"SST Addendum — He-3 Reinterpretation and Derivation of the Semifluid Density"

This technical note is a supplement to the Spatial Semifluid Theory (SST) and addresses two points that required clarification following external review. 1. He-3 reinterpretation. Primordial He-3 is reinterpreted as a product of a local phase transition induced by pressure fluctuations of the semifluid under Big Bang conditions — not a constituent of the semifluid itself. This removes a structural vulnerability in the original formulation without altering any core prediction. 2. Derivation of the semifluid density. The density rho_sf is derived directly from observational data without free parameters, using spherical geometry and a fixed stellar mass-to-light ratio (ML = 0.5 at 3.6 micron, Schombert et al. 2021): ρ_sf = V² / (4π · G · R²) The factor 4π enters from the total solid angle of the sphere — a geometric invariant, not an assumption. Validated on 87 SPARC galaxies (Q=1): r = +0.823, p = 1.4×10⁻²². The same formula applied to merging clusters (Bullet, MACS J0025, Abell 2744) yields the same order of magnitude, confirming ρ_sf as a property of the cosmic semifluid. AGC 114905 (zero dark matter, isolated) is predicted automatically: N_rot = 2.17 < √4π → vortex not formed → ρ_sf ≈ 0 → pure Newtonian dynamics. All core predictions of SST remain unchanged.