Werner Heisenberg (1971) - Physical and political considerations in the construction of large particle accelerators (German presentation)

Ladies and Gentlemen, we physicists not only deal with such fundamental and important problems like the ones Paul Dirac explained to us yesterday. And not only with the material difficulties which the experimentalist has to solve in order to achieve his results, like the ones we heard about yesterday from Mr. Hofstadter. We have recently also frequently been asked, by young students in particular, about the relationship between our science and society. The society which our research should directly or indirectly benefit and which in return has to bear the high cost of our research work. Since there is always a danger that one becomes lost in fundamental debates or ideological ideals when answering such questions, I think it is useful to explain the practical side of this issue with the aid of a very special example. In recent years there has been a lot of talk about a large accelerator which is soon to be built through the joint efforts of various European countries and their engineers and physicists. There have been differing opinions and public discussions about the urgency of the project, its funding and its future location. But finally it was agreed a few months ago to build the accelerator in the European Nuclear Research Centre in Geneva, and that a number of European countries, among them France, Great Britain, Italy, the Federal Republic of Germany, will participate in the funding and the operation. All important decisions regarding this controversial project have been taken, and there is therefore no longer a danger that I could intervene in a pending process with my comments. I believe that the majority of those involved, and by this I mean the physicists as well as the representatives of the participating governments, in the Federal Republic as well as in other European countries, that they are largely satisfied with the result. This is precisely why it can be interesting to once again list the points of view which have played a role in the decision. After all, there may be similar large joint projects in the future as well, and the same questions about the relationship between science and society, about what is necessary for international scientific collaboration, will resurface then. It is therefore possible to learn from the negotiations of the past three years and I want to use this special example of the European large accelerator to express a few more general thoughts on the relationship between government and science and on the type of collaboration which is possible here. First a few words about the physical problems which are to be addressed with the aid of the large accelerators. Advances in atomic physics during the last 100 years have always been closely linked with larger and larger accelerators, where I now want to use the term accelerator in a very general sense. For the conventional discharge tubes, for example, such as the fluorescent tubes of neon advertising signs, it is sufficient when electrons pass through a voltage of a few volts in order to be accelerated so that they can change the atomic shell of the gas atoms present in a collision and excite them to emit light. Their energy is thus a few electronvolts, to use the term we physicists use. Such electrons have been used to investigate the electron shell, and the rules according to which they are built were ultimately found. Atomic shell here is deemed to be the totality of the electrons orbiting the atomic nucleus. The binding energies in the atomic nucleus are around one million times higher than in the shell. At the beginning of the 1930s, Cockcroft and Walton in Cambridge built a high-voltage device with which they were able to accelerate protons to energies of the order of one million electronvolts. They were therefore able to change light atomic nuclei, knock out elementary particles from them or incorporate other elementary particles into them. And during the 1930s we thus learned to understand the structure of the atomic nuclei, which, as has been known since then, consist of two types of elementary particle, the hydrogen nuclei or protons and the neutrons. The next largest group of such apparatus, which can already be called large accelerators, was built in the 1950s. They were to be used to give protons an energy of the order of a billion electronvolts, the so-called GeV. The hope was that it would even be possible to use them to change the elementary particles which were known at that time, to possibly decompose them into even smaller fragments, to find even more elementary building blocks. These large accelerators, which include the devices in Berkeley, Geneva, Hamburg, Brookhaven, Serpukhov, also fully fulfilled the expectations placed on them. It turned out that it is indeed possible to change elementary particles, to put them into excited states, even split them into many parts. But, and this was the decisive new thing, the fragments here are not smaller than the particles that one forced to collide. Rather, it is no longer really the process of splitting, but the formation of matter from energy, and from the theory of relativity it was known that this was possible. In such high-energy collisions elementary particles of the same spectrum are formed again and again. The elementary particles are, it can be expressed in this way, simply different forms into which energy can convert in order to become matter. But apparently there are then no particles which are even more elementary. This was the status of experimental research a few years ago, and on the basis of this knowledge a decision had now to be taken as to whether even larger accelerators with energies of the order of a few hundred GeV and correspondingly very high costs should be built. The simple consideration that every transition from smaller to larger accelerators had brought new findings supported this step initially. Why should this not continue? Entering a new range of energies had inevitably to lead to new, as yet unknown information, and nobody can exclude that quite unexpected, surprising and interesting