Georges Lemaître

Georges Henri Joseph Édouard Lemaître was a Belgian Catholic prelate, mathematician, and theoretical physicist who first conceived the modern concept of the origin of the cosmos. After serving as an artillery officer in World War I where he was awarded the Croix de Guerre, Lemaître was ordained a priest in 1923 while simultaneously studying astrophysics at Cambridge under Arthur Eddington and at MIT and Harvard.

In 1927, two years before Edwin Hubble's famous paper, Lemaître solved Einstein's general relativity field equations to propose that the universe is expanding, and derived what is now known as the Hubble-Lemaître law. In 1931, taking his concept to its boldest logical conclusion, he proposed his famous 'hypothesis of the primeval atom' (or 'Cosmic Egg')—postulating that the cosmos originated from a single infinitely dense quantum singularity on 'a day without yesterday'. Initially dismissed by Einstein, his model was verified by the 1964 discovery of the cosmic microwave background, which Lemaître learned of on his deathbed.