View source for Mary Cartwright

{{Short description|British mathematician (1900–1998)}}
{{EngvarB|date=July 2017}}
{{Use dmy dates|date=April 2023}}
{{Infobox scientist
| honorific_prefix  = [[Dame]]
| honorific_suffix  = {{Post-nominals|country=GBR|size=100%|DBE|FRS|FRSE}}
| image             = Mary cartwright.jpg
| caption           = Cartwright in 1950
| birth_date        = {{birth date|df=yes|1900|12|17}}
| birth_place       = [[Aynho]], England
| death_date        = {{death date and age|df=yes|1998|4|3|1900|12|17}}
| death_place       = [[Cambridge]], England
| alma_mater        = [[St Hugh's College, Oxford]]
| doctoral_advisor  = [[G. H. Hardy]]
| doctoral_students = {{plainlist|
*[[Walter Hayman]]
*[[Elizabeth McHarg]]
}}
| notable_students  = [[Sheila Scott Macintyre]]
| known_for         = *[[Cartwright's Theorem]]
*Research about the [[Butterfly effect]]
| prizes            = {{plainlist|
*[[De Morgan Medal]] (1968)
*[[Sylvester Medal]] (1964)
}}
}}

'''Dame Mary Lucy Cartwright''' {{Post-nominals|country=GBR|DBE|FRS|FRSE}} (17 December 1900&nbsp;– 3 April 1998)<ref>{{Cite news|title=Obituary: Mary Cartwright|journal=[[The Times]]|year=1998|url=https://mathshistory.st-andrews.ac.uk/Obituaries/Cartwright/}}</ref> was a British mathematician. She was one of the pioneers of what would later become known as [[chaos theory]].<ref>[[Freeman Dyson|Freeman J. Dyson]], [https://books.google.com/books?id=CQeKFG01s-oC&pg=PA169 ''Mary Lucy Cartwright (1900–1998): Chaos theory''], pp. 169–177, in ''Out of the Shadows: Contributions of Twentieth-Century Women to Physics'', edited by [[Nina Byers]] and Gary Williams, 498 p. (Cambridge University Press, 2006); {{isbn|0-521-82197-5}}</ref> Along with [[J. E. Littlewood]], Cartwright saw many solutions to a problem which would later be seen as an example of the [[butterfly effect]].

==Early life and education==
[[File:Young Skewes Schieldrop Tricomi Cartwright Zurich1932.tif|thumb|Mary Cartwright (far right) at the International Congress of Mathematicians in 1932.]]
Mary Cartwright was born on 17 December 1900, in [[Aynho]], Northamptonshire, where her father William Digby was [[vicar]]. Through her grandmother Jane Holbech, she descended from poet [[John Donne]] and [[William Mompesson]], Vicar of Eyam.<ref name="mathgene">{{MathGenealogy |id=18533}}</ref><ref name="mactutor">{{MacTutor Biography|id=Cartwright}}</ref> She had four siblings, two older and two younger: John (born 1896), Nigel (born 1898), Jane (born 1905), and William (born 1907).<ref name="mcs-andrews" /> Her early education was at Leamington High School (1912–1915), and then at Gravely Manor School in [[Boscombe]] (1915–1916) before completion in [[Godolphin School]] in Salisbury (1916–1919).<ref name="royalsoced1">{{cite web|url=https://www.royalsoced.org.uk/cms/files/fellows/biographical_index/fells_indexp1.pdf|title=Former Fellows of the Royal Society of Edinburgh 1783–2002|publisher=Royalsoced.org.uk|access-date=20 December 2015}}</ref>

