title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why is it whenever I make a root beer float, giant soap like bubbles appear?"
] | [
false
] | [deleted] | [
"Great question! Have you ever seen what happens when mentos is dropped into a coke? Its the same principle (but usually less messy)! Little air bubbles on the surface (of the ice cream/mentos) act as nucleation sites where CO2 that's dissolved in your root beer rapidly congregate. Water-soluble ingredients in the ... | [
"The reason that you get big, soapy-looking bubbles is because of the thickening ingredients that are used in most ice cream. Typically, you'll find vegetable gums and other thickeners listed among the ingredients. Traditional ice cream formulas contain milk, cream, sugar, and flavorings, and they make less foam."
... | [
"This being ",
"/r/askscience",
", I did do a quick google search for academic papers on foam formation in ice-cream floats, but surprisingly, I came up empty. Vegetable gums are commonly used for stabilizing foam in foods, though.",
"If you want to go more in-depth on this subject, try a search for \"food fo... |
[
"Could an animal evolve to live in space?"
] | [
false
] | Besides humans in spacesuits. Could an animal evolve to travel through space, like the Space Whale in Futurama? | [
"You may be interested in the ",
"Tardigrade",
":",
"In September 2007, tardigrades were taken into low Earth orbit on the FOTON-M3 mission and for 10 days were exposed to the vacuum of space. After they were returned to Earth, it was discovered that many of them survived and laid eggs that hatched normally.[... | [
"I thought photosynthesis involved using light to break down the CO2, in space it seems that the lack of anything to breakdown would mean photosynthesis would be unnecessary. "
] | [
"Yeah. You are absolutely right. Complete brain-fart there on my part...."
] |
[
"Does the immune system attack bacteriophages even though they don't pose a threat to human cells?"
] | [
false
] | null | [
"It's both. They exist in a symbiosis state with our immune system and mostly reside in the GI tract as microbiome. ",
"However they can leave the GI tract by transcytosis and enter the blood and other organs in the body. But since they can't infect human cells or eukaryotic cells, the immune system do not active... | [
"They do get phagocytosied as I mentioned in my previous reply. Here's a quote from the first paper: ",
"Phagocytosis by immune cells within the liver and spleen seem to be the major process of bacteriophage neutralization within the human body [26,78,80,104,106,107,108]. One should note that phagocytosis allows ... | [
"So the immune system don't bother touching them? I thought the immune system clears blood of debris, such as cell debris, bacteria and whatever else?"
] |
[
"Why can't we see the Andromeda Galaxy?"
] | [
false
] | [deleted] | [
"Lucky you, here the other day I think I saw the sun"
] | [
"In a perfectly clear sky with no light pollution you can clearly see the core of Andromeda as a fuzzy smudge. The visible core is smaller than the moon. The outer part of the galaxy is too faint for the naked eye, and you will only be able to capture the full galaxy with a decent telescope and a long exposure."
] | [
"Padua. It's not really the pollution, it's the atrocious weather."
] |
[
"How harmful is hydraulic fracturing fluid?"
] | [
false
] | [deleted] | [
"Something that is important to realize is that toxicity depends on concentration so lets say that 5000 gallons of chemicals were dumped 20 miles up stream so that means it will be diluted in millions of gallons of water that means that at worst you could see a few parts per million ... resulting in those chemical... | [
"The videos of people being able to light their water on fire isn't from the hydrofrac fluid itself, it's from gas escaping from it's reservoir due to the fractures that are created from hydrofracing. ",
"It can be more dangerous in drier areas where the aquifer is smaller and they tend to be more isolated, so th... | [
"Thank you, this is exactly the answer I was expecting. People around here are absolutely freaking out over all of this. There are videos online about people being able to light their water on fire, but nothing has come out yet from people near this incident."
] |
[
"Can one neuron within the human brain have several types of neurotransmitters that binds to it? For instance, can a neuron that usually allows binding by GABA neurotransmitters also allow binding from other types of neurotransmitters, such as NDMA, DA, 5-HT, etc?"
] | [
false
] | null | [
"Yes. Neurons can have, for instance, both excitatory and inhibitory inputs, mostly mediated through glutamate and GABA"
] | [
"There are a large number of examples. In the cerebral cortex, all of them have GABA and glutamate receptors, and generally multiple different types of each. "
] | [
"Exactly. I'm not sure if your example exists (may or may not, I don't know), but heres one that is fairly common: Cholinergic fibers and adrenergic fibers typically have heteroreceptors for each other in that cholinergic fibers often have presynaptic alpha2-receptors, and adrenergic fibers often have muscarinic re... |
[
"What was the diet of early humans? How did they know what foods were safe to eat?"
] | [
false
] | What did they survive off of on a daily basis and beyond that how did they know what plants were safe to eat? | [
"Australian Aborigines would take the food and hold it against their body for certain amount of time. If there was no negative reaction they would move down the list.",
"Source: Malcolm Douglas"
] | [
"And they would have an ",
" amount of knowledge of safe edible plants culturally passed on from a time since even before they were humans. Most primates actually ",
" their children what is food and what is not.",
"Coming in contact with completely new potential foodstuff would have been a very rare occasion... | [
"It minimises the risk though. Eventually someone would have to eat it. If they die then they would make a note that that ones not so good for eating. Trial and error, but the knowledge gets passed on until they had enough options to keep fed and taking stupid risks on unknown plants would not be necissary unless t... |
[
"Redditors: what are some things you wish they would have mentioned in health class that they didn't?"
] | [
false
] | null | [
"I really wish they had mentioned more in sex education than vanilla. It would have helped a bunch to know that my kinks were fairly normal. "
] | [
"If you can reformulate your question to one of a scientific nature it may be allowed. Personally I think it should be banned as a random survey with no aspect of the scientific method."
] | [
"Sometimes the vagina can be too tight for penetration"
] |
[
"Does every living thing need to have DNA?"
] | [
false
] | With the exception of RNA based "organisms" (like viruses, since they're not really considered alive). Does everything need to have DNA to be alive? Basically if we went to Europa and discovered life, would it be possible for the life that evolved on that planet to be DNA-less? Do we have DNA-less living organisms here... | [
"1) It could well be that extraterrestrial life isn't DNA based. But for evolution to happen you need something that encodes information and for complex life you need evolution. So you would need some sort of information storing molecule. Scientist have created artificial DNA alternatives in the lab, so we know tha... | [
"Based on the definitions of life, all currently known living things have DNA (or RNA that gets converted to DNA at some point of it's life cycle).",
"Now, prions are infectious proteins that can infect, propagate and spread without DNA by converting host proteins into infectious proteins. But, I would not define... | [
"Some viruses. It is still debatable if they count as alive, but I side with the alive crowd.",
"They travel around as encapsulated RNA and infect a cell. Once inside, they are copied as DNA and then encode RNA versions of themselves."
] |
[
"Have flying insects evolved ways to combat spider webs?"
] | [
false
] | I noticed a duel of sorts between a moth and a spider just now where I was certain the moth was doomed as it flew into the section where a spider had firmly set up its web, but as it flapped its wings so quickly it tore apart the web, and even sent the spider fleeing. I don't know if this in itself was an adaption to w... | [
"Yes! There are wasps which specialise in preying on spiders. Some even go so far as to kill the spider, then use their web to line their nests. I tried to find something interesting on the ",
" genus, but they're such a bunch of trouble to ID that there's not much written."
] | [
"According to the ",
"wikipedia article!",
" about them, the sting is ",
"And that's what a human experiences."
] | [
"Tarantula Hawk. Their sting is so painful it paralyzes tarantulas so they can lay their eggs. Also when they hatch they avoid eating the vital organs so the spider stays alive longer. "
] |
[
"Can children learn musical instruments like languages?"
] | [
false
] | [deleted] | [
"Language is a specialised function of the brain with dedicated areas. These have probably derived from evolutionary processes because language serves a selective function. In other words, we are predisposed to learn languages, especially during the first years of life.",
"Playing music is different, as we probab... | [
"Music is practice. The more you practice, the more proficient you are. Thus, anyone can jam a violin…with enough practice. ",
"Some people will have a knack, but those people still need to practice. The person who practices daily for a year, will be better than the person with a knack."
] | [
"Like many areas its a combination of both natural ability and practice/effort. Some people are very talented but don't put in effort, others are willing to try hard but lack abilities (such as rhythm or pitch awareness). The outstanding ones are those willing to put in the effort who also have at least some raw ... |
[
"If caffeine antagonizes all adenosine receptors, how can consumption increase activity (A2B receptor)?"
] | [
false
] | First of, I am a biomedical student with a great interest in neuroscience and my knowledge is most likely incomplete/imperfect so please correct any mistakes I make: There are 4 adenosine receptors, 3 of which are significantly present in the brain; A1, A2A and A2B. Caffeine antagonizes all of these receptors but only ... | [
"The most likely answer is what you're suspecting,",
"Is this all just all a matter of which system is stronger or am I seriously missing something here.",
"If you look more closely at the pharmacokinetics of caffeine receptor stimulation/molecular degradation you will most likely find a bottleneck that keeps ... | [
"You also need to consider the relative prevalence of each receptor and the strength of each one's effects; there are common and uncommon receptors, and some give stronger responses than others. It would be very, very odd if the final tally somehow ended up with the effects balancing out perfectly.",
"Once you l... | [
"Agreed. I know this isn't very closely related to your question OP, but here's a chart ",
"showing how different Xanthines",
" with VERY similar structures have completely differing effects on biological activity. "
] |
[
"When did the most recent common ancestor of coronaviruses and influenza viruses exist?"
] | [
false
] | In some quarters comparisons between covid and the flu have been taken so far as to claim that covid a flu. Such claims seem patently incorrect, as the viruses belong to different taxa - but just how wrong is it? Would it be comparable to claiming that cats are dogs, or more akin to equating cats and nematodes? I'm ass... | [
"Coronaviruses and influenza viruses are both members of the ",
"Riboviria",
":",
"RNA viruses that use cognate RNA-dependent RNA polymerases (RdRps) for replication. These viruses are highly diverse genetically, infect a wide range of prokaryotic and eukaryotic hosts, and comprise three classes of Baltimore ... | [
"Some viruses probably started as mobile elements from organisms’ genomes, that acquired ways to spread to different organisms. Other viruses probably started as full organisms that gradually become increasingly parasitic, and lost non-essential elements. (Possibly some arose via abiogenesis as free-living mRNA ele... | [
"Complicated inferences from the distribution of organisms the various groups of viruses infect."
] |
[
"Why are some viruses deadly?"
] | [
false
] | Doesn't it make more sense, evolutionary-wise, for a virus to not kill its host? Wouldn't it be able to spread much better over a longer period of time? | [
"Indeed, ebola can cause death within 10 days which makes it a bad propagator of itself (especially in our more sanitary civilized conditions, read ",
" it is a good book); but ebola isn't contagious in the air like a common cold, and needs to kill you to try to spread. It is a trade off, but since said viruses e... | [
"Viruses interact with the cellular machinery of your body. This is why a virus that is deadly to humans may not affect other animals and vice versa. Really deadly viruses are often viruses that have recently jumped species, or new strains combining a virus that infects one species and a virus that infects another.... | [
"You're absolutely right. A virus that kills its host quickly is a crappy virus. If you look at all the most successful viruses, none of them are all that lethal - the common cold, the flu, herpes, chickenpox, HIV, etc. They all have the common trait of being severe enough to cause symptoms, but not dangerous enoug... |
[
"Do mosquitoes do anything positive for nature?"
