  Consistency relations between growth of structure and expansion history
observables exist for any physical explanation of cosmic acceleration, be it a
cosmological constant, scalar field quintessence, or a general component of
dark energy that is smooth relative to dark matter on small scales. The
high-quality supernova sample anticipated from an experiment like SNAP and CMB
data expected from Planck thus make strong predictions for growth and expansion
observables that additional observations can test and potentially falsify. We
perform an MCMC likelihood exploration of the strength of these consistency
relations based on a complete parametrization of dark energy behavior by
principal components. For LCDM, future SN and CMB data make percent level
predictions for growth and expansion observables. For quintessence, many of the
predictions are still at a level of a few percent with most of the additional
freedom coming from curvature and early dark energy. While such freedom is
limited for quintessence where phantom equations of state are forbidden, it is
larger in the smooth dark energy class. Nevertheless, even in this general
class predictions relating growth measurements at different redshifts remain
robust, although predictions for the instantaneous growth rate do not. Finally,
if observations falsify the whole smooth dark energy class, new paradigms for
cosmic acceleration such as modified gravity or interacting dark matter and
dark energy would be required.
