The Origins of Dark Matter

Primordial black holes may not be the dark matter, but they're still an interesting thing to study. They could have played a role in explaining the matter anti-matter asymmetry of our universe. It's really just gravity doing the work, which means that it will produce all kinds of matter no matter how weakly interacting it is. So we can see that these masses up to about 10 to 17 grams as being all of the dark matter.