The European: When we spoke last year, you had just initiated a round table to pursue a dialogue between the natural sciences and the humanities. How is that going?
Heuer: We are working with Wilton Park to hold a conference in October to examine the interface of knowledge and move towards a common language. The question is: do we really understand each other when we discuss our respective work? Do we speak about the same things, or do we interpret too much into our colleagues’ words?
The European: What frictions exist?
Heuer: How can we define “knowledge”? Where does knowledge end, and philosophy or religion begin? Even a word like “discovery” can mean very different things to different people.
The European: A propos: a lot has been written in recent months about scientific concepts like the “5 sigma” evidence level. How certain are you that you’ve found the Higgs boson?
Heuer: It’s normal that scientists only use the term “discovery” beyond a certain threshold of statistical certainty. “5 sigma” means that some phenomenon cannot be dismissed as a statistical fluctuation with a probability of 99.99994 percent. In the world of physics, we have agreed that we’ll only speak of “discoveries” if we can clear that hurdle. That is also the reason why we were very careful in our statements: we don’t like to speak of the Higgs boson yet but prefer still to call it a “Higgs-like particle.”
The European: Do you think that the media coverage has contributed to a deeper understanding of the natural sciences? For example, the realization that a physicist and a journalist might define “discovery” very differently?
Heuer: I think so. The general public and journalists now see that scientific results – especially in basic research – don’t simply drop from the sky but have to grow slowly. Progress isn’t a linear development, we always encounter retrograde steps as well. If you look at our work and media coverage over the past year, you can really see that: last fall, we were still at the “3 sigma” level. In December, we were able to substantiate our observations and this July we managed to push beyond the “5 sigma” threshold. Once that happened, we had the responsibility to inform our sponsors and the scientific community.
The European: Do you feel like you have to dumb down your work for public discourse?
Heuer: That would be the wrong approach. But we have to differentiate between scientific work and the presentation of our work and results to the public. We owe it to the public that we communicate well: our work is interesting, important for the progress of science, and often publicly funded as well. The thing to keep in mind is the right order: first, we inform our colleagues in the scientific community, and then we find a language that is suitable for the general public and the media.
The European: There’s been a sudden outburst of interest in your work. What do you think explains that?
Heuer: The challenge in basic research is always that we cannot lure you with practical applications of our work. That makes it hard, especially when the economic situation isn’t good. But I think we now see that many people are really interested in questions about the early universe. That’s a very human tendency – we have all thought about questions like “How did it all start?” or “How did the universe develop?” That’s exactly where the discovery of the Higgs boson fits. And after years of preparation, we’ve also gone through a period of suspense over the past 12 months: could we make it above 5 sigma or not?
The European: You have criticized the term “God particle” from a scientific perspective. But I wonder whether the metaphor still has a value, for example, by conveying a sense of the elementary nature and importance of the particle?
Heuer: I think so, and I have grown accustomed to the term. Even scientists aren’t immune to the effects of catchphrases that help us to increase the exposure of our work. One version of the term’s origins goes like this: Leon Lederman wanted to call his book “The Goddamn Particle” because the search for the Higgs seemed endless and futile. His publisher supposedly objected and shortened the title to “The God Particle.”
The European: And science isn’t distorted through such terms?
Heuer: We have to be careful. Sometimes it sounded a bit as if the Higgs had a connection to God or as if it dated back to a time before the Big Bang. As scientists, we have to argue against those claims. “God particle” is only a catchphrase and doesn’t tell you anything about the content of our work.
The European: How will the discovery of the Higgs change the course of physics over the coming years and decades?
Heuer: The “standard model” chapter is now done within the energy range (or reach) that is accessible to us. It is now internally coherent. But that only encompasses the visible universe: 95 percent remains unknown to us. The next task is to measure the properties of the particle very precisely. Maybe we’ll encounter deviations from the theoretical predictions of the standard model that might indicate where we have to look next. Maybe we’ll learn more about supersymmetry, dark matter or even dark energy. If nature means well, the Higgs boson will open many doors towards future discoveries.
The European: A hypothetical question: What would have been more important, the discovery of the Higgs or the confirmation that the particle did not exist?
Heuer: The fact that we have found it is extremely gratifying. We have confirmed a 45 year old formalism. That’s gigantic. If we had been able to rule out its existence, that would have been very important as well because we would have been able to say: “Something is missing in the standard model.” But it is always easier for a scientist to positively confirm something than to rule something out. When you confirm the existence of a particle, you have very concrete starting points for future research. If I were a salesman, I would tell you: a Higgs sells better than no Higgs.
