title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"How would one calculate the partitioning of water between two hygroscopic materials in a sealed chamber with a known volume of water vapor?"
] | [
false
] | null | [
"place both the materials on a balance, record. then put them in the sealed chamber for a very long time to reach equilibrium. record the difference. that is the amount of water that went into each."
] | [
"Good idea. I imagine it would work assuming both materials were approaching 100% water-less beforehand. ",
"But there must be equations governing the system in question. And surely there'd be some amount of water vapor left in the gas within the hermetic chamber. I'm wondering if anybody can point me towards... | [
"while it might be hard to get to 100% free of water if you put the material in a dessicator, or a vacuum oven if it is thermally stable at elevated temperatures, you could get it quite dry. The reason why you want to leave the system undisturbed for a long time is that the system will tend to equilibrium (It would... |
[
"How are proteins in their tertiary structure stabilised by the \"hydrophobic effect\"?"
] | [
false
] | The lecturers at my uni aren't too great at explaining this | [
"Proteins exist in an aqueous environment, and water itself is a polar molecule, that is, there is a separation of charge on a water molecule. The oxygen is negatively charge, while the hydrogens are positively charged. ",
"Now you through a protein into the mix, which consists of a long chain of different amin... | [
"Tertiary structures are really stabilized by the hydrophobic effect by the removal of nonpolar groups from the aqueous environment, and are a consequence of the polarity. The polarity of the functional groups are what contribute to the structure of the protein, and are what provide the shape and, consequentially, ... | [
"This is an excellent answer.",
"It's also worth noting that the laws of entropy still apply in protein folding and stability - that systems moving towards a disordered state are inherently favourable.",
"Although it might seem counter-intuitive for a tightly folded protein to add to the disorder of a system, i... |
[
"Why don't dogs live as long as humans? Are we increasing their life expectancy as we increase ours?"
] | [
false
] | null | [
"The answer is yes; but mostly no.",
"Let me explain; in the future our medical knowledge will increase; including that for animals and we will be able to tailor diets, medical knowledge, and medicine to enlongate life for dogs, cats and humans.",
"However life expectancy is not due to medical knowledge; well t... | [
"Less resources available to your family, and to a greater extent, your immediate community/tribe if you're still around consuming them. "
] | [
"Less resources available to your family, and to a greater extent, your immediate community/tribe if you're still around consuming them. "
] |
[
"why do the low notes on a piano carry for much much longer than the high notes?"
] | [
false
] | if you slam an A in the first octave and an A in the last octave, the former will continue to output sound for much longer than the latter. why is that? | [
"Because the energy in the vibrating piano wires dissipates a small percentage each vibration. So the note 'lasts' not a period of time, but a number of vibrations. Lower notes period of vibration is longer. So they last longer too."
] | [
"And the lower note strings have the highest mass/unit length so they store much more energy than the much thinner high note strings."
] | [
"It's likely more due to internal friction than aerodynamic drag. The vibration of a string in vacuum would still attenuate in the same way."
] |
[
"Do deaf schizophrenics hear voices?"
] | [
false
] | I was reading a cyanide and happiness comic that jokes about this and raised the question, what happens with a deaf schizophrenic? | [
"According to my Abnormal Psychology Textbook, \"using SPECT (Single photon emission computed tomography) to study cerebral blood flow of men with Schizophrenia, researchers in London made a surprising discovery. They found that the part of the brain most active during hallucinations was Broca's area. This is surpr... | [
"Please keep discussion:",
"Civil",
"On topic",
"Free of anecdotes"
] | [
"Wow - that's incredible and I didn't know that. Years ago I read ",
"The Origin of Consciousness in the Breakdown of the Bicameral Mind",
" and found the theory to be fascinating even though it technically would be non-testable.",
"What you're saying supports the idea that conscious thought evolved post-spe... |
[
"May be a dumb question, but do stars of the same mass also have the same volume?"
] | [
false
] | Given that stars are mostly made of the same stuff (hydrogen and helium) and gravity is only dependent on mass, I figured equal stellar masses would have similar densities. | [
"Depending on the point in their lifecycle they have different ratios of hydrogen/helium/other elements. Stars of the same mass and the same composition are very similar."
] | [
"This answer is good.",
"For ops benefit I'll add that temperature is variable that affects density as well. A star that's burning hot has great outward pressure against gravity and so a larger volume. ",
"Vzq's lifecycle/composition comes into play here: As a star gets old it runs out of all that good H/He fue... | [
"The answer is, as all good answers in science are, it depends. ",
"Stars on the main sequence (the predominant life stage of stars) generally follow something called the ",
"mass-radius relation",
". This means, for a given mass, all stars will have approximately the same radius, within error of course. So ... |
[
"How is it possible for scientists to study and discover about things millions or billions kms away from us when we haven’t even discovered everything that is in our planet?"
] | [
false
] | null | [
"Why are those things mutually exclusive?"
] | [
"I don't really know what kind of answer you are looking for... we have telescopes?"
] | [
"We do send underwater vehicles to explore the deep ocean and we have detailed atlases of the ocean floor... Again, I'm not really sure what you are trying to ask."
] |
[
"If starlight is extremely old, if someone were to get into a spaceship and fly towards a very distant star, would that star seem to age very rapidly as the ship approached?"
] | [
false
] | I know that many stars are many lightyears away from the Earth, meaning that the light that reaches us from them is old, often very old. If we were to fly towards one, would that star seem to age at an accelerated rate of viewed from the ship? | [
"All stars except our sun are very many light years from earth. The closest star (other than Sol) is Proxima Centauri at 4.2 light years. The farthest object we've seen is about 13.2 (updated from my mistaken 13.7) billion light years away.",
"So the answer is yes to your question. If we look at Proxima Centaur... | [
"You can not travel faster than the speed of light. In fact, as a physical object (with mass) you can't attain the speed of light at all."
] | [
"Light always travels towards you at c. But when you fly towards the star at high speed, space seems to contract, so the light is covering less distance to get to you.",
"So the answer must be yes, flying towards a star will make it seem to age very rapidly."
] |
[
"Would it be possible to have a Jupiter sized Earth-like planet?"
] | [
false
] | in science, started me wondering about planetary scale. Is it possible for solar systems to scale in such a way that an Earth-like planet could be the size of a gas giant in our solar system? *Could there be a habitable planet the size of Jupiter somewhere floating among the cosmos? | [
"~1000 Earth Masses of metals is about the most you can hope to find around a solar type star for planet formation. ",
"COROT-20 b",
" may be such a planet, although it also has ~3 Jupiter masses of gas on top of the hundreds of Earth masses of rock and ice, so you'd probably call it a Jupiter type planet.",
... | [
"Exactly. Even Venus has a surface pressure equivalent to being under 1km of Earth's oceans because of it's thicker atmosphere. But even if we assume that the atmosphere on a hypothetical Jupiter sized terrestrial planet is proportional in thickness to Earth's atmosphere (or even the same thickness as Earth's), the... | [
"It's not within our abilities today to start a terraforming project. In the longer term, her comparable surface gravity makes Venus an ideal target for terraforming, yes. When? I wouldn't know how to speculate. More than ten years, less than a thousand?",
"Maybe I shouldn't be negative, but if the Earth has ... |
[
"Are there colors that do not present themselves in animals and plants? Or is there a least common color in the wild?"
] | [
false
] | null | [
"There's not a great numberl of blue animals in nature and human eyes respond least well to blue frequencies."
] | [
"If you look on the electromagnetic spectrum, \"visible\" light is a tiny portion, bordered by the UV/Gamma and Infrared/Microwaves. Obviously, all of these frequencies are of light, it just happens that that tiny portion is what our eyes can pick up. So if our eyes were capable, theoretically we would be able to s... | [
"Not sure if this is what you are getting at but as far as I know there is only one species of mammal, a mole, that has iridescent fur."
] |
[
"Why do lower frequencies penetrate materials better than higher frequencies?"
] | [
false
] | For example, sound and radio waves (WiFi) | [
"Other people gave answers for light, but the answer for sound is slightly different.",
"Ultimately it comes down to wavelength. For sound passing through a wall, if the wavelength of the sound is much larger than the thickness of the wall, then the wall will appear to be like a thin membrane and will move in its... | [
"If a photon doesn't have enough energy to raise a particle of the matter its \"penetrating\" to a higher energy level, then the photon just passes through.",
"Which means that higher energy photons interact with more particles.",
"Higher energy means higher frequency.",
"So lower frequency waves \"penetrate\... | [
"Wow. Thank you."
] |
[
"AskScience AMA Series: IAmA PhD student who manipulates microscopic particles using light"
] | [
false
] | I am a third year PhD student (in the UK) who works daily with optical tweezers. My research interests lie in soft matter and specifically colloid physics. The bigger picture in my work is understanding of the glass transition. Optical tweezers is a technique developed in the 1980s whereby the forces due to a single, t... | [
"Can you describe your research a bit more? What size/type of colloidal particles do you use? Do you move them closer to each other until they look glassy?",
"Do you deal with/care about colloidal crystals that are held together with DNA?",
"Were you at the ACS Colloids conference in Montreal last summer?"
] | [
"My research: I've described a little in my first answer, at least regarding my use of optical tweezers. Colloid-wise I use commercial polystyrene microspheres in the 2 to 5 micron range as well as smaller poly-methylmethacrylate particles synthesized in our lab. My experimental procedure is to use optical tweezers... | [
"Firstly: the glass transition. I don't know about the rest of the world, but I certainly remember being taught about the differences between solids, liquids and gases in secondary school. Microscopically, we were taught, the particles of a liquid are randomly arranged while the particles of a solid form a regular ... |
[
"What is the use of the laser in laboratories?"
] | [
false
] | I've seen them in movies and shows and many real life experiments but I never got what they were, can someone explain? | [
"Light (or more generally radiation) from a laser has several properties which can make it very useful for laboratory research. The light is ",
"coherent",
" which means (among other things) that interference can be observed. It can also be (almost) completely monochromatic so the light source contains waves ... | [
"An example I can think of off the top of my head is ",
"Laser Spectroscopy",
".",
"Transient absorption is probably the easiest to explain of this type. Basically you hit your sample with a fast, high intensity pulse of laser light. You then monitor the absorbance spectra of the sample. This allows us to inv... | [
"It's what my wife does. I call her an electron photographer. She calculates \"the migratory pattern of the elusive silicon conduction electron\" (to be said in a NatGeo presenter voice)."
] |
[
"Why does a capacitor eventually have the voltage of the connected battery?"
] | [
false
] | When a capacitor collects negative charge on one plate, it repels further incoming current, and also repels the negative charges on the other side of the plate so that the second plate is positively charged. So additional electrons will be repeled by the negative plate but shouldn't they also be attracted to the positi... | [
"So additional electrons will be repeled by the negative plate but shouldn't they also be attracted to the positive plate?",
"Yep, until the attraction and repulsion are balanced out by the voltage. (The battery also applies a force on the electrons, in addition to the electrostatic forces between the plates and ... | [
"As long as it ",
" have the voltage of the cell or battery of cells to which it's connected, there's a conductor (ie whatever is connecting the capacitor to the cell or battery) with a potential difference across it ... so current flows through it in such a way as to increase the charge of the capacitor."
