Christopher Nolan's Oppenheimer runs 180 minutes and operates on three parallel timelines simultaneously. It is not a film you can half-watch. It is, however, one of the most formally ambitious blockbusters ever made โ and its technical achievement is inextricable from its emotional one.
The short answer
Oppenheimer is engaging almost from the opening scene, but it becomes genuinely extraordinary around 2 hours in, when the Trinity test sequence arrives. Everything before that is exceptional setup. The trial sequences that dominate the final third are the film's most dramatic stretch.
The three-hour roadmap
Hour 1: The Making of a Physicist (Score: 74/100)
Young Oppenheimer studies in Europe, returns to America, and becomes one of the most prominent theoretical physicists of his generation. This section establishes his brilliance, his ego, his complicated politics, and his romantic life. It moves quickly for a 60-minute character study.
Hour 2: The Manhattan Project (Score: 88/100)
Los Alamos. The assembly of the greatest scientific minds in history in the New Mexico desert. Nolan depicts the scientific process with remarkable clarity. The building tension toward Trinity becomes almost unbearable. This is the film's most propulsive hour.
Hour 3: The Reckoning (Score: 91/100)
The security hearings. Oppenheimer stripped of his clearance, his legacy attacked by political enemies. Cillian Murphy's performance in these sequences is among the finest of his career. The parallel hearing involving Lewis Strauss adds a thriller dimension to what could have been dry procedural drama.
The verdict
Oppenheimer is Nolan's most mature film โ less interested in formal trickery than in genuine moral weight. The three-hour runtime is justified. The performances are extraordinary. The Trinity sequence alone is worth the price of admission. But it requires your full attention for the entire runtime, which is not always comfortable.