question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<ol>
<li><p>What differences between <a href="http://en.wikipedia.org/wiki/Mass#Gravitational_mass" rel="nofollow">gravitational mass</a> and <a href="http://en.wikipedia.org/wiki/Mass#Inertial_mass" rel="nofollow">inertial mass</a>? I cannot tell the differences between them. </p></li>
<li><p>In history, which concept... | g88 | [
0.051153503358364105,
0.020643992349505424,
-0.0037383954040706158,
-0.029835285618901253,
0.07406757771968842,
0.014891552738845348,
0.046840064227581024,
-0.0262595284730196,
-0.08667580783367157,
-0.023692365735769272,
0.005626427009701729,
-0.01079748198390007,
0.03816593810915947,
0.0... |
<p>Physicists in Europe said that only after combining data collected at a laboratory in Switzerland with data collected at a laboratory in the U.S, were they finally able to announce the discovery of a new sub-atomic particle.
Why did the physicists need so many measurements of the particle's mass to have confidence tha... | g18395 | [
0.04368641600012779,
0.0801587924361229,
-0.00846302229911089,
-0.014053354039788246,
0.0012738346122205257,
0.05425990745425224,
0.026626240462064743,
0.02973703294992447,
-0.05417507514357567,
-0.03933434933423996,
-0.0671076849102974,
-0.011654496192932129,
0.04981408268213272,
0.026553... |
<p>Jackiw and Rossi had a classic paper <a href="http://adsabs.harvard.edu/abs/1981NuPhB.190..681J" rel="nofollow">Zero modes of the vortex-fermion system (1981)</a>. In that nice-written paper, they found <a href="http://physics.stackexchange.com/questions/74081/zero-modes-zero-eigenvalue-modes-zero-energy-modes">ferm... | g18396 | [
-0.012311801314353943,
-0.0004901558859273791,
0.00980997271835804,
-0.027218135073781013,
0.007709290832281113,
0.009710430167615414,
0.05912923440337181,
0.03151003271341324,
0.03739209845662117,
-0.03109223209321499,
-0.05720949545502663,
-0.02420622669160366,
0.003308280138298869,
0.09... |
<p>In a scientific article, should I write "3m", "3 m", "3 meters", or "3 [meters]" ? </p> | g18397 | [
0.06797931343317032,
0.014189416542649269,
-0.018004314973950386,
0.019069332629442215,
0.03935588523745537,
-0.0024805201683193445,
-0.010225392878055573,
-0.018346522003412247,
-0.06317061930894852,
0.04631418362259865,
0.02410036325454712,
-0.02678592875599861,
-0.00797249935567379,
-0.... |
<p>Basically, how long does it take for electricity to determine there is a closed circuit and how does it know that the circuit exists? I'm curious to know how it knows there is a closed circuit at any length</p>
<p><strong>Edit:</strong></p>
<p>For clarification of the thought experiment, picture an electrical sour... | g18398 | [
0.04986165091395378,
-0.004946587141603231,
-0.007523646112531424,
-0.013883333653211594,
0.02635485678911209,
-0.016501320526003838,
0.03996987268328667,
0.0497376024723053,
-0.018885508179664612,
-0.014053918421268463,
-0.042458198964595795,
0.039334721863269806,
-0.0059336647391319275,
... |
<p>EDIT: As some confusion has appeared, I want to make another clear question. If gravitational energy is meaningless in general relativity (since it is the geometry), how can one come up with the graviton, the quanta of the gravitational field? </p>
<p>I would like to understand the concept of gravitation's energy (... | g18399 | [
0.00014399034262169152,
0.05538612976670265,
-0.01792275346815586,
-0.03397555276751518,
0.05474546179175377,
0.02248845435678959,
0.0038666583131998777,
0.00595519645139575,
-0.07025020569562912,
-0.027257032692432404,
0.0533868633210659,
-0.021500885486602783,
0.034018345177173615,
-0.09... |
<p>Non-physicist question:</p>
<p>Suppose two particles A and B are entangled and A collides with another particle. What happens to B?</p> | g18400 | [
0.04888123273849487,
0.035475850105285645,
0.024762211367487907,
-0.018542859703302383,
0.059815652668476105,
0.03834672272205353,
-0.060648005455732346,
0.013302601873874664,
0.0048241144977509975,
-0.008348197676241398,
-0.02741861157119274,
0.03800180181860924,
-0.016294674947857857,
-0... |
<p>What does the formula $$ {\bf F} ~=~ \frac{\mathrm{d}W}{\mathrm{d}{\bf x}}$$ actually mean? Here $\mathrm{d}W$ is the work done in a small period, ${\bf F}$ is the force and $\mathrm{d}{\bf x}$ is a symbol for arbitrary displacement. </p>
<p>How and where do we use this formula? Suppose a body moves in the path of ... | g18401 | [
0.03937183693051338,
0.01702450029551983,
-0.03599204495549202,
0.017731284722685814,
0.013942904770374298,
0.008343197405338287,
0.06756311655044556,
-0.009894980117678642,
-0.04399018734693527,
-0.10376442968845367,
0.0029800233896821737,
0.0006839645211584866,
0.044965509325265884,
-0.0... |
<p>What is entropy of the universe? What is the change in entropy of our universe? Is this change increases or decreases? If the entropy of universe keeps on increasing then what are the consequences? Is there any limiting factor to this increase? One practical application of entropy where it is applied in day to day l... | g568 | [
-0.057901155203580856,
-0.020574694499373436,
-0.003110830904915929,
-0.05078212916851044,
-0.026572279632091522,
-0.004863361828029156,
0.007316387724131346,
0.01873667910695076,
-0.005605374928563833,
-0.030607376247644424,
0.008374352939426899,
-0.03392713516950607,
0.03162744268774986,
... |
<p>Why can't photons have a mass? Could you explain this to me in a short and mathematical way?</p> | g180 | [
-0.005211516283452511,
0.05139141157269478,
0.005627492908388376,
0.029963912442326546,
0.02682088501751423,
0.03516264632344246,
0.020192811265587807,
0.0278128981590271,
-0.04351469501852989,
-0.04483552277088165,
-0.0026189005002379417,
-0.012053004465997219,
-0.006632803473621607,
0.00... |
<p>This question has several parts. </p>
<ol>
<li>How does modern science catch free neutrons that are just floating around?</li>
<li>Is there anyway to "pull" a neutron off <em>any</em> atom that does not involve our current nuclear reactors? </li>
</ol>
<p>They're not very controlled with tons of other forms of rad... | g18402 | [
-0.04409816116094589,
0.04264238849282265,
0.012270636856555939,
-0.0240563303232193,
0.03060968406498432,
0.019182724878191948,
-0.024434903636574745,
0.017463473603129387,
0.018810277804732323,
-0.0629977360367775,
0.007157721556723118,
0.0025115141179412603,
0.03924001380801201,
-0.0009... |
<p>Just got introduced to Hooke's law</p>
<blockquote>
<p><em>Simple Q: Three light springs, each of natural length l and with spring constant k, are arranged vertically between two points a distance 3l apart. One end of the first spring is fixed to a point on the ceiling. A weight of mass m is connected between the... | g18403 | [
0.0393606573343277,
0.018225137144327164,
0.006348339840769768,
0.026632733643054962,
0.044407010078430176,
0.02155529148876667,
0.020693644881248474,
-0.006032813340425491,
-0.08849085122346878,
-0.01785837672650814,
-0.07747847586870193,
-0.00014901311078574508,
-0.00720321387052536,
-0.... |
<p>I'm trying to find solutions to a harmonic oscillator that sits within an infinite square well. I haven't spent too much time yet, and I've had no success so far. I'm wondering how possible or complex an analytic solution would be? </p>
<p>The potential of a simple harmonic oscillator is:
$$V_1(x)=1/2 m \omega_0^2 ... | g18404 | [
-0.02424665167927742,
0.01103950571268797,
0.002821287838742137,
-0.07072754949331284,
-0.02331806719303131,
-0.03662744164466858,
0.007773985154926777,
0.06671496480703354,
0.02980090118944645,
0.01748056150972843,
0.0011042668484151363,
-0.06486683338880539,
0.00762665830552578,
0.065670... |
<p>When, say $\text{N}_2$, is in the wild, it regularly collides with other $\text{N}_2$.</p>
<p>I assume these collisions happen as, having become sufficiently close, the atomic electrons are repelled from the other molecule's electrons, setting up two dipoles (whose dipole moments are in opposite directions, so repe... | g18405 | [
-0.020952653139829636,
0.02594061754643917,
-0.030632779002189636,
-0.00413649994879961,
