title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"I have read online that some fabrics have antimicrobial properties. Is this true? How does this work?"
] | [
false
] | [deleted] | [
"Antibacterial metal-infused clothing contains copper, which as a surface material has antimicrobial properties due to several chemical interactions it can have with bacterial cells.",
"Effects described here: ",
"https://cuverro.com/resources/faqs/how-does-copper-kill-bacteria",
"Copper-infused clothing has ... | [
"I forgot to mention hemp here but in this article it appears that hemp fibres do have antibacterial activity possibly due to cannabinoids or other bioactive compounds:",
"https://bioresources.cnr.ncsu.edu/resources/antibacterial-properties-of-hemp-and-other-natural-fibre-plants-a-review/"
] | [
"Additionally, many silver infused hospital scrubs are advertised as bacteria resistant while various studies have found no beneficial effects to their use. One therefore has to be careful that using these doesn't produce a false sentiment of security. ",
"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3382727/",
... |
[
"Is it safe to boil water in a plastic container?"
] | [
false
] | I've recently learned that boiling water in a plastic container such as a water bottle is survival tactic. I can understand this in unusual circumstances. However, I'm wondering if this would release other toxic bits into the water by doing this. | [
"A lot of reusable water bottles now advertise BPA free so many are safe from BPA probably even when boiling. However, that's not to say that there aren't more potentially harmful substances in plastic containers that might leach out. BPA is used in other containers also like for lining metal cans for food and be... | [
"A lot of reusable water bottles now advertise BPA free so many are safe from BPA probably even when boiling. However, that's not to say that there aren't more potentially harmful substances in plastic containers that might leach out. BPA is used in other containers also like for lining metal cans for food and be... | [
"I'm almost positive plastic will boil water. The parts of the plastic containing water cannot melt. ",
"this",
" vid.",
"Points of interest will be at 3:20, 6:40, and 11:50 along with his video comments."
] |
[
"What exactly is meant when by electrons being negatively charged, protons positively charged, and neutrons having no charge?"
] | [
false
] | I understand that protons are positively charged, electrons are negatively charged, and neutrons have no charge, but why? What exactly is "negative" about an electron and "positive" about a proton? I understand that positive repels positive and positive attracts negative, but beyond these properties how does a positively charged particle behave differently from a negatively charged particle? I read that the charge of a particle is determined by its response to the electromagnetic field, but how? | [
"guessed, and got the answer wrong",
"Not true, that's a popular myth. It's based on the wrong idea that positive charges are not real, and that electric currents are flows of electrons.",
"Electric current in human bodies is a flow of positive sodium and an opposite flow of negative chloride ions. When you g... | [
"We can do a little bit more than just say \"charge exists,\" and leave it at that. There is a principle of the universe called U(1) gauge invariance. U(1) gauge invariance explains a variety of things -- why there is a photon, why the photon is massless, and why there are electromagnetic fields and waves. It als... | [
"We can do a little bit more than just say \"charge exists,\" and leave it at that. There is a principle of the universe called U(1) gauge invariance. U(1) gauge invariance explains a variety of things -- why there is a photon, why the photon is massless, and why there are electromagnetic fields and waves. It als... |
[
"What happens if you repeatedly melt glass?"
] | [
false
] | If you have glass and you melt it, then allow it to cool and harden, then melt it again and repeat a few times, will the glass become brittle? What change will happen to the glass? | [
"Glass is already tremendously brittle.",
"But to respond to the substance of your question: glass doesn't have a memory. It doesn't remember that it's been melted 50 times before in the last 24 hours instead of 1 time. So the parameters that affect the properties of glass are simply those of the most recent melt... | [
"It exists as its own creature now. Let it float freely on the currents of the internet, educating mildly curious people around the world :)"
] | [
"Glass is complicated. Tempering is usually done in a separate step after it has been shaped - it is reheated until gooey and then cooled. Annealed glass can start liquid and is brought down gently, but not so gently that it has time to crystallize and devitrify."
] |
[
"What causes very salty water to be visibly different from pure water when the two are initially combined?"
] | [
false
] | I work as an RA in a neuroscience lab and regularly have to dilute a 10x saline solution. Whenever the concentrated salt water is added to pure water there are visible "waves" much like you see on the highway on a hot day. After it is fully mixed these waves are no longer apparent. Is this due to different densities between the solutions or is the charge from ions causing refraction in some regions and not others? Something else entirely? | [
"It is due to the different indices of refraction. You can see ",
"this table here",
"What you see when there's a mixture of two indices is called a schlieren."
] | [
"I understood that different refraction properties cause these visual differences, but was curious as to why they are different (density, ionic charge). ",
"Schlieren is an awesome new word though, thanks! "
] | [
"The refraction properties go back to the polarisabilites of the molecules/atoms in the solution. Because you have sodium an chloride in one part and none of those in the other the refractive indices of the solutions differ. At the surfaces of these different solutions the light will change direction just like it w... |
[
"Are quantum leaps in FLOPS feasible with current technology?"
] | [
false
] | [deleted] | [
"You have built a computer that utilises each of the 10",
" atoms in the observable universe as a core. Each of these cores is capable of running at the fantastic rate of a million-billion-",
"googol",
" ( 10",
" ) expressions per second. Your computer has been running for 13.7 billion years (4.3x10",
" s... | [
"That is the most upsetting, yet strangely gratifying thing I've heard today. On one hand, it's a sad realization of just how large the number is. On the other hand, I suppose it means that my analytical research is actually useful and won't just be obsolete one day (Like many-a-paper of last century). Thanks for t... | [
"For a while, computing trends followed an empirical observation known as ",
"Moore's law.",
" (It's not a causative law, it's just an observation). It states that computing powers have been growing exponentially for some time. That's pretty nifty, but if you talk to anyone who knows their stuff about this, the... |
[
"Is the strength of a magnetic material based solely on the amount of pure magnetic material present? And are iron,nickel and cobalt equal in their magnetic strength? Why/why not?"
] | [
false
] | null | [
"You also have the interactions of mixes of materials. For instance the alloy ",
"Alnico",
" is a mix of aluminum, nickel, iron, copper, and cobalt. But the mix makes a much stronger magnet than any of the pure ingredients. With aluminum and copper considered completely non-magnetic.",
"The composition of aln... | [
"You also have the interactions of mixes of materials. For instance the alloy ",
"Alnico",
" is a mix of aluminum, nickel, iron, copper, and cobalt. But the mix makes a much stronger magnet than any of the pure ingredients. With aluminum and copper considered completely non-magnetic.",
"The composition of aln... | [
"Great answer, thank you so much! I had come across several of these points searching the internet but none that answered my question so completely. Also, given you are looking at a diagram of magnetic field lines around a magnetic object, is the magnetic force stronger along these lines than in between them? Or is... |
[
"How does the brain decide when to release dopamine?"
] | [
false
] | As we know, dopamine is responsible for making us feel good after we do some action (often stupid acts). How does brain knows which acts deserves dopamine release and which don't ? | [
"As always with most neuroscience-related questions, we don't have a well-worked out theory for how value is represented and learned in the brain. That said, we do know some pieces of the puzzle. First of all, nervous system function is very tightly related to patterns of neural firing in different systems. These p... | [
"Dopamine is responsible for so many things! There are actually 4 major dopaminergic pathways which have varied functions like motor control and assisting in endocrine function.",
"The one you are referring to though is the mesolimbic dopamine pathway. This is the widely discussed \"reward pathway\". Basically do... | [
"Yeah, you described the mesolimbic pathway pretty well. However, dopamine has more recently been considered for learning behaviors, helping our attentiveness to pair operant behaviors with associated rewards, not necessarily acting as a pleasure chemical itself. They think glutamate is that pleasure chemical. (Not... |
[
"Does our brain having to flip everything we see as a result of our upside-down retinas impact/decrease reaction time?"
] | [
false
] | I recently learned that our retinas are upside down, thus our brain has to flip everything we see in order to well... Not see everything upside down, so I've been wondering if the extra task of fliping the image cause a measurable decrease in average reaction time. | [
"I was skeptical simply because it seems like it would a difficult and unpleasant experiment to do.",
"You underestimate how inquisitive and dedicated scientists can be. Some of them have worn those glasses for days at a time, and the brain does adapt.",
"https://en.wikipedia.org/wiki/George_M._Stratton#Wundt's... | [
"Your brain does not have to flip anything. The image on your retina is only inverted relative to another upright person looking at your eyeballs. Your brain does not have a separate pair of eyes. Information from the bottom part of the retina just corresponds to the upper part of the world.",
"By analogy: if you... | [
"I dont know if this is true, but I read that if you give a person glasses that flips things upside down the brain will after a period of time flip it. I was skeptical simply because it seems like it would a difficult and unpleasant experiment to do."
] |
[
"Any techy's about or Internet service provider experts?"
] | [
false
] | null | [
"Hi ",
"/u/deano2440",
" ,",
"Your question is quite vague. Mobile and \"landline\" networks differ because they have different objectives. Thus, they use different technologies - there is no one-size-fits-all solution.",
"If you have more specific questions, feel free to resubmit.",
"Cheers."
] | [
"Thank you, well, in my local area, the internet is soooooo bad, legit.\nDuring gaming, I am often DC'd due to the connection of my internet. However, i do not disconnect or have any issues when i hotspot the PC to my phone which runs 4G! \nI just thought if I am able to get better/stronger connection from a hotspo... | [
"edit: in my area (maybe different in other areas)"
] |
[
"If you have already done PCR what are the reasons you would want to transform bacteria with your PCR product?"
] | [
false
] | [deleted] | [
"E.coli replicates the plasmids with extremely high fidelity, at least 100 times better than the best available polymerases . Also an overnight culture can easily give you milligrams of plasmid DNA. plasmids can also be used to transform other organisms like bacteria, yeast, even human cells. "
] | [
"plasmids can also be used to transform other organisms like bacteria, yeast, even human cells. ",
"This is usually the reason. If all you care about is the sequence you can sequence the PCR product directly (eg. if you want to be really sure your primers are amplifying exactly what you think they are). You clo... | [
"This is basic cloning. In this particular case yes, they just want you to be familiar with the technique. In a molecular biology lab there are a ton of reasons why one would want to clone a piece of DNA. This is the basic methodology used for making recombinant dna products and can be the first step for things lik... |
[
"Does a series always either converge or diverge, or is there a middle ground?"
] | [
false
] | And what would that mean? | [
"It does not converge to 1/2. It is divergent, hence it has no sum.",
"However, the \"Cesaro-sum\" of this series is 1/2. But the Cesaro-sum is not the same as the sum. "
] | [
"A divergent series is one that does not converge, so there is technically no middle ground. Divergence doesn't necessarily mean it goes to infinity or -infinity, though, if that's what you're asking - for example, (-1)",
" is a divergent series:",
"-1, 1, -1, 1, -1, 1, -1, 1, ..."
] | [
"Some types of divergences can be \"tamed\" and given reasonable answers. There are various summation methods which agree with normal limits when they exist, but can also assign \"sums\" to series that don't have a limit. A basic one is Cesaro summation: replace the series at each step with the average of all its v... |
[
"Why are thermoplastic polymers more easily recycled than thermosetting polymers?"
] | [
false
] | I've read that thermoplastics can be recycled but their properties degrade in the process (why?) Thermosettings are hard to recycle but I don't get exactly why? | [
"Thermosetting plastics solidify through a chemical reaction which forms links between short polmyer chains (cross-linking). These cross links are permanent bonds which lock the structure in place, making the shape rigid. ",
"Thermoplastics on the other hand are just frozen liquids. They're not too dissimilar to ... | [
"yep, comes down to what happens when you heat it. Thermoplastics melt and you get a liquid, so you can put it in a new mold, mix it with stuff etc. Thermosets change chemically when they set, so when you heat them up they just degrade and burn but won't melt. Much harder to make something new when it won't melt.... | [
"Thanks a lot! "
] |
[
"Why do bees die after they sting? Biology"
] | [
false
] | null | [
"For a bit of clarification, bees only die when they sting certain animals - notably mammals - most reptiles, birds and other insects they can sting repeatedly."
