title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"What is the smallest weight difference perceivable by the human hand?"
] | [
false
] | What is the smallest weight difference between two objects that I would be able to notice just by picking the objects up? | [
"Its called Differential threshold or 'Just Noticeable Difference' and theres too many factors to give it a value"
] | [
"There's a law in my medical physiology textbook (which I can't recall currently but will update when I find, but it might be \"Differential Threshold\" mentioned before) that stated humans can detect about 10% change in sensory stimulus.\nFor example, if you are holding 10g, you can detect a 1g increase. However i... | [
"Exactly, There might be an average out there, but there are varying levels of sensitivity involved. "
] |
[
"What is the significance of the c^2 term in Einstein's famous equation (E=mc^2)? Does it reflect some sort of radial symmetry?"
] | [
false
] | null | [
"If you take the length of something and square it, you get an area, not another length. If you take a speed and square it, you get distance",
"/time",
", not another speed.",
"Saying c",
" is faster than the speed of light doesn't make any more sense than saying an acre is longer than a mile."
] | [
"The best way to think of it is as a conversion factor. When we look at the mathematics of relativity, it's all much simpler and much more symmetric if we choose units such that c=1, a unitless value. These units are therefore called natural units, and in using these units, we find that for an object at rest E=m. O... | [
"A co-worker of mine ridiculously claims that since nothing moves faster than then the speed of light, the speed of light squared doesn't mean anything",
"Did you point out that c+1 = c+1 just means c = c but represented differently, and nothing breaks the speed of light there?",
"e = m * c",
"is also",
"m... |
[
"Is there a more technical name for when something 'settles'?"
] | [
false
] | The only two things I can think of is nail polish and mustard. If you leave them for a long time the water/liquid moves to the top. Shaking/stirring it up put it back to rights. | [
"An emulsion is a type of colloid in which one liquid is dispersed through another (immiscible) liquid. Colloids are basically mixtures of materials where one is dispersed through another. ",
"http://en.wikipedia.org/wiki/Colloid",
"In actual fact I think both nail varnish and mustard are probably sols - a type... | [
"I believe the term is ",
"Emulsion",
". Segregation is when it seperates out."
] | [
"There's also sedimentation."
] |
[
"How does total pressure (as supposed to partial pressure) affect the diffusion of components in a mixture?"
] | [
false
] | Scenario A: You have a tube with a permeable membrane in the center. On one side 50/50 water and alcohol on the other pure water. Pressure between the sides are equal. Scenario B: it's exactly the same as scenario A except that at time 0 you inject an amount of water into the 50/50 side (making it no longer 50/50). So Volume, molarity of alcohol, and temperature haven't changed but pressure has. How does the diffusion of alcohol compare between the two scenarios? | [
"I'm having some trouble parsing this. If you add water into one side then volume and molarity of alcohol both change. Volume changes because liquids aren't compressible. By \"molarity\" do you mean the amount of alcohol? Because molarity means molar concentration."
] | [
"A simpler version of this would just be \"pressure is applied to the 50/50 solution side of the membrane\". Like ",
"u/Twink_Ass_Bitch",
" said, what happens depends on how permeable the membrane is. If it's permeable to both, the solution from ethanol side will move to the water side until pressures are equal... | [
"Tell me if I'm off base here but it was my understanding that liquids are only mostly non compressible. That liquids being non compressible was a rule of thumb because for most things they are. But in reality they simply have very large changes in pressure for small changes in volume.\nMolarity is moles/Liter. And... |
[
"As humans what fears are we born with and which do we learn?"
] | [
false
] | I always presumed we were born with the fears of falling and loud noises. The rest to me was picked up from our adult peers. Is this assumption correct or are new borns hardwired with other survival instincts? | [
"According to psychologists James Kalat and Michelle Shiota in their book ",
", \"Sudden, loud noises frighten virtually everyone, from birth through old age. That fear is also present in virtually all other animal species, except those without hearing.\" They next suggest that separation from loved ones may be a... | [
"Falling, loud noises, and any experience that causes pain are the only natural fears."
] | [
"Interesting stuff.... thanks for the responses:)"
] |
[
"How realistic is the cancer \"vaccine\" talked about recently?"
] | [
false
] | A recent post to is talking about a cancer "vaccine" talked about in this . All sorts of claims have been made about cancer in the post. So, how realistic is this? | [
"So, immunotherapy has long been seen as a holy grail for cancer treatment. The immune system is naturally programmed to attack cells that have gone a bit weird (to use the scientific term). The problem tends to be that the cancer cells can also alter themselves so that they are disguised from the immune system, or... | [
"Frankly, in a field where even the possibility of inching forward is worth celebrating, it's very nice to think we may be able to take a full stride."
] | [
"Ah, I see. Thanks for the information.",
"So, in summary it is very promising, however there are still some concerns that need to be further looked at."
] |
[
"I've always wondered: What is the evolutionary advantage of acne?"
] | [
false
] | Well, there probably isn't any, but what's the advantage of the increase in oil production that causes it? Before you hit puberty, your skin is clear and seems perfectly healthy. During and after puberty, your pores go haywire for no apparent reason, the only noticeable effect of which is a proclivity for infection and swelling. Why on earth do they do this? | [
"For a trait to be retained, it doesn't necessarily have to be evolutionarily advantageous - just not disadvantageous.",
": Please see ",
"this comment below",
" for a more complete answer to OP's question."
] | [
"Subem is that oil, from the sebaceous gland, that P. acnes, the anaerobic bacteria that causes acne, likes to live in. Subem would normally waterproof hair or fur in other animals, but humans don't have enough for this to be effective. ",
"The trait is probably neutral, but since it does cause acne it may even b... | [
"This means that people with acne have, at least in the past, been able to procreate at some time. Fear not!"
] |
[
"Somebody please explain how sidewalks and roads crack?"
] | [
false
] | null | [
"Most often from the material expanding (heat from sun) and contracting (cooling at night). The never ending cycle cracks the material. Once cracked, water can get into the structure and freeze. This accelerates the deterioration.",
"Secondarily, the sub-base can settle if not properly compacted. It can also ... | [
"Metals rust and therefore become weaker and unattractive. It would be costly to change or take care of them. Also, the fact that metals are typically good conductors and therefore not so safe. However, rust is an insulator so that problem is solved when metal rusts(I'm not sure how good of an insulator it is thoug... | [
"Would a metal road peform better with respect to these issues? What are the disadvantages of a road made of metal?"
] |
[
"Should I throw a apple core when in the outdoors or just keep it and throw it to the garbage later?"
] | [
false
] | So I was eating an apple at the beach the other day and it got me thinking. Is it less harmful for the environment if I just throw the core or any organic waste right in the outdoors or keep it and throw to the rubbish instead, where it will be together with a ton of non organic materials that will not decompose? And what do YOU do? | [
"In the Environmental Science class I TA'd for in grad school, each semester we had a guest lecturer from the local landfill come to talk about what a landfill is, how it is constructed, how it works, etc. etc. etc.\nShe actually made a point of saying that due to conditions in the landfill (compression and anoxia ... | [
"As a back packer, I can say that you should be careful what you do with organic waste that may contain seeds. There's almost zero chance that your apple core will result in an apple tree that disrupts the ecosystem of your suburb. However, if you are in a national park or some other delicate ecosystem, just pack... | [
"I don't meed in the streets. I mean when you are in the mountain/beach/forest."
] |
[
"How does the electromagnetic theory of light explain intensity?"
] | [
false
] | Before Einstein introduced the quantum theory of light, what was the explanation given for different intensities of light of the same frequency? Because intensity is amount of photons per area per second but that means you had to consider light as quanta which the em theory didn't do. Is there any fault in my thought process? Thank you! | [
"Photons are not necessary to understand the intensity of a classical light wave. The explanation you mention is just how the quantum description of light is reconciled with the classical theory.",
"The classical case of electric dipole radiation is worked out ",
"here",
". You can see that the field strength... | [
"Electric and magnetic fields can have about any strength you want. If you set up a giant capacitor, you can crank it up to generate an electric field inside as strong as your equipment can handle.",
"In an electromagnetic wave, you have an oscillating electric field that generates an oscillating magnetic field t... | [
"Thanks! I found a similar explanation on stack exchange some time after making this post, thanks for confirming!"
] |
[
"As the Sun loses it's mass does this mean that it is also losing it's gravitational pull on the Earth causing the Earth to move further away from the Sun?"
] | [
false
] | [deleted] | [
"Yes.",
"The sun is slowly losing mass, which implies that the orbital radii of the planets is gradually increasing (though this is very insignificant). Also, when the sun begins to transition to a red giant, it will shed about 1/3 of it's mass, causing a significant change in orbits."
] | [
"So we're doublefucked. Sun is dying and we're getting farther away. And the sun gets to swell up until it nearly engulfs earth, before it dies. The future feels depressing. We run out of resources, our Sun dies, and the entire universe expands until rips itself apart. Does it have to be that sad? "
] | [
"It's so far away we will likely have moved to another planet/solar system/galaxy or exterminated ourselves by then. Also consider that homo sapiens as we know them have only been around for about 200,000 years, so it's also likely that we won't be the same species. A lot can and will happen in the next 5 billion y... |
[
"What are our realistic alternatives for a smooth transition from fossil fuels?"
] | [
false
] | With world oil production being at a plateau since 2005 with an expected terminal decline within 1-4 years, it's past time we found a way to retrofit our current infrastructure. Are there any viable sustainable alternatives? | [
"I'd be interested to see where you got those numbers. The oil companies have found significant new reserves in the last few years, and the increasing oil price is making formerly uneconomic reserves economic again.",
"Either way, to be frank the only other power source we have which can produce anything like the... | [
"Only nuclear, by at least an order of magnitude."
] | [
"It would almost certainly be through biofuels. There's been quite a lot of work in developing 'drop-in' biofuels, that is biofuels that behave similarly enough to traditional jet fuel that the plane does not have to be modified.",
"EDIT: Oh, and for the OP, you should enjoy reading this blog. ",
"http://physic... |
[
"Is the Copenhagen interpretation still the leading interpretation of QM, or have others like the hidden variable interpretation made any ground?"
] | [
false
] | null | [
"People usually choose to drop locality because no-one has a good way to understand what dropping realism means.",
"No way, most people drops realism, this is why non-local theories with hidden variables (eg Bohmian mechanics etc.) are not that popular. Dropping locality leads to huge troubles with relativity.",
... | [
"As an Everettian, I'd like to claim that the Everett (many-worlds) interpretation has gained some ground, but I feel like I'm going to get some pushback on that.",
"In any case, I'd say regardless of whether anything else has been gaining much ground, Copenhagen has probably lost a fair amount of ground - for ex... | [
"Just for fun I will talk about Popper's interpretation (related to the ensemble formulation) since it isn't much discussed among physicists. ",
"In this interpretation we take quantum mechanics as a statistical theory from the start, after all we cannot reason from non-statistical premises to statistical conclus... |
[
"How are telescopes and space observatories arranged at the L2 Lagrangian point so they do not interfere with each other?"
