What also surprised me is that the speed difference depending on medium is actually quite substantial. For example, glass has a refractive index of about 1.5.
So, the speed of light in glass is c/1.5 ≈ 200.000 km/s, i.e. 66% of the speed of light in vacuum.
So that got me curious, and found this
Somehow I’ve gone through decades of life without knowing this…
What also surprised me is that the speed difference depending on medium is actually quite substantial. For example, glass has a refractive index of about 1.5.
So, the speed of light in glass is c/1.5 ≈ 200.000 km/s, i.e. 66% of the speed of light in vacuum.