Gamma-Ray Bursts (GRBS) are the brightest explosions observed. After
a serendipitous discovery and forty years of search we begin to
understand their origin (type Ic supernovae for long bursts and
neutron star mergers for short ones) and how they operate. While the
research on the nature of GRBs still goes on we turn to application
of GRBs to study other phenomena. GRBs have an enormous potential to
explore new regimes of ultra-relativistic flows and of very high
magnetic fields. A lot have been said about the potential usage of
GRBs to determine the conditions at the early universe. Here we
discuss an application of GRBs that involve new physics – namely,
using the arrival times of photons and neutrinos at different
energies to set limits on Lorentz invariance violation that could
arise from quantum gravity effects.