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A fully consistent linear perturbation theory for cosmology is derived in the presence of quantum corrections as they are suggested by properties of inverse volume operators in loop quantum gravity. The underlying constraints present a…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald , Golam Mortuza Hossain , Mikhail Kagan , S. Shankaranarayanan

Gravity theory is the basis of modern cosmological models. Thirring-Feynman's tensor field approach to gravitation is an alternative to General Relativity (GR). Though Field Gravity (FG) approach is still developing subject, it opens new…

General Relativity and Quantum Cosmology · Physics 2016-08-31 Yurij Baryshev

We study the growth of subhorizon perturbations in brane-induced gravity using perturbation theory. We solve for the linear evolution of perturbations taking advantage of the symmetry under gauge transformations along the extra-dimension to…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-10 Roman Scoccimarro

We apply the full theory of Loop Quantum Gravity (LQG) to cosmology and present a top-down derivation of gauge-invariant cosmological perturbation theory from quantum gravity. The derivation employs the reduced phase space formulation of…

General Relativity and Quantum Cosmology · Physics 2021-01-20 Muxin Han , Haida Li , Hongguang Liu

Gravitational decoherence (GD) refers to the effects of gravity in actuating the classical appearance of a quantum system. Because the underlying processes involve issues in general relativity (GR), quantum field theory (QFT) and quantum…

General Relativity and Quantum Cosmology · Physics 2024-06-19 Charis Anastopoulos , Bei-Lok Hu

A finite quantum gravity theory is used to resolve the cosmological constant problem. A fundamental quantum gravity scale, \Lambda_G \leq 10^{-3} eV, is introduced above which the quantum corrections to the vacuum energy density coupled to…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. W. Moffat

Assuming that Quantum Einstein Gravity (QEG) is the correct theory of gravity on all length scales we use analytical results from nonperturbative renormalization group (RG) equations as well as experimental input in order to characterize…

High Energy Physics - Theory · Physics 2009-09-24 M. Reuter , H. Weyer

We apply recent advances in quantum gravity to the problem of turbulence. Adopting the AdS/CFT approach we propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov…

General Relativity and Quantum Cosmology · Physics 2011-01-17 Vishnu Jejjala , Djordje Minic , Y. Jack Ng , Chia-Hsiung Tze

We give a review of recent work aimed at understanding the dynamics of gravitational collapse in quantum gravity. Its goal is to provide a non-perturbative computational framework for understanding the emergence of the semi-classical…

General Relativity and Quantum Cosmology · Physics 2008-01-09 Viqar Husain

The early universe provides an opportunity for quantum gravity to connect to observation by explaining the large-scale structure of the Universe. In the group field theory (GFT) approach, a macroscopic universe is described as a GFT…

General Relativity and Quantum Cosmology · Physics 2018-12-05 Steffen Gielen , Daniele Oriti

We recall a classical theory of torsion gravity with an asymmetric metric, sourced by a Nambu-Goto + Kalb-Ramond string . We explain why this is a significant gravitational theory, and in what sense classical general relativity is an…

General Relativity and Quantum Cosmology · Physics 2019-07-01 Tejinder P. Singh

We study the evolution of scalar cosmological perturbations in the (1+3)- covariant gauge-invariant formalism for generic $f(R)$ theories of gravity. Extending previous works, we give a complete set of equations describing the evolution of…

General Relativity and Quantum Cosmology · Physics 2012-06-08 Amare Abebe , Mohamed Abdelwahab , Alvaro de la Cruz-Dombriz , Peter K. S. Dunsby

Gravitation is described in the context of a dilatonic theory that is conformally related to general relativity. All dimensionless ratios of fundamental dimensional quantities, e.g. particle masses and the Planck mass, as well as the…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-21 Meir Shimon

Although general relativity is a predictively successful theory, it treats matter as classical rather than as quantum. For this reason, it will have to be replaced by a more fundamental quantum theory of gravity. Attempts to formulate a…

History and Philosophy of Physics · Physics 2019-02-07 Christian Wuthrich

The Hamiltonian formulation of general relativity (GR) is considered in finite space-time and a specific frame of reference given by the diffeo-invariant components of the Fock simplex in terms of the Dirac -- ADM variables. The evolution…

Astrophysics · Physics 2009-11-13 B. M. Barbashov , V. N. Pervushin , A. F. Zakharov , V. A. Zinchuk

We present a new model of quantum gravity as a theory of random geometries given explicitly in terms of a multitrace matrix model. This is a generalization of the usual discretized random surfaces of 2D quantum gravity which works away from…

High Energy Physics - Theory · Physics 2017-11-22 Badis Ydri , Cherine Soudani , Ahlam Rouag

Loop quantum cosmology is a symmetry reduced quantization of cosmological spacetimes based on loop quantum gravity. While it has been successful in resolution of various cosmological singularities and connecting Planck scale physics to…

General Relativity and Quantum Cosmology · Physics 2019-12-25 Klaus Liegener , Parampreet Singh

Getting signatures of quantum gravity is one of the topical lines of research in modern theoretical physics and cosmology. This short review faces this challenge under a novel perspective. Instead of separating quantum-gravity effects of a…

General Relativity and Quantum Cosmology · Physics 2017-10-24 Gianluca Calcagni

A central open problem in quantum gravity is to understand how continuum spacetime emerges from quantum-geometric degrees of freedom in a background-independent setting. A many-body perspective suggests that spacetime emerges as a…

General Relativity and Quantum Cosmology · Physics 2026-05-20 Andrea Calcinari , Adrià Delhom , Daniele Oriti

The continual production of long wavelength gravitons during primordial inflation endows graviton loop corrections with secular growth factors. During a prolonged period of inflation these factors eventually overwhelm the small…

General Relativity and Quantum Cosmology · Physics 2024-09-19 S. P. Miao , N. C. Tsamis , R. P. Woodard