"Contact," "Star Trek," "Babylon 5," "Star Wars," "Alien" and the rest of the lot have one thing in common: they all deal with alien civilizations and their relationships to humans. Some of these futuristic fictions portray alien life as friendly, some as hostile. Most of the aliens are curiously "humanoid." Many of us dream of one day meeting up with a (friendly) alien race. Much could be learned and discovered about each other. What are we doing right now to make this happen?

Is there anybody out there?
The world's largest supercomputer is searching the sky for alien signals and home computer users are donating their machines' idle time. The internet has made it all possible.

About 500,000 computer users are donating their idle computer time to the search for aliens in what claims to be the largest distributed processing project ever. (note: by 2001, there were 3,000,000 participants). The Seti@home (search for extra-terrestrial intelligence) software runs as a screensaver on Windows and Macintosh clients and as a low priority task on Unix machines. Using the internet, Seti@home is able to reach computers that would otherwise have wasted idle time animating toasters or slide-showing supermodels.

The project analyses data from the world's biggest radio telescope at Arecibo in Puerto Rico, piggybacking the long-running Serendip IV Seti programme. Each night the telescope scans the sky for signals, dumping 35GB of data onto tape. Because Arecibo does not have a high bandwidth internet connection, this tape is sent by post to the University of California in Berkeley, where the data is divided into 0.25MB blocks and sent out over the internet. Every five days for about five minutes, the
client computer automatically exchanges data with the server when the user connects to the internet. All
machines receive the same size work unit, regardless of their specification, and machines are sent new work once their batch is processed. The program consumes 20MB of disk space.

Each work unit has been planned to represent about 24 hours of screensaver time on a 233MHz computer, but computers have been taking an average of 39 hr 26 min to complete a work unit. Windows 95 machines have averaged a time as slow as 64 hr 34 min. Pentium/Windows machines
represent the greatest portion of the client base. Although many are running the client software without graphics on other platforms, Wertheimer admits that the screensaver's appearance could be a key factor in the project's success. "Many probably like the graphics and wouldn't run it unless it looked cool," he concedes.

Participants come from 203 countries including many developing countries. The top five countries by number of participants are the US, the UK, Canada, Germany and Japan.

The project is set to run for two years, after which the sky above Arecibo will have been scanned three times. Wertheimer puts the chance of finding an intelligent signal at "1% per decade", but knows what message he would send in reply given a free choice. "Please send all your music, literature, science and information about the other civilisations you've been talking to," he says. "And also, please, send information on how to hook up to the galactic internet."