The Large Hadron Collider buried deep under the Swiss-France border is at the frontier of mankind’s quest to understand the universe. Only this month the elusive Higgs Boson was detected, ending the forty-year search for a complete Standard Model.
Sydney University was hardly likely to miss being involved in such a groundbreaking project. We currently have a team of thirteen students and physicists working in collaboration with universities from over one hundred counties to process the data collected by the ATLAS detector.
I caught up with Mark Scarcella, one of Sydney Uni’s PhD students who worked with scientists at CERN for three months, to hear about the University of Sydney’s involvement firsthand.
Honi Soit: What was it like spending three months at CERN?
Mark Scarcella: Its an interesting place – it looks like its from the 60s, its all old and there’s a maze of buildings there. It’s full of pHD students and everyone’s always talking about physics.
HS: Why is the Higgs particle so important?
MS: In the Standard Model there is no way for W and Z particles to have mass. So physicists add a new particle called the Higgs particle and a new field called the Higgs field and it does all this lovely maths to give particles mass.
HS: Are scientists certain they have discovered the Higgs Boson?
MS: We’ve definitely found a new particle – there’s definitely something there – and as far as we can tell so far it looks like the Standard Model Higgs Boson. At the moment the error bar on our data is still very large so what we’re observing could be the Higgs Boson or it could be something else.
HS: How does the detector work?
MS: The one I work on is called the ATLAS detector. It’s a huge 40m long, 20m tall structure. You can think of it like a camera; when you take a photo with a camera photons come in through the lens, hit the plate and the camera reconstructs the image. That’s kind of what the silicon particle detector is, except instead of photons we have electrons and other fundamental particles flying out from collisions. There are also these other structures called calorimeters, which tell us the energy of a particle. On the outside are these huge layers that track particles and give us their position as they fly out from the detector. From that we build back to the very beginning and work out what happened when the particles collided.
HS: Does the Higgs Boson and the Standard Model explain everything or are there many mysteries in the universe yet to be discovered by future physicists?
MS: Heaps! The big one that people talk about is dark matter. The universe is only four per cent of what we know of matter and around 75 per cent is dark matter. Dark matter is matter that exists but doesn’t interact with anything that we know of; it doesn’t interact with photons very much at all so you can’t see the affect of that matter being there. We can detect it through galactic rotation curves. When galaxies rotate, the rotation speed versus the distance from the center of the galaxy doesn’t make sense in terms of gravity so there must be some extra mass out there causing things to spin this way. That mass we can’t see but we assume that there has to be something there and because we can’t see it we call it dark matter. And then dark energy is this other mystical thing where they’ve discovered the universe is expanding at an accelerating rate, that something is pushing everything apart in the universe and that it should be attributed to something called dark energy. We really have no idea – there are a lot of theories and we’re hoping to find some evidence of dark matter at the Large Hadron Collider but so far nothing.
HS: Does all this physics have any practical applications?
MS: In terms of whether the Higgs Boson will help me save money or something – it’s hard to say. But so much stuff comes from this research… I mean the World Wide Web was developed at CERN. People do so much research in the development of new particle detectors and all that technology eventually leaks out into the community and can be put to other purposes that people hadn’t really considered. The theories we are trying to test and the things we are trying to discover really is knowledge for knowledge’s sake at the moment…we don’t know where it’s going to go.