Radio Technosignature Research
A 97-galaxy radio search found no surviving signal
Worth Revisiting: Breakthrough Listen examined 100 terabytes of Green Bank data and set limits on enormously powerful extragalactic transmitters.
Briefed September 5, 2026 · Aliens in the Clouds
Worth Revisiting · Peer Reviewed · Null Result
Breakthrough Listen researchers searched 229 hours of Green Bank Telescope observations covering the centers of 97 nearby galaxies across four radio bands from 1 to 11 gigahertz. Their pipeline examined more than 100 terabytes of data for narrowband signals with Doppler drift, producing 1,319 initial candidates before checks for radio-frequency interference and on-source versus off-source behavior.
No candidate survived as a technosignature. Because a transmitter detectable across intergalactic distances would need an equivalent isotropic radiated power near 10 to the 26 watts unless aimed toward Earth, the null result constrains only extremely powerful beacons in the observed frequencies and times. It does not show that the galaxies are uninhabited, and a September 4 explainer revived interest in research first published in 2024.
Why it matters
Null results define what was actually searched and what remains open, replacing the vague statement that humanity has 'listened for aliens' with explicit sensitivity, bandwidth, targets, and thresholds.
What the source establishes
Peer-reviewed Astronomical Journal study with no surviving technosignature candidate. The search constrains specific high-power narrowband transmitters, not all technology or life in those galaxies.
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