] | [
false
] | Because i think they should be eradicated, But i know they probably do something good | [
"Well, like with anything, they have a place in their ecosystem. There are things that eat them, and things that compete with them for resources etc, so removing all the mosquitoes could have unpredictable effects on other species in the area.",
" my understanding is that there are lots of species of mosquito in ... | [
"Here you are presenting a ",
": That organisms have a role in nature. Living things aren't here for something, they just are here because the conditions on our environment have led to the development of such creatures.",
"You don't need a role in nature to be part of it. Let me ask you back: ",
" As you can ... | [
"Thanks"
] |
[
"Why does the sun shine in a \"star\" shape?"
] | [
false
] | is what Im talking about. Is it an opticak effect. Is it caused by the lens, the atmosphere, the human eye, the star itself. What goes on here? Thanks smart people. | [
"This is caused by the movable aperture blades in a camera lens. ",
"http://www.cameratechnica.com/2011/02/24/how-to-create-and-avoid-starburst-highlights/"
] | [
"thank you. so do video cameras work the same way?"
] | [
"Most video cameras use the same kind of 'bladed' set-up to restrict aperture, so yes, it creates the same star shapes in video as in photographs."
] |
[
"How can medication cause side effects that counter effect each other?"
] | [
false
] | For example, side effects such as tiredness and fatigue are caused by a medication, but also insomnia or even increased energy. "How is it that medication causes side effects that are opposites of each other?" may be a more appropriate question. | [
"When determining side effects for drugs, pharmaceutical companies do a study in which half the people get the drug and half the people get a placebo. If there's a significant difference in the different side effects reported in each group, the company must list that as a side effect, either as a requirement to the... | [
"This makes sense as to why they'd list them as side effects. Thanks. Further to this though, I personally have experienced the side effects I listed above, i.e. tiredness & fatigue but unable to sleep at the same time, or shortly after attempting to sleep. Is there an explanation to this? Maybe a biological one? "... | [
"I'm not qualified enough to answer that question. Perhaps someone else can jump in. "
] |
[
"Is visible light damaging to your eyes and vision, or just UV?"
] | [
false
] | I got some high-powered LED's which emit light within the visible spectrum, and I am wondering, can I do damage with these, or is it just light in the UV range which is actually dangerous? | [
"Any light can damage your eyes. But UV has 2 special problems. First, it's higher energy than visible light, and the kind of energy level that organic compounds just love to absorb and subsequently disintegrate or denaturize. Of course, the compounds in your eyes love to absorb visible light as well, that's somewh... | [
"Yes, it can. There are 2 aspects of light that matter for damaging something:",
"see EM spectrum",
"UV light has a short wavelength, and so it has higher energy photons than visible light. UV photons have enough energy to break bonds in DNA, which is why UV can damage tissue and cause cancer. Meanwhile visible... | [
"Yes! And even worse, your pupils won’t contract as much either. And this is a bad thing even if you don’t stare into the sun; UV reflected from the environment (esp. water and snow) and scattered by the atmosphere is enough to cause harm over long term in sunny climates. Cheap sunglasses can be actively harmful to... |
[
"What is currently the most dangerous medical threat to humanity?"
] | [
false
] | After reading about prion diseases for a while I want to curl up in he fetal position and cry. It's hard to seperate mass media hysteria from scientific knowledge - is there currently a disease or condition that could threaten all of humanity? | [
"You must've been reading my comments in that beer thread!",
"Prion diseases are not a dangerous medical threat. So don't worry about them.",
"There are many emerging infectious diseases that scientists worry about. The worst diseases tend to be those that are only recently infectious in humans. Keep in mind... | [
"Dengue hemorrhagic fever (DHF) is considered to be one of the most dangerous emerging diseases. While it hasn't reached pandemic levels, it certainly has the potential to do so in the future. There are several reasons for this:",
"Dengue is mainly vectored by two different types of mosquitoes, Aedes albopictus a... | [
"What do you think about the potential of ",
"Totally Drug Resistant Tuberculosis (TDR-TB)",
"?"
] |
[
"Could loud sounds that cannot be heard by the human ear, from being too low or two high, still cause damage to one's ears?"
] | [
false
] | null | [
"Certainly. What we hear as sound is actually vibration caused by kinetic energy. Our hearing range is from 20-20,000 hz but just because we can't hear it doesn't mean it's not there. High energy soundwaves can do more than destroy a person's ear drums, it can kill you.",
"",
"https://www.extremetech.com/extre... | [
"I'm not sure about sounds above our hearing range but there's been a bit of research into the effects of infrasound (sounds below our hearing range) and prolonged exposure may cause some level of hearing loss but that's not confirmed. There have been some studies showing that infrasound can cause negative emotions... | [
"yes. Sound has two properties of interest in terms of causing damage to the human ear. The first is frequency which determines the pitch of the sound. Humans can hear sounds with a frequency of between 20hz and 20000hz. loud noises in these areas damage the hair cells inside the cone shaped channel in your inner e... |
[
"Has the Copernican Principle been debunked?"
] | [
false
] | [deleted] | [
"Well, none of those links are working for me, but the cosmological principle has certainly not been debunked (or if it has, it's happened in the last few minutes which is why neither I nor anybody else in my department has heard of it).",
"It's much, much, much more likely that there is a problem with the data f... | [
"Why would it be shocking if the solar system really ",
" aligned with these background patterns? It has a 1% chance of being within 0.9 degrees of these features. Not cosmically small by any means."
] | [
"I assumed he was talking about the way inflation makes everything look like its moving away from us.",
"Again, I'm going to assume that by \"cosmic inflation\" you mean expansion, which not only \"makes everything look like it's moving away from us\", it does in fact "
] |
[
"Why is the graph of Water Density vs. Temperature in Celsius a parabola?"
] | [
false
] | In my physics class our teacher was talking about finding the equation for water density in relation to degrees Celsius. I looked it up and found the graph, but contrary to what he initially thought, the graph was exponential rather than linear. Why is it that the relationship between the two isn't a linear function? | [
"So generally speaking, the graph is parabolic with a local maxima at ~4 C. This is because there are two opposing mechanisms changing the density as we increase temperature.",
"The first is fairly intuitive, the thermal expansion of water with increasing temperature. As we add greater thermal energy to the syste... | [
"The reason why the density of water decreases below 4°C (even if not frozen yet) is that the H2O molecules are asymmetric polar molecules, meaning that the oxygen atom is dragging the electrons of the two hydrogen atoms slightly closer to the oxygen atom. This leaves a \"side\" of the individual molecules slightly... | [
"What are the other substances with same behaviour?"
] |
[
"Could you make a star go supernova by throwing planets at it?"
] | [
false
] | null | [
"The impact causes the star to go supernova, destroying the entire solar system. Ignoring how you would actually accelerate planets to that speed, is the outcome realistic? would it actually send a star into supernova? ",
"No.",
"If anything, what you're describing would produce two high energy jets of particle... | [
"You shouldn't think of any of this like conventional collisions. You should think of it like particle accelerator collisions. There is so much energy and momentum that they're not just going to hit each other and stop, they're going to produce cascades of particles which are also traveling at a significant fractio... | [
"There should be sufficient momentum for much of this matter to plow right through the star and burst out the other side, like a bullet through a watermelon. ",
"I think the idea is that since these two \"planet-bullets\" are hitting polar opposite ends of the star at the exact same time, they will collide in the... |
[
"Why do you hear identical notes differently when they are played on different instruments?"
] | [
false
] | What accounts for the fact that a flute sounds different than a piano, which sounds different than a guitar (even if they all play the same note)? | [
"The note is based on the \"fundamental frequency\" of the sound, which is lowest frequency of the note. From there, you have higher frequency components (often multiples of the fundamental frequency). These higher frequencies are called \"overtones,\" and the relative levels of them determines the timbre, and is l... | [
"A simple example of this: vocal formants, the different sounds you can create while singing the same note are dependent upon the resonances of the vocal tract. \"Ah\" \"Eh\" \"EE\" \"Oh\" \"OO\" are all the same pitch but with different peaks in the spectra. Those overtones matter A LOT. "
] | [
"http://en.wikipedia.org/wiki/Timbre",
"It has to do with the relative ratio of frequencies that are produced when the instrument resonates. For every fundamental frequency that an instrument produces, standing waves are also produced that give the instrument its distinct tone. ",
"Additional info:\n",
"http:... |
[
"Do all brain-owning animals descend from a common evolutionary ancestor? Or are there animals that developed brains \"independently\" of other species?"
] | [
false
] | Forewarning: My science-fu isn't fantastic, so excuse the somewhat informal, "dude, science is awesome" language. Brains are amazing things. It blows my mind (heh) to even think about animals that don't possess them (like jellyfish). Recently, I got to wondering ... do all animals that have brains have them because we ... | [
"Nearly all metazoans (animals) have nerves (that is, cells with a synaptic junction that can transmit signals from cell to cell via an action potential), with the exception of sponges, an early outgroup on the metazoan tree. So, yes, all extant animals, including all bilaterians (animals with bilateral symmetry, l... | [
"The answer is that it's sort of complicated. Brains are made of neurons, and basically everything with neurons shared a common ancestor far enough back that had neurons. Many things that don't have brains, like nematode worms with less than 20 neurons, are included in that list, though. As you go up the tree of... | [
"My Marine Biology is weak - can you elaborate or link on how Cephalopod brain architecture is different?"
] |
[
"Do crystal deodorants work?"
] | [
false
] | [deleted] | [
"I don't know why you'd be surprised that people who insist on using a straight-razor in this day and age might eschew other convenient advances..."
] | [
"I did some home comparison testing with the crystal deodorant a while back. Crystal on one armpit and conventional on the other. Then crystal vs no deodorant. Repeated for several days with each comparison. \nI found it did provide some protection, but not nearly as good as conventional deodorant. The effect also ... | [
"You can bring an aerosol deodorant in your checked baggage. I do it all the time.",
"What is a \"crystal deoderant\"? A chunk of alum? That'd work, but it's not the best kind of deodorant."
] |
[
"Does Bell's inequality rely on photon polarisation being undefined before measurement rather than simply unknown?"
