Josh Hartnett was one of the biggest stars of the late '90s and 2000s, and with the help of Black Mirror and, now, Christopher Nolan, he's having a 2023 renaissance. Hartnett plays Ernest Lawrence, a nuclear physicist and Nobel Prize winner who worked on the Manhattan Project. He's best known, probably, for movies like The Faculty, Pearl Harbor, Black Hawk Down, and 40 Days and 40 Nights.