This movie simulates the formation of galaxies, illustrating how ultraviolet (UV) radiation from other galaxies and from quasars suppresses the formation of stars inside small galaxies near to large galaxies similar to the Milky Way and Andromeda.The left panel shows a simulation that includes how diffuse UV radiation leads to fewer smaller galaxies forming.For comparison, the right panel shows what would happen in the absence of such radiation, with more small galaxies forming.
