Conclusion 1: the Fermi paradox isn’t very paradoxical
- Overconfident guesses makes it seem hard to get empty universe
- When our uncertainty is properly accounted for in the model, we find a substantial a priori chance that there is no other intelligent life in our observable universe, and thus that there should be little or no surprise when this is what we see.
- Reasonable priors (or even the literature!) give enough uncertainty to make empty universe fairly likely
- Note that this conclusion does not mean we are alone! Just that we should not be surprised if this is the case.
(This is a statement about knowledge and priors, not a measurement: armchair astrobiology)
Conclusion 2: the great filter is likely in the past
- Given the priors and the Fermi observation, the default guess should be that the low-probability term(s) are in the past.
- Note that a past great filter does not imply our safety
(The stars just don’t foretell our doom)