How did Archimedes calculate the volume of spheres using infinitesimals?

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• How did Archimedes calculate the volume of spheres using infinitesimals?
• What is the smallest amount of matter needed to create a black hole ? Could a poppy seed become a black hole if crushed to small enough space ?
• What is limiting people from making room temperature superconductors?
• How did scientists in ancient India (~1500 BCE), precisely predict trajectory of the Moon and other celestial events without the use of technology like telescopes, computers and satellites?
• How would Helium-3 be mined on the moon or the outer gas giants Jupiter, Saturn?
• For the vast majority of Earth's history, there was no life on the surface. What did the landscape of the Earth look like before plant life, or land animals?
• Why do bases "eat" flesh?
• Is it easier for an exhaust fan to pull air through a duct rather than pushing it into the duct?
• How would one objectively determine if the sample size of a set of data is "good enough"?
• What does the Schrodinger equation mean and what does it tell us?
• If blood is taken from a human corpse several hours after death, can lab tests detect that the blood sample was taken from a dead person?
• An event happens with constant frequency F. I am uncertain about the exact value of F, as represented by the probability distribution P(F). I start observing at a random moment. After S seconds, the event occurs. What is my new subjective distribution of P(F)?
• Which is stronger, covalent or ionic bonds?
• What determines the difference of energy between two quantum energy levels?
• What does it mean that the phase velocity or the group velocity of matter waves can be greater than the speed of light?
• Can natural subterranean aquifers be artificially refilled?
• Confused by this video by Leonard Susskind on all symmetries in physics being approximations. How can this be right?
• If we're inside the Milky Way, why does it look like it's "over there"?
• Why does there appear to be water erosion at the edge of continental plates under the ocean?
• Is there a Gauss's Law for Light?
• Can some Taylor series be interpreted as Legendre-Fourier series?
• Does the angle of the tube affect Poiseuille's Law?

How did Archimedes calculate the volume of spheres using infinitesimals? Posted: 09 Feb 2017 09:25 AM PST submitted by /u/TimAnEnchanter [link] [comments]

What is the smallest amount of matter needed to create a black hole ? Could a poppy seed become a black hole if crushed to small enough space ? Posted: 10 Feb 2017 05:40 AM PST submitted by /u/vangyyy [link] [comments]

What is limiting people from making room temperature superconductors? Posted: 09 Feb 2017 08:07 PM PST According to my physics teacher if someone was to come up with such a thing then overheating anything wouldn't be a problem and that person/group would become trillionaires overnight. submitted by /u/gamblingthroaway [link] [comments]

How did scientists in ancient India (~1500 BCE), precisely predict trajectory of the Moon and other celestial events without the use of technology like telescopes, computers and satellites? Posted: 09 Feb 2017 10:55 PM PST They even created a precise calendar, based on these predictions, which holds true till today, several thousands of years later. I am very intrigued as to how was it possible at that point in time. submitted by /u/imkaush [link] [comments]

How would Helium-3 be mined on the moon or the outer gas giants Jupiter, Saturn? Posted: 09 Feb 2017 07:44 PM PST It comes up in fiction, but what exactly would the process of mining Helium 3 look like? submitted by /u/AndyLC [link] [comments]

For the vast majority of Earth's history, there was no life on the surface. What did the landscape of the Earth look like before plant life, or land animals? Posted: 09 Feb 2017 03:12 PM PST This is a strange question, but it's bothering me. I don't think I've ever seen an artists impression/depiction of what Earth's surface has looked like for most of its lifetime. I remember in Walking with Monsters they depicted it as a dry, desert, arid landscape. What would it have looked like? If the Earth was stripped bare, would the rocks be grey? Yellow? Brown? Would it be dusty, muddy, or sandy? submitted by /u/Pluto_and_Charon [link] [comments]

Why do bases "eat" flesh? Posted: 09 Feb 2017 10:30 AM PST with acids it is because the released H-atoms react with the proteins and breaks up the pepitde bond. but how do bases work? submitted by /u/theluke112 [link] [comments]

