Measurement as Horizon Activation

Arc II — Observation Paper 2 Title Measurement as Horizon Activation Zenodo DOI 10.5281/zenodo.18188427 Description This paper reframes quantum measurement as the activation of an operational horizon rather than as wavefunction collapse, branching, or decoherence driven by environmental dynamics. Measurement is defined as the moment when accessible correlations saturate, forcing an irreversible projection of observational structure. Within the finite-accessibility framework, a measurement outcome is not a revelation of a pre-existing value but the stabilization of an inference boundary. Once this boundary forms, further refinement of the measured observable becomes operationally impossible, regardless of improvements in apparatus or control. The horizon is informational, not geometric, and need not coincide with any spacetime boundary. The paper demonstrates that standard features of quantum measurement—outcome definiteness, irreversibility, and apparent randomness—follow directly from accessibility limits without invoking collapse postulates or many-worlds branching. Born-rule statistics emerge as the unique stable weighting compatible with horizon activation and correlation degradation. By treating measurement as a structural transition in accessibility, the work unifies measurement theory with thermodynamic irreversibility and horizon physics. It also clarifies why measurement problems persist when accessibility constraints are ignored. Keywords quantum measurement; wavefunction collapse; horizons; irreversibility; Born rule; operational quantum mechanics Notes Arc II — Observation (core conceptual paper) Measurement defined as horizon formation Collapse reinterpreted as accessibility saturation Born rule emerges structurally Bridges thermodynamics, measurement, and horizons