‘Segan’ was wrong, in a very typical way for mainstream ‘skeptics’ who hew to dichotomization and status quo bias; absence of evidence is indeed evidence of absence. We have enormous opportunities to detect alien signatures, we have used them for many decades at enormous scale (and Sagan was involved in it), and we have come up with absolutely nothing whatsoever. Every time we have pulled a ball out of the urn of observations, it has come up labeled ‘not aliens’, and the odds that there’s any ball left in the urn labeled ‘alien’ goes down. Not a single Dyson sphere, not a single mega-structure, not a single anomalous artifact in the solar system, no traces of alien biospheres with different amino acid codings or chirality, and so on and so forth. Every time someone gets excited about a weird star or a weird comet/asteroid and says “this time it’s aliens!” and it could have been aliens, and yet, it turns out to not be aliens—the ‘alien hypothesis’ fails another test and shrinks in posterior probability a little bit more.
‘Segan’ was wrong, in a very typical way for mainstream ‘skeptics’ who hew to dichotomization and status quo bias; absence of evidence is indeed evidence of absence. We have enormous opportunities to detect alien signatures, we have used them for many decades at enormous scale (and Sagan was involved in it), and we have come up with absolutely nothing whatsoever. Every time we have pulled a ball out of the urn of observations, it has come up labeled ‘not aliens’, and the odds that there’s any ball left in the urn labeled ‘alien’ goes down. Not a single Dyson sphere, not a single mega-structure, not a single anomalous artifact in the solar system, no traces of alien biospheres with different amino acid codings or chirality, and so on and so forth. Every time someone gets excited about a weird star or a weird comet/asteroid and says “this time it’s aliens!” and it could have been aliens, and yet, it turns out to not be aliens—the ‘alien hypothesis’ fails another test and shrinks in posterior probability a little bit more.