The Beat ofa Different Drum

The Life and Science of Richard Feynman

JAGDISH MEHRA

CLARENDON PRESS OXFORD CONTENTS

Introduction

1 'If it's a boy, he'll be a scientist' 1 2 'What one fool can do, another can do better' 22 3. Undergraduate at MIT 44 3.1 Applying to College 44 3.2 Bright College days 45 3.3 'The limitations of reason' 61 3.4 Chief chemist at Metaplast Corporation 66 3.5 Research on cosmic rays as an undergraduate 69 3.6 Feynman's senior thesis: 'Forces and Stresses in molecules' 71 3.7 Pastures new 79 4. Arrival in Princeton as a graduate Student 81 4.1 Settlingin 81 4.2 Graduate studies 85 4.3 Feynman's MIT program 89 5. Action-at-a-distance in electrodynamics: the 92 Wheeler-Feynman theory 5.1 Wheeler's modification of Feynman's ideas 92 5.2 The historical context of time-symmetric electrodynamics 101 5.3 Electrodynamics without the electromagnetic field: the 107 Wheeler-Feynman theory 6 The principle of least action in quantum 117 mechanics 6.1 Introduction 117 XIV Contents

6.2 Formulation of the problem 120 6.3 Least action in classical mechanics 123 6.4 Feynman's simple 'toy' modeis 130 6.5 Feynman's invention of the new method for the 134 quantization of classical Systems 6.6 Further development of Feynman's results in his thesis 138 7 Arline: 'A love like no other I know' 143 8 Diversions and contributions at Los Alamos 151 9 A 'dignified professor' at Cornell University 161 10 Feynman's path to quantum mechanics 182 10.1 Introduction 182 10.2 The path-integral 183 10.3 The new Operator algebra 187 10.4 Functional integration before Feynman 192 (a) VitoVolterra 192 (b) Norbert Wiener and others 192 (c) Subrahmanyan Chandrasekhar 196 10.5 Possible generalization and some applications 198 11 The development of quantum 203 electrodynamics until mid-1947: the historical background of Feynman's work on QED 11.1 P. A. M. Dirac's theory of radiation 203 11.2 Dirac, Heisenberg, Pauli, and Fermi's relativistic radiation 205 theory 11.3 Dirac's hole theory, spin, and statistics 207 11.4 The inifinities in quantum electrodynamics 210 11.5 The earlier attempts to overcome the inifinities in 213 quantum electrodynamics 11.6 The earlier experimental evidence for the deviations from 216 Dirac's theory of the electron 11.7 The post-war development and the Shelter Island 216 Conference 12 Feynman's investigations between the Shelter 223 Island and Pocono Conferences 12.1 Hans Bethe's calculation of the Lamb shift 223 12.2 'I can do that for you!' 226 12.3 The genesis of Feynman's approach to quantum 229 electrodynamics: between the Shelter Island and Pocono Conferences Contents xv 12.4 Richard Feynman at the Pocono Conference 245

13 From the Pocono Conference to the 251 Oldstone Conference: Feynman's fundamental papers on quantum electrodynamics 13.1 The relativistic cut-off for classical electrodynamics 251 13.2 The relativistic cut-off for quantum electrodynamics 255 13.3 The summer and fall of 1948 260 13.4 The APS meeting of January 1949 266 13.5 The Pauli-Villars regularization 270 13.6 The theory ofpositrons 271 13.7 The Oldstone Conference 278

14 The space-time approach to quantum electrodynamics 282 14.1 Introduction 282 14.2 The interaction between charges 284 14.3 The self-energy problem 288 14.4 Expression in momentum and energy space: the Feynman 289 diagrams 14.5 The problem of vacuum polarization 294 14.6 Some other results and concluding remarks 297

15 The mathematical formulation of quantum 301 electrodynamics 15.1 Introduction 301 15.2 Mathematical formulation of the quantum theory of 302 electromagnetic interaction 15.3 An Operator calculus having applications in quantum 307 electrodynamics 15.4 Application in quantum mechanics and quantum 310 electrodynamics 15.5 Dyson's elaboration of the theories of Feynman, 314 Schwinger, and Tomonaga 15.6 The Dirac equation 318 15.7 Functional integration and the path-integral method 321 15.8 Some concluding remarks 324

