PRINCIPLE OF LEAST ACTION AND IRREVERSIBILITY

Abstract

In order to solve the problem of substantiating the empirical laws of physics associated
with the irreversibility of natural processes, based on the fundamental laws of physics, we consider the
relationship between the principle of least action of classical mechanics and the principle of maximum
entropy in thermodynamics. It is shown that the state of a system with maximum entropy corresponds
to the principle of least action. That is, the principle of maximum entropy of the equilibrium system in
thermodynamics follows from the key principle of classical mechanics, which is the principle of least
action. This is a key argument in favor of the fact that the second law of thermodynamics should be a
consequence of the laws of mechanics. Based on the mechanics of structured particles, the nature of
the achievement of an equilibrium state by the system is demonstrated. An extension of the canonical
principle of least action for nonequilibrium systems is considered. It is shown how this expansion is
associated with the work of dissipative forces, which tends to zero as soon as the system comes to
equilibrium. When the system reaches equilibrium, the expanded principle of least action is converted
to the canonical principle of least action.