Question: what is dark matter

David Wilson answered on 11 Nov 2014:

Dark matter is the name we’ve given for stuff we haven’t found yet, but musk make up about 3/4s of all the stuff in the Universe. We found it by studying how fast galaxies spin. Lost off them seem to spin too fast so that the gravity form the stuff that we can see couldn’t hold them together. There must be a load more transparent stuff that has mass, and therefore gravity, but doesn’t interact with light (so we can’t see it). We think it many be some sort of exotic particle, and machines like the Large Hadron Collider in Switzerland might spot them in the next few years. Or they might not!