Acceleration is a change in velocity. Velocity is a measurement of direction and speed. The website you pointed me to says "The Einstein Theory correctly predicted the amount of the deflection of starlight". Is this acceleration?
If light approaches a black hole will it accelerate? I think this question ties in with whether light has mass or not. Does light have mass? It seems accepted that light has momentum, but this is not consistent with saying that photons are mass-less (momentum=mass*volume). Could someone clear...