|
You are here:
BBC >
Science & Nature >
Space >
Deep Space >
Dark Matter
|
|
| WIMPs
MACHOs
Neutrinos
Highly Strung
Dark Energy
Does Dark Matter?
|
WIMPS
Why are physicists looking underground to try to find the missing mass of the Universe?
 
Well, they're searching for WIMPs. A WIMP is a Weakly Interacting Massive Particle. This is a type of 'exotic' particle that is one of the candidates for the mysterious dark matter that's missing from the Universe. Although they were formed in distant places, 'exotic' just means that they are different to the ordinary particles that make up the world around us. WIMPs have never been found, but physicists think that there could be loads of them flying straight through us all the time. In fact about a million of them could be passing through your fingernail this very second!
If there are so many flying around, how come we haven't spotted one yet? Although they are called 'weak', they are amazingly strong - they can pass through solids without stopping. And they are not the only things that are zooming down from space - we are also being bombarded by cosmic rays. Both these factors make them extremely difficult to detect.
But what makes WIMPs special is their ability to travel straight through solid objects. So one of the best ways to catch them is to go deep underground. The UKDMC project is housed 1100m down the deepest mine in Europe and the GENIUS team work from inside the Gran Sasso mountain in Italy. Seemingly strange locations to study the Universe, but the feature that both these places have in common is rock, tons of it. The thick rock walls act as a natural filter, so as the space particles travel downwards, the cosmic rays collide with the atoms in the rock and are halted. WIMPs should be able to pass straight through the rock and out into the caverns below where they can be detected.
Teams from all around the world are currently racing to find out whether these elusive particles exist. If they do, they'll form just one of the missing pieces in the jigsaw puzzle of dark matter. It's estimated that they could contribute up to 90% of dark matter. The other main contenders for the rest are MACHOs and neutrinos.
|
|
|
|
