"In 1929 Hubble announced... a "roughly linear" relation between and distance. ...His data points ...did not really support a linear relation. But in the early 1930s he had measured redshifts and distances out to the , with a redshift z \eqsim 0.02, corresponding to... 7,000 km/sec and a linear relation... was evident. The conclusion... the universe is really expanding. ...At the time of writing, the largest... z=6.96. It may eventually become possible to measure the expansion rate H(t) \equiv \dot{a}(t)/a(t) at times t earlier than the present, by observing the change in very accurately measured redshifts of individual galaxies over times as short as a decade."