2022/01/31 by Ekim Taylan Hanımeli, I. Tutusaus, Isaac Tutusaus +2 · 2 citations
Physics and Astronomy · #Astrophysics #Black Holes and Theoretical Physics #Classical mechanics #Cosmological constant #Cosmology #Cosmology and Gravitation Theories #Dark energy #Equation of state #Galaxies: Formation, Evolution, Phenomena #Geometry #Gravitation #Inflation (cosmology) #Lambda-CDM model #Metric expansion of space #Physics #Quantum mechanics #Spacetime #Tensor (intrinsic definition) #Theoretical physics #Universe #astro-ph.CO #gr-qc
paper · pdf · open access · doi:10.3390/universe8030148
published in Universe 8(3), 148 (Multidisciplinary Digital Publishing Institute) · Prepared for the proceedings of Alternative Gravities and Fundamental Cosmology - ALTECOSMOFUN'21 (https://indico.cern.ch/event/873762/) conference. Matches the version published at Universe Special Issue: Alternative Gravities and Fundamental Cosmology
openalex publication_date 2022/02/25 · arxiv created 2022/02/28 · arxiv updated 2022/03/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The accelerated expansion of the universe implies the existence of an energy contribution known as dark energy. Associated with the cosmological constant in the standard model of cosmology, the nature of this dark energy is still unknown. We will discuss an alternative gravity model in which this dark energy contribution emerges naturally, as a result of allowing for a time-dependence on the gravitational constant, G, in Einstein's field equations. With this modification, Bianchi's identities require an additional tensor field to be introduced so that the usual conservation equation for matter and radiation is satisfied. The equation of state of this tensor field is obtained using additional constraints, coming from the assumption that this tensor field represents the space-time response to the variation of G. We will also present the predictions of this model for the late-universe data, and show that the energy contribution of this new tensor is able to explain the accelerated expansion of the universe without the addition of a cosmological constant. Unlike many other alternative gravities with varying gravitational strength, the predicted G evolution is also consistent with local observations and therefore this model does not require screening. We will finish by discussing possible other implications this approach might have for cosmology and some future prospects.