The clarification of the superselection structure of abelian gauge quantum field theories, such as quantum electrodynamics, is a longstanding problem, where progress has been painfully slow because of notorious infrared problems. In this talk a survey of the present state of affairs is given and results of recent work in progress in collaboration with Sergio Doplicher and John E. Roberts are reported. This new approach is based on the observation that the infrared problems disappear by restricting the Minkowski space theory to any lightcone, i.e. the at best accessible parts of spacetime in real measurements.

Institut für Theoretische Physik, Universität Göttingen