question stringlengths 37 38.8k | group_id stringlengths 2 6 | sentence_embeddings listlengths 768 768 |
|---|---|---|
<p>Is there a way to calculate the energy eigenvalues for a particle enclosed in an impenetrable enclosing surface? I tried evaluating the Fourier transformation of the Laplacian operator
\begin{align}
\int_V e^{-i\bar{k}\cdot \bar{x}} \nabla^2 \psi \ dV
\end{align}
to use the surface integrals to reveal the momentum ... | g15464 | [
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<p>I wasn't sure what to call this, I'm not a physicist. I basically have a collection of massive bodies. I to calculate the gravitational field of all those objects collected; how to do this? </p>
<p>The reason I want to do this is because at the end I want to see how another object will interact with that collection... | g15465 | [
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<p>I have a question from an example we done in lecture</p>
<p>Suppose we have a particle moving inside the surface of a cone given by $r = wz$ where $w$ is a constant,</p>
<p>and also suppose initially the particle is moving horizontally at height $b$ and speed $U$,the lecturer then stated these "facts"</p>
<p>$\un... | g15466 | [
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<p>I have some confusion about the concept of stationary and static.</p>
<p>A metric $g$ is called <strong>stationary</strong> if there is a time like Killing vector $K$.</p>
<p>$g$ is called <strong>static</strong> is further HSO (hyper surface orthogonal), i.e. there exists a foliation of hyper surface orthogonal t... | g15467 | [
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<p>Why is my restaurant silverware magnetized? Specifically, if I lay all three flat on the table, and touch the bottoms of the handles together, I can pull the knife with the handle of the spoon.</p>
<p>I have a video (if I can figure out how to upload it from my phone).</p> | g15468 | [
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<p>How fast (in $\frac{\mathrm{m}}{\mathrm{s}}$) are typical neutrons <em>before</em> and <em>after</em> slowing down in a nuclear reactor (with U-235 and $H_2O$ as moderator)? Do you have any reference for the values?</p> | g15469 | [
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<p>In a modern nuclear reactor for example a PWR there are multiple <a href="http://en.wikipedia.org/wiki/Nuclear_reactor_safety_systems#Containment_systems" rel="nofollow">containment systems</a> which prevent the release of radioactive material into the environment and shield the environment from the radiation.</p>
... | g15470 | [
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<p>From what I understand the Dirac equation is supposed to be an improvement on the Schrödinger equation in that it is consistent with relativity theory. Yet all methods I have encountered for doing actual ab initio quantum mechanical calculations uses the Schrödinger equation. If relativistic effects are important on... | g15471 | [
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<p>I know that the <a href="http://en.wikipedia.org/wiki/Lorentz_transformation" rel="nofollow">Lorentz transformation</a>, when two frames $\mathcal{S}$ and $\mathcal{S}'$ are in standard configuration (the axes are all parallel to their counterparts in the other inertial frame) is given by</p>
<p>$$L~=~\left(
\begi... | g15472 | [
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<p>I'm looking for sources about I guess dynamics subject.</p>
<p>The model I'd like to solve is reduced to a question of: </p>
<p>How does a force applied on a certain point of an object results in both fading rotation around point's axis and transition of the body?</p>
<p>My issue concerns objects on plane surface... | g15473 | [
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<p>Suppose I have selected enough orthogonal functions in representation of operator <code>A</code> and I want to derive operator <code>B</code> which has these functions as it's eigenfunctions.</p>
<p>How to do that?</p> | g15474 | [
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<p>I have a couple of questions about light here, and sorry of they are silly..</p>
<p>So since anything that goes beyond the event horizon can't go out, so what if a light beam was pointed somewhere behind the event horizon to the outside, would light have a slower speed then get sucked back? and what if the light pa... | g795 | [
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<p>I am not a native English speaker, and I have just started to study physics in English. However, I came across the term <strong><em>heralded photon</em></strong> while I was reading a review article about optical quantum memory. I don't understand what it means. A dictionary explains herald as, "to be a sign that so... | g15475 | [
