question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Schrödinger’s cat, the thought experiment, makes it seem like as if measurement can cause a system to stop being in a superposition of states and become either one of the states (collapsed).</p>
<p>So does a system always exist in a superposition? In this sense, do things in the macroscopic world have a wavefunctio... | g9447 | [
-0.02195848524570465,
0.03579692542552948,
0.015136819332838058,
-0.05993391200900078,
0.04954669624567032,
0.03760162368416786,
-0.01282996591180563,
0.04781254753470421,
-0.01644546538591385,
-0.041170068085193634,
-0.02599232643842697,
-0.06397354602813721,
0.03750299662351608,
0.048234... |
<p>There is a well known fact that a compact spacetime necessarily contains a closed timelike curve (CTC). Proof can be found in several books on GR (e.g. Hawking, Ellis, Proposition 6.4.2), and in essence goes like this:</p>
<p>The spacetime $M$ can be covered by open sets of the form $I^+(p)$, chronological future o... | g9448 | [
0.0432891771197319,
-0.012593946419656277,
0.002206344623118639,
-0.0302741639316082,
-0.06302541494369507,
0.0548713319003582,
0.05228068679571152,
-0.027502942830324173,
-0.06243780627846718,
-0.014578862115740776,
0.0554671585559845,
-0.03706614300608635,
0.014753560535609722,
0.0207718... |
<p>I am aware of the differential form language proof of the fact that for arbitrary gauge transformations the Chern-Simons' term shifts by a WZW term (on the boundary). </p>
<p>But I am getting confused if in local coordinates I try to prove that under infinitesimal gauge transformations the Chern-Simons' term is in... | g9449 | [
0.03964581713080406,
-0.05795740336179733,
-0.0050653982907533646,
-0.016488222405314445,
0.07306242734193802,
-0.002828594297170639,
0.08380714803934097,
0.06377360224723816,
-0.03191140666604042,
-0.015046542510390282,
-0.04338700324296951,
0.013050970621407032,
-0.03769713267683983,
-0.... |
<p>In their novel <a href="https://en.wikipedia.org/wiki/Prisoners_of_Power" rel="nofollow">Inhabited Island</a> by brothers Strugatsky, the inhabitants of a planet think they live on the inner surface of a giant sphere because the refraction of the atmosphere makes the surface appearing concave. </p>
<p>At the same t... | g9450 | [
-0.023667676374316216,
0.017369132488965988,
0.003530035959556699,
0.00693792337551713,
0.03274058923125267,
0.05970924720168114,
-0.025694916024804115,
0.000647166627459228,
-0.02582852728664875,
0.030724499374628067,
0.048028308898210526,
-0.014587604440748692,
0.015537960454821587,
0.00... |
<p>How does the size of humans compare to the size of other objects in the universe? Are we among the relatively large or the relatively small things?</p>
<p>My very preliminary research suggests that the smallest thing in the physical universe is the quantum foam which should be about Planck length or 10<sup>-35</su... | g9451 | [
0.029785707592964172,
0.03620854765176773,
0.02406974509358406,
-0.05470211058855057,
-0.04051532223820686,
0.04236020892858505,
-0.005381729453802109,
-0.02107819728553295,
-0.014002866111695766,
-0.040219102054834366,
0.0478261299431324,
-0.018400313332676888,
-0.035210639238357544,
0.02... |
<p>I have a super stupid question about deriving Eq. (1.2.17) in Polchinski's string theory, vol 1.</p>
<p>The book seems to derive from </p>
<p>$$\tag{1.2.16} h_{ab}=\frac{1}{2} \gamma_{ab} \gamma^{cd} h_{cd} $$</p>
<p>to </p>
<p>$$\tag{1.2.17} h_{ab} (-h)^{-1/2} = \gamma_{ab} (-\gamma)^{-1/2}.$$</p>
<p>I cannot ... | g9452 | [
-0.001310141058638692,
-0.07353870570659637,
-0.011741964146494865,
-0.07826283574104309,
0.08181285858154297,
0.0036098361015319824,
0.04142630100250244,
0.008730191737413406,
-0.05634597688913345,
-0.030423467978835106,
-0.05373018980026245,
0.02941659651696682,
0.04412391409277916,
0.03... |
<p>If an enormous asteroid, approximately the size of our moon (~2000-mile diameter), was passing close to Earth, how early might we detect something that large? Or alternatively, how close could something that large get without detection?</p>
<p>[edited to change term from meteor to asteroid]</p> | g9453 | [
-0.009507295675575733,
0.009457469917833805,
0.007718756329268217,
-0.0340055450797081,
-0.05692369118332863,
0.039837662130594254,
-0.02826344594359398,
0.003396610263735056,
-0.008350973948836327,
-0.0331953689455986,
-0.004446328617632389,
0.0639372318983078,
0.05235243961215019,
-0.051... |
<p>Apologies in advance if my question seems misinformed. I am a software developer, and neither quantum mechanics nor physics are my specialties.</p>
<p>From <a href="http://physics.about.com/od/quantumphysics/f/quantumcomp.htm" rel="nofollow">http://physics.about.com/od/quantumphysics/f/quantumcomp.htm</a>:</p>
<bl... | g9454 | [
-0.0027853979263454676,
0.08504457026720047,
-0.0037201917730271816,
-0.03352148085832596,
0.023977648466825485,
-0.013425855897367,
0.004869160708039999,
0.04398243874311447,
-0.007930132560431957,
-0.030860498547554016,
-0.02402423694729805,
-0.02439679391682148,
-0.011285010725259781,
0... |
<p>Why do people say that a <a href="http://en.wikipedia.org/wiki/Perpetual_motion" rel="nofollow">perpetual machine</a> is one that runs for eternity? Wouldn't a machine that runs taking no energy from outside but sometimes needs to be restarted, such as pendulum clock, be considered a perpetual machine? It just needs... | g9455 | [
0.05044252797961235,
0.0337795726954937,
0.015456712804734707,
-0.01898227073252201,
0.0302816703915596,
-0.03399745374917984,
0.03738991916179657,
0.0061122579500079155,
-0.05310008302330971,
-0.047087639570236206,
0.020535103976726532,
0.002458092989400029,
-0.015340794809162617,
-0.0090... |
<p>Why is it convenient to choose units kT=1? It came up in this paper: <a href="http://jfi.uchicago.edu/~leop/SciencePapers/scaling%20and%20universality%20in%20statistical%20physics.pdf" rel="nofollow">http://jfi.uchicago.edu/~leop/SciencePapers/scaling%20and%20universality%20in%20statistical%20physics.pdf</a> in page... | g9456 | [
0.022195998579263687,
0.05758724734187126,
-0.01802096888422966,
0.0029249449726194143,
0.03886418417096138,
0.005109380930662155,
0.01545496191829443,
0.033291351050138474,
-0.042898595333099365,
0.05201809108257294,
0.008831455372273922,
-0.0018081676680594683,
0.041537825018167496,
0.02... |
<p>Do low energy photons have greater entropy than high energy photons, or is the entropy of all photons the same (and the relationship between high and low entropy radiation is just a function of the number of photons - i.e. a closed system with more photons has higher entropy than the same sized system with fewer pho... | g9457 | [
-0.010153956711292267,
0.0032974055502563715,
0.020178113132715225,
-0.023209596052765846,
0.028777681291103363,
-0.028189193457365036,
-0.028502680361270905,
0.06500368565320969,
-0.03910418227314949,
-0.02600705251097679,
-0.009588194079697132,
0.02546803466975689,
-0.005057704634964466,
... |
