Physics
Gravitational Lensing (Einstein Ring)
α = 4GM / (c²b)
A background source lensed by a foreground mass focuses into a ring of light whose radius breathes as the alignment shifts.
Computed & rendered in pure C# on the frozen OnlyCSharp 1.8 library — animation baked to GIF with the library's own
Gif encoder (no GPU, no ffmpeg, no external packages).