This project presents a kinematic audit of 135 disc galaxies from the SPARC database to test the predictions of a bulk viscous vacuum framework against standard dark matter models. The analysis computes the emergent gravity coupling parameter for each galaxy as a function of mean baryonic volume density. The data reveals a critical density threshold at approximately one times ten to the negative twenty-four grams per cubic centimeter where the variance of the coupling parameter reaches a local maximum and bifurcates. An isolated edge-regime population of 27 galaxies at this threshold displays elevated rotational volatility spanning a wide range of coupling values. This density-dependent behavior provides an empirical signature of a phase transition in the vacuum fluid, shifting from a stable laminar anchor in high-density massive spirals to an active kinematic driver in low-density environments. Furthermore, the mean implied viscous acceleration coefficient derived directly from this galactic kinematic data matches the independently calibrated cosmological Friedmann constraint to within 1.2 percent. These findings introduce a bimodal variance structure that static dark matter halo models and modified gravity theories fail to predict, offering a crucial new observational constraint for unified models of galactic dynamics.
Lee Holmes (Thu,) studied this question.