The Scientist as Critic
The modern version of quantum theory—now known as “quantum mechanics”— was born and grew to maturity in just five years, between 1925 and 1930. More was accomplished during those five years than in the preceding twenty-five years, or, for that matter, in the seventy years that have followed. Progress before 1925 was constantly hampered by conceptual doubts. Paradoxes such as the wave-particle duality—the contradiction between the Einstein particle theory of light and the classical wave theory—were disturbing and limiting. But by 1925 these difficulties had, perhaps from familiarity, become less inhibiting. Theorists stopped worrying about the conceptual strangeness of the quantum realm, and began to make a new physics with the strangeness incorporated in it. Once the conceptual barriers were passed, progress was astonishingly rapid. For those who had the vision, it was as if a great fog had lifted. Suddenly it was possible to see in many directions with a clarity no one could have anticipated.
Quantum physicists of the new breed began to practice in the early 1920s. They were mostly second-generation quantum physicists, having been born after Planck read his famous paper to the Berlin Physical Society in 1900. (One might fancy that the appearance of Planck's paper was a signal for the birth of a whole crop of gifted physicists: Wolfgang Pauli, Frederic Joliot, and George Uhlenbeck in 1900; Werner Heisenberg, Enrico Fermi, and Ernest Lawrence in 1901; Robert Oppenheimer, John von Neumann, and George Gamow in 1904.) One of the most brilliant and influential members of this talented group was Pauli, who not only made major contributions of his own but also, like Bohr, shaped his colleagues’ work in long, critical discussions. During the crucial years of the 1920s and 1930s, many quantum physicists felt that their work was not finished until they faced Pauli and his relentless criticism, or lacking the Pauli presence, asked the question, “What would Pauli say?”
One of Pauli's assistants, Rudolf Peierls, tells about Pauli's role as a critic: “To discuss some unfinished work or some new and speculative idea with Pauli was