question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>In quantum hall effect we measure the hall conductance (in transverse direction) which is quantized. My question how do they take care of the edge states that are in the longitudinal side? </p> | g11298 | [
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<p>I believe it is so because most of photons' energy has successfully passed the glass. But is it so? And how can I roughly estimate part of light's energy which will pass obstacles like glass?</p>
<p>And how fast beam will of light will lose energy while traveling from window's pane(What is the rate of heat loss)? T... | g11299 | [
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<p>To compactify 2 open dimensions to a torus, the method of identification written down for this example as</p>
<p>$$
(x,y) \sim (x+2\pi R,y)
$$</p>
<p>$$
(x,y) \sim (x, y+2\pi R)
$$</p>
<p>can be applied.</p>
<p>What are the methods to compactify 6 open dimensions to a Calaby-Yau manifold and how exactly do these... | g11300 | [
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<p>If you are nearsighted (like me), you may have noticed that if you <em>tilt</em> your glasses, you can see distant objects more clear than with normally-positioned glasses. <strong>If you already see completely clear, you can distance your glasses a little more from your eyes and then do it.</strong> To do so, rotat... | g120 | [
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<p>I have two questions, been trying to get definite and intuitive answers to them for some time so hopefully you can help me:</p>
<p>1) I understand both the strong force and binding energy but what is the <em>relationship</em> between the two?</p>
<p>2) What actually causes energy to be released when nuclei fuse or... | g11301 | [
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<p>Doesn't $E=mc^2$ mean that mass can be converted to energy? But from what I have studied in high school nuclear physics, it seems that the only "$E=mc^2$" we can get is from binding energy between nucleons. This may sound really stupid but is it possible to actually convert matter into energy using a machine on eart... | g11302 | [
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<p>Given</p>
<p>$$
\bar{U}_{vib}(T) = R \sum_{\text{n.m.}} \left( \frac{\theta_{vib, n.m.}}{2} \right) + \frac{\theta_{vib, n.m.} e^{-\theta_{vib, n.m.}/T}}{1-e^{-\theta_{vib, n.m.}/T}}
$$</p>
<p>where $\bar{U}_{vib}$ is the molar vibrational energy of a polyatomic molecule, n.m. refers to "normal modes" $\in \{1,2,3... | g11303 | [
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<p>I'm not a particle physicist, but I did manage to get through the Feynman lectures without getting too lost.
Is there a way to explain how the Higgs field works, in a way that people like me might have a hope of understanding?</p> | g731 | [
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<p>Tjis is a non-expert question on a (seemingly simple) text-book topic.
The question is about <strong>"hydrostatic friction"</strong>, defined as follows.</p>
<p>Consider a drop of water resting on a flat surface. If the surface is slightly
inclined, then the drop will not run off but just stay in place.</p>
<block... | g11304 | [
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<p>I'm having a hard time getting an intuitive understanding of Lorentz Contraction. I understand what it is by definition but I don't 'get it.' I'm not a physicist, just an amateur, so sorry if this question comes across as too naïve.</p>
<p>Okay, I was able to understand <em>Time Dilation</em> with the help of the '... | g964 | [
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<p>My guess is that the molecules of gas all have the same speed as before, but now there are much more collisions per unit area onto the thermometer, thus making the thermometer read a higher temperature. If this is so, then density is directly related to temperature when a substance experiences a change in density.</... | g11305 | [
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<p>When we want to compute correlation functions $\langle\Omega|\,T\hat{\phi}(x_1)\ldots|\Omega\rangle$ in an interacting quantum field theory, we relate it to the free-field objects $|0\rangle$ and $\hat\phi_I(x)$ using the interaction-picture time-evolution operator in the limit $T\rightarrow\infty$.</p>
<p>Eventual... | g11306 | [
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<p>Is there a matching material interior for the <a href="http://en.wikipedia.org/wiki/Rotating_black_hole" rel="nofollow">Kerr solution</a> of Einstein's equations?</p>
<p>I can only find informal and conflicting information about this. Some time ago, I've heard that it was expected to be a "ring of matter". A few da... | g11307 | [
