So the Speed of Light Never Changes?

Wrong!

This only holds up in free space.  The speed of light slows down when it goes through matter.  This includes glass, which is why fibre optic researchers care about calculating the impact glass has on the speed of light.

How fast does light travel through a fibre optic cable?

Light travels slower through fibre optic cables than free space.

Researchers are getting closer to building fibre optic capabilities that approach the speed of light.  The ongoing estimate is that list travels 31% slower in fibre optics than free space.

So watch this space for future developments!

Read the full article here https://shorturl.at/lmnJR.