Stefan U. Egelhaaf (1963–2023)

Sadly, Stefan left us in November 2023. He studied physics and pharmacy at the Universities of Tübingen and Kiel. In 1995 he received his PhD in biology from ETH Zürich. From 1995 to 1998 he was an instrument scientist at the Institute Laue Langevin in Grenoble, working on the D22 beamline, where he pioneered time-resolved small-angle neutron scattering experiments for the investigation of shape and phase transitions in surfactant systems. Moving to the University of Edinburgh in 1998, he continued his work there on soft matter. In 2004 Stefan was appointed to a chair in “experimental physics of condensed matter” at the Heinrich-Heine University Düsseldorf.

Stefan Egelhaaf’s scientific contributions spanned the whole field of soft matter. His main areas of research concerned the non-equilibrium behaviour of colloidal dispersions, micelles and biological macromolecules. Focussing on the glass transition, gel formation and crystallization, he particularly investigated these phenomena under ­external influences and stimulating fields. He used a broad spectrum of experimental methods, ranging from static and dynamic light, neutron scattering, to confocal and digital Fourier microscopy. Stefan’s versatility and breadth of interests were demonstrated by highlights such as the discovery of a new glass state in strongly attractive particles (the so-called “attractive glass”) [1] and many other important contributions.

Throughout his research career, Stefan strived for deep understanding of complex problems, going for carefully designed ad executed experiments often combined with insightful theoretical work.

Stefan remained a hands-on experimentalist in the lab and was ­eager to develop innovative experimental techniques. In preparing manuscripts he spent much effort in reviewing and optimizing the presentation and language, because as he said “If we are not accurate in presenting our findings, how can people trust that we are accurate in performing experiments?”

Stefan was an exceptional lecturer and an enthusiastic and inspiring teacher, going out of his way to find highly pedagogical means of putting across difficult subjects, and always showing his joy for science. During the last months of his life, he was updating several chapters for a new edition of the book based on the Bombannes “Scattering by Soft Matter” summer schools.

In his research group, Stefan always kept his door open and welcomed everyone with a warm smile, an attentive ear and a sharp mind. Those of us who have had the privilege of knowing and working with Stefan personally will remember him as a brilliant, enthusiastic, sincere, humorous, and loyal colleague and friend.

Our sincere condolences to his wife Monika and two daughters for their loss.