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{{Short description|Hypothetical megastructure around a star}}

{{Use American English|date=January 2014}}

[[File:Dyson Swarm realistic representation cropped.jpg|thumb|A hypothetical depiction of a Dyson swarm surrounding a star]]

[[File:Freeman dyson (detail).jpg|thumb|[[Freeman Dyson]], the first scientist to explore the concept]]

A '''Dyson sphere''' is a hypothetical [[megastructure]] that encompasses a [[star]] and captures a large percentage of its [[Solar power|power output]].<ref name="Stableford">{{Cite book|last=Stableford|first=Brian M.|title=[[Science Fact and Science Fiction: An Encyclopedia]]|date=2006|publisher=Taylor & Francis|isbn=978-0-415-97460-8|pages=132–133|language=en|chapter=Dyson, Freeman (John) (1923–)|author-link=Brian Stableford|chapter-url=https://books.google.com/books?id=uefwmdROKTAC&pg=132}}</ref><ref name=":1">{{multiref|{{Cite book|last=Westfahl|first=Gary|title=[[Science Fiction Literature through History: An Encyclopedia]]|date=2021-07-19|publisher=ABC-CLIO|isbn=978-1-4408-6617-3|pages=135–136|language=en|chapter=Artificial Worlds|author-link=Gary Westfahl|chapter-url=https://books.google.com/books?id=WETPEAAAQBAJ&pg=PA135}}|{{Cite book|last=Westfahl|first=Gary|title=[[Science Fiction Literature through History: An Encyclopedia]]|date=2021-07-19|publisher=ABC-CLIO|isbn=978-1-4408-6617-3|pages=603|language=en|chapter=Stars|author-link=Gary Westfahl|chapter-url=https://books.google.com/books?id=WETPEAAAQBAJ&pg=PA603}}}}</ref><ref name=":2">{{Cite web|editor-last=Clute|editor-first=John|editor-link=John Clute|editor2-last=Langford|editor2-first=David|editor2-link=David Langford|editor3-last=Sleight|editor3-first=Graham|editor3-link=Graham Sleight|title=Dyson Sphere|url=https://sf-encyclopedia.com/entry/dyson_sphere|url-status=live|access-date=2021-11-18|website=[[The Encyclopedia of Science Fiction]]|edition=4th|archive-url=https://web.archive.org/web/20111028085601/http://www.sf-encyclopedia.com/entry/dyson_sphere |archive-date=2011-10-28 }}</ref> The concept is a [[thought experiment]] that attempts to imagine how a [[spacefaring]] civilization would meet its energy requirements once those requirements exceed what can be generated from the home planet's resources alone. Because only a tiny fraction of a star's energy emissions reaches the surface of any orbiting [[planet]], building structures encircling a star would enable a [[civilization]] to harvest far more energy.

The first modern imagining of such a structure was by [[Olaf Stapledon]] in his science fiction novel ''[[Star Maker]]'' (1937). The concept was later explored by the physicist [[Freeman Dyson]] in his 1960 paper "Search for Artificial Stellar Sources of [[Infrared Radiation]]". Dyson speculated that such structures would be the logical consequence of the escalating energy needs of a technological civilization and would be a necessity for its long-term survival. A signature of such spheres detected in astronomical searches would be an indicator of [[extraterrestrial intelligence]].

Since Dyson's paper, many variant designs involving an artificial structure or series of structures to encompass a star have been proposed in [[exploratory engineering]] or described in [[science fiction]], often under the name "Dyson sphere". Fictional depictions often describe a solid shell of [[matter]] enclosing a star{{snd}}an arrangement considered by Dyson himself to be impossible.