] | [
"Second post as this is less factual and more speculative and thus might get downvotes...",
"When bees sting and the stinger remains, so does the venom sack and associated muscles. This will continue to pump venom, even after the bee is swatted away, and be harder for an animal to remove (while killing the bee w... | [
"Not a scientist, but, here is how I understand it:",
"The bee's stinger is an excellent tool in insect-on-insect combat. It's only when they use their stinger on larger animals such as humans that they run into the problem of dying after a sting.",
"I'm not totally sure on why this happens, so, I'll let someo... |
[
"If water is such a good electrical conductor, why don't millions of fish die every time lighting strikes an ocean?"
] | [
false
] | Unless they do of course, but we never hear about it or have mass schools of dead fish wash up on our shores after every storm | [
"I am by no means an expert but I think that the electrical resistance of the fishes body is the main reason this doesn't happen. Compared to the resistance of the water the fish is just a higher resistance parallel resistor. ",
"I am under the impression that the charge is built up at the surface, meaning the ... | [
"Water itself is actually ",
" a good conductor. It is all the impurities within the water, such as the minerals, that make it appear to be a good conductor.",
"As to lightning travelling, it is the same reason an electric eels shock only goes so far... which I am wracking my brain searching for the memory. I b... | [
"I expect fish do die, yes.",
"Sea water is a good conductor, so I assume the current spreads more or less spherically. The damage done to tissues, I'm guessing, is inversely proportional to the volume of that sphere. (Though it could be the surface area.)",
"An electric eel, assuming a half-second discharge (... |
[
"Why exactly is a 100% efficient process impossible?"
] | [
false
] | [deleted] | [
"Friction is a good culprit in mechanical systems, but equivalent types of loss occur in other systems (e.g. viscosity leads to drag in fluids; randomization of electron paths leads to ohmic resistance in electrical systems).",
"I think the concept you're reaching for is this: it is never, in practice, possible ... | [
"What does efficiency mean to you? Yes you can keep a current going forever. But if I throw a ball in space it will also keep going forever. There isn't any energy gained out of the system."
] | [
"The answer is, once again and always, entropy. If you do the math, for an ideal system with net entropy dS = 0, the efficiency is n=1-Tc/Th, where Tc is the temperature of the cold side, and Th the temperature of the hot side."
] |
[
"What are actual humanity endangering threats of Global Warming/Climate Change?"
] | [
false
] | Like - rising sea-levels. That's gradual isn't it? People can either see the sea getting closer every year and move, or if they want to stay where they are so bad, they can build sea-walls or whatever. Rivers and coast-lines have moved throughout history and people have had to move. Or the rising temperature and crops - if it gets hotter up in northern latitudes can't you just grow the varieties that were being grown further south up north, if the heat is bad for northerly varieties? Or desertification, the Sahara didn't used to be a desert, now it is. If some places become deserts, then people will have to move, or try to prevent desertification. So, that's the gist of my question - I always see people talk about Global Warming as a threat to humanity, like our survival as a species, and I don't see it. What am I missing? Sure, it'd suck to be living a place that goes underwater/becomes a desert, and you'll have refugee crises/famine/disease, but would the scale really be any larger than modern refugee crises/famines/disease outbreaks given that the timescale is in decades? Moreover, those seem like 'third world problems' - what threat does GW present to a first world country like the US that presumably has the ability to prevent things like desertification, build sea-walls, import heat-resistant varieties of crops/genetically engineer new ones? Sorry if this is a little rant-y, I want to describe my understanding of the issues, so that an expert (or someone more well-informed) can address them explicitly. | [
"The agriculture issue is not trivial.",
"Assuming the climate belts migrate to more polar latitudes you have to appreciate that firstly, that means the agricultural land has to move a long way from teh traditional population centres. That means very significant population displacement, even if you ignore the sea... | [
"We will almost certainly survive as a species, yes. However it'll have ",
" economic effects.",
"Sure, people can move, but they shouldn't have to. A raise in sea levels is going to destroy a lot of unique ecologies. Yes, some of those effects of those ecologies might be repeated, but not necessarily.",
"... | [
"Like - rising sea-levels. That's gradual isn't it? ",
"It is gradual, but as we just saw with Sandy, even gradually increasing seas can cause sudden and disastrous damage to inland areas that seem safe on a day-to-day basis if they are hit with a storm surge. Sandy was not a hurricane when she made landfall, but... |
[
"How do carcinogens actually cause cancer?"
] | [
false
] | Specificity would be awesome. | [
"SO many ways. First, it's worth understanding the surprising level of regulation of when cells can grow and divide. Some proteins favor growth and division, some oppose it. The genes that code for these proteins can get altered by anything that can bind to DNA/react with it/break it. Cells are pretty impressive at... | [
"This was a great answer; exactly what I was looking for. Thank you "
] | [
"As you probably know, cancer is caused by pathogenic mutations in your body cells DNA that result in abnormal proliferation. Carcinogens can be genotoxic or nongenotoxic. For example, radiation is genotoxic as it directly disrupts DNA. Smoke contains pyrolytic products that bind do DNA and disrut it this way. Nong... |
[
"Is the universe on a plane?"
] | [
false
] | [deleted] | [
"Is the universe on a plane like a disk or only the galaxies that spiral inward?",
"Only the galaxies. There is no reason to believe the universe as whole acts as a rotating sphere - aka disk.",
"Why does it look like a spiral galaxy seems to rotate on a plane? ",
"Conservation of angular momentum."
] | [
"The problem with the determining the shape of the universe is that there is and there probably will never be any way to see it. We are trapped inside an ever expanding sphere of space-time called the observable universe. The only way to know otherwise is to see an impact of the side of the universe on something (m... | [
"No. The universe is shaped like a giant, expanding bubble. Many galaxies really are often shaped like rotating disks -- thicker than a plane but oriented along a plane."
] |
[
"Does a steel bar resist bending until a certain amount of force is applied, or does all force bend it, however slightly?"
] | [
false
] | [deleted] | [
"Yes. All solids undergo small elastic deformations due to even small applied forces. The ratio of applied force to displacement (normalized by the area and length) is called the elastic modulus, or simply modulus. The elastic modulus for steel is around 200 GPa. Interestingly, this extends to even tiny displac... | [
"So to clarify, your saying that steel will bend under any force, but it will move itself back into place unless a sufficient amount of force is applied and it is bent to a certain extent, yes?"
] | [
"1 GPa is a typical value for Ultra-high strength steels UHSS which are actually some of the most widely used grades, eg car paneling. But \"steel\" comprises a huge array of alloy families, with yield strengths ranging from < 200 MPa to over 1500 MPa. You are probably used to high- strength low alloy steels (HSL... |
[
"What stops inter-species crossbreeding? If a horse and a donkey can make a mule, why can't we crossbreed say a dog and a cat?"
] | [
false
] | Also, what other inter-species crossbreeds are there? | [
"Horse and a donkey is a great example. As are dogs.",
"Speciation isn't a switch. You don't suddenly get a new species in one generation, rather it is a very long gradation of between divergent phenotypes.",
"The idea of a species is largely a human construct that doesn't capture all the detail of nature.",
... | [
"It's nice to see that searine's here already and has done a good job explaining the basic ideas. I'd like to take a moment to talk through a bit more explicitly some of the genetic incompatibilities he mentions.",
"Consider two arbitrary genetic loci. The \"A locus\" and the \"B locus\". Imagine that your entire... | [
"Reproductive isolation are mechanisms that prevent interbreeding to occur in nature. You can read all about it here! ",
"http://en.wikipedia.org/wiki/Reproductive_isolation"
] |
[
"What would a spaceship experience if it flew through a nebula?"
] | [
false
] | I was just checking out some photos of the pillars of creation and was wondering what would it be like. Are they all made of just gasses, or is it more like a debris filled. | [
"Wildly disappointing, unfortunately. All that gas is spread out over a truly incomprehensible area of space, and up close it would likely be too dispersed to see much. It’s really only from such massive distances away that we can really appreciate their splendor"
] | [
"Basically gases, that's right. There are different kinds of nebulae, with some being pulled together from the interstellar medium and then birthing stars, to others being created as dying stars shed or explode outer layers. But really in all of those cases, you're talking about gases of some kind.",
"The ",
"C... | [
"Nebulae are clouds of extremely sparse gas. The maximum density might be a million molecules per cubic centimeter, which is less than one-trillionth as dense as air. Most parts of the clouds will be even less dense than that. A spacecraft would need sensitive detectors to even notice that it had passed into the ne... |
[
"From what I understand, we have a lot of trouble surgically reconnecting nerves. That being the case, how do transplants work? If we can't really reconnect nerves, how does the transplanted tissue function?"
] | [
false
] | null | [
"Nerves like those directing muscle movement - aka motor nerves, need to be in the right \" orientation\" because they map all the way into our spine and brain in a set pattern. A specific patch of your brain controls your pinky versus ring finger, but both are carried by the same nerve sheath in your wrist. Simila... | [
"It used to be stated as fact that nerves don't grow. Now we know that is not true. Nerve reconnection requires skilled micro-surgeons but it is being done, fairly routinely now. ",
"http://www.hopkinsmedicine.org/health/articles-and-answers/ask-the-expert/behind-hand-and-arm-transplants-1",
" ",
"For a nerv... | [
"Had a similar surgery back in 95. Same result. 20 years later a small portion of my ankle is still numb. Everything else came back, but right along the scar is still numb. It took 10 years, but the foot finally got feeling back. I also had an intense \"light socket\" feeling on the scar when it was pressed. Couldn... |
[
"Why is it that certain age groups are subject to hearing certain frequencies? Such as the mosquito tone."
] | [
false
] | I'm sure most people have heard of the mosquito tone or the tone that only young people can hear, but why is it that only younger people can hear this tone? Same question applies to other frequencies, why does it just cut off at a certain age? | [
"It doesn't \"just cut off\", but it does decrease with age. The portions of the human cochlea used to perceive high frequencies are the most metabolically active portions of the cochlea, and thus the most susceptible to die from lack of nutrients/oxygen from overstimulation. Pretty much everyone loses some of them... | [
"Could you elaborate on the reason that they require more energy?",
"I'm not familiar with the studies that show basal hair cells are more metabolically active. Maybe they (outer hair cells) are because they have to deal with higher frequencies at the base. ",
"Is it because high frequencies are detected near... | [
"Could you elaborate on the reason that they require more energy? Is it because high frequencies are detected near the cochlea's entrance, so all frequencies must go through that region?"
] |
[
"Why is it that humans and many animals make loud noises when in pain?"
] | [
false
] | null | [
"Instinctual trait to tell others that there is something bad in the vicinity, and that they need help. "
] | [
"Also important for animals that play. Dogs and wolves, for instance, can bite when they play. A yelp when in pain will tell their partner to stop. This is one way pups learn how to be gentle and how hard is too hard to bite when playing."
] | [
"You know what the OP meant. This nitpicking adds nothing."
] |
[
"Have there been any models that predict what conditions are necessary for Great Powers to engage in war in the modern era?"
] | [
false
] | null | [
"Absolutely--there is a robust literature surrounding the prediction of conflict, although it does not tend to revolve around \"great power\" conflict specifically. You can grab your data from recent history and then plug whatever predictor you want into a logistic regression. Some factors important in the predic... | [
"This fascinating paper you linked to predicts a global decline in conflict. Is the model they are using strong enough to justify a sense of relief?"
