String Theory
String theory is the most promising theory that unifies all particles and forces in nature, including gravity, in a way consistent with the laws of quantum mechanics and relativity. String theory answers fundamental questions about the symmetries of nature, the quantum behavior of black holes, the existence and breaking of supersymmetry, and the quantum treatment of singularities. In string theory all the forces and particles emerge in an elegant geometrical way, realizing Einstein's ultimate dream of building everything from the geometry of space-time.