Usually SETI looks for narrow radio signals, but Earthly tech generates broadband noise. Perhaps advanced civilizations also 'hum' on a planetary scale. The authors suggest hunting for such technogenic background with a telescope cascade: new array surveys and pinpoint checks. A broadband signal doesn't drift, allowing long observations and detection up to 100 parsecs — like eavesdropping on alien internet.
For decades, the search for extraterrestrial intelligence was waiting for quiet whistles from space. But our own technosphere has created a continuous radio background—like the hum of a vast metropolis. If nearby stars have sensitive antennas, they already hear this noise. SETI is now learning to pick up similar "noisy cities" on other planets.
The method has two stages: a quick sky survey for bright radio spots, then a detailed examination with a network of antennas. A technogenic source is identified by its anomalous radio brightness (it "shines" in radio like an overheated object, but without real heat), lack of circular polarization, and scintillation in cosmic irregularities. The final test is synchronous motion with the star. These observations will complement the exoplanet data from the Kepler mission William Borucki.
🎯 If a narrow radio beacon is a lone whistle in the night, then a planet's technogenic hum resembles the cacophony of a big city: a mix of conversations, engines, and music across all frequencies.
🎬 In Carl Sagan's novel "Contact," aliens sent a complex narrow signal. The new approach suggests we're more likely to pick up the unintended noise of their technology—the same kind our own internet traffic generates.