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In this paper a quantum mechanical phase space picture is constructed for coarse-grained free quantum fields in an inflationary Universe. The appropriate stochastic quantum Liouville equation is derived. Explicit solutions for the phase…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Salman Habib

Two-dimensional quantum gravity is identified as a second-class system which we convert into a first-class system via the Batalin-Fradkin (BF) procedure. Using the extended phase space method, we then formulate the theory in most general…

High Energy Physics - Theory · Physics 2016-09-06 T. Fujiwara , Y. Igarashi , J. Kubo , T. Tabei

In recent years it has emerged that the high energy behavior of gravity could be governed by an ultraviolet non-Gaussian fixed point of the (dimensionless) Newton's constant, whose behavior at high energy is thus {\it antiscreened}. This…

High Energy Physics - Theory · Physics 2011-08-17 Alfio Bonanno

Poincare recurrence theorem states that any finite system will come arbitrary close to its initial state after some very long but finite time. At the statistical level, this by itself does not represent a paradox, but apparently violates…

General Relativity and Quantum Cosmology · Physics 2017-01-26 Ruifeng Dong , Dejan Stojkovic

On one popular view, the general covariance of gravity implies that change is relational in a strong sense, such that all it is for a physical degree of freedom to change is for it to vary with regard to a second physical degree of freedom.…

General Relativity and Quantum Cosmology · Physics 2018-01-18 Sean Gryb , Karim Thebault

Crystals, as quantum objects typically much larger than their lattice spacing, are a counterexample to a frequent prejudice that quantum effects should not be pronounced at macroscopic distances. We propose that the Einstein theory of…

High Energy Physics - Theory · Physics 2015-11-06 H. Nikolic

We show how to formulate a lattice gauge theory whose naive continuum limit corresponds to two-dimensional (Euclidean) quantum gravity including a positive cosmological constant. More precisely the resultant continuum theory corresponds to…

High Energy Physics - Lattice · Physics 2020-09-23 Muhammad Asaduzzaman , Simon Catterall , Judah Unmuth-Yockey

We propose a criterion for the validity of semiclassical gravity (SCG) which is based on the stability of the solutions of SCG with respect to quantum metric fluctuations. We pay special attention to the two-point quantum correlation…

General Relativity and Quantum Cosmology · Physics 2009-11-10 B. L. Hu , Albert Roura , Enric Verdaguer

We explore the generalized covariant entropy bound in the theory where Einstein gravity is perturbed by quadratic curvature terms, which can be viewed as the first-order quantum correction to Einstein gravity. By replacing the…

General Relativity and Quantum Cosmology · Physics 2023-11-10 Hu Zhu , Jie Jiang

We here conjecture that two much-studied aspects of quantum gravity, dimensional flow and spacetime fuzziness, might be deeply connected. We illustrate the mechanism, providing first evidence in support of our conjecture, by working within…

High Energy Physics - Theory · Physics 2017-11-15 Giovanni Amelino-Camelia , Gianluca Calcagni , Michele Ronco

We describe a scheme for the exploration of quantum gravity phenomenology focussing on effects that could be thought as arising from a fundamental granularity of space-time. In contrast with the simplest assumptions, such granularity is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Yuri Bonder , Daniel Sudarsky

It is shown that a coherent understanding of all quantized phenomena, including those governed by unitary evolution equations as well as those related to irreversible quantum measurements, can be achieved in a scenario of successive…

Quantum Physics · Physics 2007-12-31 Xiaolei Zhang

Gravity whose nature is fundamental to the understanding of solar system, galaxies and the structure and evolution of the Universe, is theorized by the assumption of curved spacetime, according to Einstein`s general theory of relativity…

Astrophysics · Physics 2007-10-22 Jin He

A nonpertubative approach to quantum gravity using precanonical field quantization originating from the covariant De Donder-Weyl Hamiltonian formulation which treats space and time variables on equal footing is presented. A generally…

General Relativity and Quantum Cosmology · Physics 2014-11-17 I. V. Kanatchikov

In this short note we review a recently found formulation of two-dimensional causal quantum gravity defined through Causal Dynamical Triangulations and stochastic quantization. This procedure enables one to extract the nonperturbative…

High Energy Physics - Theory · Physics 2014-11-20 J. Ambjorn , R. Loll , W. Westra , S. Zohren

The properties of the quantum universe on extremely small spacetime scales are studied in the semi-classical approach to the well-defined quantum model. It is shown that near the initial cosmological singularity point quantum gravity…

General Relativity and Quantum Cosmology · Physics 2010-04-30 V. E. Kuzmichev , V. V. Kuzmichev

Doubly special relativity has been studied for the last twenty years as a way to go beyond the special relativistic kinematics, trying to capture residual effects of a quantum gravity theory. In particular, in doubly special relativity the…

General Relativity and Quantum Cosmology · Physics 2022-07-19 J. J. Relancio

We construct a model of quantum gravity in which dimension, topology and geometry of spacetime are dynamical. The microscopic degree of freedom is a real rectangular matrix whose rows label internal flavours, and columns label spatial…

High Energy Physics - Theory · Physics 2020-12-14 Sung-Sik Lee

Two-spinor formalism for Einstein Lagrangian is developed. The gravitational field is regarded as a composite object derived from soldering forms. Our formalism is geometrically and globally well-defined and may be used in virtually any…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Marco Godina , Paolo Matteucci , Lorenzo Fatibene , Mauro Francaviglia

A classical two dimensional theory of gravity which has a number of interesting features (including a Newtonian limit, black holes and gravitational collapse) is quantized using conformal field theoretic techniques. The critical dimension…

High Energy Physics - Theory · Physics 2009-10-22 R. B. Mann