==Origins==
{{See also|Energy development}}
Inspired by the 1937 [[science fiction]] novel ''[[Star Maker]]'' by [[Olaf Stapledon]],<ref>{{cite book |last=Dyson |first=Freeman |title=Disturbing the Universe |publisher=Basic Books |year=1979 |isbn=978-0-465-01677-8 |page=211 |quote=Some science fiction writers have wrongly given me the credit of inventing the artificial biosphere. In fact, I took the idea from Olaf Stapledon, one of their own colleagues}}</ref> the physicist and mathematician [[Freeman Dyson]] was the first to formalize the concept of what became known as the "Dyson sphere" in his 1960 ''[[Science (journal)|Science]]'' paper "Search for Artificial Stellar Sources of Infra-Red Radiation". Dyson theorized that as the energy requirements of an advanced technological civilization increased, there would come a time when it would need to systematically harvest the energy from its local star on a large scale. He speculated that this could be done via a system of structures orbiting the star, designed to intercept and collect its energy. He argued that as the structure would result in the large-scale conversion of starlight into [[Far infrared|far-infrared]] radiation, an earth-based search for sources of infrared radiation could identify stars supporting intelligent life.<ref name="search">{{cite journal |author=Freeman J. Dyson |author-link=Freeman Dyson |year=1960 |title=Search for Artificial Stellar Sources of Infrared Radiation |url=https://www.science.org/doi/10.1126/science.131.3414.1667 |journal=[[Science (journal)|Science]] |volume=131 |issue=3414 |pages=1667–1668 |bibcode=1960Sci...131.1667D |doi=10.1126/science.131.3414.1667 |pmid=17780673 |s2cid=3195432}}</ref>

Dyson did not detail how such a system could be constructed, simply referring to it in the paper as a "shell" or "[[biosphere]]". He later clarified that he did not have in mind a solid structure, saying: "A solid shell or ring surrounding a star is mechanically impossible. The form of 'biosphere' which I envisaged consists of a loose collection or swarm of objects traveling on independent orbits around the star."<ref>{{cite journal |last1=Dyson |first1=F. J. |last2=Maddox |first2=J. |last3=Anderson |first3=P |last4=Sloane |first4=E. A. |year=1960 |title=Letters and Response, Search for Artificial Stellar Sources of Infrared Radiation |journal=[[Science (journal)|Science]] |volume=132 |issue=3421 |pages=250–253 |doi=10.1126/science.132.3421.252-a |pmid=17748945}}</ref> Such a concept has often been referred to as a '''Dyson swarm''';<ref>{{cite journal |last1=Smith |first1=Jack |year=2020 |title=Review and viability of a Dyson Swarm as a form of Dyson Sphere |journal=[[Physica Scripta]] |volume=97 |number=12 |page=122001 |doi=10.1088/1402-4896/ac9e78|s2cid=237605010 |doi-access=free |arxiv=2109.11443 }}</ref> however, in 2013, Dyson said he had come to regret that the concept had been named after him.<ref>{{cite web |date=7 July 2013 |title=STARSHIP CENTURY SYMPOSIUM, MAY 21–22, 2013 |url=http://starshipconf.ucsd.edu/ |url-status=dead |archive-url=https://web.archive.org/web/20130707123030/http://starshipconf.ucsd.edu/ |archive-date=7 July 2013 |access-date=31 August 2017}}</ref>

==Search for megastructures==
Dyson-style energy collectors around a distant star would absorb and re-radiate energy from the star. The wavelengths of such re-radiated energy may be atypical for the star's [[spectral type]], due to the presence of heavy elements not naturally occurring within the star. If the percentage of such atypical wavelengths were to be significant, an alien megastructure could be detected at interstellar distances.<ref name="search" /> This could indicate the presence of what has been called a Type{{nbs}}II [[Kardashev scale|Kardashev civilization]].<ref>{{cite conference |first=Nikolai |last=Kardashev |author-link=Nikolai Kardashev |url=http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1985IAUS..112..497K |title=On the Inevitability and the Possible Structures of Supercivilizations |conference=The search for extraterrestrial life: Recent developments; Proceedings of the Symposium, June 18–21, 1984 |location=Boston, Massachusetts, US |id=A86-38126 17–88 |publisher=Dordrecht, D. Reidel Publishing Co. |date=1985 |pages=497–504|bibcode=1985IAUS..112..497K }}</ref>

