Another favourite gimmick of ``hard SF '' authors [those who try to make their stories consistent with the known ``Laws of Physics''] is the wormhole, a sort of ``space warp'' analogous to the black hole but topologically more interesting. One can distort [ e.g. fold] a 2-D surface (like a sheet of paper) embedded in a 3-D space until two apparently distant points are ``actually'' quite close together in the higher-dimensional continuum. Then a simple puncture across both sides will provide a ``shrt cut'' and drastically change the connectedness [a formal term in the mathematics of topology, believe it or not] of space. In a similar (?) fashion, one can imagine (?) a gravitational anomaly creating a `` wormhole'' making a ``short cut'' connection between two nominally distant regions of 3-D space. Great potential for space travel, right?
Sorry. John Archibald Wheeler, who has played a major rôle in the development of all this weird Gravitation stuff, proved a long time ago that wormholes always pinch off spontaneously before anything (even a signal propagating at the speed of light!) can get through them. Of course, this fact doesn't stop Star Trek Deep Space 9 from having a lot of fun with the idea anyway.