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We propose that the dark energy driving the present cosmic acceleration originates from the decay and partial freezing of curvature stress generated during both the primordial epoch of spacetime and subsequent high-curvature astrophysical events. Within a nonlocal geometric framework, spacetime possesses an intrinsic curvature-memory field Δμν\Delta_{\mu\nu}Δμν, defined through a causal kernel that integrates the past curvature history. Extreme curvature fluctuations—arising during the Big Bang, inflation, black-hole formation, or other violent astrophysical processes—load spacetime with geometric stress-energy. As the Universe evolves, this stress undergoes temporal decay governed by the relaxation law

τ0 ∂tΔμν+Δμν=Sμν[R],\tau_0\,\partial_t \Delta_{\mu\nu} + \Delta_{\mu\nu} = S_{\mu\nu}[R],τ0∂tΔμν+Δμν=Sμν[R],

where τ0\tau_0τ0 denotes the curvature-memory timescale and Sμν[R]S_{\mu\nu}[R]Sμν[R] represents the curvature source functional. Most of the stored curvature energy dissipates through this decay, while a small isotropic component remains frozen as a residual geometric tension. This residue behaves as an effective cosmological constant with equation of state w≃−1w \simeq -1w≃−1, producing the observed late-time acceleration.

Analogously, just as a stretched fabric rebounds after a heavy object is removed, spacetime itself tends to relax back toward its uncurved state after intense curvature events. During this relaxation, the gradual release of curvature stress-energy acts as a transient driving source of cosmic expansion. The current acceleration may therefore represent the lingering geometric afterglow of curvature relaxation—a persistent remnant of stress-energy released during both primordial and astrophysical curvature decay throughout cosmic history.