title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Terraforming a desert?"
] | [
false
] | This is something I have been curious about for awhile but have never been able to get a straight or collective answer. How hard would be to terraform a desert? I don't mean doing it in a rapid and expensive pace, but more in a over time natural way but with the aid of man. Usually when I contemplate this idea, it star... | [
"Usually when I contemplate this idea, it starts with building a channel from the ocean. Allowing the ocean water to run in to an area and form a lake or two and then let nature do it thing to help spread the moisture in to the area. ",
"The area would have to be below sea level.",
"The area would keep filling ... | [
"Last I checked, the Sahara was a bit above half a mile above sea-level. It's dry, arid, and if you can somehow come up with enough energy to pump that much salt water up into the sandy soil, it'll quickly percolate into the water table fouling it. The heat and local climate will cause some of the water to evapor... | [
"Allowing the ocean water to run in to an area and form a lake or two and then let nature do it thing to help spread the moisture in to the area. ",
"The primary issue with this is that sea water is salty, and flooding an area with sea water isn't going to change that. Percolation through the ground doesn't chang... |
[
"Do electrons accelerating under gravity radiate?"
] | [
false
] | I understand that electrons accelerating as a result of an EM field will radiate as demonstrated by cyclotrons and EM transmitters. Do electrons spew photons when accelerating under gravity? | [
"The simple answer is yes, but this answer needs a bit of qualification. If you were sitting in an ",
"inertial frame of reference",
" (a region where an accelerometer would show zero acceleration), then if a charge object would be accelerating with respect to you with an acceleration a, then it would radiate e... | [
"I was so happy when you said yes, because I would have been so pissed if my year long electrodynamics class lied to me about this too.",
"Note for incoming physics undergraduates: Everything you know is a lie, and everything you will learn ends up being slightly more complicated lies that eventually get closer a... | [
"As a physics professor, this is Day one of every course. We are learning mathematical models which have varying degrees of success in predicting real world behavior. The real world is real. Our models are approximations. Occasionally our models are so good we can't measure any difference between their predicti... |
[
"What would happen if you used a defibrillator on someone who was living? Would it kill them?"
] | [
false
] | Cause i know with when trying to revive the dead with the defibrillator, the electric shock causes the heart to shock the heart into working correctly again, so would it be reverse on someone who is living? | [
"Reddit's acting up again, so I can't see the other comments at this point, but I would say it's somewhat dangerous, but not a sure way to kill someone.",
"Defibrillation is needed when the electrical charge pattern of the heart is out of whack. The shock from a defibrillator whacks all the charge back to a defau... | [
"Add onto this. There's something called R on T phenomena. There's a brief period after your heart contracts(depolarizes) that each cell cannot be depolarized again. Now each cell did not fire at the same time so each cell repolarizes at slightly different times. R on T phenomena can occur if the heart gets a shock... | [
"Short version: When done properly, that is a medical treatment. If done improperly it can kill someone.",
"Long version:",
"\nWe shock the hearts of living people all the time. It uses an almost identical procedure, though the name is different. ",
"Defibrillation, by definition, is only used on a heart that... |
[
"How did the new island appear from the sea in Pakistan?"
] | [
false
] | null | [
"The most ever recorded was the 2011 earthquake in Japan (the Tohoku Earthquake). The change in seabed depth was >25 m in ",
". The reason the tsunami was so devastating is because suddenly that part of the ocean was 80 ft higher than it had been seconds earlier."
] | [
"Earthquakes occur when there is sudden motion on a locked fault to relieve built up stresses. Here, slip on the fault strained (displaced relative to the natural position) the nearby seabed, causing it to rise 5-10 m. The now-exposed rocky body was formerly a shallow rock body (less than 5-10 m below the surface).... | [
"How much could such land-strip rise in extreme situations?"
] |
[
"If a supersonic train approached you while intermittently sounding its horn, would you hear the horn sounds out of chronological order?"
] | [
false
] | I'm also wondering what a steady horn would sound like to someone in the same situation. Full disclosure: I came up with this question at 2:00AM when a ridiculously long train horn sounded. I think the overnight engineers do that on purpose because they are evil. | [
"Yes, for the horn blasts that the train produced before it passed you. You will also hear the horn blasts produced after the train passed you, more quietly and in chronological order.",
"As for the continuous horn, in the ideal world, the sound you hear would be composed of two distinct frequencies: one from the... | [
"Let me get this straight....",
"The train would pass you. Then you'd hear the sounds it made before it got to you, backwards (both out of order and the individual sounds backwards,) and also the sounds it made afterward, but just very quiet?",
"Whoa. Science."
] | [
"I made a video (to help visualize the sound propagation) with audio to roughly emulate what would occur. ",
"http://youtu.be/aCa-r_-TJDI",
"I'm a video guy, not a physicist, so this isn't physically accurate at all, but it should give you a good idea. The doppler effect is ",
" because of the high speed.",
... |
[
"Would someone critique my intuitive understanding of chemical bonds?"
] | [
false
] | I'm an interested lay person who's been reading up on organic chemistry. I've come to realize that the shape of a molecule plays a huge part in the bonds it can form. This goes way beyond my high school knowledge of ionic bonding and the like. I've started visualizing chemistry in terms of potential energy. Imagine ... | [
"Here's a calculation that i did recently on the addition of a hydrogen radical to the surface of an azulene ring.",
" It was done on a computational package called Gaussian 03'. see if you can spot the low energy wells where the Hydrogen would likely sit.",
"http://en.wikipedia.org/wiki/Azulene",
"2d energ... | [
"People have a habit of taking a simple metaphor and running too far with it. Assuming that the metaphor is all inclusive and that anything they cannot understand that does not fit within the metaphor is incorrect and can be dismissed or should be hostally attacked. ",
"You shouldn't fall into that trap. With tha... | [
"Thanks, this was very interesting. So it sounds like for a lot of these, there is no equation that can be written: you have to do iterative computation to figure it out? I haven't read the PDF you linked to, yet, but I'm planning to later tonight."
] |
[
"Is there a \"true\" time of the universe?"
] | [
false
] | If two clocks synchronized with each other accelerate to different rates, than are brought back into sychronization, one clock will depict more elapsed time than the other. Well ... if we do this experiment with an infinite amount of clocks, won't one of them have the most elapsed time? Wouldn't that clock be in sync ... | [
"Not my butternut squash!"
] | [
"But how can time exist if it's just a human construct?"
] | [
"I'm going to punch you in your gentleman vegetables."
] |
[
"What are the most endothermic reactions?"
] | [
false
] | We always hear about the most exothermic. What are some of the most endothermic?? | [
"No no. Spontaneity is a separate concept from enthalpy change. One measures spontaneity with ",
"Gibbs free energy",
" change, which is a function of enthalpy and entropy change, and temperature.",
"Have you ever boiled water before? The phase change of water into water vapour is an endothermic process, but ... | [
"I think he probably means, most endothermic reaction that will take place spontaneously at room temperature."
] | [
"I think he probably means, most endothermic reaction that will take place spontaneously at room temperature."
] |
[
"When physicists refer to \"nothing\", what does that really mean?"
] | [
false
] | Arguments have been made that Hawking's statements that the universe can create itself from nothing are self-contradictory, because it breaks causailty. My hunch is that those making such arguments are just not familiar with the more complex aspects of physics, but then again, neither am I. I've heard of particles "p... | [
"You're probably talking about Lawrence Krauss' lecture \"A Universe from Nothing.\"",
"What he means is that if you count the total energy density of the universe as positive, and the gravitational potential energy as negative, it cancels out to zero."
] | [
"I think it's fair to say that there's no such thing as 'nothing' in the universe as it exists. All of space is filled with fields -- the Higgs field, the electromagnetic field, the gravitational field, and so on. All particles can be thought of as perturbations in those fields, and they all have infinite extent.... | [
"I think this gets a bit into philosophy however, if two sine waves destructively interfere so you see no displacement is there still two sine waves?",
"Or which interpretation of 1 - 1 = 0 is more correct. That there is zero, or is both 1 and -1?"
] |
[
"How does the Trammel of Archimedes work?"
] | [
false
] | for those of you who don't know what it is. Basically, it traces an ellipse. Can anyone explain the mathematics behind how this works? | [
"An ellipse can be thought of as a curve in the plane. If you draw a coördinate axis and label one of the coördinates x and the other y, you can describe the ellipse by specifying the set of points (x,y) that make up the ellipse. One way to do that is to specify x and y in terms of some parameter (if you think of t... | [
"Can anyone explain the mathematics behind how this works?",
"The Wikipedia article ",
"Trammel of Archimedes",
" does this."
] | [
"Ah. Well in that case, let me clarify my question:",
"What does it mean for the equations in that article to be \"in the form of the standard parametric equations for an ellipse in canonical position?\""
] |
[
"What determines our perception of \" fullness\" the weight of what we've eaten or it's volume?"
] | [
false
] | null | [
"Partially right. You can easily trick people into gorging on large amounts of food, by masking or tricking a person in regards to how much they have consumed.",
"The most immediate mechanism is cognitive, \"I have eaten a lot of food\". The next is, as you describe, mechanical detectors, \"my stomach is full\". ... | [
"The volume. Stretch receptors in the stomach tell the hypothalamus via the vagus nerve that it is full and that you should stop eating. But there are many other factors influencing ",
"hunger",
" and appetite. That link is a good place to start if you would like to know about the other factors."
] | [
"I believe that the hormonal signaling of fullness through leptin and ghrelin is the factor that mostly contributes to your feeling of being full. Leptin and ghrelin can diffuse through the blood-brain barrier and bind neurons in the arcuate nucleus of the hypothalamus. The importance of these neurons is shown by s... |
[
"If we know the chemical composition of something, say honey or maple syrup, why can't we synthesize it?"
] | [
false
] | Artificially flavored high fructose corn syrup imitations aside, what stops us from creating these things in exact replications? EDIT: A lot of great answers, thank you science folk! Let me refine my question a little then, since people are focusing on the examples I gave. I'm sure there are other things that are in sh... | [
"Many biologically produced substances do not have simple chemical compositions made of 1 or 2 elements or compounds. They might contain dozens or even hundreds of different compounds and trace compounds. The three main components of honey, for example, are ",
"but honey also contains ",
"in lesser amounts. ... | [
"For honey, it is much cheaper to just let bees do it. There are many cases of natural products that are cheaper to isolate from nature than making them ourselves."