<p>I was under the impression that glass was transparent to light with a wavelength above ultraviolet, but when playing with my latest toy, an infrared thermometer which brought up a question <a href="http://physics.stackexchange.com/questions/121299/why-does-my-infrared-thermometer-say-the-sky-is-at-2-%C2%B0c">I asked... | g9458 | [
0.0443246029317379,
-0.015515732578933239,
0.0017339001642540097,
0.018083471804857254,
0.022574152797460556,
0.05168653279542923,
0.01134474016726017,
0.06280121207237244,
0.015757204964756966,
-0.004770459141582251,
0.0232220608741045,
0.04784606769680977,
0.03744456171989441,
0.03324907... |
<p>Several papers such as <a href="http://mail.sci.ccny.cuny.edu/~jtu/TuPRL03.pdf" rel="nofollow">this (warning, PDF)</a> and <a href="http://www.wiley-vch.de/vch/journals/2231/pss40/167_177.pdf" rel="nofollow">this (PDF again)</a> talk about how, near the electronic percolation transition for a metallic 2D film, the r... | g9459 | [
0.02092088758945465,
0.010407712310552597,
0.002959767123684287,
-0.011587277054786682,
0.03664468601346016,
0.03612712398171425,
0.049802012741565704,
0.03917447477579117,
-0.028001753613352776,
0.0332065112888813,
-0.07764068990945816,
0.09606220573186874,
0.03700064867734909,
-0.0048133... |
<p>I wanted to know how can I estimate the volume of the moduli space of a Riemann surface of genus $g$ and having $n$ marked points. I am reading some old string theory papers which discuss divergences in string perturbation theory. In this respect authors such as Gross, Periwal and Shenker say that the partition func... | g9460 | [
0.022073259577155113,
0.023742441087961197,
-0.0074832625687122345,
-0.020782163366675377,
0.003076353808864951,
0.010211765766143799,
0.038184501230716705,
-0.003963364288210869,
0.0008333587320521474,
-0.004483901429921389,
-0.04423997551202774,
0.017864786088466644,
-0.0109904445707798,
... |
<p>I've only recently started learning basic electrodynamics, but I don't understand why a loop of coil with a small area and a magnet falling through will produce a larger emf than a loop of coil with a larger area with the same magnetic field falling through. </p>
<p>To clarify, lets say you have a loop of coil and ... | g9461 | [
0.050097428262233734,
-0.023008424788713455,
0.000997202005237341,
-0.03701665624976158,
0.03111352026462555,
0.09365148097276688,
0.07224208861589432,
-0.01724500209093094,
-0.06446819752454758,
-0.0730690211057663,
-0.04454975947737694,
0.008343073539435863,
0.05193106830120087,
0.058171... |
<p>For a flow over a smooth sphere, does the wake region increases with increase in <a href="http://en.wikipedia.org/wiki/Reynolds_number" rel="nofollow">Reynolds number</a>? And if so, then why? </p> | g9462 | [
0.010089597664773464,
0.038655564188957214,
0.0015613731229677796,
-0.025057831779122353,
0.017360486090183258,
-0.004073955584317446,
0.0534345917403698,
-0.00503182876855135,
0.0021929184440523386,
-0.05184663459658623,
0.004761370364576578,
0.021469950675964355,
0.07225354760885239,
0.0... |
<p>Wave theory does not account for the photon model, which was developed only to explain quantum effects like photoelectric effect.
Then why do we talk about a photon's reflection and rarefaction, as that would require it to have wave properties? This has been mentioned here: (<a href="http://en.m.wikipedia.org/wiki/... | g309 | [
0.014384789392352104,
0.05368011072278023,
0.011195594444870949,
0.025583749637007713,
0.06117945909500122,
0.049744606018066406,
0.05282150208950043,
0.072110615670681,
0.035093773156404495,
-0.047795988619327545,
0.029970739036798477,
-0.009234534576535225,
0.0170943271368742,
0.03259788... |
<p>For a potential $V$, how do we define the mass of a small fluctuation around its vacuum? For example I have the potential</p>
<p>$$ V_\mathrm{eff}(\phi) = \frac{1}{2} \left(\frac{\rho}{M^2} - \mu^2\right) \phi^2 + \frac{1}{4} \lambda \phi^4. $$</p>
<p>What is the definition of the mass of small fluctuations around... | g9463 | [
0.040764592587947845,
-0.008587012067437172,
-0.014680355787277222,
-0.009637896902859211,
0.055719416588544846,
0.08818656206130981,
0.029171274974942207,
0.0016567904967814684,
-0.04181394353508949,
-0.020799240097403526,
-0.012555986642837524,
0.03937648981809616,
0.023372063413262367,
... |
<p>Say there is a horizontal rod, where a force $P$ is applied to the right hand side of the rod to drag it horizontally to the right. If I drew a force diagram, I'd put some vector with a length of $\| \mathbf{P} \|$ coming out of the right end of the rod. In actuality, if the rod is composed of ten particles, then is... | g9464 | [
0.04416631907224655,
0.04813845828175545,
-0.01928534545004368,
-0.06751418858766556,
0.035532739013433456,
0.028147511184215546,
0.03945261240005493,
-0.00007689173799008131,
-0.10032045841217041,
-0.0524490624666214,
0.029771864414215088,
-0.027233466506004333,
0.030323954299092293,
-0.0... |
<p>I want to find out how many calories are burned on any particular hike by any particular by using a formula. I figure it's probably a simple physics question, but since I never took physics, I don't know the math to do it. </p>
<p>My premise is that you will expend (A) energy (calories) when moving (B) weight (C) d... | g9465 | [
0.00116507348138839,
0.015166383236646652,
0.010900159366428852,
0.030921682715415955,
-0.023614056408405304,
-0.030852127820253372,
0.04104653745889664,
0.05164723843336105,
-0.05413949117064476,
-0.03545188531279564,
0.0046380129642784595,
0.03644808754324913,
0.05151939019560814,
0.0451... |
<p>Is it possible to use a set of cylindrical mirrors and software correction to build an optical reflector telescope, instead of using a paraboloid reflector? By 'cylindrical' I actually mean a planar mirror curved to a parabolic profile.</p>
<p>In other words, rather than focusing light in 360 degrees in one step, i... | g9466 | [
0.011367110535502434,
-0.04568793997168541,
-0.0009320817771367729,
-0.009207267314195633,
0.02702741138637066,
-0.01005424652248621,
-0.0019480576738715172,
0.00282827066257596,
-0.047470420598983765,
0.005196879152208567,
0.014946307986974716,
0.042362798005342484,
0.05773071572184563,
-... |
<p>In my understanding, there exists a critical mass for which a star needs to be in order for it to collapse into a black hole. This also applies to a certain critical density of gas in order for stars to form in the first place. However, given a massive star or a massive amount of gas, it must have a relatively large... | g9467 | [
0.009346121922135353,
-0.01706909015774727,
0.010896953754127026,
-0.014253251254558563,
0.025917164981365204,
0.022335205227136612,
-0.002795321401208639,
0.036112021654844284,
-0.04309205710887909,
-0.057226214557886124,
0.019760306924581528,
0.007990489713847637,
0.07051524519920349,
-0... |
<p>We owe a debt to Bell labs with Shockley, Bardeen and Brattain for inventing the semiconductor.
All have now passed on. I remember seeing my first transistor radio in the early 60's.
Shockley developed the very important diode equation.
