Black Hole: Event Horizon & Light Bending (2D Cross-Section)

A 2D top-down companion to the 3D black hole simulator: the same equatorial plane, showing the event horizon, ergosphere, photon sphere and accretion disk (with its inner edge at the ISCO) resizing live as you drag the mass and spin sliders, using the real Kerr horizon, photon-sphere and Bardeen–Press–Teukolsky ISCO formulas. A fan of light rays is bent by numerically integrating the actual Schwarzschild photon-geodesic equation, so you can watch the shadow boundary — the impact parameter below which light falls in rather than escaping — form in real time.