Mass-Driven Cosmic Expansion: A Non-Metric Theory of Universe Growth via Intrinsic Mass Generation

We introduce Mass-Driven Cosmic Expansion (MDCE), a novel cosmological model that attributes observed redshift and large-scale dynamics to an intrinsic, exponential increase in the universe’s mass-energy content, rather than metric expansion of spacetime as in the $\Lambda$CDM model. In MDCE, cosmic structures remain at fixed comoving coordinates, with redshift arising from photon energy loss due to deepening gravitational potentials driven by a time-dependent mass scalar field $\mu(t)$. We develop a covariant field theory, derive modified Friedmann-like equations using a time-varying cosmological term $\Lambda(t)$ to balance the static metric with a dynamic stress-energy tensor $T_{\mu\nu}^{(\mu)}$, and demonstrate consistency with observations, including Type Ia supernova distances, CMB angular power spectra, and the Hubble tension. Numerical N-body simulations with dynamic mass injection reproduce large-scale structure and redshift-space distortions. The model ensures local energy-momentum conservation via a generalized continuity equation and is reproducible with open-source tools. MDCE offers a falsifiable alternative to metric expansion, addressing cosmological tensions while aligning with key datasets.