380 research outputs found
The Big Bang, Modern Cosmology and the Fate of the Universe: Impacts upon Culture
Cosmological discoveries over the past century have completely changed our
picture of our place in the universe. New observations have a realistic chance
of probing nature on heretofore unimaginable scales, and as a result are
changing the nature of fundamental science. Perhaps no other domain of science
has an equal capacity to completely change our perspective of the world in
which we live.Comment: Invited Lecture, UNESCO/IAU Meeting: The Role of Astronomy in Society
and Culture Jan 2009, to appear, IAU Proceedings, D. Valls-Gaubaud and A.
Boksenberg, eds.. (Several typos removed in this version
Space, Time, and Matter: Cosmological Parameters 2001
Over the past three years, our confidence in the inferred values of
cosmological parameters has increased dramatically, confirming that the flat
matter dominated Universe that dominated cosmological model building for the
past 20 years does not correspond to the Universe in which we live. I review
recent developments here and quote best fit current values for fundamental
cosmological parameters.Comment: 19 pages, figures included. (Invited Review Lecture: Third
International Conference on the Identification of Dark Matter, York, England,
Sept 2000 - to appear in Proceedings
A New Cosmological Paradigm: the Cosmological Constant and Dark Matter
The Standard Cosmological Model of the 1980's is no more. I describe the
definitive evidence that the density of matter is insufficient to result in a
flat universe, as well as the mounting evidence that the cosmological constant
is not zero. I finally discuss the implications of these results for particle
physics and direct searches for non-baryonic dark matter, and demonstrate that
the new news is good news.Comment: 11 pages, latex, including 4 embedded figs. Based on invited lectures
at PASCOS98, Boston; Tropical Workshop on Particle Physics and Cosmology and
Particle Physics, San Juan; WEIN 98, Santa Fe. To appear in these proceeding
The State of the Universe: Cosmological Parameters 2002
In the past decade, observational cosmology has had one of the most exciting
periods in the past century. The precision with which we have been able to
measure cosmological parameters has increased tremendously, while at the same
time, we have been surprised beyond our wildest dreams by the results. I review
here recent measurements of the expansion rate, geometry, age, matter content,
and equation of state of the universe, and discuss the implications for our
understanding of cosmology.Comment: 20 pages, To appear in Proceedings, ESO-CERN-ESA Symposium on
Astronomy, Cosmology and Fundamental Physics, March 2002. Typo in final table
fixe
From B Modes to Quantum Gravity and Unification of Forces
It is commonly anticipated that gravity is subject to the standard principles
of quantum mechanics. Yet some (including Einstein) have questioned that
presumption, whose empirical basis is weak. Indeed, recently Freeman Dyson has
emphasized that no conventional experiment is capable of detecting individual
gravitons. However, as we describe, if inflation occurred, the Universe, by
acting as an ideal graviton amplifier, affords such access. It produces a
classical signal, in the form of macroscopic gravitational waves, in response
to spontaneous (not induced) emission of gravitons. Thus recent BICEP2
observations of polarization in the cosmic microwave background will, if
confirmed, provide empirical evidence for the quantization of gravity. Their
details also support quantitative ideas concerning the unification of strong,
electromagnetic, and weak forces, and of all these with gravity.Comment: 4 pages, no figures. v2: minor typos corrected, reference added. v3:
very minor typo corrected. Winning entry in Gravity Research Foundation essay
competitio
Theoretical Uncertainties in the Subgiant--Mass Age Relation and the Absolute Age of Omega Cen
The theoretical uncertainties in the calibration of the relationship between
the subgiant mass and age in metal-poor stars are investigated using a Monte
Carlo approach. Assuming that the mass and iron abundance of a subgiant star
are known exactly, uncertainties in the input physics used to construct stellar
evolution models and isochrones lead to a Gaussian 1-sigma uncertainty of
+/-2.9% in the derived ages. The theoretical error budget is dominated by the
uncertainties in the calculated opacities.
Observations of detached double lined eclipsing binary OGLEGC-17 in the
globular cluster Omega Cen have found that the primary is on the subgiant
branch with a mass of M = 0.809+/-0.012 M_sun and [Fe/H]= -2.29+/-0.15 (Kaluzny
et al. 2001). Combining the theoretical uncertainties with the observational
errors leads to an age for OGLEGC-17 of 11.10+/-0.67 Gyr. The one-sided, 95%
lower limit to the age of OGLEGC-17 is 10.06 Gyr, while the one-sided, 95%
upper limit is 12.27 Gyr.Comment: 4 pages, 3 figures, to appear in ApJ
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