 Quasars may have been an important energy source in this process, which marked the end of the cosmic Dark Ages, so observing a quasar from before the transition is of major interest to theoreticians.Because of their high ultraviolet luminosity, quasars also are some of the best sources for studying the reionization process.The discovery is also described as challenging theories of black hole formation, by having a supermassive black hole much larger than expected at such an early stage in the Universe's history, though this is not the first distant quasar to offer such a challenge.