0.03769883140921593,
0.0110062500461936,
-0.016405053436756134,
0.01638038270175457,
-0.03676086291670799,
0.01617867685854435,
-0.002075765747576952,
-0.00277011189609766,
0.02843545563519001,
-0.0526... |
<p><a href="http://en.wikipedia.org/wiki/Nordstr%C3%B6m%27s_theory_of_gravitation" rel="nofollow">Nordstrom's theory</a> of a particle moving in the presence of a scalar field $\varphi (x)$ is given by
$$
S = -m\int e^{\varphi (x)}\sqrt{\eta_{\alpha \beta}\frac{dx^{\alpha}}{d \lambda}\frac{dx^{\beta}}{d \lambda}}d\lamb... | g18406 | [
0.02935204841196537,
0.011215743608772755,
-0.0416739284992218,
-0.06297846883535385,
0.0926675796508789,
-0.00993087887763977,
0.04052896797657013,
-0.04245186224579811,
-0.04185494780540466,
-0.024319130927324295,
-0.003252434777095914,
0.05439586192369461,
0.017488019540905952,
0.020529... |
<p>I have learned that for fluids and gases $P_\text{total}=P_\text{dynamic} + P_\text{static}$.</p>
<p>Suppose we have a closed circular tube in a form of ring filled with air under some pressure. In this case I believe the following is true.</p>
<p>$P_t = P_s$ as $P_d=0$.</p>
<p>No suppose some kind of propeller ... | g18407 | [
0.043980516493320465,
-0.015925368294119835,
-0.006413569208234549,
0.020301440730690956,
0.0627281442284584,
0.06110444664955139,
0.04425300285220146,
-0.004481911659240723,
-0.07278270274400711,
-0.03762170299887657,
-0.024553129449486732,
0.02522011287510395,
0.02923448383808136,
-0.015... |
<p>A current carrying conducting wire is placed in a magnetic field, and hence, accelerates. Assuming the wire is moving in a constant magnetic field, will the electrons change direction due to the field? </p>
<p>If so, would that change the direction of the Lorentz force acting on the conductor?</p>
<p>Will the elec... | g18408 | [
0.007064493838697672,
0.030729515478014946,
0.018413789570331573,
0.007388264872133732,
0.036436304450035095,
0.06955961883068085,
-0.008956559002399445,
0.018787624314427376,
-0.03702159970998764,
0.009727380238473415,
-0.024151507765054703,
0.0495421402156353,
-0.06436778604984283,
-0.02... |
<p>Is it possible to create a certain design of a conductor to reduce eddy currents greatly? So that the magnetic "breaking" can be reduced? </p>
<p>Is it even possible for the force generated by the eddy currents to become negligible?</p> | g18409 | [
-0.009925557300448418,
0.04439736530184746,
0.005980183370411396,
-0.007733204867690802,
0.0625104308128357,
0.039749033749103546,
-0.008745246566832066,
0.05433531850576401,
-0.037264369428157806,
-0.008212530985474586,
-0.026215769350528717,
-0.007468082010746002,
-0.023400459438562393,
... |
<p>I have a two mass and a pulley system as shown here: <img src="http://i.stack.imgur.com/leuTC.jpg" alt="enter image description here"></p>
<p>I have the following two questions:</p>
<p>First, why does $\dfrac{d^2}{dt^2} y_p$ is not zero, i I mean I don't understand why does $ y_p$ is going to change over time (it'... | g18410 | [
0.03244931995868683,
0.044184569269418716,
-0.005772726610302925,
-0.021517042070627213,
0.06044572591781616,
-0.010402428917586803,
0.043464384973049164,
0.009439164772629738,
-0.08201272040605545,
-0.034359049052000046,
-0.060996536165475845,
0.034130822867155075,
0.05158871039748192,
0.... |
<p>I've been looking at some papers on wakefields of electron beams and I am a little confuded about the units. They do not specify whether or not they are in cgs or SI units. Here is a sample equation:</p>
<p><img src="http://i.stack.imgur.com/CbEpg.png" alt="enter image description here"></p>
<p>I am assuming that ... | g18411 | [
0.022261714562773705,
0.03402647003531456,
-0.00791098177433014,
-0.015546213835477829,
0.03015834465622902,
-0.04937371984124184,
-0.03677557036280632,
0.02843967266380787,
-0.007142434827983379,
0.06921704858541489,
-0.0023297646548599005,
0.051355473697185516,
-0.02721223421394825,
0.00... |
<p>Mostly I have seen air bubbling used to remove impurities in the water itself, <a href="http://water.me.vccs.edu/courses/ENV115/Lesson5_print.htm" rel="nofollow">like exemplified in this course packet</a>.</p>
<p>This is called "Sparging," but I have yet to learn much about transfer between the air (constituents) a... | g18412 | [
0.020340831950306892,
0.01661141961812973,
-0.02215759828686714,
-0.002535336185246706,
0.004154656548053026,
0.06656099855899811,
0.06893592327833176,
0.052987053990364075,
0.006082526873797178,
0.015435404144227505,
-0.019488241523504257,
0.036285363137722015,
0.002908630995079875,
0.058... |
<p>I'm interested in tracking as much data about my runs as I can in an effort to get faster, and while I can easily estimate energy expenditure during an uphill run due to the change in elevation, I can't estimate energy expenditure due to the requirements of just keeping in motion. I could estimate wind resistance, c... | g18413 | [
0.03369123488664627,
0.017179347574710846,
-0.01714012585580349,
0.031447358429431915,
-0.0010836890432983637,
0.013647112064063549,
0.10584472864866257,
0.056222204118967056,
-0.0769045501947403,
-0.025497715920209885,
-0.03298354521393776,
0.005601093638688326,
0.022998524829745293,
0.03... |
<p><strong>Edit</strong></p>
<p>It seems that I haven't written my question clearly enough, so I will try to develop more using the example of quantum tunnelling. As a disclaimer, I want to state that my question is not about how to perform a Wick rotation in the path integral formulation!</p>
<p>Let's look a the pro... | g18414 | [
0.01750505156815052,
-0.0034965521190315485,
0.011955083347856998,
0.005359546281397343,
-0.013713927008211613,
-0.022489966824650764,
0.030951274558901787,
0.05828641355037689,
-0.0473746582865715,
0.049673207104206085,
-0.025536470115184784,
-0.00011871616152347997,
0.009816928766667843,
... |
<p>What "large size" unit of length could be considered at the opposite end of spectrum from Planck's length?</p>
<p>Is there a table of smallest and largest value for various physical quantities that can be defined from well-known constants? </p>
<p>Edit</p>
<p>I was teaching the exponential function and scientific... | g18415 | [
0.007944121956825256,
0.04870324954390526,
-0.011356841772794724,
-0.11654697358608246,
-0.011205554008483887,
0.01911155879497528,
-0.022201085463166237,
-0.03794725984334946,
-0.05257800966501236,
-0.006321888882666826,
0.004070313181728125,
0.00611806008964777,
0.020480817183852196,
0.0... |
<p>I am trying to understand the concept of depolarization of light by various particle shapes. For example, depolarization light scattered (re radiated) from a sphere illuminated with vertically polarized light. </p>
<p>Is my picture an accurate representation of why light is depolarized? Essentially are the electron... | g18416 | [
0.0036073513329029083,
0.019043348729610443,
-0.02093314938247204,
0.005628849379718304,
0.07810268551111221,
-0.00966998003423214,
0.01390535943210125,
-0.023257417604327202,
0.018376966938376427,
-0.005522547289729118,
-0.004854151979088783,
0.04226833954453468,
0.0435887835919857,
0.010... |
<p>A news has recently became viral that physicists have discovered a geometrical object that simplifies a lot our models quantum physics. For an outsider like me, it is difficult to actually understand the significance of that finding. </p>
<p>Is it actually a new model that literaly makes every quantum physics book ... | g18417 | [
-0.0002601735177449882,
0.052033502608537674,
0.005198713392019272,
-0.03871621936559677,
0.04419325292110443,
-0.0016195449279621243,
0.039390679448843,
0.023943426087498665,
-0.01088718418031931,
-0.0008282261551357806,
0.011851831339299679,
-0.053209591656923294,
0.050826072692871094,
-... |
<p>If we set up an evacuated vessel where we keep one end at a higher temperature than the other, and then introduce a liquid at the warm end, it will evaporate and condense at the cooler end. If we trap the liquid there, all the liquid will move to the cooler end.</p>
<p>What limits the speed of this mass transfer?</... | g18418 | [
-0.0020167138427495956,
