An alien hunt has been underway for more than five years using five million Internet-linked PCs, as part of a project called SETI@Home. With more than 70 teraflops of computer power, the SETI@ Home project is one of the world’s largest examples of grid computing.

The project, run by the University of California Berkeley, harnesses unused CPU cycles to comb through deep-space radio noise, searching for signals from extraterrestrials.

So after expending two million years of accumulated CPU time and analyzing 50T bytes of data, are we alone?

“We still don’t know the answer to the big question,” says Dan Wertheimer, chief scientist for the SETI@Home project. “We haven’t bugged any aliens yet.”

In true pioneer style, he added, “I’m optimistic that earthlings will find ETs in the long run. But don’t hold your breath.”