title list | over_18 list | post_content stringlengths 0 9.37k ⌀ | C1 list | C2 list | C3 list |
|---|---|---|---|---|---|
[
"Why was I told to decelerate before turns and accelerate through turns?"
] | [
false
] | [deleted] | [
"Come on Mr engineer!! You don't remember any of your physics courses? :P",
"But seriously, its simply centripetal force. Fc = m*v",
"/r. The centripetal force is directed outwards from the circle that you would make if you continued turning. This outwards force could flip the car over or cause it to lose t... | [
"In line with the question itself, most driving instructors will tell you to decelerate ",
" the turn, not decelerate during the turn until you hit the midpoint."
] | [
"You want to transfer weight on a motorcycle too. For one thing, the rear tire usually has a much bigger contact patch (it's thicker), so you want most weight on it. For another, slight acceleration in a turn will place both suspensions at middle point, i.e. at optimum point to provide stability."
] |
[
"when asteroids/comets pass near the earth, why don't we send stuff over for science?"
] | [
false
] | null | [
"Pretty much, everything we have in space is in some kind of orbit. Of course, satellites orbiting the Earth are in orbit (which is obvious), but even when we send satellites (or people) to the Moon (or Mars) they are still in orbit- an orbit called a transfer orbit. They are only under powered flight for a short t... | [
"Because being near the earth don't make it significantly easier to land stuff there. ",
"If we want to send payload to asteroid, we must match the orbits. It's much easier to match orbits if they are similar even if the asteroid is nowhere near the earth, than try to catch random asteroid that passes the earth 5... | [
"\"",
"Yes, this is generally correct."
] |
[
"Are there other problems like random/drunk walk and cross-product which have significantly different solutions depending on the number of dimensions?"
] | [
false
] | A random walk (drunkard's walk) in or dimension will 100%* at some point return to its starting point. In three or more dimensions, a random walk is not guaranteed to return to its starting point. Another example is the cross product, which is only defined in three and seven dimensions. There is no two-dimensional cros... | [
"How many ways are there \"to do calculus\" on Euclidean space? For dimensions 1,2,3,5,6,7,8,9,10,11,12,... there is only one way. For four dimensions, there are infinitely many ways to do so. These are called ",
"Exotic R",
" spaces.",
"Somewhat relatedly, the ",
"Poincare Conjecture",
" (proved by Perel... | [
"The ",
"wave equation",
" which is used to model (among other things) the propagation of sound waves behaves differently in odd and even numbers of dimensions. ",
"In odd numbered dimensions (except 1d) the wave propagates radially from a point source with a sharp wave front only supported at one point. If t... | [
"In physics, ",
"stable orbits",
" between two bodies can only exist in three dimensions (where the force of gravity is proportional to the inverse of the square of distance).",
" ",
"In graph theory, graphs embedded into the (Euclidean) plane can always be properly colored by ",
"four colors",
". Graph... |
[
"If the farthest known object is observed as 13.1 billion light years away, how far is it really?"
] | [
false
] | since it is 13.1 billion light years ago as well. how far is it really? light took 13 billion years to get here, so 13.1 billion light years away 13 billion years ago. | [
"About 45 billion light years if the Hubble Expansion Constant has acted as currently predicted. Sorry I didn't throw that in my first answer."
] | [
"So if space wasn't expanding a stationary (with respect to us) object that emitted a photon 10ly ago which just reached us today would be 10ly away. Since space is expanding how far away an (stationary before metric expansion) object is when a photon that it emitted reaches us after a certain amount of time depen... | [
"understood, but how far away is the farthest object, if it appears 13.1 billion light years away?"
] |
[
"What is the covid19 mortality rate among healthcare workers?"
] | [
false
] | Hi redditors. Do any of you know of any official data on covid19 mortality rate of healthcare workers (by country, preferably)? I would be very interrested to learn more about this. | [
"I don’t know where the official data is, but it seems like mortality rate may be higher than the general public.",
"This may be due to health care workers being exposed to higher amounts of virus. The more virus you start with, the further the infection has progressed before your immune system starts to work.",
... | [
"Thanks for the ref. Interresting that it seems like it's theoretically plausible at least, that virus load might increase mortality among healthcare workers, although some early data I have seen from wuhan seem to indicate a mortality rate equal to the healthy population"
] | [
"I cant see any reason why it would be any different than the same age and health groups in other professions. Infection rates will likely be different, (balancing much higher exposure with higher ppe use) but mortality rates are calculated off the underlying infextions rate, so there is no reason they would vary ... |
[
"Is there any scientific truth to the idea that you shouldn't sit too close to the TV?"
] | [
false
] | [deleted] | [
"No. However focusing on one spot for a long period of time can cause eyestrain, however that is only temporary.",
"You may find this interesting.\n",
"http://tlc.howstuffworks.com/family/tv-bad-for-eyes.htm"
] | [
"Yes, and modern flat screen LCD and plasma TVs are much more dangerous that older ones.",
"Their higher centre of gravity and narrower base means that they can, ",
"and sometimes do",
", fall on children sitting too close."
] | [
"Color CRTs put out EM radiation in the form of X-rays, from the electron beam slamming into the metal shadow mask. See ",
"Bremsstrahlung",
"."
] |
[
"What are the conditions for annihilation?"
] | [
false
] | Sadly I don't have a physics tutor to ask questions to, my understandings comes solely from self-study, so I apologise if my assumptions are incorrect or if the question seems outright stupid. I used to believe that most every-day interactions were physical. That is to say that if I push a chair, the atoms in my hand w... | [
"What interaction between a positron and electron is necessary for annihilation to occur?",
"Electron-positron annihilation is electromagnetic.",
"These particles are tiny and have opposite charge, so surely it's unlikely for them to actually experience contact so quickly?",
"They don’t have well-defined posi... | [
"Are you saying that it's caused by an electric force then?",
"The electromagnetic force, yes.",
"Is there a specific magnitude of force that must be experienced between them then? If so, what determines this value?",
"There's no threshold energy for electron-positron annihilation to photons. It can happen if... | [
"Sadly I don't have a physics tutor to ask questions to, my understandings comes solely from self-study, so I apologise if my assumptions are incorrect or if the question seems outright stupid.",
"I used to believe that most every-day interactions were physical. That is to say that if I push a chair, the atoms in... |
[
"How long would it take to send an unmanned probe to Kepler-22b and for it to send observational data back."
] | [
false
] | and what kind message would you send. (in the assumption there may be intelligence life) | [
"Voyager has travelled ten billion miles in thirty years.",
"http://voyager.jpl.nasa.gov/",
"One light year is about six trillion miles, which means that for Voyager to travel one light year it would take it about twenty thousand years. Keppler 22 b is six hundred light years away, so a probe to go there would ... | [
"Well to be fair Voyager was designed to interact with the planets not fly out of the solar system. It is conceivable that we could alter the use of gravity assisted slingshots to increase its escape velocity. But regardless, the shortest amount of time it would take would be 1200 years(600 years at light speed and... | [
"Perhaps another offshoot of this question would be.. how far would a man made probe have to travel to get close enough to identify radio waves or other signs of intelligent life? Can we do that from Earth or would the evidence simply be to far to detect at measurable levels?"
] |
[
"Why Do We Have Different Blood Types?"
] | [
false
] | null | [
"Short answer: Mutations.",
"Long answer: We consider type A blood \"normal\". The gene that encodes the glycosyltransferase enzyme (the part that differs in blood types) for B blood has 4 point-mutations compared to A (that means somewhere along our history, a cell replicated the gene with 4 mistakes).",
"So, ... | [
"There's a theory that having a mix of blood types in a population helps with virus resistance.",
"When viruses kill a cell and burst out they often have small pieces of cell stuck to them. The viruses then go out and try to infect other people.",
"If you're blood type A and get a virus from someone with type B... | [
"Most mutations get corrected (and don't end up getting expressed or passed on at all), so having a significant mutation develop is somewhat rare.",
"In terms of dominance/advantage, only O is \"defective\" (and it is genetically recessive). A and B will both be expressed in people with both gene (they're functio... |
[
"Is `wave function collapse' time reversible?"
] | [
false
] | It seems like it is not, but this is very strange to me since all of the other laws of nature are manifestly invariant under time reversal. The same is also true for the evolution of a quantum mechanical system in the absence of any observer. And if wave function collapse is indeed time irreversible, wouldn't that im... | [
"How silly to think that the equations we use to describe the world might actually describe the world!"
] | [
"No, the wave function describing that system changes over time as described by its Hamiltonian and the Schrodinger equation which are time dependent. In general, the probability distribution for the outcome you observe could change if you measure it 5 minutes from now or 10 minutes from now."
] | [
"No one really knows the mechanism that causes a wave-function to collapse. What we know from decoherence is that a QM system coupled to a macroscopic system will eventually evolve in such a way that the \"total wave function of the system\" will have bumps with completely disjoint supports. But nothing can tell yo... |
[
"Why the sun’s gravity doesn’t attract the Earth toward the sun vertically?"
] | [
false
] | If I drop an apple in the Earth the apple goes directly toward the center of the Earth because of the gravity. Why the Earth doesn't fall directly toward the center of the sun but it orbits around the sun? | [
"Imagine that you throw the apple horizontally - it'll move around the Earth for a bit before hitting the ground, right? Then you throw it again, but faster, and the apple travels a much longer distance before hitting the Earth.",
"What would happen if you threw your apple so fast that by the time it falls, the E... | [
"If you throw an apple, it will go a ways before falling to the Earth. If you throw it hard enough, around 18,000 mph, it will orbit the Earth, or would if there wasn't any atmosphere. The Earth is moving at around 67,500 mph in its orbit around the Sun, so that's why it doesn't fall in."
] | [
"Because the earth is hurtling sideways at over 66,000mph. This is fast enough to make us miss the sun while at the same time falling toward it.",
"If there were no air, you would be able to throw an apple straight out at 17,650mph and it would be going sideways so fast that it would be far enough away by the tim... |
[
"Is there a known mechanism that gives rise to fundamental electric charge?"
] | [
false
] | null | [
"I'm not sure if this answers your question, but there is a important theorem in physics called Noether's theorem. ",
"Noether's theorem (kind of) states that any time the behavior of your system doesn't change ( ",
"), when you change something about your system, there is a corresponding function of the system... | [
"To be clear, electrons do not get charge from quarks."
] | [
"Electrons are not made of quarks, they are a fundamental point-like particle. Things which are made of quarks are called hadrons. An electron is not a hadron. A proton, on the other hand, is an example of a hadron. Protons are made of three quarks. Neutrons are also hadrons, but they do not have any charge because... |
[
"Why isn't Dark Matter attracted by Gravity to form more dense objects?"