Is it easier for an exhaust fan to pull air through a duct rather than pushing it into the duct? Posted: 09 Feb 2017 06:52 PM PST I'm planning on adding a new bathroom exhaust fan and somehow I'm thinking that it if it were mounted closer to the roof (in the attic) it would be able to pull the humid air out of the bathroom through the duct more efficiently. As opposed to being ceiling mounted, it would have a harder time pushing air through the duct. Is there any basis for this? submitted by /u/qazpod [link] [comments]

How would one objectively determine if the sample size of a set of data is "good enough"? Posted: 09 Feb 2017 05:17 PM PST submitted by /u/confusedandventing [link] [comments]

What does the Schrodinger equation mean and what does it tell us? Posted: 09 Feb 2017 01:10 PM PST I am beginning quantum mechanics and we have been studying the Schrodinger equation pretty extensively. But I am confused about what this equation represents and why can't we derive it? submitted by /u/tokamak_2000 [link] [comments]

If blood is taken from a human corpse several hours after death, can lab tests detect that the blood sample was taken from a dead person? Posted: 09 Feb 2017 10:41 AM PST I'm aware that blood coagulates several hours after death. So does a blood sample taken from a person who has been dead for several hours contain markers that distinguish it from blood taken from a live person (or very recently dead person), and can these markers be detected through forensic testing? submitted by /u/PetrichorGirl [link] [comments]

An event happens with constant frequency F. I am uncertain about the exact value of F, as represented by the probability distribution P(F). I start observing at a random moment. After S seconds, the event occurs. What is my new subjective distribution of P(F)? Posted: 09 Feb 2017 10:57 AM PST submitted by /u/thetimujin [link] [comments]

Which is stronger, covalent or ionic bonds? Posted: 09 Feb 2017 09:42 PM PST submitted by /u/EragusTrenzalore [link] [comments]

What determines the difference of energy between two quantum energy levels? Posted: 09 Feb 2017 04:33 PM PST I want to find out what makes different items have different colors. I already found out that they only absorb light that can help the electron "jump" to another quantum energy level but what determines the difference between the quantum energy levels? submitted by /u/ThimoSpeelman [link] [comments]

What does it mean that the phase velocity or the group velocity of matter waves can be greater than the speed of light? Posted: 09 Feb 2017 01:54 PM PST In my textbook today I read that in matter waves that the phase velocity and group velocity can exceed the speed of light but we wouldn't be able to attain any information if it did. So in order to transmit information the wave must be modulated in some way. What does this mean? Matter waves can travel faster than light but don't have any information? I though nothing can exceed the speed of light? submitted by /u/tokamak_2000 [link] [comments]

Can natural subterranean aquifers be artificially refilled? Posted: 09 Feb 2017 05:38 PM PST If we had a supply of fresh water, could we pump that water back into the aquifer at the rate we took it out? Would the ground that has sunk because the water level lowered rise back up? submitted by /u/1SweetChuck [link] [comments]

Confused by this video by Leonard Susskind on all symmetries in physics being approximations. How can this be right? Posted: 09 Feb 2017 04:01 PM PST https://youtu.be/45vCHttuUnQ Susskind says that all symmetries (continuous symmetries and symmetries that are about interchanging two objects) are really always approximate or are always broken. He gives this example about nearly massless quarks which I understand just fine. But isn't CPT symmetry exact as far as we know? And what about space translational and rotational symmetry which give rise to conservation of linear and angular momentum? submitted by /u/ultraking_x2 [link] [comments]

If we're inside the Milky Way, why does it look like it's "over there"? Posted: 09 Feb 2017 09:19 AM PST Here is how the Milky Way typically looks from our solar system: https://i.imgur.com/PgYKaSd.jpg If we're on the outer edge of the milky way, why does it feel like the photographer is sitting way outside the galaxy in space, and looking upon it from afar? I picture myself on a giant dinner plate, just in from the rim a few hundred meters. I look off to the center, and then look down along the floor and see plate all the way up to my feet. I turn around, and see plate extending off to the rim. It looks like all the area around me is plate, but the view we have of the galaxy looks like we're perched far away in deep space. Why doesn't it appear as though some big spiral arm is extending towards us and enveloping us? Like this: https://i.imgur.com/tFMp00H.png submitted by /u/Freeloading_Sponger [link] [comments]

