Research: When others bailed out, Caltech professor stuck by string theory, now firmly in mainstream of physics.

By K.C. COLE, Times Science Writer


     It's not every day that a revolution in physics is announced by a ranting and raving guy who gets carried off by two men in white coats. Yet that's more or less what happened to Caltech physicist John Schwarz in the summer of 1984.
     To be fair, the ravings were a prearranged part of a physics "cabaret" put on as pure entertainment at the Aspen Center for Physics in Colorado. But Schwarz used the opportunity to announce a newly discovered mathematical "miracle" that set off a revolution in string theory--sparking a renaissance that continues to this day.
     "Within weeks [string theorists] went from an intellectual backwater to the mainstream of theoretical physics," said Schwarz.
     Certainly, string theory--which views everything in the universe as the combined harmonies of strings vibrating in 11 dimensions--has not been proved. At best, it's far from complete.
     But today it's considered a profoundly important work in progress that is almost sure to play a major role in revamping physics.
     This current matter-of-fact acceptance is amazing to Schwarz, who labored for years on the theory in near obscurity, sometimes facing outright hostility. He takes special satisfaction in displaying an editorial that appeared in the Los Angeles Times in 1988, taking sides with an eminent critic who pondered whether string theorists should even be "paid by universities and be permitted to pervert impressionable students."
     The theory's newfound acceptance "has come as a shock to me," Schwarz said in his office at Caltech, where he very belatedly attained the rank of professor in 1985--13 years after he signed on as a researcher.
     Before his 1984 discovery, Schwarz did give occasional talks on his work at scientific meetings. However, they didn't have much impact on the leaders of the theoretical physics community. "I suspect most of them don't remember I was there," he said.

     Problems Seemed Overwhelming
     String theory, after all, did not look very promising at the start. After an initial burst of enthusiasm for the new idea in the early 1970s, the problems seemed overwhelming.
     For one thing, the theory predicted the existence of a particle that traveled faster than light--an impossibility. For another, it did not include particles of matter, but only particles that transmit forces.
     And it didn't help that the theory at first seemed to require 26 dimensions. "For all these reasons, it looked a little crazy," Schwarz said. Besides, string theory was discovered by accident during efforts to understand how nuclear particles bind together inside atoms.
     Physicists stumbled upon the equations almost by chance. They didn't know what the theory meant or what it was good for. In the mid-1970s, a far simpler theory came along that solved the particle problem without getting tangled in 26-dimensional strings.
     Most physicists left the field of string theory. "They stopped for good reasons," Schwarz said. But "I felt [that] such a beautiful mathematical structure had to lead someplace." So he persisted.
     "John Schwarz led the effort to keep string theory alive," said Columbia physicist Brian Greene recently during a lecture at Caltech.
     Even in the theory's "dark ages" Schwarz made big strides, working first with French physicists Andre Neveu and Joel Scherk, and later with English physicist Michael Green. They figured out how to incorporate the matter particles into the theory, got rid of the faster-than-light particle and brought the number of dimensions down to 10.
     But they still faced a major problem. The theory predicted the existence of another strange particle that didn't make any sense. Try as they might, they couldn't get rid of it.
     "Eventually, we decided to stop trying to get rid of the thing and take it seriously," Schwarz said. In a classic case of looking at what everyone else had seen, but thinking what no one else had thought, he recognized the problem particle as a graviton--a "particle" of gravity.
     Suddenly, string theory wasn't just an ill-fitting theory of sub-nuclear interactions. Once it included gravity, it had the potential to become a theory of all the forces and particles in the universe.
     If string theory is right, Schwarz will have gone Newton one better. While Newton discovered the laws of gravity, and Einstein discovered how gravity works, string theory tells us why gravity exists at all. Gravity appears from the equations of string theory as naturally as chickens hatch from eggs.
     Still, few physicists paid much attention. "The plus was [that] there was no competition," said Schwarz. "The minus was that nobody was interested in what we were doing."
     Schwarz's 1984 breakthrough changed all that. (Although far too technical to be understood by laypeople, the mathematical discovery was considered a major advance by string theorists.)
     From then on, he had a lot of company (and competition) from many top physicists, attracted by string theory's newfound potential.
     Still, he remains a leader in the field. By 1987, he'd won not only a professorship, but a MacArthur Fellowship. And his work had set off what became known as the First Superstring Revolution.
     Schwarz, 57, seems surprisingly normal compared to the theory that's driven much of his professional life. He likes to ride his bike, and hike; his office is clean and uncluttered.
     After getting his bachelor's degree in math from Harvard, he received his doctorate from Berkeley in 1966, but watched the politics from the sidelines. He spent the next several years at Princeton as an assistant professor but never got tenure.
     "I would like to say they made a mistake," he said. "But if you look at who they chose instead of me, they did pretty well," he said, naming several top physicists in the field.
     Every summer for 30 years, Schwarz has gone to Aspen, hiking in the mountains, talking strings. "Theoretical physics is a very portable activity, which is nice," he said.
     In contrast to all this seeming predictability, Schwarz's wife, Patricia, who received a PhD in physics from Caltech last year, is a self-described activist. She combines feminism and physics in a lively Web site (www.superstringtheory.com) devoted to string theory, its history and the science behind it.
     The site "was an act of love," she said. "There's nothing more revolutionary you can do than to get people to love physics."
     The two don't talk physics much at home, she said. She's interested in geometrical approaches to space and time, and he thinks algebraically. "When he starts talking about [exotic kinds of] algebras, I just think, 'Yuuuccckk.' "

