Over 80 per cent of the matter in the Universe is made up of this stuff, but despite its name it can’t simply be made up of dead stars, gas and dust. Dark matter has to consist of something more exotic than standard atomic particles to ensure the Big Bang produces a universe chemically similar to the one we see.
Such observational constraints have forced theorists to focus on a handful of candidates for dark matter.
The main contenders include so-called weakly interacting massive particles (‘WIMPs’) and gravitinos, whose existence is predicted by theories aimed at unifying all the fundamental forces and particles of nature, and axions,predicted to exist by theories of how atomic nuclei hold together. Experiments now underway at the Large Hadron Collider could soon reveal the truth.
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