One of the problems with searching for dark matter is that while it appears to interaction gravitationally, it's very difficult to detect by means of its interaction with other particles. Physicists propose WIMPs as a way of resolving this problem, because they have two key features:
- WIMPs interact only through gravitation and the weak nuclear force (no electromagnetic or strong nuclear interations - or, if there is such an interaction, it's extremely limited)
- WIMPs contain a high mass in comparison to other known particles.
So far there is no conclusive evidence in support of the existence of WIMPs, although in 2009 the Cryogenic Dark Matter Search (CDMS) experiment announced two pieces of data from their detectors which may have been WIMPs.