title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"If we were hunter-gatherers for 99.9% of our existence, why do we get homesick?"
] | [
false
] | null | [
"Homesickness isn't about geography. It is a longing to return to a familiar setting, to reunite with people you have been away from and return to a comfortable routine.",
"This is completely possible in a nomadic society...in fact, it is probably important in an evolutionary sense. A hunting party might be out... | [
"I think you're being unduly harsh. Homesickness as a behaviour is studied and quantified: ",
"http://en.wikipedia.org/wiki/Homesickness",
"Also, the need for a single location as a home is seen across plenty of animal species.",
"I'd say the best scientifically-oriented description of homesickness is as part... | [
"I think you're being unduly harsh. Homesickness as a behaviour is studied and quantified: ",
"http://en.wikipedia.org/wiki/Homesickness",
"Also, the need for a single location as a home is seen across plenty of animal species.",
"I'd say the best scientifically-oriented description of homesickness is as part... |
[
"Have we ever witnessed an object move from the \"observable universe\" to the \"non-observable universe\"?"
] | [
false
] | [deleted] | [
"You may be interested in ",
"this paper",
" which discusses misconceptions surrounding some of the issues you're asking about. ",
"Firstly, you are incorrect that we cannot observe galaxies that recede at faster than c. We can, and in current cosmological models, most of the observable universe (anything wit... | [
"tl;dr: No, by definition.",
"The \"observable universe\" consists of all portion of the universe where the light from those parts has had sufficient time to reach Earth. In order to travel from the observable universe to the \"unobservable universe\", the object would need to travel faster than the speed of lig... | [
"Imagine an object which was some ",
" time ago at a distance ",
" from Earth. Now if the distance ",
" is large enough there comes a point at which the expansion of space will make that distance grow faster than the light can cross it.",
"This will result in an object transitioning from the observable to t... |
[
"Is a liquid magnet possible?"
] | [
false
] | All google had for me is ferro fluid, which reacts to magnets, and colognes. Is it possible to have a liquid permanent magnet? How about an electro magnet? | [
"The concept of a 'liquid magnet' is kinda misleading. As you mention, Ferrofluids are as close as you can get to a 'liquid magnet', but all they are is ferromagnetic particles suspended in water.",
"To truly answer the question, you have to look at what a 'magnet' actually is. Simply, a magnet is a material or o... | [
"What about the earths core or the sun?"
] | [
"So, the line has to be drawn between ",
"permanent magnets",
", magnets such as bar magnets and rare earthmagnets, and ",
"electromagnets",
", magnets that are created by electricity passing through a material. The Earth's magnetic field is generated by the core, which acts as a gigantic electromagnet. ",
... |
[
"Is it possible to use RADAR or other waves to find gold?"
] | [
false
] | null | [
"Geologist here.",
"Geologists currently have no remote sensing method that with pick out \"gold be here.\" Indeed, seismic surveys do not directly find oil, but instead are used to used to find oil \"traps.\" These are geologic features such as folds in the rock where oil might congregate. The oil company descri... | [
"The thing with gold is that you seldom find them in very large quantities.",
"Things like coal and oil deposites can be found using using seismic serveys because they are usually massive in scale, hundreds of meters wide and very distinguishable.",
"Gold is not nearly found in such large quantities."
] | [
"Kimberlite pipes are a geologic feature, and are the go to geologic feature for diamonds. The diamonds in Kimberlites are found indirectly as well; meaning that geologists will discover the Kimberlite structure first, then determine its diamond content.",
"Gargantua makes an excellent point that you don't really... |
[
"Are all spiderwebs chemically identical?"
] | [
false
] | Do spiders of different species create different chemicals to use in their webs? | [
"No, not all chemically identical. Yes spiders create different chemical structures for their silk depending on what it is used for. I worked in a laboratory where we studied spider silk. Basically in order to understand the differences in the different types of silk, and between species. We would feed the spiders ... | [
"How happy were you when you saw a thread asking about something that you worked on?"
] | [
"It is somewhat satisfying considering it is a more obscure topic and most people although interested by it don't care about the details"
] |
[
"Why do the activated carbon balls used as dessicant in hard drives repel each other? What makes them electrically repulsive?"
] | [
false
] | Here is I recovered this stuff from a couple of hard drives. I hadn't seen it before. On further research, it seems to be , specifically, , but that doesn't explain the fact that these little beads repel each other (the picture was taken holding the canister totally still, the balls are about 0.5 mm diameter). My daugh... | [
"I am not a scientist but the effect you are observing appears to be static electricity. "
] | [
"yes, I got that. The question is what is the source of charge that is causing the static? What molecules are showing their electronegativity in this way?"
] | [
"The beads are not good conductors, neither is the plastic, electrons get rubbed off into other pellets or the walls, and they hold the charge, like rubbing a balloon on your hair. "
] |
[
"Do domestic pets recognize that they have a name, or do they hear their name and think of it as a command?"
] | [
false
] | What I mean is that if you call your dog, do they know that what you are saying is their name, or do they take it as a command to come, like hearing "sit" commands them to sit. | [
"Could you provide some sources on this?"
] | [
"Could you provide some sources on this?"
] | [
"More specifically, do you have peer-reviewed sources? "
] |
[
"How does 'displacement' work as a means of measuring weight?"
] | [
false
] | I've seen TV dieting shows of obese contestants being weighed in a water tank and mesuring the water they displace from it. I'm reading 'The Hunt for Red October' and the weight of submarines is given as the volume of water they displace. I remember the story of Archimedes running through the town shouting 'Eureka!' be... | [
"As long as the object is floating, the displaced mass of water will be equal to the mass of the object. Hence the reason it's used for ships.",
"When submarines are on the surface, the displacement is equal to their unballasted weight. When they submerge, they take on additional water, increasing their mass such... | [
"The trick is to let it go and see how much water must be displaced for it to float. For the method to work, it must be in equilibrium; this isn't valid for a rock that sinks to the bottom.",
"Archimedes' principle says that the buoyant force keeping the object afloat (and therefore equal to its weight) is equal ... | [
"You do need to know the density."
] |
[
"Are all subatomic particles the same exact size?"
] | [
false
] | null | [
"They come in a whole range of \"sizes\". Elementary particles are treated as pointlike in the Standard Model, so as far as we know, they are.",
"But there are subatomic particles which are not elementary particles, like protons, and nuclei.",
"These are composite particles, and they're not treated as pointlike... | [
"Yes, all quarks are the same size."
] | [
"Yes, all quarks are the same size."
] |
[
"What is the difference between strain, mutation and variants? E.g. D614G vs B1.1.7"
] | [
false
] | null | [
"Strain and variant are likely to be used interchangeably and I don’t think they have a particularly different scientific definition. ",
"Mutation technically refers to the specific change within the virus and where it is. Variant technically could also refer to mutation in another context (ie. a fruit fly with s... | [
"To add, when you see D614G (\"Doug\"), that's giving a specific mutation. In this case, the 614th amino acid in the protein is changed from aspartic acid (abbreviated D) to glycine (abbreviated G). When you see something like B1.1.7, that's referring to the lineage. That works like a family tree, and lets us follo... | [
"No. It depends upon the context that you are writing. ",
"If you are discussing the new covid variants generally, you could use the term variants. If you are discussing a particular variant or strain, you would be able to further define it by its mutation. You could also describe divergence from a particular str... |
[
"What does the \"CBA\" mean in the \"CBA mice\" used in experiments?"
] | [
false
] | I'm a very science-inclined writing tutor at my college. While helping a student with her paper today, I came across this term that I wasn't familiar with. As we do with all acronyms, we recommend that students define them in their writing before they use them as simple acronyms (e.g. say what NASA stands for before yo... | [
"Your close friend is almost correct in saying that most traditional mouse nomenclature is just a name at this point. In reality, the naming was just somewhat arbitrary when mouse breeding first took off.",
"For instance, the most commonly used C57BL/6 and C57BL/10 mouse lines get the 'C57' portion of their name ... | [
"You're correct in that it's genetic in origin. CBA refers to a strain:",
"In 1920, Strong developed the CBA inbred strain from a cross of a Bagg albino female and a DBA male. CBA was selected for a low incidence of mammary tumors.",
"Source 1",
"Source 2"
] | [
"The DBA mouse was originally Dilute Brown Agouti, so CBA is likely a derivative of that. Just adding in what I know to the conversation already underway about the DBA/Bagg crossbreed.",
"Source: I've used DBA mice in research."
] |
[
"Would it be possible to launch a rocket into orbit \"manually?\""
] | [
false
] | [deleted] | [
"The Apollo astronauts were trained to fly the Saturn V if it went somewhere they did not want it to go, so answer \"Yes\". But it is hard, but they trained to do it, and could if needed to."
] | [
"Conceivably, yes. ",
"Gordon Cooper",
" was able to manually calculate his reentry due to a systems failure. "
] | [
"Yes, but it's ",
". Go play with ",
"Orbiter",
" if you don't want to do anything productive for the rest of the night."
] |
[
"Why does sound pressure only decrease with 1/radius from a source instead of 1/r^2 like intensity?"
] | [
false
] | Yes this came up in class, however, nobody can give me a clear answer on this and any reference I come across just assumes that pressure decreases with radius from a source. For example, just tells us that pressure decreases with 1/r. If we assume that pressure and velocity decrease with 1/r then you can see why inten... | [
"Sound is a pressure wave. In other words, the pressure satisfies a wave equation. For isotropic propagation from a source, it will be a spherical wave. The solution for a 3D spherical wave is given ",
"here",
". Note the 1/r dependence the solution has."
] | [
"Unfortunately, I can't think of a way to intuit it. The solution to the wave equation simply ",
" the solution. There's nothing else it can be. ",
"You said in the original question that intensity decreasing as 1/r",
" makes sense to you - just take it to the next step, since intensity is proportional to t... | [
"Intensity is kind of like Power, as you know; it's just power divided by area. Power is how much work is done in so much time, and finally work is a force pushing through a distance. ",
"If we take pressure, which is a force over an area and want to know how much intensity it has, we need to multiply by the di... |
[
"Are different sections of our bodies different temperatures? Everyone talks about internal body temp, but how much variance do we normally see in the temperature in extremities and such?"
] | [
false
] | null | [
"In humans the average internal temperature is 37.0 °C. However, we don't always has exactly the same temperature at every moment of the day. Temperatures cycle up and down, controlled by our circadian rhythm. The lowest temperature occurs about two hours before we normally wake up (Altough the circadian rhytm can ... | [
"It depends on the situation. If it is midly cold outside, it could be almost nothing; if you are in the artic, a lot."
] | [
"Could you use numbers please?"
] |
[
"Do animals get STDs?"
