Just over 40 years ago, in his novel Contact, astronomer Carl Sagan imagined what it would be like to detect radio signals beamed from other intelligent lifeforms in the galaxy. In the story, these extraterrestrial beings send blueprints to build a spaceship to carry a handful of Earth travelers to meet with them.
While the book lies firmly in the realm of science fiction, Sagan’s expertise gave it a rare level of technical realism, offering a plausible sequence of events in which astronomers identify a radio signal of alien origin.
Yet after a century of listening, we are still alone in the vast cosmos — though that has not killed the hope that radio telescopes could open a line of communication to alien civilizations. In fact, we have barely begun to search the galaxy, having scanned only a fraction of its star systems. But that could soon change thanks to next-generation telescopes and AI-assisted data analysis.
The coming decade will see the biggest jump in search capabilities since the field began, raking in unprecedented torrents of data — a welcome development for astronomers. If we want to understand why we haven’t found anything, “we need to do more of everything — expanded frequency ranges, broader sky coverage, more frequent and detailed observations,” said Steve Croft, an astronomer at the SETI (Search for Extraterrestrial Intelligence) Institute and the University of California, Berkeley. “We haven’t looked well enough yet to say much so far.”
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