The film “Oppenheimer” has been in cinemas since last week. It tells the story of theoretical physicist Robert Oppenheimer, who led the Manhattan Project to develop the first atomic bomb during World War II. Oppenheimer, who died in 1967, is known as a charismatic leader, articulate intellectual and victim of the Red Fear. In 1954 he lost his security clearance, partly because of his previous contacts with suspected communists. Physicist and historian David C. Cassidy has written numerous books on the history of modern physics, including J. Robert Oppenheimer and the American Century. In an interview, he explains Oppenheimer’s role.
Oppenheimer’s name appears in connection with quantum mechanics and black hole theory. How good was he as a physicist?
David C. Cassidy: Well, he wasn’t an Einstein. And it’s not even on the level of Heisenberg, Pauli, Schrodinger and Dirac, the leaders of the quantum revolution of the 1920s. One of the reasons for this is his date of birth. He was born in 1904, so he was three years younger than Heisenberg and four years younger than Pauli. Those few years were enough to place him in the second wave of the quantum revolution and behind the main wave of discoveries, in what the philosopher of science Thomas Kuhn called the “cleanups,” the applications of the new theory.
He is best known for the Born-Oppenheimer approximation, which helped extend quantum mechanics from atoms to molecules.
This was one of his most cited works. He wrote them in 1927 while he was in Göttingen. In the same year, Heisenberg introduced the uncertainty principle. Bohr and Heisenberg presented the Copenhagen interpretation of quantum mechanics. So Oppenheimer made an application, but a good one.
David C. Cassidy is a physicist, historian, and emeritus professor at Hofstra University in New York. He is the editor and author of numerous books on the history of physics.
(Photo: Hofstra University)
Some of his contemporaries said he was an amateur.
He had the skill and the brilliance. But he didn’t have the necessary focus. He did not devote himself to physics as much as one of the great physicists would. She was just one of his many passions. During the time that he was engaged in physics, he read a lot of literature and languages. Also, in the US, the empirical approach to physics was dominant (while the European theorists pursued new concepts, Note d. editor). The task of the theorists was rather to help the experimenters make sense of their data. As the physics and experiments changed, so did Oppenheimer’s interest.
One of his most important contributions had only a tenuous connection to observation, and that was black holes. That was an unfortunate situation. In 1939 he and a student, Hartland Snyder, published a paper in which they predicted that (from collapsing stars) black holes could form, and the whole thing was ignored. They couldn’t follow it up because war broke out. A lot of people just ignored it because it seemed impossible – how can something collapse to an infinitely dense point? It wasn’t until the 1990s that there was experimental evidence of black holes. I believe Oppenheimer would have received a Nobel Prize if he had been alive at the time.
How did the theorist Oppenheimer come to lead the Manhattan Project, a gigantic experiment?
It was even worse. Oppenheimer had no administrative experience. He didn’t have a Nobel Prize, unlike many of the people he was assigned to manage. And worst of all, he came from a dubious political background, with ties to well-known communists in the late 1930s. But Lt. Gen. Leslie Groves single-handedly picked him. First, because of Oppenheimer’s understanding of physics and his ability to explain it to him. On the other hand, because Oppenheimer was highly regarded by the other physicists. But the main reason was that Groves knew that Oppenheimer would be permanently vulnerable because of his political connections. Groves quashed many of the security officials’ reports about him, saying, “I want that man for the job.” So Oppenheimer knew he was only there because he was under Groves’ protection.
“I don’t think he was naive because he knew he was vulnerable.”
Did Oppenheimer make specific technical contributions to the development of the bomb?
In a very important way. In 1942, Roosevelt ordered a bomb crash program. Arthur Compton selected Oppenheimer to lead a theory group at the University of California, Berkeley, to work out all the details – what they would need, how they would do it. The group turned the findings over to Compton, and the Manhattan Project was born. When the scientists arrived at the lab, they received a series of lectures from Oppenheimer’s closest assistant, Robert Serber, on how the bomb would work based on this research. So it was Oppenheimer and his group who came up with all the theory for the project.
In modern parlance, he was therefore responsible for the conceptual design of the matter.
This theory group also dealt with fusion bombs and laid the foundations for the development of a hydrogen bomb. That was put aside until after the war.
Oppenheimer lost his security clearance in part because he opposed development of the hydrogen bomb. He is often portrayed as a tragic figure who was too naïve to defend himself politically. Do you think he was tragic or naive?
I don’t think he was naive because he knew he was vulnerable. And he knew that once he stood up to that bomb they would probably come after him. Of course he was very disappointed. But he didn’t lose his job. He wasn’t blacklisted. He was not forced to emigrate. He was no longer an insider, but he was still a highly respected cultural figure and a spokesman for American science.
This post is from Science Magazine Science. It is not an official translation of the Science-Editorial staff. In case of doubt, the English original, published by the AAAS, applies. German editing: hach