title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why do we think black holes are infinitely dense?"
] | [
false
] | I've heard black holes explained as mass concentrated into a single point (a singularity), where the density is infinite. Could it be possible to have a black hole where density is high, but not infinite, such that its surface lies within its Schwarzschild radius. | [
"Why do we think black holes are infinitely dense?",
"Because there is no force we know of which can support matter beyond a certain density against gravitational collapse. But, we really have no idea whether black holes really ",
" infinitely dense or not. Most scientists expect they are not actually infinit... | [
"Different theories predict different things about black holes. General relativity predicts it collapses to a point, but string theories predict the formation of what is called a fuzzball;",
"There's a big difference between \"some string theorists predict\" and \"string theories predict.\" I'm not a string theor... | [
"Ooop. You're absolutely right -- thank you for correcting. I didn't realize my statement was worded so strongly; will correct!"
] |
[
"Would it be possible to attach food, O2, energy stores and rockets to the ISS and send it somewhere else to explore?"
] | [
false
] | [deleted] | [
"Maybe with really really slow acceleration, lest you snap off a section with too much torque. Or if you put the rockets at the points where sections meet up. But it's probably a horrible, horrible idea."
] | [
"Engineering aside, I honestly think they'd all go completely batshit crazy before they even got out of the solar system"
] | [
"Probably. I was even thinking Mars or moons of Jupiter or something."
] |
[
"Is Listerine's burning sensation indicative of actual cleaning, or is it just there to make you think \"Wow this must really be working\", when in fact the burning has no functional use?"
] | [
false
] | [deleted] | [
"The burning sensation is due to ethanol and other disinfectants that clean. However, in the past many companies have released mouthwashes that are just as effective as listerine but do not have the burning sensation. They all failed because people did not believe they worked as well. So, to answer your question...... | [
"When determining the effectiveness of mouthwash you have to specify what it is you are trying to accomplish. Anti-plaque, anti-gingivitis etc. ADA (American Dental Association) only accepts a few ingredients as they have clinical proof that they are effective. Listerine is one of them. They use ethanol to diss... | [
"What makes listerine effective is the same thing that makes it burn. It is not necessary for a mouthwash to burn to be effective. Listerine uses disinfectants that burn specifically so that people believe its effective."
] |
[
"What causes objects in space to spin/rotate at the first place?"
] | [
false
] | Like planets or stars? | [
"Let's say you have two stars far away from each other, initially travelling parallel to each other in opposite directions. When they start getting attracted to each other, they start moving inwards towards each other. Because they initially have tangential motion with respect to each other, they start spiralling/r... | [
"No, I mean how the star or the planet itself revolves. Not spin.. Sorry if my question was unclear."
] | [
"What do you mean? All the rotation is from the initial motion."
] |
[
"How would I find the percent composition of simple sugars in a fruit?"
] | [
false
] | null | [
"Have ",
" ever run a GC? What sample would you run it on? I don't understand your procedure. ",
"Also, most simple sugars ",
" between 100 and 300 C. Boiling them requires significantly higher temperatures, so I doubt even the oven is hot enough. Also, at such high temperatures you risk combustion of the sug... | [
"Using long fancy HPLC columns seems inefficient, expensive, and not very accurate for quantitatively determining relative composition. Even chiral affinity columns might be better.",
"Why would fractional solidification take forever? You boil off the water or any other volatile solvent; then heat the sugar mixtu... | [
"Its still called a column, so I don't get your question. By stick to the column I mean retention times are determined by the partition coefficient between the mobile and stationary phase. In the U.K. this is colloquially referred to as 'sticking to the column'.",
"Anyway after a brief look around it seems most m... |
[
"Is there a chance for a number to never be rolled in a random number generator if it is ran infinitely?"
] | [
false
] | I got into an argument with a friend of mine who is working for a random drop in a video game. He says that if he were to do the task that gives the drop infinitely he would eventually get it. I argued that since it is random and there is no pity timer that even if he rolled infinitely there is still a chance he would ... | [
"Any \"random number generator\" you're likely to find will really be a ",
"random number generator (PRNG). In other words, it generates numbers according to some pre-determined algorithm. But if it's a good PRNG, it will have been shown a priori to generate numbers which very closely resemble a truly random sequ... | [
"This answer is not quite right. Assuming that there is a fixed probability p of the item drop, you're right that the probability of it not dropping is 1-p and that after infinitely many tries, the probability of it not dropping can be thought of as lim (1-p)",
" = 0. It would be correct to say that we will ",
... | [
"Mathematically speaking, he is right. ",
"If the probability of the item dropping from of a given task (\"event\") is 0 < p < 1, then the probability of it ",
" dropping is (1 - p). The probability of it not dropping from doing the task twice is (1 - p)*(1 - p), or (1 - p)",
" and the probability of it not d... |
[
"Why have the engineers at NASA outfitted their new manned exploration vehicle with rubber tires?"
] | [
false
] | The MMSEV (Multi Mission Space Exploration Vehicle) built at the Johnson Space Center seems to have rubber tires. Knowing how pedantic one has to be when designing equipment meant to go to the outer reaches of our solar system since you can't exactly pull up at a repair shop once you're on Mars, I was wondering why the... | [
"I would be surprised if that's the actual design. The various rovers have used ",
"tires that don't require inflation",
" and as you noted the Apollo landers used a more robust design. ",
"Best guess: They didn't want to ruin very expensive custom tires taking it for a joyride in Earth's gravity on asphalt."... | [
"Yeah, I noticed the tires too, and this was my interpretation as well- they were a temporary modification for use in testing on earth. I'm sure the actual rover, when used on a foreign planetary body, would not have inflatable tires."
] | [
"This is a 1-G mock-up test vehicle, clearly everything is not exactly near flight readiness (In fact for the MMSEV they are still a bit away from building flight-like). There is hardware you just can't use with gravity. This vehicle is mostly for cabin design and testing an independent wheel suspension system. "
] |
[
"Is a hot sauce only going to be as hot as the spiciest ingredient?"
] | [
false
] | [deleted] | [
"Yes. The spiciness will only be determined by capsaicin concentration. But people also like the consistency and taste of their hot sauce. Different peppers have different tastes. So blending certain peppers together will taste better than just a jar of pure capsaicin."
] | [
"You will be diluting the ghost peppers though, so it would make it less spicy."
] | [
"You will be diluting the ghost peppers though, so it would make it less spicy."
] |
[
"What exactly is going on when a \"shiver goes down my spine\"?"
] | [
false
] | And how does it relate to stimuli? | [
"It is not. ",
"NOT TO BE CONFUSED WITH MUSIC BASED TINGLES/SHIVERS\nThose are called frisson and can be discussed in ",
"/r/frisson",
" ",
"Please go there if you want that \"epic\" feeling."
] | [
"They don't know for sure. Until then, explore this world:",
"/r/asmr"
] | [
"I don't know if that's the type of phenomenon OP is referring to. We need more details.",
"ASMR is described as a pleasurable tingling sensation, often in response to calming stimuli like soft music or whispering; whereas the phrase \"shiver going down your spine\" is commonly used to describe a state of extreme... |
[
"How do we know that two photons are quantumly entangled?"
] | [
false
] | [deleted] | [
"Because we entangled them. There's no way to check if two specific particles are entangled; we have to make them entangled."
] | [
"And how do we go about doing that?"
] | [
"It's quite likely that we entangled them ourselves in the first place, but that doesn't mean we couldn't check random pairs of particles for entanglement. Whether you entangled them or not: you can still always measure their correlations and see whether they are stronger than allowed classically."
] |
[
"Does the Indian government has a protocol in place in case the Sentinelese decide to contact the rest of the world?"
] | [
false
] | null | [
"Not the right sub. Perhaps try a politics or law or some other kind of sub."
] | [
"Would it not fall into anthopology? Pretty sure scientists would be the one helping the Sentinelese, not government officials."
] | [
"The way the question is phrased it seems to be asking about what a current government policy/protocol is. That is not a science question."
] |
[
"Are we more well-rested when we use alarm clocks to wake us, or when we don't use alarm clocks?"
] | [
false
] | Setting alarms allows us to consistently wake up around the same time and develop a stable circadian rhythm. However, alarms do seem to be an abrupt disruption of our sleep, which can't be good, right? Conversely, not setting an alarm allows us to wake up in the most natural and gradual way, but is perhaps not very pra... | [
"Alarm clocks disrupt sleep, and leave you more likely to feel tired. Using a clock to align (in circadian biology, we can it entrain) your natural rhythms can work, but if you're waking up to the alarm, you're not waking up with your biological clock. People are not infinitely flexible when it comes to sleep times... | [
"Your body has two main phases NREM and REM, both these phases takes approximately 1,5 hour together before they start new cycle. To get a really good sufficient sleep you should cycle these phases at least 5-6 times throughout the night. If you interrupt the cycle before it's done it has actually negative impact. ... | [
"Why do schools still insist on early times? Is it really that more natural for adults to wake up early? Do they not also have hardships?"
] |
[
"If microprocessor manufactures are able to get more transistors on a processor why do they make them smaller?"
] | [
false
] | I understand that power and efficiency are factors they have to consider but if you're looking for all out performance why not make the processor bigger so that you can fit more transistors/cores/memory etc on it to make it faster? | [
"three things: propagation time, power consumption and (to some extent) price.",
"The first is that the electrical signal only goes so fast, slightly less than that of the speed of light. This seems fast until you realize that in one clock cycle at 3GHz light only travels 10 centimeters. Chips are usually less th... | [
"The size of the transistor is connected to the electrical capacitance of it.",
"The smaller the less capacitance, and the higher frequency you can run it at without making it too hot."
] | [
"in addition to the points raised by other comments -- don't forget that not only do the number of candidate chips from a wafer go down, but the increase in area means a higher fraction of the possible chips will overlap a flaw in the crystal, driving yields even lower. That is on top of the problem that a smaller ... |
[
"Rubbing alcohol is often use to sanitize skin (after an injury/before an injection), but I have never seen someone use it to clean their counters or other non-porous surfaces — is there a reason rubbing alcohol is not used on such surfaces but non-alcohol-based spray cleaners are?"
