We explore how local , cosmology-independent measurements of the Hubble constant and the age of the Universe help to provide a powerful consistency check of the currently favored cosmological model ( flat \Lambda CDM ) and model-independent constraints on cosmology .
We use cosmic microwave background ( CMB ) data to define the model-dependent cosmological parameters , and add local measurements to assess consistency and determine whether extensions to the model are justified .
At current precision , there is no significant tension between the locally measured Hubble constant and age of the Universe ( with errors of 3 % and 5 % respectively ) and the corresponding parameters derived from the CMB .
However , if errors on the local measurements could be decreased by a factor of two , one could decisively conclude if there is tension or not .
We also compare the local and CMB data assuming simple extensions of the flat , \Lambda CDM model ( including curvature , dark energy with a constant equation of state parameter not equal to -1 , non-zero neutrino masses and a non-standard number of neutrino families ) and find no need for these extra parameters ; in particular , we constrain the effective number of neutrino species to be N _ { eff } < 4 at 95 % confidence .
We show that local measurements provide constraints on the curvature and equation of state of dark energy nearly orthogonal to those of the CMB .
We argue that cosmology-independent measurements of local quantities at the percent level would be very useful to explore cosmology in a model-independent way .