] | [
"With the recent decline in the population of bees, it almost seems to make sense to synthesize the honey, to allow bees to eat to eat their product, to wean the world's population off the dependency. ",
"You're correct - we could indeed attempt to synthesize honey to give to bees - but the thing is... I don't t... |
[
"We all know that absolute zero is the lowest temperature achievable in our universe but is there a maximum? I don't mean maximum by \"there is x finite energy and matter and if we converted it all into heat that is the maximum\" but is there a point where we cant excite atoms any more?"
] | [
false
] | Thank you all for your responses Short answer: Planck Temperature (We think) Long answer: When entropy has past the point of diminishing returns. Unless its made in a lab. | [
"It sounds like you're asking whether there's a maximum possible amount of energy atoms can have. Generally, there is not, as far as anyone knows.",
"But the thing is, temperature isn't actually related to the amount of energy atoms have. Or rather, it is in most cases, but that's kind of a coincidence. It's not ... | [
"This is not the only thing that can happen, in some systems actually there is formally a maximum temperature, usually called the Hagedorn temperature, which is related to exponentially increased multiplicity of states. The idea is that if you add more energy to a system, instead of adding energy to the particles t... | [
"Actually Planck temperature is not the maximum temperature. It is just the the temperature at which our current understanding of the universe breaks down.",
"It ",
" be the maximum temperature, in the same way the Planck length ",
" be the minimum length, but until we have a theory of quantum gravity, we can... |
[
"What percentage of the Space Shuttle's (and SRBs) fuel was expended to lift it the first foot (~30.5cm) of it's mission?"
] | [
false
] | Earlier today in a meeting a business consultant said, "96% of a rocket's fuel is used to simply get it off the launch pad". I'm pretty sure this can't be true for launching items into low orbit, but I didn't have numbers to back it up with. I found some data for how much fuel is present at liftoff: But I can't find a... | [
"From Wikipedia about the SSME (remember x3):",
"The engine produces a specific impulse (Isp) of 453 seconds in a vacuum, or 363 seconds at sea level (effective exhaust velocities of 4,440 m/s and 3,560 m/s respectively), consumes 1,340 L (350 US gal) of propellant per second, has a mass of approximately 3.5 tonn... | [
"Thinking more about it, I decided to Google \"space shuttle mass versus time graph\", came up with this link: ",
"http://www.nasa.gov/pdf/516059main_ALG_ST_SSA-Mass%2012-15-10.pdf",
"Page 5 has the vehicle mass at 10 second intervals but as this is just a teaching exercise for students I have no idea how accur... | [
"The consultant is full of crap. I suspect it's some weird corruption of the fact that around 96% of the Space Shuttle's launch weight is fuel and fuel tanks. The SRBs weigh 1,300,000 lbs each and the external tank weighs 1,700,000 lbs when full. That's 4,300,000 pounds and the total Shuttle system weighs 4,470,000... |
[
"How does an image sensor chip in a camera detect and convert light to electrical signals?"
] | [
false
] | null | [
"The lens produces a projection of what is in front of it, you can see this by standing in a dark room, 5 feet in front of a TV, with a magnifying glass , and projecting the image of the TV on a sheet of paper.\nYour question is how that projection is turned into electrical signals, the pixels in the sensor are lik... | [
"One note: even high-end mirrorless and reflex cameras use CMOS sensors nowadays. Case in point: Sony α7 and α9 series, as well as the Nikon D850, D500 and down. All CMOS. "
] | [
"The Nikon D3000 was the last Nikon DSLR to use a CCD sensor, and was released in 2009.",
" "
] |
[
"What causes our stomach to rumble when we are hungry?"
] | [
false
] | I understand that it means we are hungry but why does it rumble? My 10 second rumble made me question it | [
"As the muscles of your digestive system push food through the digestion process, the food gets broken down to be used by your body. In addition to the food and liquids that move through your digestive system, gas and air bubbles also get into the mixture.",
"It is these pockets of gas and air that make the sound... | [
"This is because of peristaltic waves. Peristaltic waves are normal contractions of the gastrointestinal tract which help in churning and mixing of foods and cause the food to move along the passage aiding in digestion. This can occur even when your stomach is empty.",
"The sounds have been named as borborygmi.",... | [
"Top comment basically covers it. Just wanted to add that peristalsis between meals is caused by something known as migrating motor complexes (MMC for short). For those who want to learn more, the ",
"Wikipedia article",
" is a good place to start."
] |
[
"How far away from the Sun can something still experience \"day\"?"
] | [
false
] | Day is different from night because the part of a body facing the sun is brighter than the part facing away. At what distance from our Sun would the difference become imperceptible? I know, for instance, that on Pluto the Sun is basically a point, but is still significantly bright. | [
"The brightest star, Sirius, can cast a shadow under ideal conditions that the human eye can just detect. So I guess you want to know how far we'd have to be from the Sun before it's dimmer than Sirius?",
"About 2 light years."
] | [
"More like 8 light minutes away."
] | [
"More like 8 light minutes away."
] |
[
"How much does the glass in a window frame contribute to the structural integrity of the window?"
] | [
false
] | [deleted] | [
"There could be some merit to the tenant's argument. Breaking a window in the process of opening or closing it could easily involve flexing it, and that's the area where the frame provides only minimal support. (Of course, there are many ways to break a window beside flexing.) ",
"The ability to flex the window... | [
"I think windows are designed with room for glass panes to expand and contract with temperature changes, so they wouldn't ever really bear structural stress from opposite sides of the frame.",
"That being said, windows can have difficult to detect weaknesses that make breaking very easy. Sometimes normal interact... | [
"The presence of the second pane shouldn't have any direct relationship with the strength of the first pane, but if the first pane was already broken, then there's a chance the second pane could have had a chip or crack.",
"If there were any existing damage to the second pane, it might not take much for a crack t... |
[
"Is there any science behind \"near-death experiences?\""
] | [
false
] | I've seen experts and lunatics alike claim many things, but I never know what to believe. I haven't had a near death experience, but my own opinion is that is has something to do with your brain losing oxygen causing hallucinations (auditory and visual), though I have no hard facts, just anecdotal accounts from a few p... | [
"You should check the ",
"wiki page",
" for some basic info about many topics, as they usually link to studies. That page shows multiple ideas for them. Some of these seem to be from Parapsychology, which I don't know anything about...but I would be skeptical based on a few of the words they used to describe ... | [
"As a psychology student, I have read several studies and other literature on the subject, most of which show that is it a product of expectation, hallucination, or simply dreaming. There is also no proof for some of the experiences near-death experiencers have, such as leaving one's body and flying around the roo... | [
"Hmmm about what I expected, just wanted another opinion. Thanks!"
] |
[
"Looking for a chart showing the distribution of vertebrate species #'s, thought askscience could help."
] | [
false
] | null | [
"What do you mean?"
] | [
"A cladogram?\nYou could capture a screen shot and edit out everything above vertebrates from this ",
"image",
". A cladogram with ~50,000 species of vertebrates would impractical, I doubt one exists. Here is a ",
"spindle diagram",
" from the ",
"vertebrate wiki",
"."
] | [
"Hey wow, thanks!"
] |
[
"Sometime in the far far distant future, due to collisions of galaxies, will eventually everything be sucked up into black holes?"
] | [
false
] | And if so what would that mean for everything? | [
"Probably not.",
"While it is true, that galaxies within a group or cluster may move towards each other, the distance between clusters and groups usually increases over time due to the metric expansion of space."
] | [
"Probably not. Even the supermassive black hole in the center of the Milky Way is insignificant in comparison to the mass of the whole galaxy. When galaxies \"collide,\" nothing really hits anything else. The galaxies just become tangled in each other's gravitational interactions and merge."
] | [
"According to a new mathematical representation of the way that a schwarzschild black hole works, any matter that goes into a black hole (aka passing the event horizon) ends up being expelled in some other region of the universe or into another region in the multiverse. It also works through Hawking's information p... |
[
"Is there \"weather\" in the oceans not directly influenced by atmospheric weather?"
] | [
false
] | null | [
"If I understand your question right by what you mean \"weather\"...yes! There are currents and circulations that occur irrespective of the atmospheric circulations. Ekman pumping is an example of a circulation directly related to atmospheric circulations (more information and a demonstration: ",
"http://paoc.mit... | [
"copypasta from my answer to a similar question in a ",
"previous post:",
"Yes there is a direct analogy to weather in the sense that there are variable currents on the time and spatial scale of mesoscale eddies. In the atmosphere the storms and weather we experience at mid-latitudes are primarily driven by me... | [
"That Perpetual ocean link was pretty cool. I wish they would have let you to rotate the globe yourself and control the speed/time step. I would have liked to see if the equatorial currents shift with the ITCZ overhead (my guess is they do)."
] |
[
"How can deep sea creatures withstand the immense pressure? What’s different in structure between them and humans for example, that allows them to stay unaffected?"
] | [
false
] | null | [
"Mechanically, human bodies are capable of withstanding the immense pressure at the bottom of the sea. Our bodies are mostly water, which is an incompressible liquid. Most of our pressure-sensitivity problems come from the gasses (oxygen, nitrogen) in our bodies. ",
"There are three big reasons we don't have skin... | [
"The key realization is that pressure can't harm uniform objects; it only pushes the molecules temporarily closer. Water, muscle, tendons, and bone have broadly similar bulk stiffnesses and can be considered uniform in this context. The challenge is to fill the lungs with air of similar bulk stiffness, which requir... | [
"Deep-sea fish actually have substantially softer bones than shallow-dwelling dish, not harder bones.",
"https://www.nature.com/articles/s41559-019-0864-8"
] |
[
"Why does the flesh of an apple turn brown if exposed to air and also why does it turn brown or \"bruise\" when you drop it?"
] | [
false
] | null | [
"A very basic explanation from the below website:",
"\"Apples and other produce (e.g., pears, bananas, peaches, potatoes) contain an enzyme (called polyphenol oxidase or tyrosinase) that reacts with oxygen and iron-containing phenols that are also found in the apple. The oxidation reaction basically forms a sort ... | [
"When you break the skin of the apple or drop the apple and form an depression under the skin, you permit oxygen to come in contact with the flesh of the apple. There's an enzyme in the flesh of an apple that causes a reaction between the oxygen in the air and iron in the apple flesh that essentially forms rust. ",... | [
"Kind of relevant:\nIf you squeeze lemon juice on an apple just after cutting/peeling it, it will retain its nice apple color and won't turn brown. "
] |
[
"In the String Theory, what exactly causes all of the different Strings to vibrate continuously?"
