Hollow Light
Sep 27, 2026 — A three.js simulator of the inside-out "cell" Earth, where the Sun sits in the middle and light bends.
What if we live on the inside of the Earth? The "cell" cosmology says the ground curves up around us, the Sun hangs in the middle, and the stars are a tiny ball at the centre. The obvious objection: then you'd look up and see Australia. The answer the model gives is that light bends. Hollow Light lets you turn that bend up and down and see what the world would look like.
Bend it to exactly 1 and something neat happens: every sightline becomes an arc through the centre, and the sky from the ground is identical to the one on an ordinary globe. Sunrises, sunsets, the Moon's phases and the stars come out right, computed from real ephemerides for any date. Turn it to 0 and the rest of the planet hangs over your head. The left view shows the cell from outside with the sunlight's actual paths; the right is what you'd see standing there. WASD walks you around the inside of the world.
It's plain three.js with a GPU ray-marcher for the "your eyes" view: each pixel's light is traced along its curved path until it hits the shell, the Sun, the Moon or the star core. The promo below is rendered straight from the simulator, frame by frame, with a synthesized soundtrack.