Abbè Georges E

The Belgian astronomer Abbé Georges Édouard Lemaîtrédouard Lemaître (1894-1966) originated what came to be called the "big bang" theory of cosmogony.

Georges Lemaître was born in Charleroi on July 17, 1894. Already at age 9 he had decided to become both a scientist and a priest. He never saw any essential conflict between science and religion; later in life he is reported to have asked: "Do you know where the heart of the misunderstanding lies? It really is a joke on the scientists. They are a literal-minded lot. Hundreds of professional and amateur scientists still actually believe that the Bible pretends to teach science. This is a good deal like assuming that there must be authentic religious dogma in the binomial theorem."

At the University of Louvain, Lemaître took courses in engineering and the humanities, with emphasis on the former. By 1914 he had become a first-class civil mining engineer, and at the outbreak of World War I he joined the Belgian army. Gradually, Lemaître's interests shifted from engineering to mathematics and the physical sciences. In 1920 he obtained his doctorate in the latter subjects. Entering the Seminary of Malines, where he was permitted to continue his scientific studies, he became familiar with Albert Einstein's general theory of relativity. In 1923 he was ordained a priest. He then studied at Cambridge University, England. In America during 1924-1925 Lemaître pursued his interests in relativity, especially its cosmological implications, at Harvard University and the Massachusetts Institute of Technology. In 1925 he returned to the University of Louvain, where he was first put in charge of courses and later appointed professor.

Lemaître's most important scientific contribution, his ideas on the origin of the universe, later to be termed the "big bang" theory of cosmogony, developed at Louvain during 1925-1931. These ideas were stimulated by V. M. Silpher's observations which showed that the spectral lines of stars in nebulae are shifted toward the red end of the spectrum, which implied that these nebulae are receding from the earth. To Lemaître, this seemed inconsistent with Einstein's matter-filled static model of the universe; more promising was De Sitter's model, in which the nebulae were forced progressively farther apart. But De Sitter's model also seemed unsatisfactory to Lemaître.

In 1925 Lemaître announced his intention of exploring De Sitter's theory further. Two years later he succeeded in reconciling De Sitter's universe with Einstein's universe by an intermediate model, a matter-filled expanding universe, for which Lemaître deduced a law relating the distances of nebulae to their velocities of expansion, a law that proved to be in accord with E. P. Hubble's measurements of 1929.

In 1931 Lemaître formulated his famous hypothesis, the "big bang" theory of cosmogony, to account for the expanding universe. By Lemaître's own account, it was while reading a 1931 article on the origin and end of the world that the basic idea occurred to him. Suppose, he reasoned, we reverse a well-known process, the ever-increasing multiplication of radiant energy particles (or quanta) in the universe. If the total energy remains constant, we will then obtain at some remote time in the past only one huge energy quantum, a "primeval atom," as he termed it. This primeval atom—at the creation of the universe—must therefore have exploded in a huge fireball; and Lemaître later demonstrated how this explosion, obeying only the known laws of physics, could have produced the ever-expanding nebulae, the stars, and all other constituents of the observable universe, including the radioactive elements and the extremely highenergy cosmic rays.

Lemaître also explored a variety of fields, from cosmic rays to calculating machines. While he saw Baade's postwar researches support his cosmological time scale, he also saw his cosmogonical model challenged by the steady-state theory of H. Bondi, T. Gold, and F. Hoyle. At present, however, Lemaître's model has received additional support from the detection of a very small amount of radiation in the universe, presumably left over from the primordial fireball which burst asunder several billion years ago. Lemaître died in Louvain on June 20, 1966.

Further Reading

A general account of Lemaître's work is in Ferdinand Gonseth's preface to Lemaître's The Primeval Atom: An Essay on Cosmogony, translated by Betty H. and Serge A. Korff (1950). For background see George Gamow, The Creation of the Universe (1952), and Milton Munitz, ed., Theories of the Universe (1957). □