In the absence of a robust coherent connection between the spacetimes of large- and small-scale regions, there has been a reassertion, in the latter, of Newtonian science of gravity in cosmology and astrophysics \cite{Chisari_2011,Chisari_2011a}. For, at small scales, it is apparent that Newtonian science of gravity is normatively applied in analysis and so in simulations. So, though based on Einstein’s theory of gravity, modern cosmology was, in small-scale regions, mainly applying Newton’s methods against the background of a flat spacetime. This occurs even though Newtonian physics had already been proven incapable of explaining certain subtle gravitational effects such as the precession of the orbits of planets and the deflection of light around massive bodies that were explained by general relativity (GR) in \cite{einstein1952}.
Yet, however contradictory the situation appears, it is quite comprehensible. For, in GR, orbits require inherently curvilinear spacetimes \cite{einstein1952}. So, in GR, orbits are inexplicable in the currently applied FLRW spacetime since the latter may, simply by means of a time coordinate transformation, be shown to become, thereby, a Minkowskian flat spacetime. So, orbits cannot be explained in the GR-derived FLRW theory of a spatially flat universe. However, since Newton’s science of gravity applies only to flat space and, moreover, is the only full-fledged alternative to Einstein’s, then its reassertion is fundamentally unavoidable in FLRW cosmology.
So, at these small scales, the current concordance model of cosmology (ΛCDM), in effect, pairs Newton’s science of gravity with the hypothetical cold dark matter (ΛCDM). Even the application of gravitational lensing techniques, based on GR, serves mainly Newtonian objectives of determining mass distributions and potential functions. Here, Newtonian methods are said to yield similar outcomes as Einstein's.
At large-scale, ΛCDM proposes the cosmological constant Λ \cite{Riess_2001} as the DE of the expansion. It is proposed to be a vacuum quantum field of a nature that, via a reflex of the gravitational field, expands space.
So, at small scales, the field is absent and at large scales, its role, in ΛCDM cosmology, is secondary. Yet, classical – that is, pre-FLRW – GR, as a theory of gravitation, is distinguished by the central role of a metric gravitational field – as the only entity that couples both with space and matter \cite{einstein1952}. So, the absence of the gravitational field, or its secondary role, in ΛCDM appears as peculiarities of potentially fundamental impact within a GR-derived theory.
It is here proposed that the passivity, in ΛCDM cosmology, of the gravitational field is the basis of the persistence of the mysteries of DE and DM.
So, the endeavour, here undertaken, is to develop a unitary explanation, within the paradigm of the gravitational field theory of GR, that explains both sets of phenomena. The intent is to include the universal empirical element of the Hubble expansion of space \cite{Riess_2001} within a strictly classical GR explanation that treats all matter generically as energy tensors, while generally ignoring other aspects of the various species of matter and radiation, some of which become so important in ΛCDM astrophysical cosmology.
In §2, a generalized FLRW metric determines certain common dynamic attributes of the associated class of fields. In §3, a gravitationally perturbed Robertson-Walker (gpRW) metric is used to develop descriptions of initial states of certain spherically symmetric gravitational systems. Then, in §4 a physical derivation of the Hubble-Lemaître law is presented. Phenomena associated with DM are explained by the Hubble expansion in §5. The recession in cosmic voids is explored in §6. In §7, the Hubble expansion across all scales is explored. In §8, the redshift-distance relation is explored. In §9, a gravitational process proposed to energize the spatial expansion is presented. In §10, there is a discussion of the views presented here and certain aspects of ΛCDM. The explanations given here are summarized in §11.
\cite{Demianski_2017}. \cite{Harrison_1993}
\cite{Plaga_2005}.
\citep*{Karachentsev_2009}
\cite{Hu_2003}