SECTOR PAPER XVI — δI–Correlation Waves and the Gaia Disc Oscillation A Substrate‑Driven Interpretation of the Milky Way's Outward‑Travelling

Sector XVI presents the public‑safe phenomenology of δI‑Correlation Waves, a dynamical mode of the Unified Information Substrate responsible for the large‑scale vertical oscillation observed in the Milky Way disc by Gaia. These waves arise from correlation‑geometry gradients within the δI‑substrate and propagate across galactic scales without external forcing. The sector demonstrates how correlation‑driven displacement, phase‑offset structure, disc‑wide coherence, and outward radial propagation naturally reproduce all four defining features of the Gaia oscillation. Classical disc dynamics cannot generate these behaviours simultaneously, whereas δI‑Correlation Waves provide a single, unified, non‑perturbative explanation. This paper establishes the substrate‑level origin of the Milky Way’s travelling vertical wave and forms the first component of the horizon‑proximal collapse chain.