Some individual frames took up to 100 hours to render, the computation overtaxed by the bendy bits of distortion caused by an Einsteinian effect called gravitational lensing. In the end the movie brushed up against 800 terabytes of data. I thought we might cross the petabyte threshold on this one, von Tunzelmann says.
Chris really wanted us to sell the idea that the black hole is spherical, Franklin says. I said, You know, it's going to look like a disk. The only thing you can see is the way it warps starlight. Then Franklin started reading about accretion disks, agglomerations of matter that orbit some black holes. Franklin figured that he could use this ring of orbiting detritus to define the sphere.
Von Tunzelmann tried a tricky demo. She generated a flat, multicolored ringa stand-in for the accretion diskand positioned it around their spinning black hole. Something very, very weird happened. We found that warping space around the black hole also warps the accretion disk, Franklin says. So rather than looking like Saturn's rings around a black sphere, the light creates this extraordinary halo.
That's what led Thorne to his why, of course moment when he first saw the final effect. The Double Negative team thought it must be a bug in the renderer. But Thorne realized that they had correctly modeled a phenomenon inherent in the math he'd supplied.
Still, no one knew exactly what a black hole would look like until they actually built one. Light, temporarily trapped around the black hole, produced an unexpectedly complex fingerprint pattern near the black hole's shadow. And the glowing accretion disk appeared above the black hole, below the black hole, and in front of it. I never expected that, Thorne says. Eugénie just did the simulations and said, Hey, this is what I got. It was just amazing.
In the end, Nolan got elegant images that advance the story. Thorne got a movie that teaches a mass audience some real, accurate science. But he also got something he didn't expect: a scientific discovery. This is our observational data, he says of the movie's visualizations. That's the way nature behaves. Period. Thorne says he can get at least two published articles out of it.
