Initial Energy Density, Momentum and Flow in Heavy Ion Collisions

The very early phase of the collision of large nuclei at high energies is described by the color glass condensate. We compute the energy and momentum densities of the gluon field in a classical approximation at the earlierst stage of the collision. We also present constraints for the initial energy density, pressure and flow in the subsequent plasma phase. Phenomenological consequences for RHIC and LHC are discussed.