In Interstellar, a key moment happens when Murph (Jessica Chastain) discovers the truth behind the "ghost" in her room. Throughout the film, strange things occur that seem supernatural, but it’s actually something much more incredible. Here's how Murph realizes that the ghost is her father, Cooper(Matthew McConaughey), trying to send her a message.
She realizes this, after seeing strange movements with the books in her room. Cooper, trapped in the tesseract, uses gravity to send her a message by making the books fall in a pattern. He also uses a watch to give her the coordinates for NASA. Murph later understands that the "ghost" was her father trying to help her solve the equation to save humanity.
