question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Lets say we have 1 gram of plasma (Argon) at 1 million kelvin confined in a vacuum with electromagnets. If we keep the magnets on but shut down the device that heated the plasma, how long will it take for it to cool off?</p> | g15747 | [
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<p>Since light beams carry momentum, why would a person holding a flashlight not feel a recoil similar to that of a rifle being fired?</p> | g483 | [
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<p>In discussing Doppler effect, we use the word "apparent frequency". Does it mean that the frequency of the sound is still that of the source and it is some physiological phenomenon in the listener's ears that give rise to the Doppler effect?</p> | g15748 | [
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<p>Why both <a href="http://en.wikipedia.org/wiki/Dirac_fermion" rel="nofollow">Dirac</a> mass and <a href="http://en.wikipedia.org/wiki/Majorana_fermion" rel="nofollow">Majorana</a> mass terms are needed to explain the mass of a neutrino?</p> | g15749 | [
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<p>I was always wondering about the acausal nature of solutions obtained by Fourier transforms in the case of inhomogeneous equations. The solution usually revolves around the integration of the transform of the inhomegeneous term - and that transform necessarily depends on all future values of that term - so is it rea... | g15750 | [
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<p>I just watched "Man of Steel", and I'm wondering if my logic is correct.</p>
<p>Let's assume Superman is 80 kg. The energy required to take off from the rest to reach the speed of sound in air (if I neglect the drag) is:</p>
<p>$E_k = 0.5mv^2$ = $0.5\cdot80\cdot340^2$ = $4\times10^6 \ J$.</p>
<p>Also add the pote... | g15751 | [
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<p>For example:</p>
<p>$Xe^{+}+e^{-} \rightarrow Xe + \mbox{energy}$</p>
<p>Assuming that the electron has a kinetic energy $\neq 0$.</p>
<p>Is the released energy a photon or heat?</p> | g15752 | [
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<p>When comparing mechanical resonance of an object (for example string) in air and in water, does the resonance frequency changes? My guess is that it does change because the surrounding medium will slow it down. Thank you.</p> | g15753 | [
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<p>Electrons have spin 1/2, and as they are charged, they also have an associated magnetic moment, which can be measured by an electron beam splitting up in an inhomogeneous magnetic field or through the interaction of the electrons's magnetic moment with an external magnetic field in spectroscopic measurements. </p>
... | g15754 | [
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<p>Displacement correlation functions in question are within harmonic approximation and are derived for example in: A. Maradudin, Dynamical properties of solids 1, 1 (1974). Maradudin says about the displacement time correlation functions that: "The physical interpretation of these correlation functions is simple only ... | g15755 | [
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<p>What are governing equations (or/and variational principles) for evolution of a simply connected body of water in vacuum?</p>
<p>Initial state - for time $t=0$ we have a bounded simply connected set $\Omega$ containing water, for simplicity - macroscopic velocity is zero and macroscopic temperature is constant.</p> | g15756 | [
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<p>I know Lorentz force don't do any work. but I want to know whether any type of magnetic field do a work or not.</p> | g484 | [
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<p>If I understand correctly, it has something to do with autocorrelation function, but can someone give me a definition or exact explanation?</p>
<p>In case of scattering, if you wish to analyze pattern with Fourier transform, you can only do so within deep Fresnel region. Apparently (according to the text I've been ... | g15757 | [
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<p>I can never get my head around the violations of $P-$, $CP-$, $CPT-$ violations and their friends. Since the single term "<em>symmetry</em>" is so overused in physics and one has for example to watch out and differentiate between diffeomorphism covariance and symmetries of a Lagrangian, which might give Noether char... | g15758 | [
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<p>in a homework sheet studying bond-percolation on the Bethe lattice, a function $g(r)$ is introduced as "the probability of finding two nodes separated by a distance $r$ on the same cluster". </p>
<p>Now just to see if I get this definition right, for the simple one-dimensional case (Bethe lattice with coordination ... | g15759 | [
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<p>Similar to <a href="http://physics.stackexchange.com/questions/193/best-books-for-mathematical-background/2592#2592">this</a> reference, are there more such references / works [including textbooks] available in the literature?
