A Story Without an Ending: The Quantum Physics Controversy 1950–1970

Olival Freire, Guido Bacciagaluppi, Olivier Darrigol +4 more

Quantum mechanics approaches its centenary with an impressive record. It became the backbone of most research in physics, led to applications such as the transistor and laser, and prompted an upheaval in the philosophy of science. Its scope and its precision have been constantly growing, and it is now promising more powerful computers and safer cryptography. This century of conquests has also been a time of ongoing debates about the foundations and interpretation of the theory, which has been referred to as the quantum controversy. The controversy has been unusually long and remains open. Jammer called it “a story without an ending” and Laloë described this coexistence of successes and doubts with the metaphor of the colossus with feet of clay. This Handbook is a survey on this history. Some of the so-called “interpretations” are not interpretations of a fixed formalism, they are different theories, thus it has been a debate about the interpretations and the foundations of quantum mechanics. In this volume, the “history of interpretations” is used for the sake of brevity. The successive parts of the Handbook deal with the scientific and philosophical issues under debate, historical landmarks, places and contexts, historical and philosophical theses, and the proliferation of interpretations. This Handbook may serve those interested in the history of quantum mechanics and those who are engaged with, or attracted by current research on quantum information, as it may give them a flavor of the history that led to or lay the groundwork for the current investigations.

E. U. Condon

Basil J. Hiley

In this paper we revisit the controversy that arose between Paul Dirac and Joe Moyal.Our motivation is provided by the fact that the algebraic aspects of both their approaches are becoming more appreciated as interest in the development of non-commutative geometry's attempt to "geometrise" quantum mechanics grows.Both were seeking to understand the role of non-commutativity, Moyal from a consideration of the differences between classical and quantum statistics, while Dirac was exploring its implications for the dynamics.The disagreement arose essentially over which should be given priority, the dynamics or the statistics.We will provide the background to show that both are essential aspects of the same overall mathematical structure. IntroductionN this paper I want to focus on the controversy that arose between Paul Dirac and Joe Moyal as a consequence of their different proposals for developing a phase space approach to quantum theory.This controversy gets to the heart of the fundamental problems in the description of quantum phenomena.Interestingly Dirac and Moyal were both "outsiders" in the sense that they started out as engineers, more so Moyal because of the way he entered academia, a story beautifully told in a biography penned by his wife Ann Moyal (2006).! We pick up the story when Moyal was working in the Meteorological branch of the Ministére de |'Air in Paris at the outbreak of World War IJ.In the ensuing chaos, he managed to escape to England and was eventually given a job at the de Havilland Aircraft Company where he became the Assistant Director of the wartime Vibrations Department.After the war Moyal wanted to work in quantum physics when fortunately an opportunity arose for him to enter academia by becoming an assistant lecturer in the Department of Mathematical Physics at Queen's University Belfast.It was there in 1949 that he published his classic paper which is the focus of his disagreement with Dirac.This disagreement involves the question as how best to develop a (p, x,t) phase space formulation for quantum phenomena, the well-recognised difficulty arising from the non-commutativity of the quantum observables for momentum and position.In other words, if we replace the classical variables, (p,x), by operators, or rather 1. See also Moyal (2017).[Ed.]

Banesh Hoffmann

Roshan Raj

To provide a write-up, impressing on the evolutionary track of quantization of physical quantities such as Energy, momentum, and angular momentum. In addition, to question which fundamental quantity is responsible for making these derived quantities quantized.

Benjamin Z. Gal-Or