] | [
"These are some of the strongest indicators of impending conflict, and the paper made conclusions based off of those variables. It's only logical that the effects would transfer into real-world situations."
] |
[
"Is there any dark matter in my room right now?"
] | [
false
] | [deleted] | [
" Maybe. It depends what dark matter is.",
" ",
" is a bit of a catch all term. It's just meant to describe the bulk of the apparent gravitating mass in the universe which is not luminous. We don't know what it is yet. The evidence is really really good that it exists, we're just not sure what it is. ",
"Gene... | [
"Good question, and the answer is 'Yes.' The two main detectors at the Large Hadron Collider, for example (ATLAS and CMS) both reconstruct \"Missing Energy\" as one of the variables they look for in each collision."
] | [
"Good question, and the answer is 'Yes.' The two main detectors at the Large Hadron Collider, for example (ATLAS and CMS) both reconstruct \"Missing Energy\" as one of the variables they look for in each collision."
] |
[
"Do currents stop at extreme depths, or are the oceans always moving, everywhere?"
] | [
false
] | [deleted] | [
"Yes there are currents at all depths, but the magnitude of the currents is generally smaller at depth. . In the early days of oceanography it was thought the deep ocean was nearly motionless but once they were able to actually make measurements they discovered sizable varying currents. This article on the ",
"... | [
"That's a good point about water mass properties being characterized by the water properties in their formation regions. It's one of the key diagnostic properties of ocean structure and was used to infer ocean circulation long before we had direct measurements. I would consider movement of water masses part of ocea... | [
"I was going to mention water masses and their movement in thermohaline circulation, but I don't believe they are considered currents, is that correct?",
"That said, there is slow movement of water in deeper parts of the ocean driven by differences in density due to salinity and temperature. I think the most inte... |
[
"Is it possible for an asteroid (or spaceship) to actually \"skip\" off the atmosphere?"
] | [
false
] | My understanding is that when people talk about objects "skipping" off the earth's atmosphere, it generally doesn't mean "skipping" in the sense of a stone skipping on a pond. Instead (my understanding is that) it refers to the fact that an object approaching the earth on a non-orbital trajectory that enters the Earth's atmosphere at a shallow enough angle will not bleed off enough speed through drag (and other atmospheric forces) to enter into orbit of the earth. The object is slowed, but ultimately exits the atmosphere on an escape trajectory. This would, for example, be the kind of "skipping" they were concerned about with respect to the Apollo 13 mission. That said, is it possible for an object to actually "skip" an object off the atmosphere in a manner similar to skipping off a pond? I don't see any reason it shouldn't be possible. Stones skip off water due to creation of lift and an object entering the atmosphere certainly can also create lift. I don't see any reason that lift couldn't be enough to lift the object back out of the atmosphere similar to a skipping stone. As a follow up, I suppose that generating lift wouldn't increase orbital velocity, so the stone like type of "skipping" couldn't propel an object into an escape trajectory that didn't enter the atmosphere already on an escape trajectory. Since intuition and orbital mechanics generally don't play well together, is that intuition correct? | [
"In general, no. Objects can certainly have an orbital trajectory that grazes the Earth's atmosphere at a small enough depth that it doesn't lose sufficient energy to deorbit; this actually happened with an asteroid ",
"in 1972",
", but this is not the \"skipping\" process you are describing. ",
"A stone skip... | [
"This could perhaps work.",
"It does work. That's how you run a skip-glide reentry - you dig into the upper atmosphere in such a way that you slow down in horizontal velocity and meanwhile actually start flying back up into space again due to lift, then \"re-reenter\" and land somewhere further downrange. I suspe... | [
"Kinda like Neil's X-15 flight.",
"https://www.airspacemag.com/daily-planet/neil-armstrongs-x-15-flight-over-pasadena-59458462/",
""
] |
[
"Can I \"give\" antibodies to people as I give them diseases?"
] | [
false
] | For example, if I have Influenza and have already developed antibodies for it, can I (with a sneeze or blood transfusion) "pass" those antibodies to someone else (Assuming we both have the same blood type)? | [
"That's an excellent question. You are equally likely to pass a single antibody or a single virion to your friend. The single copy of the influenza virus will make millions of copies of itself once it gets into cells, the antibody will not. That means that the virus will take off and colonize the host, the antibody... | [
"Yes, patients are given antibodies routinely in the clinic. There are ",
"many monoclonal antibodies approved by the FDA",
"; however, these are most commonly given as cancer therapeutics or for autoimmune diseases. ",
"For the situation you are describing (i.e. giving antibodies for influenza), this is not ... | [
"wrt to the second part of this blokes answer, this is actual treatment for certain diseases and goes by the name passive immunity. also, blood type would be completely irrelevant as it is MAINLY for red blood cells only."
] |
[
"Why is there sometimes a halo of light around a plane's shadow on the ground (at least when seen from the plane)?"
] | [
false
] | I took on a recent flight, during landing (as you can see by the size of the trees, we're not very high up). It looks as if the ground around the shadow is actually being more brightly illuminated than the surrounding area. That seems super weird to me. | [
"That's called a ",
". Sunlight gets reflected/refracted twice inside the droplets that are in the air. In your picture it isn't very clear, you have a thin cloud veil. Google \"glory, optical phenomenon\". It's something similar to what happens in a rainbow. There are two theories: here light also travels aroun... | [
"Plenty of things are called sun dogs, that aren't sun dogs. :-)",
"\nSun dogs are ",
"patches of color to the left or right of the Sun",
" (never anywhere else -- if so, they are likely some other form of ",
"ice halo",
")."
] | [
"Cool, thanks!"
] |
[
"Does visible light have properties other than being visible to humans?"
] | [
false
] | It seems like most of the other types of EM radiation have some property that's much less arbitrary than "we can see it," i.e. X-rays are similar in magnitude to atomic crystalline structures so we can do crystallography, microwaves are capable of fast energy transfer to water molecules, etc. If we couldn't see 350-750nm, would it be interesting at all? | [
"Oh, definitely! For starters, these are generally the colors of light that make it through the atmosphere from the Sun in highest abundance. We're using the most common photons to see. Beyond that, these energies are very important to biological life, due to the chemistry involved. To explain, I need to clarify so... | [
"Wait! Does it mean that visible light and green chloroplasts are another example of processes happening in a Goldilocks zone? Would we expect alien animals to see in similar wavelengths and alien plants to be green?"
] | [
"Visible wavelength lasers are crucial for biological science and microscopy. We can attach fluorescent markers to cells that will emit a different visible light if lit with the right wavelength. Different cells often bond with different markers, so by looking at what's fluoresced when you light up a sample of cell... |
[
"Why do men go bald while females don't?"
] | [
false
] | I know not all males go bald, but I know that many do. I am yet to encounter a female going bald though. Is there a specific reason for this? | [
"Yeah, but hair loss isn't the exact same thing as baldness. I understand that women have thinning hair, receding hair lines, and bald spots, but how come we never see a woman with a shiny bald head and the cul-de-sac of hair like we do men? Are they all just wearing wigs?"
] | [
"Yeah, but hair loss isn't the exact same thing as baldness. I understand that women have thinning hair, receding hair lines, and bald spots, but how come we never see a woman with a shiny bald head and the cul-de-sac of hair like we do men? Are they all just wearing wigs?"
] | [
"This is mostly not true:",
"Balding is multifactorial, with several lines of evidence suggesting that it most likely functions by a diathesis–stress model. Since androgens and androgen receptors (AR) are the initiating cause of androgenic alopecia, their genetic corollaries are a subject of much research. Some i... |
[
"How can black holes conserve angular momentum while being infinitely small? Do they spin infinitely fast?"
] | [
false
] | [deleted] | [
"While, as per the other comment, it's true we don't have a complete answer to this, the speed of light does not impose a limitation into how much angular momentum you can pack into an object of given size. Momentum does not increase linearly with velocity in relativity, and you could, in principle, continue packin... | [
"So basically angular momentum is analogous to kinetic energy (and linear momentum?) in that it is unbounded as you asymptomaticly approach the speed of light?",
"That explains where my confusion came from about singularity size.",
"Points about quantum gravity below a certain size have been made as well, and i... | [
"I found the relativistic definition of momentum ",
"here",
", which is just the Newtonian definition times the Lorentz factor. As you can see, as v approaches c, the denominator will approach zero, meaning the term as a whole approaches infinity."
] |
[
"How do the blind perceive space for motor control?"
] | [
false
] | I've been learning lately and reading some papers about how the superior colliculus receives input from the eyes and that's sent to pre-motor etc. But how is auditory or somatosensory integrated into this system? In a blind individual would the superior colliculus be taken over by auditory input? Or does auditory normally have input from another part of the brain that would just grow much larger? | [
"Most people think that there are five senses: Touch, taste, smell, hearing, and seeing. (haptics, olfactory, etc...) But there are actually a few more. There is thermoception, ability to tell temperature, which is not based on touch. Nociception, the sense of pain. Equilibrioception, ones sense of balance. And fin... | [
"so the question boils down to \"how can we calibrate proprioception without sight?\" "
] | [
"Probably the same way we can calibrate (roughly) the temperature that will burn us, without touching it. Humans are probably born with a certain level of innate coordination, like how a fawn can run only a few minutes after being born."
] |
[
"Does it take more or energy to launch an object into orbit towards the East or West?"
] | [
false
] | Specifically with reference to the effect of the rotation of the earth? | [
"The site of the ESA's ",
"Guiana Space Centre",
" was selected because of its proximity to the equator. That way, the space craft gets some free extra kinetic energy from the earths rotation.",
"See also ",
"here",
":",
"A final point to make is that this speed bonus also explains why rockets are launc... | [
"Just to add to this, there are very few satellites that have been launched westwards. The only country that does is Israel, to avoid flying over the neighbours."
] | [
"That's a hilariously sad fact."
] |
[
"With how many drops of water could you mix a single drop of blood and still be able to determine the DNA of the blood sample?"
] | [
false
] | [deleted] | [
"In theory an infinite amount, assuming there is no contamination in the water. In practice you will be limited by either the capacity of your centrifuge (>4 liters is tough to spin on most centrifuges) or the DNA isolation column (which could probably be made larger, but are designed generally for <10 mL)."
] | [
"DNA has a relative density of 1.7. If you spin a homogenized cell extract for 10 minutes at 1,000 g you will get a nice pellet of DNA. You can then pour off the supernatant and resuspend in whatever volume you want. This processed has been done millions of times for >70 years.",
"While DNA is a discrete molec... | [
"There's other ways to enrich which would bypass the centrifuge/column limit, e.g. evaporation or WBC pull-down using antibodies."
] |
[
"I'm trying to understand the whole current is equal to the voltage divided by the resistance and I think I'm misunderstanding it."
] | [
false
] | What I understand is this: voltage would be the same thing as power if it weren't for resistance. So If I had 3 volts divided by 1 ohm it would still be three volts. So does that mean a volt is measured assuming there is one ohm of resistance? And if that's the case then what you're really doing to find current is saying okay turns out there's more resistance than we assumed(1 ohm) so the actual voltage is a little lower than we initially thought which in turn reduces the power output. Is that right? Although if that was the case why couldn't they just do this: voltage/current * voltage | [
"Ok, please don't take this the wrong way, but you have a base misunderstanding so let's break it down together;",
"---What I understand is this: voltage would be the same thing as power if it weren't for resistance. --- \nBut, it is not... You're thinking about it backwards. Power would be the same as voltage if... | [
"I was reading the last part where you put second/coulomb and I'm wondering what's the difference between coulomb per second and second per coulomb. They sound the same but mathematically they would be pretty different right?"
