title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"If a flashlight was on and free floating in space would it accelerate?"
] | [
false
] | Would the emission of photos push the flashlight at all? | [
"Would the emission of photos push the flashlight at all?",
" Yes. ",
"Photons carry momentum, which would cause the flashlight to experience a force against the direction it was shining.",
" let's go an adventure. For a normal pocket flashlight powered by a single 1.5 Volt AA lithium battery, we can do an ea... | [
"Sure, a one liner is possible, but where's the fun in that?"
] | [
"I thought the momentum was calculated by mass*velocity ",
"p = mv is a classical, Newtonian equation. In Einsteinian relativity, E",
" = m",
" c",
" + p",
" c",
" - this looks familiar for an at rest particle, it reduces to E = m c",
"Anyway, if you plug in m=0 for a massless particle, you'll get E =... |
[
"What causes food to start tasting bad when it gets burned?"
] | [
false
] | null | [
"The proteins become denatured, sugars caramelize. In many foods, these actions are intended and add to the complex flavors. Think of a perfectly grilled steak.",
"With severe charring, many of molecules are reduced to carbon/charcoal. While likely not toxic, it can rob food of its flavor. The carbon could eve... | [
"This person is right. I'd like to add that some foods that are burnt can become carcinogenic and dangerous for consumption."
] | [
"I mean, they'll tell you that anywhere, it's true. Doesn't stop me doing it."
] |
[
"It is believed that time behaves differently near massive objects like black holes or earth. This theory is proved by measuring the time at the bottom and top of a tower. How did they measure time in this case?"
] | [
false
] | Let's say we used a smart watch, will being at different places change how the software calculates a second? | [
"No we definitely know, it’s just hard to come up with an ",
" explanation for a general audience"
] | [
"You seem to be thinking of ",
"this",
" experiment. Have a read and ask any follow ups here"
] | [
"The cause of the redshift IS time dilation though. I'm struggling to come up with an intuitive explanation of this, give me a while",
"Edit: don't know why that failed to post at first. How does this explanation work for you?",
"Imagine we have two observers (A and B), separated by a constant distance. A turns... |
[
"What are the implications of high vs. low (or vs. medium) metallicity in stars?"
] | [
false
] | [deleted] | [
"As stars evolve, they create heavy metals in their core, so that stars created now have higher metal content than stars created billions of years ago. So a star with very low metallicity is a very old star, and studying such stars can tell us a lot about star formation and such earlier in the Universe."
] | [
"In general, metallicity is inversely related to age. Older stars have lower metallicity, younger stars have higher. ",
", it just provides us some information about the star's history."
] | [
"Metallicity can make quite a difference for high mass stellar evolution. More metallicity = more radiatively driven solar winds = more mass loss. This could determine, for example, whether you end up as a black hole or a neutron star."
] |
[
"Is there any (conceivable) technology capable of generating topsoil on a massive scale?"
] | [
false
] | We won't be able to adapt to climate change by just cultivating the Yukon instead of Iowa--there's hardly any topsoil in Northern Canada & Siberia. We won't be able to grow corn up there for a long time. So is there any technologic solution for speeding up / seeding the generation of a layer of topsoil in the warming s... | [
"You're going to need a lot of shit. (Sorry, it was too hard to pass up.)",
"Seriously though, top soil is mostly just decayed organic matter. It's mostly decayed plant material, but manure can help too. It's also \"alive\" in that there's significant insect and plant disturbance (roots) which helps to aerate it.... | [
"You can 'farm' topsoil, but it takes time. If you have bare soil you can grow certain types of crops/plants and increase the organic content of the soil. See this youtube video (skip the ad in front) to give you an idea of what is done:\n",
"http://www.youtube.com/watch?v=qi6AroLfZS8"
] | [
"Additionally, wouldn't it not even matter if you moved all that soil if the conditions weren't right to keep it there? I could easily see all that soil eroding away from steep slopes and lots of rain. Iowa is flat while the Yukon is not. ",
"From what I understand, it would take a long time to develop a producti... |
[
"Are our pinky and ring fingers mechanically linked?"
] | [
false
] | I can put my ring finger down by itself, no problem. But whenever I try to put my pinky down, the ring finger wants to come along with it. Why is that? How come it doesn't work vice versa? | [
"The tendons that go to these fingers are attached to the same muscle (FDS, FDP). With the tendons being adjacent to one another, it makes it difficult to flex one tendon/finger via muscle contraction while keeping the other tendon/finger completely extended. You are literally contracting one part of the muscle whi... | [
"So the image you linked is for ",
". Innervation neurons are sensory neurons. Ennervating neurons are those responsible for doing things like moving a muscle. Dermatomes refer to which ",
" neuron is responsible for carrying sensory information from the extremity to the brain (or spinal cord). Your diagram... | [
"Hmm. I have played multiple instruments, including piano, and I still have the same situation with my ring and pinky fingers as the op describes. "
] |
[
"Why did life began ?"
] | [
false
] | null | [
"How is it possible that life began in this universe, when all things in it tends to be in lower energy state?",
"Whatever rule you think exists here, you're wrong. 'Tend to' is not the same as 'must be in at all times'.",
"You're probably referring to the second law of thermodynamics, which tells you how a clo... | [
"Ah, That makes perfect sence :). so simple when you know what entropy is. But this raises 2 questions in me:",
"1) Can we consider whole universe as closed system ? Does it mean then that there will be time when universe will be like only one homogenous matter/energy ?",
"2) How did unorganic molecules starte... | [
"1) Can we consider whole universe as closed system ? Does it mean then that there will be time when universe will be like only one homogenous matter/energy ?",
"I'm not sure whether the universe fits into the closed system definition. However, we certainly do expect an entropy increase ultimately leading to ",
... |
[
"Are the planets really in a ring around the sun?"
] | [
false
] | [deleted] | [
"Yes, the planets orbit the Sun on the same plane, more or less. ",
"This question has been answered before. Be sure to check out the ",
"FAQ's",
" next time. Quoting my answer from the FAQ's on this subject:",
"The reason is the physical principle known as conservation of angular momentum.",
"Before the ... | [
"Expact of Triton, one of Neptunes moons. He roates against the Spin of Neptune."
] | [
"And Venus spins the wrong way. And Uranus is sideways.",
"We think that those moons that go the wrong way are actually captured asteroids."
] |
[
"How/does light slow down?"
] | [
false
] | I've learned in Physics about how different materials have different refractive indexes, and part of the explanation was that the light "slowed down". I've heard or read other explanations that involve a "group velocity" and state the light doesn't actually slow down but appears to. Can someone explain how light slow... | [
"This is false, and a common misconception.",
"From the QM photon model, the change in speed is due to taking the path integral of all possible paths the photon can take through the substance, and then the net effect of the suboptimal paths combines with the the optimal path at c through the substance combines ge... | [
"Here is a Sixty Symbols youtube video explaining why the common idea of photons \"bouncing around\" like pinballs inside matter is wrong:\n",
"https://www.youtube.com/watch?v=CiHN0ZWE5bk",
"There are more appropriate models.",
"Classically: Light is an EM wave. Inside matter, the macroscopic view is that the... | [
"Thanks for the explanation! Follow up question: If the light is being absorbed and re-emitted, wouldn't that mean that different wavelengths would be absorbed and re-emitted differently? Wouldn't this cause different refractive indexes for different wavelengths of light?"
] |
[
"[Biology] Is it theoretically possible for a human to stop producing digestive waste?"
] | [
false
] | If such a food existed that only gave the body exactly what it needed, could humans stop urination or defecation? | [
"Not defecation. Besides food, feces contains bilirubin which is made from destroyed red blood cells. You need to be able to excrete bilirubin, otherwise you'd get hepatitis and jaundice. The urine excretes like 5% of the bilirubin (which makes your urine dark btw), but it's incapable of handling all the bilirubin.... | [
"In addition to the bilirubin, your body uses bile secretion (the stuff that comes out of your gallbladder) to excrete some other stuff it can't get rid of in urine. Your GI tract also sheds dead cells from the surface lining, and additionally has lots of bacteria living in it that excrete, die, etc. Even if you ... | [
"Relevant: a ",
"severely obese man fasted for over a year under medical supervision",
". During the fast, he defecated roughly every 40-50 days, despite consuming no solids. "
] |
[
"Do neutrinos interact with superfluids more often than they interact with other states of matter?"
] | [
false
] | Do neutrinos interact with superfluids more often than they interact with other states of matter? | [
"They are not expected to. There were proposals in the superfluid helium as a detector medium, not because of enhanced interactions but because the interactions that did occur might be easier to detect. However, I don't think such a detector was ever implemented.",
"May I ask what prompted this question?",
"htt... | [
"Ah. That's a bit less understood. I think in that situation, it wouldn't necessarily be the superfluidity, but the extreme density of particles that would increase the interactions. The superfluidity might lead to some interesting correlations though."
] | [
"Thank you for the reply, info, and link. ",
"May I ask what prompted this question?",
"Certainly. I had read an article that proposed some Neutron stars may have a superfluid core. If true, this dense core seems to me like an excellent location for Neutrino interactions to take place. Which led me to question ... |
[
"Does laminar flow occur more easily in a fluid with a higher viscosity?"
] | [
false
] | null | [
"Yes, the ",
"Reynolds number",
" (Re) is a dimensionless quantity that is used to characterize the transition from laminar to turbulent flow in fluids, where low Re is laminar and high Re is turbulent. There are a few ways you can write it out, but it's basically the ratio of flow rate to viscosity, so a fluid... | [
"Agreed. But there are some exceptions! Viscoplastic fluids like toothpaste could conceivably start off as having a higher effective viscosity, but then become thinner as shear rate increases. The same applies when comparing shear thinning, shear thickening, or thixotropic fluids. Basically in all these cases visco... | [
"Yeah the ideal case is a linear relationship between shear stress and shear rate but everything deviates from that at some point"
] |
[
"Super Conductor Wire + Breaking Thermal Laws?"
] | [
false
] | I was reading an article about room temperature superconducting materials, and the long term dream/goal of changing our electrical grids to superconducting material. This of course would remove all our waste energy during transfer. Which got me thinking. If you had a power plant on one side of the planet, and you trans... | [
"nope, superconductors have exactly 0 resistance below their critical temperature."
