For many years the photograph of those who gathered in Brussels in October 1927 for the fifth Solvay conference hung on my wall. Occasionally I would pass it and think that it was the perfect starting point for a narrative history of the quantum. When I finally wrote a proposal for Quantum, I had the great good fortune of submitting it to Patrick Walsh. His enthusiasm was instrumental in getting the project off the ground. I was lucky a second time when the talented science editor and publisher Peter Tallack joined Conville & Walsh and became my agent. To Pete I offer my heartfelt thanks for being both friend and agent through the years that this book took to write and for handling with grace all the difficulties that arose from my prolonged bouts of ill-health. Together with Pete, Jake Smith-Bosanquet has served as my point man for the foreign language publishers of Quantum; I would like to express my thanks to him and the rest of the team at Conville & Walsh, particularly Claire Conville and Sue Armstrong, for their steadfast support and help. It is a pleasure to have this opportunity to thank Michael Carlisle and especially Emma Parry for their work on my behalf in the USA.
I owe a great deal to the studies of scholars cited in the notes and listed in the bibliography; however, I am particularly indebted to Denis Brian, David C. Cassidy, Albrecht Fölsing, John L. Heilbron, Martin J. Klein, Jagdish Mehra, Walter Moore, Dennis Overbye, Abraham Pais, Helmut Rechenberg, and John Stachel. I would like to thank Guido Bacciagaluppi and Anthony Valentini for making available the first English-language translation of the proceedings of the fifth Solvay conference and their commentary prior to its publication.
Pandora Kay-Kreizman, Ravi Bali, Steven Böhm, Jo Cambridge, Bob Cormican, John Gillott, and Eve Kay all read drafts of the book. Thanks go to each and every one of them for their astute criticism and suggestions. Mitzi Angel was at one time my editor and her insightful comments on an earlier draft of the book were invaluable. Christopher Potter was an early champion of Quantum and I am deeply grateful to him for having been so. Simon Flynn, my publisher at Icon Books, has been indefatigable in bringing the book to press. He has done much that was beyond the call of duty and I thank him for it. Duncan Heath has been an astonishingly eagle-eyed copy-editor; every writer should be so fortunate. I am grateful to Andrew Furlow and Najma Finlay of Icon for their enthusiasm and work on behalf of Quantum and to Nicholas Halliday for producing the fine diagrams that illustrate the text. Thanks also go to Neal Price and his team at Faber & Faber.
This book would not have been possible without the unfailing support over many years of Lahmber Ram, Gurmit Kaur, Rodney Kay-Kreizman, Leonora Kay-Kreizman, Rajinder Kumar, Santosh Morgan, Eve Kay, John Gillott, and Ravi Bali.
Finally, I wish to thank, with all my heart, my wife Pandora and my sons Ravinder and Jasvinder. Words are not enough to convey what I owe to the three of you.