As the electromagnetic field is characterized by an antisymmetric rank-2 tensor, there is an obvious possibility for a unified theory: a nonsymmetric tensor composed of a symmetric part representing gravity, and an antisymmetric part that represents electromagnetism.
Research in this direction ultimately proved fruitless; the desired classical unified field theory was not found.
In its original form, the theory may be unstable, although this has only been shown in the case of the linearized version.
This led Moffat to propose metric-skew-tensor-gravity (MSTG),[5] in which a skew symmetric tensor field postulated as part of the gravitational action.
STVG, like Milgrom's Modified Newtonian Dynamics (MOND), can provide an explanation for flat rotation curves of galaxies.