I was reading through one of my good old engineering books where the dynamic r... | g9468 | [
0.018416523933410645,
0.027720460668206215,
-0.016262616962194443,
-0.022918038070201874,
0.017832458019256592,
-0.04638233780860901,
0.07956931740045547,
-0.031812604516744614,
-0.05310719460248947,
0.05338625982403755,
-0.0018909722566604614,
0.0867990106344223,
0.045827921479940414,
0.0... |
<p>Potential flow around a circular cylinder is a classic solution. But I am wondering if there is any solution similar to this for the flow past a square cylinder?</p> | g9469 | [
0.03841312229633331,
-0.019422847777605057,
0.011930021457374096,
-0.01182306557893753,
0.01148068718612194,
-0.01586325094103813,
-0.005383035633713007,
-0.040530283004045486,
-0.029946137219667435,
0.03179940581321716,
0.05209246277809143,
0.007286193314939737,
0.0633063018321991,
-0.004... |
<p>and another exam question, this is about current research:</p>
<blockquote>
<p>Interference of matter waves has been studied using ultra-cold atoms. The phase of a matter wave for free-falling cold-atoms at time $t$ and height $y$ is given as
$$\phi(y,t) = \phi(y_0,t) + Et - \int_{y_0}^y dy' k(y')$$
... | g9470 | [
0.006513781845569611,
0.005569888278841972,
0.015510134398937225,
-0.007192977704107761,
0.019293542951345444,
0.041964706033468246,
0.035008203238248825,
0.022390782833099365,
-0.04130462929606438,
-0.031589753925800323,
-0.028981879353523254,
0.026824867352843285,
-0.02993469312787056,
-... |
<p>I am reading <em>A Brief History of Time</em> by Stephen Hawking, and in it he mentions that without compensating for relativity, GPS devices would be out by miles. Why is this? (I am not sure which relativity he means as I am several chapters ahead now and the question just came to me.)</p> | g9471 | [
0.03916352242231369,
0.06757548451423645,
-0.0008858628571033478,
0.06720100343227386,
0.0037335713859647512,
0.02434363402426243,
0.03502229228615761,
0.0399012565612793,
-0.014112863689661026,
0.005253318231552839,
0.017541706562042236,
-0.012799299322068691,
0.018504979088902473,
0.0494... |
<p>A superconducting wire has no electrical resistance and as such it does not heat up when current passes through it. Non-superconducting wires can be damaged by too much current, because they get too hot and melt. But since current is the flow of electrons, surely unlimited electrons can't flow?</p> | g9472 | [
0.023264361545443535,
0.033564649522304535,
0.013297856785356998,
-0.02627318724989891,
0.0008623206522315741,
0.03674826771020889,
0.004534682258963585,
0.047951340675354004,
-0.001932312035933137,
-0.026248086243867874,
-0.034109413623809814,
0.047873903065919876,
-0.0735233947634697,
-0... |
<p>I have two parallel non conducting charged planes with opposite charges $6\mu C/m^2$, area $A = 3m^2$ and distance between the planes $d = 0.004 m$. I know the potential between these two planes is $$V = \frac{\sigma\times d}{\epsilon_0}$$
But if I put a conducting sheet of thickness $h = 0.001 m$ with the same area... | g9473 | [
0.06533420830965042,
-0.004612003453075886,
-0.0018171978881582618,
-0.03941940516233444,
0.0779329314827919,
0.05722258612513542,
-0.03388955444097519,
-0.01163657195866108,
-0.09634924679994583,
0.05518154054880142,
0.013890431262552738,
0.01296838279813528,
-0.06904604285955429,
0.01640... |
<p>The geometry of my semiconductor device is given below. The blue regions are gold, the grey ones - gallium arsenide (n-doped to $2.9 \times 10^{15} \mathrm{cm^{-3}}$). The dimensions are μm, i.e. it is 500μm wide, the bottom GaAs is 400μm thick, then a layer of gold follows, then a 15μm layer of GaAs, and a 5μm laye... | g9474 | [
0.04238617420196533,
-0.008397270925343037,
-0.007239941973239183,
-0.017110498622059822,
0.029889589175581932,
0.06304052472114563,
0.09010577946901321,
0.030964070931077003,
0.0341186486184597,
-0.006715795025229454,
-0.024800894781947136,
0.067044697701931,
0.02928335592150688,
-0.00152... |
<p>$$\mathbf D = \varepsilon \mathbf E$$
I don't understand the difference between $\mathbf D$ and $\mathbf E$.
When I have a plate capacitor different medium inside will change $\mathbf D$, right?
$\mathbf E$ is only dependent from the charges right?</p> | g9475 | [
0.07475562393665314,
0.027173111215233803,
-0.01973261497914791,
-0.02167678065598011,
0.0722750648856163,
0.038695476949214935,
0.056326743215322495,
-0.04448772966861725,
-0.02514292672276497,
-0.04584454745054245,
-0.08029739558696747,
0.08334898948669434,
0.026590440422296524,
0.000010... |
<p>I don't really know much about Quantum mechanics, but would like to know one simple fact.</p>
<p>The state function $\Psi(r, t)|$ whose magnitude gives the probability density of the position of the particle and the magnitude of its ($\Psi(r, t)$) fourier transform gives probability density of its momentum. Is ther... | g9476 | [
0.05055880919098854,
-0.0036871228367090225,
-0.01618698053061962,
-0.07657752931118011,
0.04771443083882332,
0.008886354975402355,
-0.003564375452697277,
0.06329155713319778,
-0.04465765506029129,
-0.006959126330912113,
-0.007337520364671946,
-0.0379321351647377,
0.0023570372723042965,
-0... |
<p>Are there any objects out there that have since vanished, but because of their distance and the travel time for light, can be seen <em>with the naked eye</em>? Or are those things only visible with magnification? How much magnification at least?</p> | g9477 | [
0.016788681969046593,
0.03223232179880142,
-0.0043303449638187885,
0.015171924605965614,
-0.025143669918179512,
0.03460521996021271,
-0.08190527558326721,
-0.005690230056643486,
0.037672173231840134,
0.047041866928339005,
0.016605913639068604,
-0.0015462792944163084,
0.08689352124929428,
-... |
<p>While an object is moving, relativity will say it weighs more, especially so as it approaches light speed. </p>
<p>The increase in energy is then easily sensed as an increase in mass
(Almost as a rock in your hand feels 'lighter' than the rock that falls upon your hand, before the energy of velocity is transferred ... | g9478 | [
0.0511782243847847,
0.019759155809879303,
0.024551555514335632,
-0.02384672313928604,
0.07269851863384247,
0.0033539466094225645,
0.04029054194688797,
0.036757051944732666,
-0.03928789868950844,
0.008376011624932289,
0.018471824005246162,
-0.07216086983680725,
-0.0015356963267549872,
0.027... |
<p>I am in need of a book (preferably) or other reference material which would help technicians determine whether porosity exists in the fracture face of a tensile test bar for a variety of different types of metal. The reference would not necessarily need to show fracture faces, just porosity in general. Types of me... | g9479 | [
0.07577940821647644,
0.06562959402799606,
-0.014062519185245037,
-0.03341403976082802,
0.06583088636398315,
-0.0048570032231509686,
0.06039547547698021,
0.0038370501715689898,
-0.0444476418197155,
0.02556002326309681,
0.05068642273545265,
-0.011089729145169258,
-0.016667407006025314,
-0.01... |
<p>I'm looking for some good explanation on leading logarithmic approximation (LLA) in QCD; in particular, what types of contributions can be neglected while assuming LLA?</p> | g9480 | [
0.05001983791589737,
-0.012878987938165665,
-0.022220470011234283,
-0.034940075129270554,
0.02516297437250614,
-0.005529351532459259,
0.02554226666688919,
-0.004860509652644396,
0.01085010077804327,
-0.058576036244630814,
0.01756582409143448,
0.029447294771671295,
0.014413832686841488,
0.0... |
<p>I have been thinking about this question for quiet a long time but, couldn't make up an answer myself. Usually when someone asks about why a system is the way it is we answer it by saying that it is the most stable lowest energy state(to know about why a system should be at its lowest energy state for its stability ... | g9481 | [
0.027147984132170677,
0.04386176913976669,
0.013194242492318153,
0.0029437867924571037,
0.062417466193437576,
0.018650954589247704,
-0.043671026825904846,
-0.010485254228115082,
-0.03402112051844597,
-0.06353460997343063,
0.029135093092918396,
-0.011389791034162045,
-0.04787837713956833,
-... |
