How Quantum Mechanics turned out not to be a Theory of Everything (1925-1932)

When quantum mechanics was constructed a century ago, many physicists expected that it would not just provide a theory of atomic, molecular and solid-state physics, but that it would also answer ultimate questions about the structure of the elementary particles and thus provide what we would now call a "theory of everything". In my talk, I will show how these hopes were dashed and how physicists like Werner Heisenberg, Wolfgang Pauli and Niels Bohr instead came to expect one last great revolution in physics – a revolution that would finally unveil the basic structure of matter; a revolution that we are still waiting for today.