title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why does pigment UV-reactive pigment still \"pop\" more than \"normal\" color under standard white light?"
] | [
false
] | As a theatrical lighting/scenic designer and instructor, I have used UV lights and paints/makeups somewhat regularly. I have a good working knowledge of phosphorescence and the reasons why these specially designed materials show under UV lights while others do not glow. What I'm particularly interested in talking abo... | [
"Standard white light contains UV light in addition to visible light (take a look at the ",
"solar spectrum",
"). So florescent materials reflect visible light ",
" convert UV light to visible light under white light, while non-florescent materials only reflect visible light, so standard materials end up dark... | [
"Depends on what you mean by \"standard\" white light. Fluorescent lighting works by producing UV light and then passing it through a fluorescent coating on the surface to downshift the light into the visible range. Sunlight has a significant UV component as well. "
] | [
"Sorry for not clarifying. I planned to add \"incandescent\" after \"standard\" in my initial post and should have been more clear than that. Most traditional theatrical lamps have a color temp of 3000K (this can vary a bit, but we're usually in the 3000-3400K range) at full. As the industry is shifting more int... |
[
"How do you compare sound levels? A drop from 38.6dB to 24.7dB is not a 36% drop, right?"
] | [
false
] | On the box of a Geforce GTX 970 video card that has a better heatsink and fan than the stock version, it says it's "36% quieter". And in tiny print "Acoustic @ GPU 80c. ACX2.0: 24.7dB, Reference blower: 38.6dB. Noise - Up to 36% Quieter. This is one instance of marketing fail that actually could have gone in the other ... | [
"The rule of \"3 dB doubles the volume\" is not true. If we use ",
" as the measure of volume, then it is true. But as I explained, volume is typically associated to the amplitude (pressure), which has an extra factor of 2 in the formula. So if you double the amplitude, then the difference in decibels is",
"ΔD ... | [
"The decibel is a logarithmic unit that measures ratios of some field quantity, relative to some reference value. When we talk about the decibels of a sound wave, we usually mean the unit associated to a ",
" ratio, and the reference pressure is the typical threshold of human hearing (about 20 mPa in air or 1 mPa... | [
"Okay, I see we are talking about two slightly different (but related) questions. ",
"You are saying that if the pressure goes from p to 2p, then the change in SPL is +6 dB. I agree with that.",
"I was trying to say that if the sound source doubles, for example adding an identical sound source playing equally... |
[
"What prevents the intestines from tangling themselves like my headphone cords?"
] | [
false
] | Really, I've always wondered this. | [
"Dentist here. We concentrate on the teeth, but we do study the whole body in pretty gross detail.",
"The short answer to your question is that the intestines are attached to several different connective tissues, particularly mesentery and omentum. Mesentery is a very stretchy connective tissue that loosely holds... | [
"They can get tangled, and it is a very serious medical problem that if left untreated can kill a person. \"Luckily\" it is also exceedingly painful, so it rarely goes ignored. It's not exceedingly rare either.",
"As has already been mentioned, there are a variety of ways the body prevents this from happening, mo... | [
"On top of that, they can move around and get in places they're not supposed to be, like trapped in the omental bursa, which can then strangulate or obstruct the intestines. "
] |
[
"Need help poking holes in a perpetual motion argument"
] | [
false
] | I came across this paragraph on a perpetual motion machine building site, and it seems wrong, but I can't find the exact fault. What's that you say - perpetual motion is impossible? My, you're a difficult one to please. The electrons in the molecules of rock formations have been spinning steadily for millions of ye... | [
"Perpetual ",
" is perfectly possible in physics. An object moving through space, not being acted upon by any forces, will move for ever. The problem comes along when you try and use that motion to get energy to do something else, you end up slowing the thing down.",
"Also, electrons \"spinning\"? If they're re... | [
"Yes.",
"The wavefunction is an equation that describes the state of a system and its relationship to time. The mathematics of such an equation are extremely abstract; they have to be, because quantum mechanics does not permit us, as classical physics does, to go about our day blithely pretending that infinitely ... | [
"Electrons are not \"spinning\" around nuclei in the sense of a planetary orbit. That was an early and important theory called the ",
"Bohr Model",
" of the atom, long since discarded. Electrons are ",
" spread around the nucleus/nuclei of the atom/molecule, and the ground-state wavefunctions are generally ... |
[
"Vaccines"
] | [
false
] | Been a few years since science so excuse my incorrect references. People always say that vaccines are a safer way to introduce an antigen to the immune system because the antigen has been killed already. One of the very first experiments we learn about in biology is Pasteur's experiment where the parts of the DNA from ... | [
"Also, that was not Pasteur's experiment but Frederick Griffith's Transforming principle-\n",
"http://www.ncbi.nlm.nih.gov/books/NBK22104/"
] | [
"In addition to all of the points you made, I would add that, at least in the US, most (if not all...I think there was one on ",
"this",
" list) of the commercially available vaccines against bacterial agents are inactivated subunit vaccines rather than live attenuated, so that would really eliminate any hypoth... | [
"How does the transfer of genes between bacteria relate to vaccines?",
"To answer one part: no, we have many bacterial vaccines, e.g. pneumococcus, pertussis, tetanus, meningococcus, haemophilus, diphtheria."
] |
[
"For a reaction with a given reaction mechanism, is the activation energy a constant?"
] | [
false
] | I know that catalysts use a different reaction mechanism with a lower activation energy, but for a given mechanism, does the activation energy change with respect to temperature, pressure, or reactant concentration? | [
"In practice the energy required to overcome a barrier is the same for the same reaction path. Most of the factors you named will change the entropy of the system, change the average kinetic energy, or change the reaction path entirely. Those factors will have an impact on the rate of the reaction, however this a... | [
"Gibbs free energy is pressure dependent. ",
"dG = -S dT + V dP",
"In practice for liquids and solids you need large pressure changes to influence it, but it is still there. You can just usually assume that the change to the volume is so small that you can ignore it. ",
"But changing the pressure can influen... | [
"Yup the rate of reaction is exponentially proportional to the free energy of activation. The kinetic prefactor in a lot of transition state equations is actually related to the entropic components of the free energy. ",
"http://www.umich.edu/~elements/03chap/html/transition/"
] |
[
"What happens to a molecule when one of its constituent atoms undergoes radioactive decay?"
] | [
false
] | [deleted] | [
"It depends on the type of decay, and the molecule in question.",
"Alpha decay (the emission of a helium nucleus) is rather violent and will likely have enough reverberation to destroy the molecule. If the reverberation does not destroy the bonds then the molecule must still be able to share bonds between its ato... | [
"In minerals, the daughter isotope (what the original atom decayed into) is ",
" still stuck in the mineral, as it has atoms holding it in on every side. This is how we're able to radiometrically age date minerals like Zircon and Potassium Feldspar. We compare the amount of daughter isotopes that shouldn't have b... | [
"In all nuclear reactions (alpha, beta and gamma decay) the particle is emitted from the nucleus of the atom. Since the nucleus contains only protons and neutrons, for the nucleus to emit an electron, one of the neutrons must decay into a proton - electron pair."
] |
[
"What’s happening when cloths are bleached by the Sun?"
] | [
false
] | null | [
"Energized photons from the sun (likely in the UV spectrum) are spontaneously hitting the pigment molecules in the clothing, causing them to break apart. By breaking apart, they lose their color properties. Over time, enough pigment molecules are destroyed to cause the garment overall to lose its color."
] | [
"Tangent: the flags planted on the moon have likely all been bleached white by now, which has interesting cultural resonance for us..."
] | [
"Earth's surface temperature won't make any difference in photon energy. However, during winter the earth is tilted away from the sun, meaning more light gets filtered out through the atmosphere and less light reaches the surface than during the summer. So it would make a difference in that regard."
] |
[
"What's happening atomic level when I rub a balloon against my hair causing the balloon to become super staticky?"
] | [
false
] | null | [
"This may be an out of date model. See the link I provided (it's still really new research)"
] | [
"yeah, heck, I've taught exactly what you said. This is just the newest findings."
] | [
"Bits of charged material transfer from one object to the other",
"."
] |
[
"Is it ever practical to implement data structures of data structures (ex: a tree of trees) in computer science?"
] | [
false
] | [deleted] | [
"Technically every binary tree of sufficient size is a binary tree of binary trees.",
"Vectors of vectors and arrays of arrays are quite common."
] | [
"I cannot think of a practical application to the particular case of a binary tree of binary trees. But other cases of complex data structures, yes, of course.",
"Consider the filesystem: a directory or folder ",
" a data structure on itself, usually implemented as a hash table. Its elements are pointers to fil... | [
"It is actually practical.",
"I actually ran into this a few weeks back when I working a project in Django (a popular framework of Python). I was trying to receive values from a data set, and map it to a dictionary (Map, which is a key:value pairing). Well when I received the values, they were received as diction... |
[
"Can someone explain some of the chemistry involved in candy making? (Turkish Delight)"
] | [
false
] | See post about I am interested in knowing about the chemistry of candy making and specifically what makes the candy "set up" and how it expels moisture if it "sweats." Thanks! | [
"http://www.wikipedia.org/wiki/Starch_gelatinization",
"Making lokum is all about popping the cornstarch molecules like popcorn. Instead of oil, you're using water that makes its way in-between the starch molecules as the mixture cooks. The cooked starch appears (almost) colorless."
] | [
"HSMind is onto something. Turkish delight is a gel and an important element of the structure is starch molecules. ",
"Most turkish delight contains cornstarch. When boiled, the starch granules swell and burst, casting out their constituent starch molecules. Corn starch is over 60% Amylopectin (this is what make... | [
"Thanks everyone!"
] |
[
"How can we use one medication to treat multiple problems? Like using Humira to treat arthritis, plaque psoriasis, and ulcerative colitus?"
] | [
false
] | null | [
"Humira (adalimumab) is an anti-TNF antibody. Many inflammatory conditions with elevated TNF ranging from ulcerative colitis to certain forms of uveitis to Behcet's disease all use the inflammatory signalling molecule, TNF, to cause harm. This is not unique. Aspirin lowers fevers, help prevent myocardial infarction... | [
"Thanks this was informative. It just seems odd that I've noticed alot of cross use medications lately. "
] | [
"That's generally the case with drugs that end in -mab, adalimumab, ipilimumab, the mab stands for monoclonal antibody. Biologics like antibodies usually target a pathway or protein that mediates a pathway like TNFa, IL-1b, IL-21 etc. If that target is involved in \"inflammation\" then drugs that block it will help... |
[
"Do we have some idea why some amino acids are coded with a much higher redundancy than others in the genetic code?"
