One—and some serious planetary scientists and astronomers back this theory—is that we really could be alone: that life itself is rare and intelligent life probably confined to one planet. Not so, say others: the raw materials for life as we know it are being manufactured by exploding stars and carried by icy comets all over the solar system and—since the Copernican principle says there is nothing special about the Earth—by extension, everywhere. Which brings us back to Fermi. Where is everyone? Life must be common, even if communities are light years apart.
Life may indeed be common elsewhere, but I’d reckon sentience—and by extension, technology—would be an extremely rare occurrence. Exceedingly, exceptionally rare. You don’t find remnants of troodontid architecture or deinonychus nuclear installations, and their ilk had hundreds of millions of years to play around. It’s possible something might turn up, but that’s groundless speculation on my part (dino discotheque remains, not prime numbers from space). Humans got lucky. Or maybe it’s just the monolith. In any case, despite the seeming odds, it doesn’t hurt to listen to the great beyond.