Searching for Extra Dimensions and the Ultimate Theory

At the Large Hadron Collider in Europe, the discovery of the century could start with nothing.

When physicists begin smashing protons together at unprecedented energies over the next year, they will look to see if energy and momentum vanish suddenly from their detectors. That disappearing act might signal that they have created "dark matter," invisible particles that only weakly interact with normal matter.

Some 80 percent of the mass in the universe is thought to consist of