A Younger Age for the Universe

The age of the universe in the Big Bang model can be calculated from three parameters: Hubble's constant, h; the mass density of the universe, Omega_m; and the cosmological constant, Omega_lambda. Recent observations of the cosmic microwave background and six other cosmological measurements reduce the uncertainty in these three parameters, yielding an age for the universe of 13.4 +/- 1.6 billion years, which is a billion years younger than other recent age estimates. A different standard Big Bang model, which includes cold dark matter with a cosmological constant, provides a consistent and absolutely time-calibrated evolutionary sequence for the universe.Comment: 14 pages, including 5 figures, also available at http://nedwww.ipac.caltech.edu/level5/Lineweaver/frames.htm

Is the Pre-WMAP CMB Data Self-consistent?

Although individual observational groups vigorously test their data sets for systematic errors, the pre-WMAP CMB observational data set has not yet been collectively tested. Under the assumption that the concordance model is the correct model, we have explored residuals of the observational data with respect to this model to see if any patterns emerge that can be identified with systematic errors. We found no significant trends associated with frequency, frequency channels, calibration source, pointing uncertainty, instrument type, platform and altitude. We did find some evidence at the ~ 1 to ~ 2 sigma level for trends associated with angular scale (l range) and absolute galactic latitude. The slope of the trend in galactic latitude is consistent with low level galactic contamination. The residuals with respect to l may indicate that the concordance model used here needs slight modification. See Griffiths & Lineweaver (2003) for more detail.Comment: 8 pages, 4 figures, to be published in the proceedings of "The Cosmic Microwave Background and its Polarization", New Astronomy Reviews, (eds. S. Hanany and K.A. Olive

The Observational Case for Jupiter Being a Typical Massive Planet

We identify a subsample of the recently detected extrasolar planets that is minimally affected by the selection effects of the Doppler detection method. With a simple analysis we quantify trends in the surface density of this subsample in the period - Msin(i) plane. A modest extrapolation of these trends puts Jupiter in the most densely occupied region of this parameter space, thus indicating that Jupiter is a typical massive planet rather than an outlier. Our analysis suggests that Jupiter is more typical than indicated by previous analyses. For example, instead of M_Jup mass exoplanets being twice as common as 2 M_Jup exoplanets, we find they are three times as common.Comment: 17 pages, 6 figures, conforms to version accepted for publication in "Astrobiology", includes new comparison with microlensing constraints on Jupiter-like planet

An Estimate of the Age Distribution of Terrestrial Planets in the Universe: Quantifying Metallicity as a Selection Effect

Planets like the Earth cannot form unless elements heavier than helium are available. These heavy elements, or `metals', were not produced in the big bang. They result from fusion inside stars and have been gradually building up over the lifetime of the Universe. Recent observations indicate that the presence of giant extrasolar planets at small distances from their host stars, is strongly correlated with high metallicity of the host stars. The presence of these close-orbiting giants is incompatible with the existence of earth-like planets. Thus, there may be a Goldilocks selection effect: with too little metallicity, earths are unable to form for lack of material, with too much metallicity giant planets destroy earths. Here I quantify these effects and obtain the probability, as a function of metallicity, for a stellar system to harbour an earth-like planet. I combine this probability with current estimates of the star formation rate and of the gradual build up of metals in the Universe to obtain an estimate of the age distribution of earth-like planets in the Universe. The analysis done here indicates that three quarters of the earth-like planets in the Universe are older than the Earth and that their average age is 1.8 +/- 0.9 billion years older than the Earth. If life forms readily on earth-like planets - as suggested by the rapid appearance of life on Earth - this analysis gives us an age distribution for life on such planets and a rare clue about how we compare to other life which may inhabit the Universe.Comment: 13 pages, 2 figures, minor revisions to conform to accepted Icarus version, in pres