] | [
"I suspect that a room temperature superconductor (if even possible) would contain vortices (pools of non-superconducting material). It wouldn't perfectly super-conduct in all regions and there would be some heat loss, overall entropy would be created. Also, most superconductors can only handle a certain amount of ... | [
"This of course would remove all our waste energy during transfer.",
"It would remove resistive waste, but not radiative waste. "
] |
[
"Newton's Cradle (the 5 metal pendulums swinging and hitting each other) is supposed to show conservation of momentum, but isn't it broken when it swings backwards?"
] | [
false
] | [deleted] | [
"Momentum is conserved only when there are no external forces. In the case of a pendulum, the force of gravity changes the momentum of the ball.",
"Newton's cradle demonstrates conservation of momentum in collisions."
] | [
"I always thought Newton's cradles were supposed to show conservation of energy. It wouldn't make sense to use them to demonstrate conservation of momentum, because they ",
" conserve momentum. Gravity is an external force acting on the system."
] | [
"It shows conservation of momentum of the interactions between balls. If you drop n balls from one end you always get n balls flying away at the other end."
] |
[
"I have an atom with an excited electron. A mile in every direction are cameras pointing towards the atom. The excited electron drops orbit and one photon is emitted. Who gets the photon on film? Can it register on all the cameras?"
] | [
false
] | [deleted] | [
"The photon could be detected in any direction (only one), according to some angular distribution. Unless the atom is initially polarized, the distribution is uniform over all angles."
] | [
"It's emitted in all directions. The measurement device collapses the state to within the solid angle subtended by the detector, if it's detected."
] | [
"What you've basically described is called the ",
"Mott problem",
"; the output of the formalism that is quantum mechanics is a quantum wave-function, whose square is the ",
" of a certain event. In general, in such a scenario, the probability would be equally likely in all directions and the wave-function wo... |
[
"If there are rogue planets, does that mean there could, theoretically, be rogue solar systems?"
] | [
false
] | As in, solar systems hurtling through space not in the gravity well of a galaxy? Would life be affected in any way if this were a thing that existed? For instance if the Sol system were to become one of these “rogue systems”, would we even notice (apart from a drastically reduced amount of stars in the night sky I’m as... | [
"So we know that when galaxies collide, some stars are thrown into intergalactic space. Not all of them are going to take their planetary system with them, but not all of them won't, either. ",
"The second question is more interesting to me, would it make a difference? I guess it depends on when we left the ga... | [
"There would be no stars in the sky. Only starts within about 3k light years can be seen with our eyes. So it would be a pure black night.",
"A good and bad aspect for life on such a system would be that it would avoid risk of annihilation by nearby super nova. That is a serious risk to planets nearer our Galaxy ... | [
"Though you are right about stars, we can see the Andromeda Galaxy 2.5 million light years away. The galaxy the rogue system left would probably be visible."
] |
[
"How does a hair dryer infuse Keratin into your hair? Link in text."
] | [
false
] | [deleted] | [
"Since the ring \"lasts the life of the product,\" clearly it gives off very small amounts of keratin. Therefore this appears to be marketing silliness rather than a serious benefit."
] | [
"Yeah that's what I'm thinking too, I guess the more important question to ask is whether blasting Keratin at your hair @ 100mph actually somehow cause your hair to improve in quality. Could I take 1 KG of Keratin and hurl it at my gf's head, would she get shiny hair?"
] | [
"I would say that the \"keratin ring\" is just a stupid piece of plastic. If it was giving off keratin somehow, they would have to liberate it from the plastic somehow, probably with heat, which would make the whole room smell like a barbershop on fire. "
] |
[
"Why do electrical appliances always hum/buzz at a g pitch?"
] | [
false
] | I always hear this from appliances in my house. Edit: I am in Europe, for those wondering. | [
"It's because the frequency of the AC current in your house is 50-60Hz (depending on where you live). When this AC current runs through a transformer in your appliances, it causes the iron core to expand and contract ",
"through an effect known as magnetostriction",
". This expansion and contraction happens at ... | [
"Just to piggyback on this, the hum frequency is usually twice the AC frequency (so, 120 Hz in the US). This is because the magnetostriction intensity is proportional to the magnitude of the magnetic field and not its direction.",
"https://en.wikipedia.org/wiki/Mains_hum"
] | [
"https://en.m.wikipedia.org/wiki/G_(musical_note)#:~:text=As%20such%20it%20is%20the,note%20is%20approximately%20391.995%20Hz.&text=(a%20diatonic%20semitone%20above%20G%E2%99%AD",
"A G is 391.995 hz, and if you drop down a couple octaves, you get 49hz, so I'm curious to know if OP's power is 50hz"
] |
[
"Why do so many men in their 50's develop a hard 8-months-pregnant-like belly?"
] | [
false
] | null | [
"The ",
"Wikipedia article",
" on abdominal obesity has a pretty good description, which I'll paraphrase: As men age, their metabolisms slow down; this results in a net energy imbalance that causes them to store extra energy as fat. Male hormones cause men to typically store extra fat in their bellies, while wo... | [
"Well, most people who have abdominal obesity also have a fair amount of ",
"subcutaneous fat",
", too. This isn't my specialty, but I am not sure you'd really see someone with a \"six-pack belly,\" unless it was in odd circumstances."
] | [
"Please give evidence for this impacted fecal matter. If it really did build up on the interior of the intestines, they would be less flexible due to the built up layer of old shit, would it not? Also, nutrient and water absorption would be severely limited due to the wall of shit coating the inside of the colon an... |
[
"The blood-brain barrier: what does it 'let through', and what does it 'stop' from reaching your brain?"
] | [
false
] | [deleted] | [
"An example is opioids/opiates. Hydrocodone, Oxycodone, Morphine, etc. can all pass the blood-brain barrier.",
"An over-the-counter opioid (the only one in America as far as I know), Immodium (for diarrhea) is an opioid also, but it doesn't make you \"high\" because it can't cross the blood-brain barrier.",
"It... | [
"It doesn't really prevent bacteria passing into your brain - meningitis or cerebral abscesses are often caused by bloodstream infections for example. In fact in meningitis, the blood brain barrier becomes more leaky, and lets through drugs that it normally would block; rather handily this includes some of the anti... | [
"I thought it wasn't actually glial cells creating the physical barrier, but rather the astrocytes (glial cells) inducing the epithelial cells of blood vessels to form tight junctions around the blood vessel. Thus the only thing that can exit the blood vessels and capillaries and enter neural tissue are things that... |
[
"How does the International Space Station compensate for orbital decay?"
] | [
false
] | Since the International Space Station is in the thermosphere, it must be affected by some sort of friction. This drag must affect the angular momentum of the ISS. If the orbit of the ISS is decaying each period it completes around the Earth, how do space agencies correct this? | [
"https://blogs.nasa.gov/spacestation/tag/reboost/",
"\"A reboost of the International Space Station using the Russian Progress 58 cargo craft was completed successfully on Sunday at 7:30 p.m. CDT. A previous attempt on Friday evening was aborted one second into the burn automatically by the Progress vehicle. Russ... | [
"If you like that you should love \"night glider mode\".",
"https://wikivisually.com/wiki/Night_Glider_mode",
""
] | [
"Wow! Fascinating! That is awesome how they restore the angular momentum! Thank you! "
] |
[
"What is the purpose of a biological library?"
] | [
false
] | I've heard the term before in reference to cDNA libraries and genomic libraries, but I don't fully understand what it is or its purpose. Can someone explain it please? | [
"A cDNA library is just cloned complimentary DNA that has been incorporated into one or more \"host\" bacterial plasimids. The bacteria serve to replicate the plasmid(s), therefore \"amplifying\" the clone (\"amplification\" is just a word meaning \"making several copies\"). This is a handy way to take an interes... | [
"A cDNA library is all of a cell's RNA converted over to DNA by reverse transcriptase. We do this because RNA is a bitch and a half to work with - PCR doesn't work on it directly, it degrades if you look at it funny, it's difficult to reliably cut, and can't easily be transferred to other organisms. The other benef... | [
"cDNA refers to complementary DNA of a cell. This DNA contains the active or expressed genes. Understanding this sequence and genes of a cell narrows down what the essential genes are for the cellular life. The purpose of this is not only understand the cellular functions, but to be able to create pathways in a ... |
[
"Massively decreasing entropy (also Asimov's \"The Last Question\")"
] | [
false
] | [deleted] | [
"The entropy of a black hole is proportional to the area of its event horizon. Thus, when a black hole takes in matter, the entropy is not decreased.",
"Edit: There's a nice article on this at ",
"Scholarpedia",
" that gives both non-technical and technical perspectives on black hole entropy."
] | [
"Although it's completely unintuitive, it is believed that ",
"black holes actually carry entropy",
" and that, in fact, they have the maximum amount of entropy per unit volume. ",
"This gets very quickly into a very subtle area of modern physics research, but I think it answers your question to say that cre... | [
"I don't think it's really unintuitive that black holes carry entropy, though the fact that their entropy is proportional to area is superficially surprising. Entropy is a measure of how many micro states correspond to a given macro state. Given that a black hole in general relativity is the epitome of a macro st... |
[
"How does peeling scotch tape in a vacuum produce x-rays?"
] | [
false
] | Title. | [
"the term you are talking about is \"",
"triboluminescence",
"\" but i cant not find any article that tell why it produces x-rays only while in a vacuum and not while in air, my best guess would be you are separating electrons layers when the tape is pulled apart creating the x-ray but i have not proof to confi... | [
"The mechanism of tribuluminescence isn't generally agreed upon but one common suggestion is separation of charges that emit radiation when they recombine. So your best guess is pretty close (probably)."
] | [
"I use Breathe Right strips. The individual strips come wrapped in paper with adhesive around the edges. When I peel the paper apart in the dark, there's a distinct subtle light emitted where the adhesive is located. I always thought it was strange to see light coming from this. Does it sound like this is tribo... |
[
"Question regarding optic nerves, and nerves in general."
] | [
false
] | [deleted] | [
"I just wanted to point out that some nerves do have the capacity to regenerate after damage. Peripheral nerves that innervate the extremities can regenerate and can also be reattached in surgical reimplantations of amputated limbs and fingers. There also have been hand transplants that involve reconnecting the ner... | [
"There's an important distinction to make in this discussion. Peripheral neurons (those outside if the brain/spinal cord that supply your muscles and skin) can regrow. Central neurons (those inside the brain/spinal cord) can't. It is currently believed that all neurons have the capacity to regrow, but their externa... | [
"From what I can see, in ",
"hereditary optic neuropathies",
" the retinal neurons develop properly and wire correctly with their targets in the brain, but later (in childhood or adolescence) they die."
