An international team of researchers have developed a computer program that simulates the growth and expansion of the Universe after the Big Bang, including the formation of galaxies, clusters and quasars. The “Millennium Simulation” used 10 billion virtual particles of matter, and traced their movements in a 2 billion light-year cube of space as the Universe evolved. This simulated area contained 20 million virtual galaxies, and accounted for dark energy expanding the Universe, cold dark matter, and regular matter.