The general theory of relativity is the progenitor of this unified field theory. This paper is the culmination of the author's lifelong efforts to unify gravitation and electromagnetism, embodied by SO(3,1) x SO(2) and SU(3,1) x U(1) gauge-invariant generalizations of the general theory of relativity. A unified theory of this kind may be expected to comprise the entire physical reality, from the innermost structure of matter - the ultimate constituents - to the outermost structure of the boundless universe. This version of the unified field theory is unique from those of Einstein and Schrodinger because of the existence of a correspondence prinicple and because of both the geometrical and action principle derivations of its field equations. Furthermore, the duality of the gauge symmetries based on the symmetry groups SO(2) and U(1) yields spin and statistics connections, via a supersymmetry operation, for the half-integral and integral spin systems. The theory also can be cast in the non-Abelian gauge field theory analogous to the Yang-Mills formalism, as shown in Appendix H. In addition to electric charge, the theory yields a new kind of magnetic charge with neutral distributions to constitute elementary particles of half-integral and integral spins. The confinement of magnetic monopoles of infinite varieties into elementary particles is the real reason for their absence in the big bang's pre- and post-primordial nucleosynthesis inventory. The extended and relativistically invariant structure of elementary particles leads to finite values for observables without the renormalization or rescaling of the electric charge and mass. The theory predicts the existence of matter without electromagnetic interactions (and, therefore, without electric charge) as bosons and fermions, violating charge conjugation and parity symmetries. This basis of the theory can be related to the existence of cold, dark matter in the universe. The possibility for the existence of a spectrum of massive neutrinolike particles may yield a clue to the distribution of the ubiquitous dark matter and its abundance over luminous matter. In all these the size of the magnetic and electric charge ratio may play the key role.
The emergence of a superstrong, short-range (approximately 10(-33) cm) gravitational force holding the charges together, hence, acts as a source of the electromagnetic field, just as the electromagnetic field sources a gravitational field, providing a genuine unification of these two fundamental force fields. The superstrong, short-range gravitational interaction may be mediated by massive (approximately Planck mass) gravitons. The G bosons predicted by this theory could decay into four fermions or two bosons, respectively. The field equations have solutions also for spin 2 massless particles, that is, gravitons corresponding to the quanta of the pure gravitational field. The five-component field for graviton is reducible to two states of polarization. The theory provides another example of complementarity relating the spin angular momentum and particle structure. The presence of fractional spin angular momentum and corresponding fractional statistics is somewhat reminiscent of the recently introduced concept of anyons. The concept of photons and localization of energy is defined by the properties of the magnetic charge distribution. The nonlinearity of the photon arises from the coupling of the neutral magnetic current structure of the elementary particle with the electromagnetic wave. The four-momentum of a photon is created as a result of the magnetic charge confinement of the electromagnetic waves over the range of an infinite number of frequencies, weighted over, for each frequency, by the value (including change of sign over the stratified and alternating magnetic charge layers) of the magnetic current density corresponding to that frequency. Thus the four-momentum of the photon is the result of constructing a wave packet confined to (i.e., absorbed or emitted within) the magnetic charge distribution of the elementary particle. Appendix I contains letters received from Einstein, Schrodinger, and Dirac while the author was a graduate student at the University of Cambridge.