Interview with the author

What is particle physics?

It’s where you get if you keep asking ‘why?’. It describes how the Universe works deep down. What is the world made of? What are the ingredients and how do they behave, how do they interact? It started 100 or so years ago when we realised there was a substructure within what we thought of as the most basic building blocks of matter. Since the discovery of the electron we’ve discovered dozens and dozens and dozens of [subatomic] particles.

Do we understand why anything exists?

We can tell a lot of the story. You can break an apple pie down to chemical elements and trace their origins through the Universe’s history. Everything, including apple pies, contains hydrogen, carbon, oxygen, the chemical elements across the periodic table. We have a pretty complete description of where these come from, forged inside stars or in the first minutes after the Big Bang. We can tell this story back to about a trillionth of a second after the Big Bang, but it’s less clear beyond that.

What does the Large Hadron Collider do?

What it does is simple and pretty brutal: it accelerates particles to high energies and smashes them into each other. It does that 40 million times a second, 24 hours a day, seven days a week for nine months of the year. When two protons collide, they have a lot of kinetic energy and that is turned into new matter. You are making particles from energy, and you might make a Higgs boson, for example. That is how these particles were discovered.

Dr Harry Cliff is a particle physicist at the University of Cambridge working on the Large Hadron Collider beauty experiment