We follow from Cooper’s perspective as the Endurance disappears from view and he crosses slowly past Gargantua’s event horizon. The universe falls out of view and blackness overtakes him. He calls out to TARS but receives no answer. The Ranger’s screens begin to fail. He sees a snow-like substance flying by as he loses control of the Ranger and the computers die. Next, what look like sparks begin to pass by. The Ranger starts to break apart as Cooper screams.
Back on Earth, Tom and some others fight the raging fire. Murph finds her broken space lander toy as she hears Getty shout for her. Meanwhile, Cooper hears the Ranger telling him to eject. He does so, slipping from the craft into total silence and darkness. For a moment, we hear only his labored breathing, and then suddenly he is flying down a seemingly endless array of geometric images and light, a hallway of unidentifiable brown and black blurs. He screams as he comes to a halt.
Gaining his bearings, Cooper realizes that he’s in some alternate dimension, a realm of walls manifesting with the image of books all around him. In places, the books are visible as normal, but in others the lines of their image stretch off endlessly, intersecting with other lines to form an infinite series of rectangular prisms. Cooper peers through one wall of books as if looking through a window and sees Murph’s old bedroom beyond it. He begins banging and knocks a book loose. It falls, startling 10-year-old Murph. The book knocks her toy lander to the ground, breaking it. Young Murph approaches the bookcase. Adult Murph, in her own time, does the same. Cooper begins screaming as he watches young Murph take the toy lander downstairs, presumably to show her father that it broke as she did in her first scene in the film.
Cooper looks around at the endless lines of books that stretch in all directions and begins to cry and scream. He floats through dozens of geometric manifestations of his daughter’s bookshelf, each one a window into a given moment in time within her bedroom. He sees young Murph slamming and barricading her door after coming home from NASA with him, as happened earlier in the film. She sits on her bed as adult Murph sits in the same spot, 25 years later. (What we are witnessing is young Murph in her own timeline, adult Murph in hers, and Cooper observing from a place outside both.)
Cooper watches his former self attempt to enter Murph’s barricaded door. He screams for himself not to go, and begins pushing on the books again, spelling out “STAY” in Morse code, just the way Murph discovered it at 10 years old. Adult Murph begins pulling out the same books to recreate the message. Getty yells for her to hurry. She places the watch on the shelf and thinks.
Cooper watches young Murph write down the Morse code and then sees himself enter her room to try to comfort her about his leaving. He watches Murph grow angry and throw the watch, and then sees himself give up and leave as she cries. From his strange dimension, Cooper begins to cry as well, begging Murph to make the other Cooper stay. He bangs again on the wall of books and knocks another one off, causing the other Cooper to stop momentarily, as he did when it happened earlier in the film, but then leave as he did before. Meanwhile, adult Murph finds the message “STAY” in her old notebook.
As Cooper cries, TARS begins to speak over his transmitter, saying that “they” saved Cooper and TARS by creating a 3-dimensional space inside their 5-dimensional world so Cooper could experience time as a place. TARS calls Cooper’s location a tesseract, and says he can use gravity to communicate with Murph across time, as he’s been doing by knocking the books off of her shelf. TARS also confirms that he has the quantum data necessary to solve the gravity equation, thanks to the black hole, but that his current transmissions aren’t reaching anyone.
Getty yells to adult Murph that the fires are out and that Tom is on his way back to the house. Meanwhile, Cooper realizes that “they” didn’t bring him there. Humanity did. “They” is future mankind, inconceivably advanced and somehow capable of experiencing time as a fifth dimension. They placed the wormhole near Saturn to give present-day Earth access to new worlds. And now, they’ve given Cooper a way to send Murph the answer to the gravity equation via the tesseract.
Cooper has TARS transmit the quantum data to his helmet as binary code. As he does this, he finds the moment in time when Murph left her window open during the dust storm and uses his hand to manipulate gravity and give his former self the coordinates to NASA in the dust lines on the floor. Meanwhile, adult Murph remembers that gravity was her ghost. Cooper tells TARS that “they” (future mankind) chose Murph to save everyone. He begins flying through the tesseract as if floating down an infinite hallway, passing representations of every moment of time in Murph’s bedroom. He plans to use his love for Murph to find her across time and give her the quantum data, just as Brand said love could transcend time and space when she talked about Edmunds. Cooper plans to move the second hand of the watch he gave Murph to transmit the quantum data in Morse code. TARS is doubtful, but Cooper insists that adult Murph would come back for the watch. He moves his hand through the tesseract wall, manipulating the watch hand, and at the same time we see adult Murph discover its movement.
Getty gets a crowbar from the car as Tom and his friends approach, ready to fight them off. Murph gasps and flies out of the house with the watch, saying her father is going to save them. She embraces a very confused Tom. Next, we see her writing out the morse code the watch is transmitting. She erases the boards in Professor Brand’s office and begins her calculations anew. Then we see her run through the space station, past a confused Getty, and throw her papers over the railing, shouting, “Eureka!” She calls it tradition and plants a kiss on Getty in celebration.
TARS says he thinks Murph received the data, since the “bulk beings” (the future humans) are now closing the tesseract. Cooper says that one day civilization will evolve past the four dimensions we know and create the tesseract to save themselves. The tesseract slowly dissolves away to white light. Cooper closes his eyes, and then we see him flying through the wormhole as he did before, but this time in reverse. He reaches into the Endurance and connects with Brand’s hand, revealing that it was he who created the unidentified distortion when they passed through the wormhole earlier.
