question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Suppose we have a symmetric wavefunction that composed of a two-particle system:</p>
<p>$$ \psi_s = \frac{1}{\sqrt 2} \left(|u,A\rangle|v,B\rangle + |v,A\rangle|u,B\rangle\right)$$</p>
<p>where $u_{(x)}$ and $v_{(x)}$ are wavefunctions corresponding to orthonormal bound states u and v.</p>
<p>Can I assume that th... | g9639 | [
-0.015819771215319633,
-0.05364018306136131,
-0.004367913119494915,
-0.03284626826643944,
0.022688260301947594,
0.018096676096320152,
-0.018165625631809235,
-0.02318922057747841,
0.008943569846451283,
0.027627117931842804,
0.023475924506783485,
0.0285175833851099,
-0.0027647409588098526,
-... |
<p>I was looking at a plot of the parton distribution functions today and had a question. On the y axis, it seems like the value of x f(x) for gluons is greater than one at small x. I was under the impression that parton distribution functions are probability densities and cannot be greater than one. Also, x is a fract... | g9640 | [
0.06764928251504898,
0.031707894057035446,
-0.0030396608635783195,
-0.04926981031894684,
0.02124478667974472,
0.02916477620601654,
0.021672796458005905,
0.010914057493209839,
-0.04876885190606117,
-0.0452289953827858,
-0.02858906239271164,
-0.036694444715976715,
0.028313711285591125,
-0.01... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://physics.stackexchange.com/questions/9290/why-does-the-moon-drift-away-from-earth">Why does the moon drift away from earth?</a> </p>
</blockquote>
<p>It seems to me that, due to conservation of energy, the moon would drift away from the Ear... | g221 | [
0.07137063145637512,
0.019810065627098083,
0.01576695404946804,
0.045244038105010986,
0.002009894698858261,
0.048448510468006134,
0.03698123246431351,
0.021452149376273155,
-0.009721685200929642,
-0.06269252300262451,
0.0012623161310330033,
0.0018459042767062783,
0.006024266593158245,
-0.0... |
<p>I was curious if antimatter could undergo nuclear fission/fusion with other antimatter. It makes sense, I was wondering if it would work?</p> | g9641 | [
0.009841123595833778,
0.026354316622018814,
0.0522250160574913,
0.03270624577999115,
0.009231784380972385,
-0.014236193150281906,
-0.10209809988737106,
0.05714906007051468,
-0.018444953486323357,
-0.037245042622089386,
0.011699671857059002,
0.006840670481324196,
0.005402942653745413,
-0.02... |
<p>Is the inflation speed of the universe accelerating or is it a constant speed of expansion proportional to distance between objects.</p> | g9642 | [
0.02939632721245289,
0.06372833997011185,
0.02578926458954811,
0.008129753172397614,
-0.031335994601249695,
0.04000122472643852,
-0.021142641082406044,
0.011025249026715755,
-0.025527162477374077,
-0.031196273863315582,
0.06261657923460007,
0.010456305928528309,
-0.02042543701827526,
-0.02... |
<p>I'm confused by the famous wave-particle duality mystery:</p>
<p>When a particle is left unobserved, it acts like a wave and can explore all classically available particle trajectories simultaneously. By looking at it, you force it to decide on a single trajectory, like going through the left or right slit, or like... | g9643 | [
0.03875692933797836,
0.022041836753487587,
0.019048957154154778,
0.00854400172829628,
0.08776011317968369,
0.06823442876338959,
0.03486951068043709,
0.0315011627972126,
0.059892430901527405,
-0.04414813593029976,
0.023518366739153862,
0.0005595452967099845,
0.05688140168786049,
0.056220389... |
<p>Although the question stands for itself, I would like to know that if the answer has to be no then does any particular law forbids the existence of such forces; and if there are such forces then what are these and upon travelling under such forces in a closed loop where does the energy come from (as they are non con... | g9644 | [
0.02400699444115162,
0.014439767226576805,
0.016964709386229515,
-0.003033442422747612,
0.05271390452980995,
0.021235819905996323,
0.004229078069329262,
0.0030520614236593246,
-0.01415788009762764,
-0.0350935198366642,
-0.02526438795030117,
-0.02369225025177002,
-0.04731801524758339,
-0.01... |
<p><strong>Chaos</strong> is defined as an aperiodic long-termed behavior, that is very sensitive to initial conditions.</p>
<p>Now from this definition I can only conclude that the adjective 'chaos' is a <em>mere analogy</em>, since there is nothing aperiodic (or periodic) during inflation. The inflaton follows a nic... | g9645 | [
0.07268465310335159,
0.010037112049758434,
0.022854700684547424,
-0.006291723810136318,
0.000012698518730758224,
-0.019861778244376183,
0.021519862115383148,
-0.020225906744599342,
0.0335167720913887,
-0.00447734585031867,
0.019788406789302826,
0.0524991974234581,
0.007261751219630241,
0.0... |
<p>When studying supersymmetry breaking, people often use a spurion chiral superfield to study the soft SUSY breaking terms which enter the Lagrangian ($X=\theta^2 F$). Since we let the spurion couple to every field and assume that the messengers are at the Planck scale this is used to parametrize gravity mediated SUSY... | g9646 | [
0.004874958656728268,
0.033189088106155396,
-0.0033684715162962675,
-0.02177516557276249,
0.014185450971126556,
-0.037206992506980896,
-0.017939545214176178,
0.006219515111297369,
-0.028595641255378723,
-0.01246193889528513,
-0.017504695802927017,
-0.007792861200869083,
0.015325235202908516,... |
<p>The question goes like this:
If we push a body shortly uphill and it gets a starting velocity of $v \ ms^{-1}$,the coefficient of friction between the body and the surface is constant, represented by $k$, . Which graph shows the movement of the body correctly?</p>
<p>The answer on the back of the book is a graph th... | g9647 | [
0.07360798120498657,
0.04201731085777283,
0.013574817217886448,
0.033591125160455704,
0.04625704139471054,
0.005536437500268221,
0.08147712796926498,
-0.004231492523103952,
-0.03587907925248146,
-0.02370024286210537,
-0.0039154342375695705,
0.03727739676833153,
0.03826090320944786,
0.01360... |
<p>I have recently come to know that the electric and magnetic field contain both the translational and angular momenta in it given by some particular formulas at any given instant of the space....But I don't understand how? PLEASE EXPLAIN.....