<p>If a particle is being expelled from the Black Hole and an antiparticle is being driven into it, shouldn't the opposite occur as well and in the same frequencies?</p>
<p>I mean Black holes should emit antiparticle radiation as well and gather energy from it and the black hole energy shouldn't change, right?</p>
<p... | g9482 | [
0.022013550624251366,
0.0070342556573450565,
0.028220076113939285,
-0.010931946337223053,
0.058173783123493195,
0.024178920313715935,
-0.015976395457983017,
0.05062931403517723,
-0.06226174905896187,
0.01852136105298996,
0.05910765007138252,
0.08746889233589172,
0.004131297115236521,
-0.00... |
<p>From my bookish knowledge all planet revolve around the sun in anticlockwise direction and electron also moves in the anti clock around the nucleus. Is there any specific reason behind the stability of anticlock wise direction? </p> | g9483 | [
0.02335907332599163,
0.038371991366147995,
0.004709386732429266,
0.019873348996043205,
0.09362391382455826,
0.053874652832746506,
0.025503583252429962,
-0.048841722309589386,
-0.005969415884464979,
-0.06231614202260971,
0.033834539353847504,
0.07807660847902298,
0.03261445462703705,
0.0311... |
<p>In this problem there is a cylinder that is closed at both ends and has thermally insulated walls. It is divided into 2 parts by a movable, frictionless, thermally insulated piston. There is a heating coil in the left side of the cylinder and there are $N$ molecules of an ideal gas in each compartment. The origin... | g9484 | [
-0.004001710098236799,
-0.034467365592718124,
0.004443511366844177,
0.004130405839532614,
-0.007669914048165083,
-0.0642920508980751,
0.03458435460925102,
0.025441084057092667,
-0.08918438106775284,
0.022055529057979584,
-0.07888481020927429,
0.015115048736333847,
-0.002881442429497838,
-0... |
<p>I have been playing around with Tesla coils for a while now, but one limiting factor for portability is the fact that it requires an earth connection on the secondary coil.</p>
<p>Since a Tesla coil works with resonant inductive coupling, I was wondering if it would be theoretically possible to wirelessly couple th... | g9485 | [
0.017911337316036224,
-0.012440728023648262,
0.007645907811820507,
-0.03353201597929001,
-0.00514196278527379,
0.0019138744100928307,
-0.08030936866998672,
-0.002147255465388298,
0.0415625236928463,
-0.013913770206272602,
-0.01480659656226635,
-0.01520333718508482,
-0.015597044490277767,
0... |
<p>I don't want this to be a "do my home work question" so please tell me how I can make this question helpful for other people.</p>
<p>In my physics assignment I found the question below. I'd think that both FBD's and $F_{net}$s are the same for each scenario; since the track is friction-less the rider doesn't need t... | g9486 | [
0.052826300263404846,
0.023806143552064896,
0.003003366757184267,
0.015339230187237263,
0.07891499996185303,
-0.03936384990811348,
0.07253651320934296,
-0.04287150502204895,
-0.07546576857566833,
-0.07155854254961014,
0.01897123083472252,
-0.03259001672267914,
-0.00184312101919204,
0.00988... |
<p>I understand from my very limited knowledge of relativity that an object traveling at relativistic speeds essentially experiences the progression of time slow to a crawl. Since, according to <a href="http://en.wikipedia.org/wiki/General_relativity" rel="nofollow">Einstein's GR theory</a>, gravity bends spacetime, do... | g310 | [
0.009520855732262135,
0.06370722502470016,
-0.0040379236452281475,
0.007450609002262354,
0.033411066979169846,
0.06056937202811241,
0.08033132553100586,
0.059020280838012695,
-0.06010881066322327,
-0.01806214451789856,
0.020084919407963753,
-0.042888663709163666,
0.04341772571206093,
0.012... |
<p>I was wondering when I boil water in a pot it only shakes too much while boiling. But I could not figure out why tea rises in the pot when we boil it. it is also a liquid but it starts rising up till it jumps out of the pot and tries to kill the flame. </p>
<p>I think this happens due to change in the adhesive prop... | g9487 | [
-0.0034517343156039715,
0.03754555806517601,
-0.00218641827814281,
0.031158113852143288,
0.0073888567276299,
0.028504204005002975,
0.0027139519806951284,
0.018942521885037422,
-0.003644907847046852,
-0.031961578875780106,
0.033361244946718216,
0.021034210920333862,
0.027167409658432007,
0.... |
<p>"Now we turn our attention to what happens in $S'$, in which the particle is at rest and the wire is running past (toward the left in the figure) with the speed $v$. The positive charges moving with the wire will make some magnetic field $\ B'$ at the particle. But the particle is now at $rest$, so there is no magne... | g9488 | [
0.053973861038684845,
-0.016726253554224968,
0.0021586259827017784,
-0.012509583495557308,
0.0800924226641655,
0.047174833714962006,
0.038949258625507355,
0.02614348754286766,
-0.06441274285316467,
0.008057721890509129,
-0.007752327714115381,
0.02359192818403244,
-0.10037580132484436,
-0.0... |
<p>Quantum shot noise (either optical intensity noise or electrical current noise) described by the noise spectral density of $2 e I$ (electrically) or $2 h \nu P$ (optically).</p>
<p>So it is white noise. I know this basically comes from the derivation, where we model electron or photon events as infinitely short (wi... | g9489 | [
0.006055223755538464,
-0.026835933327674866,
0.003426559502258897,
-0.006074993871152401,
0.06301005184650421,
0.03346749022603035,
-0.014706495217978954,
0.06112663820385933,
-0.006060641258955002,
0.04240189865231514,
0.008345804177224636,
0.060824938118457794,
0.02675958350300789,
0.012... |
<p>My old theoretical physics professor used to say that (already) (special?) relativity shows that "the future is not predictable". Any ideas how this should be interpreted?</p> | g9490 | [
0.012294145300984383,
0.04191461205482483,
0.005708770360797644,
0.009086687117815018,
-0.036945145577192307,
0.025157973170280457,
0.010480488650500774,
0.038367319852113724,
0.0010318029671907425,
-0.06964889913797379,
0.03466561809182167,
0.002408229745924473,
0.05618581548333168,
-0.00... |
<p>A wet object or a volume of water will decrease in temperature due to the effect of evaporation. We understand this to be because of the molecular kinetics, where the faster water molecules escape and become a part of the air. Since those that escape have more energy than the average, the process decreases the tem... | g9491 | [
0.053813427686691284,
0.004898645915091038,
0.012776758521795273,
0.04748417064547539,
-0.03161638602614403,
0.04194656386971474,
0.0063300044275820255,
0.06613416969776154,
-0.061423104256391525,
-0.03720271959900856,
-0.019657324999570847,
-0.007755533792078495,
0.018808776512742043,
0.0... |
<p>A solid can exist in two phases, with energies</p>
<p>$$U_{1}(S,V)=\frac{S^2}{a_1}+b_{1}V(V-2V_{0})$$</p>
<p>$$U_{2}(S,V)=\frac{S^2}{a_2}+b_{2}V(V-2V_{0})$$</p>
<p>where $a_{1},a_{2},b_{1},b_{2},V_{0}$ are positive constants, with $a_{1}>a_{2}$ and $b_{1}<b_2$.</p>
<p>Consider a phase transition between th... | g9492 | [
0.03551723062992096,
-0.012437486089766026,
0.008205102756619453,
0.021041827276349068,
0.03834960237145424,
-0.017187131568789482,
-0.045079734176397324,
0.05524930730462074,
-0.030323904007673264,
0.052405502647161484,
-0.06048516184091568,
0.024858569726347923,
-0.030767520889639854,
-0... |
<p>Why can't the work done by a <a href="http://en.wikipedia.org/wiki/Conservative_force" rel="nofollow">non-conservative force</a> be zero? The displacement along a closed path is always zero. So, whatever be the type of force, variable or constant, the work has to be zero. Why do we need to calculate the work done fo... | g9493 | [
0.016290554776787758,
0.017203813418745995,
0.004381340462714434,
0.01359535101801157,
0.03968319296836853,
0.0015378521056845784,
0.06673883646726608,
0.06506647914648056,
-0.07103943079710007,
-0.07097785174846649,
0.036875151097774506,
-0.028854480013251305,
-0.03303299844264984,
-0.032... |
<blockquote>
<p><em>The curvature of Mars is such that its surface drops a vertical
distance of 2.0 meters for every 3600 meters tangent to the surface.