] | [
"Awesome, everything makes sense now. Thanks all!"
] |
[
"Do sleeping pills decrease the quality of sleep?"
] | [
false
] | I know that we don't really know a whole lot about what goes on during sleep, so I'm curious if there's any way to quantify a change in quality of sleep when it is (at least partially) artificially-induced. I'm thinking of mainly OTC sleep aids (diphenhydramine) but I'm also curious about stronger prescription drugs. | [
"There's are a number of ",
"different sleep aids",
" that influence sleep architecture quite differently. Acute insomnia can sometimes be remedied by various benzodiazapines or Z-drugs - Z-drugs are similar to Benzos but have reportedly lower dependency rates- like Zoplicone. These drugs tend to influence delt... | [
"First off, awesome summary. I'd like to summarize and add a few things though.",
"Let's talk about levels of sleep (from awake to REM)-\nWe have N1, N2, N3/N4, and then REM. Generally, N3 sleep (or deep sleep) and REM are considered the most beneficial. N3 sleep is thought to be restorative to energy, and REM... | [
"Well melatonin can be used as a alternative way to help correct sleep rhythms. For example, one study found that the circadian shift elicited by weekend sleep patterns can indeed be corrected with the use of melatonin (",
"cite",
"). However its corrective properties are heavily dependent on when the compound ... |
[
"Why do cats love to sit in boxes? No, seriously. Why?"
] | [
false
] | We're all aware of the phenomenon. Place an open box in the middle of the room. Or even something flat like a newspaper. And sooner or later your cat will sit on it like a watchtower. So why is this? It's not particularly warm, soft, or high up. Is there some natural behavior that domesticated cats are mimicking when t... | [
"Boxes allow at least partial concealment. Cats may enjoy that because they're both ambush predators and small animals that need to watch out for predators. ",
"I don't think cats have such a strong preference for flat objects like newspapers. Maybe it is just memorable when a cat sits on an object but not mem... | [
"I don't exactly know how to respond to this thread. I think we can learn a valuable lesson here about how anecdote can contribute to on-topic discussion on this forum. ",
"First, as to the question, I too have cats and anecdotal evidence from that experience. We can combine our several experiences to comprise a ... | [
"my cats will also jump at the opportunity to sit on a newspaper or plastic bag in the middle of the room, but I think more than anything, it's just that it's new. They walk by and say, \"Hmm. That wasn't there before. Better investigate,\" and apparently cat investigation mostly involves sitting on things. "
] |
[
"Should I speed up or slow down to decrease the chance of my car being blown off the road?"
] | [
false
] | My sister is in northern Ontario, where I hear it is a fairly blustery day today. My assumption would be that speeding up would provide more kinetic energy while decreasing the available traction. Would the decrease in traction be worse than the increase in momentum? | [
"This may not be scientific information but it well tested empirical data. Slow down! Here is why. If the wind takes you for a bit of a ride you may be able to find an escape route before you have a real problem. In general if the situation is unsafe or even in question, slow down. Now, on with the science. T... | [
"How your momentum affected the wind would depend on in which direction the wind was blowing and the direction in which the car is moving. Momentum is a vector quantity. Assuming that the wind was directly perpendicular to your car, the momentum of your car due to its moving forward would have no effect on the wind... | [
"This is what I was suggesting also. I am actually not sure why I was down-voted, as I used actual physics to back it up, and you were upvoted for anecdotal evidence. Speeding up does almost nothing except make it more dangerous if you get blown off the road."
] |
[
"Left a container of white rice in the fridge too long. It turned green/blue moldy. Where does the pigment come from?"
] | [
false
] | Can pigment be formed from two substances that doesn't contain the color? | [
"... you know, for a friend."
] | [
"How much moldy rice would someone need to eat in order to cure a case of syphilis?"
] | [
"I could be wrong, but this seems like a variation on the question \"when I drink purple grape juice and pee yellow, where does the purple go?\"",
"When molecules of any colour are metabolised, they are broken down into simpler bits and reassembled to form new molecules with new properties that could include a di... |
[
"What is the evolutionary point of photosynthesising vitamin d?"
] | [
false
] | null | [
"Human body"
] | [
"Human body"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"If you disagree with this decision, please send a ",
"message to the moderators."
] |
[
"Genetic mutations and errors in DNA replication?"
] | [
false
] | 1.) I understand that a silent mutation always affects the genotype and not the phenotype, but considering an alternate base pair is replacing an existing one (but still not changing the amino acid), isn't it fair to say that silent mutations do produce a change in the primary sequence of the encoded protein? (Example:... | [
"A is the correct answer because it is referring to a ",
" of organisms, not a single organism. On the whole, the ability to mutate is advantageous because it allows, every once in a while, for an organisms in a population to acquire a positive trait.",
"Also, to clarify on the last point. Transcription and tra... | [
"1) The base pairs tell specific RNAs what amino acids to recruit, ",
" which one to produce. Since silent mutations result in the same amino acid being recruited, the protein does not change.",
"2) I think you are misquoting your professor, especially since you only put part of what he said in quotes. I don't ... | [
"Thank you so much for your clarifying that for me. I appreciate your help. ",
"For number two though, the question actually read \"Considering the ability of a community of organisms to adapt to the environment: A.)mutations are advantageous B.) mutations are disadvantageous C.) Both are correct\"\n*According to... |
[
"Could you make some sort of 'boat' to float in the atmosphere?"
] | [
false
] | [deleted] | [
"Boats on water float because they are buoyant. Buoyancy occurs when the object weighs less than the stuff it's displacing. To create something that's buoyant in air it necessarily has to be lighter than the air. The easiest way to do this is with a gas. To contain a gas in your craft it would have to be sealed.... | [
"No, but ",
"this",
" is a pretty cool video of an aluminum foil boat floating on sulfur hexafluoride. "
] | [
"No solid or liquid is lighter than air. ",
"Good response, but this one part isn't entirely true. There are effective solids that are lighter than air, and I suppose they could be fashionable into a boat. That's being a bit nit-picky of me though.",
"Another thing to note is that buoyancy on water is easy beca... |
[
"Probably a very basic question about evolution..."
] | [
false
] | Probably just exhibiting my ignorance here, but natural selection via mutation would surely produce a lot of "failed" mutations right? In fact it must logically be something like 99% of mutations. Surely there should be many more "defected" organisms showing up in the fossil record? | [
"Most deleterious mutations wouldn't survive the egg or the womb. Most of the rest wouldn't survive infanthood, and so on. There not being many mutations to start with, the number of deleterious mutations surviving long enough to be trapped as fossils would be very small.",
"These two penguins are slightly differ... | [
"Fossilization is a rare event. The odds of any individual of a species becoming a fossil are low, and there were undoubtedly species that never left a single fossil (or that we haven't found yet). In general, the more common a species is, the more likely one of its individuals will leave a fossil.",
"Think of ... | [
"Most mutants (with harmful mutations) can be expected to be less physically fit than a healthy dinosaur. A less fit dinosaur is even more likely to be eaten, and its body destroyed. ",
"Edited to clarify that a mutant would need a harmful mutation to be less healthy"
] |
[
"In a vacuum, will an electron cloud expand to fill a volume like a gas?"
] | [
false
] | null | [
"In a sense, yes. If you have a particle in a box and you expand the size of the box, the wavefunction of the particle will evolve with time such that it \"occupies\" the entire available volume.",
"There are two limits to consider: the limit where the box is expanded rapidly (the sudden limit), and the limit whe... | [
"There is no hard cutoff, these are just limits where the time-scale for the perturbation go to zero (sudden) or infinity (adiabatic) respectively."
] | [
"The probability density will not be uniform. The energy eigenstates for a particle in a box are sinusoidal. So there will be nodes and maxima in the probability density, but the wavefunction will still \"occupy\" the whole box."
] |
[
"Is there anything in what this guy says? (Some probably insane youtube video about the magnetosphere)"
] | [
false
] | TL;DW - This guy is saying data is missing from the magnetosphere data on the NASA website for March 12th 2012 and that it may be a magnetosphere reversal? (Which, in my laymen head, doesn't make sense since I thought the magnetosphere didn't really have poles). Just curious whether this is crazy or could make sense? | [
"The guy doesn't seem to postulate what the cause is of the event, just that there appears to be a reversal that occurred and that the data for this time frame has now been removed.",
"I am not an expert on this field, but I will say that it is not uncommon for experimentalists to hide data of interesting events ... | [
"Due to the solar wind, the magnetic field lines are distorted from what would be approximately symmetrical shape, into one that is 'drawn out' into a tail facing away from the sun. It seems that by reversal he means that he believes something on the dark side of Earth distorted the field to face in the opposite d... | [
"Perfect answer, I didn't know they do that. Thanks!\nKinda backfired though if they did it for the second reason lol There's quite a few sites/videos about it.",
"Oh and also what I meant for the reason was, is there any reason it would reverse or could?"
] |
[
"How do astronomers know how far a star or galaxy is from us?"
] | [
false
] | [deleted] | [
"A few different ways;",
"Lasers",
"Parallax",
"Standard candles",
"Red Shift",
"For more detail on how astronomers measure distance this Wiki page has a good list of techniques;",
"https://en.wikipedia.org/wiki/Cosmic_distance_ladder"
] | [
"Good list. I would add that Cepheids/variable stars are also used as standard candles (it says so at the link, but might be worthwhile to mention explicitly, since this method (discovered in 1912) was the first standard candle)."
] | [
"And there's also two main types of Cepheids, which need to be differentiated in order to accurately determine their distances. The reason why they work so well as distance indicators is because their brightness is directly proportional to the length of their pulsation period (the time it takes for the star to ret... |
[
"Why do all the planets roughly orbit the sun on the same equitorial plane and also the same direction?"
] | [
false
] | This bugged me for years and I still can't find a satisfactory answer. | [
"They all formed from the same accretion disk so they rotate on the same plane and in the same direction that the original disk rotated in. "
] | [
"The search bar is your friend. This question gets asked almost on a weekly basis ",
"http://www.reddit.com/r/AskReddit/comments/ijote/what_causes_the_planets_to_orbit_the_sun_on/"
] | [
"It is thought (and now substantially confirmed by observing such phenomena from afar) that forming solar systems go through a period in which the young star is surrounded by an \"accretion disk.\" Enormous amounts of dust and gas avoid either being pulled into the star or drifting off into interstellar space by m... |
[
"The World's Population is circa 50% male, 50% female. What, if any, biological mechanism ensures such a ratio between the genders?"
