Results 31 to 40 of about 51,813 (205)

The Einstein static universe in Loop Quantum Cosmology [PDF]

, 2007
Loop Quantum Cosmology strongly modifies the high-energy dynamics of Friedman-Robertson-Walker models and removes the big-bang singularity. We investigate how LQC corrections affect the stability properties of the Einstein static universe.
Arrowsmith C K, Ashtekar A, Ashtekar A, Barrow J D, Bojowald M, Eddington A S, Eddington A S, Ellis G F R, Ellis G F R, Gergely L A, Guth A H, Guth A H, Harrison E R, Kevin Vandersloot, Luca Parisi, Marco Bruni, Mukherjee S, Rebhan E, Rovelli C, Roy Maartens, Thiemann T   +20 more
core   +2 more sources

Dark Energy Problem, Physics of Early Universe and Some New Approaches in Gravity

Entropy, 2012
The dark energy problem is studied based on the approach associated with the cosmological term in General Relativity that is considered as a dynamic quantity.
Alexander Shalyt-Margolin
doaj   +1 more source

The Vacuum State of Primordial Fluctuations in Hybrid Loop Quantum Cosmology

Universe, 2018
We investigate the role played by the vacuum of the primordial fluctuations in hybrid Loop Quantum Cosmology. We consider scenarios where the inflaton potential is a mass term and the unperturbed quantum geometry is governed by the effective dynamics of ...
Beatriz Elizaga Navascués, Daniel Martín de Blas, Guillermo A. Mena Marugán   +2 more
doaj   +1 more source

Complex Riemannian Spacetime and Singularity-Free Black Holes and Cosmology

Axioms
An 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

Effective f(R) Actions for Modified Loop Quantum Cosmologies via Order Reduction

Universe, 2023
General Relativity is an extremely successful theory, at least for weak gravitational fields; however, it breaks down at very high energies, such as in correspondence to the initial singularity.
Ana Rita Ribeiro, Daniele Vernieri, Francisco S. N. Lobo   +2 more
doaj   +1 more source

Minisuperspace Examples of Quantization Using Canonical Variables of the Ashtekar Type: Structure and Solutions

, 1995
The Ashtekar variables have been use to find a number of exact solutions in quantum gravity and quantum cosmology. We investigate the origin of these solutions in the context of a number of canonical transformations (both complex and real) of the basic ...
A. Ashtekar, A. Lafiti, A. Taub, C. Misner, H. Kodama, H. Kodama, I. E. Segal, J. F. Barbero, J. Fernando Barbero, J. Hartle, K. Kuchař, M. Ryan, Michael P. Ryan, O. Obregon, P. D'Eath, R. Graham, V. Bargmann, V. Belinskii, V. Moncrief   +18 more
core   +1 more source

The 1919 measurement of the deflection of light [PDF]

, 2014
The measurement of the deflection of starlight during a total solar eclipse on May 29, 1919 was the first verification of general relativity by an external team of scientists, brought Einstein and his theory to the attention of the general public, and ...
Will, Clifford M.
core   +3 more sources

Group Field Theory and Its Cosmology in a Matter Reference Frame

Universe, 2018
While the equations of general relativity take the same form in any coordinate system, choosing a suitable set of coordinates is essential in any practical application.
Steffen Gielen
doaj   +1 more source

Tests of standard cosmology in Hořava gravity, Bayesian evidence for a closed universe, and the Hubble tension

European Physical Journal C: Particles and Fields, 2022
We consider some background tests of standard cosmology in the context of Hořava gravity with different scaling dimensions for space and time, which has been proposed as a renormalizable, higher-derivative, Lorentz-violating quantum gravity model without
Nils A. Nilsson, Mu-In Park
doaj   +1 more source

Effective actions for loop quantum cosmology in fourth-order gravity

European Physical Journal C: Particles and Fields, 2021
Loop quantum cosmology (LQC) is a theory which renders the Big Bang initial singularity into a quantum bounce, by means of short-range repulsive quantum effects at the Planck scale.
Marcello Miranda, Daniele Vernieri, Salvatore Capozziello, Francisco S. N. Lobo   +3 more
doaj   +1 more source