Other questions tackle why space doesn't expand matter, and I've read their respective top answers, but I'm interested in something a little different.
Let's say I set up two masses that are 1 Mpc apart and put a stretchy filament between them. If:
- the metric expansion of space is happening, and
- as other answers on this site suggest, matter itself is not expanding because that expansion is being counteracted by other stronger forces like electromagnetism, then
then is it correct that these objects are moving apart from each other without growing in size?
And if so, does that mean that the filament we placed between them is storing energy that can be exploited to do useful work?