I personally believe FTL is likely impossible so I think the only realistic hypothesis is if we encounter aliens, that they're von Neumann drones on the vanguard edge of a colonization wave from an alien race that's been doing it for millions of years.
If we survive for long enough as a species, either we'll meet races in this manner or we'll be the ones doing it.
For the record I still only assign a fairly low probability that this is what is happening, it's more likely that UAPs are craft from terrestrial origin.
If we survive for long enough as a species, either we'll meet races in this manner or we'll be the ones doing it.
For the record I still only assign a fairly low probability that this is what is happening, it's more likely that UAPs are craft from terrestrial origin.