Ectoplasm: 3D Colloidal Light Scattering

This simulation renders a full 3D jar of "ectoplasm" — the classic mastic-resin-in-water colloid demonstration, dressed up for Halloween — as a real volume of drifting colloidal particles lit by a repositionable light source in 3D space. Orbit the camera freely around the glass jar while dragging the azimuth, elevation and distance sliders to sweep the light source anywhere around it, and watch a true volumetric beam of additively-blended scattering sprites trace a glowing cone through the fluid wherever particle density is high enough. The particle-size slider is the core physics knob: dial particles down toward true molecular scale and the beam goes dark exactly as a real solution would, then push them up into the colloidal range (roughly 1 micron) and the Tyndall glow switches on, brightening further as concentration rises. Re-pour to reseed a fresh, randomized particle field.