For 21 years, enthusiasts have used their home computers to search for extraterrestrial life. UC Berkeley scientists have narrowed down 100 signals they 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 home 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 analyzed these detections, narrowing them down to a million 'candidate' signals and then to 100 that warrant further investigation. They've been using China's FAST telescope to study these targets since July, hoping to detect the signals again. Despite the lack of ET signals, the project offers valuable lessons for future searches and highlights potential flaws in ongoing efforts. The scientists have established a new sensitivity level, and if a powerful signal were detected, it would have been found. The project's findings, presented in two papers published in The Astronomical Journal, emphasize the need for better signal identification and exclusion methods. The challenge lies in developing algorithms to distinguish genuine signals from noise and radio interference, a task made more complex by the vast number of potential signals. To address this, Anderson and Korpela inserted 3,000 fake signals into their data pipeline, allowing them to calculate sensitivity based on detectable signal power. They suggest that a powerful narrow-band beacon, around the 21-centimeter radio wavelength, would be easier to detect and could lead to further observations of lower-power, wider-band signals containing information. Despite the absence of ET signals, SETI@home has been a remarkable success. It has demonstrated the power of distributed computing, attracting a million volunteers and achieving its initial expectations. The project's impact extends beyond its primary goal, inspiring future SETI searches and contributing to the advancement of radio astronomy. The software developed for SETI@home has been instrumental in analyzing radio data, employing mathematical techniques to identify potential signals. The project's success has paved the way for similar crowdsourced SETI initiatives, such as the use of the FAST telescope for commensal surveys and the BOINC platform for volunteer computing. With faster computers and internet speeds, these projects can analyze larger data sets, making the search for extraterrestrial intelligence more accessible and efficient.
