1986 Von Hippel Lecture: The Many-Body Approach to Materials Science

Abstract

I would like to express my gratitude to the Awards Committee and its chairman for bringing me here today. One of the effects, and not the least, of this award is to call on my earliest recollections from the United States. In the Fall of 1956, I arrived in Boston at the Massachusetts Institute of Technology (MIT) as a postdoctoral fellow in the laboratory of Prof. von Hippel. My stay in the Materials Research Laboratory of MIT was a determining influence in my future work.The many-body problem is the study of the effects of interaction between bodies on the behavior of a many-body system. The importance of the many-body problem derives from the fact that almost any real physical system is composed of a set of interacting particles. Another essential aspect is that the many-body problem is not a branch of solid-state or atomic or nuclear physics but deals with general methods applicable to all many-body systems.Because of the complexity of the many-body problem, one of the preferred solutions is simply to ignore it. One can always say, “Let us admit that the particles forming the system do not interact or that their interaction is so weak that the effect can be considered negligible.” In many cases, this method produced good results, and one of the great mysteries is why.