question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Let's say I initially have an open, empty, soda can. I then turn it over and lower it into a bowl of water, and then release it. Obviously water rises to some level in the cup and then there is air at the top of the can, which was initially the bottom.</p>
<p>Are there only three forces on the can once it reaches e... | g9073 | [
-0.007493486627936363,
0.022498920559883118,
0.009915748611092567,
0.012646178714931011,
0.05784771591424942,
0.026435252279043198,
0.01931430771946907,
-0.039509788155555725,
-0.07765179127454758,
-0.018886711448431015,
-0.047345489263534546,
-0.027584727853536606,
-0.03005191497504711,
-... |
<p>When construct spin liquid by projective symmetry group, we can classified spin liquids by the invariant group (IGG) of their mean field ansatze. For example, we can have Z2, U(1) and SU(2) spin liquids. In my understanding, IGG is equivalent to the low-energy gauge fluctuation. However, I am confused whether states... | g9074 | [
-0.026041952893137932,
-0.019275784492492676,
-0.014797420240938663,
-0.020616775378584862,
0.05212276428937912,
0.017719127237796783,
0.02556731551885605,
0.025994764640927315,
-0.04218386113643646,
0.006396125070750713,
0.020357146859169006,
-0.009451965801417828,
0.018879491835832596,
-... |
<p>This is about continuity equation. What does the last integral mean?
$$\frac{\mathrm{d}Q_V}{\mathrm{d}t}=\iiint_V \mathrm{d}^3x \,\frac{\partial\rho}{\partial t}=-\iiint_V\! \mathrm{d}^3x\,\operatorname{div}\,\mathbf{j}=-\iint\limits_{\partial V}\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\;\;\;\subset\!\supset \mathbf j\;\cdo... | g9075 | [
0.07721808552742004,
-0.01525970920920372,
-0.06017124280333519,
0.0024195790756493807,
0.017803603783249855,
0.05685877799987793,
0.053947508335113525,
-0.008206023834645748,
-0.01249721273779869,
-0.012662936002016068,
-0.06844733655452728,
0.039733000099658966,
-0.0032267991919070482,
-... |
<p>After recently going through a short program of self-study in quantum mechanics, I was surprised to find a quote attributed to Feynman essentially saying he was extremely bothered by the computational process of renormalization. It's "dippy" that anyone should have to subtract one infinity by another in order to arr... | g9076 | [
-0.031885284930467606,
0.038735393434762955,
0.0041136471554636955,
-0.06245878338813782,
0.04138931259512901,
-0.038791242986917496,
0.03903817757964134,
0.06427425146102905,
-0.004266516771167517,
-0.004266891162842512,
-0.044293344020843506,
-0.014182314276695251,
-0.010299582965672016,
... |
<p>The canonical quantization of a quantum field prescribes that given a lagrangian, one can quantize the theory by imposing the commutation relations between the field operators and their conjugated momenta.The field operators are then obtained by solving the equation of motion for plane waves.</p>
<p>However, why is... | g9077 | [
0.04625297710299492,
-0.028572622686624527,
-0.019259348511695862,
0.011729275807738304,
0.048012882471084595,
-0.025104671716690063,
0.055279504507780075,
0.03797958418726921,
0.007250139955431223,
-0.03951103240251541,
-0.016803668811917305,
0.019270503893494606,
-0.08413224667310715,
0.... |
<p>Suppose you know kx,ky,kz points along with the corresponding energies. Basically, you know about the 4-D E(k) dispersion.</p>
<p>How you do then convert that data into the bandstructure plots you commonly see which show E(k) along a closed path through high-symmetry points through the Brillouin zone?</p> | g9078 | [
0.009137093089520931,
-0.04074322059750557,
0.00004234094376442954,
-0.033139266073703766,
-0.009696443565189838,
0.000844741181936115,
0.02590824104845524,
0.020996158942580223,
-0.007449311204254627,
-0.020021039992570877,
0.010292373597621918,
0.015314644202589989,
0.05975496023893356,
... |
<p>This should be simple, but it keeps bothering me. If a rigid body has no fixed axis, and a torque (defined relative to a point $A$) is applied, it will rotate around $A$. But often I can also calculate the torque relative to another point $B$ (which often seems to be non-zero too). So does this mean that the rigid b... | g9079 | [
0.06122496724128723,
-0.0026234425604343414,
0.013020883314311504,
0.036067742854356766,
0.05349912494421005,
-0.03926534578204155,
0.08680929243564606,
0.06388315558433533,
-0.04627970606088638,
-0.02539665810763836,
-0.030336584895849228,
0.0036186459474265575,
0.028377119451761246,
-0.0... |
<p>Why if the earth is spinning at 1000mph a person falls from 10 stories his body didn't land about 1.4 miles away but right down as if the earth didn't spin at all</p> | g9080 | [
0.06925175338983536,
0.02487468719482422,
-0.020152343437075615,
0.020794229581952095,
0.05398477986454964,
0.08198055624961853,
0.08091810345649719,
0.027750058099627495,
-0.023166503757238388,
-0.05297107249498367,
-0.036506641656160355,
-0.06327411532402039,
-0.001151345088146627,
0.009... |
<p>I've been reviewing derivations of the spherical harmonics in quantum mechanics; mostly as review but also to make sure I understand where the concepts arise from. </p>
<p>However, every derivation I've seen makes use of the following differential equation/ identity that seemingly comes from nowhere. I've not yet b... | g9081 | [
0.07040821015834808,
-0.044758185744285583,
-0.00035676307743415236,
-0.06521400809288025,
0.0469745397567749,
0.048762768507003784,
0.05634193494915962,
0.016234001144766808,
0.0005733536090701818,
-0.03471316024661064,
-0.05456036701798439,
-0.010377204976975918,
0.08769058436155319,
0.0... |
<p>Going to word this question a bit more straightforward than I may have before. Also, I'm trying to use baby formulas so I can grasp exactly what's going on.</p>
<p>Object A has an elasticity of <code>Y</code>, and is propped against an effectively immobile rigidbody.</p>
<p>Object B is a rigidbody with mass <code... | g9082 | [
0.03442820906639099,
0.03902725130319595,
0.00028603526880033314,
0.014930320903658867,
0.05112982168793678,
-0.0011550892377272248,
0.05603250488638878,
-0.0024294364266097546,
-0.04935630038380623,
-0.04140280932188034,
0.0151517977938056,
0.022659583017230034,
0.07392760366201401,
-0.06... |
<p>An electric charge $Q$ is distributed through out a nonconducting sphere of radius $r_ 0$ and has a spherical cavity of radius $r_1$ centered at the sphere's centre. Assume the charge $Q$ is distributed in the shell (i.e. between $r=r_1$ and $r=r_0$ ) and that the charge density varies as ρ= $(ρ_0 ∗r_1/r)$ Find t... | g300 | [
0.05031865835189819,
0.00527504738420248,
-0.01137989480048418,
-0.019098790362477303,
0.0709974393248558,
0.018616747111082077,
0.031958188861608505,
-0.04042289778590202,
0.028107699006795883,
0.01469381619244814,
-0.03325226530432701,
0.010444412007927895,
0.013350266963243484,
0.041281... |
<p>I did a Standard Model calculation and I want to compare my answer to a measured value.</p>
<p>Does anyone know the literature value for the forward-backward asymmetry $\frac{\sigma_F - \sigma_B}{\sigma_F + \sigma_B}$</p>
<p>for the process $e^+e^- \to \mu^+\mu^-$ on the $Z$ resonance (where $\sigma_F = \int_0^1 d... | g9083 | [
-0.010044250637292862,
0.0245366133749485,
0.0015999628230929375,
-0.02295565791428089,
0.04435800015926361,
0.01955454610288143,
0.06317311525344849,
0.047165870666503906,
-0.023840773850679398,
0.020488811656832695,
0.0379280261695385,
0.00931873545050621,
0.032070208340883255,
0.0497639... |
<p>Imagine that two widely separated charged particles $A$ and $B$ exchange a photon.</p>