[[SETI]] has looked for such infrared-heavy spectra from [[solar analog]]s, as has [[Fermilab]].<ref name="dyson1">{{cite web| url=http://home.fnal.gov/~carrigan/infrared_astronomy/Fermilab_search.htm| title=Fermilab Dyson Sphere search program|date=February 23, 2006| access-date=2006-03-02| first=D.| last=Carrigan| publisher=Fermi National Accelerator Laboratory|archive-url=https://web.archive.org/web/20060306222359/http://home.fnal.gov/~carrigan/Infrared_Astronomy/Fermilab_search.htm| archive-date=2006-03-06| url-status=dead}}</ref><ref>{{Cite journal |last=Shostak |first=Seth |date=Spring 2009 |journal=Engineering & Science |title=When Will We Find the Extraterrestrials? |volume=72 |number=1 |pages=12–21 |issn=0013-7812 |url=http://archive.seti.org/pdfs/Shostak-spring2009-EnS.pdf <!--permalink to official source with abstract & alternate PDF link: http://resolver.caltech.edu/CaltechES:72.1.Extraterrestrials--> |url-status=dead |archive-url=https://web.archive.org/web/20150415115307/http://archive.seti.org/pdfs/Shostak-spring2009-EnS.pdf |archive-date=2015-04-15 }}</ref> Fermilab discovered 17 potential "ambiguous" candidates, of which four were in 2006 called "amusing but still questionable".<ref name="dyson1" /> Later searches also resulted in several candidates, all of which remain unconfirmed.<ref>{{cite web|author=Dick Carrigan |url=http://home.fnal.gov/~carrigan/infrared_astronomy/Other_searches.htm |title=Dyson Sphere Searches |publisher=Home.fnal.gov |date=2010-12-16 |access-date=2012-06-12}}</ref><ref>{{cite web|url=http://www.scientificamerican.com/article/alien-supercivilizations-absent-from-100-000-nearby-galaxies|title=Alien Supercivilizations Absent from 100,000 Nearby Galaxies|first=Lee|last=Billings|website=[[Scientific American]]|access-date=31 August 2017}}</ref><ref name="econ2015">{{Cite news
| title = Infra digging: Looking for aliens: The search for extraterrestrials goes intergalactic
| newspaper = The Economist
| date = 2015-04-18
| access-date = 2015-04-19
| url = https://www.economist.com/news/science-and-technology/21648607-search-extraterrestrials-goes-intergalactic-infra-digging
| quote = Fifty [galaxies] were red enough to be hosting aliens gobbling up half or more of their starlight.
}}</ref>

