It was during his time at a Jesuit secondary school where he first felt the urge to become a priest, but also a scientist.
Post the war, Georges Lemaitre completed his education from various colleges and in 1925 he returned to Belgium and became a part-time lecturer (and later a full-time professor) at the Catholic University of Leuven, where he remained for the rest of his career. After the war ended, he went on to study at Cambridge, Harvard, and MIT.
In 1931, Lemaitre realised that if the universe is ever expanding, it must have originated from a small, concentrated state.
Lemaitre's thesis was based on, and borrowed from Einstein's Theory of General Relativity but when he shared his ideas with the latter, Einstein was least impressed. However, two years later, Einstein accepted the calculations to be correct.
At a seminar in California, Einstein reportedly said of Lemaitre's theory: 'This is the most attractive and satisfactory explanation of creation to which I have ever listened'. He called it as the "hypothesis of the primeval atom" or the "Cosmic Egg".
Lemaitre's 1927 paper theorising that the universe was expanding was soon substantiated by Edwin Hubble's observations, which were published in 1929. In fact, Lemaitre had, in his paper, successfully calculated the numerical value that describes the rate of expansion of universe, what we now refer to as the Hubble constant.
This is a scientific theory about how the universe started, which went on to make the stars and galaxies of today.
He died on June 20, 1966.
This provided further evidence to his theory about the birth of the universe.
Lemaitre's work was widely recognised around the world, and are hugely influential until this day.