] | [
false
] | My reading of EPR is that simple values such as momentum must have a value even when not measured, which flies against the uncertainty principle and wavelike nature of particles. I've tried reading Bell's papers and subsequent ones and I can't tell whether they rely on the photon having an uncertain polarisation before... | [
"When you measure polarisation, the answer is either + or -. If you measure two entangled particles along the same axis, you always get opposite (correlated) answers. If you measure along orthogonal axes (90° apart) you get results that are uncorrelated with each other. Measure with 180° separation and you always g... | [
"I was thinking about photon's though, which are used in most of the tests. The probability of passing a polariser is cos",
" (\\theta), where theta is the angle that light is polarised in.",
"No matter what happens to the other photon, the probability of it passing a polariser is always going to be this cos",
... | [
"So, to confirm how I understand it, the Bell's test photon synchronicity experiments do not rule out that the pair of photons both have a definite but unknown polarisation before they are detected?",
"Are they simply ruling out a hidden variable that would take away randomness from the measurement?",
"It rules... |
[
"How does mirror matter behave?"
] | [
false
] | The standard model is invariant under P-symmetry (reflexion in a mirror). What happens to things like magnetic fields or cross product which have an orientation? How does mirror matter interact with regular matter? I made a much more verbose post basically asking the same question but apparently that's not the appropri... | [
"The standard model is invariant under P-symmetry",
"Actually, the weak interaction violates P symmetry maximally. As far as we know so far, all neutrinos, for example, are left-handed. That is, their spin and momentum vectors point in opposite directions. Or, even less jargony, all neutrinos have an intrinsic an... | [
"No, sorry, that's not what I'm saying. I was saying that the universe almost has P symmetry, but not quite. If you were somehow able to flip the parity of every particle at once, most phenomena would be the same.",
"If there is mirror matter, it interacts through it's own set of mirror bosons. Bosons are the par... | [
"Thanks for your answer, it made things clearer. So if I understand, the magnetic field and the cross product orientations are conventions, and if we change both the changes cancel each other in the formulas.",
"I read that the weak interaction is only used in beta decay and in the formation of deuterium. So mirr... |
[
"Can bacteria survive low temperatures like when frozen into ice-cubes?"
] | [
false
] | I have a question about water borne diseases. I am a undergrad student living in New Delhi, India. I don't have much money or a place for a refrigerator so to quench the need of cold drinking water, I buy ice cubes from the market and mix it with the 20-liter mineral water kegs. The purity of the mineral water kegs ca... | [
"Bacteria can survive freezing. We routinely do so in the lab to preserve them over the long term. In those cases, we add some cryo-protectant substances like glycerol, because ice crystals will damage many bacteria, but freezing and thawing is not a reliable way to kill bacterial cells. "
] | [
"Bacteria can survive, however, you should be fine drinking it unless there is a cholera or some such outbreak. Your immune system is already primed for most bacteria found in the water just due to living there so if you feel sick or there is an outbreak as I said above then stop using the ice but otherwise should ... | [
"Like superhelical said, microbes can survive freezing. While it is possible that since when water freezes it expands that when the water inside the cell freezes it could lyce the cell, it is not a good way to kill bacteria or other microbes"
] |
[
"I once heard that if you wore glasses that turned your vision upside down for about 3 days and you took it off, you would see the world upside down. Is this even possible?"
] | [
false
] | null | [
"Yes. Early psychologist George Stratton wore glasses that turned his vision upside down for 8 days straight. By the third day, he was seeing the world completely as normal -- as if he wasn't wearing the glasses. He could tell things were wrong if he concentrated, but normally scenes appeared completely normal. Aft... | [
"What's the difference?"
] | [
"Light enters our eyes and should make the world appear upside down",
"You're thinking of the eye as if it were a camera that takes a picture, physically places it somewhere in your head, and then your \"mind's eye\" looks at that. ",
"What's actually happening is that a bunch of cells in your eye are sending ... |
[
"A lot of nutritional supplements for someone with a reasonable diet have questionable health benefits. Are there any that have rock solid evidence of benefits?t"
] | [
false
] | null | [
"Examine.com has a really extensive list of supplements and their supposed benefits with links to studies. It seems the most proven are creatine, vitamin d, fish oil, and magnesium if there's a deficiency. "
] | [
"link for the lazy: ",
"Examine.com"
] | [
"Data is Beautiful",
" has an (in my opinion very neat) interactive data visualization that ranks various supplements by their evidence quality (sources listed and solid) and claimed benefits. \nIt was last updated in 2011 though, I'd also like to hear something else and more recent."
] |
[
"Is it fair to state that the vomeronasal organ is actually an auxiliary olfactory sense organ?"
] | [
false
] | I am not a scientist by any means, and am really looking for helpful information on this subject. I am curious as to why Jacobson's organ is specified as an auxiliary olfactory sense organ and am worried that it may be an anthropomorphic statement. I do know that it uses similar (maybe the same) portions of the brain t... | [
"Since no one else has answered yet, I give this a shot.",
"There are three reasons supporting the idea that Jacobson's organ is an auxiliary organ that provides stimuli comparable to smell/olfaction. 1. Jacobson's organ develops from the olfactory placode during embryonic development, so evolutionarily speaking ... | [
"Honestly, it's not my area of expertise, so I don't know what the criteria for an auxiliary sense organ are. I was responding to this statement ",
"the phenomenology of one sense is so drastic from that of another that they cannot be compared from a linguistic perspective",
"Based on the physiology of Jacobson... | [
"I appreciate the answer. So if I am understanding this correctly we (by we I mean you and the scientific community) don't have a strict list of characteristics for what would constitute an auxiliary sense organ, but rather use what appears to be a property cluster of sorts to verify whether there is novelty in the... |
[
"Bullet gives opposite reaction on the gun when comes out. Does torch light give opposite reaction when switch on?"
] | [
false
] | When the torchlight switches on, the light comes out of it light-speed. So does it give any opposite reaction on the torchlight, like a bullet and gun? | [
"Yes, but the effect is vanishingly small. Ultimately, this comes about because light is a carrier of energy and momentum and this holds true whether you're considering the classical or quantum picture. ",
"There's even situations where this is pretty important:",
"\n",
"https://en.wikipedia.org/wiki/Radiati... | [
"Yes, light has momentum p=E/c, E energy, c speed of light. My torch lamp has voltage U=4.5V, mass m=0.4kg, battery capacity at most Q=30Ah. So in space I can accelerate my lamp to about v=p/m=E/(mc)=QU/(mc)=4mm/s, which is more than I expected (in case my calculation is correct)."
] | [
"To follow up on that, assuming this is a typical flashlight with a battery that can power the lightbulb for several hours (let's say 4 hours), that means the actual acceleration felt by the flashlight is approximately 280 nm/s",
" or about 2.8 x 10",
" g's. ",
"Additionally, this is all assuming the flashli... |
[
"What exactly causes the \"seeing stars\" phosphenes?"
] | [
false
] | By this, I mean phosphenes that result from standing too quickly, sneezes, low blood pressure and so forth. What's the basic route from one of these events to stimulation of the retinal cells, if that's in fact what's happening? | [
"I am not a biologist but from my understanding, it stems from a mixture of 1. a temporary lowering of blood pressure which drains blood from the upper body quickly and 2. the resultant excess of carbon dioxide in the blood stream which impairs the eyeball's oxygen/Co2 pump and so in a sense robs certain rod/cones ... | [
"AndrewKemendo is indeed correct. Standing up too quickly can cause a drop in blood pressure which can stimulate the retinal ganglion cells. There's also a number of other ways this can happen, like rubbing your eyes, and retinal detachment. ",
"However the root cause of all these are essentially identical. The r... | [
"That does help, thank you!"
] |
[
"Do all planets in our solar system revolve on the same plane?"
] | [
false
] | Are there any accurate diagrams of the planes that all the planets orbit on? If Earth suddenly changed to let's say to a plane 90° off of its current plane would there be any noticeable differences? | [
"Not exactly the same plane, but close to one another. There \"average\" plane of the planets' orbits is pretty close to the orbital plane of Jupiter, usually within a few degrees except for Mercury which is six degrees inclined. This is called the ",
"invariable plane",
"."
] | [
"A few years ago I programmed a representation of the Solar System in Javascript, you can open it in a webgl-enabled browser (Chrome for example) and is visible here: ",
"http://mgvez.github.io/jsorrery/",
"All the planet's positions and orbits are calculated using data from Nasa JPL, so are accurate, as are th... | [
"That's tricky to verify, because we are much better at detecting solar systems where that is the case (e.g. all the planets pass between us and their star). So it appears that other systems orbit in a common plane, but we might not be able to detect it if they didn't.",
"The reason planets tend to orbit in a com... |
[
"What's keeping us where we are in the solar system? I mean, I know the gravitational pull of the sun keeps us in orbit, but what keeps us at this distance instead of closer or further away?"
] | [
false
] | I mean, the earth has a gravitational pull, and it's keeping us more or less glued to it unless we make a strong enough effort to break free. So why doesn't the sun's pull glue us to it? Why does it pull us close to it but no closer? Why are the really big planets so far back? Wouldn't the mutual pull of larger bod... | [
"Drop a ping-pong ball into a martini glass. What keeps it at the bottom?",
"One of the great lessons of science is that every system tends toward its lowest energy state. A ping-pong ball in a martini glass stays where it is because that's its lowest energy state. In order to make the ping-pong ball climb out of... | [
"Why is the earth traveling at this speed?",
"Because it has no way of getting rid of its momentum. First law of motion, and all that: An object in motion will continue moving at a constant speed and in a straight line unless acted upon by an outside force. No (significant) force opposed the Earth's orbital veloc... | [
"This awesome little thing here",
" is a good way to get a \"feel\" of what you're asking. ",
"You can adjust their masses and velocities and play around to see what can make a successful orbit! I also shows what happens if you are too slow/small/close and the planet smashes into the star and if you're too fas... |
[
"Can someone please explain brain freezes? (Causes, what going on when you are having one, ect.)"
] | [
false
] | All I really know is I get one whenever I eat ice cream or a smoothy or something cold. I also know that it can be stopped by putting your tongue to the roof of your mouth. Why does this stop it? | [
"It's caused by redditors who don't use the ",
"search function",
". ;) "
] | [
"For those too lazy to click: ",
"It's referred pain from your palate via the trigeminal nerve. This nerve serves your head, but it passes by the palate. When it senses the constriction of local capillaries caused by the cold, voila, ice cream headache. The brain interprets it as pain from the head due to the fun... | [
"http://en.wikipedia.org/wiki/Ice-cream_headache#Cause_and_frequency"
] |
[
"Why do streams of ejected liquids break continuous form and lump together into separate projectiles?"
] | [
false
] | To elaborate, I mean why does the water from a hose break into pieces as they fall. Or like | [
"But this phenomenon is observed in sand which, for all intense and purposes, has no intergranular adhesion ( ",
"source",
" ). Additionally, laminar flow is seen in liquids where no break up of the stream is observed. Whilst surface tensions/ energy will have an effect I think this question fundamentally needs... | [
"To my knowledge, droplet formation is spontaneous even in laminar liquid threads. (That is, if you're not seeing it, look farther along the thread, because it's kinetically limited.) See ",
"here",
", for example."
] | [
"I believe its due to the cohesive properties of water molecules. Due to the negative (H) and positive (O) charges of the individual elements that make up water, water is very much attracted to other molecules of water. When water forms a droplet, it is in the lowest energy state. By this, I mean that water molecul... |
[
"Does the efficiency of a nuclear power plant depend on the level of uranium enrichment? And if so, where is the “sweet spot” of enrichment?"
