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The Everett Interpretation of Quantum Mechanics

The Everett Interpretation of Quantum Mechanics: Collected Works 1955-1980 with Commentary

Copyright Date: 2012
Pages: 392
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    The Everett Interpretation of Quantum Mechanics
    Book Description:

    Hugh Everett III was an American physicist best known for his many-worlds interpretation of quantum mechanics, which formed the basis of his PhD thesis at Princeton University in 1957. Although counterintuitive, Everett's revolutionary formulation of quantum mechanics offers the most direct solution to the infamous quantum measurement problem--that is, how and why the singular world of our experience emerges from the multiplicities of alternatives available in the quantum world. The many-worlds interpretation postulates the existence of multiple universes. Whenever a measurement-like interaction occurs, the universe branches into relative states, one for each possible outcome of the measurement, and the world in which we find ourselves is but one of these many, but equally real, possibilities. Everett's challenge to the orthodox interpretation of quantum mechanics was met with scorn from Niels Bohr and other leading physicists, and Everett subsequently abandoned academia to conduct military operations research. Today, however, Everett's formulation of quantum mechanics is widely recognized as one of the most controversial but promising physical theories of the last century.

    In this book, Jeffrey Barrett and Peter Byrne present the long and short versions of Everett's thesis along with a collection of his explanatory writings and correspondence. These primary source documents, many of them newly discovered and most unpublished until now, reveal how Everett's thinking evolved from his days as a graduate student to his untimely death in 1982. This definitive volume also features Barrett and Byrne's introductory essays, notes, and commentary that put Everett's extraordinary theory into historical and scientific perspective and discuss the puzzles that still remain.

    eISBN: 978-1-4008-4274-2
    Subjects: Physics, General Science

Table of Contents

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  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-x)
    (pp. xi-xii)
    Jeffrey A. Barrett and Peter Byrne

    • CHAPTER 1 General Introduction
      (pp. 3-8)
      Jeffrey A. Barrett and Peter Byrne

      In July 2007,Naturecelebrated the half-centenary of the “many worlds” interpretation of quantum mechanics with a splashy cover and a series of explanatory articles. That year, there were two international conferences dedicated to dissecting Hugh Everett III’s claim that the universe is completely quantum mechanical.¹ Although the theorist had been dead for a quarter century, his controversial theory was alive and kicking.

      First published inReviews of Modern Physicsin 1957 as “The ‘Relative State’ Formulation of Quantum Mechanics,” the theory was not labeled “many worlds” until 1970, and then, not by Everett, but by his enthusiastic supporter, physicist...

    • CHAPTER 2 Biographical Introduction
      (pp. 9-25)
      Peter Byrne

      In the spring of 2007, the rock musician Mark Everett and the journalist Peter Byrne descended into the basement of the songwriter’s house in Los Angeles. One wall was lined with wooden shelves holding the family saga, two dozen cardboard boxes bursting with photographs and memorabilia and paper trails though time. They opened up his father’s boxes, which had been gathering dust since they had been packed a quarter century earlier.

      The musty cartons held old textbooks, physics and operations research papers, stacks of letters, used airplane tickets, cancelled checks to liquor stores, crumpled hotel receipts, a cheesy Super 8...

    • CHAPTER 3 Conceptual Introduction
      (pp. 26-54)
      Jeffrey A. Barrett

      Everett held that the two orthodox options for understanding quantum mechanics, the standard von Neumann–Dirac collapse formulation and Bohr’s Copenhagen interpretation, encountered the quantum measurement problem, and were hence ultimately untenable.

      The quantum measurement problem arises in the standard collapse theory from a conflict between its two dynamical laws. One law says that the state of a system evolves in a deterministic, linear way when no measurement is made of the system. The other law says that the state of a system evolves in a stochastic, nonlinear way when the system is measured. But the theory does not say...