] | [
false
] | Looking at the table at I couldn't help but notice that some amino acids has far more redundancy in their coding than others - e.g. Tryptophan and Methionine has only one code while Arginine and Leucine has 6. Do we have some good theories on why that might be? Has substitutions of some of the amino acids generally mor... | [
"It has to do with redundancy. An amino acid with multiple codons coding for it can tolerate more possible mutations without changing into another amino acid. In some cases, you want the opposite, too. For example, if a stop was encoded by multiple codons, mutation to a stop would be more likely, which is bad since... | [
"Krelian is right. It's a difficult problem to study. There's a few hypotheses floating around.",
"Basically, some amino acids are more essential than others. For every possible mutation there exists a probability for loss-of-function. Substituting a histidine to a alanine carries a massive probability to loss of... | [
"There is also the presence of duons to be considered. Codons have now been shown to code for more than just amino acids. Thus, alternative codons for a single amino acid allow tolerance for mutation (silent mutations), as well as signalling in addition to coding."
] |
[
"Is distilled water so bad to drink?"
] | [
false
] | I've always heard that it was unhealthy, then more recently I read that it wasn't too harmful but may leach minerals from my body. How safe is distilled water? I have more than a gallon of it and I'll be thirsty this weekend! (I'm not sure the tap water here is safe.) | [
"Even without acid rain, rain is still not anywhere close to distilled water. Even without manmade pollution, there are still many other things in the air making even \"clean\" rainwater nothing like distilled water."
] | [
"You will get the minerals that most expensive bottles water claim to have in a mouthful of broccoli... (Ok, ",
" to prove a point)",
"ಠ_ಠ"
] | [
"I too have heard people make the claim that distilled water is not as healthy for us as tap water. For the most part, its bs.",
"As has already been pointed out here, distilled water is water that has been boiled and then had the water vapor recollected in a separate cooling vessel. Any impurities that were in... |
[
"Can the human body clear a HPV infection copletely?"
] | [
false
] | HPV can cause genital warts for example. Although these symptoms can vanish, I wanted to ask, whether the human body can get rid of HPV, so that it is not detectable anymore. On the internet some sources state that the virus can be cleared completely, while others state that it remains in the body for life. | [
"Your body can clear it over time and you should get checked yearly. Also, the HPV vaccine protects against over 9 strains that cause warts or ones that can rarely lead to cancers. Get the vaccine, it’ll help prevent other strains."
] | [
"Totally support getting the HPV vaccine! Doesn’t the currently licensed vaccine protect against 9 strains though, not 20+?"
] | [
"The vaccine is recommended for adults in the US. Up to 40 years old. LBGT in particular over 25."
] |
[
"Why is the Uncertainty Principle considered an intrinsic quality of matter rather than a limit of human perception?"
] | [
false
] | Been reading alot of popular physics books like Brief History of Time and have come across many references to Heisenberg's Uncertainty Principle (cannot detect both velocity + position of a particle, etc...) I get that, (simplistically, forgive me), shooting a photon at a particle to detect it would alter its position ... | [
"But why would the fact that WE can't percieve subatomic particles precisely imply that THE PARTICLES THEMSELVES have some innate quality of randomness, chaos, or lack exact positions and momentums? ",
"Because a model which treats a particle as having \"hidden variables\" which we are unable to percieve can't re... | [
"Simply: Because Particles are not correct. When we think of particles as little balls, it is incorrect, every particle is an oscillation in that particles field, so the Higgs Boson in an oscillation in the Higgs field, every electron is an oscillation in the Electron Field. ",
"Oscillations do not have distinct ... | [
"This is the correct answer. A theory involving \"hidden variables\" might be more intuitive, but experimental evidence suggests otherwise. ",
"To further address OPs questions:",
"Quantum systems can exist in states where they simply don't have a concrete position, momentum, etc. Instead, the system may hav... |
[
"What is the makeup of cooking smoke?"
] | [
false
] | [deleted] | [
"It's from the olive oil. Oils have what is called a ",
"smoke point",
" where the oil's carbon chains will degrade into soot which is essentially solid chunks of incompletely combusted carbon. Same kind of smoke you get from campfires and barbecues. You should probably cook at a lower temperature, or use a dif... | [
"The smoke point of oil will depend on the refining process. It might be worth trying a different brand of olive oil. Refined oils have higher smoke points and thus allow cooking at higher temperatures.",
"With that said, normal olive oil ",
" be fine and not smoke unless you're buying really cheap stuff. 4-6 m... | [
"As for the grease on the walls, Think of fastfood restruants, same principle. Yes it happens, and can happen fairly quickly"
] |
[
"Before the modern world, what caused the Earth's temperature to regularly vacillate 15 degrees (C)?"
] | [
false
] | [deleted] | [
"We're not entirely sure, but it appears to be broadly associated with tectonic activity. During periods of rifting and continent breakup, volcanic activity is increased and so more CO2 is released into the atmosphere. Once tectonic activity declines, so too do CO2 levels."
] | [
"Whenever there is a mountain range forming there is more weathering of rocks (more feldspar weathering). This results in burring CO2 and declining the atmospheric temperature.\nBut you can not compare the curve above with today's situation. The diagram shows that climate changes in the past took some millions of y... | [
"Why does it plateau at 25",
" C? That doesn't seem natural."
] |
[
"What is the use of a Van de Graaf Generator ?"
] | [
false
] | I just read about it in school. I think i understand is basic working and I know it is used to build up high voltages. But why do we need millions of volts ? | [
"Aside from cool science demonstrations, they are also used ",
"as particle accelerators",
"."
] | [
"In physics class at high school we used one to give ourselves high electric charges, to make our hair stand on end.",
"One school mate of mine was charged up in this way and the class ended. He assumed that it was all over and forgot the large number of volts he was carrying. I suggested he touch a grounded wate... | [
"This is exactly right. These can be used to study nuclear physics without a nuclear reactor when they have sufficient power."
] |
[
"If a plane or helicopter hovered stationary a mile above the earth would it rotate with the earth or would the earth rotate under it?"
] | [
false
] | [deleted] | [
"You needed to define what you mean by hover. What is the pilot remaining stationary relative to? "
] | [
"So if stationary it would rotate with the earth or the earth would rotate under it? I am a little confused by your answer."
] | [
"So if stationary it would rotate with the earth or the earth would rotate under it? I am a little confused by your answer."
] |
[
"It's my understanding that electrons can jump from one energy level to another but the radial distribution plot shows nodes where there is a ZERO % chance of an e- being found there. How do electrons pass that node when they change energy levels?"
] | [
false
] | null | [
"They don't \"pass\" anything. The point of saying that electrons jump is that it's a discrete transition, with no meaningful intermediate states. Besides, electrons in atoms don't have discrete locations, so they can't meaningfully be said to pass through nodes anyway."
] | [
"YES! Electrons, and in fact anything with a momentum was a wavelength. The wavelength of a baseball is in fact much smaller than the electron because it has a much greater momentum. This principle is how an electron microscope works.",
"De Broglie wavelength"
] | [
"Bound electrons in an atom act as standing waves, not particles. The plot you see is actually the square of magnitude of the wave function, which is a probability distribution. It's not that there exists a particle with a probability to be in any one place, but the electron is spread out over the whole atom. There... |
[
"Why don't markets wash the pesticides off their fruits for you?"
] | [
false
] | It makes no sense to me. Why wouldn't they make sure the food they sell is clean? Once it's in the market does it still need protection? | [
"It's not about the pests as much as shelf life. A lot of fruits will spoil faster once they've been washed, and the store does not want the produce to go bad before it sells. Check out ",
"these guidelines for proper washing of fruits",
"."
] | [
"Some fruits are washed, and in addition to that, they're coated with wax. ",
"http://www.fruitwaxcoating.com/fruitwax/",
"I used to get large deliveries of tomatoes, and sometimes almost all of them were coated with dirty wax from wax coated machinery. "
] | [
"Are there really that many pesticides on produce to wash off? Bruce Ames, inventor of the Ames test for mutagens, estimates the dose of carcinogenic pesticides consumed by the average American in a year to be less than the natural carcinogens present in a cup of coffee.",
"http://portal.acs.org:80/portal/acs/co... |
[
"If earth movies in epitical orbit how come temperature on earth remain nearly same?"
] | [
false
] | We know that earth revolves in eliptical orbit, so should the time when earth is near sun should be very hot but there are still winters in one hemisphere on earth and opposite should also be true for when earth is away. | [
"The difference is relatively small. 147 vs 152 million km. Compare that to the difference in insolation due to the angle of the sun and you'll find that the effect is minor. The southern hemisphere is in winter at apehelion (farthest) and summer at the closest, so experiences slightly larger temperature variations... | [
"We can quantify this by considering something called the ",
" of an orbit. If the eccentricity is zero, the orbit is circular, and if the eccentricity is 'just' less than 1 the orbit is as elliptical as possible.",
"The Earth's orbital eccentricity is 0.0167."
] | [
"Okay. So earth's orbit kinda circle but accurately its elliptical?"
] |
[
"Is eyesight a muscle that can be \"trained\"?"
] | [
false
] | Is your eyesight determined purely by genetic factors? Or can the amount of stimulation and use of your eyes when you are young train them to be stronger, or leave them to deteriorate? | [
"No. The eye is basically a lens, and if the focal length is messed up, your eyesight decreases. ",
"Here",
" is a diagram that displays shortsightedness vs. normal sight vs. farsightedness "
] | [
"There are some eye related conditions (such as lazy eye) that can be treated through muscle exercises. It doesn't improve vision or the lens, but it does improve how well a person can see."
] | [
"More interestingly, certain individuals (like myself) suffer from aphakia[1], which is the removal of the eye's natural lens. For people with aphakia, they must wear larger glasses and/or contacts to have somewhat normal vision. This is a clear example of why the eye does not behave like a trainable muscle--poorer... |
[
"Quick Question on Scientific Citations"
] | [
false
] | null | [
"Hmm, head over to ",
"/r/AskAcademia",
" and ask this there. I think that would be a much better place, ",
"Also, this website rocks for explaining how to cite things, especially weird sources. I used it all the time for APA formatting and the MLA section seems to be just as good.",
"http://owl.english.pur... | [
"It's one of those nebulous things that citation hasn't caught up with yet. I hope you can find your answer!"
] | [
"Thanks for the info, I'll post it over there and see if they know how",
"I've checked the owl, but the closest thing that I've found was just citing the entire thing as just a webpage. There is no author or journal or anything, just pure data. I would do it as just a page, but I'm pretty sure that there is a bet... |
[
"Why can't a fly get through those simple traps (a cup with a banana peel and holes poked in the top)?"