] |
[
"When your body is a fighting a virus, is it fighting it in one place or all over your body?"
] | [
false
] | Are battle lines drawn? Or is it total war, with guerrilla warfare? Or is a battle metaphor unsuitable? | [
"I can tell you that that is not a good metaphor because most viruses aren't capable of fighting back against the immune system so it isn't really a battle. The immune system actually is in some ways more like a pest control service.",
"To answer your question, it really depends on what kind of virus it is. Viru... | [
"Your immune system is also producing pro-inflammatory cytokines that may not be confined to the area of infection."
] | [
"Ok, so right now I have what I assume is a common cold. My throat is swollen, I am coughing and lethargic.",
"So the situation could be that cells in my throat are the ones being attacked by this virus, which is causing the swollen throat and cough. Then my body is diverting blood cells to tackle this virus, lea... |
[
"Does dark energy do anything else besides cause the universe to expand?"
] | [
false
] | I recently finished an introductory astronomy course and the last thing we learned about was the expansion of the universe and dark energy's role. My question is if dark energy is thought to be involved with any other processes in the universe, or as far as we can tell, is it's only effect the expansion of the universe... | [
"I am by no means an expert on the subject, but I also just finished an astronomy course and I would like to share my understanding and be corrected if I'm wrong.",
"From what I understand, dark energy has two effects. One is the expansion as you said and the other is simply adding mass-energy to spacetime, which... | [
"What you say isn't particularly wrong but it's slightly misleading. The flatness and homogeneity we observe today is most popularly contributed to ",
", a period of rapid and exponential expansion in the early universe. The accelerating expansion of our universe today is contributed to dark energy. The two thing... | [
"Please keep in mind that 'Dark Energy' like 'Dark Matter' is our term \nfor something we don't yet clearly understand.",
"The Universe appears to be expanding at an accelerating rate.",
"Matter seems to 'clump' in the locations of the galaxies.",
"We quantify these observed effects and assign Energy and Mass... |
[
"Why do or lips go blue when whe get cold?"
] | [
false
] | null | [
"Why blue? Why not pink or black?"
] | [
"The blood vessels in your skin constrict or narrow in cold surroundings, this reduces the amount of heat lost through your skin in an attempt to maintain your internal temperature. Because of this the skin receives less blood and turns a bluish hue. The opposite will happen in warm surroundings, so the blood ves... | [
"It is an optical illusion. When the skin constricts when you are cold the capillaries in the skin do not contain as much oxygenated blood.... which is red. This does not mean they turn blue when there is no oxegen... it just means they are not emitting red. We see blue because the skin does not absorb the blueish ... |
[
"Is There a Name For the Area Immediately Outside a Planet's Atmosphere"
] | [
false
] | For example, when we talk about things airplanes flying over a particular area, we call it "airspace": "Now entering North Korean airspace." For boats, it's either "territory" or "waters": "Now entering North Korean waters." Do we have a name for the area just beyond a planet's atmosphere? Like if we ever get to Mars... | [
"Probably either ",
"exosphere",
" or ",
"sphere if influence",
" would be the best terms (although the latter would also include things inside the atmosphere proper, so that might not be what you're looking for)."
] | [
"Considering that the planet's atmosphere never really ends, just becomes thinner and thinner until it's indistinguishable from interplanetary space, ",
"exosphere",
" is probably the closest thing to what you are describing."
] | [
"600km? Is that right? So all of Earth's satellites—artificial and natural—are actually inside the \"thermosphere\"?",
"Okay. Exosphere it is. Thanks for the info."
] |
[
"How do scientists find certain things out?"
] | [
false
] | null | [
"When it comes to things that happened in the distant past, we look at other phenomenon happening at the time. For example, to find the CO2 content of the air in 1400, we take what are called ice cores - long cylinders of ice we drill out of the polar caps. We can look at the ice that was laid down in 1400 AD, an... | [
"Thank you. Quick question, though, and I know they are scale numbers, but, how do the scientists know the original weight of said element? "
] | [
"Well, you add the current weight plus the weight of the decay products and you get the original weight."
] |
[
"LIGO/VIRGO Gravitational Wave Megathread"
] | [
false
] | Hi everyone! We have an announcement from the LIGO/VIRGO collaborations starting at 12:30 ET (1630 UT). We'll make sure to keep you up to date as the news comes out. Ask your gravitational wave (GW) questions here! Announcement streams: Useful links: EDIT: It's a joint LIGO and VIRGO detection! This adds even more cred... | [
"Here's a very quick summary of the new science reported today, and what it means for the future of gravitational wave astronomy. ",
"This event, ",
"GW170814",
" is similar to the three events seen before. The black hole masses are in the 20-30 solar mass range. ",
"The remarkable thing today is that this ... | [
"Yes. The 'speed of light' is just the speed at which massless particles/waves travel. We only call it the speed of ",
" because light was the first thing we discovered that travels at this speed, and is still the most familiar."
] | [
"Do gravitational waves travel at the speed of light?"
] |
[
"Exactly what property of a quark is being described by its \"color?\""
] | [
false
] | [deleted] | [
"Exactly what property of a quark is being described by its \"color?\"",
"Color is its own unique quantum property, similar to electric charge or spin. As you mentioned, it is not related to the human perception phenomenon \"color.\" Color as it applies to quarks can be distinguished as \"color charge\" as it i... | [
"Strongly-interacting particles are ",
"confined",
" so that all naturally-occuring particles must have a net color of \"white\".",
"Also at very high energies, when strongly-interacting particles scatter off of one another, they ",
"polarize the vacuum",
" in a way which anti-screens their interactions. ... | [
"It's just a simplified way of thinking about combining quarks into bound states. You can have a red, green, and a blue, making a \"white\" baryon, or you can have a red and antired, making a meson. (Also others like antired, antiblue, antigreen; green, antigreen; etc.)"
] |
[
"Why do we need mRNA?"
] | [
false
] | [deleted] | [
"One advantage is that mRNA is short-lived, permitting regulation. You would not really want a lot of DNAse running around the cell lest it destroy or damage your master copy. Neither would you want production of a given protein to run flat-out without a way of shutting it off."
] | [
"A lot of questions to unpack there but the main thing to know is that DNA can’t leave the nucleus. Entry/exit from the nucleus is very strictly controlled because the cell wants to protect the DNA from anything harmful. ",
"There are actually 92 strands of DNA in a human cell. Each cell has 23 pairs of chromosom... | [
"So we've established that RNA can do a lot of tasks on its own, but our cells have a lot more than just RNA. So why do we have a system of DNA-->RNA-->Protein?",
"As stated before, we only have 2 copies of each strand of DNA, and they're all precious. It's worth noting that we don't have one copy as a primary DN... |
[
"Why can't programmers figure out the source code or basic algorithm of a program based on the machine code?"
] | [
false
] | Why can't we translate machine code back into a human readable medium? | [
"You can, kind of. The problem is that when you go between layers of abstraction things (like variable names and notes) won't be recovered. ",
"For example. Say I have a bit of code for something to do with population analysis, and I have variables in my source code labeled Chicago_pop_2014 and Chicago_pop_2013. ... | [
"It's a question of entropy - the compiled doesn't all the details that went into making it. Recovering the human readable and understandable concepts and organization that went into a piece of machine code would be like trying to extract the original scripts, shot list, notes, cues and artwork from a finished and... | [
"In addition to what everyone else said, I want to mention ",
". The goal in any program is (or should be) to make the code understandable to other engineers. Or even to yourself if you have to read the code 6 months later. The goal for a compiler is to make the resulting machine code run fast. Often this comes a... |
[
"Have humans always been repulsed by the smell of sweat and other body odors?"
] | [
false
] | I was wondering, what people did before there were cleaning agents(ie.deodorant and bodywash)? Have we been socialized to think that these smells are foul? Or is it a natural reaction to the smell? EDIT: Thank you so much for all the responses guys, thank you for confirming my hunch about the issue. Finally, thank you ... | [
"Actually, some evidence shows that it is quite the opposite. The opposite sex is often attracted to a certain level of smelliness, as they are also getting a whiff of hormones and pheromones along with the stench."
] | [
"This is true. There have been studies done on this (I'm away from my computer and will post them when I can). It's believed that it has to do with Major histocompatibility complex (MHC) genes. They're used in differentiating self from non self. It's believed that people prefer the smell of others that have opposit... | [
"In Elizabethan times, ladies would peel apples, carry them around in their armpits for a few days, and then give them to their favored suitors. The apples would absorb their odors (which, given the time period, were potent), and the lovestruck gentlemen could sit around, sniffing the thing for a couple of days."
... |
[
"Is there an intuitive explanation for why C^2 is the ratio between mass and energy?"
] | [
false
] | E = mc I have a background in physics, but I never got a good handle on relativity. Is there an intuitive explanation, or are there any theories which address C seems to be this magic ratio number? For example, C can be thought of as the speed limit for information in the universe... but what I can't comprehend is what... | [
"Are you familiar with four-vectors? I find they help give you an understanding.",
"First, you have to realize that the fact that we measure distance and time with different units is an accident of history and we really should never have done so. In special relativity you have a four-vector to represent a positio... | [
"The fact that there is a c",
" is there is just to convert something with units of seconds into units of meters so that all the numbers can be sensibly added together. So first forget that the value of c is really of fundamental importance at all, because all it does is converts seconds to meters.",
"Be carefu... | [
"This is a quite well done explanation! It's also worth noting, just because it's interesting (at least I think so), the brilliance that is natural units, specifically Planck units. We normally use meters, kilograms, and seconds to measure length, mass, and time in physics. But it turns out that humankind isn't exa... |
[
"Because corn is not perfectly digested by humans, it can be found in feces. What would happen if one ate only corn for an extended period of time? How would it affect his/her digestive system?"
] | [
false
] | [deleted] | [
"In a really weird way....your friend preformed a science experiment. He can proudly call himself a scientist."
] | [
"In a really weird way....your friend preformed a science experiment. He can proudly call himself a scientist."
] | [
"I dunno. Corn's pretty good. You'd need a protein source (Such as beans.) but you could survive a long time on corn alone."
] |
[
"If you attempt something that has an infinitely small probability and infinite number of times will you ever succeed?"
