scholarly journals Comparing Quantum Gravity Models: String Theory, Loop Quantum Gravity, and Entanglement Gravity versus SU(∞)-QGR

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 58
Author(s):  
Houri Ziaeepour

In a previous article we proposed a new model for quantum gravity (QGR) and cosmology, dubbed SU(∞)-QGR. One of the axioms of this model is that Hilbert spaces of the Universe and its subsystems represent the SU(∞) symmetry group. In this framework, the classical spacetime is interpreted as being the parameter space characterizing states of the SU(∞) representing Hilbert spaces. Using quantum uncertainty relations, it is shown that the parameter space—the spacetime—has a 3+1 dimensional Lorentzian geometry. Here, after a review of SU(∞)-QGR, including a demonstration that its classical limit is Einstein gravity, we compare it with several QGR proposals, including: string and M-theories, loop quantum gravity and related models, and QGR proposals inspired by the holographic principle and quantum entanglement. The purpose is to find their common and analogous features, even if they apparently seem to have different roles and interpretations. The hope is that this exercise provides a better understanding of gravity as a universal quantum force and clarifies the physical nature of the spacetime. We identify several common features among the studied models: the importance of 2D structures; the algebraic decomposition to tensor products; the special role of the SU(2) group in their formulation; the necessity of a quantum time as a relational observable. We discuss how these features can be considered as analogous in different models. We also show that they arise in SU(∞)-QGR without fine-tuning, additional assumptions, or restrictions.

2015 ◽  
Vol 92 (12) ◽  
Author(s):  
Aurelien Barrau ◽  
Xiangyu Cao ◽  
Karim Noui ◽  
Alejandro Perez

2018 ◽  
Vol 778 ◽  
pp. 184-189 ◽  
Author(s):  
Suddhasattwa Brahma ◽  
Michele Ronco

2008 ◽  
Vol 17 (13n14) ◽  
pp. 2475-2484
Author(s):  
JOHN SWAIN

Objects exhibiting statistics other than the familiar Bose and Fermi ones are natural in theories with topologically nontrivial objects, including geons, strings, and black holes. It is argued here from several viewpoints that the statistics of ordinary particles with which we are already familiar are likely to be modified due to quantum gravity effects. In particular, such modifications are argued to be present in loop quantum gravity and in any theory which represents space–time in a fundamentally piecewise-linear fashion or, more generally, which has large curvature fluctuations at small scales. The appearance of unusual statistics may be a generic feature (such as the deformed position–momentum uncertainty relations and the appearance of a fundamental length scale) which is to be expected in any theory of quantum gravity, and which could be testable.


2019 ◽  
Vol 51 (5) ◽  
Author(s):  
S. Ariwahjoedi ◽  
I. Husin ◽  
I. Sebastian ◽  
F. P. Zen

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Sung-Sik Lee

Abstract Einstein’s theory of general relativity is based on the premise that the physical laws take the same form in all coordinate systems. However, it still presumes a preferred decomposition of the total kinematic Hilbert space into local kinematic Hilbert spaces. In this paper, we consider a theory of quantum gravity that does not come with a preferred partitioning of the kinematic Hilbert space. It is pointed out that, in such a theory, dimension, signature, topology and geometry of spacetime depend on how a collection of local clocks is chosen within the kinematic Hilbert space.


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