His theory was observationally confirmed soon afterwards by Edwin Hubble in what is now known as Hubble’s Law.
Lemaître is also credited with proposing what has now become known as the Big Bang theory – which says that the observable universe began with an explosion of a single particle.
The theory, which is now widely accepted, first appeared in 1931 in one of Lemaître’s academic papers and was a significant break from the orthodoxy of the time.
Born on 17 July 1894 in Belgium, he initially began studying civil engineering. His academic pursuits were however put on hold while he served in the Belgian army for the duration of the First World War.
After the war, he studied physics and mathematics and was also ordained as a priest.
In 1923 he became a graduate student at the University of Cambridge before going on to study at Harvard and Massachusetts Institute of Technology (MIT).
In 1925 he returned to Belgium, where he became a part-time lecturer at the Catholic University of Leuven. Two years later, he published his groundbreaking idea of an expanding universe.
His initial idea was not related specifically to the Big Bang, but his later research focused on the concept of the universe starting from a single atom.
In 1933 at the California Institute of Technology, some of the greatest scientists of the time from around the world gathered to hear a series of lectures.
After Lemaître delivered his lecture and theory, Albert Einstein stood up and said: “This is the most beautiful and satisfactory explanation of creation to which I ever listened.”
He was elected a member of the Royal Academy of Sciences and Arts of Belgium and the Pontifical Academy of Sciences.
In 1951, Pope Pius XII claimed that Lemaître’s theory provided a scientific validation for Catholicism – a claim that Lemaître resented, as he stated his theory was neutral.
He died in 1966, shortly after he discovered the existence of cosmic microwave background radiation, which added weight to his theory on the birth of the universe.
* This article was automatically syndicated and expanded from The Independent.