2.7. Recap: The New Emerging Cosmology

Using a host of diverse observations made possible by advances in technology, we have now defined the basic features of the Universe: it is spatially flat and 13 Gyr old with a currently accelerating expansion, comprised of one third dark matter and two thirds dark energy. The variety and redundancy of observations is important: the overall picture does not depend on just a single measurement or type of measurement. Consistency checks on the age, the baryon and matter densities, and the total density and spatial curvature have increased our confidence both in the description as well as in the overall framework. We now move from discussion of the basic features of the universe to the underlying physics that forms the basis for our current understanding.