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<p>I am reading now E Soper Classical Theory Of Fields now and sometimes it is very hard to follow the equations.So I need a side book to read it comfortably.Landau`s book is not helping as its content and topics are very much different.</p> | g98 | [
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<p>Recently I am reading a paper about monopoles. In several cases, it seems that writing fields in adjoint representation of the gauge group makes a difference.</p>
<p>Once it leads to different group after symmetry breaking when using other representation. And I also noticed statement like this, "An important open q... | g11308 | [
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<p><strong>I am reading Berkeley Physics Course vol. 4 (Quantum Mechanics) , chapter 4 (photons).</strong></p>
<p>(1) <strong>Section 46</strong>: book says: consider a typical photon emitted by the source. It can be regarded as a a wave train of finite duration, spreading out in all directions in space and carrying... | g11309 | [
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<p>How are the energy eigenvalues expressed in a infinite potential well problem( Joules/eV)?</p> | g11310 | [
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<p>At university we have just derived the expression for the energy split due to spin-orbit coupling in the Hydrogen atom, i.e. what is known as the FINE structure of Hydrogen. </p>
<p>To do this, we considered the situation from the frame of reference of the electron:
in this frame, the proton is moving and therefore... | g11311 | [
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<p>A question on the Uncertainty principle.</p>
<p>So we know that it says (for position and momentum) that:</p>
<p>$$ \Delta x \Delta p \ge \hbar/2 $$.</p>
<p>Where $\Delta p = \sqrt {<p^2> - <p>^2 }$ and $\Delta x = \sqrt {<x^2> - <x>^2} $;</p>
<p>NOW, Potential with a symmetry.
Imagine a... | g11312 | [
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<p>As described in many Q&As around here, fundamental quantum fields are expressed as irreducible representations of the Lorentz group. This argument is entirely clear - we live in a Lorentz-invariant world and those elements of an observed system that do not mix with others any way we transform the system, either ... | g11313 | [
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<p>Suppose we have a constant force $\overrightarrow{F}$ and in the direction of force we have 2 point $x_1$ and $x_2$ in that order. And we have to calculate work done on moving frok $x_1$ to $x_2$ and $x_2$ to $x_1$. Why and where is the following going wrong ?</p>
<ol>
<li><p>Moving from $x_1$ to $x_2$ </p>
<bloc... | g11314 | [
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<p>I wanted to investigate changes on a compact 4-manifold $M$. More specifically it is the K3-surface. I follow a paper by Asselmeyer-Maluga from 2012.</p>
<p>The idea there was to make sure that the manifold is Ricci-flat first, then Asselmyer-Maluga applies a mathematical technique that changes the differential str... | g11315 | [
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<p>In proving the total energy in conservative field is constant we have this equation(picture) why it added partial derivative? Why? I mean where it did come from?</p>
<p><img src="http://i.stack.imgur.com/xkrx5.png" alt="enter image description here"></p> | g362 | [
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<p>Please help me to solve this problem. I am unable to understand which force will cause the hoop to bounce. </p>
<blockquote>
<p>A small body $A$ is fixed to the inside of a thin rigid hoop of radius $R$ and mass equal to that of the body $A$. The hoop rolls without slipping over a horizontal plane; at the moments... | g11316 | [
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<p>Often, in papers presenting updated Lagrangian simulation methods for solid dynamics, the following procedure for updating the (Cauchy) stress tensor is presented:</p>
<p>First, the Cauchy stress tensor is split into a hydrostatic and a deviatoric part:</p>
<p>$$\sigma^{ij} = -p\delta^{ij} + S^{ij}$$</p>
<p>The p... | g11317 | [
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<p>When I place a working flashlight behind my hand, I see my hand bright red because of the light. So my question is, why do I only see red light after transmission even if incoming light from the flashlight is white? Can we explain these phenomenon mathematically?</p>
<p>Do the coefficients of absorption and transmi... | g11318 | [
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<p>Currently in my academics I am studying about the Gravitation. In the chapter I came across a term called the <strong>Escape Velocity</strong> (<em>It's the velocity of any celestial body which is required by an object to escape from body's gravitational field without any further propulsion</em>). When I was going t... | g11319 | [