<p>Because they are far apart one can imagine that there is a major contribution to the photon propagator that travels at the speed of light from $A$ at a time $T_0$ to $B$ at a time $T_1$ where $T_1 > T_0$.</p>
<p>But in tha... | g9084 | [
0.030762186273932457,
0.03320222347974777,
-0.007183282636106014,
-0.003325472120195627,
0.06922465562820435,
0.025690026581287384,
0.048379797488451004,
0.07557684928178787,
-0.020063303411006927,
0.016577107831835747,
0.04467310011386871,
0.027271084487438202,
-0.015094252303242683,
-0.0... |
<p>I was talking with an acquaintance about lightning, and we came up with opposite theories and predictions for the frequency of lightning over ocean.</p>
<ul>
<li><p>My theory is that since seawater is a fluid riddled with ions, the charges can move to equalize with whatever field is applied to it; therefore it shou... | g9085 | [
0.06042671203613281,
0.06695092469453812,
-0.020198408514261246,
-0.02261223830282688,
0.029597489163279533,
0.04236361384391785,
0.017364416271448135,
0.0035562897101044655,
-0.010037803091108799,
-0.03377407044172287,
0.035839568823575974,
0.0175497904419899,
0.04244900494813919,
0.00825... |
<p>PHYSICS of Brushing your teeth:
I spent a few weeks a few years ago, five minutes here and there, trying to figure out what is the optimal amount of water that you should put in your mouth to get the maximum rinsing effect after you brush your teeth. Do you fill your mouth half full, 1/3 full or what? If you want t... | g9086 | [
0.08219721168279648,
0.046244364231824875,
0.025159478187561035,
0.07493942975997925,
0.007183167152106762,
-0.004929529037326574,
-0.0038359160535037518,
0.009107757359743118,
-0.013254913501441479,
-0.010125944390892982,
0.05016675591468811,
-0.05482811480760574,
-0.026816125959157944,
0... |
<p>Usually one is led to think of an electron moving from the valence band to the conduction band as an electron leaving the atom it is bound to in the lattice, and becoming free to move, while leaving apart a hole that is free to move as well. How accurate is that picture, how useful is it, and what does it really mea... | g9087 | [
-0.04289901256561279,
0.01873345486819744,
-0.004683979786932468,
-0.021893829107284546,
0.029809653759002686,
-0.03681153059005737,
0.08272366970777512,
0.045275263488292694,
0.05247106775641441,
0.01337984949350357,
-0.051869213581085205,
0.03166618198156357,
0.04202637821435928,
-0.0183... |
<p>I would like some book reference regarding the history of physics. I'm a civil engineering student, and I want to have some basics on the type of developments regarding my field of specialization (structures). For example, I want to look at something and know "No, this can't be it, because this is a physics concepti... | g9088 | [
0.05696409195661545,
0.07612856477499008,
0.005620007403194904,
0.01530849002301693,
0.03163095563650131,
0.032562773674726486,
0.029529739171266556,
0.021564558148384094,
0.04004914313554764,
-0.03458448499441147,
0.06213059276342392,
0.031863946467638016,
0.022755108773708344,
-0.0334121... |
<p>What is the most common definition of <a href="http://en.wikipedia.org/wiki/Heavy-tailed_distribution#Definition_of_long-tailed_distribution" rel="nofollow">long tailed distribution</a> for physicists? I am looking for definition and examples. Examples should have arguments why the distribution is or is not long tai... | g9089 | [
0.07630061358213425,
0.04581805691123009,
-0.01181798242032528,
-0.06917880475521088,
0.029248682782053947,
-0.003911118023097515,
0.03270144388079643,
-0.026182357221841812,
-0.021376455202698708,
-0.046153388917446136,
-0.036273907870054245,
0.02101348340511322,
0.011587853543460369,
0.0... |
<p>Normally water molecules are electrically neutral.
But I have seen somewhere ideas about electric energy generators mentioning that water droplets might be used in some applications as they are charged particles.</p>
<p>Is it really so? </p>
<p>I know that water droplets <a href="http://en.wikipedia.org/wiki/Tribo... | g9090 | [
0.04623543843626976,
0.06957081705331802,
-0.009771942161023617,
-0.000670062261633575,
0.0725456029176712,
0.08785820007324219,
-0.05339910089969635,
0.019722186028957367,
0.0272690262645483,
0.014882715418934822,
-0.017771843820810318,
0.008322113193571568,
0.04530709609389305,
0.0195981... |
<p>I have seen this post:</p>
<p><a href="http://www.nydailynews.com/news/politics/new-infrared-laser-weapon-shoot-drones-disable-ships-navy-article-1.1311093" rel="nofollow">New infrared laser weapon, the Laser Weapons System, could shoot down drones or disable ships: US Navy</a></p>
<p>You can watch the <a href="ht... | g9091 | [
-0.009258829988539219,
-0.01383674144744873,
-0.00037721716216765344,
0.003384145675227046,
0.0704079270362854,
0.03980504348874092,
-0.036181870847940445,
0.06344910711050034,
-0.02250075899064541,
-0.0736938938498497,
-0.016098888590931892,
0.08065501600503922,
0.06304851174354553,
0.031... |
<p>This might be a bit more of an engineering question, but I'm calculating air density drop-off with altitude, and I'm having some problems calculating the pressure (I'll run through my method). <a href="http://en.wikipedia.org/wiki/Density_of_air#Altitude" rel="nofollow">This has been very useful in explaining</a>, b... | g9092 | [
0.04377823323011398,
-0.04900706559419632,
-0.04020167142152786,
0.04622775688767433,
0.00028841185849159956,
0.05323607847094536,
0.023418627679347992,
0.034068763256073,
-0.07689584046602249,
0.023030128329992294,
-0.013769363984465599,
-0.005064150784164667,
0.007885578088462353,
0.0242... |
<p>I have a problem with the Hamiltonian, I don't think anything to solve it!!
So could you give me some hints!</p>
<ul>
<li>Knowing that:
$$\left[ {{{\hat p}_i},{{\hat q}_k}} \right] = \frac{\hbar }{i}{\delta _{ik}}.$$</li>
</ul>
<p>Hamiltonian is: </p>
<p>$$\begin{array}{l}
\hat H = \hat q_i^{},\hat q_i^2,\hat q... | g9093 | [
-0.00019386879284866154,
0.026316650211811066,
-0.030649153515696526,
-0.04327689856290817,
0.07705411314964294,
-0.008673968724906445,
0.07163680344820023,
-0.03776964917778969,
-0.0004801084869541228,
0.001510332920588553,
-0.003060731803998351,
0.06969446688890457,
-0.08700580894947052,
... |
<p>It is stated in many popular science videos that one of the reasons that quantum mechanics is so wacky is that if you measure which slit the photon/particle went through on the way, then you no longer get the interference pattern. I want to ask how that is done? How do we detect which slit it went through?</p> | g9094 | [
0.028928546234965324,
0.007896161638200283,
-0.0024196109734475613,
-0.05166231468319893,
0.0377490296959877,
0.014749916270375252,
0.04401494190096855,
0.04829420521855354,
0.021707186475396156,
-0.04485349357128143,
0.005250893998891115,
0.04702839255332947,
0.03419551998376846,
0.023116... |
<p>I'm new to field theory and I don't understand the difference between a "local" functional and a "non-local" functional. Explanations that I find resort to ambiguous definitions of locality and then resort to a list of examples. A common explanation is that local functionals depend on the value of the integrand "at ... | g9095 | [
0.026632193475961685,
-0.03954995051026344,
0.006894263438880444,
-0.046770334243774414,
0.07604114711284637,
-0.015494797378778458,
0.08227677643299103,
0.052940063178539276,
-0.0071589285507798195,
-0.0077206771820783615,
-0.11625009030103683,
0.021450135856866837,
-0.011843396350741386,
... |
<p>Whenever you hear someone illustrating/describing the transmission of radio waves they always make it seem like they'd travel perfectly around the Earth to another distant location. For example, a radio wave sent by alternating current to be received from an intercepting device on the other side of the planet.
