Naked Astronomy, from the Naked Scientists · The Naked Scientists

SETI: Looking for Life across the Universe

·31 min·3 clips

The Square Kilometre Array could detect our TV signals from Alpha Centauri for the first time.

This episode explores the scientific search for extraterrestrial intelligence, hosted by Ben McAllister and Adam Murphy of the Naked Scientists. They are joined by Andrew Siemion, director of the Berkeley SETI Research Centre, to discuss the field's methods and history. The conversation traces humanity's long-standing curiosity about alien life, from ancient cultures to 19th-century scientific ideas like using geometric shapes as interstellar signals. Nikola Tesla believed his inventions could detect alien radio signals, while Giovanni Schiaparelli's observations of Martian canals fueled public interest. The hosts note historical UFO accounts, like the 16th-century Nuremberg event documented with peculiar newsprint illustrations. Modern SETI began around 1959 with a seminal paper by Giuseppe Cocconi and Philip Morrison and the first search by Frank Drake, who also formulated the famous Drake Equation. SETI now encompasses multiple global research groups beyond the well-known SETI Institute. Current searches primarily look for electromagnetic signals from technology, such as deliberate communications or "leakage" radiation from civilizations. Projects like Breakthrough Listen use telescopes like the Automated Planet Finder and the TESS satellite across the radio and optical spectra. A key future tool is the Square Kilometre Array, which will be sensitive enough to detect leakage radiation from a civilization like ours around the nearest stars. Distinguishing artificial signals from natural phenomena relies on identifying high "coherence," a compressed structure in frequency or time not typical of cosmic sources. Historical signals like the "Wow!" signal from 1977 are now generally considered potential radio interference from Earth. Pulsars, initially labeled LGM for "Little Green Men," exemplify rare natural phenomena with high coherence. The discovery of ubiquitous exoplanets, with many in habitable zones, provides optimism about the prevalence of life. The episode also touches on active messaging, referencing the diverse contents of the Voyager Golden Record as a model for representing humanity. Andrew Siemion highlights reduced spacecraft launch costs enabling future telescopes on the Moon's far side, away from Earth's interference. He notes a significant surge in student and scholar engagement in SETI compared to a decade ago. The tone is conversational and educational, blending historical anecdotes with explanations of current research and future technologies. Listeners interested in astronomy history, the science of exoplanets, or the technical methods of cosmic discovery will enjoy this episode. Those seeking definitive proof of aliens or discussions of UFO conspiracy theories might find it too grounded in established scientific practice.

As heard by us

A grounded, approachable introduction to SETI and signs of technology beyond Earth.

SETI is treated here as a real observing problem, not a thought experiment. The hosts walk through how a civilization might give itself away, moving from radio to optical links to large orbital structures like a Dyson structure, and the guest adds useful depth without weighing…

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You want a lively primer on how scientists look for extraterrestrial life and the tech clues it might leave behind.

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