[admiralfluff]

I think disease is an extremely unlikely cause for extinction. I would guess there have been no recorded infectious agents with a 100% kill rate (assuming a reasonable sample size). I think disease is a pretty good candidate for the end of civilization, but we're too genetically diverse for it to have much likelihood of causing our extinction.

ActionJeff- Rather than me finding and reading a book, I would much rather you just tell me what theory has supplanted accelerating expansion as a viable universal endgame.