Onsager principle of microscopic reversibility and supersymmetry

The Onsager principle of microscopic reversibility is shown to be at the origin of the hidden supersymmetry recently discovered in parabolic stochastic differential equations (Langevin equation). The celebrated "Kelvin reciprocity relations," for thermodynamic processes out of the equilibrium, are derived from the requirement of having a supersymmetric Fokker-Planck dynamics. On the same line, the well-known fluctuation-dissipation theorem is obtained as a Ward identity of this hidden supersymmetry.