] | [
false
] | [deleted] | [
"Yes, animals can contract STDs the same way humans can and do so all the time.",
"Not just mammals either, even insects, nematodes, arachnides and reptiles are known to catch and transmit STDs. Despite the moral stigma attached to such diseases in many societies, STDs are perfectly indifferent to moral standards... | [
"Yes, ",
"for example the koala",
" a large percentage of them have chlamydia. Another example would be feline Aids caused by FIV. Herpes widely effects the mammal population as well with many different species effected. Most mammals and even birds and insects have some various form of STDs that can effect thei... | [
"Your examples are too vague, making them a little misleading and easy to misinterpret. The most common transmission mode for FIV is believed to be via saliva in bite wounds and perinatal transmission, not sexual transmission. There are also tons of viruses in the Herpesviridae group that are not sexually transmi... |
[
"Can anyone explain to me in simpler terms why objects of different mass accelerate down a sloped plane at different speeds (ex: sledding down a hill)?"
] | [
false
] | null | [
"If the only force acting on it was gravity then it would fall through the slope :P"
] | [
"Very wrong answer. The explanation must involve dissipation, i.e. friction. In an idealized scenario without friction, an analysis of potential/kinetic energy does not work. Both kinetic and gravitational potential energy are proportional to the mass, so mass will cancel out of the calculations!"
] | [
"Well, all things have the same acceleration due to gravity. The effect you're talking about is caused by friction.",
"Large things have proportionally less surface area for drag to operate on. So there is proportionally less drag than smaller objects.",
"A small sled is more affected by impacts with other obje... |
[
"Why don't we use planes that go higher and higher until they reach orbit?"
] | [
false
] | I'm sure that there's a reason why we need rockets, but it seems to me that the superplane idea could save money (if it was possible) Thanks! | [
"Orbital speed at low Earth orbit is around 17,500 mph. The ",
"SR-71 Blackbird",
" still holds the aircraft speed record at 2,193 mph. To do what you're asking would require something like the SR-71, but with rocket engines in addition to air breathing engines, so it makes more sense just to make rockets to go... | [
"Mach 5.4 is 1,838 m/s which is 4,110 mph. All other numbers are correctly in mph."
] | [
"Yes, an airplane could save fuel and therefore money ",
". This is not easy. At around Mach 5 atmospheric drag is very high and it produces very high temperatures (in fact this is the limit of the so called ",
" in which anything moving through the atmosphere burns up like a meteor).",
"However there is ongo... |
[
"(Paleontology) when it comes to the dinosaurs that did have feathers, what was their skin like underneath the feathers?"
] | [
false
] | null | [
"Hi Marco-Catbird thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the f... | [
"How do you flair a post?"
] | [
"I want a biology flair"
] |
[
"What are some good, reasonably simple, experiments I can do with 6th graders to show scientific concepts?"
] | [
false
] | null | [
"Thanks! I'll look at the links and subscribe to ",
"/r/asksciencediscussion"
] | [
"Hi POCKALEELEE thank you for submitting to ",
"/r/Askscience",
".",
" Please add flair to your post. ",
"Your post will be removed permanently if flair is not added within one hour. You can flair this post by replying to this message with your flair choice. It must be an exact match to one of the fol... | [
"Greetings ",
"/u/POCKALEELEE",
",",
"while your question has ample merit, it doesn't really fit within the purview of ",
"/r/askscience",
".",
"The good news, however, is that it quite well suited to our other sub: ",
"/r/asksciencediscussion",
" where broad enquiries and open-ended questions are o... |
[
"What would happen if you explode a hydrogen bomb in a kilometer-thick metal sphere?"
] | [
false
] | For example a 10 megaton hydrogen bomb going off in a kilometer thick lead sphere. Will it amplify the explosion kind of like a ? Or will nothing really happen and the lead sphere would contain the explosion? | [
"Instead of lead, use beryllium. While preventing expansion helps to keep the reaction going, using a neutron reflector has the most impact on yield. Hydrogen bombs have much larger yields due to the boost from the neutron burst of the fusion reaction."
] | [
"100 petaJoules of energy (rougly half a Tsar Bomba), if applied in a uniform fashion should be enough to liquify the entire lead sphere. ",
"Where is your source for that??",
"Heat capacity of lead: 1.44 J / cm",
" / K",
"Formula:",
"heatCap * deltaT * volume = energy",
"1.44 J / cm",
" / K * deltaT ... | [
"I'm not entirely sure what kind of mechanisms they use for dissipation, but nuclear tests were performed underground without disastrous results. On one hand, I'm sure their containment walls were much less than a kilometer of metal. Otoh, they have a lot of dirt around them. AFAIK, the tests didn't result in kilom... |
[
"What are some chemicals that rank 4 - 4 - 4 on the Hazmat Diamond?"
] | [
false
] | null | [
"Carbon monoxide is 4-4-2. (not highly reactive)",
"Trinitrotoluene is 2-4-4. (not highly toxic)",
"I don't know of anything offhand that is 4-4-4, most violently reactive agents aren't also extremely poisonous because they can't persist in the body long enough to cause toxicity.",
"Side note: googling a bunc... | [
"One of my favorite science blogs is In The Pipeline, more specifically the recurring ",
"Things I Won't Work With entries",
". I'm pretty sure there's a substance or two in there that qualify.",
"An example from the entry on ",
"chlorine trifluoride",
":"
] | [
"We're probably already there for being on this subreddit as it is.\nAlso, thank you for your batteries!"
] |
[
"What happens if you eat a rock?"
] | [
false
] | [deleted] | [
"If it's small, you'll probably feel no real effects. It will pass through easily. If it gets stuck in your appendix for years it might form a granuloma or something. If it manages to perforate your appendix then you might be in some trouble.",
"If it's small-ish and smooth, it'll go through your GI tract pretty ... | [
"excellent response. But remember, ",
" If you ",
" ",
", talk to your doctor."
] | [
"You are talking about ",
"gastroliths",
". They can hang out in different parts of the gastrointestinal tract depending on the species. They can serve different functions (mostly grinding of food though). They get polished over time from the grinding (not digested). They can also be ingested accidentally or in... |
[
"Are brown dwarfs solid or gas?"
] | [
false
] | null | [
"The ",
"inner layer of jupiter",
" is theorized to be composed of metallic solid hydrogen which forms when hydrogen is compressed at 3 million atmospheres pressure. At high enough pressure, the hydrogen will begin to fuse, creating a star. In brown dwarves, the pressure is high enough for deuterium, a hydroge... | [
"Brown Dwarfs are essentially high mass gas giants (bigger than Jupiter) which fall just short of the mass necessary to sustain hydrogen fusion and become a star. So they're mostly gas, although there might be a solid core like what Jupiter is believed to have."
] | [
"Something much bigger than Jupiter but too small to be a star."
] |
[
"Why does proximity to a light/heat source matter when dealing with light/dark colors and heat absorption? (Science fair experiment in text)"
] | [
false
] | I recently helped my daughter do a Science Fair experiment to demonstrate which color clothing would keep you cooler on a sunny day, light or dark. We took two digital thermometers and made a pocket of construction paper for each one - one black, one white. We placed the thermometers in their pockets and put them equid... | [
"When a point source radiates, the intensity of the radiation is proportional to the square of the distance between the observation point and the source. It's called the ",
"inverse square law",
". For the first stage the bulbs were about 24 inches away, and the second stage the bulbs were about 5 inches away. ... | [
"Thanks so much! This is really what I was looking for - the three types of heat transfer. May all your posts be upvoted."
] | [
"You should have a 3rd probe sitting behind, lets say a mirror, near the two shirts to provide an ambient temperature baseline.",
"The key to remember that the intensity of the light from a normal incandescent bulb is going to drop off with the inverse of the square of distance to the target. Thus an object at 2... |
[
"I'm an identical twin. What percentage of my DNA is like my brother's, and how likely will one of us develop a disease the other won't?"
] | [
false
] | As the title says, I'm an identical twin (both males); I also know humans and chimps have ~98.8% similar DNA. I'm a bio student with a background in psychology, so I'm familiar with most biological terms. I realize nature and epigentics play a role here so 100% isn't the correct answer, and there won't be a correct ans... | [
"Actually, 100% is more or less the correct answer. Identical twins are both from the exact same egg and sperm, so DNA cannot really be different. Epigenetics definitely does play a role but doesn't actually change the CODE of the DNA. Epigenetics changes expression of genes via processes such as methylation. Most ... | [
"Thanks for your reply! Being a twin I've always read that we're 100% alike, but we're as opposite as can be for many, many traits including stark physical difference. So while I've known it to be 100%, it just felt ",
"."
] | [
"How \"stark\" is this physical difference? Diet, environment and activity all play a major role in determining what an individual looks like. The genome is a \"basic\" plan. To use a fairly shit analogy....your genome is the plan for a house....the environment that house is built in will determine what bricks are ... |
[
"Does Earth experience a tidal force from Sun?"
] | [
false
] | null | [
"Yes, we experience a tidal force from everything, it's just question of magnitude.",
"The tidal force from the Sun is about ",
" 44% as strong as from the Moon",
", because unlike the basic gravitational force, the tidal force drops like 1/r",
"Edit: 44%"
] | [
"You don't even need calculus to show this, since you're not dealing with infinitesimals. Plain old algebra will do:",
"Say you have a moon that's a distance \"r\" away from the center of a planet. The planet itself has a radius of \"r\". The gravitational force scales as 1/r",
" , but the side closer to the pl... | [
"The tidal \"force\" is really the difference between the gravitational forces at two different locations: the Moon pulls on the near side of the Earth harder than it does the center. So if your source if farther away, you lose out 1/r",
" because gravity is weaker, but also an additional 1/r because it's ",
"... |
[
"Is this a theoretically possible way to look back in time?"
] | [
false
] | Okay, assume these two things are true: We have telescopes that can see nearly infinitely clear and far We can send objects into space at a speed faster than 1/2 the speed of light. We send what's basically a telescope attached to a huge screen into space at 0.51 times the speed of light. The telescope is pointed at ea... | [
"I'm confused. This is a way to document life as it is and see it in the future. Though I think normal video cameras are better for that. Why do you think that this would be able to see into the past. The telescope is moving slower than the speed of light, so there is no way it is going to see light that has left b... | [
"I see where you're getting stuck. You're thinking that, after 1 year, the mirror is 0.51 lightyears away, so it will look like the mirror-earth is 1.02 lightyears away. But that's not what it will look like ",
", because while the mirror is in fact that far away we won't see the light that's reflecting off of it... | [
"The mirror can only be sent away from earth at up to the speed of light, and any signal returning from the mirror is also limited to the speed of light. You would never see a reflection in the mirror of a time before the mirror was launched. If we were to find a mirror already in place(or something like a black ... |
[
"Most low level cumulus clouds have a very flat underside, does this mean that the atmosphere has a sudden decrease in air density at this altitude, if so, why?"
