Thomas Gilbert email: thomas_dot_gilbert_at_ulb_dot_ac_dot_be
Physics of Complex Systems and Statistical Mechanics
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My work focuses on the dynamical aspects of time asymmetric processes in nonequilibrium statistical mechanics.

Systems out of equilibrium are characterized by currents driven by thermodynamic forces. These forces are due to the presence of gradients, such as when the two ends of a copper bar are in contact with thermal baths at different temperatures. Thermodynamics expresses the resulting heat flux in terms of the temperature gradient. This macroscopic law is deterministic and can, at least in principle, be formulated in terms of the interactions of the many atoms which constitute the system and its environment. Such a Newtonian description of the system at the microscopic level is also deterministic, yet, contrary to its macroscopic counterpart which is irreversible, it is symmetric under time reversal. The breaking of this time symmetry is one of the great puzzles of non-equilibrium statistical mechanics. Its resolution involves the identification of a proper rescaling procedure which typically yields an intermediate mesoscopic level of description where the evolution is of stochastic nature.

I am specifically interested in systems of many hard spheres which are let to interact only rarely. This happens for instance when gas particles are spatially confined to nanoscale cells, or nanopores. Such models were origininally devised by L A Bunimovich and co-workers in the context of ergodic theory. With P Gaspard, we showed their heat conductivity can be computed from first principles in terms of the frequency of collision between particles in neighboring nanopores. This generic property amounts to a derivation of the macrosopic properties of such systems from scratch.

See the talk A two-stage approach to relaxation in locally confined hard sphere systems given at the Fields Institute (Toronto) on April 5, 2011 as part of the Workshop on the Fourier Law and Related Topics.