In addition, the gravitational acceleration near its surface is 0.4
times that near the surface of the Earth. What is the speed a golf
ball would need to orb... | g9494 | [
0.037504326552152634,
0.05939081683754921,
0.006674539297819138,
0.020253345370292664,
0.04211945831775665,
0.060912493616342545,
0.03548331558704376,
-0.018031571060419083,
-0.07771621644496918,
-0.000571727636270225,
0.01191028393805027,
0.0743330791592598,
0.04844658449292183,
-0.000375... |
<p>I'm reading the following <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.2153-3490.1967.tb01462.x/pdf" rel="nofollow">paper</a> and do not entirely understand a point that the author is trying to make. In page 99 (2 of article) the author refers to the following equation:</p>
<p>$$ Q^{*} = \beta S^{*}e^{-\be... | g9495 | [
0.037616513669490814,
0.002736729569733143,
-0.007022194564342499,
0.01848357357084751,
0.06972102075815201,
0.0358123704791069,
0.07168988883495331,
-0.009162562899291515,
-0.0009000065620057285,
-0.0346265509724617,
-0.02655111625790596,
0.08101681619882584,
0.022992433980107307,
0.03653... |
<p>What exactly is the relationship between the continuity equation and the wave equation?</p>
<p>Suppose $J^\mu$ is a contravariant vector that satisfies the <a href="http://en.wikipedia.org/wiki/Continuity_equation#Special_relativity" rel="nofollow">continuity equation</a> $\partial_\mu J^\mu=0$. Let $J^\mu$ be defi... | g9496 | [
0.056005775928497314,
-0.024871764704585075,
-0.02377559058368206,
0.004878256004303694,
0.0008051536278799176,
0.04213394969701767,
0.07654497772455215,
0.0436757355928421,
0.021634060889482498,
-0.01626177877187729,
-0.04163798689842224,
0.0033532739616930485,
0.011839782819151878,
0.030... |
<p>Suppose you have a set of charges that are Newtonian (not quantum and not fast-moving) point particles. They are subject to known (but not necessarily constant) external forces ($F_{ext}$), as well as mutual electrostatic forces ($F_s$).</p>
<p>We want to estimate the <em>electromagnetic</em> forces ($F_m$) on each... | g9497 | [
0.0053974324837327,
-0.03973766043782234,
-0.012354624457657337,
-0.03576114401221275,
0.035454265773296356,
-0.006815853528678417,
-0.0038661386352032423,
-0.004823816940188408,
-0.06704428791999817,
0.0687379240989685,
-0.0031368413474410772,
0.015925299376249313,
-0.008478227071464062,
... |
<p>For example, let's consider a quadratic fermionic Hamiltonian on a 2D lattice with translation symmetry, and assume that the Fourier transformed Hamiltonian is described by a $2\times2$ Hermitian matrix $H(\mathbf{k})=a(\mathbf{k})\sigma_x+b(\mathbf{k})\sigma_y+c(\mathbf{k})\sigma_z $ and has a finite energy gap, th... | g9498 | [
0.03616899624466896,
0.006560675799846649,
-0.025488656014204025,
-0.02035626769065857,
0.06384998559951782,
-0.048052266240119934,
0.03364809975028038,
0.061968423426151276,
-0.0061533162370324135,
0.004402117803692818,
-0.004935278091579676,
0.06238604709506035,
-0.030487755313515663,
-0... |
<p>I am writing a novel, and although I have a background in physics, I am unsure of the exact equations to use.</p>
<p>Specifically:</p>
<p><strong>For a photon-sail ship, how powerful would a driving laser need to be in order for the ship to reach an acceleration of ~0.5g?</strong></p>
<p>Assuming we are only talk... | g9499 | [
-0.019863160327076912,
0.11276708543300629,
0.0019301804713904858,
0.019683772698044777,
-0.013542266562581062,
0.0039228834211826324,
-0.026532700285315514,
0.013972651213407516,
-0.04339706152677536,
-0.01582293212413788,
0.043278470635414124,
0.05350298807024956,
0.04744075983762741,
-0... |
<p>The following is defined, where $\epsilon \to 0^+$ is a cutoff:
$$ \mathcal{F}(Z)=\int_{\epsilon}^\infty \frac{\mathrm{d}s}{s}
\frac{1}{\sinh^2 s/2} e^{-sx}. $$</p>
<p>Question: how do we see that $\mathcal{F}$ has a
perturbative + non-perturbative expansion (in $x \gg 0$) given by</p>
<p>$$ \mathcal{F}(Z) = \sum_... | g9500 | [
-0.01081088650971651,
0.00977302622050047,
-0.007075814064592123,
-0.0627518892288208,
0.022156553342938423,
-0.016350682824850082,
0.04034433141350746,
0.00220182235352695,
0.011624027974903584,
0.021067481487989426,
-0.02193494141101837,
0.04232056438922882,
0.03340351581573486,
0.041240... |
<p>Does a phase transition occur as a gas is heated to create a plasma? If so, is this a first or second order phase transition?</p>
<p>Also, does the presence of a phase transition depend on the pressure or composition? It seems to me that in the dilute limit (i.e. low pressures), no phase transition should occur bec... | g9501 | [
0.03105328604578972,
0.026628827676177025,
0.0115235336124897,
0.02021167427301407,
0.04944820702075958,
0.0016077677719295025,
-0.07126499712467194,
0.025831032544374466,
-0.05138741433620453,
0.02019723504781723,
-0.018941471353173256,
0.017276404425501823,
-0.015533329918980598,
-0.0338... |
<p><strong>Context</strong></p>
<p>I have been going through <a href="http://arxiv.org/abs/1302.5843" rel="nofollow">Ising formulations of many NP problems</a> by Andrew Lucas. In section 9 on page 22, the author gave an Ising formulation of the graph isomorphism problem. Here I mention it briefly.</p>
<p>Given two g... | g9502 | [
0.0368080660700798,
0.05848672240972519,
-0.018846970051527023,
-0.023220278322696686,
0.004833912011235952,
-0.04531240090727806,
0.005882733967155218,
-0.0675966814160347,
0.02862265519797802,
0.028854286298155785,
-0.015903087332844734,
0.04762950539588928,
-0.03503181412816048,
-0.0155... |
<p>I want to know if a household AC current flowing through a simple copper wire will radiate EM waves? If yes, up to what range and can they be called radio waves? </p> | g9503 | [
-0.0021445800084620714,
0.016210317611694336,
-0.011172184720635414,
0.033464815467596054,
0.030895443633198738,
0.032585904002189636,
-0.03165813162922859,
-0.045952945947647095,
-0.02100926823914051,
-0.03214138373732567,
0.004995725583285093,
0.06406097114086151,
-0.012983813881874084,
... |
<p>I am studing the Grover operator. Let be $x_0$ the marked element. Let be $t_f = \pi/2\omega$. The measurement of the register in the computational basis return $x_0$ with probability </p>
<p>$$p_{x_0}(t_f)=\langle x_0|U^{t_f}|D\rangle|=1-1/N$$</p>
<p>Where $|D\rangle$ is a diagonal state state, $U$ the grover ope... | g9504 | [
0.001751432428136468,
0.08514579385519028,
0.0055299480445683,
-0.05771290510892868,
0.03369229659438133,
0.007066833786666393,
0.08409642428159714,
0.0601341649889946,
0.04109453409910202,
-0.038080211728811264,
-0.009187448769807816,
0.03632670268416405,
-0.014615846797823906,
0.02631427... |
<p>I have always wondered and once I even got it, but then completely forgot. I understand that gravity causes high and low tides in oceans, but why does it occur on the other side of Earth?</p> | g9505 | [
0.10818582028150558,
0.020267309620976448,
-0.006821294315159321,
-0.0009243123349733651,
0.06701982021331787,
0.14697383344173431,
0.04724844917654991,
0.011478924192488194,
-0.014865590259432793,
-0.07905338704586029,
-0.01874682866036892,
0.01935737207531929,
0.0725698471069336,
0.04419... |
<p>I am solving this problem from a previous year question paper</p>
<blockquote>
<p>A series RLC circuit has resistance of 1k at resonant frequency and half power frequencies are
20kHz and 100kHz. Determine (i) The bandwidth (ii) The value of L and C iii) Show the nature of
variation of impedance and power fact... | g9506 | [
-0.005850956775248051,
0.012061648070812225,
0.004055538214743137,
-0.05665171891450882,
0.024036481976509094,
-0.04562029987573624,
0.04547278955578804,
0.010095378383994102,
-0.03008245676755905,
0.02193070948123932,
-0.06972324103116989,
