Spacetime is a thing, they are intertwined. That's like asking where does time flow to, infinity just like space. I think of reality as a superset of spacetime, matter,energy,etc... could there be other things or universes in reality? I don't know but put simply I understand it to mean the distance relative to a refernce frame expands.
My question to people who actually know this subject: has 'c' been proven to be constant, resisting expansion? The speed of light/causality might be affected if time also expanded along with space? Or how can space expand without time expanding given its relationship with time?
Some day we might create the necessary mathematics to explore the answer space of these questions (and related ones). We don't yet have the technology, so to speak, to "think" of this.
My question to people who actually know this subject: has 'c' been proven to be constant, resisting expansion? The speed of light/causality might be affected if time also expanded along with space? Or how can space expand without time expanding given its relationship with time?