0.0052352952770888805,
-0.00022602149692829698,
0.029110394418239594,
0.03214441239833832,
-0.004566485993564129,
0.061256587505340576,
0.017928075045347214,
-0.09578945487737656,
0.0008035353966988623,
-0.007900416851043701,
0.040579378604888916,
0.025980019941926003... |
<p>I've been given the following problem, and I'm quite lost with it.</p>
<p>Let $L_1$, $L_2$, and $L_3$ denote the abstract o(3) algebras. You are given that $\vec{A} = (A_1, A_2, A_3)$ and $\vec{B} = (B_1, B_2, B_3)$ transform as vector operators of o(3).</p>
<p>Show that $[L_j, \vec{A} \cdot \vec{B}] = 0$</p>
<p>... | g18419 | [
-0.0023061521351337433,
0.0060120029374957085,
-0.03684519976377487,
-0.04091591760516167,
0.023086585104465485,
-0.06643693149089813,
0.04991848021745682,
0.02941187284886837,
0.028103457763791084,
0.046424251049757004,
-0.09097453206777573,
0.04867005720734596,
-0.0074574933387339115,
-0... |
<p>We know that, in the double slit experiment, observation changes the behavior of a quantum object, that it behaves like a particle when observed and a wave when not observed. But why should its nature depend on observation? What if we didn't exist and hence no observation...? The nature of the quantum objects must r... | g18420 | [
0.009994080290198326,
-0.015184745192527771,
0.025348473340272903,
-0.02878030203282833,
0.07168519496917725,
0.0613655187189579,
0.039785198867321014,
0.06225607171654701,
-0.007685618940740824,
-0.07576311379671097,
0.03523697704076767,
0.06083051860332489,
0.035251181572675705,
0.048110... |
<ol>
<li><p>Is there a relation between the number of dimensions of space time and the number of fundamental forces? </p></li>
<li><p>Also, did the universe always have 4 space time dimensions? </p></li>
<li><p>And could there exist a world where the electromagnetic field was broken such that there would be 5 fundament... | g18421 | [
0.022816136479377747,
0.05634479969739914,
-0.000030186274670995772,
-0.0170731358230114,
0.010886955074965954,
0.04311966150999069,
-0.007663138210773468,
-0.03087196685373783,
-0.05911402031779289,
-0.04568466916680336,
-0.014709805138409138,
-0.06065920367836952,
0.0033499356359243393,
... |
<p>So it's that time of year again, where one must buy gifts for all children in sight.</p>
<p>I want to buy a book, related to physics, ideally, for my girlfriend's sister. What books are educational and informational for a 9-year-old? At that age I was reading Stephen Hawking's "Universe in a Nutshell", so I know I'... | g18422 | [
0.011934317648410797,
0.07245095819234848,
-0.0006659990176558495,
-0.04997127130627632,
0.031153691932559013,
0.05378121882677078,
-0.01257607713341713,
-0.050021447241306305,
0.05547501891851425,
-0.020577924326062202,
0.012419156730175018,
-0.011075330898165703,
0.05356067791581154,
-0.... |
<p>Ok, my understanding of physics is still limited, hoping to change that in the following years, but I have a question.</p>
<p>Dark energy is what provokes the expansion of the universe, so, in theory, it must be exerting some kind of "anti-gravity", definitely an energy as I see it.</p>
<p>Would it be possible to ... | g569 | [
0.028712324798107147,
0.07145257294178009,
0.027529487386345863,
-0.0007530553848482668,
-0.002217876957729459,
0.005918747745454311,
-0.04949677363038063,
0.048047617077827454,
-0.03985411301255226,
-0.025754418224096298,
0.016501490026712418,
0.008458131924271584,
-0.01572509855031967,
-... |
<p>I am trying to figure out a formula that, given an initial thrust value, will give me the thrust value that I need to apply to each thruster (red) to make the overall thrust be straight up with no rotation. The kicker is that the center of mass (green) is offset and variable.</p>
<p>Example:<img src="http://i.stack... | g18423 | [
0.043800052255392075,
0.05275515094399452,
-0.026173697784543037,
-0.029219862073659897,
-0.012649551965296268,
0.005559692159295082,
0.027839312329888344,
0.002985207363963127,
-0.07118860632181168,
0.002773451153188944,
0.007631530053913593,
0.007979515939950943,
0.0034658254589885473,
-... |
<p>Does the Grashof number lead to the answer?
The Wikipedia article (<a href="https://en.wikipedia.org/wiki/Grashof_number" rel="nofollow">https://en.wikipedia.org/wiki/Grashof_number</a>) yields an equation for vertical plates $$Gr_L = \frac{g\beta(T_s-T_\infty L^3)}{\nu^2}$$ Could I just solve for $L$, with $Gr_L$ ... | g18424 | [
0.11077385395765305,
0.020006751641631126,
-0.011274432763457298,
-0.024904765188694,
0.09283780306577682,
0.01815595105290413,
0.04140467941761017,
-0.014867518097162247,
-0.01790597103536129,
-0.038742661476135254,
-0.08155577629804611,
0.08048183470964432,
-0.01212267205119133,
0.007915... |
<p>If the transition of the electrons result in production of photons, Is photon creation is instantaneous? </p>
<p>If Yes,At what moment rightly the photon gets created?</p>
<p>Else, Will the photon be stationary until it is fully energized?</p> | g18425 | [
0.035527490079402924,
0.020839495584368706,
-0.003804258070886135,
0.005831096787005663,
0.050248194485902786,
0.007501949090510607,
0.03549166023731232,
0.05453573912382126,
-0.028551120311021805,
0.05248023942112923,
-0.04117312282323837,
0.015413983725011349,
-0.04691915214061737,
-0.02... |
<p>I'm reading through chapter 7 of Green-Schwarz-Witten and I have a problem with the derivation of the M-tachyon correlation function. Basically I'm trying to get 7.A.17 from 7.A.12 and eq 7.A.22 in the appendix of the first volume.</p>
<p>Basically I want to prove:</p>
<p>$$\langle\frac{V(k_1,y_1)...V(k_M,y_M)}{y_... | g18426 | [
0.07925829291343689,
-0.05190487578511238,
0.009338083676993847,
-0.028455378487706184,
0.006594550795853138,
0.024620583280920982,
0.03666621074080467,
0.005789361894130707,
-0.027610477060079575,
0.005398186855018139,
-0.041649553924798965,
0.008388089947402477,
0.03341209888458252,
0.10... |
<p><a href="http://en.wikipedia.org/wiki/Conductivity,_temperature,_depth" rel="nofollow">Conductivity, temperature, depth</a> sensors are used by oceanography to calculate the velocity of sound at varying depths.</p>
<p>These measurment values are used to comprise sound velocity profiles like the one below to increas... | g18427 | [
0.04786871373653412,
-0.058836679905653,
-0.0025267566088587046,
-0.0497606061398983,
0.09447173774242401,
-0.0012319666566327214,
0.05851415917277336,
-0.005794854834675789,
-0.042524535208940506,
0.02397913858294487,
-0.10253757238388062,
0.04567639157176018,
0.0315491259098053,
0.019069... |
<p>If wavefunction is $\phi$, we know that $|\phi (x)|^2$ represents probability of finding a particle at $x$. </p>
<p>Now let us talk about some pedagogical example in spontaneous symmetry breaking in QFT, Mexican hat potential.</p>
<p>$V(\phi,\phi^\dagger) = -\frac{1}{2}\mu^2|\phi|^2 + \frac{\lambda^2}{4}|\phi|^4$<... | g18428 | [
0.012911292724311352,
0.034822460263967514,
-0.021555311977863312,
-0.011872855946421623,
0.04576532542705536,
-0.020318200811743736,
0.037854794412851334,
0.005929616745561361,
-0.026461336761713028,
-0.001699376618489623,
-0.008025571703910828,
0.023053795099258423,
0.030749276280403137,
... |
<p>Imagine there is a strong magnet at <code>(0, 0)</code>. There is a horizontal rail on <code>y=1</code> on which a ferromagnetic object rides. The object can only move on the rail. No friction anywhere.</p>
<p>The object starts at <code>(0, 1)</code> with some positive velocity.</p>
<p>How will the graph of its mo... | g18429 | [
0.01888277754187584,
0.09232940524816513,
-0.009920258074998856,
0.042331263422966,
0.058333221822977066,
-0.004450022242963314,
0.04833594709634781,
0.012579362839460373,
-0.030117634683847427,
-0.043859563767910004,
-0.02004402130842209,
0.025859981775283813,
0.048727598041296005,
-0.041... |
<p>Nuclear fission requires the mass of the fissile material above the critical mass. So that the explosion takes place at least in the case of a nuclear bomb. But once a single nucleus got involved in the reaction, the reaction can't be stopped easily if I'm right.