] | [
false
] | [deleted] | [
"I cannot give you an expert answer, but while you wait for one you might like to read this wikipedia article.",
"http://en.wikipedia.org/wiki/Fisher's_principle"
] | [
"Related question",
".",
"Do some men have a higher count of sperm carrying a Y Chromosome than they do carrying a X chromosome?"
] | [
"circa is latin for \"around.\" I've seen circa used for other things than time."
] |
[
"Ignoring computer power, is there a maximum limit of the speed of the internet?"
] | [
false
] | Like with the fastest computer/router would we have theoretically infinite speeds? | [
"One person answered in terms of speed and the other person answered in terms of bandwidth.",
"Bandwidth (really ",
"symbols per second",
" is limited by how quickly you can meaningfully vary your signal. This is capped by the frequency of the light you are using to send the signal and how much noise there is... | [
"High-speed trading is interested in every millisecond reduction in ping. There are microwave transmitters set up because microwaves in air travel faster that infrared in fibers. And if it would be feasible today they would send neutrino beams directly through the Earth to avoid delays from the curvature."
] | [
"Any scheme to speed up a signal beyond that will fail, and if there's anything you think would allow you to then you should probably go back and be sure you understand it.",
"There is one other theoretical way, though it would likely induce high latencies in signal generation and detection. If we could figure ou... |
[
"How many calories are burned by donating blood?"
] | [
false
] | If course most is burned in replacing the blood cells, but how many calories are involved? | [
"Edit...I may have ",
" misunderstood OP's question. My answer below stays. ",
"According to the University of California, San Diego, your body does burn roughly 650 calories during the replenishment process after donating blood, as it must first increase your blood volume again, which takes less than two day... | [
"In my state, you can only donate whole blood every 8 weeks, because that is the conservative estimate for how long it will take until all of your red blood cells are replaced after donating. This puts you at 650 calories extra that are burned during 8 weeks (in theory), which technically averages out to only abou... | [
"Is there a frequency and volume at which you could donate blood such that it is safe yet contributes to weight loss? Not that I'd advocate it instead of healthy diet/exercise, but I'm curious. I'm referring specifically to the calories burned through replenishing the blood/cells rather than the actual act of givin... |
[
"Can someone explain FTL in general relativity?"
] | [
false
] | Lawrence Krauss says at 51:10 minutes in his "A Universe from Nothing" lecture that eventually galaxies will move away from us faster than the speed of light and disappear. I've been doing a bit of reading and am beginning to understand this concept, but can someone explain it to me in more simple terms so that a non-s... | [
"Lawrence Krauss is actually wrong on this one. At any point in time, sufficiently far galaxies will recede with speeds greater than the speed of light. The threshold distance for this is the Hubble distance, d = c/H. If you plug this in to the Hubble law, v= d*H, it's easy to see that v>c for these galaxies.",
"... | [
"If the acceleration continues, in the future the galaxies will seem to recede faster than the speed of light, even though they are not actually moving FTL. It's just that the light emitted from those galaxies will never be able to reach us given the speed of the expansion. ",
"Galaxies beyond the Hubble sphere d... | [
"Try this Khan Academy video:",
"http://www.khanacademy.org/video/radius-of-observable-universe?playlist=Cosmology%20and%20Astronomy"
] |
[
"Is it possible to store analog information on a microchip?"
] | [
false
] | I’m curious about modern analog information storage, which aren’t magnetic tape, optical, etc Could anyone point me to more information on this technology if it exists? I have read some about memristors and phase change storage, but that uses a special type of glass. | [
"Yes, by converting to digital and storing that. Sorry if that sounds cheeky (or even assholey), but it is actually the best answer to your question since the digital signal will result in the most accurate reproduction of the signal; this is what I will justify here.",
"The main reason that digital will outperfo... | [
"You can buy specialized ",
"sample-and-hold components",
" that store an analog voltage. ",
"Similar circuits",
" can also be built from individual components. ",
"Before microprocessors became fast enough to handle sound, audio delays were made using ",
"bucket-brigade devices",
". They worked by tr... | [
"Yes. Some researchers have developed a chip for neural nets, where each cell / transistor can be set to a continuous (= analog) resistance. In practice, the values of resistance will exist as digital information before being programmed as analog information on the chip, but the storage really is analog.",
"Sourc... |
[
"How does a drug ever completely leave your system if it just keeps decreasing by half?"
] | [
false
] | If a drug has a half-life of 1 day, then after a day, its amount has decreased by half. After another day, you’re at 25% and so on. But if it just keeps reducing by half, how do you ever reach zero? You don’t. It would be a tiny tiny minuscule amount but never zero, so I’m very confused. | [
"Molecules of drugs are discrete units. Each unit has a certain chance over time to be eliminated from the body through whatever mechanism it’s metabolized. Half-life is simply a description of the rate of that process. Ultimately, you end up with some small amount of drug (theoretically, one molecule) that is elim... | [
"Thank you, this helps a lot!! You can’t have half of a molecule"
] | [
"See also ",
"Achilles and the tortoise."
] |
[
"Has Io ever been seriously considered a possible site for extraterrestrial life?"
] | [
false
] | In Arthur C. Clarke's "2010", humanity finds extraterrestrial life for the first time on Jupiter's moon Io. In the years since, I can't recall any "real" cases for Io being a likely spot to find life in our solar system other than Earth. Has Io ever been a serious candidate for finding life? If not, why did Clarke choo... | [
"Interactions with Jupiter’s magnetosphere expose Io to some very intense radiation, and gravitational interactions with Jupiter tidally heat it’s core to the point where it’s highly volcanically active. Through a combination of the radiation and the heat any water that was once on Io is long gone, and it’s genera... | [
"\"Io is generally considered a poor candidate for life because of all the radiation Jupiter blasts it with. In addition, no organic molecules have been detected on its surface, and it has only an extremely thin atmosphere devoid of detectable water vapor.\"",
"https://www.space.com/8564-jupiter-volcanic-moon-io-... | [
"He wrote that in 1982. A few years after Voyager revealed that it was geologically active. ",
"But this was before a lot of science from the likes of The Galileo and Cassini-Huygens and New Horizons missions. It’s important to put his fiction in context with the knowledge that was available to him at that time, ... |
[
"Why are all adults prescribed the same dosage antibiotic regardless of weight?"
] | [
false
] | I recently ran a course of cefdinir, which was the first time I had taken this particular antibiotic. As I was poking around online reading about it I noticed that dosages for children under 12 are based on weight. So many mg per Kg. That leads me to my question as to why adults aren't also dosed like this. It seems a ... | [
"Children have immature organ systems and have to be dosed accordingly. In theory a child's body weight should be fairly proportional to their actual growth development. Adults regardless of size should have a fairly standard efficiency in regards to organs such as liver and kidney clearances. A 500 lb man is going... | [
"Depends on the drug. Every drug has two doses - the dose where it starts having the desired effect (killing bugs, in this case) and a dose where it starts causing problems (mostly tummy upset for cephalosporins). These doses are found out by trial and error and can later be calculated from body weight, lean body w... | [
"Doc here. Adult human easily range in weight from 90 or so pounds to 500+. There's actually not a lot of evidence-based guidelines out there for weight-dosing antibiotics and it's really difficult in the clinical setting to get a blood level on most antibiotics you're prescribing. So much of what we end up doing i... |
[
"Should mathematical models make qualitative or physical sense?"
] | [
false
] | [deleted] | [
"Paul Dirac ",
"wrote",
": \"it is more important to have beauty in one’s equations than to have them fit experiment\". I'm not sure everyone would agree with that, though :)",
"I'd say it depends on what you mean. If you're talking about finding an empirical relationship, just some equation that reproduces o... | [
"Paul Dirac is a good one to quote for this question, but not in the way you quoted him. Isn't he a bit notorious for his Large Numbers Hypothesis, where he basically is just playing with numbers to see the answers he wants?"
] | [
"Not exactly, if I understand what data mining is. Dirac found relationships between physical constants of the universe, which are assumed just to be numbers, not patterns in collected data. Maybe the same ideas apply though? Not sure, I'm definitely not an expert on either of those things."
] |
[
"Questions about perpetual motion."
] | [
false
] | [deleted] | [
"What exactly is perpetual motion?",
"Motion with no energy input.",
"Why is it impossible?",
"In practical terms, friction. In general terms, no process can convert/transfer energy with 100% efficiency, so some is always lost, meaning any system eventually loses usable energy over time without an input from ... | [
"Ok so what about a machine that is powered once via electricity and then uses that to power it self forever?",
"It's okay to have some initial energy input, the important thing is that you can disconnect your machine from anything external and have it run indefinitely.",
"EDIT: sorry I'm not giving more inform... | [
"Unfortunately no, it wouldn't. The generator will not be 100% efficient, so it can't collect all the energy from the wheels and so can't feed it back to them without them losing energy and slowing down.",
"In addition, the wheels will themselves not be 100% efficient, with energy at all mechanical stages being l... |
[
"Is there a temperature at which water will ignite?"
] | [
false
] | null | [
"No. Water won't ignite because it already is a product of combustion. You get water by burning hydrogen."
] | [
"Yes, like anything else. But first, the hydrogen and the oxigen in the water (H₂O) will separate forming O₂ and H₂. ",
"Take a look here:",
"https://en.wikipedia.org/wiki/Water_splitting#Thermal_decomposition_of_water"
] | [
"Everything that you interact with is defined as a chemical formula. (Think of making a cake, and the chemicals are the raw ingredients).",
"A water molecule is H2O (2 atoms of Hydrogen for every atom of Oxygen).",
"The \"recipe\" for water is:",
"2 * H2 + O2 -> 2 H2O",
"The Hydrogen is still there, but not... |
[
"Geostationary orbit vs tall tower."
] | [
false
] | Ok, I'm generally scientifically literate, but I've never quite wrapped my head around this: I'll describe the picture, can someone explain it to me in sensible physics terms. A geostationary sattelite is 35,786 km above kenya, on the equator, with my twin sat in it. He steps out of the satellite and orbits the earth. ... | [
"OK - first take a look at this: ",
"https://docs.google.com/drawings/d/1zp_HHPnwQIk0iopDHy5OBzCutwJI9tA7FJLuuFhVPfU/edit?hl=en_US",
"Anything at altitude is subject to gravity, which will draw it back towards the planet's centre of mass. First, let's look at object A. The green arrows indicate the gravitation... | [
"While you're correct, I think this is a complicated way of looking at this topic.",
"The entire tower is stationary compared to the ground, meaning that the entire tower has the same angular velocity. As you climb you maintain this angular velocity along with the tower. But to maintain a particular angular veloc... | [
"And you did an excellent job explaining that. Part of the OP's question though, was where he would get the energy to put him into that orbit. ",
"I wanted to clarify this by saying that it's the tower itself that provides this, with a frictional force on the climber.",
"Edit: This means that when you climb the... |
[
"With such a high r0, why didn't measles just burn itself out?"
