Nonequilibrium State

in thermodynamics, the state of a system that has been removed from thermodynamic equilibrium; in statistical physics, the state of a system that has been removed from statistical equilibrium. In a system that is in a nonequilibrium state, there occur irreversible processes that tend to return the system to a state of thermodynamic (or statistical) equilibrium if there are no impeding factors, such as the removal (or addition) of energy or matter from (or to) the system. Otherwise, a steady (constant in time) nonequilibrium state is possible. Nonequilibrium states are studied in the thermodynamics of nonequilibrium processes and in the statistical theory of nonequilibrium processes.