] | [
false
] | Context: I was reading a little on the Iran nuclear deal in the news and they mentioned that the deal limited them to a pretty low percentage, but the Iranians had considered making a plant that could produce up to 20% enrichment. A quick google search suggested 80-90% enrichment is needed for weapons.... so what would... | [
"The term \"efficiency\" is a loaded word when it comes to engineering, so you'll need to be more specific if this isn't what you're looking for.",
"Typically, when we talk about the efficiency of a power plant we're either talking about (1) the theoretical thermal efficiency expressed as the ",
"Carnot efficie... | [
"At higher levels you need to refuel the reactor less often. For example US nuclear submarines use highly enriched uranium so they only need to be refueled one every 30 years or so. A civilian reactor on the other hand needs refueling about once a year."
] | [
"You can engineer nuclear reactors to serve many different kinds of ends. You can make a reactor that uses natural uranium (.7% U-235) fuel, but you require specialized moderators (heavy water or very pure graphite) for that. If you enrich it to 2-5% (\"low enriched uranium,\" or LEU), you can do it with natural wa... |
[
"When we see the dark part of the moon when it's not a full moon is it reflecting mostly starlight or earthlight?"
] | [
false
] | null | [
"Mostly Earthlight. Starlight is negligible compared to the brightness of the Earth."
] | [
"The reason that you can see the dark parts of the moon is that they're lit by the reflected sunlight from the daytime side of the Earth. The city lights are totally negligible.",
"The bright side of the moon is lit by sunlight."
] | [
"It's called Earthshine.",
"http://en.m.wikipedia.org/wiki/Planet",
"\" Earthshine is reflected earthlight visible on Moon's night side. It is also known as the Moon's ashen glow or as the old Moon in the new Moon's arms.\""
] |
[
"How is an apple a 'false fruit', strawberry a fruit while its seeds are nuts and a cucumber a fruit?"
] | [
false
] | We looked into a handbook for biological technical terms and got more questions than answers when we tried looking up 'stawberrry'. Apparently the apple is a false fruit and a cucumber a fruit. Hence the question - why is the categorization so confusing? | [
"\"false fruit\" is an old term not really used any more. The term accessory fruit is used instead.",
"These terms are used to outline how the fruit is formed. A cucumber is a true fruit as it is formed from the swelling of the ovary. Strawberries and apples are accessory fruits, which means they are formed from ... | [
"Wikipedia -- Accessory Fruit",
"A cucumber is a fruit because it is a product of a flower and contains seeds, as are tomatoes, peppers, squash, peas, etc.",
"Intelligence is knowing a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad."
] | [
"why is the categorization so confusing?",
"Because:",
"A. Scientists are not perfect so while they generally strive to explain their ideas as clearly and simply as they can, they can sometimes fail at that.",
"B. Not all scientists agree on all subjects so some can use a different terminology to others.",
... |
[
"Are there any meta studies that demonstrate a strong relationship between twice yearly dental cleanings and a decreased risk of cavities?"
] | [
false
] | I am on the prowl for some evidence based dentistry. Does anyone have a link to any good research, preferably randomized, controlled trials, that strongly link twice yearly professional cleanings with a decreased risk of cavities or periodontal disease? | [
"It could be true as long as you brush & floss your teeth at home, too. I mean, sure, you can go in for a professional cleaning, get the tartar build-up removed, get an air-flow polish etc but it only takes 12-20 days for the dental plaque to mineralize and cause tartar build-up (if you don't brush well) which lead... | [
"I wasn't hoping to eliminate all dental care save for biannual, professional cleanings. Rather, I was wondering if the professional cleanings themselves have been shown to have any influence on the likelihood of having a healthy mouth years down the road. "
] | [
"Oh, of course, I know that's not what you meant, but in my experience I have seen people who came in to get professional cleanings because they thought it was enough for them to have a healthy mouth but did not brush nor floss efficiently at home. \nBut getting your teeth scaled and air polished not only removes s... |
[
"Can anyone elaborate on the Iron-Sulfur World Theory?"
] | [
false
] | I am a curriculum writer currently revising a lesson on biomolecules for high school biology. Part of this lesson requires students to analyze and evaluate various theories of how complex biomolecules could have formed on our planet. Students are to examine 3 theories: the Oparin-Haldane hypothesis, the RNA world theo... | [
"After a brief overview of the theory I have a little insight for #3. The most important aspect (to me) is that it gives a method of concentrating and organizing the cellular machinery. That solves the biggest issue that I've seen with abiogenesis, the argument that it would take billions to trillions of years form... | [
"This is a great question and it truly blows my mind that you're teaching this to high school kids, because I just heard about it my 2nd year into PhD study.",
"Essentially, you won't find a biologist who will say that iron-sulfur chemistry doesn't partially define life on this world. It's an awesome study becau... | [
"Well to be fair, I'm not actually the one teaching it. I was a HS Biology teacher for a time, and now I work for a non-profit group that is creating a comprehensive, online STEM curriculum for classrooms across the state of Texas.",
"The particular lesson-component I'm currently developing involves students res... |
[
"Biologists: Why does lack of oxygen cause necrosis so quickly in brain tissue."
] | [
false
] | As title, I looked at the wiki pages on brain death and cell necrosis, but I didn't find an explanation of why lack of oxygen causes cell necrosis as opposed to just temporary lack of functioning until oxygen is returned. I assume it's some kind of damaging by-product of the neurons function, but I'm just guessing here... | [
"Your brain cells are some of the most energetically demanding cells in your body, and your brain as a whole accounts for about a quarter of all sugar and oxygen demands throughout your entire body.",
"One reason is the synapse itself, an incredibly complex piece of molecular machinery that is continuously remode... | [
"Without oxygen, the cell cannot create enough ATP to function. There is an anaerobic pathway for making ATP, but neural tissue is too energetically demanding for so little ATP. It has to maintain numerous ion pumps to maintain cell membrane voltage and ion gradients. It has to synthesize a lot of protein and a lot... | [
"Thanks for the reply, That helps me narrow down my question. But I still don't understand what happens when there is no oxygen that causes necrosis. I'm trying to understand what actually causes the cell to self destruct rather than wait dormant for more oxygen to arrive. Is it some biological pathway that end up ... |
[
"If someone were sitting in a bathtub full of water, but didn't drink any of the water, would they still become dehydrated?"
] | [
false
] | null | [
"Yes. You need to ingest water."
] | [
"He's 100% right."
] | [
"Yes. Your skin is not optimized for absorbing water and couldn't possibly keep up with your body's demands. Your kidneys would give out because there wouldn't be enough water to filter with which would cause imbalances in a whole host of things like sodium, potassium, etc."
] |
[
"I have a science degree but I'm not yet prepared to study some areas of physics. What math should I review, and what math should I study to understand the meaning behind quantum equations?"
] | [
false
] | [deleted] | [
"What areas of physics are you interested in?",
"For undergrad physics (until special relativity and quantum mechanics), linear algebra and differential equations are everywhere. You should also know at least the cool results from multivariable analysis (gauss, stokes, etc), and the theory to solve laplace's and ... | [
"the topics that will be particularly necessary are matrices (linear algebra) and gradient/curl vector calculus. "
] | [
"Yes, quantum mechanics at the level of computation is almost completely linear algebra. If you want some more deeper insights, functional analysis will also be required.",
"For magnetism and superconductivity, eventually you'll have to learn some field theory. But once you have the maths for QM/Electrodynamics, ... |
[
"Why can I smell static electricity?"
] | [
false
] | Maybe I cant smell static itself, but there is a particular odor I always attribute to static. Am I smelling something else or does the static have an affect on the air creating a unique scent? | [
"The most likely source of the smell is from the ozone created by the electrostatic discharge - that is, static shock. When a spark is created between your body and, say, the doorknob, the air molecules along the spark path are ionized. If the spark is strong enough, it can also break some of the molecules apart.... | [
"Yes, nitrogen will also break and form nitrogen oxides. Sorry, I don't have information about the relative rates available. Ozone has a much more pungent smell than nitrous oxide, however."
] | [
"What about the nitrogen? Does nitrogen react with oxygen to form nitrogen oxides to an extent comparable to ozone formation, or is the N2 molecule too stable for that?"
] |
[
"Do plants die of old age?"
] | [
false
] | can plants die of old age? if so how old do they get? Edit: Thanks for the great answers everybody | [
"The process you are talking about is ",
"senescence",
", specifically organismal senescence. The whole process of senescence in and of itself is not entirely figured out and there are competing theories for what is actually happening, but we do understand that there are fundamental differences between the proc... | [
"Yes. ",
"Here is an excellent review article",
" on the basics of plant telomeres and telomerase function in higher plants (using ",
" as the model system.)",
"I don't really feel qualified to explain much past that. I don't work with ",
" or really dicots at all (I'm a grass person), and as such most of... | [
"You are amazing. This is an incredibly specific topic, and in the grand scheme of knowledgeableness, you're probably one of the most informed people in this thread on this topic, and yet, you still have the humbleness to say \"I have a limited understanding\".",
"It is true - \"Education is a progressive discove... |
[
"Why does hearing your voice played back with a delay essentially nullify your ability to talk?"
] | [
false
] | So I came across an app that, when activated, plays back your own voice with a configurable delay. When it's activated your ability to talk is vastly reduced. There was a group of us playing around with the app the other day and while we were all effected to varying degrees one of my friends was the most susceptible. V... | [
"I experienced this effect some years ago when playing with some audio software, it's most odd!",
"The best explanation I've sourced is from this patent, ",
"Voice delay feedback apparatus",
".",
"... in order to speak properly humans typically require audio feedback between what they say and how they hear ... | [
"This is exactly it. If you pay close attention to what happens under these conditions, you will notice yourself slowing down your speech to \"wait\" for the echo to catch up. In essence, speech isn't just a matter of sending signals from your brain to your mouth and vocal cords - the feedback you get from your a... | [
"The feedback is not about the skill itself, but about the environment. You have to adjust the way you speak based on the local acoustic environment. If there's a lot of noise, you have to speak louder. If there's a lot of reverberation, you have to speak more slowly. The experiment we're discussing isn't pertu... |
[
"When they repave a road, where do they send the old asphalt and what is its environmental fate?"
] | [
false
] | null | [
"Usually, the asphalt is immediately recycled into the new road surface through the process of ",
"pavement milling",
". If the pavement isn't immediately recycled into the new road surface, it is trucked somewhere and then re-sold as aggregate or as an input to \"new\" pavement.",
"Asphalt is one of the mos... | [
"Yep! Asphalt is basically just rocks and glue. With old asphalt, the glue is all dried out, but the rocks are just fine. Crush it up, add glue, asphalt. "
] | [
"So it just gets broken up and remelted on the spot? That's really cool."
] |
[
"How does hyperparathyroidism and hypercalcemia cause hypomagnesemia?"