information would result. But even if one excludes such surprises, it can be important to know how the interaction which is crucial to radioactivity behaves at high energies, for example. This is because the previous experiments do not allow a reliable assumption and it is quite possible that the knowledge of this behaviour leads to fundamental progress in the understanding of the spectrum of the elementary particles. Here, with the arguments for the accelerator, the key significance of this complex of problems for physics overall must be emphasised. It will ultimately be possible to trace back all physical laws to the laws for the behaviour of the smallest material particles. It is therefore very important to find out about these laws in particular. But even if one does not place such high value on the extension of elementary particle physics, there will be new technical experiences during the construction of the huge accelerators which can be of practical use in quite different areas. One has to approach the extreme limits of the technically possible in each case with these accelerators. It is therefore possible to learn a great deal for practical applications. I remind you for example of the technology of superconducting magnets, which is now developing and which can possibly be used to the full in the new large accelerators. There are therefore good arguments which speak for constructing such large accelerators with energies of the order of 300 GeV or more. And if one could construct such devices for a few million Deutschmark, probably nobody would have doubted that it needed to be done. Unfortunately the costs run into billions. And therefore, out of consideration for the other requirements of the state, one has to ask whether it is not possible to reduce these enormous costs or at least postpone them to a later date. Are they really absolutely necessary? In respect of these doubts, one can first state that the arguments that something fundamentally new will result at higher energies are not quite convincing. After all, nature has provided us with a new and unexpected piece of information especially with our attempt to split elementary particles, i.e. that it is not the splitting, but the conversion of energy into matter which plays a role in these processes. This will probably be the case at higher energies as well, and one therefore has to expect that even for an arbitrary increase in energy nothing new will happen. In addition, particles with extremely high energies have already been observed in cosmic radiation, up to 1 million GeV, and no fundamentally new phenomena have been found for them. One could also point out that the storage rings in Geneva, which go into operation this year and which have now been built in the last few years, that they also would reach to even higher energies. It could therefore be the case that the current extensive experimental material on the elementary particles is already sufficient to completely understand the laws of nature in this field, that we do not necessarily still need the extension to these higher energies. Indeed, it is difficult to imagine that a theory which was initially put forward hypothetically could correctly explain all our experiences to date within the experimental limits of accuracy, but that it could then fail nevertheless in the area of even higher energies, which we do not yet know. But even if one believes that experimenting at these high energies is absolutely necessary, one could still hope that the technology, that of the superconducting magnets, for example, will have made so much progress in a few years or decades and that new types of design principles will have been found to enable the large accelerator to be constructed at a much lower cost. Such arguments could thus be used to plead for waiting with the construction of the large accelerator, at least for a couple of years. You see that the physical and technical arguments alone would hardly be sufficient to take a clear decision, and therefore one also has to carefully consider the science policy and foreign policy components of such a decision. Let us start with the effects of such a decision on higher education and research policy in Germany: the sums which have to be spent for a large accelerator of 300 GeV or more are so large that, even if it is an international joint project, they cannot simply be provided in addition to the existing research budget, simply to the detriment of all other budget costs, for example. For the society or the government which represents it this means very unpleasant issues of priority, in the following form, for example: should we establish another new university, given that the teaching capacity of our universities is too low, or participate instead in an international large accelerator project? Or a different question: should we use a few hundred million per year more for environmental protection, keeping the rivers, lakes and the air clean, or should we use them for elementary particle physics? Here in Lindau, in particular, we have one of the most convincing representatives of environmental protection in our distinguished Count Bernadotte. These questions are so unpleasant because it means we have to compare the urgency of completely incomparable issues. On the one hand we have the pure knowledge about fundamental issues of physics and the natural sciences, which can later also possibly have considerable economic impacts, albeit only indirectly. On the other is a direct practical need of life today, for example the option of later having the children educated in a university and creating healthy living conditions for them. So how should such issues be decided? The first demand which must be made here appears to me to be that the physicists who want to have the large accelerator and work with it also have to understand the entire difficulty of these problems. It is not enough to push the question away with the remark that it is the government’s responsibility to consider this, or to casually say that the amount for the large accelerator should be deducted from the defence budget. For those people who bear the responsibility for society, the issue of the