Marcos Rosenbaum

WIGNER METHOD IN QUANTUM STATISTICAL MECHANICS.

The Wigner method of transforming quantum‐mechanical operators into their phase‐space analogs is reviewed with applications to scattering theory, as well as to descriptions of the equilibrium and dynamical states of many‐particle systems. Inclusion of exchange effects is discussed.

Space–time homogeneous models with torsion

A space‐time homogeneous model is one in which the metric and the connection are invariant under a four‐dimensional transitive Lie group. The Einstein‐Cartan theory describes the effect of spin on geometry. The field equations require a stress‐energy tensor and a spin tensor for a perfect fluid, and we give the required forms here. The main part of this paper is a presentation of several classes of space‐time homogeneous solutions of the Einstein‐Cartan equations for perfect fluid cosmological models.