[EvaH (OP)]

Andrew wants to know:

Most books on lenses attribute the bending of a light beam by a medium (glass etc) to be related to the difference in the refractive indices, and the angle of incidence. Raytracing is an illustration of these theoretical concepts. The claim is made that this bending relates to slowing of the speed of the light. Given the speed of light seem the be an absolute value in vacuum, is there scientific proof that the speed actually reduces?

What do you think?

[Janus]

Andrew wants to know:

Most books on lenses attribute the bending of a light beam by a medium (glass etc) to be related to the difference in the refractive indices, and the angle of incidence. Raytracing is an illustration of these theoretical concepts. The claim is made that this bending relates to slowing of the speed of the light. Given the speed of light seem the be an absolute value in vacuum, is there scientific proof that the speed actually reduces?

What do you think?

Experiments which showed that light travels at different speeds through different mediums were successively performed way back in the mid 1800s.

[evan_au]

In the following thread, Bored Chemist proves that light slows down in water using home-handyman equipment (a laser rangefinder):
See: https://www.thenakedscientists.com/forum/index.php?topic=80810.0
Look at « Reply #5 on: 24/10/2020 17:15:11 »