A fourth law of thermodynamics

Abstract

Classical thermodynamics, based on conservation of matter and energy and on the increase of entropy accompanying every natural event, reliably predicts equilibrium properties of macroscopic systems, regardless of the complexity of those systems. Thermodynamic theory historically has had little to say about the far-from-equilibrium evolution of systems. This is in part because the classical laws of thermodynamics, limited to requirements about the degree and direction of change, are silent about the means and pathways for achieving change. We propose a simply stated yet powerful Fourth Law of Thermodynamics that significantly extends the domain of thermodynamics by incorporating evolving systems and thereby adding richness to thermodynamic description.