Deriving the Forces of Nonequilibria from Two Laws

TL;DR

This paper develops a foundational framework for nonequilibrium statistical physics by deriving forces and relations from two fundamental laws, extending equilibrium concepts to nonequilibrium systems.

Contribution

It introduces a general derivation of nonequilibrium forces and relations from two laws, replacing state entropy maximization with path entropy maximization.

Findings

Derived forces of NEQ from two laws

Established fluctuation-susceptibility equalities

Generalized to cost-benefit relations beyond work and heat

Abstract

Non-EQuilibrium (NEQ) statistical physics has not had the same general foundation as that of EQuilibrium (EQ) statistical physics, where forces are derived from potentials such as $1/T = \partial S/\partial U$, and from which other key mathematical relations follow. Here, we show how general NEQ principles can be derived from two corresponding laws. Maximizing path entropy replaces maximizing state entropy. Whereas EQ can entail observables $(U, V, N)$, dynamics has (node populations, edge traffic, cycle flux). We derive forces of NEQ, fluctuation-susceptibility equalities, Maxwell-Onsager-like symmetry relations, and we generalize to ``cost-benefit'' relations beyond just work and heat dissipation.