Mathematics – Logic
Scientific paper
Apr 1998
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998aps..apr..i709a&link_type=abstract
American Physical Society, APS/AAPT Joint April Meeting, April 18-21, 1998 Columbus, Ohio, abstract #I7.09
Mathematics
Logic
Scientific paper
Inflationary scenarios solve the flatness, horizon, and monopole problems, but raise new difficulties: the required parameters are typically contrived and unnaturally small, the postulated scalar field is not integrated with standard physics, a ``graceful exit'' has proved elusive, and the prediction Ω _0=1 may be in conflict with observation. In addition, the cosmological constant and classical singularity problems are left unresolved. We discuss a new cosmological model which was briefly outlined in a previous publication.(R.E. Allen, Int. J. Mod. Phys. A 12, 2385 (1997) and hep-th/9612041) In this model, local gravity is described as usual by the Einstein field equations, but the global metric of the universe is determined by a cosmological instanton. This description immediately yields a metric in which the global curvature of spacetime approaches zero as tarrow ∞, and in which the scale factor R(t) is proportional to t at all times, rather than t^1/2 (in a radiation-dominated universe) or t^2/3 (in a matter-dominated universe). As a result, the horizon retreats to infinity, so that the observable universe was always causally connected. The nearly scale-invariant power spectrum for the current distribution of matter is still attributed to primordial fluctuations. Since R(t) is much larger than in standard Friedmann models, primordial relics like monopoles have a very low density. In addition, spacetime is required to be asymptotically flat (by topology) even if Ω _0neq 1. The cosmological constant is identically zero, ^1 and the classical singularity at t=0 is physically acceptable, because it is analogous to the singularity at the center of a superfluid vortex. The fact that R(t) is proportional to t also implies a larger age for the universe. For example, if h=0.67, standard cosmology implies that t_0≈ 10 Gyr, whereas the present model yields t_0≈ 15 Gyr.
Allen Roland
Mondragon Antonio
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