Quote:National Geographic:Giant Quasar a Head-ScratcherAstronomers have known for years that quasars can form immense clusters that stretch to more than 700 million light-years across, said Clowes. But the epic size of this group of 73 quasars, sitting about 9 billion light-years away, has left them scratching their heads.That's because current astrophysical models appear to show that the upper size limit for cosmic structures should be no more than 1.2 billion light-years."So this represents a challenge to our current understanding and now creates a mystery—rather than solves one," Clowes said. (Also see "Dark Galaxies Discovered—May Be Cosmic 'Missing Links.'")The titanic structure, known simply as the Large Quasar Group (LQG), also appears to break the rules of a widely accepted cosmological principle, which says that the universe would look pretty much uniform when observed at the largest scales."It could mean that our mathematical description of the universe has been oversimplified—and that would represent a serious difficulty and a serious increase in complexity," Clowes said.Decoding Early-Galaxy EvolutionSignificant not only for its record-breaking size, the massive structure could possibly shed light on the evolution of galaxies like our own Milky Way. Quasars, which pump out powerful jets of energy, are among the brightest and most energetic objects from when the universe was still young. They represent an early, but brief, stage in the evolution of most galaxies. (See "Earliest Known Galaxies Spied in Deep Hubble Picture.")One theory holds that this type of colossal collection of quasars may be precursors to galaxy superclusters in the modern universe—but the exact nature of their connection is still a mystery.The discovery, a prime target for computer modeling, also needs to be mapped out more thoroughly with telescopes, said Gerard Williger, an astronomer at the University of Louisville in Kentucky not connected with the study.