## Mitchell Feigenbaum: the interviewer

In [M Feigenbaum, Reflections of the Polish masters - an interview with Stanislaw Ulam and Mark Kac,

*Wiadom. Mat.***30**(1) (1993), 93-114]**Mitchell Feigenbaum**conducts a fascinating interview. However, the article also contains a description of Feigenbaum who is half-Polish, unlike the two whom he interviews who are Poles. Here is the description of Feigenbaum written in 1984:-Mitchell Feigenbaum, mathematical physicist and key contributor to the theory of chaos, proudly acknowledges that he, too, is half Polish. Born in New York City, he was, from an early age, deeply interested in understanding nature's puzzles. And, like his Polish seniors, Kac and Ulam, he has an abiding interest in both the nature of human experience and the nature of the human brain. One of his distant hopes is that his new approach to chaotic phenomena may provide a clue on how to model the complex processes of the brain.

But speculation and fanciful notions notwithstanding, his work reflects his profound understanding of what makes for real progress rather than mere amusement in mathematical science. Briefly, he discovered a universal quantitative solution characterized by specific measurable constants that describes the crossover from simple to chaotic behaviors in many complex systems.

With the first experimental verification of these predictions for the onset of turbulence in fluids, it became clear that a new methodology had become available to treat previously intractable problems, The idea of the method is that a very low dimensional discrete nonlinear model that incorporates only the most basic qualitative features can, because of universality, correctly predict the precise quantitative details of a highly complex system. One is therefore directed to take very seriously - and not merely as a mathematically suggestive toy - the study of what had otherwise appeared to be a naive and oversimplified model. Indeed, these investigations of low dimensional discrete systems have by now blossomed into a large experimental and theoretical subdiscipline.

Thus, Feigenbaum is regarded as one of the founders of the modern subject of chaos and has several new mathematical/physical constants named after him. In 1980 he received a Los Alamos Distinguished Performance Award for this seminal work. A staff member at Los Alamos since 1974 and a Laboratory Fellow since 1981, he is currently on leave of absence as a Professor of Physics at Cornell University.