| Yes Sigga; dark matter is another term for "we really don't know what this is so lets give it a name so it looks like we do". They do know they can't see it and they do know that things they can see like galaxies are gravitationally affected by 'something' there.
Claire we will always have some sort of explanation, valid or not. What I find interesting about cosmology and quantum mechanics is that today's explanations are far more amazing than any science-fiction. | 