] | [
false
] | null | [
"Essentially there is an altitude where water will no longer be a condensed vapour - the 'cloud' keeps going below that plane, but the moisture below is in gaseous state and so is invisible."
] | [
"The level where the bottom of the cloud appears is based on the thermodynamic properties of the atmosphere, and is typically called the Lifted Condensation Level. It often appears flat because the thermodynamic properties of the atmosphere that define the LCL do not often vary significantly over short distances."... | [
"That is actually because the air hits the tropopause and can't pass through it, so it spreads out. The tropopause is the place in the atmosphere where the air starts to warm with increasing height. A parcel of air cannot rise if it is cooler than its environment, which is what happens at the tropopause. In thun... |
[
"Would you feel centrifugal force in the absence of gravity?"
] | [
false
] | null | [
"In physics we have this idea of \"fictitious\" forces. So we know, from Newton's laws, that inertia is a thing; which is to say, an object in motion stays in motion unless acted upon by an outside force. And we also know, from relativity, that being at rest, or being in motion at a constant speed and direction, al... | [
"Yes. Centrifugal force is something you experience because you are being accelerated in a circular path. (It doesn't really have to be circular, but that's when we usually use the term 'centrifugal'.)",
"Example: you sit in a car, the car turns left. You experience it as a \"force\" pushing you towards the right... | [
"Yes you would. There is a breakdown of it in a comment I posted ",
"here"
] |
[
"[Physics] What would happen if a helicopter flew into a region somehow filled with a gas more or less dense than our atmosphere?"
] | [
false
] | Helium is 6 times dense than air, sulfur hexaflouride is 6 times dense than air. Now that we know that they makes Adam sound hilarious/demonic, what would their effect be on something that depends on atmospheric density to operate properly. Our helicopter is a magic helicopter; it will always get enough oxygen to supp... | [
"Well at the moment the helicopter entered the region, part of each blade would experience a sudden difference in forces at the point where it crosses the boundary which would quite possibly tear the blade asunder, or at least cause some major jarring. ",
"Assuming it made it through the transition through yet mo... | [
"Sudden increase in effort needed by the rotor engine to maintain the same speed. If it helps, imagine going 10mph in a car, and changing from 1st to 5th, and it would give the same effect, i.e. the engine would struggle to the point of stalling, if something didn't shear, that is."
] | [
"Intuitively I thought that the helicopter would function better in the sulfur hexafluoride because of the increased density of the air. What would cause the stall?"
] |
[
"What's the deal with additional spatial dimensions?"
] | [
false
] | [deleted] | [
"Actually this picture of the universe is already ruled out by experiments. We now know that the universe is very very flat, which means that it is infinite and unbounded.",
"Every particle has a certain number of degrees of freedom that's dependent on the number of spatial dimensions you have: you can move in th... | [
"We now know that the universe is very very flat, which means that it is infinite and unbounded.",
"No. We only know that it is either infinite or very big (at least several times the volume of the observable Universe). But we can't rule out the possibility that it is finite and very very large, we can only put c... | [
"Oh, yes, true of course. :)"
] |
[
"How does rain effect cigarette smoke/the diffusion of odours?"
] | [
false
] | I have just moved in opposite a flat full of very ignorant students. They smoke out of their kitchen window from about mid-day till 3-4am, which means if I have my windows open at any time that they are awake the smell of the smoke travels across the street (which is very narrow) and into my flat. Today has been very r... | [
"The rain actually has a cleaning effect on the air. When rain falls, it attracts many aerosol particles including the particles made by cigarettes which cause their smell. Then the particles get brought to the ground and are released into the ground, never to reach your nose."
] | [
"You sure about that? First off it’s water vapor, not steam (or you’d be cooked). Second off, it’s my understanding that warm damp environments make your nose more sensitive, along with reducing congestion."
] | [
"Yes, same reason a shower fart reaches your nose faster. Steam particles rise."
] |
[
"If second and third generation particles can decay, how can they be fundamental?"
] | [
false
] | null | [
"Fundamental-ness has nothing to do with decays - it merely requires the particle not to be made up of other particles. Does the fact that a photon can pair-produce particle/antiparticle pairs make it non-fundamental?"
] | [
"That's just it though. It isn't more fundamental \"constituents\". Putting a mu neutrino with an antineutrino and an electron doesn't give you a muon in the way that two ups and a down quark give you a proton. A muon is a muon, and the particles that are expelled from its decay aren't sitting packaged together, b... | [
"Thanks, so it isn't that a sencond generation particle is made from first generation particles; it can just decay into them. ",
"Is a second generation particle less stable than a first generation particle due to entropy? "
] |
[
"Will supersymmetry stand up to LHC data? If not, are there any good alternate theories?"
] | [
false
] | While catching up on my podcasts last week, I heard something on the 3 March Nature podcast in a very brief discussion about the data coming off the LHC. The guy being interviewed (Mark Peplow) says that the lack of the discovery of supersymmetrical particles is: one in the eye for supersymmetry theory basically. They ... | [
"Mark Peplow is full of crap, and I will tell you why. I'm going to ",
" lead you through how theories in particle physics phenomenology (a.k.a not string theory) work, with a special focus on the idea of a parameter space. Then I'll ",
" talk about the parameter space in a particular supersymmetric theory, a... | [
"1) Definitely premature. The LHC has only gotten up to about 50% power and it hasn't even begun to do what it was designed to do: find the Higgs boson. It produces mountains of data which takes armies of grad students years to analyse. If supesymmetry is produced, it might take years to find. It's also possible th... | [
"Loved this. thanks a lot for posting. I don't really know much about SUSY aside from the fact we worked through that weird fermion-boson relationship in grad quantum mechanics."
] |
[
"Does alcohol-containing antiseptic cause skin cancer?"
] | [
false
] | Since alcohol (usually ethanol) causes dozen types of cancer in the human body, does disinfecting your hands frequently cause skin cancer? | [
"There is little evidence to suggest that alcohol itself causes cancer. For instance, the claim that alcohol-containing mouthwash use can \"cause\" oral cancer is questionable [1]. However, when ethanol is metabolized in high concentrations, high levels of reactive oxygen species (ROS) that can have genotoxic eff... | [
"This",
" source concludes that the risk from dermal exposure is \"negligable\" again due to lack of significant systemic absorption that is thought to be linked with colorectal/breast cancer. Some cancers (e.g. throat) may be due to local effects but it was suggested this is through alteration of cell membranes ... | [
"I'll agree with these comments. The carcinogenic effects of alcohol inside the body are due to its metabolism and the cellular reactions of the organs (like inflammation). I would not expect topical use of alcohol on the outer layer of skin or on wounds to have any measurable effect on cancer initiation or progr... |
[
"Does the incline of a treadmill increase the amount of calories burnt (theoretically)?"
] | [
false
] | I have searched for the answer but I couldn’t find any scientific answer to this, namely any mathematical proof. I know that when you run uphill, you gain potential energy because of the change in the altitude. You are doing work against the gravity. But with the inclined treadmill you don’t change the altitude and the... | [
"Biomechanically speaking, you’re lifting your legs up higher to step up on the incline. This creates more work in your leg muscles, which means your heart needs to beat faster to keep up. This burns marginally more calories depending on how high the incline is.",
"ETA “marginal” because if it’s a 1.0 incline it’... | [
"You are still gaining that gravitational potential energy with each step - it’s just that the treadmill brings you back down to the ground level at the end of each step. So you still need to expend that energy as if you were running up a hill. ",
"It’s the same idea as taking the stairs up to a top floor and the... | [
"Imagine you step up a hill sideways while wearing roller skates. You are expending more energy than stepping sideways on flat ground, yes?",
"Then after stepping up the hill you roll backwards on your skates back down the hill.",
"The rolling part doesn't change your expenditure of energy right?",
"I think t... |
[
"Can someone break down the science behind why pyrex can't be used to make crack?"
] | [
false
] | null | [
"Pyrex brand glassware changed from borosilicate glass to soda-lime glass, which is also known as flint glass. ",
"Because of the temperature generated in the reaction (acid-base) a lot of heat is generated, flint glass can't handle the rapid temperature change because it expands too much near the heat, causing ... | [
"So is this one of the reasons that vintage pyrex is so expensive on ebay? "
] | [
"relevent"
] |
[
"What is it that allows some (usually autistic) people to remember ridiculous amounts of information perfectly? Is this something we could all, over time, learn/evolve to have?"
] | [
false
] | null | [
"Scientific American recently had an ",
"article",
" discussing the value of forgetting. The flip-side of the ability to remember everything was an inability to ",
" anything. This makes it hard to differentiate between important things and dross or to extract meaning from that flood of raw information.",
"... | [
"Exactly what I was going to say. Great memory in these instances comes at a cost. ",
"However, it is possible for the average person to remember a ",
" more than you would think. You just have to spend time and effort learning how to do it. For instance, in ancient Greece people would memorize the entire I... | [
"\"The Boy with the Incredible Brain\" A must watch if you haven't seen it.",
"http://video.google.com/videoplay?docid=4913196365903075662"
] |
[
"My GF won't wash fruits or vegetables before eating them. I think she's gambling with our health; she thinks I'm paranoid. Who's right?"
] | [
false
] | This morning she cut up strawberries and dropped them on her cereal without washing them. All I could think about was the trace bits of dead bugs, pesticides and fertilizer she must be eating... Edit: Wow. This sure struck a lot of interest. Thanks for the input! | [
"As someone who worked in produce for four years while slaving through college, wash everything you buy because stuff happens to it that you don't want to know about.",
"As someone who did food microbiology research for a few years, washing it with water won't get rid of things like bacteria and pesticides anyway... | [
"I saw an employee at a supermarket spray a pallet of tomatoes with Raid. Folks who harvest vegetables in my town do some unsanitary stuff while they're at work. They also leave their break areas looking like a rubbish dump. ",
"I used to buy a ",
" of tomatoes for my restaurant, and I had to get cleaner for th... | [
"I saw an employee at a supermarket spray a pallet of tomatoes with Raid. Folks who harvest vegetables in my town do some unsanitary stuff while they're at work. They also leave their break areas looking like a rubbish dump. ",
"I used to buy a ",
" of tomatoes for my restaurant, and I had to get cleaner for th... |
[
"Why is the gender gap in life expectancy so low for some countries and so high for others?"
] | [
false
] | I was looking at the life expectancy for different countries for fun and noticed the gender gap differed quite a lot and doesn’t even seem consistent across similar countries. (This is all 2018 data) Nigeria has the smallest gap I could find: 1 year. Men and women live a pretty similar length there. But other high pove... | [
"Places with high rates of violence tend to have similar lifespans for men and women. When people are dying due to age/disease, that usually results in women having longer lifespans, as they have some physiology which offers protective benefits for certain diseases, leading to slightly longer lifespans on average ... | [
"Being a male infant is more often deadly for several reasons and can bring down life expectancies due to more cases of infant mortality being males. But female mortality related to childbirth can bring ages on women down significantly as well. So really depends on which way statistics are skewing and how infant mo... | [
"Gender gap often relates to jobs people do so a large army that engages in fights with high casualty rates lowers male life expectancy, jobs like mining will result in lung diseases which lower life expectancy etc."
