ABSTRACT
The Universe is made up of various kinds of things, including exotic particles such as neutrinos, radiation left over from the “big bang,” a cosmological constant, and ordinary matter. There is a large amount of structure at all scales in the Universe. This structure grows in size and in power from the galaxy scale to the supercluster scale. This entry discusses luminous matter, dark matter, and provides theories for the origin and evolution of the Universe, accounting for the structure that is seen in the cosmic microwave background, superclusters, clusters, groups, and galaxies.
