question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Suppose I'm on a non rotating planet. I have two identical, perfect watches. I synchronize them. Then I throw one of them into the air and catch it. Does the one I throw into the air gain or lose time with respect to the one I was holding?</p> | g16388 | [
0.013244661502540112,
0.015094262547791004,
0.01708837039768696,
0.03897338733077049,
0.05498695373535156,
0.0607847161591053,
0.061372507363557816,
-0.041080817580223083,
-0.014869911596179008,
-0.014841229654848576,
-0.0751509964466095,
0.013782446272671223,
-0.04857660084962845,
0.01778... |
<p>An asteroid was recently discovered that is in a <a href="http://arxiv.org/abs/1104.0036">horseshoe orbit with respect to the earth</a>. Is there an intuitive explanation for these orbits? It seems that the earth acts as a repulsive force where one would expect gravity to be attractive. From the above linked article... | g16389 | [
0.056656207889318466,
0.07125988602638245,
-0.0032224180176854134,
-0.050335630774497986,
0.05198366194963455,
0.04581216722726822,
0.0263838991522789,
-0.03700556606054306,
-0.031542468816041946,
-0.04262375086545944,
0.007685687392950058,
-0.002155139110982418,
0.09518272429704666,
0.003... |
<p>Given a solid whose interior is a hollow sphere with perfectly reflecting mirrors. A small hole is drilled in the sphere and a photon is sent in at some angle. Will it always eventually exit through the hole it entered?</p>
<p>Is there any arrangement of mirrors one can place inside the sphere such that the photon ... | g588 | [
-0.011357526294887066,
0.03211051970720291,
0.02291232906281948,
-0.01274825632572174,
-0.02661239542067051,
0.024682560935616493,
0.038289472460746765,
0.012058558873832226,
-0.013135792687535286,
-0.008555262349545956,
-0.04119371995329857,
0.007090360391885042,
-0.036044903099536896,
-0... |
<p>i mean let be the integral</p>
<p>$$ \int_{0}^{\infty} \frac{p^{3}}{(p^{2}+m^{2})^{2}} $$</p>
<p>logartihmic divergence but if a apply differentiation with respect to $ m^{2} $ i get</p>
<p>$$ \int_{0}^{\infty} \frac{-2p^{3}}{(p^{2}+m^{2})^{3}}=I(m) $$ wich is convergent so</p>
<p>is the real integral then of th... | g16390 | [
0.04884936660528183,
0.013818487524986267,
-0.018624717369675636,
-0.023878734558820724,
0.007320016622543335,
0.029573235660791397,
0.01515744999051094,
-0.050819069147109985,
-0.053771648555994034,
-0.011575372889637947,
-0.08295436948537827,
0.02202458865940571,
0.01758808083832264,
0.0... |
<p>I calculated that in the focal spot of such a laser the critical energy density would be met.</p>
<p>Will these black holes really move at the speed of light, just as the the photons that made them? The conservation of momentum seems to give the speed of light here.</p>
<p>But if the black hole is a "matter-like" ... | g16391 | [
-0.0011426351265981793,
-0.007115976419299841,
0.03729448467493057,
0.022354982793331146,
0.031187018379569054,
-0.0014432102907449007,
-0.028286200016736984,
0.02141360007226467,
-0.021856117993593216,
0.02631809562444687,
0.05219164118170738,
-0.027495374903082848,
0.056658755987882614,
... |
<p>Masses of elementary particles in standard model are strange numbers. Is it possible to obtain these masses in string theory (presumably by using very few number of input parameters)?</p> | g16392 | [
-0.013368910178542137,
0.01714327000081539,
0.026521233841776848,
-0.02591613680124283,
0.056616999208927155,
0.01289874967187643,
-0.02738344669342041,
0.02399584650993347,
-0.03544040024280548,
0.025674007833003998,
-0.054462090134620667,
-0.009150219149887562,
0.018868964165449142,
-0.0... |
<p>Einstein originally thought that special relativity was about light and how it always travelled at the same speed. Nowadays, we think that special relativity is about the idea that there is some universal speed limit on the transfer of information (and experiments tell us that photons, the quanta of light, move with... | g16393 | [
0.012104175053536892,
0.052833009511232376,
-0.0014792990405112505,
0.06098414957523346,
0.008204828016459942,
0.010795743204653263,
0.014083989895880222,
0.054516397416591644,
-0.000009531160685583018,
-0.04215836152434349,
0.045543063431978226,
0.03585226461291313,
0.033799465745687485,
... |
<p>My question was motivated by my attempt to answer this <a href="https://physics.stackexchange.com/questions/119343/the-problem-in-srednikis-textbook-how-do-i-calculate-loop-corrections-for-ph">question</a>. Suppose we are given an action and we make a change of variables such that the theory is non-renormalizable. D... | g16394 | [
0.026502948254346848,
0.0022030749823898077,
-0.017513316124677658,
-0.05187058448791504,
0.010358219966292381,
0.001742078922688961,
0.02323366515338421,
0.03955917805433273,
-0.0008892555488273501,
-0.001831358764320612,
-0.0732281506061554,
0.019340619444847107,
-0.01750333048403263,
0.... |
<p>Which elementary particle has the greatest rest mass? (For the sake of this question I'll call a photon's rest mass 0, whether it is or isn't (actually, tell me if this is the right thing to do)).</p> | g16395 | [
0.04921179637312889,
-0.0036810331512242556,
0.03459563106298447,
-0.00567596685141325,
0.069135382771492,
0.009171487763524055,
-0.0009084274643100798,
-0.009815458208322525,
0.013023529201745987,
-0.03596709668636322,
0.023073216900229454,
-0.0224880650639534,
-0.09193017333745956,
-0.05... |
<p><strong>Simple Model w/o Doppler</strong></p>
<p>I have a speaker driven by an electrical signal. The pressure at the sampling point is some linear operator acting on the input signal: $L[ s(t)]$. Where $L$ combines the linear model representing the electrical components (LRC circuit) the mechanical components (m... | g16396 | [
0.008175627328455448,
-0.013280073180794716,
0.001126541057601571,
0.005731030832976103,
0.08940856158733368,
-0.021384770050644875,
0.04191626235842705,
0.008871080353856087,
-0.04390717297792435,
-0.014195268042385578,
-0.048287391662597656,
-0.035477906465530396,
0.03077644854784012,
0.... |
<p><img src="http://i.stack.imgur.com/GEnoN.gif" alt="enter image description here"></p>
<p>In an ideal circuit, How can there be a current b/w points a & b, when there is no potential difference and thus no electric field between a & b? If there is no current, then where does current across the resistor come ... | g16397 | [
0.025095704942941666,
-0.06872305274009705,
-0.01729593425989151,
-0.0029280318412929773,
0.08366893231868744,
0.05180991068482399,
0.031937677413225174,
0.025724636390805244,
-0.03992830589413643,
0.0074172369204461575,
0.0080568827688694,
0.05162007361650467,
-0.04111146926879883,
-0.006... |
<p>I have the following scenario: an iPhone is connected to a vertical rail (it's motion is restricted to the Y axis). Through mechanical means the phone is forced upwards and then allowed to return to rest. The distance varies (anywhere from 6" to 24"). The total time required for the full trip is roughly 1 - 2 second... | g16398 | [
0.04594944417476654,
0.009814507327973843,
-0.013133819214999676,
0.04472777619957924,
-0.0005066690500825644,
-0.012028944678604603,
0.08533060550689697,
-0.03238004073500633,
-0.05325094237923622,
-0.009403313510119915,
-0.03511489927768707,
0.01899891346693039,
0.01542336493730545,
-0.0... |
<p>This question came to my mind when I read on <a href="http://www.nasa.gov/mission_pages/swift/bursts/farthest_grb.html" rel="nofollow">NASA's website</a> that an explosion (gamma ray burst, GRB 080913) took place 12.8 billion light years away from us. How do they measure such large distances?</p> | g16399 | [
0.02465718239545822,
