title: Irreversibility time scale.
abstract: Entropy creation rate is introduced for a system interacting with thermostats (i.e., for a system subject to internal conservative forces interacting with "external" thermostats via conservative forces) and a fluctuation theorem for it is proved. As an application, a time scale is introduced, to be interpreted as the time over which irreversibility becomes manifest in a process leading from an initial to a final stationary state of a mechanical system in a general nonequilibrium context. The time scale is evaluated in a few examples, including the classical Joule-Thompson process (gas expansion in a vacuum).
authors.affiliation: Dipartimento di Fisica, I.N.F.N.-Sezione di Roma, 00185 Roma, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Gallavotti