Bulletin of the American Physical Society
2006 Ohio Section of the APS Spring Meeting
Friday–Saturday, March 31–April 1 2006; Detroit, Michigan
Session S1: Astronomy |
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Chair: Rene Bellwied Room: McGregor Center BC |
Friday, March 31, 2006 4:30PM - 4:42PM |
S1.00001: Long Term Variations in the Obliquity of the Earth Gregory Newstadt, Amy Girkin, S.G. Alexander A Hermite integrator with individual time steps (HITS) was used to simulate the orbital and rotational dynamics of the Earth. The Earth's obliquity was calculated including and not including the effects of the other planets and the Moon. Without the Moon, the Earth's obliquity was found to vary between 8.7$^{\circ}$ and 35.3$^{\circ}$ with a general period of about 500 kyr. With the Moon though, the Earth's obliquity was found to be much more stable with variations of only $\pm $ 0.5$^{\circ}$ and a period near 36 kyr. Thus, the Moon can be thought of as a climate regulator as suggested by Laskar (1993). Further study is planned to study the effect of the Earth's oblateness on its obliquity, as well as the effect of each individual planet on Earth's obliquity. [Preview Abstract] |
Friday, March 31, 2006 4:42PM - 4:54PM |
S1.00002: Numerical simulations of gravitational singularities David Garfinkle Numerical simulations are performed of the formation of singularities in gravitational collapse. The spacetimes have no symmetry and are therefore likely to reflect the general behavior of systems under gravitatonal collapse. As the singularity is approached, spatial derivatives in the Einstein field equations become negligible compared to time derivatives. The dynamics at each spatial point thus reduces to the dynamics of a homogeneous spacetime, though a different one for each spatial point. This dynamics can be described using three scale factors, one for each direction in space. For vacuum spacetimes the behavior of these scale factors is oscillatory and chaotic, while for matter with a stiff equation of state, there is a power law behavior of the scale factors as the singularity is approached. [Preview Abstract] |
Friday, March 31, 2006 4:54PM - 5:06PM |
S1.00003: WMAP: A Radiological Analysis Pierre-Marie Robitaille WMAP has been hailed as probing the signature of the early universe yielding precise cosmological findings. In this talk, radiological analysis is applied to these results. WMAP images have an exceedingly low signal:noise on the order of 1.5:1 to 2.5:1. However, prior to obtaining these maps, the stronger galactic signal must be removed. Unlike water suppression in NMR, this is accomplished without a priori knowledge or ability to affect the signal at the source. Galactic signal removal is thus impossible. Attempts to nonetheless remove this signal invariably generates unwanted features in the maps, indistinguishable from real findings, if any. Indeed, the galactic problem alone is sufficient to dismiss any conclusion from WMAP. By using COBE data, it can been seen that these maps contain data processing problems which exceed in strength the analyzed features. The WMAP results are very likely to contain significant random noise fluctuations. NASA should provide each of the 4 yearly maps acquired to date. Comparative analysis should reveal that the WMAP images lack reproducibility - a requirement for credibility in any low signal to noise study. [Preview Abstract] |
Friday, March 31, 2006 5:06PM - 5:18PM |
S1.00004: Collective Motion in Nuclear Collisions and Supernova Explosions T. Strother |
Friday, March 31, 2006 5:18PM - 5:30PM |
S1.00005: A New Model Predicts Supernova Ia without Dark Energy Charles B. Leffert A new model of cosmology with four spatial dimensions will be described. The predicted values of the present cosmological parameters are in agreement with WMAP measurements except for the present value of the deceleration parameter. That present value, predicted to be near zero, also predicts the expansion rate of our universe is not accelerating. The present unknown mass called dark matter is replaced by a different 4-D substance, for which the new model predicts about the same mass. This new 4-D x-stuff scales with the expansion different than matter, but it and a new space-time dynamic, called spatial condensation, drives the expansion rate towards a constant value. The entire model and all of its predictions flow from a new dimensionless universal constant, $\kappa $ = G$\rho $t$^{2}$. Neither the cosmological constant nor dark energy is needed to predict good agreement with supernova measurements, but a new procedure of analyzing the data shows much larger inherent scatter, for which the new model also explains. [Preview Abstract] |
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