In as simple a way as possible, how are we able to tell the elementary make up of a planet using only a telescope?

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• In as simple a way as possible, how are we able to tell the elementary make up of a planet using only a telescope?
• In T-S or P-V diagrams often there is a number with an s next to it e.g. (5s connected with dashed lines with 4). What is the meaning of that 5s point and what is different from the regular 5?
• Apparently, for Conservation of Energy to be true, time translation symmetry must hold. However, does it really hold in an expanding universe?
• They say that a photon takes a million years to make it out of the Sun. But what does it even mean? How do we define that a particular photon now is the "same" photon that was there then?
• When you squint really hard, why do you hear a rushing wind like sound?
• Can you tell a sunrise from a sunset just from looking at a photograph?
• As a star begins to die, what are the effects on orbiting planets before the supernova?
• If I yawn while listening to music, there is a significant noticeable increase in my perception of the speed of the music. Why is this?
• How do we get high frequency (of few GHz) in electronic circuits ?
• If you're constantly growing and shedding skin cells, how come your freckles don't disappear/you don't grow new freckles?
• Why will a RH- mother with a RH+ fetus will have issues, and not a RH- fetus and a RH+ mother?
• If I have a description of a time-symmetric continous system (say, a set of random differential equations or a cellular automaton or something), how exactly would I get a formula for the conserved quantity as per Noether's Theorem?
• Why isn't there a 50% chance for 3 flipped coins to all land on the same side?
• If it were possible to stably break an atom apart into its fundamental parts, could we hypothetically put the existing particles back together into new atoms?
• If I attempted to hang myself from the ceiling of an elevator using a belt and it began to free-fall ... would there be slack in the belt?
• Can you get better at working with less sleep by training/practicing? i.e. Is there any long term adaptation to chronic sleep restriction?
• [Quantum Mechanics] Don't wave functions that can't be normalized contradict the possibility of an infinite universe?
• Is it possible to be shocked by an organisms spinal cord?
• Could 90-proof (95% ABV) Ethanol dissolve plastic?

In as simple a way as possible, how are we able to tell the elementary make up of a planet using only a telescope? Posted: 20 May 2017 05:19 AM PDT Just reading a story about how scientists used the Hubble telescope to view HAT-P-26b, s planet 440 light years away. They saw "distinct signatures of water in its atmosphere" and "found fewer heavy elements than they had expected". How can you do this using only a telescope? submitted by /u/nrthrn_pwrhs [link] [comments]

In T-S or P-V diagrams often there is a number with an s next to it e.g. (5s connected with dashed lines with 4). What is the meaning of that 5s point and what is different from the regular 5? Posted: 20 May 2017 04:53 AM PDT submitted by /u/Ratovandermir [link] [comments]

Apparently, for Conservation of Energy to be true, time translation symmetry must hold. However, does it really hold in an expanding universe? Posted: 20 May 2017 12:49 AM PDT On a relevant note: if we ever find out that the symmetry does not hold, and you can generate infinite energy, would it also invalidate the law that entropy always increases, thus freeing us of the danger of Heat Death, a la The Last Question? submitted by /u/thetimujin [link] [comments]

They say that a photon takes a million years to make it out of the Sun. But what does it even mean? How do we define that a particular photon now is the "same" photon that was there then? Posted: 20 May 2017 01:56 AM PDT When I'm doing photons-in-a-box problem with large enough number of photons, and I add a photon in, and later I let a photon out, there isn't really a sense in which I can say which one of the photons got out, any more that when I add 1+1=2, and then subtract 2-1=1, can I tell which one did I subtract (quite literally, this is how Fourier transform seems to work). They just blend into one wave until I decide to unblend them. I'm imagining the interior of the Sun to be a giant soup of photons, constantly absorbed, reemitted, bouncing around. Sometimes new photons are created by fusion, and sometimes some photons get out into the interstellar space, but how do we "track" them? submitted by /u/thetimujin [link] [comments]

When you squint really hard, why do you hear a rushing wind like sound? Posted: 19 May 2017 03:44 PM PDT submitted by /u/rpncritchlow [link] [comments]