0.06410737335681915,
-0.018467895686626434,
0.044... |
<p>When the spin of a quantum entangled particle is measured, is it only possible to do an instantaneous measurement, or can a particles spin be held in a collapsed state by constantly observing it?</p>
<p>In other-words, can you inspect particle A's spin and continuously observe it while sampling B's spin multiple ti... | g9507 | [
-0.031715743243694305,
-0.02036302536725998,
0.00865135621279478,
-0.03754676505923271,
0.028874758630990982,
-0.015210326761007309,
0.015580789186060429,
0.02613905258476734,
0.003924753982573748,
0.02646329067647457,
0.0009811029303818941,
0.010330826044082642,
-0.0401153527200222,
-0.02... |
<p>I'm trying to compute the expectation value of energy for a certain state in an <a href="http://en.wikipedia.org/wiki/Particle_in_a_box" rel="nofollow">infinite potential well</a> but I'm getting contradictory answers.</p>
<p>The well has potential
\begin{align}
V(x) = \left\{
\begin{array}{lr}
0 &a... | g9508 | [
0.010928109288215637,
0.022428911179304123,
-0.007128790952265263,
-0.09589527547359467,
0.010681599378585815,
-0.02211654558777809,
-0.016359081491827965,
0.07292749732732773,
-0.0368201844394207,
-0.001266694744117558,
0.000669446773827076,
-0.017596345394849777,
-0.018144698813557625,
0... |
<p>I found the following picture in the Internet and I am curious how from a physicist point of view to explain it.</p>
<p><img src="http://i.stack.imgur.com/r33vQ.jpg" alt="enter image description here"></p>
<p>Basically the idea is the following. If you are a normal person - you suppose to see Einstein here, but if... | g9509 | [
-0.002762397052720189,
0.07317585498094559,
-0.005800073966383934,
-0.004979063291102648,
-0.003390972502529621,
0.050258927047252655,
0.03203147277235985,
0.030367324128746986,
-0.007651729509234428,
0.03548983111977577,
0.045385632663965225,
0.015254156664013863,
0.05376684293150902,
-0.... |
<p>$$H_{tot}=\sum \dfrac{p_i^2}{2m}+\sum\dfrac{p_I^2}{2M_I}+\sum V_{nucl}(r_i)+\dfrac{1}{2}\sum_{i\ne j} \dfrac{e^2}{|r_i-r_j|}+\dfrac{1}{2}\sum_{I\ne J}\dfrac{z_Iz_Je^2}{|R_I-R_J|} $$</p>
<p>with:
$$V_{nuc}(r)=-\sum_I\dfrac{z_Ie^2}{|r-R_I|}$$</p>
<p>this equation is for the total non relativistic Hamiltonian of a... | g9510 | [
0.00846592616289854,
-0.007148612756282091,
0.0005710033001378179,
0.013864757493138313,
0.05721895769238472,
-0.013155536726117134,
0.02089732512831688,
0.004383252467960119,
-0.028719207271933556,
0.0559520497918129,
0.02191791869699955,
0.026188766583800316,
-0.008429382927715778,
0.004... |
<p>According to Biot-Savart Law, if there is a charged particle in motion, there will be a magnetic field. My question is whether the counterpart of this law also holds true, i.e. if there is a magnetic field, whether there will be a charged particle be in motion.
Let me explain my question a bit more clearly. First ... | g9511 | [
0.07400748133659363,
0.05475647374987602,
0.0068811229430139065,
-0.0018262105295434594,
0.08931718021631241,
0.006737600080668926,
-0.013110395520925522,
0.05079859495162964,
-0.04686863347887993,
0.03278404101729393,
-0.018731044605374336,
-0.007710079196840525,
-0.036004237830638885,
-0... |
<p>What is the difference between the <a href="http://www.google.com/#q=vernier+constant" rel="nofollow">Vernier constant</a> and <a href="http://www.google.com/#q=least+count+of+a+vernier+caliper" rel="nofollow">least count of a Vernier caliper</a>?</p> | g9512 | [
0.09754053503274918,
0.010518079623579979,
-0.02759467624127865,
-0.0016433211276307702,
0.04592183604836464,
0.0036434647627174854,
0.07698148488998413,
0.013189208693802357,
-0.024958176538348198,
-0.02156955376267433,
-0.05356563627719879,
0.0006522669573314488,
0.001166495494544506,
0.... |
<p>For example, I am working on this problem, and I don't know where to begin. All the relationships that I can think of include a constant amplitude. [A (w/w^2) sin/cos theta]</p>
<p>Here's the problem:
A person rides on a mechanical bucking horse that oscillates up and down with simple harmonic motion. The period of... | g9513 | [
0.04942622035741806,
0.020132532343268394,
0.003963186405599117,
-0.03233296051621437,
-0.008324205875396729,
-0.03324628248810768,
0.018604964017868042,
-0.013748963363468647,
-0.0011988080805167556,
-0.009921933524310589,
-0.013772329315543175,
-0.007791595999151468,
0.0036854210775345564,... |
<p>I am trying to understand the differences between <a href="http://en.wikipedia.org/wiki/Wavefunction" rel="nofollow">wavefunction</a>, <a href="http://en.wikipedia.org/wiki/Probability" rel="nofollow">probability</a> and <a href="http://en.wikipedia.org/wiki/Probability_density" rel="nofollow">probability density</a... | g9514 | [
0.008408432826399803,
-0.019503137096762657,
-0.006692042574286461,
-0.03278231993317604,
0.060587383806705475,
-0.013133236207067966,
0.058240652084350586,
0.018466809764504433,
-0.034803684800863266,
-0.02481725439429283,
-0.02629842422902584,
-0.027740895748138428,
0.041340842843055725,
... |
<p>In quantum mechanics, any density matrix (or density operator) is Hermitian. Observables are also represented by Hermitian operators. So it follows that a density matrix can also be interpreted as an observable.</p>
<p>What is the physical meaning of this observable?</p> | g9515 | [
0.027909239754080772,
0.002747870748862624,
0.016581587493419647,
-0.03814201429486275,
0.0717216357588768,
0.06018008664250374,
-0.02278107777237892,
0.020931074395775795,
-0.04955829307436943,
0.0005741171771660447,
0.013066468760371208,
-0.018594898283481598,
0.03167373687028885,
-0.041... |
<p>I was working over some problems from my physics textbook, and I came across this one, it involves circular movement:</p>
<p>A car with the mass of 1t is moving over a hill with the velocity of 20 m/s. The radius of the hill (which can be viewed as a half-circle) is 100m.</p>
<p>When it comes to the top of the hil... | g9516 | [
0.0022918309550732374,
0.006613180972635746,
0.0005907380837015808,
0.013317613862454891,
0.06174453720450401,
-0.036662012338638306,
0.07420095801353455,
-0.007908896543085575,
-0.029462233185768127,
-0.024184104055166245,
-0.05042058229446411,
-0.0013261813437566161,
-0.0018323279218748212... |
<p>Is there light tunneling taking place in optically transparent mediums like glass? wherein light travels a larger path in these mediums without interacting with atoms and without any change in velocity, frequency, wavelength or momentum? but just getting affected by the field of atom and following the least resistan... | g9517 | [
0.016788635402917862,
0.05104367807507515,
0.018833918496966362,
0.04605535790324211,
-0.011924665421247482,
0.020339805632829666,
0.01081384439021349,
-0.0033593052066862583,
0.05192074924707413,
-0.01361147966235876,
0.018944351002573967,
-0.02445610985159874,
0.03172961622476578,
-0.024... |
<p>I thought of a thought experiment that had me questioning how <a href="http://en.wikipedia.org/wiki/T-symmetry" rel="nofollow">time reversal</a> works in <a href="http://en.wikipedia.org/wiki/T-symmetry#Time_reversal_in_quantum_mechanics" rel="nofollow">quantum mechanics</a> and the implications. The idea is this ..... | g9518 | [
-0.026198748499155045,
0.013447060249745846,
0.021760372444987297,
-0.03896008059382439,
0.03502245247364044,
0.011115695349872112,
0.0024076218251138926,
0.04601723328232765,
-0.056268926709890366,
-0.015612422488629818,
0.03159406781196594,
0.011608223430812359,
0.044395364820957184,
0.0... |
<p>Aside from Noether's Theorem, how do we know energy is conserved?</p>