On 14 October 2015, [[Planet Hunters]]' citizen scientists discovered unusual light fluctuations of the star [[KIC 8462852]] raising press speculation that a Dyson sphere may have been discovered.<ref name="ATL-20151013">{{cite web| last1=Andersen| first1=Ross| title=The Most Mysterious Star in Our Galaxy| url=https://www.theatlantic.com/science/archive/2015/10/the-most-interesting-star-in-our-galaxy/410023/ |date=13 October 2015 |work=[[The Atlantic]]| access-date=13 October 2015}}</ref><ref name="IND-20151015">{{cite web| last1=Williams| first1=Lee| title=Astronomers may have found giant alien 'megastructures' orbiting star near the Milky Way| url=https://www.independent.co.uk/news/world/forget-water-on-mars-astronomers-may-have-just-found-giant-alien-megastructures-orbiting-a-star-near-a6693886.html |date=15 October 2015 |work=[[The Independent]]| access-date=15 October 2015}}</ref> However, subsequent analysis showed that the results were consistent with the presence of dust.<ref name="AXV-20180102">{{Cite journal |title=The First Post-Kepler Brightness Dips of KIC 8462852 |journal=The Astrophysical Journal |volume=853 |issue=1 |at=L8 |arxiv=1801.00732 |first1=Tabetha S. |last1=Boyajian |display-authors=etal |doi=10.3847/2041-8213/aaa405 |year=2018 |bibcode=2018ApJ...853L...8B|s2cid=215751718 |doi-access=free }}</ref><ref name="NatGeoJan3">{{cite news |url=https://news.nationalgeographic.com/2018/01/mystery-of--alien-megastructure--star-has-been-cracked/ |archive-url=https://web.archive.org/web/20180103214909/https://news.nationalgeographic.com/2018/01/mystery-of--alien-megastructure--star-has-been-cracked/ |url-status=dead |archive-date=January 3, 2018 |title=Mystery of 'Alien Megastructure' Star Has Been Cracked |work=[[National Geographic]] |last=Drake |first=Nadia |author-link=Nadia Drake |date=3 January 2018 |access-date=4 January 2018}}</ref>A further campaign in 2024 identified seven possible candidates for Dyson-spheres, but further investigation was said to be required.<ref>{{Cite web |last=Hrinko |first=Ivan |date=2024-05-14 |title=Scientists start hunting for Dyson Spheres |url=https://universemagazine.com/en/scientists-find-seven-candidates-for-dyson-spheres/ |access-date=2024-07-15 |website=Universe Space Tech |language=en-US}}</ref><ref>{{cite journal |last1=Suazo |first1=Matías |display-authors=et al |date=6 May 2024 |title=Project Hephaistos – II. Dyson sphere candidates from Gaia DR3, 2MASS, and WISE |url=https://academic.oup.com/mnras/article/531/1/695/7665761?login=false |journal=Monthly Notices of the Royal Astronomical Society |volume=531 |issue=1 |pages=695–707 |arxiv=2405.02927 |doi=10.1093/mnras/stae1186 |doi-access=free}}</ref>

==Feasibility and science-based speculation==
Although Dyson sphere systems are theoretically possible, building a stable megastructure around the Sun is currently far beyond humanity's engineering capacity. The number of craft required to obtain, transmit, and maintain a complete Dyson sphere exceeds present-day industrial capabilities. [[George Dvorsky]] has advocated the use of [[self-replicating robots]] to overcome this limitation in the relatively near term.<ref name="dvorsky2012">{{cite web |last1=Dvorsky |first1=George |date=2012-03-20 |title=How to build a Dyson sphere in five (relatively) easy steps |url=http://www.sentientdevelopments.com/2012/03/how-to-build-dyson-sphere-in-five.html |access-date=2016-10-07}}</ref> Some have suggested that Dyson sphere habitats could be built around [[white dwarf#Habitability|white dwarf]]s<ref>{{cite arXiv |eprint=1503.04376 |class=physics.pop-ph |first1=İbrahim |last1=Semiz |first2=Salim |last2=Oğur |title=Dyson Spheres around White Dwarfs |year=2015}}</ref> and even [[pulsar]]s.<ref>{{cite journal |last1=Osmanov |first1=Z. |year=2015 |title=On the search for artificial Dyson-like structures around pulsars |journal=Int. J. Astrobiol. |volume=15 |issue=2 |pages=127–132 |arxiv=1505.05131 |bibcode=2016IJAsB..15..127O |doi=10.1017/S1473550415000257 |s2cid=13242388}}</ref>

[[Stellar engine]]s are hypothetical megastructures whose purpose is to extract useful energy from a star, sometimes for specific purposes. For example, [[Matrioshka brain]]s have been proposed to extract energy for computation, while [[Stellar engine#Class A (Shkadov thruster)|Shkadov thrusters]] would extract energy for propulsion. Some proposed stellar engine designs are based on the Dyson sphere.<ref>{{cite encyclopedia |title=Stellar engine |encyclopedia=The Internet Encyclopedia of Science |url=http://www.daviddarling.info/encyclopedia/S/stellar_engine.html |access-date=2007-10-08}}</ref><ref>{{cite web |last1=Badescu |first1=Viorel |first2=Richard B. |last2=Cathcart |title=Space travel with solar power and a dyson sphere |url=http://www.astronomytoday.com/exploration/solartravel.html |access-date=2007-10-07 |work=Astronomy Today |archive-date=2012-02-04 |archive-url=https://web.archive.org/web/20120204090100/http://www.astronomytoday.com/exploration/solartravel.html |url-status=dead }}</ref>

