On a Phenomenological Approach to Gravity

Applying the theory of sources I consider the consequences of using field theoretical 3- graviton vertex instead of the vertex of general relativity. As an example I look for the lowest nonlinear terms in the exteriormetric of a spherically symmetric body. Themethod suggests that the algorithm of obtaining the metric cannot be reduced to solving the Einstein equation. It also seems that in nonlinear approximation the concept of a test particle moving in external gravitational field can be sustained only for a nonrelativistic particle.