Thread: Is Light bending possible

We know that light travels in a straight line in vaccum/air but is it possible to bend the path of light using external radiation or fields alone in air/vaccum.
Also why does refraction of light take place when it enters the boundary between materials of different refractive indices. I am told that its because velocities of light slows down/increases due to the change in the interaction with electrons with the two mediums, but what does that have to do with the actual bending of light ?

We know that light travels in a straight line in vaccum/air but is it possible to bend the path of light using external radiation or fields alone in air/vaccum.

It is possible in principle - you would need an electromagnetic field of such strength that it induces a noticable curvature in space-time within that region. The result would be gravitational light deflection.

Bear in mind though that the emphasis is on "in principle" - in practice, creating fields of the required strength is beyond our technical means by many orders of magnitude.

Also why does refraction of light take place when it enters the boundary between materials of different refractive indices

Without going into the specifics - this happens because the photons start interacting with the electrons in the material. Due to that interaction, which takes a very short but finite amount of time, the overall speed within the material is reduced.

Thanks ,but I know why speed varies. My question is how it results in the actual bending of light?

Originally Posted by kuru

Thanks ,but I know why speed varies. My question is how it results in the actual bending of light?

This boils down to the conservation of energy and momentum - at the boundary of a refractive medium the phase velocity of the wave changes, but the frequency remains constant; in order for energy and momentum to remain conserved, the propagation vector must thus change, hence the refraction.