question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Let's say we have one black hole that formed through the collapse of hydrogen gas and another that formed through the collapse of anti-hydrogen gas. What happens when they collide? Do they (1) coalesce into a single black hole or do they (2) "annihilate" into radiation?</p>
<p>One would expect (1) to be the case if... | g793 | [
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<p>How it could be proven that a non-trivial theory cannot be both asymptotically free and IR free (g=0 both in the UV and IR with some interpolating function in between)? This is of course contrary to the behaviour of both QED and QCD in which we have monotonically RG flow.</p> | g10373 | [
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<p>I was reading <a href="http://www.edge.org/3rd_culture/hillis/hillis_p2.html" rel="nofollow">http://www.edge.org/3rd_culture/hillis/hillis_p2.html</a> and it says that a charged battery weighs more than a dead one or a rotating object weighs more than a stationary one (i.e. mass containing energy weighs more than ma... | g10374 | [
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<p>I was asked to calculate the drag force on a cone with velocity 10 m/s , everything was okay until i needed to calculate the cross sectional area , the radius of the base was 0.5 m , radius of the top 0.0005 m , given that the cone falls top first, which one should i use ?
should i get some kind of an average?</p> | g10375 | [
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<p>There is traditionally a bit of confusion between missing transverse energy, and missing transverse momentum. I've seen both used interchangably, and sometimes even things like "$\not E_T = -|\sum \vec p_T|$".</p>
<p>Just to clarify before my question, if both quantities are used, then missing transverse momentum u... | g10376 | [
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<p>How is it possible to calculate torque that is applied on a domain due to the magnetization force[H]?</p> | g10377 | [
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<p>I am in the middle of a vehicle tracking project where I have to calculate the distance traveled by the vehicle in a given amount of time. </p>
<p>Data I am getting:</p>
<pre><code>Speed : 30.2 km/hr 12.7 km/hr 15 km/hr 21.8 km/hr
Time : 11:00:00 11:00:22 11:00:45 11:01:10
</code></pre>
<p>T... | g10378 | [
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<p>I am reading the book <a href="http://en.wikipedia.org/wiki/The_Evolution_of_Physics" rel="nofollow">The Evolution of Physics</a>. I have a doubt in the topic "The field as representation". In this topic authors give the example of gravitational force represented as a field. In the following image the small circle r... | g333 | [
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<p>Consider two non-interacting distinguished particles in one-dimensional infinity square potential.
Suppose the particles have the same mass $m$, and the potential is zero in the region $\frac{a}{2}>x>-\frac{a}{2}$. In the coordinate of $x_1,x_2$, the Schrodinger eq.
$$-\frac{\hbar^2}{2m}\partial^2_{x_1}\psi(x... | g10379 | [
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<p>I hear very often among my peers and seniors that just as how $\hbar\rightarrow0$ takes me to classical mechanics from quantum mechanics, $k_B\rightarrow0$ will take me to classical thermodynamics from statistical mechanics.</p>
<p>As nice as this sounds, my gut feeling and intuition tells me this is not the right ... | g10380 | [
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<p>I'm trying to make some order of magnitude estimates of heat transfer in stars - to better understand 1) why conduction is said to be negligible (for non-degenerate matter) and 2) when convection happens and is dominant.</p>
<p>For thermal conduction, I have the expression that the flux of energy over a surface</p>... | g10381 | [
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<p>I've seen some conflicted answers to this question in texts and on the web, in the case of a dipole, for example. </p>
<p>Do magnetic fields do work directly, or is it their induced electric fields that do work?</p> | g10382 | [
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<p>Assume I have a inverse cone which holds 200ml water. I am going to cut the tip of the cone to create a small hole. How to calculate the maximum radius of the hole that the water will still stay in the container ?</p> | g10383 | [
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<p>I was trying to understand Witten's proof of the Positive Energy Theorem in General Relativity by reading the <a href="http://projecteuclid.org/DPubS?service=UI&version=1.0&verb=Display&handle=euclid.cmp/1103919981" rel="nofollow">original argument given by Witten</a>. I am comfortable with the overall a... | g10384 | [
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<p>Is nature symmetric with respect to presence of particles? Do we have an antiparticle for every particle thought of? Are there any proven examples where we don't have an antiparticle? And what about antiparticle of a photon (we know it can also behave as a particle)? </p> | g10385 | [
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<p>I didn't get the basic difference in between the different types of microscopy. for example there are several different microscopy techniques are available such as Bright field, Dark field, Confocal, STED, electron microscopy etc. Is only the illumination system varies in between different techniques or are there an... | g10386 | [
