Obituary: Michael Herrmann

Michael Herrmann, a professor of mathematics at Technische Universität (TU) Braunschweig in Germany, passed away unexpectedly on July 21, 2024, at 51 years of age. Michael’s research focused on the intersection of applied analysis, dynamical systems, and mathematical modeling. He was widely recognized for his significant contributions to the study of wave propagation in lattices and phase-transforming systems with hysteresis.

Michael grew up in Strausberg, near Berlin, in what was then East Germany. At age 14, he enrolled in the Gauß-Gymnasium in Frankfurt (Oder): a boarding school for gifted students that specializes in science and mathematics. After graduating and working as a programmer for one year, he began to study mathematics at the Humboldt University of Berlin, which by then was part of unified Germany. Konrad Gröger’s influential lectures on analysis, functional analysis, and partial differential equations inspired Michael’s passion for these subjects and shaped his academic path.

During his doctoral studies, Michael worked with Wolfgang Dreyer at Berlin’s Weierstraß Institute. His Ph.D. research combined analysis with careful numerical experiments on multiscale behavior in lattice differential equations, and he earned his Ph.D. in mathematics from Humboldt University in 2005. Michael then held postdoctoral positions at Humboldt University and the University of Oxford. In 2011, he joined the faculty of Saarland University as an assistant professor. From 2014 to 2017, Michael was an associate professor at the University of Münster; he then accepted a position at TU Braunschweig, where he spent the last seven years of his professional career.

Throughout his career, Michael advanced the understanding of lattice differential equations like the Fermi-Pasta-Ulam-Tsingou chain. For example, he used invariance properties of an improvement operator to offer a very elegant proof of the existence and qualitative behavior of coherent waves based on constrained maximization of potential energy [1]. Michael worked with various international collaborators to study coherent structures, including unimodal and heteroclinic waves, Riemann shocks, and modulations of periodic waves. He also made fundamental contributions to the Fokker-Planck equations that describe particle systems in a nonconvex landscape that are driven by a dynamical constraint, and their connections to rate-independent systems with hysteresis.

Michael connected with the wider applied mathematics community by regularly attending SIAM conferences and other meetings. He organized numerous minisymposia at SIAM conferences associated with the SIAM Activity Group (SIAG) on Dynamical Systems and the SIAG on Nonlinear Waves and Coherent Structures. Most recently, he organized two minisymposium sessions and delivered a minisymposium presentation at the 2024 SIAM Conference on Nonlinear Waves and Coherent Structures, which took place in June 2024 in Baltimore, Md.

Beyond his research endeavors, Michael was a dedicated teacher who devoted an enormous amount of time to preparing lectures and writing comprehensive lecture notes. He routinely offered a lab class called “Mathematics with Mathematica” to introduce students of all levels to the interactions between mathematics and computing in a variety of applications. Michael had a remarkable talent for explaining complicated concepts in a clear and accessible manner. As an advisor of three Ph.D. theses and numerous bachelor’s and master’s theses, he will be remembered for his patience and unwavering support.

Everybody who had the pleasure of meeting Michael knows that discussing any mathematical topic with him was always easy and enjoyable. He devoted his full attention to every discussion, and his sharp mind and unique perspective often shed new light on complex problems. Above all, his sense of humor made him an invaluable conversationalist.

With his passing, Michael’s collaborators, students, and the mathematics community as a whole have lost an exceptional colleague, inspiring mentor, and loyal friend.

References
[1] Herrmann, M. (2010). Unimodal wavetrains and solitons in convex Fermi-Pasta-Ulam chains. Proc. Roy. Soc. Edinburgh: Sect. A Math., 140(4), 753-785.