This volume includes the papers presented during the high energy session of the first Orbis Scientiae held by the Center for Theo­ retical Studies, University of Miami. The Orbis met from January 7th to 12th, 1974 for the purpose of allowing scientists in various dis­ ciplines to acquaint each other with frontier problems of their respective disciplines. This Orbis Scientiae was the first of a new series of annual gatherings which have replaced the Coral Gables Conferences. These new meetings will include, in addition to physics, the main­ stay of the Coral Gables Conferences, other sciences and will allow scientists in the various disciplines represented to exchange views with each other as well as among them­ selves. The high energy sessions of the Orbis were devoted primarily to fundamental theories which attempt to unify a number of interactions in physics such as the electromagnetic and gravi­ tational forces, the electromagnetic and weak forces, or indeed all of the known interactions. Papers were also invited on other topics of cur­ rent interest in high energy physics and astro­ physics and they form part of this volume. v PREFACE This volume is not subdivided but the first half is devoted to fundamental theories and the second half to other subjects of current interest. The last paper, on stellar evolution, was presented at the Sixth Annual J. Robert Oppenheimer Memorial Prize Ceremonies by the recipient, Professor Edwin E. Salpeter of Cornell University.