You'... | g9096 | [
-0.014269799925386906,
0.046361908316612244,
0.0008133012452162802,
-0.007884577848017216,
0.06776372343301773,
0.016429990530014038,
0.02968408912420273,
0.031876470893621445,
-0.054367415606975555,
-0.06669420748949051,
0.05773990601301193,
0.009743135422468185,
0.03127525746822357,
0.01... |
<p>This is a question about terminology. To me, it's clear that the nucleus of an atom is still an atom. But a comment by Willie Wong at <a href="http://physics.stackexchange.com/questions/11562/is-nature-symmetric-between-particles-and-antiparticles/11563#comment-28303">Is nature symmetric between particles and antipa... | g9097 | [
0.026614677160978317,
-0.003995069302618504,
-0.0009164077928289771,
-0.07150314748287201,
0.1035386249423027,
0.004402426071465015,
0.0035177012905478477,
-0.020131023600697517,
0.009144719690084457,
-0.026361942291259766,
0.04788654297590256,
0.041817035526037216,
-0.03210665285587311,
-... |
<p>As I understand it fusion inside a sun can produce heavier and heavier elements until some sort of "nucleus size limit" is reached. As far as I understand, the limit is thought to be reached with the element iron.</p>
<p>What accounts for this "fusion element limit"? Is it the battle between the nuclear strong forc... | g9098 | [
-0.004905153531581163,
0.08813971281051636,
0.006584656424820423,
0.017620809376239777,
0.019020717591047287,
0.01904194988310337,
-0.023165864869952202,
0.019692854955792427,
-0.02537381276488304,
-0.04042267054319382,
0.02188696153461933,
0.01830309070646763,
-0.0010520471259951591,
-0.0... |
<p>I am building a preheater for a maple syrup evaporator and am going to use the steam generated by the heating process to pre-heat the incoming sap from, say 5 degrees C to (hopefully) something on the order of 80-90 C. (the goal is to heat the sap/fluid before it gets into the evaporating pan so that we are more ef... | g9099 | [
-0.002343125408515334,
-0.021138688549399376,
0.02394491247832775,
0.008892402052879333,
-0.053900640457868576,
-0.038958918303251266,
0.02442300319671631,
0.03245123103260994,
-0.05050516873598099,
-0.04493691399693489,
-0.02541820891201496,
0.014158584177494049,
0.03760623559355736,
0.02... |
<p>This is a question taken from a past E&M exam</p>
<blockquote>
<p>A thick spherical shell (inner radius $R_1$ and outer radius $R_2$) is made of a dielectric material with a "frozen in" polarization $$P(r)=\frac{k}{r}\hat{r}$$ where $k$ is a constant and $r$ is the distance from the center. Find the electric ... | g9100 | [
0.015804141759872437,
0.004451492335647345,
-0.01326687727123499,
-0.005841395817697048,
0.03162640333175659,
0.012653561308979988,
-0.0028983759693801403,
0.023657215759158134,
0.00014102771820034832,
0.014412223361432552,
-0.06704745441675186,
0.039147812873125076,
0.027547523379325867,
... |
<p>I recently came up with the following concept. It is very simple, and may have been thought of before.
A picture says more than a thousand words, so here is it explained in a picture:</p>
<p><img src="http://i.stack.imgur.com/DQhdL.png" alt="Conveyor belt using densities of gases to keep it in motion">
<em>Note th... | g155 | [
0.07279237359762192,
0.051056165248155594,
0.0014455345226451755,
-0.015504561364650726,
0.03196810185909271,
0.014299428090453148,
0.05660959705710411,
0.02586674503982067,
-0.090372733771801,
-0.011344748549163342,
0.010178309865295887,
-0.03269735723733902,
0.013163833878934383,
0.04058... |
<p>Can you see or accurately visualise sub atomic particles or are they known only by maths and/or inference?</p> | g9101 | [
-0.018351512029767036,
0.03369962424039841,
-0.0038806672673672438,
-0.03555943816900253,
0.017897212877869606,
-0.0013849687529727817,
0.011357746087014675,
-0.006292113568633795,
0.029526149854063988,
-0.006071940995752811,
0.006791139021515846,
0.05202166363596916,
0.0626211166381836,
-... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://physics.stackexchange.com/questions/11542/why-is-gravitation-force-always-attractive">Why is gravitation force always attractive?</a> </p>
</blockquote>
<p>I have heard that the attractiveness of gravitation is due to the fact that it is a... | g81 | [
0.04199322685599327,
0.0316908061504364,
0.011863114312291145,
-0.03508782759308815,
0.035567909479141235,
0.09468630701303482,
0.01924777589738369,
0.011027785949409008,
-0.04578468203544617,
-0.031202876940369606,
0.05589230731129646,
0.03567355126142502,
0.02963179722428322,
0.025679355... |
<p>Suppose we have two black holes of radius $R_b$ orbiting at a distance $R_r$. I believe semi-classical approximations describe correctly the case where $R_r$ is much larger than the average black body radiation wavelength due to Hawking radiation. </p>
<p>Do we have approximations for Hawking radiation temperature ... | g9102 | [
-0.008130723610520363,
-0.008347413502633572,
0.025579804554581642,
0.010868936777114868,
-0.023198653012514114,
0.025187449529767036,
-0.02032136544585228,
0.02420646697282791,
-0.021696561947464943,
0.022314609959721565,
0.05866609886288643,
0.06473208963871002,
-0.033660102635622025,
0.... |
<p>Why cant one see the tidal effect in a glass of water like in an ocean?</p> | g9103 | [
0.05574461445212364,
-0.01076811645179987,
0.010745990090072155,
-0.04954073950648308,
0.033099494874477386,
0.06418795138597488,
0.03144521266222,
0.010813808999955654,
0.04053078591823578,
-0.0546627938747406,
0.07157114893198013,
0.06249971315264702,
0.04765958711504936,
0.0113848876208... |
<p>What if we apply a very strong magnetic field to an electron so that it's position be a constant. Then if it's position is constant, it's momentum will also be a constant. But it is in violation of Heisenberg's uncertainty principle, so is such an experiment possible?</p> | g9104 | [
0.019243378192186356,
0.026325087994337082,
0.01809621974825859,
-0.007394490297883749,
0.05052817985415459,
0.007358148228377104,
-0.03492739051580429,
0.08507265150547028,
-0.02226123958826065,
-0.003209561575204134,
-0.027232056483626366,
-0.02372848428785801,
-0.07116282731294632,
-0.0... |
<p>If I take an electrolytic capacitor, remove the aluminium casing, unroll the foil/ electrolyte-soaked paper, if charged, will it still work? And what if I took of the cathode foil and wrapped the anode foil with the paper around a metal rod -- will it work if charged? If not, why? </p> | g9105 | [
0.027740955352783203,
0.0046603623777627945,
0.023456187918782234,
-0.0058562601916491985,
0.03583633154630661,
0.009080859832465649,
-0.028156498447060585,
0.032595228403806686,
-0.006237294990569353,
0.0024006532039493322,
-0.010691963136196136,
0.06790917366743088,
0.03324451670050621,
... |
<p>I'm hoping to understand the motivation for certain parts of the definition of a derivative operator $\nabla$ on a manifold $M$. In Wald's General Relativity, two clauses of the definition are:</p>
<blockquote>
<ol>
<li><p>Commutativity with contraction: For all tensors $\mathit{A} \in \mathscr{T}(k,l)$, $\nabl... | g9106 | [
-0.0013256099773570895,
-0.0018670818535611033,
-0.02683120034635067,
0.047896016389131546,
0.01783442683517933,
-0.021586904302239418,
0.08096417039632797,
0.019120825454592705,
-0.06362684071063995,
0.003536046016961336,
-0.03886575251817703,
-0.024604488164186478,
0.06993267685174942,
-... |
<p>As far as i know potential difference between 2 points is defined as the negative line integral of electric field between those 2 points.
I also know that when magnetic field changes curl of electric field is not 0 and potential difference makes no sense.
