  The goal of these notes is to introduce, in a very elementary way, the idea
of the anti de-Sitter/Conformal Field Theory (AdS/CFT) correspondence to
condensed matter physicists. This theory relates a gravity theory in a (d+1)-
dimensional anti-de Sitter spacetime to a strongly-coupled d- dimensional
quantum field theory living on its boundary. The AdS/CFT correspondence can be
used to study finite temperature real time processes, such as response
functions and dynamics far from equilibrium in quantum critical points in
condensed matter systems. Computation of these quantities is reduced to solving
classical gravitational equations in one higher dimension than the original
theory.
