Gibbs Entropy and Irreversibility

This contribution is dedicated to dilucidating the role of the Gibbs entropy in the discussion of the emergence of irreversibility in the macroscopic world from the microscopic level. By using an extension of the Onsager theory to the phase space we obtain a generalization of the Liouville equation describing the evolution of the distribution vector in the form of a master equation. This formalism leads in a natural way to the breaking of the BBGKY hierarchy. As a particular case we derive the Boltzmann equation

The non-equilibrium work relation. Thermodynamic analysis and microscopic foundations

We discuss the conditions for which the non-equilibrium work relation is valid by means of thermodynamic and microscopic arguments.Comment: 16 pages 1 figur

Quantum Theory of Irreversibility

A generalization of the Gibbs-von Neumann relative entropy is proposed based on the quantum BBGKY [Bogolyubov-Born-Green-Kirkwood-Yvon] hierarchy as the nonequilibrium entropy for an N-body system. By using a generalization of the Liouville-von Neumann equation describing the evolution of a density super- operator, it is demonstrated that the entropy production for an isolated system is non-negative, which provides an arrow of time. Moreover, following the procedure of non-equilibrium thermodynamics a master matrix is introduced for which a mi- croscopic expression is obtained. Then, the quantum Boltzmann equation is derived in terms of a transition superoperator related to that master matrix

Llibertat, igualtat i laïcitat en l’àmbit educatiu

Els atemptats de l’11-S de 2001 als Estats Units, a Bali el 2002, a Madrid el 2003, i a Londres el 2005 –entre d’altres factors– han provocat que la religió estigui més present a les agendes polítiques, socials i culturals dels països d’arreu del món, malgrat les declaracions reiterades que rebutgen una identificació a priori entre terrorisme i religió. Religió i seguretat conformen, doncs, un nou binomi, un nou enfocament per a la promoció dels drets humans i per a la prevenció de la pau internacional. I l’ensenyament n’ha de ser una de les peces clau

Mesoscopic non-equilibrium thermodynamics approach to the dynamics of polymers

We present a general formalism able to derive the kinetic equations of polymer dynamics. It is based on the application of nonequilibrium thermodynamics to analyze the irreversible processes taking place in the conformational space of the macromolecules. The Smoluchowski equation results from the analysis of the underlying diffusion process in that space within the scheme of nonequilibrium thermodynamics. We apply the method to different situations, concerning flexible, semiflexible and rod-like polymers and to the case of more concentrated solutions in which interactions become important.Comment: 13 pages (RevTex). To be published in Physica