] | [
false
] | Edit: Whoa! This is now my most highly upvoted post and it was humbly inspired by the fact that I cleaned a toilet seat with rubbing alcohol in a pinch. Haha. I am so grateful for all of your thoughtful answers. So many things you all have taught me that I had not considered before (and so much about the different envi... | [
"Alcohol used to be the antiseptic of choice for instruments and surfaces in healthcare settings. It remains so in some countries and settings. Alcohol was only replaced because it was ineffective against spores and some viruses."
] | [
"It’s also highly flammable and sometimes using it over a broad area or enclosed space is a major fire hazard."
] | [
"All the replies in here, and this is the first mention of the fact that alcohol is flammable. Probably a big reason it's not used for general household cleaning, ",
"unless you want to burn everything down. "
] |
[
"How is symmetry spontaneously broken in superconductors?"
] | [
false
] | I was reading about how spontaneous symmetry breaking occurs in superconductors and how Nambu proposed that by “breaking the symmetry” you give energy to break apart Cooper electron pairs resulting in giving them mass. I don’t really get how this occurs in superconductors. | [
"Without knowing your physics background this is difficult to answer, so let's take it one step at a time.",
"The symmetry which is broken is ",
". Usually, you cannot create or destroy electric charge. But a superconductor is a special state of matter, a ",
" of Cooper pairs. (Here condensate is in the sense... | [
"You may be confusing two things here: the breaking of the symmetry and the breaking up of a Cooper pair.",
"For the symmetry breaking, it is easier to look at charge-neutral superfluids (for instance Helium-4 below 2.17K). The condensation is the same: bosons can be put in or taken out of the condensate at will,... | [
"energy to separate the massless electrons from pairs into individual electrons, and this energy you have just put in can then be seen as mass",
"OP wrote:",
"energy to separate the massless electrons from pairs into individual electrons, and this energy you have just put in can then be seen as mass",
"So, i... |
[
"How fast does an earthquake propagate?"
] | [
false
] | null | [
"The propagation of an earthquake would be equal to the speed of sound in the earth, which depends on the density, the shear modulus, and the compressibility of the material that the waves are passing through. This will be MUCH faster than the speed of sound through air, and a fairly tough calculation. Someone el... | [
"Are you asking about the speed of the seismic waves generated by an earthquake or the speed at which the actual earthquake rupture (so displacement on the fault surface) propagates? ",
"As for the first option, the speed of the primary waves (P-waves) would be the speed of sound in whatever material through whic... | [
"Here",
" is a plot of the seismic wave structure of the Earth. These wave speeds give the velocity that both shear waves (think holding both ends of a rope and moving your hands up and down) and compressional waves (pushing an accordion in and out) will travel through the Earth."
] |
[
"Are there any alternate explanations for the cosmic microwave background?"
] | [
false
] | When we talk about the decoupling of radiation from matter ~300,000 years after the big bang, what is actually occurring? I know the universe becomes "transparent" to its own radiation but by what mechanism is this happening? I'm an A-level physics student if that's of any help but I'm fairly familiar with some basic q... | [
"To talk about your second question, when we look at the edge of the known universe we are seeing a wall of hot plasma. The light is horrible at permeating this plasma because these unbound particles can absorb a near continiuum of light as thermal energy. Thus they couple very well and little light can escape. ... | [
"When the universe is young, hot, and dense (i.e. before about 300,000 years after the big bang), the distribution of photon energies is high enough that protons and electrons can't bond to form stable hydrogen. Thus, the universe is filled with a plasma, where photons, protons, and electrons interact at high rate... | [
"When we talk about the decoupling of radiation from matter ~300,000 years after the big bang, what is actually occurring? ",
"We call it 'recombination.' It was when the universe had finally expanded enough to be cool enough that the (opaque) electron-proton plasma was able to 'freeze' into atomic matter. Basica... |
[
"How do I hear music in white noise?"
] | [
false
] | I sleep with the ceiling fan and a loud stand-up fan to keep my noisy neighbors from waking me up. But as I'm falling asleep, I sometimes hear a faint, unrecognizable song. It wakes me up and then I can't hear it anymore. Is there any cause for this? | [
"White noise contains thousands of different frequencies. Your mind can subconsciously focus on certain frequencies, sometimes making up what you perceive as tunes. Also, take a look at ",
"auditory hallucination",
". "
] | [
"This may sound nitpicky but I feel that is one of the tenets of this subreddit! What you are describing is not white noise. It is probably closer to pink or red noise (but more likely not \"noise\" at all. it's most likely more 'signal' than 'noise'). I only say this because if you start doing some personal resear... | [
"Audiology graduate student here: Our auditory systems are able to perceive pitch and loudness due to a transduction process inside our cochlea (basically the nerve for hearing). After the sound signal has been changed into an electrical signal (inside the cochlea) that can be perceived by our central auditory nerv... |
[
"Did any Predators regularly hunt our hominid ancestors?"
] | [
false
] | null | [
"Interesting discussion, however that is not true about Komodo Dragons, I recently found another discussion about it and here are a couple of links that describe it in detail. ",
"A quote from the article: \"But \"that whole bacteria stuff has been a scientific fairy tale,\" said Bryan Fry, a venom researcher at ... | [
"Homo floresiensis was a pygmy ancestor from Indonesia who were hunted by Komodo dragons. So not only are you half the size of humans today, but gigantic lizards tried to eat you.",
"http://humanorigins.si.edu/evidence/human-fossils/species/homo-floresiensis"
] | [
"Haast's Eagle",
"\nVarious felids",
"\nVarious hominids",
"\nVarious crocodilians",
"\nMegalania",
"\nThylacoleo",
"\nHyenas",
"\nVarious others",
"Of course, odds are that in most cases these weren't ",
" ancestors, but humanity as a whole has had many predators. "
] |
[
"Wouldn’t cemeteries contaminate ground water like landfills do with lechate?"
] | [
false
] | null | [
"Yes. A quick Google scholar search can reveal several articles detailing the different contaminants and the risks that they pose. Contaminants range from heavy metals and organic solvents used in embalming to antibiotic resistant parasites. The potential is there. Natural attenuation can take care of some concerns... | [
"This is why sealable vaults are used. Vaults also prevent the divots that occurs when a coffin collapses underground. Earthquake can unseal the vaults though. ",
"I recommend natural burial if it is available in your area. This allows normal deterioration of the human body in a containment field."
] | [
"Not true at all. Embalming chemicals are a major source of pollution."
] |
[
"What criteria are used to determine whether black hole is stationary or spinning, if black holes can't be observed?"
] | [
false
] | null | [
"We can \"observe\" a black hole's spin just as we can \"observe\" its gravity - by its effect on other things. I don't know if any black hole's angular momentum has been measured yet, but it would be expected to drag spacetime around with it (frame dragging) which would have an effect on how things orbit."
] | [
"Also like to add that it's expected that all black holes have some spin anyways. Pretty much because it would be extremely unlikely to have the black hole have exactly 0 angular momentum. Additionally any actively accreting black hole will have angular momentum imparted on it from the infalling material."
] | [
"Not just how objects orbit, but it's distortion of spacetime affects the red-/blue-shifting of light from the objects behind it. "
] |
[
"If it is common for moons to be tidally locked to their planets, why is the same not true of planets and their stars?"
] | [
false
] | null | [
"It's because the tidal stress on the planet from its star is generally smaller (the exception being the \"Hot Jupiters\" which ",
" in fact tidally locked). ",
"The tidal force depends on not only the strength of gravitational attraction, which is quite strong from planets/stars of course, but also on an addit... | [
"It's in a 3:2 spin/orbital resonance, so tidal forces are strongly at play, though it's not the same thing as being tidally locked. It's no accident that Mercury is the only planet in our solar system to be so strongly affected by tidal forces since it's the closest to the Sun. The eccentricity of the orbit is to ... | [
"Thank you, this was very helpful"
] |
[
"How can I measure the amount of arsenic in water?"
] | [
false
] | I'm trying to earn a small research grant for myself for the upcoming summer. My research idea is to measure arsenic levels in the water in and around a place called Rabbit Island. The island is in northern Michigan in Lake Superior. Long story short, there's lots of stamp sand, which contains arsenic, copper, and chro... | [
"http://www.watertechonline.com/drinking-water/article/the-challenge-measure-arsenic-in-drinking-water-0807",
"Check the method IDs. Google isn't hard to use."
] | [
"http://pac.iupac.org/publications/pac/pdf/1992/pdf/6404x0575.pdf",
"(Edited to put in the context of As determination as opposed to As containing compounds, which the paper is talking about)",
"... an ICP-AES detector offered the possibility of continuous\nmonitoring of arsenic. \n...",
"... an ICP spectrome... | [
"There's a book called Standard Methods for water and wastewater that is exactly for this purpose. Given that the book is several hundred dollars, I don't have a copy lying around. However, I can almost guarantee there are several available methods...probably colorimetric, mass spec, etc. Check with EPA to see what... |
[
"Would sticking a conductive piece of metal in a USB port such that it bridges all the contacts fry the computer?"
] | [
false
] | What would likely happen? Would the USB controller be fried? I'm curious. | [
"It shouldn't, no. Generally, shorting out a voltage supply is a bad idea. However, the USB standard requires that there be some sort of protective mechanism in place. This normally takes the form of a PTC device - sort of an automatically resetting fuse.",
"PTC stands for positive temperature coefficient. Whe... | [
"Great answer, thanks!"
] | [
"Bridging all contacts would not cause the power supply to fry the computer, however you would need to worry about your data pins. The data pins are the two in the center, and they're usually around 1V positive or negative. If the metal object we're shoving in there contacts the 5V+ and data pins it will blast 5V i... |
[
"How does gravity behave in the center of the earth(or any planet)?"
] | [
false
] | If somehow a straight hole was drilled from one side of the earth to the other and was sustained, how would gravity behave? I mean to say that if something(or someone) where to decend into the hole, and assuming the temperature in the center of the earth didn't kill/disintigrate it/them would it simply remain there? ... | [
"As the other replies state, there is 0 net gravity in the center of the Earth. But for the mathematically inclined, I can add the following:",
"To see how this works mathematically, first observe that any spherically symmetric body can be thought of as a bunch of infinitely thin shells, all nested within one ano... | [
"Or more simply skipping the math, just assume that for every point in the perfectly symmetric shell which exerts a force, there is another exactly opposite which exerts the same force in the opposite direction.",
"They play tug of war with each other, and the center doesn't move. Now imagine that every part has... | [
"Yep, the derivation is for fun :)"
] |
[
"What part of the brain enables us to predict someone's sexual orientation?"
