Implosion
- Ted Hall is writing a coded letter to Saville Sax using "book code" to establish a meeting date.
- Sax tells everybody he's interested in attending the University of New Mexico (way to establish an alibi, Sax).
- They meet in Albuquerque to exchange information. Sax relays a technical question the Soviets have for Hall, and Hall gives Sax two pages of handwritten notes, including everything he knows about the plutonium bomb.
- Sax copies Hall's notes onto a newspaper with milk for ink. It's invisible once it dries until the paper is heated. Cool, huh?
- Meanwhile, in February of 1945 in Europe, Sam Goudsmit and the Alsos team are right behind the Allied forces slicing through Germany. There they corner Walther Bothe, a German physicist, who isn't particularly forthcoming with information about Germany's atomic program.
- They do learn that Werner Heisenberg and the rest of the German physicists have been moved to a town called Haigerloch.
- At Los Alamos, Oppenheimer is even more stressed out than ever. His scientists are still puzzling out how to build a plutonium bomb, and they're not having much success.
- They basically need to figure out how to create a perfectly symmetrical explosion inward onto chunks of plutonium—therefore creating a critical mass and starting a chain reaction.
- Oppie puts George Kistiakowsky ("Kisty" for short) in charge.
- Kisty decides he needs to have a hundred or so pieces of plastic explosives strategically placed and timed to all go off within a millionth of a second of each other.
- This takes a ton of trial and error—and Ted Hall. He's in charge of figuring out what implosion looks like on a metal ball.
- After a bunch of tests, they realize they've figured out how to build the plutonium bomb. Yay.
- (But the guy that knows the most about it is a KGB informant. Boo.)
- Saville Sax passes on Hall's information, but now the KGB is worried that it is disinformation—which could lead to quite a few heads rolling. They want Fuchs to corroborate Hall's report.
- Gold is told by Yatzkov to contact Fuchs right away.
- He meets Fuchs in Cambridge, Massachusetts (at his sister's house, once again), where Fuchs gives him his own report.
- It will be impossible to get away from Los Alamos again (it's the final push toward building the bomb), so their future meeting place will have to be in Santa Fe.
- Gold tries to offer Fuchs money for his report, and Fuchs is offended by the gesture.
- Both of the reports from Fuchs and Hall make their way to Igor Kurchatov, the lead physicist at Laboratory Number 2 outside Moscow, who is like, "Hey. Sweet. They did all my work for me. Let's build us an implosion bomb."