Question

In newton's theory of gravity light's path would not bend as it travelled near a star, because light is massless, and only particles with mass are affected by the force of gravity. Why does light's path bend around massive objects in general relativity?

a) spacetime actually bends and the light follows a curved path through it

b) it turns out that light actually has mass in general relativity

c) the speed of the light makes it curve

d) the light is reacting with the light that cannot escape black holes

Answer 1

Option (a) is correct. In general relativity, the most important relation is the Einstein equation . In words, this has the simple meaning, energy or matter causes a curvature in space-time. This theory predicts that objects follow paths called geodesics, in curved space-time. Photons feel this curvature and have to move according to it, and so light's path bend around massive objects.