<p>Energy is the capacity of a system to do work. It's the number that tells me how much "force" a system can apply over a distance. For long I knew we could create forces. However, the only reason... The physical reason that conservation of ener... | g9519 | [
0.04652506858110428,
0.017276864498853683,
-0.005929742474108934,
0.004440936725586653,
-0.010019460693001747,
0.027181629091501236,
0.031146813184022903,
0.023723427206277847,
-0.07141188532114029,
-0.03326085954904556,
0.014662130735814571,
-0.030820421874523163,
-0.019187482073903084,
-... |
<p>I am going through the idea of stabilizer formalism.</p>
<p>Defined what is a Pauli group $P_n$ and its properties, we describe a stabilizer set $S$ as:
$$S\subset P_n$$</p>
<p>The stabilizer set establishes valid codewords for a state if the equation $$s\left|\psi\right\rangle=\left|\psi\right\rangle,\;\;\;\foral... | g9520 | [
0.012808258645236492,
-0.022088970988988876,
-0.00235425285063684,
-0.04421296343207359,
0.06166190654039383,
-0.023356424644589424,
0.018394911661744118,
-0.038772404193878174,
-0.001981837907806039,
0.05932480841875076,
0.0017886252608150244,
0.026848193258047104,
-0.04599212855100632,
0... |
<p>Can anyone demonstrate how to get the answers to these questions? I'm just interested in the method I need to use in order to obtain the correct answer no matter what the values are.</p>
<p>Three small spheres are placed at fixed points along the x-axis, whose positive direction points towards the right.</p>
<p>Sp... | g9521 | [
0.08739786595106125,
-0.014830361120402813,
0.008920533582568169,
-0.025237470865249634,
0.0601162314414978,
0.03184366226196289,
0.027418529614806175,
-0.004215968772768974,
-0.022336211055517197,
0.03932647779583931,
-0.046994827687740326,
0.008300552144646645,
0.008519725874066353,
-0.0... |
<p>I have a airburst round with set amount of fragments with a certain shape inside my bullet. After a certain distance has travelled, a charge explodes in the back of the round disintegrating the shell and sending the fragments out in a forward cone.</p>
<p>My problem : </p>
<ol>
<li><p>Why do they shoot out in a c... | g9522 | [
0.03467617183923721,
-0.01879788376390934,
0.0006089248927310109,
0.006209198851138353,
0.06491194665431976,
0.029450813308358192,
-0.025020116940140724,
0.004662123043090105,
-0.043901387602090836,
-0.07115449756383896,
-0.01860964484512806,
0.005127308890223503,
0.08308356255292892,
0.00... |
<p>I would want to know what the differences between these two techniques in cristalography. I research on internet, but it is not clear to me what each one does. </p>
<ul>
<li>When it's better to use one and not the other? </li>
<li>What things that only one of them can give me and why? </li>
<li>In energy or securit... | g9523 | [
0.056981831789016724,
0.010825267992913723,
0.00190200365614146,
-0.005342408083379269,
0.0300318393856287,
-0.04992103949189186,
0.0076611717231571674,
0.02983902208507061,
-0.008370155468583107,
-0.004661512561142445,
0.032770268619060516,
0.00006884898175485432,
0.04800037294626236,
-0.... |
<p>I'm looking for something short of a molecular dynamics package, where I can build up simple geometric shapes with flexible linkages/etc and simulate the consequences of electrostatic repulsion between surfaces. Something, say, that would let me simulate billiards in a magnetic field. </p>
<p>Does anyone have goo... | g495 | [
0.07642440497875214,
-0.008617310784757137,
0.0038976536598056555,
-0.03248412162065506,
-0.013356668874621391,
0.02846047654747963,
-0.03495066985487938,
-0.041683126240968704,
0.018388258293271065,
-0.031231308355927467,
0.032623596489429474,
-0.02610364370048046,
0.035892046988010406,
-... |
<p>I was wondering if it was possible to project a magnified image on a wall without the need of focusing, so just by dimensioning the lenses right.</p>
<p>I know I have to use the principal of Maxwellian View for the illumination of the slide. However, there are a lot of parameters left and I can design a system that... | g9524 | [
0.021111853420734406,
0.03273601830005646,
0.02454814501106739,
0.014981388114392757,
-0.013709837570786476,
-0.017326125875115395,
-0.013582385145127773,
0.007811613380908966,
-0.057825423777103424,
0.019516294822096825,
0.021473964676260948,
0.022665847092866898,
0.01845454052090645,
-0.... |
<p>Can someone please explain the <a href="http://en.wikipedia.org/wiki/Sommerfeld_radiation_condition" rel="nofollow">Sommerfeld radiation condition</a> and what is the alternative non-reflecting boundary conditions for waveguides of general geometries?</p> | g9525 | [
0.0202636681497097,
-0.005566160660237074,
-0.021354731172323227,
-0.05930924788117409,
0.005441712681204081,
0.008102953433990479,
0.02969004586338997,
0.011224506422877312,
0.00044388865353539586,
0.0033813584595918655,
0.04447844997048378,
0.015766922384500504,
-0.024057846516370773,
0.... |
<p>Can anyone explain to me why we have had no major breakthroughs in the theory of quantum computation in the past 15 years?</p>
<p>Shor's algorithm set the standard, since then we've had Grover's algorithm and an improvement on the Deutsch–Jozsa algorithm. What quantum algorithms of practical value have been created... | g9526 | [
-0.011916426941752434,
0.04415164887905121,
0.019555767998099327,
0.006502616684883833,
-0.017697155475616455,
0.00010191557521466166,
0.061802104115486145,
0.09069962799549103,
-0.014763597398996353,
0.03445166349411011,
-0.004081803373992443,
0.00555923068895936,
0.07986347377300262,
0.0... |
<p>The <a href="http://www.iso.org/sites/JCGM/VIM/JCGM_200e.html" rel="nofollow">ISO VIM</a> defines them as:</p>
<blockquote>
<p><strong>measurement method:</strong>
generic description of a logical organization of operations used in a
measurement.</p>
<p><strong>measurement procedure:</strong> detailed de... | g9527 | [
0.04772889241576195,
-0.01984323374927044,
0.004303286783397198,
0.02336372807621956,
0.017757300287485123,
-0.03454894945025444,
0.029152842238545418,
0.031192360445857048,
0.0028946981765329838,
-0.01849145069718361,
-0.043879635632038116,
-0.05041651427745819,
0.018768073990941048,
0.03... |
<p>Currently accepted scientific theory says that all elements heavier than hydrogen, helium, and a little lithium have been created in supernova explosions.</p>
<p>My questions, specifically, is has anyone done the math to see if the observed amounts and the distribution of, the heavier elements in the universe agree... | g9528 | [
0.02464226633310318,
0.030359048396348953,
0.0021021035499870777,
-0.013250648975372314,
-0.035019855946302414,
0.042248353362083435,
-0.01895153895020485,
0.03374597057700157,
0.03178931400179863,
-0.05753838270902634,
-0.006535092834383249,
-0.05397700145840645,
0.040978241711854935,
0.0... |
<blockquote>
<p>In an isothermal process the temperature of a system remains constant but may or may not be similar to temperature of surroundings</p>
</blockquote>
<p>How is this possible?</p> | g9529 | [
0.04989989846944809,
-0.01886296458542347,
0.030500750988721848,
0.0030352729372680187,
0.01153494417667389,
0.01826467551290989,
-0.0463116392493248,
0.019691068679094315,
-0.0245650727301836,
-0.02078291028738022,
-0.059227198362350464,
0.061131373047828674,
0.017926044762134552,
0.02793... |
<p>Non-collinear magnetism and paramagnetism, are they the same thing?</p> | g9530 | [
-0.0027570254169404507,
-0.018951889127492905,
-0.016175350174307823,
-0.012464101426303387,
0.031779929995536804,
0.006356810685247183,
-0.0022938053589314222,
-0.03691042959690094,
-0.021956782788038254,
0.007035357411950827,
-0.042808886617422104,
-0.026858627796173096,
-0.065416477620601... |
<p>Manganese has five unpaired electrons, but Iron has four, then why is Iron ferromagnetic and Manganese paramagnetic?
