5 billion years is also the age of the Sun. Coincidence? yes). By then, it seems unlikely that any humans will still be around. Even if we spread across the galaxy somehow, presumably we'll have evolved into something we wouldn't recognise a... | [
"We won’t be here. And likely, neither will any other species alive today. 4 billion years of evolution molded us to the species that we are today, and 4 billion more is going to do the same. ",
"As for your question, maybe someone like ",
"u/astrowiki",
" could comment about gravitational effects or whate... |
[
"What are these lights that shine on the astronauts when they get interviewed?"
] | [
false
] | Every time I watch one of Commander Scott Kelly's interviews, I see a bunch of laser looking lights on him. They don't appear to have a pattern and they seem to be shining around the room as well; you can see them on the cameras too in the following pictures. Apologies for the low quality images, but you should be able to see the lasers in any interview with Commander Scott Kelly. Without circles: With circles: Thanks in advance! | [
"Cosmic radiation damaging the CCD sensor in the camera in certain spots where it hits."
] | [
"A paper describes this exact problem: ",
"Influence of Terrestrial Cosmic Rays on the Reliability of CCD Image Sensors ",
". ",
"Or you can read this ",
"astronomer's web page about general imaging nonsense",
"."
] | [
"Not so much \"explosions\" as they are \"photonic booms\", the light equivalent of a sonic boom. ",
"Sonic booms happen when an object creates sound waves while traveling faster than the speed of sound in the medium it's traveling in. ",
"Likewise, light travels different speeds in different mediums. The only ... |
[
"Will a planet(s) eventually form in the Kuiper/Oort Cloud?"
] | [
false
] | [deleted] | [
"Yes, the asteroid belt is also very low density. The whole thing has only a few percent of the mass of the Moon, and that's spread out over a gigantic area. ",
"Also yes, Jupiter prevents asteroids from doing very much accumulating."
] | [
"Yes, the asteroid belt is also very low density. The whole thing has only a few percent of the mass of the Moon, and that's spread out over a gigantic area. ",
"Also yes, Jupiter prevents asteroids from doing very much accumulating."
] | [
"No, there's very little matter out there and it's ",
" low density, and the Kuiper Belt can't really create large accumulations of bodies because the gravitational influence of Neptune will perturb orbits too much.",
"The Kuiper Belt has really low density, but it's ultra-crowded compared to the vast empty exp... |
[
"If we turned off every electrical light in the whole world, would light pollution go away instantly, or take time?"
] | [
false
] | null | [
"Light would dissipate at the speed of light - so it would appear instantaneous to humans to the extent that photons would stop bouncing off of the air and traveling back to eyeballs in a fraction of a fraction of a second. ",
"You probably wouldn't immediately see a wonderful dark sky, though, because human nigh... | [
"In the big East coast blackout of 2003, I hope people took the opportunity to look up at night. Truly dark skies are absolutely mind blowing. It's safe to think that a significant portion of the population has never seen the milky way with the naked eye."
] | [
"I remember the 2003 blackout. It was too cloudy where I was to see the milkyway. What a waste"
] |
[
"Is it possible to refine iron out of Hemoglobin?"
] | [
false
] | I've done some snooping around the net, and I found that there is about 5.5 liters of blood per person. Take all the red blood cells in 5.5 liters, times 280 million hemoglobins in 1 cell, times 4 hemes per hemoglobin, and you get ~2.7 grams of iron in a person. Is there any way to refine the iron out of blood? I don't care if it's feasible or even sensible, only if it's possible. If so, how would it be done? Thanks! PS:Not a serial killer! I just had an idea for a character with a vendetta. This is all for theory. | [
"Most definitely. Part of it has already been done in alchemical history, though extracting iron was not the goal.",
"Prussian blue",
" is a paint pigment that's first synthesized in the 18th century. It is an iron compound complexed with cyanide ligands. It was accidentally discovered when a paint maker used m... | [
"Interesting question. Possible? Yes. Easy? Nooooooo. ",
"If you could purify all the iron ions from the heme, the problem you'd still have to deal with is a very energy-intensive chemical reduction reaction to convert the Fe",
" to Fe",
" This is basically un-rusting the metal and takes a lot of energy, th... | [
"There would be many ways of doing that. The most straightforward method, although not likely to be anywhere near the most efficient, would be mass spectroscopy (something like ",
"ICP-MS",
". Which, in simple terms, entails blasting the molecules apart completely into atoms and then sorting the atoms according... |
[
"How much harder would it be to get to another planet if the destination planet was orbiting in a plane perpendicular to ours?"
] | [
false
] | null | [
"You play KSP, don't you?"
] | [
"It would depend on a lot of things -- ",
"how fast the planet is moving (relative to the star)",
"how strong the planet's gravity is",
"what other planets are available for ",
"gravity assist maneuvers",
"In some gravity-assist scenarios, you could match a polar orbit quite cheaply. The ",
" spacecraft... | [
"Not significantly. The added delta-V cost would be on the order of planetary orbital velocities, tens of kilometres per second. But to achieve interstellar travel in a reasonable timescale, you would already want to be doing at least hundreds and preferably thousands of kilometres per second."
] |
[
"Can pathogens actively target wounds, or are infections totally random?"
] | [
false
] | Can pathogens detect open wounds and attack them, or are the infections we receive totally random happenings? | [
"There are also the bacteria which are part of your natural flora to consider. Staphylococcus aureus is a nonpathogenic bacteria until it is given the opportunity to multiply more rapidly (in a wound) than it normally does on your skin where it is not exposed to as much sensitive tissue. "
] | [
"Not really. Bacteria on fairly dry surfaces don't move fast, and there's also the skin's natural flora to contend with. Usually, bacteria are carried in by another, faster moving object like a hand or paw fiddling with the wound or contaminated materials getting into the wound. Viruses aren't motile. I really ... | [
"Yes, that's true. I overlooked that; thanks for the correction. "
] |
[
"Is it possible to become addicted to a substance when unaware of taking it?"
] | [
false
] | Say I have Addicting Substance A (known to cause both physical addictions and mental dependency). It's effects are euphoria, peaceful feelings, and a strong antidepressant. I secretly administer this substance to Subject A through a variety of ways; in his food, powder on his clothes, piped in through vents, etc (so he doesn't get attached to a single carrier, ie from a cigarette). Will Sub A become addicted? Additionally, he give AddSub B to Subject B. It is also physically and mentally addicting. However, it's single effect is that is slowly lowers cholesteral, no other side effects. It is administered in a similar fashion. Will Sub B become addicted as well, even though there's no feelings, good or bad, present? Lastly, AddSub C and Sub C. Addicting, anonymous delivery. This drugs effects are minor nausea, dizziness, and a depressant. Would Sub C become an addict even though it's a complete downer? | [
"Physical addition is different from concious addiction.",
"A human body will certainly become \"addicted\" to substances whether they are aware that they are taking them or not. This \"addiction\" is more of an acclimatisation, simply becuase the body gets used to having the substance, so it will go through any ... | [
"in his food, powder on his clothes, piped in through vents, etc ",
"Through the umbilical cord is the usual method for this experiment."
] | [
"At first I was like \"WTF, who would approve that experiment?\" Then I realized what you were saying and got depressed. "
] |
[
"I've heard that if you kno k out a tooth, it's possible for a dentist to put it back. Could you transplant teeth from one person to another? "
] | [
false
] | null | [
"The process is called ",
"dental avulsion",
", which is the immediate replacement of a knocked out tooth. However, like reattaching limbs or other organs, time matters, and how the tooth is stored really matters.",
"Placing another person's tooth might be possible (I couldn't find anything that supported tha... | [
"Placing a knocked out tooth back into its owners body is difficult enough, you've got about 5 minutes to wash it off with tap water, get it into a glass of milk and rush to see a dentist, after about an hour we will generally not try reinserting a tooth due to necrosis of the periodontal ligament cells. Given all... | [
"I thought you that referred to implanting false teeth? "
] |
[
"Why is there glycine in Western Transfer Buffer?"
