Nearly 5m people in 226 countries have downloaded a screensaver that makes their computer available, whenever it is sitting idle, to process radio signals gathered from outer space.

ECONOMIST: The future of computing

He said life in space was extremely busy, with no spare time to be idle.

BBC: Chris Hadfield: 'Space was too good not to share it'

Started in late 1998, the space-alien hunt has recruited the owners of 2.5 million PCs, tapping their machines' idle processing time to search small chunks of radio telescope data for patterns that might signal intelligent life elsewhere in the cosmos.

FORBES: Sharing Power