The Royal Society of Edinburgh Inspiring Brilliance: Celebrating Maxwell’s Genius and Legacy on the 150th Anniversary of the Publication of Maxwell’s Equations Supported by: The James Clerk Maxwell Foundation; The University of Edinburgh; The Institute of Physics; IEEE Monday 9 November 2015 Report by Peter Barr James Clerk Maxwell: The story continues “Inspiring Brilliance” brought together some of the most distinguished scientists in the UK to celebrate the genius and the legacy of one of the world's greatest physicists, considered the equal of Newton and Einstein, whose achievements are only beginning to get the public recognition they deserve... It's almost unbelievable that one man could have such an impact on so many different areas of science and technology: digital communications, colour photography and cybernetics; mathematics, structural mechanics and astronomy; statistical physics and particle physics; relativity and quantum theory. And his influence not only continues 150 years after he published his ground-breaking theories, but promises to carry on into the future. The man who “did it all” was a scientist from Scotland called James Clerk Maxwell, born in Edinburgh in 1831. And he first came to public attention when James Forbes, the Professor of Natural Philosophy at the University of Edinburgh, presented the young teenager's paper On the description of Oval Curves and those having a plurality of Foci at the Royal Society of Edinburgh (RSE) in 1845. At the RSE 170 years later, an audience was treated to a day of presentations which reviewed the key achievements of Maxwell's career and his continuing impact on science and technology, as well as focusing on some of his less famous achievements – for example, he devised a foolproof method of measuring the precise length of a yard, and he wrote poetry in his spare time. RSE President Professor Dame Jocelyn Bell Burnell welcomed the audience and not only drew attention to the 43 poems by Maxwell, but also cleared up all confusion regarding his name – he had been born James Clerk but gained the name Maxwell when his father added it in order to inherit a family estate. So, strictly speaking, Maxwell should be known as Clerk Maxwell. The Chairman of the James Clerk Maxwell Foundation, David Forfar, introduced the presentations on Maxwell by quoting the Nobel-prize-winning physicist Richard Feynman: “Ten thousand years from now, there can be little doubt that the most significant event of the 19th Century will be judged as Maxwell's discovery of the laws of electrodynamics. The 1 American Civil War will pale into provincial insignificance in comparison with this important scientific event of the same decade.” Forfar also described Maxwell's close connections with the RSE, beginning with his paper of 1845 (at age 14) and two subsequent papers, before he even entered University. He became a Fellow of the RSE at the age of 24 and twelve other family members were Fellows of the RSE or of the Royal Society, or both. And when Maxwell was interviewed at Trinity College in Cambridge in 1850, he was able to quote these three RSE papers as examples of his work. All the speakers focused on Maxwell's huge impact, spanning three centuries – and promising much more to come. Emeritus Professor Peter Higgs revealed that the work of the Large Hadron Collider at CERN may be on the verge of some earth-shattering discoveries, including dark matter, with Maxwell's theories still a significant factor in the latest research. Professor Harald Haas did a world's-first demonstration, transmitting large amounts of encoded video data at very high speed via red, green and blue LED lights, using “a modern version of Maxwell's light box which will soon be inside every smartphone.” In other words, new chapters in the Clerk Maxwell story continue to open; not just in fundamental science, but in everyday technology. 1. Maxwell’s Equations: The Tip of an Iceberg Professor Peter Higgs CH FRS FRSE – Nobel Laureate; Emeritus Professor of Theoretical Physics, University of Edinburgh “I'll try to tell the story of Maxwell's equations, and how they are only the tip of an iceberg,” Professor Higgs began, before he traced the influence of Maxwell on the history of physics. He described various attempts to progress towards a unified theory of all forces – a “theory of everything” – in the midst of which Maxwell's equations continue to play a key role. Maxwell's theory of electromagnetic fields was the “first fully-fledged field theory of forces” said Higgs. Faraday had talked about electric and magnetic fields before, but Maxwell advanced this and came up with the first classical field theory of electromagnetism. Maxwell was still basically “Newtonian” and lived at a time when many scientists still believed in the “luminiferous aether” – the idea of a medium through which light could travel – and many believed that light was made of subtle particles. Maxwell then came up with