I wish I could find a scan of Dr. Watchstop ( http://www.amazon.com/Dr-Watchstop-Adventures-Time-Space/dp/... ),specifically the "Single Electron Proof" story based on this idea. In it, Dr. Watchstop builds a machine capable of disproving this theory by utterly destroying an electron without creating a positron. He fires it up in the second-to-last panel of the strip; the last panel, of course, is blank. Short and silly, but fairly smart and gorgeously drawn.