Astronomy Cast Full Raw Feed · Fraser Cain & Dr. Pamela L. Gay

Ep. 741: Technosignatures

·59 min·5 clips

NASA researchers brainstormed 39 ways alien tech could leak signals, from Dyson spheres to nuclear war gamma rays.

This episode of Astronomy Cast explores the concept of technosignatures, or detectable signs of advanced technology from extraterrestrial civilizations. Hosts Fraser Cain, publisher of Universe Today, and Dr. Pamela Gay, a senior scientist at the Planetary Science Institute, guide the discussion. They reference a NASA-led conference where top researchers like Jason Wright and Seth Shostak brainstormed 39 potential technosignatures. One major topic is the search for infrared excess from massive structures like Dyson spheres or ringworlds, with astronomers using catalogs and machine learning to identify candidates like the mysterious Boyajian's Star. The hosts discuss how industrial pollution, such as chlorofluorocarbons in an exoplanet's atmosphere, could be an unambiguous technosignature detectable by telescopes like JWST. They examine the idea of detecting artificial transits, like a triangular object or a series of evenly spaced satellites passing in front of a star, which would produce an unnatural light curve. The conversation covers the potential to detect leaked communication signals, like laser or radio pulses between planets in systems like TRAPPIST-1 during orbital alignments. They speculate that advanced civilizations might rearrange stars into non-natural galactic structures using theoretical "shkadov thrusters." The hosts mention calculations showing future telescopes like the Square Kilometer Array could detect Earth's air traffic control signals from 100 light-years away. A surprising claim is that a civilization's waste heat from energy use, even if entirely green, could eventually cook its own planet and become detectable. One memorable idea is that the clearest sign of a warp drive might be the gravitational wave shockwave from its catastrophic failure, potentially detectable by observatories like LIGO. The hosts note that some proposed technosignatures, like specific atmospheric chemicals or geometric transits, are considered less ambiguous evidence than debated biosignatures like phosphine. The tone is conversational and educational, blending speculative science with explanations of current research methods. The style is enthusiastic and idea-rich, with hosts sharing personal anecdotes about travel and technology to ground the cosmic concepts. This episode would appeal to space enthusiasts fascinated by SETI and the creative boundaries of astrobiology. Listeners interested in practical astronomy or who prefer strictly confirmed science might find the speculative nature less engaging.

As heard by us

A grounded look at the sky-signs a civilization might leave behind.

Astronomy Cast treats technosignatures as a practical puzzle: if radio or laser signals are too costly, what would a civilization leave behind that the sky could still pick up?

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Want alien-hunting ideas that stay tied to the math?

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