Searching for extraterrestrial intelligence across a century

Abstract SETI, the Search for Extraterrestrial Intelligence, is an old idea but a new science. Both inspirational and controversial, the scientific search for non-human artificial signals or communications, known as technosignatures, was pioneered by a few visionary scientists and through amazing technological advances of recent years is experiencing a renaissance that may soon answer one of the greatest scientific questions of this or any age: Are we alone? This paper describes the origins of SETI science, its rocky road to acceptance and some of the bold new ideas and explorations that are pushing the limits of our understanding of the nature of life and intelligence in the Universe.