In an instant, Cooper is floating in space with Saturn not far behind him. We then see him wake up in a hospital bed, where a doctor and nurse tell him to take it slow, as he’s technically 124 years old. They say he was found with only minutes left in his oxygen supply. Cooper goes to the window and sees a baseball game being played on a field outside. The boy at bat hits the ball upward, where it strikes the window of an upside down house above their heads. They are in a vast, cylindrical ship in which centrifugal forces mimic gravity to keep them bound to the ground, such that every inch of the ship’s rounded insides can be inhabited. The doctor tells Cooper that they’re in Cooper Station, named for Murph. The ship is orbiting Saturn, and Murph, now very old, will arrive from another ship in a few weeks to see him.
A few days later, a young man leads Cooper around the ship. They pass by a hangar full of Ranger-like crafts before arriving at Cooper’s old farmhouse, now kept in perfect condition aboard the station, surrounded by acres of corn. Screens around and inside the house display the interviews shown at the beginning of the film, detailing what life was like during the time of the blight and dust storms, as if in a museum. Inside the house, everything is exactly as it was on Earth, albeit without the dust. Coop finds a roughed-up TARS in the living room. The man says they found him floating near Saturn as well, and that he just needs a new power source.
Later that night, Cooper brings TARS back to life on his kitchen table, setting his honesty at 95% and humor at 75%. When TARS pretends to initiate a self-destruct mode, Cooper brings the humor down to 60%. He then enjoys a beer on the porch like he and Donald used to do, but says he doesn’t like pretending that mankind is where they were, but instead wants to know where they’re going.
A nurse tells Cooper that Murph was in cryo-sleep for two years as she leads him into her hospital room. Cooper enters it to see Murph’s children and grandchildren around her bed. An organ chord crescendoes as it did at the beginning of the film as Cooper's eyes fall on a bedridden Murph, now ancient and hooked up to multiple machines. When Murph sees him, she immediately begins to cry. Cooper tells her that he was her ghost, and she says she knew, though no one believed her, thinking she solved the gravity equation on her own. She shows him his watch on her wrist, and then sends him away, saying he shouldn’t have to watch his child die, that her children will be with her. She tells him that Brand is waiting for him, and her words turn to narration as we see Brand setting up camp on a sunny, desert-like planet with CASE.
Cooper and TARS sneak into the hangar full of Rangers and commandeer one. We see Brand build a makeshift grave for Edmunds. Murph narrates that Brand is settling down for a nap by the light of their new sun, on their new home. We see a shot of Brand walking away from us toward a brightly lit, fully operational settlement of her own construction. The music crescendoes, and then the screen turns to black.
Section 6 Analysis
In the film's final section, we travel from practical theoretical physics to the most fantastical part of the story. While no one is sure exactly what it’s like inside a black hole and what Cooper or TARS would discover upon entering one, it’s generally agreed that the gravity below the event horizon would kill any living thing inside it. Dr. Neil deGrasse Tyson has explained, directly referencing Interstellar’s climax, that Cooper would likely have been stretched to death like a piece of spaghetti by Gargantua’s intense gravity once the Ranger broke apart. Whether or not the "bulk beings" were able to send him into the tesseract before he met this fate is a question whose answer can only be known by the screenwriters.
The major plot twist in the film’s climax is that the “ghost” inhabiting Murph’s bookshelf was Cooper all along, trapped in an alternate 3-dimensional world in which gravity travels across time. This revelation explains the various, mysterious moments we experienced earlier in Murph’s bedroom: books falling from the shelf, dust settling on the floor in lines that spell out coordinates, and the word “STAY” written in Morse code. But Cooper’s presence within the bookshelf is also a giant paradox: had he not given himself the coordinates to NASA, or attempted to get Murph’s attention through ghostly actions, he would’ve never gone into space to eventually end up in the tesseract to give himself said coordinates, or create said actions. These events violate the rule of cause and effect because the effects in this instance are also the causes, and so a causal loop is created that has no beginning or end.
When Murph solves the gravity equation, she throws her papers over the space station railing and shouts “Eureka!”, saying that it’s tradition. This is a reference to the common historical practice of scientists and mathematicians shouting the phrase upon making significant discoveries. The exclamation was first attributed to Archimedes, the noted Greek scholar who, while bathing one day, realized that the volume of water an object displaces when submerged is equal to that object’s volume. Archimedes was reportedly so excited at his discovery that he took to the streets of Syracuse naked, shouting “Eureka!”, which in ancient Greek means, “I have found it!” Murph now follows in his footsteps.
We also come full circle with regard to the Dust Bowl interviews given at the beginning of the film. We see now that they’re part of a museum-like exhibit at Cooper’s former farmhouse, preserved aboard Cooper Station. And once we see the old Murph in her hospital bed, we realize that she was the first interviewee all along, inserted among Ken Burns’ actual interviews from his documentary to tie the footage to Interstellar’s premise.
Much is implied by Interstellar’s dramatic and emotional ending. Without actually showing it, we’re meant to understand that Cooper is going to meet up with Brand on Edmunds’ planet to help her prepare for the rest of humanity’s arrival. We see from the brief shot of Brand setting Edmunds’ name plate against a rock that he must’ve died waiting for people to arrive, but that his planet was the viable candidate for humanity’s next home after all. We get almost no specifics about this viability except that there’s sunlight, breathable air, and plenty of rock. Whether humanity will reach it and begin a new world isn’t known, but the uplifting music and hopeful narration from Murph (a final example of the motif where character’s words turn to narration) suggest that the imminent threat of mankind’s extinction is now over, and that their interstellar quest for survival has proven successful.
