[funnygrass]

Just a thought: maybe space is not sparsely populated with bits of stars and rocks. Space is filled with a form of matter we cannot yet detect.

[ztjio]

Not matter but something is everywhere. Space isn't empty, nothing is empty, it just isn't always interactive.

https://en.wikipedia.org/wiki/Higgs_boson#Higgs_field

[dannyw]

If space is a form of matter that does not interact with any known mechanism, then it may as well as not exist.

Of course, future generations will find some sort of new matter, or some form of new interaction, but what you're saying doesn't mean anything for our world today.