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<p>Everyone knows how the surface of a spinning bucket of water would look like on earth - parabolic. But what if we turned off gravity (for instance by doing the experiment in a freely falling lift)? Would the surface be still parabolic? I'll explain my confusion in more detail.</p>
<p>The velocity of the spinning bu... | g10387 | [
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<p>If I remember correctly, I heard some people saying that the transistors on CPUs today are so small, that they have to use quantum physics to make CPUs. Is that correct?</p> | g10388 | [
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<p>I want to solve some exercises involving U-tubes, like</p>
<p>You pour two non-mixing fluids with densities that go like 1:2 into a U-tube. The fluid is 5cm higher in one arm than in the other. Where is the seperating line?</p>
<p>Unfortunately, I don't know any of the formulas one can use for such exercises, all ... | g10389 | [
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<p>I am asked to show $[L^2,L_i] = 0 $, but with the definition :</p>
<p>$L^2 \equiv L_i L^i$</p>
<p>I tried this:</p>
<p>$[L_i L^i,L_i] = L_i [L^i,L_i] + [L_i,L_i]L^i$</p>
<p>We know that : $[L_i,L_i]$ = 0 , so we have,</p>
<p>$[L_i L^i,L_i] = L_i [L^i,L_i]$.</p>
<p>So I could not understand this term with upper... | g10390 | [
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<p>The question is simple. When we join the two broken surfaces, what is it that keeps the surfaces from connecting with each other, while earlier they were attached to each other? Also, would the two sides join again if I hold them together for an infinite amount of time?</p> | g10391 | [
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<p>The <em>standard Lorentz transformation</em> or <em>boost</em> with velocity $u$ is given by
$$\left(\begin{matrix} ct \\ x \\ y \\ z \end{matrix}\right) = \left(\begin{matrix}
\gamma & \gamma u/c & 0 & 0 \\
\gamma u/c & \gamma & 0 & 0 \\
0 & 0 & 1 & 0 \\
0 & 0 & 0 & ... | g10392 | [
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<p>I did an experiment in university in which I determined how far $\alpha$-particles emmited from an $Am^{241}$ source penetrate into air. I want to compare my result to literature values but... I cant find any on google! Can somebody point me to a source for this?</p>
<p>Cheers in advance!</p> | g10393 | [
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<p>In lab, my TA charged a large circular parallel plate capacitor to some voltage. She then disconnected the power supply and used a electrometer to read the voltage (about 10V). She then pulled the plates apart and to my surprise, I saw that the voltage increased with distance. Her explanation was that the work she ... | g10394 | [
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<p>I have two PCBs (printed circuit board), and they are glued by adhesives, as show in the pictures. And the location of the adhesives are indicated on the picture (please notice that NO adhesive is applied between the PCB boards).</p>
<p><strong>50N</strong> force is applied on the upper PCB (Z direction). I use adh... | g10395 | [
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<p>I read on page 5 of Matthew Schwartz' book QFT & the SM that if you heat a box with monochromatic light, then (later) all the frequencies will get excited. The author says that particles have to be created and destroyed to accomplish this. This must show the need for QFT. </p>
<p>I'm just wondering if I will ev... | g10396 | [
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<p>I have a computer simulation from which I get a sample of values of some microscopic quantity $X$, i.e. $\{ x_1,\ldots,x_N \}$. I'm interested in estimating the expected value of $X$, i.e. $E[ X]\approx\frac{1}{N}\sum x_i$, and the variance associated with this <strong>estimate</strong>. </p>
<p>Now, do I understan... | g10397 | [
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<p>In case of Dirac neutrino there is no $1/2$ factor in the mass Lagrangian but for Majorana type neutrino there is a half factor in the mass Lagrangian.</p> | g10398 | [
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<p>In my thermodynamics course (and in other places on the internet) it is asserted that the Zeroth Law of Thermodynamics can be used to define the concept of temperature. One statement of the Zeroth Law I have seen states that the relation <em>thermal equilibrium</em> on two closed systems brought into diathermal con... | g10399 | [
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<p>I am new to differential geometry, so far it seems to me that computing the Riemann tensor tends to be a rather tedious task, I wanted to know whether there are some tricks that I am missing. </p>
<p>In particular I'm looking at the exercises on page 287 of <a href="http://rads.stackoverflow.com/amzn/click/07503060... | g10400 | [
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<p>A lot of text books mention that one of the reasons that classical mechanics failed to explain atomic and subatomic processes is that electrons which accelerate should release energy in the form of electromagnetic radiation, which would lower the atoms overall energy level, but this does not happen. One place where ... | g10401 | [
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<p>Back in my undergrad I had a course on classical electrodynamics where the fields had values in the space of tempered distributions. In this way one could correctly treat self-interaction and effectively solve the differential equations involved in the distribution sense.</p>
<p>Unfortunately the few notes that I h... | g10402 | [
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-0.020743058994412422,
-0.046990472823381424,
0.053690552711486816,
-0.012562048621475697,