] | [
false
] | How does hyperparathyroidism and hypercalcemia cause hypomagnesemia? I know it's pretty far-fetched, but I've tried google but to no avail. Yes, I've read my books, but I couldn't wrap my head around the concept. Answers are really appreciated. Thank you! | [
"Magnesium is primarily reabsorbed by the thick ascending loop of Henle along with Calcium that occurs along the paracellular route.",
"It is known that hypercalcemia or hypermagnesiemia alone inhibit further reuptake in the kidney. Also, there is some calcium inhibition of magnesium transport as well.",
"Does ... | [
"Hyperparathyroism usually causes increase in activity of osteoclast which causes increase breakdown of calcium from bone and lead to increased calcium in plasma resulting in hypercalcemia.",
"The hypercalcemia calcium comperitively inhibits tubular reabsorption of Mg2+, which causes hypomagnesemia."
] | [
"so calcium and magnesium have competing pathways? or is it a limit with the transporter? "
] |
[
"Is there a fundamental evolutionary explanation for why almost every tract in the CNS crosses to the opposite side?"
] | [
false
] | [deleted] | [
"One hypothesis looks to the ancestors that first had this feature, the worms.",
"The usefulness of crossing nerves is that an impulse on the left side causes the right to contract, which pulls away from the thing that touched it.",
"Since switching back would be improbable, we appear to be stuck with it."
] | [
"This is not definitive - but it is suggested it is related to the optic chiasm.",
"Eyesight is the primary tool by which we determine how to interact with the world. We see in stereo, hence nerves from the eyes cross to both sides of the brain. This is the optic chiasm. The information from the eyes is split, an... | [
"I've heard that if you get attacked from one side, and get injured on the right side of your head for example, the left brain can still control your right arm to fend off the attack."
] |
[
"Why do blue flames not give off more light than orange flames?"
] | [
false
] | I noticed this when was in a mostly pitch black room. My butane torch produces a blue flame that illuminates very little of a reasonably sized room, however if I widen the flow and allow the flame to turn orange the whole room is lit up. From what I've learned blue flame is the hotter of the two. Shouldn't more heat... | [
"There are a couple of things going on here (such as the \"surface area\" of the flame), but the main thing is how we see light. If we extrapolate your example to even hotter flames that are mostly ultraviolet, the room would go back to appearing dark. Our eyes are evolved to see light based on the Sun's spectrum, ... | [
"Hotter flames produce more light at all wavelengths as black body emitters, so there are no dark flames."
] | [
"Yes, thank you for the correction. I was thinking just of peak wavelength and not ",
"intensity",
". The laser argument is invalid then, since the flame is at varying intensities. However, the UV flame produced ",
"would not be visible",
", especially if a flame emits mostly in IR and UV like hydrogen, so ... |
[
"After an amputation, whether it be a finger or an arm, how does the body reroute blood flow?"
] | [
false
] | Quickly checked wiki for an answer, didn't find much about it. Thanks for your time! | [
"Not sure what you mean. When the part is amputated, the surgeon will ligate the arteries going to it and the veins coming out of it. Everything proximal to the amputated part will still have arteries and veins going to it. The heart pumps as it usually does; the baroreceptors will continue to monitor pressure; and... | [
"For me I was taught that the circulatory system is similar to an electrical circuit. So in an electrical circuit if you cut off half of it, the circuit would stop working because it would no longer be closed. Why is it not like that?"
] | [
"Because it's not just one loop out to the limb and back. Along the way to the end of, say the arm, the brachial artery gives off branches that serve all the structures along the way. Branches for the upper arm muscles, bones, nerves, and skin, then the forearm muscles, bones, nerves, and skin, and so on. And each ... |
[
"Why are ethanol bottles in the chemistry lab labelled 'staining reagent' ?"
] | [
false
] | null | [
"I think perhaps your lab in question are using the receptacles of what used to be a staining reagent - which is s chemical used to dye or “stain” microscopic specimens - such as when you will be using an electron microscope and you want to distinguish between two differing tissues, however ethanol is not a stainin... | [
"For gram staining one of the steps is to rinse away excess of the colored staining chemical with ethanol or an ethanol/acetone mixture. This step is usually called decolorizing, and takes only a few drops of the solvent at a time. Are they irrigator bottles or something similar?"
] | [
"If it's also used as a microbio lab, probably because it's used as a decolorizer for various staining techniques (not limited to gram stain - there's quite a few differential stains that use ethanol to decolorize)"
] |
[
"Why aren't tape worms digested if they live in the digestive track?"
] | [
false
] | Meant to say tract instead of track as has been noted in the comments | [
"Tapeworms attach themselves to the wall of the small intestine so they can obtain nourishment. The scolex, (the head of the tapeworm) has hooks and suckers which helps the tapeworm to stay attached to the wall lining and to resist the peristalsis action of the intestine (peristalsis is the contractions of the musc... | [
"Most part ot the deconstructive part of the digestion happens in the mouth and stomach, cists traverse this areas protected, then colonized the intestine walls. Intestine walls main function is absortion of lipids and proteins and water from the biological matter that has already passed the stomach, is not a harsh... | [
"That's where the force comes from right?"
] |
[
"Let's just say there is zero friction in our world. Is it possible to pierce with a sharp object? How faster and far would a person slide?"
] | [
false
] | null | [
"Thank you for your submission! Unfortunately, your submission has been removed for the following reason(s):",
"guidelines.",
"If you disagree with this decision, please send a ",
"message to the moderators."
] | [
"wow they weren't kidding when they said about this subreddit's horrible guidelines"
] | [
"You are basically asking what would happen if a fundamental law of physics was broken. It is impossible to have a scientifically accurate answer for that."
] |
[
"Toilet Flush -- Is the idea that urine and fecal matter are \"aerosolized\" and spread around the room true?"
] | [
false
] | Basically, i've heard it said by many people my entire life that when you flush the toilet whatever is in there ends up turning into vapor and is spread around the room. (Not of it.) Is this true? A moreover, does closing the lid--which has nothing even resembling an airtight seal--alleviate this problem with any sig... | [
"the hazards of urine and fecal matter are greatly over estimated by most people. These things are better thought of as fertilizers than as toxic waste."
] | [
"A pity, I cannot read ",
"this article",
". Here is quote from the abstract:",
"The studies demonstrate that potentially infectious aerosols may be produced in substantial quantities during flushing. Aerosolization can continue through multiple flushes to expose subsequent toilet users. Some of the aerosols ... | [
"Fecal-oral transmission is a fact of life. Some poopy bacteria are going to end up on the kitchen counter, on your toothbrush, in your nose, and so forth, probably no matter what you do.",
"I'm not suggesting that you stop washing your hands. It's worth fighting the good fight. I'm sure there are a host of paper... |
[
"How, exactly, do we fall asleep?"
] | [
false
] | What is the process going on in our brain? How do we get to that "off" switch? | [
"Is NREM 2 the stage where you're paralyzed? I wake up with sleep paralysis quite often. "
] | [
"Is NREM 2 the stage where you're paralyzed? I wake up with sleep paralysis quite often. "
] | [
"You're paralyzed during REM to prevent your body from acting out the dreams you have during those stages "
] |
[
"Do space stations lose air from using air locks?"
] | [
false
] | null | [
"https://en.wikipedia.org/wiki/Quest_Joint_Airlock",
"https://spaceflight.nasa.gov/shuttle/reference/shutref/structure/airlock.html",
"https://www.nasa.gov/centers/johnson/pdf/123834main_iss_eva_sys_checklist.pdf",
"As part of the depressurisation cycle the ISS quest airlocks use pumps to pump air from the ai... | [
"It would cost more to orient the station in such a way to make use of the minuscule thrust than it does to periodically correct orbital degradation/wandering due to airlock decompression. The station is low enough that they have to make fairly frequent corrections anyways."
] | [
"\"It is possible to calculate the station's drag force from the information in this graph. This is left as an exercise for the reader.\""
] |
[
"How do phased array antennas receive signals?"
] | [
false
] | I can understand how a phased array helps direct outgoing radio waves by pointing the major lobe of the transmission towards the "receiver", but how does any sort of flat plate collect incoming radio waves as well as or better than a semi-spherical (?) dish? | [
"The simple answer is that a suitably-designed phased array of the same size (same cross-sectional area) as an equivalent dish would be expected to perform approximately ",
" (in terms of directivity and signal-strength). On those basic measures, it can't really perform ",
" than a dish.",
"In a receiver, the... | [
"u/noshowtho",
" If you understand how a phased array can steer its output, then you are well on your way.",
"With a dish setup, all the energy for \"pings\" originates from a relatively concentrated point (which sometimes IS a small phased array) sitting at the focal point of the dish. You probably know that t... | [
"(Digital) Signal-processing is a very broad field, but very powerful and important in modern communications systems.",
"As examples, you get audio signal-processing for lossy compression (bit-rate-reduction) and echo-cancellation and speech-recognition, and signal processing of radiofrequency signals in any \"di... |
[
"What would happen if you were underwater as a tsunami went over you?"
] | [
false
] | null | [
"http://www.youtube.com/watch?v=L5IbDi09Yb4"
] | [
"That was amazing, thank you."
] | [
"I was wondering about that...But as a surfer, I've dove under 25 foot waves, and it didn't feel like suddenly being 25 feet under.",
"Anybody want to explain the physics of water pressure under a wave?"
] |
[
"If all viruses were effectively eradicated, how would that affect humans, ecosystems and other organisms?"
] | [
false
] | I've seen an increasing amount of articles about this miracle cure that could kill any and all viruses. Although I am still very skeptical of the drug's capabilities, what would happen to earth's ecosystems if any and all viruses were removed from the face of our planet? Are there organisms on earth that are mutually d... | [
"The most abundant form of viruses actually infects bacteria, not humans. Bacterial populations affect every living ecosystem on earth and are a very abundant part of the microenvironments within the soil and within higher order organisms. The impacts of this hypothetical scenario would be large, but it's difficult... | [
"Yeah even the drugs he's talking about (DRACOS) only target specific dual strand rna replicating viruses, not \"all\" in any sense."
] | [
"Bacteria use viruses as one way to exchange genetic material amongst themselves.",
"I asked this exact same question to a viral expert and they couldn't name any other good examples of any sort of beneficial relationship with viruses, but it may be just because people haven't looked."
] |
[
"When physicists say that the fabric of spacetime will be torn apart if the Big Rip model is true, what does that mean?"
] | [
false
] | Could someone elucidate the idea of spacetime getting ripped apart by accelerating expansion? What would be the physical description of this scenario? Does this mean that time itself would cease to exist? I know that there are certain fields inherent to space, such as quantum and Higgs. What would cause these fields to... | [
"Technically, it means that the scale factor becomes infinite in finite time. The scale factor describes the expansion of the universe. Right now, the scale factor is 1 by definition. There was a time where it was 0.5. Pick two arbitrary distant galaxies. Their distance was only half of what it is now at that time.... | [
"An exponential function doesn't blow up in finite time, but another type of function might. The typical accelerated expansion (dark energy dominated era of the universe with an exponential scale factor) isn't a big rip.",
"https://en.wikipedia.org/wiki/Scale_factor_(cosmology)"
] | [
"You're simply confusing expansion happening forever and the acceleration of that expansion increasing exponentially. Let's say I have a magic balloon that is capable of being blown up at a steady rate forever without popping, that's expansion. Yet if I blow it up faster and faster then at some future point it won'... |
[
"Why do most humans have negative associations with harmless spiders and bugs, while very neutral or even positive associations with deadly mammalian predators (bears, lions, wolves)?"