] | [
false
] | null | [
"Dark matter ",
" attracted by gravity, like all matter is.",
"The reason dark matter doesn't form more dense objects is because dark matter doesn't interact (significantly, at least) with anything -- even other dark matter -- so there is nothing to slow it down and keep it near the center of a gravitational po... | [
"Dark matter is attracted by gravity, but it does not form dense objects because it passes right through itself and other matter (at least that is one of the simplest possible types of dark matter, there are other possibilities as well). Without some form of interaction, it will never \"clump\". Clumping requires t... | [
"It depends how you define \"dense objects\" and on what scale. Non-self-interacting dark matter forms \"dense objects\" in the same sense that our solar system is a \"dense object,\" but not in the same sense that planets or stars are dense objects (which is what the OP obviously means)."
] |
[
"Could subjects in a study being aware of the placebo effect lead to a potentially useful drug/treatment's being rendered ineffective?"
] | [
false
] | [deleted] | [
"A placebo is used as an experimental control, so it is intended to deal with a range of possible problems that might come up experimentally.",
"If the people getting the real drug show significantly fewer symptoms of depression than the ones on the placebo, then experiment would indicate that the drug is having ... | [
"Yes. The negative aspects of a placebo effect are known as the ",
"Nocebo",
" effect."
] | [
"Couldn’t that issue be avoided by ",
" the subjects that they are not getting the placebo? (even if they are)"
] |
[
"Would a nebula looks as pretty from the inside?"
] | [
false
] | [deleted] | [
"the colors are mostly false colors. Astronomers take a picture with one filter, say for UV light, and color that picture blue. Then they take another picture say for one specific visible frequency and color it green. Then another filter for IR, and color that red. They superimpose those pictures and get prettyness... | [
"While that is true for NASA's phots, have you seen long exposure shots by amateur astronomers? \nThey use normal digital cameras and get wonderful amounts of color. ",
"http://starizona.com/acb/ccd/introimagingama.aspx",
"But you're overall point is correct. Probably from inside, the nebula would look really w... | [
"I think it's hard to say, but I'm not an expert, maybe a real astrophysicist could help. ",
"Here's",
" an image of the eagle nebula the author claims is true color. ",
"Here's",
" a more standard three color composite on wiki. If you want, you could probably do some google or google image searches for \"t... |
[
"Can someone please explain dispersion to me? I don't understand the physics behind why light can be dispersed into ROYGBIV."
] | [
false
] | in particular, I don't see how this violates the wave rule that the velocity of a wave is only dependent on the medium it is in. | [
"Check out ",
"this",
". You're understanding me correctly, light's speed through a medium depends on both the medium ",
" the light's wavelength."
] | [
"I'm not sure what you're talking about in particular, so let's start with a bottom's up approach.",
"Light is an electromagnetic wave that propagates through space ",
" a medium. A single \"bit\" of light, we'll call a photon, has three properties: wavelength, frequency and speed. They're all interrelated. The... | [
"according to rule #1 velocity depends on the medium, meaning a whistle vs a shout will travel at the same velocity in air. Dispersion violates this rule because each color travels at a different velocity despite them being in the same medium. is this correct? would that also mean other sources of Em waves travel a... |
[
"Is there any functional difference at either the hardware or software level between selecting 'restart' to restart your computer, or pressing shut down, and turning it back on?"
] | [
false
] | null | [
"At the OS level, no. The operating system will completely shut itself down either way. Likewise, all the hardware in your system ",
" have its state cleared during the restart. A reset signal is sent by the motherboard to all of the components in the computer on the restart. However, everything inside the comput... | [
"The 2 replies before this are misleading/wrong regarding the power button.",
"The easy part is that clicking or using a mouse on the start bar will cause a \"clean\" shutdown, where windows will send a signal to all running programs that they have to close now or be killed. This gives them time to close any open... | [
"Because software is unreliable. There has to be a way to turn the power off for real if the OS is locked up or otherwise so unresponsive that it doesn't respond to a \"polite\" shutdown notification from the firmware. You could pull the plug, of course, but it's not always convenient."
] |
[
"Does the position of leaves affect the rate of transpiration?"
] | [
false
] | Like, for example, does the apical pair of leaves have a faster/slower rate of transpiration than the bottom pair of leaves and why? | [
"Yes and no. There are sun leaves, which are closer to the top of the tree, have thicker cuticles, are thick, and smaller. Shade leaves are typically found nearer to the bottom. Shade leaves are thinner, larger (more surface area to catch sun), and have more chlorophyll. Sun leaves (A) are ",
"more efficient",
... | [
"I'd also like to point out that the position of stomata matter as well, although to a much lesser degree because almost all plants have them usually on the bottom of the leaf. Stomata are holes used for gas echange in plants, although they have the unintentional consequence of water loss as water evaporates out of... | [
"In addition to change in position, leaves may also change shape. For example, Live Oak leaves will curl downward creating a \"moist\" micro climate around the stoma protecting them from wind and heat. "
] |
[
"Higgs and mass (hasn't been asked yet that I can tell)"
] | [
false
] | I've searched the archives and haven't seen this one come up yet, so I'll ask. If the Higgs is the conveyor of mass, presumably this means "inertial mass" and it has been asserted that inertial and gravitational mass are equivalent, then what's the relationship between Higgs and (quantum) gravity? It has also been st... | [
"what's the relationship between Higgs and (quantum) gravity?",
"We don't know. We don't yet have a working model of quantum gravity, because mixing quantum field theory with general relativity leads to contradictions. Many people more brilliant than I are working on such theories, but it's safe to say that we ... | [
"Just a side point. The Higgs only gives mass to elementary particles. The mass of the proton, or other baryons, largely comes from the energy of quarks and gluons, not the Higgs mechanism. "
] | [
"So they are intertwined... That's what I was wondering. No discussion I have read yet has talked about it in any way other than inertial. Wouldnt it be an even bigger discovery then, if finding it also found something about gravitons?",
"I mean, people talk about Higgs like it just adds some kind of viscosity t... |
[
"Questions about CME's"
] | [
false
] | Are Coronal Mass Ejections visible to humans from space in the light spectrum, and what would be the effects of being exposed to a CME in deep space? | [
"Coronal mass ejections are indeed visible in the optical spectrum, although they would be difficult to see unless you cover the main disk of the Sun with something, since the brightness of the Sun will overwhelm your vision.",
"It depends what you mean by \"exposed to\" a CME. They are associated with higher X-r... | [
"CME's can be seen from space soon after their ejection from the Sun, provided the solar disk itself is occluded and other direct sunlight reflections are blocked from view as well.",
"Once the CME reaches the vicinity of any reasonably distant observer, however, it would be far too diffuse to be visible. An obse... | [
"That was extremely short and to the point. Thanks! "
] |
[
"Can you see time dialation ?"
] | [
false
] | I am gonna use the movie interstellar to explain my question. Specifically the water planet scene. If you dont know this movie, they want to land on a planet, which orbits around a black hole. Due to the gravity of the black hole, the time on this planet is severly dialated and supposedly every 1 hour on this planet me... | [
"By time dilation, we ",
" that the light emitted by those on the water planet over 3 hours in their rest frame is received over 23 years by the spaceship in its rest frame. So the observer on the spaceshift sees them move in very slow motion. The images are also extremely redshifted and very difficult even to de... | [
"Yup, the time dilation in that film was silly, 7 years per hour or something like that? That would mean everything in the sky would have been ",
" (hours in a year) x 7 times brighter than normal.",
"EDIT: not 2000 hours, no idea why I wrote that! ( Thanks ",
"u/jareds",
" )"
] | [
"Would the people on the water planet see their astronaut friend and the stars (blue-shifted, I assume) whizzing around at high speed?"
] |
[
"Safe way to keep my goggles from fogging in lab?"
] | [
false
] | When I am in Biology lab my goggles fog up really fast and never let up. I tried taping a few small wads of paper towels on the inside thinking it would absorb the moisture, but that only yielded minimal results. I have Rain-X for my car, but question it's safety with it being in a closed system with my eyes. Is it sa... | [
"Use cat crap. Seriously google it. That's what they use for ski goggles."
] | [
"Yeah, my morning coffee made it even less pleasant though since I am in the lab at 8 AM."
] | [
"ಠ_ಠ",
"Maybe that is how my lab partner got pink eye."
] |
[
"Are humans \"hardwired\" to divide the world into \"my group\"/\"others\"?"
] | [
false
] | null | [
"Yes we are. Humans evolved in tribal groups that required competition. As civilization developed this innate competitiveness never really went away. This is why humans can get so worked up about things like sports that we will kill each other (look up the soccer war, this legit happened). We are always finding an ... | [
"Also try reading \"Us Against Them: How Tribalism Affects the Way We Think\" by Bruce Rozenblit. Again, there's a lot of overwhelming evidence of your question. That review and this book are just two examples I had fast access to but Google Scholar search anything about tribalism in humans and you'll get 100s of a... | [
"Human beings are naturally categorical. It's not so much \"us vs. them\" as it is \"known vs. unknown\".",
"If you have knever seen, heard of, or experienced a couch and walked into a living room one day, on of the first things you're going to do is asses this huge unknown item.",
"Is it a bomb? Can I eat it?"... |
[
"What is a mechanism of eyes getting tired by light?"
] | [
false
] | null | [
"Do you mean adaptation / afterimages? Or fatigue like you can get from staring at a computer screen for a long time?"
] | [
"There are several factors that could contribute including the drying out of your eyes by not blinking frequently enough or the fact that you are focusing constantly at the same point in space (the ciliary muscle which controls the shape of your lens gets strained). You can find more information just by googling ey... | [
"I mean fatigue cause by working in bright light in operation room as a surgeon or staring at computer screen for a long time."
] |
[
"I just watched a YouTube video where a phone battery exploded second after being stabbed with a knife. What exactly is happening to get that sort of reaction?"
] | [
false
] | [deleted] | [
"Many things happen at the same time. For instance, when you poke the battery with the knife, you create a short circuit (assuming the battery is charge). This will release a lot of heat, which will heat up the electrolyte in the battery. The electrolyte will become volatile and flames up if a spark is created. Thi... | [
"Lithium is an alkali metal, like sodium and potassium. Alkali metals are highly reactive and flammable and so don't in nature in their pure forms. ",
"These metals have only one electron in their outer shell, and readily lose that electron in ionic bonding with other elements. This is the reason for their reacti... | [
"Spot on. OP may be interested in ",
"this video",
" documenting the reactions of many alkali metals with water.",
"Don't try it, at home or otherwise."
] |
[
"Is there a kind of numbers more powerful than complex numbers or are those the most powerful among things that qualify as numbers?"
