Over the past century better observations have led to ever
more precise measurements of the global properties of the
Universe. However, this tremendous progress has not led to a
better understanding, because the main constituents of the
Universe remain to be explained. The discovery that the Universe is
accelerating (made only 14 years ago) is arguably one of the greatest
findings of the past few decades. We lack a theoretical framework to
explain the fundamental physics that gives rise a largely dark
Universe, and progress will have to come from a significant improvement
in the precision of the measurements. In this talk I will
highlight the main problems facing 21st century cosmology and how we
plan to tackle them over the next 15 years.
