Extraterrestrials in existential trouble might be easiest to find—and also the most informative
Apocalypse is a word that we throw around pretty readily these days, and we can choose from a cornucopia of terrifying options—from the fierce ochre skies of western North America to the seemingly endless days of a global pandemic, to the suffering of mass migrants and the trauma from unstable political leaders (the specifics of which I leave to your imagination). But it’s a bit unfair to this overused term. The more literal, root meaning of apocalypse, from its construction out of ancient Greek, is “an uncovering.” It is a revelation of knowledge, of what lies beneath the usually perceived reality.
What lies beneath day-to-day reality is a fantastically complex web of phenomena. A web of our individual biological machinery and its place within a four-billion-year story of propagating genetic information and molecular processes, and of the exponentially complicated interplay between competing, cooperating, and merely indifferent systems. Whether in the form of organisms and their biophysical games with inanimate environments, or the back and forth of feedbacks in the dynamics of a well-heated, chemically rich rocky planet.
Perturb that web, poke it or shove it, and there are ripples that don’t always settle quickly. Planetary climate is one major structural element of the web, and is perfectly happy to ripple and slide over to states that modern humans haven’t experienced before. In that sense the revelation of “apocalypse” is indeed appropriate for much of what we’re seeing happening to our planet at the moment; an uncovering of the true cycles and mechanics of the physical and biological world.
But there may be even deeper revelations at play that don’t apply just to the Earth at this particular moment. There are two principal aspects to these. The first is that if there are life-harboring planets elsewhere in the universe, the ones experiencing dramatic and rapid shifts in their conditions might also be the ones that are easiest to identify as living worlds as we peer through our telescopes (a topic I’ve written about in the past). The second aspect is that it’s possible that sentient, technological species experiencing change and trauma might be the ones most likely to give away their presence to the rest of the galaxy.
For example, the trigger for that trauma might be when species approaches a particular level of planetary dominance. With their civilization reaching a tipping point of scale that is far more likely to produce detectable technosignatures for distant astronomers—whether as infrared excesses from waste energy or a flood of peculiar atmospheric compounds from polluting industrial processes.
But it could also be that it is precisely at this point in its existence that a species begins to really look beyond its planetary confines. Is it a coincidence that human spaceflight and dreams of putting settlers on Mars are revving up today in a way that they haven’t for decades? Or a coincidence that there is a resurgence of scientific interest in the search for extraterrestrial intelligence? Or that there is an ongoing acceleration in machine learning and algorithms and devices that have the potential to grow exponentially and subvert aspects of our cognitive existence?
I think it’s an interesting idea to consider that civilizations (for want of a more general term) may only begin to make their presence known in the universe when things get really busy, and really bad, at home.
Apart from passive technosignatures, like rapid climate change, the launch of interplanetary or interstellar spacecraft could, if beamed-light propulsion is utilized, produce potent signals detectable elsewhere in the cosmos. Communications with a growing population of exploration vehicles and settlements within a planetary system, or with probes launched to other stars, could also create a noisy beacon for other species to detect. Even efforts to terraform other worlds (and of course this is stretching the realm of possibilities a little), would present a rather shocking event to advanced alien observers steadily tracking the properties of a system.
And perhaps the ultimate in last-ditch attempts to avert a slow-rolling planetary disaster is to send out a distress signal, looking for answers to existential challenges; because at that point why not?
There is a catch though, and it relates to the well-worn ideas of the Fermi paradox. By the time a species is compelled into doing any of these things, and even before its planetary environment is pushed to a Klaxon-like tipping point, perhaps it simply fails. There is no Hail Mary, there isn’t even a noticeable last gasp, instead it all just shuts down. In which case the apparent absence of any evidence for other intelligence in the universe is not just because of our limited searches to date, it is because of a great filter that—like an exhausted parent—just puts an end to any coherent change. There is no bang, and there isn’t even a whimper.
That is of course awfully depressing. But there is a ray of hope, and it’s in the fact that our quest to look for other technological life in the universe is very, very far from complete. We may yet find ourselves detecting the shrieks of civilizations across our galaxy. Even if they’re experiencing their own apocalypse, we would learn critical things about the properties of a great filter; that there might be time yet to slither past it, and that at least we still have a way to go.