] | [
false
] | null | [
"There is no such single part of the brain"
] | [
"The brains of homosexual men are in some ways more similar to those of women. See an earlier thread on this ",
"here",
" with a relevant link. ",
"There are differences in how certain parts of the brain may be active (i.e. the extent to which they respond) based on sexual orientation. The easiest example of ... | [
"The brains of homosexual men are in some ways more similar to those of women. See an earlier thread on this ",
"here",
" with a relevant link. ",
"There are differences in how certain parts of the brain may be active (i.e. the extent to which they respond) based on sexual orientation. The easiest example of ... |
[
"3 Super volcanoes have been active this year all recording >4 magnitude earthquakes already. How big of a deal is this?"
] | [
false
] | Anyway, I'm wondering how often do these volcanos show activity. The other 16 supervolcanoes this site is tracking have shown no activity recently. Anyway, I was just wondering to what degree this is a threat. As far as I can understand, Supervolcanoes are labeled that because an explosion from them can impact the enti... | [
"Hey, you're from my home city!",
"But yeah, magnitude 4 is nothing, in Wellington we get a few of those a year. It's just the standard background rumbling - in fact, I've heard that it may be a good thing to have lots of little earthquakes to release the pressure, so when the \"big one\" happens it's not quite s... | [
"Hey, you're from my home city!",
"But yeah, magnitude 4 is nothing, in Wellington we get a few of those a year. It's just the standard background rumbling - in fact, I've heard that it may be a good thing to have lots of little earthquakes to release the pressure, so when the \"big one\" happens it's not quite s... | [
"If that's so, then why do seismologists hit the \"volcano panic\" button when they sense lots of little tremors in and around a volcano? Volcanic eruptions can be predicted, these days, but not earthquakes. Is the eruption of a supervolcano an earthquake?"
] |
[
"Venus is currently visible in the night sky in the US. Why is it going from super shiny big dot to almost not visible at all within 15 seconds?"
] | [
false
] | null | [
"Hi dizguc thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the followin... | [
"Planetary Sci"
] | [
"‘Planetary Sci’"
] |
[
"Magnets: Energy from repelling poles?"
] | [
false
] | I'm new to all of this but I had an interesting thought. North and south poles attract each other, but north + north repels; is there an energy that could be harnessed by holding the magnets in place and running a coil between them? | [
"The short answer is no -- you can't get any more energy out of repelling magnetic poles than it costs to bring them together.",
"If you want an explanation of why your specific idea is wrong you'll need to explain it a bit better -- where does the coil go?"
] | [
"An analogy that may be applicable is lifting a weight up to the ceiling and hanging it on a hook, the work you put in lifting the weight up is just stored as potential energy. There is no energy to harness until you unhook the weight and let it drop. ",
"Pushing the magnets together (or reversing the poles and p... | [
"Layman here but I took a grad-level class on Electromagnetics last term and stayed at a Holiday Inn Express last night.",
"The work you put in pushing the magnets towards each other is just exchanged with the potential energy of the field, which means no energy is created or destroyed, just stored.",
"There is... |
[
"Besides H20, would any other liquid be suitable to bathe in?"
] | [
false
] | Bit of a weird question but I'm curious. Is water the only safe compound humans can use to rinse off? Is there any other compound that: isn't absorbed by the skin; can mix with soap, skin oil, and common skin contaminants; is liquid at comfortable temperatures; nontoxic when ingested in small amounts; won't harm the ey... | [
"Milk isn't the type of answer I'm looking for since it's mostly water anyway--same goes for buttermilk, juice, etc.",
"I thought about vegetable oils but it seems like those would just leave you really greasy. "
] | [
"Supposedly people used to sometimes bathe in milk, because they thought that it was good for them and to show that they were rich enough to do that. ",
"Egypt's Cleopatara and Poppaea Sabina, a wife of Roman emperor Nero, took milk baths to improve their skin.",
"http://www.bbc.co.uk/news/uk-scotland-highlands... | [
"They would pour the (often scented) olive oil over their body and meticulously scrape it off."
] |
[
"Is the phenomenon of mixing certain foods and getting sick from that specific mix real? Or is it just in peoples' heads?"
] | [
false
] | null | [
"This has been removed because seeking ",
"medical advice",
" on ",
"/r/AskScience",
" is against our guidelines.",
"Please see our ",
"FAQ."
] | [
"Wow. Asking if a combination of food can make someone sick is medical advice and not human biology? ",
"Maybe I worded the question poorly as I had been drinking a bit, but I don't think I was asking for medical advice. I was asking a true/false statement about how the body works. \"Can a combination of food... | [
"Well definitely read ",
"this post",
" before you do anything. If you want help trying to rephrase the question to fit ",
"/r/askscience",
" after reading that, then ",
"message the moderator team",
" and we'll be glad to help you out!"
] |
[
"Is there any peculiarity about the places a supercontinent splits (e.g. the Atlantic coastlines of Africa and South America) or is it just about the subterranean magma flow?"
] | [
false
] | null | [
"There are a couple of things that (potentially) contribute to where the rift system that breaks up a supercontinent will localize, but all of them will generally lead to the rift system initiating broadly in the center of the supercontinent and roughly coincident with where the supercontinent was joined together i... | [
"Do plates fuse during the formation of a supercontinent? Is there any transverse motion creating faults? Are there hot spot volcanoes in the continental interior?"
] | [
"Do plates fuse during the formation of a supercontinent?",
"Yes, this is generally what happens during continental collision, whether this is occurring as part of supercontinent assembly or more generally. A suture (as I linked to above) represents a former ocean basin and plate boundary that was consumed during... |
[
"air conditioner heat removal rate"
] | [
false
] | Does the heat removal rate of a given air conditioner (heat removed per hour) depend on the temperature difference (Tout - T in) ? | [
"Yes. If it's not removing any heat then there's no heat being put out of the back. (In actual fact, that's not strictly true - there will be some additional heat produced due to the inefficiency inherent in the machine). If you're cooling a room, that heat is going to be put out the back of the machine."
] | [
"followup. Since the energy required by the air conditioner to remove a given amount of heat depends on the outside temperature, at what outside temperature is the rating (Btu/ hour) measured?"
] | [
"It really depends on the OUTSIDE temperature. As orbitalpete said, the heat is released from the back. Specifically, an air conditioner has two parts. If you think of a whole-house unit, you have an inside and outside unit. The outside unit (condenser) releases heat. If it is cold outside it is much easier to ... |
[
"Do the powerball numbers 01-02-03-04-05 have the same odds showing up as any other combination?"
] | [
false
] | Would I be anymore lucky picking random numbers than I would be if I picked 5 numbers that are next to each other? | [
"Every combination is exactly likely as any other (assuming the numbers are truly selected at random).",
"We humans tend to assign special significance to numbers with recognizable patterns like that, but they are only special in our minds. Every combination is equally likely."
] | [
"You could use this \"special significance\" to your advantage. :-)\nYou'll be among fewer people who choose those numbers, so your percentage of the proceeds will be greater!"
] | [
"The odds are exactly the same as you want a specific sequence to happen and each ball has the same chances to be picked.",
"For example, if you play with a coin, the odds are exactly the same between TTTT, TTHT, HHHH, HTHT, and any other combinations of head and tail. Here when you draw a ball, you don't put it ... |
[
"Why did my eyes change color from the time i was a baby?"
] | [
false
] | [deleted] | [
"Think that's odd? My birth certificate says I'm A- but my red cross blood donation says I'm O+..."
] | [
"On a side note, I was born blonde, now my hair is brown....why!?"
] | [
"As stated ",
"by wikipedia",
" and ",
"its citation"
] |
[
"How can meteorites be pure iron/nickel?"
] | [
false
] | I can't understand how some iron/nickel meteorites are pretty much pure iron/nickel. How did so much of these two metals condense from a gas phase to become a meteorite, or several meteorites, or asteroids? Did they used to be the core of a planet? Are they the nuclear ash splash from a nova? I'm OK with gases cond... | [
"With some exceptions, most iron meteorites are thought to have come from the cores of asteroids. The reason why they are so enriched in iron and nickel is due to ",
"differentiation",
", where the molten iron sinks to the center of the planetary body, leaving behind silicate materials floating on top. Nickel i... | [
"Oh man are asteroids blown - up planets? Why did that never occur to me "
] | [
"Yeah one way I've sort of heard it explained in reverse is that we should actually expect to find huge asteroids that are more-or-less pure elemental stuff. So out there somewhere there's probably an asteroid of pure platinum, because long long ago some huge planet in its molten state had all the different molten... |
[
"If we lived on a planet orbiting a sun (with similar characteristics of our Earth and solar system) closer to the center of our galaxy, could the light coming from the gas cloud surrounding a black hole outshine the sun?"
] | [
false
] | By a black hole I meant the black hole at the center of The Milky Way. | [
"In our galaxy, the SMBH at the center isn't accretiing, so it is completely dark. In active galaxies the accretion disk (and surrounding associated gas) is incredibly bright. The luminosity of the sun is ~4x10",
" erg/s. A typical AGN might have a luminosity of ~10",
" erg/s. That is 11 orders of magnitude b... | [
"The consensus is that most/all do. I'll just quote the first sentence of a 2009 review article (Turner & Miller):",
"Measurements of gas and stellar kinematics have shown that most galaxies harbor a black hole at their center (Kormendy and Richstone 1995; Magorrian et al. 1998; Ferrarese and Merritt 2000)"
] | [
"sorry, off topic but, has it been confirmed that all galaxies have a super massive black hole at its center, or just most, or it's just random?"
] |
[
"What are the key differences between neural nets and hierarchical hidden markov models?"