(A list would be greatly welcomed and appreciated.)</p>
<p>With great appreciation. </p> | g390 | [
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<p>I read some while ago that, currently, eleven different formulations of quantum mechanics exist. Is this correct / accurate? If yes, can someone provide a pointer(s) (i.e. link(s)) to the various formulations?</p> | g15760 | [
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<p>I always hear about matter converting to 'energy' - fusion, fission.</p>
<p>When does it go the other way around? What conditions lead to it? Are there reproducible experiments on this topic?</p> | g15761 | [
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<p>It is very crucial that I ask whether it ``could'' and not whether it does. I do not mean to be the least controversial.</p>
<p>To my surprise, having read ``Physics for Future Presidents'' by Richard Muller last year, I've come across a sentence of the sort (I'm paraphrasing): cell phone radiation is way too weak ... | g15762 | [
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<p>Via a packet-switched network, like the internet, data is sent as packets (bits) wirelessly via radio waves with Wi-Fi, or 802.11g, etc.</p>
<p>What my question is is this:</p>
<p>Radio waves are light; light has no mass. How can data be sent via radio waves if radio waves have no mass, hence, can't carry data?</p... | g15763 | [
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<p>How many planetoids have been discovered that are, say, 50% the size of Pluto or larger? Where are they?</p>
<p>Incidentally, what <em>is</em> the difference between a planet, a planetoid, and an asteroid?</p> | g15764 | [
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<p>How is information defined from a thermodynamics point of view ? I came across some definitions using the concept of free energy of a system. If I have information stored in a finite volume of space what does it mean for the free energy and entropy of the space ?</p> | g15765 | [
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<p>It's stated probably in all textbooks on many-body functional integrals that operators that satisfy
$$
\hat{a}^\dagger \hat{a} + \hat{a} \hat{a}^\dagger = 1
$$
must have eigenvalues that satisfy
$$
\psi \psi' + \psi' \psi = 0 ,
$$
where $\psi$ and $\psi'$ are two eigenvalues of the $\hat{a}$ operator:
$$
\begin{arra... | g15766 | [
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<p>This question concerns the article <a href="http://amasci.com/elect/mcoils.html" rel="nofollow">Right Angle Circuitry</a>.</p>
<p>Having passed a grad E&M course, I feel like this should make perfect sense to me and I should be able to answer all the questions it raises. Sadly that is not yet the case.</p>
<p>... | g15767 | [
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<p>I am reading the first paper in Schwinger's QED anthology, where he discusses his action principle. In this, he writes down states that are simultaneous eigenkets of the field operators at all points of a space-like surface $\sigma $, $\lvert\Phi', \sigma\rangle$, which obey $\Phi(x)|\Phi', \sigma\rangle = \Phi'(x)|... | g15768 | [
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<p>I am trying to find the geodesics on the surface defined by $M:=\{(x,y,z)\in\mathbb{R}^3|x^2 + y^2 = f(z)\}$, for $f:\mathbb{R}\rightarrow \mathbb{R}_+$.
I have parametrized the surface by
$$
\vec{r} = \sqrt{f(z)}\cos\theta\hat{i} + \sqrt{f(z)}\sin \theta \hat{j} + z\hat{k}
$$
and calculated the metric components to... | g15769 | [
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<p>Considering that the reason typically given for launching spacecraft from sea-level as opposed to mountains is that the limiting factor is <em>velocity</em>, not <em>altitude</em>, then why isn't the <a href="http://en.wikipedia.org/wiki/Pegasus_%28rocket%29" rel="nofollow">Pegasus</a> rocket launched from a superso... | g15770 | [
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<p>sorry for this very naive (layman) question. </p>
<p>What is space?
