View source for Infinity symbol

{{Short description|Mathematical symbol, "∞"}}
{{Infobox symbol
|mark=<math>\infty</math>
|name=Infinity symbol
|unicode = {{unichar|221E|Infinity|html=}}
|different from = {{unichar|267E|Permanent paper sign |nlink= Acid-free paper}}<br />{{unichar|26AD|Marriage symbol}}
}}

The '''infinity symbol''' (<span style="font-size:115%; vertical-align:-5%;">{{math|∞}}</span>) is a [[List of mathematical symbols|mathematical symbol]] representing the concept of [[Infinity|infinity]]. This symbol is also called a lemniscate,{{r|mind}} after the [[Lemniscate|lemniscate]] curves of a similar shape studied in [[Algebraic geometry|algebraic geometry]],{{r|beautiful}} or "lazy eight", in the terminology of [[Engineering:Livestock branding|livestock branding]].{{r|zero}}

This symbol was first used mathematically by [[Biography:John Wallis|John Wallis]] in the 17th century, although it has a longer history of other uses. In mathematics, it often refers to infinite processes (potential infinity) rather than infinite values ([[Philosophy:Actual infinity|actual infinity]]). It has other related technical meanings, such as the use of long-lasting paper in [[Engineering:Bookbinding|bookbinding]], and has been used for its symbolic value of the infinite in modern mysticism and literature. It is a common element of graphic design, for instance in corporate logos as well as in older designs such as the Métis flag.

Both the infinity symbol itself and several variations of the symbol are available in various [[Character encoding|character encoding]]s.

==History==
[[File:First known usage of the infinity symbol.jpg|thumb|First known usage of the infinity symbol, by John Wallis in 1655]]
{{multiple image|total_width=480
|image1=John Wallis by Sir Godfrey Kneller, Bt.jpg
|alt1=Portrait of John Wallis, painted in 1701 by Sir Godfrey Kneller, from the National Portrait Gallery
|caption1=[[Biography:John Wallis|John Wallis]] introduced the infinity symbol <math>\infty</math> to mathematical literature.
|image2=Infinity symbol.svg
|alt2=Eight variations of the infinity symbol
|caption2=The <math>\infty</math> symbol in several typefaces}}
The lemniscate has been a common decorative motif since ancient times; for instance it is commonly seen on [[History:Viking Age|Viking Age]] combs.{{r|viking}}

The English mathematician [[Biography:John Wallis|John Wallis]] is credited with introducing the infinity symbol with its mathematical meaning in 1655, in his ''De sectionibus conicis''.{{r|sectionibus|wallis|notations}} Wallis did not explain his choice of this symbol. It has been conjectured to be a variant form of a Roman numeral, but which Roman numeral is unclear. One theory proposes that the infinity symbol was based on the numeral for 100 million, which resembled the same symbol enclosed within a rectangular frame.{{r|beyond}} Another proposes instead that it was based on the notation CIↃ used to represent 1,000.{{r|unthinkable}} Instead of a Roman numeral, it may alternatively be derived from a variant {{nowrap|of {{char|ω}},}} the lower-case form of omega, the last letter in the Greek alphabet.{{r|unthinkable}}

Perhaps in some cases because of typographic limitations, other symbols resembling the infinity sign have been used for the same meaning.{{r|notations}} [[Biography:Leonhard Euler|Leonhard Euler]] used an open letterform more closely resembling a reflected and sideways S than a lemniscate,{{r|notations-incorrect}} and even {{nowrap|"O–O"}} has been used as a stand-in for the infinity symbol itself.{{r|notations}}

==Usage==
===Mathematics===
In mathematics, the infinity symbol is typically used to represent a potential infinity.{{r|cosmic}} For instance, in mathematical expressions with [[Summation|summation]]s and [[Limit (mathematics)|limit]]s such as

<math display=block>
\sum_{n=0}^{\infty} \frac{1}{2^n} = \lim_{x\to\infty}\frac{2^x-1}{2^{x-1}} = 2,
</math>

the infinity sign is conventionally interpreted as meaning that the variable grows [[Arbitrarily large|arbitrarily large]] towards infinity, rather than actually taking an infinite value, although other interpretations are possible.{{r|convergence}}

When quantifying [[Philosophy:Actual infinity|actual infinity]], infinite entities taken as objects per se, other notations are typically used. For example, <math>\aleph_0</math> (aleph-nought) denotes the [[Cardinal number|cardinal number]] representing the size of the set of natural numbers, and <math>\omega</math> (omega) denotes the smallest [[Ordinal number|ordinal number]] which is larger than all natural numbers.

