Elucidating the Dark Energy and Dark Matter Phenomena Within the Scale-Invariant Vacuum (SIV) Paradigm

Abstract: The enigmatic phenomenon of dark energy (DE) is regarded as the elusive entity driving the accelerated expansion of our Universe. A plausible candidate for DE is the non-zero Einstein Cosmological Constant $\Lambda_{E}$ manifested as a constant energy density of the vacuum, yet it seemingly defies gravitational effects. In this work, we interpret the non-zero $\Lambda_{E}$ through the lens of scale-invariant cosmology. We revisit the conformal scale factor $\lambda$ and its defining equations within the Scale-Invariant Vacuum (SIV) paradigm. Furthermore, we address the profound problem of the missing mass across galactic and extragalactic scales by deriving an MOND-like relation, $g \sim \sqrt{a_0\,g_N}$, within the SIV context. Remarkably, the values obtained for $\Lambda_{E}$ and the MOND fundamental acceleration, $a_0$, align with observed magnitudes, specifically, $a_0 \approx 10^{-10} \, \mathrm{m} \, \mathrm{s}^{-2}$ and $\Lambda_{E} \approx 1.8 \times 10^{-52} \, \mathrm{m}^{-2}$. Moreover, we propose a novel early dark energy term, $\tilde{T}_{\mu\nu} \sim \kappa H$, within the SIV paradigm, which holds potential relevance for addressing the Hubble tension. Keywords: cosmology; theory; dark energy; dark matter; MOND; Weyl integrable geometry.