] | [
false
] | null | [
"Bears and wolves actually leave humans alone for the most part. They won't come into our camps and attack our tribes. And the fear of insects is largely cultural rather than an evolved trait. Many cultures do not think about insects as we do. Many places simply see them as a food source, as you or I might see a sh... | [
"It might be a form of xenophobia. "
] | [
"I think it's a cultural thing. A lot of cultures aren't creeped out by spiders. Instead, THEY EATUM UP. Also, there is a stronger relation between bears/pups with humans than there is between a wasp and a human. More relatable I guess. "
] |
[
"Do black holes preserve the appearance of their supernovae?"
] | [
false
] | I saw a documentary and it began explaining that black holes would essentially suck in the supernova at the point of collapse but to the outside universe all we would see is the supernova before it actually collapsed since we cannot see beyond the event horizon. My question is, would all the black holes in the universe... | [
"From the perspective of an external observer things that approach the event horizon never reach it. That is true. However the light emitted is redshifted (to that same observer) more and more as the object approaches the event horizon. This means you can't \"see\" it as it won't be in the visible spectrum. Also ev... | [
"Thank you for your response!"
] | [
"So if you were to watch someone fly a space ship into a black hole, they would sort of fade out reddish until you couldn't see them anymore, but never look like they reach the black hole?"
] |
[
"How strong are the magnetic fields around power lines?"
] | [
false
] | Curious for above ground, underground, and long transmission lines. Also if its possible to provide a comparison of power to something else, I'd be much appreciated. | [
"The formula for the strength of the magnetic field is proportional to the current and inversely proportional to the distance.",
"The maximum power generation capacity of, for instance, Big Bend Power station near Tampa is 1.73GW. Big Bend is a large coal-fired plant. Assuming a 110kV transmission line, the cu... | [
"110KV line-to-line 3 phase would only be 9080 Amps."
] | [
"At the power plant I used to work at, it was pretty intense. The 345,000 volt lines that were 30 foot above ground would induce a voltage in the ground. At about a two foot distance you could pick up a one thousand volt potential differance."
] |
[
"Can everyone in the world share in the modern standard of living?"
] | [
false
] | [deleted] | [
"According to a mathematical model by Hulett in 1970 if everyone in the world had the same standard of living as people in the US the resources of Earth could support about 1 billion global population.",
"So it depends on what you mean by standard of living. (As Cam-ille said)"
] | [
"Economics graduate here. Actually, a fair wage is a very controversial concept. What in the United States is considered a fair wage, may considerably exceed a fair wage in India, for instance.",
"Taking that into account, there is a common misconception that the wealth of some can only be sustained if some other... | [
"they don't have the opportunity to produce valuable goods or service...",
"hold on a sec - everything we have pretty much comes from these 1$/day countries. Even our apple iphones - those are pretty valued in our economy, yet I am sure the people who make them are not paid \"fair wage\". So I disagree, they are ... |
[
"Was potassium-40 always present on the surface of the earth? Would it have been a part of the human diet before mined fertilizers/nutrients were used in agriculture?"
] | [
false
] | [deleted] | [
"Yes and yes.",
"It's got a billion year half-life. Suffice to say it's had time to get distributed around.",
"Edit: Also, why do you ask? Because that sounds like a bogus argument invented by someone who went out looking for reasons why fertilizers are bad. With a half-life ",
" long, it's in no way a health... | [
"Yes, on both counts. Potassium-40 is naturally occurring, therefore it's always been there. Your body needs certain amount of potassium to live, and potassium-40 is a portion (albeit small) of all the potassium available. You will likely have potassium-40 in your body regardless of what you eat, or where that ... | [
"Potassium-40 is an extremely long-lived isotope (with a half-life of over a billion years). It was likely produced in the supernova that seeded and helped trigger the formation of our solar system about 5 billion years ago and has decayed to a slightly lower level since. Similarly, U-235 was produced by the same s... |
[
"Could a torpedo break the speed of sound of water, while travelling through it? What would happen?"
] | [
false
] | [deleted] | [
"This is mildly wrong in several places.",
"First and foremost: it would not be the same. ",
"You are correct that the speed of sound is infinite in an incompressible material. There is, in fact, no such thing as an incompressible material. It is a rather useful idealization engineers can use for certain sit... | [
"It would be the same. Shockwaves et al. The speed of sound is in fact a measure (well sort of) of the compressibility of a medium. In a truly incompressible medium, speed of sound is infinity.",
"So a torpedo breaking the speed of sound would cause a very similar reaction as in air. The answer is similar for you... | [
"Oh nice :) I actually researched cavitation for quite a bit when I was getting my MS, but it completely slipped my mind when replying to this question!",
"So cavitation would prevent the onset of supersonic flow itself?",
"EDIT: Some googling reveals that shock waves in water are indeed, different from shock w... |
[
"What would it feel like to be in a motionless spacecraft hovering above the earth (not orbiting)?"
] | [
false
] | If weightlessness is a product of freefalling to earth like the astronauts and cosmonauts on the International Space Station experience as they orbit the earth, then what would it feel like to if the ISS was not in an orbit but able to stay at a fixed altitude above earth? Would you be able to stand? How much gravity w... | [
"It would be the same as what you already feel. You're rotating with the Earth because the Earth is spinning, but this is way slower than orbital speed, and only makes a small difference. There's no big difference between standing in a building that's stationary on the surface, and standing on a floating rocket pla... | [
"Imagine getting on a hot air balloon that is sitting on the ground. Would you still fill gravity when you are standing in the basket? Now imagine it takes off, and it hovers a few feet off the ground, would you feel gravity then? Then it slowly gains altitude, and lets say there is no wind, so it \"hovers\" above ... | [
"It's from the center of mass (of the Earth). That means if you go to an altitude equal to the radius of the Earth (6300 km), you'd feel 1/4 the normal gravity. By my quick calculations, if you go up about 1000 km, you'd feel around 75% normal gravity."
] |
[
"Cells -->Tissue...When?"
] | [
false
] | How many cells congregated together does it take before we say they have created "tissue". How many are needed / at what point do they start to actually function as muscle, bone, an organ, brain structures/spinal cord, etc., rather than just existing as a collection of cells. What causes them to take on and start per... | [
"Tissue is not simply defined as a certain number of cells. Rather, it is cells that have adopted a certain organized architecture; the cells take on a structure consistent with their function. Cells have ",
"polarity",
" and specialized roles depending on their position -- ",
"check out how detailed* structu... | [
"Answers so far have been great, thanks very much, everyone. ",
"I think what I'm wondering is, at what point / why would you look at a collection of like cells and no longer say \"There is a bunch/group/formation of [HUVEC / breast / kidney] cells starting to gather and organize.\", but instead say \"There is [... | [
"Cells in a culture dish are not usually identified as tissue. In fact, we would normally discuss tissue in the context of living systems. There are perhaps some exceptions, as always. For example, scientists are now growing muscle in culture -- so called synthetic ",
" meat",
" -- which might be described as m... |
[
"How deep could humans make it into the Earth's crust?"
] | [
false
] | How deep could we possibly make it into the earth before pressure or heat destroys the materials we used to get there and us with it? Edit: follow up question, what technology could we develop in the next 50 years to see us be able to go farther into the earth. | [
"Most geologists will tell you that the ",
"Kola Superdeep Borehole",
" is the deepest in the world though technically there are a couple oil wells that have gone a bit deeper. The Kola borehole seems to be about the limit with current technology. Drill bits frequently need to be replaced and once they got to... | [
"You're welcome. As for exploring deeper down, I believe there was a proposed design for a laser drill that would melt the rock around it and form a strengthened tunnel as it went. It's all pretty theoretical at this point and I don't know of plans to build one."
] | [
"This is exactly what I was looking for in an answer, thanks so much friend. I need to add a follow up question of what technology could we develop in the next 50 years to see us be able to go farther into the earth. "
] |
[
"If humans can get extra chromosomes, can other creatures get extra ones too?"
] | [
false
] | [deleted] | [
"This chimp was born with an extra chromosome",
", but he was not mentaly defective. ",
"He had some human-like characteristic, like walking upright and straight face. He also seemed more interested in mating with humans than monkeys. His is not a happy story, but at least he died in pace and quiet."
] | [
"Yes this would be absolutely possible though I'm not aware of any specific syndromes in animals. ",
"It is important to note though that the issue with Down Syndrome is not necessarily an extra chromosomes. The extra copies of the DNA, throwing off the genetic balance in the genome, is the issues. This can happe... | [
"Insects certainly can have extra chromosomes, but the effect isn't always going to be the same. In drosophila, for example, the ratio of X to autosomes (non-sex genes) determine whether the fly is male or female (though the Y gene is necessary for sperm development).",
"With normal flies it works out fine: you h... |
[
"What makes the electronic configurations of transition metals so unique?"
] | [
false
] | Current undergrad here taking a level 1000 course. (By unique I meant that I'm unable to grasp what's going on microscopically.. :( ) According to the one electron system approximation/model, the 4s atomic orbitals have a lower energy levels, translating into stability for the system and thus getting filled first. This... | [
"The problem is that the Aufbau principle is only a rule of thumb and holds mostly for neutral atoms. Even there it cannot predict the electronic configurations of all the elements correctly (e.g., Cr = [Ar] 4s1 3d5 instead of 4s2 3d4, or Cu = [Ar] 4s1 3d10 instead of 4s2 3d9).",
"This is because the Aufbau princ... | [
"Exchange energy: The exchange energy is a quantum mechanical effect between electrons with the same spin in degenerate orbitals. The exchange energy lowers the total energy of the electronic configuration and is the reason why electrons in degenerate orbitals have aligned spins.",
"I've never quite grasped this ... | [
"Spin-orbit coupling is what allows singlet to triplet and triplet to singlet transitions to occur. This type of transition is called intersystem crossing. There are other types of angular momentum coupling, but spin-orbit coupling is usually the dominant effect in molecules."
] |
[
"Why does our throat \"tighten\" when we're at the edge of tears?"
] | [
false
] | I'm sure I'm not the only one who has this, when about to cry (and I do mean sob) my throat will tighten sometimes to a painful extent. Why does that happen? Is there any use to it or is it just a thing that happens? EDIT: Didn't know if I should tag this as biology or medicine. | [
"It's called the globus sensation which has associations with hypertonicity of the UES, the upper esophageal sphincter, as well as GERD. The purpose of the UES is to keep food in and air out. Stress, can cause the UES to tighten, the exact etiology of that action isn't known, but there is an association with stress... | [
"It's not just the UES though. If it was just the UES, there would be no associated voice changes during those emotional moments. Globus sensation can occur in the absence of emotion and is just a general medical term for when patients complain of feeling a more chronic \"lump in the throat\" feeling. (I am a speec... | [
"The sources I found say that it is caused by your glottis expanding. The glottis is the opening that allows air to pass through to the lungs and the size of it is controlled by your vocal chords. The glottis also closes when we swallow. When you try to \"swallow back\" your tears, you feel a \"lump in your throat\... |
[
"How much CO^2 do volcanoes spew out when extremely active and does that have any effect on climate change?"