] | [
false
] | From what I understand, all of these Strings are vibrating constantly and each Vibration determines the Charge and the Mass of the greater Particle, but what causes the constant Vibration? | [
"Starting with a classical string, we can integrate its transverse motion along the contour to get some kinetic energy. If we quantize the excitation modes, one could perhaps naively state that the ground state would have no oscillation, and each higher mode is a different standing wave mode. I suppose OP's questio... | [
"Once a string is formed, it must be in some configuration/some state. Any such state can be written as the sum of various vibrational states, so once the string exists, associated vibrational modes exist,"
] | [
"I'm not sure this is quite OP's question (though only OP knows for sure!). I think OP's question is more along the lines of why aren't all atoms in their lowest energy states? ",
"Also, in string theory, the lowest energy modes of the string are, in fact, the ones that correspond to the familiar particles (tho... |
[
"Since dung beetles consume feces, what is left in their feces? Do they defecate at all?"
] | [
false
] | null | [
"A key thing to understand with this is that the grass and other plant matter in the feces they consume is really, REALLY hard to break down into fuel and nutrients. Even the large herbivores specifically evolved to do so aren't great at it. You can break open a piece of elephant dung and find recognizable pieces ... | [
"another question- evolution map shows forest predate bugs by hundreds of millions of years, and bugs predate land animals. so does the dung beetle only show up after large animals do? what did its predecessors eat that it would evolve to specifically seek out mammal dung?"
] | [
"Evolution works on niches. Before large animals, they're was no piles of dung laying around, therfore nothing was evolved to eat it. Only after dung \"entered the landscape \" was this niche created. Some beetles at that point evolved to fill the new niche"
] |
[
"Question on the expansion of space vs shrinking of matter"
] | [
false
] | Hi! Ive always wondered, From the observations we know that space is expanding, but how do we know its not the other way around with matter shrinking, or light slowing down? Is there even a distinction between the three or just a shift of perspective? EDIT: after googling some, which i probably should have done prior t... | [
"So that might be a plausible explanation for the redshift of emission lines if the Bohr radius scales with time in a specific way. But I don't think it can explain the redshift of light from other mechanisms, like thermal radiation and synchrotron radiation."
] | [
"I don't see how a shrinking matter theory would reproduce the observed cosmological redshift."
] | [
"If that were the case (and I have no idea if it's a valid interpretation), then we'd expect to see a higher redshift for things close to us, since distant galaxies would have been \"larger\" when they emitted the light that we're currently seeing. Instead, we see redshift that increases with distance, which is ex... |
[
"Is herpes transmissible to other parts of the body?"
] | [
false
] | For instance, is genital herpes transmissible to other parts of the body? Also, is there an increased chance of transmission to a child from a mother with herpes? | [
"The primary risk to the baby is encephalitis (entrance at the eyes) and it is substantial, with catastrophic consequences."
] | [
"Yes you can transmit it to other parts of your body. If you have a cold sore and touch your lip, then your genitals, you can give yourself genital herpes. It is also possible to develop it on other parts of your body, but this is much more rare because hsv prefers the tender skin around mucous membranes (genitals,... | [
"Just to add to this, in an adult with HSV-1 that enters through the eyes (or nose, mouth) the infection is limited to the trigeminal ganglion, which innervates the face. It is from here that the virus lies dormant and can emerge in reactivation events to cause cold sores, etc. In immunocompromised individuals or i... |
[
"In chaotic systems such as weather are they chaotic inherently or because we lack the means to properly model them?"
] | [
false
] | null | [
"It's an inherent property, which is that the system, even if perfectly modeled, is sensitive to initial conditions. In other words, we can't know the exact positions and velocity of every single particle, and this propagates to a large uncertainty in a macroscopic weather system that depends sensitively on knowing... | [
"Yep"
] | [
"Yep"
] |
[
"Sodium chloride tastes salty to us. What would other sodium compounds taste like?"
] | [
false
] | null | [
"As a corollary, if you ever taste other types of common salts, such as Epsom salts (MgSO4), KCl, etc, they are still very \"salty\" in their flavor, but the character of it is different. Go to the supermarket and pick up some low-sodium salt (usually a mix of NaCl and KCl) and try out--you'll notice a pretty diffe... | [
"Also salty if they can dissolve in water. Our tongues are sensitive to the sodium ions. Other positive ions can be registered, too, but they act differently. ",
"Wikipedia has an overview",
"."
] | [
"That is the glutamate part as far as I know.",
"https://www.nature.com/articles/1602526",
"https://en.wikipedia.org/wiki/Glutamate_flavoring"
] |
[
"Do most mammals have an approximately even ratio of males to females?"
] | [
false
] | null | [
"No, and it appears to vary tied to things like population density (Kruuk et al. 1999) and hormone levels at conception (James, 2008).",
"References:",
"Clutton-Brock, T. H., & Iason, G. R. (1986). Sex ratio variation in mammals. Quarterly Review of Biology, 339-374.",
"James, W. H. (2008). Evidence that mamm... | [
"Nearly all animals have an approximately even ratio of males to females. This gets back to ",
"Fisher's principle",
",",
"In short, if there are more males than females around, it pays to have female kids. If there are more females than males around, it pays to have males. Whichever sex is less common wil... | [
"Well, sometimes in species like deer sickly mothers will have more female offspring. This is because in deer, only one male gets to head up the herd and mate with the females, and to get to that point the male has to be really high quality. The female can't produce such a healthy son, so there's less point to pr... |
[
"What are the pros and cons of vertical versus horizontal axes in wind turbines?"
] | [
false
] | null | [
"I've actually published some work on this =) Some advantages:",
"Vertical axis wind turbines (VAWTs) are omnidirectional; they work equally well with wind from any direction, whereas HAWTs need to be yawed into the direction of the wind.",
"You can put the generator and gears for a VAWT near the ground, which... | [
"Given the potential benefits, why do you see so many more HAWTs than VAWTs? Is it just because the design is better understood?"
] | [
"I'm deep into the aerodynamic R&D side and not so much the application and economics side, but I think that's a big part of it.",
"VAWTs are relatively new and the adoption of any new technology when you're talking about economic scales of that magnitude is always going to take a long time. You need to prove tha... |
[
"According to Wikipedia there are systems that have zero entropy at absolute zero. Does this cause an exception to the uncertainty principle?"
] | [
false
] | Pop science reader here. Forgive my ignorance. I've been reading article, and it made me wonder if it would be possible to determine the position and velocity of a particle within a system that has zero entropy. And if so, does that invalidate the uncertainty principle? | [
"It's not possible to determine the position and velocity of a particle in any system with any entropy. A system with zero entropy is in a quantum-mechanical pure state. (if you apply the von Neumann definition of entropy) Which does not violate quantum mechanics."
] | [
"This is a great answer, but needs a little expanding: The weird thing about quantum mechanics is that there appear to be two separate types of statistics at play in the world. The first is conventional statistics and probability theory, such as you might use to predict the odds in a game of Blackjack. It works ... | [
"Because of the uncertainty principle, every physical system (even at absolute zero temperature) has a zero-point energy that is greater than the minimum of its potential well.",
"What makes you think that's relevant? Zero-point energy is part of the ",
" of the system, not the entropy.\n(either that, or I've b... |
[
"How can this train move 1 ton of freight 450 miles on just 1 gallon of fuel?"
] | [
false
] | How is this possible? | [
"Because once they get up to speed, (lack of) significant rolling resistance plus a LOT of momentum/inertia equals efficient fuel use.",
"(they never said from start to finish, they just said 450mi...so 450mi...in the middle of the trip.)"
] | [
"Yeah, I'd be interested to know how much full it took to get it to cruising speed. "
] | [
"8 grams of deisel fuel?"
] |
[
"Why do we boil water to turn generators' turbines rather than something with a lower boiling point, e.g. ethanol?"
] | [
false
] | Would that not produce the same pressure with less energy? | [
"This is called the Organic Rankine cycle. You can read about it here: ",
"http://en.wikipedia.org/wiki/Organic_Rankine_cycle",
"The issue is with efficiency, the percentage of heat energy that is transformed into work. The theoretical efficiency limit, Carnot efficiency, is a function of the ratio of the heat ... | [
"Those are both Rankine cycles regardless of whether the expansion occurs through a cylinder/piston or a turbine."
] | [
"Those are both Rankine cycles regardless of whether the expansion occurs through a cylinder/piston or a turbine."
] |
[
"If it was possible to acquire all of the strains of the common cold and infect oneself with them, could one theoretically gain immunity to all available strains?"
] | [
false
] | That is, you grab an injection (probably more than one?) and purposely get infected with the 200+ strains of viruses that cause the common cold, would your body be able to gain immunity to all of them or would you just get really, really sick and possibly die...maybe all of the above? This scenario assumes that before ... | [
"This strategy would probably work against those exact strains. However viruses and other pathogens mutate pretty quickly to avoid this phenomenon of immune system \"memory\". I don't know about the common cold viruses, specifically. However, one of the best known examples of this is the influenza virus (flu). New... | [
"One thing to point out is that flu viruses mutate by changing their RNA sequence (by not repairing mistakes that happen in replication) but they also mutate by passing around genetic information between different strains of the virus. That being said, if you were immune to all the current strains of flu, then you ... | [
"Well, as was said, your \"susceptibility\" to being infected by ",
" of cold (commonly rhinovirus) would stay the same, only your bodies reaction, \"the sickness\" would be attenuated. That's the basis of immunity really, save for vaccines that target infectivity, i.e. stopping the pathogen actually establishing... |
[
"What would a natural body that orbits a moon be called?"
] | [
false
] | …and do we know of any? | [
"These are called sub satellites or, and I kid you not, moonmoons. We don’t see any in our solar system and they probably don’t exist because the gravitational forces would probably render their orbits unstable."
] | [
"moon-moon and submoon are the two terms i have seen most often in the literature.",
"We don’t see any in our solar system and they probably don’t exist because the gravitational forces would probably render their orbits unstable.",
"Recent work on the 3 body problem suggests that orbital stability of tertiarie... | [
"Maybe we were just unlucky. Venus could have a moon (or even multiple moons) but doesn't have one."
] |
[
"How do low frequencies in the electromagnetic spectrum penetrate objects, but \"visible\" light can't?"
] | [
false
] | How is it that frequencies low in the electromagnetic spectrum penetrate walls and other objects, and as you go higher up, why doesn't "visible" light penetrate through walls, so you can see through them? | [
"Okay, electromagnetics/RF/optics engineer and physicist here. Just made my account for this post!",
"First off, visible light is completely capable of penetrating objects, such as window glass. Futhermore, objects that are transparent to visible light (like glass) aren't necessarily transparent to other freque... | [
"why doesn't \"visible\" light penetrate through walls, so you can see through them?",
"I'm going to answer this from the opposite angle to everyone else, and say that it's misleading to think that visible light has an arbitrary tendency to be blocked and deflected by objects. It doesn't. Rather, ",
". Why? Bec... | [
"Thank you so much for your effort for answering this post! I wasn't expecting a long and such complex physics involved with the question!\nYour reply will help and prepare me in the future when it comes to A levels, so it doesn't shock me so much when I find out how puzzling science can be. Once again, Thank You."... |
[
"Is this \"Suspended Water Trick\" even remotely possible?!"
