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Georges Lemaître
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Portrait of Lemaître
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| Born | 17 July 1894
Charleroi, Belgium
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| Died | 20 June 1966 (aged 71)
Leuven, Belgium
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| Nationality | Belgian |
| Alma mater | Catholic University of Louvain St Edmund's House, Cambridge Massachusetts Institute of Technology |
| Known for | Theory of the expansion of the universe Big Bang theory Lemaître coordinates |
| Awards | Francqui Prize (1934) Eddington Medal (1953) |
| Scientific career | |
| Fields | Cosmology Astrophysics Mathematics |
| Institutions | Catholic University of Leuven |
| Doctoral advisor | Charles Jean de la Vallée-Poussin (Leuven) Arthur Eddington (Cambridge) Harlow Shapley (MIT) |
| Doctoral students | Louis Philippe Bouckaert, Rene van der Borght |
| Signature | |
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Georges Henri Joseph Édouard Lemaître, RAS Associate; 17 July 1894 – 20 June 1966) was a Belgian Roman Catholic priest, mathematician, astronomer, and professor of physics at the Catholic University of Louvain. He proposed on theoretical grounds that the universe is expanding, which was observationally confirmed soon afterwards by Edwin Hubble. He was the first to derive what is now known as Hubble's law, or the Hubble-Lemaître law, and made the first estimation of what is now called the Hubble constant, which he published in 1927, two years before Hubble's article. Lemaître also proposed what became known as the "Big Bang theory" of the creation of the universe, originally calling it the "hypothesis of the primeval atom".
Early life
According to the Big Bang theory, the universe emerged from an extremely dense and hot state (singularity). Space itself has been expanding ever since, carrying galaxies
with it, like raisins in a rising loaf of bread. The graphic scheme
above is an artist's conception illustrating the expansion of a portion
of a flat universe.
After a classical education at a Jesuit secondary school, the Collège du Sacré-Coeur, in Charleroi, Lemaître 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 the Cardinal Mercier.
In 1923, he became a research associate in astronomy at Cambridge UK, spending a year at St Edmund's House (now St Edmund's College, University of Cambridge). He worked with Arthur Eddington, who introduced him to modern cosmology, stellar astronomy, and numerical analysis. He spent the next year at Harvard College Observatory in Cambridge, Massachusetts, with Harlow Shapley, who had just gained renown for his work on nebulae, and at the Massachusetts Institute of Technology (MIT), where he registered for the doctoral program in sciences.
Career
On his return to Belgium in 1925, he became a part-time lecturer at the Catholic University of Louvain. He began the report which brought him international fame when it 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 his new idea that the universe is
expanding, which he derived from General Relativity; this later became
known as Hubble's law, but Lemaître provided the first observational estimation of the Hubble constant.
The initial state he proposed was taken to be Einstein's own model of a
finitely sized static universe. The paper had little impact because the
journal in which it was published was not widely read by astronomers
outside Belgium; Arthur Eddington reportedly helped translate the
article into English in 1931, but the part of it pertaining to the
estimation of the "Hubble constant" was not included in the translation
for reasons that remained unknown for a long time.
This issue was clarified in 2011 by Mario Livio; Lemaître omitted the
paragraphs when himself initially translating the paper for the Royal
Astronomical Society, in favor of reports of new work on the subject,
since by that time Hubble's calculations had already improved on his
earlier ones.
At this time, Einstein,
while not taking exception to the mathematics of Lemaître's theory,
refused to accept that the universe was expanding; Lemaître recalled his
commenting "Vos calculs sont corrects, mais votre physique est abominable"
("Your calculations are correct, but your physics is atrocious"). In
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. Upon obtaining his Ph.D., he was named ordinary professor at the Catholic University of Louvain.
In 1931, Arthur Eddington published in the Monthly Notices of the Royal Astronomical Society
a long commentary on Lemaître's 1927 article, in which he described the
latter as a "brilliant solution" to the outstanding problems of
cosmology.
The original paper was published in an abbreviated English translation
later on in 1931, along with a sequel by Lemaître responding to
Eddington's comments. Lemaître was then invited to London to participate in a meeting of the British Association
on the relation between the physical universe and spirituality. There
he proposed that the universe expanded from an initial point, which he
called the "Primeval Atom". He developed this idea in a report published
in Nature.
Lemaitre's theory appeared for the first time in an article for the
general reader on science and technology subjects in the December 1932
issue of Popular Science. Lemaître's theory became better known as the "Big Bang theory," a picturesque term playfully coined during a 1949 BBC radio broadcast by the astronomer Fred Hoyle, who was then still a proponent of the steady state universe and remained so until his death in 2001.