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<p>We send email in order to transfer information and, over time, the technology used to send email improves to send email at faster rate.</p>
<p>Since we use the Internet to send information from one place to another place all over the world, can information speed be faster than light speed via the Internet?</p> | g11320 | [
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<p>I have read Stochastic Differential Equations by Bernt Oksendal<br/>
It constructs Brownian motion by Kolmogorov extension theorem by consider $p(t,x,y)=(2\pi t)^{-n/2} e^{- \frac{|x-y|^{2}}{2t}}$<br/>
But I can't understand what is the relation to the Brownian motion in physics.</p> | g11321 | [
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<p>Does AC current attract and DC repel our body? If the potential difference remains same will still AC and DC will give us same type of electric shock?</p> | g11322 | [
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<p>This is a follow up to <a href="http://physics.stackexchange.com/questions/64565/can-one-get-clear-ice-crystals-from-a-dirty-suspension">this question:<strong>Can one get clear ice crystals from a dirty suspension?</strong></a>.</p>
<p>How could one grow a large - meaning visible with the naked eye - water ice crst... | g11323 | [
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-0.0... |
<p>well i think the question is clear enough but I will describe more :
how datas are physically stored in and read from hard drives ? are they related with spin of atoms in the drive ? Is that method same in flash drives and SSDs?
Thanks</p> | g11324 | [
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0.07814741879701614,
-0.... |
<p>Assume two closed systems adjacent to each other together forming one adiabatic system. Both systems are assumed to have their volumes fixed and can therefore communicate with each other through heat transfer only. Now let study this simple example with three different formulation:</p>
<ol>
<li><p>The first formula... | g11325 | [
0.026394251734018326,
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0.004908672068268061,
0.0070455316454172134,
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0.017260191962122917,
0.013985580764710903,
0.07054149359464645,
0.05050915107131004,
-0.0... |
<blockquote>
<p><em>Assume that $\phi=\phi_0\gg M_{Pl}$, what can you say about the future of a universe in a model with $V(\phi)=\frac{1}{2}m^2\phi^2+\epsilon \phi$, where $|\epsilon|\ll m^2M_{Pl}^2$, is a small parameter and $m$ is such that $V(\phi_0)\approx \rho_c$.</em></p>
</blockquote>
<p>My method is:
I use... | g11326 | [
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0.004900232423096895,
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0.012786492705345154,
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-0.02932046167552471,
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0.02455831691622734,
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0.... |
<ol>
<li><p>What makes the <a href="http://en.wikipedia.org/wiki/Big_Bang" rel="nofollow">big bang</a> the biggest explosion in the universe? </p></li>
<li><p>Why even should such an explosion ever happens?</p></li>
<li><p>Through what process and how does this amount of energy get released as a big bang?</p></li>
<li>... | g11327 | [
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0.009124698117375374,
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0.03501... |
<p>I am looking for (at least) one example of the following manifolds:</p>
<ol>
<li>Flat, homogeneous and isotropic</li>
<li>Curved, homogeneous and isotropic</li>
<li>Flat, non-homogeneous and isotropic</li>
<li>Flat, homogeneous and non-isotropic</li>
<li>Curved, non-homogeneous and isotropic</li>
<li>Curved, homoge... | g11328 | [
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0.06128727272152901,
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0.03552230820059776,
-0.014... |
<p>When given two vectors $\mathbf{A}$ and $\mathbf{B}$, the curl of the cross product of these two is given by
$$\nabla\times(\mathbf{A}\times\mathbf{B})=(\mathbf{B}\cdot\nabla)\mathbf{A}-\mathbf{B}(\nabla\cdot\mathbf{A})-(\mathbf{A}\cdot\nabla)\mathbf{B}+\mathbf{A}(\nabla\cdot\mathbf{B}).$$
Using this relation, we ca... | g11329 | [
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0.043769072741270065,
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0.08602900058031082,
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0.04571204632520676,
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-... |
