| Abstract: | The influence of the electromagnetic interaction upon particle creation in expanding Robertson-Walker universes is investigated applying an S-matrix scheme. We discuss all processes contributing to the number density of created particles up to second order in the coupling constant. One process is of particular importance being the only source of photons. It is considered in more detail and evaluated explicitly for a time-symmetrically expanding radiation-dominated Friedman universe as well as statically bounded expansions. |
