It was at Leuven University in 1927, that the work for the “Big Bang” theory would begin. He gained acclaim upon publishing a report which stipulated a new idea of an expanding universe, derived from General Relativity; it provided the first observational estimation of the Hubble constant. In January 1933, Lema?tre and Einstein travelled together to attend a series of seminars in California. After Lema?tre detailed his theory, Einstein stood up, applauded, and is supposed to have said, “This is the most beautiful and satisfactory explanation of creation to which I have ever listened.”