- #1
sayebms
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in the paper written by Jose Torres-Hernandez in 1984 titled as : "Photon mass and blackbody radiation" in the first page he writes for the partition function:
[itex] lnZ=λ \sum_{normal modes} e^{-βε_l} [/itex] = [itex] \frac{-λπ}{2} \int_{ε_0}^∞ n^2 ln(1-e^{-βε}) \frac{dn}{dε}dε[/itex]
i really don't understand how he changes the summation to the integration here, and why the integration is not inside the [itex]ln[/itex] .In 2 days i have to prepare a summary of this paper so any help is greatly appreciated.
[itex] lnZ=λ \sum_{normal modes} e^{-βε_l} [/itex] = [itex] \frac{-λπ}{2} \int_{ε_0}^∞ n^2 ln(1-e^{-βε}) \frac{dn}{dε}dε[/itex]
i really don't understand how he changes the summation to the integration here, and why the integration is not inside the [itex]ln[/itex] .In 2 days i have to prepare a summary of this paper so any help is greatly appreciated.