scholarly journals The Cosmological Constant in Distorted Quantum Cosmology

2016 ◽  
Author(s):  
Remo Garattini
Keyword(s):  
Cosmological Constant ◽  
Quantum Cosmology

scholarly journals Bootstrapped Newtonian Cosmology and the Cosmological Constant Problem

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 358
Author(s):  
Roberto Casadio ◽  
Andrea Giusti
Keyword(s):  
Black Holes ◽  
Cosmological Constant ◽  
Quantum Cosmology ◽  
Quantum Physics ◽  
Gravitational Interaction ◽  
Newtonian Gravity ◽  
Cosmological Constant Problem ◽  
Newtonian Cosmology ◽  
Natural Solution ◽  
The Impact

Bootstrapped Newtonian gravity was developed with the purpose of estimating the impact of quantum physics in the nonlinear regime of the gravitational interaction, akin to corpuscular models of black holes and inflation. In this work, we set the ground for extending the bootstrapped Newtonian picture to cosmological spaces. We further discuss how such models of quantum cosmology can lead to a natural solution to the cosmological constant problem.

scholarly journals p-ADIC AND ADELIC MINISUPERSPACE QUANTUM COSMOLOGY

2002 ◽  
Vol 17 (10) ◽  
pp. 1413-1433 ◽  
Author(s):  
GORAN S. DJORDJEVIĆ ◽  
BRANKO DRAGOVICH ◽  
LJUBIŠA D. NEŠIĆ ◽  
IGOR V. VOLOVICH
Keyword(s):  
Quantum Mechanics ◽  
Cosmological Constant ◽  
Quantum Cosmology ◽  
Quantum Effects ◽  
De Sitter Space ◽  
Cosmological Models ◽  
De Sitter ◽  
Adelic Quantum Mechanics ◽  
Matter Fields

We consider the formulation and some elaboration of p-adic and adelic quantum cosmology. The adelic generalization of the Hartle–Hawking proposal does not work in models with matter fields. p-adic and adelic minisuperspace quantum cosmology is well defined as an ordinary application of p-adic and adelic quantum mechanics. It is illustrated by a few cosmological models in one, two and three minisuperspace dimensions. As a result of p-adic quantum effects and the adelic approach, these models exhibit some discreteness of the minisuperspace and cosmological constant. In particular, discreteness of the de Sitter space and its cosmological constant is emphasized.

scholarly journals Asymptotically equivalent functions and ultrafilters applied to noncommutative quantum cosmology

2019 ◽  
Vol 65 (5 Sept-Oct) ◽  
pp. 519
Author(s):  
J.A. Astorga-Moreno ◽  
E.A. Mena Barboza ◽  
And M.A. García-Aspeitia
Keyword(s):  
Dynamical System ◽  
Cosmological Constant ◽  
Commutation Relation ◽  
Quantum Cosmology ◽  
Positive Cosmological Constant ◽  
Classical Approximation ◽  
Noncommutative Quantum

Using the semi-classical approximation to the Wheeler-DeWitt equation obtained via Arnowitt-Deser-Misner (ADM) formalism in the Friedmann-Lemaitre-Robertson-Walker (FLRW) model coupled to a scalar eld and positive cosmological constant, and in the Kantowski-Sachs (KS) Universe, we introduced a deformation on the commutation relation for the minisuperspace variables and find an explicit semiclassical expression equivalent, in an adequate limit, to the solution with the aid of asymptotically equal functions and the theory of Ultralters, oering a suggestive alternative to sketch the behavior of the dynamical system involved without the need to solve it numerically.

scholarly journals The Effect of a Positive Cosmological Constant on the Bounce of Loop Quantum Cosmology

Mathematics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 186
Author(s):  
Mercedes Martín-Benito ◽  
Rita B. Neves
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Quantum Cosmology ◽  
Quantum Dynamics ◽  
Solvable Model ◽  
Massless Scalar ◽  
Loop Quantum Cosmology ◽  
Massless Scalar Field ◽  
Positive Cosmological Constant ◽  
Semiclassical States

We provide an analytical solution to the quantum dynamics of a flat Friedmann-Lemaître- Robertson-Walker model with a massless scalar field in the presence of a small and positive cosmological constant, in the context of Loop Quantum Cosmology. We use a perturbative treatment with respect to the model without a cosmological constant, which is exactly solvable. Our solution is approximate, but it is precisely valid at the high curvature regime where quantum gravity corrections are important. We compute explicitly the evolution of the expectation value of the volume. For semiclassical states characterized by a Gaussian spectral profile, the introduction of a positive cosmological constant displaces the bounce of the solvable model to lower volumes and to higher values of the scalar field. These displacements are state dependent, and in particular, they depend on the peak of the Gaussian profile, which measures the momentum of the scalar field. Moreover, for those semiclassical states, the bounce remains symmetric, as in the vanishing cosmological constant case. However, we show that the behavior of the volume is more intricate for generic states, leading in general to a non-symmetric bounce.

