Physicists recreate Rare Optical Illusion of near-light-speed motion in the lab

Images of the cube and sphere created by the Vienna team. At rest, the cube appears normal. When simulated at 99.9% of light speed, the sphere remains round but reveals parts of its far side. (Image credit: Hornof et al/2025)

Physicists have successfully recreated a decades-old optical illusion, first predicted in the 1950s, which occurs when an object moves close to the speed of light. The team used ultra‑fast laser pulses and high-speed cameras to demonstrate how a cube and a sphere appear rotated rather than squashed when travelling at 99.9% of the speed of light.

What Was the Illusion?

The effect is called the Terrell-Penrose effect. It challenges the intuitive assumption that objects merely shrink in the direction of motion, as described by special relativity. Instead, because light from different regions of a fast-moving object reaches the observer at slightly different times, the object appears rotated.

How the Experiment Worked?

Gated cameras were used to record a sequence of reflected light slices from the objects using a series of laser pulses. When combined, these slices produced the illusion of objects moving at near-light speed, creating the appearance of rotation without moving anything at relativistic speeds.

Why It Matters?

This laboratory simulation provides the first physical realisation of the Terrell-Penrose effect. It turns abstract physics into a visual concept. While it does not alter Einstein’s laws of relativity, it offers an effective way for scientists and the public to visualise how objects appear at extremely high speeds.

A Window into Relativity

To demonstrate the Terrell-Penrose effect, physicists employed ultra-fast lasers and high-speed cameras to reproduce the appearance of objects travelling close to the speed of light.

The relativistic visual distortions generated by this lab simulation are now easy to observe and understand. This research is valuable for teaching and for demonstrating experiments that reveal phenomena impossible to observe directly in space.