Recent items discussed on Vortex-l have addressed short range effects of a gravitational field on small systems of matter. It seems there should be an association of gravity and spin energy/angular momentum, given the equivalence of mass and energy.
The following link gives a discussion of such a theory: https://en.wikipedia.org/wiki/Einstein%E2%80%93Cartan_theory Note the torsion tensor becomes important in this theory and allows it to act as an independent variable. Also the discussion notes: “Einstein–Cartan theory has been historically overshadowed by its torsion-free counterpart and other alternatives like Brans–Dicke theory<https://en.wikipedia.org/wiki/Brans%E2%80%93Dicke_theory> because torsion seemed to add little predictive benefit at the expense of the tractability of its equations. Since the Einstein–Cartan theory is purely classical, it also does not fully address the issue of quantum gravity<https://en.wikipedia.org/wiki/Quantum_gravity>. In the Einstein–Cartan theory, the Dirac equation<https://en.wikipedia.org/wiki/Dirac_equation> becomes nonlinear<https://en.wikipedia.org/wiki/Einstein%E2%80%93Cartan_theory#cite_note-7> and therefore the superposition principle<https://en.wikipedia.org/wiki/Superposition_principle> used in usual quantization techniques would not work. Recently, interest in Einstein–Cartan theory has been driven toward cosmological<https://en.wikipedia.org/wiki/Physical_cosmology> implications, most importantly, the avoidance of a gravitational singularity<https://en.wikipedia.org/wiki/Gravitational_singularity> at the beginning of the universe.<https://en.wikipedia.org/wiki/Einstein%E2%80%93Cartan_theory#cite_note-NP1-8><https://en.wikipedia.org/wiki/Einstein%E2%80%93Cartan_theory#cite_note-NP2-9> The theory is considered viable and remains an active topic in the physics community.” The difficulty associated with the math that stems from the theory has been a stumbling block in any coupling of spin and angular momentum with potential and kinetic energy in complex systems of matter. The discussion of this theory is extended with the following: http://www.actaphys.uj.edu.pl/fulltext?series=Reg&vol=38&page=2211 IMHO its time that the physics community gets hot on application of this theory to potential energy fields associated with LENR phenomena in nano--systems. The quantization of spin/angular momentum transitions is a key feature to add to the analyses. Good Computers should help in the nonlinear differential equation solutions. Bob Cook