Inorganic geochemical record Fossil record. Began in 1920 s when Hubble discovered there are galaxies outside our Milky Way. Our Milky Way, an ordinary galaxy, contains almost 100 billion stars. New estimate is 50 billion galaxies in the universe, up from 10 billion. The Universe is Expanding Hubble discovered that all galaxies are moving away from us.
Red light has a longer wavelength than blue.
The wavelengths of the lines are precise. Compare sound waves from a passing car as heard by a roadside listener. A Brief History of Time by Stephen Hawkings describes subatomic events milliseconds after the Big Bang. Based on life cycles of stars. Half-life is constant.