The infinity symbol may also be used to represent a [[Point at infinity|point at infinity]], especially when there is only one such point under consideration. This usage includes, in particular, the infinite point of a [[Projective line|projective line]],{{r|algebraic}} and the point added to a [[Topological space|topological space]] to form its [[Alexandroff extension|one-point compactification]].{{r|hitchhiker}}

===Other technical uses===
[[File:Infrarotindex md 300 mm IMGP1196.jpg|thumb|upright|alt=Minolta MD 4.5/300mm IF lens|Side view of a camera lens, showing infinity symbol on the focal length indicator]]
In areas other than mathematics, the infinity symbol may take on other related meanings. For instance, it has been used in [[Engineering:Bookbinding|bookbinding]] to indicate that a book is printed on acid-free paper and will therefore be long-lasting.{{r|book}} On [[Physics:Camera|camera]]s and their [[Physics:Lens|lens]]es, the infinity symbol indicates that the lens's [[Focal length|focal length]] is [[Physics:Infinity focus|set to an infinite distance]], and is "probably one of the oldest symbols to be used on cameras".{{r|camera}}

===Symbolism and literary uses===
[[File:RWS Tarot 08 Strength.jpg|thumb|upright|alt=Strength tarot card, depicting a woman crowned by an infinity symbol, holding shut a lion's mouth|The infinity symbol appears on several cards of the Rider–Waite tarot deck.{{r|tarot}}]]

In modern mysticism, the infinity symbol has become identified with a variation of the [[Ouroboros|ouroboros]], an ancient image of a snake eating its own tail that has also come to symbolize the infinite, and the ouroboros is sometimes drawn in figure-eight form to reflect this identification—rather than in its more traditional circular form.{{r|dreams}}

In the works of Vladimir Nabokov, including ''The Gift'' and ''Pale Fire'', the figure-eight shape is used symbolically to refer to the [[Möbius strip]] and the infinite, as is the case in these books' descriptions of the shapes of bicycle tire tracks and of the outlines of half-remembered people. Nabokov's poem after which he entitled ''Pale Fire'' explicitly refers to "the miracle of the lemniscate".{{r|nabokov}} Other authors whose works use this shape with its symbolic meaning of the infinite include [[Biography:James Joyce|James Joyce]], in ''Ulysses'',{{r|sands}} and David Foster Wallace, in ''Infinite Jest''.{{r|wallace}}

===Graphic design===
The well-known shape and meaning of the infinity symbol have made it a common typographic element of graphic design. For instance, the Métis flag, used by the Canadian Métis people since the early 19th century, is based around this symbol.{{r|flags}} Different theories have been put forward for the meaning of the symbol on this flag, including the hope for an infinite future for Métis culture and its mix of European and First Nations traditions,{{r|gaudry|dumont}} but also evoking the geometric shapes of Métic dances,{{r|racette}}, Celtic knots,{{r|prefontaine}} or Plains First Nations Sign Language.{{r|barkwell}}

A [[Earth:Rainbow|rainbow]]-coloured infinity symbol is also used by the autism rights movement, as a way to symbolize the infinite variation of the people in the movement and of human cognition.{{r|autism}} The [[Chemistry:Bakelite|Bakelite]] company took up this symbol in its corporate logo to refer to the wide range of varied applications of the synthetic material they produced.{{r|bakelite}} Versions of this symbol have been used in other trademarks, corporate logos, and emblems including those of [[Company:Fujitsu|Fujitsu]],{{r|brands}} Cell Press,{{r|inspires}} and the 2022 FIFA World Cup.{{r|qatar}}

