Parallel light rays gravitationally lensed by a Schwarzschild black hole, deflected near the photon sphere
This program computes the trajectories of null geodesics around a Schwarzschild black hole, visualized by projecting off the time direction into a spacelike slice outside the event horizon. A collection of initially parallel light rays is sent toward the black hole, demonstrating the gravitational lensing effect: rays passing close to the photon sphere at r=3M are strongly deflected.
The menu at the upper right allows one to control the thickness of the original collection of geodesics, as well as their closest approach to the photon sphere. Controls: Click and drag to orbit, scroll to zoom.
