StoriedNo. 058Mathematics · Number theory & elasticity
Memorial medallion · B. Chégaray, engr. J. Poinsot · 1900
Sophie Germain
1776 — 1831
She learned mathematics by candlelight, signed it with a man's name, and still beat Paris to the answer.
In 1789, as revolution filled the streets around her father's house in Paris, a thirteen-year-old girl hid in the family library and read how Archimedes was killed by a Roman soldier, too absorbed in a geometry problem to look up. Anything that could hold a man that completely, Sophie Germain decided, was worth her life. Her parents disagreed; by family tradition they took away her candles and her fire at night, and found her in the morning asleep over her slate, the ink frozen in its well.
No school would teach her. So she taught herself Latin and Greek to read Newton and Euler, borrowed the lecture notes of a college that barred women, and sent her work to the greatest mathematicians in Europe under a borrowed man's name, Monsieur Le Blanc. They answered as equals. By the time they learned who she was, she had already earned it.
A life in Paris
The lifeline
1776
Born 1 April in Paris, daughter of a prosperous silk merchant
1789
At 13, the Bastille falls and she turns to her father's books
c.1795
As "M. Le Blanc", sends a paper to Lagrange, who calls on her in person
1804
Begins writing to Gauss on number theory, still in disguise
1816
On her third try, wins the Academy of Sciences' prize on elasticity
1831
Dies of breast cancer on 27 June, aged 55
By the numbers
The measure of her
3
Entries for the Academy's elasticity prize: 1811, 1813, 1816. Only the third won
<100
Every prime below 100 was covered by her attack on Fermat's Last Theorem
72
Scientists' names engraved on the Eiffel Tower, for a structure that rests on elasticity. Hers is not one
1972
The year the École Polytechnique, whose notes she borrowed, first admitted women
What she proved
The work
Sand gathers on the still lines of a vibrating plate. Ernst Chladni showed these figures in Paris in 1808. No one could explain them. She wrote the first theory that tried.
c.1795
A paper to Lagrange, written from the École Polytechnique's lecture notes and signed with the name of a former student. Lagrange asked to meet its author.
1804–08
Letters to Gauss, who praised her proofs in number theory. In 1806, with French troops in Brunswick, she asked a general to see to his safety. That is how he learned "Le Blanc" was a woman.
1816
The prix extraordinaire of the Institut de France for a theory of vibrating elastic surfaces: the first woman to win a prize from the Academy of Sciences. She stayed away from the ceremony.
1821
Recherches sur la théorie des surfaces élastiques, printed at her own expense. Her approach fed into the elasticity theory engineers still use.
1825
Sophie Germain's theorem, the most important general result on Fermat's Last Theorem before Kummer's work of the 1840s, credited to her in a footnote by Legendre. Primes p with 2p+1 also prime still bear her name.
Hidden, then honoured
Recognition
In her lifetime
No university, school or academy would admit her
Wrote to Lagrange and Gauss under a man's name
Poisson and others faulted the rigour of her prize paper
Gauss urged Göttingen to give her an honorary degree; she died before it was granted
Her death certificate is said to call her a rentière, a woman of property, not a mathematician
Today
"Sophie Germain primes" are a standard object in number theory and cryptography
The Académie des sciences has awarded the Prix Sophie Germain since 2003
A Paris lycée and a street in the 14th arrondissement carry her name
A plaque marks the house on rue de Savoie where she died
The place that made her
Revolutionary Paris
She was born on the rue Saint-Denis, and her father, Ambroise-François Germain, sat for the Third Estate in the assembly that remade France. The revolution kept her indoors and gave her the library. It also created the École Polytechnique in 1794, a school she could never enter but whose notes still reached her.
13
Her age when the Bastille fell, 14 July 1789
1794
The École Polytechnique opens. Men only
Div. 16
Her grave at Père-Lachaise cemetery, Paris
"When a person of the sex which, according to our customs and prejudices, must encounter infinitely more difficulties than men … succeeds nevertheless in surmounting these obstacles, then without doubt she must have the noblest courage, quite extraordinary talents and superior genius."
— Carl Friedrich Gauss, letter to Sophie Germain, 30 April 1807
