This simulation demonstrates how we observe objects moving at speeds approaching the speed of light. The expanding circles represent light waves emanating from a moving source, with each circle's color (hue) encoding the state of the source at the moment of emission.

As you watch the simulation, imagine the circle growth speed as the speed of light constant (c). The moving red dot is the source, emitting light waves (circles) at regular intervals. The cyan dot is you, the observer.

Notice how the waves reach you not in the order they were emitted, but in the order dictated by their travel time. The colors tell you the history—which moment of the source's journey you're actually seeing. When waves intersect your position, a "ghost" appears, marking a moment of perception.

This illustrates why fast-moving objects appear distorted in time and space: you're not seeing where they are, but where they were when light left them. Adjust the speeds to explore how relativistic effects transform our perception of reality, stretching time and compressing space in the dance between emission and observation.