Causal Memory Gravity I: Cosmological Baseline and Reduced Almost-Λ Dynamics

Abstract

Cosmic expansion tests whether gravity responds only to present curvature or also retains a fading record of earlier curvature. Causal Memory Gravity (CMG) explores the second possibility through a retarded curvature response that preserves the appropriate General Relativity limits. Causal Memory Gravity I develops this cosmological baseline and its reduced almost-Λ dynamics. The gravitational memory sector is represented by (□ + βrate²)U = −R, with ηact = −α̃, and is studied through FLRW evolution, stability, recombination control, linear growth, and late-time expansion. Observations currently probe a distinct fixed-background closure, μ(k,a) = 1 − ηcl a²βIR²/(k² + a²βIR²), γ(k,a) = 1, where βIR = βrate/c. The action amplitude ηact and observational amplitude ηcl remain separate until a matched background-and-perturbation calculation relates them. For the stated retarded initial data and βrate = H0, the homogeneous calculation gives ηact ≲ 0.04. The DESI DR1 analysis gives Ag = 0.9962 ± 0.0437, consistent with General Relativity at 0.086σ, with large-β fixed-background limits ηcl ≲ 0.015–0.032. The reduced condensate contains a damped almost-Λ branch approaching wDE = −1, with its detailed evolution determined by excitation history. Recent C2 work has validated an action-level scalar prototype that carries gravitational slip. A production perturbation provider is the next step toward connecting the action, cosmological observables, and nonlinear screening within one physical model. For the full CMG corpus, theory map, and related materials, visit: https://cmg.beogradpc.com/