title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"My girlfriend is making me banana pudding. What about brining the contents to a boil makes it thicken into pudding?"
] | [
false
] | She is making banana pudding and is boiling the milk, pudding mix and bananas. I'm at a loss as to why boiling it makes it thicken. Is the heating breaking down a sugar enough so that it can polymerize? like Jello polymerizing from gelatin strands? | [
"http://en.wikipedia.org/wiki/Starch_gelatinization",
"Starch gelatinization is a process that breaks down the intermolecular bonds of starch molecules in the presence of water and heat, allowing the hydrogen bonding sites (the hydroxyl hydrogen and oxygen) to engage more water. This irreversibly dissolves the st... | [
"Sure thing:",
"sugar, corn starch, artifical and natual flavor, calcium carrageenan, polysorbate 60, atrificial color",
"She added 1% milk also"
] | [
"To clarify, the OP didn't ask what ingredient makes the pudding thicken but why bringing it to a boil makes it thicken. In this case it his question would be what is it about boiling corn starch that makes it thicken."
] |
[
"In a mixture containing several types of molecule, can you selectively transfer energy to only one type? (In any given mixture of molecules)"
] | [
false
] | In spectroscopy, certain atoms or certain chemical bonds are known to absorb certain wavelengths of electromagnetic radiation. Does this extend to a larger scale? Do entire molecules have characteristic EM absorbances that might be used to selectively transfer energy to them in a mixture? Aside from EM waves, is there ... | [
"What do you mean by \"entire chemical structures\"? Molecules? Sure. They can have narrow absorption bands as well.",
"Note that these molecules transfer their energy to the environment quickly. You can heat regions with a higher concentration of your target molecule more than other regions that way, but you can... | [
"They usually don't list the energy levels, but you can compute energy difference pretty easily from the absorption peaks. ",
"Which NIST tends to have a good database for experimental spectrums.",
"http://webbook.nist.gov/cgi/cbook.cgi?ID=C7732185",
"That's my goto if I want to look up IR spectrums. "
] | [
"It is possible to calculate the energy levels of molecules with simulations, but looking it up is probably easier for common molecules. There are databases for that. I'm not a chemist."
] |
[
"\"It was pointed out in the 1970s that in a solid not only the charge and spin of electrons can become ordered—leading to magnetism—but also the electrons’ orbital degree of freedom.\" -- What does that mean?"
] | [
false
] | I saw the in about electrons being "split" into two parts, and the article in Nature had the titular sentence in it. What does it mean when electrons' orbital degree of freedom is ordered? Nature article . | [
"An electron (just like any particle or object) carries angular momentum. This angular momentum has two distinct components - the ",
" and the ",
" angular momentum.",
"Spin is an intrinsic type of angular momentum (unique to particles) which is characteristic of the particle you're dealing with. For example,... | [
"Thanks for the reply. What I'm trying to find out, though, is what it means for the electrons' orbital degrees of freedom to be ordered. How do the electrons act? When the spin and charge are ordered, that lead to magnetism. What's the corresponding thing for spin and orbital freedom?"
] | [
"I believe the work you are referencing has to do with electrons \"splitting\" into two quasiparticles - the spinon (which carries the electrons spin degree of freedom) and the orbiton (which carries its orbital degree of freedom). Although I'm not familiar with the details of this process, I can say that what's ha... |
[
"A question about hemoglobin oxygen binding"
] | [
false
] | Why does hemoglobin have higher affinity to oxygen at lower temperature and lower metabolism than at higher temp and higher metabolism? Does the higher temp denature the protein more? Thanks | [
"I don't think it has anything to do with denaturation. It's just ordinary chemical thermodynamics. The binding affinity in general gets lower at higher temperatures, because binding lowers the entropy (it's a more 'ordered' state), and higher-entropy states become favored at higher temperatures."
] | [
"There are several things wrong with this question.",
"you use the words \"denature\", which implies that the hemoglobin protein loses its order and becomes disordered. Hemoglobin is relatively heat stable, and so denaturation is not an issue for physiological conditions - and it's clearly not influencing oxyge... | [
"Oxyhemoglobin dissociation (",
"http://www.ventworld.com/resources/oxydisso/dissoc.html",
")\nat higher temps more O2 is needed fro the increased cellular metabolism thus shifting the curve. The HgB has less affinity to aid in the \"unloading\" of the O2 at the cellular level. "
] |
[
"Why do all species use only L amino acids?"
] | [
false
] | I learned in biochemistry that all living organisms only utilize the L configuration of amino acids, but if we were to somehow inject the D configuration into an organism could it utilize it and make proteins from it? | [
"A lot of bacteria use D-amino acids in pepitidoglycan synthesis as an example"
] | [
"I'm a biochemistry undergrad, so I'm no expert, but I what I was taught was that early in evolutionary history, L-amino acids catalyzed their own production and out-competed D-amino acids. You could make proteins with D-amino acids, but they would be enantiomers obviously."
] | [
"No, it could not utilize the D conformation because the D configuration would actually make a completely different product. They are sometimes used in proteins, though. The truth is, we really don't know why the L is preferred in the body. It is theorized that the L configuration is slightly more stable than the R... |
[
"What is a mud volcano? How often do they ignite when they erupt?"
] | [
false
] | Inspired by the news of a mud volcano erupting in Azerbaijan, I starting wondering how they form, and how they erupt. If they’re not typically associated with igneous volcanoes, how do they pressurize? Under what circumstances do you end up with a mud volcano – or one that ignites? Thank you! | [
"Mud volcanoes typically represent eruptions of \"overpressurized\" fluids and muds. A standard model for their formation would be in a location with very high sedimentation rates. In such areas, compared to regions with slower sedimentation rates, sediments do not have a chance to significantly \"dewater\", i.e. t... | [
"Basically because they share a common formation mechanism, i.e. very fast sedimentation rates. Petroleum systems need fast sedimentation to prevent the parent organic material from being broken down aerobically before it is buried and can be broken down anaerobically (which is what is required to produce the right... | [
"Thank you so much, this is a very helpful answer! Do you know why they’re often associated with oil and gas deposits?"
] |
[
"Can a perfectly rigid body become tidally locked?"
] | [
false
] | null | [
"Tidal locking is an interaction with the quadrupole moment of the body. So if you have an object which is rigid, but has a nonzero quadrupole moment, it will still undergo quadrupole interactions with other bodies around it.",
"However planets, and other objects which are approximately in hydrostatic equilibrium... | [
"Some corrections: ",
" ",
"Tidal locking is an interaction with quodrupole and higher moments. The other moments are typically neglected due to the dominance of the quodrupole moment in the expansion of the potential.",
" ",
"A perfectly rigid body would evolve to be in spin-orbit synchronization but this ... | [
"To become tidally locked one of the bodies needs to be deformation and subject to dissipation. ",
"Two perfectly rigid spheres will not evolve due to symmetry. If there is asymmetry (a deformation similar in shape to a tidal deformation. There are others but just to keep the imagination simple) then there will b... |
[
"Is it possible to make a \"silicon diamond?\""
] | [
false
] | Diamonds are made when all four of carbon's bonding sites are linked to other carbon atoms in a diamond lattice. Silicon also has four bonding sites. Can it link to itself in the same way? | [
"They don't look like diamonds. They look like ",
"this",
"."
] | [
"Diamond has a huge bandgap and therefore is considered an insulator by usual standards. Most light can't be absorbed. Silicon's bandgap, on the other hand, is pretty small (in the infrared) so it absorbs visible light frequencies."
] | [
"http://www.flickr.com/photos/imager/3380554807/",
"Here we go. Image fully attributed to owner of that flickr album."
] |
[
"What methods/equipment do lab doctors use to test blood?"
] | [
false
] | I am interested in the journey that blood goes on once it is drawn by a phlobotomist. What machines or methodologies are used to test blood for a given condition or result. | [
"This is what I do on a day to day basis. It's a whole field of Pathology known these days as Blood Sciences, which encompasses Chemical Pathology, Haematology, Transfusion science and Immunology. Chemical pathology is the biochemical investigation of substances dissolved in blood, Haematology is the study of the c... | [
"Thanks so much for taking the time to write this super detailed explanation. You've given me so much info and further reading links. I really appreciate it."
] | [
"No problem, thanks for the award! My first."
] |
[
"Why can we separate an electric dipole into positive and negative charges (e.g. electrons and protons), but cannot separate a magnetic dipole into north and south poles (monopoles)?"
] | [
false
] | Obviously electricity and magnetism are intimately related. For example, moving a charge through a conductor produces a magnetic field, i.e. putting a compass near a live wire and observing the needle move perpendicular to the flow of electrons. On the other hand, moving a magnet field through a conductor produces an... | [
"Well, we live in a universe where apparently magnetic monopoles don't exist. It's hard to beat empirical facts.",
"There are condensed matter systems where you have things that are ",
" magnetic monopoles, like spin ices, where you can essentially have the two ends of the dipole really widely separated."
] | [
"You and the rest of the physics community ;)",
"Dirac showed that the existence of just a single monopole in the universe would imply that charge is quantized. Charge ",
" quantized, but we still haven't seen any monopoles."
] | [
"It's worth noting that there are very few branches of theoretical physics that ",
" allow for magnetic monopoles, we just can't seem to find them and no one knows why. "
] |
[
"AskScience AMA Series: I'm Astronaut Terry Virts: An Insider who can tell you about leaving planet earth! Ask me anything!"
] | [
false
] | Hi Reddit, I'm Col. Terry Virts. I'm a former astronaut who commanded the International Space Station from 2014-2015. I also spent two weeks piloting the Space Shuttle Endeavour in 2010. During my time in space, I took more than 300,000 photos of earth, conducted hundreds of experiments, did everything from shooting an... | [
"Hi, hope you’re having a nice day! I have a few questions: \n1. What do you do in your free time on the ISS?\n2. What responsibilities does a commander of the ISS have compared to the other astronauts?\n3. What is it like to go outside on a spacewalk? Is it terrifying or are you just focused on the task at hand?"
... | [
"1) not a lot of free time, but I used mine to take photographs and help film the IMAX film \"A beautiful Planet\"",
"2) They are the person in charge, ultimately responsible for everything. They also spend more time communicating with the bosses back on earth, at NASA and the other space agencies.",
"3) cool! ... | [
"Yes the ISS commander is the commander of everyone.",
"2) I did- it was profound seeing Earth from a distance. To borrow my crewmate Samantha's words, it is obvious that we should all be crew and not just passengers on spaceship Earth.",
"3) I think there was a married couple back in the space shuttle days, bu... |
[
"How does an action potential 'jump' to/from successive nodes of Ranvier?"
