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
world'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
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 Gouttingen in 1925 under Richard
Courant's direction. He continued in Gouttingen as Courant's assistant for a while, and then he worked in Aachen for
a few years as assistant 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 parrtnership
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
- 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
Hermann Weyl, Courant, and John von Neumann; and by close collaborations with Hans Lewy and with Jim Stoker.
Friedrichs alternated periods of working on applied mathematical problems with working on more purely
mathematical questions. He was always interested in philosophy. In an age of specialization 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 studying 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 activities 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 people'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 professor 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
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.