] | [
false
] | Grad student here that does western blots everyday. But I don't know why every protocol which I can find calls for the addition of glycine in the Western Transfer Buffer. Before I get inundated with people mentioning the process of SDS-PAGE and glycine's role in stacking; Western blotting is different, and I don't know why we use glycine when there is no change in pH. | [
"Post-Doc in biochemistry here. I looked up the section on protein blotting and immunodetection in \"Methods in Enzymology\" Vol 182 pp 681-682.",
"\"",
" The choice of buffer composition depends on the types of gel and membrane selected. The procedure of ",
"Towbin",
" as modified by ",
"Anderson",
" s... | [
"Honestly, probably just for buffering since as you said, there's no pH change. It's not doing what it does in the sds-page, that's for sure."
] | [
"Hmm wow, thanks. I had given a literature search a college try but didn't find anything this satisfying, thanks. ",
"We currently use MeOH in our buffer, I may try excluding it."
] |
[
"Chickens are encouraged to eat as much as possible. Why wouldn't the excess calories just turn into fat? Especially since the goal is to build more muscle."
] | [
false
] | It sparked my curiosity several weeks ago when watching a mention of this on the Colbert Report. And today it was turned into a front page post on . The issue is that chickens are fed caffeine amongst other methods of stimulation. All of it contributes to the chickens eating more than they would normally. The idea is to get chickens to grow and mature faster. All the eating in humans just causes us to accumulate fat; why isn't this mirrored in the chickens? | [
"True, but the antibiotics they use promote growth."
] | [
"No, I have a BS in (micro)Biology, so I am familiar with what you're saying. ",
"The question that I am asking is why are the chickens building larger muscles vs fat deposits. The larger food intake is causing them to mature to be fully grown faster. In mammals, we just get fatter. The former just seems like... | [
"(I did not downvote you)",
"The USDA (can't say the same about other nations) does not allow hormones to be used in poultry. Go to your local grocery store and look at their chicken. A lot of them will boast about how it is all natural and does not contain hormones (added). Well that is because it would be il... |
[
"How do spacecraft get rid of excess heat?"
] | [
false
] | I've read the but finding visuals would also be nice. Are there also hypothetical methods of venting heat in space that we currently don't have the technology for? | [
"The only way to get rid of heat in space is through radiation. In addition, temperatures across a spacecraft can vary tremendously and can range from +70C to -40C just from one side of the spacecraft to another. So there are a few different things that we can do to mitigate temperature variation and keep our compo... | [
"The only way to get rid of heat in space is through radiation.",
"You ",
" heat something up and chuck it out an airlock, but of course that's not very sustainable."
] | [
"In ",
"this picture of the ISS",
", the large white panels pointing down from the main fuselage of the station are radiators. Ammonia coolant is circulated through the station and then pumped to the radiator panels, where the heat is rejected into space.",
"Since there's no air in space, there's no medium fo... |
[
"Can a supernova remnant coalesce back into a star?"
] | [
false
] | If you take something like the crab nebula, could the expanding gas cloud start to collapse back in on itself and form a new star? Or would the shock wave and/or neutron star there prevent that from happening? | [
"From the Remains, New Stars Arise\nThe dust and debris left behind by novae and supernovae eventually blend with the surrounding interstellar gas and dust, enriching it with the heavy elements and chemical compounds produced during stellar death. Eventually, those materials are recycled, providing the building blo... | [
"So the final 'form'of a supernova is basically a tiny nebula, capable of forming several new, smaller stars and brown giants?",
"Nope. The supernova particles move outward and can't coalesce together as they thin out. What ",
" happen is, that these particles hit other gas clouds in the vicinity and cause new ... | [
"The short answer is no, not really. The expanding remnant is moving much too fast for that to happen. However, there is a case for a certain range of high-mass stars where some of the supernova ejecta does fall back on to the left-over neutron star a short time after the explosion and cause it to collapse into a b... |
[
"Do objects actually have a defined color? Is it defined on what color the light source is?"
] | [
false
] | For example, my bed sheets are white. I can see that they are white under normal sunlight. However, if I were to take a red light bulb and illuminate my room in red light, the sheets become red; they changed color. I believe you could do that with any other color, like my blue shirt under the red light would look different, my yellow pencil will be different. Are we so used to the color of things under natural sunlight that we consider those colors to be true, or is the color of an object simply based on what color the light source is? I hope this makes sense and I believe I am thinking too much about this, but I'd like to hear the explanation anyways. | [
"Your bed sheet is white. What does that mean? Simply, your bedsheet reflects all colors back at you. When you shine white, it reflects all the white back and you see white. What if you shine red? Well there's only red light now, and it reflects the red light back, so it appears red to you.",
"Now let's think of ... | [
"The problem with that, though, is to then wrongly assume that because wavelengths are real, the color we see matches wavelengths linked to that color. When you see \"orange\" on a computer screen, it's not light which is ~630nm, it's an interpretation of 3(ish) wavelengths combined to simulate \"the color orange.\... | [
"Colour is a property of your perception. It is not a physical property inherent to an object. What ",
" inherent to the object is its absorption spectrum - the object absorbs specific wavelengths of light more than others - or other scattering phenomena."
] |
[
"How precise are large astronomical telescopes (e.g., Mauna Kea)? Does the surface have to be precise within a fraction of the wavelength, or is there more margin for error?"
] | [
false
] | null | [
"They have to be precise within a fraction of a wavelength - to get the full resolution and light collection, you want light from the whole mirror to add constructively.",
"ELT with its (segmented) primary mirror of 39 m diameter gets mirrors ",
"smoother than 10 nm",
" or 0.25 ppb - supported ",
"at 20,000... | [
"Yes, for a reflecting telescope a good mirror is figured (shaped) to within a fraction of a wavelength.",
"The shape of the mirror can be tested optically using very simple equipment. The Foucault knife-edge test requires a lightbulb, a pinhole, and a razor blade. Modern large telescopes are tested with much mor... | [
"Typical optical mirrors are already at a fraction of the wavelength in surface flatness (1/4 to 1/10). They are probably at least in those orders of surface roughness, because they not only need to be large to collect more light but also to be precise in order to identify details. The exact precision will depend o... |
[
"Why does water form these tiny air bubbles on the side of a glass bottle if it is allowed to sit still for a while?"
] | [
false
] | null | [
"Most water has various gases dissolved in it, like oxygen or carbon dioxide. The warmer the water is, the less gas it is able to hold--that's why your soda foams up so much more when it's hot than when cold. Also, the less pressure the water is under, the less gas it's able to hold--that's why your soda foams up... | [
"And to supplement this post even more: they form at the side of the wall because the gas adsorbs there for energetical reasons. It \"costs\" less energy for a nucleus (here a tiny bubble, elsewhere a tiny crystal) to grow at a surface. This is called heterogeneous nucleation. In case they would form in water it is... | [
"And to supplement this post even more: they form at the side of the wall because the gas adsorbs there for energetical reasons. It \"costs\" less energy for a nucleus (here a tiny bubble, elsewhere a tiny crystal) to grow at a surface. This is called heterogeneous nucleation. In case they would form in water it is... |
[
"Could someone recommend a good video tutorial on the chemistry of molecules? I'm taking general biology and might fall behind here."
] | [
false
] | [deleted] | [
"http://www.khanacademy.org/#chemistry"
] | [
"And you could also go check out ",
"the biology section",
" if you have trouble at any point in your class. I haven't watched any of those ones (or the chemistry section for that matter), but I did use the probability and statistics sections for brush-up not too long ago, and they are overall, quite good."
