Home▸Physics & Mechanics▸Relativistic Light Clock

Relativistic Light Clock

Interactive 3D light-clock simulator: watch a photon bounce between two mirrors and see, geometrically, why a clock moving relative to you ticks slower — the Pythagorean derivation of the Lorentz factor, with live proper-time vs coordinate-time readouts.

Physics & Mechanics3DModerate60 FPS

The light clock is the cleanest way to see why time dilation happens rather than just being told the formula. Two mirrors bounce a photon back and forth; in its own rest frame the photon travels straight up and down, but viewed from a frame where the clock moves sideways at speed v, the same photon must trace a longer diagonal path while still travelling at the same speed c. This simulation renders both views side by side in real 3D, derives the Lorentz factor γ = 1/√(1−β²) live from your chosen speed, and tracks proper time τ against lab-frame time t so you can watch a moving clock visibly fall behind — including real-world presets for GPS satellites and atmospheric muons, both measured cases of this exact effect.

⚙ Under the hood

Watch a photon bounce between two mirrors in a light clock and see, geometrically, why a clock moving relative to you ticks slower — the classic Pythagorean derivation of the Lorentz factor, with live proper-time vs lab-time readouts.

special relativitytime dilationLorentz factorlight clockphysics

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install