Is it related to photons being emitted by the accelerating charges or with ... | g9648 | [
0.04199722036719322,
0.00026837020413950086,
-0.014942039735615253,
-0.019028013572096825,
0.09168388694524765,
0.021059736609458923,
0.007275354582816362,
0.02065194956958294,
-0.01776726171374321,
0.018812039867043495,
-0.037553876638412476,
0.0028070879634469748,
0.026915762573480606,
-... |
<p>Was reported <a href="http://xxx.lanl.gov/abs/1208.3829">here</a>. Of course if this is real it is very exciting. It leads me to the question: given that it took so long to find this resonance at a meager 38 MeV, is it possible that all SUSY particles are hiding down in the MeV or KeV range (or lower)?</p> | g9649 | [
0.035038866102695465,
0.005619465373456478,
0.00676357327029109,
-0.00048202407197095454,
0.011036187410354614,
0.019774911925196648,
-0.05211516469717026,
0.02574993669986725,
0.0016302054282277822,
-0.02322288416326046,
-0.028056954964995384,
0.006062421016395092,
-0.004884188994765282,
... |
<p>The question is about <strong>experiments</strong> (and references) that demonstrate interference patterns of neutral (chargless) particles (fermions), especially neutrons.</p>
<p>Like <strong>double-slit experiments for neutrons</strong> (or equivalent).</p>
<p>Searching around did not yield sth (or maybe i did n... | g9650 | [
0.018771206960082054,
0.05313678830862045,
0.035036444664001465,
-0.04714742675423622,
0.014947561547160149,
-0.00044545752461999655,
-0.008418409153819084,
0.03969395533204079,
0.03055192530155182,
-0.025109535083174706,
-0.006328966468572617,
0.051172275096178055,
-0.013787669129669666,
... |
<p>Dirac argues on page 17 of his book, The Principles of Quantum Mechanics, that multiplication of a ket by a complex number shouldn't change the state this ket represents. But then concludes:</p>
<blockquote>
<p>Thus a state is represented by the direction of a ket vector, and any
length one may assign to the ke... | g9651 | [
-0.007696262560784817,
0.006110113579779863,
-0.0031923085916787386,
-0.03134598955512047,
-0.0338570810854435,
0.006774256471544504,
0.04365875944495201,
0.039953358471393585,
-0.0057716770097613335,
-0.0580831877887249,
-0.015644272789359093,
-0.0476880706846714,
0.037741001695394516,
0.... |
<p>I'm looking for existing papers studying a variation to Einstein equation that does not rely on the annoying matter conservation identity:</p>
<p>$$ T_{\mu \nu; \nu} = 0 $$</p>
<p>And instead tries to equate the divergence-free Einstein tensor with a sum of $T_{\mu \nu}$ plus some gravitational energy tensor $Y_{\... | g9652 | [
0.008722756057977676,
0.023372497409582138,
-0.0024656117893755436,
-0.02427861839532852,
-0.008424429222941399,
-0.01028511580079794,
0.008357224054634571,
0.011992557905614376,
-0.04650796204805374,
-0.010187404230237007,
-0.006491245701909065,
-0.04297802597284317,
0.03457192704081535,
... |
<p>I'm having trouble with the explanation that a standing wave in a string is the superposition of traveling waves.</p>
<p><img src="http://www.physicsclassroom.com/Class/waves/u10l4c5.gif" alt="standing wave"></p>
<p>The nodes in the diagram above are points where the particles of the string's medium undergo zero d... | g9653 | [
0.03543718159198761,
0.025101127102971077,
-0.020541299134492874,
-0.036474984139204025,
0.0836939737200737,
0.02990330010652542,
0.05175993964076042,
0.05253623053431511,
-0.020208727568387985,
-0.03586824983358383,
-0.03912057727575302,
-0.012376002967357635,
-0.033920686691999435,
-0.05... |
<p>I'm having some trouble finding an expression for the probability to find the particle outside the classical area in the harmonic oscillator.</p>
<p>I have a wavefunction defined as:</p>
<p>$\psi \left( x,\,t \right)=\frac{1}{2}\left( \sqrt{3}i{{\phi }_{1}}\left( x \right){{e}^{-i{{E}_{1}}t/\hbar }}+{{\phi }_{3}}\... | g9654 | [
0.013652284629642963,
0.021457666531205177,
-0.01898062974214554,
-0.07565944641828537,
0.010122358798980713,
0.011118643917143345,
0.03572328761219978,
0.04668828472495079,
-0.04192173108458519,
0.008650627918541431,
-0.004897258710116148,
0.048330944031476974,
-0.04162781313061714,
-0.00... |
<p>The planetary motion equations are written in the ellipse equation format, i.e. $x^2/a + y^2/b = 1$.</p>
<p>Can anyone please tell me where I can find the list of all the planetary motion equations, (Mercury, Venus, Mars, Earth, and so on) in the form of $(x(t)-c)^2/a + (y(t)-d)^2/b = 1$? (Both $x$ and $y$ are func... | g9655 | [
0.03982718661427498,
0.05902557075023651,
-0.008265385404229164,
0.031700536608695984,
0.08243519812822342,
-0.025943797081708908,
0.03959979489445686,
-0.05522145330905914,
0.004930706229060888,
0.014831780456006527,
-0.03389223664999008,
0.016599219292402267,
0.05583440512418747,
-0.0199... |
<p>Is there a simple way to understand why phonon-phonon-interaction is described by higher order terms in the potential?</p>
<p>I mean: Having a quadratic potential is essential for the definition of the phonons as excitations of an harmonic oscillator. How can you suddenly talk about (interacting) phonons when you d... | g9656 | [
0.0875445231795311,
0.060362234711647034,
0.017453989014029503,
-0.0014243134064599872,
0.07899734377861023,
-0.03179902210831642,
-0.03696737065911293,
-0.014345426112413406,
0.008707953616976738,
-0.012555570341646671,
-0.05853300914168358,
0.0014060725225135684,
0.01707461103796959,
0.0... |
<blockquote>
<p><em>A compound flywheel is to be constructed in the form of a circular disc with a radius of 0.25m, a thickness of 0.05m and a moment of inertia about its axis of 2Kgm2. the flywheel is to have a central circular disc of aluminium alloy, density 2800kgm-3, and a steel outer rim, density 7900kgm-3. den... | g9657 | [
0.02886025421321392,
0.021163923665881157,
-0.002229896141216159,
-0.013623880222439766,
0.051629532128572464,
-0.03412623703479767,
0.06332133710384369,
-0.012400357984006405,
-0.06325308233499527,
-0.007585668005049229,
-0.04309339448809624,
-0.00464423093944788,
-0.005884597543627024,
-... |
<p>In <a href="http://www.youtube.com/watch?v=BcLk7jEQfx0" rel="nofollow">this</a>, in my opinion, intriguing speech, Rupert Sheldrake, tells the story of the drop between the measured valued of $c$ in 1928 and 1945. When he goes to visit the Head of Metrology of the Physics Lab in Teddington, he says (I resume):</p>
... | g9658 | [
0.0379175990819931,
0.008381349965929985,
-0.015126482583582401,
-0.06082089990377426,
0.09507431834936142,
0.04375503584742546,
0.06802033632993698,
-0.007189738564193249,
-0.05398891866207123,
-0.024933822453022003,
-0.007577965967357159,
0.04061487317085266,
-0.02737491950392723,
0.0384... |
<p>I've noticed that if you take a full glass of water and look from above, through the water, you can't see through the glass sides - instead, you see a reflection. I tried with a laser pointer and the case was the same, the beam was just reflected from the water-glass interface. Even when looking from a variety of an... | g9659 | [
-0.006282385438680649,
0.03128907084465027,
0.0028627333231270313,
0.02073357254266739,
-0.025124922394752502,
0.003516663331538439,
0.05527567118406296,
0.007640817668288946,
-0.008217828348279,
-0.02301567792892456,
0.06888113170862198,
0.0421602725982666,
0.018361900001764297,
-0.016632... |
<p>In the paper <em>Markov Fields</em> by Edward Nelson the introduction section claims that analytically continuing a Markov process with appropriate symmetry properties yields the solution of the Schrodinger equation. </p>
<p>What is the appropriate symmetry required by a Markov process to solve the Schrodinger equa... | g9660 | [
0.0037015294656157494,
0.00008820138464216143,
-0.014435072429478168,
-0.02116655558347702,
0.01819007471203804,
0.004828132688999176,
0.051608528941869736,
0.07038215547800064,
-0.016261126846075058,
-0.017299022525548935,
-0.0016869239043444395,
-0.00433306721970439,
-0.012266418896615505,... |
<p>Roughly speaking, in condensed matter systems, spin waves and spin density waves are both low-energy states with spin that varies spatially. What precisely are their differences?</p> | g9661 | [
-0.00866662710905075,
-0.003902916330844164,
-0.00839226320385933,
0.045142825692892075,
0.04306945204734802,
0.025691037997603416,
0.0008952912176027894,
-0.004470241256058216,
0.02751229517161846,
-0.03805533051490784,
0.0219586081802845,
0.011838830076158047,
