question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>I'm reading a script on atomic physics, and there's a chapter on irreducible tensors. I can't understand the meaning of "transform among themselves" in this context:</p>
<blockquote>
<p>An arbitrary rotation of the coordinate frame will transform the
tensor $T$ into a tensor $T'$, whose components $T_{ij}'$ are... | g13692 | [
0.01601916365325451,
0.006118034012615681,
0.0072226496413350105,
-0.03994123637676239,
0.05103481188416481,
-0.023363523185253143,
0.029933812096714973,
0.05207562446594238,
0.00632813386619091,
-0.011896318756043911,
-0.034195829182863235,
0.05816357582807541,
0.024277610704302788,
-0.06... |
<p>The reasons for choosing length, mass, time, temperature, and amount as base quantities look (at least to me) obvious. What I'm puzzling about is why current (as opposed to resistance, electromotive force, etc.) and luminous intensity (as opposed to illuminance, emittance, etc.) were chosen to be base quantities. Do... | g13693 | [
0.02602548338472843,
0.031080055981874466,
-0.020090969279408455,
-0.06181824207305908,
0.038421306759119034,
0.015124646946787834,
0.07467824220657349,
-0.024611391127109528,
-0.013355027884244919,
-0.014049554243683815,
-0.006031190510839224,
-0.018117276951670647,
0.03927146643400192,
0... |
<p>Consider the following system. The given friction coefficients are for static. Let $g=10$ (meter per square second).</p>
<p><img src="http://i.stack.imgur.com/8zp7O.png" alt="enter image description here"></p>
<p>If the $F(t)=10t$, for example, determine the friction forces $f_{AB}(t)$ (between the boxes $A$ and $... | g13694 | [
0.05376504361629486,
0.05699772387742996,
0.004938043188303709,
0.002985551953315735,
0.068577840924263,
-0.023546095937490463,
0.04280516132712364,
-0.01691923290491104,
-0.030430464074015617,
-0.07645367085933685,
-0.05307195335626602,
-0.00010758144344436005,
0.0242798812687397,
0.00941... |
<ul>
<li>I placed a box in front of a plane mirror</li>
<li>I looked at the image and smudged a bit of Vaseline on the mirror as a mark to indicate where I thought where the virtual image was. </li>
<li>After that, I repositioned myself at different places of my room. One thing I noticed was that I the image was changi... | g13695 | [
-0.021941032260656357,
-0.022072484716773033,
-0.0036353105679154396,
-0.03819623962044716,
0.06256724894046783,
0.003382481634616852,
0.019474897533655167,
0.04061169922351837,
-0.007746475748717785,
-0.014831171371042728,
0.013577712699770927,
-0.02355695143342018,
0.06391243636608124,
0... |
<p>a friend of mine thinks that by buying a product called <a href="http://www.humanfirewall.com/orderrayguard.htm" rel="nofollow">rayguard</a> he can effectively shield against electrosmog.</p>
<p>On the website, there are multiple evidences that this might work. However the product seems to be just created of one pl... | g13696 | [
0.0059181516990065575,
0.015930568799376488,
0.022390995174646378,
0.008806968107819557,
0.041644733399152756,
0.005845506675541401,
-0.026000680401921272,
0.026679234579205513,
0.030962059274315834,
-0.02452857233583927,
0.039558179676532745,
0.041468966752290726,
-0.01137031801044941,
-0... |
<p>I am curious as to how much voltage should be applied to create a specific charge. Is there a formula to calculate it, and what are the parameters that can affect the relation between voltage and charge created in that object?</p>
<p>P.S: I haven't taken course on this subject, so I don't know the details of this s... | g13697 | [
0.025955677032470703,
0.017802732065320015,
-0.003706802846863866,
0.006368118803948164,
0.041506096720695496,
0.0007883403450250626,
-0.01151336170732975,
0.04435526579618454,
-0.02762087807059288,
0.01577085256576538,
-0.026014259085059166,
0.06919104605913162,
0.022297626361250877,
0.04... |
<p>I seem to be confused about the nature of forces as vectors, in the basic Newtonian mechanics framework. </p>
<p>I know what a vector is as a mathematical object, an element of $R^3$. I understand that if a vector is drawn in a usual physical way as an arrow in space, it can be seen as a mathematical vector by tran... | g13698 | [
0.021607136353850365,
0.0010999591322615743,
0.0034076455049216747,
-0.0015723153483122587,
0.020380962640047073,
-0.03100648522377014,
0.04278988018631935,
-0.021961567923426628,
-0.0673874020576477,
-0.031759705394506454,
-0.0028187150601297617,
-0.021192878484725952,
0.022788111120462418,... |
<p>Here's an explanation from a book that I read:</p>
<p><img src="http://i.stack.imgur.com/9q7I7.png" alt="enter image description here"></p>
<p>Now, I have a few problems with this explanation as well as with the "cone method". I guess that all my problems boil down to the concept of infinitesimal.</p>
<ol>
<li><p... | g13699 | [
0.050280213356018066,
-0.0011430633021518588,
-0.003337239846587181,
-0.022482942789793015,
0.057242631912231445,
0.028885716572403908,
0.043090131133794785,
0.010841461829841137,
-0.0385148860514164,
0.025254718959331512,
-0.007063989527523518,
-0.024620095267891884,
0.05311816185712814,
... |
<blockquote>
<p>A ball of mass 0.37 kg is thrown upward along the vertical with a
initial speed of 14 m / s, and reaches a maximum height of 8.4 m.
a) What is the work done by air resistance on the ball? b) Assuming that the
air resistance performs roughly the same job during the descent,
Calculate the speed... | g13700 | [
0.035893313586711884,
0.024681318551301956,
0.007833282463252544,
0.03916750103235245,
0.00505819683894515,
0.04920847713947296,
0.0801662877202034,
0.015219014137983322,
-0.06462637335062027,
0.030170250684022903,
-0.07736493647098541,
0.03578244894742966,
-0.0020740744657814503,
-0.01736... |
<p>With <a href="http://en.wikipedia.org/wiki/Jones_calculus" rel="nofollow">Jones vectors and matrices</a> one can describe the change in polarization of a EM wave. What is the convention of the reference coordinate system; Is it fixed or does it change whenever the direction of the wave changes?</p>
<p>In other word... | g13701 | [
-0.046048592776060104,
-0.005534744821488857,
-0.007305494509637356,
-0.0017680064775049686,
0.04107042774558067,
-0.02394385263323784,
0.01829228177666664,
-0.002376123098656535,
-0.008493996225297451,
0.005149582866579294,
0.014810115098953247,
0.07401444762945175,
0.035196397453546524,
... |
<p>Conformal gravity is an "alternative" theory of gravity, where instead of using the Einstein-Hilbert action composed of the Ricci scalar, the square of the conformal Weyl tensor is used. It was originally designed to arrive at the inflationary cosmological models without the use of dark energy. </p>
<p>However, it... | g13702 | [
0.032497357577085495,
-0.007476854603737593,
0.0171491801738739,
-0.015525954775512218,
0.03507647663354874,
0.03387673944234848,
-0.010779572650790215,
-0.01961010880768299,
-0.007373513653874397,
-0.010361366905272007,
0.03406894579529762,
-0.007335154339671135,
0.05976034328341484,
0.04... |
<p>I don't understand the solutions to a problem about blackbody radiation and was wondering if anybody could help me out.</p>
<p>Here is the question:</p>
<blockquote>
<p>The sun can be considered as a blackbody radiation source at temperature
T = 5778 K. Radiation from the sun which is incident on the earth is ... | g13703 | [
0.024617742747068405,
0.04587642475962639,
0.01796223782002926,
0.009599292650818825,
0.008248796686530113,
0.010882733389735222,
0.038474392145872116,
0.023565882816910744,
-0.011227493174374104,
0.0017582286382094026,
-0.02415083721280098,
0.09837793558835983,
0.027040496468544006,
-0.00... |
<p>I think this is analogues for the <a href="http://en.wikipedia.org/wiki/Woodward_effect" rel="nofollow">Woodward effect</a>, but macroscopic:</p>
<p>We assume a spacecraft consisting of a broomstick, a donut and lots of gear for storing and transfering mechanical energy.