] | [
false
] | I've seen speculation floating around the internet that we will get to herd immunity faster with the delta variant because it spreads so quickly, but I wonder even if that is the case, why didn't we develop enough herd immunity naturally for measles to simply burn itself out (for reference, measles has an r0 of 12-18 c... | [
"It's because of cities.",
"If a population is large enough, the influx of new susceptible individuals can keep up with the epidemic loss of susceptible to immunity and death. (In the case of measles, it's mainly immunity, which is close to life-long following infection. However, in the first half of the 20th cen... | [
"If (1-immunity rate) * r0 < 1, a disease will die out. So if r0 = 5, a greater than 80% immunity rate is required; r0 = 10, 90%. ",
"But r0 is not some fixed constant of nature; it's an average that can vary according to behaviors, like hygiene and mask-wearing, and conditions, like outdoors in the sun vs indoor... | [
"This is a fantastic answer, backed up by extensive references. This kind of answer is why I keep clicking on reddit threads."
] |
[
"Why do baked goods kept in air tight containers remain fresher when they are still exposed to air inside vs being a vacuum or alternate gas?"
] | [
false
] | Another instance may be a plastic bag which still contains a volume of air inside. Also this is not limited to baked goods but they were the best example of a food product highly impacted. | [
"A lot of times the \"freshness\" of a food depends on water. A cracker left out on a humid day will absorb a good deal of water from the air, which will leave it \"soggy\" and it'll lose its crisp texture.",
"By the same token, a lot of baked goods will actually lose water to the air. By keeping them in a baggy,... | [
"interesting points, so within that container would likely then be a localized higher or lower relative humidity respectively, not necessarily a chemical reaction or gas change..."
] | [
"On the other hand, it is good to put hot, moist breads in a bag if you intend to microwave them later."
] |
[
"What is the difference between a proton pump and a proton shuttle?"
] | [
false
] | My biochemistry textbook seems to differentiate between pumps and shuttles. However, it never really defines "shuttle" outside of "shuttles allow movement across mitochondial membranes." However, I'm fairly sure that is the definition of a proton pump. What am I missing here? | [
"I haven't heard the term shuttle used much, if at all. Perhaps you could provide some more context? Using you example, it says, \"allow movement...\" which implies to me that they are either talking about proton channels, i.e. facilitated diffusion, or antiporters, which exchange one molecule for another. Proton p... | [
"Oh, haha, it's a verb. In this case it means: to move molecules across a membrane."
] | [
"Perhaps \"shuttle\" refers to moving protons from one location in the cell to another, versus pump refers to movement across the membrane"
] |
[
"How could someone escape from a black hole? Is it even possible?"
] | [
false
] | null | [
"By definition it is impossible.",
"If light cannot escape nothing else can (since nothing can go faster than light...essentially the escape velocity for the black hole is faster than light speed). The event horizon defines the boundary where you are far enough from the singularity that at least light can escape... | [
"well, eventually the equivalent of your mass would be released into the universe through hawking radiation. so you wouldn't really be \"stuck in the black hole forever\". "
] | [
"One could not."
] |
[
"How is it possible that viruses lead to the origin of life if viruses need a living host to survive?"
] | [
false
] | According to the virus-first hypothesis, DNA-based viruses predate cellular life and contributed to its formation. There's evidence supporting this, namely that virus genomes do not contain cellular homologs. How is this possible if viruses need life to survive and replicate? I must be missing something here. Thanks! | [
"DNA does fold and do this and that, but generally tends to be more boring than RNA. RNA is really neat because it can encode genetic data AND serve as an enzyme. Ribosomes? Those have RNA. Transfer RNAs, those perform a function like a protein. ",
"Why am I saying this? A relevant hypothesis is the \"RNA wo... | [
"I am a senior biology major in college, I'm pretty familiar with the RNA world hypothesis. I'm more interested in the virus-first hypothesis, hence the specificity of the question. I do tend to think the RNA world hypothesis makes a bit more practical sense, but the virus-first idea is still a relevant idea that I... | [
"My understanding is that this theory was bolstered by giant viruses that have larger genomes and suggests that cellular life and modern viruses are descendants of a virus-like organism that could replicate itself without a host but lacked cellular features like a cell membrane (possibly a protein structure like a ... |
[
"AskScience AMA Series: We are experts here to answer your questions on shortages of laboratory testing supplies for COVID-19 and other infectious diseases. AUA!"
] | [
false
] | Since March, clinical microbiology laboratories have faced shortages of testing supplies, including SARS-CoV-2 molecular test reagents. Due to the growing demand and need for COVID-19 testing, production of supplies required to test for other infectious diseases has dwindled. This has led to a ripple effect of shortage... | [
"It takes time to develop a test for a novel agent. Although there have been rapid antigen tests for influenza and RSV for decades, we have never had one for a coronavirus, so development takes time. It also takes time to ensure the accuracy of these tests prior to them becoming widely available. Rapid molecular te... | [
"Why haven’t rapid tests become more available? Does money have something to do with it?"
] | [
"The numbers on your site showing the lack of testing equipment is stunning- 70% don't have the reagents and materials they need to test for sexually transmitted diseases? Is this COVID related or are US clinics always running this much of a material deficit? What effects does this have on getting efficient and acc... |
[
"Can a tidally locked planet still rotate on an axis if its pole is pointed at its star?"
] | [
false
] | null | [
"So if dramatically tilted planet like Uranus, was within tidally locking range of its star would it be immune to tidally locking or would its tilt be corrected so that it can be tidally locked?"
] | [
"Hm, the poles of astronomical bodies are where the axis of rotation meets their surface. For an object to be tidally locked to another, its axis of rotation must be perpendicular to its orbital plane... so the pole of a planet tidally locked to a star cannot be pointed at the star. ",
"In other words, if you dra... | [
"Part of the process of tidal locking would be rotation of the pole to a perpendicular axis."
] |
[
"Adderall works by increasing the dopamine and norepinephrine available in between synapses. Is there a way to do this naturally?"
] | [
false
] | [deleted] | [
"Simply making more won't release more. You need something to release that Dopamine or Norepinephrine (I.E. Adderall, Cocaine) I'm not sure if there is a way to release more naturally other than doing more of what normally releases it.\n Dopamine is that rewarding feeling you get after completing something you wor... | [
"Simply making more won't release more. You need something to release that Dopamine or Norepinephrine (I.E. Adderall, Cocaine) I'm not sure if there is a way to release more naturally other than doing more of what normally releases it.\n Dopamine is that rewarding feeling you get after completing something you wor... | [
"I would really like an answer to this as well."
] |
[
"Electron, Muon, Tau, why are there only 3 orders?"
] | [
false
] | There are 3 orders of electrons, 3 orders of neutrinos and 3 orders of quarks. Is this correct? Does the standard model predict 3 orders? If so why? If not, then are there any predictions regarding a 4th (or 5th etc.) Are there any theoretical constraints on further orders of particles? | [
"I'm going to give an answer from a mostly experimental point of view. Just to clear up the nomenclature, these \"orders\" are usually called \"",
"generations",
"\". Electrons, muons and taus are collectively called charged leptons. Neutrinos are the neutral leptons. They form a set of 6 particles, similar to ... | [
"Could you clarify your question? Is it more along the lines of what evidence is there that there are 3 generations of quarks and leptons, or are you asking why universe is how it is?",
"Unfortunately, the latter isn't really answerable."
] | [
"This is ridiculously in depth. Thank you for the effort."
] |
[
"Why does time seem to pass so quickly when significant events are happening or you're having fun, but time passes so slow when nothing of interest is happening?"
] | [
false
] | null | [
"I think in order to understand this we would need to know more about the biological basis of both the perception of time and of concentration. Intense concentration seems anecdotally (uh-oh) to force awareness in ways that are actually MORE evolutionarily useful. If while running away from a panther or searching f... | [
"And in retrospective it often flips. ",
"(\n which makes perfect sense: nothing happens - nothing to remember. \n (\n all as long you don't remember the feeling of \"it felt like it took forever\" \n which is sort of a flashback, making it happening again(in your head)\n )\n)\n"
] | [
"when you are so bored and nothing is happening you will start to be conscious of the time passing. kinda like (when will this end!). but when your having fun you're not thinking about time at all and so it fly's by!"
] |
[
"Do polymers made of oxygen exist?"
] | [
false
] | Do polymers exist made up of oxygen only? As in [-o-o-]n sort of thing. | [
"Not to my understanding. Based on the instability of ozone (O3), I'd venture a guess that the bonds in an 'oxygen polymer' would break really easily. ",
"While there are larger ",
"allotropes of oxygen",
", they mostly exist in pretty specific situations, and they aren't polymers in sense you're talking abou... | [
"No, the oxygen-oxygen bond is to fragile to exist as a repeat unit in a polymer structure. ",
"Organic peroxides",
" are generally not very stable. In fact ",
"benzoyl peroxide",
" is many times used as an initiator in polymerizations due the fact the O-O bond easily forms radicals. ",
"One theorize... | [
"You can make ",
"oxygen crystals",
" at low temperature. That is \"sort of like\" a polymer.",
"As the pressure of oxygen at room temperature is increased through 10 GPa (1,450,377 psi), it undergoes a dramatic phase transition to a different allotrope. Its volume decreases significantly,[6] and it changes c... |
[
"Would anti-matter react with virtual particles?"
] | [
false
] | Would anti-matter react with the virtual particles that pop in and out of existence. That would make a anti-matter storage device hard to construct right? | [
"Would anti-matter react with the virtual particles that pop in and out of existence. ",
"Probably not in the way you are thinking...",
"I think what you mean is that if I have a positron (an anti-electron) stored properly, could an electron (created from a vacuum produced e+/e- pair) then annihilate with my st... | [
"No. A virtual particle is just a way of interpreting an annoying term inside an integral."
] | [
"Yes you understood what I ment. Thanks for the explanation. You comment that the virtual pair of particles must annihilate each other to be produced in the first place is interesting. Will read up on why that is. "
] |
[
"People cannot live in Pripyat, but they live in Hiroshima and Nagasaki. What is the difference in atomic after-affects (radiation) in a bomb context versus that of a reactor meltdown context?"
] | [
false
] | [deleted] | [
"Think of the contamination like this: there is a question of ",
" contaminating material there is total, and ",
" it is on any given piece of the ground.",
"The contaminating material is primarily fission products, the left-over \"half-split\" nuclei from nuclear fission. In the case of Hiroshima and Nagasak... | [
"People cannot live (safely, long term) in the ",
"Bikini Atoll",
" either, despite that being bombed and not a reactor. Nor the neighboring ",
"Rongelap",
".",
"Reactors have a lot more fissile material in them than bombs, additionally, the massive explosion of bombs spreads the material out. So with Che... | [
"In addition to what the other people have mentioned, the timing of the radioactivity is also different. For atomic bombs, the entire bomb is vaporized and then mixed into the fallout material, so all of the different isotopes produced in the reaction end up contaminating things. Most of these elements have a half-... |
[
"Breaking down water."
