title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Is the speed of the Earth's orbit around the Sun constant? What would happen if there was a change in the speed?"
] | [
false
] | Is the speed of the Earth's orbit around the Sun constant? If it is not, what would happen if the orbit speed sped up? If it varies by great deals, how does this affect us? | [
"Kepler pointed out that the planets orbit in ellipses not circles. This means the speed of the planet varies depending on which part of the orbit it is in. The closer to the sun the faster it will travel, the farther away the slower. So:",
"A line segment joining a planet and the Sun sweeps out equal areas durin... | [
"No, it's faster around January when the Earth is closer to the sun. That's why Northern summer is slightly longer than Northern winter. The difference between January and July is about 1 km/s, from 30 to 29 km/s."
] | [
"Seasons are ",
" caused by the eccentricity of Earth's orbit or the resulting velocity variations. ",
"The 23½° tilt of the Earth's rotational axis from the perpendicular to its orbital plane drives the seasonal weather changes in the planet's extratropical regions."
] |
[
"How fast would a fully-fueled Saturn V rocket be able to propel itself without any Apollo spacecraft payload?"
] | [
false
] | I was curious to find out what the final Earth-relative velocity of the third stage would be if it were tasked with lofting only itself into space (no CSM/Service or Lunar module on board). I'd imagine the total Delta-V would be quite ridiculous without 120,000 kg of mass on top. | [
"Well the S-IVB has a dry mass of about 10 tons, and fuelled mass of 119.9 tons. The CM/SM had a total mass of 30 tons and the LM had a mass of 14.5 tons for a total of about 45.5 tons of Apollo spacecraft payload.",
"The specific impulse of the S-IVB was 421 seconds.",
"Delta V = Isp * g0 * ln(m0/m1)",
"So..... | [
"Using the stage data from ",
"http://www.astronautix.com/lvs/saturnv.htm",
" :",
"That makes for",
"Edit: Screwed up the mass of stage 1. Now fixed."
] | [
"This is kind of tricky, as the specific impulse varies with altitude/atmospheric pressure and I'm not about to model the Saturn V's trajectory through the atmosphere.",
"But I will do the comparison, assuming the whole thing was flown in a vacuum.",
"The 1st stage, S-IC had a dry mass of 131,000 kg and a gross... |
[
"I know this question is difficult and inherently kinda flawed, but could we surmise how different the world & our body chemistry would be if water was a linear molecule (as opposed to bent)?"
] | [
false
] | null | [
"If water were linear, it'd strongly imply that you had two hydrogens that were double bonded to oxygen. While I'm sure a creative enough physical chemist could propose that this might be a wildly reactive transient species observable only under certain esoteric conditions, under our typical planetary SATP, it's n... | [
"It would have a profound impact because the boomerang shape of H2O molecules and the resulting dipole is responsible for the fact, that water is less dense in its solid state. This in turn is essential for life under water because the most dense water (thus the water in depth) has always 277,15K. ",
"Otherwise, ... | [
"If water were linear then it would not be polar and would not be a liquid at room temperature and pressure.",
"There would be no liquid water on earth."
] |
[
"Can baking soda be used as a deodorant/antiperspirant? Moreover, does baking soda present any health hazards?"
] | [
false
] | [deleted] | [
"Layman here with some chemistry knowledge.",
"As a deodorant well it depends, I am assuming you mean in the context of use on the human body and that would depend on what it is that is causing your body odor. Bicarb (NaHCO3) reacts with both basic and acidic substances, many odors are caused by basic or acid che... | [
"What's the best antiperspirant?"
] | [
"I don't know. Sorry, like I said I am a student of chemistry."
] |
[
"What gas can be separated out of water by sucking it in a Vacuum through a thin channel?"
] | [
false
] | Hey AskScience! Like any other child, I used to play with every kind of stuff while in the bath tub, and one of these things was an unused plastic syringe without a needle which I found somewhere in the house, I think I remember my friendly doctor gave it to me because found it interesting. Anyways, I played like a chi... | [
"Degassing liquids is necessary under many circumstances, for example UPLC/HPLC analysis, when bubbles in your solvents can interfere with the analysis, and in pump operation. ",
"http://en.wikipedia.org/wiki/Degasification",
"Also, if you've ever heard of decompression sickness, or the bends, a condition possi... | [
"Thanks for your answer, mate!\nYou and the nice wikipedia article you linked me explained it pretty well"
] | [
"You can also vaporize water this way if you pull hard enough. Lots of examples on youtube if you search for boiling water vacuum:",
"http://www.youtube.com/watch?v=jn1X_I8-9h8"
] |
[
"Investigating a Gene/Protein"
] | [
false
] | Hi there, my name is giselle and i am and microbiology undergrad student. Please forgive my english, i am from italy. I wanted to ask : How would you investigate in a gene/protein on the computer ? I know the experimental site, how to do that. But i want to get as much information i can get before starting with my expe... | [
"So this is the ",
"GenBank",
" acession for this gene/protein. Take those and put them into individual files. Then search on ",
"BLAST",
", which will give back the most likely hits. Download the individual results. You can also just search your gene name (",
"FADA1",
") which gives a list of all t... | [
"The prior comments are correct, ",
"NCBI",
" is a tremendous resource for raw data, and ",
"PubMed",
" has a very well indexed set of peer reviewed papers. ",
"This is a huge area of human knowledge, so don't be intimidated by how much information is available. It's easy to get overwhelmed.",
"I woul... | [
"Don't forget ",
"STRING",
", its an amazing dark horse even many biologists aren't aware of."
] |
[
"Why can't a bare LED have a wide spectrum?"
] | [
false
] | I ask this question because I was thinking about how white LEDs are made by secondary emission from a phosphor or multiple dies, and I thought why can't I have an LED that emits a smooth spectrum of light like a halogen bulb without a phosphor? | [
"The emission of light from an incandescent lamp is due to black body radiation which is continuous. LEDs use current/voltage to drive electrons across a P-N junction (from N type to P type semiconductor). The electrons which make it across the forward biased junction drop their energy level. When those electrons d... | [
"The band gaps exist in discrete levels and are very precise. Only certain elements are suitable for the bulk semiconductor and for the doping impurities which create the P and N types. Temperature can affect color somewhat. Here's a list of common colors.",
"https://en.wikipedia.org/wiki/Light-emitting_diode#Col... | [
"Nothing to add here."
] |
[
"How long would it take the sun to act its gravitational collapse?"
] | [
false
] | I´m not looking for the 5 Billion year answer. I mean it in the sense from which the Helium is done burning and the Sun begins to collapse into itself until it becomes a whatever it becomes... | [
"The sun is not massive enough to result in a supernova. It will expand as a red giant, blow off its outer layers, creating a planetary nebula, and end its life as a white dwarf."
] | [
"Oh right the limit was 1.4 Msun. Sorry"
] | [
"When the fusion is done the sun wil become a supernova and blow everything to pieces. The exact process of how this happens is not completely understood. "
] |
[
"Can sound travel in space if the noise is made in a gas cloud?"
] | [
false
] | I'm not really sure how to word it properly, but sound does not travel through space because there are no particles or at least very minimal atoms for sound to bounce off of and travel correct? So if a noise was made in a cluster of gas or nebula, would the sound travel? | [
"Sort of.",
"To act like a gas, a cloud of atoms has to be ",
". That is to say, the atoms must collide with each other, on average, more frequently than the period of the sound waves you're considering. The time between collisions can grow surprisingly long surprisingly quickly. In the low solar corona, for... | [
"If there was enough gas for the medium to be considered continuous, sound would travel fine. Go to a gas giant like Jupiter (pretty much just a giant mass of hydrogen/helium and other non solid material traveling through our solar system) and sound would travel just fine.",
"I think you were asking about someth... | [
"A nebua's density is so low, that it would be impossible for a 1 atm region to exist. It is less dense than any vacuum that we have ever been able to produce on earth. The average pressure inside a nebula is effectively 0."
] |
[
"Can an organ be donated multiple times? If so how many times?"
] | [
false
] | Say a 30 year old organ from person A gets put into person B. After 30 more years can the organ be donated to someone else? I'm also assuming it depends on the organ. | [
"Some organs can be reused. For example: a patient that gets a kidney transplant as a final attempt to save their life, and dies shortly after. If the death was not caused by the kidney it can be reused sometimes.",
"Death can injure organs though. The body dying can damage organs, and going through that process ... | [
"Don't quote me but I believe once an organis donated it can no longer be secondarily donated plus I don't think a person receiving an organ is eligible to become an organ donor...i may be wrong but pretty sure I'm not"
] | [
"I believe that this can be the case with the liver. A liver that is donated from a cadaver can be cut into 8 pieces or more where it grows into a full sized liver. So since a living person can donate part of their liver I'd assume that after donating a piece you will eventually regenerate the whole liver and be ab... |
[
"How does a snake's digestive system handle materials that range so widely in composition?"
] | [
false
] | That is, how does it manage to break down another animal's body in its entirety? reddit post from which my question stems: Edit: Thanks for the feedback! | [
"This news release",
" explains that snake digestion has been speculation for a long time, but researchers now have evidence that the snake's intestine/liver/other digestive organs are dormant and \"reduced\" between meals. Shortly after ingestion, they're activated and start producing mucosa, lengthening and in... | [
"It's also worth noting that not all snakes eat everything they put in their mouths. For example, egg-eating snakes don't eat the shell. They swallow the egg whole, then use muscle contractions in the throat to crush the shell against a protruding bone. After that, they swallow the egg's contents and regurgitate th... | [
"I think I may have the knowledge to answer your question but it is a little ambiguous. Many animals are able to eat all parts of an organism such as Hyenas which eat horns and bones. As you state it is mainly to do with enzymes in the digestive tract such as proteases, lipases and amylases. One thing that is spe... |
[
"[Aviation/Nautical] Ignoring that the engine would flood and whatnot, what would happen if a plane propeller were used to power a boat or submarine? How differently would it behave compared to a boat of the same model using a boat propeller?"
] | [
false
] | I assume it would go faster, because plane propellers have to spin faster to push the less dense air back at a high enough rate to get lift. Boats don't need enough speed to get lift, and the water is more dense, so wouldn't a boat propeller spin slower? I know the props are shaped differently, so that might be a facto... | [
"The aircraft propeller would need to either spin slower or be powered by a stronger engine, if we're not physically changing the prop. Drag is also increased, since that's dependent on fluid density/viscosity too. ",
"Since air is less dense than water, aircraft props need a bigger \"bite\" of air to generate th... | [
"The shape isn't the biggest difference. The radius of a prop planes propeller is many times larger than that of a boat. The force required to move a mass radially increases proportionally to the square of the radius. It's more efficient to move a radially smaller propeller faster."