Why does there appear to be water erosion at the edge of continental plates under the ocean? Posted: 09 Feb 2017 09:48 PM PST The most notable area that I see on google maps is the west coast of north america where it looks like rivers flow across the pacific plate. I know freshwater is less dense than saltwater, so why would this happen? submitted by /u/YumeCookie [link] [comments]

Is there a Gauss's Law for Light? Posted: 09 Feb 2017 12:44 PM PST If we state Gauss's Law as Surface integral of E dot dA = Q / (epsilon_0) Can we say this? Surface integral of Illuminance dA = Luminous Flux Does that equation hold true? I figured the dot product could go because illuminance is a scalar. Is there some other expression that it equals, such as Q/(epsilon_0) for Gauss's Law or 0 for his law for magnetism or mass for -4piGM for Gauss's Law for Gravity? tl;dr: I'm trying to mentally relate the concepts of luminous flux and illuminance to electric flux and electric field. submitted by /u/66bananasandagrape [link] [comments]

Can some Taylor series be interpreted as Legendre-Fourier series? Posted: 09 Feb 2017 12:34 PM PST Suppose you have a function that can be expressed as a Taylor series as well as a Legendre-Fourier series. Since the Legendre series is just a series of Legendre polynomials, we can group coefficients and rewrite it as a power series. And since this "new" series must be equal to the Taylor series (at least for |x| < 1), the coefficients must be equal. Taylor series are said to NOT be series of orthogonal functions, but in this case, it seems that it is equivalent to one. So can Taylor series be interpreted as Fourier series in this way? Or am I being loose with a definition or something? submitted by /u/bellsandwhistles [link] [comments]

Does the angle of the tube affect Poiseuille's Law? Posted: 09 Feb 2017 09:26 AM PST Hi, Just wanted to check that Poiseuille's Law concerning flow of fluids through tubes isn't affected by the angle of the tube. All the diagrams that I've seen show horizontal tubes, and I would like to know if the law works the same if the tube is vertical, below the water source. Thanks for any help :) submitted by /u/Millman97 [link] [comments]

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Why is this specific air intake design so common in modern stealth jets?

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• Why is this specific air intake design so common in modern stealth jets?
• Why do scientists use rudimentary outlines of images when using the preferential looking paradigm as opposed to actual photos?
• I just read that Venus has about 90 atmospheres pressure at the surface. Knowing that Venus is about the same size as Earth, how can it have such a deep, or heavy, atmosphere?
• How can a drum spinning with tubes entering and exiting the same point not twist the tubes around each other?
• Can you "swim" in space? In a space station?
• Why is the logarithm formulation in Self Information optimal compared to other functions? (Information Theory)
• Why do electrons and protons have precisely equal but opposite electrical charge but with different masses?
• What is the theory behind large velocity/frequency widths for masers?
• What qualities make an animal more likely to be domesticated?
• How do Earth's Satellites stay in orbit? [Physics]
• Is it common to use PSI even in Metric countries?
• Do animals that have ranges or territories continually try to expand their range?
• How do we know what sea surface temperatures were in the late 1800's and even the early 1900's?
• If you are looking at an LED which changes color at a given interval, how short would that interval have to be to have the colors appear as only white light?
• How do the joints of a hummingbird deal with all the wear?
• How long do solar panels last before needing to be replaced and is this currently a barrier to investing in solar in terms of cost efficiency?
• How are quarks arranged inside protons/neutrons? Are there quark orbitals/clouds, just like how electrons are arranged atoms?
• What causes some rocks/minerals to naturally form with right angles and straight edges?
• Over what distance does rayleigh scattering have an effect distinguishable by naked eye?
• Why does wood turn "grey" after being outside long enough?
• How far can a human scream/ howl travel?
• Why do some 'old' people look very young for their age?
• What happens to a metal lattice as an EM wave hits it?

