2020/12/31 by Alfio Bonanno, A. Bonanno, Georgios Kofinas +1 · 19 citations
Mathematics · Physics and Astronomy · #Black Holes and Theoretical Physics #Classical mechanics #Cosmological constant #Cosmology #Cosmology and Gravitation Theories #Curvature #Dark energy #Einstein #Einstein field equations #Field equation #Formalism (music) #Friedmann–Lemaître–Robertson–Walker metric #Geometry #Gravitational field #Lambda #Mathematical physics #Mathematics #Metric expansion of space #Physics #Quantum mechanics #Solar and Space Plasma Dynamics #Theoretical physics #Universe #astro-ph.CO #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.103.104025
published in Physical review. D/Physical review. D. 103(10) (American Physical Society) · 21 pages, 12 figures, to appear in PRD
arxiv created 2021/04/07 · openalex publication_date 2021/05/14 · arxiv updated 2021/05/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
A new set of field equations for a space-time dependent Newton's constant G(x) and cosmological constant \mathrm\ensuremathΛ(x) in the presence of matter is presented. We prove that it represents the most general mathematically consistent, physically plausible, set of evolution equations assuming at most second derivatives in the dynamical variables. In the new Einstein's equations, only \mathrm\ensuremathΛ-kinetic terms arise, while in the modified conservation equation, derivative terms of G also appear. As an application, this formalism is applied in the context of the asymptotic safety scenario to the early Universe, assuming a perfect fluid with a radiation equation of state. Cosmological solutions are obtained for all types of spatial curvature, displaying a variety of interesting cosmic evolutions. As an indication of such behaviors, bouncing solutions, recollapsing solutions, or nonsingular expanding solutions with a transient acceleration era are discussed in detail.