] | [
false
] | I realize it's more mathematical than hard science but I'm sure you guys could appreciate the conundrum I have. From the thread on two babies being born at the same time. "If you split a second enough the chances of two babies being born at the exact same time approaches 0" But what if you had an infinite number of bab... | [
"What you are describing is an event whose probability is ",
"measure 0",
".",
"If you try to counterbalance the infintesimal probability with an infinite number of events, you end up with an indeterminate form, the resolution of which depends on the specifics of how you are defining the infinities. The prob... | [
"This question can be answered by someone who took Calculus I. Try asking a friend of yours majoring in math, or engineering.",
"What you are basically asking is:",
"The answer is: DEPENDS",
"Lemme explain in a ELI5 manner.",
"First things first, you cannot multiply zero with infinite. Infinite is not a num... | [
"No, it doesn't approach ",
" 0 and 1. It approaches ",
" 0 or 1 (or some other number in between).",
"As rlee89 said, what the probability approaches depends on how you define the infinities."
] |
[
"Did caffeine evolve independently in various plants or do all caffeine-containing plants have a common ancestor?"
] | [
false
] | null | [
"I think the best way to answer this question would be to map the trait on a phylogenetic tree and look at the parsimony of each hypothesis. A phylogenetic tree maps the evolutionary relationships of various related species, and phylogenetic parsimony means that the fewest changes would be the best hypothesis; it's... | [
"The plants probably aren't developing the gene from a blank slate. Caffeine is similar to other common, naturally occurring molecules, like guanine. All the plants in the tree may have some enzyme that converts a molecule similar to the precursor of caffeine into something else similar to caffeine (say, by methyla... | [
"I'm ignorant, why this is heuristic symmetric? Wouldn't the chance of losing a specific gene, that's already present, be much greater than the chance of redeveloping it, from a blank slate?",
"Since the number of genes in a genome is small, and the number of potential genes to develop is combinatorially large."
... |
[
"Why does seeing somebody else get injured (broken leg for example) make us cringe or even physically sick?"
] | [
false
] | Experienced this first hand today and remembered hearing about teammates of a player who broke his leg vomiting after seeing the leg snap. Is there an explanationo why this happen? Are certain people more prone to experiencing this? I'm not even sure if I should tag this under Medicine or Psychology, so maybe the mods ... | [
"Now, I'm only a student taking a psychology course, but I believe I can answer this for you. ",
"Mirror neurons",
" are a type of nerve that fire both when we do an action and when we see an action. They are how we have empathy and allow us connect with those around us. We feel ill at the idea of harming our b... | [
"What you are describing is the vasovagal response. Basically what happens is a trigger causes a gross shift in parasympathetic tone over sympathetic tone. If you aren't aware of the sympathetic and parasympathetic nervous systems, the sympathetic nervous system serves to ready the body to deal with stress (heart r... | [
"First off, thank you for your input! That does sound reasonable, but I don't think it quite explains why we feel sick seeing it. I saw a guy blow out his knee today and I literally was on the verge of throwing up (the scene has also been replaying in my head for the past few hours over and over again), yet I have ... |
[
"If we cloned a mammoth, would that mammoth and all resulting mammoths that spawned from that mammoth have extremely short lifespans due to telomere length?"
] | [
false
] | I am fairly certain that if mammoths were to be cloned, the first one would be crippled age wise, but would offspring of that mammoth have full telomeres? | [
"According to this ",
"textbook",
" at least one of Dolly's offsprings showed no significant telomere shortening. So my guess is this would happen with the mammoths as well."
] | [
"It would all depend on where they got the DNA from. If they so happen to find a intact child mammoth then the telomeric shortening should be less of an issue.",
"Dolly's issues arose from using adult sheep DNA to clone from...DNA that had its telomeres already shortened by general aging and replication."
] | [
"Disclaimer: I don't study embryology or developmental biology. ",
"With that said, I really doubt it... telomerase is highly expressed in germ line cells, embryonic tissue, most tumor cells, and pretty much any cell that needs to escape the loss of material after each cell cycle. It's likely that the telomerase ... |
[
"Why is tension independent of an object's length whereas compression is not?"
] | [
false
] | Hi guys. In my physics class today we did some compression and tension tests on materials and found that the change in length of a straight piece of wood changed how much compressive force you could apply to it before it broke. The longer pieces of wood could take less compressive force before snapping. Conversely, we ... | [
"compression causes a failure through buckling, and length affects that for the same reason it's easier for you to bend a longer object. ",
"Tension meanwhile causes failures through snapping and the force literally rips the object apart somewhere. the force required to do that will be fairly consistent "
] | [
"When testing timber under compression, you are really testing it's resistance to bending. A longer piece of timber is easier to bend, so snaps first.",
"If you did something to prevent bending, then you would find that compression is also independent of length."
] | [
"basically yea. Compressive strength is independent of length, that's completely correct, however when something fails due to buckling, elasticity determines the critical load not the compressive strength of the material. It failing for a different reason. If you managed to reinforce it or otherwise prevent it from... |
[
"As CO2 concentrations increase and temperatures rise, will the temperature at which C3 carbon fixation is in equilibrium with photorespiration rise more or less than ambient temperature (average)?"
] | [
false
] | With increasing global temperatures and increasing CO2 concentrations, there seem to be two contrary effects on C3 photosynthesis: CO2 + H2O + RuBP ⇔ 2 3-phosphoglycerate Higher temperature favors the reaction going to the left, with more entropy. Higher CO2 concentration favors the reaction going to the right, as per ... | [
"I think availability of water will determine which factor is dominant. C3 plants quickly become co2 limited, even under elevated co2 levels, if they are also water limited. With limited water, stoma close to prevent water loss through respiration and gas exchange stops, hence the co2 limitation."
] | [
"I'm not sure I see how water-limitation affects the interaction between temperature increase and CO2 concentration increase on C3 photosynthesis. Would closed stoma during water-limited periods mean that during the few periods when the stoma were open and exchanging gas, high CO2 levels would be vital and have a b... | [
"Increasing temperature can cause desertification in some areas whereas in others climate might become wetter. So it is really hard to predict the interplay between temperature and moisture. In either case, if the leaves get too hot, plants need to transpire to cool down. Otherwise the increased temperature can den... |
[
"Dark energy eventually overcoming gravity- would this have an effect on individual planets?"
] | [
false
] | Hello, everyone. My sister told me that you people are very nice, and I hope you will be able to answer my question on my first reddit post. My question is about dark energy. I have read articles that suggest that dark energy is a poorly understood substance that causes the expansion of the universe, and one in NewScie... | [
"The expansion due to a cosmological constant is so slow that things on shorter length scales basically \"spring back\" to an equilibrium that they want to have. This is the case for all ",
" structures, which is basically galaxy clusters and anything smaller. So the Earth is not going to get separated from the S... | [
"Dark energy has already overcome gravity, that's why the universe's expansion is ",
".",
"Don't confuse yourself by thinking that dark energy is some sort of un-gravity that kills off gravity; it's not. Dark energy is the \"something\" (force, energy, substance, we don't know) that is causing the acceleration ... | [
"It can, but it won't necessarily. It would need to have an equation of state w<-1, where the density of dark energy is w times its pressure. This is called ",
"phantom energy",
", because the guy who wrote the original article on it put it out around the time Phantom Menace came out.",
"A vanilla cosmologica... |
[
"Even though the day is longer, why is the sun rising later now than it did a few weeks ago on the winter solstice? Why do we not gain sunlight equally on both ends of the day?"
] | [
false
] | null | [
"Due to the eccentricity of Earth's orbit (deviation from a perfect circle), true noon (when the Sun crosses the midpoint of the sky) can occur several minutes before or after clock noon. This can be plotted on ",
"an analemma",
", a figure which plots the time difference between true noon vs. clock noon and th... | [
"The two main factors are ",
" and ",
". These factors lead to a discrepancy between the \"measured time\" and the \"solar time\". You may also have noticed that the sun isn't always at it's highest point at mid-day.",
"This discrepancy doesn't normally affect our day to day lives, but we can calculate it for... | [
"Others have already given good answers. But there is ",
"this interactive demonstration",
" about the motion of the Sun throughout the year which might make it a bit easier to visualise. You can change almost everything by dragging, the latitude of the observer (drag the line on the map), the time of year (dra... |
[
"What would the weak force look like if the Higgs didn't exist?"
] | [
false
] | If the W and Z bosons were massless, the weak force would have infinite range like electromagnetism and therefore (I think?) it would show up in the macro/classical world. What kind of phenomena would we observe? As far as I know there are no weak force bound states - would that change? Would it allow apparently reacti... | [
"Interesting question and I don't know the answers, but some similar questions have been addressed in the literature, see ",
"here",
" for something quite similar in spirit to your question (see the section \"the \\mu",
" > 0 universes\") and ",
"here",
" for the related question of what if there was no w... | [
"Really interesting question. I can just add some thoughts to squarlowx excellent answer. The electroweak symmetrygroup is SU(2)xU(1) before the Higgs breaks it down to U(1) at low energies, making the W,Z massive. The SU(2) being unbroken would cause confinement of the weakly charged particles, i.e. of all the par... | [
"You can manually put mass terms in the Lagrangian if you want, the problem you run into then is in spoiling the invariance of the Lagrangian under local transformations. This is gauge invariance and is one of the biggest driving factors in bringing in the Higgs mechanism. The Higgs allows you to bring in the other... |
[
"Why isn't the sun made up of large amounts of rock and metals, as well as gas? As in during it's formation I would assume it was pulling together anything or is this false logic on my part?"
] | [
false
] | null | [
"All the rocks and metals have been stripped to their constituent atoms and vaporized due to the heat of the sun. There is still, for instance, elemental iron, silicon, etc in the Sun, but it's all floating around as a plasma at ridiculously high temperatures. "
] | [
"A simple answer is that there is a bit of metal in the sun, and other elements as well. We can see the [spectral lines]() that these superheated materials give off, so we can measure them pretty well- turns out the sun is made up of about [.14% Fe and .1% Si](). So there is a whole lot more hydrogen and helium tha... | [
"Thanks for that. Appreciate the insight. "
] |
[
"Would a windmill with two sets of blades harness twice the amount of power?"
] | [
false
] | Is it even possible to have a second set of blades on the other side? Obviously it would need to be built to withstand this extra load, but would it harness twice the amount of power? It seems more cost-effective than building two. | [
"I think it is important to remember that wind turbines create energy by slowing down the wind. The faster the wind the more energy. Thus it makes sense to minimize interference between turbines so that each one gets the greatest speed. Placing two turbines directly behind one another basically maximizes the interf... | [
"The aerodynamic losses would make it much less efficient than the first pair of blades; it would certainly not output twice as much power. It would not be as economical as just setting up a second windmill, or it would already be happening."