] |
[
"What's going on inside an object which rotates about 2 axes?"
] | [
false
] | Through high-school, I learned that an object's inertial movement is the sum of a fixed velocity through space, and a fixed rotation about one axis. A while back, I noticed that when you spin up a pen by shearing your palms against it quickly, it will often end up rotating about 2 axes, one axis being from tip to tip, ... | [
"Be careful with the language here: the pen is really only rotating along one axis at any given time, it's just that, as 33a mentions, that axis moves."
] | [
"If I remember correctly, the reason that your pencil will rotate about 2 axes is that its moment of inertia is different depending on which way it is spinning. For this reason, a perfect sphere will only rotate about 1 axis.",
"However, the Earth is not a perfect sphere, and is slightly wider at its equator. T... | [
"The rotation of any object in three dimensions with constant angular momentum will trace out a 2D torus in the space of all rotations. So if you start a pencil rotating along some initial arbitrary axis, it will appear to wobble from side-to-side as its rotational trajectory moves along the torus.",
"There is a... |
[
"Can you have \"extra\" or \"supplemental\" mitochondria?"
] | [
false
] | What would happen if you tried to give someone "extra" mitochondria? For example, if they could be grown in a petri dish and injected into a human. This question was motivated by a brown fat discussion. | [
"Given that mitochondria are large organelles that are found within all our cells, it' impossible to supplement them, they must develop and divide within the cell. However, one way you could increase the number of mitochondria in your cells is through exercise, especially aerobic exercise. This is because aerobic ... | [
"Thank you. This was very informative. I apparently completely forgot how cells work."
] | [
"One of the most interesting things about Mitochondria is that they carry ",
"their own DNA",
", which is effectively only passed down from the mother. I conjecture that if some way was found to grow genetically engineered ",
" mitochondria and get them into someone's cells, it could be a therapy for certain ... |
[
"How fast do antibiotics start working?"
] | [
false
] | I had a discussion with a friend about this recently and we couldn't figure out how fast they really kick in. | [
"It depends on the type of antibiotic, and the type of \"bug\" it is aimed at stopping. Also, it depends on where the infection is- bacteria that infect a heart valve, for example, take much longer to get rid of than, say, bacteria that infect other places. ",
"Some of them actually kill bacteria, while others j... | [
" medications take five \"half-lives\" to reach steady state, which means a constant level in your body making it the most effective. Often this is when they start being most effective. Medications are generally dosed on their half lives, especially older ones like amoxicillin which don't have much post-antibiotic ... | [
"The answer to this question also is the same. It depends. "
] |
[
"Why does eczema show up in different places on different people?"
] | [
false
] | So I've had mild-moderate eczema all of my life which affects the insides of my elbows and knees, and the front of my neck. I know a lot of people get it on their hands, and some unlucky people can get it on their eyelids. What is it that determines where you're affected by eczema? | [
"Eczema is usually a physical symptom of a larger underlying inflammation going on inside the body. It is very VERY useful to be aware of the foods your eating and to change what you are consuming.",
"The typical American diet is in absolutely zero way helpful to the reduction of inflation in the body. "
] | [
"I have something similar, namely a form of psoriasis that dries and cracks my skin. I actually developed it on my toes. It then spread to my knees and elbows, but after treating it with turmeric, it moved onto my fingers and has stayed there ever since. It will slowly move between fingers indiscriminately. It does... | [
"I had this many years ago. One time on a hunch I bought some expensive soap from Sephora and it went away. $35 a bar of soap.",
"These days I buy the $5 organic soaps from Whole Foods or some other organic store. Some are almost as good as the $35 soap and some I avoid.",
"I think it’s an allergy or some other... |
[
"Relativity Question"
] | [
false
] | So I got two notions in high school science class which may or may not be correct: My question is - if 1 is true, then how is it determined in #2 for whom time runs slower, because isn't it also true that the earth is speeding away from the spaceship at near light speed, and then returning (relatively speaking), so mor... | [
"Relativity is a tricky subject to introduce, because it relies on a lot of basic concepts that are new to most students. Too often, it's just attacked as \"Here's some algebra,\" which doesn't really get the job done, in my opinion.",
"The first basic concept is of an ",
" An event is a point in spacetime. A "... | [
"1) True",
"2) True",
"This is called the Twin Paradox. The key is that ",
" reference frames are equivalent, so when the spaceship stops, turns around, and comes back, it breaks the symmetry."
] | [
"Possibly one of the best succinct explanations I've seen. Nicely done."
] |
[
"How exactly does light hitting a material create heat?"
] | [
false
] | Ok, so I have a pretty good grasp of the modes of heating (in this case radiation) and the general physics of light being absorbed and exciting electrons. However, I started thinking about a single photon and single atom. My understanding is that as the light comes into contact with a material, if the material absorbs ... | [
"Don't overthink the quantum mechanics of it. When photons bombard a material, they collide and thus impart momentum - and so kinetic energy - to the material. ",
"There is of course more detail, but the QM complications do not override the physics of collisions. Chucking marbles into bowling balls will move t... | [
"What I love about this explanation is how quantum mechanics makes everything goofy... except conservation of momentum. ",
"I met Frank Wilczek once, who the Nobel Prize for showing that momentum is conserved in destructive particle collisions, thus providing a framework for all particle accelerator detectors now... | [
"Yes. When you step back and think of the final and initial states only, there is a huge simplification - the theory of collisions prevails.",
"This is also done in mission planning, or otherwise the calculation of orbits for small bodies. If a space vessel swoops past a planet for a little gravity assist, or f... |
[
"Rotating water bottle in a freezer?"
] | [
false
] | So if you fill a water water 1/4 or 1/2 full and put it on it's side it'll freeze on that side, obviously. What if you fill it the same amount, put it on it's side, and put that on a rotating mechanism (rotating on its side), how would it end up freezing? Would it just freeze all over around the edges? Or what?! | [
"It would form an annulus of ice. The thin film of water on the upper part of the bottle will freeze easily, and then will slowly grow until all the liquid water is consumed."
] | [
"Make an hypothesis, then do the experiment and report back!"
] | [
"I can't think of a reason why it wouldn't freeze evenly around the sides of the container. Not that I'm an expert on water freezing, but it's a well-educated guess. "
] |
[
"If we can tame foxes across several generations by artificial selection, why hasn't anyone experimented with artificially selecting for intelligence?"
] | [
false
] | null | [
"Many species of animal, for example, the dog have been bred to be more easily trained. For example, the Collie breed of dog - used for herding sheep in the UK - is on average easier to train than a Bulldog (I own one, it is hard). The same is true of Arabian horses i.e. easier to train than average.",
"However... | [
"They did. It was called (and still is) ",
"eugenics",
"."
] | [
"Selective breeding doesn't create new genes, it only selects for existing ones or ones that arise through mutation. Canines do not currently have the genetic basis for human level intelligence, thus you can breed smarter dogs but not suddenly make them smarter than the genetics allow for."
] |
[
"If I recorded a completely silent room for 30 minutes, would the file have no size, or be average in size for a 30 minute recording?"
] | [
false
] | It makes sense to me, that since there is no input there would be no transcribed data, and therefore no file size. | [
"A completely silent room is not really silent, and the recording system will introduce noise anyway. But let's assume you want an artificially generated file with complete silence.\nThen it depends on how the data is encoded. For an uncompressed PCM format you get the same file size regardless of content. So 30 mi... | [
"Actually that has everything to do with the content. Some codecs do record constant zeroes for thirty minutes, while other are able to say \"repeat zeroes for the next 30 mins.\" and be done with it. This obviously has a huge impact on file size."
] | [
"Try this: ",
"http://en.wikipedia.org/wiki/Variable_bitrate",
"VBR allows a higher bitrate (and therefore requires more storage space) to be allocated to the more complex segments of media files while less space is allocated to less complex segments\"",
"What this means is that if there's a segment of silenc... |
[
"Quantum physics - how can the properties of a quantum particle change based upon whether or not it is observed?"
] | [
false
] | I was reading about the Quantum Eraser experiments, and from what I understand, photons (and other quantum particles) can exhibit different properties depending on whether or not they are being observed... It defies conventional logic to think that observation itself can affect reality in such a way. What is the signi... | [
"Observed doesn't mean \"looked at by a person\" in this context.",
"Objects in the quantum realm (their action is on the order of hbar) exist in a superposition of states. For instance, an electron in a box could be in a combination of its first and third eigenstates, or an electron in an atom could be in a supe... | [
"What is it that can force a particle to take on values in this way?"
] | [
"This. In quantum mechanics, as in much of physics, many terms mean something slightly different than they do in common usage.",
"Also, in QM, \"measurement\" and \"observation\" mean the same thing. It doesn't necessarily mean that someone went and measured the particle, but that the particle was forced to tak... |
[
"A question about sun protection"
] | [
false
] | Today we were talking about SPF and my girl-friend said that a bigger SPF protects you better but I said that it actually just protects you longer. Some research online showed that I was right so now I wonder 2 things: Now, let's presume you use it at the beach and you get in the water every 30 minutes and you re-apply... | [
"As a fair skinned person, I fully approve of this message. People like me have to buy specially made sunscreen which protects agains UVA, and UVB. It usually costs more, and is not nearly as redily available."
] | [
"what does \"the damage is in your skin not in in the sunscreen\" mean?"
] | [
"After the intended period of time the sunscreen is about the same, minus some hydration. On the other hand your skin is at its limit for sun exposure. A better sunscreen doesn't last longer against the sun, it makes your skin last longer."
] |
[
"If the universe is expanding, does that mean that we are physically expanding?"
] | [
false
] | [deleted] | [
"We are not expanding today because the \"dark energy\" that is expanding the universe is insignificant at small scales. The big rip hypothesis says that there may come a day when it is not insignificant and dark energy does cause atoms and even smaller particles to rip away from other particles."
] | [
"We are not expanding today because the \"dark energy\" that is expanding the universe is insignificant at small scales. The big rip hypothesis says that there may come a day when it is not insignificant and dark energy does cause atoms and even smaller particles to rip away from other particles."
] | [
"There are forces pulling us apart and pushing us together that are kept at an equilibrium at our current size. The expansion of the universe is not altering this equilibrium. If it suddenly expanded slightly, then it would pull us apart slightly, but we'd just spring back (or be torn apart completely)."
] |
[
"Can underwater objects be smelled?"