] | [
false
] | null | [
"There is a great stack exchange answer for this question ",
"here",
".",
"For convenience I've pasted it below:",
"The thing that is hidden in a hidden markov model is the same as the thing that is hidden in a discrete mixture model so for clarity, forget about the hidden state's dynamics and stick with a ... | [
"I only have basic understanding of Graphical models, but one key difference is that HMMs are ",
"Generative",
" models, while Neural networks are ",
"Discriminative",
" models.",
"Perhaps other are more equipped to explain this in layman's terms."
] | [
"Could you elaborate on what you mean by non-linear connectionistic approach? I think I understand the linear probabilistic method of HHMM"
] |
[
"Humidity makes it seem hotter when it's hot outside and colder when it's cold outside. Is there a medium temperature? (If it's above some certain degree the humidity makes it feel warmer but if it's below it that temperature it feels colder?)"
] | [
false
] | I've always wondered this and never got an answer. Say for example it's 80 degrees and humid, it will feel warmer than 80 degrees. OK, what if it's 75? Does the humidity still make it feel warmer? If I keep moving down at what temperature does the humidity stop making it feel warmer and actually make it feel colder? As... | [
"Give this QA a read.. Very informative.. Here is a snip",
"In our training at Penn State, one of our professors declared that high humidity makes it seem colder when the temperature is below 53 degrees F and warmer when the temperature is above 53 degrees F. This makes sense if you extrapolate the heat index cha... | [
"That's great! Thank you"
] | [
"It's heavily dependent on the amount of wind and amount of humidity."
] |
[
"What proportion of total solar irradiance at sea level is within the UV spectrum ?"
] | [
false
] | I want to know what fraction of the average TSI 1361Wm is UV and what fraction reaches the ground. | [
"Do an estimate based on the image.",
"Your question is starting to sound more and more like homework help, which I am not willing to partake in."
] | [
"I think this image will answer your question.",
"Really, you are looking for information on the solar spectrum, which will detail the amount of power at each frequency/wavelength. The nice thing about the image I linked to you is that it shows both the top of the atmosphere and the sea-level amount."
] | [
"I was hoping for the integral of this between 200-380nm."
] |
[
"What happens when you are \"burned to death\""
] | [
false
] | What happen to the body when you are burned to death? Does your internal body temp. rise too high like a fever except faster? What stages does the body go through? | [
"The big thing is your lungs. The rest of your body is surprisingly resilient but when you inhale hot enough gas your lungs blister and you can't get oxygen."
] | [
"Ok thanks"
] | [
"Whats happening is a bunch of things. The heat from the fire is burning your skin causing huge amounts of pain enough to knock you out. It's burning by either denaturing proteins or using the fat reserves in your body as fuel. The smoke, fire and heat from the fire is also entering your lungs throat and esophagus ... |
[
"Is it really harder to learn new things as we get older, or are we just making excuse?"
] | [
false
] | Does the human capacity for learning slow as we age? I feel like I'm making a lot of excuses as to why I'm not learning new things, or retaining things like I use to. Am I just making excuses, or is it really harder for me to learn new things? | [
"My personal experience is that plenty of older people learn rapidly and thoroughly. But this isn't the place for anecdotes or speculation, so let's go to the literature.",
"First, language. This may be a special case, but it is one much discussed; we often hear that when it comes to learning a new language, youn... | [
"I dont have a scientific explanation",
"Opening like this will get you downvoted every time."
] | [
"As a Linguist, I would say there isn't enough cause to apply your citation about language to this particular question because it is extremely specific about what it means to say Adults learn certain aspects of language more quickly than children."
] |
[
"What nutrients, vitamins,etc. affect brain neuroplasticity the most?"
] | [
false
] | null | [
"So seratonin is the main decider for neuroplasticity to simplify it? What about Omega 3 and it's affects? That's another one I stumbled onto recently while researching this.",
"As for Seratonin, not exactly a nutrient, but what do you think about 5-HTP SAM-e effects? It's a pill that's really popular here in Ser... | [
"https://booksc.xyz/book/10659323/88340d"
] | [
"https://booksc.xyz/book/10659323/88340d"
] |
[
"Is it possible to estimate Earth's total carrying capacity for Human Life? If so, what is it?"
] | [
false
] | As there are now around 7billion Humans alive on the planet (or will be soon, if not already), I was wondering if it was possible to estimate earth's carrying capacity for Human life. By carrying capacity I mean how many humans can earth support until some form of Malthusian catastrophe occurs. Will we reach a definiti... | [
"The idea of carrying capacity is ",
"indefinitely** i.e. without degrading the environment at all*.",
"To get a real understanding of this subject I highly recommend you read a book called \"Overshoot\" by William R. Catton. Or at least look up the terms \"population overshoot,\" \"carrying capacity,\" and \"d... | [
"turn solar energy into food at a 10% efficiency rate, which is pretty optimistic",
"That's ",
" optimistic! Currently, plants utilize solar energy at a rate of less than one percent. Some man-made solar panels, I believe, can get rates of up to 30-40% efficiency; however, converting this to food energy will ... | [
"I'll do a more optimistic, future-oriented estimate.",
"The average human needs about 2000 kcal/day. That translates into about 10",
" J/day. Energy on Earth comes from two main sources: solar and heat from radioactive decay. We'll consider this solar energy first (10",
" J) because its supply is infinite an... |
[
"Why do we have our most nutritious meal at the end of the day, rather than at the beginning?"
] | [
false
] | In western society, most people have their most nutritious meal (and often the only warm food) at the end of the day, around 6pm. In other societies, such as in asia, it is often taken as lunch. But as far as I know there aren't any big populations that start of the day with a big, warm, meal. Why is this? Doesn't it m... | [
"But as far as I know there aren't any big populations that start of the day with a big, warm, meal. ",
"Full English Breakfast - staple of the UK working class.",
"http://www.bbc.co.uk/food/recipes/stressfreefullenglis_67721",
"http://www.jamieoliver.com/recipes/pork-recipes/the-full-english"
] | [
"In most Latin American countries, lunch is the large meal of the day "
] | [
"Cultural reasons only.",
"Cultural and social. This I will agree with. I have seen it change for numbers of reasons. It's hugely important in determining meal times.",
"It doesn't really matter when you eat, not on body composition anyway. Carbs are just stored as glycogen until needed",
"This I am not sure ... |
[
"Why do we refer to the aging of items in \"half life\", why not \"full life\" or the complete age of the item?"
] | [
false
] | For example, the half life of DNA is 521 years. Why don't we say the full life of DNA is 1,042 years? | [
"because in 1042 years, you'll still have 1/4 of the original sample left.",
"Moreover, suppose you want to describe something that changes at a rate proportional to how much of that stuff you have. I have 100 atoms of stuff, and each one of them has an equal probability to decay in some time x. So at first, with... | [
"Let's be a little more specific with words. ",
"We don't know when ",
" any one part of our sample will decay. Each part is an entirely random process. So each atom in a sample of atoms is an independent random process. So ",
" to describe it, is when any one atom has had a 50/50 chance of decaying over time... | [
"Different elements indeed have different decay rates because different atomic nuclei have different stabilities.",
"You don't have to use half life. You can use 1/4 life or 2/3 life if you want, but half life is simple and convenient"
] |
[
"How do the delta's in the Coordinate System which Leonard Susskind outlines at the start of his Cosmology lecture (up on Youtube) work?"
] | [
false
] | He says the physical distance between two lattice points on the cosmological grid is a(t) sqrt(delta x + delta y + delta z I can't really understand the delta's here. I get that they're not really physical distances, because they're supposed to scale with the movements of the galaxies so that they stay in the same poin... | [
"a(t) does not depend on location. So why would we associate the same number for distance between a pair of galaxies and another pair, regardless of what pair we choose?",
"The best analogy for what's going on that I can come up with is this: sqrt(delta x",
" + delta y",
" + delta z",
" ) tells you \"how ma... | [
"I think you're on the right track. Here's another possibly helpful analogy/example: You're measuring the distance across the surface between two points on a spherical balloon. You mark off three straight line segments of equal length that stretch straight between the two points. So you can declare that the distanc... | [
"Sure, you can let the units of delta be as big as you want. If we set a(t) to 1 for a moment so it drops out of the distance equation, all you're doing with that equation is measuring the diagonal of a cube in some grid of coordinates via the Pythagorean theorem. The length itself does not depend on coordinates, b... |
[
"If there were more black holes than visible stars in our universe, could their mass and gravity account for that of dark matter?"
] | [
false
] | null | [
"The idea that massive objects could comprise the dark matter has long been pursued. We know any such stuff, if it were formed from normal matter, had to form before the epoch of nucleosynthesis, which started when the universe was only seconds old. That's why there's been a lot of investigation into \"primordia... | [
"You've got it backwards"
] | [
"You've got it backwards"
] |
[
"How are desirable traits in Bonobos selected?"
] | [
false
] | From what I understand, they have indiscriminate sex with every bonobo of the opposite gender that they encounter. Wouldn't this eliminate natural selection for bonobos? | [
"Nope. It means that a bonobo that doesn't die early on and stays fertile will probably have more children than a dead bonobo.",
"This is enough for natural selection to work."
] | [
"Without any selection, the bonobo population would increase exponentially. It clearly isn't (in fact, they're endangered), so there's still selection occurring. ",
"So, you're asking, selection for what? As DoorsofPerceptron pointed out, there's selection for survival, which is not trivial. And there still is p... | [
"I kind of understand but I still feel like there's something I'm missing. Aren't all the bonobos alive rather a large selection of phenotypes? There seems to be a lot of variation in the gene pool, and it seems like any male member of a group of bonobos is equally as likely to impregnate, as opposed to the most su... |
[
"Is there a way to consciously control the exact moment when we fall asleep?"
] | [
false
] | Recently, ive been able to hold myself in a wierd limbo between sleep and being awake. It feels like im hallucinating but i can control the direction the images and voices take as well as will myself awake and back into hallucinating. The only drug ive tried is marijuana, not recently, but being really high was similar... | [
"This isn't science based but rather something I do to help myself fall asleep. Once I'm ready to fall asleep (I can't keep my eyes open while reading) I close my eyes and starting counting my breaths. When I lose count, I know I've slipped to a lower level of consciousness. By remembering the last number I was at ... | [
"and the weight in kg."
] | [
"If you ",
" were a robot, the distance would have been measured in cm."
] |
[
"Question about brain tumor, in particular Glioblastoma?"
