I intentionally delayed this reply (by > 5 days) to test the hypothesis that slowing down the pace of a conversation on LW will improve it.
Do you take the Fermi paradox seriously, or is the probability of your being destroyed by a galactic civilization, assuming that one exists, low enough?
When we try to estimate the number of technological civilizations that evolved on main-sequence stars in our past light cone, we must not use the presence of at least one tech civ (namely, us) as evidence of the presence of another one (namely, ET) because if that first tech civ had not evolved, we would have no way to observe that outcome (because we would not exist). In other words, we should pretend we know nothing of our own existence or the existence of clades in our ancestral line, in particular, the existence of the eukaryotes and the metazoa, when trying to estimate the number of tech civs in our past light cone.
I am not an expert on ETIs, but the following seems (barely) worth mentioning: the fact that prokaryotic life arose so quickly after the formation of the Earth's crust is IMHO significant evidence that there is simple (unicellular or similar) life in other star systems.
The evidential gap w.r.t. ET civilization spans billions of years -- but this is not evidence at all according to the above.
It is evidence, but less strong than it would be if we fail to account for observational selection effects. Details follow.
The fact that there are no obvious signs of an ET tech civ, e.g., alien space ships in the solar system, is commonly believed to the be strongest sign that there were no ET tech civs in our past light cone with the means and desire (specifically, desire on at least part of the civ that was not thwarted by the rest of the civ) to expand outwards into space. Well, it seems to me that there is a good chance that we would not have survived an encounter with the leading wave of such an expansion, and therefore the lack of evidence of such an expansion should not cause us to update our probability of the existence of such an expansion as much as it should have if we certainly could have survived the encounter. Still, the fact that there are no obvious signs (such as alien space ships in the solar system) of ET is the strongest piece of evidence against the hypothesis of the existence of ET tech civs in our past light cone (because for example radio waves can be detected by us over a distance of only thousands of light years whereas we should be able to detect colonization waves that originated billions of light years away because once a civilization acquires the means and desire to expand, what would stop it?).
In summary, observational selection effects blunt the force of the Fermi paradox in two ways:
Selection effects drastically reduce the (likelihood) ratio by which the fact of the existence of our civilization increases our probability of the existence of another civilization.
The lack of obvious signs (such as alien space ships) of ET in our immediate vicinity is commonly taken as evidence that drastically lowers the probability of ET. Observational selection effects mean that P(ET) is not lowered as much as we would otherwise think.
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So, yeah, to me, there is no Fermi paradox requiring explanation, nor do I expect any observations made during my lifetime to create a Fermi paradox.
When we try to estimate the number of technological civilizations that evolved on main-sequence stars in our past light cone, we must not use the presence of at least one tech civ (namely, us) as evidence of the presence of another one (namely, ET) because if that first tech civ had not evolved, we would have no way to observe that outcome (because we would not exist).
If there were two universes, one very likely to evolve life and one very unlikely, and all we knew was that we existed in one, then we are much more likely to exist in the first universe. Hence our own existence is evidence about the likelihood of life evolving, and there still is a Fermi paradox.
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