There's a mystery posed toward the beginning of Interstellar: "Someone" has planted a wormhole in our solar system to help humans explore space and, presumably, find a new planet to move to from blight-stricken Earth. Desperate for the manufactured escape hatch, no one is concerned with who put it there. Much like human DNA, the plot of Interstellar loops into itself: The solution to the puzzle — who is out there helping mankind escape Earth? — is that mankind is out there.
If you have not seen the film and do not wish to know more of its secrets, now is a good time to stop reading. Once the camera follows the main character into a black hole, we learn that humans of the future have reached back through space-time to pull their glorious past-selves up by the bootstraps. And, in an unwitting partnership with these future-humans, Matthew McConaughey's Cooper, our hero, hurtles into the fifth dimension in a black hole and then reaches back through space-time to send himself and his daughter a message in Morse code. The astronaut is afloat in a hazy space made comprehensible by future-humans: He drifts, apparently, behind the bookshelf, where he can peer out into his daughter's room at different points in the Earth's past, an array of infinite possibilities fanning out in every direction. Over nearly three hours of meditations on gravity and wormholes and black holes and relativity, Interstellar ultimately tells us that humans are saved by love — by human love for its own species, which capitalizes on a man's love for his own daughter.
"Love is a fascinating thing," Jonathan Nolan, who wrote the screenplay with his brother, director Christopher Nolan (Inception), told BuzzFeed News. "Our emotions are wild, uncontrollable things that we're still very connected to. What they mean is a question that's asked explicitly in this film. Do they mean anything, these emotions, these feelings we have?"
Interstellar answers its own question with a resounding "yes," an affirmative that the Nolan brothers secreted into the very beginning of the film. Cooper's daughter, Murph (Mackenzie Foy), believes there is a ghost in her bedroom, knocking things off her bookshelf and communicating through code: We learn later that in fact Cooper himself is reaching from a black hole to alter gravity on Earth and send Morse code messages to his daughter. Love transcends time and space, through a child's bookshelf. The bookshelf, though, is more than just a symbol for collective human knowledge and culture that Cooper and his daughter intend to save.
"I have a little girl, and she begins every day by gathering all of her books and piling them on the bed so we can read as many of them as possible before it's time to get up and get dressed and get breakfast," Nolan said. His daughter is just about a year old, and now the bookshelf is "much more loaded for me than it was when I first started writing the project."
"With kids, it becomes this very intimate thing," he said.
Nolan was brought onto the project by Lynda Obst, who produced Interstellar — Obst had already been working with physicist Kip Thorne and Steven Spielberg to develop the film when Nolan was hired to write the screenplay. Thorne, executive producer and physics consultant, had laid the scientific groundwork, and Nolan conceived of the space exploration movie as "a homecoming affair" — Christopher Nolan would work with him on writing subsequent drafts. Thorne was instrumental throughout the process, edifying Nolan on the conceit that would give the film its circular shape: The "ripples through the fabric of space-time itself. Not like light waves. These are ripples through the very fabric of the universe. He's spent many, many decades trying to articulate this phenomenon to laypeople." It's "not intuitive" how these things would look — the wormhole, in particular, is "a ball that is also a tunnel," into which light and matter bend strangely, and required Thorne's expertise to visualize.
The specifics of what would happen to Cooper in the holes both worm- and black that he goes into changed over time, but "the larger picture of leaving home, to be reunited with your family, was always the central idea of the pitch from the beginning," Nolan said. He always had a rough idea of how these gravitational phenomena would look because of Thorne, but he did not know how the visuals would be accomplished onscreen.
"It's the screenwriter's job to not give a flying fuck about how these things are gonna get made," Nolan said. "I think you're not really doing the job of the screenwriter if you worry too much about the production constraints or the reality. That should be someone else's problem."
There's another mystery in the very casting of the movie: Why was Matt Damon's role as Dr. Mann kept hush-hush? Damon, the considerably famous Academy Award–nominated actor, emerges from a cryogenic sleep pod well into the movie, without much hint beforehand in the publicity of Interstellar that he was in the film. Nolan said he and his brother wanted to cast Damon ("he has this incredible presence as a human being"), but he didn't want the audience to be wondering where Damon was for much of the movie. Instead, he opted to trap the audience in the protagonists' perspective, so that when Cooper and Anne Hathaway's character open the life-support pod, "there's gonna be a guy in there, and you don't know who that person is or what their motivation is."
Surprise! It's Matt in the box.