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<p>When adding the angular momenta of two particles, you use Clebsch-Gordan coefficients, which allow you, in fancy language, to decompose the tensor product of two irreducible representations of the rotation group into a direct sum of irreducible representations. (I'm not exactly clear on what this means, so on a side... | g15476 | [
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<p>A photon is reflected by matter (by an electron in empty space). How long does the reflection take? (i.e. is there any infinitesimal time elapsing during the reflection process?), or more precisely, what is the time difference, the time retardation by the interaction compared to the light velocity in vacuum. A very ... | g15477 | [
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<p>I was wondering if it was possible to have a Non-Newtonian Gas. I was planning a science fair experiment to try to create one if its possible.</p> | g15478 | [
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<p>This is from <a href="http://rads.stackoverflow.com/amzn/click/0850861381" rel="nofollow">Problems in Thermodynamics and Statistical Physics by P.T. Landsberg</a> </p>
<p>A system can be in any one of N states. Using the method of undetermined multipliers to show for the maximum entropy, $S = -k \sum_i p_i \ln p_i$... | g15479 | [
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<p>I have seen many questions of this type but I could nowhere find the answer to "why". I know this is a phenomenon which has been seen and discovered and we know it happens and how it happens. But my question is why would wavelength affect the amount of diffraction? I am looking for a very simple logical explanation ... | g15480 | [
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<p>For a scattering process for which $n$ fermions are scattered, (by some conventions) the cross section acquires a phase space factor of:
$$d\sigma \sim \prod_{i=1}^n\frac{d^3p_i}{(2\pi)^3 2E_i}$$ </p>
<ol>
<li><p>In this convention, what is the equivalent phase space factor for an outgoing photon?</p></li>
<li><p>H... | g15481 | [
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<p>Suppose I have an electronic weighing machine placed in a uniform gravitational field. Now I put a mass above it and register the reading. Now I give the system (mass + machine) an impulse so that it travels at $0.99c$. Will the reading on the scales change and why?</p> | g15482 | [
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<p>I can't get a definitive explanation of why <a href="http://en.wikipedia.org/wiki/Superconductivity" rel="nofollow">superconductivity</a> happens and I am getting mixed explanations from my textbooks.
I will tell you what I know and hopefully you can correct any misunderstandings I have:</p>
<ul>
<li><p>A metal con... | g15483 | [
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<blockquote>
<p>A object with mass 0.5 kg slides in straight line for 200 m, where the friction act on it is 0.4 times the normal reaction acting on it. Find its initial speed.</p>
</blockquote>
<p>I let $u$ be the speed.</p>
<p>$u^2=2as=2*0.4mg*200=2*0.4*0.5*9.81*200,u=28.01ms^{-1}$.</p>
<p>But the answer should ... | g15484 | [
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<p>I'm working as an LA (undergraduate TA) for an undergraduate physics laboratory experiment where students test the Bohr model and use reduced mass to determine the approximate mass of the neutron.</p>
<p>In the experiment, a discharge tube is filled with a mixture of H and D gas, and the data that come from the spe... | g15485 | [
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<p>I know that there are several formulae that one can plug numbers into to arrive an estimate of Earth's speed around the sun (Kepler's third law for instance), but I'm wondering how these things are measured. </p>
<p>Since Earth is moving in an ellipse around the Sun, I thought doppler measurements of spectral lines... | g15486 | [
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<p>I think this question is a bit low brow for the forum. I want to take a state vector $ \alpha |0\rangle + \beta |1\rangle $ to the two bloch angles. What's the best way? I tried to just factor out the phase from $\alpha$, but then ended up with a divide by zero when trying to compute $\phi$ from $\beta$.</p> | g15487 | [
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<p>What is the physical significance of the branch cut in renormalization group logarithms?</p>
<p>(Is this just an avatar of the optical theorem, or is there something to be understood about these logarithms from the point of view of taking the scale as a complex parameter? Usually non-analyticity is a signal of some... | g15488 | [
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<p>The definition of Pohlmeyer invariants in flat-space (as per eq-2.16 in Urs Schreiber's <a href="http://xxx.lanl.gov/abs/hep-th/0403260" rel="nofollow"> DDF and Pohlmeyer invariants of (super)string</a>) is the following:</p>
