Author's Preface The English clergyman, scientist, and political thinker Joseph Priestley, whose experiments inaugurated the modern era of research into photosynthesis, began his memoirs, published in 1806, with the following modest declaration: Having thought it right to leave behind me some account of my friends and benefactors, it is in a manner necessary that I also give an account of myself, and as the like has been done by many persons and for rea- sons which posterity has approved I make no apology for following their example. Let that also serve as preamble to this account of my own first four decades. As one who was present at the launching of the Nuclear Age and the advent of Big Science, which it ushered in, I was closely asso- ciated with many of the seminal figures of the time, and knew many others—among them E. O. Lawrence and J. Robert Oppenheimer, Otto Warburg and James Franck, Arthur H. Compton, Max Delbrück, Harold Urey, Irène Joliot-Curie, Georg von Hevesy, Edwin McMillan, Alfred Hershey, Glenn Seaborg, Linus Pauling, Arthur Kornberg, Melvin Calvin, Robert Mulliken, Emilio Segrè, Luis Alvarez, and Niels Bohr. With the notable exception of Oppenheimer, each of these won a Nobel Prize. They are clearly worth writing about. Moreover, my own experiences in the early application of isotopic tracer methodology to the study of photosynthesis, as well the hitherto unwritten complete story of the discovery of carbon 14, should be of interest to those historians of science who shoulder the burden of provid- ing definitive studies on the impact of the constructive and revolutionary developments in chemistry and biology that came in the wake of the xi xii AUTHOR'S PREFACE atomic bomb blasts at Hiroshima and Nagasaki. I owe this to the record. The story of my life as a musician is the second thread that runs through the pages that follow. Curiously, I became a scientist almost by accident. Indeed, I had been expected to become a musician, and music has always been a happy counterpoint to my scientific work. Among the friends and benefactors of whom I hope to leave some account are many musicians—prominent among them Isaac Stern and Henri Temiauka. The third, sinister strand to my story is the struggle in which I found myself caught up, quite against my will, to defend myself against the assaults of the House Un-American Activities Committee and others who sought to prove on the basis of false evidence, and sometimes of no evidence at all, that I was a spy and a traitor. An account of how this fight was fought, over many painful years, and finally won, seems al- most a civic responsibility. Certainly I must record the devotion to the cause of justice and efforts on my behalf of some of my friends and benefactors, which were crucial in preventing my career as a scientist from being brutally terminated almost at its outset. The source material had to be sorted, organized, and digested from a sprawling mass of documentation—letters, memorabilia, articles, and the like—accumulated over nearly half a century. The task of se- lection was onerous, and much that digressed too far from the main story had to be omitted. Even so, the text in its original form stood in need of tightening up, and I am indebted in this respect to Peter Dreyer, whose editing helped produce a coherent final version, while effecting necessary cuts and emendations. Careful reading of the manu- script by Edwin McMillan and others, including Emilio Segre and Glenn Seaborg, has eliminated a number of errors of fact. Sugges- tions on matters of content and style by James H. Clark, director of the University of California Press, proved most helpful. And the efforts of Peggy Earhart and Laurie Sprecher produced a readable typed copy from the original handwritten manuscript. I also thank Maurice Le- covre for generously providing the photograph of the Viking Mission 14C Life Detector element. Above all, this task would not have been attempted or brought to completion without the steady encourage- ment and support of my wife, Virginia Swanson Kamen, to whom this book is dedicated, and who devoted many long hours to reading and correcting page proofs. .