**Georges Henri Joseph Édouard Lemaître** was a Belgian mathematician and astronomer who worked on the theory of an expanding universe.

- Another change in his life brought about by his wartime experiences came about when he enrolled at the Maison Saint Rombaut, a seminary of the Archdiocese of Malines, and was ordained in 1923, becoming Abbé Lemaître.
- Now, with the strong mathematical background obtained from his studies with de la Vallée Poussin, Lemaître turned towards mathematical astronomy and went to Cambridge in England where he studied with Eddington during the academic years 1923-24, then he went to the United States spending the next academic year at the Harvard College Observatory in Massachusetts.
- In this groundbreaking paper Lemaître derived what is now known as Hubble's Law relating the speed with which a galaxy is moving away to its distance.
- Einstein was at the conference and he spoke to Lemaître in Brussels telling him that the ideas in his 1927 paper had been presented by Friedmann in 1922, but he also said that although he thought Lemaître's solutions of the equations of general relativity were mathematically correct, they presented a solution which was not feasible physically.
- Einstein was not alone in finding Lemaître's ideas totally unacceptable; rather this was the opinion of almost all scientists.
- Lemaître then sent a copy of his 1927 paper to Eddington who immediately saw that it provided an explanation.
- Eddington arranged for an English translation of Lemaître's paper to be published in the Monthly Notices of the Royal Astronomical Society and indeed it appeared there in March 1931.
- There was still a part of Lemaître's theory that scientists, including Eddington, found impossible to accept, namely the implication that the universe had a beginning at a finite time in the past.
- We leave it to the reader to ponder the thought that perhaps Lemaître's deep Christian beliefs made the thought that the world began at a finite time in the past (as the book of Genesis claims) more easily accepted.
- Lemaître responded to the objections against his theory in a paper published in Nature in May 1931.
- We should note that, although accepted by most scientists, Fred Hoyle did not accept this theory and the term 'big bang' was Hoyle's scornful description of Lemaître's theory in a 1950 radio broadcast.
- In 1933 Einstein and Lemaître gave a series of lectures in California.
- Lemaître published a more detailed version of his theory in L'univers en expansion Ⓣ(The expanding universe) in 1933.
- Of course, the fact that Lemaître was both a leading scientist and a Catholic Priest was part of the fascination that the popular press had.
- Lemaître had been appointed Professor at Louvain in 1927 and remained there for the rest of his career.
- Lemaître then applied these ideas to accelerate the orthodox process of iteration, taking the Picard iterative solution of first order differential equations as an example.
- Lemaître taught less through the 1950s but continued to publish on the same topics that had interested him in the 1940s.
- However, a new interest came into Lemaître's research related to the introduction of computers into mathematical research.
- Lemaître retired in 1964 when he was made professor emeritus.
- He joined the army and, to quote from the author's statement, "after 53 months of war ordeals and military camps, he lost interest in a professional career and decided to become a priest"; this ultimately resulted in a change from engineering to the mathematical sciences, particularly to general relativity, which marked a very notable turning point in Lemaître's life.
- The sequence of events narrated by the author shows, however, that time and again Lemaître was accused (especially by Einstein) of using scientific reasonings "to defend a (religious) dogma of the Church".
- Was Lemaître the scientist being guided by Lemaître the Catholic priest?

Born 17 July 1894, Charleroi, Belgium. Died 20 June 1966, Charleroi, Belgium.

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Astronomy, Origin Belgium

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive