This book collects the lectures given at the NATO Advanced Study Institute on "Atoms in Strong Fields," which took place on the island of Kos, Greece, during the two weeks of October 9-21,1988. The designation "strong field" applies here to an external electromagnetic field that is sufficiently strong to cause highly nonlinear alterations in atomic or molecular struc ture and dynamics. The specific topics treated in this volume fall into two general cater gories, which are those for which strong field effects can be studied in detail in terrestrial laboratories: the dynamics of excited states in static or quasi-static electric and magnetic fields; and the interaction of atoms and molecules with intense laser radiation. In both areas there exist promising opportunities for research of a fundamental nature. An electric field of even a few volts per centimeter can be very strong on the atom ic scale, if it acts upon a weakly bound state. The study of Rydberg states with high reso lution laser spectroscopic techniques has made it possible to follow the transition from weak-field to strong-field behavior in remarkable detail, using static fields of modest lab oratory strength; in the course of this transition the atomic system evolves from one which can be thoroughly understood in terms of field-free quantum numbers, to one which cannot be meaningfully associated at all with the zero-field states of the atom."

This book collects the lectures given at the NATO Advanced Study Institute on "Atoms in Strong Fields," which took place on the island of Kos, Greece, during the two weeks of October 9-21,1988. The designation "strong field" applies here to an external electromagnetic field that is sufficiently strong to cause highly nonlinear alterations in atomic or molecular struc ture and dynamics. The specific topics treated in this volume fall into two general cater gories, which are those for which strong field effects can be studied in detail in terrestrial laboratories: the dynamics of excited states in static or quasi-static electric and magnetic fields; and the interaction of atoms and molecules with intense laser radiation. In both areas there exist promising opportunities for research of a fundamental nature. An electric field of even a few volts per centimeter can be very strong on the atom ic scale, if it acts upon a weakly bound state. The study of Rydberg states with high reso lution laser spectroscopic techniques has made it possible to follow the transition from weak-field to strong-field behavior in remarkable detail, using static fields of modest lab oratory strength; in the course of this transition the atomic system evolves from one which can be thoroughly understood in terms of field-free quantum numbers, to one which cannot be meaningfully associated at all with the zero-field states of the atom."

This volume contains articles from invited speakers at a meeting which took place in Delphi, during the week of October 12-16, 1987. The theme of the meeting was ''The concept of probability" and was organized by the "Group of Interdisciplinary Research" (Physics Department, University of Athens) and the Theoretical and Physical Chemistry Institute of the National Hellenic Research Foundation, Athens. (The Group ofInterdisciplinary Research organized two previous Meetings, 1) on the Concept of physical reality (1982) and 2) on the question of determinism in Physics (1984". This small gathering, which was attended by scientists, mathematicians and philosophers from more than 22 countries, took place on the occasion of the 100th year from the birthday of E.Schrodinger. As the father of wave-mechanics, Schrodinger thrushed us into an era of physics where knowledge of the lV-function is considered, for most situations, as the ultimate aim and the ultimate truth. Yet, he, as well as another towering figure of 20th century physics, A.Einstein, never really felt confortable with the interpretation of the meaning oflV and of the information that it contains. With Einstein playing the leading role a debate about concepts and interpretation started as soon as quantum mechanics was born. Central theme to this debate is the concept of probability, a concept which permeates-explicitly or implicitly-all science and even our decision making in everyday life. The articles cover a broad spectrum of thought and results -mathematical, physical, epistemological, experimental, specific, general,-many of them outside the accepted norm.