UC Santa Barbara Physicist Advances the ‘String Theory’ : Science: New findings bolster support for a ‘unity in nature’ concept to unravel mysteries of the makeup of the universe.

A physicist from UC Santa Barbara has taken what scientists are calling a major step toward finding a long-sought unified theory of nature. If it works, such a theory would explain everything from subatomic particles to supernovas as different aspects of the same fundamental stuff.

“It’s a major development,” said Edward Witten of Princeton’s Institute for Advanced Studies. “It’s had a very dramatic impact.”

Ever since Isaac Newton discovered that falling apples and orbiting planets are both pulled by gravity, physicists have been hooked on finding unity in nature. If everything could be brought under the same umbrella, then everything would--at least in theory--be understood.

Since Newton’s time, physicists have made great progress bringing pieces of the puzzle together: They found that the lightning that crashes from the clouds is just a different aspect of the magnetism that makes compass needles point north. They learned that undulating waves of light can act like impenetrable pellets of matter.

But they have been stumped in their search for a “grand unified theory” that would unite gravity with the other forces and particles. The only theory that even comes close is known as string theory.

String theory suggests that, viewed under a sufficiently powerful microscope, everything in nature would reveal itself as consisting of tiny vibrating strings. Depending on the way the string squirmed and twisted in space, it would become an electron, a quark, a graviton or some other fundamental building block of nature.

Until now, even string theory could not encompass all of nature. When physicist Stephen Hawking figured out almost 20 years ago that black holes can evaporate, leaving only particle-like dregs, he presented physics with a number of pesky problems. One was that the dregs of black holes--in effect mini-black holes--just wouldn’t go away.

While physicists were confident these black holes were an essential ingredient of nature, they were incompatible with string theory. “The black holes were the fly in the ointment of string theory,” said Andrew Strominger, the physicist who made the discovery along with colleagues Brian Green and Dave Morrison at Cornell.

But now, in a finding that appears to breathe new life into string theory as the underlying source of unity in nature, they have discovered that black holes can transform into strings and vice versa, in the same way as ice changes into water.

If the new finding proves right, then black holes and strings are simply different aspects of the same thing--much as electricity is an aspect of magnetism. And whenever physicists have found similarities hidden amid apparent differences, their understanding of nature has taken a quantum leap forward. For example, the connection between electricity and magnetism revealed that light is the undulation of electromagnetic waves.

Strominger’s discovery was the result of tackling almost unimaginable complexity. String theory is still extremely speculative--the strings, like the mini-black holes, are worlds beyond the power of even the keenest imaginable microscopes.

In addition, the theory only works when the strings vibrate in 10-dimensional space. Three of those dimensions are the familiar north-south, east-west, up-down. The fourth is time.

That leaves six “extra” dimensions to worry about. A theory that works in 10 dimensions isn’t very useful if it can’t be translated into the familiar four dimensions of the physical world. To get from theory to reality, says Strominger, “we have to get rid of those extra dimensions.”

So far, physicists have done this by imagining that the six extra dimensions are so tightly curled in on themselves that they disappear. “If you look at a garden hose from very far away, it looks like a straight line,” said Green, who is still in Italy at the conference where the finding was announced. “But if you look at it from close up, you can see that it has another dimension curled up around it. We suspect the same is true of the universe.”

Unfortunately, there are tens of thousands of ways for the extra dimensions to curl.

Strominger simplified the problem by discovering a mathematical link among all those ways of curling. It is this link that enables black holes to transform into strings, and vice versa. The transformation is similar, he said, to the “phase change” that transforms water to ice.

“Water and ice are both descriptions of H2O in different circumstances,” Strominger explains. “When you understand that, they are not as different as they initially seem.”

“This is extremely exciting,” he said. “It means there is no real distinction between the strings and the black holes. They are just different descriptions from different viewpoints.”

Strominger’s finding was announced last week at a meeting of string theorists in Trieste. It was only one of what Witten calls an “explosion” of findings in the field.

For example, Indian physicist Ashoke Sen, visiting at Caltech from the Data Institute in Bombay, presented what Witten called a “beautiful” calculation showing black holes behaving just like elementary particles. If string theory is right, says Sen, particles such as electrons would ultimately be the same thing as black holes. “There are a lot of exciting developments.”

Still, Strominger cautions that “we are a very, very long way from being able to test string theory. But this is definitely a step in that direction.”