Georges Lemaître: one of the Big Bang inventors

Georges Lemaître : un des inventeurs du Big Bang
Georges Lemaître: one of the Big Bang inventors

Among the scientists who contributed to the elaboration of the Big Bang theory, Mgr. Georges Lemaître is one of the most important. And yet, the astrophysicist is not well known to the general public. Here’s a quick portrait of this exceptional man.

Georges Lemaître was born in Charleroi, Belgium, on July 17, 1894, to a middle-class family. He began engineering studies at the age of 17, which he interrupted to enlist in the First Word War. After the war he returned to his studies, this time in physics and mathematics. In 1920 he earned a doctorate in science (the equivalent of a present-day master’s) with great distinction.

That same year, he entered an accelerated religious training program at the seminary in Mechlin, where he was ordained as a priest in 1923. He then was awarded a grant to go and study with astronomer Arthur Eddington in England, and then in the United States, where he met Edwin Hubble, among others.

During this time he was introduced to a revolutionary new theory, the general relativity developed by none other than Albert Einstein.

An expanding Universe

In 1925 he developed solutions to Einstein’s equations envisaging an expanding Universe. He was the second to work out that type of solutions, after the Russian physicist Alexander Friedmann, whose work had been published in a Russian journal. The same year, he submitted a doctoral thesis to the Massachusetts Institute of Technology on a similar theme, which would be accepted in 1926.

In 1927 he published an important article in which, in addition to positing an expanding Universe, he linked the redshift observed in galaxy spectra to that expansion. He even predicted a linear relationship between the distance of galaxies and their redshifts. He thus predated by two years the work of Edwin Hubble on the subject, who discovered this relationship experimentally, in 1929, without however explaining the cause of the redshift. Lemaître’s article, published in French, in Belgium, would not have as much impact as Hubble’s despite the translation Eddington did of it.

The primeval atom

Lemaître realized that if the observable Universe is expanding, it had to have been much smaller and much hotter in the distant past. In an article published in 1931, he was the first to make use of quantum mechanics, a branch of physics gaining ground at the start of the early 20th century, to explain the first moments of the Universe. He thus predicted that a relic of the early Universe must exist. That cosmic microwave background radiation would be discovered in 1964 by physicists Arno Penzias and Robert Wilson.

In 1934 he published a communication to the National Academy of Sciences of the United States in which he proposed that the vacuum of the Universe has an energy. It was only in 1998 that astronomers would discover that the rate of the Universe’s expansion turns out to be more significant than previously thought. That result is explained by a consideration that the vacuum possesses an energy that accelerates expansion of the spacetime fabric of the Universe. Once again, Lemaître had it right.

In 1945, Georges Lemaître published his major synthesis on cosmology in a book entitled The Primeval atom: A hypothesis of the origin of the universe.

After the Second World War, Lemaître devoted himself to numerical calculations with the first computers and to the development of programming languages.

He died of leukemia in 1966 in Louvain, Belgium. He would have had time to learn of the discovery of the cosmic microwave background radiation that proved the accuracy of his work in cosmology.

Georges Lemaître today is considered along with Alexandre Friedman and Georges Gamow to be one of the three fathers of the Big Bang theory.

To learn more on this subject, come see the film Horizon: Beyond the Edge of the Visible Universe, currently showing at the Planétarium.

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