Can you tell a sunrise from a sunset just from looking at a photograph? Posted: 19 May 2017 06:39 PM PDT submitted by /u/tretul [link] [comments]

As a star begins to die, what are the effects on orbiting planets before the supernova? Posted: 19 May 2017 09:52 PM PDT Say an Earth-like planet (read: Earth) is orbiting a star of 1 solar mass that is nearing it's death. At what point does life on this planet cease to exist (read: no longer habitable)? What exactly happens to scour all possibilities of survival? Or would all be well and good until the supernova begins? submitted by /u/Sigral [link] [comments]

If I yawn while listening to music, there is a significant noticeable increase in my perception of the speed of the music. Why is this? Posted: 19 May 2017 04:48 PM PDT This happens every time, regardless of how tired I am, I use headphones when I listen to music, if I'm moving my head to the beat or something, that keeps in time with the music and I perceive my movement as happening faster too. The increase is between about 20-50%, it varies but it's always a significant difference. submitted by /u/ScornMuffins [link] [comments]

How do we get high frequency (of few GHz) in electronic circuits ? Posted: 19 May 2017 06:55 PM PDT I know about crystal oscillators, that can make frequencies up to 100 MHz and about PLLs, Schmitt-triggered inverters and stuff like that. But I couldn't find a good explanation and put this together to figure out where all does high freqs come from. I guessed it has to do with all the before mentioned concepts, so I would like to clear it out. submitted by /u/sekirce3 [link] [comments]

If you're constantly growing and shedding skin cells, how come your freckles don't disappear/you don't grow new freckles? Posted: 20 May 2017 04:03 AM PDT So it's my (possibly inaccurate) understanding that freckles are a result of a certain cluster of cells producing more melanin and appearing darker than the rest of your skin cells. So wouldn't you eventually shed all the dark cells that composed a freckle, or new cells that you produced could mutate to be darker? As someone who has had the same trademark nose freckle all their life, I know this to be untrue, but why??? submitted by /u/jellybones01 [link] [comments]

Why will a RH- mother with a RH+ fetus will have issues, and not a RH- fetus and a RH+ mother? Posted: 19 May 2017 04:22 PM PDT Their blood mixes together, so can't the fetus create antibodies for the mother's foreign blood? submitted by /u/tommyzat [link] [comments]

If I have a description of a time-symmetric continous system (say, a set of random differential equations or a cellular automaton or something), how exactly would I get a formula for the conserved quantity as per Noether's Theorem? Posted: 19 May 2017 11:12 PM PDT submitted by /u/thetimujin [link] [comments]

Why isn't there a 50% chance for 3 flipped coins to all land on the same side? Posted: 19 May 2017 05:01 PM PDT I know this might seem like a dumb question, but here's my logic; 'When you flip 3 coins, at least 2 of them are guaranteed to land on the same side, so surely the other coin has a 50% chance of landing on the same side as the other two.' Now, we can tell from flipping 3 coins several times, that this is probably an incorrect assumption. What I want know is, what is the error in my logic? submitted by /u/smearglexd [link] [comments]

If it were possible to stably break an atom apart into its fundamental parts, could we hypothetically put the existing particles back together into new atoms? Posted: 19 May 2017 09:38 AM PDT For example, take Helium 4 with 2 protons and 2 neutrons. If we broke that apart into its individual components, could we piece it back together into 2 atoms of deuterium? submitted by /u/Topicu [link] [comments]

If I attempted to hang myself from the ceiling of an elevator using a belt and it began to free-fall ... would there be slack in the belt? Posted: 19 May 2017 11:39 AM PDT submitted by /u/_Thrawn [link] [comments]

