Max Delbruck, Lisa Meitner, Niels Bohr, and the Nazis

 The following set of tales primarily concerns the crossing of paths of three rather exceptional individuals; Max Delbruck, Niels Bohr, and Lisa Meitner. What’s more, other heavy hitters of 20^th century science and statecraft figure in these vignettes, which also happen to play out in Europe and the United States on the eve of, and during the Second World War.

Since this site is first and foremost an anthology of anecdotes related to virology, Max Delbruck is our focus here. With that in mind, the background is as follows. In the middle 1930s, interest in virology was for the most part medical and agricultural. Essentially all that was known at the time about viruses was that they are smaller than bacteria, that they can replicate only within suitable host cells, and that they are comprised only of nucleic acid and protein. Moreover, recall that nothing was yet known about the chemical nature of genes or how they might be replicated. The structure of DNA was not yet known, and most biologists of the day would have bet that genes consist not of DNA, but of protein. As one might imagine, attempts to account for how protein might be replicated led to rather unsatisfactory models, causing some physicists and chemists of the day to believe that living matter might be governed by as yet unknown physical laws.

At that time, a rather atypical group of investigators, many of whom had little or no knowledge of traditional genetics, biochemistry, or even biology in general, sought to understand the nature of genes. Many were physicists by background and, interestingly, they were primarily motivated by the notion that the study of genes might reveal previously unknown other laws of physics. Important to our story, several of these individuals recognized that since viruses are simple enough to be crystallized, and are comprised only of nucleic acid and protein, yet are capable of replication, viruses might be the ideal focus of their research into the nature of genes. The interest of this odd group of investigators in genes, and their focus on viruses, would lead to discoveries of singular overwhelming importance, not only with regard to viruses, but for biology in general. Indeed, their research in the 1930’s and 1940’s eventually led to the creation of the science known as molecular biology, a high point of which was the discovery of the structure of DNA by Watson and Crick in 1953.

Max Delbruck was perhaps the key player in this atypical group of scientists, which also included Salvatore Luria and Alfred Hershey. Together, these three individuals would comprise the original “phage group.” [Phages, short for bacteriophages, are viruses that replicate in bacterial cells.] Incidentally, James Watson was Luria’s first graduate student. Watson decided to do his doctoral research in Luria’s laboratory, at Indiana University, because he knew that Luria and Delbruck had done phage experiments together and were close friends.² Watson shared a bench with Renato Dulbecco, another future Nobel laureate (and another story), in Luria’s lab.

Delbruck originally trained as a physicist in Germany during the 1920s, studying quantum mechanics under the guidance of Max Born. Moreover, he interacted with other great physicists of the day, including Wolfgang Pauli, Albert Einstein, and Erwin Schroedinger. In 1931 Delbruck went to Copenhagen for postdoctoral studies with Niels Bohr, and it was actually Bohr who aroused Delbruck’s interest in biology¹. Indeed, Niels Bohr was the major scientific influence in Delbruck’s life.

At this point, we might say a word or two more about Bohr, the great Danish physicist who made exceptionally important contributions to the understanding of atomic structure and quantum mechanics. Indeed, Bohr is regarded by many as Einstein’s only intellectual equal. At a scientific conference, when Einstein famously attacked the probabilistic nature of quantum physics, saying “God does not play dice with the universe,” Bohr famously replied, “Einstein, stop telling God what to do.”

Delbruck came back to Germany in 1932 to work as an assistant to Lise Meitner at the University of Berlin, where she had a key research program in nuclear physics. Interestingly, Delbruck’s move to Meither’s lab was largely motivated by his desire to be near to the Kaiser Wilhelm Institutes (today known as the Max Planck Institute for Medical Research); then world-renowned for its biological research.

Delbruck was not Jewish. Even so, in 1937, with the Nazis in power, Germany became intolerable for him, and so he left Meitner’s laboratory, settling in the United States, where he accepted a teaching position at  the California Institute of Technology and, later, at Vanderbilt University.

Meitner was Jewish. However, she chose to remain in Germany, protected by her Austrian citizenship. She continued to focus on her work, while other eminent Jewish scientists, including her nephew Otto Frisch, and Leo Szilard were forced out of their positions and emigrated, if fortunate enough to be able to do so.

In 1940, Delbruck, together with Salvatore Luria and, eventually, Alfred Hershey, formed the “Phage Group,” as noted above, and did their first experiments at the Cold Spring Harbor Laboratory on Long Island, NY. Importantly, the slowly growing Phage Group comprised the first investigators to carry out quantitative experiments on the nature of viruses and their replication. And, as noted above, they were instrumental in the development of the new science of molecular biology.

