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

作者：Vasileiou Vlasios^*; Granot Jonathan; Piran Tsvi; Amelino Camelia Giovanni

来源：Nature Physics, 2015, 11(4): 344-346.

DOI：10.1038/NPHYS3270

Wheeler's 'spacetime-foam' 1 picture of quantum gravity (QG) suggests spacetime fuzziness (fluctuations leading to non-deterministic effects) at distances comparable to the Planck length, L-Pl approximate to 1.62 x 10(-33) cm, the inverse (in natural units) of the Planck energy, E-Pl approximate to 1.22 x 10(19) GeV. The resulting non-deterministic 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 Planck-scale 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.

• 出版日期2015-4