] | [
"Oh, okay. That makes sense. I remember from 9th grade earth science that in order to stay with something, stuff on the outside of the curve has to travel faster than on the inside, like a river going around a bend, the water on the outside edge is traveling faster, and since the water on the inside is going slower... |
[
"When a nuclear bomb goes off underwater. Does it create a giant air bubble?"
] | [
false
] | If so how large is it? And how long does it last? | [
"It creates a massive steam bubble, it doesn't last too long (not sure on actual time it is there for) but something interesting happens when the \"bubble\" is there. The gas makes the bubble expand until it reaches the maximum size it can as the pressure forcing the bubble to expand becomes weaker the water pressu... | [
"Pretty much. Except Gypsy Danger probably would've been crushed/fried being close enough to the blast to be ",
" the bubble.",
"But it's a movie about giant robots fighting giant monsters. Rule of Cool is in full swing, and I'm okay with that."
] | [
"So... The underwater nuke detonation scene in Pacific Rim wasn't too far off?"
] |
[
"Can we create a single cell organism with basic chemicals/compounds? If it occurred naturally 4 billion years ago, can we recreate this event in a lab?"
] | [
false
] | [deleted] | [
"Not yet. There is a lot of work going on in this direction, and progress has certainly been made (such as simple cell membrane-like structures). But it has only been maybe 20 years since we even began having technology to begin looking at this problem, and it is an enormously complicated problem that early Earth... | [
"Theoretically, yes this could happen. Nobody has done it yet though, and it would be incredibly difficult to do. If this ever happens it would probably be the single biggest advancement in biochemistry ever: you are talking about literally creating life.",
"People have tried though! You should look into the Mill... | [
"Didn't the discovery of catalytic RNA eliminate the need for your second point? In other words, can't RNA essentially act as a nucleic acid/protein hybrid?"
] |
[
"Can someone explain what torque means in reference to vehicles?"
] | [
false
] | [deleted] | [
"If you say you understand the idea of force at a distance from an axis, then why is foot-pound / newton-meter not clear? They are both units of force times distance, they don't mean anything more than that. If you say that a motor has 1 foot-pound of stall torque, it means that if you took a 1 foot lever and put... | [
"Also on that graph is power, which is the diagonal line. This is not a separately measured thing, it's just the torque curve multiplied by RPM (times a unit conversion constant.)",
"Something I wanted to add. The actual equation is:",
"horsepower = torque x RPM / 5252\n",
"This is iterated along the torque c... | [
"Something that maybe wasn't all that clear, is that torque also tells how much you are able to tow. If you have some number of torque, you could accelerate a small mass very fast, butt a large mass would result in slower acceleration."
] |
[
"species age"
] | [
false
] | How do we know how long a species has lived on earth without a significant change in its morphology/physiology? ie. crocodiles and sharks | [
"Well, a species is a human definition for grouping things which have the potential to change constantly and gradually over long time spans.. And in the fossil record it has to be done on the shape and form of the preserved parts, rather than by genetics. We pick traits that we consider define a type of animal or p... | [
"To clarify your question, sharks and crocodiles aren't species, rather groups of species, or lineages. Many different species of sharks or crocs existed at different times: many went extinct, some gave rise to new species. So while sharks as a group have been around for hundreds of millions, the individual specie... | [
"We can determine evolutionary history even while ignoring morphology or physiology. One of the ways of doing this is by sequencing DNA or RNA, and looking at the synonymous changes present. Synonymous changes are silent, and as such they're less likely to be affected by natural selection and they're more likely ac... |
[
"Were all the elementary particles that exist in the universe today created at the Big Bang?"
] | [
false
] | null | [
"No. Particles can be created in other ways. Photons are created every time an excited atom or nucleus relaxes (among other ways). The fundamental quarks and leptons can be created through various particle decays and pair productions."
] | [
"No.",
"e− + e+ → γ + γ \n",
"an electron and a positron can produce two photons (and vice versa)"
] | [
"Certain type of articles decay within seconds, but some last for a long time. Turning on a flash light creates photons. "
] |
[
"Do engineers account for space debris when sending a spacecraft to Mars, for example ? Or are spacecrafts built with the ability to withstand minor collisions with space debris ?"
] | [
false
] | I must admit a lack of in-depth knowledge of how exactly things work in space, but to my knowledge there are different types of objects in space, of various sizes and traveling at various speeds through the (almost) void. Considering that, how would a man-built spacecraft interact with these objects and how do engineer... | [
"There's trash in earth orbit that is tracked. For our solar system space is pretty much empty. Voyager 1 did nothing to avoid hitting anything, there's just almost nothing there to hit it.",
"The chances of such a collision are very slim."
] | [
"Or are spacecrafts built with the ability to withstand minor collisions with space debris ?",
"You can do a few things to protect yourself from very very small objects. Tiny, really.",
"But at orbital speeds, ",
" can withstand an impact with more substantial objects. You just have to take your chances."
] | [
"NASA ",
"Protection of a space vehicle through the absorbtion of high-energy space particles "
] |
[
"What is the geological future of landfill sites?"
] | [
false
] | What will happen to all our buried rubbish? Will it be subjected to pressure as soil accretion builds up over it and be compressed into unknown materials? Will it even remain buried, or will erosion expose it and scatter its toxic contents to the wind and sea like some sort of ecological time bomb? Or will they eventua... | [
"I model the future of radioactive waste landfills, so I think about this a lot.",
"All your speculations could come to pass, in different ways. It is very much site dependent.",
"Since most landfills are really just a soft pile of unconsolidated materials, they will generally be subject to erosion, exposing th... | [
"Thank you for your answer - it's good to hear from a professional who knows about this stuff! I'll admit it's actually kept me awake at night. ",
"That seems like a pretty bleak outlook. And 30 years is a pitifully short sighted approach to managing them. Hopefully they will continue to be maintained properly un... | [
"To be fair, the design period for municipal landfills (and Hartford waste landfills) stipulates a 30-year design followed by a maintenance plan that includes examination every 5 years indefinitely. That is, as long as there is interest and funding. By comparison, low level radioactive waste near surface landfills ... |
[
"When sick, is it more sanitary to pull your shirt up to cough and sneeze into it, or into your bicep/elbow?"
] | [
false
] | Additionally, do the germs I send dispersing into my shirt permeate the fabric, or fall out and into the environment? Do the germs degrade quickly? | [
"According the the mythbusters that just gets it all over your hands, pockets and clothes. They did an episode on the best way to sneeze, and the best one they tested was sneezing into your elbow. The germs were restricted to only your elbow instead of being sprayed everywhere and on your hands."
] | [
"What about coughing when your really phlegmy? "
] | [
"use a hankercheif"
] |
[
"How much energy is in a wireless signal (radio, wifi, etc)?"
] | [
false
] | How much energy does a wireless signal (radio, wifi, etc) contain? Followup questions: For example: Does a wifi signal have more potential energy while someone is downloading vs when it is idle? Does a radio station signal have more energy vs tuning to all static? I assume information = energy, but how much? Thanks! | [
"First off let's switch to energy/time. If you asked how much energy a lightbulb used I'd have to immediately ask how long the bulb is on for its life... fuck that.",
"No. Each sine wave has a frequency and amplitude. You can arbitrarily increase the amplitude by dumping more power into the signal power is (V",
... | [
"Home routers with 802.11n wifi typically transmit from 10-25dbm, 1dbm is 1 milliwatt.",
"For non EE people:",
"10dBm is 10mW, 20dBm is 100mW, 30dBm is 1000mW.",
"A strong cell signal is around -80dBm or 10pW",
"GPS is around -110dBm or 9fW"
] | [
"Depends on the equipment. Home routers with 802.11n wifi typically transmit from 10-25dBm (10-315mw). Most cell phones transmit below 30dbm (1 watt)."
] |
[
"Why does the shadow of a jet plane cease to be a shadow at a certain altitude?"
] | [
false
] | I was on a flight yesterday and i was watching the point on the ground where the plane's shadow was as we ascended. At a certain altitude the shadow ceased to be a shadow and became a point of light brighter than the surrounding area. What is going on here? | [
"The disappearing of the shadow is fairly easy to explain just geometrically. ",
"This image",
" is made to illustrate eclipses but the same thing happens with any shadow. When you go far enough of the object casting the shadow, it will not block the entire light source any more at which point you get a partial... | [
"The bright spot sounds like an ",
"Arago spot",
", but those are generally only observed from circular openings/objects. Also, I'm skeptical as to how well Fresnel diffraction can be applied to situations this complicated (motion of air, clouds, height of the airplane, etc.)."
] | [
"Like this?",
"http://www.flickr.com/photos/minusmanhattan/6878666339/",
"If so, it's the diffraction of light around the airplane."
] |
[
"How does a computer processor wear out?"
] | [
false
] | Since everything ages and wears out somehow: How is it for a CPU? Can it get slower over the years? Make more mistakes? Or consume more power? What happens to it after running for a decade? | [
"Current flow causes heat. Heat causes expansion. Cooling allows contraction. Solid state components often fail when connections break down due to the constant cycling of expansion and contraction. ",
"I'm not sure about the cpu die itself but the connections where the die meets the conductors will be made fro... | [
"If they experience less heat differential then they will see less of this kind of stress at these points yes. All electrical and electronic devices have this issue, not just cpus. It can be minimised but not eliminated. ",
"I would think a server cpu would run at a reasonably constant temperature and experience... | [
"So server CPUs shjould be aging less, right?"
] |
[
"Would it be possible to create a cutter out of air by funneling huge amounts of wind through a tiny opening?"
] | [
false
] | null | [
"Air knifes are used in many industries, but it isn't for cutting. The use a blade of air for blowing lighter objects out of a stream of mixed density objects such as chopped up car parts at a recycling plant for example. Many other uses like drying objects off too. Air just doesn't have the density. Even with ... | [
"We have a water jet at my work for cutting ceramic bench tops. Just like you described, it uses garnet mixed with water at 66,000 PSI."
