Originally posted by twhitehead
Here is one argument against black holes.
http://www.businessinsider.com/macho-black-holes-dark-matter-problem-2016-8

One potential problem I see with Macho's is this: if they formed in the first few seconds of the BB what would have prevented them from just being attracted to each other and just be one big black or a smaller number of bigger black holes which would have reduced the overall number to a number that would not be enough to be the distribution we see today.

Originally posted by sonhouse
One potential problem I see with Macho's is this: if they formed in the first few seconds of the BB what would have prevented them from just being attracted to each other and just be one big black or a smaller number of bigger black holes which would have reduced the overall number to a number that would not be enough to be the distribution we see today.

Why did that not happen to luminous matter?

Originally posted by sonhouse
One potential problem I see with Macho's is this: if they formed in the first few seconds of the BB what would have prevented them from just being attracted to each other and just be one big black or a smaller number of bigger black holes which would have reduced the overall number to a number that would not be enough to be the distribution we see today.

It depends on the size and when exactly they are supposed to have formed. During inflation the universe expanded very rapidly so gravity really wasn't a factor ie objects just didn't have time to merge. How inflation would affect black holes might be interesting.

Originally posted by twhitehead
It depends on the size and when exactly they are supposed to have formed. During inflation the universe expanded very rapidly so gravity really wasn't a factor ie objects just didn't have time to merge. How inflation would affect black holes might be interesting.

https://en.wikipedia.org/wiki/De_Sitter%E2%80%93Schwarzschild_metric