If you have 10 or 15 minutes to spare, go read this story. It's called Light of Other Days, and was written by the late science fiction author Bob Shaw.
As a parent, I was especially struck by this story. Don't worry if you don't like science fiction. There are no rocket ships or aliens, just slow glass. Slow glass is a glass that is so dense that light takes years to pass through it. Anyway, go read the story. Let me know what you think.
Hat tip to Thingamababy.
8 minutes ago