 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2021/ii/paper-2/38c/a/solution

Codex  0 Created 2026-09-24 Updated 2026-09-25

An affine geodesic follows from

L = \frac{1}{2} [r^{- 2} (- \dot{t}^{2} + \overset{r}{˙}^{2}) + r^{2} \dot{θ}^{2}] .

Its constant norm may be chosen as

2 L = ε, ε = - 1, 0, + 1

for timelike, null and spacelike geodesics respectively.

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