Laureation address – Professor Peter Higgs

‌Professor Peter Higgs
Laureation Address
Laureator: Professor Ifor Samuel
Wednesday 25 June 2014

Vice-Chancellor, it is my privilege to present Professor Peter Higgs for the degree of Doctor of Science, honoris causa.

Peter was born in Newcastle in 1929, and brought up in Birmingham and Bristol. He studied physics at King’s College London, graduating in 1950, followed by his PhD research, leading to a thesis with the title Some problems in the theory of molecular vibrations. He was appointed to a lectureship in Edinburgh in 1960 and has been there ever since, with a Personal Chair in Theoretical Physics since 1980. His contribution to physics has been recognised by his being elected a Fellow of the Royal Society of Edinburgh in 1974, Fellow of the Royal Society in 1983 and an amazing array of prestigious prizes. These include the Dirac Medal and Prize of the Institute of Physics, the High Energy and Particle Physics Prize of the European Physical Society, the Royal Medal of the Royal Society of Edinburgh and, most importantly, the Nobel Prize for Physics last December. He received the Freedom of the City of Newcastle in April this year, and will receive the Freedom of the City of Edinburgh on Saturday

Physics is a much misunderstood subject. I say this because many people do not realise how closely physics links to everyday life – for example in electricity generation and communication – bringing light, television and the internet into our homes. It deals with everyday questions like: ‘What are we made of?’, ‘How are we held together?’, and, ‘Why do we have mass?’. I will give brief answers to these questions in order to explain Peter’s work. We are made of atoms, but if you look more closely the atoms themselves are made up of particles, namely electrons, protons and neutrons. If you look even more closely – and this is the work of particle physicists – you find that the protons and neutrons are themselves made of smaller particles, namely quarks. So ordinary matter is made of only three things. You see, physics is simple. How are we held together? There are just four forces in nature – electromagnetism, the strong and weak nuclear forces, and gravity. In fact it was shown, first theoretically, and later experimentally, that electromagnetism and the weak nuclear force are of the same origin.

As I mentioned briefly earlier, Peter’s PhD was about vibrations in molecules, a very different world from the world of particle physics in which he is now so famous. So how did studying one subject lead to a breakthrough in another?  The answer lies in a concept very important across the arts and sciences – symmetry. In fact in both domains it is not only symmetry but the breaking of symmetry that is important. Symmetry determines the vibrations of molecules, but symmetry is an essential concept across the whole of physics, including particle physics. Peter realised that the breaking of symmetry required a mechanism in which force-carrying particles acquire mass through interaction with another field. The field is now known as the Higgs field and the massive spin-less particle that carries it is known as the Higgs boson. The work is extremely important because it explains how the elementary particles of the Standard Model acquire their masses. Interestingly and not unusually in science, the publication of what is often called ‘the Higgs mechanism’ was rejected by the journal to which it was initially submitted. Also interestingly and not unusually in science, the Belgian team of Francois Englert and Robert Brout independently published similar ideas in the same year, 1964.

So why weren’t we celebrating this outstanding achievement 50 years ago? The answer is that it is a theory – an idea. It is an elegant theory that solves a serious problem in particle physics and is critical for the development of the electroweak model. It is a key part of the Standard Model of particle physics and so compelling that few scientists doubted it would turn out to be correct, but a theory needs experimental evidence. This evidence would come from observing the Higgs boson. How does one observe a particle? The answer is by building a machine called a particle accelerator in which particles are accelerated and then collided. The energy of the collision can lead to the generation of other particles. Particle accelerators are remarkable machines; they are the most complicated things that people have ever built, making spacecraft look simple in comparison. They accelerate particles extremely close to the fastest speed anything can travel at – the speed of light. The most powerful particle accelerator in the world is the large hadron collider at CERN, near Geneva, and over the past few years two enormous experiments called ATLAS and CMS, each consisting of teams of thousands of scientists, have searched for the Higgs boson. It is a fantastic example of international co-operation. The search was not without problems – the accelerator had a breakdown that took a year to repair. However, in 2011 they first found signs of the Higgs boson. With an announcement at a CERN seminar on 4 July last year, and with further analysis since, the evidence has become conclusive.

Peter was at a conference in Erice in Sicily the week before the CERN seminar and was planning to return directly to Edinburgh. As that week progressed speculation about a major announcement increased and culminated in a message from CERN that ‘Peter should come to the CERN seminar or he will regret it’. Travel plans were altered and the announcement by both the ATLAS and CMS teams that they had discovered a Higgs-like particle had the audience standing on their feet and cheering. Peter himself likened it to being at a local football match where the home team had won. Since then the data has been consolidated and it is no longer referred to as Higgs-like!

So the detection of the Higgs boson confirms the Higgs mechanism, which explains the mass of elementary particles such as quarks and electrons and weak nuclear-force carriers. The observation of the particle is a triumph of human achievement, involving thousands of people; the theory that inspired it is another triumph of human achievement attributable to Peter Higgs. These achievements are amongst the most important in science in the past fifty years, and are inspiring a new generation of scientists.

Vice-Chancellor, in recognition of his extraordinary contribution to physics, I invite you to confer on Professor Peter Higgs the Degree of Doctor of Science, honoris causa.