Arc I — Accessibility Paper 3 Title Extreme Blueshift as an Operational Projection Zenodo DOI 10.5281/zenodo.18180789 Description This paper examines extreme blueshift phenomena as an operational projection effect arising from finite accessibility, rather than as a consequence of divergent geometric energy or pathological spacetime behavior. Situations traditionally associated with infinite blueshift—such as near-horizon observers or highly accelerated frames—are reinterpreted as projections of bounded information onto collapsing accessible channels. The analysis shows that extreme blueshift occurs when coordination is forced across regions with rapidly diminishing null accessibility, compressing distinguishability into increasingly narrow observational windows. The divergence appears not in physical energy transfer, but in the operational representation of signal frequency relative to a degrading reference frame. By framing blueshift as a projection artifact, the paper resolves apparent infinities without invoking trans-Planckian physics or breakdowns of effective field theory. The result aligns extreme blueshift with redshift and horizon behavior under a unified accessibility-based description. This perspective clarifies long-standing conceptual issues in black hole physics and accelerated observers, demonstrating that extreme blueshift reflects limits of inference rather than physical singularities. Keywords extreme blueshift; operational projection; horizons; trans-Planckian problem; accessibility limits; null coordination Notes Arc I — Accessibility (operational foundations) Blueshift interpreted as projection under accessibility collapse Resolves trans-Planckian paradoxes without new physics Complements redshift and horizon accessibility framework Sets groundwork for strong-field reinterpretations