Can you get better at working with less sleep by training/practicing? i.e. Is there any long term adaptation to chronic sleep restriction? Posted: 19 May 2017 07:16 AM PDT Obviously, mental and physical performance will decline during the first few days of sleep restriction. Eventually, presumably after a few weeks, performance will cease to decline and stabilize at a minimum. The key question is: if you sustain this sleep restriction for a longer period of time (months to years), will performance ever increase above this minimum? and by how much? Is it possible to regain baseline performance if you limit sleep restriction to a small level? So for example, if you reduced your sleep time from a normal 8 hours to 7 hours for a period of a year, can you regain the same mental performance as before? If you go from 8 to 5 hours, can you perform as if you've only lost an hour of sleep? Effectively, you would be practicing working in a sleep deprived state, presumably adapting your mind and body in the hope of reducing or eliminating the effects of sleep restriction. submitted by /u/elsjpq [link] [comments]

[Quantum Mechanics] Don't wave functions that can't be normalized contradict the possibility of an infinite universe? Posted: 19 May 2017 12:31 PM PDT The simplest case is a constant potential. We get that the wave function is proportional to exp[ikx] (and exp[-ikx]), so the square of its absolute value is constant, i.e. uniform distribution. But a uniform distribution is impossible in an infinite universe, as it can't be normalized. Doesn't that contradict an infinite universe? submitted by /u/yarinch [link] [comments]

Is it possible to be shocked by an organisms spinal cord? Posted: 19 May 2017 11:45 AM PDT I was talking to my dad earlier and he told me that one time he caught a catfish and gutted it, etc. Eventually, he grabbed its spinal cord and was shocked. I'm assuming this has everything to do with the nervous system of the fish but not exactly sure how it would shock my dad? submitted by /u/StudentBill [link] [comments]

Could 90-proof (95% ABV) Ethanol dissolve plastic? Posted: 19 May 2017 10:25 PM PDT If so how long would it take to dissolve threw a plastic bottle? submitted by /u/PM_UR_ARMPITS [link] [comments]

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If each day is only 23h56m4s, over the course of 4 years, we accumulate 95.7 hours of unaccounted time when approximating each day to 24 hours. We give ourselves one extra day in February, which accounts for only 24 hours of that extra time, but where does that extra 71.7 hours go?

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• If each day is only 23h56m4s, over the course of 4 years, we accumulate 95.7 hours of unaccounted time when approximating each day to 24 hours. We give ourselves one extra day in February, which accounts for only 24 hours of that extra time, but where does that extra 71.7 hours go?
• Why are the physical electromagnetic fields only the real part of E and B?
• Is the earth still cooling from its formation? If so, does that mean eventually all tectonic activity will cease and our liquid mantle will solidify?
• What's the max signal frequency on a DSL wire?
• What is the cause of diffusion and osmosis? How does it work?
• How do dogs make ATP?
• Why is silver chloride so insoluble?
• What causes you to remember dreams?
• Since everything with mass has a gravitational pull, does this mean that Pluto has a pull on me currently?
• How much man-made space debris is there?
• If electrons are so much smaller than than protons and neutrons, why can't we easily see atom nuclei with an electron microscope?
• What happens with perspective in relation to a reflection in a mirror?
• At what point are planets considered to have "cleared the neighbourhood"?
• If black dwarfs did exist, wouldn't they blend in with the cosmic background radiation, cooling off to this temperature?
• Is there interpretation of quantum mechanics that violates principle of realism?
• Is the photon really massless?
• If the only thing keeping an electron in the lowest orbital from crashing into the nucleus is the quantization of energy, how can electron capture occur? Does the electron just go through a series of quantum jumps to the nucleus?
• Is it possible for an element with zero protons and zero electrons to exist/have existed?
• Can an isotope have a negative number of neutrons?
• Does pilot wave theory work with experimental results of (delayed choice) quantum erasers?
• How do animals that camouflage really well find mates?
• How does "polishing out" scratches work on a molecular level?

