Lemaitre, Abbe Georges Edouard (1894-1966), a Belgian astrophysicist. In 1927 he originated the "big bang" theory to explain the creation of the universe. His theory suggests that billions of years ago the universe was extremely small and dense (smaller even than an atom) but then exploded (the "big bang") and has been expanding ever since. Lemaitre's theory went largely unnoticed until, in the late 1940's, George Gamow elaborated on and popularized it.
Lemaitre was ordained a priest in 1922, but went on to study astrophysics, obtaining his doctorate from the Massachusetts Institute of Technology in 1927. He then taught at the University of Louvain.