] | [
false
] | null | [
"No, it's not possible."
] | [
"I figured as much, but was curious if there was a scientific possibility of ANYTHING like this being possible, or how this trick was achieved other than special effects."
] | [
"haha no, clearly designed to troll people into spilling water all over the place."
] |
[
"[Climate]Why are tornadoes so rare in Europe, but almost \"common\" in North America (US in particular)?"
] | [
false
] | Tornadoes are rare in Europe, so two tornadoes (Luxembourg and Amsterdam) on the same day is even rarer. In the US, while we don't have tornadoes everyday, we have them often enough, usually over 1000 a year. Why do we have so many. Even Canada has only ~6% of the number than the US recieves? (no data on Mexico) Ent... | [
"One reason is that he large open plains of the central US allow the cold arctic air to mix with the warm air from the Gulf of Mexico and create a lot of turbulence. I’m pretty sure they are more likely to form and grow where the ground is flat and can’t disrupt the formation like a mountain would.\nThey do form al... | [
"https://horizon-magazine.eu/sites/default/files/tors_since2000.png",
"Tornadoes are not rare in Europe. Europe is in fact one of the world's tornado hotspots. Powerful tornadoes are less common than in the United States, but still occur much more than \"rarely\"."
] | [
"They are common in the Sahara, but are called something else.",
"Tornadoes are formed in flat open areas with convection, and moisture to form severe thunderstorms. ",
"Europe is hilly so only small less damaging ones would form. ",
"If they occurred in a rural area you would never notice."
] |
[
"What would an emulsion look/behave like in a zero gravity environment?"
] | [
false
] | I thought about density and gravity randomly and wasn't quite sure on this one. Would the mixture just spread in all kind of directions or would it stick together? Separated or completely mixed up? Let's take water/oil as textbook example My curiosity is counting on you, asksci | [
"The result would probably be similar to what happens with air bubbles in water globules in a zero G environment. The oil would collect into a bubble in the center of the water globule. For other liquids, the liquid with the higher density would be the outer layer.",
"http://www.youtube.com/watch?v=cXsvy2tBJlU"
] | [
"Thank you that was an excellent video."
] | [
"If it is truly a stable emulsion, then it should hold. Something like Mayonaise. But oil mixed into water won't be a very stable emulsion, and will fall out of an emulsified state pretty quickly. Though it isn't a science lab, I do have quite a bit of experience working with all kinds of emulsions in a culinary en... |
[
"Are there any scientists actively working on theoretical space ships?"
] | [
false
] | i.e. What we think of as science fiction. FTL drives? Alderson drives? Warp drives? Hyperspace drives? I know its all theoretical and you can't go faster than the speed of light? But could we get close to it? Is anyone even trying to solve these problems, or have we as a planet given up on anything faster than rockets? | [
"Yes. ",
"http://www.grc.nasa.gov/WWW/bpp/",
"EDIT: \"All NASA support to sustain cognizance on these possibilities has been withdrawn as of October 1, 2008.\" Dang, now I am sad."
] | [
"I think this article has a good answer to your question--basically, the technology that you're thinking of (skipping through space faster than the speed of light) would require new knowledge of physics first. So you might say that current physicists are working on the problem. "
] | [
"I def wouldn't say we've given up. However, we're still not ready to \"start working on space ships\" yet, there is still a lot of theoretical knowledge we need to gain before we start working on the engineering problem of building the space ships.",
"This is the sort of work that is being done in universities a... |
[
"Moon Question! If I am viewing in Northern Hemisphere..."
] | [
false
] | So - If I am viewing the Moon in say Northern Minnesota. I see a waning crescent that to me - looks like a big "C" in the sky. Would a person in say - Southern Argentina (in a spot roughly the same distance south of the equator as I am north) - would they see a backwards C? They aren't "upside down" from me - but they ... | [
"Yes, you would see it \"upside-down\"."
] | [
"In the southern hemisphere, the moon is upside down when compared with the north, as are constellations."
] | [
"Thanks for the link!"
] |
[
"Can someone explain to me how quark theory was even conceived?"
] | [
false
] | [deleted] | [
"'Quark theory' or 'quark model' usually refers to the original hypothesis that hadronic subatomic particles (protons, neutrons, pions, and their heavier cousins, but not e.g. electrons) were composed of smaller, more fundamental particles called quarks. At the time it was introduced it was a sort of phenomenologic... | [
"because I would love to actually understand how this works or figured out but I don't even know basic physics",
"I had hoped to recommend a popular science book about the development of the Standard Model but then I realized I don't know a good one. The trend seems to be to focus on relativity or string theory i... | [
"I would like to encourage more history of science questions here. However, if you don't get an answer, you can try ",
"/r/askhistorians",
", ",
"/r/historyofscience",
" or ",
"/r/philosophyofscience"
] |
[
"If photons don't have any mass then why does light get sucked into a black hole?"
] | [
false
] | [deleted] | [
"Photons have no ",
", which means they have no mass when they are stationary.",
"However, photons also just plain old don't exist when they are stationary. Photons always travel at the speed of light. So, while they have no mass, they do have energy, and energy is equivalent to mass. ",
"Also, black holes mo... | [
"The idea is that the black hole distorts space-time (the typical analogy is to place a bowling ball distorting a rubber sheet it's placed on). It is this bending of space-time that effects the photon traveling in space, not the gravitational attraction between the black hole and the proton, because as you correc... | [
"First, as currently understood, gravity is the curvature of spacetime. Since photons travel through spacetime, they are affected by gravity. In particular, the paths of light rays appear (to a distant observer) to bend in the vicinity of a massive object. If the curvature is severe enough, the light rays will beco... |
[
"can someone please explain the orbit of electrons around the nucleus of an atom"
] | [
false
] | [deleted] | [
"Electrons in hydrogen only go at around 1/137 the speed of light. It changes depending on how big the nucleus is and which energy level the electrons are in.",
"You don't use Einstein's equation, you use Schroedinger's equation with a Coulombic potential.",
"It does agree with the quantum world. Predicting the... | [
"Electrons in hydrogen only go at around 1/137 the speed of light.",
"This needs clarification. Electrons don't have a fixed position and velocity in their orbits, they exist as probability clouds: volumes of space where they are more likely to be found. However, their energy, momentum, and angular momentum are f... | [
"The view that electrons \"orbit\" the nucleus was thrown out a looong time ago.",
"Electrons exist in orbitals of probabilities about the nucleus, where the shape of the probability distribution is dependent upon the energy of the electron."
] |
[
"The particle affecting the B-meson particle?"
] | [
false
] | [deleted] | [
"Maybe. The problem is that the B mesons are messy composite objects bound together by the strong force, which is incredibly difficult to compute. So it's possible that we just haven't fully understood how the strong interaction works inside the B meson; or, perhaps more likely, we haven't understood the exact natu... | [
"Thank you for the detailed answer. Maybe its because of my immaturity in the Maths and Physics field, but the whole concept of angular deterioration is confusing. "
] | [
"Thank you for asking this question. I'd never heard of this anomaly before and it gives me some hope for new physics!"
] |
[
"Are tractor beams possible?"
] | [
false
] | I'm currently watching Ben 10 and some aliens have a tractor beam. It looks like a lot of fun and I was just wondering if it ever could be possible. | [
"Yes. ",
"http://www.forbes.com/sites/alexknapp/2013/01/27/scientists-build-a-working-tractor-beam/"
] | [
"Note that this is pretty far from a Star Trek like tractor beam. It only works for microscopic particles and you'll run into some problems if you try to scale it up.",
"I don't know the details of the method exactly, but as far as I understand, the basic principle is something like this. You shoot photons at the... | [
"Secured to what? I have no idea what kind of a tractor beam you have in mind here and what kind of objects you are pulling. But say you have two space ships, roughly the same size. One is using tractor beam to pull the other. The tractor beam device itself is secured to the ship but what is the ship secured to? No... |
[
"NASA is sending a mini helicopter to Mars. How are they certain a propeller will generate lift in that atmosphere?"
] | [
false
] | null | [
"Great question! I worked on Europa clipper and have used the same facilities that they use to test the helicopter for Clipper. Essentially, we put the helicopter in a giant chamber and pull the air out until it reaches the thickness of Mars, about 100 times thinner than Earth. We have ran tests with a CO2 rich env... | [
"The helicopter is suspended in midair. On the top are a few cables ( to ensure stability) and on the bottom, it is anchored to the ground with a rope and weight. The helicopter will not fly upwards as the propellers spin. On the bottom anchor, we will give it slack so once the helicopter comes up to speed (very qu... | [
"The helicopter is suspended in midair. On the top are a few cables ( to ensure stability) and on the bottom, it is anchored to the ground with a rope and weight. The helicopter will not fly upwards as the propellers spin. On the bottom anchor, we will give it slack so once the helicopter comes up to speed (very qu... |
[
"Are there any good nanotechnology-related experiments that children can do with basic household items?"
] | [
false
] | I know this is a little specific, but I'm looking for a hands on way students around middle school aged could learn the basic ideas behind nanotechnology through experiments that could be easily done. Nothing that requires specific items that one would not generally have in a home. | [
"Self-assembly can be explored by putting similar lego squares in a tray of water and then shaking the tray slightly. The legos will form up with each other through cohesion and will eventually form into a poly-crystalline and then single crystal structure. You can then point out crystal defects (where the struct... | [
"Here's something. It's not very dramatic, but it is a nanoscale effect: ",
"Link-PDF",
"If - and this is a long shot - you have some titanium metal lying around, you could anodize it. ",
"video",
" You use electric current to form a very thin layer of crystal on the surface of the titanium; because it's so... | [
"That PDF is fantastic! Your other recommendations probably won't work for me, but thanks for the help anyway."
] |
[
"Are there 128bit processors? Aside from RAM allocation, do bits even matter?"
