Thermodynamics

Abstract

A large number of textbooks and articles on thermodynamics, and classical or quantum physics claim that thermodynamics is a statistical theory applicable only to systems consisting of very large numbers of particles in thermodynamic equilibrium states, entropy is defined as a measure of ultimate disorder and not as a physical property of the system, and disorder is defined as representing motions of particles with different velocities both in values and in directions. The purpose of this article is to show and emphasize once more that none of these claims is valid for the following reasons: Thermodynamics is a science that: (i) applies to all systems, regardless of whether they consist of one spin, one particle, or any number of constituents of any kind, and to all states, regardless of whether the state is unsteady, steady, nonequilibrium, different types of equilibrium, or stable (thermodynamic) equilibrium; (ii) entropy is a nonstatistical physical property of any system in any state, in the same sense that energy is a nonstatistical physical property of any system in any state; and (iii) any stable equilibrium state is a state of ultimate order. Similar comments apply to thermodynamics in its quantum form but are not included for the sake of brevity.