Why is this specific air intake design so common in modern stealth jets? Posted: 08 Feb 2017 07:37 AM PST https://media.defense.gov/2011/Mar/10/2000278445/-1/-1/0/110302-F-MQ656-941.JPG The F22 and F35 as well as the planned J20 and PAK FA all use this very similar design. Does it have to do with stealth or just aerodynamics in general? submitted by /u/bratimm [link] [comments]

Why do scientists use rudimentary outlines of images when using the preferential looking paradigm as opposed to actual photos? Posted: 08 Feb 2017 10:59 PM PST In an experiment called Do Infants Possess an Evolved Spider-Detection Mechanism? scientists show rudimentary outlines of spiders to infants and track the infants's eyes to test if humans have an innate spider-detecting mechanism. They show reconfigurations of the schematic spider image as well to see if the infants have a tendency to pay more attention to the original spider schematic than to the reconfigured "random images. I was wondering why they had to go through the whole process of creating and using a schematic spider as opposed to just using pictures of actual spiders. At first I thought they only did this so that they could reconfigure the image, but then I realized they could easily do that with a picture of a real a spider. Later they used pictures of real spiders to prove that infants recognized the schematic spider as a spider, as opposed to seeing them as unrelated shapes. Thanks in advance for answering. submitted by /u/CuckedByJaredFogle [link] [comments]

I just read that Venus has about 90 atmospheres pressure at the surface. Knowing that Venus is about the same size as Earth, how can it have such a deep, or heavy, atmosphere? Posted: 08 Feb 2017 09:03 PM PST submitted by /u/MacaRat [link] [comments]

How can a drum spinning with tubes entering and exiting the same point not twist the tubes around each other? Posted: 08 Feb 2017 08:05 PM PST I am a nursing student, and today I was shown an aphairesis machine. The thing that blew my mind was the centrifuge. It had the whole blood coming in, and the plasma and red blood cells coming out 2 tubes, so 1 tube entering, 2 tubes leaving. They are continuous with no breaks. The RN showing it to me couldn't explain it to me and I can't figure it out. Here is a picture of the thing not in motion: http://imgur.com/o36RgZZ Here is a gif of it in motion: http://imgur.com/omHPJoR EDIT: Here is a video of a full unit showing plasma donation. it doesnt show the full disassembly of the unit unfortunately. Its to give you an idea of whats up top. https://www.youtube.com/watch?v=s4MSK4Q-El4 submitted by /u/lostintime2004 [link] [comments]

Can you "swim" in space? In a space station? Posted: 08 Feb 2017 07:34 PM PST So I was watching Chris hadfield singing in the space station, "standing" still keeping contact with the station with his feet. For a moment he let go and stood still, floating. This is where I wondered, what if he is out of reach of anything in the station? if he can't pull nor push himself. He is breathing freely (so there are gaz) so I guess he could "swim" inside the space station. It wouldn't be very useful because of the low density but I suppose he could try. Does that mean that in space, if you're not moving relatively to something that could save your life 2 meters away, you couldn't do shit about it? (looking for answers on reddit, I found people suggesting farting as a way to generate thrust). Thank you for your replies. submitted by /u/Bnthefuck [link] [comments]

Why is the logarithm formulation in Self Information optimal compared to other functions? (Information Theory) Posted: 08 Feb 2017 09:54 PM PST Recently I read up a bit of Information Theory which talks about the concept of Entropy. However I am unable to find a satisfying answer that the logarithm of the event probability, i.e. log(1/p), is the optimal choice. Now I know that it has several attractive properties including: The joint information of two independent event is the sum of the individual information (i.e. H(A and B)=H(A)+H(B)) The rarer the event, the more information content it has. If all outcomes are equally likely, then the entropy (which is defined on the self information) is maximized. From the data compression/transmission standpoint, it makes sense to allocate less number of bit for frequent outcome but more for rare event. If that is the rationale behind self information, then what stops us from allocating even more to rare event, say move another 1 bit from the frequent event to rare event? I suppose it is related to some kind of lower bound on how many bit I have to allocate for any event. submitted by /u/ultradolp [link] [comments]

