String Theory: Try that on for Size, Einstein

How can you not admire someone who isn't afraid to tackle anything--and that surely includes University of California, Berkeley professor Mina Aganagic who has set out to figure out, well, the "theory of everything."

After all, Albert Einstein spent most of his life trying to find a theory of everything, and he couldn't pull it off. He did put forth the theory that linked geometry and physics, which just happens to be Aganagic area of interest and expertise. However, Einstein was stumped by quantum mechanics, which is the point where classical geometry breaks down. And that's where Mina Aganagic steps in.

"The basic question is what does geometry look like at very short distances?" says Aganagic, who holds a joint appointment in the Department of Physics and Department of Mathematics.

The distances that Aganagic deals with are on order of the Planck scale, 10 to the minus 33 centimeters, the smallest unit of space in the universe. That's where geometry, which goes hand-in-hand with physics, fails and string theory emerges.

String theory attempts to unite Einstein's general theory of relativity and quantum mechanics under one umbrella, or "theory of everything," that explains all of the fundamental forces and particles in our universe. According to string theory, all elementary particles are tiny vibrating strands of energy.

"String theory is the only known solution to the problem which is at the core of modern physics: the incompatibility of quantum mechanics and gravity," says Aganagic. "If you could look at them from far away, they'd look like points," she goes on to say, "but if you get close enough, you'd realize that they're really one-dimensional loops."

These loops of string vibrate in 10 dimensions, and every kind of particle and force corresponds to the particular vibrational pattern of a string. While there is no experimental proof yet that string theory is correct, Aganagic says that putting the physics through the mathematical ringer is not entirely unlike experimental verification.

"You could say that what we're discovering is quantum geometry," she adds.

For example, one problem she has investigated, as reported by UC's David Pescovitz, involves calculating the entropy of black holes. According to classical physics, material that falls into a black hole could vanish from our universe entirely, violating the Second Law of Thermodynamics. However, string theory provides a "fantastically clever way of solving the problem," Aganagic says, without violating any fundamental laws of nature.

"Unlike in Einstein's time when the relevant mathematics was already in existence, the mathematics we need now hasn't been fully developed yet," Aganagic says. "This time around, math and physics are being discovered in parallel."

Posted by Jon Erickson at 09:50 AM  Permalink