Is anybody out there? Probably. Most stars have planets; we've discovered more than 6,000 exoplanets thus far, and the most basic statistics point toward the existence of countless potentially habitable worlds in the universe. But when we have looked for any scrap of evidence for alien civilizations, we have found nothing so far. The question is why?

There are the usual ideas: life actually doesn't find a way; Earth is being kept in a cosmic zoo; civilizations destroy themselves as soon as they have the power to do so; some civilization has to be the first, and that's us. None of them are really provable at this point, and none of them are particularly satisfactory answers. So why not add another idea to the mix? What if the reason we haven't detected aliens is because of AI?

This idea comes from a new paper posted to the arXiv preprint server that re-examines some musings of Carl Sagan. Back in the 1970s, Sagan considered some of the challenges of the search for extraterrestrial intelligence, and one of them was what he called the "communication horizon."

The idea was that as an alien civilization advances, its technology becomes too sophisticated for us to detect. We could detect strong radio signals from a civilization 100 light-years away, but if they use neutrino communication, they'd be essentially invisible to us. And if there is some novel physics that allows them to communicate faster than light? Our search is doomed.

Sagan figured that it would take about a thousand years for a civilization to progress outside our observational limits, based on the way human civilization had advanced in the past. But a great deal has changed since Sagan's day, particularly in the area of computer technology.

These days, artificial intelligence is all the rage. Like it or hate it, AI is now a part of our daily lives. It's quite possible that the advancement of AI will reach some technological plateau, but it's also possible that we will achieve some kind of artificial super-intelligence (ASI). If an ASI appears in the next decade or so, it would become the dominant intelligence on Earth, and it would continue to advance at a rate faster than we poor lumps of flesh can imagine.

This latest work argues that if we factor in the exponential rate of technology and consider the possibility that non-biological intelligence is common, then the observation horizon shrinks considerably. It could be as short as a decade or two. If that's the case, then our chance of detecting an alien species is essentially nil. Perhaps the answer to Fermi's paradox of the Great Silence is the Dead Internet Theory on a cosmic scale.