It seems to be every where in the equations of physics (as some sort of postulate or hidden hypothesis). We also have a direct experience of it. But is it "real"? The fact that we experience it doesn't mean that it exists by itself. For example, wh... | g15771 | [
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<p>In Quantum Mechanics the square of the wave function is compared to a probability density. Is there no similar relation to waves in the sense that something meaningful can be ascribed to the real part of the wave function, in the way that the real part of an EM wave is the actually measurable thing?</p> | g15772 | [
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<p>I've seen in this article that potential energy is defined like this:
$U=-\int _{\text{ref}}^r\overset{\rightharpoonup }{F}\cdot d\overset{\rightharpoonup }{r}$.</p>
<p>However I've seen in other text books that potential energy is:
$\text{$\Delta $U}$.</p>
<p>What is the difference?</p>
<p>Why is "Delta" used so... | g15773 | [
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<p><a href="http://physics.stackexchange.com/questions/80773/the-example-of-relativity-of-simultaneity-given-by-einstein/80776#80776">This answer</a> to a recent question related to <a href="http://archive.org/details/relativitythespe00einsuoft#chapters.8.and.9" rel="nofollow">Einstein's thought-experimental definition... | g15774 | [
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<p>When deriving the impact-free boltzmann equation ( $\frac{\partial f}{\partial t} + \vec{v} \cdot\frac{\partial f}{\partial \vec{x}} + \vec{a} \cdot \frac{\partial f}{\partial \vec{v}} = 0$) I have a question about the notion. Basically we are looking at the change in particles in a given volume $V$ which is given b... | g15775 | [
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0.0016324437456205487,
0.06656928360462189,
0.03398342430591583,
0.08742161095142365,
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0.0756840854883194,
0.09498342871665955,
0.0133... |
<p>Consider free, real scalar field theory in $d=1+3$ dimensions: $H = \frac{1}{2} \partial_\mu \phi \partial^\mu \phi + \frac{1}{2} m^2 \phi^2$. The Hilbert space of this theory is known; it is just the vacuum plus each of the $n$-particle Hilbert spaces spanned by plane waves (something like $\mathbb{C} \times L^2(\... | g15776 | [
0.014550363644957542,
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0.012198306620121002,
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0.002831208286806941,
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0... |
<p>1) I understand light dispersion. But, I wonder what happens if I used a lens to focus it into a small point. Would it be a white point (would it reverse dispersion) or would I have a multicolored point?</p>
<p>2) I know how do light filters work. Like red filter only lets red light through. But are there any filte... | g15777 | [
-0.013205506838858128,
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<p>How can the multiplication of spinor representations (of $SO(8)$) $8_+ \otimes 8_-$ be decomposed into $8_v \oplus 56_v$? Where can I read more about the decomposition rule of different representations?</p>
<p>Thank you.</p> | g15778 | [
0.007030474487692118,
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<blockquote>
<p>A potential function is given by $V(r)=\frac{Ae^{-\lambda r}}{r}$ Find charge density and hence charge.</p>
</blockquote>
<p>I first took the gradient of potential to get $\vec{E}(r)=\frac{Ae^{-\lambda r}}{r}[\lambda+\frac{1}{r}] \hat{r}$</p>
<p>Now using Gauss's law $\nabla \cdot \vec{E}=\frac{\rho... | g15779 | [
-0.008432403206825256,
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0.060771822929382324,
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0.024363359436392784,
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<p>I'm happy to accept and use conservation of energy when I'm solving problems at Uni, but I'm curious about it to. For all of my adult life, and most of my childhood I've been told this law must hold true, but not what it is based on.</p>
<p><strong>On what basis do we trust Conservation of Energy?</strong></p> | g15780 | [
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0.0138... |
<p>Light (or any radiation as a matter of fact) is an electromagnetic wave so why doesn't it have a electric charge associated with it?
As far as I know only static or flowing electric chargers can produce electric fields and if it does have a charge why doesn't light (i.e. a photon) respond to an electric or magnetic... | g485 | [
0.04967496916651726,
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<p>This is a basic question, but it does not seem to be well defined anywhere. Generally, two terms are mixed somewhat randomly: <a href="http://www.google.com/search?as_epq=transmission+probability" rel="nofollow">transmission PROBABILITY</a> and <a href="http://en.wikipedia.org/wiki/Transmission_coefficient" rel="nof... | g15781 | [
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<p>If an unbound electron (or indeed any charged particle) is moving through free space, is there a probability that it can spontaneously change energy by emitting a photon, or does this require the presence of an external potential $A_4$. </p>
<p>The important point is that the process is spontaneous, like jumping en... | g15782 | [
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0.019303377717733383,
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0.05736074596643448,
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0.022... |
<p>I think it would be neat if one could configure one's eyesight parameters (<a href="http://en.wikipedia.org/wiki/Astigmatism_%28eye%29" rel="nofollow">astigmatism</a> and <a href="http://en.wikipedia.org/wiki/Myopia" rel="nofollow">myopia</a> in my case), viewing distance, and perhaps age into a special display driv... | g486 | [
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0.02019605226814747,
0.08893090486526489,
0.002530287718400359,
0.0798988789319992,
0.00801... |
<p>How to take differential of Quantum mean value over hermitian operator (mean or expectation value)?
