When the speed of light is normally too fast to perceive, the creators of Relativity Park turned it into a walkable scale. In this simulator, the fundamental constant c is set to 5 kilometres per hour — roughly a brisk walking speed. As the observer moves, the scene displays physically accurate relativistic phenomena that would normally require velocities near the speed of light to become noticeable.
Walking forward compresses the view in the direction of motion (aberration) and blueshifts light from ahead, while looking backward stretches the field of view and redshifts rearward light. A timer labelled "Your watch" tracks proper time, and a separate "World clock" shows coordinate time, making time dilation visible. The ground and moving props — a Ferris wheel, carousel, and shuttle — are rendered with length contraction and Terrell rotation, so their shapes and apparent positions change as the observer accelerates.
This image illustrates the simulator's rendering of relativistic effects such as aberration, Doppler shift, and Terrell rotation as described in the article.
Controls let the user accelerate with W A S D keys, look with the mouse, stop motion with Space, and toggle effects such as light‑travel delay, aberration & contraction, Doppler colour, relativistic beaming, and ground detail. A settings panel adjusts exposure, beaming exponent, render scale, and an eye‑adaptation model that averages brightness over time.
The project, built by Dmitry Brant, is hosted on GitHub as the repository dbrant/relativity, which provides the source code and live-demo instructions for running the simulator locally.
By reducing c to a human scale, the demo makes it possible to observe effects that are usually hidden at relativistic speeds, offering an intuitive feel for how Lorentz transformations alter space, time, and colour when velocity becomes a significant fraction of light.