by A giant in particle physics, Peter Wade Higgs, died at his home in Edinburgh on 8 April 2024, after living for 94 years. His unparalleled legacy, exemplified by the discovery of the Higgs collar, continues to profoundly shape the future of particle physics like no other discovery before it. This is the story of his legacy.
When Higgs was born in 1929, our understanding of matter was completely different. Physicists had developed a simple model of matter with three fundamental, or fundamental, particles (those that cannot be broken down into smaller particles).
These were protons, which exist in the nuclei of atoms, electrons, which surround the protons and photons, packets of light responsible for the force of nature known as the electromagnetic force.
During Higgs’ lifetime, a great revolution would take place, and the Standard Model of particle physics would be created, the most successful framework for understanding the building blocks of the universe in history.
Higgs would provide the core of this theory. To understand the importance of Higgs’ work, it is necessary to understand the answer that nature laid out for the physicists, starting with the discovery of the neutron in 1932.
The neutron is a subatomic particle, a neutral partner of the proton, but slightly heavier. If ripped out of the atomic nucleus, a neutron decays into a proton and an electron in about ten minutes.
To explain this decay required a force and a new particle to mediate it (called a force carrier). The new force carrier had to be much heavier than both the neutron and the proton, which the general theory could not explain.
According to this theory, force carriers had to be massless. This was the case with the force carrier for the electromagnetic force, the photon. Physicists call this aspect of the theory symmetry.
In physics, theories with more symmetry have fewer free parameters – fewer parts of the theory that can be changed. An additional parameter, such as the mass of a force carrier, would make the theory inconsistent.
Physicists knew that some particles had mass, but they could not explain it. They had to find the right way to break or overcome the symmetry in this theory, giving the mass of the particles in a way that was compatible with everything known about the laws of nature. At the time Higgs began working on his ideas in the 1960s, the question of how elementary particles gained mass was a central issue in physics.
In the early 1960s, American physicist Phil Anderson noted that the problematic symmetry in this theory could be overcome in superconductors (materials that conduct electricity with zero resistance) or in charged gases called plasma. In the case of a theory that should explain mass, however, a viable solution could not depend on a particular medium or material.
Later, Higgs and other theorists developed a model that overcame this difficulty. The other physicists were Gerald Guralnik, Carl Hagen, Tom Kibble, Robert Brout and François Englert. Englert would share the 2013 Nobel Prize in Physics with Higgs.
The idea was simple and backwards in execution: a background field permeates the entire space, creating the kind of medium that Anderson’s idea worked for. Higgs published his first paper on the subject in 1964. In 1966, he was the first to predict that a “Higgs particle” must also accompany this “Higgs field”. If discovered, it would prove that the Standard Model was a consistent theory of nature.
But the search for the Higgs boson was extremely challenging. Higgs himself thought the question would not be settled in his lifetime. It took nearly 50 years and the largest experiment ever built, the Large Hadron Collider (LHC) at Cern, to finally discover the Higgs boson. On 4 July 2012, images of Higgs, moved to tears by the announcement, went around the world.
Our Universe is fundamentally shaped by the unique properties of the Higgs boson. Like the solid, liquid and gaseous states of matter, the Higgs field corresponds to the phase of the universe which can be determined by measuring the way the Higgs boson interacts with other particles.
In the decade since its discovery, the LHC has observed many of these interactions. These results raised new questions. The stability of the universe – its ability to continue in its current state forever – appears to depend on the mass and interactions of the Higgs boson.
If the current measurements of that particle are correct, the universe is not stable in its current state. This means that he may eventually undergo a transition to another form. The answers we find to this question may prove the Standard Model wrong.
Physicists also want to answer whether the Higgs field really explains all the masses of elementary particles as predicted by the Standard Model. For many Higgs bosons produced at the LHC, we can’t figure out what other particles they decay into. If we could, we could test more speculative theories related to dark matter or other theories outside the Standard Model.
To answer these questions, Europe, the US and China have proposed plans to build new particle colliders aimed at studying the Higgs boson. Higgs’ legacy is the experimental particle physics program of the 21st century.
Higgs was a physicist from another era. It would now be unthinkable for someone with his publishing record to be in academia. He published only a handful of papers, almost all of which were written by himself. Today’s academic culture creates intense competition and pressure to publish frequently.
Higgs admitted this in a 2013 interview: “It’s hard to imagine that in the current climate I’d have enough peace and quiet to do what I did in 1964… I wouldn’t get an academic job today… I think it would be considered me as a pretty productive person.”
This should be considered a warning. Time is needed to read and study works in other fields, such as the time Higgs spent to understand Anderson’s work. They require universities to create environments that prioritize time for research, rather than placing researchers in precarious positions dependent on the constant pursuit of grant funding.
It would be entirely appropriate if the legacy of Peter Higgs, who changed our understanding of particle physics, changed our approach to research.
This article from The Conversation is republished under a Creative Commons license. Read the original article.
Martin Bauer does not work for any company or organization that would benefit from this article, does not consult with, shares in a company or organization that would benefit from this article, and has not disclosed any material relationships beyond their appointment academic.
