Results 101 to 110 of about 6,154 (134)

Friedmann-Robertson-Walker spacetimes from the perspective of geometric algebra

The intention of our paper is to provide a pedagogical application of geometric algebra to a particularly well-investigated system: We formulate the geometric and dynamical properties of Friedmann-Robertson-Walker spacetimes within the language of geometric algebra and re-derive the Friedmann-equations as the central cosmological equations. Through the
Perez, Pablo Banon, Schaefer, Bjoern Malte, DeKieviet, Maarten   +2 more
openaire   +2 more sources

Weighing the curvature invariants

European Physical Journal C: Particles and Fields
We prove several inequalities between the curvature invariants, which impose constraints on curvature singularities. Some of the inequalities hold for a family of spacetimes which include static, Friedmann–Lemaître–Robertson–Walker, and Bianchi type I ...
Jan Dragašević, Ina Moslavac, Ivica Smolić   +2 more
doaj   +1 more source

On the Necessity of Phantom Fields for Solving the Horizon Problem in Scalar Cosmologies

Universe, 2019
We discuss the particle horizon problem in the framework of spatially homogeneous and isotropic scalar cosmologies. To this purpose we consider a Friedmann–Lemaître–Robertson–Walker (FLRW) spacetime with possibly non-zero spatial ...
Davide Fermi, Massimo Gengo, Livio Pizzocchero   +2 more
doaj   +1 more source

Signatures of primordial gravitational waves in matter power spectrum

European Physical Journal C: Particles and Fields, 2019
We simulate the evolution of a dust universe from $$z=1089$$ z=1089 to $$z=0$$ z=0 by numerically integrating the Einstein’s equation for a spatially flat Friedmann–Lemaire–Robertson–Walker (FLRW) background spacetime with scalar perturbations which are ...
Ke Wang
doaj   +1 more source

On the Effects of Non-Metricity in an Averaged Universe

Universe
In the covariant averaging scheme of macroscopic gravity, the process of averaging breaks the metricity of geometry. We reinterpret the back-reaction within macroscopic gravity in terms of the non-metricity of averaged geometry.
Anish Agashe, Sai Madhav Modumudi
doaj   +1 more source

Deformation quantization in FLRW geometries

European Physical Journal C: Particles and Fields
We investigate the application of deformation quantization to the system of a free particle evolving within a universe described by a Friedmann–Lemaître–Robertson–Walker (FLRW) geometry.
Alfonso F. Bobadilla, Jose A. R. Cembranos   +1 more
doaj   +1 more source

Generalized Misner-Sharp energy in f(R,G) gravity

Physics Letters B
In this work, we explore the formulation of the Misner-Sharp energy within the framework of f(R,G) gravity, a modified theory incorporating the Ricci scalar R and the Gauss-Bonnet scalar G.
Amin Rezaei Akbarieh, Navid Safarzadeh Ilkhchi, Yaghoub Heydarzade   +2 more
doaj   +1 more source

Cosmological evolution driven by polytropic fluids in an inhomogeneous spacetime

European Physical Journal C: Particles and Fields
Addressing the late-time accelerated expansion of the universe, known as the “dark energy problem”, remains a central challenge in cosmology. While the cosmological constant is the standard explanation, alternative models such as quintessence, phantom ...
Gilberto Aguilar-Pérez, Miguel Cruz, Mohsen Fathi, Daniel de Jesús García-Castro, J. R. Villanueva   +4 more
doaj   +1 more source

Mechanical cosmology: Simulating scalar fluctuations in expanding universes using synthetic mechanical lattices

Physical Review Research
Inspired by recent advances in observational astrophysics and continued explorations in the field of analog gravity, we discuss the prospect of simulating models of cosmology within the context of synthetic mechanical lattice experiments. We focus on the
Brendan Rhyno, Ivan Velkovsky, Peter Adshead, Bryce Gadway, Smitha Vishveshwara   +4 more
doaj   +1 more source

WITHDRAWN: Local causality in a Friedmann–Robertson–Walker spacetime [PDF]

Annals of Physics, 2016
openaire   +1 more source