] | [
false
] | My question is if we start to break down water into oxygen and hydrogen on a large scale would that ultimately lead to water disappearing altogether? I've studied the water cycle but I'm not sure how to include those gases into the cycle. | [
"If you broke down all the water into hydrogen and oxygen, then there wouldn't be any water left.",
"However, any time you burn something with hydrogen in it (or just burn hydrogen), one of the products of the reaction is water. If you put the hydrogen through a fuel cell, then you make water as well.",
"Try it... | [
"I wrote about this a few weeks ago! Check it out: ",
"http://electroncafe.wordpress.com/2011/04/11/split-that-water-part-i/"
] | [
"You're missing the point: we split H2O to O2 and H2 ",
" combine them back together and produce energy (a.k.a. burning). The byproduct of burning H2 is steam, so the water will go back to the water cycle. If we somehow store all the produced H2 and O2 and never use it, we'll effectively remove some water from th... |
[
"It seems that infectious diseases that kill too quickly never have a chance to spread. How often are people the first and only (or among very few) to die of a novel but short lived infectious disease?"
] | [
false
] | null | [
"There are several avian influenza viruses that have a high mortality rate in humans, but that transmit very poorly between humans. Viruses like H5N1, H5N6, H7N9 have killed thousands of people worldwide, each time because of a direct contact with an infected bird. ",
"However, the lack of transmission is probab... | [
"To name a few from recent memory, SARS, MERS, Ebola.",
"Ebola is a special case though. First discovered in 1976, it has a natural reservoir. It can exist in bats and apes and re-infect humans from that source. But once it does it rarely travels from human to human, as you need direct contact with bodily flui... | [
"Add rabies to the list too. 100% mortality rate once symptoms appear, but difficult to get infected by. ",
"Plus lots of natural reservoirs (bats, raccoons, etc)."
] |
[
"Do black holes really vary in size or does the collapsed point in space just vary in intensity?"
] | [
false
] | null | [
"Every amount of mass has some radius that, were it all to be compressed within the radius, it would form a black hole. This is called the Schwartzchild radius, and it's calculated by the formula r=2GM/c",
" . G is the gravitational constant, and c is the speed of light. These are both constant, so the math works... | [
"I think he was referring to the singularity itself with his question and wet her or not it can have different sizes or if it is only the event horizon being 'blown up' in different sizes (as in: the 'visible' part of a black hole).",
"\nAnd, if I am informed correctly, the singularity is basically the same every... | [
"It's also important to point out that black holes technically don't have any size, they are infinitely dense with a finite mass. The \"black hole\" part of the black hole is just the region where nothing can escape, thus appearing black. This radius will vary based on the mass of the black hole and it's angular ... |
[
"how do airplanes deal with fuel ullage? Would the engines flame out if an airliner tried to fly upside down?"
] | [
false
] | The direction of gravity will change as the plane banks and pitches up or down. So how do they make sure the fuel doesnt accumulate in a corner away from the pipes? What about those planes used to simulate 0G? Also how do they deal with the shifting center of gravity during banks as fuel sloshes outwards in one wing an... | [
"Yes it's possible. A lot of planes cannot fly upside down, including modern jet trainers, and many modern airliners. Here's an article on the famous Spitfire fighter and how its engine would die when inverted: ",
"https://www.popularmechanics.com/flight/a22201/brass-ring-spitfire-engineering-wwii/",
"Similar ... | [
"Most passenger jet aircraft have multiple tanks in the wings so fuel won't travel very far during turns as the wings point up or down. Also, before the fuel goes into the engine pylon, it will flow into a special smaller tank where fuel pumps are located which will be submerged even during prolonged turns so that ... | [
"The direction of gravity will change as the plane banks and pitches up or down.",
"The perceived gravity vector in a plane won't change as much as you might think. In a bank, the wings will still generate lift in the \"airplane-relative-up\" direction, and the occupants (and fuel) won't feel any sideways acceler... |
[
"How does sunscreen work?"
] | [
false
] | Is it as simple as physically absorbing / reflecting the sunlight? If so, how does it remain effective after being rubbed into the skin to the point that it isn't readily visible to the naked eye? | [
"Both. There are two classes of sunscreens, chemical and physical:",
"Organic sunscreen molecules, chemical sunscreen, absorb UV radiation and release it as heat or visible light. UV light excites electrons in the sunscreen which reach an excited state. As the electrons drop back to their ground state, they relea... | [
"Thanks!"
] | [
"http://en.wikipedia.org/wiki/Sunscreen",
" scrolldown, see illustrative pic"
] |
[
"Does quantum theory depend on the uniformity of nature?"
] | [
false
] | 'Uniformity of nature' as in the principle that the future will resemble the past, in that when sufficiently similar situations recur, similar effects follow. So "induction" I guess. | [
"in that when sufficiently similar situations recur",
"Determinism? Most models of quantum mechanics rule out determinism and replace it with stochasticism (ie: \"true randomness\" exists in some sense)"
] | [
"So uniformity of nature doesn't deal with quantum mechanics? Are they on some other level? "
] | [
"All of science depends, more or less, on the principle of uniformity."
] |
[
"If I built a lightning rod high in the air with a giant coil between the rod and the ground, would lightning pass through it and therefore create a giant fluctuating magnetic field for a few seconds?"
] | [
false
] | Assuming that the material can withstand the current involved, of course. In theory, if there is no electricity flowing through the coil before the strike, then the top of the lightning rod should be at ground voltage, right? So, being in close proximity to the sky, and if lightning takes the path of least resistance, ... | [
"If you get a lightning strike, you will get a big magnetic pulse from the coil. It would have a fairly interesting (and varied) fluctuation. The main discharge of lightning typically has multiple \"strokes\" separated by 10s of milliseconds. So you wouldn't get one big magnetic pulse, you'd get several smaller on... | [
"If we were talking about a heavy duty coil, how the impedance of the coil effect this. With a nearly instantaneous (or several nearly instantaneous) discharge, wouldn't we get a pretty sizable back EMF? "
] | [
"I assume so, yes. You'd get a big dI/dt which would drive a big dH/dt which would in turn create a significant dE/dt & resulting dI/dt in the opposing direction. So you'd probably need a good simulation to figure out what the potential at the tip would be after the first stroke. It might be raised significantly an... |
[
"If the planet Mercury's day is twice the length of its year, what path does the sun take through the Mercurian sky?"
] | [
false
] | Does the high eccentricity of its orbit matter at all? | [
"I wouldn't say that it's same as Earth, just longer. There would be all kinds of interesting effects.",
"First it's good to know about the different kinds of days there are. On Earth the different types of day are almost the same length, varying only by some minutes. But on Mercury they are vastly different. Fir... | [
"This will probably help",
". It simulates what the sun would look like from Mercury's surface."
] | [
"That is freakin' AWESOME!"
] |
[
"How do we tell apart matter and antimatter?"
] | [
false
] | They both have mass, reflect light, have charges, etc. right? So, while electrons and positrons have opposite charges, complete anti-atoms would have 0 charge just like normal matter. Since they have identical charge, probably reflect light the same way, etc. how do we tell them apart? Perhaps there isn't really any le... | [
"Taste it. If it tastes like a burst of gamma-rays, it's antimatter.",
"Seriously though, if there were entire planet's, solar systems, galaxies, or gas clouds made of antimatter then they would interact with the interstellar or intergalactic medium. These annihilations would produce gamma rays we could detect. W... | [
"Anti-matter annihilates when it comes into contact with matter.",
"Essentially if your anti water touched some water you'd end up with gamma rays and no water. This would be the end-all test which would identify the two apart. Also when you measure objects in the sky you never really see widespread high energy e... | [
"So we're basically assuming that there is little antimatter basing on the fact that there are too few effects of matter-antimatter collisions present?"
] |
[
"Chemists: How long does cologne keep before changing scent? Are there any fragrances that spoil faster/slower than others?"
] | [
false
] | [deleted] | [
"More curious than concerned. I took a bunch of organic chemistry, so was looking for a slightly more detailed answer..."
] | [
"More curious than concerned. I took a bunch of organic chemistry, so was looking for a slightly more detailed answer..."
] | [
"Why the hell would you even think he'd be concerned. And what kind of shitty answer is that?"
] |
[
"Can someone decode this paper for me? How can an occupation of being a mathematician correlate to higher birth defects in the baby?"
] | [
false
] | Is it just one of those correlation != causation things? | [
"The study seems pretty underpowered. For mathematicians, in 3 out of the 5 defect categories listed, they observed no significant association between the defect and paternal occupation of mathematician. For the other 2 defects, Anorectal atresia/stenosis and Coarctation of the aorta, the association is barely sign... | [
"SPECULATION: paternal age is a known correlational factor for higher birth defects (older is worse). Perhaps some of those occupations relate to people becoming parents at older ages?"
] | [
"Many of these jobs that are here are those that are exposed to some form of chemical. Various solvents used in industries can cause ",
"birth defects",
".",
"I will say that many of those jobs seem very far removed from such chemicals...mathematicians included. However, the paper does not really attempt to... |
[
"If I microwave two pieces of food, should I double the cooking time? What's the relationship?"
] | [
false
] | Also, how does density, surface area, and mass affect the relationship with total microwave time? I've always been curious about this. Thanks in advance. edit: sorry, I mean "two identical pieces of food" | [
"Microwaves are tuned to the ",
"quantized rotational absorbance",
" of water, so the amount of energy absorbed is related to the amount of water. The microwave wil put out a specific wattage and this is the maximum amount of energy it can output, if the max is being absorbed, then you would need 2X the time t... | [
"I was bored and worried what if you wanted to make 13 rolls? Or PI/2 rolls? So I curve fit it fit it for you just in case you ever run into the situation and need to figure it out quickly.",
"PreFlipTime=5+((10/3)Rolls)\nPostFlipTime=(3*Rolls)-6",
"Or",
"PostFlipTime=(0.9*PreFlipTime)-10.5"
] | [
"No, the formulas are consistent with you :)"
] |
[
"How much do tidal forces affect volcanic and magmatic activity?"
] | [
false
] | For anything from Hawaii to Yellowstone, or even for similar things like oil deposits, how much does the tidal force from the moon affect them? | [
"As ",
"/u/Ocean-Chemist",
" stated, there is no consensus as to whether tidal forces are relevant with respect to volcanic eruptions on Earth. Personally I suspect in my professionnal opinion that if they are relevant at all, they aren't relevant very much.",
"HOWEVER, there is no controversy whatsoever abou... | [
"Does the Moon help mix the mantel? "
] | [
"My understanding is that tidal triggering of earthquakes and eruptive activity is a somewhat of a controversial topic. ",
"Tolstoy (2015)",
" found a relationship between seafloor eruptions at mid-ocean ridges and neap tides (among other findings!) - and cites a bunch of other research on tidal triggering of v... |
[
"Physics is the same no matter what time direction you are going in, is there an exception?"