<p>$ Z^{\mu_1...\mu_N} (\mathcal{P}) = \frac{1}{N} \int\limits_0^{2\pi} d\sigma^1 \int\lim... | g15489 | [
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<p>I was wondering what is the opinion about importance of the hierarchy problem in the hep community? I'm still a student and I don't really understand, why there is so much attention around this issue. </p>
<p>1 loop corrections to the Higgs mass are divergent - in the cut-off regularization proportional to $\Lambda... | g15490 | [
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<p>I'm trying to understand some aspects of dS/CFT, and I'm running into a little trouble. Any help would be much appreciated.</p>
<p>In <a href="http://arxiv.org/abs/1104.2621" rel="nofollow">arXix:1104.2621</a>, Harlow and Stanford showed that the late-time Hartle-Hawking state in de Sitter space,
\begin{align*}
\P... | g15491 | [
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<p>I've been reading a few papers on generalized probabilistic theories, and have been struggling through proofs of some results that involve use of convexity and group theory, e.g. <a href="http://arxiv.org/abs/1110.3516" rel="nofollow">this paper on bit symmetry</a> and many others. Is there a set of introductory lec... | g15492 | [
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<p>I have a black box with an arbitrary mass distribution inside it. I want to replace that object with n point masses without changing any mechanical properties of the box (center of mass, total mass, moment of inertia tensor). What is the fewest number of points I need and how can I find them?</p>
<p>I count 10 con... | g15493 | [
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-0.02970527857542038,
0.03660968691110611,
-... |
<p>I understand that one way to tell how much a liquid will be heated up by a remote heat source is by looking at its color. I assume clear and colorless heats up least, then white, other colors and last black liquids will heat up the most. ( Is this right and can more detail be added?)</p>
<p>However I don't understa... | g15494 | [
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<p>Every time I go through some literature about Larmor Precession, i.e. the precession of orbit charged particle in the presence of a Magnetic Field. It doesn't give convincing arguements in calculating the Larmor frequency. Mostly in the books if the mathematics is taken care, it physically makes no sense to me or vi... | g15495 | [
0.04992295429110527,
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<p>In the Heisenberg model of ferromagnetism the atoms are assumed to be arranged in a lattice.
The $i$-th atom has a spin operator $\vec S_i$ (here $i$ belongs to the lattice). The Hamiltonian is given by
$H=-J\sum_{<ij>}\vec S_i\cdot\vec S_j$ where the sum runs over all pairs of atoms connected by an edge, $... | g15496 | [
0.044698603451251984,
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0.036573950201272964,
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0.020767949521541595,
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-0.0... |
<p>Someone here recently noted that <em>"The spin-statistics thing isn't a problem, it is a theorem (a demonstrably valid proposition), and it shouldn't be addressed, it should be understood and celebrated.</em>"</p>
<p>"Spin statistics" is of course the shorthand way of referencing a most curious fact about the unive... | g15497 | [
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0.0025... |
<p>I know that a polytropic process equation is often the result of an empirical fit of a P-V curve that allows one to derive some nice analytical equations for the process. Is there actually a derivation for the polytropic process equation?</p> | g15498 | [
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<p>i was a little confused about the casimir effect. my understanding is with the 2 plate experiment there was a force pushing the plates together because there were less virtual particles in between the plates than outside them. Why are there less particles in between the plates?</p> | g15499 | [
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<p>I am looking into the effects of gravitational lensing of gravitational waves. I know that gravitons travel along null geodesics, just as photons, and so they will suffer the same deflection angle by a massive close to their paths </p>
<p>I think I know what <em>microlensing</em> is, with the impact parameter, Eins... | g15500 | [
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<p>I purchase an espresso shot each morning at my local coffee shop, and I usually water it down slightly to take the edge off as well as to cool it. Recently, I have noticed that when I pour the cold water in, it seems that the surface of my espresso is suddenly disturbed in a lattice-like configuration