] | [
"I was reading the last part where you put second/coulomb and I'm wondering what's the difference between coulomb per second and second per coulomb. They sound the same but mathematically they would be pretty different right?"
] |
[
"Would it be possible to create an upside down cone shaped ceramic ice cube tray that wouldn't explode?"
] | [
false
] | null | [
"They probably do to some degree, but from everything I've seen on freezing dynamics they are designed to freeze from the top downward and push the cube slowly upward as it goes. This is also the explanation most commonly given for the times when you get a whole tray that just shatters instead of coming out as nic... | [
"This is pretty much how most ice cube trays already work, the sides slope so that the bottom is smaller than the top and the expanding ice pushes the cube upward to relieve the stress from freezing expansion. If you wanted to make a ceramic ice cube tray you certainly could, though depending on what kind of ceram... | [
"Interesting, I was under the impression that the plastic trays were flexing to some degree under the pressure."
] |
[
"Do forests have natural life cycles, or will they go on indefinitely without interference?"
] | [
false
] | null | [
"Trees, yes. Forrests, maybe not how you are thinking. Theyare referred to as \"stochastic\". Trees fall, other species move in for a bit, old tree type returns. Fire wipes out a patch, grasses, followed by bushes reclaim, but the Trees come back. Over a long enough time scale, because of Tectonic motion, the Trees... | [
"They wax and wain. They move, they change.",
"Even where I grew up, the woods are always changing. Some of our woods are old growth that have been changing over as the old White Pines die from blister rust. That opens up the canopy and regen comes up in it's place. Usually Aspen and Alder. In the meadow, wh... | [
"Ooh, so there's a lot to discuss on this topic! So back in the mid twentieth century, when the science of ecology was just getting started, there was a popular theory that forests were essentially indefinite without disturbance. After a disturbance like a tornado or forest fire, ecological succession would occur a... |
[
"Carbon is such a critical component of complex molecules because it can form 4 covalent bonds. Can silicon be used in a similar way?"
] | [
false
] | null | [
"Yes, in some sense. The chemistry is similar, but the products will likely be very different. Take carbon dioxide, a very simple, rather plentiful, and essential gas for life on Earth. The silicon counterpart is silicon dioxide, commonly seen as sand or quartz. So in theory, life could develop using silicon, thoug... | [
"The only option that yields a gas would be fluorine, but fluorine atoms can only bond to one atom while oxygen can bond to two, so silicon fluorine chemistry is a lot less complex than carbon oxygen chemistry"
] | [
"Not really.",
"The issue goes beyond just the number of bonds that carbon (or silicon) can form. The types of bonds and their stability are important. Carbon can form single and multiple bonds to itself and other atoms. These compounds can be reactive enough to do all sorts of interesting chemistry, but stable e... |
[
"Is it possible to gain more than one pound of weight after eating one pound of food?"
] | [
false
] | [deleted] | [
"No. Even with a perfect 100% efficiency of conversion (which is not possible) the best you could do would be one pound. Exceeding that is impossible due to ",
"http://en.wikipedia.org/wiki/Conservation_of_mass",
"."
] | [
"You took in 1 pound of matter. How would your body convert 1 pound of matter into >1 pound of matter?"
] | [
"Sort of.",
"For example, salty food can make you retain water longer than you normally would. If you got on a scale 4 hours later, you might weigh 1.1 lbs. more than you would have if you hadn't eaten."
] |
[
"How does seedless produce get planted and reproduced?"
] | [
false
] | null | [
"There are different cultivars of watermelon that have different chromosome counts? That sounds like an extreme variation within one species (wait, are they even still one species?). How did this happen?"
] | [
"There are different cultivars of watermelon that have different chromosome counts? That sounds like an extreme variation within one species (wait, are they even still one species?). How did this happen?"
] | [
"A regular watermelon has 22 chromosomes. Using Colchicine makes the watermelon have 44 chromosomes. \nBreeding the first watermelon with the second creates a watermelon with 33 chromosomes. They technically have seeds, those little white soft ones that you don’t even notice are there, they just don’t fully develop... |
[
"Can plant roots penetrate a sheet of rubber?"
] | [
false
] | null | [
"Yeah. Seed lands in crack of a sidewalk, the roots begin to spread, water gets in the cracks and freezes expanding the cracks even more, etc. That's how it breaks down isn't it?"
] | [
"Hmmm...what I meant was, if you have an inch-thick sheet of rubber, and cover that in 5 feet of dirt, and plant seeds in the dirt on top of the rubber, will the roots of the seeds eventually penetrate the rubber or will they grow around it?"
] | [
"Sidewalks and roads (pretty much anthing made of rock) break apart after plants dig their roots in and grow bigger",
"Oh really?"
] |
[
"Do we experience less gravity during day time, because of the pull from the sun counteracting Earth's gravity? How big is this effect?"
] | [
false
] | null | [
"Correction: the sun also pulls on the earth, and this will greatly reduce the effect of the sun's gravity if you were to stand on a scale on earth (even though the sun is pulling you up, the earth is also being pulled up towards you. The residual effect is the difference between the sun's gravity at the surface vs... | [
"There is a very small effect due to the relative positions of the sun and the moon (mainly the moon), but it's not due to their direct pull on us but rather due to the reshaping of the Earth due to the tidal influence of those bodies, which modifies the gravitational field by about a part in ten million. See the g... | [
"This is wrong. I also once thought this and tried to measure the difference in gravity using very sensitive equipment at work (",
"by a bond tester",
") lifting a weight repeatedly during the day and the night. The tester is accurate enough to eliminate effects like temperature on the measurement. I found that... |
[
"Does rainwater really clean the air?"
] | [
false
] | [deleted] | [
"Water condenses around little specks of dust and dirt in the air, so it does get those little bits of matter out of the air. ",
"Acid rain has nothing to do with the dirt in the air. It's dependent on how much carbon dioxide is in the atmosphere. More carbon dioxide means the rain becomes more acidic"
] | [
"Look at air quality levels in your local paper, watch what happens after it rains. Particulates and NxOx molecules are certainly \"cleaned\", and any local paper can demonstrate this.",
"Acid rain is caused by sulfur and NxOx reacting with the water to produce sulfuric and nitric acids. Again the rain is clear... | [
"I'll look into that, but I seriously doubt my local newspaper would have any detail more elaborate than \"bad air day\" and \"good air day.\" The city I live in is seriously lacking in people who would understand any more detail than that. And I'm not saying that to be rude. It's actually true. "
] |
[
"When you break a bar magnet in half, it reforms north and south poles. The process repeats with additional breaks. Why, and how far \"down\" will I continue to get these magnetic poles?"
] | [
false
] | I understand that magnetism is basically formed by the uniform up or down spin of electrons, ( I could be wrong about this. I'm not even close to an expert.) If I'm correct, why does breaking a magnet cause these electrons to re spin in the appropriate configuration? Also, if I break a magnet in half, and then again and again... at what point will I stop seeing opposite poles? | [
"You are thinking about this the wrong way.",
"Think about magnets likes legos. North is the \"top\" of the lego with the little circles (male side), and South is the bottom of the lego with the cavity (female side).",
"At what point does the lego \"switch\" from the top to the bottom? This question doesn't rea... | [
"They don't re-spin. ",
"Think of the smallest \"unit\" of magnetism as pointing one direction. One direction it points will be \"north\", and the other is \"south\".",
"This is a fundamental aspect of magnets (di-poles). ",
"When you add a bunch of these units together facing the same direction, their streng... | [
"Individual electrons have a magnetic field. So far as we know, the electron is a truly fundamental particle and there is no way to divide it further. ",
"It might (and by might, I mean probably not) be possible to have a ",
"magnetic monopole",
", which would be like a north-only bar magnet. "
] |
[
"Is the CMB cold spot legitimate proof of the existence of a parallel universe?"
] | [
false
] | I've read that many physicists/astronomers believe that cold spots in space are imprints to other universes. Also what would a cold spot look like in person? Just vast emptiness or could there actually be a wormhole-like structure in that area? | [
"None of those things, it's just a place in the sky where the CMB is slightly colder, as is expected from its statistical fluctuations."
] | [
"Note that the difference between a cold spot and a hot spot in the CMB is ",
"0.0002 Kelvin",
". There is nothing interesting there to observe. The spots are no proof of a parallel universe but are grounds for hypotheses."
] | [
"The non-Gaussian cold spot detected in wavelet space in the WMAP 1-year data, is detected again in the coadded WMAP 3-year data at the same position (b = -57, l = 209) and size in the sky (around 10 degrees). The present analysis is based on several statistical methods: kurtosis, maximum absolute temperature, numb... |
[
"In theory, would it be genetically possible for two humans to repopulate the earth?"
] | [
false
] | Say a man and a woman are forced to repopulate our species after an apocalyptic event. Would genetic defects remain a major problem even after 10,000 generations++? How diverse could we become genetically? | [
" yes this could happen. The bottleneck is so slim, however, that it really remains up to chance. It really depends on how many recessive alleles are present in the founders and how deleterious these alleles are. Consanguinity has led to all sorts of genetic diseases that still affect populations today (hemophilia ... | [
"If you have a limited number of spaces on a space ship, you raise a very good point. By sending more females than males, you loose genetic diversity, but you gain in number of children that grow to childbearing age.",
"But as long as we are going scifi, you send a 100% female crew with a vast supply of frozen sp... | [
"maybe my post is best suited for this question! You need (on average, for any species) 4169 individuals but the conservative estimates for mammals are around 7000 and there's only direct evidence for 12000 or so. ",
"http://www.sciencedirect.com/science/article/pii/S0006320707002534",
"since these are individu... |
[
"How much orbital debris needs to accumulate around the Earth before we start forming rings that we can see from the ground? How long will this take?"
] | [
false
] | Is this even possible? | [
"Search for ",
"previous answers to your questions",
" before you post them :) "
] | [
"Oops. I usually do, but I forgot this time. Sorry about that!"
] | [
"Well, your question does specify a ",
" ring, so forgetfulness aside, your question is different. In light of the provided link, though, the answer seems to be the same \"no,\" but slightly more emphatic due to the extra requirement of visibility. "
] |
[
"can your hands \"prune\" in the salt water of the ocean?"
] | [
false
] | is this phenomenon caused by osmotic pressure, which would mean that you never prune if the water is saltier than your body, or does it work through some other mechanism that can work regardless of salinity? | [
"It's not caused by osmotic pressure, it's a regulated neurological phenomenon. If you cut the nerves to the hand, you don't prune. If you cut the blood supply to the hand, you don't prune. If it was osmotic, why does it only happen on the fingers and toes, and not on, for example, the forearm or chest?",
"I don'... | [
"Not a dumb question at all - the leading ",
"mechanism",
" involves electrolyte balance so it's quite reasonable to hypothesize that it works differently in salt water - from first principles of osmosis one would expect a difference. My experimentation-as-surfer (er, anecdotal evidence) is that the end result... | [
"not everyone can just go in the ocean whenever they want, thanks"
] |
[
"Is it true that certain foods can increase your short term mental alertness?"
] | [
false
] | [deleted] | [
"I had a HS teacher do the same with me and as I have judged science fairs, this is a common project for young kids (give some friends peppermint and see if they remember a list of words better than controls).",
"The claim for peppermint seems to be more in the smell as opposed to eating it. ",
"Here is one re... | [
"And its actually worse than that. Checkout table 1. They measured 17 variables (and possibly others not listed) and for each variable did three tests (control vs mint, control vs ylang, and mint vs ylang) and found 7 \"significant comparisons\" at the p<0.05 level (you would naively expect about 3 by chance). A... | [
"I've heard these things as well but I've never seen any data to support it.",
"You already mentioned caffeine, and that is basically the only food-product that I know that temporarily increases cognitive functioning. "
] |
[
"If the strong force will pull protons together just as strongly as neutrons, why don't we see nuclei with just 2 or 3 or more protons without any neutrons? Why aren't there any helium ions with no neutrons?"
