Gaston Maurice Julia (3 February 1893 – 19 March 1978) was a French Algerian mathematician who devised the formula for the
Julia set
In the context of complex dynamics, a branch of mathematics, the Julia set and the Fatou set are two complementary sets (Julia "laces" and Fatou "dusts") defined from a function. Informally, the Fatou set of the function consists of values wit ...
. His works were popularized by French mathematician
Benoit Mandelbrot
Benoit B. Mandelbrot (20 November 1924 – 14 October 2010) was a Polish-born French-American mathematician and polymath with broad interests in the practical sciences, especially regarding what he labeled as "the art of roughness" of phy ...
; the Julia and Mandelbrot
fractal
In mathematics, a fractal is a geometric shape containing detailed structure at arbitrarily small scales, usually having a fractal dimension strictly exceeding the topological dimension. Many fractals appear similar at various scales, as illu ...
s are closely related. He founded, independently with
Pierre Fatou
Pierre Joseph Louis Fatou (28 February 1878 – 9 August 1929) was a French mathematician and astronomer. He is known for major contributions to several branches of analysis. The Fatou lemma and the Fatou set are named after him.
Biography
P ...
, the modern theory of
holomorphic dynamics
Complex dynamics is the study of dynamical systems defined by iteration of functions on complex number spaces. Complex analytic dynamics is the study of the dynamics of specifically analytic functions.
Techniques
*General
**Montel's theorem
**Po ...
.
Military service
Julia was born in the
Algeria
)
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, map_caption =
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, capital = Algiers
, coordinates =
, largest_city = capital
, relig ...
n town of
Sidi Bel Abbes
''Sidi'' or ''Sayidi'', also Sayyidi and Sayeedi, ( ar, سيدي, Sayyīdī, Sīdī (dialectal) "milord") is an Arabic masculine title of respect. ''Sidi'' is used often to mean "saint" or "my master" in Maghrebi Arabic and Egyptian Arabic. Wi ...
, at the time governed by the
French. During his youth, he had an interest in mathematics and music. His studies were interrupted at the age of 21, when France became involved in
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
and Julia was conscripted to serve with the army. During an attack he suffered a severe injury, losing his nose. His many operations to remedy the situation were all unsuccessful, and for the rest of his life he resigned himself to wearing a leather strap around the area where his nose had been.
Career in mathematics
Julia gained attention for his mathematical work at the age of 25, in 1918, when his 199-page ''Mémoire sur l'itération des fonctions rationnelles'' ("Memoir on the Iteration of Rational Functions") was featured in the ''
Journal de Mathématiques Pures et Appliquées
The ''Journal de Mathématiques Pures et Appliquées'' () is a French monthly scientific journal of mathematics, founded in 1836 by Joseph Liouville (editor: 1836–1874). The journal was originally published by Charles Louis Étienne Bachelier. A ...
''. This article gained immense popularity among mathematicians and earned him the ''Grand Prix des Sciences Mathématiques'' of the
French Academy of Sciences
The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV of France, Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific me ...
in 1918. But after this brief moment of fame, his works were mostly forgotten until the day
Benoit Mandelbrot
Benoit B. Mandelbrot (20 November 1924 – 14 October 2010) was a Polish-born French-American mathematician and polymath with broad interests in the practical sciences, especially regarding what he labeled as "the art of roughness" of phy ...
mentioned them in his works on
fractal
In mathematics, a fractal is a geometric shape containing detailed structure at arbitrarily small scales, usually having a fractal dimension strictly exceeding the topological dimension. Many fractals appear similar at various scales, as illu ...
s.
On 19 March 1978, Julia died in Paris at the age of 85.
Julia was also father to
Marc Julia
Marc Julia (23 October 1922 – 29 June 2010) was a French chemist and the winner of the 1990 CNRS Gold Medal in chemistry. He discovered the Julia olefination reaction in 1973.
Biography
Julia was born in 1922 in Paris as son of the renowned m ...
, the French organic chemist who invented the
Julia olefination
The Julia olefination (also known as the Julia–Lythgoe olefination) is the chemical reaction used in organic chemistry of phenyl sulfones (1) with aldehydes (or ketones) to give alkenes (olefins)(3) after alcohol functionalization and reductive ...
.
