The essence of every Christopher Nolan movie can be summed up by a ticking clock, from the reverse storytelling in Memento to the time inversion in Tenet.Interstellar is no different. Its depiction of theoretical astrophysics has made it one of the best sci-fi movies of all time, both in terms of storytelling and the scientific aspects it portrays.
Featuring a dystopian future, wormholes and the fifth dimension, it makes sense that the ending of Interstellar can seem a tad confusing. The ambitious plot is driven by the simple idea that both hardcore science and close relationships are needed to address basic human desires, and the ending emphasizes those themes.
A Brief Summary of Interstellar
There is a crop blight on Earth in 2067, which has led to a shortage of food and other resources. The film introduces Joseph Cooper, a widower, a former NASA pilot, and currently an average farmer. He lives with his teenage son, Tom; 10-year-old daughter, Murph; and his father-in-law, Donald.
When he discovers a pattern on his bedroom floor after a massive dust storm, Cooper believes that gravity variations caused it. After some calculations, he realizes it represents geographic coordinates in binary code. He follows these to a secret NASA facility, which is led by Professor John Brand. Brand informs Cooper that, around 48 years ago, a mysterious wormhole was identified near Saturn, opening a pathway to the ‘other side,’ which has 12 potentially habitable planets orbiting a black hole called Gargantua. Volunteers have traveled to the distant galaxy to investigate, and three of these planets seem promising.
Brand presents two plans that can secure humanity’s survival. Plan A involves solving an equation for the anti-gravitational propulsion theory, which would enable NASA to create large space stations that can transport human settlements to outer space. On the other hand, plan B is to launch the spacecraft Endurance with 5,000 frozen fertilized eggs, to establish a colony on another planet.
He asks Cooper to complete the mission and lead a team that includes Dr. Amelia Brand, Romilly, and Doyle. Cooper agrees and, before he leaves, gives his daughter a watch to keep a track of time till he returns. Unfortunately, after visiting the first two prospective planets, the Endurance crew learns that they are unable to sustain human life. Both Doyle and Romilly die during the mission. Plus, the time dilation due to the proximity to Gargantua causes 23 years to pass on Earth since the mission started.
To make matters worse, Murph (who is now a NASA scientist) learns from a dying Brand that he had lied about solving the gravity-equation, as only information from inside the black hole can help achieve that. Cooper and Dr. Brand only realize this after Murph sends a message to Endurance.
What Interstellar's Ending Means
There is not enough fuel for Endurance to return to Earth. The looming black hole poses a threat to the remaining members. Cooper decides to detach TARS, an AI robot, to shed some weight and also collect the quantum data needed from inside the singularity. Cooper also sacrifices himself to increase Dr. Brand’s odds of reaching the last possible habitable planet to restart the human race with the embryos that are on board. As he uses a slingshot move around Gargantua to propel the spacecraft to the final planet, he detaches himself and prepares to be drifted off into the black hole.
Once he passes through the event horizon, he enters a tesseract, which is a construct that gives him access to a fifth dimension. This is where every moment in time exists all at once. For Cooper, it is physically represented by Murph’s bookshelf, through which he can see her childhood bedroom. When he sees the young Murph, he desperately tries to send her a message to stop his past self from going by sending the message “S-T-A-Y” in Morse code. He thinks this will somehow reunite him with his family, and he wouldn’t lose all the years gone by. However, as seen in the beginning of the film, Murph did receive his message, but she is unsuccessful in getting him to stay. This proves that Cooper cannot go backwards to alter the past, plus time is not linear here.
TARS deduces that they have been brought here because they were protected by “them” — the “bulk beings” that are referenced throughout the movie. It is this future civilization that placed the wormhole, allowing the astronauts to travel to the other planets in the first place. It is they who built the tesseract as a library for Cooper’s understanding. However, despite their ability to travel through infinite time and space, they cannot communicate through dimensions or pinpoint instances in time. This is where Cooper’s human limitations become useful; he can connect to specific moments as he is bound to another human being from another dimension. Thus, he can use gravity to send a message to Murph at the right point in time. This helps Cooper realize that “they” are actually “us” — advanced human beings who have evolved past all dimensions.
He uses dust to communicate the coordinates to the NASA base in binary code. These turn out to be the same ‘anomalies’ he had witnessed early on in the movie, which ultimately send him on the mission to get the quantum data. He then asks TARS for the quantum data it had extracted from the black hole, which he then relays to Murph in the form of Morse code on the same watch he had given her.
When TARS questions him why he is sure that she will be able to make the connection at any point, he quotes what Dr. Brand had explained before: love is the only thing that can transcend all dimensions, including space and time. It is this that leads him to believe that she will visit her childhood home to find the watch he gave her. As soon as he completes his purpose, Cooper is ejected from the tesseract and wakes up some time later on Cooper Station, which is orbiting Saturn. It is there that he finds a now aged Murph on her deathbed. Due to the ‘time slippage’, around 51 years have passed for those on Earth, while it has only been a few hours for Cooper.
It turns out that Murph was successful in solving the gravity equation, which allowed the launch of space stations into space to build colonies. She tells Cooper that she is not going to live much longer and urges him to go find Dr. Brand instead, who was last seen breathing in the air on the third planet and preparing to repopulate it. Cooper takes her advice and steals a ship to go back through the wormhole and join her.
The meaning of Interstellar lies somewhere between science and sentiment. It is a story of a father and daughter, as well as of humanity coming to terms with its own extinction. It also explores the inevitable results of climate change, which would make the Earth uninhabitable in the distant future. The film encourages the audience to think about how human connections go beyond just immediate families; the future species need to be saved too.