2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/114893Leopold 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.12 pages, 1 figure. To appear in the proceedings of the Eleventh Marcel Grossmann Meeting on General Relativity, ed. H. Kleinert, R.T. Jantzen and R. Ruffini (World Scientific, Singapore, 2007)General Relativity and Quantum Cosmologytext