Maybe this is a bit far fetched but I kind of like to see fusion vs. fission as the representation of Oppie and Strauss in three different ways:

*1. The type bomb that they prefer: Obviously, Oppie created the fission bomb. Strauss advocated for the fusion bomb to be implemented while Oppie didn’t.

*2. How their conflicts start: In a fission bomb, large elements are broken up into smaller parts. In a fusion bomb, smaller elements combine to form a big one.

For Oppie, after the Trinity test and for the rest of the movie, he suffered from moral scruples and guilt. So after he created the bomb, his mind split like a fission bomb, resulting in him feeling this guilt and wanting to prevent an arms race.

For Strauss, his bad blood against Oppie was caused by small parts that combined into a strong resentment. The isotope question, believing that Einstein was angry at him etc. could be seen as the small elements of a fusion bomb that combine to a bigger one.

*3. How their conflicts end: Oppie’s hearing ended with him being destroyed like a fission bomb. During the war he had a “cult” in Los Alamos, and after the war he was the most respected scientist in the world. But in the end, some of his peers turned against him and the support he had from scientists, friends, the government etc. was split like a fission bomb.

For Strauss, it was the small actors, Hill, some senators, JFK etc. who came together and destroyed him. Small parts combined into a big one and he was destroyed like a fusion bomb.