Probing Spacetime Foam with Extragalactic Sources

Christiansen, W. A.; Ng, Y. Jack; Dam, H. van

doi:10.1103/physrevlett.96.051301

Cited by 77 publications

(47 citation statements)

References 32 publications

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“…Satisfactorily, this falls within the general expectations for the form of distance fuzziness δL (L Pl ) α L 1−α discussed in previous works 4,5,20,21 . Equation (1) bridges two areas of investigation in quantum gravity: one on stochastic speed-of-light variations and one on a minimum-uncertainty principle for distance measurements.…”

supporting

confidence: 89%

“…Equation (1) bridges two areas of investigation in quantum gravity: one on stochastic speed-of-light variations and one on a minimum-uncertainty principle for distance measurements. For purposes of exploiting this to perform indirect tests for stochastic speed-of-light variations, one should take notice that the best method to date for testing distance fuzziness relies on its implications on the formation of halo structures in the images of distant quasars 5 . However, the outcome of those studies depends rather crucially 5 on the particular form of the fluctuations of the light-cone in the direction transverse to the one of propagation, in the same sense that our stochastic speed-of-light variations could be modelled purely in terms of fluctuations of the light-cone along the direction of propagation.…”

mentioning

confidence: 99%

“…For purposes of exploiting this to perform indirect tests for stochastic speed-of-light variations, one should take notice that the best method to date for testing distance fuzziness relies on its implications on the formation of halo structures in the images of distant quasars 5 . However, the outcome of those studies depends rather crucially 5 on the particular form of the fluctuations of the light-cone in the direction transverse to the one of propagation, in the same sense that our stochastic speed-of-light variations could be modelled purely in terms of fluctuations of the light-cone along the direction of propagation. Any attempt to test stochastic speedof-light variations on the basis of such quasar-image studies would only produce 'conditional limits' , affected by assumptions about the fluctuations of the light-cone in the direction orthogonal to the propagation.…”

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confidence: 99%

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A Planck-scale limit on spacetime fuzziness and stochastic Lorentz invariance violation

et al. 2015

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Wheeler's 'spacetime-foam' 1 picture of quantum gravity (QG) suggests spacetime fuzziness (fluctuations leading to nondeterministic e ects) at distances comparable to the Planck length, L Pl ≈ 1.62 × 10 −33 cm, the inverse (in natural units) of the Planck energy, E Pl ≈ 1.22 × 10 19 GeV. The resulting nondeterministic motion of photons on the Planck scale is expected to produce energy-dependent stochastic fluctuations in their speed. Such a stochastic deviation from the well-measured speed of light at low photon energies, c, should be contrasted with the possibility of an energy-dependent systematic, deterministic deviation. Such a systematic deviation, on which observations by the Fermi satellite set Planck-scale limits for linear energy dependence 2 , is more easily searched for than stochastic deviations. Here, for the first time, we place Planckscale limits on the more generic spacetime-foam prediction of energy-dependent fuzziness in the speed of photons. Using high-energy observations from the Fermi Large Area Telescope (LAT) of gamma-ray burst GRB090510, we test a model in which photon speeds are distributed normally around c with a standard deviation proportional to the photon energy. We constrain the model's characteristic energy scale beyond the Planck scale at >2.8E Pl (>1.6E Pl ), at 95% (99%) confidence. Our results set a benchmark constraint to be reckoned with by any QG model that features spacetime quantization.Significant advances in exploring QG-motivated phenomenology 3 have been achieved in the past decade. In some cases, it was possible to establish bounds on QG effects at the Planck scale. Among the possible QG effects, it is expected 4-6 that the postulated foamy/fuzzy structure of spacetime at short distances would induce a stochastic effect, where two massless particles of equal energy travel the exact same distance in different times. In this work, we examine a model of spacetime foam 6 , in which quantum fluctuations of spacetime near the Planck scale induce stochastic variations in the speed of light, v(E) = c + δv(E), where δv(E) is random and distributed normally around zero with a standard deviationns c. In this model, we observationally expect a bunch of photons of equal energy E emitted simultaneously from a distant astrophysical source to propagate with different speeds and arrive at different times, normally distributed around the light travel time T for v(E) = c, with a standard deviation σ T (E) = T c σ v (E)/c, where T c ∼ T is given by 7 : This stochastic speed-of-light variation is in conflict with Lorentz invariance, the basic symmetry of Einstein's theory of relativity. Such a conflict is usually referred to as Lorentz invariance violation (LIV). Here, we examine a simple manifestation of 'stochastic LIV' , in which the light-cone of special relativity still exists; however it is fuzzy. The dimensionless parameter ξ s,ns determines the energy scale ξ s,ns E Pl of stochastic LIV, and the model-dependent parameter n s determines the leading-order energy dependence of the e...

