Max Delbrück

Max Ludwig Henning Delbrück was born on September 4, 1906, in Berlin and grew up in Grunewald, a suburb of Berlin, the youngest of seven children.⁠[1][2]

His father, Hans Delbrück, was a professor of history at the University of Berlin and for many years editor of and political columnist for the Preussische Jahrbücher; his mother was a granddaughter of the chemist Justus von Liebig.⁠[3]

Grunewald was home to academic, professional and merchant families. Delbrück grew up through the hardships of the First World War and the postwar revolution, inflation and impoverishment; the physical chemist Karl Friedrich Bonhoeffer, eight years his senior, became his mentor and lifelong friend.⁠[3]

While at the Grunewald Gymnasium Delbrück developed an interest in astronomy. In 1924 he spent a semester at the University of Tübingen, then studied in Berlin and Bonn, and in the summer of 1926 settled in Göttingen, then the center of excitement in theoretical physics, where he turned to theoretical physics.⁠[2][3]

In 1930 he received his PhD from the University of Göttingen with a thesis on the lithium molecule (Li₂) suggested by Walter Heitler.⁠[2]

From 1929 to 1932 Delbrück did postdoctoral work in England, Denmark and Switzerland. Invited by John Lennard-Jones, he spent 18 months at the University of BristolUniversity of BristolThe University of Bristol is a research university in Bristol, England, United Kingdom. It began as University College, Bristol, which opened in 1876, became a university under a royal charter in 1909 and is a member of the Russell Group.Open the full entry; in the spring and summer of 1931 he studied with Niels Bohr in Copenhagen as a Rockefeller Fellow, collaborating with George Gamow on a nuclear physics project; he then spent six months with Wolfgang Pauli in Zurich before returning to Bristol for a further six months with Lennard-Jones.⁠[3][2]

Bohr’s ideas on complementarity led him toward biology.⁠[3]

In the autumn of 1932 Delbrück returned to Berlin as assistant to Lise Meitner at the Kaiser Wilhelm Institute for Chemistry, in effect serving as a theoretical physics consultant.⁠[2][3]

From about 1934 he took part in a private group of physicists and biologists that included N. W. Timofeeff-Ressovsky. In 1935 he published a paper on gene mutation and gene structure with Timofeeff-Ressovsky and K. G. Zimmer, which Erwin Schrödinger’s What Is Life? (1945) later popularized.⁠[3][2]

In 1937 Delbrück went to the United States on a second Rockefeller FoundationThe Rockefeller FoundationThe Rockefeller Foundation is a private philanthropic foundation headquartered in New York City. It was chartered by New York State legislation in 1913 with funding from Standard Oil founder John D. Rockefeller, with the mission “to promote the well-being of mankind throughout the world.” In its early years it funded global public health, medical education, and yellow fever vaccine research; in the mid-20th century it supported agricultural programs that came to be known as the “Green Revolution”; and in recent years it has focused its work on energy, health, food, and climate.Open the full entry fellowship, choosing the California Institute of Technology for its strength in Drosophila genetics. There he joined E. L. Ellis in phage research.⁠[3][2]

The fellowship ended in September 1939, and after the Second World War began he remained in the United States.⁠[3]

From 1940 to 1947 Delbrück was Instructor of Physics at Vanderbilt University in Nashville, Tennessee, and was later promoted to Associate Professor; half his time was devoted to biological research, with half his salary paid by the Rockefeller Foundation.⁠[2][3]

At the end of 1940 he met Salvador Luria.⁠[2]

On August 2, 1941, Delbrück married Mary Adeline (Manny) Bruce in Pasadena, California. They had four children: Jonathan (born 1947 in Nashville), Nicola (born 1949 in Pasadena), Tobias (born 1960 in Pasadena) and Ludina (born 1962 in Cologne).⁠[2][3]

In 1943 Delbrück and Luria published a paper on bacterial mutation in Genetics (vol. 28), using statistical analysis to show that bacteria, like more complex organisms, change through mutations.⁠[2][1]

At the beginning of 1943 he invited Alfred Hershey to Nashville; Delbrück, Luria and Hershey formed the nucleus of the “Phage Group.”⁠[2]

