Physics / Astronomy
Black hole
Gravitational lensing: ray tracing of Schwarzschild geodesics.
What happens
A Schwarzschild black hole rendered by tracing every light ray backwards through curved spacetime. The dark disk is the shadow of captured rays, the thin bright ring hugs the photon sphere, the accretion disk shows above and below the shadow because gravity folds its far side into view, and one side blazes with Doppler beaming.
Equations used in the module
Equations ds² = −(1 − r_s/r) c² dt² + dr² / (1 − r_s/r) + r² dΩ² (Schwarzschild) r_s = 2 G M / c², photon sphere at 1.5 r_s shadow radius = √27 r_s / 2 ≈ 2.6 r_s
