title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Difference between a Redox reaction and a Displacement reaction?"
] | [
false
] | Are displacement reactions technically redox reactions? Don’t need a particularly long answer. | [
"Redox transfers electrons between atoms, changing the valence. Usually with acid/basic products and with some dissolution on water. ",
"Displacement transfers atoms between the reactives, it's a quite big term.",
"They are different. Redox remove/add hydrogens or OH from reactives, so they might be displaceme... | [
"So redox are a type of displacement?"
] | [
"Sometimes, if the moved atoms don't form new molecules. Say HCl+Fe2O3 will only move Oxygen atoms and will change valence of both Cl and Fe. ",
"But if you have reactive 1 and reactive 2, one donates H and the other an OH, hey change valences and stay as separate elements and they create water (ending with produ... |
[
"After the big bang, did the universe cool so uniformly that it went from foggy to transparent at roughly the same instant everywhere?"
] | [
false
] | I've read that for the first 380,000 years light couldn't propagate due to charged particles absorbing and re-emitting photons. I imagine that if it were possible to be there during that time, the universe would have looked foggy or cloudy. I've also read that the CMB radiation is incredibly uniform in every direction.... | [
"The Universe wasn't entirely uniform - after all, the CMB isn't entirely uniform either, and we see non-uniformities like galaxies and people and cats today. Regions with different densities had slightly different temperatures, and so recombination happened at slightly different times in these regions. But remembe... | [
"Thank you. Do you know what the variance was in real terms? Would it have been seconds, minutes.. years? "
] | [
"It's a fairly complicated calculation and a quick look through the literature didn't yield any answers. A back of the envelope calculation, though, shows that the 10",
" factor propagates through without any significant changes (as you might intuitively expect) so the time difference would be on the order of 10"... |
[
"When a person moves their eyes from the left-most position to the right-most position, the Field of View seems to \"jump\" rather than smoothly panning. Why is this?"
] | [
false
] | null | [
"Those are two different kinds of motions your eyes are capable of making: ",
"saccades",
" and ",
"smooth pursuit",
". There is some amount of masking / blocking of processing of visual information that occurs when you make a saccade. This is called ",
"saccadic masking or suppression",
". I recommend ... | [
"In simple terms, your body's nervous system has two ways of moving the eyes. \"Saccades\" are jerky and fast movements of the eye used to locate an object. \"Smooth Pursuit\" is more of a reflex that slowly tracks an object that has already been located. When you voluntarily look left to right, you are suddenly lo... | [
"Partly it's because the movement is very quick, but also your brain \"switches off\" reception from your eyes during the movement to stop you getting disoriented. It then backfills your conscious experience so you never notice anything awry.",
"This is why, if you glance at a clock at the right moment, it can se... |
[
"Is there a maximum density?"
] | [
false
] | If density is just how close the atoms are to each other, surely there's a breaking point for the atoms, right? | [
"As you cram atoms closer and closer together they start to form what is called degenerate matter. For example if you have a big ball of hydrogen that is collapsing under its own gravity (aka a star) first it will form a dense configuration that avoids the electrons all getting smushed together, but if that gets to... | [
"The center of a dark hole or the singularity point is theorized to have Infinity density because it has no measurable volume, but as it becomes heavier it's shwazschild radius increases, but the density of the black hole from its event horizon decreases, some of the largest black holes in the universe are less den... | [
"As far as we know that is the limit. What we don't really know is how matter is organized inside a black hole (we just assume it's all condensed at a point)."
] |
[
"how does internet travel through cables as data? essentially what is it, and what effects its speeds?"
] | [
false
] | null | [
"Internet traffic through cables actually can take on many different forms, depending on where it is. Like most communications protocols, it is built up in protocol \"layers\", with the lowest layer (Layer 1) defining what physically happens in the medium to send bits (1s and 0s). Higher layers define what differe... | [
"In a coaxial cable, the signal typically travels at 2/3 the speed of light. Fiber optic cables often have a different kind of glass in the core so the light travels at similar speeds."
] | [
"Speed if affected by the type of the cable. Coaxial cables allow signals to travel at about two thirds of light speed, in fiber optics it depends on the actual material used (its refractive index) and can range from 60-something to 99% of speed of light, but cables that are used in practice are also around two-thi... |
[
"Why do super capacitors have such low voltage ratings?"
] | [
false
] | Does their low voltage ratings imply that the dielectrics within have a low breakdown voltage? | [
"Yes well the dielectrics aren't really normal ones. These are like electrochemical cells. Voltage beyond tolerance chemically alters the component. "
] | [
"Exactly, the voltage is limited by the breakdown voltage of the liquid electrolyte. For example for aqueous electrolytes this value occurs at ca. 1.2V, higher voltages resulting in water being chemically dissociated. The value that matters is the voltage at each liquid-electrode interface, so at each interface the... | [
"Hmm, I'd be careful. Sounds like a resonant cavity, or a waveguide, which would have a ",
"characteristic impedance",
"."
] |
[
"How much memory do different animals posses?"
] | [
false
] | Mostly, how much of their environment do different animals remember? How do they know how to return to their nest? How do they know where the food /water is? Do insects remember their surroundings? Bees obviously have to remember where their hive is, but what about different insects that simply move around all day with... | [
"Different animals might have different kinds of memory that are useful in their environment. For example, Clark's nutcrackers have really good spatial memory. Studies have shown that they can remember where they stored food for the winter better than graduate students, but they may not necessarily \"remember\" a... | [
"That is an urban legend. Gold fish can remeber for much longer than that. "
] | [
"Yah, one can't really answer the question because the question is too broad. Some (likely most) animals don't have memory in the same way that we have memory. For instance the ants used above is a good example. They don't need a memory (and may not even have much of one) because they can follow scent trails. I... |
[
"How effective are face masks in polluted areas?"
] | [
false
] | Seeing the pictures of the pollution in Beijing, I was wondering if anyone knew how effective masks are at filtering out the nasty bits. Do they make a difference? | [
"The constitution of those \"nasty bits\" is extremely variable by location and atmospheric condition. There are many constituents to air pollution including very large particles (i.e. dust), particulate matter (ranging form course-ultrafine), and various organic vapors. The problem is that most of the serious hea... | [
"Regarding surgeons, I think the idea is to try and separate the surgeon's mouth and nose from the patient's internal organs, at least as far as liquids like spit and snot are concerned. Human mouths are full of bacteria and a single sneeze could really be harmful if any of that saliva or mucous ended up inside th... | [
"Also regarding surgeons, those types of masks could prevent blood splatter getting in your mouth. "
] |
[
"Can seemingly clear gases be seen with electromagnetic waves not visible to the human eye?"
] | [
false
] | Saw on the front page and started thinking about all the things that can only be seen with infrared and made me wonder if it worked with Oxygen or nitrogen or some other seemingly clear gas. | [
"Depends what you mean. We can definitely use electromagnetic waves to tell if theres any invisible gas present (more energy would get absorbed than in a vacuum), not sure if that data could be presented through photogtaphy though. Now for IR and UV - also yes. Things coated in materials that only block light in th... | [
"Yes and no.",
"Gases have absorption/emission spectra that extend into the IR. Here is the ",
"spectrum for atomic hydrogen",
", and all the lines past ~700 nm or so are IR lines.",
"But these lines also extend in the visible range, and we consider the gases to be transparent because they only absorb a sma... | [
"This is wrong. For an ideal blackbody there is a universal relationship between temperature and emission. But for real objects you need to use ",
"Kirchoff's Law",
" and multiply the blackbody emission curve by the wavelength-dependent absorption coefficient for that material. In other words, if an object does... |
[
"Viruses tend to affect a very limited variety of creatures and don't often jump to different species, why is rabies different?"
] | [
false
] | I know that swine flu and avian flu mutated from their respective variants, and ebola is often found in monkeys, but how does something like rabies so readily effect large varieties of species? Swine flu makes sense, because farmers would be commonly exposed and a rare mutation would allow it to jump, but how can a rab... | [
"You have to remember that humans are just big mammals. If a virus binds to a fairly ubiquitous receptor then we more than likely can be infected. Influenza is a great example because hemagglutinin binds to sialic acid-containing molecules and those types of receptors are everywhere, so much so that influenza evolv... | [
"Most humans will encounter irreversable health risks when their temperatures drop below 95°F for extended periods of time. You would have to sustain that low temperature for so long to kill the virus that the risk of you causing irreversible damage to the patient would outweigh the benefit. It's a double-edged swo... | [
"I've had the rabies vaccine it's a wholeot of injections at the site of the bite. Then several more needles in the arse. Then come back in a few weeks for another needle in the arse and repeat 3 more times.",
"The best bit Is at the end they say this should prevent rabies, however they won't know for sure for 12... |
[
"If virtual particles aren't necessarily real, but rather mathematical artifacts created to help calculate quantum field interactions, then how likely is it that the theory of Hawking Radiation is a real phenomenon, as the theory itself relies upon the real existence of virtual particles?"
] | [
false
] | null | [
"Hawking radiation does not rely on virtual particles literally existing."
] | [
"I'm not an expert on this obviously, but as I've seen it explained, Hawking radiation works via two virtual particle pairs popping into existence near the event horizon, with one of those particles at times being sucked down into the black whole and the other left to freely \"radiate\" away from the black hole, in... | [
"That's a pop-science explanation that Hawking himself said is oversimplified. There is no physical phenomenon which relies on virtual particles literally existing. If that weren't true, then the consensus among physicists would not be that virtual particles are just mathematical artifacts."
] |
[
"Any truth behind these Muay Thai training techniques?"
] | [
false
] | [deleted] | [
"Been doing Muay Thai for a while. Regarding the Muay Thai training 'legends', there's a kernel of truth in them. In Thailand, some fighters do train by striking -banana- tree trunks. Banana tree trunks are of approximately the same hardness of a modern heavy bag. They are not going out and grinding metal, or punch... | [
"I've got almost 20 years of Martial Arts experience, including a 3rd degree black belt in Shotokan Karate, as well as a number of years experience in Muay Thai, wrestling, Jiu Jitsu, Judo and boxing.",
"While I am painfully familiar with the first type of conditioning you mention; that of repeatedly hitting a ha... | [
"This concept was featured in a discovery channel show. They had guys that would punch through concrete and ice. They found that their bones were much denser then a regular persons, but only in the impact areas. "
] |
[
"Why are Neutrinos so important?"