] | [
false
] | After reading the entries in AskScience 2012 awards I found myself wondering how much of an effect an erupting volcano would have on our climate (indirectly). I'm assuming me have mounds of data on Mt. St. Helens, if possible compare the amount of CO that the volcano spewed into the air compared to the annual amount t... | [
"There is a pretty good article by the USGS ",
"here",
".",
"In short, a volcano's effects last only few years. With a large enough eruption, the sulfur aerosols can reduce global temperatures 1-2 degrees. From the article... for CO2, Human activities are responsible for about 35 billion metric tons (gigatons... | [
"Possibly, yes. If I recall correctly there have been documented instances of limited cooling happening with exceptionally large eruptions. But again, it's temporary and would not significantly affect long term climate patterns ."
] | [
"The Siberian Traps flood basalt eruptions has been proposed as a possible factor contributing to the end Permian mass extinction. CO2 emissions from the eruption are linked to the spike in global temperature at the Permo-Triassic boundary.",
"A lot of great material ",
"here",
" from MIT. "
] |
[
"Are there strains of HIV that aren’t detectable by modern testing?"
] | [
false
] | (Edited to meet guidelines) Hello all, Are there any cases where an individual might test negative (outside of the window period) using HIV RNA PCR & antibody/antigen testing despite actually being positive? Is it possible that someone might have some weird/rare mutation that causes the HIV RNA PCR test to not detect a... | [
"The tests don’t look for single places; they check for a wide range of HIV components, and HIV effects. For a virus to avoid all the components that are tested for, it would no longer be a functional HIV."
] | [
"The term you're looking for is \"False Negative\" which is where someone is infected, but the test says no infection. ",
"This is very possible inside the window (which is why you get tested multiple times if you have a significant concern). ",
"Outside of the window, it's really unlikely. As in probability ... | [
"To build on this excellent answer, the 4th generation HIV tests have an incredibly low rate of false negative as well. Something in the range of less than 0.001% of the time. And as this poster said, if you're outside of the window period, chances are astronomically small of having a false negative, but the 4th ge... |
[
"What causes one to vomit during/after strenuous exercise?"
] | [
false
] | null | [
"While this is specific to one case, they do go over some broader statistics, tragically without isolating a root cause. ",
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4027831/",
"It seems that fasting and dehydration are major factors according to a ",
" study out of Nagoya in Japan. ",
"https://www.scie... | [
"While your muscles are working harder during strenuous exercise, blood flows away from your midsection or deep organs toward superficial muscles/skin (O2/temperature). Just like in flight/fight stress response, digestion comes to a halt. If your stomach is very full, but not digesting it can feel uncomfortable or ... | [
"I have always wondered if it has something to do with the body “shutting down” digestion processes to divert all energy to the exercise."
] |
[
"Why does fruit get sweeter (or more flavorful) as it ripens?"
] | [
false
] | I can't explain why I want to know the answer to this but... I want to know the answer to this. Reddit? I'm sure there's something you know here. I'm counting all fruits here, even the perennial last kids chosen for te team, avocados and tomatoes. | [
"tldr: starch (unripe storage form of sugar) is broken down to it's basic units, which are typically things that taste good to us.",
"slightly longer version:\n",
"http://www.ccmr.cornell.edu/education/ask/index.html?quid=1174"
] | [
"If you're asking \"why\", it is because fruit seeds are better spread by getting eaten, so making them taste better is a good way of encouraging that. If the seeds weren't transported by the process of digestion, the trees would spread slower and compete with themselves, as the seeds would end up near the origina... | [
"Thanks!"
] |
[
"Burning Methane question (about the arctic methane)"
] | [
false
] | Hello all i know next to nothing about chemistry just read this article about a huge Methane deposit that is going to release sometime in the future and its impact Question is why can't they just burn it? i think it creates co2 / h2o when burned, but wouldn't the released co2 be less damaging? (probably wrong i know no... | [
"The nature article is ",
"here",
" for anybody who is interested.",
"It's likely to be hard to just burn the methane because the release won't happen in one place. It will be spread out in the form of plumes of bubbles scattered over thousands of square miles. And that's an area that gets seasonal sea ice ... | [
"Did you even read the article? Using the numbers you provided that would be a 5 times increase in the amount of methane in the atmosphere. That seems like a huge deal. ",
"According to the EPA: ",
"Pound for pound, the comparative impact of CH4 on climate change is over 20 times greater than CO2 over a 100-yea... | [
"I'm not here to argue the merits of anthropogenic global warming. No matter where you stand it could still increase atmospheric methane by 5 times and according to your number it would release 1.25 times the total yearly CO2 output. If you believe in global warming this will have a huge impact (equivalent of 30 ye... |
[
"Dry Shampoo: How does it work?"
] | [
false
] | So short answer is that my roommate is pretty much telling us that dry shampoo doesn't actually clean the cat. He says the dirt molecules that were there before are still there. All the dry shampoo is doing is sanitizing the cat and making it smell delightful. So my question; is he right, and is the dry Shampoo just... | [
"Dry shampoo is baby powder/corn starch mixed with some fragrance. It just soaks up the oil in your hair. "
] | [
"Ok, so it pretty much doesn't actually get rid of the stuff, right? So if you use it, you would still have to scrub pretty decently to get rid of the filth right?"
] | [
"It soaks up the oil and makes your hair less shiny... But you also now have hair with an extra thing (dry shampoo) in it. It's exactly like putting face powder on oily skin. Not quite the same as washing."
] |
[
"Why does a near-light-speed astronaut age slower than the earth, and not vice-versa?"
] | [
false
] | According to the theory of relativity, the faster something travels, the slower time moves for it. So, if an astronaut leaves earth and travels close to the speed of light, he will feel like 2 years have passed on his journey, but when he returns to earth, 40 years will have passed (or whatever). However, from the astr... | [
"When the astronaut turns and returns to Earth, his reference frame changes. This isn't relative. Both observers will agree that the astronaut is the one who changed reference frames. "
] | [
"No. All velocities are relative. That postulate - that the laws of physics are the same for all inertial reference frames - is really the basis upon which special relativity is built.",
"Honestly, I wouldn't take what ",
"/u/NilacTheGrim",
" is saying too literally. I've never seen that explanation before, a... | [
"Both observers travel through spacetime. You can trace out the \"length\" of their path through spacetime. When the astronaut is leaving earth, you're right. Both observers can be viewed to be stationary and everything is nice and relative. ",
"To each observer, his own path in spacetime during this scenario is ... |
[
"Why does herpes only appear in the mouth region and the genital region?"
] | [
false
] | [deleted] | [
"You're asking specifically about \"herpes simplex I\" and \"herpes simplex II\"; as other answers point out there are several other herpes viruses (a total of 8 known for humans alone) that specialize in different regions of the body/different tissues.",
"As part of HSV I and II's lifestyle, they set up latent i... | [
"Herpes viruses",
" can express anywhere on the body. For example, varicella (chickenpox) is a herpes virus. ",
"Herpes Simplex",
" (STD herpes) generally are present in mucous epithelium, which is most commonly found around the mouth and genitals. However, it can also effect the eye. Other herpes viruses ca... | [
"This extends to Herpes relatives like chicken pox. When the virus reactivates as Shingles, any involvement with the eyes is considered very serious. Vision can be affected, sometimes permanently. Antivirals are usually prescribed to limit the damage."
] |
[
"Does 0.9c appear the same to all observers?"
] | [
false
] | We all know that the speed of light appears the same to all observers, regardless of reference frame. However, if you were to say an object is traveling at 0.9c (or any other fraction of c for that matter), would it appear the same to all observers? Or is what appears to be 0.9c to one observer 0.5c to another? | [
"No. In the object's rest frame is appears at rest. In any other reference frame it can be at any speed. Only in one specific frame will it appear that speed.",
"You are currently going at 90% the speed of light in some reference frame, does it feel special?"
] | [
"that may not be that impressive",
"Well, it's still impressive in ",
" reference frame where such speed requires a great amount of energy to accomplish. The matter is slightly complicated also because those protons are experiencing centripetal acceleration as well, keeping them on the track--acceleration is ",... | [
"I think you're missing the point, which is that all inertial rest frames are equally valid."
] |
[
"How does a food processor keep bacteria out of packaged goods?"
] | [
false
] | I understand that "cold pasteurization" is used at packaging plants. The website indicates it is used for fruit, poultry and seasonings. What about diary products like packaged sliced cheese? Those packages will keep for a long time if they are not opened. And it seems that if any bacteria were present in a sealed cont... | [
"For Dairy, it depends on the product. In the US just about all dairy products are pasteurized which is rapidly heating the milk before processing to kill bacteria while minimally affecting flavor. Also preservatives are often used. Note that one of the most common preservatives is salt. Food processors also us... | [
"re: vacuum sealing. thanks, does that include anaerobic bacteria in sealed plastic packages?"
] | [
"If anaerobic bacteria were on the surface or inside the object being vacuum sealed (which is unlikely). Also many bacteria need specific environments to grow. "
] |
[
"Tired of glasses - really. How safe would Lasik be considered, in general?"
] | [
false
] | null | [
"someone please answer this. i could also benefit"
] | [
"Lasik is as safe as the person operating the machine. I had a long talk with my optometrist about it and essentially, there are people who are valid candidates for Lasik and people who aren't. You need to find a doctor who isn't just trying to get as many people through as possible. Someone who knows the machine ... | [
"ok, full disclosure. ",
"i work in neurology/neurophysiology field.",
"people who own the EMG/NCV machines seem to do many many more studies than the guys who don't. the guys who \"rent out\" time from the hospital or the neurodiagnostic lab.",
"the reason being that the guys who own the machine get money e... |
[
"What effect does the moon's gravitational pull have on dry land (as compared to the tide for water)?"
] | [
false
] | Is there any measurable or significant effect on dry land like the rides? I read an article about that moon of Jupiter that is stretched and compressed so intensely that its surface pops like a zit I was just wondering what it would be like for there to be a moon but no oceans, what effect would there be if any at all... | [
"Yes, there is a similar tide for the solid Earth, usually called the ",
"Earth tide",
", though the ",
"magnitudes are small, amounting to a few to 10s of cm of vertical change",
" compared to the tides in the ocean. The magnitudes are such that it's not something you're going to notice without instrumenta... | [
"Thank you! Lots of neat stuff to dive into"
] | [
"I'm not sure, maybe I'm telling you something you already know -- and if so, I apologize.",
"But to me your question implies a common misconception about why the rather small tidal forces (in regards to earth) of the moon/sun create such noticeably big bulges of water on earth. The reason is not because the moon... |
[
"Have we observed any effects on the Earth related to our position in our galactic orbit?"
