The second law of thermodynamics and special relativity

Abstract

The physical equivalence of the two major formulations of comoving, relativistic thermodynamics is stressed. Relativistic thermodynamics is generalized so that heat conduction between bodies in relative motion can be described. This new theory becomes equivalent to the earlier formulations of relativistic thermodynamics when limited to heat transfer between comoving bodies. For the first time, relativistic thermodynamics is developed in a manner which is formally identical to classical thermodynamics, e.g., an invariant quantity, called the generalized entropy, is shown to be an exact differential as a consequence of a generalized Clausius' and a generalized Kelvin's postulate. While engaged in generalizing relativistic thermodynamics a theory of frictionless heat conduction is presented, relativistic friction is discussed, and new types of Carnot cycles are described.