Take the donut, spin it till the outer edge ... | g13704 | [
0.016366079449653625,
0.06136558577418327,
-0.004069283604621887,
0.030177343636751175,
0.004250113386660814,
0.0464811809360981,
0.04552660137414932,
0.011873744428157806,
-0.044124022126197815,
-0.024986552074551582,
-0.006629426032304764,
-0.0305330827832222,
0.038508836179971695,
0.032... |
<p>I am reading Smolin's book <a href="http://rads.stackoverflow.com/amzn/click/0195126645" rel="nofollow">Life of the Cosmos</a>. One part which I can hardly understand is the argument for cosmological natural selection as a scientific principle.</p>
<p>Smolin keeps on saying that cosmological natural selection is a ... | g13705 | [
0.03645072877407074,
0.028066886588931084,
0.040490467101335526,
0.0227406844496727,
0.020976124331355095,
0.061093296855688095,
0.0062022036872804165,
-0.0036377711221575737,
0.011176479049026966,
0.04079547896981239,
-0.002760372357442975,
-0.004718147683888674,
0.045024290680885315,
0.0... |
<p>Why is it that creation and annihilation operators ($a_+$ and $a_-$) can only be defined for the problem of quantum harmonic oscillator and nothing else? Can any other bound state problem be solves using $a_+$ and $a_-$?</p> | g13706 | [
0.0016411428805440664,
0.01185605302453041,
0.008331848308444023,
-0.002210047794505954,
0.006760940887033939,
-0.0012108072405681014,
0.012805589474737644,
0.05470511317253113,
0.018701400607824326,
-0.015542445704340935,
-0.0109450938180089,
0.0024989109952002764,
0.020353712141513824,
0... |
<p>For the Klein Gordon nonlinear equation,</p>
<p>$$ u_{tt}- \Delta u +f(u)=0,$$</p>
<p>how could I use Noether's theorem to prove that there is a conserved quantity? I.e.,</p>
<p>$$ (\Pi _{k} )_{t} - \rm div(j_{k})=0 $$
for $k=0,1,2,3$, where</p>
<p>$$ \Pi _{k} = \int _{R^{3}}p(x,y,z,t)dv $$
is the density of fo... | g13707 | [
0.03795266151428223,
-0.025502126663923264,
0.0020831420551985502,
0.006997052580118179,
0.041432201862335205,
0.031774330884218216,
-0.03626655414700508,
0.02339128404855728,
-0.033251550048589706,
-0.00011622616148088127,
-0.051512621343135834,
-0.044357527047395706,
-0.04537222161889076,
... |
<p>Firstly I think I am right in saying that TV broadcast are sent via electromagnetic waves which means they are sent via photons, how is that even possible?</p>
<p>And then the main questions, how can you broadcast such large amounts of data over the airwaves and produce photorealistic TV and a PC cannot.</p>
<p>I ... | g13708 | [
-0.004589081276208162,
0.06227850168943405,
-0.0016658967360854149,
0.02210942842066288,
-0.03218807280063629,
-0.009384813718497753,
-0.024722419679164886,
0.005054830573499203,
-0.013945118524134159,
-0.06336508691310883,
-0.003786405548453331,
0.03635825961828232,
0.05255383253097534,
0... |
<p>As we know that induction cooker works on the principal of induction of current in a conducting plate. So I just wanted to know what will happen if we place salt water in a plastic container on the induction cooker will it get hot as it is also a conductor or nothing will happen?</p> | g13709 | [
0.04077822342514992,
0.06215488910675049,
0.016770079731941223,
-0.036637090146541595,
0.012919518165290356,
0.03056461550295353,
-0.031072190031409264,
0.02885173261165619,
-0.0458843857049942,
-0.006006238516420126,
-0.009913346730172634,
0.11724545061588287,
-0.06229714676737785,
0.0373... |
<p>I'm a third year mathematics undergrad, and have just started the module General Relativity and spacetime geometry, I also have a keen interest in black holes.</p>
<p>However I would like to know why and how the mass of the Kerr black hole is proportional to it's angular momentum, and also inversely proportional to... | g13710 | [
0.030491160228848457,
-0.04649895802140236,
-0.0023062361869961023,
-0.014441311359405518,
0.014970115385949612,
0.0399041511118412,
0.05203079804778099,
0.038823772221803665,
-0.02765354886651039,
0.053240012377500534,
0.03132978081703186,
-0.020565640181303024,
0.03759576007723808,
0.009... |
<p>I have a circuit that has 4 wires and 2 following each other <a href="http://en.wikipedia.org/wiki/Toffoli_gate" rel="nofollow">Toffoli gates</a>.</p>
<p>I have permutation matrix for each Toffoli gate (A and B).</p>
<p>Do I have to multiply that 2 matrices to get the entire permutation matrix of that 2 Toffoli ga... | g13711 | [
-0.0005955295637249947,
0.04665601998567581,
-0.011218192987143993,
-0.022177422419190407,
0.026750575751066208,
-0.09657298028469086,
0.007577370852231979,
0.0010556239867582917,
-0.03562212362885475,
0.009405987337231636,
-0.04628751054406166,
0.02142646536231041,
0.00639263354241848,
0.... |
<p>On <a href="http://en.wikipedia.org/wiki/Einstein_notation" rel="nofollow">Einstein notation</a> with multiple indices: For example, consider the expression:</p>
<p>$$a^{ij} b_{ij}.$$</p>
<p>Does the notation signify,</p>
<p>$$a^{00} b_{00} + a^{01} b_{01} + a^{02} b_{02} + ... $$</p>
<p>i.e. you sum over every ... | g13712 | [
-0.00027792039327323437,
0.018813956528902054,
0.004132166970521212,
0.02088102512061596,
0.024182572960853577,
-0.042848218232393265,
0.04691239073872566,
0.023808730766177177,
-0.006681876257061958,
0.012623980641365051,
-0.03514736145734787,
0.02747238241136074,
0.014864795841276646,
-0... |
<p>in my atomic physics lecture notes it is said that depending on the values of the exchange operator $K_{ij}$ there can be different kinds of magnetism, say, ferromagnetism and antiferromagnetism, how can I see that?</p> | g13713 | [
-0.02818215824663639,
0.048931412398815155,
-0.022784722968935966,
-0.018495401367545128,
0.043533653020858765,
0.0015000627608969808,
-0.025165965780615807,
0.026552889496088028,
0.03324352204799652,
0.004098272416740656,
-0.02603737823665142,
0.0363151840865612,
0.0290579404681921,
0.018... |
<p>Examining the following graph, I am trying to understand the power plot. The power appears to take on a negative value when the current changes direction or the voltage changes polarity. Negative power does not make sense to me. In a proper representation of the power curve shouldn't the power remain above the dotte... | g13714 | [
0.003739429172128439,
-0.007673340383917093,
-0.03624695912003517,
0.00322278356179595,
0.015628311783075333,
0.01382497139275074,
-0.023020025342702866,
-0.03153173252940178,
-0.031724099069833755,
-0.0030220807529985905,
0.05286116153001785,
0.03115609847009182,
0.033434923738241196,
0.0... |
<p>I'm not sure if this is the best place to ask this question, but as it's related to the terminology of nuclear physics I thought it would probably be a logical place to start.</p>
<p>I'm currently writing my thesis, and in the section on radioactive decay I talk about the mass number and activity of radionuclides. ... | g13715 | [
0.03306128457188606,
-0.03111141547560692,
0.009986130520701408,
-0.035599805414676666,
0.048545923084020615,
-0.008218116126954556,
0.0324857123196125,
0.07508688420057297,
0.031912676990032196,
-0.027986427769064903,
0.031363073736429214,
0.024656984955072403,
0.09129729866981506,
0.0052... |
<p>We know that the molecule of hot water($H_2O$) has more energy than that of cold water (temperature = energy)
and according to Einstein relation $E=mc^2$ ,this extra energy of the hot molecule has a mass.
