after the fire, scientists help rediscover the fascinating history of the cathedral
Notre-Dame now has a “digital twin”. It is perhaps this image that best summarizes the work carried out by more than 200 scientists since spring 2019. Starting from the idea of linking the characteristics of the cathedral with the data and knowledge collected, the “digital group” led by the architect and computer engineer Livio de Luca has in fact built a “cathedral of knowledge” by converging around a 3D model the databases produced by research from all disciplines: scans of elements architectural works, photos, material analyses, historical articles, sound recordings, etc. A titanic task to make them compatible with each other, taking into account the various “temporal states of the cathedral and their spatial location,” explains the researcher. This data will be available for free consultation from 2025.
All disciplines involved
The day after the fire, some of his colleagues mobilized to provide architects and restorers with existing information. They also offered their services to complete research on the monument. Very quickly, the CNRS (National Center for Scientific Research) and the Ministry of Culture understood the interest in supporting, coordinating and publicizing the work of researchers, brought together according to nine cross-cutting themes defined from materials – wood, stone , metal, glass – and techniques – structure, acoustics, decorations – to which are added the “emotions and mobilizations” group and, of course, the one on digitization.
In April 2024, these chemists, computer scientists, archaeologists, historians, engineers, musicologists, etc. gathered in a conference, gave a first glimpse of the interest of such interdisciplinary research, carried out from a common “object” (the cathedral). ). Thus, the chronology of the construction of Notre-Dame was able to be clarified thanks to several studies: remains of wooden rods found imprisoned in a matrix of mortar made it possible to affirm that the walls of the choir were completed during the winter 1171-1172. This first absolute dating was obtained using dendrochronology, a method of counting tree rings (circles visible on sections). Other dates were collected for the walls of the nave, thanks to the study of the traces of tools which evolved throughout the 12th and 13th centuries… This project therefore brought together specialists from distant disciplines.
Some have also studied the vestiges of polychromy of the portals, have dated the stained glass windows of the large roses or attempted to show the evolution of the decoration of the capitals; others have reconstructed through chemical analyzes the circuit of iron and lead used in the cathedral, while it is also a question of analyzing the remains of the rood screen brought to light during the excavations.
Artificial intelligence at the service of historians
Historians benefit from an incredible advance thanks to an artificial intelligence program which digitized and translated the 26 saved volumes of reports of the meetings of the cathedral chapter, between 1326 and 1504, i.e. 14,605 pages in Latin! “We can now query this text according to key words and follow, over the years, the life of the cathedral district, the canons’ staff, the distribution of their charitable works, the evolution of their careers…”, explain Julie Claustre and Élisabeth Lusset, spokesperson for a large team. Accessible to all, their database lists 1,112 names of people cited in these registers. “It is thus possible to follow over several generations the family of Jean de Chastenet (1414-1459), who began working at Notre-Dame as… a sow hunter, then was promoted to guardian of foundlings,” say the historians. . Likewise, the mention of 1,600 works in these registers gives an idea of the holdings of the Notre-Dame library, which is the subject of a particular study.
Faced with these innumerable avenues, nourished by these crossed approaches, a thematic group should already broaden the method, from January 2025, this time by studying “the spiers of cathedrals”. Other groups are being formed. “The Notre-Dame project remarkably demonstrates the extent to which science serves society,” observes Antoine Petit, President and CEO of the CNRS. And it allowed researchers to make it visible.
