Director Christopher Nolan discusses his new film ‘Oppenheimer,’ the threat of nuclear war, A.I.’s “Oppenheimer moment,” his approach to historical narrative, working with Matt Damon and his interest in “high stakes” issues -- like war, WMDs, and the nature of good and evil – spanning his films from Dunkirk to the Dark Knight trilogy. This wide-ranging interview is a new installment of The Summit Series with Ari Melber, featuring discussions with leaders at the summit of their fields.