In physics, a unified field theory, occasionally referred to as a uniform field theory, is a type of field theory that allows all that is usually thought of as fundamental forces and elementary particles to be written in terms of a single field.
There is no accepted unified field theory, and thus it remains an open line of research. The term was coined by Einstein, who attempted to unify the general theory of relativity with electromagnetism. The “theory of everything” and Grand Unified Theory are closely related to unified field theory, but differ by not requiring the basis of nature to be fields, and often by attempting to explain physical constants of nature.
This video describes unified field theory as it is currently understood in connection with quantum theory by Michio Kaku, Henry Semat Professor of Theoretical Physics at CUNY. Kaku has had over 70 articles published in physics journals such as Physical Review, covering topics such as superstring theory, supergravity, supersymmetry, and hadronic physics. In 1974, along with Prof. Keiji Kikkawa of Osaka University, he authored the first papers describing string theory in a field form. Kaku is the author of several textbooks on string theory and quantum field theory.