Effect of gravity on light
Since we can think of light as having a mass , relative to an observer in an accelerated lift, light will curve downwards [ see Figure 5.5 ]. Therefore by the principle of equivalence, light will also be bent in a gravitational field [ examples: light deflection due to the sun's gravitational field; observed during a total solar eclipse. Lensing of cosmological sources. ].
Figure 5.5: The bending of light