Topic
Friedmann–Lemaître–Robertson–Walker metric
About: Friedmann–Lemaître–Robertson–Walker metric is a research topic. Over the lifetime, 4113 publications have been published within this topic receiving 87752 citations. The topic is also known as: FLRW metric.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this article, the authors consider inhomogeneous viscous fluids in flat Friedmann-Robertson-Walker universe and investigate the possibility to reproduce the current cosmic acceleration providing a different future evolution with respect to the Cosmological Constant case.
Abstract: We consider inhomogeneous viscous fluids in flat Friedmann-Robertson-Walker universe. We analyze different kinds of such fluids and investigate the possibility to reproduce the current cosmic acceleration providing a different future evolution with respect to the Cosmological Constant case. In particular, we study the presence of finite-future time singularities. We also discuss a general class of “integrable” viscous fluid models whose bulk viscosities obey to a common differential equation.
37 citations
••
TL;DR: In this paper, the Friedmann-Robertson-Walker (FRW) universe and Bianchi I, II universes are investigated in the framework of the generalized uncertainty principle (GUP) with a linear and a quadratic term in Planck length and momentum, which predicts the minimum measurable length as well as maximum measurable momentum.
Abstract: The Friedmann–Robertson–Walker (FRW) universe and Bianchi I, II universes are investigated in the framework of the generalized uncertainty principle (GUP) with a linear and a quadratic term in Planck length and momentum, which predicts the minimum measurable length as well as maximum measurable momentum. We obtain a dynamic cosmological bounce for the FRW universe. With the Bianchi universe, we found that the universe may still be isotropic by implementing GUP. Moreover, the wall velocity appears to be stationary with respect to the universe velocity, which means that when the momentum of the universe evolves into a maximum measurable energy, the bounce is enhanced against the wall, which means that no maximum limit angle is manifested anymore.
37 citations
••
TL;DR: In this article, the Brans-Dicke scalar Fleld equations are modifled with the incorporation of a creation pressure and bulk viscous stress, and the behaviour of the particle number density and bulk viscosity is discussed with the evolution of the scalar fleld.
Abstract: The efiect of bulk viscosity on the evolution of the spatially ∞at Friedmann{Lemaitre{ Robertson{Walker (FLRW) models in the context of open thermodynamical systems, which allow for particle creation, is analysed within the framework of Brans{Dicke (BD) theory. The BD fleld equations are modifled with the incorporation of a creation pressure and bulk viscous stress. A class of physically plausible models has been taken into consideration. The behaviour of the particle number density and bulk viscosity is discussed with the evolution of the Brans{Dicke scalar fleld.
37 citations
••
TL;DR: In this article, the authors study linear scalar perturbations around a flat FLRW background in mimetic Horndeski gravity and obtain the equation of motion for the comoving curvature perturbation.
Abstract: We study linear scalar perturbations around a flat FLRW background in mimetic Horndeski gravity. In the absence of matter, we show that the Newtonian potential satisfies a second-order differential equation with no spatial derivatives. This implies that the sound speed for scalar perturbations is exactly zero on this background. We also show that in mimetic $G^3$ theories the sound speed is equally zero. We obtain the equation of motion for the comoving curvature perturbation (first order differential equation) and solve it to find that the comoving curvature perturbation is constant on all scales in mimetic Horndeski gravity. We find solutions for the Newtonian potential evolution equation in two simple models. Finally we show that the sound speed is zero on all backgrounds and therefore the system does not have any wave-like scalar degrees of freedom.
37 citations
••
TL;DR: In this article, the authors consider the problem of describing the asymptotic behaviour of FRW universes near their spacetime singularities in general relativity and find that the Bel-Robinson energy of these universes in conjunction with the Hubble expansion rate and the scale factor proves to be an appropriate measure leading to a complete classification of the possible singularities.
37 citations