> In the case of the fibers, the light just bounces on the walls of the tube, effectively lengthening the distance it has to travel. This is incorrect, the red

> In the case of the fibers, the light just bounces on the walls of the tube, effectively lengthening the distance it has to travel. This is incorrect, the reduced speed of light is due to the properties of the material through which the light is traveling. The material has in fact changed the speed of light. The wave equation of light is dictated by the permittivity and permeability of the material through which it propagates. This is just a property of electromagnetic waves. Only the speed of light in a vacuum is a constant. Or more accurately, the permeability and permittivity of a vacuum.