Copy-Horizon Cosmology from Quantum Information Copy Time: An Operational Infrared Cutoff for Holographic Dark Energy with Testable Signatures

We present a strict, non-circular formulation of a “copy-horizon” infrared (IR) scale Lcopy(t) defined operationally from a quantum-information copy time τ_copy(L, t) by the single criterion τ_copy(L_copy(t), t) = H−1(t). The definition requires only mild locality/monotonicity assumptions and does not postulate an a priori cosmological IR cutoff (such as the future event horizon). We then combine this operational IR scale with the Cohen–Kaplan–Nelson (CKN) gravitational collapse bound to obtain the L−2 energy-density scaling as a consistency constraint, and we formulate “saturation” as a falsifiable mechanism with a severe inequality c_Q(z) ≤ 1. We derive the minimal background consequence w_Q(t) = −1 + (2/3)(L̇_copy/(HL_copy)) and show how a hydrodynamic realization of τcopy yields rigid consistency relations linking expansion, growth, and transient time-of-flight observables.