A snapshot of relativistic motion: visualizing the Terrell-Penrose effect

Abstract In 1959, Roger Penrose and James Terrell independently predicted that the Lorentz contraction of fast moving objects is not visible in a snapshot photograph. Rather, the object would appear rotated. This surprising effect has never been tested experimentally. Here we demonstrate the Terrell-Penrose effect in a laboratory setting. Using ps-laser pulses and ultra-fast photography with gating times as short as 300 ps, we achieve a virtual reduction of the speed of light to less than 2 m/s, enabling the visualization of relativistically moving objects in real time. Our results comprise simulations and experimentally synthesized snapshots of a sphere and a cube, which are animated to create a slow-motion effect for velocities close to the speed of light. An extension of our method to otherwise unobservable relativistic phenomena, e. g . the famous “train” thought experiment revealing the constancy of the speed of light, appears feasible.