AMA | September 2024

13203.858 - 13227.512 Sean Carroll

It's easy to come up with an example of a neutral, stable, invisible particle. It's very hard to get the right abundance. There's a lot of constraints there. But most of the successful theories don't really pin down the abundance to any hyper-specific number. Like, there's usual free parameters in there where if they were a little bit different, you would get a very different abundance.