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After reading a number of posts here in the last few years I'm left wondering why most questions about the interpretation of quantum phenomena relate to quantum mechanics rather than the more modern ...
Valter Moretti's user avatar
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Let's say that I have built the Wigner-Seitz cell of a crystal in the real space. Is it correct to say that now, if I Fourier transform it, I obtain the First Brillouin Zone in the $k$-space?
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In an attempt to understand the Reeh-Schlieder theorem, I am currently studying this paper, in which Witten provides a discussion using the formalism of quantum field theory. It is quite ...
Valter Moretti's user avatar
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Premise Imagine we could magically / instantaneously create a void - a near-perfect vacuum - in the atmosphere (or any other similar space filled with a near-ideal gas). Question The instant after ...
spangmaed's user avatar
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5 votes
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In Wolfgang Nolting's book Theoretical Physics 2 - Analytical Mechanics, the following theorem is stated: While the formal definition of canonical trasformation is given only several pages later in ...
Qmechanic's user avatar
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3 votes
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In the case of an electromagnetic plane wave propagating in free space then incident on a flat metal surface, the electric field induces motion in the conduction electrons (or plasma). If the density ...
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I'm trying to understand how travelling at the speed of light messes with time. So pretend there is two planets one light year apart. We are in contact and plan to do an experiment. When I say 'go' on ...
Qmechanic's user avatar
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6 votes
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Excitons can be observed when we excite electrons to the conduction band. I don't know about excitons being observed when we excite the electrons to an electronic level that would eventually be in ...
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In all explanations of spontaneous symmetry breaking that I've seen, the scalar field doing the breaking is redefined/expanded around its vacuum expectation value (VEV), and similarly for the higgs ...
Qmechanic's user avatar
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This question is motivated by whether it is physically possible to have a high-quality mister for cooking oil that does not require a non-reusable pressurized can. A household spray (as in the picture ...
Elektronendompteur's user avatar
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2 answers
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I have some confusion understanding the motivation in constructing tensors (or tensor fields). On a differentiable manifold $\mathcal{M}$ consider a vector field $X$. At any point $p\in \mathcal{M}$, ...
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-3 votes
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Question edited for clarity. Matter has a four-velocity. One component of this velocity is always along the time axis, toward the future. My question is; “Why isn’t this component of the four-velocity ...
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When single electron atoms is de-excited from higher orbit to lower orbit there is a change in angular momentum. As, $$L=n\frac{h}{2\pi}.$$ I don't see any reason why it should happen as there is no ...
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Context: I am reading a paper named 'Nonrelativistic field-theoretic scale anomaly' on scale invariance in nonrelativistic field theory. The Lagrangian density for the scalar field is given by, $$\...
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78 votes
10 answers
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I've often heard the argument that having 3 spatial dimensions is very special. Such arguments are invariably based on certain assumptions that do not appear to be justifiable at all, at least to me. ...
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