] | [
"I don't think air has the density to break anything useful. It simply wouldn't apply enough pressure as it hits the substance, especially as you're not compressing it by anything other than speed (this is technically the reverse, but the relative motion is the same): ",
"https://en.wikipedia.org/wiki/Ram_pressur... |
[
"Where do we get stomach flu viruses from?"
] | [
false
] | We've been in this pandemic for quite some time now. Me and my family have been very precautious by respecting all the measures that were suggested to avoid catching the virus. However, a couple of months ago I caught a bad stomach flu. I had a fever (38.5/39 °C at its peak) and a very violent diarrhea. I got tested fo... | [
"“Stomach flu” is often norovirus (and almost never actually flu, influenza). Norovirus is very different from SARS-CoV-2 (COVID-19) and influenza and many other viruses in that it’s extraordinarily stable in the environment. Whereas SARS-CoV-2 probably barely lasts a few hours in the environment, noroviruses can l... | [
"Viruses that spread through the fecal/oral route tend to be much more environmentally stable than those that spread through the respiratory route."
] | [
"It’s not a guarantee, but non-enveloped viruses do tend to be more stable than enveloped (",
"Survival of Enveloped and Non-Enveloped Viruses on Inanimate Surfaces",
")."
] |
[
"What happens to a compass if you hold it in space?"
] | [
false
] | [deleted] | [
"It aligns along whatever the local magnetic field looks like. "
] | [
"again, it would align with whatever the local magnetic field was. The local field produces a torque on the needle that pushes it around. But it's also a sum of all the magnetic fields at that point. So stellar fields, planetary fields, etc. would influence it. It's just that here on earth the earth's field overwhe... | [
"I would also point out that most compasses on earth only moves in 2 dimentions and we must orient the compass to be parallel with the surface of the earth to recieve a meaningful reading. In space where we do not always have a shared frame of reference with the dominant magnetic field, a compass that could move in... |
[
"What is the range of velocity magnitudes of the space rocks and stuff that fly by the earth (e.g. meteors prior to slowing down in our atmosphere, comets, etc)?"
] | [
false
] | I am trying to determine whether there is some continuity in the velocities and what that says about space rocks (for lack of a better, broader term) traveling in our neighborhood. it would seem curious to me if these speeds were more or less uniform, whatever that means on a cosmic scale. | [
"The velocities of a typical impact on Earth (for big stuff ie no atmosphere slowing) can be as little as 11km/sec to 70ish km/sec. So there is a huge range in velocities but the average is around 22km/sec. Does that answer your question?"
] | [
"not really because I am not interested in their velocities after they breach our atmosphere, additionally, I am interested in things that never hit earth."
] | [
"You misread my post those velocities are without considering what the atmosphere does with them. You will note the 11km/sec is the escape velocity of Earth. If you are not interested in stuff that hits Earth why did you mention the atmosphere? Essentially collisions in the asteroid belt are very low speeds (a few ... |
[
"Why does having diarrhea cause pain in the intestines?"
] | [
false
] | I understand why constipation is painful, but why is diarrhea painful? | [
"Diarrhea usually is caused by irritation to the intestinal lining. Your intestinal lining has pain receptors but your brain has difficulty localizing it specifically. The casing around the intestines (peritoneum) has pain receptors that your brain can localize. Irritation causes inflammation, which involves the re... | [
"An intestinal inflammatory process that affects the peritoneum results in sharp parietal pain. Dull visceral pain results from referred stimuli from sympathetic afferent signals. The pain that coincides with diarrhea is typically visceral and ",
" due to involvement of the peritoneum. ",
"You did mention the c... | [
"You are correct, and more accurate than I initially portrayed it. If I didn't make the peritoneum-sharp and visceral-dull distinction clear, your comment clears it up wonderfully."
] |
[
"Not every galaxy has a black hole at its centre, but what else has a high enough gravitational field to keep stars in orbit?"
] | [
false
] | null | [
"Galaxies do not rotate around their supermassive black hole, they just happen to lie at, or close to, the barycenter of the galaxy. ",
"What keeps a galaxy together is the collective mass of all the matter and dark matter within it, so even if there was no super massive black hole there the galaxy would still b... | [
"As far as I know, most galaxies are believed to have supermassive black holes located at their center. Regardless, for those that do not, this isn't going to cause any sort of difficulty for stable orbits of the surrounding galactic material. Stars, nebulae, and all the collective matter in a galaxy orbits around ... | [
"Just wanted to add a little bit of new insight into dark matter. There's a (relatively) new theory floating around (entropic gravity) that wouldn't require any dark matter to account for the rotation and extra gravitational attraction needed to keep the galaxy from flying apart. I'm not sure if you've heard of it,... |
[
"Is it possible for human flesh to catch on fire and burn like paper does? If so, how hot would that be?"
] | [
false
] | For some reason this question has been bothering me for the past couple days. I'm not a serial killer or anything, just curious. I understand that a body will burn. Like in a crematorium or when you burn someone at the stake but does their flesh burn like paper does? | [
"The human body can properly catch flame, given the right conditions - it's known as the ",
"Wick Effect",
". As the name implies, it's more like a candle than paper though, at least in this case."
] | [
"Wow, that is the exact answer to the question.. Thank you :) "
] | [
"I can't answer your question with any authority but when I burn myself glassblowing sometimes the skin turns to ash, this is at 1800 -2100 F. Depending on how long the glass has been out of the furnace "
] |
[
"How can a plant or tree grow massive without any discernible degradation of the soil around it?"
] | [
false
] | Since the matter making up the plant has to come from the soil that surrounds it, how come you don't notice large indentations or the like around large plants or trees from the missing matter? | [
"Most of the matter making up plants comes from the air."
] | [
"I'm not sure why this person was downvoted. His answer is correct."
] | [
"Feynman 'Fun to Imagine 2: Fire"
] |
[
"The cleaning lady in my office never rinses the soap suds off crockery and cutlery. Should I be concerned about swallowing detergents?"
] | [
false
] | null | [
"Very scientific. "
] | [
"propylene glycol. This is a common byproduct of petroleum, which as a group have been linked to cancer and lung damage",
"What? Propylene glycol is in anything slippery, and is in many food products. It's the base of pretty much every water-based sex lube. Oh, oh, now I read more closely. It's in a group, an... | [
"I'm also concerned about my colleagues. If the detergents are harmful, they're also at risk.",
"I'm surprised to hear that cleaning ladies doing dishes isn't more common. It's simple economics really... time is money. My boss would rather pay someone peanuts to wash the dishes than have his more expensive employ... |
[
"Why does hot water make clear ice cubes while cold water makes cloudy cubes?"
] | [
false
] | null | [
"The hot water has less disolved air than that of cold water. If you want really clear cubes, boil the water first. "
] | [
"To elaborate a little, when water or other liquids freeze, crystals of pure ice will form first, and any impurities or dissolved substances are forced into the remaining liquid phase. If you've ever tried to make popsicles at home (by freezing juice, soda, etc.), you may have seen this effect in action: you get a... | [
"I'm not sure what you're getting at - at the end of the experiment both ice cubes are the same temperature, yes? I don't see how that alone would influence the \"cloudiness\" of the ice cubes.",
"Anyway, I think the answer probably lies in ",
"solubility",
". The common gasses in air are all ",
"less sol... |
[
"Do conventional internal combustion engine work in zero gravity? Do we need a \"down\" for the oil in the crank case or could it just free float?"
] | [
false
] | So many unanswered questions. | [
"You don't need a down, per se, but most oil pumps scavenge from the lowest point. Even a dry sump system uses gravity to pull the after-use oil back to the tank and through the filter/coolers (if equipped).The motor would need to be specially designed to deal with any leftover oil , routing it back to a collection... | [
"Aerobatic airplanes have special systems to work with inverted fuel and oil, but they still assume there is gravity. There have been bladder fed fuel systems which would work without gravity, but a bladder oil system doesn't seem as straight-forward.",
"Four stroke RC airplane engines work with a fuel/oil mix m... | [
"Brilliant. The oil needs to move through the system to be effective, and conventional combustion engines rely on gravity to maintain the reservoir.",
"Thanks"
] |
[
"Why does peripheral vision give a better image at night?"
] | [
false
] | null | [
"Great question! Your eyes have two main types of cells for picking up light signals: ",
" and ",
". Rods are super sensitive - they can detect a single photon - but they can't see colour. That's what the ",
" are for. ",
" aren't quite as good at low-level light, but they give you great colour vision and h... | [
"Rods are unable to detect color. They are more similar to an active/inactive state. Cones (and their specific subtypes) are more sensitive to specific wavelengths, giving rise to sensitivity to specific colors of the visible spectrum. \nEach individual cell's state (rods AND cones) is integrated at each level of p... | [
"Thanks for taking the time to respond, super interesting! "
] |
[
"Can plants get cancer?"
] | [
false
] | null | [
"No. Not really. Not as we understand cancer in animals.",
"(Note - I am simplifying a lot here)",
"Plant cells are totipotent. They can divide to create any other type of cell, not just cells of the same type. If you take a leaf cell and place it in an environment more appropriate for a root cell, it will alte... | [
"http://www.nature.com/nrc/journal/v10/n11/full/nrc2942.html",
"Yes and no. Plants can develop tumor-like growths, whether it be from DNA damage, dysregulated gene expression, or active remodelling by other organism. But plant tumors aren't acute diseases that directly threaten the lifespan of the organism the sa... | [
"It's not unreasonable to apply the 'Hallmarks' model in plants, but you'll only discover that there are no real cancers in the plant kingdom.",
"A gall is not a cancer. It has some superficially similar characteristics, but it's not the same thing. Typical galls have limited growth, and the cells do not grow wit... |
[
"Doesn't the idea of absolute zero (no particle motion) violate the Heisenberg uncertainty principle?"
] | [
false
] | If an atom is at absolute zero and has no kinetic energy (and is therefore not moving), doesn't that mean you can measure its exact location and also know its exact momentum? | [
"Particles at zero kelvin do not actually have zero kinetic energy, they just exist 100% in the lowest energy state possible, which has the minimum kinetic energy.",
"Imagine a particle in a quadratic potential (V = k * x",
" where V is potential energy, k is a constant, and x is position). A classical particle... | [
"Yes, that's why even at (arbitrarily close to) absolute zero there is still some residual motion. That's why helium can remain a liquid at arbitrarily low temperatures without freezing."
] | [
"Temperature is a statistical mechanics concept and it's not entirely compatible with quantum mechanics. In particular, it's not very meaningful to talk about the \"temperature\" of a single atom."
