Big Bang & Cosmology
The theory that the universe began from an unimaginably hot, dense state roughly 13.8 billion years ago was not invented by an atheist looking to dethrone God. It was proposed in 1927 by a Belgian Catholic priest, Fr. Georges Lemaître, who insisted to the end of his life that science and faith are distinct paths to the truth — neither to be confused, neither to be dismissed.
Fr. Georges Lemaître (1894–1966)
Catholic priest. Mathematician. Cosmologist. World War I artillery officer. Professor at the University of Louvain. Member, then president, of the Pontifical Academy of Sciences. Father of the Big Bang theory.
A Quick Sketch of His Life
Lemaître was born in Charleroi, Belgium, in 1894 into a devout Catholic family. He entered a Jesuit school as a boy and decided very early that he wanted to be both a priest and a scientist. The First World War interrupted his studies; he served as an artillery officer in the Belgian army and was decorated with the Croix de Guerre.
After the war he completed doctorates in mathematics at Louvain (1920) and later at MIT (1927), studied at Cambridge under Sir Arthur Eddington, and was ordained a priest of the Archdiocese of Mechelen-Brussels in 1923. He spent most of his career as professor of physics at the Catholic University of Louvain.
He wore the Roman collar to his physics lectures. He celebrated daily Mass. He was, by every account of those who knew him, a serene and good-humored man, equally at home in a chapel and at a chalkboard.
The 1927 Paper
In 1927, Lemaître published a paper in the obscure Annales de la Société Scientifique de Bruxelles with a long French title that translates as “A homogeneous universe of constant mass and increasing radius accounting for the radial velocity of extragalactic nebulae.” Buried in the technical equations was an astonishing claim: the universe is expanding, and the expansion can be measured.
Lemaître had derived the result independently of Einstein's general relativity solutions, and from it he extracted what is now called Hubble's law: distant galaxies recede from us at speeds proportional to their distance. He even calculated a value for what would become the Hubble constant — two years before Edwin Hubble's famous 1929 observational paper.
Because the journal was Belgian and the paper in French, the result went largely unnoticed in the English-speaking world. It was Eddington who rescued it and arranged for an English translation in 1931.
Einstein's Famous Misjudgment
In 1927, Lemaître cornered Einstein at the Solvay Conference in Brussels. Einstein listened, but dismissed the work with a famous phrase:
“Your calculations are correct, but your physics is abominable.”
— Albert Einstein to Lemaître, Solvay 1927
Einstein wanted a static, eternal universe. He had even introduced an arbitrary “cosmological constant” into his equations specifically to keep the universe from expanding or contracting. The idea of a universe with a beginning seemed to him — for both aesthetic and metaphysical reasons — an inelegant intrusion of theology into physics.
By 1933, after Hubble's observations and a second meeting with Lemaître at Mount Wilson Observatory in California, Einstein publicly recanted: “This is the most beautiful and satisfactory explanation of creation to which I have ever listened.” Einstein later called the cosmological constant his “greatest blunder.”
The “Primeval Atom”
In a 1931 paper in Nature, Lemaître took the next step. If the universe is expanding, then in the past it must have been smaller, denser, hotter. Run the film backwards far enough and you reach an initial moment of extreme density — a state Lemaître poetically called l'atome primitif, the “primeval atom.”
“The evolution of the world can be compared to a display of fireworks that has 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.”
— Lemaître, The Primeval Atom (1946)
“Big Bang” — A Mocking Nickname That Stuck
The phrase “Big Bang” was coined in a 1949 BBC radio broadcast by the British astronomer Sir Fred Hoyle, who detested the theory and championed a rival “steady-state” model. Hoyle meant the term as ridicule: a religious-sounding singular event, suspiciously close to Genesis. The name stuck. Hoyle's steady-state model died with the discovery of the cosmic microwave background in 1965. Lemaître, who lived just long enough to learn of that discovery from his hospital bed, was vindicated.