Exotic Acceleration Processes and Fundamental Physics
  Gamma-ray bursts and ultra-high-energy cosmic rays provide an important testing ground for fundamental physics. A simple-minded analysis of some gamma-ray bursts would lead to a huge estimate of the overall energy emitted, and this represents a potential challenge for modelling the bursts. Some cosmic rays have been observed with extremely high energies, and it is not easy to envision mechanisms for the acceleration of particles to such high energies. Surprisingly some other aspects of the analysis of gamma-ray bursts and ultra-high-energy cosmic rays, even before reaching a full understanding of the mechanisms that generate them, can already be used to explore new ideas in fundamental physics, particularly for what concerns the structure of spacetime at short (Planckian) distance scales. 
Giovanni Amelino-Camelia