] | [
false
] | I just came across an article about the treatment of Glioblastoma and was wondering a) why is it that a Glioblastoma is so severe and other braintumors are not, even though they can be huge in size as well and b) what do people suffering from a Glioblastoma actually die of (for example, does the tumor eventually causes... | [
"A) Glioblastoma is severe for a few reasons. First, it grows very quickly and has a tendency to appear \"out of nowhere\" already quite severe. Here's ",
"one month's growth",
", if you want to see an example. Second, it's hard to remove via surgery, since it can often have \"tendrils\" that are hard to find a... | [
"I can answer part a:",
"Glioblastoma cells are very ",
" and ",
", much more than the \"average\" cancer cell. The tumor cells move to other areas, so they physically spread around the brain. It only takes a few months for the cancer cells to spread and \"take over\" the brain.",
"Here's a ",
"review a... | [
"Thanks so much for your answers. Especially the second study seems quite on point to my second question. I‘ll have a closer look at it. Would it be okay if I come back to you with follow-up questions in case they arise? "
] |
[
"Why do humans die at body temperatures of 42°C, while the same temperature is normal for birds?"
] | [
false
] | [deleted] | [
"As you suggested, protein denaturation is the reason why humans become very unwell and eventually die with a core temp of 42ºC.",
"When it comes to protein stability and evolution, evolution typically does not select for stability, but rather function. So if being stable at 42ºC is required for function, evoluti... | [
"Surely their protein structure must be somehow superior to ours",
"Superiority can only really be judged in context. Humans typically inhabit an environment which allows them to efficiently radiate the heat from their bodies and maintain a contstant (low) body temperature irresepective of their level of physical... | [
"I have had a temp of 42c measured orally...very unwell does not describe the sensation well."
] |
[
"Is it more effective to hold a door shut using your upper body pressed against a door, or using the static friction of your shoe against the floor at the bottom of it?"
] | [
false
] | [deleted] | [
"(note that the following assumes a rigid door - we all know that the possibility of the door bending is real, but that's ignored here) ",
"In either case, it's all friction. When you press your upper body, you are still holding yourself in place using friction of your feet against the floor. To open the door... | [
"I'd think leaning against the door, since you're using your feet to hold the door in place either way (your torso doesn't hold itself against the door), but when leaning against the door, you can push against it to increase the normal force of your shoes against the floor, thus increasing the frictional force resi... | [
"At the expense of bringing your muscles and ability to maintain your balance in to the equation.",
"From experience we all know the shoe is more effective."
] |
[
"Why is the common decent model accepted and the multi-ancestor model not?"
] | [
false
] | [deleted] | [
"Basically, only because our models say it is more likely to have one root than multiple to the tree of life. Here's more info on the ",
"Last Universal Ancestor",
" if interested.",
"However, you could still be right for reasons that the models do not take into account."
] | [
"all extant organisms are just too similar to have multiple origins: we all store genetic information as DNA (except retroviruses but that's a whole different mess...), all use the same nucleotides in said DNA, all use the same combinations of nucleotides to code for the same amino acids, and all use remarkably sim... | [
"source says: A universal common ancestor is at least 10",
" times more probable than having multiple ancestors…",
"Well that's a big number."
] |
[
"Do/can we use lightning rods to gather electricity?"
] | [
false
] | null | [
"Ohm's Law won't help you here :P You're looking for P = I * V.",
"1.21 GW sounds a little on the low side (my low-end numbers would give you ",
"30 GW",
") but it's within the same ballpark. Back To The Future at least got the whole \"there's no way in hell to store it\" part right."
] | [
"I'm a mere EE student, so take this with a grain of salt.",
"I don't think there is such a system because a bolt of lightning is an extraordinary amount of power. My reference book says that an average bolt of lightning pushes a current of somewhere between 30,000 to 300,000 Amp at a respectable 1-100 MV, and t... | [
"You can safely assume any very tall structure will be struck regularly, skyscrapers in particular get hit quite often.",
"Belltowers aren't quite high enough to qualify, but should still be equipped with a lightning rod as a protective measure."
] |
[
"What are June bugs and moths doing when they attach themselves to my window screen for hours?"
] | [
false
] | Are they really just lazy or is there a purpose to their lounging? They sit there forever. | [
"No, ",
"June bugs",
" are beetles in the ",
" genus. Though Wikipedia lists other north american beetles often called \"June Beetles\". (Not being condescending, genuinely curious, but Why didn't you just google it?)"
] | [
"No, ",
"June bugs",
" are beetles in the ",
" genus. Though Wikipedia lists other north american beetles often called \"June Beetles\". (Not being condescending, genuinely curious, but Why didn't you just google it?)"
] | [
"I am also interested in this but would like to clarify that I am specifically interested in what they are doing when they have not been drawn to a light source. In my case they tend to aggregate to the side of the house facing south to southwest and with lights on or off. There tends to be larger moths like ",
"... |
[
"With Entangled Cooper Pairs, can you resolve the \"which way\" quantum dilemma issue with the Lorentz Force?"
] | [
false
] | null | [
"Entanglement doesn't allow FTL communication."
] | [
"It theoretically can? Hence the whole \"spooky action at a distance\" quote from Einstein.."
] | [
"The no-communication theorem shows that it can’t."
] |
[
"If the LHC is the only thing powerful enough to do the experiments it does, how can science verify its results?"
] | [
false
] | null | [
"Here is an answer I gave in another ",
"thread",
" a couple of months ago:",
"Certainly, while it would be nice if there were two accelerators in the world that could perform to the level the LHC is capable of, there actually is independent confirmation of the result, both at the LHC and, to some extent, fro... | [
"to simplify fishify's response, the LHC is an accelerator-collider, the \"engine\" that drives a number of different experiments stationed around it."
] | [
"I'd like to point out that Fermi-Lab's ",
"Tevatron",
" was also capable of detecting the Higgs, and published a result on its detection there just before closing in september.",
"Because the LHC is higher energy, the number of possible higgs events expected in a time period is higher. The Tevatron, with co... |
[
"To plant scientists: What are the most efficient plants to put inside a home for producing the most oxygen and cleaning up the air?"
] | [
false
] | [deleted] | [
"Back in the ‘80’s NASA studied exactly what you’re asking. ",
"You can find the quick chart here, or read the original study if you’d like. ",
"https://en.m.wikipedia.org/wiki/NASA_Clean_Air_Study"
] | [
"Depends on who you talk to everyone will have a different list to give you. Aloe vera is one that always seems to make the list. Mums and dracaena are also on most house plant lists.",
"If you are fairly new to house plants I suggest a spider plant to be your choice. Very easy to take care of, and it takes care ... | [
"Sounds good. I live in Vegas, anything I should get in particular to keep bugs and stuff away?"
] |
[
"How does donating plasma help save lives exactly?"
] | [
false
] | Please be as detailed as possible! | [
"Blood plasma can treat hypovolemia (not enough blood). Plasma you donate can be put straight into another person (provided that the blood types are compatible.",
"If the plasma is processed, compounds like clotting factors, and immunoglobulins. These can be used to treat diseases like hemophilia. "
] | [
"Plasma still has to be matched. ",
"Here's a chart"
] | [
"I always think it's important to differentiate between donating plasma and selling plasma. When I say selling plasma, I'm referring to the plasma centers where you are paid for your plasma. You can also donate plasma, when you donate blood for a blood center like the Red Cross, the whole blood is separated into pa... |
[
"Can a given function be expressed as another unique function? If so how does one find these overlaps?"
] | [
false
] | I was wondering since there is an infinite amount of functions possible, there must be certain intervals in completely different functions that are almost identical. For example, are there polynomials (in terms of x) that are identical/similar to ln(x), e , sin(x), cos (x), etc.? How are these found...by chance? By the... | [
"There are at least three answers to your question, depending on exactly what you are asking.",
"Fix some function f(x) on a closed interval [a,b]. If ",
" is continuous, then we can approximate ",
" arbitrarily close by a polynomial on that interval. This is actually a very strong statement since polynomials... | [
"You say there is no polynomial that is EQUAL to those \"analytic\" functions. What is the definition of equal?",
"The functions ",
" and ",
" are equal on a set ",
" if f(x) = g(x) for every ",
" in ",
".",
"For example is there a polynomial that is approximately those functions?",
"As I wrote, if ... | [
"Yes. The coefficients can be any real number. In general, a polynomial is of the form",
"a",
"x",
"+a",
"x",
"+...+a",
"x",
"+a",
"x+a",
"where a",
" are any real numbers. If a",
" is not 0, then we say that this polynomial has degree ",
" (the highest power of ",
" that appears)."
] |
[
"Why does table salt applied to a wound cause pain?"
] | [
false
] | I know that sodium is involved in a neurotransmission, but I'm not sure if that is related. I also know that NaCl is essentially pH neutral, so I don't believe any acid-base reactions are going on. | [
"A quick Google search turned up this answer",
"Provided by Walter Sipe, M.D., clinical fellow of pediatric gastroenterology, hepatology, and nutrition, University of California, San Francisco (former HHMI medical fellow)\nBefore we get to the science part of your question, let me start by saying: Do not put salt... | [
"It leeches fluid from the tissue surrounding the wound. Additionally, it may directly activate some pain receptors, but I can't find any support for that theory right now."
] | [
"Thanks for saying \"this answer\" rather than \"the answer\". The thing about sodium is that it has a critical function in generating the most basic part of the nervous response, the action potential. Any time you mess with sodium concentrations, you're affecting the function of neurons at a deep level, not just... |
[
"If the stratum corneum is dead and covered in bacteria, why doesn't it decay?"
] | [
false
] | null | [
"It does. It constantly does. Think of your skin like shark teeth. Always having a new layer to push the old, dead layer out. Constantly being replaced. "
] | [
"The stratified cells are tightly bound together, keratinized like fingernails, waterproof, and constantly shedding. The inhabiting bacteria lack enzymes to break down this cornified layer."
] | [
"The stratum corneum has a high turnover rate and is constantly shed to avoid bacterial invasion."
] |
[
"Can you get drunk by inhaling alcohol vapors?"
] | [
false
] | null | [
"The danger here is that you can not vomit unabsored alcohol to prevent further intoxication if it is overdone."
