Thread:Ghelæ/@comment-5080468-20170729213650/@comment-47205-20170730165413

While there is some connection between a few forms of fictionverse FTL (namely warp drives, Krasnikov tubes, and traversible wormholes) and the FTL solutions of general relativity, it's important that we do still tie them to a privileged frame of reference - a role filled by hyperspace - because otherwise relativity of simultaneity could be exploited to allow for time travel to the past. Hyperspace then grants us additional freedom to have other forms of FTL beyond that of four-dimensional GR.

The advantage of Krasnikov tubes is that things can travel through them without hyperdrives of their own. The disadvantages are that movement is restricted to between locations fixed by the endpoints of the tubes, and that tubes are physical structures requiring a huge amount of material to build.