] | [
false
] | null | [
"While certain groups of insects are capable of latent learning (e.g. using landmarks for orientation and the like), they are completely incapable of insight or transfer learning. That is to say, in many situations, insects are unable to apply previous experience."
] | [
"Haha, I appreciate your interest :D",
"I'm broadly interested in applying molecular techniques to phylogenetic problems, including revisionary taxonomy and species delimitation. Currently, we're looking at the lichen feeding moth genus Lycomorpha. This particular group has been moved around quite a bit; no one r... | [
"Great answer! Also, I am extremely interested in hearing what it is that you study! I've never run into someone doing what your title reads!",
"EDIT: Added more exclamation marks."
] |
[
"Why do canned foods last so long?"
] | [
false
] | null | [
"Because they have (if performed correctly) been sterilized and do not contain spoiling bacteria. Due to the impermeable packaging, they also have no risk of being exposed to bacteria. That's not to say chemical degradation of the food isn't possible, but that's mostly just going to make it taste bland and/or nasty... | [
"but that's mostly just going to make it taste bland and/or nasty",
"A feat which is accomplished in large part by the canning process itself."
] | [
"To add to what laharre stated, canning also stops oxygen from getting to the food. This prevents the aerobic respiration that many microbes need to \"eat\" our food and cause it to spoil. Canning doesn't protect against everything, anaerobic bacteria such as botulinum can still be present in canned foods if they a... |
[
"What experimental evidence do we have supporting the Twin Paradox?"
] | [
false
] | null | [
"There isn't evidence of that literal scenario, because that thought experiment is really impractical to implement when you don't have technology capable of moving you at significant chunks of the speed of light. It is built on the predictions of special and general relativity, which, along with subjects based off ... | [
"Thanks for posting these lists. I'll definitely spend some time looking through them. I was mostly curious if there was direct evidence on the micro-scale, of particles moving at relativistic speeds, slowing them down to a lab frame, then estimating an effective time lag and showing it was consistent with the pred... | [
"One of the experiments listed is of muon decay. Basically we don't expect to see many at ground level because they decay so quickly, so we need time dilation to account for the number of muons we do observe."
] |
[
"What percentage of known atoms are formed by stars?"
] | [
false
] | [deleted] | [
"Shortly after the Big Bang (within a number of seconds to minutes), a process called ",
"Big Bang nucleosynthesis",
" created the earliest batch of atoms. These consisted of roughly 75% hydrogen, 25% helium (by mass), and traces of other elements. Essentially everything else was formed in a stellar process, th... | [
"Only",
" hydrogen, helium and small amounts of lithium and beryllium were formed during Big Bang.",
"\nThe rest all come from stars, whether from nucleosynthesis during stars' lives or during stars' deaths (supernovae), and cosmic rays.",
"Hydrogen is the ",
"most abundant",
" element in Universe, and to... | [
"There are a small handful of man-made elements as well, but as a fraction of the elements in the universe, it's 0%.",
"Of course, the number of atoms on Earth (as a fraction of the number of atoms in the universe) is also 0% (really, ~10",
"%, which is close enough to 0% for any reasonable person)."
] |
[
"Can someone explain the Unruh effect/radiation to me? How are virtual particles forced into existence if they are nothing but convenient mathematical models and don't actually exist?"
] | [
false
] | [deleted] | [
"I responded you in the other tread without realizing you had posted here as well, but anyway:",
"You're right, it doesn't. You should read about Bogoliubov transformations. In a nutshell, it means that two observers that are accelerated with respect to each other do not have to agree on what they perceive as the... | [
"I can't explain it better than the below. A uniformly accelerated reference frame is well described using \"Rindler coordinates\", so the \"Rindler observer\" mentioned is the one experiencing the Unruh thermal background of particles. ",
"From \"Spacetime and Geometry, an Introduction to General Relativity\" by... | [
"The whole point of relativity is that all observers' point of view are equally valid."
] |
[
"Are there dinosaur fossils to be found in the ocean? Or do bones deteriorate over time in saltwater?"
] | [
false
] | Most of the sea creature fossils that have been discovered are generally found on land, usually in a desert region, right? | [
"Hello!",
"There are a couple things going on here:",
"Dinosaurs were strictly terrestrial (at least until the birds came on the scene).",
"Global ocean levels were much higher when the dinosaurs ruled Earth; there were vast seas stretching over low lying areas, known as epeiric seas. So most of the sea crea... | [
"Awesome! Thanks for the info. You've absolutely answered my questions, especially the reason as to why there are more fossils in desert regions than in damper regions. They just have to covered up quickly by mud, sediment, etc. to truly be preserved. Thanks again!"
] | [
"Many of the fossils we find on land are actually of marine animals as you say, which means clearly they did not deteriorate in their initial ocean environment. Also deep ocean environments are low-energy and low-oxygen which is conducive to preserving materials."
] |
[
"Whats the deal with bacteriophages."
] | [
false
] | Is it just a bunch of sensationalist bs or could they help in a number of ways. Im referring to the video about them that takes place in Georgia (near russia) and why they haven't been researched more in the states, aside from the patent issues. | [
"While the video can be sensationalist, from all knowledge I have I can say that there is some credence to the institution in Georgia that was spearheading phage therapy. Definitely though, there are a few problems with phage therapy (for eg., immune response towards the phage from your immune system means you can ... | [
"Bacteriophages do indeed exist and they've been researched in the US since at least before the 1940s. In fact, the ",
"1969 Nobel prize in medicine",
" was awarded to scientists who studied bacteriophages.",
"I can't comment specifically on the research on using bacteriophages or human viruses for some sort... | [
"This is what I've said in the past. I think phage therapy definitely has potential, but also has a lot of problems. I'm not an expert in this at all though.",
"As langfan has said, your immune system attacks phages and other viruses pretty effectively, so safety concerns are pretty significant, and the virus pro... |
[
"Do fungi get infections/diseases?"
] | [
false
] | We know that plants and animals can get diseases/infections (e.g., from pathogenic bacteria, viruses, fungi, etc.), and bacteria themselves can also be infected by viruses. My question is whether fungi are susceptible to "infection" (however that may be defined), and if so, what the causal organisms (or non-organisms) ... | [
"Yup, there is a whole subclass of ",
"mycovirses",
", as a casual observer of the field it seems that if anything has a little extra energy to spare there will be a virus trying to steal it (including viruses that prey on other viruses). ",
"They are also locked in a war with bacteria, and we found many of o... | [
"if anything has a little extra energy to spare there will be a virus trying to steal it ",
"This sounds intriguing, can you explain a bit more? How does a virus \"steal spare energy\"? I feel like I kinda get what you're saying but if someone asked me what does it mean I'd be stumped.",
"I understand cells nee... | [
"Do viruses not attack life forms who don't have enough energy to spare? Or it's just that they kill their hosts and viruses don't survive?",
"The spare may be misleading. Many viruses do not kill their hosts, and killing a host can be the result of the virus not being well adapted to the host it is in. People wi... |
[
"Twin Paradox"
] | [
false
] | [deleted] | [
"For the best explanation of relativity ever given, read ",
"this"
] | [
"What happened to RRC?"
] | [
"I'm not sure you understood. The distance that you have traveled makes no difference in time dilation. For example, you could travel at a few thousand miles per hour, and take thousands of years to reach the nearest star, but the effects of time dilation would be pretty much non-existent since you weren't travel... |
[
"Where I live, most of our electricity is hydroelectric. If the turbines in the dam weren't there, where would all of that energy be going? Would the riverbed just be eroding that much faster?"
] | [
false
] | I'm thinking about all of the energy that comes from those dams - all the electric cars zooming around, all the ovens baking things, all the clothes dryers tumbling. What would all that energy be doing if the power plant hadn't harnessed it for us? | [
"Erosion is one factor, but energy would be dissipated in the turbulence of the water, heat generated by the friction in the water and also more evaporation. Greater evaporation transports more energy in the heat of enthalpy.",
"Have a look at the tail race of a hydro plant. It is very smooth and calm water. I... | [
"The energy is mainly potential energy which was stored up in a reservoir behind the dam. We block off a river with very little gravitational potential energy and \"store\" the energy in the lake. We then slowly transform that potential into kinetic energy which spins a turbine. If the dam weren't there, there woul... | [
"Owing to strong hydrogen bonds, water has a very high specific heat and enthalpy of vaporization. That is to say, water has to absorb a LOT of energy to change in temperature, and yet more to evaporate. This comes up in several areas of life. A small amount of sweat evaporating on the skin helps shed a lot of body... |
[
"Does a soda go flat faster if its on its side in the refrigerator as opposed to standing upright?"
] | [
false
] | [deleted] | [
"I suspect that the act of laying the bottle down on its edge (and all of the turbulence this introduces) may be what leads to the perception that it goes \"flat\" faster this way. ",
"Since bubbles tend to nucleate at the soda/plastic (or metal) interface, laying a bottle on its side lowers this interfacial area... | [
"I don't understand why posts that follow all of the subreddit guidelines (civil, on topic, scientific, free of anecdotes, free of ",
" speculation, and free of medical advice) get downvoted ",
". If you disagree, please expand the discussion!"
] | [
"I've noticed it a lot lately myself. It's not ",
" you it happens to. There's a rash of downvote lurkers in AskScience as of late. "
] |
[
"Is there a single word that describes something's position as uncertain, like how particles are?"
] | [
false
] | There's "entanglement" for entangled particles, "duality" for the way they act like waves and particles, and I could have sworn there was a similar word like the one I described in the title, but I just can't remember it. Sorry this isn't a very deep question, but I figured that if there is such a word, the people here... | [
"we usually just refer to it by Heisenberg Uncertainty Principle to my knowledge"
] | [
"Indeterminate.",
"Throughout the main body of his original 1927 paper, written in German, Heisenberg used the word, \"Unbestimmtheit\" (\"indeterminacy\"), to describe the basic theoretical principle. Only in the endnote did he switch to the word, \"Unsicherheit\" (\"uncertainty\"). When the English-language ver... | [
"Umm... Superposition?",
"Non-commuting properties?",
"Depends on exactly what you mean.",
"Position and momentum are just examples of non-commuting properties. "
] |
[
"Why aren't there that many heavy-element compounds?"
] | [
false
] | I under stand that there are a few like tungsten carbide but is there any that are all or mainly heavy elements? If not, why? | [
"There are plenty, it is just that many compounds are made of Carbon, Hydrogen, Oxygen, and a few other common elements. I guess a lot of the heavier elements are rare, either due to being hard to obtain or too radioactive so that there is hardly and left, so there aren't many. However if you mean in numbers, there... | [
"Not sure if this is what the OP is asking for, but there are also some transition metal cluster compounds that feature metal-metal bonds and are mostly metal by mass.",
"For example, ",
"tetrairidium dodecacarbonyl",
" is nearly 70% iridium."