] | [
false
] | null | [
"The diproton does exist. It is very unstable.",
"https://en.wikipedia.org/wiki/Isotopes_of_helium",
"While the strong force is strong, it still competes with the electromagnetic force. So protons still repel each other. This is one of the reasons why larger nuclei have more neutrons than protons. "
] | [
"Something like ",
"this",
"? There is some evidence for dineutrons. The problem for neutrons is that they are not the lowest bound state. They want to decay into protons. That is why free neutrons decay. Being in the nucleus \"stabilizes\" them. The modes of decay become limited and they are essentially p... | [
"A neutron is not an electron and proton stuck together any more than a proton is a neutron and a positron stuck together. A neutron is two down quarks and an up quark. A proton is two up quarks and a down quark. Neither of them have any electrons or positrons."
] |
[
"Massive bodies orbit in conic sections under Newtonian gravity. What shape would a photon's orbit be?"
] | [
false
] | Assuming it makes sense to think of photons as bodies of constant speed and ignore relativistic effects. Does the shape of the orbit of such a body have a name? | [
"There is no consistent way to talk about photons in Newtonian physics, which makes sense since they are quantum mechanical objects after all. Specifically, there's really no such thing as a massless object in Newtonian physics. I suppose the best you can say is that if m = 0, then the net force acting on that obje... | [
"You asked about how photons orbit in Newtonian gravity and prefaced the question by noting that ",
" objects orbit in conic sections. Well, ",
" objects don't exist in Newtonian mechanics, but if they did the best you could say is that they travel in straight lines.",
"Now you seem to be asking about orbits ... | [
"As I have said ",
" times, photons do not exist in Newtonian mechanics. At best you can say that since they are massless they are not deflected by any forces whatsoever and so their orbits are just straight lines. If your simulation is not based at all on GR, then I have no idea what this simulation is intended ... |
[
"How fast does something need to spin to look like it's not moving?"
] | [
false
] | I was looking at a D20 (20 sided dice) and was wondering how fast it would need to spin for it to look like it was still? Would it be possible? This would be looking directly at at, not through a camera. | [
"There is no definite answer to your question. Despite others have mentioned movie theaters as a \"proof\", it is not that simple. It depends on several factors for individual images to be fused into a continuous movement. Among others, like e.g. attention, these factors are general brightness and contrast. It work... | [
"Eye's don't see in FPS, they see a continuous stream of light. It's been proven that trained eyes are capable of distinguishing a single different frame (with enough detail to identify what the frame was) out of 200 frames shown in a single second. As another user stated, it's simply around 30 FPS that movement be... | [
"Eye's don't see in FPS, they see a continuous stream of light. It's been proven that trained eyes are capable of distinguishing a single different frame (with enough detail to identify what the frame was) out of 200 frames shown in a single second. As another user stated, it's simply around 30 FPS that movement be... |
[
"Why can some people seemingly fall asleep on command while others can hardly sleep at all?"
] | [
false
] | [deleted] | [
"I would love to hear an answer on this as well. I am able to fall asleep very easily, and my wife takes an hour or two to really fall asleep. Since she's been pregnant, (20 weeks or so,) she falls asleep on command, and we talk about why this is all the time. While not all that scientific, I've always thought i... | [
"Knowing why/how would be interesting to know. A \"cure\" would be great. I really envy my gf, she can start snoozing within a couple minutes of laying down, while I lay awake, miserable and tired."
] | [
"This is not a science answer, but from personal experiences it really seems genetic. You should conduct a survey and ask your friends who have varying levels of difficulty sleeping if their immediate family members are the same way. I'll expect a full report in 2 weeks."
] |
[
"How does Optical Image Stabilization work in an expensive camera lens?"
] | [
false
] | To me, the image appears more smooth as if controlled by a gyroscope, but I know that is not exactly how it works. Does anyone have an engineering insight on this? | [
"It isn't typically accelerometers. Such MEMS devices are relatively new. Most established camera systems such as Canon's IS use gyroscopes.\nA lens group mounted in the gyro resists camera shake redirecting light ",
"Here is a video of the IS lens in action:\n",
"http://youtu.be/C60ehMe3wQ8"
] | [
"looking back at my sources, I have no idea why I said accelerometers. I must have been out of it. ",
"Sweet video"
] | [
"Every company does it a tad differently, but in general, they all work on the same principle of using accelerometers to detect movements and adjust either an element in the lens (if it is lens based) or the actual image sensor in the camera itself.",
"Nikon has a relatively nice page explaining the technology. N... |
[
"If joules are understood solely as energy, how can they be negative?"
] | [
false
] | [deleted] | [
"It depends on context. If you have some process that involves energy, like a chemical reaction, negative energy often represents the amount of energy ",
" necessary for that process to take place. Another example is atomic or nuclear binding energy, which is often treated as negative. For instance, the inner ... | [
"If you're talking about ",
"enthalpy",
", then it has a very important meaning in distinguishing exothermic and endothermic reactions."
] | [
"The difference in energy between two states, for example."
] |
[
"Can I plug a generator into the wall socket to power everything on that line"
] | [
false
] | If I were to take a generator and plug it into my wall socket when the power is out would everything on that breaker be able to receive the power and could I power things on other breakers. I am not trying to do this just more curious if I'm thinking of this correctly. | [
"No it wouldn't work. Your branch breaker shares a bus with all the other branches in your house so you'll be trying to power your entire house off the 15A circuit your generator is connected to. Maybe if you turned off all the devices that you don't wish to use (don't forget the permanent devices like central air!... | [
"Assuming you disconnected the line (by turning of the relevant breaker), it should work after some fashion. But remember that wall sockets aren't dimensioned to drive an entire line, so trying something like this could easily cause an electric fire."
] | [
"Yes, it will power all the lines. The power will flow back though the circuit breaker to the mains distribution and the other circuit breakers.",
"You would have to open the main circuit breaker because if power comes back it will most probably desyncronize your generator and possibly destroy it (very dangerous)... |
[
"Benificial autocanibalistism in extreme survival situation?"
] | [
false
] | So the hypothetical situation is this: you are stranded on a rock in the middle of the ocean with no food (this includes a lack of all flora and fauna inhabitting said rock) but ample rainwater. The rock has worn away in a manner where it is impossible to fish without permanently returning to the ocean, which would be a problem if you had a boat but you don't. Given that you have the supplies and know how to amputate a limb with minimum loss of blood, and nullify any infection would there be any benefit in doing so and eating said limb? I know this is kind of strange but once a question pops in my head it is hard to let go... | [
"The inflammation and reaction your body would have to losing a limb from sawing it off would far outweigh any benefit from eating your limb. Also, the body is already reabsorbing the proteins in your muscle for fuel, so theres no real need to do it through your mouth/stomach. "
] | [
"Layman here but this is an easy one to tackle.",
"Your cells do that automatically as part of their normal metabolic processes: they often breaks down complex molecules they're \"made of\" to extract energy in order to sustain themselves if the calories intake is insufficient (some cell cannibalism/dead cell rec... | [
"Your's and mustfndnewname's points are ones i have considered as well, i suppose i should have worded the question better (Can it prove to be more benificial to canabalize a part of yourself rather than allow yourself to emaciate.) I hadn't thought of the fact that your body would be uniformly non-nutritious thoug... |
[
"How can a Half Blood Moon exist?"
] | [
false
] | On 24 March 2022, at around 3:00am, from the UK, I could see a red half-moon. At first I thought "Oh must be a lunar eclipse" before double-taking and realising it was almost a half moon (just coming into third-quarter). (this picture doesn't actually do it any justice, it was much redder). I did some research to see if there was a way the moon could appear this way somehow, and I also tried googling it to see if it could have been some sort of atmospheric disturbance or something, like the same way the sun appears redder in the sky at sunset and sunrise, but I didn't see anything related to the moon. The moon wasn't on the horizon, however it was low, but not at a height you'd expect to see such a dramatic change in colour. Also, as the moon rose in the sky, it stayed red. What am I missing here? | [
"It's only possible to have a Lunar Eclipse during a Full Moon - because that's when the Moon is on the far side of the Earth from the Sun - and the 24th of March was a slightly over half Moon, as in your picture. Though you ",
" get half-red half-black moons, but the black shadow has to curve the other way. If y... | [
"Have a look at this article from the Guardian:",
"https://www.theguardian.com/uk-news/2022/mar/16/saharan-dust-shifting-across-europe-hit-britain"
] | [
"That's an interesting article. The photo was actually taken in the north of the UK though. I do believe it to be an atmospheric phenomenon of some sorts however."
] |
[
"Is there a limit to how small a star can be? If so, what is the theoretically smallest star possible and why?"
] | [
false
] | null | [
"About 80 times the mass of Jupiter. Below that, they don't have enough mass to get the intense heat and pressure in the core required to fuse hydrogen. These objects are called \"brown dwarfs\", and generally look more like ",
" Jupiter than a star. The line between a small brown dwarf and a large gas giant is a... | [
"Astro physics put in terms I can understand. Thank you sir!"
] | [
"Here's my take. We want an object that is massive enough that when we are on the surface we cannot jump up to reach escape velocity. It needs to be made of a realistic material that we can obtain and put on its own. The densest such material is Osmium and it'll lead to the smallest radius. The highest vertical jum... |
[
"How is a genome built?"
] | [
false
] | Sorry to bring religious apologetics into askscience, but I was watching video and, while logical refutations for the majority of the annotations came to me easily enough, I found myself stumped trying to find literature that could help me understand the mechanics which allow a genome to expand (the point stating the difference between the genome of the simplest bacteria and the relatively complex human genome). I get the feeling there's already a pretty solid explanation or ten but I'd appreciate it if anyone could point me in the right direction. | [
"What do you mean, expand? Like in size, e.g. 3 billion base pairs vs 1 billion?",
"Well gene duplication events copy and duplicate a region of a chromosome. These events have occurred extremely frequently and have become a major source of evolution. There are lots of different mechanisms that can lead to this- \... | [
"It was indeed."
] | [
"That's pretty much what I was trying to ask :D",
"Thanks for responding so clearly. This leaves me with a number of phenomena to investigate...Wikipedia here I come."
] |
[
"Dear AskScience, is sound \"real?\""
] | [
false
] | We're all familiar with the old question: If a tree falls in a forest, and nobody is around to hear it, does it make a sound? Is it possible that we can answer this question through reference to the physics of sound and the biology of hearing? Sound is vibration. Our ears are sensitive to certain vibrations, and when we come in contact with those vibrations, our ears alert our brains to their presence. "We" then "hear" the corresponding sound. (The distinction, in discussions like these, of brain and self is always extremely baffling.) My question is, is there anything objectively "correct" about the sound we experience in response to a given vibration, or is it merely the product of a fixed, but ultimately arbitrary, convention of evolution - a code, or translation, if you will? Obviously the sounds are with the vibrations, and the whole system is self-consistent. If some hypothetical extraterrestrial scientists were studying the human brain and they (somehow) knew what one vibration sounded like to us, they could reasonably deduce what other vibrations would sound like to us. But is it not also possible that those same aliens would experience those same vibrations in an equally self-consistent, but wholly different way? If this is indeed the case, then, in my opinion (as a humble Philosophy undergrad), a tree falling in a forest make a sound. It makes vibrations. Sound is something that's heard - the subjective product of the objective vibrations filtered through and translated by our neurological hearing apparatus. If this is correct, then the other old philosophy cliche - how can you and I be sure we experience color in the same way? - would apply equally well to hearing. Thoughts? | [
"Isn't it really just a matter of definition? Settle on a definition and you have your answer."