0.03596770390868187,
-0.009582186117768288,
0.0024943428579717875,
0.029109517112374306,
0.07948790490627289,
-0.05599169433116913,
0.030571257695555687,
-0.011117108166217804,
-0.05400008335709572,
-0.01972280442714691,
0.012617881409823895,
0.06431996077299118,
-0.03... |
<p>I am trying to write computer code which will find the energy and <a href="http://en.wikipedia.org/wiki/Density_functional_theory" rel="nofollow">density function</a> for an atom with $Z$ protons and $N$ electrons. I am working in 1D for simplicity and would like to make the overall code as simple as possible (I am ... | g16400 | [
-0.0016479382757097483,
-0.003306752070784569,
-0.021851330995559692,
-0.043388210237026215,
0.017343854531645775,
-0.04117972031235695,
-0.018229082226753235,
0.036593470722436905,
-0.017759699374437332,
0.05358434095978737,
0.0276394821703434,
-0.02207919955253601,
0.008584082126617432,
... |
<p>We know that gravity is a very weak force compared to electromagnetic forces and the nuclear forces. We know about the other forces because they're necessary to explain atoms, and we can detect gravity easily, because unlike the other forces it is always attractive, so the weak gravitational force from every particl... | g16401 | [
0.03144178166985512,
0.07913053780794144,
0.016403160989284515,
-0.0331573560833931,
0.05409660562872887,
0.05230409651994705,
-0.06045059114694595,
-0.02860964648425579,
-0.028063246980309486,
-0.05010303854942322,
-0.010166696272790432,
-0.007142390590161085,
0.0028596888296306133,
0.039... |
<p>My quantum mechanics textbook (Primer of Quantum Mechanics, by Marvin Chester) says that both the momentum space and the position space are basis spaces. It also says that the momentum space is quantized while the position space is a continuum. I have two questions:</p>
<ol>
<li><p>Is the fact that the momentum spa... | g16402 | [
0.03542311117053032,
-0.007625425700098276,
-0.004535395186394453,
-0.026793835684657097,
0.05440052971243858,
0.02447562664747238,
0.03103640489280224,
0.03538069874048233,
0.013133078813552856,
-0.007890479639172554,
-0.005364678334444761,
-0.03243623673915863,
-0.06136396527290344,
0.00... |
<p>Okay, this is nothing more than a thought experiment which popped into my head while driving home from work today. </p>
<p>Take the case of a single body orbiting another, larger body, as in a planet and a star. The planet is in a stable, non-decaying orbit.</p>
<p>Now assume that the mass of the planet was notice... | g16403 | [
0.031057680025696754,
0.05928877741098404,
0.025334300473332405,
0.0026672242674976587,
0.06485825777053833,
0.06365226954221725,
-0.03466939553618431,
0.033176664263010025,
-0.012672526761889458,
-0.07433780282735825,
0.014788421802222729,
-0.028075339272618294,
0.018402619287371635,
-0.0... |
<p>when we look at an object be it a metal or a non-metal are we looking at its electrons only, so then if all electrons are same then why do different chemicals or elements or objects have different color?
So basically are we detecting the energy emitted by the electrons only?</p> | g16404 | [
0.05269875004887581,
0.016463996842503548,
0.02401411347091198,
-0.007309391628950834,
0.08414919674396515,
0.011477644555270672,
-0.02336810529232025,
0.030452415347099304,
-0.0001623963180463761,
-0.023867439478635788,
0.03675461933016777,
0.09264031052589417,
0.0674269050359726,
0.01944... |
<p>How functionaly dense are <a href="http://en.wikipedia.org/wiki/Nebula" rel="nofollow">nebulae</a>? Are they so sparse they are only visible from an interstellar or intergalactic perspective or would you be unable to see your hand in one? </p>
<p>Do they vary widely in density, between nebulae or even within a sing... | g16405 | [
-0.060329094529151917,
0.04294072464108467,
-0.0021896485704928637,
-0.09424210339784622,
0.038983095437288284,
-0.043525636196136475,
-0.04401266947388649,
0.04561324045062065,
-0.01641884818673134,
-0.041113127022981644,
0.0498814694583416,
-0.004889628384262323,
0.034906525164842606,
-0... |
<p>As a solar system evolves the planets interact, and in trying to achieve a harmonious state some bodies are ejected. Space is big, but I have heard that some meteorites have been found with anomalous isotope ratios that could have come form beyond the solar system.</p>
<p>There must be a variety of bodies of differ... | g16406 | [
-0.013227774761617184,
0.06893642246723175,
-0.013707471080124378,
-0.029494106769561768,
-0.012352477759122849,
0.011725851334631443,
-0.05505506694316864,
-0.038037244230508804,
0.03236126899719238,
-0.03901083767414093,
0.015970958396792412,
0.01551269181072712,
0.05510276183485985,
-0.... |
<p>There are some planets that scientists speculate may be capable of supporting life. However, these planets are hundreds of light years away. How can we be sure they are still capable of supporting life, that they are still there, or even have life?</p> | g16407 | [
0.021258383989334106,
0.021632827818393707,
0.01091984286904335,
-0.028055496513843536,
0.019634444266557693,
0.06912001967430115,
-0.07963917404413223,
0.0052719018422067165,
0.03126997873187065,
-0.039092641323804855,
0.005541278515011072,
0.002164457691833377,
0.018468810245394707,
-0.0... |
<p>Where can I find a site that will give me an indication of coverage for the <a href="http://en.wikipedia.org/wiki/Solar_eclipse_of_November_25,_2011" rel="nofollow">November 25th 2011 partial solar eclipse</a> as viewed from <a href="http://en.wikipedia.org/wiki/Christchurch" rel="nofollow">Christchurch, New Zealand... | g16408 | [
-0.005977474618703127,
0.008249053731560707,
-0.011516265571117401,
-0.006900446023792028,
-0.05688989534974098,
0.0038441934157162905,
-0.0027976196724921465,
0.022604137659072876,
-0.004636002238839865,
-0.009239637292921543,
0.04863853380084038,
0.015463976189494133,
-0.006829986814409494... |
<p>In accelerators we shoot very high momentum particles at each other to probe their structure at very small length scales. Has that anything to do with the HUP that addresses the <em>spread</em> of momentum and space?</p>
<p>Related, when we accelerate a proton at exactly, say, 1 GeV, then we know exactly its moment... | g16409 | [
0.07996212691068649,
0.06018077954649925,
0.003628884209319949,
0.024761520326137543,
0.10692612826824188,
0.0575687475502491,
0.0016730421921238303,
0.061464134603738785,
-0.02572673186659813,
-0.0414348840713501,
0.017593521624803543,
0.0164590235799551,
-0.01205870509147644,
-0.00807725... |
<p>Since frames of reference are arbitrary, I can define a frame of reference that moves backwards with a speed greater than $c$, then any static object in that frame of reference is already traveling forwards faster than $c$!<br/><br/>
So what does "nothing can travel faster than light" exactly mean, and where does it... | g348 | [
0.0279717855155468,
0.026184754446148872,
0.0006022903835400939,
-0.005887899547815323,
0.08225806802511215,
-0.00787643063813448,
0.05377034470438957,
0.023775191977620125,
-0.07366744428873062,
-0.0671892762184143,
-0.003728745970875025,
0.0016892168205231428,
0.04053325206041336,
0.0067... |
<p>I am trying to solve a task in which I need to calculate the optimal angle($\alpha$) with which the projectile will land the furthest from a height ($h$), so what I basically have is the equations for the projectile's movement:</p>
<p>$$
x = v_0 \cos\alpha t
$$
$$
y = h + v_0\ \sin\alpha t - \frac{gt^2}{2}
$$
$$
t... | g16410 | [
0.03782850503921509,
-0.012637760490179062,
0.010378196835517883,
-0.0023809093981981277,
0.002399722347036004,
0.008778834715485573,
0.01859668456017971,
-0.009148500859737396,
