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Astrophysical Ages and Time Scales ASP Conference Series, Vol. TBD, 2001

By N. Manset, C. Simpson, Type Ia Supernovae, The Hubble Constant, Cosmological Constant and John L. Tonry


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

Year: 2001
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