Experts hope LHC will help explain dark matter

By Fred Watson 30 May 2012
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Space mysteries are closer to being uncovered thanks to findings of the Large Hadron Collider.

MOST PEOPLE ARE probably aware of the Large Hadron Collider (LHC), the giant atom smasher that straddles the Swiss–French border near Geneva. This extraordinary machine whizzes subatomic particles around a 27km circular path, banging them together at very near the speed of light. Unfortunately for spectators – or perhaps fortunately – most of the high-energy action takes place deep underground, where a tunnel houses the twin vacuum tubes containing particle beams moving in opposite directions.

Why should a machine designed to probe phenomena on a sub-microscopic scale be of interest to astronomers, who study nature on the largest scale? Finding the Higgs boson – the subatomic particle that endows everything in the Universe with mass – is one good reason, and the latest buzz from the LHC is quite promising on this front. A signal officially described as ‘intriguing’ has been detected in two of the LHC’s experiments.

However, there are two deeper mysteries that have plagued astronomers over the past few decades. The first is that four-fifths of the matter in the Universe is completely invisible to us, and only reveals itself by its gravity. Our best guess is that this elusive ‘dark matter’ is made up of vast quantities of an unknown subatomic particle.

Understanding ‘dark matter’

The boffins who earn their daily bread theorising about the subatomic world suspect that there is an entire suite of undiscovered particles that are shadows of the ones we know about. One particular type of these ‘supersymmetric’ particles could explain dark matter, and the hope is that it will be found at the LHC. So far, nothing has been revealed – but the search is still in its infancy.

That’s the relatively good news. The bad news concerns the other deep mystery, which is that the expansion of the Universe is getting faster because of something astronomers call ‘dark energy’. It’s a kind of springiness of space itself, and its origin is an enigma that might only be understood by the discovery of completely new physics. Although there is hope that the LHC might shed, er… light on that, we are, at the moment, completely in the dark.

Fred Watson is astronomer-in-charge of the Australian Astronomical Observatory.

Source:Australian Geographic Nov – Dec 2011