Leonhard Euler

Born in Switzerland in 1707, Euler spent most of his working life shuttling between Saint Petersburg and Berlin, where he turned nearly every corner of 18th-century science he touched. He founded graph theory with the Seven Bridges of Königsberg puzzle, cracked the Basel problem that had stumped Europe's best minds, and reformulated Newton's mechanics to handle rigid bodies. His work stretched from fluid dynamics and optics to ship design and the bending strength of beams. He standardized notation that survives unchanged — π for circles, e for the natural base, i for the imaginary unit — and d…