A Covariant Viscoelastic Spacetime with Gravitational Memory

This record is a duplicate created during a versioning error.For the latest and official version of this research (v30 and beyond),please refer to the following permanentlink: https://doi.org/10.5281/zenodo.18911689We propose a covariant gravitational framework in which spacetime behaves as a causalviscoelastic medium possessing gravitational memory. The theory is governed by a universalcoupling constant κ = 0.86 that determines the relaxation of gravitational dynamics towardan equilibrium expansion rate. The total energy–momentum tensor is conserved while allowing energy exchange between baryonic matter and a spacetime memory stress–energycomponent.Cosmological dynamics are described by a relaxation equation in which the Hubble parameter evolves toward an equilibrium response defined by baryonic matter, a non-particlememory energy density, and vacuum energy. The delayed gravitational response naturallyextends the age of the Universe to 15.5 Gyr without particle dark matter, while maintainingstability at high redshift (z > 10).The framework reproduces galactic rotation curves and provides a unified macroscopicdescription of gravitational phenomena based on viscoelastic spacetime dynamics. Generalrelativity is recovered in the short-memory limit.