molecular processes that determine life, limits would be encountered
that could not be negotiated using the currently known frameworks
of chemistry and physics. An expansion of our description of nature
might be required to describe life at the molecular level, just as an
expansion of our description of nature was required to describe the
structure and properties of atoms. It could turn out to be a very excit-
ing time for biology, just as it had very recently been for physics!
In the audience at Bohr’s lecture was Max Delbriick (1906-1981), a
young theoretical physicist from Berlin who had been spending time
at Bohr’s Copenhagen institute since the previous year. Bohr’s notion
that one might encounter fundamental impasses in attempting to un-
derstand life in physical terms fascinated Delbriick and inspired him
to begin to think about how to investigate the molecular infrastruc-
ture of living organisms.
Figure 4.2 shows physicists at a gathering in Bohr’s institute in
- In the front row, left to right, are Niels Bohr, Paul Dirac, Werner
Heisenberg, Paul Ehrenfest, Max Delbriick, and Lise Meitner. Between
1932 and 1937 Delbriick worked as an assistant to Lise Meitner
(1878-1968) in Berlin, applying concepts and methods from math-
ematical physics to the investigation of radioactive decay and what
would by 1939 be appreciated as atomic fission. On the side, he began
learning about biology.
In 1935, Delbriick collaborated with a geneticist and a radiation
experimentalist to publish his first work in biology, a technical mono-
graph titled, in English translation, “On the nature of gene mutation
and gene structure.” In this paper, Delbriick and his collaborators
proposed that genes were likely to be large molecules, the atomic
configurations of which could be rearranged when impacted by high-
energy electromagnetic radiation, such as x-rays. Although the pub-
lication remained relatively obscure, the authors distributed copies