Kurt Otto Friedrichs

Friedrichs was born in Kiel, Schleswig-Holstein on September 28, 1901. His family soon moved to Düsseldorf, where he grew up. He attended several different universities in Germany studying the philosophical works of Heidegger and Husserl, but finally decided that mathematics was his real calling. During the 1920s, Friedrichs pursued this field in Göttingen, which had a renowned Mathematical Institute under the direction of Richard Courant. Courant became a close colleague and lifelong friend of Friedrichs.

In 1931, Friedrichs became a full professor of mathematics at the Technische Hochschule in Braunschweig. In early February 1933, a few days after Hitler became the Chancellor of Germany, Friedrichs met and immediately fell in love with a young Jewish student, Nellie Bruell. Their relationship became increasingly challenging and difficult because of the anti-Semitic Nuremberg Laws of Hitler's government. In 1937, both Friedrichs and Nellie Bruell managed to emigrate separately to New York City where they finally married. Their long and very happy marriage produced five children.[http://www.friedrichs.us/history-KOF-life-by-C-Reid.html Life of K. O. Friedrichs]

Courant had left Germany in 1933 and had founded an institute for graduate studies in mathematics at New York University. Friedrichs joined him when he arrived in 1937 and remained there for forty years. He was instrumental in the development of the Courant Institute of Mathematical Sciences, which eventually became one of the most distinguished research institutes for applied mathematics in the world. Friedrichs died in New Rochelle, New York on December 31, 1982.

Friedrichs's greatest contribution to applied mathematics was his work on partial differential equations. He also did major research and wrote many books and papers on existence theory, numerical methods, differential operators in Hilbert space, non-linear buckling of plates, flows past wings, solitary waves, shock waves, combustion, magneto-fluid dynamical shock waves, relativistic flows, quantum field theory, perturbation of the continuous spectrum, scattering theory, and symmetric hyperbolic equations. With Cartan,{{Citation

| last=Cartan

| first=Élie

| date=1923

| title= Sur les variétés à connexion affine et la théorie de la relativité généralisée (Première partie)

| journal= Annales Scientifiques de l'École Normale Supérieure

| volume=40

| page=325

|author-link=Élie Cartan

| url=http://archive.numdam.org/article/ASENS_1923_3_40__325_0.pdf

| doi=10.24033/asens.751

| doi-access=free

}}

{{Citation

| last=Cartan

| first=Élie

| date=1924

| journal= Annales Scientifiques de l'École Normale Supérieure

| volume=41

| title= Sur les variétés à connexion affine, et la théorie de la relativité généralisée (Première partie) (Suite)

| url=http://archive.numdam.org/article/ASENS_1924_3_41__1_0.pdf

| page=1

| doi=10.24033/asens.753

| doi-access=free

}} Friedrichs{{Citation

| last=Friedrichs

| first=K. O.

| date=1927

| journal=Mathematische Annalen

| volume=98

| title=Eine Invariante Formulierung des Newtonschen Gravitationsgesetzes und der Grenzüberganges vom Einsteinschen zum Newtonschen Gesetz

| pages=566–575

| doi=10.1007/bf01451608

| s2cid=121571333

}} gave a "geometrized" formulation of Newtonian gravitation theory—also known

as “Newton–Cartan theory”— and later developed by Dautcourt, Dixon, Dombrowski and Horneffer, Ehlers, Havas, Künzle, Lottermoser, Trautman, and others.

A member of the National Academy of Sciences since 1959, Friedrichs received many honorary degrees and awards for his work. There is a student prize named after Friedrichs at NYU. The American Mathematical Society selected him as the Josiah Willards Gibbs lecturer for 1954.[https://www.ams.org/meetings/lectures/meet-gibbs-lect Josiah Willard Gibbs Lectures]{{cite journal|author=Friedrichs, K. O.|title=Asymptotic phenomena in mathematical physics|journal= Bulletin of the American Mathematical Society|year=1955|volume=61|issue=6|pages=485–504|mr=0074614|doi=10.1090/s0002-9904-1955-09976-2|doi-access=free}} In November 1977, Friedrichs received the National Medal of Science from President Jimmy Carter "for bringing the powers of modern mathematics to bear on problems in physics, fluid dynamics, and elasticity."

• R. von Mises and K. O. Friedrichs, Fluid Dynamics, Springer-Verlag (1971).
• K. O. Friedrichs, Perturbation of Spectra in Hilbert Space, American Mathematical Society (1965).
• K. O. Friedrichs, Mathematical aspects of the quantum theory of fields, Interscience (1953).{{cite journal|author=Segal, I. E.|author-link=Irving Segal|title= Book Review: Mathematical aspects of the quantum theory of fields|journal= Bulletin of the American Mathematical Society|year=1954|volume=60|issue=6|pages=575–576|url=https://www.ams.org/journals/bull/1954-60-06/S0002-9904-1954-09861-0/S0002-9904-1954-09861-0.pdf|doi=10.1090/s0002-9904-1954-09861-0}}
• K. O. Friedrichs, Spectral Theory of Operators in Hilbert Space, Springer-Verlag (1981).
• {{Citation

| last = Friedrichs

| first = Kurt Otto

| author-link = Kurt Otto Friedrichs

| editor-last = Morawetz

| editor-first = Cathleen S.

| editor-link = Cathleen Synge Morawetz

| title = Selecta

| place = Boston–Basel–Stuttgart

| publisher = Birkhäuser Verlag

| year = 1986

| series = Contemporary Mathematicians

| url = https://books.google.com/books?id=l1Z_yHVjor4C&q=Kurt+Otto+Friedrichs+selecta&pg=PP1

| isbn = 0-8176-3270-0}}. A selection from Friedrichs' works with a biography and commentaries of David Isaacson, Fritz John, Tosio Kato, Peter Lax, Louis Nirenberg, Wolfgang Wasow, Harold Weitzner.

• Singular perturbation

{{reflist}}

• {{MathGenealogy |id=22260}}
• {{MacTutor|id=Friedrichs|title=Kurt Otto Friedrichs}}
• [http://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/friedrichs-kurt-otto.pdf National Academy of Sciences Biographical Memoir]
• {{DNB portal|118820265}}

{{Winners of the National Medal of Science|math-stat-comp}}

{{John von Neumann Lecturers}}

{{Authority control}}

{{DEFAULTSORT:Friedrichs, Kurt O.}}

Category:1901 births

Category:1982 deaths

Category:Scientists from Kiel

Category:Scientists from New Rochelle, New York

Category:20th-century German mathematicians

Category:20th-century American mathematicians

Category:National Medal of Science laureates

Category:Members of the United States National Academy of Sciences

Category:Partial differential equation theorists

Category:Operator theorists

Category:Courant Institute of Mathematical Sciences faculty

Category:Academic staff of the Technical University of Braunschweig

Category:Mathematicians from New York (state)

Category:Emigrants from Nazi Germany to the United States