Causal Interaction and the Limits of Observability

This paper develops an information-theoretic framework distinguishing causal interaction from observability. By defining observability in terms of mutual information between physical systems and observers, the work examines conditions under which systems may remain unobservable in principle despite participating in causal physical processes. Examples from cosmological horizons and quantum no-signaling are used to illustrate limits on epistemic accessibility embedded within established physical theories.