iated with Grand Unifica- tion. Supersymmetry could allow a "natural" large hierarchy in energy (and mass) separating the electroweak scale from the Grand Unified scale. That supersymmetry could in principle solve the hierarchy problem, as it has become known, greatly increased its stock with physicists. It

hundred trillion or so galaxies in the visible universe. To explain these features, theorists rely on an idea that arose due to the development of Grand Unified theories. In 1981, Alan Guth realized that the symmetry-breaking transition that might occur at the GUT scale early in the universe might not be id