Hermann Haken passed away

On August 14, 2024, Hermann Haken passed away at the age of 97, surrounded by his family. He was one of the most significant physicists of the 20th and early 21st centuries, making groundbreaking contributions to laser theory, solid-state physics, the theory of non-equilibrium phase transitions in various media, and the theory of self-organization and complexity.

Beyond physics, Hermann Haken was also of great importance to various other disciplines, including psychology, psychotherapy, psychiatry, social sciences, and counseling. This is because Professor Haken and his team were quick to recognize the broad applicability of the principles of self-organization, which they had initially described and experimentally studied in lasers. Phenomena like non-equilibrium phase transitions, the « enslavement principle » in the emergence of order, information compression, critical instabilities, order and control parameters, and various other mechanisms of emergence and pattern formation appear in many different systems and are « substrate-independent » and universal. Recognizing this was as significant as the discovery of the principles themselves. This realization paved the way for the development of synergetics, a general and transdisciplinary theory and methodology of self-organization in complex systems. In the sense of Kuhn, synergetics could indeed be considered a « scientific paradigm » that is highly relevant for many disciplines concerned with pattern formation and pattern change on different time scales, in different magnitudes, and concerning various contents. According to the « non-statement view » by Sneed and Stegmüller, synergetics would be a structural theory whose theoretical core could be « enriched » by successful applications in different disciplines.

For Hermann Haken, this innovative path began with work on solid-state physics and the quantum theory of lasers, which he had developed in the 1960s together with his colleagues Wolfgang Weidlich and Hannes Risken (published in the book « Laser Theory, » 1970). Alongside his student Robert Graham, he was able to interpret the transition to highly coherent laser light as a phase transition. The mathematical brilliance of this theory extended to many other applications and elaborations, which distinguished synergetics from concepts that typically used terms like « self-organization » only metaphorically. Soon, other applications followed, for example, in flow theory, in the field of pattern formation in biological structures, in chemistry and physiology, in motor control and movement sciences (such as the famous Haken-Kelso-Schöner model of finger movement), in computer science, and in neuroscience. (For those interested in this developmental path of synergetics, refer to the book by B. Kröger (2013): « Hermann Haken and the Early Years of Synergetics. » Berlin: Logos-Verlag.) In the field of neuroscience, synergetics was further developed by talented former doctoral students like Peter Tass and Viktor Jirsa, as the brain was successfully interpreted as a complex, nonlinear, multi-particle system (i.e., in synergetics, always mathematically modeled), and pattern formation became the foundation for understanding both physiological and pathological functioning, such as in epilepsy, Parkinson’s disease, or tinnitus. Synergetics now offers far-reaching therapeutic possibilities in these areas.

Synergetics is not only applicable in various disciplines but has also created a cross-disciplinary bond (transdisciplinarity) that offers concepts, methods, and terminologies for developing interdisciplinary solutions and counters the trend of disciplinary segregation.

For psychology, synergetics has been significant in various ways. On one hand, under the influence of the cognitive psychologist and Gestalt theorist Michael Stadler, a connection was made to one of the most important roots of psychology, Gestalt psychology. On the other hand, synergetics was broad enough to establish a school-spanning bio-psycho-social understanding of psychotherapy as the promotion of self-organization processes. These processes can now be captured in practice using the Synergetic Navigation System (SNS), which enables high-frequency self-assessments and third-party assessments with an app and analyzes them using available methods of nonlinear time series analysis, displaying them visually. The integrative and personalized approach based on this is referred to as Synergetic Process Management. Personally, it was a great joy and honor for me to co-author the comprehensive book « Synergetics in Psychology » with Hermann Haken (Hogrefe Publishing, 1st ed. 2006, 2nd ed. 2010). Many colleagues in psychology and related fields of science and application were professionally and personally inspired by Hermann Haken, including Jürgen Kriz, Wolfgang Tschacher, Ewald Brunner, and myself.