    • CHAPTER 4 Minipaper: Objective versus Subjective Probability (1955)
      (pp. 57-60)

      This minipaper presents an early formulation of the quantum measurement problem in terms of a conflict between subjective and objective probabilities. Everett ultimately provided a much clearer formulation of the measurement problem in terms of a conflict between different state attributions in the long thesis. The structure of the experimental setup, however, is similar. There are two versions of this minipaper. One, handwritten, contains the drawing (pg. 15) of the Wigner’s Friend experiment. The second version (presented here) was typed after being edited and condensed from the handwritten draft.a


      Since the root of the controversy over the interpretation of...

    • CHAPTER 5 Minipaper: Quantitative Measure of Correlation (1955)
      (pp. 61-63)

      This minipaper lays some groundwork for the application of information theory as a measure of the degree of quantum correlation or entanglement. From very early in the project, Everett thought that Shannon information theory (Shannon and Weaver, 1949) would provide insight into pure wave mechanics. Although statistical measures, such as standard deviation, would have sufficed, Everett developed information theoretic measures to represent such things as the width of distributions and the degree of correlation between the states of multiple systems. He thought that the standard quantum uncertainty relations were best expressed in an information theoretic way. There are two versions...

    • CHAPTER 6 Minipaper: Probability in Wave Mechanics (1955)
      (pp. 64-70)

      This minipaper develops the basic premise of Everett’s thesis stripped of its formalism but laced with explanatory metaphors, such as splitting amoebas that share overlapping memories until diverging into separate futures recorded as consistent histories. There are several handwritten drafts of this minipaper and two typed versions, one turned into Wheeler. Wheeler made handwritten notes on his copy of this minipaper. These notes are presented here in the lettered footnotes.l

      Prof. Wheeler

      H. Everett

      In present formulations of quantum mechanics there are two essentially different ways in which the state of a system changes, one continuous and causal, and the...

    • CHAPTER 7 Correspondence: Wheeler to Everett (1955)
      (pp. 71-71)

      Wheeler thought that the correlation minipaper was close to being ready to be published. But he had serious reservations about “Probability and Wave Mechanics,” especially the splitting metaphors like the amoeba story that Everett had used to describe the branching structure exhibited by the linear superpositions of states represented by the universal wave function (see Wheeler’s notes on the paper itself for his cautions). More specifically, Wheeler said that the third minipaper was not ready for Bohr’s inspection “because of parts subject to mystical misinterpretations by too many unskilled readers.” Everpolitic, Wheeler was warning Everett that the metaphorical language he...

    • CHAPTER 8 Long Thesis: Theory of the Universal Wave Function (1956)
      (pp. 72-172)

      Everett’s long thesis was submitted to John Archibald Wheeler, his doctoral thesis advisor, in January 1956 under the title “Quantum Mechanics by the Method of the Universal Wave Function.” It was retitled “Wave Mechanics Without Probability” and circulated in April of that year to several prominent physicists, including Niels Bohr. The disapproval of Bohr and his colleagues, largely due to Everett’s direct criticism of the Copenhagen interpretation in the long thesis and their sense that Everett did not properly understand the current orthodoxy, led to the later short thesis. The short thesis, which Everett defended for his Ph.D., was a...

    • CHAPTER 9 Short Thesis: “Relative State” Formulation of Quantum Mechanics (1957)
      (pp. 173-196)

      Largely due to the criticism of the long thesis by the Copenhagen colleagues, Everett and his advisor John Wheeler rewrote Everett’s thesis in the winter of 1957 to produce a much shorter version, which Everett subsequently defended for his Ph.D. under the title “On the Foundations of Quantum Mechanics.” Whereas the long thesis was organized around the quantum measurement problem and how it is best solved by pure wave mechanics, the short thesis presented Everett’s relative-state formulation of pure wave mechanics more as a suitable theory for the development of quantum gravity, cosmology, and field theory. The short thesis no...

