Behold the void, realize it as thine own intellect, blissful and shining.
Tibetian Book of the Dead.
Space is the concept of distance between objects. Void is the concept of space without objects.
E=mc2 implies that space is something more than simply distance. You see, spacetime is a fabric, and that fabric permeates the Universe.
If energy can relate to matter as a function of space and time, then space AND time are SOMETHING, not simply a void intermingled with objects. And as Einstein stated, General Relativity cannot exist without the ether (or Aether)...