Hello all, Would like to get some feed-back on some questions I had about special/general relativity and a thought experiment. In the case of gravitational lensing, an obvious case being the earth is lined up with the sun which is lined up with a distant star. From earth the star is seen because of gravitational lensing. The path of a photon is increased by the curvature of the sun compared to the path it would take if the sun was not present. Is it possible to say that light has been slowed down by the curvature created by the sun? Can this be interpreted as (length contraction)/(time dilation) = c? Suppose the sun was displaced in space and it's mass was altered such that the earth received direct light and light that curved around the sun. Two photons left the distant star at the same time and at such angles that one photon traveled in a straight line to earth and the other had to curve around the sun. The direct light would clearly hit the earth first in time. Would this violate special relativity? Al so, is the constant speed of light a postulate of special relativity or can it be "proven"?