] | [
true
] | [deleted] | [
"Yep. Ever smell a cup of coffee? Tea? A bucket of urine?",
"Smell receptors detect molecules that are fat-soluable.",
"Taste receptors detect molecules that are water-soluable.",
"Might as well...",
"FWIW, there are about 5 \"primary\" tastes. If you've ever seen those tongue maps, they're total bullsh... | [
"Smell receptors detect molecules that are fat-soluable.",
"Acetic acid is not fat soluble yet highly odoriferous. "
] | [
"Can the particles which are [smelled] pass from water to air?",
"Yes. Gas particles can be held within water (think carbonated soda), and they can also be released (soda goes flat). ",
"Simple experiment: cook something! Imagine throwing fresh cut onions into a pot of water. Let it sit for a little bit, and... |
[
"Is it true that a single sperm holds 37.5MB of DNA data?"
] | [
false
] | This regards the post below. The comments didn't address validity. Can someone comment with some authority, and maybe expand a bit? I had never considered this before and I find is fascinating. Thanks | [
"a single spermium contains the haploid genome (each chromosome once with the exception of the sex determinative chromosme pair X and Y - there can be either X or Y in the spermium). a haploid genome with the X-chromosome has 1597 Mbp (Mega base pairs). there are 4 nucleotides - so the code is quaternary. Which mea... | [
"4 possible nucleotides for each base pair, so two bits per base pair. That's 3194 bits. 8 bits per byte so 399 million bytes which comes out as 380 MB (with 2",
" bytes per megabyte).",
"That's just a simple coding of the base pairs. I'm sure you could compress this a huge amount with different techniques. As ... | [
"In a haploid cell, there are roughly 3.2 billion basepairs of which only 1.2% are used for coding. This means, one sperm cell has 38,400,000 coding base pairs. Because each base pair stores 2 bits of information (the 4 bases can be defined by 2 binary bits) every 4 bases contains 1 byte. This means that one sperm ... |
[
"Why are some skills perishable, while others are not?"
] | [
false
] | Last evening I was reading a book, and it said something along the lines of 'unlike riding a bike, piloting an aircraft is a perishable skill.' This made me wonder: why are some skills perishable if we don't make use of them, while others, such as riding a bike, are things you can pick up even years later? | [
"Some skills are motoric coordination - like riding a bike, and others are cognitive processes, like what button to push when while flying a plane.",
"Motoric skills become hard-wired in your brain, you actually build the necessary structures that connect certain balance-governing reflexes with certain repetitive... | [
"what about flying a single person plane/helicopter. One that uses a lot of manual control vs a jet, would this get hardwired in your brain?"
] | [
"Speaking as a private pilot who has taking long lapses between flying, I can say that the most perishable skills are the ones that are least motor memory like. For example, after a break between flying (7 months) while I was able to fly the aircraft mechanically to get it to do the things it should do, things like... |
[
"Can the details of Big Bang Theory really be widely accepted when it is based on our knowledge of normal matter, which is less 20% of the matter of the universe?"
] | [
false
] | And we know very little about dark matter apart from that it exists. | [
"based on our knowledge of normal matter",
"No, it isn't. We have good reason to accept the big bang theory because it explains our observations. ",
" is the mark of a good theory. And until it fails to, it will be what we use.",
"The ",
"cosmic background radiation",
" along with ",
"redshift",
" sho... | [
"I think you might be misunderstanding OP's overall point (or I am)--he's talking about types of matter. Given that it's thought \"normal\" (baryonic?) matter constitutes only 20% or less of all the \"stuff\" in the universe, could that \"missing\" 80%--which we can't directly observe and measure (dark matter, etc... | [
"But we can only observe <20% of the matter in the universe. I'm not debating our theories on background radiation or redshift, more about particle interactions during the Big Bang. If we only have knowledge of particle interactions for 20% of the matter, how can we be sure we're not running into a situation simila... |
[
"Question about the probability of seeing the same car over and over in the city vs. seeing multiple cars of the same model."
] | [
false
] | [deleted] | [
"Hmm.",
"Assumption #1 regardless of how many Camrys there are, you have an equal chance of seeing any one of them. ",
"Assumption #2 you NEVER see more than one camry in a single viewing.",
"Place some number of black tokens in a pot to represent all the Camrys other than your own\nPlace a single white token... | [
"A lot of it depends, you might be seeing the same Camry in the same (or near the same) spot on a regular basis, travel/commuting patterns aren't fixed, but they're fairly regular for most. "
] | [
"Perhaps. I'm not that great at English but I was taught an idiot is someone who acts in a self defeating way. Drawing a comparison to the Monty Hall problem weakens his position as it is irrelevant."
] |
[
"Why does the moon look so big in this picture?"
] | [
false
] | null | [
"They've used a very long lens, for starters. That was shot at ",
"400mm",
" on a crop sensor camera (basically turning it into a 640 mm lens), which makes the moon look very large in the frame. That house is well over a kilometer or more from the photographer.",
"Have a look at ",
"this link",
" and co... | [
"It looks bigger near the horizon because there are other objects to use as a point of reference. When you look at that photo your brain already has an idea of how big that building actually is. Using that as a point of reference you can get an idea of the true size of the moon. When the moon is in the middle of t... | [
"This has more to do with neuroscience than astronomy. Once the moon is about 10 degrees above the horizon it looks small because we see it against the open sky. When it is at/near the horizon we see it in reference to everyday objects.",
"If you hold you thumb out at arms length and place it over the moon you ca... |
[
"Why does my microwave spark with certain foods?"
] | [
false
] | The microwaves a few years old, and all of a sudden it has started sparking a ton whenever I put certain foods in it. Potatoes, Waffles, and other random food. I've tried cleaning it out multiple times, but to no avail. I'm begging to think it has to do with air pockets? And no, I am not putting metal into it. -.- Than... | [
"I know a fair amount about microwaves, and have seen this for myself with an old microwave oven and diced green peppers (sparked every time). The best explanation that I have ever come up with is based on: 1) metals spark in a microwave oven because of their high conductivity 2) sparks/arcing only occur at geomet... | [
"Physics Forum",
": Why do Certain Vegetables Arc in the Microwave?",
"The ",
"USDA says",
" carrots and hot dogs are common sparkers: ",
"The ",
"Canadian Food Inspection Agency",
": ",
"A ",
"local news station",
" apparently reporting that Green Giant say it's due to mineral rich soil when it... | [
"Big Upvotes for the Scientific Method!"
] |
[
"How can light both reflect and refract off the same surface?"
] | [
false
] | I've seen images of a light ray striking a piece of glass and splitting, with part of the light being reflected and part of the light being refracted. How can different photons respond in different ways when striking the exact same piece of glass? | [
"Lovely question.",
"I think the short answer is that it boils down to the uncertainties inherent in quantum mechanics. When two particles interact, the outcome of that interaction will follow a probability distribution, and will only be predictable from a statistical standpoint."
] | [
"To clarify/add, while LARGE bodies interacting may seem deterministic (pool balls bounce off each other in a predictable way), the behavior of photons and other small scale particles is dominated by quantum effects. This means we can model behavior (to some extent) via probability distributions, but we can never s... | [
"You are assuming that the piece of glass is a uniform, homogenous continuum. But it's not and the quantum mechanical effects on the atomic level or the atomic structural level matters.",
"Here's a Richard Feynman lecture series",
" that deals with your question in Lecture 2. Although, I'd recommend watching th... |
[
"How does a string of codons become a human brain. What is the series of steps from A to Z in this process?"
] | [
false
] | I have a basic high-school / level 100 college biology understanding of genes and DNA, but I still don't understand how a string of codons can code for something as intricate as the human brain. 1) What are the major steps of the process from Zygote to the formation of the brain? 2) Are computers powerful enough to c... | [
"1) What are the major steps of the process from Zygote to the formation of the brain?",
"You basically asked \"how does the entire human body develop...\" there are many many steps from a simple zygote to a human. This isn't something someone can answer in a single post.",
"2) Are computers powerful enough to... | [
"You are asking some tremendously massive questions here.",
"Our nervous system (which includes our brain) develops from the ectoderm, the outermost layer of the embryo. At around three weeks, the ectoderm begins to thicken and forms the neural plate- which is where our brain cells (both neurons and other cells l... | [
"2 and 3 - No. We're having a hard enough of a time being able to generate computer simulations of proper protein folding (deriving the shape of a protein based on its sequence) without human intervention, much less account for the many",
" protein-protein interactions (IE: signaling pathways, transport, and othe... |
[
"How many recessive deleterious genetic conditions does the typical person have?"
] | [
false
] | I know that a lot of genetic diseases are rare (one in ten thousand or lower). But there are also a lot of them; what's the probability that I have one allele that would cause me to have some disease if not for my other, functioning copy? | [
"The probability of you carrying a given recessive allele is essentially incalculable. It depends on lots of factors, some of which you can measure and some of which are essentially random. ",
"The measurable stuff is evidence like your ethnic group. The genetics standby group, Ashkenazi Jews, have a much higher ... | [
"OP is assuming no epistasis (lots of genes for a given phenotype/condition rather than just one). As far as Mendelian conditions (the classical dominant vs recessive, one gene and two possible alleles scenario) 1cuteducky sums it up nicely."
] | [
"You make a good point about epistasis. I wasn't sure how much detail to get into on Reddit without zooming past the layperson's ability to understand it. I'd happily take suggestions if you have any -- I'm not much of a teacher, fortunately enough for the undergrads they don't make me teach... "
] |
[
"In python, why does print(0.1 + 0.1 + 0.1 - 0.3) return a non-zero number?"
] | [
false
] | null | [
"Humans represent non-integers as decimal fractions, a / (10 ^ b). For example, .1 = 1 / (10 ^ 1).",
"Some non-integers, in this representation, have an infinite number of digits; for example, 1/3 = 0.33333…. ",
"Those numbers don't have a decimal fraction representation, but can only be approximated. For examp... | [
"The reason is probably due to inaccuracies in floating point arithmetic. If you search on google you will find various explanations, ",
"such as this one on SO",
".",
"The reason explained in short is that there is a limited amount of real numbers that can be represented. Due to the representation choice, 0.... | [
"Floating-point implementations are sometimes inexact. In ",
"particular",
", some numbers can not be represented exactly. Floating-point representations have a base b (assumed to be even) and a precision ",
". If ",
" and ",
", then the number 0.1 is represented as ",
". If ",
" and ",
", then the ... |
[
"Do any known environmental variables impact general intelligence (g) long term?"