Cartwright studied mathematics at [[St Hugh's College, Oxford]], graduating in 1923 with a first class degree. She was the first woman to attain the final degree lectures and to obtain a first. She briefly taught at [[Alice Ottley School]] in [[Worcester, England|Worcester]] and [[Wycombe Abbey School]] in Buckinghamshire before returning to Oxford in 1928 to read for her [[Doctor of Philosophy|D.Phil]]. Cartwright was supervised by [[G. H. Hardy]] in her doctoral studies. During the academic year 1928–9 Hardy was at [[Princeton University|Princeton]], so it was [[E. C. Titchmarsh]] who took over the duties as a supervisor. Her thesis "The Zeros of Integral Functions of Special Types" was examined by [[J. E. Littlewood]], whom she met for the first time as an external examiner in her oral examination for that 1930 D.Phil.<ref name="mactutor" />

In 1930, Cartwright was awarded a [[Yarrow Research Fellowship]] and went to [[Girton College]], [[University of Cambridge|Cambridge]] to continue working on the topic of her doctoral thesis. Attending Littlewood's lectures, she solved one of the open problems which he posed. Her mathematical theorem, now known as [[Cartwright's Theorem]], gives an estimate for the maximum modulus of an [[analytic function]] that takes the same value no more than ''p'' times in the [[unit disc]]. To prove the theorem she used a new approach, applying a technique introduced by [[Lars Ahlfors]] for [[conformal geometry|conformal mappings]].<ref>{{cite web|url=https://prezi.com/2pdjgbqmvfu-/mary-lucy-carwright/|title=Mary Lucy Cartwright|first=Jack|last=DeFuria|publisher=Prezi|date=22 October 2014|access-date=8 March 2017}}</ref><ref name="Cartwright obituary ams.org">{{Cite journal|last1=McMurran|first1=Shawnee|last2=Tattersall|first2=James|date=February 1999|title=Mary Cartwright
|url=https://www.ams.org/journals/notices/199902/mem-cartwright.pdf|journal=Notices of the AMS|volume=46}}</ref> While at Cambridge Cartwright attended the mathematical lectures of [[Ludwig Wittgenstein]].<ref>{{cite book |editor1-last=McGuinness |editor1-first=Brian |title=Wittgenstein in Cambridge: Letters and Documents 1911 - 1951 |date=2012 |publisher=John WIley & Sons |page=207}}</ref>

== Career ==
Throughout her career, Cartwright wrote over ninety articles on several different mathematical concepts. Her contributions extended to topics such as the Dirichlet series, Abel summation, directions of Borel spreads, analytic functions regular on the unit disk, the zeros of integral functions, maximum and minimum moduli, and functions of finite order in an angle.<ref name="Cartwright obituary ams.org"/> 
In 1936, Cartwright became director of studies in mathematics at Girton College. In 1938, she began work on a new project which had a major impact on the direction of her research. The Radio Research Board of the [[Department of Scientific and Industrial Research (United Kingdom)|Department of Scientific and Industrial Research]] produced a memorandum regarding [[Van der Pol oscillator|certain differential equations]] which came out of modelling radio and radar work.<ref name="bbc.co.uk">{{Cite news|title=A Point of View: Mary, queen of maths|date=8 March 2013|journal=BBC News Magazine|url=https://www.bbc.co.uk/news/magazine-21713163}}</ref> They asked the [[London Mathematical Society]] if they could help find a mathematician who could work on these problems and she became interested. The dynamics lying behind the problems were unfamiliar to Cartwright, so she approached Littlewood for help with this aspect. They began to collaborate studying the equations, in particular the [[Van der Pol oscillator]], which greatly surprised the two:{{blockquote|For something to do we went on and on at the thing with no earthly prospect of "results"; suddenly the whole vista of the dramatic fine structure of solutions stared us in the face.<ref name="Littlewood Miscellany Bollobás ">{{cite book | last=Littlewood | first=John Edensor |  editor-last=Bollobás | editor-first=Béla | title=Littlewood's Miscellany | publisher=Cambridge University Press | publication-place=Cambridge New York Port Chester [etc.] | date=1986-10-30 | isbn=0-521-33702-X | page=13}}</ref>}}
The fine structure described here is today seen to be a typical instance of the [[butterfly effect]]. The collaboration led to important results which have greatly influenced the direction that the modern theory of [[dynamical systems]] has taken.<ref name="obituary">{{cite web|url=http://cwp.library.ucla.edu/articles/ebcart11.html|title=Mistress of Girton whose mathematical work formed the basis of chaos theory|work=Obituaries Electronic Telegraph|date=11 April 1998|access-date=8 March 2017}}</ref><ref name="hayman">{{cite journal|url=http://rsbm.royalsocietypublishing.org/content/46/19|author=Walter Hayman|author-link=Walter Hayman|title=Dame Mary (Lucy) Cartwright, D.B.E. 17 December 1900 – 3 April 1998|journal=Biographical Memoirs of Fellows of the Royal Society|volume=46|pages=19–35|date=1 November 2000|access-date=8 March 2017|doi=10.1098/rsbm.1999.0070|doi-access=free}}</ref> Although the duo did not supply the answer in time, they succeeded in directing the engineers' attention away from faulty equipment towards practical ways of compensating for the electrical "noise"—or erratic fluctuations—being produced.<ref name="bbc.co.uk"/>