] | [
false
] | 1) Neutrinos are all around us 2) Neutrinos are assumed to have mass 3) Since Neutrinos have mass, they can change their "flavors" and morph into 3 types of Neutrinos 4) Neutrinos are fasttttttt 5) Neutrinos are incredibly hard to detect 6) Although they are hard to detect, there are billions amongst us : 1) If Neutrin... | [
"1) Neutrinos only interacts with the weak force, and seldomly at that. It therefore takes a massive amount of potential interactions for one to occur.",
"2) To my understanding, they are not more relevant than any other fundamental particle. It is suspected that they may be a key part of dark matter, however, wh... | [
"Point 3 is wrong. Neutrinos were first proposed in 1930, and first detected directly in the mid-1950s, as recounted ",
"here",
". They are not a fairly new discovery. Even the mu neutrino was detected by 1962.",
"The challenge is that neutrinos are neutral, nearly massless, and interact weakly, so they are... | [
"Do the three different types of neutrinos behave differently? What distinguishes the difference between each type of Neutrino?"
] |
[
"Why do most primates have five fingers?"
] | [
false
] | [deleted] | [
"A ",
"homologous trait",
" is a trait shared by a common ancestor and all its descendants and some descendants may modify this trait. The trait of five digits (pentadactyly) on the hands or feet actually dates back way before primates ever existed and it incorporates more then just the five digits, but actuall... | [
"most?"
] | [
"some of the Colobus monkeys have a lost or reduced thumb as an adaptation to tree-dwelling locomotion"
] |
[
"When measuring the wavelength of EM radiation... what's actually being measured?"
] | [
false
] | So... I have two competing mental models of what EM radiation is from a mechanical perspective. (Turns out a "mechanical perspective" might not be possible which is... distressing.) OR: I must be wrong either way. Because we can these waves in terms of length, specifically in nanometers. I'm inclined to think that I'm ... | [
"I'm an EE grad student, who's specializing in microwaves and antenna theory.",
"So a good way to think about this, is that changes in the Electric and Magnetic fields don't propagate instantly; they travel at the speed of light. So if I turn on an electromagnet, it will take some time for any metal near it to fe... | [
"Before I try to answer your question, I think you're suffering from a (very common!) issue with your approach to physics. I've written a lot about this topic on Reddit before, so I'll link some comments: see ",
"here",
", ",
"here",
", ",
"here",
", and ",
"here",
". Though it's not directly connec... | [
"I’m going to jump into the meat of what you really want to know.",
"The question being, we're able to describe the physical wavelength in nanometers of these waves that apparently aren't oscillating in space so much as they oscillate between electric and magnetic fields. ...how do you assign a unit of length to... |
[
"Is there any hope that we will significantly decrease travel time to Mars?"
] | [
false
] | What is the theoretical minimum travel time, given today's technology and an unlimited budget? Would there be a significant improvement with new technologies such as nuclear rockets? Could you make an educated guess for the minimum travel time that we will ever achieve, in the far future? | [
"I'll leave it up to somebody else to calculate the fuel requirements.",
"Well, for starters, that's a pretty bad estimate of travel time for any remotely realistic trajectory or propulsion device, but since you asked.",
"For fuel estimation, that delta-V would be 626,000 m/s for each burn. The only propulsive ... | [
"I'll leave it up to somebody else to calculate the fuel requirements.",
"Well, for starters, that's a pretty bad estimate of travel time for any remotely realistic trajectory or propulsion device, but since you asked.",
"For fuel estimation, that delta-V would be 626,000 m/s for each burn. The only propulsive ... | [
"I suppose the fastest would be constant 1g acceleration when Mars is at perihelion and Earth is at aphelion and they are lined up relative to the sun. If someone could do the math, that would be nice.",
"EDIT: 1g because I don't think more than that is healthy for the human body."
] |
[
"Do beavers get splinters in their mouths, and if they do, how do they deal with them?"
] | [
false
] | I don’t know the specifics of beaver mouth mechanics or how they function when gnawing on trees, so, do beavers get splinters (small or large) in their mouth and if they do, how do they deal with them? | [
"They have two pairs of lips! One pair is behind their incisors that act as a barrier to protect them from both splinters and also swallowing too much water when they bring wood to their dam! Aside from their careful method of gnawing/chewing, beavers also tend to eat fresh or moist wood that help prevent splinters... | [
"I doubt they would build a dam in a lake. Scientists recently discovered the sound of rushing water is what triggers the dam building instinct. Like, beavers in an drained swimming pool with a bunch of wood and a speaker playing river sounds will build a dam on the speaker."
] | [
"It'd be hilarious if the only reason they build dams is they can't stand the sound. Burbling; the beaver's natural enemy."
] |
[
"Why aren't all amniotes classified as reptiles in the current taxonomic groupings? Couldn't we have just called sauropsids \"bird-like reptiles\"?"
] | [
false
] | Dimetrodons were called mammal-like reptiles for a long time before we began excluding non-sauropsids from the Reptilia grouping. Why didn't we just call sauropsids "bird-like" or "lizard-like" reptiles and synapsids "mammal-like reptiles" instead of going and excluding synapsids? | [
"For the most part, Reptilia just isn't really used as a formal taxon anymore. It may sometimes be used as a convenient grouping of more basal or less metabolically active amniotes, but in this way it usually applied to extant or recent groups (i.e., the classic collection of lepidosauria, turtles, and crocodilians... | [
"We're all just fish anyway. ",
"Seriously though, synapsids and sauropsids share a common ancestor but are two distinct monophyletic sister lineages. Synapsids gave rise to mammals and sauropsids to reptiles (including birds which are just highly derived reptiles). ",
"Your question just seems to be one of nom... | [
"Like ",
"u/DrDirtPhD",
" said, it wouldn't clear anything up. If we assigned all amniotes as reptiles that would make us ",
"reptiles",
" too (as it is, people have a problem with view birds as reptiles).",
"But also, the choices here are to help break the older ",
"\"ladder thinking\"",
" and simila... |
[
"Is it healthy for your skin/hair to shower daily?"
] | [
false
] | I have pretty dry skin, so I usually shower only every 2nd day. I alway thought that using body wash/shampoo too often drys out your skin. But I know from many people, that they take a full body shower every morning. I know there have been many general threads already asking redditors how often they showe, but I'd like... | [
"Perhaps it is, but surely you must agree that one case is not enough to base any sort of conclusion on. "
] | [
"That may be the case, Sir, but you are only one person under one set of conditions. Just because a data point (you) takes a long time to collect it doesn't make it more valid than any other. Maybe you just have good skin."
] | [
"http://www.abc.net.au/local/stories/2007/04/30/1887681.htm",
"Anecdotal, but tangentially related"
] |
[
"Why is Nitrogen Triiodide not soluble?"
] | [
false
] | We made Nitrogen Triiodide in our AP Chem class, for a demonstration, and now we have to write about why it's a good thing to do as a demonstration. We understand most of this, but what we don't understand is why it's not soluble in water. It has a lone pair, so it's polar, so why doesn't it? | [
"Hate to be pedantic on you but: Not soluble in what?\nIf you're talking normal organic solvents or water, probably gonna be to do with how massive iodine atoms are and how solvating them would take a lot of solvent molecules.\nAlso the lone pair doesn't impart the polarity, the electronegativity difference between... | [
"From what I can find on the topic it is soluble in organic solvents but insoluble in inorganic solvents. He did ask about solubility in water specifically though."
] | [
"From what i can find, it appears ",
"/u/oilyholmes",
" is correct. The shear size of the iodine, coupled with the fact that the electronegativity difference between the iodine and nitrogen is relatively small, makes it hard to solvate in water."
] |
[
"Does the cosmic event horizon or the particle horizon produce particles like a black hole?"
] | [
false
] | I was learning about the Unruh effect and I was told that all event horizons produce particles, so would that apply to any of the above horizons? | [
"Yes, a cosmological horizon will also produce particles, just like a black hole event horizon and the Unruh/Rindler horizon! This was also worked out by Hawking, in collaboration with Gibbons. ",
"Physical Review has made the original paper open access",
" in tribute to Hawking. "
] | [
"What is a cosmological horizon?"
] | [
"That’s what I thought, but this makes me even more confused, because this means everywhere is ”someones” cosmic horizon, thus this should be happening everywhere. What am I missing?"
] |
[
"What is it about cockroaches that makes them invulnerable to radioactivity, and can this somehow be manipulated and applied to humans?"
] | [
false
] | null | [
"As someone else mentioned, cockroach cells aren't dividing as frequently as ours, and cells that are dividing are the most sensitive to DNA damage from radiation. Humans die from radiation because of our most sensitive cells that are dividing the most frequently, our gut lining, and our blood stem cells. If you ... | [
"Cells in general are most vulnerable to radiation when they're diving. Cockroaches have cells divide once per week in a 48 hour period when they molt. ",
"http://www.bio.umass.edu/biology/kunkel/cockroach_faq.html#Q5"
] | [
"They are not as invulnerable to it as is made out, they are more resistant to it than humans but compared to other insects they are rather weak.",
"source, not the best but shall do for the moment till I find a better one"
] |
[
"why don't humans regenerate limbs?"
] | [
false
] | We all grew limbs when we were in the womb originally and from what I've heard after some amount of time there isn't a single cell that is still with us from before. Why can't we regenerate limbs? It seems that the ability is there to do so. and will science ever be able to progress to where we can regenerate limbs? | [
"In short, because the cells mature to a point where they lack the capacity to regrow. Remember, there are four tissue types involved in the process.",
"Epithelial cells by far would have the highest regenerative capacity, but remember, in a burn, if you lose the basal level, skin won't regrow. That's where the s... | [
"Salamanders are the most adept vertebrates when it comes to regeneration - many are capable of regrowing limbs, tails, eyes, etc. "
] | [
"In short, because the cells mature to a point where they lack the capacity to regrow. Remember, there are four tissue types involved in the process.",
"That's not the case in salamanders and other animals which do regenerate limbs. Muscle cells and other differentiated cells actually dedifferentiate into plurip... |
[
"Why do bases feel soapy or slippery (other than the fact that soap is basic of course)."
] | [
false
] | null | [
"When you touch a base it the fats in your skin to produce similar detergent compounds found in soap. Bases literally turn you into soap when they touch you. You are merely feeling the soap your skin has become."
] | [
"The process is called saponification, if you are interested. "
] | [
"Soap physically remove them from your skin, yes, but also kills microbes by destroying their cell membranes. "
] |
[
"How much do we actually see in the night sky?"
] | [
false
] | When i look at the stars how far am i seeing? | [
"Furthest away object is the Andromeda galaxy, furthest away star you could se under optimal conditions (apparent magnitude m=6) is about 15000 light years away. On average you can see maybe 500 light years or so.",
"For comparison, our galaxy is about 100 000 light years in diameter.",
"EDIT: Spelling."
] | [
"On average they are about 300 light years away. All the stars you see are in the Milky Way and the farthest would be about 1000 light years away. Any star you can spot has a Wikipedia page that will tell you more about it."
] | [
"And if you were lucky 06:12 UTC on March 19, 2008. You could have seen a gamma ray burst 7.5 billion light years away.",
"http://en.wikipedia.org/wiki/GRB_080319B"
] |
[
"Can brainwaves have a physical (or theoretical) wavelength?"
