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We present a generally covariant approach to quantum mechanics in which generalized positions, momenta and time variables are treated as coordinates on a fundamental "phase-spacetime." We show that this covariant starting point makes…

High Energy Physics - Theory · Physics 2018-05-31 Gabriel Herczeg , Andrew Waldron

In loop quantum cosmology, non-perturbative quantum gravity effects lead to the resolution of the big bang singularity by a quantum bounce without introducing any new degrees of freedom. Though fundamentally discrete, the theory admits a…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Gonzalo J. Olmo , Parampreet Singh

We generalize the Hamiltonian picture of General Relativity coupled to classical matter, known as geometrodynamics, to the case where such matter is described by a Quantum Field Theory in Curved Spacetime, but gravity is still described by…

General Relativity and Quantum Cosmology · Physics 2024-03-20 J. L. Alonso , C. Bouthelier-Madre , J. Clemente-Gallardo , D. Martínez-Crespo

This paper serves as a preparation of work that focuses on extracting cosmological sectors from Loop Quantum Gravity. We start with studying the extraction of subsystems from classical systems. A classical Hamiltonian system can be reduced…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Tim Koslowski

Dynamical black-hole scenarios have been developed in loop quantum gravity in various ways, combining results from mini and midisuperspace models. In the past, the underlying geometry of space-time has often been expressed in terms of line…

General Relativity and Quantum Cosmology · Physics 2020-09-30 Martin Bojowald

It is well known that in a generally covariant gravitational theory the choice of spacetime scalars as coordinates yields phase-space observables (or "invariants"). However their relation to the symmetry group of diffeomorphism…

General Relativity and Quantum Cosmology · Physics 2009-11-19 J. M. Pons , D. C. Salisbury , K. A. Sundermeyer

The canonical ``loop'' formulation of quantum gravity is a mathematically well defined, background independent, non perturbative standard quantization of Einstein's theory of General Relativity. Some among the most meaningful results of the…

General Relativity and Quantum Cosmology · Physics 2012-06-12 R. De Pietri

A covariant spin-foam formulation of quantum gravity has been recently developed, characterized by a kinematics which appears to match well the one of canonical loop quantum gravity. In particular, the geometrical observable giving the area…

General Relativity and Quantum Cosmology · Physics 2014-11-20 You Ding , Carlo Rovelli

We present an overall picture of the advances in the description of black hole physics from the perspective of loop quantum gravity. After an introduction that discusses the main conceptual issues we present some details about the classical…

General Relativity and Quantum Cosmology · Physics 2015-01-14 J. Fernando Barbero G. , Alejandro Perez

One of the celebrated results of Loop Quantum Gravity (LQG) is the discreteness of the spectrum of geometrical operators such as length, area and volume operators. This is an indication that Planck scale geometry in LQG is discontinuous…

General Relativity and Quantum Cosmology · Physics 2009-02-10 Bianca Dittrich , Thomas Thiemann

The unification of general relativity and quantum theory is one of the fascinating problems of modern physics. One leading solution is Loop Quantum Gravity (LQG). Simulating LQG may be important for providing predictions which can then be…

A general nonperturvative loop quantization procedure for metric modified gravity is reviewed. As an example, this procedure is applied to scalar-tensor theories of gravity. The quantum kinematical framework of these theories is rigorously…

General Relativity and Quantum Cosmology · Physics 2013-04-09 Xiangdong Zhang , Yongge Ma

Emergent modified gravity presents a new class of gravitational theories in which the structure of space-time with Riemannian geometry of a certain signature is not presupposed. Relying on crucial features of a canonical formulation, the…

General Relativity and Quantum Cosmology · Physics 2024-04-09 Martin Bojowald , Erick I. Duque , Dennis Hartmann

After a brief introduction, basic ideas of the quantum Riemannian geometry underlying loop quantum gravity are summarized. To illustrate physical ramifications of quantum geometry, the framework is then applied to homogeneous isotropic…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Abhay Ashtekar

This article will summarize selected aspects of the semiclassical theory of gravity, which involves a classical gravitational field coupled to quantum matter fields. Among the issues which will be discussed are the role of quantum effects…

General Relativity and Quantum Cosmology · Physics 2016-11-23 L. H. Ford

Some of the most outstanding questions in the field of gravitation and geometry remain unsolved as a result of our limited understanding of the global structure of the spacetime geometry and the role played by global spacetime…

General Relativity and Quantum Cosmology · Physics 2008-09-23 M. Iftime

A paradigm describing black hole evaporation in non-perturbative quantum gravity is developed by combining two sets of detailed results: i) resolution of the Schwarzschild singularity using quantum geometry methods; and ii) time-evolution…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Abhay Ashtekar , Martin Bojowald

We study the coupling of massive fermions to the quantum mechanical dynamics of spacetime emerging from the spinfoam approach in three dimensions. We first recall the classical theory before constructing a spinfoam model of quantum gravity…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Winston Fairbairn

A spin (dependent) system treatment of gravity is adopted akin to the Sen-Ashtekar treatment. Time is reinserted into the space ``fluid'' at the quantum Level. This time - the Lorentzian one- is shown to be a vorticity of a ``fluid…

General Physics · Physics 2011-03-07 Koustubh Kabe

The algebraic formulation of the quantum group covariant noncommutative geometry in the framework of the $R$-matrix approach to the theory of quantum groups is given. We consider structure groups taking values in the quantum groups and…

High Energy Physics - Theory · Physics 2011-04-15 A. P. Isaev