Returning to Lisa Meitner, shortly after Delbruck left Germany, Meitner went on to discover nuclear fission. Meitner was also the first scientist to recognize that Einstein’s famous equation, E = mc², explained the source of the tremendous energy released in nuclear fission, as generated by the conversion of mass into energy; an idea actually inspired by a letter to her from Bohr. She and Leo Szilard were also the first (apparently independently) to recognize the possibility for a chain reaction; all necessary prerequisites for the making of an atomic bomb. These accomplishments are particularly intriguing because Meitner, as a Jew, was by then a non-person in Nazi Germany.

After the Anschluss (the annexation of Austria by Nazi Germany in 1938), Meitner’s situation in Germany became desperate. So, she fled Germany for safety in Holland, thanks to the efforts of Dutch physicists who persuaded their government to admit her on her Austrian passport that was no longer valid. In fact, Meitner was lucky to escape from Germany, since Kurt Hess, a chemist and an ardent Nazi, informed the Nazis of her imminent intent to flee. Later, in 1946, she acknowledged, “It was not only stupid but also very wrong that I did not leave (Germany) at once.”

Niels Bohr once again plays a role in our tale, since he found a laboratory in Sweden where Meitner might continue her work, and also secured funding for her from the Nobel Foundation. What’s more, Bohr helped to rescue numerous other refugees from the Nazis, including Felix Bloch, Otto Frisch, Edward Teller, and Victor Weisskopf. Recalling that Frisch was Meitner’s nephew, he and his aunt, together, were the first to articulate a theory of how the nucleus of an atom could be split into smaller parts. And, it was Frisch who named the process “nuclear fission.”

In 1943, having a Jewish mother and learning of his imminent arrest by the Nazis in occupied Denmark, Bohr, aided by the Danish resistance, fled by sea to neutral Sweden. The very day after Bohr arrived in Sweden, he persuaded the King, Gustav V, to give refuge to all of Denmark’s 8,000 Jews. Shortly afterwards, Swedish radio broadcast that       Sweden was offering asylum to the Danish Jews, and their mass rescue then successfully proceeded.

Even in Sweden, Bohr may not have been safe from German agents, who were rumored to be out to assassinate him there. This led to his harrowing escape to Scotland. Bohr was spirited away in the un-pressurized empty bomb rack of an unarmed Royal Air Force Mosquito Bomber. Not hearing the order to switch on his oxygen, he passed out at high altitude. The pilot suspected this and descended to a lower altitude for the remainder of the flight, thereby saving Bohr’s life.

Bohr spent the last 2 years of the war in England and America, where he was associated with the Atomic Energy Project, and then became one of the first and most prescient arms control advocates. Bohr believed it would be a great tragedy if a nation were to deploy its nuclear bomb against a nation that did not have the bomb. On the other hand, he believed that if all nations shared atomic bomb technology, then war might become unthinkable. Thus, he believed that sharing bomb technology with the Russians would prevent an otherwise inevitable breakdown in trust between the wartime allies, as well as a destabilizing post-war arms race. Bohr was prestigious enough to obtain audiences with both Roosevelt and Churchill. However, the politicians saw only the military implications of the atomic bomb. To them, it was simply a bigger and better bomb than all the others. What’s more, Churchill wondered if Bohr might be a Russian agent. Incidentally, Meitner refused an offer to work on the bomb project at Los Alamos, stating “I will have nothing to do with a bomb!”

Getting back to Delbruck, even while he was working with Meitner, his interest was actually on developing quantum mechanical models of genes, an approach inspired by Schroedinger. Afterwards, Delbruck (jokingly?) took indirect credit for Meitner’s discovery of nuclear fission, saying that his waning interest in physics was holding back Meitner’s group, and thus, his leaving enabled the discovery to happen.

Delbruck shared the 1969 Nobel Prize in Physiology or Medicine with Luria and Hershey, for their work on the genetic structure and replication of viruses.

Bearing in mind the times and places of the above episodes, we might add a few more words about Luria, an Italian Jew who studied medicine at the University of Turin (where, incidentally, he first met Renato Dulbecco, who eventually won a Nobel for his foray into animal viruses; work which he began in Delbruck’s laboratory at Cal Tech, and the subject of another story). In 1937, while still in Italy, Luria was awarded a fellowship that he intended to use to work with Delbruck in the United States. However, Mussolini’s fascist Italian regime banned Jews from academic research fellowships. So, having no support, Luria left Italy for France in 1938. Then, in 1940, as German armies invaded France, Luria emigrated to the United States. In New York, physicist, Nobel laureate, and fellow Italian émigré, Enrico Fermi, helped Luria obtain a Rockefeller Foundation fellowship for use at Columbia University. [Fermi, himself, left Italy in 1938 to escape new Italian ‘racial’ laws that affected his Jewish wife Laura. In the United States, with Leo Szilard, he developed the first nuclear reactor.] Luria soon met Delbruck, and they began their collaborative experiments at the Cold Spring Harbor Laboratory on Long Island, NY. When Hershey later joined them, he described the threesome as “two enemy aliens and a social misfit.” Technically, Delbruck and Luria indeed were enemy aliens.

