  Highly compressed nuclear matter created in relativistic heavy collisions is
to large extent governed by local non-equilibrium. As an idealised scenario
colliding nuclear matter configurations are studied with an effective in-medium
interaction based on the microscopic DBHF model. It is found that on top of the
repulsive momentum dependence of the nuclear forces kinetic non-equilibrium
leads to an effective softening of the equation of state as compared to ground
state nuclear matter. The separation of phase space which is the basic feature
of such anisotropic configurations has thereby a similar influence as the
introduction of a virtual new degree of freedom.
