Non-Equilibrium Statistical Physics: an Overview

Many natural systems, far from thermodynamic equilibrium, keep on exchanging matter, energy or information with their surroundings. These exchanges produce currents, or fluxes, that break time-reversal invariance. The physics of such systems lie beyond the realm of traditional thermodynamics and the principles of equilibrium statistical mechanics do not apply. In fact, there exists no general conceptual framework \`a la Gibbs-Boltzmann to describe these   systems from first principles. The last two decades, however, have witnessed   remarkable progress. The aim of this colloquium   is to review some   recent developments, such as the Work Identities (Jarzynski, Crooks), the Fluctuation Theorem (Cohen, Evans,   Gallavotti and Morriss) and the Macroscopic Fluctuation Theory (G. Jona-Lasinio et al.) which represent the first steps towards a unified approach of   non-equilibrium behaviour.