] | [
"Can't upvote this enough."
] |
[
"What percentage of sea level rise is from the thermal expansion of water vs. melting polar ice?"
] | [
false
] | null | [
"that's a rise of about 4 m",
"This seems high, so I redid the calculation myself. Yes, recent research has given more refinement to how climactic change has affected water at various depths, and the distribution is far from uniform, so that caveat still stands, but using some basic assumptions:",
"Thermal expa... | [
"Let's say the average seawater temperature is 15 degrees. If it warms by 1 degree C you get about 0.1% expansion. So for a water column that is about 4km deep (average ocean depth) that's a rise of about 4 m. By comparison, if the icecaps completely melt you're looking at something in the order of about 60 - 65 m ... | [
"Yep, thanks. I dropped a zero on my expansion coefficient"
] |
[
"What is the mechanism that causes my heart rate to increase with physical exertion?"
] | [
false
] | null | [
"It's a brain signal, you have the SA and the VA node that control the rate at which the heart pumps. Your brain simply detects it is exercising and needs more oxygen and less waste products. When you're exercising, you need more oxygen and you are also generating more waste, but you already know this. Heart beat i... | [
"You have a number of receptors in blood vessels (aorta and carotid) and in the brain itself which send signals to the cardiac control centre in the brain stem. These receptors monitor the pH of the blood (high carbon dioxide levels = low pH) and pressure of the heart beat. Your heart will beat faster if there is m... | [
"That's what I was looking for. Thanks!"
] |
[
"If a balloon filled with air goes deep enough in the ocean, will it not float up?"
] | [
false
] | To further explain this, from my understanding of buoyancy, what creates the buoyancy is the fact that the less dense material displaces more of whatever the surrounding material so much so that displaced material weighs more than the material doing the displacing. So my question is, lets say I have a normal balloon filled with normal air. And I were to bring this balloon to the bottom of the ocean, or to a depth that the pressure of the ocean is so much so that the air inside the balloon is compressed to a size where the amount of water displaced, weighs less than the balloon. What would happen then? Would it just sit at that depth? Would it sink? or would it for some reason I dont know of, float back up to the surface? | [
"You would need to be approx. 4.85 miles under water for the density of air to equal the density of water. Any higher and the balloon floats, any lower and the balloon sinks. ",
"I did this calc. quick using this ",
"http://www.calctool.org/CALC/other/games/depth_press",
"\nand this:\n",
"http://www.engin... | [
"The air would rapidly dissolve into the surrounding water and diffuse outward. ",
"Depending on what type of rubber the balloon was made of, the fragments would likely slowly float upwards."
] | [
"The air would rapidly dissolve into the surrounding water and diffuse outward. ",
"Depending on what type of rubber the balloon was made of, the fragments would likely slowly float upwards."
] |
[
"Is it true that science knows only a fraction of the molecules present in, say, a grapefruit?"
] | [
false
] | How is this recognized and dealt with by the scientific community? Is it important? Is it only necessary where notable side effects have been observed? | [
"In order to know they are there you must measure them or prove beyond a reasonable doubt that it has to be there for something to occur. Even then, some are transient, others are just indistinguishable or no one has cared enough to make a reasonable effort of measuring it. Companies spend inordinate amounts of m... | [
"This isn't true. There are very few biological molecules that aren't well known, most of them are only trace amounts, especially in something relatively simple, like a fruit."
] | [
"Partially correct. We more than likely know of the molecules that are in a grapefruit but it doesn't mean we actually know if they are there.",
"As a guy who is building a business designing instruments to help detect these things it is somewhat of a big problem. These kind of systems are incredibly complex an... |
[
"Are GMOs generally unsafe?"
] | [
false
] | Here in Germany (actually a lot of places in Europe) we have movements that want to completely ban GMOs. They claim that GMOs are generally unsafe because the undestanding of how genes work etc. isn't developed enough and we can't foresee any side effects, even after testing the crops/plants/whatever. They fear that the (probably harmful) organisms will spread uncontrollably. Now, how much of that is true? Are they just technophobic? Also, when will I be able to combine pigs and spiders so that I can get 8 legs per pig? (You don't have to answer that ;-)) I'm not talking about patents, about big business and so on, I'm really just interested in the scientific aspect of the issue. | [
"First off, GMO is a broad category. It is often (wrongly) used interchangeably with transgenic, which is different. A GMO, or genetically-modified organism, is any organism that has had its DNA modified directly without using breeding. Transgenic organisms are GMOs where the new DNA in the transgenic organism is f... | [
"Still testing, no proof of safety hazards.",
"Warning: transgenic plants may contain alllergens. There are brazil nut proteins that are moved into other organisms for purposes of pest-resistance and/or herbicide-resistance. Test for allergens in whatever way you know how before consumption of suspected GMO.",
... | [
"As I said, I'm only interested in the scientific aspect, not legal issues like DRM or patents. That's a political problem.",
"Can you elaborate on your first three sentences though? If they're poorly tested why have there not been any health problems etc.? Have there been any that I'm not aware of? Why are they ... |
[
"Can we inherit intelligence?"
] | [
false
] | I mean as if 2 parents with IQ around 120 have a child will the child have an IQ of 120 or More? | [
"Heritability of intelligence has been measured, but the outcome is strange and I actually think that's because of a fundamental problem in equating IQ to intelligence. It would really be far more accurate to say that the heritability of IQ has been measured. ",
"Nonetheless, ",
"this study from last year",
... | [
"See my responses in this recent thread:",
"https://www.reddit.com/r/askscience/comments/3g4mtq/do_humans_with_bigger_brains_have_more/"
] | [
"Nonetheless, this study from last year measured a number of aspects of intelligence as a behavioral trait. I think the most interesting finding here for me personally is that assortative mating for intelligence is greater than any other behavioral trait and also greater than the measured physical traits! Which imp... |
[
"Pretend for a moment we are mining resources from other worlds and bringing them to Earth. How would this additional mass affect our orbit?"
] | [
false
] | At what point would we have brought so much extra mass to the Earth that the planet's orbit around the sun or in relation to the moon/other bodies is fatally affected? These are the things that keep me up at night. | [
"It would not affect the orbit around the sun. It probably wouldn't affect the moon either, unless we brought a shitload of mass back. All the asteroids in the solar system weigh less than a percent the mass of the Earth, so that would be difficult."
] | [
"Is that a metric or standard shitload? (I'm breaking the rules but this was nearly irresistible.)"
] | [
"The earth already gains between 40,000 and 80,000 tons of mass each year from cosmic dust and meteors, and that has no measurable effect on our orbit. And it has been doing this for billions of years. In other words, more extra mass than is even worth considering. "
] |
[
"When people say \"I can see for miles,\" how would this actually translate?"
] | [
false
] | [deleted] | [
"The equation to find out, depending on how high your eyes are off the ground, is this. ",
"Distance(miles) = 1.323 * Sqrt(eye height ft)",
"Distance(kilometers) = 3.57 * Sqrt(eye height m)",
"so if your eyes are at 6 feet you can see a horizon line at about 3.24 miles. ",
"Source",
"Btw this only works f... | [
"The distance to the horizon is based mainly on the height of the viewpoint.",
"For an unobstructed view to the horizon, go to the ocean, for a 5'7\" person standing at sea level, the horizon is 3.1 miles away.",
"For a bunch more explanation and math, check out the ",
"Wikipedia article on the Horizon",
"E... | [
"Others have answered quantitatively so I won't bother, but just for interest, you don't even need a theoretical smooth Earth to imagine this, it's a very visible effect on the ocean. If you look at a distant sailboat for instance, there is a point where you can see the sails but the hull of the ship lies below th... |
[
"On average, do you lose more weight through respiration or pooing/peeing?"
