The foundations of thermodynamics, its basic postulates and implications. A review of modern thermodynamics

Abstract

This article reviews modern theories of irreversible thermodynamics. It is known that the second law of thermodynamics is not a unique statement defined by precise rules. On the contrary, there are various versions of the second law and, likewise, also various degrees of generality to which these are exploited. All these laws express some notion of irreversibility and the implications drawn from them necessarily differ from each other. In this article we discuss these versions. They are motivated from the balance law of entropy. It is shown how the Clausius-Duhem theory, the entropy free thermodynamics of Meixner and the theory of Muller naturally follow from such a balance law. The approaches of irreversible thermodynamics and that of rational thermodynamics are compared using a simple heat conducting fluid. Muller's version of the second law, which appears to be the most general form of it, is discussed in detail. It is shown that whereever it has been applied already, its implications are farther reaching than other theories permit. Finally we discuss some criticism that has been raised against one or the other theory. — Physical arguments are emphasized and on the mathematical side the reader need only be familiar with basic calculus.