Feb. 22, 2015: Interstellar wins Academy Award for Best Visual Effects

In the 2014 film Interstellar, humanity is on the precipice of extinction from drought and famine. A team of astronauts travel through a wormhole near Saturn to find a new home planet in a distant galaxy, a perilous journey in which team members explore inhospitable exoplanets and, in the film’s climax, the protagonist plunges into a black hole.

Directed by Christopher Nolan, Interstellar is one of the decade’s most notable science fiction films. The movie was nominated for five Academy Awards, and four visual effects supervisors received the prize for Best Visual Effects.

While Interstellar’s Academy Award recognized a range of technical and artistic achievements across its 700 visual effects shots, one of its most notable visuals is Gargantua, the massive black hole at the center of the film’s fictional galaxy. Grounded in theoretical physics, the efforts that went into visualizing Gargantua not only led to the creation of a new tool for black hole visualizations, its fortuitous timing — just before LIGO detected gravitational waves and a few years before the Event Horizon Telescope published the first image of a black hole — helped usher in a new era of public interest in black hole science.

The story behind Interstellar began in the mid-2000s with a short story co-written by Kip Thorne, a theoretical physicist and co-recipient of the 2017 Nobel Prize, and film producer Lynda Obst. The treatment — akin to an outline for a film script — detailed how black holes and wormholes could be featured in a story in a scientifically accurate way.

After Steven Spielberg backed out to direct another film, Nolan joined the project and, working alongside his brother and screenwriter Jonathan Nolan, rewrote much of the treatment, said Thorne. “It’s very much the Nolan brothers’ movie, but the thing that was a constant through the whole thing was the science,” Thorne said. “Within a matter of a few hours of conversation [with Chris], it became clear that we were both eager to work with each other to get this really interesting science [into the film].”

For the film’s visual effects, Nolan turned to visual effects company Double Negative (now DNEG), where Oliver James, currently DNEG’s chief scientist, had previously worked on effects for other Nolan films, including Batman Begins and Inception. James became interested in helping with the black hole and wormhole simulations for Interstellar and connected with Thorne, the film’s scientific advisor, to figure out how to translate Einstein’s general relativity equations into a film-quality visual effect.

Part of the challenge for visualizing the black hole was that the standard filmmaking technique for ray tracing — the process of modeling how light interacts with surfaces — relied on shooting rays of light at an object. But based on what had been theorized about the gravitational field of black holes by scientists, individual light rays would be pulled apart by Gargantua’s tidal forces, a visual effect that made it challenging to render a smooth image using the visual effects software.

“I remember asking [Kip] a very precise question about whether he could give us an equation of a ray of light that starts at a distant star, orbits around a black hole, and ends up in observer's eye,” James said. “That precision must have hit the right note, because 24 hours later, I received a paper that outlined a simplified version of his answer.” James used the equation to create rough early visuals, which the team then refined with Thorne’s input.

The method for generating IMAX-quality images of Gargantua used Thorne’s calculations, which integrated all the paths followed by light rays together instead of tracing the paths of individual rays. This integration allowed the team to generate high-resolution, flicker-free renderings of the black hole. Known as the Double Negative Gravitational Renderer, the team’s paper on how to render images in curved space-time is still used by computer graphics professionals and by the physics community to generate high-quality black hole visualizations, said Thorne. The team also published their methods for visualizing the film’s wormhole.

The creation of Gargantua also revealed insights about how a black hole bends, or lenses, light: It forms a complex “halo” with an accretion disc visible above, below, and in front of the black hole.

“The first time I saw the image of Gargantua with the thin accretion disc around it, I was momentarily surprised, then realized that I’ve seen this before,” said Thorne. “Jean-Pierre Luminet had done visualizations very early on in the era of what I call the golden age of black hole research — back in the 1970s — to see what a black hole with a disc around it would look like.”

Interstellar earned $681 million globally during its original release, and along with its box office haul garnered numerous news articles about the science underpinning the film, led to Library of Congress lectures and calls for its inclusion in school science lessons, and inspired a number of time dilation memes. The film’s recent return to cinemas for its 10th anniversary is now the highest-grossing IMAX re-release of all time.

Five years after Interstellar, scientists at the Event Horizon Telescope Collaboration published the first-ever image of a black hole, and then, in 2022, an image of the black hole in the center of the Milky Way. One major difference between the simulated and real images is its asymmetric shape — with the side closest to the viewer brighter while the far side is dimmer —caused by the Doppler effect. The black hole’s asymmetry can be seen in the Event Horizon images but was not included in the Gargantua simulation, said Thorne.

“It's fortuitous that the movie came out during a very fruitful period in black hole science,” added James. “LIGO got its first results, then the Event Horizon Telescope produced its images. In that sense, [our simulations] sort of anticipated those results.”

Thorne said that he hopes to see more complex astrophysics featured in Hollywood films in the future, particularly phenomena like colliding black holes and spaghettification. “Space-time dynamics is really a huge playground for both astrophysicists and filmmakers that goes so far beyond what you see in Interstellar,” he said.

For James, one of the biggest impacts of the work beyond the film itself is “the way that it changed public perception of what a black hole might look like,” shifting away from how previous depictions of black holes had been akin to “vague whirlpools in space,” he said.

James recalled that, while working on Interstellar, he thought the wormhole would end up being the visual effects star. “No one really talks about the wormhole now,” he said. “My conclusion is that, by doing the black hole with such scientific rigor, it created its own life — a little story within the film that took [the black hole] outside the boundaries of the movie.”