] | [
"Umm, sure, but groups of metals don't really form compounds in the sense that you can point to a molecule of them. Mixtures of metals make alloys. The amount of different alloys you can make is nearly limitless since they are based on ratios of elements."
] |
[
"How can Venus have such a thick atmosphere while its hypothesized that Mars lost the majority of its atmosphere to solar wind?"
] | [
false
] | null | [
"The surface gravity of Venus is 8.87 m/s² while the surface gravity of Mars is 3.711 m/s². It's a lot easier for gas to reach escape velocity on Mars than on Venus.",
"Venus is also quite geologically active, producing more gas from the interior of the planet, while Mars is not very geologically active. "
] | [
"I wish we could see what the planets were like across all their geological history...we think of them as staying more or less the same, but it would really be something to see Venus during a resurfacing event, or Mars when Olympus Mons was active. "
] | [
"Hell, we don't even know when Earth really developed her continents, or what the early oceans looked like chemically, or how the planet behaved tectonically for the first two or three billion years. Or how the oceans got there in the first place. Each planet has surely had similar mysteries and secrets, buried by ... |
[
"How do scientists know when they find a fossil if it is a new species or just a significant mutation of an already discovered species, such as dwarfism?"
] | [
false
] | null | [
"Great question! Certainly we do have examples of pathological specimens, and some 'species' are likely deformed, juvenile, or paedomorphic examples of another documented species. Junior synonyms are quite common, and you're hitting on a bigger problem in paleontology: much of taxonomy is incredibly muddled. What w... | [
"Id imagine it might just be probability. Given how rare fossilisation is, itd be far more likely that another species is fossilised rather than the even less probable event of a rare mutated animal being fossilised. Although, any new species is a mutated version of another anyway so, in a way, it kinda is."
] | [
"They don´t really. Sometimes it can be obvious like findind a fossil that had to heads. But most times it isn´t. Eventually, they´d most likely find more fossils of the same animal and that would make it more likely that they are dealing with a new species."
] |
[
"When people get \"butterflies\" in their stomach, what is actually going on? And why does it only happen when they're nervous?"
] | [
false
] | [deleted] | [
"I would presume that your legs are much larger than your boner."
] | [
"adrenaline and other stress hormones cause vasodilation in your leg muscles (and other muscles, but mostly leg), which causes blood to flow away from other organs into the muscles and liver. this means blood will leave the vessels near your stomach. the butterflies feeling is due to blood going away from the stoma... | [
"then why don't I get butterflies when I get a boner?"
] |
[
"Do Black Holes Consume Dark Matter?"
] | [
false
] | If there is supposed to be a great deal more dark matter in the universe than matter we can actually see, should black holes be gaining mass at a greater rate than can't be accounted for with just regular matter? I guess a better question is do black holes interact with dark matter? Is there a way to know the mass of a... | [
"If dark matter crosses the event horizon, it cannot get back out, the same as with anything else.",
"Remember that the way we know dark matter exists is because we see the effects of its gravitational interactions, so we know explicitly that it is subject to gravitation (which would also follow on theoretical gr... | [
"The actual situation is that it interacts gravitationally with ordinary matter, not that it doesn't interact at all. If it didn't interact with ordinary matter at all, we could never know it was there! We first had evidence that it is there because if the matter we could see is all that there was, galaxies would... | [
"Short answer: No. A graviton, if it exists, would not have the right properties."
] |
[
"Ship Traveling the Speed of Light...."
] | [
false
] | So you're in a ship traveling the speed of light...It seems to me that you couldn't move laterally or forward, because you would be violating the whole nothing travels faster than c. But what prevents this phenomena from happening? Also, now that I think of it, would the rotational speed of electrons keep you from app... | [
"You already know that things with mass can't travel at exactly the speed of light, so I guess you wanted to imagine what it would be like to be in a ship traveling very very close to the speed of light (.9999999c, say). It's true that nothing can travel faster than the speed of light, but somewhat counterintuitiv... | [
"In a non-vacuum it also travels at the speed of light, but not necessarily in a straight line."
] | [
"You can't travel at the speed of light. If you're slightly below the speed of light, adding any amount of additional velocity in whatever direction always makes it such that your new speed is also below the speed of light.",
"If you're traveling at v and you add some additional speed u, your new speed is (u + v)... |
[
"Why do trans-Neptunian objects all seem to have orbits that are highly tilted?"
] | [
false
] | I noticed while doing some research that basically everything past Neptune (Pluto, Orcus, Haumea, Makemake, Eris, Quaoar, Sedna, etc.) all have orbits that are extremely tilted, and their tilts are all over the place, there's no pattern to them that I can see. Why is this? Is there some semi-exact radius from the sun i... | [
"This isn't unique to the Kuiper belt / trans-Neptunian objects. You see a similarly wide range of orbital inclinations for the ",
"Main Asteroid Belt",
" between Mars and Jupiter.",
"In both cases, this is largely the result of gravitational interactions and collisions with one another. Most of the material ... | [
"how Uranus was captured.",
"Uranus was not captured. It was formed with the rest of the solar system, and a later interaction tilted its rotation axis on its side. Both its composition compared to Neptune, as well as its orbital inclination compared to the other planets is much too similar for it to have formed ... | [
"hah! I just wrote a paper on ",
"Planet Nine",
" for my data science program. While this recently modeled planet can't account for all TNOs it does do a good job at explaining Sedna.",
"Orbits of Sedna, and five other unnamed TNOs all seem to 'shoot out' in the same direction ",
"like in this picture",
"... |
[
"Is the available ore for nuclear fuel in the earth’s crust decaying naturally, or does our enrichment set off that process?"
] | [
false
] | null | [
"Yes, it’s naturally decaying, very slowly."
] | [
"Thanks for the reply!",
"And so the enrichment and use as fuel speeds this decay by some huge order of magnitude by creating compounds with high reactivity, correct? So there’s no real “use it or lose it” element at work?"
] | [
"Both enrichment and burnup change the “effective half-life” of juclear fuel, yes."
] |
[
"About inertial frames of reference; how far does an object need to go to break free from the solar system?"
] | [
false
] | When I was very young, I wondered why I wouldn't go smashing through the back of a bus if I jumped while it was moving. I later learned about relative velocities, inertia, inertial frames of reference and the classic explanatory example of a ball dropping on the inside of a train moving at constant velocity. Now: we kn... | [
"What you're looking for is called ",
"the Sphere of Influence",
". You also want to look at ",
"Escape Velocity",
".",
"It's hard to answer your question without knowing your background in orbital mechanics... but more or less, there comes a point where you are no longer within the gravity well of the p... | [
"Once you are free from the Earth's pull (as free as a body can be), the primary sphere of influence is now the Sun (assuming that you are far away from any other planet or satellite).",
"Yes this is correct.",
"My question then is, are you also free of the Earth's orbit around the Sun, using the Sun as a fixed... | [
"\"Inertial frame of reference\" just means a reference frame that isn't accelerating. That is, if you imagine an accelerometer in that reference frame — a mass on a spring, say — it will read zero.",
"An object deep inside the gravitational field of another body is still moving inertially if it's freely falling.... |
[
"Could life have evolved on planets that we consider \"uninhabitable?\""
] | [
false
] | I saw the link about the light from the earth-like planet and it reminded me of a question I've had for a while. Whenever a story like this comes out, we are told that life could not exist on the planet because it is "uninhabitable," or more frequently that life could not exist on a planet without water. While I posses... | [
"While I possess basically only a high-school level knowledge of science, I'm left wondering if life forms could have evolved that wouldn't resemble the life forms we have on earth. ",
"Is it possible that on a different planet, some life form could have evolved that isn't carbon-based? ",
"You can read a whole... | [
"There are numerous examples of life outside of the oxygen-breathing, carbon-based life we take for granted. Many of these examples are different strains of archea, such as the ",
", which exists thousands of meters under the sea at temperatures of up to 113°C. These are still carbon-based, as all life on Earth i... | [
"Your premise is correct.",
"However, all life on earth is carbon-based and thus, while something else may exist, there are no examples. Furthermore, Pyrolobus fumarii is not bacteria but archea. The two groups are very different (its a bigger difference than comparing plants and animals!)."
] |
[
"My 11 year old son just asked; if you had a straw long enough to go from the bottom of the ocean up to space, would space's vacuum suck the water out of the ocean? My gut says yes, but what does science say?"
] | [
false
] | null | [
"Fun question and incredibly insightful for an 11 year old! ",
"But the answer is no. In order for the water to travel up a straw, the pressure outside of the straw would have to push downwards on the water harder than the pressure inside the straw is pushing downwards. ",
"When you suck on a straw in a drin... | [
"Even with a narrow and indestructible straw, with a perfect vacuum on one end and the other end in the bottom of the Marianas Trench, you still only get 34 feet, because the weight of the water can't push water up the straw. Only the air pushing down on the water can do that. It turns out that the diameter of the ... | [
"No - the vacuum at the top of the straw would be the same as the vacuum around it. Gravity keeps water on the surface of the earth despite the vacuum of space, and the water in the straw would experience the same tug of both gravity and vacuum as the water outside it."
] |
[
"[Astronomy] Why is Uranus' axial tilt given as 97.7° instead of 82.3°?"
] | [
false
] | Uranus is unusual because of it's large axial tilt, very close to being parallel with the orbital plane. So why is it stated as having an axial tilt that is greater than 90°? My guess is that they use the angle that assumes a prograde instead of retrograde rotation. However if that's the case, why is Venus listed as... | [
"You are right about the reason. Rotations have a direction, so we can assign not just an axis to a rotational motion, but a direction as well. This direction is given by the angular momentum vector. So we use a right-hand rule to determine the direction of the orbital and rotational angular momentum vectors; it... | [
"I did my PhD thesis on Uranus. ",
"Your points about both Uranus and Venus are up-to-date. In general the \"it got hit by something\" hypothesis has fallen out of favor in the past couple decades for both planets, since it requires a such a serious impact that the planets would have been expected to be obliterat... | [
"I am hoping a real planetary scientist weighs in, but I will describe my limited understanding of this (limited since this isn't my real field).",
"Reversing rotation in and of itself seems highly unlikely. This is a huge change in angular momentum, after all, and so it is difficult to imagine a process such th... |
[
"Why do soybeans curd? Why don't other legumes curd?"
] | [
false
] | [deleted] | [
"Curdling is a result of proteins being denatured by acid and clumping together. Soybeans have a significantly higher protein content than most legumes. If you evaporate enough water from other legume milks, you could increase the protein concentration enough to curdle. High protein legumes like split peas and lent... | [
"Thank you. I'll try to curdle some lentil milk after it has been reduced."
