To cite this article: Simon A. Mitton, ‘Georges Lemaître and the foundations of Big Bang cosmology.’ The Antiquarian Astronomer 14 (June 2020), 2–20. Keywords. Georges Lemaître, Einstein universe, De Sitter universe, cosmological constant, Hubble law, expanding universe, dark energy, general relativity, science and religion Author: Simon A. Mitton,
[email protected]. St Edmund’s College, Cambridge CB3 0BN, United Kingdom Georges Lemaître and the foundations of Big Bang cosmology Simon A. Mitton Georges Lemaître was a remarkable contributor to the advancement of cosmol- ogy in the heady years following the two great revolutions in theoretical physics in the last century: general relativity and quantum mechanics. In the past two decades the impact of his key publications has advanced from very little to enor- mous. Among other landmark achievements, Lemaître was the first cosmologist to estimate the rate of expansion of the Universe, later known as the Hubble constant. In 2018 the International Astronomical Union renamed the Hubble law as the Hubble–Lemaître law in recognition of his foundational contribution to the theory of the expanding Universe. This biographical review examines: factors that influenced his approach to the philosophy of science, particularly cosmology; his engagement with the network of contemporary cosmologists; and the circumstances of his withdrawal from research in cosmology and the further promotion of ‘the fireworks universe’ after the early 1930s. 1. Recognition by the International 2. Early life and education Astronomical Union 2018 Georges Lemaître had a fascinating and varied life in Georges Henri Joseph Édouard Lemaître (1894–1966) science. As a Catholic priest he made an intriguing aca- died three days after learning from his successor at the demic, working in both heavenly theology and cosmical Catholic University of Louvain, the Belgian mathemati- theory.