Two Mavericks

Edward Teller and Seth Neddermeyer both brought unconventional ideas to the Manhattan Project. One might have tanked the project had Robert Oppenheimer not kept him on a short leash. The other saved the project.

Teller was obsessed with the “Super,” a bomb that relied on hydrogen fusion rather than uranium fission to release enormous amounts of energy. When the project needed his efforts to go in another direction, he refused. He ultimately took his ambition and resentment to damaging Oppenheimer in the 1954 hearing that you will hear more about as news of the film comes out. But you probably haven’t heard of Neddermeyer.

In a meeting in April 1943, Neddermeyer noted that the gun arrangement of attaining a critical mass was one-dimensional. How much better, he enthused, to do that in two or even three dimensions! Most of those present thought it a physically unattainable goal: how to make the implosion uniform and avoid having the material squirt out like squeezing a handful of water. Even Oppenheimer, who had brought Neddermeyer into the project, was skeptical. But John Manley decided to make Neddermeyer the group leader for implosion physics to force him to flesh out his ideas.

Neddermeyer started with two dimensions: wrapping explosives around pipes and squashing them down to a solid bar. The ordnance people were unimpressed, as was Richard Feynman: “It stinks.”

Neddermeyer continued his experiments. The gun weapon program using uranium-235 continued uneventfully. The neutron cross-sections for uranium-235 were well known and supportive of the gun design. Nobody had any doubts it would work. But plutonium had been available only in microscopic amounts until June 1944. Neutron measurements showed that it could not be used in a gun design.

That spring had seen both Teller and Neddermeyer in disagreements with other project members. Oppenheimer’s solution for Teller was to tell him to work on the Super full time, which would get him out of other people’s hair. He made Neddermeyer a senior advisor to the implosion team and put George Kistiakowsky, who had arrived a few months earlier, in charge of developing implosion.

Neddermeyer’s implosion was the only way forward. The project was reorganized around it. The Trinity test was a test of a plutonium weapon of implosion design. As Oppenheimer is reported to have said at the time, “It worked.”

I’ll be interested to see how the film treats these two subplots. Both are essential to Oppenheimer’s story.

You can expect to see reviews of the film to start dropping later today. A number of people have attended early screenings, and the embargo on writing about it ended at noon (Eastern Time, I think) today.

Neddermeyer’s history based on Richard Rhodes’s “The Making of the Atomic Bomb.”

Cross-posted to Nuclear Diner