The Higgs boson, the last important piece of a nuclear physics jigsaw puzzle.

10 July 2012

The sun will rise tomorrow and, when I get out of bed, it will still be the middle of winter in Australia. But, just like finding out for sure that there are other intelligent beings in the universe, while nothing will appear to have changed, everything has.

Associate Professor Kevin Varvell, from the School of Physics, works on the ATLAS experiment at the Large Hadron Collider and writes about the significance of the Higgs boson finding.

On Wednesday evening Australian time, the leaders of the two large detection experiments at the Large Hadron Collider, or LHC for short, of the European Organisation for Nuclear Research (CERN) announced they now had evidence that made them more than 99.99 per cent certain of the existence of the Higgs boson, the particle that gives mass to all other particles in the visible universe, or something very like it.

So why is that important? Why did we spend the best part of $10 billion building one of the world's largest scientific instruments, about 27km in circumference, underneath the Swiss-French border? And why have we been using it to accelerate protons to within a hair's breadth of the speed of light so we can bash them together in the hope of creating this elusive particle?

Well, the first answer is the science one. The existence of the Higgs boson is the last important piece of the jigsaw puzzle in understanding how the visible part of our universe is put together. It was the missing ingredient for what is known as the Standard Model of particle physics.

The Standard Model has been incredibly successful in describing all the stuff that we're made of at the most fundamental level. It has been around for almost 40 years. Every measurement to date trying to look for chinks in the armour of the Standard Model has shown that it's quite capable of explaining everything that we are familiar with in the "low energy" world of particles - low energy compared with the moments immediately after the big bang, that is. But the Higgs boson was a significant missing ingredient not verified experimentally - until now.

So why is that important? Well, I can't point to an immediate practical application that will improve quality of life for everyone on Earth, although I know more than a few high-energy physicists who will feel a lot happier with life and breathe a lot easier, but it means we now have a dependable theory that explains how the universe we can sense around us is put together. And we can use it with more confidence to predict what is likely to happen to matter in unknown or novel circumstances.

I can also say that the better we understand our universe, the more pathways to the future open up. Without Newton's analysis of motion in the late 17th century, which led to his expounding of the theory of gravity, for instance, we would not have been able to send astronauts to the moon - and we wouldn't have all the practical benefits that have emerged from NASA's space program.

Without the development of radio telescopes for use in the search for black holes in space, we wouldn't have developed the mathematical techniques for processing radio signals that CSIRO electrical engineers employed to ensure wireless data transmissions are secure and dependable. In other words, WiFi communications, which are changing our lives so radically, would not exist.

What I can predict for a future with the certainty of knowledge that the Higgs boson exists is a lot more work. What we've found is a missing particle but we don't know much about it yet. We need to measure it, analyse it, describe it and sketch out its properties. That's going to take us at least another couple of decades.

It's also going to take a lot more collisions. After an initial hiccup just after its start-up in 2008, which set us back a year, the LHC has performed superbly, delivering more proton-proton collisions than we could reasonably expect of a new machine at the start of its working life. One key to fleshing out the secrets of this new particle is to make as many as possible, all the easier then to tease it out from among the millions and millions of collisions a second that don't contain a Higgs but might fool us into thinking that one was there.

Then there is the possibility that nature has dealt us something even more interesting. Physicists have reason to believe that, for a number of well-motivated reasons, the Standard Model with its single Higgs boson cannot serve as the ultimate theory of the subatomic world. What is the dark matter that we now know makes up a sizeable part of the universe? Are there extra dimensions of space as yet unrevealed to our experiments?

The experiments at the LHC are already busy searching for other new things, evidence for theories that take us beyond our Standard Model, some with multiple Higgs bosons, and with particles that might in fact be that dark matter out there in the universe. There is no shortage of ideas or enthusiasm to carry on and test them.

Whatever anyone else thinks, things have changed for me, if just a little.

Somehow my scientific life is a lot more certain and a lot more comprehensible than it was. And, even if this week's news comes from the somewhat abstract world of particle physics, if we can conceive of, produce and capture the Higgs boson, then I have a lot more faith in the capacity of humans to tackle other challenges we face as we confront the future.

Contact: Katynna Gill

Phone: 02 9351 6997

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