Does that make the hot molecule heavier?</p> | g13716 | [
0.04415161535143852,
-0.01260374579578638,
0.015306389890611172,
-0.019167691469192505,
-0.009274185635149479,
0.03342919796705246,
-0.0484437495470047,
0.03592599928379059,
-0.05243980884552002,
-0.023329151794314384,
-0.0053789131343364716,
-0.08022543787956238,
0.018129082396626472,
0.0... |
<p>If I use a telescope to observe a plane in the sky, how can I find the altitude of the plane(altitude of the plane with respect to the ground)?</p> | g13717 | [
-0.0024651845451444387,
0.0005514414515346289,
0.00020485233108047396,
-0.008752206340432167,
0.01124588493257761,
0.045692820101976395,
-0.07400532811880112,
0.004919042810797691,
-0.04207215830683708,
0.0023736953735351562,
-0.005126499105244875,
-0.005138890817761421,
-0.00205772113986313... |
<p>Supersymmetry should cancel the radiative corrections to the Higgs mass and solve the hierarchy problem. If Supersymmetry would be unbroken, would the higgs mass be 0?</p> | g13718 | [
0.08471617102622986,
0.02112804353237152,
0.006472461391240358,
0.02625264786183834,
0.008739674463868141,
0.04862865433096886,
-0.00408423924818635,
0.11061301082372665,
-0.0034656364005059004,
0.009662386029958725,
-0.01872282288968563,
-0.008939946070313454,
-0.03110748529434204,
0.0775... |
<p>Suppose we have
$$[Q^a,Q^b]=if^c_{ab}Q^c$$
where Q's are generators of a Lie algebra associated a SU(N) group. So Q's are traceless. Also we have
$$[P^a,P^b]=0$$
where P's are generators of a Lie algebra associated to an Abelian group. We have the following relation between these generators
$$[Q^a,P^b]=if^c_{ab}P^... | g13719 | [
0.011654906906187534,
-0.014295479282736778,
-0.025971217080950737,
-0.05531497672200203,
0.03131299838423729,
-0.022131238132715225,
0.018879707902669907,
0.003781337523832917,
-0.016536394134163857,
0.0024464584421366453,
-0.037848733365535736,
0.018186267465353012,
-0.0022857303265482187,... |
<p>Consider a coupled harmonic oscillator with their position given by $x_1$ and $x_2$. Say the normal coordinates $x_{\pm}={1\over\sqrt{2}} (x_1\pm x_2)$, in which the harmonic oscillators decouple, exist.</p>
<p>When you quantize this theory, the corresponding operators are $\hat x_1,~
\hat x_2,~ \hat x_{\pm}$. The ... | g13720 | [
-0.011186769232153893,
-0.01493032556027174,
-0.010595879517495632,
-0.03295637294650078,
0.032122235745191574,
-0.030807722359895706,
0.0304668378084898,
0.022578734904527664,
0.06898195296525955,
0.0367143340408802,
-0.029216229915618896,
-0.03439067304134369,
-0.012113082222640514,
-0.0... |
<p>If someone has short or long sight, is it possible to tune image on a computer monitor in such way, that a person could see it sharp as if they were wearing glasses? If not, will 3d monitor make it possible?</p> | g486 | [
-0.005836624186486006,
0.02421623095870018,
0.007774458732455969,
0.009157627820968628,
-0.042888909578323364,
0.006220005918294191,
-0.0042688376270234585,
-0.00003421853398322128,
0.02084922231733799,
-0.013191056437790394,
0.04842570051550865,
0.06396448612213135,
0.037183091044425964,
... |
<p>Reynolds-averaged Navier–Stokes equations (RANS) is one of the approaches to turbulence description. Physical quantities, like for example velocity $u_i$, are represented as a sum of a mean and a fluctuating part:</p>
<p>$$
u_i = \overline{u_i} + u'_i
$$</p>
<p>where the Reynolds averaging operator $\overline{\cdo... | g13721 | [
-0.03294799104332924,
-0.025522692129015923,
-0.016438713297247887,
-0.04389103129506111,
0.0440763495862484,
-0.03044363111257553,
0.08045592904090881,
-0.01734558492898941,
-0.03357619047164917,
-0.034276824444532394,
0.03485172241926193,
-0.0230718944221735,
0.0084538534283638,
0.020865... |
<p>I was told that if a plane takes less time to travel from the China to US as opposed to the other direction due to rotation of the earth. I suspect this is incorrect however. </p>
<p>From this scenario I came up with the following thought experiment. Imagine two people sitting on a train. One person is sitting with... | g13722 | [
0.0362178310751915,
0.05905371531844139,
0.009053409099578857,
-0.027439862489700317,
0.03493158146739006,
0.06387852877378464,
0.07521882653236389,
-0.026395166292786598,
-0.053541913628578186,
-0.01568908430635929,
0.04250907897949219,
-0.004564821720123291,
0.04847070574760437,
-0.00398... |
<p>I have to fit some data to a power law</p>
<p>$$ F=\alpha q^{\beta}$$</p>
<p>being $q$ and $F$ the experimental data points. What I usually do is taking logs so that</p>
<p>$$ \ln(F) = \beta \ln(q)+\ln(\alpha)$$</p>
<p>and apply least squares with uncertainties in both variables. How may I approach this in the c... | g13723 | [
0.08496087789535522,
-0.04914186894893646,
-0.028560509905219078,
-0.046980444341897964,
0.07928714156150818,
-0.010362771339714527,
-0.015345800668001175,
-0.04822197183966637,
-0.04543010890483856,
0.003739491803571582,
0.02233249507844448,
-0.0021951082162559032,
-0.018897397443652153,
... |
<p>A recent <a href="http://what-if.xkcd.com/7/" rel="nofollow">XKCD What-if</a> article mentions the situation where each additional kilogram of cargo to LEO requires an additional 1. 3 kilograms of fuel, which in turn requires fuel to carry (simplification). I wonder then, if an additional half-kilo object, <a href="... | g13724 | [
-0.04663355275988579,
0.044762544333934784,
-0.006899412255734205,
-0.041119534522295,
-0.03641592338681221,
-0.015610712580382824,
-0.037534311413764954,
0.0004958096542395651,
-0.08529342710971832,
0.024786055088043213,
0.006251493003219366,
-0.09568246454000473,
0.002413678215816617,
-0... |
<p>Suppose there is a particle in space. When we measure the position of that particle, we get a particular value with a probability that can be calculated from the wave function. But, according to the <a href="https://en.wikipedia.org/wiki/Copenhagen_interpretation" rel="nofollow">Copenhagen interpretation</a>, where ... | g13725 | [
0.02657073549926281,
0.024139421060681343,
-0.013576095923781395,
-0.10869573801755905,
-0.0019995933398604393,
0.012487786822021008,
0.02763170562684536,
0.07058411836624146,
-0.051078397780656815,
-0.03339776024222374,
-0.07530715316534042,
-0.030610341578722,
0.03322922810912132,
-0.005... |
<p>I do not understand how any state in Hilbert Space $\mathcal{H}=\mathcal{H}_A\otimes\mathcal{H}_B$ of dimension $\text{dim}(\mathcal{H}_A)\times\text{dim}(\mathcal{H}_B)$ can be decomposed in the Schmidt basis when the Schmidt basis has size $\text{min}\{\text{dim}(\mathcal{H}_A),\text{dim}(\mathcal{H}_A)$}.</p>
<p... | g13726 | [
0.011296250857412815,
-0.029668128117918968,
-0.0039742873050272465,
-0.03973862901329994,
-0.04584503546357155,
-0.05696302279829979,
0.01377933006733656,
0.035115715116262436,
0.0329667404294014,
-0.012543557211756706,
-0.046113159507513046,
-0.042727354913949966,
-0.006678338162600994,
... |
