Kurt Gödel published 'On Formally Undecidable Propositions of Principia Mathematica and Related Systems,' proving two revolutionary theorems in mathematical logic. His work showed that any consistent formal system capable of expressing basic arithmetic must contain true statements that cannot be proven within the system, and that such systems cannot prove their own consistency. These theorems shattered the dream of a complete mathematical foundation and established fundamental limitations of formal axiomatic systems, influencing computation theory, artificial intelligence, and philosophy.