] | [
false
] | null | [
"So the primary part of respiration that would be \"losing weight\" is co2 from respiration.",
"1 mol of co2 is gonna take up about 25L and weight about 50g. At normal tidal volume of 500 mL and 12 breaths per minute, you are expelling about 300 mL of carbon dioxide per minute, or 18L per hour. Let's call it 40... | [
"Thanks!!"
] | [
"Not my field, but I was under the impression that you exhale a lot of water vapor as well. That should be fairly heavy, right?"
] |
[
"What would large quantities of protons, neutrons, and/or electrons look like?"
] | [
false
] | For example, the inside of Neutron stars is essentially just neutrons correct? What would it look like if we were able to take a knife and cut that star open and let the neutrons spill out? | [
"For example, the inside of Neutron stars is essentially just neutrons correct?",
"It's actually a bit more complicated than that - see the cross-section diagram ",
"here",
". But sure, neutron stars have a lot of neutrons inside them.",
"What would it look like if we were able to take a knife and cut that... | [
"That short decay time only applies to free neutrons, i.e. neutrons that are not bound inside a nucleus. (I've edited my previous comment to clarify.) ",
"Also, neutrons are produced in various atomic reactions, so the supply of neutrons is not fixed. Such reactions commonly occur in stars, and along with prod... | [
"You just made me realise, if neutrons have a half life of 14 minutes, how do they continue to exist after being formed? It seems to me they should decay away within hours. "
] |
[
"Why are men's testicles so sensitive?"
] | [
false
] | null | [
"Doesn't getting punched/touched in any organ feel sensitive? Like your kidneys? We just don't notice other organs being sensitive because they are not exposed. Just a guess but seems possible. "
] | [
"There's always an exception to things so why can't skin be in this case? And skin is relatively sensitive in some places like being ticklish and sensing heat? Like I said, I literally know nothing about this I'm just taking shots in the dark. "
] | [
"You're saying you shoot blanks?"
] |
[
"In unltrasonics an increase of 6Db will double your signal. How are the two correlated?"
] | [
false
] | [deleted] | [
"In general, dB is a ratio between two power levels. In general, the formula is Ratio(dB)=10 log(P1/P2). However, it is often possible to use voltage instead of power. In this case (considering that P=(V",
" / R), the ratio in terms of voltage = 20log(V1/V2). ",
"As a result, an increase of 6dB for voltage (whi... | [
"Since the decibel scale is logarithmic, and the ratio between two sources (in your case ultrasound) is equal to 10",
" , where x is the number of decibels you increase, you can see when you increase the output by 6dB, the amplitude of the ultrasonic wave approximately doubles."
] | [
"See my comment below. If power increases by 3 dB, then power doubles (voltage increases by square root 2). If power increases by 6 dB, then voltage doubles (power increases by 4x). Both are equivalent, you just have to be clear what formula you are using. OP is using voltage (20 dB change in power is 10x change in... |
[
"Is there a way to obtain a perfectly random natural number between 1 and ∞? If so, if you take the average of 10.000 purely random numbers, what result do you get?"
] | [
false
] | [deleted] | [
"No. There is no uniform probability distribution on a countably infinite set. Such a distribution would have to satisfy p(x) = p for each ",
". Hence p+p+p+... = 1, which is impossible."
] | [
"Nope. If you get rid of the logical framework surrounding how we count/analyze numbers, you can't cherry-pick some rules just to make your nonsensical result sound reasonable. ",
"Well, you ",
", but it would give arbitrary results. You decide your first principles, and that determines your result. It's pseudo... | [
"Nope. If you get rid of the logical framework surrounding how we count/analyze numbers, you can't cherry-pick some rules just to make your nonsensical result sound reasonable. ",
"Well, you ",
", but it would give arbitrary results. You decide your first principles, and that determines your result. It's pseudo... |
[
"What color does the human eye track the best?"
] | [
false
] | So say you had a dot moving around, what color dot would the human eye be able to follow and react to the fastest and most accurately? EDIT: MERRY CHRISTMAS | [
"a dark dot on a bright background or a bright dot on a dark background; the part of the visual system that senses achromatic contrasts is faster than the part that senses chromatic contrasts.",
"ultimately the bright dot would be easier to follow if you wanted to go to the limit of \"dot\" - an infinitesimally s... | [
"The human eye response is most sensitive in the green, peaking around 555nm. If these hypothetical colored dots were all of the same intensity, a green dot would appear the brightest. Not sure how perceived brightness affects tracking, hopefully somebody with knowledge in that area can weigh in."
] | [
"The color is called chartreuse; and yes, I believe that's why they go with that color.",
"Fun side note, Washington State Patrol had a bunch of ford tauruses one year that were a god awful shade of purple. And they are goddamn invisible if you aren't looking for them, they are the exact opposite of chartreuse."
... |
[
"Can mRNA vaccines like those made for covid 19 be made for bacteria as well?"
] | [
false
] | null | [
"If I’m not mistaken, mRNA vaccines for covid 19 is for the body to produce antibodies against the pathogen. So it shouldn’t matter whether or not the pathogen is bacteria or a virus. Someone correct me please?"
] | [
"If I’m not mistaken, mRNA vaccines for covid 19 is for the body to produce antibodies against the pathogen. So it shouldn’t matter whether or not the pathogen is bacteria or a virus. Someone correct me please?"
] | [
"not necessarily, some of the immunogenic portions of bacteria are not proteins, they are sugars. mrna vaccines tell the human body to make an immunogenic protein. but they can't tell the human body to make a uniquely bacterial sugar.",
"https://www.breakthroughs.com/impacts-innovation/vaccines-fight-sugar-coated... |
[
"Why does camphor sublimate? What property of it enables it to go from solid to gas?"
] | [
false
] | Are there any other solids like camphor? | [
"The liquid phase is basically when something becomes amorphous and mobile. Meaning the molecules are moving about and aren't in any fixed crystal structure any more, but at the same time they're still attracted to each other to the extent that their thermal kinetic energy isn't enough to cause them to fly apart co... | [
"Here",
" is a simple phase diagram. The X axis is temperature, and the Y axis is the pressure of the system. It shows you what phase the substance is at at your temperature and pressure. Some substances at certain low pressures do not become liquids. Likewise, at very high pressures most substances will neve... | [
"Anything can sublimate. All that is necessary is for its vapor pressure to exceed the applied pressure ",
" for the temperature to be below its melting point. This is a weird requirement, because vapor pressure goes down with the strength of the intermolecular forces through which the molecules are interacting, ... |
[
"If you didn't know about nuclear fusion, how would you attempt to explain why the sun is hot?"
] | [
false
] | Methinks it a mystery! | [
"erroneously"
] | [
"Reciting from memory here but here it goes:\nIndeed before we did know about nuclear fusion, why the sun is hot was a pretty big mystery. At the time the best theory was that it was still releasing energy from it's formation (energy from gravitational potential), but this would only be able to power the sun for up... | [
"Historically speaking they ",
" assumed a chemical source for powering the sun, and used those few thousand year figure as the age of the universe, further reinforcing the bible version of events. A bit of circular reasoning perhaps, but it must have seemed viable at the time."
] |
[
"Is there a theoretical 'maximum' to how loud a sound that room temperature / sea level air can reproduce without distortion?"
] | [
false
] | It would seem to me that since sound is a mechanical wave and rarefactions can't get any 'stronger' than a vacuum, there would be a limit. But I can't figure out how to compute it in SPL. Also, I'm curious about the heat that would produce, though I suppose that would be highly frequency dependent. | [
"Eventually you get something called nonlinear propagation where the air is squished so much that it changes the squishiness."
