An intriguing overview of the ways in which science could find evidence for extraterrestrial  life   Are we alone in the universe, or is life a universal phenomenon?  For fifty years, astronomers in SETI (Search for Extraterrestrial Intelligence) have scanned the universe for intelligent signals, but with no success. In this intriguing book, Edward Ashpole explains the probable reasons for this and discusses other avenues of investigation more in line with the nature of science and technology. The author examines the problems inherent in scanning the universe for radio or optical signals from an alien intelligence. These include the difficulty of trying to communicate with another species possessing a completely unknown form of technology and the vast distances that alien communications would have to travel to reach us.