Re: Riddle me this:
"Or think of objects glued to a balloon. Inflate the balloon, and the objects move further apart."
I tried this once. What happened was, as the balloon expanded, the contact patch between the glue and the object also expanded, until, eventually, there wasn't enough adhesive in contact with the object to hold it in place, at which point it fell off. The object in question was a steak knife. I now have a 15mm hole in my foot.
Therefore I deduce that if the universe keeps expanding, we will all fall off and land in either heaven or hell, depending on which side of the universe we are on.
I saw the answer to this in a paper the other day and I realised my understanding of it wasn't as secure as I thought. Unfortunately I can't quite remember what the paper said or which paper it was. But it boils down to the "force" of metric expansion being much smaller than the forces holding you together - or even the "force" holding objects in orbit. So the expansion pressure on say, an orbital electron, is dwarfed by the attractive force of the nucleus and it doesn't even enter the calculations. Space "pushes" the electron out; the "Coloumb force" "pulls" it back.