From May until June 2024, speculation grew that potential signs of interstellar Dyson spheres had been discovered. The seven objects of interest{{snd}}all located within a thousand light-years of Earth{{snd}}are [[Red dwarf|M-dwarfs]], a class of stars that are smaller and less luminous than the Sun. However, the authors of the findings were careful not to make any overblown claims.<ref>{{Cite web |last=Goodwin |first=Simon |date=2024-05-22 |title=Dyson spheres: astronomers report potential candidates for alien megastructures – here's what to make of it |url=http://theconversation.com/dyson-spheres-astronomers-report-potential-candidates-for-alien-megastructures-heres-what-to-make-of-it-230364 |access-date=2024-06-25 |website=The Conversation |language=en-US}}</ref> Despite this, many media outlets picked up on the story. Less fantastical alternative explanations have been made, including a proposal that the infrared from the discoveries was caused by distant dust-obscured galaxies.<ref>{{Cite web |first=Paul |last=Sutter |date=2024-06-10 |title=7 potential 'alien megastructures' spotted in our galaxy are not what they seem |url=https://www.livescience.com/space/extraterrestrial-life/7-potential-alien-megastructures-spotted-in-our-galaxy-are-not-what-they-seem |access-date=2024-06-25 |website=livescience.com |language=en}}</ref><ref>{{Cite web |last=Today |first=Universe |date=2024-06-01 |title=Mysterious Dyson Spheres Could Have Another Explanation, Scientists Say |url=https://www.sciencealert.com/mysterious-dyson-spheres-could-have-another-explanation-scientists-say |access-date=2024-06-25 |website=ScienceAlert |language=en-US}}</ref><ref>{{Cite AV media |url=https://www.youtube.com/watch?v=bCi7T1z7FaE |title=New study finds potential alien mega-structures known as 'dyson spheres' |date=2024-06-14 |last=NBC News |access-date=2024-06-25 |via=YouTube}}</ref>

==Fictional examples==
A precursor to the concept of Dyson spheres was featured in the 1937 novel ''[[Star Maker]]'' by [[Olaf Stapledon]],<ref name="Stableford" /> in which he described "every solar system... surrounded by a gauze of light-traps, which focused the escaping solar energy for intelligent use";<ref>{{cite web |last1=Tate |first1=Karl |date=14 January 2014 |title=Dyson Spheres: How Advanced Alien Civilizations Would Conquer the Galaxy |url=https://www.space.com/24276-dyson-spheres-how-advanced-alien-civilizations-would-conquer-the-galaxy-infographic.html |access-date=January 14, 2014 |website=[[Space.com]]}}</ref> Dyson got his inspiration from this book and suggested that "Stapledon sphere" would be a more apt name for the concept.<ref>{{Cite encyclopedia |year=2022 |title=Dyson, Freeman J |encyclopedia=[[The Encyclopedia of Science Fiction]] |url=https://sf-encyclopedia.com/entry/dyson_freeman_j |access-date=2024-03-20 |edition=4th |author1-last=Sudbery|author1-first=Tony |author2-last=Langford |author2-first=David |author2-link=David Langford |editor1-last=Clute |editor1-first=John |editor1-link=John Clute |editor2-last=Langford |editor2-first=David |editor2-link=David Langford |editor3-last=Sleight |editor3-first=Graham |editor3-link=Graham Sleight}}</ref> Fictional Dyson spheres are typically solid structures forming a continuous shell around the star in question, although Dyson himself considered that prospect to be mechanically implausible.<ref name=":1" /><ref name=":2" /> They are sometimes used as the type of plot device known as a [[Big Dumb Object]].<ref name=":3" />

