Drawing Theories Apart Drawing Theories Apart The Dispersion of Feynman Diagrams in Postwar Physics david kaiser The University of Chicago Press chicago and london David Kaiser is associate professor in the Program in Science, Technology, and Society and lecturer in the Department of Physics at the Massachusetts Institute of Technology. The University of Chicago Press, Chicago 60637 The University of Chicago Press, Ltd., London C 2005 by The University of Chicago All rights reserved. Published 2005 Printed in the United States of America 14 13 12 11 10 09 08 07 06 05 1 2 3 4 5 isbn: 0-226-42266-6 (cloth) isbn: 0-226-42267-4 (paper) Library of Congress Cataloging-in-Publication Data Kaiser, David. Drawing theories apart : the dispersion of Feynman diagrams in postwar physics / David Kaiser. p. cm. Includes bibliographical references and index. isbn 0-226-42266-6 (alk. paper)—isbn 0-226-42267-4 (pbk. : alk. paper) 1. Feynman diagrams. 2. Physics—United States—History— 20th century. 3. Physics—History—20th century. I. Title. QC794.6.F4K35 2005 530.0973 0904—dc22 2004023335 ∞ The paper used in this publication meets the minimum requirements of the American National Standard for Information Sciences—Permanence of Paper for Printed Library Materials, ansi z39.48-1992. He teaches his theory, not as a body of fact, but as a set of tools, to be used, and which he has actually used in his work. John Clarke Slater describing Percy Bridgman after Bridgman won the Nobel Prize in Physics, 11 January 1947 Contents Preface and Acknowledgments xi Abbreviations xvii Chapter 1 . Introduction: Pedagogy and the Institutions of Theory 1 Richard Feynman and His Diagrams 1 Paper Tools and the Practice of Theory 7 Pedagogy and Postwar Physics 14 Overview: The Two Meanings of Dispersion 16 part i. dispersing the diagrams, 1948–54 Chapter 2. An Introduction in the Poconos 27 Quantum Electrodynamics and the Problem of Infinities 28 Initial Reception and Lingering Confusion 43 Evidence of Dispersion 52 Chapter 3. Freeman Dyson and the Postdoc Cascade 60 The Rise of Postdoctoral Training 61 Dyson as Diagrammatic Ambassador 65 Life and Physics at the Institute for Advanced Study 83 The Postdoc Cascade 93 A Pedagogical Field Theory 108 viii contents Chapter 4. International Dispersion 112 The Diagrams’ Diaspora 112 Feynman Diagrams in Great Britain 115 Feynman Diagrams in Japan 125 Feynman Diagrams in the Soviet Union 149 Tacit and Explicit Knowledges 167 part ii. dispersion in form, use, and meaning Chapter 5. Seeds of Dispersion 173 The Feynman-Dyson Split 175 Perturbative Methods Fail, Feynman Diagrams Flourish 195 Chapter 6. Family Resemblances 208 Kroll’s Perturbative Bookkeepers 209 Marshak’s Meson Markers 220 Climbing Bethe’s Ladder: Feynman Diagrams and the Many-Body Problem 230 Training Theorists for House and Field 244 part iii. feynman diagrams in and out of field theory, 1955–70 Chapter 7. Teaching the Diagrams in an Age of Textbooks 253 The Postwar Age of Textbooks 255 The New Diagrammatic Textbooks 259 Pedagogy and the Pictures’ Place 270 Chapter 8. Doodling toward a New “Theory” 280 Dispersion Relations 282 Crossing to a New Representation 288 From Bookkeepers to Pole Finders: Polology and the Landau Rules 296 Chew the Program Builder: Nuclear Democracy and the Bootstrap 306 Diagrammatic Bootstrapping and the Emergence of New Theories 314 Chapter 9. “Democratic” Diagrams in Berkeley and Princeton 318 Geoffrey Chew: A Scientist’s Politics of Democracy in 1950s America 322 Pedagogical Reforms: “Secret Seminars” and “Wild Merrymaking” 332 The View from Princeton 346 Conditions of Diagrammatic Possibilities 352 contents ix Chapter 10. Paper Tools and the Theorists’ Way of Life 356 Why Did the Diagrams Stick? Inculcation and Reification 359 In Search of the Vanishing Scientific Theory 377 Appendix A. Feynman Diagrams in the Physical Review, 1949–54 389 Appendix B. Feynman Diagrams in Proceedings of the Royal Society, 1950–54 395 Appendix C. Feynman Diagrams in Progress of Theoretical Physics, 1949–54 397 Appendix D. Feynman Diagrams in Sory¯ushi-ron Kenky¯u, 1949–52 402 Appendix E. Feynman Diagrams in Zhurnal eksperimental’noi i teoreticheskoi fiziki, 1952–59 406 Appendix F. Feynman Diagrams in Other Journals, 1950–54 415 Interviews 419 Bibliography 421 Index 461 Preface and Acknowledgments This book is about what theoretical physicists do and how their daily rou- tines shifted in the wake of the Second World War. I focus on the crafting of theoretical tools, techniques, and practices—the everyday labor of theory— to complement the usual treatments in intellectual and conceptual histories. At stake are our assumptions about how theorists have spent their time and structured their activities. Have their primary concerns centered narrowly on