Editing Openai/6946e998-79f0-8007-9a65-19828450838d (section)

==== Here we’re in almost totally unconstrained territory; I’ll choose deliberately small numbers, but not so small that our own existence becomes paradoxical. ====

===== This is what people sometimes call f_life. We know life on Earth appeared relatively early (≲ few hundred Myr after oceans formed), which some argue is weak evidence that abiogenesis on good planets is not astronomically rare.PubMed Central<ref>{{cite web|title=PubMed Central|url=https://pmc.ncbi.nlm.nih.gov/articles/PMC7474626/|publisher=PubMed Central|access-date=2025-12-21}}</ref> =====

Still, you asked for pessimistic, so:

: 

Now N = 10⁵ × 0.01 = 10³ life-bearing worlds.

===== Call this f_intel: going from microbes to something roughly human-level (or better) over multi-Gyr. =====

We have no data other than Earth, where:
* complex multicellularity took ~3 Gyr to appear,
* technological intelligence appeared only once (as far as we know).

So I’ll again pick a small number:

: 

Now N = 10³ × 0.01 = 10.