The NeoGravity Theorem: Gravitational Attraction as a Radiative Undertow Within a Space-Filling Ether Plenum

This paper introduces the founding postulate of the Theory of NeoGravity: that gravitational attraction is not a fundamental force acting between masses, nor a curvature of spacetime, but the mechanical reaction load returned upon matter by a space-filling Ether Plenum that matter itself continuously drives outward, a reaction this series terms the Radiative Undertow. Matter exchanges mass-energy with the Ether Plenum, transporting momentum outward at a rate dp/dt and, because the transported field carries angular as well as linear momentum, exerting a torque density upon the medium as well as a pressure. By Newton's third law the Ether Plenum returns an equal and opposite, inward-directed load upon the emitting body, and this returned load, the Radiative Undertow, is identified with gravitational attraction. Because the returned load is compressive, the Ether Density rises toward the emitting mass, so that the medium is denser near a gravitating body and light traversing it slows, exactly as light slows in glass. Because the outward transport dilutes across spherical shells whose area grows as the square of the radius, the returned load necessarily falls as the inverse square of the distance, so that the inverse-square form of gravitation follows from Euclidean geometry rather than being assumed. The paper is explicit about the limits of this result. Two quantitative constraints are computed here and stated openly. First, ordinary electromagnetic radiation pressure is far too weak to constitute gravitation: the solar radiation pressure force on Earth is approximately 5.79 times ten to the eighth newtons against a gravitational force of approximately 3.54 times ten to the twenty-second newtons, a ratio of order ten to the minus fourteen. Second, the coupling cannot be proportional to thermal luminosity, because the Sun exceeds Earth in thermal output by a factor of approximately 3.13 times ten to the ninth while exceeding it in mass by only 3.33 times ten to the fifth, a discrepancy of roughly four orders of magnitude. The mechanism proposed here therefore couples to the total mass-energy content of a body rather than to its photon output, and the magnitude of that coupling is calibrated by identification with the observed gravitational parameter GM rather than computed from first principles. The paper accordingly claims to derive the form and direction of the gravitational load but not its magnitude, a division of results that parallels Newton's own position, in which the inverse-square law was established while the constant G was determined empirically by Cavendish more than a century later. The paper closes by identifying the specific quantities this postulate supplies to the remainder of the series, principally the outward force density that Working Backward Through the Maze (Guagliardo, 2026, Paper 15) integrates into a hydrostatic equilibrium profile, and by stating the open problem that the magnitude and mass-energy proportionality of the coupling remain to be derived.