0.035554997622966766,
0.017293209210038185,
-0.01807442493736744,
-0.0031493587885051966,
-0.037151139229536057,
0.011309467256069183,
0.035037823021411896,
... |
<blockquote>
<p><em>A cylinder of mass $m$ and radius $R$, is rolled on surface with coefficient of kinetic friction $\mu_{k}$ about the axis passing through the center and parallel to the surface, with initial angular velocity $\omega_{0}$; the work done by frictional force from start until it begins to roll w/o sli... | g10403 | [
0.01483062468469143,
0.03077191859483719,
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0.00795372948050499,
0.05345960333943367,
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0.14365547895431519,
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0.024962587282061577,
0.07556355744600296,
0.0284071... |
<p>It's possible to perform type-II frequency doubling of unpolarized light in suitable nonlinear crystals. But for a single beam of linearly polarized input light, is it still possible to do type-II doubling? I vaguely remember reading that it can be done if the crystal is oriented at a 45-degree angle to the polariza... | g10404 | [
-0.005636594723910093,
0.03001028299331665,
0.03890059515833855,
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0.04766257852315903,
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... |
<p>I'm reading the Wikipedia page for the <a href="http://en.wikipedia.org/wiki/Dirac_equation" rel="nofollow">Dirac equation</a>:</p>
<blockquote>
<p>$$\rho=\phi^*\phi$$</p>
<p><em>and this density is convected according to the probability current
vector</em></p>
<p>$$J = -\frac{i\hbar}{2m}(\phi^*\nabla... | g10405 | [
0.0716802328824997,
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0.024796955287456512,
0.0843539... |
<p><strong>What exactly is the difference between internal resistance and resistance?</strong></p>
<hr>
<p>This came up in the context of a homework problem I have been given:</p>
<blockquote>
<p>The circuit shown in the figure contains two batteries, each with an
emf and an internal resistance, and two resistor... | g10406 | [
0.022672543302178383,
-0.046121563762426376,
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0.024275343865156174,
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0.0409846268594265,
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-... |
<p>As a warning, I come from an "applied math" background with next to no knowledge of physics. That said, here's my question:</p>
<p>I'm looking at the possibility of using <a href="http://en.wikipedia.org/wiki/Probability_amplitude">probability amplitude functions</a> to represent probability distributions on surfa... | g10407 | [
0.01983254961669445,
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0.051963359117507935,
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0.0033053888473659754,
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0.07214748859405518,
... |
<p>How can it be shown without using the little group formalism?</p>
<p>Let's have the Wigner's classification for the irreducible represetation of the Poincare group. For the massless case the eigenvalues of two Casimir operators of the group, the squares of Pauli-Lubanski operator and momentum operator, $\hat {W}_{\... | g10408 | [
0.05611871927976608,
-0.03640161082148552,
-0.015716344118118286,
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0.014697136357426643,
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0.06385283172130585,
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0.03134315088391304,
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0.05... |
<p>Drift velocity (explained to me as how fast the electrons are moving) is <em>really</em> slow. My book says the electrons move at around 10 mm/ s.</p>
<p>If electrons move so slowly how do circuits work so fast? If you make a basic circuit with just a light bulb, the bulb lights up almost immediately after you conn... | g10409 | [
0.023071853443980217,
0.06248747929930687,
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0.03786566108465195,
0.002897433703765273,
0.0174... |
<p>This is a question based on concepts of two dimensional motion . Here's how the question is:</p>
<blockquote>
<p>A plank A is floating in air, gravity has no effect on it (See its coordinates in the figure attached). At $t=0$ plank starts moving along the x-axis with an acceleration of $1.5 \ \mathrm{m/s^2}$. At ... | g10410 | [
0.10243849456310272,
0.061654407531023026,
0.008981101214885712,
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0.0070593... |
<p>Suppose a current flows in a straight cylindrical wire so that an electric field $\textbf{E}$ is maintained in the wire.
Will there be an electric field just outside the wire..?</p> | g10411 | [
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<p>A question has recently come up that goes beyond my knowledge of special relativity. Suppose a pilot has his foot on the gas pedal of a rocket ship and keeps it applied to achieve a constant acceleration, and he has a magical engine that can maintain the thrust needed to accomplish such acceleration even as the veh... | g37 | [
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<p>Dominoes, when placed upright, remain that way. Sometimes, even if you tip them a little bit, they will go back to their upright position.</p>
<p>However, if you tip them too far, they will fall over.</p>
<p>After trying this with many different sized/shaped dominoes and some textbooks, I've noticed that this ang... | g10412 | [
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<p>Two spaceships approach an observer from an equal distance and from an opposite direction with an equal speed $v$ in the observer's intertial reference frame $O$.
The speed of a spaceship in the intertial reference frame of the other spaceship $S$ is $0.8c$, what is the speed of one of the spaceships in $O$?</p>
<p... | g10413 | [
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0... |
<p>This is not a homework question, just a question I have developed to get a better conceptual understanding of the results of the Schrödinger equation.</p>
<p>If I had a 3D spherical container or radius R, containing 2 particles of opposite charge, say a proton and an electron, what does the solution to the resultin... | g10414 | [
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0.028420208021998405,
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0.04305405542254448,
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0.0033257061149924994,
0.03925677016377449,
... |
<p>(This is a simple question, with likely a rather involved answer.)</p>
<p><strong>What are the primary obstacles to solve the many-body problem in quantum mechanics?</strong> </p>
<p>Specifically, if we have a Hamiltonian for a number of interdependent particles, why is solving for the time-independent wavefunctio... | g633 | [
0.012627235613763332,
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0.005433246493339539,
0.0495... |
<p>What about the size of the door (space) and how long has it to be opened (time)?</p>
<p>I think Maxwell's demon would have a problem with space, if the door is too wide (more than one particle size), then direct interaction between the two part is possible and would lead to lose isolation restriction, like there we... | g10415 | [
0.001209244946949184,
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0... |
<p>How could I find the acceleration of a body knowing only that its position and velocity satisfy $v^2 = f(x)$, where $f(x)$ is a known function of $x$ (position)?</p> | g10416 | [
0.060111161321401596,
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<p>To a first approximation, the earth currently radiates out as low frequency thermal radiation the same amount of energy as it absorbs as high frequency solar radiation. (This ignores energy generated within the earth, which is also radiated away. But that amount is constant and is not relevant to my question. It als... | g10417 | [
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<p>Particle colliders like the LHC or the Tevatron use a complex accelerator chain to have particles at a given energy before being accelerated.</p>
<p>For example:</p>
<ul>
<li><a href="http://public.web.cern.ch/public/en/Research/AccelComplex-en.html" rel="nofollow">The CERN accelerator complex to inject in the LHC... | g10418 | [
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0.0153... |
<p>My copy of Feynman's "Six Not-So-Easy Pieces" has an interesting introduction by Roger Penrose. In that introduction (copyright 1997 according to the copyright page), Penrose complains that Feynman's "simplified account of the Einstein field equation of general relativity did need a qualification that he did not qui... | g994 | [
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0.052171189337968826,
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0.01705913059413433,
... |
<p>I've been reading papers about nanomechanical oscillators, and the concept of quality factor often pops up. I understand to some extent about <a href="http://en.wikipedia.org/wiki/Q_factor" rel="nofollow">Q factor</a> in classical sense, but since nanomechanic oscillators are often treated quantumly, what does Q fac... | g10419 | [
0.0699508935213089,
0.045808590948581696,
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0.0003993067657575011,
0.045454151928424835,
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0.017721176147460938,
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... |
<p>So I am working with a 2-ray (actually it's 8 ray now, but that's merely an extension) wireless signal propagation model. The equation of the component of interest:</p>
<p>$
P = \vert{1-\Gamma\exp\left(j2\pi/\lambda*(\sqrt{(d^2+(2h^2))} - d)\right)}\vert^2
$</p>
<p>This produces a sinusoid with progressively incre... | g10420 | [
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0.00... |
<p><strong>Fact:</strong> We all know that during the day <strong>concrete</strong> absorbs heat and <strong>releases it during the night</strong>, making urban areas hotter than rural areas.</p>
<p>I observed that after sunset the ambient temperature is going down until late at night when it actually starts to feel... | g10421 | [
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0.005037244874984026,
0.0293752271682024,
0.0208... |
<p>In some literatures, the Hamilton's principle for conservative systems is introduced by this equation:
$$\delta \int_{t_1}^{t_2}(T-V) ~\mathrm{d}t~=~0$$</p>
<p>In some others, this principle is introduces as follow:</p>
<p>$$\int_{t_1}^{t_2}\delta(T-V) ~\mathrm{d}t~=~0$$</p>
<p>What is the difference between two ... | g10422 | [
0.04817190021276474,
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0.02151874452829361,
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0.019647859036922455,
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-0.0... |
<p>There's a caveat, which is often ignored, to the "easy" equation for parallel plate capacitors C = epsilon * A / d, namely that d must be much smaller than the dimensions of the parallel plate.</p>
<p>Is there an equation that works for large d? I tried finding one and could not. (These two papers talk about fringi... | g10423 | [
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0.06910078972578049,
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0.04044370353221893,
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0.0... |
<p>What is the equation of motion for a single scalar field, which has a Lagrangian density in which the potential explicitly depends on time? For example: $$U(\phi,t)=\frac{1}{2}\phi^2 - \frac{1}{3} e^{t/T}\phi^3 + \frac{1}{8}\phi^4$$ where $T$ is a constant.</p> | g10424 | [
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0.027... |