Why do electrons and protons have precisely equal but opposite electrical charge but with different masses? Posted: 09 Feb 2017 12:58 AM PST submitted by /u/valor400 [link] [comments]

What is the theory behind large velocity/frequency widths for masers? Posted: 08 Feb 2017 09:01 PM PST I was going through this paper where the velocity of the maser is on the order of 80 000 km/s due to cosmic expansion (z = 0.265). But as you may see in Figure 1, the velocity width of the signal is about 2200 km s-1 . When plugging those values for this OH transition into here, I get frequency widths on the order 10 MHz. Are not these frequency widths quite large for megamasers? I was under the impression these masers resulted in narrow lines. Also, I was led to believe there is velocity coherence in masers, but in this case, how can a maser have a velocity width of 2200 km s-1 ? Would not the molecules moving at different velocities result in collisions and dephasing throughout the masing region resulting in thermal equilibrium eventually? Even when looking at Figure 1, why does there appear to be two peaks as opposed to a single pulse as normally observed? And finally, can the velocity widths theoretically be even higher than 2200 km s-1 ? I suppose a better initial question is what is causing these widths of 2200 km s-1 in the first place? submitted by /u/CallMeDoc24 [link] [comments]

What qualities make an animal more likely to be domesticated? Posted: 08 Feb 2017 02:54 PM PST Why can't all animals be domesticated? Are there any animals that could be domesticated but are not yet? submitted by /u/skugga_ [link] [comments]

How do Earth's Satellites stay in orbit? [Physics] Posted: 08 Feb 2017 06:09 PM PST I understand that there is a sling-shot effect, but what I don't comprehend is how objects that stay within the orbit of Earth don't either get pulled towards the planet from going too slow, or get shot into,space from going too fast. in other words, how to these satellites maintain the correct speed? submitted by /u/xLikeABox [link] [comments]

Is it common to use PSI even in Metric countries? Posted: 09 Feb 2017 03:07 AM PST PSI seems to be used in general conversation, even outside the USA. Thanks! submitted by /u/tombh1 [link] [comments]

Do animals that have ranges or territories continually try to expand their range? Posted: 08 Feb 2017 04:20 PM PST For example, lions have their pride areas. Does the actually area the pride controls increase over time (barring competition) or only stay large enough to support the pack and adequately protect? submitted by /u/TheTimolosophy [link] [comments]

How do we know what sea surface temperatures were in the late 1800's and even the early 1900's? Posted: 08 Feb 2017 10:52 AM PST I guess more specifically: Was measurement technology robust in the late 1800's? When did use of buoys begin? What did we use before weather satellites? Where do we get the historic data from (a national organization, or random sources)?? submitted by /u/pnr32 [link] [comments]

If you are looking at an LED which changes color at a given interval, how short would that interval have to be to have the colors appear as only white light? Posted: 08 Feb 2017 10:54 AM PST Asking for a project, just need a general limit to color perception in time. Thanks! submitted by /u/CatharsisBlue [link] [comments]

How do the joints of a hummingbird deal with all the wear? Posted: 08 Feb 2017 10:25 AM PST I was having a discussion about hummingbirds and one of the questions that came up was how hummingbirds deal with the consequences of the repetitive motion at the shoulder joint. In humans, the repetitive motion quickly wears cartilage down resulting in severely decreased mobility but it doesn't seem that hummingbirds suffer from the same issue. submitted by /u/SarkhanDragonSpeaker [link] [comments]

How long do solar panels last before needing to be replaced and is this currently a barrier to investing in solar in terms of cost efficiency? Posted: 08 Feb 2017 06:28 AM PST submitted by /u/Fikkia [link] [comments]

