So we have more compelling evidence that it's there and we're beginning to unravel its shape!
In the February issue of Physics World, Douglas Clowe and Dennis Zaritsky discuss how studies announced in August last year of one of these cluster mergers, nicknamed the "Bullet Cluster", have given astrophysicists some of the best evidence yet for the existence of dark matter.
Work to produce the first ever 3D map showing the distribution of dark matter in the universe has been reported in New Scientist, 13 January 2007. The map was created by combining measurements of intervening matter by gravitational lensing of light from distant galaxies with data on distance derived from red shift measurements of the galaxies
Now the worry is that there are regions where there is dark matter but no visible matter and vice versa.
What if dark matter were not quite in our dimensions? What if it were to occupy a space very adjacent to our own and were to develop with a subtly different set of 'fundamental' constants. It would neither mirror nor shadow visible matter yet it would influence the matter in our niche in the Universe; and of course vice versa.
