One key question that has puzzled astronomers for decades is: When did the first stars and galaxies form after the Big Bang occurred? The answer — very quickly! Astronomers Rennan Barkana of Tel Aviv University and Avi Loeb of the Harvard-Smithsonian Center for Astrophysics found the first direct evidence that galaxies as large as the Milky Way already had formed when the Universe was less than a billion years old. “In some ways, it’s surprising that such large galaxies formed so quickly. Most galaxies in the early Universe were only one-hundredth that size,” said Loeb. “But our model, combined with observations by other researchers, provides clear evidence that massive galaxies existed within a relatively short time after the Big Bang.” Intriguingly, the large galaxies discovered by Barkana and Loeb are still around today. Over billions of years, they continued to consume smaller galaxies, like a cosmic software corporation absorbing many smaller companies. These galactic cannibals have grown from the seeds that existed in a billion-year-old Universe to become monstrous giant elliptical galaxies, resting in the centers of galaxy clusters. The research was reported in the Jan. 23, 2003 issue of the journal Nature.