] | [
false
] | null | [
"Spacecraft placed at a Lagrangian point are not literally parked at that singular point in space. In reality, they are placed in orbits with the L-point at their center. ",
"For example, the JWST will orbit L2 at a distance of about 800000 km (500000 mi). There is plenty of room. The L2 region is essentia... | [
"There's actually only one spacecraft currently located at the Sun-Earth L2 point - ",
"the ESA Gaia probe",
". Previous missions to L2 were moved to heliocentric orbits after the conclusion of the mission to avoid interference with future missions.",
"Because L2 is unstable, spacecraft located there have pro... | [
"Spacecraft there typically avoid the shadow of Earth, to do that they go in a wide (pseudo-)orbit around L2. But even if they would not: A few thousand kilometers don't matter there. For practical purposes L2 is actually a region of space orders of magnitude larger than low Earth orbit, where thousands of satellit... |
[
"It is very difficult to find unbiased information about GM crops."
] | [
false
] | I would really just like some suggestions of books or websites that offer solid, but not too technical, unbiased information about genetically modified crops/food. My goal is to come to my own conclusions about the pros and cons of GMO's and their effect on health and the environment from sources that aren't trying to persuade me one way or the other. I would prefer it to be from scientific, tested, and peer-reviewed sources that aren't written like a scientific, peer-reviewed journal articles, as I don't have a strong science background. Can anyone help? | [
"If I knew such a source and I pointed you to it, then how would you know ",
" was unbiased? Maybe I'm pointing you to a biased source which I think is unbiased because of my own biases...",
"Moreover, you're asking the wrong question. Asking whether GMO crops are bad for you is like asking whether \"plants\" a... | [
"You can't generalize risk and benefit assessments to all GM foods. You need to look at it one species and one gene at a time to really get a feel for things. For example, say you add a gene to make a tomato more frost-resistant, and you've already proven through clinical trials that the protein that gene expresses... | [
"Tell your friends that if they want to ignore science, then they can go ahead and believe in creationism too. Anyway, here's an actual ",
"scientifically peer-reviewed article about GM corn varieties.",
" This article makes a lot of the important points I made (I accidentally said that BT affects insect respir... |
[
"why are the earliest sunsets not on the same day as the winter solstice?"
] | [
false
] | The winter solstice is December 21, but the earliest sunsets are December 5th through 10th. What's up with that? | [
"It has to do with the fact that the Earth is not only just spinning on its axis, but also orbiting the Sun. The Earth takes 23 hours and 56 minutes to rotate 360 degrees, but 24 hours to rotate so the same point on the ground is facing the Sun at the same angle. The ",
"Synodic day",
" and the ",
"Sidereal d... | [
"No, this does not have to do with time zone. If you shift your time origin, you still find that earliest sunrise does not occur on the same date as solstice. It is an astronomical effect, not a horological effect. It is a real effect.",
"Both sunrise and sunset times vary periodically. Finding the minimum of sun... | [
"The solstice is the shortest day of the year, not the earliest sunrise of the year. Point of fact, it isn't even the earliest sunset of the year. The earliest sunrise may be around Dec. 5th and the earliest sunset is around the 9th-18th, but the days can still get shorter because the sunset is getting later and la... |
[
"We know that different hot temperatures kill bacteria and mold in food preparation, but can excrement from the organisms still cause health issues?"
] | [
false
] | Say for instance someone cooks ricotta cheese pie (baked for 1 hour at 350F) with moldy cheese or a potato chip manufacturer uses moldy potato in a batch. Most (if not all) bacteria and mold would die off. What about waste from the organisms (whether it be what is left after die off or excrement)? Could it cause health issues? Sensitivities? Is there a possibility of allergy? | [
"Yes, a lot of bacteria damage host tissue through toxins (called exotoxins), e.g. the bacteria that cause botulism and tetanus. A few of these toxins can be heat stable and still cause disease after the bacteria that produced them die.",
"Wiki on exotoxins"
] | [
"This is absolutely correct. Some toxins can be inactivated by heat, but toxins can persist long after the organism is dead. A common problem in medicine is treating a systemic infection with antibiotics. Something few people see or understand(and frankly we doctors don't usually take time to explain) is that in a ... | [
"Dead meat bacteria endotoxemia.",
"http://nutritionfacts.org/video/dead-meat-bacteria-endotoxemia/",
"The toxins in plant matter tend to be the kind that are intended for plants, while the ones that come from bacteria that is living in and living on flesh are understandably more virulent to your body, since th... |
[
"Can what distinguishes human beings from other beings be defined \"scientifically\"? If so, how?"
] | [
false
] | null | [
"You'd need to determine what you consider a human.",
"In other words, you're asking \"what do we define as human.\" Biologically, a human is any living organism from the genus Homo.",
"However, you could define it to be whatever you like, really. Definitions are important only in that they are what we want the... | [
"Can you refine your question, and in such a way where it doesn't involve arguments in another subreddit?"
] | [
"\"What distinguishes human beings from other beings\" is somewhat vague, but I see absolutely no reason why we wouldn't be able to make specific and falsifiable statements about particular properties that are true of human animals, yet not true of non-human animals.",
"Vague (and potentially false) examples migh... |
[
"Why do different blood types \"attack each other\"?"
] | [
false
] | Obviously they would be clumping together because it's recognized as an "intruder" but why? Why do the human body specifically invovled anti-b/a proteins just for that (well maybe there is another reason why) | [
"The body is not specifically attacking non-type matched blood, but rather the body attacks everything that is not part of \"self\". A general mechanism by which the body fights off any kind of infection is by creating a very very very diverse set of antibodies which will bind all kinds of molecules. Some portion o... | [
"Red blood cells have antigens on their surface, just like any cell in the body. Antigens can be protein, lipid, carbohydrate structures or a combination of these. Antigens are used by the body to determine self from non self. The body will make antibodies (proteins) to antigens that it determines are not \"self\".... | [
"Beautiful answer, thank you!"
] |
[
"Gravity's speed limit is also the speed of light, but is it also slowed by a medium such as air or water?"
] | [
false
] | null | [
"To be clear, it's ",
" in either that travel at light speed.",
"Light is slowed down by being absorbed and then reëmitted a short time later (or we could talk about little antennas being driven slightly out of phase, again by absorption and reëmission, but this time everything is continuous). So the question ... | [
"From the askscience guidelines: \"If you cannot clarify your answer in excruciating technical detail, don't answer at all. This is to reduce layman speculation, which is generally not helpful.\""
] | [
"Not anymore, he isn't. Hah!"
] |
[
"what is the difference between a broken neck that causes death and one that causes paralysis?"
] | [
false
] | null | [
"It depends where the injury is and how severe it is. The nerves that control your body are aligned in a specific order, basically from the legs (near the bottom of the spinal cord) up to the head (near the top). If an injury occurs in your neck that completely severs the brain from communicating to the regions t... | [
"To summarize: the higher up on your neck the break is, the more likely you are to die."
] | [
"so breaking a vertebra above approx. T2 could kill you, paralyze you in a number of different ways, or allow you to fully recover? ",
"why doesn't every vertebra above T2 have the same chance of killing me if broken?",
"*i'm using T2 b/c on the chart is looks like T2 is just above the heart and lungs."
] |
[
"What are the differences in the metabolisms of someone who can't get fat and someone who gains weight easily?"
] | [
false
] | [deleted] | [
"While this doesn't quite answer your question, perhaps it will give you some information that is part of the answer. ",
"Human microbiota (all the microbes in and on you) work has exploded in the last 10 years. One huge piece of research to come out of this is that ",
"lean people and obese",
" people harbo... | [
"People vary in their response to overfeeding: ",
"http://www.nejm.org/doi/full/10.1056/NEJM199005243222101",
"In this twin study, the subjects were overfed by 1000 calories/day, but their weight gain varied from 4.3kg to 13.3kg. The discrepancy appeared to be caused by genetic factors. A person who gained the ... | [
"Have any experiments been done with artificially influencing the microbiota population to see if weight loss results? (i.e. introducing desireable microbia, etc...)"
] |
[
"Can a polygraph distinguish between lies and normal nerves?"
] | [
false
] | First off, I apologize if this is the wrong flair, not really sure what filter it should be asked in. But I always thought if I was accused of murder and was asked to do a polygraph, just being accused and asked if I murdered someone would cause my pulse and nerves to go crazy. Can a person reading a polygraph test tell the difference between a lie and nervousness due to the pressure of the situation? | [
"Can a person reading a polygraph test tell the difference between a lie and nervousness due to the pressure of the situation?",
"Possibly. Have a quick skim of the Wikipedia article on ",
"lie detection",
". It'll be an important frame for this discussion because a big issue with all lie detection methods, p... | [
"Actually your mistaken, nervousness in not a factor since individuals are nervous when the \"test\" begins and when it ends.",
"That is what I am saying. The data is examined in an event-related manner, so any nervousness is going to be removed through baselining/normalising. At the end of the day, the poly is u... | [
"Actually your mistaken, nervousness in not a factor since individuals are nervous when the \"test\" begins and when it ends.",
"That is what I am saying. The data is examined in an event-related manner, so any nervousness is going to be removed through baselining/normalising. At the end of the day, the poly is u... |
[
"Why can't dark matter just be neutrinos?"
] | [
false
] | It seems like an obvious sort of answer, so there must be a good reason it's not right | [
"From what we know about the masses of neutrinos, they can only have been part of hot dark matter at the time of structure formation, but we know from theory and simulations that a lot of cold dark matter was needed. ",
"Hot means that they're ultrarelativistic, that is kT >> mc",
", and cold is the opposite. H... | [
"The term right-handed neutrinos is often used somewhat sloppy. It is often used for elementary neutrino-like fields that are not charged under the standard model gauge group (the \"right handed\" emphasises that they are not chagred under SU(2)_left ) . It is important to note that these particles are not to be c... | [
"So about how massive would particles of dark matter have to be?"
] |
[
"I was taught that brown eyes are dominant but my father has brown eyes and mine are green, why?"
] | [
false
] | All of my high school science classes said that brown was the dominant trait, were they misinformed or am I just different? | [
"Dominance doesn't work like that. You can have a dominant gene mixed with a recessive, so the recessive gene would be masked. In that case, your mother probably had a recessive gene as well that ended up creating the recessive green you have. ",
"I'll give you an example. Let's say E is dominant (brown), and e i... | [
"Brown is the dominant trait, but eye color isn't just coded for by one gene. It's coded for by a whole ton of different genes, just like skin color. ",
"Here's",
" a great explanation on this topic."
] | [
"Eye color depends on three genes",
". Since autosomal genes (the ones that don't determine sex characteristics) come in pairs, if one gene is brown and the other is green, you'll get brown because brown is dominant. But if you pass your green gene to your offspring, and your mate passes their green gene also, th... |
[
"Why does ice break in a hexagonal pattern?"
