The Science Behind Final Theory
What Now?
So how will physicists grope their way toward the Theory of Everything? Most scientists believe the answers can be found in violent subatomic events that may be influenced by fundamental physical laws that are detectable only under high-energy conditions. For decades, researchers have been building particle accelerators that can boost protons, electrons and ions to ever higher velocities. By observing the spectacular collisions of these whizzing particles, physicists have confirmed many of the predictions of quantum theory.
The most powerful particle collider in the world is the Tevatron, a giant circular tunnel dug into the grounds of the Fermi National Accelerator Laboratory west of Chicago. The Tevatron is a particle raceway with a four-mile circumference. Superconducting magnets accelerate particles around the track, propelling a beam of protons clockwise and a beam of antiprotons counterclockwise. (Antiprotons have the same mass as protons, but an opposite charge.) The particles are boosted to 99.9999 percent of the speed of light, giving each beam the kinetic energy of a rumbling subway car. When a proton collides with an antiproton, the energy of the impact is two trillion electron volts, which is enough to generate all kinds of exotic particles that can't otherwise be seen.
But an even more powerful machine is coming.
This year scientists at CERN, the European physics laboratory near Geneva, will start operating the Large Hadron Collider, a 17-mile ring that will generate proton impacts with energies seven times higher than the Tevatron's. Physicists hope these collisions will reveal phenomena that go beyond the predictions of standard quantum theory. For example, scientists may find evidence of supersymmetric particles or extra dimensions, which would bolster the case for string theory.
Meanwhile, other scientists are hoping to discover new physical laws by studying the neutrino, which is perhaps the most mysterious fundamental particle. Ubiquitous but maddeningly elusive, the neutrino has no charge and very little mass and appears to oscillate wildly from one quantum state to another as it zips along. Recent results from Fermilab's Booster Neutrino Experiment, which is firing the particles at a huge tank of mineral oil, gave tantalizing hints of new physics. Some theorists speculate that the results were skewed by "sterile neutrinos" that can bounce in and out of the brane of our universe, taking shortcuts through the extra dimensions of the bulk.
For now, the Theory of Everything remains the Holy Grail of physics, appearing only in the ecstatic visions of its seekers. It's not too early, though, to consider whether a unified theory could be dangerous. Could researchers use the theory to build terrible new weapons, in much the same way that the Manhattan Project scientists used Albert Einstein's formulas to devise the atom bomb? If extra dimensions do indeed exist, they may be curled into infinitesimal tubes or manifolds, which would explain why we don't ordinarily observe them. And the extremely curved sheets of spacetime, like tightly wound springs, may hold large amounts of energy. Just as scientists learned to tap into the energy hidden within the uranium nucleus, they may someday discover how to unleash the vast powers contained in the extra-dimensional folds of spacetime. Unfortunately, the possibility can't be dismissed.