But when we have an inductor in a rlc circuit then people alw... | g9107 | [
0.05165592208504677,
-0.010422853752970695,
0.005546629894524813,
0.025565659627318382,
0.08750443905591965,
0.001695253886282444,
0.0003155793237965554,
0.007173945661634207,
-0.06725449115037918,
0.002682069782167673,
-0.057919349521398544,
0.02735511213541031,
-0.011575620621442795,
-0.... |
<p>Consider you have a slab waveguide having n1=3.5 and n2=1.45. The value of critical angel is 24.5 degree approx. Similarly effective refractive index will be in between 1.45 and 3.5. How can we find the eigenvalue for this optical waveguide and plot in Matlab or some other software. </p>
<p>Thanks and hope it is cl... | g9108 | [
-0.00655193580314517,
0.004740355536341667,
0.02245226874947548,
-0.012304599396884441,
-0.04971765726804733,
-0.010123197920620441,
-0.006287497002631426,
0.002660563215613365,
-0.030478641390800476,
0.05118840932846069,
-0.004479183349758387,
0.03922102600336075,
0.02505972795188427,
0.0... |
<p>While the fasted emitted electrons comes from the fermi level of the material in UPS measurement, where does the slowest, which is called secondary electron cut-off orginate from? I really can't figure it out.
Also, why isn't the smallest kinetic energy zero? At least it should be nearly zero considering a rather c... | g9109 | [
0.06607797741889954,
0.01943744719028473,
-0.0009918422438204288,
0.04276322200894356,
0.029537174850702286,
-0.016106031835079193,
0.01276653166860342,
0.05454728752374649,
0.010026033036410809,
-0.02244878001511097,
0.016029948368668556,
0.04564959928393364,
0.010200374759733677,
-0.0170... |
<p>I was recently startled to find that the Earth's North Magnetic Pole is moving at upwards of 40 km per year, with an additional ~80 km daily elliptical drift about its mean position due to variations in solar wind. The <a href="http://en.wikipedia.org/wiki/North_Magnetic_Pole">Wikipedia article on the NMP</a> has a ... | g9110 | [
0.03715749830007553,
0.02585683949291706,
-0.03235343098640442,
0.00922221876680851,
0.05676700919866562,
0.023600980639457703,
0.03668558597564697,
0.0038916822522878647,
-0.03345869854092598,
0.0005662599578499794,
0.009108717553317547,
-0.057082079350948334,
0.0717226043343544,
0.016246... |
<p>Could a dying star in one brane ( assuming that we live in a world of multiple branes { not a Randal-Sumdrum model of a single brane}) be the start of the birth of the star ( more precisely Super Nova) in another brane? If so is the black hole merely the "Shadow" of the star's gravity in another brane ( because grav... | g9111 | [
-0.012297113426029682,
0.017651494592428207,
0.029866311699151993,
-0.010405102744698524,
0.012126808054745197,
0.05348915606737137,
-0.013484720140695572,
0.07148165255784988,
-0.0331752672791481,
-0.035474199801683426,
-0.04175198823213577,
0.01735488325357437,
0.07360000163316727,
-0.01... |
<p>I have seen multiple papers talking about the manifold, $M$ of the Neel order for an $SU(N)$ magnet is</p>
<p>$$M~=~\frac{U(N)}{U(m)\times U(N-m)}.$$</p>
<p>So for instance, a $SU(2)$ magnet has manifold</p>
<p>$$M ~=~ \frac{U(2)}{U(1)\times U(1)} ~\sim~ S^2.$$</p>
<p>Could someone explain to me physically how I... | g9112 | [
0.010195109061896801,
0.02036159671843052,
-0.02369062975049019,
-0.008787027560174465,
0.03530912846326828,
0.010094144381582737,
0.03211718797683716,
0.0627826452255249,
-0.037329427897930145,
-0.016607433557510376,
0.010085147805511951,
0.03895154222846031,
0.04236029088497162,
0.005143... |
<p>Is the oscillation of a simple pendulum in vacuum a case of perpetual motion? I recently read Feynman's lectures and he said perpetual motion is impossible in real life. But this pendulum in vacuum is pretty straightforward to achieve. </p> | g301 | [
0.06571653485298157,
0.03942031040787697,
0.02284134179353714,
0.008960138075053692,
0.019396256655454636,
0.027487777173519135,
0.016893023625016212,
0.02280120737850666,
0.001341198687441647,
0.00656852824613452,
-0.024035783484578133,
-0.013690446503460407,
-0.03694440424442291,
-0.0005... |
<p>I am currently working on the measurement of the coefficient of thermal expansion of copper. In order to compare my experimental results with theory or experiments made by others, I am looking for abacus or theoretical curves showing the latter coefficient (as a function of temperature).</p>
<p>The range of tempera... | g9113 | [
0.039134252816438675,
0.04363479092717171,
0.013147331774234772,
-0.017309613525867462,
-0.0025796242989599705,
-0.03316238895058632,
-0.005700405221432447,
-0.004942548926919699,
0.009290379472076893,
-0.014415216632187366,
-0.0038169946055859327,
0.04681415483355522,
0.031141262501478195,
... |
<p>On my last HW set, we were asked to show that the operator
$$\hat T = \exp(-ic\hat p /\hbar)$$
acts as a translation operator ($\hat T^\dagger q\hat T=q+c)$. This was simple to show using commutators and other such things. The same thing can be said with a momentum operator.</p>
<p>Can I have a translation operato... | g9114 | [
0.010951562784612179,
0.016546018421649933,
-0.007561990525573492,
0.004680784419178963,
0.02218819223344326,
-0.06773892790079117,
0.031122280284762383,
0.02145744487643242,
-0.010361133143305779,
0.006270599085837603,
-0.04230653867125511,
-0.015984147787094116,
0.015680445358157158,
-0.... |
<p>While there is no confirmation that quark stars exist, is there any theoretical limit analogous to (but different from) the <a href="http://en.wikipedia.org/wiki/Tolman%E2%80%93Oppenheimer%E2%80%93Volkoff_limit" rel="nofollow">Tolman–Oppenheimer–Volkoff limit</a> for neutron stars?</p>
<p>In other words, what is th... | g9115 | [
-0.0074004484340548515,
0.04971589520573616,
-0.0016912202117964625,
-0.06408748030662537,
-0.0021899982821196318,
0.017947273328900337,
-0.08591224998235703,
-0.028714969754219055,
-0.0400555357336998,
0.027353452518582344,
0.061241090297698975,
-0.03738958388566971,
-0.013659371994435787,
... |
<p>What is the conceptual difference between minimizing the availability of a thermodynamic system and maximizing the entropy of a thermodynamic system? I am under the impression that these are the same thing for the most part but occasionally have slightly different meanings. </p> | g9116 | [
0.025605663657188416,
-0.008500832132995129,
0.02641402930021286,
0.03722513094544411,
0.026938164606690407,
-0.0004386894288472831,
-0.04838258773088455,
0.037804003804922104,
-0.027295460924506187,
-0.00005890904867555946,
-0.02159130945801735,
-0.04307739809155464,
0.042919330298900604,
... |
<p>Is interstellar flight possible in the near future in a way that would keep our civilization alive?
