Georges Lemaître was a distinguished Belgian Catholic priest, theoretical physicist, and mathematician born on July 17, 1894, in Charleroi, Belgium. He received his education at the Catholic University of Louvain, studying both engineering and philosophy, obtaining his baccalaureate in thomistic philosophy in 1919, before being ordained as a priest of the Archdiocese of Mechelen in 1923. With the support of his mentor Cardinal Désiré-Joseph Mercier, Lemaître pursued advanced studies abroad, working with Arthur Eddington at the University of Cambridge in 1923-1924 and with Harlow Shapley at the Harvard College Observatory and MIT in 1924-1925. In 1927, he was appointed Professor at the Catholic University of Louvain, where he remained for the remainder of his academic career, establishing himself as a leading figure who seamlessly integrated scientific inquiry with religious faith.
Lemaître's groundbreaking contribution to cosmology came in 1927 when he published 'Un Univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extra-galactiques,' presenting the first formulation of what would become known as the expanding universe theory. Through rigorous mathematical analysis of Einstein's field equations in general relativity, he demonstrated that the universe is not static but expanding, with velocity proportional to distance—a relationship now recognized as the Hubble-Lemaître law. His work predated and anticipated Edwin Hubble's observational confirmation of galactic redshifts in 1929, though his initial paper was largely overlooked due to its publication in a less widely-read journal. Building on this foundation, Lemaître proposed his revolutionary 'hypothesis of the primeval atom' in the 1930s, which posited that the universe began in an extremely hot, dense state and has been expanding ever since—a concept now recognized as the first formulation of the Big Bang theory.
Lemaître's visionary ideas fundamentally transformed our understanding of cosmic origins and established the theoretical framework for modern cosmology. Though initially met with skepticism, even from Einstein who favored a static universe model, his work gained widespread acceptance as astronomical evidence mounted in favor of an expanding universe. His concept of the primeval atom evolved into the modern Big Bang theory, which was dramatically confirmed in 1965 by the discovery of cosmic microwave background radiation by Arno Penzias and Robert Wilson. Lemaître's lasting legacy includes not only his specific cosmological theories but also his pioneering integration of rigorous mathematical physics with astronomical observation, demonstrating that religious belief and scientific inquiry can coexist harmoniously. His work continues to influence contemporary cosmological research, serving as the cornerstone of our current understanding of the universe's origin, evolution, and structure.