<strong>A single nucleus how do know about the c... | g18430 | [
0.03680843487381935,
0.020718727260828018,
0.028020162135362625,
0.07255062460899353,
0.008105261251330376,
0.007174243684858084,
-0.02734161540865898,
0.06379780918359756,
-0.039689090102910995,
-0.09401039779186249,
-0.06657059490680695,
-0.05260276794433594,
0.03012092411518097,
-0.0086... |
<p>As far as quantum observation, when a human observes electrons going through the double whole experiment, have scientist tried having a blind person observe the experiment to see if the electrons actually can tell if a person is able to view it or not? This will tell us a lot as far as how intelligent the electrons... | g75 | [
-0.024748757481575012,
0.03122619539499283,
0.03709276765584946,
-0.0227428637444973,
0.02029208093881607,
-0.007375709712505341,
-0.02678839862346649,
-0.005173784680664539,
0.042656220495700836,
0.020918311551213264,
0.009440990164875984,
0.03782975301146507,
0.03180787339806557,
0.01071... |
<p>In whole mechanics, we never talk about wasted vibrational energy!
As we see in our daily life, a lot of energy is wasted as vibrational energy in every engine, for example as we fire our car's engine, it starts vibrating.</p>
<p>Use of this energy would increase the efficiency of engine. As we see that a big part ... | g18431 | [
0.026708470657467842,
-0.010935338214039803,
0.03129538521170616,
0.03882822021842003,
0.04179755598306656,
-0.043621279299259186,
0.016734328120946884,
0.04173273220658302,
-0.05087320879101753,
0.01450356189161539,
0.06789577752351761,
-0.007133131381124258,
-0.006484585348516703,
-0.006... |
<p>I would like to derive the partition function for the quantum Harmonic oscillator from scratch: </p>
<p>$$\tag{1} Z = \int dp \, dx\, e^{-\beta H}.$$</p>
<p>The free particle appears in many textbooks. $H = p^2$ so it is a Gaussian integral</p>
<p>$$\tag{2} Z = \int dp \, dx \, e^{-\beta p^2} = L \int dp \, e^... | g18432 | [
0.02535708248615265,
0.0003967702214140445,
-0.021436668932437897,
-0.050925709307193756,
0.0454159751534462,
-0.006010111421346664,
0.05901888757944107,
0.04183099791407585,
-0.013723121955990791,
0.028849685564637184,
-0.05498478189110756,
0.0031818333081901073,
-0.029949113726615906,
0.... |
<p>When a light wave passes from one medium to other, the wavelength of the light wave changes and the frequency remains constant.
If then color of the light waves depends on changing wavelength or Frequency?</p> | g18433 | [
0.030524929985404015,
-0.03298165276646614,
0.042609959840774536,
-0.01725410297513008,
0.033504001796245575,
-0.0018166756490245461,
-0.022614475339651108,
-0.03577603027224541,
0.002989138476550579,
-0.02929013967514038,
0.02020302228629589,
0.02100449427962303,
0.013515064492821693,
0.0... |
<p>How do you determine the energy of an isotope? I there a calculation for it? Sorry for the confusion</p> | g18434 | [
0.03724135085940361,
0.012971440330147743,
0.006143095437437296,
-0.0025717299431562424,
-0.006195517256855965,
0.002520442707464099,
-0.04958399385213852,
0.07590688019990921,
-0.041915856301784515,
-0.031041156500577927,
-0.04183691367506981,
-0.017871424555778503,
-0.007056980859488249,
... |
<p>Let's say you are modeling some process with the wave equation $\frac{1}{c^{2}}\frac{\partial^{2}\psi}{\partial t^{2}} = \nabla^{2}\psi$. You wish to improve your model by including dispersive effects, but you want your model to be as simple as possible for computational tractability. </p>
<p>What is the minimal ap... | g18435 | [
0.0021016292739659548,
-0.04580288380384445,
0.013492900878190994,
0.005934001877903938,
0.0487043634057045,
-0.043841127306222916,
0.04081181064248085,
0.06976373493671417,
-0.05060802027583122,
-0.016540611162781715,
0.03827301785349846,
-0.004569103475660086,
0.006267326883971691,
0.067... |
<p>Suppose that we have a charged capacitor with two pins: $ C_+ $ and $C_-$. </p>
<p>Suppose that we have a long wire with fixed geometry, that is already connected to the pin C+.<br>
Let the distance along the wire be called $s$. </p>
<p>I closed a circuit by connecting another end of the wire t... | g18436 | [
0.0583312027156353,
-0.04737107828259468,
-0.023302465677261353,
-0.04277173802256584,
0.06236732378602028,
0.00581798329949379,
0.06608736515045166,
-0.05330302566289902,
-0.10656367987394333,
0.01798032782971859,
-0.06259068101644516,
0.041188083589076996,
0.04213641211390495,
-0.0010461... |
<p>Third Newton's law, $F_{1->2} = -F_{2->1}$</p>
<p>So, how does a body react with the same force that it's receiving from the acting body? Is it the electric interactions at the subatomic level? When we sit on the chair, does that mean we are just bringing our electrons in contact with the electrons of the cha... | g18437 | [
0.042319826781749725,
0.048740386962890625,
-0.028589390218257904,
0.0271027572453022,
0.054225239902734756,
0.03888995572924614,
-0.012782739475369453,
0.03604365885257721,
0.0022950954735279083,
-0.024020014330744743,
-0.04098057001829147,
0.028843237087130547,
-0.0078073409385979176,
-0... |
<p>In Carroll's online Lecture Notes on General Relativity (p112) he says, "the weakness of the gravitational field allows us to decompose the metric into the Minkowski form plus a small perturbation"</p>
<p><img src="http://i.stack.imgur.com/mnlOe.gif" alt="enter image description here"></p>
<p>He then says that, to... | g18438 | [
0.013812645338475704,
-0.0006311232573352754,
-0.028330979868769646,
-0.07243506610393524,
0.03544648364186287,
0.058339063078165054,
0.02597879245877266,
0.03206207603216171,
-0.0663137137889862,
-0.060089800506830215,
-0.025943759828805923,
-0.010029329918324947,
0.08054128289222717,
-0.... |
<p>Where exactly does CMB come from. I've seen it in documentaries as a huge sphere with Earth in the middle. But if all this radiation was ejected from the start of the universe some time after the big bang; why can we see it? Surely the radiation should be travelling away from us? Just like every galaxy is?</p> | g18439 | [
0.056021444499492645,
0.010738362558186054,
0.03366216644644737,
0.014516624622046947,
-0.05272969603538513,
0.048437606543302536,
0.03138525411486626,
0.050034359097480774,
0.013280716724693775,
-0.08203887194395065,
0.029898306354880333,
0.06745707988739014,
0.05028901249170303,
0.021459... |
<p>This question is about whether the mass of a particle increases with its speed. Here is my related question from which <em>this</em> question spawned: <a href="http://physics.stackexchange.com/questions/133376/why-is-there-a-controversy-on-whether-mass-increases-with-speed">Why is there a controversy on whether mass... | g18440 | [
0.07347503304481506,
0.0455867163836956,
0.038867488503456116,
-0.025466889142990112,
0.07594876736402512,
-0.010610249824821949,
-0.012379702180624008,
0.014997648075222969,
-0.04772455245256424,
-0.024494046345353127,
0.044847521930933,
0.0036940169520676136,
-0.01096511259675026,
0.0368... |
<p>My book says that when a photon carrying a certain amount of energy hits an electron, that gets excited and goes on an higher energetic level, absorbing the energy of the photon. When it comes back to its main energetic level it emits another photon. </p>
<ol>
<li><p>Is this second photon having the same frequency ... | g18441 | [
0.04345295950770378,
0.001968600321561098,
0.0126925865188241,
-0.005191547330468893,
0.08143147826194763,
-0.009203988127410412,
-0.026270583271980286,
0.02664678543806076,
-0.037392642349004745,
-0.0010537629714235663,
-0.018303122371435165,
0.03343869373202324,
0.04456225782632828,
-0.0... |
<p>I recently came across this tutorial and wondered why vapor will come out when the cap comes off. <a href="http://www.wikihow.com/Make-a-Water-Bottle-Cap-Pop-off-with-Air-Pressure" rel="nofollow">Heres the Tutorial</a> </p>
<p><img src="http://i.stack.imgur.com/Pwbg1.jpg" alt="enter image description here"></p> | g18442 | [
0.013479389250278473,
-0.03216443210840225,
0.014601402916014194,
