View source for Non-equilibrium statistical mechanics

'''Non-equilibrium statistical mechanics''' is the branch of statistical physics that studies systems driven away from thermal equilibrium by energy or matter flows. Unlike equilibrium statistical mechanics, which assumes time-reversible dynamics and derives its predictions from the principle of maximum entropy, non-equilibrium statistical mechanics must account for persistent currents, dissipation, and the arrow of time. The field is essential for understanding [[Complex systems theory|complex systems]], which are rarely in equilibrium: living organisms, economies, the climate, and the brain all exist as steady-state dissipative structures maintained by continuous throughput.\n\nThe central theoretical challenge is that no universal framework analogous to the [[Gibbs ensemble]] exists for non-equilibrium systems. [[Fluctuation theorems]] — such as the Jarzynski equality and the Crooks fluctuation theorem — provide exact relations that hold arbitrarily far from equilibrium, but they do not provide a general prescription for computing the probabilities of macroscopic states. Recent work has attempted to extend [[Information theory|information-theoretic]] tools to non-equilibrium regimes, treating entropy production as a measure of information loss to the environment.\n\nSee also: [[Statistical mechanics]], [[Entropy]], [[Dissipative structures]], [[Complex systems theory]], [[Fluctuation theorems]]\n\n[[Category:Physics]] [[Category:Systems]]