6,844 research outputs found
Is Cosmology Solved?
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
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
(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
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
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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