Relativity Park: a 3D website where light travels at 5 km/h so walking shows relativity
mcleavey · x · 2026-09-14
Relativity Park is a 3D web experiment that sets the speed of light to 5 km/h — a brisk walk — letting you experience special relativity simply by moving through a park with WASD keys.
Toggleable effects include:
- L: light-travel delay
- G: aberration and length contraction (lengths ahead squeeze)
- C: Doppler shift — blueshift ahead, redshift behind, visible transverse Doppler
- B: relativistic beaming
The HUD live-tracks β, the Lorentz factor γ, and the growing gap between your watch and the world clock (Terrell rotation, time dilation). A rare interactive physics demo that beats any textbook diagram.
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