] | [
"There certainly is, you can't produce anything you'd call \"sound\" after 194.094dB due to the waveform being clipped at 0 pressure, after this you just get shockwaves. "
] | [
"Sound waves are pressure waves. When we pressurize air we effect temperature. So I think your question is flawed since it sounds like you want to know the answer to you question given a fixed temperature and pressure. If you relax those constraints, then we can start thinking about extreme examples of sound p... |
[
"How do strong acids \"eat through\" things?"
] | [
false
] | Just wondering what the chemistry is here. I know that acids are compounds that either donate protons or accepts electrons, but I'm not sure how that results in the effect of eating through stuff. Why is it almost a universal effect for strong acids to eat through things? Can bases do the same thing, and if so how do they do it? | [
"\"Eat through\" is a misnomer. Nothing is destroyed. Just changed. Acids chemically change materials into weaker substances. Take steel (iron) and HCl (arguably not the best acid for this, but it's easy). The reaction alters the metallic iron to iron chloride (ferrous chloride, FeCl2). Unlike hard, metallic iron, ... | [
"Yeah. In various ways. For example, the proteins in your body need a specific pH range to properly function. Acid changes that and denatures proteins, rendering them nonfunctional. Many acids are also strong oxidizers, like sulfuric or nitric acid, so you also get oxidation damage. Others are outright toxic, so yo... | [
"Ah, ok, that makes sense. So say you get an acid on your hand. The reason it is harming you is because it's essentially reacting with you?"
] |
[
"Where exactly does the heat from fusion reactions come from?"
] | [
false
] | null | [
"The fission and fusion reactions used for power generation and bombs are exothermic. "
] | [
"Yes, that much I know. But what creates this heat when the elements fuse? Like electrons, breaking of some force, etc? For fission it is clearly stated because of the release of high energy photons in the form of gamma radiation. Does fusion release photons or something else?"
] | [
"Most of the energy released by exothermic fission reactions is not in the form of gamma rays. And anyway even if that were the case, that doesn’t mean that the gamma rays are what cause the reaction to release energy.",
"You have the cause and effect backwards. The reaction is exothermic because it has a positiv... |
[
"How moving parts are lubricated in curiosity rover on Mars over these years? If not what technology is used to ensure longer life?"
] | [
false
] | null | [
"Finally my time to shine! (ME, been doing my PhD and been working ever since in aerospace tribology)",
"As was said earlier, lubrication is a BIG issue in space as similar metals will cold well if pressured into contact as soon as any existing coating (oil/grease, chrome protective layer, etc.) is removed. ",
... | [
"With opportunity and spirit they main missions was only planned for 90 martian solar days. Spirit's missions were extended until from 2004 to 2010 and opportunity kept going until 2018. In 2009 spirit got stuck in the sand so the retasked to station science platform. Opportunity's right front wheel drew more curre... | [
"Certain materials such as nylon and composite-impregnated metals are self-lubricating, so they don't require the direct application of a separate lubricant to function smoothly. Not sure if any of the Mars rovers actually use self lubricating components but that's my guess"
] |
[
"Can you trap a mosquito by flexing the muscle it's drinking from?"
] | [
false
] | A friend of mine said that if you were to wait until the mosquito is drawing blood and you clench your muscle then the mosquitos proboscis (sic) wouldn't be able to retract and that you could make it die from too much blood. I was skeptical, but I don't know insects so... what have you guys got for me? | [
"Short answer: It's unlikely.",
"Longer answer: If you look at a ",
"mosquito's proboscis",
", it's essentially a very thin, sheathed needle; it lacks the barbs or spurs you might see in other types of blood-feeding arthropods (ticks, for instance). Given this construct, you would have to apply quite a bit of... | [
"Unless you have video, the sidebar says:",
"Personal anecdotes and layman answers are not acceptable posts."
] | [
"Former Winnipeger here. Here's what actually happens: If you let the mosquito bite you and just watch it, it will use its legs to extract its proboscis and fly away. If you try to trap it by flexing a muscle or pinching the skin around it or whatever, the mosquito will do the exact same thing except it will flap i... |
[
"Would the accretion disc produced by two neutron stars merging into a black hole be composed entirely of neutrons?"
] | [
false
] | [deleted] | [
"Not entirely - neutron stars aren't ",
" neutrons, and may have a \"crust\" that contains some protons & electrons too. When you're ripping them apart, they're going to go through some interesting nuclear reactions and some of the neutrons will turn into a proton plus electron through a process called beta decay... | [
"To elaborate - free neutrons have a half-life of about 10 minutes, decaying to a proton, electron and electron neutrino (and occasionally an additional gamma ray). Once the neutrons are released from the intense pressures at the core of the neutron star, they will tend to undergo this process, and after a very sho... | [
"In general, the matter in the accretion disk will be too hot to form into atoms. The protons and neutrons should pair up into the occasional deuterium or tritium nucleus, though. This should be more common than in the early Universe, as there is a higher density of unbound neutrons (initially) relative to protons.... |
[
"How do elevators (and elevator banks) figure out which floor to go to?"
] | [
false
] | Multiple people on various floors, up, down... How does an elevator system keep wait times to a minimum? | [
"I actually had an interview question once about how you would model an elevator. The interviewer wanted to know what classes to create, the functions in the classes, and how the elevator would determine what floor to go to. ",
"The simplest ",
"elevator algorithm",
" is just for the elevator to continue movi... | [
"It's an interesting problem and there is no optimal solution (because there is no single parameter that everyone agrees should be optimized). Here is a story of someone who designs elevator algorithms: ",
"http://online.wsj.com/article/SB10001424127887324469304578143200385871618.html"
] | [
"Thank you. I imagine a crude parameter to be average wait time. A more sophisticated metric could be money generated by rent, which would be a bear to analyze."
] |
[
"In the honor of the upcoming mole day, is it possible to calculate the molar mass of an avocado?"
] | [
false
] | null | [
"A very simple approximation. ",
"12 grams of a sample of carbon-12 isotope contains one mole of substances as defined by Avogadro's constant. The mass of the avocado in grams divided by 12 gives us a ratio value, giving us the number of moles.",
"The ratio of the mass of the avocado to the amounts of substance... | [
"That wouldn't be correct though; An avocado is not 100% carbon. Is it possible to find the ratios of the elements that comprise the avocado and then use the molar mass of those elements to find the average molar mass of an average avocado. Yes, dehydrating the fruit would be a great place to start, but there are s... | [
"Sure, that would be quite easy. How much does an avocado weigh, something like 100 grams? Multiply that with Avogadro's number, 6.02*10",
" and you'll get the molar mass of avocados. This puts us at right around 1% of ",
"the weight of the Earth",
"."
] |
[
"Do we know how pangea formed or why it broke up?"
] | [
false
] | [deleted] | [
"Plate tectonics.",
" Pangea is the most recent supercontinent but it isn't the first.",
"The Earth is still molten in the interior, there's only a very (relatively speaking) thin layer of solid rock \"floating\" on the liquid mantle.",
"The layer of solid is fragmented into different plates and these are co... | [
"http://en.wikipedia.org/wiki/List_of_supercontinents",
"Rodinia and the older ones had no life, and were just barren rock surrounded by ocean. ",
"http://upload.wikimedia.org/wikipedia/commons/2/27/Oceanic_spreading.svg",
"Plates form as the surface cools, and the picture above shows how mantle convection so... | [
"http://en.wikipedia.org/wiki/List_of_supercontinents",
"Rodinia and the older ones had no life, and were just barren rock surrounded by ocean. ",
"http://upload.wikimedia.org/wikipedia/commons/2/27/Oceanic_spreading.svg",
"Plates form as the surface cools, and the picture above shows how mantle convection so... |
[
"Can dark matter form planet like objects?"
