Nash Equilibrium

John Forbes Nash Jr. proved in 1950 that every finite game with mixed strategies has at least one equilibrium — a state where no player can improve their outcome by changing strategy alone. This Nash equilibrium transformed economics, evolutionary biology, and political science. In rock-paper-scissors, the Nash equilibrium is to choose each option with probability 1/3 — any other strategy lets your opponent exploit you. Nash suffered from paranoid schizophrenia for decades. He won the Nobel Prize in Economics in 1994 and died in a taxi in 2015 returning from receiving the Abel Prize.