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Polymer models inspired by Loop Quantum Gravity (LQG) have been used to describe non-singular quantum black holes with spherical symmetry, with the classical singularity replaced by a transition from a black hole to a white hole. A recent…

General Relativity and Quantum Cosmology · Physics 2024-02-01 H. A. Borges , I. P. R. Baranov , F. C. Sobrinho , S. Carneiro

The improved dynamics of loop quantum cosmology is extended to include the Bianchi type II model. Because these space-times admit both anisotropies and non-zero spatial curvature, certain technical difficulties arise over and above those…

General Relativity and Quantum Cosmology · Physics 2010-01-07 Abhay Ashtekar , Edward Wilson-Ewing

We investigate the evolution of cosmological anisotropies within the framework of $f\left(G\right)$-gravity. Specifically, we consider a locally rotationally symmetric geometry in four-dimensional spacetime that describes the Bianchi I,…

General Relativity and Quantum Cosmology · Physics 2025-12-25 R. Bogadi , A. Giacomini , M. Govender , C. Hansraj , G. Leon , A. Paliathanasis

A recently proposed version of mimetic gravity incorporates a limiting curvature into general relativity by means of a specific potential depending on the d'Alembertian of the scalar field. In the homogeneous and isotropic setting, the…

General Relativity and Quantum Cosmology · Physics 2019-10-28 Norbert Bodendorfer , Fabio M. Mele , Johannes Münch

We investigate the effects of the underlying quantum geometry in loop quantum cosmology on spacetime curvature invariants and the extendibility of geodesics in the Bianchi-I model for matter with a vanishing anisotropic stress. Using the…

General Relativity and Quantum Cosmology · Physics 2012-07-05 Parampreet Singh

We present an effective theory to describe the quantization of spherically symmetric vacuum in loop quantum gravity. We include anomaly-free holonomy corrections through a canonical transformation of the Hamiltonian of general relativity,…

General Relativity and Quantum Cosmology · Physics 2023-04-18 Asier Alonso-Bardaji , David Brizuela , Raül Vera

Polymer models have been used to describe non-singular quantum black holes, where the classical singularity is replaced by a transition from a black hole to a white hole. In a previous letter, in the context of a uni-parametric model with…

General Relativity and Quantum Cosmology · Physics 2025-04-15 I. P. R. Baranov , H. A. Borges , F. C. Sobrinho , S. Carneiro

In this work, we study self-gravitating objects that obey a polytropic equation of state in hyperbolic symmetry. Specifically, we describe in detail the steps to derive the Lane-Emden equation from the structure equations of the system. To…

General Relativity and Quantum Cosmology · Physics 2025-05-29 M. Carrasco-H , E. Contreras , E. Fuenmayor , P. León

We present a review on basic aspects of quantum cosmology in the presence of cut-off physics. We first analyze how the Wheeler-DeWitt equation in a pure metric approach describes the quantum Universe, showing how the singularity is not…

General Relativity and Quantum Cosmology · Physics 2021-09-20 Gabriele Barca , Eleonora Giovannetti , Giovanni Montani

We model gravitating relativistic 3D spheres composed of an anisotropic fluid in which the radial and transverse components of the pressure correspond to the vacuum energy and a generalized polytropic equation-of-state, respectively. By…

General Relativity and Quantum Cosmology · Physics 2024-05-20 Seyed Naseh Sajadi , Mohsen Khodadi , Orlando Luongo , Hernando Quevedo

We study the quantum mechanics of self-gravitating thin shell collapse by solving the polymerized Wheeler-DeWitt equation. We obtain the energy spectrum and solve the time dependent equation using numerics. In contradistinction to the…

General Relativity and Quantum Cosmology · Physics 2016-12-07 Jonathan Ziprick , Jack Gegenberg , Gabor Kunstatter

In this paper, we continue the analysis of the effective model of quantum Schwarzschild black holes recently proposed by some of the authors in [1,2]. In the resulting spacetime the central singularity is resolved by a black-to-white hole…

General Relativity and Quantum Cosmology · Physics 2022-02-28 Fabio M. Mele , Johannes Münch , Stratos Pateloudis

Inspired by the Lifshitz gravity as a theory with anisotropic scaling behavior, we suggest a new $(n+1)-$dimensional metric in which the time and spatial coordinates scale anisotropically as $(t,r,\theta_{i})\,\to…

General Relativity and Quantum Cosmology · Physics 2022-12-06 S. Mahmoudi , Kh. Jafarzade , S. H. Hendi

To complement recent work on tests of spacetime symmetry in gravity, cubic curvature couplings are studied using an effective field theory description of spacetime-symmetry breaking. The associated mass dimension 8 coefficients for Lorentz…

General Relativity and Quantum Cosmology · Physics 2016-09-28 Quentin G. Bailey

Extending our previous analysis, we study the interior of a Schwarzschild black hole derived from a partial gauge fixing of the full Loop Quantum Gravity Hilbert space, this time including the inverse volume and coherent state subleading…

General Relativity and Quantum Cosmology · Physics 2020-09-30 Emanuele Alesci , Sina Bahrami , Daniele Pranzetti

This paper examines the general formalism and applications of isotropic as well as anisotropic polytropic stars in curvature-matter coupled gravity. For this purpose, we consider static spherical and Schwarzschild spacetimes in the interior…

General Relativity and Quantum Cosmology · Physics 2022-02-16 M. Sharif , Amal Majid , M. Shafaqat

Quantum gravity is effective in domains where both quantum effects and gravity are essential, such as in the vicinity of space-time singularities. This paper will investigate the quantization of a black-hole gravity, particularly the region…

General Relativity and Quantum Cosmology · Physics 2022-09-16 Carla Rodrigues Almeida , Denis Campos Rodrigues

In this paper we systematically study a five-parameters class of spherically symmetric polymer black/white hole solutions, and find that only three independent combinations are physical and uniquely determine the spacetime properties. After…

General Relativity and Quantum Cosmology · Physics 2022-03-16 Wen-Cong Gan , Nilton O. Santos , Fu-Wen Shu , Anzhong Wang

It is believed that soon after the Planck time, Einstein's general relativity theory should be corrected to an effective quadratic theory. Numerical solutions for the anisotropic generalization of the Friedmann "open" model $H^ 3$ for this…

General Relativity and Quantum Cosmology · Physics 2012-04-11 Juliano A. de Deus , Daniel Müller

We numerically investigate the solutions to the effective equations of the Bianchi II model within the "improved" Loop Quantum Cosmology (LQC) dynamics. The matter source is a massless scalar field. We perform a systematic study of the…

General Relativity and Quantum Cosmology · Physics 2012-10-08 Alejandro Corichi , Edison Montoya