In Memoriam
Johannes Elschner
(31 August 1949 – 27 May 2026)
Johannes Elschner devoted his professional life to applied mathematics, making significant contributions to scattering theory, inverse problems, diffraction, and computational wave propagation. For more than two decades he was a member of the scientific staff of the Weierstrass Institute for Applied Analysis and Stochastics (WIAS) in Berlin, where he contributed to the development of the institute's research activities and international collaborations.
Born on 31 August 1949 in Triptis, Germany, Johannes Elschner studied mathematics from 1968 to 1972 at the Technical University of Chemnitz, where he received his diploma in mathematics in 1972. From 1972 to 1979 he worked as a Scientific Assistant at the same institution. He obtained his doctorate in 1976 and continued his research in applied analysis and mathematical physics.
In 1979 he joined the Institute of Mathematics of the Academy of Sciences of the GDR as a scientific staff member. During this period he developed many of the research interests that would accompany him throughout his career. Following his habilitation in 1982, he continued his work at the Institute of Mathematics until 1991. In recognition of his scientific achievements, he was awarded the Euler Medal of the Academy of Sciences of the GDR in 1988.
In 1992 Johannes Elschner became a member of the scientific staff of the newly established Weierstrass Institute for Applied Analysis and Stochastics (WIAS). He remained at WIAS until his retirement in 2014.
Johannes Elschner started his research investigating singular differential and pseudodifferential equations. He continued with the fundamental analysis of boundary integral equations and boundary elements. Later his research focused on the mathematical analysis of direct and inverse scattering problems, inverse boundary value problems, and diffraction by periodic structures. His work combined analytical methods with numerical approaches for problems arising in acoustics, elasticity, electromagnetics, and optics. He made important contributions to the study of diffraction gratings, rough surfaces, and singular scattering phenomena, helping to strengthen the mathematical foundations of these areas.
An important part of his scientific work was his long-standing collaboration with Guanghui Hu, with whom he co-authored numerous papers on inverse scattering theory, diffraction gratings, rough surface scattering, and elastic wave propagation. Their joint research contributed to the understanding of uniqueness and reconstruction questions in inverse scattering and led to several widely cited results in the field.
Johannes Elschner also collaborated closely with Masahiro Yamamoto. Together with Guanghui Hu, they worked on inverse boundary value problems, stability estimates, and related questions in inverse scattering theory. Their publications contributed to the mathematical analysis of these problems and continue to be referenced in current research.
Throughout his career Johannes Elschner maintained extensive international collaborations and was a valued partner for researchers in Germany and abroad. Colleagues appreciated his reliability, his careful and thorough approach to mathematics, and his willingness to share his knowledge and experience.
His publications continue to serve as references for researchers working in scattering theory and inverse problems. His contributions remain part of the mathematical literature and of the scientific community to which he dedicated his career.
The Weierstrass Institute, his collaborators, former colleagues, and friends remember Johannes Elschner with gratitude and great respect.