Particle discovered 50 years after its prediction

Weekender

By THOMAS HUKAHU
AS you may have been following my articles in past weeks, I have been sharing with you discussions about concepts in physics, philosophy and theories which are proposed by all sorts of people, some sensible while others are debatable.
I want to end this series of articles with an interesting discovery in physics exactly eight years ago.
The discovery further illustrates how scientists, like physicists, work with theories they propose.

Theories proposed then
verified
In physics, as in other hard sciences, often a theory can be proposed about something, or a prediction of something is made and years later a discovery is made that verifies the theory or confirms the prediction.
Mathematician and astronomer John Couch Adams predicted the existence and position of the planet Neptune by using mathematics, and nothing else.
He noted that orbit of Uranus, the planet before Neptune, was not altogether following the laws of planetary motion as devised by Johannes Kepler and Isaac Newton.
At about the same time, French astronomer and mathematician Urbain Le Verrier was doing the same kind of calculations and sending his prediction and position to an astronomer in an observatory who trained his telescope to that part of the sky and located the planet in 1846.
Clyde Tombaugh discovered Pluto in 1930 in a similar fashion. Many astronomers theorised that there was an object out there to explain the weird observations of the orbits of Uranus and Neptune.
Such is the wonder of physics and other hard sciences. Often, predictions of bodies or particles are made before their eventual discovery.
That is usually not the case with other fields where certain theories are proposed but there is no empirical evidence to validate such ideas.

Special day in 2012
Good scientists possess a special ability to “see” and they predict things. That is a physical ability and with good training it is developed.
On July 4, 2012, physicists everywhere became excited when those at the European Organisation for Nuclear Research (CERN) observed a new sub-atomic particle, a boson.
High school science teaches that in an atom there are sub-atomic particles like the lighter, negatively-charged electrons, positively-charged protons and neutrons that do not possess a charge. The protons and neutrons are the heavier particles and are in the nucleus of an atom.
In reality, the elementary particles are quarks, leptons and bosons. The electron is a lepton, while the proton and neutron are combinations of some elementary particles.
The prediction of the existence of a special boson was made by English theoretical physicist Peter Higgs (and others) in 1964. In 2012, about 50 years later, that particle was observed.
So how is it that they could predict the existence of something that others could not? That comes from their scientific training and being inquisitive about data – from experiments or theories from other scientists.
A good quote I took note of many years ago is: “The unprepared eye does not see.”
That is a quote by physicist Emilio G Segrè in his book From X-rays to Quarks: Modern Physicists and Their Discoveries.
All of physics can be categorised as experimental or theoretical physics. Theoretical physicists come up with the theories (and can make predictions) that experimental physicists try to test.
Albert Einstein was a theoretical physicist and when he first came up with the idea that energy and matter can interact, he was snubbed.
That is basically what is described by his famous equation which relates energy to matter. This idea was part of his general theory of relativity and was put forward in 1911. On May 29, 1919, astronomers observed a solar eclipse in Africa.
They knew, if Einstein was correct, stars “at the back” of the sun should be seen because their light would be attracted and bent by the sun’s gravity as they passed by it.
Their observation confirmed what Einstein’s theory predicted, the news spread and Einstein was hailed a genius. Yes, he saw things that others did not see.

What is this Higgs boson?
I will try to be brief in my description of what this Higgs boson is and how it fits into the existing body of physics laws.
Firstly, let me also clarify what this Higgs boson is.
As stated earlier, protons and neutrons and electrons were taught to high school students as fundamental particles. That however is not true.
The fundamental particles are quarks, leptons and bosons. Some of these particles have mass while some are massless, like photons which are “particles of light”.
The Higgs boson has mass while another boson, the photon, is massless. In trying to explain how particles move through space and around us, the concept of Higgs boson and a Higgs field were theorised by physicists like Higgs.
The Higgs particle tries to explain why some particles have mass, while others do not.
A channel on YouTube named SciShow explains it in a video titled So what is this Higgs boson?
It states that Higgs particles are distributed evenly throughout the universe. It is these particles that give the Higgs field (in that same way that gravity or a gravitational field is produced by matter and is more noticeable near massive bodies like stars or planets).
Photons, which are actually light, while travelling through space do not interact with the Higgs field. Electrons interact weakly with that field while some quarks, which are heavier than the electron, interact heavily with the Higgs field.
This may not sound so novel or mind-blowing, but that is the simple description and tries to explain why some particles have mass while others do not.

Challenges ahead for physicists
There is another interesting YouTube video that gives more information on the Higgs boson and what challenges are out there for physicists, both the theorists and the experimentalists.
In the World Science Festival on April 11 this year, a group of physicists, mostly particle physicists, discussed the challenges ahead for physicists.
The moderator for that discussion was physicist and mathematician Brian Greene and the panel included physicists Nima Arkani-Hamed of Princeton, Monica Dunford of CERN and Joseph Lykken of the Fermi National Accelerator Laboratory.
Dunford has been with CERN for more than a decade and was there in 2012 with the team that discovered Higgs boson.
Arkani-Hamed makes an important point in saying the Higgs boson and the other particles in the group of Standard Model Particles are governed by the principles of relativity and quantum mechanics, two of the basic principles that describe almost everything that is observed in the universe.
Dunford says that the team at CERN that discovered Higgs boson was a collaboration between many countries and about 3000 people were involved.
She says the large hadron collider (LHC) was an accelerator that had a tunnel that was 27km long and took 15 years to build.
At the moment, the LHC in Switzerland is the largest accelerator but there is a plan to build a bigger one that would run along a distance of 100km.
Dunform says that a Higgs particle is produced in the LHC by bombarding two fast-moving protons. But the Higgs particle exists for a very short time and then it decays into other particles like quarks or photons.
She says the bigger the accelerator and energy used, the bigger the collision will be.
She says it is the studying of the products of a Higgs boson’s decay that enables the scientists to verify the existence of the boson.
Lykken states that when Higgs first proposed the idea of the Higgs boson in a scientific paper, his theory was rejected. But that did not stop him from lecturing on it.
Now, 50 years later, the particle he had predicted has been found.

Where is Peter Higgs today?
The man after whom the boson was named, Peter Higgs, is a retired professor and has been with the University of Edinburgh for many years.
As soon as the boson was verified, the late Stephen Hawking suggested that the next Nobel Prize in Physics should be awarded to Higgs.
In 2013, that prestigious award was awarded to Higgs and Belgian physicist François Englert for the discovery of the Brout-Englert-Higgs mechanism.
Higgs is 91 years old today.
In the video mentioned, there is a clip where Higgs responded emotionally to the announcement of the discovery of the particle that bears his name.

Next article: True marriage and wrong marriage.

  • Thomas Hukahu is an Australia Awards students living in Adelaide.

Note: We have been advised that the above article incorrectly states that particle physicist Nima Arkani-Hamed is affiliated with Princeton University. Professor Arkani-Hamed is on the faculty of the Institute for Advanced Study, located in Princeton, NJ but unaffiliated with Princeton University. – Editor.

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