Grand unification theory

Grand unification, Grand unified theory or GUT refers to a theory in physics that unifies the strong interaction and electroweak interaction. Several such theories have been proposed, but none is currently universally accepted. The (future) theory that will also include gravity is termed theory of everything.

GUTs also predict the existence of topological defects such as monopoles, cosmic strings[?], domain walls, and others. None have been observed and their absence is known as the monopole problem in cosmology.