If each day is only 23h56m4s, over the course of 4 years, we accumulate 95.7 hours of unaccounted time when approximating each day to 24 hours. We give ourselves one extra day in February, which accounts for only 24 hours of that extra time, but where does that extra 71.7 hours go? Posted: 19 May 2017 07:01 AM PDT This also means that our calendar should shift over 3 days every 4 years, changing the "location" of the seasons in our man made calendar submitted by /u/fornoggg [link] [comments]

Why are the physical electromagnetic fields only the real part of E and B? Posted: 19 May 2017 02:16 AM PDT This says that the physical fields are only the real part of E and B, but this is not obvious to me. Since eix = cos(x) + i sin(x) We get an imaginary part of the fields in the picture, but somehow these aren't actually a part of the fields, or how should i interpret i? submitted by /u/Physix_R_Cool [link] [comments]

Is the earth still cooling from its formation? If so, does that mean eventually all tectonic activity will cease and our liquid mantle will solidify? Posted: 18 May 2017 08:01 AM PDT submitted by /u/cats_on_t_rexes [link] [comments]

What's the max signal frequency on a DSL wire? Posted: 19 May 2017 03:44 AM PDT Edit: OK, I'll try to rephrase, because the DSL apparently has complex techniques for multiplexing & reducing echo & transmission errors.. Let's assume the simplest case, an analogue signal carrying a digital signal in a wire. What's the minimum frequency of the analogue signal that can carry a bandwidth of x Kbps? Original question: So the telco is saying that my copper wire can provide up to about 35Mbps of DSL connection speed. Does this mean that the carrier signal in the wire is at 35MHz, a little higher, or double of that? Why? submitted by /u/KRBT [link] [comments]

What is the cause of diffusion and osmosis? How does it work? Posted: 19 May 2017 05:13 AM PDT I know the general gist of how diffusion/osmosis works, I just don't know why it works like it works. submitted by /u/PersonalComputerG [link] [comments]

How do dogs make ATP? Posted: 19 May 2017 07:10 AM PDT Every being needs energy. Animals cells make ATP from sugar and oxygen. So where do dogs (and other meat eaters) get sugar from if they eat exceedingly meat. submitted by /u/LeonardoM011 [link] [comments]

Why is silver chloride so insoluble? Posted: 19 May 2017 04:02 AM PDT My guess is that the sizes of the silver and chloride ions are just right so the crystal is very stable and thermodynamically favoured over free ions? submitted by /u/nicktohzyu [link] [comments]

What causes you to remember dreams? Posted: 18 May 2017 07:20 PM PDT Having a conversation with the boyfriend just before, we both dont remember alot of our dreams, However almost every night this week both of us have have had weird dreams that we remember the next day, Very unusual for us. Is it something we have eaten? Lack of sleep? Too much sleep? Chemicals in the body that are being produced? Please shed some light on this, this is weird and unusual, im spending half of my day trying to wrap my head around weird ass dreams! submitted by /u/zoeysheree1993 [link] [comments]

Since everything with mass has a gravitational pull, does this mean that Pluto has a pull on me currently? Posted: 18 May 2017 07:12 PM PDT To be more specific, I know everything that has mass has a gravitational pull, even atoms. I wanted to know, regardless of how small, if extremely far away planets/stars have an effect on us? It got me thinking that if time is infinite, will everything with mass, every atom, and every quark eventually come together as one big mass in space? submitted by /u/smallwhales [link] [comments]

How much man-made space debris is there? Posted: 18 May 2017 03:44 PM PDT Pictures I see on the internet show space debris covering most of the surface. Obviously, the actual debris isn't that large or we'd be seeing it in the sky everyday. So, how much is actually there? What happens to it? How do we avoid the debris hitting spacecraft? submitted by /u/Impatient_Nerd [link] [comments]

If electrons are so much smaller than than protons and neutrons, why can't we easily see atom nuclei with an electron microscope? Posted: 19 May 2017 04:48 AM PDT submitted by /u/TheMoonLord [link] [comments]

What happens with perspective in relation to a reflection in a mirror? Posted: 19 May 2017 04:29 AM PDT What I mean by this is the vantage point at the mirror or where you are standing? For example, when you are standing in front of a large hill and there are mountains in the background you can still see the mountains if you are far enough away from the hill, but if you get too close to the hill the mountain will disappear. If you stand just outside range of seeing the mountain and put a mirror (hypothetically tall enough) where you should be able to see the mountain if you were standing, would you see the mountain top or not? [http://imgur.com/a/sqFeR](Pictures of the scenarios I am trying to explain) submitted by /u/Ilovechinesefood69 [link] [comments]

