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The results of canonical quantum gravity concerning geometric operators and black hole entropy are beset by an ambiguity labelled by the Immirzi parameter. We use a result from classical gravity concerning the quasinormal mode spectrum of a…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Olaf Dreyer

The standard LambdaCDM model of cosmology is usually understood to arise from demanding that the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric satisfy the General Relativity dynamics for spacetime metrics. The FLRW data-based dominant…

General Physics · Physics 2009-07-13 Reginald T Cahill

In our recently proposed quantum theory of gravity, the universe is made of `atoms' of space-time-matter (STM). Planck scale foam is composed of STM atoms with Planck length as their associated Compton wave-length. The quantum dispersion…

General Relativity and Quantum Cosmology · Physics 2020-08-03 Tejinder P. Singh

One parameter quantization ambiguity is existed in Loop quantum gravity which is called the Immirzi parameter. In this paper, we fix this free paremater by considering the quasinormal mode spectrum of black holes in four and higher…

General Relativity and Quantum Cosmology · Physics 2016-10-13 Xiangdong Zhang

In this essay it is proved that, in a self-consistent semiclassical theory of gravity, the asymptotically measured orbital periods of test particles around central compact objects are fundamentally bounded from below by the compact…

General Relativity and Quantum Cosmology · Physics 2025-04-16 Shahar Hod

There have been a number of claims in the literature about gravity shielding effects of superconductors and more recently on the weight reduction of superconductors passing through their critical temperature. We report several experiments…

General Relativity and Quantum Cosmology · Physics 2009-11-10 M. Tajmar , K. Hense , K. Marhold , C. J. de Matos

Loop Quantum Gravity (LQG) is a theory that proposes a way to model the behavior of the spacetime in situations where its atomic characteristic arises. Among these situations, the spacetime behavior near the Big Bang or black hole's…

General Relativity and Quantum Cosmology · Physics 2019-03-08 M. B. Cruz , C. A. S. Silva , F. A. Brito

Belenchia et al. [Phys. Rev. D 98, 126009 (2018)] have analyzed a gedankenexperiment where two observers, Alice and Bob, attempt to communicate via superluminal signals using a superposition of massive particles dressed by Newtonian fields…

General Relativity and Quantum Cosmology · Physics 2026-01-30 Felipe Sobrero , Luca Abrahão , Thiago Guerreiro

We explore a possible connection between two aspects of Loop Quantum Gravity which have been extensively studied in the recent literature: the black-hole area-entropy law and the energy-momentum dispersion relation. We observe that the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Giovanni Amelino-Camelia , Michele Arzano , Andrea Procaccini

Quantum gravity effects of zeroth order in the Planck constant are investigated in the framework of the low-energy effective theory. A special emphasis is placed on establishing the correspondence between classical and quantum theories, for…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Kirill A. Kazakov

Source-free equations of nonlinear electrodynamics minimally coupled to gravity admit regular axially symmetric asymptotically Kerr-Newman solutions which describe charged rotating black holes and electromagnetic spinning solitons (lumps).…

General Relativity and Quantum Cosmology · Physics 2015-10-06 Irina Dymnikova

Although well motivated from theoretical arguments, the cosmological constant \emph{barrier}, i.e., the imposition that the equation-of-state parameter of dark energy ($\omega_x \equiv p_x/\rho_x$) is $\geq -1$, seems to introduce bias in…

Astrophysics · Physics 2009-11-10 J. S. Alcaniz

We discuss the semiclassical limit of Quantum Reduced Loop Gravity, a recently proposed model to address the quantum dynamics of the early Universe. We apply the techniques developed in full Loop Quantum Gravity to define the semiclassical…

General Relativity and Quantum Cosmology · Physics 2015-06-18 Emanuele Alesci , Francesco Cianfrani

We present a phenomenological study of rotating, charged black holes in Einstein gravity coupled to a traceless (conformal) matter sector formed by ModMax nonlinear electrodynamics and a Kalb-Ramond two-form that spontaneously breaks local…

General Relativity and Quantum Cosmology · Physics 2025-09-23 Yassine Sekhmani , Kuantay Boshkayev , Mustapha Azreg-Aïnou , Sunil K. Maurya , Mohamed Altanji , Ainur Urazalina

Lorentz Invariance Violation (LIV) arises in various quantum-gravity theories. As the typical energy for quantum gravity is the Planck mass, $M_{pl}$, LIV will, most likely, be manifested at very high energies that are not accessible on…

High Energy Physics - Phenomenology · Physics 2008-11-26 Uri Jacob , Tsvi Piran

We showed in a previous paper that a wide class of nonmetric theories of gravity encompassed by the $\chi g$ formalism predict that the speed of light rays depends on the their polarization direction relative to directions singled out by…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Thierry Kauffmann

When gauge field theory coherent states for loop quantum gravity (LQG) were introduced, an optimized semiclassical proper length emerged, corresponding to the edge length $\epsilon$ of a graph embedded in a given classical geometry. Here…

General Relativity and Quantum Cosmology · Physics 2014-02-20 Paul G. N. de Vegvar

Based upon the holographic principle, Jacobson demonstrated that the spacetime can be viewed as a gas of atoms with a related entropy given by the Bekenstein-Hawking formula. Following this argument, Friedmann equations can be derived by…

General Relativity and Quantum Cosmology · Physics 2015-10-13 C. A. S. Silva

In the loop approach to the quantisation of gravity, one uses a Hilbert space which is too singular for some operators to be realised as derivatives. This is usually addressed by instead using finite difference operators at the Planck…

General Relativity and Quantum Cosmology · Physics 2009-12-17 Robert C. Helling

Near a two-dimensional Ising-type nematic quantum critical point, the quantum fluctuations of the nematic order parameter are coupled to the electrons, leading to non-Fermi liquid behavior and unconventional superconductivity. The interplay…

Superconductivity · Physics 2025-12-24 Jie Huang , Zhao-Kun Yang , Jing-Rong Wang , Guo-Zhu Liu