] | [
"If you look up counter-rotating props on aircraft you will find that the designers usually figure on an additional loss of 20 to 30 % with that rig. The only reason its done on aircraft is ground clearance for the propellor tips when taxiing."
] |
[
"Are there any planets with more than one material that has a cycle like our water cycle?"
] | [
false
] | [deleted] | [
"Titan likely has liquid ethane and propane in the lakes as well, which will form as methane is irradiated in the upper atmosphere. Scientists expect to find sort of a ",
"mixed hydrocarbon sludge",
", with the heavier stuff being solid and on the bottom."
] | [
"Well it isn't liquid, but the Martian winter can precipitate both ice and dry ice."
] | [
"Saturn's moon Titan has rain, rivers and streams of what is likely to be liquid methane, so Titan has a methane cycle which is analogous to Earth's water cycle. Venus has a cloud layer that rains sulfuric acid which evaporates as it falls deeper into the atmosphere and does not reach the ground."
] |
[
"What is the evolution behind different eye colors?"
] | [
false
] | Why colors at all and how did brown gain allelic dominance over other colors? I know the colors all have their own spectrum of light to dark, but are there any rare inherited eye colors besides the common brown, gray, green, blue, and yellow (Not talking about discoloration due to disease or pink eyes in albino individ... | [
"Eye color is so complex in terms of genetics, that I couldn't really answer why some alleles are more common than others. What we do know is that brown is not dominant to blue, but that there are a huge number of loci contributing to eye color.",
"The rest though, I'd be happy to explain:",
"Colors such as ora... | [
"This is along the lines of your query and should answer it:\n",
"http://www.reddit.com/r/AskReddit/comments/l9ikm/what_is_the_purpose_of_eye_color/"
] | [
"Sexual selection is probably the only factor. Other colors didn't evolve because a random mutation that produces a functional pigment would be extraordinarily rare, all of the colors we have are all due to differing melanin concentration, not separate pigments."
] |
[
"How is it that sleep depravation can actually kill you? What is the human reaction that leads to death?"
] | [
false
] | null | [
"No one knows for certain. In a study involving rats, all of the sleep-deprived rats died in about a month. The specific cause of death in each case was unknown. Various suggestions were posited, but nothing was agreed upon. There was evidence of brain damage in some, but not all. ",
"So, in short, the speci... | [
"I feel like its only ethical to study on rats if those study's prove to save future humans (and or rats?)"
] | [
"There's a disease known as Fatal Familial Insomnia (FFI), it's hereditary, everyone of the family will be affected by it at a certain age (usually middle age). After this disease triggered people cannot sleep even for a night and they usually die within two years at the most. ",
"There's a lot that will go on wh... |
[
"What does the Higgs Boson image mean?"
] | [
false
] | I got a t-shirt of a higgs boson ( image) and i don't know what it means. I watched videos explaining the higgs field, so i know what a higgs boson is, but do not know how the image relates to it. | [
"I dug through the CERN archive for you and found the image:",
"http://cds.cern.ch/record/39444?ln=en",
"The image is from a simulation. In the simulation two high energy protons are collided. In this collision you get a mess of stuff going on with various particles produced, one potentially being the Higgs bos... | [
"The site says the muons are \"not absorbed\", rather than \"not detected\". ",
"Muons have a relatively long mean lifetime (2.2 microseconds), so they typically survive long past the end of the detector intact (the mean travel distance before decay is at least roughly c*2.2 microseconds = 660 meters, whereas the... | [
"As ",
"u/Lewri",
" found, this is a simulation of a Higgs boson decaying into four muons in the CMS detector at CERN.",
"To read this image, you have to understand a bit about how CMS works. CMS's subsystems can be divided into two classes:",
"1) ",
", which try to trace the path of a charged particle th... |
[
"Why are sulphites dangerous for some people?"
] | [
false
] | I kept reading on wine labels at work, "Contains Sulphites", after some quick research learned that it's been labeled for a while, and some people have an adverse reaction, which appears similar to an allergy - however is not an allergy. I kept looking (with Google as pretty much my only resource), but I'm not sure wh... | [
"There are a variety of different reactions to sulphite additives and the occur by a variety of different mechanisms. I think that all the different mechanisms have not been elucidated.",
"Sulphur dioxide (SO2) that can be generated from sulphite additives .SO2 is an air pollutant. It irritates the airways and ca... | [
"Wow, that was everything I had been wondering, and more. Thank you so much for your help!"
] | [
"Re: suplphites, Just bear in mind that this stuff is still being researched and it's not all clear what is important and what is not so important. There may be more recent knowledge if you can find someone who is actually working in this area."
] |
[
"How does this work? Mercury vortex bassed on Faraday's Mercury Motor. For anyone who loves physics and/or engineering. https://youtu.be/bSIzyk5Mjko"
] | [
false
] | null | [
"We don't comment on particular projects, videos, blogs, etc. on this sub"
] | [
"Then tell me where I can find a sub that does. Please don't refer me to ",
"r/findareddit",
" , as they continually have refered me to the wrong subs. Thanks."
] | [
"Maybe try ",
"/r/asksciencediscussion"
] |
[
"What is the life expectancy of a modern high rise building?"
] | [
false
] | For a modern or not so modern skyscraper (i.e. Empire State), what is the forecasted due date? I mean, I guess they build and design them with some kind of expected life time. Or are these buildings able to stand up forever as long as they are properly maintained? I am talking about the structural integrity mainly, not... | [
"Pretty much forever if you are willing to throw enough money at it. Most structures become obsolete and its cheaper to re build then renovate to the new space requirements. At some point the maintenance costs would necessitate any given structure to be demolished unless it had historical significance.",
"50 year... | [
"That is honestly a very tricky question to answer. Simply put, for the largest of buildings, we haven't yet had to consider how to tear them down. Traditionally speaking, implosion-based demolitions of skyscrapers are pretty much forbidden in cities, so the only other option is a manual deconstruction. For large s... | [
"TL;DR On average, most modern high rise buildings are designed to last >40-50 years. In practice though, they usually just get torn down for newer, bigger, and better. Vegas hotels are a perfect example.",
"One major factor contributing to the life expectancy of new construction, would be which country it's in. ... |
[
"If salt breaks up into component ions when it dissolves in water, why does it still taste salty?"
] | [
false
] | Why doesn't it taste sodiomy, with a hint of bleachy aftertaste? | [
"Even salt crystals dissociate on your tongue before you can taste them. I challenge you to taste an entire NaCl molecule."
] | [
"What you recognize as salty is the taste of sodium and chloride. Try some KCl lite salt sometime and you will notice it has a different flavor."
] | [
"There's a sodium receptor that makes up the bulk of your response to salt. IIRC, there's some evidence that chloride receptors might exist too (not all receptors are known). ",
"For instance: Ammonium chloride has a somewhat saline taste, even though ammonium ions usually trigger a bitter response. "
] |
[
"Do dyslexics have issues with all symbols, or just letters?"
] | [
false
] | If a person with dyslexia saw a Chevy logo or the batman symbol, is there a chance that it would be flipped around? | [
"Currently studying an MSc in neuroscience. Whilst language acquisition or dyslexia aren't my field of work, for my undergrad it was my dissertation supervisor's focus and my younger brother has dyslexia, so I did a fair amount of reading around the subject at the time.",
"This characterisation of it being a mere... | [
"It's a common misconception that to a dyslexic the letters appear in a different order. This isn't true. The eyes process visual stimuli correctly and the brain processes that stimuli just fine. The miscommunication happens between the section of the brain that perceives an image and the part of the brain that ... | [
"Thank you. This is very interesting and may be helpful to me (I'm an English teacher)."
] |
[
"What is the difference between mutations, variants and strains?"
] | [
false
] | null | [
"A mutation is a genetic difference between one virus (or organism) and its ancestor. If the DNA (or RNA) gains or loses or changes a base pair, that's a mutation. ",
"A variant, when talking about viruses, is a group of closely related viruses (all descended from a specific ancestor) which share mostly the sam... | [
"I apologize if I say anything wrong in advance, please correct me my Biology is a bit rusty",
"When microbes reproduce, the DNA copying stage isn't 100% perfect, and discrepancies in the \"blueprint\" are the cause of mutations, some beneficial, some lethal. These mutations, if they are beneficial and survive, g... | [
"Wouldn't mutations ",
" for strains and variants?"
] |
[
"How does the earth magmatic field shield us from gamma radiation but not from visible light?"
] | [
false
] | Edit: magnetic | [
"The Earth's magnetic field does not shield us from gamma rays.",
"It can only divert charged particles towards the poles (those form auroras).",
"Cosmic rays refers to high energy massive (having mass) particles, not gamma rays."
] | [
"Most gamma rays don't hit the surface since they interact with (are absorbed by) atoms in the atmosphere, which is many kilometers thick."
] | [
"A few things here",
"The earth's magnetic field does not shield us from light. Since photons do not carry any charge, they are unaffected by magnetic fields. The earth's magnetic field in fact protects against charged particles like protons and electrons in a plasma that are ejected from the sun. These particles... |
[
"Why are European languages's words for \"dog\" all different but their words for \"cat\" all basically the same?"
] | [
false
] | English German Spanish French Russian Greek Irish vs English German , Spanish French Russian Greek Irish The words for "dog" all sound completely different from each other, but the words for "cat" all sound the same, just adapted slightly to fit the sound of the language, like a loanword. Why is this, considering cats ... | [
"Part of this is time depth - most European languages are related (the Uralic languages, including Finnish and Hungarian, and Basque are the main ",
" that aren't on the periphery). The word for dog in many of those is related: English hound, German Hund, Latin canis, French chien, Armenian šun, Latvian suns, Rus... | [
"This is the right answer. The longer something has been around, the more different words for it tend to be. That's why words like ",
" or ",
" are very similar in all European languages."
] | [
"Dogs were domesticated in Europe at least as far back as 20-25 thousand years ago",
"Cats were introduced to europeans around 1200 BC",
"For most \"older\" european languages you could look at it as Dogs had to be named, Cats brought their names with them."
] |
[
"What would happen if a spacecraft was over the kármán line but there’s a person attached with as long as u need rope to be in the earth’s atmosphere? Would the person hang or would it bring the whole thing down?"
] | [
false
] | null | [
"The atmosphere doesn’t suddenly stop at the Von Karman line."