] | [
false
] | From my understanding dark matter is a substance that we think must exist because the way galaxies behave doesn't make sense without a lot of extra mass out there. Assuming I have that more or less correct, does the behavior only work if the mass dark matter represents is spread thin throughout space, or is it possible that dark matter may have come together from its own gravity into planets or planet like structures and still explain the movement of the galaxies? Edit: Thank you everyone for your answers, I have learned more about dark matter today than I have in my entire life. :) | [
"So you're actually asking a two part question:",
"Can Dark matter collapse from its own self-gravity into planet-sized bodies?",
"Could a lot of planet-sized bodies produce the same gravitational effects on galactic scales for which we believe dark matter is responsible?",
"To answer the second question firs... | [
"Yeah, there is something supremely psychologically dissatisfying about proposing the existence of an invisible 90% of the the universe's mass to explain the 10% you can actually see.",
"I actually used to side with you on this. Gravity is not well-understood - as of yet, we have never directly observed gravitati... | [
"I'm sorry if it isn't appropriate to add on a question that isn't exactly related, but there is something that has always bothered me about dark matter and you sound like you might be able to help.",
"Basically we assume dark matter must exist because galaxies spin faster than the visible mass would lead us to b... |
[
"As an enthusiast of astrophysics, and one who is out of the loop, I would love to know about quantum fluctuations."
] | [
false
] | Let's keep this in laymen's terms, but I can follow along pretty easily if it is explained with detail. I would love to know the math behind the big bang theory. I have watched a few lectures on how quantum fluctuations of energy can build up and potentially cause such an event, but how do these occur, and what is their natural starting phase. | [
"How do you know you have a \"true\" vacuum? You measure the energy of a region. But uncertainty in energy measurement forms a Heisenberg pair with uncertainty in time measurement. So if you want, you can kind of think about quantum fluctuations as imprecision in knowledge of energy over very small time scales. You... | [
" states have ground states. In principle, a free particle has no such restriction. A massive particle in its rest frame has no kinetic energy. "
] | [
"well we are pretty sure that space doesn't have edges, and even if it did, then we'd have to understand the physics of the edge of the universe to be sure (one of the reasons why we don't posit the existence of an edge). In reality, sure. Almost everything is a bound particle, even if the binding is exceedingly s... |
[
"When in evolutionary history did private parts become private?"
] | [
false
] | null | [
"This isn't an evolutionary matter, its a cultural one. There are societies right now where people do not share western values of modesty.",
"EDIT: Point of clarification, I am not claiming that modesty is unique to Western society. Quite the opposite, the great spectrum of beliefs surrounding the concept of m... | [
"Sexual modesty",
" has been observed in every human culture on Earth. That is quite a hefty coincidence to have nothing to do with either evolution or the widespread (in Western and non-Western cultures) practice of covering external sex characteristics.",
"None of us are any closer to actually answering OP's... | [
"Yes. Culture, not evolution: Anthropologists to the front!"
] |
[
"How lethal is acute radiation sickness today, compared to 1986 ? Has anything changed?"
] | [
false
] | Yeah yeah I'm watching the HBO show about the Chernobyl disaster. It made me wonder how ARS could affect us today compared to Chernobyl. Has there been any advances in medicine which could help mitigate the symptoms of ARS, and thus increasing survaivability? Are there better methods to treat patients today? I know the symptoms vary depending on the dose, but in general terms, has anything changed? | [
"There are basicly three things you can do for someone who has been severly exposed:",
"Decontaminate. Externally through the removal of clothes and washing the patient. Internally through some drugs that bind heavy metals like plutonium and allow them to be excreted and giving the patient potassium iodine so the... | [
"Filgrastim (recombinant G-CSF) was FDA approved in 1991, so it should have been in clinical trials or available experimentally in 1986, although I don't know when the idea to use it for radiation sickness was conceived, over 15 years ago I believe but I don't know exactly."
] | [
"FYI Chernobyl was in the 80s, not 50s. Are protein treatments newer than that?"
] |
[
"Can children or adolescents develop Alzheimer's ??"
] | [
false
] | My old neighbour texted me to catch up, he's a lot younger (15 or 16 years old) but then he said he was diagnosed with alzheimers since moving back to germany. I tried googling it but cant seem to find any legit cases of children with alzheimers.. does anyone have any input? | [
"If he has a family history, he might have gotten a genetic test. Mutations in the PSEN1, PSEN2 and APP genes predispose for early onset Alzheimer's. But even the early onset inheritable form generally only presents with symptoms in the 30s to 40s."
] | [
"it's possible, though \"unlikely\" (rare). there are genes (mutations) that predispose people to have early onset Alzheimer's (hereditary) but most cases affected folks in their 30's to 40's. the earliest/youngest known patient with dementia (Alzheimer's) is 23 at the moment"
] | [
"Not that I know of, specifically. I'm not an Alzheimer's guy, I just worked with prions and read up occasionally on other aggregation diseases. Plaque formation might be a stochastic process that takes its time until it really can take off. It id similar to inherited prion diseased - they also strike in the middle... |
[
"What would happen if a window from an airplane would break at high altitude during mid-flight?"
] | [
false
] | Let's say the airplane is going approximately 1000 km/h. At an altitude of 10 km above the ground. What would happen in the airplane if a window suddenly for some reason broke? Would people freeze due to the low temperature for example? Or would people actually get sucked outside or something? | [
"See ",
"this British Airways incident",
"."
] | [
"what a great thread to read as im sitting at DFW on a layover"
] | [
"D:",
"Note: that was the FRONT window, and it was fitted wrong. But still, D:"
] |
[
"Why are we not looking for life on Venus?"
] | [
false
] | I think the notion of "it's too hot for anything to survive" I was taught in school no longer applies since the discovery of extremophiles. I know it's a hard place to explore, but is that the only reason we're not doing it, or is there some other reason to believe there's nothing there? | [
"I was taught in school no longer applies since the discovery of extremophiles.",
"Thermophiles have been found in the range of 70C to 120C. The surface temperature of Venus is 460C. Venus isn't just hot, it's hot enough to melt lead.",
"In addition to being hot, it's dry. There's no water, ammonia or anything ... | [
"Venus missions",
"\n",
"from the Planetary Society",
"\nand to update where it lets off ",
"AKATSUKI (PLANET-C) The AKATSUKI is expected to usher in a new era of Venusian exploration. It was launched aboard an H-IIA Launch Vehicle No. 17 in May 2010 (JST.) It smoothly flew and spurted out jets from its ... | [
"Venus isn't just too hostile for life, it's too hostile for our machines."
] |
[
"How does a fractal pattern camouflage on Jets work? I understand how Army camos work by blending with the environment but in an open space like the sky,how does it benefit by the use of such pattern? Example image inside."
] | [
false
] | null | [
"1: This isn't a common pattern of camouflage and may be experimental- in other words it might not work that well.",
"2: In general, the blocky/pixely/fractal patterns on many new camouflage designs works by breaking up straight lines as much as possible. If you aren't really close, like in that picture, the huma... | [
"What you're seeing here is not standard. Every year, NATO hosts a training mission, called tiger meet. Each year, countries paint one of their jets as with a \"tiger\" theme. This may incorporate stripe, fangs, claws or other items. This seems to be a tiger meet flagship. ",
"Here is another, more obvious jet:\n... | [
"I'm not sure about this camouflage, but on concept cars put to production for extended road testing they will often wrap the car in a similar pattern to keep anyone who sees it from being able to clearly identify body lines. Volkswagen is one manufacturer I can think of that does this routinely. "
] |
[
"How is it that you can get energy both by splitting atoms (fission) and combining atoms (fusion)?"
