Cosmological Expansion as a Conditional Necessity for Distinct Relational Scales: Double-Slit Interference, Neutrino Oscillations, Shadow Mass, and Cosmological Horizons in Entanglement–Algebraic Spacetime

This paper is archived as a speculative research work.Physical subjects participate coherently through the source-qualified relationships defining their relational scale. Subjects in distinct scale-equivalence classes lack the scale-defining mutual relatability of subjects within one class. Entanglement–Algebraic Spacetime (EAS) uses this intra-scale coherence and inter-scale separation to investigate how definite physical registrations preserve the consequences of richer source-conditioned organizations. We examine four qualified physical interfaces: double-slit electron interference, neutrino flavor oscillations, Shadow Mass gravitational aggregation, and cosmological horizons. The first two exhibit coherence-sensitive patterns assembled from definite individual detections; the Shadow Mass model represents source-conditioned comparison covariance through a selected and calibrated gravitational interface. The cosmological example asks what permits distinct relational scales to remain differentiated throughout an infinite, future-eternal universe. Under the explicitly proposed scale-to-causal hypotheses SC1–SC2, distinct scale classes in an unbounded populated spatially flat FLRW interface require finite future comoving null reach. The independently certified conditional FLRW horizon theorem then establishes that the scale factor is unbounded on every future tail, with positive expansion and positive acceleration occurring at arbitrarily late epochs. These physical applications use separate source, apparatus, and interface hypotheses; the neutrino replacement and combined four-regime correspondence remain proposed rather than author-certified. The result distinguishes source-faithful registration from individual resolution of every contributing comparison, while maintaining the SF ontology and the mathematical interface representations in their proper roles.