(adsbygoogle = window.adsbygoogle || []).push({}); "Speed of time": temperature tells thermal time/proper time (Smerlak Rovelli)

IMHO this is an elegant 4-page gem. Check it out.

http://arxiv.org/abs/1005.2985

Thermal time and the Tolman-Ehrenfest effect: temperature as the "speed of time"

Carlo Rovelli, Matteo Smerlak

(Submitted on 17 May 2010)

"The thermal time hypothesis has been introduced as a possible basis for a fully general-relativistic thermodynamics. Here we use the notion of thermal time to study thermal equilibrium on stationary spacetimes. Notably, we show that the Tolman-Ehrenfest effect (the variation of temperature in space so that [tex]T\sqrt{g_{00}}[/tex] remains constant) can be reappraised as a manifestation of this fact: at thermal equilibrium, temperature is locally the rate of flow of thermal time with respect to proper time - pictorially, 'the speed of (thermal) time'. Our derivation of the Tolman-Ehrenfest effect makes no reference to the physical mechanisms underlying thermalization, thus illustrating the import of the notion of thermal time."

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# Speed of time : temperature tells thermal time/proper time (Smerlak Rovelli)

**Physics Forums | Science Articles, Homework Help, Discussion**