A Case for an Inhomogeneous Einstein-de Sitter Universe

Abstract: In our local-to-global cosmological framework, cosmic acceleration arises from local dynamics in an inhomogeneous Einstein-de Sitter (iEdS) universe without invoking dark energy. An iEdS universe follows a quasilinear coasting evolution from an Einstein-de Sitter to a Milne state, as an effective negative curvature emerges from growing inhomogeneities without breaking spatial flatness. Acceleration can arise from structure formation amplifying this effect. We test two realizations, iEdS(1) and iEdS(2), with $H_0={70.24,74.00}\ \mathrm{km\ s^{-1}\ Mpc^{-1}}$ and $\Omega_{\mathrm{m},0}={0.290,0.261}$, against CMB, BAO, and SN Ia data. iEdS(1) fits better than $\Lambda$CDM and alleviates the $H_0$ tension, whereas iEdS(2) fully resolves it while remaining broadly consistent with the data. Both models yield ${t_0\simeq13.64\ \mathrm{Gyr}}$, consistent with globular-cluster estimates.