Nuclear Shock Waves in Heavy-Ion Collisions

It is shown that nuclear matter is compressed during the encounter of heavy ions. If the relative velocity of the nuclei is larger than the velocity of first sound in nuclear matter (compression sound for isospin $T=0\mathrm{}$), nuclear shock waves occur. They lead to densities which are 3-5 times higher than the nuclear equilibrium density ${\rho }_0$, depending on the energy of the nuclei. The implications of this phenomenon are discussed.