  We calculate the two-body correlation function of direct photons produced in
Au+Au collisions at the Relativistic Heavy Ion Collider. Our calculation
includes contributions from the early pre-equilibrium phase in which photons
are produced via hard parton scatterings as well as radiation of photons from a
thermalized Quark-Gluon-Plasma (QGP) and the subsequent expanding hadron gas.
We find that high energy photon intensity interferometry provides a faithful
probe of the details of the space-time evolution and of the early reaction
stages of the system.