] |
[
"Do amputees produce less blood than the rest of us? Or do veins/arteries \"stretch\" to fit the extra volume?"
] | [
false
] | null | [
"They produce less blood. The body doesn’t have a set quota for blood cell production that it tries to meet - your bone marrow isn’t permanently set to produce 5 blood per day or whatever.",
"Instead your body reacts to the state of your circulation, as detected by stretch receptors and other signaling pathways t... | [
"In one word: angiogenesis. Part of wound healing is establishing new blood vessels to make sure there is ample oxygen for both the wound healing process and maintenance of the tissue once the wound is resolved.",
"This process is actually largely coordinated by the immune cells responding to the injury and is a ... | [
"On a related question how does your blood circulate back to your heart if you lost a limb? The blood vessels going to the limb are not connected to the vessels returning to the heart anymore."
] |
[
"If the world gets EMP'ed would electronics that were not powered at the time of the EMP still work?"
] | [
false
] | Say your car was not on, or your cell phone was not powered during the EMP, would you be able to use your car or turn your cell phone on? | [
"An EMP would induct a voltage into anything with a coil in it regardless of whether it is powered. Might I recommend a Faraday cage? "
] | [
"That depends on a lot of variables. But unpowered devices would be almost as susceptible as if they were powered. The EMP induces a current surge in conductors through a spike in the local magnetic field...all of the energy comes from that magnetic spike. So gizmos don't have to be powered up to get fried. "
] | [
"As far as the energy coming from the magnetic spike, this is quite true. During a particularly bad solar storm in the 19th century, telegraph operators were able to send messages without electricity. Ambient energy from the magnetic interference was powering the lines. ",
"Source: National Geographic, June 2012"... |
[
"What is the definition of energy?"
] | [
false
] | null | [
"\"Force times distance\" is not the definition of energy, Work, a change in energy, is the line integral of a force over some path.",
"But more generally, energy (or really the Hamiltonian) is a quantity which is conserved in physical systems with time-translation symmetry."
] | [
"I was talking generally about units, not literally F*D. Of course the formal definition would be the integral.",
"That doesn't really work as a definition though, that's just a necessary condition. I don't think it's sufficient to say that anything that is conserved under time translation symmetry is energy."
] | [
"That doesn't really work as a definition though, that's just a necessary condition. ",
"I don't know what you think that means.",
"I don't think it's sufficient to say that anything that is conserved under time translation symmetry is energy.",
"The quantity which is conserved if the system is time-tranlsati... |
[
"What does it mean that the phase velocity or the group velocity of matter waves can be greater than the speed of light?"
] | [
false
] | In my textbook today I read that in matter waves that the phase velocity and group velocity can exceed the speed of light but we wouldn't be able to attain any information if it did. So in order to transmit information the wave must be modulated in some way. What does this mean? Matter waves can travel faster than ligh... | [
"I can point you to some references that explain this. The basic idea is that the front velocity cannot exceed the speed of light, so information cannot be transmitted faster than the speed of light, but you can find situations in which due to the nature of the envelope of the wave, a phase or group velocity might... | [
"Think of a set of ",
"periodic ocean waves striking a beach at an angle",
". The incoming waves are only traveling at the normal wave velocity of a water wave. Analogy = c. But along the edge of the beach the ripples striking a fixed point \"appear to be\" moving at greater than ocean wave velocity, Anaolgy >... | [
"Actually, the group velocity can exceed the speed of light; see ",
"this",
" on Wikipedia for a quick description of how this can happen. "
] |
[
"What is the physics behind a piece of paper gliding above a flat surface?"
] | [
false
] | If you were to throw a piece of paper in a parallel direction as the flat surface it would glide for a while and then stop. Does it have something to do with the fact that the air has to travel at a higher speed above the piece of paper due to it's shape and therefore creating low pressure. Whereas below the paper it ... | [
"So you basically model the piece of paper as a wing? "
] | [
"Yup. It isn't a good wing, but it doesn't to be for it's weight"
] | [
"Lift ",
"http://en.wikipedia.org/wiki/Lift_(force)",
" and the Ground Effect ",
"http://en.wikipedia.org/wiki/Ground_effect_(aircraft)"
] |
[
"Why are torque curves so different between various methods of converting chemical energy to rotational energy?"
] | [
false
] | (to be more pedantic it's more like a shift and a transformation, but you get my point) 1. Electric motors have roughly an inverse torque curve compared to the HP curve, which roughly looks like a squareroot function upside down. 2. Turbine engines also have an inverse torque curve compared to the HP curve. It looks li... | [
"Different kinds of electric motors have different kinds of speed-torque curves. Induction motors, brushed PMDC/brushless PM motors, series wound motors, shunt wound motors, switched reluctance motors, etc. all have difference speed torque curves. ",
"My question for you is why would you think that different te... | [
"Those torque curves you are quoting give torque compared to shaft rotational speed. Each of those ways of producing rotational energy have different a efficiency depending on what the shaft RPM is, and the efficiency curve can be effected by many things. In the combustion engine examples a lot has to do with int... | [
"You should probably specify which diagrams you are referring to, because the curves differ wildly depending on what exactly is being measured, how much load is being applied...",
"That being said the difference is mainly in the mechanical aspect of the energy transformation. You probably refer to asynchronous el... |
[
"Is it possible for a star of ridiculously high mass and the proper composition to effectively collapse into a black hole so quickly that no supernova is observed outside the event horizon?"
] | [
false
] | I understand (at a very high level) the life processes of a star, balancing gravity's pressure with fusion's outward-pushing energy, until (in some cases) the star begins fusing Iron, which is not an exothermic reaction, and gravity forces the mass of the star together past the Chandrasekhar limit where electron degene... | [
"No. The collapse doesn't begin from the outside-in, and the event horizon doesn't either. Rather, it's a ",
", and the event horizon sweeps out (always OUT) as mass is gained. It's better to think of the event horizon as something that's always potentially there, but only \"counts\" when all of the mass involved... | [
"Awesome, that does help me think about it (and makes the term \"Schwarzschild radius\" more sensible).",
"Do you know what is responsible for the two processes I did mention that (according to one source, anyway -- wikipedia I think, I'll dig it up in an edit) do create a black hole without a supernova? One was ... | [
"Photodisintegration is a mechanism to explain hypothetical \"hypernovae\" of stars that are right on the edge of what's possible in terms of the maximum mass of the star. In that case however, you get a truly vast explosion... and a black hole. ",
"In the case of core collapse, it's just what I said with the cor... |
[
"Why is a cavity with a hole a good approximation of a black body?"
] | [
false
] | Don't the walls absorb some energy, and also lose the energy? So it doesn't really absorb all the energy that is irradiated on it, because only the energy that enters the hole in the black body is fully absorbed. And even after that energy enters, it can leave through the sides (walls) of the black body, and not only t... | [
"If the hole is small, then what comes out of the hole is the radiation within the cavity.",
"If the sides of the cavity are not an ideal black body, then they absorb some wavelengths and reflect others. The usual rule is that a surface emits wavelengths with the same factor as it absorbs them. So if the surface ... | [
"The usual rule is that a surface emits wavelengths with the same factor as it absorbs them.",
"This isn't just a rule of thumb. If you had an exception to it, you could use it and another material so that when they're at the same temperature, one emits more light and the other absorbs more, which means that thei... | [
"Yes it would be. It´s an approximation but close enough to be a common way to display the effect to general public. Many universities have this as an standard home physics experiment I like this 2 in particular:",
"http://www.fas.harvard.edu/~scidemos/QuantumRelativity/PurcellsBlackBodyBox/PurcellsBlackBodyBox.h... |
[
"If light is emitted from a single source, would there be areas of darkness at distances far away from the source due to the increasing space between emitted photons?"
] | [
false
] | Let's assume light is being emitted from a star and the light emitted can be depicted as rays radiating from all around the star. Would the increase between the distances of the ray tips result in areas if no light? | [
"There are several people here answering \"yes\", whereas the answer is substantially more subtle that either \"yes\" or \"no\".",
"Your picture of a discrete set of rays is really not the right picture. The electromagnetic field you would get in the situation you described would be completely evenly distributed,... | [
"The twinkling of stars verses that steadier light from planets is due to atmospheric turbulence. Small \"cells\" of air rising and falling distort the light from stars.",
"On a very bright star, such as Sirius, this is so pronounced that one can see colors as this happens."
] | [
"The twinkling of stars verses that steadier light from planets is due to atmospheric turbulence. Small \"cells\" of air rising and falling distort the light from stars.",
"On a very bright star, such as Sirius, this is so pronounced that one can see colors as this happens."
] |
[
"Why do some medications, when taken on an empty stomach, make us vomit and other don't?"
] | [
false
] | [deleted] | [
"I have the issue where if I take my multivitamin on an empty stomach it's a projectile vomiting party"
] | [
"On my prenatal vitamins it said not to take them in the morning. I thought it would be okay just once, boy was I wrong! That was the only time I threw up during my pregnancy. And it was also the only time I projectile vomitted."
] | [
"There are many reasons this can be. If you have a specific medication or medications in mind it'd help if you listed them. Food can help reduce contact of the medication with your stomach and increase the rate at which food is moved through the gut. ",
"Some medications can directly irritate your stomach lining ... |
[
"How exactly does the Higgs Field directly control the Higgs Mechanism? What is the purpose of the Higgs Field?"
] | [
false
] | null | [
"I don't know that I can address the ",
" of any field, but I can describe the Higgs mechanism and the role the Higgs field plays in this mechanism.",
"The Higgs field is one of the fundamental fields in the Standard Model. It turns out that the parameters of the Standard Model are such that if the Higgs field... | [
"So electrons acquire mass by passing through the Higgs field.. but where do the electrons come from? I'm still trying to get a handle on Higgs phenomenon and physics at large.",
"I was reading a magazine and it said that particles pass through the field and gain mass. Where do these particles come from?"
] | [
"We don't know. In the Standard Model, we simply assert that there are certain fields. There are some underlying mathematical structures that constraint the possible collection of fields in some ways, but as to why we have the fields we do -- we just don't know."
] |
[
"Are humans genetically inclined to live a monogamous lifestyle or is it built into us culturally?"
