Some 380,000 years after the Big Bang, when light could finally travel freely through space, the early universe was as smooth and featureless as a bowl of consommé. So how did the universe progress from such a dull and unpromising state to its current lumpy configuration full of galaxies and stars and planets?
A recent supercomputer simulation project called EAGLE (Evolution and Assembly of GaLaxies and their Environments) confirms and shows in great detail what has long been suspected. The tiny fluctuations in density in the early universe were magnified by gravity, with dark matter slowly congealing into denser clumps and filaments which then drew in hydrogen and helium gas where it formed into the first stars and galaxies.