To actually travel through a 'Black Hole', instead of being destroyed by it, Star God vessels enter a sort of a parallel dimension, called 'Subspace'. It is said to somehow exist outside of normal spacetime, and thus allows far greater speeds than normal FTL jumps. On the downside, you cannot enter it without a pair of 'Jump Gates', each utilizing a 'Black Hole'. Also, it is never certain when the gate can be opened and how long will the travel take.