THE IDIOT,S GUIDE TO PHYSICS

The Idiot's Guide to Incomprehensible Physics Just nod and pretend you understand GRAVITYGravity is the mysterious force that makes all objects with mass attract each other. It explains why apples fall from trees and why you can't dunk. Einstein ascribed it to a distortion of space-time, a theory that holds true as long as you're talking about "big" stuff—from snowflakes on up to the cosmos. THE STANDARD MODELGravity is too weak to explain the strong bonds between subatomic particles. Break gravity, you get NASA. Break the nucleus of an atom, you could get an atomic bomb. Researchers have defined three forces—electromagne­tism, the strong force, and the weak force—that hold atoms together and regulate their decay. The catch is that the theory, known as the Standard Model, can't account for gravity. String TheoryThis is the leading contender for grand unification, a theory that would bring gravity and the Standard Model together into one happy package. It holds that at the core of every subatomic particle there are much, much smaller vibrating entities called superstrings, and that their vibrations form all energy and mass. But the theory also assumes the existence of nine or more dimensions of space, a concept that, so far, renders much of it untestable. E8With 248 individual coordinates, E8 is one of the most complex symmetrical shapes possible. (Many equations can be mapped out geo­metrically; if the math behind E8 were written in newspaper type, it would cover an area the size of Manhattan.) Physicists routinely use shapes to construct theories and probe relationships. Garrett Lisi noticed similarities between the equations of E8 and his own work on grand unification. By plotting particles and forces on various coordinates, he started generating potentially testable results that suggested an underlying mathematical structure to the universe.