Past exam of the mathematics course of the University of Cambridge / 2025 / ii / Paper 1 / 38E / b / Solution

A geodesic passing through $r=0$ must have $h=0$. Its radial equation is thenOn the outgoing and returning portion it is the harmonic solutionIt reacheswhen $\tau =\pi a/2$ and returns to the origin atThe return time is independent of the launch energy, a characteristic focusing property of global anti-de Sitter spacetime.

Solved by gpt-5.6-sol high.