] | [
"What a cool question and answer. Thank you both!"
] |
[
"what happens when information is modified or lost when arriving at the brain?"
] | [
false
] | null | [
"So we can stimulate / knock out areas of the brain using transcranial magnetic stimulation (TMS) and this can impair processing. I'm not sure what you mean by \"where does the information go\" -- it's more like, adding distortions / noise to the signal until you can no longer recover it. "
] | [
"Speaking totally hypothetically, if you had a complete model of the brain and were able to record from all the neurons and knew how noise is added, then you might be able to reconstruct the original image, in the same way that it's possible to deblur an image or reverse some other type of image transformation. But... | [
"What does it mean to say that an image is modified by the brain? Isn't that the same as neurons firing in some unusual way? I'm not sure what you are trying to ask -- can we somehow read the brain activity of someone with brain damage and recover the original image? We can't really do that with a healthy person, s... |
[
"Why does our perception of heat change with the state of the medium we are surrounded in?"
] | [
false
] | Why does it seem colder if you get into a pool that's 70 degrees vs if you're standing outside when it's 70 degrees. Hypothesis: Is it because the density of atoms in the chlorinated water in a pool is much greater then the density of atoms in air? So since heat in my understanding is just the kinetic energy of the ato... | [
"You are basically right, but instead of thinking of the density of the actual molecules, think about energy density. A given volume of water has much greater energy density than the same volume of air. This is in part due to water's larger molecular weight than the average components of atmosphere, but also due to... | [
"Is thermal inertia a different way of saying specific heat? If so, could you say that water molecule's polarity contribute to its relatively high specific heat?"
] | [
"Specific heat refers to the heat capacity per unit mass. Thermal inertia means how much a given mass of whatever ",
" having it's temperature changed. Water has higher thermal inertia, so more way more energy is required to raise the temperature of a given amount as compared to something with less thermal inerti... |
[
"Dominance between the sperm and the egg?"
] | [
false
] | [deleted] | [
"No, there can be multiple forms (alleles) of any given gene, not just 2. However, any individual can only have 2 forms.",
"It is quite common for someone to have 2 of the same alleles for a given gene, we call this a homozygous individual (with respect to that particular gene. They are homozygous for that gene... | [
"You and skyline have already answered my questions for the most part, thanks. I edited something that I didn't really write clearly. When I mean 1/3, I mean 1/3 of my expressed genes.",
"Essentially, I've been under the impression that my child would have around 50% of my expressed genes expressed in him/hersel... | [
"Great questions. Reducing expression down to one allele is a process called ",
"imprinting",
". However, not all genes show ",
"monoallelic",
" expression as you suggest. Some genes are expressed in a biallelic fashion, where both alleles are expressed. This is distinct from codominance, as explained by ",... |
[
"TIL the dinosaur extinction asteroid theory was developed in the 80's. What were the extinction theories before this point?"
] | [
false
] | null | [
"Also surprised to learn the Chicxulub Crater was pinpointed as the dinosaur killer in just the early 90s."
] | [
"Hello,",
"This would be more appropriate for ",
"/r/AskScienceDiscussion",
".",
"Best."
] | [
"Thanks. Will do."
] |
[
"Is this a dumb idea to fix roads in wintery places?"
] | [
false
] | I live in WI. Our roads get decimated every winter largely because the frost penetrates deep in the ground causing frost heaves, cracks and holes. What if we spray foamed the first layer of road before adding the rebar, rock and pavement. Would that stop the frost penetration and lengthen the life of muh roads? | [
"It's not so much the water penetrating the pavement, but the water in the ground under the pavement freezing and causing the road to \"heave\" and bend more than intended, and crack. once a crack forms, water seeps in, freezes, makes it bigger, etc...",
"a more flexible road surface is the answer... old \"sand &... | [
"Going the other way and making a much less flexible surface also works. Some of the streets in Winnipeg, MB are done with a concrete mixture that's much more durable and less prone to potholes. The problem with it is that it's slippery as hell in the winter. They've tried a few different things to address that,... | [
"Dow Chemical doesnt think its a dumb idea. They say:",
"STYROFOAM Brand Insulation is also used to help reduce the potential for frost damage in these areas:",
"Airport runways, taxiways and embankments",
"Highway embankments",
"Under rail track, at-grade crossings, switching yards and other railroad facil... |
[
"If there are billion and billion of stars, why is it dark at night?"
] | [
false
] | With the assumption that light travels with no energy lose, with billion and billion of stars, shouldn't it be nice and bright here all the time ? | [
"http://en.wikipedia.org/wiki/Olbers\\'_paradox"
] | [
"Sure there are billions and billions of stars, but there are trillions and trillions of places where stars could be but they aren't."
] | [
"This addresses the question of whether or not the number of stars are infinite. OP is asking why, with billions of stars, is the sky still dark. For this question you only need to know that intensity drops with distance. As long as the stars are finite, the darkness of the night sky is relative to your average pos... |
[
"If all people have the same genome, what makes us different? And does this relate to gene expression?"
] | [
false
] | All people have the same genome (or very close to), but what makes us different from one another then? Random SNP's? If yes - why would a changed SNP not account for new type of gene? And how does this match up with gene expression? (i'm sorry if i'm asking absurdely) | [
"It might be helpful to start with a metaphor. Imagine a grocery store. This store is has all your major products such as ice cream, candy and pastries (I may have a slight sweet tooth). Different stores in the same chain are required to stock the same TYPES of products, and each store is required to have two and O... | [
"And are SNP's the same as Alleles?"
] | [
"We don't all have the same genome. It is true that all human genomes are very similar. In fact they are ",
"99.9% the same",
". This isn't so strange when you consider we have the same bone structure and organs. We use the same set of proteins for the same tasks, and build the same array of various cell ty... |
[
"Why is the solstice the beginning of winter and not the middle?"
] | [
false
] | If the solstice is the warmest/coldest time of the year, shouldn't it be in the middle of winter and summer, and likewise for the equinoxes and spring and fall? Instead winter started on the 21st. | [
"The earth, ocean and atmosphere do not heat instantly in response to increased solar radiation. That is to say, there is a lag between the maximum rate of energy input and the maximum temperature achieved.",
"Imagine a pot of water on the stove and slowly turning the flame up to maximum, and just as slowly turn... | [
"This is also true with the Hebrew calender. It is a lunar calender with leap months to stay relative to the solar calender, it begins/ends in autumn after the harvest."
] | [
"Except that in the Lunar calendars new year isn't especially close to Christmas and has little to do with the Sun. Even in locales that use a Solar calendar new year hasn't always been close to the winter solstice. During the period when the Julian calendar was used in England the year began around the spring equi... |
[
"I heard some people talking at the store and they said that gravity isn't really real. They said that instead, space is just curved. Please answer me this"
] | [
false
] | If that wasnt true then shouldn't a coin you drop from your hand get a little closer as it falls? | [
"If that wasnt true then shouldn't a coin you drop from your hand get a little closer as it falls?",
"It does, actually. It's just that you're so small relative to the mass of the earth that the effect is basically completely unnoticeable. If you weigh 70 kg, and a ball that weighs 1 kg is a meter away from you, ... | [
"The way I understand it (and I'm not a scientist) is that even when you are holding a coin motionless above the ground it is still moving through time.",
"The mass of the coin and the earth curve space-time such that their \"natural\" path will be to collide. You are exerting a force on the coin to divert it fr... | [
"Our modern understanding of gravity, derived from the theory of general relativity (GR), is that gravity is caused by the curvature of ",
" (not space). This in no way means \"gravity isn't really real\": gravity exists just as well, but may be understood geometrically instead of just as a force. GR gives us a v... |
[
"Where did the standard unit of 'one second' come from? Is it arbitrary?"
] | [
false
] | null | [
"Sorry, ",
" cs is stable so that's not accurate. You're thinking of how we use that particular Cesium isotope for measurement, but it doesn't relate to its half-life. iFLS is correct in this instance. :)",
"One source via absence, though it's generally pretty well known:\n",
"http://periodictable.com/Isoto... | [
"Sorry, ",
" cs is stable so that's not accurate. You're thinking of how we use that particular Cesium isotope for measurement, but it doesn't relate to its half-life. iFLS is correct in this instance. :)",
"One source via absence, though it's generally pretty well known:\n",
"http://periodictable.com/Isoto... | [
"To answer your second question: Yes, it is arbitrary.",
"As for where it came from: that would be a question for ",
"/r/askhistorians"
] |
[
"What is Stephen Hawking's concept of imaginary time?"
] | [
false
] | [deleted] | [
"He means \"people think that, and they're wrong, it's completely different\".",
"There is no \"imaginary time\" anywhere in physics. It's a math trick to relate quantum physics to thermodynamics, nothing more. It's a powerful and interesting trick however.",
"As for layman application, I don't think there is a... | [
"He means \"people think that, and they're wrong, it's completely different\".",
"There is no \"imaginary time\" anywhere in physics. It's a math trick to relate quantum physics to thermodynamics, nothing more. It's a powerful and interesting trick however.",
"As for layman application, I don't think there is a... | [
"There is no fundamental concept of imaginary time in physics, just a very interesting formal analogy between the \"generating functions\" for statistical and dynamical systems.",
"Basically, if you want to describe how a quantum system evolves in time, there is a \"basic brick\" which is a function from which yo... |
[
"Geneticists: is there any truth to what this redditor suggests about racial diversity?"
] | [
false
] | [deleted] | [
"Its all pretty much correct untill this ",
"It would seem, then, that the level of genetic differentiation among human populations is not especially small, and in fact is entirely adequate for race designation, particularly when coupled with consistent morphological differences.",
"Distribution of diversity do... | [
"The \"quip\" he is talking about comes from a famous paper by Richard Lewontin in 1972 titled \"The Apportionment of Human Diversity\". There, Lewontin makes the argument that most of genetic diversity (85%) is found within a sub-population. If I compare two random Europeans, and I compare a random European to a r... | [
"(Disclaimer: Not a geneticist. I studied physical anthropology. I'll give your question a go since no one else has.)",
"Much of what that Redditor said was true, but his/her conclusion was false. I was recently discussing ",
"a fairly similar topic",
" on another thread. Given the Redditor's name in the post... |
[
"Can you fall back asleep mid stage of sleep cycle if you've awoken during another stage."
