Time and thermodynamics extended discussion on “Time & clocks: A thermodynamic approach”

Abstract

In the paper, “Time & clocks: A thermodynamic approach” Lucia and Grisolia describe the connections between the physical nature of time and macroscopic irreversibility in thermodynamics. They also discuss the possibility of constructing a thermodynamic clock that links the two, through an approach based on the behaviour of a black body. Their work primarily focuses on the macroscopic irreversibilty, and their attempt to define ‘thermodynamic time’ is grounded on the concepts from non-equilibrium thermodynamics such as, entropy generation and time-dependent thermodynamic fluxes - in and out of the system. In this letter, we present a first principles approach based on the Maupertuis principle to describe the connection between time and thermodynamics for equilibrium phenomena. Our novel interpretation of the temperature as a functional allows us to extend our formalism to irreversible processes when the local equilibrium hypothesis is satisfied. Through our framework we also establish a functional relationship between equilibrium and non-equilibrium time-scales while distinguishing between the two.