On the Reciprocal Relations of Onsager

Abstract

Given any linear relation between forces and fluxes in irreversible thermodynamics, it is shown that redefinition of forces and fluxes by linear combination yields a relation with symmetric matrix. The rate of production of entropy is unchanged by the redefinition. Thus, unless ``forces'' and ``fluxes'' are defined by some property more specific than mere occurrence in the expression for production of entropy, there is no content in the statement that the matrix of phenomenological coefficients is or is not symmetric.