] | [
false
] | As I understand it, saltatory conduction in myelinated cells is when an action potential 'jumps' from one node to another. But how can the impulse just 'jump' like that? | [
"the myelin insulates the covered area from capacitance. since the inside of the cell is negative and outside is positive, ionic movement can get stuck to the cell wall and slow down significantly. kind of like if it were electromagnetic friction. furthermore ion channels rather than being spread out through the en... | [
"Mostly true, but just to clarify (as I did above, sorry) the ions entering the neuron through the calcium channels at the node of Ranvier do not diffuse down the axon as part of the current passing through. At least, this diffusion (which is almost negligent) is not what carries the current of the action potentia... | [
"Thanks for the reply! So how does the action potential reach the node if there is this insulation from myelin?"
] |
[
"When scientists say they have found a gene that does ?. What exactly have they found?"
] | [
false
] | When scientists say they have found a gene that does "whatever", What exactly have they found? | [
"I believe they're just stating they found the genetic sequence which codes for a certain protein which is known to carry out a particular function. The protein may be found in only a particular species, or there could be variants across species with a very similar function and polypeptide configuration/sequence. T... | [
"I work on molecular genetics. Basically they are saying that for a given animal behavior or cellular process, they have identified the/a molecule which is involved in that behavior or process, and determined the DNA sequence which codes for that molecule. ",
"To give an example, my lab studies temperature sensin... | [
"When scientists report that they have found a gene that is \"important for\" or \"involved in\" X, they literally mean that is it necessary but the exact function may or may not be known. This information can come from a knock-out of the gene, or from any of a number of types of screens. For example, lets say yo... |
[
"As oxygen is produced by photosynthesis, is the proportion of atmospheric oxygen lower in urban centers? If so, how much lower, and does it affect human health?"
] | [
false
] | It seems logical that it would be. I did some research myself using University of Google, but so much of what I found was from unreliable quack health sites that I thought I'd ask the experts. :) | [
"Yes it does, but if you measure it accurately, you will find that there will be more oxygen near water and on water compared to land, due to algae and photosynthesizing bacteria, and especially phytoplankton which produce quite a considerable sum of oxygen.",
"However, the proportions of oxygen in cities to coun... | [
"Please do not speculate in AskScience. This is a place for science."
] | [
"The products of oxygen combining with other things, i.e. sulphur, nitrogen, or just oxygen, is more significant, as they are far far more dangerous than just oxygen levels being low."
] |
[
"When a chameleon changes color, does a chemical reaction occur on it's skin?"
] | [
false
] | [deleted] | [
"No. Chromatophores, which are parts within certain cells, are responsible for the visible change. From what I remember from biology, chromatophores may contain pigments, reflect light, or both, to induce the change. According to Wikipedia, chameleons use cell-signaling via hormones or neurotransmitters to \"activa... | [
"To put this another way: the pigments are in the cells the whole time. When you see a color change, what's changing is the position and distribution of the pigments. For chameleons specifically, the dark-colored melanin granules are moved around. Some sources for further reading: ",
"1",
", ",
"2"
] | [
"You answered the intent of the question well, which I believe was \"is the color change itself a chemical reaction. I'd like to note that any living organism in homeostasis will constantly have chemical reactions going on its skin.",
"As a bonus, here's a video of some neuromuscular electrical stimulation on s... |
[
"Do you get wet from water in space?"
] | [
false
] | I understand that liquids form a ball in space, due to 0 gravity. I was wondering, if you touch (a ball of) water whilst in space, do your hands get wet? Does water attach to your skin or does it "bounce off"? | [
"Water blob in the face in space"
] | [
"Water maintains its cohesive and adhesive properties in space. In layman's terms: water is just as wet in space as it is on Earth."
] | [
"First you have to find water in space, but I am assuming you mean an astronaut in a space shuttle playing around with those blobs of juice or water. The technical answer (the best kind!) is that, yes, you would still get wet. Gravity has nothing to do with the process. The phenomena is somewhat dully named ",
... |
[
"What are some good data analysis programs?"
] | [
false
] | I'm an undergrad in a chemistry laboratory and I'm looking for a program (preferably free) to graph a few thousand data points and fit multiple trendlines to the graph, I'd need to be able to add my own trendlines with set slopes, etc, and also fit trendlines to data. Excel doesn't cut it and is near impossible to use ... | [
"Excel doesn't cut it and is near impossible to use for my purposes.",
"That seems... unlikely unless you're on a severely memory-limited system. First thing I was going to say was \"why not excel\". Fitting \"a few thousand\" data points is pretty trivial.",
"Most data/math programs should be able to handle th... | [
"You should put in the time to learn r. It is perfect for data analysis and has lots of great packages to help.",
"This is a great place to start.\n",
"https://www.datacamp.com/",
"People also often post examples or their r work with the code here\n",
"http://www.r-bloggers.com/"
] | [
"I have run into issues with Excel and large numbers of data points myself. Here are two issues with Excel:",
"1) Old versions of Excel have strict ",
"memory limits",
". This has caused crashes for me before. 64 bit versions of Excel massively improve on this limit, so I haven't seen these crashes on any rec... |
[
"When did humans become aware that it is our brain/head that does the thinking? What was the prevailing idea before that?"
] | [
false
] | [deleted] | [
"Alcmaeon of Croton",
" is often considered the first to posit that the brain is the controller of consciousness and perception, but I feel like I remember reading that some Ayurvedic doctors knew about it in vedic times, I'll keep looking and add it to this comment if I find it."
] | [
"Cool, thanks!"
] | [
"Thanks a lot!"
] |
[
"In order for a virus to survive, as it mutates is it more advantageous for it to cause fewer symptoms so it can be more easily spread? Would SARS-CoV-2 be seen as more \"successful\" if this happened more frequently over time?"
] | [
false
] | null | [
"I would say yes. Humans as a whole wouldn’t make a huge deal if it didn’t produce symptoms, which would make it easier to spread and thus more successful. There are already examples of viruses that are mostly chill and infect a huge portion of the population, such as Epstein-Barr virus and cytomegalovirus (I think... | [
"Infact, Covid 19 is a milder more infectious relative of the SARS virus. So what you just mentioned already happened. ",
"Successful pathogens infect faster than they kill their hosts. Ebola had a morbidly high mortality rate, so we were able to eradicate it by simply isolating the patients and waiting for them ... | [
"It depends. COVID is transmissible via respiratory droplets so its survival and transmission in the population is caused in large part from its ability to cause symptoms of cough, sneezing, etc. This is what enhances its spread. So COVID that is relatively asymptomatic will spread slower. It would, however, be adv... |
[
"Why do we use FeCl3 in the production of Egyptian Blue and Prussian Blue?"
] | [
false
] | After I saw the production of Egyptian Blue, I started to wonder, "Why do we use FeCl3?" It isn't part of the reaction itself, as the reaction itself is: CaCO3 + CuO + 4SiO2 → CaCu[Si4O10] + CO2 This lead me to try and search for the answer online, but I haven't been able to find the answer. | [
"As prussian blue is iron(II,III) hexacyanoferrate(II,III) it should be more than obvious why you need FeCl3 for that.",
"Regarding egyptian blue: I have never heard or seen anywhere that you would use FeCl3 to synthesise it. What are your sources on this?"
] | [
"That sounds like an error. I have never seen any synthesis of egyptian blue with iron(III)chloride."
] | [
"I'm a chemistry student, and in our inorganic chem lab we where supposed to use it in the porcelein boat, along side 0.158 g CaCO3, 0.125 g CuO & 0.240 g SiO2 before placing it at 1000C for 4 days.",
"",
"I say supposed, as due to COVID we didn't get the chance to actually do the experiment."
] |
[
"Why can humans safely eat raw fish (sushi) and beef (steak tartar), but not raw chicken or pork."
] | [
false
] | What is it about some fish and beef that make them safe to be eaten raw? | [
"Pork has a high incidence of trichinosis and chicken has a high incidence of salmonella, but in principle you could eat these animals as safely raw as you can fish and cows if they were kept free of these diseases."
] | [
"Trichinosis is almost nonexistent in developed countries ",
"CDC",
". Avoiding raw pork is mostly a holdover from when it was everywhere.",
"Salmonella in chickens is still a major problem, though."
] | [
"Just a note, BSE is caused by a prion. As such, cooking has little effect on beef contaminated by it.",
"As for sushi, most fish meant for sushi is frozen before being used. This kills the parasite (mostly)."
] |
[
"Where does the heat from fire (and other exothermal reactions) come from? It's clearly caused by some kind of thermal radiation, but what particles are involved, and what is the process in their creation?"
] | [
false
] | Every time I see a combustion reaction in a chemistry class, it's always (Hydrocarbon) + Oxygen => CO2 + Water + heat (Imperfect combustion notwithstanding) When asking where the heat comes from, my teacher always says "energy released during the reaction", and that's not detailed enough to my liking. | [
"Well to answer that, you have to understand what \"heat\" is. And how it's carried.",
" Very roughly, heat is the average kinetic energy carried by a collection of particles. I say very roughly because the actual definition is related to the change in entropy with respect to change in energy.",
" In a material... | [
"The details of where the heat specifically comes from is complicated. Chemistry is (essentially) all about electrons: where they are and where they're going. ",
"Imagine that electrons in molecules/atoms are balls resting on shelves at various heights. When a chemical reaction takes place, the heights/arrangemen... | [
"Energy is released when bonds are broken, then that same energy is used to form new bonds.",
"It's exactly the reverse: energy is released when new bonds are made, and energy is required to break bonds. A fire heats you because the combustion products contain stronger bonds that released energy through their for... |
[
"Do the earth and the moon orbit a central point somewhere between the two?"
] | [
false
] | [deleted] | [
"The Earth and Moon orbit about the center of mass of the Earth-Moon system, which is located on a line between the center of the Moon and the center of the Earth, about 1000 miles below the surface of the Earth. "
] | [
"Not always!",
"My guess is that when Jupiter and Saturn are on the same side of the sun, they pull the barycenter outside of it."
] | [
"Yes. In fact the Earth does not orbit around the Sun. The solar system orbits around a common center of mass"
] |
[
"Astronauts on the ISS are floating because they are constantly falling, but what about the Apollo astronauts when they were in between the Earth and the Moon? What's the difference between 0G from an orbit, and 0G from simply being in space?"
] | [
false
] | [deleted] | [
"Free fall is free fall no matter where you are. If you are in an airplane (like the \"Vomit Comet\" NASA uses to train astronauts) that is accelerating downward at the same rate as you, then you will be weightless there too. The point is that weightlessness is an artifact of being in a ballistic trajectory--no rea... | [
"TLDR: You're in \"zero g\" when you follow the same ballistic trajectory as the vehicle you're in. No matter where."
] | [
"After leaving orbit, the Apollo spacecraft was no longer accelerating, it was \"falling\" toward the moon (it had enough velocity to continue to move away from the Earth, and eventually move into the moon's gravitational field)."
] |
[
"What qualities made iron better than bronze for weaponry and armour?"