Dyson spheres appear as a background element in many works of fiction, including the 1964 novel ''[[The Wanderer (Leiber novel)|The Wanderer]]'' by [[Fritz Leiber]] where [[Extraterrestrial life|aliens]] enclose multiple stars in this way.<ref name="Stableford" /><ref name=":3">{{Cite book |last= |first= |url= |title=The Ultimate Encyclopedia of Science Fiction: The Definitive Illustrated Guide |date=1997 |publisher=Carlton |isbn=978-1-85868-385-0 |editor-last=Pringle |editor-first=David |editor-link=David Pringle |pages=50 |language=en |chapter=Space Habitats |author-link= |chapter-url=https://archive.org/details/ultimateencyclop0000unse_a8c7/page/50/mode/2up}}</ref><ref>{{Cite book |last=Stableford |first=Brian |url=https://archive.org/details/sciencefictionwr0000unse |title=Science Fiction Writers: Critical Studies of the Major Authors from the Early Nineteenth Century to the Present Day |date=1999 |publisher=[[Charles Scribner's Sons]] |isbn=0-684-80593-6 |editor-last=Bleiler |editor-first=Richard |editor-link=Richard Bleiler |edition=2nd |location=New York |page=441 |chapter=Fritz Leiber |oclc=40460120 |author-link=Brian Stableford}}</ref> Dyson spheres are depicted in the 1975–1983 book series ''[[Saga of Cuckoo]]'' by [[Frederik Pohl]] and [[Jack Williamson]], and one functions as the [[Setting (narrative)|setting]] of [[Bob Shaw]]'s 1975 novel ''[[Orbitsville]]'' and its sequels.<ref name=":1" /><ref name=":2" /> In the 1992 episode "[[Relics (Star Trek: The Next Generation)|Relics]]" of the TV show ''[[Star Trek: The Next Generation]]'',<ref>{{cite web |last=Hadhazy |first=Adam |date=October 30, 2020 |title=Could We Build a Dyson Sphere? |url=https://www.popularmechanics.com/space/deep-space/a11098/dyson-sphere/ |archiveurl=https://web.archive.org/web/20210310182228/https://www.popularmechanics.com/space/deep-space/a11098/dyson-sphere/ |archivedate=March 10, 2021 |access-date=March 20, 2024 |website=[[Popular Mechanics]]}}</ref> the {{USS|Enterprise|NCC-1701-D|6}} finds itself trapped in an abandoned Dyson Sphere;<ref>{{Cite web |last=Howell |first=Elizabeth |date=March 12, 2020 |title='Dyson sphere' legacy: Freeman Dyson's wild alien megastructure idea will live forever |url=https://www.space.com/freeman-dyson-sphere-sci-fi-seti-legacy.html |access-date=March 20, 2024 |website=[[Space.com]]}}</ref><ref>{{cite book |author1-link=Larry Nemecek |last1=Nemecek |first1=Larry |title=Star Trek: The Next Generation Companion |edition=3rd |publisher=[[Pocket Books]] |year=2003 |pages=218–220}}</ref> in a 2011 interview, Dyson said that he enjoyed the episode, although he considered the sphere depicted to be "nonsense".<ref>{{cite web |last=Wright |first=Robert |author-link=Robert Wright (journalist) |date=2011 |title=MeaningofLife.tv |url=http://meaningoflife.tv/transcript.php?speaker=dyson |url-status=dead |archive-url=https://web.archive.org/web/20110820213611/http://meaningoflife.tv/transcript.php?speaker=dyson |archive-date=20 August 2011 |access-date=20 March 2024 |website=slate.com |publisher=[[Slate (magazine)|Slate]] |quote=Wright: Did they actually use the phrase 'Dyson sphere' on ''Star Trek''?<br>Freeman Dyson: Oh yes.<br>Wright: Did they really?<br>Freeman Dyson: One of my daughters sent me a tape of that program afterwards and so I watched it. Oh yes, it's very clearly labeled and actually it was sort of fun to watch it, but it's all nonsense. But it's quite a good piece of cinema. [punctuation supplied for unedited transcript] }}</ref>
[[Michael Jan Friedman]] who wrote the novelization observed that in the TV episode itself the Dyson sphere was effectively a [[MacGuffin]], with "just nothing about it" in the story, and decided to flesh out the plot element in his novelization.<ref name="Ayers2006">{{cite book|title=Voyages of Imagination: The Star Trek Fiction Companion|author1-first=Jeff|author1-last=Ayers|publisher=Simon and Schuster|year=2006|isbn=9781416525486}}</ref>{{rp|ix}}

