To be sure, terms denoting some form of alien "civilization" make speculating about the nature of ETs easier -- usually by implying that even the most technically savvy aliens, despite cultural differences, will be fundamentally comprehensible to present-day humans. But it's a big universe. If we achieve contact -- whether through the discovery of artifacts in our solar system or by happening across a telltale signal -- there's no promise the senders will hail from any sort of familiar social structure. Indeed, it's not unlikely that an alien intelligence "merely" a few thousand years ahead of us would completely defy comparison to terrestrial institutions.
I've always been frustrated by the prevailing assumption that aliens will eschew interstellar travel in favor of radio transmission due to the presumed cost of space travel. While aliens might suffer from constraints posed by limited access to resources, the notion of "cost" is rooted in our own brief, limited experience as social primates. We humans might bemoan the seemingly prohibitive price of manned spaceflight, but a more far-sighted intelligence might possess vastly different priorities. Spared the hurdle of terrestrial economic imperatives, I would expect aliens to prove surprisingly resourceful.
Contemporary discussion about a "post-scarcity" economy predicated on molecular manufacturing begs theorists to re-evaluate the likelihood that ET intelligences will conform to the models conceived by Frank Drake and Carl Sagan. For instance, instead of communicating with groups of like-minded beings, we may find ourselves in the midst of solitary god-like beings with only tenuous ties to their biological forebears. Allegiance to a community might turn out to be a uniquely human trait.
If galactic civilizations are indeed exceptional rather than the norm, much of SETI's operative wisdom will demand reinvention. For example, we may have to dispense with realistic hopes of happening across Sagan's "Encyclopedia Galactica." Likewise, we may never be invited to "join the club" -- not because we're not deserving, but simply because there's no club to join in the first place.
Ultimately, I'm haunted by a vision of a Cosmos inhabited by forever-roaming AIs who have long since jettisoned the quirks and baggage forged during their ancestors' brief tenure as biological beings. Some of these wandering minds might be quite indifferent to the antics of emerging technological civilizations such as our own. Others, possessed of infinite patience, might choose to observe.
But the ones who want to play are the ones that interest me most of all.
This piece originally appeared at aboutSETI.com.