Matter-Dominated Era

Matter-Dominated Era

The Matter-Dominated Era was the epoch in the evolution of the Universe that began after the Radiation-Dominated Era ended, when the Universe was about 380,000 years old. Although it was often said that we still live in the Matter-Dominated Era, it is more correct to say that when the Universe was about 5 billion years old, this era ended and was replaced by the Dark-Energy-Dominated Era. This change of the perspective occurred when the cosmological constant or dark energy was first observed in the late 1990s.

In the Matter-Dominated Era, the energy density of matter exceeds the energy density of radiation in the universe (and it should exceed the vacuum energy density i.e. dark energy, too). [Zelik, M and Gregory, S: "Introductory Astronomy & Astrophysics", page 497. Thompson Learning, Inc. 1998]

For a matter dominated universe the evolution of the scale factor in the Friedmann-Lemaitre-Robertson-Walker metric is easily obtained solving the Friedmann equations:

:a(t)propto t^{2/3}

References


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