在此引用其中一小段:
There are many astrophysical mechanisms that could produce a delay in the arrival time of high-energy photons or cosmic rays. The electron inverse scattering of the created electron-positron pairs of the cosmic microwave background photons will produce delayed MeV–GeV emission ……. It is important to note that all these delay mechanisms predict that the low-energy photons come late. However, in the models with extra dimensions the high-energy photon comes later.