Entropy as Noether charge for quasistatic gradient flow

Abstract

Entropy increase is fundamentally related to the breaking of time-reversal symmetry. By adding the 'extra dimension' associated with thermodynamic forces, we extend that discrete symmetry to a continuous symmetry for the dynamical fluctuations around (nonlinear) gradient flow. The latter connects macroscopic equilibrium conditions upon introducing a quasistatic protocol of control parameters. The entropy state function becomes the Noether charge. As a result, and following ideas expressed by Shin-ichi Sasa and co-workers, the adiabatic invariance of the entropy, part of the Clausius heat theorem, gets connected with the Noether theorem.