==Encoding==
The symbol is encoded in [[Unicode]] at {{unichar|221E|infinity}}{{r|compart}} and in [[Software:LaTeX|LaTeX]] as <code>\infty</code>: <math>\infty</math>.{{r|comprehensive}} An encircled version is encoded for use as a symbol for acid-free paper.
{{charmap
|221E|name1=infinity
|267E|name2=permanent paper sign

|map1=OEM-437 (Alt Code){{r|unicode-cp437}}
|map1char1=EC

|map2=[[Mac OS Roman]]{{r|unicode-mac-roman}}
|map2char1=B0

|map3=Symbol Font encoding{{r|unicode-mac-symbol}}
|map3char1=A5

|map4=Shift JIS{{r|unicode-jis}}
|map4char1=81 87

|map5=EUC-JP{{r|unicode-euc-jp}}
|map5char1=A1 E7

|map6=EUC-KR{{r|unicode-euc-kr}} / [[Unified Hangul Code|UHC]]{{r|unicode-uhc}}
|map6char1=A1 C4

|map7=[[KPS 9566|EUC-KPS-9566]]{{r|unicode-kps}}
|map7char1=A2 AC

|map8=[[Big5]]{{r|encoding}}
|map8char1=A1 DB

|IncludeGB=1

|namedref1=[[Software:LaTeX|LaTeX]]{{r|comprehensive}}
|ref1char1=\infty
|ref1char2=\acidfree

|namedref2=[[Common Locale Data Repository|CLDR]] text-to-speech name{{r|cldr}}
|ref2char1=infinity sign
|ref2char2=infinity
}}

The Unicode set of symbols also includes several variant forms of the infinity symbol that are less frequently available in fonts in the block [[Miscellaneous Mathematical Symbols-B]].{{r|unicode-misc}}
{{charmap
|29DC|name1=incomplete infinity
|29DD|name2=tie over infinity
|29DE|name3=infinity negated with vertical bar

|namedref1=[[Software:LaTeX|LaTeX]]{{r|comprehensive}}
|ref1char1=\iinfin
|ref1char2=\tieinfty
|ref1char3=\nvinfty
}}

== See also ==
* [[Aleph number]]
* [[History of mathematical notation]]
* Lazy Eight (disambiguation)

==References==
{{reflist|refs=

<ref name=algebraic>{{cite book
 | last = Perrin | first = Daniel
 | isbn = 978-1-84800-056-8
 | page = 28
 | publisher = Springer
 | title = Algebraic Geometry: An Introduction
 | url = https://books.google.com/books?id=Vn1yR9qPvlMC&pg=PA28
 | year = 2007}}</ref>

<ref name=autism>{{cite journal
 | last = Gross | first = Liza
 | date = September 2016
 | doi = 10.1371/journal.pbio.2000958
 | issue = 9
 | journal = [[Biology:PLOS Biology|PLOS Biology]]
 | page = e2000958
 | title = In search of autism's roots
 | volume = 14| pmid = 27690292
 | pmc = 5045192
 | doi-access = free
 }}</ref>

<ref name=bakelite>{{cite journal
 | last1 = Crespy | first1 = Daniel
 | last2 = Bozonnet | first2 = Marianne
 | last3 = Meier | first3 = Martin
 | date = April 2008
 | doi = 10.1002/anie.200704281
 | issue = 18
 | journal = Angewandte Chemie
 | pages = 3322–3328
 | title = 100 years of Bakelite, the material of a 1000 uses
 | volume = 47| pmid = 18318037
 | doi-access = free
 }}</ref>

<ref name=barkwell>{{cite web |last1=Barkwell |first1=Lawrence J. |title=The Metis Infinity Flag |url=http://www.metismuseum.ca/resource.php/07245 |website=Virtual Museum of Métis History and Culture |publisher=Gabriel Dumont Institute |access-date=15 July 2020}}</ref>

