This content is locked. Please login or become a member.
Astrophysicist Sara Seager has spent decades expanding how we search for life beyond Earth: not by asking what we would look like out there, but by imagining forms of intelligence that may be utterly unlike our own.
Her work explores “technosignatures” — physical clues of advanced life, from satellite swarms to artificial light. As artificial intelligence accelerates here on Earth, Seager considers whether post-biological life might be what awaits us — and whether it already exists elsewhere in the cosmos. Our biggest challenge, she suggests, may be learning to see past the limits of our own imagination.
SARA SEAGER: As humans, it's so hard to think outside of the box, outside of who we are.
We are looking for life beyond Earth in all kinds of ways. It's so hard to imagine things that aren't already part of our life. It's really, really hard to extrapolate. So one idea is people like to look for anomalies. Like, you look in data for spurious signals, signals that aren't something that we normally see.
In the movie “Contact,” the character that plays Jill Tarter eventually gets a message on the radio telescope that's a distinctive message from another intelligent civilization.
That is like our gold standard, because we're not going to just get a random signal from the universe that's ordered in a certain way. But we have to get lucky that someone's actually beaming a signal right to us. And it's just hard to search the whole sky constantly.
A technosignature is a sign of intelligent life that has technological capability. We have a lot of those in our atmosphere that could potentially be detected from far away.
A techno signature could also be swarms of satellites. There could be city lights or large structures that have been built. And one more very popular one is a radio message, a radio signal, like a purposeful message.
Living right now, with AI accelerating in its so-called “intelligence” is terrifying in a way, really. And so it's really fresh on our minds. We're starting to have a signature of AI, computer intelligence, because we have constellations of satellites in low-Earth orbit for communications or for Earth observing.
So we could look for large, shiny objects, which would be a sphere, or like maybe not a continuous sphere, but like a patchy sphere of satellites around another star.
And people have literally searched through infrared surveys that already existed of our sky, looking for excess heat, like coming off of what would be a Dyson sphere, and put limits on it.
So there are like a giant list of ideas that are slowly being implemented, and so far they haven't turned anything up. But they’re still just a scratch at the surface.
But another concept in that great filter is that perhaps life evolves to this post-biological intelligence. This is like a frontiers research question about what AI will leave behind. What will it evolve to here on Earth, and what does it mean for potential AI computer type intelligence elsewhere? We're still trying to figure that out.