# All Questions

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### Testing Many-Worlds Interpretation (MWI) with a causality-violating configuration of “superluminal cables”

Suppose we managed to arrange a causality-violating transmission of data with hypothetical “superluminal cables” (SLC; see both links for respective descriptions) and expect, similarly to ideas ...
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### Penrose diagram for spacetime which flows to $AdS_{2}$ at infinity

Consider I have the following 2 dimensional spacetime $(t,z)$: $$ds^2=\frac{4}{z^{2}}\left(1+\frac{1}{z}\right)^{-1}(-dt^{2}+dz^{2}).\tag{1}$$ When $z\rightarrow \infty$ we have ...
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### Spectrum of generic $\mathrm{CO_2}$ laser

It is often quoted, that it's emission is 10.6um. But we also know that CO2 lasers have huge number of possible emission lines in 2 main bands: 10.6um and 9.6/9.4um. But what is emission spectra of ...
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### Why aren't purely Dirac neutrinos rules out?

Its common knowledge that in neutrinos can be Dirac particles without any Majorana masses as given a mass matrix, \left( \begin{array}{cc}\nu _L & \nu _R \end{array} \right) ...
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### Horrifying electron gas model

I am given the Hamiltonian, in an exercise called plasmons, and where $\langle, \rangle$ denotes the expectation value.  H = \sum_{k} \varepsilon_k a_k^{\dagger} a_k + \sum_{k_1,k_2,q} V_q ...
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### Coordinate system for crystallographic groups

In the International Tables for Crystallography for each crystallographic group an asymmetric unit is supplied (mathematicians call this a fundamental domain of the group). This region is a bounded ...
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### Are the orientations of spin-axes and binary/planetary orbits random or is there any relationship with the Galactic plane?

In an answer to another question, a claim has been made that orbit/spin orientations are random (at least within our own Galaxy), except perhaps towards the Galactic centre. I have dabbled in this ...