his theory that light was composed of electromagnetic waves. The failure of experiments to find the aether was used by Einstein to develop his special theory of relativity in 1905. Forty years after Maxwell’s electromagnetism, Einstein resurrected the particle, or corpuscular, theory of light and modified Newton's ideas, leaving Maxwell's theories intact. When Einstein developed his theory of general relativity in 1915, he did so “with the knowledge of what went before him,” including Maxwell's work on electromagnetism. Quantum mechanics and the development of quantum electrodynamics owe a large debt to Maxwell's equations, said Higgs, and Maxwell’s influence on physics continued throughout the 20th Century. Higgs discussed the “problems of infinities” which accompanied the emergence of quantum field theory, which incorporated generalisations of Maxwell's equations. The next development, said Higgs, was the connection between two major concepts in physics – symmetries and conservation. And as physicists wrestled with various theories over the decades, asking “what to do with symmetry?” and describing complex topics such as wave equations of charged particles in electromagnetic fields, Maxwell's theories always had a central role to play. 2 “During the course of the 20th Century,” Higgs continued, “it became clear that the forces of electromagnetism and gravity were not the whole story.” Theories were developed to take account of nuclear beta decay and radioactivity, and new ideas emerged describing phenomena such as the “weak nuclear force.” Rutherford also did important work on the atomic nucleus, while other new theories suggested that there must be a “strong force” to hold the nucleus together. In 1932, ideas such as “isotopic spin” appeared. “The story of elementary particles involves the discovery of bigger and bigger apparent symmetries, associated with ‘charge’ conservation,” said Higgs. But the theory of strong nuclear force “didn't work too well” when you tried to understand neutrons and protons. And the theory of weak force was “even worse.” It was clear there were similarities between weak force and electromagnetic force, but if there was, said Higgs, “the particles that carry the weak force would have to be massive.” When you try to handle the quantum theory involving massive force-carriers, he continued, you get “nonsense” and it is a “disaster for the theory.” In the midst of these struggles, it was “easy to generalise Maxwell's equations to higher symmetries.” Fields now interacted with themselves, but massless particles were “another non-starter,” said Higgs. Then in 1960, quantum theory “smashed the theory” of superconductivity and the spontaneous breaking of symmetry – physicists assumed that a vacuum would be symmetric, said Higgs, but this was not the case. The appearance of “massless, spin-less particles was a disaster,” he said, “because there aren't any.” Fifty years ago, said Higgs, physicists found a way out of this “difficulty,” and Maxwell-type fields helped them develop new theories. All that had to be done was “marry spontaneous symmetry with Maxwell field theory,” to produce a theory that was later proved to be experimentally correct, followed by other “viable” theories such as quantum chromodynamics, in which “nothing was swept under the carpet,” he added. We now know that “neutrons and protons are not elementary particles,” said Higgs, “but are made of quarks.” And Maxwell-type fields have continued to play a big role in the development of particle physics. “Maxwell has spawned a lot of progeny,” Higgs concluded. Q: When can we expect the unification of general relativity theory? Will it be when “Maxwell marries Einstein”? A: There is a class of theories that can't handle the inherent infinities. In the 1970s, there was a promising theory of super-symmetry, predicting that the elementary particles (of the Standard Model) would each have a super-symmetric partner. This idea could solve some of the problems of uniting the field theories of some of the forces. Super-symmetry in turn triggered the development of string theory and super-string theory, avoiding some of these difficulties in quantum field theory, but the timescale for a fully successfully unification of all forces (including gravity) is another question. Q: What will we discover when CERN (the Large Hadron Collider) is boosted? A: CERN is now running at close to the design energy (of 14 TeV). The discoveries three years ago were at half the design energy. It maybe that types of super-symmetric particles will be found, including candidate particles for dark matter – which makes up 90 per cent of the Universe. There may of course be some surprises – things we did not expect. There will also be more detailed measurements, to help us understand things found three years ago. Q: How heavy will these particles be? A: Theories predict some of these super-symmetric particles will be much lighter than others.