<ref name=beautiful>{{cite book
 | last = Erickson | first = Martin J.
 | contribution = 1.1 Lemniscate
 | contribution-url = https://books.google.com/books?id=LgeP62-ZxikC&pg=PA1
 | isbn = 978-0-88385-576-8
 | pages = 1–3
 | publisher = Mathematical Association of America
 | series = MAA Spectrum
 | title = Beautiful Mathematics
 | year = 2011}}</ref>

<ref name=beyond>{{cite book
 | isbn = 0-691-02511-8
 | mr = 1129467
 | page = 7
 | publisher = Princeton University Press | location = Princeton, New Jersey
 | title = To Infinity and Beyond: A Cultural History of the Infinite
 | url = https://books.google.com/books?id=pMY9DwAAQBAJ&pg=PA7
 | year = 1991}}</ref>

<ref name=book>{{cite book
 | last1 = Zboray | first1 = Ronald J.
 | last2 = Zboray | first2 = Mary Saracino
 | isbn = 978-0-8444-1015-9
 | page = 49
 | publisher = Center for the Book, Library of Congress
 | title = A Handbook for the Study of Book History in the United States
 | url = https://archive.org/details/handbookforstudy0000zbor/page/49
 | year = 2000}}</ref>

<ref name=brands>{{cite book
 | last1 = Rivkin | first1 = Steve
 | last2 = Sutherland | first2 = Fraser
 | isbn = 978-0-19-988340-0
 | page = 130
 | publisher = Oxford University Press
 | title = The Making of a Name: The Inside Story of the Brands We Buy
 | url = https://books.google.com/books?id=WJVcgta-HToC&pg=PA130
 | year = 2005}}</ref>

<ref name=camera>{{cite journal<!-- Although it would make more sense for this to be a conference, SAGE publishes it as a journal --> | last1 = Crist | first1 = Brian | last2 = Aurello | first2 = David N. | date = October 1990 | doi = 10.1177/154193129003400512 | issue = 5 | journal = Proceedings of the Human Factors Society Annual Meeting | pages = 489–493 | title = Development of camera symbols for consumers | volume = 34}}</ref>

<ref name=cldr>{{cite web |url=https://github.com/unicode-org/cldr/blob/master/common/annotations/en.xml |author=Unicode, Inc |title=Annotations |work=[[Common Locale Data Repository]]|via=[[GitHub]]}}</ref>

<ref name=compart>{{Cite web|url=https://www.compart.com/en/unicode/U+221E|title=Unicode Character "∞" (U+221E)|work=Unicode|publisher=Compart AG|language=en|access-date=2019-11-15}}</ref>

<ref name=comprehensive>{{cite book|contribution=Table 294: stix Infinities|page=118|title=The Comprehensive LATEX Symbol List|first=Scott|last=Pakin|date=May 5, 2021|url=https://ctan.org/pkg/comprehensive|publisher=[[CTAN]]|access-date=2022-02-19}}</ref>

<ref name=convergence>{{cite journal
 | last = Shipman | first = Barbara A.
 | date = April 2013
 | doi = 10.1080/10511970.2012.753963
 | issue = 5
 | journal = PRIMUS
 | pages = 441–458
 | title = Convergence and the Cauchy property of sequences in the setting of actual infinity
 | volume = 23| s2cid = 120023303
 }}</ref>

<ref name=cosmic>{{cite book
 | contribution = Infinity: Where God Divides by Zero
 | contribution-url = https://books.google.com/books?id=uRg6iN10JCIC&pg=PA339
 | isbn = 978-0-393-06177-2
 | pages = 339–340
 | publisher = W. W. Norton & Company
 | title = Cosmic Imagery: Key Images in the History of Science
 | year = 2008}}</ref>

<ref name=dreams>{{cite book|url=https://books.google.com/books?id=vhNNrX3bmo4C&pg=PA243|title=Dreams, Illusion, and Other Realities|last=O'Flaherty|first=Wendy Doniger|publisher=University of Chicago Press|year=1986|isbn=978-0-226-61855-5|page=243}} The book also features this image on its cover.</ref>

