I hope this is an easy question. Assume if you will there's a spark somewhere in a fairly small volume -- say in a given cubic foot. If I'm allowed to put some form of omni sensor (crude phrasing to mean it can detect amplitude but not direction with any precision --- PMT, photodiode, whatever) just by observing the time differences among them I should be able to determine of the spark. The question is, with what precision? Are 10s of picoseconds resolution reasonable? I started my engineering career when transistors came in bottles called 12AU7s that glowed in the dark, and admit to being dated.