2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/12396Four Hubble diagrams are combined to test for the linearity of the cosmic expansion field. The expansion rate, H_0, is found to decrease by ~5% out to 18000km/s. Beyond this distance the mean value of H_0 is close to the value at 10000km/s. The absolute value of H_0 is derived in two different ways. The one leads through Cepheids from HST and blue SNe Ia to H_0=57+/-7 (external error) at 30000km/s. The other uses various distance indicators to the Virgo cluster whose distance can be extended to 10000km/s by means of only relative cluster distances; the result of H_0 is closely the same. Independent distances from purely physical methods (SZ effect, gravitational lenses, and MBW fluctuations) cluster about H_0(cosmic)=58.16 pages, LaTeX (mprocl.sty + psfig.sty), 8 figures. To be published in "General Relativity", 8th Marcel Grossmann Symposium, ed. T. Piran, Singapore: World SientificAstrophysicstext