-0.06606026738882065,
-0.016790645197033882,
-0.05392235144972801,
0.07637207955121994,
0.017739033326506615,
-0... |
<p>I'm doing a physics problem in which a marble spins around a spinning bowl and both have angular velocity $\omega$. It rotates with radius $r$ around the central axis and the hemispherical bowl has radius $R$. I've solved for the radius $r$ in terms of $\omega$:</p>
<p>$$r=\sqrt{R^2-\frac{g^2}{\omega^4}}$$</p>
<p>... | g16411 | [
0.035811930894851685,
0.07052694261074066,
-0.023735513910651207,
-0.046287912875413895,
0.07041972130537033,
0.03885457664728165,
0.10802433639764786,
-0.03618559241294861,
-0.012281064875423908,
0.009826558642089367,
-0.06528638303279877,
0.012800573371350765,
0.031735457479953766,
-0.04... |
<p>I am looking for a generic term for sets of atomic orbitals (viz. spherical harmonics) which are grouped by crystal symmetry. The most familiar examples would be $e_g$ and $t_{2g}$ (in cubic symmetry). So I would like to be able to say something like “$e_g$ and $t_{2g}$ are examples of …”</p>
<p>What comes to my ... | g16412 | [
-0.020628344267606735,
0.05902579799294472,
0.0013450069818645716,
-0.08288653939962387,
-0.0014335531741380692,
0.018443970009684563,
-0.0038185431621968746,
-0.026187801733613014,
-0.013886366039514542,
0.0315011702477932,
0.03406344726681709,
0.006250129081308842,
0.030283551663160324,
... |
<p>I want to solve 2d Poisson equation with this Boundary conditions below </p>
<p>$$u(-5,y) = 0 , \\
\frac{\partial u(x,y)}{ \partial x} = 0 \,\,{\rm at}\,\, x = -5\\
u(x,-5) = u(x,5)$$</p>
<p>Now my question is why one of the boundaries have defined both Neumann and Dirichlet? And what is the boundary condition on ... | g16413 | [
0.09265448898077011,
-0.02313334122300148,
-0.0022669322788715363,
-0.021617649123072624,
0.04680564999580383,
-0.004703426267951727,
0.03267643600702286,
-0.011446583084762096,
-0.06839659810066223,
-0.047844596207141876,
-0.06021561101078987,
0.03173183649778366,
-0.04029793292284012,
0.... |
<p>My question pertains to the concept of a constantly accelerating rocket as it approaches the speed of light. The scenario is as follows:</p>
<p><em>A rocket is constantly accelerating at 1g to reach Andromeda. Assume travel is in only one direction and no external forces act on the rocket e.g. gravity. It's just th... | g16414 | [
0.03700144588947296,
0.006116545293480158,
0.017475390806794167,
0.04493337869644165,
0.004369060508906841,
-0.01802285760641098,
0.017420655116438866,
0.06088221073150635,
-0.03528306260704994,
0.02083856612443924,
-0.003993327263742685,
0.024022679775953293,
0.027626708149909973,
0.03254... |
<p>Does all electrical insulator can be electrostatically charged, or insulator with only dielectric property can? Thank you.</p> | g16415 | [
0.020296387374401093,
0.004893297329545021,
0.023775948211550713,
0.047606460750103,
0.03020680695772171,
0.01522300485521555,
-0.03716816380620003,
0.00505393510684371,
0.00331122032366693,
0.0346410758793354,
-0.030447140336036682,
0.028982358053326607,
-0.019482335075736046,
-0.05135395... |
<p>In Landau and Lipshitz's introductory book on Quanum Mechanics, "Quantum Mechanics Non-Relativistic Theory, Third Edition: Volume 3", chapter XIV (page 433 in the edition on Amazon) is "Addition of Angular Momenta". Interestingly, the first page is footnoted to the effect that the theory covered only applies in the ... | g16416 | [
0.04522862285375595,
0.00844799168407917,
-0.01023452915251255,
-0.01903105527162552,
0.0817268118262291,
0.040251098573207855,
-0.000960739329457283,
0.015039068646728992,
0.020107069984078407,
-0.00645470293238759,
-0.0033545379992574453,
-0.027070021256804466,
-0.03592851012945175,
-0.0... |
<p>This <a href="http://physics.stackexchange.com/questions/3612/binary-black-hole-solution-of-general-relativity">question</a> on binary black hole solutions, led to me think about the similar question from the perspective of what we know about the Hydrogen atom.</p>
<p>Prior to quantum mechanics, it was not understo... | g16417 | [
0.0006455177790485322,
0.02172650396823883,
0.007694000378251076,
0.0044992100447416306,
0.0637684240937233,
0.006351584102958441,
-0.015002569183707237,
0.02552896738052368,
-0.04225383326411247,
-0.004218888934701681,
0.02901344932615757,
0.04912649095058441,
-0.015200579538941383,
0.017... |
<p>When light interacts with matter, it is abosrbed, reflected and transmitted. With repect to the UV-Vis range, electronic abosrptions occur, where if the incident photon mode matches the energy difference of electronic transitions in the atom, then the photon gets absorbed.
What is happening during transmission? Wha... | g16418 | [
0.01650644652545452,
0.011394990608096123,
0.004711812827736139,
0.028392478823661804,
0.06977255642414093,
0.037679169327020645,
-0.01636536978185177,
0.015050345100462437,
0.05216999351978302,
0.032580867409706116,
0.005498993210494518,
0.030396845191717148,
0.033144135028123856,
-0.0272... |
<p>What is the electrostatic potential due to a point charge in a five-dielectric medium with planar interfaces? Specifically, consider a system with planar interfaces, and the dielectric constants:
$$
\epsilon_1,\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ z<-a \\
\epsilon_2,\ \ \ -a<z<-b \\
\epsilon_3,\ \ \ \ \ \ -b<... | g16419 | [
0.05250915139913559,
0.013571388088166714,
-0.043604280799627304,
0.007092027924954891,
0.04593869671225548,
-0.0024370744358748198,
0.010851752944290638,
-0.018762696534395218,
-0.03764190897345543,
0.06393672525882721,
-0.0820261761546135,
-0.026324257254600525,
-0.008124844171106815,
-0... |
<p>There is a sphere with radius $R$ that carries a polarization
$$\vec P(\vec{r})=k\vec r$$</p>
<p>$\vec r$ is the vector from the center.</p>
<p>I found electric field the outside generated by the sphere is $\vec E=0$</p>
<p>Can you, please, explain it in physical terms?</p> | g16420 | [
0.011827139183878899,
0.0001178613820229657,
-0.0049907853826880455,
0.008068171329796314,
0.03295094519853592,
0.0401136614382267,
-0.019536269828677177,
0.00423500407487154,
0.013689043931663036,
0.019699038937687874,
-0.03583231940865517,
0.024722406640648842,
-0.0010217486415058374,
-0... |
<p>There seems to be an obvious contradiction between the predictions of the physics of black holes and the Big Rip, a predicted event about <a href="http://www.eurekalert.org/pub_releases/2012-07/sicp-dea071112.php">16.7 Gyr in the future</a> where local groups, galaxies, solar systems, planets, and even atoms will be... | g16421 | [
0.02541462890803814,
0.050915878266096115,
0.01565675251185894,
-0.04212851822376251,
0.005272998940199614,
-0.008457012474536896,
0.007192356511950493,
0.04402340203523636,
-0.002922849263995886,
-0.04698307812213898,
0.0467027984559536,
-0.02847432903945446,
-0.011121619492769241,
-0.040... |
<p>Some speculation here:<br>
<a href="http://www.youtube.com/watch?v=_NMqPT6oKJ8" rel="nofollow">http://www.youtube.com/watch?v=_NMqPT6oKJ8</a></p>
<p>Is there a possibility it would pass 'undetected' through your hand, or is it certain death?</p>
<p>Can you conclude it to be vital, or only loose your hand?</p>
<p>... | g372 | [
0.07778628915548325,
0.006009679287672043,
0.011232101358473301,
0.01646670326590538,
-0.01824558712542057,
0.02681354619562626,
0.004385555628687143,
0.07173280417919159,
0.025720015168190002,
-0.033339958637952805,
0.008395494893193245,
-0.008545720018446445,
-0.023943839594721794,
-0.04... |
<p>I have an idea that the law (since it's based on average energy, number of modes per volume, and a constant) would be shortened to something that would eliminate the summation terms in average energy.</p>
<p>My problem is I can't seem to make the law both frequency AND temperature dependent if I simplify that way.<... | g16422 | [
-0.021618051454424858,
-0.0012388022150844336,
-0.014830777421593666,
0.004353988915681839,
-0.013197685591876507,
-0.009102901443839073,
0.03740176185965538,
0.046904489398002625,
-0.037831779569387436,
0.0448165200650692,
-0.008485961705446243,
-0.03559853136539459,
-0.013647636398673058,
... |
<p>The Hamiltonian
\begin{equation}
H=J\sum_{i,j}\vec{n}_i\cdot\vec{n}_j
\end{equation}
is invariant under a global rotation $\vec{n}_i\rightarrow R\vec{n}_i$, where $\vec{n}$ is a $N$ component rotor with fixed length $|\vec{n}|=1$ and $R$ is the $N\times N$ rotational matrix. Since $R$ satisfies $R^{T}R=1$, the det... | g16423 | [
-0.003145970171317458,
-0.005296103656291962,
-0.007805318105965853,
0.024273216724395752,
-0.0004063652013428509,
0.002503558062016964,
0.1089048832654953,
-0.01615910418331623,
0.02123723365366459,
0.07613618671894073,
-0.008588237687945366,
-0.005091553553938866,
-0.042231447994709015,
... |
<p>There have been conducted many experiments in which light impulses traveled faster than light like the one in Princeton in 2000. This phenomenon has something to do with quantum entanglement. Does anyone know how it's possible and can give an explanation?</p> | g16424 | [
0.015186741016805172,
0.05372006446123123,
0.018463876098394394,
-0.009406661614775658,
0.06487755477428436,
0.02405405044555664,
0.04271644726395607,
0.057724662125110626,
-0.028059566393494606,
-0.028907988220453262,
-0.0007697007386013865,
-0.030521506443619728,
0.032859425991773605,
0.... |
<p>In a previous question <a href="http://physics.stackexchange.com/questions/55518/emergent-symmetries">Emergent symmetries</a> I asked, Prof.Luboš Motl said that emergent symmetries <strong>are never exact</strong>. But I wonder whether the following example is an counterexample that has <strong>exact</strong> emerg... | g16425 | [
-0.012518845498561859,
0.00045050791231915355,
0.008175254799425602,
0.008513003587722778,
0.02708200179040432,
-0.003508992027491331,
0.0454331710934639,
0.05772100016474724,
0.02715205028653145,
-0.007543469313532114,
-0.05068554729223251,
-0.06358093023300171,
0.012617676518857479,
0.03... |
<p>How long will a water drop exist until it evaporates based on ambient conditions? I am looking for a simple equation or table that would tell me how long a water drop may exist until it evaporates based on ambient conditions (RH, T etc.)</p> | g16426 | [
0.06353066861629486,
-0.001703789341263473,
-0.009907115250825882,
-0.02128671109676361,
-0.02208578772842884,
0.07455052435398102,
0.012852957472205162,
-0.016864754259586334,
-0.06653773784637451,
0.03208073601126671,
-0.02813650108873844,
0.05639702081680298,
0.045749232172966,
0.018521... |
<p>Let $\langle\Omega|$ be the ground state of an interacting theory, just as Peskin & Schroeder(PS) describes on page 82 and page 213. On page 213 PS do the following </p>
<p>$$\tag{1}\langle\Omega|\phi(x)|\lambda_{\vec{p}}\rangle = \langle\Omega|\exp(+\mathrm{i}Px)\phi(0)\exp(-\mathrm{i}Px)|\lambda_{\vec{p}}\ran... | g16427 | [
0.023906821385025978,
0.013315757736563683,
-0.01737084984779358,
-0.05591587349772453,
0.0362568162381649,
0.033031146973371506,
0.008917298167943954,
0.028051048517227173,
0.032175205647945404,
0.02075033262372017,
-0.020278047770261765,
-0.008245454169809818,
-0.0026950405444949865,
0.0... |
<p>Do Euler-Lagrange equations hold only for inertial systems? If yes, where is the point in the variational derivation from Hamilton's principle where we made that restriction? </p>
<p>My question arose because I was thinking how could you describe the motion of pendulum with an oscillating suspension point, somethin... | g16428 | [
0.07066019624471664,
0.03146324306726456,
0.01634940691292286,
-0.015346406027674675,
0.06913105398416519,
-0.013287559151649475,
0.05420607700943947,
-0.025643281638622284,
-0.0030545934569090605,
-0.017310719937086105,
-0.016916390508413315,
0.025596197694540024,
-0.02043934538960457,
0.... |
<p><strong>Problem</strong> Consider a sphere with radius $R$, and with a charge distribution $\rho(r)=\rho_0r$. Using Poisson's equation, calculate the electric potential inside and outside the sphere.</p>
<p><strong>Solution</strong> I don't know how to solve completely this problem. I understand that outside the sp... | g16429 | [
0.04237857088446617,
-0.01345541700720787,
-0.01924530416727066,
-0.03878018260002136,
0.009764055721461773,
0.0018515047850087285,
0.0021761409007012844,
0.015740398317575455,
-0.02707015536725521,
0.023670831695199013,
-0.05976317450404167,
0.01637294702231884,
-0.023608483374118805,
0.0... |
<p>Can unexposed PMMA be reused (successfully exposed) after development?</p>
<p>To clarify, <a href="http://en.wikipedia.org/wiki/Poly%28methyl_methacrylate%29" rel="nofollow">PMMA</a> is exposed using an electron beam in an SEM, and then the exposed areas are removed using a developer solution, because the exposed r... | g16430 | [
0.013021229766309261,
-0.06775940954685211,
0.032357119023799896,
-0.0526617169380188,
0.0033112261444330215,
-0.03266550600528717,
-0.026206398382782936,
0.050395458936691284,
0.0777539610862732,
0.015204242430627346,
-0.010349639691412449,
0.02600349299609661,
-0.009265545755624771,
0.03... |
<p>I'm reading this <a href="http://people.sissa.it/~bertmat/teaching.htm" rel="nofollow">note</a> in chapter 6 which discusses $ {\cal N} = 2 $ supermultiplets, though the discussion is quite general and applies to $ {\cal N} = 1 $ fields in the adjoint representation. I summarize the discussion given in the paper her... | g16431 | [
0.0408938005566597,
0.03405499830842018,
-0.027538999915122986,
-0.03599271923303604,
0.03571615740656853,
0.0023734732531011105,
0.04999854788184166,
0.03735865280032158,
-0.040031880140304565,
-0.0035249930806457996,
0.006650288123637438,
0.02116987854242325,
-0.020435849204659462,
0.050... |
<p>If you place a conductor beside an insulator, the insulator will become negatively charged and the conductor will become positively charged. Air is an insulator. So why don't all conductors placed in air automatically become positively charged and the air around it become negatively charged?</p>
<p>See, for example... | g16432 | [
0.04102272912859917,
0.0188828743994236,
-0.014187189750373363,
0.07279866188764572,
0.04999380558729172,
0.09007083624601364,
0.024186154827475548,
0.1145683228969574,
-0.04845820367336273,
-0.001883530872873962,
-0.0497208833694458,
0.03814976289868355,
-0.03785004839301109,
0.0382994301... |
<p>Is there a limit on how hot you can superheat water at 1 atm in a perfect container? What about in a microwave?</p> | g16433 | [
0.025611627846956253,
0.04247508570551872,
0.012145780958235264,
0.025516144931316376,
-0.01854136772453785,
-0.017540309578180313,
-0.03516706824302673,
0.009236367419362068,
-0.06485465914011002,
0.01950945146381855,
0.0005343076772987843,
0.017649298533797264,
-0.022848498076200485,
0.0... |
<p>My professor asked me (in my viva exam), <em>"If, in the Fraunhofer single slit diffraction experiment, if we have 2 slits instead of one (at very short distances), What would happen?"</em></p>
<p>I answered with "Young's double slit experiment intensity distribution". He said my answer was wrong. Out of curiosity,... | g16434 | [
0.05608776584267616,
0.007827558554708958,
-0.006191777531057596,
-0.014003741554915905,
-0.025276130065321922,
0.03928718715906143,
0.02251708321273327,
0.0721299946308136,
-0.006981410086154938,
-0.04946579039096832,