] | [
false
] | Not to confuse g with IQ - the latter is impacted by numerous environmental variables on the specific ability of a test question; the secular rise on IQ is known as the Flynn Effect, and is not on g. But general intelligence. The highest domain in factor analysis of cognitive testing of ability. I'm aware of this study... | [
"Do you agree that the Flynn effect is evidence to invest in each and every human being",
"Sure; with the caveat being they show interest.",
"If someone's interested in computer science/programming then I'm all for investing resources to get them into the field.",
"An educated populace in highly lucrative fie... | [
"This paper may be useful",
" for a theoretical framework.",
"There's some evidence that ",
"self-perceived abilities",
", ",
"financial resources",
", ",
"and early childhood stressors",
" affect IQ. The problem is the research is largely correlational, so it's hard to make big claims with it.",
... | [
"A very good question, but the current scientific community can't answer that for you, so neither can I.",
"Nobody really understands what exactly causes the Flynn effect, but it does exist. What's surprising to many is that, taking into account all the data from twin studies, the shared environment appears to ha... |
[
"Medical question - Any advice grateful"
] | [
false
] | null | [
"Sorry:",
"Medical advice is always off-topic and inappropriate. Please consult with a doctor regarding issues of health. Please do not ask for, listen to, or offer diagnoses, treatment advice, or personal medical opinions."
] | [
"CopyPaste response? I don't mind if you're not going to read it my post but you could at least modify the warning."
] | [
"It's against Reddit's terms of use, ",
" in the sidebar here. If we had to write out personalized \"No medical advice\" to the posts which need it, we could probably quit our day jobs. ",
"This is also off topic as you're asking for pointer to resources on how and where to get treatment and such. ",
"I wish... |
[
"Could a star have a stable ring system?"
] | [
false
] | [deleted] | [
"That's basically what an asteroid belt is, so yes. It would just have to be early enough in the system's evolution that gravity would not have bound matter together. Although it might not necessarily last the lifetime of the star. Even planetary ring systems coalesce."
] | [
"I think the presence of another planet is important in the evolution of an asteroid belt. Jupiter constantly disrupts our belt, which is what kept it from coalescing into a planet.",
"Absent that kind of disruptive influence, I believe all belts will coalesce into planets/planetesimals.",
"The rings around pla... | [
"The entire mass of the asteroid belt is about 3% the mass of the Earth's moon. So it would not really be a planet if it were all collected together in one body."
] |
[
"Is there radiation associated with the creation of a charged particle?"
] | [
false
] | I was studying for E&M and I noticed that radiation fields seem to be accompanied by a changing current somewhere. I then tried to figure out how to get radiation without a current this is the best I got. I know the question is kind of nonphysical since you can't just create a lone electron for example but supposing yo... | [
"I'm familiar with those, I was wondering what happened if essentially your charge density was a step function in time but wasn't accelerating (once it exists). The potentials are then discontinuous so my radiation fields don't make sense and I don't really get how you would deal with that. ",
"Edit: From what I ... | [
"Well you could try to work out the problem classically, by modeling the charge density as a step function in time times a delta function in space (two of them, one for the positive charge and one for the negative, since you'd have to produce a particle-antiparticle pair).",
"But that sounds like a nasty problem ... | [
"These",
" are the electric and magnetic fields produced by a point charge moving arbitrarily. Whenever the particle is accelerating, it produces electromagnetic radiation."
] |
[
"If we all descend from the same common ancestor (Mitochondrial Eve), why are we not all horribly inbred?"
] | [
false
] | I'm going to be honest - Biology isn't exactly my forte, which lies more in the physics department. If this is a really simple question, then I'm sorry, but it would be great to get an answer or two. | [
"The term \"mitochondrial Eve\" can be a bit misleading when devoid of context or explanation. No biologist or geneticist would suggest that all humans sprung forth from a SINGLE organism. Rather, we look at mutation rates and patterns and extrapolate backward towards the \"origin\". In real terms--as in, if we ... | [
"We are inbred, just that the gene pool is quite large.",
"Try this thought experiment - lets assume an isolated island with 1000 people on it, 500 men and 500 women. Call this initial set of 1000 people progenitors. Now take someone born 10 generations down the line and draw his family tree. He has 2 parents, 4 ... | [
"Despite the name, \"Mitochondrial eve\" was ",
" the only woman living at the time, not to mention the only human. It just happens to be that all living humans can trace back to her through their maternal line. So lots of people lived alongside mitochondrial eve, and lots of them had descendants that survive t... |
[
"If methane is such a potent greenhouse gas, why do the majority of environmental regulations focus on CO2 emissions?"
] | [
false
] | Does methane just get taken out of the atmosphere much faster by natural cycles than CO2? | [
"Methane is relatively quickly converted to other molecules by natural reactions, typically on ",
"a timescale of order 8-9 years",
".",
"According to ",
"wikipedia",
":",
"The major greenhouse gases are water vapor, which causes about 36–70% of the greenhouse effect; carbon dioxide (CO2), which causes ... | [
"The amount of carbon dioxide being emitted so greatly outnumbers the methane emissions that its affect on atmospheric warming is stronger. ",
"http://epa.gov/climatechange/ghgemissions/gases/ch4.html",
"\nIn the Methane Emissions figure you see that about 620 million metric tons of co2 equivalent are released... | [
"Right, but it seems like you would get more bang for your buck by focusing on methane emissions, since it is such a potent greenhouse gas. "
] |
[
"Where did the sun come from?"
] | [
false
] | I know the basics of how the *sun (stars) works. Clouds of hydrogen gas coalescing as a product of gravity until the density and heat reach a point of ignition. At this point, the sun is "powered" by a fusion process starting with hydrogen into helium, helium into carbon...etc. To my understanding, the fusion takes ... | [
"Hydrogen (helium too) is not found in our atmosphere because of its low mass. It literally flies away because gravity is not good at holding such fast moving particles.",
"http://en.wikipedia.org/wiki/Atmosphere#Escape"
] | [
"The idea is that there were clouds of hydrogen gas that had never condensed into stars. Then the debris from one or more supernovas hit that cloud, it added enough mass for the whole thing to begin to condense.",
"http://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System",
"A shock wave from a s... | [
"There was a lot more hydrogen in the solar system before the sun started fusing it. Once that started, hydrogen past a certain distance from the sun got blown out by the heat. There's very little around the planets because it's too light and easily achieves escape velocity."
] |
[
"If energy is quantized can't we say that mass is also quantized? And if mass is quantized doesn't that mean that there is some particle which can not be devided in anything smaller?"
] | [
false
] | null | [
"Energy isn't quantized in the same way that charge or spin is, in general. If that were the case, there would be inertial reference frames that aren't valid, because they would give objects kinetic energy in between quanta, which violates Lorentz symmetry."
] | [
"That said, in spatial terms, yes, we theoretically have a lower limit to size in our universe - The Plank length, 1.6×10",
" meters. You can't get anything smaller than that...",
"That's a common misconception. The Planck length is where our current models of physics break down and stop working. This doesn't m... | [
"Lorentz symmetry might well be violated when you approach the Planck scale; this underlies some very interesting ideas in quantum gravity. But if the OP's question was about \"normal\" quantum theory, where things like charge and spin are quantized (this is how I understood the question, anyway), then there's no e... |
[
"AskScience AMA Series: We are rare disease experts and directors with the NIH, ask us anything!"
] | [
false
] | Rare diseases and genetics: Rare diseases affect more than 300 million people globally, but few have approved treatments. Because the majority of rare diseases are genetic, gene-based approaches offer promise for developing new therapies. In observance of coming up on February 28, we're a team of experts here raising a... | [
"Dr. Collins, Dr. Austin, Dr. Pariser, thanks for doing this AMA.",
"It can often seem like there is ",
" at the NIH, where poorly understood conditions don't receive funding mainly because no one at the NIH is an expert in them yet, so there is no one to advocate for them, so extremely sick people are left to ... | [
"With COVID-19 cases surging there is an estimate that 10% of severely impacted COVID-19 patients will go onto developing \"long covid.\" Dr. Faucci and Deputy Director ",
" have said these people best identify with the Myalgic Encephalomyelitis patients and have expressed concerns that these symptoms could last... | [
"We do not yet know how many people will develop ME/CFS following infection by SARS-CoV-2 and we do not have data regarding the effect of the virus on people who have ME/CFS. I have recently started a study that ",
"will be following individuals",
" who are recovering from COVID-19 to understand how their sympt... |
[
"What prevents constant blood flow from eroding our blood vessels?"
] | [
false
] | Our hearts pump blood 24/7 for as long as we're living, and to my understand it flows quickly. Does this erode our blood vessels, and do they have to constantly combat it? | [
"So, you are probably mis-understanding blood flow. Blood flows fastest in the center of a blood vessel, and as you move outward to the wall, it slows down, until you get to the wall, which obviously cant be moving. This is called laminar flow. Blood flow can be turbulent, but only really in disease states (e.g. ar... | [
"You're spot on!",
"Nothing stops it - that pseudo factoid about our bodies replacing all of our cells or atoms in X amount of time is pretty much correct. Your blood vessels, just like your muscles, immune system and so on, are constantly undergoing repair processes to replace damaged and dead cells."
] | [
"Also blood vessels are stretchy! Especially major arteries that have to be able to cope with huge bursts from each pump of the heart."
] |
[
"When a railgun fires (video reference in post), what causes the fire blast?"
] | [
false
] | Reference video: When the railgun is fired, there is a combustive looking explosion trailing the projectile. Given that the railgun uses electromagnetic force to launch the object, what is it that causes the fire? | [
"This was in the comments.. Certainly appears to be relevant. ",
"Several effects are working here to create that explosion.\nFirst, as stated in a comment, is ohmic heating, created by the current through the projectile.\nSecond, the speed that the projectile is coming out of the barrel is high enough that the ... | [
"That is surrounding gas being ionized by the charge sent through the rail(s)"
] | [
"How would it ignite the oxygen present in the atmosphere? The oxygen must react with something, it can't just ignite on it's own. "
] |
[
"The minimum temperature for steam is 100c but is there a maximum temp?"
] | [
false
] | null | [
"So by 'steam' you mean water gas right? Well 100 ºC isnt actually the minimum temperature for steam. It is the minimum temperature at standard atmospheric pressure, but under different conditions you can have steam down to even -50 ºC. See the ",
"phase diagram of water",
" for more info. ",
"If you have a s... | [
"Im assuming you are doing this at a standard temperature like 25 ºC. ",
"Yes. You will get ice, but it might not be the normal ice you get in the freezer. Ice has many different structures depending on the conditions in which it forms. "
] | [
"Based on that phase diagram...",
"If I had 1 cubic foot of water and increased the pressure to 150kbars it would turn to ice? (all other variables held constant)"
] |
[
"What is a polymerase chain reaction?"
] | [
false
] | null | [
"https://www.genome.gov/10000207/polymerase-chain-reaction-pcr-fact-sheet/"
] | [
"You can find the basic answer with a simple google search / on wiki. Please check there first and come back with a more specific question."
] | [
"I read the wiki page and I was hoping someone here could explain it in a way I might understand better. Sorry."
