Editing Extraterrestrial intelligence (section)

==Probability==
The [[Copernican principle]] is generalized to the [[Theory of relativity|relativistic]] concept that humans are not privileged observers of the universe.<ref>{{Cite book |last=Peacock |first=John A. |url=https://archive.org/details/cosmologicalphys0000peac |title=Cosmological Physics |publisher=[[Cambridge University Press]] |year=1998 |isbn=0-521-42270-1 |page=[https://archive.org/details/cosmologicalphys0000peac/page/66 66] |url-access=registration}}</ref>  Many prominent scientists, including [[Stephen Hawking]]<ref name="Auto2J-30">{{Cite news |last=Hickman |first=Leo |date=25 April 2010 |title=Stephen Hawking takes a hard line on aliens |url=https://www.theguardian.com/commentisfree/2010/apr/26/stephen-hawking-issues-warning-on-aliens |access-date=24 February 2012 |work=[[The Guardian]]}}</ref> have proposed that the sheer scale of the universe makes it improbable for intelligent life not to have emerged elsewhere.  However, [[Fermi's Paradox]] highlights the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilization and humanity's lack of contact with, or [[evidence]] for, such civilizations.<ref name=":0">{{Cite news |last=Krauthammer |first=Charles |date=December 29, 2011 |title=Are we alone in the universe? |url=https://www.washingtonpost.com/opinions/are-we-alone-in-the-universe/2011/12/29/gIQA2wSOPP_story.html |access-date=January 6, 2015 |work=[[The Washington Post]]}}</ref>

So far, there is no observation of extraterrestrial life, including intelligent extraterrestrial life.<ref>{{Cite web |last=Kaufman |first=Marc |date=12 October 2022 |title=Life, Here and Beyond |url=https://astrobiology.nasa.gov/about/ |access-date=3 February 2023 |website=NASA Astrobiology |quote="No life beyond Earth has ever been found; there is no evidence that alien life has ever visited our planet. It’s all a story."}}</ref>

The [[Kardashev scale]] is a speculative method of measuring a [[civilization]]'s level of [[technology|technological]] advancement, based on the amount of [[energy]] a civilization is able to utilize.<ref>[[Nikolai Kardashev|Kardashev, Nikolai]]. "[http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1985IAUS..112..497K On the Inevitability and the Possible Structures of Supercivilizations]", The search for extraterrestrial life: Recent developments; Proceedings of the Symposium, Boston, MA, June 18–21, 1984 (A86-38126 17-88). Dordrecht, D. Reidel Publishing Co., 1985, p. 497–504.</ref>

The [[Drake equation]] is a [[probability theory|probabilistic]] framework used to estimate the number of active, communicative extraterrestrial civilizations in the [[Milky Way]] [[galaxy]].<ref name="Wende">{{Cite news |last=Zaun |first=Harald |date=1 November 2011 |title=Es war wie eine 180-Grad-Wende von diesem peinlichen Geheimnis! |trans-title=It was like a 180 degree turn from this embarrassing secret |url=http://www.heise.de/tp/artikel/35/35756/1.html |work=[[Telepolis]] |publisher=Heise |language=de}}</ref>