Caught a 9:40 showing of Interstellar last night, the Thursday preview before it opens wide today, and I've been turning over the black hole scene in my head all morning instead of doing actual work.
Quick disclaimer: this isn't going to be a movie review. Plenty of places for that. What I can't stop thinking about is how they actually made Gargantua, the black hole at the center of the movie, and it's a much better "tech" story than "wow pretty space movie."
Christopher Nolan brought on Kip Thorne, an actual theoretical physicist from Caltech who's spent decades on gravitational physics, as an executive producer and science consultant. Not the usual "consultant" credit where someone glances at a script and signs off. From what I've read, Thorne worked directly with the visual effects house, Double Negative, and gave them the actual equations for how light bends around a rotating black hole, gravitational lensing, the whole mess of general relativity math that nobody in a normal VFX pipeline touches. Their effects team, led by Paul Franklin, then had to build a renderer from close to scratch to handle it, because none of the standard tools (the ray tracers everybody uses for reflections and refractions in ordinary movies) are built to bend light around a warped spacetime. You're not just tracing straight lines and bouncing them off surfaces anymore, the lines themselves have to curve.
That's the part that gets me. Most "based on science" movie effects are really just concept art with a science-y label slapped on. This was closer to running an actual simulation and pointing a virtual camera at it. Whatever comes out the other end of that pipeline, wrong or right, is downstream of real equations, not an artist's guess about what looks cool. And it still ended up looking incredible, the accretion disk wrapping up and over the sphere of the event horizon like a halo instead of just a flat ring, which is apparently what actually happens when light gets bent around something that massive. I had no idea that was physically accurate until I read up on it this morning, I just assumed it was an artistic choice.
Now, a complaint, because no post here goes by without one. The sound mixing in this movie is rough. Hans Zimmer's score is enormous and gorgeous, don't get me wrong, but there were entire stretches of dialogue I flat out couldn't parse because the score and the engine noise were mixed louder than the actors. I was leaning toward the guy next to me at one point going "did you catch that." He hadn't either. For a movie this obsessed with getting the physics right, somebody really should've caught that in a sound booth before letting it into a few thousand IMAX screens. Ticket was $16.50 for the 70mm IMAX showing, plus I got fleeced another $6 on popcorn I didn't even finish because the movie is 169 minutes long and by hour two I had bigger priorities than snacks.
The render cost on something like this has to be absurd. I haven't seen exact numbers and I'm not going to make one up, but if you've ever waited on a single Blender or Maya frame to finish on a home machine you have some sense of what "physically accurate light bending, per frame, across a full feature film" means for a render farm. This is the kind of thing where the tech underneath is arguably more interesting than the marketing around it, which has mostly been "emotional dad movie, in space, wormholes." All true. But somewhere in a server room, a render farm spent who knows how many hours chewing through equations Kip Thorne handed over, just so a black hole would look the way a black hole actually looks.
Go see it on the biggest screen you can find one showing near you. Bring earplugs, or maybe don't, bring a friend who reads lips. Either way.