The Spectral Dimension of the Universe is Scale Dependent

Ambjørn, J.; Jurkiewicz, J.; Loll, R.

doi:10.1103/physrevlett.95.171301

Cited by 493 publications

(859 citation statements)

References 13 publications

(32 reference statements)

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“…In particular it has been shown [6,22] that these spacetimes have fractal properties, with a fractal dimension of 2 at small, and 4 at large distances. The same dynamical dimensional reduction was also observed in numerical studies of Lorentzian dynamical triangulations [25][26][27] and in [28] A.Connes et al speculated about its possible relevance to the non-commutative geometry of the standard model.…”

Section: Introductionsupporting

confidence: 58%

Astrophysical implications of the Asymptotic Safety Scenario in Quantum Gravity

Bonanno¹

2011

Proceedings of Workshop on Continuum and Lattice Approaches to Quantum Gravity — PoS(CLAQG08)

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In recent years it has emerged that the high energy behavior of gravity could be governed by an ultraviolet non-Gaussian fixed point of the (dimensionless) Newton's constant, whose behavior at high energy is thus antiscreened. This phenomenon has several astrophysical implications. In particular in this article recent works on renormalization group improved cosmologies based upon a renormalization group trajectory of Quantum Einstein Gravity with realistic parameter values will be reviewed. It will be argued that quantum effects can account for the entire entropy of the present Universe in the massless sector and give rise to a phase of inflationary expansion. Moreover, the prediction for the final state of the black hole evaporation, is a Planck size remnant which is formed in an infinite time. Workshop on Continuum and Lattice Approaches to Quantum Gravity

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Section: Introductionsupporting

confidence: 58%

Astrophysical implications of the Asymptotic Safety Scenario in Quantum Gravity

Bonanno¹

2011

Proceedings of Workshop on Continuum and Lattice Approaches to Quantum Gravity — PoS(CLAQG08)

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“…The dimension reduction mechanism from 4d to 2d in gravitational system is critical for the non-perturbative renormalizability and the existence of a non-Gaussian fixed point which is suggested by literature [20][21][22][23][24][25][26][27]. The difference between those and ours is that it is the dimension reduction of d of the base space of the NLSM but the physical spacetime dimension D of the target space, although they are related in the semi-classical approximation.…”

Section: Quantum Behaviormentioning

confidence: 79%

The Cosmological Constant Problem and Quantum Spacetime Reference Frame

Luo¹

2017

Preprint

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We generalize the idea of quantum clock time to quantum spacetime reference frame via physical realization of a reference system by quantum rulers and clocks. Omitting the internal degrees of freedom (such as spins) of the physical rulers and clocks, only considering their metric properties, the spacetime reference frame is described by a bosonic non-linear sigma model. We study the quantum behavior of the system under approximations, and obtain (1) a cosmological constant valued (2/π)ρc0 (ρc0 the critical density at near current epoch) which is very close to the observations; (2) an effective Einstein-Hilbert term in the effective action; (3) the ratio of variance to mean-squared of spacetime interval tends to a universal constant 2/π in the infrared region. This effect is testable by observing a linear dependence between the inherent quantum variance and mean-squared of the redshifts from cosmic distant spectral lines. The proportionality is expected to be the observed percentage of the dark energy. We also generalize the equivalence principle to be valid for all quantum phenomenon.

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“…8 G is symmetric and bilinear with non-negative eigenvalues, but has degeneracies at some points g ∈ SOð4Þ.…”

Section: Methodsmentioning

confidence: 99%

“…We do not require them to be related explicitly to any truly observable phenomenological effects (other than perhaps in some semiclassical limit), which would be a tall order in any theory of quantum gravity. An example of an observable in this looser sense is the (expectation value of the) spectral dimension of quantum spacetime, a quantity which has been measured explicitly in CDT quantum gravity [8], and also studied in other formulations [19].…”

Section: Wilson Lines In Cdtmentioning

confidence: 99%

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Wilson loops in nonperturbative quantum gravity

Ambjørn¹,

Görlich²,

Jurkiewicz³

et al. 2015

Phys. Rev. D

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By explicit construction, we show that one can in a simple way introduce and measure gravitational holonomies and Wilson loops in lattice formulations of nonperturbative quantum gravity based on (causal) dynamical triangulations. We use this setup to investigate a class of Wilson line observables associated with the world line of a point particle coupled to quantum gravity, and deduce from their expectation values that the underlying holonomies cover the group manifold of SO(4) uniformly.

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The Spectral Dimension of the Universe is Scale Dependent

Cited by 493 publications

References 13 publications

Astrophysical implications of the Asymptotic Safety Scenario in Quantum Gravity

Astrophysical implications of the Asymptotic Safety Scenario in Quantum Gravity

The Cosmological Constant Problem and Quantum Spacetime Reference Frame

Wilson loops in nonperturbative quantum gravity

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