Classical unified field theories version of the general-relativistic field equation expressed the property that the universe was "self-gauging". Since the simplest cosmological model (the De Sitter universe) that solves that equation is a spherically symmetric, stationary, closed universe (exhibiting a cosmological red shift, which is more conventionally interpreted as due to expansion), it seemed to explain the overall form of the universe. Like many other classical unified field theorists, Eddington considered that in the Einstein field equations for general relativity the stress–energy tensor formula_1, which represents matter/energy, was merely provisional, and that in a truly unified theory the source term would automatically arise as
Unified field theory formula_7 manifold. In mathematics, if f(z) is a holomorphic function restricted to the Real Numbers, it has the complex conjugate properties of f (z) = f *(z*), which leads to the above equation when formula_21 is satisfied. All four of the known fundamental forces are mediated by fields, which in the Standard Model of particle physics result from exchange of gauge bosons. Specifically the four fundamental interactions to be unified are: Modern unified field theory attempts to bring these four interactions together into a single framework. The first successful classical unified field theory was developed by James Clerk Maxwell. In