In Intermediate Physics for Medicine and Biology, Russ Hobbie and I analyze the role physics plays in the biological sciences. What is that role, and how did it begin? Insight can be found in Horace Freeland Judson’s classic book The Eighth Day of Creation: The Makers of the Revolution in Biology. The development of molecular biology occurred in the mid-twentieth century and was spurred in part by immigrant physicists escaping central Europe before the start of World War II. Judson describes this intellectual exodus from physics to biology.
The mass intellectual emigration from continental Europe in the 1930s, which so stimulated physical science in the United States and England, also had profound consequences for biology, even though the men involved were fewer and younger, with their reputations still to make. They included [Max] Perutz, who left Austria for England in 1936, and [Erwin] Chargaff, also an Austrian, who emigrated to the United States in 1934. A less direct influence was the distinguished and passionately intelligent Hungarian physicist Leo Szilard, who in the 1930s had been the first to envision the possibility that sustained nuclear fission, a chain reaction, would work and cause an explosion, and the first to urge that the United States should try to make an atomic bomb. Szilard wrote the letter about the idea that [Albert] Einstein signed and that was read to [President Franklin] Roosevelt in 1939. Szilard worked on the atomic project at the University of Chicago through the war; afterwards, in reaction against the weapons and against the big-money, big-team physics he had been instrumental in creating, he turned to biology and also to campaigning within the international scientific community for disarmament-for example, through the Pugwash conferences, which he helped to found. In 1947, [University of Chicago chancellor Robert] Hutchins gave Szilard the physicist an appointment as professor of biology and sociology. In the early years of molecular biology, Szilard was an erratic if interesting experimenter and theorist, a cross-pollinator of ideas and an effective critic of others’ work, an intellectual and ethical inspiration to younger scientists.
The most important immigrant to biology, however, was Max Delbrück. Delbrück was German, born to the aristocracy of the intellect — his father was the professor of history and his uncle the professor of theology in the University of Berlin — and trained as a quantum physicist. His mind and style had been formed by Niels Bohr, the physicist, philosopher, poet, and incessant Socratic questioner who made Copenhagen one of the capital cities of science between the wars. Delbrücks ideas about the physical properties of the gene, in a youthful paper of 1935, had led [Austrian physicist Erwin] Schrödinger to write [the influential book] What Is Life? Delbrück was perhaps the earliest of the theoretical physicists who have crossed over to biology; Szilard, [Francis] Crick, Maurice Wilkins were others, while Linus Pauling, arriving at biology from a different tangent, was a physical chemist whose strength was founded in quantum mechanics. The move from physics has been the intellectual immigration that has mattered most to biology [my italics].
Each of us who has emigrated from physics to biology has followed in the footsteps of giants such as Szilard and Delbrück. We each follow our own individual path, but share a common bond. Physicists have played key roles in biology, and will continue to do so.