Physics at Extreme Temperatures and Energy Densities

The study of the fundamental theory of strong interactions, QCD, in extreme conditions of temperature and energy density has attracted large experimental and theoretical interest. Experimental and theoretical studies of collective behavior of QCD are being pursued at the accelerators colliding ultra-relativistic heavy nuclei. The last few years have seen many unexpected and exciting results which are revolutionizing our understanding of matter under these conditions. In this talk I will discuss the latest physics from RHIC and the plans for the LHC.