After the Homestake Mine closed in 2003 , several underground rooms were retrofitted as a dedicated science facility . Meg ##g : A mile down in an old coal mine , we search for ` ` dark matter '' particles . Urry : Putting the experiment deep underground finds out particles other than dark matter . We detect dark matter only by gravitational effect , but it is most of the universe 's mass . Urry : Nobody has seen it , but experiment shows earlier weak detections were not real .
Meg ##g : A mile down in an old coal mine , we search for ` ` dark matter '' particles . Urry : Putting the experiment deep underground finds out particles other than dark matter . We detect dark matter only by gravitational effect , but it is most of the universe 's mass . Urry : Nobody has seen it , but experiment shows earlier weak detections were not real .