The Pythagorean who broke the silence — and maybe paid the price. Hippasus of Metapontum (fl. 5th century BCE) is often credited with discovering irrational numbers, which, according to legend, got him expelled from (or drowned by?) his fellow number mystics. In a world where math was supposed to be perfect and whole, Hippasus found something terrifyingly in-between. Whether fact or fable, his story marks a moment when mathematics cracked open — and the infinite crept in.