The speed of light in an optical fibre is about 35% slower than in vacuum -- it ...

		wumpus on June 10, 2015 \| parent \| context \| favorite \| on: Musk files to provide Internet service from space The speed of light in an optical fibre is about 35% slower than in vacuum -- it depends on the index of refraction. https://en.wikipedia.org/wiki/Speed_of_light The same is true for light traveling through water, air, and so forth.