Bob Shaw's "Light of Other Days" aka "Slow Glass" (short story, science fiction): Improving the view you see from your window!
I'd tucked away a short comment on this story in Hartwell's "Ascent of Wonder" post, but was struck again by similarity of its "slow glass" with the time travel gates in Chiang's "The Merchant & the Alchemist's Gate" when I saw this year's Nebula winners' list yesterday.
In both cases, you have a sort of thin sheet through which things pass & come out in a different time. "Slow glass" only passes radiation; Chiang's gate passes both matter & radiation.
Both permit transfer in either direction, but with differences. Each side of slow glass shows you past seen by other side - how far back depends on specifications of glass. Chiang's gate moves you forward in time in one direction, & back in the other.
The most interesting thing about this story is: "slow glass" is a realistic gadget, even if we don't have any idea of how to build one today. Plot itself is not bad, but not great either; this story gets listed among classics because of its description of the gadget, & its possible applications.
What is "slow glass"? It looks like ordinary glass sheets that go into your windows. But it drastically slows down the passage of light through it; light takes years to pass through the sheet of glass - depending on specs.
What does this mean? You take a newly made glass sheet, & place in near a lake or in a forest. Let it stay there for 2 years - assuming that is how long the light takes to pass through it. At the end of the time, the glass effectively has memory of the place - & in a far more realistic manner than any video shoot. A bird swooping down, some dears coming for a drink, ... whatever happens on the scene is recorded.
Now sell this glass to a city dweller with a window overlooking a neighbor's kitchen. What have you got? The lovely lake view in your window - for next 2 years. At the end of this time, 2 year old local light will begin penetrating so you will want to replace it again.
Fact sheet.First published: Analog, August 1966.
Download full text from Internet Archive.
Nominated for Nebula Award 1966 in short story category.
Nominated for Hugo Award 1967 in short story category.
Included in Ellen Datlow's Sci Fiction classics.