] | [
false
] | here is the article I read. ( ) | [
"T-symmetry",
" is when physics is unaffected by the direction of time. T-violation is when it's different. ",
"The most familiar, everyday example of T-violation is ",
"entropy",
" (a measure of the 'disorder' of a thermodynamic system), which must always increase as per ",
"the 2nd law of thermodynamic... | [
"It's a mistake to connect increase in entropy to CPT. If you set up a random system with low entropy, it will increase in both directions of time. I don't think any physicists would seriously suggest entropy would magically decrease in one direction because of CP asymmetry. "
] | [
"Is the second law of thermodynamics invariant under CPT symmetry?"
] |
[
"Do multidimensional (more than 3D) mathematics and physics have practical use that we can face in everyday life?"
] | [
false
] | null | [
"Yes yes and more yes!",
"The mathematics used in multidimensions is really the same thing as saying that the problem is multivariable. In fact almost any real world problem you solve will be more than 3 variables (dimensions). In fact describing one of the the simplest possible situtations, a single point partic... | [
"It's curious how we imagine multidimensional problems as complex graphs (like 3d projection of tessaract), trying to \"break\" our standard 3d perception.\nBut you are completely right - math is all about multivariable problems and often there is no need to imagine it in graphical way.\nNow I understand naivety of... | [
"One of the most fascinating aspects of mathematics I've encountered in my engineering studies is non-dimensionalization of partial differential equations. A complex relationship of six or more variables in a brutal PDE, with some clever manipulation of dimensioned quantities can become a simple ordinary differenti... |
[
"Do the Alpha Centauri stars and the Sun originate from the same supernova?"
] | [
false
] | So I was thinking of how new stars are born from the remains of dead stars, or nebula, that form accretion disks thanks to gravity. Since nebulas are pretty big and can stretch for lightyears, is it plausible that the matter found in the accretion disks that formed our Sun and the stars of Alpha Centauri, comes from th... | [
"No, stars can't form from supernova remnants and planetary nebulae themselves, but from gas clouds (cold molecular clouds in particular) that got enriched by material from those stellar remnants. ",
"The sun is an intermediate population I star, which means, the gas cloud it had formed from was enriched with met... | [
"Supernova explosions can trigger a star formation event in a molecular cloud close to the shockwave, but supernovae themselves contribute very little to the mass of a newly formed star. They do contribute the bulk of the \"metals\" that form the solar system that results from the collapse of the cloud, metals mean... | [
"https://en.wikipedia.org/wiki/HD_162826",
"It's quite difficult to discover stellar \"siblings.\" This Wikipage explains why."
] |
[
"Does Reading Prevent Cognitive Decline?"
] | [
false
] | Hello, if you are a regular reader, is there a chance that you can prevent developing Alzheimer's or dementia? I just want to know if reading a book can help your brain become sharper when remembering things as you grow old. I've researched that reading is like exercising for your body. For people who are doctors or ne... | [
"it definitely does",
". I'm not sure how much causality has been established though, it could very well be that people less likely to experience cognitive decline are also people who read books.",
"That said, there's also the fact that people who lose their hearing often rapidly decline in cognitive ability. C... | [
"Also, cognitive decline may result in a reduced preference for and enjoyment of reading."
] | [
"This study suggests",
" reading is protective of cognitive function in later life. Frequent reading activities were associated with a reduced risk of cognitive decline for older adults at all levels of education in the long term.",
"From the article:",
"Participants:",
"A representative sample of 1,962 Tai... |
[
"How do pets view TV?"
] | [
false
] | I have always wondered if they don't understand the moving image on the screen or if they know there are humans projected on a screen. Do they think we are crazy for staring at it for hours? | [
"We talked about this in one of my neuroscience classes. They see things at different frame rates than people do, so it looks like a series of odd pictures. They probably think we see the same thing. But some dogs like those pictures (e.g., my sister's dog barks at any horses/dogs on tv)",
"EDIT: Add on: There ar... | [
"iirc, the flicker fusion threshold of dogs (and likely cats) is significantly higher than humans (by an order of magnitude). i think that, however, modern hdtvs at 120hz and 240hz exceed even this",
"however, even though they can see fluid motion on tvs, the question remains whether their perception of what's oc... | [
"Apparently octopuses can only see HD"
] |
[
"If the COVID vaccine teaches our immune system to attack COVID’s spike protein that binds to ACE2, won’t the immune system also attack angiotensin II which was originally meant to bind to ACE2?"
] | [
false
] | null | [
"Antibodies aren’t mirror images of the things they target, so even antibodies that target the RBS won’t target angiotensin. ",
"Many if not all viral vaccines target the receptor binding region of the virus, and overlapping immunity to the receptor is simply not a problem."
] | [
"Antibodies are very specific to their antigen: just because angiotensin binds there does not mean the vaccine will elicit a response against it. Antigens are determined by amino acid sequence AND 3d structure of the protein. There would need to be a very high similarity in sequence between two proteins to be targe... | [
"I already answered this question a few days ago in this ",
"/r/askscience",
" post: ",
"https://old.reddit.com/r/askscience/comments/k4ndl7/how_do_we_know_that_covid19_vaccines_wont_teach/"
] |
[
"How is the immune system involved with acne?"
] | [
false
] | So everyone I get sick, my acne goes away. Is this because my immune system is focused on better things? I’m confused how this works… | [
"I don't think that's entirely correct. Yes, your immune system directs the inflammatory response. However, acne itself would not occur in the absence of bacterial overgrowth. ",
"As you know, a whitehead is a clogged pore, and doesnt always have painful inflammation. A blackhead has the clog so superficial t... | [
"Again, there hardly seems to be a consistent outcome. Some people seem to go into overdrive and \"beat\" the acne while others seem to trigger the inflammatory response that turns whiteheads into pustules."
] | [
"Thanks for the response! \nI thought your immune system is what caused acne in the end. Because your immune systems response to a clogged pore is to make it red and inflamed in hopes of clearing it out?"
] |
[
"Can we (humans or animals in general) obtain hydration from the water vapor in the air? Do I need to drink less on humid days than I do on dry ones?"
] | [
false
] | Follow-up: Assuming same volume of input liquid water and work performed under lab conditions, etc. "All things being equal" will a man working in arid conditions be more dehydrated than a man working in humid conditions? What's happening either way? Does the water vapor condense in our systems back into a liquid? I pr... | [
"Air within the lungs that participates in gas exchange is 100% humidity and body temperature. This means that since the air you're breathing actually has more water content than outside air unless that air is 37C and 100% humidity. Because of this we cannot obtain water from the air.",
"I think it's fair to sa... | [
"It's not typically taught in a biology class.",
"A lot of anatomy courses leave it out too."
] | [
"Fascinating! Thank you for that. I can't remember if I may have once known this from Bio classes or not. "
] |
[
"Ask Anything Wednesday - Economics, Political Science, Linguistics, Anthropology"
] | [
false
] | Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical post? No question is too big or small for AAW. In this thread you can ask any science-related question! ... | [
"I recall reading somewhere that the language you speak alters your perception. Have there been studies to find out to what degree it might do this?",
"i.e. We have a lot of sentences that start with \"I\". Does that effect how we think towards being more interested in our selves? "
] | [
"Are there any organizations actively working towards artificial general intelligence?"
] | [
"Yes indeed! ",
"A lot of corporations, organizations, and universities have been seriously working to achieve General AI since the late 1950's. ",
"This ranges from tech companies like IBM (evolving Watson to do more and more, as well as even inventing special circuits and processors to do specific AI and gene... |
[
"Can sound travel faster than light in a dense enough medium ?"
] | [
false
] | Considering that sound travels faster in denser mediums, can sound go faster than light if it travels in a dense enough medium ? How dense would it have to be ? Does anything that dense exist ? | [
"The sound speed in a very dense medium, like the core of a neutron star, could in theory be almost as large as the speed of light in vacuum. Sound waves cannot be faster than the speed of light in vacuum, according to relativity, otherwise they would violate causality. Physically that would mean that you would be ... | [
"Sound is just a wave of moving particles. You can think of it almost like a chain of dominoes. It propagates when one particle shifts into another and transfers momentum. ",
"The speed of sound is limited by how fast those particles can move, and that is limited by the speed of light."
] | [
"The speed of sound cannot exceed the speed of light. In fact, it may be the case that the speed of sound ",
"cannot exceed 57% the speed of light",
", which is the speed that sound propagates through a hyper-relativistic gas. However, inside neutron stars there may be sound waves faster than this."
] |
[
"Why does Mars have a slightly larger axial tilt than Earth without similar evidence of a proto-planet impact?"
] | [
false
] | I learnt that Earth has its axial tilt because of an impact with a proto-planet that also created the moon. While Mars also has two moons, they are 10 and 10 times smaller than our own moon. Why doesn't Mars posses a similarly proportional sized moon? | [
"It does have an enormous basin possibly the remnant of a large impact. It is thought that several moons were formed, but the largest ones eventually recollided with the planet. Follow this link for one theory",
"https://www.space.com/33335-huge-moons-may-have-hit-mars.html"
] | [
"While its true that most observations about axial tilt in our solar system are the product of planetary collisions, there are some that can't be adequately explained that way (Uranus). People have come up with other mechanisms that have been shown in simulations to cause axial miss-alignment over longer periods of... | [
"Yup, it would be one of the many challenges of colonising Mars - protecting from solar radiation. "
] |
[
"Is the human race showing any signs of natural selection and evolution?"
] | [
false
] | I was reading this news: and it says that Asian Elephants are being born tusk-less as a result of severe poaching. this occurred in the short time-span of 100years or so. So, is there anything that we have observed? are we smarter than our ancestors? are we physically weaker too? | [
"This is an example my Physical Anthropology 101 professor used: the existence of Tay-Sachs Disease in the Ashkenazim Jewish community. Of course, Tuberculosis was a problem in larger cities throughout the medieval period. At the same time, Jews were generally segregated into their own quarter of the city and due... | [
"That would be an example of heterozygote advantage. Malaria resistance from a single copy of the sickle cell gene is another example; if you're homozygous (two copies of the allele) for sickle cell, you get sickle cell disease. If you're homozygous for normal blood cells, you're vulnerable to malaria. But, if you'... | [
"Sickel-cell anemia",
" is ",
" the same: Homozygous is deadly, heterozygous reduces the severity of malaria. Their ",
"source",
" seems to have disappeared, but that Wikipedia page claims that in some areas, as many as 45% of people are heterozygous for it.",
"Edit: And ep0k beat me to it by 5 hours, I p... |
[
"Do dogs of one breed prefer to be with their own breed over others or are they all just dogs to them?"
] | [
false
] | Also other animals that have breeds, like cats, sheep, cattle etc. | [
"Please no more anecdotes about your dogs. Please stick to scientific information gleaned from studies. ",
"Thanks."
