If you've seen a diagram of an atom, with the electrons floating around and stuff, you see that its mostly just space. And the electrons, nutrons, and protons aren't actually blue, red, and yellow balls. Their just energy, just more space really.
So basically everything that exists is space. We experience it and so, to us, it exists. But if we didn't experience it, it wouldn't.
I suppose I'm saying everything exists if you see it that way. Otherwise you just see empty space. Something like that.
I am so going to be burned for this XD