Georges Lemaître (1894 - 1966) was a Belgian astrophysicist, mathematician, and Catholic priest who first argued that the universe is expanding and originated from a single dense point. [1] In 1927 he derived a relation between the distances of galaxies and their recession velocities, a result now honoured in the name of the Hubble-Lemaître law. [4] His 1931 hypothesis of the 'primeval atom' provided the conceptual starting point for what became known as the Big Bang theory. [3]
Early life and education
Georges Henri Joseph Édouard Lemaître was born on 17 July 1894 in Charleroi, Belgium. [1] He began studying civil engineering at the Catholic University of Leuven, but his education was interrupted by the First World War, during which he served as an artillery officer and was decorated for his conduct. [1] After the war he turned to mathematics and physics, earned a doctorate at Leuven, and was ordained a Catholic priest in 1923. He then continued his training abroad, studying under Arthur Eddington at the University of Cambridge and later at the Massachusetts Institute of Technology, where he engaged with the emerging observational astronomy of the day. [1]
The expanding universe
In 1927 Lemaître published a paper proposing that the universe is expanding, deriving a linear relation between the recession velocities of galaxies and their distances. [1] His work anticipated by two years the observational relation announced by Edwin Hubble in 1929. The connection was long credited to Hubble alone, but in 2018 the International Astronomical Union recommended the name Hubble-Lemaître law in recognition of Lemaître's priority. [4] Because his original paper appeared in a Belgian journal with limited circulation, its significance went largely unnoticed until an English translation was published in 1931. [1]
The primeval atom
In 1931 Lemaître advanced the idea that the expansion of the universe could be traced back to an initial state of extreme density, which he called the 'primeval atom' or 'cosmic egg'. [3] This hypothesis proposed a definite beginning to the cosmos and supplied the conceptual foundation of what would become the Big Bang theory. [3] As both a priest and a scientist, Lemaître maintained that his cosmological model was a physical hypothesis to be judged on scientific grounds, distinct from any theological or metaphysical interpretation. [1]
Later life and honours
Lemaître spent most of his career as a professor at the Catholic University of Leuven. [1] He received numerous distinctions, including the Francqui Prize, the Eddington Medal, and the Prix Jules Janssen, and in 1936 he was elected to the Pontifical Academy of Sciences, of which he later became president. [1] He died in Leuven on 20 June 1966, shortly after learning of the discovery of the cosmic microwave background radiation, which offered strong observational support for his account of an expanding universe with a hot, dense origin. [2]
Legacy
Lemaître is widely regarded as a founder of modern cosmology. [2] His recognition that the universe is expanding transformed the scientific understanding of cosmic history, and the renaming of the Hubble-Lemaître law formally acknowledged his contribution. His career is also frequently cited as an example of the compatibility of rigorous science with religious belief. [2]
