Quantum Theory of Gravitation vs. Classical Theory

The perihelion-motion of Mercury depends on the fourth-order potential in quantum field theory; it is a “Lamb shift”. In spite of the unrenormalizability of the theory, we have extracted a finite and physically meaningrul quantity, a fourth-order potential, from fourth-order graphs. We have also discussed briefly renormalization of the Newtonian potential in the fourth-order perturbation. The Hamiltonian obtained is the same as the classical one and so it cannot explain the Dicke-Goldenberg experiment. We have calculated fourth-order potential also in Q.E.D.