If you plug values in drakes equations ou can make anything comes out. But historically with any like real numbers you get many civilizations right up until you state how long each civilization lasts. This is why Great Filters are such an important topic of discussion.
Try a calculator [1] and puch in your pessimistic and see what chances you actually get. It is really hard to get 10^20 without just getting 0, and we know the chances are higher than 0.
Try a calculator [1] and puch in your pessimistic and see what chances you actually get. It is really hard to get 10^20 without just getting 0, and we know the chances are higher than 0.
1 - http://www.bbc.com/future/story/20120821-how-many-alien-worl...