Two New Books Argue That It Is Time For String Theory To Give Way By George Johnson


by Lee Smolin

Houghton Mifflin, 2006 ($26)


by Peter Woit

When you click the link for the Postmodernism Generator (www.elsewhere. org/pomo), a software robot working behind the scenes instantly throws together a lit-crit parody with a title like this: "Realities of Absurdity: The dialectic paradigm of context in the works of Fellini." And a text that runs along these lines: "In a sense, the main theme of the works of Fellini is the futility, and hence the stasis, of precapitalist sexuality. An abundance of deconceptualisms concerning a self-falsifying reality may be revealed."

Reload the page, and you get "The Dialectic of Sexual Identity: Objectivism and Baudrillardist hyperreality" and then "The Meaninglessness of Expression: Capitalist feminism in the works of Pynchon."

With a tweak to the algorithms and a different database, the Web site could probably be made to spit out what appear to be abstracts about superstring theory: "Frobenius transformation, mirror map and instanton numbers" or "Fractional two-branes, toric orbifolds and the quantum McKay correspondence."

Those are actually titles of papers recently posted to the repository of preprints in theoretical physics, and they may well be of scientific worth—if, that is, superstring theory really is a science. Two new books suggest otherwise: that the frenzy of research into strings and branes and curled-up dimensions is a case of surface without depth, a solip-sistic shuffling of symbols as relevant to understanding the universe as randomly generated dadaist prose.

In this grim assessment, string theo-ry—an attempt to weave together general relativity and quantum mechanics—is not just untested but untestable, incapable of ever making predictions that can be experimentally checked. With no means to verify its truth, super-string theory, in the words of Burton Richter, director emeritus of the Stanford Linear Accelerator Center, may turn out to be "a kind of metaphysical wonderland." Yet it is being pursued as vigorously as ever, its critics complain, treated as the only game in town.

" String theory now has such a dominant position in the academy that it is

PATIENCE with string theory may be fraying.

practically career suicide for young theoretical physicists not to join the field," writes Lee Smolin, a physicist at the Perimeter Institute for Theoretical Physics, in The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next. "Some young string theorists have told me that they feel constrained to work on string theory whether or not they believe in it, because it is perceived as the ticket to a professorship at a university."

The counterargument, of course, is that string theory is dominant because the majority of theorists sense that it is the most promising approach—that the vision of oscillating strings singing the cosmic harmonies is so beautiful that it has to be true. But even that virtue is being called into question. "Once one starts learning the details of ten-dimensional superstring theory, anomaly cancellation, Calabi-Yau spaces, etc., one realizes that a vibrating string and its musical notes have only a poetic relationship to the real thing at issue," writes Peter Woit, a lecturer in mathematics at Columbia University, in Not

PATIENCE with string theory may be fraying.

Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law. The contortions required to hide away the seemingly nonexistent extra dimensions have resulted in structures Woit finds "exceedingly complex" and "exceedingly ugly."

Many physicists will take exception to such harsh judgments (three sympathetic treatments of superstrings were reviewed here in April). But neither of these books can be dismissed as a diatribe. Both Smolin and Woit acknowledge that some important mathematics has come from contemplating super-strings. But with no proper theory in sight, they assert, it is time to move on. "The one thing everyone who cares about fundamental physics seems to agree on is that new ideas are needed," Smolin writes. "We are missing something big."

The story of how a backwater of theoretical physics became not just the rage but the establishment has all the booms and busts of an Old West mining town. Unable to fit the four forces of nature under the same roof, a few theorists in the 1970s began adding extra rooms—the seven dimensions of additional closet space that unification seemed to demand. With some mathematical sleight of hand, these unseen dimensions could be curled up ("com-pactified") and hidden inside the cracks of the theory, but there were an infinite number of ways to do this. One of the arrangements might describe this universe, but which?

The despair turned to excitement when the possibilities were reduced to five and to exhilaration when, in the mid-1990s, the five were funneled into something called M Theory, which promised to be the one true way. There were even hopes of experimental verification. A piece I wrote around that time carried this now embarrassing headline: "Physicists Finally Find a Way to Test Superstring Theory."

That was six years ago, and to hear




Smolin and Woit tell it, the field is back to square one: recent research suggests that there are, in fact, some 10500 perfectly good M theories, each describing a different physics. The theory of everything, as Smolin puts it, has become a theory of anything.

Faced with this free-for-all, some string theorists have concluded that there is no unique theory, that the universe is not elegant but accidental. If so, trying to explain the value of the cosmo-logical constant would make as much sense as seeking a deep mathematical reason for why stop signs are octagonal or why there are 33 human vertebrae.

Most theorists reject this postmodern fatalism, hoping for the breakthrough that points the way to the mountaintop. Gathering in Beijing this summer for the Strings 2006 conference, they packed the Great Hall of the People to hear Stephen Hawking declare: "We are close to answering an age-old question. Why are we here? Where did we come from?"

The answer, they hope, is not "Just because." S!

George Johnson's books include Fire in the Mind: Science, Faith, and the Search for Order and Strange Beauty: Murray Gell-Mann and the Revolution in 20th-Century Physics. He resides on the Web at

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