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Dark matter makes up almost everything that there *is*. But we can't see it. 86% of the
matter we think the universe is made of doesn't interact with the sort of matter we're made
of. That's why we call it dark, because we can see that it should be there, but it isn't.
Which might actually mean that it's not there, and something else is. But at the moment,
dark matter is our best guess.
It's one of the driving forces of the universe, the force which gives galaxies enough mass
to stop them from spinning apart. And like gravitational waves and the higgs boson, it
seems we could be pretty close to finding dark matter, and filling in one of the biggest
holes in our understanding of the cosmos.
And the most likely place to find it? A chamber a mile down a mineshaft in South Dakota, once
home to gold prospectors. Now home to dark gold prospectors. Or the LUX experiment. Many
people are searching for dark matter, but LUX is seen as one of the most promising experiments.
It's a highly sensitive array designed to detect WIMPS, Weakly Interacting Massive Particles.
The idea is that Dark matter must be particles, because it's matter, and there are billions
of them streaming through the Earth every second, because they make up over 80% of the
weight of the universe. But they very rarely bump into regular matter, and when they do,
they only have the tiniest interaction with them. LUX features a vast chamber filled with
liquid Xenon, which flashes when particles interact with it, and a detector array designed
to be sensitive enough to pick up those interactions. It has to be a mile under the urface to filter
out cosmic rays, which would interfere with the experiment.
And the people behind it are pretty confident it'll work - Lux has been confirmed as the
most sensitive experiment of its kind and although it's 90 day calibration and shakedown
run didn't detect anything, but the team say they are confident that, if anything is out
there, they should pick it up at least once on their upcoming 300 day run. That won't
be enough to confirm dark matter on its own, it'll need to happen repeatedly to be considered
proof that a new particle has been found.
Having said that, LUX isn't the only experiment out to prove, or disprove, the existence of
dark matter. The large Hadron Collider's having a go too, by creating it's own dark matter
in particle smashing experiments, and various space-based tests are also looking for tell-tale
signs of WIMP interactions.