Georges Lemaître
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| Georges Lemaître | |
 Monsignor Georges Lemaître, priest and scientist
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| Born | July 17, 1894 |
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| Died | June 20, 1966 |
| Nationality | Belgian |
| Fields | astronomer |
| Institutions | Université catholique de Louvain |
| Known for | Big Bang |
| Religious stance | Roman Catholic |
Monsignor Georges Henri Joseph Éduard Lemaître (July 17, 1894 – June 20, 1966) was a Belgian Roman Catholic priest, honorary prelate, professor of physics and astronomer at the Université catholique de Louvain.
Fr. (later Msgr.) Lemaître proposed what became known as the Big Bang theory of the origin of the Universe, although he called it his 'hypothesis of the primeval atom'. [1][2][3]
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[edit] Work
He was a pioneer in applying Einstein's theory of general relativity to cosmology: suggesting a pre-cursor of Hubble's law in 1927, and then publishing his primeval atom theory in the pages of Nature in 1931. At the time Einstein believed in a static universe and had previously expressed his skepticism about Lemaître's original 1927 paper. A similar solution to Einstein's equations, suggesting a changing radius to the size of the universe, had been proposed in 1922 by Alexander Alexandrovich Friedman, as Einstein informed Lemaître when he approached him with the theory at the 1927 Solvay Conference (Friedman had also been criticized by Einstein), but it is Lemaître, with his proposed mechanism, that made the theory famous for several reasons according to historians. First, Friedman was a mathematician who was not working with astronomical data or concerned with the math as a description of physical reality. Secondly, Friedman died young and could not further work on his ideas. Thirdly, Lemaître worked with astronomers and made his theory in accord with observations and had consequences which could be tested. Fourth, Arthur Eddington made sure that Lemaître got a hearing in the scientific community.
Lemaître also proposed the theory at an opportune time since Edwin Hubble would soon release his velocity-distance relation that strongly supported an expanding universe and, consequently, the Big Bang theory. In fact, Lemaître derived what became known as Hubble's Law in his 1927 paper, two years before Hubble. However, since Lemaître spent his entire productive life in Europe rather than emigrating to America, the contributions of scientists such as Hubble or Einstein, who can be claimed to have a US connection, are often more well known in the US.
Both Friedman and Lemaître had found that the universe must be expanding. Lemaître went further than Friedman, since he concluded that an initial "creation-like" event must have occurred. This is the Big Bang theory as we know it today, and this is why he is credited with its discovery.
Einstein at first dismissed Friedman and then (privately) Lemaître out of hand, saying that not all mathematics leads to correct theories. After Hubble's discovery was published, Einstein quickly and publicly endorsed Lemaître's theory, helping both the theory and priest get fast recognition. [4]
In 1933 he found an important inhomogeneous solution of Einstein's field equations describing a spherical dust cloud, the Lemaitre-Tolman metric.
[edit] Biography
After studying humanities at a Jesuit school (Collège du Sacré-Coeur, Charleroi), Lemaître entered the civil engineering school of the Catholic University of Leuven at the age of seventeen. In 1914, at the beginning of World War I, he paused his studies to engage as a volunteer in the Belgian army. At the end of hostilities, he received the Military Cross with palms.
After the war, he undertook studies in physics and mathematics and began to prepare for priesthood. 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.
In 1923, he became a graduate student in astronomy at the University of Cambridge, spending one year at St Edmund's House (now St Edmund's College, Cambridge). He worked with the astronomer Arthur Eddington who initiated him into modern cosmology, stellar astronomy and numerical analysis. He spent the following year at Harvard College Observatory in Cambridge, Massachusetts with Harlow Shapley, who had just gained a name for his work on nebulae, and at the Massachusetts Institute of Technology, where he registered for the doctorate in sciences.
In 1925, on his return to Belgium, he became a part-time lecturer at the Catholic University of Leuven. He then began the report which would bring him international fame and which was published in 1927 in the Annales de la Société Scientifique de Bruxelles (Annals of the Scientific Society of Brussels), under the title Un Univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extragalactiques (A homogeneous Universe of constant mass and growing radius accounting for the radial velocity of extragalactic nebulae). In this report, he presented the new idea of an expanding Universe, but not yet of the primeval atom. Instead, the initial state was taken as Einstein's own finite-size static universe model. Unfortunately, the paper made little initial impact because this journal was not widely read by astronomers outside of Belgium.
At this time, Einstein, whilst approving of the mathematics of Lemaître's theory, refused to accept the idea of an expanding universe; Lemaître recalled him commenting "Vos calculs sont corrects, mais votre physique est abominable"[5]. The same year, Lemaître returned to MIT to present his doctoral thesis on The gravitational field in a fluid sphere of uniform invariant density according to the theory of relativity. He obtained a PhD and was then named ordinary Professor at the Catholic University of Leuven.