] | [
false
] | I'm aware of sleep cycles, how they work and how long they last etc, but I'm very curious if it's possible for a human to wake up during a certain stage of the sleep cycle( say stage 3) and then instantly fall back into that same stage? Can that happen or do our stages always start back at 1? | [
"I know that one can fall directly in REM sleep, it's called \"SOREM\", Sleep Onset REM (which happens to me almost every night) and in some lucid dreams experiments that I did, I was able to fall back into a REM stage after waking up from it, this is called Dream Chaining I believe. As for other stages of sleep, I... | [
"Were the lucid dream experiments drug induced though? Also, isn't all REM \"sleep onset\"? I know that may be a stupid question but all REM is part of an onset sleep cycle. "
] | [
"No it was't drug induced. My undesrstanding of Sleep Onset REM is that you fall directly into that stage, without going through the others. In my case, I think all the years of inducing lucid dreams have messed up my sleep cycles. When I go to sleep, I always go through a REM stage immediately, for 15-20 minutes, ... |
[
"James Webb Space Telescope will be launched at the end of this year, how will it compare Hubble Space Telescope?"
] | [
false
] | I mean we already have some unbelievable imagery from the farthest of space, is new telescope a bigger deal in terms of what will become possible? | [
"Pretty pictures are a nice side effect but they are not the main purpose of telescopes.",
"Hubble is focused on visible light and ultraviolet with some infrared measurements. JWST focuses on infrared light with some visible light measurements. Different wavelength ranges have different science goals. In the over... | [
"From what I understand, here are some reasons why JWST will be different compared to Hubble.",
"-JWST has a light collecting area 6.25 times the size of Hubble. The mirror is much larger. More light collecting = brighter images of dim objects",
"JWST can 'see' far into the infrared spectrum. Hubble saw mostly ... | [
"It should see some exoplanets as distinct objects next to their stars, and it will do spectroscopy of the atmosphere of many exoplanets, giving us an idea of the chemical composition. It will take many pictures of distant galaxies."
] |
[
"Does heading the ball in soccer cause brain damage?"
] | [
false
] | My dad always insisted that I didn't head the ball. | [
"When you head the ball you lock your neck in place and use the hairline, right above your forehead (the hardest part on your head). Power comes from your abdomen- kind of like doing a sit up, combined with jumping towards the ball. Doing it like this will not cause brain damage. However, if you're using the bac... | [
"Try these",
". If you aren't behind an institutional paywall, ",
"/r/scholar",
" can help; I think some of them are freely accessible."
] | [
"As far as I understand the state of the art in the field, there is still a debate around the role that repeated subconcussive impacts (hits not hard enough to cause concussion) have on the long-term health of the brain. There seems to be strong evidence that repeated impacts (especially in children) can cause cogn... |
[
"Do brainwaves propagate into space?"
] | [
false
] | null | [
"No"
] | [
"Cool, can you elaborate?"
] | [
"Sorry I misread your original question -- I thought you just meant away from the skull, not into outer space. It's true that some EM signals make it out there (depending on their frequency and the weather for some of them). But brain waves, like radio and light, are subject to interference, reflection, refraction,... |
[
"How do a large ball and a small ball reach the ground at the same time??"
] | [
false
] | null | [
"The force of gravity depends on the mass of the object, but in the ",
" of the object, the mass cancels. The equation of motion is",
"ma = mg.",
"So you can divide both sides by m, and you just get a = g. All objects accelerate at the same rate, no matter what their masses are."
] | [
"Thank you for your reply!! But the weight is the overall force, right?? So a large object will reach the ground faster than a small one, even though the acceleration is the same, right?? (Neglecting air resistance)"
] | [
"So a large object will reach the ground faster than a small one, even though the acceleration is the same, right??",
"No."
] |
[
"[Biology] What is in the space between the lipid bilayer of our cellular membrane?"
] | [
false
] | null | [
"Only the hydrophobic tails. On these scales, the diffuse, smeared, wavy nature of atomic and molecular orbitals become substantial. When you consider an ",
"image",
" of a cross section of the bilayer, you have to realize that those balls and sticks aren't hard, solid objects like we consider: they're diffuse,... | [
"Fatty acid chains are roughly 18 carbon atoms long, and unsaturated hydrocarbon chain separation within a membrane is most frequently on the order of magnitude of just a few carbon diameters. "
] | [
"Are lipids that small?"
] |
[
"What is the importance of a Black Hole in our Universe and how reasonable is this theory?"
] | [
false
] | Having just stumbled upon the first ever actual photo of a Black Hole it got me thinking. I don't have any background in Science whatsoever, so forgive me if this is purely just rambling, but I find this discovery to be extremely fascinating. Here are some things I gathered: Also another thought I had, after watching t... | [
"The super-massive black hole in the centre of the galaxy only actually makes up a tiny fraction of the mass of the galaxy. It's like a million times the mass of the Sun, but the galaxy as a whole has like a ",
" times the mass of the Sun. Sag A* makes up like one millionth of the galaxy.",
"Really, all the sta... | [
"We have examples of two supermassive black holes orbiting each other. This typically happens when galaxies collide.",
"They tend to be close to the center because that's where matter accumulate the easiest and usually there is nothing else massive enough to make them move around much (binary supermassive black h... | [
"they're almost a double planet",
"They actually ",
" a double body, which is defined as two bodies whose center of mass lies outside the surface of either body.",
"The Earth-Moon system indeed classify as an \"almost-",
"/u/Astrowiki",
" -double body\", as their center of mass lies below the surface of t... |
[
"What are the factors that make a good takeoff/landing site in space launches?"
] | [
false
] | [deleted] | [
"Other factors include climate. The chances of overheating I'm sure are of some concern, but with rocket fuel burning and astronomical temperatures, I'm sure this is a much less important factor than things like snow and ice and cold temperatures.",
"I'm not sure that climate is taken into account too much - cert... | [
"Fuel.",
"Most satellites (any man-made objects, manned or not, orbiting the earth) are in orbit around the equator. It takes a massive amount of fuel to get to LEO and another massive amount of fuel to get higher. Sealaunch and Arianespace both launch near the equator. The US launches a lot from Florida, though ... | [
"Why Kazakhstan in front of Southern Italy/Spain/Portugal which are all closer to the Equator, are next to seas and members of the ESA?"
] |
[
"What is the most current, and widely accepted as true reason for the creation of the Universe/Big Bang?"
] | [
false
] | In simple terms, what theory is the most widely accepted as to the cause of the Big Bang or what created our known Universe? Or are their enough variations of ideas that not one is genuinely accepted as the correct one? | [
"Not everything has a cause",
". The big bang may well be something that happens because it can, but doesn't have a causal relationship. Right now I'd say a large portion of the physics community probably is in this camp. There are other big camps like brane cosmology which posits collisions between branes as the... | [
"Granted ",
" everything does. But some extreme circumstances in physics... don't. Particle decay is widely regarded to be a completely acausal process."
] | [
"Every scientific theory explains the events ",
" the big bang."
] |
[
"How do metal detectors work?"
] | [
false
] | To clarify, why does not all metal set off a detector? Such as zippers on jeans, or metal buttons? Do these detectors not detect certain kinds of metals, or do they just need at least a certain amount? | [
"A metal detector makes a varying magnetic field in an area using an electromagnet. Conductors such as metal will temporarily block magnetic fields from entering them due to the skin effect. The driver used to power the electromagnet will be affected due to the presence of large amounts of metal, since it has less ... | [
"I'm less familiar with the hobbyist detectors, but from an industrial metal detector perspective, I would not be terribly impressed with that. Naturally it depends on the size of the blade, but also the orientation of the blade relative to the detector coils.",
"In the industrial world, metal detectors are almo... | [
"It depends on the frequency that the scanner uses. If the scanner used 1MHz, the 0.2mm thick steel would hardly block the magnetic field at all. If the scanner used 100kHz, it would be undetectable. ",
"There are many hard and tough materials that are not conductive, such as ceramics. Most ceramics are brittle, ... |
[
"AskScience AMA Series: I'm Herman Pontzer, an anthropologist and professor at Duke University. My new book, BURN, shares new research on how the human metabolism really works so that we can finally improve health and manage weight. AMA!"
] | [
false
] | Hi Reddit! I'm Herman Pontzer, PhD, Associate Professor of Evolutionary Anthropology at Duke University and Associate Research Professor of Global Health at the Duke Global Health Institute. I conduct research on the human metabolism through studies with hunter-gatherer tribes like the Hadza in Africa. In my decade of ... | [
"We are swamped with high calorie processed food that is often hard to put down. Best advice, I think, is to stick to some basic principles: avoid ultraprocessed foods (anything with an ad campaign and long list of ingredients), try to increase protein and/or fiber intake which helps you feel full on fewer calories... | [
"With so many differing opinions and thoughts on health and weight loss, it is very difficult to separate what are known truths and developing theories. One quote that stuck with me from my undergraduate nutrition class at Chapel Hill went something like this:",
"\"There are no great diets, the only good diet is ... | [
"Nutrition science has taught us a lot, but I do think there’s value to an evolutionary perspective (for example, that our bodies don’t usually want to lose weight ; that we’re evolved to reproduce, not to have a beach ready bod) and to have a broader perspective of human diversity (not just industrialized societie... |
[
"Why is SO2 possible, but not S2O?"
] | [
false
] | [deleted] | [
"You are correct that sulfur and oxygen have the same valence electrons but that is only one part of the picture. the other is electronegativity. ",
"Oxygen is more electronegative than sulfur, so it has a stronger tendency to \"hold onto electrons\". In H2SO4, the oxygens are \"borrowing\" electrons from the cen... | [
"One problem with interchanging Sulfur and oxygen is that sulfur can break the octet rule as in H2SO4 in which it has six bonds around it, while oxygen can't. This is due to Sulfur's position in the periodic table. Its valence electrons are in the n=3 shell and it can utilize the 3d subshell to form additional bond... | [
"O has a valence shell of 2s2 2p4 and S a 3s2 3p4 configuration. Both have two upaired p's so should only want to form two bonds, right? Although there is some controversy about this, the way I learned it is that the 3p4 electrons can be promoted to the 3d orbital, which is only possible for Sulfur because the d or... |
[
"When drugs are tested for adverse effects, how do they prevent an initial outlier from halting future trials of the drug?"
] | [
false
] | Say they're testing a drug and the first study indicates that the drug causes sunburns, but in actuality the study just happened to coincide with the beginning of summer and many of the patients got sunburns at the same time. Wouldn't it be difficult to run another trial? I imagine people are very careful with first tr... | [
"Sample size. Clinical trial studies include enough patients/volunteers to account for this. At the end of the phase, adverse events are compiled. If only one patient has UV sensitivity out of a total of say 200 patients, it's usually assumed to be unrelated to the drug. "
] | [
"The first response is only correct if an adverse event is not serious. Clinical trials will usually have a data safety monitoring board (DSMB). This group of scientists is the only group of individuals that has access to unblinded information. They know for each study subject to which treatment arm they belong. I... | [
"All drugs with potential risk use the DSMB to protect the public and the company. The company sponsor will not know who was treated with the candidate drug or placebo until the end. Since many drugs end their lives during trials, the sooner the better. The motto is \"fail early, fail often.\" Safety is critical t... |
[
"Mars colony fantasies... Are any of these ideas feasible, AskScience?"