<p>Can windmills allow us to consume (and, eventually, over-consume) the wind as a natural resource somewhat in the same manner that we are over-consuming many other natural resources?</p> | g10425 | [
0.03873509541153908,
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0.026... |
<p>I mean, what is happening at a microscopic level to cause this behavior? Here's what I got from Wikipedia:</p>
<ol>
<li>On <a href="http://en.wikipedia.org/w/index.php?title=Reflection_%28physics%29&oldid=438178514#Reflection_of_light">Reflection (physics)#Reflection of light</a> it says that "<em>solving Maxwe... | g10426 | [
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0.013433323241770267,
0.027984177693724632,
0.08001764863729477,
0.02... |
<p>In order to calculate the cross-section of an interaction process the following formula is often used for first approximations:</p>
<p>$$
\sigma = \frac {2\pi} {\hbar\,v_i} \left| M_{fi}\right|^2\varrho\left(E_f\right)\,V
$$
$$
M_{fi} = \langle\psi_f|H_{int}|\psi_i\rangle
$$</p>
<p>Very often plane waves are a... | g10427 | [
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0.049... |
<p>What constitutes protons? When I see pictures, I can't understand. Protons are made of quarks, but some say that they are made of 99% empty space. Also, in this illustration from Wikipedia, what's between the quarks?</p>
<p><img src="http://i.stack.imgur.com/CcjvK.png" alt="image"></p> | g10428 | [
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<p>In dimensional regularization an arbitrary mass parameter $\mu$ must be introduced in going to $4-\epsilon$ dimensions. I am trying to understand to what extent this parameter can be eliminated from physical observables.</p>
<p>Since $\mu$ is arbitrary, physical quantities such as pole masses and scattering amplitu... | g10429 | [
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<p>I do not know much about physics but I know that according to Newtons third law of motion when we walk we are pushing the ground down but the ground is pushing us up. What force is making the ground push us up. How come gravity doesn't pull us and the ground down.</p> | g268 | [
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0.08132511377334595,
0.00820686761289835,
0.016301389783620834,
0.03173963725566864,
0.09553420543670654,
0.021587466821074486,
0.04069744050502777,
-0.04688646271824837,
-0.02137434110045433,
0.01469437312334776,
-0.07919913530349731,
-0.018970996141433716,
-0.054999... |
<p>I'm reading about the cavity radiation in the context of blackbody theory. I'm asking myself: WHY do we describe this radiation by the use of standing waves? Why can't they be not-standing, maybe reflecting along some strange paths inside the cavity itself?</p> | g10430 | [
0.004517390392720699,
0.049312103539705276,
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0.05055500566959381,
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0.0362250953912735,
0.02610429935157299,
0.018263474... |
<p>We just started learning about pressure in our school, and i am a bit confused. I tried to google extensively, but i didn't really find much.</p>
<p>In mechanics, so far in our school we've been taught about Newton's laws of motion and some related stuff, and suddenly we started learning about pressure. I asked thi... | g10431 | [
0.07470576465129852,
0.010736426338553429,
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0.08624137938022614,
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0.006319145206362009,
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0.02301984652876854,
-0.0... |
<p>Do ideal gases at zero Kelvin have potential energy?</p> | g553 | [
0.042673468589782715,
-0.012369022704660892,
0.005945316981524229,
-0.007131998892873526,
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0.024098532274365425,
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0.014611616730690002,
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-0.07084240019321442,
... |
<p>It is known, that Reissner-Nordstrom black hole is thermodynamically unstable [1].</p>
<ul>
<li>Does it mean, that there is no Reissner-Nordstrom black hole in physical world?</li>
<li>Does it mean, that there may be phase transition?</li>
<li>Does it mean, that it can be stable for enough long time?</li>
</ul>
<p... | g10432 | [
0.006781852338463068,
0.003233141265809536,
0.012461714446544647,
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0.024945978075265884,
0.046281274408102036,
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0.012222856283187866,
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0.0060823033563792706,
0.015242502093315125,
0.04757767543196678,
-0.0025016467552632093,
-0.... |
<p>It looks like usual criteria (positivity of Hessian; what geometrically means a cancave of entropy) is no useful, becouse entropy is not additive and not extensive for black hole. Then what is the right criteria?</p> | g10433 | [
0.024135688319802284,
0.04366369545459747,
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0.019037390127778053,
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0.07068546116352081,
0.00018964936316478997,
0.062997005879879,
0.02138... |
<p>Recently IBM created world’s <a href="http://www.youtube.com/watch?list=PLaFe0BJiho2pbiULC7W4UpxFGArH7oD7i&v=oSCX78-8-q0&feature=player_embedded" rel="nofollow">smallest ever animation</a> on an atomic scale video. Researchers made the animation using a scanning tunnelling microscope to move thousands of car... | g10434 | [
-0.001911818515509367,
0.07889813184738159,
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0.005651017650961876,
0.02844749391078949,
0.05724504217505455,
0.04916509613394737,
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0.007579166442155838,
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0.009417966939508915,
0.04973148554563522,
0.02730... |
<p>In the text, it introduces a practical model to investigate a transmission line (like BNC cable), it considers the transmission line has resistive $R$, inductance $L$, conductance $G$ and capacitance $C$. The model is illustrated as follow</p>