] | [
"Well if the spacecraft was further away in the space where there’s no gravity."
] | [
"further away in the space where there’s no gravity.",
"That's not how it works."
] |
[
"Are there any experimental evidences regarding harmful effects from medical imaging radiation doses?"
] | [
false
] | I know that in the end estimating cancer risk from radiations is almost impossible and that the LNT model is just there to have a basis for radiation protection purposes, not to give actual risks. It's pretty clear it would be almost impossible to measure these data, given the smallness of the effect and the long time ... | [
"I think this is the review you might be looking for.",
" ",
"The population that is going to get the most medical imaging are cancer patients, and there's an increasing amount of cancer patients who are living long lives with regular CT scans. It's difficult to pin second primaries on such imaging, as there's... | [
"Interesting paper, it's not what I had read. ",
"However they state pretty clearly that no direct observation has even been performed (due to the obvious extreme complexity of doing it)"
] | [
"It costs 1-2 million per CT machine, so if the rest of the world could afford it like the USA does, you would see the usage increase.",
"This sentence is wrong. Let's start from the numbers, which either are wrong or they're screwing you badly. I'm in a G7 country and the flagship best newest CT model with all t... |
[
"How does astronomical research pay dividends back to society?"
] | [
false
] | [This may not be the right subreddit to post this, please direct me to a better one if that is the case] First of all, I want to state that I am a full supporter of science research, and am enrolled to begin a chem PhD in a month. I do not doubt how exciting astronomy research is. I consistently go out and look at th... | [
"There are a bunch of reasons, but on your last points: it's basic research, not applied research. That's how basic research works, to perform research that doesn't necessarily appear to relate to anything but then will impact society in lots of ways. Astronomy tends to push a lot of technological and computing dev... | [
"Like other redditors have already said, there's a fundamental difference between basic/fundamental and applied research.",
"If you want some concrete examples of dividends paid back though. Look at your phone next time you use it to for directions or to track your incoming uber eats/doordash delivery.",
"Becau... | [
"Modern astronomy and cosmology are intimately tied with the boundaries of theoretical and particle physics. ",
"By understanding the changes and processes in other parts of the universe, we gain understanding of what the universe is made of and how it functions. This helps to either prove, shape, or eliminate ce... |
[
"Why was Japan able to quickly rebuild Hiroshima & Nagasaki while the Sendai region will be contaminated for decades?"
] | [
false
] | [deleted] | [
"Check out ",
"this thread",
". The TL;DR is that the amount of waste is proportional to the energy released. Over its lifetime, a nuclear reactor produces far more energy than a nuclear bomb."
] | [
"Thanks for the link"
] | [
"Does Hiroshima have higher background radiation than other places? Are there any recent studies on this?"
] |
[
"Why are there so many species within the same niche?"
] | [
false
] | I know evolution favors the fittest in respect to the environment. But why isn't there a single species of grass, for example? Or a single kind of fish? Shouldn't the best survivor outlive all the other kinds? Are we still in the transition phase? Are the species going extinct a step to that end? | [
"Because there are many, many more \"niches\" than just 'things that eat grass' and 'things that live in the ocean'. In fact, the total number of niches ",
" with species diversity - meaning that there are a fantastic number of niches, and essentially an infinite number of potential niches."
] | [
"niche diversification is particularly prevalent in static environments, such as rainforests. Because conditions don't change in a rain forest environment there is greater opportunity for organisms to occupy more and more specific niches."
] | [
"Yes, they are all separately filling a niche (or multiple niches).",
"Here are just a few ways in which monkeys differ:\nDiets, home ranges, living spaces (trees, shrubs, plains), predators and predator evasion, sexually selected traits, social dynamics, intelligence (energy use), behaviors... and so on. There i... |
[
"Why are a majority of people right-handed?"
] | [
false
] | null | [
"Wasn't the whole creative vs brainy being on different sides of the brain thing debunked long ago? From wiki: \"experimental evidence provides little support for correlating the structural differences between the sides with functional differences.\" Not exactly a scholarly reference, but that statement does have... | [
"There is some evidence in neurology to suggest that part of the reason for handedness has to do with the fact the left hemisphere of the brain contains much more of the memory of how we do things. This comes from looking at people who have brain injuries after stroke or trauma and develop a syndrome collectively k... | [
"There is a correlation between creativity and left handedness but I don't think it has anything to do with the left-right hemispheres of the brain.",
"Wikipedia:",
"Other reported associations include with higher creativity, a larger corpus callosum, certain right brain regions being larger, shorter transfer t... |
[
"Why are viruses not considered to be alive? If we found a virus on another planet, would be classify it as a life form?"
] | [
false
] | null | [
"The central dogma of biology is translating genetic information into proteins. However, viruses are unable to do this process on their own, which is why they infect and spread in bacteria, plants, and animals; they are using the hosts protein manufacturing facilities to aid in their own reproduction, thus they do ... | [
"https://en.wikipedia.org/wiki/Life#Biology",
"Viruses don't have a metabolism, and they don't really have self reproduction. They implant proteins in the host cells and the host cell reproduces the viruses, as opposed to reproducing themselves from their own 'body'."
] | [
"It could be argued that viruses are just self-perpetuating chemical packets I suppose, but really saying if they are a form of life or not comes down to definition only. They are shaped by selection pressures like any other form of life we know of. They simply occupy a niche where simplicity (in structure and meta... |
[
"What is the distribution of numbers picked at random by people?"
] | [
false
] | This is sort of a thought experiment, but I also want to try it out eventually. I thought I'd ask beforehand to see if science is able to predict the results: I want each person in a large group of, let's say, 50 people to choose a number from 1 to 4. Each person picks his/her number silently, so that no one else knows... | [
"Introducing possibly the least scientific science experiment ever:",
"AskScience numbers poll"
] | [
"Eesh, after reading comments that say I probably won't pick 1 or 4 and that 60% of kids in a class picked 3, I found that difficult. ",
"This is why I used the random number function on my calculator to make guesses in multiple choice exams."
] | [
"I don't know of any way to truly predict the distribution, but there are general rules for the way people choose 'random' numbers. Namely, people associate \"random\" with \"no patterns\". If you're talking about a large pool of people choosing 4-digit numbers, you're likely to get a disproportionately small amo... |
[
"[Chemistry] What determines if a reaction is endothermic or exothermic?"
] | [
false
] | In our thermodynamics unit in chemistry, we learned all about chemical reactions and changes in entropy and enthalpy, but we never discussed what actually determines if a reaction releases or absorbs heat energy? | [
"The simplest rule that gives a guideline is bond formation and breaking. As a bond forms this lowers a molecule's energy, releasing energy(exothermic) conversely breaking a bond increases the energy of the components, absorbing energy(endothermic). Bonds of different elements, multiple bonds all play major factors... | [
"I wanted to respond to this question a bit because I think you're actually asking some pretty good questions here. ",
"As a general rule, a reaction can proceed when the reactants have enough energy to overcome the activation energy for a reaction. You have the right idea that in a bulk sample, there are some m... | [
"And the reactants in endothermic reactions need to be energetic enough (temperature) to have the potential energy to form those bonds? If so, in what way is the molecule energetic? Are the electrons at higher energy levels (i.e. working their way up 1s, 2s, 2p, ...). Also if so, are reactions incomplete because te... |
[
"How valid is the concern over arsenic in pressure-treated lumber?"
] | [
false
] | A playground from my childhood was torn down a few years ago, not because it was worn out, but because it was built with pressure-treated lumber and a local parents' group became concerned about arsenic exposure. How valid are these concerns? I've done a bit of Google research and read some information pages like , as ... | [
"It looks like it's a source of exposure, but the amount can vary greatly depending on the conditions. The amounts mentioned in the study seem fairly low and in line with other environmental arsenic exposures (e.g. drinking water). That said it looks like it would still be a source of exposure for kids on a playgro... | [
"I looked at a Canadian proposal for doing some research on treated pallets where the risk was not arsenic, but cobalt. "
] | [
"Not very valid imho. Most places re-seal the wood periodically, so kids aren't even exposed to the underlying wood. Even then, unless they are eating it, I don't see how the exposure could be high enough to cause a problem. "
] |
[
"What is the biological cause/purpose of a sneeze?"
] | [
false
] | [deleted] | [
"It's triggered by a small object entering your nose, such as a speck of dust. It's supposed to prevent irritants and infectious agents from getting to your sensitive lungs."
] | [
"why then do some people sneeze when they go out into the sun?"
] | [
"There are controversies regarding the mechanisms. Apparently it is caused by higher sensitivity to visual stimuli in the visual cortex and of co-activation of somatosensory areas (",
"here",
").",
"It is called the ",
"photic sneeze reflex",
" or ",
"ACHOO syndrome",
" :)."
] |
[
"When bending a metal rod at a joint repeatedly, heat is produced.... Why?"
] | [
false
] | When someone bends a metal rod at a specified point over and over again (back and forth), the metal heats up at that joint. I am assuming this is because of friction? If it is, then I suppose my question is how does friction create heat in this scenario. | [
"This really needs to be on the side panel somewhere, along with, \"No, you can't go the speed of light\". You have to ",
" energy to break chemical bonds, not the other way around.",
"Energy is released when chemical bonds form, and you will observe a net increase in temperature if the bonds you make are more... | [
"your entire answer should probably be reposted so I can vote it to the top outright."
] | [
"When you are doing this, you are plastically deforming the material. This is breaking bonds within the material which releases energy. Most of this energy is released as heat."
] |
[
"What were the main death causes for early Homo sapiens sapiens?(around 50k years ago)"
] | [
false
] | [deleted] | [
"I'd like to point out that this is difficult to answer because cause of death is often linked to fossilization. That is, a person who lived to old age and was buried under a pile of rocks is far more likely to leave remains that persist to the modern day than someone who is killed by an animal on a hunting trip."... | [
"True. However it's well documented that the two leading causes of death in antiquity (i.e., far enough in the past to predate modern medicine but not so far in the past that we don't have records) were (1) childbirth and (2) childhood infectious diseases. It seems reasonable to assume these were persistent problem... | [
"Well with small populations and few to no domesticated animals, childhood infectious disease was probably less common than it was in later periods of history. Also, death in adulthood is probably a more interesting topic."
] |
[
"Why do bones become abnormally long in Rickets?"
] | [
false
] | [deleted] | [
"Looking here (Page 872)",
"Here's an image from the article, because I couldn't figure out how to copy/paste.",
"I'm thinking he might have been tricking you, everything I'm reading suggests the opposite."
