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We study the operator that corresponds to the measurement of volume, in non-perturbative quantum gravity, and we compute its spectrum. The operator is constructed in the loop representation, via a regularization procedure; it is finite,…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Carlo Rovelli , Lee Smolin

In this brief note (written as a lengthy letter), we describe the construction of a representation for the Weyl-algebra underlying Loop Quantum Geometry constructed from a diffeomorphism variant state, which corresponds to a ''condensate''…

General Relativity and Quantum Cosmology · Physics 2007-09-24 Tim A. Koslowski

The problem of how space-time responds to gravitating quantum matter in full quantum gravity has been one of the main questions that any program of quantization of gravity should address. Here we analyze this issue by considering the…

General Relativity and Quantum Cosmology · Physics 2016-09-07 Miguel Campiglia , Rodolfo Gambini , Javier Olmedo , Jorge Pullin

We propose an unified approach to loop quantum gravity and Fedosov quantization of gravity following the geometry of double spacetime fibrations and their quantum deformations. There are considered pseudo-Riemannian manifolds enabled with…

General Relativity and Quantum Cosmology · Physics 2009-11-21 Sergiu I. Vacaru

We summarize our recently proposed approach to quantum field theory on noncommutative curved spacetimes. We make use of the Drinfel'd twist deformed differential geometry of Julius Wess and his group in order to define an action functional…

High Energy Physics - Theory · Physics 2011-03-24 Alexander Schenkel

We study gravity coupled to a scalar field in spherical symmetry using loop quantum gravity techniques. Since this model has local degrees of freedom, one has to face ``the problem of dynamics'', that is, diffeomorphism and Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2009-11-19 Rodolfo Gambini , Jorge Pullin , Saeed Rastgoo

It is shown how to construct *-homomorphic quantum stochastic Feller cocycles for certain unbounded generators, and so obtain dilations of strongly continuous quantum dynamical semigroups on C* algebras; this generalises the construction of…

Functional Analysis · Mathematics 2013-05-06 Alexander C. R. Belton , Stephen J. Wills

We use the method of embedding a subsystem (i.e. its observable algebra) into a larger quantum system to extract a cosmological sector from full Loop Quantum Gravity. The application of this method provides a setting for a systematic study…

General Relativity and Quantum Cosmology · Physics 2007-11-08 Tim A. Koslowski

We are concerned with the issue of quantization of a scalar field in a diffeomorphism invariant manner. We apply the method used in Loop Quantum Gravity. It relies on the specific choice of scalar field variables referred to as the polymer…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Wojciech Kaminski , Jerzy Lewandowski , Marcin Bobienski

An important goal is to understand better the relation between full loop quantum gravity (LQG) and the simplified, reduced theory known as loop quantum cosmology (LQC), {\em directly at the quantum level}. Such a firmer understanding would…

General Relativity and Quantum Cosmology · Physics 2015-06-12 Jonathan Engle

The geometro-stochastic method of quantization provides a framework for quantum general relativity, in which the principal frame bundles of local Lorentz frames that underlie the fibre-theoretical approach to classical general relativity…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Eduard Prugovecki

Many non-relativistic Quantum Field Theories with conserved particle number share a common set of symmetries: time dependent spatial diffeomorphisms acting on the background metric and U(1) invariance acting on the background fields which…

High Energy Physics - Theory · Physics 2015-06-12 Stefan Janiszewski , Andreas Karch

We explore the relation between noncommutative geometry, in the spectral triple formulation, and quantum mechanics. To this aim, we consider a dynamical theory of a noncommutative geometry defined by a spectral triple, and study its…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Carlo Rovelli

The loop quantization of Brans-Dicke theory (with coupling parameter $\omega\neq-3/2$) is studied. In the geometry-dynamical formalism, the canonical structure and constraint algebra of this theory are similar to those of general relativity…

General Relativity and Quantum Cosmology · Physics 2012-05-18 Xiangdong Zhang , Yongge Ma

Recently, a generally covariant reformulation of 2 dimensional flat spacetime free scalar field theory known as Parameterised Field Theory was quantized using Loop Quantum Gravity (LQG) type `polymer' representations. Physical states were…

General Relativity and Quantum Cosmology · Physics 2015-01-30 Alok Laddha , Madhavan Varadarajan

Using the Chern-Simon formulation of (2+1) gravity, we derive, for the general asymptotic metrics given by the Fefferman-Graham-Lee theorems, the emergence of the Liouville mode associated to the boundary degrees of freedom of (2+1)…

High Energy Physics - Theory · Physics 2009-10-31 M. Rooman , Ph. Spindel

We present a new quantization scheme for $2D$ gravity coupled to an $SU(2)$ principal chiral field and a dilaton; this model represents a slightly simplified version of stationary axisymmetric quantum gravity. The analysis makes use of the…

High Energy Physics - Theory · Physics 2009-10-28 D. Korotkin , H. Nicolai

In loop quantum gravity in the connection representation, the quantum configuration space $\bar{\mathcal{A}/\mathcal{G}}$, which is a compact space, is much larger than the classical configuration space $\mathcal{A}/% \mathcal{G}$ of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Andreas Doering , Hans F. de Groote

A careful study of the induced transformations on spatial quantities due to 4-dimensional spacetime diffeomorphisms in the canonical formulation of general relativity is undertaken. Use of a general formalism, which indicates the role of…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Frank Antonsen , Fotini Markopoulou

The Ahtekar-Isham C*-algebra known from Loop Quantum Gravity is the algebra of continuous functions on the space of (generalized) connections with a compact structure Lie group. The algebra can be constructed by some inductive techniques…

Mathematical Physics · Physics 2010-11-02 Jerzy Lewandowski , Andrzej Okolow