$$d\langle \hat A\rangle$$
remark:
or time evolution of mean value over operator
$$\frac {d\langle \hat A\rangle}{dt}$$</p>
<blockquote>
<p>what is the problem here?
ok let me talk a little more special in three ... | g15783 | [
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0.021201085299253464,
0.010522911325097084,
0.0240... |
<blockquote>
<p>Assume a car has hit a wall in a right angled collision and the front bumper has been displaced 9 cm. The resulting impact is 25g. Also, it is evident by skid marks that the car braked for 5m with an acceleration of 1.5m/s^2. What is the impact velocity in this collision?</p>
</blockquote>
<p>Here's ... | g15784 | [
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0.013939007185399532,
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0.021... |
<p>In QM we require that the state that describes the system, an atom say, be symmetric or antisymmetric under permuting the identical particles.</p>
<p>What identical particles are we talking about here, all electrons in an atom? or only electrons that belong to the same energy level (degenerate electrons)?</p> | g15785 | [
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<p>Superconducting wire can host a low current magnetic field. I do not know if it supports a corresponding electrical field.</p>
<p>Can a superconducting wire that sustains a current accelerate a DC motor? Where is the resistance in a superconducting homopolar motor?</p>
<p>Please explain if I am way off of target. ... | g15786 | [
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<p>Mathematically speaking, is there any essential difference between <a href="http://en.wikipedia.org/wiki/Initial_value_problem" rel="nofollow">initial value problems</a> and <a href="http://en.wikipedia.org/wiki/Boundary_value_problem" rel="nofollow">boundary value problems</a>?</p>
<p>The specification of the valu... | g15787 | [
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<p>In MTW book there is one exercise in which there was proposed to discuss linearized tensor gravity, which is represented as
$$
g_{\mu \nu} = \eta_{\mu \nu} + h_{\mu \nu}, \quad \eta_{\mu \nu} = diag(1, -1, -1, -1).
$$
I have the question about lagrangian of fields in this case: in the book it is written in a form
$$... | g15788 | [
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<p>I'm studying property of sound wave and I was wondering what is difference between two waves (one is original and one is 180 flip phase of original) ?</p>
<p>Amplitude and frequency remains same and also wavelength is same, so are they same?? I could not detect any difference from hearing two sounds. If different w... | g15789 | [
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<p>If I understand correctly, negative pressure usually means relative pressure: the difference between inside and outside.</p>
<p>If outside is normal (1 bar, 15 psi, 100 kPa etc), how low can the (relative) pressure inside be? Can it be -20 psi / -1.5 bar / -150 kPa?</p>
<p>Absolute pressure can't be negative, righ... | g15790 | [
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<p>I've come to this sentence and I don't understand the term <em>Nyquist edge</em>. </p>
<blockquote>
<p>Because observing in the FM band is not feasible, a sampling frequency of 200 MHz has been chosen for most of the receiver modes. This sampling results in a Nyquist edge almost at the center of the FM band.</p>
... | g15791 | [
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<p>I am a mathematician working on a seismic imaging problem, and am currently (attempting to) read some geophysics papers (<a href="http://www.researchgate.net/publication/233898393_Determination_of_the_friction_law_parameters_of_the_Mw_6.7_Michilla_earthquake_in_northern_Chile_by_dynamic_inversion">this one</a> (Ruiz... | g15792 | [
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<blockquote>
<p>Before answering, please see <a href="http://meta.physics.stackexchange.com/a/4698"><strong>our policy</strong></a> on
resource recommendation questions. Please try to give substantial answers that detail the
<strong>style, content, and prerequisites</strong> of the book or paper (or other resourc... | g282 | [
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<p>Let us assume that we have the ferromagnetic surface where all atoms have the same direction of spins. And we can interact with the single atom in such lattice.