the construction and selection of theories, or have they had other goals in mind when taking pencil and paper in hand? How should historians account for their work? If we assume (as usual) that the quest for distinct scientific theories— delimited by the philosophers’ anemic labels T1, T2, T3—and the selection of one best theory have dominated theorists’ work, then we might be inclined to organize our historical analyses around the birth and death of particular theories. Indeed, today we have huge literatures charting the development of Maxwell’s theory of electrodynamics, Einstein’s theories of special and gen- eral relativity, Heisenberg’s matrix mechanics, Schrodinger’s¨ wave mechanics, their union in a theory of quantum mechanics, and so on. Yet as the best of these historical studies have shown, the objects of study in such cases—“special relativity,” say, or “quantum mechanics”—are rarely single or unitary objects at all. Scientific theories are always open to divergent interpretations and uses, even decades after their construction and selection have supposedly been set- tled. Moreover, theoretical physicists have had much more on their plates than just theories. Theirs has been a world littered with calculations—calculations performed with an ever-changing toolbox of techniques. xii preface and acknowledgments These tools and techniques never apply themselves. Apprentice physicists must rehearse using theoretical tools until such calculational skills become sec- ond nature. These skills are rarely transmitted by formal, written instructions alone. Therefore, we must interrogate the wide range of pedagogical means by which students have become working theorists, eventually wielding the tools of theory with ease. Few tools have meant more to theoretical physicists during the past half century than Feynman diagrams, named for the American theorist Richard Feynman. Feynman diagrams provide a rich map for charting larger transfor- mations in the training of theoretical physicists during the decades after World War II. Even when drawing their diagrams in a similar fashion, members of different research groups gave them meaning and put them to work in distinct ways. Physicists carved out a wide variety of uses for the diagrams between the late 1940s and late 1960s. Historians may add one more: the diagrams de- marcate the boundaries between research groups and chart their pedagogical reproduction over time. Much like the diagrams it describes, this book is meant to contribute to con- structive discussions among heterogeneous communities—historians, sociol- ogists,philosophers,andphysicists.Withthesediversegroupsinmind,mygoal has been to supply specialists with sufficient technical detail to demonstrate my arguments without overwhelming readers from broader backgrounds. To- ward this end, the first and last sections of the book are meant to be broadly accessible, while most of the technical details appear in chapters 5, 6, and 8. Even in these chapters, I have attempted to provide guideposts for readers who last saw an integral sign in high school (and didn’t like it then). *** I have incurred a great many debts while working on this study. This book grew out of my doctoral dissertation in the Department of the History of Science at Harvard University, and it is a pleasure to thank my advisers, Peter Galison, Silvan S. Schweber, and Mario Biagioli, for untiring advice, encouragement, and friendship. Kathryn Olesko and Andrew Warwick functioned as de facto advisers every step of the way, and the book is better because of their engage- ment. While at Harvard I also completed doctoral work in theoretical physics; my thanks to Alan Guth, Robert Brandenberger, and Sidney Coleman for all their aid on my physics dissertation. Many physicists who were active in the period I describe have graciously shared their memories, correspondence, and lecture notes with me, and I am preface and acknowledgments xiii deeply grateful to them: Stephen Adler, the late Louis Balazs,` Michel Baranger, E. E. Bergmann, James Bjorken, John Bronzan, Laurie Brown, Kenneth Case, DenyseChew,GeoffreyChew,RoyChisholm,CarletonDeTar,FreemanDyson, Gordon Feldman, Jerry Finkelstein, William Frazer, Marvin Goldberger, the late A. Carl Helmholtz, Macalaster Hull, C. Angas Hurst, the late Morton Kaplon, Tom Kinoshita, Abraham Klein, Norman Kroll, Andrew Lenard, Joseph Levinger, Peter Lindenfeld, Francis Low, Stanley Mandelstam, Gor- don Moorhouse, Yoichiro Nambu, Roger Phillips, Silvan S. Schweber, Andrew Sessler, Howard Shugart, Henry Stapp, M. K. Sundaresan, Chung-I Tan, Kip Thorne, and Eyvind Wichmann. I have also benefited from the comments of many people who read part or all of this book in manuscript: Ron Anderson, James Bjorken, Alexander Brown, Laurie