StartsWithABang writes You know the fundamental principle of special relativity: nothing can move faster than the speed of light. But space itself? That's not a "thing" in the conventional sense. Two years after coming up with special relativity, Einstein devised the equivalence principle, and thus began the development of general relativity, where space itself would have properties that changed over time, responding to changes in matter and energy. This includes the ability for it to expand, even faster than the speed of light, if the conditions are right.