Archimedes is often presented as the first great scientist to have used his scientific knowledge to build war machines. During the Siege of Syracuse in 212 BC, he is said to have constructed giant parabolic mirrors to ignite enemy sails by concentrating the Sun’s rays. While the anecdote is certainly not true, it illustrates one of the earliest uses of science in warfare.

However, Archimedes was also a “pure” mathematician to whom we owe treatises on geometry that have marked the history of science. When a Roman legionary came to disturb him as he drew a geometric figure in the sand, he replied, “Don’t disturb my circles”, and the soldier killed him with a blow of his sword.

Much later, during the Second World War, the Manhattan Project in the United States brought together in the greatest secrecy a considerable number of engineers, physicists and mathematicians with the aim of building the first atomic bombs, far more powerful than the Archimedean mirrors. On August 6 and 9, 1945, the bombs killed more than 100,000 people in Hiroshima and Nagasaki. The whole world became fully aware of the determining role of the scientific community in the war.

At the end of the First World War, like the League of Nations, many scientific disciplines created international unions. The International Mathematical Union (IMU), for example, was founded in 1920 and organizes a very prestigious international congress every four years which takes stock of the progress of mathematics: in a way, the Olympic Games of Mathematics.

No peaceful agreement

However, we should not believe in a peaceful understanding between all the mathematicians of the world, ignoring wars and political conflicts. For example, when the IMU was founded, German mathematicians were not invited, and to mark the victory, the opening ceremony took place in Strasbourg, recently again in France. The congresses were canceled during the Second World War and very disrupted during the Cold War.

In Cambridge (United States), in 1950, no Soviet delegate or any from communist Eastern Europe took part, although several had been invited. The Soviet Academy of Sciences claimed that Soviet mathematicians had too much work to travel. The United States had initially refused the entry visa for the Frenchman Laurent Schwartz, a communist, who came to collect his Fields medal. In 1966, Alexandre Grothendieck refused to pick up his medal in Moscow. The congress which was to take place in Warsaw in 1982 was postponed and was held the following year. The history of this international mathematical union is indeed very chaotic.

Four years ago, Saint Petersburg won the competition against Paris for the organization of the congress in August 2022. Should we rebel against this choice? Some did at the time and proposed the boycott. When the war broke out in Ukraine, all mathematicians wondered if the St. Petersburg Congress would be confirmed, canceled or postponed? Already, a number of invited speakers before the war had declined the invitation for political reasons.

The solution proposed by the IMU is surprising: the congress will indeed take place, but in virtual mode, by videoconference, which is not easy in practice because of the time difference. But speakers can record their conference in advance if they wish. Will they use it to denounce the war?