Doru Constantin
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 Dec 15 awarded Student Sep 24 awarded Autobiographer Mar 13 awarded Yearling Jan 21 revised Do small-angle coherent scattering experiments really see coherent effects over arbitrarily large distances? added 600 characters in body Jan 21 awarded Revival Dec 30 comment Transport theorem derivation question What happened to the derivative of $J$ (which depends explicitly on time)? Dec 29 revised Distributions (e.g., Dirac Delta): confused and unhappy deleted 1 characters in body Dec 28 answered Distributions (e.g., Dirac Delta): confused and unhappy Dec 21 awarded Commentator Dec 21 comment Does coffee with cream cool slower than black coffee? I do not see how repeating that experiment would answer the question above... Dec 15 comment Expression of $\kappa_S$ in photon gas Well, you know $p(T)$, so just invert it. It is even easier to determine the adiabatic index $\gamma$, such that $pV^{\gamma} = Cst$ for constant $S$, because you can obtain $\kappa _S$ without writing down the constants explicitly. Dec 15 comment Expression of $\kappa_S$ in photon gas Try substituting in the final result the expression for $S$. You get a much simpler form, which can also be derived directly from the $V=V(p,S)$ (not that difficult, really; try it out!) Dec 13 comment Why do we get the same result using different ensembles? Saying "just replace $\bar{N}$ with $N$ in the final result" hides a non-trivial step; it actually means: "impose a chemical potential $\mu$ such that the average number of particles $\bar{N}$ is equal to the value $N$ imposed in the canonical ensemble". In a second step you can invoke the thermodynamic limit, as explained by @Abhinav to show the irrelevance of fluctuations in $N$ (in the grand-canonical ensemble) and in $\mu$ (in the canonical ensemble). Dec 11 comment Why does this integral come out imaginary? Since when is $J_0(x)$ odd ?! Dec 11 comment Using $\frac{1}{A+i\epsilon} = PV\frac{1}{A}-i\pi\delta(A)$ in Feynman Integrals Are the zeros discrete (in $(x^{\pm},y^{\pm})$) or is $f$ zero along the entire lines $y^{\pm}$ ?! What you wrote looks like the latter... Dec 10 answered Does quasi-static motion imply zero energy dissipation? Dec 10 answered FWHM in resonance amplitude square derivation Dec 10 comment Does quasi-static motion imply zero energy dissipation? Your thought experiment does not explicitly involve quasi-static motion. Are you maybe thinking of a reversible process? Dec 10 asked Does coffee with cream cool slower than black coffee? Dec 8 revised Does the weight of an hourglass change when sands are falling inside? added 233 characters in body