In contrast to Bohr and Delbruck, Meitner was never recognized by the Nobel Committee for her accomplishments. Instead, Meitner’s collaborator, German chemist Otto Hahn, was awarded the 1944 Nobel Prize in Chemistry (actually awarded in 1945) for the discovery of nuclear fission. The reasons for the slight to Meitner may have included her scientific and actual exile; perhaps causing the Nobel Committee to not appreciate her key part in the work. What’s more, Hahn and others may have intentionally downplayed her role. And, while Meitner was bitterly critical of Hahn and other German scientists for not speaking out against Hitler’s crimes, she and Hahn apparently remained lifelong friends. Earlier, when Meitner left Germany, she was virtually penniless. Otto Hahn gave Meitner a diamond ring that he inherited from his mother, for Meitner to use to bribe border guards if necessary. Meitner did not need to use the ring in her escape. It was later worn by her nephew’s wife.

Incidentally, Delbruck’s brother Justus, his sister Emmi, and two brothers-in-law were active in the German resistance against the Nazi regime. The three men were executed for their involvement in the 1944 plot to assassinate Hitler.

Delbruck influenced a whole generation of molecular biologists, both at Cal Tech and at Cold Spring Harbor, where, together with Luria, he established a summer phage course in 1945 that ran there for the next 26 consecutive years. The course did not require any previous preparation and those enrolled ranged from beginning graduate students to already eminent professors, all working side-by-side in the lab. One early taker was the brilliant physicist Leo Szilard. In 1939, after emigrating to the United States, Szilard wrote the famous letter to Franklin Roosevelt, which he convinced Albert Einstein [a German Jew who was visiting the United States when Hitler came to power in 1933 and did not go back to Germany] to sign, that resulted in the Manhattan Project and creation of the atomic bomb.  Working on the Manhattan Project with Enrico Fermi, they together built the first nuclear reactor at the University of Chicago. Incidentally, in 1930, Szilard and Lisa Meitner taught a seminar together in Berlin on nuclear physics and chemistry. And, in 1933, Szilard and Lisa Meitner were the first to conceive of a nuclear chain reaction, as noted above.

Aaron Novick, who eventually became a major molecular biologist, was a budding physicist in 1943, working on the Atomic Energy Project under Szilard at the University of Chicago. He relates how his transformation to a biologist came about, as follows. “One Spring evening in 1947, as we were leaving a meeting of the Atomic Scientists of Chicago, Szilard approached me and asked whether I would care to join him in an adventure into biology. Despite his caution to think his proposition over carefully, I accepted immediately… [My note: Szilárd’s scientific interests switched to molecular biology because of his revulsion over the use of atomic weapons.]…Szilard proposed that we get started in Biology by taking the Cold Spring Harbor phage course that had been recently started by Max Delbruck…It was evident to me that Szilard regarded Delbruck highly. Usually Szillard listened to people only as long as they had something to say that interested him and made sense. This meant that he often turned away in the middle of a conversation. But whenever Delbruck was talking, he stayed to listen.”³

By 1950, Delbruck’s interests began to turn from phage and genes to sensory physiology. Although the major breakthroughs of molecular biology (e.g., the structure of DNA, messenger RNA and the mechanism of protein synthesis, the genetic code) were yet to come, Delbruck was by then confident that biological self replication would be understood without the need to invoke new natural laws. So, he was ready to delve into a new scientific frontier. Nevertheless, Delbruck continued to be a major influence on molecular biology via the researchers who cut their teeth in the Cold Spring Harbor Phage Course or at Cal Tech.

I find these related anecdotes to be exceptionally intriguing. A fantasy is that I might one day participate in the creation of a screen play based upon them.

1. A Physicist Looks at Biology; Max Delbruck’s chapter in Phage and the Origins of Molecular Biology, J. Cairns, G.S. Stent, and J.D. Watson [eds.] Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1966.  Note that this essay was written by Delbruck in 1949, 4 years before the structure of DNA had been solved. Thus, it reveals Delbruck’s seminal thinking regarding the possibility of living systems being accounted for by as yet unknown laws of physics, and his indebtedness to Niels Bohr.
2. Growing Up in the Phage Group; James Watson’s chapter in Phage and the Origins of Molecular Biology, J. Cairns, G.S. Stent, and J.D. Watson [eds.] Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1966.
3. 3.      Phenotypic Mixing; Aaron Novick’s chapter in Phage and the Origins of Molecular Biology, J. Cairns, G.S. Stent, and J.D. Watson [eds.] Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1966. 

Related articles

• Historical Physicist Halloween Costumes [Uncertain Principles] (scienceblogs.com)
• Hipster goalies – Niels & Harold Bohr (nostanding13.wordpress.com)
• Prix Nobel: Cherchez la femme (Lise Meitner: Looking back at the woman who would not be a bomb) (jcdurbant.wordpress.com)