How Peter Higgs revealed the forces that hold the universe together

Peter Higgs led an unusual life. He developed physical theories that had the potential to radically advance our understanding of the universe, and generations of experimentalists followed his work and ultimately embraced his laboratory work. I witnessed it live. He died at the age of 94 at his home.

“Without the Higgs work, we wouldn’t understand why atoms exist. We wouldn’t understand some pretty fundamental features of our world,” he says. John Ellis At King’s College London.

Higgs began his research in the 1960s at the University of Edinburgh, UK. He was thinking about an area of ​​physics called quantum field theory, and spent about a week writing a short paper on the subject in July 1964. physics letters accepted the study, but rejected a more detailed follow-up study of Higgs after only a week.nevertheless physical review letter Although he eventually published a revised version of his second paper, it did not create much fanfare and remained ignored for many years.

Ironically, these papers contained a key element that was largely missing from the theory of all particles in the universe: why particles have mass.

Almost all known particles require some amount of mass in order to bond with each other to form the atomic-like structures that make up our physical world. But physicists understand every particle to be an excitation of an invisible field that permeates everything. For example, an electron is an excitation of an electromagnetic field. Even the best theories of the time could not explain where these masses came from.

Higgs theorized that particles gain mass by interacting with new types of fields. There was another particle in the field, a very special excitation of its own, called the Higgs boson. The Higgs field solves big problems in particle theory, and the Higgs boson has been an attractive target sought by experimentalists to connect theory and reality.

“If you remove everything from the vacuum, all matter and quantum fluctuations, all electromagnetic matter, all gravity, you’re left with the Higgs field,” he says. frank close at Oxford University. “We need it just like goldfish need water. It stabilizes empty spaces.”

Belgian physicists François Unglert and Robert Braut also worked independently of Higgs and reached the same conclusion in 1964.

But Higgs wasn’t necessarily trying to write a groundbreaking paper, said Close, who wrote a 2022 biography of Higgs. He was simply following a rigorous and often lonely academic stream, which resulted in him becoming deeply concerned about what appeared to be the technical problems plaguing quantum field theory. Other physicists had previously solved similar problems in systems with fewer cosmological effects, such as perfect conductors of electricity. Higgs figured out how to generalize their mathematics to all of particle physics.

But quantum field theory was out of fashion at the time, and when Higgs lectured about his work at prestigious institutions like Harvard University in 1965, he was met with mostly skepticism, Ellis said. he says. In 1976, Ellis and two of his colleagues at his CERN particle physics laboratory in Geneva, Switzerland, wrote a paper Several experiments at the facility have focused attention on how the Higgs boson appears.

“No one seemed to care, but for us, [the Higgs boson] It was very important…and I was absolutely convinced that the Higgs boson would be discovered. ” Dimitri Nanopoulos from Texas A&M University is a co-author on the paper. Although he was a very young researcher at the time, his research foresaw the future of particle physics. By 1984, physicists’ views had changed and they were eager to search for the Higgs boson. CERN leaders discussed building a new particle collider, primarily to aid in exploration.

Its detector, the Large Hadron Collider (LHC), discovered the Higgs boson in 2012. Inside the LHC, researchers carefully designed a head-on collision of two incredibly fast protons, a collision that could produce the Higgs boson. But the boson lasts less than a billionth of a second before becoming a shower of other particles. Analysis of the debris from the collision showed with very high certainty that these particles came from the Higgs boson, giving only a 5 in 10 million chance that they were a fluke.

Physicists around the world were overjoyed, and the following year Higgs and Englert shared the Nobel Prize in Physics.

Mr. Close and Mr. Ellis said that even before the LHC began operating, other collider systems had not yet directly justified the Higgs theory, such as very accurate measurements of the masses of other exotic particles. He said he had obtained the evidence. Higgs was aware of these findings, as he explained: new scientist In 2012, he said, “I believed in the theory behind that mechanism because other features of it had been examined in great detail in successive collision experiments.” It would have been very surprising if it wasn’t there.”

Still, the direct search for the Higgs boson at the LHC had a strong impact on particle physics. It stepped up efforts to build new infrastructure, such as accelerators, and strengthened large-scale collaborations to manage this equipment as a standard approach to conducting scientific research.

Since 2012, the LHC has been modified to produce even higher-energy collisions, allowing researchers to study not only particles, including the Higgs boson itself, but also dark energy and dark matter, a largely unexplained phenomenon. We are working to answer the remaining questions. of the universe.

Higgs himself was interested in some of these questions and continued his research after retiring in 1996. “And it deepens his understanding of the connections between particle physics and what happened in the early universe,” he said. new scientist In 2013.

Nanopoulos says the discovery of the Higgs boson is the end of a chapter, but not the entire book.

Even after retiring, Higgs continued to engage in original research. He was particularly interested in supersymmetry. Supersymmetry is a theory that assumes the existence of a heavy particle that corresponds to every particle already detected. Physicists who share this interest and want to find experimental traces of it expect the LHC to discover dozens of new particles.

In addition to the Nobel Prize, Higgs received several awards, including the Paul Dirac Prize, the Wolff Prize in Physics, and the American Physical Society JJ Sakurai Prize. In 1999, he declined his knighthood, a fitting rejection of his public reputation. He didn’t want the title, was embarrassed by the media attention his research had attracted over the years, and particularly disliked the Higgs boson’s sensational nickname, the “God Particle.”

The story of how Higgs tried to avoid the call from the Royal Swedish Academy of Sciences informing him that he had won the Nobel Prize by leaving home without a mobile phone is well known among physicists. Ellis also recalls that Higgs initially declined his invitation to come to CERN to officially announce the discovery of his eponymous particle. However, his colleagues eventually convinced him to join the festivities.

Close titled his biography of Higgs “Elusive” and states that it describes both Higgs and Higgs. Physicists widely agree that he is a unique person and respect him for that.

Mr Higgs died at his home in Edinburgh on April 8th after a short illness. He left behind his two sons, a reinvigorated field of physicists exploring elementary particles, and a clearer understanding of the forces that hold the universe together.