Idea for a science fiction short story: dark matter interacts with normal matter only in specific conditions requiring advanced science, with extremely rare occurrences naturally.
Humanity, after migrating from biological carbon based substrate, finds ordinary matter not practical to live in. Dark matter has much better properties.
All humanity transfers to dark matter where it finds all the other "ascended" species historically hosted by our universe. Solves Fermi's paradox and keeps the "normal matter" nursery clean for new species to appear.
Curious indeed. But that "Humanity" part is a bit stale. I'd make it the not too far end after the current or next speciation event ... then "time travel" can get it's more or less natural and scientific manifestation when that ascended gene pool somehow suddenly notices that genomes from their archives are born to non-descendant parents .. [ spontaneous genetic recurrence, probabilistic replication, or a wild-type convergence? *had to use AI to pin down these terms, I'm tired ]
This is a cool idea.
I was tempted to comment that there’s no evidence that you can make anything complex out of dark matter, but it turns out that some physicists hypothesize that “self-interacting” dark matter could bind into something like atoms and molecules, so carry on!
It's worth noting in passing that “some physicists hypothesize” is entirely compatible with “there’s no evidence”; this should not be disqualifying for science fiction.