<p>I had never seen this system until today, and I'm really confused. I've read the wikipedia article about it but I still don't know how to change between this and the international system. For example, studying emision of radiation of an electric dipole: $\wp$, one gets to an equation for the magnetic potential given... | g13727 | [
-0.03440086171030998,
0.03794465214014053,
-0.030594877898693085,
-0.0466042086482048,
0.03750678151845932,
0.026207974180579185,
0.016266394406557083,
0.01955713890492916,
-0.013611314818263054,
0.028755132108926773,
-0.013721124269068241,
0.08136247098445892,
0.05379100516438484,
-0.0105... |
<p>When I go to, for example, a museum I try to take some pictures.</p>
<p>Sometimes the museum staffs forbid me to use a flash. Do you know the reason? I don't think it is related to photo-electric effect, right?</p> | g13728 | [
-0.03718378022313118,
0.07782673090696335,
-0.007924909703433514,
0.03604112192988396,
0.03708955645561218,
0.0009193560108542442,
0.0715036541223526,
0.06231960654258728,
0.00735310697928071,
-0.026363223791122437,
-0.0024257434997707605,
-0.041542861610651016,
-0.0051326751708984375,
0.0... |
<p>I'm reading this book "Introduction to Quantum Fields in Classical Backgrounds" by Mukhanov & Winitzki, and there in the chapter 8 "The Unruh Effect" they introduce 3 reference frames.</p>
<p><strong>Laboratory Frame</strong>: "is the usual inertial reference frame with the coordinates $(t,x,y,z)$".</p>
<p><st... | g13729 | [
0.04538590833544731,
0.02123563177883625,
0.00858728401362896,
-0.014264213852584362,
0.07042364776134491,
0.04223782569169998,
0.049547914415597916,
0.060672540217638016,
-0.02278425358235836,
0.014850911684334278,
0.0032297573052346706,
0.0022619247902184725,
-0.015230998396873474,
0.007... |
<p>Newton's Third Law states that <em>Whenever any force is exerted by a body#1 on any other body#2, another force which is equal in magnitude and opposite in direction is exerted on body#1 by body#2.</em> In theory, suppose a boy is pushing a rock heavier than him on ice. Due to the relative lack of friction, the boy ... | g13730 | [
0.025428378954529762,
0.07772503048181534,
0.022844675928354263,
-0.033118050545454025,
0.08752370625734329,
0.07737643271684647,
-0.014713137410581112,
0.021319998428225517,
-0.04412494972348213,
0.00022287220053840429,
-0.06510494649410248,
-0.035625360906124115,
-0.007239006459712982,
-... |
<p>Suppose one has a circuit consisting of an inductor $L$ and resistor $R$ in series where $L$ and $R$ are known, passes an alternating voltage of frequency $\omega$ through it and that one wishes to calculate the mean power dissipated in the resistor.</p>
<p>Let the RMS voltage across the series combination be $V_0$... | g13731 | [
0.002464671153575182,
-0.047217972576618195,
0.0015239209169521928,
-0.014348289929330349,
0.0021897493861615658,
-0.07082522660493851,
0.024022838100790977,
0.02600874751806259,
-0.004683682229369879,
0.02046389691531658,
-0.02457292564213276,
0.07170843333005905,
0.021891644224524498,
0.... |
<p>Found this at the gas station yesteday - got me thinking...</p>
<p><img src="http://i.stack.imgur.com/51Kz3.jpg" alt="enter image description here"></p> | g13732 | [
-0.028355011716485023,
-0.014844224788248539,
-0.0480235256254673,
-0.029287908226251602,
0.005316998343914747,
-0.06593892723321915,
-0.03612767159938812,
0.07502326369285583,
-0.026224367320537567,
-0.01774662733078003,
0.02932014688849449,
-0.053155601024627686,
0.0018728218274191022,
-... |
<p>While studying about band theory of semiconductors, I observed that when the electrons were excited from the valence band to the conduction band, they left behind holes in the valence band. From my existing knowledge, I believe that the valence electrons alone occupy the valence band which tells me the valence band ... | g13733 | [
0.02115766704082489,
0.01978110522031784,
-0.015638524666428566,
-0.008661177940666676,
0.03620617091655731,
0.07931942492723465,
0.018685689195990562,
0.02354886382818222,
0.07141561806201935,
-0.007394794840365648,
0.02560693398118019,
0.06069489195942879,
-0.0068781147710978985,
0.00957... |
<p>I'm not very knowledgeable about physics generally, but know that nothing can escape a black hole's gravitational pull, not even light (making them nearly invisible?). </p>
<p>My question is: <strong>What has been obtained from direct observation of a black hole to prove their existence?</strong> Please note that I... | g16 | [
0.011284894309937954,
0.026313282549381256,
0.024534771218895912,
-0.0026069122832268476,
0.05347450077533722,
0.030932648107409477,
-0.011126519180834293,
0.0392390675842762,
-0.023543937131762505,
-0.029807841405272484,
0.008526922203600407,
-0.017329253256320953,
0.049814604222774506,
0... |
<p>In <a href="http://davidsenouf.com/wp-content/uploads/2012/01/The-quaternion-group-and-modern-physics-Girard.pdf">The Quaternion Group and Modern Physics by P.R. Girard</a>, the quaternion form of the general relativistic equation of motion is derived from</p>
<p>$du'/ds = (d a / d s ) u {a_c}^* + a u ( d {a_c}... | g13734 | [
-0.038254786282777786,
0.03090083599090576,
-0.0062530203722417355,
-0.0032147683668881655,
0.05561678111553192,
0.02430236153304577,
0.07042521238327026,
-0.04639240354299545,
-0.031504690647125244,
-0.029991107061505318,
0.005239980295300484,
-0.02931654080748558,
0.03497406095266342,
-0... |
<p><strong>Introduction</strong></p>
<p>I have the following data for a galaxy: apparent magnitude in $U,B$ and $V$ Johnson photometric system:</p>
<p>$$m_{U}=17.51 \\m_{B}=17.08 \\m_{V}=16.74 $$</p>
<p>The galaxy is such that the galactic hydrogen column has $N(H)=6 \cdot10^{22} \mbox{ cm}^{-2}$. I have to take int... | g13735 | [
0.01115375105291605,
-0.047468941658735275,
-0.010753818787634373,
-0.04661636799573898,
0.010688086040318012,
0.002645617350935936,
0.012306608259677887,
-0.004295384045690298,
-0.02112676203250885,
0.015486915595829487,
-0.017164869233965874,
0.06870248913764954,
0.041954994201660156,
0.... |
<p>I'm reading about the second quantization formalism. I can see the advantages of using number states to represent multiparticle states. Here's my question:</p>
<p>Let's say we're given a single-particle basis of plane waves with spins (so each particle can be described by some wavevector $k$ and some spin $\sigma$)... | g13736 | [
0.008755505084991455,
0.04864059016108513,
-0.011372855864465237,
-0.03885367140173912,
0.05153634399175644,
-0.018165186047554016,
0.008339515887200832,
0.03709839656949043,
0.01928398758172989,
-0.0076920706778764725,
-0.05223527178168297,
-0.01110424567013979,
0.01978437975049019,
0.013... |
<p>In a nucleus, the strong nuclear force causes interactions between protons and protons, between neutrons and neutrons, and between protons and neutrons. What do we know about this interaction?</p>
<p>Related:</p>
<ul>
<li><a href="http://physics.stackexchange.com/questions/20003/why-dont-electrons-crash-into-the-n... | g13737 | [
