English: This figure depicts a null geodesic arc in the Born chart for Minkowski spacetime. In this chart, the world lines of Langevin observers, who ride on disks rotating with constant angular velocity, appear as vertical lines. The figure shows the world lines (blue vertical lines) of two Langevin observers who are riding on a rotating ring (the rim of a disk, if you like). The axis of cylindrical symmetry is shown as a green vertical line. The cylinder represents a surface of constant radius. The z coordinate is inessential and has been suppressed from this figure.

This particular null geodesic arc represents the world line of a radar blip sent from one ring-riding observer to the other. As the figure shows, this null geodesic (which appears as a straight line in the cylindrical chart) appears in the Born chart to be bent toward the center.

This figure was created by User:Hillman using Maple to export a jpg image and eog to convert this to a png image.