] | [
false
] | Historically, the Bronze Age was followed by the Iron Age and weapons and armour followed suit. What particular properties of iron made it such a useful material for weapons and armour, compared to bronze? Did bronze have any qualities itself which would have made it a better choice than iron? Edit: To clarify, I'm ask... | [
"From Wiki:",
"Though bronze is generally harder than wrought iron, with Vickers hardness of 60–258[3] vs. 30–80, the Bronze Age gave way to the Iron Age; this happened because iron was easier to find and easier to process. Bronze was still used during the Iron Age, for example officers in the Roman army had bron... | [
"Tin makes up approximately 10% of bronze, so it is easy to see why a shortage of Tin would significantly increase the price of Bronze; however, I think it is very interesting that the Iron Age followed the Bronze Age for largely economic reasons. "
] | [
"Well, that paragraph makes it pretty clear that economic reasons were responsible for the advent of the iron age. ",
"Bronze is superior in hardness to wrought iron, melts at lower temperatures and is more resistant to corrosion. Apart from economic reasons, i.e. price, availability, there is no reason to switch... |
[
"Does the height or weight of a golfer effect the distance a golf ball can travel?"
] | [
false
] | I saw a question online that asked, "If a man and a woman both hit a golf ball with a club head speed of 100 mph, a +1 angle of attack, and a straight club path. Who would hit it further the man or the woman. The man is 6'-2" and the woman was 5'-6". Also the man is heavier." The person who posed the question said both... | [
"i think you are assuming a larger swing radius because of the height difference, but wouldnt the length of the arms be more relevant?"
] | [
"For starters, let's assume that:",
"1) The ball is struck at the point where the club head stops accelerating, and starts to deccelerate. At this point, the acceleration of the club head is 0, and the club head has reached it's top speed, 100 mph.",
"2) The velocity of the ball = velocity of the club head ( t... | [
"Your logic is flawed. Club speed at the moment of impact causes the acceleration of the ball. Nothing to do with the acceleration of that club speed by the golfer. They are separate events. ",
"Although, longer arms could technically effect spin of the ball when considering follow-through because of the differen... |
[
"When performing the deadlift exercise, what is the physics/kinesiology behind the fact that mixed grip is much stronger than double overhand grip?"
] | [
false
] | To clarify, here is a picture of the deadlift exercise, which also details the conventional (double overhand) as well as mixed grip (over/under grip): In the fitness community, it is well known that the mixed grip allows you to lift much heavier weights, but what I'm wondering is why this happens. Is it related to the ... | [
"as long as your hands aren't too sweaty, the path of least resistance for the bar is to roll out of your hands due to the shape of the bar and the nature of your hands. if you have a pronated grip, it only has to roll in one direction. if you have a mixed grip, it has to roll in two directions. you're reducing the... | [
"It definitely allows you to lift more weight - at least it does for me.",
"When I deadlift double-overhand, my max capacity tops out at about 330lbs before my hands simply can't grip the bar hard enough to stop it from unrolling my fingers and falling out of my hand.",
"When I use a mixed grip, I can hit my cu... | [
"It definitely allows you to lift more weight - at least it does for me.",
"When I deadlift double-overhand, my max capacity tops out at about 330lbs before my hands simply can't grip the bar hard enough to stop it from unrolling my fingers and falling out of my hand.",
"When I use a mixed grip, I can hit my cu... |
[
"Why hasn't evolution caused mammals to have many more females than males?"
] | [
false
] | In most mammals our birthing cycles are long. So, I was thinking.. optimally as a specie to survive, wouldn't it make more sense to have X females per male? Since most of the historical evolution has been based on survival, why has the sex ratio in all mammals remained close? Why don't we see mammals where there are 10... | [
"The underlying reason for this conundrum was first outlined by Ronald Fisher and is still known as ",
"Fisher's Principle",
". It doesn't just hold true for mammals, but for most sexually reproducing organisms.",
"To explain why, first I have to clear up a bit of a misconception. You say:",
"So, I was th... | [
"This really explained it well/succinctly for me. Thanks."
] | [
"Yet beware of \"",
"truthiness",
"\": the gut feeling that if something seems reasonable to you, it is likely to be true.",
"It seems obvious to us now that the continents shift (S. America fits right into Africa), but it was equally obvious to our predecessors that continents are big, immobile chunks of roc... |
[
"Why do insulin injections create an area of \"hard skin\" and is it happening with other forms of injections too?"
] | [
false
] | I've been wondering this for a long time. Is it some way of the skin saying that it's hurt and or are reparing itself. Or is it simply a result of not giving the proper massage? Should new injections be made in these "hard" areas or should they be left alone? | [
"Hardening under the injection site is caused by overdevelopment of fat and some scar tissue. The medical term is ",
"lipohypertrophy",
".",
"This is due more to the medication than to technique. Insulin encourages the development of fatty tissue, and massage does not appear to help. ",
"What does help is t... | [
"That's a different phenomenon. Dialysis access sites are surgically created and are usually a permanent fixture.",
"Patients who will be getting routine, long-term dialysis must have surgery to create a vessel that can tolerate lots of repeated needle sticks and very high blood flow. These sites tend to be reaso... | [
"I went to college with a guy who had to have dialysis for quite some time and had large odd looking lumps on his arms. I asked him about them and he explained they were from needles being inserted repeatedly causing scar tissue to form. One of the lumps looked to protrude around 15-20mm from the rest of his skin."... |
[
"If you use a bug-spray can as a flamethrower, can the fire actually flow back into the compressed can and cause it to explode?"
] | [
false
] | [deleted] | [
"Generally not. Aerosol cans do not usually contain an oxidizer, so atmospheric oxygen is necessary for combustion. What could, however, be an issue is if the heat from the flame heated the can enough for it to rupture."
] | [
"There is a common occurence in gas/oxygen welding known as Flashback, which is the condition of the flame propagating down the hoses of an oxy-fuel welding and cutting system. To prevent such a situation a flashback arrestor is usually employed. The flame burns backwards into the hose, causing a popping or squeali... | [
"Or if the can had been used to the point of being near atmospheric equilibrium, at which point the fuel to oxygen mixture might be just right for the can to ignite on the inside. There shouldn't be a huge reaction though, because at that point you wouldn't have much fuel left."
] |
[
"Do we currently have the technology to properly mitigate against Peak Oil?"
] | [
false
] | null | [
"If you read through the studies, most issues with fracking are caused by companies trying to cut corners and costs. When done properly, there should be very little long term environmental impact and impact on ground water. ",
"Fracking offers tremendous benefits for future technologies due to creating cheap pric... | [
"You’re right; our energy consumption rate will certainly not drop, and clearly with current infrastructure and power plants can certainly not be sustained. I think one of the main issues with shifting from oil today is that throughout mankind’s existence, we’ve had an addiction to burning/combusting things. This c... | [
"With the exception of your first point, what you say is pretty ridiculous, bold, and wrong. We cannot possibly have more coal or oil today than ever before if we have used some. Every source I have seen also says that our consumption is greater than both reserves and future growth.",
"Oh, and it doesn't answer... |
[
"When a liquid fueled rocket is launched, do they let the stages burn themselves out or are the shutdown at a certain time/height?"
] | [
false
] | null | [
"With a liquid fueled rocket, they are shut down because running them dry can cause explosions in the turbopumps."
] | [
"Very true. However that remaining amount is often part of the safety margins, so its going up anyway. Offhand, I do know they often run the fuel/oxidizer mixture a bit richer the close it gets to shutdown to prevent explosions and facilitate a clean shutdown."
] | [
"I would assume that under ideal conditions you'd want to calculate that pretty closely, as \"every additional kilo that you have to boost is very expensive\", etc. "
] |
[
"Why is digital preffered over analog when digital is limited to just on and off?"
] | [
false
] | I have done some basic reading on the two systems, but as in the title I cant quite wrap my head around the concept. shouldn't analogue circuits be able to transmit more information since they are capable of operating at different voltages, or is there something I am missing ? | [
"Analog signals also have a ",
"data limit",
"! Noise (which is unavoidable) will limit the accuracy that you can get from an analog recording. On the other hand, as soon as you record the ones and zeroes of a digital recording, you can reproduce it perfectly from then on. The fact that digital signals are defi... | [
"shouldn't analogue circuits be able to transmit more information since they are capable of operating at different voltages, or is there something I am missing ? ",
"You are right if you have only one information channel e.g. one wire and unpredictable data (which would sound like noise if it where audio). Then a... | [
"\"Digital\" in the sense I think you mean-- used for transmitting information through a channel-- is not just 0 or 1. I think you may be assuming all digital signals are binary. Digital signals are not necessarily binary, although they are necessarily discrete-- your signal could have four different discrete val... |
[
"Is the byproduct of the flame from a butane lighter any different from that made from a wick (specifically a wick made of hemp)?"
] | [
false
] | null | [
"I'm commenting on my phone so this may not be the best answer. ",
"With that aside the answer is likely yes, you'll have many more organic compounds in a hemp wick which will result in incomplete combustion products similar to what is in natural tobacco smoke, wood fire smoke or cannabis smoke such as hydrogen s... | [
"As a note butane was selected for use in lighters because of how cleanly they combust"
] | [
"..and a burning wick (or any other similar substance) will also release a lot of incompletely burned particulate matter...otherwise known as soot. The butane will not produce anything like that except under conditions of limiting oxygen (which is not normally the case)."
] |
[
"Sick in space?"
] | [
false
] | People get sick due to germs from other people/animals all the time. Do astronauts on the ISS or anywhere in space get sicknesses such as the common cold? | [
"The ISS is an isolated environment so if none of the astronauts have a cold when getting there then there's no reason to expect the pathogen to arrive.",
"However there is a meaningful chance to get some of the so called ",
"opportunistic infections",
" due to microgravity effects. Those are diseases caused ... | [
"Oh wow that's pretty serious. Thank you for the links."
] | [
"Or is sickness more common due to the fact that our immune symptoms have adapted to protect us from everyday germs because we've already encountered them? Introduction to alien germs would cause major damage because it is new and our bodies need time to create antibodies. "
] |
[
"Why does humidity affect how we perceive temperature?"
] | [
false
] | Example: 80° at 90% humidity feels a lot hotter than 80° at 40% humidity. | [
"Because we control our body temperature by sweating, and high humidity reduces the rate of evaporation, making this method of temperature control less effective. When water evaporates you lose 2260 kJ/kg of water, but when it's very humid, the water accumulates on your skin instead of evaporating."
] | [
"http://en.wikipedia.org/wiki/Wet-bulb_temperature"
] | [
"The amount of water in the air at 100% humidity on a hot 95F day is still very insignificant. Also water vapor is actually less dense than air thats why when a low pressure system moves in it generally rains/snows/precipitates. The amount of water in the air is very low. Looking at a stoichiometric chart at 25C wi... |
[
"Statistically speaking, is the general population becoming more or less religious as our understanding of the universe increases?"
] | [
false
] | null | [
"The west is becoming less religious but places like Africa and the Middle East are becoming more religious. ",
"Map of religions",
"The understanding part is much harder because it isn't just about the discovery, it would need to include education, book access, internet access, etc. There will also be other f... | [
"There's a wiki article on the correlations between education and religious beliefs. ",
"https://en.m.wikipedia.org/wiki/Religiosity_and_education",
"Atheists are better educated on average, but certain religious groups have an even higher average level of education."
