the ending sealed the 5th star for me.
the ending was so chilling, haunting and horrific of what was to become of the world after. You can feel all of the pain of that bomb, the cries of the world and the terrible fear, sadness and terror R.O feels knowing of what has now been invented.
It is long, a bit slow, but the ending had me feeling, rage, terrible sadness, terror all the intense emotions one could feel, thinking of all the "what ifs" if this bomb was not invented and detonated.
Christopher Nolan as always....mind blowing.