It has been 61 years since Hugh Everett III's PhD dissertation, {\it On the Foundations of Quantum Mechanics}, was submitted to the Princeton University Physics Department. After more than a decade of relative obscurity it was resurrected by Bryce DeWitt as {\it The Many Worlds Interpretation of Quantum Mechanics} and since then has become an active topic of discussion, reinterpretation, and modification, especially among philosophers of science, quantum cosmologists, and advocates of quantum decoherence and quantum computing. Many of these analyses are quite sophisticated and considered to be important contributions to physics and philosophy. I am primarily an experimental physicist and my pragmatic ruminations on the subject might viewed with some suspicion. Indeed, Bohr's pragmatic {\it Copenhagen Interpretation} is often disparaged by this same cohort. Still, I think that my experimentalist's vantage point has something to offer and I here offer it to you.
It has been 61 years since Hugh Everett III's PhD dissertation, {\it On the Foundations of Quantum Mechanics}, was submitted to the Princeton University Physics Department. After more than a decade of relative obscurity it was resurrected by Bryce DeWitt as {\it The Many Worlds Interpretation of Quantum Mechanics} and since then has become an active topic of discussion, reinterpretation, and modification, especially among philosophers of science, quantum cosmologists, and advocates of quantum decoherence and quantum computing. Many of these analyses are quite sophisticated and considered to be important contributions to physics and philosophy. I am primarily an experimental physicist and my pragmatic ruminations on the subject might viewed with some suspicion. Indeed, Bohr's pragmatic {\it Copenhagen Interpretation} is often disparaged by this same cohort. Still, I think that my experimentalist's vantage point has something to offer and I here offer it to you.
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.
Recent years have seen a good deal of work done on one of the most mind blowing and conceptually radical views in quantum mechanics, namely the ‘many worlds’ interpretation of quantum mechanics. Many worlds was first proposed by Hugh Everett III in his long Ph.D. dissertation, which only some years later, and after significant shortening, came to be published as the ‘Relative State Formulation of Quantum Mechanics’ (Everett 1957). To commemorate the 50th anniversary of the first publication of Everett's ideas, two conferences were held at Oxford University and the Perimeter Institute, which brought together some of the most active researchers in the field. The works presented in these two conferences have now been compiled in the volume Many Worlds? Everett, Quantum Theory and Reality, edited by Simon Saunders, Jonathan Barrett, Adrian Kent and David Wallace.1 This is then a comprehensive collection of papers – 23 papers altogether – where the reader will find virtually anything that can be said about the many worlds interpretation today.
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.
The Many-worlds Interpretation (MWI) of quantum mechanics has captivated physicists and philosophers alike since its inception in the mid-20th century. This paper explores the historical roots, evolution, and implications of the MWI within the context of quantum theory. Beginning with an overview of early developments in quantum mechanics and the emergence of foundational interpretations, we delve into the origins of the MWI through the groundbreaking work of physicist Hugh Everett III. Everett's doctoral thesis proposed a radical solution to the measurement problem, positing the existence of multiple branching universes to account for quantum phenomenon. We trace the evolution of the MWI, examining its refinement and elaboration by subsequent physicists such as John Wheeler. Furthermore, we discuss the MWI's impact on contemporary physics, including its connections to quantum information theory and ongoing experimental tests. By providing a comprehensive analysis of the MWI's historical development and current relevance, this paper offers insights into one of the most provocative interpretations of quantum mechanics and its implications for our understanding of the universe.
abstract: This thesis attempts to explain Everettian quantum mechanics from the ground up, such that those with little to no experience in quantum physics can understand it. First, we introduce the history of quantum theory, and some concepts that make up the framework of quantum physics. Through these concepts, we reveal why interpretations are necessary to map the quantum world onto our classical world. We then introduce the Copenhagen interpretation, and how many-worlds differs from it. From there, we dive into the concepts of entanglement and decoherence, explaining how worlds branch in an Everettian universe, and how an Everettian universe can appear as our classical observed world. From there, we attempt to answer common questions about many-worlds and discuss whether there are philosophical ramifications to believing such a theory. Finally, we look at whether the many-worlds interpretation can be proven, and why one might choose to believe it. (abstract)
The Everett interpretation of quantum mechanics - better known as the Many-Worlds Theory - has had a rather uneven reception. Mainstream philosophers have scarcely heard of it, save as science fiction. In philosophy of physics it is well known but has historically been fairly widely rejected. Among physicists (at least, among those concerned with the interpretation of quantum mechanics in the first place), it is taken very seriously indeed, arguably tied for first place in popularity with more traditional operationalist views of quantum mechanics. In this article, I provide a fairly short (15,000 words) and self-contained introduction to the Everett interpretation as it is currently understood. I use little technical machinery, although I do assume the reader has encountered the measurement problem already (at about the level of the well-known discussions by Penrose or Albert).