On May 17, 1999, the Space Sciences Laboratory at UC Berkeley released a screensaver that let ordinary computers sift radio telescope data for signs of extraterrestrial intelligence. The data came from the Arecibo telescope in Puerto Rico, which had no connection fast enough to send it, so recordings were mailed to California on hard drives and chopped into 350 kilobyte work units of about 107 seconds each. More than 5.2 million participants in 233 countries eventually logged over two million years of computing time.

This episode explains what the software was actually hunting for, from power spikes and Gaussian rises to pulsing signals corrected for Doppler drift, and what happened when leaderboards turned astrophysics into a sport. Volunteers built basement server farms, hacked the client for speed, and secretly installed it on employer networks, a practice known as Borging. No alien signal was ever confirmed, yet the project reshaped scientific computing through the BOINC platform.

• Roughly a third of early processing power came from work or school machines, and the state of Ohio fired an employee for running the software on state property.
• A school IT director resigned over an installation blamed for one million dollars in cleanup costs, a figure a ZDNet editor found suspicious.
• To beat cheaters, every work unit went to at least two unconnected computers, and both users received the lowest credit either one claimed.
• The best known candidate, radio source SHGb02+14a, was announced in September 2004 but did not survive verification.
• Berkeley put volunteer computing into hibernation on March 31, 2020, and the team now plans to recheck its top 100 candidates with 24 hours on China’s FAST telescope.