] |
[
"Standing on the moon..."
] | [
false
] | How bright would moon appear to you if you were standing on it? Is it as bright as snow or would be or less? | [
"The moon has the albedo of charcoal ",
"looks like this",
"http://history.nasa.gov/alsj/a12/AS12-46-6807HR.jpg"
] | [
"12 ",
"http://history.nasa.gov/alsj/a12/"
] | [
"It only looks bright when your eyes are adapted to see in the dark, like at night. Funnily enough several Apollo astronauts compared walking on the moon with skiing on snow."
] |
[
"How does ASLR and DEP, and sandboxes exactly work and how do they prevent exploits in software?"
] | [
false
] | From the ground up can someone please explain how Address space layout randomization(ASLR) and Data Execution Prevent (DEP)? What types of attacks do they provide protection | [
"OK. I'm going to assume you understand some basic things about how programs are executed, but please ask if anything here isn't clear. I'll probably make a big edit at some point to make things easier if this thread gets a lot of upvotes.",
"To start with we need to understand a very basic attack called a \"buff... | [
"Hi, I just wanted to thank you for answering with such detail. I understand how the return will take the program to another part of memory (where code can be executed), but what I don't quite get is how does the return address exactly becomes overflowed with data? I mean how can he write more than what is allocate... | [
"So the stack is just a sequential bunch of addresses. You can think of it like a linear array. When you allocate a character buffer of 100 bytes, for example, the compiler creates 100 bytes of space on the stack for that buffer. The return address is right next to this space. So now if you write 104 bytes into tha... |
[
"How does tomato juice remove smells? Why is it more effective than many other natural and synthetic compounds?"
] | [
false
] | Edit: Should have posted this to ! Turns out, tomato juice is NOT more effective than many other natural and synthetic compounds. Damn you Spiderman (The Spectacular Spiderman, 2008) for inspiring this question after a fight at the dump. | [
"It doesn’t. That whole “bathe your dog in tomato juice if they get sprayed by a skunk” thing is a myth. (I’m a certified vet tech in an ICU now but when I was the new kid working in the kennels of a rural clinic 30 years ago I had to wash many a skunked dog. Please believe me that it does not work, now you’ve just... | [
"This is in wikipedia's ",
"list of common misconceptions ",
"Tomato juice and tomato sauce are ineffective at neutralizing the odor of a skunk; it only appears to work due to olfactory fatigue.[390] For dogs that get sprayed, The Humane Society of the United States recommends using a mixture of dilute hydrogen... | [
"The best remedy I know is to use a detergent specialized to cleaning wool. Why? Because skunks spray as alkaline. The rumors about tomato juice stem from this... Though the oils mostly prevent the tomato from neutralizing anything.",
"But wool detergents are acidic (wool doesn't do well with alkalines) and in... |
[
"Does anyone know where I can buy a DC tesla coil?"
] | [
false
] | I need and tesla coil with AC in and DC out. I've found plenty of plans on how to build one but I really don't have the time. | [
"Yes, what do you need it for? They are expensive and quite dangerous."
] | [
"I need it for a personal project. Do you have a site link?"
] | [
"High voltage isn't anything to fuck around with, if you've never worked with it before I wouldn't recommend using a tesla coil for your first time.",
"http://amazing1.com/tesla.htm"
] |
[
"How much mass must an object have to be an effective electrical ground?"
] | [
false
] | For example, you can ground jumper cables on the frame of car, yet it is insulated from the actual ground. I'm guessing it depends on the voltage/amperage, but what exactly is the math involved? | [
"I'm not 100% sure I understand your question. It has nothing to do with mass. It's about circuits. Current must always flow in a circuit. i.e. their must be a continuous loop of conductive material. The mass of the conductors does not enter into it.",
"\"Ground\" is often something that is defined as 0 volts. Bu... | [
"Essentially the earths size is so massive that it can absorb the extra electrons at a higher voltage state without changing the voltage of ground. Use the equation q=cv and assume the earth has infinite capacitance. The voltage of ground will not change with any addition of electrons. Voltage is similar to how man... | [
"I think the key bit of info that you need is that electrical grids are connected to the earth, so that the active line -> you -> ground forms a circuit. As for lightning, that works more like static electricity - lightning is actually a ",
" of a difference in charge between the clouds and the earth, rather than... |
[
"Planets revlove in an ellipsoid trajectory around the sun - but what are the foci?"
] | [
false
] | I imagine the sun is one since it's mass is a large source of gravitational force, but what is the other? | [
"Your assumption that the force of gravity produces only circular trajectories is false. I don't know how else to elaborate without maths."
] | [
"Generally, Newton's equation for gravity says gravity is an attractive force. So, wherever two objects are in space relative to each other, the force of attraction between them will be a vector that points from one center of mass to another.",
"For planetary orbits, where the mass of the orbiting body is general... | [
"One of the foci is, strictly, the centre of mass of the system, rather than the centre of the Sun itself, but effectively the difference is minute. The other focus doesn't have any astronomical meaning."
] |
[
"If a person is paralyzed from the neck down and cannot breathe on their own, how can their heart still beat on its own?"
] | [
false
] | null | [
"The source of the electric signals that drive the heartbeat is ",
"within the heart itself",
". The brain and the spine are not involved in setting the base pace (but they are involved in adjusting it in response to various stimuli). "
] | [
"This is correct. There are multiple sites within the heart that naturally set the baseline rhythmic electrical activity (SA and AV node), and if they should become damaged, the rest of the conducting system of the heart can continue to transmit and even generate rhythmic electrical activity, just not as effectivel... | [
"It depends on the organ. The lungs for example need innervation from the brain, and spinal cord damage can result in a loss of the ability to breathe. Specifically, I believe it's C3, C4, C5, (Phrenic nerve) which are necessary to keep the diaphragm moving. Otherwise, you'll need a mechanical respirator. ",
"Oth... |
[
"Can gravitational lenses (or a series of them) turn a light source back on itself?"
] | [
false
] | I (think I) get the concept of gravitational lenses being able to bend light a little bit, so could a series of lenses turn the light to be pointed roughly towards its source - albeit millions of years later? Secondary to this - theoretically could a distant star that we see at a certain point in time actually be our o... | [
"This can happen near black holes, where the path of light can be bent so much that it passes the event horizon. However, to modify the path of a distant star back to its direction of origin would require the perfect setup of perfectly placed black holes which is so unlikely as to never happen."
] | [
"In principle it could happen with neutron stars, too - light is bent sufficiently by neutron stars that about 2/3 of the surface can be viewed at once!",
"Well-placed galaxy clusters could also do this, although their effect is so minimal that I am not confident there is enough space within the current observabl... | [
"A follow-up question:",
"Would it be possible to return the light to its exact starting position traveling in the exact opposite direction, by gravitational lensing? ",
"I am having trouble visualizing a solution without a mirror - which of course isn't allowed. Math is appreciated."
] |
[
"Does falling through clouds get you soaked?"
] | [
false
] | ...since clouds are made up of billions of water droplets? | [
"It would have the same effect as passing through fog."
] | [
"To elaborate, if it is a raining cloud, then yes, you'll get soaked. Otherwise your experience with non-raining fog is the same experience that you'll have passing through a cloud."
] | [
"According to this ",
"F-8 pilot who had to eject over a cumulonimbus supercell",
", yes."
] |
[
"Are photons always a sine wave?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"A good home for this question is our sister subreddit ",
"/r/AskScienceDiscussion",
". It might be too open-ended or speculative for ",
"/r/askscience",
". ",
"/r/AskScienceDiscussion",
" is... | [
"Thank you, I've reposted on ",
"/r/AskScienceDiscussion",
", but I have to say as far as questions go, this is about as non open-ended or speculative as is possible. The question \"Are photons always a sine wave?\" is most likely a yes/no question (and if it isn't, surely it's at least a fairly direct question... | [
"The ",
"/r/AskScience",
" answer is \"No\", but if you want more, that needs to come from ",
"/r/AskScienceDiscussion",
".",
"The real question is (aside from that it's a pretty standard ",
"/r/askscience",
" question), if the post was removed, why didn't I get a message saying so, and also why was i... |
[
"Is there an upper limit on how large a freshwater lake or inland sea can become?"
] | [
false
] | At a certain point, do the minerals in the land around it become too much to ignore? Could an island or continent of significant size be 50% or more lake? | [
"The most important factor would be whether water is flowing into or out of the inland sea. The ocean is salty because rivers carry minerals into the ocean, then water evaporates, leaving dissolved particles behind, and rains back down as fresh water onto rivers and lakes that flow back down into the ocean, picking... | [
"Another factor is that the oceans have existed since the planet cooled enough to allow them to form. Inland lakes come and go."
] | [
"That way, oceans (or other bodies like the dead sea) are the final resting place of the minerals that make them salty. ",
"It's not whole minerals, but rather the dissolved ionic constituents of what were once many different minerals that make up ocean salinity. More importantly, think of the oceans as a sort of... |
[
"If you have a gas, of some sort, and fire neutrons at it how would the gas respond?"
] | [
false
] | When a neutron encounters an atom how would an atom repond? Besides a uranium explosion (where the neutron makes the atom unstable) I don't know anyother ways in which an atom may respond to it. Can a bombardment of neutrons cause a gas to emmit light? | [
"A few things can happen: the neutron and the atom can bounce off each other and go their separate ways, the neutron can be taken up in the nucleus creating a different isotope (often unstable), or the neutron can be absorbed and the new atom undergoes fission."
] | [
"When you say neutron and atom can bounce off each other what do you mean? Do you mean to say it hits the electron and is deflected, hits the nucleus and deflected. ",
"Since it is uncharged would only direct contact with another particle have an affect?"
] | [
"The nucleus. The scattering I presume is through the nuclear force, which is like a weakened version of the strong force.",
"This page sums it up well: ",
"http://www.igcar.ernet.in/nuclear/neutron_interactions.htm"
] |
[
"Would we be able to learn anything new from nuclear weapons testing using modern equipment?"
] | [
false
] | The last tests of a nuclear explosion (notwithstanding North Korea, which would not be likely to share any discoveries in any case) was in 1998, by India and Pakistan. The USSR stopped in '90; UK in '91; US in '92; and China and France in '96. Has equipment that might be used in such tests (like ultra-high-speed camera... | [
"(French here) There isn't much to learn since the last tests. The ones France did was to be able to simulate accurately further design of bombs in labs.",
"\nThe number one reason (if I'm not wrong) for tests is to try designs that gets the best yield for a given amount of nuclear fuel. \nYou'd never get a \"cle... | [
"Maybe, there's no other way to get energies that large. Testing nuclear weapons hasn't been about discovering new things in physics for a long time though.",
"From the 60's or 70's to the 90's, nuclear testing was mainly about validating that designs worked and that safety features worked. For instance, the ex... | [
"No. It is not currently feasible for anyone to go around picking up individual atoms at the bottom of the sea. ",
"One of the ways a bomb works is by taking a warhead that, by itself, is stable, and detonating it by exploding shaped charges around it to collapse it into a much smaller form, where the plutonium... |
[
"What is \"thirst\", on a scientific level?"