] | [
false
] | null | [
"So 240 million years = 1 Galactic year.",
"The earth is only about 8 Galactic years old.",
"Man is only a Galactic day or so old."
] | [
"The earth takes about 240 million years to orbit the galaxy so nothing has been directly observed over the span of civilization. Ice ages however are thought to be influenced by our position in the galaxy and the resultant changes in cosmic ray flux."
] | [
"More like 13.5 Galactic years.",
"If we divide 240 million years by 365, a Galactic \"day\" would be 650,000 years. IIRC our species is around 200,000 years old, so not even a day old in Galactic term."
] |
[
"Is it impossible to gain weight without consuming carbohydrates (without your body producing insulin)?"
] | [
false
] | I recently finished an interesting book, "Good Calories, Bad Calories" by Gary Taubes. While the book has several big flaws, overall it is very valuable as it shows how many current nutritional/medical "facts" are not based on good science. In the book one of Taubes's main assertions is that it's impossible to gain wei... | [
"Insulin secretion is not only carbohydrate dependent. Fat in the intestinal lumen induces secretion of hormones (GLP1, GLP2, GIP, Neurotensin, PYY), and at least some of these stimulate insuline secretion. ",
"If you block all insulin secretion, it is true that you would lose weight (like type 1 diabetics). If y... | [
"I don't think you will get a definitive answer here.",
"However, there are a few things to consider.",
"First, it's not just glucose that stimulates insulin secretion. It's also stimulated (to a lesser degree) by fats, and probably proteins.",
"Second, insulin isn't the only thing that promotes fat storage i... | [
"People say that because his views are contrary to mainstream opinions. However, his books are well-written, and more importantly, he cites peer-reviewed literature extensively throughout them.",
"Unfortunately in science there can be bias against new information that conflicts with previously-held longstanding ... |
[
"For someone who needs to consume more calories than average, like an olympic swimmer, do they still need to stay within the daily recommended saturated fat, fat, cholesterol, etc limits? Or does the ratio increase based on overall caloric consumption."
] | [
false
] | Title basically says it all. For example, does a weight lifter need to get the extra calories from protein or could he also increase fat/ cholesterol intake without getting fatter or raising his bad cholesterol and/or lowering good. | [
"Consuming fat does NOT make you fat. Consumption of excess calories causes the body to store them long term as fat via lipogenesis. ",
"That said, breaking down fats for energy is a more difficult process for the body than dealing with carbohydrates. A person engaged in strenuous exercise could certainly increas... | [
"Normally diets are broken down into macro nutrient ratios. Macro nutrients (fat, protein, and carbohydrates) are all parts of a healthy diet and take up a certain amount of your diet (like 40% protein, 40% carbs, 20% fat). If your calorie consumption has to increase to match physical activity, then so do your over... | [
"I've heard that one in that case would not ",
" to stay within the recommended amount, but it is prefared to do so (and instead increase protein and carb intake). Further on the person continued and claimed that the percentage system (f.ex. 40-40-20% named earlier) was outdated. Can't find the source though."
] |
[
"Genesis of elements in a nuclear explosion"
] | [
false
] | I know that essentially all elements in the universe heavier than hydrogen are the product of runaway fusion in supernovae. I also know that a nuclear explosion produces radioisotopes from neutron absorption, but are there measurable amounts of elements heavier than lithium created when a hydrogen fusion bomb explodes,... | [
"I know that essentially all elements in the universe heavier than hydrogen are the product of runaway fusion in supernovae",
"This isn't quite correct. In the first few minutes after the Big Bang, hydrogen and helium form in copious quantities (about 3/4 hydrogen, 1/4 helium), along with tiny amounts of lithium ... | [
"Stellar nucleosynthesis is only the majority up to sodium. Past that, the majority of the atoms in the universe are from supernovae nucleosynthesis.",
"As far as fission products, the fissile chain is fairly easy to follow. Pu-239 -> U-235 + He-4 -> Th-231 + He-4 -> Pa-231 -> 227 Ac (+ He-4) ... -> Pb-207. It's ... | [
"Past that, the majority of the atoms in the universe are from supernovae nucleosynthesis.",
"Not quite correct. About half is created in the ",
"s-process",
" in giant stars. Some is created in the ",
"rp-process",
" in thermonuclear flashes on neutron stars. The other half is made in the ",
"r-proc... |
[
"Why do clothes feel crunchy when you air dry them, but soft out of the dryer?"
] | [
false
] | null | [
"Tap water has minerals dispersed in it in solution. When it dries on a line the fibers/threads stiffen because the clothing is not moving much, and the threads retain their shape as the water evaporates and leaves the minerals behind, while in a tumbling dryer the threads are constantly crunched and tugged and squ... | [
"i'd say even then tumble drying will be softer as the fabric fibres are massaged while drying, and won't stick together.. kinda like how wet pieces of paper stick together if they dry while touching.. water allows the little hairs on the fibres to tangle and hold like velcro, whereas agitation while drying breaks ... | [
"So if you were to use distilled water for washing your clothing, air dried clothing would come out the same as dryer-ed clothing?"
] |
[
"If an electron is knocked out from the L shell of an iron atom, leaving behind a vacancy, or hole, from what energy shells can an electron make a transition to fill the hole and emit an L X ray?"
] | [
false
] | null | [
"An electron from any orbital which can make the transition without violating conservation laws. Using the electric dipole approximation, it would have to come from another orbital with opposite parity, and the angular momenta of the initial and final states should differ by 0 or 1."
] | [
"What"
] | [
"What is the context for the question?"
] |
[
"Proof the moon affects the tides?"
] | [
false
] | My brother and I were having a few drinks and chatting, when he started talking about gravity. Mind you neither of us are very scientifically literate but I'm smart enough to know not to talk out of my ass when I don't know something. He went on to try and tell me that there's no way the tides are caused by the moon ... | [
"The mass of all the world's oceans is less than ",
"2%",
" of the mass of the moon. The moon is not a lightweight and has a significant gravitational effect on the Earth.",
"Now in a simple water-world model, the tides would look like ",
"this.",
" However, the Earth has continents which get in the way a... | [
"The bulge on the far side is ",
" caused by inertia. It is caused by the gravitational gradient. This is a common misconception that makes it into elementary textbooks and popular science descriptions.",
"The textbook \"Planetary Sciences\" by de Pater and Lissauer devotes Chapter 2.6.1 to a mathematical deriv... | [
"Why is there a bulge on the other side of the Earth?",
"I've read ",
"http://en.wikipedia.org/wiki/Tide#Forces",
", but still not sure about how the Moon is supposed to weaken local gravity on the other side?"
] |
[
"Why do we, in the United States, use the metric system with respect to energy consumption?"
] | [
false
] | null | [
"The reason for this is that there are no U.S. customary units for \nElectric current, Resistance, Potential Difference, or charge, simply because the ability to measure these has only really been around since the world switched over to metric. (The metric system was put into use in most european nations around the... | [
"The real question is why don't you use the metric system for everything else? "
] | [
"1 watt = volt * amp = ohms * amps",
" = volts",
" / ohms",
"it all ties together!"
] |
[
"How big could insects and arachnids get?"
] | [
false
] | [deleted] | [
"Within the fossil record there's evidence for dragonflies with up to 70cm wingspans in the carboniferous (",
"http://deepblue.lib.umich.edu/bitstream/2027.42/62968/1/375117a0.pdf",
"). This is inferred to be related to an uptick in oxygen concentrations, as one of the limits for invertebrates is their respira... | [
"It depends on oxygen concentrations in the atmosphere. The higher the concentration the bigger they can get, hence having larger insects back in times when it's generally thought these concentrations were higher.",
"As to a theoretical maximum I'm unsure, and at higher levels of oxygen concentration you would pr... | [
"Higher concentration of oxygen in the past lead to bigger insects; many insects grew larger due to diffusive oxygen intake. This means oxygen was easily supplied to tissue even though their surface area was greater. However, the growth of insects can not carry on ",
". Take spiders for example; the design of th... |
[
"Why are some cancers incurable?"
] | [
false
] | Chemotherapy of course has its own drawbacks, but I can't understand how some types of cancers aren't completely eliminated by aggressive chemotherapy. I'm not talking about returning cancer but rather about cancers that can't "go away" in the first place. | [
"Immunotherapy for renal cancer was only developed 20 years ago. without that I would be dead now.",
"Chemotherapy is not universal. It only works on some cancers. Cancer is not one disease. It is hundreds of diseases.",
"Radiation treatment is fairly universal but it has dangerous side effects when used on som... | [
"Because some cancers don’t respond to chemotherapy drugs, each of which target different proteins mostly in fast-dividing cells. If a particular cancer (or group of cancers) doesn’t have those proteins, then it won’t respond to chemotherapy."
] | [
"Because hitting every cell of a specific type is hard with how our bodies process things. Chemo is just poison that you try to outlast compared to every cell of cancer. Sometimes one survives or resists and comes back.",
"To really cure cancer, we need to develop cancer specific killing or removal methods, curre... |
[
"According to Maxwell's theory of Electromagnetism, visible light is a combination of fluctuating Electric and Magnetic fields. So why don't we see a compass needle being deflected in the presence of, say, a light bulb?"
] | [
false
] | null | [
"The fluctuating magnetic field associated with visible light is fluctuating very very quickly. It's reversing directions 100's of trillions of times per second. The needle of a compass simply has too much mass to respond quickly enough to such a fast variation in magnetic field. And if it did, it would be changing... | [
"Besides the speed and low intensity of the perturbations, light from normal light bulbs is not polarised, so the orientation of the magnetic field in each wave is random and tends to cancel out with another wave."
] | [
"The oscillation might be only billions (or 100's of millions) of times faster than a high speed camera can see, rather than trillions. It's still absurdly faster than any available technology can respond to."
] |
[
"If quantum effects reign supreme in the microscopic world and relativistic effects dominate the macroscopic world, at what level of scale do the two compete with one another for dominance?"
] | [
false
] | Why is it that I am a collection of atoms where each follow quantum rules, yet the me as a whole does not suffer quantum effects (being at two places at the same time, entangled with some other macroscopic object, etc.) | [
"Quantum physics is intrinsically probabilistic. That means, the outcome of quantum mechanical experiments can only be predicted using probabilities. ",
"Due to this inherently probabilistic character, quantum mechanical effects get \"averaged\" away in macroscopic ensembles. ",
"The ",
"Ehrenfest Theorem ",
... | [
"Well, not ",
" quantum mechanical effects.",
"Superconductivity and topological insulators are both intrinsically quantum effects which nevertheless manifest on the macroscale. Quantum mechanics isn't just about the probabilities; sometimes the form of the wavefunction, and they symmetries of the system, are r... | [
"Why is it that I am a collection of atoms where each follow quantum rules, yet the me as a whole does not suffer quantum effects (being at two places at the same time, entangled with some other macroscopic object, etc.) ",
"A tossed coin has a 50% chance to land on tails and 50% chance to land on heads. The mor... |
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