unified field theory

Collective designation for Einstein’s unsuccessful attempts to formulate a theory in which gravity and other interactions, notably electromagnetism, are described in a unified manner – a theory in which gravity and electromagnetism would be no more than different facets of one and the same underlying structure, in the same manner in which magnetism and the electrostatic force are facets of a more general description of electromagnetism.

After Einstein, quite a number of scientists have searched for a unified description of all interactions; the best-known modern incarnation of the idea of unification is string theory.