] | [
false
] | [deleted] | [
"In fusion, the binding of two light nuclei, such as Hydrogen, forms a heavier nucleus, which has less mass than the sum of the hydrogen nuclei by themselves. This difference in mass is due to the different binding energies present in the nuclei. ",
"However, if you use two heavy nuclei, such as iron, the resulta... | [
"Look into ",
"liquid drop model of the nucleus",
", which describes why fission/fusion happens. I also posted significantly about stability of nuclei yesterday in askscience in the thread on ",
"the instability of Be-8",
". ",
"Oversimplifying a little (see above link), there's two counteracting forces... | [
"The ",
"silicon burning",
" Wikipedia article actually has a very nice, simple explanation:",
"At the end of the day-long silicon-burning sequence, the star can no longer release energy via nuclear fusion because a nucleus with 56 nucleons has the lowest mass per nucleon (proton and neutron) of all the eleme... |
[
"Can some things burn without oxygen? If so, how?"
] | [
false
] | Saw something in askreddit that said it can happen. With oxygen being part of the "fire triangle" I always thought it was impossible to burn anything without there being oxygen involved. | [
"One of the more commonplace fires that doesn't use oxygen (O2), are metal fires. Some metals, such as magnesium, will burn when heated in the presence of ",
"carbon dioxide",
", which is why a lot of welders will have specific ",
"fire extinguishers",
" at their job site than the common CO2 extinguishers."... | [
"Yes things can burn without oxygen. You just need a very strong oxidizer. Fluorine or chlorine trifluoride and two very strong oxidizers and they will react very readily and a flame will be produced.",
"https://www.youtube.com/watch?v=vtWp45Eewtw",
"http://en.wikipedia.org/wiki/Chlorine_trifluoride"
] | [
"Oxygen is merely the most common oxidizer, but it's not the only one. ",
"Related: the reason why lithium batteries are dangerous is that lithium fires do not require oxygen, and so once a lithium fire starts (for example, by overheating, overcharging, puncturing, or shorting out a lithium battery), it can susta... |
[
"How does Shazam and other apps like Shazam work?"
] | [
false
] | Even when there is plenty of background noise Shazam can still find the song. I was just curious on how these apps work | [
"The algorithm on how shazam works was published back in 2003. ",
"You can find it here",
". Of course shazam doesn't simply record music that you listen to and compare it with songs from it's database. Instead shazam doesn't simply have every single song in it's entirety in it's database but rather it generate... | [
"Shazam built the fingerprints themselves. Probably from a number of different sources- ",
"according to this, they got a large number of songs by digitizing Entertainment UK's collection",
". When Shazam launched with the App Store, they included tons of links to the iTunes store, so maybe they got a deal th... | [
"And how is this database made? Is it a copy of some existing database on the internet or it was made for Shazam and similar apps?"
] |
[
"are we really overpopulated/moving towards overpopulation?"
] | [
false
] | I keep hearing Internet misanthropes decrying overpopulation, and sometimes arguing for eugenic solutions to that, but is the view that our world is overpopulated by humans based on reality? | [
"What you're asking is a difficult question to answer, it depends a lot of future growth rates, increases in longevity, distribution of resources, and future undiscovered technologies. But you can get some hard facts from numbers, and since this is askscience, and you want some data, let's get some. I'm going to ... | [
"hydroponic agriculture falls under future technologies. ",
"As for what you can conclude, all I've given are raw quantities, and a zeroth order estimate. I'm not going to draw conclusions from them. As I said in the first paragraph, there are a ",
" of factors that can skew things by large margins.",
"For... | [
"but hasn't Malthus been completely discredited? in the end, technological progress and production ISN'T linear"
] |
[
"If light is massless, how is a black hole able to prevent it from escaping?"
] | [
false
] | null | [
"Light is massless, but it is affected by gravity.",
"Two ways to understand this:",
"Light has energy, and gravity acts on energy.",
"OR",
"Gravity is the curvature of spacetime, and so the paths that light can travel are determined by gravitational effects."
] | [
"I know the model, but a new question just popped up for me. ",
"Gravity is the curvature of spacetime, so the photon, for it's own point of reference, it's travelling through spacetime in a straight line. If it keeps going in a straight line, but the curvature of spacetime is directing it into a black hole, we m... | [
"Gravity is the curvature of spacetime. Spacetime becomes curved, or warped, by the presence of mass. The more mass, the more warping, which means stronger gravitational attraction. "
] |
[
"If we received a photograph from a random place in the universe, could we tell where it was from by looking at the stars?"
] | [
false
] | Hi AskScience, I was wondering this: if we received a photograph from a random place in the universe, could we analyze the stars in the photo and determine roughly where it was taken? We can assume the photo is clear and we have a good look at the stars and their relative brightness. The photo is just a simple RGB photo like . There is no crazy deep spectrum data or whatever else our super-powerful satellites use to look into the furthest reaches of space. I think this would be hard because the star field would look completely different to us from a random perspective. Additionally, the brightness of the stars would also be different. Would it require an impossible amount of calculation to determine where the photo was taken from? BONUS QUESTION: What if we took two photographs, with the camera being rotated 45 degrees between each photo? Would that make it easier? | [
"No, because the vast, vast majority of such images would have no discernible stars in them at all. ",
"There are stars in our sky but that is because we are embedded in the disk of a galaxy. A random place in the ",
" is overwhelmingly likely to not be in a galaxy at all. ",
"And even if it were, we do not m... | [
"I think this would be hard because the star field would look completely different to us from a random perspective. Additionally, the brightness of the stars would also be different.",
"In a static Universe, you could have a perfect cartography, at even the most insane levels of zoom. A gigantic computer may eve... | [
"Then, supposing you had all the IRAF star catalogs and a lot of time, patience, and puzzle-solving ability, you might be able to locate yourself if you were within the Sun's quadrant of the disk. You might get incredibly lucky and recognize a nebula. You also might by chance have captured one (or if yore incredibl... |
[
"Why do most medicinal pills have \"-HCl\" added to the end?"
] | [
false
] | null | [
"This means the medicine is formulated as the hydrochloride salt. Many drugs are organic amines, which would otherwise be basic, so neutralizing them with hydrochloric acid to form the corresponding salt is part of formulating them into a neutral form patients can take. This also makes them more water soluble for... | [
"It depends on the specific chemical and how strongly basic it is: it could irritate your throat on the way down, and not being as water soluble as the salt, it might not wash down off the throat lining as well, either. In addition, a lot of ",
"alkaloids",
" (morphine, quinine, etc) tend to be bitter as the ... | [
"What would happen if one were to take the non hydrochloride form? When you say basic, you mean they will hurt our insides?"
] |
[
"Is there an equation for how much water expands when turning from liquid to solid?"
] | [
false
] | null | [
"Yes, to be more precise, there is a property of water and ice that will tell you how much the water will expand. It's called ",
" and it's defined as the mass of the material per unit of volume. So a unit of density is the gram per cubic centimetre (g/cm",
" ). Water has a density of 1 g/cm",
" and ice has a... | [
"Crystals and amorphous solids exhibit varying density depending on temperature, hence thermal expansion."
] | [
"While density can be used to determine the volume change in a material, that's kind of the back door approach. There are entire tables of a material property called an expansion coefficient. It's a typically linear value that can be used in a formula to determine the volume of an object at any given temperature. I... |
[
"Is there a limit on the amount of things that a brain can retain?"
] | [
false
] | null | [
"There's a physical limit a to how much information can be stored in a certain volume. This has been asked before and I think the number I calculated was around 10",
" bits for the size of the brain. The actual number is certainly much smaller, but at least it's an upper bound"
] | [
"That's if you consider the brain to be similar to a computer's hard drive. It isn't so the comparison is not very valid. In \"The Shallows: What the Internet Is Doing to Our Brains\" by Nicholas Carr he argues that there's no actual limit of the brain's capacity to store memories but only in recalling those said... | [
"No, I consider it bound by the laws of physics. "
] |
[
"Why don't humans ever have yellow eyes?"
