Lamberto Rondoni (Politecnico di Torino): “Does probability turn material? Statistical mechanics questions concerning equilibrium and non-equilibrium ensembles”

Abstract: As pointed out, e.g. by R. Frigg, the foundations of statistical physics, by and large resting on the notion of statistical ensembles, remain in need of clarification. This may not be such a surprise: statistical physics raises probabilities practically to the rank of the material properties of physical objects, such as mass itself, while one may legitimately side with De Finetti, who stated that “probability does not exist”. We will argue that some difficulties in giving ensembles robust foundations, derive from a gap separating probability, dynamics and mass. This observation will lead us to reconsider the role of Hamiltonian models in explaining relaxation to equilibrium. Further, we will contrast necessary with sufficient dynamical conditions, within a response theory suitable to describe open systems, i.e. systems in contact with an outer environment.