<p>Why can't cables used for computer networking transfer data really fast, say at the speed of light?</p>
<p>I ask this because electricity travels at the speed of light. Take Ethernet cables for example, I looked them up on <a href="http://en.wikipedia.org/wiki/Category_5_cable#Characteristics">wikipedia</a>. </p>
... | g11330 | [
0.018062744289636612,
0.051574237644672394,
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0.02196192555129528,
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0.015999026596546173,
0.0172... |
<ul>
<li>I have a granite cube made using 6 slabs of granite 1 foot square and 1 inch thick. The top and bottom slabs have a 1 inch margin around the edge. The slabs are just set together, not notched or mortared or anything.</li>
<li>I also have a concrete block with pipes running through it that generates a sonic pul... | g11331 | [
0.02999189868569374,
0.05377713218331337,
0.02238398790359497,
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0.0428367517888546,
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-0.028... |
<p>What would happen if you crushed a magnetic field to an ever decreasing size?</p>
<p>Thanks.</p>
<p>EDIT:</p>
<p>How small could the field possibly go? Is there a limit on how small it could get?</p>
<p>Is there a maximum field density based on the size?</p> | g11332 | [
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<p>I'm doing a research on <a href="http://en.wikipedia.org/wiki/Radio_frequency" rel="nofollow">RF</a> linear accelerators (RF Linac), but while studying the material I encountered many problems. I cannot understand the basics of the RF <a href="http://en.wikipedia.org/wiki/Linear_particle_accelerator" rel="nofollow">... | g11333 | [
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<p>I have this general wave equation:</p>
<p>\begin{equation}
\dfrac{\partial^2 \psi}{\partial x^2}+\dfrac{\partial^2 \psi}{\partial y^2}-\dfrac{1}{c^2}\dfrac{\partial^2 \psi}{\partial t^2}=0
\end{equation}</p>
<p>And the following transformation : $t'=t$ ; $x'=x-Vt$ and $y'=y$</p>
<p>The solution to this has to be ... | g11334 | [
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0.0352609... |
<p>So, when we are discussing Newtonian mechanics, we treat particles as point particles. In continuum mechanics, which I understand to be a version in which mass is continuously distributed, we have equivalent formulations.</p>
<p>In Special Relativity, we again formulate everything discretely (a particle has its wor... | g11335 | [
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<p>I have 2 magnets. I need to know the force between them. In a previous Phys.SE <a href="http://physics.stackexchange.com/q/81877/2451">question</a>, conclusion was: we need to use a dipole-dipole interaction equation, which included m, which the magnetic dipole. I searched how to calculate it, and this is what I fou... | g11336 | [
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... |
<p>Please note that I do not have a background in physics, so if possible please refrain from a bunch of $ |x\rangle $ notations, unless clearly specifying what it symbolically means.</p>
<p>So I have been learning about representation theory lately in particular I have studied square integrable irreducible representa... | g11337 | [
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0.... |
<p>Assume one has a gyroscope rotating around an axis with both ends leaning on a dedicated semiplane as shown on the picture below. There is no friction either between the rotor and the axis or between the axis and the semiplanes. The only force is the gravity acting on the rotor.</p>
<p>How will the gyroscope behave... | g11338 | [
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0.0044417777098715305,
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-0.0181... |
<p>A wave function is an infinite dimensional vector space, how can it "live" in $\mathbb{R}^3$?</p>
<p>Given the equation that is built like: $$\Psi (x,t) = \sum ^{\infty} _{n=1} c_n \psi _n (x) e^{-i E_n t / \hbar}$$</p>
<p>How does one "excite" a quantum particle in the lab? The excited states simply give a differ... | g11339 | [
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<p>normally meteorite hunters search for fireballs....but they totally ignore meteor showers . why so?</p>
<p>as far as i can think meteors in meteor showers are usually produced by small particles so they burn up quickly in the upper atmosphere about 30-100 km in .
but fireballs are caused by larger objects which may... | g11340 | [
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<p>Moore's law has succesfully predicted up to now that integrated circuit transister density doubles every two years. However, computer performance is dependent on additional factors like architecture, chip design and software.
