The short Heroic Age of physics that started in 1925 was one of the rare occasions when a deep consideration of the question: What does physics really say? was necessary in carrying out numerical calculations. In many parts of microphysics the calculations have now become relatively straightforward if not easy, but most physicists seem to agree that some questions of principle remain to be resolved, even if they do not think it is very important to do so. This situation has affected the way people think and write about quantum mechanics, a gingerly approach to fundamentals and a tendency to emphasize what fifty years ago was new in the new theory at the expense of continuity with what came before it. Nowadays those who look into the subject are more likely to be struck by unexpected similarities between quantum and classical mechanics than by dramatic contrasts they had been led to expect. It is often said that the hardest part of understanding quantum mechanics is to understand that there is nothing to understand; all the same, to think quantum mechanically it helps to have firm mental connections with classical physics and to know exactly what these connections do and do not imply. This book originated more than a decade ago as informal lecture notes [OP, prepared for use in a course taught from time to time to advanced undergraduates at Williams College.

Mechanics: Classical and Quantum is a 13-chapter book that begins by explaining the Lagrangian and Hamiltonian formulation of mechanics. The Hamilton-Jacobi theory, historical background of the quantum theory, and wave mechanics are then described. Subsequent chapters discuss the time-independent Schrödinger equation and some of its applications; the operators, observables, and the quantization of a physical system; the significance of expectation values; and the concept of measurement in quantum mechanics. The matrix mechanics and the "hydrogenic atom", an atom in which one electron moves under the influence of a nucleus of charge that, to a very good approximation, can be thought of as a point, are also presented. This book will be very useful to students studying this field of interest.

Geared toward upper-level undergraduates and graduate students, this self-contained first course in quantum mechanics covers basic theory and selected applications and includes numerous problems of varying difficulty. 1992 edition.

Since 1972 the Schools on Nonlinear Physics in Gorky have been a meeting place for Soviet Scientists working in this field. Since 1989 the proceedings appear in English. They present a good cross section of nonlinear physics in the USSR. This third volume emerged from material presented at the 1989 School. It contains sections dealing with nonlinear problems in physics and astrophysics, quantum and solid state physics, dynamical chaos and self-organization.