\begin{align*}... | g15501 | [
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<p>I am currently working on a <a href="http://en.wikipedia.org/wiki/Tight_binding" rel="nofollow">Tight-Binding model</a> and for the derivation of nearest neighbor spin interactions I have terms like
$$
\left<x\uparrow\right|\eta\;\mathbf{l}\cdot\mathbf{s}\left|z\downarrow\right>
$$
where $\left|x\uparrow\right... | g15502 | [
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0.02431868575513363,
0.006805454380810261,
-0.... |
<p><a href="http://physics.schooltool.nl/quantumoptics/rabi_rabimodel.php" rel="nofollow">This page</a> on Rabi oscillation says the Hamiltonian has an interaction term $d \cdot E(t)$, where $d = -$e$r$. (I'm sure what they mean is, that's what the off-diagonal terms of the Hamiltonian look like).</p>
<p>What is $r$? ... | g15503 | [
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<p>What are <a href="http://en.wikipedia.org/wiki/Twistor_theory">Twistors</a>? Why are they important?</p>
<p>This particular statement in Wikipedia is intriguing</p>
<blockquote>
<p><em>According to Andrew Hodges, twistor space is useful for conceptualizing the way photons travel through space, using four complex... | g15504 | [
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<p>Suppose a thermally insulated container is filled with atmospheric air until the pressure reaches 5000 psi. This could represent the filling of a diving cylinder, before thermal dissipation becomes significant.</p>
<p>Initially, then, some mass of air has atmospheric temperature $T_1$ and $p_1$. When forced in to... | g15505 | [
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<p>I have learned about the existence of positrons as a decay product from uranium fission - if I'm not mistaken. Is there any evidence for higher 'mass' anti-matter, or is that mere speculation or rationalisation? i.e. Is the argument that there anti-matter based planets in the universe, or just a soup of positrons?</... | g15506 | [
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<p>In electromagnetics the intensity of a wave is calculated taking the squared of its amplitude. What is the reason why in quantum waves this cannot be applied to calculate it?</p> | g15507 | [
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<p>The <a href="http://en.wikipedia.org/wiki/Thomson%27s_lamp" rel="nofollow">thought experiment</a> goes like this: </p>
<blockquote>
<p>Say there is some circuit which turns a lamp on/off with just a flick
of a switch. Say its off; you flick it, it turns on; flick it again it
turns off, and so on. </p>
<p... | g15508 | [
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<p>This might be a stupid question but given Einstein's general theory of relativity $E = m c^{2} $ what is the energy of a black hole? Isn't the mass of a black hole infinite? Wouldn't that be infinity multiplied by the speed of light squared? </p> | g15509 | [
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<p>I am extremely weak in visualizing physical problems in mathematical context. Please help me in solving the following problem and please give as much details as possible.</p>
<p>A fluid flows radially (& isotropically) outward from a faucet of radius a into a 2‐D plane at a volume
flow rate of $\dot{V}=\alpha$ ... | g15510 | [
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<p>I am looking for a set of differential equations (to be solved numerically for an educational program) that would describe the position and apparent time of an accelerated clock relative to a non-inertial reference frame. For now, all movement is along a single spatial dimension. I am <em>not</em> interested in cons... | g15511 | [
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<p>trying to read a bit about "quantum nucleonics", i've encountered <a href="http://www.eurekalert.org/pub_releases/2001-08/llnl-pcr081301.php">this rebuttal from people at Livermore</a> that induced radiation stimulation of Hafnium nuclei is possible. Something that catches my eye is the phrase "The earlier reports w... | g15512 | [
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<p>I (as I am sure you will be able to tell) know very little about nuclear physics, so please understand if something here seems dumb or obvious.</p>
<p>I am going to question some Hollywood physics here. At the end of Spiderman 2, Octavius tells Spiderman to drop what essentially amounts to a tiny star into the riv... | g15513 | [
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<p>I have a laser with an intensity distribution $I(\lambda)$ over a broad wavelength range (arroun 40 nm), I want to calculate the total scattering rate due to the full spectrum of the laser; the the scattering rate is given by</p>