] | [
false
] | null | [
"wavelength = 1/frequency as always"
] | [
"Wavelength is ",
" to 1/frequency. What I would like to know is for example the the wavelength of the active visual cortex signals which tend to oscillate at around 40Hz."
] | [
"Duh sorry. I was having a total brain fart. ",
"Ok so ",
"here",
" (<- pdf!) is an article where they estimate brain nerve conduction velocity for some visual signals at 2-3 m/s. You can then use that to get the wavelength. "
] |
[
"Is it possible magnetic wormholes are responsible for how the sun's Corona works?"
] | [
false
] | null | [
"Physics"
] | [
"Physics"
] | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"/r/AskScience",
"For more information regarding this and similar issues, please see our ",
"guidelines",
"If you disagree with this decision, please send a ",
"message to the moderators."
] |
[
"When a star collapses into a black hole, why is there a super nova?"
] | [
false
] | My understanding is that, when a star collapses into a neutron star, the super nova is caused by the shockwave of the rebound as the matter collapses from atoms into neutrons. But for a black hole, surely there is no rebound, just a lack of outward pressure, in fact from the event horizon inwards no outward pressure at... | [
"Yes once the iron core starts collapsing the formation of a neutron star (core bounce) is inevitable: a neutron star is always formed at least temporarily. The only exception is for supermassive stars, stars with masses of the order of 10^5 Msun that might have existed in the early Universe. These are so compact t... | [
"Yes once the iron core starts collapsing the formation of a neutron star (core bounce) is inevitable: a neutron star is always formed at least temporarily. The only exception is for supermassive stars, stars with masses of the order of 10^5 Msun that might have existed in the early Universe. These are so compact t... | [
"The rebound and shockwave is caused by the infalling hydrogen from the surface layers of the star hitting the iron core of the star. The black hole is formed *after* the supernova. When a large enough star starts building up an iron core from fusion, the presence of that core stops the fusion (since iron can't be ... |
[
"For the biochemists. Is it possible for enzymes found in uncooked food or supplements to have digestive properties once consumed?"
] | [
false
] | I see these claims everywhere "This product contains enzymes which will help with digestion/absorption!" I understand that the acidity of the stomach denatures proteins, leaving them open for cleavage by pepsin at the amino end of aromatic amino acids. Are there many enzymes that do not contain aromatic amino acids and... | [
"I will preface this by saying I am a biochemist. \nFirst I'm curious if you have a specific food/supplement in mind.\nSecond it sounds like you've got a pretty good handle on what happens to proteins in the stomach. Enzymes like pepsin made in the stomach can survive the acidity. So if the food or supplement conta... | [
"Thanks for your explanation! As an example, let's look at Sun Warrior's \"Raw Vitamins For Her\". Their enzyme blend contains: Amylase, Cellulase, Protease, Lactase, Lipase, Maltase, Bromelain and Sucrase. Would these enzymes actually contribute to digestion if the product were taken with food (as is recommended)?... | [
"Enzymes which come from plants are apparently able to handle stomach acid reasonably well. So it would be important to check the source of the enzymes Sun Warrior is using.",
"amylase is a digestive enzyme in your salivary glands, your saliva contains it and helps to begin digestion even before food reaches the ... |
[
"Superfluids/Boson-Einstein substances... Can r/askscience explain them to me?"
] | [
false
] | I am truthfully unsure whether i should have posted this here or ELI5 because I have only high-school level intelligence. To the point: I was talking with a friend, and he mentioned that sometimes, as some elements approach absolute zero, the previously solid substance turns back into a liquid that is so volatile that ... | [
"There are two basic types of particles, bosons and fermions. Fermions include the particles we think of as matter, electrons, quarks (that make up protons and neutrons) and such. Bosons are exchanged in particle interactions: photons (light particles), gravitons (if they exist) and such. Both particles have a p... | [
"I'm not sure what your friend is talking about, but it sounds like a butchered version of superfluidity. It occurs in liquid helium, and below a certain temperature it loses all viscosity (friction for liquids). It demonstrates some ",
"interesting effects",
" in that state."
] | [
"Temperature as defined in physics is a rather non-intuitive quantity. It is defined as the rate of increase of disorder of a system per unit of energy added. Most thing tend to get disordered the more energy you pump in, but there are exceptions.",
"It ",
" possible to get ",
"some",
" systems to temperatu... |
[
"If the universe will forever keep expanding, until the visible universe for every individual particle is completely empty, What happens to all the potential energy?"
] | [
false
] | From my understanding, we on earth are only affected by gravity that emanates from within our visible universe. If the universe will forever expand, then particles will eventually be distant enough from one another to not exert any gravity on any other one. Is that energy lost? What happens to it? | [
"The energy is still there, it just can do no work. Look up: heat death of the universe."
] | [
"Gravity can apply to thermodynamics if it is a force which is doing work to generate heat in a system. By definition stated in your question, gravity no longer acts on any particle because they are too far apart. If there is no gravitational potential on any particle, then there can be no ",
" potential energy... | [
"I think I might have a better grasp on things now, thanks. ",
"In your last sentence I think you said better than I could have, what is the basis of my concern/question.",
"Now pardon me if I didn't understand correctly, but it seems as if the gravitational potential energy either just \"vanishes\", or it is t... |
[
"Does a condition in which the human body produces too much/more blood exist?"
] | [
false
] | null | [
"It depends on what you mean by “blood”. There are a number of components of blood, like red cells, white cells, proteins, and water, among others. ",
"Overproduction of red cells is called polycythemia vera. If, however, you are discussing the total volume of blood, an overall increase in total volume is most us... | [
"The other responses are good. I would just add that there are a few conditions that cause fluid retention (eg congestive heart failure) which can increase the pressure in the cardiovascular system. This increased hydrostatic pressure can be measured at the heart using echocardiography. Blood vessels are generally ... | [
"It does exist. I worked in the medical department onboard an aircraft carrier while I was Active Duty Navy some time ago. We had a guy check onboard midway through a deployment with chronic erythrocytosis (increased red blood cells) and needed to have his blood taken every 3 months.",
"This Sailor had checked on... |
[
"Snow on mountain tops"
] | [
false
] | [deleted] | [
"Oh wow, those are some stunning pictures! "
] | [
"Is it just due to the varying altitude of clouds? \nYes."
] | [
"Yes, you are right, there are several layers of clouds. \n",
"Here",
" are some pictures of my astronomy trip to La pama, its a high mountain at about 2.5km, and you can still see clouds above head. (Sadly most of them came when we tried to observe te stars -.-)"
] |
[
"Why is there a flu season, how does cold weather benefit the influenza virus?"
] | [
false
] | Why is the "flu season" specific to winter time? Also why does everyone make such a every year? If the flu season is restricted to specific months in the year why don't they plan ahead and get these required supplies of medicine in advance? It seems like every year around the same time they make a huge deal like it cam... | [
"The virus itself is probably less effective when cold, but cramming people indoors for three months straight helps it spread faster.",
"You can get the cold or the flu any time of the year.",
"It's also hard to \"plan ahead\" for a virus because it's constantly mutating into a new strain. Vaccines only work f... | [
"1 - People pack together, increasing chances of transmission just by proximity to new hosts. ",
"2 - the virus has ",
" a longer shedding period in cold, dry conditions, enhancing transmission. ",
"Here's a paper on it."
] | [
"Thank you for giving me enough info to track down a fascinating article I read about hunting down why the flu transmits faster in dry weather:",
"http://www.nytimes.com/2007/12/05/health/research/05flu.html",
"By varying air temperature and humidity in the guinea pigs’ quarters, they discovered that transmissi... |
[
"How do things like internal stitches not get rejected by the body?"
] | [
false
] | null | [
"The modern stitches used today are not rejected because get this: They are made out of animal collagen and decompose inside the body. How cool is that? Absorbable sutures are pretty amazing. The manufacturing of this material is able to be done to a degree that even their decomposition rate can be altered so they ... | [
"Just to further clarify what some poster already stated. There are stuff that can exists in the body that the immune system ignore. Stuff such are collagen, fibrin, other organic proteins that exits in the extracellular matrix, and of-course our cells.",
"Why? Because when immune cells are developing they are ne... | [
"To add to what's already been said about how the suture is made of absorbable materials, suture reactions and allergies can still occur, though they are fairly rare. ",
"Here",
" is a bit of info about suture reactions.",
"Also, sometimes non-absorbable sutures are used internally, but they are generally mad... |
[
"Why are youngest visible objects in space supermassive blackholes??"
] | [
false
] | [deleted] | [
"Younger in terms of the age of the Universe means farther away, which means objects need to be really bright in order to see them. A single star, for example, is incredibly faint and wouldn't be detectable, though people are looking for certain types of massive stars that ",
" make up the first generation of sta... | [
"What's weird is how come there aren't any of these things right near us? Or is it because if there were, we'd be blasted away?"
] | [
"You wouldn't want the supermassive black hole at the center of our galaxy to be a quasar, no. But it's not that weird that there aren't any near us. The closer things are, the later you are in cosmic time, so all this is saying is that quasars \"turn off\" as you get closer to the present time."
] |
[
"How do 3D TVs work?"
] | [
false
] | How do 3D TVs work with modern glasses? Also, is it possible to make 3D TVs work without the glasses, if not, are we close in technology to make it possible? | [
"3D technology (in general) works by sending two slightly offset images, one to your left eye, and one to your right. Your brain interprets the two images as one, and uses the slightly different perspective to determine distance. ",
"All 3D screen technology accomplishes the same goal of sending a different image... | [
"Some TVs also use(d?) the polarisation system."
] | [
"One of two ways. One is by using an LCD light shutter on the special glasses. The TV alternates left/right images at tens of times a second. Fast enough your persistence of vision lets you see one continuous image. ",
"Another way is to present two video displays, overlapped. But with one optically polarized one... |
[
"What frequency if any do standard magnetic fields produce?"
] | [
false
] | Two questions. Typing these search terms in Google make it difficult to find the answers, and I've learned so much ever since subscribing to this sub so I know someone here knows this. 1: are magnetic fields electromagnetic, or is there a separation between electricity and magnetism? I have a rough understanding of pho... | [
"Question 1. Static magnetic fields are a special case of electromagnetic fields where there is no associated electric field. Changing magnetic fields always have accompanying electric fields. Therefore, changing magnetic fields are just the magnetic component of the overall electromagnetic fields. Note that a magn... | [
"There is no such thing as purely radiated \"magnetic waves\" and my answer did not imply that. When it comes to radiated energy, there are only regular \"electromagnetic waves\". When a magnet is moved around, it creates regular electromagnetic waves, because the changing magnetic field creates an electric field, ... | [
"Thank you very much for this, it ties together a lot of what I've learned. \nFollow up question, when you say they create low frequency radio waves, do you mean it along the lines of microwaves for example being high frequency radio waves, or are magnetic waves indeed radio waves? I understand that below radio wav... |
[
"Did the methane produced from bison have as much of an impact as the methane produced from cattle farming today?"
