Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session X11: Cosmology I |
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Sponsoring Units: DAP Chair: Ram Cowsik, Washington University Room: Hyatt Regency Jacksonville Riverfront City Terrace 7 |
Tuesday, April 17, 2007 10:45AM - 10:57AM |
X11.00001: Dark energy is the cosmological quantum vacuum energy of light particles. The axion and the lightest neutrino. H.J. de Vega We show that the observed dark energy (DE) originates from the cosmological quantum vacuum of light particles which provides a continuous energy distribution able to reproduce the data.Bosons give positive contributions to the DE while fermions yield negative contributions. As usual in field theory, ultraviolet divergences are subtracted from the physical quantities. The subtractions respect the symmetries of the theory and we normalize the physical quantities to zero for the Minkowski vacuum. The resulting finite contributions to the energy density and the pressure from the quantum vacuum grow as $\log a(t)$ where $a(t)$ is the scale factor, while the particle contributions dilute as $1/a^3(t)$. The DE equation of state results $w(z)<-1$.The quantum cosmological vacuum of a scalar particle can produce the observed DE provided:(i)its mass is of the order of $10^{-3}$eV=1 meV, (ii) it is very weakly coupled and (iii) it is stable on the time scale of the age of the universe. The axion appears as a natural candidate. The neutrino vacuum can give negative contributions to the DE. We find that w(z=0) is slightly below - 1 by an amount ranging from $-1.5 10^{-3}$ to $-8 10^{-3}$ while the axion mass results between 4 and 5 meV. DE arises from the quantum vacua of light particles in FRW cosmological space-time in an analogous way to the Casimir effect in Minkowski space-time with non-trivial boundaries. [Preview Abstract] |
Tuesday, April 17, 2007 10:57AM - 11:09AM |
X11.00002: Systematic Corrections to the Deceleration Parameter due to Local Cosmological Inhomogeneity Ali Vanderveld, Ira Wasserman, Eanna Flanagan We will discuss some of the ways that local cosmological inhomogeneity has been found to affect our interpretation of the measurements of the redshifts and luminosity distances of Type Ia supernovae. This discussion will focus on the systematic corrections that one would find even for very large sample sizes as a result of the ``fitting problem,'' wherein the fitting of data to what we would see in a homogeneous universe introduces errors due to the nonlinearity of general relativity. We will then address the recent claim that this effect could be large enough to explain the seemingly anomalous supernova data without the need to introduce dark energy or modified gravity. [Preview Abstract] |
Tuesday, April 17, 2007 11:09AM - 11:21AM |
X11.00003: Locally inhomogeneous cosmology as a possible explanation of dark energy Xinghai Zhao, Grant Mathews, In-Saeng Suh, James Wilson One possible explanation for the origin of the dark energy which contributes the apparent cosmic acceleration involves general relativistic corrections to the Friedmann expansion for a locally inhomogeneous cosmology. The general solution of this scenario has not been established except for cases with special symmetry like the Lemaitre-Tolman-Bondi model. In this talk, I will discuss a numerical simulation approach in which we have derived a scheme to include general relativistic corrections for general 3D inhomogeneities to the Newtonian large scale structure code GADGET-2. In particular, the supernovae magnitude-redshift relation will be examined with this approach as a way to account for the apparent cosmic acceleration. Future improvements of the code and proposed observation tests of this hypothesis will also be discussed. [Preview Abstract] |
Tuesday, April 17, 2007 11:21AM - 11:33AM |
X11.00004: Structure Formation Limits on f(R) Gravity David Bernat, Rachel Bean, Levon Pegosian, Alessandra Silvestri, Mark Trodden Modifications to gravity may explain cosmic acceleration without envoking Dark Energy. Two features emerge in the power spectrum of structure formation in modified gravities that are not seen in standard GR: One, a strong suppression of power manifests at a potentially observable length scale. And two, the growth factor is scale dependent. Both these features make modified gravities difficult to reconscile with LSST observations and limit strongly the allowable types of f(R) modifications. [Preview Abstract] |
Tuesday, April 17, 2007 11:33AM - 11:45AM |
X11.00005: Some exact solutions exhibiting inflation and dark energy Chris Vuille Einstein's equations are solved for the case of a plane-symmetric massless scalar field and cosmological constant. Among the resulting solutions are those that exhibit both rapid inflation at the beginning of the universe and protracted exponential expansion at all times thereafter. This suggests the possibility of a single physical mechanism responsible for both rapid inflation in the early universe and the accelerated expansion thereafter due to dark energy. [Preview Abstract] |
