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Interstellar Ending Explained: The Science Behind Time And Space

Interstellar Ending Explained: The Science Behind Time And Space

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From the dream worlds of Inception to the twisted revenge and illusions of The Prestige, director Christopher Nolan has always had a talent for telling unique stories.

Those stories aren’t always easy to follow, though. Nolan’s movies can be confusing, especially when they involve the physics of time, like 2014’s Interstellar.

But if you don’t get too bogged down in the science of it all, Interstellar isn’t really that tricky. This guide will explain how the movie’s timelines worked and how Matthew McConaughey was able to affect the past.

The Ending of Interstellar Explained

Interstellar is based on the idea that time isn’t linear but acts more like a loop or a Möbius strip. Towards the end of Interstellar, Matthew McConaughey’s character, Cooper, falls through a black hole and into a place called a “tesseract” where all of time is accessible to him.

Cooper later theorizes that the beings who created the tesseract and the wormhole that allows for interstellar travel are actually humans from far in the future. The only way they could exist is if humanity survives the death of Earth.

The future of humanity survives because Cooper goes to space, and Cooper goes to space because of the future humans.

Cooper crying near the end of the Interstellar movie

It’s important to think of the events of the movie as a closed circle, or even a figure eight. Whether or not time actually works this way is irrelevant; in the universe of Interstellar, it does. So, at the end of the movie, the loop Cooper is in fully reveals itself:

  • At the beginning of the movie, Cooper follows coordinates to NASA, who has discovered a wormhole by studying some gravitational anomalies
  • Cooper travels through the wormhole and (eventually) winds up in a tesseract
  • Inside the tesseract, Cooper causes the original gravitational anomalies, sends black hole data to his daughter, and sends the NASA coordinates to himself at the beginning of the film
  • Humanity is saved using the data, they eventually send the wormhole and the tesseract to Cooper’s original time, and “original” Cooper (from the start of the movie) follows the coordinates
  • Repeat

Interstellar Combines Love And Science

Cooper loves his daughter, Murphy, so much that he can find her anywhere in time within the tesseract.

The future humans may be able to see and affect all of time, but they can’t interact with specific moments. But Cooper has a very strong connection to his family, especially Murphy. He can use that connection to focus the tesseract’s power specifically on Murphy at any point.

In a less scientific way, this is also how Murphy knew to decode the ticking of her watch. She returns to her childhood bedroom for inspiration from the “ghost” that gave her messages when she was a child.

Cooper in the ending scenes of Interstellar

Finding the note she wrote decoding one of the messages in Morse code, she thinks of her father.

This memory of Morse code and her father gives her the idea that the watch Cooper left for her might be sending a Morse code message as well.

For hard sci-fi fans, Murphy’s leap of logic might be a little tough to swallow. But Interstellar is as much about the power of hope and love as it is about hard science. Another interpretation is that the hard science was simply an interesting way to tell a story that’s primarily about love and hope.

Why Doesn’t Cooper Age Throughout Interstellar?

In Interstellar, Matthew McConaughey doesn’t age as fast as his daughter because he experiences several periods of time dilation.

“Time dilation” is the difference between how large objects affect the perception of time. Remember that, according to Einstein, time is relative. As in, how you perceive it “relates” to certain factors around you.

Large objects twist time and space around them more than smaller objects. The larger the object, the more time warps. So, if you’re near an object much larger than Earth, time will pass slower for you.

When Cooper and Anne Hathaway’s character, Brand, visit the water planet, they only experience about three hours of time passing. But the water planet is near Gargantua, the black hole at the center of the movie’s plot.

Brand and Cooper in the Interstellar movie

That means time is passing much, much slower on that planet than on Earth. Or the spacecraft where their other team member, Romilly (David Gyasi), is waiting.

Cooper and Anne are experiencing time so much slower, in fact, that to everyone else, 23 years have passed. That’s roughly seven years on Earth for every hour they were on the water planet.

This time dilation happens again to Cooper and Brand when they have to fly close to Gargantua to reach the safety of another planet far away.

Flying so close to the black hole once again causes everyone else in the movie to experience many more years of time than Cooper and Brand. By the time Cooper enters then escapes the black hole, his daughter has aged so much that she’s near death.

But to Cooper, only a few minutes have gone by, and so he is still around the same age as when he left Earth in the first place.

You Don’t Have To Understand Science To Understand Interstellar

It can be hard to figure out the “why” behind the science of Interstellar, especially if your science knowledge is a little rusty. But the great thing about Nolan’s film is that you don’t really need to understand the “why” as long as you follow the “how.”

Take a fantasy setting with wizard, for instance, like Harry Potter. It’s easy to understand that certain characters can wave a wand and say some special words and boom – magic happens.

Cooper in the final scenes of Interstellar in his daughter's bedroom

But do you know why that causes magic? Do you understand the physics or universal laws that actually make that cause-and-effect action work? Of course not – it’s made-up. But that doesn’t mean you can’t understand the basic rule that wizards + wand = magic.

It’s the same for Interstellar. Maybe understanding why time relatively works the way it does in the movie is a little too complicated. But just like in a movie with magic, all you really need to know is that one specific thing causes another specific effect.

In the context of Interstellar, if you understand that being near the black hole causes Cooper to experience time slower than everyone else, and the tesseract causes him to send messages to his multiple points in time, then you understand the movie.