] | [
"I don't know what they ",
", but I've seen research that indicates that different breeds communicate using different signals. ",
"For example, from \"Paedomorphosis affects agonistic visual signals of domestic dogs\" by Goodwin, Bradshaw, and Wickens, ",
"Visual communication between domestic dogs (revie... | [
"breeds of dogs that have retained a wolf-like appearance, in many modern breeds most or all of the ancestral structures used for signalling (e.g. the muzzle, the area around the eyes, the ears, the tail) have been substantially modified by selective breeding.",
"Sounds like it has more to do with the morphology ... |
[
"Why can't we supress sound by sending opposite waves? (or can we)"
] | [
false
] | This is something I've been having around my mind since i was a kid. When I learned that sound was just momentary compressions of air, I thought if I could capture somehow what the exact sound waves coming to me were like, and , pressure of air (waves) would neutralize each other, thus killing that sound. Is that possi... | [
"Yes, we can!",
"Although it's not perfect, because the shape of sound waves is complex and becomes distorted by differences in air density, reflects off surfaces, etc... so the hard part is making the opposite waveform exactly opposite.",
"If you have a stereo system with separate speakers that use plain old j... | [
"Is that possible? If not, why not?",
"Yes and no.",
"What you are describing is called ",
"active noise cancellation",
" and is the way devices like noise canceling headphones work. Set up a microphone in one location, use the sound at that location to predict the sound at another location an instant later... | [
"I'm a DJ, and when in setting up my speakers in a room, depending on the room arrangement, my two subwoofers have 'hot spots' within the room where they are louder, and others where it's not so loud. It's the same idea, due to the sound waves bouncing differently off the walls, and at different angles causing the ... |
[
"According to Special Relativity the mass of an object increases as its speed increases, does this mean that if I brought a highly accurate weighing scale on a aircraft I would appear heavier than on ground?"
] | [
false
] | Disregarding factors that would probably disturb the experiment (I am no scientist by a long shot but): Centrifugal force, reduced gravitational force due to height, "shaking", and probably some other things I have never even heard of. | [
"Not exactly. \"Mass\" itself doesn't increase once you increase velocity. The faster an object moves, the harder it is to accelerate it, though. This is only due to the properties of special relativity, an in order to interpret that in a classical context, objects are often said to have a \"relativistic mass\", wh... | [
"Could you elaborate on the difference between \"harder to accelerate\" and \"mass increase\".",
"So if mass remains unchanged, does f=ma no longer apply?"
] | [
"I'm kind of surprised that none of the answers so far have pointed out that your question is ill-posed. Special relativity concerns itself only with inertial frames of reference, which means that you cannot have acceleration or gravity (though these are actually the same thing under Einstein's principle of equival... |
[
"If people had a speech disorder growing up can they retain that learning disability when they learn a new language?"
] | [
false
] | I was wondering if this is common because I find myself suffering from a speech disorder I had when I was younger and resolved it, as I now try to learn French. | [
"It depends on the disorder. Aphasia is pretty much something you're stuck with regardless of language as it results from damage to the parts of your brain that contribute to language production (Broca's and Wernicke's areas, for example). Stuttering is more behavioral and can be untrained but might need to be re-u... | [
"Speaking totally anecdotally, yes. I have a minor impediment (I hope this is what you mean) where I don't fully pronounce R's. Spanish's rolling R's are all but impossible, even though my English R's are nearly normal. "
] | [
"You can correct that fairly simply. A speech therapist can show how to articulate the R's. The fact that your English R's are normal is precisely because they're articulated in a different way than our Latino R's. 4 op: I can also confirm that you can have a minor speech disorder using one language, and speak norm... |
[
"I read that elephants are now being born without tusks because of poaching, is this how you can control evolution? If human beings had their pinkies chopped off, would that result in humans eventually being born without a pinky finger?"
] | [
false
] | null | [
"It's not that elephants who have tusks removed give birth to elephants with no tusks. Rather elephants with smaller tusks are less likely to be poached. So they breed. Their children with large tusks get poached. Their children with even smaller tusks are more likely to survive. And on and on. It's the same with h... | [
"But elephants are now being born without tusks completely."
] | [
"Indeed. Eventually, tusks become smaller through selection until they are not noticeable. Some elephants will still be born with smallish tusks, others with no visible tusks. If poaching stops, perhaps large tusks will again become signifiers of health or strength and larger tusks will be selected for and tusk len... |
[
"What is going on in the human brain when someone has multiple personalities?"
] | [
false
] | When the person switches to a different personality why does the person not remember anything the other personality is doing? | [
"First of all, ",
" is really, ",
" poorly studied. Knowledge about it is based largely on case studies, and there's a relative paucity of neuroimaging studies in the area.",
"The notion that DID is even a distinct personality disorder is heavily contested, as people diagnosed with it tend to have extremely h... | [
"Many strange phenomena have been both reported and studied in DID. Sometimes one personality will be left handed, even though the primary/original/whatever personality is right handed. When studied, that personality will indeed show a preference for using the left hand and perform better with the left hand than th... | [
"In clinical settings, \"multiple personalities\" is called Dissociative Identity Disorder. As mentioned in other comments, DID is quite controversial and poorly studied. The few brain imaging studies on DID have pointed to ",
"decreased volume",
" in brain regions such as the amygdala and hippocampus, but the ... |
[
"When light beams create destructive interference, where do the photons go?"
] | [
false
] | Prompted by (where I kept hoping someone with a background with optics would show up to help) asking about the possibility of "light cancelling filters" - I know how sound can have destructive interference, since "sound" is actually the effect of compression and rarification of a medium. When "sound" waves are subject ... | [
"when two beams of light destructively interfere, they only do so in ",
" location. There will always be other locations in the optical system where there is constructive interference which contain the seemingly missing energy. The entire system still contains the same amount of energy when you take all interfe... | [
"So you're saying you can't have an \"active light canceller\" in the same way you can have active noise cancellation? ",
"Active noise cancellation works with destructive interference which has the effect of nullifying the compression and rarification waves in the medium. ",
"With two beams of light in a vacuu... | [
"So you're saying you can't have an \"active light canceller\" in the same way you can have active noise cancellation? ",
"interference is a behavior of waves, regardless of the ",
" of wave, so what I said above is true of sound waves as well. Noise cancelling headphones are designed to be noise cancelling wh... |
[
"Is the earth getting lighter or heavier?"
] | [
false
] | I'm very interested to know whether the earth is getting heavier or lighter every year. I would assume that such things as cosmic dust, meteors, etc. make it heavier. and things like space probes / mars rovers, evaporation of gasses in the atmosphere, etc. would make the earth lighter. And is the earth getting heavier ... | [
"Yes, ",
"Estimates for the mass of material that falls on Earth each year range from 37,000-78,000 tons. Most of this mass would come from dust-sized particles."
] | [
"well Earth is Slowing its rotation as a result of the tidal drag from the moon. This is the Primary method of slowing our rotation. ",
"the rate we are increasing our diameter is so very very very slow that I doubt the acquisition of a few tens of thousands of tons of material a year is measurable on the rate of... | [
"does it absorb at a larger rate than the rate we send items into outer space? "
] |
[
"Question about muscle fatigue."
] | [
false
] | Hi, and sorry for my english. So, my question is this: does 'isolated' muscle fatigue affecting other muscle performance? Let me expand on this. Imagine that i can do 15 bicep curls before i can't do them anymore in one set. Now, let's say i will do something completely isolated from biceps, like a calf raise in an exe... | [
"The first main source of energy comes from muscle glycogen stores. Thsee depleted very rapidly, prompting a switch to oxidation pathways. When your muscle fatigues (using your rep range of.15) it is because the glycogen stores within the muscle.have been depleted. At this stage there should be no detriment to perf... | [
"That wasn't really helpful, sorry. I got into the argument about it, my argumentation was that if you ran a marathon you obviosly will not be able to do same amout of reps because you will feel exausted(and he agreed to it), but his responce to that was that running is a exercies that uses all of your muscles (eve... | [
"Those are two different energy systems. Resistance training uses primarily carbohydrates for energy, whereas a marathon uses primarily fat. I'm going to try to simplify the physiology aspect by summarizing to the point that the body tries to conserve glucose, and that glucose is the limiting factor to an enduran... |
[
"How do photons carry \"information\" from a point in the universe to our brains that becomes an image?"
] | [
false
] | If everything we see in the world, and more specifically, the photons travelling from distant planets/stars is how we perceive it after the time it's taken the photons to travel to our eyes, does that mean the photons carry "information" of the image that our brain interprets? The way I'm thinking about it is, if there... | [
"A photon carries information by its direction relative to your eye by where it hits your retina and color by the wave length of the light. And of course also intensity, but that's an accumulative effect by the number of photons.",
"You're always seeing the past. The further away the source is the further into th... | [
"I'm having a hard to time trying to formally express what the way I'm thinking about this. ",
"So let's say the particles that make up the moon; It's not the actual particles that make up the moon that are travelling to my eye, generating my visualization of the moon. It's the photons that are traveling back fro... | [
"you're mixing levels of information here.",
"an image is formed on the retina - it is made up of photons. this image carries ",
" information, but less than you think. it is highly ambiguous about its source, if you want to think about visual information in terms of the image being \"about something\". in this... |
[
"Where did energy originate from?"
] | [
false
] | [deleted] | [
"This video is about pretty much exactly what you are asking for, watch it!",
" "
] | [
"Thank you kind sir/lady of science!"
] | [
"Excellent question, great answer. "
] |
[
"Question about drug half life."
] | [
false
] | If a drug is stated as having a half life of 35 hours is there a degree of error that you can assume? i.e different people metabolising at different rates and other factors. Is there a formula for working out amounts of the drug in the body after a given time? | [
"Good question. The distribution and metabolism of drugs is called \"pharmacokinetics.\" It's very important (in terms of safety and efficacy) to know how long the drug persists in the body and how it is metabolized, so research into this is part of the reason why pharmaceuticals are expensive to develop!",
"Huma... | [
"There are all sorts of models for drug levels in the body, depending on all sorts of factors--how it is metabolized, if it passes through the kidneys, etc. In many cases, the models for calculating drug levels in the blood will involve using a system of differential equations, where each organ involved in the dru... | [
"Depends on the drug, what you mean by continuous usage, and so on. If you let me know the drug, I can do a literature search, but a pharmacologist or a doctor would know best--pharmacokinetics is extremely complicated (not even the best drug chemist in the world could answer this question just by knowing the chemi... |
[
"Are +∞ and -∞ the same point on the number line?"
] | [
false
] | [deleted] | [
"You are correct, this is the ",
"Projectively Extended Real Line",
" and it looks like a circle. But there are other ways to do it, like the ",
"Extended Real Line",
", which just caps both ends of the real line with two points that we call -∞ and +∞. You can get the projective real line from the extended ... | [
"I think an worthy clarification here is that there exist multiple number lines. The answer to OPs question is Yes on the Projectively Extended Number Line, No on the Extended Number Line, and isn't well posed on the Real Number Line because ∞ is not on that number line."
