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In a critique of the Copenhagen dogma, a physicist gives voice to “quantum dissidents”

What Is Real? The Unfinished Quest for the Meaning of Quantum Physics

Adam Becker
Basic Books
2018
381 pp/
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A century after its inception, quantum mechanics continues to puzzle us with dead-and-alive cats, waves “collapsing” into particles, and “spooky action at a distance.” In his first book, What Is Real?, science writer and astrophysicist Adam Becker sets out to explore why the physics community is still arguing today about quantum mechanics’s true meaning.

For Becker, this lack of progress is unsurprising: Most physicists still frame quantum problems through the sole lens of the so-called “Copenhagen interpretation,” the loose set of assumptions Niels Bohr and his colleagues developed to make sense of the strange quantum phenomena they discovered in the 1920s and 1930s. However, he warns, the apparent success of the Copenhagen interpretation hides profound failures.

The approach of Bohr and his followers, Becker argues, was ultimately rooted in logical positivism, an early-20th-century philosophical movement that attempted to limit science to what is empirically verifiable. By the mid-20th century, philosophers such as Thomas Kuhn and W. V. O. Quine had completely discredited this untenable view of science, Becker continues. The end of logical positivism, he concludes, should have led to the demise of the Copenhagen interpretation. Yet, physicists maintain that it is the only viable approach to quantum mechanics.

As Becker demonstrates, the physics community’s faith in Bohr’s wisdom rapidly transformed into a pervasive censorship that stifled any opposition. Advisers steered Ph.D. students away from questioning the “orthodox” interpretation of quantum mechanics, and journals systematically rejected papers that did so. It became difficult to obtain funding and apparatuses to test contested claims. Those who dared discuss possible alternatives to the “dogma” were ostracized.

A riveting storyteller, Becker brings to life physicists who have too long remained in the shadow of Bohr and Einstein. Drawing on a vast literature and scores of interviews, he weaves an engaging narrative in which Nazi science, communist sympathies, science-fiction magazines, Cold War strategists, hippies, and institutional feuds fueled heated disputes over alternative interpretations.

The book shows that more than mere philosophical disagreements explain why David Bohm was exiled to Brazil after proposing that electrons were guided by a pilot wave, why Hugh Everett III preferred to run nuclear war simulations for the Pentagon rather than defend the possibility of “parallel” worlds, and why so few of John Bell’s CERN co-workers knew about his groundbreaking work in quantum physics.

Unfortunately, in his eagerness to defend the critiques of the “Copenhagen dogma,” Becker fails to give a fair hearing to Bohr and his colleagues. He admits that the Copenhagen interpretation is not a monolithic doctrine but nevertheless usually presents it as one.

Of course, nontechnical primers are not the place for fastidious philosophical distinctions. They should, however, be careful not to create strawmen. Eugene Wigner may have claimed that only conscious observers collapse quantum wave functions, but Bohr did not. Grete Hermann argued that definite paths could be ascribed to electrons between measurements, but Werner Heisenberg dismissed such claims as “matters of personal preference.”

By suggesting that, for all practical purposes, these physicists defended the same position, Becker—like so many before him—ends up portraying the Copenhagen interpretation as a single, internally inconsistent doctrine. His uncharitable account makes it difficult not to conclude that these physicists were at best unsophisticated instrumentalists, at worst self-serving hypocrites.

The defense Bohr and his students gave of their positions drew from many philosophical traditions, including Aristotelian metaphysics, neo-Kantianism, and analytic philosophy of language. They were especially intrigued by how these schools of thought dared to ask if “what is real?” can be meaningfully answered. By failing to engage the Copenhagen physicists on their own terms, Becker is unsuccessful in addressing the fundamental philosophical question hiding behind the title of his work, a question that remains at the heart of quantum interpretation debates.

Despite an oversimplified treatment of the philosophical issues at play, What Is Real? offers an engaging and accessible overview of the debates surrounding the interpretation of quantum mechanics. It will appeal to those who wonder whether instantaneous actions at a distance are logically—let along physically—possible, as well as to those who, like Einstein, wonder if the Moon is still there when no one is looking.

About the author

The reviewer is director of the History of Science and Technology Programme, University of King’s College, Halifax, Nova Scotia B3H 2A1, Canada.