Working from principles of differential geometry, physicist Garrett Lisi is developing a new unified theory that purports to explain all the elementary particles, and gravity, in one elegant model. His theory is based on a mathematical shape called E8. With 248 symmetries, E8 is large, complex and beautiful -- and Lisi believes the relationships of its symmetries correspond to known particles and forces, including gravity.

His work, explained in his paper "An Exceptionally Simple Theory of Everything," and in an ongoing discussion on FQXi, is still on science's speculative fringe. But some physicists believe he could be pointing the way toward a truly unified theory.