From 23 July to 10 August 1977 a group of 125 physicists from 72 laboratories of 20 countries met in Erice to attend the 15th Course of the International School of Subnuclear Physics. The countries represented at the School were: Belgium, Bulgaria, Denmark, Federal Republic of Germany, Finland, France, Hungary, Ireland, Israel, Italy, Japan, the Netherlands, Norway, Poland, Sweden, Switzerland, the United Kingdom, the United States of America and Venezuela. The School was sponsored by the Italian Ministry of Public Education (MPI), the Italian Ministry of Scientific and Technologi cal Research (MRST) , the North Atlantic Treaty Organization (NATO), the Regional Sicilian Government (ERS) and the Heizmann Institute of Science. The School was very exciting due to the impressive number of frontier problems which were discussed. Being the 15th year of the School, it was decided to review all outstanding "Whys". At various stages of my work I have enjoyed the collaboration of many friends whose contributions have been extremely important for the School and are highly appreciated. I would like to thank Dr.A. Gabriele, Ms.S. McGarry, Mr. and Mrs. S. Newman, Ms.P. Savalli and Ms.M. Zaini for the general scientific and administrative work. Finally, I would like to thank most warmly all those ~n Erice, Bologna and Geneva who helped me on so many occasions and to whom I feel very much indebted.

For almost two decades, Sidney Coleman has been giving review lectures on frontier topics in theoretical high-energy physics at the International School of Subnuclear Physics held each year at Erice, Sicily. This volume is a collection of some of the best of these lectures. To this day they have few rivals for clarity of exposition and depth of insight. Although very popular when first published, many of the lectures have been difficult to obtain recently. Graduate students and professionals in high-energy physics will welcome this collection by a master of the field.

For the Galvani Bicentenary Celebrations, the University of Bologna and its Academy of Sciences singled out subnuclear physics as the field of scientific research to be associated with this important event, as it would best illustrate, for the new generation of students, the challenge inherent in fundamental sciences. Subnuclear physics has represented, ever since it was born, the new frontiers of Galilean science. In his opening lecture delivered on the first day of the new academic year, Professor Antonino Zichichi analytically reviewed the basic conceptual developments and main discoveries achieved in subnuclear physics since its birth in the 20th century. Given the importance of this field of fundamental research, Professor Zichichi was invited to expand the contents of his lecture into a book, and the outcome is this volume.

This volume is a collection of lectures given by distinguished physicists from around the world, covering the most recent advances in theoretical physics and the latest results from current experimental facilities.Following one of the principal aims of the School ? to encourage and promote young physicists to achieve recognition at an international level ? the students who distinguished themselves for the excellence of their research were given the opportunity to publish their presentations in this volume.

This volume is a collection of lectures given during the 42nd Course of the International School of Subnuclear Physics. The contributions cover the most recent advances in theoretical physics and the latest results from current experimental facilities. In line with one of the aims of the school, which is to encourage and promote young physicists to achieve recognition at an international level, the studentsOCO recognized for their research excellence were given the opportunity to publish their work in this volume. Their contributions are joined by those from many distinguished lecturers in the field from around the world."

In August 1978 a group of 80 physicists from 51 laboratories of 15 countries met in Erice to attend the 16th Course of the International School of Subnuclear Physics. The countries represented at the School were: Austria, Denmark, Federal Republic of Germany, Finland, France, Israel, Italy, the Netherlands, Sweden, Switzerland, South Africa, Turkey, the United Kingdom, The United States of America, and Yugoslavia. The School was sponsored by the Italian Ministry of Public Education (MPI) , the Italian Ministry of Scientific and Technological Research (MRSI) , the North Atlantic Treaty Organization (NATO), the Sicilian Regional Government, and the Weizmann Institute of Science. As usual, the Course was devoted to a review of the most out standing problems and results in Subnuclear Physics, with particular emphasis on the new aspects; there were mainly two: supersymmetry and electroweak interactions. In his famous lecture at Erice in 1967, Sid Coleman reviewed "All possible symmetries of the S matrix. " All but one, namely that which tells you: if you have a fermion you must have a boson. This is super symmetry , and this produces the superspace, i. e. an entity which has not only the Einstein-"bosonic" coordinates, but also "fermionic" coordinates. From superspace we get supergravity; and this means that one day we should be able to detect not only the graviton (with spin 2) but also the gravitino (spin 3/2). If we add "flavour", "colour", and "family" as other intrinsic degrees of freedom, we get extended supergravity.