Lemaître Proposes an Expanding Universe

In 1927, Georges Lemaitre, a Belgian Catholic priest and theoretical physicist who had recently completed his doctoral dissertation at the Massachusetts Institute of Technology, published a theoretical paper in the Annales de la Societe Scientifique de Bruxelles. Within its pages, Lemaitre demonstrated that the field equations of Albert Einstein's general theory of relativity allowed for a universe that was non-static and continually expanding. He paired this mathematical deduction with astronomical observations of distant extragalactic nebulae, pointing out an apparent proportional relationship between their distances from Earth and their radial velocities.

Lemaitre's innovative conclusion challenged the prevailing scientific consensus of the 1920s, which favored an eternal, static cosmos. When Lemaitre met Einstein in Brussels in 1927 to discuss his conclusions, Einstein resisted the dynamic model. Although Einstein acknowledged that Lemaitre's mathematical calculations were accurate, he dismissed the physical implications as unacceptable, maintaining his preference for a static universe maintained by a finely tuned cosmological constant.