From 1953 to 1973, Werner Heisenberg participated in 15 Lindau meetings. The golden thread running through most of his talks is the development of a “Unified Theory of Elementary Particles” (which corresponds to the colloquial GUT, the Grand Unified Theory). This ambitious post-war project, as is well known by now, unfortunately led to a scientific dead end. Today, the so-called Standard Model represents the level of our understanding of particle physics.
In 1971, however, Heisenberg chose a very different, almost political topic for his lecture: the Pros and Cons of building new, very powerful (and very expensive) particle accelerators. Heisenberg discusses this issue against the backdrop of the recent decision of several European states to build what was later known as the Super Proton Synchrotron (SPS) at CERN in Geneva.
According to Heisenberg, a prime argument for more powerful particle accelerators is the fact that historically, each pronounced increase in particle energy has brought new fundamental scientific results: while the eV-energy range, accessible with simple vacuum tubes, merely allowed for the spectroscopic characterisation of the atoms’ electron shells, the first high voltage accelerators to be introduced in the 1930s (with a million times higher energy range) already enabled investigations of the atomic nucleus. In a next step, the commissioning of the first “huge” particle accelerators in the 1950s boosted the accessible energy 1000fold to the GeV range and thus made possible the production of an entire zoo of new particles, amongst them the hadrons and the antiproton/antineutron.
Eventually, the SPS, which should go online in 1976, five years after Heisenberg discussed its Pros and Cons in Lindau, went up to energies of 400 GeV. After a modification into a proton-antiproton collider, this allowed for the detection of the W and Z bosons, thus corroborating the electro-weak unification theory, by which these particles were predicted. Carlo Rubbia and Simon van der Meer received the 1984 Nobel Prize in Physics for their work in this field. And it did not end there. Today, an updated version of the SPS serves as a pre-accelerator for the Large Hadron Collider (LHC). The latter delivers energies of 7 TeV to protons and is the key tool in the ongoing efforts to detect the Higgs boson. So after all, it appears as if Heisenberg was right, at least if one takes a solely scientific stance. But was it worth the original SPS budget of 1150 million Swiss francs, corresponding to more than € 3 billion today? Or would it have been better to found and finance several new universities instead? Or to invest the money in environmental protection, as Heisenberg asks rhetorically in his lecture.
His own position is patently obvious: it would probably be worth having these accelerators out of scientific curiosity alone. Still, Heisenberg also gives some additional Pros, which might appeal to a wider, non-scientific public. There is the assumption, for example, that the construction of such a huge and technically sophisticated instrument itself would lead to new scientific and technical innovations, which could be of benefit to society. And then there is the idea of European and even global integration. Today, CERN is run by 20 European member states and scientists of more than 100 nationalities use its facilities collaboratively. What seems unspectacular from a modern point of view was certainly a visionary encounter in the 1970s, which stood under the influence of the cold war, the war in Vietnam and the German separation, for instance. In his talk, Heisenberg raises the point that fundamental research is free of economic aims and direct national interests and that the SPS could be an ideal showcase in this respect. Unfortunately, he was not able to see his scientific and political predictions come true. Werner Heisenberg passed away on the 1st of February 1976, just a couple of months before the first proton beams began to circulate in the SPS.