[TheOtherHobbes]

Or it's so easy.

Ants live in cities surrounded by humans, but have no idea what a human is or what humans do, and literally cannot experience - never mind imagine - what a human is, what a city is, what transport networks are, what culture is, what technology is.

Every so often an ant nest is destroyed because it's an irritant, but if the ants notice at all they carry on relatively unthinkingly. There are only other ants, pheromone trails, and food sources. [Other] may register very fleetingly but does not align with any ant concepts or ant goals, and therefore leaves no lasting impression.

Wide differences in intelligence make more advanced lifeforms invisible - not physically but conceptually. Which turns out to amount to the same thing in practice. Even between two species who share the same physical space.

We could be surrounded by a universal or galactic civilisation and we wouldn't know.

[lariati]

Or a combination of both. Ants are a great example though. Like 10 million ants per person on Earth and they are almost all invisible to humans.

I would think there is quite a bit of intelligent life in the universe that all feels equally alone.

Space constraints * time constraints make this a near insurmountable problem and then even if that is overcome then it gets multiplied again by the minuscule probability with sharing anything close to perception like the ants.

Not to mention we are going to be orders of magnitude closer to ants in perception than to aliens from a different planet.

[pharke]

I think the Arthur C Clarke quote "Any sufficiently advanced technology is indistinguishable from magic" should perhaps be amended to "Any sufficiently advanced technology is indistinguishable from nature" it doesn't quite have the same ring to it but it's probably more truthful, at least for very, very, very advanced technology.

[ncmncm]

Rocky planets are for only the most extreme primitives. If anybody noticed us at all, they wouldn't have any interest in talking. They might probe us. Maybe copy somebody into a simulator that works a million times faster, and quiz that, instead?

All the action is out in the Kuiper belts, where there is abundant cold, which is more valuable than any material substance.