Werner Heisenberg (1901-1976).

Autograph manuscript, 'Entwicklung der Theorie des Elementarteilchen' (Development of the theory of the particle), draft of a lecture given at Eotvos Lorand University, Budapest, 5 March 1964.

In German, 2½ pages, 295 x 209mm (biographical note in Hungarian on blank f.2v).

On particle physics and the significance of unified field theory. The manuscript is divided into three parts: 'I. The variety of forms of the world of particles... II. What is the significance of unified field theory for particles?... III. What has been achieved through unified field theory?'. Heisenberg's overview begins by comparing the field of particle physics with that of nuclear physics 40 years previously, and the remarkable progress made since then, noting however the extreme mathematical complication of the current state of the discipline; he goes on to consider Einstein's failed attempts to achieve a unified field theory which would account for quantum theory within the framework of relativity, and questions whether this failure implies a return to Newtonian physics. In conclusion, Heisenberg speculates that particle theory offers the possibility of settling philosophical questions which date back to Plato: 'In a few years we will know what is the structure of world in its smallest form. I suspect that it is very Platonic. But here there is no speculation: all this will be decided by experimental physicists'.

The occasion of the lecture was the presentation to Heisenberg of an honorary doctorate. The creator of quantum mechanics (for which he was awarded the 1932 Nobel Prize) and formulator of the uncertainty principle, Heisenberg made significant contributions across a number of related fields. The attempt to set particle physics in a Platonic context is highly characteristic of Heisenberg's last decades – indeed, his 1969 Memoirs were written in the form of a Platonic dialogue. Alas, his confidence that experimental physicists would swiftly resolve the cruxes of the world of particles has proved misplaced.

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