] | [
"The danger here is that you can not vomit unabsored alcohol to prevent further intoxication if it is overdone."
] | [
"Yes because the vomiting reflex in regards to over consumption of alcohol is due to the fluid in the semicircular sacs in your head by the ears (basically motion sickness). Fun fact: if you drink heavy water at a particular ratio to alcohol, you won’t feel dizzy and won’t vomit if you over consume. ",
"EDIT: ",
... |
[
"Is the Delta variant a result of COVID evolving against the vaccine or would we still have the Delta variant if we never created the vaccine?"
] | [
false
] | null | [
"Delta arose in India when vaccination levels there were extremely low. Delta has only slightly increased vaccine resistance relative to the earlier strains of SARS-CoV-2. And delta has greatly increased transmission capacity. ",
"So delta arose in the absence of vaccination, doesn’t do much to avoid immunization... | [
"I think there's a common misconception that needs to be addressed here- something that makes a lot of people believe that vaccines can cause mutations in viruses. Since antibiotics can cause resistant bacteria to evolve over time, it's easy to think that something similar can occur with viruses and vaccines. Howev... | [
"Excellent answer. One quibble: using the term 'attaching themselves'. \nI think it is better to say that the virus 'becomes attached'. ",
"I know this is a nuance, but I read variations of 'attaching themselves' a lot and it gives the impression that a virus is acting in some deliberate manner as though it was ... |
[
"Why could a pebble made of neutron star material slice right through the Earth?"
] | [
false
] | During episode 3 of Wonders of the Universe a couple of weeks ago, Brian Cox makes the statement that a pebble made of neutron star material would weigh more than Mt Everest and, if dropped, "it would slice straight through the Earth like a knife through butter." How could this happen? When a normal object is dropped,... | [
"The density of neutron star material is so high that even the ordinary force of gravity would create tremendous pressures if a small pebble were to rest on the Earth. The entire weight of Mt. Everest weighing on a spot only a square centimeter or so in area would generate pressures far in excess of those any ordin... | [
"presuming of course that it was at rest on the surface to start and the earth was a perfect sphere and whatnot. If perhaps it was the situation I imagined in my head when I first read OP's question, a pebble of neutron star flying in from space, it would accelerate down, cut through the earth, decelerate on the wa... | [
"ëh, figurë a nëutron's on thë ordër of 10",
" fm, and ëach has on thë ordër of 1 GëV of ënërgy. Thërë's 10",
" fm",
" in 1 cm",
" so 10",
" GëV of ënërgy? that's likë 10",
" Joulës which is thë samë as thë rotational ënërgy of thë ëarth's rotation says wiki (ordërs of magnitudë articlë, I can't link)"
... |
[
"How do T-cells know which cells they've already inspected?"
] | [
false
] | From what I understand, T-cells are constantly traveling in the body, inspecting cells by looking for antigens. If they're self antigens, then the T-cell doesn't attack, whereas if they're non-self, they attack. My question is how does a T-cell know when it just inspected a cell? Does the T-cell leave something behind ... | [
"It doesn't know. And it doesn't loop because it's not like the T-cell specifically waits until the current cell under investigation has \"passed inspection\" before moving on. The T-cell just moves around, continuously coming into contact with other cells in the neighboring environment, and if it happens to brus... | [
"It might help to see ",
"this video",
", to get a sense for the amount of movement even in a fairly calm environment, the lymph node. Once T cells dissociate from their scanned target, just the random jiggling about in the node means that it almost certainly will find a new target rather than just re-attachi... | [
"T-cells have long processes that they use for palpating/probing MHC (the cell-surface molecule that presents antigen). If they find a matching antigen they are activated, if not, they move on (diffusion or what-not).",
"Much of this probing/activation will happen in lymph nodes, where there's plenty of cells jos... |
[
"What's going on chemically when acid melts through stuff?"
] | [
false
] | Does it cause some sort of chemical reaction that destroys some chemical bonds or something? | [
"At low concentrations, H+ ions react with X (often a metal) to make H2 and X+. So hydrogen takes electrions from whatever is reacting with the acid. This produces hydrogen gas, and the the ion of the reactant. This reaction will still happen for most acids that become concentrated.",
"Some acids, when concent... | [
"Do you a particular example you have in mind?",
"One that I can think of is the reaction between hydrofluoric acid and glass (which is mostly silicon dioxide). This weak acid will eat through the glass no problem. It's used as an etchant.",
"The fluorine in the acid reacts with the silicon in the glass to prod... | [
"Yes, it does. Thanks!"
] |
[
"Why does gene damage & mutation eventually end up with cancerous cells but not with something else?"
] | [
false
] | For example why doesn't it end up with absurd but harmless features? Like, say, you have serious gene damage & mutation in the cells of your breast. Why do those cells become rapidly growing & reproducing cells, instead of, idk, growing weird red hairs on your breast? It might sound dumb and sci-fi but I hope you get t... | [
"Sometimes random mutation does result in such things! However, because the human body has an incredible amount of cells, a single mutation will rarely be very perceptible (especially because many cells are part of large systems that will compensate if it stops performing a certain function).",
"Single-cell mutat... | [
"it doesn't! you know how older people often have weird pigmentation spots on their skin? also skin tags, and hairs growing out of strange places and so on? that's exactly what you're describing",
"we have trillions of cells in our bodies, a lot of which continue to divide for the rest of your life. mutations hap... | [
"Also, in most cases, the genetic mutations initiate the cell’s “self destruct” mechanism, causing it to die."
] |
[
"Are the rings of Saturn really so fine or is it some due to lack of photographic resolution?"
] | [
false
] | In nearly all the photos of Saturn the rings show up as vivid and almost smooth in texture. Are the photos true to nature and the rings are made up of very fine/small rocks/debris? Or is this some kind of photo effect? Things in space are pretty dark so perhaps the exposure might have to be pretty long in order to take... | [
"Saturn rings are formed from ices and rocks ranging in size from millimeter to meters max (not so common) so in comparison to the huge Saturn, and since they are mostly in the same plane , they seem fine.",
"http://en.wikipedia.org/wiki/Rings_of_Saturn",
" "
] | [
"It's sort of like taking a picture of the beach - it's made of sand with some larger rocks mixed in, but from any distance (like an airplane to take the example closer to the relative distances of spacecraft from the rings) they all blend into a relatively smooth color."
] | [
"Exactly. It's worth remembering the scales involved here. Just the B-ring (the inner of the two brightest rings) is twice as wide as the diameter of the earth - with a maximum particle size of a few meters, it is even finer than sand on a beach."
] |
[
"If photons are massless, why are they affected by gravity?"
] | [
false
] | null | [
"Because - contrary to what your physics teacher may have taught you in high school - gravity isn't a mysterious force-at-a-distance proportional to the masses of the two objects. In other words, you don't need to have mass to feel gravity (or to gravitate yourself).",
"The picture of gravity you're thinking of i... | [
"Please please please look in ",
"r/sciencefaqs",
" before posting. You'll find ",
"the answer",
" there. A ",
"search",
" of previous questions yield ",
"many results",
" as well."
] | [
"Only massive objects create gravitational fields",
"This isn't true at all! Spacetime curves in response to both energy ",
" mass, and since massless particles like photons still have energy, they'll curve spacetime. As I mention in my top-level post, this isn't just a pedantic concern. Photons were ",
" dom... |
[
"What is actually happening when you whistle?"
] | [
false
] | null | [
"The air spaces either between your tongue and teeth or tongue and the roof of your mouth create a resonant chamber that vibrates when you blow air through it. You can change the size of the chamber by moving your mouth/tongue to create different pitches. ",
"edit: grammar"
] | [
"Usually the faster you get the air to pass over the resonant chamber the harder it vibrates and thus the louder the whistle gets. I believe using your fingers makes a more stable resonant chamber that you can blow harder on and thus produce a louder sound."
] | [
"Why does rolling my tongue over with my fingers allow me to whistle 50x as loud?"
] |
[
"If you wear less clothes than comfortable in the winter. Would you a) lose weight due to increased metabolism burning fat to keep warm, or b) trigger the body to go into hibernation mode and store fat?"
] | [
false
] | Just curious | [
"...humans dont hibernate.",
"You'd probably c) be cold, and d) eat more to make up for the extra energy youd need to stay warm."
] | [
"I typically lose weight in the winter and I by some people's terms don't ware enough layers. Also I will shovel snow in a pair of shorts and a t-shirt because I get really hot and feel like I'm over heating. But I prefer a colder climate any ways. So my story might not be any help to you. "
] | [
"I .. can't tell if you're trolling me"
] |
[
"Humans need oxygen, but what other gases can replace the other elements in air? More specifically can argon replace nitrogen and would it be safe to breathe?"
] | [
false
] | I was recently watching and in the episode it was mentioned that the planet's air is 20% oxygen and 80% argon (or something like that, it's not mentioned in wiki). I was curious about this and dug up about the exact same thing. Then I found . The argon section is lacking. Can we safely breathe an argon-based atmosphere... | [
"You can breathe it. It just doesn't offer significant advantages over nitrogen for regular uses. They use breathing gas mixes to avoid nitrogen narcosis at high pressures mainly. Argon doesn't improve upon nitrogen in this respect (it's actually 2x worse according to sources I found), so there's no reason to us... | [
"Semi-related"
] | [
"Actually, argon could be neuorprotective over nitrogen....",
"Here",
"It's important to add that I can find evidence that ",
"xenon",
" can be used as an anesthetic, so we can expect argon to have greater narcotic effects than nitrogen. This could be an issue if we're talking about %'s reflecting our atmos... |
[
"A question about Jupiter and the other gas giants?"
] | [
false
] | Are the planets just pure gas? Can I drive a spacecraft straight through the center or will I eventually hit something? What holds all the gas together in a planetary shape? | [
"Well, we know its size, and we know its gravity. What we actually don't know is it's composition. :) Not entirely. We have guesses and approximations, that are probably really, really close, but we don't know it ",
". And that's kind of the hold up. ",
"And, because of the extreme pressures, temperatures, and... | [
"/u/seek3r_red",
" has answered pretty well, I'd just like to share this link: ",
"http://en.wikipedia.org/wiki/Jupiter#Internal_structure",
"...and focus on this particular point:",
"Can I drive a spacecraft straight through the center or will I eventually hit something?",
"Definitely not. Even if there ... | [
"We only know its composition at the surface, because that's all we can see. We know its mass, but we don't know if there's a solid mass of rock and metal in the center or a mass of ice or the gas just gets progressively denser. Its average density is 1.33g/cm",
" but that doesn't really tell us anything about wh... |
[
"Question regarding light and how cameras/eyes see images"
] | [
false
] | [deleted] | [
"What do you mean by 'ordered fashion'?"
