Not many Hollywood blockbusters need to be explained by a theoretical physicist, but Interstellar is more complex than your typical sci-fi jaunt. Christopher Nolan’s 2014 epic follows former NASA test pilot turned farmer Joseph ‘Coop’ Cooper (Matthew McConaughey) as he travels via wormhole to outer space in search of humanity’s new home. Add in a prophetic “ghost”, some complex family relationships and a lot of head-scratching shenanigans about time and relativity, and it’s little wonder people often have a lot of questions when the credits roll
As the film returns to cinemas for a slate of tenth anniversary screenings, here’s a handy explainer for any newbies looking to make sense of the twisting space drama.
Why all the secrecy about space travel?
Interstellar is set in the near future, with humanity on the verge of extinction thanks to a climate crisis that causes drought and dust storms. Because of this, the people in charge have decided to focus all their efforts on feeding the population rather than funding space exploration. To stop any pushback, they have also claimed that the 1969 moon landings were faked with former NASA pilots, such as Coop, forced to retrain as farmers.
What’s with the “ghost”?
During one of the storms, Coop and his daughter Murph (Mackenzie Foy) observe some dust acting weirdly in her bedroom. She blames it on a ghost but the pair quickly figure out that the gravitational anomaly actually points them towards a secret NASA research lab, which kickstarts a chain of events that eventually sends Coop through a wormhole in search of humanity’s salvation while Murph dedicates her life to science.
At the end of the film, our plucky explorers are travelling on a spaceship that’s rapidly running of fuel. To ensure they can make it to safety, Coop sacrifices himself by ejecting his pod and falls through a black hole. Rather than being killed though, he wakes up and finds himself in a library that lets him observe moments from his daughter’s life. In one of the scenes, a grown up Murph (Jessica Chastain) uncovers an old notebook that she used to learn morse code with her dad – and realises that he was the one sending her messages via dusty gravitational anomalies this whole time. “You were my ghost,” she says.
Coop then realises he can “exert a force across space time” and sets about transferring the vital, planet-saving data he’s also been collecting, using a wristwatch he gave Murph before he blasted off into space. It allows her to create a series of space stations that save humanity.
The idea of Coop being her ghost also ties into Interstellar’s more emotional themes of parenthood and loss. Just before he leaves on a rocket ship, Coop tells Murph, “Once you’re a parent, you’re the ghost of your children’s future.” How right he was.
So what actually happens at the end of Interstellar?
Interstellar features a two-pronged attack to save the world. Coop and his team set off through a black hole to investigate new planets that could provide a viable new home for humanity, while Professor Brand (Michael Caine) stays on Earth to work on giant spaceships that could support the entire population. But it turns out Coop’s mission is actually just a ruse that allows Brand to gather much-needed data, with his work continued by Coop’s daughter Murph after his death.
After two disastrous missions for Team Space, they make a last-ditch effort to reach the third and final potentially hospitable planet. With their ship running out of fuel though, Coop ejects himself into the vastness of space to help co-pilot Dr Brand (Anne Hathaway) make it to safety. Tumbling into a black hole, he works out how to communicate with his now-adult daughter and realises the whole mission was the work of future humans, who were manipulating the present to ensure their own survival in a neat, if confusing, time loop.
The film ends with Coop waking up decades in the future on one of the population-saving giant spaceships, having barely aged a day because he’s been cryogenically-frozen while travelling in space. At the same time, Murph has lived an entire lifetime and the pair have a deathbed reunion. With humanity safe and their work done, she encourages him to seek out Brand. She’s off “setting up camp” on the planet they were both trying to reach earlier in the film and he steals a spaceship to make the perilous journey to her. A happy, if bittersweet, ending.
And what next?
With the spaceship orbiting the black hole, it’s suggested humanity is preparing to make the jump to the third planet that Brand is currently turning into a “new home”. While we aren’t told what happens next, we know humans survive long enough to evolve into dimensional-bending, gravity-nudging beings able to send messages across galaxies, which feels like a hopeful note to end things on.
Why was Dr. Mann such a bastard?
Matt Damon’s Dr. Mann landed on an uninhabited planet as part of an earlier mission, and told the others it would be the perfect alternative to Earth. Coops and Dr. Brand then followed him out there but after landing, it’s revealed Mann was lying. Turns out his planet is a hellhole and he’ll do anything to escape, including trying to murder them both and steal their ship.
His backstory is explored in a prequel comic written by Nolan but according to the director, Mann was driven by “selfishness and cowardice”, because faking the data and getting another ship to follow him was the only way he’d survive.
“It’s the kind of sequence where you loathe the guy because he’s doing something that you feel you might wind up doing in a similar situation,” said Nolan. “Loneliness and desperation will make us do crazy things”.
Why didn’t the future humans just travel back in time?
Perhaps the biggest headache with Interstellar comes from the idea of future humans building the strange, sci-fi library to ensure Coop could relay the apocalypse-avoiding data back to earth. If “they” need Coop to save them, how did they originally survive Earth’s destruction?
While this isn’t directly answered in the film, it relies on the bootstrap paradox and the idea of time being circular, rather than linear, which is an ongoing philosophical and scientific debate and not just pure fantasy. It’s where that theoretical physicist comes into play.
But why did “they” go to all that trouble, rather than just giving Brand the data he needed right at the start of the film? Well, according to the NASA team orchestrating the whole mission to save the planet, future humanity has evolved beyond our four-dimensional way of understanding the universe and can only leave breadcrumbs via binary messages for them to follow.
All the population-saving information is also collected directly by Coop and his team, suggesting “they” can’t actually affect the past, ruling out Terminator-like time travel. Plus, that would make for a very different, much shorter movie.