Max Delbruck, Biological Physicist

Niels Bohr's Times:
In Physics, Philosophy, and Polity,
by Abraham Pais.

Last week, I discussed the book Niels Bohr's Times: In Physics, Philosophy, and Polity by Abraham Pais. In particular, I summarized Pais’s view that Bohr played a key role in the development of nuclear medicine through his collaboration with Georg Charles von Hevesy. This week, I address another contribution of Bohr to biological physics through his influence on Max Delbruck.

Bohr had some unorthodox views about biology that were motivated by his idea of “complementarity” in quantum mechanics. Even Pais admits Bohr’s “thoughts on biology have not borne fruit,” which is a polite way to put it. But Delbruck, then a young physicist, wrote “I am perhaps the only one of his associates of those days who took [Bohr] so seriously that it determined [my] career, changing over into biology to find out whether indeed there was anything to this point of view.” Pais writes

Delbruck’s professional switch was Bohr’s greatest contribution to biology. In an obituary of Delbruck it has been written: “Odd though these views [expressed in Bohr’s lecture ‘Light and Life’] may seem to us now, in retrospect, this lecture confirmed Max’s decision to turn to biology... It is fair to say that with Max, Bohr found his most influential philosophical disciple outside the domain of physics, in that through Max, Bohr provided one of the intellectual fountainheads for the development of 20th century biology...”

[Delbruck’s] celebrated work on bacteriophages (viruses that infect bacteria) began after his move to Cal Tech in 1937, where he became professor of biology in 1946. It is worthy of note that, in the 1963 meeting at Copenhagen commemorating the 50th anniversary of Bohr’s first papers on atomic constitution, only one paper on complementarity was presented—by Delbruck, on biology. He received the Nobel Prize in 1969.

Delbruck, a German native, spent the years during World War II with the Department of Physics at Vanderbilt University in Nashville, Tennessee (where I later obtained my PhD). While at Vanderbilt, Delbruck collaborated with Salvadore Luria on an experiment using bacteriophages to show that mutations in viruses are random rather than directed events. The American Physical Society has named its prize in biological physics the Max Delbruck Prize for his work on genetics.

Why do I discuss Bohr, Hevesy and Delbruck in a blog about the 4th edition of Intermediate Physics for Medicine and Biology? Because they represent classic examples of how physics and physicists can make fundamental and lasting contributions to medicine and biology. And that is the whole point of the book.