] | [
false
] | I'm afraid I have to explain where I'm coming from, exactly. We start with natural numbers: 0, 1, 2, 3, ... They obey several important rules regarding addition and multiplication: both are commutative, for starters: . Then we notice that the inverse of our addition operation sometimes is undefined, is not a natural nu... | [
"We need to talk a little about ",
"Fields",
". These are arithmetic objects where you can add, subtract, multiply and divide in a nice, commutative way. We can think of a \"Number System\" as being a field that we can construct in natural ways starting from the Natural Numbers. ",
"It's not hard to show that... | [
"There are other ways to construct fields that extend the Complex Number, but the Fundamental Theorem of Algebra says that it can't be finite dimensional and the fact that the Complex Numbers are complete says that it can't be geometric/topological in nature. For instance, I can look at the collection of all ration... | [
"If I have the rational numbers, and consider all the logarithms of rational numbers at every rational base, I have the set log_r(s) where r and s are positive rational numbers. I can look at the smallest field that contains all these elements and this field will have a ",
" basis over the rational numbers. This... |
[
"Fermi Paradox: How can a truly multi-stellar civilization die? (Looking for scientific perspectives or book recommendations.)"
] | [
false
] | null | [
"Astronomy"
] | [
"Hello,",
"Open-ended questions like this would be more appropriate for ",
"/r/AskScienceDiscussion",
". You might also be interested in ",
"/r/AskScienceFiction",
"."
] | [
"Maybe I shouldn't have classified it as astronomy. It's really a population dynamics question, but in the context of a galactic ecosystem. I want to know whether a causally disconnected expanding sphere of colonization can be universally disrupted by purely local influences"
] |
[
"Can you get all of the energy out of a battery at once?"
] | [
false
] | Say you needed all of the electricity out of a battery in a very short amount of time, can that be achieved? | [
"No, there is a physical limit to how fast you can extract power from a battery. Here is a case example: take a lithium ion battery. How does the energy get stored in this case? You are storing charge, which can become mobile on-demand and then be a current that does work. In a Li-ion battery lithium ions (surprise... | [
"I would argue that short circuiting the battery would get all the energy out of the battery faster than a capacitor. Place a wire with the least resistance across the terminals. (Obviously don't do this, as it may cause a fire or until the wire across the terminals melts.)",
"A capacitor based discharge would s... | [
"In the case of short circuiting, where does the energy go? Into the wire and than lost as heat?"
] |
[
"What (if any) physiological changes do men experience when their partner is pregnant?"
] | [
false
] | As a follow up, what drives these changes? Pheromones released by the woman? Just seeing a pregnant belly? The conscious brain trying to process and prepare for the future? | [
" Make sure you distinguish between research on father's-to-be vs. fathers. The findings are better understood for fathers, whereas there is far more dispute regarding changes in expecting fathers."
] | [
"There are cases, I think just slightly over 10%, where men have been known to experience increases in ",
" depression, often linked to increases in stress and cortisol. It hasn't been sorted out if that's because of having to live with stresses of pregnancy, or actual hormonal responses to being around a pregnan... | [
"I know that the question was specifically asking about what happens when their partner becomes preganant, but I thought it was worth drawing your attention to ",
"this",
" article about what happens when to the fathers brain shortly after he becomes a dad. ",
"Shortly after a monkey becomes a father there is... |
[
"Why is cancer so prevalent, considering the complex factors needed to initiate such growth?"
] | [
false
] | (Disclaimer: I hope I'm not simply showing my ignorance here by asking this question and that it's worthy of being asked) After reading , and taking note of its laundry list of needs for cancerous growth: Circumvent DNA Repair Overcome Apoptosis Recruit blood vessels to supply nutrients Make growth signals/ignore inhib... | [
"It's probability. If you live long enough you WILL get cancer. It is inevitable. ",
"Consider this: the error rate of DNA polymerase is approximate 1/10",
" which means in the course of copying the 3 billion base pair genome, every time, you can expect it to make 300 errors each time. Wow. Considering your b... | [
"Actually it is a miracle that it doesn't happen more often, given:"
] | [
"This is not true of all cancers. The classic example is testicular cancer, which has a peak incidence at about 30 years of age and declines. You are less likely to get testicular cancer at 40 than 30 and less likely to get it at 50 than 40.",
"Certainly that is true of certain kinds of cancer, but for the majori... |
[
"I can type without looking at the keyboard, but when asked to draw a keyboard, I am completely unable to correctly label half of the letter keys. How is this possible?"
] | [
false
] | null | [
"Exactly, just try it yourself. I get this more often with video games- if someone asks me what button to press to do something, I have to pick up a controller to figure out what to tell them."
] | [
"Can't you just pretend to type a word and figure out where the letters are? I know where the letters are in reference to my fingers. So \"i\" is right middle finger up. I could easily use that to draw a keyboard. It is much easier to pretend to write out a word while paying attention to where the fingers want to g... | [
"So if someone wanted to draw a keyboard, they would have to pretend to type and draw each letter key they tried using?"
] |
[
"If supposedly solid objects are mostly empty space, why does it seem that no light penetrates solid objects?"
] | [
false
] | If I hold a laser pointer up to a thin piece of solid plastic, then with my naked eye I can't see any "laser light" coming out the backside. Since supposedly solid objects are mostly empty space why is it that (it seems) absolutely zero light penetrates solid objects? | [
"Not all solid objects are opaque. Opacity is a bulk material property that depends on ",
" the material, and the color of light you shine through it. A color filter is a great example of a solid that will be clear to only some colors of light, while blocking others. You can have something like carbon, which i... | [
"The \"empty space\" are the electron clouds within the atoms. Since the hard-shell size of the electron is very small, it is often awkwardly stated that an atom is mostly empty space. But \"size\" is really dependent on how fast an object is travelling. Edit: \"fast\" in a classical sense. In other words, how much... | [
"Thanks for the well-drafted response. I think it all makes sense--the asteroid analogy really helps to visualize things."
] |
[
"Has the weight or mass of Earth changed overtime?"
] | [
false
] | For example if everything were even, all the resources on Earth have always been here and the contributed to the weight or mass of earth. We take those resources and make things. Sometimes the things we make emit gases or substances that upon leaving the atmosphere don’t weigh on the Earth anymore. Then all the space ... | [
"Y'all are weird for talking about the mass of rockets. They weigh very little compared to 40 kilotons of dust falling into the atmosphere every year, and that is eclipsed by 100kt of hydrogen that bounces out of the atmosphere annually. ",
"BBC News - Who, What, Why: Is the Earth getting lighter?\n",
"http://w... | [
"“Population growth and new buildings are not a factor, he says, because both of these are actually made up of existing matter on the planet.” ",
"Woah. So earth’s 7 billion people didn’t actually add anything new in terms of total matter? For some reason I can’t get my head around the idea that all the way from ... | [
"Also, the sun shines on Earth and photosynthesis occurs making green leaves that then falls to earth and makes soil. So that technically adds mass.",
"I'm not sure just how tongue-in-cheek that last bit was. But for the record, while the sun emits various types of radiation, photons are massless."
] |
[
"If you sleep in a colder environment, will you burn more calories?"
] | [
false
] | If you sleep at a lower temperature will your body burn more calories to keep you heated? Is it a negligible amount? Does anyone know what would be the peak temperature for this (at some point your body must be heating at 100% capacity I imagine and lowering the temperature anymore wouldn't help). Just a curious though... | [
"Yes, your body works very hard to maintain your body temperature in a narrow range, and any time spent in cold weather will mean more energy spent to stay warm. I don't have specific numbers for you, but someone can probably give you a back-of-the-envelope calculation.",
"The problem with this strategy is that ... | [
"Wouldn't running or exercising create considerable heat to keep you warm?",
"EDIT: can someone tell me why i'm being downvoted?"
] | [
"You're probably being downvoted because someone else wanted their comment higher."
] |
[
"What new subreddits would you like to see?"
] | [
false
] | null | [
"Haha, it happens. Have a good one!"
] | [
"First off, your post is not appropriate for AskScience, this is an AskReddit question. Secondly, your suggestion of ",
"r/askmedicine",
" can't exist as that would violate Reddit's terms of service. Not to mention that those of us who are physicians would be legally liable for any answers we give and could be... | [
"Holy crap. I could have sworn I submitted this to askreddit. "
] |
[
"How are the cells in a fern gametophyte able to reproduce and grow with only one set of chromosomes?"
] | [
false
] | null | [
"They multiply by mitosis like cells with two sets of chromosomes, they simply couldn't undergo meiosi because they can't reduce their chromosomes. ",
"Having one set of chromosomes doesn't affect meiosis, it just makes organisms more likely to suffer from mutations, since, if there's a mutation in a gene that is... | [
"I see. So if they differentiate tissues, they do it by just reading the one set of genes they have rather than the to sets we have?"
] | [
"Yeah, I don't have a lot of knowledge on gene regulation and expression but they'd have to be able to differentiate and grow normally with just one copy."
] |
[
"What's under the Canadian Shield? [geology]"
] | [
false
] | I know the Canadian shield is a rich source of minerals but for the life of me can't find any information as to what the layers underneath the Canadian Shield are. | [
"The shield isn't just one rock type. It consists of multiple volcanic arcs, ophiolites, and even sedimentary rocks that have been smashed together over millions of years. So generally when talking about the shield it would be correct to say the mantle is underneath it. Also, the mantle is very much solid - not ... | [
"We have samples of the mantle brought up through tectonic and volcanic activity. We haven't yet managed to drill down and directly sample the mantle."
] | [
"As I understand it, once you got through the craton you would be encountering the upper mantle."
] |
[
"Is there a limit to how many people can view an object?"
] | [
false
] | [deleted] | [
"If you've ever seen a group of people crowded around an object, but you were unable to see the object yourself because they were in the way, you have experienced this phenomenon. So yes, the limit is based on the distance from the object to the inner layer of the crowd, and the packing density of the people. Very ... | [
"Well yes, at the maximum limit (which would increase with r ) the photons would be blocked. The same way you turn a light on in a room with no windows, and close the door. No one outside can observe the light as its being blocked by the wall. Then imagine that the walls/floor/ceiling are people, and the atoms that... | [
"Would not very small equilateral triangular people get more people into the same 'area' - since a hexagon is just 6 equilateral triangles"
] |
[
"Can you have a reference frame moving at the speed of light?"
] | [
false
] | Is a reference frame traveling at c valid (say a reference frame centered around a photon)? I understand that any (almost any?) inertial reference frame is valid; however, does this break down as velocity approaches the speed of light? Can you use a Lorentz Transformation to convert to a photon's reference frame and st... | [
"Yes and no. There are situations in which it's useful to boost a system to infinite momentum in order to reduce the number of degrees of freedom, and the corresponding mathematical complexity of the problem. But that's a mathematical trick, not a valid description of a real phenomenon. And it only works if you col... | [
"No.",
"I mean, you can take the limit as the relative velocity approaches c, and you get ",
" answer. The problem is that you get something meaningless; all spacetime intervals in the reference frame have zero length. What are you going to do with that?"
] | [
"Write a science fiction novel, of course. Or maybe a quantum self-help mysticism manual."
