  I review arguments for the existence of a critical point E in the QCD phase
diagram as a function of temperature T and baryon chemical potential \mu. I
describe how heavy ion collision experiments at the SPS and RHIC can discover
the tell-tale signatures of such a critical point, thus mapping this region of
the QCD phase diagram. I contrast the different ways in which the matter
produced in a heavy ion collision can be driven out of equilibrium: quenching
out of equilibrium (possible, but not guaranteed, if the transition region is
traversed at \mu << \mu_E) vs. slowing out of equilibrium (guaranteed for \mu
\sim \mu_E) vs. bubbling out of equilibrium (possible, but not guaranteed, for
\mu >> \mu_E). Quenching or bubbling create and amplify distinct, detectable,
non-gaussian fluctuations. In contrast, slowing out of equilibrium reduces the
magnitude of the specific, detectable, gaussian fluctuations which signal the
presence of the critical point.
