General relativity liberalizes the speed limit: whereas special relativity says that no two objects can move faster than light relative to one another under any circumstances, general relativity merely insists that they can’t move faster than light relative to one another when they’re in the same place—in contrast, the galaxies speeding away from us superluminally are all very far from us. If we think of space as expanding, then we can rephrase this by saying that nothing is allowed to move faster than light through space, but space itself is free to stretch however fast it wants to.