The European: Many questions that came out of the standard model are decades old. Are we now at a point where most of them have been answered, and the focus shifts to a new generation of questions?
Heuer: Einstein introduced the cosmological constant in the early 20th century – and today, we look at the value of the constant and have been calling it dark energy for about ten years. So some questions are very old. But it is true that the discovery of the Higgs means that we will address elementary questions with a new bout of courage. Higgs boson and dark energy are both scalars, mathematically speaking. That means that they are solely defined by their magnitude, not by their direction. It is possible that we have now found the first elementary scalar – the Higgs particle – and that the discovery will teach us more about the physics of dark energy.
The European: So the large particle accelerators cannot be retired quite yet?
Heuer: We will finish our next big improvement by 2015. Then, we will be able to reach much higher energy levels – 13 or 14 TeV, compared to today’s 8 TeV. That opens new doors for experimental research in two ways: one, it allows us to create particles with higher mass; two, it increases the resolution of our microscope. 2015 will be a very interesting year.
The European: Does the future still lie with experimental physics, or will you eventually reach a situation where progress comes mainly from the development of theoretical physics?
Heuer: The balance between experimentation and theory cannot really shift. If you postulate a theory, you must somehow be able to prove that it is correct. A theory might perfectly describe what you can see around you, but there is no guarantee that it remains valid at higher energy levels, for example.
The European: Are the limits of physics prescribed by the limits of our experimental setups?
Heuer: Let me put it this way: you can always postulate different theories that all match today’s observations. But they might extrapolate into higher energy levels in very different ways. Think of it spatially: one theory goes left, one goes straight, and one goes right. The more exact your measurements are, the more you are able to isolate the potential direction of the most appropriate theory or discount theories that clearly show a different direction. I say this as an old experimental physicist: you can’t do without measurements. I want to see things confirmed.
The European: That brings us back to the differences between the natural sciences and the humanities. A philosopher might say: what matters is the internal coherence of a theory.
Heuer: That is precisely one of the problems we have to discuss. Should we regard something as valid even if we cannot prove it? It’s an exciting point of contention where the physicist might reply: “anything that cannot be proven remains a theory.”
The European: And the theologian answers, “I know because I believe.”
Heuer: Do I know something because I believe? Or do I believe what I believe? You see, you are talking about the nature of knowledge itself, and about the differences between knowledge, faith, and feelings. When should we speak of “knowledge”? I am very curious about the answers we might get.
The European: Do you think that scientific insights are less visible in political and societal discussions today than they used to be?
Heuer: I think that our sensitivity for scientific questions has decreased. That is why the current debate about the discovery of the Higgs boson is so important for scientists. The fact that people now consciously speak about “probability” can help us to make scientific thinking more prominent.
The European: Should scientists be more vocal in the public sphere?
Heuer: If they have right things to say, yes. When we make important decisions, we should be able to rely on sound premises and statements. Just babbling isn’t so good. I also believe that science can really provide an example for cooperation that works. “Diversity” is such a nice word, such a nice mix of different ideas and characters. We can show that diversity enriches us.
The European: In the middle of the Eurozone crisis, you head a European institution that has worked rather seamlessly for almost 60 years. Is basic research possible on a strictly national level?
Heuer: Our research would be impossible without a collaborative element. The infrastructure necessary for basic research has gotten so big – at CERN but also e.g. in the case of electron lasers. You need many brains and hands to build it – that’s impossible on a national level. CERN was founded in 1954, when a bunch of scientists and politicians got together right after World War II and said: “we will only be successful together.” The decades since then have confirmed that approach. I think that we will even have to go further in the future and cooperate globally.
The European: In addition to the democratization of knowledge, we need the globalization of research?
Heuer: Some people call our particle accelerator LHC a “world machine.” I quite like that, because the LHC is a machine for the world and used by researchers from around the world. Maybe we will have to rethink what we mean by the term in the future: research can happen simultaneously around the globe and be made available to the whole world. The language of science is universal, so this tends to work rather well. The challenge is to see political and cultural differences not as threats but as enriching experiences.
The European: The re-nationalization of Europe is the wrong way?
Heuer: I think it goes in the wrong direction. We need something that we can work on collaboratively. And we also need projects that we can pursue individually – often, those are smaller projects. Take food as an example: it’s good to introduce certain standards, but we should not give up regional cuisines. We need to strike a balance between international large-scale projects and smaller, national or bilateral projects. You won’t get very far if you only pursue lighthouse projects.