<p>$\gamma_p(\lambda) = \gamma \rho_{ee}(\lambda) = \frac{\gamma}{2}\cdot\frac{A(I(\la... | g15514 | [
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<p>Of course it depends on the distance and the amount of radiation, so let's say its about 10,000 Rad. Now, can wall made of brick protect someone behind it from such radiation ? </p> | g15515 | [
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... |
<p>If space were to expand at > $c$ (as in inflation) would that mean gravity would no longer have any effect on the curvature of space, since gravity can only propagate at $c$?</p> | g15516 | [
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<p>How to compute the change in entropy of s system when the temperature is decreasing? Such a question may be too general,then we may ask a special case:How to compute the change in entropy of Annealing system when such a process may be regarded as Markov Chain ?</p> | g15517 | [
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<p>There are some principles in entropy im having trouble understanding. If Entropy requires that the energy in the universe must always been constant, shouldnt in theory 'Heat Death' have occurred since forever ago even before the Big Bang? Why not?</p>
<p>Thank you!</p>
<p>[UPDATE]</p>
<p>Entropy and energy conser... | g15518 | [
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<p>The relevant figure is below (taken from Goldstein's Classical Mechanics). This figure plots the effective potential for a gravitational force. Does the effective potential $V'$ go flat below $E_2=0$? After finding $r_{flat}$, the point where the effective force $f'=0$ (or equivalently, where $V'$ goes flat), I got ... | g15519 | [
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-0.... |
<p>Consider quantum Hamiltonian of free massive scalar particle:
$$\hat{H} = \int d^3x \left[\frac{1}{2} \hat{\pi}^2 (t, \vec{x}) + \frac{1}{2} \partial_i \hat{\phi}(t, \vec{x}) \partial_i \hat{\phi}(t, \vec{x}) + \frac{m_0^2}{2} \hat{\phi}^2(t, \vec{x}) \right].$$
I'd like to show that Heisenberg evolution equation fo... | g15520 | [
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<p>I have read a little about Quantum computing.</p>
<p>From what I understand, Quantum Superposition is when a qubit is in a state $\alpha|0\rangle$ + $\beta|1\rangle$, where $\alpha$ and $\beta$ are probability amplitudes. Now when we try to measure or see the qubit it collapses to a 0 or 1.</p>
<p>Why don't we con... | g15521 | [
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<p>Yesterday, I understood what it means to say that the moon is constantly falling (from <a href="https://www.youtube.com/watch?v=j3mhkYbznBk#t=1220s">a lecture by Richard Feynman</a>). In the picture below there is the moon in green which is orbiting the earth in grey. Now the moon wants to go at a tangent and travel... | g15522 | [
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<p>This is a pretty basic conceptual question about the conservation of linear momentum. </p>
<p>Consider an isolated system of 2 fixed-mass particles of masses $m_1$ and $m_2$ moving toward each other with velocities $v_1(t)$ and $v_2(t)$ respectively. </p>
<p>Now conservation of momentum says that at any point duri... | g15523 | [
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<p>I tried to check the Lorentz invariance of the standard special relativity action for free particle <strong>directly</strong>: ($c=1$)</p>
<p>$$
S=\int L dt=-m\int\sqrt{1-v^{2}}dt
$$</p>
<p>Lorentz boost:</p>
<p>$$ dt=\frac{dt^{'}+udx^{'}}{\sqrt{1-u^{2}}}$$, $$dx=\frac{udt^{'}+dx^{'}}{\sqrt{1-u^{2}}}$$, $$v=\f... | g15524 | [
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0.09119253605604172,
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-... |
<p>The energy stored in the electric field of a uniformly charged non-conducting shell moving with a uniform velocity is more than the energy stored in the electric field of the same shell at rest. What is the source of this extra energy?</p> | g15525 | [
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<p>Bosonic solutions of eleven-dimensional supergravity were studied in the 1980s in the context of Kaluza-Klein supergravity. The topic received renewed attention in the mid-to-late 1990s as a result of the branes and duality paradigm and the AdS/CFT correspondence.</p>
<p>One of the earliest solutions of eleven-di... | g15526 | [
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<p>This question is related to <a href="http://theoreticalphysics.stackexchange.com/questions/61/mermin-wagner-theorem-in-the-presence-of-hard-core-interactions">that one</a>. I ask it here since comments are too short for the extended discussion that was going on there.</p>
<p>I am interested in a very simple interfa... | g15527 | [