] | [
"The osteoblasts keep laying down osteoid which does not get mineralized."
] | [
"Where did you read that bones become abnormally long? I'm just generally curious, looks like an interesting thing to read about."
] |
[
"Scientifically, can anyone explain what mercury does to argon gas to cause it to glow brighter?"
] | [
false
] | It was on how it's made. Mainly i'm wondering if the mercury turns into a gas, or if simply the Hg interacts with the argon somehow? | [
"adding mercury to fluorescent lights? mercury emits a strong ultraviolet line at 254 nm quite efficiently, where argon can absorb this light and convert it to a broader spectrum that is more effective at uniformly exciting the phosphors on the inside of the glass. It's also better to use heavier atoms with hot... | [
"Mercury also emits a pretty bright green line, smack down the middle of the visible spectrum. In fact, I think mercury lights produce all colors easily except red, unless you do something about it."
] | [
"Please explain..."
] |
[
"What are metal air batteries?"
] | [
false
] | Not much on the wikipedia page for metal air batteries. Whats the diffrence to lithium ion are they more expensive, hows thier weight to energy ratio... | [
"Also: What is the Energy to Volume ratio?"
] | [
"facepalm...",
"I meant: What is the energy to volume ratio ",
"?"
] | [
"The Wiki pages for the specific battery types have quite a bit more info than the general overview page, which may help answer your questions.",
"https://en.wikipedia.org/wiki/Metal%E2%80%93air_electrochemical_cell",
"https://en.wikipedia.org/wiki/Zinc%E2%80%93air_battery",
"https://en.wikipedia.org/wiki/Alu... |
[
"When I get a cold, how much of the symptoms/misery are caused by the illness itself and how much are caused by my body's reactions to the illness?"
] | [
false
] | null | [
"Actually, some pathogens ",
" create illness symptoms directly-- e.g. you can get food poisoning from eating the botilinum toxin produced by the bacterium... no bacteria nor immune response fighting the bacteria is necessary. Furthermore, when a virus replicates, it tends to kill the host cells, and in a cold t... | [
"Calling every chemical reaction that happens in the body 'your body's reaction' is a little misleading."
] | [
"Calling every chemical reaction that happens in the body 'your body's reaction' is a little misleading."
] |
[
"We have gravity because the mass we are sitting on is accelerating. We are attracted to larger objects because their accelerating mass causes a space to curve. Why do scientists make the statement that we have acceleration because we have gravity and not the other way around?"
] | [
false
] | null | [
"Because the premise:",
"We have gravity because the mass we are sitting on is accelerating.",
"is incorrect. Mass and energy curves space. Acceleration is not a prerequisite."
] | [
"@rupert1920 - At the risk of making an error in etiquette (this may fall under the category of \"layman speculation') if there was no acceleration, would not the curves in space be less pronounced? Alternatively, if all masses in space stopped accelerating, would we, as Einstein speculated: Not feel our own weight... | [
"I think I'm beginning to understand what you mean now.",
"An object only under the influence of gravity undergoes no acceleration. That's because the curvature of space is bending the inertial path of objects through spacetime. So an object in freefall is in an inertial reference frame, and objects within it wil... |
[
"Why is my breath warmer and more humid when I \"haaa\" (to clean my glasses) than when I blow air through pursed lips (i.e. blowing out candles)?"
] | [
false
] | Don't know how else to describe the difference. Anyone understand what I'm talking about? | [
"Other than the speed of the air mentioned in the other comment, the actual air flowing past your hand is also cooler and drier. ",
"A fast moving stream of air causes a phenomenon called entrainment, where surrounding air gets pulled into the jet you're blowing. "
] | [
"Velocity, similar to how wind feels colder (wind chill) when it is moving faster. The rate of heat loss from the area you are blowing on depends on a) the temperature of the air, and b) the speed at the surface of heat loss. Since the former is relatively constant given it originates from an area at body temperatu... | [
"I believe it is because the air is more humid if released like that. Our nose saves us a lot of water by making the air swirl around on its way out giving it better conditions to condense. On cold days the nose litterally drips of condensation. If yawning the air would be coming directly from the lungs which is 10... |
[
"I understand that our body is constantly replacing cells but, is there any part of my body which I would be able to touch, which would be the same cells from birth?"
] | [
false
] | Ok, kinda weird but...I saw a photo of myself the other day at the age of around 3 (I'm 21) and I had a thought that; although it's me, every single cell would have been replaced by now. So I assumed that there is nothing in that photo which would be the same cells I have today and I could touch? Then I wondered about ... | [
"Plus I guess it depends on how you define \"can touch\" :)"
] | [
"Plus I guess it depends on how you define \"can touch\" :)"
] | [
"If you really wanted to, you could touch your own brain, but it would be quite an ordeal."
] |
[
"Does the horsepower rating of an engine mean how much kinetic energy it can produce in a certain amount of time?"
] | [
false
] | null | [
"Yes. Technically, it's ",
"angular kinetic energy",
" but it's basically the same.",
"Keep in mind that the horsepower rating of an engine is its ",
" power.\nThat is, at full throttle and exactly that many rpm, the engine produces this much ((angular) kinetic) energy per unit of time. In all other circums... | [
"An engine can also produce other kinds of energy, so the answer is no. Horsepower just gives you the power of an engine, the energy it can produce in a certain amount of time, but as I said before, no specific type of energy.",
"Source : ",
"http://en.wikipedia.org/wiki/Horsepower"
] | [
"While this is true, in general things that are measured in horsepower are rotational engines. The rest of the world measures the power of their car's engines in Watts (kilowatts, actually) while Americans are still using the English system of horsepower. So when you measure the power output of an engine you are ... |
[
"What happens to the body when your cortisol levels are constantly too high?"
] | [
false
] | null | [
"The short answer is this condition exists in a genetic form known as ",
"Cushing's Disease.",
" This leads to a well established pathology of ",
"insulin resistance",
" and all the complications that comes along with excess insulin exposure to include:",
"Weight Gain",
"High Blood Pressure",
"Memory... | [
"This is a really broad question, since excessive cortisol in the human body can have a lot of implications. I'll just talk about one of them.",
"One area of your brain that has a lot of cortisol receptors is the hippocampus. There is some evidence that excess cortisol can cause the hippocampus to be damaged in v... | [
"How would one know if they had high levels of cortisol? Without going to a lab... Etc.."
] |
[
"Is the concept of DNA universal? would alien life be based on DNA?"
] | [
false
] | null | [
"That's what ",
"/r/AskScienceDiscussion",
" is for though. Here is for answering questions people may have. "
] | [
"As always, the details regarding \"sameness\" are important here. For example, the animo acids and ribose sugars used by life are ",
"asymmetric",
", meaning that half of the possible arrangements are not used. There is no strong evidence that this use of L-animo acids and D-sugars is ",
" for life, so it wo... | [
"This may be a reference to the old idea that in an eternal universe life need not have ever had a beginning, and would simply have spread via panspermia from planet to planet eternally. But an eternal universe is not at all well supported by the evidence."
] |
[
"What enables aquatic mammals to hold their breaths for so long?"
] | [
false
] | Wouldn't the animals be using oxygen for swimming, as their muscles would need it? Why can't humans hold their breath for so long? | [
"The primary reason is the mammalian diving reflex. When a mammal submerges its face in cold water, a couple of different reflexes kick in. First is bradycardia, which immediately drops heart rate by 10-25% (or more in some animals), conserving oxygen. Next is peripheral vasoconstriction, where capillaries in the b... | [
"Most deep diving marine mammals aren't actually holding their breath on a dive. Deep diving whales will actually exhale before a dive.",
"At first that seems counter-intuitive and doesn't make sense, but marine mammals(save for those like otters and polar bears) don't actually store the majority of their oxygen ... | [
"They can function for a while at that rate, but not indefinitely. The heart rate has to return to normal to restore oxygen to the body after it has been depleted during the dive."
] |
[
"Why can't our eyes instantly adjust to changing light levels?"
] | [
false
] | When I walk from a dark room to a light room (or vice-versa), why can't my eyes instantly see clearly? Does it have something to do with the rods and cones in our eyes? Can the muscles controlling the dilation of my pupils not move fast enough? | [
"In essence, this is due to cones obtaining more sensitivity when first entering the dark for the first five minutes but the rods take over after five or more minutes.",
"Also this - ",
"The ",
"Purkinje effect",
" is the tendency for the peak luminance sensitivity of the human eye to shift toward the blue ... | [
"If it takes you 45 mins to adjust ... you got issues."
] | [
"It has to do with rods and cones. \nRods are more sensitive to light and are unable to convey information under bright lighting due to over saturation. Cones are less sensitive and are able to meaningfully signal information in bright settings but are not sensitive enough under dimmer lighting. When you go from li... |
[
"How is GPS so accurate? How is it able to tell me where I am within a few meters when the satellites are thousands of miles in space? How do they correct for minor drifts due to gravitational inconsistencies?"
] | [
false
] | null | [
"GPS satellites work essentially by triangulating your position from several satellites in orbit. As a first approximation, one satellite can give you your position on a sphere around the satellite. Two can give you your position on the circle that defines the intersection of the two spheres around the two satellit... | [
"A small correction, the idea that GPS satellites use triangulation to determine your position is a common misconception. ",
"These satellites use trilateration instead, which determines position based on the object's distance from the various satellites. "
] | [
"Fun fact. GPS satellites also correct for the time dilation effects from special and general relativity. These are of course very small changes in how GPS satellites perceive time when compared to an observer on Earth, but it makes a noticeable difference considering how important an accurate time measurement is f... |
[
"If a Gas Giant with a rocky core migrated inwards toward a star and had its gasses \"blown off\" by solar wind over time, what would its exposed core look like?"
] | [
false
] | I was reading about Gas Giants today on Wikipedia and the exotic forms of Hydrogen that exists in them and was curious about this. If I have my physics correct, a so-called "Hot Jupiter" that migrated close enough to its star would have its hydrogen slowly stripped off by the solar wind. That would cause it to shrink i... | [
"This is askscience, harder questions have been answered."
] | [
"This is askscience, harder questions have been answered."
] | [
"Aside from metallic hydrogen, isn't there also metals like iron in the core of gas giants? As the metallic hydrogen converted into its gaseous state an was blown off, wouldn't the other metals be left behind? "
] |
[
"Why are the Planck Units calculated using G, h and c, why are these called \"fundamental\" constants and why do they show up the limits of applicability of our physical theories?"