Lemaître's proposal met with skepticism
from his fellow scientists. Eddington found Lemaître's notion
unpleasant. Einstein thought it unjustifiable from a physical point of
view, although he encouraged Lemaître to look into the possibility of
models of non-isotropic expansion, so it is clear he was not altogether
dismissive of the concept. Einstein also appreciated Lemaître's argument
that Einstein's model of a static universe could not be sustained into
the infinite past.
With Manuel Sandoval Vallarta,
Lemaitre discovered that the intensity of cosmic rays varied with
latitude because these charged particles are interacting with the
Earth's magnetic field. In their calculations, Lemaître and Vallarta made use of the MIT’s differential -analyzer computer developed by Vannevar Bush.
They also worked on a theory of primary cosmic radiation and applied it
to their investigations of the sun's magnetic field and the effects of
the galaxy's rotation.
Lemaître and Einstein met on four 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; in California in January 1933; and in 1935 at Princeton. In 1933 at the California Institute of Technology,
after Lemaître 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 referring to
the theory as a whole, but only to Lemaître's proposal that cosmic rays may be the leftover artifacts of the initial "explosion".
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 achieved his greatest public recognition.
Newspapers around the world called him a famous Belgian scientist and
described him as the leader of the new cosmological physics.
He was elected a member of the Pontifical Academy of Sciences in 1936, and took an active role there, serving as its president from March 1960 until his death.
In 1941, he was elected a 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"). It was translated into Spanish in the same year and into English in 1950.
By 1951, Pope Pius XII declared that Lemaître's theory provided a scientific validation for Catholicism.
However, Lemaître resented the Pope's proclamation, stating that the
theory was neutral and there was neither a connection nor a
contradiction between his religion and his theory.
Lemaître and Daniel O'Connell, the Pope's scientific advisor, persuaded
the Pope not to mention Creationism publicly, and to stop making
proclamations about cosmology. While a devout Roman Catholic, he opposed mixing science with religion, although he held that the two fields were not in conflict.
During the 1950s, he gradually gave up part of his teaching workload, ending it completely when he took emeritus
status in 1964. In 1962, strongly opposed to the expulsion of French
speakers from the Catholic University of Louvain, he created the ACAPSUL
movement together with Gérard Garitte to fight against the split.
During the Second Vatican Council of 1962–65 he was asked by Pope John XXIII to serve on the 4th session of the Pontifical Commission on Birth Control.
However, since his health made it impossible for him to travel to Rome –
he suffered a heart attack in December 1964 – Lemaître demurred,
expressing surprise that he was chosen. He told a Dominican
colleague, Père Henri de Riedmatten, that he thought it was dangerous
for a mathematician to venture outside of his area of expertise. He was also named Dometisc prelate (Monsignor) in 1960 by Pope John XXIII.
At the end of his life, he was increasingly devoted to problems of numerical calculation. He was a remarkable algebraicist and arithmetical calculator. Since 1930, he had used the most powerful calculating machines of the time, the Mercedes-Euklid. In 1958 he was introduced to the University's Burroughs E 101,
its first electronic computer. Lemaître maintained a strong interest in
the development of computers and, even more, in the problems of language and computer programming.
He died on 20 June 1966, shortly after having learned of the discovery of cosmic microwave background radiation, which provided further evidence for his proposal about the birth of the universe.
Work
Lemaître was a pioneer in applying Albert Einstein's theory of general relativity to cosmology. In a 1927 article, which preceded Edwin Hubble's landmark article by two years, Lemaître derived what became known as Hubble's law and proposed it as a generic phenomenon in relativistic cosmology. Lemaître also estimated the numerical value of the Hubble constant.
However, the data used by Lemaître did not allow him to prove that
there was an actual linear relation, which Hubble did two years later.
Einstein was skeptical of this paper. When Lemaître approached Einstein at the 1927 Solvay Conference, the latter pointed out that Alexander Friedmann
had proposed a similar solution to Einstein's equations in 1922,
implying that the radius of the universe increased over time. (Einstein
had also criticized Friedmann's calculations, but withdrew his
comments.) In 1931, his annus mirabilis, Lemaître published an article in Nature setting out his theory of the "primeval atom."
Friedmann was handicapped by living and working in the USSR, and died in 1925, soon after inventing the Friedmann–Lemaître–Robertson–Walker metric.
Because Lemaître spent his entire career in Europe, his scientific work
is not as well known in the United States as that of Hubble or
Einstein, both well known in the U.S. by virtue of residing there.