] | [
false
] | Can monogamy be explained through evolution in a way that would benefit our survival or is it just something that we picked up through religious or cultural means? Is there evidence that other animals do the same thing and if so how does this benefit them as a species as opposed to having multiple partners. | [
"Ancestral humans were most likely polygynous. This can be inferred through sexual dimorphism (the relative sizes of male and female bodies). In species with high degrees of polygyny (ie, one male with multiple females) such as in gorillas, males are much more physically formidable than females, since they are esse... | [
"In humans, we still see sexual dimorphism, ",
"Male vs. female sexual dimorphism has been steadily decreasing in our lineage. That seems to indicate a trend towards pair-bonding (if not pure monogamy)."
] | [
"Yes, definitely. "
] |
[
"For laparoscopy, why is gas used instead of liquid?"
] | [
false
] | Sister just had appendectomy and she's experiencing the typical pain associated with the CO2 inflation from the procedure. I was wondering why CO2 is used instead of, say, saline. It would seem saline would reabsorb quicker and with less discomfort. In thinking of why I could come up with a couple theories of my own-- ... | [
"Also surgeons aren't generally used to operating in a liquid cavity (with a couple of exceptions) for instance it would alter the optics inside the cavity, if they were bleeding from somewhere it would be hard to tell how much or where from etc. "
] | [
"Cautery would work as long as the medium was electrically inert, as there are plenty of surgeries done under irrigant distention conditions (like ",
"TURPs",
"). ",
"One big issue is that when the surgery is done, you want that pressure to go away relatively quickly. With a liquid medium, you'd have a lot of... | [
"my first thought is the fact that 212f is the highest you're hitting under water and that's not enough to be functional for cautery devices even if you had a isotonic non conductive fluid that wouldn't leach out electrolytes(well, you can get higher focally, but usign cautery even in a good bleed is far more diffi... |
[
"What color would a nebula be to the naked eye?"
] | [
false
] | I'm given to understand that photos like these have all been 'colored in' Would nebulae just be a white mass, or would they actually have color? | [
"The Heritage team explains this a bit here",
". Short answer, our eyes aren't attuned quite like the color variations given in those images, but they are (often) based on true colors, especially if the image originated from Hubble."
] | [
"Really? I've never seen any color to the Orion nebula through my 8 inch dobsonian."
] | [
"To see for yourself, if you ever have access to a telescope -- check out the Orion Nebula, in the constellation Orion. Though telescope ",
"aberration",
" may be present and affect the colors seen, colors are ",
" noticeable! "
] |
[
"If soap breaks the surface tension of water, could it be possible to fall into soapy water from an extreme height and still survive?"
] | [
false
] | null | [
"It's a myth that the danger of falling into water is due to surface tension. Surface tension is really only enough force to hold up small insects. ",
"What's really happening is that since water is almost incompressible, when you enter the water you very quickly have to push a lot of water out of the way, and th... | [
"Not only do the air bubbles reduce the density of water, they also make it compressible, and the viscosity is likewise dramatically reduced."
] | [
"What about adding considerable air bubbles to the water like they do on some olympic 10m jumps?"
] |
[
"If a woman has had an ovary removed, does that mean she only ovulates every other month? If not, does that mean she will run out of eggs twice as fast, and go through menopause much earlier?"
] | [
false
] | Im curious because my girlfriend had one of hers removed at 17 because it was being a bitch (had a cyst) | [
"No and no. Both ovaries can produce eggs in any given month, though one usually dominates in any given cycle. And menopause has absolutely nothing to do with running out of eggs, thought they are often greatly depleted to somewhere around 10,000 (from around 400,000 at the onset of sexual maturity) . It's a hormon... | [
"Under normal circumstances, each ovarian follicle has two fates: death (termed atresia) and ovulation. In fact, it's estimated that ~99% of all eggs undergo atresia as opposed to ovulation. "
] | [
"A woman that has one ovary removed (called an oophorectomy) will continue to release eggs every month. ",
"Recent research",
" also suggests that females are able to produce eggs into adulthood through use of progenitor stem cells called oogonial stem cells, so the single ovary may be entirely capable of produ... |
[
"What do you call a person who has no genetic link whatsoever to their parents?"
] | [
false
] | null | [
"This happens in surrogacy. The woman carrying the embryo is the surrogate."
] | [
"So what is the scientific or social term for this person?"
] | [
"Surrogate"
] |
[
"How is suffering measured?"
] | [
false
] | null | [
"It depends on how you define suffering (e.g., physical pain, psychological stress, discrete negative emotions, dimensional negative affect, etc.). In most every case though, self-report is usually considered the only valid measure of subjective experience (e.g., Quigley, Lindquist, & Barrett, 2014). You can make... | [
"All of those things. The idea that physiology, behavior, facial expressions, BOLD signals, etc., map onto discrete affective states (e.g., suffering, sadness, happiness) in a consistent way is not strongly supported (see Quigley, Lindquist, & Barrett, 2014; for a comprehensive review see Barrett & Russell, 2014). ... | [
"You can make inferences about suffering from behavior, the face, psychophysiology, and hormones, but these tend to be unreliable.",
"All of these things are unreliable, or did you mean hormones? Can you explain further?"
] |
[
"Do obese people get as cold, in low temp. conditions as a normal weight person would?"
] | [
false
] | [deleted] | [
"You don't even need fat/blubber, just size helps a lot. Large organisms have a lot more thermal inertia.",
"In fact, sauropods are hypothesized to have been gigantotherms, as opposed to exo or endotherms; they maintained a constant temperature just through large size. "
] | [
"Fat people lose heat less rapidly than thin people. ",
"Source"
] | [
"The obligatory: This is AskScience, please refrain from anecdotes or layman speculation."
] |
[
"Why is it so hard to get rid of rabbits in Australia?"
] | [
false
] | Why have measures to get rid of rabbits not worked so far? If they have no predators, why not introduce some predators like they introduced the rabbits? | [
"Because they breed like rabbits, they have no natural predators, and the predators we introduce decide that kangaroos are tastier instead."
] | [
"Predators won't wipe them out. They may thin their numbers but they'll usually reach an equilibrium with their prey.",
"Worse: Australia has a lot of small mammals and marsupials that would be threatened by a new predator."
] | [
"Rabbits do have plenty of natural predators in Australia. Dingoes, snakes, eagles are all animals that would happily eat them.",
"Problem is that Australia turned out to be an excellent place for rabbits to breed. Plenty of burrow space, vegetation and a warm climate means that they don't go through a period of ... |
[
"How does tidal locking work?"
] | [
false
] | I read this : , and I got confused after 'bulge dragging.' I think a picture would help, but can anyone explain this in more friendly language? | [
"So, the fact that the earth is rotating fast compared to the position of the moon causes tides in our oceans. Simplified, the presence of the moon is dragging a lot of water all around the planet every day. This costs energy, of course, and that energy is taken from the Earth's rotational speed. Simplified, the pr... | [
"The water itself doesn't move with the tidal bulge. It's not as if water is flowing across the oceans, rushing from low tide in California to high tide in Hawaii. The bulge moves as a wave travels through a taut rope, traveling through the water. It does create some drag, but not as if water is being dragged about... | [
"The force of gravity decreases with the square of the separation between two bodies.",
"Let's take two bodies, one of mass M, the other of mass m, separated by a distance R. Their total gravitational attraction is GMm/R",
" Now, let's give one of the bodies a radius of r, and break its mass into two chunks - t... |
[
"Since mass increases as speed increases from relativity, can we have mass due to the fact that the galaxy is moving through space?"
] | [
false
] | So we move with the earth around the sun, the sun around the galaxy and the galaxy moves too. So relative to space itself, we are moving extremely fast right? So according the relativity telling us that mass increases with speed is this why we have mass? What would happen if we where not moving relative to space at all... | [
"No. The Earth's speed around the sun (~30 km/s) and the sun's speed through the milky way (~220 km/s) are nothing compared to relativistic speeds (~3x10",
" m/s).",
"In addition, it isn't really correct to say that mass increases with velocity. Relativistic momentum increases. Usually when we say mass we mean ... | [
"When physicists say \"relative velocity\" they DON'T mean relative to \"space itself\"-- that's what they call \"absolute velocity,\" something that many don't believe exists at all.",
"Relativistic effects are from the point of view of the observer-- as something gets faster relative to an observer, it would se... | [
"You should keep your units consistent or people might get confused:",
"3x10",
" m/s -> 3x10",
" km/s"
] |
[
"Why are all planets in the solar system orbiting in the same direction, and almost in the same plan?"
] | [
false
] | Couldn't there be orbits perpendicular to the Earth's one for instance ? | [
"When the solar system was formed, all the planets were formed from a spinning disk of debris that orbited the Sun. All the planets that formed have this angular momentum and continue in the same direction along roughly the same plane. "
] | [
"Couldn't there be orbits perpendicular to the Earth's one for instance?",
"Yes, but they would have to be captured objects (see ",
"/u/Stuck1nARutt",
"'s post), and gravitational interaction with the other planets would tend to draw them back down to the plane of the ecliptic.",
"Of course, if this capture... | [
"The planets formed from a disc of dust that circled the sun billions of years ago. The fact that its disk shaped has to do with what objects do when they orbit around the sun. Because of this, the dust slowly clumped together into larger and larger rocks, which then became planets.",
"(They always move in the ... |
[
"Why are Jupiter's colors not mixed together?"
] | [
false
] | The colors are caused by different compounds and with different properties I can see how you might see stripes for example. But when you look at a close up image, there are swirls of different colors all over the planet. Why don't they mix together more uniformly? | [
"This is a tough one, because we're still not really sure of what causes the different colors in the Jovian belts, nor, to be honest, are we really sure what their structure represents. Are they mostly an upper-level phenonemon, or do they go down deep into the atmosphere in the same arrangement? No one's sure. We ... | [
"I cannot find it at the moment, but I could have sworn that we had data now from measurements of sound waves that implied that the structure of jupiter had layers of chemicals and we were observing color based off how deep the circulation was traveling to the top layer."
] | [
"For the same reason that we see distinct boundaries in the earths clouds. \nThe same forces that create sharp cold front lines, or spiraling hurricanes on earth - which represent areas with different concentrations of water vapor, temperature, and pressure, cause the same visual effect on Jupiter, only there are m... |
[
"How few of a species can be alive in order bring it back from the brink of extinction and maintain genetic diversity enough to survive long term?"
