Spatial Rift

Tears in space. An analogy often used in Einstein's theory of general relativity is balls on a trampoline. Each ball creates a divot in the trampoline (gravity), causing nearby balls to attract each other. The heavier it is, the deeper it sinks into the trampoline.
  A Rift can be modelled as a tear in the trampoline.
  As such, anything that makes contact with a rift 'falls out of the world into oblivion'
  However, Rift-Capable Warp Drives (RCWDs) can cross rifts safely by repairing space around the drive temporarily.
  It is not known what happens to objects which fall out of the universe. It is presumed that they are annihilated with some change to the laws of physics and immediately fall apart, as all contact is lost the instant they fall out, including through machines such as QEC. Many parties have tried observing the rifts for any matter they may emit but no one has found even a single particle outside of rifts interfering with gravity. Now these groups often also try to find ways to repair space. These have seen a lot more success with the RCWD, although even those machines are extremely expensive, large, energy intensive and are only a temporary solution. Still, many sees this technology optimistically and it may be possible to use a similar technology which permanently fixes rifts. For now, they remain the single most dangerous phenomenon in the known universe to be near.