Bruno Eckhardt

On 7 August 2019, Bruno Eckhardt of Philipps University Marburg in Germany passed away unexpectedly at the age of 59 from complications after a medical surgery. The international physics and fluid dynamics community has lost far too early an outstanding theorist, committed teacher, and a role model who never shied away from serving the scientific community in a variety of ways.

Bruno was born on 25 March 1960 in Rockenhausen, Germany. He studied physics at the Technical University of Kaiserslautern and at the Georgia Institute of Technology in Atlanta. In 1986 he defended his doctorate in Bremen on chaotic and quantum chaotic systems. After a stay at Forschungszentrum Jülich, Bruno became an assistant professor in Marburg and defended his habilitation in 1992 on quantum chaos and periodic orbit quantization. His review on this topic is still widely read and quoted.

Directly after his habilitation, Bruno was appointed to the Carl von Ossietzky University in Oldenburg. In 1996 he returned to Philipps University Marburg as full professor. Here, Bruno turned his interest to hydrodynamics and in particular to the transition to turbulence. In pipe flow, Couette flow, and other shear flows, turbulence does not occur through linear instability and bifurcations. Rather, it emerges suddenly in a way that corresponds to a chaotic saddle in state space, as Bruno and his colleagues recognized thanks to numerical simulations and theoretical modeling. If a system is given enough time, turbulence can die out again. Bruno discovered the so-called edge states in the pipe flow, which are a crucial element in the transition to turbulence. And he elucidated the role of coherent structures in turbulence transition in further shear flows and established their connection to chaos theory. Together, his contributions to turbulence research are significant and lasting.

Bruno’s interest in chaotic dynamics extended to many other systems, especially biological systems. He was significantly involved in the foundation of the Loewe Center for Synthetic Microbiology in Marburg and was its director from 2010. He also wrote an accessible primer on chaos. A topic that also excited the general public was Bruno’s model for the collective synchronization phenomenon on the Millennium Bridge in London through the steps of a large crowd of people, which was noticed immediately after its opening in 2000 and led to stability problems.

Another of Bruno’s passions was scientific publishing and the self-organization of the scientific community. He was associate editor of the journals Physical Review E, Nonlinearity, and Nonlinear Science. He edited Physik Journal, the member magazine of the German Physical Society (DFG), and several books. Bruno was a member of the DFG’s Senate and Joint Committee for many years and played a leading international role in the governing bodies of IUTAM and EUROMECH.

Bruno received many national and international honors and awards. In 2002 he was awarded the DFG’s Leibniz Prize. He was also a Fellow of the American Physical Society, the UK’s Institute of Physics, and EUROMECH.

We have lost a special student, friend, colleague, teacher, and mentor who, through his selfless commitment to the interests of others, was a role model. Bruno had a lasting and positive influence on the scientific community. We will miss his sharp spirit, his constructive criticism, and his tireless commitment to the welfare of the community.

Our sympathy goes especially to Bruno’s wife, Kirsten, and the three daughters he leaves behind.

Adapted from the obituary written (in German) for Physik Journal.