Lecture 35 - The Expanding Universe
"One could still imagine that God created the universe at the instant of the big bang, or even afterwards in just such a way as to make it look as though there had been a big bang, but it would be meaningless to suppose that it was created before the big bang. An expanding universe does not preclude a creator, but it does place limits on when he might have carried out his job!" ―- A Brief History of Time, Stephen Hawking"
In 1922, Alexander Friedmann proved that an isotropic, homogeneous universe cannot be static. By 1929, Hubble demonstrated that the clusters of galaxies are receding from us. Even prior to that, George Lemaitre had argued that if the universe is expanding, then it must have been very small and very hot in the beginning. In 1940, George Gamow conjectured that the elements may have been synthesized in the early universe. In this first of six lectures on Cosmology, I explain the expanding universe scenario, and the synthesis of light elements such as Deuterium and Helium. The synthesis of heavy elements in the stars, as well as exotic scenarios like the coalescence of two neutron stars, is also discussed.