Is it possible to measure the direction of the atom's spin, by means of coherent light?</p> | g15793 | [
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<blockquote>
<ul>
<li>A system of two equal and opposite charges separated by a certain distance is called an electric dipole. </li>
<li>Electric dipole moment ($p$) is defined as the product of either charge ($q$) and the length ($2a$)of the electric dipole. </li>
<li>Magnitude of electric field ($E$) due to... | g15794 | [
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<ul>
<li><p>I wanted to know if there is a theorem that in writing a Lagrangian if one missed out a term which preserves the (Lie?) symmetry of the other terms and is also marginal then that will necessarily be generated by RG flow to the IR.</p>
<p>(..like a massless scalar field Lagrangian in 3+1 will generate the m... | g15795 | [
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<p>I hear that unitary evolution and information conservation must imply that information about information content that defines the initial state of matter used to create a black hole can be inferred from hawking radiation of the black hole. </p>
<p>Now if I measure the hawking radiation that comes out from a black h... | g15796 | [
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<p>Pardon me if this is a stupid question but my physics courses are from a long long time ago and I was a teenager back then. ;)</p>
<p>Electricity in a wire generates electromagnetism, right?
Would it be possible to capture this EM field and use it as a power source or store in an accumulator?</p>
<p>Would that inc... | g15797 | [
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<p>Intuitively I feel that if you compactified open bosonic strings on a product of $n$ circles such that each radius is fine-tuned to the self-dual point then the CFT of these $n$ world-sheet fields would "see" a Kac-Moody algebra for some rank "n" Lie group.</p>
<ul>
<li><p>True? If yes then what is a good proof of ... | g15798 | [
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<p>I'm studying how the Renormalization Group treatment of the simple Gaussian model,
$$\beta H = \int d^d r \left[ \frac{t}{2} m^2(r) + \frac{K}{2}|\nabla m|^2 - hm(r)\right]$$</p>
<p>In momentum space, the Hamiltonian reads
$$\beta H = \frac{1}{(2\pi)^d} \int d^d q \left[\frac{t + q^2 K}{2} |m(q)|^2\right] - hm(0)$... | g15799 | [
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<p>What exactly is a resonance state? </p>
<p>My understanding so far is that a resonant state appears as a large spike in the DOS of a material due to an adsorbed impurity or vacancy in the lattice and that they act as quasilocalized states, but I can't seem to find a source which describes exactly what one is.</p>
... | g15800 | [
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-0.0400... |
<p>When I was much younger, I remember being fascinated by the thought of an Island of Stability at very high atomic numbers. However, I have not heard much on this and I was wondering</p>
<ul>
<li><p>Did this idea ever have any meaningful support in the scientific community, or was it a fringe theory?</p></li>
<li><... | g15801 | [
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<p>Does a finite wave necessarily have to be non-monochromatic in reality, or is that implication just a result of the mathematical analysis? I always wonder at these sort of things that come out of a strictly mathematical analysis. </p> | g15802 | [
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-0.05014842376112938,
0.083299... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://physics.stackexchange.com/questions/16048/what-are-quarks-made-of">What are quarks made of?</a> </p>
</blockquote>
<p>Are quarks and leptons actually fundamental, or are they made up of even more fundamental particles? And is it true that... | g324 | [
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0... |
<p>I was searching for introductions to current mathematics derived from / related to gauge theories in physics.</p>
<p>Can someone suggest some good references? </p>
<p>E.g.</p>
<p><em><a href="http://rads.stackoverflow.com/amzn/click/1848829388" rel="nofollow">Topics in Physical Mathematics</a> by K. Marathe</em>... | g390 | [
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0.026027953252196312,
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<p>This air plane just caught my eye. Two contrails apparently are flowing backward, slightly off-centered and then ultimately converge, giving the overall shape of a very narrow rhomboid parallelogram, with one diagonal being on the order of about four plane-width's.</p>
<p>Please explain what I am seeing here as det... | g15803 | [
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0.043980054557323456,
-0.014764050021767616,
0.050056587904691696,
... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://physics.stackexchange.com/questions/11321/confused-about-the-role-of-mass">Confused about the role of mass</a> </p>
</blockquote>
<p>I know that two different masses fall at the same rate in the same gravitational field because the greater... | g85 | [
0.05453679710626602,
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0.022171104326844215,
-0.0023519... |
<blockquote>
<p><em>Suppose we have a particle with mass $m$ and energy $E$ in a gravitational field $V(z)=-mgz$. How can I find the wave function $\psi(z)$?</em> </p>
</blockquote>
<p>It should have an integral form on $dp$. Any help would be appreciated.</p>
<p><strong>What I've tried</strong></p>
<p>One way to ... | g15804 | [
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0.028106248006224632,
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0... |
<p>I'm studying for a physics test, but I think I don't really understand Galilean invariance. In my textbook there is an example in which they prove that if you consider 2 frames S and S' in standard configuration that the second law of Newton is Galilean invariant by proving that if $x' = x - Vt$ than $F_x = F'_x$, s... | g15805 | [
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<p>I've been reading derivations of the thermodynamic temperature scale. I'm assuming these are using Kelvin's method. I follow the math and the conclusion of the argument, but I don't understand how it defines a temperature scale.</p>
<p>The derivation goes like this:</p>
<p>We have two thermal reservoirs, one at a ... | g15806 | [
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<p>This is my first time taking a physics course (I'm a mathematics major), so I'm encountering a lot of new things, which I'm kind of expected to know. In particular, how to work with Bosons.</p>
<p>I've got the following question to work out;</p>
<blockquote>
<p>Let $F_2$ denote the Fock subspace of all 2-boson s... | g15807 | [
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<p>We know that for a real gas we can write a virial expansion in powers of $p$:</p>
<p>$$pV=Nk_{B}T+B(T)p+\cdots$$</p>
<p>It results that the van der Waals equation:</p>
<p>$$\left[p+a\left(\frac{N}{V}\right)^{2}\right]\left(V-Nb\right)=Nk_{B}T$$</p>
<p>can be rewritten like</p>
<p>$$pV=Nk_{B}T+\frac{N}{N_{A}}\le... | g15808 | [
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... |
<p>The $SU(2)$ flux defined in the context of <a href="http://prb.aps.org/abstract/PRB/v65/i16/e165113" rel="nofollow">PSG</a> is as follows:</p>
<p>Consider the mean-field Hamiltonian $H_{MF}=\sum(\psi_i^\dagger\chi_{ij}\psi_j+H.c.)$ description of a 2D lattice spin-model, the definition of $SU(2)$ flux $P_C$ for a l... | g15809 | [
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<p>Can a superconductor produce electricity in any condition or in any state? OR can it be used to produce electricity with the help of any other components?</p> | g15810 | [
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<p>This is not a counter-current heat exchanger.