0.027457259595394135,
-0.06... |
<p>From a statistical mechanics point of view, the <em>extensivity</em> of thermodynamics arises from the fact that we can neglect interaction terms in the Hamiltonian. This allows us to infer that when we put two systems in contact, the total energy is approximately equal to the sum of the individual systems' energy. ... | g9662 | [
-0.007659712340682745,
0.05791834369301796,
-0.0006670551374554634,
-0.05359479784965515,
-0.021282926201820374,
-0.04303773120045662,
-0.02799185737967491,
0.04101324826478958,
0.002387384884059429,
0.025876762345433235,
-0.01900777779519558,
-0.014773114584386349,
-0.04074929282069206,
0... |
<p>I have been trying to reason why energy packets (i.e. <a href="http://en.wikipedia.org/wiki/Photon">photons</a>) are assumed to be quantized. I know this originated from Max Planck, but may someone explain why energy couldn't be emitted continuously rather than in packets?</p>
<p>Also:</p>
<p>Planck said he didn't... | g9663 | [
0.05648917704820633,
0.005133213009685278,
-0.006674152798950672,
0.008624516427516937,
0.032829441130161285,
0.02743261493742466,
-0.001989159034565091,
0.09265848994255066,
-0.038431037217378616,
-0.0426488071680069,
0.012128347530961037,
0.027213994413614273,
-0.0038166663143783808,
0.0... |
<p>Events in relativity[SR or GR]are marked by coordinate values and not by physical values.We write a metric for motion along the x-axis:
$$ds^2=g_{00}dt^2-g_{11}dx^2$$ ----------- (1)</p>
<p>For physical values we may write:</p>
<p>$$ds^2=dT^2-dL^2$$ ------------ (2)</p>
<p>Where $dT^2=g_{00}dt^2$ and $dL^2=g_{11}... | g9664 | [
0.03044736385345459,
0.024217139929533005,
-0.028285861015319824,
-0.040789250284433365,
0.050588831305503845,
-0.013543837703764439,
0.04736071079969406,
0.003895106725394726,
-0.010739046148955822,
-0.05043863505125046,
0.04701242595911026,
0.039995647966861725,
0.07615239918231964,
-0.0... |
<p>In popularizations, people tunnel through walls or doors. But what can really tunnel through a graphene sheet without tearing it? </p>
<p>According to Wikipedia, a single layer of graphene absorbs 2.3 % of white light, but 97% makes it through. It conducts electrons well enough to make a transistor. </p>
<p>I ... | g9665 | [
0.02035875990986824,
0.09853504598140717,
0.012780731543898582,
0.015293750911951065,
0.07090961933135986,
0.0018854797817766666,
-0.000988710206001997,
-0.02018916793167591,
-0.021604854613542557,
-0.005806661210954189,
-0.0030132352840155363,
-0.004836583510041237,
0.002454395405948162,
... |
<p><img src="http://img696.imageshack.us/img696/7078/gaussl.jpg" alt="">!</p>
<p>Why does it say that the flux due to q_2 and q_3 through S is 0? Doesn't it contain a nonzero charge q_1? </p>
<p>Does anyone also know the difference between "no charge" vs "net charge is 0"? My book differentiates it.</p> | g9666 | [
0.06329435855150223,
-0.03157177194952965,
-0.02911689132452011,
0.010515567846596241,
0.1028066873550415,
0.04314609244465828,
0.053128812462091446,
-0.007568166125565767,
-0.05178928002715111,
-0.011477000080049038,
-0.05207330361008644,
0.022119298577308655,
0.02683248743414879,
0.01427... |
<p>While answering <a href="http://physics.stackexchange.com/a/71912/6634">another question</a> about heat in an atom, the discussion in the comments led to the question of how heat is related to thermal radiation picked up by infrared cameras. The answer is that molecules undergoing translational motion (which therefo... | g9667 | [
0.03693250194191933,
0.04365001618862152,
-0.011238189414143562,
0.04531347006559372,
0.013240218162536621,
0.007535974960774183,
-0.006817208137363195,
0.06674496829509735,
-0.03365609049797058,
0.01375189982354641,
-0.009831331670284271,
0.02411101758480072,
0.058393001556396484,
-0.0254... |
<p>When a charged particle moves in an electric field, the field performs work on the particle. Thus, the energy of the field decreases, turning into kinetic energy of the particle.</p>
<p>Does the magnetic field of a permanent magnetic similarly lose energy and perform work when moving a conductor with a current?</p> | g9668 | [
0.04443522170186043,
0.007011952344328165,
0.0005047869053669274,
0.012053004465997219,
0.046049728989601135,
0.00949834194034338,
0.01462916936725378,
0.029426373541355133,
-0.04108237847685814,
0.008224591612815857,
-0.038508474826812744,
0.016992133110761642,
-0.05033748596906662,
-0.04... |
<p>Minkowski space time is defined in terms of a flat pseudo-Riemannian manifold. I have wondered if it can be redefined as Riamannian manifold and in the case what type of curvature would there appear.</p>
<p>Formally:</p>
<p>Let M be a semi-Riemannian manifold of dimension 4, corresponding to the Minkowski space, a... | g9669 | [
0.03334660083055496,
-0.001010444015264511,
0.004044886212795973,
-0.017834538593888283,
0.02230083756148815,
-0.004066816531121731,
0.039252180606126785,
-0.012096637859940529,
0.0049554938450455666,
0.022094422951340675,
-0.041658077389001846,
0.009679165668785572,
0.026971546933054924,
... |
<p>Currently working through a practice preliminary examination problem. I have your standard charge situated a distance d from a infinite conductor(lets say in the $\hat{z}$ direction and neglecting gravity). The question asks when $v = 0$ at $t = 0$, determine the equation of motion of the electron.</p>
<p>We know t... | g9670 | [
0.04266183078289032,
0.013076224364340305,
-0.006792260333895683,
-0.015363174490630627,
0.06297273188829422,
0.024724755436182022,
0.056088387966156006,
0.02606654353439808,
-0.057295672595500946,
-0.009581437334418297,
-0.05488502234220505,
0.06261106580495834,
0.018432097509503365,
-0.0... |
<p>If the physical world we know is made of matter stretched in time and space and some forces affecting it, what would be an Idea, pure Information or something similar.</p>
<p>Does those things don't exist in a physical model or did I just miss something.</p>
<p>If yes where to arrange it into the physical model? I... | g9671 | [
0.01609666459262371,
-0.004529441706836224,
0.0070557245053350925,
-0.038511067628860474,
0.05646223947405815,
0.06574234366416931,
-0.05838557705283165,
0.0036885393783450127,
-0.05566893517971039,
-0.04981549084186554,
0.0987701267004013,
-0.06219399720430374,
0.019316529855132103,
0.012... |
<p>I am trying to figure out how an object could achieve a perfectly circular orbit. Given a mass for the planet or other body the object is orbiting and a distance from the center of mass, how fast would the object have to be moving perpendicular to the center of mass?</p>
<p>My initial assumption was it would have ... | g9672 | [
0.035300616174936295,
0.05824274197220802,
0.01886872388422489,
0.00595470704138279,
0.03149857372045517,
0.02082347869873047,
0.031006038188934326,
0.03761598840355873,
-0.03788640350103378,
-0.019430609419941902,
-0.0001545161649119109,
0.03543505445122719,
0.07810353487730026,
-0.034582... |
<p>I was pointed out by a friend to <a href="http://hint.fm/wind/" rel="nofollow">this website</a> that shows live map of wind in US. It sometimes show interesting places where <a href="http://imgur.com/yEOjS" rel="nofollow">all the wind seems to converge and vanish</a>. </p>
<p>What's the origin of such "wind drains"... | g9673 | [
0.09727000445127487,
0.014182457700371742,
-0.032680146396160126,
0.014036725275218487,
0.03709965944290161,
0.055485598742961884,
0.047951363027095795,
0.040941957384347916,
-0.043103206902742386,
-0.014195091091096401,
-0.008555160835385323,
-0.0011947943130508065,
0.06795753538608551,
0... |
<p>I've read that QM operates in a Hilbert space (where the state functions live). I don't know if its meaningful to ask such a question, what are the answers to an analogous questions on GR and Newtonian gravity?</p> | g9674 | [
-0.0028271349146962166,
0.01841241493821144,
0.00121691869571805,
-0.01807480677962303,
0.012912224046885967,
0.014403056353330612,
0.04915932938456535,
-0.03143959492444992,
-0.028619434684515,
-0.019056133925914764,
-0.04231494665145874,
-0.025531591847538948,
0.03171328827738762,
0.0056... |
<p>Is dark matter really a form of matter? We know it has a gravitional attraction and we know that everything that has a gravitional force is made by matter. But maybe this is an exception? </p>
<p>And if there are such theories, would there be theories on that dark energy is not really energy?</p> | g9675 | [
