density parameter

density parameter

Symbol: ω. A key parameter in determining the fate of the Universe. It is defined as the ratio of the actual density of matter in the Universe to the critical density, where the critical density is the density of matter above which an expanding Universe will eventually recollapse. It is currently thought that the value of ω is about 0.3. Before 1980 it was one of the mysteries of cosmology as to why the value of ω is fairly close to 1. The theory of inflation provides an explanation of why this is the case.