I mean is it practically possible to obtain technology that would enable us to travel to nearby habitable earth-like planets to keep our civilization alive? </p>
<p>For example, consider this <a href="http://projecta... | g9117 | [
-0.02565125562250614,
0.04856647551059723,
0.01848990097641945,
0.03670740872621536,
0.0014414507895708084,
0.04082987830042839,
-0.040108174085617065,
-0.005315086338669062,
-0.02181265316903591,
-0.040427349507808685,
0.06232532858848572,
0.045627135783433914,
0.03811788931488991,
0.0089... |
<p>Is it possible to utilize gravitational waves as a delivery system for information between two observers straddling the event horizon of a black hole? And why ?</p> | g9118 | [
-0.018673790618777275,
0.056191202253103256,
-0.0014896972570568323,
-0.019891442731022835,
0.021463360637426376,
0.034072261303663254,
-0.04238291457295418,
-0.029931437224149704,
-0.05224776268005371,
-0.008160433731973171,
0.0375685952603817,
-0.0020300347823649645,
-0.0016664053546264768... |
<p>Can velocity and acceleration reach maximal values during the SHM simultaneously? Can you explain why?</p> | g9119 | [
0.08782214671373367,
0.029902607202529907,
0.007970921695232391,
0.08696630597114563,
0.08424406498670578,
0.012244612909853458,
-0.020307768136262894,
0.05172685533761978,
-0.03790158033370972,
-0.003474729135632515,
-0.03751697763800621,
-0.002794214291498065,
-0.015148612670600414,
0.02... |
<p>Consider a lattice of massive points connected by harmonic springs, with zero or periodic boundary conditions. If we make a repeating pattern of $N$ varying masses, the system will have $N$ bands of eigenfrequencies with real wave vectors and band gaps between these bands, where wave vectors are imaginary. If we the... | g9120 | [
-0.037481747567653656,
0.028835687786340714,
0.020922118797898293,
0.022947408258914948,
0.002512716455385089,
-0.010109745897352695,
-0.010306436568498611,
-0.015252543613314629,
0.021165117621421814,
-0.039562102407217026,
0.02130150981247425,
0.027802206575870514,
0.06089494004845619,
0... |
<p>When you look out at the white-caps on a wind-swept lake, you can see a dark, undulating pattern under the crests of the white-caps.</p>
<p><em>Could this shadow-like area explain the sightings?</em> Revised, see below.</p>
<p><strong>Edit</strong> First of all, it must be a rogue wave, <img src="http://i.stack.im... | g9121 | [
-0.009198044426739216,
0.05737191438674927,
-0.010720652528107166,
-0.02692648209631443,
0.080144964158535,
0.051552411168813705,
0.00579702015966177,
0.04252396896481514,
0.029739616438746452,
-0.009839975275099277,
0.01896732673048973,
0.01960364170372486,
0.05449456721544266,
0.04740136... |
<p>I am reading <a href="http://books.google.co.uk/books?id=Quv8awSN-RYC&printsec=frontcover&dq=magnetic%20techniques%20for%20the%20treatment%20of%20materials%20pdf&hl=en&sa=X&ei=ePKuUu2lH8yThQfs64D4CA&ved=0CDIQ6AEwAA#v=onepage&q&f=false" rel="nofollow">this</a> book, the part in particu... | g9122 | [
0.04621513932943344,
0.013236809521913528,
-0.030009714886546135,
-0.06052831560373306,
0.0751691609621048,
-0.013952082954347134,
0.029191914945840836,
0.0457148477435112,
-0.02784370630979538,
0.026025449857115746,
-0.06105593964457512,
0.08992158621549606,
0.019992932677268982,
-0.00519... |
<p>A black hole would radiate mass optimally for interstellar-travel applications in the range between $10^7$ and $10^8$ kilograms. Assuming a light-only radiation emission spectrum, with a parabolic reflector with efficiency $f$, this would create an acceleration</p>
<p>$$ a = \frac{f P}{mc}$$</p>
<p>$$ a = \frac{ f... | g9123 | [
0.015665872022509575,
0.055432457476854324,
0.0020551634952425957,
0.0013574324548244476,
0.0334995798766613,
-0.002185666700825095,
-0.02825886197388172,
0.025820119306445122,
-0.05639540031552315,
-0.017620444297790527,
0.05372701212763786,
0.0832066461443901,
-0.034558992832899094,
0.01... |
<p>The Klein-Gordan equation describing a spinless scalar field is one of the first things one studies in a QFT course, but there are no elementary spin-0 fields in nature.</p>
<p>Is the scalar field to QFT like the frictionless plane in high school physics, an aid to get us started?</p>
<p>Or is it deeper than that?... | g9124 | [
0.032852984964847565,
0.015451721847057343,
-0.0025242508854717016,
-0.048528026789426804,
0.0707632377743721,
0.004513869062066078,
0.03921861946582794,
0.013822377659380436,
0.02129231207072735,
-0.01194132212549448,
-0.0018956485437229276,
-0.031031230464577675,
0.027701176702976227,
-0... |
<p>Suppose I put water in a closed vessel and heat it, so the vessel becomes pressurized above ambient pressure. Now, there should be liquid and gaseous water inside the vessel. Since it's under pressure, when I open the vessel at the bottom, the liquid starts to flow out. If I wait until all liquid is expelled, and cl... | g9125 | [
-0.010760084725916386,
-0.03344900533556938,
0.009425889700651169,
0.02161138691008091,
-0.006026074290275574,
-0.0007251202478073537,
0.035597220063209534,
0.009587427601218224,
-0.04149257391691208,
0.00175213732291013,
-0.04785952344536781,
0.060033176094293594,
0.013299178332090378,
0.... |
<p>Since pH is a measure of the effective concentration of $\mathrm{H}^+$ ions a solution, I expect that an electric field applied to a solution will create a pH gradient. The higher concentration of $\mathrm{H}^+$ ions (corresponding to lower pH) should be close to the anion, and a lower concentration of $\mathrm{H}^+... | g9126 | [
-0.007374654524028301,
0.0008601655135862529,
0.00629293592646718,
-0.03802484646439552,
0.08807816356420517,
0.05347070097923279,
-0.05604744702577591,
0.027893653139472008,
-0.017849765717983246,
0.04880699887871742,
-0.08397001028060913,
0.01427349541336298,
0.010225806385278702,
-0.003... |
<p>A particle moving towards the origin has initial conditions $x(t=0) = 1$ and $\dot{x}(t=0)=0$</p>
<p>If the Lagrangian is L:=$\frac{m}{2}\dot{x}^2 -\frac{m}{2}ln|x|$ </p>
<p>This should satisfy Euler Lagrange Equation $$\frac{d}{dt} (\frac{\partial L}{\partial \dot{x}}) = \frac{\partial L}{\partial x}$$</p>
<p>Pr... | g9127 | [
0.081146739423275,
-0.026011234149336815,
0.0002927814202848822,
-0.08316685259342194,
0.046153996139764786,
0.006245901342481375,
0.05415262281894684,
-0.007843533530831337,
-0.06088988110423088,
-0.0012815063819289207,
-0.018744301050901413,
0.09198217839002609,
0.037542082369327545,
0.0... |
<p>how can we find out the effective mass of a hole,since a hole in the valence band is just an absence of electron?</p> | g9128 | [
-0.037938132882118225,
-0.02343321219086647,
0.002570348558947444,
-0.05103389918804169,
0.030920615419745445,
0.07188340276479721,
-0.012462911196053028,
0.02409796416759491,
0.0015696441987529397,
0.04923054203391075,
0.009735426865518093,
0.014323174022138119,
0.016710171476006508,
-0.0... |
<p>A book, <a href="http://rads.stackoverflow.com/amzn/click/0465060714" rel="nofollow">Exercises for the Feynman Lectures on Physics</a>, has recently been published. It consists of homework problems to provide practice with the techniques and concepts used in the famous Feynman lectures, which had not had published p... | g9129 | [
0.006914292927831411,
-0.012424007058143616,
-0.005842326674610376,
-0.014913372695446014,
0.043185632675886154,
0.04649945721030235,
0.0741802528500557,
-0.04637579619884491,
-0.06196840852499008,
0.008022317662835121,
0.024409210309386253,
0.05152620002627373,
-0.014900796115398407,
0.04... |
<p>I don't know much about string theory, apart from it being a theory of everything which brings QM, QED and nuclear forces and gravity under one single roof. I am curious to know from a mathematical view point, how the quantization of space-time is achieved in super string theory.</p> | g9130 | [
0.0250913817435503,
0.05337288975715637,
-0.013330685906112194,
0.021723849698901176,
0.03814030811190605,
0.011794102378189564,
-0.03899820148944855,
0.0019705675076693296,
0.004489806946367025,
-0.02858775109052658,
-0.059954967349767685,
0.020958296954631805,
0.0044125765562057495,
0.03... |
<p>I want to solve the transient heat equation on a ball. The boundary condition is the same over the hole outer surface. So this should reduce to a one-dimensional problem in radial direction. However I cannot use the one-dim heat equation, since the surface through which the heat flows goes quadratic with the radius.... | g9131 | [
0.037405963987112045,
-0.014110567979514599,
-0.011630765162408352,
-0.0354190319776535,
0.0007735015242360532,
-0.030568843707442284,
0.07681865990161896,
0.025585539638996124,
-0.03797631710767746,
0.014828658662736416,
-0.006250596605241299,
0.021368443965911865,
0.028069179505109787,
-... |
<p>You know energy is necessary for the occurrence of an event . Time is also exactly neccessary for the occurrence of an event. If there is no time , there will be no event. I mean time is a type of energy ?</p> | g9132 | [
0.04351605474948883,
0.0732196718454361,
0.02946590818464756,
-0.03907155618071556,
0.0035495846532285213,
-0.0036838501691818237,
0.00037773209623992443,
0.026095585897564888,
-0.06504525244235992,
-0.012034865096211433,
-0.021441325545310974,
-0.03418855369091034,
-0.043619658797979355,
... |
<p>I need to know which formulas and the step-by-step answers for the following physics questions:</p>
<blockquote>
<p><em>1. You throw a ball upward with an initial speed of 7.0 m/s, and it returns to your hand o.92 seconds later, ( assuming air resistance can be ignored).</em></p>
<ul>
<li><em>(a) What is t... | g9133 | [
0.05663900822401047,
0.03614677116274834,
-0.004726387560367584,
0.023778729140758514,
0.006325053051114082,
0.017413554713129997,
0.08402509242296219,
-0.012334859929978848,
-0.04215174913406372,
-0.00003974809078499675,
-0.06351888179779053,
0.050425928086042404,
0.07766933739185333,
-0.... |
<p>For light travelling in a medium with refractive index greater than one:</p>
<p>The "average" speed of light is slower than the speed of light in a vacuum. As far as I know, the instantaneous speed of light in a medium is equal to the speed of light in a vacuum.</p>
<p>Is this correct?</p>
<p>If so, is this becau... | g298 | [
0.03283695876598358,
0.02767794579267502,
-0.003156204940751195,
0.022261733189225197,
0.016867250204086304,
-0.016613254323601723,
-0.013139798305928707,
0.020773645490407944,
-0.023558953776955605,
0.013194005936384201,
0.05270928889513016,
0.004206540994346142,
0.005846637301146984,
0.0... |
<p>How can I convert my self-similar boundary layer solution that is a function of the nondimensional wall-normal coordinate $\eta$ to be a function of dimensional $y$? For instance, if I determine from my boundary layer solution that $\delta_{99}$ occurs at $\eta = 5$, for a given set of dimensional parameters how do ... | g9134 | [
0.037797242403030396,
-0.007178594823926687,
0.004669103771448135,
-0.029525546357035637,
0.059399668127298355,
-0.0008006713469512761,
0.055055197328329086,
-0.04990765079855919,
-0.10143382847309113,
0.018077507615089417,
0.005928167141973972,
0.015534774400293827,
0.015737853944301605,
... |
<p>I'm trying to make an orbit simulator, and I want to draw the orbit of a satellite given its position and velocity vectors in a 2-D plane. I found <a href="http://physics.stackexchange.com/questions/72203/calculating-specific-orbital-energy-semi-major-axis-and-orbital-period-of-an-o">this other question</a> which te... | g9135 | [
0.007918822579085827,
0.027729028835892677,
0.002880242420360446,
-0.05287864804267883,
-0.06200844421982765,
-0.02514982596039772,
0.004025086294859648,
-0.0013230860931798816,
-0.00034665557905100286,
-0.019891340285539627,
0.042159467935562134,
0.01048535667359829,
0.0918433740735054,
-... |
<p>I am a science fiction writer. </p>
<p>I know how to time travel to the future (using black hole or speed). But I need to argue in my novel that time travel to the past might not be possible. Is there a way to do this without using a formula? And how basic would argument look like ?</p> | g9136 | [
-0.010763110592961311,
0.04119378328323364,
0.016690848395228386,
-0.012657496146857738,
0.028577037155628204,
-0.01657164841890335,
-0.04104920104146004,
0.05898035690188408,
-0.08078248798847198,
0.02572629600763321,
0.09018544107675552,
0.011856939643621445,
0.0009607901447452605,
-0.00... |
<p>Can a semi-conductor ( germanium or silicon) or a semi-metal ( graphite ) carry an induced charge ?</p> | g9137 | [
0.011498358100652695,
0.042703840881586075,
0.0007424353971146047,
0.01542827021330595,
0.02946343645453453,
0.022689491510391235,
-0.035011474043130875,
-0.024755265563726425,
-0.0517239049077034,
0.02096366696059704,
-0.05307503789663315,
0.07061375677585602,
-0.08630640059709549,
-0.041... |
<p>Currently working on this question, however I'm not sure how to solve it. </p>
<blockquote>
<p>As a pendulum swings in simple harmonic motion at the surface of the Earth, the angle the pendulum makes relative to its equilibrium position is given by $\theta(t) = (0.140 \:\mathrm{rad})\cos(5.72t)$ where t is in se... | g9138 | [
0.08855239301919937,
0.033804092556238174,
0.013152344152331352,
-0.03686198592185974,
0.0460546538233757,
0.07333938777446747,
0.057841867208480835,
-0.039645176380872726,
-0.03838002681732178,
0.03864791616797447,
-0.05270528048276901,
0.035720132291316986,
-0.024894097819924355,
-0.0533... |
<p>Can someone provide a trigonometry/geometry insight to deduce the angle of the plane is the same as the angle of the component of the weight?</p>
<p><img src="http://i.stack.imgur.com/W5OfC.jpg" alt="enter image description here"></p> | g9139 | [
0.046895865350961685,
-0.04171554371714592,
0.005228789988905191,
-0.05598835647106171,
0.04049540311098099,
-0.001591831212863326,
0.04515073075890541,
0.0018960449378937483,
-0.05549241974949837,
0.02482229471206665,
0.004507862962782383,
-0.010181101970374584,
0.012669662944972515,
-0.0... |
<p>I'm supposed to shoot a projectile from the origin to a point $(x_0 , y_0)$ with minimal initial velocity $v_0$. (no air resistance; regular gravity)</p>
<p>The flight time should be $T=\frac{x_0}{v_x}$. Plugging in to the equation for y, I get
$$y_0=\frac{-g}{2}\frac{x_0^2}{v_x^2}+\frac{x_0v_y}{v_x}$$</p>
<p>Rec... | g9140 | [
0.041962191462516785,
-0.008216509595513344,
-0.026959072798490524,
0.04600444808602333,
0.0382629930973053,
-0.00947179738432169,
0.02119200862944126,
-0.02673555351793766,
-0.05133291333913803,
-0.0327715240418911,
-0.025512538850307465,
0.06544411182403564,
0.02232617512345314,
0.031085... |
<p>Inspired by the wording of <a href="http://physics.stackexchange.com/a/62847/10851">this answer</a>, a thought occurred to me. If a photon and a neutrino were to race along a significant stretch of our actual galaxy, which would win the race?</p>
<p>Now, neutrinos had better not be going faster than the speed of li... | g9141 | [
-0.029244650155305862,
0.056222494691610336,
0.02458156645298004,
0.033272258937358856,
0.02348642610013485,
-0.02881281077861786,
0.003971716854721308,
-0.0018378675449639559,
-0.014900538139045238,
-0.021621601656079292,
0.10012663900852203,
0.028417669236660004,
0.0030012920033186674,
-... |
<p>A human cannon has a spring constant of 35 000 N/m. The spring can be extended up to 4.5m. How far horizontally would a 65kg clown be fired if the cannon is pointed upward at 45 degrees to the horizontal?</p> | g9142 | [
0.03762947767972946,
0.004347082227468491,
0.014512596651911736,