] |
[
"Was there life on Earth when the asteroid hit that tore off our moon?"
] | [
false
] | If so, are there potentially fossils on the moon, or are elements of the fossilization process not present over there? | [
"As far as we know, no. The moon was formed roughly ",
"4.5 billion years",
" ago, and our oldest records of life date back roughly ",
"3.6 billion years",
". The earth was most likely a dead planet when it was struck."
] | [
"Thank you. "
] | [
"The Earth would have been a mostly-molten ball of rock without any stable atmosphere and certainly without any liquid water. And just to clarify for OP, it was a roughly Mars-sized body (referred to as Theia) which would have hit the Earth, not just any old asteroid."
] |
[
"After inserting a donor, how do surgeons \"restart\" a heart after a transplant?"
] | [
false
] | null | [
"Yes, most eletrical pulses are created in the brain, which controls the whole body. The heart is the only organ that is autonomous in eletrical pulse, it controls itself. Fun fact: A heart can still beat seconds, or even minutes outside the body before stopping because of oxygen starvation! Usually a simple massag... | [
"You forgot about the enteric nervous system, which is completely independent from the brain as well. "
] | [
"That is incredibly interesting. I never knew we had cells that just create electricity"
] |
[
"How does the Hubble Telescope take pictures?"
] | [
false
] | I know in photography to take pictures you need to be standing still to not blur the image, you also need to (depending on your exposure and a bunch of other factors) also keep it still for that factor. So how does it take clear photos? | [
"The HST is an active tracking telescope. It maintains a specific orientation relative to the stars when it takes an exposure. It does this by using sensors to lock onto \"guide stars\" and then using its attitude adjustment systems (reaction wheels) to keep those guide stars on the same position on the sensor (cov... | [
"[ENCRYPTED]\nU2FsdGVkX1/47spXJ5vdqqPTLu//0X7vPmHW0KN0hNuxBcv9LCstScsbLGU0th6IvfAPWycX/3JgJjdmmx6fxE7/4C1ApnBNmWYInldWQAts0yrVcg55jVOcI9xWkMStkOH60WQfa0Oh5I74XQAmNVjMb8cug2t/r9/gdjKdBonFkmbuheAks/u5Y2/e+xeHltioBwJ0RSKvluSenuB0fuW5Ijn4seMQTNDMG17KbRYmCJpr316DFA0ZPJzVcDly0+E5UN+SfXSPwB5r1kipoougZm/mzI1P/Z9Uq9VVk+5/im... | [
"Hubble orbits the Earth at about 7 km/s. The Earth orbits the Sun at about 30 km/s. How can we get clear pictures from the Earth?",
"The answer is the same in both cases, the objects pictured (or the resolution of the telescopes) are so large that the motion of the telescope is negligible."
] |
[
"Could satellite take picture of street as if you were to take it standing in middle of street by looking at side of planet?"
] | [
false
] | null | [
"To add to this, the optical issues of reaching through that much more atmosphere would not be insignificant.",
"And perhaps most of all - a lot of what is thought of as satellite imagery by the general public (google maps for example) is actually aerial photography."
] | [
"Yes, that's technically possible. A view angle that's near-tangential can allow for views that might seem more natural for humans. But it's not particularly practical -- much of the value of satellite imagery is being able to avoid obstructions.",
"Getting the satellite to just skim the earth's surface would als... | [
"Sorry, let me clarify. All of the global and regional imagery is satellite. once you're down at the level of seeing individual buildings it is mostly now aerial photography. Very remote areas are still satellite but with a corresponding loss of fine detail"
] |
[
"What would be observed in the Large Hadron Collider to indicate that a new particle might exist, for example, a supersymmetric particle counterpart?"
] | [
false
] | null | [
"It depends on the specific particle and analysis."
] | [
"At the relevant energies the effective collisions are between partons, i.e. quarks or gluons. The rest of the protons doesn't participate in the main collision. They just make things messy afterwards (hadronization).",
"It would be difficult to tell if a new particle is fundamental, but the study would depend on... | [
"If the supersymmetric particles form composite particles like, for example a proton is formed from quarks, the structure of which was probed by deep inelastic scattering experiments, would LHC be able to detect the signatures of this, because the LHC uses comparatively large particles such as protons and not small... |
[
"Do bland-tasting strawberries have less nutritional value?"
] | [
false
] | Wild strawberries and home-grown strawberries usually have a ton of flavor, while store-bought strawberries taste like water -- is there a nutritional difference between them? Are there more vitamins in the more flavorful ones, or just more sugar? | [
"Kind of a strange one here, the background will depend upon your region to a degree.",
"Strawberries have, for a long time in some circles, been regarded as ",
"non-climacteric",
":",
"because its ripening process is not governed by ethylene.",
"Fruits like tomato are typically harvested when they are ve... | [
"The effects of ethylene are myriad, ",
"climacteric ripening is extremely complex",
". Evolution of ethylene ",
" is emulated by creating high external concentrations of ethylene gas, it is proposed that the mechanism for climacteric ripening results from gene regulation which occurs in the presence of the e... | [
"Correct, although flavor will be subjective, the ethylene actually has the effect of making many fruits, like tomato and banana, sweeter as they ripen. This is because part of the change which occurs is that the ethylene regulates gene expression which causes stored starches (stable, long lasting, less quickly dig... |
[
"How do we remember and mentally reconstruct tastes and smells?"
] | [
false
] | I was typing up a cookbook entry about cumin and it mentioned mixing cumin, cinnamon, and saffron. Instantly I knew exactly what all three taste like and what they'd taste like together. Visual information retention I can understand, as that image is crafted by the brain from light received by your eyes. It never reall... | [
"the brain retrieves the stored information of that taste in a relatively same manner as when you retrieve visual memory.",
"Definitely need to see a source for that."
] | [
"the brain retrieves the stored information of that taste in a relatively same manner as when you retrieve visual memory.",
"Definitely need to see a source for that."
] | [
"Right, so you're thinking about this all wrong.\nLight is emitted by something. Light hits retina. And activates certain retinal cells. Activated Retinal cells sends signal into the brain. The spatial pattern of cells activated in the retina activates a certain collection of neurons in the brain. Is is this patter... |
[
"Why does the Earth's gravity (or gravity in general, for that matter) pull with a constant acceleration rather than a constant force?"
] | [
false
] | I'm in Physics II, so I know of Newton's Law of Universal Gravitation, F=(mgG)/r , so I know that the force between two masses only depends on the distance between them, but ? Do we know why? Why is it that a 10kg object will be pulled with a force of 98N while a 1 kg object will be 9.8N, yet are accelerating at 9.8m/s... | [
"Why does the Earth's gravity (or gravity in general, for that matter) pull with a constant acceleration rather than a constant force?",
"Okay basically it works like this: the ",
" of gravity is stronger for heavier objects, proportionally to their masses.",
"But in accordance with the idea of ",
", heavi... | [
"Each kilogram of mass experiences the same pull. So a 1kilo mass experiences ",
" the pull of a 2kilo mass. Why then does it not go at half the speed it has half the pull?",
"Because it also has half the mass. Imagine two bowling balls - one 1kg and the other 2kg. Which is harder to push along the floor? The h... | [
"Let's start with the last question: The force is proprtional to the mass of the object being pulled (so double the mass means double the force.) When you think about it, it has to be this way:",
"Imagine if the force was constant, say 98N, regardless of mass. An object of 10kg would be pulled by 98N. But split t... |
[
"Does the temperature of the water in a glass of ice water change as the ice melts?"
] | [
false
] | null | [
"When pure ice reaches 0 degs C it starts to turn into water. The water/ice mixture will stay at 0 degs C until all the ice is turned into water. Then the water will rise above 0. The same is also true for reverse. Also this is the ideal case. Statistically speaking there is always the probability for fluctuations... | [
"When ice melts the temperature does not change. The energy goes in to the melting process rather than increasing the temperature."
] | [
"While the other comments are true, a better answer would be that the nearby water remains at a nearly constant temperature while the water, say, at the bottom of the glass warms up and rises to the top, causing a convective current to form within the glass"
] |
[
"Why does high blood sugar damage the kidney's filters?"
] | [
false
] | [deleted] | [
"I'm trying to work out how diabetes can cause diabetic nephropathy.",
"This is a complex topic and the exact mechanisms are unknown. Here are some of the contributing factors: ",
"Glomerular hyperfiltration - filtering more glucose, fats, and proteins leads to inflammatory reactions and fibrosis (controversial... | [
"I work in dialysis and have taken anat & phys, emt paramedic classes and I was under the impression that high blood sugars cause damage to capillaries such as those in the kidneys, eyes, toes and fingers. Please correct me if I'm wrong or if my assumption is too general. Didn't get to read the sources but will as ... | [
"Diabetes can manifest with a variety of vascular complications. In general you can look at these in two categories: ",
"Microvascular, includes: retinopathy (eye problems), neuropathy (nerve problems), ulceration, and nephropathy (kidney problems) ",
"Macrovascular, includes: heart attack, claudication (pain ... |
[
"Is it safe to watch the sun with the naked eye during a sunrise or a sunset?"
] | [
false
] | Why? | [
"It is safe to watch because of an effect known as Rayleigh scattering. When the sun is at a greater angle, it has to travel through more of the atmosphere to reach us, meaning the higher frequency light has a higher chance of \"bouncing\" off of the gas particles in the atmosphere. This is also why the sun changes... | [
"The amount of dimming and colour changing depends on atmospheric conditions. On a humid summer day sunset, the sun turns totally red, and it might even fade out a bit above the horizon. On a clear cold day, the sun might have colour between yellow and orange and feel too bright too look at. I have difficulty belie... | [
"the sunlight during sunrise and sunset is much more attenuated (dispersed) due to scattering attributed to the long passage the sunlight takes through the atmosphere when it is just over the horizon. "
] |
[
"Do pronghorns have velvet?"
] | [
false
] | have what's basically a hybrid between ) and ; permanent bone cores that grow and shed a layer yearly. , does anyone on here know whether they have - blood vessel-rich skin that supplies nutrients to growing antlers? | [
"When I think of velvet, I think of a thin layer of haired skin-type tissue, vascular like you said, that antlered ruminants eventually rub off to reveal the underlying bony antler that persists for several months until it too falls off. ",
"North American antelope don't have that. It's more like a thicker layer... | [
"North America antelope are one of a kind, yes :)"
] | [
"No problem. The other thing I thought to mention - antelope horn shedding is a bit like how you lose a fingernail after hitting it with a hammer. Sometimes it hangs on for months until the new fingernail pushes underneath of it, causing it to fall off."
] |
[
"Why can't I cut a solid, and then stick the two pieces back together again?"
