Behavior of Friedmann-Robertson-Walker cosmological models in scalar - tensor gravity
May, 199424 pages
Published in:
- Annals Phys. 241 (1995) 128-151
e-Print:
- gr-qc/9405016 [gr-qc]
Report number:
- NSF-ITP-94-45
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Abstract: (arXiv)
We analyze solutions to Friedmann-Robertson-Walker cosmologies in Brans-Dicke theory, where a scalar field is coupled to gravity. Matter is modelled by a -law perfect fluid, including false-vacuum energy as a special case. Through a change of variables, we reduce the field equations from fourth order to second order, and they become equivalent to a two-dimensional dynamical system. We then analyze the entire solution space of this dynamical system, and find that many qualitative features of these cosmologies can be gleaned, including standard non-inflationary or extended inflationary expansion, but also including bifurcations of stable or unstable expansion or contraction, noninflationary vacuum-energy dominated models, and several varieties of ``coasting," ``bouncing," ``hesitating," and ``vacillating" universes. It is shown that inflationary dogma, which states that a universe with curvature and dominated by inflationary matter will always approach a corresponding flat-space solution at late times, does not hold in general for the scalar-tensor theory, but rather that the occurence of inflation depends upon the initial energy of the scalar field relative to the expansion rate. In the case of flat space (), the dynamical system formalism generates some previously known exact power-law solutions.- Friedman model
- space-time: Robertson-Walker
- Brans-Dicke model
- field theory: scalar
- field theory: tensor
- gravitation
- inflation
- field equations
- numerical calculations
References(23)
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