What We’ll Find Inside The Atom

What is this dark matter made of? All kinds of candidates have been considered. Could it be small dead stars that don't emit any light? Black holes? Huge planets? Today the origin of dark matter is unknown. Nevertheless, if not for dark matter, galaxies would not have formed and we would not exist. The theory of supersymmetry, if true, predicts the existence of a huge number of new particles, twins to the quarks, leptons, and bosons we have met, including some excellent candidates for dark matter. These would show up in the analysis of LHC collisions.

Where did all the antimatter go? In the 1930s, theorists predicted that every charged particle has an antimatter twin—an electron has a positron; a proton has an antiproton. However, in our galaxies and as far as our wonderful tools can reach, all we can see is matter. Its absence is attributed to a tiny asymmetry: When the universe was created, slightly more matter was made than antimatter. When matter and antimatter collide, they annihilate one another, producing photons—particles of light. Thus, all the antimatter is "consumed" by the matter and what's left over is pure matter and light. The nature of the asymmetry is poorly understood, but the LHC may help us understand it.

Are there more than just the four dimensions (three of space and one of time)? One of the more exciting prospects of the use of the LHC is in finding what are called extra spatial dimensions beyond the familiar breadth, depth and height. Extra dimensions are a feature of string theory, one of the most exciting speculations in science, and one approach to figuring out how to unify gravity and the other forces. It proposes that the world is made of tiny vibrating strings. These vibrations are the particles we have discussed. (If you don't understand that, don't worry: few people can get their heads around string theory.) The existence of extra dimensions is one of string theory's most awesome predictions. Most of these dimensions are curled up so tightly that they are unobservable. In some versions of the theory, gravitational energy leaks out of our three-dimensional system into these hidden dimensions, providing a mechanism for the weakness of the gravity force. Using the LHC, we might discover such hidden extra dimensions by studying reactions where energy seems to disappear (the energy moves along dimensions we can't see). Such a discovery would greatly encourage string theorists. (Oh well, not all discoveries are beneficial.)

This brief summary doesn't come close to naming all the expectations of the LHC in solving the puzzle of the universe. Although the machine is now just starting to do its work, the true sharpness of the LHC "telescope" won't become apparent for the next several years, and its magic will truly unfold through 2020. Certainly we will have answers to questions we know how to ask and, if history is any guide, we will also find answers to questions we have never dreamed of asking. Just as we did with Galileo's telescope.

Lederman won the Nobel Prize for his work in particle physics in 1988. He is currently resident scholar at the Illinois Mathematics and Science Academy, a high school for gifted students.

© 2008