What's that property I'm missing?</p> | g9531 | [
0.03194713965058327,
0.0008448914159089327,
-0.004972489550709724,
0.011643185280263424,
0.068501316010952,
0.02404305525124073,
0.019812218844890594,
0.03385751321911812,
-0.07329864054918289,
-0.016705412417650223,
-0.06871320307254791,
0.013337524607777596,
-0.01761871762573719,
0.00958... |
<p>An elevator goes up 180 m by first accelerating at a constant rate of 1.0 m/s2, then staying at a constant
speed of 9 m/s and then decelerating at a constant rate of -‐‑1.0 m/s2. How much time does it take the
elevator to go from bottom to top?</p>
<p>so i know that d = 180m
a = 1.0 m/$s^2$ for the first part
v = ... | g9532 | [
0.06254306435585022,
0.06325162202119827,
0.01098491158336401,
0.06521214544773102,
0.003597438335418701,
-0.03504641726613045,
0.04441231116652489,
0.024373875930905342,
-0.06572647392749786,
0.045207735151052475,
-0.059144679456949234,
0.0662006214261055,
-0.0050763534381985664,
0.001303... |
<p>scalars (spin-0) derivatives is expressed as:</p>
<p>$$\nabla_{i} \phi = \frac{\partial \phi}{ \partial x_{i}}$$</p>
<p>vector (spin-1) derivatives are expressed as:</p>
<p>$$\nabla_{i} V^{k} = \frac{\partial V^{k}}{ \partial x_{i}} + \Gamma^k_{m i} V^m$$</p>
<p>what is the expression for covariant derivatives ... | g9533 | [
-0.00009480597509536892,
-0.04767859727144241,
-0.03736323118209839,
0.0022016155999153852,
0.026436900720000267,
-0.007746904157102108,
0.0952720046043396,
-0.003562475321814418,
-0.027367765083909035,
0.05489778146147728,
-0.038897838443517685,
0.043471142649650574,
0.016586868092417717,
... |
<p>I have heard the term quantum leap to describe the (instantaneous?) transition from a higher energy orbital to a lower energy orbital. Yet, I understand that this transition time has now been quantified in certain experiments.</p>
<p>So, it is not a leap? Is the electron wavefunction defined during this transition?... | g9534 | [
0.03084646537899971,
0.02207178622484207,
0.002693485002964735,
-0.021198637783527374,
0.03253629803657532,
0.044716689735651016,
-0.007835938595235348,
0.00825093686580658,
0.012038160115480423,
-0.00534614035859704,
-0.06876975297927856,
0.030781937763094902,
0.043874435126781464,
-0.031... |
<p>If I have a positive charge of +q and a negative charge of -q that are set a distance of r apart from each other, their midpoint will have an electric potential of zero. However, if I put a test charge into this midpoint and release it, it will gain kinetic energy, and I am under the impression that it comes from so... | g9535 | [
0.08318663388490677,
0.01132969930768013,
-0.003192846430465579,
0.026283636689186096,
0.05363790690898895,
0.03070193901658058,
-0.019421765580773354,
0.04874569550156593,
-0.06790800392627716,
0.003364193020388484,
0.00523823918774724,
0.003634482389315963,
-0.02772153541445732,
-0.03399... |
<p>Assume there is an infinite grounded conducting plane in the $xy$-plane. Assume also that a point charge is being brought slowly from $z=\infty$ to $z=z_0$, slowly enough that the problem is treated electrostatically. This charge will induce charge distribution on the plane. Now, I want to know why the work done by ... | g9536 | [
0.06704659014940262,
0.05004201456904411,
-0.007881561294198036,
-0.01945754885673523,
0.07346965372562408,
0.02346024475991726,
0.03671657294034958,
0.029583238065242767,
-0.054175540804862976,
0.011357809416949749,
-0.052594054490327835,
-0.01957298256456852,
-0.030962739139795303,
0.022... |
<p><img src="http://i.stack.imgur.com/IDIYj.jpg" alt="Picture"></p>
<p>a mass hangs from three ropes (as shown in the Picture)</p>
<p>can someone pleas help me with this?</p> | g9537 | [
0.026102228090167046,
0.039711590856313705,
-0.0027847352903336287,
-0.07042859494686127,
0.04129156842827797,
0.056751564145088196,
-0.0388687439262867,
-0.01045799907296896,
-0.02695556730031967,
0.0015729835722595453,
0.009453224949538708,
-0.0357794389128685,
-0.0053907944820821285,
-0... |
<p>According to our current scientific knowledge, how certain is it that <a href="http://en.wikipedia.org/wiki/Heat_death_of_the_universe" rel="nofollow">heat death</a> shall be the ultimate fate of our universe, and why? Are there any serious hypotheses competing with heat death, and if such hypotheses exist, what are... | g9538 | [
0.03475051373243332,
-0.022023912519216537,
0.021046672016382217,
0.037993401288986206,
0.010186207480728626,
-0.022462831810116768,
0.013222002424299717,
0.024562396109104156,
0.014053654856979847,
-0.04718220606446266,
0.0339461974799633,
-0.024366144090890884,
0.06013907492160797,
0.006... |
<p>A particle's interaction (with anything it can interact with) can be thought of as it making a measurement of the physical quantity associated with the interaction, (e.g. electric field in case of the interaction between charged particles) and acting accordingly. To make a measurement one first needs a frame to mak... | g9539 | [
0.045890647917985916,
0.02582237869501114,
-0.0023078625090420246,
0.020127730444073677,
0.06435701251029968,
0.003502798266708851,
0.06461434066295624,
0.008578273467719555,
-0.01115479413419962,
-0.034700680524110794,
0.02872350811958313,
0.001607745885848999,
-0.04780856892466545,
0.038... |
<p>Phase space flow shares characteristics with fluid flow such as incompressibility by Liouville's theorem. Extending the similarities one might be curious, does phase space flow have a characteristic number like the Reynold's number? Moreover, can phase space flow exhibit the characteristics of turbulence? </p>
<p>I... | g9540 | [
0.02375275455415249,
-0.010592322796583176,
0.017171183601021767,
-0.0015007975744083524,
0.006750226020812988,
-0.008332065306603909,
-0.0032561353873461485,
-0.012138426303863525,
-0.0001647164608584717,
-0.02850075252354145,
-0.053629230707883835,
-0.01814495027065277,
-0.0273064095526933... |
<p>The common definition of "time" is a type of measurement, like size. But the sentence "size gets bigger" doesn't make any sense. Is "time slows down" an odd phrasing of "events occur more slowly" or is there a deeper meaning to the phrase?</p> | g9541 | [
0.07578040659427643,
0.08761585503816605,
0.000782282673753798,
-0.06972148269414902,
0.02628481015563011,
0.00017378061602357775,
0.05621591582894325,
0.025095706805586815,
-0.031644053757190704,
-0.047111447900533676,
-0.04375257343053818,
-0.05181703716516495,
-0.0037211868911981583,
0.... |
<p>Let's have interaction between gravitational and scalar real fields. For an action of gravitational field in vacuum I add term $S_{m} = \int d^{4}x\sqrt{-g}L_{m}$, where
$$
L_{m} = \frac{1}{2}g^{\mu \nu}\partial_{\mu}\varphi \partial_{\nu} \varphi - V(\varphi )
$$
So the variation $\delta S_{m}$ must give $\frac{1}... | g9542 | [
0.04410437121987343,
0.009585307911038399,
-0.020640600472688675,
0.005750840995460749,
0.05021808668971062,
0.034462083131074905,
0.036145079880952835,
-0.017637522891163826,
-0.10293812304735184,
-0.025340143591165543,
-0.03446578606963158,
0.062497057020664215,
-0.0031029479578137398,
-... |
<p>I read in a book just now that says:</p>
<blockquote>
<p>[...] but it was not explained until the invention of quantum field theory by Richard Feynmann [<a href="http://en.wikipedia.org/wiki/Sic"><em>sic</em></a>] and others in the 1940's.</p>
</blockquote>
<p>I have been under the impression that it was Paul Di... | g9543 | [
0.07414828985929489,
0.0622267983853817,
0.010165260173380375,
0.00044754453119821846,
0.06589306145906448,
-0.039577603340148926,
0.03252389281988144,
-0.005025862716138363,
-0.00271657295525074,
-0.03880618140101433,
-0.06089961901307106,
0.0006225782562978566,
-0.01828004978597164,
0.00... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.