How physics explores the world’s unanswered questions

7 Jul 2021

Image: Sinéad Ryan

Trinity College Dublin’s Sinéad Ryan discusses her work in theoretical physics, the value of a CERN membership for Ireland, and what the future could hold.

The past 18 months have unsurprisingly put a major spotlight on research and innovation in the areas of pharma, health and vaccinations.

With the Covid-19 pandemic sweeping the globe, the world has been watching everything from the first encouraging responses in early vaccine trials to the science behind mRNA technology and the challenge of cold supply chains.

But while pharma companies and biotech researchers continue to work hard in these areas, other sections of science are enjoying their own breakthroughs.

Particle physics is about trying to understand the nature and structure of matter in the universe and how the simplest building blocks respond and interact with the four known fundamental forces.

Earlier this year, physics researchers experienced their “Mars rover landing moment” when new evidence suggested the existence of a fifth force of nature.

The findings came from physicists at Fermilab, the US Department of Energy Office’s national laboratory.

Sinéad Ryan, now a professor of theoretical high-energy physics at Trinity College Dublin, worked as a postdoctoral researcher at Fermilab in 1999.

“It was a fantastic moment to join the lab, which at the time was the highest-energy particle collider in the world and so a centre of research and collaboration – and a must-visit for all high-energy physicists.”

‘In the near future we will see a step-change in computing power as so-called exascale computing becomes a reality’

When Ryan first joined the theory group at Fermilab, she started to work on calculations that are crucial for constraining parameters of the standard model of particle physics – the theory that explains how the basic building blocks of matter interact, governed by four fundamental forces.

“These calculations were done using large-scale numerical simulations, a field of research called lattice QCD, and resulted in some of the most precise results available at the time and the development of some new methods that are still in use today, although the same calculations are now far more precise.”

Ryan said within physics there are so many open questions, some related to known physics such as the fundamental forces and others related to physics beyond the standard model such as dark matter.

“Theory and experiment complement each other as we try to answer these and other questions. At times theoretical predictions motivate experimental searches – the Higgs boson is a nice example – and at other times it is an unexpected experimental discovery that motivates theorists to explain fully what is going on.”

Ireland and CERN

Ryan said the interplay between theory and experiment is crucial to driving progress in physics and CERN, the European Organisation for Nuclear Research, is a vital part of that progress for the science community.

“CERN in Geneva is the world’s leading particle physics laboratory and delivering that science means it is in essence the largest engineering and IT project on the planet,” she said.

“Ireland is one of the very few countries in Europe to have no association with CERN. As a result, Irish research, education and industry has limited access to the enormous benefits that membership grants.”

In November 2019, an Oireachtas Committee on Business, Enterprise and Innovation recommended immediate plans for CERN membership, a move that is supported by the Ireland-CERN users group.

The future of physics

While she has worked in quantum field theory since her PhD days, Ryan said the nature of particle physics means a lot of questions remain unanswered, which leaves a lot to be excited about when it comes to what the future holds.

Her own interest is in the unexpected discovery of exotic states of matter, formed primarily from charm and bottom quarks interacting under the strong interaction in novel configurations.

“I am also trying to understand what happens to matter at temperatures of billions (or trillions) of Kelvin – the conditions in the early universe, fractions of a second after the Big Bang.”

Lattice QCD, the field of research focused on numerical simulations that Ryan worked on at Fermilab back in the late ’90s, has now been at the forefront of high-performance computing for more than three decades.

Ryan still works in lattice QCD and her work has been enabled by computing time awarded on some of the world’s fastest supercomputers.

“We are preparing now for the next-generation exascale machines and a recent Academic Flagship award from ICHEC means that, with collaborators, we have support to optimise and run codes on these new machines,” she said.

“In the near future we will see a step-change in computing power as so-called exascale computing becomes a reality. Everything from understanding and modelling climate change and searches for new materials, to personalised medicine and fundamental questions in astro and particle physics will be revolutionised.

“Europe will soon have its own exascale computers, matching or exceeding those in the US, China and Japan.”

Physics misconceptions

As with a lot of science disciplines, Ryan said the stereotypical image of what a physicist looks like is a common misconception, with white men often springing to mind.

“There are all sorts of shapes and sizes and we are as different in outlook, opinions and appearance as any group,” she added.

“It is still the case, however, that diversity and gender balance are far from solved problems. Within my own field – lattice QCD – the community has elected a diversity and inclusivity committee of which I am a member and we are working to understand barriers faced by underrepresented groups, or anyone, in conference participation and in day-to-day work.

“In many cases in physics and mathematics, the gender imbalance begins in undergraduate degrees and not surprisingly doesn’t improve with career progression. Although many, but not all, structural barriers have come down, I think the fantastically broad and rewarding career path that opens up with a degree in physical sciences and mathematics is still not widely appreciated.”

And while health and pharma research has made headlines over the past year, physics has also played a role during the pandemic, Ryan noted.

“In the last year there has, quite rightly and understandably, been a huge focus on science related to Covid and I strongly believe that what we have seen is the huge potential impact of science for the betterment of our lives,” she said.

“What is sometimes not so obvious in the last year has been the role of numerical simulation, eg in understanding the structure of the SARS-CoV-2 virus and in modelling airflow and understanding airborne transmission.”

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Jenny Darmody is the editor of Silicon Republic