  Ever since we have been in the possession of quantum theories without
observers, such as Bohmian mechanics or the Ghirardi-Rimini-Weber (GRW) theory
of spontaneous wave function collapse, a major challenge in the foundations of
quantum mechanics is to devise a relativistic quantum theory without observers.
One of the difficulties is to reconcile nonlocality with relativity. I report
about recent progress in this direction based on the GRW model: A relativistic
version of the model has been devised for the case of N noninteracting (but
entangled) particles. A key ingredient was to focus not on the evolution of the
wave function but rather on the evolution of the matter in space-time as
determined by the wave function.