] | [
false
] | I saw an article saying that there's only 5 northern white rhinos left in captivity (and I think in the world, I'm not entirely sure). With only those 5, is there enough genetic diversity that 2 breeding pairs, and an odd man out (I think another male?), could actually repopulate their species and bring them back from ... | [
"The general agreement is that a population needs a minimum effective population size of 500 to maintain a long term population (this is about 4500 adults). Long term is the key here, as you can have large numbers descended from very few without any consequences for a long time, the Northern Elephant Seal is an exa... | [
"It depends on a number of factors. Effective population size is ",
" the same for every species.",
"How much genetic diversity is already present?",
"What is the generation time?",
"How many offspring can the species in question have per generation?",
"Is the species purely sexually reproducing?",
"Wha... | [
"I'm not disagreeing with you, I find you make some awesome points. ",
"Just wondering where you got the 500 animals from? I've not heard that before. Surely theres a factor in there of how genetically diverse the population is/would be of a species anyway? "
] |
[
"How do water towers deal with the pressure drop when water flows out?"
] | [
false
] | [deleted] | [
"There is a screened vent at the top of all towers so the pressure above the water level is consistently at atmospheric pressure."
] | [
"screened vent"
] | [
"How does it keep out rainwater and small bugs?"
] |
[
"Is it possible for a planet to spin upon multiple axis?"
] | [
false
] | For instance, could a planet tumble through space, instead of having one axis of spin, having multiple? | [
"Not a planet, but ",
"Hyperion (moon of Saturn)",
" has chaotic rotation period and variable axial tilt; its orientation is unpredictable."
] | [
"Well, there is such a thing as a ",
"rogue planet",
".",
"Here's",
" an interesting explanation of why planets rotate the way they do.",
"Basically...",
"the bottom line is that stars like the Sun spin from the original angular momentum that was there in the solar nebula from which it formed. Not only ... | [
"Not really. There is a subtle difference between chaotic and random. Something that is chaotic is sensitive to initial conditions, but can still exhibit patterns. Hyperion's rotation can be predicted up to about ",
"36 days",
" into the future, but no further because when we try to model its rotation, differen... |
[
"Why do we feel the cold more intensely in the fall?"
] | [
false
] | [deleted] | [
"Its simply ",
"acclimatization",
". You're literally, getting \"used\" to the cold."
] | [
"Article says \"While the capacity to acclimate to novel environments has been well documented in thousands of species, researchers still know very little about how and why organisms acclimate the way that they do.\"",
"I was hoping for a little more information about how this occurs. (Also it makes little menti... | [
"There are ",
"quite a few",
" articles on this. But, we really don't know how for most organisms (including humans)."
] |
[
"How deadly are human viruses such as common cold to other animals?"
] | [
false
] | there were many case where viruses that are not that deadly to animals jump to humans and become deadly. (bird flu, coronaviruses) Are there any documented cases where viruses is not as deadly to human become deadly to other animals? | [
"It certainly seems like viruses jump species barriers all the time, but that's only because the ones that do are newsworthy!",
"Viruses need to get inside of a cell in order to reproduce. This requires binding between the surface proteins on the virus and receptor proteins on the host cells. Protein-protein inte... | [
"This does happen. And between different species of non-human animals as well. ",
"Herpes simplex virus type 1 is pretty benign in humans. It causes cold sores. In some species of monkeys, however, it is absolutely fatal. ",
"Cowpox virus is carried by small rodents and is fairly benign there as well. But it is... | [
"Herpes simplex virus type 1 is pretty benign in humans. It causes cold sores. In some species of monkeys, however, it is absolutely fatal.",
"This goes both ways. Many species of monkeys have potentially very deadly strain of herpes. So they have to be handled with care."
] |
[
"If plants use sunlight to produce food, why haven't they evolved to use the whole spectrum of visible light and only reflect green?"
] | [
false
] | Since plants are green that means that the green wavelengths of light aren't absorbed right? So why hasn't there been a plant that absorbs all the wavelengths of light and is colored black? | [
"Plants only use about 1% of the sunlight available, so there really isn't any need to increase the efficiency of that part of photosynthesis. The green color only originates because the first plant cells are thought to have evolved beneath photosynthetic bacteria that use a purple pigment (",
"http://www.nbcnews... | [
"There are ",
"some",
". But the big thing to remember is that evolution is a tinkering process, not a designing process. It only works by small iterative changes over time, not grand redesigns. It would be better to use all the light, the plant would get a lot more energy. It would have to dissipate more he... | [
"Isn't there one photosystem that absorbs blue light and another that absorbs red light? The blue photosystem absorbs one photon while the red absorbs two to do the same chemistry (or it may be 2 and 4). If this is correct, then a green absorber would probably waste a lot of energy because it would still have to ... |
[
"In a standing body of water (or any fluid), is one side higher than the other because of the earth's rotation?"
] | [
false
] | I know if we start a body of water into motion the side opposite the direction of travel will raise and the side closest to the direction of travel will lower. I can't think of what would happen once the "start" of acceleration has finished and the rotation has stabilized. As a secondary question, does the same thing h... | [
"No. The lake's water is already moving at the same speed as the Earth, so it's not accelerating East or West as the world turns--just straight down, which gravity more than takes care of. ",
", the Earth's rotation brings the ",
" overhead once a day & lunar gravity does pull at the water, producing an enormou... | [
"Actually even if the water is perfectly stationary to the planet's rotation, and even if there were zero tidal forces from the moon, you could get uneven water levels over a large enough body of water based on the Earth's gravity not being homogenous.",
"http://en.wikipedia.org/wiki/File:Geoida.svg"
] | [
"If we just consider a small body of water affected only by Earth's gravity and the rotation of the planet, then the water is experiencing acceleration due to gravity only downwards. Sideways acceleration is zero because the water has already the same angular velocity as the planet. It's an interesting question tho... |
[
"Can stress and anxiety increase body temperature?"
] | [
false
] | null | [
"Yes they can. It is of course more complicated. Acute stress vs chronic stress, peripheral temperature vs core temperature, you have to be specific. But in general, an acute sense of anxiety increases core body temperature due to the PSH (psychological Stress-induced hyperthermia) via adrenaline as sympathetic act... | [
"the stress of getting ready to puke certainly does. That's why you often get massive cold sweats after throwing up - your body is trying to cool down FAST. Something about the higher temperature helps trigger the clenching and pulsing motions your stomach and esophagus need to make to get solids out."
] | [
"Absolutely. Stress hormones are released which then puts the body in fight or flight. This in turn affects the hypothalamus which is responsible for keeping the body in homeostasis including appetite, sex drive, body temperature. Therefore the body temperature usually goes up because more energy is being burned tr... |
[
"Assuming there IS silicon based life there in the universe, what would they use as \"water\" or as their organic solvent?"
] | [
false
] | null | [
"Hi! Chemist who works with silicon here. Si-based life would have a very hard time of it, for these reasons:",
"Silicon is less electronegative than hydrogen, whereas C is more electronegative (Si is 1.9 on the Pauling scale, C 2.5 and H 2.1). This means nucleophilic attack (a common step in many chemical reacti... | [
"If water is available, there's not much reason to believe they wouldn't use it - carbon and silicon have near enough identical chemistry with water.",
"Otherwise, your options are quite limited. If it's too hot for water, you're really too hot for most simple liquids - you also don't really expect silicon at hig... | [
"There are A LOT of \"what-ifs\" to this question, but I would say probably just water. The reason that silicon is proposed as a possible basis for life is that it should behave similarly to carbon based life as we understand it.",
"That said, some astronomers studying Titan have proposed it feasible that life co... |
[
"Where does battery in phones, laptops, etc go when it's \"dead\"?"
] | [
false
] | null | [
"What do you mean?"
] | [
"Well isn't \"dead\" battery just no longer ionized? So I mean like how does the battery become unionized, and where does it go?"
] | [
"Un-ionized* idk what the word would be"
] |
[
"Why do stereo speakers make more or less noise when different people touch the input cable?"
] | [
false
] | Background:I unplugged my laptop from my speaker cable and was touching the end to make a buzzing noise from the speakers, I then proceeded to poke my girlfriend with same end and the speakers produced a much quieter sound. Is this due to differences in our body weight/size or for some other reason? | [
"The \"speaker cable\" you're referring to is probably the input cable for the audio amplifier that drives your computer speakers, and the \"end\" is a ",
"3.5mm stereo phone connector",
".",
"The cable contains two hot conductors and one grounded conductor. If you touch the connector on two contact points, y... | [
"Actually ",
"skin conductance",
" (essentially the inverse of the human body's electrical resistance in this case) is a major factor, hence my reference to it. Skin's conductance is greatly dependent upon its moisture content, which in turn is dependent upon the individual's emotional state. This is the princi... | [
"I suppose if I had considerably more information about OP's experimental setup I could answer all your questions more completely. As it stands, however, I'll defer to your obviously greater interest and emotional investment, and eagerly await the results of your researches into the matter. Best of luck!"
] |
[
"Why sparks from fire have orange color and sparks from electricity have blue one?"
] | [
false
] | null | [
"The flames of a fire are orange due to the the substances in the flame. Inserting different materials into said flame would change the colour, a popular science experiment in education.",
" ",
"Sparks are blue because of plasma. Electrons bind to, and leave, the atoms in the air. Each time they bind, they give... | [
"Usually this is a function of temperature and black body radiation. High temperature materials give off higher energy light, which is towards the blue end of the spectrum. Low temperature materials give off lower energy, redder, light. See ",
"https://en.m.wikipedia.org/wiki/Color_temperature",
"\nSo presumabl... | [
"The other answer is correct. Electric sparks are not luminescent due to black-body radiation but because of excitation of electrons, like in a fluorescent lamp. Very different mechanism. To a human eye black-body radiation can’t look very blue anyway, no matter the energy, but slightly bluish white at most."
] |
[
"Why do amps make noise if you lay your phone on top of them..."
] | [
false
] | My guitar amp makes a good amount of noise (beeps and swirling sounds) if I lay it on top. Why is that? | [
"Your phone is emitting EM radiation when it tries to talk to the nearest tower.",
"Your amp is acting like an antenna and because it's an amplifier, it's amplifying the weak signals it's picking up from your phone."