] | [
"You're just playing with definitions. Is sound real? If you define sound as vibrations in the air, it is. If you define it as some hard-to-decode neural pattern, sure. If you define it as a thought, well, that depends on if you define thoughts to be real.",
"Anyway, if you intend to go down this route, it helps ... | [
"I think you are looking for ",
"/r/askphilosophy",
".",
"Our ",
" is our interpretation of vibrations in the air. What you define ",
" to be is largely up to you."
] |
[
"Is there any sort of evolutionary explanation as to why humans find baby animals cute?"
] | [
false
] | There is something about baby animals that invokes a deep emotional response in humans. You'd think that a baby animal would be seen instinctively as as easy catch for dinner. But instead, we want to pick them up and hug them. Other predatory animals seem to have no problem chasing after a baby animal of a different species. And humans don't have a problem chasing after an adult animal for food. I've always wondered about this. Perhaps because if humans were to kill off baby animals, they couldn't reproduce and there would be a shortage of food in the future (thinking in terms of more primitive humans in localized populations)? Thanks | [
"They have the same traits (such as large eyes) that make us think human babies are cute."
] | [
"I would guess that not going derpy over every infant is the learned behavior. People generally don't like strangers fawning over their babies, so you learn not to. Pets are different. "
] | [
"I would guess that not going derpy over every infant is the learned behavior. People generally don't like strangers fawning over their babies, so you learn not to. Pets are different. "
] |
[
"If measurement causes the wavefunction to collapse, and everything is constantly interacting with everything else in the universe via gravity, why haven't all wavefunctions collapsed all the time?"
] | [
false
] | [deleted] | [
"Crudely, wavefunction collapse means the following. You allow your quantum system S to interact with a set of degrees of freedom M. The interaction entangles the state of S with the state of M, so that the probability distribution of some observable OS of S are correlated with observable OM of M. But perhaps you d... | [
"EM is approximately a trillion trillion trillion times more powerful than gravity. Even on earth, gravity effectively doesn't exist when compared to electromagnetism. "
] | [
"EM is approximately a trillion trillion trillion times more powerful than gravity. Even on earth, gravity effectively doesn't exist when compared to electromagnetism. "
] |
[
"The speed of light and earth like planets"
] | [
false
] | When science searches the cosmos for "earth like" planets, are they actually searching for planets with a similar make up as ours? If we are, how do they figure out which will be earth like considering that the speed of light causes them to see so far into the planets "past"? | [
"From what I've heard/seen, most the planets we've found are on the order of tens to hundreds of light-years away, meaning we're look at them only a few hundred years in the past. ",
"Example: ",
"Here's",
" a 600 light-year away planet",
"After a little googling I found an ",
"article",
" that has some... | [
"Two answers to your question!",
"As snailbotic pointed out, all of the planets we are looking for/found are rather close to Earth. I don't know the exact number, but I would venture a guess that they are all within 1000 light years. ",
"When we look for \"Earth-like\" planets, we're not necessarily looking tha... | [
"In addition to the other responses, I'd like to point out that the vast majority of exoplanet researchers aren't looking for \"earth-like planets.\" Of course, finding such would mean instant fame. But most researchers have their own topics of interests: things like hot jupiters, mdwarfs, multiple-planet systems, ... |
[
"Why don’t we use salt water for toilet water? Wouldn’t it save millions of gallons of freshwater?"
] | [
false
] | null | [
"Saltwater is more reactive and corrosive than fresh water, for one. Harder to maintain, I'd expect.",
"Also, you would still want fresh water to your house for showering and cooking, so you'd have an additional set of pipes running to each building."
] | [
"As others have said, there are problems with salt water.",
"The solution is \"grey water\". This is water that is relatively clean but not drinkable. Think rainwater, or what goes down the plug in your shower or bath, even what comes out of your washing machine. All of this is perfectly good to flush a toilet wi... | [
"In extreme cases it is used. For instance Hong Kong has a dual water system. ",
"https://en.m.wikipedia.org/wiki/Water_supply_and_sanitation_in_Hong_Kong"
] |
[
"Can we make sounds with our vocal chords that are not in the audible frequency range?"
] | [
false
] | null | [
"It depends how you define \"sound\". Do you mean the fundamental perceived pitch, or can we include the highest frequency present in the vibration?",
"If you can make a clicking sound, a click can approach a ",
"dirac delta function",
", which has energy at every frequency. It is the identity operator in tim... | [
"I should add that this is not the only possible way to make an ultrasonic vocalization. Just showing that at least one is possible."
] | [
"Just an interesting aside - there is ",
"evidence",
" to suggest that those who are \"hearing voices\" are making subvocalizations in line with whatever it is they're hearing. Essentially, your vocal cords are demonstrating subtle activity but not actually producing audible sound, while you hear the voices int... |
[
"Why do the containers of vacuums need to be strong?"
] | [
false
] | null | [
"Yeah, that's it. You need your chamber to be able to withstand the inward pressure force, or else it will implode."
] | [
"PSI stands for pounds per square inch. Just estimating the size of that tube to be 10 meters in length and 1 meter in diameter, its surface area is 48695 in",
". Assuming the pressure difference between outside and inside is 14.5 PSI, the force acting on the tube is over 700000 pounds."
] | [
"hmmm, good point. Theoretically though, if you could get a material that could withstand an inwards force of 15psi (as an example) would that be sufficient to prevent an implosion? Or are there more forces at work>? "
] |
[
"Does a person using a skateboard expend less energy than a walking person traveling the same distance?"
] | [
false
] | Yes, I know. Strange question. But I was watching a neighbor pass by my house on a skateboard today, and I started wondering about the physics of it. Obviously, he was moving between points A and B on his journey faster than he would be walking. But then again, he also has to occasionally use one foot to push against the ground several times to keep the momentum of the skateboard moving forward at a higher speed than if he was just walking. My question is basically is he ending up expending the SAME amount of total energy by the "pushing" of his one foot while using the skateboard as he would if he was just walking the same distance traveled using two feet? Assume all other things are equal, as in the ground being level in the comparison, etc. My intuition says there is no such thing as a "free energy lunch". That regardless of how he propels his body between two points, he would have to expend the same amount of energy regardless whether he was walking or occasionally pushing the skateboard with one foot. But I'm not sure about that right now. Are there any other factors involved that would change the energy requirement expended? Like the time vs distance traveled in each case? EDIT: I flaired the question as Physics, but it might be an Engineering question instead. EDIT 2: Wow. I never expected my question to generate so many answers. Thanks for that. I do see now that my use of the words "energy expended" should probably have been "work done" instead. And I learned things I didn't know to begin with about "skateboards". I never knew there were...and was a difference between..."short" and "long" boards. The last time I was on a "skateboard" was in the late 1960's. I'd hurt myself if I got on one today. | [
"To be fair, it is unlikely they were using subjects who weren't experienced with walking."
] | [
"A study was done two years ago by Colorado State University for 15 experienced longboarders.",
"\"The gross metabolic cost was ~2.2 J kg(-1) m(-1) at the typical speed, greater than that reported for cycling and ~50% smaller than that of walking.\"",
"http://www.ncbi.nlm.nih.gov/pubmed/25085605"
] | [
"Just noticed this study was done on longboards. They are overall a much smoother ride and require much less work, so I'd be interested to see this study done for a short board. "
] |
[
"Why is Fluorocarbon hydrophobic?"
] | [
false
] | If I understand it right, hydrocarbons are hydrophobic because of the non-polar interactions. But what makes Fluorocarbons MORE hydrophobic? Fluor-carbon interaction are very polar aren't they? so wouldn't that make them soluble in water? | [
"Great question!",
"Your most common PFC is CF4. Draw a Lewis structure of this molecule and notice that the four C—F bonds are symmetrical about the central carbon atom. You’re correct that each of these bonds is polar, and ordinarily that does make a molecule hydrophilic, but in order to be hydrophilic the ",
... | [
"Short answer: My guess would be that fluorocarbons are more hydrophobic than hydropcarbons because FC's are bigger. ",
"Here's a paper",
" which supports that, stating, \"[T]he extra work of cavity formation to accommodate a fluorocarbon, compared to a hydrocarbon, is not offset by enhanced energetic interacti... | [
"Ok thank you,",
"But what properts makes Fluorocarbons MORE hydrophobic than hydrocarbons? I am making a presentation about Fluor in skiwax and why is is hazardous. But I am also gonna explain why Fluor works so good as a skiwax. That must be because it is very hydrophobic, right? I’ve also found out that paraff... |
[
"How do I know what atomic mass is correct on the periodic table when different tables have different atomic mass for certain elements?"
] | [
false
] | I am home schooling my 8 year old son and would like to start teaching him the elements on the periodic table. I have made flash cards for all 118 elements on the periodic table including symbol, atomic number, element name and atomic mass however different periodic tables seem to have different atomic mass for certain elements. I have added the other name and symbol for the elements that are known by two names, like 112, Copernicium is also known as Ununbium, but am unsure as to which atomic mass I should attribute to the cards when I get different AM from different tables. Anyone able to tell me which table is most accurate? Thanks in advance. | [
"Don't make your kid memorize all the element masses to four decimal places. Do make him understand what the position of an element in the table can tell him about its properties, how to estimate molar mass from the number of the element, what the atomic shells will look like and what this means for reactions, etc... | [
"This.",
"The ability to read, comprehend, analyze, and ",
" information is an infinitely more useful skill to teach than ",
" rote memorization ever will be."
] | [
"Copernicium is the new name for 112. The previous name was a placeholder. Also, I wouldn't worry about those. They are synthetic. Focus on teaching the meaning of the mass. Also, the mass is based on isotopes and percent abundance in the world...so Carbon is actually different masses than what you see on the table... |
[
"Light and sound are both waves. Does light have octaves too?"
] | [
false
] | null | [
"Sidenote: ",
"If \"musical note A\" were defined to include every wave with a frequency of (440 * 2 ^ x) where x is an integer, then the 40th octave of A would be 483785116221440 Hz, which falls within the color red.",
"The \"41st octave\" (under this crazy definition), would be outside the visible spectrum."
... | [
"An octave is \"the interval between one musical pitch and another with half or double its frequency\" ",
"Source",
"You can have double or half the frequency of a certain wavelength of light, so sure. Also see ",
"\"Electromagnetic spectrum\""
] | [
"The relevant numbers are frequency, not wavelength.",
"http://www.wolframalpha.com/input/?i=frequency+of+visible+light",
"But yes. 450 to 750 Terahertz",
"Also interesting, there's a weird gap in our understanding and manipulation of electromagnetic frequencies just above radio waves and just below infrared ... |
[
"How far off is GATTACA style engineering?"
] | [
false
] | null | [
"I don't think its a good idea to play with that kind of stuff in our lifetime. With only a handful of semi-successful transgene tested in humans, the idea of engineering many your of kid's genes presents a lot of unknowns that might be better tested in mice first. I'll note that 4 of the ten patients in the famous... | [
"So probably not in my child bearing life time?"
] | [
" to get it past the ethics committee."
] |
[
"Why are galaxies shaped like spirals? Why doesn't the spiral structure stretch out and disappear after a few galactic revolutions?"
