We present Entropic Relativity (ER), a metrological closure framework in which late-time cosmological observables separate into operational classes (null-geometry distances, clock-based rates, lensing, and growth) whose mutual consistency is governed by a single horizon response function (z). ER introduces a two-frame kinematic structure, g_=e^2g_, in which null geodesics are described by a pattern metric g_ while massive clocks accumulate proper time dt₇ₘₒ=e^dt. The framework is tested by an overconstrained closure protocol: (z) inferred from lensing predicts both clock-rate deformations and the growth history through fixed maps. We sketch a thermodynamic ansatz, the Local Entropic Extremum (LEE), which yields a simple power-law envelope (z) =ₘ (z) ^2₄₅₅/3 (for the benchmark =12) with an automatic late-time turn-on. Using a representative late-time suppression ₀ 0. 9, ER predicts an O (5\%) rate inflation H₀^phys/H₀₀^-1/2 and a correlated suppression of lensing and growth under the no-slip restriction =. Within the fixed-background closure implementation used here, a decoupled modification (0 across a broad grid. This yields an order-unity KMS susceptibility C_ 2 (a₀/c H₀) =O (1), sharpening the “a_* cH₀” target into a quantitative calibration. ER reduces the number of independent late-time dark-sector response functions by treating lensing, growth, and clock-rate discrepancies as different operational projections of a single horizon response, while identifying the galactic RAR scale a_* cH₀ as an external consistency target. The primary contribution of this work is methodological: a sign-audited, overconstrained closure protocol that can be applied to present and future datasets to falsify (or support) a one-function horizon-response hypothesis.
John C. Anderson (Sat,) studied this question.