The Dark Era

The Dark Era refers to a period in the early universe, roughly 380,000 years after the Big Bang, when the universe was filled with hot, dense plasma of particles and light couldn't travel freely. During this time, atoms hadn't formed yet, and the universe was opaque. It was called "dark" because there were no stars or light sources; the cosmos was a uniform, dark fog. This era ended when the universe cooled enough for atoms to form, allowing light to travel freely, leading to the transparent universe we observe today as the Cosmic Microwave Background.