0.055577896535396576,
0.004886590410023928,
0.03124260902404785,
-0.04887048900127411,
0.018022986128926277,
0.018434923142194748,
-0.10151730477809906,
-0.030936485156416893,
-0.026474297046661377,
-0.056807540357112885,
0.05715830624103546,
-0.02030743844807148,
-0.013765444047749043,
-0... |
<p>In what ways can energy transform into matter and vice versa? Annihilation is one way to tranform matter to energy. Fission is another (when splitting and atom, what happens to its two parts?)</p>
<p>Are quantum fluctuations one way to transform energy to matter?</p> | g9676 | [
0.02645714022219181,
0.01756388694047928,
0.008614206686615944,
-0.02770141512155533,
0.05787435546517372,
0.018170516937971115,
-0.08069154620170593,
0.03531835973262787,
-0.025939637795090675,
0.009902785532176495,
-0.0013452694984152913,
-0.02258620411157608,
0.007964115589857101,
-0.02... |
<p>If I have two containers filled with very hot water(~210F) with one in outer space and one on earth, which one has a higher rate of cooling initially? Imagine the containers are single wall metal containers that are able to withstand any pressure.</p>
<p>Intuitively I would assume the one in space would cool faster... | g9677 | [
0.0689949318766594,
0.01375886332243681,
0.024799255654215813,
0.05705275759100914,
-0.018031084910035133,
0.03391844779253006,
-0.02764074131846428,
0.02413884736597538,
-0.04122578352689743,
-0.012339807115495205,
0.02977011166512966,
0.04375827684998512,
0.044879596680402756,
0.01152775... |
<p>Imagine a bullet fired at a series of partitions stacked one after the other. Given that the bullet looses half its velocity in crossing each partition, velocity of the same is a geometric progression(GP) with $a= v_0$ and $r=0.5$.</p>
<p>The question is, how many partitions is it supposed to successfully cross, or... | g9678 | [
0.044968895614147186,
-0.013027871027588844,
0.021458785980939865,
-0.007981519214808941,
-0.008865567855536938,
-0.013738200068473816,
0.06846556812524796,
0.01353740319609642,
-0.08610899746417999,
0.026985684409737587,
-0.03159177303314209,
-0.016020316630601883,
-0.0005432862089946866,
... |
<p>Someone claiming to have studied physics is telling me that spacetime is all that exists and that this fact is the basis of modern physics. When I said matter/energy also exists in its various forms, he said that energy is merely spacetime "waving/vibrating/acting", else what did I think was doing the waving: magica... | g804 | [
0.022638900205492973,
0.050737082958221436,
0.014761339873075485,
-0.013632742688059807,
0.012904349714517593,
0.07469809800386429,
-0.021474501118063927,
-0.004750439897179604,
0.014215091243386269,
-0.034473974257707596,
0.07552804797887802,
-0.045956000685691833,
0.0031963412184268236,
... |
<blockquote>
<p>Starting with the Boltzmann equation in terms of $f(t,\vec v,\vec x)$ or $f(t,\vec v)$</p>
<p><a href="http://en.wikipedia.org/wiki/Boltzmann_equation" rel="nofollow">http://en.wikipedia.org/wiki/Boltzmann_equation</a></p>
<p>$$\left(\frac{\partial}{\partial t} + \vec{v} \, \nabla_\vec{x} + ... | g9679 | [
0.06506608426570892,
-0.019878162071108818,
-0.00042165175545960665,
-0.024617105722427368,
0.04372474551200867,
-0.036824967712163925,
0.02272747829556465,
-0.009348386898636818,
-0.06964725255966187,
-0.01628831960260868,
-0.033607762306928635,
0.011067608371376991,
0.014712749049067497,
... |
<p>Can I use Newtonian laws of dynamics and kinematics applied to electrons (like $F = ma$ and $s = s_0 + v_0 t + at^2/2$)? If not, why not? </p>
<p>I know that everything in principle behaves in a quantum way, even macroscopic bodies, but is the level of precision of using classical mechanical on electrons acceptable... | g9680 | [
-0.015747852623462677,
-0.003744568908587098,
0.005395705811679363,
0.056168995797634125,
0.023742573335766792,
-0.03933111950755119,
-0.028289977461099625,
0.029165329411625862,
0.0244703721255064,
0.03674405440688133,
0.0177475456148386,
-0.013625933788716793,
0.01356816291809082,
-0.017... |
<p>In the context of the 3 + 1 decomposition of spacetime needed for a Hamiltionian formulation of general relativity, quantities with so called internal indices are introduced (in the <a href="http://rads.stackoverflow.com/amzn/click/0199590753" rel="nofollow">book</a> I am reading on p.43). For such quatities $G^i$ ,... | g9681 | [
0.005915920715779066,
0.012755815871059895,
-0.041152991354465485,
-0.019973795861005783,
-0.0027189278043806553,
0.055244408547878265,
0.09462887793779373,
0.006331532262265682,
-0.025027379393577576,
0.02858741208910942,
-0.006005740724503994,
-0.003204768756404519,
0.06731007248163223,
... |
<p>Consider some positive charge that is distributed uniformly over a very long line along the z-axis.</p>
<p>If I am stationary with respect to the line then there is only static electric field which has cylindrical symmetry.</p>
<p>Assume now that I am moving with some constant velocity which has only a (positive) ... | g9682 | [
0.07065144181251526,
-0.013930747285485268,
-0.012200937606394291,
0.012112938798964024,
0.05748564004898071,
0.00889651570469141,
0.06997513025999069,
0.006346299313008785,
-0.055918511003255844,
-0.02054070122539997,
-0.027958214282989502,
-0.01135579589754343,
-0.05732446908950806,
-0.0... |
<p>In lectures on effective field theory the professor wanted to find the correction to the four point vertex in massless $\phi^4$ theory by calculating the diagram,</p>
<p>$\hspace{6cm}$<img src="http://i.stack.imgur.com/JmHzE.png" alt="enter image description here"></p>
<p>We consider the zero external momentum lim... | g9683 | [
0.022307846695184708,
-0.014066428877413273,
0.006169148255139589,
-0.03196824714541435,
0.04897413030266762,
0.06178303062915802,
0.043978989124298096,
0.0292600616812706,
-0.03357791528105736,
0.03938264027237892,
-0.010706804692745209,
0.015907902270555496,
-0.015452958643436432,
-0.022... |
<p>I usually don't want to do this, but please go to this link, the solution is too big to post it here</p>
<p><a href="http://engineering.union.edu/~curreyj/MER-201_files/Exam2_2_26_09_Solution.pdf" rel="nofollow">http://engineering.union.edu/~curreyj/MER-201_files/Exam2_2_26_09_Solution.pdf</a> </p>
<p>And go to pa... | g9684 | [
0.0805484801530838,
-0.011003722436726093,
0.004991235211491585,
-0.001570520456880331,
0.05259416624903679,
-0.008564023301005363,
0.07428207248449326,
-0.007101002614945173,
-0.03718622028827667,
0.01838628202676773,
-0.017325205728411674,
0.025980867445468903,
0.01894986443221569,
-0.00... |
<p>What is a <a href="http://en.wikipedia.org/wiki/Ergodic_theory" rel="nofollow">ergodic</a> system? What is Onset temperature of <a href="http://en.wikipedia.org/wiki/Ergodicity" rel="nofollow">ergodicity</a> breaking in super cooled liquids when we go towards lower temperature?</p> | g9685 | [
0.09102663397789001,
0.03630831092596054,
-0.04423848167061806,
-0.03153320774435997,
0.023746252059936523,
0.041834715753793716,
0.030000023543834686,
0.046720802783966064,
-0.03925199434161186,
0.003750162199139595,
-0.06678326427936554,
0.058265320956707,
0.021584533154964447,
0.0237088... |
<p>Why is allowed decompose the spacetime metric into a spatial part + temporal part like this for example</p>
<p>$$ds^2 ~=~ (-N^2 + N_aN^a)dt^2 + 2N_adtdx^a + q_{ab}dx^adx^b$$ </p>
<p>($N$ is called lapse, $N_a$ is the shift vector and $q_{ab}$ is the spatial part of the metric.)</p>
<p>in order to arrive at a Hami... | g9686 | [
0.030909990891814232,
-0.011029859073460102,
-0.03491956740617752,
-0.05197423696517944,
0.0005401610396802425,
0.0248409453779459,
0.08587398380041122,
0.006536595523357391,
-0.09101143479347229,
-0.0019713910296559334,
0.024437256157398224,
0.02054326981306076,
0.014097068458795547,
0.03... |
<p>How is the <a href="http://en.wikipedia.org/wiki/Schr%C3%B6dinger_equation" rel="nofollow">Schrödinger equation</a> </p>
<p>$$\frac {\partial }{\partial t}\psi=-\frac {i }{\hbar }H{\psi }$$</p>
<p>being derived?</p> | g9687 | [
0.02303663268685341,
-0.020036056637763977,
-0.035516053438186646,
-0.017979521304368973,
0.05558411777019501,
0.006570687051862478,
0.05008624494075775,
0.0500347837805748,
-0.04606824740767479,
-0.03423864394426346,
0.01057168934494257,
-0.03957528993487358,
-0.005025271791964769,
0.0147... |
<p>How to find the average value of several measurement results if we know their statistical and systematics uncertainties?
