Georges Lemaître

• 1. Introduction

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  Georges Henri Joseph Édouard Lemaître was a Belgian Catholic priest who proposed that the entire universe began as a single quantum he called the "primeval atom" - what the world would eventually come to know as the Big Bang. Born on the 17th of July 1894 in Charleroi, Belgium, he managed something rare in the history of thought: he was deeply devout and deeply scientific, and he refused to let those two things collapse into each other. How does a man trained for the priesthood end up rewriting humanity's understanding of cosmic origins? How did his central insight get buried in an obscure Belgian journal for years, only to be rediscovered by the very community that had ignored it? And what did Albert Einstein say to him in California in 1933 that was later disputed by historians? Those are the questions this documentary follows.

• 2. A Glass Factory and a War

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  Joseph Lemaître, Georges's father, owned a glassworks factory in Charleroi and was prosperous enough to send his eldest son to a Jesuit grammar school, the Collège du Sacré-Cœur. In 1910 a fire destroyed the factory, and the family relocated to Brussels, where Joseph found a new position managing the French bank Société Générale. Georges continued his education at another Jesuit school, St. Michael's College, and though he had already expressed interest in a religious life, his father persuaded him to study engineering first.

  In 1914, after one year of engineering studies at the Catholic University of Louvain, Lemaître interrupted everything to volunteer for the Belgian army. He fought at the Battle of the Yser, where Belgian forces halted the German advance. When he transferred from infantry to artillery, he was sent on a ballistics course - and promptly damaged his promotion prospects by pointing out a mathematical error in the official artillery manual. The instructors marked him down for insubordination. He finished the war not as an officer but as one of only five rank-and-file soldiers to receive the Belgian War Cross with bronze palm directly from King Albert I.

  During a wartime leave, Lemaître visited the French Catholic writer Léon Bloy in Bourg-la-Reine, near Paris, at a house that had belonged to the late writer Charles Péguy. He brought Bloy an essay he had written trying to reconcile the Genesis creation narrative with modern science. Bloy was unimpressed and told Lemaître to study the Church Fathers more carefully. That encounter may have planted the seed of Lemaître's lifelong resistance to blending theology with scientific argument.

• 3. Priest and Physicist

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  Between 1920 and 1923, Lemaître studied at the Maison Saint-Rombaut, the seminary of the Archdiocese of Mechelen reserved for older candidates for the priesthood. It was during his spare time there that he taught himself the general theory of relativity. His superior, Cardinal Désiré-Joseph Mercier, was unusual among senior Catholic clergy in actively supporting scientific work, and he arranged funding for Lemaître to travel abroad. On the 22nd of September 1923, Cardinal Mercier ordained Lemaître as a priest.

  Only ten days after his ordination, Lemaître left Belgium for St Edmund's House in Cambridge, a community of Catholic priests pursuing degrees at the University of Cambridge. There he worked with Arthur Eddington, the eminent astrophysicist who introduced him to modern cosmology, stellar astronomy, and numerical analysis. The following year he moved to the Harvard College Observatory in Cambridge, Massachusetts, working with Harlow Shapley on what were then called "spiral nebulae" - objects now identified as spiral galaxies. He simultaneously enrolled in the doctoral program at MIT, with Belgian engineer Paul Heymans as his official advisor.

  At the seminary, Lemaître had also joined the Fraternité sacerdotale des Amis de Jésus, a priestly fraternity created by Cardinal Mercier. He took vows of chastity, poverty, and obedience, as well as a special votum immolationis - a vow of complete submission to Christ. He kept his membership in the group largely private, but regularly made silent retreats at a house called Regina Pacis in Schilde, near Antwerp, and translated the mystical works of John of Ruusbroec.

• 4. The Ignored Paper

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  In 1927, Lemaître published a report in the Annales de la Société Scientifique de Bruxelles arguing that Albert Einstein's equations of general relativity implied that the universe is not static - it is expanding. He connected this to a proportional relationship between the recessional velocity of galaxies and their distance from Earth, independently of earlier work by Alexander Friedmann. The paper also contained his own estimate of what would later be called the Hubble constant.

  Almost no one read it. The Annales de la Société Scientifique de Bruxelles had almost no readership outside Belgium. Worse, when Lemaître met Einstein at a Solvay Conference in Brussels that same year and presented his findings, Einstein told him: "vos calculs sont corrects, mais votre physique est abominable" - "your calculations are correct, but your physics is abominable."

  In 1929, the American astronomer Edwin Hubble published findings in the Proceedings of the National Academy of Sciences showing, on better data, that galaxies recede at velocities proportional to their distance. Hubble himself did not frame this in terms of an expanding universe, but his paper attracted enormous attention and convinced many experts - including Einstein - that the universe is not static. The relationship was thereafter called Hubble's law, with Lemaître's prior work largely overlooked.

  In 1931, an English translation of Lemaître's 1927 paper appeared in the Monthly Notices of the Royal Astronomical Society. Eddington described it as a "brilliant solution" to the outstanding problems of cosmology. The translation, however, left out Lemaître's estimate of the Hubble constant. For years the reason was unclear. In 2011, the researcher Mario Livio established that Lemaître himself had removed those paragraphs when preparing the translation, choosing instead to cite Hubble's stronger 1929 results. In 2018, the International Astronomical Union voted 78% in favor of recommending that the law be called the Hubble-Lemaître law.

• 5. The Primeval Atom

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  In March 1931, Lemaître published a brief report in Nature proposing that the universe had expanded from a single initial quantum - a "primeval atom". Later that year, on the 29th of September 1931, he presented this idea at a public colloquium in London marking the centenary of the British Association for the Advancement of Science. The colloquium's subject was "The Evolution of the Universe".

