Leopold Halpern and the generalization of general relativity

Leopold Halpern, who was a close associate of both Erwin Schroedinger and Paul Dirac before making his own mark as a theoretical physicist of the first rank, died in Tallahassee, Florida on 3 June 2006 after a valiant struggle with cancer. We give an outline of his life and work, including his progress towards a unified gauge theory of gravitation and spin.