Matter is the term for elimentary particles - no one knows what matter is or what size it is.
The Elimentary Particle used to be Sand
Then it became the Atom
Then it became the Neutron, Electron, Proton
Then it became the Quark
Who knows what it will become tomorrow?
Who knows what it will become in a thousand years?
There can be no end to space.
Anyone who quotes Time as the fourth dimension clearly hasn't thought it through.
Agnostic means to not know.
No-one will or can ever know how far space goes or who is in charge, because it is all impossible.
Infinity is impossible.
You're are basing your opinion on scientific fact.
Scientific fact does not exist.
The world was once flat according to scientific fact.
Have you ever considered Agnosticism.