] | [
false
] | I have always assumed that we feel hunger when our stomach is empty, etc., and I'm sure various things (blood sugar levels, for one) change. But how does the body detect when we're dehydrated and need to drink? I literally have no idea. | [
"The thirst centres in your brain react to the concentration of your blood plasma, which is measured by \"osmolarity\".\nAn increase in osmolarity cause the release of a hormone, anti-diuretic hormone, which causes your kidneys to reabsorb more water, making your blood plasma more dilute and your urine more concent... | [
"There are also baroreceptors (receptors that sense blood pressure) found in some of your arteries, such as the aortic arch and carotid sinus, that send direct neural signals to your brain through the cranial nerves (CN X, the vagus nerve I am assuming since it is coming from the aorta) when there is low blood volu... | [
"When we feel 'dry mouthed' because we haven't had a drink in a while, is that because our water levels really are so low we are forced to slow saliva production, or is it a physiological 'trick' that our bodies use, to make the sensation of thirst unpleasant? ",
"I've often wondered why the feeling goes away so ... |
[
"Why are you not allowed to drink or eat anything after 12 am the night before surgery?"
] | [
false
] | Also this rule seems to apply if your surgery is at 7am all the way to 11 am the next day. maybe even longer? If your surgery is at 11 am couldn't you still eat and drink at 4am? | [
"The reason that we ask patients not to eat prior to surgery is mostly due to the risk of aspiration should someone vomit during induction. We want to ensure the stomach is as free of material as possible so that in the event you vomit you're not potentially introducing pathogens into the lungs."
] | [
"I couldn't possibly recommend adjusting your scheduling per what is outlined by the surgical team and their guidelines for a specific surgery.",
" have different guidelines depending on the anaesthetist, the centers themselves have different protocols and even the type of surgery being undergone.",
"Follow wha... | [
"Yes it's true that you really only need 12 hours of empty stomach time, but the reason that we ask you to not eat anything after midnight, regardless of your ",
" surgery time is that schedules are always changing. Imagine if there are 2 cases on the schedule and yours is the second one, scheduled for 3 pm. Now ... |
[
"Is it possible to have a temperature that allows ice and water to exist?"
] | [
false
] | null | [
"Yes, it is called the freezing point. Technically, the two would be in equilibrium, so it wouldn't be static, but as long as there is no heat exchange with the surroundings, the net amount of ice would never change with time."
] | [
"Basically,",
"Would it be possible to have a glass of water with ice in it, and be able to put it in an environment where the water will never freeze and the ice will never melt? Hard to fathom, but that would be cool. "
] | [
"be able to put it in an environment where the water will never freeze",
"If you're referring to an open environment then no, because heat exchange will either freeze the water or melt the ice depending on the ambient temperature. If you accept that no system exists in perfect thermal isolation then it is impossi... |
[
"Bremsstrahlung and General Relativity: Does a charge resting on the surface of earth emit radiation?"
] | [
false
] | The Standard Model treats gravity as a force like any other while General Relativity models gravity not as a force, but as the curvature of spacetime. A consequence of the latter is, that free-falling objects are force-free and their acceleration, defined as the covariant derivative of their four-velocity, is zero. Fur... | [
"It depends on the frame of reference. A charge at rest on the Earth does not appear to radiate as seen by other at-rest observers on the Earth, but a freefalling observer would see a charge-at-rest radiate."
] | [
"The energy of the emitted photon is not frame-invariant. There's no reason why it should be. The transition has a given energy in the rest frame, and it's Doppler shifted in any frame where the source is moving."
] | [
"The energy of the emitted photon is not frame-invariant. There's no reason why it should be. The transition has a given energy in the rest frame, and it's Doppler shifted in any frame where the source is moving."
] |
[
"Split Brain Patients, Are the \"sides\" aware of the other?"
] | [
false
] | I recently saw this video in : VS Ramachandran describes a patient in which one side believes in god and the other side does not. I also vaguely remember an episode of House that had a split brain patient but House is certainly not a reliable source of information for scientific inquiry. So my question is: in split br... | [
"since it seems that there are two consciousnesses existing in a single body",
"While consciousness is a tough thing to define (and is poorly understood), even in split brain patients there is really only one consciousness. There was a pretty good discussion of the phenomenon ",
"here.",
" ",
"Also, the co... | [
"Happy to! Based on his description, the person pointed to different signs \"using\" different cerebral hemispheres. All that means is that the person pointed to a different sign. While very interesting and certainly an important finding, you can't use that observation to say \"The person therefore has two disti... | [
"certain faculties that require the communication of both sides are affected by the removal of the linkage of two sides.",
"Yup.",
"Would a correct analogy then be: a brain is much like a network of computers or computational processors. The computers are divided into halves with several network links between t... |
[
"Is there a way to 'trick' our bodies into synthesizing and releasing epinephrine (adrenaline) on demand?"
] | [
false
] | I've been thinking about this for years, and just realized this would be the perfect place to ask! So, I know that adrenaline regulation is typically handled by our body without any conscious intervention (i.e., adrenaline is released when our body senses we're stressed or in danger). My question is that, with enough p... | [
"'drive like a maniac, speeding in & out of traffic and doing stuff on the road that is not considered safe'",
"\n'Every morning I tend to do something similar' ",
"Please stop doing this. You are endangering the lives of others."
] | [
"'drive like a maniac, speeding in & out of traffic and doing stuff on the road that is not considered safe'",
"\n'Every morning I tend to do something similar' ",
"Please stop doing this. You are endangering the lives of others."
] | [
"Well...",
"I think you could arrange for circumstances likely to leave you with a post-traumatic stress disorder. Then you might be able to fairly reliably trigger panic attacks by just thinking about the traumatic event.",
"I am not saying this would be a good idea."
] |
[
"Why isn't it possible to find the origin of the big bang? Also, what if you lived somewhere where you don't experience time like we do, would the age of the universe be different?"
] | [
false
] | Obviously that would be a difficult thing to do. But we think the universe is 14.7 billion years old. Why can't we trace it back that far and look in an area where it could of happened? If it was really that age would it be difficult? This also brings up another question. Say you live in a part of the universe where ti... | [
"To your first question, it's not that the big bang was at a certain place in space. The Big Bang ",
" the entirety of space, and space itself expanded. So the location where the Big Bang \"was\" is everywhere, which is why the cosmic microwave background radiation can be seen in every direction equally, no mat... | [
"I used this metaphor elsewhere recently, but I'll repeat it here.",
"Imagine you've got two dinner plates sitting a few inches apart on a piece of cloth. Something stretchy, like spandex. All your friends are standing in a circle, holding the cloth taut, so the plates rest of it pretty much like they would on a ... | [
"Well, that cleared it up pretty quick. :P"
] |
[
"Are the intestines \"in order\"?"
] | [
false
] | Ok, so this might be a strange question, but every time you see a depiction of the intestines it looks like a rope, that you try to fit into a small place without properly tangling it up. And if people in movies,tv etc. are severely injured, their belly sliced open and their intestines fall out, they kind of hang out o... | [
"Damn.. is there ",
" that's accurately displayed in movies?"
] | [
"I will answer part of this at least for non-human animals, but I think for humans as well (based on my talk with my colorectal surgeon).",
"In veterinary medicine, when we do an exploratory surgery or a bowel resection or some other surgery involving the intestines, they can essentially be put back in in any way... | [
"Thanks, that explains a lot. Is it possible at all for the intestines to \"come out\" like that?\n If yes, does that mean certain death or can they be put back into place ? Can the membrane restore itself ?\nThis of course assumes, the intestines itself aren't damaged too badly."
] |
[
"AskScience AMA Series- IAMA Medical Physicist working in a radiation treatment clinic"
] | [
false
] | Hey ! I am a physicist/engineer who switched over to the medical realm. If you have never heard of it, "Medical Physics" is the study of radiation as it applies to medical treatment. The largest sub-specialty is radiation oncology, or radiation treatment for cancer. The physicist is in charge of the team of technici... | [
"Do you think directed therapy, like focused ultrasound or magnetic nanoparticles, will become widespread?",
"What's the next new imaging modality? Cerenkov based detectors?",
"What's the coolest thing you could do with one of your machines if your boss was on vacation?"
] | [
"A lot of these newer therapies are really good for a very narrow range of tumors. My work with nanoparticles, for instance, would only be applicable either in tumors very close to the skin, or tumors that could be treated with very low-energy (~10 keV) photons. So I don't see many of them becoming widespread, be... | [
"Electrons are much cheaper - they are already on most clinical accelerators. But protons have much more attractive physics. Electrons scatter at larger angles from other electrons in tissue, so it is difficult to get electrons to travel in a straight line. This makes treating anything except superficial skin le... |
[
"If gravity is the curvature of space-time, then what is the graviton suppose to be?"
] | [
false
] | As I understand it, what we feel as "the force of gravity" is actually just a curved space time. I imagine it like a ball rolling down hill. I also heared gravitons are suppose to cause the force of gravity but it doesn't make sense gravity as a force when it's just a curving of space time. | [
"A graviton is a quantum of gravitational radiation, like a photon is a quantum of electromagnetic radiation."
] | [
"The ",
"metric",
" is the dynamical field in general relativity. For every other field theory (which we think describes nature) there are associated field quanta (particles) which are the minimal perturbations of the field around some background (if the backgrounds are, in some sense, extremal they are called ... | [
"It's a different formulation. If you start with the quantum model of a massless spin-2 particle, the classical limit will give you the exact same equations as Einstein's classical geometric model. You can even find some general relativity textbooks which take this approach. They both have issues: the completely cl... |
[
"How does lithium work to stabilize moods?"
] | [
false
] | As in, what does it do to the various transmitters and chemicals and receptors? Does it affect electrical potential between neurons? Is it the toxicity that makes it work? | [
"The exact reasoning isn't understood, but some researchers suspect \"lithium acts pre-synaptically, on receptors on serotonin-sending cells to enable more serotonin to be passed from one brain cell to another. They hypothesize that lithium also acts post-synaptically, on receptors on receiving brain cells, to enab... | [
"I am currently doing research in understanding how lithium treats bipolar disorder by attempting to synthesize a lithium specific fluorescent probe. That way it can be monitored in brain cells to see where the lithium concentrations disperse. This is accurate. They hypothesize that lithium substitutes for magnesiu... | [
"RadioLab did a fantastic piece on this. \n",
"http://www.radiolab.org/story/lithium/"
] |
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