Georges Lemaître

Georges Henri Joseph Édouard Lemaître (ləˈmɛtrə ; ʒɔʁʒ ləmɛːtʁ; 17 July 1894 – 20 June 1966) was a Belgian Catholic priest, theoretical physicist, mathematician, astronomer, and professor of physics at the Catholic University of Louvain. He was the first to theorize that the recession of nearby galaxies can be explained by an expanding universe, which was observationally confirmed soon afterwards by Edwin Hubble. He first derived "Hubble's law", now called the Hubble–Lemaître law by the IAU, and published the first estimation of the Hubble constant in 1927, two years before Hubble's article. Lemaître also proposed the "Big Bang theory" of the origin of the universe, calling it the "hypothesis of the primeval atom", and later calling it "the beginning of the world". Lemaître was born in Charleroi, Belgium, the eldest of four children. His father Joseph Lemaître was a prosperous industrial weaver and his mother was Marguerite, née Lannoy. After a classical education at a Jesuit secondary school, the Collège du Sacré-Cœur, in Charleroi, in Belgium, he began studying civil engineering at the Catholic University of Louvain at the age of 17. In 1914, he interrupted his studies to serve as an artillery officer in the Belgian army for the duration of World War I. At the end of hostilities, he received the Belgian War Cross with palms. After the war, he studied physics and mathematics, and began to prepare for the diocesan priesthood, not for the Jesuits. He obtained his doctorate in 1920 with a thesis entitled l'Approximation des fonctions de plusieurs variables réelles (Approximation of functions of several real variables), written under the direction of Charles de la Vallée-Poussin. He was ordained a priest on 22 September 1923 by Cardinal Désiré-Joseph Mercier. In 1923, he became a research associate in astronomy at the University of Cambridge, spending a year at St Edmund's House (now St Edmund's College, University of Cambridge). There he worked with Arthur Eddington, a devout Quaker and physicist who introduced him to modern cosmology, stellar astronomy, and numerical analysis.