Georges Lemaître was the main author of the big bang theory of the creation of the universe.
Both a Catholic priest and a mathematical physicist, Georges Édouard Lemaître was one of the first people to suggest the big bang theory of the creation and evolution of the universe. The theory began with his deduction that if galaxies in the universe are now moving away from each other, they must once have been closer together. Lemaître proposed that all matter in the universe was once contained in what he called a "primeval atom" before being scattered, and radically changed, by a massive explosion. The theory has been called the greatest achievement of modern cosmology.
Decides on scientific and religious career
Lemaître was born July 17, 1894, in Charleroi, Belgium, into a deeply religious family. His father, Joseph Lemaître, had received a law degree but chose a career as a glassblower; after a fire, however, he moved to Brussels where he returned to practicing law. His mother was Marguerite Lannoy Lemaître. When he was only nine years old, Lemaître had already decided to become both a priest and a scientist. "There was nothing dramatic about it," he told the New York Times Magazine. "I was a good student, especially so in the dull, hard subjects like mathematics and fascinated with the smattering of knowledge I picked up in elementary school. So I naturally followed my bent ... exactly at the same time, in the same month as I remember it, I made up my mind to become a priest." Lemaître did not see a contradiction between these ambitions: "I was interested in truth from the standpoint of salvation, you see, as well as truth from the standpoint of scientific certainty." He entered the University of Lovain, but he did not study physics; he graduated as a mining engineer in 1914.
Switches focus from engineering to physics
When World War I broke out (in 1914), Lemaître joined the Belgian Army and became an artillery officer. While in the army, he read Electricite et optique ("Electricity and Optics") by French mathematician Jules-Henri Poincaré (1854-1912), and the book made him reconsider his career as an engineer. At the end of the war, Lemaître returned to Louvain to study physics and mathematics. He finished his master's thesis in 1920.
Works with theory of relativity
After receiving his master's degree, Lemaître studied for a time toward his doctorate and then entered the seminary at Mailines, Belgium, in October 1920. He was ordained as a Roman Catholic priest in 1923. After his ordination, Lemaître won several fellowships that allowed him to study abroad. He spent 1924 studying solar physics at Cambridge University, where he first met and worked with English astronomer Arthur Eddington (1882-1944). In 1925, Lemaître went to the United States, where he studied at Harvard University and the Massachusetts Institute of Technology (MIT). He focused his studies on the application of German-born American physicist Albert Einstein's (1879-1955) theory of relativity (the relationship between measurements taken by two systems moving with respect to each other) to astronomy, and he received his doctorate from MIT in 1927. Lemaître than returned to Belgium to join the faculty at the University of Louvain.
Meets top astronomers in travels
During his time in England and the United States, Lemaître met and worked with some of the great astronomers of his time. Besides Eddington, he became acquainted with American astronomers Edwin Hubble (1889-1953), Harlow Shapley (1885-1972), and Vesto M. Slipher (1875-1969). Slipher had been measuring the radial velocities (the speed at which objects are moving toward or away from Earth along a line of sight) of galaxies since 1912 and found that most seemed to be moving away from the Milky Way, our own galaxy. Hubble, too, observed that galaxies were moving away from each other. (In 1929, he would formulate Hubble's law, which states that the distance to a galaxy and the velocity at which is moving away are directly related.) Shapley, who like Hubble worked at the Mount Wilson Observatory in California, determined the size of the Milky Way and the Sun's position within it. These advances in astronomy, as well as others, contributed to Lemaître's examination of the theory of relativity.
Formulates the big bang theory
One of the components of Einstein's original theory of relativity was the proposition that the universe was static, or unchanging, and yet could collapse if disturbed. He based this idea on a series of mathematical calculations, which he would later retract, calling them the "biggest blunder" of his career. But before Einstein realized his mistake, Lemaître had already begun to question the idea of a static universe, partly on the basis of what he had learned from the observations of American and English astronomers. In 1927, Lemaître published a paper entitled "A Homogeneous Universe of Constant Mass and Increasing Radiation, Taking Account of the Radial Velocity of Extragalactic Nebulae." Lemaître argued that if all the galaxies in the universe were speeding away from each other, they had to have been at some point in the past closer together. He envisioned the matter and energy of the universe to have been wrapped up tightly in what he called a primeval atom. He pictured this "atom," or "egg" to be about thirty times the size of the Sun but immeasurably dense.
Between twenty billion to sixty billion years ago, he believed, the egg burst in an explosion which threw matter and energy off in all directions. The expansion that began with this explosion continued until the universe was about a billion light-years wide. To explain the expansion, Lemaître postulated the existence of what he called cosmical repulsion. An opposite force to gravity, he speculated that cosmical repulsion grew stronger as objects became more distant from each other and thus kept the universe's expansion going. As a result of the big bang explosion, Lemaître believed, the original density of matter had been reduced so greatly that simple atoms like hydrogen had been able to form larger, more complex atoms. In Revue des Questions Scientifiques, Lemaître wrote: "The atom world broke up into fragments, each fragment into still smaller pieces.... The evolution of the world can be compared to a display of fireworks that had just ended: some few red wisps, ashes, and smoke. Standing on a cooled cinder, we see the slow fading of the suns, and we try to recall the vanished brilliance of the origin of the worlds."
Shares credit for big bang theory with Friedmann
Lemaître did not realize that Aleksandr Friedmann (1888-1925), a Russian meteorologist and mathematician, had challenged Einstein's assumption of a static universe five years earlier. Friedmann pointed out that Einstein had erred in the calculations he used to devise his static universe, and he reached much the same conclusion Lemaître did about the origins of the universe. The work of Friedmann and Lemaître greatly simplified the calculations necessary for the theory of relativity, and Friedmann is considered a cofounder of the big bang theory.
