The Big Bang (1927-1964)

Georges Lemaitre's 1927 proposal that the universe was expanding from an initial singularity — confirmed by Hubble's 1929 observations of receding galaxies and the 1964 discovery of cosmic microwave background radiation by Penzias and Wilson — gave humanity its first scientific account of the origin of the universe. The Big Bang is now supported by convergent evidence from four independent observational methods and is the foundation of modern cosmology.