It is two phases, Gas and Water, flow in one flow path but in opposite direction. </p>
<p>I have found many source doing analysis on flow pattern of the counter-current flow but usually stops at pressure drop topic. No one goes to Reynolds Number level, let alone the ... | g15811 | [
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<p>I'm trying to figure out if there are selection rules for the total orbital angular momentum for a system of three identical particles, say bosons. </p>
<p>For two identical bosons one can argue that the exchange symmetry implies that the state must be parity-even. From the parity properties of the spherical harmon... | g15812 | [
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<p>In their paper Specificity and Stability in Topology of Protein Networks (Science 2002) Maslov and Sneppen introduced a null-model to evaluate degree-degree correlations in networks.</p>
<p>Maslov also provides a description here:
<a href="http://www.cmth.bnl.gov/~maslov/matlab.htm" rel="nofollow">http://www.cmth.b... | g15813 | [
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<p>$$x = (\overline{x}-K)\pm \Delta x\tag{1}$$
$$\Delta x = s_{\overline{x}} = \sqrt{\frac t {\sqrt n} s_x} \tag{2}$$
$$s_x = \sqrt{\frac 1 {n-1} \sum^{n}_{i=1}(x_i-\overline{x})} \tag{3}$$
$$\frac {\Delta x}{\overline{x}}\times 100\% \tag{4}$$
$$\text{Ablolute: }U = 8.11V\pm0.02 V\tag{5}$$
$$\text{Relative: }U = 8.11(... | g15814 | [
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0.022457841783761978,
-0... |
<p>I am reading a marvelous book <em>Classical Field Theory</em> by E Soper, but it is mathematically too compact and sometimes I am unable to follow the equations. Can anyone suggest a side book for solution of my problem regarding reading the book? I also have <em>Classical Theory of Fields</em> by Landau but its con... | g98 | [
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0.056243401020765305,
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-0.007000052835792303,
0.0099... |
<p>Is there a particular name for a quantum state of the form (up to the normalization):</p>
<p>$$\sum_{i_1+\ldots+i_n = d-1} |i_1\rangle |i_2\rangle \ldots |i_n\rangle$$</p>
<p>or was it studied is some papers?</p>
<p>This state is a permutation symmetric state of $n$ qudits (i.e. $d$-level particles), and defined ... | g15815 | [
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0.010970864444971085,
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0.008752170950174332,
0.02640058845281601,
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<p>I have been recently brushing up my elementary physics concepts, specifically quantum physics. So, if I set up a single photon emitter in the double slit experiment, it is possible for me to see interference (I am assuming), when I thought about this I realized that a photon is mass-less and travels at the speed of ... | g15816 | [
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0.010142043232917786,
0.028193... |
<p>What is the most optimal earth's axial tilt in terms of variation of seasons?
What would be optimal axial tilt for earth that life would exist and change of seasons would be at minimal level?</p> | g15817 | [
0.038442131131887436,
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0.028327036648988724,
-0.01... |
<p>I read the assumption in the above question in the paper <em>Hyperbolic geometry on a Hyperboloid</em> by William F. Reynolds (see <a href="http://www.jstor.org/stable/2324297" rel="nofollow">here</a>, page 444), but it was not clarified further (the discussion was rather short). I don't have a good understanding of... | g15818 | [
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<p>Assume the force behind my throw to be X. Assume the point of release is 2 meters above ground. Asume the ball is made of shiny steel. I'm not sure if the material matters, I'm just thinking that different materials encounter different air resistance, so I'm assuming the ball is made of steel.</p>
<p>First of all,... | g15819 | [
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0.035294659435749054,
0.04050406813621521,
-0.020... |
<blockquote>
<p><strong>Possible Duplicate:</strong><br>
<a href="http://physics.stackexchange.com/questions/7063/what-actually-happens-when-an-anti-matter-projectile-collides-with-matter">What actually happens when an anti-matter projectile collides with matter?</a> </p>
</blockquote>
<p>If a large amount of a... | g487 | [
0.05801723152399063,
0.004131449852138758,
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0.006034741643816233,
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-0.06741080433130264,
0.031720586121082306,
-0.005305057391524315,
-0.04749482125043869,
0.013729466125369072,
0.020250597968697548,
0.06568022072315216,
-0.032... |
<p>X-rays mostly consist of bremsstrahlung and characteristic X-rays. What is the process called that gives rise to the latter (but not the former)?</p>
<p>I'm trying to write a sentence like "X-rays are produced by bremsstrahlung and _______."</p> | g15820 | [
0.09110501408576965,
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0.056491825729608536,
0.0156... |
<p>I'm trying to understand if there's a more systematic approach to build the matrix associated with the Hamiltonian in a quantum system of finite dimension. For example, I know that for the <a href="http://en.wikipedia.org/wiki/Ammonia">ammonia molecule</a> (which has two states based on the position of the nitrogen)... | g15821 | [
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0.01896066404879093,
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0.03995514661073685,
0.01... |
<p>Dark Energy is basically doing work against gravity to accelerate the expansion of universe. So, for time-translational symmetry to be hold, dark energy must be converted to gravitational potential energy. I don't think, it can violate critical mass condition required for Cosmic Inflation because gravitational poten... | g15822 | [
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0.004657951183617115,
0.03605470433831215,
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<p>I'm looking for a textbook in quantum mechanics that relies heavily on Green functions and the path integral formalism to supplement my QM books. I want to do some calculations using alternative methods (path integrals, green functions, Lagrangians etc).</p> | g15823 | [
0.05670345947146416,
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0.029119890183210373,
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0.044400013983249664,
-0.0172... |
<p>If the <a href="http://en.wikipedia.org/wiki/Radiant_intensity" rel="nofollow">radiant intensity</a> $I(\phi,\theta)$ of electromagnetic radiation is given in spherical coordinates ($\phi$ the azimuth, $\theta$ the polar angle, indenpendent of $R$) with units $Js^{-1}sr^{-1}$ and I integrate over the azimuth $I(\th... | g15824 | [
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-... |
<p>I couldn't understand something about the situation of a pearl that moves in a smooth vertical hoop in circular motion.
