Physicists used to believe that the universe existed forever, there was no beginning, and there would be no end. The universe seemed as constant, as dependable as the night sky that never failed to show up, night after night. Of course, this view conflicted with religions that had stories on the creation of the universe. So it makes sense that the Big Bang Theory--the idea that our universe had a beginning, because it's expanding--was first developed by a priest.
Georges Lemaître, a Belgian Roman Catholic priest, astronomer, and professor of physics at the Université catholique de Louvain, was the first to propose that the universe was expanding. His work paved the way for the Big Bang Theory.
But is physics taking us back to the theory that the universe is in fact eternal? MinutePhysics explores the science and some of the religion behind the Big Bang Theory: