“What do you expect from theory alone?” That question and variations on it echo throughout the new movie Oppenheimer. It also provides the central throughline, as wartime ambition and hope give way to paranoia and military escalation. What is nominally a biopic of physicist J. Robert Oppenheimer ends up a dark prophecy of how the Cold War arms race and the chain reaction it caused could lead to global destruction.

Adapted from Kai Bird and Martin J. Sherwin’s 2005 biography The American Prometheus, the film charts Oppenheimer’s (Cillian Murphy) life from a student of the new field of quantum physics to his time as director of the Manhattan Project and his fall from grace after a scheme to strip him of his security clearance turns the “father of the atomic bomb” into a pariah in the Atomic Age. Director Christoper Nolan, the man behind the narrative twisting film Memento and the epic Dark Knight Trilogy, might seem like an odd choice for this project, but he turns a life story into a thriller as tense as a countdown to a nuclear test, even if the completion of the atomic bomb is guaranteed to any modern audience.

J. Robert Oppenheimer was a complex figure and the film weaves through several different threads. With the outbreak of World War II, Oppenheimer and other physicists join the Manhattan Project, scared of what could happen if the Nazis developed an atomic bomb first. The film tackles the research at Los Alamos itself, but also the tensions so many of the scientists involved, Oppenheimer included, dealt with thanks to their own left-wing views, views the authorities gave leniency to in the war due to the need for their minds. Post-war pettiness and distrust eventually bubble up, pitting them against one another while their creation spirals out of their control. 

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As a film, Oppenheimer is fantastic and never dull. There’s exposition, yes, but this isn’t a science lecture. Nolan, along with an excellent cast, fill Oppenheimer with passion and suspense. The idea of theory versus real-world practicality drives much of the tension. The scientific work presents its own hurdles, but the best moments come from the other challenges the Los Alamos scientists face. The military’s effort to keep the Manhattan Project secret and compartmentalized goes up against the scientists’ wishes to better communicate, and their trust in Gen. Leslie Groves (Matt Damon) hits the security apparatus meant to keep their work hidden. What do you expect from theory alone? 

As Oppenheimer later notes, the military and the world won’t understand nuclear weapons and quantum mechanics until they have a material example. For Oppenheimer, it’s an idealistic hope that one destructive act can pave the way for peace. For the rest of the world, it’s a shocking spark that lights the fire for greater fear, paranoia and arms stockpiling. It’s a striking choice that the Trinity Test — recreated without CGI — comes midway through the film, rather than as a climax to the film. 

There’s the test itself. It is both awe inspiring and dreadful on screen but not the climax to World War II or the film. As the countdown reaches zero, a pillar of smoke and red fire erupts over the New Mexican desert. The sequence is striking, almost entirely without sound. This is not the bombastic explosions of a Michael Bay film, or the massive spectacle of the then-largest cinematic explosion seen in Spectre. It’s thrilling, yes, but it’s not a moment of adventure.

Although still a biopic, the Trinity Test marks a turn in the movie’s style and tone. An energetic drive toward scientific discovery fades, and Nolan instead imbues the film with a real-world sense of horror. Oppenheimer is haunted by visions and sounds of devastation. His guilt builds up and certain scenes take on a washed out brightness, echoing the Trinity blast. His efforts to reach arms control agreements are stymied by a national security system empowered by his creation. “What do you expect from theory alone?” The detonation gives way not only to the ever-present danger of nuclear weapons and their destructive power, but a new wave of paranoia. The discoveries of the Manhattan Project created a new world, outside of the control of the scientists at Los Alamos and emboldened a security apparatus that saw threats everywhere. The fallout is immense.

The story wouldn’t work if the cast couldn’t anchor it. Murphy embodies Oppenheimer, mixing idealism and wonder with jaded charm and eventual despair. Equally compelling is Emily Blunt as his wife Kitty, who takes greater prominence and nearly steals the film in the later Red Scare segments of the movie. As the main military figure in the film, Damon is a direct force, moving with the focus and pace of an officer in command, giving orders and expecting quick work. His interplay with the scientists at Los Alamos provide some grounded humor, while supporting turns from Jason Clarke and David Dastmalchian as opponents of Oppenheimer have an understated menace. As Atomic Energy Commission head Lewis Strauss, Robert Downey Jr. gives an excellent dramatic turn, using his Tony Stark charm to great effect as Oppenheimer’s rival. Benny Safdie — yes the co-director of the Adam Sandler thriller Uncut Gems — is equally engrossing and tense as Dr. Edward Teller, himself known as the “father of the hydrogen bomb.” The film does not have a weak link in its performances. 

For a movie about World War II, and about the birth of the Cold War, much of Oppenheimer is about what it doesn’t show. There are no combat depictions, no scenes of the war the scientists are so desperate to bring an end to. The Manhattan Project was pulled together specifically to beat the Nazis to the atomic bomb — and as the film points out, the Jewish background of many of the scientists, who know the horrors unleashed by Hitler, added extra urgency to their mission — but the bombs were only used once Germany surrendered and the war was at Japan’s front door. The film weighs the ethical debate of using such devastating weapons, but also never shows them used on Japan. The impacts on Hiroshima and Nagasaki are referenced but never shown. 

If there is a fault in Oppenheimer, it’s here. For a film so dedicated to weighing theory versus reality, the lack of those depictions is noticeable. There is a fantastic scene where the scientists hear haunting descriptions of how people in Japan suffered after the bombings, but it never leads to more. The long-term health issues from nuclear weapons goes unmentioned. Despite a timeline stretching into the 1960s, concerns over life for Trinity Downwinders and people near nuclear test sites goes unmentioned — curious considering Strauss’ role in downplaying the dangers while head of the AEC. The film grapples with the legacy and danger of nuclear weapons but seems averse to showing the human impact

Ahead of the movie’s release, Nolan said that “it’s very easy to make the case for Oppenheimer as the most important person who ever lived,” given the impact of the Manhattan Project. It reshaped the world, both culturally and in the way militaries imagined war, and what damage they could do. In Oppenheimer, Nolan and his cast make the case not just for Oppenheimer’s importance, but also for the dangers of the legacy he left behind. 

Oppenheimer is in theaters now.

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