Effect of gravity on light ..

Ever wonder why the light which we send from a torch or a laser doesn't reach the moon and other distant things in the universe .This is completely because of influence of spacetime warping in other words gravity.

There is a variable shift in the light when it is pointed vertically towards sky , if the light we send is of high frequency then after reaching some height it's wavelength will stretch out and frequency would decrease . When the distance is very far ,the difference in frequency will be fairly enough to lose its most energy.

Light being massless how can it be effected by gravity ?

Though light is mass less particle (photons) the influence of gravity arises due to spacetime warping pulling it downwards . The velocity of light will never change ,it will always remain a constant ,this is one of the fundamental rules of special relativity.

The wavelength and frequency change themselves to make speed of light a constant.

This is the reason why we observe shifts in the light emitted by a star when it approaches or when it is moving away from us.

From Einstein's mass energy equivalence and plank's photon energy, we can equate mass of the photon to its Energy over its velocity square . The gravity acting on it leads to change in its frequency can be given by a equation.