Friedman-Lemaitre-Robertson-Walker (FLRW) metric - Universe in Problems
SOLVED: The Robertson-Walker metric is given by ds^2 = -dt^2 + a^2(dr^2/(1-kr^2) + r^2(dθ^2 + sin^2θdφ^2)), where k = 0, +1, or -1, depending on whether the three-dimensional space has zero, positive,