At what point are planets considered to have "cleared the neighbourhood"? Posted: 19 May 2017 03:22 AM PDT The Jupiter is a planet, but it still gets hit by comets, which have regular orbits of their own. Saturn's ring is unstable enough that there may even be a new satellite forming out of the mass. Very slowly, but the Moon's orbit is slowly changing and away from the Earth. And then there are the occasional asteroid impacts. So what makes the term "clearing the neighbourhood" important in deciding if a body is a planet? submitted by /u/seasaltandpepper [link] [comments]

If black dwarfs did exist, wouldn't they blend in with the cosmic background radiation, cooling off to this temperature? Posted: 18 May 2017 09:16 PM PDT submitted by /u/sbundlab [link] [comments]

Is there interpretation of quantum mechanics that violates principle of realism? Posted: 18 May 2017 02:58 PM PDT Quantum mechanics violates principle of local realism[1]. So far, we cannot really say whether QM violates only locality or realism or both. My understanding is, that it depends on interpretation of QM - e.g. Bohmian mechanics is nonlocal but doesn't violate principle of realism (if I am mistaken here, please correct me). My question therefore is whether there exists any specific interpretation of QM where we can say that it violates principle of realism (not necessarily only principle of realism)? Also, it seems to me that various authors treat principle of locality and principle of realism differently, meaning that they are using different definitions of these two concepts. I believe that Bell defined what he meant by principle of locality in [2] - I believe he meant principle of locality in the sense of local causality (though I am not absolutely certain by it, so if anybody can correct me in this I would appreciate it). I also believe that principle of realism are basically hidden variables, am I correct? [1] - pdf link to Bell's paper: "On the Einstein-Podolsky-Rosen Paradox" [2] - pdf link to Bell's paper: "The Theory of Local Beables" submitted by /u/Enfili [link] [comments]

Is the photon really massless? Posted: 18 May 2017 02:35 PM PDT When photons enter a medium they couple to phonons and acquire an effective mass. In vaccum however they move at c and are massless. But according to QFT the vacuum is also somewhat like a medium, so can photons in a vacuum really be considered massless or should we think of them having an effective mass as well? I know that there are fundamental principles behind the concept of a maximum speed of information exchange and that electromagnetic waves in a vacuum travel at that speed, but is that actually the end of the story? submitted by /u/reedmore [link] [comments]

If the only thing keeping an electron in the lowest orbital from crashing into the nucleus is the quantization of energy, how can electron capture occur? Does the electron just go through a series of quantum jumps to the nucleus? Posted: 18 May 2017 11:21 AM PDT submitted by /u/SpicesAndHRBs [link] [comments]

Is it possible for an element with zero protons and zero electrons to exist/have existed? Posted: 19 May 2017 12:44 AM PDT Similar to the element zero on the Mass Effect games. Is it possible for an element like that to exist and if so, how would it interact with other atoms and molecules? submitted by /u/Davideroni [link] [comments]

Can an isotope have a negative number of neutrons? Posted: 18 May 2017 08:40 PM PDT proton = upQuark + upQuark + downQuark neutron = downQuark + downQuark + upQuark A nucleus can be described by its number of upQuarks and downQuarks, if their positions are a blur. On the other hand, many videos show protons and neutrons as nonoverlapping balls, which I take to mean vibrations that attract and repel at various distances. Can a neutron and proton in the same nucleus swap positions? submitted by /u/BenRayfield [link] [comments]

Does pilot wave theory work with experimental results of (delayed choice) quantum erasers? Posted: 18 May 2017 02:17 PM PDT I've recently stumbled upon the 'dead but not dead' theory of pilot wave theory in QM. Allthough I did hear that apparently relativity doesn't work well with this theory, I wondered if the theory is consistent with measurement results of (delayed choice) quantum erasers. (I put delayed choice between parentheses because that specific experiment might be considered separately). I'm not too deep into QM, I followed courses on nanoelectronics and I have some experience with Schrodinger equations but in general, my math in QM is not up to speed. I'd like to hear the answer with the least amount of concessions as possible. So if complicated math is needed, feel free to. I'll just dive into it and see what I can learn. submitted by /u/TunnelFET [link] [comments]

