10 research outputs found

    The Hubble Constant

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    I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of their distance by geometric means. The second category comprises the use of all-sky cosmic microwave background, or correlations between large samples of galaxies, to determine information about the geometry of the Universe and hence the Hubble constant, typically in a combination with other cosmological parameters. Many, but not all, object-based measurements give H0H_0 values of around 72-74km/s/Mpc , with typical errors of 2-3km/s/Mpc. This is in mild discrepancy with CMB-based measurements, in particular those from the Planck satellite, which give values of 67-68km/s/Mpc and typical errors of 1-2km/s/Mpc. The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant. Whether a discrepancy exists, and whether new physics is needed to resolve it, depends on details of the systematics of the object-based methods, and also on the assumptions about other cosmological parameters and which datasets are combined in the case of the all-sky methods.Comment: Extensively revised and updated since the 2007 version: accepted by Living Reviews in Relativity as a major (2014) update of LRR 10, 4, 200

    Does Economics have an Effect? Towards an Economics of Economics

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    "Due to its formality and highly analytic thinking, economics is often attributed a leading role among the social sciences and a prominent position as contributor to economic or social issues in the real world. Fact is, however, that the empirical proof for such a claim is either missing or anecdotal. This paper aims to outline the “economics of economics”. It surveys and compares approaches of impact measurement such as a production function of economics or the demand and supply of trained economists and discusses the determinants of the strength of the influence of economics. It furthermore discriminates between the impact of economic ideas versus that of economists as scientists or politicians.

    Methods for the Study of mRNA Synthesis in Bacteriophage-Infected E. coli

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    Sites of Hormonal Regulation of Protein Metabolism

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    Radio and millimeter continuum surveys and their astrophysical implications

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