Alice in Wonderland World

Various scenarios or "frameworks" are emerging to describe a mysterious sister world where, as Alice in Wonderland once remarked, "nothing would be what it is, because everything would be what it isn't." Our three-dimensional world includes the coordinates X, Y, and Z, extending infinitely throughout the universe. But, some researchers have proposed that extra dimensions may be finite, and compacted around a sphere, pole, or other geometrical shape. Others have said that quarks, the standard-model particles, may have "technicolor" cousins in another realm. Or, quarks and neutrinos may exist in a mirror-world, as "squarks" and "sneutrinos."

To learn more about what's happening at the very small scale, Maria Spiropulu, a 32-year-old scientist with the Enrico Fermi Institute at the University of Chicago, and her colleagues are staging high-energy particle collisions. Extra dimensions, she explained, would leave behind a "signature," and she hopes to detect it.

The classic signature might be a graviton -- the carrier of gravity-capable, perhaps, of trickling to another dimension. In her experiments, protons (the hydrogen nucleus is a proton) going at almost the speed of light smash head-on into anti-protons. "What comes out," she said, "is a graviton, escaping into an extra dimension, and leaving a viable signature in your detector."

In particle collisions, the conservation of energy and momentum can be measured, so that what goes into the initial experiment must jive with what's left over, post crash-test. "If it doesn't add up and you have significant imbalance," she explained, "that is a viable signal that there is an extra dimension where, if these theories are valid, gravity may become very strong, and other weird properties might kick in. The idea is that there may be a form of super-gravity in the extra dimension."

Spiropulu shared the latest experimental findings at the AAAS meeting, including a completely new-and what she described as "totally innovative strategy" -- worked out by Harvard's Nima Arkani-Hamed and others for "dynamically generating an extra dimension and then testing it," rather than the opposite, more conventional strategy: Searching for proof of an assumed extra dimension.

"We're looking at some really neat, new ideas," she concluded. "We hope by 2005 to have great results on this topic."

-- Ginger Pinholster