Loop Quantum Gravity and planck Scale Phenomenology

2005 ◽  
pp. 363-408 ◽  
Author(s):  
L. Smolin
Keyword(s):  
Quantum Gravity ◽  
Loop Quantum Gravity ◽  
Planck Scale

scholarly journals Black Hole Interior from Loop Quantum Gravity

2008 ◽  
Vol 2008 ◽  
pp. 1-12 ◽  
Author(s):  
Leonardo Modesto
Keyword(s):  
Black Hole ◽  
Quantum Gravity ◽  
Event Horizon ◽  
Loop Quantum Gravity ◽  
Planck Scale ◽  
Semiclassical Analysis ◽  
Schwarzschild Solution ◽  
Quantum Black Hole ◽  
Minimum Value ◽  
Black Hole Interior

We calculate modifications to the Schwarzschild solution by using a semiclassical analysis of loop quantum black hole. We obtain a metric inside the event horizon that coincides with the Schwarzschild solution near the horizon but that is substantially different at the Planck scale. In particular, we obtain a bounce of theS2sphere for a minimum value of the radius and that it is possible to have another event horizon close to ther=0point.

scholarly journals PROPOSAL OF A SECOND GENERATION OF QUANTUM-GRAVITY-MOTIVATED LORENTZ-SYMMETRY TESTS: SENSITIVITY TO EFFECTS SUPPRESSED QUADRATICALLY BY THE PLANCK SCALE

2003 ◽  
Vol 12 (09) ◽  
pp. 1633-1639 ◽  
Author(s):  
GIOVANNI AMELINO-CAMELIA
Keyword(s):  
Quantum Gravity ◽  
Second Generation ◽  
Loop Quantum Gravity ◽  
Planck Scale ◽  
Cosmic Ray ◽  
Lorentz Symmetry ◽  
Planck Length ◽  
Satisfactory Description ◽  
Symmetry Tests ◽  
Quantum Spacetime

Over the last few years the study of possible Planck-scale departures from classical Lorentz symmetry has been one of the most active areas of quantum-gravity research. We now have a satisfactory description of the fate of Lorentz symmetry in the most popular noncommutative spacetimes and several studies have been devoted to the fate of Lorentz symmetry in loop quantum gravity. Remarkably there are planned experiments with enough sensitivity to reveal these quantum-spacetime effects, if their magnitude is only linearly suppressed by the Planck length. Unfortunately, in some quantum-gravity scenarios even the strongest quantum-spacetime effects are suppressed by at least two powers of the Planck length, and many authors have argued that it would be impossible to test these quadratically-suppressed effects. I here observe that advanced cosmic-ray observatories and neutrino observatories can provide the first elements of an experimental programme testing the possibility of departures from Lorentz symmetry that are quadratically Planck-length suppressed.

scholarly journals Prelude to Simulations of Loop Quantum Gravity on Adiabatic Quantum Computers

2021 ◽  
Vol 8 ◽  
Author(s):  
Jakub Mielczarek
Keyword(s):  
Quantum Gravity ◽  
Loop Quantum Gravity ◽  
Planck Scale ◽  
Quantum Computers ◽  
Hamiltonian Constraint ◽  
Spin Network ◽  
Quantum Processor ◽  
Network States ◽  
D Wave ◽  
Planck Scale Physics

The article addresses the possibility of implementing spin network states, used in the loop quantum gravity approach to Planck scale physics on an adiabatic quantum computer. The discussion focuses on applying currently available technologies and analyzes a concrete example of a D-Wave machine. It is introduced a class of simple spin network states which can be implemented on the Chimera graph architecture of the D-Wave quantum processor. However, extension beyond the currently available quantum processor topologies is required to simulate more sophisticated spin network states. This may inspire new generations of adiabatic quantum computers. A possibility of simulating loop quantum gravity is discussed, and a method of solving a graph non-changing scalar (Hamiltonian) constraint with the use of adiabatic quantum computations is proposed. The presented results establish a basis for the future simulations of Planck scale physics, specifically quantum cosmological configurations, on quantum annealers.

The holographic principle, the equipartition of energy and Newton’s gravity

2017 ◽  
Vol 32 (39) ◽  
pp. 1771003
Author(s):  
M. Sadiq
Keyword(s):  
Quantum Gravity ◽  
Free Parameter ◽  
Loop Quantum Gravity ◽  
Planck Scale ◽  
Scale Factor ◽  
Holographic Principle ◽  
Entropic Force ◽  
Classical Gravity ◽  
Equipartition Of Energy

Assuming the equipartition of energy to hold on a holographic sphere, Erik Verlinde demonstrated that Newton’s gravity follows as an entropic force. Some comments are in place about Verlinde’s assumptions in his derivation. It is pointed out that the holographic principle allows for freedom up to a free scale factor in the choice of Planck scale area while leading to classical gravity. Similarity of this free parameter with the Immirzi parameter of loop quantum gravity is discussed. We point out that the equipartition of energy is inbuilt into the holographic principle and, therefore, need not be assumed from the outset.

scholarly journals QUANTUM STRUCTURE OF GEOMETRY: LOOPY AND FUZZY?

