scholarly journals Cosmological constraints on a classical limit of quantum gravity

2005 ◽  
Vol 72 (4) ◽  
Author(s):  
Damien A. Easson ◽  
Frederic P. Schuller ◽  
Mark Trodden ◽  
Mattias N. R. Wohlfarth
Keyword(s):  
Quantum Gravity ◽  
Classical Limit ◽  
Cosmological Constraints

scholarly journals Classical limit of quantum gravity in an accelerating universe

2005 ◽  
Vol 612 (3-4) ◽  
pp. 93-99 ◽  
Author(s):  
Frederic P. Schuller ◽  
Mattias N.R. Wohlfarth
Keyword(s):  
Quantum Gravity ◽  
Classical Limit ◽  
Accelerating Universe

ON THE GEOMETRIZATION OF BOHMIAN MECHANICS: A NEW APPROACH TO QUANTUM GRAVITY

1998 ◽  
Vol 13 (04) ◽  
pp. 677-693 ◽  
Author(s):  
FATIMAH SHOJAI ◽  
MEHDI GOLSHANI
Keyword(s):  
Quantum Theory ◽  
Quantum Gravity ◽  
Classical Limit ◽  
Bohmian Mechanics ◽  
Present Theory ◽  
Space Time ◽  
New Approach ◽  
Theory Of Motion ◽  
Quantum Theory Of Motion ◽  
De Broglie Bohm

In this paper, a new approach to quantum gravity is presented in which the de-Broglie–Bohm quantum theory of motion is geometrized. This way of considering quantum gravity leads automatically to the fact that the quantum effects are contained in the conformal degree of freedom of the space–time metric. The present theory is then applied to the maximally symmetric space–time of cosmology, and it is observed that it is possible to avoid the initial singularity, while at large times the correct classical limit emerges.

scholarly journals Cosmological constraints on GUP from modified Friedmann equations

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Serena Giardino ◽  
Vincenzo Salzano
Keyword(s):  
Quantum Gravity ◽  
Observational Data ◽  
Generalized Uncertainty Principle ◽  
Linear Formulation ◽  
Minimum Length ◽  
Cosmological Constraints ◽  
Friedmann Equations ◽  
Quantum Gravity Phenomenology ◽  
Cosmological Data

AbstractThe Generalized Uncertainty Principle (GUP) has emerged in numerous attempts to a theory of quantum gravity and predicts the existence of a minimum length in Nature. In this work, we consider two cosmological models arising from Friedmann equations modified by the GUP (in its linear and quadratic formulations) and compare them with observational data. Our aim is to derive constraints on the GUP parameter and discuss the viability and physical implications of such models. We find for the parameter in the quadratic formulation the constraint $$\alpha ^{2}_{Q}<10^{59}$$ α Q 2 < 10 59 (tighter than most of those obtained in an astrophysical context) while the linear formulation does not appear compatible with present cosmological data. Our analysis highlights the powerful role of high-precision cosmological probes in the realm of quantum gravity phenomenology.

scholarly journals DUALISM BETWEEN PHYSICAL FRAMES AND TIME IN QUANTUM GRAVITY

2004 ◽  
Vol 19 (20) ◽  
pp. 1519-1527 ◽  
Author(s):  
SIMONE MERCURI ◽  
GIOVANNI MONTANI
Keyword(s):  
Quantum Gravity ◽  
Reference Frame ◽  
Path Integral ◽  
Classical Limit ◽  
Quantum Dynamics ◽  
Einstein Equations ◽  
Quantum Level ◽  
Dust Fluid ◽  
Lapse Function ◽  
Canonical Quantum

In this work we present a discussion of the existing links between the procedures of endowing the quantum gravity with a real time and of including in the theory a physical reference frame. More precisely, as a first step, we develop the canonical quantum dynamics, starting from the Einstein equations in presence of a dust fluid and arrive at a Schrödinger evolution. Then, by fixing the lapse function in the path-integral of gravity, we get a Schrödinger quantum dynamics, of which eigenvalues problem provides the appearance of a dust fluid in the classical limit. The main issue of our analysis is to claim that a theory, in which the time displacement invariance, on a quantum level, is broken, is indistinguishable from a theory for which this symmetry holds, but a real reference fluid is included.

scholarly journals QUANTUM RIEMANN SURFACES, 2-D GRAVITY AND THE GEOMETRICAL ORIGIN OF MINIMAL MODELS

1994 ◽  
Vol 09 (31) ◽  
pp. 2871-2878 ◽  
Author(s):  
MARCO MATONE
Keyword(s):  
Quantum Gravity ◽  
Classical Limit ◽  
Riemann Surfaces ◽  
Ward Identity ◽  
Riemann Sphere ◽  
Projective Connection ◽  
Minimal Models ◽  
Standard Representation ◽  
Basic Object ◽  
Liouville Action

Based on a recent paper by Takhtajan, we propose a formulation of 2-D quantum gravity whose basic object is the Liouville action on the Riemann sphere Σ0, m+n with both parabolic and elliptic points. The identification of the classical limit of the conformal Ward identity with the Fuchsian projective connection on Σ0, m+n implies a relation between conformal weights and ramification indices. This formulation works for arbitrary d and admits a standard representation only for d ≤ 1. Furthermore, it turns out that the integerness of the ramification number constrains d = 1 − 24/(n2 − 1) that for n = 2m + 1 coincides with the unitary minimal series of CFT.

scholarly journals SPIN-CUBE MODELS OF QUANTUM GRAVITY

2013 ◽  
Vol 25 (10) ◽  
pp. 1343008 ◽  
Author(s):  
A. MIKOVIĆ
Keyword(s):  
Models Of Quantum Gravity ◽  
Quantum Gravity ◽  
Path Integral ◽  
Classical Limit ◽  
Edge Length ◽  
The State ◽  
Regge Model ◽  
Bf Theory ◽  
Spin Foam Models ◽  
Spin Foam

We study the state-sum models of quantum gravity based on a representation 2-category of the Poincaré 2-group. We call them spin-cube models, since they are categorical generalizations of spin-foam models. A spin-cube state sum can be considered as a path integral for a constrained 2-BF theory, and depending on how the constraints are imposed, a spin-cube state sum can be reduced to a path integral for the area-Regge model with the edge-length constraints, or to a path integral for the Regge model. We also show that the effective actions for these spin-cube models have the correct classical limit.

scholarly journals New insights into quantum gravity from gauge/gravity duality

2016 ◽  
Vol 25 (12) ◽  
pp. 1643002 ◽  
Author(s):  
Netta Engelhardt ◽  
Gary T. Horowitz
Keyword(s):  
Field Theory ◽  
Black Hole ◽  
Quantum Gravity ◽  
Classical Limit ◽  
Cosmic Censorship ◽  
Singularity Theorem ◽  
Gauge Gravity ◽  
Gravity Duality

Using gauge/gravity duality, we deduce several nontrivial consequences of quantum gravity from simple properties of the dual field theory. These include: (1) a version of cosmic censorship, (2) restrictions on evolution through black hole singularities, and (3) the exclusion of certain cosmological bounces. In the classical limit, the latter implies a new singularity theorem.

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