COSMIC TIME IN QUANTUM COSMOLOGY: INFLATION-COMPACTIFICATION AS A QUANTUM EFFECT

1993 ◽  
Vol 02 (02) ◽  
pp. 221-247 ◽  
Author(s):  
E.I. GUENDELMAN ◽  
A.B. KAGANOVICH
Keyword(s):  
Cosmological Constant ◽  
Quantum Cosmology ◽  
Quantum Effect ◽  
Cosmic Time ◽  
Expectation Values ◽  
Cosmological Singularity ◽  
Inflationary Phase ◽  
Definition Of ◽  
The Universe ◽  
Kaluza Klein

We consider 1+D-dimensional, toroidally compact Kaluza-Klein theories. In the context of the minisuperspace approach of quantum cosmology, we solve the Wheeler-DeWitt equation in the presence of a negative cosmological constant and dust. Then, it is found that the quantum effects stabilize the volume of the Universe, so that there can be an avoidance of the cosmological singularity. Although cosmic time does not appear explicitly in the Wheeler-DeWitt equation, we find that a cosmic time dependence appears for the expectation values of certain variables. This result is obtained when proper care of some subtle points concerning the definition of averages in this model is taken. The stabilization of the volume, when there is anisotropy in the evolution of the Universe (which turns out to be quantized), is consistent with another effect we find: the existence of a “quantum inflationary phase” for some dimensions and simultaneously the existence of a “quantum deflationary contraction” for the rest.

scholarly journals Revisiting the Cosmological Constant Problem within Quantum Cosmology

Universe ◽  
2020 ◽  
Vol 6 (8) ◽  
pp. 108
Author(s):  
Vesselin Gueorguiev ◽  
Andre Maeder
Keyword(s):  
Energy Density ◽  
Cosmological Constant ◽  
Quantum Cosmology ◽  
Vacuum Energy ◽  
Planck Scale ◽  
Vacuum Energy Density ◽  
Characteristic Scale ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Cosmological Constant Problem

A new perspective on the Cosmological Constant Problem (CCP) is proposed and discussed within the multiverse approach of Quantum Cosmology. It is assumed that each member of the ensemble of universes has a characteristic scale a that can be used as integration variable in the partition function. An averaged characteristic scale of the ensemble is estimated by using only members that satisfy the Einstein field equations. The averaged characteristic scale is compatible with the Planck length when considering an ensemble of solutions to the Einstein field equations with an effective cosmological constant. The multiverse ensemble is split in Planck-seed universes with vacuum energy density of order one; thus, Λ˜≈8π in Planck units and a-derivable universes. For a-derivable universe with a characteristic scale of the order of the observed Universe a≈8×1060, the cosmological constant Λ=Λ˜/a2 is in the range 10−121–10−122, which is close in magnitude to the observed value 10−123. We point out that the smallness of Λ can be viewed to be natural if its value is associated with the entropy of the Universe. This approach to the CCP reconciles the Planck-scale huge vacuum energy–density predicted by QFT considerations, as valid for Planck-seed universes, with the observed small value of the cosmological constant as relevant to an a-derivable universe as observed.

scholarly journals SIGNATURE CHANGE IN NONCOMMUTATIVE FRW COSMOLOGY

2012 ◽  
Vol 27 (37) ◽  
pp. 1250214 ◽  
Author(s):  
T. GHANEH ◽  
F. DARABI ◽  
H. MOTAVALLI
Keyword(s):  
Cosmological Constant ◽  
Quantum Cosmology ◽  
Physical Parameters ◽  
Continuous Change ◽  
Frw Cosmology ◽  
Noncommutative Phase Space ◽  
Good Correspondence ◽  
Signature Change ◽  
Classical Quantum ◽  
Quantum Correspondence

The conditions for which the no boundary proposal may have a classical realization of a continuous change of signature, are investigated for a cosmological model described by FRW metric coupled with a self-interacting scalar field, having a noncommutative phase space of dynamical variables. The model is then quantized and a good correspondence is shown between the classical and quantum cosmology indicating that the noncommutativity does not destruct the classical-quantum correspondence. It is also shown that the quantum cosmology supports a signature transition where the bare cosmological constant takes a vast continuous spectrum of negative values. The bounds of bare cosmological constant are limited by the values of noncommutative parameters. Moreover, it turns out that the physical parameters are constrained by the noncommutativity parameters.

scholarly journals High-order quantum back-reaction and quantum cosmology with a positive cosmological constant

2011 ◽  
Vol 84 (4) ◽  
Author(s):  
Martin Bojowald ◽  
David Brizuela ◽  
Hector H. Hernández ◽  
Michael J. Koop ◽  
Hugo A. Morales-Técotl
Keyword(s):  
Cosmological Constant ◽  
Quantum Cosmology ◽  
High Order ◽  
Back Reaction ◽  
Positive Cosmological Constant
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