FTL Tech – there are two methods of getting around Einstien’s barrier. One is the Hyperlanes, massive interconnected ringgates that ‘shorten the distance’ between world by shunting travelers into an alternate dimension. However, these gates only work between fixed points.
Alternatively, ships can make use of an independent hyperdrive to much the same effect. However, these drives require precise navigational data to function properly, and even with that mishaps are more common.
The net effect of these technologies is that exploration of new star systems is best conducted as sub-light speeds, usually by unmanned probes.