All of our evidence for dark matter is indirect, that is, we
deduce the existence of substantial amounts of dark matter –
exceeding the amount of ‘ordinary matter’ by 5 times – from its
gravitational effects at large distances, on the scale of
galaxies, clusters of galaxies, and even across regions of a
billion light-years in size. The generally favored hypothesis is
that dark matter is composed of some sort of new weakly
interacting massive particle (WIMP). Such a WIMP would not
interact via the electromagnetic force or the strong nuclear
force, and thus is very hard to detect directly. There are a
number of experiments underway attempting to directly detect the
elusive particle. The majority of these are earthbound
experiments wherein ordinary matter in crystalline form is used
as the detector. Three of these experiments are in fact claiming
statistically significant detection rates, the DAMA/Libra
experiment in Italy, the CRESST experiment based in Germany, and
the COGENT experiment in the U.S. In this cla