Richard Feynman, The Thinker (New York Times)

By GEORGE JOHNSON

Published: April 1, 2011

In the heyday of the physicist Richard P. Feynman, which ensued after his death in 1988, a publishing entrepreneur might have been tempted to start a book club of works by and about him. Offered as main selections would be Feynman’s autobiographical rambles (as told to Ralph Leighton), “ ‘Surely You’re Joking, Mr. Feynman!’ ” and“ ‘What Do You Care What Other People Think?’ ” For alternate selections, readers could choose from his more serious works, like“QED: The Strange Theory of Light and Matter” — a spirited account of the counterintuitive behavior of the quantum world — and the legendary “Feynman Lectures on Physics.” Whatever the man said had swagger. For those who would rather listen, there are recordings of the lectures and of Feynman playing his bongos.

SSPL/Getty Images

Richard P. Feynman, circa 1955.

QUANTUM MAN

Richard Feynman’s Life in Science

By Lawrence M. Krauss

Illustrated. 350 pp. Atlas & Company/W. W. Norton & Company. $24.95.

Excerpt: ‘Quantum Man’ (Google Books)

He was an irresistible subject for biographers and, as he called himself in two of his subtitles, a curious character indeed. The best biography, James Gleick’s “Gen­ius,”captured the ebullience — sometimes winning, sometimes exasperating — and gave lucid explanations of some hard physics. Those seeking a more mathematical treatment could turn to Jagdish Mehra’s thick book “The Beat of a Different Drum,” while for a lighter touch there was Christopher Sykes’s “No Ordinary Gen­ius: The Illustrated Richard Feynman.”

It is hard to imagine that the world needs another Feynman biography, but here it is. In “Quantum Man: Richard Feynman’s Life in Science,” Lawrence M. Krauss, director of the Origins Project at Arizona State University, makes his own way through the subject and emerges with an enlightening addition to the field. Krauss — like Feynman a physicist as well as an author — has written seven books, including “The Physics of Star Trek.” Though he couldn’t resist recycling some well-worn Feynman anecdotes (and providing a couple of his own), he concentrates on Feynman the thinker, and on the contributions that merited his fame.

It is not something easily summarized. Einstein discovered relativity. Murray Gell-Mann discovered the quark. And Feynman? Well, there was that thing he did on TV with the O-ring and the ice water, showing why the Challenger had disintegrated. But to physicists he is famous for something more obscure: cleaning up the mathematical mess known as quantum electrodynamics — an ambitious attempt to explain light and matter using two great theories, quantum mechanics and special relativity.

In 1965, he shared a Nobel Prize with two colleagues (Julian Schwinger and Sin-Itiro Tomonaga), who solved the problem in different ways. But Feynman’s “sum over paths” approach, expressed in the lines and squiggles of what became known as Feynman diagrams, opened up a more intuitive understanding of the subatomic realm. It was, as Krauss puts it, “a beautiful pictorial way of thinking about quantum mechanics.”

Other good books give a feel for this and Feynman’s later accomplishments. But I understood it all better after watching over the shoulder of Krauss the physicist as he worked his way through the Feynman oeuvre — not the stories of fast times in Rio, but the scientific papers.

In popular lore, Feynman often comes off as the wild man of physics, throwing out one crazy idea after another in a frenzied search for truth. In “Quantum Man” — part of the “Great Discoveries” series, for which I have also written a book — we see more of his other side: a master mathematician who could concentrate on a problem for hours and then recast it in a surprising new manner.

In following the chain of ideas that led to Feynman’s Nobel, Krauss begins with a familiar phenomenon — the way a light ray takes a sudden bend when it enters a pool of water. The angle can be calculated using a staple of high school physics called Snell’s law, but in the 17th century Pierre de Fermat provided a deeper explanation: the light beam acts as though it were trying to minimize its total travel time. Light moves more slowly in water than in air, so it adjusts its course, ensuring that it spends no longer than necessary in the denser medium. The idea is not that the light beam is thinking ahead but that the universe is somehow structured so it appears that way.

During the next century, mathematicians showed that Newton’s laws of motion could be rewritten in a similar vein: an orbiting planet or a hurtling cannonball moves as though it were trying to minimize a more abstract quantity called “action.” Krauss gives readers a feel for what that means and shows how Feynman retooled the idea to solve some nagging problems in subatomic physics.

One of science’s great puzzles (still only partly solved) is how to reconcile the regularities of classical physics — like the bending light beam — with the probabilistic laws of quantum mechanics. Light, after all, consists of photons, which are capable of doing all kinds of strange things. In moving from A to B, a photon may take any number of different paths, even ones that seem absurd — spiraling in curlicues, changing speeds in midair. With Feynman’s method, these acrobatics can be added together, the weirdest ones canceling one another out, to yield the motion we observe in the familiar world.

This triumph came early in his career. His later thinking (about solid-state physics, for example, or quantum cosmology) was just as original. Maybe sometimes too original, Krauss suggests. Science usually proceeds by building on what came before. The maverick in Feynman kept him from accepting even the most established ideas until he had torn them apart and reassembled the pieces. That led to a deeper understanding, but his time might have been better spent at the cutting edge.

“He continued to push physics forward as few modern scientists have,” Krauss writes, “but he tended to lead from the rear or, at best, from a side flank.”

Like those quantum particles, he seemed eager to try every path — even the crazy ones. That was true in his life as well as in his physics.

George Johnson is the author of eight books, including “Strange Beauty: ­Murray Gell-Mann and the Revolution in Twentieth-Century Physics.”

A version of this review appeared in print on April 3, 2011, on page BR19 of the Sunday Book Review.
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