A relativistic simulator in python

Department of Physics, University of Bucharest, Atomistilor 405, Magurele, 077125, Ifov, Romania

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Published online: 15 April 2026

Abstract

We present a 3D relativistic simulator developed using the Ursina Engine in Python, inspired by sandbox-style games. The simulator incorporates core principles of special relativity—such as time dilation, length contraction, and the relativistic Doppler effect. It is designed as a first person perspective game, where both the player and the surrounding objects can move, which allows phenomena as the Terrell rotation to be illustrated in an intuitive manner. The simulator features multiple scenarios, each of them illustrating a different example. The main elements of theory on which the simulator is based are presented in the documentation that accompanies each scenario. Our simulator can serve as an educational tool for university or high school students. The software is modular and designed for extensibility, allowing future integration of other effects. Another key aspect is the simplicity of the implementation, which facilitates extension and modification. The rich documentation that accompanies the code allows for easy understanding of both the program and the physics behind it. This also creates the possibility of using it as a template for other projects and allows users to experiment with the underlying physics by directly modifying the code. This would contribute to cementing the students' understanding of the special theory of relativity.