] | [
false
] | If I take a solid iron rod, and saw it in half, what is actually happening on an atomic level? And why I can't I stick the two solid pieces back together, unless I convert one of the pieces to liquid first? | [
"You can. In fact, it's known as cold welding and commonly used in space. ",
"Under normal conditions, the moment you cut it, contaminants stick to the surface and the metal reacts with the atmosphere to form an oxide layer. This prevents the previous metallic bonds from reforming. ",
"For other objects, they t... | [
"Why don't two piece of glass stick together?",
"The surface of glass is very \"bumpy\" on an atomic level. The pieces \"touch\" each other only on a very small area. They do \"stick\" together there, but the force holding them is too small to carry their weight.",
"You can do 2 things to make 2 pieces of glass... | [
"Why don't two piece of glass stick together?"
] |
[
"Did the sun's recent explosion cause the sun to move even a hair?"
] | [
false
] | Theoretically it should have right? Action-reaction and with no other forces on it (gravity)? Since action-reaction forces are ideal in space does that mean the sun moved just a hair? What could this mean for the future? | [
"The sun is moving through the solar system all the time, mostly around the center of mass of the Jupiter's orbit with some perturbations from Saturn and the other planets. Momentum would be conserved when the sun burped out its gas, but that wouldn't have much effect on its path."
] | [
"thanks for your reply!"
] | [
"Solar ejections are equally likely to occur in any direction.",
"Over the course of time, this tends to average out. The movement by a hair in on direction will be offset if the next explosion is from the other direction.",
"EDIT: By any direction, I mean any radial direction. They are more likely to be ejec... |
[
"Is water necessary for tectonic activity to take place? if so, why?"
] | [
false
] | So i seen this mentioned on a youtube video about Venus. It mentioned that Venus has no tectonic activity because its water evaporated millions of years ago. What effect does water have on tectonic activity? | [
"The surface temperature is extremely high on Venus, which is a big reason why the average surface temperature there is 460 Celsius, where it is about 14 Celsius here on Earth. Sure there is still convection still going on Venus, however the difference in Surface temperature and Core temperature is not far enough ... | [
"No it is not needed, you need convection from the core outwards to drive tectonic activity. What cools it on the surface doesn't matter as long as the surface is cooler than the core so that convection will continue to occur."
] | [
"Is the problem with Venus that there is no significant cooling on the surface for convection to take place?\nSide question: does Venus have any levels of convection taking place?",
"Thank you for your answer"
] |
[
"Why do some forms of birth control (pills specifically) limit their starting dates?"
] | [
false
] | null | [
"Most hormone pills have a biphasic or triphasic combo of progesterone and estrogen. This is done to mimic\n the natural hormones of the body but ultimately the levels of the estrogen and progesterone are titrated to a level that mimics pregnancy and prevents ovulation and also thickens cervical mucus to prevent sp... | [
"The pill essentially stops the egg from being released. If you take the pill too late you will already be ovulating and be able to get pregnant. Each pill is different and has different hormones. It isn't \"unsafe\" but it ensures your taking the hormones during the correct times. Side note it is best to wait a mo... | [
"The reason isn't one to worry about so much for most basic estradiol contraceptives. The reason you're told to do that, is because if you start then, you will be protected from pregnancy by the time your menstruation ends. Because, generally oral contraceptives like this and ortho take a week to properly give you ... |
[
"At what altitude does the sky cease to be blue?"
] | [
false
] | Is it always blue until you leave the atmosphere? | [
"I will answer your question with a question.",
"At what point does the red become blue in the following image?",
"http://d2o0t5hpnwv4c1.cloudfront.net/612_gradients/webkit.jpg"
] | [
"Sorry, I guess the point I was trying to make was that as you move outwards from the atmosphere, the blue will eventually become darker and darker, until it is totally black. You could arbitrarily pick a point where you say \"There, it's black now, not blue\" - but it would probably be different for each person.",... | [
"Sky gets dark at around 30 kilometers. You can see stars during the day at these heights."
] |
[
"I can throw a baseball a lot further than a ping pong ball. I cannot throw a bowling ball nearly as far as a baseball. Is there an \"optimal\" mass or mass to diameter ratio for a ball to throw it as far as possible?"
] | [
false
] | I'm assuming a perfect sphere here, so you can ignore modifiers like dimples on a golf ball. | [
"There are a lot of details which this answer will not contain, but this will give you the tools to start thinking about the question. ",
"The reason you can't throw a ping pong ball very far is that it is that the force of the air resistance causes a large acceleration on the object. The force on the object due ... | [
"So something extremely dense and aerodynamic but not very big would be best, right?"
] | [
"well when you throw a ping pong ball it has very little momentum compared to a baseball. momentum is p=mv so if you throw the balls at the same velocity then momentum=mass. Less mass = less momentum so it wont go as far. As for the bowling ball its just so heavy that you have a hard time getting it to the velocity... |
[
"Is the temperature of a black hole absolute zero?"
] | [
false
] | Since matter keeps getting denser and denser, and moves less and less to the point of absolute zero where nothing is moving or vibrating, and it is giving off no black body radiation, would a black hole be absolute zero? It fits the characteristics of what something would be like at absolute zero. | [
"This was thought to be the case before the 1970s, but Bekenstein and Hawking showed that black holes actually emit blackbody radiation, albeit at a very low temperature for realistic-sized black holes. The temperature is inverse proportional to the mass, and for a solar mass black hole, the temperature is about 60... | [
"It happens due to quantum effects on the even horizon. If a black hole cannot \"eat\" anything, then eventually it shrinks and \"dies.\" Of course it's not like its shooting out stuff at a huge rate, it's very little matter that escapes for every unit of time."
] | [
"Yes, a solar mass black hole is definitely still way colder than the CMB. But if you had a small enough black hole, the temperature could get quite hot. Hawking has been hoping for a while that evidence for small black holes (perhaps created in the early universe) could be detected, which would be the best hope fo... |
[
"[physics] Why doesn't Helium freeze at 0K?"
] | [
false
] | I know reaching 0k is actually impossible. But from my understanding, all predictions indicate that helium would remain a liquid at 0k | [
"The interactions among Helium atoms are too weak, at atmospheric pressure, to condense Helium to a solid even at absolute zero. Note that, at absolute zero, the atoms still possess a positive amount of kinetic energy. (I.e. they do not slow down to zero speed at zero Kelvin.) An increase in pressure is required to... | [
"At 0K, atoms have the minimum amount of kinetic energy. If the potential energy of a flat sheet of atoms looked like an egg carton - a lattice or grid of wells - then imagine each atom is wobbling back and forth inside the well. However, because of \"quantum\", the lowest possible energy state of each well, or sim... | [
"I thought the definition of temperature was based on kinetic energy. How do atoms retain kinetic energy at a theoretically perfect and absolute 0K?"
] |
[
"Why does old coffee stick only to the highest level in a cup?"
] | [
false
] | I've noticed that whenever a cup of coffee or hot chocolate is left out and cools, it always leaves behind a ring where the highest level was. Why does this happen to drinks and soups when hot but not when cold? | [
"Good question! The physics of coffee rings is pretty interesting and was worked out in the 90's - see ",
"this paper in Nature",
", and if you don't have access you can find a non-paywalled copy ",
"here",
". Coffee is a colloidal suspension of solid particles in a liquid. At the \"corners\" of the liquid ... | [
"Why do anything? "
] | [
"Why do anything? "
] |
[
"What is the (engineerical) knowledge concerning the longevity of Batteries in relation to their performance?"
] | [
false
] | For example a lithium ion battery (48v / 29 Ah). Does the performance of either 1 kwh, 2 kwh or 3 kwh influence the longevity, if so in which way? | [
"It's not entirely clear what you're asking here. Please correct me if I'm wrong, but what I think you're asking is: do we know how long batteries last (either runtime or lifetime) given a certain power usage?",
"If that's the case, we do. Check the data sheet for your favorite battery. You'll notice the nominal ... | [
"Ah, I see now! I wish I could give you a better answer right now; all I can say is your general suspicion of the battery exhibiting lower longevity is what I have experienced in my projects. I will allow others to share whether there has been any extensive testing done on this. Great topic and I don't think I've s... | [
"Hi there,\nFirst: Thank you for your reply. Second: Please bear with me as english is not my first language. I am interested in the experience through testing results by engineers versus the theoretical supposed outcome. For example when named batteries are build in devices/or vehicles. Further example: let´s say... |
[
"Space Telescopes: Since they are _somehow_ moving, relative to the Earth or Sun (which are both moving), what is the longest exposure time they can use without getting motion blur? How does this affect clarity and detection?"
] | [
false
] | Since the observer is moving, a long exposure time will produce motion blur of the target, but long exposures also allow for increased sensitivity to weak light. I'm curious how space telescopes are hypothetically limited since they are always in motion (not to mention their targets). | [
"You can read about the Hubble's pointing systems ",
"here",
".",
"The simplest mechanism is the use of gyroscopes: these keep the Hubble pointed in the same direction in space even as it orbits the Earth, so you don't get immediate blurring. The Hubble ",
"ultra deep field",
" image was made with numero... | [
"a long exposure time will produce motion blur of the target",
"Not really no. Telescopes in space and on the ground have autoguiders called fine guidance sensors on space missions which track objects in the field of view. They sense tiny errors in the pointing of the telescope and actively correct for this by fe... | [
"Cool. ",
"Do you know if 20 minutes is the maximum time for an exposure? Or what kind of distortion we get with a 20 minute exposure (minimal, but certainly not zero...)?"
] |
[
"What is the most humane method of execution?"
] | [
false
] | By humane, I mean which method involves the least amount of suffering for the person who is being executed. Conforming with this definition, which method is most humane? The gulliotine, hanging, the electric chair, lethal injection or something else I have not listed here? Also, if the most humane method is not the one... | [
"In 2005, University of Miami researchers, in cooperation with an attorney representing death row inmates, published a research letter in the medical journal The Lancet. The article presented protocol information from Texas and Virginia which showed that executioners had no anesthesia training, drugs were administe... | [
"There was a good ",
"BBC Horizons",
" episode about \"humane killing\", from what I remember of it, they ended up advocating death by hypoxia caused by a noble gas as being the best method. See the ",
"wikipedia article"
] | [
"Wow, your argument didn't seem that hard pressed... I stand corrected! I had no idea the injections weren't administered by a physician; I made a poor assumption. That's too bad as if administered correctly lethal injection should be painless. Thanks for posting this!"
] |
[
"What does computer data look like physically? What makes certain hard drives hold more data than others?"
] | [
false
] | Thanks for all the responses everybody! | [
"This kind of breaks it down",
"guy's brilliant"
] | [
"There's various different forms of computer data.",
"In RAM, and while the CPU is working on it, it's simply electricity; often +3.3 volts of electricity means \"1\", while 0 volts means \"0\". All data is made out of 1s and 0s stringed together; for example, the letter A can be represented as 01000001.",
"On ... | [
"Every electron in a metal has a spin and as a result acts like a tiny tiny magnet. Now normally all these magnets are oriented randomly, so the effects of one are canceled by another. But in certain materials, quantum mechanics (many hairy details that you probably don't want to know) results in neighboring spin... |
[
"Can the body use alcohol as fuel?"