security of this society must carry a higher weighting – it must do – than the participation in a large project to study elementary particles. In other words: political issues which the physicists cannot simply ignore either unfortunately come into play in the decision on the construction of a large accelerator. The British physicists have provided a very good example of how a physicist can behave here. If I have been informed correctly, the British physicists have proposed to their government that it should participate in the European large accelerator project, but should at the same time, in order to balance costs, reduce the budget for elementary particle physics accordingly. There was even a discussion that a large and renowned research institute in the same field, the Rutherford Laboratory in Cambridge, could be closed down. Behind such a proposal is therefore, on the one hand, the conviction that the experiments which one will be able to carry out with the new European large accelerator are more interesting and more important than those that could be carried out with the smaller devices in the Rutherford Laboratory. On the other hand, there is also the realisation that the physicists have possibly already made relatively high demands in past decades on the economic power of their country, so that one had to be extremely careful in making even greater demands. The British physicists have therefore very carefully considered the well-being of the society to which they belong in their requests to the government. May I include a general remark here, which may not quite belong here? It seems to be an unfortunate development of our time, certainly not just in our country and quite certainly not only among us physicists, that many are tempted to make demands on the state without making a reciprocal offer or offering a sacrifice of their own. This may be an entitlement to education, grants, co-determination in difficult issues, or even simply the entitlement to a large amount of leisure time, holidays to distant destinations and material wealth. Again and again the tendency is becoming apparent to think that it is not necessary to make sacrifices themselves to justify these entitlements. But the good example of the British physicists which I have mentioned points to the general question as to what actually the relationship of physicists or scientists in general to their governments should look like. Most people seem to agree that, at the moment, the work of the government requires the advice of science. Science and technology play such an important role in modern life, in industry, in educational issues, in the preparation of political decisions, that there must be advisory committees of scientists and engineers which facilitate the work for the government. And, in fact, everywhere in the modern industrial states such advisory committees have been established. In Germany, advisory circles exist on different levels, and they assist the government with the distribution of public funds for research purposes, with decisions on large research and development projects, with university issues etc. I remind you of the nuclear committee, the scientific advisory committee of the economics ministry, the advisory committee for research, for example. In recent months, in particular, there has been much discussion about the reform of these advisory groups. In addition, there are naturally, and this is something completely different, interest groups in the government sphere, which have been sent to our capital, Bonn, from parts of industry, e.g. specific branches of industry or agriculture, for example, in order to make themselves better heard. But this is quite legitimate in a democracy, because it is the very task of the government to find a balance which is as just as possible between the various interests of the citizens of the country. It is therefore important that the state knows these interests. It seems to me to be extremely important that the difference between the advisory groups and the interest groups does not become blurred. At the very moment that an advisory group becomes an interest group as well it ceases to be a useful advisory group, because only completely impartial advice can be really beneficial to the government. This now gives rise to a difficult dilemma when it concerns the government’s participation in a large, international technical research project, such as the planned large accelerator, for example, because, on the one hand, it is imperative that they are advised by specialists in the field of high-energy physics, because only they can really assess the details. On the other hand, these specialists are inevitably also interested parties, because they or their students want to work at the large accelerator later. This difficulty cannot be avoided. Obviously, the British scientists whom I mentioned before also felt like this, and these physicists then tried to make a sacrifice in relation to their interest in order to play the role of the advisor with a clear conscience. But even when the fullest understanding of all concerned can be expected here, when all the previously mentioned conditions are fulfilled, it still remains a very difficult task to assess the urgency of such a techno-scientific project against other projects. How important is scientific knowledge? How important is it that it is gained soon and not only in 10 or 20 or 30 years time? Now, if you have spent your life in science, you will treasure the value of scientific knowledge, and you will be able to cite many good and compelling reasons for this. A politician, however, who worked as a businessman or farmer before they entered politics, will maybe consider economic issues or environmental protection to be more important, and they will also find many convincing arguments for this. On the other hand, they will maybe fall into the trap of valuing scientific knowledge too highly, because science is weird and strange for them, and because they then overestimate its possibilities because they are impressed by modern technology. Given the politician’s inevitable uncertainty, the advisers’ main duty is naturally to provide the authorities