6,844 research outputs found

    Is Cosmology Solved?

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    We have fossil evidence from the thermal background radiation that our universe expanded from a considerably hotter denser state. We have a well defined and testable description of the expansion, the relativistic Friedmann-Lemaitre model. Its observational successes are impressive but I think hardly enough for a convincing scientific case. The lists of observational constraints and free hypotheses within the model have similar lengths. The scorecard on the search for concordant measures of the mass density parameter and the cosmological constant shows that the high density Einstein-de Sitter model is challenged, but that we cannot choose between low density models with and without a cosmological constant. That is, the relativistic model is not strongly overconstrained, the usual test of a mature theory. Work in progress will greatly improve the situation and may at last yield a compelling test. If so, and the relativistic model survives, it will close one line of research in cosmology: we will know the outlines of what happened as our universe expanded and cooled from high density. It will not end research: some of us will occupy ourselves with the details of how galaxies and other large-scale structures came to be the way they are, others with the issue of what our universe was doing before it was expanding. The former is being driven by rapid observational advances. The latter is being driven mainly by theory, but there are hints of observational guidance.Comment: 13 pages, 3 figures. To be published in PASP as part of the proceedings of the Smithsonian debate, Is Cosmology Solved

    BBN and the Primordial Abundances

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    The relic abundances of the light elements synthesized during the first few minutes of the evolution of the Universe provide unique probes of cosmology and the building blocks for stellar and galactic chemical evolution, while also enabling constraints on the baryon (nucleon) density and on models of particle physics beyond the standard model. Recent WMAP analyses of the CBR temperature fluctuation spectrum, combined with other, relevant, observational data, has yielded very tight constraints on the baryon density, permitting a detailed, quantitative confrontation of the predictions of Big Bang Nucleosynthesis with the post-BBN abundances inferred from observational data. The current status of this comparison is presented, with an emphasis on the challenges to astronomy, astrophysics, particle physics, and cosmology it identifies.Comment: To appear in the Proceedings of the ESO/Arcetri Workshop on "Chemical Abundances and Mixing in Stars in the Milky Way and its Satellites", eds., L. Pasquini and S. Randich (Springer-Verlag Series, "ESO Astrophysics Symposia"

    Topological Defects in an Open Universe

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    (To appear in Nuclear Physics B Supplements Proceedings section) This talk will explore the evolution of topological defects in an open universe. The rapid expansion of the universe in an open model slows defects and suppresses the generation of CBR fluctuations at large angular scale as does the altered relationship between angle and length in an open universe. Defect models, when normalized to COBE in an open universe, predict a galaxy power spectrum consistent with the galaxy power spectrum inferred from the galaxy surveys and do not require an extreme bias. Neither defect models in a flat universe nor standard inflationary models can fit either the multipole spectrum or the power spectrum inferred from galaxy surveys.Comment: 11 pages and 4 figures, Elsevier Publisher's LaTeX, POP-54

    How Do Community-based Legal Programs Work: Understanding the Process and Benefits of a Pilot Program to Advance Women's Property Rights in Uganda

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    This document presents women's property rights, especially access to land, are increasingly recognized as critical to achieving poverty reduction and gender equality. Research shows that community-based legal aid programs are a viable approach to improving legal knowledge and women's access to legal resources to address property issues. From 2009-2010, the International Center for Research on Women (ICRW) and the Uganda Land Alliance (ULA) implemented and evaluated a pilot program to strengthen women's property rights. This report describes the pilot program's implementation, outcomes and lessons. It details the program design, methodologies for monitoring and evaluation, and the context in which the program was implemented. Findings include a discussion of challenges encountered by the rights workers, overall program achievements, and recommendations for community rights work as an approach to promoting women's property rights

    CEP at 5: Comparative Data Enabling Higher-Performing Foundations

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    CEP at 5 reflects on CEP's first five years through stories and pictures from CEP's Five-Year Anniversary Event held in New York in September 2006. The report features a speech by Rockefeller Foundation Vice President Nadya Schmavonian, who details the insights her foundation gained using comparative data to assess its performance. The report also includes a talk by CEP Executive Director Phil Buchanan on "The Foundation Effectiveness Imperative," comments from foundation leaders, and descriptions of CEP's research agenda and assessment tools
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