] | [
false
] | Does it have anything to do with the molecular structure of H20 or is it purely coincidental? | [
"Google the crystal structure of ice and you'll see that it is in fact hexagonal. Same reason why snowflakes are usually hexagons too. It's due to the bond angles of water and how water molecules interact through hydrogen bonding. I wouldn't be surprised if there were planes of weakness in the ice due to the hexag... | [
"Ice as a crystalline solid is super bizarre stuff. For example, it's one of very few substances that are less dense as a solid than a liquid, which is why ice floats. The other crazy thing is how many crystalline structures ice can form. ",
"So far, we've observed 14 unique crystalline forms of ice,",
" which ... | [
"I highly doubt that the whole ice on a lake is ",
"crystalline, so the crystalline structure of normal ice (hexagonal pattern) shouldn't affect the ice on a larger scale. If you look at the breaking pattern in the video, you can see that the angles between the different cracks are not all the same (as it would b... |
[
"What are some possible reasons that some bands aren't showing up in my gel? (PCR)"
] | [
false
] | I took a picture of my gel and some bands are showing and some aren't. I'm guessing I didn't add enough DNA or I didn't add any DNA into my PCR tubes. Could there be any other reason why they won't show? Edit: or i didn't load the samples properly into the gel edit: i'm obviously a noob at research. and brb gotta go to lab meeting Edit. Thanks for the responses. I'm guessing i didn't pipette the DNA correctly... Going to try again. I love you guys . research is the best. TIL the small amount of cardiacmyoctes that the body creates are derived from other cardiacmyocotes | [
"The first question should be do you see your ladder/ molecular marker?"
] | [
"Yeah, I just re did everything making sure that I put the DNA by staring at each tip and I got good results. ",
"Thank you sir!"
] | [
"It's hard to mess up loading the DNA...you've got blue loading dye or something in your samples? If the blue goes in the well then it's loaded, even if you miss a little it's probably fine (just be careful that some sample doesn't spill over from one well to the next though)."
] |
[
"[Physics] Suppose I had a pound or so of pure protons, about how densely could they naturally be packed?"
] | [
false
] | null | [
"Naturally, they would just blow apart due to Coulomb repulsion."
] | [
"Yes, but how far apart would they have to be such that the Coulomb repulsion is negligable?"
] | [
"Coulomb repulsion has infinite range. So if you're imagining a totally empty universe, filled with some number of protons, they will repel each other forever. If you were to smash them together into a length scale where the strong force overwhelms the electromagnetic force, you may be tempted to say that the stron... |
[
"Why can I reproduce sights and sounds in my head but not smells, tastes and \"touchs\"?"
] | [
false
] | null | [
"You might not have a very good sense of smell but really it just sounds like you don't pay as accurate attention to smell/taste/touch. Remembering/envisioning flavors is how cooks know that cacao and chilis will go together, but lamb and ice cream won't. Anyone who has ever tried to decide between perfumes has rec... | [
"I suspect that you don't actually hallucinate the sights and sounds in your head either. They are vivid but (baring psychological disorder) you can probably tell the difference between a remembered image and an perceived one."
] | [
"I suspect that you don't actually hallucinate the sights and sounds in your head either. They are vivid but (baring psychological disorder) you can probably tell the difference between a remembered image and an perceived one."
] |
[
"As an adult, is there any neurological difference between learning a new word in your first language and a new word in a second language?"
] | [
false
] | Learning a new word in your first language somehow feels different to learning a new word in your second language, even after the critical learning period. But why should it? Either way, you're learning to associate a new word with a particular meaning. | [
"Learning a language before puberty (12-13 y.o) is much easier, as the brain functions differently. Before puberty the brain could be imagined as a single unit, rather than two hemispheres that split different functions. However, after the puberty, the functions are split/ In terms of the language, the left hemisp... | [
"How are you getting your L2? Learning or acquisition? They feel different because they are different, but not because of L1 or L2 in this case. Comprehensible Input theory seems pretty applicable here.",
"FWIW, since we are discussing how new vocab feels, I completely learned my major L2 after any time that coul... | [
"I'd have to double check, though I am 90% sure they are two different brain areas. If you get a stroke in your native language area, you are supposed to be able to communicate in your second language. ",
"I believe the big difference between being multi-lingual and having a second language is just this. If yo... |
[
"What methods exist or are being researched for non-intrusive neural interfaces?"
] | [
false
] | I'm very interested in possible applications of high-quality neural interfaces, especially given fMRI studies and neural prosthetics. However, I don't know much about potential technologies (and current technologies) for non-invasive (i.e. non-surgical) neural interfaces. What methods exist, and which are being developed but look reasonably hopeful? | [
"So I'm assuming something you can carry around with you, as opposed to fMRI. In that case you're looking at EEG or, maybe ",
"fNIR (functional near-infrared spectroscopy)",
" although neither is terribly portable at the moment. ",
"EEG has a notoriously crummy signal to noise ratio, so you really need to be ... | [
"I like to draw people's attention to the spatial and temporal nature of signal processing in the brain, and that of the various methods used to measure it. Neurons in the cerebral cortex exist over its 250,000 mm",
" The signal changes on roughly a millisecond time scale every few tens of microns. HOWEVER, the s... | [
"I'm not sure I'm following your question exactly, but yes, there certainly are limits. For EEG, the signal at a channel is the result of the firing of many thousands of neurons. So you are measuring an aggregate signal. You're also getting coverage for the outermost cortical layers. See ",
"/u/JohnShaft",
" 's... |
[
"Why is plasma considered a different phase of matter than gas but metal isn't a different phase from solid?"
] | [
false
] | Plasma is basically a gas where the electrons aren't bound to the atoms, and the gas becomes chargeable and interacts with EM. A metal is a solid where the electrons float around in a "sea of electrons" and the solid becomes chargeable and interacts with EM. | [
"If you really want to go into defining phases in a rigorous way which applies in all cases, you need to go to a description that's too complicated for standard high school physics. IMO, the best way is using \"order parameters\" as described ",
"in this recent comment",
" by ",
"/u/IAmMe1",
". This include... | [
"Metal is a phase of matter! It's a type of solid. A sub-group.",
"Here's an example with animals: Let Metal = Elephants, Solid = Mammals, Plasma = Lizards. Then elephants are a type of mammal, and mammals and lizards are both types of animals. It would be like asking, \"Why are mammals a different type of an... | [
"Hmm I wanted this to be easier to answer than I am finding it to be. ",
"The heart of the problem is, I think, that the definition of a \"state of matter\" (which I think you mean by \"phase\"",
" ) is somewhat arbitrary. I am having trouble finding a useful scientific definition of \"state of matter\" at the... |
[
"How do astronomers catalog and organize the locations of stars/planets/asteroids in the sky?"
] | [
false
] | [deleted] | [
"The celestial sphere can be thought of as two dimensional, and so stars are located on it using either right ascension, a description of their distance from the prime celestial meridian, and declination, their distance from the celestial equator, or using azimuth and altitude, which obviously changes as the stars ... | [
"This is the first time I have seen it, but I think they use the ",
"Equatorial coordinate system",
". I'm basing this from that fact that star catalogues ",
"eg 1",
" use it as the input."
] | [
"The bottom line is we don't actually know the distance to stars. We think we do, and we're probably right, but we can't be sure. We've decided that certain classes of variable stars and supernovae have intrinsic brightness, and that by measuring the perceived brightness of those stars as seen from Earth we then de... |
[
"How do Computers manage Time so accurately?"
] | [
false
] | As I know so far, Computers have a system that increases a number by 1 every second and then convert that number into a format that we understand as a clock. How do computers know at what rate to increase this number. This is what I found when I looked for a definition of a second. How does a computer increase its time at the same rate as the defined second? Edit: thanks for downvoting | [
"A ",
"crystal oscillator",
" can be used to generate a very precise clock signal. The crystal naturally oscillates at a certain resonant frequency based on its material properties.",
"Since the frequency the crystal oscillates at is known, we can generate a clock from it. For example, if we know it's 16 MHz,... | [
"This guy pretty much nailed it on the head. ",
"To expand on this comment a bit:",
"crystal oscillators require electricity to work",
"the frequency of some oscillators are adjustable ",
"in order to keep time while the computer is unpowered, many computers have a small battery on the motherboard to help w... | [
"An interesting fact, most PCs and electronics use an oscillator clocked at 32,768 (2",
" Hertz or some other nice power of 2, so the timing circuitry is simpler. This way, the computer only needs a few stages of logic (flip-flops) that toggle every other clock cycle, and are linked so that every flip-flop is run... |
[
"If you get a face transplant, does it age?"
] | [
false
] | I debated asking this on , but I feel like there are more qualified people on here that can give me a good answer. I just watched video. A 41 year old got a 26 year old donor's face after an accident. Which made me wonder, would it ever age? | [
"Sure it would. Let's begin with normal aging which is usually a result of constant cell division decreasing the ends of chromosomes (telomeres). Once they get clipped enough, cells should stop dividing. Sometimes they do (senscence) sometimes they don't (cancer). There's also our frenemy oxygen! We need it to m... | [
"Is it really possible to live 15 years with no problem and then suddenly reject it ?"
] | [
"I support all you have said",
"I would also add that scar tissue and extra cellular matrix (ECM) add to a lot of what we think of as ageing. In this case, the transplant would age normally if not faster due to donor-host interactions. "
] |
[
"How significant is the genetic difference between the Northern and the Southern White Rhino?"
] | [
false
] | With the last male Northern White Rhino dying today, and only two females left, chances for survival of the northern 'half' of this species is pretty much 0. Apperently they have enough sperm to keep the two remaining ladies getting pregnant, but it is not that straight forward of course. To my surprise however, I read that there are thousands of their Southern counterparts left. I don't have a clue about the differences between the two though. Although the reasons they are still around might be really interesting, I am more interested in the biological difference between north and south. Could 'we' rejuvinate the northern species by using their southern brethren? How different are they? | [
"The Northern and Southern once though of as subspecies (like different breeds of domestic dogs) are believed to be of different species entirely. DNA evaluation shows it is an evolutionary divergent lineage a million or so years ago. They are similar in that they both have wide mouths as they are both grazers (whe... | [
"Just wanted to mention to those interested that San Diego Zoo institute for conservation research has large ongoing research projects regarding northern white rhinos. There are sperm and eggs banked in their frozen zoo from previous northern whites, plans to use southern whites potentially as surrogates for implan... | [
"Thus far, attempts to cross-breed them have been unsuccessful. To be fair, Sudan was too elderly to survive mating pretty soon after his transplant to Ol Pejeta, and one of the female northern whites has a bad hip and the other has ovarian cysts, so the opportunities to event attempt natural crosses were slim. (I ... |
[
"Can diverged species converge once again and breed if given enough generations?"
] | [
false
] | Could a group of organisms from the same species be isolated so they diverged and formed a new species (and thus no longer be able to breed with one another), then be reintroduced and reproduce once again? Given an unlimited number of generations and resources. Also is there any cases of this in history? Or is it more likely that once you split on the old family tree there's no going back? | [
"Theoretically speaking, no. By definition, species are populations that have diverged to the point where they can no longer interbreed (as your question suggested). This is due to the evolution of reproductive barriers, either prezygotic (meaning the two species no longer recognize each other as potential mates,... | [
"Theoretically it IS possible but practically its impossible. Technically, a set of step-wise changes (i.e. one mutation event followed by another) connects any two divergent species. The same set of mutations in reverse will bring any two species back into the zone of genetic compatibility.",
"In reality (nature... | [
"This is probably relevant: ",
"Ring species"
] |
[
"What exactly causes particles to produce a magnetic field?"
] | [
false
] | I know what a magnetic field is, and how magnetic fields interact with each other, but I'm not sure on what actually causes them in the first place. | [
"You naturally get magnetic fields in two ways:",
"You have current, e.g moving charges.",
"You have a fundamental magnetic dipole, e.g charged particles with spin (otherwise known as fundamental angular momentum).",
"You can make also make dipoles out of current loops (method 1.) but these are distinct from ... | [
"(since i don't see that you mentioned it): time-dependent electric fields also produce magnetic fields."