0.05389036610722542,
0.036647308617830276,
0.013111055828630924,
-0.007971585728228092,
0.08979519456624985,
0.0034805128816515207,
0.02950100600719452,
-0.0012744063278660178,
0.001875558402389288,
0.06020285189151764,
0.00... |
<p>Is there a simple and quick formula to find the weight (the force acting) on each leg, especially when legs are astride and they are not equally stretched?</p>
<p><img src="http://i.stack.imgur.com/lUesD.jpg" alt="enter image description here"></p>
<p>(or, better) not equally distant from the center of mass? Can y... | g18443 | [
0.06476429849863052,
0.06114446371793747,
-0.01774323359131813,
-0.04232720658183098,
0.030202798545360565,
-0.0052082291804254055,
0.08450896292924881,
-0.016516221687197685,
-0.04069549962878227,
-0.01817069761455059,
-0.026770854368805885,
-0.03585590422153473,
0.010335498489439487,
-0.... |
<p>When people talk about the first superstring revolution they often mention the miraculous cancellation of anomalies via the Green Schwarz mechanism. My question is whether such a string-theoretic mechanism is also at work when the 4D gravitational and gauge-gravitational anomalies are tackled? In this context, would... | g18444 | [
0.07156050950288773,
0.014753973111510277,
0.007181572262197733,
0.00367772881872952,
-0.00601857528090477,
0.06068367511034012,
-0.013273604214191437,
0.03272665664553642,
-0.019335780292749405,
-0.01721258834004402,
-0.03366922214627266,
-0.0501231774687767,
0.009493590332567692,
0.03462... |
<p>Is this just a historical artifact - that the particle physics community decided at some point to call all of the pre-oscillation physics by the name the "Standard Model"? The reason I ask is because I often see articles and books say something to the effect "the strongest hint of physics beyond the SM are the non-z... | g18445 | [
0.05645802244544029,
0.05683354660868645,
0.03407389298081398,
-0.017011139541864395,
0.014121952466666698,
0.04388333857059479,
0.007688444573432207,
0.041742630302906036,
0.014135744422674179,
-0.07707483321428299,
0.007510009687393904,
-0.025142567232251167,
0.04057454690337181,
0.02550... |
<p>I want to expand my understanding of physics and just watched a Feynman lecture where he said "every theoretical physicist who is any good knows six or seven different theoretical representations for exactly the same physics".</p>
<p>Trying to think of such different representations, I can see mechanics which can b... | g18446 | [
0.023616012185811996,
0.06015406921505928,
0.0014289075043052435,
-0.03587046265602112,
0.06351978331804276,
-0.0146084139123559,
-0.0003224975080229342,
-0.013394951820373535,
0.0019288351759314537,
-0.040683142840862274,
0.05455456301569939,
-0.04254031926393509,
0.027861958369612694,
0.... |
<p><img src="http://i.stack.imgur.com/Owoii.png" alt="enter image description here"></p>
<p>SO I was working on Atwoods, when I came up with the following problem, It is more complicated but i should understand this simpler scenario first.</p>
<p>As shown in the diagram above, (Atwood machine), mass $m_{2}$, is held ... | g18447 | [
0.09733399748802185,
0.020362164825201035,
0.002091107191517949,
-0.0023534486535936594,
-0.00123591348528862,
0.004727536346763372,
0.0935325101017952,
-0.03531983867287636,
-0.06726138293743134,
0.03789407014846802,
-0.004456391092389822,
0.01393087673932314,
0.02285759150981903,
0.02297... |
<p>In this thread <a href="http://physics.stackexchange.com/questions/121920/integrating-the-generator-of-the-infinitesimal-special-conformal-transformation/122283?noredirect=1#comment249123_122283">Integrating the generator of the infinitesimal special conformal transformation</a>, the generator of the 'flow' of the t... | g18448 | [
0.024370718747377396,
0.03741255775094032,
-0.02540648728609085,
-0.06774411350488663,
0.005330307874828577,
0.01788650080561638,
0.007585814222693443,
0.09337065368890762,
-0.03466745465993881,
-0.01509778294712305,
-0.04512893408536911,
0.010617171414196491,
0.020794671028852463,
-0.0537... |
<p>I was wondering if the following steps would result in a net displacement on a spacecraft operating in Earth's magnetic field:</p>
<ol>
<li>Turn on a superconductor</li>
<li>Use a linear actuator to shift some mass</li>
<li>Turn off the superconductor</li>
<li>Shift the mass back to its original position</li>
<li>R... | g18449 | [
0.005445550195872784,
0.09183081984519958,
-0.012138581834733486,
-0.039590027183294296,
0.02516815811395645,
0.054813239723443985,
-0.0011349188862368464,
-0.017542654648423195,
-0.038801077753305435,
-0.031895942986011505,
-0.03170057758688927,
0.002325714100152254,
-0.042528193444013596,
... |
<p>Hello this is expanding upon a question that was previously asked on stack exchange that I linked below. From what I understand of Black Holes is that overtime Hawking Radiation results in the Black Hole shrinking. This being do to virtual particle pairs. The point I find confusing, and I may be misunderstanding it,... | g570 | [
0.0536205992102623,
0.006337051745504141,
0.0321124903857708,
-0.00371388322673738,
0.024936191737651825,
0.06423496454954147,
0.0028636360075324774,
0.053564269095659256,
-0.015447127632796764,
0.0004465728998184204,
0.03199702873826027,
0.031197790056467056,
0.0020640131551772356,
0.0229... |
<p>It took a while to find relativity and the various subtle (or unmeasurable) effects it has within our universe. Is it possible that, although Newton's gravitational force equation leaves out any notion of density or size, this too might impact the forces acting around us?</p>
<p>I noticed <a href="http://physics.s... | g18450 | [
0.03638770431280136,
0.016392109915614128,
0.025891577824950218,
-0.01003688108175993,
0.03332443907856941,
0.0361916609108448,
0.0014721561456099153,
0.024780500680208206,
-0.06940068304538727,
-0.03768962249159813,
0.03091416135430336,
-0.05196851119399071,
0.02701754681766033,
-0.025302... |
<p>So the momentum operator in coordinate space is:
$$ \vec{p} = -i\hbar\vec{\nabla}$$
And the hamiltonian for a free particle is:
$$ H = \frac{p^2}{2m}$$
All over the internet I see this written as:
$$ H = \frac{\vec{p}^2}{2m} = -\frac{\hbar^2}{2m}\nabla^2 $$
But it seems like the sign on the RHS is wrong. It seems li... | g18451 | [
0.01731105148792267,
-0.010557637549936771,
-0.042680829763412476,
-0.0035228203050792217,
0.08434179425239563,
0.010591799393296242,
0.09226524829864502,
0.00027469603810459375,
-0.02516322024166584,
0.019976256415247917,
-0.0018566130893304944,
0.04494505003094673,
0.005496250931173563,
... |
<p>The prerequisite for adiabatic quantum evolution of single photon or biphoton system is as follows.</p>
<p>We have to prepare a single photon or biphoton quantum system which has a ground and a higher level energy state. Is that allowed in physics?</p>
<p>If we consider a single photon quantum system, higher energ... | g18452 | [
-0.01313125528395176,
0.061952415853738785,
0.0008073011413216591,
-0.013522909954190254,
0.04443712905049324,
0.03349914029240608,
0.03038734942674637,
0.05667266994714737,
0.04733460396528244,
-0.019466666504740715,
-0.027660096064209938,
0.044632669538259506,
0.010048290714621544,
0.031... |
<p>I am a high school student trying to teach himself quantum mechanics just for fun, and I am a bit confused. As a fun test of my programming/quantum mechanics skill, I decided to create a computer program to model an atom.</p>
<p>Initially, I learned about the <a href="http://en.wikipedia.org/wiki/Matrix_mechanics">... | g18453 | [
0.008423632942140102,
-0.0505947545170784,
-0.023388072848320007,
-0.05274105817079544,
0.061298172920942307,
-0.02327611856162548,
0.0013306462205946445,
0.052118126302957535,
0.04009431600570679,
-0.005865976680070162,
-0.024339761584997177,
0.004399335943162441,
0.025702523067593575,
-0... |
<ul>
<li><p>What do we actually mean when we say that matter is a wave?</p></li>
<li><p>What does the <strong>wavelength</strong> of this matter wave indicate?
