Over the weekend, David Gross, the director of UCSB’s Institute for Theoretical Physics, celebrated his birthday with a few good friends.
Those friends include world-renowned theorists like Stephen Hawking, Edward Witten and Paul Steinhardt, and the party was a gathering of international physicists at the ITP.
The weekend meeting, called “Heterototic Dreams and Asymptotic Visions: The 60th Birthday Celebration for David Gross,” featured speakers on topics such as black holes, string theory, M-theory and inflation theory.
“It’s custom when an important scientist turns 60 to have a conference in his honor,” said physics Professor Joseph Polichinski, who introduced Gross, Hawking, Witten and Steinhardt at a press conference Friday. “David is a particularly important scientist, and so we have a remarkably important and creative group of scientists here.”
The three-day conference was a chance for an international group of physicists to share ideas on the latest in research and the promise of string theory – a set of five theories that could provide a unified explanation for all the forces and matter in the universe.
String theory claims that tiny, one-dimensional strings make up everything in the universe, as opposed to the standard theory that says the universe is made up of tiny point particles like quarks and electrons. The strings in string theory vibrate at different levels, which results in different forces or states of matter.
Under the standard model, a great dilemma arises: Quantum mechanics and general relativity, two of the most fundamental theories in physics, cannot both be right. Because of the nature of strings, string theory would resolve this problem.
Gross said an experiment in early February could help solidify the theory of supersymmetry, which is an important part of string theory. The experiment at Brookhaven National Lab in New York showed a slight anomaly in the value of the magnetic moment of a muon – a particle similar to an electron, but much heavier – a value which physicists had calculated to the 10-billionth place.
“I think there’s a very good chance they’ve discovered an anomaly,” Gross said. “If that’s the case, it’s one of the most remarkable discoveries of the last two decades.”
Results like these have given string theorists hope that their theory will emerge as the unifying theory of the universe. There are, however, five string theories, each subtly different from the other. Gross, along with a group of researchers at Princeton, discovered one of these, called heterototic string theory, in 1984. To unify these five theories, physicists have come up with another theory, called M-theory.
“String theory has heavy merits, but we have come to realize it can’t be the whole picture,” Hawking said. “Instead, there seems to be a network of theories that look very different but are related by what are called dualities, so they describe the same physics. We know that supergravity and the five string theories are physically equivalent under different approximations of the fundamental theory, which we call M-theory. So, in a sense, we have found the ultimate theory.”
M-theory is still in its infant stages, however, and Hawking said he does not see resolution in the near future. The weekend conference, which drew together most of the originators of string theory, sought to give researchers a chance to work toward that end, as well as an opportunity to present new information about the fundamental principles of the universe.
“One had the feeling that somewhere in those talks there was the answer,” Polichinksi said, “if one just knew which sentence to pick out from all the rest.”