WERNER HEISENBERG (1953)

https://www.mediatheque.lindau-nobel.... Developments and Difficulties in the Quantum Theory of Elementary Particles (German Presentation) Werner Heisenberg came to his first Lindau meeting with a very interesting and topical physics lecture about elementary particles. Regretfully, only the second part has survived on tape, but the full lecture can be read in a transcription of a set of short hand notes taken (on July 2 at 3 pm, 1953) by a Munch PhD named Winfried Petri. That Heisenberg also was a talented speaker, can be heard from the second part of the lecture. The first part describes the development of the theory of atoms and elementary particles, starting with the Greeks and leading up to the Rutherford-Bohr atom of 1912, Heisenberg-Schrödinger quantum mechanics of the late 1920’s and the quantum electrodynamics first formulated by Paul Dirac in the 1930’s. But Heisenberg’s talk is far from being only a historical overview. In a quite remarkable way he manages, without any equations, to describe his own ongoing attempts to formulate a unified theory of elementary particles. In his theoretical framework, energy is the main parameter and can under suitable circumstances give rise to any particle. Then quantum electrodynamics, which is a theory of the interaction of electrons, positrons and photons, becomes a theory that can be separated out to hold for low enough energies only. For higher energies, where heavier particles can be produced, the theory fails. In the second part of the lecture, which can be heard here, Heisenberg then brings his discussion up to his own 1953 research frontier. Interestingly enough, he returned to the physics meetings in Lindau to lecture on updates of the same theme, a unified theory of elementary particles, in 1956, 1959 and 1962. In order to distinguish between several possible theories, Heisenberg in his 1953 lecture makes a plea for much more experimental data. He mentions that high-energy collisions can be studied in balloon experiments using cosmic rays or in man-made accelerators. It is an extra bonus that at the end of his lecture, Heisenberg mentions that on July 1, 1953, i.e. the day before his lecture, an agreement among European countries to build an atomic physics institute in Geneva was signed in Paris. We know today, of course, that this “atomic physics institute” became CERN, the world leading laboratory today for high energy physics! Anders Bárány