In 1960, Mikhail Botvinnik was the pillar of ‘‘scientific’’ Chess and the iron-willed champion of the world. The young attacking genius Mikhail Tal, the ‘‘Wizard of Riga’’ put the magic back into the game by defeating Botvinnik with spectacular tactics in one of the most dramatic and celebrated world championships matches of all time. When Tal beat Botvinnik for the world championship in 1960, he was 23 years old at the time and the youngest world champion ever.       --Al Lawrence