] | [
"My bad! This is essential for the magnetic field produced by light. In my head I was just thinking about charged sources!"
] |
[
"Why do we have a single, globally standard system for time but not other units of measurement?"
] | [
false
] | I was wondering where to ask this as I would like an answer. I mean, I know that time is linked to the movement of the earth around the sun but at the same time it's weird to think that it developed differently than temperature or weight or what have you. | [
"There is far more pressure for a standardized time than for standardized length or volume (and so on) measurements.",
"First, measurement of time is a bit less arbitrary than measurements of other things. A day is a day for everyone on earth. How you divide up a day is arbitrary but you still have a benchmark ... | [
"First, there are plenty of other units of measurements that are globally standard. For example, electric potential is always measured in volts, everywhere in the world.",
"Second, I think a large part of it is because time measurement leaves very few tangible artifacts (other than clocks). Once you spec a physic... | [
"That wasn't the question. I think he wants to ask why the standard measurement of time is universally accepted. There are plenty of other nations that had their own standard systems of other measurements prior to this last century."
] |
[
"Can something burn totally outside the visible spectrum?"
] | [
false
] | I'm wondering if there could be, for example, a fire that primarily radiates microwaves, or radio waves, or something of that nature. Most fire (or all, as far as I know) radiates in the infrared and visible spectrums. Could a fire exist entirely outside of those? | [
"Sure. And it is actually not that exceptional. Methanol is a highly desirable fuel for automobiles, but it has a major drawback that methanol flames are more or less completely invisible.",
"Here's a video of a methanol fire demonstrating the difficulty: ",
"https://www.youtube.com/watch?v=MnDX4FpDAzQ"
] | [
"Blackbody radiation can make UV rays easily. That chart shows what the radiation ",
" like, but that says nothing about the components of the radiation that are outside the visible spectrum, only the distribution within it. By Wien's displacement law you can make the frequency distribution peak at arbitrarily hi... | [
"They used and still use pure methanol in racing. But there are better fuels then methanol (nitromethan/ethanol) and it's hard to optimize engines on pure methanol, that's why in most of the cases blends are used. And not seeing the flame just seems not to be a problem.",
"Burning methanol isn't the big concern, ... |
[
"How come we humans can recognize a face from caricature drawings?"
] | [
false
] | As per the title, why can we recognize faces from caricature drawings with wildly exaggerated features? Takes this caricature drawing for instance: Even with the elongated bottom half of the face, with deformed lips and, stretched eyes and nose, we can tell who the the person in the drawing is. (I guess provided we've seen the actual real face before). Even with caricatures that exaggerates different features, we can still recognize it as the same person, as shown in these other caricature drawings: I wonder why is that, and thanks. | [
"As you could imagine, recognizing faces is a really important part of being a human. It's so important that we have a whole area of the brain dedicated to recognizing faces. It's called the fusiform face area and it's located on the ventral portion of the frontal cortex. To add to this, it's generally better to re... | [
"All the features of the face you recognize are there, just distorted. Some part of the face might be made bigger or smaller or flatter but all the parts have the same or similar layout color and form. The artist makes sure that is the case."
] | [
"Human memory is associative, meaning that we don't recall things in isolation but rather based on relationships with other items. The brains stores relationships between items as synaptic connections between neurons, which allow us to reconstruct patterns even when they are distorted by \"noise\" (in your example,... |
[
"Why are there no other Earth-like planets in our solar System?"
] | [
false
] | null | [
"It depends what you define as \"Earth-like\".",
"Mars, Mercury and Venus are \"terrestrial\" planets.",
"(What actually renders calling Martians extra-terrestrials pretty stupid...)"
] | [
"All of the planets in our solar system are essentially pretty unique, almost no two of them are quite alike. Venus and Mars aren't that different from earth though aside from the liquid water oceans that they lack. "
] | [
"Well Mars is a lot smaller than the earth, and I was wondering why it has no magnetic field to shield it?"
] |
[
"Could chemoautotrophic bacteria live in the hostile environments of another planet?"
] | [
false
] | Not entirely sure if this is the place to ask this question, but I was recently watching on Vimeo, and got curious. Bacteria have been known to thrive in some of the most hostile places on earth. Places where we don't think life could possibly exist because of lack of oxygen, light, and other things deemed necessary for life, yet they still do. So I was wondering, if it would be possible for bacteria that use nitrogen as an energy source to survive in other planets with high levels of radiation and toxic gases. | [
"The discovery of extremophile organisms like bacteria has certainly broadened our understanding of life, and the sheer strangeness and lengths it can go and survive.",
"So, the answer is yes. There definitely ",
" be organisms on other planets, even those that we might have traditionally thought of as being to... | [
"'Survive' is too weak a term. A number of extremophiles don't just survive, they thrive and live in these environments. ",
"It's true that we might not have evidence that abiogenesis could occur in harsher environments--but then, we don't really have that great of grasp of how it might occur under what we consid... | [
"We discovered some organisms CAN survive, not that abiogenesis can occur in such hostile enviroments."
] |
[
"Are there any moons we know of that rotate the planet at the same rate that the planet spins?"
] | [
false
] | If the rotation of the moon/rotating object matched the planet's rotation in terms of degrees, it would always be visible. Similar to how one side of the moon is always pointing towards earth. I was wondering if there is a planet where one spot on the planet always sees the moon at the same point in the sky? | [
"There is no planet like this, but ",
"Pluto",
" and its moon ",
"Charon",
" have this property. They are mutually ",
"tidally locked",
"."
] | [
"The term you're looking for is geosynchronous orbit. I don't know of any moons in such an orbit."
] | [
"As another commenter said, Pluto and Charon are mutually locked.",
"The important thing to note with this question - all planets with one moon will eventually end up in this situation given enough time. The Earth's rotation is continually slowing and eventually it's rotation will match the orbital period of the ... |
[
"Why is it hard to create tests for Covid19?"
] | [
false
] | null | [
"It's all three of those things. Various reagents have been in shortage at different points during this pandemic, and global demand is astronomic compared to the baseline. Many of the reagents are made in places that have been hard-hit (e.g. China) so it's required a retooling of the entire supply chain, not just s... | [
"RT-PCR instruments are reasonably expensive, in the 60K-80K region for the one's we buy depending if we get the diagnostic model or not. It's expensive enough that you only buy what you need. New ones were in very short supply, it took us a couple of months to get additional PCR instruments."
] | [
"The short answer is you need way more than just primers for a PCR test.",
"The early shortages were actually the enzymes, most assays use a single reaction to go from RNA to cDNA to PCR amplification. These are fairly specialized master mixes, and a lot of labs all use the same brand of this master mix which ran... |
[
"What will happen to our solar system during the years when the Milky Way & Andromeda galaxies collide?"
] | [
false
] | After watching several different simulations of the two when they collide, I can’t help but notice that some of the stars on the outer edges of their disk shape look like they get thrown out into deep space. Since our solar system is close to the outer edges of the Milky Way, will we be one of those unfortunate few that get launched out into deep space? Due to the massive distance till the next Galaxy at that point will we eventually be pulled back in? Or will we stay safely nestled within the colliding forces? Obviously we all will be long dead when this happens, but it’s our planet and I’m curious about its future. | [
"The odds of anything physically hitting us are very low. We could potentially lose some stars that we see now, and we would gain new visible (to the eye) stars as well. Even with the new stars, the chances of a supernova affecting us are pretty low as well."
] | [
"i'd venture to guess that our perspective of stars and constellations would be completely different... except for any bright galaxies."
] | [
"Yes, even a million years from now the stars in our sky will be different. The collision with the Andromeda Galaxy will start about 4000 million years from now.",
"To answer the OP, during the collision the Sun will swallow Mercury, Venus, and possibly Earth, and then collapse into a white dwarf. But this is onl... |
[
"How the hell do siphonophores work?"
] | [
false
] | In Siphonophores the organism is said to be composed of several distinct zooids. How are these zooids differentiated from a single genetically uniform zygote? How are they organised into distinct parts of the organism, do cells migrate or are all the zooids in different parts of the organism with no hybrid tissue? These fuckers blow my mind like what the heck are they doing with this outrageous multi-species shitshow that invariably ends up looking super cool, examples of or just the Portuguese man of war. How the frick do their embryos develop to form distinct zooids and how do these differ enough to be considered unique organisms rather than cell types. Is it just spooky epigenetic shit that merits then being classified into groups of zooids? Also side note on a specific siphonophore, how in the hell does Glaucus marginatus consume cnidocytes without being affected by the compounds released when they burst. Sorry for the overload of questions I am really enjoying these ocean lads rn. Any answers to anything is appreciated | [
"Siphonophores are a type of hydrozoan. Probably the best known hydrozoan is a ",
"hydra",
", a small freshwater animal that's similar to a sea anemone. I'm going to start off talking about hydras to explain the basics, since they are like a highly simplified siphonophore, and then move on to the real thing.... | [
"Siphonophores belong to class ",
"Hydrozoa",
", and are probably best understood by comparison to more \"typical\" hydroid colonies, such as ",
". Most hydrozoans have two main life stages: a stationary polyp stage and a swimming medusa (jellyfish) stage. Polyps feed and grow on the ocean floor like coral or... | [
"Thanks so much for your answer, I apologise for calling Glaucus marginatus as a siphonophore - this was the result of me misinterpreting the phrase “cryptic species complex” on the Glaucus Atlanticus Wikipedia page. Loved the video, thanks again for the help. "
] |
[
"What's the minimum size necessary a thing has to be to be seen from the ISS?"
] | [
false
] | null | [
"The human eye has an angular resolution of phi =1'=1/60° and the ISS has an average orbit altitude of z= 400 km. So the length l of the object in question is calculated as follows:\ntan(phi/2) = l/z so l=400km*tan(0.5')= 58 m. So theoretically, astronauts should be able to see football fields (as a dot). Note that... | [
"That's a lower bound. Atmospheric distortion will probably increase that. "
] | [
"That is awesome. Thanks for calculating it it looks complicated. For some reason I though you'd have to be way bigger to be seen. Huh. That's astounding thanks :)"
] |
[
"Can you compress a single molecule of a substance?"
] | [
false
] | [deleted] | [
"This is basically what happens in neutron stars. If you compress atoms hard enough, you can get them to the point where the orbital electrons are \"close\" enough to the nucleus to substantially increase the probability of electron capture. At this point, the electrons are able to combine with protons in the nucle... | [
"The chemical bonds that hold a molecule together are deformable. If you have a lone molecule that is flying towards a solid wall, with sufficient speed the molecule will fall apart and the fragments might undergo some chemical reaction with other molecules nearby.",
"A key part of chemical reactions involves bre... | [
" //",
"Whither the Pauli Exclusion Principle then?"
] |
[
"[All Fields] We (non-scientists) like to think of science as, well as an exact science. What is something that is contested in your field, and where do you stand on it?"
