Who created the 'Big Bang Theory of Creation'?

The man credited with creating the 'Big Bang Theory of Creation' is George Lemaitre. Georges Henri Joseph Édouard Lemaître, aka George Lemaitre, was a Jesuit trained Belgian Catholic priest. He was also a mathematician, astronomer, and professor at the Catholic University of Louvain. He had the first definitive and solid idea of an expanding universe and what was to become known as the 'Big Bang Theory' of the origin of the universe, which Lemaître himself called his “hypothesis of the primeval atom” or the “Cosmic Egg”.

It was Lemaitre who directly pointed out, with the 'Big Bang Theory', that the universe emerged from an extremely dense and hot state (singularity). The universe must have started as a single particle at a definite point in time and its expansion has been going on since the beginning.

George Lemaitre was born in July 1894 in Charleroi, Belgium. At the age of 17, he began studying civil engineering at the Catholic University of Leuven (Louvain). In 1914, he joined the Belgian army for the duration of World War I.

After the war, Lemaître studied physics and mathematics and prepared for the priesthood. He got a doctorate (1920) and was ordained a priest (1923). He then became a graduate student in astronomy (the University of Cambridge in England). He learned about modern cosmology. In 1927, he discovered a family of solutions to Einstein's field equations of relativity that described not a static universe, but an expanding universe. He died in June 1966.