Dual Boundary Cosmology in the Aether Physics Model: Maximum-Density Closure Walls and Zero-Effective-Density Observation Horizons

This paper develops a dual-boundary cosmology within the Aether Physics Model (APM) and Quantum Measurement Units (QMU). Two distinct limiting boundaries are identified. The first is a physical maximum-density boundary associated with galactic centers and black holes, where local Aether occupancy approaches a maximum allowable state. The second is an observer-dependent observational boundary produced by cumulative local space creation along photon paths. These boundaries are shown to be physically distinct despite often being interpreted as cosmic edges. A dimensionless occupancy coordinate is introduced, =A, where is local occupancy and A is the maximum Aether occupancy. The limiting condition 1 corresponds to saturation and closure, while effective dilution approaches ₄₅₅ 0 at cosmological horizons. The model predicts that every observer naturally appears near the center of a finite observable sphere even though the physical Universe possesses no unique center. The observable Universe is therefore distinguished from the physical Universe. Galactic-center singularities are interpreted as maximum-density closure walls, whereas cosmological horizons arise from the inability of photons to overcome accumulated local expansion over sufficiently large distances. The framework provides a geometric alternative to conventional singularity and horizon interpretations while preserving a finite, bounded Aether structure.