In 1945 Delbrück organized the first Phage Course at Cold Spring Harbor, the first of 26 successive annual courses, and was principal instructor for the first three. The Phage Group’s geographic center was the Biological Laboratory at Cold Spring Harbor. The first Phage Meeting was held in Nashville in 1947; from the fourth meeting in 1950 the meetings took place at Cold Spring Harbor.⁠[2][4]

In 1946 Delbrück discovered an unexpected genetic interaction between viruses infecting the same cell; Hershey later showed that this was genetic recombination.⁠[4]

On December 11, 1946, Delbrück received the offer of a Chair of Biology at the California Institute of Technology; he accepted on December 27.⁠[2]

In the early 1950s his research shifted from molecular genetics to sensory physiology, using the sporangiophore of Phycomyces as a model system for stimulus transduction.⁠[3]

Delbrück set up the Institut für Genetik der Universität Köln. The institute was approved in 1959, its staff moved in during the summer of 1961, and it was formally dedicated on June 22, 1962, when Niels Bohr gave the principal address, “Light and Life – Revisited,” his last formal lecture.⁠[3][2]

He agreed to serve in Cologne for two years only, on leave of absence from the California Institute of Technology, and became an honorary professor on leaving in 1963. From 1964 he resumed experimental work on Phycomyces together with related theoretical studies.⁠[2][3]

In 1969 Delbrück, of the California Institute of Technology, shared the Nobel Prize in Physiology or Medicine equally with Salvador Luria and Alfred Hershey “for their discoveries concerning the replication mechanism and the genetic structure of viruses.”⁠[1]

On December 10, 1969, Delbrück delivered his Nobel Lecture, “A Physicist’s Renewed Look at Biology – Twenty Years Later.”⁠[5]

In 1977, on reaching retirement age, Delbrück was appointed by the California Institute of Technology trustees to the special position of Board of Trustees Professor of Biology, Emeritus. Early in 1978 he was diagnosed with multiple myeloma.⁠[2]

Delbrück died in Pasadena, California, on March 9, 1981.⁠[1]

Delbrück and Luria introduced genetic concepts and rigorous quantitative methods into phage research; between 1940 and 1945 they established the main outlines of phage multiplication and criteria for distinguishing mutation from other modifications. He also made theoretical contributions to understanding how nucleic acids replicate.⁠[4]

His 1933 result on the scattering of gamma rays was sound but did not apply to the case he was studying; some 20 years later Hans Albrecht BetheHans Albrecht BetheHans Albrecht Bethe (1906–2005) was a German-born American theoretical physicist who joined Cornell University in 1935, headed the theoretical division at Los Alamos during the Second World War and received the 1967 Nobel Prize in Physics for his work on nuclear reactions and the energy production of stars.Open the full entry confirmed the effect and named it “Delbrück scattering.”⁠[2]

Delbrück was elected to the US National Academy of Sciences in 1949, the American Academy of Arts and Sciences in 1959, the Royal Danish Academy in 1960 and the Leopoldina in 1963; he received the National Academy of Sciences’ Kimber Medal for Genetics in 1964, the Leopoldina’s Gregor Mendel Medal and Foreign Membership of the Royal Society in 1967, Columbia UniversityColumbia UniversityColumbia University, formally Columbia University in the City of New York, is a private research university in New York City and a member of the Ivy League. Founded in 1754 by royal charter from King George II as King's College, it is the oldest institution of higher education in New York State and the fifth oldest in the United States. It was renamed Columbia College in 1784 and adopted the university name and moved to Manhattan's Morningside Heights in 1896. It has 17 schools and four affiliated colleges, with 35,978 students enrolled in fall 2025. Legal scholar Jennifer L. Mnookin became president on July 1, 2026.Open the full entry’s Gross-Horwitz Prize in 1969, and became a foreign associate of the Académie des Sciences in Paris in 1979.⁠[2]

The University of Bristol lists Delbrück on its “Nobel Prizes and Fellowships” page among the Nobel laureates connected with the university, recording him as a research worker there in 1930–1932.⁠[6]