Photon Epoch
Radiation dominates the universe. Light and matter remain tightly coupled in a hot, glowing fog.
Radiation now dominates the universe. Photons scatter constantly off charged particles, preventing light from travelling freely. The universe is opaque, filled with a hot, glowing plasma.
During this epoch, protons and neutrons fuse into the first atomic nuclei in a process known as primordial nucleosynthesis. Hydrogen and helium form in abundance, with trace amounts of lithium.
Light and matter remain tightly coupled. The photon epoch ends only when the universe cools enough for electrons to bind to nuclei, allowing photons to finally move unimpeded.
