The Duality of Time Theory

The gravitational field and the electromagnetic field are the only two fundamental fields in nature that have infinite range, and a corresponding classical low-energy limit, which greatly diminishes and hides their particle-like excitations. In 1905, Einstein attributed particle-like and discrete exchanges of momenta and energy, characteristic of field quanta, to the electromagnetic field. His principal motivation was to explain the thermodynamics of radiation, but although the photoelectric effect and Compton scattering strongly suggest the existence of the photon, it might alternatively be explained by a mere quantization of emission.