What’s the point of particle physics?

What’s the point of particle physics?

Particle physics makes up a large component of the IB course for physics, and it can often be a source of equal parts fascination and frustration for students. The fascination comes from the fact that this can be a completely new part of the course that many students are seeing for the first time. The problem is that because there are essentially so many rules to learn to be able to access the course, it can become frustrating to learn.

Playing a game

The best way I can describe learning particle physics is like learning the rules of a game. You need to know what each piece does, but also how they are permitted to move and interact. To that end, please indulge this nerd as we breakdown the particles overall.

A breakdown of the Standard Model of particles, also known as The Particle Zoo. Image Credit – R Wrigley

In the most basic of terms, particles can be broken down into Quarks and Leptons, and you cannot get any smaller. Quarks can combine to make other particles (protons, and neutrons for example), leptons cannot make up other particles.

Once we know the pieces, physicists have to understand the rules for how these pieces move. If there is sufficient energy to do so, particles can decay (a fancy way to say change) into other particles, we can have particles combine to create other particles.  The rules that govern these interactions are basically, do we have the same amount of things before and after a decay. We need to have the same number of Baryons and leptons before and after, as well as the same amount of overall electric charge.  There are a few other quantities that also need to be conserved, but these are the basics.  For example, if a proton collided with another proton, it could not produce two protons and a neutron. Why? Even though the total charge is conserved, and we have the same amount of leptons before and after, we have created an extra baryon, so the baryon number is not conserved.

A visual explanation of conservation rules. Image credit – R Wrigley

So what is the point of all this, and why are we learning all of this? I get this question a lot, and it is also something that I asked myself when I was seventeen and seeing this for the first time. My first answer is that we are looking at the nature of matter and therefore the nature of the universe itself, isn’t that kind of cool? The best way I can describe how bonkers and awesome particle physics is a quote from renowned physicist Richard Feynman:

“I hope you’ll come along with me, and you’ll have to accept it, because it’s the way nature works. If you want to know the way nature works… We looked at it, carefully… That’s the way it looks! You don’t like it? Go somewhere else… to another universe where the rules are simpler, philosophically more pleasing, more psychologically easy.” (Feynman, Lecture 1. “Photons: Corpuscles of Light” (1979) Sir Douglas Robb Memorial Lectures, University of Auckland.)

Nice quotes from Feynman aside, the main reason why I love teaching particle physics is to be able to explain all the practical outcomes that have come from it, from PET scans in medical imaging to the creation of the medium by which you’re reading this now, the world wide web, invented at CERN as a means of quickly sharing data between physicists across the globe.

Throughout a regular day people use the discoveries from particle physics without even realising it. The laptop I am writing this on has semiconductors and chips that have been made small due to research with particle accelerators.

For our students putting this into perspective helps understand why scientists get into their fields of research. Physicists don’t go into a field of research thinking “what is the practical application of this?” as they don’t necessarily know what they are going to find out.

More importantly for our students the content may not actually be the most important thing they are learning, but they are learning how to think like a scientist and following the scientific method.

To concluded, the actual knowledge gained from studying particle physics may not have a practical gain, but it exposes students to what I like to call the bonkers nature of the universe, while at the same time reinforcing the basic principles of the scientific method.

Rich Wrigley

Head of Science & Technology Faculty