Since the speed of light through a cable is consistent, the difference is entirely in the length of its path.

WSJ: A Dive Into the Digital Deep

The length of the reference path is such that if no sample is present, the two daughter beams will be as perfectly in phase when they meet as they were when they were separated.

ECONOMIST: Microscopy

Gabbiadini forced a diving stop from Blues keeper Mark Tyler before Liddle pulled off a candidate for tackle of the season after Clarke skipped round Collett, sliding full length to scoop the ball away from the striker's path.

BBC: Posh pull it off at Wembley