    • CHAPTER 10 Wheeler Article: Assessment of Everett’s “Relative State” Formulation of Quantum Theory (1957)
      (pp. 197-202)

      John Wheeler’s paper was published inReviews of Modern Physicsimmediately following Everett’s short thesis.eiIn his paper Wheeler sought both to endorse Everett’s relative-state formulation of pure wave mechanics and to put it in a context where it might be more acceptable to his colleagues. Although Wheeler’s support for Everett’s proposal faded over time, Everett remained steadfast in his commitment to the relative-state formulation.ej

      John A. Wheeler

      Palmer Physical Laboratory, Princeton University, Princeton, New Jersey

      The preceding paperekputs the principles of quantum mechanics in a new form.¹ Observations are treated as a special case of normal interactions that...


    • CHAPTER 11 Correspondence: Wheeler and Everett (1956)
      (pp. 205-213)

      In the spring of 1956, Wheeler was in residence at the University of Leiden, Netherlands. A copy of the long thesis was mailed to Bohr’s Institute for Theoretical Physics in April 1956. In May, Wheeler traveled to Copenhagen to discuss Everett’s theory with Bohr and Petersen. As Wheeler knew, Everett had already accepted a position as a weapons system analyst with WSEG, and he was eager to graduate. But the professor was reluctant to sign off on Everett’s dissertation unless his own mentor, Bohr, accepted at least the possibility that Everett was onto a potentially viable idea, suitable at least...

    • CHAPTER 12 Correspondence: Wheeler, Everett, and Stern (1956)
      (pp. 214-224)

      After Wheeler left Copenhagen, Alexander Stern, an American physicist in residence at Bohr’s Institute, led a seminar on Everett’s theory. He then wrote to Wheeler, critiquing the theory forcefully from the point of view of complementarity, labeling it “theology.” Interestingly, Stern referred to a prior correspondence in which Wheeler had compared the mathematics of game theory to Everett’s formulation of quantum mechanical formulation, since in both cases observers are included as a critical part of the theory itself. Although we have not found a copy of this letter, from Everett’s handwritten notes, it is clear that his approach to quantum...

    • CHAPTER 13 Correspondence: Groenewold to Everett (1957)
      (pp. 225-230)

      After losing the initial round of struggle with Bohr and his circle, Everett left Princeton in the spring of 1956, moving to the Washington, D.C., metropolitan area to commence working at WSEG, quickly establishing himself as WSEG’s chief mathematician and computer expert. He married Nancy Gore, who was pregnant with their first child, Elizabeth. He did not attend the January 1957 conference of gravitation in Chapel Hill, but shortly afterwards, he and Wheeler redacted and rewrote his dissertation (cutting it by 75 percent). He received his doctoral degree in April 1957, and his dissertation (with minor changes) was printed in...

    • CHAPTER 14 Correspondence: Everett and Wiener (1957)
      (pp. 231-235)

      Everett had long been an admirer of Massachusetts Institute of Technology Professor Norbert Wiener, whose path-breaking bookCybernetics or Control and Communications in the Animal and the Machine(Wiener, 1948) was a seminal influence on his own thinking about the role of information and probability in game theory and physics. So he must have been thrilled to receive a letter from Wiener in early April 1957, responding to the Everett and Wheeler preprints. It turned out that although Wiener liked Everett’s inclusion of the observer in the wave function of the system observed, he found fault with Everett’s derivation of...

    • CHAPTER 15 Correspondence: Everett and Petersen (1957)
      (pp. 236-240)

      Toward the end of April 1957, Everett received a letter from Petersen, reporting on how the two preprints had been received in Copenhagen. The gist of Petersen’s renewed critique was that Everett’s theory did not conform to Bohr’s principle of complementarity or his insistence on the special status of observation. Everett was, however, not at all interested in working within what he took to be a deeply flawed approach to quantum mechanics.

      Petersen to Everett, April 24, 1957

      24. 4. 57hl

      Dear Hugh,

      Thanks for sending the two papers.hmIt was good to see that your ideas are now going to...