There might be that there is no such thing as best way to do it, but it would be helpful to know how is this done in different areas of physics/science.</p> | g9688 | [
0.00489012198522687,
-0.014812356792390347,
-0.02885846607387066,
0.01008742768317461,
0.02227124571800232,
-0.02096826583147049,
0.010915782302618027,
0.01625252328813076,
-0.02138856053352356,
-0.03380000963807106,
-0.006437688134610653,
-0.0023747480008751154,
0.0302579365670681,
-0.001... |
<p>I think it was Feynman that suggested that you should always carry ten big problems around in your head, and when you encounter a new method, see whether this new method allows you to make progress on any of your problems. To prevent the answers becoming to unwieldy, I'll restrict the question here to condensed matt... | g9689 | [
0.00010722634760895744,
0.05768778920173645,
0.042288850992918015,
-0.004204212687909603,
0.012603353708982468,
-0.0163394957780838,
0.0356789268553257,
0.020238038152456284,
-0.022528670728206635,
0.0008515029912814498,
0.003437759354710579,
-0.023808475583791733,
-0.01705865189433098,
-0... |
<p>I am modelling gas combustion in porous media. Most contemporary models assume that the pressure drop from the porous media is small enough to disregard, but I want to include that in my investigation. Most studies alos assume that the gas is filtered through the media at a constant speed $u$.</p>
<p>I use Darcy's ... | g9690 | [
0.03233307600021362,
-0.02486611157655716,
-0.002994012786075473,
0.015368965454399586,
0.05233767256140709,
0.004628163296729326,
-0.02618238516151905,
0.03751523047685623,
-0.04222995787858963,
-0.02547973394393921,
0.039764825254678726,
-0.024229630827903748,
0.03913624584674835,
0.0099... |
<p>My understanding is that gravitomagnetism is essentially the same relativistic effect as magnetism. If so, why is it that I've heard so much about magnetic monopoles, but never gravitomagnetic monopoles? Aren't each just as theoretically well-motivated as the other? In a similar vein, one always hears that "there is... | g648 | [
0.026063356548547745,
0.08183521777391434,
0.0023400045465677977,
-0.009730808436870575,
0.04731152206659317,
0.06922770291566849,
-0.03664281591773033,
0.02802533656358719,
0.03857464715838432,
-0.002433410845696926,
-0.005112124141305685,
-0.0057365428656339645,
0.015251649543642998,
-0.... |
<p>When a quantum system have a double degenerescence at one point, the Hamiltonian should be proportional to Pauli matrices near this point (also known as <em>diabolic point</em>) [<a href="http://ajp.aapt.org/resource/1/ajpias/v78/i7/p661_s1?isAuthorized=no" rel="nofollow">Ref.</a>]. But, why the Hamiltonian have thi... | g9691 | [
0.02919418178498745,
0.004543612711131573,
-0.026101963594555855,
-0.025543151423335075,
0.07703381776809692,
0.0166074987500906,
0.06146417558193207,
0.009115568362176418,
-0.00994135718792677,
0.0035958627704530954,
-0.03423844650387764,
0.05412555858492851,
0.034219153225421906,
0.02823... |
<p>Is it possible to get two atoms to opposite quantum states of one another so when I change the state of first one, the state of the other one changes too? Is it possible to move them to another place on Earth and communicate like this? I've seen it in a sci-fi game but am wondering if that is truly possible. </p> | g9692 | [
-0.05479453131556511,
0.02317027933895588,
0.030662238597869873,
-0.008790186606347561,
0.04741211235523224,
0.0014865651028230786,
-0.08944395184516907,
0.023194974288344383,
0.0038916668854653835,
0.05280041694641113,
-0.01637095957994461,
0.025431016460061073,
0.0008763801888562739,
-0.... |
<p>I was pondering about the following 'experiment', and was curious about the formulae behind it. </p>
<p>Imagine having a glass filled with a liquid. On one side there is a sensitive receiver that records all the vibrations and is attached to the outside. If I would then tap on the opposite side I would in send an i... | g9693 | [
0.03052823431789875,
-0.00356677477248013,
0.0037554556038230658,
-0.038370225578546524,
0.04902142286300659,
-0.04602384939789772,
0.029691530391573906,
0.02633383870124817,
-0.010980474762618542,
-0.05951772257685661,
-0.04268796369433403,
0.03286679461598396,
0.04590808227658272,
0.0594... |
<p>$:\!\!\hat\phi(x)^2\!\!:$, for example, constructed from the real Klein-Gordon quantum field.</p>
<p>For a Wightman field, the Wightman function $\left<0\right|\hat\phi(x)\hat\phi(y)\left|0\right>$ is a distribution, which is certainly the case for the real Klein-Gordon quantum field --- call it $C(x-y)$ in t... | g9694 | [
-0.0011484830174595118,
-0.0024067177437245846,
0.01690262369811535,
-0.10366228222846985,
0.02246924489736557,
-0.014445023611187935,
0.04639521986246109,
-0.00637879129499197,
0.00616321200504899,
-0.023752562701702118,
-0.062395695596933365,
0.041418734937906265,
-0.010838903486728668,
... |
<p>In classical Newtonian mechanics, from what I understand, conservation of energy stems from the fact that all known forces are conservative forces,
and vector calculus tells us that they can be represented by a potential energy function.</p>
<p>I understand how Energy Conservation is derived by Noether's theorem, b... | g9695 | [
0.04264643043279648,
-0.033475250005722046,
0.007859554141759872,
0.025455698370933533,
-0.019811108708381653,
0.0007502008229494095,
0.044386494904756546,
0.05071903392672539,
-0.06893622875213623,
0.01656590960919857,
-0.016792893409729004,
-0.054548442363739014,
-0.026208974421024323,
-... |
<p>I am teaching myself Differential Equations from a website. In the website I am up to Direction Fields and an example of a differential equation is Newton's Second Law of Motion. It is written on the website like this:</p>
<p>$$m\frac{dv}{dt}=mg-\gamma v$$</p>
<p>I know that $m$ is the mass, $g$ is the gravitation... | g9696 | [
0.04489266127347946,
0.01180345844477415,
-0.020687883719801903,
-0.0400085486471653,
0.08272146433591843,
0.024886438623070717,
0.049486517906188965,
-0.011010219343006611,
-0.09561147540807724,
-0.024261178448796272,
-0.01884089969098568,
0.00282219797372818,
0.08637206256389618,
-0.0252... |
<p>I was wondering how gravity would behave on object of different shapes.</p>
<ol>
<li><p>If the Earth was squeezed into a thin disk what would the gravitional acceleration be at the center of the flat surface? Would it be really low because the amount of matter beneath me would be small? If I stood on the edge would... | g313 | [
0.06408428400754929,
0.06059063598513603,
-0.00010724949243012816,
-0.03587736561894417,
0.040299657732248306,
0.08186342567205429,
-0.029478099197149277,
-0.0054817795753479,
-0.10680209845304489,
-0.08252366632223129,
0.0025580653455108404,
-0.024876484647393227,
0.05137842893600464,
0.0... |
<p>I have a talk tomorrow in which <a href="http://en.wikipedia.org/wiki/Detailed_balance">detailed balance</a> is needed and I don't want to bore my audience with elaborate explanations for it so I'm looking for simpler explanations.</p>
<p>As far as I understood it detailed balance means, that for any given time the... | g9697 | [
0.01482381485402584,
0.021217379719018936,
-0.02426825277507305,
0.007321178913116455,
0.029745174571871758,
0.008428569883108139,
0.09020144492387772,
-0.003927755635231733,
0.020886028185486794,
-0.05325687304139137,
-0.04451552778482437,
-0.0352957621216774,
0.059006474912166595,