] | [
"Historians and social scientists have been debating the so-called 'secularization thesis' for a few decades now, though with particular focus on Europe and North America. Callum Brown has an excellent book on the British example, \"The Death of Christian Britain\". Nancy Christie and Michael Gauvreau have good wor... |
[
"How do rockets prevent electrostatic discharges within their exhaust plume as seen in volcanic eruptions?"
] | [
false
] | Volcanic eruptions generate massive thunder within their plumes due to the friction between ash particles. How do rockets avoid static sparks like this in the high pressure exhaust that can charge with static and generation of ions from heat? | [
"Keep in mind that these plumes are very different. As you said, volcanic lightning is (probably not exclusively) related to volcanic ash. Volcanic ash is very different from normal ash: it is basically tiny (sand-size or smaller) pieces of volcanic rock, very often in very irregular shapes.",
"Combustion of rock... | [
"Hmm yes I considered that. Volcanic ash isn't ash- the combustion product, but pulverized rocks of below 2.5mm (size range i think)",
"Certain rocket fuels do produce solid particles. The H2 fuel one doesn't (water vapor), but others do, with the exhaust plume containing particles like alumina and carbon particl... | [
"I imagine those solids must be at pretty low concentration? Just thinking that the ash cover is often extensive after a volcanic eruption, and I'm not aware of it being significant at launch pads.",
"Rocket and volcano plumes still seem like very different scenarios to me, but I'm not really a rocket expert."
] |
[
"What is it like outside our solar system?"
] | [
false
] | I've been watching a lot of Star Trek: The Next Generation lately and it got me wondering about the space between solar systems. If a ship was out there (not in any planetary system in particular), would the crew be able to see outside the ship? I don't imagine the light from our sun would be strong enough to be a s... | [
"In Star Trek the ships are typically self-illuminated, for what it's worth. I know that doesn't address the question, but fanwanking it. (This is a point of stress in shows like Voyager, where they're constantly \"low on power\" but the entire ship is lit up, holo decks running, etc.)",
"But you're correct that ... | [
"Well \"self-illuminated\" certainly answers the \"how can ships see each other in sci fi shows\" question. I figured they wouldn't, but with FTL and Warp Drives, self-illuminated ships isn't really that hard of a reach to make. ",
"I didn't mean glowy, for what it's worth, I meant something like ",
"this",
"... | [
"Well \"self-illuminated\" certainly answers the \"how can ships see each other in sci fi shows\" question. I figured they wouldn't, but with FTL and Warp Drives, self-illuminated ships isn't really that hard of a reach to make. Would you be able to elaborate on the other parts of the galaxy that don't have a loc... |
[
"Why does it take longer for drinks to get cold than get warm?"
] | [
false
] | Or do drinks cool/get warm at the same rate? | [
"Say you have two drinks, one that's 20 degrees below room temperature, one that's 20 degrees above room temperature. Now, you take both of these drinks, and place them on your counter, with a thermometer attached to each. What you'll see is that the temperature of the cool drink rises exactly as fast as the temper... | [
"I'm not sure what you're asking. Are you asking why it takes longer for a warm drink to cool to room temperature than a cold drink to warm to room temperature?"
] | [
"Well, this isn't really true. It's only \"easier\" because we have devices meant for direct-heating in our kitchens.",
"I'm guessing it's a problem he has with defining hot and cold.",
"If you consider cold as \"below room temperature\", and \"hot as above room temperature\" (say 25C), then something that's 5C... |
[
"Quantum Entanglement Evidence And FTL Communication"
] | [
false
] | [deleted] | [
"Correlation doesn't imply communication. I don't follow your thinking here. If I randomly choose between two objects (say a cube and a sphere) and send one to you and one to your friend, then you know upon receinving a sphere that your friend received a cube. The two events are correlated, but you can't communicat... | [
"I think you are confused about how entanglement works, which is leading to why you think this communication is possible. ",
"You and I each have entangled particles. I know if I measure mine and get spin up, you have to get spin down. But what I don't know is \"have you measured yours already?\" There is no way ... | [
"The problem is that we can't manipulate an entangled quantum state to give desired results without breaking entanglement symmetry. We can confirm entanglement because the random results we get conforms to predictions."
] |
[
"Numerically, what's the most efficient way to organize denominations of money and their subunits?"
] | [
false
] | The US uses coins valued at 1¢, 5¢, 10¢, and 25¢. The EU uses coins valued at 1c, 2c, 5c, 10c, 20c, and 50c. What system makes the most practical sense so that a person could make change with as few quantity of coins as possible? Example: Let's pretend that the US Dollar only used $1 bills and pennies. Making a $0.25 p... | [
"These systems are already pretty close to ideal. The most efficient system would be evenly distributed along a ",
"logarithmic scale",
". For example: 1, 2, 4, 8, 16,... or 1, 3, 9, 27, 81,.... The Euro system gets as close as possible to being a log base 2 system and still hit all multiples of 5. The American... | [
"There's another interesting issue which depends on what denominations you have available. Suppose you need to give change for the amount of X, what type of coins (or notes too for that matter) should you give so that you give the smallest number of coins possible. As an example, suppose you need to give change for... | [
"What system makes the most practical sense so that a person could make change with as few quantity of coins as possible?",
"This needs to be defined better. You could ensure that change could always be made with a single coin by having coins of every denomination from .01 to .99.",
"But having 99 varieties of ... |
[
"Would the assembly of the ISS have been cheaper if the NASA used traditionnal rockets instead of the shuttle?"
] | [
false
] | I have been hearing criticism toward the shuttle for being terribly inefficient, yet I also heard others claim it was great for assembling the station. | [
"Almost certainly.",
"It's a simple comparison of cost per launch, to payload deliverable to LEO per launch. At around 50K pounds of lifting capacity to 450,000,000 per launch we can say the Space Shuttle spend about 9,000 dollars per pound it pushed into orbit. By contrast, the Saturn V could throw over 300,000 ... | [
"But to assemble the ISS, the Saturn V would have had to carry something capable of manoeuvering the payloads, so it's a bit more complicated right?"
] | [
"That was my thought too. The Space Shuttle's maneuvering arm was enhanced specifically for ISS assembly operations. In addition, the Saturn V/Apollo only supported 3 astronauts, the Space Shuttle supports up to 7, which may be necessary for assembly missions. It would certainly be possible to modify the Saturn V t... |
[
"Has any research been done on what the perceived center of a polygon is?"
] | [
false
] | I was looking up some stuff on geometry, and came across the concept that there's no one specific 'center' of an irregular polygon (although there are many different competing centers, like the centroid and the incenter for a triangle). However, I've noticed for some shapes, such as a crecent-moon-type shape, the centr... | [
"Just by searching I found these three that appear to partially address your question:",
"http://rd.springer.com/article/10.3758%2FBF03211785?LI=true",
"http://rd.springer.com/article/10.3758%2FBF03211786?LI=true",
"http://psycnet.apa.org/journals/xhp/27/3/692/",
"None of them seem to include shapes like cr... | [
"Interesting, thanks! I don't have access to those journals, so do you mind summarizing their findings?"
] | [
"The other centers 'discovered' would be center of gravity, or minimum moment of area or a system. These are the same thing, and are mathematical constructions and can be done for any sort of shape or set of points."
] |
[
"If the universe was spherical, would it be theorically possible to see the earth in the past ?"
] | [
false
] | As per wikipedia : Current results and analysis do not rule out a bounded global geometry (i.e. a closed universe). It would be possible to see multiple images of the same object, at different times of its history depending on the time light took to reach us. Lets assume technology is not a factor, is it then theorical... | [
"As far as I understand circumference would be more accurate than diameter. This whole question takes a little visual imagination due to space being a 4-d surface, while a sphere only has a 2-d surface.",
"Say space is 2-d. If you looked in a particular direction, you would see along a great circle (i.e. a circle... | [
"Provided the diameter of the closed universe was less than the age of the universe (fewer light years across than years age). For multiple images the diameter must be a proportional fraction of the age.",
"And there would need to be an unobstructed path to the images.",
"And a telescope with sufficient resolvi... | [
"Well yes, except that embedding the 2d surface onto a sphere is purely for the sake of an analogy to illustrate closed surface expansion. Such embedding is arbitrary and should not be taken too literally. The circumference you refer to is a property of the sphere in which the surface is embedded - not the surface ... |
[
"How do we know the newly discovered galaxy is \"the most distant\""
] | [
false
] | I understand fundamentally how red shift works, and that different stars emit different wavelengths of light, and that wavelength is related at least in part to the size of the star. What I don't get is: when comparing two stars, we say the redder wavelength star (further red-shifted) is further away... how do we know ... | [
"You're quite right to think that a redshifted \"plain\" black body light curve would be impossible to distinguish from a curve matching a cooler, unredshifted body - this is why the Cosmic Microwave Background, which has been redshifted immensely from its original state, is still the best black body spectrum out t... | [
"I don't know about you, but for all the people that complain about reddit being a waste of time, I just say that they're not browsing the right subs. Because honestly, meandering through reddit shows/reaffirms to me how many brilliant, and casually brilliant, people there are around us. I have no idea who these re... | [
"This is extremely interesting, thank you for sharing!"
] |
[
"Why isn't artificial evolution used to create all sorts of things?"
] | [
false
] | Considering that evolution can be reproduced with computers( ), I would think that it would be used to create all sorts of things. For example you could use evolution to create a super chess player. If you randomly generate chess players(as software I mean) and make them play against Deep Blue, mix the best ones and ad... | [
"It is happening, and its a viable way to attempt to solve some problems. ",
"Its just its slow, computers today are simply not strong enough and fast enough to run through the millions and millions of simulations and make so much progress. ",
"If you wanted, and had access to a supercomputer, you might be able... | [
"Hey! A question in my field! I'm a CS PhD candidate who is working with genetic algorithms for code simplification, synthesis, and repair. I have witnessed the birth of new programs from nothing, and it was good.",
"Here's the skinny: genetic algorithms (GAs) aren't some magical device that makes everything bett... | [
"It will never, therefore, branch out and create raw new code for itself. (I guess its possible if someone wrote an engine that actually does code development as well, but this seems like it would end up being very slow and unstable.)",
"Actually, ",
"genetic programming",
" is a model of evolutionary computa... |
[
"Could physical space have fractional dimensions?"
] | [
false
] | If objects can exist in 1 dimension, 2 dimensions, 3 dimensions, and so on, could there also be, say, 3.5 dimensional objects? | [
"Consider for one moment, do we have any mathematical circle in our universe? There is no ideal circle in nature. There are only objects which are adequately described and conceived as circles.",
"By the same token we have numerous objects around us which are better understood and described as fractals. A tree or... | [
"I don't think I am equipped to properly answer your question, but I strongly recommend you watch this ",
"3blue1brown video on what a fractal really is",
" and perhaps also read the ",
"Wiki article on fractal dimension",
".",
"Hope that helps!"