16 From Cornell to Caltech via Copacabana 330 and Kyoto XVI Contents 17 The cup runneth over: Feynman and the 348 theory of superfluidity 17.1 Introduction 348 17.2 Historical background 351 17.3 The two-fluid model of Tisza and London 353 17.4 Landau's theory of elementary excitations: phonons and 355 rotons 17.5 The experiments of Andronikashvili and Peshkov 358 17.6 The new roton spectrum 359 17.7 Bogoliubov's theory of quasi-particles in an imperfect 361 Böse gas 17.8 Enter Feynman 363 17.9 Feynman's theory of a Böse liquid 364 17.10 Feynman's derivation of the energy spectrum of 367 elementary excitations 17.11 An earlier attempt by Bijl 369 17.12 The Feynman-Cohen treatment of the'backflow' 371 17.13 Direct determination of the energy spectrum 372 17.14 The flow phenomena 376 17.15 Landau on the critical velocity of superflow 377 17.16 Feynman's theory of quantized vorticity 378 17.17 Feynman on the critical velocity of superflow 381 17.18 The 'rotation' of the superfluid 382 17.19 Feynman and the quantized vortex rings 385 18 Un welcome recognition and establishing a 392 routine 19 'Enjoying the scenery': Feynman and the 404 polaron problem 19.1 Introduction 404 19.2 The historical background of the polaron problem 405 19.3 Feynman's path-integral approach to the ground-state 411 properties of the polaron (1955) 19.4 Initial reception of Feynman's 1955 paper and Schultz's 417 early elaborations 19.5 Polaron mobility and the contributions of Schultz, FHIP, 420 and Thornber (a) Generalities 420 (b) Schultz's contribution 421 (c) FHIP's contribution (1962) 424 (d) The contribution of Thornber and Feynman 426 19.6 Contemporary developments ä la Feynman 427 19.7 Connection with superconductivity 428 Contents xvii 20 Excursions into diverse fields 433 20.1 Bringing quantum mechanics to engineering 433 20.2 A 'graduate Student' in biology 438 20.3 There's plenty of room at the bottom 441 20.4 Selecting school textbooks for science and mathematics 447 21 'The only law of nature I could lay a claim 453 to': The theory of weak interactions 21.1 Historical introduction 454 21.2 Fermi's theory of beta decay 457 21.3 Question of parity and the theta-tau puzzle 459 21.4 Richard Feynman and the problem of weak interactions 462 21.5 Another important contribution to the law of beta decay 467 21.6 The universal Fermi interaction 469 (a) Chirality invariance 470 (b) The two-component spinor formulation of the Dirac 471 spinors (c) Mass-reversal invariance 473 (d) Connection with the V-A interaction 473 21.7 The conserved vector current hypothesis 474 (a) Analogy with electromagnetism 474 (b) The conserved electromagnetic current 475 (c) The formulation of the conserved vector current: 476 (CVC) theory 21.8 Some personal consequences of the work on UFI 477 22 Virtuoso Performances as teacher and 482 lecturer 22.1 The Feynman lectures on physics 489 22.2 The character of physical law 497 22.3 QED: The Strange theory of light and matter 499 23 Gravitons, partons, and quark jets 503 23.1 The quantum theory of gravitation 503 23.2 Partons 507 23.3 Quark jets 514 (a) Introduction 514 (b) Experimental Observation of jets 516 (c) Hadronization/fragmentation 519 (d) The independent fragmentation scheme 521 24 The fundamental limits of computation 525 24.1 Introduction: Feynman's interest in Computers 525 24.2 Information as a physical quantity 528 XV1H Contents

24.3 Energy dissipation as a result of information processing 530 24.4 Models of classical reversible Computers 531 24.5 Models of quantum mechanical reversible Computers 534 24.6 Feynman's model of a quantum Computer 537 24.7 Further developments of Feynman's ideas 538 24.8 The underlying discrete structure of the universe 539 25 Reflections on science, religion, culture, and 543 modern society 25.1 The value of science 543 25.2 The relation of science to religion 545 25.3 The role of science in the world today 548 25.4 The role of scientific culture in modern society 554 25.5 Cargo Cult Science 561 26 The beat of a different drum 567 26.1 Settling down to married life 567 26.2 The Nobel Prize 573 26.3 Offer of an honorary doctorate and other honors 577 26.4 A variety of glimpses into Feynman's life and personality 579 (a) Art and drawing 579 (b) Gianonni's topless bar 583 (c) Ceremony for blessing the animals 584 (d) Theater and drama 585 (e) Mayan hieroglyphics 586 (f) That wouldn't be rational!' 587 (g) Relations with students and colleagues 588 (h) Fashions in physics 591 (i) Attitüde towards nature and physics 591 26.5 The space Shuttle Challenger 594 26.6 Tannu Tuva: 'The last journey of a genius' 599 26.7 Final stay in the hospital 606 Index 613

Platesfall between pages 320 and 321