] | [
false
] | The center of a galaxy must be rotating many times faster than the outer limbs due to the laws of angular velocity, right? (Like how Mercury rotates much faster than Earth... or is that a false analogy?) It would seem like the neat spiral pattern would pretty quickly get spread out into longer and thinner bands, until they were eventually unrecognizable. Why doesnt that seem to happen? | [
"Short answer: Because dark matter!",
"The short answer should have been \"density waves,\" because the spiral structure would be possible with or without dark matter. Dark matter does affect the rotation of a galaxy, but it is not responsible for the spiral shape (nor does the observed rotation curve - based on ... | [
"Short answer: Because dark matter!",
"The short answer should have been \"density waves,\" because the spiral structure would be possible with or without dark matter. Dark matter does affect the rotation of a galaxy, but it is not responsible for the spiral shape (nor does the observed rotation curve - based on ... | [
"There are many ways you can get spiral structure. Because the inner gas and stars take less time to orbit than the outer gas and stars, any structure will get sheared out into a spiral-ish shape. So it's quite common to get things like ",
"flocculant spirals",
", where instead of a couple of big spiral arms, y... |
[
"G-force, pushing vs. pulling? can you tell?"
] | [
false
] | Hi! I just listened to a podcast discussing cars, and I couldn't quite grasp their statement, which was: Some people prefer engines in the back (Porsche f. ex.) instead of the front (most normal cars) not just because of the driving physics (weight distribution, traction etc.), but because they enjoy the feeling of being pushed rather than being pulled. Made me think - is there any noticable difference? Is it possible in a blind test to determine if you are being pushed or pulled? For experimental purposes, let's eliminate factors such as rear wheel drive vs. front wheel drive vs. four wheel drive, suspension, etc. Every voice in my head says there is no way to tell the difference, but it would be nice to hear your thoughts. | [
"Any rear-wheel drive car is still ",
" you, regardless of where the engine is. ",
"To flip it on its head, if a rear-engine car were front wheel drive, would it still be pushing you?",
"It's not a question of where the engine is converting chemical energy into kinetic energy, it's where this kinetic energy i... | [
"Yes, you can tell where the weight of the engine is when you're accelerating and cornering, but when they're saying 'pushing vs pulling' I have to think they're talking about whether a car is front wheel drive or rear wheel drive. "
] | [
"Interesting question. There's already good answers in this thread, I just want to touch on something else.",
"I don't think you'd be able to tell the difference between pushing or pulling. The reason I think this is the case is because the force applied by the road onto the tires and then to you the driver. But ... |
[
"If a fruit like a pear is grown in a no gravity condition, will it still be pear-shaped?"
] | [
false
] | [deleted] | [
"Some pears are round. Do a google image search for \"round pear\" and you'll see them. Further research showed a specific pear that's round called ",
"pyrus pyrifolia",
".",
"Further exploration yielded this ",
"PDF paper",
" detailing a pear-shaped tomato being linked to the genes. Now, this article qui... | [
"Yes, the genetic makeup of the plant determines the shape of the fruit. But gravity acts upon the plant while it produces these fruit. You don't know how this influences the shaping of the fruit, maybe this shaping process depends on gravity. The typical pear shape is what the plant produces under the conditions f... | [
"Gravity doesn't do much at all.",
"Read my first level reply. I'm the son of a apple and pear farmer, I've seen pears grow in every direction, including entirely upside down, end result is always the same."
] |
[
"If the symptoms of COVID-19 are so similar to flu/cold symptoms, how did doctors discover this was a brand new virus?"
] | [
false
] | null | [
"COVID symptoms are not really similar to flu/cold. They tend to be more severe. The doctors saw a bunch of very severe flu-like illnesses and got suspicious. ",
"There are two major misunderstandings floating around, making people think that this isn’t as serious as it is. ",
"First, public health people said ... | [
"And this is how jargon can cause miscommunication. The average person will interpret \"mild\" as nothing to worry about. Surely people versed in effective communication saw that coming..."
] | [
"i work in pharma/vaccine manufacturing. ",
"They are already doing this. Once we identified the genome of SARS-CoV-2 they begann identifying target proteins to make the vaccine. Then you have to make the vaccine, two ways of doing this, either making mRNA that codes for the protein or grow cells to create the pr... |
[
"Why doesn't our brain go haywire when magnetic flux is present around it?"
] | [
false
] | Like when our body goes through MRI , current would arbitrarily be produced in different parts of our brain which should cause random movement of limbs and many such effects but it doesn't why? | [
"The current produced would have to be strong enough to overcome our neuron's threshold for activation. All neurons have a base level of electric activity called a resting membrane potential, which is about -70 millivolts (mV). In order to cause that neuron to send an electrical impulse we must depolarize that sam... | [
"Electrical current doesn’t flow through nerves like it does in wires, where a magnetic field ",
" induce a current. Instead, it’s an active process involving the movement of ions across the cell membrane that occurs in a moving gradient down the length of the nerve, which a magnetic field does not affect in the ... | [
"This is all accurate in principle, but as an electrophysiologist I feel i should mention that plenty of neurons rest around - 60 to - 55mv. And while the depolarization threshold varies a bit by channel types expressed, I've never seen it as low as - 55mv, -35mv or higher is more typical."
] |
[
"If Mercury's year is only 88 Earth days, why is it's transit across the Sun so rare?"
] | [
false
] | null | [
"Mercury usually passes above or or below from our perspective.",
" I'm doing this on my phone's calculator while watching Dubs/Blazers so someone correct me if I screw any of this up. Quick math:",
"Radius of the sun is 695700 km. Earth to sun is 149.6 million km. Mercury to sun is 57.91 million km. Mercury or... | [
"While Earth orbits the sun every 365 days, Mercury orbits the sun every 88 days. However, Mercury's orbit is tilted, which means it will only pass directly between the Earth and the sun 14 times in the next 100 years. Aside from today, the next time will be in 2019 and after that, 2032.",
"I pulled this from a... | [
"It has to do with the orbit incline.",
"http://www.vox.com/2016/5/8/11612978/mercury-transit-watch-2016"
] |
[
"Why does light travel faster in a vacuum?"
] | [
false
] | If atoms are mostly empty space, and photons are infinitely small anyway, shouldn't they always travel at the same speed? | [
"Yes, but when going through a medium photons are being absorbed and retransmitted. This causes the apparent slowdown."
] | [
"Actually, classical electromagnetics is a worse way to explain the slowing of light. You can take the macroscopic view and work with flux quantities (B and D), but that doesn't actually really explain it at all. The microscopic view does, but you have to construct an infinite series of induced dipoles and scattere... | [
"The way it was explained to me was that waves are remitted in all directions and through interference and superposition the lightwave retains its direction of propagation."
] |
[
"Can we deduce any properties of an element from its emission spectrum?"
] | [
false
] | Edit: Thank you for the answers! | [
"You can get the nuclear mass. If you compare the emission spectra of different isotopes of the same element (e.g. hydrogen and deuterium) there are small differences in energy - the isotopic shifts. These can be measured with high precision and do give you the nuclear mass. ",
"I've done the experiment as an un... | [
"Theoretically, yes. Envision spectra are caused by transitions between different energy states of an atom. The wavelength of the emission, and to some extent the width of the line, do reveal a lot of information about the different energy states. It is theoretically possible to take that information and use it to ... | [
"I am currently going through Balmer Series in college and don't really understand what's special about those emission lines "
] |
[
"Is it true we know more about our moon than we know about our oceans?"
] | [
false
] | I hear this a lot and I just thought I'd ask this here. | [
"Yes, in that it is much easier to explore and learn about the moon then it is the oceans. Mostly in that the oceans are so complex. Only with modern technology have we really begun to understand how different factors interact in the oceans. One issue is that the marine science lags behind terrestrial science simpl... | [
"But that sounds like a relative thing, as in, it's a lot easier to know everything about a thumb tack than an amoeba. It may be more accurate to say that we can characterize the Moon more fully than we can characterize the oceans, but the total body of knowledge about the oceans is greater than the total body of ... | [
"As a geologist, I would say no. I typically file that statement under such phrases as, \"we only use 10% of our brains\" - something the general public considers fact.",
"When I consider how much mapping still needs to be done on Earth in areas that have been explored for over a century, it occurs to me that a c... |
[
"When thermite burns on ice why is there an explosion?"
] | [
false
] | The Mythbusters did this and didn't have a good explanation as to why. Video here: I've heard two explanation. Hydrogen being released from the oxygen and detonation or a Steam explosion. Neither seems to be wholly correct to me. As for a steam explosion I would think there would need to be a pressure vessel to contain the steam long enough to build pressure and there isn't one. For a hydrogen explosion again there would need to be something keeping the hydrogen in close until the air-hydrogen ration would allow a detonation as opposed to a simple burn off. So, do we know what causes this and if not, what do you think would be a viable experimental protocol to find out? | [
"It is a steam explosion. Breaking down of water molecules is not an instantenuous reaction, and it needs a certain catalyst. Instead, water evaporates very quickly, and as we know from Clapeyron's equation (ideal gas law), hot gas likes to expand, and it does so very quickly, releasing so much energy, that it's ab... | [
"The explosion you see in a ",
"grease fire with water in it",
" is also a steam explosion. No pressure vessel needed."
] | [
"Explosion is just a rapid gas expansion, that's all there's to it. There doesn't need to be a container in order for gas to explode, if enough hot steam is created. Following that logic, there would have to be a container in order for explosives to work, but that's not true. "
] |
[
"What is it with spinning?"
] | [
false
] | [deleted] | [
"Well, the short answer is that central forces are everywhere. In 3-d space in general there's no preferred direction, so forces like gravity and electromagnetism are emitted with spherical symmetry. ",
"Orbits happen with forces that point towards the center, like gravity or EM attraction between opposite charge... | [
"The electron can actually collapse to the center in some cases, unstable proton rich nuclei can actually undergo decay by \"electron capture\". Since the wavefunctions of inner electrons overlap with the nucleus, there is a small chance of a weak interaction where the electron is changed into an electron neutrino,... | [
"The electron can actually collapse to the center in some cases, unstable proton rich nuclei can actually undergo decay by \"electron capture\". Since the wavefunctions of inner electrons overlap with the nucleus, there is a small chance of a weak interaction where the electron is changed into an electron neutrino,... |
[
"How does the body generate heat?"
] | [
false
] | null | [
"In birds and mammals, the heat comes specifically from the mitochondria in the cell ",
" a series of spatially separated redox reactions called an electron transport chain, or ETC (thanks ",
"/u/onthisday420",
"!) to create ATP, which other cells use for energy, AKA, \"metabolism\". Some recent studies hav... | [
"So they really are power houses?"
] | [
"In birds and mammals, the heat comes specifically from the mitochondria in the cell breaking down glucose to create ATP",
"Not just glucose. Other substrates can be broken down/converted into pyruvate, such as triglycerides. These breakdowns/conversions also give off heat. "
] |
[
"What are the earliest known occurrences of depression? How was it recorded?"
] | [
false
] | Any answers?? Thanks! | [
"I've learned it's on mesopotamian clay tablets, with a description of symptoms and treatments - although it was handled by priests, since they thought it was caused by demonic possession or curses (by either a god or a human). Does trying to find out which cause \"applied\" in each case as early psychotherapy?",
... | [
"Layman comment: but I feel like there's references in medieval Europe to kings falling to deep malaise / melancholy.",
"Also would be interesting to look at early buddist philosophers and ask how they were so so early on the drop to realizing nothing is real in the way we think of it, and what biochemically may ... | [
"It was reported among the ancient Greeks, as was a treatment they sometimes used, throwing the patient off a short cliff into the sea. (I read about this many years ago when I wrote an educational monograph on depression for Bristol-Myers Squibb when they were launching the antidepressant nefazodone.) Presumably i... |
[
"Is a scientific theory speculation?"
