For 21 years, enthusiasts have used their home computers to search for extraterrestrial intelligence (ET). UC Berkeley scientists are narrowing down 100 signals they've found. This ambitious project, SETI@home, has captivated millions worldwide, inviting them to contribute to the search for advanced civilizations in our galaxy. By downloading software to their computers, participants allowed it to analyze data from the Arecibo Observatory, seeking unusual radio signals from space. The computations yielded 12 billion detections, each a 'momentary blip of energy at a particular frequency coming from a particular point in the sky.' After a decade of work, the SETI@home team has narrowed these detections down to 100 signals that warrant further investigation. They've been using China's Five-hundred-meter Aperture Spherical Telescope (FAST) to study these targets, hoping to detect the signals again. Despite the lack of ET signals, the project's findings offer valuable insights for future searches and highlight potential flaws in current methods. The scientists have established a new sensitivity level, and if a powerful signal were detected, it would have been found. The project's challenges include distinguishing between real signals and noise, a task made more difficult by the vast number of potential signals. To address this, the team inserted fake signals into their data, allowing them to measure their sensitivity accurately. The astronomers suggest that a powerful narrow-band signal would be easy to detect and would likely be found near frequencies used by astronomers to map hydrogen gas in the galaxy. If an extraterrestrial narrow-band signal were detected, telescopes would be directed to that point, searching for other signals. The SETI@home project's success lies in its ability to engage a global community of volunteers, surpassing initial expectations. The project's origins can be traced back to Anderson's research in distributed computing, where large problems are broken down into smaller tasks for smaller computers. This approach was adapted for SETI@home, allowing for the analysis of radio telescope signals in search of technosignatures. The project's data came from the Arecibo radio telescope, which recorded signals passively as other astronomers studied different regions of the sky. This method proved effective, covering most stars in the Milky Way. Despite the lack of ET signals, the project's sensitivity and data coverage are remarkable. Current SETI searches often target specific stars or those with known planets, using radio telescopes like the Greenbank Telescope and the MeerKAT array. These telescopes can only detect relatively nearby signals, and larger telescopes are needed for deeper exploration. The SETI@home software utilized a discrete Fourier transform to analyze radio data, breaking frequencies into bins and searching for Doppler drift. The project's success in engaging volunteers and processing vast amounts of data has paved the way for future crowdsourced SETI projects. With the FAST telescope conducting a commensal survey, data can be distributed to citizen scientists for analysis using platforms like BOINC. Faster computers and internet speeds could enable the analysis of even larger data sets, making such projects more feasible and efficient.
