This is the second of two volumes on the genesis of quantum mechanics in the first quarter of the 20th century. It covers the period 1923-1927. After covering some of the difficulties the old quantum theory had run into by the early 1920s as well as the discovery of the exclusion principle and electron spin, it traces the emergence of two forms of the new quantum mechanics, matrix mechanics and wave mechanics, in the years 1923-27. It then shows how the new theory took care of some of the failures of the old theory and put its successes on a more solid basis. Finally, it shows how in 1927 the two forms of the new theory were unified, first through statistical transformation theory, then through the Hilbert space formalism.

This volume provides a detailed analysis of the classic papers by Heisenberg, Born, Jordan, Dirac, De Broglie, Einstein, Schrödinger, von Neumann and other authors. Drawing on the correspondence of these and other physicists, their later reminiscences and the extensive secondary literature on the “quantum revolution”, this volume places these papers in the context of the discussions out of which modern quantum mechanics emerged. It argues that the genesis of modern quantum mechanics can be seen as the construction of an arch on a scaffold provided by the old quantum theory, discarded once the arch could support itself.

Table of Contents

8 Introduction to Volume

Part Ill Transition to the New Quantum Theory

9 The Exclusion Principle and Electron Spin

10 Dispersion Theory in the Old Quantum Theory

11 Heisenberg's Umdeutung Paper

12 The Consolidation of Matrix Mechanics: Born- Jordan, Dirac and the Three-Man-Paper

13 De Broglie's Matter Waves and Einstein's Quantum Theory of the Ideal Gas

14 Schrodinger and Wave Mechanics

15 Successes and Failures of the Old Quantum Theory Revisited

Part IV The Formalism of Quantum Mechanics and Its Statistical Interpretation

16 Statistical Interpretation of Matrix and Wave Mechanics

17 Von Neumann's Hilbert Space Formalism

18 Conclusion: Arch and Scaffold

Review

"At the top of the scaffold, the arch! In Volume 1, Duncan and Janssen told the intricate story of the long struggles in the first twenty years of the emergence of quantum mechanics. Now, in The Arch, they give a definitive analysis of the climactic and brilliant mid-1920s, with the formulation of matrix and wave mechanics. It is an extraordinary achievement: all future work on this topic starts here." -- Jeremy Butterfield, University of Cambridge"

Duncan and Janssen have done something courageous and even audacious. They have surveyed the sprawling, multi-stranded, twenty-seven year saga of the birth and consolidation of modern quantum mechanics and produced a systematic description of the main conceptual advances, in historical context. I expect it will become a unique reference for interested scientists and historians." -- A. Douglas Stone, Yale University"

The book is rendered suitable for classroom use, albeit at the higher undergraduate or graduate levels." -- Steven French, The British Journal for the History of Science

About the Authors

Anthony Duncan, Emeritus Professor of Physics, University of Pittsburgh, Pennsylvania, USA,Michel Janssen, Professor, Program in the History of Science, Technology, and Medicine, University of Minnesota, Minnesota, USA

Anthony Duncan received his PhD in theoretical elementary particle physics in 1975 from the Massachusetts Institute of Technology, under the supervision of Steven Weinberg. Following postdoctoral and junior faculty positions at the Institute for Advanced Study in Princeton and Columbia University in New York, he joined the faculty of the Department of Physics and Astronomy at the University of Pittsburgh in 1981 as Associate Professor of Physics. He has taught a wide range of courses, both at the undergraduate and graduate level, including courses on the history of modern physics. He is now (since 2015) professor emeritus of Physics at the University of Pittsburgh.

Michel Janssen is a historian of modern physics at the University of Minnesota. He has a Master's in physics from the University of Amsterdam and a PhD in history and philosophy of science from the University of Pittsburgh. Before his current position in Minnesota, he was an editor at the Einstein Papers Project. He co-authored The Genesis of General Relativity (Springer, 2007) and co-edited The Cambridge Companion to Einstein (Cambridge, 2014). More recently he has published a series of papers co-authored with Anthony Duncan on the genesis of quantum mechanics.