In 1945, Cartwright simplified [[Charles Hermite|Hermite]]'s [[Proof that π is irrational#Cartwright.27s proof|elementary proof of the irrationality of {{pi}}]]. She set her version of the proof as a [[Mathematical Tripos|Tripos]] question, later published in an appendix to Sir [[Harold Jeffreys]]' book ''Scientific Inference''.<ref name="Jeffreys Inference 1973 ">{{cite book | last=Jeffreys | first=Harold | title=Scientific Inference | publisher=Cambridge University Press | publication-place=Cambridge | date=1973-12-13 | isbn=0-521-08446-6 | page=268 | edition=3rd }}</ref> In 1947, she was elected to be a [[Fellow of the Royal Society]];<ref name="frs">{{Cite journal|last1=Hayman|first1=Walter K.|doi=10.1098/rsbm.1999.0070|title=Dame Mary (Lucy) Cartwright, D.B.E. 17 December 1900 – 3 April 1998: Elected F.R.S. 1947|journal=[[Biographical Memoirs of Fellows of the Royal Society]]|volume=46|page=19|year=2000|doi-access=free}}</ref> although she was not the first woman to be elected to that Society, she was the first female mathematician.<ref name="obituary" /><ref name="hayman" />

Cartwright was appointed Mistress of Girton in 1948 and a Reader in the Theory of Functions in Cambridge in 1959 until 1968.<ref name="mactutor" /> From 1957 to 1960, she was president of the Cambridge Association of University Women.<ref name=":0">{{Cite ODNB|title=Cartwright, Dame Mary Lucy (1900–1998), mathematician {{!}} Oxford Dictionary of National Biography|language=en|doi=10.1093/ref:odnb/69671|year = 2004}}</ref> After retiring from Girton, she was a visiting professor at [[Brown University]] from 1968 to 1969 and at [[Claremont Graduate University|Claremont Graduate School]] from 1969 to 1970.<ref name=":0" /> Cartwright died in Cambridge, on 3 April 1998 at the age of 97.<ref name="Cartwright obituary ams.org"/>

==Recognition==
Cartwright was the first woman:
*to serve on the Council of the [[Royal Society]]<ref name="frs"/>
*to be President of the [[Mathematical Association]] (in 1951)<ref>{{citation
 | last = Williams | first = Mrs. E. M.| author-link = Elizabeth Williams (educationist)
 | date = October 1966
 | doi = 10.2307/3614669
 | issue = 373
 | pages = 243–254| journal = The Mathematical Gazette
 | title = Presidential Address: The Changing Role of Mathematics in Education
 | volume = 50| jstor = 3614669| s2cid = 186846165}}</ref>
*to be President of the [[London Mathematical Society]] (in 1961–62)<ref name="mcs-andrews" />
*to receive the [[Sylvester Medal]] (in 1964)<ref name="mcs-andrews">{{cite web |last1=O'Connor |first1=J. J. |last2=Robertson |first2=E. F. |title=Dame Mary Lucy Cartwright |url=http://www-history.mcs.st-andrews.ac.uk/Biographies/Cartwright.html |publisher=School of Mathematics and Statistics, University of St Andrews |access-date=3 April 2019}}</ref>
* to receive the [[De Morgan Medal]], the highest award of the [[London Mathematical Society]] (in 1968)<ref name="auto">{{Cite web|url=https://mathwomen.agnesscott.org/women/prizes.htm#demorgan|title=Prizes, Awards, and Honors for Women Mathematicians|website=mathwomen.agnesscott.org}}</ref>

