Adding to the fun - The light is still going the same speed within the medium, but it’s bumping into more things. Those collisions divert the light, lengthening the distance it travels through something like 1 cm of glass vs 1 cm in a vacuum. It changes the time it takes to travel through glass rather than the speed at which the light is moving.
At least that’s what I remember from a YouTube video.
Adding to the fun - The light is still going the same speed within the medium, but it’s bumping into more things. Those collisions divert the light, lengthening the distance it travels through something like 1 cm of glass vs 1 cm in a vacuum. It changes the time it takes to travel through glass rather than the speed at which the light is moving.
At least that’s what I remember from a YouTube video.
Probably the Youtube video in question
Yes that’s it! Thanks for the link!!