In 1976, a Computer Cracked the Four Color Theorem—and Mathematicians Rebelled

The Four Colour Theorem: The first time machines mogged mathematicians

In July 1976, Kenneth Appel and Wolfgang Haken announced a proof of the Four Color Theorem, relying on 1,200 hours of computer computation and 10 billion decisions. While some mathematicians celebrated, others rejected the proof as not real mathematics, sparking a fierce debate over whether a proof too vast for humans to verify can be trusted. The divide often fell along age lines: those over 40 doubted the computer, while those under 40 doubted the 700 pages of hand calculations.