Black Holes and Elastic Spacetime: Higher-Dimensional Reservoirs and Cosmic Acceleration

We develop an elastic higher-dimensional formulation in which black holes absorb not only matter and radiation but also spacetime. The absorbed content is transferred into a finite hypercubic reservoir, accumulating as elastic stress-energy and entropy. We construct the unified action, field equations, horizon flux matching, and the cosmological coarse-grained limit with a matter→elastic transfer Ψ(a). At background level this channel modifies the Friedmann equations and can generate late-time acceleration; at early times a transient activation is equivalent to Early Dark Energy (EDE), reducing the sound horizon. We derive linear perturbations with transfer, entropy inequalities, and junction conditions consistent with the membrane paradigm, and discuss observational signatures in H0, rs, AL, growth, and ISW.