How are quarks arranged inside protons/neutrons? Are there quark orbitals/clouds, just like how electrons are arranged atoms? Posted: 08 Feb 2017 01:34 PM PST They're both point particles so... they both have probability clouds? submitted by /u/StopSpyingOnMeDad [link] [comments]

What causes some rocks/minerals to naturally form with right angles and straight edges? Posted: 08 Feb 2017 02:53 PM PST I saw a picture of naturally occurring fluorite in a chemistry textbook and wondered why is it naturally forms a near-perfect cube. submitted by /u/kmn3713 [link] [comments]

Over what distance does rayleigh scattering have an effect distinguishable by naked eye? Posted: 09 Feb 2017 12:42 AM PST Since blue light is scattered more due to it's wavelength over a certain distance, is red light (from a source about as bright as carbeams) for example visible to further distances relevant on earth or does this only come into account over greater distances? I saw in a video that blue light from an emergency vehicle is only visible up to an altitude of 500m (1640 feet) whereas red light reaches 3 times higher. Is this true? Thanks in advance. submitted by /u/lucidgazorpazorp [link] [comments]

Why does wood turn "grey" after being outside long enough? Posted: 08 Feb 2017 01:40 PM PST I have seen that newer wood turns into a grey color if it stands outside long enough. I want to know why this happens, and if this happens to other materials. submitted by /u/Pills_your_friend [link] [comments]

How far can a human scream/ howl travel? Posted: 08 Feb 2017 11:23 PM PST I know that howler monkey voices can be heard for miles. But if a human - male or female (on the ground) were to howl in a similar manner, how far would it travel? It would be helpful to know the distance for different landscapes, such as in a forest, in a city, flat farmland, mountains, at sea/ by the coast. Is there a type of landscape/location that is best for reducing the distance the sound could be heard from? And is there an outright best sort of location to hear this voice? How much does weather affect distances? submitted by /u/Miabard [link] [comments]

Why do some 'old' people look very young for their age? Posted: 08 Feb 2017 11:13 PM PST Let's say the age we're talking about is 65. I've noticed that some people around this age look in their early 50s, others in their early 80s! Is this mostly down to UV/ toxin damage and genetics, or do personality and things like social status and employment make a significant difference? submitted by /u/Miabard [link] [comments]

What happens to a metal lattice as an EM wave hits it? Posted: 08 Feb 2017 02:24 PM PST So anything you got from EM to Quantum would be nice. What is permeability and permittivity according to perturbation theory? What "losses" occur in a metal lattice and how do you characterize them? What happens to the states of bonds as the wave function changes about them? Anything and everything helps, Thanks! submitted by /u/charlesischuck [link] [comments]

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Are spiders attracted to heat sources?

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• Are spiders attracted to heat sources?
• Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science
• Is there a name for a series of primes created by adding a digit in front of the previous one?
• Does a vacuum have energy?
• What would happen if antimatter was absorbed into a black hole?
• How are drug quantities measured and filled to the correct size?
• How were quantum orbital shapes discovered/figured out?
• How exactly are quantum tunneling and nuclear fusion related?
• Why in electricity and magnetic field calculations there are pi?
• What makes computers slow down so much over time?
• Is there any celestial object with a strong positive or negative electric charge?
• How can a photon have a mass of zero without violating the mass - energy equivalence?
• How can a single speaker make multiple tones at the same time?
• If neutrinos can move through vast quantities of mass without interacting with it, how are they detected?
• In the theory of Pangaea, why did the earth have such a large land formation on one side of the planet and expansive ocean across the rest?
• Why don't we scale wind turbines down?
• How do whales fend off attacks by other sea creatures?
• How do B lymphocytes divide to form memory cells AND plasma cells?
• How do we achieve average global temperatures from 1900?
• Is adding two images in image space the same as doing so in frequency space?