] | [
false
] | You often hear that alcohol is fattening or contains a lot of calories. It's said that alcohol contains 7 calories per gram. But can ethanol itself be used by the body as a fuel source? By what mechanism? Does it ever get converted into glucose that the brain and muscles can use? Does it get converted into fat and stor... | [
"The article ",
"Relationships Between Nutrition, Alcohol Use, and Liver Disease",
" has some information about this:",
"\"",
"\"",
"The article ",
"Alcohol and Nutrition",
" observes that:",
"\"",
"\"",
"Back to your questions:",
"Assuming that you got vitamins and minerals from supplements a... | [
"Yes ethanol does contain ~7kcal/gram. Ethanol itself isn't a fuel source, but is converted into \"fuel\". ",
"Ethanol is detoxified in the liver by this process:",
"\nEthanol -> Ethanal (",
") -> Ethanoic acid (",
")",
"Acetic acid can be converted into ",
" which is used in ",
". ",
"Ethanol ... | [
"That's very interesting. Thanks."
] |
[
"How is surface tension related to droplet formation?"
] | [
false
] | Say you're trying to form a drop of water by letting it out of a small tube. Using the same tube, after adding soap to the water, will the drops formed in this process be bigger or smaller compared to pure water drops? | [
"This is actually used to determine liquid surface tensions",
" (or ",
"this",
"). The pendant drop technique uses changes in the shape of a suspended liquid drop to determine a liquids surface tension. All suspended drops of liquid will deviate from a spherical shape as gravity pulls the drop down. The great... | [
"Depends how much liquid you put through the needle. The maximum volume of the drop for a given liquid and given needle geometry is a constant though and is directly proportional to the surface tension. So soapy water would produce smaller maximal volume drops of liquid."
] | [
"Thanks for your answers! Have a nice day"
] |
[
"Why do storms on our solar systems outer planets last so long?"
] | [
false
] | Title. Earth's toughest storms seem to only last a few weeks. But storms on the outer most planets have storms which have lasted for years or decades. What is so different about Earth? | [
"This is half remembered from a planetary science class a few years ago, so it may not be entirely accurate, but I think it’s related to the lack of land masses/analogous features to break up the storm. Hurricanes/typhoons on Earth form and strengthen over the ocean, then dissipate once they make landfall. There is... | [
"Both water and land absorb energy from wind through friction. The reason storms normally form and grow over the ocean is that the ocean supplies it with water vapor, which is the fuel the storm needs to grow and maintain itself. I guess the gaseous nature of the outer planets means less fiction for the driving for... | [
"This is a wild guess, but could it be slowed down because the outer planets are much colder, leading to slower reactions.",
"Also, storms on earth more or less always involve water or water vapour, whereas the atmospheres of other planets contain different compounds. Different materials behave differently.."
] |
[
"How are neutrinos formed?"
] | [
false
] | And I mean, not where they are formed, but how, and from what are they created from? Thanks in advanced! | [
"Kind of. When ",
" themselves decay (like muons or tau leptons) they produce a neutrino of their same flavour, and then a W boson that decays as iorg points out. So a muon decays to a mu neutrino, and a W",
" boson that decays to an electron and an electron anti-neutrino. It turns out that electron or muon or ... | [
"During beta decay, a W boson decays into a lepton and an antineutrino, or an antilepton and a neutrino."
] | [
"Is that the only way they can be created?"
] |
[
"Noether's Theorem - does the Principle of Relativity result in a conservation law?"
] | [
false
] | First, let me preface this by saying that I don't fully understand the math behind Noether's Theorem - I'm mostly hoping for a qualitative explanation (but math is good too :) As I understand it, , broadly stated, says that for any symmetry in physical laws, there is some corresponding conserved quantity - a conservati... | [
"I think it's a case where the math is at some level necessary. When we express physics in terms of say, a Lagrangian description, we can perform certain transformations on that description. For instance I can add +x, some arbitrary distance to all of the distances in the Lagrangian, and when I crank through the ma... | [
"It's sort of like this. Say you started from absolutely nothing and wanted to derive all of modern physics. Obviously you'd have to make some observations along the way, but a lot of physics consists not of equations derived directly from observation but rather equations that follow inevitably and logically from o... | [
"Recall, if you please, that Noether's theorem applies only to ",
" symmetries. What you're thinking of there would be a ",
" symmetry.",
"Consider a point on a circle. If you translate the point a little bit along the circle, you're effecting a symmetry of rotation about the center of the circle; you're not ... |
[
"Why is the Higgs Boson listed separately from the other Gauge Bosons in the Standard Model?"
] | [
false
] | [deleted] | [
"Because the Higgs boson is not a gauge boson.",
"Gauge bosons are spin 1 particles that are needed to ensure that a local symmetry holds.",
"The Higgs boson is a spin 0 particle and it does not serve to ensure the existence of a local symmetry."
] | [
"No, it doesn't have to be spin 1. In part, I was keeping things simple since OP seemed to be referring to diagrams of the Standard Model, but it's also the case that if I simply said \"gauge boson,\" in most contexts I would implicitly mean a vector field. But you're right to raise this.",
"Just to spell thin... | [
"Does a gauge boson need to be spin-1? I thought any boson with a gauge symmetry counted. (Of course, all the ones that appear in the standard model are spin-1 anyway.)"
] |
[
"How are the routes of blood vessels determined?"
] | [
false
] | One day I was looking at my hand and started wondering about my blood vessels. How are their routes determined? I would imagine they take the shortest and thus most economical route possible — as it seems to be everywhere in nature — to deliver oxygen etc. to the cells. How do they find that route? Is it possible to si... | [
"many MANY things in nature follow a similar fractal branching pattern. Your blood vessels, a tree's branches, your brain cells, the roots of many plants, etc. Even more, fractal patterns like this are found in tons of things outside of the biological sphere: ocean wave patterns, lightening bolts, earthquakes. So t... | [
"Blood vessels are a physical approximation of a kind of ",
"space-filling curve",
" (actually they are a not a \"curve\" in the mathematical sense but never mind). This is because every cell in your body needs oxygen, so needs to be close to a blood vessel, so on the large scale it looks like blood vessels fil... | [
"Follow up question: I've noticed before that the patterns in tree branches looks similar to the branching of a network of blood vessels. Is this just a coincidence, or is there some similar mechanism driving the patterns?"
] |
[
"How come we know so little on the whale shark?"
] | [
false
] | It's the biggest fish in the ocean, we know where to find them, where they nest(nest?) and exactly what they look like. Yet, no one really knows what's their life span(60-100 is no where near precise) or how they reproduce. Why don't we just track them? | [
"Because they only hang out near the surface to eat - After that, they dive up to ",
", where they do most of their living. We can't easily go that deeply, so as a result, we don't really know what they do down there (though we know by inference they mate and give birth down there, because they don't do it near ... | [
"Sharks actually avoid the limitations of air bladders by regulating their buoancy with their livers which contains large quantities of lightweight fluid lipids."
] | [
"That's really interesting and brings a bit of a followup question to my mind. ",
"Would animals that live so deep and then need to rise so far to eat not be at the risk of something like the bends from the sudden change in pressure?"
] |
[
"Are there materials that are good at conducting heat but not electricity or vice versa?"
] | [
false
] | null | [
"Actually there are materials that are designed to do exactly this for use in thermoelectric generators - they're called 'phonon glass electron crystals' or PGECs.",
"Other guy isn't wrong they are very much intrinsically related (it's called the wiedemann-franz law). Overall THERMAL conductivity is the sum of co... | [
"Diamond.",
"It has a thermal conductivity five times better than copper, with synthetic diamonds having the highest thermal conductivity of almost any substance known. Diamonds are also generally a very good electrical insulator, although some colors of diamond occur because of impurities that also make them a g... | [
"Not sure if there's materials where this mechanism is enough for them to be \"good\" heat conductors, but phonons (collective excitation of a crystal, where the atoms are moving relatively to each other) can also transfer heat within a solid. ",
"Edit : A ",
"link",
" where you can read something about how ... |
[
"Do planetary bodies in a \"stable\" orbit gradually move any closer to the body they orbit?"
] | [
false
] | [deleted] | [
"In the Newtonian approximation, it does not move closer. General relativity does it have it emitting gravitational waves, taking away this kinetic energy, and moving closer. However, this effect is incredibly tiny. We don't have to worry about spiraling into the sun, even on timescales of billions of years."
] | [
"There's discussion of how the effects scale at ",
"http://en.wikipedia.org/wiki/Gravitational_radiation#Power_radiated_by_orbiting_bodies",
"For some of these we can indeed measure as the orbital periods decrease. ",
"http://en.wikipedia.org/wiki/PSR_B1913%2B16"
] | [
"There's discussion of how the effects scale at ",
"http://en.wikipedia.org/wiki/Gravitational_radiation#Power_radiated_by_orbiting_bodies",
"For some of these we can indeed measure as the orbital periods decrease. ",
"http://en.wikipedia.org/wiki/PSR_B1913%2B16"
] |
[
"How do antidepressants make you gain weight?"
] | [
false
] | [deleted] | [
"Potentially, in a variety a variety of ways ",
"(taken from this recent consensus report on the subject)",
", although the unsatisfactory answer is that exact causes aren't really defined.",
"The mechanisms are related to both direct drug effects on appetite stimulation, or on normal resumption of appetite ... | [
"Various drugs have actions at different receptors. There appears to be at least a rough correlation between weight gain and blockade of specific dopamine (D2), histamine (H1), and serotonin (5-HT2C) receptors. Older tricyclics like amitriptyline, as well as the atypical drug mirtazapine, are the serious weight-gai... | [
"But from what I know most antidepressents make it much harder to work out due to less motivation, fatigue, among other side effects.",
"Why would antidepressants ",
" motivation? Increased motivation should be the whole point, no?"
] |
[
"Question about dissimilar metal corrosion..."
] | [
false
] | [deleted] | [
"The oxide finishes on both the aluminum and the fastener should prevent the formation of a galvanic cell. Even if galvanic corrosion occurs, the less-noble aluminum piece is much larger than the SS component, so the corrosion will be very slow.",
"Cheers."
] | [
"The general term for this is \"galvanic corrosion.\" ",
"Black oxide may react with the aluminum, but I can't find a definite answer. I'd repost to ",
"/r/engineering",
"."
] | [
"From what I can tell the black oxide coating should prevent corrosion between the two metals."
] |
[
"Why is there atomic motion? i.e. why do atoms move?"
] | [
false
] | null | [
"Because other atoms bump into them! The universe began at a nonzero temperature, which means that it began with some energy available for motion. Atoms have been jostling into each other ever since!"