] | [
"I imagine that it wouldn't attain that configuration; I imagine light travelling in many directions and very chaotic so it doesn't make sense to me that we see images."
] | [
"I believe OP refers to",
"When you see a diagram of how a lens works, it shows light entering in parallel lines and then focused. ",
"and imagines that light coming in from objects somehow attains this configuration before entering the lens."
] |
[
"Chemical trails?"
] | [
false
] | null | [
"It's a common optical effect: it's the shadow of a thin straight aircraft contrail. Such shadows are three-dimensional dark slots hovering in the air.",
"To look for these on a sunny day with many contrails, just wait for one contrail to cut across the sun, or wait for it to drift until it crosses the sun. T... | [
"Wow. Thank you so much. I was kind of freaked out when I saw it :P I really appreciate it. "
] | [
"Much weirder is when the sun is trailing the plane from your perspective, so ",
"the shadow-slot juts out in front."
] |
[
"Has there ever been a comprehensive pain scale established."
] | [
false
] | The reason I ask this is because the age olde argument, of what hurts worse, came up with my girlfriend. We decided to turn to you for answers. Nut shot Vs. Birth. Go. | [
"I pass hundreds of kidney stones a year, here is my rating scale:",
"Noticeable pain",
"Annoying/nagging pain (when you start complaining) ",
"Painful pain (when you start taking stuff, applying heat/ice) ",
"Excruciating pain (when you start screaming, crying, rolling on the floor, puking, etc.) ",
"Imm... | [
"Or, you're a soldier and both your legs have just been blown off, but you're in shock and numb and give only a \"3\" because you don't really know what's going on. "
] | [
"I'd imagine because it's completely relative among a group of humans who all have different thresholds for pain. In emergency medicine, we always ask, \"On a scale of 1 to 10, 1 being no pain at all and 10 being the absolute worst pain in your life, how bad is your _________.\"",
"The problem is that most people... |
[
"Questions about the Placebo Effect"
] | [
false
] | I got a few questions I always wondered about the placebo effect or things I have heard about it and didn't know where true, hopefully I can get some answers here :D I heard if you know something is a placebo it still works? Does the method of placebo matter? (pill, injection ect) 2b. Does it matter if you gave the pat... | [
"Yes, this is true.",
"The method does matter. 2 Sugar pills are a more effective placebo than 1 sugar pill. A saline injection is a more effective placebo than a sugar pill. More dramatic 'fake' treatments are more effective placebos, so simply saying 'you're cured' is not very effective.",
" Actually I have n... | [
"I haven't downvoted them but the reasons for downvoting would include:",
"(1) it is true that being told you are receiving a placebo can result in a placebo effect: ",
"Placebos without Deception: A Randomized Controlled Trial in Irritable Bowel Syndrome",
".",
"(3) Administering yourself a placebo should ... | [
"Beg to differ on 3). Being involved in a clinical trial where you are given a placebo by a physician is substantially different from giving yourself a placebo."
] |
[
"What special procedures are involved in whole cell imaging by SEM or optical microscopes?"
] | [
false
] | I know it is more difficult to capture images of whole cells by optical or electron microscope. What exactly must be done to reveal a cell's morphology and microstructures? | [
"I'm actually midway through studying a couple lectures on microscopy in molecular and cellular biology!",
"Optical microscopes are pretty straight-forward when it comes to preparation. This is mostly because optical microscopes can't see things that are too small. The maximum ideal resolution for a standard brig... | [
"Obviously TEM preparation for something like a ceramic or polymer wouldn't be as difficult, but, other than actually cutting the ideal size and de-ionizing the surface, would you have to take any extra procedures?"
] | [
"Hmmm... I'm really not sure about microscopy of things outside my own field of molecular and cell biology. ",
"Feel free to have a read through ",
"Wikipedia's bit on TEM sample prep",
"."
] |
[
"We’re conducting research focused on modifying bacteria to make them slurp up heavy metal pollution. Mutating organisms for our benefit: Yay or nay? Why?"
] | [
false
] | null | [
"Have you tested it out on real copper spills? Perhaps you could find some and take them to your lab. It would be annoying for you if they couldn't survive other toxic conditions in the environment and essentially became rather expensive fertilizer."
] | [
"The copper contamination that we simulated in the lab was more concentrated than most that would be found outside.",
"You're exactly right; the next phase of research involves going out and getting real samples and working with the bacteria in them."
] | [
"Can you explain what the purpose of these bacteria is? What are you trying to achieve by adding these bacteria to a copper spill? "
] |
[
"How would an anti-matter black hole interact with a matter black hole?"
] | [
false
] | What would happen if a black hole from a matter star collided with a black hole made from an antimatter star? Would they explode normally? Would there be odd gravitational fluctuations? Could it warp space-time so drastically that it would create a wormhole? | [
"There is no difference between a black hole that arises from a matter star or a black hole that arises from an antimatter star. If two black holes collide, they just become one larger black hole and, in the process of coalescing, emit a whole lot of gravitational radiation."
] | [
"A black hole isn't composed of antimatter, or regular matter, for that matter... It doesn't matter what kind of star the black hole formed from, once it has become a black hole, it isn't matter anymore. ",
"The no-hair theorem states that a black hole can only be described by three externally observable characte... | [
"While we have not yet directly observed anti-matter falling towards the ground, there is no serious model in which anti-matter has \"anti-gravity,\" and here's a good way to see this.",
"Let's consider light. Light is made of photons, and photons are their own anti-particle. So if matter and anti-matter were in... |
[
"How did certain animals evolve from breathing underwater to breathing air?"
] | [
false
] | [deleted] | [
"The earliest air breathing fish lived in water all the time and had working gills. But they lived in swamps and stagnant ponds and places like that. Like most fish today, they probably swam up to the surface and gulped at air when the oxygen content of the swampy water decreased. This circulates water at the ae... | [
"I did a pulmonary physiology seminar a few years ago and read quite a bit about swim bladders. If I remember, teleosts evolved a pneumatic duct and eventually swim bladders, with a branch at some point between lungs and swim bladders. No organisms have both swim bladders and lungs. So I don't know if we can really... | [
"Bird lungs are indeed amazing. Did you know that bird-style lungs are believed to be one reason sauropods could have such long necks? Circular breathing really helps reduce the \"dead space\" problem and also provides better efficiency for giant bodies.",
"It would appear that the bony fish ancestral to both l... |
[
"How bright is the inside of the Earth?"
] | [
false
] | If there were a hypothetical transparent tunnel that passed through the diameter of the Earth, how bright would it be? Is there any particular part that would be brighter than the rest? | [
"How much light something gives depends on its temperature. This is called ",
"blackbody radiation",
" and is the reason why all hot objects give light (lightbulbs, hot iron, magma, the sun). The center of the earth is about the same temperature as the surface of the sun, so it would give of approximately the s... | [
"This didn't sound right, but I checked, and yoenit is right - the center of the Earth is theorized to be about 7000K, and the surface (photosphere) of the sun is 5800K. Note that the corona ",
" the photosphere is 5x10",
" K"
] | [
"The inside of the Earth isn't lava/magma, nor is it cold rock (which are the two things that a volcano is composed of). ",
"The vast majority of the inside of the planet is just heated rock (solid, not liquid - at least until you reach the outer core). I'm not going to speculate how much light might be released ... |
[
"If I pour a line of flammable liquid on the ground and light it, can you calculate the speed at which the flame will propagate?"
] | [
false
] | null | [
"The speed at which the flammable liquid propagates is essentially the speed at which the chain reaction occurs, which depends on many different factors that can be difficult to account for, but we know the gist of how certain individual variables will affect the speed of propagation of the flame. These three are i... | [
"My focus was mainly on the intrinsic properties of the liquid itself, but yes, there are a myriad of other influences, such as variations in oxygen levels, ambient temperature, wind, introduced impurities, exposed surface area to volume ratio, flow of the liquid, etc. that can be chaotic in nature or otherwise mak... | [
"I can probably make a weak-ass concept of a mathematical/computational model, based on ",
"/u/silberklinge",
"'s comment ",
"here",
".",
"Summary of what I'm trying to do: subdivide that line of flamable liquid (now known as \"petrol\") on the ground into many tiny segments, each one being a control volu... |
[
"How do attractive forces work?"
] | [
false
] | I understand (at least I think I do) how repulsive forces function at the quantum level, but I cannot find any explanation for attractive forces. Let's take the electromagnetic force, mediated by the photon. When two similarly charged particles come near each other, they exchange photons with each other and repel becau... | [
"Virtual photons are no billiard balls that charged particles throw at each other but are just mathematical relics that you get from solving the underlying process perturbatively.",
"edit: The ",
"posts",
" that ",
"u/Lagrangsch",
" linked contains a very good, more detailed explanation."
] | [
"It's an easy mistake to make when you see your first ",
"Feynmann diagram",
" to think \"Well that won't work for attractive forces\" but keep two things in mind:",
"First, the virtual photon can have negative energy and negative momentum. While that seems nonsensical to us in the macroscopic world, there's... | [
"It works the same. The source of your confusion is that you think of a photon as some ball that the first electron throws away from the second one, but still hits it. It doesn't work this way. A single photon with a fixed momentum is a plane wave, and a plane wave isn't localized in any region of space, it is ever... |
[
"Calculate home water psi from the time taken to fill a container. Is it possible to do this without a gauge?"
] | [
false
] | My wife is redoing the bathroom. She finds a shower head that require a minimum of 23 psi to function correctly. So my question is can this be calculated? If I were to know the diameter of the pipe the water was coming out of and then measured the time it took to fill a gallon container would that be enough information... | [
"I believe if you ring up your water supplier, they can just tell you.",
"23 PSI sounds very low, I believe the average household gets about 50-70, so you should be fine."