How do animals that camouflage really well find mates? Posted: 18 May 2017 03:10 PM PDT The same defense mechanisms which hide them from their predator/prey could also work against them and hide them from potential mates. This could also be very bad for the genetic pool if these animals can only breed with the immediate group they hang out with, right? submitted by /u/_rb [link] [comments]

How does "polishing out" scratches work on a molecular level? Posted: 18 May 2017 12:33 PM PDT Hey today I read an article that said that you can try to polish out small scratches in gold. As gold is quite soft that makes at least some sense however I wondered how that works on a molecular level (u can be precise I am a physicist myself). It also stated that it is somewhat even possible with glas, does anyone know if that is true? Cheers submitted by /u/lschozar [link] [comments]

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They say that to test String Theory, we need to build a particle accelerator as large as out galaxy. Is it a technical limitation or a fundamental one?

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• They say that to test String Theory, we need to build a particle accelerator as large as out galaxy. Is it a technical limitation or a fundamental one?
• Why do I feel like I need to cough when I stick a q-tip in my ear?
• Why do we have to kill a horse when it broke its leg? What is the difference in biological processes between man and horse in bone mending?
• How dangerous is uranium/uranium oxide to handle?
• Light beam propulsion without lasers?
• Why does boiling water make so much sound?
• Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology
• Where do prions originate from?
• Can air "hold" alcohol (ethanol) like it can water at room temperature?
• Can we only detect planets in systems that we see edge on?
• If you stacked a lot of microscopic organisms, would you eventually be able to see them? What would they look like?
• Why should death from dehydration have to be so suffering?
• What happens on an atomic scale when water is boiled?
• Use of the delta function in QM?
• [Physics] How do whispering gallery mode resonators in lasers work?
• how does chirality come into play when manufacturing pharmaceuticals?
• How does the weak force works ?
• What makes some adhesives reusable and some useless unless reapplied?
• If I aim a 'typical' laser-pointer into the night sky, assuming no clouds, how far will it travel/be detectable into space?
• Can swordfish see their own bill?
• What in the human anatomy of fingers makes it easier to get a ring on than off?

They say that to test String Theory, we need to build a particle accelerator as large as out galaxy. Is it a technical limitation or a fundamental one? Posted: 17 May 2017 10:09 AM PDT submitted by /u/thetimujin [link] [comments]

Why do I feel like I need to cough when I stick a q-tip in my ear? Posted: 17 May 2017 01:32 PM PDT I know you're not supposed to do it, but I still do. When I stick a Q-tip in my ear, I get this overwhelming urge to cough. Why is that? submitted by /u/Rottendog [link] [comments]

Why do we have to kill a horse when it broke its leg? What is the difference in biological processes between man and horse in bone mending? Posted: 18 May 2017 03:12 AM PDT submitted by /u/Arrp00994 [link] [comments]

How dangerous is uranium/uranium oxide to handle? Posted: 17 May 2017 08:40 AM PDT At 38:55 of the below video, it is said that people wear gloves when handling uranium to protect the uranium from being contaminated, rather than wearing gloves to protect themselves from the uranium. It is said that since uranium's half-life is in the billions of years, it isn't that radioactive. This sounds hard for me to believe, as I thought uranium was very dangerous to handle. Is it true that uranium isn't that radioactive? That gloves are worn to protect the uranium, and not the human? Also, is uranium oxide - which is what the pellets in the video are - the same as uranium in terms of safety? https://youtu.be/H6mhw-CNxaE submitted by /u/Fyreborn [link] [comments]

