Stephen Hawking did a lot to popularize information about black holes, but he never saw one. He began his work in 1965 and died in 2018. Imagine that: over fifty years studying something that he never even had the opportunity to look at. From repeated mathematical calculations over the course of a century, Einstein’s theory of General Relativity, and observational data best explained by a dark, supermassive collapsed star, we had substantial evidence of black holes’ presence, but visual detection eluded us.
In 2014, director Christopher Nolan released Interstellar, his ninth film. Like all Nolan films, visual spectacle was a chief selling point. In the story, a team of astronauts find themselves approaching a supermassive black hole as they search for a way to save a dying Earth. From the beginning, Nolan recruited astrophysicist Kip Thorne to develop the concept, and he agreed, on one condition: scientific accuracy would not be sacrificed in the name of cinema.
Dr. Thorne worked with the visual effects team to create a simulation of the black hole. Using pages and pages of deeply-sourced academic writing to guide their work, they entered real astronomical data and calculations into their program and faithfully based their rendered computer model for the film on the result. The final effect totaled 800 terabytes of data, with some individual frames taking up to 100 hours to render.
Based on his research, Dr. Thorne had theorized since 1974 that black holes have a feature called an accretion disk. A cloud of diffuse matter orbits them in a flat disk, pulled gradually towards the center. As it approaches, gravity and friction compress the material until it emits heat and light. Since black holes emit no light (gravity within the black hole is too strong for even light waves to escape), the accretion disk acts as a highlighted border, outlining the silhouette of the event horizon (the all-black “point of no return” shell surrounding the singularity at the center).
In 1936, Einstein predicted another visible phenomenon around a black hole: gravitational lensing. Light from objects behind a black hole is warped by its gravity, bending around until seen from the front. These two phenomena make up the glowing halo around a black hole: the orbiting accretion disk, seen from the front and back side of the hole simultaneously, blended with stretched and deformed light from the stars behind it.
The Interstellar effects team created the most detailed and realistic model ever of a black hole. The effect was breathtaking, and Kip Thorne was keen to study it. They published three academic papers about the model: two describing new insights on accretion disks and gravitational lensing (the halo effect was actually a new discovery), and one detailing the innovative computer effects techniques used in the process.
There remained more to discover, though. The model visualized the data in a spectacularly useful way, but we still lacked the opportunity to compare it to direct visual evidence of black holes — but just five years later, we did. In 2019, the European Space Agency’s Event Horizon Telescope team shared the first-ever picture of a supermassive black hole, designated M87*. The subject lies at the center of the giant, elliptical Messier 87 galaxy, over 53 million light years away. It was captured by taking over most of the millimeter wave telescopes worldwide for five nights to effectively create an Earth-sized telescope — the only tool powerful enough to view across such vast distances in any detail.
The resemblance to the Interstellar team’s work is striking, validating Dr. Thorne’s data. The production’s dedication to scientific accuracy allowed the world to preview one of the most astounding astronomical discoveries of the modern age half a decade early. By attending the red carpet premiere, Dr. Hawking was able to enjoy that same preview before he passed away.
Just three years later, in 2022, the Event Horizon team released another picture, this time of Sagittarius A*, the supermassive black hole at the center of our own Milky Way galaxy. Again, the evidence from this discovery validated a century of theory, from Einstein’s General Relativity to the Interstellar team’s incredible simulation. It was a victory for astrophysics, cosmology, and computer effects.
Isn’t it amazing how people can build off each other’s work? We look at the discoveries of our peers and predecessors and ask new questions, try new methods. Then the same is done to our results: others correct our errors, plug in gaps, and make improvements. Amazingly, the people involved need not even live in the same place or even the same time. Through this process, we bring our collective understanding closer to the truth.
Science is a game of incremental improvements — just like business, art, and athletics. Professionals from different fields approach problems in different ways, bringing new perspectives. An astrophysicist was able to take a fresh look at an old mystery when he involved a team of Hollywood special effects artists. Meanwhile, another group of scientists used a powerful new tool, less than ten years old, to view something magnificent for the first time. Together, their work validated over a century of research.
The ability to collaborate is humanity’s greatest strength. Never take it for granted, never underestimate it, and never be afraid to ask for a new perspective.
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Watch this featurette about creating the Interstellar black hole model to hear more directly from the people involved in its creation. It also includes some clips from the movie showing the effect in action.
