Celebration of the work and life of Prof. Georges Lemaître, the Belgian professor that is the founder of the theory of the Big Bang.

On 23 May 2019, the Belgian Physical Society, the European Physical Society, KULeuven and UCLouvain celebrated the work and life of Monsignor Georges Lemaître (1894-1966), Professor at the University of Louvain, and founder of the theory of the Big Bang.

At this occasion an EPS Historic Event Award was bestowed to the Heilige Geest College in the historical city centre of Leuven, Belgium.  It is here that Monsignor Lemaître wrote in 1931 his famous Nature paper. In this visionary paper containing just over 450 words, he defined for the first time the idea of the Big Bang. His idea was originally met with scepticism, but gained significant support by the discovery of the cosmic microwave background (CMB) radiation by Penzias and Wilson in 1965. As a remarkable side note, the paper of Penzias and Wilson, (co-published with that of Dicke, Peebles, Roll and Wilkinson, that interprets the CMB as the a remnant of a hot and dense point) reached Prof. Lemaitre a few days before his death in 1966.

Recent satellite observations show moreover that the CMB radiation fits nearly perfectly over a large frequency domain with the Planck curve for the radiation of a black body (at a temperature of 2.725+-0001K). Since we cannot realize such a perfect black body on earth, this radiation must thus have originated from something in extraordinarily good thermal equilibrium. The only known source with such properties is the universe, in an earlier time where it was very small, hot and dense, and this represents a recent spectacular support for the concept of the Big Bang.

The unveiling of the plaquette for the EPS Historic Site Award at the entrance of the College of the Holy Spirit (Heilige Geest College) in Leuven took place in presence of the Presidents of the Belgian and European Physical Society and representatives of the sister universities KULeuven and UCLouvain. This was followed by an academic session where the importance of the work of Prof. Lemaitre was highlighted. 

On the same day the "Big Bang" route was inaugurated. This route is a thematic cycle route that has been developed by the sister universities UCLouvain and KU Leuven, the cities of Leuven and Ottignies-Louvain-la-Neuve, and the provinces of Walloon and Flemish Brabant. Along this route, starting from the statue of Georges Lemaître in Ottignies-Louvain-la-Neuve to his statue at the College of Premonstreit in Leuven, the origin and evolution of the universe are explained.

At the occasion of this festive celebration of Prof. Lemaître a book was prepared containing Lemaître's treatise "La Physique d'Einstein" in which he exposes both the special and general theory of relativity in his own very didactic words. This original work was submitted by Lemaître to earn him fellowships that launched him onto his path of ground-breaking scientific discoveries. This new book is entitled "Learning Einstein’s Physics with Georges Lemaître", and is edited by Prof. Jan Govaerts and Jean-François Stoffel of UCLouvain. It is of timely interest to young minds and of great value for the history of science. The book is available as an e-book or printed book from the Springer Editions, link:https://www.springer.com/gp/book/9783030220297

The first issue of the Belgian Journal of Physics (2021) contains an article by J. Ongena, K. Crombé & J. Govaerts on Georges Lemaitre, with several up to now unpublished findings on this very important Belgian physicist. A pdf copy of this paper can be downloaded from this link.