Georges Lemaitre & The Big Bang Theory

Instructor: Jeff Fennell

Jeff has a master's in engineering and has taught Earth science both domestically and internationally.

Georges Lemaitre was a Belgian astronomer who first proposed the idea that the universe was created from an explosion from a single point. This lesson will cover the facts of his career and his theory.


Georges Edward Lemaitre (July 17, 1894 - June 20, 1966) was a Belgian astronomer and cosmologist. He was the first to propose the modern Big Bang Theory, the theory that the universe began from the explosion of a small original 'super atom.'

Georges Lemaitre

After World War I, Lemaitre studied astronomy at the University of Cambridge where he received his Ph.D. in 1923. In that same year, Lemaitre was ordained as a priest. It was in 1927 that Lemaitre expanded on work done by Edwin Hubble in a published paper in Belgium. In this paper, Lemaitre formulated the idea of an expanding universe. Unfortunately, this paper did not receive much attention until it was translated into English in 1931.

Lemaitre returned to Belgium as an astrophysics professor at Catholic University of Louvain. The same year, Lemaitre published a rigorous solution to Einstein's field equations. The solution became known as the 'Friedman-Lemaitre-Robertson-Walker metric.' In the papers, it is mathematically shown that the universe is expanding and originated from a 'primitive atom' explosion. At that time, Russian mathematician Friedman published a similar result, but it was unknown to Lemaitre.

Big Bang Theory

The Big Bang is the most common term to describe the birth of the universe and its subsequent evolution after the initial conditions. This model has been the most widely used, studied and observed within current studies of the universe.

There is still much to be learned about general relativity. We can only understand to the extent we can observe. By observing the measurements between galaxies, scientists have calculated the age of the universe to be approximately 13.73 billion years.

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