Questionable Questing

trace cause and effect backwards or something, and thus reconstruct past scenes as streamed video data. Using the GPS, camera, and instrumentation of a mobile device for reference, and providing a particular date (In AD - years BC are represented as negative numbers), it locates what you would have seen and heard from your device's perspective if you were there, looking that way, then.

Of course, it doesn't adjust your represented position for the past state of the continents, or of the sea level if you're at sea. If you went to the dogger banks, you'd be WAAAY above what the machine would be showing as the land if you put in a time when doggerland was around.

Very voyeuristic, and frighteningly potent as just...normal surveillance tech for modern contexts.

Ah, the good old Principle of Determinism. Weather forecasts are, of course, based on pretty much the same idea.

I seem to recall hearing about a story along those lines a while back; it focused on the voyeurism angle, as people promptly start using it on the *recent* past.

Fundamentally, there are thousands of different front ends the machine could use: a mobile app that streams the location data continuously in exchange for a continuous stream of the past is just one of them. You could create a system that saves all of your starting points for past readings, and which can send a copy of that starting point to the mainframe to replay a viewing starting from the same point in time.