In 1930, Eddington published in the Monthly Notices of the Royal Astronomical Society a long commentary on Lemaître's 1927 article, in which he described it as a "brilliant solution" to the outstanding problems of cosmology. The original paper was published in an abbreviated English translation in 1931, along with a sequel by Lemaître responding to Eddington's comments. Lemaître was then invited to London in order to take part in a meeting of the British Association on the relation between the physical Universe and spirituality. It is there that he proposed an expanding Universe which started with an initial singularity, and the idea of the Primeval Atom which he developed in a report published in Nature. Fr. Lemaître himself also described his theory as "the Cosmic Egg exploding at the moment of the creation"; it became better known as the Big Bang theory, which was originally a critical comment by Fred Hoyle.
This proposal met skepticism from his fellow scientists at the time. Eddington found Lemaître's notion unpleasant. As for Einstein, he found it suspect, because, according to him, it was too strongly reminiscent of the Christian dogma of creation and was unjustifiable from a physical point of view. On the other hand, Einstein encouraged Lemaître to look into the possibility of non-isotropic expansion models, so it's clear he was not dismissive of the concept altogether. He also appreciated Lemaître's argument that a static-Einstein model of the universe could not be sustained indefinitely into the past.
In January 1933, Lemaître and Einstein, who had met on several occasions - in 1927 in Brussels, at the time of a Solvay Conference, in 1932 in Belgium, at the time of a cycle of conferences in Brussels and lastly in 1935 at Princeton - traveled together to California for a series of seminars. After the Belgian detailed his theory, Einstein stood up, applauded, and is supposed to have said, "This is the most beautiful and satisfactory explanation of creation to which I have ever listened". However there is disagreement over the reporting of this quote in the newspapers of the time and it may be that Einstein was not actually referring to the theory as a whole but to Lemaître's proposal that cosmic rays may in fact be the left over artifacts of the initial 'explosion'. Later research on cosmic rays by Robert Millikan would undercut this proposal, however.
In 1933, when he resumed his theory of the expanding Universe and published a more detailed version in the Annals of the Scientific Society of Brussels, Lemaître would achieve his greatest glory. Newspapers around the world called him a famous Belgian scientist and described him as the leader of the new cosmological physics.
On March 17, 1934, Lemaître received the Francqui Prize, the highest Belgian scientific distinction, from King Léopold III. His proposers were Albert Einstein, Charles de la Vallée-Poussin and Alexandre de Hemptinne. The members of the international jury were Eddington, Langevin and Théophile de Donder. Another distinction that the Belgian government reserves for exceptional scientists was allotted to him in 1950: the decennial prize for applied sciences for the period 1933-1942.
In 1936, he was elected member of the Pontifical Academy of Sciences. He took an active role there, became the president in March 1960 and remaining so until his death. At the outset of the Second Vatican Council, he was bemused to find himself appointed by the Pope to sit on a commission investigating the subject of birth control. However, as he could not travel to Rome because of his health (he had suffered a heart attack in December of 1964), he demurred, expressing his surprise that he was even chosen, at the time telling a Dominican colleague, P. Henri de Riedmatten, that he thought it was dangerous for a mathematician to venture outside of his specialty. [6]He was also named prelate (Monsignor) in 1960 by Pope John XXIII.
In 1941, he was elected member of the Royal Academy of Sciences and Arts of Belgium.
In 1946, he published his book on L'Hypothèse de l'Atome Primitif (The Primeval Atom Hypothesis), a book which would be translated into Spanish in the same year and into English in 1950.
In 1953 he was given the very first Eddington Medal award of the Royal Astronomical Society.
During the 1950s, he gradually gave up part of his teaching workload, ending it completely with his éméritat in 1964.
At the end of his life, he was devoted more and more to numerical calculation. He was in fact a remarkable algebraicist and arithmetical calculator. Since 1930, he used the most powerful calculating machines of the time like the Mercedes. In 1958, he introduced at the University a Burroughs E 101, the University's first electronic computer. Lemaître kept a strong interest in the development of computers and, even more, in the problems of language and programming. With age, this interest grew until it absorbed him almost completely.
He died on June 20, 1966 shortly after having learned of the discovery of cosmic microwave background radiation, proof of his intuitions about the birth of the Universe.
[edit] Namesakes
- The Lemaître crater, a lunar impact crater
- The Friedmann-Lemaître-Robertson-Walker metric
[edit] Trivia
- In 2005 Lemaître was voted to the 61st place of De Grootste Belg (Dutch for "The Greatest Belgian"), a Flemish television program on the VRT. In the same year he was voted to the 78th place by the audience of the Le plus grand belge (French for the "The Greatest Belgian"), a Walloon television show of the RTBF.
[edit] References
- ^ 'A Day Without Yesterday': Georges Lemaitre & the Big Bang
- ^ A Science Odyssey: People and Discoveries: Big bang theory is introduced
- ^ Lemaître - Big Bang
- ^ According to Simon Singh in his book Big Bang.
- ^ Deprit, A. (1984). "Monsignor Georges Lemaître". A. Barger (ed) The Big Bang and Georges Lemaître: 370, Reidel.
- ^ Lambert, Dominique. Un Atome d'Univers, Lessius, 2000, p. 302.