0.0021369680762290955,
0.04081737622618675,
-0.005388063844293356,
0.00... |
<p>Now that it's been freezing outside for the last few days, I experimented a bit with supercooling. I've left a bottle of clean water outside for a few hours, and behold, when I shook the bottle, the liquid began to freeze rapidly, as expected. </p>
<p>However, not all of the water froze, only about half of it. This... | g16435 | [
0.0016753809759393334,
0.021801548078656197,
0.0037855824921280146,
0.05050235241651535,
0.002156898844987154,
-0.0035737373400479555,
0.032846804708242416,
0.06269940733909607,
-0.0814933106303215,
0.025353191420435905,
-0.020306775346398354,
0.05406373366713524,
0.026761338114738464,
0.0... |
<h1>Short version</h1>
<p>After integrating over all possible outgoing angles, the total cross-section of coherent elastic scattering from a fixed target of characteristic length $L$ scales like $L^4$. Does this mean, given a beam of sufficiently small angular dispersion and detectors capable of sufficiently fine ang... | g16436 | [
0.017714839428663254,
0.00875040888786316,
0.015952255576848984,
-0.037529002875089645,
0.005577815230935812,
0.026296937838196754,
0.01692434400320053,
0.042741868644952774,
-0.01716768927872181,
-0.04313114285469055,
0.04181072860956192,
-0.009936128742992878,
0.02015066333115101,
-0.035... |
<p>and so if a proton is so larger than an electron doesn't that mean it has a shape? What would be the shape of a subatomic particle? are they spherical?</p> | g16437 | [
0.03913237899541855,
0.01765531860291958,
0.008534685708582401,
-0.007694226689636707,
0.05132513865828514,
0.03894442692399025,
-0.04322141036391258,
0.010882437229156494,
-0.019237158820033073,
-0.04178621247410774,
-0.02113202027976513,
0.020088985562324524,
0.02617632783949375,
-0.0242... |
<p>When we have a rope with one fixed end and we send a pulse through it, the reflected pulse is inverted. My question is as follows - is it correct to say that near the end (when the pulse hits the fixed end) the reflected-inverted pulse is superposing with the part of the pulse which didn't hit the end yet? In other ... | g16438 | [
0.03393270820379257,
-0.018095053732395172,
0.004156365990638733,
-0.04458453878760338,
0.07086427509784698,
0.03935869783163071,
0.04557979106903076,
0.059924349188804626,
-0.05543409287929535,
0.00024225986271630973,
-0.07128807157278061,
0.030419370159506798,
-0.02992408722639084,
-0.04... |
<p>I am wondering how to describe the collapse of a photon state when it is measured in the polarization degree of freedom (say by a filter which let pass just one particular polarisation).</p>
<p>Let the free photon be in the state $$a^{\dagger}_{f,H}+a^{\dagger}_{g,V}$$ (disregarding the normalisation) where $$a^{\d... | g16439 | [
-0.009214651770889759,
-0.010972161777317524,
-0.005986773408949375,
-0.008702412247657776,
0.030698686838150024,
-0.012275351211428642,
0.004072858951985836,
0.017347047105431557,
0.026741471141576767,
0.01421445794403553,
-0.016216572374105453,
0.0220530703663826,
0.03185958042740822,
0.... |
<p>How can we demonstrate <a href="http://en.wikipedia.org/wiki/Total_internal_reflection" rel="nofollow">total internal reflection</a> practically to explain it clearly?</p> | g16440 | [
-0.02071869932115078,
0.041900571435689926,
-0.015320820733904839,
-0.08138474822044373,
0.046266183257102966,
-0.02707827091217041,
0.07760847359895706,
0.0746270939707756,
-0.038339968770742416,
-0.018061241135001183,
-0.0229644738137722,
0.012371117249131203,
0.010427326895296574,
0.002... |
<p>A way some people explain (or try to explain) how gravity works is using space-time curvature: an object with high mass distorts the surrounding space-time plane like a bowling ball distorts a sheet of plastic and the surrounding objects are always trying to roll down to that other object.</p>
<p>However, this expl... | g13 | [
0.007896441966295242,
0.09253261983394623,
0.0018749027512967587,
-0.01798676699399948,
0.028587372973561287,
0.06336378306150436,
0.013570775277912617,
0.03027608059346676,
-0.07115718722343445,
-0.03292060270905495,
0.03232906758785248,
-0.035953931510448456,
0.08883457630872726,
0.03633... |
<p>In trying to understand diffraction, I keep coming across Huygen's principle as the why behind diffraction, and I think I understand the principle itself all right. However, I was hoping to find an explanation of why exactly Huygen's principle explains what happens for electromagnetic radiation. </p>
<p>I can visua... | g16441 | [
0.028616400435566902,
0.04327750205993652,
0.0026523657143115997,
-0.023240579292178154,
0.030803851783275604,
0.04148567467927933,
0.047632284462451935,
0.00801311619579792,
-0.01222213450819254,
-0.03801345080137253,
0.013642579317092896,
-0.004273559898138046,
0.016307992860674858,
-0.0... |
<p>In mathematical physics and other textbooks we find the <a href="http://en.wikipedia.org/wiki/Legendre_polynomials">Legendre polynomials</a> are solutions of Legendre's differential equations. But I didn't understand where we encounter Legendre's differential equations (physical example). What is the basic physical ... | g16442 | [
0.07092050462961197,
0.03843620419502258,
-0.0015244822716340423,
0.005756267812103033,
0.08952335268259048,
-0.0017540593398734927,
0.02689843438565731,
0.013936789706349373,
-0.06201278418302536,
0.01002860814332962,
0.0077750105410814285,
0.016850197687745094,
0.021230878308415413,
-0.0... |
<p>I assume -- and maybe wrong -- that lens flares, in photography, are caused by light getting "trapped" inside the curved lens and bouncing around (due to refraction and non-perfect total internal reflection) causing bright spots at periodic intervals, when they partially escape on the imaging side. This would give t... | g499 | [
-0.00020084422430954874,
0.0012989152455702424,
-0.008893129415810108,
0.02902155928313732,
0.05179222300648689,
-0.004439620766788721,
0.05306762456893921,
0.021466871723532677,
0.023646578192710876,
-0.06205195561051369,
-0.03611041605472565,
0.011459005065262318,
0.07950830459594727,
-0... |
<p>I want to understand where the matrix:</p>
<p>$$ \left|\psi(t)\right> = \binom{a(t)}{b(t)} = \begin{bmatrix}
cos(\Omega t/2)&-ie^{i\phi_L t}sin(\Omega t/2) \\
-ie^{-i\phi_L t}sin(\Omega t/2) & cos(\Omega t/2)
\end{bmatrix}\binom{a(0)}{b(0)}$$</p>
<p>comes from.</p>
<p>I've already derived
$$\dot{a}... | g16443 | [
0.014596762135624886,
-0.022904539480805397,
-0.01727891154587269,
-0.05745064839720726,
0.08334463834762573,
-0.023082483559846878,
0.05682728812098503,
0.019315101206302643,
0.0038938673678785563,
-0.018261468037962914,
0.004682982340455055,
0.06911610811948776,
0.01963953860104084,
-0.0... |
<p>Silly question ...
An antenna is necessary to receive a transmitted signal from atmosphere, or otherwise. The transmitted signal weakens as it travels through the atmosphere. When the signal encounters an antenna (subject to antenna gain) a corresponding signal is induced in the antenna. </p>
<p>Is the inducing sig... | g16444 | [
-0.030882179737091064,
-0.02074630744755268,
-0.011174315586686134,
-0.014066562056541443,
0.014261606149375439,
0.05178298056125641,
0.014684430323541164,
0.04215915501117706,
-0.028381869196891785,
-0.043143026530742645,
-0.09165386855602264,
0.07047941535711288,
-0.01889914646744728,
0.... |
<p>I've been asked to complete this chart and have never come across this symbol before, nor can I find anything about it on google:</p>
<p><a href="http://postimage.org/image/oe7hb9cy3/" rel="nofollow">http://postimage.org/image/oe7hb9cy3/</a></p>
<p>What does the y with the line over it represent?
