  In these lectures aspects of current theory used to interpret the preliminary
data on ultra-relativistic nuclear collisions at RHIC energies in terms of the
physical properties of QCD matter at extreme densities are introduced. Topics
include: What are the physics questions at SPS and RHIC?, Geometrical vs
Dynamical features of A+A, The interplay of computable Hard pQCD vs
phenomenological Soft dynamics, Baryon number transport and Junctions, How can
we compute and get experimental control over the initial conditions?, How to
reconcile apparent hydrodynamic behavior with partonic/hadronic transport
theory. I use the Preliminary RHIC data available up to June 1,2001 to
illustrate these topics. Since the main new observable at RHIC relative to SPS
is jet quenching, I elaborate on this ``tomographic'' probe of ultra-dense
matter. The possible discovery of jet quenching at RHIC by STAR and PHENIX is
highlighted.