Are spiders attracted to heat sources? Posted: 07 Feb 2017 06:29 PM PST Pardon my stupid, I can't remember my 6th grade science. Does cold weather affect spiders negatively? Will they seek out a heat source for survival/feeding/breeding? submitted by /u/tinyhousebuilder [link] [comments]

Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science Posted: 08 Feb 2017 07:04 AM PST Welcome to our weekly feature, Ask Anything Wednesday - this week we are focusing on Physics, Astronomy, Earth and Planetary Science 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]

Is there a name for a series of primes created by adding a digit in front of the previous one? Posted: 08 Feb 2017 12:07 AM PST Hi, I was reading some cryptography question in another subreddit and it talked about using really long primes to do the encryption, and how making the primes longer would make the system exponentially harder to solve. This got me thinking as to whether there could be series of primes as in the title, for example 3->13, 7->37, but with longer runs, and if they've a name or if they've been studied at all. I used base 10, but I'm interested in any other base as well. Edit/tldr: I'm looking for a prime p with m digits such that p mod 10n for all n<=m is prime Thanks! submitted by /u/browsy_ [link] [comments]

Does a vacuum have energy? Posted: 07 Feb 2017 03:52 PM PST submitted by /u/Joshbecker117 [link] [comments]

What would happen if antimatter was absorbed into a black hole? Posted: 07 Feb 2017 07:32 PM PST I'm assuming different sizes/amounts of antimatter and black holes will have a different result too submitted by /u/Chennsta [link] [comments]

How are drug quantities measured and filled to the correct size? Posted: 08 Feb 2017 02:28 AM PST For example. On a box of Chlorphenamine Maleate (an antihistamine) it reads 4mg Tablets. I am aware that 4mg is an incredibly small mass. So if I have a tablet of this then what actually makes up the tablet, because the tablet presumably weighs a lot more than 4mg? Also, how do they precisely put such a small mass of the actual drug component into a tablet? submitted by /u/Cutter1998 [link] [comments]

How were quantum orbital shapes discovered/figured out? Posted: 07 Feb 2017 04:11 PM PST How were the possible orbital shapes (probability regions of finding electrons) in atoms found? Don't some shapes overlap with others? If you would add all them up in a dense atom, would there still be a place where the probability of finding an electron would be 0? What kind of experiments were done to verify their shapes? submitted by /u/tiagovtristao [link] [comments]

How exactly are quantum tunneling and nuclear fusion related? Posted: 07 Feb 2017 09:58 PM PST I was taught that quantum tunneling is necessary for nuclear fusion to happen but I am unsure how that exactly happens. submitted by /u/tokamak_2000 [link] [comments]

Why in electricity and magnetic field calculations there are pi? Posted: 07 Feb 2017 10:59 PM PST First of all. English isn't my first language and i'm writing from phone so sorry for that. My question is. Im at the moment studying materialscience in university and our physics class are now studying electricity and magnetic fields generated by electricity. But in calculations there are almost allways pi. Why pi is prominent in these calculations and why "nature" "uses" it in these calculations. For example "biot's and savart's law" (i have no idea what this is in english, but trying to translate it from finnish). submitted by /u/Khrysoar [link] [comments]

What makes computers slow down so much over time? Posted: 07 Feb 2017 04:15 PM PST For example, a 5 year old macbook pro that has been factory reset, even running the same OS version and applications, seems slower than it did when it was new submitted by /u/mopperv [link] [comments]

Is there any celestial object with a strong positive or negative electric charge? Posted: 07 Feb 2017 06:01 PM PST submitted by /u/DownFalldotcom [link] [comments]

How can a photon have a mass of zero without violating the mass - energy equivalence? Posted: 07 Feb 2017 12:41 PM PST Photons are particles without mass. But whenever a system emits one, it loses a small fraction of its energy, and therefore its mass. However, the photon lacks mass and only transports energy, so conservation of energy is given, while conservation of mass is violated. If the photon is added to another system, the other system gains (although very little) mass. So is a photon transporting mass without actually having any? I'm really confused right now, and might be I just miss something simple here. Thanks in advance for any answers! EDIT: Thank you all for taking the time to write these answers down. They did indeed clarify a lot, concerning my question and giving a lot of further, interesting information! submitted by /u/TrueCursion [link] [comments]