] | [
"Given an appropriate definition of \"dimension\", you can have sets of points that have fractional numbers of dimensions. They're called ",
"fractals",
". But as far as anyone can tell, these mathematical models don't correspond to any real physical objects or spaces.",
"TL;DR apparently not"
] |
[
"Did sex ever \"switch\" in evolutionary history?"
] | [
false
] | In high school biology, we learned that, in humans, females typically develop into females because they carry "XX" chromosomes, while males carry "XY" chromosomes. According to , the genetic mechanisms of sex determination vary between different kinds [clades?] of animals—so birds, for instance, typically develop chara... | [
"Or was there a period where sex wasn't determined by chromosomes but instead by some other mechanism, and then mammals and birds just happened to independently develop this chromosomal system of sex determination later?",
"This is the correct answer.",
"Hermaphroditism is by far the exception among animals, an... | [
"I think the other answers here are already good, but I just wanted to add an additional interesting point. Though almost all mammals do use the same XY sex determination system, this only dates to around 150 million years ago, while the divergence time between mammals and birds is at least double this. The most ... | [
"It is possible that the common ancestor of birds and mammals didn't use genetic mechanism of sex determination. For example, crocodiles, who are closely related to birds, determine sex based on the temperature during the egg incubation.",
"Birds and mammals might have evolved genetic sex determination independen... |
[
"Does this article about possibility of modified Alcubierre drive have any truth to it?"
] | [
false
] | There was a slew of news today about some kind of modifications that will make Alcubierre drive a realistic possibility. For example: I think this is the article from which it all began (PDF): So does it talk business? Ar at least can an experiment about spacetime bending described there be conducted? | [
"Does this article about possibility of modified Alcubierre drive have any truth to it?",
"In short, yes but not in the sense that it's being presented (hint: there's still no reason to believe warp drives are actually possible). For a longer version, see ",
"here",
", where I addressed the paper as part of t... | [
"The Alcubierre drive is a legitimate solution to Einstein's equations, but it breaks other rules which make it most likely impossible. Mainly it requires exotic matter, which is matter with negative mass. As far as we know that doesn't exist. And there's good reason to believe that it can't exist.",
"Furthermore... | [
"Exotic matter",
"Magic. It's like imaginary numbers in math. Everything makes sense with the numbers, but you can't actually have an imaginary number of anything."
] |
[
"I read somewhere that the AC travels on the surface of a conductor and the DC travels through the entire volume of the conductor. Why does this happen?"
] | [
false
] | null | [
"It's called the ",
"skin effect",
"."
] | [
"So your typical stranded wire pretty much behaves like a solid conductor albeit with slightly worse resistance (due to the material having air gaps in it). This is why a 12 awg stranded conductor has a slightly larger diameter than 12 awg solid conductor. The overall effect is due to the electromagnetic fields act... | [
"The company I work for makes huge industrial power supplies for chlorine production, water desalinization, metal refining, etc. We deal with tonnage of copper busbar. I once asked why they layer up many \"leaves\" of busbar instead of making one solid conductor and the answer is skin effect. The many layers negate... |
[
"What are sparks composed of?"
] | [
false
] | Are all sparks composed of the same thing? Or are they just electricity? I want to know all about sparks.. | [
"I'll try and provide a tentative answer, but maybe someone with more expertise should add something. An electrical spark occurs when the voltage in an insulator exceeds the material's ",
"dielectric strength",
", and that material undergoes ",
"electric breakdown",
". When this occurs, that material (in th... | [
"This is correct. Electricity is the flow of electrons through conductors, which occurs without any obvious change in the properties of the conductor because electrons are loosely bound and free to move between atoms. In a spark, the electric breakdown and resulting ionization frees electrons, allowing them to mo... | [
"Not all sparks are electrical. Non-electric sparks (such as sparks from a grinding wheel, flint, fireworks or sparklers, or even just a campfire) are simply fragments of material that have been heated hundreds or thousands of degrees and thrown off the main body. For instance, striking iron or steel can shave off ... |
[
"How close is our solar system to 'the edge' of the galaxy?"
] | [
false
] | Our galaxy itself contains a hundred billion stars; It's a hundred thousand light-years side to side; It bulges in the middle sixteen thousand light-years thick, But out by us it's just three thousand light-years wide. We're thirty thousand light-years from Galactic Central Point, We go 'round every two hundred million... | [
"Around 90% of the Milky Way's stars lie closer to the galactic center than ours does,",
" so in that sense, we are pretty far out.",
"In distance, not so much. The galactic disk does not have a well defined extent, but its main component (the \"thin disk\") is well approximated as having a scale length around ... | [
"That dark matter halo is an interesting aspect. Given that we are only 2.5 million light years from Andromeda, and assuming it has a similar halo, there isn't that much space between our galaxies."
] | [
"Apologies for just a picture from Wikipedia, but here is a pretty detailed ",
"map of the Milky Way",
". Sun is in the bottom middle, labels indicate directions to various constellations in the sky. All the Mxx and NGCxxxx refer to respectively the ",
"Messier Catalogue",
" and the ",
"New General Catalo... |
[
"Why can't non essential organs (1 kidney or the pancreas) infected with cancer be completely removed and the person be cancer free?"
] | [
false
] | null | [
"As long as the cancer is entirely contained within the organ, then yes, it can be. And this is done. It is generally step one of cancer treatment - physical removal of the tumour, where possible.",
"But by the time a cancer causes symptoms, it is rarely entirely contained within a single organ. Further treatment... | [
"Because cancer is made of cells, cells multiply, body is in constant motion, therefore the cells move. They may be centred in one place but, much like a zombie apocalypse, one infection can spread quickly and undetected, and every infected cell needs to be exterminated."
] | [
"Well, it depends on different factors. For one, if the cancer is hereditery it can show itself in another place in your body even if you remove one organ.",
"\nAlso I would think (not completely sure on that) that organs are only removed if one is dealing with a rather late-stage cancer. Such a disease in itself... |
[
"Why does sped up music sound higher pitched?"
] | [
false
] | I really can't get my head around why the play speed should affect pitch. Here's an example: | [
"Another word for 'pitch' is 'frequency', which is measured in Hertz (Hz), or cycles per second. If you speed up music, it goes through the same number of cycles in a shorter time, therefore more cycles per second, therefore a higher frequency.",
"Music is made up of many frequencies played simultaneously, but a... | [
"Refer to ",
"here on frequency",
". Speeding up a sound without modifying it in any other way means removing portions of the sound wave at a constant interval (or rather, skipping past parts of the wave at a constant interval), resulting in the frequency of the sounds having peak to troughs that are closer to... | [
"Play speed affects pitch if you simply compress the time scale of recorded music without changing the wave shape. On the other hand software exists to change tempo and pitch independently, like ",
"this example",
". In that case, the software has to change the wave shape. "
] |
[
"Can an event horizon \"cut\" objects?"
] | [
false
] | Assume it was possible to stay a short distance (a meter or two) away from a black hole's event horizon without crossing it/being torn to shreds. If you were to stick part of an object through the event horizon and then pull back, would the object be perfectly "cut," or would the whole object have to be sucked into the... | [
"I got this thought experiment after reading that for some absurdly large, super massive black holes, the force of gravity at their event horizons wouldn't be lethal, or perhaps not even noticeable (to a human, that is). ",
"This got me thinking, say a human wore some type of special suit specifically designed to... | [
"Large enough black holes will allow you to enter the event horizon unharmed from gravitational tidal forces.",
"So, you can find a black hole in which OP's question is valid enough."
] | [
"Well, the thing is, the pull of a black hole inside its event horizon goes to a kind of infinity - all possible paths in space-time end up in the center, no matter what forces are applied to a particle of matter. But there's nothing unique about the surface of an even horizon, which depends on the observer. The co... |
[
"If you were to be in a tank of water on a rocket/space ship leaving the planet, how much of the g forces would you feel at lift off?"
] | [
false
] | null | [
"Why is everyone saying you'd sink? People generally float in water at 1 G, because the water is more dense than a person, overall. When the rocket accelerates, that water is going to want to slosh down, same as you get pulled down.",
"At more than 1 G, the buoyancy force will increase by the same fraction as you... | [
"I believe you would 'feel' them less, due to this information from the European Space Agency:",
"https://www.esa.int/gsp/ACT/projects/liquid_ventilation/",
"They claim you can withstand 24 G's. If you could implement liquid breathing, they don't really know what the limit is, perhaps hundreds of G's. This is... | [
"Does water being incompressible factor in? Would imagine there is a threshold where a squishy human body is denser than water."
] |
[
"How could Graham's Number cause a black hole in my brain?"
] | [
false
] | null | [
"We already have a thread ",
"here"
] | [
"That is similar but I'm not asking about the number itself. That thread doesn't answer my questions."
] | [
"We have a subdiscussion about microscopic vs macroscopic information and entropy specialized to black holes there, have you checked that out?"
] |
[
"A Question About Viruses and Drinks"
] | [
false
] | [deleted] | [
"viruses are commonly stored in labs at -80 degrees C, so this strategy wouldn't work :)"
] | [
"good to know thanks. i've always wondered"
] | [
"Neither of these points are necessarily true."
] |
[
"The gravitational constant?"
] | [
false
] | null | [
"Sorry I don't really understand your question; what do you mean by: ",
"If I were doing a simple sandbox and just wanted to work out say, a ship landing on a planet could I just drop it if there is nothing else in the sandbox bar the ship and the planet? ",
"You mean like, if you were trying to create a phys... | [
"G = 6.67384 × 10",
" m",
" kg",
" s",
"It is just a constant where everything that matters is put in, and it is constant for all masses and distances."
] | [
"Well, you can't just drop something because it's a constant...",
"then you get a wrong force influencing the two masses.",
"But if you mean why this constant is there... It is an ",
"empiric value"
] |
[
"Question about the age vs. the size of the universe"
] | [
false
] | If everything started traveling at the speed of light away from the center of the Big Bang, and assuming that the universe expanded roughly spherically, and the universe is 13.7 billion years old, shouldn't the maximum distance between any two objects diametrically opposed at the surface of that sphere be 27.4 (13.7*2)... | [
"The answer to your question is that since the Universe is expanding, the distance that light travelled a while ago is larger now than it was when the light traversed it. The distance light has travelled in 13.7 billion years can only be 13.7 billion light years if there's no expansion to make that distance bigger.... | [
"Yes, it's similar, although the reasons are different."
] | [
"Let's say you have an infinite sheet of paper (or universe). You say the center is in one place, I say it's two miles over. How do we determine who's right?"
] |
[
"If the universe remained a constant size, could it run forever?"