Light beam propulsion without lasers? Posted: 18 May 2017 05:57 AM PDT We now have the capability to do laser launch. The problem is the initial cost outlay for the lasers is still prohibitive to launch a sizable payload. The estimate of the payload you can launch to Earth orbit dependent on laser power is about 1 kg per megawatt. So to launch thousand kilo payloads would require a gigawatt laser power levels. At current prices this would cost billions of dollars. But is it possible to do it without using lasers, just using high intensity noncoherent light focused by mirrors or lenses? I wondered about this because of two reports I saw doing a web search actually on optical communication: InfiniLED MicroLEDs achieve 300 W/cm2 output density from tiny source. The MicroLEDs semiconductor manufacturing process includes construction of a parabolic reflector to enable optimal light control and high efficiency from micro-meter-sized LEDs. Published on:Jan 29, 2013 By Maury Wright http://www.ledsmagazine.com/articles/2013/01/infiniled-microleds-achieve-300-w-cm-sup-2-sup-output-density-from-tiny-source.html and: Optical communications using coherent and non-coherent light. http://modulatedlight.org/optical_comms/optical_about.html The first report discusses micro-scale LED's whose light output scales up to 300 W per square centimeter, 3 megawatts per meter. From the appearance of these micro-scale LED's, they should permit simple automated production to produce many copies to cover a macro-scale area to generate light even at gigawatt power levels. The second report discusses experimentation that suggests atmospheric dispersion is actually worse for lasers than for noncoherent light generated by LED's. See for instance the video in Fig. 2 on this page. The advantage of the lasers however is that generating a parallel beam, you can use a parabolic mirror to focus the light at the focal point (more precisely at the Airy disk). Still, nevertheless a parabolic mirror will still focus a large portion of the light at the focal point even for noncoherent light. So the question is if the beam is noncoherent, how much of the light can still be focused at the focal point (Airy disk)? submitted by /u/RGregoryClark [link] [comments]

Why does boiling water make so much sound? Posted: 18 May 2017 03:52 AM PDT submitted by /u/uncut_onyx [link] [comments]

Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology Posted: 17 May 2017 08:04 AM PDT Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Biology, Chemistry, Neuroscience, Medicine, Psychology Do you have a question within these topics you weren't sure was worth submitting? Is something a bit too speculative for a typical /r/AskScience post? No question is too big or small for AAW. In this thread you can ask any science-related question! Things like: "What would happen if...", "How will the future...", "If all the rules for 'X' were different...", "Why does my...". Asking Questions: Please post your question as a top-level response to this, and our team of panellists will be here to answer and discuss your questions. The other topic areas will appear in future Ask Anything Wednesdays, so if you have other questions not covered by this weeks theme please either hold on to it until those topics come around, or go and post over in our sister subreddit /r/AskScienceDiscussion , where every day is Ask Anything Wednesday! Off-theme questions in this post will be removed to try and keep the thread a manageable size for both our readers and panellists. Answering Questions: Please only answer a posted question if you are an expert in the field. The full guidelines for posting responses in AskScience can be found here. In short, this is a moderated subreddit, and responses which do not meet our quality guidelines will be removed. Remember, peer reviewed sources are always appreciated, and anecdotes are absolutely not appropriate. In general if your answer begins with 'I think', or 'I've heard', then it's not suitable for /r/AskScience. If you would like to become a member of the AskScience panel, please refer to the information provided here. Past AskAnythingWednesday posts can be found here. Ask away! submitted by /u/AutoModerator [link] [comments]

Where do prions originate from? Posted: 17 May 2017 08:53 PM PDT submitted by /u/forealzman [link] [comments]

Can air "hold" alcohol (ethanol) like it can water at room temperature? Posted: 17 May 2017 08:30 PM PDT Hey guys. I know this question highly depends on the temperate and probably air pressure or something, so lets say typical summer day, 25°C (=77°F or 298,15°K), normal pressure. I place a bowl of pure alcohol in a room. Will alcohol "go" into the air like water would? (Sorry for the words in "", I'm from germany and english isn't my native language so i was missing a few vocabularies :> ) submitted by /u/Truckermouse [link] [comments]

Can we only detect planets in systems that we see edge on? Posted: 17 May 2017 05:13 PM PDT I've heard that we use the transit method for identifying planets passing in front of stars. Does this mean that we can only detect planets if their orbital plane is along our line of sight? submitted by /u/nyxo1 [link] [comments]

