Grand Unification Theories (GUT)
Unification of theories about observable fundamental phenomena of nature is one of the primary goals of physics. After Isaac Newton’s unification of gravity and astronomy and the success of the electroweak theory, the process of "unifying" forces continues today. "GUT" models including the strong force predict that the proton is not stable, and are not confirmed. Adding gravity requires to unify quantum mechanics and general relativity into a single theory called quantum gravity,