Physics of thermalization and level density in an isolated system of strongly interacting particles

Here, we present a short review of ideas, methods and results for understanding the evolution of an excited mesoscopic system of strongly interacting constituents. We discuss the process of thermalization with its characteristic time dependence different from what is known in classical mechanics, the resulting state of quantum chaos, enhancement of sensitivity to weak perturbations including violation of fundamental symmetries in nuclei, problem of the level density, and effects of continuum and superradiance