Issues for the next generation of galaxy surveys

The weight of the evidence is that the mean mass density (excluding a cosmological constant or its equivalent) is less than the critical Einstein-de Sitter value. This result, if confirmed, is notable because so many of us believed the Einstein-de Sitter model is the elegant and sensible choice. It may offer a cautionary lesson: perhaps our search for a theory of structure formation should broaden the range of models under discussion, in case our first guesses disagree with Nature's choice. To that end I describe an isocurvature model that offers a viable and arguably attractive picture for the early assembly of galaxies that trace mass. Surveys in progress will be capable of distinguishing between this model and the commonly studied adiabatic cold dark matter theory, and may convincingly establish the nature of the initial conditions out of which the galaxies grew.