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<p>Many years ago, when <a href="http://en.wikipedia.org/wiki/CSS_code">CSS codes</a> were first invented, the error threshold of p=0.11 was found when bit and phase flips are independent. Has a threshold yet been found for the case of depolarizing noise?</p> | g15528 | [
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<p>I am considering the Heisenberg XXZ model at the moment. In the literature it says that (in the $J\Delta\rightarrow\infty$ limit, i.e. the ferromagnetic Ising regime) one can either view low-energy excitations as magnons (single overturned spins), or as domains of consecutive flipped spins, named spinons. The latter... | g15529 | [
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<p><img src="http://i.stack.imgur.com/Yn0Jn.jpg" alt="http://bm.img.com.ua/img/prikol/images/large/4/0/258204_603914.jpg"></p>
<p>What is the deepest tunnel in the Earth's surface? </p>
<p>I have meet numbers, around 300km. </p>
<p><strong>What is the main problem to make tunnel more deeper? What is the problem with... | g15530 | [
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<p>For the hydrogen atom, if
$\int|u|^2\ \mbox{d}x=1$
show that the same is true at all later times.</p>
<p>Hint: Differentiate the integral with respect to t, taking care about the solution being complex valued. assume that $u$ and $\nabla u\rightarrow \infty$ fast enough as $|x|\rightarrow\infty$.</p> | g15531 | [
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<p>Object B is 15 degrees East of North at a distance of 20km/h. Object B is moving at an average speed of 30km/h in the direction 40 degrees East of North. If object A is capable of moving at 100km/h, at what angle does it need to move to intercept object B?</p>
<p><img src="http://i.stack.imgur.com/O2qUC.jpg" alt="o... | g15532 | [
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<p>Can you please draw me the figure of the problem? I dont want the solution,just the figure?</p>
<p><strong>A straight, stiff, horizontal wire of length
25 cm and mass 50 g is connected to a source of emf by light,
flexible leads. A magnetic field of 1 .33 T is horizontal and
perpendicular to the wire. Find the curr... | g15533 | [
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0.0... |
<p>I was playing with
$$M=\frac{m_0}{\sqrt{1-v^2/c^2}}$$
and when I put $v=c\sin\theta$, I got
$$M=m_0\sec\theta.$$
And this new equation is appearing so beautiful and attracting to me that I was compelled to think whether $\theta$ appearing here has any physical significance or it is just a mathematical artifact? Wh... | g15534 | [
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<p>thanks for any help.</p>
<p>I'm trying to show that in a 2body problem, angular momentum is conserved given that $\dfrac{dp}{dt}=\dfrac{-GMm(rv)}{r³}$, where p is momentum, t time, G gravitational constant, M mass of 1 object, m mass of the other, (rv) is the vector between them and r is the magnitude of the vector... | g478 | [
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<p>I have a question about the interpretation of the Doppler effect, when you look at the results as a change in octaves. Nothing actually changes when you look at the result in octaves instead of frequency shift, obviously, but it suddenly seems a whole lot less intuitive. This makes me wonder whether I understand thi... | g15535 | [
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<p>I understand that Noether's Theorem has a Hamiltonian form, whereby {X, H} = 0 iff {H, X} = 0. </p>
<p>The proof of this is trivial, as it follows from the antisymmetry of the Poisson Brackets. </p>
<p>First question: </p>
<p>It remains a question on my mind whether every symmetry, which transforms q(t) into q(... | g15536 | [
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0.05027693137526512,
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<p>In classical relativistic Electrodynamics, we are often told that any accelerating point charge inherently radiates (Bremstrallung). (This is the basis for the need for a QM conception of electrons.)</p>
<p>We are also told that the innate (not due to the fields) energy of a moving particle is based on relativity, ... | g15537 | [
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<p>I'm facing a dead end with my physics experience on a new build I am working on. Any help would be appreciated.</p>
<p>Basic problem:</p>
<p>I am trying to build a floating wooden <a href="http://en.wikipedia.org/wiki/Torii" rel="nofollow">Torii gate</a> to be placed on water in a way that the structure's original... | g15538 | [
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<p>As pointed out <a href="http://physics.stackexchange.com/questions/105353/why-must-the-particles-of-an-ideal-gas-be-point-like/105354#105354">here</a> point-particle-based modeling can lead to very inaccurate predictions.</p>
<p>Could you give an example where point-particle-based model describes reality accurately... | g15539 | [