<p><img src="http://i.stack.imgur.com/Iaxe3.jpg" alt="enter image descri... | g10435 | [
-0.017712578177452087,
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0.003950633108615875,
0.06362320482730865,
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0.042656779289245605,
0.001851334236562252,
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0.029098916798830032,
0.008898083120584488,
... |
<p>I am trying to write a matlab function that calculates the coefficient of thermal expansion of water from a given temperature. From what I understand the thermal expansion coefficient is calculated as the degree of expansion divided by the change in temperature, expressing the tendency of a fluid to change in volume... | g10436 | [
0.056679144501686096,
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0.025688089430332184,
0.012110165320336819,
0.00172530603595078,
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0.022197768092155457,
0.02439509704709053,
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-0.015766218304634094,
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0.02045886218547821,
0.086918905377388,
0.0230... |
<p>I have been studying causality (specifically why there is no such thing as a simultaneous instant of time across all observers) recently and I keep hearing references to the Andromeda paradox. Can anyone tell me what it is and how it is resolved?</p>
<p>I've tried reading what <a href="http://en.wikipedia.org/wiki/... | g10437 | [
0.10335516929626465,
0.003056684508919716,
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0.04971214383840561,
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0.08506207913160324,
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0.009633911773562431,
0.060457389801740646,
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0.042946744710206985,
0.0... |
<p>I am curious as to whether or not parallax barrier could be used to create the illusion that a screen is bigger than its physical dimensions. I assume this would only work in one dimension (width?). But could I potentially see a single screen as if it were a dual monitor setup? Right-eye sees the left screen, left e... | g10438 | [
-0.014635228551924229,
0.06312639266252518,
0.00899108313024044,
0.034344423562288284,
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0.012984017841517925,
0.00823746994137764,
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0.03418600559234619,
-0.028488995507359505,
0.0829799473285675,
0.04279888793826103,
0.012730619870126247,
0.001629... |
<p>Suppose we start out by having two entangled electrons. We separate them by some distance and we put one electron inside a thin loop of wire connected to an extremely sensitive voltage measuring device at lab 1 and the second electron at lab 2. At this point, no measurement is made. Both electron's spin's are undete... | g10439 | [
-0.04511392116546631,
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0.05722494795918465,
0.00048258781316690147,
0.025820190086960793,
0.031070703640580177,
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0.027875274419784546,
-0.04881996661424637,
0.05001041293144226,
-0.007403832860291004,
0.... |
<p>I am facing problem in calculating the value of given <a href="http://en.wikipedia.org/wiki/Clebsch%E2%80%93Gordan_coefficients" rel="nofollow">Clebsch–Gordan coefficients</a> representing the coupled angular momenta of two-particle system. For example</p>
<p>$$\begin{pmatrix}2 & 1 & 2 \\ 1 & -1 & 0... | g10440 | [
0.058835554867982864,
-0.004453612491488457,
-0.01062894705682993,
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0.08787011355161667,
-0.037905629724264145,
0.0432242751121521,
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0.05343347787857056,
0.011604269035160542,
0.017904045060276985,
0.00452059879899025,
-0.014... |
<p>Hold two cards (say credit cards) edge to edge, anything from a very slight
touch to about 1/3 mm separation, in front of any ordinary light
source. When I do this I see several
fine dark parallel lines in the gap. What are those? Are they discussed in
elementary texts?</p> | g10441 | [
0.041059818118810654,
0.024169964715838432,
-0.030324967578053474,
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0.058299191296100616,
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0.0172966867685318,
-0.035554416477680206,
0.01309294905513525,
0.0383661612868309,
0.017414573580026627,
-0.00... |
<p>I saw someone do some tricks with a toy helicopter where he would turn it upside down for a while and it would still stay in the air. I thought it should have crash or at least not fly for very long in that position, but I was wrong. Is it possible for the helicopter to have change its propellers turing direction so... | g10442 | [
0.02422959916293621,
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0.008765957318246365,
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0.02593338117003441,
0.0... |
<p>My question is related to <a href="http://physics.stackexchange.com/questions/91113/the-geodesic-line-on-poincare-half-plane/91117#91117">this question</a>. There are three or four other questions on Killing Vector Fields here, however none of them that I have seen address my question.</p>
<p>$\\$</p>
<p>I've been... | g10443 | [
0.044789791107177734,
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0.006697487086057663,
0.09254666417837143,
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0.07587055116891861,
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-0.0017206084448844194,
-0.0014562655705958605,
-0.009376906789839268,
0.02693367190659046,... |
<p>I think we are all very well familiarized with the classical voltmeter. Classical voltmeter has two conducting wires that bring two potentials into the box. In the box we have <strong>well controlled conditions</strong>, in which potential difference (voltage) starts current, and current through the galvanometer d... | g10444 | [
0.010514602065086365,
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0.01851227693259716,
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0.05672440305352211,
0.032372210174798965,