] | [
"Yep! In each bump between atoms, energy is conserved. This means that what you started with is still the same amount of energy you'd have now (ignoring some important things like expansion of the universe that we can get into if you want, but it's a bit more complicated)."
] | [
"Sorry to continue to ask, Why?? ",
"You are saying that from the time of the big bang enough energy was imparted into the atoms of the universe to maintain constant motion?"
] |
[
"Would someone mind walking me through how they calculate the the time it took for light from a type 1a supernova to get to our planet?"
] | [
false
] | Just so you know what I know: I know what a standard candle is and why we need that to figure out how far away it is. What I don't know is the equation(s) that is used or how to use it. | [
"A number of methods",
" are used for determining distance."
] | [
"Thanks but that doesn't actually answer my question. Knowing the frequency will tell you how fast its traveling away from you, but not the distance. My question is how (what equations and how do you do the math with those equations) do we know how distant it is from us?"
] | [
"Thanks but that doesn't actually answer my question. Knowing the frequency will tell you how fast its traveling away from you, but not the distance. My question is how (what equations and how do you do the math with those equations) do we know how distant it is from us?"
] |
[
"Why do some LEDs remain on for seconds after they've been switched off?"
] | [
false
] | null | [
"It is really down to how the circuit is designed. Sometimes capacitors in the circuit (or more accurately the power supply) will continue to provide power after supply voltage is cut off. It doesn’t inherently have anything to do with the LEDs behaviour. The LED just glows when you apply voltage across it and will... | [
"Some white light LED's will exhibit ",
"phosphorescence",
" after they are turned off. This is because virtually all general illumination white LED's are a Blue, Violet, or UV LED with a phosphor painted on the chip. It is this phosphor that after glows. But, the ones I have seen do this are very faint. So if ... | [
"LEDs usually require a very small of current to operate.",
"This means that if there are any energy storing components in the circuit (capacitors or inductors) they can sustain the LED for a while after the power source has been turned off."
] |
[
"If you suddenly eat a lot more than you normally do in one meal, does your body process the extra calories normally?"
] | [
false
] | null | [
"While I'm not a metabolic or GI expert, perhaps I can shed some light.",
"The several segments of the GI system are specialized in specific things depending on which segment of the GI you're looking at. Example: stomach, mechanical, acidic and enzymatic digestion of large segments of food.",
"The segment you h... | [
"I can't speak to the ketogenic diet's efficacy, some people with IBD disorders do well on it but as far as weight loss its probably the sheer lack of carbs that does it. High protein, low carb content diets work basically all the same. The Adkins diet by nature was a ketogenic diet. It just didn't have it in the n... | [
"as a dietician...your body is very much capable of absorbing more than 4000 calories per day. The most I have seen a patient report consuming was nearly 7500 calories. This person had severe metabolic diseases. The 'extra calories' cannot simply pass though your system. If you start to eat more than you are capabl... |
[
"\"Black hole erupting for first time in 26 years\" - CNN.com Can someone tell me what it is that is actually being studied, and why it is interesting?"
] | [
false
] | I love that more and more science based news stories are being run in today's popular press, but I came across on the cnn front page this morning, and I honestly couldn't make heads or tails of what is actually going on. Has a particularly dense part of the accretion disk made it to the horizon and the radiation jets a... | [
"there is another star orbiting the black hole, and gas from the star is accreting onto its surface and igniting a fusion reaction",
"Just to clarify – NASA's terminology here was confusing, but what you described is a ",
"cataclysmic variable",
", in which accretion from a binary companion onto a white dwarf... | [
"Yes, in a reference frame where both us and the black hole are slow. And it's a nuclear reaction, not a chemical one."
] | [
"Well this is all the information they give so you can't really tell anything:",
"A NASA satellite detected the first sign of a black hole 8,000 light years away from Earth on Jun 15, 2015. Astronomers around the world are studying the event.",
"Googling that phrase reveals that V404 Cygni is emitting more x-ra... |
[
"Is it possible to create an optical filter that polarizes a narrow band of frequencies, but lets the rest of the light bandwidth to pass through unchanged?"
] | [
false
] | null | [
"If you're talking explcitly about the visible/nearvisible soectrum I don't know of one singular optical component that could be used to do this but I am willing to be corrected. I think you could do this if you have two polarizing beamsplitter cubes and some notch filters of the appropriate wavelength though. Will... | [
"Once I have done an experement with a simple linear polarizing photo lenses: i have used them as glasses with the angle between left polarizing axis being turned -45° while the right one +45°. The result was interesting, when looking thru these glasses a lot of surfaces appeared flickering (which makes sense consi... | [
"I think you could do this if you have two polarizing beamsplitter cubes and some notch filters of the appropriate wavelength though.",
"Ha! That's actualy very smart! That was exactly what I was interested in. Ideally I would like to have a sort of a film though :) ",
"Thanks!"
] |
[
"Do chickens have a limited supply of eggs throughout their life, or can they produce eggs as long as they have a functioning reproductive systema?"
] | [
false
] | null | [
"Birds, like humans, have a limited number of primary oocytes in their ovaries. But most of them don't live long enough to run out. ",
"This Slate article",
" that addresses your question says that some macaws, which are very long-lived, can run out of eggs, but the ",
"study they cite",
" is on humans, and... | [
"Thanks man, exactly what I was looking for"
] | [
"They make pretty good pets. They eat leftovers, bugs, and make fertilizer for gardens. Also, if you snuggle them when they are little, they will snuggle you when they are older. It's a tiny fluffy dinosaur that likes you and that's pretty cool."
] |
[
"How much DNA do we share with our maternal grandfather?"
] | [
false
] | How much DNA do we share with our maternal grandfather? EDIT! As a MALE, how much DNA do I share with my maternal grandfather. | [
"On average, an individual inherits 1/4 of their autosomal genome from a given grandparent. Each of your parents inherited exactly 1/2 of their genome from each of their parents, and you in turn inherited 1/2 of your genome from each of them.",
"However, due to the fact that genetic recombination during meiosis o... | [
"In humans, DNA is comprised of 46 chromosomes. X and Y are the two special chromosomes that determine gender, but they only represent a tiny portion (~5%?) of your total DNA. So in general, when talking about your DNA in total, gender makes no difference. You should, ",
" inherit 1/4 of your DNA from each of you... | [
"Sorry, see my edit.",
"How much DNA does a male share with his maternal grandfather?"
] |
[
"How were the very first computer languages/operating systems coded?"
] | [
false
] | Without any basis with which to code such complex programs, did they have to write everything in binary? Machine code? | [
"Assembly languages are just a step above binary. Assembly code is basically just CPU instructions expressed in human-readable text. Assembly \"compiler\" (actually ",
") is almost a 1:1 converter between text representation and binary. (It may also have some macros and other conveniences). People used to write e... | [
"The original way to program the oldest computers was to develop the instructions by hand and then wiring that in with ",
"wires into a plug board",
".",
"But later computers were initially programmed one byte at a time through front panel switches where you could usually set each bit of some structure such a... | [
"Of course you still need to write that first assembler, but as you can imagine it's not a very complicated program. And once you have it you can use that program to implement a more complicated assembler.",
"Ah, I never considered that possibility! It's fascinating to hear how coders worked around technical limi... |
[
"What is the difference in mental stimulation between reading and watching TV?"
] | [
false
] | I've noticed that I get sleepy when reading, even when I'm really enjoying the book - but within a minute of putting the book down and turning on the TV I'm suddenly wide awake and alert, even when I don't really care to watch TV. I'm curious what areas of the brain are stimulated in reading vs TV and why the latter jo... | [
"Not a top level answer here, but no one else has posted yet, so...",
"I'd say it's more likely that you're experiencing conditioning. For me, it's the opposite effect. I can read all night and not fall asleep, but I have grown accustomed to watching things when I go to bed, so I easily fall asleep watching TV. I... | [
"Good point - I've known people who would get droopy eyed five minutes into a movie and by an hour would be fast asleep, regardless of how loud or fast-paced the movie was. Maybe they're falling asleep to TV every night."
] | [
"This is not my field of expertise, but there are some observations I can pass along.\nReading is more active than watching TV. In reading your eyes take in visual stimuli that are first interpreted as characters / words, then integrated into sentences / images / concepts. It requires reference to the earlier parts... |
[
"How do we calculate current world population? Also, how accurate is that count?"
] | [
false
] | Burning question on my mind for awhile now. How do scientists calculate the current number of people on the planet? Is it some massive database, clever , or something else? | [
"Censuses, surveys and estimation. Most (all?) countries have some sort of census, literally asking everyone in them how many people are there. This can be validated by taking smaller populations and checking the numbers (like census data says 100 people live in this district, lets go door to door and physically co... | [
"This is not the type of question that a mathematician usually thinks about. Our work isn't about estimation, though it is relevant to statistics. I'm not saying this to be rude, just to point out that a different flair will get more relevant users seeing your question. I would suggest 'social science' as a more ap... | [
"Perhaps more like good than very good, although I suppose there's always the realistic enough hope that all the errors from individual countries roughly cancel each other out at a global level.",
"There's that old quote I can't remember about the English census in India - all the high level workings were really ... |
[
"If neutrons have no charge, what force causes them to stay in the nucleus of an atom? And do electrons ever come into contact with nuclei?"
] | [
false
] | null | [
"There is a nuclear force that bounds protons and neutrons together in a nucleus. You may have heard of the strong nuclear force that holds quarks together inside of protons and neutrons, and the nuclear force is a manifestation of that. It's similar to how van der Walls forces that keep atoms near each other are a... | [
"To go a little further, this idea drives nuclear reactions like fission and fusion. In a nucleus, you have two main competing forces; the nuclear force pulling in and the electric force pushing out. The nuclear force only acts over tiny tiny distances, about the width of an atom at maximum; neutrons contribute to ... | [
"Yeah that's not really accurate.",
"http://profmattstrassler.com/articles-and-posts/particle-physics-basics/virtual-particles-what-are-they/"
] |
[
"Do cats that get into a lot of fights learn 'combat moves' or is a cat's fighting style instinctual?"
] | [
false
] | Do cats that get into a lot of fights with other cats learn more lethal and effective tactics and styles, or is this all innate and genetic? | [
"What can be said for sure is they get used to it. That's what repetition training to harden soldiers is about. Take one guy who has stabbed a dozen guys and one guy who has only used a knife on steak. The action of plunging a knife into another human's body will be a more comfortable action for the former, just li... | [
"Do you really honk so ? "
] | [
"Do you really honk so ? "
] |
[
"What causes differences in virus longevity outside of the body?"
