In 1997 it was established that GRBs occupy the furthest reaches of the Universe and astronomers were immediately faced with the dilemma of how to produce so much energy in such a short period of time. They began with the assumption that GRBs emit their radiation isotropically (equally in all directions) much as a supernova does, but quickly decided that such massive energy production was physically unfeasable. If the radiation was emitted in this way, 3×1047 Joules of energy was required in less than a minute (the equivalent of 100,000 supernovae going off simultaneously) for the most energetic bursts!
Although this means that we are potentially seeing only a small fraction of the total number of GRBs (some estimates suggest that for every GRB we observe, there are 500 others we do not see), we no longer need to evoke exotic physics to account for their extreme energies. A hypernova explosion can account for the energy produced, and there is now convincing evidence that hypernovae are assocated with at least some GRBs.