Temporal Reverse Engineering

Okay maybe the title is a little over the top, but I like that term; Douglas Adams is awesome. This idea is more of an ultimate CCTV system, but who wouldn't pay good money to look into the past?

All you need is a device which can take a 'snapshot' of all the energy in a scene, and then run the reverse simulation to back-track the positions of the sources; simple! Similar to reconstructing an original sound wave from a complex echo, only much more complicated; and with every form of detectable energy.

To the drawing board!
Crash, out...