These achievements were merit of his unique talent, combining a deep knowledge of physics with a rigorous mathematical approach.

Their theoretical description of the structure and symmetry of incommensurate crystals using higher dimensional superspace groups also included the quasicrystals that were discovered in 1982 by Dan Schechtman, who received the Nobel Prize in Chemistry in 2011.

He again showed his interest in a wide variety of topics by attending lectures in ethics, philosophy, music and sculpture.

After studying theoretical physics in Utrecht University Ted graduated under Leon van Hove with his doctoral dissertation ‘the classical limit of quantum mechanical diagram expansions’ and he was offered the opportunity to present it at an international conference in Utrecht on ‘Many-body Problems’.

No less than six Nobel laureates (Yang, Lee, Prigogine, Anderson, Cooper and Schrieffer) were in the audience for Ted’s first presentation, which led to his first publication as well: ’On the classical limit of the diagram expansion in quantum statistics’ by T.W.J.M.

After his doctoral exam in 1960 Ted worked for several years with professors Theo Ruijgrok, Tini Veltman, and John Tjon in Utrecht.

After his promotion Ted Janssen got a position in Nijmegen at the department of Theoretical Solid State Physics.

In the years that followed Ted taught many classes, including electrodynamics, classical mechanics, quantum mechanics, complex functions, crystallographic groups, group theory for physicists, chaos theory, soft modes and solid state physics.

Back in Nijmegen Ted was promoted to associate professor in 1972 and he continued working with Aloysio Janner and Li Ching Chen on space-time symmetry of electromagnetic fields and independently on PUA (projective unitary/anti-unitary) representations.

The award ceremony was followed by a symposium and the speakers were Aloysio Janner, Ted Janssen, Gervais Chapuis, Mike Glazer, Borje Johansson, Sander van Smaalen, Vaclav Petrcek and Reine Wallenberg.

Ted spent time as visiting lector or professor in Leuven (1969), Zürich (1971-1972), Dijon (1987), Paris, Orsay, Palaiseau (1992), Gif-sur-Yvette (1993), Grenoble (1986 and 1990), Marseille (2001), Nagoya (1992), Lausanne (2003), Beer Sheva (2003) en Sendai (2004-2005 and 2013).