If scientists could create a sheet of glass with a refractive index so high that it took light months or years to travel through the glass, what kind of things do you think they could do with it?

Wow ! They could set up sheets of "slow glass" beside beautiful forests with rivers and squirrels and deer and grassy fields, and load a year of this scene into the glass, and then sell it to people who live next to dirty brick walls or ugly empty lots, and those people could install the slow glass in their windows and have beautiful scenery, until it all worked its way out of the glass.

This is a great idea ! If you possibly can, find and read the sci-fi short story "Light of Other Days" written by Bob Shaw, published in Analog Science Fiction in 1966. It's all about this exact type of glass. I read this story in 1966 and I never forgot it ! (Not yet anyway.)