André-Marie Ampère, the self-taught 'Newton of electricity'
Ampère never attended school. His father, a devotee of Rousseau, let him educate himself in the family library, where he began advanced mathematics at 12. In 1820 he heard of a compass needle twitching near a live wire, and within weeks was building the science he named electrodynamics.
Born in Lyon on 20 January 1775 to a prosperous merchant, Ampère grew up on the family estate at Poleymieux-au-Mont-d'Or, now home to a museum of his life and of electricity. Diderot and d'Alembert's Encyclopédie and Buffon's natural history served as his teachers, and resumed Latin lessons opened up Euler and Bernoulli. He later claimed he knew as much mathematics and science at eighteen as he ever would. The Revolution then struck the family hard: his father, a local judge who resisted the Jacobins, was guillotined in November 1793.
Ampère married Julie Carron in 1799 and took his first steady job teaching mathematics. Posted to Bourg-en-Bresse in 1802, he wrote a treatise on the mathematics of gambling, but his wife died in July 1803 and he moved to Paris. Despite having no formal qualifications, he became professor of mathematics at the École Polytechnique in 1809 and in 1824 won the chair of experimental physics at the Collège de France. A devout Catholic, he also took the young Frédéric Ozanam, later a founder of the Society of Saint Vincent de Paul, into his household.
The turning point came in September 1820, when François Arago showed the Academy of Sciences Hans Christian Ørsted's discovery that an electric current deflects a magnetic needle. Ampère quickly demonstrated that two parallel wires attract when their currents run the same way and repel when they run opposite ways. He expressed the force mathematically in what became Ampère's law, and proposed an electrodynamic molecule, a forerunner of the electron, underlying both electricity and magnetism. Einstein and Wander de Haas confirmed that hypothesis in 1915. His 1826 memoir on electrodynamic phenomena became the field's founding text, and he also coined the words solenoid and, via French, kinematic.
His last years were spent in poverty and illness, wrestling with a theory of knowledge after reading Kant; contemporaries found him baffling. He died of a lung infection in Marseille in 1836. James Clerk Maxwell called him the Newton of electricity, and an 1881 international convention made the ampere a standard unit of current. His name is among the 72 engraved on the Eiffel Tower.
Source: André-Marie Ampère
