[zimzam]

I think I missed something: how do galaxies getting further away (divergence) imply that intelligent species will converge anywhere? It isn’t like one galaxy getting out of range of another on the other side of the universe is going to affect things in a meaningful way…

A galaxy has enough resources to be self-reliant, there’s no need for a species to escape one that is getting too far away from another one.

[wat10000]

You'll run out of resources eventually. Moving to the place with the most mass gives you the most time before you run out.

[exfalso]

Yes that's the idea. The expansion simply means that the window of migration will close. Once it's closed, your galaxy is cut off and will run out of fuel sooner than the high-density area.

[paulddraper]

Well eventually there are no galaxies just a bunch of cosmic rays. Some clusters of matter will last longer.

I think for this to work, either life would have to plentiful near the end, or you’d need FTL travel.

[jobigoud]

Social aspect. There is no need but it's more fun to spend the end of the Universe with other intelligences than each in its own place.