Governato et al. have offered a solution to a long-standing puzzle about structure formation. Published in the current issue of Nature. http://arxiv.org/abs/0911.2237 Dark matter dynamics (esp. with supercomputer simulations) has already explained a lot about structure formation. For an overview, George Smoot has an excellent 18 minute talk---google "Smoot TED". Earlier simulations reproduced a realistic picture of largescale filamentary (cobwebby) structure of matter that we actually see, the size and distribution of clusters of galaxies, the formation of individual large galaxies. But the simulations did not give a realistic picture of the tiny dwarf galaxies which have a lower concentration stars and other forms of ordinary matter in their centers than the sims predicted. Overall the dark matter explanation of largescale structure worked remarkably well but there was this nagging discrepancy. Governato et al included the affects of supernova winds and got a supercomputer simulation that reproduces the realistic appearance of a dwarf galaxy. There is a beautiful animated film of the formation of a dwarf galaxy, based on supercomputer sim. http://www.sciencenews.org/view/generic/id/54015/title/Supernova_winds_blow_galaxies_into_shape In the video you can see the supernovae exploding and blowing away part of the ordinary matter. Time is speeded up and the video gradually zooms out, as the small protogalaxy blobs collide, coalesce, as the galaxy grows, and as its spiral structure gradually develops.