] | [
false
] | Did the methane produced from bison have as much of an impact as the methane produced from cattle farming today? I don't know much about climate change, but I obviously believe in it. Now, I've heard this talking point before and thought it was one of the few that gave me pause. I'm curious is there is some difference ... | [
"In short, no. Now, in terms of the amount of methane produced, comparisons of cows (specifically, cows in feedlots) with bison, suggest that on a per animal basis, they may produce roughly comparable amounts of methane (e.g., ",
"Stoy et al., 2021",
"). If you look through that paper though, they highlight a l... | [
"For point 1 - there is some uncertainty here, so we want to be careful about directly extrapolating.",
"For point 2 & 3 - do you have a source that specifically only US cattle production is the main issue? I.e., restricting the comparison of methane emissions from one livestock species of one country is problema... | [
"There’s something I don’t get. Here are the points you made:\n1) bison & cattle produce similar levels of ch4\n2) 30 million bison being killed did not make much of an impact. \n3) the 90 million cattle in the US today have a huge impact.",
"Should the extirpation have been 1/3 the impact of the beef herd today?... |
[
"What material are atoms made out of?"
] | [
false
] | So basic knowledge of atoms states that under a specific configuration of protons, neutrons and electrons, an atom can theoretically be anything in the periodic table, just like hydrogen in a star can be fused to heavier elements but what exactly are subatomic particles made of ? Not in the sense that a proton is made ... | [
"To the best of our knowledge is no common \"stuff\" that ",
"elementary particles",
" are made of. In fact this is why they are called elementary to begin with in order to denote that they are the building block out of which everything is made. The most concise description I can give of the zoo of elementary p... | [
"/u/crnaruka",
" gives a good, thorough answer, so I'll fill in a little bit from a different angle on your question.",
"The properties of a material (we'll use gold as an example) are determined by the structure of its atoms' electron clouds, which basically boils down to \"how many electrons does it have?\" ... | [
"In a fundamental sense, this is what matter is. It is a bound, localized, excited state of multiple particle fields, the nature of which is described by the interactions operating within fields and between the fields. ",
"Thank you! Your explanation was clear and easy to understand, but the conclusion is awesom... |
[
"Car engine: why does shifting up earlier/lower rpm consume less fuel?"
] | [
false
] | In racing it's said that when you shift earlier you consume less fuel - even though you floor the gas anyways, so what makes the engine use less fuel? | [
"My best guess is that by shifting earlier you don't let the engine rpm get super high, therefore reducing amount of fuel per second consumed. But by doing this you also lose out on the high rpm power range. If the engine is built correctly (cams etc), you can effectively shift the rpm where the engine has maximum ... | [
"Lower RPM equates to less cycles (four strokes) for a given amount of time in a typical ICE.",
"Each cycle consumes a given amount of fuel to burn the amount of air in a cyclinder. Since down-shifting increases RPM, you're burning more fuel to compensate the increased amount of air going into the car in a given ... | [
"Fuel engines have a maximum torque at a certain number of rpm. So if you want to accelerate fast (e.g. in races) you want to have maximum torque for as long as possible.",
"Let's say you have a regular car, then the maximum torque is typically at around 4k rpm. If you want to accelerate fast, then you want to st... |
[
"Why aren't there freshwater whales/dolphins/other mammals with similar features?"
] | [
false
] | [deleted] | [
"Fresh water dolphins",
" are found in many of the largest river systems on this planet. "
] | [
"Yeah I actually saw those after I posted it, but I was still thinking along the lines of small ones, along the lines of the size of fish like trout. "
] | [
"I remember reading that hippos are close relatives of whales. They live in lakes and rivers and are friggin' huge!"
] |
[
"What on earth will we do with regards to plastics once we've run out of oil?"
] | [
false
] | [deleted] | [
"I believe it was Sheikh Yamani when he formed OPEC, when asked \"When will we see the end of the age of oil?\" answered \"The Stone Age didn't end because we ran out of stones.\""
] | [
"at the end of the day plastic is just another hydrocarbon. It may cost more to generate it from a non-oil source, or at least some costs to research how to do so, but I'm sure we'll keep going. We have ",
" of carbon and water on the planet in one form or another.",
"Also: common misconception/poor word choice... | [
"http://en.wikipedia.org/wiki/Bioplastic"
] |
[
"Why do older end stage renal disease (on dialysis) patients have blue eyes?"
] | [
false
] | I'm a second year PA student doing rotations and seeing dialysis patients. I've noticed that many of the older black patients have blue irises. What causes this? | [
"That’s called arcus senilis. It’s not the iris that takes on the blue color. It’s the cornea itself that becomes discolored with age due to deposits of lipids (fatty substances.) I think people with hyperlipidemia are more likely to get it. So it’s a population that is also prone to kidney failure resulting from ... | [
"Any chance it could be this and/or corneal calcifications? "
] | [
"Yeah. There are other conditions like corneal calcification and cataracts that can make the pupils look funny. I would have to see the patient to offer an opinion. arcus senilis is the common thing though. "
] |
[
"Will a hot drink in the fridge get colder faster if I put a metal spoon in it?"
] | [
false
] | I did this one and I think it have happened. I tried to figure it out with my roommates but eh. | [
"Depending on how much of the spoon stuck out, it would work as a radiator somewhat. Heat would conduct up the handle and radiate out into the freezer itself. It's giving two key features: it's made of metal, which conducts heat well, and it's providing more surface area for the heat to radiate from."
] | [
"I did some quick calculations.",
"Cup Diam= 0.1m\nCup L= 0.15m\nTcup=80 C = 353 K\nTfreezer = -20 C = 253 K\nemissivity ice, e1=.98\npyrex e2=0.90",
"Control volume around the surface of the cup.",
"dE/dT=-qrad-qconv-",
"Assuming that resistance between ceramic and water is negligible, ignoring conduction ... | [
"It would act to conduct heat more quickly from the hot liquid because metal is a better conducting agent than the liquid. You are also increasing the surface area of conduction by adding the spoon. The effects might be minimal for a spoon. For a better test, take large piece of aluminum foil and stick it into the ... |
[
"How is it possible for muscle to grow larger (weight lifting) during a caloric deficit?"
] | [
false
] | I thought you needed a caloric surplus to form larger muscles? For clarity I mean a daily, regular deficit of calories. | [
"There is a difference between peak muscle growth and suboptimal muscle growth. The different is simply the rate at which muscle is built, and it is regulated by available materials.",
"On a caloric deficit you are still taking in protein, fats, and carbohydrates to fuel your body and give it the building blocks ... | [
"This was very informative, well stated and on-topic. Thank you!"
] | [
"This isn't really a scientific answer, but based on experience. You don't really gain muscle or strength on a deficit if you're an intermediate or advanced lifter. This will usually only happen and untrained beginners who are on a deficit, but have never lifted before. Also, ",
"this is worth reading"
] |
[
"Why are most drones quadcopters while full scale helicopters tend to be monocopters?"
] | [
false
] | null | [
"Because they can do everything they need to do solely by altering the speed of the motors.",
"With just one rotor, all the drone could do is go up and down. And the problem with any odd number of rotors is that you can't neutralise the torques in pairs, so the drone body will spin (helicopters counteract this wi... | [
"Because they can do everything they need to do solely by altering the speed of the motors.",
"With just one rotor, all the drone could do is go up and down. And the problem with any odd number of rotors is that you can't neutralise the torques in pairs, so the drone body will spin (helicopters counteract this wi... | [
"To change rotor lift quickly, you need to have variable pitch blades. A large rotor wouldn't be able to speed up and down fast enough to control lift. If you have variable pitch blades, you might as well add cyclic control. Now you're at a point where it makes more sense to just have one large set of complex rotor... |
[
"How does modern colorization of black & white film photographs or moving pictures work?"
] | [
false
] | Is it merely guesswork, or are certain shades of grey able to be precisely equated to certain colors? I would imagine that would require the ability to precisely re-create the lighting scenario of the original, which seems unlikely to be possible in nearly all situations. I'm familiar with early techniques such as usin... | [
"Actually not a science question in the typical sense.",
"The process is indeed the same as always, although the tools have become more advanced.",
"Today it is relatively straight forward in color correction software to change the color of an object. Usually this is changing a car from red to blue or something... | [
"Somewhat tangential, but ",
"this is a good article about determining the color of a jersey in a black and white photograph",
". ",
"It discusses using color charts produced in that era to guess what a color actually is, limitations of film formats, and how actresses wore yellow lipstick which actually appe... | [
"Put it in science as I was figuring there was a bit more of the physics of light at play to pull out some \"authentic\" elements or something. Sounds like it's really more of a human-eye and guess it thing, with computers then just being good enough to apply to moving objects across frames for multiple images if n... |
[
"How exactly are bosons derived from \"connection fields\", and how are connection fields derived from symmetries?"
] | [
false
] | How exactly do symmetries in particle physics, and the breaking of those symmetries, lead to connection fields? Are these fields basically just implementations of the 'rules' that must be followed as a result of a broken symmetry? What exactly IS a broken symmetry, and how is the Higgs field responsible for breaking sy... | [
"The main object in quantum field theory is the ",
"lagrangian density L",
" which is an energy measure. If there are things you can do that leaves L invariant (i.e. it doesn't change), then you have a symmetry. ",
"As an illustrative example, let's say the lagrangian only consisted of length of vectors. If y... | [
"The lagrangian used in QFT (hence the one I talk about) is the lagrangian density where you get the lagrangian L by integrating over all space.",
"Also, what you say about the lagrangian not being energy, that's exactly why I said energy measure and not the energy. This detail wasn't very relevant for my story."... | [
"If there are things you can do that leaves L invariant (i.e. it doesn't change), then you have a symmetry. ",
"of course you know this but it's not L that has to stay invariant but the integral over L (\"the action\"). of course this is trivially true when L is invariant."
] |
[
"Is it possible that after thousands of years of having humans as riders, some geographical horse groups have anatomy evolved to better suit themselves for humans to ride them?"
] | [
false
] | null | [
"Actually this probably wouldn't have to take thousands of years, with the way we breed horses. If we were to find a type of horse that was more suitable for us to ride, we would then breed that horse with other horses trying to keep the trait that we like."
] | [
"I didn't even think about selective breeding, but good point. "
] | [
"Horses were completely different to their current for before we domesticated them."
] |
[
"When you pull apart a pair of quarks, how can another pair of quarks be spontaneously manufactured from the energy you put into them?"
] | [
false
] | null | [
"Simultaneity doesn’t really have anything to do with it."
] | [
"How so? I learned that it is impossible to isolate a single quark. So when the pair becomes separated, does it instantly create the sister particles or is there a delay?"
