Things the Standard Model does not explain

Things the Standard Model does not explain Despite those successes, there are quite a few features of the Universe not explained by the Standard Model. Why does the Universe contain matter but no antimatter? Why is the ’dark matter’, whose presence is needed to allow galaxies to form and to hold them together once they do? Why do observations show that the Universe’s expansion is presently accelerating? What causes irregularities in the density field of the primordial Universe, seen directly in the cosmic microwave background? These may be evidence of the need for new physics beyond the Standard Model.