We show that in the Schwarzschild vacuum, the Kretschner scalar K = Rₐbcd Rᵃbcd is the unique local, covariant, non-negative measure of gravitational energy density. As a consequence, the GR correction responsible for Mercury's perihelion precession is identically the coupling of the curvature intensity √K with the orbital angular momentum L², in structural analogy with the magnetic Lorentz force. No new physics is introduced; all results are identities within standard General Relativity.
Roberto Pavani (Sat,) studied this question.
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