] | [
false
] | null | [
"I'm going to answer your questions backwards.",
"Aside from RAM, do bits even matter?",
"Yes, very much so. A processor consists of many parts, but the ones relevant to your question are the ",
"registers",
". Registers are used to store data for operations that need to be done quickly - fetch/store operat... | [
"/u/The_Sober_Grudge",
" if we assume ASIC ",
"[1]",
" GPCPU (General Purpose CPU) then yes, very much so! Here comes the candy! ",
"/u/anidnmeno",
" much to your surprise a CPU that had 256-bit registers was introduced around 2004 by the now acquired Transmeta Corp. ",
"[2]",
"; its name was Efficeon... | [
"Yes Absolutly, But when you talk about the bitness of a processor has very little practical value. The chances you need to use a 16 bit value 65536 or 32bit 4294967296 you absolutely will need larger values. after 64bit 18446744073709551616 not so much but that' integer values. There lots of good reasons to ne... |
[
"Why do I feel nauseous when I'm hungover? Isn't it too late to vomit anything harmful at that point?"
] | [
false
] | I'm curious as to why I typically feel nauseous when I'm hungover, when it seems that if I vomit, none of the alcohol that I ingested will come up. Why does my body went to expel the contents of my stomach if it's not the contents of my stomach which are doing me any harm? Is vomiting at this point actually going to he... | [
"Because ethanol (alcohol) is degraded into ",
"Acetaldehyde",
". Which is toxic to our body; ~20-40x more toxic than ethanol itself. When you consume large quantities of alcohol, you produce large quantities of Acetaldehyde, putting your body into a toxic state. Our bodies know of a pretty dang good way to rid... | [
"Nice answer, but I really detest the whining about providing information when asked for. If you think it's too easy to come by the info then simply don't provide it. Why add a guilt trip to your answer when you volunteered to help?",
"\"I'm glad this food is to your liking, Hobo, but it's just bread and meat whi... | [
"Or trying to impress upon the OP that, IMO, he/she would learn more efficiently and to their liking by finding easy-to-find information on their own. It is more like \"Here is a 5$ bill, Hobo, but there is a soup kitchen right around the corner that provides meals and work so you can make your own money.\" This re... |
[
"Do exponents on units in dimensional analysis need to be integer values?"
] | [
false
] | A compound unit like a Joule has units of kg * m * s Are there any sensible/useful units that make use of fractional exponents like something involving s ? What, if anything, would that look like or mean? | [
"There is a stress intensity factor which comes into play when analyzing the stress field in a material close to a crack, (and the fracture toughness, the related material property), which has the slightly awkward unit of MPa m",
", or kg m",
" s",
" ",
"For notches, where the notch tip of angled (i.e. not ... | [
"Wave functions in quantum mechanics have the property of having their square (or, rather, the square of their modulus) represent a probably density. The units of probability density are (m",
" so, correspondingly, the wave function has units of (m"
] | [
"There's a famous result from dimensional analysis where energy content in a turbulent fluid is proportional to length to the 5/3 power. There isn't an obvious physical meaning to m",
", it's just how the units cancel.",
"Your fundamental base units don't explicitly have to be the SI base units, so you could in... |
[
"If money was no object, how could I make a black hole?"
] | [
false
] | EDITED AGAIN- I suspect that I have no idea what I'm asking. I apologize for being a douche with the maths. :P Posted to too. Having an discussion/argument/bet with the guys here. Is it possible to make a large (~10kg) black hole with todays technology? We've done some (very) basic calculations but to be honest it's ov... | [
"I don't mean to nitpick, but is that a typo? Ten kilograms, and \"large?\" The ",
" naturally occurring black hole would be around ten-to-the-thirty-one kilograms.",
"A black hole with a mass of ten kilograms — if one could be created, which I find hard to imagine in the extreme — would have a diameter of thre... | [
"In principle, you can make a black hole out of anything you want. Just start piling mass together, and eventually its own gravitational attraction will provide the pressure to make it collapse.",
"Since you said money is no object, let's make a black hole out of ",
"US $1 coins",
"! They seem to be the dense... | [
"Some years ago a friend of a friend took a trip to … I don't remember, Greenland or some godforsaken place. We were at a party sometime after, and he told the story of how one morning he woke up to find it was \"minus forty degrees.\"",
"\"Centigrade or regular?\" I asked.",
"Everyone chuckled a bit awkwardly.... |
[
"Terms in electrolysis which confuses me."
] | [
false
] | * In a simple electrolysis setup, there is an anode and cathode. The anode which is positively charged is where electrons are flowing away from and the cathode, which is negatively charged is where electrons are flowing to. Hence, is the anode the positively charged electrode, negative electrode? | [
"The anode is ALWAYS the electrode where the oxidation reaction occurs. Similarly, the cathode is the electrode where reduction reaction occurs. Just remember ",
"The anode and cathode switch depending on whether the cell is galvanic or electrolytic."
] | [
"I work with electrochemistry and you have NO IDEA how annoying the terminology is. So literally every time I go through any conversation, I restate what I mean by each term. There are 2 conventions that use opposite meanings. ",
"Here are the facts:",
"1) Electrons have a negative charge",
"2) Crowding elect... | [
"The anode and cathode don't switch, AnOx, RedCat always applies, but the charges are the other way around depending on whether you have a galvanic or electrolytic cell."
] |
[
"If a person is locked in an airtight container, how many trees would be needed to supply enough oxygen to keep them from suffocating?"
] | [
false
] | Trees consume carbon dioxide and release oxygen. People require oxygen and respire carbon dioxide. What is the balance in terms of the number of people and trees in order to get a stable system. | [
"Just a note: when there's no light around (i.e. at night), trees breathe and consume oxygen just like us."
] | [
"The amount of oxygen produced by a tree varies widely depending on the type of the tree, the time of day, how much light the tree is receiving, and so on. Not to mention the size of the tree!",
"Also, most oxygen in the atmosphere was not produced by trees, but from algae and other tiny photosynthesizing organis... | [
"This TED talk suggests specific plants that could allow you to live in a sealed environment. They aren't trees though: ",
"http://www.ted.com/talks/kamal_meattle_on_how_to_grow_your_own_fresh_air.html"
] |
[
"How come starch does not dissolve in water?"
] | [
false
] | [deleted] | [
"Starch is combination of two types of polymers of glucose, branched and unbranched. Amylose is the unbranched component, and usually has 300 to 3000 glucose units, which wind themselves up into a helical shape held together by hydrogen bonds. This structure doesn't lend itself to being soluble in anything.",
"Am... | [
"But ",
" does that make it insoluble in water? Glucose is soluble in water, and there are tons of other polysaccharides which are too, so why not starch?"
] | [
"Thanks for the answer! But since its 70% amylopectin, shouldn't it be fairly soluble in water? Or am I missing something?"
] |
[
"Which conic section is the strongest?"
] | [
false
] | I've always heard that arches were the best sort of support for a structure, but exactly which one? Is a circular arch better than an elliptical one? How do the conic sections compare when used to hold up a weight? | [
"From a mathematical standpoint, there's no universal definition of strength. If you want to build a structure, you'll always have to take other things into consideration, particularly material properties and outside forces. ",
"For instance, a semicircular bridge built out of aluminum might be very stable unless... | [
"So what sort of analysis is used to test the strength of a structure using various arcs types? If I knew the distribution of weight and stresses on a structure, would I be able to use a single mathematical tool to derive the best curve/shape?"
] | [
"Yes and no. That kind of analysis falls within the realms of materials science and engineering, where there are (somewhat unfortunately) even more questions. ",
"Every material has its own properties, such as hardness, strength, stiffness, and several others. Believe it or not, each one of those things is unique... |
[
"What prevents implants like pacemakers from being rejected?"
] | [
false
] | Is there some sort of coating applied; or a certain type of material used for construction? | [
"Implants do have to be made out of certain materials in order to 1)not be dangerous to you and 2)hold up to repeated and often pretty strenuous use for long time frames. There are some materials which are reasonably commonly used because they fit both those properties such as titanium (and various alloys), stainl... | [
"This is the correct answer, skitheloaf's is not."
] | [
"You are right in what you are saying and I do not meant to detract from your answer, just make an amendment: by antibodies (from the second sentence on) I think you mean antigens. ",
"Antibodies are secreted by immune cells in response to antigens. Antigens are things that induce an immune response. Antigens nee... |
[
"What causes the buzz associated with sleep deprivation?"
] | [
false
] | To clarify, by "buzz" I mean a feeling of euphoria, relaxation, and dizziness; I should note that this combination is actually fun. I'm not sure if this applies to everybody, but I have personally experienced and was wondering how common it is and why it happens. | [
"It's in large part thought to be associated with increases in central serotonin release, which results both in the promotion of wakefulness and the antidepressant effects noted by smarmyknowitall. Reference: ",
"(PMID: 10884045)",
". ",
"There is also evidence that the antidepressant effects of sleep depriva... | [
"Huh, strange. No euphoria here, I just start shivering (teeth chattering and all) like a madman even when it's 80+ degrees (F) out."
] | [
"I personally can get really giddy when really tired. I know some of my friends do too."
] |
[
"Polyphasic Sleep, or Going Directly Into REM Stages of Sleep. Efficient or Dangerous?"
] | [
false
] | null | [
"I think the problem was more with the phasing of the post text, not the title - you particularly used the phrase that it was a \"personal question\", as well as mentioning a specific experience - you just need to ask questions in general terms, asking what research exists, and etc. - and remove yourself from the q... | [
"I think the problem was more with the phasing of the post text, not the title - you particularly used the phrase that it was a \"personal question\", as well as mentioning a specific experience - you just need to ask questions in general terms, asking what research exists, and etc. - and remove yourself from the q... | [
"I think the problem was more with the phasing of the post text, not the title - you particularly used the phrase that it was a \"personal question\", as well as mentioning a specific experience - you just need to ask questions in general terms, asking what research exists, and etc. - and remove yourself from the q... |
[
"How can lasers get hotter by going through a magnifying glass?"
] | [
false
] | Doesnt this violate conservation of etendue? Can anyone help me understand what's going on here. | [
"I looked a bit further into your explanation involving negative temperature.",
"Negative temperature doesn't violate COE, in a laser it requires that there is population inversing in the lasing material. That's well know. A statistical definition of temperature as related to entropy is used to describe these sys... | [
"What I think OP means is that it's not the same for sunlight or other simple emitters. You can't focus the light from those sources to reach a higher temperature with an object at the focal point than the temperature of the source (so taking a massive magnifying glass and/or mirrors and focussing sunlight on an ob... | [
"If I understand the core idea of your question correctly - why we can focus a laser to heat stuff to some extreme temperatures, but cannot do the same with many other light sources? ",
"To start with - conservation of etendue still applies to laser light passing through passive optical systems, just as with any ... |
[
"Why are cartridges for old video game consoles (NES) including a RAM chip instead of using the system RAM?"
