Are physicists stringing science along?

Review Science

October 15, 2006|By K.C. Cole | K.C. Cole,Los Angeles Times

Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law

Peter Woit

The Trouble With Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next

Lee Smolin

Houghton Mifflin / 392 pages / $26

..

In physics, truth and beauty often walk hand in hand. Physicists describe theories as "ugly" or "beautiful," talk about ideas that "smell" or "feel" right. Often, esthetic judgments lead to discoveries: as in Einstein's theory of gravity and Paul A.M. Dirac's discovery of antimatter. Esthetics, the French physicist Henri Poincare said, is a "delicate sieve" that sorts the true from the misleading. Or as Dirac famously put it: "It is more important to have beauty in one's equations than to have them fit experiment."

To the mathematician Peter Woit and the physicist Lee Smolin, however, the search for beauty is ruining physics. Their ire is directed at "string theory," a magnet for physicists because it is so, well, beautiful, and has such great promise for solving what might be the central mystery of the universe - the incompatibility between the two grand laws that describe everything we know.

Quantum theory - which explains the subatomic world with exquisite precision - reveals that at close range, matter, energy and motion are a choppy mosaic of jittery bits. Think the pointillist painter Georges Seurat on a triple espresso. Einstein's theory of gravity, which describes the large-scale cosmos with exquisite precision, tells us that space and time are woven into a smooth, seamless surface that warps under the influence of massive objects - a universe painted by Salvador Dali. Where the two realms meet, the quantum jitters shatter the glassy surface of space-time like a child cannonballing into a pool.

String theory is the first approach that seems to bring the two together naturally, and such unification of opposites, like electricity and magnetism, has driven physics for more than a century. Simply put, string theory does this by replacing point-like particles with tiny strings of some fundamental stuff vibrating in 10-dimensional space - their harmonies creating everything from quarks to galaxies. The loops of string don't let anything get small enough to let quantum fidgeting rip space and time apart.

String theory has its troubles, which the authors analyze in great and sometimes lucid detail: It appears to be untestable because the strings are too small to be seen, and recent research suggests that the theory could have an infinite number of solutions, so it can't make predictions. And string theory is so ill-defined that even ardent supporters admit they don't know what, exactly, it is. This is why Woit calls the theory, and his new book, "not even wrong," a play on a put-down by the late physicist Wolfgang Pauli.

These issues are well worth addressing, which makes it all the more disappointing that Woit, and Smolin in The Trouble With Physics, write mostly about how string theory has ruined their careers - and physics as well. It has "choked off" investigation of "equally promising approaches," Smolin says. It is a "cult" in which "believers don't care about evidence." Physicists who don't work in string theory are rejected and shunned. "The ability to do mathematically clever work ... [is] valued over the possession of original ideas," he complains. As for beauty, he writes that "elegance" is irrelevant, and "more sober minds" should insist on "a connection to reality."

Although Smolin's book is fairer and far more readable, both suffer from an overflow of jargon. And their language is telling: String theory is described as a "fad," "fashion" or "trend," its culture as "brash, aggressive and competitive." String theorists "swagger." References to Smolin's kind of physics, on the contrary, are accompanied by words such as "deep" and "thoughtful."

Smolin is a respected physicist, having earned a doctorate at Harvard University and written several delightful popular books, including The Life of the Cosmos and Three Roads to Quantum Gravity. He helped found the Perimeter Institute in Waterloo, Canada, as well as a perhaps promising theory called "quantum loop gravity." He's also a former string theorist, so his book is well-informed.

Woit is a different story. As a postdoctoral fellow at the State University of New York at Stony Brook, he couldn't find another position because, he says, he wasn't working on string theory. Woit then moved to Harvard, where the physics department "let me use a desk as an unpaid visitor." He's now a math lecturer at Columbia University.

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