SETI: the argument for artefact searches

For six decades, SETI has attempted to prove the existence of technologically advanced intelligence by detecting artificially generated electromagnetic signals. While such signals could certainly exist and – given the right circumstances – might be measurable here on Earth, contemporary searches are all compromised by limited sensitivity and a reliance on persistent transmissions. The energy required for any putative transmitters, the possible wish of the senders to be cryptic, and a likely ignorance about Homo sapiens’ existence all lead to the reasonable conclusion that greater attention to artefact searches could hasten the discovery of alien intelligence. We consider both the motivation, the advantages and the disadvantages of this approach. We also enumerate some of the specific artefact strategies that have been proposed and pursued.