Seeing Double: Shared Identities in Physics, Philosophy, and Literature

CHOICE Outstanding Academic Book for 2002

The separateness and connection of individuals is perhaps the central question of human life: What, exactly, is my individuality? To what degree is it unique? To what degree can it be shared, and how? To the many philosophical and literary speculations about these topics over time, modern science has added the curious twist of quantum theory, which requires that the elementary particles of which everything consists have no individuality at all. All aspects of chemistry depend on this lack of individuality, as do many branches of physics. From where, then, does our individuality come?

In Seeing Double, Peter Pesic invites readers to explore this intriguing set of questions. He draws on literary and historical examples that open the mind (from Homer to Martin Guerre to Kafka), philosophical analyses that have helped to make our thinking and speech more precise, and scientific work that has enabled us to characterize the phenomena of nature. Though he does not try to be all-inclusive, Pesic presents a broad range of ideas, building toward a specific point of view: that the crux of modern quantum theory is its clash with our ordinary concept of individuality. This represents a departure from the usual understanding of quantum theory. Pesic argues that what is bizarre about quantum theory becomes more intelligible as we reconsider what we mean by individuality and identity in ordinary experience. In turn, quantum identity opens a new perspective on us.

In this suggestive but almost terse volume, Pesic, a musician-physicist at St. John's College, probes the mysteries of individuality and identity in light of quantum theory. For Pesic, quantum theory poses a paradox: electrons and other elementary particles exhibit no individuality, yet we who are composed of these particles believe we are individuals. Every electron is so devoid of distinguishing features that one cannot even mark a particular electron to trace its history; they are perfectly identical instances of their species, a property Pesic christens "identicality." To explore the implications of identicality, Pesic looks not only to science but also to literature and philosophy. He considers Penelope's recognition of Odysseus in Homer's Odyssey, the ship of Theseus, Democritus, Leibniz, Kant, Martin Guerre, Conrad and Kafka, and hopscotches through the history of physics from Newton and Maxwell to Planck and the articulation of quantum theory in the 1920s. Pesic argues that the admittedly strange quantum realm becomes more intelligible if one treats the loss of individuality as a fundamental postulate rather than a peripheral consequence of scaling down the physical world. He concludes by suggesting how identicality may point to novel ways of viewing ourselves, perhaps as modes of a single field, existing through participation. The prose style is clear and accessible, the treatment concise and admirably suited for the author's goal of beginning "a thoughtful conversation among many people," including nonspecialists. But the issues are so large and compelling that the book's brevity is at times frustrating, particularly in its most crucial sections on quantum theory and its implications. Still, the book does a respectable job of opening the conversation it seeks.

Copyright 2002 Cahners Business Information, Inc.

*Starred Review* The '60s comedy troupe Firesign Theater famously asked, "How can you be in two places at once when you're really nowhere at all?" And everyone chuckled at the pun on the idiomatic meaning of being nowhere: being a square. It turns out, however, that that question restates a central inquiry of science and philosophy, which literature often ponders, too--to wit, Is identity resemblance or distinction? That is, does identity consist of being exactly like something else or being distinguishable from it? As Pesic imparts, the answer to the questions about identity is yes, and the answer to Firesign Theater's laugh line is, "Easy, if you're physical." Those are the answers because physical reality consists of unchanging things that are exactly alike and changing things that are individually distinct. The irreducible particles of quantum physics can "be" in two places simultaneously--but nowhere in particular--because they are indistinguishable. Meanwhile, bodies comprising those particles are distinct and can't be in more than one place at once. Pesic arrives at this puzzling understanding of existence by starting with the ancient Greeks' consideration of the identity problem in literature, myth, and philosophy, and proceeding through medieval thought to the Newtonian era, the nineteenth-century eruption in physics, and quantum physics. In passing, he cites literary treatments of double identity to illustrate what the scientific controversies imply, and he suavely creates a masterpiece by saying much in little space. Ray Olson
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