PHYSICS AND ASTRONOMY COLLOQUIUM

Thursday, February 15, 2007
4:10 p.m.

1415 Biomedical & Physical Sciences Bldg.

Refreshments at 3:30 pm in Rm. 1400 BPS Bldg


Speaker: E.G.D. Cohen
         Rockfeller University

Title:   Stationary States and Their Fluctuations

Abstract:

The simplest stationary state is the thermal equilibrium state and the
fluctuations around them have been treated by Onsager’s Regression
Hypothesis. A number of consequences of this Hypothesis will be
mentioned, amongst which is the construction of a purely macroscopic
theory of irreversible processes near equilibrium, based on local
equilibrium: where Hydrodynamics and Irreversible Thermodynamics hold.
The equations which describe hydrodynamic fluctuations will be given.

Far from equilibrium a phase space distribution function has been
developed for chaotic systems: The Sinai-Ruelle-Bowen (SRB)
distribution, which will be briefly explained.

Fluctuations far from equilibrium have been studied via a Stationary
State Fluctuation Theorem, which is an extension of the Second Law of
Thermodynamics and has led to experiments which agree with the Theorem.