] | [
"Quantum-mechanically, the exact “time” when it happens is not really well-defined."
] |
[
"What does it mean that homosexuality is “just” partially influenced by genetics? How environment shapes sexual orientation(i.e. Homosexual/homophobic parents et cetera). (Of course I’m sorry if it sounds offensive, I’m genuinely interested)"
] | [
false
] | null | [
"So first things first, the way we do this type of research is usually with a method call genome-wide association study ",
"(GWAS)",
". The idea is that while it is expensive to sequence the entire genome of a lot of people, you can just look at small portions of the genome of a lot of people and have a pretty ... | [
"Thank u for your reply, it was really clear! I think that the polygenic theory is reasonable, because many behaviours are influenced by genes, but trying to find their roots in just one gene isn't wise. I find fascinating the relationship between genes and environment, especially in a context like human psychology... | [
"In biology we talk a lot about ",
"GxE",
" interactions, which is the keyword you are looking for here."
] |
[
"/r/askscience, I'm scared. Please tell me this (and the comments, about bulk methane release) are mistaken in their facts somehow, and we aren't --><-- close to an extinction level event."
] | [
false
] | null | [
"Well, you could take comfort from the fact that ",
"we have very frequently as a species been convinced we're all about to die any moment",
", yet we're still here."
] | [
"Why?"
] | [
"I'm not sure. The possible scope of this fucking disaster could kill off a large percentage of sea life, that would affect the food chain and no one would be unaffected by it."
] |
[
"What is the current state of CO2 removal using direct air capture?"
] | [
false
] | I have a lot of questions about removing CO2 from the environment, but let's focus on this one: Additional questions: When I google, I get some company websites, so at least it seems profitable/a good story for investors, but that does not tell me much about the future of these technologies. Looking forward to your... | [
"Right now, we have several CO2 reduction technologies ready to go. Starting with the most cost-effective, and omitting the \"use less\" scenarios:",
"Replacement of fossil fuel power plants with carbon free electricity such as wind and solar power (also geothermal, where possible and nuclear, where palatable). C... | [
"In summary: the best thing you can do, apart from causing less emissions, is plant a tree.",
"But you have to make sure that eventually, the tree becomes buried without rotting or burning, or is replaced at its death with another tree, so that the carbon ",
" captured. And if you replace it with a 2nd tree, yo... | [
"Tree carbon calculations are always weird and filled with variability based on the life of that tree; ",
"Plant a tree. Gets eaten by a deer or moose within a week. No sequestration.",
"\nPlant another tree. Grows to maturity. Dies in fire. Sequestered for the life of that tree.",
"\nPlant another tree. Gr... |
[
"If a supersonic engine was attached to commercial airplane, would the plane be able to fly?"
] | [
false
] | Hence, the plane would be flying in supersonic speed. normal airplane as in commercial plane, boeing 747 etc. | [
"When you start reaching critical mach speeds, which is the lowest speed at which some air passing over the aircraft starts travelling supersonic, (wings work partly by speeding up air over the wing and slowing it under the wing) most conventional aircraft will create so much drag that supersonic flight will either... | [
"Bingo. We design structures, hardware, controllers, and outer mold lines of things like the wings, control surfaces, fuselages, etc very differently for supersonic vs. subsonic or even high subsonic/transonic aircraft. There are a lot of things you can get away with or want to exploit on a subsonic plane that supe... | [
"Yeah, The reason it happens is because the increased drag will cause the wing to actually twist when you deflect an aileron, turning it effectively into a giant aileron going in the opposite direction. "
] |
[
"Can someone explain the practical use of control engineering?"
] | [
false
] | How are concepts such as polar plots,root locus plot,nyquist criterion,signal flow analysis etc applied practically to a feedback loop? I mess around with arduinos and have constructed few closed systems such as encoder-motor, heater-thermal sensor. | [
"a very simple explanation is those values define the behavior of a system and adding a feedback controller adds a new term to the equation. By selecting a specific controller behavior, you can tune the whole system to behave how you want it to.",
"For example, you have a mechanical system like an inverted pendul... | [
"Well first it helps to know like what sort of process is being controlled:",
"Proportional (P) control is useful for controlling variables that respond directly (usually multiplied by some constant) to some control action you apply. For a very simple system like controlling a rate of flow, you could just increa... | [
"Most of that mathematical calculation is useful either in theoretical applications where one is trying to push the limits of controls or after 48 hours with no sleep trying to figure out why your control system is blowing up repeatedly under what should be stable conditions.",
"That is to say that a practicing c... |
[
"I don't have a dishwasher. If I just rinse my plates and silverware without using soap, what negative consequences am I exposing myself to?"
] | [
false
] | null | [
"I'm not fully qualified to answer this, but it's an excellent question. ",
"Cleaning something requires energy. We typically provide energy to the cleaning process in three ways: ",
"If you remove one of these energy inputs, you can generally make up for it by increasing the others. That is, without soap you'l... | [
"At faucet temperatures and normal dish cleaning times, heat doesn't kill bacteria. In this study, below 53C didn't hurt e. coli or salmonella, 54C for 120 seconds caused \"sublethal injury\", and it took 54C+ water for 180s+ to reduce bacterial population. (",
"source",
". Rather, heated faucet water can melt... | [
"There is an indirect benefit in terms of anti-bacterial results, though. Removing bits of food more easily also removes the growing conditions for bacteria. If you aren't cleaning thoroughly enough, you're providing a breeding ground for bacteria."
] |
[
"Why can't you look at the sun?"
] | [
false
] | Why does the sun, or bright light seem to overwhelm the eyes? | [
"The amount of light hitting the receptors at the back of your is too great when looking directly at the sun. If you take a quick glance, you will notice that a dark spot stays in your vision for a moment. That dark spot is your receptors in a sort of \"knocked out\" stage. If you look for too long, it will burn ou... | [
"By energy, I don't mean we can't process that much, it's a physical thing.",
"Let me use a simple analogy that might make it easier. Imagine a garden hose. it normally allows lets say 1 litre of water per second to pass through it. That's the receptors in the back of your eye. Now, imagine that instead of the ta... | [
"nah, i've looked directly at burning magnesium before- it left a blind spot for a few minutes, but nothing permanent. well, it got me permanently kicked out of my high school chemistry class, but my eyes are fine."
] |
[
"What makes Mount Everest so deadly?"
] | [
false
] | Assuming an average Joe with no training had all the right supplies and permitting no natural disasters occurred, why is considered so likely he would die climbing the mountain? Is it natural disasters, climate, temperature? Does it have to do with pressure exposure to the altitude? Thanks in advance, I'm just having a... | [
"Even below the death zone, Everest climbers have to deal with both ",
"acute",
" and ",
"chronic",
" altitude sickness, so their judgement may be impaired ",
" they even attempt the summit. ",
"As for what happens in the death zone... Hold your breath. Keep holding it. Dizzy yet? Keep holding it.... | [
"Humans are not designed to be above 25,000 ft elevation. They slowly die up there.",
"Amateurs don't have the training to deal with rope lines and rope bridges and crest paths at that elevation.",
"Given all the money it costs, guides are super motivated to get all their amateurs to the top. So they take risks... | [
"Everest is not a particularly technical climb (i.e. there are no really hard parts where skilled climbing techniques are needed). It's really just a very long and steep hike. However, being the highest peak on Earth makes it a huge draw for \"advanced tourists\". A lot of people who are not climbers by inclinat... |
[
"If you make a nuclear weapon with a small blast wave would it still produce a mushroom cloud ?"
] | [
false
] | null | [
"No. The mushroom cloud is simply a result of an explosion with large enough yield. A large enough conventional explosion will create one, a small enough nuclear weapon will not. The 11 ton yield of the MOAB is sufficient.",
"It might be hard to build a nuclear weapon with a low enough yield with today's technolo... | [
"Even very small conventional weapons produce something that has a \"mushroom\" appearance. But as you lower the energy release, you lower the heat and volume of the cloud. So small explosions don't rise very high (the heat) and they don't contain as much material (the volume), and as a result they blow away very q... | [
"You just reduce the amount of fissile material. Average yield on a modern us nuke is something like 6.6kt per kg. That's OSINT.",
"",
"The mushroom cloud really depends on the environment for smaller explosions because you are dealing with a pressure wave expansion, a thermal vacuum, the ingestion of material... |
[
"Why do Side Bands exist in AM radio?"
] | [
false
] | I'm struggling to understand why side bands occur. Usually the explanations I see online just say "because of the math" and leave it at that. If AM changes the amplitude of a signal, why does that cause a signal on the wavelengths above and below the carrier frequency? | [
"You have your carrier frequency, say 1mhz.",
"This is a sine wave at 1mhz.",
"A spectrum analysis would show a spike at 1mhz.",
"When you amplitude modulate it, with say your voice,",
"you no longer have the simple, single spike.",
"You have harmonics above and below 1mhz.",
"These are the upper and lo... | [
"AM just works by multiplying the signal by a constant-frequency cosine wave. So if the signal you're trying to transmit ranges from, say, 0Hz to 20kHz, you should intuitively expect the modulated signal to spread out by roughly the same 20Khz.",
"In fact, the spread is ± 20Khz, for a total of 40Khz. This is \"... | [
"\"Shifting the signal\" means that you add a constant to it, so that the signal becomes positive. For instance, if the signal is cos(at), which is negative half of the time, then it could be shifted to 1+cos(at), which would make it positive.",
"This is done to make it easier for the receiver to tune in on the c... |
[
"Is water the second most common molecule in the universe?"
] | [
false
] | I stumbled across this statement, but couldn't find any reputable sources that could confirm it. If I understand correctly it's much easier to estimate abundance of chemical elements in the universe that it is to estimate abundance of molecules? Are we able to estimate distribution of molecules in the universe? If yes ... | [
"The second most common molecule in the Universe is CO, carbon monoxide. ",
"The most common molecule, by far, is H2, molecular hydrogen. We normally study atoms and molecules in interstellar space by looking at the ",
"spectral lines",
" they emit. However H2 doesn't really have any spectral lines, unless it... | [
"The most abundant elements are hydrogen, then helium, then oxygen. Helium can't be used in any molecules, so it can be ignored. Hydrogen on its own can't produce any molecules but hydrogen. Oxygen mixed with huge amounts of hydrogen is going to make water. I'd say it's pretty clear that that would be the second mo... | [
"Thanks a lot for digging up this thread and taking your time to answer, this helps a lot."
] |
[
"How is oxygen dissolved in water and what is a simple and efficient method of accomplishing this?"