Theory is supported by Einstein
When first published, Lemaître's theory was considered fantastic; the New York Times called it "highly romantic." It did, however, catch the eye and imagination of the great astronomer Eddington, whom Lemaître had met during his time at Cambridge. Eddington arranged for the paper to be published in the Monthly Notices of the Royal Astronomical Society in 1931. In December 1932, Lemaître explained his view of the development of the universe in a lecture at Mount Wilson Observatory in California. Einstein was in the audience. When Lemaître concluded, as quoted in Catholic World, Einstein stood up and said: "This is the most beautiful and satisfactory explanation of creation to which I have ever listened." The two theorists afterward developed a profound admiration for each other. Dutch astronomer Willem de Sitter (1872-1934) agreed with Einstein: "There can be not the slightest doubt that Lemaître's theory is essentially true and must be accepted as a very real and important step toward a better understanding of Nature."
Mathematical framework for theory draws new support
Despite such praise, Lemaître's original theory lacked sufficient mathematical backing for widespread acceptance. Discoveries of cosmic rays (tiny particles of matter that travel through space) during the early 1930s did lend weight to the theory, but it was not until 1946, when American physicist George Gamow (1904-1968) provided much of the mathematical backing the original work had lacked, that the theory was taken seriously by most physicists. Gamow examined the big bang from just before it began, in theory, to just after it ended. He abandoned Lemaître's idea of cosmical repulsion and argued that the force of the initial explosion alone would be enough to make the universe continue to expand.
Steady-state theory challenges big bang
But in 1948, mathematician Hermann Bondi and astronomer Thomas Gold of Cambridge University suggested that there had been no bang, no creation event whatsoever. In what came to be known as the steady-state theory, Bondi and Gold argued that the universe had always existed and had never really changed. As galaxies moved out of our range of observation, new galaxies formed in the spaces in between, so the number of galaxies in view remained fairly constant. Among the supporters of the steady-state theory was the astronomer Fred Hoyle (1915-), who did much to refine and popularize it.
Radio astronomy provides big bang evidence
The two theories remained rivals throughout the 1950s and on into the 1960s, but results from the use of radio astronomy effectively disproved the steady-state theory. Because light can take so long to travel across the great distances in space, what astronomers on Earth study is actually light from stars as they existed thousands of millions of years ago. Using radio astronomy, English astronomer Martin Ryle (1918-1984) at Cambridge University showed that the distribution of distant galaxies is not the same as those closer to Earth in space and time, thus proving that the universe is changing. In 1965, the detection of cosmic microwave background radiation presented strong evidence that there had been a period of time when the universe was hot and dense--as it would have been immediately after the big bang. Although other theories continue to arise as scientists attempt to explain the beginning of the universe, Lemaître's theory with its modifications is still the most widely accepted.
Finds a harmony between two careers
After 1927, Lemaître served as a professor of astrophysics at the University of Louvain, teaching and conducting research. Throughout his career he continued to refine his theory, but he also investigated such subjects as the three-body problem (the way that three bodies, such as planets, act on each other), calculating machines, and cosmic rays. He remained, throughout his life, active in the Catholic Church. He saw no conflict between his scientific work and his religious beliefs. He once said, as quoted in the New York Times: "All problems in life can be solved either by religion or science, but not by both combined." In an interview with the New York Times Magazine, he put much of the blame for the perception of a conflict on scientists: "Once scientists can grasp that the Bible does not purport to be a textbook of science, the old controversy between religion and science vanishes." He acknowledged, however, this is more difficult for some branches of science to do than others, but physicists and astronomers "have been religious men, with a few exceptions. The deeper they penetrated into the mystery of the universe, the deeper was their conviction that the power behind the stars and behind the electrons of atoms was one of law and goodness."
Receives awards for groundbreaking theory
Lemaître was awarded the Prix Francqui in 1934. Einstein was one of his sponsors, and Eddington was among the judges. In 1935, Villanova University presented him with the Mendel Medal. That year, he also received an honorary degree from McGill University in Montreal. Lemaître died in Louvain, Belgium, on June 20, 1966. He was seventy-one years old. At the time of his death he was president of the Pontifical Academy of Sciences in Rome.
- Aikman, Duncan, "Lemaître Follows Two Paths to Truth," New York Times Magazine, February 19, 1933, pp. 3, 18.
- Cevasco, George A., "The Universe and Abbé Lemaître," Catholic World, June 1951, pp. 184-88.
- "Earth's Age Given as Two Billion Years," New York Times, July 24, 1933, p. 16.
- "Finds No Conflict of Science, Religion," New York Times, December 11, 1932.
- Gamow, George, The Creation of the Universe, Viking, 1961.
- Godart, Odon, and Michal Heller, Cosmology of Lemaître, Pachart Publishing House, 1985.
- Hartmann, William K., Astronomy: The Cosmic Journey, Wadsworth, 1987.
- Jastrow, Robert, God and the Astronomers, Norton, 1978.
- Moore, Patrick, History of Astronomy, Oldbourne, 1983.
- Moore, Patrick, The Picture History of Astronomy, Grossett & Dunlap, 1973.
- Physics Today, September 1966, pp. 119-20.
- Revue des Questions Scientifiques, November 1931.
- Rival Theories of Cosmology, Oxford University Press, 1960.
- Silk, James, The Big Bang, W. H. Freeman, 1980, pp. 20-26.