Thread: If photons in motion have no mass, then how can gravity bend light ?

Would like to see some reference for any explanations. Either light doesn't bend or moving photons DO have mass. One of them must be wrong, yes?

This is the classic question addressed by Einstein when trying to find a way to verify his Theory of Relativity that proposes that gravity distorts the fabric of time-space rather than acting like a simple Newtonian force which is inversely proportional to distance. The light must still travel through space-time and so even though it is not accelerated by the gravity as an object with mass would be, its direction is still deflected by the distortion of space-time due to the gravitational field. Einstein's Theory was a departure from Newtonian Laws of Motion which predicted that just as you have stated, since the photons had no mass, they would be undeflected by gravity. Proof of the deflection of starlight by the gravitational field of the Sun measured during a total solar eclipse was the first definitive verification of Einstein's revolutionary Theory.