User blog comment:The Milkman/The Writing of the Ending/@comment-5144441-20120601071637/@comment-4835791-20120601132657

A relay it's not a teleport or a wormhole it's just a space were the objects weight is reduced to zero so they can achieve FTL and travel long distances in much less time than conventional FTL. So when a ship is inside the relay it takes some time to cross the space between relays.