] | [
"Sure you can, it's known as the bernoulli principle or bernoulli's equation, check it out on hyperphysics for a good explanation (and there's a calculator that should suffice for your needs):",
"Bernoulli & Pressure",
"Also a quick gander at the wikipedia page will help. If you can come back to us with figures... | [
"Thanks for your reply. I actually have a comp. sci. background so I'm sure I can handle the math, just didn't know what equations, rules would apply. I'll figure it out this weekend, thanks again!"
] |
[
"Does trying a knot in a string increase or decrease its entropy?"
] | [
false
] | Strings will naturally tie themselves into knots, but doesn't tying a knot yourself take work? Is the work decreasing entropy? Is there a point where tying another knot would have the opposite effect? | [
"It would increase the total entropy since the process of tying a knot is not ",
"reversible",
" due things such as friction. ",
"I found a paper on this topic here: ",
"http://arxiv.org/pdf/1003.5134v1.pdf",
"We estimate by Monte Carlo simulations the configurational entropy of N-steps polygons in the c... | [
"An irreversible process can still have a net decrease in entropy, can't it? "
] | [
"In a closed system no, if its open, sure locally, but overall entropy increases."
] |
[
"Is there a way to properly measure pain?"
] | [
false
] | null | [
"Admittedly those are all still subjective measurements. If the OP was interested in some kind of objective measurement, then the answer is no. ",
"There is a strong psychological component",
" to how we experience pain."
] | [
"another prior thread"
] | [
"The Pain Scale",
", ",
"the Dolorimeter",
", and often seen on ",
"r/TIL",
", the ",
"Schmidt Sting Pain Index",
". The man who developed this index subjected himself to stings from all manner of creatures. Brave, brave man. Not sure where a box jellyfish falls on this scale, but from all accounts, I... |
[
"Nat gas vs oil"
] | [
false
] | [deleted] | [
"Oil and natural gas are formed from the same ingredient: the decomposed remains of microscopic organisms that lived hundreds millions of years ago. Sediments built up on top of these organic materials after they were buried, increasing the pressure on them and pushing them deeper into the Earth where they were hea... | [
"I deliberately left that out because we don't know the regional histories well enough to say how long the oil/gas was heated or to exactly what temperature. In addition, there's a very good chance that the oil/gas is not in the same place it formed - it seeps upward and laterally due to its low density until trapp... | [
"I deliberately left that out because we don't know the regional histories well enough to say how long the oil/gas was heated or to exactly what temperature. In addition, there's a very good chance that the oil/gas is not in the same place it formed - it seeps upward and laterally due to its low density until trapp... |
[
"How many different supernovae contributed the carbon on Earth?"
] | [
false
] | Is it possible that the carbon (for example) that ended up on Earth all (or mostly) came from the same supernova? If not, how many supernovae contributed to the molecular cloud that coalesced to form our solar system? | [
"There's a problem here with the initial question: interstellar carbon doesn't just come from supernovae. A very substantial percentage is produced from the mass loss of ",
"asymptotic giant branch stars",
".",
"Stars as small as half the mass of our Sun will undergo this phase near the end of their lives. Th... | [
"Just curious, stars half the mass of our Sun live a much longer time and can take more than 10 billion years to lose carbon in the way you described. Very massive stars on the other hand can become supernovae after just a few tens of million years.",
"Have there been enough generations of small and medium-sized ... | [
"Oh, I don't doubt that the carbon COULD cone from one star. I just wonder how much mixing is going on."
] |
[
"Can someone tell me how to read this chart?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"A good home for this question is our sister subreddit ",
"/r/AskScienceDiscussion",
" because of its open-ended or speculative nature. Please feel free to repost there!",
"Please see our ",
"gui... | [
"It's not speculative, I'm just asking how to read a chart."
] | [
"Sorry for the canned answer. It's a prewritten thing.",
"/r/AskScienceDiscussion",
" woudl be more appropriate for your question as you are asking about individual help understanding a paper. ",
"r/askscience",
" is more for general science questions. ",
"Btw your link is broken."
] |
[
"What would the timespan be for the majority of earth's population to be 'new' people?"
] | [
false
] | Here on Earth, a bunch of people die everyday and a bunch of people are born everyday. To explain my question in simple terms, if there were ten people on earth and one person died everyday and one new person was born everyday, it would take 6 days for the majority of the population to be new i.e. the majority of the p... | [
"This is a sort of standard demographics/population biology question; I tried to answer it just now naively, assuming exponential mortality, but got a silly answer; you'd need to have the actual data from ",
"tables like these",
" along with a profile of current demographics and do some calculations on them.",
... | [
"The World Bank reports global life expectancy in 2010 to be 69.6 years."
] | [
"Wow, that's great. I'm glad it peaked your interest. Over the course of the question being posted, I started to realise it might've been more relevant to simply ask:",
" ",
"Going off your 40 year calculation, do you think it's fair to say that by 2040 we will be close to that reality?"
] |
[
"electric potential question"
] | [
false
] | [deleted] | [
"You'd pretty much just be adding 100V to the field everywhere, and to all your calculations. Remember that the observable quantities (the electric and magnetic fields) depend on derivatives of the potentials, so adding a constant doesn't affect anything."
] | [
"Ye. It doesn't even matter if you use \"affect\" or \"effect\"."
] | [
"Nice."
] |
[
"How could vacuum energy cause the expansion of the universe?"
] | [
false
] | [deleted] | [
"Because it has negative pressure. As a matter of fact, not only it has negative pressure, as the pressure has the same magnitude as the energy density, which means that, once you do the calculations, you realize that no matter how you stretch the universe, the vacuum energy will still make it stretch even further.... | [
"What is negative pressure?"
] | [
"I believe it's everything explained in here (it's about inflation, but the idea is the same)",
"http://theory.physics.helsinki.fi/~cosmology/cosmo2012_09.pdf"
] |
[
"When looking at text through a wine-glass filled with water, why are the text both reversed AND upside down?"
] | [
false
] | I recently watched a video regarding , and the concept of the light refracting through the glass and water to flip the image/text behind it horizontally was easily understood. Last night I coincidentally saw this phenomenon when a friend's wine-glass was put in front of my pc's monitor with the digital-time showing beh... | [
"Is it correct to assume that this is because of the shape of the glass?",
"Yes, but more importantly, it's because of the shape of the ",
"When there is no water in the glass light basically passes straight through, almost regardless of the curvature of the glass because the glass is very thin. The image behin... | [
"Thanks for the thorough reply!"
] | [
"One more interesting thing, because the glass is acting as a lense it has a focal point. If you move the glass close enough to the screen, the text should flip back around to normal. "
] |
[
"Is it possible for a planet to have a sun orbiting it, rather than the other way around?"
] | [
false
] | Can a planet scale up, or a star scale down, to the degree that the relationship we experience on our planet, is reversed? | [
"All big planets we have found so far consist of a large fraction of hydrogen. This means that if you would grow to the size of a star it would simply ignite and become a star."
] | [
"centowen's answer and ion_ion's follow up are essentially correct, but let me expand a little:",
"A celestial body's size depends on its mass and composition. If a planet were to simply be scaled to the mass of the sun, there is its composition to be considered. A star like the sun only has its size because of n... | [
"The Sun and the planets both orbit a place 'between' them. The caveat is that the Sun is so much more massive that this point is beneath its surface for all but Jupiter. ",
"In essence, the Sun also orbits the center of mass of this system, just as the planets do, it is just an extremely small orbit.",
"That b... |
[
"What is the tallest structure that can be built to have humans be transported to the top? Not a skyscraper. Just a tower with some kind of elevator to get as high as we can go without being in an aircraft."
] | [
false
] | I hope I'm explaining it right. If we wanted to make the tallest tower for humans to go up to, how high could we get? If I wanted to put elevators so that people could visit, would this be possible? What would be the major obstacles to go through? | [
"At the moment, the tallest structure in the world is the ",
"Burj Khalifa",
" building in Dubai, UAE. It stands as about 830 meters, though nearly two hundred meters of it isn't for human occupation. ",
"The answer to this questions is currently about a kilometer is as high as you can get with today's techn... | [
"The idea predates Carl Sagan. Per wikipedia the idea of the ",
"space elevator",
" dates back to the 19th century and Konstantin Tsiolkovsky. I remember being introduced to the idea with Arthur C. Clarke's novel ",
"."
] | [
"It's even simpler than that.",
"\nThe space elevator (cable + counterweight) is a mere satellite, whose center of mass is moving along the geostationary orbit. ",
"The fact that its lower part reaches the Earth ground doesn't change the way its center of mass moves along its orbit."
] |
[
"Isentropic compression in plain language?"
] | [
false
] | I've come across a passage in a memoir by a nuclear weapon designer which states: In August and September, Ron and I worked day and night to design an even more radical nuclear device. We further optimized the pulse shape to achieve practically isentropic fuel compression. It's the latter that I am just not 100% sure I... | [
"Isentropic means constant entropy. ",
"If the entropy of a working fluid doesn't change over the course of a process then the process is said to be isentropic. ",
"Reversible processes that are operated with zero heat transfer (q=0) are isentropic by definition."
] | [
"Probably..."
] | [
"Thanks. So is it likely correct to interpret the quote as saying that they managed to make a bomb design that resulted in compression of fuel with near zero heat transfer? "
] |
[
"Was the first second of the universe identical to a second passing just now?"
] | [
false
] | I remember Steven Hawking describing what the first second after the big bang was like and I just want to know, given the curvature of spacetime being so much less now, has time itself changed at all since it's beginning? | [
"time only runs at 1 speed. Time is relative, but it is fixed. ",
"the atomic decay rate of Cesium (on which a second is based), has not, and never will change. (though Cesium didnt exist in the first second, but if it had, it would have decayed the same rate as it does now)"
] | [
"I don't think that last part is true, aren't the nuclear force coupling constants energy dependent?"
] | [
"In the early universe it becomes useful to think of time in logarithmic units (so comparing 1 to .1 and .01 instead of 2 and 3). This is because a more useful measure is energy scale instead of time after the big bang. It seems a little weird to think that vastly different physics was happening a nano second after... |
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