In 2015, The Peter Higgs plaque was unveiled in Edinburgh to mark the achievements of the eminent physicist who was responsible for the discovery of the Higgs boson, an event hosted by the University of Edinburgh’s Vice Principal, Professor Richard Kenway. Professor Kenway called attention to the fact that the celebration of Peter Higgs, and the development of ‘such a seminal theory in physics’, took place ‘in the building where he first wrote it more than 50 years ago.’ The blue plaque is located at Roxburgh Street, sponsored by the Institute of Physics and Edinburgh City Council. Situated outside the flat where he predicted the existence of the Higgs boson in 1964, the plaque serves as the most recent addition to the ‘history of physics trail’ in Edinburgh, alongside the childhood home of Maxwell and the site of the Luckenbooths. All these physics-related landmarks are now listed on the Curious Edinburgh website. While the plaque summarises Higgs’ achievements, we will now explore, in further detail, his contributions to physics that earned him the Nobel Prize in Physics in 2013. 

The context of the Higgs hypothesis stems from the Standard Model (SM) of Particle Physics, a theory that describes the structure of the universe, explaining how forces and their carrier particles act on matter particles. The building blocks of matter are made up of elementary particles, quarks, and leptons, while the fundamental forces of the universe are mediated by their corresponding force-carrier particles, belonging to the broader group of bosons. For example, the ‘gluon’ carries the strong force, and the ‘photon’ carries electromagnetic force. The issue with the SM was that it could not explain why fundamental particles have a mass. Robert Brout, Francois Englert, and Peter Higgs resolved this problem by introducing the notion of a Higgs field, the Brout-Englert-Higgs mechanism, which gave mass to the W and Z bosons upon its interaction with them and had, like all other fundamental fields, a corresponding particle: the Higgs boson.  Straight after the big bang, the Higgs field was zero, but grew as the universe began to cool so that any particle that interacted with it acquired mass, whereas particles such as the photon did not and therefore have no mass.  

Higgs first moved to the University of Edinburgh as a Royal Commission for the Exhibition of 1851 Senior Student and as a Senior Research Fellow the following year, returning in 1960 where he took a lectureship in Mathematical Physics at the Tait Institute. By 1991, he was a Fellow of the Institute of Physics and became a Professor Emeritus in 1996. It was during this time that he began to work on a quantum field theory. His two papers completed in 1964 described the Higgs mechanism in which a field gave particles mass. He later revised the paper following its initial rejection to include his prediction of a boson. Allegedly, the idea of the Higgs mechanism sprung upon the physicist while he was walking in the wilderness of the Cairngorm Mountains in the Scottish Highlands; something that does not come as a surprise considering the many earlier physicists who had their own ‘eureka’ moments amongst nature – Elie Metchnikoff discovered phagocytosis on an Italian seaside, for example. Professor Higgs went as far as to state that: ‘If there is not a Higgs boson, the theory [the Standard model] does not make sense at all.’ It would take a powerful accelerator, one capable of creating energies equivalent to the temperature of the universe straight after the big bang, to validate his theory.  

All other predictions of the SM had been validated by experiments, with the discovery of the W and Z bosons at CERN and of quarks by the Stanford Linear Accelerator (SLAC). However, the Higgs boson remained undetected in the twentieth century due to the limitations of the Large Electron-Positron Collider (LEP), the accelerator initially used in the hunt for the boson. Nevertheless, by the early 2000s, most physicists believed that the discovery of the Higgs boson would be inevitable, and, around the same time, the Nobel committee had begun contemplating who should be awarded the prize for predicting it. There had been six physicists in 1964 who had independently published short papers proposing ways of giving elementary particles their mass. However, Higgs was notably the only physicist of the six to have explicitly predicted the existence of an actual particle.  

On 4 July 2012, the CMS and ATLAS experiments at the Large Hadron Collider (LHC) discovered a boson at 125 GeV (125 billion electron volts) which was consistent with the Higgs boson predictions. This formally confirmed the Higgs mechanism and, subsequently, Higgs and Belgian physicist Englert were awarded a joint Nobel Prize in 2013: 

“for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider.”

The Higgs boson can be rightfully described as a ‘Holy Grail’ of physics, for without it, the SM, which can be described as on par with Einstein’s theory of general relativity or Maxwell’s electromagnetism, would crumble as none of the fundamental particles in the universe would have any mass. The Peter Higgs plaque is therefore a signpost, a beacon, for the discovery of a mechanism that undeniably saved the Standard Model. He was awarded the Freedom of the City of Edinburgh in 2014 for his outstanding contributions. 

Written by Kat Jivkova 

Bibliography

Baggott, Jim. Higgs : The Invention and Discovery of the ‘God Particle’. Oxford: Oxford University Press, 2012. 

CERN. ‘The Higgs Boson’ [Online]. Accessed on 28 January 2021.  

home.cern/science/physics/higgs-boson  

Jenkins, Bill H. ‘Peter Higgs Plaque’ [Online]. Accessed on 28 January 2021. 

curiousedinburgh.org/2016/04/19/peter-higgs-plaque/  

Moffat, John W. Cracking the Particle Code of the Universe: The Hunt for the Higgs Boson. Oxford: Oxford University Press, 2013. 

The University of Edinburgh. ‘Peter Higgs: Curriculum Vitae.’ [Online]. Accessed on 28 January 2021. www.ph.ed.ac.uk/higgs/peter-higgs