] | [
false
] | null | [
"\"there are many types of birds, Homo Sapiens is just one\"",
"Just clarifying meaning/intent, since this makes it sound like you're saying humans are birds- I think your intention is to say that Homo Sapiens is a single species whilst \"birds\" are an entire (class? subclass?) so there's a wider variety there. ... | [
"As far as I know, ",
" land vertebrates are unable to produce colors other than brown, black, or red through the use of pigments. Most bright colors are produced by refracting light."
] | [
"As far as I know, ",
" land vertebrates are unable to produce colors other than brown, black, or red through the use of pigments. Most bright colors are produced by refracting light."
] |
[
"Why is it that I suddenly get a ringing in my ears when staying sitting down?"
] | [
false
] | null | [
"Medical advice would violate the ToS of reddit.",
"If you were wondering what could cause occasional ringing in the ears, a potential answer could be ",
"tinnitus",
". However, I'm sure there are other possibilities."
] | [
"Tinnitus is not a cause, just the fancy name for \"ringing in the ears\"."
] | [
"Yeah, the rules forbid this type of posting, and also forbid answering it!"
] |
[
"Do insects get old in a manner that mammals do?"
] | [
false
] | Losing their endurance, speed, durability, brainpower etc.? Or do they remain same during all of their life? | [
"Interesting question. Some species have no mouth parts in their adult versions. They just breed and die. On the other hand Queen termites can live for 30 years. It takes monarch butterflies 5 generations to migrate north each season but the fifth generation migrates all the way to Mexico in the fall and partwa... | [
"Honey bees wear out as they age both physically and in the pheromones they produce. Since they can not repair damaged parts the wear eventually adds up to limiting the bees lifespan.",
"Once worker emerge as adults they spend time progressing through various jobs in the hive slowly progressing to forager. Foragi... | [
"I have no idea for house flys but its likely similar to bees, wing damage and chemical issues with muscles powering them. Predation is also a large factor. ",
"Honey bee workers work themselves to death as described they continue to fly until they are physically not able to. Foraging an area 3 miles in circumfer... |
[
"If we had a telescope 100 light years away from earth would we be seeing into the past? (And follow on questions)"
] | [
false
] | [deleted] | [
"A telescope at 100 ly would indeed see light that departed the Earth 100 years ago.",
"While I haven't done the math, I'm going to assume that it would be impossible to achieve sufficient resolution to see individual people as mentioned in your followup question.",
"And if there was a way to bounce back light ... | [
"Gravitational lensing and space dust would be a huge barrier to that kind of resolution, also. In theory, with enough computing power, you could model that in, but we are talking about solutions far beyond what our current technology could even begin to grapple with."
] | [
"I'm not doing the math either, but I think in theory, you could resolve the image of a person standing on earth from 100 light years away, but the size of the telescope would have to be really big. Like a perfectly shaped mirror the size of a solar system kinda big. ",
"As for photon reflection, the properties o... |
[
"How can modern humans and Neanderthal be seperate species if they interred?"
] | [
false
] | I have always been told that one of the things that define the cut off to a new species is losing the ability to interpreted. Since we all carry Neanderthal DNA how are they considered seperate species? | [
"This is covered in ",
"Why can two different species sometimes hybridize and produce viable offspring? Shouldn't they be the same species?",
". Interbreeding between different species is not unusual; there are many unambiguous examples. Even horses and donkeys, the classic example of sterile hybrids, occasion... | [
"Interbreed, not interpret. Anyway, there is no one perfect definition of species because you may always have a continuum across which organisms that are different enough to be considered different species, yet can interbreed to produce fertile offspring. You have to draw the line somewhere, but if every sexually-r... | [
"A chimp's DNA is not 99.8% identical to a human's DNA, that is a misunderstanding of the research. There are considerable differences between the two genomes."
] |
[
"If symptoms of a virus (like a cold) are indicative of the body's fighting off the bug, then do medicines that suppress the symptoms prolong the illness?"
] | [
false
] | I've always been taught that a runny nose, a cough, sneezing etc are all different ways of the body expelling the virus, wouldn't something that stops all of those then make it harder for the body to fight the illness? | [
"Not a doctor, but I can specifically say that one of the most notable examples of the body behaving in the way the OP describes is the fever response.",
"Infectious bacterial bugs (like most living things) have a preferred temperature range that they like to live and reproduce at. Temperatures too far above or b... | [
"Not necessarily, it depends on what we're dealing with.",
"The body releases a lot of mediators when you're sick, chiefly histamines and cytokines if we want to be specific about the symptoms you're referring to. These alert the immune system, and draw more blood flow to the area where the fight is going down. ... | [
"Great answers above, upvoted both.",
"Noone mentioned a specific class of drugs - corticosteroids. Corticosteroids are drugs that purpously SUPPRESS your immune system. They are based on, and in fact include, a natural hormone your body makes, cortisone/cortisol. This hormone and the drugs based on it natural... |
[
"Saturated Fat: what are the facts?"
] | [
false
] | I keep hearing on reddit that saturated fat is fine, and okay for you. This statement is usually introduced with citations from "Gary Taubs". Just because nearly everyone on reddit states that saturated fat is fine, I cannot get myself to believe it. The following departments and professional organizations recommend to stay away from saturated fat, as much as possible: The USDA The World Health Organization the International College of Nutrition the United States Department of Health and Human Services the American Dietetic Association The American Heart Association The British National Health Service the Dietitions of Canada The American College of Physicians the Cleveland Clinic the American Academy of Family Physicians The scientific consensus is obviously in support of the theory that saturated fat is bad for your health. Could they possibly be wrong? Is there extraordinary evidence to show that saturated fat is "okay" for you? If so, why have these organizations saying otherwise? On reddit, if you say that saturated fat is bad for you, then you get downvoted. Reddit doesn't seem to be "science denying", so what gives? My Sources: - PDF - PDF | [
"I'm kind of tired/hungry right now but I'll try and get this down as quickly as possible and then edit in relevant stuff later.",
"Saturated fats are ",
". Saturated fats ",
" are bad for you (same as anything else). ",
"Some saturated fats (such as Medium Chain Triglycerides, found in high amounts in both... | [
"I get that, but sometimes there is no citations or they're very hard to find and often just 'common knowledge' among anyone who's ever read a physiology textbook or something to that effect. Sometimes they don't even ",
" because clinical trials have never been conducted or can't be conducted within reason. Look... | [
"Is there extraordinary evidence to show that saturated fat is \"okay\"\nfor you? ",
"AFAIK nobody claims that short-chain saturated fats are bad, and medium-chain saturated fats are not usually disparaged either, so I'll assume we're discussing long-chain saturated fats (C14+).",
"If you eat more protein or ca... |
[
"Does squeezing a plastic milk bottle after pouring some milk, to reduce the amount of air in the bottle, before putting the cap back on, keep it fresh longer?"
] | [
false
] | This is something I've done sometimes and I wondered if the amount of air in the bottle has a meaningful effect on the life of the milk. Type of bottle in case there is any confusion: I suppose what I'm asking is, whether a reduction in interaction with air slows down the process of lactose being converted into lactic acid? Or any other part of the process? | [
"Temperature and light have more of an effect on milk than air content. Store your milk as far away from the door as possible and try to keep it around 39 degrees f. Don’t let it sit out longer than it takes to pour or transport it. You want to keep the cap on tight so the milk doesn’t absorb other flavors in the f... | [
"onsider getting organic milk or specifically UHT",
"Organic and \"UHT\" are quite different things.",
"If where you live all organic milk is also UHT then that's really crap. That's not the case everywhere.",
"Organic milk won't last any longer than regular milk.",
"The Scientific American article is misle... | [
"onsider getting organic milk or specifically UHT",
"Organic and \"UHT\" are quite different things.",
"If where you live all organic milk is also UHT then that's really crap. That's not the case everywhere.",
"Organic milk won't last any longer than regular milk.",
"The Scientific American article is misle... |
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