A wave propagating on the D¹ × S¹ bundle
A rest observer watching a massive particle. The wave always travels at speed c along its helical path on the cylinder — what changes is how that fixed speed is split between the observable base (vₓ) and the internal fiber (vθ), subject to vₓ² + vθ² = c².
At rest, the wave is pure internal rotation: the wavefronts are rings turning in place, and the internal clock runs at its maximum rate. As vₓ increases, part of the motion is diverted along x — the helix stretches, and the internal rotation (the particle's own clock) slows as vθ = c/γ. As vₓ → c the helix straightens toward the axis and the clock freezes. The bright point rides a single wavefront the whole time; the velocity triangle at the point shows the constraint in action.
Use the slider to set vₓ/c by hand, or let it ramp automatically. This is the animated form of Figure 1 in the manuscript. For the geometry behind it, see Theory.