Wolfgang Pauli had formulated the exclusion principle by the time he was 25. Werner Heisenberg was only 23 when he discovered matrix mechanics and just 25 when he developed the uncertainty principle. Paul Dirac’s reconciliation of quantum mechanics and special relativity came when he was 26. All three eventually received the Nobel Prize for work they had done before the age of 30. Their revolutionary discoveries in the 1920s inspired the term Knabenphysik—boys’ physics—and Segrè describes “the curse of the Knabenphysik, the notion that one should have done something of significance before turning thirty.” The causes of decline are mysterious:
Maybe you stop believing you can change the world, or maybe you realize more quickly that a crazy idea is just that and do not pursue it as vigorously. Maybe you can’t assimilate new material as rapidly as you did when you were younger. Perhaps, having set a new course for physics once, you experience a psychological and intellectual resistance to shifting direction again.
For older physicists—like Einstein, whom the younger generation revered but ignored—it wasn’t easy to keep up. And even for the revolutionaries, the transition from being prodigies to professors was difficult; neither Pauli, Heisenberg, nor Dirac achieved anything nearly as important after turning thirty as they had before.
