What does a particle physicist do? We asked one to find out
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What does a particle physicist do? We asked one to find out
We recently caught up with a particle physicist working at CERN and asked him some of the biggest questions concerning the nature of the Universe around us.
Have you ever wanted to ask a particle physicist what it is that they actually do? Luckily, we got the change to ask one that very question.
Gavin Hesketh is an experimental particle physicist working on the Large Hadron Collider.
His book The Particle Zoo seeks to answer some of the fundamental questions about our Universe.
BBC Sky at Night Magazine caught up with Hesketh to find out more about what a particle physicist actually does, and why this work is vital to our understanding of the cosmos.
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What does a particle physicist do?
As a particle physicist, I do much the same as astronomers: try to learn more about the Universe we live in.
Astronomers use telescopes on mountain tops or even in space to look out to the cosmos, which is dominated by the force of gravity: massive objects like stars pulling at each other across immense distances.
Particle physicists build our experiments deep underground to shield them from cosmic rays (subatomic particles from outer space bombarding Earth all the time).
We look at the Universe on the smallest scales, a world dominated by the electromagnetic, weak and strong nuclear forces.
These are the forces that hold atoms together, and explain the structure of matter.
What is so exciting today is that we are connecting these different fields as we try to explain some of the mysteries of astronomy, like dark matter, using particle physics.
The ATLAs experiment at the Large Hadron Collider. Credit: CERN / Maximilien Brice
What can particle physics tell us about our own Solar System and Galaxy?
Over the last century, particle physics has definitely benefited from astronomy!
In the early 20th Century, cosmic rays were used to discover antimatter, as well as the first completely new particles: the muon and strange quark.
As the Sun fuses nuclei, it emits countless numbers of ghostly neutrino particles (billions pass through us every second and we don’t even notice).
Studying these led to the 2015 Nobel Prize in physics being awarded to Takaaki Kahita and Arthur McDonald for discovering that they have tiny masses.
But particle physics has also given back.
Without it, we couldn’t explain how stars burn in the first place.
Particle physics is important to understand some of the most dramatic events in the Universe, like supernovae.
Neutrino experiments around the world now also double up as 'neutrino telescopes', looking for the highest energy particles and trying to understand what in the cosmos could be producing them.
So today there is more and more of an overlap between particle physics and astronomy.
DUNE, the Deep Underground Neutrino Experiment currently under construction in the USA, will produce the most intense beam of neutrinos ever constructed
As the world’s most powerful particle accelerator, it accelerates particles.
Protons in fact, and it gets then very close to the speed of light before crashing them head on
In these collisions we recreate some of the conditions of the very hot and energetic Universe just a fraction of a second after the Big Bang.
So the Large Hadron Collider can help to tell us how the Universe evolved from the Big Bang to the atoms, molecules, stars and planets that exist today.
And if, like all particle physicists hope, we turn up something unexpected, this will tell us something new about the Universe, and how it formed.
It might be a new force of nature, extra dimensions of space, or the elusive dark matter.
Dark matter holds galaxies together, but it cannot be directly detected. Credit: ESA/Hubble & NASA, A. Riess, D. Thilker, D. De Martin (ESA/Hubble), M. Zamani (ESA/Hubble)
What's the smallest thing we can see?
Size is a funny idea in particle physics.
We are definitely looking at very small things, but when it comes to the fundamental particle, well, we have no idea how small they really are.
Even something everyday like the electron, the particle that powers all our TVs, phones, and so on.
Electrons are so small we haven’t been able to measure their size yet.
Perhaps if we are able to hit them hard enough, they will break apart into smaller things.
What is the Higgs boson? This video by Dave Barney of the CMS collaboration and Steven Goldfarb of the ATLAS collaboration reveals all. Animation by Jeanette Nørgaard for TED-Ed.
But there is no sign of this happening yet, and based on the experiments we have done so far, we know that all particles must be smaller than 10-18m, or less than a billionth of a billionth of a metre.
String theory suggests particles could be another billion billion times smaller; so small we may never be able to actually measure their size.