  Lemaître's theory reached a general audience in the December 1932 issue of Popular Science, through a piece written by astronomer Donald Howard Menzel of Harvard University. In 1933-1934, Lemaître was a guest professor at the Catholic University of America in Washington, D.C., and presented his work on the expanding universe before the US National Academy of Sciences. Newspapers around the world described him as the leader of a new physical cosmology.

  Lemaître and Einstein met four times in total: in Brussels in 1927, in Belgium in 1932, in California in January 1933, and at Princeton in 1935. At the California Institute of Technology in 1933, after Lemaître presented his theory, Einstein stood and applauded. He is reported to have said, "This is the most beautiful and satisfactory explanation of creation to which I have ever listened." Historians have since noted disagreement over newspaper accounts of that event: it is possible that Einstein was responding specifically to Lemaître's proposal that cosmic rays could be fossils of the primordial decay, not to the primeval atom theory as a whole.

  In 1946, Lemaître published L'Hypothèse de l'Atome Primitif, which was translated into Spanish that year and into English in 1950. The astronomer Fred Hoyle introduced the term "Big Bang" in a 1949 BBC radio broadcast to describe Lemaître's type of theory - and Hoyle remained an opponent of that framework for the rest of his life, advocating instead for a steady-state model of an eternal universe.

• 6. Faith Without Concordism

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  In 1933, Lemaître told a journalist in terms that appeared in the New York Times: "There is no conflict between religion and science to reconcile." That sentence was the public face of a position he had worked out carefully over many years. As a student he had tried to prove that Genesis was compatible with physics. The meeting with Léon Bloy, and later conversations with Einstein, pushed him away from that approach.

  His position, once fixed, was principled and specific. He argued: "Should a priest reject relativity because it contains no authoritative exposition on the doctrine of the Trinity? Once you realize that the Bible does not purport to be a textbook of science, the old controversy between religion and science vanishes." He was also worried in the opposite direction: he feared that mixing cosmology with religious argument would undermine scientific credibility and misrepresent the faith at the same time.

  In 1951, Pope Pius XII addressed the Pontifical Academy of Sciences and drew a direct parallel between the Big Bang and the Christian doctrine of creatio ex nihilo, describing the new cosmology as "a witness to that primordial Fiat Lux." Lemaître was reportedly horrified. He worked through Father Daniel O'Connell, the director of the Vatican Observatory, to persuade the Pope not to make further public statements linking physical cosmology to religious doctrine. He succeeded.

  The Nobel laureate Paul Dirac recalled telling Lemaître that cosmology seemed to him the branch of science lying closest to religion. Lemaître, after thinking it over, disagreed. He suggested psychology instead.

• 7. Computers, Cosmic Rays, and Quaternions

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  With Manuel Sandoval Vallarta, whom he had first met at MIT, Lemaître demonstrated in the 1930s that cosmic rays vary in intensity with latitude because they carry electric charge and are deflected by the Earth's magnetic field. Their calculations used MIT's new differential analyzer computer, developed by Vannevar Bush. That finding directly contradicted the view of Nobel laureate Robert Millikan, who had argued that cosmic rays were composed of high-energy photons.

  Lemaître became genuinely absorbed by computation as a tool in physics. In the 1930s he used a mechanical Mercedes-Euklid calculator, then introduced the Burroughs E101 electromechanical computer to Louvain in the late 1950s. In his later years he collaborated with his nephew Gilbert Lemaître on a new programming language called "Velocode", which was a precursor of BASIC.

  In 1933, Lemaître found a significant inhomogeneous solution to Einstein's field equations describing a spherical dust cloud, now called the Lemaître-Tolman metric. He also worked on the three-body problem, introducing a method of regularization to handle singularities from two-body collisions. In the 1950s he worked out an early version of the fast Fourier transform, a technique later developed independently by James Cooley and John Tukey.

  In 1948, he published a mathematical essay on quaternions and elliptic space, working from foundations introduced by William Kingdon Clifford in 1873 and developing the theory in the spirit of the Erlangen program.

• 8. Final Years and Legacy

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  In December 1964, Lemaître suffered a heart attack. His health made it impossible for him to travel to Rome, so when Pope Paul VI asked him to serve on the Pontifical Commission on Birth Control during the Second Vatican Council, he declined. He told a Dominican colleague, Père Henri de Riedmatten, that he thought it was dangerous for a mathematician to venture outside his area of expertise.

  In 1960, Pope John XXIII had named him a domestic prelate with the title of Monsignor, and that same year Lemaître was appointed president of the Pontifical Academy of Sciences, succeeding the physician and Capuchin friar Agostino Gemelli. He held that position until his death. He also received the first Eddington Medal from the Royal Astronomical Society in 1953, specifically cited for his work on the expansion of the universe. On the 17th of March 1934, King Leopold III had presented him with the Francqui Prize, Belgium's highest scientific distinction; his nominators had included Albert Einstein and Charles de la Vallée-Poussin.

  Lemaître died on the 20th of June 1966, shortly after learning that his assistant Odon Godart had told him of the recent detection of the cosmic microwave background by radio astronomers Arno Penzias and Robert Wilson. In 1948, Ralph Alpher, Robert Herman, and George Gamow had predicted exactly such a radiation signature from the Big Bang model. Its discovery in the mid-1960s persuaded most of the scientific community that Lemaître had been right. In December 2022, VRT recovered a lost 20-minute interview with Lemaître recorded in 1964, which cosmologist Thomas Hertog described as "a gem".