0.009957830421626568,
-0.021580787375569344,
0.04699372127652168,
0.04839111119508743,
-0.039277419447898865,
-0.08261759579181671,
-0.046628307551145554,
-0.08966924995183945,
0.013466267846524715,
0.003055352019146085,
-0.0... |
<p>RCFT's (rational conformal field theories) in two dimension are very well-studied, but it seems that there is no any gravity dual of such theories has been found. Is there example of the holographic dual of RCFT?</p> | g9143 | [
0.060874417424201965,
0.02085770294070244,
0.021184628829360008,
-0.007409506477415562,
0.011825960129499435,
0.01390931662172079,
0.014999659731984138,
0.005838808137923479,
0.005384018179029226,
-0.055221084505319595,
0.046526748687028885,
-0.016175728291273117,
0.007651687134057283,
-0.... |
<ul>
<li><p>One can define the Poincare group as the group of isometries of the Minkowski space. Is its Lie algebra given either by the equations 2.4.12 to 2.4.14 (..as also given in this page - <a href="http://en.wikipedia.org/wiki">http://en.wikipedia.org/wiki</a>/Poincaré_group..) or equations 2.4.18 to 2.4.24 of We... | g9144 | [
-0.002580770757049322,
0.0018955200212076306,
-0.021809721365571022,
-0.016851942986249924,
0.024138297885656357,
-0.0037482117768377066,
0.07682200521230698,
0.02989109419286251,
0.009152651764452457,
0.05939899757504463,
-0.019304528832435608,
-0.04655536264181137,
-0.0388987697660923,
0... |
<p>Consider a charged spherical shell of radius $R$ and surface charge density $\sigma$. Choose a point on the surface of the shell and cut a spherical cap of radius $a \ll R$. What is the electric field intensity in the middle of the hole?</p>
<p>This was made up intended as a relatively easy problem to solve, it tur... | g9145 | [
0.028092289343476295,
-0.013859139755368233,
-0.0034667670261114836,
-0.027865994721651077,
0.03581078723073006,
0.032889723777770996,
0.05785538628697395,
-0.01405272912234068,
-0.020148567855358124,
0.06209677830338478,
-0.017301596701145172,
0.025254346430301666,
0.00801139511168003,
-0... |
<p>The Maxwell-Boltzmann velocity distribution in 3D space is
$$
f(v)dv = 4\pi \left(\frac{m}{2\pi k_B T}\right)^{3/2} v^2 \exp\left(-\frac{m v^2}{2k_B T}\right)dv$$
It gives the probability for a single particle to have a speed in the intervall $[v,v+dv]$. But this probability is not zero for speeds $v > c $ in co... | g9146 | [
0.05325569584965706,
0.03604253754019737,
0.0034937916789203882,
0.04871964082121849,
0.057874057441949844,
0.06469257175922394,
0.022554317489266396,
0.025239761918783188,
-0.04736555740237236,
-0.012886999174952507,
0.04667938873171806,
0.011188649572432041,
-0.0001103091926779598,
0.008... |
<p>I would like to know if there is some formula / graph which would provide / show the efficiency of a certain type of propeller in space. Specifically, I'm interested in the acceleration attainable at certain speeds.</p>
<p>I'm writing a science fiction book and I'm trying to make it as correct as possible, fact wis... | g9147 | [
0.010858015157282352,
0.11357639729976654,
0.012513931840658188,
-0.016200318932533264,
0.032821428030729294,
-0.037881143391132355,
0.005725486669689417,
0.02489496022462845,
-0.07884290814399719,
0.02976970747113228,
0.07306216657161713,
0.04356686398386955,
0.023960601538419724,
0.00286... |
<p>I watched some videos on the <a href="http://en.wikipedia.org/wiki/Unified_field_theory" rel="nofollow">unified field theory</a>, specifically interviews with Michio Kaku and John Hagelin, and want to learn a bit more about it. I looked up the theory of everything, string theory and unified field theory but most of ... | g9148 | [
0.010973665863275528,
0.08236123621463776,
-0.013764864765107632,
0.013075780123472214,
0.04428727924823761,
0.051225803792476654,
0.012914914637804031,
-0.00329653755761683,
0.008877121843397617,
-0.04960300028324127,
-0.03481864556670189,
-0.033191926777362823,
0.007214437238872051,
0.00... |
<p>Suppose there is a positron and an electron, and they both collide, and we get $E=2mc^2$ of energy from the collision. Now, the charge also got vanished. Now suppose, I create neutrinos from the collision's energy, which are neutral and that doesn't violate conservation of charge, now the mass-energy of the neutrino... | g9149 | [
0.05601327493786812,
-0.026493554934859276,
0.007374979089945555,
0.022296063601970673,
0.07352691888809204,
0.03804795444011688,
-0.07538717985153198,
0.03476223349571228,
-0.043407026678323746,
-0.01351450476795435,
0.009409068152308464,
-0.025916215032339096,
0.01309699472039938,
-0.020... |
<p>Say I have a rigid body in space. I've read that if I during some short time interval apply a force on the body at some point which is not in line with the center of mass, it would start rotating about an axis which is perpendicular to the force and which goes through the center of mass.</p>
<p>What is the proof of... | g9150 | [
0.06254568696022034,
0.01285445224493742,
0.01259526889771223,
0.011415119282901287,
0.02022036537528038,
0.009881431236863136,
0.05673760920763016,
0.019526846706867218,
0.0032606394961476326,
-0.011448840610682964,
-0.02350349724292755,
0.03381814807653427,
-0.008216574788093567,
-0.0144... |
<p>As far as I understand, the motivation for using representation theory in high energy physics is as follows. Assume that a theory has some (internal or external) symmetry group which acts on a vector space. Then fields satisfying the theory will have to transform under some representation of that symmetry group, by ... | g9151 | [
0.012584990821778774,
0.060280121862888336,
-0.016134269535541534,
-0.01863030157983303,
0.02545868419110775,
0.022029198706150055,
0.01926565356552601,
0.10236696153879166,
-0.061627812683582306,
-0.02259855531156063,
-0.006213207729160786,
-0.015823043882846832,
-0.023860741406679153,
-0... |
<p>I wonder if the refractive index of acetone, ethanol, methanol, heptane was measured in the range above 830 nm. The site <a href="http://refractiveindex.info" rel="nofollow">refractiveindex.info</a> provides it only for visible, and I couldn't find any other data so far.</p> | g9152 | [
-0.03429395332932472,
0.0011516190133988857,
0.007863050326704979,
-0.058483704924583435,
-0.044666826725006104,
0.012231430038809776,
-0.05359490215778351,
0.0024781657848507166,
0.01584552228450775,
0.03286771476268768,
0.03083016723394394,
-0.021670818328857422,
0.03463689610362053,
-0.... |
<p>Before asking, I swear that, for how it may seem strange, this is all true. Very briefly, when my pc is off and I am near it, it turns on. I do not touch anything. Nobody else have the same effect. I just have to still near it for 3-5 seconds and it will boot. It begun 1-2 weeks ago. The first time was at night, and... | g9153 | [
0.02004220150411129,
0.012367894873023033,
-0.011701610870659351,
0.01394735462963581,
0.005958794616162777,
0.05191453918814659,
0.01704278029501438,
0.017338886857032776,
-0.00031921619665808976,
-0.02374933660030365,
0.01264489721506834,
0.06478265672922134,
-0.03918939456343651,
-0.034... |
<p>I am currently busy with some magnetism and quite shockingly (to me at least) I haven't yet read anything about the difference between the north pole and the south pole of a magnet. Before I started with magnetism I learned electricity, here there 2 opposite charges: negative charges (electrons) and positive charges... | g9154 | [
0.030486421659588814,
0.0037804876919835806,
-0.021462813019752502,
-0.001311574480496347,
0.08128394931554794,
0.06405876576900482,
-0.029173308983445168,
0.02491915412247181,
-0.02506006881594658,
-0.0014880597591400146,
-0.014782464131712914,
0.010377825237810612,
0.02231832966208458,
0... |
<p>Why does Lagrangian of free particle depend on the square of the velocity ?
