Editing Space colonization (section)

====Survival of human civilization====
{{Main|Space and survival}}

A primary argument calling for space colonization is the long-term survival of human civilization and terrestrial life.<ref>{{Cite web|last=Piper|first=Kelsey|date=22 October 2018|title=Jeff Bezos and Elon Musk want to colonize space to save humanity|url=https://www.vox.com/future-perfect/2018/10/22/17991736/jeff-bezos-elon-musk-colonizing-mars-moon-space-blue-origin-spacex|access-date=2 April 2021|website=Vox|language=en}}</ref> By developing alternative locations off Earth, the planet's species, including humans, could live on in the event of [[Global catastrophic risk|natural or human-made disasters on Earth]].<ref>{{cite book |last=Kaku |first=Michio |author-link=Michio Kaku |title=The Future of Humanity: Terraforming Mars, Interstellar Travel, Immortality, and Our Destiny Beyond Earth |publisher=Doubleday |year=2018 |isbn=978-0385542760 |pages=3–6 |quote=It is as inescapable as the laws of physics that humanity will one day confront some type of [[extinction]]-level [[Extinction event|event]]. ... [W]e face threats [that include] [[global warming]] ... [[Biological warfare|weaponized microbes]] ... [[Quaternary glaciation|the onset of another ice age]] ... the possibility that [[Yellowstone Caldera|the supervolcano under Yellowstone National Park]] may awaken from its long slumber ... [and] another [[Impact event|meteor or cometary impact]] . ... [from one of the] several thousand [[Near-Earth object|NEOs (near-Earth objects)]] that cross the orbit of the Earth. ... Life is too precious to be placed on a single planet . ... Perhaps our fate is to become a multiplanet species that lives [[Interstellar travel|among the stars]].}}</ref>

On two occasions, theoretical physicist and cosmologist [[Stephen Hawking]] argued for space colonization as a means of saving humanity. In 2001, Hawking predicted that the human race would become extinct within the next thousand years unless colonies could be established in space.<ref>{{cite news |last=Highfield |first=Roger |url=https://www.telegraph.co.uk/news/uknews/1359562/Colonies-in-space-may-be-only-hope-says-Hawking.html |title=Colonies in space may be only hope, says Hawking |work=The Telegraph |date=16 October 2001 |access-date=5 August 2012 |archive-url=https://web.archive.org/web/20090426232042/http://www.telegraph.co.uk/news/uknews/1359562/Colonies-in-space-may-be-only-hope-says-Hawking.html |archive-date=26 April 2009 |url-status=live}}</ref> In 2010, he stated that humanity faces two options: either we colonize space within the next two hundred years, or we will face the long-term prospect of [[Human extinction|extinction]].<ref>{{cite news|agency=Press Association|date=9 August 2010|title=Stephen Hawking: mankind must colonise space or die out |first=Stephen|last=Hawking|language=en-GB|work=The Guardian|url=https://www.theguardian.com/science/2010/aug/09/stephen-hawking-human-race-colonise-space|access-date=20 June 2020|issn=0261-3077}}</ref>

In 2005, then [[NASA]] Administrator [[Michael D. Griffin|Michael Griffin]] identified space colonization as the ultimate goal of current spaceflight programs, saying:
{{blockquote|...&nbsp;the goal isn't just scientific exploration&nbsp;... it's also about extending the range of human habitat out from Earth into the solar system as we go forward in time&nbsp;... In the long run, a single-planet species will not survive&nbsp;... If we humans want to survive for hundreds of thousands of millions of years, we must ultimately populate other planets. Now, today the technology is such that this is barely conceivable. We're in the infancy of it.&nbsp;... I'm talking about that one day, I don't know when that day is, but there will be more human beings who live off the Earth than on it. We may well have people living on the Moon. We may have people living on the moons of Jupiter and other planets. We may have people making habitats on asteroids&nbsp;... I know that humans will colonize the solar system and one day go beyond.<ref>{{cite news| url=https://www.washingtonpost.com/wp-dyn/content/article/2005/09/23/AR2005092301691.html| title=NASA's Griffin: 'Humans Will Colonize the Solar System'| date=25 September 2005| newspaper=Washington Post| page=B07| access-date=14 September 2017| archive-url=https://web.archive.org/web/20110604141654/http://www.washingtonpost.com/wp-dyn/content/article/2005/09/23/AR2005092301691.html| archive-date=4 June 2011| url-status=live}}</ref>|sign=|source=}}

