Concept
Big Bang Nucleosynthesis
The first few minutes that forged hydrogen and helium.
Nuclear reactions in the first ~20 minutes after the Big Bang produced about 75% hydrogen, 25% helium, plus trace deuterium and lithium.
Overview
Nuclear reactions in the first ~20 minutes after the Big Bang produced about 75% hydrogen, 25% helium, plus trace deuterium and lithium.
See also
Reionization Epoch
When the first stars and galaxies relit the universe.
Warm Neutral Medium
Diffuse warm hydrogen filling much of the galaxy.
Cold Neutral Medium
Cool, denser neutral hydrogen clouds.
The Big Bang
How everything began, 13.8 billion years ago.
Black Holes
Regions where gravity stops light itself.
Dark Matter
The invisible mass holding galaxies together.