] | [
false
] | I guess pretty much what the headline implies: In your field of study, are there any points (even better if they're widely accepted, but still fiercely debated) that there still isn't a solid general consensus on? I don't so much mean "Evolution vs Intelligent Design", but more just "We're really not sure how $THING works, but this is what I think based on $EVIDENCE" | [
"In computer vision and machine learning absolutely everything is up for debate. We're not actually trying to describe something that already exists, but to build something new. This means that the only right answer is one which works today.",
"The Bayesians(probability represents prior knowledge of a model) fina... | [
"Tissue Engineering. Not really any debates there, but many people both inside and outside the field call it a \"voodoo science\". There aren't too many underlying principles, and its really just a bunch of labs trying to throw stuff at the wall to see what sticks. We take the principles of cell biology, and try to... | [
"There aren't too many underlying principles, and its really just a bunch of labs trying to throw stuff at the wall to see what sticks.",
"..Sounds like engineering alright :)"
] |
[
"Why do healing wounds itch?"
] | [
false
] | [deleted] | [
"There are two answers here that are each half of the whole answer. Healing causes itching in part because of some of the hormones that are signaled in the wound-healing pathway, and also because of mechanical deficiencies in scar tissue vs. normal tissue. ",
"Wound healing is a complex process, so I'm just gonn... | [
"Itch receptors are present in the skin. They are all thought to be sensitive to histamine, which is present during healing. The itch receptors are poorly studied, in part because they are C fibers (narrow axons) and are therefore difficult to isolate in electrophysiological experiments. ",
"See Torebjork et... | [
"IIRC from my physiology classes, it’s because scar tissue is tighter than regular tissue, and your skin has a lot of touch receptors. The stretching “tickles” them a bit. ",
"Secondly, especially with skin, the healing process is very dehydrating, and dry skin is also itchy. ",
"I could be wrong, but that’s ho... |
[
"When water/sweat is on our bodies, what property of water reacts with the air to cool us faster?"
] | [
false
] | null | [
"The water molecules have a distribution of energies, and the ones that are most energetic evaporate away, lowering the average energy of the molecules and thus the temperature."
] | [
"It's not reacting so much as evaporating. To evaporate it has to be at a higher temperature, which means it has to have more energy - that energy comes from your skin and since you then have less energy (in the form of heat) you cool down."
] | [
"You're asking about something called \"evaporative cooling\" which isn't unique to water (think of rubbing alcohol - much better at cooling the skin, but anyway...)",
"Water has ",
"a lot of special properties",
" and the relevant ones here are unusually high thermal conductivity and heat of vaporization.",
... |
[
"When a beta minus decay process turns a neutron into a proton and an electron, why does the electron get expelled from the nucleus?"
] | [
false
] | I know that Electrons are not found in the atomic nucleus, but why does it have to leave it, if it has been produced there? And a second one: can the newly formed electron be taken up by the electron shell of the same atom? | [
"Momentum conservation. ",
"A neutron at rest, decays into a proton, an electron and an anti-neutrino(electron variant). ",
"Since the anti-neutrino is ",
" massless, it carries away some percentage of energy off, and carries huge momentum. The proton and the electron soak up that momentum in the opposite dir... | [
"You're most likely looking at plots of the radial probability distribution, which is the density at radius r, summed over the surface of a sphere of radius r; i.e. it's been multiplied by 4πr",
" , so it's naturally zero if r=0. That plot tells you which radius the electron is most likely to be at, rather than w... | [
"So in principle, a slow beta electron might end up the shell of the atom where it has just been produced? "
] |
[
"How does melatonin work in the body, and what does it do?"
] | [
false
] | I'm particularly interested in the research being done on how melatonin prevents or treats cancer. | [
"Generally, melatonin works as an antioxidant. On the topic on preventing cancer, there was a study in 2001 that showed melatonin was able to prevent DNA damage in hamster kidneys. The article was focusing on a very specific type of DNA damage and then related these results to carcinogens.",
"Source",
"Edit: Fo... | [
"Hamster kidneys! Thanks, that actually gives me a place to start. :-)"
] | [
"what did i miss? when did melatonin stop being used solely as a sleep aid?"
] |
[
"What does CO2 actually do to the ozone layer?"
] | [
false
] | I have been doing some research and get varying answers so I figured I would try to ask some people smarter than me. So does CO2 help or hurt the ozone layer? Most mainstream articles talk about how it’s the “most dangerous greenhouse gas” and such, but yet I’ve also seen articles saying it is helping close the hole in the ozone by keeping nitrogen oxides from reacting with the O3. So which is true? Does it actually help or hurt | [
"CO2 has no effect on the ozone layer. The ozone layer is a layer of O3. The problem with CFC is the cloro. As in chlorine. A single chlorine atom can break down as many as 100,000 O3 molecules. CO2 is greenhouse gas. That means it allows visible light and UV to pass thru but reflects radiated heat. Like the glass ... | [
"Ozone ",
" 'help keep in heat' - as ",
"/u/Captain_Trips_Tx",
" said, ozone is a greenhouse gas like CO2. We quantify the amount of heat a greenhouse gas 'keeps in' through a metric called the ",
", and the radiative forcing of ozone in the present atmosphere is ~0.35 W/m",
" compared to ~1.8 W/m",
" f... | [
"I gotcha. Thanks for explaining!"
] |
[
"How does gravity affect light?"
] | [
false
] | null | [
"The source of gravity isn't just mass, it's the stress-energy tensor, which contains things like mass, energy, and momentum."
] | [
"What exactly is this \"stress-energy tensor\" if I may ask?"
] | [
"You can think of it as a 4x4 matrix which contains things like mass, energy, and momentum. And it has certain transformation properties under Lorentz transformations."
] |
[
"What's the fastest possible speed a human can potentially reach?"
] | [
false
] | We all know that world records get set every now and then, but is there eventually going to be a world record that can literally never be broken ever in a race? Will a human being under the perfect conditions ever be able to hit a speed that is the fastest possible ever? | [
"It depends very much on the limitations of the race. Are you talking fastest speed over, say, 100 meters on foot? A mile on a bicycle? Or strapped to whatever contraption someone can dream of to go fast?"
] | [
"Well I suppose it would be interesting to see what the predicted maximum would be for each event. But The article already posted seems to explain most of what I was wondering :)"
] | [
"The record for fastest speed ever achieved by a person is apparently held by the guys on Apollo 10. Figured it had to be something like that."
] |
[
"Once the Earth was formed into a planet, has the North Pole ever not been covered in ice?"
] | [
false
] | [deleted] | [
"Yes. In the beginning, pre-atmosphere, Earth had a very hot surface. It was essentially the fiery leftovers from the creation of the Earth. Even much later, when Earth was a more recognizable water-covered, atmospheric, life-harboring planet, there were still periods when the polar ice caps did not exist. Accordin... | [
"Also note that the continents we know didn't always have their current shape and position. There have been numerous supercontinents over the millions of years since Earth cooled enough for ice to form. There have been many times when there just wasn't any land AT the north pole to get covered in ice. ",
"There i... | [
"For much of Earth's history the poles were not covered in ice. We happen to be in an ",
"ice age now that began about 30 million years ago",
", but before that the poles were generally ice-free since the end of the last ice age, 260 million years ago.",
"https://en.wikipedia.org/wiki/Timeline_of_glaciation"
... |
[
"If the eye is opened during sleep will the brain still process the visual information?"
] | [
false
] | null | [
"No, and maybe!",
"OK. During sleep, particularly REM sleep, the ascending sensory pathways are shut down by strong inhibition. On the other hand, visual input provides a very strong drive to inhibit sleep. Enough light in the eyes, and you stand a good chance of waking up. However, lower amplitude visual inputs ... | [
"Yes. The pathways involve the PPT/LDT, reticular thalamus, and LGN. Yes, a coma involves shutting down these same pathways. So does persistent vegetative state (now politically correctly called unresponsive wakefulness syndrome). "
] | [
"the ascending sensory pathways are shut down by strong inhibition",
"Physically, what's happening when the visual pathway is \"shut down\"? Is there some spot where the optic nerve connects that gets a dump of some chemical that suppresses the neuron actions? I would imagine it needs to be fairly early in the vi... |
[
"My dad has early onset Alzheimer's, 23andme gives me a 2.0x risk of Alzheimer's. I'm 24, what's my game plan?"
] | [
false
] | null | [
"Lots of curry and spicy foods.",
"Alzheimer's is all but unheard of in India."
] | [
"Eh I'll stick with awesome food. If it's the water, you can move?"
] | [
"It wasnt about the water. I just took an example which was near to that food thing. I just wanted to show that you cant break down the whole cultural and medical environment of a counter/culture to food. It would be too easy :D \nBut anyway great food i can agree to that (but thats not on topic anymore)",
"Back ... |
[
"If I mix rubbing alcohol and water to lower the freezing point of water, will it take longer to thaw?"
] | [
false
] | I am about to make some ice packs for the cooler. I was going to use a mixture of water and rubbing alcohol to lower the freezing point and make colder/flexible ice packs that do not freeze completely. Will these ice packs stay colder longer that a straight frozen water ice pack will? If not, am I better off using straight water or another mixture? | [
"My intuition says yes, because adding alcohol lowers the freezing point of water, and the specific heat of liquid water (4.187 J/gK) is higher than that of solid ice (2.108 J/gK)."
] | [
"You should keep in mind however that the specific heat of isopropanol is much lower than that of water (2.604 J/gK). Perhaps more importantly though, the heat of fusion of water is 333 J/g, so by decreasing the amount of frozen water, you're decreasing the amount of energy that needs to go into phase change befor... | [
"You're absolutely right - the phase transition dominates the energy transfer, so it's better to use a substance with the highest possible heat of fusion, such as pure water. The wikipedia page on ",
"ice packs",
" claims that the substance used in ice packs is typically water or a water gel with additives to p... |
[
"Why does the far side of the moon have so many small craters while the near side has several very large ones?"
] | [
false
] | When I look at images of the moon, the side which always faces the earth has several very large craters but the side that faces away from us is pockmarked with much smaller ones. This leads me to think that the far side of the moon has suffered many tiny impacts while the near side has suffered fewer but much larger impacts. Is that the case? If so, why? Is the Earth's gravity affecting the way that meteors strike the moon? Or this an illusion, because the far side getting struck by large impacts but these large craters are getting erased by many smaller impacts (While they do not as commonly strike the near side, thanks to Earth's protection). These are just a couple of rough guesses, clearly I don't have a lot of knowledge about this. | [
"This is a function of the difference in the thickness of the crust between the farside and nearside of the Moon.",
"The frequency and size of impacts on the Moon is actually roughly equal between the two sides. In fact, the largest impact basin on the Moon is on the far side, ",
"Aitken Basin",
", the huge d... | [
"You have to think of it in terms of ",
" pull. ",
"The whole Earth is being pulled by the Moon, determining its orbit in space. The near side is being pulled a little more than average so there's a bulge on that side as it tries to be in a nearer, faster orbit. On the other hand, the far side is being pulled a... | [
"Again, ",
"that's incorrect",
". The tidal force would pull the lava to both the nearside and farside of the moon, for the same reason that there are two \"high tides\" at any moment on Earth."
] |
[
"Is it theoretically possible to assemble fused subatomic particles into macro-scale 3-dimensional objects?"
