Mass bending space makes me think there's another "side" to space Perhaps I'm not understanding space curvature very well, but how could it curve if the universe, or space, is an open system? If mass is bending it, this makes me believe the universe is a limited and closed system. In other words, space is some kind of elastic boundary for matter. And this doesn't make sense because I thought space was a type of property without boundaries. Edit: Or is it simply local space curvature? Silly me...if that's what it is.