In 1968, Cartwright became the first woman to receive the [[De Morgan Medal]], the highest award of the [[London Mathematical Society]],<ref name="auto"/><ref>[http://www.lms.ac.uk/content/list-lms-prize-winners List of LMS prize winners], LMS website, accessed July 2011</ref> and was elected an Honorary Fellow of The Royal Society of Edinburgh (HonFRSE).<ref>{{Cite web |url=https://www.rse.org.uk/fellow/mary-lucy-cartwright/ |title=Dame Mary Lucy Cartwright Hon FRSE |date=28 October 2016 |website=The Royal Society of Edinburgh |access-date=23 March 2019 }}</ref> In 1969, she received the distinction of being honoured by the Queen, becoming Dame Mary Cartwright, [[Dame Commander of the Order of the British Empire]].

==Death==
Cartwright died in Midfield Lodge Nursing Home in [[Cambridge]] in 1998.<ref name="royalsoced1"/>

==Publications==
* {{cite journal | last1=Cartwright | first1=M. L. | last2=Littlewood | first2=J. E. |author-link2=J. E. Littlewood| title=On Non-Linear Differential Equations of the Second Order: I. the Equation <math> \ddot y - k(1-y^2) \dot y + y = b\lambda k \cos(\lambda t+\alpha),</math> <math>k</math> Large | journal=Journal of the London Mathematical Society | publisher=Wiley | volume=s1-20 | issue=3 | year=1945 | issn=0024-6107 | doi=10.1112/jlms/s1-20.3.180 | pages=180–189}}
* {{cite book | last=Cartwright | first=M. L. | title=Integral functions | publisher=University Press, Cambridge | series=Cambridge Tracts in Mathematics and Mathematical Physics | number=44 | date=1962 | oclc=8697638 }}
* {{cite journal | last=Cartwright | first=M. L. | title=From Non-Linear Oscillations to Topological Dynamics | journal=Journal of the London Mathematical Society | publisher=Wiley | volume=s1-39 | issue=1 | year=1964 | issn=0024-6107 | doi=10.1112/jlms/s1-39.1.193 | pages=193–201}}

==References==
{{Reflist}}

==External links==
* [http://www.agnesscott.edu/lriddle/women/cartwght.htm Dame Mary Lucy Cartwright] at Biographies of Women Mathematicians, [[Agnes Scott College]]

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{{s-aca}}
{{succession box |
  before=[[Kathleen Teresa Blake Butler]]|
  title= [[List of Mistresses of Girton College, Cambridge|Mistress of]] [[Girton College, Cambridge]]|
  years=1949–1968|
  after=[[M. C. Bradbrook|Muriel Clara Bradbrook]]
}}
{{end}}
{{Chaos theory}}
{{De Morgan Medallists}}
{{Authority control}}

{{DEFAULTSORT:Cartwright, Mary}}
[[Category:1900 births]]
[[Category:1998 deaths]]
[[Category:Alumni of St Hugh's College, Oxford]]
[[Category:20th-century British mathematicians]]
[[Category:Dames Commander of the Order of the British Empire]]
[[Category:Female fellows of the Royal Society]]
[[Category:Fellows of Girton College, Cambridge]]
[[Category:Mistresses of Girton College, Cambridge]]
[[Category:People from Aynho]]
[[Category:People educated at Godolphin School]]
[[Category:Fellows of the Royal Society]]
[[Category:20th-century British women scientists]]
[[Category:20th-century British women mathematicians]]