[dleviwing]

Nobody;
There is Relativity that is just the perceptual geometry of space as if it were devoid of substance and there is Relativity that is the substance of space that warps and bends. Think of space as the atmosphere of the universe; it is the medium of the electromagnetic state of fundamental substance and is sustained by these vibrations; in short, it is just a less dense state of fundamental matter. Novices tend to think space infers a volume devoid of any physical entities; that’s what it used to mean before Einstein redefined it. You may wish to use “void” to refer to that kind of space these days.

BTW: what we call space is made of the same stuff that we call matter.