Spacetime -- it warps, it curves, but can't expand?? I have a problem understanding this. The general consensus of respected posters in cosmology is that space (and I assume spacetime) is nothing, therefore it cannot expand. Distances just increase. On the other hand, when it comes to gravity and GR, spacetime is no longer nothing -- it warps and curves and holds giant bodies in place. These seem like powerful and real physical properties, yet when it comes to the expansion of the universe it is apparently heretical to suggest that spacetime can have properties which can contribute to or cause the expansion. Is there a layman's explanation for why we can assign powerful properties to spacetime in one theory and dismiss the possibility that it has any effect in another theory?