    • CHAPTER 16 Correspondence: Everett and DeWitt (1957)
      (pp. 241-256)

      As an organizer of the Chapel Hill conference on gravitation, DeWitt was invited to guest-edit the July 1957 issue ofReviews of Modern Physics,which published the proceedings of the conference, including Everett’s short thesis and Wheeler’s companion paper extolling its virtues. DeWitt did not read the long thesis until many years later. In May 1957, DeWitt wrote a long and thoughtful letter to Wheeler about how Everett’s theory had conceptual parallels with Einstein’s theory of general relativity. DeWitt was unhappy with both wave function collapse and the Copenhagen interpretation. He wrote that Everett’s formalistic argument for pure wave mechanics...

    • CHAPTER 17 Correspondence: Everett and Frank (1957)
      (pp. 257-260)

      In Spring 1957, Everett corresponded with several supporters of his theory. Yale University professor Henry Margenau, for example, a physicist with a philosophical bent, wrote to Everett in April, after reading his preprint, commenting “The problem with which you deal has irritated many minds. I, for one, find your disposal quite acceptable.”

      In hisReviews of Modern Physicsarticle on Everett’s theory, Wheeler referenced the philosophical writings of Philip Frank, a philosopher of science at Harvard University. In May 1957, Everett sent Frank theReviews of Modern Physicspreprints, along with a letter in which he identified himself with Frank’s...

    • CHAPTER 18 Correspondence: Everett and Jaynes (1957)
      (pp. 261-264)

      In May 1957, the first of a pair of related papers by E. T. Jaynes appeared in the journalPhysical Review.In these papers Jaynes sought to apply Shannon information theory to statistical mechanics with the aim, in part, of providing an account of thermodynamic probabilities.

      Everett saw a direct connection between Jayne’s project of providing probabilities for classical statistical mechanics and his own project of providing probabilities for pure wave mechanics, but he disagreed with Jaynes on the proper way to carry out such a project. Everett argued that Jaynes’ subjectivist approach did not avoid the problem of having...


    • CHAPTER 19 Transcript: Conference at Xavier University (1959)
      (pp. 267-279)

      In 1959, Everett and his young family traveled to Copenhagen and spent several weeks vacationing. Mixing business with pleasure, Everett met with Bohr several times to discuss his theory. But the two men found little to agree on concerning quantum mechanics. Bohr smoked his briar pipe and mumbled obscurely in their meetings, as was his trademark behavior in old age. Everett spent a good deal of time bar-hopping. And in the bar of the Hotel Østerport, after imbibing a few beers, he invented and wrote down on hotel stationery the generalized Lagrange multiplier method, sending it off to his WSEG...

    • CHAPTER 20 Notes: Everett on DeWitt (1970)
      (pp. 280-282)

      In July 1970, DeWitt lectured on “The Many-Universes Interpretation of Quantum Mechanics” at the Enrico Fermi International School of Physics, Villa Monastero, Varenna, Italy. DeWitt sent Everett a preprint of the paper and Everett penciled two remarks on it. The first remark “Goddamit, you don’t see it” was in response to DeWitt’s assertion in a footnote that Everett’s derivation of the Born rule was “not entirely satisfying.” The second comment, a slashing “yes” related to DeWitt’s remark that while branching worlds do not all have to conform to the laws of physics as we know them, one would never observe...

    • CHAPTER 21 Notes: Everett on Bell (1971)
      (pp. 283-290)

      Although he did no more work on quantum mechanics after his dissertation was published in 1957 (as far as we know), Everett kept tabs on reactions to his theory as it gained fame. He paid particular attention to a critique written by John Stewart Bell, a staff physicist at CERN, the particle accelerator complex in Geneva, Switzerland.

      Bell was an experimentalist whose passion was exploring the foundations of quantum mechanics. Attracted to Bohm’s hidden variables theory, he published a famous paper in 1964 (Bell, 1964) in which he proved that quantum mechanics ruled out the existence of the locally deterministic...