World War Two and collaboration
Julia had
collaborated
Collaboration (from Latin ''com-'' "with" + ''laborare'' "to labor", "to work") is the process of two or more people, entities or organizations working together to complete a task or achieve a goal. Collaboration is similar to cooperation. Most ...
with the
Nazi Germany
Nazi Germany (lit. "National Socialist State"), ' (lit. "Nazi State") for short; also ' (lit. "National Socialist Germany") (officially known as the German Reich from 1933 until 1943, and the Greater German Reich from 1943 to 1945) was ...
during the
occupation of France
The Military Administration in France (german: Militärverwaltung in Frankreich; french: Occupation de la France par l'Allemagne) was an interim occupation authority established by Nazi Germany during World War II to administer the occupied zo ...
. He searched and found French mathematicians to collaborate with the
Zentralblatt für Mathematik
zbMATH Open, formerly Zentralblatt MATH, is a major reviewing service providing reviews and abstracts for articles in pure and applied mathematics, produced by the Berlin office of FIZ Karlsruhe – Leibniz Institute for Information Infrastructur ...
, and was suspended for a few weeks after the
liberation of France
The liberation of France in the Second World War was accomplished through diplomacy, politics and the combined military efforts of the Allied Powers of World War II, Allied Powers, Free French forces in London and Africa, as well as the French R ...
. But according to
Michèle Audin
Michèle Audin (Algiers, 3 January, 1954) is a French mathematician, writer, and a former professor. She has worked as a professor at the University of Geneva, the University of Paris-Saclay and most recently at the University of Strasbourg, where ...
:
Books
*''Oeuvres'', 6 vols., Paris, Gauthier-Villars 1968-1970 (eds.
Jacques Dixmier
Jacques Dixmier (born 24 May 1924) is a French mathematician. He worked on operator algebras, especially C*-algebras, and wrote several of the standard reference books on them, and introduced the Dixmier trace and the Dixmier mapping.
Biogra ...
,
Michel Hervé, with foreword by Julia)
*''Leçons sur les Fonctions Uniformes à Point Singulier Essentiel Isolé'', Gauthier-Villars 1924 (rédigées par
P. Flamant)
*''Eléments de géométrie infinitésimale'', Gauthier-Villars 1927
*''Cours de Cinématique'', Gauthier-Villars 1928, 2nd edition 1936
*''Exercices d'Analyse'', 4 vols., Gauthier-Villars, 1928 - 1938, 2nd edition 1944, 1950
*''Principes Géométriques d'Analyse'', 2 vols., Gauthier-Villars, 1930, 1932
*''Essai sur le Développement de la Théorie des Fonctions de Variables Complexes'', Gauthier-Villars 1933
*''Introduction Mathématique aux Theories Quantiques'', 2 vols., Gauthier-Villars 1936, 1938,
2nd edition 1949, 1955
*''Eléments d'algèbre'', Gauthier-Villars 1959
*''Cours de Géométrie'', Gauthier-Villars 1941
*''Cours de géométrie infinitésimale'', Gauthier-Villars, 2nd edition 1953
*''Exercices de géométrie'', 2 vols., Gauthier-Villars 1944, 1952
*''Leçons sur la représentation conforme des aires simplement connexes'', Gauthier-Villars 1931, 2nd edition 1950
*''Leçons sur la représentation conforme des aires multiplement connexes'', Gauthier-Villars 1934
*''Traité de Théorie de Fonctions'', Gauthier-Villars 1953
*''Leçons sur les fonctions monogènes uniformes d'une variable complexe'', Gauthier-Villars 1917
*''Étude sur les formes binaires non quadratiques à indéterminées réelles ou complexes, ou à indéterminées conjuguées'', Gauthier-Villars 1917
See also
*
Mandelbrot set
The Mandelbrot set () is the set of complex numbers c for which the function f_c(z)=z^2+c does not diverge to infinity when iterated from z=0, i.e., for which the sequence f_c(0), f_c(f_c(0)), etc., remains bounded in absolute value.
This ...
References
External links
*
*
* ''Memoir on iteration of rational functions'', English translation in parts
1/72/7
3/74/75/76/77/7
Downloadable articles at Numdam
Diplomica GmbH Hamburg (2008)
* Daniel Alexander, Felice Iavernaro, Alessandro Rosa
''Early days in complex dynamics: a history of complex dynamics in one variable during 1906-1942''
History of Mathematics 38, American Mathematical Society 2012
{{DEFAULTSORT:Julia, Gaston
1893 births
1978 deaths
École Normale Supérieure alumni
20th-century French mathematicians
University of Paris alumni
University of Paris faculty
Members of the French Academy of Sciences
People from Sidi Bel Abbès
French military personnel of World War I
Pieds-Noirs
Migrants from French Algeria to France