  We discuss the early evolution of ultrarelativistic heavy-ion collisions
within a multi-fluid dynamical model. In particular, we show that due to the
finite mean-free path of the particles compression shock waves are smeared out
considerably as compared to the one-fluid limit. Also, the maximal energy
density of the baryons is much lower. We discuss the time scale of kinetic
equilibration of the baryons in the central region and its relevance for
directed flow. Finally, thermal emission of direct photons from the fluid of
produced particles is calculated within the three-fluid model and two other
simple expansion models. It is shown that the transverse momentum and rapidity
spectra of photons give clue to the cooling law and the early rapidity
distribution of the photon source.
