On the nonequilibrium entropy of large and small systems

Understand

Thermodynamics makes definite predictions about the thermal behavior of macroscopic systems in and out of equilibrium.

• Statistical mechanics aims to derive this behavior from the dynamics and statistics of the atoms and molecules making up these systems.
• A key element in this derivation is the large number of microscopic degrees of freedom of macroscopic systems.
• Therefore, the extension of thermodynamic concepts, such as entropy, to small (nano) systems raises many questions.