Uncertainty: Einstein, Heisenberg, Bohr, and the Struggle for The Soul of Science , David Lindley , Doubleday, New York, 2007. $26.00 (257 pp.). ISBN 978-0-385-51506-1
If I were to pick one idea from modern physics that has seeped into popular culture, it would be the Heisenberg uncertainty principle. More than Albert Einstein's theory of relativity, it pops up in the most unexpected places. David Lindley rolls out a few choice examples toward the end of his new book, Uncertainty: Einstein, Heisenberg, Bohr, and the Struggle for the Soul of Science. One involves a news editor commenting on embedded news reporting in Iraq, claiming that “the more precisely the media measures individual events in a war, the more blurry the warfare appears to the observer.” Another is Claudia Jean “C. J.” Cregg, the press officer in the television series The West Wing, who is being followed by a “fly on the wall” filmmaker and is asked if it has been a typical day at the White House: “I don't have to tell you about the Heisenberg principle,” she responds knowingly.
Of course, I should have thrown the book across the room in anger, but I didn't. Because Lindley has done a pretty good job in sorting out the tangled ideas of quantum physics, his book just might lead the general public to understand what the principle is all about.
In his earlier book, Boltzmann's Atom: The Great Debate That Launched a Revolution in Physics (Free Press, 2001), Lindley tackles a similarly ubiquitous concept: entropy. He tells a compelling narrative of Ludwig Boltzmann and how the troubled physicist slowly came up with his view of statistical physics. Boltzmann's Atom portrays a complex man caught up in the fight between the atomists and the phenomenologists. His erratic career path in physics and his untimely death were a result of his lifelong battle with depression. The definition of entropy, the idea of irreversibility, and the birth of the quantum emerge from a life steeped in irrationality. The mix of emotion and high concept worked incredibly well.
In Uncertainty , Lindley tries the same approach, albeit on a grander scale. To faithfully narrate the development of quantum physics, he had to weave together the stories of numerous characters. There is, of course, Werner Heisenberg, an ascetic young man whom Niels Bohr described as “a little peasant boy, … very quiet, friendly and shy.” Espousing the approach of Max Born, his mentor, that a proper theory must be expressed in terms of formal mathematics, Heisenberg came up with the matrix formulation of quantum mechanics. It was, he claimed, an attempt “to obtain foundations of quantum mechanics based exclusively on relationships between quantities that are in principle observable.” One of those relationships is the inability to simultaneously observe the position and momentum of a particle: the uncertainty principle.
Bohr plays a lead role. Lindley gives readers an insight into Bohr's ability to come up with groundbreaking ideas based on broad concepts and assumptions that lead to hard numbers. Yet, as Lindley tells us, “for a man counted among the great theorists of physics, Bohr had remarkably little ability in the higher realms of mathematics.” It was when he joined forces with the mathematically inclined Arnold Sommerfeld that the full explanatory power of Bohr's hydrogen atom was unleashed. Bohr comes across in the book as the godfather of the quantum, always alert to developments, sometimes confused by the different formulations, but a guiding light to Heisenberg, Erwin Schrödinger, Wolfgang Pauli, and the great young physicists who follow.
Einstein comes across as the cantankerous old uncle, overtaken by events and skeptical of the path modern physics is taking. He writes of Heisenberg's seminal paper: “Heisenberg has laid a large quantum egg. In Göttingen they believe it (I don't).” Although, over the years, Einstein was a source of many disparaging remarks about the new theory, he did at some point engage with it. For example, with Boris Podolsky and Nathan Rosen, he came up with a thought experiment that neatly showed some of the strange and, to him, unacceptable consequences of quantum mechanics: correlations of physical properties at spacelike separations.
Uncertainty is a mess of ideas and characters, a compelling read. Lindley has successfully created an arc and has been careful not to overly systematize the events that flesh it out. He has been able to profitably give us a real sense of the process of discovery in the early 20th century, as Europe hurtled toward war and the repression of intellectual life. Chaos was the essential background to the emergence of the quantum, the gem of modern physics. Editors, journalists, and scriptwriters should read the book before they cherry pick any more quantum concepts. They will enjoy it and will look less foolish.
Pedro G. Ferreira is a reader in physics at the University of Oxford in the UK. His interests are in cosmology, the early universe, the cosmic microwave background, and astroparticle physics. He is the author of The State of the Universe: A Primer in Modern Cosmology (Weidenfeld and Nicholson, 2006).