with a completely objective, truthful picture of the scientific plans and their assumed importance. All the reasons for, but also all those which argue against the project, must be presented and explained as factually as possible so that the politician receives the maximum information possible in the particular case. When listing and explaining the reasons which argue for or against such a project, one has to ensure that the burden of proof is correctly distributed. If it is a project costing billions, whose start inevitably requires sacrifices in other places, those who champion such a project must provide the proof of the urgency of the results hoped for. And it cannot be their opponent’s responsibility to prove that the project is really not so important, because for a project which ventures into new scientific territory it will never be possible to prove that no new, surprising and important discoveries will be possible. But this on its own cannot possibly be sufficient as the reason to spend billions. The burden of proof must therefore always be with the party which wants to obtain such extremely high public funds. But even then the decision will still be difficult enough for the politicians. The fact that corresponding decisions have also to be taken in the other countries thus alleviates their work. It is then possible to be guided by what the others have considered. If it is an international project such as the planned European large accelerator, the other member states which possibly want to participate are even facing exactly the same problems. Here it is therefore necessary to take the decision jointly, more or less. The international character of such a large project means some new aspects come into play which I have not discussed so far. First of all, we all probably agree that it is extraordinarily important for the future of our continent that a real community develops from the many small European states. A large scientific project, whose significance is recognised by all, but which can no longer be borne by one individual European country on its own due to the high costs, this represents an ideal case of such collaborative work as it were. Because where pure science is involved, economic or political competition no longer plays an important role, results and technical know-how do not need to be kept secret. The mutual interest in exciting scientific problems makes young physicists and engineers from very different countries automatically come together for fruitful work. And without any further effort a continuous exchange of opinions takes place and thus unconsciously a balancing of interests, which cannot be valued too highly for the future goal, the unity of Europe. Such international large projects must therefore really be funded just because they are international. One must therefore not be overly critical and sceptical about the scientific possibilities and reasons, given the community-forming force. In fact, in the 25 years after the war a number of such community projects and joint institutions, which have become very important for the collaboration, have been established in Europe. The best institution of this kind is probably the CERN Nuclear Centre in Geneva. A 30 GeV proton synchrotron has been in use there since 1959 and has already made a number of very interesting experiments possible. This year or next the large storage ring will be in full operation, which even corresponds to an accelerator of around 1700 GeV as far as the energy in the collision of two protons is concerned. It will be the only instrument of this type on Earth and a few months ago, as I said, it was decided to construct a new European large accelerator in Geneva with several hundred GeV. Europe will therefore be playing a leading role in elementary particle physics, or high-energy physics as it is also called, during the next 10-20 years if these machines are utilised as well as the proton synchrotron in Geneva to date. In Trieste, i.e. on Italian soil, a very successful international centre for theoretical physics has been established which is funded not only by European, but also by non-European countries, and which maintains particular good connections to Eastern Europe and Asia. In Ispra on Lago Maggiore, also on Italian territory, development and research tasks in the field of reactor technology are being conducted on behalf of EURATOM. This is also a large international joint project, to which various European countries contribute. Franco-German collaboration has led to a reactor with very high neutron flux being constructed in Grenoble in France, where scientific and technical investigations of the behaviour of materials under strong irradiation can be conducted. Similar international institutions working in other fields, e.g. the study of space, exist in Belgium and the Netherlands. There is thus considerable interest in international scientific collaboration and one can be quite satisfied with the successes which have been achieved in the different institutions. Nevertheless, if one wants to decide to establish a further such international scientific institution, difficult problems again arise, which mainly concern the location, but also the funding, the distribution of the contracts, the filling of the leading positions. The issue of the location is by far the most difficult here, because it must usually be decided not on factual aspects, but on political ones, although the desired technical or scientific objective often imposes conditions which greatly limit the options for the location. For example, a large accelerator requires a wide, level area which is geologically stable, i.e. which is not buckled if the ground is moved or deformed under the influence of the weather, and the earth movements necessary to construct the accelerator must not be too expensive either. Furthermore, the planned institution must be easily accessible. It must be easy to get to schools, universities etc. So there are quite a number of conditions which must be fulfilled, but it is usually not too difficult to find sites in very different regions of Europe where all these conditions are fulfilled. It finally remains to take