Question: Is there an actual way to change the speed of light?

Parnika Gupta answered on 5 Nov 2020:

1. First your textbook knowledge – Well, when the light goes from air to any other material with a different refractive index, it experiences either an increase or decrease in speed. This is called refraction.
Light changes speed as it passes from one medium to another. The frequency of light does not change as it refracts. The refractive index of a material is a measure of the change in the speed of light as it passes from a vacuum (or air as an approximation) into the material.
2. That is a very interesting question so some further space tid-bit! Many researchers have actually claimed that the speed of light changes in space because the composition of space includes many particles that are there for a moment, and disappear the next moment, so the collision of these particles with photons (light particles ) might change the speed of light. This is right now, a hypothesis. You keep thinking on how we can prove it.
On Earth though, it is very difficult to change the speed of light as you would require some accelerating force, energy that is high enough to change the speed of light in vacuum.