] | [
"most audio equipments is able to pick up such interference. It's therefore a good idea to keep phones away from audio equipment while recording or simply turn them off (or go into airplane mode).",
"Since your guitar can indeed act like an antenna, you can also pick up all kinds of other interference. Most guita... | [
"Not all phones will generate such a noise. GSM phones use TDMA for voice calls, the time-slots for the TDMA signal are 4.615ms in duration. When a GSM cell-phone is communicating with the tower (which occurs routinely even when not receiving or making a call) it will emit RF in a particular very high frequency ban... |
[
"What is the evolutionary reasoning behind our temples? (anatomy)"
] | [
false
] | [deleted] | [
"There are dozens of holes in our skull (think eyes, nose, mouth, cheekbones, spine....) but the temples are not among them.",
"But our evolutionary ancestors, the early synapsids (as well as our relatives the dinosaurs and birds) actually ",
" have ",
"holes in their temples",
", the ",
"temporal fenestr... | [
"Dat manner. \nKudos"
] | [
"Dat manner. \nKudos"
] |
[
"Is it beneficial to breathe in through the nose and out through the mouth when running?"
] | [
false
] | My dad (not a scientist) says that this method doesn't supply one with enough oxygen and ends up hurting in the long run. | [
"The benifits Of breathing through your nose is it humidifys the air and filters anything that may irritate your airways. The cons are it is a narrow longer tube that causes more resistance making breathing large volumes difficult. Most runners breath through there mouth, if you wanted to hear more you could cross ... | [
"I'm an avid runner, and I always breathe through my mouth (this only backfired once when I inhaled a fly). All nose breathing does is force me to slow down because I don't get enough oxygen to maintain a faster pace. The only breathing technique I adhere to is following a cadence of an odd number of steps for th... | [
"If you get a side-ache, start breathing in on when the opposite foot strikes the ground. Your side-ache will go away.",
"This actually has nothing to do with ",
" you are breathing (i.e. when the opposite foot hits the ground) and probably has more to do with the fact that you are focusing on your breathing, w... |
[
"Can someone give me a basic explanation of entropy?"
] | [
false
] | null | [
"Personally I find this much easier to understand than the \"energy that can't be used for work\" type definitions I got in highschool and early university."
] | [
"Personally I find this much easier to understand than the \"energy that can't be used for work\" type definitions I got in highschool and early university."
] | [
"Another way to get confused is to get lost in different concepts of information that are not equivalent. ",
"There is information theoretic information (data) and semantic information (meaning). Semantic information is called semantic content. An instance of information theoretic information (data) is understo... |
[
"How possible is human immortality?"
] | [
false
] | null | [
"'Biology'"
] | [
"'Biology'"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"It is hypothetical or speculative in nature. We do not allow hypothetical questions because questions that cannot be confidently answered with any available data often invite non-scientific speculation.... |
[
"What is our current understanding regarding muscle hyperplasia?"
] | [
false
] | In my cursory research it seems that muscle hyperplasia in humans is a bit controversial. My question is, "where does current research stand on this issue?" Also, if muscle hyperplasia does take place what is the mechanism by which it occurs? Thanks | [
"I have a Ph.D. in Exercise Physiology, this is not my area of research and the data I am remembering is about 12 years old so take it for what it is worth. I am keeping to generalities as I do not remember the specifics. I'll kick around for my old notes later and see if I can get some citations. ",
"Generally ... | [
"Ok, thanks. That's what was turning up in my readings as well. ",
"Is it true that stem cells (or the equivalent thereof) are recruited to form new muscle cells as well or is it mostly that muscle fibers divide to form new fibers when they are put under stress?"
] | [
"Historical footnote: back in the day people were using animal models to demonstrate that 30-60% of the increase in muscle strength was due to hyperplasia in animal models and said \"so obviously this translates to humans too.\" The quote is a little bit of hyperbole on my part but not to far off. ",
"Initial hum... |
[
"What is it about alcohol withdrawal that makes it dangerous?"
] | [
false
] | null | [
"Alcohol acts as a depressant on the nervous system, including the brain. Mind you, that does not mean clinical depression, but an effect on individual neurons - they are less likely to fire, their threshold to do so is higher.",
"\nOver time, the body adapts to the constant presence of alcohol by compensating, i... | [
"Alcohol withdrawal can cause ",
" - characterized by tremors, hallucinations (both visual and tactile), acute confusion with agitation as well as autonomic nervous system overdrive causing tachycardia, vomiting, sweating, hyperthermia and severe hypertension; it has a reported 5-15% mortality rate.",
"For a mu... | [
"\"With early identification and appropriate management, mortality from DT is less than 5 percent. This figure has diminished from the 37 percent mortality rate reported in the early 20th century....\"",
"Without modern treatment mortality is still very high - not all delirium tremens is identified correctly or m... |
[
"Are there any animals in the world that doesn't need sleep?"
] | [
false
] | If yes, which ones? :) | [
"According to the wikipedia article on ",
"sleep in non-humans",
", several species of fish and blind cave animals are suspected to never sleep. "
] | [
"That's simply not true. Circadian rhythms have been observed widely in both eukaryotes and prokaryotes, but they are not universal even in eukaryotes. Plenty of parasites and underground/underwater organisms don't have anything of the sort. Could you please cite your source if you're going to make such a sweeping ... | [
"I don't think animals without a central nervous system can be said to sleep? If so, sponges, at least, should qualify. Maybe also jellyfish."
] |
[
"Is it possible for a human to be non-sentient?"
] | [
false
] | null | [
"Does persistent vegetative state count as an example of this? You can read about other disorders of consciousness here: ",
"https://en.m.wikipedia.org/wiki/Disorders_of_consciousness"
] | [
"I don't know what you mean by \"functioning correctly\". Sounds like you are asking if there is such a thing as zombies. Then no, not really. ",
"People can sometimes give responses to questions while they are asleep. That might be the closest."
] | [
"Yeah not possible as far as we know. You may be interested in ",
"philosophical zombies",
" for the philosophical take on this."
] |
[
"Why do I feel a tingling sensation in my groin when I am up high or near a ledge?"
] | [
false
] | null | [
"This is the fight or flight mechanism, most likely triggered by the onset of adrenaline. This article and some of it's children may give you some more documented information.",
"http://en.wikipedia.org/wiki/Fight-or-flight_response"
] | [
"Makes sense, I just couldn't find a ton of info on that. Thanks for answering."
] | [
"No worries. Figured you just needed an idea of what you are looking for :)",
"That response is a side effect of my medication, so I'm familiar with it :)"
] |
[
"How far away are we from understanding prime numbers?"
] | [
false
] | null | [
"What do you mean by understanding prime numbers?"
] | [
"Are you asking about current research in ",
" new prime numbers on a computer? Or are you asking about something deeper like the Riemann hypothesis?"
] | [
"Are you asking about current research in ",
" new prime numbers on a computer? Or are you asking about something deeper like the Riemann hypothesis?"
] |
[
"Where does the heat energy come from that keeps earth's core molten? Will it eventually run out? And... What happens then?"
] | [
false
] | So is the energy the result of some ongoing cyclical process? Or is it just the leftovers from the formation of earth? Is it constantly cooling? And what will change if it does? Thank you science. | [
"I have never seen any evidence suggesting that frictional heating plays a significant role in heat generation with the earth presently, are you discussing this in terms of heat generated in this manner during differentiation and core formation? You are correct that radioactive decay is an important process, roughl... | [
"The heat comes from the friction of heavy metals sinking farther down to the core and lighter metals rising to the surface.",
"Wait, what? No. The Earth is already differentiated, and essentially has been since the iron catastrophe happened 4 billion years ago.",
"Radioactive decay is certainly a factor, but a... | [
"Thank you sir!"
] |
[
"Would DNA taken as a kid say 11, be comparable to when that kid is 40?"
] | [
false
] | [deleted] | [
"Yes, it would, by and large.",
"While DNA does mutate over time, in most cells this will usually get repaired and thus any differences at the bulk level (i.e. measuring from many cells) will be negligible.",
"There are always cases where this is less true, like cancers in which DNA repair mechanisms have been ... | [
"Unfortunately your question isn't very easily answered, not least due to the fact that you're making two big assumptions: one, that older men actually do have trouble having children, and two, that this is related to what is going on in all of the cells of those men.",
"For the first assumption, I don't think we... | [
"if that is true, then why do older men have trouble having children, if the dna is almost the same? does not follow."
] |
[
"Wondering if anyone can help me with this problem I have with electrons/sub-atomic particles."
] | [
false
] | This may be already simply explained, and I am by no means a physics expert, but I do dabble in the topic of quantum theory out of pure interest and curiosity. My problem is that electrons have mass (which must be detectable), but don't display any indications on how gravity specifically influences their experience, in... | [
"Or, with familiar things, the electron attraction between a proton and electron is about 10",
" as strong as the gravitational."
] | [
"The reason why gravity doesn't matter is because:",
"The effective gravitational coupling between two electrons of mass \"m\" is at the order of ( m/M_planck )",
" . While the electromagnetic coupling is at the order of e",
" = (1/137)",
" . Electrons have a mass of roughly 0.5 MeV ~ 10",
" GeV, while M_... | [
".. and we've never measured any electronic properties to more than about 12 decimal places. So for all we know, gravity could be a billion billion times stronger than we think it is at the electronic scale, and we still wouldn't be able to tell the difference."
] |
[
"What effects both long term and short term does MDMA have on the brain?"
] | [
false
] | [deleted] | [
"The symptoms of recreational use (which I assume you're aware of) of MDMA are mediated primarily by the serotonin and dopamine systems in the brain. It is thought that the dopamine system activation is responsible for the \"high\" feeling, pleasure and mood elevation, whereas the serotonin system activation may be... | [
"Here is a summary (unfortunately old, from 2000) of work done on MDMA. ",
"http://www.erowid.org/chemicals/mdma/references/mdma_research_summaries.shtml",
"There seems to be a fair amount of evidence that people that do MDMA frequently have cognitive defects. However, it's somewhat unclear what the cause and... | [
"A review that focuses on the serotonin-mediated effects of MDMA:",
"http://www.cmaj.ca/content/165/7/917.full",
"A study of acute and long term effects of the drug on the dopaminergic system in mice:",
"http://www.ncbi.nlm.nih.gov/pubmed/15083264",
"I tried to use articles that used less jargon-ey language... |
[
"Particle spin?"
] | [
false
] | Is there an easy way to describe how or why we say subatomic particles have "spin"? and what is spin? | [
"Spin is just the component of a particle's angular momentum that can't be explained by rotation in physical space. As far as we know, there's no deeper reason ",
" particles have spin."