] | [
false
] | [deleted] | [
"Mars has almost no magnetosphere. The radiation would quickly eliminate a thicker atmosphere and damage complex life on the surface. There is a good chance Mars used to have a thick atmosphere and lots of water, however without a strong Magnetosphere, it was all cast off into space."
] | [
"There is 5um dust, 100x less atmosphere, no magnetosphere. ",
"WTF is wrong with people thinking we could warm a freaking planet and \"add atmosphere\". Sure just load up some CO2 canisters on a rocket ... people have no common sense."
] | [
"You could bioengineer microbes that pull Carbon, Oxygen, and Nitrogen from the rocks and soil. Honestly, some you don't even have to engineer, we already have them. This of course would take tens of thousands of years even if they were engineered for fast growth... and it wouldn't stick."
] |
[
"How do we know the temperature of the centre of the sun?"
] | [
false
] | null | [
"We know the amount of energy the Sun puts out, we know its mass, and we know its composition. We also know, both indirectly from the age of the Solar System (the Sun is too old to be producing energy through chemical reactions) and directly from the detection of ",
"neutrinos",
" from the Sun, that the energy ... | [
"Thank you for the clear consise answer :)"
] | [
"For a better explanation, can you explain how we know its composition and its age?"
] |
[
"Chicken pox?"
] | [
false
] | [deleted] | [
"Chicken pox usually presents with a rash over the entire body and goes away on it's own after it's fought off by your immune system. It lies dormant in your dorsal root ganglia and usually resurfaces later in life (50+ years) and presents as shingles. It is extremely unlikely that you've had chicken pox three tim... | [
"Why don't you provide some good/objective research then? I suspect you cannot do it"
] | [
"Why don't you provide some good/objective research then? I suspect you cannot do it"
] |
[
"Is anti-matter capable of nuclear fusion like ordinary matter is?"
] | [
false
] | [deleted] | [
"Yes. In almost every case, antimatter would have identical reactions to normal matter. "
] | [
"The charged current component of the weak interaction (mediated by W",
" bosons) treats quarks and antiquarks slightly differently. It may also do this with leptons but that hasn't been measured yet.",
"This manifests itself in neutral meson mixing, decay amplitudes and the interference between mixing and deca... | [
"In what cases does it behave differently? "
] |
[
"Why does my radio signal completely drop out when I strike an arc with a stick welder?"
] | [
false
] | When I'm at work, listening to tunes and working away having a good time I always get interrupted when my radio cuts out from the song and in to horrible static. It happens every time I strike an arc with my welder, so they must be related but I'm not sure how. Does the electricity from the welder interfere with the ra... | [
"It's interfering because your welder uses high frequency to initiate the arc rather than using a \"touch/lift\" method. With a touch/lift method only a few volts are passing through the electrode and when you lift it, your welder can sense a difference in voltage (due to the increased gap) and then initiates an ar... | [
"It's not simply high frequency, if that was the case it wouldn't be a problem (wifi is a high frequency, it does not effect FM), most radios have no problem rejecting HF. The problem is an arc welder creates sparks, sparks form ",
"spark gap transmitters",
", these are broad band transmitters, and that is the ... | [
"Your stick is essentially making up part of a ",
"spark-gap transmitter",
". A spark gap transmitter signal is dirty; it causes a lot of interference.",
"Another problem with the spark transmitter was a result of the shape of the waveform produced by each burst of electromagnetic radiation. These transmitter... |
[
"Friend posted this Instagram, brought up a debate about red shift and expansion?"
] | [
false
] | So today my friend posted this Taken on his cellphone. All of the stars appear red in the image, but looked like the normal white stars we always see with our naked eye looking up at them. I said that the phone made the stars in the image red because the stars are moving away from us. He said that I was wrong, and the ... | [
"You are both right: the colour of a star depends on its temperature, and objects that are farther away are more redshifted by the expansion of space. However, for the stars we can see with our eyes, that are in this galaxy, the redshift isn't really relevant. The red appearance of the stars in your photo likely ha... | [
"Others have already explained the reasons for the photograph's colors pretty well, so I'll focus on helping explain red shift.",
"As you probably know, light travels in waves. When the observer and the light source are traveling away from each other, the distance between the individual waves of that light would ... | [
"To put it simply, there isn't a great enough speed between you and the baseball for any significant shift to be perceivable. I know it can be hard to grasp just how fast stars' speeds away from us are, but suffice it to say that it would almost certainly be impossible to recreate it properly on Earth. Light waves ... |
[
"I'm a computer scientist and we like to generalize the human brain as being a massively parallel computer. Is this the prevailing view of modern neuroscience, or is the human brain more like a very fast, integrated system that efficiently retrieves memories?"
] | [
false
] | I'm really looking for recent publications that could help guide me in understanding what neuroscientists think of the brain and how cognition works. I saw the "just a very efficient memory" retriever on a couple different sites, but didn't know what to believe (or what scientific consensus was on this topic). | [
"The brain is massively parallel, treating it as a massively parallel computer is accurate, but somewhat mistaken. Although there are a few reasons I say this, the major one is that the massively parallel neural network is not the \"final level\" of computation in the brain. Within neurons, there are many processes... | [
"Given how little we know about how the brain works, it might be easier to start with how various computational models get the brain wrong.",
"Massively parallel - like a GPU: In a GPU, all of the small processors have the same architecture, and generally cannot work sequentially because they don't branch very we... | [
"I didn't go into it, but the microscopic events within neurons have profound roles on their activity. While it is true that Hodgkin-Huxley model neurons can reproduce much of the functionality of actual neurons, like orientation selectivity (similar to edge detection) and even ",
"episodic memory",
", they sti... |
[
"Does the mass lost by the Sun from fusion affect the orbits of the planets? How much more mass did the Sun have 4.5 billion years ago when the Earth formed?"
] | [
false
] | null | [
"It's a very insignificant mass decrease, and any orbital effects would be completely overshadowed by interactions between planets.",
"If you approximate the Sun as having constant luminosity (it's actually grown by a bit over its lifetime) then ",
"it has lost about 100 Earth masses",
" due to fusion, or abo... | [
"Doubt it. Fusion burns a few billion kilos ",
". Halley's Comet, for example, is a couple hundred trillion kilos. So that means that every ~10,000 seconds ( ~3 hours) the Sun would have to eat something the size of Halley's Comet. This simply doesn't occur. It's actually very difficult for the Sun to gain mass, ... | [
"It seems like the sun has probably accreted more mass by swallowing comets and the like than it has lost by fusion, is that correct?"
] |
[
"Is it possible to create a bell large enough, that when struck, it will ring at a frequency below standard human hearing (~20Hz?)"
] | [
false
] | Would there always be harmonics in the audible range that would sound like a bell reverberation, or could you actually make it all sub-audible (aside from the sound of the clapper hitting the bell). | [
"When you're striking it, you're making it vibrate in a bunch of different modes and there would always be some in the audible range, though they don't have to be loud. But you could avoid the audible overtones if you only vibrated the bell in a certain way, e.g. by resonance"
] | [
"fyi - guessing and speculation is typically frowned upon in this subreddit."
] | [
"fyi - guessing and speculation is typically frowned upon in this subreddit."
] |
[
"Is magnetism between two objects affected by the medium it passes through?"
] | [
false
] | I don't have much of a background in electricity and magnetism so I'm not exactly sure how to word this, but I'll try to be as precise as I can in my example to get my point across. I have a phone dock in my car that is magnetized. It comes with a piece of metal that you can either stick to the back of your phone with ... | [
"Yes, the ",
"permeability",
" (not to be confused with permitivity, as I did whilst trying to cite myself) affects it. For most materials it's approximately the same as a vacuum, but Iron is 200,000 more permeable to magnetic flux."
] | [
"No worries, magnetism is complicated, and there're so many concepts with names you might never guess."
] | [
"Firstly, I would not try and develop too much intuition around \"photons are the force carriers of the electromagnetic force\". It doesn't really mean what you're thinking it means. ",
"Regardless a solid material is not solid all the way down. It's made of a bunch of atom in a, usually, orderly arrangement. ... |
[
"Why is inflammation due to injury considered a bad thing?"
] | [
false
] | Everything I've read (on the Internet, admittedly) says inflammation serves several purposes, most importantly beginning the healing process for whatever is wrong. Why does it seem like everyone always recommends taking an NSAID for injuries to reduce inflammation? | [
"Inflammation, like any defensive mechanism, is subject to a variety of tradeoffs.",
"Very roughly speaking, no inflammation → no impairment (like swelling and pain), but also no healing. Lots of inflammation → lots of impairment, but also lots of healing.",
"The actual amount of inflammation we experience is d... | [
"If excessive pressure builds up after injury due to swelling it can result in impaired blood flow to the affected tissue. This is known as compartment syndrome. ",
"Organs and muscles are organised into compartments and fascia forms the walls of the compartments. After injury, blood or fluid may build up after i... | [
"Well, because our body tends to overdo it. Inflammation is good, without it we wont heal or be able to fight pathogens. But it is only good in the correct amount, any excess leading to autoimmune disorders or scarring"
] |
[
"Why does the apparent frequency due to a Doppler shift depend on whether the source or the detector is moving? Wouldn't the relative motion be the same?"
] | [
false
] | The equations for determining the apparent frequency are different depending on whether the source is moving, or the detector is moving. This seems really strange to me, as the perceived motion from the frame of reference of either the emitter or observer would be the same for the same speeds. The only thing I can thin... | [
"They have different motion ",
" - in the case of sound, the air."
] | [
"Sorry. Wrong answer above. Of course it's directional. The frequency, f, being defined as the frequency at the source, means that the source has to be the emitter of the frequency. You can swap them around only if you take the shifted frequency observed at the detector as the new source. An example would be i... | [
"Waves in the water hit a static object once a second. You get in a boat and drive into the waves. They now hit your boat twice a second. The frequency has doubled due to the doppler shift. Your boat carries a wave generator. When the boat is at rest the wave peaks are one second apart. When your boat moves the wav... |
[
"Harleys with aftermarket mufflers can be extremely loud. Some riders claim that it's a safety feature and \"loud pipes save lives\". Is there any evidence to support or refute this claim?"
