ABSTRACT
Is there a reason for time symmetry breaking at the fundamental level? As the loss of dynamical information due to measurements or approximations is neither a reason nor an explanation, one has to search for the qualitative properties of dynamics which give rise to time asymmetry. Following the pioneering work of Ilya Prigogine and Arno Bohm, one can simply discover the following fact of life: when dynamics (classical or quantum) have resonances due to nonintegrability or instability, there are extensions (of the domain of the evolution operators) of dynamics which are intrinsically irreversible, i.e. the extended evolution group splits into two distinct semigroups. We shall present selected results of the Brussels-Austin-Thessaloniki groups during the last years.