Other science-fiction story examples include [[Tony Rothman]]'s ''The World Is Round'', [[S. P. Somtow|Somtow Sucharitkul]]'s Inquisitor series, [[Timothy Zahn]]'s ''Spinneret'', [[James White (author)|James White]]'s ''Federation World'', [[Stephen Baxter (author)|Stephen Baxter]]'s ''[[The Time Ships]]'', and [[Peter F. Hamilton]]'s ''Pandora's Star''.<ref name="Stableford"/>{{rp|133}} Variations on the Dyson Sphere concept include a single circular band in [[Larry Niven]]'s 1970 novel ''[[Ringworld]]'',<ref name=":2" /><ref>{{Cite book|last=Nicholls|first=Peter|title=[[The Science in Science Fiction]]|date=1983|publisher=Knopf|isbn=0-394-53010-1|editor-last=Nicholls|editor-first=Peter|editor-link=Peter Nicholls (writer)|location=New York|pages=44–45|chapter=Far-future energy|oclc=8689657|author-link=Peter Nicholls (writer)|chapter-url=https://archive.org/details/scienceinscience00nich/page/44/mode/2up}}</ref><ref>{{Cite book|last=Mann|first=George |title=The Mammoth Encyclopedia of Science Fiction|date=2001|publisher=Carroll & Graf Publishers|isbn=978-0-7867-0887-1|location=New York|pages=477|chapter=Dyson Sphere|author-link=George Mann (writer)|chapter-url=https://archive.org/details/mammothencyclope00mann/page/477/mode/2up}}</ref> a half sphere in the 2012 novel ''[[Bowl of Heaven]]'' by [[Gregory Benford]] and Niven,<ref name=":1" /><ref name=":2" /> and nested spheres{{snd}}also known as a [[Matrioshka brain]]{{snd}}in [[Colin Kapp]]'s 1980s [[Cageworld series|''Cageworld'' series]] and [[Brian Stableford]]'s 1979–1990 [[Brian Stableford#Asgard|''Asgard'' trilogy]].<ref name="Stableford" /><ref name=":2" />

Stableford himself observed that Dyson spheres are usually MacGuffins or largely deep in the backgrounds of stories, giving as examples [[Fritz Leiber]]'s ''The Wanderer'' and [[Linda Nagata]]'s ''Deception Well'', whereas stories involving space exploration tend to employ the variants like Niven's Ringworld.<ref name="Stableford" />{{rp|133}}He gives two reasons for this: firstly that Dyson spheres are simply too big to address, which Friedman also alluded to when pointing out that the reason his novelization of "Relics" did not go further into the sphere was that it was only four hundred pages and he had just shy of four weeks to write it; and secondly that, especially for hard science-fiction, Dyson spheres have certain engineering problems that complicate stories.<ref name="Stableford"/>{{rp|133}}<ref name="Ayers2006"/>{{rp|ix}} In particular, since gravitational attraction is in equilibrium inside such a sphere (per the [[shell theorem]]), other means such as rotating the sphere have to be employed in order to keep things attached to the interior surface, which then leads to the problem of a gravity gradient that goes to zero at the rotational poles.<ref name="Stableford"/>{{rp|133}} Authors address this with various modifications of the idea such as the aforementioned Cageworld nesting, [[Dan Alderson]]'s double sphere idea, and Niven's reduced Ringworld (discussed in "[[Bigger Than Worlds]]").<ref name="Stableford"/>{{rp|133}}