How can a single speaker make multiple tones at the same time? Posted: 07 Feb 2017 03:51 PM PST How are, for example, the bass line, drums, guitar and vocals all generated all from one speaker at the same time? submitted by /u/To-Dare-Is-To-Do [link] [comments]

If neutrinos can move through vast quantities of mass without interacting with it, how are they detected? Posted: 07 Feb 2017 10:10 AM PST Also, if there is some form of interaction, what exactly occurs? submitted by /u/Thermonuclear_Potato [link] [comments]

In the theory of Pangaea, why did the earth have such a large land formation on one side of the planet and expansive ocean across the rest? Posted: 07 Feb 2017 08:27 AM PST Or were there other smaller continents that were consumed by the continents we know now when Pangaea broke up? submitted by /u/Likesorangejuice [link] [comments]

Why don't we scale wind turbines down? Posted: 07 Feb 2017 05:51 PM PST From my understanding, a changing magnetic field makes a steady current. So a wind turbine works when the wind pushes the fan. The fan turns a magnet that's placed near a loop of wire which then generates a current. However, if we were to make it faster, wouldn't that make the current higher and as such the power higher? So in that case, why don't we make the wind turbine smaller and it will oscillate more, thus creating more energy? submitted by /u/whitelife123 [link] [comments]

How do whales fend off attacks by other sea creatures? Posted: 07 Feb 2017 10:00 AM PST They're big and slow, what prevents a shark from just taking a while bite by bite? submitted by /u/THEN_THE_ACID_KICKED [link] [comments]

How do B lymphocytes divide to form memory cells AND plasma cells? Posted: 07 Feb 2017 11:12 AM PST If B lymphocytes divide by mitosis, which produces genetically identical copies of the original cell, how can two different types of cell be formed?? submitted by /u/smrnnm [link] [comments]

How do we achieve average global temperatures from 1900? Posted: 07 Feb 2017 10:16 AM PST I do believe in climate change of about 1 degree celsius over the past 100 years, most likely caused by pollution. I do not (yet) believe that we know within a fraction of a degree what the global temperatures were 100 years ago... can anyone convince me? My belief in climate change is based solely on very recent science, but it would be nice to learn why I keep seeing studies like this that start in 1880. If the short answer is 'from weather records' can anyone provide a link to the records from, say, January 1st 1990? Or at least the number of stations that were providing temperature data? Someone used this report to argue that there were 4349 stations collecting monthly average temperatures since 1850, but that seems unlikely... and if true would most likely be lots of temperatures for population centers and few for unpopulated places like deserts, oceans, mountains, Antartica etc. It just seems incredibly time consuming and difficult to calculate the average Earth temperature for a year, considering the temperature fluctuates wildly from hour to hour, day to day, location to location. Wouldn't it require at least one thousand weather stations taking measurements the same way, at the same times, several times per day, every day of the year, in an even spread across the Earth's surface (including parts of the Earth's surface that weren't set foot upon at the time)? Sorry for so much doubt, but I really need some education on this subject, and I've not had any luck getting a response from Google or r/ history. Thanks for any assistance! submitted by /u/chainsawx72 [link] [comments]

Is adding two images in image space the same as doing so in frequency space? Posted: 07 Feb 2017 05:51 PM PST Hey there. I have some doubts regarding image algebra. First, as the title says, is adding (or subtracting) two images in frequency space the same as doing it in image space? By frequency space I mean Fourier domain. One particular example is, if I obtain the low-frequency components of an image, if I subtract that image with its original, do I get the high-frequency components? Or is that only true if I perform the subtraction in frequency space? Second, I was having a discussion with a friend about addition between images. He says that addition of images is the same as the mean of the two images, which I think it's not correct. Well, mean involves a division that addition does not have. But, is he right? Is it the same (mean and addition) if we force normalization of the images along the process? Thanks a lot! submitted by /u/Yukito01 [link] [comments]

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