Projection-First Reframing of Information, Computation, and Undecidability

This paper completes a projection-first reframing of physics by addressing information, computation, and undecidability. It introduces no new dynamics or empirical claims. Instead, it treats information as a property of effective description—measuring distinguishability under noninjective projection—computation as a diagnostic of descriptive stability and predictability, and undecidability as a structural consequence of finite admissibility. When projection remains admissible, distinctions persist and prediction is possible; when admissibility is exhausted, distinctions collapse, effective evolution becomes noninvertible, and undecidability necessarily appears. This perspective explains why information-theoretic language pervades modern physics, why computational limits arise independently of resources or chaos, and why information loss occurs across measurement, thermalization, black holes, and complex dynamics without violating underlying determinism. Undecidability is shown to be generic and protective: it prevents effective descriptions from requiring impossible foresight about their own future viability. The reframing preserves the empirical success of existing theories while clarifying the structural origin of their limits, completing a unified account in which quantum theory, gravity, information, computation, and irreversibility are coordinated responses to the necessity and finitude of projection in any stable physical description.