] | [
"Wow, a great read! Thank you."
] |
[
"Is it possible to travel AT the speed of light?"
] | [
false
] | From what I know, it is not possible to travel FTL but I am having trouble finding anything that says that we can/can't travel at the speed of light. Is it possible to do so? If not than are speeds near LS possible? Such as 99.99% the speed of light. | [
"It is not possible for anything with mass to travel at exactly the speed of light. Speeds very close to the speed of light are entirely possible, however, and massive particles reach speeds greater than 99.99% of the speed of light (typically written .9999c) in particle accelerators every day."
] | [
"You do not view the speed limit ",
" in the correct way. ",
" is, with respect to (for example) force required to accelerate to it, an asymptote. The limit of this force is infinite as you approach ",
"!",
"You will be able to keep accelerating just as nornal, but your deltaV will get smaller and smaller a... | [
"You do not view the speed limit ",
" in the correct way. ",
" is, with respect to (for example) force required to accelerate to it, an asymptote. The limit of this force is infinite as you approach ",
"!",
"You will be able to keep accelerating just as nornal, but your deltaV will get smaller and smaller a... |
[
"Conservation of Information in Quantum Mechanics"
] | [
false
] | Now, I know that I don't have a great understanding of Quantum Mechanics, but I've had a few Physics courses in college going through introductory Modern Physics, but something that's always puzzled me is the idea tossed around that Quantum Mechanics implies a random universe. Now, my understanding is that even in Quan... | [
"We currently don't know how quantum mechanics really works. As far as we can tell, it's truly random, but it's possible that there are hidden variables which would tell us what will happen if we could see them. Until we are able to learn more either way, we simply don't know whether the universe is deterministic o... | [
"if I'm not mistaken, when we talk about conservation of information, we talk about the conservation of the ",
" of information. To use a completely ",
" analogy, it's like a hard drive filled with different kinds of files. It doesn't matter what the data on the drive say, it just matters that you can't put mor... | [
"doesn't that mean that given complete knowledge of the state of the world at any given time we can predict what the state of the world at any given time in the past or future will be",
"To add onto what shavera said, what you're talking about here is determinism, not conservation of information, and these are tw... |
[
"Why and how did the Earth form so that only the huge land mass of Pangaea protruded from the ocean?"
] | [
false
] | [deleted] | [
"Earth's tectonic plates float and move around on the mantle. The last time the continental plates happenned to to drift together to form a super-continent is called Pangaea. However, Pangaea was not the first (or for that matter it won't be the last) time that all the Earth's continents were together. The continen... | [
"How did scientists look at the earth we have today and manage to deduce so many previous supercontinents with enough accuracy to name them? What evidence do they look for?"
] | [
"Naming them doesn't require accuracy, just imagination. To answer your question properly though, the main source of information for reconstructing positions of past landmasses is palaeomagnetism. This is the same sort of geophysics which was used to prove sea-floor spreading and energise the whole plate tectonic r... |
[
"Is it possible to create an \"icethrower\"? (Like a flamethrower but cold) Or are powers like that of Iceman impossible?"
] | [
false
] | null | [
"As opposed to heating radiation (infrared, for example) you cannot emit cooling radiation, which means that the only way to cool something is to throw a cold substance at it -- preferably one that goes through a phase change like liquid nitrogen or \"dry ice\" (frozen carbon dioxide) -- or to encase it in/surround... | [
"Well, sure. I mean, the basic principles of a flamethrower isn't that you're shooting 'heat', it's that you're firing flammable fluid that's ignited as it exits the weapon. Similarly, you could construct a weapon that fires a particulated cold substance, like liquid nitrogen or what have you. The problem, of cours... | [
"without the aid of a freezing chemical like liquid nitrogen.",
"Well, since you're comparing the concept to a flamethrower, remember that flamethrowers ",
" work by shooting a burning fluid (usually a liquid fuel in military flamethrowers, though civilian versions for de-icing and such commonly use propane)."
... |
[
"Is raw cookie dough actually dangerous?"
] | [
false
] | Ok, I understand the raw ingredients being unsafe to eat, but c'mon, who doesn't love buying tubes of cookie dough and going to town? Is it actually really harmful? Or is it just a kind of disclaimer incase the slim chance of getting harmed from it happens? | [
"it's a disclaimer of sorts. One of the ingredients of cookie dough as you undoubtedly know is eggs. eggs are a known carrier of salmonella bacteria and you could contract a salmonella infection from a raw egg. cooking eggs kills the bacteria and so cooking the cookie dough effectively eliminates the chances of you... | [
"Wow. That means if I eat a raw egg every day of my life, and I'm lucky enough to live 80 years, I will eat one contaminated egg in my lifetime.",
"I'll play those odds. Pass the cookie dough.",
"maths:\n2.3 million contaminated eggs in 69 billion total eggs = 1 in 30,000 eggs is contaminated. There are almost ... | [
"From Wikipedia:",
"A study by the U.S. Department of Agriculture in 2002 (Risk Analysis April 2002 22(2):203-18) suggests the problem is not as prevalent as once thought. It showed that of the 69 billion eggs produced annually, only 2.3 million are contaminated with Salmonella—equivalent to just one in every 30,... |
[
"How does a spinning object “know” it’s spinning?"
] | [
false
] | I’m confused about rotating frames of reference. I get that there is no universal frame of reference and thus no universal definition of what is moving and what is not. However, acceleration is universal but requires energy. So I’m confused about a rotating frame of reference. If you have a wheel spinning in space how ... | [
"The laws of physics have to be modified in non-inertial frames, and that leads to experimentally observable differences between inertial and non-inertial frames.",
"An inertial frame is one in which Newton's first law holds (an object at rest with remain at rest, and an object in motion will remain in motion wit... | [
"It depends on how precisely you're able to measure things. When you get up and walk around, you don't feel a Coriolis force acting on you. And if you were to stand at the equator and at one of the poles, you wouldn't be able to sense the tiny difference in your effective weight due to the centrifugal force. But wi... | [
"but how would you attempt to find the most \"stationary\" object in the Universe.",
"Relativity says that that doesn't exist."
] |
[
"Is the total number of possible Calabi Yau space's expected to be finite?"
] | [
false
] | In my (armchair physicist style) education about string theory, I've heard that the number of possible Calabi Yau manifolds quickly grew to an unmanageable quantity. Mathematically speaking is it possible that there is an infinite amount of them? Or do we have reason to believe that there is a limited set of possible s... | [
"All tori are one (complex) dimensional Calabi-Yau manifolds, and there are infinitely many tori, so there are infinitely many Calabi-Yau manifolds. This is from ",
"wiki",
". ",
"I think the frear is over the number of ",
" or ",
" of Calabi-Yau manifolds, and I don't know the answer to that question."
] | [
"To my understanding, they are the curled up shapes that the dimensions themselves take. The dimensions being the degrees of freedom in which the strings vibrate. ",
"It gets very hard to describe what a dimension IS exactly, as it's not like little blobs of something. The extra dimensions aren't placed IN our un... | [
"To expand your answer. These extra dimensions are presumabley no different then x, y, or z, or, left or right. There are just additional ones. We experience them somewhat like ants do in a 2-dimensional ant farm, except the glass panes are only separated by the planck length, they do not crush us, and there may b... |
[
"Why does a pressure decrease in a liquid phase (propellor in water) cause vapour to form, while a pressure decrease in a gaseous phase (propellor in air) sometimes cause water droplets/ice to form?"
] | [
false
] | In an attempt to answer 's question in post, I ran into what seems to be a contradiction. I can explain why a decrease in pressure under water causes cavitation, and (with some help from google, my thermodynamics has apparently become a bit rusty) I can explain why a decrease in pressure in air causes a temperature dro... | [
"This is a great question.",
"I think part of the cause of your confusion is that in the case of the water cavitation problem, you're talking about basically pure water, so the phase diagram of water tells you what you need to know - at constant temperature, a pressure drop gets you water vapor.",
"When a fluid... | [
"I think it can be thought of this way: a pressure decrease in a liquid allows the liquid to boil/vaporize. The part you're having trouble with seems to be water/ice precipitating from depressurized air. The water vapor condenses when it gets below the \"triple point,\" right? So as the air pressure drops, I'd imag... | [
"The air expands and therefore cools as a result of the lower pressure. Liquid water doesn't. That's what the difference is. So the expansion of the air follows a line on that phase diagram that goes down and to the left (but nearly horizontally - look at the scale of the y-axis), but the expansion of the water ... |
[
"How can matter enter a black hole?"
] | [
false
] | [deleted] | [
"If we drop a clock in a black hole and observe it from distance, the time shown on the clock would slow down until it reaches the horizon, where it would freeze. ",
"This part is correct. The object would then gradually get redshifted until it's no longer visible and eventually detectable. ",
"So from the cloc... | [
"Also, the infalling observer sees only a finite history of the universe, contrary to the very incorrect but popular \"they see the entire history of the universe sped up in an instant\"."
] | [
"Time is relative, every observer experience time to be flowing at a normal rate for themselves, but will see other objects as going faster or slower through time depending on their velocity (special relativity) or acceleration (general relativity) "
] |
[
"If the earth travels at roughly 30 K/ph, or just above mach 88, why doesn’t it seem to make a sound?"
] | [
false
] | Exactly as the title implies, if the earth is traveling at mach 88, why isn’t everything blown out of the atmosphere by a massive sonic boom? Why are we able to accurately launch objects into and out of orbit? I get that sound doesn’t travel in a vacuum, but why isn’t sound generated in atmosphere by this movement? As ... | [
"It's not technically correct to say that the earth travels \"at 30 km/s\" because speed isn't an absolute quantity. Speed is always relative to something else. When you say a car drives at 100km/h, really we mean that the car moves at 100km/h compared to the ground. If you're driving in your car on the motorway go... | [
"Nebulae are still incredibly low density structures - they will contain fewer atoms per unit volume than the best vacuums attainable by human technology. So it doesn't really make sense to talk about them having sonic booms.",
"There are structures that look a bit like the ",
"shockwaves that form behind a sup... | [
"They are much denser than the volume around them, but that is still an extremely good vacuum."
] |
[
"With increasing medical treatments for birth defects and genetic illnesses, are we effectively nullifying Darwin's 'survival of the fittest'?"
] | [
false
] | null | [
"\"Survival of the fittest\" is a bit of a mis-characterization of natural selection. It's those who are best able to adapt and therefor reproduce who influence the direction of the species. ",
"That said, not it will not. We're continuing to evolve as humans. We may be evolving differently than we would without ... | [
"So what you're saying is, because we have the ability to fix any undesirable traits, we're effectively driving our own evolution?"
] | [
"To some extent, perhaps, though I don't think we have a deep enough knowledge to figure out how we'll evolve in response to our actions in each generation."
] |
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