What Earth looks like to aliens | Sara Seager

Humans struggle to imagine life beyond Earth, often looking for anomalies or unusual signals in data. The "gold standard" for detecting intelligent life, as depicted in the movie "Contact," would be a distinct, ordered message received via radio telescope. However, this relies on a civilization actively beaming a signal towards us and the difficulty of constantly searching the entire sky. A technosignature, a sign of intelligent life with technological capability, offers alternative detection methods. These could include atmospheric changes, satellite swarms, city lights, large structures, or purposeful radio messages. With the acceleration of AI, we are beginning to create our own technosignatures, such as constellations of satellites in low-Earth orbit. This suggests that we could search for similar large, shiny objects, like patchy spheres of satellites, around other stars. Researchers have already examined existing infrared surveys for excess heat indicative of a Dyson sphere, setting limits on their presence. While many ideas are being implemented, nothing has been found yet, representing only a surface-level exploration. Another concept suggests that life might evolve into post-biological intelligence, a frontier research question concerning what AI will leave behind on Earth and what that implies for potential AI intelligence elsewhere in the universe. We are still trying to understand these implications.