why seti is probably going to fail and why that’s really not a bad thing

If you’re an alien astronomer trying to figure out if there’s intelligent life on a little bluish and greenish planet orbiting a a distant star, astrophysicist Ethan Siegel has a warning for you. However you want to detect radio signals or the light coming from cities built by its inhabitants, do it now because that world is about to go dark and quiet very, very soon as far as you’re concerned. We’re not wiping ourselves out, far from it. We’re just broadcasting into space less and less while relying on cables to handle all our high speed, high throughput data needs, and switching to LEDs on a massive scale, meaning that our cities will be leaking a lot less light. Paradoxically, as our technology is advancing, and we’re communicating with each other more than ever, we’re becoming a lot harder to notice as an intelligent civilization to curious aliens. And when we become a truly space faring species, we’ll be just as hard to notice as we’ll use relays to talk to each other with highly directional laser pulses.

We’ve been trying to do some form of SETI, both active and passive, since the mid 1800s and so far have turned up a signal we can’t explain, weird dimming patterns around one star that’s most likely not aliens for many reasons, and a survey that most likely discovered a chemical anomaly in one type of star than multiple alien civilizations trying to contact us with lasers. Considering that it still isn’t clear if we’d ever even understand that we found an alien signal as it would be very difficult, if at all possible, for us to translate, and vice versa, one could reasonably ask whether SETI is basically doomed to fail. As we’re seeing on our own planet, looking for rogue signals by intelligent life, or even into a telescope, is kind of a crapshoot based on our own past. We could estimate if a nearby world has signs of biological activity, but to tell whether it’s intelligent from interstellar distances would be so complicated, it probably requires us to send a probe there to answer this question.

There may very well be a civilization within 30 light years or so building vast megacities across multiple planets in its solar system, but we’d never see of hear them if their technology is more advanced than ours was half a century or so ago. But of course this is assuming that the planet evolved complex, multicellular life a long time ago, presented conditions in which intelligent creature could evolve in such a way as to end up using tools and develop a culture, then expand into something capable of industrialization so it could end up with fairly advanced technology and the means to manufacture it at scale, and for the entirety of that time were no natural disasters big enough to outright wipe them out, or reset their civilization clock back to zero. All of those are really, really big ifs that rely on the sheer number of stars to make the math work.

It does stand to reason that in the vastness of this universe, we’re hardly some unique phenomenon because why would we be exceptional? But nothing that we know of leads us to think that intelligent life is common enough for entire civilizations to overlap in the timelines and close enough to detect each other and establish contact. For all its promise, SETI is the astronomical equivalent of getting in your car, and driving through a completely unknown city, looking not just for a person, but a wealthy stranger who randomly gives away million dollar checks to those stropped at random intersections. It can hypothetically happen, and knowing nothing about that city, it’s interesting to try and see if these generous strangers exist, but the odds would be always, always stacked against you ever being a recipient of this kind of generosity.

That said, if you never try it, you’ll never know what could have been, and not trying is the greatest sin in science. Even if experiments fail, we do learn from that failure so we know what might work better in the future, and we’re doing exactly that now. We’re beginning to understand the scope of the challenge, developing new models for detecting life, and understand that the best kind of active SETI involves vast telescopes and probes, not listening for signals or detecting what may look like weird dimming or radio pulses. Maybe one day, we’ll get an unambiguous detection this way, but just scanning the sky, hoping for a hello from an extraterrestrial civilization Contact style, seems like it’s going to be soon relegated by minor league status in our hunt for aliens. But again, it’s only happening because we learned from trying it this way first…