] | [
false
] | If the universe suddenly quit expanding and remained at its current size, could it run forever; the same processes running over and over again for eternity? Energy cannot be created or destroyed, so the amount of energy would remain constant. | [
"Basically, no. Stellar fusion (which powers stars) depends on having a supply of light elements (hydrogen, helium, etc), which will eventually be exhausted (technically some may still be produced, but not in the quantities necessary). So the stars would all (eventually) go out. ",
"Additionally, it's likely t... | [
"surely larger molecules would decay into hydrogen molecules again",
"Okay first off for clarity, it's nuclei not molecules. However, this is a legitimate question. And in fact, for very heavy elements (such as uranium) that process will take place, and is what I was referring to when I said \"some may still be... | [
"Right, and to add to that, those heavy elements like uranium are built using the energy given off from gravitational collapse of heavy stars (like in supernovae as you point out), and there is only so much gravitational energy that can be extracted from the matter we have."
] |
[
"Is there a psychological reason for bridges in music, or is it just a consequence of western musical development? (Maybe both?)"
] | [
false
] | [deleted] | [
"I'm a classical musician, and one concept that might be interesting to you is the concept of flow in music. Western music developed with this idea of forward motion or direction as the expressive element, where many styles of Eastern music are more static and meditative. Western music is bit more like storytelling... | [
"Music instructor/musician/songwriter here. Great explanation. To add to this a little, when I'm working with young songwriters I like to explain a bridge as a moment to heighten suspense, to introduce something new to the listeners ear. It's commonly used in contemporary music to build into a final release of what... | [
"Thanks for this. I'm a classical musician as well, and I try to teach this concept to my students with varying levels of success. Of course they have a subconscious understanding given that they have been listening to these forms their entire lives, but it has never been codified for them. I think I will now start... |
[
"How is the source of a fire determined?"
] | [
false
] | I see investigations of house fires etc. on the news stating that the fire began from, for example, the bin. How on earth can they tell that from a burnt down house? | [
"This",
" is a pretty good explanation."
] | [
"That Straight Dope article is pretty good. I have some arson and explosion investigation background, and can offer some quick pointers.",
"Damage is followed back to the origin. Good origin and cause determination begin with a survey of the entire structure: a walkaround. Check to see if electric was working at ... | [
"The investigators in this case were more like shamans than scientists. The real scientists are the reason we know this man was wrongfully executed. There is a also a documentary: Frontline: ",
"Death by fire",
". "
] |
[
"What makes a high, basic pH so dangerous?"
] | [
false
] | We’re studying pH in one of my science classes and did a lab involving NaOH, and the pH of 13/14 makes it one of the most basic substances. The bottle warned us that it was , which caught me off guard. I was under the impression that basic meant not-acidic, which meant gentle. I’m clearly very wrong, especially conside... | [
"There are some great explanations in this thread, and I wanted to add a medical example. Base chemical burns on the eye are worse than acid chemical burns because of the different way the chemicals damage the tissue. If you accidentally splash a strong acid in your eye, it damages the tissue by denaturing it (chan... | [
"Great question. Simply put, acids donate protons, which will disrupt molecules including our cell membranes, proteins, etc. Bases are the other side of spectrum, meaning they don't donate protons, but steal them. This can be equally disruptive to a material including our cells. Adjusting the pH with acids or bases... | [
"To help illustrate the effect of bases consider lye (sodium hydroxide), a crucial component of soap. Basically take lye and any fat and mix it together in water. The basic solution will tear apart the fat molecules and turn it into soap. Getting lye on you can be really bad chemical burns because it turns pretty m... |
[
"why do things that seem unrelated to the electromagnetic force have charge? does every particle have a charge?"
] | [
false
] | mostly im talking about quarks, how does that work? also, furthermore, what is the difference between positive and negative charge? and how does that factor into the whole idea if electromagnetism? | [
"huh. weird. also neutrons are neutral but their constituent parts are charged if i remember correctly."
] | [
"huh. weird. also neutrons are neutral but their constituent parts are charged if i remember correctly."
] | [
"Constituents of Neutrons, quarks, do have charge, yes. However, the added charge of those three quarks is 0. Within such a small space (up to the size of the nucleus of an atom), the Strong force is stronger (no pun intended) than the EM force and the EM force basically won't matter. Once you get beyond the size o... |
[
"Can you deafen an insect?"
] | [
false
] | My limited understanding on the subject leads me to believe that many insects have small flaps of skin that can cover a large portion of their body that operate similar to how our ear drums do. Is this the case? And if so, can you make an insect deaf with loud noise or noise from a specific frequency? | [
"It is called a tympanum. The membrane can be damaged by a loud noise or mechanically. I once did an experiment related to mate location that required making cricket's deaf by damaging the tympanum. I don't know anything about a specific frequency working on it. "
] | [
"How did that work out?"
] | [
"So male crickets \"sing\" (by rubbing their limbs together) to attract females. We wanted to see if that was the only attraction used by them. So, we damaged the tympanum on the female crickets and then set them loose at varying distances from a male cricket. We found that those within a certain distance would fin... |
[
"Does lightning have observable depth?"
] | [
false
] | As in, when lightning strikes is it more like a line (2-D) or a cylinder with appreciable depth on the macro scale? | [
"Lightning is simply a stream of ionized particles (also known as plasma) moving from two bodies due to the electric potential between them. (Most commonly a cloud and the earth)",
"Electrons are point particles and technically have no volume but the channel in which they travel can be a couple of inches wide. ... | [
"Definitely has depth. ",
"I take it you haven't heard of Lichtenburg figures? They are essentially what's left behind after a massive electrical discharge. ",
"En.wikipedia.org/wiki/Lichtenberg_figure",
"Some people have gone so far as to make it into an art form. Here's an example from CapturedLightning.com... | [
"you are very right sir. Clarification: the 'electrons' are the thing that is moving."
] |
[
"Humans in arctic climates (such as parts of Canada and Greenland) traditionally eat a diet consisting of almost exclusively meat. Would a person of different ancestry (aka me, a white American) be able to thrive on such a diet or are genetics a factor?"
] | [
false
] | null | [
"There are relatively well documented instances where groups of Europeans subsisted on an Inuit-style diet for long stretches of time. One such instance is sir Ernest Shackleton's voyage on the Endurance, which left from the island of South Georgia on December the 5",
" 1914 to the Weddell Sea in Antarctica.",
... | [
"Sorry, but I don't see it:",
"1 - Where is the lactose in a diet based entirely on seal and penguin?",
"2 - We're discussing a crew of mostly british sailors. Very low incidence of lactose intolerance in that group to start with..."
] | [
"Sorry, but I don't see it:",
"1 - Where is the lactose in a diet based entirely on seal and penguin?",
"2 - We're discussing a crew of mostly british sailors. Very low incidence of lactose intolerance in that group to start with..."
] |
[
"What does \"Weak force violates Parity\" mean?"
] | [
false
] | By this I mean, what exactly does it do, and why is it a big deal. And as another question: Since it's really the Electroweak force, does electromagnetism break pairty too? | [
"Parity conservation is the idea that if you take the mirror image of a system, it should play out exactly the same except reversed. In other words nothing should have a 'left' or 'right' bias. ",
"But it turns out that when atoms that undergo beta decay are cooled down and put in a magnetic field, they emit more... | [
"First of all, let me explain spin. Particles have an intrinsic spin (it's analogous to the earth rotating around its axis, though in this case nothing is actually rotating). You can describe this spin by the direction its axis points. For particles like electrons, we say they're \"right-handed\" if the spin points... | [
"What are the implications of this? And do we know why it breaks parity?"
] |
[
"Is energy not conserved in our universe?"
] | [
false
] | This seems to say that energy is not conserved and it's fine?! I don't understand especially where the energy from photons go when they redshift. From the link .. particles like photons that move at or near the speed of light. The thing about photons is that they redshift, losing energy as space expands. If we keep tra... | [
"There are a couple entries on the ",
"FAQ",
" that you might want to read to start off with. I'll add some comments on your suggestions:",
"But couldn't it be so that the energy is simply absorbed into space",
"How is this any different than just saying energy isn't conserved?",
"or that the lost energy ... | [
"In general relativity, the energy component of the ",
"stress-energy tensor",
" is not conserved. Basically, it doesn't include gravitational potential energy. The ",
"stress-energy-momentum pseudotensor",
" does, but it depends on your coordinate system.",
"In short, the way people usually define energy... | [
"In my opinion, there are two meaningful ways to define energy in general relativity:",
"You can say that only matter has stress-energy. In GR, we always have a ",
" conservation law involving stress-energy, but that only leads to our usual notion of conservation of energy in flat spacetime, and that's ok. In c... |
[
"Can anyone explain why this hockey puck took this strange bounce?"
] | [
false
] | Video: In all of my years watching and playing hockey I have never seen anything like this happen, let alone at that very moment. | [
"It looks like although the puck had a translational movement heading towards the hockey net, it also had a rotational movement as well. I don't know how to put this in words, but the rotational movement was timed so the edge of the puck that hit the ice first was at just the right angle to put a force on the ice, ... | [
"Everything above is totally accurate and true. The only thing I might suggest that was missed is that perhaps there was a groove/edge on the ice from the keepers skates that the puck hit. I don't watch much hockey, but the ",
"cracks and grooves on a cricket pitch",
" play an amazingly important role to batter... | [
"The main reason this isn't seen in all knuckle-pucks in hockey is because of the low coefficient of friction of ice. There must be a deep groove on the ice for the puck to catch in order for it to convert the rotational motion to translational motion - otherwise it'll just slide on the ice.",
"Since this took pl... |
[
"How accurate is weather forecasting?"
] | [
false
] | I'm going camping in 2 weeks and the 14 day weather forecasts look great, but I have a hard time believing this could be predictable so far in advance. I'm going camping near Berlin, Germany. Does geographical location influence the predictability in any significant way and how accurate is weather forecasting in genera... | [
"I'm a meteorologist/atmospheric scientist, and I want to correct a few inaccuracies on your post:",
"A forecast for a mountain range in Colorado would not be as predictable as a forecast for, say, Missouri. (USA talk, I know, and I apologize for the reference)",
"I'm guessing you don't participate in WxChallen... | [
"Weather forecasts are based on a number of weather models that predict weather patterns ahead for x number of days. Generally, those models will agree up to a certain point; however, there are many factors that come in to play whether or not those models will play out. ",
"Take for instance, a hurricane coming... | [
"Very informative post. Thank you for clearing a few things up, the mountain range forecast is news to me; I would have far imaged a forecast for say eastern Colorado is easier than Missouri; however, not with the degree you are speaking of.",
"I know the %s I gave weren't maybe the best analysis to use, I was s... |
[
"Is there an approximate location, relative to our known universe, that is thought to have been where the singularity-point of the Big Bang existed?"
] | [
false
] | null | [
"The big bang didn't happen at a single point and expand outward. It was the rapid expansion of all space everywhere."
] | [
"No, it occurred everywhere."
] | [
"Read this 2005 Scientific American article, it will dispel most of your misconceptions about what the Big Bang is, was, isn't, or wasn't: ",
"http://www.mso.anu.edu.au/~charley/papers/LineweaverDavisSciAm.pdf"
] |
[
"Why do antibiotics cause rapid growth in animals?"
