‘Brilliant 10’ List Includes Physics Prof

Professor of Physics Nima Arkani-Hamed seeks to find new worlds, explore the far reaches of space, and to boldly go where no man has gone before—all from the confines of his office.

Arkani-Hamed recently made Popular Science’s “Brilliant 10” list in its October issue for his research on the idea that our universe may be only one of many “multiverses” and that additional dimensions may exist.

Arkani-Hamed’s favorite topic of discussion is the Large Hadron Collider (LHC) experiment, a 27-kilometer-long machine that will begin operation in 2007, combining two beams of particles at incredibly high speeds and energy and will help test his contributions to the multiverse hypothesis.

“This experiment is much more important than anything to do with me,” he said. “It’s really going to tell us something fundamental about the world.”

Physicists have tried for years to find the value of the cosmological constant, a number supposedly responsible for keeping particles in our universe stable. But scientists’ calculations always overshoot the actual value. For decades, the issue of how such a finely-tuned constant could exist has puzzled top scholars.

“If any constants of nature were a tiny bit different it would totally disturb the universe,” Arkani-Hamed explained. The theory of multiverses posits that there are many universes with different sets of natural laws—and cosmological constants. Some universes have tiny constants, while others have large constants corresponding to accelerating forces that result in uninhabitable, instable universes.

Arkani-Hamed said that different multiverses might have different, randomly set cosmological constants which would explain the existence of such a specific universal property.

He recently proposed a model for new physics, called split supersymmetry—which theorizes that half of all particles in the universe have partner particles. He said that if the results of the LHC experiment reveal split supersymmetry, “it would be a tremendous push in the direction of a multiverse.”

“Right now a lot of people are on the fence,” about the theory of a multiverse, Arkani-Hamed said. “I think if the LHC sees split super symmetry it’s over.”

In his other work, Arkani-Hamed has theorized that extra dimensions exist, in addition to the three dimensions of space and the fourth dimension of time. He reasoned that gravity only appears to be weaker than other forces—such as electromagnetism—because it is diluted over more space.

If gravity is not weaker than other forces, he said that the effects of string theory could be observed more directly through experimentation, which would put an end to physicists’ studying forces at shorter and shorter distances.

“The fundamental theory that unifies gravity with everything else would not take place at ultra short distances but right above our heads,” he said. He added that there may be gigantic extra dimensions of space if this is in fact true.

Mallinckrodt Professor of Physics Howard M. Georgi ’68 wrote in an e-mail that Arkani-Hamed’s work on split supersymmetry could be just as important as his research on large extra dimensions, but only time will tell. It is possible that the LHC will show evidence that Arkani-Hamed is correct about extra dimensions instead of split supersymmetry.

“Since we don’t know what is going to show up at the LHC, we don’t know what is going to be most important,” he wrote.

—Staff writer Katherine M. Gray can be reached at kmgray@fas.harvard.edu.