A Quantum Cosmological Model with Static and Dynamic Wormholes

Quantization is performed for a Friedmann-Robertson-Walker universe filled with a conformally invariant scalar field and a perfect fluid with equation of state p = . A well-known discrete set of static quantum wormholes is shown to exist for radiation ( = 1/3), and a novel continuous set is found for cosmic strings ( = –1/3), the latter states having throat radii of any size. In both cases wave-packet solutions to the Wheeler-DeWitt equation are obtained with all the properties of evolving quantum wormholes. In the case of a radiation fluid, a detailed analysis of the quantum dynamics is made in the context of the Bohm-de Broglie interpretation. It is shown that a repulsive quantum force inversely proportional to the cube of the scale factor prevents singularities in the quantum domain. For the states considered, there are no particle horizons either.     

Letter: Can Geodesics in Extra Dimensions Solve the Cosmic Light Speed Limit?

It is shown that our 3 + 1 Brane Einstein Universe is a trapped shell in a Higher Dimensional spacetime (Bulk). It is also shown that the Israel Condition acts like a pressure to trap matter in Einstein's Universe, and that if we overcome this pressure, we can make a particle leave Einstein's Universe and enter the Bulk. The conditions that allow the entrance to the Bulk permit its use to send signals or particles faster than the speed of the light, when seen from the Brane due to Brane Lensing. However, in the Bulk the particles remain subluminal. Our model differs from all the standard Braneworlds models, because all matter is trapped in this 3 + 1 Einstein Shell, independently of what the Standard Model might impose. What we propose is a new Braneworld Model using some of the features of the Chung-Freese Model, plus a way to overcome the pressure from the Israel Condition. Our model will remotely resemble the Davoudias Hewett, Rizzo modifications made to Randall-Sundrum Model that allow fermions (not only gravitons) to enter the Bulk, although we must outline that we are proposing a different idea.     

Higher-dimensional string theory in Lyra geometry

In this paper, a study on string theory has been done in five-dimensional space-time based on Lyra geometry. Also a polynomial relation between the two scale factors is assumed. The equations of state for strings have been used for different solutions     

Bianchi-IX string cosmological model in Lyra geometry

A class of cosmological solutions of massive strings for the Bianchi-IX space-time are obtained within the framework of Lyra geometry. Various physical and kinematical properties of the models are discussed     

Eddington and Uncertainty

Arthur Stanley Eddington (1882-1944) is acknowledged to be one of the greatest astrophysicists of the twentieth century, yet his reputation suffered in the 1930s when he embarked on a quest to develop a unified theory of gravity and quantum mechanics. His attempt ultimately proved to be fruitless and was regarded by many physicists as misguided. I will show, however, that Eddingtons work was not so outlandish. His theory applied quantum-mechanical uncertainty to the reference frames of relativity and actually foreshadowed several later results. His philosophy regarding determinism and uncertainty also was quite orthodox at the time. I first review Eddingtons life and philosophy and then discuss his work within the context of his search for a theory of quantum gravity.     

The Apparent Fractal Conjecture: Scaling Features in Standard Cosmologies

This paper presents an analysis of the smoothness problem in cosmology by focussing on the ambiguities originated in the simplifying hypotheses aimed at observationally verifying if the large-scale distribution of galaxies is homogeneous, and conjecturing that this distribution should follow a fractal pattern, in the sense of having a power-law type average density profile, in perturbed standard cosmologies. This is due to a geometrical effect, appearing when certain types of average densities are calculated along the past light cone. The paper starts by reviewing the argument concerning the possibility that the galaxy distribution follows such a scale invariant pattern, and the premises behind the assumption that the spatial homogeneity of standard cosmology can be observable. Next, it is argued that in order to discuss observable homogeneity one needs to make a clear distinction between local and average relativistic densities, and showing how the different distance definitions strongly affect them, leading the various average densities to display asymptotically opposite behaviours. Then the paper revisits Ribeiro's (1995) results, showing that in a fully relativistic treatment some observational average densities of the flat Friedmann model are not well defined at z 0.1, implying that at this range average densities behave in a fundamentally different manner as compared to the linearity of the Hubble law, well valid for z < 1. This conclusion brings into question the widespread assumption that relativistic corrections can always be neglected at low z. It is also shown how some key features of fractal cosmologies can be found in the Friedmann models. In view of those findings, it is suggested that the so-called contradiction between the cosmological principle, and the galaxy distribution forming an unlimited fractal structure, may not exist.     

Jordan—Brans—Dick—Kaluza—Klein宇宙论的一支严格解

本文得到了带∧_(φ)和V_(φ)的 JBDKK 宇宙论在流形 S_1×M_a×M_D 上的一系列新的严格解,进而讨论了它们的某些进化性质.     

Anomalous brightness of quasars resolved by supersymmetry

This article expands the development of the concept of reciprocal symmetry (Ref. 1) and points out that it is (by definition) the supersymmetry of nature. First we derive the relation between the supersymmetric, reciprocal spacetime coordinate transformations of Ref. 1 and the standard Lorentz transformations of relativity. Then we demonstrate or prove the assertion in Ref. 1 that the Robertson-Walker and the Schwarzschild metrics map (exactly) reciprocally. Finally, we derive the relativistic cosmic redshift as a function of distance of the source from the observer in the implied pseudo-dynamic Machian observable universe model. This uniquely consistent physical cosmological model is then applied to interpret the redshifts from quasars. In so doing, we find that this new interpretation puts the quasars considerably closer than does the interpretation of the big-bang theory [see Eq. (36)] and seems to remove the brightness or magnitude anomaly for these objects. As discussed in the Appendix, it also explains why the big-bang interpretation (including the inflationary universe model, etc.) gives good results.     

Quantum cosmology in Ashtekar variables with non-minimally coupled scalar-tensor theory

Using non-minimally coupled scalar-tensor theory in homogeneous and isotropic cosmological model, quantum cosmology has been developed for Ashtekar variables. The wave function has been evaluated by solving the Wheeler-Dewitt (WD) equation and also using path integral formulation. Semi-classical limit using WKB approximation has also been discussed. Finally, the quantum Bohmian trajectories has been studied in detail.     

On Some Exponential Potentials for a Cosmological Scalar Field as Quintessence

We present general exact solutions for two classes of exponential potentials in a scalar field model for quintessence. The coupling is minimal and we consider only dust and scalar field. To some extent, it is possible to reproduce experimental results from supernovae.