] | [
false
] | I know a little bit about some of the concepts of quantum physics - enough to know that the strong nuclear force is really strong. I was reading an article about nuclear fusion when it dawned on me that if it were possible to fuse protons or neutrons of the like into chains or rings, creating a new element with spatial structure instead of just chemical differentiation from the other elements, that element could be used as a new rigid material, the strength of which would be unparalleled by anything humans have created thus far. I just want to know if it's possible or not based on current theories in the field. | [
"I love this question, as it is basically trying to get organic chemistry in nucleii. Complex molecules that are not simply as compact as they can get like a crystal depend on delicately balanced attractive and repulsive forces. Neutral atoms tend to generally repel one another when the electron shells overlap, but... | [
"The simple problems are that firstly neutrons are so strongly attracted to each other they would clump rather than form rings.",
"Secondly neutrons weigh and therefore have more energy than a free proton and electron. So any clump of neutrons will begin to decay into protons until the repulsive force of the prot... | [
"If you're talking only using protons and neutrons, wouldn't you also be creating something amazingly dense like a neutron star? Your material would be too heavy to move."
] |
[
"How did early humans clean themselves?"
] | [
false
] | null | [
"Also, did they wipe their butts after pooping? Or just poop and go?"
] | [
"Well, it's not really hard to do. Block one nostril and exhale very forcefully. Basically what you do when blowing your nose with a handkerchief but without that and a bit more forcefully because it gets messy otherwise."
] | [
"When out on patrol, Roman soldiers would just go to the toilet wherever they were. Back at the fort, they shared communal toilet spaces, such as can be found at Hadrian's Wall. The toilets had their own plumbing and sewers, sometimes using water from bath houses to flush them.",
"http://www.bbc.co.uk/learningzon... |
[
"Why do my calculator and Wolfram Alpha disagree on a negative number with a fractional exponent?"
] | [
false
] | When calculating something like (-2) my TI calculator gives a (real) value of about -1.515, but when I ask Wolfram Alpha for the it gives an imaginary number, but with the same magnitude as what the calculator gives. Why is there a difference, and is one of them wrong? | [
"The answer is right in the page. Over the complex numbers a complex number (note real numbers are complex numbers with 0 imaginary part) has n n",
" roots.",
"http://i.imgur.com/6NgioRk.png"
] | [
"Yes. That's basically it. There are deeper reasons, but in essence it's because (-1)",
" doesn't have a real solution. ",
"The slightly deeper reason you can see by looking at the roots of (-2)",
" plotted in the complex plane: ",
"http://imgur.com/HmngYU8",
"As you can see they are 4 symmetric points ac... | [
"It seems you have a satisfactory answer to your question already, but I just want to point out on the three TI calculators I tried out (-2)",
" will be interpreted by the machine as (-2",
" )/5. The parenthesis really need to go around the exponent, but it's never a bad idea to just put them around everything ... |
[
"How can V8 vegetable juice go a year without expiring?"
] | [
false
] | I have a bottle of V8 that says it expires Jan 2014. I've actually had it for about two months and just finished it. What is it that allows it to last so long? | [
"What's this totally incorrect and potentially-hazardous nonsense? ",
" of 'bad things' can grow in food under anaerobic conditions - not least ",
", which causes botulism. V8 juice holds because it's been pasteurized, which is when you heat up sealed containers of food to kill the bacteria in them. ",
"See t... | [
"What's this totally incorrect and potentially-hazardous nonsense? ",
" of 'bad things' can grow in food under anaerobic conditions - not least ",
", which causes botulism. V8 juice holds because it's been pasteurized, which is when you heat up sealed containers of food to kill the bacteria in them. ",
"See t... | [
"Usually if the expiration date is affected by breaking the seal, they list the second date, right? ",
"Not necessarily, no. It ",
" doesn't hold as long once it's been opened. It depends entirely on the product but it's typically days to a few weeks. Two ",
" sounds like a very long time, it's possible the V... |
[
"How would our trajectories differ between interplanetary travel and interstellar travel?"
] | [
false
] | I understand the basics of changing a space crafts orbit to reach "nearby" destinations, such as the moon or Mars, or any body in our solar system. But across the enormous distances between star systems, how would the trajectory of a spacecraft look? Would it be relatively straight-lined point-to-point, or adjusting our orbit the exact same we currently do, but on a galactic scale? This is of course assuming that we use spacecraft that work like those we have today, nothing futuristic using warp or FTL or anything like that | [
"One thing others didn't mention is how the navigation requirements for the spacecraft are going to change.",
"Currently, if something is in orbit around the earth, we can use GPS or ground based optical measurements of the object to determine its current orbit. If we're near some other celestial body (such as O... | [
"If you want to reach Proxima Centauri, the nearest star, in less than 10,000 years then you need to have a speed of at least ~100 km/s (both relative to us and Proxima Centauri, doesn't make a big difference).",
"During that time the rest of the galaxy accelerates the spacecraft by ~100 m/s, so that's already a ... | [
"Ok, so, low earth orbit ('LEO') is typically 7.8 km/s. We typically have a delta-V of +4.2km/s to throw something at Mars from LEO, then -1.4km/s to circularize/slow down to Mars orbit on arrival, for (4.2 + 1.4 = ) 5.6 km/s of delta-V total from LEO. That gets you to Mars in ",
" btw.",
"Meanwhile, Mars is or... |
[
"Is there ever anything going on that is not a chemical reaction?"
] | [
false
] | Force maybe? | [
"Yeah, seeing as a chemical reaction is defined as \"a process that involves rearrangement of the molecular or ionic structure of a substance\" everything that doesn't do that is not a chemical reaction. E.g. boiling water and melting ice involve rearrangement of the spacing between water molecules yet the water mo... | [
"I am presuming here you mean bond breaking or bond formation as a chemical reaction. All nuclear reactions, like radioactivity, do not qualify as chemical reactions. Sound waves are not a chemical reaction, they are gas molecules undergoing pressure waves, no bond formation or breaking involved at all. Phase tr... | [
"Phase transitions involve breaking/forming of intermolecular bonds, nuclear bonds are broken/formed during nuclear events. Just to clarify. "
] |
[
"If fire goes from red to yellow to blue to white, matching with the frequency of light why do we not (or very rarely see) green natural fire?"
] | [
false
] | I’ve seen multiple fire colours from natural heat and not copper, strontium or others. So why is it that we rarely (or don’t) see green fire? | [
"This is an excellent question! ",
"The short explanation is: it's just the way the universe works. ",
"The medium explanation is: ",
"Planks' law",
" governs the spectral density of electromagnetic radiation emitted from a ",
"black body",
". As the temperature of a body increases from absolute zero... | [
"Actually a very good explanation. It’s why we don’t see green stars, too"
] | [
"/u/Farnswirth",
"'s answer refers exclusively to the blackbody radiation of a medium, which accounts for the vast majority of the flame colors we are familiar with, however the flame can also assume a specific color through the bright emission of spectrum lines from excitable atoms, which can happen at any frequ... |
[
"Is it possible to have an \"opaque\" laser?"
] | [
false
] | [deleted] | [
"Photons are uncharged bosons. As such, they can occupy the same state and can pass through each other without interacting. In order for a light beam to be opaque, another light beam propagating through the same space as the original light beam would have to scatter off or be absorbed by the original beam. This doe... | [
"Based on photons alone, not for reasonable lasers. If you focus enough light in one place, it's theoretically possible to create a ",
"kugelblitz.",
" However, it is possible, within an atmosphere, to create a laser that ionizes the air into plasma, which is generally opaque to electromagnetic radiation below ... | [
"Also, in theory, if the photon density gets high enough, it could form a black hole.",
"I don't see how that would work. The energy in the beam has to come from the laser medium, which would have been a black hole already. Even if you try to get this effect by firing multiple lasers at one point, I still don't s... |
[
"Which is heavier, ice or water?"
] | [
false
] | null | [
"Assuming \"amount\" means either mass or # of molecules then they are the same weight. If you freeze a certain amount of water it will have exactly the same mass in both states but more volume in the ice state (lower density). Both samples would have an identical number of water molecules as you don't form or de... | [
"So changing states doesn't effect the weight, because the matter doesn't physically change? Does this extend to gasses as well? Would boiling a kettle of water but \"catching\" the steam result in the same amount of moisture, just displaced differently then?"
] | [
"Careful with the terminology. A phase change is a physical change but not a chemical one. If there is no chemical change then all the molecules on one side are exactly the same as the other, just with some different energy or state.",
"Also, even with a chemical change mass is always conserved, so as long as y... |
[
"Does the shape of a lightning bolt have an effect on the sound of the thunder?"
] | [
false
] | Primarily if we were to graph a bolt of lightning and compare it the the levels recorded to that associated roll of thunder, would we see a correlation? What if the sound were graphed in a 3D space? How different is a forked lighting bolts' thunder VS the thunder from a bolt with no forks? Does this make sense? | [
"I have issue with your perfectly straight lightning bolt. Certainly if it were close to you and straight, the sound would be one big boom, but given the size of lightning bolts, the closest part of the \"line\" would reach your ears perceptibly sooner than the furthest.",
"To get a single BOOM you'd need a circu... | [
"I have issue with your perfectly straight lightning bolt. Certainly if it were close to you and straight, the sound would be one big boom, but given the size of lightning bolts, the closest part of the \"line\" would reach your ears perceptibly sooner than the furthest.",
"To get a single BOOM you'd need a circu... | [
"Resoning",
" \nFork lightning is the actual lightning. Sheet lightning is actually layers of clouds illuminated by hidden fork lightning. ",
"This is the closest I could get between the difference between the sound of forked and sheet lightning. I think they maybe a muffling effect due to the clouds, however, ... |
[
"Why don't airliners pre-rotate their wheels prior to landing?"
] | [
false
] | It would seem to me that landings would be a lot smoother if the plane's wheel were already turning at a speed that roughly matches the aircraft's landing speed, rather than the wheels having to go from 0 to 200 kmph at the instant of making contact with the ground. Or do they already do this? | [
"I work in the aircraft wheel and brake industry. First, a landing doesn't leave kgs of rubber on the runway... only a few grams. Second, aircraft are very weight conscious, and anything not necessary costs a lot of money in fuel. Spinning up the tires before landing would require some mechanism (motors, fins, g... | [
"Also, aircaft almost never land perfectly straight due to crosswinds - this means that some sliding is necessary at touchdown; pre-rotating wheels would reduce this initial slip on the runway and add unwanted lateral forces to the undercarriage."
] | [
"Okay. Looked it up and it seems I exagerated a little from my memory. BUT this site ",
"link",
" says that it is half a kg per landing. ",
"Specialized rubber-removing machines are actually operating regularly, although maybe not daily. Source: I work at an airport.",
"This article explains it too: ",
"l... |
[
"Why haven't we weaponized lasers to a point that they could just blast a hole in any human from a long distance?"
] | [
false
] | I know there are extremely powerful lasers used in surgery or industry. Why hasn't the DoD created some weapon that would allow a novice shooter to blow a hole in someone from two football fields away? No gun shot. No gravity or wind carrying the bullet away from the target. Drone killings would be simpler and cause little to no collateral damage. Assassinations would be as easy as just having line of sight. | [
"There's two physical reasons for the difficulty. One is the power source and the other one is diffraction/scattering. The surgery (and machining) lasers have a very significant power supply and close to the target. In order to get much of an effect, you need a lot of optical energy in a small location (i.e. a h... | [
"Herrsmith laid out the technical limitations very well, but here's the reason why this isn't even a very feasible idea:",
"Cauterizing a 12.7mm/.50cal hole in someone's body is no where near as catastrophic as having a 50g piece of metal tear through your body at 3000 ft/s. Many of the reasons why lasers are use... | [
"The answer is simple. Converting stored electrical energy into light energy is extremely inefficient. An 11 watt IR laser could take several hundred watts of power to operate. That's a lot of wasted energy, usually in the form of heat."
