Interstellar is a critically acclaimed sci-fi film directed by Christopher Nolan. The film is set in a dystopian future where humanity tries to survive on a planet struggling to sustain any life at all, a topic that’s even more significant today. A team of astronauts recruits former NASA pilot Cooper (Matthew McConaughey) to join them to go through a wormhole in search of a potential new home for the human race. Interstellar was praised not only for its stunning visual effects but also for its scientific accuracy throughout the film, particularly for its portrayal of theoretical astrophysics. The film was nominated for a total of five Academy Awards, winning the award for Best Visual Effects.
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Updated May 22, 2023: If you’re a fan of Interstellar, then you’ll be happy to know this article has been updated by Grayson Uckele with additional material.

One of the reasons Interstellar was so groundbreaking was that it accurately depicted the concept of time and space, showing the realities of time relativity. Considering the fact that many sci-fi experts consider Interstellar to be the greatest sci-fi film of all time, even above 2001: A Space Odyssey, it makes sense that there are aspects of the film that may be confusing. Something that threw many people for a loop was the ending of the film. It takes a hard left turn and winds up becoming a true sci-fi dream, but what exactly does Interstellar’s ending mean?

Interstellar’s Ending: What Happened?

Paramount Pictures

In the third act of Interstellar, it’s revealed that the Endurance ship does not have enough fuel to get back to Earth and that a black hole poses a great threat to the team. In order to save humanity from extinction, Cooper sacrifices himself alongside his robotic companion TARS to shed weight so that his colleague Amelia Brand (Anne Hathaway) can complete the mission on her own to the planet Edmunds. Cooper thus drifts into the black hole and must escape the collapsing ship around him. However, before he can, Cooper enters a “tesseract,” a projection of a human’s life from the fifth dimension, simplified for Cooper’s understanding.

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This space is a physical representation of his daughter Murphy’s bookshelf, with which he tries to communicate with her as he watches her life unfold from the fifth dimension. Cooper is able to relay important information to Murphy (Jessica Chastain), which, in turn, helps her save humanity from extinction. When Cooper is ejected from the tesseract, he is found and returned to a colony of Earth, only to discover that 90 years of Earth-time has passed since he left, though he has barely aged. Cooper reunites with his elderly daughter Murphy Ellen Burstyn), who tells him to seek out Brand, who may have colonized elsewhere, which is seen to have been a success.

Interstellar’s Tesseract

Paramount Pictures

Arguably the most unique and outstanding scene, both visually and scientifically, is the one within the tesseract. This fifth-dimension interpretation has been described as not only scientifically accurate to what could happen should someone enter a black hole, per Gizmodo. It also allows the audience to better understand the concept of space-time. Throughout the film, the inventors of the tesseract are referred to as “they,” and it’s later revealed that “they” are human descendants who have come to exist as fifth-dimensional beings, divorced from the laws of the fourth dimension – one of those laws being time.

While it may seem like Cooper wound up in the tesseract at the hands of extraterrestrials, the reality is that future humans sent Cooper through the tesseract to save the future of the human race. These humans built this space so that Cooper would understand what was happening and would convey vital information to Murphy through Morse code through her bookshelf.

The tesseract also raises the question of Nolan’s use of causal loops throughout the film, the sci-fi genre’s favorite plot device. The tesseract scene reveals that Cooper has been Murphy’s ghost all along, and therefore he’s the reason behind his journey through space. Through the tesseract, Cooper is able to arrange the coordinates to NASA’s secret base in dust from the storm at the beginning of the film. If it weren’t for Murphy’s ghost, then Cooper would have never known how to get to NASA, and he would have never been able to join the mission. How is Cooper able to send the coordinates to himself without initial knowledge of the base? Through the causal loop, of course. And it’s not the only causal loop in the film, the fifth-dimensional future humans invented the tesseract for Cooper to send Murphy life-saving messages through in order to save the human race. The causal loop, though confusing, makes it possible for future humans to essentially save themselves.

What Does Interstellar’s Ending Mean?

Paramount Pictures

While Interstellar’s ending is mind-blowing and somewhat difficult to understand, what many viewers have wondered is: what exactly does the ending mean? Interstellar not only explores the aspects of space and time, as well as the fifth dimension, but the plot covers the potentially disastrous results of climate change, which could lead to environmental catastrophe, making the surface of the Earth uninhabitable. This sends a deep-seated message to the viewers that climate change is a real problem that could bring unimaginable consequences if it goes unchecked.

Related: How Interstellar Has Become One of Christopher Nolan’s Most Beloved Movies

One notable element at the heart of Interstellar is love. While the movie is very interested in accurate scientific depiction, it also hangs much of its ending on the abstract idea of love. Earlier in the film, Hathaway’s character Brandt says, “Love is the one thing we’re capable of perceiving that transcends dimensions of time and space.” which is made literally in the film. A father’s love for his daughter and a daughter’s love for her father is the key to saving humanity. Separated by lightyears, their love for one another saves both of them. This is a rather human outlook for a movie that some may see as realistically cold. Love has ripple effects that are felt across time and can alter the course of history.