<ref name=dumont>{{cite web |url= http://www.metisresourcecentre.mb.ca/index.php?option=com_content&view=article&id=2&Itemid=8 |title=The Métis flag |work=Gabriel Dumont Institute(Métis Culture & Heritage Resource Centre) |archive-url=https://web.archive.org/web/20130724192737/http://metisresourcecentre.mb.ca/index.php?option=com_content&view=article&id=2&Itemid=8 |archive-date=2013-07-24}}</ref>

<ref name=encoding>{{cite web |url=https://encoding.spec.whatwg.org/big5.html |title=big5 |work=Encoding Standard |publisher=[[Organization:WHATWG|WHATWG]] |last=van Kesteren |first=Anne |}}</ref>

<ref name=flags>{{cite book|title=Native American Flags|first1=Donald T.|last1=Healy|first2=Peter J.|last2=Orenski|publisher=University of Oklahoma Press|year=2003|isbn=978-0-8061-3556-4|page=[https://archive.org/details/nativeamericanfl0000heal/page/284 284]|url=https://archive.org/details/nativeamericanfl0000heal/page/284}}</ref>

<ref name=gaudry>{{Cite journal|last=Gaudry |first=Adam |date=Spring 2018 |title= Communing with the Dead: The "New Métis," Métis Identity Appropriation, and the Displacement of Living Métis Culture |journal= American Indian Quarterly |volume=42 |issue=2 |pages=162–190 |jstor=10.5250/amerindiquar.42.2.0162 |doi=10.5250/amerindiquar.42.2.0162 |s2cid=165232342}}</ref>

<ref name=hitchhiker>{{cite book
 | edition = 3rd
 | isbn = 978-3-540-29587-7
 | pages = 56–57
 | publisher = Springer
 | title = Infinite Dimensional Analysis: A Hitchhiker's Guide
 | url = https://books.google.com/books?id=4vyXtR3vUhoC&pg=PA56
 | year = 2006}}</ref>

<ref name=inspires>{{cite journal | last = Willmes | first = Claudia Gisela | date = January 2021 | doi = 10.1016/j.molmed.2020.11.001 | issue = 1 | journal = Trends in Molecular Medicine | page = 1 | pmid = 33308981 | title = Science that inspires | volume = 27| s2cid = 229179025 | doi-access =  }}</ref>

<ref name=mind>{{cite book
 | isbn = 3-7643-3034-1
 | location = Boston, Massachusetts
 | mr = 658492
 | page = 1
 | publisher = Birkhäuser
 | title = Infinity and the Mind: The science and philosophy of the infinite
 | year = 1982}}</ref>

<ref name=nabokov>{{cite book|title=Nabokov: The Mystery of Literary Structures|first=Leona|last=Toker|publisher=Cornell University Press|year=1989|isbn=978-0-8014-2211-9|page=[https://archive.org/details/nabokovmysteryof00toke/page/159 159]|url=https://archive.org/details/nabokovmysteryof00toke|url-access=registration}}</ref>

<ref name=notations>{{Cite book|title-link=A History of Mathematical Notations|title=A History of Mathematical Notations, Volume II: Notations Mainly in Higher Mathematics|last=Cajori|first=Florian|publisher=Open Court |year=1929 |pages=44–48|contribution-url=https://archive.org/details/AHistoryOfMathematicalNotationVolII/page/n67|contribution=Signs for infinity and transfinite numbers}}</ref>

<ref name=notations-incorrect>{{harvtxt|Cajori|1929}} displays this symbol incorrectly, as a turned S without reflection. It can be seen as Euler used it on page 174 of {{cite journal|first=Leonhard|last=Euler|language=la|title=Variae observationes circa series infinitas|journal=Commentarii Academiae Scientiarum Petropolitanae|volume=9|year=1744|pages=160–188|url=http://eulerarchive.maa.org/docs/originals/E072.pdf}}</ref>

<ref name=prefontaine>{{cite journal |last1=Darren R. |first1=Préfontaine |title=Flying the Flag, Editor's note. |journal=New Breed Magazine |date=2007 |issue=Winter 2007 |page=6 |url=http://www.metismuseum.ca/resource.php/05851 |access-date=26 August 2020}}</ref>