] | [
false
] | [deleted] | [
"The extra ram would have had to have been a part of the system's design at launch, which would drastically increase the price of the console. ",
"Consider, if 2kB of ram cost $5 in 1985, but 8kB of ram cost $24, then that would be a DRASTIC increase of the price of the console to include that ram in 1985. ",
... | [
"According to ",
"http://www.jcmit.com/memoryprice.htm",
" in 1982 when the original NES would have been designed (It was released in Japan in 1983) 1 MB of RAM would have been around $2000-$4000 dollars. So, 8 KB would have been about $15-$30. But, it wouldn't have just been the RAM itself. Many other chan... | [
"RAM was really expensive back then. ROM was where the game was held on the cartridge. ",
"If your game needed more RAM, or processing power, it was cheaper to add it to the cart, rather than add more memory to the console. To add more memory to a console you would have to redesign the motherboard among other th... |
[
"Why do we see the flash after someone takes a picture with flash?"
] | [
false
] | null | [
"Can you elaborate, please? Your question is a little vague. Are you asking why the light seems to linger for moments after the photograph is taken?"
] | [
"Oh sorry! Yes, I mean the light you can see when you blink a couple times after the picture."
] | [
"The photo receptive cells in your eyes become desensitized due to the bright light. Basically the signals that the cells send to your brain ignore some of the incoming light data for some time until those photo receptive cells readjust to normal lighting.",
"I couldn't find any sources that talked specifically ... |
[
"Can a reaction be oxidation/reduction and acid/base at the same time?"
] | [
false
] | null | [
"There are several ways you can ",
" what acid-base chemistry is. One of these ways is called the Lewis theory of acids which establishes a relationship between oxidation-reduction and acid-base chemistry. Let me quote my Oxford Dictionary of Chemistry:",
"[...] a ",
" is a compound or atom that can accept a ... | [
"Everyone else has done a good job answering this. I will add my two cents as a yale phd chemistry working in a physical inorganic laboratory.",
"Many energy relevant reactions (water splitting, proton reduction, combustion, even catabolic processes) involve both proton and electron transfer.",
"Most gen chem t... | [
"Absolutely. By the ",
"Lewis definition",
", acids are electron pair acceptors. If a species receives electrons, it is reduced, so many acids are also oxidizing agents. "
] |
[
"Why do some wines get better with age, and some wines go bad?"
] | [
false
] | null | [
"I'm also not a wine expert but it is different from spirits. Spirits only age in the barrel because they are distilled until they are primarily alcohol and water, with flavors added from the barrel they are aged in and sometimes botanicals. Wine is much more complex since it keeps all of the various chemicals from... | [
"\"Still potable\" doesn't necessarily mean \"better than when bottled.\" Red wines can get better with age, but there's going to be diminishing returns when you talk about such long time spans. The tannins that are present during bottling get mellower with age due to chemical reactions that continue to occur withi... | [
"Ahh. I wonder if they have an optimal age after which they start to decline then."
] |
[
"Serious Question: How can the sizing of women's bras be improved to give a more accurate sizing. Is there a particular formula(s) that has been overlooked."
] | [
false
] | null | [
"The current method for bra sizing takes into account only two measurements: bust girth (cup) and underbust girth (band). This is problematic because these measurements only take into account breast size, not shape. Other necessary measurements such as volume, curvature, density, and spacing, should be considered ... | [
"I don't think stores (like VS)are trying to convince women they are sizes smaller or larger then they are. The question is just if there's a more accurate way of sizing. I've noticed going into different stores (3 for me personally), that I have gotten 3 different measurements, even though they all did the same ba... | [
"You should check out the subreddit you linked to (",
"/r/abrathatfits",
"), as they are quite convinced they have it on lockdown."
] |
[
"Why is air resistance proportionally squared to speed?"
] | [
false
] | Please explain in geometric terms. Such as( the faster you go, the closer the air molecules become quashed, adding to the resistive force. Also if you can, please explain mathematically as well. Thank you | [
"The rather hand-waving explanation is this: When you go faster, the molecules hit you harder, so there is one factor of v. But also, your path per second is longer so you go through more air, which gives another proportionality to v. Hence v"
] | [
"From Taylor's Classical Mechanics:",
"The function ",
" that gives the magnitude of the air resistance varies with ",
" in a complicated way, especially as the object's speed approaches the speed of sound. However, at lower speeds it is often a good approximation to write ",
" ",
", where ",
" and ",
... | [
"You have the internet, you have textbooks!",
"Khan Academy covers tons of topics in bite-size chunks.",
"If that doesn’t have what you need, MIT has their entire curriculum online!",
"Good luck, and remember to eat & sleep once in a while. ;)"
] |
[
"How did prehistoric humans trim their nails?"
] | [
false
] | I'm curious about anatomically modern humans that only had stone tools, how would they have dealt with finger and toe nails? | [
"Like other continuously-growing structures like rodent teeth or animal claws, they would have been worn down through normal use. After all, life was a lot more hands-on before we got all civilized.",
"Chimps have been anecdotally observed biting their nails, too, but I'd imagine that's a fairly minor contributio... | [
"Wouldn't they also (as I do) just pick their nails if they got too long that it would be a hassle to use them in normal use?"
] | [
"Sounds reasonable. Many children just naturally bite their nails."
] |
[
"Is there any evidence suggesting that life might have emerged independently in more than one location on Earth?"
] | [
false
] | null | [
"That's not to say it is impossible. Our unicellular ancestors may have destroyed other spontaneously created life-forms either by out-competing them for food or by directly attacking them.",
"We have a sample size of 1 so it's really hard to draw conclusions about how easy or hard life is to form."
] | [
"Not that I'm aware of. Every form of life found on Earth uses the same basic mechanism for storing information and making proteins: DNA -> RNA -> Protein. This is known as the \"central dogma\" of biology. There a few other conserved mechanisms, like using ATP for energy, that support the idea that everything livi... | [
"That's a good point, there are a lot of scenarios where life could have arisen and then gone extinct without leaving any evidence. It's entirely possible, maybe even likely, that life had several \"false starts\" before it caught on. Of course, we'll never know because it wasn't widespread enough to leave an obs... |
[
"Does the consumption of animal protein cause heart disease and cancer?"
] | [
false
] | [deleted] | [
"Cancer and heart disease are a broad term that encompass many different but related diseases all of which can be caused by a lot of different factors beside diet (genetic, exposure to certain chemicals in the environment etc.). Equating animal protein consumption as the cause of cancer or heart disease is is like ... | [
"Except it doesn't hold up to empirical observation. Fish causes an even higher amount of TMAO but isn't linked to atherosclerosis."
] | [
"From a molecular basis, an average animal protein is no different than an average plant protein. There might be some glycosylation differences which some studies indicated may potentially have some effects on inflammation but those studies are far from conclusive and can never be really well done by their nature."... |
[
"Insulation. How does it work?"
] | [
false
] | Since heat transfers at a molecular level, how does insulation, such as a thermos or cooler work? | [
"Heat transfers by three ways: 1) Convection - material moving around, like liquids 2) Radiation - everything emits electromagnetic radiation, blackbody radiation 3) Conduction - objects touching transfer energy to equalize temperature",
"A thermos works by limiting conduction. This is done by separating the ... | [
"Aditionally, a (good) thermos limits all three types of heat transfer. Radiation is shielded by silver-coating the inside which works exactly like a mirror. The vacuum then reduces convection and conduction."
] | [
"A good thermos will be a double-walled container with a vacuum between the walls. This serves exactly the situation you bring up--if the heat transfer happens on a molecular level, remove the molecules from the equation. The vastly reduced number of molecules take much longer to move the heat energy from the inner... |
[
"Challenge: Can ice be made by man without use of electricity in a warm climate?"
] | [
false
] | I can't find anything on the internet about anyone ever trying. I was just curious if maybe you could channel air pressure with simple machines, compressing it to cool. Maybe not even achieve freezing temperature but just a way to naturally cool off. Edit: Wow! So many great answers. Answers are still coming in so I wa... | [
"Of course. There's no reason you'd ",
" to uses electricity to drive the compressor. In dry climates, low night temperatures in combination with evaporative cooling can be enough to form ice. ",
"In human history it's mostly been easier to harvest ice and store it well. The ancient Persians were ",
"quite go... | [
"You can do an extreme version of a swamp chiller. The evaporation of water is highly endothermic. By having enough water evaporate quickly you can freeze what is left behind. A porous clay pot in a windy, dry climate can pull this off from evaporation at the outer surface, freezing water on the inner surface. No p... | [
"Well, the basic principle is evaporative cooling; dry air gives a rapid evaporation, which means water can get quite cold if it's kept reasonably insulated. The wiki article on ",
"windcatchers",
" has some more detailed descriptions of a similar type of cooling system from the region.",
"For the ",
" tech... |
[
"My understanding is that the Earth will be engulfed by the Sun in a few billion years--what is the fate of the other, farther out planets? Will they be destroyed by the Sun, or float off into space for all eternity, or something else?"
] | [
false
] | null | [
"Our star does not have enough mass to explode in a supernova. will expand into a red giant until it engulfs at least all of the inner rocky planets (I’m not sure either how much it’s supposed to expand). After that, the sun will collapse into a white dwarf."
] | [
"Whether the Earth is going to be swallowed by the sun is still up for debate. We're pretty sure Mercury and Venus will be consumed but Earth is far enough away that it could go either way. Mars and beyond will be fine."
] | [
"In looking at the survival of the Earth (and other planets) there are two effects to consider...",
" ",
"First the mass loss of the sun causes the planets to migrate outwards. In the Earths case the results in an expected outward migration of roughly 1 AU (the same as our current orbital radius). I do not know... |
[
"Hey, AskScience -- If I point my finger at the sky, about how many galaxies am I pointing at?"
] | [
false
] | Inspired by , I was just wondering about the number of galaxies even in the deepest darkest recesses of our universe. So if I were to try to explain to my kid how massive the universe is (not going out of my way to avoid an eight-year-old's existential crisis, I guess), and had him point his finger at the darkest point... | [
"Great question. ",
"For reference, lets look at the ",
"Hubble deep field",
". Its about ~2.5 arcminutes across. For reference the moon/sun are both about ~30 arcminutes across, and for the purpose of this argument, I'm going to say your finger when it points covers an angular area similar to the sun moon.... | [
"The ",
"Hubble Deep Field",
" contains on the order of 3000 galaxies, and according to Wikipedia represents an area of the sky equivalent to a 65 mm diameter tennis ball at 100 meters. Since the human arm is roughly 0.8 meters, and a finger is roughly 2 cm in diameter, the Deep Field represents an area of, rou... | [
"Good point. The best experimental evidence for the shape of the universe is that it is indistinguishable from being flat and isotropic, so the logical conclusion is that it is spatially infinite. ",
"That is the universe goes on forever, but since its only 13.7 billion years old we can only see galaxies within... |
[
"Two flat, polished surfaces with a thin film of liquid in between: can we make it even thinner?"
