Charles-Augustin de Coulomb (1736–1806) was a French military engineer who turned the invisible push and pull of electric charge into an exact law. His name now lives on twice over: as the law of electric force, and as the unit we count charge in.
Coulomb built a fantastically delicate twisting balance — a charged ball on a thin fibre — to
measure forces almost too small to feel. He discovered that two charges push or pull with a
strength that fades with the square of the distance between them. That rule is the backbone of
Before he was a physics legend, Coulomb spent years in the Caribbean sweating over the construction of a huge fort, wrecking his health in the tropical heat. Back in France he brought an engineer's obsession with friction, twisting threads and structures to the study of electricity. His secret weapon was patience: the torsion balance was so sensitive that a stray draught or a warm hand could ruin a reading, so he learned to sit very, very still.