When the normal force equals 0 , the pearl didn't disconnect from the smooth vertical hoop, even though the pearl had velocity at that point.
Why the pearl didn't disconnect?</p> | g15825 | [
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0.014472433365881443,
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0.042028140276670456,
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-0.... |
<p>Consider a potential for charge distribution:</p>
<p>$$v_H(\mathbf{r}) ~=~ \int \frac{\rho(\mathbf{r'})}{|\mathbf{r}-\mathbf{r'}|}d\mathbf{r'}$$</p>
<p>where $\rho(\mathbf{r'})$ is the charge density.</p>
<p>This potential is known to be finite at any $\textbf{r}$.</p>
<p>How to prove it <em>analytically</em> ju... | g15826 | [
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0.... |
<p>I am trying to solve scattering problem in 2D and got to expand the wave function in cylindrical system which comes out to be Hankel function. Can you tell me how to expand the plane wave $\exp(i {\bf k}\cdot {\bf r})$ in terms of Hankel function, please? </p> | g15827 | [
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0... |
<p>What determines how far a telescope can see in the universe? How does recording data for a very long time (~10 years) help? If we could build a telescope which work at microwave region, will it be a better telescope (so that we could see even farther)?</p> | g15828 | [
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<p>The way dark matter is introduced to documentary watchers such as myself is to account for the difference between the rotational velocity of the stars in a galaxy compared to that of planets in stellar systems or even planetary systems (e.g. Jovian moons).</p>
<p>There is an apparent paradox here however: stellar a... | g15829 | [
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<p>A) I am intrigued by the multiverse theory as mentioned in Stephen Hawking's new book, <em>"The Grand Design"</em>. According to his theory, one can have different 'universes' in one ultimate existence, a <em>'multiverse'</em>. But what exactly differs between one universe and the other? Is it that:</p>
<ol>
<li>Th... | g15830 | [
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<p>Why does it take such a small incision for the glass to break at that spot? Why is the structural strength of the material influenced by such a small imperfection?</p> | g15831 | [
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<p>In finding the stability condition for AdS background (when gravity coupled to matter fields), why the conserved energy should be positive?</p> | g15832 | [
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<h2>Background</h2>
<p>my goal is to estimate vapor pressure deficit ($vpd$) from Relative Humidity ($rh = \frac{e}{e_s}$):</p>
<p>$$vpd = \frac{100 - \frac{e}{e_s}}{100} e_s$$</p>
<p>(from Hartmann "Global Physical Climatology)</p>
<p>But it is surprisingly difficult to find values of climatological mean $rh$ (e.g... | g15833 | [
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<p>I've had some trouble in regards to calculate the temperatures in the different states.</p>
<p>Considering the following pV-diagram:</p>
<p><img src="http://i.stack.imgur.com/j14ca.jpg" alt="enter image description here"></p>
<p>Here is the data I have:</p>
<p>The adiabatic constant $\gamma$ is 1.4</p>
<p>$C_{m... | g15834 | [
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<p>We know that 11D M-theory is described by <a href="http://arxiv.org/abs/hep-th/9610043" rel="nofollow">BFSS</a> matrix model and for M-theory on a torus $T^p$ (at least for small $p$s) the description is given by SYM theory in $p+1$ dimensions by using the dualities. </p>
<p>My question is: Does the correspondence ... | g15835 | [
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