Quantum or torsion gravity models predict unusual properties of space-time at very short distances. In particular, near the Planck length, around 10<sup>-35</sup> m, empty space may behave as a crystal, si...Quantum or torsion gravity models predict unusual properties of space-time at very short distances. In particular, near the Planck length, around 10<sup>-35</sup> m, empty space may behave as a crystal, singly or doubly refractive. This hypothesis, however, remains uncheckable for any direct measurement since the smallest distance accessible in experiment is about 10<sup>-19</sup> m at the LHC. Here we propose a laboratory test to measure space birefringence or refractivity induced by gravity. A sensitivity 10<sup>-31</sup> m for doubly and 10<sup>-28</sup> m for singly refractive vacuum could be reached with PETRA 6 GeV beam exploring UV laser Compton scattering.展开更多
文摘Quantum or torsion gravity models predict unusual properties of space-time at very short distances. In particular, near the Planck length, around 10<sup>-35</sup> m, empty space may behave as a crystal, singly or doubly refractive. This hypothesis, however, remains uncheckable for any direct measurement since the smallest distance accessible in experiment is about 10<sup>-19</sup> m at the LHC. Here we propose a laboratory test to measure space birefringence or refractivity induced by gravity. A sensitivity 10<sup>-31</sup> m for doubly and 10<sup>-28</sup> m for singly refractive vacuum could be reached with PETRA 6 GeV beam exploring UV laser Compton scattering.
