String theory

Summary

String theory is a framework of physics in which the point particles of quantum field theory are replaced by one-dimensional strings. A string moving in spacetime sweeps out a surface, its worldsheet. In perturbation theory the dynamics of the string is a two-dimensional conformal field theory on this surface. The vibration modes of a string appear as particles. One of them always has the properties of a graviton, so the theory includes quantum gravity. Consistency fixes the dimension of spacetime: $26$ for the bosonic string and $10$ for the superstring. String theory has had a large influence on mathematics, for example through mirror symmetry, vertex operator algebras and the AdS/CFT correspondence.