The study of nuclear dynamics is now in one of its most interesting phases. The theory is in the process of establishing an increasingly reliable transport description of heavy ion reactions from the initial violent phase dominated by first collisions to the more thermalized later stages of the reaction. This is true for the low-to-medium energy reactions, where the dynamics is formulated in terms of nucleonic, or in general hadronic, degrees of freedom. And it is also becoming a reality in ultrarelativistic heavy-ion reactions, where partonic elementary degrees of freedom have to be used....