] | [
false
] | There seems to be much confusion on some of the forums that I follow as to exactly how oxygen is dissolved in water. Some say oxygen in bubbles from an airstone will dissolve into the water as they float upward. Others say it is the breaking of the surface tension that causes oxygen to dissolve. How exactly is oxyge... | [
"The rate of mass exchange from a gas to a liquid (or vice versa) is related to the the difference in concentration of the chemical of interest, the surface area for transfer, and the mass transfer coefficient. ",
"rate = k*A*(C* - C)\n",
"Henry's Law",
"For your case, you aren't controlling either concentrat... | [
"Try a ceramic air stone with your pump, it creates very small bubbles that oxygenated quite well. Downside is they can be a little on the spendy side (comparatively), and fragile.",
"Source: I own a retail store that sells all of these things."
] | [
"Homebrewers are very interested in this question, as we routinely saturate liquid with oxygen. I believe the number, 40ppm, is easily reached using a 0.5 micron steel diffusion stone in about one minute. I don't know much about the Venturi devices, but the diffusion stone method is very quick and easy."
] |
[
"What would happen if you put an egg in a vacuum chamber, or into space?"
] | [
false
] | null | [
"A pickled egg would be interesting to watch.",
"The vacuum of space isn't the ultimate exploding force that some movies make it out to be. My intuition says the egg holds.",
"This can be replicated on earth pretty easily. I wonder if the surface scientist where I work will let me use one of his high vacua..."
... | [
"I agree, although I only have intuition. Speculation on the whites/yolks freezing in space is unlikely in the short term due to the slow transfer of heat.",
"I wonder if the result would be different if we removed the shell with vinegar first."
] | [
"Nothing dramatic. Maybe the UV from the sun would scorch the shell. "
] |
[
"Is there skepticism of quantum theories and quantum computing in the scientific community?"
] | [
false
] | null | [
"Quantum mechanics simply cannot be properly explained in English. What happens is that people hear vague descriptions and analogies because that's all we can really do without the math. Then people take that and think they can reason about quantum mechanics in those terms. You can't. The math is just too strange, ... | [
"Quantum mechanics simply cannot be properly explained in English. What happens is that people hear vague descriptions and analogies because that's all we can really do without the math. Then people take that and think they can reason about quantum mechanics in those terms. You can't. The math is just too strange, ... | [
"Your friend is mistaken. ",
"Bell's Theorem",
" tells us that there cannot be \"local hidden variables\", i.e., it's ",
" just the case that a particle has spin A and we don't know it yet, unless there is some sort of global universal \"state\" hiding it."
] |
[
"What do ants do with the corpses of their fellow ants?"
] | [
false
] | I have witnessed, numerous times, ants on a trail coming back to retrieve the dead bodies of their fallen comrades. What do they do with them? | [
"What you're witnessing is a hygienic behavior called necrophoresis",
" in which colony members actively remove their dead nestmates and place them either in a particular location outside the nest (in a type of \"graveyard\") or simply scattered about a certain distance away. The idea is to prevent the further sp... | [
"Ants are capable of picking up on very minute chemical cues. If a nestmate dies, it will start to release a distinct odor into the nest. Other ants will recognize the smell, realize what it means, and act accordingly. Such behavior is quite hardwired, so to speak. In fact, you can take a live ant and spray it with... | [
"Are ants that smart? Is it their natural instinct?"
] |
[
"In Newtonian mechanics mass(m), momentum (mv) and kinetic energy (1/2 mv^2) are conserved. Are the further integrals wrt velocity also conserved?"
] | [
false
] | Every good high-school physics student learns that in Newtonian mechanics that various things are conserved in any system*, namely: The more observant (and better taught) might even notice that these are the zeroth, first, and second integrals of mass wrt velocity. I finally grokked this properly (20 years after high-s... | [
" Momentum and kinetic energy are not necessarily conserved, and the precise statements regarding their conservation are contained in equations that describe what could possibly cause them not to be conserved. We can obtain similar conservation laws for higher moments of velocity (the third moment is related to hea... | [
"For instance, in a two-body gravitational system, neither momentum nor kinetic energy is conserved. ",
"Just to clarify, this would only be true if the system is either one of the bodies. If the system is the pair of masses then momentum must be conserved."
] | [
"I could be wrong, but I think kinetic energy and potential energy are found by integrating Newton's 2nd Law",
"KE = int/ ma dx = int/ mv dv/dx dx = int/ mv dv = 1/2 mv",
" (+C)",
"(Note a = dv/dt = (dx/dt)(dv/dx) = v dv/dx )",
"ma - F = 0",
"int/ (ma - F) dx = int/ 0 dx",
"int/ mv dv/dx dx - int/ F dx ... |
[
"How do we determine the habitable zone of a star that is lightyears away?"
] | [
false
] | How do we measure things like this? | [
"We can calculate the average temperature of a planet given its size, ",
"albedo",
", distance from the star and the star's luminosity. The habitable zone is simply defined as the range of radii in which water would be liquid at this temperature."
] | [
"So technically the habitable zone of a star could be totally un-inhabitable but as long as the temperature is correct for water to exist in liquid form it's considered the habitable zone?"
] | [
"The habitable ",
" is always habitable, in the sense that if the right kind of planet happened to be there it could have liquid water on its surface. However not every star will have planets in its habitable zone, and not every planet within the zone will be habitable. It might be too small (like our Moon) and b... |
[
"AskScience AMA Series: I'm Robbert Dijkgraaf, mathematical physicist, author, and director of the Institute for Advanced Study, here to answer your questions about the math and physics of the universe and Big Bang. Ask me anything!"
] | [
false
] | This is Robbert Dijkgraaf, Director and Leon Levy Professor at the Institute for Advanced Study, one of the world's foremost centers for curiosity-driven basic research, located in Princeton, New Jersey. I'm a mathematical physicist specializing in string theory, and my research focuses on the interface between mathema... | [
"There’s only one time in the history of the world that we see an image of the black hole for the first time. NOW is that moment. We’ll remember this far in the future. And we were all around in 2019!!!"
] | [
"Hi and thanks for joining us today.",
"I have a difficult time even conceptualizing the Big Bang, could you elaborate on how it was an explosion ",
" space and not an explosion ",
" space."
] | [
"I'll take the last 5 years!",
"Exciting ***** moments in physics last 5 years (in order of discovery)",
"Higgs particle",
"Gravitational waves, including colliding black holes and neutron stars -- might be 6 star ;-)",
"The M87 black hole image for sure!",
"All of them took a long time from idea -> exper... |
[
"Will I damage my Li-Ion cell phone battery if I charge it every night?"
] | [
false
] | null | [
"Short answer: No.",
"Long answer: Cell phones have pretty sophisticated charging circuits designed to treat the battery well. I think you are asking this question because you are actually considering three options - \n* A. Plug in my phone every night.\n* B. Plug in my phone every other night, or even less ofte... | [
"I do research on Lithium-ion batteries as a PhD student. There are several ways in which Li-Ion batteries degrade, but the big ones are mechanical degradation/fracturing of the Electrodes on a microscopic level, and undesirable side chemical reactions.",
"When Lithium ions intercalate/deintercalate into the elec... | [
"Thanks for trying, but please try to keep speculation and I've-been-told stories off of AskScience. Have a nice day! :D"
] |
[
"Why does adding air to a tire not add weight?"
] | [
false
] | I once had this explained to me, but it way to technical of terms (meaning I'm bad at science). What about tires filled with nitrogen? Does that make the tires lighter? | [
"It does add weight, just not a whole lot of it.",
"http://www.ehow.com/how_7189945_calculate-mass-air-air_filled-tire.html"
] | [
"Adding air ",
" add weight. Whoever explained it to you before was wrong. ",
"Air has mass. If you add more air to the tire, the total mass of the system increases. Same goes for nitrogen. "
] | [
"What about tires filled with nitrogen? Does that make the tires lighter?",
"Air is mostly nitrogen gas. The pressure you'd fill it up to would entirely determine if it has more mass."
] |
[
"Is organic milk better than regular non-rBGH milk for my child?"
] | [
false
] | My daughter is 6 months old, and we will soon start adding some cow milk to her diet. She quit breast feeding after about 2 months and has been on formula since. Now that much of the non-organic milk we buy is non-rBGH (I know the effect of hormones are debated as well, but it can't hurt to avoid the rBGH milk), is t... | [
"There are no studies that I am aware of that show a health benefit to organic over traditionally managed crops. ",
"There is a ",
"recent",
" study on organic vs traditional milk that basically concludes that year and season (i.e., winter vs summer) have a greater impact on milk nutritional value than farm m... | [
"It's unlikely that rBGH has any effect on human health and development, but if you're going to be feeding your infant organic milk, please be responsible and make sure it's adequately pasteurized."
] | [
"Thanks for the links, most of the google stuff is very sensationalist one way or the other. "
] |
[
"How do wild animals know which mushrooms are safe to eat and which are toxic?"
] | [
false
] | Or do they just avoid mushrooms completely? | [
"As my Biology professor repeated over and over throughout the semester, \"",
" ",
", ",
" ",
".\""
] | [
"We actually just talked about this in a way in my Animal Behavior class Tuesday. We didn't cover the genetics of it, just learning though. This isn't a total answer but it can maybe answer a little bit of your question.",
"It's called Conditioned Taste Aversion. It is similar to classical conditioning, but usual... | [
"Regarding the \"almond smell\" thing people are talking about: lots of poisonous things \"smell like almonds,\" because they smell like ",
". That's \"bitter almond smell\". Wild almonds and many other poisonous things that \"smell like almonds\" contain cyanide. The domesticated kind of almond does not, and it'... |
[
"When I'm doing the dishes, why does hot water make things stuck to the plate unstick?"
] | [
true
] | [deleted] | [
"Organic substances tend to be comprised of polar molecules, which enables them to bond lightly to other objects through ",
"Van der Waals",
" bonding. Water, as another polar molecule, has the ability to disrupt those bonds by adsorbing to the organic substances in place of the plate."
] | [
"To elaborate a bit on what this excitement does:",
"Many food fats are solid at cold temperatures and liquid at hot ones.",
"Think melting butter or freezing ice-cream."
] | [
"The heat energy in the water excites the components of food and oils so they can be lifted up easier using something abrasive."
] |
[
"Combining AM and FM"
] | [
false
] | Please excuse me if my question turns out to be completely out to lunch. My question is this. Since AM modulates the amplitude of a carrier wave to transmit information and FM modulates frequency, is it possible to combine both AM and FM on the same carrier wave? Essentially modulating frequency and amplitude simultane... | [
"This is almost what quadrature amplitude modulation (QAM) is, except QAM uses a combination of amplitude modulation and phase modulation.",
"On a side note, if it were possible, would it be capable of transmitting seperate information?",
"Sure"
] | [
"Is the phase modulation part for digital information?"
] | [
"You could do that, but generally the information is either all analog or all digital."
] |
[
"Why is it that we can get sick for eating things that are full of germs, like stuff dropped on the floor etc, but not from all the nasty bacteria and such that is in our mouths already?"
