Since 1926, when wave mechanics and matrix formulations of quantum mechanics were first published, there have been efforts on the part of physicists, philosophers and science historians to interpret and further our understanding of quantum theory. Hugh Everett III conceived of the many-worlds interpretation of quantum mechanics as a graduate student at Princeton University. Everett called his interpretation the “relative state” formulation of quantum mechanics, and published a paper by that name in Reviews of Modern Physics in 1957. Since that publication, there has been growing interest in and scholarly analysis of Everett’s concepts.

David Wallace, a physicist and a philosopher, has written a modern account of the Everett interpretation and its logical consequences and extensions. Readers who are familiar with quantum mechanics at the undergraduate level, probability theory and decision theory would be well-suited to tackle the mathematical and logical arguments presented here. The book includes 60 pages of appendices and a number of formal proofs of theorems cited in the text. Key references, websites and a useful index are also provided at the end. Wallace makes a compelling case in support of the Everett interpretation, and this book is a major contribution to the current dialogue on the nature of physical reality.

Barry R. Masters is a Fellow of AAAS, OSA and SPIE. He is with the department of biological engineering at the Massachusetts Institute of Technology in Cambridge, Mass., U.S.A.

The opinions expressed in the book review section are those of the reviewer and do not necessarily reflect those of OPN or OSA.