Primordial nucleosynthesis occurred in the first three minutes, producing hydrogen, helium, and trace lithium. Conditions were hot and dense enough for nuclear fusion, but too brief for heavier elements. These light elements dominate the universe’s composition today. Measuring their abundance tests Big Bang predictions. This process also set the stage for star formation and chemical evolution. Every atom in our bodies started from these earliest moments.
The first elements matter because they shaped the chemical universe we see today.
It also helps astronomers verify Big Bang models through observed elemental ratios.
Hydrogen and helium were cooked up in the universe’s first minutes.
National Aeronautics and Space Administration [nasa.gov]