Acclaimed filmmaker Christopher Nolan claims that early audiences for his upcoming biographical drama Oppenheimer have left the theatres silent and haunted. During an interview with Wired, Nolan describes the timely themes of his biopic and how they can affect those who see the film.

Nolan explains how he wanted the film to illustrate the difficult questions that the real J. Robert Oppenheimer faced while helping develop the nuclear bomb before World War II. To Nolan, there were no easy questions that could be solved in under two hours, especially with the difficult conversations surrounding nuclear weapons both back then and today. Even if he brought in some hope during its development, Nolan acknowledges that “there’s this sort of overriding bigger question that hangs over it.” He felt it was essential to leave “questions at the end that you leave rattling in people’s brains and prompting discussion” revolving around McCarthyism, the atomic age, and nuclear technology.

Historian Kai Bird, who wrote American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer, gave praise for Nolan’s adaptation of his work and expressed awe at how he tackled complex themes. Much like Nolan’s audiences, Bird claims that the film left an enormous impact on him, leaving him stunned and still “emotionally recovering.” At an Institute of Advanced Study conference, Bird calls Nolan’s work an artistic achievement that can hopefully “stimulate a national, even global conversation about the issues that Oppenheimer was desperate to speak out about.”

Oppenheimer is slated to be released nationwide to theaters on July 21 by Universal Studios.