Experimental collaborations at the Relativistic Heavy Ion Collider (RHIC) have claimed evidence for the formation of a Quark Gluon Plasma (QGP). There are also strong hints that partons in the wavefunctions of colliding nuclei can be described as a Color Glass Condensate (CGC).
We will address here, in context of the experimental data, our theoretical ideas about the CGC and the QGP. The two are related because, in a heavy ion collision, the QGP is formed from the melting of the QGP. How matter thermalizes in high energy QCD is an outstanding problem; we will point to how our understanding of the dynamical properties of quark gluon matter has been enriched by ideas from statistical physics, condensed matter physics and plasma physics. These ideas will be further tested in the near future by experiments at the Large Hadron Collider (LHC).

Brookhaven National Laboratory, NY, Etats-Unis