[froeb]

I took some time to skim the original paper and learned about cosmological coupling for the first time! My understanding is that black hole solutions in an expanding spacetime have way more freedom than the regular Kerr solution, because Birkhoff's theorem doesn't apply anymore. This means you can get time varying black hole solutions, one of which involves "cosmological coupling" where the mass of the black hole increases with the expansion of the universe.

I think this is just a possibility allowed by GR though, I think you would need a theory of quantum gravity to say whether such "cosmologically coupled" mass actually exists in a black hole.

I suppose this research group is claiming to have experimental evidence of it though? That is very interesting if true.

Also, I am not sure how you go from cosmological coupling to saying that black holes are the "source" of dark energy. I need to read further