has already proven to be very difficult at SPS energies and will continue to be at RHIC.

To avoid misunderstanding, the discovery of the QGP does not mean that its physical properties are now understood. In fact, it only signals the beginning of a long and well focused direction of research. The history of the neutron star discovery offers an instructive analogy. In 1934 Baade and Zwicky proposed the theoretical existence of neutron stars soon after Chadwick discovered free neutrons. Thirty years later in 1967 Hewish and Bell observed the first few pulsars when suitable radio telescopes could finally be constructed. An amusing anecdote is that they actually agonized for a time about whether LGM (little green men) were sending them encrypted messages from the cosmos. T. Gold in 1968 (as $D+Au$ did at RHIC in 2003) put the debate to rest. Gold proposed that radiative energy loss of a magnetized neutron star would cause a predictable spin down. Later precision measurements confirmed this. Seventy years after its proposal, neutron star research still remains a very active experimental and theoretical direction of physics. Current interest has focused on possible [*color field*]{} super-conductivity [@Alford:1999pb] recently predicted in the very high $\mu_B$ 