Summary of Parallel Session: “Emergent Gravity and Quantum Gravity”

Author(s):  
A. Marcianò
2012 ◽  
Vol 09 (06) ◽  
pp. 1261001 ◽  
Author(s):  
GIOVANNI AMELINO-CAMELIA

I stress that spacetime is a redundant abstraction, since describing the physical content of all so-called "spacetime measurements" only requires timing (by a physical/material clock) of particle detections (at a physical/material detector). It is interesting then to establish which aspects of our current theories afford us the convenient abstraction of a spacetime. I emphasize the role played by the assumed triviality of the geometry of momentum space, which makes room for an observer-independent notion of locality. This is relevant for some recent studies of the quantum-gravity problem that stumbled upon hints of a nontrivial geometry of momentum space, something which had been strikingly envisaged for quantum gravity already in 1938 by Max Born. If indeed momentum space has nontrivial geometry then the abstraction of a spacetime becomes more evidently redundant and less convenient: one may still abstract a spacetime but only allowing for the possibility of a relativity of spacetime locality. I also provide some examples of how all this could affect our attitude toward the quantum-gravity problem, including some for the program of emergent gravity and emergent spacetime. And in order to give an illustrative example of possible logical path for the "disappearance of spacetime" I rely on formulas inspired by the κ-Poincaré framework.


2018 ◽  
Vol 168 ◽  
pp. 03006
Author(s):  
Hyun Seok Yang

We suggest that dark energy and dark matter may be a cosmic uroboros of quantum gravity due to the coherent vacuum structure of spacetime. We apply the emergent gravity to a large N matrix model by considering the vacuum in the noncommutative (NC) Coulomb branch satisfying the Heisenberg algebra. We observe that UV fluctuations in the NC Coulomb branch are always paired with IR fluctuations and these UV/IR fluctuations can be extended to macroscopic scales. We show that space-like fluctuations give rise to the repulsive gravitational force while time-like fluctuations generate the attractive gravitational force. When considering the fact that the fluctuations are random in nature and we are living in the (3+1)-dimensional spacetime, the ratio of the repulsive and attractive components will end in ¾ : ¼= 75 : 25 and this ratio curiously coincides with the dark composition of our current Universe. If one includes ordinary matters which act as the attractive gravitational force, the emergent gravity may explain the dark sector of our Universe more precisely.


2015 ◽  
Vol 30 (04n05) ◽  
pp. 1550016 ◽  
Author(s):  
Hyun Seok Yang

Emergent gravity is based on a novel form of the equivalence principle known as the Darboux theorem or the Moser lemma in symplectic geometry stating that the electromagnetic force can always be eliminated by a local coordinate transformation as far as space–time admits a symplectic structure, in other words, a microscopic space–time becomes noncommutative (NC). If gravity emerges from U(1) gauge theory on NC space–time, this picture of emergent gravity suggests a completely new quantization scheme where quantum gravity is defined by quantizing space–time itself, leading to a dynamical NC space–time. Therefore the quantization of emergent gravity is radically different from the conventional approach trying to quantize a phase space of metric fields. This approach for quantum gravity allows a background-independent formulation where space–time and matter fields are equally emergent from a universal vacuum of quantum gravity.


2019 ◽  
Author(s):  
Vitaly Kuyukov

Many approaches to quantum gravity consider the revision of the space-time geometry and the structure of elementary particles. One of the main candidates is string theory. It is possible that this theory will be able to describe the problem of hierarchy, provided that there is an appropriate Calabi-Yau geometry. In this paper we will proceed from the traditional view on the structure of elementary particles in the usual four-dimensional space-time. The only condition is that quarks and leptons should have a common emerging structure. When a new formula for the mass of the hierarchy is obtained, this structure arises from topological quantum theory and a suitable choice of dimensional units.


2020 ◽  
Author(s):  
Vitaly Kuyukov
Keyword(s):  

Braking effect in quantum gravity


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

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