Karl Syassen (1945-2023)

Karl Syassen (1945-2023)Karl Syassen (1945-2023)

With the sudden and unanticipated death of Karl Syassen on December 21, 2023, the worldwide high-pressure community lost one of its most outstanding members. Karl was born in Eldagsen (Springe), Germany on August 8, 1945. He is survived by his wife Viktoria, his sons Niels and Arne, and their families.

Karl grew up in Hannover, Germany, and began his studies in Physics at the Technical University of Hannover in 1968. He then switched to the Technical University of Munich where he completed his Diplom (Masters) thesis in 1971 in the group of Wilfried Holzapfel (Mößbauer Institute), where one of us (JS) as a Postdoc also began his high-pressure research. Karl then followed W. Holzapfel to the new Max-Planck-Institute in Stuttgart for his doctoral research. During this MPI-founding phase, Karl played a pivotal role in the formation of the MPI's high-pressure laboratory, first in downtown Stuttgart and then in the new MPI research center near the campus of the University of Stuttgart.

Fascinated by exploring the world of high-pressure science with new, innovative technologies, Karl was one of the first European physicists to both use and advance the diamond-anvil-cell technology in wide fields of high-pressure physics. After completing his PhD degree in Stuttgart in 1974, he spent 1976-1977 as a Postdoc at the IBM Research Lab in San Jose, California. He then returned to the University of Düsseldorf where he introduced high-pressure physics and completed his 'Habilitation' in 1985. In October 1985 Karl was selected by the MPI Stuttgart to become the head of the high-pressure laboratory. Over the next three decades, he continued to identify and explore new opportunities in high-pressure research and advance experimental techniques in the field. This enabled him and his collaborators to make numerous, often highly influential, scientific contributions to high-pressure research and solid-state physics more generally. In recognition of these exceptional contributions, the University of Stuttgart conferred on Karl an Honorary Professorship in 1997. He also remained closely associated with the MPI Stuttgart until his death.

Karl was very open to welcoming new members and visitors to his group, showing great generosity in sharing his expertise across the breadth of solid state physics and in high-pressure science. His exceptional scientific thoroughness along with his constructively critical assessment of experimental and computational results and their interpretation were exemplary. At the same time, Karl strived for a fair scientific exchange and for giving credit where credit was due. His calm, friendly, engaging, and forward-looking personality provided the atmosphere that led to a multitude of fruitful collaborations over the years. Through all this, Karl built a leading research group that attracted many guests from all over the world, and he was highly influential on many who worked with him, and beyond.

In 2013 Karl Syassen was decorated with the Bridgman Award, the most prestigious award of the International Association for the Advancement of High Pressure Science and Technology (AIRAPT), thus honoring his many contributions to high-pressure physics.

Karl was far more than just a leading scientist in his field. He was a reserved, honest, and highly respected human being who enjoyed engaging with his colleagues and friends on every level. He shared a daily 'coffee hour' with his group. In his later years he researched the many interconnections between art, science and mathematics. We will gratefully remember all the interactions and activities shared with Karl. We will always cherish these memories!

(Contributed by Wilfried Holzapfel, Ingo Loa, James Schilling)

(The authors gratefully acknowledge the help and information given to them by Karl's son Niels Syassen, Reinhard Kremer, Jochen Mannhart, Pascal Reiß and others)