] | [
false
] | Someone keeps telling me a theory is just speculation. I don't believe that is the case. Can askscience weigh in? Maybe with some credible sources? | [
"In science, there is a really big difference between Theory, as in Scientific Theory and theory which is what you'd use in everyday language. Let me illustrate this:",
"The roof is leaking, my theory is there is a hole in the roof.",
"While the average Joe, calls this his theory, it's what in science would be ... | [
"No, a scientific theory isn't speculation.",
"Let's put it this way. A speculation is a possible explanation based on what you observed. In scientific terms, this can be said to be a hypothesis. A theory is a hypothesis that has experimental and theoretical backing. That means that a theory is a hypothesis that ... | [
"Thanks."
] |
[
"How much time would a flight attendant 'gain' over their career?"
] | [
false
] | So I was talking to my aunt who said that she was on a plane that was the last flight of one of the attendants before she retired. She also commented that the attendant in question "looked every minute of 60 years old." Now I know that because of time dilation, she would have 'gained' a small amount of time by travelling at high velocities, but how much? Assuming that she was working as a flight attendant full-time for at least 30 years, would she have gained a few seconds or a minute of time or what? Would she legitimately be "every minute of 60?" | [
"There have been several tests that measured time dilation due to flight. ",
"A recent one",
" measured a shift of 246 ns on a trip from London - LA - Auckland - Hong Kong - London.",
"Let's assume a flight attendant makes a journey roughly equivalent to that twice a week, 45 weeks a year, for 40 years. ",
... | [
"The time dilation effect would have only a very minor impact, less than a second, so no."
] | [
"On michio kaku's \"sci fi science\" he had an interview with an astronaut that had spent 3 years in space, his life was extended with something shorter than .001 second, so the effect of it isn't that great"
] |
[
"Can someone please explain time dilation to me?"
] | [
false
] | null | [
"It's just foreshortening. Time isn't special, it's just another direction (like \"north\"). ",
"Einsteinian relativity unifies the concepts of \"motion\" and \"rotation\" -- as in, you're always zooming along at ",
" in some direction or other. If you're sitting at your desk, you're zooming directly \"later\... | [
"Have you seen this video by sixty symbols? It's quite understandable. ",
"http://www.youtube.com/watch?v=jlJNsRZ4WxI"
] | [
"http://casa.colorado.edu/~ajsh/sr/time.html",
"There is an interesting gif there that illustrates how the time appears. The blue ball, which is moving, sees the white ball as being a normal rate, but the red ball sees a difference between the two (red thinks that blue's is slower)."
] |
[
"Why does disinfecting a wound cause it to \"sting\"?"
] | [
false
] | Using first-aid spray, hydrogen peroxide, alcohols, etc. causes that sharp stinging feeling when applied to an open wound. I know this has to do with the death of bacteria, but why exactly does it feel like that? | [
"Intact skin has layers of dead cells that protect it, but when the skin is broken, tissues are exposed. If they come in direct contact with alcohol, they are damaged. Alcohol takes lipids out of the membranes of cells, allowing dehydration, killing your cells and thereby causing pain. "
] | [
"These disinfectants are essentially poisons. They kill cells, whether they are single cellular organisms, ore cells of a larger being. You feel a sting because the disinfectant kills some of your cells, but your body is perfectly capable of handling that. "
] | [
"Most of the reason is that peroxide is actually not a very effective disinfectant. It doesn't kill many bacteria, and also doesn't kill as many of your mature cells, which means you experience less pain.",
"A contributing reason is that H2O2 has a fairly short shelf life. If you've had a bottle of household pero... |
[
"I'm sitting in central Florida, where did the rain that is falling from TS Debbie come from. Did it evaporate from the gulf, or is it local moisture?"
] | [
false
] | null | [
"I think OP was asking not where the storm came from, but where the water itself came from. We've all seen satellite images tracking storms, and know they move across the water. But more specifically, does the water rise and fall into the sea, creating a chain reaction that fuels the storm, or is it literally a swi... | [
"Atlantic Tropical Storms are essentially just weak hurricanes. They form from evaporation of the warm ocean water off the coast of western Africa, and are then carried west by the tradewinds (a dominant easterly airflow) to wreak havoc on the Caribbean and Gulf region.",
"If it's raining in Florida, the humidity... | [
"The water is being pulled out of the Gulf, the heat of the water allows incoming air to evaporate large quantities of the ocean. The water is then uplifted through adiabatic processes(as well as the upper level low) and condensed as precipitation which falls over wherever it happens to fall.. ",
"For Debbie. the... |
[
"Can we create \"new\" organ systems?"
] | [
false
] | With stem cells, I am under the impression that you can kind of "zap" them into doing different tasks and becoming different types of cells. Does this mean that you can only zap them into being things that already exist, like liver cells or skin cells? Or are you actually able to make them do ANY job? If you can make them do anything, does this mean that we can create entirely new organ systems in the body to do completely new functions and ultimately allow us to directly evolve ourselves? I have mentioned this to people and for some reason they usually don't fully grasp what I am saying. When I say "new organ systems," think about the ones you already have. Digestive, Respiratory, blah blah blah. Each system has its own job to help the body survive. A new system would be an organ(s)/gland(s) that do something like..... notify you when you are near radiation? Or one that sends cells throughout the body to endlessly hunt/kill cancer cells? (im still working on good ideas for new organ systems lol..) But the idea is that you would be able to do some sort of function that you could never do before that would help you survive. Sorry if that last part was too simple. I have just had too many people require that extra explanation. | [
"Every cell in your body (that has DNA) has a set of recipes for every organ your body contains (probably some exceptions there too, since this is biology; I'm thinking gut microflora?). The thing is that most cell fates require the cells to go through a series of successive, irreversible ",
"differentiations",
... | [
"Stem cells can only differentiate into whatever the DNA inside them encodes for.",
"Creating a new organ system would be mostly pointless and incredibly difficult. However, if you applied extensive gene therapy to many, many stem cells, and then injected them into the person's body, it could be possible."
] | [
"Yes, we'd need to engineer the new organs. There are no instructions to follow other than those for the organs we already have. The body does not check for DNA when rejecting cells, it checks for other factors which stem cells can replicate."
] |
[
"Roast beef turns grey-brown when fully cooked, but smoked meat becomes red, instead. How does smoke change how the meat cooks? What's the chemistry of this reaction?"
] | [
false
] | null | [
"You might be referring to the pink smoke ring that can be found in smoked meats. This is caused by a reaction between nitrogen monoxide and carbon monoxide in the smoke and myoglobin in the meat. More information: ",
"http://amazingribs.com/tips_and_technique/mythbusting_the_smoke_ring.html"
] | [
"Roast beef is supposed to be red in the middle also but what most people see and eat that is labeled Roast Beef isn't Roast Beef or not very good Roast Beef. ",
"This is what good Roast Beef is supposed to look like",
"Roasting and smoking both use low heat but long cook times which browns only the outer layer... | [
"If you cook it long enough it will loose it red color but then all you'll have is ashes and chew sticks for your dog. :)"
] |
[
"What would happen if I fired a gun on the moon?"
] | [
false
] | null | [
"Because saltpeter (a part of gunpowder) has oxygen as a component, the gun will still fire and cause the bullet to move.",
"With no air resistance and lower gravity, the bullet would travel farther and faster than on Earth.",
"But as the escape velocity of the moon (~7,000 feet per second) is higher than the m... | [
"I doubt it'll be a huge difference. Compared to the pressures behind the bullet a drop of 1 atm pressure in front won't matter too much, especially considering the short time it spends in there."
] | [
"I wonder how much the lack of air resistance in the barrel would increase muzzle velocity. Some exotic cartridges can get muzzle velocities of 4-5,000 ft/s. I doubt it would get all the way to 7,000, but I wonder how close it could get."
] |
[
"How exactly are neutrinos and dark matter related?"
] | [
false
] | null | [
"Neutrinos are an example of dark matter because they do not interact with light. But the total energy of the neutrinos in the universe is very small, so they are only a very small fraction of the dark matter that exists. Also, we know that dark matter is \"cold\" and clumps together due to gravity based on many ki... | [
"The amount of neutrinos from the big bang can be measured indirectly: They influence the cosmic microwave background. No, there are not enough neutrinos around (at least not the type of neutrinos we know). There is also ",
"PTOLEMY",
", a proposed experiment to measure these neutrinos directly."
] | [
"They might not be. Neutrinos are an example of a particle which does not interact via electromagnetism, so they are proof of concept in a sense: we know dark matter doesn't interact electromagnetically.",
"Neutrinos, as observed, can't explain dark matter. But they show other possibilities."
] |
[
"Is my car engine more efficient on hot or cold days?"
] | [
false
] | Let us define "Hot" and "Cold" to be in the vicinity of 80 F and 30 F respectively. | [
"It depends on how long you're going to be operating it for, and if you live in the real world.",
"Cooler intake air will be more dense and have higher mass flow per piston-cycle. Getting more mass of oxygen into the cylinder will allow more fuel to be burnt, making each cycle produce more power (but also use mor... | [
"No problem.",
"So what happens, is, you get rapidly cooling exhaust. Cooler gas mixtures generally have higher kinematic and dynamic viscosity. They are also more dense.",
"Both of those result in making it more difficult for the fluid to flow.",
"Higher viscosity means that the fluid will essentially be 'st... | [
"You're probably going to get answers about Carnot efficiency but they will be wrong. Car engines are incredibly complex machines and are limited by a ton of factors before Carnot efficiency. Real world efficiency drops during the winter, but I am not qualified to talk about why"
] |
[
"Are there any known organism that is so photophobic that they can actually die from too much exposure to common sources of light?"
] | [
false
] | And no, I dont mean the heat that usually comes with most light source. I mean . And by "common" I mean not something that can only be produced in a lab or in space like gamma or x-rays. I mean sunlight or a torchlight. | [
"So related to your question, there was a famous tree in northern British Columbia called \"Kiidk'yaas\" or simply \"The Golden Spruce\". It had a mutation that would cause needles to die if they received direct sunlight even though the tree needed sunlight to survive. ",
"This tree managed to grow quite large du... | [
"The guy that cut it down was \"protesting the forestry industry\". The tree was considered sacred to the Haida Gwaii people of British Columbias West coast. He cut the tree in such a way that it would fall in the next big wind (\"a series of deep cuts\") in January 20th 1997, the tree fell 2 days later. He claimed... | [
"Lots of (most?) unprotected ",
"organisms will succumb to radiation damage after sufficient exposure to sunlight. See ",
"this study",
". Melanomas and the like will accomplish the same thing in humans and other unprotected animals."
] |
[
"Big rip question"
] | [
false
] | If the big rip is the ultimate fate of the universe, is it possible that dark energy's action on quarks could lead to some sort of spontaneous matter production (due to confinement)? Possibly to such an extent that such an event would resemble the big bang? I'm pretty sure I've made (many) mistakes or misunderstandings above so spare me no correction. | [
"If the big rip is the ultimate fate of the universe…",
"It isn't. At least, there's no reason to think it is. The \"Big Rip\" idea came out of a paper published last decade, 2003 or somewhere around there I believe, that started with the ",
" that the scale factor could go infinite in finite time. It was a wha... | [
"It's speculation, but not ",
" out of a hat speculation; their paper was based on rigorously showing that the scale factor ",
" diverge if dark energy exists and has certain parameters. Since dark energy is part of the standard model, and the parameters needed for a big-rip are within the error range of curren... | [
"Everything we know about the universe — which isn't everything there is to know about the universe, obviously, but it's an awful lot — says the scale factor will increase exponentially but that it will not diverge.",
"Just out of curiosity, do we know what value it will probably converge to? If so, what is it?"
... |
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