And also, does th... | g16445 | [
0.00670164218172431,
0.03585345670580864,
-0.02511245757341385,
-0.044649600982666016,
0.016397831961512566,
-0.037671755999326706,
0.08280497044324875,
-0.02068166248500347,
-0.012163978070020676,
0.01415534783154726,
-0.02341083437204361,
-0.0007700921269133687,
0.05977289006114006,
-0.0... |
<p>I want to know what exactly is the <a href="http://www.google.com/search?as_epq=differential+mode+group+delay" rel="nofollow">differential mode group delay</a> in optical fibers, is it the same thing as <a href="http://en.wikipedia.org/wiki/Dispersion_%28optics%29" rel="nofollow">dispersion</a>?</p> | g16446 | [
-0.014709381386637688,
-0.0036408109590411186,
-0.021566124632954597,
-0.026079878211021423,
0.08438524603843689,
0.026610009372234344,
0.04854806512594223,
0.012200305238366127,
-0.04690341278910637,
-0.057970236986875534,
-0.00006408274202840403,
0.004649036563932896,
0.033025383949279785,... |
<p>I've just watched a Discovery Science program - Alien Encounters featuring SETI luminaries such as Jill Tarter, Frank Drake and Nick Sagan. A serious discussion on how to interpret ET messages coupled with a dramatised depiction of the social impact on Earth of an impending visit from ETs. My major point of confusio... | g16447 | [
-0.004401147831231356,
0.0719737634062767,
0.01056195329874754,
-0.0014218396972864866,
0.05281269922852516,
0.05191490426659584,
0.012557134963572025,
-0.044050153344869614,
-0.01854449324309826,
-0.018860381096601486,
0.10398069024085999,
0.05802471563220024,
0.07746022939682007,
-0.0000... |
<p>I have a system with energy spectrum which has two groups of $N$ degenerate levels (the gap between them is $E$). There are $N$ non-interacting fermions in the system. What is the occupation factor at $T\ll E$ for upper level in grand canonical?
I can compute the factor in canonical ensemble but in grand canonical t... | g16448 | [
-0.06253915280103683,
0.005752714816480875,
-0.0059937480837106705,
-0.08302221447229385,
0.04684131219983101,
0.049881454557180405,
0.03400278463959694,
0.042653366923332214,
-0.04150965064764023,
-0.0005075476947240531,
-0.030503137037158012,
0.05167309567332268,
-0.020041214302182198,
0... |
<p>Hard boson has strong repulsion with each other just like fermion. What is the differences between hard-cord boson and fermion. Which materials are hard-core bosons?</p> | g16449 | [
0.02770131826400757,
0.02939535863697529,
0.05035052075982094,
-0.0214223675429821,
0.04588838666677475,
0.002056782366707921,
-0.08073943853378296,
-0.03425735607743263,
0.03548083081841469,
-0.015124301426112652,
-0.03895306959748268,
0.020941177383065224,
-0.0522962287068367,
-0.0294283... |
<p>Objects floating on the surface of calm water seem to be attracted to one another and tend to come together in a drift. Is this attraction like gravity?</p> | g500 | [
0.029173366725444794,
0.008333966135978699,
0.0028223469853401184,
-0.01966671086847782,
0.04965492710471153,
0.09487217664718628,
0.061599571257829666,
-0.03184483200311661,
-0.054921749979257584,
-0.08059749007225037,
0.021958453580737114,
-0.011815334670245647,
0.019985094666481018,
0.0... |
<p>Why do people transport mirrors in inclined position? I frequently find people carrying mirrors in slant position on mini trucks.I guess it has some advantage of carrying them without breaking,and I am now so curious to know the reason behind it</p>
<p><img src="http://i.stack.imgur.com/J1S63.jpg" alt="Either sides... | g16450 | [
0.03012015111744404,
0.01344170793890953,
0.019353799521923065,
-0.03554055839776993,
0.01165515836328268,
0.02502996288239956,
0.026205342262983322,
0.005630787927657366,
-0.053946081548929214,
0.030596913769841194,
-0.018377337604761124,
-0.04291784018278122,
0.0029445330146700144,
0.016... |
<p>I was wondering if anyone could give a simple explanation of how light interacts with matter. From what I have read in QED, electrons will repel each other because of their ability to emit and absorb photons. However, I do not observe any <em>visible</em> light between objects around me, repelling each other when... | g16451 | [
0.01752701960504055,
0.05144333466887474,
-0.012644683010876179,
-0.026491399854421616,
0.04936181381344795,
0.0370585136115551,
0.035011082887649536,
0.012733981013298035,
-0.002115302486345172,
-0.03173553943634033,
0.05193336680531502,
0.016816016286611557,
0.06384718418121338,
0.009936... |
<blockquote>
<p>A particle is bound by</p>
<p>$$V(x) = \begin{cases}\infty,& x <0 \\ \frac{-32\hbar^2}{ma}, & x\le a \\ 0, & x \le a\end{cases}$$</p>
<p>a) how many states are there?</p>
</blockquote>
<p>i'm attempting to solve this via raising/lowering operators,
by taking $E_n = \langle ... | g16452 | [
-0.009632768109440804,
0.03105451911687851,
-0.02107097953557968,
-0.021185755729675293,
0.03489375114440918,
-0.013409174047410488,
0.03395676985383034,
0.04357506334781647,
0.0033528939820826054,
0.04140285402536392,
-0.04967297613620758,
0.032109010964632034,
-0.011045980267226696,
0.02... |
<p>I have got a quantum conservative system whose Hamiltonian is $H$. I consider an selfandjoint operator $O$ whose eigenvalues and eigenvectors are: $$O|\psi _{n}\rangle = \lambda _{n}|\psi _{n}\rangle$$</p>
<p>At initial time, the system is at the state $|\psi_{i}\rangle$. At time $t= \delta t$, I measure with the ... | g16453 | [
-0.00889806542545557,
-0.017317792400717735,
-0.01184811070561409,
0.00540695246309042,
0.029217571020126343,
0.0066657946445047855,
0.018396271392703056,
-0.006782752461731434,
-0.007545195985585451,
-0.0015758242225274444,
0.04035641625523567,
0.011269201524555683,
-0.013029319234192371,
... |
<p>This is a work-related question. A warm steel torus of a given diameter & thickness is left in a room held at a controlled temperature, how long does it take to reach equilibrium? Assume the air is circulating so that the torus doesn't create a warm spot. Of course it never <em>quite</em> gets there but this is ... | g16454 | [
0.0629107654094696,
0.015050580725073814,
0.005677467677742243,
-0.008035420440137386,
0.020227450877428055,
-0.006154427770525217,
0.09406320005655289,
-0.0005175399710424244,
-0.03584004566073418,
0.022778650745749474,
-0.016134047880768776,
0.03815150260925293,
-0.0064164879731833935,
-... |
<p>If I've understood correctly, the heavier elements needed for terrestrial planets such as iron can only form in supernova.</p>