0.029040303081274033,
0.08566984534263611,
-0.024378066882491112,
-0.02110004611313343,
0.09126269072294235,
0.021967537701129913,
-0.03126314654946327,
0.025236789137125015,
-0.006232847925275564,
-0.07023277133703232,
-0.01842663623392582,
-0.00386825785972178,
-0.04771639406681061,
0.02... |
<ol>
<li><p>In spin ice systems magnetic monopole-like excitations are sources or sinks of $H$, not the $B$ field, why is that? Is it because the strings carries magnetic moment $M$ and not solenoidal $B$ filed like the Dirac string.</p></li>
<li><p>How is it different from Dirac construction of magnetic monopole?</p><... | g13738 | [
0.016214504837989807,
0.059960465878248215,
-0.013463149778544903,
-0.029036087915301323,
0.08266809582710266,
0.03184511885046959,
0.057369790971279144,
0.051585473120212555,
-0.0135842589661479,
-0.006715833675116301,
-0.08590057492256165,
0.00895311962813139,
0.0004146837454754859,
0.01... |
<p>My question is specifically about how to use sources? For an interacting theory with one field, one puts a $J(x)\phi(x)$ term in the exponential in the path integral for $W[J]$. I now have two different fields ($\phi_1(x)$ and $\phi_2(x)$) and a number of interactions in the Lagrangian involving a combination of fie... | g13739 | [
0.04578644037246704,
0.022429609671235085,
0.0005699293105863035,
-0.02686030976474285,
0.0346810519695282,
-0.014599681831896305,
0.011142815463244915,
0.008423597551882267,
-0.03259877488017082,
0.02411261945962906,
-0.01706209033727646,
0.019055200740695,
0.013553695753216743,
0.0259237... |
<blockquote>
<p><em>Suppose we have two masses, $m_1$ and $m_2$, where $m_2$ is at rest, and $m_1$ is headed directly towards $m_2$. I would like to write the ratio of the masses as a function of the angle.</em> </p>
</blockquote>
<p>Using Conservation of Energy, Conservation of Momentum, and applying the Law of Cos... | g429 | [
0.036896221339702606,
-0.05477968230843544,
0.0040188925340771675,
-0.004969235975295305,
0.05194932967424393,
-0.013320728205144405,
0.014560936018824577,
0.005363804753869772,
-0.03260987624526024,
0.07205887883901596,
0.05268722027540207,
0.02168716862797737,
0.020614685490727425,
0.010... |
<p>In the hierarchy of theories, first comes hamiltonian theory, from which one deduces kinetics theory, and at last thermodynamics and fluid theories. From a kinetics point of view, entropy and temperature are macroscopic parameters with no equivalent at the microscopic level. However, thermodynamical entropy and inf... | g13740 | [
0.016861334443092346,
0.009360001422464848,
-0.015814129263162613,
-0.02561364509165287,
0.008420178666710854,
-0.01719662919640541,
-0.009338337928056717,
0.016115253791213036,
-0.02387600764632225,
0.047874536365270615,
0.024741098284721375,
0.02353096939623356,
0.017206314951181412,
0.0... |
<p>Two very intriguing papers recently appeared on the arXiv, claiming that one can use "superqubits" -- a supersymmetric generalization of qubits -- to violate the Bell inequality by more than standard quantum mechanics would allow. (That is, they claim one can violate the Tsirelson bound, which says that the CHSH ga... | g13741 | [
0.02947697974741459,
0.09123172610998154,
0.017008332535624504,
0.03085051104426384,
0.015399216674268246,
-0.014142651110887527,
0.00017457817739341408,
0.015827476978302002,
-0.007344807498157024,
-0.024889519438147545,
-0.03308229148387909,
-0.03149021789431572,
-0.023581279441714287,
0... |
<p>Suppose you have an object with zero for the value of all the derivatives of position. In order to get the object moving you would need to increase the value of the velocity from zero to some finite value. A change is velocity is acceleration, so the value of the acceleration would have to increase from zero to some... | g13742 | [
-0.0031573737505823374,
0.07017513364553452,
0.00356824672780931,
-0.03180958703160286,
0.03331374749541283,
-0.019670767709612846,
0.03607305884361267,
0.05632852017879486,
-0.07515142112970352,
-0.04567703232169151,
-0.08996494859457016,
-0.0037023562472313643,
0.06081153079867363,
0.008... |
<p>I am attempting to estimate the elasto-optic coefficients ($p_{11}$ and $p_{12}$) of $\mathrm{TiO}_2$ and $\mathrm{ZrO}_2$, where $p_{11}$ and $p_{12}$ refer to the elements of a strain-optic tensor for a homogeneous material as given in Hocker (Fiber-optic sensing of pressure and temperature, 1979).</p>
<p>I have ... | g13743 | [
-0.03174138441681862,
-0.045585259795188904,
-0.0011882686521857977,
-0.017810378223657608,
0.042895253747701645,
-0.029038839042186737,
0.01590328849852085,
-0.044321607798337936,
0.02065405808389187,
0.0880470871925354,
-0.004196864552795887,
0.02258492261171341,
0.024291228502988815,
-0... |
<p>What is the sign of the <a href="http://en.wikipedia.org/wiki/Work_%28thermodynamics%29#Formal_definition" rel="nofollow">work</a> done on the system and by the system?</p>
<p>My chemistry course book says, when work is done on the systems, it is taken positive. When work is done by the system, it is taken as negat... | g13744 | [
0.013637956231832504,
-0.01478701364248991,
-0.03282543644309044,
-0.012137911282479763,
0.07526732236146927,
0.005822982173413038,
0.03714986890554428,
0.016385314986109734,
-0.026850085705518723,
-0.02422211691737175,
0.027386432513594627,
-0.01476218830794096,
0.041776612401008606,
0.01... |
<p>I encountered a curious integration identity when I was reading the paper by Pasquale Calabrese and John Cardy on the <a href="http://iopscience.iop.org/1742-5468/2004/06/P06002/fulltext/" rel="nofollow">entanglement entropy of 1+1D quantum field theory</a> (<a href="http://arxiv.org/abs/hep-th/0405152" rel="nofollo... | g13745 | [
0.01228413451462984,
0.004744038917124271,
-0.016705961897969246,
-0.052313514053821564,
0.010790085420012474,
0.00800047256052494,
0.0528448224067688,
-0.003569879336282611,
-0.017361335456371307,
-0.0036216480657458305,
-0.0798838883638382,
-0.009560124948620796,
-0.02967030555009842,
0.... |
<p>We have this formula for centripetal acceleration -
$a = v \frac{d\theta}{dt} = v\omega = \frac{v^2}{r}$</p>
<p>but in case of <em>usual</em> acceleration i know that speed in $t_1 = v_0 + a \cdot (t_1 - t_0)$</p>
<p>but in circular case i don't understande the nature of acceleration, speed is always the same if ... | g13746 | [
0.1104169711470604,
0.014088541269302368,
-0.002268426585942507,
0.011006995104253292,
0.030449969694018364,
-0.019423654302954674,
0.07977189123630524,
0.02107321284711361,
-0.04411280155181885,
0.012793024070560932,
0.007627048995345831,
0.03307740390300751,
-0.0002499626134522259,
-0.02... |
<p>Let´s consider a curved universe that is very small, say 20 square meters and not expanding. </p>
<p>If you stood at the middle of this tiny universe and looked forward, you wouldn´t see any walls, since it is curved. But you would see your back.
