One of the most distracting features of Einstein field equations of the gravitational field is, due to the appearance of the energy-momentum tensor, the field equations are not purely geometrical. However, it can be shown that this blemish can be avoided if the field equations of the gravitational field are formulated in the same approach as that of the electromagnetic field, in which the energy-momentum tensor is obtained from the more fundamental physical objects, such as the electric and magnetic fields, that obey the more fundamental field equations, such as Maxwell field equations. Please refer to my articleS entitled SPACETIME STRUCTURES OF QUANTUM PARTICLES, A DERIVATION OF THE RICCI FLOW and A TEMPORAL DYNAMICS: A GENERALISED NEWTONIAN AND WAVE MECHANICS posted on ResearchGate for more details.
Working Paper A TEMPORAL DYNAMICS: A GENERALISED NEWTONIAN AND WAVE MECHANICS
Working Paper SPACETIME STRUCTURES OF QUANTUM PARTICLES
Working Paper A DERIVATION OF THE RICCI FLOW