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0.02437722310423851,
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0.05971505492925644,
-0.01488... |
<p>Knowing that degeneracy occurs in n-dimensional infinite potential well where two wave functions correspond to the same energy, can the same be said for the finite potential well?</p> | g15540 | [
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<p>In my textbook, there is a feynman diagram showing top + anti-top pair production with a highly energetic gluon resulting from the fusion of two gluons.</p>
<p>I know that all vector bosons have spin 1, so how is the spin quantum number conserved in this interaction?</p> | g15541 | [
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0.041825469583272934,
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<p>For a particle in potential $U(x)$ in 1D which equation is correct</p>
<p>$$i\hbar\frac{\partial\psi}{\partial t}=(cp \sigma_x+mc^2\sigma_z+U(x))\psi$$
or
$$i\hbar\frac{\partial\psi}{\partial t}=(cp \sigma_x+mc^2\sigma_z+U(x)\sigma_z)\psi$$</p> | g15542 | [
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<blockquote>
<p>Simple pictures showing orbital shapes are intended to describe the
angular forms of regions in space where the electrons occupying the
orbital are likely to be found. The diagrams cannot, however, show the
entire region where an electron can be found, <strong><em>since according to
quantum me... | g15543 | [
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<p>So I looked for some explanations, how I understand it so far is that the Higgs field causes particles to have mass by drag, like drag force in water, which prevents objects from moving at the speed of light, is that correct? so is the Higgs field essentially an element that makes up space?</p> | g15544 | [
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<p>If there was a universe with the same laws as this one, but there were only bosons in it, would QM 'do anything'? </p>
<p>Would there be any QM effects - such as an energy level (but that would require fermions..).</p> | g15545 | [
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0.03... |
<p>Whether gravitational waves are real or just a coordinate freedom was argued in the early days of GR. Eventually the conclusion was that they were real. And if they are 'real' then I'm curious if...</p>
<p>Has it ever been shown that in General Relativity, two (or more) colliding gravitational waves can lead to a... | g15546 | [
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0.014602701179683208,
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0.025725262239575386,
-0.00... |
<p>From a recent <a href="http://www.sciencedaily.com/releases/2011/09/110915144828.htm" rel="nofollow">ScienceDaily</a> article, we have this...</p>
<blockquote>
<p>Scientists detected the new planet in the <a href="http://en.wikipedia.org/wiki/Kepler-16" rel="nofollow">Kepler-16</a> system, a pair of
orbiting st... | g15547 | [
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0.02640107274055481,
0.03616592288017273,
0.04543134570121765,
0.0114... |
<p>Kind of an odd question here.</p>
<p>First let's define what an "average" nuclear explosion is, because that's quite a controversial term - "average". Considering that <a href="http://www.brookings.edu/FP/PROJECTS/NUCWCOST/TESTS.GIF" rel="nofollow">the peak of nuclear tests was at the 1960s</a>, and that the bulk o... | g15548 | [
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0.04102139547467232,
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0.02134351059794426,
-0.... |
<p>Stellar spectra captured from ground based equipment needs corrections to remove atmospheric spectral noise. Is there an Internet site that shows specific amplitude and wavelength differences between an observed spectrum and a corrected stellar spectrum?</p>
<p>The Dec, 2011 issue of <a href="http://en.wikipedia.or... | g15549 | [
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0.002212393330410123,
0.07577688246965408,
0.023242710158228874,
0.038067761808633804,
0.0... |
<p>If I charge two capacitors which are connected parallel $[$the minus (-) of the one opposite to the minus (-) of the other and the plus(+) of the one opposite to the plus (+) of the other.$]$, will I get current (charge flowing) after adding a dielectric material to one of them ?</p> | g15550 | [
0.05105775594711304,
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0.005432650446891785,
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0.06508699804544449,
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-... |
<p>I've been searching and have not been able to find a formula for calculating the impedance of differential lines on inner layers where the dielectric above and below it is not symmetrical. I've seen plenty of examples of symmetrical stackups, but that would not help in my case.