     'A Lot of It's Guesswork'
     Today, Schwarz works much as he always did. A lot of it, he says, is simply inspired fooling around. "A lot of it's guesswork," he said, laughing. "Of course, we never say 'guesswork.' We say 'conjectures."'
     That approach fits string theory well, because unlike other areas of physics, it doesn't begin with a well formulated theory that can be mathematically explored. Moreover, strings are much too small to see directly, and string theorists haven't yet figured out ways to detect their presence indirectly in experiments.
     That's a problem for theorists, because experiments can't provide the essential reality check of their work. "Usually, there's a back and forth between theory and experiment," Schwarz said. "But [string theory is] so far removed, we have to sort of go it on our own."
     This year Schwarz has some high-level company at Caltech. Edward Witten of the Institute for Advanced Study at Princeton--perhaps the mostly highly respected figure in string theory--is spending the year in the office adjoining Schwarz's.
     Meanwhile, Witten's wife, physicist Chiara Nappi, is teaching at USC. It's all part of a master plan to link Caltech and USC in a new Center for Theoretical Physics. USC already has a strong group of "stringy" physicists.
     "Our goal is to turn Los Angeles into a center for theoretical physics--focusing on string theory," said USC string theorist Itzhak Bars.

     Dismissed by Some as Pretty Mathematics
     Because many critics have dismissed string theory as so much pretty mathematics, Schwarz and his colleagues are anxious to prove them wrong by finding places where the theory can solve real-world physical problems.
     "String theory has held out great promise ever since it came on the scene," said Case Western Reserve University physicist Lawrence Krauss. "But it's not at all clear that it has absolutely anything to do with the real world."
     The problem at the top of almost everyone's list is why empty space seems to be bubbling over with energy yet has little noticeable effect on the cosmos at large.
     String theory should have a good shot at finding a way out of the paradox, say Schwarz and others, but so far it hasn't produced much.
     "If I knew how [to solve that paradox], I would do it," Schwarz said. "You just try to think of whatever good ideas you can."
     On the experimental front, Schwarz and others believe that indirect evidence for string theory might show up within a few years if a new family of particles is discovered either at the Fermi National Accelerator Laboratory (known as Fermilab) outside Chicago or the Large Hadron Collider, now under construction in Europe.
     The family--if it exists--consists of the "supersymmetric" partners of regular particles. Known as "sparticles," they include squarks (which pair with quarks), selectrons (partners of electrons) and so forth.
     Since supersymmetry is an essential aspect of string theory, the discovery of one or more "sparticles" would be a major milestone.
     In fact, Schwarz has said--only somewhat in jest--that it would be more important than the discovery of life on Mars.
     Meanwhile, string theory continues to grow and evolve. In 1995, Witten sparked the latest revolution, introducing vibrating sheets called membranes and bringing the total number of new dimensions to 11. Known as M theory, the new approach allows not only strings and membranes, but also "blobs" of many dimensions, and a whole zoo of extra-elementary objects--including zero-dimensional points known as zero branes.
     Before M theory came along, there were at least five separate string theories with different configurations of dimensions, and each seemed to have little in common with the others. M Theory showed that all five theories were part of a grander scheme. In doing so, it tied together string theory in a way that gave it credibility.
     The situation is strikingly similar to the state of physics before the discovery of quantum theory--when light seemed to be either waves or particles. Later, it was shown that light--like matter--has characteristics of both waves and particles. Both are different aspects of the same entity--just as vapor and ice are aspects of water.
     In the same way, all the different string theories appear to be aspects of each other--the same theory viewed through different lenses.
     "Eventually, the subject won't be called string theory anymore," Schwarz said. "We don't know what the right name will be."
     One name he hates, however, is "the theory of everything," a term some physicists and most journalists use routinely.
     "That's a phrase I detest," said Schwarz, dismissing it as arrogant.
     More important, he said, it's misleading. Even if string theory turns out to be right, "it still wouldn't make us any wiser about all the other phenomena in the world."
     Roses and clouds and war will remain immune to the explanatory power of strings.
     Still, he'd like to know where the theory is heading. Ultimately, that's what drives him--the sense of going "where no person has gone before." He says "person" quite deliberately.
     "Other species in other solar systems have undoubtedly done it many times," he said, without a trace of irony.
     "When people say, 'So and so was the first to discover this or that,' I say, 'Baloney!' It's probably been done millions of times."