From this point on, and for several billion years to come, the presence of dark matter accelerates the formation of structure in the universe. In the early universe, dark matter gradually gathers in huge filaments under the effects of gravity, collapsing faster than ordinary (baryonic) matter because its collapse is not slowed by radiation pressure. This amplifies the tiny inhomogeneities (irregularities) in the density of the universe which was left by cosmic inflation. Over time, slightly denser regions become denser and slightly rarefied (emptier) regions become more rarefied. Ordinary matter eventually gathers together faster than it would otherwise do, because of the presence of these concentrations of dark matter.