High energy photons and lepton pairs are created by the interactions of quarks and gluons during the first, few fm c of a nucleus-nucleus collision when the energy density is the greatest. Advances ill the calculation of these electromagnetic signals are discussed. In particular, the parton cascade model allows us to compute Drell-Yan, pre-equilibrium, and equilibrium emission within a single dynamical framework.
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I would like to thank my colleague and friend Klaus Geiger for assistance in preparing this talk. This work was supported by the U. S. Department of Energy under grant DOE/DE-FG02-S7ER-40:325.