] | [
false
] | null | [
"I'd be very cautious in ascribing any physical significance to Planck units at all: they really have none that are known. I mean, the Planck mass, for instance, is about 22 micrograms: ",
" Nothing of any cosmic importance there."
] | [
"There's a redundant set of fundamental constants. Some can be defined in terms of other ones or vice versa, but nobody really knows which ones are 'more fundamental'. ",
"Planck units one of a number of sets of ",
"natural units",
". You change the units of your problem so the constants equal 1 and it simpli... | [
"Yes, but the fine structure constant is a simple arithmetic combination of ",
", ",
", and ",
". It's somewhat arbitrary which constants you consider to be the most fundamental, and some scientists do take the fine structure constant to be more fundamental than, say, ",
". But the number of elements of the... |
[
"The universe today is made of baryonic matter, dark matter and dark energy. How did they estimate the percentage of the universe that is made of dark energy?"
] | [
false
] | I've seen this diagram before in various articles or videos: I understand the way to estimate visible matter (starts, planets and other bodies). I understand the "missing mass" problem and how they estimate the dark matter. But how did they reach the ~70% estimation of dark energy? Why is it even there with other matte... | [
"But how did they reach the ~70% estimation of dark energy?",
"Our universe is, observationally, best described by general relativity using the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric.",
"In the FLRW metric, there is a ",
"density parameter",
" representing the average energy density of the univer... | [
"They measure the acceleration of the expansion of the universe. If this acceleration comes from a type of energy with a negative pressure then that's the amount of energy you need to fit observations. You can find different models where dark energy is not an energy density, but this is the most popular way to desc... | [
"Thanks for the reply!",
"\nThis explain quite simply the phenomenon :)"
] |
[
"What does weight and bias in an artificial neural network corresponds to in a brain, and how does it work?"
] | [
false
] | null | [
"Neurons in a brain interact through synapses. Almost every neuron has an \"Input\" which are dendrites and an \"Output\" which is the axon. Synapses are the connections of the axon of a neuron with the dendrites of another neuron. ",
"A signal that comes from the first neuron, is translated into an amount of che... | [
"I assume you know what an action potential is then. The signals that come from the dendrites are similar albeit the need not be sharply spiked. They can be broader and lower in intensity. A strong signal has a high intensity and is very broad, while a weak signal is the opposite. I mentioned above that the strengt... | [
"Technically, the weights are supposed to represent synaptic strength / strength of connections between neurons. However, ANNs don't really resemble the brain in any meaningful way..."
] |
[
"What would be seasons like on tilted habitable moon of gas giant?"
] | [
false
] | null | [
"Hi homemadepanda thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the f... | [
"Planetary Sci."
] | [
"'Planetary Sci.'"
] |
[
"What's happening in our brains when we're trying to remember something?"
] | [
false
] | null | [
"The process is not completely understood, but it's thought to occur through the use of engrams or neuronal traces. Essentially these are encoded chemical changes in specific neuronal network pathways that make them more likely to fire in specific sequence, corresponding to the stimuli that triggered it. This is be... | [
"Nobody knows! We don't know how memory works really, but we have a few ideas. Memory is super complex and truly amazing.",
"The hippocampus is involved in some way with memory making, and memory recall. We don't understand the mechanisms underlying this well enough though.",
"Memory is ",
" stored across the... | [
"The coolest part is how unlikely recalled memories are to be accurate. ",
"Sometimes you have a vivid memory of something that's just blatantly ",
". ",
"Yet eye witness testimony holds so much weight in our legal system when it's flawed both by our imperfect biology, and human's tendency to lie"
] |
[
"[Quantum/Gravity] If a particle has a probability distribution of location, where is the mass located for gravitational interactions?"
] | [
false
] | Imagine an atom or an electron with a wave packet representing the probability of location, from what point does the mass reside causing a gravitational force? I understand that gravity is very weak at these sizes, so this may not be measurable. I taken classes and listened to a lot of lectures, and I never heard thi... | [
"from what point does the mass reside causing a gravitational force",
"The expectation value (or average value) of that will be the same as the expectation value of where the electron is. E.g. for any electron in an atom, the expectation value for its location will normally be at the nucleus. The gravitational fo... | [
"However, even for electron-electron interactions (which are quite correlated) this \"mean field approximation\" is about 98% accurate.",
"In what context is this statement true (especially the specific number), molecular calculations?"
] | [
"The specific application I had in mind was the ",
"Hartree-Fock method",
", which is a self-consistent mean-field approach used for describing electrons in atoms and molecules but also solid-state. To be more clear, 'self-consistent' means you change the (single-electron) wavefunctions to fit the mean-field fo... |
[
"Do electrons in an atom have velocity?"
] | [
false
] | From what I've read online about this subject, it's clear that electron in its ground state doesn't really move inside an atom in a classical sense, but rather oscillates as a standing wave. However, I've also seen calculations that measure the speed of electron to be approximately 1/137 times the speed of light or 220... | [
"The electrons don't have well-defined positions or velocities, however you can calculate the expectation value of the speed (the average velocity is zero) or the RMS velocity. You can define a quantum-mechanical velocity operator with ",
" = ",
"/m, where ",
" is the typical momentum operator, and m is the m... | [
"You cannot reproduce all of quantum mechanics with classical mechanics and simple probability. This is demonstrated by ",
"Bell's theorem",
"."
] | [
"How do you define “traveling”? It doesn’t have a well-defined position or momentum. You can calculate expectation values and various moments of its position and momentum distributions. It’s “moving” in a quantum sense, which is described in a fundamentally different way than classical motion."
] |
[
"Do objects cast shadows in the rest of the electromagnetic spectrum?"
] | [
false
] | Why does visible light get blocked by objects, but for example radio waves travel through walls and the like? | [
"X Ray film is essentially capturing the x ray shadow of the various body components being photographed. "
] | [
"It depends on the composition of the object and the type of EM radiation. For example, ordinary glass in opaque to UV light and would therefore cast a shadow. The metal grating on the window of your microwave is opaque to microwaves and lead is opaque to x-rays."
] | [
"think it was supposed to be \"ordinary glass ",
" opaque to UV light\""
] |
[
"Are there places on earth where the gravitational pull is weaker?"
] | [
false
] | null | [
"Yeah, you can see them on ",
"this map",
". In the units they use, a gal is 1 cm/s/s."
] | [
"Yes, the ",
"earth is not a perfect sphere",
", therefore there are parts of the earth that are further from the centre than others.",
"This means that the parts that are further away (specifically at the equator) experience a lower gravitational constant. The further you move from the centre of the earth th... | [
"Indeed what you write is true, but not complete; see iorgfeflkd's answer with map of gravity distribution. Not only is the earth not perfectly spherical, its mass is unevenly distributed."
] |
[
"Why is Lead a good radioactive shield?"
] | [
false
] | null | [
"Lead (and other dense metals like cadmium) are good at shielding gamma radiation because they are dense. High atomic number and relatively short bond length means there are a lot of electrons for incoming photons to interact with. When the photons that make up the gamma radiation interact with the electrons and tr... | [
"For good radiation shield you want an element that has heavy nuclei to absorb the radiation. Very heavy elements tend to be unstable and hense radioactive themselves. Lead is very common, heavy and stable to be widely used."
] | [
"Lead is a heavy nucleus with very tight electron orbitals. These characteristics mean it slows down high energy electrons very quickly, which cause them to give off high energy EM radiation that includes X-rays. Less dense material will allow the beta particles to slow down more gradually (over the course of sev... |
[
"If the universe is expanding and accelerating, is time expanding too?"
] | [
false
] | I was just thinking and not sure about something. This is not in question form, it is more like my thought process written out for someone to edit and correct. Space and time are the same thing...and the universe is expanding faster and faster. So if space is expanding and stretching, time must be doing the same thin... | [
"No, just space. Distant objects in space are getting farther apart by about 70 km/s/megaparsec, and getting older by one second per second."
] | [
"The distance between two things that are separated by a megaparsec (3 million lightyears) increases at 70 km/s."
] | [
"You're trying to define the passage of time using time itself. Time can't pass faster or slower because 'faster' and 'slower' are both rates - units per ",
".",
"The point is that it doesn't matter. Whether time is \"accelerating\" as time passes makes no difference to someone living inside the universe. We... |
[
"Why would a diet based purely on drinking soylent be bad for you?"
] | [
false
] | What difference would there be between eating varied food and soylent? Since they are fundamentally made of the same things, fat, carbohydrates, protens, vitamins, and etc, how would the body recognize when you eat varied food and non-varied food? | [
"As long as the nutrients are there, there wouldn't be much difference in the short term.",
"Long term, you would start to adapt (as in physiological changes) to a liquid diet, and going back to solids would be an arduous process.",
"But it'd have to be perfection in a tube, to be effective and not mess you up.... | [
"But it'd have to be perfection in a tube, to be effective and not mess you up.",
"Also, there's so much still not know about human nutrition that sticking to a single method of food-intake could be risky, as what is currently known about 'everything we need' could be outdated by new discoveries next year."
] | [
"/u/kidrid",
" made a solid point about returning to solid foods after long-term use of soylent.",
"Taking in adequate fiber would be something to consider too. In addition, foods often contain trace amounts of minerals like fluoride, chromium, or boron, which aren't conclusively shown to be nutrients (especial... |
[
"Follow up to \"Directions in Space\" question: How does interstellar navigational terminology work?"
] | [
false
] | This is sort of a follow up question from a popular post on AskScience earlier but more specific: How does one specify/communicate a direction for interstellar travel? For example, if I want to orient someone to travel to Alpha Centauri from Earth, what navigation terminology would you use to specify the direction? Sim... | [
"since nobody did it yet, it's kind of sci-fi question.",
"but there are some ways to do it... for example, you could use reference frame from known pulsars - the same way position of earth is depicted on voyager golden plates. pulsars in our galaxy are quite well identified by frequency of rotation. if you just ... | [
"It's kind of impossible to say where something is without a system. To do so would be like trying to figure out which way is up in zero gravity (please, no Ender's Game references. What he does would be applying a system anyway).",
"As for the system itself, anything based off where it appears to be would not wo... | [
"Yeah I guess I was basically asking what is the most current system for communicating a travel path...but it seems were still a bit too far from interstellar travel to have one at the moment. Excellent point on the gravitational lensing also, I hadn't thought about that. "
] |
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