Abstract. The age of the Universe depends on both the present-day Hubble Constant and on the history of cosmic expansion. For decelerating cosmologies such as Ωm = 1, the dimensionless product H0 t0 < 1 and modestly high values of the Hubble constant H0> 70 would be inconsistent with a cosmic age t0 larger than 12 Gyr. But if ΩΛ> 0, then H0 t0 can take on a range of values. Evidence from the Hubble diagram for high redshift Type Ia supernovae favors ΩΛ ∼ 0.7 and H0 t0 ∼ 1. Then, if H0 lies in the range 65–73, the age of the Universe, t0, is 14 ± 1.6 Gyr. 1. It has been an interesting five years! Five years ago, the combination of deep seated belief in inflation, implying Ω = 1, and stellar age estimates near 15 Gyr seemed to require H0 ∼ 40. Measurements of H0 ∼ 60 and Ωm ∼ 0.3 in clusters notwithstanding, Bartlett, Blanchard, Silk, and Turner wrote a provocative paper entitled, “The Case for a Hubble Constant of 30 km/s/Mpc. ” Persuaded by the power of theoretical reasoning, Joe Silk bet Brian Schmidt and me a case of Scotch that H0 < 60. While Joe has not ye
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