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0.018130559474229813,
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0.006328323390334845,
-0.06352154165506363,
0.03454703092575073,
-0.059335093945264816,
0.... |
<p>I have been trying to understand the formula</p>
<p>$$v_f^{2}=v_i^{2}+2V(V(1-\cos\beta)+v_i(\cos(\alpha-\beta)-\cos\alpha))$$</p>
<p>as it relates to Fig. 2 on page 5 of this exposition:</p>
<p><a href="http://maths.dur.ac.uk/~dma0rcj/Psling/sling.pdf" rel="nofollow">http://maths.dur.ac.uk/~dma0rcj/Psling/sling.p... | g10445 | [
-0.004962690640240908,
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0.007865375839173794,
0.05538081377744675,
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0.1037343367934227,
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0.00290759583003819,
-0.025934677571058273,
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0.04942845553159714,
0.018752239644527435,
-0.0... |
<p>So recently, looking at high energy particles through the lens of General and Special Relativity has peaked my interest. One thing I was considering, using the electron as the first example, is as follows:</p>
<p>If gravity is the result of mass (stress-energy tensor), and as particles approach the speed of light, ... | g112 | [
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0.0019593387842178345,
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0.008526050485670567,
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0.053150638937950134,
0.0569765605032444,
-0.0... |
<p>Why do objects always 'tend' to move in straight lines? How come, everytime I see a curved path that an object takes, I can always say that the object tends to move in a straight line over 'small' distances, but as you take into account the curvature of the path, a force acting on the particle appears. I mean, I can... | g637 | [
0.03446575254201889,
0.030764572322368622,
0.0037492041010409594,
0.030170133337378502,
0.08966059982776642,
0.015501167625188828,
0.006411589216440916,
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0.04934147000312805,
0... |
<p>I came across the following statements in 't Hooft's black holes notes, but not being able to justify them.</p>
<p>The metric in the Rindler coordinates $x=\tilde{x}, y=\tilde{y}, z= \rho \cosh{\tau}, t= \rho \sinh{\tau}$ is
$$ds^2 = -\rho^2 dt^2 + d\rho^2 + d\tilde{x}^2+d\tilde{y}^2$$</p>
<ol>
<li>Gravitational ... | g10446 | [
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0.035690415650606155,
0.03307025879621506,
0.0076751322485506535,
0.033150605857372284,
... |
<p>As I work a problem set, I'm being asked to calculate the latent heat associated with a particular phase transition of $NH_3$ (solid -> liquid, liquid -> gas, solid -> gas).</p>
<p>I'm being told to perform the calculation at the triple point (P, T), which I've already calculated based upon two phase specific formu... | g10447 | [
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0.03324492648243904,
0.04316979646682739,
-0... |
<p>Alright, I've been interested in the <a href="https://en.wikipedia.org/wiki/Thermoelectric_effect#Seebeck_effect" rel="nofollow">Seebeck effect</a> lately, so I've been trying to learn it. From what I understand, this is measured with the Seebeck Coefficient, which gives you the $\mu\textrm{V}$ (Millionth of a volt)... | g10448 | [
0.04157057777047157,
-0.0026739835739135742,
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0.001245124381966889,
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0.0408644936978817,
0.027030209079384804,
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0.042666539549827576,
-0.021114801988005638,
0.053996097296476364,
-0.013323495164513588,
... |
<p>I am reading a paper:</p>
<p><a href="http://arxiv.org/ftp/arxiv/papers/1305/1305.2445.pdf" rel="nofollow">http://arxiv.org/ftp/arxiv/papers/1305/1305.2445.pdf</a></p>
<p>On p. 22, the following Hamiltonian is given:</p>
<p>$$ H = \mu_B g \mathbf{B} \cdot \mathbf{S} + D(S_Z^2+\frac{1}{3}S(S+1)) + E(S_X^2 - S_Y^2)... | g10449 | [
0.005023886449635029,
0.03849579766392708,
-0.02237316407263279,
-0.0005443088593892753,
0.04360216483473778,
0.030656149610877037,
0.08036983758211136,
0.06509816646575928,
0.03147442266345024,
0.03157268837094307,
-0.06954549252986908,
0.05403975397348404,
0.01780558191239834,
-0.0473178... |
<p>For example, if they were driving at top speed through a long tunnel, could they transition to and stay on the ceiling?</p> | g10450 | [
-0.03662276268005371,
0.060686610639095306,
0.02036682702600956,
0.0346553698182106,
0.012652481906116009,
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0.011935397982597351,
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-0.03404649347066879,
... |
<ol>
<li><p>Were the forces of nature combined in one unifying force at the time of the Big Bang?</p></li>
<li><p>By which symmetry is this unification governed?</p></li>
<li><p>Are there any evidence for such unification of forces?</p></li>
<li><p>Has ever been published Theory or experiment in this issue? (Even origi... | g10451 | [
0.018758296966552734,
0.03640706464648247,
0.005632529966533184,
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0.01312918122857809,
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0.0026102911215275526,
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0.008188790641725063,
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-0.013432634063065052,
-0... |
<p>What experiments have challenged or supported <a href="http://en.wikipedia.org/wiki/AdS/QCD" rel="nofollow">AdS/QCD</a>, AdS/CMT, etc? What experiments should we look forward to do this?</p> | g10452 | [
0.022255968302488327,
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0.014223330654203892,
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-0.06434259563684464,
0.07450901716947556,
0.0662749707698822,
0.0010429396061226726,
0.04450... |
<p>I want to understand the transmission coefficient and construct a time-independent Schrodinger equation where
$$
V(x)=\left\{
\begin{array}{c c}
\delta(x), & |x| < 1 \\
+ \infty, & |x| \geq 1. \\
\end{array}
\right.