] | [
false
] | I read recently that antibiotics are given to farm animals to make them grow bigger, faster. Some people didn't believe me, so I looked it up again and confirmed it. What's happening in these situations? | [
"You're right, this is a real effect. And as of right now, we're not really sure how it works, though there are a few ideas. I'll quote verbatim from ",
"this paper",
":",
"At least four mechanisms have been proposed as explanations of antibiotic mediated growth enhancement: [1] inhibition of sub-clinical inf... | [
"Not sure. It's possible similar effects could be going on, we certainly know that the nature of the intestinal microbiota has a huge effect on metabolism, and anything that affects it will in turn affect the whole body.",
"Two things to keep in mind is that in animals, this is feedlot conditions where we want th... | [
"Oh, and third: the dose is different. Growth promotion in animals involves low, longterm antibiotic exposure, while a human taking them should only ever have a short-term antibiotic course, enough to cure an infection. "
] |
[
"AskScience AMA series: We are researchers in Quantum Computing and Quantum Information, here to answer your questions."
] | [
false
] | Hi everyone, we are BugeyeContinuum, mdreed, a_dog_named_bob, LuklearFusion, and qinfo, and we all work in Quantum Computing and/or Quantum Information. Please ask us anything! P.S.: Other QIP panelists are welcome to join in the fun, just post a short bio similar to the ones below, and I'll add it up here :). To get t... | [
"Questions one and three are in some sense the same, so I'll answer them here. There are many different systems people are trying to build quantum computers out of. Here's a list of some of the most popular ones. I'll do my best to explain each one, but I'm by no means an expert on them all. If other panelists ... | [
"Questions one and three are in some sense the same, so I'll answer them here. There are many different systems people are trying to build quantum computers out of. Here's a list of some of the most popular ones. I'll do my best to explain each one, but I'm by no means an expert on them all. If other panelists ... | [
"What do you think of D-Wave's claim to have a working quantum computer?",
"Which modality do you think will work first? Which do you think will work best in the long run?",
"Do you think topological quantum computing will be viable? Will it hold advantages over other systems?",
"A lot of people talk about th... |
[
"What are the random pangs of pain I feel sometimes?"
] | [
false
] | From time to time I might suddenly feel a random bit of pain somewhere in my body. The type of pain and location varies - could be in my chest/stomach/wrist/head/leg, physically anywhere, and ranges from short, sharp pains to a dull ache. It's never there for more than a brief period and then disappears. I'm not worrie... | [
"but then again, he wasn't asking for medical advice at all. Just asking about a physical body phenomena. Much like asking what that wet stuff is that comes out your eyes when you're sad. checking with a doctor is really lousy advice in that case. I too was curious about these pains. I've had them all my life, ... | [
"Ah yes. You have a quite remarkable condition. I believe I've heard it called \"",
" Syndrome\"."
] | [
"But there is no way for us to know, nor for ",
" to know, if the same thing is hurting him as is hurting you."
] |
[
"How did Rømer determine the speed of light?"
] | [
false
] | So i understand the basic principle: when the Earth is closer to Jupiter light from Io takes less time to travel. But how does the time between immersion and emergence of Io vary? | [
"Well, this one is a bit challenging, but it can be uncovered in layers.",
"The first thing you need is for Kepler to have come along and derived his equations, from which you know orbital parameters of Io around Jupiter, Jupiter around the Sun, and the Earth around the Sun. Let's assume you have that data, which... | [
"The t=500 is relative to the previous time; in other words, when observing from the far point of Earth's orbit, Io entered Jupiter's shadow and disappeared 500 seconds ",
" you would expect to see it do so, knowing the orbital parameters of all bodies involved. "
] | [
"I think ",
"/u/praecipula",
"'s notation is a bit off but the idea is correct. You observe when Io goes into and out of eclipse, thus giving you a time for when the eclipse happens. If you know the orbit of Io, Jupiter, and Earth precisely enough, then you can figure out when you expect Io to eclipse. If, when... |
[
"How does the air in a tunnel behave when a train passes through?"
] | [
false
] | I ride the subway to work every day and I've been wondering about this. How does air in a tunnel behave when a train goes through it? Does it get pushed forward or backward compared to the direction the train is moving? Compared to the train's velocity, how far does the displaced air mass get pushed? | [
"Cannot speak to the full science of this. However:",
"In the Eurotunnel, the size of the tunnels (there are 3 - one big one each way and one service tunnel in the center) was expanded multiple times in the design phase. The size of the trains was always expanded to basically completely fill the new tunnels. S... | [
"there will be high pressure air in front of the train, the air at the sides will be sucked backwards at a high velocty and there will be very tubulant air at the back of the train"
] | [
"Some more information can be found here:",
"http://www.brighthub.com/engineering/civil/articles/80592/p2/",
"There are piston relief ducts in the walls that connect the two train tunnels every 250m or so, and are about 2m in diameter.",
"Also a few good pictures here:",
"http://www.eurotunnelgroup.com/uk/t... |
[
"Do any animals other than humans practice birth control?"
] | [
false
] | Obviously they don't make condoms but do other primates pull out or have any observable knowledge of the connection between sex and reproduction? | [
"Gulls and other types of birds practice sequential egg laying as bet hedging against resource availability. Eggs, and eventually chicks, get pushed out of the nest in reverse order by older chicks when resources get depleted. Unlike primates, the birth control is practiced by the offspring, which is an interesting... | [
"There is a type of baboons, who eats the fruit of the plant Vitex doniana,\nwhich is kind of a anti-baby-pill.\nExspecially in the time from august to october.\nMaybe it's just a coincidence, but I guess you can't tell for sure, since you can't ask the baboons ;)",
"If you are interested, maybe you'll find an ar... | [
"[cite]",
", though without buying a copy from one of the journals, it's not going to be easy to find more info."
] |
[
"Why are we looking for the graviton if, according to general relativity, gravity isn't really a force?"
] | [
false
] | null | [
"It is true that in general relativity, gravity lacks a traditional potential except in the weak field limit. Whether or not you wish to call that geometric and 'not a force' or an extended definition of force is a matter of taste (as a consequence of its spin-2, simple quantum gravity frameworks have a tensor pote... | [
"According to general relativity, it should be possible to make ripples in the gravitational field called gravitational waves, very similar to electromagnetic waves. Just as electromagnetic waves come in discrete packets called photons due to quantum mechanics, gravitational waves should come in discrete packets ca... | [
"A particle is a quantum of excitation of a field. General Relativity is a field theory, any quantum gravity theory should have GR as a classical (non-quantum) limit (at least in a wide variety of circumstances) and so we expect it to be a theory with the same basic field content (plus maybe some others)."
] |
[
"what is the process for writing data on a cd and how do dvd players read the data?"
] | [
false
] | 'Computing' Sorry im 13 and my English is patchy at times. Thank you in advanced :) | [
"A CD has microscopic tracks consisting of tiny holes and flat areas. When the right kind of laser light is shined on a flat area, it is reflected back, but when it shines on one of the holes, it is not. A CD player works by shining a laser on the CD and keeping track of when the light is reflected back and when it... | [
"Instead of the layer of dye, a CD-RW contains a layer of material that can change between two different phases, crystalline (structured) or amorphous (unstructured). Think of it as water changing phases between liquid and solid (ice). This phase-change can be accomplished through heat delivered by the laser pulse.... | [
"They use blue lasers instead of red, shorter wavelength enables smaller grooves."
] |
[
"How do Human vaccine HIV trials work?"
] | [
false
] | How do researchers go about the human phase of testing vaccines work for fatal diseases? Who would ever intentionally expose themselves to HIV? Just saw that a . | [
"I thought the vaccine was ~31% effective?"
] | [
"\"chilloutdamnit\" is correct in that for trials such as these, cohorts of patients that are enrolled are generally in a group that is at high risk of getting infected. For HIV these groups are generally intravenous drug users or MSM (Men who have Sex with Men). these patients are immunized and then tracked over... | [
"These vaccines are administered groups of \"high risk\" individuals. In a famous failed trial in thailand, there was a double blind test in heroin addicted sex workers. One group was given placebo and the other was given vaccinations. Both groups received safe sex education and were discouraged from risky activiti... |
[
"Why are planetary orbits stable?"
] | [
false
] | Why do planets stay in orbit? From a systems perspective, where is the negative feedback to keep them "dialed in" when, say, a meteor hits, say, the earth, and adds force. Or when a meteor hits and increases the mass of the earth. Or when atmosphere is blown off and mass decreases. Or if everybody in China jumps at... | [
"Or if everybody in China jumps at the same time. Or a butterfly flaps its wings somewhere. In an unstable system - one without negative feedback - anything would be enough to knock a planet out of orbit, right?",
"Sure, if you add or subtract energy or momentum to the system you will change it to a different orb... | [
"Planetary orbits wobble a good amount, and while two-body orbital assumptions are fine for most things, you have to take gravity of other planets (ok mostly just Jupiter) when you want to get precise. ",
"Another way of looking at it: Any planets that weren't in stable orbits aren't around to get looked at 4 bil... | [
"First, of the things you mentioned all are very small forces compared to the mass of the Earth, and would be balanced out over time by other random forces. E.g., the asteroid that killed the dinosaurs is estimated to be 10km, with an energy of 4x10",
" J. If all this kinetic energy was converted into momentum,... |
[
"Does the Universe spin?"
] | [
false
] | Note: I am not a scientist. I have no degree and very little education, though I am working on that. I fell off the curve years ago and am playing catch-up. So...just about everything in our universe that we can perceive has spin..solo or in orbit..it makes circles, they being the most stable geometric shape. And most ... | [
"The universe has no reason to spin.",
"Celestial bodies spin because the force of gravity between any two celestial bodies is going to have a force at an angle. That is going to cause spin. ",
"To put that a different way, the chances of two orbital bodies interacting directly against each other (Ie the sum of... | [
"Completely agree with your answer but what if there is more than one universe?"
] | [
"Isn't the universe all of space and time? Isn't that like asking \"what if there is more than one everything\"?"
] |
[
"If the Strong Interaction were slightly different, would different types of particles exist?"
] | [
false
] | Or would particles not be able to exist at all? | [
"It'd have to be ",
" different. Everything having to do with hadronic physics arises from two facts: there are three colour charges and three colour anticharges, and gluons carry colour charge. In order to get different ",
" of particles, you'd have to change those fundamental truths."
] | [
"Well again, that depends on ",
" it's stronger/weaker on the atomic scale. For instance, one can well treat the binding of nuclei as the exchange of pions, and we could imagine some kind of world where pions have more or less mass than we measure them to have in our world. And maybe whatever changes to the mass ... | [
"What kind of differences are you imagining?"
] |
[
"Lots of meteors enter Earth's atmosphere every day, and I would think that some amount of space debris must be accumulating, even if it is just dust, so my question is how much accretion is happening, say in millimeters per millennium?"
] | [
false
] | null | [
"\"Estimates for the mass of material that falls on Earth each year range from 37,000-78,000 tons.\"",
" Meteors have an average density of ",
"3.36 g/cm³",
". Averaged over the Earth's 510,072,000 km² surface that's ",
", or 20-41 nm/millenium."