    • CHAPTER 22 Correspondence: Jammer, Wheeler, and Everett (1972)
      (pp. 291-298)

      In 1972–1973, while Max Jammer was researching his bookThe Philosophy of Quantum Mechanics (1974),he corresponded with Everett, who revealed much about his motivation in writing the thesis and his current assessment of the theory.

      Jammer to Wheeler, January 11, 1972

      Professor M. Jammer Ph. D.

      January 11, 1972

      Professor John A. Wheeler

      Department of Physics

      Princeton University

      Princeton, New Jersey

      Dear Professor Wheeler:

      I would be grateful to you if you could send me the address of Dr. Hugh Everett III who in March 1957 wrote his Ph. D. thesis at your institute.

      Being interested in certain...

    • CHAPTER 23 Transcript: Everett and Misner (1977)
      (pp. 299-310)

      As the many-worlds theory gained in popularity, Wheeler gradually disassociated himself from it, eventually disavowing it. In 1977, Wheeler and DeWitt invited Everett to give a talk on his theory at the University of Texas in Austin. Dressed in his customary black suit, he chain smoked while pacing and speaking in a rapid fire staccato. According to the physicist David Deutsch, who was there, Everett spoke of the many worlds as if they were physically, ontologically real, while dismissing the notion of a preferred basis problem (Byrne, 2010, pgs. 321–333).

      A few weeks after the Austin talk, Charles and...

    • CHAPTER 24 Correspondence: Everett and Lévy-Leblond (1977)
      (pp. 311-314)

      In 1976, a conference called “Fifty Years of Quantum Mechanics” was held at the University of Louis Pasteur, Strasbourg. It was attended by more than a dozen physicists, including a young French scientist, Jean-Marc Lévy-Leblond. Wheeler’s presentation was called, “Include the Observer in the Wave Function?” Wheeler had a history of vacillating on Everett’s theory, but now, 20 years after he had endorsed it inReviews of Modern Physics,he rejected Everett’s inclusion of the observer in the wave function, essentially upholding the Copenhagen interpretation.

      In 1977, Jean-Marc Lévy-Leblond wrote a letter to Everett, including a copy of a paper...

    • CHAPTER 25 Correspondence: Everett and Raub (1980)
      (pp. 315-316)

      After the Austin meeting, Wheeler and DeWitt encouraged Everett to return to academia and do more work on quantum theory. But Everett was not interested. He was consumed by financial and personal troubles, including his debilitating addictions to alcohol, food, tobacco, and sex. However, in 1980 he responded to a letter from a physics enthusiast, David Raub, with several important remarks about how he viewed his theory.

      Everett to Raub, April 7, 1980

      Hugh Everett, III

      8114 Touchstone Terrace

      Mclean, Va. 22102


      April 7, 1980

      L. David Raub

      2559 Brandon Road

      Columbus, OH 43221

      Dear Mr. Raub,

      In answer...


    • APPENDIX A Everett’s Notes on Possible Thesis Titles
      (pp. 319-320)
    • APPENDIX B Early Draft Outline for Long Thesis
      (pp. 321-323)
    • APPENDIX C Universal Wave Function Note
      (pp. 324-325)
    • APPENDIX D Handwritten Draft Introduction to the Long Thesis
      (pp. 326-347)
    • APPENDIX E Handwritten Draft Conclusion to the Long Thesis
      (pp. 348-354)
    • APPENDIX F Handwritten Revisions to the Long Thesis for Inclusion in DeWitt and Graham (1973)
      (pp. 355-363)
    • APPENDIX G Handwritten Notes on Everett’s Copy of DeWitt and Graham (1973)
      (pp. 364-366)
    (pp. 367-368)
    Peter Byrne
    (pp. 369-374)
  11. INDEX
    (pp. 375-389)