What physics-related factors will enhance or limit ultimate performance of future computers... | g11341 | [
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<p>What would happen If you take a battery in a space ? Would the current flow between terminals being it in vacuum of space?</p> | g11342 | [
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<p>There has been a lot of related questions about dark energy around here but these are usually 2-4 years old and the <a href="http://physics.stackexchange.com/questions/13259/evidence-on-the-equation-of-state-for-dark-energy">closest question</a> to mine hasn't really been answered, so I am going to proceed. Experts ... | g11343 | [
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0.08493642508983612,
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0.0324767604470253,
0.003... |
<p>I have photons with a frequency distribution where one frequency is completly cut out. For example a frequency distribution like that:</p>
<p><img src="http://i.stack.imgur.com/ruoye.png" alt="enter image description here"></p>
<p>My question is: How precise can the position (frequency) of this gap be detected? In... | g11344 | [
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0.013382475823163986,
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-... |
<p>Theoretically, What is the difference between a black hole and a point particle of certain nonzero mass. Of-course the former exists while its not clear whether the later exists or not,
but both have infinite density.</p> | g11345 | [
0.04154687374830246,
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0.01732187531888485,
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<p>In dealing with the Biot-Savart law, it was argued that
$$
q\frac{d\vec{s}}{dt}\equiv Id\vec{s}
$$</p>
<p>using the fact that the units are equal. Does this kind of argument always work? It seems too simple to be true.</p> | g11346 | [
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<p>I read (I think ) that part of relativity theory is that a strong gravitational field distorts the uniform passage of time. If this is true and a lightwave 'travelling' to Earth passes a star near its intense gravitational field (a gravity 'lens') does the gravitational field distort the 'timing' of the speed of li... | g718 | [
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0.01570972055196762,
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0.006834065075963736,
0.0... |
<p>on the <a href="http://en.wikipedia.org/wiki/Equivalence_principle#Tests_of_the_weak_equivalence_principle" rel="nofollow">wikipedia article about the equivalence principle</a> there is a mention about testing the EP against parity-violating masses;</p>
<blockquote>
<p>"The equivalence principle is untested
aga... | g11347 | [
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0.009133611805737019,
0.02329392544925213,
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<p>I've heard that, in classical and quantum mechanics, the law of conservation of information holds. </p>
<p>I always wonder where my deleted files and folders have gone on my computer. It must be somewhere I think. Can anyone in principle recover it even if I have overwritten my hard drive?</p> | g11348 | [
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... |
<p>How to prove that the $\Delta L=2,$ dimension=5 Weinberg operator $LLHH$ is the unique operator which violates lepton number by two units, without derivative couplings, etc.??</p> | g11349 | [
0.0752158835530281,
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0.022073088213801384,
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0.07... |
<p>What I think is : The protons are present at the centre of the atom with rotating electrons around it so when it is rubbed by fur the electrons get passed from the ebonite rod to the fur leaving the rod negatively charged. But in reality the rod is negatively charged Why ? </p> | g363 | [
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0.0... |
<p>How is this formula derived (it is present in one of the hundred pages of my textbook about physics and fundamental physics) <img src="http://i.stack.imgur.com/l5bZ3.png" alt="enter image description here">
In the case of a system of particles $P_i$, $i = 1, …, n$, each with mass <em>mi</em> that are located in spac... | g11350 | [
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0.017125586047768593,
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... |
<p>what can cause a change in wave's shape of one dimensional wave moving through a rope?
