GSI Helmholtzzentrum Darmstadt, GERMANY
Heavy-ion collisions provide the only means to explore densities different from the saturation density, $\rho_0$, as in the course of such a collision matter suffers compression and expansion phases. In the energy range accessible to the SIS accelerator (0.1-1.5AGeV) at GSI nuclear matter is compressed up to 3 $\rho_0$. A multitude of observables have been studied --- as a follow-up of the pioneering work done at the heavy ion accelerator at Berkeley in the eighties and early nineties --- by various experiment at GSI. The SIS energy regime has been systematically studied with the FOPI detector for various system sizes and a rather complete observable data base spanning large energy ranges in sufficiently small steps has been collected in the previous years and has been confronted with the prediction of microscopic transport theories. \\ Microscopic transport theories are necessary to access the properties of the nuclear equation of state from heavy-ion reaction data that relaxes the local equilibrium assumption. Such dynamical theories have been developed and are continuously being improved. The FOPI data collected in the SIS energy region will be presented and the current status of constraining the bulk properties of nuclear matter will be discussed. \\ Even more extreme conditions will be created in heavy-ion collisions of stable and radioactive beams at the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt. Here, the goal of the experiments is to explore the phase diagram of nuclear matter in the region of the highest baryon densities and large isospin-asymmetries. The future heavy-ion program at FAIR will be discussed.