[[Louis J. Halle Jr.]], formerly of the [[United States Department of State]], wrote in ''[[Foreign Affairs]]'' (Summer 1980) that the colonization of space will protect humanity in the event of global [[nuclear warfare]].<ref>{{cite journal |url=http://www.foreignaffairs.org/19800601faessay8146/louis-j-halle/a-hopeful-future-for-mankind.html |title=A Hopeful Future for Mankind |first=Louis J. |last=Halle |journal=Foreign Affairs |date=Summer 1980 |doi=10.2307/20040585 |volume=58 |issue=5 |pages=1129–36 |url-status=dead |archive-url=https://web.archive.org/web/20041013051342/http://www.foreignaffairs.org/19800601faessay8146/louis-j-halle/a-hopeful-future-for-mankind.html |archive-date=13 October 2004 |jstor=20040585|url-access=subscription }}</ref> The physicist [[Paul Davies]] also supports the view that if a planetary catastrophe threatens the survival of the human species on Earth, a self-sufficient colony could "reverse-colonize" Earth and restore [[Civilization|human civilization]]. The author and journalist [[William E. Burrows]] and the biochemist [[Robert Shapiro (chemist)|Robert Shapiro]] proposed a private project, the [[Alliance to Rescue Civilization]], with the goal of establishing an off-Earth "[[backup]]" of human civilization.<ref>{{cite news |url=https://www.nytimes.com/2006/08/01/science/01arc.html |title=Life After Earth: Imagining Survival Beyond This Terra Firma |newspaper=The New York Times |first=Richard |last=Morgan |date=1 August 2006 |access-date=23 May 2010 |archive-url=https://web.archive.org/web/20090417023904/http://www.nytimes.com/2006/08/01/science/01arc.html |archive-date=17 April 2009 |url-status=live}}</ref>

Based on his [[Copernican principle]], [[J. Richard Gott]] has estimated that the human race could survive for another 7.8&nbsp;million years, but it is not likely to ever colonize other planets. However, he expressed a hope to be proven wrong, because "colonizing other worlds is our best chance to hedge our bets and improve the survival prospects of our species".<ref>{{cite news |last=Tierney |first=John |url=https://www.nytimes.com/2007/07/17/science/17tier.html?ex=1342324800&en=ccf375ae9f268470&ei=5090&partner=rssuserland&emc=rss |title=A Survival Imperative for Space Colonization |date=17 July 2007 |work=The New York Times |access-date=23 February 2017 |archive-url=https://web.archive.org/web/20170629081936/http://www.nytimes.com/2007/07/17/science/17tier.html?ex=1342324800&en=ccf375ae9f268470&ei=5090&partner=rssuserland&emc=rss |archive-date=29 June 2017 |url-status=live}}</ref>

In a theoretical study from 2019, a group of researchers have pondered the long-term trajectory of human civilization.<ref name=sb01>{{cite journal |last=Baum |first=Seth D. |author-link=Seth Baum |display-authors=etal |date=2019 |title=Long-Term Trajectories of Human Civilization |url=http://gcrinstitute.org/papers/trajectories.pdf |journal=Foresight |volume=21 |issue=1 |location=Bingley |publisher=Emerald Group Publishing |doi=10.1108/FS-04-2018-0037 |pages=53–83 |s2cid=52042667 |access-date=23 September 2019 |archive-url=https://web.archive.org/web/20200102042937/http://gcrinstitute.org/papers/trajectories.pdf |archive-date=2 January 2020 |url-status=live}}</ref> It is argued that due to Earth's finitude as well as the [[Formation and evolution of the Solar System#The Sun and planetary environments|limited duration of the Solar System]], mankind's survival into the far future will very likely require extensive space colonization.<ref name=sb01/>{{rp|8, 22f}} This 'astronomical trajectory' of mankind, as it is termed, could come about in four steps: First step, space colonies could be established at various habitable locations — be it in outer space or on [[Astronomical object|celestial bodies]] away from Earth – and allowed to remain temporarily dependent on support from Earth. In the second step, these colonies could gradually become self-sufficient, enabling them to survive if or when the mother civilization on Earth fails or dies. Third step, the colonies could develop and expand their habitation by themselves on their [[space station]]s or celestial bodies, for example via [[terraforming]]. In the fourth step, the colonies could self-replicate and establish new colonies further into space, a process that could then repeat itself and continue at an [[Exponential growth|exponential rate]] throughout the cosmos. However, this astronomical trajectory may not be a lasting one, as it will most likely be interrupted and eventually decline due to resource depletion or straining competition between various human factions, bringing about some 'star wars' scenario.<ref name=sb01/>{{rp|23–25}}