Abstract This book is the result of the International Conference on Advances in Pilot Wave Theory, hosted by the Centre for Philosophy of Sciences of the University of Lisbon (CFCUL), Portugal, held from 26 to 30 July 2021 (International Conference on Advances in Pilot Wave Theory—Concurrently Hosting Hydrodynamic Quantum Analogs HQA-2021 n.d.; Advances in Pilot Wave Theory & HQA2021—YouTube n.d.). The conference concurrently hosted the Hydrodynamic Quantum Analogs meeting (HQA-2021) owing to the common interests of these seemingly disparate fields. The meeting took place online due to the COVID Pandemic lockdown and attracted participants from distant points of the globe, including the United States, Canada, Brazil, Mexico, Portugal, the United Kingdom, Italy, France, the Netherlands, Germany, Russia, Australia, and Israel.
We reconsider the crucial 1927 Solvay conference in the context of current research in the foundations of quantum theory. Contrary to folklore, the interpretation question was not settled at this conference and no consensus was reached; instead, a range of sharply conflicting views were presented and extensively discussed. Today, there is no longer an established or dominant interpretation of quantum theory, so it is important to re-evaluate the historical sources and keep the interpretation debate open. In this spirit, we provide a complete English translation of the original proceedings (lectures and discussions), and give background essays on the three main interpretations presented: de Broglie's pilot-wave theory, Born and Heisenberg's quantum mechanics, and Schroedinger's wave mechanics. We provide an extensive analysis of the lectures and discussions that took place, in the light of current debates about the meaning of quantum theory. The proceedings contain much unexpected material, including extensive discussions of de Broglie's pilot-wave theory (which de Broglie presented for a many-body system), and a "quantum mechanics" apparently lacking in wave function collapse or fundamental time evolution. We hope that the book will contribute to the ongoing revival of research in quantum foundations, as well as stimulate a reconsideration of the historical development of quantum physics. A more detailed description of the book may be found in the Preface. (Copyright by Cambridge University Press (ISBN: 9780521814218).)