User blog comment:Primussupremus/Where would the Busy Beaver function come in the fast growing hiearchy./@comment-1605058-20170416100356/@comment-1605058-20170416115728

As for absolute infinity: I would describe it as an idea of having the entirety of transfinite ordinals and considering it as a single object.

As for FOOT: Unless you ask a more specific question I can't explain it any better than I have in my blog post.