==See also==
<!--please maintain alphabetical order-->
*{{annotated link|Alderson disk}}
*{{annotated link|List of hypothetical technologies}}
*{{annotated link|Stellar engineering}}
*{{annotated link|Tabby's Star}}

==References==
{{Reflist}}

==Further reading==
*{{Cite web |last=Gunn |first=Alastair |date=2022-12-29 |title=Dyson spheres: How humans (and aliens) could capture a star's energy |url=https://www.sciencefocus.com/space/dyson-spheres |url-status=live |archive-url=https://web.archive.org/web/20240311084233/https://www.sciencefocus.com/space/dyson-spheres |archive-date=2024-03-11 |access-date=2024-03-20 |website=[[BBC Science Focus]] |language=en}}
*{{Cite web |last=Mann |first=Adam |date=2019-08-01 |title=What is a Dyson sphere? |url=https://www.space.com/dyson-sphere.html |url-status=live |archive-url=https://web.archive.org/web/20240307200946/https://www.space.com/dyson-sphere.html |archive-date=2024-03-07 |access-date=2024-03-20 |website=[[Space.com]] |language=en}}
*{{Cite web |last=Schulze-Makuch |first=Dirk |author-link=Dirk Schulze-Makuch |date=2014-01-29 |title=Dyson Spheres: Still Missing, Maybe Impossible |url=https://www.smithsonianmag.com/air-space-magazine/dyson-spheres-still-missing-maybe-impossible-180949538/ |url-status=live |archive-url=https://web.archive.org/web/20230928170349/https://www.smithsonianmag.com/air-space-magazine/dyson-spheres-still-missing-maybe-impossible-180949538/ |archive-date=2023-09-28 |access-date=2024-03-20 |website=[[Smithsonian Magazine]] |language=en}}
*{{Cite book |last=Stableford |first=Brian |author-link=Brian Stableford |title=Historical Dictionary of Science Fiction Literature |date=2004 |publisher=Scarecrow Press |isbn=978-0-8108-4938-9 |pages=99 |language=en |chapter=Dyson Sphere |chapter-url=https://books.google.com/books?id=nzmIPZg5xicC&pg=PA99}}
*{{Cite web |last=Stanway |first=Elizabeth |author-link=<!--No article at present (July 2024); Stanway is an astrophysicist at the University of Warwick who has been published in [[Foundation (journal)]], among others (see https://warwick.ac.uk/fac/sci/physics/research/astro/people/stanway/sciencefiction); Wikidata Q127710708--> |date=2023-05-21 |title=Megastructures |url=https://warwick.ac.uk/fac/sci/physics/research/astro/people/stanway/sciencefiction/cosmicstories/megastructures |url-status=live |archive-url=https://web.archive.org/web/20230526080458/https://warwick.ac.uk/fac/sci/physics/research/astro/people/stanway/sciencefiction/cosmicstories/megastructures |archive-date=2023-05-26 |access-date=2024-03-25 |website=[[Warwick University]] |series=Cosmic Stories Blog}}

==External links==
{{Wiktionary|Dyson sphere}}
{{Commons category|Dyson sphere}}
*[https://www.aleph.se/Nada/dysonFAQ.html Dyson sphere FAQ]
*[http://iopscience.iop.org/0004-637X/698/2/2075/pdf/0004-637X_698_2_2075.pdf FermiLab: IRAS-based whole sky upper limit on Dyson spheres] with an appendix on Dyson sphere engineering

{{Memory Alpha|Dyson sphere}}
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