Such a set of probabilities may be justified if you’re very uncertain (as seems superficially reasonable) about the baseline probability of life arising in any given galaxy. So perhaps one might assign a ~40% chance that life is just incredibly likely, and most every galaxy has multiple instances of biogenesis, and a ~40% chance that life is just so astronomically (har har har) improbable that the Earth houses the only example in the universe,
This is almost certainly much less reasonable once you start thinking about the Great Filter, unless you think the Filter is civilizations just happily chilling on their home planet or thereabouts for eons, but then not everybody’s read or thought about the Filter.
The bigger problem to me seems that both the numbers (galaxy and universe) are way too high. It seems like it should be more in the range of “meta-uncertainty + epsilon” for both answers. Maybe “epsilon * lots” for the universe one but even that should be lower than the uncertainty component.
Such a set of probabilities may be justified if you’re very uncertain (as seems superficially reasonable) about the baseline probability of life arising in any given galaxy. So perhaps one might assign a ~40% chance that life is just incredibly likely, and most every galaxy has multiple instances of biogenesis, and a ~40% chance that life is just so astronomically (har har har) improbable that the Earth houses the only example in the universe,
This is almost certainly much less reasonable once you start thinking about the Great Filter, unless you think the Filter is civilizations just happily chilling on their home planet or thereabouts for eons, but then not everybody’s read or thought about the Filter.
I was kind of hoping most LWers at least had heard of the Great Silence/Fermi controversy, though.
Maybe there should be a question or two about the Fermi paradox.
The bigger problem to me seems that both the numbers (galaxy and universe) are way too high. It seems like it should be more in the range of “meta-uncertainty + epsilon” for both answers. Maybe “epsilon * lots” for the universe one but even that should be lower than the uncertainty component.