What's it made of?Because we can't see them, nobody really knows what dark matter and energy are made of. But scientists have got lots of ideas, particularly about dark matter.
One idea is that every particle we know of has a 'partner' particle that we haven't discovered yet. These so-called 'sparticles' are much heavier than ordinary particles. This idea is called supersymmetry, and sparticles could be one of the things that make up dark matter.
Video: Science Museum
Requires Windows Media Player v6.4 or greater. more information