0.0182... |
<p>usually when people want to quantize the string on flat background, they will try to find the the OPE of embeddings (by solving a green function in a 2D space) and use them to find the energy-momentum tensor OPE, central charge, Virasoro modes and their algebra and then, covariant quantization. </p>
<p>BUT
on a cur... | g9698 | [
0.02707507647573948,
-0.025376716628670692,
-0.0049645621329545975,
-0.054124776273965836,
0.025769067928195,
0.05110038444399834,
0.050907202064991,
-0.02993960864841938,
-0.08717553317546844,
0.023086542263627052,
-0.012230673804879189,
0.014292054809629917,
0.0319327749311924,
0.0004210... |
<p>I'm interested in teaching myself quantum mechanics, and I'm looking for a good goal to aim for. </p>
<p>I've got an undergrad maths degree and a graduate degree in probability theory and stochastic processes. I've worked fairly extensively with diffusion processes, so I understand how the Fokker-Planck equation wo... | g98 | [
-0.017530139535665512,
-0.010959362611174583,
0.013613682240247726,
-0.04328267648816109,
-0.03318106010556221,
-0.0188766922801733,
0.015481311827898026,
-0.007835371419787407,
0.011694371700286865,
-0.018145641312003136,
0.027557849884033203,
0.02700459212064743,
0.036703500896692276,
-0... |
<p>In a crystal, we don't have full translational symmetry, but we still have discrete translations. This allows us to define "crystal momentum" that is conserved modulo a reciprocal lattice vector.</p>
<p>In a crystal, we don't have full rotational symmetry, but we still have discrete 2, 3, 4, and/or 6-fold rotation... | g9699 | [
0.00270455633290112,
0.037991899996995926,
0.01814921200275421,
-0.025787003338336945,
0.016289928928017616,
-0.06310877203941345,
0.009223117493093014,
0.0279880128800869,
0.027626659721136093,
-0.030210450291633606,
-0.03838789090514183,
-0.012470652349293232,
-0.01962456852197647,
-0.09... |
<p>If a star is 1 billion light years away, it means that the light we see from the star is emmitted billions of years ago.</p>
<p>How does this light not undergo a frequency change or get damped inspite of the collosal distance of travel? I am asking this as doppler effect is used to know star-distances and is one of... | g9700 | [
0.022050684317946434,
0.033324990421533585,
-0.01604646071791649,
0.009385189041495323,
0.041056420654058456,
0.07930769771337509,
0.006685755681246519,
0.037964124232530594,
-0.0024895542301237583,
-0.018244372680783272,
-0.0018943052273243666,
0.04851548746228218,
0.06274678558111191,
0.... |
<p>I recently came across a question, for which I saw two possible methods of finding the solution. I was required to calculate the "current flowing" $I$ when given the voltage $V$, frequency $f$, total resistance $R$ and impedance of the circuit $Z$. In the book that these questions were written, there were two method... | g9701 | [
0.06203709542751312,
-0.05655759572982788,
-0.007459654938429594,
-0.05242946371436119,
0.057429295033216476,
-0.02440829575061798,
0.08831414580345154,
-0.039889391511678696,
-0.01985767111182213,
-0.006502716336399317,
-0.029244326055049896,
0.05977076292037964,
0.0026330563705414534,
0.... |
<p>If a small black hole (say about .1 mm radius or 1% of Earth's mass) came flying along at the speed of a comet or higher and impacted the earth, what would happen? Would it pass through the earth (and atmosphere) with minimal damage? Would it leave a crater (entry or exit?) Would it create a big enough shock wave to... | g885 | [
0.0017406020779162645,
0.009923751465976238,
0.03431946784257889,
0.012877186760306358,
-0.02554072067141533,
0.04935503005981445,
-0.0028420512098819017,
-0.014422528445720673,
-0.004240233916789293,
-0.04356760159134865,
0.032992273569107056,
0.02981705218553543,
0.027953479439020157,
-0... |
<p>Hello everybody I am kind of struggling with an assignment question related to general relativity. I am just going to type what the question is and explain what I am having trouble with: </p>
<p>Consider an electromagnetic plane wave in Minkowski space. We assume that in stationary coordinates $(t,x,y,z)$ the wave ... | g9702 | [
0.0019765745382755995,
-0.027931654825806618,
-0.02398095093667507,
-0.013164234347641468,
0.047169700264930725,
0.0355127677321434,
0.09646748006343842,
0.0581246055662632,
-0.04262298345565796,
0.017716696485877037,
0.03246891871094704,
0.0005189749062992632,
0.0032928644213825464,
0.021... |
<p>Can anyone explain to me what is actually "curved" when we speak of a Berry Curvature?</p> | g9703 | [
0.03333583474159241,
-0.003925764001905918,
0.0005525014130398631,
0.02083054557442665,
0.04788750782608986,
0.026152964681386948,
0.0005781514337286353,
-0.01738007739186287,
0.023195959627628326,
0.001890124287456274,
-0.02465103007853031,
0.017957644537091255,
0.08988669514656067,
-0.03... |
<p>Is a quantum system necessary if we want to generate true random sequence? The mathematical framework used for classical mechanics doesn't involve any random value. But the mathematical framework of quantum mechanics involves randomness by definition. Can we argue based on these information that a true random number... | g9704 | [
-0.014355692081153393,
0.016708146780729294,
0.011006164364516735,
-0.03570979833602905,
-0.036737605929374695,
0.021949097514152527,
0.009821545332670212,
0.035568155348300934,
0.009656427428126335,
-0.03681406378746033,
-0.02115444839000702,
-0.04944879934191704,
-0.047509267926216125,
0... |
<p>I am reading this very interesting paper:
<a href="http://m.iopscience.iop.org/1751-8121/41/40/402002/pdf/1751-8121_41_40_402002.pdf" rel="nofollow">http://m.iopscience.iop.org/1751-8121/41/40/402002/pdf/1751-8121_41_40_402002.pdf</a> about thermodynamics of channels in information theory.</p>
<p>More generally, es... | g9705 | [
0.01641310192644596,
-0.004193072207272053,
0.002284427871927619,
-0.04222944751381874,
0.025984521955251694,
-0.029966754838824272,
-0.03957018628716469,
0.04298259690403938,
-0.0319557748734951,
0.022077331319451332,
0.03454156965017319,
0.0009056006092578173,
-0.012264822609722614,
-0.0... |
<p>I have a simple question, can you spin a <a href="http://en.wikipedia.org/wiki/Conical_pendulum" rel="nofollow">conical pendulum</a> fast enough so that it rotates at 90 degrees?</p>
<p>The equation is $\tan(\theta)=v^2/rg$ , but at 90 degrees, $\tan(\theta)=\infty$ ... so what does this mean? Please provide suppor... | g9706 | [
0.027088109403848648,
0.02627459727227688,
-0.014761168509721756,
-0.03088267333805561,
0.07837589085102081,
-0.02842669188976288,
0.08692340552806854,
-0.03169132024049759,
-0.00667881965637207,
-0.014381593093276024,
-0.07239322364330292,
0.03338199481368065,
0.03407514840364456,
-0.0703... |
<p>One of the great unsolved problems in physics is <a href="http://en.wikipedia.org/wiki/Turbulence">turbulence</a> but I'm not too clear what the mystery is. Does it mean that the Navier-Stokes equations don't have any turbulent phenomena even if we solve it computationally? Or does it mean we simply don't have a clo... | g9707 | [
0.021343894302845,
0.07438161224126816,
0.020490087568759918,
-0.018547574058175087,
0.07533419132232666,
-0.031745411455631256,
0.04998626559972763,
0.020190885290503502,
-0.012380827218294144,
-0.09286634624004364,
-0.013971968553960323,
-0.03316173702478409,
0.017541391775012016,
0.0088... |
