Extraterrestrial intelligence: Difference between revisions

{{Distinguish|Extraterrestrials in fiction}}

'''Extraterrestrial intelligence''' ('''ETI''') refers to hypothetical [[intelligence|intelligent]] [[extraterrestrial life]]. No such life has ever been verifiably observed to exist.<ref>{{Cite book |last=Bennett |first=Jeffrey |title=Life in the universe |date=2017 |publisher=Pearson |isbn=978-0-13-408908-9 |location=United States |page=3-4}}</ref> The question of whether other inhabited worlds might exist has been debated since ancient times.<ref>Plurality of Worlds: The Extraterrestrial life Debate from Democritus to Kant, by Steven Dick, Cambridge University Press 1984</ref> The modern form of the concept emerged when the [[Copernican Revolution]] demonstrated that the Earth was a planet revolving around the Sun, and other planets were, conversely, other worlds.<ref>The Extraterrestrial Life Debate: 1750-1900, by Michael J. Crowe, Dover Publications, 2011</ref> The question of whether other inhabited planets or moons exist was a natural consequence of this new understanding. It has become one of the most speculative questions in science and is a central theme of science fiction and popular culture.<ref>{{Cite news |last=Spinks |first=Peter |date=May 21, 2013 |title=Are we alone? |url=http://www.smh.com.au/technology/sci-tech/are-we-alone-20130520-2jx69.html |url-access=subscription |work=[[SMH.com.au]]}}</ref>