Three Roads, One Result: Convergent Derivations of Newtonian, Hydrodynamic, and Tensor Gravitation, and the Case for the Ether Plenum in the Weak Field

This paper consolidates the Theory of NeoGravity and states its case. Its central demonstration is a convergence: three mathematically independent formalisms, Newtonian relativity mechanics, classical fluid dynamics, and Einstein's tensor calculus, are each carried through the classical tests of gravitation, and all three produce numerically identical predictions in the weak-field regime where every existing measurement has been performed. Light deflection at the solar limb yields 1.7516 arcseconds by the fluid and tensor routes against a measured 1.7500 plus or minus 0.0002; Mercury's perihelion advance yields 42.992 arcseconds per century against 42.98 plus or minus 0.04; gravitational redshift, Shapiro delay, and the frame-dragging dipole likewise agree to within observational uncertainty. The convergence rests on a chain requiring no tensor apparatus: matter exchanges mass-energy with a space-filling Ether Plenum, the transport dilutes across spherical shells and returns an inward load by Newton's third law, and the medium settles into hydrostatic equilibrium under that load. Because equilibrium integrates the force rather than reproducing it, the inverse-square load produces a profile exponential in the reciprocal radius, and calibrating a single equation-of-state parameter against the measured deflection determines the medium completely, giving a refractive index equal to the exponential of twice GM divided by the product of the square of light speed and the radius. Every classical result follows from that one expression, and three of the four principal results are independent of the calibration. Because the expression is exact rather than approximate, it yields a falsifiable prediction: expanded in the dimensionless field strength it gives a second-order coefficient of 2.00 against general relativity's 1.75, a difference of approximately 0.23 microarcseconds at the solar limb. The paper states with equal clarity what the framework has not achieved. It carries two fitted constants rather than one, the equation-of-state parameter and the frame-dragging coupling radius, and a companion paper argues these may prove to be a single unknown seen twice. Four problems remain open: the derivation of the equation-of-state parameter from first principles, consistency with precision Lorentz-invariance bounds, the entire strong-field regime, and the polarization content of the medium, on which the framework is presently disfavoured by pulsar timing observations. The paper closes by arguing that the Ether Plenum, defined as a Lorentz-invariant medium rather than the refuted nineteenth-century mechanical aether, has earned reconsideration on grounds of sufficiency, economy, and intelligibility.