If you stacked a lot of microscopic organisms, would you eventually be able to see them? What would they look like? Posted: 17 May 2017 07:28 PM PDT Assuming they don't move or run away, what would happen if you stacked (or piled up) a lot of microscopic organismic or just microscopic "things" in general. Disregarding the improbability/impossibility of finding that many of the organism, would you eventually pile up enough to be able to see them? Would it look like a solid mass? Bonus: what would it feel like? submitted by /u/DasBeasto [link] [comments]

Why should death from dehydration have to be so suffering? Posted: 17 May 2017 07:12 PM PDT I have heard that dying from dehydration is one of the most uncomfortable and gruesome death possible. I understand some aspects on why a person would show symptoms because it is the body's way of warning the user. However, if a person is severely dehydrated then the body should just accept that the person is probably stuck somewhere that has no water. The body should release large amount of endorphin and make the death as serene and comfortable as possible instead of having the person suffer through death. I do not understand this from a biological standpoint since starvation has the body release endorphins after a while since it recognizes that death is inevitable. submitted by /u/Grandtier [link] [comments]

What happens on an atomic scale when water is boiled? Posted: 17 May 2017 11:55 AM PDT So my college entry biology professor (with a doctorate) just told my summer school class that when water boils, the hydrogen and oxygen atoms split and bind to each other, forming H2 and O2. I have always been taught that water vapor is just water molecules that are heated to a gaseous form. Also, if what he said is true (which at this point, I have trouble believing) than why does the ensuing H2 gas and O2 gas not react with my kitchen stove and blow my house apart when I do something like cook pasta? submitted by /u/scarredFalconer [link] [comments]

Use of the delta function in QM? Posted: 18 May 2017 04:44 AM PDT I've only ever come across this function in Control Engineering for system response, however I think I remember someone in another thread mentioning its use in quantum mechanics, can anyone tell me how it is used in that field? Thanks submitted by /u/spk96 [link] [comments]

[Physics] How do whispering gallery mode resonators in lasers work? Posted: 18 May 2017 04:31 AM PDT How do they work and how are they able to get ultra narrow linewidth, high Q factor? Links to articles, journals or books are highly appreciated. Thanks in advance. submitted by /u/Quanta314 [link] [comments]

how does chirality come into play when manufacturing pharmaceuticals? Posted: 17 May 2017 10:10 PM PDT I understand what it is I just dont get how a mirror of a molecule would come into play. are they connected? do they come in pairs and the other molecule has to be flushed out? does it just happen by accident that a molecule chiral partner slips into the mix and isnt easily spotted because of its likeness? please explain. submitted by /u/endlessunshine833 [link] [comments]

How does the weak force works ? Posted: 17 May 2017 11:53 PM PDT I manage to understand the other 3 interaction but the weak force still remains a mystery, i was wondering if you van answers these following questions: 1. What are the mechanism of the weak force ? 2. What field of boson transmit it ? 3. How does the weak force affect our lives ? 4. Can or Have we harnessed the weak force in any way ? submitted by /u/Mikhail_Mifzal [link] [comments]

What makes some adhesives reusable and some useless unless reapplied? Posted: 17 May 2017 06:53 PM PDT In the case of sticky notes, they can be stuck several times before losing their "stick", while things like super glue stick once and never again. submitted by /u/Unfortunate_taco [link] [comments]

If I aim a 'typical' laser-pointer into the night sky, assuming no clouds, how far will it travel/be detectable into space? Posted: 17 May 2017 06:40 PM PDT Obviously I know this depends on the sensitivity of the object "detecting it" but in general how far would a laser-pointer pointed into the sky get before it could no longer be detectable. If it's necessary to put a metric on it "how far until the human eye would no longer notice its presence?" submitted by /u/gett-itt [link] [comments]

Can swordfish see their own bill? Posted: 17 May 2017 03:32 PM PDT submitted by /u/CronosDage [link] [comments]

What in the human anatomy of fingers makes it easier to get a ring on than off? Posted: 17 May 2017 11:17 AM PDT submitted by /u/tarmitch [link] [comments]

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