The idea of a particle behaving like a wave is kinda incomprehensible to me. </p></li>
<li><p>Further, why is the wavelength inversely proportional to the mome... | g18454 | [
0.045891836285591125,
-0.013695664703845978,
-0.008628271520137787,
-0.04027891531586647,
0.12837688624858856,
0.07425875216722488,
-0.05708727240562439,
0.018514439463615417,
-0.002286875154823065,
-0.029975781217217445,
0.03195299953222275,
0.03461587429046631,
-0.011158453300595284,
0.0... |
<p>Why the acceleration of free-falling bodies become zero after some time? My only idea would be that the closer to the core of Earth we are, the value of "g" the lower becomes (since the mass below the body is lower and consequently, its gravitational force is also lower) but it works on large scales, like hundreds a... | g18455 | [
0.07539370656013489,
0.0627540647983551,
0.007431024219840765,
0.0036477542016655207,
0.0351443774998188,
0.07139752060174942,
0.024675222113728523,
0.0058019268326461315,
-0.0492660291492939,
-0.09826929867267609,
-0.038964513689279556,
0.005314710550010204,
0.05061127617955208,
0.0242638... |
<p>The early universe was hot and opaque. Once it cooled enough, protons and electrons were able to form hydrogen atoms. This made the universe transparent, and was known as <strong>recombination</strong>. We can see the effects of this as the <strong>cosmic microwave background radiation</strong>.</p>
<p>How precisel... | g18456 | [
0.03259183093905449,
-0.02659771218895912,
0.015959113836288452,
-0.02199791558086872,
-0.02154519222676754,
0.032783105969429016,
0.022499296814203262,
0.060281019657850266,
0.03599734231829643,
-0.010829190723598003,
-0.022160466760396957,
0.028975823894143105,
0.019231878221035004,
0.06... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://physics.stackexchange.com/questions/31395/what-happens-to-matter-in-a-standard-model-with-zero-higgs-vev">What happens to matter in a standard model with zero Higgs VEV?</a> </p>
</blockquote>
<p>What if the Higgs did not have a "Mexican h... | g571 | [
0.0033301152288913727,
-0.002593010663986206,
0.012037917040288448,
0.03181114420294762,
0.0642780065536499,
0.026449188590049744,
-0.06746542453765869,
0.04895874857902527,
0.004408581182360649,
-0.05145997926592827,
-0.04323162883520126,
-0.004620302002876997,
0.019652266055345535,
0.046... |
<p>I was recently caught up in a situation where I tried to explain to someone with only vary basic knowledge of physics (notion of atoms and electrons, etc.) what causes superconductivity. One thing I was unable to explain though was why superconductors work only at low temperatures.</p>
<p>Superconductivity is cause... | g18457 | [
0.06211380288004875,
0.07323438674211502,
0.015544768422842026,
0.015658024698495865,
0.029201138764619827,
0.07292284071445465,
0.011040721088647842,
0.03779103234410286,
-0.03836863115429878,
-0.039600636810064316,
-0.054420411586761475,
0.036277562379837036,
-0.030374625697731972,
0.007... |
<p>I'm studying the $U(N)$ gauge theory theory in 0+1 dimensions. The aim is to show that this is equivalent to a matrix model. Is there any literature on this topic?</p>
<p>The action I am interested in is</p>
<p>$$
S_E = \int d\tau \text{Tr} \left[ \left( D_\tau \Phi \right)^\dagger \left( D_\tau \Phi \right) + m^2... | g18458 | [
-0.05646917223930359,
0.005277230404317379,
-0.011966326273977757,
-0.009753044694662094,
0.03614593297243118,
-0.010800391435623169,
0.03050774149596691,
0.022660335525870323,
0.022296814247965813,
0.008351292461156845,
0.05309603735804558,
0.0026556795928627253,
-0.015218758955597878,
0.... |
<p>The Kerr black hole solutions gives an analytic continuation that is asymptotically flat. Some people have argued that this is another universe, but others state that the analytic continuation represent the same space-time region at different times.</p>
<p>The Kerr solution is an exact, analytic solution for an ete... | g18459 | [
0.004688977263867855,
-0.011961656622588634,
0.03125305846333504,
-0.06995007395744324,
-0.013104243203997612,
0.00820966437458992,
-0.01894710585474968,
0.0032840650528669357,
0.003276331117376685,
-0.007005210965871811,
0.02202378585934639,
-0.06499997526407242,
0.04703320935368538,
0.07... |
<p>I have 2 coordinate systems which move along $x,x'$ axis. </p>
<p>I have derived a Lorentz transformation for an $x$ component of momentum, which is one part of an 4-momentum vector $p_\mu$. This is my derivation:</p>
<p>$$
\scriptsize
\begin{split}
p_x &= mv_x \gamma(v_x)\\
p_x &= \frac{m (v_x'+u)}{\left(... | g18460 | [
0.018643992021679878,
-0.03847300261259079,
-0.02193385362625122,
-0.023716259747743607,
0.02352694422006607,
0.01224159449338913,
0.020582398399710655,
-0.0022193158511072397,
0.01135445386171341,
-0.008373822085559368,
0.007354287430644035,
0.05996562913060188,
-0.023248925805091858,
-0.... |
<p>Recent calculations agree that a merging pair of supermassive black holes can emit enough gravitational waves to eject themselves from a galaxy. </p>
<p>Could NGCC 1277, a small galaxy with a 17 billion solar-mass black hole (see the <a href="http://www.nature.com/nature/journal/v491/n7426/full/nature11592.html" r... | g18461 | [
0.019085047766566277,
0.04588324949145317,
0.01058641541749239,
-0.04660103842616081,
0.056764837354421616,
0.03101564198732376,
-0.03916937857866287,
-0.014523088000714779,
-0.02628513239324093,
-0.015466892160475254,
0.00038827923708595335,
-0.039519667625427246,
0.07440033555030823,
0.0... |
<blockquote>
<p>An object is falling and it weighs 25 kg (on a scale, presumably). What is its mass?</p>
</blockquote>
<p>I know that weight is measured in Newtons and mass in kilograms, but what if a problem states that something weighs in kilograms? Would I still use $\text w=mg$? </p> | g18462 | [
0.029055284336209297,
0.003381559858098626,
-0.004220847971737385,
-0.023374175652861595,
0.0014764702646061778,
0.01829569973051548,
-0.0076869479380548,
0.00561400456354022,
-0.09719348698854446,
0.019177092239260674,
-0.034234967082738876,
-0.03958373889327049,
0.006312010809779167,
0.0... |
<p>I have seen two forms of <a href="http://en.wikipedia.org/wiki/Linear_response_function" rel="nofollow">linear response</a>: </p>
<ol>
<li><p>One is in the calculation of susceptibilities using Green functions. </p></li>
<li><p>The other is in the evaluation of response currents, say, London current of a supercondu... | g18463 | [
0.031003722921013832,
-0.020100869238376617,
-0.00839884951710701,
-0.02384881302714348,
0.047213517129421234,
-0.004533266182988882,
0.04124962538480759,
0.05671543627977371,
-0.04678470641374588,
-0.015922794118523598,
-0.04838861897587776,
0.03883223980665207,
0.043989505618810654,
0.00... |
<p>Hopefully this is a simple question, I just can't seem to get my mind around it.</p>
