Conference challenges space-time theory

Those who filed into room A1 of David Rittenhouse Laboratories on Monday entered a new dimension.

Guests filled the large auditorium to capacity to hear Harvard University physics professor Cumrun Vafa speak about string theory as part of the String-Math 2011 conference held this year at Penn.

The weeklong meeting unites mathematicians and physicists from all over the world, some coming from as far as Japan. Next year’s conference is already set to take place in Germany in June 2012. All came to debate the underlying math behind string theory, a cutting-edge area of physics research.

“We are experiencing an ongoing revolution linking geometry and physics,” Vafa told the room, as well as those watching the live stream of the event.

String theory requires the invention of completely new math, specifically special geometry that gives the universe 10 dimensions — rather than the familiar four of space-time. But, Vafa said with a smile, “this is precisely where the fun starts.”

Meng-Chwan Tan, a National University of Singapore professor, agreed. “The most exciting part is the fundamental link between pure geometry, the way things are shaped and connected, and physics, two fields that come from different places” and were completely unrelated, he said.

But why string theory? Vafa explained that when different laws of physics such as Einstein’s general relativity and quantum mechanics are combined, “disaster happens” and nothing makes sense.

But “strings come to the rescue,” allowing new combinations that describe the universe with “simple elegance,” paving the way for breakthroughs like quantum gravity.

However, the theory is not without skeptics. An audience member raised his hand to ask why string theorists argue for ten dimensions, instead of six or 72.

“Well, strings have one dimension, and time is another. So that’s two. Ten minus two is eight, so I have to explain eight,” Vafa rattled, tongue-in-cheek. “And there are eight because … of supersymmetry.”

So that settles it. And as for alternatives to the mainstream theory, like M-theory, which call for 11 dimensions?

“Well, [M-theory] has a 10-percent error,” Vafa quipped, and the audience erupted with roaring laughter.

Still, string theory remains an untested theory. In fact, strings are extremely small — smaller than a human is to the entire universe, making them out of the reach of any technology.

Vafa is unfazed. Theorists are ambitious, Vafa said. “We try to predict what will happen, even if the labs have not yet been constructed.”

His optimism is shared by String-Math organizer and Penn math professor Ron Donagi. “The goal is for String-Math to become the conference of record for mathematical physics.” Although this is only the first conference in a series, ambitious plans are already underway for the conference to travel to Germany, China and Canada.

As Vafa succinctly put it, “A lot remains to be learned… but it’s hard to deny that something extraordinary is taking place.”

Note: This article was updated from its original version to reflect that Donagi's first name is Ron, not Ronald.

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