<p>If that is indeed true, how long since the beginning of the universe would it take to create the first non gaseous planets? Is earth in anyway an "early" terrestrial planet?</p> | g16455 | [
0.022446440532803535,
0.051009077578783035,
0.006883850786834955,
0.011299856007099152,
0.05660591274499893,
0.07968783378601074,
-0.02862810716032982,
0.004104972817003727,
-0.03437137231230736,
-0.08195025473833084,
-0.06859652698040009,
-0.005425131414085627,
-0.004317272454500198,
-0.0... |
<p>Where is the way on a <a href="http://en.wikipedia.org/wiki/Rotating_black_hole" rel="nofollow">rotating</a> black <a href="http://en.wikipedia.org/wiki/Kerr_metric" rel="nofollow">hole</a> to another Universe? Where and how should it be entered by to get away from here?</p> | g16456 | [
-0.024507515132427216,
0.0035461450461298227,
-0.017949003726243973,
-0.035422176122665405,
0.03834789991378784,
0.0166326891630888,
0.06436264514923096,
0.0012169328983873129,
-0.041409797966480255,
-0.03248189017176628,
0.02922675386071205,
0.009800322353839874,
0.07148629426956177,
-0.0... |
<p>Let us consider two different scalar fields $\phi$ and $\chi$. The commutation relations for the creation and annihilation operators of the scalar field $\phi$ are given by
$$ [a(\textbf{k}), a(\textbf{k}') ]= 0 $$
$$ [a^\dagger(\textbf{k}), a^\dagger(\textbf{k}') ]= 0 $$
$$ [a(\textbf{k}), a^\dagger(\textbf{k}') ]=... | g16457 | [
0.01466814149171114,
-0.018110282719135284,
0.0012446665205061436,
0.03880005702376366,
0.09123916178941727,
-0.010010129772126675,
-0.014782366342842579,
0.0010186298750340939,
-0.02262899838387966,
0.045581672340631485,
-0.04461599886417389,
0.020563466474413872,
-0.016705352813005447,
-... |
<p>I am currently studying <a href="http://arxiv.org/abs/1309.2557" rel="nofollow">lecture notes by Akhmedov on interacting scalar field theory in de Sitter space</a>. In these notes, he considers a scalar field theory of the form
$$\mathcal{L}=\partial_\mu\phi_1\partial^\mu\phi_1+m^2\phi_1^2+\frac{\lambda}{3!}\phi^3_... | g16458 | [
-0.0015359208919107914,
-0.013146677985787392,
-0.035745132714509964,
-0.030006591230630875,
0.01545808557420969,
-0.022194618359208107,
0.08141903579235077,
-0.02750503085553646,
-0.0005017055082134902,
0.01733591966331005,
-0.00002237433182017412,
0.05614157021045685,
-0.02830982208251953,... |
<p>Every piece of knowledge in science has a beginning lying in someone's experiment. I would like to know which experiment gave scientists the reason to believe nuclear fission/fusion existed and was instrumental in the development of the field of nuclear energy. </p>
<p>I would also accept a thought experiment as an... | g16459 | [
0.07962358742952347,
0.033692795783281326,
0.027775438502430916,
0.029092155396938324,
0.05204236879944801,
-0.011374182067811489,
-0.024846993386745453,
0.0654241144657135,
-0.008654462173581123,
-0.0638195276260376,
0.009575474075973034,
-0.001441326574422419,
-0.031406305730342865,
0.04... |
<p>What is the most distant object from the earth that a spacecraft visited has visited so far? What was the mission and when did it happen?</p> | g16460 | [
-0.003632946638390422,
0.03875206410884857,
0.008421414531767368,
-0.016106177121400833,
-0.020202938467264175,
-0.00041198826511390507,
-0.019093342125415802,
-0.025219451636075974,
-0.002654906827956438,
-0.04628680646419525,
0.033785380423069,
0.05563482642173767,
0.04710272699594498,
-... |
<p>I've heard that using a refractor is better than a reflector when it comes to planets to best reproduce their colors. But perhaps other factors can weight in too? For example, do you want a slow or fast f-stop to get the best view of a planet? What about eye-pieces, what style of eyepiece construction will give t... | g16461 | [
0.03178194537758827,
0.05676797032356262,
0.002553132362663746,
-0.007108630612492561,
0.036121465265750885,
-0.02204018644988537,
-0.0014588527847081423,
-0.0035571011248975992,
-0.005819644778966904,
-0.023398255929350853,
0.12072190642356873,
0.008277824148535728,
0.03425523638725281,
0... |
<p>What is the difference between the "affine connection" (S. Weinberg, <em>Cosmology</em>) and "Christoffel symbols?"</p> | g16462 | [
0.0069335768930613995,
0.017037929967045784,
0.002170471241697669,
-0.024844881147146225,
-0.02979179285466671,
0.012522079050540924,
0.019738800823688507,
-0.07309406250715256,
-0.02902427315711975,
-0.011200507171452045,
0.018907278776168823,
-0.012507068924605846,
0.031763043254613876,
... |
<p><strong>The problem statement:</strong> </p>
<blockquote>
<p>Two protons with kinetic energies $W_{k1}=4GeV$ and $W_{k2}=2GeV$
colide and form new particles. What is the mass of newly born
particles? There are as many as possible new particles.</p>
</blockquote>
<p>Relevant equations here are:
\begin{align}
... | g16463 | [
0.026036221534013748,
-0.025171803310513496,
0.006597545463591814,
0.014012346975505352,
0.047871701419353485,
0.043524809181690216,
-0.025250043720006943,
0.01468710508197546,
-0.05722959339618683,
0.03741506114602089,
-0.0232527032494545,
0.03415347635746002,
0.0011387509293854237,
0.039... |
<p>My first question on Stackexchange (if it is formatted wrong or something please tell me so I know in future) - here it is:</p>
<p><strong>Given an unstable nucleus (exactly which nucleus is not particularly pertinent) - what decides <em>precisely</em> when it will decay?</strong></p>
<p>I am somewhat familiar wit... | g16464 | [
0.0033437185920774937,
0.04383876547217369,
0.011976351961493492,
-0.016234712675213814,
0.061556410044431686,
0.02485198900103569,
-0.03243059292435646,
0.04186004027724266,
-0.031124960631132126,
-0.06850053369998932,
-0.05846603587269783,
0.05263889208436012,
0.008386851288378239,
-0.00... |
<p>Principle difference between Linear and Non-Linear Magneto-optical effects and how they affect the property of light passing through a Vapor medium.</p> | g16465 | [
-0.031873926520347595,
-0.013253292068839073,
0.0067129433155059814,
0.029661770910024643,
-0.01323793362826109,
0.0032806042581796646,
0.014665335416793823,
0.002771802479401231,
-0.0069012632593512535,
0.03149913251399994,
0.03993701562285423,
0.013062921352684498,
-0.006887116003781557,
... |
<p>I get confused about when there should be a negative sign in certain equations or not. I will give three short examples (that I will make long with explanation) that show my confusion.</p>
<p>Example 1: Rockets.