If you looked left you would see your right side of your body, and w... | g13747 | [
0.003202544990926981,
0.00285521917976439,
0.02137797139585018,
0.01388526801019907,
-0.0446421317756176,
0.028186485171318054,
-0.008650691248476505,
0.02065911702811718,
0.04957006499171257,
-0.08079694956541061,
-0.004572516772896051,
0.04797809198498726,
0.03568830341100693,
0.01598667... |
<p>Apparently, in Los Alamos scientists handled sub critical masses of plutonium (for example the <a href="http://en.wikipedia.org/wiki/Demon_core" rel="nofollow">demon core</a>) with little or no protection. Richard Feynman and others mentioned that plutonium spheres were warm to the touch, which seems to imply that t... | g13748 | [
-0.014089361764490604,
0.04002669081091881,
0.008027726784348488,
-0.02872937172651291,
0.008873521350324154,
0.0323803685605526,
-0.05331236124038696,
0.01710481569170952,
-0.01603246107697487,
-0.01124912966042757,
0.0023116343654692173,
0.0030628154054284096,
-0.007205502595752478,
-0.0... |
<p>Here's my problem and the work I've done. The time is already past for me to submit the answer, but I want to know where I went wrong and why I was wrong.</p>
<p>The 2-kg box slides down a vertical wall while you push on it at a 45 degree angle from below. Both the box and the wall are wood. What magnitude of for... | g13749 | [
0.0887921079993248,
0.06663324683904648,
-0.008145016618072987,
0.011833187192678452,
0.049397315829992294,
-0.007568583358079195,
0.07869260758161545,
0.011985443532466888,
-0.09185260534286499,
-0.044560614973306656,
-0.03344603255391121,
0.016794485971331596,
-0.02346644550561905,
0.008... |
<p>Almost all optical phenomenon can be explained considering a fluctuating electric field. Is there any optical phenomenon which can't be explained without considering two fluctuating fields, electric and magnetic?</p> | g13750 | [
0.032523564994335175,
0.029171478003263474,
0.0004377492587082088,
0.04205378144979477,
0.05539673939347267,
0.017784245312213898,
0.0222998708486557,
0.03203576058149338,
0.0585218146443367,
-0.014732442796230316,
0.009752757847309113,
0.0131591921672225,
0.030152950435876846,
0.033417563... |
<p><img src="http://i.stack.imgur.com/3pHzS.png" alt="enter image description here"></p>
<p>I understand the definition of the adjoint representation. It uses structure constants as matrix components of generators, but I can't understand meaning of the states $|X_{a}\rangle$. What does "correspond" mean? What is the ... | g13751 | [
-0.0006703998660668731,
-0.007108771707862616,
-0.010097290389239788,
-0.06350241601467133,
0.025390852242708206,
-0.059042852371931076,
0.030144285410642624,
0.07493548095226288,
-0.018594015389680862,
-0.014250378124415874,
-0.0014763911021873355,
0.009552115574479103,
-0.00289760273881256... |
<p>In the minimal-GMSB model, the messenger fields transform under the MSSM gauge group and connect a so-called hidden sector to the visible sector. These meesenger fields (left-handed chiral supermultiplets in this case) break SUSY and introduce the soft terms in the MSSM. I do not understand how to integrate out thes... | g13752 | [
-0.010680494830012321,
0.005335134919732809,
-0.012263156473636627,
-0.020853862166404724,
-0.006123825442045927,
0.07514440268278122,
-0.0035569523461163044,
0.028041014447808266,
0.05697016417980194,
-0.038739971816539764,
-0.05405566468834877,
-0.015453958883881569,
0.0015137047739699483,... |
<p>The question might sound elementary. However, the thing is this. Changing Magnetic field produces a changing electric field. That changing electric field would produce a changing magnetic field. So, is it apt to say that changing magnetic field produces an electric field and a magnetic field? Or should we just stop... | g13753 | [
0.048858512192964554,
0.027624323964118958,
0.01920928619801998,
-0.04007823020219803,
0.05106740817427635,
-0.02825903333723545,
-0.007449503522366285,
-0.018790950998663902,
-0.01783372461795807,
0.004489122424274683,
-0.01488940417766571,
-0.014689557254314423,
0.03858323395252228,
-0.0... |
<p>E-L condition:</p>
<p>$$\frac{d p}{dt}=\frac{\partial L}{\partial q}$$</p>
<p>Where $p=\frac{\partial L}{\partial \dot{q}}$</p>
<p>Are the following steps valid:</p>
<p>$$\frac{\partial q}{dt} dp=\partial L$$</p>
<p>$$\dot{q} \: dp = \partial L$$</p>
<p>$$ \int \dot{q} \: dp = L+C $$</p>
<p>By integration by ... | g13754 | [
0.054632239043712616,
-0.016025537624955177,
-0.008123121224343777,
-0.07545174658298492,
0.04574231430888176,
-0.029420750215649605,
0.0813915953040123,
0.031643010675907135,
-0.036893296986818314,
0.021067503839731216,
-0.051287923008203506,
0.048400282859802246,
0.01763913594186306,
0.0... |
<blockquote>
<p>A uniform rod$(m,l)$ is standing vertically on a horizontal frictionless surface. Gravity is downwards and uniform. I give its upper end a little push and off it goes. I want to find the Normal Force(and all other variables) as a function of time. </p>
</blockquote>
<p>Here's what I do :</p>
<p>$mg-... | g13755 | [
0.07135328650474548,
-0.022581787779927254,
-0.02836596593260765,
-0.052813660353422165,
0.03693770617246628,
-0.010207138955593109,
0.10170052945613861,
0.049363162368535995,
-0.0699993371963501,
0.016402002424001694,
0.01368158869445324,
0.022067023441195488,
-0.01949966512620449,
-0.003... |
<p>Holevo's theorem says that no more than n bits can be stored (and retrieved) in n qubits. Indeed, allowing error can't improve this either -- the probability of retrieving the correct information is no better than that which could be transmitted in the same number of bits and guessing at the rest.</p>
<p>Superdense... | g13756 | [
-0.022190913558006287,
0.09988834708929062,
0.00016234954819083214,
-0.016668343916535378,
-0.011832030490040779,
-0.002695249393582344,
-0.024276187643408775,
-0.009910118766129017,
-0.006454525515437126,
-0.009931061416864395,
-0.05944434925913811,
-0.0032333408016711473,
-0.01146183814853... |
<p>I still can't understand that the phase can be a constant until now.</p>
<p>If the phase is constant, from the </p>
<p>$$y(x,t) = a \times \sin(phase)$$</p>
<p>the shape of wave will be a line parallel to x-axis.But I know that I am wrong,how to explain it?</p> | g13757 | [
0.03610766679048538,
0.03647714853286743,
0.00718541257083416,
-0.014419833198189735,
0.05515880510210991,
-0.012830841355025768,
0.0022950891871005297,
0.04565603286027908,
0.010615435428917408,
-0.03888282924890518,
-0.02937397174537182,
0.0488283708691597,
-0.025437116622924805,
-0.0270... |
<p>This is in reference to slide 19 of this <a href="http://cosmology.lbl.gov/talks/Pajer_13.pdf" rel="nofollow">talk</a></p>
<p>"<em>As always in Effective Field Theory, the theory becomes predictive when there are more observables than parameters</em>" </p>
<ul>
<li><p>Can one explain what this exactly means? May b... | g13758 | [
0.06492859870195389,
0.0490194596350193,
-0.02163139544427395,
-0.018229257315397263,
0.0821380466222763,
0.04795011132955551,
0.04751461744308472,
0.031704630702733994,
0.003413229947909713,
-0.0483657605946064,
-0.03565597906708717,
-0.0030555168632417917,
0.02375130169093609,
-0.0158782... |
<p>Consider a particle with spin that travels through a Stern Gerlach box (SGB), which projects the particle’s spin onto one of the eigenstates in the $z$-direction. The SGB defines separate trajectories for the particles that travel through it depending on their spin.</p>
<p>My Question: At what point is the spin det... | g13759 | [
0.03562214970588684,
0.008692081086337566,
-0.014134855009615421,
0.0038309399969875813,
0.025030914694070816,
-0.0026728231459856033,
0.07864972203969955,
0.05099206790328026,
-0.0161482784897089,
-0.02045007422566414,
-0.06354838609695435,
0.01738259568810463,
0.04039843752980232,
-0.014... |
<p>When drawing ray diagrams for concave mirrors, I was advised to :</p>
<ol>
<li><p>draw a ray that is parallel to the principle axis, the reflected ray will pass through the focus</p></li>
<li><p>Draw a ray through the center (C), the reflected ray will be same as the incident ray but opposite in direction.</p></li>... | g13760 | [
0.016471151262521744,
0.015275395475327969,
0.012340482324361801,
-0.041735123842954636,
0.03790893778204918,
-0.0165498536080122,
0.054277386516332626,
0.013916335068643093,
-0.0018179025501012802,
-0.010012554004788399,
0.023304635658860207,
0.05437023937702179,
0.054037805646657944,
-0.... |
<p><a href="http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=35&category=253&page=show_problem&problem=3491" rel="nofollow">Source</a></p>
<p>Given the coordinates of $n$ 3D joints ($1kg$ each) connected by $m$ rods. Assume rods have zero mass and joints with $z=0$ are fixed to the gr... | g13761 | [
-0.006316169630736113,
-0.00015266015543602407,
-0.004992357455193996,
-0.02677287720143795,
0.04419197514653206,
-0.03158656135201454,
0.015177159570157528,