] | [
"That's just a way to describe spin within general relativity; it doesn't propose any cause for it."
] | [
"One of the early experiments that contributed to the concept of spin is the ",
"Stern Gerlach Experiment",
". It introduces the concept of spin by ",
" showing the result we would expect without including in.",
"The basic idea is that you briefly pass a bunch of electrons through a non-uniform magnetic fie... |
[
"What would it take for Jupiter to ignite and become a star?"
] | [
false
] | Thanks. | [
"Theoretically it would take about 74 more Jupiters to do it.",
"\"For stars with similar metallicity to the Sun, the theoretical minimum mass the star can have, and still undergo fusion at the core, is estimated to be about 75 times the mass of Jupiter.\" ",
"Wiki"
] | [
"It would require about 75x more mass than it currently has. ",
"Stars ignite when their hydrogen begins to undergo fusion. Hydrogen begins to undergo fusion when its gravitational attraction can overcome its electrostatic repulsion. So in order for it to fuse, there is a minimum mass in which the density gets hi... | [
"OH..wait, the ",
"event horizon",
" isn't the size of the matter in a black hole. It is how far from center of the black hole something can be before it ",
"Miserys",
" your a**. As in, if you get that close (or closer) to the center you wouldn't be able to leave. Now, prepare for ",
"mind blown.",
" T... |
[
"If an aircraft wing provides lift, what is used to counter act this during inverted flight?"
] | [
false
] | Since the shape of the wing won't be changed at high speed (I'm familiar with flaps, slats, and variable geometry wings), how does the pilot/aircraft counteract the now downward force of the lift during inverted flight? I'm envisioning a F-16 at high subsonic or faster. Not slow flight. | [
"Not really true. Flat plate wings exist and work, and lots or aerobatic aircraft have symmetrical wings. It’s really mostly about angle of attack."
] | [
"The camber or total curvature of the wing itself is a large contributer to the lift of a wing. This camber can be changed based on the deflection of the flaps on the back of the wing. High performance aircraft like the fighter jets generally have thinner, less cambered wings because they are intended to travel at ... | [
"I think it might be quite instructive to look at an actual formula. This is the lift coefficient C for a ",
"Joukowski",
" airfoil derived via potential flow theory. It ignores friction and the airfoil can't be used in reality, but it shows some important principles:",
"C = 8πρU²R/c(α+β)\n\nρ = fluid density... |
[
"Are there any everyday macroscopic phenomena that are caused by the quantum behaviour of microscopic particles?"
] | [
false
] | Or "can I see the effects of quantum stuff with my own eyes" | [
"Interestingly, ferromagnetism is a quantum mechanical effect that we observe everyday in common bar magnets and refrigerator magnets. ",
"It can be shown that classical mechanics fails to describe the behavior of these magnets (",
"This theorem",
" is proof). It turns out ferromagnetism is a result of statis... | [
"A Bose-Einstein condensate would be an example of a macroscopic phenomenon due to quantum behaviour. It's a state of matter (similar to solid, liquid, or gas) in which bosons are cooled to nearly absolute zero, so that most will be in the lowest energy level available. This state of matter can exhibit phenomena s... | [
"The photoelectric effect and slit experiment are both quantum behaviors you can see with your own eyes, both occur due to quantum phenomena. ",
"More interestingly, all modern electronics contain microchips with are designed with quantum mechanics in mind."
] |
[
"How can I estimate the size of clouds I see in the sky?"
] | [
false
] | When I look up at the clouds, I am amazed by how huge they are. The challenge I am having difficulty with is understanding just how big the clouds I see really are. Maybe they're just little tiny clouds a few hundred feet wide, and they're really close to the ground. Or maybe they're thunderstorms 100miles wide with c... | [
"I am not a meteorologist, but can offer some geometrical perspective.",
"If you know the altitude, you can get the rest. From the angular position above the horizon and the altitude, you can get the distance by right triangle trigonometry. Alternatively, from the distance and the angle above the horizon, you ca... | [
"Yes, once you have the altitude, everything else follows. The second observer was introduced only to get the altitude (or distance) by parallax. If you can get that data some other way, then you only need one observer.",
"Happy skywatching!"
] | [
"This is exactly the type of answer I was hoping for. Thanks!",
"I came up with how to determine cloud velocity using only one observer. Assuming you have determined Altitude, you can select a cloud directly above you, watch it, and determine the angle it has traveled through over ",
" seconds. Then, it should ... |
[
"This blue lake in Guyana was created by bauxite mining. Why is it blue, and is it unsafe to swim there?"
] | [
false
] | I took these photos last year while visiting Linden, Guyana. It's a bauxite mining town, and you can find blue water lakes -- like the one I photographed -- spread throughout the barren areas where strip mining has taken place. The blue lakes are especially odd because most bodies of water in Guyana are brown from se... | [
"\"Lago di Tenno\" in Italy here",
"Red mud",
"Lausitzer Seenland",
"re-naturing opencast lignite mines"
] | [
"Could be some Copper(II) ions in the water.",
"Copper is not particularly associated with bauxite. There are much more likely explanations. See the comments by crusoe, Gloinson, and myself.",
"Not safe. Do you see anything living in that lake?",
"That's an argument against drinking the water, but not neces... | [
"Why are these lakes blue? It can't just be the reflection of the sky",
"See ",
"Color of water",
", which points out that pure water is naturally blue, and that \"It is a common misconception that in large bodies, such as the oceans, the water's color is blue due to the reflections from the sky on its surfac... |
[
"I've heard it said that we have no idea how glue works on a molecular level. How much truth is there to that?"
] | [
false
] | I mean, if we are improving adhesive technology (which seems to be the case), we have to have level of understand, right? It can't all just be sheer trial and error. Can it? | [
"There's some truth to the statement, but the idea that we have absolutely no clue how glues work seriously overstates our lack of knowledge. We know of many ways that glues might work, and different adhesives work in different ways, with different forces varying as to their importance. This complicates things a bi... | [
"One important thing to keep in mind is that an electron is not a \"physical object\" in the sense that you probably think. In fact, nothing is.",
"At that level, an electron is really just a math equation governing a probability field. ",
"No physical electron exists, merely the field is centered around the pr... | [
"One important thing to keep in mind is that an electron is not a \"physical object\" in the sense that you probably think. In fact, nothing is.",
"At that level, an electron is really just a math equation governing a probability field. ",
"No physical electron exists, merely the field is centered around the pr... |
[
"How closely can modern jet airliners fly to each other (not legally, but physically) while maintaining some semblance of control?"
] | [
false
] | Obviously there's a legal limit on how close planes can get to each other, but if that wasn't there, how closely could two similarly-sized airliners fly before wingtip vortices or other forms of plane-created turbulence caused issues? What sort of difference would it make if they were two differently-sized models (ex. ... | [
"I guess you mean flying directly behind one another?",
"Laterally and vertically they can get pretty darn close. But to follow longitudinally causes problems. Wake turbulence disturbs the air which both upsets engine airflow and airflow over the wings reducing lift. ",
"Military jets for this reason stagger ve... | [
"The biggest things around here are about that big. I wouldn’t be flying on the same runways as anything bigger. ",
"“A380, caution prop wash from departing Cessna 182...”"
] | [
"If I am flying a small plane, I would be waiting about a minute after a large jet left before taking off as I don’t want to get mixed up in their turbulence.",
"You should be waiting longer than that, unless your definition of a \"large jet\" is actually something like an E190. Although you can mitigate your exp... |
[
"A question about vision..."
] | [
false
] | So light causes a hyperpolarisation of photoreceptor cells, right? Does that therefore mean that all visual activity (say, in LGN and primary visual cortex) is actually a DECREASE in activity compared to when it's dark? Or does it switch to depolarisation somewhere? | [
"The cells that the photoreceptors synapse onto, the ",
"bipolar cells",
" can either be depolarized or hyperpolarized by photoreceptor glutamate release.",
"Since the photoreceptors release glutamate in the dark, and not when struck by light, bipolar cells that are hyperpolarized by incoming glutamate depola... | [
"functional MRI is my guess."
] | [
"functional MRI is my guess."
] |
[
"How is mass-energy equivalence inferred from E=mc^2?"
] | [
false
] | This may sound like a dumb question but what is in E=mc that is not in, say K = 1/2 mv ? Is it c? Or is it merely the way it is derived? | [
"E=mc",
" deals with inherent energy in a mass, which is to say, the rest energy of that mass (please feel free to correct me on some of these terms, I am not sure they are 100% accurate). K=1/2 mv",
" is the kinetic energy of a non-relativistic mass which is moving at non-relativistic speeds. ",
"This site... | [
"what is in E=mc",
"E stands for energy. Just like kinetic energy or potential energy.",
"c is a constant; c = ",
"299,792,458 (m/s)",
"2 is 2",
"m is the rest mass (this will be important later)",
"So the equation reads, energy is proportional to the mass times 299,792,458",
" So, if you increase the... | [
"Einsteins field notes"
] |
[
"(Physics) How can I prove the relationship between force and extension of different combinations of springs?"
] | [
false
] | [deleted] | [
"It's hard to rigorously prove Hooke's law, since it's not rigorously true. Obviously any real spring must break at some point, and in practice it'll have a non-linear response to compression/extension long before that. ",
"It's largely an empirical rule; you can't 'prove' it without making assumptions that end u... | [
"Which relationship? Hooke's law?"
] | [
"Yeah :)"
] |
[
"Finding a break in a long wire without cutting said wire (electric dog fence)."
] | [
false
] | I have an electric dog fence. The way it works is we have a 300 foot loop of wire that goes around our yard. Each end of the wire is attached to a transmitter that sends a low level FM signal through the wire. The dogs wear a collar unit that includes a receiver and a shock unit. When the dogs get close enough to the w... | [
"I am an electrical Engineer. Electric fences us AM radio signals to work. Get yourself a hand held AM radio, hold it next to the wire as it comes out of the controller. Tune it till you hear a noise obviously from the wire. No noise? I bet the controller is dead. Once you get the noise, tape the radio to the end o... | [
"Disconnect one end of the loop from the transmitter. Now, the only part of the wire that will be radiating a signal will be the section between the transmitter (on the side that's still connected) and the break. Use the dog collar as a receiver to figure out where that is."
] | [
"make sure you turn the power low on the collar if you use this method. I remember doing this and receiving several uncomfortable shocks before realizing I'm a fucking moron"
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.