For fifty years, astronomers involved in SETI (the Search for Extraterrestrial Intelligence) have scanned the universe for intelligent signals, but with no success. Ashpole examines the problems inherent in scanning the universe for radio or optical signals from an alien intelligence (the difficulty of trying to communicate with another species possessing completely unknown forms of technology and the vast distances that alien communications would have to travel to reach us) and considers other ways of finding evidence for extraterrestrial life, given that advanced civilizations would probably use artificial intelligence for interstellar travel. Scientists now know how to detect the presence of life on a planet by observing its spectral lines, so more advanced alien researchers would have had ample time (about two billion years) to investigate these “signatures of life” coming from Earth. Hence alien space probes could exist within our own solar system; there might be evidence on the erosion-free Moon or on another moon or planet.
|(SETI * OUTER SPACE * EXTRATERRESTRIAL LIFE SEARCHED)