$$
$$
\Psi(x,0)=\left\{
\begin{array}{c c}
1, & 0< x < 1 \\... | g10453 | [
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0.056289296597242355,
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0.044800128787755966,
0.03112596645951271,
-0.01616101898252964,
0.050481293350458145,
-0.03130101040005684,
0.05475609377026558,
-0.04193941503763199,
-0.00... |
<p>Typically one writes simultaneous eigenstates of the angular momentum operators $J_3$ and $J^2$ as $|j,m\rangle$, where </p>
<p>$$J^2|j,m\rangle = \hbar^2 j(j+1)|j,m\rangle$$
$$J_3 |j,m\rangle = \hbar m|j,m\rangle$$</p>
<p>There seems to be an implicit assumption that the eigenvalues of these operators are non-deg... | g10454 | [
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0.032252028584480286,
-0.023157749325037003,
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-0.027928221970796585,
0... |
<p>Can we argue based on Landauer's principle that if one bit information is changed inside a blackbody, the total radiated energy should be at least or in order of kTln2? If it is so, can we also argue that this energy should be distributed over all the modes of the cavity? Furthermore, can it also be argued that this... | g10455 | [
-0.002803353825584054,
0.008376030251383781,
0.004889012314379215,
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0.015578887425363064,
-0.016891829669475555,
0.01232269685715437,
-0.019167518243193626,
... |
<p>If one sees a meteor, is there any way to get even a rough approximation of its height, entry angle, size, or other characteristic <em>without triangulation</em> from another position? </p>
<p>If it appeared as a point source and got uniformly brighter, you'd know to take a step aside. And if it appeared on one hor... | g10456 | [
-0.0068688783794641495,
-0.012119418941438198,
0.0035235616378486156,
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0.010258668102324009,
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0.00802219845354557,
0.001965979812666774,
-0.00637210626155138,
-0.0035106255672872066,
0.004885233473032713,
0.0695960745215416,
... |
<p>I heard that when the wavelength and obstacle are similar in size, the scattering is the greatest. Is this true?</p> | g10457 | [
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<p>In Witten's paper <a href="http://projecteuclid.org/DPubS?service=UI&version=1.0&verb=Display&handle=euclid.cmp/1104161738" rel="nofollow">Topological Quantum Field Theory</a>, about formula (3.2), the property $<\{Q,\mathcal{O}\}>=0$ depends on the assertion that $Z_{\varepsilon}(\mathcal{O})= \in... | g10458 | [
0.04070156067609787,
0.040547214448451996,
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0.008121863938868046,
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0.060744643211364746,
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... |
<p>Can we argue based on Landauer's principle that if one bit information is changed inside a blackbody, the total radiated energy should be at least or in order of $kTln2$? If it is so, can we also argue that this energy should be distributed over all the modes of the cavity? Furthermore, can it also be argued that th... | g10459 | [
-0.0022669583559036255,
0.011016725562512875,
0.01411427091807127,
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0.02174966223537922,
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0.0131913423538208,
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0.020285319536924362,
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-... |
<p>I am trying to find a supplement to appendix of Cushman & Bates' book on Global aspects of Classical Integrable Systems, that is less terse and explains mechanics with Lie groups (with dual of Lie algebra) to prove Symplectic reduction theorem (on locally free proper G-action), Arnold-Liouville Theorem (on compl... | g10460 | [
0.05942067503929138,
0.0008747585234232247,
0.01952371373772621,
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0.038520555943250656,
-0.01550504844635725,
0.0027100422885268927,
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0.03... |
<p>For an examples class on thermodynamics, I would like to fit <a href="http://en.wikipedia.org/wiki/Van_der_Waals_equation" rel="nofollow">Van der Waals law</a> on data of real gasses, say $CO_2, H_2O_2, CH_4$. </p>
<p>I want to set out measurements of pressure and volume at constant temperature in a P-V diagram, a... | g10461 | [
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0.014631452970206738,
0.023764749988913536,
-0.05587003007531166,
0.005654220003634691,
-... |
<p>In a question, its given that a plank is resting on 2 rollers like: </p>
<p><img src="http://i.stack.imgur.com/afMB1.png" alt="enter image description here"></p>
<p>Then the explanation, as part of computing the forces, for the direction of friction on the rollers look like: </p>
<p><img src="http://i.stack.imgur... | g10462 | [
0.061009764671325684,
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0.... |
<p>The <a href="http://scienceworld.wolfram.com/physics/CanonicalMomentum.html" rel="nofollow">canonical momentum</a> is always used to add an EM field to the Schrödinger/Pauli/Dirac equations. Why does one not use the <a href="http://en.wikipedia.org/wiki/Gauge_covariant_derivative#Gauge_theory" rel="nofollow">gauge c... | g10463 | [
0.04137379676103592,
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0.03885898366570473,
-0.04215652123093605,
0.002573310863226652,
-0.008385... |
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