] | [
false
] | Sorry if this is more a technical than a scientific question, but hey, I need help, and this is where the clever people are :-D Let's say we have, between a slide and coverslip, a thin biological sample sitting in an aqueous liquid. The presence of the liquid means that the surfaces are about 50 microns apart. But we... | [
"If you take a standard microscope slide and standard coverslip, you can easily get them within 1 micron of each other. Use some 1 micron diameter ",
"microspheres",
" and put a precise amount of liquid on the glass (using a pippettor). Calculate the amount of liquid to use, say 1 cm by 1 cm by 1 micron= 100 ... | [
"Squeezing them together will move them closer. Can't provide any figures, though.",
"Why do you need to do this?"
] | [
"Does a confocal microscope have the depth resolution to see what you are looking for? I used one of those in my lab in college and it was incredible."
] |
[
"How did we domesticate cats?"
] | [
false
] | They're not pack-animals (apart from lions I guess) and most wild cats are ferocious killers (as far as I know). So how did we manage to breed the small docile housecats? | [
"They actually domesticated themselves. Their domestication was their own choice. They started staying around us because we were a source of food, and we liked having them around because they keep rats away and they are clean. A mutually beneficial relationship"
] | [
"Note that all this is a bit speculative, because clearly nobody was running around doing ecological and anthropological studies at the time. But this should give you the general idea.",
"So picture a village in the Near East, about 10,000 years ago. There's a few hundred people living all in one place, growin... | [
"Yep.",
"Here's",
" a fun Smithsonian article on the topic."
] |
[
"Would a giant slide save you if you jumped from a plane at 35,000 feet and how big would it need to be?"
] | [
false
] | This question has been inspired by a TIL about how to survive falling from an aircraft ( )... If you were to fall from a plane at 35,000 feet, and someone were to construct a giant slide for you to land on whereby you would hit the top of the slide which is almost vertical and it would then gradually reduce the angle a... | [
"Your eventual contact with the ground, which will only occur at about 140 mph, should really be fourth on your list of worries when being flung from a jetliner at 35,000 feet. The larger problems are:",
"However, assuming that with a stroke of luck the trajectory was just right, a well-oiled half-pipe could tran... | [
"I'd say that it might theoretically work (like the landing area of a giant ski jump), but that it would have severe problems in practice. And with \"practice\" I mean even a controlled proof-of-concept experiment.",
"For one, you'd have to fall into the leading end at ever so accurate a speed and angle. In ski j... | [
"So if I was a billionaire with a death wish, I could build a giant slide the height of the Sears Tower and then jump out of a plane in some kind of presurised suit, and if I was VERY lucky I 'might' actually survive?",
"I now have a reason to become a billionaire - thanks :)"
] |
[
"Why do the tear ducts activate when you yawn?"
] | [
false
] | [deleted] | [
"There's no \"emotional\" or \"vestigial evolutionary\" connection if that's what you're asking."
] | [
"When you yawn, certain muscles in the face are used. These muscles also happen to squeeze your tear ducts, causing tears."
] | [
"fake yawn physiology does not equal true yawn physiology would be my explanation"
] |
[
"Why does the Earth spin?"
] | [
false
] | Did the collisions of millions of asteroids cause it to start rotating? Was it initially not rotating? | [
"The Earth spins because it formed in the accretion disk of a cloud of hydrogen that collapsed down from mutual gravity and needed to conserve its angular momentum. It continues to spin because of inertia."
] | [
"To add to this it is important to note that this has to happen.",
"In any given volume of particles the particles will be moving randomly in different directions and at different speeds. However, if you add them all up some cancel and some add to each other, you will find there is a net movement in some given d... | [
"The total angular momentum of the solar system isn't zero, no. All the planets orbit in the same direction, which is also the direction that the Sun rotates. Lots and lots of angular momentum."
] |
[
"Why are things cute?"
] | [
false
] | [deleted] | [
"Typically things we find \"cute\" tend to share characteristics of babies. Large, rounded heads, big eyes, small ears etc... so there may be a biological factor going on there."
] | [
"You seem to be onto something.",
"http://www.nytimes.com/2006/01/03/science/03cute.html"
] | [
"There was a ",
"fantastic TED talk",
" given on just that angle."
] |
[
"How significantly do plastic dental appliances, things like retainers, Invisalign, or night guards, contribute to the build up of microplastics in the body?"
] | [
false
] | null | [
"Generally microplastics are formed by either the degradation of plastics disposed of into watercourses, or from the shedding of plastic fibres from fabrics, ropes etc.",
"Large, solid plastic objects are unlikely to produce microplastics. You might as well worry about the miles of plastic piping bringing your wa... | [
"Cost vs benefit: I’d keep the guard. Missing molars are expensive and uncomfortable to replace."
] | [
"Cost vs benefit: I’d keep the guard. Missing molars are expensive and uncomfortable to replace."
] |
[
"When you record sound on your phone at a concert, why does it pick up the sound of everyone around you over the speakers, but your ears pick up the soundsystem?"
] | [
false
] | null | [
"Humans have the ability to focus on a single source and mentally filter out background noises. Your phone does not. "
] | [
"And why can't we focus on a single source in the recording? Quality of the recording?"
] | [
"Because from your ears' point of view the noise coming out of the phone is a single source coming from a single point in space"
] |
[
"“James Webb will not actually orbit the Earth - instead it will sit at the Earth-Sun L2 Lagrange point, 1.5 million km away” - What does this mean?"
] | [
false
] | I’ve been reading about the James Webb Telescope and struggling to wrap my head around exactly what “sitting at the Lagrange point” means. Does this mean it will orbit the Sun, following almost the same path as the Earth, but stay in the same place from the perspective of the earth? | [
"The James Webb telescope will not orbit the earth, instead it will orbit the sun.",
"Imagine drawing a straight line from the sun to the earth and then extending this line by 1.5 million kilometers. This is the L2 Lagrange point. ",
"Just as the earth orbits the sun in ≈ 365 days, the James Webb telescope wil... | [
"Wikipedia has a good article on Lagrange Points with image references.",
"https://en.wikipedia.org/wiki/Lagrange_point",
"The short version is that orbital dynamics aren't as cut and dry as \"orbiting the Sun\" being distinct from \"orbiting the Earth\"; sitting at a Lagrange Point is about halfway between tho... | [
"What's even more interesting is that you don't really \"sit\" at a Lagrange point, you orbit it. So it's orbiting an empty point of space while orbiting the Sun along with that point. ",
"https://en.wikipedia.org/wiki/Halo_orbit"
] |
[
"Colors--Light vs. Matter"
] | [
false
] | This question originates from third grade art class, where I was indoctrinated into the red-blue-yellow primary color schema. In later physics classes, I learned the red-blue-green light scema and how reflection and wavelength determine an object's color. My question: why does mixing (for example) green and red light r... | [
"Matter creates color by absorbing all other colors than the one you see. When you mix paint, you are absorbing more and more colors. ",
"Light sources creates colors by emitting only the colors you see. Hence when you mix light, you're emitting more and more colors.",
"tl;dr Paint subtracts colors, light adds.... | [
"The ",
"Wikipedia article",
" on the topic is a good explanation of the topic. The gist is that there is a difference between additive and subtractive color mixing. In the extreme case, this means that adding all colors produces white light, while subtracting all produces black light. The later case is perhaps... | [
"To elaborate, the crux of it is that physical media like paint ",
" light, and the color that we see from it is what it does NOT absorb. So if you take two colors of paint and add them together, they will absorb all of the colors that ",
" of them absorbs, reflecting only those that ",
" absorbs.",
"Conver... |
[
"What are the odds a younger sibling would be a clone?"
] | [
false
] | null | [
"Functionally nil. There is such a large combination of genotypes in gametes as to be essentially limitless. This is due to crossing over and independent assortment of chromosomes during meiosis I. Then, consider the fact that you have two different gametes uniting on an essentially random basis during fertilizati... | [
"Your logic is killing my chances to market mini-me's...",
"Thanks for the information."
] | [
"You don't just need to worry about the crossover, but whether or not a sperm with the right set meets with an egg with the right set. "
] |
[
"Sometimes when a bubble rises in the water cooler, I feel it attract my arm hair on the way up. Why? Diagram included."
] | [
false
] | [deleted] | [
"Will go to watercooler to test.\nEdit: Can't reproduce it."
] | [
"It's an ",
"autonomic response",
" which may be triggered by your visual observation of the bubble. Your nervous system can anticipate things, and something like a moving bubble near your arm could trigger that.",
"Do some science: for example, do you feel it when the bubble isn't in your field of view? Ho... | [
"Marginally relevant: ",
"http://xkcd.com/583/"
] |
[
"In an atom, why does a neutron change into a proton after the atom has emitted beta radiation"
] | [
false
] | In class today, my teacher said this to be true. She stated that after an Atom radiates an electron, the atoms proton number increases but the atomic mass stays the same. That's what she said but i don't quiet understand why that happens. | [
"By itself, it's a neutron turning into a proton, an electron, and a neutrino. The total mass of the end products is slightly less than the mass of the neutron, so it can happen without violating conservation of energy. Because it can happen, it eventually does.",
"The atomic mass doesn't stay the same, it chang... | [
"\"Why\" questions wont' really get you there. We don't know why particle decay happens - we only know that it DOES happen. Same with other types of radioactive decay, as well as the fundamental forces. They are just there - we can find out facts about them, statistics, things around them - but an underlying \"why\... | [
"As has been pointed out, the \"why\" is difficult to answer, but what happens ",
" the nucleons is roughly this:",
"Protons consist of two up quarks and one down quark; neutrons are two down, one up. The configuration of quarks in neutrons is not really stable but can be stabilised if there are enough protons ... |
[
"What happens to the mesons after annihilation?"
] | [
false
] | Do they eventually separate, collide with other quarks and form new hadrons, or do they just never react again? | [
"Could you clarify your question? You appear to be thinking of some particular process but I can't work out what it is. ",
"Do they eventually separate, collide with other quarks and form new hadrons",
"The quarks in a meson are bound by the strong force. There's no chance of them separating.",
"Also, the str... | [
"after the quarks and antiquarks separate, you end up with a number of mesons and a bunch of energy. ",
"Ah, you're referring to fragmentation/hadronisation in hard QCD scattering. This process isn't unique to particle-antiparticle annihilation. It occurs in proton-proton collisions, for example.",
"Plus you ca... | [
"Simply, there are more fundamental fermions than just quarks. There are leptons, too. (electron, muon, tau and their corresponding neutrinos)",
"Each of these has an antiparticle that they can annihilate with. Although it's possible that neutrinos are their own antiparticle.",
"There's even a ",
"whole wikip... |
[
"What happens to the stored energy?"
