Is there any evidence for extra-dimensions or quantum gravity effects from the delayed MeV–GeV photons in GRB 940217?

The discovery of X-ray afterglows of GRBs, and the identification of host galaxies of GRBs, confirm the cosmological origin of GRBs. However, the discovery of the delayed MeV–GeV photons in GRB940217 imposes serious challenges for the standard emission model of GRB. Although the delayed MeV–GeV photons might be explained by some radiation emission mechanisms, the mystery of detecting an 18 GeV photon still remains unsolved. We suggest that the detection of the 18 GeV photon ∼4500 s after the keV/MeV burst in GRB 940217 provides a strong evidence for the existence of extra-dimensions and/or quantum gravity effects. The delay scale of the 18 GeV photon leads to an estimation of the fundamental energy scale, associated with the linear energy dependence of the speed of light, of the order of 2.1 × 1015 GeV, which is consistent with the results obtained by another independent analysis on the data of OSSE and BATSE.