APPLICATIONS OF PERIODIC ORBIT THEORY TO N-PARTICLE SYSTEMS

In recent years a number of new techniques have become available in no nequilibrium statistical mechanics, all derived From dynamical system theory, especially From the thermodynamic formalism of Ruelle. We focu s here on periodic orbit theory, and we compare it with a novel approa ch proposed by Evans, Cohen, and Morriss, and developed further by Gal lavotti and Cohen. We argue that the two approaches based on such theo ries are equivalent for systems of many particles if the underlying dy namics is similar to that of Anosov systems, and that such equivalence should remain in more general situations. We extend our previous expl anation of irreversibility in the thermostatted Lorentz gas to !V-part icle diffusion and shearing systems.