8 ms·
The Hubble parameter. It's not defined to be constant in time, only in space.
by jobigoud 7y ago
The Hubble parameter. It's not defined to be constant in time, only in space.
- DiogenesKynikos 7y agoThe Hubble parameter is a function of redshift (or time, equivalently): H(z). The Hubble constant is H_0 := H(z=0). The discrepancy is in H_0. That implies a discrepancy at other redshifts as well, though how you connect H_0 to H(z) depends on your cosmological model. That's why the discrepancy in H_0 measurements is model-dependent. Different experiments are sensitive to the expansion rate during different epochs of cosmic history.