31. Classical thermodynamics postulates the existence of systems in their own states of internal thermodynamic equilibrium . 32. One may imagine two such cavities, each in its own isolated radiative and thermodynamic equilibrium . 33. For example, local thermodynamic equilibrium in a liquid is reached within a few collision times. 34. It is not known however whether it eventually achieves thermodynamic equilibrium . [ 34 ], 35. This article is focused mainly on classical thermodynamics which primarily studies systems in thermodynamic equilibrium . 36. Very strong incident radiation or other factors can disrupt thermodynamic equilibrium or local thermodynamic equilibrium. 37. Very strong incident radiation or other factors can disrupt thermodynamic equilibrium or local thermodynamic equilibrium . 38. The main result of this paper is that this thermodynamic equilibrium should be a KMS state. 39. Systems in thermodynamic equilibrium are always in thermal equilibrium, but the converse is not always true. 40. The ISM is usually far from thermodynamic equilibrium .