] | [
false
] | Experiment: An oil dielectric capacitor (used in RADAR transmitters and that resembles a large car battery) is charged and then the oil is drained into an identical but uncharged and empty oil dielectric capacitor. Question: Will the stored charge held in the dielectric move to the second capacitor? Or what happens to... | [
"It's the charge on the electrodes that maintains the electric field in the oil. When the oil is removed from its position between the electrodes, the field collapses and the stored electrical energy is transformed to thermal energy.",
"EDIT: To avoid confusion, let me emphasize that it's the field ",
" that co... | [
"Does the oil not simply act as a dielectric?"
] | [
"It does, exactly. (It may also serve to cool the device and/or suppress electrical breakdown by increasing the maximum field strength, but these are side points for this particular question, I would say.)"
] |
[
"If observation is the thing that makes reality rigid, how did the universe form itself in a time-linear fashion without any one there to observe it?"
] | [
false
] | null | [
"If we accept that the universe needs an observer for reality to become a 'solid' thing,",
"You should not accept this. Quantum mechanics does not depend on the existence of an observer. There are issues with explaining the origins of coherence and the measurement problem, but no widely accepted interpretation of... | [
"I understood particles behave differently without an observer? Like the double slit experiment proved?",
"So wouldn't the universe exist as nothing more than a probability cloud until consciousness was developed to witness it somehow? "
] | [
"The double slit experiment behaves differently if you put a measurement device so that it ",
" observation. IT has to do with the quantum mechanics of adding a new thing to the system makes a more complex quantum system. There is no way to add a device that could measure it without changing how it behaves. It d... |
[
"Is there a Gauss's Law for Light?"
] | [
false
] | If we state Gauss's Law as Can we say this? Does that equation hold true? I figured the dot product could go because illuminance is a scalar. Is there some other expression that it equals, such as Q/(epsilon_0) for Gauss's Law or 0 for his law for magnetism or mass for -4piGM for Gauss's Law for Gravity? tl;dr: I'm try... | [
"I think the differential form of Gauss' law is more instructive here. It says:",
"∇",
" = ρ(",
")/ε",
".",
"In general equations of this form say:",
"(divergence of vector field) = (source or sink).",
"Translated into words, the electric charge density is the source of electric field lines (source fo... | [
"Sure there is! if you consider a Ideal non existing point source. This is basically maxwells equation for a perfectly spherical wave. But again, each component of this (in the far field) can be described as a planar wave.",
"Check out feynman's Maxwell's equation chapter. Section 20-4 this is where my brain had ... | [
"but I believe the integral form still works?",
"In the integral form, you're calculating the flux of the vector field through some closed surface. It has to be a vector in either case. However the source density is a scalar.",
"Is there a vector version of illuminance or a version of Poynting's vector adjusted... |
[
"When Mars is moving away from Earth does it appear more red, or no because it doesn't emit it's own light?"
] | [
false
] | Enlighten me :) | [
"Contrary to what others have said, the doppler shift of light from Mars is entirely observable, though not with the naked eye. ",
"The fact that at certain points in its orbit Mars is moving away from or towards us fairly rapidly is used to enable ground based atmospheric spectroscopy - without the doppler shift... | [
"You mean ",
"red shift",
"? It's not nearly fast enough to see a red shift -- it has to be some significant fraction of the speed of light."
] | [
"Just fyi, If you're at rest relative to the sun, the maximum redshift of light from Mars would be .008%. So yeah, it's not noticeable."
] |
[
"Are Contact Lenses Slowly Killing My Eyes?"
] | [
false
] | Cornea seems to get oxygen from air and contact lenses sit between those. | [
"Undergrad research assistant here, working with a professor who studies the interaction between contact lenses, solution, and the eye. ",
"Basically, modern contact lenses and their solutions are designed to ensure as much oxygen as possible diffuses through to the cornea. Often, when choosing contact lens mater... | [
"Here's the skinny... You want contact lenses to transport as much O2 to your cornea as if it weren't there. Silicon Hydrogels offer the best O2 transport (Dk). Some of the hyper ones offer up to 125 Dk / T (look it up, such as Air Optix Night and Day, and some others), but they have a higher incidence of infilt... | [
"No. Contact lenses have existed for decades and have been used by millions and no problems regarding suffocated corneas have been reported. With same size that big if there was even the slightest chance of corneas being damaged due to lack of oxygen, it would have been discovered by now"
] |
[
"How accurately can medicine pinpoint causes of cancer?"
] | [
false
] | I'm a mechanic, and many products, chemicals and waste we handle everyday are known or suspected carcinogens. If, heaven forbid, I was diagnosed with cancer later in life, would these all be listed as "probable causes" for the cancer, or can medicine accurately confirm that a specific type of cancer is or is not caused... | [
"Cancer is when cells overgrow due to mutations in genes that affect the cell cycle, so cells start to reproduce and replicate without the controls. Control mechanisms within the cell cycle usually detect and repair bad DNA, and they make sure the cell doesn't reproduce at too high a rate, and they make sure that c... | [
"It very much depends on the type of cancer! For an easy example: if you develop mesothelioma and have a solid exposure history to asbestos, they will attribute it to that. For cervical cancer, we are pretty good at telling if it’s HPV-related or not.\nIf you get an odd cancer and have no other risk factors other t... | [
"Also note that far more things \"are known to cause cancer ",
"\" than anywhere else!",
"\nFor various interesting/historic reasons, California has exceptionally tight environmental restrictions (for pollutants etc), and one of the lowest thresholds for labeling products as \"suspected\" or \"known\" to cause ... |
[
"How do mRNA vaccines work?"
] | [
false
] | null | [
"mRNA encodes a protein. You get the mRNA into some cells, and they use this mRNA to make the protein. All cells send samples of every protein they're making onto their cell surface, for the immune system to keep an eye on what's going on inside of each cell. If you make the mRNA encode a protein belonging to somet... | [
"This is a tricky thing, your body does not know this \"foreign protein\" belongs to a virus or could be damaging to the body. It will express it on the surface of the cell, but not necessarily build an immune response to the expressed epitope(s). However, I am unsure how this could be properly done - usually a sec... | [
"Peptides from proteasome processes intracellular proteins are generally expressed on MHC class I, whereas endolysosomal peptides are expressed on MHC 2. ",
"All cells use the MHC class I pathway but generally only specialized antigen presenting cells use the MHC class II pathway. However, cells that express non-... |
[
"How does pressure on a bone help with the regrowth/healing process (in relation to osteoclasts)?"
] | [
false
] | I broke my foot (fracture of the lower third of the navicular) about 13 weeks ago. At this point, the Orthopedic Surgeon told me to start fully weight-bearing. He told me that weight-bearing would stimulate osteoclasts. I looked them up on wikipedia, and I didn't see anything about pressure stimulating their growth. | [
"Sure you don't mean osteocytes? Osteocytes (the cells that are enclosed in the bone tissue with collagen and minerals) have processes that are interconnected with each other. The processes carry mechanosensors that detect mechanical stress; activation of these sensors leads to various responses that overall increa... | [
"Are you sure you don't mean osteoblasts/osteocytes? These are the cells that live within osseous tissue that lay down the mineral framework of bone. Pressure helps to stimulate healing+bone formation and prevent bone resorption via osteoclasts (cells that secrete chemicals to destroy bone). From what I know, scler... | [
"just as a little addition, exercise in older people is also recommended to prevent the (physiological) loss of muscle tissue (sarcopenia). weight training seems to be the best method of accomplishing that. Also because of cardiovascular prevention. and prevention of diabetes. just to name a few things."
] |
[
"How come Titan has such a thick atmosphere, while Mars, being of similar size, could not maintain it?"
] | [
false
] | What caused one to keep it's atmosphere and the other to waste it away? | [
"It has to do with a few things.",
"1) Its low temperature. Because of this the molecules in its atmosphere move much slower and can't escape at a fast enough rate. If it were in our orbit it would lose its atmosphere from the increased sun exposure. This would heat the atmosphere allowing it to escape faster.",
... | [
"Ok, so lets take Venus vs Earth - similar size, it's closer to Sun (more exposed), much hotter, magnetic field is much weaker, yet atmospheric pressure is 90 times greater than the Earth's? It's like the exact opposite of your explanation.."
] | [
"There is no evidence that the magnetic field is a critical as people seem to think here. Earth (with a magnetic field) is actually losing more mass of atmosphere per unit time than is Venus (no magnetic field).",
"Venus's atmosphere is dominated by CO2, a heavy molecule; it is more difficult for heavy molecules ... |
[
"Polaris, the North Star, is .7 degrees off the Earth's axis of rotation (at present). Is there another star known to be spot on, but invisible to the naked eye?"
] | [
false
] | null | [
"There will never be a star that is spot-on for any period of time, since the exact celestial north pole is always moving, due to precession and other factors. That being said, there are always faint stars that are closer to the celestial north pole than Polaris. For example, HIP 3128 (mag 8.1, easily visible in bi... | [
"as ",
"/u/ben4808",
" said, the pole precesses, meaning it will trace out a circle in the sky or radius ~23°. Polaris will actually be closest to true north in the year 2100.",
"Some quick off-the-cuff calculations:\nThere are about 400 billion stars in the Milky Way, assuming an even distribution across the... | [
"The closest star ",
"in this catalog",
" to 90º declination is at Dec 89.9824, which is 1.05 arcminutes off. A circle centered on the north pole with this star on the edge would take up only about 1/43 millionth of the sky. It is apparently 19th magnitude, so you would need a damn good telescope to see it.",... |
[
"3 Body-Problems with Asteroidal orbits"
] | [
false
] | So I remember from physics that a problem involving determining the gravitational interactions between 3 bodies is impossible to calculate, but this .gif shows the path of the asteroid, Earth and the Moon. Are they rounding, or making some sorta of estimation? Or is it possible to solve a 3-body problem? | [
"There is no \"closed form\" solution to the 3-body problem. This means that you can't solve the equation of motion analytically to get an answer in terms of other functions like sin, cos, e, x, x",
" , etc. ",
"Any solution that you get is done numerically. That is, you basically cut up your problem into ti... | [
"So help me understand something. The n-body problem is basically that you can't input arbitrary initial conditions, apply a formula, and have it spit out the state of the system at an arbitrary time in the future. Instead, you have to run a simulation incrementally for x number of steps and see what the simulation... | [
"That really just gets you back to the 2-body problem."
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.