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Re: [Phys-L] zero point motion and E-M emission



On 06/13/2013 07:50 AM, Chuck Britton wrote:

Einstein used the zero-point vibrations to correctly explain the Specific Heat behavior at Low T.

Night Wahr?

1) I assume the question meant to ask about the /Debye/ heat
capacity. I don't mean to be unduly picky, but the Einstein
heat capacity is /not/ entirely correct. Debye was the one
who got it right.

2) Maybe I'm being denser than usual, but I don't see how the
heat capacity (Einstein, Debye, or otherwise) connects to
zero-point motion.

Even in classical thermodynamics, heat capacity depends on
/derivatives/ of the energy (or -- better -- derivatives of the
entropy) so any additive constant energy drops out.

In statistical mechanics, shifting the energy by an additive
constant shifts the partition function by a multiplicative
constant. This drops out from the per-microstate probabilities,
because it gets eaten up by the normalization. It therefore
drops out from the entropy, from the heat capacity, and from
a lot of other things.