Überlichtgeschwindigkeit in extragalaktischen Radioquellen?

After a discussion of the observed phenomena a short account of the very-long-baseline radio interferometry and the redshift controversy is given. The issue of superluminal velocities in the theory of relativity is clarified and a variety of physical models that have been proposed to account for the observed phenomena are discussed. Finally the data of some superluminal sources and their implications are reviewed.