Foundations of an Eternal Universe—Toward an Eternal Universe Model (I)

We present a new cosmology model---the Eternal Universe Model (hereafter, EU-model)---that emerges from a subtle but consequential modification of the standard Friedmann--Lemaitre--Robertson--Walker (FLRW) framework. At first glance, the EU-model resembles the familiar ∧CDM concordance model; its departure, however, is philosophically and physically decisive: we relinquish the assumption of temporal homogeneity. Specifically, we allow the rate at which time progresses---encoded in the 00-component [g₀₀ = a²_t (r) c²₀ ] of the spacetime metric tensor---to vary systematically with radial position throughout the infinite expanse of the Universe. This single and seemingly banal alteration in the temporal architecture of spacetime gives rise to a remarkably new and rich cosmology. It introduces the continuous creation of matter and energy; it permits the variation of Fundamental Natural Constants (FNCs); it accommodates non-ponderable negative matter as a natural substrate for antimatter; and it endows the Universe with a fixed, absolute spatial centre from which all motion may be referenced. Furthermore, this framework offers natural explanations for the Hubble tension and the Cosmological Axis of Evil. The Universe that emerges is temporally and spatially infinite, globally unchanging, and truly eternal---with no beginning and no end.