The work of the Austin-Brussels group on the microscopic origin of irreversibility is described. Using extensions of the traditional Hilbert space and Poincaré's nonintegrability, we obtain new formulations of laws of dynamics which can be expressed only in terms of probabilities (and not in...

Simple mechanisms through which nonequilibrium structures can be influenced by external fields are discussed. It is shown that a very weak gravitational or electric field can have a large influence on selection or creation of structures. In the absence of cooperativity, the influence of a weak...

A two-level system interacting with the radiation field is considered. The time-dependent self-dressing of its bare ground state is studied. The time evolution of the system is discussed within the theory of subdynamics. Investigation of the long-time behaviour is the main point of this paper....