For example, $L(v^4)$ also doesn't depend on direction of $v$. </p> | g9155 | [
0.07397111505270004,
0.013125190511345863,
-0.004794086795300245,
-0.03672904148697853,
0.04319759085774422,
0.0042220368050038815,
0.06558399647474289,
-0.022238535806536674,
-0.029595714062452316,
-0.05854957178235054,
0.006635753437876701,
0.042918331921100616,
0.05877896025776863,
0.03... |
<p>My question is simple, when you have a small lump of sugar, it's hard to break it with your bare hands, but when you blow in it, it appears to be more easy. (it's a piece of advice i learned for my gran, and it works !)</p>
<p>Is it due to humidity of the breath? or the spacing between sugar cristals? or something ... | g9156 | [
0.07493382692337036,
0.059695858508348465,
-0.0198458731174469,
0.014361292123794556,
-0.029274018481373787,
0.0020494135096669197,
0.01474006101489067,
0.04122206196188927,
-0.018172994256019592,
-0.0198390893638134,
0.04870779439806938,
-0.04347364231944084,
0.020451845601201057,
0.03017... |
<p>What is wrong if I define temperature of a small system (I mean, a system which has not a large number of particles) by</p>
<p>$$1/T = dS/dE$$</p>
<p>?</p> | g9157 | [
0.06380663067102432,
0.039026547223329544,
-0.02413463220000267,
-0.0387917160987854,
-0.0034319665282964706,
0.02413596212863922,
-0.003591871587559581,
-0.00849499274045229,
-0.01757517084479332,
-0.04066232591867447,
0.007440158631652594,
0.06304001808166504,
0.03668631240725517,
0.0144... |
<p>In relation to this question:</p>
<p><a href="http://physics.stackexchange.com/questions/48574/how-can-a-black-hole-produce-sound">How can a black hole produce sound?</a></p>
<p>Which notes that the hole "produces" sound. The top answer states that:</p>
<blockquote>
<p>What you think of as the hard vacuum of ou... | g9158 | [
0.011005710810422897,
0.0251474492251873,
-0.0027167159132659435,
-0.019839875400066376,
0.05029319226741791,
0.06139834597706795,
-0.03346438705921173,
0.022297581657767296,
-0.004181483760476112,
-0.0674499124288559,
0.008526421152055264,
0.045281294733285904,
0.03852289915084839,
0.0234... |
<p>I am seeking references to the first articles regarding the observation of polaritons. </p> | g9159 | [
-0.00922668632119894,
0.017373932525515556,
0.0016867078375071287,
0.00401349738240242,
0.04402069374918938,
0.006621949840337038,
0.007119541056454182,
-0.00971317384392023,
0.024822749197483063,
-0.004996498115360737,
-0.02626090869307518,
-0.012903898023068905,
0.02788953296840191,
-0.0... |
<p>I am taking a course in Computer Graphics, and the teacher said we could put materials in there main categories:</p>
<ul>
<li>mirror like</li>
<li>glossy or specular</li>
<li>diffuse</li>
</ul>
<p>He suggested that the law of reflection is immutable and applies to all types of surfaces but that glossy and diffuse ... | g9160 | [
0.03608861193060875,
0.006742323283106089,
0.017644722014665604,
-0.04497918486595154,
0.08333762735128403,
0.08283215761184692,
0.04269902780652046,
0.04570680856704712,
0.0008156924741342664,
-0.023583363741636276,
0.023000216111540794,
0.047536130994558334,
0.04464356228709221,
-0.01082... |
<p>This is a know rule when baking: </p>
<blockquote>
<p>Don't open the oven until your cake is finished, otherwise it will "fall".</p>
</blockquote>
<p>Why/how does this happen?</p> | g9161 | [
0.06268848478794098,
0.06573603302240372,
0.010080726817250252,
0.01739630289375782,
-0.0009585926309227943,
-0.017011145129799843,
0.02882523648440838,
0.05364067479968071,
-0.01596575416624546,
-0.015316871926188469,
-0.05625825375318527,
0.035691998898983,
0.03339266777038574,
0.0380549... |
<p>As far as I understand, the basic reason why we are not able to solve QCD at low energies is because it is a strongly coupled quantum field theory, and a part from exceptional situations in simplified models (involving for instance supersymmetry), we have no tools to fully analyze such regimes. Correct me if I am wr... | g9162 | [
0.0833558514714241,
0.07162049412727356,
0.00789723265916109,
0.0228396225720644,
0.04075368493795395,
0.005651245359331369,
-0.001223457045853138,
-0.0004062121734023094,
-0.023786576464772224,
-0.06932327151298523,
0.011025996878743172,
-0.012245260179042816,
-0.029316432774066925,
0.000... |
<p>This question concerns the following exercise from an old exam:</p>
<blockquote>
<p>The vibrational motion of a linear diatomic molecule can be approximated as simple harmonic motion.</p>
<ul>
<li><p>A CO molecule has a bond with force constant $k = 1900 \, Nm^{-1}$. What frequency of radiation would excit... | g9163 | [
0.007721097208559513,
0.031526289880275726,
-0.0030797331128269434,
0.02888905629515648,
0.058605652302503586,
-0.0018585267243906856,
-0.003337692003697157,
0.037573423236608505,
-0.04048290476202965,
-0.003604267258197069,
-0.0008320008055306971,
0.008798480965197086,
0.004655984230339527,... |
<p>I am reading 't Hooft's notes on Black Holes. I want to find the solutions of the Klein-Gordon equation $(\tilde{x},\tilde{y}, \rho, \tau)$ in the Rindler coordinates which are $$x=\tilde{x}\,\,\,\,\ y= \tilde{y}\,\,\,\,\,\,z=\rho \cosh{\tau}\,\,\,\,\,t=\rho \sinh{\tau}$$.</p>
<p><img src="http://i.stack.imgur.com/... | g9164 | [
0.051753006875514984,
-0.008733537979424,
-0.010421784594655037,
-0.06817560642957687,
0.10390755534172058,
0.02208484522998333,
-0.009871349669992924,
0.005685159005224705,
-0.034427937120199203,
0.017486069351434708,
-0.023625973612070084,
-0.0010572168976068497,
-0.020902952179312706,
0... |
<p>In many theories of CMT, we assume the nature of quasi-particles (without giving proper justifications). For example, we assume nature of quasi-particles to be fermionic in case of a interacting fermion system we began with and impose anti-commutation relations accordingly. Like in BCS theory, while using the Bogoli... | g9165 | [
0.010248837992548943,
0.02719266526401043,
-0.010257400572299957,
-0.0413079634308815,
0.11595014482736588,
-0.04040305316448212,
0.022342879325151443,
0.025982031598687172,
0.01914631575345993,
-0.032253462821245193,
-0.06486427783966064,
0.0538875050842762,
-0.01429296750575304,
0.020828... |
<p>The specifics of a question I am working on are, "After a 0.280-kg rubber ball is dropped from a height of 1.80 m, it bounces off a concrete floor and rebounds to a height of 1.45 m."</p>
<p>Why doesn't the ball return to the same height?</p> | g9166 | [
0.08184411376714706,
-0.0002647392393555492,
0.013857124373316765,
0.036613356322050095,
0.04794023558497429,
0.05031877011060715,
0.06558294594287872,
0.0038988336455076933,
-0.05518703907728195,
-0.05021956190466881,
-0.03950471431016922,
0.01394415833055973,
0.04043560475111008,
-0.0132... |
<p>I've been working on a project that involves thermoacoustics, and one of the commonly-used values in this field is know as the thermal penetration depth. It is calculated as follows:</p>
<p>$$\delta_k = \sqrt{2K / (C_p 2 \pi f \rho)}$$</p>
<p>where $K$ is the thermal conductivity of the fluid in question (heli... | g9167 | [
0.03460013121366501,
0.014598585665225983,
-0.013076355680823326,
-0.0845303013920784,
0.02754114381968975,
0.03908289968967438,
0.017670851200819016,
0.014478103257715702,
-0.060428522527217865,
0.008486736565828323,
-0.005293622147291899,
0.014878146350383759,
-0.014642002061009407,
0.01... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.