Fundamental Theories of Physics An International Book Series on The Fundamental Theories of Physics: Their Clarification,Development and Application Editor: ALWYN VAN DER MERWE,University of Denver,U.S.A. Editorial Advisory Board: JAMES T.CUSHING,University of Notre Dame,U.S.A. GIANCARLO GHIRARDI,University of Trieste,Italy LAWRENCE P.HORWITZ,Tel-Aviv University,Israel BRIAN D.JOSEPHSON,University of Cambridge,U.K. CLIVE KILMISTER,University of London,U.K. PEKKA J.LAHTI,University of Turku,Finland ASHER PERES,Israel Institute of Technology,Israel EDUARD PRUGOVECKI,University of Toronto,Canada TONY SUDBURY,University of York,U.K. HANS-JURGEN TREDER,Zentralinstitut fuir Astrophysik der Akademie der Wissenschaften,Germany Volume 146Fundamental Theories of Physics An International Book Series on The Fundamental Theories of Physics: Their Clarification, Development and Application Editor: ALWYN VAN DER MERWE, University of Denver, U.S.A. Editorial Advisory Board: JAMES T. CUSHING, University of Notre Dame, U.S.A. GIANCARLO GHIRARDI, University of Trieste, Italy LAWRENCE P. HORWITZ, Tel-Aviv University, Israel BRIAN D. JOSEPHSON, University of Cambridge, U.K. CLIVE KILMISTER, University of London, U.K. PEKKA J. LAHTI, University of Turku, Finland ASHER PERES, Israel Institute of Technology, Israel EDUARD PRUGOVECKI, University of Toronto, Canada TONY SUDBURY, University of York, U.K. HANS-JÜRGEN TREDER, Zentralinstitut für Astrophysik der Akademie der Wissenschaften, Germany Volume 146