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03:39
2
Q: Leibniz rule and Nakahara's definition for functional derivatives with respect to Grassmann variables

TheFoxIn Nakahara's book "Geometry, Topology and Physics" in section 1.5.7 (I'm reading the second edition) he defines the functional derivative with respect to Grassmann variables. He does so in a similar way he defined that with respect to $c$-numbers, as $$ \frac{\delta F[\psi(x)]}{\delta \psi(y)} =...

definition differentiation fermions grassmann-numbers functional-derivatives
 
1 hour later…
HNQ
HNQ
04:46
2
Q: Cherenkov radiation in the frame of a moving observer

Dr. user44690Imagine a medium in which an electron is moving at speeds faster than the speed of light in the medium. Within the same medium an observer moves at the same speed with the electron. Will the observer detect Cherenkov radiation from the electron in his frame? I think the answer is no because the e...

special-relativity cherenkov-radiation
 
17 hours later…
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HNQ
21:57
1
Q: If we apply a constant perpetual perpendicular force on a brick kept on a floor, will it deform the brick?

SacrificialEquationSuppose a brick is kept on a floor and we apply a constant perpendicular pressure on it for an indefinite period, will it cause the brick to deform in any way? Assume the pressure is small enough to not to break it immediately. Brick is brittle and pressure is applied by any material which can wi...

forces material-science elasticity stress-strain

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