100 Final Signals Could Reveal First Contact With Aliens

Imagine millions of people around the world donating their computer power to answer humanity's biggest question: Are we alone in the universe? That dream became reality, and now scientists are checking the final 100 signals that could change everything.

The SETI@home project ran from 1999 to 2020, enlisting everyday volunteers to help search for alien signals. People downloaded software that used their computers' idle time to analyze radio telescope data while they slept or worked.

The response blew everyone away. Organizers hoped for 50,000 users but got 200,000 in the first week alone. Within a year, 2 million people had joined what became one of the largest citizen science projects ever attempted.

All that computing power churned through data from Puerto Rico's Arecibo radio telescope, scanning billions of stars in our galaxy. The software spotted 12 billion candidate signals, brief bursts of energy at specific frequencies coming from particular points in the sky.

Scientists spent years developing ways to sort through this mountain of data. Powerful algorithms at Germany's Max Planck Institute whittled 12 billion signals down to 1 million, then 1,000. Researchers examined those 1,000 by hand, eventually identifying 100 that deserved a closer look.

Since July 2025, China's FAST telescope has been following up on these final candidates. FAST is now the world's largest single-dish radio telescope, especially crucial since Arecibo collapsed in 2020.

The Bright Side

Scientists expect most signals will turn out to be local radio interference rather than alien messages. But that's not the point anymore.

"If we don't find ET, what we can say is that we have established a new sensitivity level," said David Anderson, who co-founded SETI@home. The project pushed the boundaries of what's possible when millions of people work together toward a shared goal.

The team also learned valuable lessons for future alien searches. They're now thinking about reanalyzing all the original data using modern machine learning and faster computers.

"There's still the potential that ET is in that data and we missed it just by a hair," said astronomer Eric Korpela.

Whether or not these final 100 signals reveal our cosmic neighbors, millions of ordinary people proved that together, we can tackle questions once reserved for science fiction.