The University of Cologne and the international community of researchers in foundations of physics mourn the loss of Peter Mittelstaedt, who passed away on November 21, 2014, after a short period of illness. Peter Mittelstaedt held a chair in theoretical physics at the University of Cologne from 1965 until his retirement in 1995. In addition to his engagement as a scientist and academic teacher he was elected first as Dean of the Faculty of Science and then Rector of the University (...) of Cologne . Subsequently he served as Prorector and Prorector for Research . He was an elected member of l’Académie Internationale de Philosophie des Sciences and founding member and president of the International Quantum Structures Association .Peter Mittelstaedt was born in Leipzig on November 24, 1929. In his childhood home he may already have witnessed the spirit of philosophical discourse about the world-picture of modern physics. For Werner Heis .. (shrink)