ABSTRACT
The so-called Gallavotti-Cohen Fluctuation Relation (FR) has been put forward for the first time in (Evans et al. 1993). The FR is a theorem (Gallavotti & Cohen 1995) proved for (a) chaotic dynamical systems with microscopic reversibility, when the entropy production (identified with the phase space contraction rate) is measured, and (b) for Markov processes (Kurchan 1998; Lebowitz & Spohn 1999) when the fluctuations of a suitably defined function of the phase space trajectories, taken as a measure of violation of the detailed balance, i.e. of entropy production, are measured. In essence, FR states that, στ being the measured fluctuating quantity integrated over a time τ and f (στ) its probability density function,
when τ → ∞.