] | [
"According to ",
"http://en.wikipedia.org/wiki/Cosmic_dust",
", 40 000 tonnes of debris falls on Earth yearly.",
"If you spread that out to the full surface of the Earth (510.1 million square kilometers), you get 7.8 grams per square kilometer every year.",
"If we assumed the space dust has roughly the same... | [
"Yep. Over the lifetime of the Earth the average accretion rate is (radius of Earth)/(age of Earth), a whopping 1400 mm/millenium!"
] |
[
"What kind of event could severely change Earth's orbit or rotation speed?"
] | [
false
] | Could anything human-made cause this to happen? | [
"I believe it was due to the impact with a Mars sized planet that did this, creating the moon from the debris. "
] | [
"Rotation speed is changed with relative frequency on earth, though only by extremely small amounts and only through the most catastrophic of events. The one that comes to mind is the recent earthquake in Japan, where a day on earth ",
"became 1.8 microseconds longer.",
"Orbit is much more difficult. Suppose we... | [
"Would not the times the asteroid is in front of the earth balance out? I would think smashing the earth with giant asteroids every now and then would shift the earth's orbit more "
] |
[
"Why cant a ramjet transition to a scramjet?"
] | [
false
] | [deleted] | [
"Well, the issue is not exactly the inlet, which with a lot of effort could be made variable to either slow the airflow to subsonic or keep it supersonic. The issue is that supersonic and subsonic combustion is very different. In most modern turbojet, augmented turbojet, turbofan (low and high bypass), the velocity... | [
"A ramjet must slow down the supersonic inlet airflow to subsonic speeds. Cumbustion istself at supersonic speeds is very, very tricky, and part of the scramjet research. If you want to slow down the inlet airflow at say mach 5 to < mach 1, it would introduce so much drag, that you can't accelerate any further. A ... | [
"One professor of mine likened a scram jet as trying to light a candle in a hurricane. It's extremely difficult to do.",
"Another point you should take into account is the composition of the air. At those altitudes and airspeed, the temps, pressures, and compositions of the air are vastly different. Ratification ... |
[
"Do flightless birds have hollow bones like those that can actually fly?"
] | [
false
] | Also, if they are hollow, what benefit are they to these kinds of birds? If they aren't, were there previously flying versions of these birds before their wings were no longer hollow? | [
"The ancestor of all birds had hollow bones, but some birds have lost this trait (or at least partially lost it) to adapt to conditions other than flight, such as diving under water. So loons and grebes have solid bones to aide in diving under water for fishing. True flightless birds such as ostriches and penguins ... | [
"Dinosaurs closely related to birds, such as velociraptors, also had hollow bones, suggesting that hollow bones were a trait possessed by the common ancestor of birds and velociraptors. So it would be a good guess that flightless birds also have hollow bones."
] | [
"Turkeys have 'hollow' bones, as do chickens. I wouldn't call their bones hollow though, more like less dense. The compact tissue in most land animals is generally thicker than that of birds, while the cancellous tissue is far more dense in land animals than our aves friends."
] |
[
"Can people with Alzheimer's learn things or behaviours? Or would they forget them too?"
] | [
false
] | So for example it might be useful for someone with Alzheimer's to learn to write things down on a regular basis. But could they learn and remember the behaviour of writing things down if it's not something they've usually done before? | [
"People with Alzheimer's dementia are able to learn things through classical conditioning because the part of the brain that stores this information is unaffected by the disease. In theory you could use classical conditioning to get someone with Alzheimer's to write things down but they would have no idea why they'... | [
"In Alzheimer's dementia, higher order cognition and attention are affected the most. They also start have spotty memory gaps. This is a very frightening process when you think about their lived-in experience. What would be purpose of writing down \"toothpaste is empty\" when they would struggle to find their way t... | [
"What if it was as simple as writing down what they were doing throughout each day? So they could write things like \"had tuna sandwich for lunch\", \"finished off toothpaste-buy more\".\nSomething like that could help them avoid distress and confusion maybe?"
] |
[
"Apollo 15, the hammer and the feather - how do we explain what this proves?"
] | [
false
] | [deleted] | [
"But that's not exactly true, is it?",
"Yes, it's exactly true.",
"The force due to gravity exerted by two objects is based on the masses of both objects multiplied together. ",
"Correct. But objects with more mass also require more force to accelerate. So we have two things going on:",
"Force due to grav... | [
"We can, however, go further down the rabbit hole, and consider the fact that the moon will be accelerated slightly faster toward the hammer than toward the feather, so you're still somewhat correct, though the magnitude of the acceleration is so small as to be negligible.",
"This is the critical part. It isn't s... | [
"Thank you for this; I probably learned this as well at the same time, but had forgotten it. I appreciate your taking the time to spell it out for me. "
] |
[
"Is bipedalism still evolving?"
] | [
false
] | [deleted] | [
"Can you be more specific with your question?",
"All organisms are continuously evolving...that never stops. So bipedal species are, by definition, evolving.",
"If you're asking if other forms of locomotion may become dominant in large land organisms, I don't believe there is any evidence of that at this time.... | [
"I certainly didn't mean to suggest that bipedalism couldn't change in the distant future... only that there's no sign of it changing today."
] | [
"I don't think there would be any evidence for an \"end result\" in terms of evolutionary locomotion since mutations that would eventually lead to modes of locomotion are random?",
"That might sound confusing, but for example when life was restricted to the ocean there would have been no \"evidence\" that life wo... |
[
"Why don't batteries discharge when they are chained?"
] | [
false
] | [deleted] | [
"Electricity, for the most part, requires a complete closed circuit to work.",
"You can visualize this like water. Let's pretend you have two pumps (batteries) and you connect one to the other, but they are closed on the other ends. If you turn one on, no water moves because it has nowhere to go. But, if you conn... | [
"To put it another way: a battery is a chemical device which creates a voltage difference. The negative terminal is not 0V. All you can say for certain about the battery is that for each battery the + terminal is X volts above the - terminal. When you connect the + to the - terminal of another battery, the - of ... | [
"No. In the case of two batteries or two capacitors being connected in series, the result is no net current flow unless there is a complete circuit. The storage mechanism is irrelevant. "
] |
[
"Is dry ice dangerous, after in water?"
] | [
false
] | null | [
"A considerable risk here is that the carbon dioxide gas released by the sublimating dry ice will remain at a low level over the surface of the pool (it's denser than air). So you get in the water, breath at the surface, and potentially are inhaling very high levels of CO2. 1% concentrations can cause drowsiness, 7... | [
"How much dry ice? Is it still solid or has it all sublimated?"
] | [
"Pretty sure it has sublimated. "
] |
[
"Does ALL mass distort space-time? How and why does it do it?"
] | [
false
] | I find it strange that mass should distort space-time. Isn't mass in inherit property of matter? If it is, then why the distortion? I can see why LARGE masses would cause this, but small masses doing it makes no sense to me. Also, how and why does mass distort space-time? | [
"Why does it make more sense to you that large masses would do something completely different to small masses?",
"(Small masses have correspondingly small gravity)"
] | [
"I can see why LARGE masses would cause this, but small masses doing it makes no sense to me",
"Gravity is extremely weak, that's why. Also, remember that objects like the earth are made up of a multitude of tiny pieces. It stands to reason that the tiny parts collectively contribute to a strong gravitational fie... | [
"Because of the analogy that WifoutTeef posted. I guess it makes sense that small masses still affect space-time."
] |
[
"How can Radon be dangerous if it's a noble gas?"
] | [
false
] | I understand that it can be broken down from different radioactive elements, but how come it's still radioactive once it's a noble gas? I thought noble gasses didn't react with anything? | [
"There are two types of reactions at play here. Noble gases do not react ",
", that is to say that they don't easily form molecules with other atoms. On the other hand, radioactivity has to do with the stability of the atomic nucleus. The two don't have much to do with each other.",
"The radon atom has an unsta... | [
"As it is itself still radioactive, it continues ",
"breaking down into other elements",
" until it reaches something stable. In this case, it generally ends with isotopes of lead. Basically, consider radon to be ",
"breathable lead",
" with bonus particles (that themselves can also cause mutagenic damage).... | [
"Your sources seem to suggest the danger of Radon is connected to its radioactivity and not it’s decay products. The main danger of Radon is its radioactiveness, not the fact that half of it turns to lead after 20+ years."
] |
[
"If I inject some synthetic Epinephrine (Adrenalin), would I feel fear or have effects produced by fear as sweating, elevated heart rate, fast breating and belly pains?"
] | [
false
] | null | [
"I've been injected with a epipen as a safety precaution. It just feels like a hell of a caffeine high for a little while. Heart rate and mental alertness. "
] | [
"Houston Alexander (an MMA fighter) was tested in the TV series Sports Science. They tested his striking power based on a semi-relaxed state, his own 'pumped up and amped up' state, and then injected him with Adrenaline. ",
"His Adrenaline shots were not the most powerful, and it had a negative effect on his pe... | [
"Yes, you'd feel the effects of fear (increased heart rate etc), without being scared directly. Obviously, the scale of the effect will vary with the dosage, and it's not recommended that you try it out to see!"
] |
[
"Since the sense of taste and smell are linked, and dogs have an incredibly acute sense of smell, do they also have an incredibly acute sense of taste?"
] | [
false
] | null | [
"As a followup question... If true WHY DO THEY EAT SUCH NASTY THINGS?!?!?",
"My dog once ate a cricket in my room, threw it up and ate the vomit!"
] | [
"This is a legitimate question and certainly not anecdotal or layman speculation. This should not be down voted, however annoying the caps lock.",
"Living in a posh lifestyle as many modern humans do, your perspective is tainted. Go back a few hundred thousand years ago and you wouldn't find this so disgusting.",... | [
"Humans have more sensitive taste, but dogs can taste some things humans can't.",
"Some highlights from this article - ",
"http://www.psychologytoday.com/blog/canine-corner/201104/how-good-is-your-dogs-sense-taste",
"Humans win the sensitivity contest for taste, with around 9000 taste buds as compared with on... |
[
"It's Said That Fusion Power is Always 30 Years Away, But How Close Have We Actually Come to Fusion Power, and Have There Been any Recent Advances?"
] | [
false
] | As a followup, what are the biggest hurdles currently in the way of fusion power, and what's being done about them? | [
"As ",
"/u/iorgfeflkd",
" mentioned, we've always been 30 ",
" years away from fusion power. Without a massive shift in focus towards fusion, there won't be any grid-scale fusion power plants out there for a long time, but that's not to say we aren't making progress. ",
"Here",
" you can see that the trip... | [
"Not currently, but as archaic as it sounds boiling water to spin a turbine is actually a really efficient way to turn heat into motion, which we can then turn into electricity. "
] | [
"The proviso of that statement is that if we want it in 30 years, we'll have to pay for it now, and funding has been massively cut since about the 70s. ",
"The problem with fusion power",
" is that it requires an ",
" large investment to get an initial prototype working, and that hasn't been put forward. The... |
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