Results 91 to 100 of about 11,605 (193)
Can noncommutative effects account for the present speed up of the cosmic expansion?
, 2011 In this paper we investigate to which extent noncommutativity, a intrinsically quantum property, may influence the Friedmann-Robertson-Walker cosmological dynamics at late times/large scales.
Obregon, Octavio, Quiros, Israel
core +1 more source
Complex Riemannian Spacetime and Singularity-Free Black Holes and Cosmology
AxiomsAn approach is presented to address singularities in general relativity using a complex Riemannian spacetime extension. We demonstrate how this method can be applied to both black hole and cosmological singularities, specifically focusing on the ...
John W. Moffat
doaj +1 more source
Deviation of geodesics in FLRW spacetime geometries [PDF]
, 1997 The geodesic deviation equation (`GDE') provides an elegant tool to investigate the timelike, null and spacelike structure of spacetime geometries. Here we employ the GDE to review these structures within the Friedmann--Lema\^{\i}tre--Robertson--Walker (`
Ellis, George F R, van Elst, Henk
core +2 more sources
Analyzing cosmic inhomogeneities through perturbative modifications of FLRW spacetime
European Physical Journal C: Particles and FieldsThis research study investigates the modification of Friedmann–Lemaitre–Robertson–Walker (FLRW) spacetime, emphasizing the effects of universe expansion, dark matter, and cosmological perturbations.
Mutahir Ali, Farhad Ali
doaj +1 more source
Cosmological scaling solutions of minimally coupled scalar fields in three dimensions
, 2000 We examine Friedmann-Robertson-Walker models in three spacetime dimensions. The matter content of the models is composed of a perfect fluid, with a $\gamma$-law equation of state, and a homogeneous scalar field minimally coupled to gravity with a self ...
Barrow J D +8 more
core +1 more source
Physics Letters B, 2017 Motivated by a recent finding of an exact solution of the relativistic Boltzmann equation in a Friedmann–Robertson–Walker spacetime, we implement this metric into the newly developed transport approach Simulating Many Accelerated Strongly-interacting ...
J. Tindall +3 more
doaj +1 more source
McVittie–Plummer Spacetime: Plummer Sphere Immersed in the FLRW Universe
The Astrophysical JournalThe McVittie–Plummer spacetime is a spherically symmetric inhomogeneous cosmological model that represents a spherical star system embedded in a standard Friedmann–Lemaître–Robertson–Walker (FLRW) cosmological model. We study the main physical properties
Javad Tabatabaei +2 more
doaj +1 more source
, 2019 In this paper we investigate the quantum Brownian motion of a massive scalar point particle induced by the FRW spacetime in the presence of a linear topological defect named cosmic string. In addition, we also consider a flat boundary orthogonal to the defect to analyse its effect on the particle's motion.
Mota, Herondy F. Santana +1 more
openaire +2 more sources
Gravitational Entropy and the Second Law of Thermodynamics
Entropy, 2015 The spontaneous violation of Lorentz and diffeomorphism invariance in a phase near the big bang lowers the entropy, allowing for an arrow of time and the second law of thermodynamics. The spontaneous symmetry breaking leads to
John W. Moffat
doaj +1 more source
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 +2 more
openaire +2 more sources