It's velocity ? or the wave's length ? What can cause him change his shape.</p> | g11351 | [
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0.052... |
<p>I'm writing a report at the moment about natural frequency, driving frequency and resonance - and I was wondering, is there a typical % tolerance inside which the driving frequency will cause resonance (or exhibit resonance-like characteristics)? Or does this tolerance depend with the material and construct involved... | g11352 | [
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<p>I understand that angular momentum is a vector, etc..</p>
<p>But, what really happens when some object, say a ball for example, is set to rotate along two axes? What would the resulting motion look like? </p> | g11353 | [
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<p>It is a well known result of the special theory of relativity that the photon has no rest mass, because for a particle to attain the speed of light, it must have zero rest-mass. I will not dig into this more, but the interested reader can see these questions for more information:</p>
<p><a href="http://physics.stac... | g11354 | [
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<p>My question relates to Rutherford Scattering of particles. When we calculate the "differential cross-section" expression for a nucleus with finite size, it is said that the expression is almost the same as that if the nucleus was a point only a "Form Factor" multiplies,which is nothing but the fourier transform of ... | g11355 | [
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<p>How do I definitively show that there are only <strong>two</strong> propagating degrees of freedom in the Lorenz Gauge $\partial_\mu A^\mu=0$ in classical electrodynamics. I need an clear argument that</p>
<ol>
<li><p>involves the equations of motion for just the potentials $A^0$ and $\mathbf{A}$, and <em>not</em>... | g11356 | [
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<p>How to explain properties of mixture of sand with water? Why is it so coherent and slippery at the same time? Is it due to hydrogen bonds? Why is mud of smaller grains more slippery and incoherent and mud of bigger grains is more coherent and less slippery?</p> | g11357 | [
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<p>My admittedly rudimentary understanding of physical meaning of conformal flatness - as pertaining to a stationary observer exterior to a spherically symmetric static gravitating mass $M$:</p>
<p>Locally Euclidean, in that the proper differential volume $dV$ between two concentric spherical surfaces centered about M... | g11358 | [
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<p>One possible starting point to create a physical theory is the Lagrangian $L$. There we assume that the variation of the action $\delta S = \delta \int_{-\infty}^\infty dt \ L = 0$.</p>
<p>In classical theories we usually only use $q$ and $\dot{q}$ in the Lagrangian. But there are also effects like the <a href="htt... | g11359 | [
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<p>What is clear difference between say Psi_1,psi_2,....psi_4 and the U+- and V+- matrices in case of dirac fields or are u,v (or some book use U^(1),U^(2)) matrices
some rep of the same</p> | g11360 | [
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<p>I read on Wikipedia how the numerical value of Avogadro's number can be found by doing an experiment, provided you have the numerical value of Faraday's constant; but it seems to me that Faraday's constant could not be known before Avogadro's number was as it's the electric charge per mole. (How could we know the ch... | g11361 | [
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<p>Consider the <a href="http://physics.stackexchange.com/questions/12785/schrodinger-equation-in-spherical-coordinates">reduced radial Schrodinger equation</a>:</p>
<p>$$-\frac{1}{2}\frac{\text{d}^2}{\text{d}r^2}\phi(r)+V(r)\phi(r)=E\phi(r).$$</p>
<p>We try to find a bound state (i.e. $\phi(0)=\phi(+\infty)=0$).</p>... | g11362 | [
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<p>can anyone give me some good references on how to obtain the relativistic equation of particles with arbitrary spin? </p> | g11363 | [
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<p>Assuming that it's engines are incapable of dying out at 100km altitude, would mere addition of airfoil area enable a commercial liner e.g. B787 to reach that altitude?</p> | g11364 | [
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<p>In fluid dynamics, <a href="https://en.wikipedia.org/wiki/Streamlines,_streaklines,_and_pathlines">streamlines</a> are defined as line where at each point flow velocity is tangential to the line. Is it correct to say surface of a solid a streamline?
