Abstract Modern cosmology successfully describes the large-scale evolution of the universe through General Relativity and the standard model. Nevertheless, several major observational challenges remain unresolved, including the Hubble tension, the unexpectedly rapid formation of massive structures in the high-redshift universe, and the continued dependence on dark matter and dark energy as observationally indirect components. The Cosmology of Space Elasticity (CSE) proposes that these phenomena originate from treating space as a passive geometric background rather than as a physical medium. In the CSE framework, space is modeled as a continuous viscoelastic continuum possessing intrinsic elasticity and viscosity. This spatial medium should not be identified with the stationary luminiferous ether of classical physics; rather, it represents a localized, spherically symmetric condensation of spatial-medium density mechanically associated with baryonic matter, forming an isotropic local mechanical structure around each mass instead of a universal stationary background. Matter interacts mechanically with this spatial medium through stress transfer, while gravity is interpreted as the macroscopic elastic response generated by spatial density gradients rather than as a fundamental interaction acting through empty space. Crucially, this continuum-mechanical interaction elucidates the physical origin of inertia and acceleration forces, attributing them to the dynamic viscoelastic resistance and structural deformation of the local spatial medium acting against the kinematic acceleration of baryonic matter. Based on this continuum-mechanical interpretation, we derive a generalized CSE field equation that extends General Relativity by incorporating the elastic and viscous constitutive properties of the spatial continuum while recovering the classical Einstein limit under local weak-field conditions. The theory further introduces a distance-dependent effective gravitational coupling, derives a continuum-mechanical explanation for flat galactic rotation curves without dark matter, and proposes a Dual Expansion framework in which the expansion of the spatial continuum and the dynamical response of matter evolve differently over cosmological time. Within this framework, the observed Hubble tension emerges naturally without requiring dark energy as an independent physical component. Finally, the theory establishes a continuum-mechanical connection between microscopic strong-force stress transfer and macroscopic gravitational phenomena, providing a unified physical framework for gravitational dynamics across astrophysical and cosmological scales.
In-Suk Park (Sat,) studied this question.