<p>There's a mechanism by which the southern ocean sequesters carbon from the atmosphere. It happens when strong winds displace a large slab of surface water, accumulating in a specific region where the localised excess water in the surface layer gets injected downward into the ocean's interior. This makes the ocean's ... | g9708 | [
0.0446181483566761,
0.012443159706890583,
-0.007347347680479288,
0.01597435772418976,
0.03734857589006424,
0.04681713506579399,
0.031133849173784256,
0.05435473844408989,
-0.02608710713684559,
-0.009952221997082233,
0.021538423374295235,
-0.026245225220918655,
0.06263091415166855,
0.030324... |
<p>A vector in one dimension has only one component. Can we consider it as a scalar at the same time?</p>
<p>Why time is not a vector, although it can be negative and positive (when solving for time the kinematics equation for example)?</p> | g9709 | [
0.03575610741972923,
0.012437112629413605,
0.002713886322453618,
0.013945573940873146,
0.016373811289668083,
-0.0030934943351894617,
0.05031765252351761,
-0.009640551172196865,
-0.0679333508014679,
0.012896975502371788,
0.041909221559762955,
-0.014207507483661175,
-0.023034697398543358,
0.... |
<p>please i want to ask when induced current produced by changing magnetic field according to faraday's law is this current DC or AC current ?</p> | g9710 | [
0.029885228723287582,
-0.02911512553691864,
0.00837187934666872,
-0.05488911271095276,
0.04195442050695419,
0.012678252533078194,
0.028085384517908096,
-0.00779681745916605,
-0.016380324959754944,
0.0030717134941369295,
-0.0532597191631794,
0.044251181185245514,
0.02672920934855938,
0.0070... |
<p>I'm currently working on an underwater robot and was hoping to use the gas bubbles for buoyancy control .</p> | g9711 | [
-0.006839650683104992,
0.01692359708249569,
0.01719151809811592,
0.025570761412382126,
0.019553236663341522,
0.05473412945866585,
-0.00810858141630888,
-0.011787677183747292,
-0.03416775166988373,
-0.08020133525133133,
0.017139187082648277,
0.02324606664478779,
0.026178739964962006,
-0.007... |
<p>Assume a central body of mass $M$, and call $a$ the acceleration of a test
body at a distance $r$ due to any interaction whatsoever with the central
body. Is is correct to say that the ratio $a r^2/ M$, for any interaction, is always larger than or equal to the gravitational constant $G$?</p> | g9712 | [
0.06614629924297333,
0.025457272306084633,
0.003557446878403425,
0.0010332398815080523,
-0.005765354260802269,
0.04060940816998482,
0.028144747018814087,
0.0038329269737005234,
-0.05604347214102745,
0.02234501764178276,
0.01657872274518013,
0.0056528677232563496,
-0.01940823160111904,
-0.0... |
<p>Can the fact that energy is distributed homogeneously in the universe be explained through heat flow and not the Cosmic Microwave Background(or in other words, can we say CMB is a result of heat flow and not the universe expanding from a singularity)?</p> | g9713 | [
0.09837540984153748,
0.025471486151218414,
-0.001415828475728631,
0.003551393747329712,
-0.012598342262208462,
0.041548844426870346,
0.00853474996984005,
0.04366253688931465,
0.011126349680125713,
-0.06853504478931427,
0.03689670190215111,
0.003738833824172616,
0.019364599138498306,
0.0737... |
<p>Is it possible to "extract" energy from a magnet, making it lose its magnetism? Or, to put in another way, is magnetism a form of energy? (I am not talking about potential energy in a magnetic field). Since matter is equivalent to energy, is the property of magnetism equivalent as well?</p> | g9714 | [
0.0435391329228878,
-0.0036892450880259275,
0.02194845862686634,
-0.029351653531193733,
0.027659239247441292,
-0.010793167166411877,
-0.06539056450128555,
0.03131404519081116,
-0.03373536840081215,
0.030571432784199715,
-0.0067701213993132114,
-0.007850621826946735,
-0.012443357147276402,
... |
<p>I had a college student build an overclocked PC using phase-change technology. (This is essentially an air-conditioning unit with the evaporator attached directly to the motherboard.) He said that cold temperature made the CPU more stable at higher clock speeds (5.5 GHz) by affecting how the atoms and electrons be... | g9715 | [
0.055246997624635696,
0.023809177801012993,
0.023411517962813377,
-0.004358944483101368,
0.02749665081501007,
-0.020650967955589294,
-0.0043351538479328156,
-0.008740801364183426,
0.012506670318543911,
0.010021126829087734,
-0.022394275292754173,
0.07812082767486572,
-0.048488788306713104,
... |
<p>So I wanted to find out how to (simply, if that's possible) derive the formula for a period of spring pendulum: $T=2\pi \sqrt{\frac{m}{k}}$. However, Google doesn't help me here as all I see is the ready-to-bake formula. Could you please point me some directions?</p> | g9716 | [
0.0652833804488182,
0.016040919348597527,
-0.006881614215672016,
-0.010246584191918373,
-0.010296322405338287,
-0.01720573566854,
0.05046256631612778,
-0.012833244167268276,
0.008054212667047977,
0.0005198423168621957,
-0.08613430708646774,
0.030506744980812073,
0.04579602926969528,
-0.004... |
<p>Consider a pendulum of length $h$ with a bob of mass $m$ it is held horizontally at and angle of $90^{\circ}$ with the vertical. A rod of mass $M$ and length $h$ is pivoted at its upper end and this pivot coincides with the point of suspension of the pendulum. The rod hangs downwards along the vertical. The pendulum... | g9717 | [
0.04668918624520302,
0.023050181567668915,
-0.008538144640624523,
-0.04122475907206535,
0.0382845401763916,
0.02213500626385212,
0.08107727766036987,
-0.0035291151143610477,
-0.05509045720100403,
0.06062888354063034,
-0.013834546320140362,
0.017471810802817345,
-0.023616615682840347,
-0.05... |
<p>The Heisenberg Uncertainty Principle suggests that the more precisely the position of a particle is measured, the less precisely its momentum can be known, and vice versa. </p>
<p>$$\sigma_x \sigma_p \geq \frac{\hbar}{2}$$</p>
<p>What I've read is that in order to measure the position of a particle accurately, we ... | g471 | [
0.03461601585149765,
0.03226221352815628,
-0.00909070298075676,
0.0012333757476881146,
0.05659840255975723,
0.06550096720457077,
0.05551266297698021,
0.09801753610372543,
-0.009649264626204967,
-0.03376300260424614,
-0.009347966872155666,
-0.061878751963377,
-0.038371648639440536,
0.017613... |
<p>I have this problem: I have a capacitor formed by two parallel square-shaped plates, of side $a$, and with distance $d$ between them. They're asking me out of other things, the magnetic force as a function of some things. I calculate de magnetic force by calculating the gradient of the magnetic energy, given by:</p>... | g9718 | [
0.02615388296544552,
0.06748440116643906,
-0.002454070607200265,
-0.04398727789521217,
0.016308166086673737,
0.014723125845193863,
0.020884530618786812,
0.005315898451954126,
-0.053148750215768814,
0.008419458754360676,
-0.07808548957109451,
0.0434536449611187,
-0.01820875145494938,
0.0134... |
<p>What is the nature of <strong>nuclear energy</strong>? This is closely related to the correct explanation of mass defect.</p>
<p>I did some research of that topic and cannot come to a single comprehensive and consistent description.</p>
<p>Below are related statements I gathered or can think of, describing the pro... | g671 | [
0.018685653805732727,
0.027705086395144463,
-0.005697246640920639,
0.006636211182922125,
0.033872298896312714,
0.03816970810294151,
-0.037721436470746994,
