In the concept of general relativity gravity is the space-time geometry. Again, a relation between electromagnetic field and gravitational field is expected. In this paper, space-time geometry of electromagnetic field in the system of photon has been introduced to unify electromagnetic field and gravitational field in flat and curvature space-time.
International Letters of Chemistry, Physics and Astronomy (Volume 14)
M. C. Das and R. Misra, "Space-Time Geometry of Electromagnetic Field in the System of Photon", International Letters of Chemistry, Physics and Astronomy, Vol. 14, pp. 13-16, 2013