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Particle physics

Huge computer simulation will show us how elementary particles dance with each other

The elementary particles are the smallest building blocks we know. The way they interact with each other is crucial to how you, your dog, the Earth and everything else in the universe is created. Now a gigantic computer simulation will take a snapshot of elementary particles dancing with each other.

By Birgitte Svennevig, , 9/29/2023

The principle of what exists in the universe and under your fingernail is the same: all matter is built of elementary particles. Science knows (so far) 12 matter particles, and in addition a number of force carriers. These particles all relate to and interact with each other in a myriad of different ways.

How this happens will now be investigated by particle physicist Antonio Rago, Department of Mathematics and Computer Science, in a gigantic computer simulation. From The European Council, he has been granted 120 million core hours on the European supercomputer LUMI, located in Finland. For comparison, Denmark, being part of the consortium behind LUMI has a share of 87 million core hours per year for all the country’s scientific institutions.

With the 120 million core hours, Antonio Rago can set LUMI to work for approx. three months. In those three months, the supercomputer can calculate as much as it would take an ordinary laptop 1,712 years to work through.

What is an elementary particle? 

An elementary particle is a particle that cannot be divided into smaller parts. It was once thought that the atom was the smallest elementary particle, but in 1897, the British physicist, J. J. Thomson showed that the atom consists of even smaller elementary particles. The elementary particles are either matter particles (6 quarks and 6 leptons) or one of the five force carriers (eg light particles mediating the electromagnetic interaction and gluons that hold quarks together).

The goal of the computer simulation is to create what Rago calls a snapshot of a small piece of the universe. To be precise, he wants to create an extremely detailed simulation of a hypercube of space and time with the measurements of 12 x 12 x 12 x 12 femtometers. A femtometer is one quadrillionth of a meter, so it's a very, very small cube. The amount of time will be 40 septillionth of a second (1 septillion is 1 followed by 24 zeroes).

One must not forget though, that there is a lot going on in the tiny box: Here, elementary particles will unfold and show how they behave together with others. There is an extreme difference in the size of elementary particles, and level of details, that the simulation must take into account: The resolution needed corresponds to being able to see both the details of Mona Lisa's nostrils and the entire mountain Mont Blanc in the same picture.

Antonio Rago hopes that the simulation can contribute with input to a number of particle physics' puzzles, including:

1. Are there elementary particles or interactions that we do not yet know about? By comparing his simulations with the results obtained from experiments, he will be able to identify tensions and discrepancies that can only be explained by the existence of new particles.

2. Why is there more matter than antimatter in the universe? We know that there is an antiparticle for every particle of matter, so it is difficult to explain why there are more matter particles than antimatter particles in the universe. But there is: for every billion antimatter particles formed during the birth of the universe, one billion and one matter particles were formed.

Basic research has changed the world

Exploration of the universe and the physical laws that apply in the interaction between elementary particles is, at first sight, basic research because it is driven by curiosity and does not in itself have a concrete, practical problem to solve.

- But it is precisely from this field that some of humanity's great inventions come. These are inventions that we had no idea were possible before science started exploring physics, says Antonio Rago.

We can e.g. thank Einstein's curiosity for his formulation of the theory of relativity. Without it, GPS systems would not be accurate, because the theory of relativity takes into account that both the strength of gravity and the speed between two objects affect how time passes.

We can also thank the physicists at CERN (European Center for Nuclear Research in Switzerland) for the Internet: it was originally developed as a tool to make it easier for physicists to find and sort colossal amounts of data.

- There may be more world-changing inventions from physics: Perhaps physicists will one day succeed with nuclear fusion and mimic the fusion of the Sun's nuclear core, thus producing lots of energy that leaves no radioactive waste, says Rago.

Meet the researcher

Antonio Rago is a particle physicist and associate professor at the Department of Mathematics and Computer Science.

Go to profile

The supercomputer LUMI

LUMI is a European supercomputer located in Finland. The countries in the consortium behind it are Belgium, Denmark, Estonia, Finland, Iceland, Norway, Poland, Switzerland, Sweden and the Czech Republic.

Visit LUMI

Editing was completed: 29.09.2023