<p>I'm to take the limit of the Fermi-Dirac distribution for $T \rightarrow 0$.</p>
<p>In this limit the chemical potential is equal to the Fermi energy $\mu = \epsilon_F$, and all states of energy below the Fermi energy is occupi... | g18464 | [
0.0065537081100046635,
0.05235454440116882,
0.014371778815984726,
-0.04689346253871918,
0.07913947105407715,
-0.026854831725358963,
-0.012594194151461124,
0.0464555062353611,
-0.03549674525856972,
-0.04279293492436409,
-0.03742123395204544,
-0.025311779230833054,
-0.005605384241789579,
0.0... |
<p>I know that the velocity of a wave is given by $v=\lambda f$ but what does this velocity represent in the physical sense. For instance, if I am told a car moves at a velocity of 5 $m/s$ I know that the car itself will cover 5 meters in displacement every second. What part of the wave is moving at velocity $v$?</p> | g18465 | [
0.08525682985782623,
0.0012427448527887464,
-0.002031691139563918,
-0.0007838899036869407,
0.061999738216400146,
-0.004354463890194893,
0.009309998713433743,
0.014431769959628582,
-0.048189807683229446,
-0.064273402094841,
0.019678423181176186,
-0.009556632488965988,
0.013559369370341301,
... |
<p>I have two question,</p>
<ol>
<li><p>why group velocity represents energy or information transmission?</p></li>
<li><p>what is the relation between phase velocity and Special relativity: <strong>why can it exceed C without violation of SR</strong>?</p></li>
</ol>
<p>I didn't take any classes in special relativity... | g18466 | [
0.01602914184331894,
0.03550971299409866,
-0.005936999339610338,
0.029884107410907745,
0.026919199153780937,
0.009994175285100937,
0.032624419778585434,
0.05398464947938919,
-0.046275779604911804,
0.0033967066556215286,
0.01815836876630783,
0.014171437360346317,
-0.01035257987678051,
0.030... |
<p>$$\langle x^2 \rangle = \int_{-\infty}^\infty x^2 |\psi(x)|^2 \text d x$$</p>
<p>What is the meaning of $|\psi(x)|^2$? Does that just mean one has to multiply the wave function with itself?</p> | g18467 | [
-0.02142450027167797,
0.013377796858549118,
-0.005292536690831184,
-0.07180839031934738,
0.021052148193120956,
-0.01850207895040512,
0.012998702004551888,
0.018946334719657898,
-0.036850329488515854,
-0.02817610651254654,
-0.06311547011137009,
0.00038970113382674754,
-0.0016396204009652138,
... |
<p>When Sun and Earth are moving, at each moment $t$ they are attracted not to the <strong>current</strong> position of each other, but to the position of each other at $t-\Delta t$, where $\Delta t$ is the time required for gravity to propagate the distance between each other. Laplace computed the effect of this "reta... | g18468 | [
0.04194469004869461,
0.031847551465034485,
0.009522296488285065,
-0.00869695283472538,
0.0055016581900417805,
0.050929199904203415,
0.0950707271695137,
-0.02960049733519554,
-0.07093163579702377,
-0.03547339513897896,
0.02177124097943306,
-0.03071318194270134,
0.03753456845879555,
0.031168... |
<p>I just recently watched <a href="http://www.youtube.com/watch?v=DfPeprQ7oGc">a video</a> where they were explaining the double slit experiment.</p>
<p>I understand that the interference pattern would be observed if you send photons or electrons one after the other.
The conclusion that the author seems to make is th... | g18469 | [
0.0004442148783709854,
0.04627637192606926,
0.02660137042403221,
-0.013429585844278336,
0.03662040829658508,
0.0002847099967766553,
0.005209625232964754,
0.049124665558338165,
0.019548574462532997,
-0.022022681310772896,
0.02160622365772724,
0.03216499835252762,
0.011332420632243156,
-0.00... |
<p>I was wondering if someone can provides some clear experimental signatures of a topological superconductors ? </p>
<p>I was thinking about that, because for topological insulator, one of the hallmarks is the insulating behaviour of the bulk versus the metallic behaviour at the edge. So, a good experimental signatur... | g18470 | [
-0.026749633252620697,
0.0110235083848238,
0.020416567102074623,
-0.0219061691313982,
0.07972318679094315,
-0.01818898506462574,
0.002348189940676093,
0.0633288249373436,
0.05158467963337898,
-0.024770937860012054,
0.037291932851076126,
-0.012312887236475945,
0.04136275127530098,
0.0028913... |
<p>Imagine an electron and a positron, initially held stationary some distance apart at time $t=0$. There is an attractive force between them, so they will approach one another.</p>
<p>I am told that all the fundamental laws of physics are CPT-symmetric, so let's try that out.</p>
<p>First, a P-inversion. Reflect the... | g18471 | [
0.020665913820266724,
-0.005609684158116579,
-0.019452514126896858,
-0.04556543380022049,
0.12885844707489014,
0.04461126774549484,
0.014104084111750126,
0.016869276762008667,
-0.08634557574987411,
-0.012870696373283863,
0.009981377981603146,
-0.0011666459031403065,
0.003218310885131359,
-... |
<p>Difference between <a href="http://en.wikipedia.org/wiki/Lagrangian_and_Eulerian_specification_of_the_flow_field" rel="nofollow">Eulerian and Lagrangian formulation</a> of Fluid Dynamics.</p>
<p>I am completely new to fluid mechanics. Until now definition $F = ma$ was sufficient for me to solve any rigid body probl... | g18472 | [
0.1110982671380043,
-0.04721381515264511,
0.009527896530926228,
-0.029900331050157547,
0.07344168424606323,
-0.026411253958940506,
0.08685719966888428,
-0.009794368408620358,
-0.07987338304519653,
-0.05079033225774765,
0.01294357143342495,
-0.01683971658349037,
0.05980353802442551,
0.06052... |
<p>The effect of rotation can be considered by modelling the nucleus as a rotating body, characterised by some moment of inertia. Then how The Hamiltonian describing rotation is?</p>
<blockquote>
<p>$$H_{rot}=\frac{\hbar^{2}}{2\Im}R^{2}$$</p>
</blockquote>
<p>where:</p>
<p>$R$ is the rotational angular mome... | g18473 | [
0.00196851952932775,
0.012215221300721169,
-0.027418209239840508,
-0.033619485795497894,
0.05905776098370552,
-0.049622539430856705,
0.0749836340546608,
0.04965844377875328,
-0.024225404486060143,
0.03109138458967209,
-0.0010161782847717404,
-0.008175820112228394,
-0.03627772256731987,
0.0... |
<p>Starting with the Einstein-Hilbert Lagrangian</p>
<p>$$ L_{EH} = -\frac{1}{2}(R + 2\Lambda)$$</p>
<p>one can formally calculate a gravitational energy-momentum tensor </p>
<p>$$ T_{EH}^{\mu\nu} = -2 \frac{\delta L_{EH}}{\delta g_{\mu\nu}}$$</p>
<p>leading to</p>
<p>$$ T_{EH}^{\mu\nu} = -G_{\mu\nu} + \Lambda g_... | g18474 | [
0.02735264040529728,
0.06017329543828964,
0.011224597692489624,
-0.05379828065633774,
0.03677618131041527,
0.037596266716718674,
0.005494251381605864,
0.05246150866150856,
-0.09268585592508316,
-0.029146509245038033,
0.01559000089764595,
-0.03176625072956085,
0.06146971508860588,
-0.043726... |
<p>I heard that If we travel for long distances in the direction of the rotation of the earth, we can gain some extra hours in the journey.
