Singularity-free decaying-vacuum cosmologies

Journal Article · Fri May 15 00:00:00 EDT 1992 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.45.3497· OSTI ID:7235731

Abdel-Rahman, A M ^[1]

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1. Department of Physics, Faculty of Science, University of Khartoum, P.O. Box 321, Khartoum (Sudan)

Decaying-vacuum singularity-free cosmological models based on the Chen-Wu ansatz of a cosmological term varying as {ital R}{sup {minus}2} where {ital R} is the scale factor of the Universe are introduced. They describe a closed ever-expanding universe of density parameter {Omega}{ge}1 and with no entropy, horizon, or monopole problems. They include and extend the critical density cosmology of Oezer and Taha. The Oezer-Taha period of phase transition during part of which the pressure is negative occurs in these models. In its wake and throughout the radiation-dominated era the Universe is Einstein--de Sitter--like with {Omega} then and subsequently near unity. Nucleosynthesis proceeds as in the standard model. Consistency with the observed helium abundance and baryon asymmetry allows a maximum vacuum energy close to the radiation energy today. The presence of this vacuum energy could be detrimental to certain theories of galaxy formation. A specific model with initial conditions approaching the hot big bang is studied in detail, particularly as regards the entropy and flatness of the very early Universe.

• OSTI ID: 7235731
• Journal Information: Physical Review, D (Particles Fields); (United States), Vol. 45:10; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMOLOGICAL CONSTANT
TIME DEPENDENCE
COSMOLOGY
VACUUM STATES
EINSTEIN FIELD EQUATIONS
ENTROPY
PHASE TRANSFORMATIONS
QUANTUM GRAVITY
SINGULARITY
EQUATIONS
FIELD EQUATIONS
FIELD THEORIES
PHYSICAL PROPERTIES
QUANTUM FIELD THEORY
THERMODYNAMIC PROPERTIES
661310* - Relativity & Gravitation- (1992-)