On the surface the velocity vector is zero, so it does not make sen... | g11365 | [
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<p>So I know the basic gist is that fusion power's main issue is sustaining the fusion. I also know that there are two methods. The Torus method and the laser method. The torus magnetically contains plasma and heats it with radiation and accelerates the plasma around to make strong enough collisions that protons fuse. ... | g11366 | [
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<p>It looks like most rockets that head out of Earth, or even into orbit are pencil shaped (or nearly so). I would take this to mean there is some mass of air such vehicles push out of their way. </p>
<p>What alternative shapes may a rocket headed into space, or orbit have?</p>
<p><strong>EDIT:</strong> This will pro... | g11367 | [
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<p>Assume there are two points in spacetime $a=(t,x,y,z)$ and $a'=(t',x',y',z')$. Let's say that the first one is in the origin of spacetime i.e. $a=(0,0,0,0)$. The point $a'$ has two possibilities</p>
<ol>
<li>$a'=(0,10cm,0,0)$ i.e. it's $10cm$ right of $a$</li>
<li>$a'=(1ns,1cm,0,0)$ i.e. it's $1cm$ right of $a$ but... | g11368 | [
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<p>Suppose there are two balls, one of rubber and the other metallic. There are of the same mass and are thrown on a wall with the same velocity. Why does a rubber ball bounce back while a metallic ball simply falls down after striking with the wall? I know it has got to do something with the change in linear momentum ... | g11369 | [
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<p>If two batteries, say 2 volts and 5 volts, are connected in parallel, are there any problems? The higher voltage will then want to flow out, but also towards the lower 2 volt battery end, right?</p> | g364 | [
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<p>Could you please help me to understand two statements in physics:</p>
<p>1) <strong>Universe by definition is an isolated system.</strong>
But universe expands, space pours into universe, space (vacuum) has zero-point energy, so does expansion means more energy in the universe? If yes, how can it be an isolated sys... | g11370 | [
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<p>While trying to explain to someone how a kitten walked away from a fall from a skyscraper I got to wondering if there's any place a human could do that and I find myself out of my depth.</p>
<p>The only place that seems possible is Titan but I'm not sure.</p>
<p>My basic thoughts:</p>
<p>The gravity there is abou... | g11371 | [
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<p>I know that the molecules are closer together in solids, and I know thicker springs also respond carry waves faster than thinner springs, but for some reasons I can't understand why.
The molecules will have a larger distance to move before colliding with another molecule, but in a thicker medium wouldn't that time ... | g11372 | [
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<p>I've been going through some equations and such trying to determine the work done by a solenoid on a ferromagnetic object. I have the following:</p>
<p>Magnetic field due to solenoid:</p>
<p>$\vec{B} = \langle0,0,\mu_0nI\rangle$</p>
<p>(Assuming coils are on xy-plane and current is counter-clockwise)</p>
<p>Forc... | g11373 | [
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<p>I'm writing up my physics coursework and I thought I'd try and find an equation described in the title. This is my attempt:</p>
<p><img src="http://i.stack.imgur.com/i4EEM.png" alt="Image"></p>
<p>Is it correct?</p> | g11374 | [
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<p>One might naïvely write the (anti-)commutation relations for bosonic/fermionic ladder operators as limits</p>
<p>$$
\delta_{k,\ell} = \bigl[ \hat{b}_{k}, \hat{b}_{\ell}^\dagger \bigr]
= \hat{b}_{k} \hat{b}_{\ell}^\dagger
- \hat{b}_{\ell}^\dagger \hat{b}_{k}
... | g11375 | [
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<p>From the <a href="http://en.wikipedia.org/wiki/Coriolis_effect">Coriolis Effect</a> article on Wikipedia, the following with regard to the Coriolis Effect on a rotating <strong>sphere</strong>:</p>
<blockquote>
<p>By setting vn = 0, it can be seen immediately that (for positive φ and ω) a movement due east result... | g11376 | [
