* Astronomy

Title: The Spatially Closed Universe
Authors: Chan-Gyung Park
(Version v2)

The general world model for homogeneous and isotropic universe has been proposed. For this purpose, we introduce a global and fiducial system of reference (world reference frame) constructed on a 4+1 Minkowski space-time that is embedding the universe, and define the line element as the separation between two neighbouring events that are distinct in space and time, as viewed in the world reference frame. The effect of cosmic expansion on the measurement of physical distance has been included in the new metric, which differs from the Friedmann-Robertson-Walker metric where the spatial separation is measured on the hypersurface at a constant time, regardless of the dynamical state of space. The Einstein's field equations with the new metric imply that closed, flat, and open universes are filled with positive, zero, and negative energy, respectively. We have demonstrated that the flat universe is empty and stationary, equivalent to the Minkowski space-time, and that the universe with positive energy density is always spatially closed and finite. In the closed universe, the proper time of a comoving observer does not elapse uniformly as judged in the world reference frame, in which both cosmic expansion and time-varying light speeds cannot exceed the limiting speed of the special relativity. We have also reconstructed cosmic evolution histories of the closed world models that are consistent with recent astronomical observations, and derived useful formulas such as energy-momentum relation of particles, redshift, total energy in the universe, cosmic distance and time scales, and so forth. It has been also shown that the inflation with positive acceleration at the earliest epoch is improbable.

Read more (146kb, PDF)

A cosmologist has created a mathematical model that he says shows space-time, contrary to common wisdom, did not begin with the Big Bang. Instead, the model suggests a universe pretty much like the one we live in today existed before the event, except it was contracting instead of expanding. If ever proven, the idea could force a complete rethinking of the origins of the cosmos and perhaps even open a doorway to an endless future.

Read more

Details of what the universe was like before the big bang may be forever lost to us, according to a new analysis. Einstein's theory of gravity, general relativity, describes the evolution of the cosmos but breaks down at the moment of the big bang, preventing researchers from understanding its origins. To glimpse behind the veil, a researcher has applied a speculative theory that treats the universe as pixellated into tiny atom-like units of space and time. His findings suggest that experiments would never be sensitive enough to fully reconstruct the state of the universe before the bang.

"If that is the case, then we're not able to determine the precise origin of the universe.  It would always remain a philosophical scenario" - Martin Bojowald, theoretical physicist of Pennsylvania State University in University Park.

Read more

Title: The return of a static universe and the end of cosmology
Authors; Lawrence M. Krauss, Robert J. Scherrer
(Version v3)

We demonstrate that as we extrapolate the current CDM universe forward in time, all evidence of the Hubble expansion will disappear, so that observers in our island universe will be fundamentally incapable of determining the true nature of the universe, including the existence of the highly dominant vacuum energy, the existence of the CMB, and the primordial origin of light elements. With these pillars of the modern Big Bang gone, this epoch will mark the end of cosmology and the return of a static universe. In this sense, the coordinate system appropriate for future observers will perhaps fittingly resemble the static coordinate system in which the de Sitter universe was first presented.

Read more  

Read more  (7kb, PDF)

Ed ~ See the Weyl curvature hypothesis by mathematical physicist Roger Penrose and the `resetting` of Spacetme.