Nevertheless, Lemaître's theory changed the course of cosmology. This
was because Lemaître:
- Was well acquainted with the work of astronomers, and designed his theory to have testable implications and to be in accord with observations of the time, in particular to explain the observed redshift of galaxies and the linear relation between distances and velocities;
- Proposed his theory at an opportune time, since Edwin Hubble would soon publish his velocity-distance relation that strongly supported an expanding universe and, consequently, Lemaître's Big Bang theory;
- Had studied under Arthur Eddington, who made sure that Lemaître got a hearing in the scientific community.
Both Friedmann and Lemaître proposed relativistic cosmologies
featuring an expanding universe. However, Lemaître was the first to
propose that the expansion explains the redshift of galaxies. He further concluded that an initial "creation-like" event must have occurred. In the 1980s, Alan Guth and Andrei Linde modified this theory by adding to it a period of inflation.
Einstein at first dismissed Friedmann, and then (privately)
Lemaître, out of hand, saying that not all mathematics lead to correct
theories. After Hubble's discovery was published, Einstein quickly and
publicly endorsed Lemaître's theory, helping both the theory and its
proposer get fast recognition.
Lemaître was also an early adopter of computers for cosmological
calculations. He introduced the first computer to his university (a Burroughs E 101) in 1958 and was one of the inventors of the Fast Fourier transform algorithm.
In 1933, Lemaître found an important inhomogeneous solution of Einstein's field equations describing a spherical dust cloud, the Lemaître–Tolman metric.
In 1931, Lemaitre was the first scientist to propose the
expansion of the universe was actually accelerating which was confirmed
observationally in the 1990s through observations of very distant Type
IA supernova with the Hubble Space Telescope which led to the 2011 Nobel Prize in Physics.
In 1948 Lemaître published a polished mathematical essay "Quaternions et espace elliptique" which clarified an obscure space. William Kingdon Clifford had cryptically described elliptic space in 1873 at a time when versors
were too common to mention. Lemaître developed the theory of
quaternions from first principles so that his essay can stand on its
own, but he recalled the Erlangen program in geometry while developing the metric geometry of elliptic space. H. S. M. Coxeter, another contributor to elliptic geometry, summarized Lemaître's work for Mathematical Reviews.
Lemaître was the first theoretical cosmologist ever nominated in
1954 for the Nobel Prize in physics for his prediction of the expanding
universe. Remarkably, he was also nominated for the 1956 Nobel prize in
chemistry for his primeval-atom theory.
Honors
On 17 March 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, Théophile de Donder and Marcel Dehalu. The same year he received the Mendel Medal of the Villanova University.
In 1936, Lemaître received the Prix Jules Janssen, the highest award of the Société astronomique de France, the French astronomical society.
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 1953, he was given the inaugural Eddington Medal awarded by the Royal Astronomical Society.
In 2005, Lemaître was voted to the 61st place of De Grootste Belg ("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 Les plus grands Belges ("The Greatest Belgians"), a television show of the RTBF.
On 17 July 2018, Google Doodle celebrated Georges Lemaître's 124th birthday.
On 26 October 2018, an electronic vote among all members of the International Astronomical Union voted 78% to recommend changing the name of the Hubble law to the Hubble–Lemaître law.
Namesakes
- The lunar crater Lemaître
- Lemaître coordinates
- Lemaître observers in the Schwarzschild vacuum frame fields in general relativity
- Minor planet 1565 Lemaître
- The fifth Automated Transfer Vehicle, Georges Lemaître ATV
- Norwegian indie electronic band Lemaitre
Bibliography
- G. Lemaître, Discussion sur l'évolution de l'univers, 1927
- G. Lemaître, L'Hypothèse de l'atome primitif, 1931
- G. Lemaître, The Primeval Atom – an Essay on Cosmogony, D. Van Nostrand Co, 1946.
- "The Primeval Atom," in Munitz, Milton K., ed., Theories of the Universe, The Free Press, 1957.
- Lemaître, G. (1931). "The Evolution of the Universe: Discussion". Nature. 128 (3234): 699–701. Bibcode:1931Natur.128..704L. doi:10.1038/128704a0.
- Lemaître, G. (1927). "Un univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extragalactiques". Annals of the Scientific Society of Brussels (in French). 47A: 41.
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- (Translated in: Lemaître, G (1931). "A Homogeneous Universe of Constant Mass and Growing Radius Accounting for the Radial Velocity of Extragalactic Nebulae". Monthly Notices of the Royal Astronomical Society. 91 (5): 483–490. Bibcode:1931MNRAS..91..483L. doi:10.1093/mnras/91.5.483.)
- Lemaître, Georges (1931-05-09). "The Beginning of the World from the Point of View of Quantum Theory". Nature. 127 (3210): 706. Bibcode:1931Natur.127..706L. doi:10.1038/127706b0. Retrieved 2012-02-28.
