Recent Gaia DR3 observations of the Milky Way indicate a Keplerian decline in rotational velocity beyond 19 kpc, challenging standard dark matter models. We present a framework in which the vacuum is modeled as a Quantum Superfluid Substrate (QSS), with galactic rotation emerging from quantized vortex excitations. Gravity arises from the logarithmic nonlinearity of the substrate, reproducing the Baryonic Tully–Fisher Relation without additional dark matter. The observed outer decline corresponds to the termination of the coherent superfluid excitation, providing an explanation for galactic rotation curves.
Alex Smith (Fri,) studied this question.