Consider a rocket of mass $m$ traveling in the positive x direction with velocity $v$. The ejected fuel ... | g16466 | [
0.044741373509168625,
-0.042043931782245636,
0.0035570210311561823,
0.006420841906219721,
0.0517246350646019,
0.010042482055723667,
0.020348045974969864,
-0.03079836070537567,
-0.07614711672067642,
-0.01506450492888689,
0.03006584942340851,
0.009210561402142048,
0.03586844354867935,
-0.005... |
<p>Suppose an incident light from vacuum ($n_1=1.0$) into some media ($n_2=n_1+\mu\; x^2$) as in the figure below.</p>
<p>How to calculate the refracted light path curve in closed form?</p>
<p><img src="http://i.stack.imgur.com/YLMUt.png" alt="enter image description here"></p>
<p><strong>Update:</strong></p>
<p>Tr... | g16467 | [
0.03685350343585014,
-0.05491842329502106,
-0.006836672313511372,
0.030383620411157608,
0.024761056527495384,
0.0017643709434196353,
0.024961447343230247,
-0.008860193192958832,
0.012146227061748505,
-0.01766088232398033,
0.04326031357049942,
0.033958952873945236,
0.022605177015066147,
0.0... |
<p>Like could maybe fluctuate the space some how and make the virtual paricles turn into normal matter</p> | g16468 | [
0.01026219129562378,
0.02481946349143982,
-0.005159405525773764,
-0.04279690980911255,
0.031339604407548904,
-0.005116887390613556,
-0.01970941200852394,
0.013059360906481743,
0.01419609971344471,
-0.041050832718610764,
0.045952390879392624,
0.010689510963857174,
0.01909094676375389,
0.023... |
<p>Why does resonance occur in a mass-spring system when the natural frequency = the driving frequency. I think it is because the driving force is always contributing to the kinetic energy of the system rather then acting against it i.e. the driving force is in phase with the velocity of the system, or is there another... | g16469 | [
0.05064433068037033,
0.05017513409256935,
0.012854080647230148,
0.061550870537757874,
0.04966529831290245,
0.02850000187754631,
-0.009054576978087425,
0.019466670230031013,
-0.04743624106049538,
-0.03741493448615074,
0.014212045818567276,
-0.02063218504190445,
-0.003983062691986561,
0.0162... |
<p>The refractive index $n$ of a fibre is calculated as;
$$
n = c_0/c_m
$$</p>
<p>Where $c_0\approx 300000km/s$ is the speed of light in a vacuum, and $c_m$ is the speed of light in the fibre in question. How can I calculate the speed of light in a fibre?</p>
<p>I am a complete physics novice so answers need to be in... | g16470 | [
0.006950239650905132,
-0.024917127564549446,
-0.0006710056914016604,
-0.002743468852713704,
-0.0005268134991638362,
-0.03822671249508858,
-0.003176880767568946,
0.024519173428416252,
-0.017575621604919434,
0.017947793006896973,
0.011225512251257896,
0.04893479123711586,
0.011573725380003452,... |
<p>Assuming I shoot a beam of light to an electron, the electron will take the energy and reemit EMR at all direction randomly? If it will, is it happening at the same time?</p> | g16471 | [
0.002176760695874691,
-0.029048798605799675,
-0.029361391440033913,
0.07280196249485016,
0.055363401770591736,
0.0019272741628810763,
-0.04712608829140663,
0.020649123936891556,
0.005370247643440962,
-0.0002959472476504743,
-0.0301650483161211,
0.0448102243244648,
0.007941829971969128,
0.0... |
<p>First, I am not a native English-speaking student so I am not good at physics definitions in English. I participated in the MIT e-learning course on classical physics. The 1st lesson is about 3 fundamental physical quantities (time, length and mass). </p>
<blockquote>
<p>It mentions dimensional units/quantity and... | g16472 | [
0.0064616454765200615,
0.0514034777879715,
0.002654565963894129,
-0.018523957580327988,
0.04985879734158516,
0.05123068392276764,
-0.022557830438017845,
0.05525319278240204,
-0.035713713616132736,
-0.029890945181250572,
-0.00454855989664793,
-0.012686639092862606,
0.056884776800870895,
0.0... |
<p>What's the relation of earth's magnetic equator with satellite launching? How does the nearness of a rocket launching station to the earth's magnetic equator <a href="http://en.wikipedia.org/wiki/Thumba_Equatorial_Rocket_Launching_Station" rel="nofollow">make it an ideal location for scientists to conduct atmospheri... | g16473 | [
-0.03700850531458855,
0.023349635303020477,
0.0014511498156934977,
-0.03269244357943535,
0.008132269605994225,
0.022679882124066353,
-0.0187455415725708,
0.03084181435406208,
-0.0476674810051918,
0.016223013401031494,
0.020574502646923065,
0.019124632701277733,
0.03664040565490723,
0.00643... |
<p>Can superluminal travel or communication be possible without leading to the possibility of closed timelike curves (CTCs) and causality violations?</p>
<p>I have seen conflicting opinions regarding this issue, and whether all possible methods of superluminal travel (e.g. wormholes, Kraskinov tubes, and warp drives l... | g16474 | [
0.048908717930316925,
0.024323690682649612,
0.017633330076932907,
-0.017722170799970627,
0.011059591546654701,
0.02290511131286621,
0.011377612128853798,
0.017333216965198517,
-0.024720676243305206,
-0.016207575798034668,
0.05263391137123108,
-0.025996021926403046,
0.04019158333539963,
0.0... |
<p>If I have a container that is full of water and I attempt to freeze the water by freezing the container, what would happen if the container is strong enough to prevent the water expansion? Could the water be in liquid state even though it is at or below freezing point?</p>
<p>This is probably a daft question but it... | g477 | [
0.022911500185728073,
0.047738898545503616,
0.04343429207801819,
0.05279669165611267,
-0.06485013663768768,
0.02691730484366417,
0.0029036158230155706,
-0.009979688562452793,
-0.04082910716533661,
-0.020276563242077827,
0.005559258162975311,
-0.00156079709995538,
-0.01061124075204134,
-0.0... |
<p>When the direction of current is reversed, the polarity of an electromagnet should be reversed. I am trying to understand why this did not happen in an experiment I conducted today.</p>
<p>An electromagnet was connected to a 12v battery and I verified that it was working.
I then touched the electromagnet to a stron... | g16475 | [
0.014304217882454395,
-0.01798631250858307,
-0.0060931723564863205,
-0.015148845501244068,
0.05698423832654953,
0.04321334511041641,
-0.009938565082848072,
0.06540898978710175,
-0.012707429006695747,
0.014003336429595947,
0.020310932770371437,
0.025760669261217117,
-0.06371703743934631,
-0... |
<p>From my recent experience teaching high school students I've found that they are taught that the strong force between nucleons is mediated by virtual-pion exchange, whereas between quarks it's gluons. They are not, however, taught anything about colour or quark-confinement.</p>
<p>At a more sophisticated level of p... | g1010 | [
0.06018012762069702,
0.03798869252204895,
0.011217967607080936,
-0.09936290234327316,
0.09340071678161621,
0.015803704038262367,
-0.026593437418341637,
-0.04696236550807953,
0.01795027032494545,
-0.02887323498725891,
0.06307096779346466,
-0.006742896977812052,
-0.014943632297217846,
-0.055... |
<p>Do the protons inside the nucleus repel each other by the electrostatic force? If they do, why doesn't the repulsion drive the protons apart so that the nuclei get disintegrated?</p> | g425 | [
0.02667202800512314,
0.056667715311050415,
0.035242870450019836,
-0.035402942448854446,
0.11720235645771027,
0.010629137977957726,
-0.05943003296852112,
0.07990926504135132,
-0.04178463667631149,
-0.04656176269054413,
-0.019923949614167213,
-0.03772053122520447,
-0.04684469848871231,
-0.04... |
<p>An incident unpolarised light beam of intensity $I_{0}$ strikes glass plate B at Brewster's Angle. The reflected light travels vertically and strikes a second glass plate A, again at Brewster's Angle. (We ignore the light transmitted by the glass plates.) Plate A is then rotated about the z-axis as shown. Briefly ex... | g16476 | [
0.01686929352581501,
0.027253713458776474,
0.009649050422012806,
0.004189962055534124,
0.03424930199980736,
-0.013607420027256012,
0.0618918240070343,
0.03114006295800209,
0.0015121803153306246,
-0.004436205141246319,
-0.00946937408298254,
0.06832516193389893,
-0.04130477085709572,
-0.0386... |
<p>For an isotropic solid, Poisson's ratio can be expressed in terms of stiffness constants as:</p>
<p>$$\sigma = \frac{c_{11} - 2c_{44}}{2c_{11} - 2c_{44}}$$</p>
<p>Alternatively we may express Poisson's ratio in terms of the Lamé constants $\lambda$, $\mu$ where $\lambda = c_{12}$ and $\mu = c_{44}$. For an isotro... | g16477 | [
0.028934204950928688,
0.0015315439086407423,
-0.017930157482624054,
-0.08545365929603577,
0.04856159910559654,
-0.032520193606615067,
0.00876021757721901,
-0.011814134195446968,
-0.057482462376356125,
0.012752162292599678,
-0.0627996101975441,
0.04890279844403267,
-0.07126031816005707,
0.0... |
<p>If electric field is not present does that mean that charges achieve condition of electrostatics I.e, charges are stationary ?
But we say that stationary charge can produce electric field.
I read this statement one a page (link given below)
"Now if there's any $\vec E$ inside the conductor , we can surely say the... | g16478 | [
0.043778952211141586,
0.004455109592527151,
0.0018826669547706842,
-0.032175902277231216,
0.08957202732563019,
0.06541389226913452,
0.01555947307497263,
-0.01949983276426792,
-0.04235752299427986,
-0.000595801800955087,
-0.060720354318618774,
0.0028884559869766235,
-0.06343432515859604,
-0... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.