Leonhard Euler gave mathematics much of the notation it still writes today
Every time a student writes pi for a circle, sigma for a sum or e for natural growth, they are borrowing notation Leonhard Euler made standard. He produced 866 publications, founded graph theory by puzzling over seven bridges in Königsberg, and was hailed by Laplace as the master of us all.
Euler was born in Basel on 15 April 1707, the eldest of four children of a Reformed pastor, and grew up in nearby Riehen. His father, who had studied under Jacob Bernoulli, taught him mathematics early. He entered the University of Basel at 13, where Jacob's brother Johann Bernoulli refused him private lessons but offered something better: read the hardest books alone, then bring the sticking points every Saturday afternoon. With Bernoulli's backing, he persuaded his father to let him become a mathematician rather than a minister.
An early essay on sound failed to win him a Basel post, and he took second place in a Paris Academy contest on placing ships' masts; over the years he would enter that competition 15 times and win 12. Johann's sons Daniel and Nicolaus had gone to the new Russian academy in Saint Petersburg, founded to close Russia's scientific gap with the West, and Daniel secured Euler a place. He arrived in May 1727, lodged with Daniel, also served as a medic in the Russian Navy, and succeeded Daniel as head of mathematics when his friend left.
Political turmoil in Russia, and an offer matching his salary from Frederick the Great, drew him to Berlin in 1741, citing a milder climate for his eyesight. He stayed 25 years, writing influential texts on analysis and differential calculus, and more than 200 letters to Frederick's niece that became his most widely read work, admired for explaining science to non-specialists.
The breadth is staggering. He defined e, the base of natural logarithms; solved the Basel problem; noticed that for any polyhedron without holes, vertices plus faces minus edges always equals 2; recast Newton's mechanics for rigid bodies; wrote equations for frictionless fluids; and studied ships, lenses and the bending of beams. Gauss judged his works the best school in mathematics. Euler died on 18 September 1783.
Source: Leonhard Euler
