Challenges in Thermodynamics: Irreversible Processes, Nonextensive Entropies, And Systems Without Equilibrium States (Report‪)‬

OPENING REMARKS Irreversible pathways connecting two equilibrium states are not well understood. Even less is known about general rules which govern systems far from equilibrium. In this mini-review, I have made a choice of some problems which, in my opinion, define challenges facing our community of thermo dynamics and statistical mechanics. Among them I will present the Jarzynski equation, discovered in 1997, which relates works done in irreversible processes to the free energy difference [1-5]. Furthermore, I will describe recent findings concerning dynamic pathways governing evaporation and condensation [6-19] and mention late stages of a process of phase separation [20]. I will also discuss systems that are nonextensive and therefore cannot be described by the Boltzmann-Gibbs-Shannon (BGS) entropy. In its place, new paradigms are introduced such as Renyi or Tsallis entropies [21-26]. Finally, I will briefly touch on the problem of systems, such as living matter, which by definition do not have equilibrium states. We cannot use, in their context, a paradigm of isolated system or equilibrium state or even a notion of subsystem. Most certainly, new descriptions and new paradigms are needed to properly describe such systems.