Recent content by alexriemann

I know how to solve this problem by considering the Killing equation, namely ##\mathcal L_\xi g=0## that gives three differential equations involving the components of ##\xi=(\xi^\theta,\xi^\phi)## that can be integrated. The result I get, which I know to be true because this is a common result...

##\Delta T## is not the coordinate time difference, it is the orbital period of the photon for the observer sitting at the photon sphere. Actually, for the observer at infinity, the orbital period of the photon would be ##6\sqrt3\pi M##. Maybe ny notation wasn't clear. My guess is that I can...

I am asked to compute the orbital period of a photon, in the Scwarzschild spacetime, at the photon sphere for an observer at the same radius, ##r^\star=3M##. I have computed the result, ##\Delta T=6\pi M## where ##c=G=1## ,comparing with the proper time of an observer at infinity. However, as...