Not only are the theories and synergetics as a whole impressive, but Hermann Haken’s life achievements are equally remarkable. He was born on July 12, 1927, in Leipzig, and studied mathematics (PhD 1951) and physics at Martin Luther University Halle-Wittenberg and the University of Erlangen. After his habilitation at the University of Erlangen, he spent time in research positions in Great Britain and at Bell Laboratories (USA), where he experienced the development of laser technology firsthand. In 1961, he was appointed to the chair of theoretical physics at the Technical University (later University) of Stuttgart, where he taught and conducted research until his retirement in 1995. Besides his research achievements, Professor Haken was also appreciated and loved as a teacher and lecturer. He declined possible appointments (e.g., a call to Munich) — partly due to interventions from his students, who were very fond of him — and remained loyal to his university in Stuttgart until his retirement. I had the opportunity to visit him several times there (at Pfaffenwaldring) and engage in both inspiring and motivating conversations. Professor Haken supervised numerous doctoral students, many of whom are now famous professors and institute directors themselves.

Professor Haken’s achievements as an author, editor, and organizer are also worth highlighting. He wrote numerous textbooks that became standard works in physics (e.g., Haken/Wolf: « Textbook on Atomic and Quantum Physics. » Berlin: Springer, multiple editions) and have been translated into various languages. In addition to the Western world, synergetics was also met with great interest in the East; several books, for example, have been translated into Japanese and Russian. In total, besides countless contributions to German and international journals, he authored over 20 books and monographs, covering topics such as atomic and molecular physics, brain dynamics, information theory, and, of course, synergetics, all of which were well-prepared didactically and mathematically excellent. He also wrote several popular science books, such as « The Secrets of Nature’s Success » and « The Secrets of Perception, » together with his daughter Maria Haken-Krell. Equally well-known and impressive is the « Springer Series in Synergetics, » which he founded in 1977 and which comprises over 140 volumes (monographs, edited volumes, and conference proceedings), demonstrating the interdisciplinary breadth of synergetics. By 1990, there was already a volume on « Synergetics of Cognition » (Haken/Stadler), and in 1992, one on « Synergetics in Clinical Psychology » (Tschacher/Schiepek/Brunner).

Personal exchanges and scientific collaborations were also characteristic of his work style. Among other things, he spent research and lecture stays in Kyoto, Paris, Strasbourg, Italy, and the USA and frequently hosted renowned scientists at his institute. He also organized numerous conferences, such as the legendary conference series at Schloss Elmau, and participated as a « spiritus rector » in many conferences and meetings, such as the Autumn Academies founded at the University of Bamberg, later the Summer Academies in Seeon Monastery.

The honors bestowed upon Professor Haken are almost innumerable. He received honorary doctorates from the Universities of Essen, Regensburg, Madrid, TU Munich, and Florida Atlantic University. Among other awards, he received the Max Born Prize (1976) and the Max Planck Medal (1990) from the German Physical Society, the Albert A. Michelson Medal of the Franklin Institute, Philadelphia (1981), the Honda Prize for Fundamental Research from the Honda Foundation, Tokyo (1992), the Lorenz Oken Medal from the Society of German Scientists and Physicians (1994), and honorary membership in the German Physical Society. He was a member of several scientific academies, including the German Academy of Sciences (Leopoldina), the Heidelberg Academy of Sciences, and the European Academy of Sciences and Arts, and since 1984, a member of the « Order Pour le Mérite, » which includes only about 80 scientists and artists from Germany and around the world and is one of the highest honors in the Federal Republic of Germany. He was also a recipient of the Federal Cross of Merit with Star.

With Hermann Haken, we have lost a great scientist, teacher, and mentor, and many of us have lost a wonderful colleague and friend. However, more significant than this loss is what we have gained through him — his perspectives, inspiration, and fascinating ideas will continue to have an impact, and collegial cooperation in his spirit will endure for a long time to come.

*Günter Schiepek*

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