[avaldes]

> It would likely imply they found a way to relatively cheaply attain faster-than-light travel, for example, perhaps by some kind of spacetime-manipulating mechanism like wormholes or Alcubierre/warp drives. (Which some scientists believe could maybe be theoretically plausible one day, given enough scarce resources.)

Not necessarily though. It could be a generational ship with mundane propulsion technology.

[meowface]

It could be, but my blind guess is that if there are any intelligent lifeforms out there, they're so far away that conventional propulsion craft would have to fan out and run for so long that it's unlikely they'd happen to run into us at all, or if they do, not at a time when any of us exist. And if they were already doing that within a reasonable distance from us, I think we'd probably have already seen evidence of some of the swarms somewhere.

And it'd also probably have to be immortal autonomous machines rather than anything biological, which wouldn't necessarily be as useful, unless they fully merged with them or created ones that were much smarter than they are. (Which I suppose is pretty possible, given we might do the same within a century or two.)

My guess is we may unfortunately possibly be the only intelligent life throughout all of reality up until now (extremely speculative, I know), or that the few civilizations that do exist or have existed are so spaced apart from each other that it's very unlikely any will ever run into or observe any of the others without some kind of major FTL breakthrough.

[throwaway316943]

I think it makes much less sense for aliens arriving by conventional means to not contact us. If they did then they’re being extremely generous by not attempting to colonize Earth or any of the other planets. It’d be like European explorers discovering the New World is inhabited and deciding to stay off shore. It also wouldn’t explain the anomalous, physics defying video and accounts of UFOs. On the other hand, if interstellar travel is trivial then there is much more leeway for taking a hands off approach. In that case we’re just the North Sentinelese and they’re the yachts and airplanes staying out of bow and arrow range.