Science

The Search for Aliens Is Shifting Its Criteria | Sara Seager

Big Think
Big Think•Apr 7, 2026

Why It Matters

Broadening the search to include technosignatures and AI‑like markers increases the odds of detecting alien intelligence and reshapes funding priorities for astrobiology research.

Key Takeaways

  • •Traditional SETI relies on detecting intentional radio beacons
  • •Researchers now scan for technosignatures like city lights and Dyson spheres
  • •Infrared surveys set limits on alien megastructures' excess heat
  • •AI proliferation prompts search for post‑biological, machine‑based intelligences
  • •Current technosignature efforts remain surface‑level, with no detections yet

Summary

Sara Seager argues that the hunt for extraterrestrial life is moving beyond classic radio‑beacon SETI toward a broader suite of technosignatures.

She outlines how scientists now scan for anomalous infrared excesses, artificial illumination, satellite swarms, and even megastructures such as Dyson spheres, noting that existing sky surveys have already placed stringent limits on such phenomena.

Seager cites the iconic ‘Contact’ scene with Jill Tarter as the traditional gold‑standard, then contrasts it with today’s focus on AI‑driven signatures—low‑Earth‑orbit satellite constellations and potential post‑biological intelligences that could leave distinct, non‑radio footprints.

The shift expands the parameter space for detection, urging interdisciplinary collaboration and new instrumentation, while reminding the community that the absence of evidence so far is merely a shallow scratch on a vast cosmic surface.

Original Description

This interview is an episode from ‪The Well, our publication about ideas that inspire a life well-lived, created with the John Templeton Foundation.
Subscribe to The Well on YouTube ► https://bit.ly/thewell-youtube
Watch Seager’s next interview ► Why volcanoes might fool us into thinking we’ve found other intelligent life https://youtu.be/fPCuQcHusjQ?si=iIhM5MjK_zhofFf8
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.
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About Sara Seager:
Professor Seager is Director for the MIT-led Venus Morning Star Missions to Venus and lead for Project Starshade. In the past she was Deputy Science Director for the MIT-led NASA mission TESS and PI for the on-orbit JPL/MIT CubeSat ASTERIA.
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