Editing Talk:2643: Cosmologist Gift

:If dark matter was 100% particles, then a volume on Earth containing 30,000 solar neutrinos would have 12 zeptograms of dark matter, not 4. Since the box is labeled with only a third as much dark matter, the implication is that Randall might think some is clustered in MACHOs. (I'm going to ignore modified gravity, which gets more attention than non-PBH MACHOs but way less than PBHs, and has some foundational issues along with zero successful simulations compared to very successful large-scale simulations using generalized DM.) In the past decade the only MACHO DM theory with more than a handful of papers per year is PBHs, which skyrocketed in popularity after LIGO/Virgo, but are still less popular among mainstream cosmologists than 100% WIMPs. The elephant in the room is that there's lots of evidence for intermediate mass black holes (LIGO/Virgo being the most compelling, but recent indirect observations exist too) but only one out of about thirty WIMP detector experiments have painfully meager positive results, which nobody else has been able to replicate. It's been a similar situation for almost four decades now. Back in the mid-1970s dark matter was assumed to be mostly 100,000 solar mass black holes. A couple generations of constraints assuming monochromatic mass suggested it was a particle instead. But all the constraints, including microlensing, which assume all black holes have even approximately similar masses had to be rejected after the LIGO/Virgo results.