] | [
false
] | Herpes virus is said to only survive a few seconds outside of the body but the influenza virus can survive up to 24 hours and cold viruses survive for a week. What are the mechanisms and factors that both lead to the virus destruction and cause the difference in survival time? "It is highly unlikely that HSV will be pa... | [
"Actually HSV can survive longer than a few seconds outside the body. What's debatable is how long can a sufficient amount of the virus exists outside of the body, enough that can infect. That's also the question with other pathogens. Yes there are trace amounts hours or days later, but ate those amounts enough to ... | [
"Virus is a pretty broad term, and different types have very different structures and survival strategies. ",
"Viruses can encode their genetic information as either DNA or RNA, which can be either single stranded or double stranded, and if it's single stranded, it can be either the sense or antisense strand. Vir... | [
"I think this answer has a lot of merit, but HSV is an enveloped double-stranded DNA virus and has a short lifespan outside the body, while rhinoviruses (the cause of most colds) are single stranded, non-enveloped RNA viruses. I would suspect the major factor influencing viral lifespan may be the stability of the o... |
[
"If the universe is expanding, does that mean that new space is being created?"
] | [
false
] | If not, then what do we mean when we say the universe is expanding? What is actually happening? | [
"When we say the universe is expanding we mean that, if you were to go out into space, where there was nothing else around and place two beacons (which somehow didn't have any gravitational attraction to on another), one meter apart, and make sure they weren't moving relative to one another. Then later come back an... | [
"hmm does the PE lost between two bodies (say the 2 beacons) balance with the KE of the apparent velocity?"
] | [
"hmm does the PE lost between two bodies (say the 2 beacons) balance with the KE of the apparent velocity?"
] |
[
"My mind was blown after reading this article. Can someone tell me about your fascination with cellular automata?"
] | [
false
] | I was off this last week and decided to refresh my AI knowledge. I was looking for information on autonomous agents and stumbled upon cellular automata. I researched the topic in the past but not much in detail. For the past week, I really got into it and my mind is completely blown. Basically, cellular automata consis... | [
"I can't read any of Wolfram's stuff without thinking that he's a complete blowhard. Yeah, he's found some interesting stuff, but he crouches it all in this \"mind-blowing\" pseudo-philosophical speech that often has little to do with what he's actually describing. For instance, the discussion of \"purpose\" in the... | [
"From what little I understand, there's a school of thought in mathematical physics that holds that a (hitherto unspecified) cellular automaton is sufficient to simulate the universe. A corollary of this is that the fundamental operations of the universe are very simple, indeed. ",
"FWIW, it's a neat thought an... | [
"If you convert the digits of pi to binary, somewhere in that massive string of bits is a quicktime movie of your entire life, from birth to death. ",
"Now, if you only knew where to find it, we'd "
] |
[
"Why are there two spring tides per lunar month?"
] | [
false
] | I understand that a spring tide produced the highest high tides and the lowest low tides because the Moon and Sun are aligned. This makes sense when the Moon and Sun are both on the same side of Earth. However, I don't understand why a spring tide happens when the Moon is on the side opposite of the Earth from the Sun... | [
"Go back to the reason tides occur. The moon's force of gravity on the Earth is stronger on the side closest to it, and weaker on the side opposite. So while the solid Earth is pulled as a unit, the oceans are pulled more on the near side and less on the far side. That is why there are two tidal bulges, one on each... | [
"Extending on this to more directly answer OP's questions, the two bulges from the moon align with the two bulges from the sun twice per lunar month, and roughly add (spring). Between those two times (7 days before/after), they're opposed, making the tides smaller (neap).",
"Although the sun is of course much mor... | [
"This image (may) help to explain the forces at work.",
"http://www.lhup.edu/~dsimanek/scenario/tides02.gif",
"Because the centre of mass of the Earth-Moon system is not at the centre of the Earth, all the particles on and in the Earth experience an inertial force whose direction is opposite to the direction of... |
[
"What is going on in my brain that prevents my thoughts from flowing normally when I am nervous?"
] | [
false
] | Yesterday I had a job interview. I drove to the interview pretty confident. When I got there and sat down to three people asking me questions, I froze. My thoughts were no longer fluid. I forgot to tell them key elements of my work experience. I felt like I wanted to leave mid-interview. Afterwards, while driving... | [
"Hey good for you, you just discovered the difference between an alcoholic and most people. This is actually huge because people judge (like you were) based on their own experience and as such don't understand why an addict can't just stop. I mean, when I drink I can stop after one or two no proble, and so can ever... | [
"That's your amygdala's fight or flight kicking in. Your reptilian brain wanting you to get the fuck out of a stressful situation. I don't know what drugs would help, but as someone who gets anxious, shy, and stressed out in similar situations, learning to de-stress through breathing exercises has been crucial. I w... | [
"All of it applies to pot. It is actually a total misconception that marijuana is not that physically addicting. It has a clearly identified and diagnosable withdrawal syndrome that often makes it very difficult to quit for heavy users. It is not a highly addictive drug, but it does absolutely cause physical addict... |
[
"How do smoking/cancer probabilities work? If you smoke 40 cigarette a day from 16-50 are you 40x more likely to get lung cancer?"
] | [
false
] | I'm curious exactly how the advice plays out? If you are smoking 50 a day are you increasing your risks by 10% by going to 60 a day or is it diminishing returns? If there is a diminshing returns fator then is it an even line from 1 or does it curve in some way? Is smoking 5 a day only a little bit bitter than smoking 2... | [
"We measure smoking impact in terms of pack-years (packs/day * # of years). This accounts for the total amount of smoke exposure for the lung, but doesn't take into account time frame over which it occurs. Conceivably, a 20 pack-year history with of 20 packs/day over 1 year would be worse than 1pack/day over 20 y... | [
"Thanks for this and doing the research for me, it's really nice of you. With that said can you do me a favour and sum up what the quote is saying in total layman's terms? I know that sounds stupid but I'm still having trouble following it as it relates to my question. Is giving up one cigarette a day very benefici... | [
"How do smoking/cancer probabilities work?",
"They are primarily based on coincidental evidence.",
"If you smoke 40 cigarette a day from 16-50 are you 40x more likely to get lung cancer?",
"More likely to get lung cancer than whom?"
] |
[
"By how much is the Earth's magnetic field decaying yearly?"
] | [
false
] | null | [
"Saying that Earth's magnetic field is \"decaying\" is a bit misleading, since that sort of implies that it's currently decreasing and will never recover. The fact is that the strength of Earth's magnetic field ",
"changes all the time",
", sometimes getting stronger, sometimes weaker, and in a very unpredictab... | [
"That offcenter magma curling creates our magnetic field.",
"Magma is semi-molten rock found in the mantle. Magma does not create a magnetic field since it's not electrically conductive.",
"It's the convection and rotation of the liquid iron in Earth's outer core that generates our magnetic field through the dy... | [
"That offcenter magma curling creates our magnetic field.",
"Magma is semi-molten rock found in the mantle. Magma does not create a magnetic field since it's not electrically conductive.",
"It's the convection and rotation of the liquid iron in Earth's outer core that generates our magnetic field through the dy... |
[
"How I can I picture a radio wave in 3d space?"
] | [
false
] | I only ever see them depicted as sine waves online, but my guess would be that 'sine waves' are to radio waves as what '12' is to a carton of eggs. Is it possible to picture how they are around me in my environment? | [
"a good simple way is to imagine concentric spheres, where the surface of each sphere represents the positive waveform peak. then you can imagine an EM source in front of you that is more or less creating expanding bubbles, where each new bubble, \"wave,\" (sine wave positive peak) begins at the center of the previ... | [
"They do mess with the radio signal, definitely. They are both EM waves, and if two waves are in the same place, they interfere. UV is on the order of nanometers while FM radio is more like feet, so it is a million times smaller and very weak comparatively if all the way from the sun. But the real reason is that yo... | [
"The idea is that when projected into a single plane, the electric field component of a radio wave emitted by a source looks like a sine wave. But depending on which plane around the source you project into, you can get very different looking sine waves. This is the idea of a Fourier decomposition: a radio wave mig... |
[
"How long could you survive being in space unprotected?"
] | [
false
] | Sci fi movies have shown people surviving being in space for various amounts of time, from being killed instantly to being able to survive for a fairly long time. How quickly would being in space with just regular clothing actually kill you? | [
"You won’t explode, our bodies are pretty closed systems. You won’t freeze, heat transfer is far slower. If you had air in your lungs they’d explode due to gas expansion in low pressure. So I guess the answer is: how long can you stay conscious after completely exhaling? You’d just asphyxiate, so a minute or... | [
"Humans can survive a vacuum for more than a second. ",
"We even have a video of it",
".",
"Ionizing radiation within a second is completely negligible in space. It would only matter if you are next to a nuclear explosion, inside a star or in the core of a nuclear reactor - in all these cases you have other p... | [
"Humans can survive a vacuum for more than a second. ",
"We even have a video of it",
".",
"Ionizing radiation within a second is completely negligible in space. It would only matter if you are next to a nuclear explosion, inside a star or in the core of a nuclear reactor - in all these cases you have other p... |
[
"Do genetic diseases that don't show up until later in life get passed on more frequently?"
] | [
false
] | It seems like they would. Because if a diseases that showed up earlier in life, say while you were still fertile, then there's more of a chance of you dying/becoming incapacitated and not being able to reproduce and therefore not able to pass on the disease. | [
"Yes. Huntington's ~",
"~ disease usually starts after 30, which is a major factor in its continuing existence. You've already reproduced by the time it starts. When it starts before 20 (juvenile HD), there's much more strictly limited reproduction."
] | [
"HD positive here. Fwiw, I don’t like the name Huntington’s Chorea. We generally call it Huntington’s Disease. I know it seems nitpicky. Because it’s an orphan disease and the largest problem to research and quality of life is awareness it means more. The chorea name is from an era that had a much more limited unde... | [
"Likewise, genetic diseases that kill the person before they reach puberty are very rare because they can only enter the gene pool through random mutation (or carriers for recessive disorders)."
] |
[
"When obese people lose weight, one of the things they always say is how much more energy they have. How much of this energy is due to the loss of fat and how much is due to better exercise/diet?"
] | [
false
] | I'm basically wondering if the energy gain is because your body doesn't have the fat anymore or if it's because people are eating better/exercising more and not necessarily due to the fat loss. I'm also wondering how one would go about studying this. I was thinking giving some people minimal amounts of food to lose an... | [
"It depends. Given they lost weight through dieting and exercising - it's a combination of both. ",
"Primarily through weight-loss - To experience what they go through, put on a weighted vest, and play basketball in it for a few minutes. Then take it off and try to play basketball, it'll feel a lot easier to run ... | [
"Both. Jus carrying around less weight helps, eating healthier and exercise helps, but another thing to consider is the fat. Adipose tissue is a very active and dynamic organ, it is an endocrine organ in that it can release or downregulate many hormones and other chemical signals and can contribute to systemic infl... | [
"Either way, it's like a car. Old engine, full of gunk - low performance. Clean up the engine and tune it up - high performance."
] |
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