Gravitational Lensing by Spinning Black Holes in Astrophysics, and in the Movie Interstellar
Interstellar is the first Hollywood movie to attempt a realistic depiction of a black hole as seen by someone nearby. To achieve this, we developed a code called DNGR (Double Negative Gravitational Renderer) to solve the equations for light-beam propagation through the curved spacetime of a spinning (Kerr) black hole, and to render IMAX-quality, rapidly changing images. Our ray-bundle techniques were crucial for achieving IMAX-quality smoothness without flickering.
This paper has four main goals: (i) to describe DNGR for physicists and CGI practitioners; (ii) to present the equations we used to map light sources to camera images via elliptical ray bundles when the camera is in arbitrary motion near a Kerr black hole; (iii) to share new insights from DNGR into gravitational lensing near a spinning black hole, as opposed to the more common studies of distant observers; and (iv) to describe how the images of the black hole Gargantua and its accretion disk in the movie *Interstellar* were generated with DNGR.
While this paper doesn’t present new astrophysical insights regarding the accretion disk, it may be pedagogically interesting for those new to the topic, and movie fans may find its discussion of *Interstellar* engaging.