] | [
false
] | [deleted] | [
"http://minnesota.publicradio.org/display/web/2007/05/29/loud_pipes_save_lives_or_risk_rights",
"The article is leaning towards \"no\" ... ",
"Next time you see someone with loud pipies, check to see if they're wearing a proper helmet, armored jacket, gloves, boots and pants. They're probably not.",
"I'm an a... | [
"Yeah, I won't deny that they might alert someone who didn't see you coming. ",
"Although, I also do wonder about the distraction they cause. Might they actually ",
"? I've been startled by loud pipes before, we all have.",
"Conclusive data would really help here."
] | [
"I also do wonder about the distraction they cause.",
"There's also an indirect problem: if you've been woken up at 5 AM by a loud bike, you'll be tired and less alert at the wheel."
] |
[
"Why do some materials, such as the porcelain from spark plugs, break glass easier than others?"
] | [
false
] | I've watched videos where tiny pieces of porcelain from spark plugs completely destroy a car window with little effort, and many multi tools offer a carbide tip that can break them just as easily. So what makes them better than other materials? | [
"Glass is a hard material. Most materials can't scratch it. And toughened glass has an outside layer that is actually tightly compressed. (This is done by cooling the glass down quickly, so the outside forms a fixed shell before the inside cools down and contracts.)",
"In order to break toughened glass, you need ... | [
"Porcelain, according to a potter I know, is a mix of silicates and corundum. After vitrification, the former is what's known as glass, and the latter is a key ingredient in sapphires and rubies. On the Mohs scale, sapphires are just one step below diamonds. Basically, a material at some level on the Mohs scale can... | [
"You need a material that doesn't compress much. Steel is relatively soft in this regard, though it is stronger than ceramics in many ways. A small impact with a broken spark plug exerts a higher pressure than even a hardy swing with a hammer."
] |
[
"Are some \"irrational\" numbers rational in other bases?"
] | [
false
] | This is more AskMath but I thought someone here could help. First, I may need an explanation of how decimals in other bases work in general. I started thinking about binary, and how decimals should work there. I assumed the following (binary on the left, base 10 on the right): And so forth. However, aren't there many d... | [
"You can have a rational number that terminates in one base but which repeats forever in another. In a base-3 system 1/3 (in base-10) terminates as 0.1 but in binary 1/3 is a repeating decimal, just as it is in base-10 (0.333333333.....).",
"But a rational number is rational in any base (i.e. can be expressed as ... | [
"You can use a base-pi system which makes pi easy to represent. It will be represented as 10. The same goes for any irrational number. ",
"However, the ease of representation has nothing to do with whether or not the number is irrational. Pi will always be irrational no matter how it is represented. Irrationa... | [
"Doesn't this make working in base 2 really difficult?",
"Indeed it does—and ",
"people have died as a result",
". One-tenth is a non-terminating expression in binary, and the cumulative error introduced by measuring time in one-tenth-of-a-second increments in Patriot missile guidance software led to a failur... |
[
"Can anyone explain the relationship between electricity and magnetism more intuitively?"
] | [
false
] | [deleted] | [
"Getting at the concept intuitively is a little tricky; in some ways it really is just easier to attack the maths on this!",
"You don't really need to think about what's going on at a quantum or atomic level; the salient points are really just as well understood as a classical field theory.",
"The basic gist of... | [
"Nice explanation. This might help to. If you just consider electrostatics as in coulomb attraction, you will find some interesting simple solutions in electrostatics but as charges start moving suddenly everything changes. This is as you (OP) said due to relativistic effects such as length contraction which create... | [
"Try drawing and playing with vector diagrams of magnetic, electric feilds and electron motion. Then try to explain it by another vector field of the other types. Later add time variations and slowly build up too stupid levels of complexity and you can do it by diagrams and probably mathematically too at that point... |
[
"Does the sun itself cause aging due to gamma waves?"
] | [
false
] | null | [
"No, that isn't the case."
] | [
"Gamma rays don't penetrate the Earth's atmosphere. Aging is a biological process, not a radiative one."
] | [
"Oh, okay. Thanks!"
] |
[
"Do all fragments leave an explosion with the same velocity?"
] | [
false
] | [deleted] | [
"All elements of the explosive would have about the same amount of energy imparted to them. Smaller pieces form due to seams/defects in the material that will cause them to shatter under the extreme pressure, this breaking takes some of the energy originally imparted to those pieces. The smaller bits also have a mu... | [
"You are assuming that there are equal numbers of 'small' and 'large' pieces. If I have 2 halves of the explosive that will go in opposite directions; on one side I get 3 large pieces of shrapnel, and on the other I get 18 small pieces. all pieces ",
" to have the same velocity for the sum of the total momentum o... | [
"You are assuming that there are equal numbers of 'small' and 'large' pieces. If I have 2 halves of the explosive that will go in opposite directions; on one side I get 3 large pieces of shrapnel, and on the other I get 18 small pieces. all pieces ",
" to have the same velocity for the sum of the total momentum o... |
[
"Is there a theoretical limit to how deadly a poison can be?"
] | [
false
] | I was reading a little about sarin in light of the Syrian situation and the allegations of its use, and I was wondering if there is a limit to how small a dose of poison you can use before there just isn't enough to affect enough of the body to cause death? | [
"Yes, the upper bound for a toxin is a lethal dose of one molecule."
] | [
"D'y'know what's great? Resinferatoxin is spicier than Capsaicin"
] | [
"I believe poison is much too general of a term. There are so many mechanisms that could lead to death that there are most certainly not enough chemicals in nature that could trigger them all. Also if there is no time limit on the effects of a poison, ie it does not have to cause immediate death, then the list coul... |
[
"When a liquid is poured into another liquid, which is likelier to splash out?"
] | [
true
] | [deleted] | [
"I was been said that it's because the hydratation of the acid is an exothermic process that can lead to spraying, and the heat is better controlled if the acid is slowly poured in water than vice versa."
] | [
"Think of it from a classical physics point of view:",
"You have liquid A, that you are pouring down into B. The act of pouring it would give it a fair amount of downward momentum. This means that not only would it have the energy required to displace liquid B back up (action, reaction) but it also means it would... | [
"I was taught in chemistry that its always the pool that splashes. We were told to always pour acid into water so that if anything splashes, it'll be the water!"
] |
[
"What is the wavelength or color of two overlapping laser beams?"
] | [
false
] | If two different wavelength lasers beams were collinear, what would the color of the combination be on a white surface? Is it possible to make white light out of two different colors? | [
"The two colors would simply be overlapping spatially. Filters down the line could separate the two wavelengths, they do not combine to form a third unique wavelength. There are cases where you can get a 3rd unique color as a result but it requires interaction with a material (this is called \"wavelength mixing\")... | [
"Everyone agrees that the distinction is important. This discussion is about the presumed meaning of \"white\" in NeodymiumCandy's original question. In common usage, and in technical usage relating to color, the meaning of white is \"any spectrum that produces the perceptual sensation of white.\" I would say it... | [
"If you were to shine a red laser pointer and a blue laser pointer onto the same spot of a white piece of paper, the result would be the same as combining red light and blue light, so you'd brain would see a purplish type color. ",
"You can never get white light out of only ",
" colors. White light is defined ... |
[
"What would happen if you received a blood transfusion of a blood type different than your own?"
] | [
false
] | null | [
"It depends on the combination of blood types. If you are type AB, nothing much will happen. If you are type A and receive B blood, or type O and receive any type but O, you sill experience destruction of the transfused rbcs (",
"hemolysis",
"), due to antibody recognition of ABO markers on the foreign cells.... | [
"They're thought to be a response to pathogens like viruses spreading from person to person and carrying some component of membrane protein with them, such that individuals who created an antibody response to foreign ABO markers had more success fighting off infections. ",
"wiki explanation here",
", ",
"jou... | [
"They are not necessarily antibodies looking for blood, but a defense system looking for bodies that do not match their own. The cells have a marker, depending on the blood, that lets the white blood cells know that they are native. Any cells without those markers are seen as foreign bodies, and therefore to be des... |
[
"Is there a reason for the hexagonal pattern on the doors of microwaves?"
] | [
false
] | Or is it just better if we don’t see what’s in there 100% clearly? | [
"It's made of metal and it stops the microwaves getting out while still letting you look inside. The wavelength of the microwaves is much longer than the small holes, so the screen is opaque to them.",
"A hexagonal pattern of circular holes will minimise the area of metal required, improving optical visibility an... | [
"No, the wavelength is the important thing.",
"Electromagnetic waves don't have an amplitude in space itself, but in the fields. They don't wave \"up and down\" in space. It's the direction of fields at a point in space that would be moving up and down."
] | [
"The electric and magnetic fields are both what we call vector fields. At every point in space, you associate its own 3D vector (you can think of it as an arrow, for these purposes) which has a magnitude and points in a certain direction. (Actually, it's two vectors per point in space, one for electric and other fo... |
[
"Where do all the protons go when a neutron star is formed? Or is a better question where did all the neutrons come from?"
] | [
false
] | So starts consist of hydrogen/helium and on up, nuclear fusing its heart out, literally in the case of a supernova. After the big boom, there is a neutron star left behind. Since all the atoms that were in the start prior to the super nova contain protons and neutrons, how can there be only neutrons left? Where did ... | [
"The star consists of atoms, which contain electrons, protons, and neutrons. At the high density and pressure involved in neutron star formation, you get the reaction",
"proton+electron --> neutron + neutrino",
"This is where the protons and electrons go. ",
"You can learn more about neutron stars (including... | [
"Neutrinos only interact via the weak force (and gravity, but that's irrelevant), which doesn't create such bound states."
] | [
"See what I'm replying to:",
"Why wouldn't protons or electrons bind with neutrinos first",
"I am pointing outnthatnthe weak force doesn't create neutrino-proton or neutrino-electron bound states. Neutrons don't even enter into this exchange."
] |
[
"How would one go about testing the speed of a processor outside of a computer?"
] | [
false
] | Is it possible to have just a processor and do a speed test without having to install it into the computer? This is in because I am doing a three year long research program at my High School on graphene and its conductivity compared to silicon in processors. Thanks! | [
"In order to test any processor, you will need to install it into a computer of some sort. The processor can't work on its own.",
"Also, where on earth are you going to find a Graphene-based computer?"
] | [
"TLDR: Here is a brief primer on the relevant issues in computer architecture, but I don't have an easy way for you to address your project at a high-school level.",
"I'm not really the best authority on computer architecture, but I can shed some light on this. You may need to just read up on flip-flops and logi... | [
"GHz is an absolutely horrible measure of processing power. The clock rate (\"GHz\") is an pretty arbitrary rate that is determined by an external oscillator and really isn't an indicator of how powerful a processor is. The reason why we have processors at different clock rates and why it is believed to equal perfo... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.