> Black holes seem to be much more abundant than previously thought. Not really. The event rate seen by LIGO is well within the accepted range of uncertainty

> Black holes seem to be much more abundant than previously thought. Not really. The event rate seen by LIGO is well within the accepted range of uncertainty prior to turning LIGO on. The uncertainty range only tightened modestly, because there's been so little data, and only went upward a bit. I'd guess it was a "surprise", given a reasonable choice of priors of the community, at something like the 1-sigma level. Which is about the chance of it raining on any given day in San Fransisco -- not that surprising. > Maybe it is too obvious, but I'm wondering: could dark matter be made up of all those undiscovered black holes? This has been considered long ago, and generally disfavored for a few reasons, most notably being the lack of observed microlensing. https://en.wikipedia.org/wiki/Massive_compact_halo_object https://en.wikipedia.org/wiki/Massive_compact_halo_object The new data from LIGO is weak, and should not much change your mind about the likelihood of black hole being the dominant dark matter. (That is, the only people who should believe in BH DM are those who already did, of which there are a few.) This is an optimistic take: http://resonaances.blogspot.ca/2016/06/black-hole-dark-matter.html http://resonaances.blogspot.ca/2016/06/black-hole-dark-matte...