Protons and neutrons combined to form hydrogen, helium, and traces of lithium during the first three minutes. This process, called Big Bang nucleosynthesis, determined the primordial chemical composition. Heavier elements had to wait for stars to form. Ratios of these elements in ancient stars confirm cosmological models. This early chemistry set the stage for future stars, planets, and life. It’s remarkable that the universe’s first chemistry happened before any stars existed.
It matters because it explains the abundance of light elements we observe today.
It also provides a crucial test for Big Bang theory predictions.
The universe’s first chemical reactions occurred long before stars existed.
National Aeronautics and Space Administration [nasa.gov]