0.04402117431163788,
-0.06704894453287125,
-0.014577602967619896,
-0.02048533409833908,
-0.015962902456521988,
-0.006884186994284391,
... |
<p>I am asked to calculate the variance of the kinetic energy in the ground state of the harmonic oscillator. That requires $\langle T^2\rangle$. This is the same as $\langle p^4\rangle$. My question is do I have to go about and calculate
$$\langle 0|(a-a^\dagger)^4|0\rangle$$
Or is there a shortcut.</p> | g13762 | [
0.04735949635505676,
0.01668240688741207,
-0.013688994571566582,
-0.034213025122880936,
0.02555651217699051,
-0.03138892725110054,
0.04920044168829918,
0.056363366544246674,
-0.06680861860513687,
0.0073003522120416164,
-0.005487049464136362,
0.021424785256385803,
-0.031115613877773285,
0.0... |
<p>It is given here that the maximum safe speed of a vehicle on a banked road having coefficient of friction $0$, is $V =\sqrt{R g \tan \theta}$, where $\theta$ is the angle of banking. I can't understand how circular motion is possible without friction. </p> | g13763 | [
0.04273097589612007,
0.04098823666572571,
0.01164067629724741,
0.062051787972450256,
0.09972589462995529,
-0.024939309805631638,
0.08386239409446716,
-0.025187397375702858,
-0.023092301562428474,
-0.015203360468149185,
-0.04788406193256378,
-0.038206830620765686,
-0.03164464980363846,
-0.0... |
<p>Noether's theorem relates symmetries to conserved quantities. For a central potential $V \propto \frac{1}{r}$, the Laplace-Runge-Lenz vector is conserved. What is the symmetry associated with the conservation of this vector?</p> | g13764 | [
0.015805352479219437,
-0.01570698246359825,
-0.0026977078523486853,
-0.0316070057451725,
-0.004307036753743887,
0.01734509877860546,
0.0595969595015049,
0.04576355963945389,
-0.030521314591169357,
0.01981709524989128,
-0.059452179819345474,
0.004303588066250086,
-0.06866078823804855,
0.030... |
<p>Why don’t photons interact with the Higgs field and hence remain massless?</p> | g13765 | [
0.06225265562534332,
0.021768862381577492,
0.030162865296006203,
0.02108936384320259,
0.018116099759936333,
0.06448980420827866,
0.008371842093765736,
0.05413734167814255,
-0.004791505169123411,
-0.02880348451435566,
-0.02856886014342308,
-0.01584889180958271,
-0.015340057201683521,
0.0548... |
<p>Do you know cases where chaos theory is actually applied to successfully predict essential results? Maybe some live identification of chaotic regimes, which causes new treatment of situations.</p>
<p>I'd like to consider this from the engineers point of view. By this I mean results that are really essential and not... | g13766 | [
0.04836084321141243,
0.01770724169909954,
0.02402466908097267,
0.026784071698784828,
0.023970115929841995,
-0.04903339594602585,
0.015096701681613922,
0.029087482020258904,
0.059863585978746414,
-0.010609169490635395,
0.05214402824640274,
-0.03414261341094971,
0.05126241594552994,
0.035999... |
<p>What can be a <strong>scientific</strong> solution to the Q-measurement problem (other than many worlds idea)? Can it be somehow verified through experiment?</p> | g13767 | [
0.0009562621708028018,
0.048564471304416656,
-0.003500083228573203,
-0.015136019326746464,
0.020408637821674347,
-0.011340160854160786,
-0.031218377873301506,
-0.014361215755343437,
0.013956457376480103,
-0.027738209813833237,
0.0031539436895400286,
0.0067329322919249535,
0.01160893682390451... |
<p>Consider this <a href="http://www.youtube.com/watch?v=MYNJITf9brg" rel="nofollow">youtube video of a guy lifting a car.</a> (skip to 2:15).</p>
<p>I checked, and these cars (PT Cruiser) weigh $1417\:\rm{kg}$. <strong>What would the equation be to estimate how much weight he is actually deadlifting?</strong> The lev... | g13768 | [
0.004002382978796959,
0.048636242747306824,
-0.01639961265027523,
-0.039448440074920654,
0.00011507219460327178,
-0.013865613378584385,
0.06058160215616226,
0.013423091731965542,
-0.03524298220872879,
0.03420336917042732,
-0.04193362593650818,
-0.06195588409900665,
0.012297072447836399,
-0... |
<p>I am facing the following question. It is well known that power laws arise in many situations in nature. They arise even in thats physical systems that are completely deterministic (e.g. sand piles). But power law is a probability distribution function and can be thought as generated from a stochastic variable. What... | g13769 | [
0.08085393905639648,
0.017160095274448395,
0.0012929923832416534,
-0.0028023049235343933,
0.05198957771062851,
0.05150866508483887,
-0.03838707506656647,
-0.007900255732238293,
-0.05772016569972038,
-0.03680901974439621,
-0.019752822816371918,
-0.02556547522544861,
0.04686247184872627,
0.0... |
<p>Why is oil a poor conductor of heat? Does it help in insulation?</p> | g13770 | [
0.019350050017237663,
0.023706693202257156,
-0.005469805561006069,
-0.02624444290995598,
0.00251202704384923,
-0.025843435898423195,
-0.020334186032414436,
0.035517387092113495,
-0.04476509988307953,
-0.019443577155470848,
-0.041495952755212784,
-0.02927260659635067,
-0.019871335476636887,
... |
<p>I was reading this answer by madame anna v: </p>
<blockquote>
<p>You are right, the planetary model of the atom does not make sense when one considers the electromagnetic forces involved. The electron in an orbit is accelerating continuously and would thus radiate away its energy and fall into the nucleus.</p>
... | g430 | [
0.023960039019584656,
0.04613460972905159,
0.02074413374066353,
0.017048304900527,
0.09779619425535202,
0.06100374087691307,
-0.036389462649822235,
0.003007550025358796,
-0.023274479433894157,
-0.032356441020965576,
0.054398998618125916,
0.04110505431890488,
0.036889996379613876,
-0.019043... |
<p>I understand that the inter-galactic space is expanding but galaxies themselves are not. What is happening to the space within a galaxy? Is it fixed by the gravity of the galaxy or is it expanding and moving out around it?</p>
<p>Using the coins on a balloon analogy, is the balloon surface under the coins (galaxies... | g56 | [
0.006078088190406561,
0.06820079684257507,
0.010870475322008133,
-0.012128732167184353,
0.0015800927067175508,
0.034053705632686615,
-0.0039711594581604,
-0.04291791096329689,
-0.03808640316128731,
-0.0776786357164383,
0.015375679358839989,
0.026681071147322655,
-0.011738304048776627,
-0.0... |
<p>I am reading <a href="http://rads.stackoverflow.com/amzn/click/3540736174" rel="nofollow"><em>Free Energy Calculations: Theory and Applications in Chemistry and Biology</em> by Chipot and Pohorille</a>. At the beginning of the text (page 19, for example), the authors define the Helmholtz free energy $A$ and changes... | g13771 | [
0.04731791466474533,
-0.0071830786764621735,
-0.02472708187997341,
-0.016652323305606842,
0.010744191706180573,
-0.001477460958994925,
0.036126572638750076,
0.031477198004722595,
-0.036987077444791794,
-0.027335455641150475,
-0.08813582360744476,
0.02571575529873371,
0.043750736862421036,
... |
<p>A string with a fixed frequency vibrator at one end forms a standing wave with 4 antinodes when under tension T1. When the tension is slowly increased, the standing wave disappears until tension T2 is reached with no resonances occurring between the two tensions. How many antinodes are there in this new standing wav... | g13772 | [
0.05809013172984123,
0.0097210593521595,
0.00138916727155447,
-0.008510025218129158,
0.06710430979728699,
-0.012072720564901829,
-0.010471773333847523,
0.0015294356271624565,
-0.029121482744812965,
-0.03316060081124306,
-0.12659411132335663,
-0.023898549377918243,
-0.04306159168481827,
-0.... |
<p><em>I am wondering can someone help to solve second part which extends first part;</em></p>
<p>The power radiated by the sun is ${3.9*10^{26}}_{watt}$. The earth orbits the sun in a nearly circular orbit of radius $1.5 *10^{11}m$. The earth’s axis of rotation is tilted by $27^o$ relative to the plane of the orbit ,... | g13773 | [
0.02965894341468811,
0.017856812104582787,
-0.04440128058195114,
-0.033562298864126205,
-0.02206539176404476,
0.007911888882517815,
0.04187377169728279,
-0.01561267301440239,
0.006820953916758299,
0.016609860584139824,
0.03702981770038605,
0.0692320466041565,
-0.03565426915884018,
0.006922... |
<p>I have not been able to find any information about this on the Internet. I am a middle-schooler, 14, who self-studies physics, and I know up to and including ODEs, and some of the calculus of variations, enough so that I can take a variation of the action. However, I have absolutely zero budget, and no ability to ge... | g13774 | [
-0.030545061454176903,
-0.003172624623402953,
-0.020346317440271378,
-0.0011500394903123379,
0.05242694169282913,
0.035321950912475586,
-0.018649183213710785,
0.04629580304026604,
-0.027923686429858208,
-0.007438203319907188,
-0.05752259120345116,
-0.013018769212067127,
0.021396595984697342,... |
<p>I was sitting down yesterday and saw my phone vibrate on a side, and it moved about a centimetre per vibration.
