André-Marie Ampère (1775–1836) was a French physicist and mathematician, largely self-taught, who founded the science of electromagnetism almost overnight. His life was marked by tragedy — his father was executed during the French Revolution — yet he poured himself into learning, devouring an entire encyclopedia as a boy. Today his name is on something you use every day: the amp.
When Ampère heard that an electric current could deflect a compass needle, he raced home,
did the experiments within weeks, and worked out the maths linking electricity and
magnetism. He showed that two wires carrying current attract or repel each other, and gave
us the law describing it. The ampere — the standard unit of
Ampère was famously scatter-brained. One story has him mistaking the back of a passing carriage for a blackboard and chasing after it, chalk in hand, scribbling equations. On another day he's said to have used his pet cat as a hankie. Whether every tale is true or not, he was so lost in thought that "absent-minded professor" might as well have been invented for him — and yet from that whirl of distraction came one of physics' most precise and enduring laws.