Member of the Académie des Sciences de Paris, Professor at University Pierre et Marie Curie (Paris) since 1981, Marc Yor works as a researcher in the Laboratoire de Probabilités et Modèles Aléatoires (LPMA). The following text was written by Marc Yor for publication in EMS.
It is precisely 10 years, as this note is being written for its publication in the EMS Website around May 2010, that the Pli cacheté n°11 668, sent by Wolfgang Doeblin, then soldier Vincent Doblin from the Ardennes front in February 1940, was opened by the Commission des Plis cachetés, in the Académie des Sciences de Paris (in May 2000), and that Bernard Bru, a probabilist who specialized in the history of Probability, and myself, were asked to study the contents of the Pli.
It turned out to be an extremely rich document, in which W.D., who was just "emerging" from his Thèse d'État, under the direction of Maurice Fréchet, before being drafted as an ordinary soldier, was able to present the main martingale features of one-dimensional diffusions, thus showing a quite advanced understanding of continuous martingales, about 25 years before their well-known Dambis-Dubins-Schwarz representation as time-changed Brownian motion was established.
The publication of the entirety of the Pli, together with both historical and scientific comments as a Special Issue of the Comptes-Rendus de l'Académie des Sciences, Section Mathématiques, in December 2000, triggered deep interest about various aspects of the life and destiny of Wolfgang, extending to those of the members of his family.
Among the many consequences of the publication of this Pli, interest surged about the Doeblin family, the relationships between his famous father Alfred and Wolfgang, the early exode of Jews from Germany in 1933, the resistance to Hitler and the Nazi ideology within Germany, and many other topics... A book by Marc Petit : L'équation de Kolmogorov, was published, and two documentary films, respectively by J. Ellinghaus and H. Ferry on one hand, and by H. Willems and A. Handwerk on the other hand, were released. Several presentations of these films are made each year, without any gap during the decade.
This overall surge of interest around Wolfgang's life is all the more remarkable as, sadly enough, we may say that, among today's young probabilists, the scientific contributions of Wolfgang Doeblin are largely ignored.
There is an ongoing integral publication of the 13 Comptes Rendus Notes, and the 13 articles which, amazingly, given the circumstances, Wolfgang has been able to write and publish during the years 1936-1940. This publication of Wolfgang's oeuvres complètes is undertaken under the joint auspices of the Académie des Sciences de Paris and the Brandenburger Akademie. It aims at making the works of Wolfgang Doeblin being appreciated in their entirety.
The Introduction to this volume, by Bernard Bru, should help readers entering the world of Wolfgang's discoveries.
A few words about the origins of the Plis cachetés in the Académie des Sciences de Paris may be in order :
- it started -unfortunately- as a means of settling priority questions between the Bernoulli brothers, which, in a sense, set the standards, that is, most of the Plis have been sent to the Académie by quite original -to say the least !- people who are trying in this manner to escape peer review, in the hope of claiming later...-meaning, quite often, never !- a great discovery.
- the worthwhile exceptions to this sad state of affairs are the Plis sent in a period of trouble, e.g : war, when their authors feel that the best way to protect their writings is to have them stored away in the Archives of the Académie, waiting for better days when they can recover them.
- unfortunately, in the case of Wolfgang, these better days never came, as Wolfgang decided to kill himself in Housseras, a small town in the Vosges, in June 1940, when his regiment was being encircled by the Nazi troops.
Thus, a young mathematician -of the class of Abel and Galois, as Paul Lévy's appreciation goes- met his fate.