It is an exciting time to be a physicist, particularly in Australia. In mid-2012, the Higgs boson was discovered at CERN, and physicists from Melbourne contributed to the development of the ATLAS detector that participated in the discovery.
Then came the first direct detection of gravitational waves in early 2016, with Australian contributors from the University of Adelaide, the Australian National University and the University of Western Australia.
Now, just reported in Nature, is another breakthrough in fundamental physics, this time concerning antimatter. And this is another area where Australian researchers have been very active.
The researchers at CERN managed to isolate several atoms of antihydrogen – the antimatter analogue of hydrogen – and measure its properties with unprecedented accuracy.
While Australian researchers were not formally part of this experimental program, we have been providing calculations that show how to increase substantially the number of antihydrogen atoms made.
Why the interest in antihydrogen, or antimatter in general? It turns out that along with dark energy and dark matter, the existence of antimatter is quite a mystery to physicists.
The biggest puzzle is why there is so much matter in the universe, and so little antimatter. It would have been much easier to explain if there were equal amounts of matter and antimatter in the universe, or none at all.
The Standard Model predicts equal amounts of antimatter and matter being created by the Big Bang, but in reality there is a tiny amount of antimatter compared to matter. Why is this so? No one knows, and a Nobel Prize awaits whoever solves this problem.
It gets even more interesting, though. As there is no unification between quantum mechanics and general relativity, we have no reason to believe that antimatter will behave in a gravitational field in the same way as does matter.
This is something that physicists would very much like to test. But to do so, we need to create a substantial quantity of antimatter.