Georges Lemaître was a Catholic priest and military veteran who in the 1920s and 1930s made astonishing theoretical discoveries that overturned the steady-state universe, the eternal unchanging universe that astronomers had believed in for millennia. Father Lemaître argued that the universe had a creation in time and space, and it was a physical rather than metaphysical occurrence. He was a priest and scientist who kept his roles separate, arguing for a physical beginning of a universe the mysteries of which provided fodder for the metaphysician, the theist, and the Roman Catholic, to contemplate.

The development of science over time from the ancient Greeks and Aristotle through the Middles Ages and thinkers such as William of Ockham and Thomas Aquinas into the Renaissance and the development of the Scientific Revolution heralded by Nicholas Copernicus to, for the last five hundred years, modern science, influenced by skeptics such as Descartes and other French thinkers and scientists such as Michel de Montaigne, Jean Louis Berlandier, and Louis Pasteur, has reached a point in the twenty-first century where scientists are confident that in time most questions of the universe will be answered. As Paul Davies proclaimed in God and the New Physics, “science has actually advanced to the point where what were formerly religious questions can be seriously tackled.”

The promise of science to replace religion as the answer to the great questions of existence has, however, proved elusive. Even so great a savant as Stephen Hawking believed that the origin of the universe is ultimately unknowable, which is not part of the purview of science anyway because there is no physical evidence of what existed before the creation.

Scientists refer to the Big Bang as a singularity, an unknown of mass and potential energy that at a point, the beginning of time and space, exploded and expanded into the universe that we have today. Long before Einstein proclaimed that mass is energy at rest and energy is mass in motion the Book of Genesis had proclaimed that “In the beginning God created the heaven and the earth.” The theologian and philosopher Augustine in The City of God argued that God precedes time and space, that God is the origin of what modern physicists refer to as the singularity.

Ironically—or, perhaps there is no irony involved at all—the scientist who first conjectured the Big Bang was a Catholic priest, the Belgian Georges Henri Joseph Édouard Lemaître, a veteran of World War I, a Ph.D. physicist and mathematician who in 1927 published a paper in an obscure scientific journal that few scientists read arguing for a unique interpretation of the universe that was not steady-state nor eternal and infinite rather a universe that was expanding. In 1931 in the journal, Nature, he elaborated on this theory suggesting that such an expanding universe must have a point of a beginning and from this point expanded throughout billions of years into a universe without a clear center.

Lemaître did not refer to this point of origin, what physicists term the singularity, as the Big Bang, rather as a “primeval atom.” What was exciting for some and concerning for others was that the scientist who proclaimed this beginning of an expanding universe was not just a physicist, but a Roman Catholic priest as well, having been ordained in 1923. Lemaître was aware of the disparity in his roles, that he lived at a time when scientists were distancing themselves from religion and God opting for completely secular explanations of the universe. Many scientists refused at first to accept such an idea of a primeval atom as being beyond the scope of scientific investigation therefore irrelevant. Science only deals with perceived phenomena, not miraculous moments and supernatural beginnings. Lemaître himself tried to separate his work as a scientist from his role as a priest. In the 1931 Nature article he made no reference to God or a divine creation. He wrote that “the beginning of the world happened a little before the beginning of space and time,” in other words the moment of creation was the moment when space and time were created. It is possible, he continued to “conceive the beginning of the universe in the form of a unique atom, the atomic weight of which is the total mass of the universe.” This atom he called the primeval atom. “This highly unstable atom would divide in smaller and smaller atoms by a kind of super-radioactive process. Some remnant of this process might . . . foster the heat of the stars until our low atomic number atoms allowed life to be possible.” This was in brief the theory of what came to be called the Big Bang.

Interestingly, in the original draft of the article, which is a very brief four paragraphs, Lemaître added a fifth, subsequently crossed out and not published, in which he wrote: “I think that everyone who believes in a supreme being supporting every being and every [action], believes also that God is essentially hidden and may be glad to see how present physics provides a veil hiding the creation.” This fascinating comment implies that Lemaitre realized that his theory of the primeval atom would be recognized by theists as the Divine Creator. That he marked it out implies that he did not want to mix science and religion in his 1931 paper. But he did not need to worry, because his theory of the primeval atom begged the question of who or what caused it, which science cannot explain; this is the limit of science, which is not able to explain anything beyond the physical phenomena of the universe—hence cannot explain the Prime Mover, the Creator, God.

Lemaître’s words in the crossed out fifth paragraph of the 1931 article in Nature–“that God is essentially hidden” by what occurred before the primeval atom, which provides “a veil hiding the creation”–are particularly revealing. The promise of science ultimately falls short. Humans cannot know everything, despite the enthusiastic progressivism of the eighteenth-century Enlightenment, nineteenth-century positivism, and the humanistic philosophers, such as Julian Huxley, of the twentieth century. The ultimate cause of all things, the ultimate force in existence, the ultimate source of life, the ultimate being—is ultimately unknown to us. We gather knowledge about this Being from studying nature, God’s handiwork, the Elder Scripture, as well as from God’s revealed word, the Scripture of the Old and New Testament.

The varied articles in Catholic Exchange during the past four months, beginning with the first, “Piety and Science: The Paradigm Shift,” have explored the relationship between piety and science over the course of the past 2500 years. As we come to the end of the series with this essay on Georges Lemaître, we come to the end, the limit as it were, of piety, which might be the ultimate expression of piety. Human reason, mathematics, physical science, and technology have penetrated so many secrets of the earth and universe, but there is a limit. Lemaitre reached the limit, beyond which human knowledge cannot go, and where only faith can venture: the unknowable before the beginning, which in contemplating we can only do so in awe and wonder.

This article originally appeared in the online journal, Catholic Exchange.

This article was featured in the podcast “When Science Hits the Wall: Piety, Georges Lemaitre, and the Big Bang, presented by Claymore: Become who you are: Bing Videos