I wondered why it moves, and thought perhaps that the side it was on had a slight slope, because it tended to move in the same direction every time.
So I then though, what if the side was perfectly flat?... | g13775 | [
0.04739686846733093,
-0.007134116720408201,
0.0006782291457056999,
0.0004709010536316782,
0.06994981318712234,
0.040893346071243286,
0.018868837505578995,
-0.0052663967944681644,
-0.004669311922043562,
-0.03385530784726143,
-0.037298981100320816,
0.007626939099282026,
0.04136047884821892,
... |
<p>There are many things with different textures that appear white – salt, beer foam, paper, shaving cream, snow, talcum powder, white paint, etc. The most common answer is all of the frequencies must be reflected in order for us to perceive white, which I already know. There must be more underlining details why such a... | g13776 | [
0.04744984954595566,
0.07399316877126694,
-0.0007060414645820856,
-0.03636877238750458,
0.08748769760131836,
0.011158978566527367,
0.03207550570368767,
0.026140568777918816,
0.00315676792524755,
-0.02545822039246559,
0.03878772631287575,
0.018561171367764473,
0.05821321904659271,
0.0566504... |
<p>I know how an air gap behaves: for lower voltages the resistance is extremely high, until spark voltage is achieved, at which point resistance rapidly drops, creating electric arc. Now, how does that behave if we remove air?</p>
<p>Let's assume a part of electronic circuit that is a vacuum pipe with two electrodes ... | g13777 | [
0.035456523299217224,
0.0027859818655997515,
-0.03321578726172447,
0.03430047631263733,
0.01123217586427927,
0.034597430378198624,
0.00782062578946352,
0.03359875828027725,
-0.0058308811858296394,
-0.011824198067188263,
-0.0026374030858278275,
0.05734049901366234,
-0.013859758153557777,
-0... |
<p>...speaking of Perseid meteor showers...How close would a Perseid meteorite have to be in order to be heard by the human ear? Is it even possible to hear a Perseid meteorite? If they come close enough, would we hear "ka-boom!", or would it sizzle, or do they <em>always</em> burn up before we hear them?</p> | g13778 | [
0.028188854455947876,
0.0037033422850072384,
0.012554554268717766,
-0.06988178938627243,
-0.04473663493990898,
0.0529777929186821,
-0.08253531903028488,
0.03477725759148598,
0.015610985457897186,
-0.007795247714966536,
-0.007679739501327276,
0.036132026463747025,
0.029040217399597168,
-0.0... |
<p>The problem:</p>
<blockquote>
<p>In a car crash, a passenger with a mass of 82kg is not wearing a
seatbelt. The car is travelling at 45km per hour. What impulse must
the car's airbag provide in order to stop the passenger's motion?</p>
<p>Explain why hitting an airbag will cause less injury than if a
p... | g13779 | [
0.01915649138391018,
0.044620782136917114,
0.008844523690640926,
0.016191542148590088,
0.044253237545490265,
0.020689675584435463,
0.03389472886919975,
0.003490216564387083,
-0.10455584526062012,
-0.07677829265594482,
0.02835393324494362,
-0.03573911637067795,
0.02616126276552677,
-0.01647... |
<p>I'm currently in the process of writing a 2.5D application that should display the perceived size of an object. For example, When I have a ball that has a diameter of 1 meter, how big would it appear if the ball would be 5 meters away from me? I know that there is angular diameter, but how can I translate the angle ... | g13780 | [
-0.0011377099435776472,
-0.047870490700006485,
-0.008882596157491207,
-0.10780028253793716,
-0.042926300317049026,
-0.01696062460541725,
0.024058479815721512,
-0.008544420823454857,
-0.0368744395673275,
-0.004519515670835972,
-0.01893165335059166,
0.008661533705890179,
0.12023798376321793,
... |
<p>Why the color motion picture film, or a color photographic slide, appears as black?
The film appears black but when the light from the projector lamp hit it then you can see all the colors.</p> | g13781 | [
0.07826147973537445,
0.014406617730855942,
0.018006134778261185,
0.009989961050450802,
0.04051290825009346,
-0.042163386940956116,
-0.014900474809110165,
0.08061660826206207,
-0.009049997664988041,
0.02372581511735916,
0.044229812920093536,
0.0540568046271801,
0.04865635186433792,
0.036911... |
<p>In a transformer assumed to be transformer, power in the primary is equal to power in the secondary. So in a sense, the power in the secondary is 'fixed'. Output voltage in the secondary is also fixed by the turns ratio and the voltage in the primary. Then, The current tapped from the secondary coil should also be f... | g13782 | [
0.012655920349061489,
-0.0714842826128006,
0.0013841360341757536,
-0.0571245513856411,
0.03387182578444481,
-0.024810373783111572,
0.032268647104501724,
0.015165457502007484,
-0.04382298141717911,
0.012771748937666416,
-0.06278135627508163,
0.030716679990291595,
-0.03954307734966278,
-0.00... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://physics.stackexchange.com/questions/27641/entanglement-in-time">Entanglement in time</a> </p>
</blockquote>
<p>I heard that there is an experiment that uses quantum entanglement to try to send messages back to the past. I am having a hard ... | g431 | [
-0.03120935522019863,
0.034388840198516846,
0.01509490329772234,
-0.040335919708013535,
0.05240194872021675,
-0.004246929660439491,
-0.008563525974750519,
0.019243933260440826,
-0.01328399870544672,
0.032222162932157516,
-0.0216397512704134,
0.04599791765213013,
0.003765504341572523,
0.009... |
<p>First of all sorry for my English - it is not my native language.</p>
<p>During my engineering studies at the university the thermodynamics professor told us that the "second law of thermodynamics is not true for a low number of molecules".</p>
<p>At that time scientists were already talking about micro technologi... | g13783 | [
0.05905582010746002,
0.03548956289887428,
0.021554997190833092,
0.007194632664322853,
0.034308791160583496,
-0.016007425263524055,
-0.012101255357265472,
0.01892230659723282,
-0.05217219889163971,
-0.023087235167622566,
-0.006150334142148495,
0.03519768267869949,
-0.014275801368057728,
-0.... |
<p>Today's liquid crystal shutter glasses, when in the "transparent" state, exhibit only 40% light transmission.</p>
<p>They work using two polarizer layers, one which is liquid crystal and goes {vertical <-> horizontal} under electronic control, and the other which is static horizontal. Thus, even when the polariz... | g13784 | [
-0.0022438617888838053,
0.030843596905469894,
0.02241038717329502,
0.04521169140934944,
-0.016600504517555237,
-0.03803125396370888,
0.030085096135735512,
0.011455516330897808,
0.04139689728617668,
0.004492846317589283,
0.018832804635167122,
0.031132444739341736,
-0.004837641492486,
0.0070... |
<p>I have studied for a couple of months now a mathematical model of the energy of a configuration of immiscible fluids situated in a fixed container such that the fluids fill the container. In other terms, I considered a partition of the container into $2,3,...n$ sets. I will present the $3$ fluid case here.</p>
<p>... | g13785 | [
0.040950216352939606,
-0.0005365419783629477,
0.005592650268226862,
-0.023520154878497124,
0.00838769506663084,
0.0029258723370730877,
0.029941758140921593,
-0.020110400393605232,
-0.10909241437911987,
0.0013947978150099516,
0.008875121362507343,
-0.029381662607192993,
-0.04191888868808746,
... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.