

Abstract for the talk on 26.06.2018 (17:00 h)
Colloquium of the Faculty of Physics and GeosciencesLamberto Rondoni (Università di Torino)
Irreversibility: from Rarefied Gases to the Expanding Universe
We review an approach to macroscopic irreversibility from microscopic time reversal
invariant dynamics, that can be traced back to Boltzmann; an approach that rests on the
special initial conditions of the universe, and on its expansion. We discuss the notion of
entropy as a measure of disorder, and how the (irreversible) Boltzmann equation can be
harmonized with the (reversible) dynamics of classical particles. This way we illustrate
Boltzmann's reply to the macroscopically pardoxical but dynamically justified observations
on his theory, due to Loschmidt and Zermelo. We finally discuss possible advances with
respect to this approach, highlighting points in which it may be reviewed, from both a
mathematical and a physical standpoint, drawing from recent results on time reversibility
in presence of magnetic fields, and on consequences of the so-called fluctuation theorems.