a political decision and one has to ask which aspects play the most important role here. The establishment of these various international scientific centres is, of course, a community effort and a joint European effort and this means, in my view, that these institutions should be spread more or less evenly across Europe. One can, of course, discuss what this vague term “more or less evenly” means. But I believe if one looks at the map of Europe and considers the spatial distribution of the international scientific institutions to date, one can see that the spread is still quite uneven and should become more even in the future. Objections to this argument are sometimes that our objective should of course be the United States of Europe and that the location within Europe would then not be important. But the example of the United States of America shows that this is not the case. Even in such a politically unified large area one has to take care that the scientific institutions are evenly spread. The newest American large accelerator, which is to achieve around 400 GeV, is being constructed in Batavia near Chicago, after the two earlier centres for high-energy physics were established in the west in California and in the very east in Brookhaven. The location issue has played an important role in Europe in the deliberations on the large accelerator mentioned above. But the possibility of using the existing infrastructure of the CERN centre in Geneva and thus reducing the costs significantly has ultimately taken precedence over the other option, to establish a new European research centre in a different region which is far removed from the current centres of this kind. Let us hope that future establishments will provide a more even distribution across Europe. There was another reason to move the new large accelerator to Geneva again into the CERN centre. A new European centre for high-energy physics independent of Geneva would have bound thousands of staff to the new location and to this work at a new large accelerator. Many young, talented physicists and engineers would have turned to this very special field of elementary particle physics and accelerator technology and would probably have been so captivated in this field by the problems in the years to come that they would have found it difficult to later work in a different field. On the other hand, this special complex of problems of elementary particle physics would come to an end sooner or later, as all the earlier fields of physics have been exhausted at some time and have then simply been incorporated with their applications into the technology which followed. If this conclusion is moved mentally into an interminable distant future, as some physicists do, one may take this as justification for giving no further thought to the future work of the elementary particle physicists in other fields. But the experience in the United States teaches us that accelerator stations have already been closed there, that physicists and engineers working in them have been made redundant. This means that one does an injustice to young people who one convinced to be interested in these special fields if one does not contemplate their more distant future. For this reason it was surely a wise decision to build the new large accelerator which had been decided in Geneva again, as the proton synchrotron and the large storage ring before it. Although the new tasks mean the staff in Geneva will certainly increase significantly, it will probably be nowhere near the extent that it would have been in an entirely new accelerator station. Selecting Geneva as the location has also slightly reduced the dangers for the distant and near future. And finally a further argument, more in passing. The lack of space on the construction site in Geneva also has a technical consequence. It forces the designers to use the most modern technical developments, e.g. the super conducting magnets, if one wants to achieve such high energies in such a narrow space. The new project will therefore be forced to be much more modern than the one planned earlier. With this I have, I believe, exhausted most of the arguments which have played a role in the decision ultimately made, and which I now repeat in a few words. There is first the joy about a sensible community project, but also the insecurity about the successes to be expected with the new instrument. The question whether the experiences gained with the accelerators to date could maybe already be sufficient to understand the world of the elementary particles. Then the further question regarding the advances in technology: might it not be possible to build accelerators with the high energy required much more cheaply than today in a few years time using new technical methods? And furthermore, the difficulty of obtaining a fair agreement between the participating nations on the location, and the necessity that each individual government has to forego specific plans or projects in their own country for the benefit of the international accelerator. If one considers all these difficulties and problems, the decision which has been finally taken and which you know is a very good solution, in my view, an appropriate compromise between the different interests and a valuable contribution to strengthen the European community. Finally, I have to descend from this level of practical considerations, of scientific reasoning and political negotiations onto a slightly lower level and ask: why do we humans undertake such enormous efforts in order to construct a large accelerator at all? Why do we spend billions on a scientific instrument which does not promise an economic benefit, at least not immediately? For this question I have ...

Werner Heisenberg (1971)

Physical and political considerations in the construction of large particle accelerators (German presentation)

Werner Heisenberg (1971)

Physical and political considerations in the construction of large particle accelerators (German presentation)

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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.

David Siegel

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