Does anyone know what the formula wou... | g15551 | [
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0.0011110970517620444,
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0.001356207299977541,
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0.027536390349268913,
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0.0027025968302041292,
-0.06746028363704681,
0.022845443338155746,
-0.025410471484065056,
... |
<p>I'm working on a basic simulation system which will include planets with rings, I want to create dust and asteroids within a 3D ring but I'm struggling to find any stats on the sort of height ranges a ring might have (I can find inner and outer radius estimates, but not the height ranges).</p>
<p>Does anybody know ... | g15552 | [
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0.062049705535173416,
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0.011031894944608212,
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-0.011009245179593563,
0.006120702251791954,
0.024250106886029243,
0.06713250279426575,
-... |
<p>Using ground-based telescopes or the <a href="http://en.wikipedia.org/wiki/Hubble_Space_Telescope" rel="nofollow">Hubble Space Telescope</a>, astronomers take photographs of galaxies which are many light years from the Earth. Does it mean those photographs are as old as the galaxies are far from the Earth? </p>
<p>... | g15553 | [
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0.02694038487970829,
-0.0026976498775184155,
0.07408580183982... |
<p>I'm trying to figure out how much oxygen the <a href="http://scifi.stackexchange.com/questions/13727/how-much-air-does-johnny-burn">Human Torch</a> produces when he is on fire. I figure if I knew how much oxygen on average (per second?) is consumed by a 1 cm squared surface which is producing flame ( rapid combustio... | g861 | [
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0.010022471658885479,
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-... |
<p>Can someone please help me understand and answer the question of "why are the forces on a magnetic dipole different in a uniform magnetic field and non-uniform magnetic field?" I know in a uniform magnetic field the magnetic dipole material will tend to align with the field lines of the magnetic field it is in but w... | g15554 | [
-0.04829173907637596,
0.0403866246342659,
-0.012624808587133884,
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<p>What level of knowledge and in what areas would be required to perform experimental work with an SEM (Scanning Electron Microscope) and a TEM (Transmission Electron Microscope) respectively? E.g. would a strong background in quantum mechanics be necessary for EELS (Electron Energy Loss Spectroscopy) using a TEM?</p>... | g15555 | [
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<p>I see that many websites and magazines with physics thematic are pretty excited about mining Helium 3 isotope on the Moon. But this seems to be a very hard-to-get resource. For more than one reason:</p>
<ol>
<li>There is not too much of it on the moon. <a href="http://www.rocketcityspacepioneers.com/space/mining-th... | g15556 | [
0.014221176505088806,
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<p>I'm having some trouble figuring this out, so I was hoping someone could help.</p>
<p>I need to show that the first-order pertubation of the ground state energy is not changed by the pertubation $H'$, given by a constant electric field in the z-direction:</p>
<p>$H' = eEz$</p>
<p>Now, the first-order pertubation ... | g15557 | [
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<p>According to many sites like <a href="http://www.pagetutor.com/jokebreak/091.html" rel="nofollow">this one</a>, an ant can apparently lift 50 times its own weight and pull 30 times its weight. Is it true?</p>
<p>Can it be proved using physics? Though most sites agree that an ant can lift many times its own weight,... | g15558 | [
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<p>I was reading in the papers how some-airline-or-the-other increased their prices for extra luggage, citing increased fuel costs.</p>
<p>Now I'm a bit skeptical. Using the (wrong) Bernoulli-effect explanation of lift, I get this:</p>
<p>More luggage$\implies$more lift needed $\implies$ more speed needed$\:\:\:\not ... | g15559 | [
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<p>The most important property of an antenna, beyond its conductivity(?) seems to be it's length (or more generally, its shape). But the antenna device is connected to the receiver by an arbitrarily-long connector. What is the fundamental difference between an antenna and the connector? Why doesn't the connector's l... | g15560 | [
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-0... |
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