Georges Lemaitre, a Belgian physicist, and Catholic priest, first presented the Big Bang idea in 1927. Lemaitre’s idea was based on Albert Einstein’s general relativity theory, which proposed that the universe expanded from a condition of great density and temperature. He called this early condition the “primeval atom” or the “Cosmic Egg.”
Lemaitre’s views received widespread attention and were later explored and backed by other scientists, including Edwin Hubble, who gave observable evidence for the universe’s expansion. The Big Bang idea eventually became the most widely accepted cosmological model for the universe’s origins and evolution.