] | [
false
] | null | [
"The answer is simple: If you are healthy, those bacteria that already inhabit your mouth, skin and intestine are not nasty at all. Actually they are very useful. Without a normal gut flora you would not be able to absorb all the essential nutritions in the food for example. You have more bacteria in your body than... | [
"As long as the bacteria stay in your mouth, they are not nasty at all, because we need them there. If they got into a wound the story is quite different. Your body will not tolerate any cells other than its own inside you (and by inside i mean intraperitoneal space, blood, tissue, organs etc, not counting the inte... | [
"This. Remember that all the bacteria that live on/in us are separated from our tissues by our epithelial barrier. If one person bites another they are causing a breach in that barrier and introducing bacteria which can cause infection. 20% of all healthy individuals carry S. aureus in their nasal cavities, this is... |
[
"[Physics] What happens to the kinetic energy in a car involved in a crash?"
] | [
false
] | If a 1300kg car is travelling at 100km/h and the brakes were applied until it stopped, its kinetic energy would been directly turned into heat in the braking system (mainly in the discs and pads). If the same car hit a solid wall at the same speed, obviously the energy dissipates through the car as it crumples, but wha... | [
"A crashed car will indeed be hotter, though I'm afraid I couldn't put a number on it. If you take a small bendable piece of metal like a paperclip and bend it back and forth quickly, you can make it quite hot to the touch; bending metal causes internal friction which releases heat."
] | [
"There are other forms of energy, but ultimately most of it winds up being heat pretty fast. Sound, for example, quickly dampens out and is converted to heat on the surfaces that absorb the energy. Debris thrown from the crash would quickly come to rest, converting their kinetic energy into heat.",
"I will agre... | [
"It will be converted into other forms of energy. Yes, one of those is heat, but one thing the other answers haven't mentioned is things like noise, or vibrations, or changes of state - eg the rubber from tyres may be slightly sublimated during breaking. Think about the sound a car crash makes - it's a considerable... |
[
"What is the largest number of sides a single dice could have before it began to act like a sphere?"
] | [
false
] | null | [
"You need to define what \"acting like a sphere\" means.",
"A coin can only flip over if it bounces, a six sided die already sort of rolls over a hard surface, a twenty sided dice rolls (I don't feel like what they do needs a qualifier). A 100 sided die moves almost like a smooth ball, but it will land on one of ... | [
"In my opinion, we should take the definition from physics. \"Acting like a sphere\" should mean that during a roll the point of contact changes at each point in time. I presume that the actual number of sides is in this case is infinity, but since I'm sure OP wants an actual number I would say that OP's question i... | [
"Well technically a sphere in the real world is not a mathematical sphere either. It is flipping over very small surfaces"
] |
[
"How does the skin on your finger heal so that your fingerprint doesn't change?"
] | [
false
] | A few weeks ago I cut my index finger while slicing some vegetables. After the cut healed, I saw that there wasn't any visible change to my fingerprint. The cut seemed pretty deep so I was surprised by this, hence me asking the question here. | [
"Because fingerprints arise in a layer below The epidermis(topmost layer of skin), the dermo-epidermal junction because of the ridges formed in the dermis. So, as long as the burns are superficial, only the epidermis is damaged while the ridges remain intact and hence the exact same print forms on your epidermis. B... | [
"Because fingerprints arise in a layer below The epidermis(topmost layer of skin), the dermo-epidermal junction because of the ridges formed in the dermis. So, as long as the burns are superficial, only the epidermis is damaged while the ridges remain intact and hence the exact same print forms on your epidermis. B... | [
"DNA is certainly part of any answer about how healing works, but I think OP was particularly interested in how a fingerprint heals to the same design. Given that identical twins, with identical DNA, have different fingerprints, that complicates the answer a bit. Or am I missing the obvious?"
] |
[
"Does the start of the Industrial Revolution mark the first time humans were able to have a global impact on the environment - such as through climate change? Did this happen before the era too?"
] | [
false
] | null | [
"No, the Industrial Revolution isn't the first time we've had an impact, although our most significant impact has been since that period. Before then, human impacts were mostly limited to clearing forests and the occasional extinctions.",
"Human impacts on the planet became significant during the Holocene Epoch, ... | [
"There is evidence that the advent of agriculture and the domestication of animals about 10,000 years ago caused a spike in methane levels (cows produce a lot of methane) that caused a small global temperature rise. Not on the scale we observed during the 20th century up to the mid '90's, but still significant. "
... | [
"I think that the Agricultural Revolution was the first time humans impacted their world directly and negatively. We were able expand populations and form permanent cities thereby changing the earth itself. See the boom Ishmael by Daniel Quinn for the details. "
] |
[
"What can i add to water or saline solution to increase (or decrease) its viscosity?"
] | [
false
] | [deleted] | [
"Mixing water with any miscible fluid with a higher/lower viscosity will yield a mixture with a higher/lower viscosity (and the Refutas equation can be used to estimate the viscosity of the blend).",
"For instance, you could mix ethanol with water, and get a fluid with lower viscosity than pure water. Conversely... | [
"When I was working in a prescription compounding lab we used sodium carboxymethylcellulose because it was cheap, non-toxic, and hypoallergenic. Stuff works well, but it takes a while to incorporate unless you sift it in fairly slowly. "
] | [
"The wikipedia page for ",
"thickening agents",
" gives a pretty exhaustive list of stuff that can make a solution more viscous, including plenty of things you could get your hands on. Most of these things are solids or oils.",
"You can thin a water solution by mixing in a solvent with a lower viscosity as "... |
[
"How does a scent occupy space? Example: in cigarette smoke, is the smell of the smoke bound up in the smoke itself? Can you only smell it as long as you are in proximity to some trace of the smoke?"
] | [
false
] | null | [
"Wikipedia has methane as an ",
"odourless gas",
". I think it's the sulphides that produce the smell."
] | [
"This comment has been overwritten by an open source script to protect this user's privacy. It was created to help protect users from doxing, stalking, and harassment. ",
"If you would also like to protect yourself, add the Chrome extension ",
"TamperMonkey",
", or the Firefox extension ",
"GreaseMonkey",
... | [
"Yep. The same chemical that gives richness to your farts is also the added scent in natural gas."
] |
[
"How stable is the current configuration of sub-atomic matter in the universe? Is it possible for another arrangement to spontaneously occur?"
] | [
false
] | I remember reading an analogy years ago in Michio Kaku's book, "Hyperspace". I'm sure it's a huge shortfall of what's really going on, but it went something like this: Think of the Big Bang like the tension of a fitted sheet over a mattress when one corner pops off. The sheet ripples and relaxes into an organization ... | [
"I believe you're thinking of a ",
"False Vacuum",
"?"
] | [
"That sounds remarkably like what I read about IIRC."
] | [
"In the standard model the configurations of sub-atomic matter are determined once the masses, charges, coupling constants, etc are put in by hand. The standard model does not have any mechanism shifting these constants suddenly or over time.",
"The analogy you describe with the bed sheet is something that could... |
[
"Does engaging multiple senses help ingest more information, and to what extent?"
] | [
false
] | When I’m watching a music video, am I actually taking in visual and auditory information simultaneously, or just rapidly switching? Does it matter functionally? Can using multiple senses meaningfully increase one’s “input bandwidth”? Does engaging multiple senses help accelerate learning? | [
"There's a decent amount of controversy over whether the \"learning styles\" exist. ",
"https://anatomypubs.onlinelibrary.wiley.com/doi/abs/10.1002/ase.1777"
] | [
"Here's a study entitled ",
"\"The Benefits of Multisensory Learning\". <pdf warning>",
" by Shams and Seitz from 2008. I haven't read it and this isn't my area, but they argue that because \"our experience in the world involves constant multi-sensory stimulation\" ... \" it is likely that the human brain has e... | [
"Somewhat, and it can depend on the person. People tend to have different senses that “stick” better—in education you’ll hear terms a lot like “visual learner” or “tactile learner”. These refer to the primary sense that helps a person engage with and recall material. People can take in several senses simultaneously... |
[
"Solubility"
] | [
false
] | How can I determine the solubility of a clear liquid in water? More specifically, I'd like to know how much polyurethane thinner I can mix with water without the solution separating. Given that it is clear how can I tell when it is not possible to mix with water any further. Sorry if I am unclear, english is not my fir... | [
"Unless the liquids are engineered to have identical appearances, they likely do not have the same index of refraction. If this is the case, they should form a visible meniscus when not mixing. If this is not observable to the naked eye, try sticking an opaque rod into the container and measuring its refraction (or... | [
"If you cannot determine it from textbooks or online, you can try mixing them together in a clear glass while adding the polyurethane in given amounts and looking for a separation. You would be able to see a change in the index of refraction once the solutions separate. "
] | [
"You can try to use an indicator like a food dye. You need something that will dissolve well in one solution and not the other, but since I don't know what the base of the polyurethane thinner is I cannot give a specific recommendation.",
"If you have any food dyes lying around you can do a quick test. Put a dr... |
[
"Is there any science to the concept of 'Race' considering our current knowledge of genetics?"
] | [
false
] | I have been seeing frequent references to race. Is it scientific in anyway to reference to race or is it just socio-political bullshit? | [
"Once you start paying attention to genetics, any racial categories you might construct will have absolutely no relationship to the racial categories everyone is familiar with. Most of the 'races' you'd construct will be in Africa, all made up of people that would commonly be called 'black' in the US or Canada. ",... | [
"\"Races\" are generally socio-political. There is no genetic marker that defines your race. Color of your skin, shape of your bones, thickness of your hair, sure, but that isn't enough for someone to determine your race by. "
] | [
"Color of your skin, shape of your bones, thickness of your hair, sure, but that isn't enough for someone to determine your race by. ",
"But isn't that all that race is? A few unimportant physical characteristics?",
"Since race is defined entirely by things like skin color and hair and such, race is an entirely... |
[
"Current thinking on gravity: Is it still considered one of the fundamental forces (with weak, strong and electromagnetic); or is it caused by space being warped by mass and not a force in the way the others are"
] | [
false
] | Just trying to understand old posts | [
"No, no gravity is nothing like entropy. Gravity is typically viewed as one of the four fundamental forces, along with strong, weak, and EM. ",
"Does gravity have its own particle? Maybe. There is a theoretical model in which there is a particle known as the ",
"graviton",
" but it hasn't been directly observ... | [
"Thank you for the reply"
] | [
"The question I have is does gravity have a force carrier like the electromagnetic or weak force or is it an effect of other forces like entropy?"
] |
[
"If 2 used batteries are used with 2 new ones in a flashlight, will the older ones last longer or the new ones drain faster?"
] | [
false
] | To clarify: the older ones are not dead, but on their way. | [
"If the batteries are wired in series, the flashlight will die or at least become very weak once the used batteries are depleted. At this point, the still-good batteries will begin to reverse-polarity charge the dead ones (while the flashlight is on) and this is can lead to the dead cells leaking corrosive electrol... | [
"In parallel, the new ones will charge the old ones. They will eventually equalize."
