Georges-Henri Lemaitre and the Birth of the Universe

Meet the Jesuit Priest who discovered the Big Bang Theory

Big Bang
This graphic shows the evolution of the universe, and particularly the massive galaxies it contains, since the formation event of the cosmos, called the Big Bang. NASA/Niels Bohr Institute/STScI

Georges-Henri Lemaitre was the first scientist to figure out the basics of how our universe was created. His ideas led to the theory of the "Big Bang", which began the expansion of the universe and influenced the creation of the first stars and galaxies. His work was once ridiculed, but the name "Big Bang" stuck and today this theory of the first moments of our universe is a major part of astronomy and cosmology studies.

Big Bang, conceptual image
The concept of the Big Bang that Lemaitre put forth began a renaissance in scientific thinking about the conditions in the early universe. HENNING DALHOFF / Getty Images

Early Life

Lemaitre was born in Charleroi, Belgium on July 17, 1894. He studied humanities at a Jesuit school before entering the civil engineering school of the Catholic University of Leuven at the age of 17. When war broke out in Europe in 1914, he put his education on hold to volunteer in the Belgian army. For his service during the war, Lemaitre was awarded the Military Cross with palms.

After leaving the army, Lemaitre resumed his studies, concentrating on physics and mathematics as he prepared for the priesthood. He earned a doctorate in 1920 from the Université Catholique de Louvain (UCL) and moved on to the Malines seminary, where he was ordained as a priest in 1923. 

The Curious Priest

Georges-Henri Lemaitre had an insatiable curiosity about the natural world and how the objects and events we observe came into being. During his seminary years, he discovered Einstein's theory of relativity. After his ordination, he studied at the University of Cambridge's solar physics laboratory from 1923–24), and then moved to the United States to study at Massachusetts Institute of Technology (MIT). His research introduced him to the works of American astronomers Edwin P. Hubble and Harlow Shapley, both of whom studied the expanding universe. Hubble went on to make discoveries that proved the universe was larger than the Milky Way.

An Explosive Theory Gains Ground

In 1927, Lemaitre accepted a full-time position at University College London and released a paper that focused the astronomy world's attention on him. It was called 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 (radial velocity: Velocity along the line of sight toward or away from the observer) of extragalactic nebulae).

The Cepheid variable in Andromeda that Hubble observed.
This Hubble image shows the Andromeda Galaxy and the variable star that Edwin P. Hubble used to determine the distance to Andromeda. His work was based on Henrietta Leavitt's work on the period-luminosity relationship. The upper right image is a closeup of the starfield. The lower right image shows his chart and notes upon discovery. NASA/ESA/STScI

Lemaitre's paper explained the expanding universe in a new way, and within the framework of the General Theory of Relativity. Initially, many scientists—including Albert Einstein himself—were skeptical. However, further studies by Edwin Hubble seemed to prove the theory. Initially called the "Big Bang Theory" by its critics, scientists adopted the name because it seemed to work well with the events that occurred in the beginning of the universe. Even Einstein was won over, standing and applauding at a Lemaitre seminar, saying "This is the most beautiful and satisfactory explanation of creation to which I have ever listened."

Georges-Henri Lemaitre continued to make advances in science the rest of his life. He studied cosmic rays and worked on the three-body problem. This is a classical problem in physics where the positions, masses, and velocities of three bodies in space are used to figure out their motions. His published works include Discussion sur l'évolution de l'univers (1933; Discussion on the Evolution of the Universe) and L'Hypothèse de L atoms primitif (1946; Hypothesis of the Primeval Atom).

On March 17, 1934, he received the Francqui Prize, the highest Belgian scientific award, from King Léopold III, for his work on the expanding universe. In 1936, he was elected a member of the Pontifical Academy of Sciences, where he became the president in March 1960, remaining so until his death in 1966. He was also named prelate in 1960. In 1941, he was elected member of the Royal Academy of Sciences and Arts of Belgium. In 1941, he was elected member of the Royal Academy of Sciences and Arts of Belgium. In 1950, he was given the decennial prize for applied sciences for the period 1933-1942. In 1953 he received the very first Eddington Medal award of the Royal Astronomical Society.

Later Years

Lemaitre's theories were not always in favor, and some scientists, such as Fred Hoyle were openinly critical of it. However, in the 1960s, new observational evidence from the Arno Penzias and Robert Wilson, two researchers at Bell Labs, uncovered a background radiation event that was ultimately shown to be the light "signature" of the Big Bang. This was in 1964 and Lemaitre, who was in failing health, was buoyed by the news. He died in 1966, and his theories have actually been proven to be largely correct.

Fast Facts

  • Georges LeMaitre trained to become a Catholic priest at the same time he studied physics and astronomy.
  • Lemaitre was a contemporary of astronomers Edwin P. Hubble and Harlow Shapley.
  • His work ultimately predicted the Big Bang theory, which is the creation of the universe, some 13.8 billion years ago.

Sources

  • “Profile: Georges Lemaître, Father of the Big Bang | AMNH.” American Museum of Natural History, www.amnh.org/learn-teach/curriculum-collections/cosmic-horizons/profile-georges-lemaitre-father-of-the-big-bang.
  • Shehab Khan @ShehabKhan. “Everything You Need to Know about Georges Lemaître.” The Independent, Independent Digital News and Media, 17 July 2018, www.independent.co.uk/news/science/georges-lemaitre-priest-universe-expanding-big-bang-hubble-space-cosmic-egg-astronomer-physics-a8449926.html.
  • User, Super. “'A Day Without Yesterday': Georges Lemaitre & the Big Bang.” Catholic Education Resource Center, www.catholiceducation.org/en/science/faith-and-science/a-day-without-yesterday-georges-lemaitre-amp-the-big-bang.html.

Revised and edited by Carolyn Collins Petersen.