Concept
Recombination Epoch
When the universe became transparent.
About 380,000 years after the Big Bang, protons and electrons combined into neutral hydrogen, releasing the cosmic microwave background.
Overview
About 380,000 years after the Big Bang, protons and electrons combined into neutral hydrogen, releasing the cosmic microwave background.
See also
Dark Energy
The mysterious force accelerating the universe.
Gravity
The force that shapes the universe.
Redshift & Hubble's Law
The fingerprint of an expanding universe.
Baryon Acoustic Oscillations
A standard ruler frozen into the early universe.
Reionization Epoch
When the first stars and galaxies relit the universe.
Cosmic Dark Ages
The long pre-starlight era of the universe.