# All Questions

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### Magnetic Field Given Magnetization

We are working on problem 6.12 from Griffiths Electrodynamics. It says that we have an infinitely long cylinder of frozen in magnetization of $M=ks\hat z$. We are trying to find the field. We have ...
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### To what extent correlation functions determines the theory (and lagranian)

In other words, does a finite set correlation functions sufficient to determine a theory? Is there a chance correlation functions are more fundamental then the lagrangian?
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### Does brightness of the light remains constant with the variation of the distance with respect to the source in vaccum?

I have this question going in my mind from many days, i.e why brightness of light emitted from any light source around us decreases with distance? The brightness of light from tube light, streetlight, ...
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### 4 of Einstein equations without 2nd order time derivative

This question is related to my previous one and it was a homework problem and was due two weeks ago. Problem：prove that four of Einsteins' equations $$G_{0\nu} = 8\pi T_{0\nu}$$ have to 2nd order ...
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### Black hole entangled with the cosmological horizon

Maldacena and Susskind recently proposed a interesting and very suggestive duality between entanglement and topological identification: http://arxiv.org/abs/1306.0533 But are such ideas applicable to ...
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### Steam bath physics

In the steam bath at the health club, why is the "steam" thicker first thing in the morning before it has been used all day and the walls are "hotter"?
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### Does greater number of lines of force around the magnet imply greater magnetic field strength around it?

If we sprinkle iron fillings on a sheet of glass placed over a short bar magnet. The arrangement of iron fillings will be similar to the one shown above. Why do some of the iron fillings ...
I have a current density operator in second quantization in the form: $\hat{J} = -i\left(\psi^\dagger \partial_x \psi - (\partial_x \psi^\dagger) \psi \right)$ operating on some state: \$|\phi ...