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Professor explains how particle physics sheds light on models of the universe

| Wednesday, October 7, 2015

Tuesday night, associate professor of elementary particle physics Kevin Lannon gave the opening lecture to the new public talk series being put on by the department of physics entitled “Our Universe Revealed.”

In the series’s opening lecture, Lannon speculated about the potential future findings of the Large Hadron Collider (LHC) and the possible ramifications they may have for our understanding of the universe.

Lannon highlighted the central questions of the experiments being run by the LHC and other particle accelerators across the world.

“What is it that we are shooting for in the first place?” he said. “The question we are trying to answer is: what is everything made of?”

Lannon gave a brief history of the progression of human knowledge in the field of particle physics. He said the ancient Greek’s understanding of the universe was being composed of “uncuttable, indivisible building blocks,” purportedly a “finite number” of such.

He then went on to describe the findings of Dmitri Mendeleev who formed the early version of the periodic table.

The discovery of elements soon led to the discovery of protons, neutrons, and electrons.

“We had explained the whole universe in the terms of three basic constituents, and if we had just stopped there we would have a nice, simple picture of how the universe works,” he said.

“We were also aware that there were particles coming to us from outer space,” Lannon said. “And in looking, we found something that didn’t fit in the picture — there was an extra particle.”

That extra particle was the muon, he said, and its discovery soon led scientists to begin the practice of colliding particles. By the time the 1950s came around, Lannon said there was “a whole zoo of particles.”

There were dozens of fundamental particles, but scientists spent some time thinking about the properties and were able to make an arrangement, Lannon said.

“Along the way, we picked up the photon and neutrinos,” he said.

With the overwhelming number of particles present, Lannon said scientists were eager to organize their discoveries.

“We have this drive to find patterns,” he said.

In the 1960s, that drive led scientists to divide the particles into three categories — quartz, lepton and photon.

After this, scientists knew that there were four forces in the universe, and they theorized that there must be a particle for each force.

They discovered that it was more plausible for there to be six types of quartz and six types of lepton particles. However, Lannon said “the theory only works if the particles don’t have mass.”

That seemingly perplexing idea was the origin of the search for the Higgs Boson particle — the particle that could explain this phenomenon, Lannon said.

“As of the mid 1970s, there are particles that we hadn’t discovered yet,” Lannon said.

Gradually more and more of the theorized particles were discovered; on July 4, 2012, the Higgs Boson particle was found.

Lannon concluded the talk by comparing the continued search for the answers to these complex questions related to particle physics to attempting to solve a puzzle.

“This puzzle could have a pretty exciting conclusion,” Lannon said. “Unlike the puzzles you may be used to, there isn’t a box top with a picture of what the puzzle is supposed to look like when you’re finished.”


About Eddie Damstra

Eddie is a senior from Orland Park, Illinois. He is majoring in Economics and Political Science with a minor in Constitutional Studies and plans on pursuing law school after his time as an undergraduate at the University of Notre Dame.

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