] |
[
"Can quantum entanglement / other phenomena of QM be explained by a higher dimension?"
] | [
false
] | Hey guys, excuse my science speak as I am a layman, I was just wondering, if there was indeed a dimension that encapsulates/ is parallel to our space time, that is not restricted to space/time, could that dimension explain spooky action at a distance? Like the particles would be 'connected' through that higher dimension. | [
"I would say it ",
" spooky action at a distance, and it's not well understood at all. But I agree that higher dimensions wouldn't solve any of the remaining questions."
] | [
"Quantum entanglement is not a \"spooky action at a distance.\" It's very well understood and doesn't require higher dimensions, nor would the addition of higher dimensions actually help explain it."
] | [
"Quantum mechanics is local.",
"It might be. We have no conclusive proof either way. But nobody actually working in this field believes that QM is really local. ",
"Your example wouldn't change that in any way even if it was correct. But it's not, because the correlation will be there even if you don't compare ... |
[
"How far across a genus or species do allergies go?"
] | [
false
] | Such as a person being allergic to a dog. How far from canis lupus familiaris is would you need to go (if at all) to not be allergic to one? | [
"As ",
"/u/ketralnis",
" says, the allergy is to a specific substance (usually a protein) produced by the source of your allergy. If any other organism (including ",
"!) produces a protein with similar structure to the one you are allergic to then you will also have an allergic response when exposed to it. Lo... | [
"And so is that how people can have multiple allergies to seemingly different organisms? Because they happen to contain some type of protein of similar structure that their body rejects or reacts to?"
] | [
"That is a possible factor, however it is more likely that those individuals are predisposed to allergic responses and are actually making antibodies to different proteins produced by each of the organisms they are allergic to. Genetic or environmental factors can result in a tendency to produce IgE antibodies (ass... |
[
"Why are transistors so crucial to modern technology?"
] | [
false
] | [deleted] | [
"Solid state devices was not my favorite class, but this what I remember. They can hold a charge, being on/off or 0/1, which is what computers understand. They also amplify voltage fairly linearly in a certain input range. Being a lot smaller than old vacuum tubes, so we can have more \"brains\" in a computer tha... | [
"Transistors don't generally hold a charge. A controlling voltage must be maintained. Flash memory transistors do use a second gate to hold a charge but that is something extra."
] | [
"I thought that was a bad way to word it, so I googled, and other people used it so I thought it was okay. Curse you, internet. I remember ram having to refresh every .000000001 seconds or something. That class was not my favorite, and it was many moons ago."
] |
[
"For the universe, if the Big Bang were 12:00:00 on Jan 1, and the theorized Heat Death were 11:59:59 on Dec 31, what day/time is it now?"
] | [
false
] | [deleted] | [
"So the \"heat death\" isn't a sudden event - it's a gradual process of everything drifting away from each other. But we can look at some of the events that will happen along the way that could mark the \"end\" or ",
". For comparison, the universe is about 13 billion years old right now.",
"After about 100 bil... | [
"Keep in mind that recorded history only goes back 0.1 milliseconds on this scale, and anatomically modern Homo Sapiens only emerged ~.01 seconds before that. The dinosaurs went extinct 2 seconds ago.",
"Human civilization has only been around for the tiniest fraction of the age of our universe, and our universe ... | [
"Keep in mind that recorded history only goes back 0.1 milliseconds on this scale, and anatomically modern Homo Sapiens only emerged ~.01 seconds before that. The dinosaurs went extinct 2 seconds ago.",
"Human civilization has only been around for the tiniest fraction of the age of our universe, and our universe ... |
[
"How does the new idea of a cyclical universe fit into thermodynamics?"
] | [
false
] | I can only assume that the recent idea of cyclical universe has been thought through much more than I could ever dream of doing. I have a grasp of thermodynamics, namely that entropy is always decreasing, but the idea of a cyclical universe doesn't seem to fit into this. How can the universe end with complete disorder, so much so that there is effectively nothing in it, and then "reset" back to a "zero" entropy and begin again? Like I said, I have a grasp on thermodynamics, but I am probably way off base on a couple of my premises above. The bottom line is that I'd like a better understanding of what the new idea of the universe says that probably can't be described in a short internet article that spends time talking about the old theory. | [
"This does not conflict with thermodynamics. Entropy is only a measure of probability, which is to say that higher entropy states are more probable than others. The second law is \"almost always\" true in that the universe is more likely to transition to a more probable state than a less probable state. It turns... | [
"An interesting thing to consider: a black hole is actually the highest entropy state possible in the universe, because from the perspective of someone looking at the hole, all of the microscopic states of the matter that fell in can only be described by three macroscopic parameters (mass, rotation and charge). So... | [
"Also, this is all complicated somewhat by things such as Hawking radiation, the possibility that the universe will expand faster than gravity can pull it together indefinitely, as well as the fact that we don't know whether information in black holes is truly \"lost\" forever or not.",
"As t -> infinite black ho... |
[
"Why are saline solution injections used as a placebo in vaccine trials?"
] | [
false
] | I’ve been reading up on how vaccine testing works recently, and I noticed that trials that use placebos often choose saline solution. Why is saline solution the most common choice instead of pure water or another alternative? | [
"It mostly resembles the osmolarity of human fluid and is therefore the most 'neutral' for the human body. This is exactly what you need from a placebo, something that does next to nothing when injected in the body, where as pure water would activate different mechanisms in the body to compensate for the loss of os... | [
"Edit: 0.9% Sodium Chloride or “normal saline” is what they refer to as an “isotonic crystalloid.” That means that the osmolarity most closely matches a healthy human body and therefore does less cell damage. Hypotonic solutions and hypertonic solutions move to areas of higher and lower concentrations (respectiv... | [
"0.9% Sodium Chloride or “normal saline” is what they refer to as an “isotonic crystalloid.”",
"As a materials scientist, I was interested in the origin of \"crystalloid\". The solution itself is not crystalline. The correctly complete term \"crystalloid fluid\" is apparently intended to draw a distinction from \... |
[
"Would it be effective to remove all nonfunctional junk DNA from human/animal genome?"
] | [
false
] | Well, apart from making it incompatible with his own species. According to several articles I've read, big part of human genome is not relevant to any proteins or any other mechanism in our organism. | [
"There's no such thing as junk DNA, that term has fallen out of favor. ",
"There is coding DNA and non-coding DNA (formerly \"junk\"). We're learning that much non-coding DNA may have a structural or regulatory role that we are unaware of.",
"That being said, there's a lot of DNA that can be done away with, b... | [
"There are people more qualified to answer this, but here is one answer.",
"First, the term \"junk DNA\" is becoming a bit of a lesson for biologists. It's a poor term. More and more functions are being found all the time. We can describe regions of DNA as one of the following: gene, gene regulator (non-coding bu... | [
"To be clear in all of this, there is a fundamental lack to terminological consistency among biologists/geneticists when it comes to talking about genomes and about the role of DNA within those genomes.",
"DNA is never ",
" \"coding\". DNA servs as a ",
" for RNA (which itself can code) but DNA never ",
" ... |
[
"Is the heat generated by an internal combustion engine mainly from the actual burning of the fuel or from friction within the engine?"
] | [
false
] | I am thinking about your average car, and how the heat is generated. Bored driving one day looking at the temperature dial the question came to mind. | [
"Much of the engine's high temperature comes from simply burning that gasoline. The reaction takes place at a high temperature and of course it heats up various engine parts.",
"Then, some fuel energy is transformed into mechanical energy and moves various parts of the motor. Due to friction, some of this mechani... | [
"I think the question is really, how hot would the engine get if it was being powered by another engine, not fuel?"
] | [
"It wouldn't get hot. Friction in the engine is very minimal. There is proper oil lubrication everywhere to ensure this."
] |
[
"Hydrochloric Acid and Tin Foil?"
] | [
false
] | I have been acid washing sediment samples with a 10% HCl solution and accidentally used 100% HCl on a few of them, which isn't a big deal, it's just to wash away the carbonates. However, to speed up the process we put them into a hot water bath, upon coming back 3 hours later, I found the tin foil over the samples with the 100% HCl eroded, with yellowish scum over top of the samples My question is, if this new substance, which I think is AlCl3?, gets into my sample, will it just disolve into the solution and get washed out when I rinse my sample with DI water until it is no longer acidic? or will there be extra aluminum in my sample, I need to test for %Corg and %N so I dont want my readings messed, thank you to anyone who can help me with this | [
"100 percent hydrogen chloride is a gas, I am guessing you mean some 30-36 percent solution diluted by a 1/9 factor. The 30-36 percent stuff is common because this is the amount that can reasonably be dissolved in water without significant off-gassing. Heating it drove hydrogen chloride gas off the solution, along ... | [
"You did indeed form AlCl3. Luckily, it's fully soluble in water. (Only Ag",
" , Pb",
" , Cu",
" , and Hg2",
" are insoluble). If you wash it thoroughly, you should be fine."
] | [
"Thank you! I will rinse them about 20x just to be certain"
] |
[
"What did Americans sound like in the 1700s/ early 1800s?"
] | [
false
] | Is this even possible to figure out ? | [
"Linguist chiming in here. These sort of questions are fraught with problems from the get go. First you have to isolate what area of the USA your are referring to. Within the original colonies you would have had more than one linguistic group, but there is usually a dominant one. In Labrador there are people curren... | [
"Mark Liberman and Geoff Pullum of ",
"Language Log",
" have mentioned on multiple occasions that linguistics seems more vulnerable than other fields to baseless speculation and urban legend being taken as fact (see the case of the ",
"\"nasal drawl\"",
", or the ",
"\"Obama pronouns\"",
" meme which ci... | [
"Sadly the morpheme breakup is shes-hat-shit, for those who do not know the IPA it sounds like \"shay-hat-shoe\""
] |
[
"When I disinfect a cut with alcohol am I killing \"good\" bacteria that would speed the healing process?"
] | [
false
] | Assume the cut has a relatively low risk of infection. | [
"As far as I have seen there are no bacteria that help to speed wound healing. However you are killing the fibroblasts that are trying to heal the wound and thereby topical antiseptics slow wound healing. The data is fairly poor but the only topical antiseptic that can be diluted to a point that it kills bacteria b... | [
"This touches upon a common misconception.",
"We are frequently told that our body is swarming with bacteria - \"good\" bacteria, which is true but the misconception is that they are everywhere in our body. In reality our body, once you go under its surface, in normal circumstances is sterile. Our gastrointestin... | [
"While many species of bacteria live in your body that are beneficial to you, none live inside the sterile environment below your skin. Billions of bacterial cells live on the outside of your skin and have several functions, i.e. outcompeting non-native bacteria, or replenishing your gut biome, but are actually qu... |
[
"How can you detect details of a distant planet like Kepler 22?"
