Superstrings

The unification of the four fundamental forces of the universe was one of Einstein's unrealized dreams and scientists hope that string theory can solve the problem. One part of string theory, supersymmetry, proposes that early on in the big bang all of the four forces were the same. So far, scientists have been able to show that the Electric and Weak forces are the same at high temperatures, but it has been difficult to unify the strong force and gravity because it takes even higher temperatures (>10¹⁶ K) before those forces should unify with the others.