The first few years of RHIC operations produced many spectacular and unexpected results that turned out to be qualitatively very different from earlier expectations. This triggered an unusually high amount of new theoretical activities, and many new concepts were put forward to explain the observed phenomena. As the experiments mature, data sets become larger and analysis techniques improve, we are entering an era where the results become sufficiently accurate to confirm or reject theories and put quantitative limits on the free parameters of the viable ones. Based on measurements of electromagnetic probes in PHENIX we will report on the first steps already taken on this long road. We will also discuss how detector upgrades, to be installed in the near future and the increased luminosity of RHIC-II will help to improve the precision of our measurements and, as a consequence, improve our understanding of the properties and dynamics of the hot, dense matter created in relativistic heavy ion collisions as well of the phase transition itself in which it is formed.