<ref name=qatar>{{cite news|url=https://www.aljazeera.com/news/2019/09/qatar-2022-football-world-cup-logo-unveiled-190903193444377.html|publisher=Al Jazeera|title=Qatar 2022: Football World Cup logo unveiled|date=September 3, 2019}}</ref>

<ref name=racette>{{Cite book |url= http://www.metismuseum.ca/media/document.php/12153.Flags%20of%20the%20Metis.pdf |title=Flags of the Métis |last=Racette |first=Calvin |publisher=Gabriel Dumont Institute |year=1987 |isbn=0-920915-18-3}}</ref>

<ref name=sands>{{cite book | last = Bahun | first = Sanja | editor1-last = Kim | editor1-first = Rina | editor2-last = Westall | editor2-first = Claire | contribution = 'These heavy sands are language tide and wind have silted here': Tidal voicing and the poetics of home in James Joyce's Ulysses | doi = 10.1057/9781137020758_4 | pages = 57–73 | publisher = Palgrave Macmillan | title = Cross-Gendered Literary Voices: Appropriating, Resisting, Embracing | year = 2012}}</ref>

<ref name=sectionibus>{{cite book|url=https://archive.org/details/bub_gb_03M_AAAAcAAJ|title=De Sectionibus Conicis, Nova Methodo Expositis, Tractatus|last=Wallis|first=John|year=1655|pages=[https://archive.org/details/bub_gb_03M_AAAAcAAJ/page/n17 4]|language=la|chapter=Pars Prima|}}</ref>

<ref name=tarot>{{cite journal
 | last = Armson | first = Morandir
 | date = June 2011
 | issue = 1
 | journal = Literature & Aesthetics
 | pages = 196–212
 | title = The transitory tarot: an examination of tarot cards, the 21st century New Age and theosophical thought
 | url = https://openjournals.library.sydney.edu.au/index.php/LA/article/viewFile/5056/5761
 | volume = 21}} See in particular p. 203: "Reincarnation is symbolised in a number of cards within the Waite-Smith tarot deck. The primary symbols of reincarnation used are the infinity symbol or lemniscate, the wheel and the circle."</ref>

<ref name=unicode-cp437>{{cite web |url=https://unicode.org/Public/MAPPINGS/VENDORS/MICSFT/PC/CP437.TXT |title=cp437_DOSLatinUS to Unicode table |date=April 24, 1996 |last=Steele |first=Shawn |publisher=[[Organization:Unicode Consortium|Unicode Consortium]] | access-date=2022-02-19}}</ref>

<ref name=unicode-euc-jp>{{cite web |url=https://raw.githubusercontent.com/unicode-org/icu/master/icu4c/source/data/mappings/euc-jp-2007.ucm |title=EUC-JP-2007 |publisher=[[Organization:Unicode Consortium|Unicode Consortium]] |work=[[Software:International Components for Unicode|International Components for Unicode]] | access-date=2022-02-19|via=[[GitHub]]}}</ref>

<ref name=unicode-euc-kr>{{cite web |url=https://raw.githubusercontent.com/unicode-org/icu/master/icu4c/source/data/mappings/ibm-970_P110_P110-2006_U2.ucm |title=IBM-970 |publisher=[[Organization:Unicode Consortium|Unicode Consortium]] |work=[[Software:International Components for Unicode|International Components for Unicode]]|date=May 9, 2007 | access-date=2022-02-19|via=[[GitHub]]}}</ref>

<ref name=unicode-jis>{{cite web |url=https://www.unicode.org/Public/MAPPINGS/OBSOLETE/EASTASIA/JIS/SHIFTJIS.TXT |title=Shift-JIS to Unicode |publisher=[[Organization:Unicode Consortium|Unicode Consortium]] |date=December 2, 2015 | access-date=2022-02-19}}</ref>