] | [
false
] | How do we know Kepler 22 is Earth like? How can we detect anything about a planet that is 600 light years away? There's no way we could detect life on a distant planet with our current technology right? | [
"Since this is where the top link goes to, here are a few other questions that have been posted.",
"Could humans live on a planet with gravity 2.4x (potentially Kepler 22b) Earth's?",
"If kepler 22b is 2.5 times the size of Earth would theoretical humans living on the planet have to be 2.5 times the size of Ear... | [
"The planet reflects its star's light like our moon reflects the sun's light. When the planet goes behind the sun, its reflected light is hidden behind the sun and so it is removed from the sum of light that is directed towards us."
] | [
"Transits (planets crossing in front of their parent star) are detected by observing dimming of the light emitted from the star. By noting the magnitude and duration of the dimming in comparison to the mass of the star, you can deduce both the planet's size and orbit, and consequently know how much solar radiation... |
[
"What would happen if you took a laxative and an anti-diarrheal at the same time?"
] | [
false
] | [deleted] | [
"I'm not versed on the subject; I'm merely providing guidance based on intuition and relevant Wikipedia knowledge.",
"Laxatives fall into several categories, of which I'll list just a few examples:",
"Bulking agents (those dietary fibers you hear about, among other things) allow your stool to bulk up and retain... | [
"Why don't you try it yourself and report back the results. For science."
] | [
"One of them will win. "
] |
[
"how do the laws of of physics break down in a black hole"
] | [
false
] | null | [
"Why does that happen?"
] | [
"Why does that happen?"
] | [
"So we just dont know?"
] |
[
"How does shampoo/conditioner work?"
] | [
false
] | It's just one of those things that everyone uses but nobody understands how it works. Thoughts? | [
"The purpose of shampoo is to wash and remove dirt, oil buildup and other adsorbed compounds (e.g. smoke) that you don't want in your hair. Conditioner is used to change the properties of your hair, usually in some favorable way. They are separate products, because in some cases they counter each other in purpose. ... | [
"Take a look at the ingredients on your shampoo bottle. Most likely you will see Sodium Dodecyl Sulfate or Sodium Laureth Sulfate or one of their derivatives. ",
"These compounds are surfactants. Surfactants have heads that are attracted to polar subtances like water and tails that are attracted to nonpolar subst... | [
"So it's essentially the same principle as soap acting on hydrophobic compounds, except on my head. Interesting!"
] |
[
"Why is it favorable to have a dominant hand or 'side' over ambidexterity?"
] | [
false
] | null | [
"It's a reasonable story, but is there any specific evidence that that explanation accounts for handedness? One could wave their arms and offer such an explanation for a lot of human behavior."
] | [
"It's a reasonable story, but is there any specific evidence that that explanation accounts for handedness? One could wave their arms and offer such an explanation for a lot of human behavior."
] | [
"I think this is a topic up for debate! ",
"\"More than 90% of the human population is right-handed, and biased hand use is also observed in non-human primates and other mammals. But whether there is a dominant preference for one hand at a population level is still debatable. What has made most humans right-hande... |
[
"why does a liquid always have an equal amount of positively and negatively charged molecules?"
] | [
false
] | also, is the same true for a plasma? | [
"They don't always. But a charge imbalance implies a voltage difference and thus an electrical field, so it's not easy to keep charged particles from moving in response."
] | [
"Not just theoretically, it happens all the time. In your body for instance. Nerve cells 'fire' by building up a ",
"charge difference",
" in the form of calcium or potassium ions, which are then released. The ",
"mitochondria",
" in your cells produce ATP molecules by 'pumping' H",
" ions across a membra... | [
"so does this mean that, theoretically, there is a way to create a positively charged liquid, if you have the right amount of power(via electrical fields or,...) and are able to apply it in a sense that would separate the positive from the negative molecules?"
] |
[
"What is it that makes our brains like sponges when we're children that gradually goes away?"
] | [
false
] | Until we'd rather ask what's wrong with our brains than force it to do the revision that used to be . | [
"When you're young, your brain is still making millions of neural connections and is the most plastic, or changeable. You brain doesn't fully develop until your mid 20s but the most drastic changes occur younger than that, mostly before puberty. If you think about it, your brain has to learn so much--language, fine... | [
"Thank you"
] | [
"Expanding on this. Is there any research or information showing a prolonging of this plasticity? Ie, besides being a healthy person are there ways to prolong the brain's \"spongy state\"? Obviously you never stop learning, but it seems like an attractive idea to learn a language as fast a child."
] |
[
"Is \"burn in time\" for headphones real or a myth?"
] | [
false
] | Burning in is usually referred to the time it takes for headphones to reach optimal quality after being taken out straight out of the box. My question is if burning in is real or a psychological affect. | [
"Piston rings, cylinder walls, valve guides. Engines have tons of metal parts sliding on other metal parts, and in the first few hundred miles they wear into each other at a level that's not economically feasible to do before assembly. That's why you should change your oil after ~1000 miles or less, because there i... | [
"Is there a measurable effect? Yes. Is it a noticeable effect? Probably not. I'm not sure how headphones would compare to regular speakers, but the physical improvement amount is usually around 5-10% for regular speakers. I would imagine that the shorter throw/smaller cones on headphones would have less percentage ... | [
"Although i don't have evidence that burn in time is something measurable, or distinguishable by human ears, i don't think it's an unreasonable hypothesis. ",
"All moving parts change their characteristics after use. Just like how a car manufacturer recommends that you drive a car gently for a few hundred miles.... |
[
"Why is it that with things like video games, the user can't see the source code, but with html pages, the user can?"
] | [
false
] | null | [
"Video games are usually written in a language that makes use of something called a compiler. A compiler takes the source code of the software, analyzes it, and produces machine code that will perform the activities designated by the source code. This output will look nothing like the original source code, but it... | [
"HTML isn't a programming language, it's a \"mark-up\" language. Keep that in mind.",
"Computers don't understand programming languages. A computer is a CPU unit, it only knows voltages at its pins corresponding to 0s and 1s. Your CPU doesn't understand C++ or Java. What it does understand is Assembly or Mach... | [
"JavaScript is a programming language and can be delivered to browsers in a human readable format (though it is often minified) and then interpreted in that format. \"Programming language vs markup language\" is not the distinction here. \"Compiled vs interpreted\" is the correct distinction."
] |
[
"Is 5 hour energy bad for your body?"
] | [
false
] | If it is, what about it makes it bad for your body. | [
"Make sure you don't have ",
"too much",
" of a good thing & you should be alright."
] | [
"Wouldn't this depend on the vitamin and it's solubility?"
] | [
"It would. Any vitamin that you ingest has to be handled by your body. Obviously if these drinks were fortified with fat soluble vitamins then there would be a lot higher chance for toxicity. With water soluble vitamins though they are excreted through the urinary tract, and with some B complexes the feces. Thi... |
[
"Hey scientists...why is it, do you think, that animals like my dog and cat, don't seem to respond at all to music....?"
] | [
false
] | it's so weird, a drop of a spoon and they perk up, but death metal or chopin seems to have NO affect at all....and ideas? | [
"This is not a scientific answer but in the absence of a true response...",
"Animals are very accustomed to ignoring human produced sounds: in particular, anything focussed on the human hearing range around 80Hz-8kHz (this includes most musical instruments regular range except cymbals, triangles and some woodwind... | [
"The same mental pathways that allow us to understand complex language are active when we appreciate music.",
"Dogs and cats lack these pathways. They can understand sounds, even simple commands, but cannot combine sounds together into sentences. The same is true for music, they are unable to combine individual... | [
"They can understand sounds, even simple commands, but cannot combine sounds together into sentences.",
"Not true. Some breeds of dog can understand nouns and verbs, I own such a dog and she very clearly understands sentences. She also seems to like Classical Music and hate the sound an acoustic guitar makes. (Pa... |
[
"Ways to escape heat death of universe?"
] | [
false
] | null | [
"Is the following possible: Using a large initial investment of energy, we accelerate everything we have (our planet(s), flotilla etc) to relavistic speeds relative to CMB and blueshift it appreciably so we have a 'CMB sun'. Ignoring collisions with interstellar and intergalactic media (which would be disastrous at... | [
"Non scientist here, but hopefully by replying naively to you, it will generate better responses! ",
"If we accelerated earth close to c, I don't think this causes the rest of the universe to effectively cease aging, rather, it causes ",
" and the earth to effectively cease aging while the rest of the universe ... | [
"Thanks but I'm pretty sure the rest of the universe will slow down relative to observers on a fast moving frame."
] |
[
"Is there any relationship between an organism's number of chromosomes and it's complexity or features?"
] | [
false
] | I was reading the Wikipedia article on humans and learned that all the other apes have 24 rather than 23 chromosomes. This made me interested in how many chromosomes other species have, and the list I found seems to be all over the place. Daisies have 2, rice has 24, hegehogs have a few hundred, a lot of mammals seem to have around 40, what exactly is going on here? I don't see any kind of pattern aside from the difference between hominids with 24 and 23 chromosomes. Plants, mammals, birds, and insects all seem to have all sorts of chromosome counts, so what's the deal here? Why is there such a massive diversity of chromosomal numbers? Why do things with such different numbers of chromosomes look so similar? Why does it take 24 chromosomes to make rice but only 2 to make daisies? Is rice incredibly compliated? Inefficiently structured? Is a lot of it just redundant junk? I have to say I'm absolutely mystified. This is something I'd never given the slightest thought to in the past but it seems significant. | [
"The relationship is not linear or simple. Complexity is very difficult to define and subjective, so this is a stumbling block in the discussion, but I will take it to mean something subjective, like structural intricacy. First of all, chromosomes are not a good indicator of genome size. In your example, in human e... | [
"There is little to no relationship between genome size and organism complexity. The difference in chromosoome numbers is related to the amount of non-coding DNA present. Some organisms like viruses have none and therefore have very small and uncomplicated genomes while others have a lot of it ( human have ~80% re... | [
"since humans evolved from apes.",
"This is a common misconception. Humans are apes. The lineage that leads to modern chimpanzees have existed for as long as the lineage that leads to modern human. The only reason why humans have one fewer chromosome pair is due to a chromosome fusion event that occurred on the h... |
[
"When pouring a liquid from a cup, why will it sometimes run along the bottom of the cup and then drip instead of coming out the top as expected?"
] | [
false
] | null | [
"Just speculating because nobody is here but I feel it is due to ",
"cohesion",
" of the liquid and ",
"adhesion",
". ",
"For example, water likes to stick to water and charged surfaces, so say that the cup is slightly charged for whatever reason, the water will prefer to go to it rather than air, even th... | [
"There was an article on this in New Scientist magazine some years back but I cannot remember which one, and cannot access their archives from here. However, anyone who has a subscription should be able to search their back issues via the WWW, for an article about a scientific paper on pouring tea from a teapot by ... | [
"While the coanda effect probably contributes, cohesion/adhesion makes a big difference. I discovered while taking organic chemistry that different liquids have ",
" different pouring characteristics. For instance, it's basically impossible to transfer isoamyl acetate to a different container without making a m... |
[
"What's the best way to treat a scrape, cut and minor lacerations?"
] | [
false
] | null | [
"Clean any debris from the wound, disinfect, dry the area and then bandage with a sterile dressing.\n",
"http://www.sja.org.uk/sja/first-aid-advice/wounds-and-bleeding/bleeding.aspx"
] | [
"Moist wound healing",
". ",
"See also",
"."
] | [
"Tea Tree Oil is amazing for minor cuts etc.\n",
"http://en.m.wikipedia.org/wiki/Tea_tree_oil"
] |
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