A new interactive visualization called Light is slow here imagines a world where the speed of light is just 5 km/h — a brisk walk. The project, shared on Hacker News, lets users experience relativistic effects like length contraction, time dilation, and Terrell rotation using everyday movement. Controls include Arrows/WASD to accelerate, Mouse to look around, Space to stop, and keys L, G, C, B to toggle effects or R to reset.

The simulation also demonstrates the Doppler effect, with objects in front blueshifted, objects behind redshifted, and transverse Doppler effects visible on moving objects. The creator aimed to help people intuitively grasp relativistic physics by scaling light speed down to human-paced movement. The project is open for interaction and feedback on the Hacker News discussion thread.