Homework Statement
I'm given the metric for Einstein's universe,
ds2 = c2dt2 - dr2/(1 - kr2) - r2d(theta)2 - r2sin2(theta)d(phi)2
and asked to find the null geodesic equations and show that in the plane theta=\pi/2, the curves satisfy the equation:
(dr/d(phi))2 = r2(1-kr2)(mr2-1)
where m is a...