Is it true? What if we travel in the opposite direction?</p> | g18475 | [
-0.011148929595947266,
0.08345698565244675,
0.01977016218006611,
-0.0026415574830025434,
0.007063461467623711,
0.038474030792713165,
0.011146417818963528,
-0.032203469425439835,
-0.0044962093234062195,
-0.004025254398584366,
-0.01673634722828865,
-0.013277403078973293,
0.0191027969121933,
... |
<p>When we consider a bicycle is turning on a flat plane, we know that there is friction, which provide centripetal force on the bicycle. And we know that the bicycle is no longer perpendicular to the flat plane so as to reach equilibrium.
What I want to ask why we always choose the center of gravity of the bicycle be ... | g18476 | [
0.004590453580021858,
0.054858140647411346,
-0.0009801486739888787,
0.0005030299653299153,
0.049620747566223145,
0.013123502023518085,
0.09644176810979843,
-0.008815697394311428,
-0.06564470380544662,
0.004910952877253294,
0.0072060092352330685,
-0.040383826941251755,
-0.0006033870158717036,... |
<p>I have been trying to understand the last step of this derivation. Consider a sphere made up of charge $+q$. Let $R$ be the radius of the sphere and $O$, its center.</p>
<p>A point $P$ lies inside the sphere of charge. In such a case, Gaussian surface is a spherical shell,whose center is $O$ and radius is $r$ (=OP)... | g18477 | [
0.02365843392908573,
-0.027728084474802017,
-0.03426293656229973,
-0.04378393292427063,
0.04688084125518799,
0.039022691547870636,
0.037284914404153824,
-0.05341636389493942,
0.010346746072173119,
0.04391033947467804,
-0.04318278282880783,
0.037207357585430145,
0.03362856060266495,
0.01082... |
<p>While doing some on-the-side reading, I stumbled across this question: <a href="http://physics.stackexchange.com/q/6197/23473">Do two beams of light attract each other in general theory of relativity?</a>. Great question and a great, easily understandable answer. In short, it explains that General Relativity allows ... | g18478 | [
0.08170657604932785,
-0.04815871641039848,
0.007380657829344273,
0.031070835888385773,
-0.0012194556184113026,
-0.01616680808365345,
0.07531788945198059,
0.040957625955343246,
-0.05509483069181442,
-0.003975887782871723,
0.05407314375042915,
-0.0019123939564451575,
-0.02136124111711979,
-0... |
<p>This might be silly question. It's about the rotation of the Earth and the objects moving on it. If I jump into the air, why did I also move with the Earth though I am in the air? I am supposed to be land in backward/forward location, as it keeps rotating. But this doesn't happen. What is this phenomenon called? </p... | g162 | [
0.0395241379737854,
0.044408995658159256,
0.003681330941617489,
0.04990139603614807,
0.019224554300308228,
0.08508224785327911,
0.08023922890424728,
0.013806854374706745,
0.006167998071759939,
-0.08469279855489731,
-0.002727363957092166,
-0.03930753469467163,
0.0380447618663311,
-0.0067656... |
<p>I have accumulated a large amount of R/C gear over the years. I have several antennas which are not labelled as to their original use. This antenna is either for 5.8ghz, 2.4ghz, or 910mhz.</p>
<p><img src="http://i.stack.imgur.com/qVfp6.jpg" alt="enter image description here"></p>
<p>The connector is SMA with a ma... | g18479 | [
0.004164927639067173,
-0.09750542044639587,
-0.004719685297459364,
-0.012339774519205093,
0.04236869141459465,
-0.031006556004285812,
0.06646406650543213,
-0.004197913222014904,
0.00773251336067915,
-0.021434234455227852,
0.0025749613996595144,
0.04827336594462395,
0.02400011196732521,
-0.... |
<p>Even if we can't have single quarks in nature because of the charge colour, what would be the result of the collision of two down quarks at high velocities (0,99% c) at high energies, like the ones of LHC proton's collision..?</p> | g18480 | [
0.07239587604999542,
0.028020324185490608,
-0.0077227381989359856,
-0.01643633283674717,
0.11692281067371368,
0.021376734599471092,
-0.029839294031262398,
0.01189463585615158,
-0.02640197053551674,
-0.06247788295149803,
0.0029774680733680725,
0.02870522066950798,
0.006228263955563307,
-0.0... |
<p>If some fundamental particles, like leptons or quarks are composite (e.g.in preonic models), or the same with gauge bosons or the higgs particles. </p>
<p><strong>How could it be possible that preons were more massive than the "known" elementary particles?</strong></p>
<p>Remark: I think to remember there are som... | g18481 | [
0.008305630646646023,
0.019909163936972618,
0.02799057401716709,
-0.03142441064119339,
0.03726761043071747,
0.03617960587143898,
0.0120113305747509,
0.04207487776875496,
-0.00825654249638319,
0.03539049252867699,
-0.025774667039513588,
-0.025090165436267853,
0.0366097055375576,
0.026460874... |
<p>I am trying to find the stagnation point of a fluid flow from a complex potential. The complex potential is given by $$\Omega(z) = Uz + \cfrac{m}{2\pi}\ln z.$$ From this I found the streamfunction to be $\psi=Ur\sin\theta + \cfrac{m}{2\pi}\theta$ and the velocity potential to be $\phi=Ur\cos\theta + \cfrac{m}{2\pi}\... | g18482 | [
0.021489810198545456,
-0.023611966520547867,
-0.005964428652077913,
-0.04582659527659416,
0.05702982842922211,
-0.0225343219935894,
0.07489582151174545,
-0.00871357973664999,
-0.0341741219162941,
0.028366874903440475,
-0.008679264225065708,
-0.03820282593369484,
0.0015400720294564962,
0.01... |
<p>I know that electrons and protons have a spin of 1/2, whereas photons have a spin of 1,.</p>
<p>However, I do not know how this is determined? How is it determined? </p> | g18483 | [
-0.03051326423883438,
-0.0260593444108963,
-0.031287115067243576,
0.01965988054871559,
0.07893053442239761,
-0.004210198298096657,
0.032732266932725906,
0.03382193297147751,
0.019812317565083504,
-0.014403882436454296,
-0.01992783322930336,
0.03507622331380844,
-0.00908153597265482,
-0.030... |
<p>Does the rotation of ceiling fan makes air circulate in a spiral, circular motion beneath the radius of fan or the air from outside is also mixed with it and replaces the air in room? </p>
<p>A specific example would be room filled with smoke or else, does ceiling fan clears it by throwing the smoke + air mix... | g18484 | [
0.034003548324108124,
-0.01663275808095932,
0.010863409377634525,
0.04894403740763664,
0.021427134051918983,
0.00000722211643733317,
0.08360584825277328,
0.003998796921223402,
-0.012594552710652351,
-0.006861337926238775,
-0.05240118131041527,
0.049915630370378494,
-0.02576490491628647,
0.... |
<p>Why is it that when you look in the mirror left and right directions appear flipped, but not the up and down? </p> | g421 | [
-0.03401803970336914,
-0.01061431597918272,
-0.03473691642284393,
0.008427130058407784,
0.029034754261374474,
0.0417042039334774,
0.07661012560129166,
0.07336822897195816,
0.02433076873421669,
-0.05344980210065842,
0.04234704375267029,
0.00037562765646725893,
0.05248500034213066,
-0.002813... |
<p>I have some questions about the released energy and power of a nuclear fission bomb.</p>
<ul>
<li>What are the key dependencies of the power of a fission bomb?</li>
<li>Is it true that the power of a fission bomb depends linearly on the mass of the bomb? If so, why?</li>
<li>Is there a simple physical argument to e... | g18485 | [
-0.023189602419734,
0.02208881638944149,
0.017142167314887047,
0.043186772614717484,
-0.0375024639070034,
-0.0014657484134659171,
-0.04237888380885124,
0.013925195671617985,
-0.047327231615781784,
-0.011573917232453823,
-0.0667671337723732,
-0.015380380675196648,
-0.025663532316684723,
0.0... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.