<ref name=unicode-kps>{{cite web |url=https://unicode.org/Public/MAPPINGS/VENDORS/MISC/KPS9566.TXT |title=KPS 9566-2003 to Unicode |date=April 27, 2011 |publisher=[[Organization:Unicode Consortium|Unicode Consortium]] | access-date=2022-02-19}}</ref>

<ref name=unicode-mac-roman>{{cite web |url=http://unicode.org/Public/MAPPINGS/VENDORS/APPLE/ROMAN.TXT |title=Map (external version) from Mac OS Roman character set to Unicode 2.1 and later |date=April 5, 2005 |publisher=[[Company:Apple Inc.|Apple Inc.]] |via=[[Organization:Unicode Consortium|Unicode Consortium]]| access-date=2022-02-19}}</ref>

<ref name=unicode-mac-symbol>{{cite web |url=http://unicode.org/Public/MAPPINGS/VENDORS/APPLE/SYMBOL.TXT |title=Map (external version) from Mac OS Symbol character set to Unicode 4.0 and later|date=April 5, 2005 |publisher=[[Company:Apple Inc.|Apple Inc.]] |via=[[Organization:Unicode Consortium|Unicode Consortium]]| access-date=2022-02-19}}</ref>

<ref name=unicode-misc>{{cite web|url=https://www.unicode.org/charts/PDF/U2980.pdf|title=Miscellaneous Mathematical Symbols-B|publisher=[[Organization:Unicode Consortium|Unicode Consortium]]|archive-url=https://web.archive.org/web/20181112231107/https://www.unicode.org/charts/PDF/U2980.pdf|archive-date=2018-11-12|url-status=live| access-date=2022-02-19}}</ref>

<ref name=unicode-uhc>{{cite web |url=https://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WINDOWS/CP949.TXT |title=cp949 to Unicode table |last=Steele |first=Shawn |publisher=[[Organization:Unicode Consortium|Unicode Consortium]] |date=January 7, 2000 | access-date=2022-02-19}}</ref>

<ref name=unthinkable>{{cite book
 | contribution = Chapter 6: Labelling the infinite
 | isbn = 978-1-84119-650-3
 | publisher = Constable & Robinson Ltd
 | title = A Brief History of Infinity: The Quest to Think the Unthinkable
 | year = 2003}}</ref>

<ref name=viking>{{cite journal
 | last = van Riel | first = Sjoerd
 | journal = Lund Archaeological Review
 | pages = 163–178
 | title = Viking Age Combs: Local Products or Objects of Trade?
 | url = https://journals.lub.lu.se/lar/article/view/21656
 | volume = 23
 | year = 2017}} See p. 172: "Within this type the lemniscate (∞) is a commonly used motif."</ref>

<ref name=wallace>{{cite book | last = Natalini | first = Roberto | editor1-last = Boswell | editor1-first = Marshall | editor2-last = Burn | editor2-first = Stephen J. | contribution = David Foster Wallace and the mathematics of infinity | doi = 10.1057/9781137078346_3 | pages = 43–57 | publisher = Palgrave Macmillan | series = American Literature Readings in the 21st Century | title = A Companion to David Foster Wallace Studies | year = 2013}}</ref>

<ref name=wallis>{{cite book
 | last = Scott | first = Joseph Frederick
 | edition = 2nd
 | isbn = 0-8284-0314-7
 | page = 24
 | publisher = American Mathematical Society
 | title = The mathematical work of John Wallis, D.D., F.R.S., (1616-1703)
 | url = https://books.google.com/books?id=XX9PKytw8g8C&pg=PA24
 | year = 1981}}</ref>

<ref name=zero>{{cite book|title=Zero to Lazy Eight: The Romance of Numbers|first1=Alexander|last1=Humez|first2= Nicholas D.|last2=Humez|first3= Joseph|last3= Maguire|publisher	=Simon and Schuster|year=1993|isbn= 978-0-671-74281-2|page=18|url=https://books.google.com/books?id=X429EAr8g4kC&pg=PA18}}</ref>

}}

{{Infinity}}
[[Category:Mathematical symbols]]
[[Category:Infinity]]

{{Sourceattribution|Infinity symbol}}