When electrons combined with nuclei to form neutral atoms.
The last scattering surface is the sphere of light emitted about 380,000 years after the Big Bang, when the universe cooled enough for electrons and protons to form neutral hydrogen. This cosmic relic, observed as the cosmic microwave background, provides a snapshot of the infant universe and anchors our understanding of cosmic evolution from the Planck epoch to the present day.
Recombination marks the moment about 378,000 years after the Big Bang when free electrons and protons combined to form neutral hydrogen, allowing photons to travel freely and making the universe transparent. This epoch gave birth to the cosmic microwave background and set the stage for the formation of stars and galaxies.
A comprehensive guide to the cosmic dark ages, the period when the universe was shrouded in neutral hydrogen, and how the first stars and galaxies emerged to end the darkness. This article covers the full cosmic timeline, key missions, and the evidence that shapes our understanding of this pivotal era.
Before recombination, the universe was an opaque plasma of free electrons and photons. When electrons and protons combined to form neutral hydrogen, light finally decoupled, creating the cosmic microwave background. This article explains the physics behind this cosmic milestone and why no telescope can see earlier with light.
Approximately 380,000 years after the Big Bang, the universe cooled enough for electrons and protons to combine into neutral hydrogen, releasing the cosmic microwave background. This pivotal moment, called recombination, marked the universe’s transition from an opaque plasma to a transparent state, setting the stage for the first stars and galaxies.