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confidence: 99%

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confidence: 99%

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A Planck-scale limit on spacetime fuzziness and stochastic Lorentz invariance violation

et al. 2015

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“…We point out that such a correction corresponds to the decomposition over the small parameter kl 1, where l has the sense of a characteristic scale connected to wormholes 3 , which leads to a very strong limit on the existence of microscopic wormholes (i.e., we may admit only the existence of wormholes at scales l 1 < L Pl ; see also analogous estimates in [36,37]). …”

Section: Lorentz Invariance and The Dispersion Relationsmentioning

confidence: 86%

“…All the existing estimates coincide in the order of magnitude and concern only extremely small scales [33][34][35]. In particular, in a recent paper [35], the strongest limit for the "first" correction to the standard dispersion relation was established (e.g., see also [34,36,37]). Namely,…”

Section: Lorentz Invariance and The Dispersion Relationsmentioning

confidence: 98%

Effects of Scattering of Radiation on Wormholes

Кириллов

Савелова

2018

Universe

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Significant progress in the development of observational techniques gives us the hope to directly observe cosmological wormholes. We have collected basic effects produced by the scattering of radiation on wormholes, which can be used in observations. These are the additional topological damping of cosmic rays, the generation of a diffuse background around any discrete source, the generation of an interference picture, and distortion of the cosmic microwave background (CMB) spectrum. It turns out that wormholes in the leading order mimic perfectly analogous effects of the scattering of radiation on the standard matter (dust, hot electron gas, etc.). However, in higher orders, a small difference appears, which allows for disentangling effects of wormholes and ordinary matter.

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Observational Constraints on Local Lorentz Invariance

Bluhm

2014

Springer Handbooks

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The idea that local Lorentz invariance might be violated due to new physics that goes beyond the Standard Model of particle physics and Einstein's General Relativity has received a great deal of interest in recent years. At the same time, new experiments have been designed and conducted that are able to test Lorentz symmetry at unprecedented levels. Much of this theoretical and experimental progress has been driven by the development of the framework for investigating Lorentz violation known as the Standard Model Extension (SME). The SME is the lagrangian-based effective field theory that by definition contains all Lorentz-violating interaction terms that can be written as observer scalars involving particle fields in the Standard Model and gravitational fields in a generalized theory of gravity. This includes all terms that could arise from a process of spontaneous Lorentz violation as well as terms that explicitly break Lorentz symmetry. In this article, an overview of the SME is presented, including its motivations and construction. A very useful minimal version of the SME in Minkowski spacetime that maintains gauge invariance and power-counting renormalizability is constructed as well. Data tables summarizing tests of local Lorentz invariance for the different particle sectors in the Standard Model and with gravity are maintained by Kostelecký's group at Indiana University. A partial survey of these tests, including some of the high-precision sensitivities they attain, is presented here.

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Probing Spacetime Foam with Extragalactic Sources

Cited by 77 publications

References 32 publications

A Planck-scale limit on spacetime fuzziness and stochastic Lorentz invariance violation

A Planck-scale limit on spacetime fuzziness and stochastic Lorentz invariance violation

Effects of Scattering of Radiation on Wormholes

Observational Constraints on Local Lorentz Invariance

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