2008 ◽  
Vol 17 (03n04) ◽  
pp. 445-451 ◽  
Author(s):  
ALEJANDRO CORICHI ◽  
JOSÉ A. ZAPATA
Keyword(s):  
Quantum Theory ◽  
Quantum Gravity ◽  
Loop Quantum Gravity ◽  
Planck Scale ◽  
Central Issue ◽  
Quantum Geometry ◽  
Quantum Structure ◽  
One Dimensional ◽  
Algebraic Properties ◽  
Definition Of

In any attempt to build a quantum theory of gravity, a central issue is to unravel the structure of space–time at the smallest scale. Of particular relevance is the possible definition of physical coordinate functions within the theory and the study of their algebraic properties, such as noncommutativity. Here we approach this issue from the perspective of loop quantum gravity and the picture of quantum geometry that the formalism offers. In particular, as we argue here, this emerging picture has two main elements: (i) the nature of the quantum geometry at the Planck scale is one-dimensional, and polymeric with quantized geometrical quantities; and (ii) appropriately defined operators corresponding to coordinates by means of intrinsic, relational constructions become noncommuting. This particular feature of the operators, which operationally localize points on space, gives rise to an emerging geometry that is also, in a precise sense, fuzzy.

scholarly journals On the UV Dimensions of Loop Quantum Gravity

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Michele Ronco
Keyword(s):  
Quantum Gravity ◽  
Quantum Correction ◽  
Loop Quantum Gravity ◽  
Planck Scale ◽  
Space Time ◽  
Two Dimensions ◽  
Quantum Corrections ◽  
Independent Effect ◽  
Modified Dispersion Relation ◽  
Model Independent

Planck-scale dynamical dimensional reduction is attracting more and more interest in the quantum-gravity literature since it seems to be a model independent effect. However, different studies base their results on different concepts of space-time dimensionality. Most of them rely on thespectraldimension; others refer to theHausdorffdimension; and, very recently, thethermaldimension has also been introduced. We here show that all these distinct definitions of dimension give the same outcome in the case of the effective regime of Loop Quantum Gravity (LQG). This is achieved by deriving a modified dispersion relation from the hypersurface-deformation algebra with quantum corrections. Moreover, we also observe that the number of UV dimensions can be used to constrain the ambiguities in the choice of these LQG-based modifications of the Dirac space-time algebra. In this regard, introducing thepolymerizationof connections, that is,K→sin⁡δK/δ, we find that the leading quantum correction givesdUV=2.5. This result may indicate that the running to the expected value of two dimensions is ongoing, but it has not been completed yet. FindingdUVat ultrashort distances would require going beyond the effective approach we here present.

scholarly journals Review on hermiticity of the volume operators in Loop Quantum Gravity

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

scholarly journals Neutrino masses, vacuum stability and quantum gravity prediction for the mass of the top quark

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Guillem Domènech ◽  
Mark Goodsell ◽  
Christof Wetterich
Keyword(s):  
Quantum Gravity ◽  
Top Quark ◽  
Quark Mass ◽  
Scalar Potential ◽  
Planck Scale ◽  
Neutrino Masses ◽  
Top Quark Mass ◽  
Vacuum Stability ◽  
Intermediate Scale ◽  
Yukawa Couplings

Abstract A general prediction from asymptotically safe quantum gravity is the approximate vanishing of all quartic scalar couplings at the UV fixed point beyond the Planck scale. A vanishing Higgs doublet quartic coupling near the Planck scale translates into a prediction for the ratio between the mass of the Higgs boson MH and the top quark Mt. If only the standard model particles contribute to the running of couplings below the Planck mass, the observed MH∼ 125 GeV results in the prediction for the top quark mass Mt∼ 171 GeV, in agreement with recent measurements. In this work, we study how the asymptotic safety prediction for the top quark mass is affected by possible physics at an intermediate scale. We investigate the effect of an SU(2) triplet scalar and right-handed neutrinos, needed to explain the tiny mass of left-handed neutrinos. For pure seesaw II, with no or very heavy right handed neutrinos, the top mass can increase to Mt ∼ 172.5 GeV for a triplet mass of M∆ ∼ 108GeV. Right handed neutrino masses at an intermediate scale increase the uncertainty of the predictions of Mt due to unknown Yukawa couplings of the right-handed neutrinos and a cubic interaction in the scalar potential. For an appropriate range of Yukawa couplings there is no longer an issue of vacuum stability.

scholarly journals Noisy effects in interferometric quantum gravity tests

2017 ◽  
Vol 15 (08) ◽  
pp. 1740014 ◽  
Author(s):  
F. Benatti ◽  
R. Floreanini ◽  
S. Olivares ◽  
E. Sindici
Keyword(s):  
Quantum Gravity ◽  
Weak Coupling ◽  
Scale Effects ◽  
External Environment ◽  
Planck Scale ◽  
Canonical Commutation Relations ◽  
Commutation Relations ◽  
Photon Propagation ◽  
Gravity Theories ◽  
Planck Scale Effects

Quantum-enhanced metrology is boosting interferometer sensitivities to extraordinary levels, up to the point where table-top experiments have been proposed to measure Planck-scale effects predicted by quantum gravity theories. In setups involving multiple photon interferometers, as those for measuring the so-called holographic fluctuations, entanglement provides substantial improvements in sensitivity. Entanglement is however a fragile resource and may be endangered by decoherence phenomena. We analyze how noisy effects arising either from the weak coupling to an external environment or from the modification of the canonical commutation relations in photon propagation may affect this entanglement-enhanced gain in sensitivity.

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