Their estimate is based on several things, like the rate that stars form in our galaxy, the fraction of those stars that have planets, the number of those planets that can support life, the fraction of those that could develop intelligent life and build civilization, the fraction of those that could develop technology to release signals into space.
The average rate of star formation times the fraction of stars formed with planets that could support life, the fraction of those that could develop life and then intelligent life, the fraction of those that could develop technologies that might release detectable signals into space.
That’s not an equation.
It suggests there are over 36 million advanced civilizations out there. Doing all kinds of things that we just don’t understand.
-If that were true, we would’ve detected signals by now.
-Not necessarily. Space is a big, empty place.
Maybe all those other civilizations are gone. Maybe it’s the nature of intelligent life to destroy itself.
I think intelligent life could choose not to.
