Max Delbrück

Max Ludwig Henning Delbrück (September 4, 1906 – March 9, 1981) was a German-American biophysicist and Nobel laureate.
Delbrück was one of the most influential people in the movement of physical scientists into biology during the 20th century.
Delbrück's big idea was to explore genetics by means of the bacteriophage viruses which infect bacteria. This was important in the early development of molecular biology.
Biography.
Delbrück was born in Berlin, German Empire. Trained as a physicist, he got his Ph.D. in 1930. he traveled through England, Denmark, and Switzerland. He met Wolfgang Pauli and Niels Bohr, who got him interested in biology.
In 1937, he moved to the United States to pursue his interests in biology, taking up research in the Biology Division at Caltech on genetics of the fruit fly "Drosophila melanogaster". While at Caltech Delbrück became acquainted with bacteria and their viruses (bacteriophage or 'phage').
Delbrück remained in the US during World War II, teaching physics at Vanderbilt University in Nashville while pursuing his genetic research. In 1942, he and Salvador Luria of Indiana University demonstrated that bacterial resistance to virus infection is caused by random mutation and not adaptive change. This research, known as the Luria-Delbrück experiment, was also significant for its use of mathematics to make quantitative predictions for the results to be expected from alternative models. For that work, they were awarded the Nobel Prize in Physiology or Medicine in 1969, sharing it with Alfred Hershey.
During the 1940s Delbrück developed a course in bacteriophage genetics at the Cold Spring Harbor Laboratory to encourage interest in the field. In 1947, Delbrück returned to Caltech as a professor of biology where he remained until 1977.