Energydominated

Energydominated refers to a phase in the early universe where the energy density of radiation significantly exceeded that of matter. This epoch occurred shortly after the Big Bang, following the Planck epoch and the GUT epoch. During this period, the universe was expanding and cooling, and the dominant component of its energy density was electromagnetic radiation, including photons and neutrinos. As the universe continued to expand, the energy density of matter and dark energy also played roles, but in the energy-dominated era, radiation was the primary driver of cosmic evolution.

The characteristics of the energy-dominated era are crucial for understanding the subsequent evolution of the universe. The immense energy density influenced the expansion rate and the formation of the first structures. As the universe cooled, the energy density of radiation decreased faster than that of matter due to their different dependencies on the expansion. Photons, for example, lose energy as their wavelength is stretched by the expansion. This gradual shift in dominance from radiation to matter was a pivotal transition.

The end of the energy-dominated era and the beginning of the matter-dominated era is a significant milestone. This transition is estimated to have occurred around 50,000 years after the Big Bang, when the energy density of matter became equal to that of radiation. Following this, the matter-dominated era continued until the recent onset of the dark energy-dominated era. Understanding these cosmic epochs is fundamental to modern cosmology and the study of the universe's origins and evolution.