Expansion Freedom Theory (EFT) v6.8: Gravity as an Inertial Effect of Differential Space Expansion

Newton's first law states that a body in uniform motion continues indefinitely — but offers no mechanism. This unexplained axiom is the entry point of Expansion Freedom Theory (EFT). EFT proposes that velocity is a ratio (an angle between displacement and time), and that ratios are preserved by universal expansion — the conformal effect. Inertia is therefore not a primitive axiom but a direct consequence of the universe expanding. Reversing the argument: the very existence of inertial motion is everyday observational evidence that the universe expands. From this single foundation EFT derives gravity as expansion parallax — the lag ε = GM/rc² between space expansion and matter that cannot freely follow — and unifies the equivalence principle, constancy of c, conservation laws, galactic rotation curves, and cosmic acceleration without invoking dark matter, dark energy, or a graviton. A key conceptual clarification is introduced: space expansion operates on three distinct layers. Basic expansion is universal but hidden by the conformal effect — its local trace is inertia itself. The Hubble law v = Hr is not the speed of expansion but the spatial distribution of accumulated expansion difference between two points. Redshift is the wavelength imprint of this accumulated difference during a photon's journey, not a Doppler shift. The theory further explains galactic rotation curves through a Bernoulli-type conservation of expansion freedom: the flat geometry of spiral galaxies suppresses vertical expansion freedom, which is compensated by enhanced rotational freedom in the disk plane. This mechanism naturally accounts for why spiral galaxies exhibit anomalous rotation curves while elliptical galaxies do not, and provides a geometric interpretation of the γ parameter in Mannheim's conformal gravity, which varies by four orders of magnitude across galaxy types.