The time scale test for Omega: the inverse Hubble constant compared with the age of the universe

The status of the HST program to calibrate the absolute magnitude at maximu m of non-peculiar Ia supernovae is reviewed. Assuming, in first approximati on, that SNe Ia are perfect standard candles gives an interim calibration, based on seven SNe Ia in six galaxies for which we have Cepheid distances, of [M-B(max)] = -19.52 +/- 0.07, [M-v(max)] = -19.48 +/- 0.07. Applying the se calibrations to the Hubble diagram of 52 fiducial SNe Ia with good photo metric data, and using a correction of 0.08 mag to an earlier adopted Cephe id period-luminosity relation gives H-0 = 55 +/- 5 km s(-1) Mpc(-1). Three other methods (via the Virgo cluster distance tied to the global expansion frame, the luminosity function of field spirals calibrated via Cepheids, an d the physical methods using gravitational lenses, the Sunyaev-Zeldovich ef fect, and expanding SN envelopes) confirm the long distance scale that is i mplied by this value. Second-parameter corrections to the supernovae method depending on decay rate affect this solution for H-0 by, at most, 5%. A cr itique is given of the Key Project result that H-0 > 70 (Freedman et al., 1 998). Disagreements with their precepts are discussed. The "Key Project" re sults, reduced to our Virgo cluster distance of 21.5 Mpc, gives H-0 = 55. A dopting 13.5 Gyr for the time since the beginning of the expansion gives a timing test value of Omega (total) = 0.44 (0.37, + 1.16). This shows that t he timing test for omega, although powerful in principal because it measure s the total mass, is presently impotent because the errors in H-0 and T-u a re too large. Our principal result is that there is no time scale crisis in Big Bang cosmology, sans cosmological constant, because H-0(-1) > T-u deci sively, using the long distance scale derived here. (C) 1998 Elsevier Scien ce B.V. All rights reserved.