] | [
"Or they get damaged or explode before they reach that point because they are charged with a high current. Not a good idea."
] |
[
"When I shine a light through fabric, some light gets through. Are the rays coming in a straight line (i.e. there are that many gaps in the fabric) or can the rays \"bounce\" around before getting to me?"
] | [
false
] | [deleted] | [
"Both... the gaps in the fabric are likely bigger than a couple hundred nanometers. This means, to the light, the holes are free space. Near the edges of the gaps, there will be some slight bending of the light, as the very slight motion of electrons in the fabric shift slightly to balance the field of the incident... | [
"Yeah. If the gaps are big versus the size of the wavelength of the wave, the wave won't see it. If a feature is big relative to a wavelength, then the feature can effectively block the wave. I chose hundreds of nm because it's transparent, and the wavelength for visible is between 400 and 800 nm."
] | [
"Both... the gaps in the fabric are likely bigger than a couple hundred nanometers.",
"Do you mention this number because it's the wavelength of ",
" light?"
] |
[
"Gravity question that stumped my grandpa..."
] | [
false
] | Alright, so imagine that earth had no atmosphere and was a perfect vacuum, or at least enough of a vacuum that atoms provided no noticeable friction. If you drop something from high enough, it will eventually stop accelerating and reach terminal velocity until it hits the ground. Well say you are high up enough that ... | [
"The only reason items have a terminal velocity is that their acceleration due to gravity is balanced by their deceleration due to the air resistance they feel. No air, no resistance, no terminal velocity. So the bullet would continuously accelerate till it hit the ground."
] | [
"Terminal velocity is a property of objects falling in a gravitational field through an atmosphere. It is the point at which the acceleration due to gravity is matched by the friction of the atmosphere on the object.",
"Removing the atmosphere removes the terminal velocity."
] | [
"Ok thanks. So if it was shot in an atmosphere, given enough height, it would eventually decelerate to the terminal velocity, right?"
] |
[
"Why is spooky action at a distance not just two photons getting synced up then moving one apart?"
] | [
false
] | I just read an article that says they've confirmed it's at least 10,000 times faster than light. It would seem to me this would be analogous to having two boxes, putting 5 coins in each box, taking one box 15Km away and opening them at the same time and saying they sent data faster than the speed of light. What part am... | [
"I just thought up this analogy, so thoughts would be appreciated.",
"Imagine like you say that you have 2 boxes, these boxes represent particles. In each of these boxes you have 10 magnets, 10 magnets point up and 10 point down (these represent the particle's Wavefunction). You don't know how many of each are in... | [
"I was about to type up the same answer when I noticed yours. Just to highlight the key point (using the example of electron spin):",
"It is not possible to create a classical input state for which this will be true, without having non-local action."
] | [
"I was about to type up the same answer when I noticed yours. Just to highlight the key point (using the example of electron spin):",
"It is not possible to create a classical input state for which this will be true, without having non-local action."
] |
[
"Why is it so hard on this satellite simulator to create a stable orbit around the moon? Is it a flaw of the simulator or does it actually reflect reality? [Java Applet]"
] | [
false
] | null | [
"Technically, all the planets are satellites (of the sun), so their moons are natural satellites of satellites.",
"In theory, the moons in the solar system could, themselves, have satellites. But indeed, due to the relatively small distances involved, and the tidal forces at work, such satellites would not remain... | [
"Here is a good answer",
".",
"Although I suspect the simulator is just flawed - the orbit decay referred to would take just a little longer than the month-or-two that it takes things to collapse in the simulator."
] | [
"Not even remotely. Given that there aren't any ",
" it's impossible to offer a solid critique, but just at a glance one can see that the scale is off by a factor of about fifteen, and the Earth-moon barycentre is in the wrong place."
] |
[
"Are the adductor and abductor hallucis muscles in the foot \"backward\"?"
] | [
false
] | [deleted] | [
"This",
" shows the adductor on the lateral side, from what I can tell.",
"Edit: oops, mixed up lateral and medial. Hard for me to notice at first glance without the rest of the body shown!"
] | [
"That was the page I'd been looking at, but I thought that adduction was defined as movement toward the midline, so I don't understand how a muscle on the lateral part of a structure does that."
] | [
"Ah, apparently in this case adduction means movement towards the midline ",
". ",
"The adductor hallucis muscle [...] adducts the big toe, moving it closer to the smaller toes."
] |
[
"Is this Rainbow Plane in Google Earth a result of the Doppler effect?"
] | [
false
] | Found this in Google Earth while tracing my drive on the 101 (coordinates on image). Why is the effect observed in the satellite imagery? Does it have anything to do with the varying speed of different colored light being captured during the exposure time? Additionally, why does the foremost outline of the plane appea... | [
"It has nothing to do with the Doppler effect. ",
"It seems that this particular camera takes the colour image by first taking a picture with a blue filter, then a picture with a green filter, then a picture with a red filter, and then puts them together. However, the plane moved during the taking of these 3 pict... | [
"not sure but my hypothesis would be that there are four images.",
"The black and white image is used to get absolute light level and then the other 3 are used to split the absolute intensity into 3 parts.",
"EDIT: it might also be used to align the other 3\nEDIT2: it actually looks like the black and white ima... | [
"Actually the airplane makes up the minority of the image so the alignment would be of the landscape in the background. You could align to the airplane but then the landscape would be messed up.",
"Why might there need to be an alignment of a landscape that isn't moving? Well look how far the airplane moved betwe... |
[
"Hummingbirds flap their wings around 70 times per second during normal flight...what is the fastest natural movement that humans are capable of, either voluntary or involuntary?"
] | [
false
] | [deleted] | [
"The National Science foundation released an article on the fastest articulated motion a human can execute, which is throwing. When an arm is cocked back it can store a lot of energy which is then released during a throw. The finger tips can reach over 100mph. A hummingbird flapping at 70 times per second with wing... | [
"Some other apes throw stuff, but it's usually as a defense mechanism rather than hunting. And none can throw things anywhere even close to as accurately as a human can.",
"So if you're tired of hearing that animal X can do Y better than a human: that's our big physical talent. We can throw things ",
" well."
] | [
"I never though about it, but throwing objects (rocks, spears, etc) as a method of hunting does seem uniquely human. I know some primates use basic tools like sticks to get ants out of an ant hill, but do we know of any other animals that hurl objects to hunt?"
] |
[
"Do tools like luminosity.com, dual-n-back, and Brain Age have a significant impact on cognitive ability?"
] | [
false
] | . | [
"The New York Times has an excellent article on this: ",
"\"Can You Make Yourself Smarter?\"",
" They conclude that the evidence is inconclusive. Some studies have shown an increase in fluid intelligence from the tasks in question while others have not. There does not appear to be an academic consensus in eithe... | [
"I'm writing my undergraduate psychology thesis/literature review on this subject. There's so much going on at the moment it's hard to tell. What DOES seem to be the case is that when conducted under optimal experimental conditions (multiple pre/post test assessments measuring composite ability scores, use of activ... | [
"Short answer: Not really",
"Long answer: I think you're confusing \"memory\" as a single component structure. What you are asking is more along the lines of success encoding and retrieving over extended periods of time. Working memory, however, is not that. Working memory relies on higher level cognition and att... |
[
"What would happen if you blew a bubble in space?"
] | [
false
] | I'm talking about a soap bubble... Would it pop, how would it float etc... | [
"Inside or outside your spacecraft? ",
"Inside would be pretty ordinary, though you can blow a bubble into a sphere of water, even without soap, like so: ",
"http://www.youtube.com/watch?v=cXsvy2tBJlU",
" they're using a wire ring to hold the glob of water to keep it from floating away.",
"Outside, your soa... | [
"Because the pressure in space is below water's vapor pressure at it's freezing point. When water boils, it carries with it the enthalpy of vaporization, reducing the temperature of the remaining liquid. This will continue until the temperature is low enough that the vapor pressure equals ambient pressure. Space h... | [
"Because the pressure in space is below water's vapor pressure at it's freezing point. When water boils, it carries with it the enthalpy of vaporization, reducing the temperature of the remaining liquid. This will continue until the temperature is low enough that the vapor pressure equals ambient pressure. Space h... |
[
"What chemically happens in the brain when a person is depressed?"
] | [
false
] | null | [
"Finishing up a Neuro degree here. (Just a bachelor's so if this comment is total crap I'm sorry!) I recently read some relatively new research on how depression affects the brain. Here are some links!",
"https://www.hindawi.com/journals/np/2016/8056370/",
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4819286/"... | [
"I think kaosatang gave a good introduction to the pathophysiology of depression by explaining the morphological alterations that occur to the neurons. However I want to emphasize the changes that promote shift in the neurochemical homeostasis, regarding the question.",
"There is one hypothesis when it comes to d... | [
"There are already places that do ketamine treatments for depression in the US. You basically sit in a Dr.'s office, they give you a dose of ketamine intravenously. You hallucinate for 30 or so minutes and once it wears off you leave the office. Apparently it's pretty effective as far as treating depression for som... |
[
"Why is it that digital displays shake more than the rest of your perception when using an electric toothbrush?"
] | [
false
] | Really, it doesn't matter if it's an electric toothbruth or a head massager or what have you; something that makes the head vibrate. When I look at my computer screen and my digital clock, they seem to shake a lot more than the rest of the world. | [
"It's because those displays are not constantly on, but refreshes at a rate that create the illusion of persistent image. When the vibration is close to the frame rate, it will start interfering with the illusion."
] | [
"Huh, very interesting. Many thanks."
] | [
"Thank you for asking that. I've wondered about this for years...."
] |
[
"Is it possible that all of our scientific theory's could only affect the surroundings we can see? That being earth, our solar system to the farthest we can see in space."
] | [
false
] | How do we know our theory's are even remotely universal. It has bugged me for a long time that people say that gravity, matter and science In general is all universal; the science we have 'created' is definite. But how do we know? A million galaxy's away couldn't there be a part of space where physics don't apply? Wher... | [
"We test our scientific theories on distant things as well as on nearby things in laboratories. ",
"We can see objects that are billions of light years away, and we can see that quantum mechanics and relativity work the same way over there that they do over here. For example, we can see, in both the near and dist... | [
"There's a thing called Noether's theorem, which states, that for every symmetry there's a 'Noether charge' which is conserved. For translational symmetry (i.e. physical laws are invariant under change of position) there's momentum that's conserved which, as far as we know, is true. Even more, quantum field theorie... | [
"So by that then it would be near impossible to have something that defies our scientific theory's? The universe is vast and i just find it hard to believe that there isn't something out there that defies everything we've come to believe. But if you science gurus think otherwise who am i to argue :)"
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.