Temperatures were hot enough for nuclear reactions, producing hydrogen, helium, and trace lithium. Heavier elements required stars to form later. This early fusion set the stage for all matter in the universe. Observations of primordial element ratios match theoretical predictions, confirming the Big Bang. Understanding nucleosynthesis helps trace cosmic history. It also constrains models of particle physics and cosmology.
Big Bang nucleosynthesis matters because it explains the universe’s chemical composition.
It also provides a benchmark for testing cosmological and particle physics theories.
The first atoms were forged within the first few minutes of cosmic time.
NASA Goddard Space Flight Center [nasa.gov]