Tuesday, April 17, 2007 11:45AM - 11:57AM |
X11.00006: Primordial Black Hole Minimum Mass James Chisholm In this talk I revisit thermodynamic constraints on primordial black hole (PBH) formation in the early universe. Under the assumption that PBH mass is equal to the cosmological horizon mass, one can use the 2nd Law of Black Hole Thermodynamics to put a lower limit on the PBH mass. In models of PBH formation, however, PBHs are created at some fraction of the horizon mass. I show that this thermodynamic constraint still holds for subhorizon PBH formation. [Preview Abstract] |
Tuesday, April 17, 2007 11:57AM - 12:09PM |
X11.00007: Nucleosynthesis in plasma-redshift cosmology Ari Brynjolfsson We have previously shown that plasma-redshift cosmology explains well the cosmological redshifts, the redshift-distance relation for supernovae Ia (SNe Ia), the cosmic microwave background (CMB), the cosmic X-ray background, and the surface brightness of galaxies. There is no need for dark energy, dark matter, or black holes. We will show that plasma-redshift cosmology, which follows from conventional laws of physics without any new assumptions, leads to quark-gluon plasma conditions that are similar to those surmised ad hoc in the initial phases of the big-bang. These initial conditions exist in objects that are considered black hole candidates (BHCs). This primordial like quark-gluon and photon plasma can escape from the centers of BHCs and renew or recreate protons and neutrons and the light elements previously assumed only to be created in the big-bang. Plasma-redshift cosmology explains therefore the primordial like nucleosynthesis. This also leads to explanation of the gamma-ray bursts. We have failed to find any need or reasonable support for the big-bang explanation. We find that the observed nucleosynthesis and the many other phenomena are consistent with the plasma-redshift cosmology. [Preview Abstract] |
Tuesday, April 17, 2007 12:09PM - 12:21PM |
X11.00008: How can Brane World physics influence Axion temperature dependence, initial vacuum states, and permissible solutions to the Wheeler-De Witt equation? Andrew Beckwith We are investigating if the Jeans instability criteria mandating a low entropy, low temperature initial pre inflation state configuration can be reconciled with thermal conditions of temperatures at or above ten to the 12 Kelvin, or higher, when cosmic inflation physics takes over. We justify this by pointing to the Ashtekar, Pawlowski, and Singh (2006) article about a prior universe being modeled via their quantum bounce hypothesis which states that this prior universe geometrically can be modeled via a discretized Wheeler -- De Witt equation The prior universe would provide thermal excitation into the Jeans instability mandated cooled down initial state, with low entropy, leading to extreme graviton production occurs before the Bogomolnyi inequality compliments the assumption of axion wall mass disappearing due to high temperatures as a way to embed a quadratic chaotic inflationary scalar potential. Our argument pre supposes that the low entropy conditions due to Jeans instability can be successfully reconciled to a requirement later on that axion mass disappears with induced thermal excitation from inputs from the quantum bounce point from a prior universe. This would provide a convenient template for analyzing relic graviton production. [Preview Abstract] |
Tuesday, April 17, 2007 12:21PM - 12:33PM |
X11.00009: What is Fine-Structure Constant? Shantilal Goradia If each Planck time represents OPEN or CLOSE state of the mouth of the quantum wormholes per my proposal in APS MARO7 or physics/0210040 or [1], the total number of microstates in the Hubble time of the universe would be 10$^{60}$. Its substitution for W in entropy equation \textit{S = k Log}$_{e }W$, while dropping the Boltzmann constant of proportionality $k$, one in natural units, would make the increasing disorder rate proportional to \textit{Log}$_{e}$ 10$^{60}$ or 138. This disorder rate is close to the reciprocal of fine-structure coupling constant \textit{$\alpha $} (1/137), confirming my concept that the rate of increase of disorder in the universe at large is reciprocal of microscopic rate of decrease of disorder resulting from the ever increasing shrinkage of Planck length, discussed in DNP06, to make up for the increasing number of Planck lengths in the observable inflation. This would be consistent with the second law of thermodynamics that says that the entropy of an ``isolated'' system does not decrease. Therefore I am documenting my proposal: \textit{$\alpha $ = 1/Log}$_{e} W$, alternatively: $S$ x \textit{$\alpha $} = $k$. [1] Goradia S. G., ``\textit{Why is Gravity so Weak}?'' Journal of Nuclear Radiations and Physics, Volume 1, No 2 107-117 (2006). [Preview Abstract] |
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