0.061840519309043884,
-0.037402234971523285,
-0.06475457549095154,
0.019442906603217125,
0.00325581943616271,
0.0018018033588305116,
0.... |
<p>As I understand it, the twin paradox was integral to Einstein's conclusion that nothing can travel faster than the speed of light. </p>
<p>Why wasn't there a similar conclusion for a hypothetical scenario where 2 blind musicians play the trumpet whilst moving away from each other at a speed close to the speed of so... | g9719 | [
0.04322493076324463,
0.05205337703227997,
0.0248621366918087,
-0.030461087822914124,
-0.006986221764236689,
0.056858569383621216,
0.02780570462346077,
-0.0022270982153713703,
-0.031461428850889206,
-0.03551575168967247,
0.0244158748537302,
0.008359096944332123,
0.04444215074181557,
0.02680... |
<p>Is there a systematic procedure for obtaining a deconfined theory from an s-confining theory (as defined in hep-th/9610139 for example)?</p> | g9720 | [
0.002557740081101656,
0.018279321491718292,
-0.0008837715722620487,
-0.02330057881772518,
-0.012094248086214066,
-0.0644952580332756,
0.009024892933666706,
0.01624443754553795,
-0.04249704256653786,
0.030225582420825958,
-0.039543621242046356,
-0.004663144238293171,
0.03096756339073181,
0.... |
<p>The question I'm about to pose is from a physics book I had recently bought. Since I am very interested in physics I am quite keen in understanding how this question can be solved. Before I present this question, I would like to explain the context in which this question was posed. It is a question related to the ch... | g9721 | [
0.0600176565349102,
0.02645180933177471,
-0.004650798160582781,
-0.003209196962416172,
-0.00652948347851634,
0.06207574903964996,
0.08524147421121597,
-0.0014604642055928707,
-0.046600475907325745,
-0.0172810610383749,
-0.0510224923491478,
0.02793300710618496,
-0.01113552413880825,
0.03853... |
<p>If we have an <strong>isolated</strong> system $Sb$ with thermodynamic entropy $Eb=X$
(and growing by the 2nd law of thermodynamics),</p>
<p>we could define an abstract system $Sa$ (containing the system $Sb$) but define the possible microstates as a single bit, being 1 (one) when $Eb>=X$, and 0 (zero) when $Eb... | g9722 | [
-0.005023302510380745,
0.034103572368621826,
-0.0019701598212122917,
0.013425740413367748,
-0.01871001161634922,
0.01096084900200367,
-0.04166748374700546,
0.01591545343399048,
-0.024925250560045242,
-0.06584721803665161,
-0.08332152664661407,
0.036718644201755524,
0.031193459406495094,
0.... |
<ol>
<li><p>If Ricci scalar describes the full spacetime curvature, then what do we mean by $k=0,+1,-1$ being flat, positive and negative curved space? </p></li>
<li><p>Is $k$ special version of a constant "3d-Ricci" scalar? </p></li>
<li><p>What is the difference between the local and global spacetime curvature?</p></... | g9723 | [
0.06168708577752113,
-0.0033358754590153694,
-0.043410029262304306,
0.013677646405994892,
0.00022581750818062574,
0.07268038392066956,
0.03867940232157707,
0.02691458724439144,
-0.05274495482444763,
0.014967788010835648,
0.01413812581449747,
0.006151377223432064,
0.0546024814248085,
-0.004... |
<p>An observer stands 3 m from speaker A and 5 m from speaker B. Both speakers, oscillating in phase, produce waves with a frequency of 250 Hz. The speed of sound in air is 340 m/s. What is the phase difference between the waves from A and B at the observer's location?</p>
<p>$$v=fλ\\ λ=1.36m\\ \\ Δr=|{ r }_{ 2 }-{ r ... | g9724 | [
0.025090107694268227,
-0.021548602730035782,
0.012605788186192513,
0.005542144179344177,
0.04797230288386345,
-0.01095576025545597,
0.06582695990800858,
0.001858570147305727,
-0.046964749693870544,
-0.007313563022762537,
-0.02327762357890606,
0.019615331664681435,
-0.08831530064344406,
0.0... |
<p>The <a href="http://en.wikipedia.org/wiki/Hydrogen_spectral_series" rel="nofollow">hydrogen spectral series</a> is given by the Rydberg formula: </p>
<blockquote>
<p>The energy differences between levels in the Bohr model, and hence the
wavelengths of emitted/absorbed photons, is given by the Rydberg
formula:... | g9725 | [
-0.03648841008543968,
-0.004881477449089289,
0.008835185319185257,
-0.009558362886309624,
-0.01116100512444973,
0.019139375537633896,
-0.0312805138528347,
0.030414888635277748,
-0.04642317816615105,
0.01982487365603447,
-0.01867705211043358,
0.06677687913179398,
0.010235981084406376,
0.049... |
<p>When the wavefunction of a particle is not an eigenfunction of an operator, the property to which the operator corresponds does not have a definite value, Why?
Also consider a linear combination of basis functions:
$$\psi=c_1\psi_1+c_2\psi_2+...=\sum_kc_k\psi_k$$
When the momentum is measured, in a single observatio... | g9726 | [
0.04978637024760246,
0.010647445917129517,
-0.004803508520126343,
-0.03662976250052452,
0.06584452837705612,
0.032879527658224106,
0.08486071974039078,
0.05550306290388107,
-0.017620081081986427,
-0.06107283756136894,
-0.043066758662462234,
-0.06531676650047302,
0.013577905483543873,
0.056... |
<p>Photons are packets of electromagnetic radiation (wave), what about other particles? Are other particles, say electrons, really just packets of waves?</p> | g304 | [
0.015162874013185501,
0.04625672101974487,
0.021737392991781235,
-0.006308595184236765,
0.05268831178545952,
0.012584395706653595,
-0.017578279599547386,
0.02202276885509491,
0.0467316210269928,
-0.03613191097974777,
0.03413025662302971,
0.03662840276956558,
0.012202496640384197,
0.0211032... |
<p>One can hear some sounds when boiling water, and usually the sound is loud initially, then it becomes quieter. When the water is about to boil, the sound starts to be louder again. Also, one may notice the pitch of the sound varies. Can anyone explain this phenomenon? Thank you!</p> | g314 | [
0.04109380394220352,
-0.015511252917349339,
-0.0015570514369755983,
0.021099848672747612,
0.033405136317014694,
0.005940681789070368,
0.013986720703542233,
0.03918900340795517,
-0.010930689051747322,
-0.03433039039373398,
-0.07374422997236252,
0.019075704738497734,
0.05335478484630585,
0.0... |
<p><strong>Assumption:</strong> Cell-phones generate some degree of electro-magnetic radiation. Whether it's harmful or not is not the question here.</p>
<p><strong>Claim:</strong> Certain devices may "neutralize" this radiation. (Ex: <a href="http://www.giawellness.com/2/products/terra-gia/cell-guard/" rel="nofoll... | g9727 | [
0.02309083193540573,
0.02406645379960537,
-0.00219168933108449,
0.030899062752723694,
0.052160631865262985,
-0.008802998811006546,
-0.016817402094602585,
0.03862952068448067,
0.021486252546310425,
-0.01379143912345171,
0.015609371475875378,
0.04467072710394859,
0.022435616701841354,
0.0127... |
<p>I'm wondering if there's any simple way to define and solve for a null cone for a general spacetime geometry in $n+1$ dimensions, given its vertex $p^\mu$. I can't seem to find a simple way to do it that doesn't involve solving for null geodesics. It seems like it's something that should be in a lot of GR textbooks,... | g9728 | [
0.03165049105882645,
0.03255731612443924,
0.0019922435749322176,
-0.04827716574072838,
0.010750534944236279,
-0.013668402098119259,
0.02018817886710167,
-0.08505465090274811,
-0.03057878278195858,
-0.038329873234033585,
0.03418838232755661,
-0.03252895176410675,
0.0876610055565834,
0.01762... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.