FSDV v3.0 - Four-Dimensional Viscous Substrate: Q=0 Cold Nodes as Dark Matter, Anomalous Heat Flow, Macroscopic Superposition and Directional Vacuum Transport

FSDV models 3D space as emergent from a 4D viscous substrate. Q is substrate vibrational energy.Q=0 nodes are gravitationally active but electromagnetically undetectable, interpreted as transientdark matter. This v3 integrates 2025-2026 experimental results: (i) quantum anomalous heat flowfrom cold to hot via quantum correlations [Advanced Quantum Technologies 2025], (ii) many-bodydynamical localization where driven systems refuse to heat [Science 2025], (iii) macroscopicsuperposition of 5k-10k atom sodium nanoparticles with macroscopicity 15.5 [Nature 2026], (iv)tetraquark family X(6600/6900/7100) showing substrate allows exotic bound states with JPC=2++[CMS 2026], (v) GW170817 constraint on G variation (-3.36 to +0.534 ppb/yr) proving substratestability [Communications Physics 2026], (vi) 300 TeV photon from GRB 221009A surviving via ALP+ Lorentz Invariance Violation, interpreted as Q=0 transit [PRL 2025]. We propose directionaltransport of Q=0 nodes via single-photon Q-gradient impulse, analogous to optical tweezers andthermophoresis, as testable propulsion mechanism.