Heavy ion collisions and black hole dynamics

Relativistic heavy ion collisions create a strongly coupled quark-gluon plasma. Some of the plasma's properties can be approximately understood in terms of a dual black hole. These properties include shear viscosity, thermalization time, and drag force on heavy quarks. They are hard to calculate from first principles in QCD. Extracting predictions about quark-gluon plasmas from dual black holes mostly involves solving Einstein's equations and classical string equations of motion. AdS/CFT provides a translation from gravitational calculations to gauge theory predictions. The gauge theory to which the predictions apply is N = 4 super-Yang-Mills theory. QCD is different in many respects from super-Yang-Mills, but it seems that its high temperature properties are similar enough for us to make some meaningful comparisons.