Cobra Effect · Particles
The particle that revealed a hidden field
How a 1964 prediction about mass was confirmed at CERN in 2012.
7 cards, read aloud in 3:06, with a test and sources.
In the early 1960s, physicists faced a puzzle about mass.
Their most promising theories of the forces worked neatly only for particles with no mass. But the particles that carry the weak force, which drives some radioactivity, had to be heavy. Simply adding mass by hand wrecked the mathematics.
In 1964, three separate papers proposed the same kind of answer.
They came from Francois Englert and Robert Brout in Brussels, Peter Higgs in Edinburgh, and Gerald Guralnik, C. Richard Hagen and Tom Kibble in London. They suggested that space is filled with an invisible field. Particles that interact with the field gain mass. The more strongly they interact, the heavier they are. Higgs drew attention to a particle that the field should also produce.
Finding that particle would take nearly fifty years.
The theory did not say exactly how heavy it would be. Making one would take enormous energy, and it would break apart almost instantly. Physicists would have to recognise it from the particles it broke into.
At CERN, the Large Hadron Collider smashed protons together at enormous energies.
Its tunnel runs in a ring twenty seven kilometres around, beneath the border of France and Switzerland. Two giant detectors, called ATLAS and CMS, each with about three thousand scientists, searched separately. They looked for a small excess of the right kinds of collisions, among vast numbers of others.
In July 2012, both teams announced a new particle.
It was more than a hundred times as heavy as a proton. Each team had found it independently, at the high level of confidence physicists demand for a discovery. CERN said the particle was consistent with the long sought Higgs boson. Peter Higgs and Francois Englert were both in the audience.
By March 2013, more data showed that it was a Higgs boson.
That October, Englert and Higgs were awarded the Nobel Prize in Physics. Robert Brout had died in 2011, and the prize is not given after death. The field gives mass to fundamental particles, such as electrons and quarks. Most of the mass of everyday things comes from elsewhere, from the energy that binds quarks inside protons and neutrons.
So when a theory predicts something no one has seen, ask what it would take to find it.
The Higgs boson was predicted in a few pages of mathematics. Finding it took decades, thousands of people and one of the largest machines ever built. A prediction only becomes knowledge when someone does the work to test it.
Sources
- The Nobel Prize in Physics 2013, popular information, NobelPrize.org. A clear explanation of the Higgs field and the 2012 discovery.
- The Higgs boson, CERN. What the Higgs boson is and how CERN found it.
- 1964 PRL symmetry breaking papers, Wikipedia. The three 1964 papers and who wrote what.
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