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<p>I have <a href="http://home.thep.lu.se/~torbjorn/Pythia.html" rel="nofollow">Pythia</a> Monte Carlo (MC) samples where I can't understand the parton showering model. If I print out full decay chains from the events, each event contains multiple string objects with pdgId 92. There can be up to 19 strings which are ex... | g11377 | [
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<p><strong>EDIT:</strong> I edited the question to reflect Moshe's objections. Please, look at it again.</p>
<hr>
<p>It's apparently a black hole time around here so I decided to ask a question of my own.</p>
<p>After a few generic questions about black holes, I am wondering whether string theory is able to provide ... | g11378 | [
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<p>Quite a while ago I read about a series of experiments that basically suggested that a certain kind of particle/atom/(something) were "intelligent" and could appear in two places at once, or essentially could "tell the future" when it came to navigating a "maze" ...I think it might have involved lasers or mirrors?</... | g11379 | [
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<p>What does the area under a Pressure volume diagram equal? </p>
<p>I read in my textbook it equals 'external' <a href="http://en.wikipedia.org/wiki/Work_%28thermodynamics%29" rel="nofollow">work</a> done, but why is this? </p>
<p>First of all, what exactly is external work? </p>
<p>Can you get it external work by ... | g11380 | [
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<p>Is is possible to derive the Bose-Einstein density of states containing the delta function representing the BE condensate?</p> | g11381 | [
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<p>I studied that no body can travel with the velocity of light. But, assuming that when a body moves nearly velocity of light, will it obey length contraction law of Einstein or will it emit the same wavefront when it is in stationary state? What will happen to its dimensions? Will it appear same or shrink to an stat... | g11382 | [
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<p>Consider a rigid block of $b \times h$ having mass $m$ on cart (as depicted below). The cart is given an acceleration $a$, this leads to overturning of the block. The angle of rotation is indicated by $\theta$.</p>
<p><img src="https://imagizer.imageshack.us/v2/224x245q90/203/zfuy.png" alt=""></p>
<p>This is how f... | g11383 | [
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<p><a href="http://en.wikipedia.org/wiki/Leggett_inequality" rel="nofollow">http://en.wikipedia.org/wiki/Leggett_inequality</a></p>
<p>As you can see in the above link, it claims that Bell's inequality ruled out local realism in quantum mechanics, and the violation of Leggett's inequalities is considered to falsify re... | g11384 | [
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<p><a href="http://en.wikipedia.org/wiki/Leggett-Garg_inequality" rel="nofollow">http://en.wikipedia.org/wiki/Leggett-Garg_inequality</a></p>
<p>As you can see by the link above, it claims that if the violation of the Leggett–Garg inequality can be demonstrated on the macroscopic scale, it would challenge the notion o... | g11385 | [
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<p>In considering the doppler effect, why can we not just take the distance between the two as a function of time, divide by the wave velocity, and add this as a shift in our time argument of the sinusoid?</p> | g11386 | [
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<p>What is exactly meant by a statement like "there are about 400 photons per cubic cm in certain region"? Should I mentally picture this as 400 discrete photons enclosed in that volume, each moving at speed of light in that medium (independently of one another)? Also by one photon I should not mean something like a pa... | g11387 | [
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<p>For relativistic massive particle, the action is
$$S ~=~ -m_0 \int ds ~=~ -m_0 \int d\lambda ~(\dot x ^\mu \dot x_\mu)^{\frac{1}{2}} ~=~ \int d\lambda \ L,$$ where $ds$ is the proper time of the particle; $\lambda$ is the parameter of the trajectory; and we used Minkowski signature $(+,-,-,-)$. So what is the acti... | g11388 | [
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<p>I've been following the news around the work they are doing at the LHC particle accelerator in CERN. I am wondering what the raw data that is used to visualize the collisions looks like. Maybe someone can provide a sample csv or txt?</p>
<p>Edit: In addition to the raw data, it also seems that I should be intereste... | g11389 | [
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