Ivan T. Todorov (1933-2025)

It is with great sadness that IHES shares the news of the passing of Ivan T. Todorov, a towering figure in mathematical physics and a long-standing visitor to the Institute, with 34 visits between 1967 and 2022.

A prolific researcher with over 350 publications and 11 books, Todorov made significant contributions to quantum field theory, conformal theories, and group theory in physics. He was a member of the Bulgarian Academy of Sciences.

After completing his thesis in Dubna in 1963 under the supervision of Nikolaï Bogolioubov, he played a key role in developing the axiomatic approach to quantum field theory. His collaborations included renowned French theoretical physicists such as Louis Michel, Claude Itzykson, Raymond Stora, and Michel Dubois-Violette, as well as leading mathematicians like Victor Kac, with whom he often collaborated at IHES.

A close colleague of Louis Michel, the first Permanent Professor of Physics at IHES, Todorov co-edited Symmetries in Nature – The Scientific Work of Louis Michel (World Scientific Publishing) with Thibault Damour and Boris Zhilinski.

Read Ivan Todorov’s reflections on mathematical physics, published in The Unravelers by Jean-François Dars, Annick Lesne, and Anne Papillaut here.

Read the personal tributes to Ivan Todorov by Jürg Fröhlich and Junchen Rong here.

The Institute wishes to thank Jean-Pierre Bourguignon, former IHES Director and Nicolaas Kuiper Honorary Professor, for his contribution to this article.

Photo credit: © Jean-François Dars