scholarly journals Four-dimensional spinfoam quantum gravity with a cosmological constant: Finiteness and semiclassical limit

2021 ◽  
Vol 104 (10) ◽  
Author(s):  
Muxin Han
Keyword(s):  
Quantum Gravity ◽  
Cosmological Constant ◽  
Semiclassical Limit

scholarly journals MEASUREMENTS AND INFORMATION IN SPIN FOAM MODELS

2012 ◽  
Vol 27 (28) ◽  
pp. 1250164
Author(s):  
J. MANUEL GARCÍA-ISLAS
Keyword(s):  
Information Theory ◽  
Quantum Gravity ◽  
Cosmological Constant ◽  
Shannon Entropy ◽  
Three Dimensional ◽  
Spin Network ◽  
Spin Foam Models ◽  
Foam Model ◽  
Spin Foam Model ◽  
Spin Foam

In the three-dimensional spin foam model of quantum gravity with a cosmological constant, there exists a set of observables associated with spin network graphs. A set of probabilities is calculated from these observables, and hence the associated Shannon entropy can be defined. We present the Shannon entropy associated with these observables and find some interesting bounded inequalities. The problem relates measurements, entropy and information theory in a simple way which we explain.

scholarly journals TIME, VACUUM ENERGY, AND THE COSMOLOGICAL CONSTANT

2009 ◽  
Vol 18 (14) ◽  
pp. 2265-2268 ◽  
Author(s):  
VIQAR HUSAIN
Keyword(s):  
Quantum Gravity ◽  
Cosmological Constant ◽  
Vacuum Energy ◽  
Cosmological Constant Problem ◽  
Problem Of Time ◽  
The Relationship

We describe a link between the cosmological constant problem and the problem of time in quantum gravity. This arises from examining the relationship between the cosmological constant and vacuum energy in light of nonperturbative formulations of quantum gravity.

scholarly journals Prediction for the cosmological constant and constraints on SUSY GUTs in resummed quantum gravity

2018 ◽  
Vol 33 (29) ◽  
pp. 1830028
Author(s):  
B. F. L. Ward
Keyword(s):  
General Theory ◽  
Quantum Gravity ◽  
Cosmological Constant ◽  
Uncertainty Principle ◽  
Planck Scale ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Heisenberg Uncertainty Principle ◽  
Heisenberg Uncertainty

Working in the context of the Planck scale cosmology formulation of Bonanno and Reuter, we use our resummed quantum gravity approach to Einstein’s general theory of relativity to estimate the value of the cosmological constant as [Formula: see text]. We show that SUSY GUT models are constrained by the closeness of this estimate to experiment. We also address various consistency checks on the calculation. In particular, we use the Heisenberg uncertainty principle to remove a large part of the remaining uncertainty in our estimate of [Formula: see text].

scholarly journals Einstein–Heisenberg consistency condition interplay with cosmological constant prediction in resummed quantum gravity

2015 ◽  
Vol 30 (38) ◽  
pp. 1550206 ◽  
Author(s):  
B. F. L. Ward
Keyword(s):  
Quantum Gravity ◽  
Cosmological Constant ◽  
Promising Result ◽  
Consistency Condition ◽  
Planck Scale ◽  
Theory Of Relativity ◽  
Heisenberg Uncertainty Principle ◽  
Recent Success ◽  
Heisenberg Uncertainty ◽  
Frw Model

We argue that our recent success in using our resummed quantum gravity (RQG) approach to Einstein’s general theory of relativity, in the context of the Planck scale cosmology formulation of Bonanno and Reuter, to estimate the value of the cosmological constant [Formula: see text] supports the use of quantum mechanical consistency requirements to constrain the main uncertainty in that very promising result. This main uncertainty, which is due to the uncertainty in the value of the time [Formula: see text] at which the transition from the Planck scale cosmology to the FRW model occurs, is shown to be reduced, by requiring consistency between the Heisenberg uncertainty principle and the known properties of the solutions of Einstein’s equations, from four orders of magnitude to the level of a factor of [Formula: see text]. This lends more credibility to the overall RQG approach itself, in general, and to our estimate of [Formula: see text] in particular.

scholarly journals The Quantum Cosmological Constant

Symmetry ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1130 ◽  
Author(s):  
Stephon Alexander ◽  
Joao Magueijo ◽  
Lee Smolin
Keyword(s):  
General Relativity ◽  
Quantum Theory ◽  
Quantum Gravity ◽  
Cosmological Constant ◽  
Uncertainty Relation ◽  
Time Variable ◽  
Transition Functions ◽  
New Interpretation ◽  
Chern Simons

We present an extension of general relativity in which the cosmological constant becomes dynamical and turns out to be conjugate to the Chern–Simons invariant of the Ashtekar connection on a spatial slicing. The latter has been proposed Soo and Smolin as a time variable for quantum gravity: the Chern–Simons time. In the quantum theory, the inverse cosmological constant and Chern–Simons time will then become conjugate operators. The “Kodama state” gets a new interpretation as a family of transition functions. These results imply an uncertainty relation between Λ and Chern–Simons time; the consequences of which will be discussed elsewhere.

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