Georges Lemaître

Georges Henri Joseph Édouard Lemaître was a Belgian Catholic priest, theoretical physicist, and mathematician who made major contributions to cosmology and astrophysics. He was the first to argue that the recession of galaxies is evidence of an expanding universe and to connect the observational Hubble–Lemaître law with the solution to the Einstein field equations in the general theory of relativity for a homogenous and isotropic universe. That work led Lemaître to propose what he called the "hypothesis of the primeval atom", now regarded as the first formulation of the Big Bang theory of the origin of the universe.