Kurt O. Friedrichs was appointed to the faculty of New York University in 1937, and he retired in 1974. He died on
December 31, 1982 at the age of 81.
By absolute standards Friedrichs was a great mathematical scientist. His name would be on any short list of the worldâ
€™s leading mathematical analysts of the past fifty years. Beyond carrying out a successful mathematical analysis,
Friedrichs always sought a deep understanding of any problem in the con-text of the larger scientific issues. Pure
mathematicians, applied mathematicians, physicists, and engineers have all been profoundly influenced by him in their
work.
Friedrichs was a Fellow of the American Academy of Arts and Sciences, a Member of the National Academy of
Sciences, and received numerous other honors. The crowning recognition of his scientific achievements came in 1977
when he was awarded the National Medal of Science.
Friedrichs was born in Kiel, Germany, in 1901. He earned his Ph.D. degree at Göttingen in 1925 under Richard
Courant’s di-rection. He continued in Göttingen as Courant’s assistant for a while, and then he worked in
Aachen for a few years as assis-tant to the famous aerodynamicist, Theodore von Karman. In 1930 he was appointed to
a professorship in Braunschweig. But in 1937 Friedrichs left Germany because of his antipathy to the Nazi regime and his
decision to marry a Jewish woman.
Friedrichs came to New York to rejoin Courant, who had moved to New York University in 1934. In that same year,
1937, James J. Stoker also arrived at New York University. These three, Courant -- about ten years the senior -- and
Friedrichs and Stoker, were founders and intellectual leaders of what has now become the Courant Institute. Although
completely dissimilar in back-ground and personality, they maintained an enormously effective partnership for a quarter
century.
Of course it is impossible to describe briefly Friedrichs’ research to a general audience. All I can do is offer a
sampling of the names of the subjects that engaged him:
- partial differential equations (especially those representing the laws of physics and engineering)
- existence theory
- numerical methods
- differential operators in Hilbert space
- perturbation of the continuous spectrum
- scattering theory
- symmetric hyperbolic equations
- non-linear buckling of plates
- flows past wings
- solitary waves
- shock waves
- combustion
- magneto-fluid dynamical shock waves
- relativistic flows
- quantum field theory
You must realize that this incomplete list is long enough to sustain several careers.
In different ways Friedrichs’ attitude towards mathematics was strongly influenced by the work of three
mathematicians:
Hermann Weyl, Courant, and John von Neumann; and by close col-laborations with Hans Lewy and with Jim Stoker.
Friedrichs alternated periods of working on applied mathematical prob-lems with working on more purely mathematical
questions. He was always interested in philosophy. In an age of speciali-zation he was a generalist. And for him, method
and point of view counted as much as the result itself. He preferred crude methods to refined ones because they are more
powerful and have wider applicability. He took a special delight in study-ing inequalities.
Friedrichs’ strength was not so much a matter of technical skill as of conceptual daring. His brilliant mathematical re-
search came from thinking very deeply about fundamental issues.
His discoveries are those of a trail blazer. He got to the good problems before anyone else.
Friedrichs always wanted to have at least several hours every day to work on his mathematics. I once mentioned to him
how marvelous it was to be paid a salary to do mathematics. He replied that he always felt he was paid his salary for the
time he spent not doing mathematics. Friedrichs was completely involved in the development of the Courant Institute, and
he was always concerned about his students and teaching. He was careful to carve out a place that suited the balance of
acti-vities that nurtured his great talents. He was free from the vanity or ambition that might have led him into positions he
would not have enjoyed. However, Friedrichs did serve during the 1966-67 academic year as Director of the Courant
Institute. He wanted to provide a smooth transition from the leadership of his generation to the next. I was his assistant
director, and it was my great pleasure to work with him. He worried much more than I imagined he would about peopleâ
€™s feelings. It also struck me then how much he liked to have a philosophical principle for whatever he did, even if he
had to invent the principle after the action.
The attraction of his profound originality made Ph.D. students flock to him, and everyone used him as a consultant. His
classroom lectures were an experience that transformed many of his students. They were not polished performances. His
courses were tough because he was so original in the way he thought about mathematics. He taught many people to do
mathematics. He used to say that he believed the first part of a course should be confusion: that a student had to feel the
problem, to learn what would not work, to go into blind alleys; and that the second part of the course should be
deconfusion, clarification, and illumination. “Of course,� he said, “I sometimes don’t have time for the
second part.� Friedrichs also believed no pro-fessor should own a course. He liked to teach everything, and he
encouraged his colleagues to do the same. He was a Great Teacher, and so recognized by the University.
Friedrichs was a man driven all his life to carry out the possibilities he sensed in himself. I am sure he would deeply re-
sent any suggestion that he was happy or well-adjusted, but the fact is he worked successfully and serenely into his old
age without any trace of the bitterness that powerful men often feel when they are retired.
On the day we heard that he had died, we felt the pain one has when a very interesting conversation is interrupted.
