A Saturation Bound on Gravitational Power from Spacetime Flow

We present a kinematic and geometric argument showing that gravitational interactions admit a universal upper bound on effective power transfer to matter, arising from saturation of spacetime flow velocity at the universal causal limit c. Treating gravity as a spatial gradient—equivalently described by Painlev´e–Gullstrand congruences—we define an operationally meaningful quantity: the effective gravitational power delivered to a freely falling test mass. In weak fields this power reproduces familiar Newtonian energetics, while in strong fields it saturates at horizons rather than diverging. At a Schwarzschild event horizon, where the spacetime
flow speed reaches c, the gravitational power remains finite and scales inversely with black-hole mass. This result demonstrates that infinite gravitational energetics are unphysical and that classical singularities correspond to a breakdown of description
rather than physical infinities. The framework is minimal, conservative, and fully compatible with General Relativity.