The everett interpretation of quantum mechanics

The Everett Interpretation of Quantum Mechanics This page intentionally left blank The Everett Interpretation of Quantum Mechanics COLLECTED WORKS 1955–1980 WITH COMMENTARY HUGH EVERETT III Edited by JEFFREY A BARRETT and PETER BYRNE PRINCETON UNIVERSITY PRESS PRINCETON & OXFORD Copyright c 2012 by Princeton University Press Published by Princeton University Press, 41 William Street, Princeton, New Jersey 08540 In the United Kingdom: Princeton University Press, Oxford Street, Woodstock, Oxfordshire OX20 1TW press.princeton.edu All Rights Reserved Library of Congress Cataloging-in-Publication Data Everett, Hugh The Everett interpretation of quantum mechanics : collected works 1955–1980 with commentary / Hugh Everett, III; editors, Jeffrey A Barrett and Peter Byrne p cm Includes bibliographical references and index ISBN 978-0-691-14507-5 (hardcover : acid-free paper) Quantum theory Everett, Hugh I Barrett, Jeffrey Alan II Byrne, Peter, 1952– III Everett, Hugh Selections IV Title QC174.12.E96 2012 530.12–dc23 2011037956 British Library Cataloging-in-Publication Data is available This book has been composed in Sabon LT Std Printed on acid-free paper ∞ Typeset by S R Nova Pvt Ltd, Bangalore, India Printed in the United States of America 10 Reality resists imitation through a model —Erwin Schrödinger, The Present Situation in Quantum Mechanics (1935) Once we have granted that any physical theory is essentially only a model for the world of experience, we must renounce all hope of finding anything like “the correct theory.” —Hugh Everett III, The Theory of the Universal Wave Function (1973) This page intentionally left blank CONTENTS PREFACE PART I INTRODUCTION xi CHAPTER General Introduction Everett and His Project Everett’s Target: The Measurement Problem 3 CHAPTER Biographical Introduction Basement Treasure Life of Everett: The Short Story Origins of the Theory To Split or Not To Split Operations Research The Theory Matures 9 10 11 17 19 21 CHAPTER Conceptual Introduction The Quantum Measurement Problem Everett’s Proposed Resolution Interpretations of Everett On the Faithful Interpretation of Everett PART II THE EVOLUTION OF THE THESIS 26 27 34 37 50 55 CHAPTER Minipaper: Objective versus Subjective Probability (1955) 57 CHAPTER Minipaper: Quantitative Measure of Correlation (1955) 61 CHAPTER Minipaper: Probability in Wave Mechanics (1955) 64 CHAPTER Correspondence: Wheeler to Everett (1955) 71 CHAPTER Long Thesis: Theory of the Universal Wave Function (1956) Introduction Probability, Information, and Correlation 72 72 80 viii • Contents Quantum Mechanics Observation Supplementary Topics Discussion Appendix I Appendix II: Remarks on the Role of Theoretical Physics 95 117 133 151 159 168 CHAPTER Short Thesis: “Relative State” Formulation of Quantum Mechanics (1957) Introduction Realm of Applicability of the Conventional or “External Observation” Formulation of Quantum Mechanics Quantum Mechanics Internal to an Isolated System Concept of Relative State Observation Discussion 173 175 175 178 179 183 196 CHAPTER 10 Wheeler Article: Assessment of Everett’s “Relative State” Formulation of Quantum Theory (1957) 197 PART III THE COPENHAGEN DEBATE 203 CHAPTER 11 Correspondence: Wheeler and Everett (1956) Wheeler to Everett, May 22, 1956 Wheeler Notes on Conversation with Petersen, May 3, 1956 Wheeler to Everett, May 26, 1956 Wheeler to Everett, September 17, 1956 205 205 207 211 212 CHAPTER 12 Correspondence: Wheeler, Everett, and Stern (1956) Stern to Wheeler, May 20, 1956 Wheeler to Stern, May 25, 1956 Wheeler to Everett, May 25, 1956 214 215 219 223 CHAPTER 13 Correspondence: Groenewold to Everett (1957) Groenewold to Everett and Wheeler, April 11, 1957 225 226 CHAPTER 14 Correspondence: Everett and Wiener (1957) Wiener to Wheeler, April 9, 1957 Everett to Wiener, May 31, 1957 231 231 234 Contents • ix CHAPTER 15 Correspondence: Everett and Petersen (1957) Petersen to Everett, April 24, 1957 Everett to Petersen, May 31, 1957 236 236 238 CHAPTER 16 Correspondence: Everett and DeWitt (1957) DeWitt to Wheeler, May 7, 1957 Everett to DeWitt, May 31, 1957 241 242 252 CHAPTER 17 Correspondence: Everett and Frank (1957) Everett to Frank, May 31, 1957 Frank to Everett, August 3, 1957 257 257 259 CHAPTER 18 Correspondence: Everett and Jaynes (1957) Everett to Jaynes, June 11, 1957 PART IV POST-THESIS CORRESPONDENCE AND NOTES 261 262 265 CHAPTER 19 Transcript: Conference at Xavier University (1959) 267 CHAPTER 20 Notes: Everett on DeWitt (1970) 280 CHAPTER 21 Notes: Everett on Bell (1971) 283 CHAPTER 22 Correspondence: Jammer, Wheeler, and Everett (1972) Jammer to Wheeler, January 11, 1972 Wheeler to Jammer, March 19, 1972 Jammer to Everett, August 28, 1973 Everett to Jammer, September 19, 1973 291 291 292 293 294 CHAPTER 23 Transcript: Everett and Misner (1977) 299 CHAPTER 24 Correspondence: Everett and Lévy-Leblond (1977) Lévy-Leblond to Everett, August 17, 1977 Everett to Lévy-Leblond, November 15, 1977 311 311 313 .. .The Everett Interpretation of Quantum Mechanics This page intentionally left blank The Everett Interpretation of Quantum Mechanics COLLECTED WORKS 1955–1980 WITH COMMENTARY HUGH EVERETT. .. device and the rest of the universe) outside the wave function of the quantum object observed Everett was not the first physicist to think in these terms In 1935, the inventor of wave mechanics, ... of his thesis, DeWitt’s interpretation of Everett so captured people’s imagination that it remains the most popular understanding of Everett s theory.9 Nonetheless, a half century after the theory